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Sample records for foxo3 tumor suppressor

  1. PLK1 is a binding partner and a negative regulator of FOXO3 tumor suppressor.

    Science.gov (United States)

    Bucur, Octavian; Stancu, Andreea Lucia; Muraru, Maria Sinziana; Melet, Armelle; Petrescu, Stefana Maria; Khosravi-Far, Roya

    2014-01-01

    FOXO family members (FOXOs: FOXO1, FOXO3, FOXO4 and FOXO6) are important transcription factors and tumor suppressors controlling cell homeostasis and cell fate. They are characterized by an extraordinary functional diversity, being involved in regulation of cell cycle, proliferation, apoptosis, DNA damage response, oxidative detoxification, cell differentiation and stem cell maintenance, cell metabolism, angiogenesis, cardiac and other organ's development, aging, and other critical cellular processes. FOXOs are tightly regulated by reversible phosphorylation, ubiquitination, acetylation and methylation. Interestingly, the known kinases phosphorylate only a small percentage of the known or predicted FOXOs phosphorylation sites, suggesting that additional kinases that phosphorylate and control FOXOs activity exist. In order to identify novel regulators of FOXO3, we have employed a proteomics screening strategy. Using HeLa cancer cell line and a Tandem Affinity Purification followed by Mass Spectrometry analysis, we identified several proteins as binding partners of FOXO3. Noteworthy, Polo Like Kinase 1 (PLK1) proto-oncogene was one of the identified FOXO3 binding partners. PLK1 plays a critical role during cell cycle (G2-M transition and all phases of mitosis) and in maintenance of genomic stability. Our experimental results presented in this manuscript demonstrate that FOXO3 and PLK1 exist in a molecular complex through most of the phases of the cell cycle, with a higher occurrence in the G2-M cell cycle phases. PLK1 induces translocation of FOXO3 from the nucleus to the cytoplasm and suppresses FOXO3 activity, measured by the decrease in the pro-apoptotic Bim protein levels and in the cell cycle inhibitor protein p27. Furthermore, PLK1 can directly phosphorylate FOXO3 in an in vitro kinase assay. These results present the discovery of PLK1 proto-oncogene as a binding partner and a negative regulator of FOXO3 tumor suppressor.

  2. FoxO3a与肿瘤的发生和发展%Role of FoxO3a in the occurrence and development of tumors

    Institute of Scientific and Technical Information of China (English)

    何时

    2012-01-01

    Forkhead box O (FoxO) 3a is one of the FoxO family members. With the role of tumor suppressor genes, it can regulate the development of a variety of tumors, including breast cancer, prostate cancer, leukemia, glioblastoma, and so oa FoxO3a is regulated by many lands of signaling pathways, particularly the phosphatidylinositol 3-kinase/protein kinase B (PDK/ Akt) signaling pathway. As the target molecule of PI3K/AKT signal pathway, the activity of FoxO3a is regulated by AKT phosphorylation and dephosphorylation. FoxO3a plays an important role in regulation of downstream signaling molecules, such as Bim, FasL, p27kipl transcription, to induce apoptosis of tumor cells. The activity and distribution of FoxO3a can be modulated by drugs. Therefore, FoxO3a is expected to become the new idea of cancer treatment%叉头转录因子O亚型(forkhead box O,FoxO) 3a是FoxO家族一员,具有抑癌基因的作用,调控多种肿瘤的发生发展,包括乳腺癌、前列腺癌、白血病、胶质母细胞瘤等.FoxO3a作为磷脂酰肌醇3-激酶/蛋白激酶B (phosphatidylinositol 3-kinase/protein kinase B,PI3K/Akt)信号通路的重要靶分子,主要通过AKT磷酸化与去磷酸化起作用,调节其活性以及下游信号分子如细胞死亡调解因子、Fas配体和细胞周期蛋白依赖性激酶等转录作用,诱导肿瘤细胞凋亡.药物调控FoxO3a的活性和分布有望成为癌症治疗的新思路.

  3. Tumor suppressor and hepatocellular carcinoma

    Institute of Scientific and Technical Information of China (English)

    Juliette Martin; Jean-Frangois Dufour

    2008-01-01

    A few signaling pathways are driving the growth of hepatocellular carcinoma. Each of these pathways possesses negative regulators. These enzymes, which normally suppress unchecked cell proliferation, are circumvented in the oncogenic process, either the over-activity of oncogenes is sufficient to annihilate the activity of tumor suppressors or tumor suppressors have been rendered ineffective. The loss of several key tumor suppressors has been described in hepatocellular carcinoma. Here, we systematically review the evidence implicating tumor suppressors in the development of hepatocellular carcinoma.

  4. Neurons and tumor suppressors.

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    Zochodne, Douglas W

    2014-08-20

    Neurons choose growth pathways with half hearted reluctance, behavior that may be appropriate to maintain fixed long lasting connections but not to regenerate them. We now recognize that intrinsic brakes on regrowth are widely expressed in these hesitant neurons and include classical tumor suppressor molecules. Here, we review how two brakes, PTEN (phosphatase and tensin homolog deleted on chromosome 10) and retinoblastoma emerge as new and exciting knockdown targets to enhance neuron plasticity and improve outcome from damage or disease.

  5. Neurons and Tumor Suppressors

    OpenAIRE

    Douglas W Zochodne

    2014-01-01

    Neurons choose growth pathways with half hearted reluctance, behavior that may be appropriate to maintain fixed long lasting connections but not to regenerate them. We now recognize that intrinsic brakes on regrowth are widely expressed in these hesitant neurons and include classical tumor suppressor molecules. Here, we review how two brakes, PTEN (phosphatase and tensin homolog deleted on chromosome 10) and retinoblastoma emerge as new and exciting knockdown targets to e...

  6. Spontaneous presence of FOXO3-specific T cells in cancer patients

    DEFF Research Database (Denmark)

    Larsen, Stine Kiaer; Ahmad, Shamaila Munir; Idorn, Manja

    2014-01-01

    In the present study, we describe forkhead box O3 (FOXO3)-specific, cytotoxic CD8(+) T cells existent among peripheral-blood mononuclear cells (PBMCs) of cancer patients. FOXO3 immunogenicity appears specific, as we did not detect reactivity toward FOXO3 among T cells in healthy individuals. FOXO3...... may naturally serve as a target antigen for tumor-reactive T cells as it is frequently over-expressed in cancer cells. In addition, expression of FOXO3 plays a critical role in immunosuppression mediated by tumor-associated dendritic cells (TADCs). Indeed, FOXO3-specific cytotoxic T lymphocytes (CTLs......) were able to specifically recognize and kill both FOXO3-expressing cancer cells as well as dendritic cells. Thus, FOXO3 was processed and presented by HLA-A2 on the cell surface of both immune cells and cancer cells. As FOXO3 programs TADCs to become tolerogenic, FOXO3 signaling thereby comprises...

  7. EGCG inhibits growth of human pancreatic tumors orthotopically implanted in Balb C nude mice through modulation of FKHRL1/FOXO3a and neuropilin.

    Science.gov (United States)

    Shankar, Sharmila; Marsh, Luke; Srivastava, Rakesh K

    2013-01-01

    Human pancreatic cancer is currently one of the fourth leading causes of cancer-related mortality with a 5-year survival rate of less than 5 %. Since pancreatic carcinoma is largely refractory to conventional therapies, there is a strong medical need for the development of novel and innovative cancer preventive strategies. The forkhead transcription factors of the O class (FOXO) play a major role in cell proliferation, angiogenesis, metastasis, and tumorigenesis. The objectives of this study were to examine whether FKHRL1/FOXO3a modulates antitumor activity of (-)-epigallocatechin-3-gallate (EGCG), an active ingredient in green tea, in pancreatic cancer model in vivo. PANC-1 cells were orthotopically implanted into Balb c nude mice and gavaged with EGCG after tumor formation. Cell proliferation and apoptosis were measured by Ki67 and TUNEL staining, respectively. The expression of PI3K, AKT, ERK, and FOXO3a/FKHRL1 and its target genes were measured by the western blot analysis and/or q-RT-PCR. FOXO-DNA binding was measured by gel shift assay. EGCG-treated mice showed significant inhibition in tumor growth which was associated with reduced phosphorylation of ERK, PI3K, AKT, and FKHRL1/FOXO3a, and modulation of FOXO target genes. EGCG induced apoptosis by upregulating Bim and activating caspase-3. EGCG modulated markers of cell cycle (p27/KIP1), angiogenesis (CD31, VEGF, IL-6, IL-8, SEMA3F, and HIF1α), and metastasis (MMP2 and MMP7). The inhibition of VEGF by EGCG was associated with suppression of neuropilin. EGCG inhibited epithelial-mesenchymal transition by upregulating the expression of E-cadherin and inhibiting the expression of N-cadherin and Zeb1. These data suggest that EGCG inhibits pancreatic cancer orthotopic tumor growth, angiogenesis, and metastasis which are associated with inhibition of PI3K/AKT and ERK pathways and activation of FKHRL1/FOXO3a. As a conclusion, EGCG can be used for the prevention and/or treatment of pancreatic cancer.

  8. Tumor suppressor molecules and methods of use

    Science.gov (United States)

    Welch, Peter J.; Barber, Jack R.

    2004-09-07

    The invention provides substantially pure tumor suppressor nucleic acid molecules and tumor suppressor polypeptides. The invention also provides hairpin ribozymes and antibodies selective for these tumor suppressor molecules. Also provided are methods of detecting a neoplastic cell in a sample using detectable agents specific for the tumor suppressor nucleic acids and polypeptides.

  9. Tumor suppressor ARF

    Science.gov (United States)

    Través, Paqui G.; Luque, Alfonso; Hortelano, Sonsoles

    2012-01-01

    ARF (alternative reading frame) is one of the most important tumor regulator playing critical roles in controlling tumor initiation and progression. Recently, we have demonstrated a novel and unexpected role for ARF as modulator of inflammatory responses. PMID:23162766

  10. Tolerogenic pDCs: spotlight on Foxo3.

    Science.gov (United States)

    Bronte, Vincenzo

    2011-04-01

    Cancer creates a peculiar inflammatory environment enriched for transcription factors with a negative influence on adaptive immunity. In this issue of the JCI, Watkins and colleagues identify Foxo3 as a master regulator of the tolerogenic program in tumor-associated, plasmacytoid DCs (pDCs). Foxo3 enables pDCs to induce tolerance in tumor antigen-specific CD8+ T cells, turning them into regulatory lymphocytes capable of inhibiting nearby CD8+ T lymphocytes. Provision of tumor-specific CD4+ T helper cells interrupts this circuit by inhibiting Foxo3 expression and fully licensing the antigen-presenting ability of pDCs. These data identify a new target for therapeutic intervention and provide insight into the transcription factor interplay in myeloid cells recruited to the cancer microenvironment.

  11. MicroRNA-96 promotes the proliferation of colorectal cancer cells and targets tumor protein p53 inducible nuclear protein 1, forkhead box protein O1 (FOXO1) and FOXO3a.

    Science.gov (United States)

    Gao, Feng; Wang, Wenhui

    2015-02-01

    MicroRNAs (miRNAs) are a conserved class of small, endogenous, non protein-coding RNA molecules that are capable of regulating gene expression at post-transcriptional levels and are involved in diverse cellular processes, including cancer pathogenesis. It has previously been reported that miRNA-96 (miR-96) is overexpressed in human colorectal cancer (CRC). However, the underlying mechanism of miR-96 regulation in CRC remains to be elucidated. In the present study, miR-96 was confirmed to be upregulated in CRC tissues by reverse transcription quantitative polymerase chain reaction. MTT assay, colony formation assay and cell cycle analysis revealed that miR-96 overexpression led to increased tumor cell viability, colony formation ability and cell cycle progression. By contrast, inhibition of miR-96 resulted in the suppression of cell proliferation. It was also demonstrated that miR-96 reduced the messenger RNA and protein expression levels of tumor protein p53 inducible nuclear protein 1 (TP53INP1), forkhead box protein O1 (FOXO1) and FOXO3a, which are closely associated with cell proliferation. A luciferase reporter assay indicated that miR-96 inhibited luciferase intensity controlled by the 3'UTRs of TP53INP1, FOXO1 and FOXO3a. In conclusion, the results of the present study demonstrated that miR-96 contributed to CRC cell growth and that TP53INP1, FOXO1 and FOXO3a were direct targets of miR-96, suggesting that miR-96 may have the potential to be used in the development of miRNA‑based therapies for CRC patients.

  12. Tumor suppressor identified as inhibitor of inflammation

    Science.gov (United States)

    Scientists at NCI have found that a protein, FBXW7, which acts as a tumor suppressor, is also important for the reduction in strength of inflammatory pathways. It has long been recognized that a complex interaction exists between cancer causing mechanisms

  13. FOXO3a promotes gastric cancer cell migration and invasion through the induction of cathepsin L

    Science.gov (United States)

    Zhang, Wen; Yuan, Wei; Zhao, Naiqing; Li, Qian; Cui, Yuehong; Wang, Yan; Li, Wei; Sun, Yihong; Liu, Tianshu

    2016-01-01

    Forkhead box O3A (FOXO3a) is an important transcription factor involved in various human cancers. However, the role of FOXO3a in regulating the invasion and metastasis of gastric cancer cells has not been clarified. Here, we report that FOXO3a overexpression promoted migration and invasion of gastric cancer cells by upregulating cathepsin L. FOXO3a knockdown suppressed migration and invasion and also downregulated cathepsin L expression in gastric cancer cells. Silencing cathepsin L in these cells suppressed FOXO3a overexpression-induced cell migration and invasion. Mechanistic studies revealed that FOXO3a increased cathepsin L promoter activation, and cathepsin L overexpression repressed E-cadherin expression, causing gastric cancer cells to undergo epithelial-mesenchymal transition (EMT). Our data reveal a previously unexplored function of FOXO3a in gastric cancer invasion by regulating proteins involved in extracellular matrix (ECM) degradation and EMT. We suggest that FOXO3a may be of prognostic value and a potential therapeutic target in blocking tumor metastasis. PMID:27127880

  14. Targeting tumor suppressor genes for cancer therapy.

    Science.gov (United States)

    Liu, Yunhua; Hu, Xiaoxiao; Han, Cecil; Wang, Liana; Zhang, Xinna; He, Xiaoming; Lu, Xiongbin

    2015-12-01

    Cancer drugs are broadly classified into two categories: cytotoxic chemotherapies and targeted therapies that specifically modulate the activity of one or more proteins involved in cancer. Major advances have been achieved in targeted cancer therapies in the past few decades, which is ascribed to the increasing understanding of molecular mechanisms for cancer initiation and progression. Consequently, monoclonal antibodies and small molecules have been developed to interfere with a specific molecular oncogenic target. Targeting gain-of-function mutations, in general, has been productive. However, it has been a major challenge to use standard pharmacologic approaches to target loss-of-function mutations of tumor suppressor genes. Novel approaches, including synthetic lethality and collateral vulnerability screens, are now being developed to target gene defects in p53, PTEN, and BRCA1/2. Here, we review and summarize the recent findings in cancer genomics, drug development, and molecular cancer biology, which show promise in targeting tumor suppressors in cancer therapeutics.

  15. Microbial Regulation of p53 Tumor Suppressor.

    Directory of Open Access Journals (Sweden)

    Alexander I Zaika

    2015-09-01

    Full Text Available p53 tumor suppressor has been identified as a protein interacting with the large T antigen produced by simian vacuolating virus 40 (SV40. Subsequent research on p53 inhibition by SV40 and other tumor viruses has not only helped to gain a better understanding of viral biology, but also shaped our knowledge of human tumorigenesis. Recent studies have found, however, that inhibition of p53 is not strictly in the realm of viruses. Some bacterial pathogens also actively inhibit p53 protein and induce its degradation, resulting in alteration of cellular stress responses. This phenomenon was initially characterized in gastric epithelial cells infected with Helicobacter pylori, a bacterial pathogen that commonly infects the human stomach and is strongly linked to gastric cancer. Besides H. pylori, a number of other bacterial species were recently discovered to inhibit p53. These findings provide novel insights into host-bacteria interactions and tumorigenesis associated with bacterial infections.

  16. SIRT1, Is It a Tumor Promoter or Tumor Suppressor?

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    Chu-Xia Deng

    2009-01-01

    Full Text Available SIRT1 has been considered as a tumor promoter because of its increased expression in some types of cancers and its role in inactivating proteins that are involved in tumor suppression and DNA damage repair. However, recent studies demonstrated that SIRT1 levels are reduced in some other types of cancers, and that SIRT1 deficiency results in genetic instability and tumorigenesis, while overexpression of SIRT1 attenuates cancer formation in mice heterozygous for tumor suppressor p53 or APC. Here, I review these recent findings and discuss the possibility that activation of SIRT1 both extends lifespan and inhibits cancer formation.

  17. Tumor suppressor genes in familial adenomatous polyposis.

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    Eshghifar, Nahal; Farrokhi, Naser; Naji, Tahereh; Zali, Mohammadreza

    2017-01-01

    Colorectal cancer (CRC) is mostly due to a series of genetic alterations that are being greatly under the influence of the environmental factors. These changes, mutational or epigenetic modifications at transcriptional forefront and/or post-transcriptional effects via miRNAs, include inactivation and the conversion of proto-oncogene to oncogenes, and/or inactivation of tumor suppressor genes (TSG). Here, a thorough review was carried out on the role of TSGs with the focus on the APC as the master regulator, mutated genes and mal-/dysfunctional pathways that lead to one type of hereditary form of the CRC; namely familial adenomatous polyposis (FAP). This review provides a venue towards defining candidate genes that can be used as new PCR-based markers for early diagnosis of FAP. In addition to diagnosis, defining the modes of genetic alterations will open door towards genome editing to either suppress the disease or reduce its progression during the course of action.

  18. The tumor suppressor CDKN3 controls mitosis.

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    Nalepa, Grzegorz; Barnholtz-Sloan, Jill; Enzor, Rikki; Dey, Dilip; He, Ying; Gehlhausen, Jeff R; Lehmann, Amalia S; Park, Su-Jung; Yang, Yanzhu; Yang, Xianlin; Chen, Shi; Guan, Xiaowei; Chen, Yanwen; Renbarger, Jamie; Yang, Feng-Chun; Parada, Luis F; Clapp, Wade

    2013-06-24

    Mitosis is controlled by a network of kinases and phosphatases. We screened a library of small interfering RNAs against a genome-wide set of phosphatases to comprehensively evaluate the role of human phosphatases in mitosis. We found four candidate spindle checkpoint phosphatases, including the tumor suppressor CDKN3. We show that CDKN3 is essential for normal mitosis and G1/S transition. We demonstrate that subcellular localization of CDKN3 changes throughout the cell cycle. We show that CDKN3 dephosphorylates threonine-161 of CDC2 during mitotic exit and we visualize CDC2(pThr-161) at kinetochores and centrosomes in early mitosis. We performed a phosphokinome-wide mass spectrometry screen to find effectors of the CDKN3-CDC2 signaling axis. We found that one of the identified downstream phosphotargets, CKβ phosphorylated at serine 209, localizes to mitotic centrosomes and controls the spindle checkpoint. Finally, we show that CDKN3 protein is down-regulated in brain tumors. Our findings indicate that CDKN3 controls mitosis through the CDC2 signaling axis. These results have implications for targeted anticancer therapeutics.

  19. Studies of Tumor Suppressor Genes via Chromosome Engineering

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    Hiroyuki Kugoh

    2015-12-01

    Full Text Available The development and progression of malignant tumors likely result from consecutive accumulation of genetic alterations, including dysfunctional tumor suppressor genes. However, the signaling mechanisms that underlie the development of tumors have not yet been completely elucidated. Discovery of novel tumor-related genes plays a crucial role in our understanding of the development and progression of malignant tumors. Chromosome engineering technology based on microcell-mediated chromosome transfer (MMCT is an effective approach for identification of tumor suppressor genes. The studies have revealed at least five tumor suppression effects. The discovery of novel tumor suppressor genes provide greater understanding of the complex signaling pathways that underlie the development and progression of malignant tumors. These advances are being exploited to develop targeted drugs and new biological therapies for cancer.

  20. Studies of Tumor Suppressor Genes via Chromosome Engineering.

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    Kugoh, Hiroyuki; Ohira, Takahito; Oshimura, Mitsuo

    2015-12-30

    The development and progression of malignant tumors likely result from consecutive accumulation of genetic alterations, including dysfunctional tumor suppressor genes. However, the signaling mechanisms that underlie the development of tumors have not yet been completely elucidated. Discovery of novel tumor-related genes plays a crucial role in our understanding of the development and progression of malignant tumors. Chromosome engineering technology based on microcell-mediated chromosome transfer (MMCT) is an effective approach for identification of tumor suppressor genes. The studies have revealed at least five tumor suppression effects. The discovery of novel tumor suppressor genes provide greater understanding of the complex signaling pathways that underlie the development and progression of malignant tumors. These advances are being exploited to develop targeted drugs and new biological therapies for cancer.

  1. Cisplatin Induces Overactivation of the Dormant Primordial Follicle through PTEN/AKT/FOXO3a Pathway which Leads to Loss of Ovarian Reserve in Mice

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    Chang, Eun Mi; Lim, Eunjin; Yoon, Sookyoung; Jeong, Kyungah; Bae, Sijeong; Lee, Dong Ryul; Yoon, Tae Ki

    2015-01-01

    Cisplatin is a first-line chemotherapeutic agent for ovarian cancer that acts by promoting DNA cross links and adduct. However drug resistance and considerable side effects including reproductive toxicity remain a significant challenge. PTEN is well known as a tumor suppressor function which plays a fundamental role in the regulation of the cell cycle, apoptosis and development of cancer. At the same time PTEN has been revealed to be critically important for the maintenance of the primordial follicle pool. In this study, we investigated the role of PTEN/Akt/FOXO3 pathway in cisplatin-induced primordial follicle depletion. Cisplatin induced ovarian failure mouse model was used to evaluate how this pathway involves. In vitro maturation was used for oocyte rescue after cisplatin damage. We found that cisplatin treatment decreased PTEN levels, leading to a subsequent increase in the phosphorylation of key molecules in the pathway. The activation of the PTEN/Akt/FOXO3 pathway cascade increased cytoplasmic translocation of FOXO3a in cisplatin-treated follicles, which in turn increased the pool size of growing follicles, and rapidly depleted the number of dormant follicles. Once activated, the follicles were more prone to apoptosis, and their cumulus cells showed a loss of luteinizing hormone (LH) receptor expression, which leads to failure during final maturation and ovulation. In vitro maturation to rescue oocytes in a cisplatin-treated mouse model resulted in successful maturation and fertilization. This study is the first to show the involvement of the PTEN/Akt/FOXO3 pathway in premature ovarian failure after cisplatin treatment and the possibility of rescue through in vitro maturation. PMID:26656301

  2. The ING tumor suppressor genes: status in human tumors.

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    Guérillon, Claire; Bigot, Nicolas; Pedeux, Rémy

    2014-04-01

    ING genes (ING1-5) were identified has tumor suppressor genes. ING proteins are characterized as Type II TSGs since they are involved in the control of cell proliferation, apoptosis and senescence. They may also function as Type I TSGs since they are also involved in DNA replication and repair. Most studies have reported that they are frequently lost in human tumors and epigenetic mechanisms or misregulation of their transcription may be involved. Recently, studies have described that this loss may be caused by microRNA inhibition. Here, we summarize the current knowledge on ING functions, their involvement in tumor suppression and, in order to give a full assessment of the current knowledge, we review all the studies that have examined ING status in human cancers.

  3. Tumor suppressors status in cancer cell line Encyclopedia.

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    Sonkin, Dmitriy; Hassan, Mehedi; Murphy, Denis J; Tatarinova, Tatiana V

    2013-08-01

    Tumor suppressors play a major role in the etiology of human cancer, and typically achieve a tumor-promoting effect upon complete functional inactivation. Bi-allelic inactivation of tumor suppressors may occur through genetic mechanisms (such as loss of function mutation, copy number (CN) loss, or loss of heterozygosity (LOH)), epigenetic mechanisms (such as promoter methylation or histone modification), or a combination of the two. We report systematically derived status of 69 known or putative tumor suppressors, across 799 samples of the Cancer Cell Line Encyclopedia. In order to generate such resource we constructed a novel comprehensive computational framework for the assessment of tumor suppressor functional "status". This approach utilizes several orthogonal genomic data types, including mutation data, copy number, LOH and expression. Through correlation with additional data types (compound sensitivity and gene set activity) we show that this integrative method provides a more accurate assessment of tumor suppressor status than can be inferred by expression, copy number, or mutation alone. This approach has the potential for a more realistic assessment of tumor suppressor genes for both basic and translational oncology research.

  4. Structure of the Wilms Tumor Suppressor

    Energy Technology Data Exchange (ETDEWEB)

    Stoll, R.; Lee, B.M.; Debler, E.W.; Laity, J.H.; Wilson, I.A.; Dyson, H.J.; Wright, P.E.

    2009-06-04

    The zinc finger domain of the Wilms tumor suppressor protein (WT1) contains four canonical Cys{sub 2}His{sub 2} zinc fingers. WT1 binds preferentially to DNA sequences that are closely related to the EGR-1 consensus site. We report the structure determination by both X-ray crystallography and NMR spectroscopy of the WT1 zinc finger domain in complex with DNA. The X-ray structure was determined for the complex with a cognate 14 base-pair oligonucleotide, and composite X-ray/NMR structures were determined for complexes with both the 14 base-pair and an extended 17 base-pair DNA. This combined approach allowed unambiguous determination of the position of the first zinc finger, which is influenced by lattice contacts in the crystal structure. The crystal structure shows the second, third and fourth zinc finger domains inserted deep into the major groove of the DNA where they make base-specific interactions. The DNA duplex is distorted in the vicinity of the first zinc finger, with a cytidine twisted and tilted out of the base stack to pack against finger 1 and the tip of finger 2. By contrast, the composite X-ray/NMR structures show that finger 1 continues to follow the major groove in the solution complexes. However, the orientation of the helix is non-canonical, and the fingertip and the N terminus of the helix project out of the major groove; as a consequence, the zinc finger side-chains that are commonly involved in base recognition make no contact with the DNA. We conclude that finger 1 helps to anchor WT1 to the DNA by amplifying the binding affinity although it does not contribute significantly to binding specificity. The structures provide molecular level insights into the potential consequences of mutations in zinc fingers 2 and 3 that are associated with Denys-Drash syndrome and nephritic syndrome. The mutations are of two types, and either destabilize the zinc finger structure or replace key base contact residues.

  5. The estrogen receptor α is the key regulator of the bifunctional role of FoxO3a transcription factor in breast cancer motility and invasiveness

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    Sisci, Diego; Maris, Pamela; Cesario, Maria Grazia; Anselmo, Wanda; Coroniti, Roberta; Trombino, Giovanna Elvi; Romeo, Francesco; Ferraro, Aurora; Lanzino, Marilena; Aquila, Saveria; Maggiolini, Marcello; Mauro, Loredana; Morelli, Catia; Andò, Sebastiano

    2013-01-01

    The role of the Forkhead box class O (FoxO)3a transcription factor in breast cancer migration and invasion is controversial. Here we show that FoxO3a overexpression decreases motility, invasiveness, and anchorage-independent growth in estrogen receptor α-positive (ERα+) cancer cells while eliciting opposite effects in ERα-silenced cells and in ERα-negative (ERα−) cell lines, demonstrating that the nuclear receptor represents a crucial switch in FoxO3a control of breast cancer cell aggressiveness. In ERα+ cells, FoxO3a-mediated events were paralleled by a significant induction of Caveolin-1 (Cav1), an essential constituent of caveolae negatively associated to tumor invasion and metastasis. Cav1 induction occurs at the transcriptional level through FoxO3a binding to a Forkhead responsive core sequence located at position −305/−299 of the Cav1 promoter. 17β-estradiol (E2) strongly emphasized FoxO3a effects on cell migration and invasion, while ERα and Cav1 silencing were able to reverse them, demonstrating that both proteins are pivotal mediators of these FoxO3a controlled processes. In vivo, an immunohistochemical analysis on tissue sections from patients with ERα+ or ERα− invasive breast cancers or in situ ductal carcinoma showed that nuclear FoxO3a inversely (ERα+) or directly (ERα−) correlated with the invasive phenotype of breast tumors. In conclusion, FoxO3a role in breast cancer motility and invasion depends on ERα status, disclosing a novel aspect of the well-established FoxO3a/ERα interplay. Therefore FoxO3a might become a pursuable target to be suitably exploited in combination therapies either in ERα+ or ERα− breast tumors. PMID:24047697

  6. RET is a potential tumor suppressor gene in colorectal cancer

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    Luo, Yanxin; Tsuchiya, Karen D.; Park, Dong Il; Fausel, Rebecca; Kanngurn, Samornmas; Welcsh, Piri; Dzieciatkowski, Slavomir; Wang, Jianping; Grady, William M.

    2012-01-01

    Cancer arises as the consequence of mutations and epigenetic alterations that activate oncogenes and inactivate tumor suppressor genes. Through a genome-wide screen for methylated genes in colon neoplasms, we identified aberrantly methylated RET in colorectal cancer. RET, a transmembrane receptor tyrosine kinase and a receptor for the GDNF-family ligands, was one of the first oncogenes to be identified and has been shown to be an oncogene in thyroid cancer and pheochromocytoma. However, unexpectedly, we found RET is methylated in 27% of colon adenomas and in 63% of colorectal cancers, and now provide evidence that RET has tumor suppressor activity in colon cancer. The aberrant methylation of RET correlates with decreased RET expression, whereas the restoration of RET in colorectal cancer cell lines results in apoptosis. Furthermore, in support of a tumor suppressor function of RET, mutant RET has also been found in primary colorectal cancer. We now show that these mutations inactivate RET, which is consistent with RET being a tumor suppressor gene in the colon. These findings suggest that the aberrant methylation of RET and the mutational inactivation of RET promote colorectal cancer formation and that RET can serve as a tumor suppressor gene in the colon. Moreover, the increased frequency of methylated RET in colon cancers compared to adenomas suggests RET inactivation is involved in the progression of colon adenomas to cancer. PMID:22751117

  7. Some facts and thoughts: p73 as a tumor suppressor gene in the network of tumor suppressors

    Directory of Open Access Journals (Sweden)

    Boominathan Lakshmanane

    2007-04-01

    Full Text Available Abstract The question of whether p73 is a tumor suppressor gene, is not yet answered with full confidence. The lack of spontaneous tumor formation in p73 null mice and infrequent p73 mutations seen in a variety of cancers analyzed would straightaway negate its role as a primary tumor suppressor gene. However, accumulating evidence suggest that p73 gene and its target genes are hypermethylated in the cancer of lymphoid origin. Here I discuss some facts and thoughts that support the idea that p73 could still be a tumor suppressor gene. The tumor suppressor network in which p73 appears to be a participant involves E2F1, JunB, INK4a/p16, ARF/p19, p57kip2 and BRCA1. Knock out of each gene in E2F-1-p73-JunB-p16INK4a network of tumor suppressor proteins result in lymphoma/leukemia formation. Further, I tried to explain why lymphomas are not seen in p73 null mice and why p73 gene is not prone to frequent mutation.

  8. Multiplexed Methylation Profiles of Tumor Suppressor Genes in Bladder Cancer

    Science.gov (United States)

    Cabello, Maria José; Grau, Laura; Franco, Noreli; Orenes, Esteban; Alvarez, Miguel; Blanca, Ana; Heredero, Oscar; Palacios, Alberto; Urrutia, Manuel; Fernández, Jesus María; López-Beltrán, Antonio; Sánchez-Carbayo, Marta

    2011-01-01

    Changes in DNA methylation of tumor suppressors can occur early in carcinogenesis and are potentially important early indicators of cancer. The objective of this study was to assess the methylation of 25 tumor suppressor genes in bladder cancer using a methylation-specific (MS) multiplex ligation-dependent probe amplification assay (MLPA). Initial analyses in bladder cancer cell lines (n = 14) and fresh-frozen primary bladder tumor specimens (n = 31) supported the panel of genes selected being altered in bladder cancer. The process of MS-MLPA was optimized for its application in body fluids using two independent training and validation sets of urinary specimens (n = 146), including patients with bladder cancer (n = 96) and controls (n = 50). BRCA1 (71.0%), WT1 (38.7%), and RARB (38.7%) were the most frequently methylated genes in bladder tumors, with WT1 methylation being significantly associated with tumor stage (P = 0.011). WT1 and PAX5A were identified as methylated tumor suppressors. In addition, BRCA1, WT1, and RARB were the most frequently methylated genes in urinary specimens. Receiver operating characteristic curve analyses revealed significant diagnostic accuracies in both urinary sets for BRCA1, RARB, and WT1. The novelty of this report relates to applying MS-MLPA, a multiplexed methylation technique, for tumor suppressors in bladder cancer and body fluids. Methylation profiles of tumor suppressor genes were clinically relevant for histopathological stratification of bladder tumors and offered a noninvasive diagnostic strategy for the clinical management of patients affected with uroepithelial neoplasias. PMID:21227392

  9. FOXO3 – A Major Gene for Human Longevity

    Science.gov (United States)

    Morris, Brian J.; Willcox, D. Craig; Donlon, Timothy A.; Willcox, Bradley J.

    2015-01-01

    Background The gene FOXO3, encoding the transcription factor forkhead box O-3 (FoxO3), is one of only two for which genetic polymorphisms have exhibited consistent associations with longevity in diverse human populations. Objective Here we review the multitude of actions of FoxO3 that are relevant to health, and thus healthy ageing and longevity. Methods Literature search for articles retrieved from PubMed using FoxO3 as keyword. Results We review the molecular genetics of FOXO3 in longevity, then current knowledge of FoxO3 function relevant to ageing and lifespan. We describe how FoxOs are involved in energy metabolism, oxidative stress, proteostasis, apoptosis, cell cycle regulation, metabolic processes, immunity, inflammation and stem cell maintenance. The single FoxO in Hydra confers immortality to this fresh water polyp, but as more complex organisms evolved this role has been usurped by the need for FoxO to control a broader range of specialized pathways across a wide spectrum of tissues assisted by the advent of as many as 4 FoxO subtypes in mammals. The major themes of FoxO3 are similar, but not identical, to other FoxOs and include regulation of cellular homeostasis, particularly of stem cells, and of inflammation, which is a common theme of age-related diseases. Other functions concern metabolism, cell cycle arrest, apoptosis, destruction of potentially damaging reactive oxygen species, and proteostasis. Conclusions The mechanism by which longevity-associated alleles of FOXO3 reduce age-related mortality is currently of great clinical interest. The prospect of optimizing FoxO3 activity in humans to increase lifespan and reduce age-related diseases represents an exciting avenue of clinical investigation. Research strategies directed at developing therapeutic agents that target FoxO3, its gene and proteins in the pathway(s) FoxO3 regulates should be encouraged and supported. PMID:25832544

  10. Tumor-Induced Myeloid-Derived Suppressor Cells.

    Science.gov (United States)

    De Sanctis, Francesco; Bronte, Vincenzo; Ugel, Stefano

    2016-06-01

    Myeloid-derived suppressor cells (MDSCs) represent a heterogeneous, immune-suppressive leukocyte population that develops systemically and infiltrates tumors. MDSCs can restrain the immune response through different mechanisms including essential metabolite consumption, reactive oxygen and nitrogen species production, as well as display of inhibitory surface molecules that alter T-cell trafficking and viability. Moreover, MDSCs play a role in tumor progression, acting directly on tumor cells and promoting cancer stemness, angiogenesis, stroma deposition, epithelial-to-mesenchymal transition, and metastasis formation. Many biological and pharmaceutical drugs affect MDSC expansion and functions in preclinical tumor models and patients, often reversing host immune dysfunctions and allowing a more effective tumor immunotherapy.

  11. Tumor Suppressor Genes: A Key to the Cancer Puzzle?

    Science.gov (United States)

    Oppenheimer, Steven B.

    1991-01-01

    Author describes developments in understanding of tumor suppressor genes or antioncogenes that he feels is most important breakthrough in solving cancer problem. Describes 1969 starting work of Harris with mouse fibroblast genes and later work of Knudson with retinoblastoma cells. Provides evidence that deletion of chromosome that results in the…

  12. "Ring-fencing" BRCA1 tumor suppressor activity.

    Science.gov (United States)

    Patel, Ketan J; Crossan, Gerry P; Hodskinson, Michael R G

    2011-12-13

    BRCA1 is a crucial human breast and ovarian cancer tumor suppressor gene. The article by Drost et al. in this issue of Cancer Cell together with a recent paper in Science now provide a clearer picture of how this large and complex protein suppresses tumorigenesis.

  13. Involvement of the JNK/FOXO3a/Bim Pathway in Neuronal Apoptosis after Hypoxic-Ischemic Brain Damage in Neonatal Rats.

    Directory of Open Access Journals (Sweden)

    Deyuan Li

    Full Text Available c-Jun N-terminal kinase (JNK plays a key role in the regulation of neuronal apoptosis. Previous studies have revealed that forkhead transcription factor (FOXO3a is a critical effector of JNK-mediated tumor suppression. However, it is not clear whether the JNK/FOXO3a pathway is involved in neuronal apoptosis in the developing rat brain after hypoxia-ischemia (HI. In this study, we generated an HI model using postnatal day 7 rats. Fluorescence immunolabeling and Western blot assays were used to detect the distribution and expression of total and phosphorylated JNK and FOXO3a and the pro-apoptotic proteins Bim and CC3. We found that JNK phosphorylation was accompanied by FOXO3a dephosphorylation, which induced FOXO3a translocation into the nucleus, resulting in the upregulation of levels of Bim and CC3 proteins. Furthermore, we found that JNK inhibition by AS601245, a specific JNK inhibitor, significantly increased FOXO3a phosphorylation, which attenuated FOXO3a translocation into the nucleus after HI. Moreover, JNK inhibition downregulated levels of Bim and CC3 proteins, attenuated neuronal apoptosis and reduced brain infarct volume in the developing rat brain. Our findings suggest that the JNK/FOXO3a/Bim pathway is involved in neuronal apoptosis in the developing rat brain after HI. Agents targeting JNK may offer promise for rescuing neurons from HI-induced damage.

  14. Caffeine activates tumor suppressor PTEN in sarcoma cells

    OpenAIRE

    Miwa, Shinji; Sugimoto, Naotoshi; Shirai, Toshiharu; Hayashi, Katsuhiro; Nishida, Hideji; Ohnari, Issei; Takeuchi, Akihiko; Yachie, Akihiro; Tsuchiya, Hiroyuki

    2011-01-01

    The tumor suppressor phosphatase and tensin homolog deleted on chromosome 10 (PTEN) is a negative regulator of the phosphatidylinositol 3-kinase (PI3K)/Akt signaling pathway. Akt activation exerts a strong anti-apoptotic effect and inhibits key pro-apoptotic proteins. We investigated the effect of caffeine in the prevention of tumor cell proliferation and induction of cell death. We found that caffeine induced increased intracellular cAMP levels, PTEN activation and Akt inactivation, which to...

  15. Enhanced transfection of brain tumor suppressor genes by photochemical internalization

    Science.gov (United States)

    Chou, Chih H.; Sun, Chung-Ho; Zhou, Yi-Hong; Madsen, Steen J.; Hirschberg, Henry

    2011-03-01

    One of many limitations for cancer gene therapy is the inability of the therapeutic gene to transfect a sufficient number of tumor cells. Photochemical internalization (PCI) is a photodynamic therapy-based approach for improving the delivery of macromolecules and genes into the cell cytosol. The utility of PCI for the delivery of a tumor suppressor gene (PAX-6) was investigated in monolayers and spheroids consisting of F98 rat glioma cells.

  16. Multiplicity of acquired cross-resistance in paclitaxel-resistant cancer cells is associated with feedback control of TUBB3 via FOXO3a-mediated ABCB1 regulation

    Science.gov (United States)

    Aldonza, Mark Borris D.; Hong, Ji-Young; Alinsug, Malona V.; Song, Jayoung; Lee, Sang Kook

    2016-01-01

    Acquired drug resistance is a primary obstacle for effective cancer therapy. The correlation of point mutations in class III β-tubulin (TUBB3) and the prominent overexpression of ATP-binding cassette P-glycoprotein (ABCB1), a multidrug resistance gene, have been protruding mechanisms of resistance to microtubule disruptors such as paclitaxel (PTX) for many cancers. However, the precise underlying mechanism of the rapid onset of cross-resistance to an array of structurally and functionally unrelated drugs in PTX-resistant cancers has been poorly understood. We determined that our established PTX-resistant cancer cells display ABCB1/ABCC1-associated cross-resistance to chemically different drugs such as 5-fluorouracil, docetaxel, and cisplatin. We found that feedback activation of TUBB3 can be triggered through the FOXO3a-dependent regulation of ABCB1, which resulted in the accentuation of induced PTX resistance and encouraged multiplicity in acquired cross-resistance. FOXO3a-directed regulation of P-glycoprotein (P-gp) function suggests that control of ABCB1 involves methylation-dependent activation. Consistently, transcriptional overexpression or downregulation of FOXO3a directs inhibitor-controlled protease-degradation of TUBB3. The functional PI3K/Akt signaling is tightly responsive to FOXO3a activation alongside doxorubicin treatment, which directs FOXO3a arginine hypermethylation. In addition, we found that secretome factors from PTX-resistant cancer cells with acquired cross-resistance support a P-gp-dependent association in multidrug resistance (MDR) development, which assisted the FOXO3a-mediated control of TUBB3 feedback. The direct silencing of TUBB3 reverses induced multiple cross-resistance, reduces drug-resistant tumor mass, and suppresses the impaired microtubule stability status of PTX-resistant cells with transient cross-resistance. These findings highlight the control of the TUBB3 response to ABCB1 genetic suppressors as a mechanism to reverse the

  17. Isolation of tumor suppressor genes from MEN-1 related neoplasms

    Energy Technology Data Exchange (ETDEWEB)

    Yavari, R.; Kinder, B.; Bale, A.E. [Yale Univ. School of Medicine, New Haven, CT (United States)

    1994-09-01

    Multiple Endocrine Neoplasia type 1 (MEN 1) is a cancer predisposition syndrome marked by the development of tumors in specific endocrine tissues such as the pituitary, parathyroid and pancreatic islets. Genetic linkage studies have mapped the MEN 1 gene to 11q13, and allelic loss in related tumors suggests that the gene is a tumor suppressor. Because inactivation of tumor suppressors may be accompanied by underexpression, subtractive hybridization was used to isolate potential candidate genes underexpressed in MEN 1 tumors. cDNA was synthesized from tumor and normal parathyroid tissue by RT-PCR. Biotinylated tumor cDNA was used as a driver and normal cDNA as a tester in subtractive hybridization. Following annealing of the driver and tester amplicons, the biotinylated strands were removed with streptavidin. The subtracted material was then used as a probe to isolate clones from a normal pancreatic islet library. Screening 2 x 10{sup 5} plaques yielded 14 positive clones. Of 6 clones analyzed, 3 were confirmed to be underexpressed in parathyroid tumors. Sequence analysis identified 2 clones as human ribosomal protein S10 (RPS10, chromosome 6) and 1 as the islet amyloid polypeptide (1AP, chromosome 12). The precise function of human RPS10 is not known but the related RPS6 functions as a tumor suppressor in Drosophila. 1AP has been implicated in modulation of G protein activity. The remaining positive clones will be mapped to determine if any fall on chromosome 11q13, and additional subtractions with parathyroid and pancreatic islet neoplasms are underway.

  18. Control of autophagy by oncogenes and tumor suppressor genes.

    Science.gov (United States)

    Maiuri, M C; Tasdemir, E; Criollo, A; Morselli, E; Vicencio, J M; Carnuccio, R; Kroemer, G

    2009-01-01

    Multiple oncogenes (in particular phosphatidylinositol 3-kinase, PI3K; activated Akt1; antiapoptotic proteins from the Bcl-2 family) inhibit autophagy. Similarly, several tumor suppressor proteins (such as BH3-only proteins; death-associated protein kinase-1, DAPK1; the phosphatase that antagonizes PI3K, PTEN; tuberous sclerosic complex 1 and 2, TSC1 and TSC2; as well as LKB1/STK11) induce autophagy, meaning that their loss reduces autophagy. Beclin-1, which is required for autophagy induction acts as a haploinsufficient tumor suppressor protein, and other essential autophagy mediators (such as Atg4c, UVRAG and Bif-1) are bona fide oncosuppressors. One of the central tumor suppressor proteins, p53 exerts an ambiguous function in the regulation of autophagy. Within the nucleus, p53 can act as an autophagy-inducing transcription factor. Within the cytoplasm, p53 exerts a tonic autophagy-inhibitory function, and its degradation is actually required for the induction of autophagy. The role of autophagy in oncogenesis and anticancer therapy is contradictory. Chronic suppression of autophagy may stimulate oncogenesis. However, once a tumor is formed, autophagy inhibition may be a therapeutic goal for radiosensitization and chemosensitization. Altogether, the current state-of-the art suggests a complex relationship between cancer and deregulated autophagy that must be disentangled by further in-depth investigation.

  19. Inactivation of X-linked tumor suppressor genes in human cancer.

    Science.gov (United States)

    Liu, Runhua; Kain, Mandy; Wang, Lizhong

    2012-04-01

    Cancer cells silence autosomal tumor suppressor genes by Knudson's two-hit mechanism in which loss-of-function mutations and then loss of heterozygosity occur at the tumor suppressor gene loci. However, the identification of X-linked tumor suppressor genes has challenged the traditional theory of 'two-hit inactivation' in tumor suppressor genes, introducing the novel concept that a single genetic hit can cause loss of tumor suppressor function. The mechanism through which these genes are silenced in human cancer is unclear, but elucidating the details will greatly enhance our understanding of the pathogenesis of human cancer. Here, we review the identification of X-linked tumor suppressor genes and discuss the potential mechanisms of their inactivation. In addition, we also discuss how the identification of X-linked tumor suppressor genes can potentially lead to new approaches in cancer therapy.

  20. Functional Study of the Human BRCA2 Tumor Suppressor

    Science.gov (United States)

    2005-08-01

    Wang, Y., Lee, M. & Venkitaraman, A. R. Abnormal cytokinesis in cells deficient in the breast cancer susceptibility protein BRCA2. Science 306, 876...tumor suppressor genes in mitotic and meiotic cells. Mol Cell 2, 317-28 (1998). 28. Fuks, F., Milner, J. & Kouzarides, T. BRCA2 associates with...Scully, R. et al. Association of BRCA1 with Rad5l in mitotic and meiotic cells. Cell 88, 265-75 (1997). 49. Nakanishi, K. et al. Human Fanconi anemia

  1. BRCA1 tumor suppressor network: focusing on its tail

    Directory of Open Access Journals (Sweden)

    Wang Bin

    2012-02-01

    Full Text Available Abstract Germline mutations of the BRCA1 tumor suppressor gene are a major cause of familial breast and ovarian cancer. BRCA1 plays critical roles in the DNA damage response that regulates activities of multiple repair and checkpoint pathways for maintaining genome stability. The BRCT domains of BRCA1 constitute a phospho-peptide binding domain recognizing a phospho-SPxF motif (S, serine; P, proline; × varies; F, phenylalanine. The BRCT domains are frequently targeted by clinically important mutations and most of these mutations disrupt the binding surface of the BRCT domains to phosphorylated peptides. The BRCT domain and its capability to bind phosphorylated protein is required for the tumor suppressor function of BRCA1. Through its BRCT phospho-binding ability BRCA1 forms at least three mutually exclusive complexes by binding to phosphorylated proteins Abraxas, Bach1 and CTIP. The A, B and C complexes, at lease partially undertake BRCA1's role in mechanisms of cell cycle checkpoint and DNA repair that maintain genome stability, thus may play important roles in BRCA1's tumor suppressor function.

  2. The ING tumor suppressors in cellular senescence and chromatin.

    Science.gov (United States)

    Ludwig, Susann; Klitzsch, Alexandra; Baniahmad, Aria

    2011-07-18

    The Inhibitor of Growth (ING) proteins represent a type II tumor suppressor family comprising five conserved genes, ING1 to ING5. While ING1, ING2 and ING3 proteins are stable components of the mSIN3a-HDAC complexes, the association of ING1, ING4 and ING5 with HAT protein complexes was also reported. Among these the ING1 and ING2 have been analyzed more deeply. Similar to other tumor suppressor factors the ING proteins are also involved in many cellular pathways linked to cancer and cell proliferation such as cell cycle regulation, cellular senescence, DNA repair, apoptosis, inhibition of angiogenesis and modulation of chromatin.A common structural feature of ING factors is the conserved plant homeodomain (PHD), which can bind directly to the histone mark trimethylated lysine of histone H3 (H3K4me3). PHD mutants lose the ability to undergo cellular senescence linking chromatin mark recognition with cellular senescence. ING1 and ING2 are localized in the cell nucleus and associated with chromatin modifying enzymes, linking tumor suppression directly to chromatin regulation. In line with this, the expression of ING1 in tumors is aberrant or identified point mutations are mostly localized in the PHD finger and affect histone binding. Interestingly, ING1 protein levels increase in replicative senescent cells, latter representing an efficient pathway to inhibit cancer proliferation. In association with this, suppression of p33ING1 expression prolongs replicative life span and is also sufficient to bypass oncogene-induced senescence. Recent analyses of ING1- and ING2-deficient mice confirm a tumor suppressive role of ING1 and ING2 and also indicate an essential role of ING2 in meiosis.Here we summarize the activity of ING1 and ING2 as tumor suppressors, chromatin factors and in development.

  3. Knockdown of FOXO3 induces primordial oocyte activation in pigs.

    Science.gov (United States)

    Moniruzzaman, Mohammad; Lee, Jibak; Zengyo, Mai; Miyano, Takashi

    2010-02-01

    Mammalian ovaries are endowed with a large number of primordial follicles, each containing a nongrowing oocyte. Only a small population of primordial oocytes (oocytes in primordial follicles) is activated to enter the growth phase throughout a female's reproductive life. Little is known about the mechanism regulating the activation of primordial oocytes. Here, we found that the primordial oocytes from infant pigs (10- to 20-day-old) grew to full size at 2 months after xenografting to immunodeficient mice, whereas those from prepubertal pigs (6-month-old) survived without initiation of their growth even after 4 months; thereafter, they started to grow and reached full size after 6 months. These results suggest that the mechanism regulating the activation of primordial oocytes in prepubertal pigs is different from that in infant pigs. In this regard, the involvement of FOXO3, a forkhead transcription factor, was studied. In prepubertal pigs, FOXO3 was detected in almost all (94+/-2%) primordial oocyte nuclei, and in infant pigs, 42+/-7% primordial oocytes were FOXO3 positive. At 4 months after xenografting, the percentage of FOXO3-positive primordial oocytes from prepubertal pigs had decreased to the infant level. Further, siRNA was designed to knock down porcine FOXO3. FOXO3-knockdown primordial follicles from prepubertal pigs developed to the antral stage accompanied by oocyte growth at 2 months after xenografting. These results suggest that primordial oocytes are dormant in prepubertal pigs by a FOXO3-related mechanism to establish a nongrowing oocyte pool in the ovary, and that a transient knockdown of the FOXO3 activates the primordial oocytes to enter the growth phase.

  4. Role of tumor suppressor genes in transplacental lung carcinogenesis.

    Science.gov (United States)

    Rollins, L A; Leone-Kabler, S; O'Sullivan, M G; Miller, M S

    1998-03-01

    Most human cancers involve multiple genetic changes, including activation of oncogenes such as Ki-ras-2 (Kras2) and inactivation of any one of a number of tumor suppressor genes such as p53 and members of the retinoblastoma (Rb) regulatory axis. As part of an ongoing project to determine how in utero exposure to chemical carcinogens affects the molecular pathogenesis of murine lung tumors, the p53 and p16Cdkn2a genes were analyzed by using paraffin-embedded lung tissues from mice treated transplacentally with 3-methylcholanthrene. Single-strand conformation polymorphism analysis of exons 5-8 of the p53 gene, as well as their flanking introns, demonstrated an absence of mutations at this gene locus. However, a genetic polymorphism was identified at nt 708 in intron 4 of the DBA/2 strain of mice 5 bp downstream of a 3' branching-point splice signal. Analysis of exons 1 and 2 of the Cdkn2a gene by single-strand conformation polymorphism and sequence analyses revealed mutations in exon 2 in 7% of the tumors examined. Tumor 23-1 exhibited a CAC-->TAC transition at nt 301 (His74-->Tyr74), and tumor 36-1 exhibited a GGG-->GAG transition at nucleotide 350 (Gly90-->Glu90). Northern blot analysis of 14 of the larger tumors showed a marked decrease in the levels of Rb RNA expression. Immunohistochemical analysis revealed a spectrum of pRb expression, with the smaller adenomas showing moderate numbers of nuclei with heterogeneous staining for pRb in contrast with a highly reduced or near-complete absence of expression in the nuclei of larger tumors with features of adenocarcinomas. The low incidence of mutations at tumor suppressor loci suggested that inactivation of tumor suppressor genes was a late event in murine lung tumor pathogenesis. The identification of both mutations at the Cdkn2a gene locus and reduced levels of Rb expression combined with previous studies demonstrating a high incidence of mutated Kras2 alleles in these tumors implies that alterations of the Rb

  5. Tumor suppressor p53 meets microRNAs

    OpenAIRE

    2011-01-01

    Tumor suppressor p53 plays a central role in tumor prevention. As a transcription factor, p53 mainly exerts its function through transcription regulation of its target genes to initiate various cellular responses. To maintain its proper function, p53 is tightly regulated by a wide variety of regulators in cells. Thus, p53, its regulators and regulated genes form a complex p53 network which is composed of hundreds of genes and their products. microRNAs (miRNAs) are a class of endogenously expr...

  6. The new research on tumor suppressor gene in hepatocellular carcinoma

    Institute of Scientific and Technical Information of China (English)

    JI Yu-bin; YANG Hai-fan; YU Lei; PANG lin-lin; LI Hai-jiao; LIU Guang-da

    2008-01-01

    Hepatocellular carcinoma (HCC) is one of the leading causes of cancer-related death in the world. The carcinogenesis of HCC is multifactorial, multifunctional and multistage. Tumor suppressor gene therapy is one of the strategies, it is mainly used to make use of tumor suppressor gene groups which can inhibit the cell growth, to prevent the expression of oncogenes or to resume the function of anti-oncogenes. But so far, there is not a particular gene to be a main tumor suppressor gene in HCC. Therefore, it is necessary to study on the new anti-oncogenes to explain pathogenesis of liver cancer and seek for the newly effective target to carry on liver cancer gene therapy. PTEN (phosphatase and tensin homolog deleted on chromosome ten) was discovered as a tumor suppressor gene. It functions as a protein tyrosine phosphatase and as a lipid phosphatase. As a lipid phosphatase, PTEN antagonizes PI3K/Akt signaling by dephosphorylating the D3 position of the inositol ring of phosphatidylinositol 3, 4, 5-trisphosphate(PIP3), to generate phosphatidylinositol-4, 5,- biphosphate(PIP2). On the other hand, as a protein tyrosine phosphatase, PTEN can dephosphorylate itself, focal adhesion kinase (FAK) and the platelet derived growth factor receptor, involves in the migration, adhension of cells. Many researches have been testified that there is a higher frequency of negative expression of PTEN protein in hepatocellular carcinoma, the negative correlation between expression of PTEN gene and differential grade, clinic stage of HCC indicated that in activation of PTEN gene maybe a late incidence in the development of hepatocellular carcinoma and may play an important role in the genesis and development of some hepatocellular carcinoma. KLF6, a member of Krupple-like gene family, a ubiquitously expressed zinc finger transcription factor, has an important role in regulating cell growth and differentiation. Several experiments have been proved that the genetic events of tumor

  7. The tumor suppressor ARF regulates innate immune responses in mice.

    Science.gov (United States)

    Través, Paqui G; López-Fontal, Raquel; Luque, Alfonso; Hortelano, Sonsoles

    2011-12-15

    The innate immune system is the first line of defense against invading organisms, and TLRs are the main sensors of microbial components, initiating signaling pathways that induce the production of proinflammatory cytokines and type I IFNs. An antiviral action for the tumor suppressor alternative reading frame (ARF) has been reported; however, the precise role of ARF in innate immunity is unknown. In this study, we show that ARF plays an important role in regulation of inflammatory responses. In peritoneal macrophages and bone marrow-derived macrophages from ARF-deficient animals, the induction of proinflammatory cytokines and chemokines by TLR ligands was severely impaired. The altered responses of ARF(-/-) cells to TLR ligands result from aberrant activation of intracellular signaling molecules including MAPKs, IκBα degradation, and NF-κB activation. Additionally, animals lacking ARF were resistant to LPS-induced endotoxic shock. This impaired activation of inflammation in ARF(-/-) mice was not restricted to TLRs, as it was also shown in response to non-TLR signaling pathways. Thus, ARF(-/-) mice were also unable to trigger a proper inflammatory response in experimental peritonitis or in 12-O-tetradecanoylphorbol-13-acetate-induced edema. Overexpression of ARF, but not its downstream target p53, rescued the ARF-deficient phenotype, increasing TLR4 levels and restoring inflammatory reaction. An increase in the E2F1 protein levels observed in ARF(-/-) macrophages at basal condition and after LPS stimulation may be involved in the impaired response in this system, as E2F1 has been described as an inflammatory suppressor. These results indicate that tumor suppressor ARF is a new regulator of inflammatory cell signaling.

  8. RB1: a prototype tumor suppressor and an enigma.

    Science.gov (United States)

    Dyson, Nicholas J

    2016-07-01

    The retinoblastoma susceptibility gene (RB1) was the first tumor suppressor gene to be molecularly defined. RB1 mutations occur in almost all familial and sporadic forms of retinoblastoma, and this gene is mutated at variable frequencies in a variety of other human cancers. Because of its early discovery, the recessive nature of RB1 mutations, and its frequency of inactivation, RB1 is often described as a prototype for the class of tumor suppressor genes. Its gene product (pRB) regulates transcription and is a negative regulator of cell proliferation. Although these general features are well established, a precise description of pRB's mechanism of action has remained elusive. Indeed, in many regards, pRB remains an enigma. This review summarizes some recent developments in pRB research and focuses on progress toward answers for the three fundamental questions that sit at the heart of the pRB literature: What does pRB do? How does the inactivation of RB change the cell? How can our knowledge of RB function be exploited to provide better treatment for cancer patients?

  9. Transcriptional Regulation of the p16 Tumor Suppressor Gene.

    Science.gov (United States)

    Kotake, Yojiro; Naemura, Madoka; Murasaki, Chihiro; Inoue, Yasutoshi; Okamoto, Haruna

    2015-08-01

    The p16 tumor suppressor gene encodes a specific inhibitor of cyclin-dependent kinase (CDK) 4 and 6 and is found altered in a wide range of human cancers. p16 plays a pivotal role in tumor suppressor networks through inducing cellular senescence that acts as a barrier to cellular transformation by oncogenic signals. p16 protein is relatively stable and its expression is primary regulated by transcriptional control. Polycomb group (PcG) proteins associate with the p16 locus in a long non-coding RNA, ANRIL-dependent manner, leading to repression of p16 transcription. YB1, a transcription factor, also represses the p16 transcription through direct association with its promoter region. Conversely, the transcription factors Ets1/2 and histone H3K4 methyltransferase MLL1 directly bind to the p16 locus and mediate p16 induction during replicative and premature senescence. In the present review, we discuss the molecular mechanisms by which these factors regulate p16 transcription.

  10. TANGO is a tumor suppressor of malignant melanoma.

    Science.gov (United States)

    Arndt, Stephanie; Bosserhoff, Anja K

    2006-12-15

    The TANGO gene was originally identified as a new family member of the melanoma inhibitory activity gene family. The gene codes for a 14 kDa protein of so far unknown function. In our study we revealed that TANGO was downregulated or lost in 9 melanoma cell lines when compared to normal melanocytes and in most of the 8 tumor samples analyzed. The losses were associated with advanced stage of the disease. These results were confirmed in situ by immunohistochemistry on 10 paraffin-embedded sections of human malignant melanoma primary tumors and melanoma skin metastases. A small reduction of TANGO was also seen in different benign and atypical nevi when compared to normal skin. For functional analysis of TANGO we evaluated TANGO re-expressing melanoma cell clones and antisense TANGO cell clones with a complete loss of TANGO. Functional assays with TANGO transfected or treated cell lines revealed that TANGO expression reduces motility, whereas reduction of TANGO enhances migration. Our studies, therefore, indicate that reduction of TANGO expression contributes to tumor progression. These results taken together provide the first indications for a tumor suppressor role of TANGO gene in human malignant melanoma.

  11. Cellular senescence and tumor suppressor gene p16.

    Science.gov (United States)

    Rayess, Hani; Wang, Marilene B; Srivatsan, Eri S

    2012-04-15

    Cellular senescence is an irreversible arrest of cell growth. Biochemical and morphological changes occur during cellular senescence, including the formation of a unique cellular morphology such as flattened cytoplasm. Function of mitochondria, endoplasmic reticulum and lysosomes are affected resulting in the inhibition of lysosomal and proteosomal pathways. Cellular senescence can be triggered by a number of factors including, aging, DNA damage, oncogene activation and oxidative stress. While the molecular mechanism of senescence involves p16 and p53 tumor suppressor genes and telomere shortening, this review is focused on the mechanism of p16 control. The p16-mediated senescence acts through the retinoblastoma (Rb) pathway inhibiting the action of the cyclin dependant kinases leading to G1 cell cycle arrest. Rb is maintained in a hypophosphorylated state resulting in the inhibition of transcription factor E2F1. Regulation of p16 expression is complex and involves epigenetic control and multiple transcription factors. PRC1 (Pombe repressor complex (1) and PRC2 (Pombe repressor complex (2) proteins and histone deacetylases play an important role in the promoter hypermethylation for suppressing p16 expression. While transcription factors YY1 and Id1 suppress p16 expression, transcription factors CTCF, Sp1 and Ets family members activate p16 transcription. Senescence occurs with the inactivation of suppressor elements leading to the enhanced expression of p16. Copyright © 2011 UICC.

  12. Classical Oncogenes and Tumor Suppressor Genes: A Comparative Genomics Perspective

    Directory of Open Access Journals (Sweden)

    Oxana K. Pickeral

    2000-05-01

    Full Text Available We have curated a reference set of cancer-related genes and reanalyzed their sequences in the light of molecular information and resources that have become available since they were first cloned. Homology studies were carried out for human oncogenes and tumor suppressors, compared with the complete proteome of the nematode, Caenorhabditis elegans, and partial proteomes of mouse and rat and the fruit fly, Drosophila melanogaster. Our results demonstrate that simple, semi-automated bioinformatics approaches to identifying putative functionally equivalent gene products in different organisms may often be misleading. An electronic supplement to this article1 provides an integrated view of our comparative genomics analysis as well as mapping data, physical cDNA resources and links to published literature and reviews, thus creating a “window” into the genomes of humans and other organisms for cancer biology.

  13. Oncogenes, protooncogenes, and tumor suppressor genes in acute myelogenous leukemia.

    Science.gov (United States)

    Hijiya, N; Gewirtz, A M

    1995-05-01

    In recent years, our understanding of normal human hematopoiesis has expanded greatly. We have increased our knowledge of regulatory growth factors, the receptors through which they act, and the secondary messengers involved in transducing the growth/differentiation signals from the cytoplasmic membrane to the nucleus. This knowledge has revealed potential mechanisms for inducing the neoplastic transformation of hematopoietic cells. This applies in particular to the role of viral oncogenes and cellular protooncogenes and, more recently, to the role of tumor suppressor genes. Protooncogenes are intimately involved in the processes of cell proliferation and differentiation. Therefore, any amplification, mutation, structural alteration, or change in transcriptional regulation of protooncogenes might lead to or be associated with induction of the malignant phenotype. Based on the importance of these genes in leukemogenesis and the maintenance of the malignant phenotype, it seems reasonable to hypothesize that targeted disruption of leukemogenic genes may be of therapeutic value.

  14. The human ARF tumor suppressor senses blastema activity and suppresses epimorphic tissue regeneration.

    Science.gov (United States)

    Hesse, Robert G; Kouklis, Gayle K; Ahituv, Nadav; Pomerantz, Jason H

    2015-11-17

    The control of proliferation and differentiation by tumor suppressor genes suggests that evolution of divergent tumor suppressor repertoires could influence species' regenerative capacity. To directly test that premise, we humanized the zebrafish p53 pathway by introducing regulatory and coding sequences of the human tumor suppressor ARF into the zebrafish genome. ARF was dormant during development, in uninjured adult fins, and during wound healing, but was highly expressed in the blastema during epimorphic fin regeneration after amputation. Regenerative, but not developmental signals resulted in binding of zebrafish E2f to the human ARF promoter and activated conserved ARF-dependent Tp53 functions. The context-dependent activation of ARF did not affect growth and development but inhibited regeneration, an unexpected distinct tumor suppressor response to regenerative versus developmental environments. The antagonistic pleiotropic characteristics of ARF as both tumor and regeneration suppressor imply that inducing epimorphic regeneration clinically would require modulation of ARF -p53 axis activation.

  15. Germline promoter hypermethylation of tumor suppressor genes in gastric cancer

    Institute of Scientific and Technical Information of China (English)

    Pu-Yuan Wu; Zheng Zhang; Jing-Mei Wang; Wen-Wen Guo; Nong Xiao; Qiong He; Ya-Ping Wang; Yi-Mei Fan

    2012-01-01

    AIM: To explore germline hypermethylation of the tumor suppressor genes MLH1 , CDH1 and P16INK4a in suspected cases of hereditary gastric cancer (GC). METHODS: A group of 140 Chinese GC patients in whom the primary cancer had developed before the age of 60 or who had a familial history of cancer were screened for germline hypermethylation of the MLH1 , CDH1 and P16INK4a tumor suppressor genes. Genomic DNA was extracted from peripheral blood leukocytes and modified by sodium bisulfite. The treated DNA was then subjected to bisulfite DNA sequencing for a specific region of the MLH1 promoter. The methylation status of CDH1 or P16INK4a was assayed using methylation- specific PCR. Clonal bisulfite allelic sequencing in positive samples was performed to obtain a comprehensive analysis of the CpG island methylation status of these promoter regions. RESULTS: Methylation of the MLH1 gene promoter was detected in the peripheral blood DNA of only 1/140 (0.7%) of the GC patient group. However, this methylation pattern was mosaic rather than the allelic pattern which has previously been reported for MLH1 in hereditary non-polyposis colorectal cancer (HNPCC) patients. We found that 10% of the MLH1 alleles in the peripheral blood DNA of this patient were methylated, consistent with 20% of cells having one methylated allele. No germline promoter methylation of the CDH1 or P16INK4a genes was detected. CONCLUSION: Mosaic germline epimutation of the MLH1 gene is present in suspected hereditary GC patients in China but at a very low level. Germline epimutation of the CDH1 or P16INK4a gene is not a frequent event.

  16. Metastasis Suppressors Regulate the Tumor Microenvironment by Blocking Recruitment of Prometastatic Tumor-Associated Macrophages.

    Science.gov (United States)

    Frankenberger, Casey; Rabe, Daniel; Bainer, Russell; Sankarasharma, Devipriya; Chada, Kiran; Krausz, Thomas; Gilad, Yoav; Becker, Lev; Rosner, Marsha Rich

    2015-10-01

    Triple-negative breast cancer (TNBC) patients have the highest risk of recurrence and metastasis. Because they cannot be treated with targeted therapies, and many do not respond to chemotherapy, they represent a clinically underserved group. TNBC is characterized by reduced expression of metastasis suppressors such as Raf kinase inhibitory protein (RKIP), which inhibits tumor invasiveness. Mechanisms by which metastasis suppressors alter tumor cells are well characterized; however, their ability to regulate the tumor microenvironment and the importance of such regulation to metastasis suppression are incompletely understood. Here, we use species-specific RNA sequencing to show that RKIP expression in tumors markedly reduces the number and metastatic potential of infiltrating tumor-associated macrophages (TAM). TAMs isolated from nonmetastatic RKIP(+) tumors, relative to metastatic RKIP(-) tumors, exhibit a reduced ability to drive tumor cell invasion and decreased secretion of prometastatic factors, including PRGN, and shed TNFR2. RKIP regulates TAM recruitment by blocking HMGA2, resulting in reduced expression of numerous macrophage chemotactic factors, including CCL5. CCL5 overexpression in RKIP(+) tumors restores recruitment of prometastatic TAMs and intravasation, whereas treatment with the CCL5 receptor antagonist Maraviroc reduces TAM infiltration. These results highlight the importance of RKIP as a regulator of TAM recruitment through chemokines such as CCL5. The clinical significance of these interactions is underscored by our demonstration that a signature comprised of RKIP signaling and prometastatic TAM factors strikingly separates TNBC patients based on survival outcome. Collectively, our findings identify TAMs as a previously unsuspected mechanism by which the metastasis-suppressor RKIP regulates tumor invasiveness, and further suggest that TNBC patients with decreased RKIP activity and increased TAM infiltration may respond to macrophage

  17. Tumor suppressors in Zebrafish : From TP53 to PTEN and beyond

    NARCIS (Netherlands)

    den Hertog, Jeroen

    2016-01-01

    Zebrafish are increasingly being used to study cancer. Almost all tumor types have been found in zebrafish. However, tumor incidence is relatively low and tumors develop late in life. Functional inactivation of tumor suppressors is a crucial step in cancer progression and more and more tumor

  18. Tumor Suppressors in Zebrafish : From TP53 to PTEN and Beyond

    NARCIS (Netherlands)

    den Hertog, Jeroen

    2016-01-01

    Zebrafish are increasingly being used to study cancer. Almost all tumor types have been found in zebrafish. However, tumor incidence is relatively low and tumors develop late in life. Functional inactivation of tumor suppressors is a crucial step in cancer progression and more and more tumor

  19. Tumor suppressors in Zebrafish : From TP53 to PTEN and beyond

    NARCIS (Netherlands)

    den Hertog, Jeroen

    2016-01-01

    Zebrafish are increasingly being used to study cancer. Almost all tumor types have been found in zebrafish. However, tumor incidence is relatively low and tumors develop late in life. Functional inactivation of tumor suppressors is a crucial step in cancer progression and more and more tumor suppres

  20. The tumor suppressor kinase LKB1: lessons from mouse models

    Institute of Scientific and Technical Information of China (English)

    Saara Ollila; Tomi P. M(a)kel(a)

    2011-01-01

    Mutations in the tumor suppressor gene LKB1 are important in hereditary Peutz-Jeghers syndrome,as well as in sporadic cancers including lung and cervical cancer.LKB1 is a kinase-activating Kinase,and a number of LKB1-dependent phosphorylation cascades regulate fundamental cellular and organismal processes in at least metabolism,polarity,cytoskeleton organization,and proliferation.Conditional targeting approaches are beginning to demonstrate the relevance and specificity of these signaling pathways in development and homeostasis of multiple organs.More than one of the pathways also appear to contribute to tumor growth following Lkb1 deficiencies based on a number of mouse tumor models.Lkb1-dependent activation of AMPK and subsequent inactivation of mammalian target of rapamycin signaling are implicated in several of the models,and other less well characterized pathways are also involved.Conditional targeting studies of Lkb1 also point an important role of LKB1 in epithelial-masenchymal interactions,significantly expanding knowledge on the relevance of LKB1 in human disease.

  1. Vitamin D receptor, a tumor suppressor in skin.

    Science.gov (United States)

    Bikle, Daniel D

    2015-05-01

    Vitamin D and calcium are well-established regulators of keratinocyte proliferation and differentiation. Therefore, it was not a great surprise that deletion of the vitamin D receptor (VDR) should predispose the skin to tumor formation, and that the combination of deleting both the VDR and calcium sensing receptor (CaSR) should be especially pro-oncogenic. In this review I have examined 4 mechanisms that appear to underlie the means by which VDR acts as a tumor suppressor in skin. First, DNA damage repair is curtailed in the absence of the VDR, allowing mutations in DNA to accumulate. Second and third involve the increased activation of the hedgehog and β-catenin pathways in the epidermis in the absence of the VDR, leading to poorly regulated proliferation with reduced differentiation. Finally, VDR deletion leads to a shift in the expression of long noncoding RNAs toward a more oncogenic profile. How these different mechanisms interact and their relative importance in the predisposition of the VDR null epidermis to tumor formation remain under active investigation.

  2. Notch1 functions as a tumor suppressor in mouse skin.

    Science.gov (United States)

    Nicolas, Michael; Wolfer, Anita; Raj, Kenneth; Kummer, J Alain; Mill, Pleasantine; van Noort, Mascha; Hui, Chi-chung; Clevers, Hans; Dotto, G Paolo; Radtke, Freddy

    2003-03-01

    Notch proteins are important in binary cell-fate decisions and inhibiting differentiation in many developmental systems, and aberrant Notch signaling is associated with tumorigenesis. The role of Notch signaling in mammalian skin is less well characterized and is mainly based on in vitro studies, which suggest that Notch signaling induces differentiation in mammalian skin. Conventional gene targeting is not applicable to establishing the role of Notch receptors or ligands in the skin because Notch1-/- embryos die during gestation. Therefore, we used a tissue-specific inducible gene-targeting approach to study the physiological role of the Notch1 receptor in the mouse epidermis and the corneal epithelium of adult mice. Unexpectedly, ablation of Notch1 results in epidermal and corneal hyperplasia followed by the development of skin tumors and facilitated chemical-induced skin carcinogenesis. Notch1 deficiency in skin and in primary keratinocytes results in increased and sustained expression of Gli2, causing the development of basal-cell carcinoma-like tumors. Furthermore, Notch1 inactivation in the epidermis results in derepressed beta-catenin signaling in cells that should normally undergo differentiation. Enhanced beta-catenin signaling can be reversed by re-introduction of a dominant active form of the Notch1 receptor. This leads to a reduction in the signaling-competent pool of beta-catenin, indicating that Notch1 can inhibit beta-catenin-mediated signaling. Our results indicate that Notch1 functions as a tumor-suppressor gene in mammalian skin.

  3. SIRT3: Oncogene and Tumor Suppressor in Cancer

    Directory of Open Access Journals (Sweden)

    Margalida Torrens-Mas

    2017-07-01

    Full Text Available Sirtuin 3 (SIRT3, the major deacetylase in mitochondria, plays a crucial role in modulating oxygen reactive species (ROS and limiting the oxidative damage in cellular components. SIRT3 targets different enzymes which regulate mitochondrial metabolism and participate in ROS detoxification, such as the complexes of the respiratory chain, the isocitrate dehydrogenase, or the manganese superoxide dismutase. Thus, SIRT3 activity is essential in maintaining mitochondria homeostasis and has recently received great attention, as it is considered a fidelity protein for mitochondrial function. In some types of cancer, SIRT3 functions as a tumoral promoter, since it keeps ROS levels under a certain threshold compatible with cell viability and proliferation. On the contrary, other studies describe SIRT3 as a tumoral suppressor, as SIRT3 could trigger cell death under stress conditions. Thus, SIRT3 could have a dual role in cancer. In this regard, modulation of SIRT3 activity could be a new target to develop more personalized therapies against cancer.

  4. Tumor suppressor p53 meets microRNAs

    Institute of Scientific and Technical Information of China (English)

    Zhaohui Feng; Cen Zhang; Rui Wu; Wenwei Hu

    2011-01-01

    Tumor suppressor p53 plays a central role in tumor prevention. As a transcription factor, p53 mainly exerts its function through transcription regulation of its target genes to initiate various cellular responses. To maintain its proper function, p53 is tightly regulated by a wide variety of regulators in cells. Thus, p53, its regulators and regulated genes form a complex p53 network which is composed of hundreds of genes and their products. microRNAs (miRNAs) are a class of endogenously expressed, small non-coding RNA molecules which play a key role in regulation of gene expression at the post-transcriptional level. Recent studies have demonstrated that miRNAs interact with p53 and its network at multiple levels. p53 regulates the transcription expression and the maturation of a group of miRNAs. On the other hand, miRNAs can regulate the activity and function of p53 through direct repression of p53 or its regulators in cells. These findings have demonstrated that miRNAs are important components in the p53 network, and also added another layer of complexity to the p53 network.

  5. Tumor Suppressor Function of CYLD in Nonmelanoma Skin Cancer

    Directory of Open Access Journals (Sweden)

    K. C. Masoumi

    2011-01-01

    Full Text Available Ubiquitin and ubiquitin-related proteins posttranslationally modify substrates, and thereby alter the functions of their targets. The ubiquitination process is involved in various physiological responses, and dysregulation of components of the ubiquitin system has been linked to many diseases including skin cancer. The ubiquitin pathways activated among skin cancers are highly diverse and may reflect the various characteristics of the cancer type. Basal cell carcinoma and squamous cell carcinoma, the most common types of human skin cancer, are instances where the involvement of the deubiquitination enzyme CYLD has been recently highlighted. In basal cell carcinoma, the tumor suppressor protein CYLD is repressed at the transcriptional levels through hedgehog signaling pathway. Downregulation of CYLD in basal cell carcinoma was also shown to interfere with TrkC expression and signaling, thereby promoting cancer progression. By contrast, the level of CYLD is unchanged in squamous cell carcinoma, instead, catalytic inactivation of CYLD in the skin has been linked to the development of squamous cell carcinoma. This paper will focus on the current knowledge that links CYLD to nonmelanoma skin cancers and will explore recent insights regarding CYLD regulation of NF-κB and hedgehog signaling during the development and progression of these types of human tumors.

  6. Epigenetic regulation of putative tumor suppressor TGFBI in human leukemias

    Institute of Scientific and Technical Information of China (English)

    Fang Hongbo; Liu Jing; Guo Dan; Liu Peixiang; Zhao Yongliang

    2014-01-01

    Background Both in vitro and in vivo data have demonstrated the TGFBI gene functions as a putative tumor suppressor and is frequently downregulated in human tumors of different histological types.The hypermethylation of the TGFBI promoter,as one of the main regulatory mechanisms,is associated with TGFBI silencing.In this study,we used a methylation-specific PCR (MSP) method to evaluate the methylation status of the TGFBI promoter in human leukemias.Methods Real-time RT-PCR and methylation-specific PCR approaches were performed to define the TGFBI expression and promoter methylation in human leukemia call lines and clinical samples.Genomic DNA was isolated from peripheral blood mononuclear cells from leukemia patients,bisulfite-converted,and analyzed by the MSP method.Results Hypermethylation of the TGFBI promoter occurred in leukemia cell lines and demethylation treatment reexpressed TGFBI at a substantially increased level in most of leukemia cell lines tested.Furthermore,a much higher level of CpG island methylation and a significantly lower TGFBI expression were also identified in clinical leukemia samples.Conclusion The results suggest an important role of promoter methylation in regulating TGFBI expression in leukemia,which provides a useful diagnostic marker for clinical management of human leukemias.

  7. Tropomyosin-1, A Putative Tumor-Suppressor and a Biomarker of Human Breast Cancer

    Science.gov (United States)

    2004-10-01

    cDNA. Lobular carcinoma - 2 A polyclonal pan-TM antibody that recognizes multiple TM Phyllodes tumor - 1 Not determined from the initial pathology...AD Award Number: DAMD17-98-1-8162 TITLE: Tropomyosin-1, A Putative Tumor -Suppressor and a Biomarker of Human Breast Cancer PRINCIPAL INVESTIGATOR...4. TITLE AND SUBTITLE 5. FUNDING NUMBERS Tropomyosin-l, A Putative Tumor -Suppressor and a Biomarker DAMD17-98-1-8162 of Human Breast Cancer 6. A UTHOR

  8. Expression of the p16{sup INK4a} tumor suppressor gene in rodent lung tumors

    Energy Technology Data Exchange (ETDEWEB)

    Swafford, D.S.; Tesfaigzi, J.; Belinsky, S.A.

    1995-12-01

    Aberrations on the short arm of chromosome 9 are among the earliest genetic changes in human cancer. p16{sup INK4a} is a candidate tumor suppressor gene that lies within human 9p21, a chromosome region associated with frequent loss of heterozygosity in human lung tumors. The p16{sup INK4a} protein functions as an inhibitor of cyclin D{sub 1}-dependent kinases that phosphorylate the retinoblastoma (Rb) tumor suppressor gene product enabling cell-cycle progression. Thus, overexpression of cyclin D{sub 1}, mutation of cyclin-dependent kinase genes, or loss of p16{sup INK4a} function, can all result in functional inactivation of Rb. Inactivation of Rb by mutation or deletion can result in an increase in p16{sup INK4a} transcription, suggesting that an increased p16{sup INK4a} expression in a tumor cell signals dysfunction of the pathway. The p16{sup (INK4a)} gene, unlike some tumor suppressor genes, is rarely inactivated by mutation. Instead, the expression of this gene is suppressed in some human cancers by hypermethylation of the CpG island within the first exon or by homozygous deletion: 686. Chromosome losses have been observed at 9p21 syntenic loci in tumors of the mouse and rat, two species often used as animal models for pulmonary carcinogenesis. Expression of p16{sup INK4a} is lost in some mouse tumor cell lines, often due to homozygous deletion. These observations indicate that p16{sup INK4a} dysfunction may play a role in the development of neoplasia in rodents as well as humans. The purpose of the current investigation was to define the extent to which p16{sup INK4a} dysfunction contributes to the development of rodent lung tumors and to determine the mechanism of inactivation of the gene. There is no evidence to suggest a loss of function of the p16{sup INK4a} tumor suppressor gene in these primary murine lung tumors by mutation, deletion, or methylation.

  9. Diaryl Disulfides as Novel Stabilizers of Tumor Suppressor Pdcd4

    Science.gov (United States)

    Schmid, Tobias; Blees, Johanna S.; Bajer, Magdalena M.; Wild, Janine; Pescatori, Luca; Cuzzucoli Crucitti, Giuliana; Scipione, Luigi; Costi, Roberta; Henrich, Curtis J.; Brüne, Bernhard; Colburn, Nancy H.; Di Santo, Roberto

    2016-01-01

    The translation inhibitor and tumor suppressor Pdcd4 was reported to be lost in various tumors and put forward as prognostic marker in tumorigenesis. Decreased Pdcd4 protein stability due to PI3K-mTOR-p70S6K1 dependent phosphorylation of Pdcd4 followed by β-TrCP1-mediated ubiquitination, and proteasomal destruction of the protein was characterized as a major mechanism contributing to the loss of Pdcd4 expression in tumors. In an attempt to identify stabilizers of Pdcd4, we used a luciferase-based high-throughput compatible cellular assay to monitor phosphorylation-dependent proteasomal degradation of Pdcd4 in response to mitogen stimulation. Following a screen of approximately 2000 compounds, we identified 1,2-bis(4-chlorophenyl)disulfide as a novel Pdcd4 stabilizer. To determine an initial structure-activity relationship, we used 3 additional compounds, synthesized according to previous reports, and 2 commercially available compounds for further testing, in which either the linker between the aryls was modified (compounds 2–4) or the chlorine residues were replaced by groups with different electronic properties (compounds 5 and 6). We observed that those compounds with alterations in the sulfide linker completely lost the Pdcd4 stabilizing potential. In contrast, modifications in the chlorine residues showed only minor effects on the Pdcd4 stabilizing activity. A reporter with a mutated phospho-degron verified the specificity of the compounds for stabilizing the Pdcd4 reporter. Interestingly, the active diaryl disulfides inhibited proliferation and viability at concentrations where they stabilized Pdcd4, suggesting that Pdcd4 stabilization might contribute to the anti-proliferative properties. Finally, computational modelling indicated that the flexibility of the disulfide linker might be necessary to exert the biological functions of the compounds, as the inactive compound appeared to be energetically more restricted. PMID:26982744

  10. Diaryl Disulfides as Novel Stabilizers of Tumor Suppressor Pdcd4.

    Science.gov (United States)

    Schmid, Tobias; Blees, Johanna S; Bajer, Magdalena M; Wild, Janine; Pescatori, Luca; Cuzzucoli Crucitti, Giuliana; Scipione, Luigi; Costi, Roberta; Henrich, Curtis J; Brüne, Bernhard; Colburn, Nancy H; Di Santo, Roberto

    2016-01-01

    The translation inhibitor and tumor suppressor Pdcd4 was reported to be lost in various tumors and put forward as prognostic marker in tumorigenesis. Decreased Pdcd4 protein stability due to PI3K-mTOR-p70S6K1 dependent phosphorylation of Pdcd4 followed by β-TrCP1-mediated ubiquitination, and proteasomal destruction of the protein was characterized as a major mechanism contributing to the loss of Pdcd4 expression in tumors. In an attempt to identify stabilizers of Pdcd4, we used a luciferase-based high-throughput compatible cellular assay to monitor phosphorylation-dependent proteasomal degradation of Pdcd4 in response to mitogen stimulation. Following a screen of approximately 2000 compounds, we identified 1,2-bis(4-chlorophenyl)disulfide as a novel Pdcd4 stabilizer. To determine an initial structure-activity relationship, we used 3 additional compounds, synthesized according to previous reports, and 2 commercially available compounds for further testing, in which either the linker between the aryls was modified (compounds 2-4) or the chlorine residues were replaced by groups with different electronic properties (compounds 5 and 6). We observed that those compounds with alterations in the sulfide linker completely lost the Pdcd4 stabilizing potential. In contrast, modifications in the chlorine residues showed only minor effects on the Pdcd4 stabilizing activity. A reporter with a mutated phospho-degron verified the specificity of the compounds for stabilizing the Pdcd4 reporter. Interestingly, the active diaryl disulfides inhibited proliferation and viability at concentrations where they stabilized Pdcd4, suggesting that Pdcd4 stabilization might contribute to the anti-proliferative properties. Finally, computational modelling indicated that the flexibility of the disulfide linker might be necessary to exert the biological functions of the compounds, as the inactive compound appeared to be energetically more restricted.

  11. Diaryl Disulfides as Novel Stabilizers of Tumor Suppressor Pdcd4.

    Directory of Open Access Journals (Sweden)

    Tobias Schmid

    Full Text Available The translation inhibitor and tumor suppressor Pdcd4 was reported to be lost in various tumors and put forward as prognostic marker in tumorigenesis. Decreased Pdcd4 protein stability due to PI3K-mTOR-p70S6K1 dependent phosphorylation of Pdcd4 followed by β-TrCP1-mediated ubiquitination, and proteasomal destruction of the protein was characterized as a major mechanism contributing to the loss of Pdcd4 expression in tumors. In an attempt to identify stabilizers of Pdcd4, we used a luciferase-based high-throughput compatible cellular assay to monitor phosphorylation-dependent proteasomal degradation of Pdcd4 in response to mitogen stimulation. Following a screen of approximately 2000 compounds, we identified 1,2-bis(4-chlorophenyldisulfide as a novel Pdcd4 stabilizer. To determine an initial structure-activity relationship, we used 3 additional compounds, synthesized according to previous reports, and 2 commercially available compounds for further testing, in which either the linker between the aryls was modified (compounds 2-4 or the chlorine residues were replaced by groups with different electronic properties (compounds 5 and 6. We observed that those compounds with alterations in the sulfide linker completely lost the Pdcd4 stabilizing potential. In contrast, modifications in the chlorine residues showed only minor effects on the Pdcd4 stabilizing activity. A reporter with a mutated phospho-degron verified the specificity of the compounds for stabilizing the Pdcd4 reporter. Interestingly, the active diaryl disulfides inhibited proliferation and viability at concentrations where they stabilized Pdcd4, suggesting that Pdcd4 stabilization might contribute to the anti-proliferative properties. Finally, computational modelling indicated that the flexibility of the disulfide linker might be necessary to exert the biological functions of the compounds, as the inactive compound appeared to be energetically more restricted.

  12. PML tumor suppressor protein is required for HCV production

    Energy Technology Data Exchange (ETDEWEB)

    Kuroki, Misao [Department of Tumor Virology, Okayama University Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, 2-5-1, Shikata-cho, Okayama 700-8558 (Japan); Research Fellow of the Japan Society for the Promotion of Science (Japan); Center for AIDS Research, Kumamoto University, Kumamoto 860-0811 (Japan); Ariumi, Yasuo, E-mail: ariumi@kumamoto-u.ac.jp [Department of Tumor Virology, Okayama University Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, 2-5-1, Shikata-cho, Okayama 700-8558 (Japan); Center for AIDS Research, Kumamoto University, Kumamoto 860-0811 (Japan); Hijikata, Makoto [Department of Viral Oncology, Institute for Virus Research, Kyoto University, Kyoto 606-8507 (Japan); Ikeda, Masanori; Dansako, Hiromichi [Department of Tumor Virology, Okayama University Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, 2-5-1, Shikata-cho, Okayama 700-8558 (Japan); Wakita, Takaji [Department of Virology II, National Institute of Infectious Diseases, Tokyo 162-8640 (Japan); Shimotohno, Kunitada [Research Center for Hepatitis and Immunology, National Center for Global Health and Medicine, Ichikawa, Chiba 272-8516 (Japan); Kato, Nobuyuki [Department of Tumor Virology, Okayama University Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, 2-5-1, Shikata-cho, Okayama 700-8558 (Japan)

    2013-01-11

    Highlights: Black-Right-Pointing-Pointer PML tumor suppressor protein is required for HCV production. Black-Right-Pointing-Pointer PML is dispensable for HCV RNA replication. Black-Right-Pointing-Pointer HCV could not alter formation of PML-NBs. Black-Right-Pointing-Pointer INI1 and DDX5, PML-related proteins, are involved in HCV life cycle. -- Abstract: PML tumor suppressor protein, which forms discrete nuclear structures termed PML-nuclear bodies, has been associated with several cellular functions, including cell proliferation, apoptosis and antiviral defense. Recently, it was reported that the HCV core protein colocalizes with PML in PML-NBs and abrogates the PML function through interaction with PML. However, role(s) of PML in HCV life cycle is unknown. To test whether or not PML affects HCV life cycle, we examined the level of secreted HCV core and the infectivity of HCV in the culture supernatants as well as the level of HCV RNA in HuH-7-derived RSc cells, in which HCV-JFH1 can infect and efficiently replicate, stably expressing short hairpin RNA targeted to PML. In this context, the level of secreted HCV core and the infectivity in the supernatants from PML knockdown cells was remarkably reduced, whereas the level of HCV RNA in the PML knockdown cells was not significantly affected in spite of very effective knockdown of PML. In fact, we showed that PML is unrelated to HCV RNA replication using the subgenomic HCV-JFH1 replicon RNA, JRN/3-5B. Furthermore, the infectivity of HCV-like particle in the culture supernatants was significantly reduced in PML knockdown JRN/3-5B cells expressing core to NS2 coding region of HCV-JFH1 genome using the trans-packaging system. Finally, we also demonstrated that INI1 and DDX5, the PML-related proteins, are involved in HCV production. Taken together, these findings suggest that PML is required for HCV production.

  13. A Systems Approach Identifies Essential FOXO3 Functions at Key Steps of Terminal Erythropoiesis.

    Directory of Open Access Journals (Sweden)

    Raymond Liang

    2015-10-01

    Full Text Available Circulating red blood cells (RBCs are essential for tissue oxygenation and homeostasis. Defective terminal erythropoiesis contributes to decreased generation of RBCs in many disorders. Specifically, ineffective nuclear expulsion (enucleation during terminal maturation is an obstacle to therapeutic RBC production in vitro. To obtain mechanistic insights into terminal erythropoiesis we focused on FOXO3, a transcription factor implicated in erythroid disorders. Using an integrated computational and experimental systems biology approach, we show that FOXO3 is essential for the correct temporal gene expression during terminal erythropoiesis. We demonstrate that the FOXO3-dependent genetic network has critical physiological functions at key steps of terminal erythropoiesis including enucleation and mitochondrial clearance processes. FOXO3 loss deregulated transcription of genes implicated in cell polarity, nucleosome assembly and DNA packaging-related processes and compromised erythroid enucleation. Using high-resolution confocal microscopy and imaging flow cytometry we show that cell polarization is impaired leading to multilobulated Foxo3-/- erythroblasts defective in nuclear expulsion. Ectopic FOXO3 expression rescued Foxo3-/- erythroblast enucleation-related gene transcription, enucleation defects and terminal maturation. Remarkably, FOXO3 ectopic expression increased wild type erythroblast maturation and enucleation suggesting that enhancing FOXO3 activity may improve RBCs production. Altogether these studies uncover FOXO3 as a novel regulator of erythroblast enucleation and terminal maturation suggesting FOXO3 modulation might be therapeutic in disorders with defective erythroid maturation.

  14. RASSF6; the Putative Tumor Suppressor of the RASSF Family

    Directory of Open Access Journals (Sweden)

    Hiroaki Iwasa

    2015-12-01

    Full Text Available Humans have 10 genes that belong to the Ras association (RA domain family (RASSF. Among them, RASSF7 to RASSF10 have the RA domain in the N-terminal region and are called the N-RASSF proteins. In contradistinction to them, RASSF1 to RASSF6 are referred to as the C-RASSF proteins. The C-RASSF proteins have the RA domain in the middle region and the Salvador/RASSF/Hippo domain in the C-terminal region. RASSF6 additionally harbors the PSD-95/Discs large/ZO-1 (PDZ-binding motif. Expression of RASSF6 is epigenetically suppressed in human cancers and is generally regarded as a tumor suppressor. RASSF6 induces caspase-dependent and -independent apoptosis. RASSF6 interacts with mammalian Ste20-like kinases (homologs of Drosophila Hippo and cross-talks with the Hippo pathway. RASSF6 binds MDM2 and regulates p53 expression. The interactions with Ras and Modulator of apoptosis 1 (MOAP1 are also suggested by heterologous protein-protein interaction experiments. RASSF6 regulates apoptosis and cell cycle through these protein-protein interactions, and is implicated in the NF-κB and JNK signaling pathways. We summarize our current knowledge about RASSF6 and discuss what common and different properties RASSF6 and the other C-RASSF proteins have.

  15. ERF is a Potential ERK Modulated Tumor Suppressor in Prostate Cancer

    Science.gov (United States)

    2016-10-01

    AWARD NUMBER: W81XWH-15-1-0277 TITLE: ERF is a Potential ERK-Modulated Tumor Suppressor in Prostate Cancer PRINCIPAL INVESTIGATOR: Dr. Rohit...Bose CONTRACTING ORGANIZATION: Sloan Kettering Institute for Cancer Research New York, NY 10065 REPORT DATE: October 2016 TYPE OF REPORT...4. TITLE AND SUBTITLE ERF is a Potential ERK-Modulated Tumor Suppressor in Prostate Cancer 5a. CONTRACT NUMBER 5b. GRANT NUMBER W81XWH-15-1-0277

  16. The Role of Tumor Metastases Suppressor Gene, Drg-1, in Breast Cancer

    Science.gov (United States)

    2008-03-01

    catenin. Nuclear staining beta-catenin 36 72 Breast Carcinoma Phyllodes tumor 73 74 75 Reduced...AD_________________ Award Number: W81XWH-05-1-0309 TITLE: The Role of Tumor Metastases Suppressor...TYPE Annual 3. DATES COVERED (From - To) 1 MAR 2007 - 29 FEB 2008 4. TITLE AND SUBTITLE 5a. CONTRACT NUMBER The Role of Tumor Metastases

  17. Tumor Suppressor Inactivation in the Pathogenesis of Adult T-Cell Leukemia

    Directory of Open Access Journals (Sweden)

    Christophe Nicot

    2015-01-01

    Full Text Available Tumor suppressor functions are essential to control cellular proliferation, to activate the apoptosis or senescence pathway to eliminate unwanted cells, to link DNA damage signals to cell cycle arrest checkpoints, to activate appropriate DNA repair pathways, and to prevent the loss of adhesion to inhibit initiation of metastases. Therefore, tumor suppressor genes are indispensable to maintaining genetic and genomic integrity. Consequently, inactivation of tumor suppressors by somatic mutations or epigenetic mechanisms is frequently associated with tumor initiation and development. In contrast, reactivation of tumor suppressor functions can effectively reverse the transformed phenotype and lead to cell cycle arrest or death of cancerous cells and be used as a therapeutic strategy. Adult T-cell leukemia/lymphoma (ATLL is an aggressive lymphoproliferative disease associated with infection of CD4 T cells by the Human T-cell Leukemia Virus Type 1 (HTLV-I. HTLV-I-associated T-cell transformation is the result of a multistep oncogenic process in which the virus initially induces chronic T-cell proliferation and alters cellular pathways resulting in the accumulation of genetic defects and the deregulated growth of virally infected cells. This review will focus on the current knowledge of the genetic and epigenetic mechanisms regulating the inactivation of tumor suppressors in the pathogenesis of HTLV-I.

  18. Constitutively nuclear FOXO3a localization predicts poor survival and promotes Akt phosphorylation in breast cancer.

    Directory of Open Access Journals (Sweden)

    Jie Chen

    Full Text Available BACKGROUND: The PI3K-Akt signal pathway plays a key role in tumorigenesis and the development of drug-resistance. Cytotoxic chemotherapy resistance is linked to limited therapeutic options and poor prognosis. METHODOLOGY/PRINCIPAL FINDINGS: Examination of FOXO3a and phosphorylated-Akt (P-Akt expression in breast cancer tissue microarrays showed nuclear FOXO3a was associated with lymph node positivity (p = 0.052, poor prognosis (p = 0.014, and P-Akt expression in invasive ductal carcinoma. Using tamoxifen and doxorubicin-sensitive and -resistant breast cancer cell lines as models, we found that doxorubicin- but not tamoxifen-resistance is associated with nuclear accumulation of FOXO3a, consistent with the finding that sustained nuclear FOXO3a is associated with poor prognosis. We also established that doxorubicin treatment induces proliferation arrest and FOXO3a nuclear relocation in sensitive breast cancer cells. Induction of FOXO3a activity in doxorubicin-sensitive MCF-7 cells was sufficient to promote Akt phosphorylation and arrest cell proliferation. Conversely, knockdown of endogenous FOXO3a expression reduced PI3K/Akt activity. Using MDA-MB-231 cells, in which FOXO3a activity can be induced by 4-hydroxytamoxifen, we showed that FOXO3a induction up-regulates PI3K-Akt activity and enhanced doxorubicin resistance. However FOXO3a induction has little effect on cell proliferation, indicating that FOXO3a or its downstream activity is deregulated in the cytotoxic drug resistant breast cancer cells. Thus, our results suggest that sustained FOXO3a activation can enhance hyperactivation of the PI3K/Akt pathway. CONCLUSIONS/SIGNIFICANCE: Together these data suggest that lymph node metastasis and poor survival in invasive ductal breast carcinoma are linked to an uncoupling of the Akt-FOXO3a signaling axis. In these breast cancers activated Akt fails to inactivate and re-localize FOXO3a to the cytoplasm, and nuclear-targeted FOXO3a does not induce cell

  19. The role of tumor suppressor p53 in the antioxidant defense and metabolism

    OpenAIRE

    2014-01-01

    Tumor suppressor p53 is inactivated in most cancers and the critical role of p53 in the suppression of carcinogenesis has been confirmed in many mouse models. The protein product of the tumor suppressor p53 gene works as a transcriptional regulator, activating expression of numerous genes involved in cell death, cell cycle arrest, senescence, DNA-repair and many other processes. In spite of the multiple efforts to characterize the functions of p53, the mechanisms of tumor suppression by p53 a...

  20. Cell proliferation is a key determinant of the outcome of FOXO3a activation

    Energy Technology Data Exchange (ETDEWEB)

    Poulsen, Raewyn C., E-mail: raewyn.poulsen@gmail.com; Carr, Andrew J.; Hulley, Philippa A.

    2015-06-19

    The FOXO family of forkhead transcription factors have a pivotal role in determining cell fate in response to oxidative stress. FOXO activity can either promote cell survival or induce cell death. Increased FOXO-mediated cell death has been implicated in the pathogenesis of degenerative diseases affecting musculoskeletal tissues. The aim of this study was to determine the conditions under which one member of the FOXO family, FOXO3a, promotes cell survival as opposed to cell death. Treatment of primary human tenocytes with 1 pM hydrogen peroxide for 18 h resulted in increased protein levels of FOXO3a. In peroxide-treated cells cultured in low serum media, FOXO3a inhibited cell proliferation and protected against apoptosis. However in peroxide treated cells cultured in high serum media, cell proliferation was unchanged but level of apoptosis significantly increased. Similarly, in tenocytes transduced to over-express FOXO3a, cell proliferation was inhibited and level of apoptosis unchanged in cells cultured in low serum. However there was a robust increase in cell death in FOXO3a-expressing cells cultured in high serum. Inhibition of cell proliferation in either peroxide-treated or FOXO3a-expressing cells cultured in high serum protected against apoptosis induction. Conversely, addition of a Chk2 inhibitor to peroxide-treated or FOXO3a-expressing cells overrode the inhibitory effect of FOXO3a on cell proliferation and led to increased apoptosis in cells cultured in low serum. This study demonstrates that proliferating cells may be particularly susceptible to the apoptosis-inducing actions of FOXO3a. Inhibition of cell proliferation by FOXO3a may be a critical event in allowing the pro-survival rather than the pro-apoptotic activity of FOXO3a to prevail. - Highlights: • FOXO3a activity can result in either promotion of cell survival or apoptosis. • The outcome of FOXO3a activation differs in proliferating compared to non-proliferating cells. • Proliferating

  1. Alternative poladenylation of tumor suppressor genes in small intestinal neuroendocrine tumors

    Directory of Open Access Journals (Sweden)

    Anders eRehfeld

    2014-04-01

    Full Text Available The tumorigenesis of small intestinal neuroendocrine tumors is poorly understood. Recent studies have associated alternative polyadenylation with proliferation, cell transformation and cancer. Polyadenylation is the process in which the pre-mRNA is cleaved at a polyA site and a polyA tail is added. Genes with two or more polyA sites can undergo alternative polyadenylation. This produces two or more distinct mRNA isoforms with different 3’ untranslated regions. Additionally, alternative polyadenylation can also produce mRNAs containing different 3’-terminal coding regions. Therefore, alternative polyadenylation alters both the repertoire and the expression level of proteins.Here we used high-throughput sequencing data to map polyA sites and characterize polyadenylation genome-wide in three small intestinal neuroendocrine tumors and a reference sample. In the tumors sixteen genes showed significant changes of alternative polyadenylation pattern, which lead to either the 3’ truncation of mRNA coding regions or 3’ untranslated regions. Among these, 11 genes had been previously associated with cancer, with 4 genes being known tumor suppressors: DCC, PDZD2, MAGI1 and DACT2. We validated the alternative polyadenylation in 3 out of 3 cases with Q-RT-PCR. Our findings suggest that changes of alternative polyadenylation pattern in these 16 genes could be involved in the tumorigenesis of small intestinal neuroendocrine tumors. Furthermore, they also point to alternative polyadenylation as a new target for both diagnostic and treatment of small intestinal neuroendocrine tumors. The identified genes with alternative polyadenylation specific to the small intestinal neuroendocrine tumors could be further tested as diagnostic markers and drug targets for disease prevention and treatment.

  2. Molecular cloning, characterisation and functional analysis of the duck Forkhead box O3 (FOXO3) gene.

    Science.gov (United States)

    Gan, W; He, H; Li, L

    2016-04-01

    1. The Forkhead box O3 (FOXO3) transcription factor is a crucial regulator of cell fate that controls proliferation, apoptosis and differentiation. However, the role of FOXO3 regulation in duck myoblasts is not fully understood. 2. The aim of this study was to clone and determine the complete coding sequence (CDS) of the duck FOXO3 gene and to assess its function in myoblasts. 3. Primers specific for the predicted duck FOXO3 gene were designed using the public mallard duck reference sequence in GenBank. The CDS was cloned by RT-PCR and double digested to generate the expression vector pEGFP-N1-FOXO3. 4. Sequence analysis showed that the full-length FOXO3 CDS is 1467 bp, encoding 488 amino acids and is highly conserved across many bird species. Amino acid sequence analysis revealed a DNA-binding domain (aa 1-77). 5. Myoblast transfection with pEGFP-N1-FOXO3 showed that FOXO3 mRNA expression at 24 h was elevated in pEGFP-N1-FOXO3-transfected myoblasts compared to pEGFP-N1-transfected cells or controls. MRF4, MyoD, MyoG, Myf5 and PAX7 mRNA expression in the pEGFP-N1-FOXO3 group was lowest. However, myostatin (MSTN) and PAX3 mRNA expression did not differ. 6. These results suggest that FOXO3 plays a critical role in the proliferation and differentiation of duck myoblasts.

  3. Immunomodulatory Function of the Tumor Suppressor p53 in Host Immune Response and the Tumor Microenvironment.

    Science.gov (United States)

    Cui, Yan; Guo, Gang

    2016-11-19

    The tumor suppressor p53 is the most frequently mutated gene in human cancers. Most of the mutations are missense leading to loss of p53 function in inducing apoptosis and senescence. In addition to these autonomous effects of p53 inactivation/dysfunction on tumorigenesis, compelling evidence suggests that p53 mutation/inactivation also leads to gain-of-function or activation of non-autonomous pathways, which either directly or indirectly promote tumorigenesis. Experimental and clinical results suggest that p53 dysfunction fuels pro-tumor inflammation and serves as an immunological gain-of-function driver of tumorigenesis via skewing immune landscape of the tumor microenvironment (TME). It is now increasingly appreciated that p53 dysfunction in various cellular compartments of the TME leads to immunosuppression and immune evasion. Although our understanding of the cellular and molecular processes that link p53 activity to host immune regulation is still incomplete, it is clear that activating/reactivating the p53 pathway in the TME also represents a compelling immunological strategy to reverse immunosuppression and enhance antitumor immunity. Here, we review our current understanding of the potential cellular and molecular mechanisms by which p53 participates in immune regulation and discuss how targeting the p53 pathway can be exploited to alter the immunological landscape of tumors for maximizing therapeutic outcome.

  4. Frequent alteration of the tumor suppressor gene APC in sporadic canine colorectal tumors.

    Science.gov (United States)

    Youmans, Lydia; Taylor, Cynthia; Shin, Edwin; Harrell, Adrienne; Ellis, Angela E; Séguin, Bernard; Ji, Xinglai; Zhao, Shaying

    2012-01-01

    Sporadic canine colorectal cancers (CRCs) should make excellent models for studying the corresponding human cancers. To molecularly characterize canine CRC, we investigated exonic sequence mutations of adenomatous polyposis coli (APC), the best known tumor suppressor gene of human CRC, in 23 sporadic canine colorectal tumors, including 8 adenomas and 15 adenocarcinomas, via exon-resequencing analysis. As a comparison, we also performed the same sequencing analysis on 10 other genes, either located at human 5q22 (the same locus as APC) or 18q21 (also frequently altered in human CRC), or known to play a role in human carcinogenesis. We noted that APC was the most significantly mutated gene in both canine adenomas and adenocarcinomas among the 11 genes examined. Significantly, we detected large deletions of ≥ 10 bases, many clustered near the mutation cluster region, as well as single or two base deletions in ~70% canine tumors of both subtypes. These observations indicate that like in the human, APC is also frequently altered in sporadic colorectal tumors in the dog and its alteration is an early event in canine colorectal tumorigenesis. Our study provides further evidence demonstrating the molecular similarity in pathogenesis between sporadic human and canine CRCs. This work, along with our previous copy number abnormality study, supports that sporadic canine CRCs are valid models of human CRCs at the molecular level.

  5. Immunomodulatory Function of the Tumor Suppressor p53 in Host Immune Response and the Tumor Microenvironment

    Directory of Open Access Journals (Sweden)

    Yan Cui

    2016-11-01

    Full Text Available The tumor suppressor p53 is the most frequently mutated gene in human cancers. Most of the mutations are missense leading to loss of p53 function in inducing apoptosis and senescence. In addition to these autonomous effects of p53 inactivation/dysfunction on tumorigenesis, compelling evidence suggests that p53 mutation/inactivation also leads to gain-of-function or activation of non-autonomous pathways, which either directly or indirectly promote tumorigenesis. Experimental and clinical results suggest that p53 dysfunction fuels pro-tumor inflammation and serves as an immunological gain-of-function driver of tumorigenesis via skewing immune landscape of the tumor microenvironment (TME. It is now increasingly appreciated that p53 dysfunction in various cellular compartments of the TME leads to immunosuppression and immune evasion. Although our understanding of the cellular and molecular processes that link p53 activity to host immune regulation is still incomplete, it is clear that activating/reactivating the p53 pathway in the TME also represents a compelling immunological strategy to reverse immunosuppression and enhance antitumor immunity. Here, we review our current understanding of the potential cellular and molecular mechanisms by which p53 participates in immune regulation and discuss how targeting the p53 pathway can be exploited to alter the immunological landscape of tumors for maximizing therapeutic outcome.

  6. Immunomodulatory Function of the Tumor Suppressor p53 in Host Immune Response and the Tumor Microenvironment

    Science.gov (United States)

    Cui, Yan; Guo, Gang

    2016-01-01

    The tumor suppressor p53 is the most frequently mutated gene in human cancers. Most of the mutations are missense leading to loss of p53 function in inducing apoptosis and senescence. In addition to these autonomous effects of p53 inactivation/dysfunction on tumorigenesis, compelling evidence suggests that p53 mutation/inactivation also leads to gain-of-function or activation of non-autonomous pathways, which either directly or indirectly promote tumorigenesis. Experimental and clinical results suggest that p53 dysfunction fuels pro-tumor inflammation and serves as an immunological gain-of-function driver of tumorigenesis via skewing immune landscape of the tumor microenvironment (TME). It is now increasingly appreciated that p53 dysfunction in various cellular compartments of the TME leads to immunosuppression and immune evasion. Although our understanding of the cellular and molecular processes that link p53 activity to host immune regulation is still incomplete, it is clear that activating/reactivating the p53 pathway in the TME also represents a compelling immunological strategy to reverse immunosuppression and enhance antitumor immunity. Here, we review our current understanding of the potential cellular and molecular mechanisms by which p53 participates in immune regulation and discuss how targeting the p53 pathway can be exploited to alter the immunological landscape of tumors for maximizing therapeutic outcome. PMID:27869779

  7. Correlation of primary tumor size and axillary nodal status with tumor suppressor gene p53 in breast carcinoma

    Directory of Open Access Journals (Sweden)

    Topić Brano

    2002-01-01

    Full Text Available Correlation of standard path morphological prognostic parameters, primary tumor size and axillary nodal status with new prognostic factor in breast carcinoma: tumor suppressor gene p53 was analyzed. The studied sample included 65 women who underwent surgery for breast carcinoma at the Surgical Clinic of Clinical Center Banja Luka, from January 1st 1997 till January 1st 1999. Statistical data analysis was performed and correlation of prognostic factors was determined. The majority of authors in this field agree that the primary tumor size and axillary nodal status are the two most important prognostic factors. These factors are the best predictors of prognosis and survival of women who had the tumor and were operated on. Tumor markers were immunohistochemically determined in the last ten years and, according to the majority of authors, are still considered the additional or relative prognostic factors in breast carcinoma. Their prognostic value and significance increase almost daily. Most frequently determined tumor markers are bcl-2, pS2, Ki-67 and p53. There was a positive, directly proportional relationship between primary tumor size and tumor suppressor gene p53, but there was no positive correlation between the axillary nodal status and tumor suppressor gene p53. Significance of determination of new tumor markers as the prognostic factors was emphasized. These markers represent a powerful tool in the early detection and prevention of breast carcinoma.

  8. BRCA1 and p53 tumor suppressor molecules in Alzheimer's disease.

    Science.gov (United States)

    Nakanishi, Atsuko; Minami, Akari; Kitagishi, Yasuko; Ogura, Yasunori; Matsuda, Satoru

    2015-01-28

    Tumor suppressor molecules play a pivotal role in regulating DNA repair, cell proliferation, and cell death, which are also important processes in the pathogenesis of Alzheimer's disease. Alzheimer's disease is the most common neurodegenerative disorder, however, the precise molecular events that control the death of neuronal cells are unclear. Recently, a fundamental role for tumor suppressor molecules in regulating neurons in Alzheimer's disease was highlighted. Generally, onset of neurodegenerative diseases including Alzheimer's disease may be delayed with use of dietary neuro-protective agents against oxidative stresses. Studies suggest that dietary antioxidants are also beneficial for brain health in reducing disease-risk and in slowing down disease-progression. We summarize research advances in dietary regulation for the treatment of Alzheimer's disease with a focus on its modulatory roles in BRCA1 and p53 tumor suppressor expression, in support of further therapeutic research in this field.

  9. The potential for tumor suppressor gene therapy in head and neck cancer.

    Science.gov (United States)

    Birkeland, Andrew C; Ludwig, Megan L; Spector, Matthew E; Brenner, J Chad

    2016-01-01

    Head and neck squamous cell carcinoma remains a highly morbid and fatal disease. Importantly, genomic sequencing of head and neck cancers has identified frequent mutations in tumor suppressor genes. While targeted therapeutics increasingly are being investigated in head and neck cancer, the majority of these agents are against overactive/overexpressed oncogenes. Therapy to restore lost tumor suppressor gene function remains a key and under-addressed niche in trials for head and neck cancer. Recent advances in gene editing have captured the interest of both the scientific community and the public. As our technology for gene editing and gene expression modulation improves, addressing lost tumor suppressor gene function in head and neck cancers is becoming a reality. This review will summarize new techniques, challenges to implementation, future directions, and ethical ramifications of gene therapy in head and neck cancer.

  10. The association of FOXO3A gene polymorphisms with serum FOXO3A levels and oxidative stress markers in vitiligo patients.

    Science.gov (United States)

    Ozel Turkcu, Ummuhani; Solak Tekin, Nilgun; Gokdogan Edgunlu, Tuba; Karakas Celik, Sevim; Oner, Setenay

    2014-02-15

    Vitiligo is an acquired epidermal pigment loss of the skin. Oxidative stress is one of the major theories in the pathophysiology of vitiligo. FOXO3A is the forkhead members of the class O (FOXO) transcription factors, and plays an important role in cell cycle regulation, apoptosis, oxidative stress, and DNA repair. The aim of our study was to investigate FOXO3A gene polymorphisms and FOXO3A protein levels, activities of superoxide dismutase (SOD) and catalase antioxidant enzymes in vitiligo patients and healthy controls. Moreover, the level of plasma advanced oxidation protein products (AOPP) in subjects was evaluated to understand the possible role of protein oxidation in disease etiology. Study groups included 82 vitiligo patients and 81 unrelated healthy controls. FOXO3A polymorphisms were determined using polymerase chain reaction-restriction fragment length polymorphism method. FOXO3A levels and catalase activity were measured by ELISA whereas AOPP levels and SOD activity was measured by spectrophotometric analysis. We found a significant relationship between rs4946936 polymorphism of FOXO3A gene and vitiligo/active vitiligo patients (p=0.017; p=0.019 respectively), but not for rs2253310 (p>0.05). SOD activity and AOPP levels of vitiligo patient were increased compared with control group, whereas FOXO3A levels and catalase enzyme activity of vitiligo patient were decreased compared with control group (pvitiligo, especially active vitiligo. Moreover, our results confirm that oxidative stress may play a role in the pathophysiology of vitiligo. Further studies with larger samples are required to elucidate the role of FOXO3A in vitiligo.

  11. Tumor suppressor p53 and its gain-of-function mutants in cancer

    OpenAIRE

    2013-01-01

    Tumor suppressor p53 plays a pivotal role in tumor suppression. p53 is the most frequently mutated gene in cancer. As a transcription factor, p53 mainly exerts its role in tumor suppression through transcriptional regulation of its downstream target genes. Thus, p53 and its target genes form a complex p53 signaling pathway to regulate a wide variety of biological processes to prevent tumorigenesis. Recent studies have revealed that in addition to apoptosis, cell cycle arrest and senescence, p...

  12. Quantitative Methylation Profiles for Multiple Tumor Suppressor Gene Promoters in Salivary Gland Tumors

    Science.gov (United States)

    Durr, Megan L.; Mydlarz, Wojciech K.; Shao, Chunbo; Zahurak, Marianna L.; Chuang, Alice Y.; Hoque, Mohammad O.; Westra, William H.; Liegeois, Nanette J.; Califano, Joseph A.; Sidransky, David; Ha, Patrick K.

    2010-01-01

    Background Methylation profiling of tumor suppressor gene (TSGs) promoters is quickly becoming a powerful diagnostic tool for the early detection, prognosis, and even prediction of clinical response to treatment. Few studies address this in salivary gland tumors (SGTs); hence the promoter methylation profile of various TSGs was quantitatively assessed in primary SGT tissue to determine if tumor-specific alterations could be detected. Methodology DNA isolated from 78 tumor and 17 normal parotid gland specimens was assayed for promoter methylation status of 19 TSGs by fluorescence-based, quantitative methylation-specific PCR (qMSP). The data were utilized in a binary fashion as well as quantitatively (using a methylation quotient) allowing for better profiling and interpretation of results. Principal Findings The average number of methylation events across the studied genes was highest in salivary duct carcinoma (SDC), with a methylation value of 9.6, compared to the normal 4.5 (p<0.0003). There was a variable frequency and individual methylation quotient detected, depending on the TSG and the tumor type. When comparing normal, benign, and malignant SGTs, there was a statistically significant trend for increasing methylation in APC, Mint 1, PGP9.5, RAR-β, and Timp3. Conclusions/Significance Screening promoter methylation profiles in SGTs showed considerable heterogeneity. The methylation status of certain markers was surprisingly high in even normal salivary tissue, confirming the need for such controls. Several TSGs were found to be associated with malignant SGTs, especially SDC. Further study is needed to evaluate the potential use of these associations in the detection, prognosis, and therapeutic outcome of these rare tumors. PMID:20520817

  13. Acidic Fibroblast Growth Factor Promotes Endothelial Progenitor Cells Function via Akt/FOXO3a Pathway.

    Directory of Open Access Journals (Sweden)

    Liya Huang

    Full Text Available Acidic fibroblast growth factor (FGF1 has been suggested to enhance the functional activities of endothelial progenitor cells (EPCs. The Forkhead homeobox type O transcription factors (FOXOs, a key substrate of the survival kinase Akt, play important roles in regulation of various cellular processes. We previously have shown that FOXO3a is the main subtype of FOXOs expressed in EPCs. Here, we aim to determine whether FGF1 promotes EPC function through Akt/FOXO3a pathway. Human peripheral blood derived EPCs were transduced with adenoviral vectors either expressing a non-phosphorylable, constitutively active triple mutant of FOXO3a (Ad-TM-FOXO3a or a GFP control (Ad-GFP. FGF1 treatment improved functional activities of Ad-GFP transduced EPCs, including cell viability, proliferation, antiapoptosis, migration and tube formation, whereas these beneficial effects disappeared by Akt inhibitor pretreatment. Moreover, EPC function was declined by Ad-TM-FOXO3a transduction and failed to be attenuated even with FGF1 treatment. FGF1 upregulated phosphorylation levels of Akt and FOXO3a in Ad-GFP transduced EPCs, which were repressed by Akt inhibitor pretreatment. However, FGF1 failed to recover Ad-TM-FOXO3a transduced EPCs from dysfunction. These data indicate that FGF1 promoting EPC function is at least in part mediated through Akt/FOXO3a pathway. Our study may provide novel ideas for enhancing EPC angiogenic ability and optimizing EPC transplantation therapy in the future.

  14. Is Rab25 a tumor promoter or suppressor--context dependency on RCP status?

    Science.gov (United States)

    Tang, Bor Luen

    2010-08-01

    Conflicting reports in the literature suggest that Rab25 could either be a context dependent promoter or suppressor of tumorigenesis. We hypothesized that whether Rab25 acts as a promoter or suppressor in tumor progression depends on the expression status of its effector, the Rab coupling protein (RCP). An elevated expression of RCP resulting from genomic amplification may enhance Rab25's tumor progression activity. Elevation of Rab25 alone may sequester endogenous RCP, and attenuates its activating effect on other oncogenic products, such as mutant Ras.

  15. Multiplexed methylation profiles of tumor suppressor genes and clinical outcome in lung cancer

    Directory of Open Access Journals (Sweden)

    Venditti Julio

    2010-09-01

    Full Text Available Abstract Background Changes in DNA methylation of crucial cancer genes including tumor suppressors can occur early in carcinogenesis, being potentially important early indicators of cancer. The objective of this study was to examine a multiplexed approach to assess the methylation of tumor suppressor genes as tumor stratification and clinical outcome prognostic biomarkers for lung cancer. Methods A multicandidate probe panel interrogated DNA for aberrant methylation status in 18 tumor suppressor genes in lung cancer using a methylation-specific multiplex ligation-dependent probe amplification assay (MS-MLPA. Lung cancer cell lines (n = 7, and primary lung tumors (n = 54 were examined using MS-MLPA. Results Genes frequently methylated in lung cancer cell lines including SCGB3A1, ID4, CCND2 were found among the most commonly methylated in the lung tumors analyzed. HLTF, BNIP3, H2AFX, CACNA1G, TGIF, ID4 and CACNA1A were identified as novel tumor suppressor candidates methylated in lung tumors. The most frequently methylated genes in lung tumors were SCGB3A1 and DLC1 (both 50.0%. Methylation rates for ID4, DCL1, BNIP3, H2AFX, CACNA1G and TIMP3 were significantly different between squamous and adenocarcinomas. Methylation of RUNX3, SCGB3A1, SFRP4, and DLC1 was significantly associated with the extent of the disease when comparing localized versus metastatic tumors. Moreover, methylation of HTLF, SFRP5 and TIMP3 were significantly associated with overall survival. Conclusions MS-MLPA can be used for classification of certain types of lung tumors and clinical outcome prediction. This latter is clinically relevant by offering an adjunct strategy for the clinical management of lung cancer patients.

  16. FOXO3a Gene Polymorphism Associated with Asthma in Indian Population

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    Shravani Barkund

    2015-01-01

    Full Text Available Asthma is a chronic inflammatory disorder delineated by a heightened immunological response due to environmental or genetic factors. Single nucleotide polymorphism studies have shown that FOXO3a plays a pivotal role in maintaining immunoregulation. Polymorphism in FOXO3a has been linked to inflammatory diseases such as chronic obstructive pulmonary disease (COPD, Rheumatoid Arthritis, and Crohn’s disease suggesting that FOXO3a may be associated with asthma. Airway inflammation in asthma is characterized by activation of T helper type 2 (Th2 T cells and Foxo family members are reported to play critical roles in the suppression of T cell activation. Thus this study was undertaken to investigate an association between single nucleotide polymorphism of the FOXO3a (rs13217795, C>T transition gene and asthma in Indian population. To our knowledge we are the first ones reporting an association between FOXO3a and asthma.

  17. AZU-1: A Candidate Breast Tumor Suppressor and Biomarker for Tumor Progression

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Huei-Mei; Schmeichel, Karen L; Mian, I. Saira; Lelie`vre, Sophie; Petersen, Ole W; Bissell, Mina J

    2000-02-04

    To identify genes misregulated in the final stages of breast carcinogenesis, we performed differential display to compare the gene expression patterns of the human tumorigenic mammary epithelial cells, HMT-3522-T4-2, with those of their immediate premalignant progenitors, HMT-3522-S2. We identified a novel gene, called anti-zuai-1 (AZU-1), that was abundantly expressed in non- and premalignant cells and tissues but was appreciably reduced in breast tumor cell types and in primary tumors. The AZU-1 gene encodes an acidic 571-amino-acid protein containing at least two structurally distinct domains with potential protein-binding functions: an N-terminal serine and proline-rich domain with a predicted immunoglobulin-like fold and a C-terminal coiled-coil domain. In HMT-3522 cells, the bulk of AZU-1 protein resided in a detergent-extractable cytoplasmic pool and was present at much lower levels in tumorigenic T4-2 cells than in their nonmalignant counterparts. Reversion of the tumorigenic phenotype of T4-2 cells, by means described previously, was accompanied by the up-regulation of AZU-1. In addition, reexpression of AZU-1 in T4-2 cells, using viral vectors, was sufficient to reduce their malignant phenotype substantially, both in culture and in vivo. These results indicate that AZU-1 is a candidate breast tumor suppressor that may exert its effects by promoting correct tissue morphogenesis.

  18. Tumor suppressor ARF: The new player of innate immunity.

    Science.gov (United States)

    Través, Paqui G; Luque, Alfonso; Hortelano, Sonsoles

    2012-09-01

    ARF (alternative reading frame) is one of the most important tumor regulator playing critical roles in controlling tumor initiation and progression. Recently, we have demonstrated a novel and unexpected role for ARF as modulator of inflammatory responses.

  19. FoxO3 induces reversible cardiac atrophy and autophagy in a transgenic mouse model.

    Science.gov (United States)

    Schips, Tobias G; Wietelmann, Astrid; Höhn, Katharina; Schimanski, Silvia; Walther, Paul; Braun, Thomas; Wirth, Thomas; Maier, Harald J

    2011-09-01

    The transcription factor FoxO3 contributes to anti-hypertrophic signalling in the heart presumably by regulating autophagic-lysosomal and ubiquitin-proteasomal pathways. We wanted to study FoxO3 function in the adult heart in vivo by expressing a constitutively active mutant of FoxO3 in transgenic mice. We generated transgenic mice in which a tetracycline-regulated constitutively active FoxO3 transgene (FoxO3-CA) is controlled by the heart-specific α-myosin heavy chain promoter. Cardiac-specific expression in adult mice resulted in a decrease in heart weight by 25% and a reduction in stroke volume and cardiac output. The decrease in heart size was due to a reduction in the size of individual cardiomyocytes, whereas there was no evidence for increased cell death. FoxO3 activation was accompanied by the initiation of a foetal gene programme with increased expression of β-myosin heavy chain and natriuretic peptides, and by the activation of AKT and mammalian target of rapamycin signalling. As shown by electron microscopy, FoxO3-CA massively stimulated destruction of sarcomeres and autophagy, and induced expression of LC3-II and BNIP3. When FoxO3-CA expression was shut off in affected mice, cardiac atrophy and dysfunction as well as molecular markers were normalized within 1 month. FoxO3-CA expression did not counteract hypertrophy induced by transverse aortic constriction. Heart-specific expression of constitutively active FoxO3 leads to reversible heart atrophy. The reversibility of the phenotype suggests a remarkable ability of the adult myocardium to respond to different regulatory cues.

  20. Macrophages, Inflammation, and Tumor Suppressors: ARF, a New Player in the Game

    Directory of Open Access Journals (Sweden)

    Paqui G. Través

    2012-01-01

    Full Text Available The interaction between tumor progression and innate immune system has been well established in the last years. Indeed, several lines of clinical evidence indicate that immune cells such as tumor-associated macrophages (TAMs interact with tumor cells, favoring growth, angiogenesis, and metastasis of a variety of cancers. In most tumors, TAMs show properties of an alternative polarization phenotype (M2 characterized by the expression of a series of chemokines, cytokines, and proteases that promote immunosuppression, tumor proliferation, and spreading of the cancer cells. Tumor suppressor genes have been traditionally linked to the regulation of cancer progression; however, a growing body of evidence indicates that these genes also play essential roles in the regulation of innate immunity pathways through molecular mechanisms that are still poorly understood. In this paper, we provide an overview of the immunobiology of TAMs as well as what is known about tumor suppressors in the context of immune responses. Recent advances regarding the role of the tumor suppressor ARF as a regulator of inflammation and macrophage polarization are also reviewed.

  1. Macrophages, inflammation, and tumor suppressors: ARF, a new player in the game.

    Science.gov (United States)

    Través, Paqui G; Luque, Alfonso; Hortelano, Sonsoles

    2012-01-01

    The interaction between tumor progression and innate immune system has been well established in the last years. Indeed, several lines of clinical evidence indicate that immune cells such as tumor-associated macrophages (TAMs) interact with tumor cells, favoring growth, angiogenesis, and metastasis of a variety of cancers. In most tumors, TAMs show properties of an alternative polarization phenotype (M2) characterized by the expression of a series of chemokines, cytokines, and proteases that promote immunosuppression, tumor proliferation, and spreading of the cancer cells. Tumor suppressor genes have been traditionally linked to the regulation of cancer progression; however, a growing body of evidence indicates that these genes also play essential roles in the regulation of innate immunity pathways through molecular mechanisms that are still poorly understood. In this paper, we provide an overview of the immunobiology of TAMs as well as what is known about tumor suppressors in the context of immune responses. Recent advances regarding the role of the tumor suppressor ARF as a regulator of inflammation and macrophage polarization are also reviewed.

  2. Tumor suppressor ataxia telangiectasia mutated functions downstream of TGF-β1 in orchestrating profibrotic responses

    NARCIS (Netherlands)

    Overstreet, Jessica M; Samarakoon, Rohan; Cardona-Grau, Diana; Goldschmeding, Roel|info:eu-repo/dai/nl/102376069; Higgins, Paul J

    2015-01-01

    Effective therapy to prevent organ fibrosis, which is associated with more than half of all mortalities, remains elusive. Involvement of tumor suppressor ataxia telangiectasia mutated (ATM) in the TGF-β1 pathway related to renal fibrosis is largely unknown. ATM activation (pATM(Ser1981)) increased 4

  3. Regulation of Notch signaling and endocytosis by the Lgl neoplastic tumor suppressor

    NARCIS (Netherlands)

    Portela, Marta; Parsons, Linda M.; Grzeschik, Nicola A.; Richardson, Helena E.

    2015-01-01

    The evolutionarily conserved neoplastic tumor suppressor protein, Lethal (2) giant larvae (Lgl), plays roles in cell polarity and tissue growth via regulation of the Hippo pathway. In our recent study, we showed that in the developing Drosophila eye epithelium, depletion of Lgl leads to increased li

  4. Very CIN-ful: whole chromosome instability promotes tumor suppressor loss of heterozygosity.

    Science.gov (United States)

    Sotillo, Rocio; Schvartzman, Juan-Manuel; Benezra, Robert

    2009-12-01

    Mechanisms by which whole chromosome instability lead to tumorigenesis have eluded the cancer research field. In this issue of Cancer Cell, Baker et al. show that CIN induced by a defective mitotic checkpoint, under certain genetic and tissue contexts, leads to accelerated loss of heterozygosity of a tumor suppressor gene.

  5. Promoter methylation of PARG1, a novel candidate tumor suppressor gene in mantle-cell lymphomas.

    NARCIS (Netherlands)

    Ripperger, T.; Neuhoff, N. von; Kamphues, K.; Emura, M.; Lehmann, U.; Tauscher, M.; Schraders, M.; Groenen, P.; Skawran, B.; Rudolph, C.; Callet-Bauchu, E.; Krieken, J.H.J.M. van; Schlegelberger, B.; Steinemann, D.

    2007-01-01

    BACKGROUND AND OBJECTIVES: Mantle cell lymphoma (MCL), a mature B-cell neoplasm, is genetically characterized by the translocation t(11;14)(q13;q32). However, secondary alterations are required for malignant transformation. The identification of inactivated tumor suppressor genes contributing to the

  6. Fibronectin is a hypoxia-independent target of the tumor suppressor VHL.

    NARCIS (Netherlands)

    Bluyssen, H.A.; Lolkema, M.P.; Beest, M. van; Boone, M.; Snijckers, C.M.; Los, M.; Gebbink, M.F.; Braam, B.; Holstege, F.C.; Giles, R.H.; Voest, E.E.

    2004-01-01

    The von Hippel-Lindau (VHL) tumor suppressor gene regulates the extracellular matrix by controlling fibronectin deposition. To identify novel VHL target genes, we subjected mRNA from VHL-deficient RCC cells (786-0-pRC) and a transfectant re-expressing wildtype VHL (786-0-VHL) to differential express

  7. NTRK3 is a potential tumor suppressor gene commonly inactivated by epigenetic mechanisms in colorectal cancer.

    Directory of Open Access Journals (Sweden)

    Yanxin Luo

    Full Text Available NTRK3 is a member of the neurotrophin receptor family and regulates cell survival. It appears to be a dependence receptor, and thus has the potential to act as an oncogene or as a tumor suppressor gene. NTRK3 is a receptor for NT-3 and when bound to NT-3 it induces cell survival, but when NT-3 free, it induces apoptosis. We identified aberrantly methylated NTRK3 in colorectal cancers through a genome-wide screen for hypermethylated genes. This discovery led us to assess whether NTRK3 could be a tumor suppressor gene in the colon. NTRK3 is methylated in 60% of colon adenomas and 67% of colon adenocarcinomas. NTRK3 methylation suppresses NTRK3 expression. Reconstitution of NTRK3 induces apoptosis in colorectal cancers, if NT-3 is absent. Furthermore, the loss of NTRK3 expression associates with neoplastic transformation in vitro and in vivo. We also found that a naturally occurring mutant NTRK3 found in human colorectal cancer inhibits the tumor suppressor activity of NTRK3. In summary, our findings suggest NTRK3 is a conditional tumor suppressor gene that is commonly inactivated in colorectal cancer by both epigenetic and genetic mechanisms whose function in the pathogenesis of colorectal cancer depends on the expression status of its ligand, NT-3.

  8. Modulation of junction tension by tumor suppressors and proto-oncogenes regulates cell-cell contacts.

    Science.gov (United States)

    Bosveld, Floris; Guirao, Boris; Wang, Zhimin; Rivière, Mathieu; Bonnet, Isabelle; Graner, François; Bellaïche, Yohanns

    2016-02-15

    Tumor suppressors and proto-oncogenes play crucial roles in tissue proliferation. Furthermore, de-regulation of their functions is deleterious to tissue architecture and can result in the sorting of somatic rounded clones minimizing their contact with surrounding wild-type (wt) cells. Defects in the shape of somatic clones correlate with defects in proliferation, cell affinity, cell-cell adhesion, oriented cell division and cortical contractility. Combining genetics, live-imaging, laser ablation and computer simulations, we aim to analyze whether distinct or similar mechanisms can account for the common role of tumor suppressors and proto-oncogenes in cell-cell contact regulation. In Drosophila epithelia, the tumor suppressors Fat (Ft) and Dachsous (Ds) regulate cell proliferation, tissue morphogenesis, planar cell polarity and junction tension. By analyzing the evolution over time of ft mutant cells and clones, we show that ft clones reduce their cell-cell contacts with the surrounding wt tissue in the absence of concomitant cell divisions and over-proliferation. This contact reduction depends on opposed changes of junction tensions in the clone bulk and its boundary with neighboring wt tissue. More generally, either clone bulk or boundary junction tension is modulated by the activation of Yorkie, Myc and Ras, yielding similar contact reductions with wt cells. Together, our data highlight mechanical roles for proto-oncogene and tumor suppressor pathways in cell-cell interactions.

  9. NTRK3 Is a Potential Tumor Suppressor Gene Commonly Inactivated by Epigenetic Mechanisms in Colorectal Cancer

    Science.gov (United States)

    Luo, Yanxin; Kaz, Andrew M.; Kanngurn, Samornmas; Welsch, Piri; Morris, Shelli M.; Wang, Jianping; Lutterbaugh, James D.; Markowitz, Sanford D.; Grady, William M.

    2013-01-01

    NTRK3 is a member of the neurotrophin receptor family and regulates cell survival. It appears to be a dependence receptor, and thus has the potential to act as an oncogene or as a tumor suppressor gene. NTRK3 is a receptor for NT-3 and when bound to NT-3 it induces cell survival, but when NT-3 free, it induces apoptosis. We identified aberrantly methylated NTRK3 in colorectal cancers through a genome-wide screen for hypermethylated genes. This discovery led us to assess whether NTRK3 could be a tumor suppressor gene in the colon. NTRK3 is methylated in 60% of colon adenomas and 67% of colon adenocarcinomas. NTRK3 methylation suppresses NTRK3 expression. Reconstitution of NTRK3 induces apoptosis in colorectal cancers, if NT-3 is absent. Furthermore, the loss of NTRK3 expression associates with neoplastic transformation in vitro and in vivo. We also found that a naturally occurring mutant NTRK3 found in human colorectal cancer inhibits the tumor suppressor activity of NTRK3. In summary, our findings suggest NTRK3 is a conditional tumor suppressor gene that is commonly inactivated in colorectal cancer by both epigenetic and genetic mechanisms whose function in the pathogenesis of colorectal cancer depends on the expression status of its ligand, NT-3. PMID:23874207

  10. Antiviral activity of tumor-suppressor pathways: clues from molecular piracy by KSHV.

    Science.gov (United States)

    Moore, P S; Chang, Y

    1998-04-01

    A common feature of many tumor viruses is that they possess genes that produce specific proteins to inhibit major cellular tumor-suppressor pathways. Despite intensive studies, the reasons why these diverse and unrelated viruses have independently evolved oncogenes remains obscure. Kaposi-sarcoma-associated herpesvirus (KSHV or HHV8) has pirated a number of recognizable cellular genes that are key to cell survival and proliferation. In this review, we provide an overview of the known activities of these viral genes and show that many of these pirated proteins affect the same cellular pathways targeted by other, unrelated tumor viruses. We speculate that tumor-suppressor pathways are used by the cell as a primary defense against persistent virus infection, in addition to their well-known activity in regulating cell proliferation.

  11. Tumor-derived lactate and myeloid-derived suppressor cells: Linking metabolism to cancer immunology.

    Science.gov (United States)

    Husain, Zaheed; Seth, Pankaj; Sukhatme, Vikas P

    2013-11-01

    Many malignant cells produce increased amounts of lactate, which promotes the development of myeloid-derived suppressor cells (MDSCs). MDSCs, lactate, and a low pH in the tumor microenvironment inhibit the function of natural killer (NK) cells and T lymphocytes, hence allowing for disease progression. Ketogenic diets can deplete tumor-bearing animals from MDSCs and regulatory T cells, thereby improving their immunological profile.

  12. FOXO3 Promotes Quiescence in Adult Muscle Stem Cells during the Process of Self-Renewal

    Directory of Open Access Journals (Sweden)

    Suchitra D. Gopinath

    2014-04-01

    Full Text Available Skeletal muscle stem cells, or “satellite cells” (SCs, are required for the regeneration of damaged muscle tissue. Although SCs self-renew during regeneration, the mechanisms that govern SC re-entry into quiescence remain elusive. We show that FOXO3, a member of the forkhead family of transcription factors, is expressed in quiescent SCs (QSCs. Conditional deletion of Foxo3 in QSCs impairs self-renewal and increases the propensity of SCs to adopt a differentiated fate. Transcriptional analysis of SCs lacking FOXO3 revealed a downregulation of Notch signaling, a key regulator of SC quiescence. Conversely, overexpression of Notch intracellular domain (NICD rescued the self-renewal deficit of FOXO3-deficient SCs. We show that FOXO3 regulates NOTCH1 and NOTCH3 receptor expression and that decreasing expression of NOTCH1 and NOTCH3 receptors phenocopies the effect of FOXO3 deficiency in SCs. We demonstrate that FOXO3, perhaps by activating Notch signaling, promotes the quiescent state during SC self-renewal in adult muscle regeneration.

  13. Epidermal growth factor receptor mediated proliferation depends on increased lipid droplet density regulated via a negative regulatory loop with FOXO3/Sirtuin6

    Energy Technology Data Exchange (ETDEWEB)

    Penrose, Harrison; Heller, Sandra; Cable, Chloe [Department of Pathology and Laboratory Medicine, Tulane University School of Medicine, 1430 Tulane Ave SL-79, New Orleans, LA 70112 (United States); Makboul, Rania [Department of Pathology and Laboratory Medicine, Tulane University School of Medicine, 1430 Tulane Ave SL-79, New Orleans, LA 70112 (United States); Pathology Department, Assiut University, Assiut (Egypt); Chadalawada, Gita; Chen, Ying [Department of Pathology and Laboratory Medicine, Tulane University School of Medicine, 1430 Tulane Ave SL-79, New Orleans, LA 70112 (United States); Crawford, Susan E. [Department of Pathology, Saint Louis University School of Medicine, 1402 South Grand Blvd, Saint Louis, MO 63104 (United States); Savkovic, Suzana D., E-mail: ssavkovi@tulane.edu [Department of Pathology and Laboratory Medicine, Tulane University School of Medicine, 1430 Tulane Ave SL-79, New Orleans, LA 70112 (United States)

    2016-01-15

    The proliferation of colon cancer cells is mediated in part by epidermal growth factor receptor (EGFR) signaling and requires sustained levels of cellular energy to meet its high metabolic needs. Intracellular lipid droplets (LDs) are a source of energy used for various cellular functions and they are elevated in density in human cancer, yet their regulation and function are not well understood. Here, in human colon cancer cells, EGF stimulates increases in LD density, which depends on EGFR expression and activation as well as the individual cellular capacity for lipid synthesis. Increases in LDs are blockaded by inhibition of PI3K/mTOR and PGE2 synthesis, supporting their dependency on select upstream pathways. In colon cancer cells, silencing of the FOXO3 transcription factor leads to down regulation of SIRT6, a negative regulator of lipid synthesis, and consequent increases in the LD coat protein PLIN2, revealing that increases in LDs depend on loss of FOXO3/SIRT6. Moreover, EGF stimulates loss of FOXO3/SIRT6, which is blockaded by the inhibition of upstream pathways as well as lipid synthesis, revealing existence of a negative regulatory loop between LDs and FOXO3/SIRT6. Elevated LDs are utilized by EGF treatment and their depletion through the inhibition of lipid synthesis or silencing of PLIN2 significantly attenuates proliferation. This novel mechanism of proliferative EGFR signaling leading to elevated LD density in colon cancer cells could potentially be therapeutically targeted for the treatment of tumor progression. - Highlights: • In colon cancer cells, EGFR activation leads to increases in LD density. • EGFR signaling includes PI3K/mTOR and PGE2 leading to lipid synthesis. • Increases in LDs are controlled by a negative regulatory loop with FOXO3/SIRT6. • EGFR mediated colon cancer cell proliferation depends on increased LD density.

  14. Alterations of tumor suppressor and tumor-related genes in the development and progression of gastric cancer

    Institute of Scientific and Technical Information of China (English)

    Gen Tamura

    2006-01-01

    The development and progression of gastric cancer involves a number of genetic and epigenetic alterations of tumor suppressor and tumor-related genes. The majority of differentiated carcinomas arise from intestinal metaplastic mucosa and exhibit structurally altered tumor suppressor genes, typified by p53,which is inactivated via the classic two-hit mechanism,i.e. loss of heterozygosity (LOH) and mutation of the remaining allele. LOH at certain chromosomal loci accumulates during tumor progression. Approximately 20% of differentiated carcinomas show evidence of mutator pathway tumorigenesis due to hMLH1inactivation via hypermethylation of promoter CpG islands, and exhibit high-frequency microsatellite instability. In contrast, undifferentiated carcinomas rarely exhibit structurally altered tumor suppressor genes. For instance, while methylation of E-cadherin is often observed in undifferentiated carcinomas,mutation of this gene is generally associated with the progression from differentiated to undifferentiated carcinomas. Hypermethylation of tumor suppressor and tumor-related genes, including APC, CHFR, DAP-kinase, DCC, E-cadherin, GSTP1, hMLH1, p16, PTEN,RASSF1A, RUNX3, and TSLC1, can be detected in both differentiated and undifferentiated carcinomas at varying frequencies. However, the significance of the hypermethylation varies according to the analyzed genomic region, and hypermethylation of these genes can also be present in non-neoplastic gastric epithelia.Promoter demethylation of specific genes, such as MAGE and synuclein y, can occur during the progressive stages of both histological types, and is associated with patient prognosis. Thus, while the molecular pathways of gastric carcinogenesis are dependent on histological background, specific genetic alterations can still be used for risk assessment, diagnosis, and prognosis.

  15. Deciphering tumor-suppressor signaling in flies: Genetic link between Scribble/Dlg/Lgl and the Hippo pathways

    Institute of Scientific and Technical Information of China (English)

    Masato Enomoto; Tatsushi Igaki

    2011-01-01

    Loss of apico-basal polarity is one of the crucial factors that drives epithelial tumor progression.scribble/discs large/lethal giant larvae (scrib/dlg/lgl),a group of apico-basal polarity genes,were initially identified as members of “neoplastic” tumor-suppressors in flies.The components of the Hippo signaling pathway,which is crucial for organ size control and cancer development,were also identified through Drosophila genetic screens as members of “hyperplastic” tumor-suppressors.Accumulating evidence in recent studies implies that these two tumor-suppressor signaling pathways are not mutually exclusive but rather cooperatively act to give rise to highly malignant tumors.The interaction of these tumor-suppressor pathways could include deregulations of actin cytoskeleton,cell-cell contact,and apical-domain size of the epithelial cell.

  16. RNA-DNA differences are rarer in proto-oncogenes than in tumor suppressor genes.

    Science.gov (United States)

    Gao, Feng; Lin, Yan; Zhang, Randy Ren

    2012-01-01

    It has long been assumed that DNA sequences and corresponding RNA transcripts are almost identical; a recent discovery, however, revealed widespread RNA-DNA differences (RDDs), which represent a largely unexplored aspect of human genome variation. It has been speculated that RDDs can affect disease susceptibility and manifestations; however, almost nothing is known about how RDDs are related to disease. Here, we show that RDDs are rarer in proto-oncogenes than in tumor suppressor genes; the number of RDDs in coding exons, but not in 3'UTR and 5'UTR, is significantly lower in the former than the latter, and this trend is especially pronounced in non-synonymous RDDs, i.e., those cause amino acid changes. A potential mechanism is that, unlike proto-oncogenes, the requirement of tumor suppressor genes to have both alleles affected to cause tumor 'buffers' these genes to tolerate more RDDs.

  17. CMTM5 exhibits tumor suppressor activity through promoter methylation in oral squamous cell carcinoma

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Heyu [Central Laboratory, Peking University School of Stomatology, Beijing (China); Nan, Xu [Center for Human Disease Genomics, Department of Immunology, Key Laboratory of Medical Immunology, Ministry of Health, School of Basic Medical Sciences, Peking University, Beijing (China); Li, Xuefen [Central Laboratory, Peking University School of Stomatology, Beijing (China); Chen, Yan; Zhang, Jianyun [Department of Oral Pathology, Peking University School of Stomatology, Beijing (China); Sun, Lisha [Central Laboratory, Peking University School of Stomatology, Beijing (China); Han, Wenlin [Center for Human Disease Genomics, Department of Immunology, Key Laboratory of Medical Immunology, Ministry of Health, School of Basic Medical Sciences, Peking University, Beijing (China); Li, Tiejun, E-mail: litiejun22@vip.sina.com [Department of Oral Pathology, Peking University School of Stomatology, Beijing (China)

    2014-05-02

    Highlights: • Down-regulation of CMTM5 expression in OSCC tissues was found. • The promoter methylation status of CMTM5 was measured. • CMTM5-v1 inhibited cell proliferation and migration and induced apoptosis. • CMTM5 might act as a putative tumor suppressor gene in OSCC. - Abstract: Oral squamous cell carcinoma (OSCC) is one of the most common types of malignancies in the head and neck region. CKLF-like MARVEL transmembrane domain-containing member 5 (CMTM5) has been recently implicated as a tumor suppressor gene in several cancer types. Herein, we examined the expression and function of CMTM5 in oral squamous cell carcinoma. CMTM5 was down-regulated in oral squamous cell lines and tumor samples from patients with promoter methylation. Treatment with the demethylating agent 5-aza-2′-deoxycytidine restored CMTM5 expression. In the OSCC cell lines CAL27 and GNM, the ectopic expression of CMTM5-v1 strongly inhibited cell proliferation and migration and induced apoptosis. In addition, CMTM5-v1 inhibited tumor formation in vivo. Therefore, CMTM5 might act as a putative tumor suppressor gene through promoter methylation in oral squamous cell carcinoma.

  18. RASSF10 is epigenetically silenced and functions as a tumor suppressor in gastric cancer

    Energy Technology Data Exchange (ETDEWEB)

    Wei, Ziran [Department of General Surgery, Shanghai Changzheng Hospital, Second Military Medical University, Shanghai (China); Chen, Xia [Urology Department, Minhang District Central Hospital, Shanghai (China); Chen, Ji; Wang, Weimin [Department of General Surgery, Shanghai Changzheng Hospital, Second Military Medical University, Shanghai (China); Xu, Xudong [Urology Department, Minhang District Central Hospital, Shanghai (China); Cai, Qingping, E-mail: qingping_caicz@163.com [Department of General Surgery, Shanghai Changzheng Hospital, Second Military Medical University, Shanghai (China)

    2013-03-22

    Highlights: ► Epigenetic silencing of RASSF10 gene expression in GC cells. ► RASSF10 overexpression inhibits cell growth in vitro and in vivo. ► RASSF10 induces apoptosis in GC cells. ► RASSF10 inhibits Wnt/β-catenin signaling pathway. -- Abstract: Ras association domain family (RASSF) proteins are encoded by several tumor suppressor genes that are frequently silenced in human cancers. In this study, we investigated RASSF10 as a target of epigenetic inactivation and examined its functions as a tumor suppressor in gastric cancer. RASSF10 was silenced in six out of eight gastric cancer cell lines. Loss or downregulation of RASSF10 expression was associated with promoter hypermethylation, and could be restored by a demethylating agent. Overexpression of RASSF10 in gastric cancer cell lines (JRST, BGC823) suppressed cell growth and colony formation, and induced apoptosis, whereas RASSF10 depletion promoted cell growth. In xenograft animal experiments, RASSF10 overexpression effectively repressed tumor growth. Mechanistic investigations revealed that RASSF10 inhibited tumor growth by blocking activation of β-catenin and its downstream targets including c-Myc, cyclinD1, cyclinE1, peroxisome proliferator-activated receptor δ, transcription factor 4, transcription factor 1 and CD44. In conclusion, the results of this study provide insight into the role of RASSF10 as a novel functional tumor suppressor in gastric cancer through inhibition of the Wnt/β-catenin signaling pathway.

  19. Characterization of DOK1, a candidate tumor suppressor gene, in epithelial ovarian cancer.

    Science.gov (United States)

    Mercier, Pierre-Luc; Bachvarova, Magdalena; Plante, Marie; Gregoire, Jean; Renaud, Marie-Claude; Ghani, Karim; Têtu, Bernard; Bairati, Isabelle; Bachvarov, Dimcho

    2011-10-01

    In attempt to discover novel aberrantly hypermethylated genes with putative tumor suppressor function in epithelial ovarian cancer (EOC), we applied expression profiling following pharmacologic inhibition of DNA methylation in EOC cell lines. Among the genes identified, one of particular interest was DOK1, or downstream of tyrosine kinase 1, previously recognized as a candidate tumor suppressor gene (TSG) for leukemia and other human malignancies. Using bisulfite sequencing, we determined that a 5'-non-coding DNA region (located at nt -1158 to -850, upstream of the DOK1 translation start codon) was extensively hypermethylated in primary serous EOC tumors compared with normal ovarian specimens; however, this hypermethylation was not associated with DOK1 suppression. On the contrary, DOK1 was found to be strongly overexpressed in serous EOC tumors as compared to normal tissue and importantly, DOK1 overexpression significantly correlated with improved progression-free survival (PFS) values of serous EOC patients. Ectopic modulation of DOK1 expression in EOC cells and consecutive functional analyses pointed toward association of DOK1 expression with increased EOC cell migration and proliferation, and better sensitivity to cisplatin treatment. Gene expression profiling and consecutive network and pathway analyses were also confirmative for DOK1 association with EOC cell migration and proliferation. These analyses were also indicative for DOK1 protective role in EOC tumorigenesis, linked to DOK1-mediated induction of some tumor suppressor factors and its suppression of pro-metastasis genes. Taken together, our findings are suggestive for a possible tumor suppressor role of DOK1 in EOC; however its implication in enhanced EOC cell migration and proliferation restrain us to conclude that DOK1 represents a true TSG in EOC. Further studies are needed to more completely elucidate the functional implications of DOK1 and other members of the DOK gene family in ovarian

  20. Myeloid-derived suppressor cell role in tumor-related inflammation.

    Science.gov (United States)

    Dolcetti, Luigi; Marigo, Ilaria; Mantelli, Barbara; Peranzoni, Elisa; Zanovello, Paola; Bronte, Vincenzo

    2008-08-28

    Chronic inflammatory state can create a proper environment for neoplastic onset and sustain cancer growth. The inflammatory state that arises at the tumor edge could contribute to immune escape phenomena in many ways. Myeloid-derived suppressor cells (MDSCs), a cell population that contributes to tumor escape, immune tolerance, and suppression, respond to a variety of pro-inflammatory and anti-inflammatory stimuli, which drive their recruitment and activation. Understanding how the inflammatory milieu favours tumor escape through the accumulation of MDSCs could be very useful to improve the efficacy of cancer immunotherapy.

  1. Isolation of Breast Tumor Suppressor Genes from Chromosome 11p

    Science.gov (United States)

    2001-09-01

    at chromosome crucial role in urogenital development (Pelletier et al., llp15 has also been described in Wilms tumors but thus 1991). However...Atkins L and Riccardi VM. (1979). Nowak NJ, Evans G, Stanbridge EJ, de Jong P, Shows TB , Cytogenet. Cell Genet., 24, 185-192. Weissman BE and Higgins MJ...Singh-Kahlon P, Weksberg R, Squire J, Grundy P, Coppes MJ and Haber D. (1995). Hematology/ Shows TB and Higgins MJ. (1994). Genes Chromosomes Oncology

  2. The vitamin D receptor: a tumor suppressor in skin.

    Science.gov (United States)

    Bikle, Daniel D

    2014-01-01

    Cutaneous malignancies including melanomas and non melanoma skin cancers (NMSC) are the most common types of cancer, occurring at a rate of over 1 million per year in the United States. The major cell in the epidermis, the keratinocyte, not only produces vitamin D but contains the enzymatic machinery to metabolize vitamin D to its active metabolite, 1,25(OH)2D, and expresses the receptor for this metabolite, the vitamin D receptor (VDR), allowing the cell to respond to the 1,25(OH)2D that it produces. In vitro, 1,25(OH)2D stimulates the differentiation and inhibits the proliferation of these cells and so would be expected to be tumor suppressive. However, epidemiologic evidence demonstrating a negative relationship between circulating levels of the substrate for CYP27B1, 25OHD, and the incidence of these malignancies is mixed, raising the question whether vitamin D is protective in the in vivo setting. UV radiation (UV), both UVB and UVA, as occurs with sunlight exposure is generally regarded as causal for these malignancies, but UVB is also required for vitamin D synthesis in the skin. This complicates conclusions reached from epidemiologic studies in that UVB is associated with higher 25OHD levels as well as increased incidence of cutaneous malignancies. Based on our own data and that reported in the literature we hypothesize that vitamin D signaling in the skin suppresses UVR induced epidermal tumor formation. In this chapter we will first discuss recent data regarding potential mechanisms by which vitamin D signaling suppresses tumor formation, then focus on three general mechanisms that mediate tumor suppression by VDR in the skin: inhibition of proliferation and stimulation of differentiation, immune regulation, and stimulation of DNA damage repair (DDR).

  3. Modulation and Expression of Tumor Suppressor Genes by Environmental Agents.

    Science.gov (United States)

    1996-12-01

    Den Otter 1990). In a preliminary report (Windle et al. 1990), a transgenic mouse that develops intraocular neoplasms similar to human retinoblastoma...et al. 1974; McFall et al. 1978; Bogenmann and Mark 1983), and a very recent report of heritable ocular tumors in transgenic mice (Windle et al. 1990...additional pair of forceps (fine Halstead Mosquito hemostatic curved forceps 12.7 cm) were used to clamp off the retracted liver transversely just anterior to

  4. miR-137 Modulates a Tumor Suppressor Network-Inducing Senescence in Pancreatic Cancer Cells

    Directory of Open Access Journals (Sweden)

    Mathieu Neault

    2016-03-01

    Full Text Available Activating K-Ras mutations occurs frequently in pancreatic cancers and is implicated in their development. Cancer-initiating events, such as oncogenic Ras activation, lead to the induction of cellular senescence, a tumor suppressor response. During senescence, the decreased levels of KDM4A lysine demethylase contribute to p53 activation, however, the mechanism by which KDM4A is downregulated is unknown. We show that miR-137 targets KDM4A mRNA during Ras-induced senescence and activates both p53 and retinoblastoma (pRb tumor suppressor pathways. Restoring the KDM4A expression contributed to bypass of miR-137-induced senescence and inhibition of endogenous miR-137 with an miRNA sponge-compromised Ras-induced senescence. miR-137 levels are significantly reduced in human pancreatic tumors, consistent with previous studies revealing a defective senescence response in this cancer type. Restoration of miR-137 expression inhibited proliferation and promoted senescence of pancreatic cancer cells. These results suggest that modulating levels of miR-137 may be important for triggering tumor suppressor networks in pancreatic cancer.

  5. Distinct tumor suppressor mechanisms evolve in rodent species that differ in size and lifespan

    Science.gov (United States)

    Seluanov, Andrei; Hine, Christopher; Bozzella, Michael; Hall, Amelia; Sasahara, Tais H. C.; Ribeiro, Antonio A. C. M.; Catania, Kenneth C.; Presgraves, Daven C.; Gorbunova, Vera

    2008-01-01

    SUMMARY Large, long-lived species experience more lifetime cell divisions and hence a greater risk of spontaneous tumor formation than smaller, short-lived species. Large, long-lived species are thus expected to evolve more elaborate tumor suppressor systems. In previous work, we showed that telomerase activity coevolves with body mass, but not lifespan, in rodents: telomerase activity is repressed in the somatic tissues of large rodent species but remains active in small ones. Without telomerase activity, the telomeres of replicating cells become progressively shorter until, at some critical length, cells stop dividing. Our findings therefore suggested that repression of telomerase activity mitigates the increased risk of cancer in larger bodied species but not necessarily longer-lived ones. These findings imply that other tumor suppressor mechanisms must mitigate increased cancer risk in long-lived species. Here, we examined the proliferation of fibroblasts from 15 rodent species with diverse body sizes and lifespans. We show that, consistent with repressed telomerase activity, fibroblasts from large rodents undergo replicative senescence accompanied by telomere shortening and overexpression of p16Ink4a and p21Cip1/Waf1 cycline dependent kinase inhibitors. Interestingly, small rodents with different lifespans show a striking difference: cells from small shorter-lived species display continuous rapid proliferation, whereas cells from small long-lived species display continuous slow proliferation. We hypothesize that cells of small long-lived rodents, lacking replicative senescence, have evolved alternative tumor-suppressor mechanisms that prevent inappropriate cell division in vivo and slow cell growth in vitro. Thus, large-bodied species and small but long-lived species have evolved distinct tumor suppressor mechanisms. PMID:18778411

  6. Mutational screening of FOXO3A and FOXO1A in women with premature ovarian failure.

    Science.gov (United States)

    Watkins, Wendy J; Umbers, Alexandra J; Woad, Kathryn J; Harris, Sarah E; Winship, Ingrid M; Gersak, Ksenija; Shelling, Andrew N

    2006-11-01

    FOXO3A and FOXO1A are excellent candidate genes for the development of premature ovarian failure and have not been analyzed previously in POF patients. Potentially causal mutations in FOXO3A (2/90; 2.2%) and FOXO1A (1/90; 1.1%) were identified in POF patients; however, the pathological role of these mutations will be determined only by screening increased numbers of patients and controls, or by functional studies.

  7. FOXO3a regulates BNIP3 and modulates mitochondrial calcium, dynamics, and function in cardiac stress.

    Science.gov (United States)

    Chaanine, Antoine H; Kohlbrenner, Erik; Gamb, Scott I; Guenzel, Adam J; Klaus, Katherine; Fayyaz, Ahmed U; Nair, K Sreekumaran; Hajjar, Roger J; Redfield, Margaret M

    2016-12-01

    The forkhead box O3a (FOXO3a) transcription factor has been shown to regulate glucose metabolism, muscle atrophy, and cell death in postmitotic cells. Its role in regulation of mitochondrial and myocardial function is not well studied. Based on previous work, we hypothesized that FOXO3a, through BCL2/adenovirus E1B 19-kDa protein-interacting protein 3 (BNIP3), modulates mitochondrial morphology and function in heart failure (HF). We modulated the FOXO3a-BNIP3 pathway in normal and phenylephrine (PE)-stressed adult cardiomyocytes (ACM) in vitro and developed a cardiotropic adeno-associated virus serotype 9 encoding dominant-negative FOXO3a (AAV9.dn-FX3a) for gene delivery in a rat model of HF with preserved ejection fraction (HFpEF). We found that FOXO3a upregulates BNIP3 expression in normal and PE-stressed ACM, with subsequent increases in mitochondrial Ca(2+), leading to decreased mitochondrial membrane potential, mitochondrial fragmentation, and apoptosis. Whereas dn-FX3a attenuated the increase in BNIP3 expression and its consequences in PE-stressed ACM, AAV9.dn-FX3a delivery in an experimental model of HFpEF decreased BNIP3 expression, reversed adverse left ventricular remodeling, and improved left ventricular systolic and, particularly, diastolic function, with improvements in mitochondrial structure and function. Moreover, AAV9.dn-FX3a restored phospholamban phosphorylation at S16 and enhanced dynamin-related protein 1 phosphorylation at S637. Furthermore, FOXO3a upregulates maladaptive genes involved in mitochondrial apoptosis, autophagy, and cardiac atrophy. We conclude that FOXO3a activation in cardiac stress is maladaptive, in that it modulates Ca(2+) cycling, Ca(2+) homeostasis, and mitochondrial dynamics and function. Our results suggest an important role of FOXO3a in HF, making it an attractive potential therapeutic target. Copyright © 2016 the American Physiological Society.

  8. Mechanical unloading activates FoxO3 to trigger Bnip3-dependent cardiomyocyte atrophy.

    Science.gov (United States)

    Cao, Dian J; Jiang, Nan; Blagg, Andrew; Johnstone, Janet L; Gondalia, Raj; Oh, Misook; Luo, Xiang; Yang, Kai-Chun; Shelton, John M; Rothermel, Beverly A; Gillette, Thomas G; Dorn, Gerald W; Hill, Joseph A

    2013-04-08

    Mechanical assist device therapy has emerged recently as an important and rapidly expanding therapy in advanced heart failure, triggering in some patients a beneficial reverse remodeling response. However, mechanisms underlying this benefit are unclear. In a model of mechanical unloading of the left ventricle, we observed progressive myocyte atrophy, autophagy, and robust activation of the transcription factor FoxO3, an established regulator of catabolic processes in other cell types. Evidence for FoxO3 activation was similarly detected in unloaded failing human myocardium. To determine the role of FoxO3 activation in cardiac muscle in vivo, we engineered transgenic mice harboring a cardiomyocyte-specific constitutively active FoxO3 mutant (caFoxO3(flox);αMHC-Mer-Cre-Mer). Expression of caFoxO3 triggered dramatic and progressive loss of cardiac mass, robust increases in cardiomyocyte autophagy, declines in mitochondrial biomass and function, and early mortality. Whereas increases in cardiomyocyte apoptosis were not apparent, we detected robust increases in Bnip3 (Bcl2/adenovirus E1B 19-kDa interacting protein 3), an established downstream target of FoxO3. To test the role of Bnip3, we crossed the caFoxO3(flox);αMHC-Mer-Cre-Mer mice with Bnip3-null animals. Remarkably, the atrophy and autophagy phenotypes were significantly blunted, yet the early mortality triggered by FoxO3 activation persisted. Rather, declines in cardiac performance were attenuated by proteasome inhibitors. Consistent with involvement of FoxO3-driven activation of the ubiquitin-proteasome system, we detected time-dependent activation of the atrogenes program and sarcomere protein breakdown. In aggregate, these data point to FoxO3, a protein activated by mechanical unloading, as a master regulator that governs both the autophagy-lysosomal and ubiquitin-proteasomal pathways to orchestrate cardiac muscle atrophy.

  9. Mechanical Unloading Activates FoxO3 to Trigger Bnip3‐Dependent Cardiomyocyte Atrophy

    Science.gov (United States)

    Cao, Dian J.; Jiang, Nan; Blagg, Andrew; Johnstone, Janet L.; Gondalia, Raj; Oh, Misook; Luo, Xiang; Yang, Kai‐Chun; Shelton, John M.; Rothermel, Beverly A.; Gillette, Thomas G.; Dorn, Gerald W.; Hill, Joseph A.

    2013-01-01

    Background Mechanical assist device therapy has emerged recently as an important and rapidly expanding therapy in advanced heart failure, triggering in some patients a beneficial reverse remodeling response. However, mechanisms underlying this benefit are unclear. Methods and Results In a model of mechanical unloading of the left ventricle, we observed progressive myocyte atrophy, autophagy, and robust activation of the transcription factor FoxO3, an established regulator of catabolic processes in other cell types. Evidence for FoxO3 activation was similarly detected in unloaded failing human myocardium. To determine the role of FoxO3 activation in cardiac muscle in vivo, we engineered transgenic mice harboring a cardiomyocyte‐specific constitutively active FoxO3 mutant (caFoxO3flox;αMHC‐Mer‐Cre‐Mer). Expression of caFoxO3 triggered dramatic and progressive loss of cardiac mass, robust increases in cardiomyocyte autophagy, declines in mitochondrial biomass and function, and early mortality. Whereas increases in cardiomyocyte apoptosis were not apparent, we detected robust increases in Bnip3 (Bcl2/adenovirus E1B 19‐kDa interacting protein 3), an established downstream target of FoxO3. To test the role of Bnip3, we crossed the caFoxO3flox;αMHC‐Mer‐Cre‐Mer mice with Bnip3‐null animals. Remarkably, the atrophy and autophagy phenotypes were significantly blunted, yet the early mortality triggered by FoxO3 activation persisted. Rather, declines in cardiac performance were attenuated by proteasome inhibitors. Consistent with involvement of FoxO3‐driven activation of the ubiquitin‐proteasome system, we detected time‐dependent activation of the atrogenes program and sarcomere protein breakdown. Conclusions In aggregate, these data point to FoxO3, a protein activated by mechanical unloading, as a master regulator that governs both the autophagy‐lysosomal and ubiquitin‐proteasomal pathways to orchestrate cardiac muscle atrophy. PMID:23568341

  10. The influence of tumor immunity suppressors on the effector stage of human and animal lymphokine-activated killer cells.

    Science.gov (United States)

    Abronina, I F; Indrova, M; Bubenic, J; Figurin, K M; Malakhova, N V; Bykovskaya, S N

    1993-01-01

    Spleen cells of tumor-bearing mice suppressed the cytolytic activity of syngeneic LAK cells when added to the mixture of LAK cells and target cells at the beginning of the cytotoxicity test. Spleen cells of MC 14 tumor-bearing mice acquired the suppressor potential as early as 10 days after tumor transplantation; the suppressor activity in the EL 4 and X63-Ag8.653 tumor-bearing animals was first revealed at the 30th day and manifested itself up to the 120th day. The suppressor activity was expressed in a dose-dependent manner, both by unfractionated spleen cells and nylon wool-passed and plastic-adherent sub-populations. Similar results were obtained during the analysis of anti-tumor immunity suppressors in bladder cancer patients. MNC, nylon wool-passed and plastic-adherent cells of patients with stages I-II disease suppressed the cytotoxicity of autologous LAK cells in 2/6 cases; all patients [4] with III-IV stage possessed such suppressor activity. Presumably, the tumor growth induces the activity of suppressor T cells and monocytes/macrophages. The suppressor activity can interfere with the antitumor effect of autologous (syngeneic) LAK cells at the effector stage.

  11. OPCML is a broad tumor suppressor for multiple carcinomas and lymphomas with frequently epigenetic inactivation.

    Directory of Open Access Journals (Sweden)

    Yan Cui

    Full Text Available Identification of tumor suppressor genes (TSGs silenced by CpG methylation uncovers the molecular mechanism of tumorigenesis and potential tumor biomarkers. Loss of heterozygosity at 11q25 is common in multiple tumors including nasopharyngeal carcinoma (NPC. OPCML, located at 11q25, is one of the downregulated genes we identified through digital expression subtraction.Semi-quantitative RT-PCR showed frequent OPCML silencing in NPC and other common tumors, with no homozygous deletion detected by multiplex differential DNA-PCR. Instead, promoter methylation of OPCML was frequently detected in multiple carcinoma cell lines (nasopharyngeal, esophageal, lung, gastric, colon, liver, breast, cervix, prostate, lymphoma cell lines (non-Hodgkin and Hodgkin lymphoma, nasal NK/T-cell lymphoma and primary tumors, but not in any non-tumor cell line and seldom weakly methylated in normal epithelial tissues. Pharmacological and genetic demethylation restored OPCML expression, indicating a direct epigenetic silencing. We further found that OPCML is stress-responsive, but this response is epigenetically impaired when its promoter becomes methylated. Ecotopic expression of OPCML led to significant inhibition of both anchorage-dependent and -independent growth of carcinoma cells with endogenous silencing.Thus, through functional epigenetics, we identified OPCML as a broad tumor suppressor, which is frequently inactivated by methylation in multiple malignancies.

  12. Tumor suppressor WWOX and p53 alterations and drug resistance in glioblastomas

    Directory of Open Access Journals (Sweden)

    Ming-Fu eChiang

    2013-03-01

    Full Text Available Tumor suppressor p53 are frequently mutated in glioblastomas (GBMs and appears to contribute, in part, to resistance to temozolomide and therapeutic drugs. WW domain-containing oxidoreductase WWOX (FOR or WOX1 is a proapoptotic protein and is considered as a tumor suppressor. Loss of WWOX gene expression is frequently seen in malignant cancer cells due to promoter hypermethylation, genetic alterations, and translational blockade. Intriguingly, ectopic expression of wild type WWOX preferentially induces apoptosis in human glioblastoma cells harboring mutant p53. WWOX is known to physically bind and stabilize wild type p53. Here, we provide an overview for the updated knowledge in p53 and WWOX, and postulate a potential scenarios that wild type and mutant p53, or isoforms, modulate the apoptotic function of WWOX. We propose that triggering WWOX activation by therapeutic drugs under p53 functional deficiency is needed to overcome TMZ resistance and induce GBM cell death.

  13. Activation of β-catenin/TCF targets following loss of the tumor suppressor SNF5.

    Science.gov (United States)

    Mora-Blanco, E L; Mishina, Y; Tillman, E J; Cho, Y-J; Thom, C S; Pomeroy, S L; Shao, W; Roberts, C W M

    2014-02-13

    The SWI/SNF chromatin remodeling complex is a master regulator of developmental cell-fate decisions, although the key target pathways are poorly characterized. Here, we interrogated the contribution of the SWI/SNF subunit and tumor suppressor SNF5 to the regulation of developmental pathways using conditional mouse and cell culture models. We find that loss of SNF5 phenocopies β-catenin hyperactivation and that SNF5 is essential for regulating Wnt/β-catenin pathway target expression. These data provide insight into chromatin-based mechanisms that underlie developmental regulation and elucidate the emerging theme that mutation of this tumor suppressor complex can activate developmental pathways by uncoupling them from upstream control.

  14. MLL3 is a haploinsufficient 7q tumor suppressor in acute myeloid leukemia.

    Science.gov (United States)

    Chen, Chong; Liu, Yu; Rappaport, Amy R; Kitzing, Thomas; Schultz, Nikolaus; Zhao, Zhen; Shroff, Aditya S; Dickins, Ross A; Vakoc, Christopher R; Bradner, James E; Stock, Wendy; LeBeau, Michelle M; Shannon, Kevin M; Kogan, Scott; Zuber, Johannes; Lowe, Scott W

    2014-05-12

    Recurring deletions of chromosome 7 and 7q [-7/del(7q)] occur in myelodysplastic syndromes and acute myeloid leukemia (AML) and are associated with poor prognosis. However, the identity of functionally relevant tumor suppressors on 7q remains unclear. Using RNAi and CRISPR/Cas9 approaches, we show that an ∼50% reduction in gene dosage of the mixed lineage leukemia 3 (MLL3) gene, located on 7q36.1, cooperates with other events occurring in -7/del(7q) AMLs to promote leukemogenesis. Mll3 suppression impairs the differentiation of HSPC. Interestingly, Mll3-suppressed leukemias, like human -7/del(7q) AMLs, are refractory to conventional chemotherapy but sensitive to the BET inhibitor JQ1. Thus, our mouse model functionally validates MLL3 as a haploinsufficient 7q tumor suppressor and suggests a therapeutic option for this aggressive disease.

  15. Effect of hydroxyurea on the promoter occupancy profiles of tumor suppressor p53 and p73

    OpenAIRE

    2009-01-01

    Abstract Background The p53 tumor suppressor and its related protein, p73, share a homologous DNA binding domain, and mouse genetics studies have suggested that they have overlapping as well as distinct biological functions. Both p53 and p73 are activated by genotoxic stress to regulate an array of cellular responses. Previous studies have suggested that p53 and p73 independently activate the cellular apoptotic program in response to cytotoxic drugs. The goal of this study was to compare the ...

  16. Role of the Rb and p53 Tumor Suppressor Pathways in Mammary Tumorigenesis

    Science.gov (United States)

    2012-09-01

    kinase screen and off-patent drug screen) REPORTABLE OUTCOMES Jones, Robert., Jiang, Zhe ., Deng, Tao., Schimmer, AD., Moffat, J and...Robert., Jiang, Zhe ., Deng, Tao., Schimmer, AD., Moffat, J and Zacksenhaus, E. Role of the RB and p53 tumor suppressor pathways in mammary tumorigenesis...CDMRP 2011 Era of Hope Conference Jiang Z, Jones R, Liu JC, Deng T, Robinson T, Chung PE, Wang S, Herschkowitz Jl, Egan SE, Perou CM

  17. MicroRNA-34a is a potent tumor suppressor molecule in vivo in neuroblastoma.

    LENUS (Irish Health Repository)

    Tivnan, Amanda

    2011-01-01

    Neuroblastoma is a paediatric cancer which originates from precursor cells of the sympathetic nervous system and accounts for 15% of childhood cancer mortalities. With regards to the role of miRNAs in neuroblastoma, miR-34a, mapping to a chromosome 1p36 region that is commonly deleted, has been found to act as a tumor suppressor through targeting of numerous genes associated with cell proliferation and apoptosis.

  18. Markers for sebaceoma show a spectrum of cell cycle regulators, tumor suppressor genes, and oncogenes

    Directory of Open Access Journals (Sweden)

    Ana Maria Abreu Velez

    2015-01-01

    Full Text Available Background: Sebaceoma is a tumor for which the causative oncogenes are not well-understood. Sebaceomas demonstrate some histopathologic features similar to basal cell carcinoma (BCC, such as palisading borders and basaloid cells with additional features, including foamy cytoplasm and indented nuclei. Aims: We examine multiple cell-cycle, oncogene, and tumor suppressor gene markers in sebaceomas, to try to find some suitable biological markers for this tumor, and compare with other published studies. Materials and Methods: We investigated a panel of immunohistochemical (IHC stains that are important for cellular signaling, including a cell cycle regulator, tumor suppressor gene, oncogene, hormone receptor, and genomic stability markers in our cohort of sebaceomas. We collected 30 sebaceomas from three separate USA dermatopathology laboratories. The following IHC panel: Epithelial membrane antigen (EMA/CD227, cytokeratin AE1/AE3, cyclin D1, human breast cancer 1 protein (BRCA-1, C-erb-2, Bcl-2, human androgen receptor (AR, cyclin-dependent kinase inhibitor 1B (p27 kip1 , p53, topoisomerase II alpha, proliferating cell nuclear antigen, and Ki-67 were tested in our cases. Results: EMA/CD227 was positive in the well-differentiated sebaceomas (13/30. Cyclin-dependent kinase inhibitor 1B was positive in tumors with intermediate differentiation (22/30. The less well-differentiated tumors failed to stain with EMA and AR. Most of the tumors with well-differentiated palisaded areas demonstrated positive staining for topoisomerase II alpha, p27 kip1 , and p53, with positive staining in tumoral basaloid areas (22/30. Numerous tumors were focally positive with multiple markers, indicating a significant degree of variability in the complete group. Conclusions: Oncogenes, tumor suppressor genes, cell cycle regulators, and hormone receptors are variably expressed in sebaceomas. Our results suggest that in these tumors, selected marker staining seems to correlate

  19. High throughput functional genomics: identification of novel genes with tumor suppressor phenotypes.

    Science.gov (United States)

    Koenig-Hoffmann, Kerstin; Bonin-Debs, Angelika L; Boche, Irene; Gawin, Beate; Gnirke, Andrea; Hergersberg, Christoph; Madeo, Frank; Kazinski, Michael; Klein, Matthias; Korherr, Christian; Link, Dieter; Röhrig, Sascha; Schäfer, Rolf; Brinkmann, Ulrich

    2005-01-20

    We have used a combination of high throughput functional genomics, computerized database mining and expression analyses to discover novel human tumor suppressor genes (TSGs). A genome-wide high throughput cDNA phenotype screen was established to identify genes that induce apoptosis or reduce cell viability. TSGs are expressed in normal tissue and frequently act by reduction of growth of transformed cells or induce apoptosis. In agreement with that and thus serving as platform validation, our pro-apoptotic hits included genes for which tumor suppressing activities were known, such as kangai1 and CD81 antigen. Additional genes that so far have been claimed as putative TSGs or associated with tumor inhibitory activities (prostate differentiation factor, hRAS-like suppressor 3, DPH2L1-like and the metastasis inhibitor Kiss1) were confirmed in their proposed TSG-like phenotype by functionally defining their growth inhibitory or pro-apoptotic function towards cancer cells. Finally, novel genes were identified for which neither association with cell growth nor with apoptosis were previously described. A subset of these genes show characteristics of TSGs because they (i) reduce the growth or induce apoptosis in tumor cells; (ii) show reduced expression in tumor vs. normal tissue; and (iii) are located on chromosomal (LOH-) loci for which cancer-associated deletions are described. The pro-apoptotic phenotype and differential expression of these genes in normal and malignant tissue make them promising target candidates for the diagnosis and therapy of various tumors.

  20. SIRT3 interacts with the daf-16 homolog FOXO3a in the Mitochondria, as well as increases FOXO3a Dependent Gene expression

    Science.gov (United States)

    Jacobs, Kristi Muldoon; Pennington, J. Daniel; Bisht, Kheem S.; Aykin-Burns, Nukhet; Kim, Hyun-Seok; Mishra, Mark; Sun, Lunching; Nguyen, Phuongmai; Ahn, Bong-Hyun; Leclerc, Jaime; Deng, Chu-Xia; Spitz, Douglas R.; Gius, David

    2008-01-01

    Cellular longevity is a complex process relevant to age-related diseases including but not limited to chronic illness such as diabetes and metabolic syndromes. Two gene families have been shown to play a role in the genetic regulation of longevity; the Sirtuin and FOXO families. It is also established that nuclear Sirtuins interact with and under specific cellular conditions regulate the activity of FOXO gene family proteins. Thus, we hypothesize that a mitochondrial Sirtuin (SIRT3) might also interact with and regulate the activity of the FOXO proteins. To address this we used HCT116 cells overexpressing either wild-type or a catalytically inactive dominant negative SIRT3. For the first time we establish that FOXO3a is also a mitochondrial protein and forms a physical interaction with SIRT3 in mitochondria. Overexpression of a wild-type SIRT3 gene increase FOXO3a DNA-binding activity as well as FOXO3a dependent gene expression. Biochemical analysis of HCT116 cells over expressing the deacetylation mutant, as compared to wild-type SIRT3 gene, demonstrated an overall oxidized intracellular environment, as monitored by increase in intracellular superoxide and oxidized glutathione levels. As such, we propose that SIRT3 and FOXO3a comprise a potential mitochondrial signaling cascade response pathway. PMID:18781224

  1. Features and Usage Areas of MicroRNAs as Oncogenes and Tumor Suppressors

    Directory of Open Access Journals (Sweden)

    G. Seyda Seydel

    2009-02-01

    Full Text Available MicroRNAs (miRNA are small non-coding RNA of 19–24 nucleotides in length that were discovered 12 years ago by Victor Ambros and colleagues. They are important regulatory molecules in animals and plants. MicroRNAs are downregulate gene expression during various crucial cell processes such as apoptosis, differentiation and development. In addition, some miRNAs may function as oncogenes or tumor suppressors. More than 50% of miRNA genes are located in cancer-associated genomic regions or in fragile sites. Overexpressed miRNAs in cancers, such as mir17–92, may function as oncogenes and promote cancer development by negatively regulating tumor suppressor genes and genes that control cell differentiation or apoptosis. Underexpressed miRNAs in cancers, such as let–7, function as tumor suppressor genes and may inhibit cancers by regulating oncogenes and genes that control cell differentiation or apoptosis. miRNA expression profiles may become useful biomarkers for cancer diagnostics. [Archives Medical Review Journal 2009; 18(1.000: 1-12

  2. Arsenic exposure is associated with DNA hypermethylation of the tumor suppressor gene p16.

    Science.gov (United States)

    Lu, Guangming; Xu, Huiwen; Chang, De; Wu, Zhenglai; Yao, Xiaoyuan; Zhang, Shiying; Li, Zhenlong; Bai, Jieben; Cai, Qing; Zhang, Wen

    2014-01-01

    Occupational and environmental exposure to inorganic arsenic leads to development of cancer and represents a significant health hazard in more than 70 countries. The underlying mechanism for arsenic-induced carcinogenesis remains unclear. Laboratory studies suggest that arsenic is a poor mutagen but may cause epigenetic silencing of key tumor suppressor genes such as p16 through DNA hypermethylation. However, the evidence for an association between human arsenic exposure and abnormal DNA methylation of tumor suppressor genes is lacking. Paired case-control studies were conducted involving 40 individuals with high arsenic exposure and arsenicosis, 40 individuals with similarly high exposure to arsenic but without arsenicosis, and 40 individuals with normal exposure to arsenic. DNA methylation status of p16 was determined using methylation-specific PCR. Conditional logistic regression analysis showed that DNA hypermethylation of p16 gene was significantly associated with high arsenic exposure (Odds Ratio = 10.0, P = 0.0019) independently of the development of arsenicosis (Odds Ratio = 2.0, P = 0.1343). High exposure of arsenic in human is positively linked to DNA hypermethylation of p16 gene, suggesting that epigenetic silencing of key tumor suppressor may be an important mechanism by which arsenic promotes cancer initiation.

  3. KLF10, transforming growth factor-{beta}-inducible early gene 1, acts as a tumor suppressor

    Energy Technology Data Exchange (ETDEWEB)

    Song, Ki-Duk [Center for Agricultural Biomaterials, Seoul National University, Seoul 151-921 (Korea, Republic of); Laboratory of Protein Engineering and Comparative Immunology, School of Agricultural Biotechnology, Seoul National University, Seoul 151-921 (Korea, Republic of); Kim, Duk-Jung [The Institute of Hankook Life Science, 7-9 Myungryun-dong, Jongno-gu, Seoul 110-521 (Korea, Republic of); Lee, Jong Eun [Department of Anatomy, College of Medicine, Yonsei University, Seoul 120-752 (Korea, Republic of); Yun, Cheol-Heui [Center for Agricultural Biomaterials, Seoul National University, Seoul 151-921 (Korea, Republic of); Laboratory of Protein Engineering and Comparative Immunology, School of Agricultural Biotechnology, Seoul National University, Seoul 151-921 (Korea, Republic of); Lee, Woon Kyu, E-mail: wklee@inha.ac.kr [Laboratory of Developmental Genetics, School of Medicine, Inha University, Incheon 400-712 (Korea, Republic of); Brain Korea 21 Center for Advanced Medical Education, School of Medicine, Inha University, Incheon 400-712 (Korea, Republic of)

    2012-03-09

    Highlights: Black-Right-Pointing-Pointer KLF10{sup -/-} mice exhibited accelerated papilloma development after DMBA/TPA treatment. Black-Right-Pointing-Pointer KLF10{sup -/-} keratinocytes showed increased proliferation and apoptosis. Black-Right-Pointing-Pointer KLF10{sup -/-} MEFs yielded more colonies than wild-type one with H-Ras transfection. Black-Right-Pointing-Pointer KLF10 dose-dependently activated p21{sup WAF1/CIP1} transcription. Black-Right-Pointing-Pointer KLF10 is a tumor suppressor and that it targets p21{sup WAF1/CIP1} transcription. -- Abstract: Krueppel-like factor 10 (KLF10) has been suggested to be a putative tumor suppressor. In the present study, we generated KLF10 deficient mice to explore this hypothesis in vivo. KLF10 deficient mice exhibited increased predisposition to skin tumorigenesis and markedly accelerated papilloma development after DMBA/TPA treatment. On the other hand, KLF10 deficient keratinocytes showed increased proliferation and apoptosis. In colony formation assays after oncogenic H-Ras transfection, KLF10 deficient mouse embryonic fibroblasts (MEFs) yielded more colonies than wild-type MEFs. Furthermore, KLF10 dose-dependently activated p21{sup WAF1/CIP1} transcription, which was independent of p53 and Sp1 binding sites in p21{sup WAF1/CIP1} promoter. This study demonstrates that KLF10 is a tumor suppressor and that it targets p21{sup WAF1/CIP1} transcription.

  4. The molecular mechanisms that underlie the tumor suppressor function of LKB1

    Institute of Scientific and Technical Information of China (English)

    Dahua Fan; Chao Ma; Haitao Zhang

    2009-01-01

    Germline mutations of the LKB1 tumor suppressor gene result in Peutz-Jeghers syndrome (PJS) charac-terized by intestinal hamartomas and increased inci-dence of epithelial cancers. Inactivating mutations in LKB1 have also been found in certain sporadic human cancers and with particularly high frequency in lung cancer. LKB1 has now been demonstrated to play a crucial role in pulmonary tumorigenesis, controlling initiation, differentiation, and metastasis. Recent evi-dences showed that LKB1 is a multitasking kinase, with great potential in orchestrating cell activity. Thus far, LKB1 has been found to play a role in cell polarity, energy metabolism, apoptosis, cell cycle arrest, and cell proliferation, all of which may require the tumor sup-pressor function of this kinase and/or its catalytic activity. This review focuses on remarkable recent find-ings concerning the molecular mechanism by which the LKB1 protein kinase operates as a tumor suppressor and discusses the rational treatment strategies to indi-viduals suffering from PJS and other common dis-orders related to LKB1 signaling.

  5. SMG1 Acts as a Novel Potential Tumor Suppressor with Epigenetic Inactivation in Acute Myeloid Leukemia

    Directory of Open Access Journals (Sweden)

    Yahui Du

    2014-09-01

    Full Text Available Suppressor with morphogenetic effect on genitalia family member (SMG1 belongs to a family of phosphoinositide 3-kinase-related kinases and is the main kinase involved in nonsense-mediated mRNA decay. Recently, SMG1 was suggested as a novel potential tumor suppressor gene, particularly in hypoxic tumors. To investigate the function of SMG1 in acute myeloid leukemia (AML, we performed methylation-specific polymerase chain reaction and found that SMG1 was hypermethylated in the promoter region. SMG1 hypermethylation was found in 66% (33/50 of AML samples compared with none (0/14 of the normal controls. SMG1 mRNA was down-regulated in AML patients with hypermethylation status whereas it was readily expressed in patients without methylation. Moreover, treatment of AML cells with demethylating agent 5-aza-2'-deoxycytidine (decitabine inhibited AML cell growth and induced apoptosis by reversing SMG1 methylation status and restoring SMG1 expression. On the other hand, knockdown of SMG1 by RNA interference inhibited apoptosis. We also found that mTOR expression level was negatively correlated to SMG1 expression in AML patients which indicated that SMG1 and mTOR maybe act antagonistically to regulate AML cell growth. In conclusion, our results indicate that SMG1 acts as a potential tumor suppressor with epigenetic regulation in AML.

  6. Amplification of Mdmx (or Mdm4) directly contributes to tumor formation by inhibiting p53 tumor suppressor activity

    DEFF Research Database (Denmark)

    Danovi, Davide; Meulmeester, Erik; Pasini, Diego

    2004-01-01

    Human tumors are believed to harbor a disabled p53 tumor suppressor pathway, either through direct mutation of the p53 gene or through aberrant expression of proteins acting in the p53 pathway, such as p14(ARF) or Mdm2. A role for Mdmx (or Mdm4) as a key negative regulator of p53 function in vivo...... has been established. However, a direct contribution of Mdmx to tumor formation remains to be demonstrated. Here we show that retrovirus-mediated Mdmx overexpression allows primary mouse embryonic fibroblast immortalization and leads to neoplastic transformation in combination with HRas(V12......). Furthermore, the human Mdmx ortholog, Hdmx, was found to be overexpressed in a significant percentage of various human tumors and amplified in 5% of primary breast tumors, all of which retained wild-type p53. Hdmx was also amplified and highly expressed in MCF-7, a breast cancer cell line harboring wild...

  7. The tumor suppressor gene Trp53 protects the mouse lens against posterior subcapsular cataracts and the BMP receptor Acvr1 acts as a tumor suppressor in the lens

    Directory of Open Access Journals (Sweden)

    Luke A. Wiley

    2011-07-01

    We previously found that lenses lacking the Acvr1 gene, which encodes a bone morphogenetic protein (BMP receptor, had abnormal proliferation and cell death in epithelial and cortical fiber cells. We tested whether the tumor suppressor protein p53 (encoded by Trp53 affected this phenotype. Acvr1 conditional knockout (Acvr1CKO mouse fiber cells had increased numbers of nuclei that stained for p53 phosphorylated on serine 15, an indicator of p53 stabilization and activation. Deletion of Trp53 rescued the Acvr1CKO cell death phenotype in embryos and reduced Acvr1-dependent apoptosis in postnatal lenses. However, deletion of Trp53 alone increased the number of fiber cells that failed to withdraw from the cell cycle. Trp53CKO and Acvr1;Trp53DCKO (double conditional knockout, but not Acvr1CKO, lenses developed abnormal collections of cells at the posterior of the lens that resembled posterior subcapsular cataracts. Cells from human posterior subcapsular cataracts had morphological and molecular characteristics similar to the cells at the posterior of mouse lenses lacking Trp53. In Trp53CKO lenses, cells in the posterior plaques did not proliferate but, in Acvr1;Trp53DCKO lenses, many cells in the posterior plaques continued to proliferate, eventually forming vascularized tumor-like masses at the posterior of the lens. We conclude that p53 protects the lens against posterior subcapsular cataract formation by suppressing the proliferation of fiber cells and promoting the death of any fiber cells that enter the cell cycle. Acvr1 acts as a tumor suppressor in the lens. Enhancing p53 function in the lens could contribute to the prevention of steroid- and radiation-induced posterior subcapsular cataracts.

  8. Negative Regulation of Tumor Suppressor p53 by microRNA miR-504

    OpenAIRE

    2010-01-01

    Tumor suppressor p53 plays a central role in tumor prevention. p53 protein levels and activity are under a tight and complex regulation in cells to maintain the proper function of p53. microRNAs play a key role in the regulation of gene expression. Here we report the regulation of p53 through microRNA miR-504. miR-504 acts as a negative regulator of human p53 through its direct binding to two sites in p53 3′-UTR. Overexpression of miR-504 decreases p53 protein levels and functions in cells, i...

  9. Regulation of protein phosphatase 2A (PP2A) tumor suppressor function by PME-1.

    Science.gov (United States)

    Kaur, Amanpreet; Westermarck, Jukka

    2016-12-15

    Protein phosphatase 2A (PP2A) plays a major role in maintaining cellular signaling homeostasis by dephosphorylation of a variety of signaling proteins and acts as a tumor suppressor. Protein phosphatase methylesterase-1 (PME-1) negatively regulates PP2A activity by highly complex mechanisms that are reviewed here. Importantly, recent studies have shown that PME-1 promotes oncogenic MAPK/ERK and AKT pathway activities in various cancer types. In human glioma, high PME-1 expression correlates with tumor progression and kinase inhibitor resistance. We discuss the emerging cancer-associated function of PME-1 and its potential clinical relevance.

  10. Molecular Cloning of a Novel Bovine Homologue of the Drosophila Tumor Suppressor Gene, Lats

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Pervious studies demonstrate that lats, also known as warts, is a tumor suppressor gene in Drosophila[1,2]. Mutations of lats lead to an increase in cell number and organ size in Drosophila, indicating lats may be involved in organ size control. Furthermore, the high conservation of sequence and tumor suppression function of lats between Drosophila and human suggests that it may be also involved in organ size control of higher animals[3]. So here we isolated the bovine homologue of Drosophila lats. Sequence analysis indicates the bovine LATS1 to be very similar to other lats proteins.

  11. BOK displays cell death-independent tumor suppressor activity in non-small-cell lung carcinoma.

    Science.gov (United States)

    Moravcikova, Erika; Krepela, Evzen; Donnenberg, Vera S; Donnenberg, Albert D; Benkova, Kamila; Rabachini, Tatiana; Fernandez-Marrero, Yuniel; Bachmann, Daniel; Kaufmann, Thomas

    2017-11-15

    As the genomic region containing the Bcl-2-related ovarian killer (BOK) locus is frequently deleted in certain human cancers, BOK is hypothesized to have a tumor suppressor function. In the present study, we analyzed primary non-small-cell lung carcinoma (NSCLC) tumors and matched lung tissues from 102 surgically treated patients. We show that BOK protein levels are significantly downregulated in NSCLC tumors as compared to lung tissues (p < 0.001). In particular, we found BOK downregulation in NSCLC tumors of grades two (p = 0.004, n = 35) and three (p = 0.031, n = 39) as well as in tumors with metastases to hilar (pN1) (p = 0.047, n = 31) and mediastinal/subcarinal lymph nodes (pN2) (p = 0.021, n = 18) as opposed to grade one tumors (p = 0.688, n = 7) and tumors without lymph node metastases (p = 0.112, n = 51). Importantly, in lymph node-positive patients, BOK expression greater than the median value was associated with longer survival (p = 0.002, Mantel test). Using in vitro approaches, we provide evidence that BOK overexpression is inefficient in inducing apoptosis but that it inhibits TGFβ-induced migration and epithelial-to-mesenchymal transition (EMT) in lung adenocarcinoma-derived A549 cells. We have identified epigenetic mechanisms, in particular BOK promoter methylation, as an important means to silence BOK expression in NSCLC cells. Taken together, our data point toward a novel mechanism by which BOK acts as a tumor suppressor in NSCLC by inhibiting EMT. Consequently, the restoration of BOK levels in low-BOK-expressing tumors might favor the overall survival of NSCLC patients. © 2017 UICC.

  12. Insulin-FOXO3 signaling modulates circadian rhythms via regulation of clock transcription.

    Science.gov (United States)

    Chaves, Inês; van der Horst, Gijsbertus T J; Schellevis, Raymond; Nijman, Romana M; Koerkamp, Marian Groot; Holstege, Frank C P; Smidt, Marten P; Hoekman, Marco F M

    2014-06-02

    Circadian rhythms are responsive to external and internal cues, light and metabolism being among the most important. In mammals, the light signal is sensed by the retina and transmitted to the suprachiasmatic nucleus (SCN) master clock [1], where it is integrated into the molecular oscillator via regulation of clock gene transcription. The SCN synchronizes peripheral oscillators, an effect that can be overruled by incoming metabolic signals [2]. As a consequence, peripheral oscillators can be uncoupled from the master clock when light and metabolic signals are not in phase. The signaling pathways responsible for coupling metabolic cues to the molecular clock are being rapidly uncovered [3-5]. Here we show that insulin-phosphatidylinositol 3-kinase (PI3K)-Forkhead box class O3 (FOXO3) signaling is required for circadian rhythmicity in the liver via regulation of Clock. Knockdown of FoxO3 dampens circadian amplitude, an effect that is rescued by overexpression of Clock. Subsequently, we show binding of FOXO3 to two Daf-binding elements (DBEs) located in the Clock promoter area, implicating Clock as a transcriptional target of FOXO3. Transcriptional oscillation of both core clock and output genes in the liver of FOXO3-deficient mice is affected, indicating a disrupted hepatic circadian rhythmicity. Finally, we show that insulin, a major regulator of FOXO activity [6-9], regulates Clock levels in a PI3K- and FOXO3-dependent manner. Our data point to a key role of the insulin-FOXO3-Clock signaling pathway in the modulation of circadian rhythms.

  13. FOXO3-mTOR metabolic cooperation in the regulation of erythroid cell maturation and homeostasis.

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    Zhang, Xin; Campreciós, Genís; Rimmelé, Pauline; Liang, Raymond; Yalcin, Safak; Mungamuri, Sathish Kumar; Barminko, Jeffrey; D'Escamard, Valentina; Baron, Margaret H; Brugnara, Carlo; Papatsenko, Dmitri; Rivella, Stefano; Ghaffari, Saghi

    2014-10-01

    Ineffective erythropoiesis is observed in many erythroid disorders including β-thalassemia and anemia of chronic disease in which increased production of erythroblasts that fail to mature exacerbate the underlying anemias. As loss of the transcription factor FOXO3 results in erythroblast abnormalities similar to the ones observed in ineffective erythropoiesis, we investigated the underlying mechanisms of the defective Foxo3(-/-) erythroblast cell cycle and maturation. Here we show that loss of Foxo3 results in overactivation of the JAK2/AKT/mTOR signaling pathway in primary bone marrow erythroblasts partly mediated by redox modulation. We further show that hyperactivation of mTOR signaling interferes with cell cycle progression in Foxo3 mutant erythroblasts. Importantly, inhibition of mTOR signaling, in vivo or in vitro enhances significantly Foxo3 mutant erythroid cell maturation. Similarly, in vivo inhibition of mTOR remarkably improves erythroid cell maturation and anemia in a model of β-thalassemia. Finally we show that FOXO3 and mTOR are likely part of a larger metabolic network in erythroblasts as together they control the expression of an array of metabolic genes some of which are implicated in erythroid disorders. These combined findings indicate that a metabolism-mediated regulatory network centered by FOXO3 and mTOR control the balanced production and maturation of erythroid cells. They also highlight physiological interactions between these proteins in regulating erythroblast energy. Our results indicate that alteration in the function of this network might be implicated in the pathogenesis of ineffective erythropoiesis.

  14. FOXO3 modulates endothelial gene expression and function by classical and alternative mechanisms.

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    Czymai, Tobias; Viemann, Dorothee; Sticht, Carsten; Molema, Grietje; Goebeler, Matthias; Schmidt, Marc

    2010-04-02

    FOXO transcription factors represent targets of the phosphatidylinositol 3-kinase/protein kinase B survival pathway controlling important biological processes, such as cell cycle progression, apoptosis, vascular remodeling, stress responses, and metabolism. Recent studies suggested the existence of alternative mechanisms of FOXO-dependent gene expression beyond classical binding to a FOXO-responsive DNA-binding element (FRE). Here we analyzed the relative contribution of those mechanisms to vascular function by comparing the transcriptional and cellular responses to conditional activation of FOXO3 and a corresponding FRE-binding mutant in human primary endothelial cells. We demonstrate that FOXO3 controls expression of vascular remodeling genes in an FRE-dependent manner. In contrast, FOXO3-induced cell cycle arrest and apoptosis occurs independently of FRE binding, albeit FRE-dependent gene expression augments the proapoptotic response. These findings are supported by bioinformatical analysis, which revealed a statistical overrepresentation of cell cycle regulators and apoptosis-related genes in the group of co-regulated genes. Molecular analysis of FOXO3-induced endothelial apoptosis excluded modulators of the extrinsic death receptor pathway and demonstrated important roles for the BCL-2 family members BIM and NOXA in this process. Although NOXA essentially contributed to FRE-dependent apoptosis, BIM was effectively induced in the absence of FRE-binding, and small interfering RNA-mediated BIM depletion could rescue apoptosis induced by both FOXO3 mutants. These data suggest BIM as a critical cell type-specific mediator of FOXO3-induced endothelial apoptosis, whereas NOXA functions as an amplifying factor. Our study provides the first comprehensive analysis of alternatively regulated FOXO3 targets in relevant primary cells and underscores the importance of such genes for endothelial function and integrity.

  15. A tumor suppressor role of the Bub3 spindle checkpoint protein after apoptosis inhibition

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    Moutinho-Santos, Tatiana

    2013-01-01

    Most solid tumors contain aneuploid cells, indicating that the mitotic checkpoint is permissive to the proliferation of chromosomally aberrant cells. However, mutated or altered expression of mitotic checkpoint genes accounts for a minor proportion of human tumors. We describe a Drosophila melanogaster tumorigenesis model derived from knocking down spindle assembly checkpoint (SAC) genes and preventing apoptosis in wing imaginal discs. Bub3-deficient tumors that were also deficient in apoptosis displayed neoplastic growth, chromosomal aneuploidy, and high proliferative potential after transplantation into adult flies. Inducing aneuploidy by knocking down CENP-E and preventing apoptosis does not induce tumorigenesis, indicating that aneuploidy is not sufficient for hyperplasia. In this system, the aneuploidy caused by a deficient SAC is not driving tumorigenesis because preventing Bub3 from binding to the kinetochore does not cause hyperproliferation. Our data suggest that Bub3 has a nonkinetochore-dependent function that is consistent with its role as a tumor suppressor. PMID:23609535

  16. Tumor suppressor function of Betaig-H3 gene in radiation carcinogenesis

    Science.gov (United States)

    Zhao, Y. L.; Piao, C. Q.; Hei, T. K.

    Interaction between cell and extracellular matrix (ECM) plays a crucial role in tumor invasiveness and metastasis. Using an immortalized human bronchial epithelial (BEP2D) cell model, we showed previously that expression of a list of genes including Betaig-h3 (induced by transforming growth factor-β) DCC (deleted in colorectal cancer), p21 cip1, c-fos , Heat shock protein (HSP27) and cytokeratin 14 were differentially expressed in several independently generated, radiation-induced tumor cell lines (TL1-TL5) relative to parental BEP2D cells. Our previous data further demonstrated that loss of tumor suppressor gene(s) as a likely mechanism of radiation carcinogenesis. In the present study, we chose Betaig-h3 and DCC that were downregulated in tumorigenic cells for further study. Restored expression of Betaig-h3 gene, not DCC gene, by transfecting cDNA into tumor cells resulted in a significant reduction in tumor growth. While integrin receptor α5β1 was overexpressed in tumor cells, its expression was corrected to the level found in control BEP2D cells after Betaig-h3 transfection. These data suggest that Betaig-h3 gene is involved in tumor progression by regulating integrin α5β1 receptor. Furthermore, exogenous TGF-β1 induced expression of Betaig-h3 gene and inhibited the growth of both control and tumorigenic BEP2D cells. Therefore, downregulation of Betaig-h3 gene may results from the decreased expression of upstream mediators such as TGF-β. The findings provide strong evidence that the Betaig-h3 gene has tumor suppressor function in radiation-induced tumorigenic human bronchial epithelial cells and suggest a potential target for interventional therapy.

  17. FoxO3 coordinates metabolic pathways to maintain redox balance in neural stem cells.

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    Yeo, Hyeonju; Lyssiotis, Costas A; Zhang, Yuqing; Ying, Haoqiang; Asara, John M; Cantley, Lewis C; Paik, Ji-Hye

    2013-10-02

    Forkhead Box O (FoxO) transcription factors act in adult stem cells to preserve their regenerative potential. Previously, we reported that FoxO maintains the long-term proliferative capacity of neural stem/progenitor cells (NPCs), and that this occurs, in part, through the maintenance of redox homeostasis. Herein, we demonstrate that among the FoxO3-regulated genes in NPCs are a host of enzymes in central carbon metabolism that act to combat reactive oxygen species (ROS) by directing the flow of glucose and glutamine carbon into defined metabolic pathways. Characterization of the metabolic circuit observed upon loss of FoxO3 revealed a drop in glutaminolysis and filling of the tricarboxylic acid (TCA) cycle. Additionally, we found that glucose uptake, glucose metabolism and oxidative pentose phosphate pathway activity were similarly repressed in the absence of FoxO3. Finally, we demonstrate that impaired glucose and glutamine metabolism compromises the proliferative potential of NPCs and that this is exacerbated following FoxO3 loss. Collectively, our findings show that a FoxO3-dependent metabolic programme supports redox balance and the neurogenic potential of NPCs.

  18. The candidate tumor suppressor gene ECRG4 inhibits cancer cells migration and invasion in esophageal carcinoma

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    Lu ShihHsin

    2010-10-01

    Full Text Available Abstract Background The esophageal cancer related gene 4 (ECRG4 was initially identified and cloned in our laboratory from human normal esophageal epithelium (GenBank accession no.AF325503. ECRG4 was a new tumor suppressor gene in esophageal squamous cell carcinoma (ESCC associated with prognosis. In this study, we investigated the novel tumor-suppressing function of ECRG4 in cancer cell migration, invasion, adhesion and cell cycle regulation in ESCC. Methods Transwell and Boyden chamber experiments were utilized to examined the effects of ECRG4 expression on ESCC cells migration, invasion and adhesion. And flow cytometric analysis was used to observe the impact of ECRG4 expression on cell cycle regulation. Finally, the expression levels of cell cycle regulating proteins p53 and p21 in human ESCC cells transfected with ECRG4 gene were evaluated by Western blotting. Results The restoration of ECRG4 expression in ESCC cells inhibited cancer cells migration and invasion (P P > 0.05. Furthermore, ECRG4 could cause cell cycle G1 phase arrest in ESCC (P Conclusion ECRG4 is a candidate tumor suppressor gene which suppressed tumor cells migration and invasion without affecting cell adhesion ability in ESCC. Furthermore, ECRG4 might cause cell cycle G1 phase block possibly through inducing the increased expression of p53 and p21 proteins in ESCC.

  19. Mutation analysis of novel human liver-related putative tumor suppressor gene in hepatocellular carcinoma

    Institute of Scientific and Technical Information of China (English)

    Cheng Liao; Tsai-Ping Li; Mu-Jun Zhao; Jing Zhao; Hai Song; Pascal Pineau; Agnès Marchio; Anne Dejean; Pierre Tiollais; Hong-Yang Wang

    2003-01-01

    AIM: To find the point mutations meaningful for inactivationof liver-related putative tumor suppressor gene (LPTS) gene,a human novel liver-related putative tumor suppressor geneand telomerase inhibitor in hepatocellular carcinoma.METHODS: The entire coding sequence of LPTS genewas examined for mutations by single strand conformationpolymorphism (SSCP) assay and PCR products directsequencing in 56 liver cancer cell lines, 7 ovarian cancerand 7 head & neck tumor cell lines and 70 pairs of HCCtissues samples. The cDNA fragment coding for the mostfrequent mutant protein was subcloned into GST fusionexpression vector. The product was expressed in E. coliand purified by glutathione-agarose column. Telomericrepeat amplification protocol (TRAP) assays wereperformed to study the effect of point mutation totelomerase inhibitory activity.RESULTS: SSCP gels showed the abnormal shifting bandsand DNA sequencing found that there were 5 differentmutations and/or polymorphisms in 12 tumor cell lineslocated at exon2, exon5 and exon7. The main alterationswere A(778)A/G and A(880)T in exon7. The change in siteof 778 could not be found in HCC tissue samples, while themutation in position 880 was seen in 7 (10 %) cases. Themutation in the site of 880 had no effect on telomeraseinhibitory activity.CONCLUSION: Alterations identified in this study arepolymorphisms of LPTS gene. LPTS mutations occur in HCCbut are infrequent and of little effect on the telomeraseinhibitory function of the protein. Epigenetics, such asmethylation, acetylation, may play the key role in inactivationof LPTS.

  20. High mutability of the tumor suppressor genes RASSF1 and RBSP3 (CTDSPL in cancer.

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    Vladimir I Kashuba

    Full Text Available BACKGROUND: Many different genetic alterations are observed in cancer cells. Individual cancer genes display point mutations such as base changes, insertions and deletions that initiate and promote cancer growth and spread. Somatic hypermutation is a powerful mechanism for generation of different mutations. It was shown previously that somatic hypermutability of proto-oncogenes can induce development of lymphomas. METHODOLOGY/PRINCIPAL FINDINGS: We found an exceptionally high incidence of single-base mutations in the tumor suppressor genes RASSF1 and RBSP3 (CTDSPL both located in 3p21.3 regions, LUCA and AP20 respectively. These regions contain clusters of tumor suppressor genes involved in multiple cancer types such as lung, kidney, breast, cervical, head and neck, nasopharyngeal, prostate and other carcinomas. Altogether in 144 sequenced RASSF1A clones (exons 1-2, 129 mutations were detected (mutation frequency, MF = 0.23 per 100 bp and in 98 clones of exons 3-5 we found 146 mutations (MF = 0.29. In 85 sequenced RBSP3 clones, 89 mutations were found (MF = 0.10. The mutations were not cytidine-specific, as would be expected from alterations generated by AID/APOBEC family enzymes, and appeared de novo during cell proliferation. They diminished the ability of corresponding transgenes to suppress cell and tumor growth implying a loss of function. These high levels of somatic mutations were found both in cancer biopsies and cancer cell lines. CONCLUSIONS/SIGNIFICANCE: This is the first report of high frequencies of somatic mutations in RASSF1 and RBSP3 in different cancers suggesting it may underlay the mutator phenotype of cancer. Somatic hypermutations in tumor suppressor genes involved in major human malignancies offer a novel insight in cancer development, progression and spread.

  1. Salinomycin decreases doxorubicin resistance in hepatocellular carcinoma cells by inhibiting the β-catenin/TCF complex association via FOXO3a activation

    Science.gov (United States)

    Chen, Wei; Zhi, Xiao; Feng, Xinhua; Bai, Xueli; Liang, Tingbo

    2015-01-01

    Doxorubicin is a conventional and effective chemotherapy drug against hepatocellular carcinoma (HCC). However, during long-term doxorubicin monotherapy, HCC cells may eventually develop acquired-resistance to doxorubicin which results in recurrence and a poor prognosis. Salinomycin, an ionophore antibiotic, was recently reported to selectively kill human cancer stem cells (CSCs) which were response for chemoresistance. In this study, salinomycin was found to exert synergistic cytotoxicity with doxorubicin in HCC cells and be capable of inhibiting doxorubicin-induced epithelial-mesenchymal transition (EMT), an important cellular process involved in the acquired chemoresistance of tumors. Further experiments revealed that FOXO3a, a multifunctional transcription factor that can be activated by salinomycin, was vital in mediating doxorubicin-induced EMT. In addition, activated FOXO3a disturbed the interaction between β-catenin and TCF and inhibited the expression of β-catenin/TCF target genes (ZEB1, c-Myc and CyclinD1), which played important roles in doxorubicin-induced EMT in HCC cells. Finally, the enhanced curative efficacy of combination treatment of doxorubicin and salinomycin for HCC was confirmed in established xenograft models. In summary, the present study identifies a new doxorubicin-based chemotherapy for advanced HCC and provides a potential anti-cancer strategy targeting FOXO3a and related cell pathway molecules. PMID:25871400

  2. Salinomycin decreases doxorubicin resistance in hepatocellular carcinoma cells by inhibiting the β-catenin/TCF complex association via FOXO3a activation.

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    Zhou, Yue; Liang, Chao; Xue, Fei; Chen, Wei; Zhi, Xiao; Feng, Xinhua; Bai, Xueli; Liang, Tingbo

    2015-04-30

    Doxorubicin is a conventional and effective chemotherapy drug against hepatocellular carcinoma (HCC). However, during long-term doxorubicin monotherapy, HCC cells may eventually develop acquired-resistance to doxorubicin which results in recurrence and a poor prognosis. Salinomycin, an ionophore antibiotic, was recently reported to selectively kill human cancer stem cells (CSCs) which were response for chemoresistance. In this study, salinomycin was found to exert synergistic cytotoxicity with doxorubicin in HCC cells and be capable of inhibiting doxorubicin-induced epithelial-mesenchymal transition (EMT), an important cellular process involved in the acquired chemoresistance of tumors. Further experiments revealed that FOXO3a, a multifunctional transcription factor that can be activated by salinomycin, was vital in mediating doxorubicin-induced EMT. In addition, activated FOXO3a disturbed the interaction between β-catenin and TCF and inhibited the expression of β-catenin/TCF target genes (ZEB1, c-Myc and CyclinD1), which played important roles in doxorubicin-induced EMT in HCC cells. Finally, the enhanced curative efficacy of combination treatment of doxorubicin and salinomycin for HCC was confirmed in established xenograft models. In summary, the present study identifies a new doxorubicin-based chemotherapy for advanced HCC and provides a potential anti-cancer strategy targeting FOXO3a and related cell pathway molecules.

  3. The Regulation and Function of miR-21-FOXO3a-miR-34b/c Signaling in Breast Cancer

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    Xiangyan Liu

    2015-01-01

    Full Text Available Upregulation of miR-21 (microRNA-21 and downregulation of miR-34b/c have been found in breast cancer (BC. However, their regulation mechanism and function roles in BC have not been fully addressed. Here, we report that miR-21 levels were inversely correlated with miR-34b/c levels in BC. MiR-21 upregulation contributes to PTEN downregulation, which is beneficial for the activation of PI3K/AKT signaling. The activation of AKT phosphorylates FOXO3a, triggering relocalization of FOXO3a proteins from the nucleus to the cytoplasm. FOXO3a is a newly identified transcription factor responsible for miR-34b/c expression. Downregulation of nuclear FOXO3a decreased the expression levels of miR-34b and miR-34c in breast cancer cells, in which p53 was mutated. We also found upregulation of circulating miR-21 and downregulation of circulating miR-34b/c in BC patients’ serum. More importantly, we showed that systemic delivery of miR-34b/c or with anti-miR-21 significantly inhibited breast tumor growth in vivo. These results suggest that high circulating levels of miR-21 and low levels of miR-34b/c may provide potential biomarkers for BC diagnosis, and systemic delivery of miR-34b/c has potential as a therapeutic option for BC treatment.

  4. HDAC2 selectively regulates FOXO3a-mediated gene transcription during oxidative stress-induced neuronal cell death.

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    Peng, Shengyi; Zhao, Siqi; Yan, Feng; Cheng, Jinbo; Huang, Li; Chen, Hong; Liu, Qingsong; Ji, Xunming; Yuan, Zengqiang

    2015-01-21

    All neurodegenerative diseases are associated with oxidative stress-induced neuronal death. Forkhead box O3a (FOXO3a) is a key transcription factor involved in neuronal apoptosis. However, how FOXO3a forms complexes and functions in oxidative stress processing remains largely unknown. In the present study, we show that histone deacetylase 2 (HDAC2) forms a physical complex with FOXO3a, which plays an important role in FOXO3a-dependent gene transcription and oxidative stress-induced mouse cerebellar granule neuron (CGN) apoptosis. Interestingly, we also found that HDAC2 became selectively enriched in the promoter region of the p21 gene, but not those of other target genes, and inhibited FOXO3a-mediated p21 transcription. Furthermore, we found that oxidative stress reduced the interaction between FOXO3a and HDAC2, leading to an increased histone H4K16 acetylation level in the p21 promoter region and upregulated p21 expression in a manner independent of p53 or E2F1. Phosphorylation of HDAC2 at Ser 394 is important for the HDAC2-FOXO3a interaction, and we found that cerebral ischemia/reperfusion reduced phosphorylation of HDAC2 at Ser 394 and mitigated the HDAC2-FOXO3a interaction in mouse brain tissue. Our study reveals the novel regulation of FOXO3a-mediated selective gene transcription via epigenetic modification in the process of oxidative stress-induced cell death, which could be exploited therapeutically.

  5. FOXO3 Shares Common Targets with ASCL1 Genome-wide and Inhibits ASCL1-Dependent Neurogenesis

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    Ashley E. Webb

    2013-08-01

    Full Text Available FOXO transcription factors are central regulators of longevity from worms to humans. FOXO3, the FOXO isoform associated with exceptional human longevity, preserves adult neural stem cell pools. Here, we identify FOXO3 direct targets genome-wide in primary cultures of adult neural progenitor cells (NPCs. Interestingly, FOXO3-bound sites are enriched for motifs for bHLH transcription factors, and FOXO3 shares common targets with the proneuronal bHLH transcription factor ASCL1/MASH1 in NPCs. Analysis of the chromatin landscape reveals that FOXO3 and ASCL1 are particularly enriched at the enhancers of genes involved in neurogenic pathways. Intriguingly, FOXO3 inhibits ASCL1-dependent neurogenesis in NPCs and direct neuronal conversion in fibroblasts. FOXO3 also restrains neurogenesis in vivo. Our study identifies a genome-wide interaction between the prolongevity transcription factor FOXO3 and the cell-fate determinant ASCL1 and raises the possibility that FOXO3’s ability to restrain ASCL1-dependent neurogenesis may help preserve the neural stem cell pool.

  6. Paracrine Apoptotic Effect of p53 Mediated by Tumor Suppressor Par-4

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    Ravshan Burikhanov

    2014-01-01

    Full Text Available The guardian of the genome, p53, is often mutated in cancer and may contribute to therapeutic resistance. Given that p53 is intact and functional in normal tissues, we harnessed its potential to inhibit the growth of p53-deficient cancer cells. Specific activation of p53 in normal fibroblasts selectively induced apoptosis in p53-deficient cancer cells. This paracrine effect was mediated by p53-dependent secretion of the tumor suppressor Par-4. Accordingly, the activation of p53 in normal mice, but not p53−/− or Par-4−/− mice, caused systemic elevation of Par-4, which induced apoptosis of p53-deficient tumor cells. Mechanistically, p53 induced Par-4 secretion by suppressing the expression of its binding partner, UACA, which sequesters Par-4. Thus, normal cells can be empowered by p53 activation to induce Par-4 secretion for the inhibition of therapy-resistant tumors.

  7. A CRISPR/Cas9 Functional Screen Identifies Rare Tumor Suppressors

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    Katigbak, Alexandra; Cencic, Regina; Robert, Francis; Sénécha, Patrick; Scuoppo, Claudio; Pelletier, Jerry

    2016-01-01

    An enormous amount of tumor sequencing data has been generated through large scale sequencing efforts. The functional consequences of the majority of mutations identified by such projects remain an open, unexplored question. This problem is particularly complicated in the case of rare mutations where frequency of occurrence alone or prediction of functional consequences are insufficient to distinguish driver from passenger or bystander mutations. We combine genome editing technology with a powerful mouse cancer model to uncover previously unsuspected rare oncogenic mutations in Burkitt’s lymphoma. We identify two candidate tumor suppressors whose loss cooperate with MYC over-expression to accelerate lymphomagenesis. Our results highlight the utility of in vivo CRISPR/Cas9 screens combined with powerful mouse models to identify and validate rare oncogenic modifier events from tumor mutational data. PMID:27982060

  8. MicroRNA-542-5p as a novel tumor suppressor in neuroblastoma.

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    Bray, Isabella; Tivnan, Amanda; Bryan, Kenneth; Foley, Niamh H; Watters, Karen M; Tracey, Lorraine; Davidoff, Andrew M; Stallings, Raymond L

    2011-04-01

    Several studies have implicated the dysregulation of microRNAs in neuroblastoma pathogenesis, an often fatal paediatric cancer arising from precursor cells of the sympathetic nervous system. Our group and others have demonstrated that lower expression of miR-542-5p is highly associated with poor patient survival, indicating a potential tumor suppressive function. Here, we demonstrate that ectopic over-expression of this miRNA decreases the invasive potential of neuroblastoma cell lines in vitro, along with primary tumor growth and metastases in an orthotopic mouse xenograft model, providing the first functional evidence for the involvement of miR-542-5p as a tumor suppressor in any type of cancer.

  9. Tumor suppressor protein SMAR1 modulates the roughness of cell surface: combined AFM and SEM study

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    Mamgain Hitesh

    2009-10-01

    Full Text Available Abstract Background Imaging tools such as scanning electron microscope (SEM and atomic force microscope (AFM can be used to produce high-resolution topographic images of biomedical specimens and hence are well suited for imaging alterations in cell morphology. We have studied the correlation of SMAR1 expression with cell surface smoothness in cell lines as well as in different grades of human breast cancer and mouse tumor sections. Methods We validated knockdown and overexpression of SMAR1 using RT-PCR as well as Western blotting in human embryonic kidney (HEK 293, human breast cancer (MCF-7 and mouse melanoma (B16F1 cell lines. The samples were then processed for cell surface roughness studies using atomic force microscopy (AFM and scanning electron microscopy (SEM. The same samples were used for microarray analysis as well. Tumors sections from control and SMAR1 treated mice as well as tissues sections from different grades of human breast cancer on poly L-lysine coated slides were used for AFM and SEM studies. Results Tumor sections from mice injected with melanoma cells showed pronounced surface roughness. In contrast, tumor sections obtained from nude mice that were first injected with melanoma cells followed by repeated injections of SMAR1-P44 peptide, exhibited relatively smoother surface profile. Interestingly, human breast cancer tissue sections that showed reduced SMAR1 expression exhibited increased surface roughness compared to the adjacent normal breast tissue. Our AFM data establishes that treatment of cells with SMAR1-P44 results into increase in cytoskeletal volume that is supported by comparative gene expression data showing an increase in the expression of specific cytoskeletal proteins compared to the control cells. Altogether, these findings indicate that tumor suppressor function of SMAR1 might be exhibited through smoothening of cell surface by regulating expression of cell surface proteins. Conclusion Tumor suppressor

  10. Tumor suppressor ARF regulates tissue microenvironment and tumor growth through modulation of macrophage polarization.

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    Jiménez-García, Lidia; Herranz, Sandra; Higueras, María Angeles; Luque, Alfonso; Hortelano, Sonsoles

    2016-10-11

    Tumor microenvironment has been described to play a key role in tumor growth, progression, and metastasis. Macrophages are a major cellular constituent of the tumor stroma, and particularly tumor associated macrophages (TAMs or M2-like macrophages) exert important immunosuppressive activity and a pro-tumoral role within the tumor microenvironment. Alternative-reading frame (ARF) gene is widely inactivated in human cancer. We have previously demonstrated that ARF deficiency severely impairs inflammatory response establishing a new role for ARF in the regulation of innate immunity. On the basis of these observations, we hypothesized that ARF may also regulates tumor growth through recruitment and modulation of the macrophage phenotype in the tumor microenvironment. Xenograft assays of B16F10 melanoma cells into ARF-deficient mice resulted in increased tumor growth compared to those implanted in WT control mice. Tumors from ARF-deficient mice exhibited significantly increased number of TAMs as well as microvascular density. Transwell assays showed crosstalk between tumor cells and macrophages. On the one hand, ARF-deficient macrophages modulate migratory ability of the tumor cells. And on the other, tumor cells promote the skewing of ARF-/- macrophages toward a M2-type polarization. In conclusion, these results demonstrate that ARF deficiency facilitates the infiltration of macrophages into the tumor mass and favors their polarization towards a M2 phenotype, thus promoting tumor angiogenesis and tumor growth. This work provides novel information about the critical role of ARF in the modulation of tumor microenvironment.

  11. Zebrafish foxo3b negatively regulates canonical Wnt signaling to affect early embryogenesis.

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    Xun-wei Xie

    Full Text Available FOXO genes are involved in many aspects of development and vascular homeostasis by regulating cell apoptosis, proliferation, and the control of oxidative stress. In addition, FOXO genes have been showed to inhibit Wnt/β-catenin signaling by competing with T cell factor to bind to β-catenin. However, how important of this inhibition in vivo, particularly in embryogenesis is still unknown. To demonstrate the roles of FOXO genes in embryogenesis will help us to further understand their relevant physiological functions. Zebrafish foxo3b gene, an orthologue of mammalian FOXO3, was expressed maternally and distributed ubiquitously during early embryogenesis and later restricted to brain. After morpholino-mediated knockdown of foxo3b, the zebrafish embryos exhibited defects in axis and neuroectoderm formation, suggesting its critical role in early embryogenesis. The embryo-developmental marker gene staining at different stages, phenotype analysis and rescue assays revealed that foxo3b acted its role through negatively regulating both maternal and zygotic Wnt/β-catenin signaling. Moreover, we found that foxo3b could interact with zebrafish β-catenin1 and β-catenin2 to suppress their transactivation in vitro and in vivo, further confirming its role relevant to the inhibition of Wnt/β-catenin signaling. Taken together, we revealed that foxo3b played a very important role in embryogenesis and negatively regulated maternal and zygotic Wnt/β-catenin signaling by directly interacting with both β-catenin1 and β-catenin2. Our studies provide an in vivo model for illustrating function of FOXO transcription factors in embryogenesis.

  12. Isoform-specific interactions of the von Hippel-Lindau tumor suppressor protein

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    Minervini, Giovanni; Mazzotta, Gabriella M.; Masiero, Alessandro; Sartori, Elena; Corrà, Samantha; Potenza, Emilio; Costa, Rodolfo; Tosatto, Silvio C. E.

    2015-01-01

    Deregulation of the von Hippel-Lindau tumor suppressor protein (pVHL) is considered one of the main causes for malignant renal clear-cell carcinoma (ccRCC) insurgence. In human, pVHL exists in two isoforms, pVHL19 and pVHL30 respectively, displaying comparable tumor suppressor abilities. Mutations of the p53 tumor suppressor gene have been also correlated with ccRCC insurgence and ineffectiveness of treatment. A recent proteomic analysis linked full length pVHL30 with p53 pathway regulation through complex formation with the p14ARF oncosuppressor. The alternatively spliced pVHL19, missing the first 53 residues, lacks this interaction and suggests an asymmetric function of the two pVHL isoforms. Here, we present an integrative bioinformatics and experimental characterization of the pVHL oncosuppressor isoforms. Predictions of the pVHL30 N-terminus three-dimensional structure suggest that it may exist as an ensemble of structured and disordered forms. The results were used to guide Yeast two hybrid experiments to highlight isoform-specific binding properties. We observed that the physical pVHL/p14ARF interaction is specifically mediated by the 53 residue long pVHL30 N-terminal region, suggesting that this N-terminus acts as a further pVHL interaction interface. Of note, we also observed that the shorter pVHL19 isoform shows an unexpected high tendency to form homodimers, suggesting an additional isoform-specific binding specialization. PMID:26211615

  13. Effect of sulfur dioxide on expression of proto-oncogenes and tumor suppressor genes from rats.

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    Bai, Juli; Meng, Ziqiang

    2010-06-01

    Sulfur dioxide (SO(2)) is a ubiquitous air pollutant that is present in low concentrations in the urban air, and in higher concentrations in the working environment. In the present study, male Wistar rats were housed in exposure chambers and treated with 14.00 +/- 1.01, 28.00 +/- 1.77 and 56.00 +/- 3.44 mg m(-3) SO(2) for 6 h/day for 7 days, while control group was exposed to filtered air in the same condition. The mRNA and protein levels of proto-oncogenes (c-fos, c-jun, c-myc, and Ki-ras) and tumor suppressor genes (p53, Rb, and p16) were analyzed in lungs using a real-time reverse transcription-polymerase chain reaction (real-time RT-PCR) assay and Western blot analysis. The results showed that mRNA and protein levels of c-fos, c-jun, c-myc, Ki-ras, and p53 in lungs were increased in a dose-dependent manner, while mRNA and protein levels of Rb and p16 were decreased in lungs of rats after SO(2) inhalation. These results lead to a conclusion that SO(2) exposure could activate expressions of proto-oncogenes and suppress expressions of tumor suppressor genes, which might relate to the molecular mechanism of cocarcinogenic properties and potential carcinogenic effects of SO(2). According to previous studies, the results also indicated that promoter genes of apoptosis and tumor suppressor genes could produce apoptotic signals to antagonize the growth signals that arise from oncogenes. Understanding its molecular controls will benefit development of treatments for many diseases.

  14. The Regulation of Tumor Suppressor p63 by the Ubiquitin-Proteasome System

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    Stephen R. Armstrong

    2016-12-01

    Full Text Available The protein p63 has been identified as a homolog of the tumor suppressor protein p53 and is capable of inducing apoptosis, cell cycle arrest, or senescence. p63 has at least six isoforms, which can be divided into two major groups: the TAp63 variants that contain the N-terminal transactivation domain and the ΔNp63 variants that lack the N-terminal transactivation domain. The TAp63 variants are generally considered to be tumor suppressors involved in activating apoptosis and suppressing metastasis. ΔNp63 variants cannot induce apoptosis but can act as dominant negative inhibitors to block the function of TAp53, TAp73, and TAp63. p63 is rarely mutated in human tumors and is predominately regulated at the post-translational level by phosphorylation and ubiquitination. This review focuses primarily on regulation of p63 by the ubiquitin E-3 ligase family of enzymes via ubiquitination and proteasome-mediated degradation, and introduces a new key regulator of the p63 protein.

  15. Lysine methylation-dependent binding of 53BP1 to the pRb tumor suppressor.

    Science.gov (United States)

    Carr, Simon M; Munro, Shonagh; Zalmas, Lykourgos-Panagiotis; Fedorov, Oleg; Johansson, Catrine; Krojer, Tobias; Sagum, Cari A; Bedford, Mark T; Oppermann, Udo; La Thangue, Nicholas B

    2014-08-01

    The retinoblastoma tumor suppressor protein pRb is a key regulator of cell cycle progression and mediator of the DNA damage response. Lysine methylation at K810, which occurs within a critical Cdk phosphorylation motif, holds pRb in the hypophosphorylated growth-suppressing state. We show here that methyl K810 is read by the tandem tudor domain containing tumor protein p53 binding protein 1 (53BP1). Structural elucidation of 53BP1 in complex with a methylated K810 pRb peptide emphasized the role of the 53BP1 tandem tudor domain in recognition of the methylated lysine and surrounding residues. Significantly, binding of 53BP1 to methyl K810 occurs on E2 promoter binding factor target genes and allows pRb activity to be effectively integrated with the DNA damage response. Our results widen the repertoire of cellular targets for 53BP1 and suggest a previously unidentified role for 53BP1 in regulating pRb tumor suppressor activity.

  16. Genetic and Epigenetic Alterations of DLC-1, a Candidate Tumor Suppressor Gene, in Nasopharyngeal Carcinoma

    Institute of Scientific and Technical Information of China (English)

    Dan PENG; Cai-Ping REN; Hong-Mei YI; Liang ZHOU; Xu-Yu YANG; Hui LI; Kai-Tai YAO

    2006-01-01

    The DLC-1 gene, located at the human chromosome region 8p22, behaves like a tumor suppressor gene and is frequently deleted in diverse tumors. The deletion of 8p22 is not an uncommon event in nasopharyngeal carcinoma (NPC), therefore we explored the expression levels of the DLC-1 gene in NPCs and NPC cell lines by reverse transcription-polymerase chain reaction. The results showed the mRNA level of DLC-1 was downregulated. To identify the mechanism of DLC-1 downregulation in NPC, we investigated the methylation status of the DLC-1 gene using methylation-specific PCR, and found that 79% (31 of 39) of the NPC tissues and two DLC-1 nonexpressing NPC cell lines, 6-10B and 5-8F, were methylated in the DLC-1 CpG island. Microsatellite PCR was also carried out, and loss of heterozygosity was found at four microsatellite sites (D8S552, D8S1754, D8S1790 and D8S549) covering the whole DLC-1 gene with ratios of 33% (4 of 12 informative cases), 18% (2 of 11), 5% (1 of 18), and 25% (3 of 12), respectively. Taken together, our results suggest that DLC-1 might be an NPC-related tumor suppressor gene affected by aberrant promoter methylation and gene deletion.

  17. Dnmt3b is a haploinsufficient tumor suppressor gene in Myc-induced lymphomagenesis.

    Science.gov (United States)

    Vasanthakumar, Aparna; Lepore, Janet B; Zegarek, Matthew H; Kocherginsky, Masha; Singh, Mahi; Davis, Elizabeth M; Link, Petra A; Anastasi, John; Le Beau, Michelle M; Karpf, Adam R; Godley, Lucy A

    2013-03-14

    The drivers of abnormal DNA methylation in human cancers include widespread aberrant splicing of the DNMT3B gene, producing abnormal transcripts that encode truncated proteins that may act as dominant negative isoforms. To test whether reduced Dnmt3b dosage can alter tumorigenesis, we bred Dnmt3b(+/-) mice to Eµ-Myc mice, a mouse model susceptible to B-cell lymphomas. Eµ-Myc/Dnmt3b(+/-) mice showed a dramatic acceleration of lymphomagenesis, greater even than that observed in Eµ-Myc mice that express a truncated DNMT3B isoform found in human tumors, DNMT3B7. This finding indicates that Dnmt3b can act as a haploinsufficient tumor suppressor gene. Although reduction in both Dnmt3b dosage and expression of DNMT3B7 within the Eµ-Myc system had similar effects on tumorigenesis and DNA hypermethylation, different molecular mechanisms appear to underlie these changes. This study offers insight into how de novo DNA methyltransferases function as tumor suppressors and the sensitivity of Myc-induced lymphomas to DNA methylation.

  18. SERS-based nanobiosensing for ultrasensitive detection of the p53 tumor suppressor

    Directory of Open Access Journals (Sweden)

    Domenici F

    2011-09-01

    Full Text Available Fabio Domenici, Anna Rita Bizzarri, Salvatore Cannistraro Biophysics and Nanoscience Centre, Faculty of Science, Università della Tuscia, Viterbo, Italy Background: One of the main challenges in biomedicine is improvement of detection sensitivity to achieve tumor marker recognition at a very low concentration when the disease is not significantly advanced. A pivotal role in cancer defense is played by the p53 tumor suppressor, therefore its detection with high sensitivity may contribute considerably to early diagnosis of cancer. In this work, we present a new analytical method based on surface-enhanced Raman spectroscopy which could significantly increase the sensitivity of traditional bioaffinity techniques. p53 molecules were anchored to gold nanoparticles by means of the bifunctional linker 4-aminothiophenol (4-ATP. The characteristic vibrational bands of the p53-4-ATP nanoparticle system were then used to identify the p53 molecules when they were captured by a recognition substrate comprising a monolayer of azurin in molecules possessing significant affinity for this tumor suppressor. The Raman signal enhancement achieved by 4-ATP-mediated crosslinking of p53 to 50 nm gold nanoparticles enabled detect of this protein at a concentration down to 5 × 10-13 M. Keywords: surface-enhanced Raman spectroscopy, p53, ultrasensitive detection, atomic force microscopy

  19. Neuron-Specific Deletion of the Nf2 Tumor Suppressor Impairs Functional Nerve Regeneration

    Science.gov (United States)

    Schulz, Alexander; Büttner, Robert; Toledo, Andrea; Baader, Stephan L.; von Maltzahn, Julia; Irintchev, Andrey; Bauer, Reinhard; Morrison, Helen

    2016-01-01

    In contrast to axons of the central nervous system (CNS), axons of the peripheral nervous system (PNS) show better, but still incomplete and often slow regeneration following injury. The tumor suppressor protein merlin, mutated in the hereditary tumor syndrome Neurofibromatosis type 2 (NF2), has recently been shown to have RhoA regulatory functions in PNS neurons—in addition to its well-characterized, growth-inhibitory activity in Schwann cells. Here we report that the conditional knockout of merlin in PNS neurons leads to impaired functional recovery of mice following sciatic nerve crush injury, in a gene-dosage dependent manner. Gross anatomical or electrophysiological alterations of sciatic nerves could not be detected. However, correlating with attenuated RhoA activation due to merlin deletion, ultrastructural analysis of nerve samples indicated enhanced sprouting of axons with reduced caliber size and increased myelination compared to wildtype animals. We conclude that deletion of the tumor suppressor merlin in the neuronal compartment of peripheral nerves results in compromised functional regeneration after injury. This mechanism could explain the clinical observation that NF2 patients suffer from higher incidences of slowly recovering facial nerve paralysis after vestibular schwannoma surgery. PMID:27467574

  20. Phenotype diversity in familial cylindromatosis: a frameshift mutation in the tumor suppressor gene CYLD underlies different tumors of skin appendages.

    Science.gov (United States)

    Poblete Gutiérrez, Pamela; Eggermann, Thomas; Höller, Daniela; Jugert, Frank K; Beermann, Torsten; Grussendorf-Conen, Elke-Ingrid; Zerres, Klaus; Merk, Hans F; Frank, Jorge

    2002-08-01

    Familial cylindromatosis (turban tumor syndrome; Brooke-Spiegler syndrome) (OMIM numbers 123850, 132700, 313100, and 605041) is a rare autosomal dominantly inherited tumor syndrome. The disorder can present with cutaneous adnexal tumors such as cylindromas, trichoepitheliomas, and spiradenomas, and tumors preferably develop in hairy areas of the body such as head and neck. In affected families, mutations have been demonstrated in the CYLD gene located on chromosome 16q12-13 and reveal the characteristic attributes of a tumor suppressor. Here, we studied familial cylindromatosis in a multigeneration family of German origin. Clinically, some individuals only revealed discrete small skin-colored tumors localized in the nasolabial region whereas one family member showed expansion of multiple big tumors on the trunk and in a turban-like fashion on the scalp. Histologically, cylindromas as well as epithelioma adenoides cysticum were found. We detected a frameshift mutation in the CYLD gene, designated 2253delG, underlying the disorder and were able to show that a single mutation can result in distinct clinical and histologic expression in familial cylindromatosis. The reasons for different expression patterns of the same genetic defect in this disease remain elusive, however. Identification of mutations in the CYLD gene enable us to rapidly confirm putative diagnoses on the genetic level and to provide affected families with genetic counseling.

  1. SUMOylation of the ING1b tumor suppressor regulates gene transcription

    DEFF Research Database (Denmark)

    Satpathy, Shankha; Guérillon, Claire; Kim, Tae-Sun;

    2014-01-01

    The INhibitor of Growth (ING) proteins are encoded as multiple isoforms in five ING genes (ING1 -5) and act as type II tumor suppressors. They are growth inhibitory when overexpressed and are frequently mislocalized or downregulated in several forms of cancer. ING1 and ING2 are stoichiometric mem......1b E195A), we further demonstrate that ING1b SUMOylation regulates the binding of ING1b to the ISG15 and DGCR8 promoters, consequently regulating ISG15 and DGCR8 transcription. These results suggest a role for ING1b SUMOylation in the regulation of gene transcription....

  2. Regulation of transcription functions of the p53 tumor suppressor by the mdm-2 oncogene.

    OpenAIRE

    1995-01-01

    BACKGROUND: Mdm-2, a zinc finger protein, negatively regulates the p53 tumor suppressor gene product by binding to it and preventing transcriptional activation (16). MATERIALS AND METHODS: Assays for p53 mediated transcription, repression and activation by mutant and wild-type p53 proteins were used to measure the ability of mdm-2 to block each activity. RESULTS: Mdm-2 was able to inhibit all three functions of the wild-type and mutant p53 activities; transcriptional activation by the wild-ty...

  3. Double-Stranded-RNA-Activated Protein Kinase PKR Enhances Transcriptional Activation by Tumor Suppressor p53

    OpenAIRE

    1999-01-01

    The tumor suppressor p53 plays a key role in inducing G1 arrest and apoptosis following DNA damage. The double-stranded-RNA-activated protein PKR is a serine/threonine interferon (IFN)-inducible kinase which plays an important role in regulation of gene expression at both transcriptional and translational levels. Since a cross talk between IFN-inducible proteins and p53 had already been established, we investigated whether and how p53 function was modulated by PKR. We analyzed p53 function in...

  4. The Regulatory Mechanisms of Tumor Suppressor P16INK4A and Relevance to Cancer†

    OpenAIRE

    Li, Junan; Poi, Ming Jye; Tsai, Ming-Daw

    2011-01-01

    P16INK4A (also known as P16 and MTS1), a protein consisting exclusively of four ankyrin repeats, is recognized as a tumor suppressor mainly due to the prevalence of genetic inactivation of the p16INK4A (or CDKN2A) gene in virtually all types of human cancers. However, it has also been shown that elevated expression (up-regulation) of P16 is involved in cellular senescence, aging, and cancer progression, indicating that the regulation of P16 is critical for its function. Here, we discuss the r...

  5. Nfkb1 is a haploinsufficient DNA damage-specific tumor suppressor

    OpenAIRE

    Voce, David J; Schmitt, Adam M.; Uppal, Abhineet; McNerney, Megan E.; Bernal, Giovanna M; Cahill, Kirk E.; Wahlstrom, Joshua S.; Nassiri, Ashley; Yu, Xiaohong; Crawley, Clayton D.; White, Kevin P.; Onel, Kenan; Weichselbaum, Ralph R.; Yamini, Bakhtiar

    2014-01-01

    NF-κB proteins play a central and subunit-specific role in the response to DNA damage. Previous work identified p50/NF-κB1 as being necessary for cytotoxicity in response to DNA alkylation damage. Given the importance of damage-induced cell death for maintenance of genomic stability, we examined whether Nfkb1 acts as a tumor suppressor in the setting of alkylation damage. Hprt mutation analysis demonstrates that Nfkb1−/− cells accumulate more alkylator-induced, but not ionizing radiation (IR)...

  6. Inhibitor of differentiation 4 (Id4 is a potential tumor suppressor in prostate cancer

    Directory of Open Access Journals (Sweden)

    Carey Jason PW

    2009-06-01

    Full Text Available Abstract Background Inhibitor of differentiation 4 (Id4, a member of the Id gene family is also a dominant negative regulator of basic helix loop helix (bHLH transcription factors. Some of the functions of Id4 appear to be unique as compared to its other family members Id1, Id2 and Id3. Loss of Id4 gene expression in many cancers in association with promoter hypermethylation has led to the proposal that Id4 may act as a tumor suppressor. In this study we provide functional evidence that Id4 indeed acts as a tumor suppressor and is part of a cancer associated epigenetic re-programming. Methods Data mining was used to demonstrate Id4 expression in prostate cancer. Methylation specific polymerase chain reaction (MSP analysis was performed to understand molecular mechanisms associated with Id4 expression in prostate cancer cell lines. The effect of ectopic Id4 expression in DU145 cells was determined by cell cycle analysis (3H thymidine incorporation and FACS, expression of androgen receptor, p53 and cyclin dependent kinase inhibitors p27 and p21 by a combination of RT-PCR, real time-PCR, western blot and immuno-cytochemical analysis. Results Id4 expression was down-regulated in prostate cancer. Id4 expression was also down-regulated in prostate cancer line DU145 due to promoter hyper-methylation. Ectopic Id4 expression in DU145 prostate cancer cell line led to increased apoptosis and decreased cell proliferation due in part by an S-phase arrest. In addition to S-phase arrest, ectopic Id4 expression in PC3 cells also resulted in prolonged G2/M phase. At the molecular level these changes were associated with increased androgen receptor (AR, p21, p27 and p53 expression in DU145 cells. Conclusion The results suggest that Id4 acts directly as a tumor suppressor by influencing a hierarchy of cellular processes at multiple levels that leads to a decreased cell proliferation and change in morphology that is possibly mediated through induction of previously

  7. Cancer-associated p53 tetramerization domain mutants: quantitative analysis reveals a low threshold for tumor suppressor inactivation

    Energy Technology Data Exchange (ETDEWEB)

    Kamada, R.; Anderson, C.; Nomura, T.; Sakaguchi, K.

    2011-01-07

    The tumor suppressor p53, a 393-amino acid transcription factor, induces cell cycle arrest and apoptosis in response to genotoxic stress. Its inactivation via the mutation of its gene is a key step in tumor progression, and tetramer formation is critical for p53 post-translational modification and its ability to activate or repress the transcription of target genes vital in inhibiting tumor growth. About 50% of human tumors have TP53 gene mutations; most are missense ones that presumably lower the tumor suppressor activity of p53. In this study, we explored the effects of known tumor-derived missense mutations on the stability and oligomeric structure of p53; our comprehensive, quantitative analyses encompassed the tetramerization domain peptides representing 49 such substitutions in humans. Their effects on tetrameric structure were broad, and the stability of the mutant peptides varied widely ({Delta}T{sub m} = 4.8 {approx} -46.8 C). Because formation of a tetrameric structure is critical for protein-protein interactions, DNA binding, and the post-translational modification of p53, a small destabilization of the tetrameric structure could result in dysfunction of tumor suppressor activity. We suggest that the threshold for loss of tumor suppressor activity in terms of the disruption of the tetrameric structure of p53 could be extremely low. However, other properties of the tetramerization domain, such as electrostatic surface potential and its ability to bind partner proteins, also may be important.

  8. Discovery of Prostate Cancer Tumor Suppressors and Mediators of MDV3100 Resistance Through in Vivo RNA Interference Screen

    Science.gov (United States)

    2015-11-01

    AWARD NUMBER: W81XWH-13-1-0084 TITLE: Discovery of Prostate Cancer Tumor Suppressors and Mediators of MDV3100 Resistance through in Vivo...Suppressors and Mediators of MDV3100 Resistance through in Vivo RNA Interference Screen 5b. GRANT NUMBER W81XWH-13-1-0084 5c. PROGRAM ELEMENT NUMBER 6...Public Release; Distribution Unlimited 13. SUPPLEMENTARY NOTES 14. ABSTRACT We set out to identify factors that mediate resistance to enzalutamide

  9. NDRG2 is a candidate tumor-suppressor for oral squamous-cell carcinoma

    Energy Technology Data Exchange (ETDEWEB)

    Furuta, Hiroshi; Kondo, Yuudai [Division of Oral and Maxillofacial Surgery, Medicine of Sensory and Motor Organs, University of Miyazaki, 5200 Kihara, Kiyotake, Miyazaki-gun, Miyazaki 889-1692 (Japan); Division of Tumor and Cellular Biochemistry, Department of Medical Sciences, Faculty of Medicine, University of Miyazaki, 5200 Kihara, Kiyotake, Miyazaki-gun, Miyazaki 889-1692 (Japan); Nakahata, Shingo; Hamasaki, Makoto [Division of Tumor and Cellular Biochemistry, Department of Medical Sciences, Faculty of Medicine, University of Miyazaki, 5200 Kihara, Kiyotake, Miyazaki-gun, Miyazaki 889-1692 (Japan); Sakoda, Sumio [Division of Oral and Maxillofacial Surgery, Medicine of Sensory and Motor Organs, University of Miyazaki, 5200 Kihara, Kiyotake, Miyazaki-gun, Miyazaki 889-1692 (Japan); Morishita, Kazuhiro, E-mail: kmorishi@med.miyazaki-u.ac.jp [Division of Tumor and Cellular Biochemistry, Department of Medical Sciences, Faculty of Medicine, University of Miyazaki, 5200 Kihara, Kiyotake, Miyazaki-gun, Miyazaki 889-1692 (Japan)

    2010-01-22

    Oral cancer is one of the most common cancers worldwide, and squamous-cell carcinoma (OSCC) is the most common phenotype of oral cancer. Although patients with OSCC have poor survival rates and a high incidence of metastasis, the molecular mechanisms of OSCC development have not yet been elucidated. This study investigated whether N-myc downstream-regulated gene 2 (NDRG2) contributes to the carcinogenesis of OSCC, as NDRG2 is reported to be a candidate tumor-suppressor gene in a wide variety of cancers. The down-regulation of NDRG2 mRNA, which was dependent on promoter methylation, was seen in the majority of OSCC cases and in several cases of precancerous leukoplakia with dysplasia. Induction of NDRG2 expression in an HSC-3/OSCC cell line significantly inhibited cell proliferation and decreased colony formation ability on soft agar. The majority of OSCC cell lines showed an activation of PI3K/Akt signaling, and enforced expression of NDRG2 in HSC-3 cells decreased the level of phosphorylated Akt at Serine 473 (p-Akt). Immunohistochemical p-Akt staining was detected in 56.5% of the OSCC tumors, and 80.4% of the tumors were negative for NDRG2 staining. Moreover, positive p-Akt staining was inversely correlated with decreased NDRG2 expression in OSCC tumors with moderate to poor differentiation (p < 0.005). Therefore, NDRG2 is a candidate tumor-suppressor gene for OSCC development and probably contributes to the tumorigenesis of OSCC partly via the modulation of Akt signaling.

  10. Snail transcription factor negatively regulates maspin tumor suppressor in human prostate cancer cells

    Directory of Open Access Journals (Sweden)

    Neal Corey L

    2012-08-01

    Full Text Available Abstract Background Maspin, a putative tumor suppressor that is down-regulated in breast and prostate cancer, has been associated with decreased cell motility. Snail transcription factor is a zinc finger protein that is increased in breast cancer and is associated with increased tumor motility and invasion by induction of epithelial-mesenchymal transition (EMT. We investigated the molecular mechanisms by which Snail increases tumor motility and invasion utilizing prostate cancer cells. Methods Expression levels were analyzed by RT-PCR and western blot analyses. Cell motility and invasion assays were performed, while Snail regulation and binding to maspin promoter was analyzed by luciferase reporter and chromatin immunoprecipitation (ChIP assays. Results Snail protein expression was higher in different prostate cancer cells lines as compared to normal prostate epithelial cells, which correlated inversely with maspin expression. Snail overexpression in 22Rv1 prostate cancer cells inhibited maspin expression and led to increased migration and invasion. Knockdown of Snail in DU145 and C4-2 cancer cells resulted in up-regulation of maspin expression, concomitant with decreased migration. Transfection of Snail into 22Rv1 or LNCaP cells inhibited maspin promoter activity, while stable knockdown of Snail in C4-2 cells increased promoter activity. ChIP analysis showed that Snail is recruited to the maspin promoter in 22Rv1 cells. Conclusions Overall, this is the first report showing that Snail can negatively regulate maspin expression by directly repressing maspin promoter activity, leading to increased cell migration and invasion. Therefore, therapeutic targeting of Snail may be useful to re-induce expression of maspin tumor suppressor and prevent prostate cancer tumor progression.

  11. The FOXO3A rs2802292 G-Allele Associates with Improved Peripheral and Hepatic Insulin Sensitivity and Increased Skeletal Muscle-FOXO3A mRNA Expression in Twins

    DEFF Research Database (Denmark)

    Banasik, Karina; Ribel-Madsen, Rasmus; Gjesing, Anette P;

    2011-01-01

    Objective: The minor G-allele of FOXO3A rs2802292 has been associated with longevity. We aimed to investigate whether a phenotype related to healthy metabolic aging could be identified in individuals carrying the longevity-associated FOXO3A rs2802292 G-allele. Research Design and Methods: rs2802292...

  12. Split End Family RNA Binding Proteins: Novel Tumor Suppressors Coupling Transcriptional Regulation with RNA Processing

    Directory of Open Access Journals (Sweden)

    Hairui Su

    2015-01-01

    Full Text Available Split End (SPEN family proteins have three members: SPEN, RBM15, and RBM15B. SPEN family proteins contain three conserved RNA recognition motifs on the N-terminal region and an SPOC domain on the C-terminal region. RBM15 is fused to MKL1 in chromosome translocation t (1;22, which causes childhood acute megakaryoblastic leukemia (AMKL. Haploinsufficiency of RBM15 in AMKL indicates that RBM15 is a tumor suppressor. Both SPEN and RBM15 are mutated in a variety of cancer types, implying that they are tumor suppressors. SPEN and RBM15are required for the development of multiple organs including hematopoiesis partly via regulating the NOTCH signaling pathway, as well as the WNT signaling pathway in species ranging from Drosophila to mammals. Besides transcriptional regulation, RBM15 regulates RNA export and RNA splicing. In this review, we summarized data in the literature on how the members in SPEN family regulate gene expression at transcription and RNA processing steps. The crosstalk between epigenetic regulation and RNA metabolism is increasingly appreciated in understanding tumorigenesis. Studying the SPEN family of RNA binding proteins will create new perspectives for cancer therapy.

  13. Cancer-associated splicing variant of tumor suppressor AIMP2/p38: pathological implication in tumorigenesis.

    Directory of Open Access Journals (Sweden)

    Jin Woo Choi

    2011-03-01

    Full Text Available Although ARS-interacting multifunctional protein 2 (AIMP2, also named as MSC p38 was first found as a component for a macromolecular tRNA synthetase complex, it was recently discovered to dissociate from the complex and work as a potent tumor suppressor. Upon DNA damage, AIMP2 promotes apoptosis through the protective interaction with p53. However, it was not demonstrated whether AIMP2 was indeed pathologically linked to human cancer. In this work, we found that a splicing variant of AIMP2 lacking exon 2 (AIMP2-DX2 is highly expressed by alternative splicing in human lung cancer cells and patient's tissues. AIMP2-DX2 compromised pro-apoptotic activity of normal AIMP2 through the competitive binding to p53. The cells with higher level of AIMP2-DX2 showed higher propensity to form anchorage-independent colonies and increased resistance to cell death. Mice constitutively expressing this variant showed increased susceptibility to carcinogen-induced lung tumorigenesis. The expression ratio of AIMP2-DX2 to normal AIMP2 was increased according to lung cancer stage and showed a positive correlation with the survival of patients. Thus, this work identified an oncogenic splicing variant of a tumor suppressor, AIMP2/p38, and suggests its potential for anti-cancer target.

  14. Tumor Suppressor Genes within Common Fragile Sites Are Active Players in the DNA Damage Response.

    Directory of Open Access Journals (Sweden)

    Idit Hazan

    2016-12-01

    Full Text Available The role of common fragile sites (CFSs in cancer remains controversial. Two main views dominate the discussion: one suggests that CFS loci are hotspots of genomic instability leading to inactivation of genes encoded within them, while the other view proposes that CFSs are functional units and that loss of the encoded genes confers selective pressure, leading to cancer development. The latter view is supported by emerging evidence showing that expression of a given CFS is associated with genome integrity and that inactivation of CFS-resident tumor suppressor genes leads to dysregulation of the DNA damage response (DDR and increased genomic instability. These two viewpoints of CFS function are not mutually exclusive but rather coexist; when breaks at CFSs are not repaired accurately, this can lead to deletions by which cells acquire growth advantage because of loss of tumor suppressor activities. Here, we review recent advances linking some CFS gene products with the DDR, genomic instability, and carcinogenesis and discuss how their inactivation might represent a selective advantage for cancer cells.

  15. Tumor Suppressor RARRES1 Regulates DLG2, PP2A, VCP, EB1, and Ankrd26

    Directory of Open Access Journals (Sweden)

    Ziad J. Sahab, Michael D. Hall, Lihua Zhang, Amrita K. Cheema, Stephen W. Byers

    2010-01-01

    Full Text Available Retinoic Acid Receptor Responder (RARRES1 initially identified as a novel retinoic acid receptor regulated gene in the skin is a putative tumor suppressor of unknown function. RARRES1 was knocked down in immortalized human prostatic epithelial cell line PWR-1E cells and differential protein expression was identified using differential in-gel electrophoresis (DIGE followed by matrix-assisted laser desorption ionization (MALDI mass spectrometry and western Blot analysis excluding highly abundant proteins routinely identified in almost all proteomics projects. Knock-down of RARRES1: 1- down-regulates PP2A, an enzyme involved in the negative regulation of the growth hormone-stimulated signal transduction pathways; 2- down-regulates Valosin-containing protein causing impaired autophagy; 3- up-regulates the tumor suppressor disks large 2; 4- up-regulates Ankrd26 that belongs to the POTE family of genes that are highly expressed in cancer patients with poor outcome; and 5- down-regulates EB1, a protein that is involved in spindle dynamics and chromosome alignment during mitosis.

  16. Newcomers to the WW Domain-Mediated Network of the Hippo Tumor Suppressor Pathway.

    Science.gov (United States)

    Sudol, Marius

    2010-11-01

    The Hippo tumor suppressor pathway regulates the size of organs by controlling 2 opposing processes: proliferation and apoptosis. The pathway was originally defined in Drosophila, but it is well conserved in mammals. One of the unique features of Hippo signaling is the unusually wide occurrence of WW domains and its cognate PPxY ligand motifs within components of this pathway. Recently, it was proposed that the prevalence of WW domain-mediated complexes in the Hippo signaling pathway should facilitate its molecular analysis and help in the identification of new components of the Hippo-centered network. Indeed, several new members of the Hippo pathway, which form functional complexes with WW domains of YAP and TAZ effectors, were recently described. We focus here on 2 families of such proteins, angiomotins and SMADs, plus 1 regulatory factor, WBP-2, which together shed new light on the rapidly expanding Hippo network. Since the Hippo pathway acts as a tumor suppressor pathway, the complexes described here, which assemble on WW domains of YAP and TAZ, represent potential targets of cancer therapy.

  17. The tumor suppressor Rb and its related Rbl2 genes are regulated by Utx histone demethylase

    Energy Technology Data Exchange (ETDEWEB)

    Terashima, Minoru; Ishimura, Akihiko; Yoshida, Masakazu [Division of Functional Genomics, Cancer Research Institute, Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Ishikawa (Japan); Suzuki, Yutaka; Sugano, Sumio [Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa 277-8561, Chiba (Japan); Suzuki, Takeshi, E-mail: suzuki-t@staff.kanazawa-u.ac.jp [Division of Functional Genomics, Cancer Research Institute, Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Ishikawa (Japan)

    2010-08-20

    Research highlights: {yields} Utx increases expression of Rb and Rbl2 genes through its demethylase activity. {yields} Utx changes histone H3 methylation on the Rb and Rbl2 promoters. {yields} Utx induces decreased cell proliferation of mammalian primary cells. -- Abstract: Utx is a candidate tumor suppressor gene that encodes histone H3 lysine 27 (H3K27) demethylase. In this study, we found that ectopic expression of Utx enhanced the expression of retinoblastoma tumor suppressor gene Rb and its related gene Rbl2. This activation was dependent on the demethylase activity of Utx, and was suggested to contribute to the decreased cell proliferation induced by Utx. A chromatin immunoprecipitation assay showed that over-expressed Utx was associated with the promoter regions of Rb and Rbl2 resulting in the removal of repressive H3K27 tri-methylation and the increase in active H3K4 tri-methylation. Furthermore, siRNA-mediated knockdown of Utx revealed the recruitment of endogenous Utx protein on the promoters of Rb and Rbl2 genes. These results indicate that Rb and Rbl2 are downstream target genes of Utx and may play important roles in Utx-mediated cell growth control.

  18. TSGene 2.0: an updated literature-based knowledgebase for tumor suppressor genes.

    Science.gov (United States)

    Zhao, Min; Kim, Pora; Mitra, Ramkrishna; Zhao, Junfei; Zhao, Zhongming

    2016-01-01

    Tumor suppressor genes (TSGs) are a major type of gatekeeper genes in the cell growth. A knowledgebase with the systematic collection and curation of TSGs in multiple cancer types is critically important for further studying their biological functions as well as for developing therapeutic strategies. Since its development in 2012, the Tumor Suppressor Gene database (TSGene), has become a popular resource in the cancer research community. Here, we reported the TSGene version 2.0, which has substantial updates of contents (e.g. up-to-date literature and pan-cancer genomic data collection and curation), data types (noncoding RNAs and protein-coding genes) and content accessibility. Specifically, the current TSGene 2.0 contains 1217 human TSGs (1018 protein-coding and 199 non-coding genes) curated from over 9000 articles. Additionally, TSGene 2.0 provides thousands of expression and mutation patterns derived from pan-cancer data of The Cancer Genome Atlas. A new web interface is available at http://bioinfo.mc.vanderbilt.edu/TSGene/. Systematic analyses of 199 non-coding TSGs provide numerous cancer-specific non-coding mutational events for further screening and clinical use. Intriguingly, we identified 49 protein-coding TSGs that were consistently down-regulated in 11 cancer types. In summary, TSGene 2.0, which is the only available database for TSGs, provides the most updated TSGs and their features in pan-cancer.

  19. PRDM1/BLIMP1: a tumor suppressor gene in B and T cell lymphomas.

    Science.gov (United States)

    Boi, Michela; Zucca, Emanuele; Inghirami, Giorgio; Bertoni, Francesco

    2015-05-01

    The gene encoding the human BLIMP1, prdm1, is located on chromosome 6q21, a locus frequently deleted in lymphoid tumors. BLIMP1 is able to silence its target genes in a context-dependent manner through different mechanisms. BLIMP1 is expressed in both B and T cells, in which it plays important functions. In B cells, BLIMP1 acts as the master regulator of plasma cell differentiation, repressed by BCL6 and repressing both BCL6 and PAX5. In T cells, BLIMP1 is a critical factor for most terminal effector cell differentiation in both CD4+ and CD8+ T cells. BLIMP1 is frequently inactivated in a variety of lymphomas, including diffuse large B cell lymphomas, Natural Killer cell lymphoma and anaplastic large T cell lymphoma. In this review, we will summarize the role of BLIMP1 in normal cells, focusing on lymphoid cells, and on its function as tumor suppressor gene in lymphomas.

  20. Tumor suppressor gene E-cadherin and its role in normal and malignant cells

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    Pećina-Šlaus Nives

    2003-10-01

    Full Text Available Abstract E-cadherin tumor suppressor genes are particularly active area of research in development and tumorigenesis. The calcium-dependent interactions among E-cadherin molecules are critical for the formation and maintenance of adherent junctions in areas of epithelial cell-cell contact. Loss of E-cadherin-mediated-adhesion characterises the transition from benign lesions to invasive, metastatic cancer. Nevertheless, there is evidence that E-cadherins may also play a role in the wnt signal transduction pathway, together with other key molecules involved in it, such as beta-catenins and adenomatous poliposis coli gene products. The structure and function of E-cadherin, gene and protein, in normal as well as in tumor cells are reviewed in this paper.

  1. Frameshift mutation of UVRAG: Switching a tumor suppressor to an oncogene in colorectal cancer.

    Science.gov (United States)

    He, Shanshan; Liang, Chengyu

    2015-01-01

    Colorectal cancer (CRC) ranks as the second leading cause of cancer-related deaths in the Western world. It has a nearly 50% metastasis rate and only a subset of patients respond to current treatment strategy. UVRAG, a key autophagy effector and a guardian of chromosomal stability, is truncated by a frameshift (FS) mutation in CRC with microsatellite instability (MSI). However, the pathological and clinical significance of this UVRAG truncation remains less understood. Our recent study discovered that this FS mutation yields a much shortened form of the UVRAG protein, which counteracts most of the tumor-suppressor functions of wild-type (WT) UVRAG in autophagy, centrosome stability, and DNA repair in a dominant-negative fashion. Whereas this truncated mutation of UVRAG promotes tumorigenesis, epithelial-to-mesenchymal transition, and metastasis, it appears to sensitize CRC tumors to adjuvant chemotherapy, making it a potential molecular marker to individualize therapeutic approach in CRC.

  2. MFSD2A is a novel lung tumor suppressor gene modulating cell cycle and matrix attachment

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    Shames David S

    2010-03-01

    Full Text Available Abstract Background MFSD2A (major facilitator superfamily domain containing 2 gene maps on chromosome 1p34 within a linkage disequilibrium block containing genetic elements associated with progression of lung cancer. Results Here we show that MFSD2A expression is strongly downregulated in non-small cell lung cancer cell lines of different histotypes and in primary lung adenocarcinomas. Experimental modulation of MFSD2A in lung cancer cells is associated with alteration of mRNA levels of genes involved in cell cycle control and interaction with the extracellular matrix. Exogenous expression of MFSD2A in lung cancer cells induced a G1 block, impaired adhesion and migration in vitro, and significantly reduced tumor colony number in vitro (4- to 27-fold, P in vivo (~3-fold, P Conclusion Together these data suggest that MFSD2A is a novel lung cancer tumor suppressor gene that regulates cell cycle progression and matrix attachment.

  3. Tricyclic Guanidine Alkaloids from the Marine Sponge Acanthella cavernosa that Stabilize the Tumor Suppressor PDCD4

    Science.gov (United States)

    Grkovic, Tanja; Blees, Johanna S.; Bayer, Magdalena M.; Colburn, Nancy H.; Thomas, Cheryl L.; Henrich, Curtis J.; Peach, Megan L.; McMahon, James B.; Schmid, Tobias; Gustafson, Kirk R.

    2014-01-01

    A cell-based high-throughput screen that assessed the cellular stability of a tumor suppressor protein PDCD4 (Programmed cell death 4) was used to identify a new guanidine-containing marine alkaloid mirabilin K (3), as well as the known compounds mirabilin G (1) and netamine M (2). The structures of these tricyclic guanidine alkaloids were established from extensive spectroscopic analyses. Compounds 1 and 2 inhibited cellular degradation of PDCD4 with EC50 values of 1.8 μg/mL and 2.8 μg/mL, respectively. Mirabilin G (1) and netamine M (2) are the first marine natural products reported to stabilize PDCD4 under tumor promoting conditions. PMID:25196934

  4. LATS1 tumor suppressor is a novel actin-binding protein and negative regulator of actin polymerization

    Institute of Scientific and Technical Information of China (English)

    Stacy Visser-Grieve; Zhonghua Zhou; Yi-Min She; He Huang; Terry D Cyr; Tian Xu; Xiaolong Yang

    2011-01-01

    Dear Editor,The LATS tumor suppressor,conserved from Drosophila (dlats) to humans (LATS1,LATS2),plays a vital role in maintaining cellular homeostasis in humans since loss of either LATS1 or LATS2 leads to the development of numerous cancer types such as breast cancer and leukemia [1].Apart from its roles as a Ser/Thr kinase within the emerging Hippo pathway regulating cell proliferation and apoptosis,ultimately leading to the control of organ size and tumorigenesis [2],LATS is also implicated in a broad range of functions including regulation of genetic stability,transcription,and protein stability [1 ].Recently,tumor suppressors have also been shown to affect the later stages of tumorigenesis,including metastasis.Among this group of metastasis regulators are genes that can directly affect actin dynamics by binding to F-actin,such as the tumor suppressors p53 [3],NF2 [4] and APC [5].

  5. Autophagy induction by leptin contributes to suppression of apoptosis in cancer cells and xenograft model: involvement of p53/FoxO3A axis.

    Science.gov (United States)

    Nepal, Saroj; Kim, Mi Jin; Hong, Jin Tae; Kim, Sang Hyun; Sohn, Dong-Hwan; Lee, Sung Hee; Song, Kyung; Choi, Dong Young; Lee, Eung Seok; Park, Pil-Hoon

    2015-03-30

    Leptin, a hormone mainly produced from adipose tissue, has been shown to induce proliferation of cancer cells. However, the molecular mechanisms underlying leptin-induced tumor progression have not been clearly elucidated. In the present study, we investigated the role of autophagy in leptin-induced cancer cell proliferation using human hepatoma (HepG2) and breast cancer cells (MCF-7), and tumor growth in a xenograft model. Herein, we showed that leptin treatment caused autophagy induction as assessed by increase in expression of autophagy-related genes, including beclin-1, Atg5 and LC3 II, further induction of autophagosome formation and autophagic flux. Interestingly, inhibition of autophagic process by treatment with inhibitors and LC3B gene silencing blocked leptin-induced increase in cell number and suppression of apoptosis, indicating a crucial role of autophagy in leptin-induced tumor progression. Moreover, gene silencing of p53 or FoxO3A prevented leptin-induced LC3 II protein expression, suggesting an involvement of p53/FoxO3A axis in leptin-induced autophagy activation. Leptin administration also accelerated tumor growth in BALB/c nude mice, which was found to be autophagy dependent. Taken together, our results demonstrate that leptin-induced tumor growth is mediated by autophagy induction and autophagic process would be a promising target to regulate development of cancer caused by leptin production.

  6. Autophagy induction by leptin contributes to suppression of apoptosis in cancer cells and xenograft model: Involvement of p53/FoxO3A axis

    Science.gov (United States)

    Nepal, Saroj; Kim, Mi Jin; Hong, Jin Tae; Kim, Sang Hyun; Sohn, Dong-Hwan; Lee, Sung Hee; Song, Kyung; Choi, Dong Young; Lee, Eung Seok; Park, Pil-Hoon

    2015-01-01

    Leptin, a hormone mainly produced from adipose tissue, has been shown to induce proliferation of cancer cells. However, the molecular mechanisms underlying leptin-induced tumor progression have not been clearly elucidated. In the present study, we investigated the role of autophagy in leptin-induced cancer cell proliferation using human hepatoma (HepG2) and breast cancer cells (MCF-7), and tumor growth in a xenograft model. Herein, we showed that leptin treatment caused autophagy induction as assessed by increase in expression of autophagy-related genes, including beclin-1, Atg5 and LC3 II, further induction of autophagosome formation and autophagic flux. Interestingly, inhibition of autophagic process by treatment with inhibitors and LC3B gene silencing blocked leptin-induced increase in cell number and suppression of apoptosis, indicating a crucial role of autophagy in leptin-induced tumor progression. Moreover, gene silencing of p53 or FoxO3A prevented leptin-induced LC3 II protein expression, suggesting an involvement of p53/FoxO3A axis in leptin-induced autophagy activation. Leptin administration also accelerated tumor growth in BALB/c nude mice, which was found to be autophagy dependent. Taken together, our results demonstrate that leptin-induced tumor growth is mediated by autophagy induction and autophagic process would be a promising target to regulate development of cancer caused by leptin production. PMID:25704884

  7. Transcriptional profiling of Foxo3a and Fancd2 regulated genes in mouse hematopoietic stem cells

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    Xiaoli Li

    2015-06-01

    Full Text Available Functional maintenance of hematopoietic stem cells (HSCs is constantly challenged by stresses like DNA damage and oxidative stress. Foxo factors particularly Foxo3a function to regulate the self-renewal of HSCs and contribute to the maintenance of the HSC pool during aging by providing resistance to oxidative stress. Fancd2-deficient mice had multiple hematopoietic defects including HSC loss in early development and in response to cellular stresses including oxidative stress. The cellular mechanisms underlying HSC loss in Fancd2-deficient mice include abnormal cell cycle status loss of quiescence and compromised hematopoietic repopulating capacity of HSCs. To address on a genome wide level the genes and pathways that are impacted by deletion of the Fancd2 and Foxo3a we performed microarray analysis on phenotypic HSCs (Lin−ckit+Sca-1+CD150+CD48− from Fancd2 single knockout Foxo3a single knockout and Fancd2−/−Foxo3a−/− double-knockout (dKO mice. Here we provide detailed methods and analysis on these microarray data which has been deposited in Gene Expression Omnibus (GEO: GSE64215.

  8. SIRT3 deacetylates FOXO3 to protect mitochondria against oxidative damage.

    Science.gov (United States)

    Tseng, Anne H H; Shieh, Shyan-Shu; Wang, Danny Ling

    2013-10-01

    Progressive accumulation of defective mitochondria is a common feature of aged cells. SIRT3 is a NAD(+)-dependent protein deacetylase that regulates mitochondrial function and metabolism in response to caloric restriction and stress. FOXO3 is a direct target of SIRT3 and functions as a forkhead transcription factor to govern diverse cellular responses to stress. Here we show that hydrogen peroxide induces SIRT3 to deacetylate FOXO3 at K271 and K290, followed by the upregulation of a set of genes that are essential for mitochondrial homeostasis (mitochondrial biogenesis, fission/fusion, and mitophagy). Consequently, SIRT3-mediated deacetylation of FOXO3 modulates mitochondrial mass, ATP production, and clearance of defective mitochondria. Thus, mitochondrial quantity and quality are ensured to maintain mitochondrial reserve capacity in response to oxidative damage. Maladaptation to oxidative stress is a major risk factor underlying aging and many aging-related diseases. Hence, our finding that SIRT3 deacetylates FOXO3 to protect mitochondria against oxidative stress provides a possible direction for aging-delaying therapies and disease intervention.

  9. Rnd3 in Cancer: A Review of the Evidence for Tumor Promoter or Suppressor.

    Science.gov (United States)

    Paysan, Lisa; Piquet, Léo; Saltel, Frédéric; Moreau, Violaine

    2016-11-01

    Rho-GTPases are members of the Ras superfamily of small GTPases and are general modulators of important cellular processes in tumor biology such as migration and proliferation. Among these proteins, Rnd3/RhoE, an atypical Rho-GTPase devoid of GTP hydrolytic activity, has recently been studied for its putative role in tumorigenesis. Indeed, Rnd3 is implicated in processes, such as proliferation and migration, whose deregulation is linked to cancer development and metastasis. The aim of this review is to provide an overview of the data surrounding Rnd3 deregulation in cancers, its origin, and consequences. Presented here is a comprehensive account of the expression status and biological output obtained in prostate, liver, stomach, colon, lung, and brain cancers as well as in melanoma and squamous cell carcinoma. Although there appears to be no general consensus about Rnd3 expression in cancers as this protein is differently altered according to the tumor context, these alterations overwhelmingly favor a protumorigenic role. Thus, depending on the tumor type, it may behave either as a tumor suppressor or as a tumor promoter. Importantly, the deregulation of Rnd3, in most cases, is linked to patient poor outcome.

  10. Pro-apoptotic BIM is an essential initiator of physiological endothelial cell death independent of regulation by FOXO3.

    Science.gov (United States)

    Koenig, M N; Naik, E; Rohrbeck, L; Herold, M J; Trounson, E; Bouillet, P; Thomas, T; Voss, A K; Strasser, A; Coultas, L

    2014-11-01

    The growth of new blood vessels by angiogenesis is essential for normal development, but can also cause or contribute to the pathology of numerous diseases. Recent studies have shown that BIM, a pro-apoptotic BCL2-family protein, is required for endothelial cell apoptosis in vivo, and can contribute to the anti-angiogenic effect of VEGF-A inhibitors in certain tumor models. Despite its importance, the extent to which BIM is autonomously required for physiological endothelial apoptosis remains unknown and its regulation under such conditions is poorly defined. While the transcription factor FOXO3 has been proposed to induce Bim in response to growth factor withdrawal, evidence for this function is circumstantial. We report that apoptosis was reduced in Bim(-/-) primary endothelial cells, demonstrating a cell-autonomous role for BIM in endothelial death following serum and growth factor withdrawal. In conflict with in vitro studies, BIM-dependent endothelial death in vivo did not require FOXO3. Moreover, endothelial apoptosis proceeded normally in mice lacking FOXO-binding sites in the Bim promoter. Bim mRNA was upregulated in endothelial cells starved of serum and growth factors and this was accompanied by the downregulation of miRNAs of the miR-17∼92 cluster. Bim mRNA levels were also elevated in miR-17∼92(+/-) endothelial cells cultured under steady-state conditions, suggesting that miR-17∼92 cluster miRNAs may contribute to regulating overall Bim mRNA levels in endothelial cells.

  11. AMP-activated protein kinase couples 3-bromopyruvate-induced energy depletion to apoptosis via activation of FoxO3a and upregulation of proapoptotic Bcl-2 proteins.

    Science.gov (United States)

    Bodur, Cagri; Karakas, Bahriye; Timucin, Ahmet Can; Tezil, Tugsan; Basaga, Huveyda

    2016-11-01

    Most tumors primarily rely on glycolysis rather than mitochondrial respiration for ATP production. This phenomenon, also known as Warburg effect, renders tumors more sensitive to glycolytic disturbances compared to normal cells. 3-bromopyruvate is a potent inhibitor of glycolysis that shows promise as an anticancer drug candidate. Although investigations revealed that 3-BP triggers apoptosis through ATP depletion and subsequent AMPK activation, the underlying molecular mechanisms coupling AMPK to apoptosis are poorly understood. We showed that 3-BP leads to a rapid ATP depletion which was followed by growth inhibition and Bax-dependent apoptosis in HCT116 cells. Apoptosis was accompanied with activation of caspase-9 and -3 while pretreatment with a general caspase inhibitor attenuated cell death. AMPK, p38, JNK, and Akt were phosphorylated immediately upon treatment. Pharmacological inhibition and silencing of AMPK largely inhibited 3-BP-induced apoptosis and reversed phosphorylation of JNK. Transcriptional activity of FoxO3a was dramatically increased subsequent to AMPK-mediated phosphorylation of FoxO3a at Ser413. Cell death analysis of cells transiently transfected with wt or AMPK-phosphorylation-deficient FoxO3 expression plasmids verified the contributory role of AMPK-FoxO3a axis in 3-BP-induced apoptosis. In addition, expression of proapoptotic Bcl-2 proteins Bim and Bax were upregulated in an AMPK-dependent manner. Bim was transcriptionally activated in association with FoxO3a activity, while Bax upregulation was abolished in p53-null cells. Together, these data suggest that AMPK couples 3-BP-induced metabolic disruption to intrinsic apoptosis via modulation of FoxO3a-Bim axis and Bax expression. © 2015 Wiley Periodicals, Inc.

  12. Evidence that selenium binding protein 1 is a tumor suppressor in prostate cancer.

    Directory of Open Access Journals (Sweden)

    Emmanuel Ansong

    Full Text Available Selenium-Binding Protein 1 (SBP1, SELENBP1, hSP56 is a selenium-associated protein shown to be at lower levels in tumors, and its lower levels are frequently predictive of a poor clinical outcome. Distinguishing indolent from aggressive prostate cancer is a major challenge in disease management. Associations between SBP1 levels, tumor grade, and disease recurrence following prostatectomy were investigated by duplex immunofluorescence imaging using a tissue microarray containing tissue from 202 prostate cancer patients who experienced biochemical (PSA recurrence after prostatectomy and 202 matched control patients whose cancer did not recur. Samples were matched by age, ethnicity, pathological stage and Gleason grade, and images were quantified using the Vectra multispectral imaging system. Fluorescent labels were targeted for SBP1 and cytokeratins 8/18 to restrict scoring to tumor cells, and cell-by-cell quantification of SBP1 in the nucleus and cytoplasm was performed. Nuclear SBP1 levels and the nuclear to cytoplasm ratio were inversely associated with tumor grade using linear regression analysis. Following classification of samples into quartiles based on the SBP1 levels among controls, tumors in the lowest quartile were more than twice as likely to recur compared to those in any other quartile. Inducible ectopic SBP1 expression reduced the ability of HCT-116 human tumor cells to grow in soft agar, a measure of transformation, without affecting proliferation. Cells expressing SBP1 also demonstrated a robust induction in the phosphorylation of the p53 tumor suppressor at serine 15. These data indicate that loss of SBP1 may play an independent contributing role in prostate cancer progression and its levels might be useful in distinguishing indolent from aggressive disease.

  13. PHF2 histone demethylase acts as a tumor suppressor in association with p53 in cancer.

    Science.gov (United States)

    Lee, K-H; Park, J-W; Sung, H-S; Choi, Y-J; Kim, W H; Lee, H S; Chung, H-J; Shin, H-W; Cho, C-H; Kim, T-Y; Li, S-H; Youn, H-D; Kim, S J; Chun, Y-S

    2015-05-28

    Plant homeodomain finger 2 (PHF2) has a role in epigenetic regulation of gene expression by demethylating H3K9-Me2. Several genome-wide studies have demonstrated that the chromosomal region including the PHF2 gene is often deleted in some cancers including colorectal cancer, and this finding encouraged us to investigate the tumor suppressive role of PHF2. As p53 is a critical tumor suppressor in colon cancer, we tested the possibility that PHF2 is an epigenetic regulator of p53. PHF2 was associated with p53, and thereby, promoted p53-driven gene expression in cancer cells under genotoxic stress. PHF2 converted the chromatin that is favorable for transcription by demethylating the repressive H3K9-Me2 mark. In an HCT116 xenograft model, PHF2 was found to be required for the anticancer effects of oxaliplatin and doxorubicin. In PHF2-deficient xenografts, p53 expression was profoundly induced by both drugs, but its downstream product p21 was not, suggesting that p53 cannot be activated in the absence of PHF2. To find clinical evidence about the role of PHF2, we analyzed the expressions of PHF2, p53 and p21 in human colon cancer tissues and adjacent normal tissues from patients. PHF2 was downregulated in cancer tissues and PHF2 correlated with p21 in cancers expressing functional p53. Colon and stomach cancer tissue arrays showed a positive correlation between PHF2 and p21 expressions. Informatics analyses using the Oncomine database also supported our notion that PHF2 is downregulated in colon and stomach cancers. On the basis of these findings, we propose that PHF2 acts as a tumor suppressor in association with p53 in cancer development and ensures p53-mediated cell death in response to chemotherapy.

  14. The tumor suppressor HHEX inhibits axon growth when prematurely expressed in developing central nervous system neurons.

    Science.gov (United States)

    Simpson, Matthew T; Venkatesh, Ishwariya; Callif, Ben L; Thiel, Laura K; Coley, Denise M; Winsor, Kristen N; Wang, Zimei; Kramer, Audra A; Lerch, Jessica K; Blackmore, Murray G

    2015-09-01

    Neurons in the embryonic and peripheral nervous system respond to injury by activating transcriptional programs supportive of axon growth, ultimately resulting in functional recovery. In contrast, neurons in the adult central nervous system (CNS) possess a limited capacity to regenerate axons after injury, fundamentally constraining repair. Activating pro-regenerative gene expression in CNS neurons is a promising therapeutic approach, but progress is hampered by incomplete knowledge of the relevant transcription factors. An emerging hypothesis is that factors implicated in cellular growth and motility outside the nervous system may also control axon growth in neurons. We therefore tested sixty-nine transcription factors, previously identified as possessing tumor suppressive or oncogenic properties in non-neuronal cells, in assays of neurite outgrowth. This screen identified YAP1 and E2F1 as enhancers of neurite outgrowth, and PITX1, RBM14, ZBTB16, and HHEX as inhibitors. Follow-up experiments are focused on the tumor suppressor HHEX, one of the strongest growth inhibitors. HHEX is widely expressed in adult CNS neurons, including corticospinal tract neurons after spinal injury, but is present only in trace amounts in immature cortical neurons and adult peripheral neurons. HHEX overexpression in early postnatal cortical neurons reduced both initial axonogenesis and the rate of axon elongation, and domain deletion analysis strongly implicated transcriptional repression as the underlying mechanism. These findings suggest a role for HHEX in restricting axon growth in the developing CNS, and substantiate the hypothesis that previously identified oncogenes and tumor suppressors can play conserved roles in axon extension. Copyright © 2015 Elsevier Inc. All rights reserved.

  15. Tumor suppressor BRCA1 epigenetically controls oncogenic microRNA-155

    Science.gov (United States)

    Chang, Suhwan; Wang, Rui-Hong; Akagi, Keiko; Kim, Kyung-Ae; Martin, Betty K; Cavallone, Luca; Haines, Diana C; Basik, Mark; Mai, Phuong; Poggi, Elizabeth; Isaacs, Claudine; Looi, Lai M; Mun, Kein S; Greene, Mark H; Byers, Stephen W; Teo, Soo H; Deng, Chu-Xia; Sharan, Shyam K

    2012-01-01

    BRCA1, a well-known tumor suppressor with multiple interacting partners, is predicted to have diverse biological functions. However, so far its only well-established role is in the repair of damaged DNA and cell cycle regulation. In this regard, the etiopathological study of low-penetrant variants of BRCA1 provides an opportunity to uncover its other physiologically important functions. Using this rationale, we studied the R1699Q variant of BRCA1, a potentially moderate-risk variant, and found that it does not impair DNA damage repair but abrogates the repression of microRNA-155 (miR-155), a bona fide oncomir. Mechanistically, we found that BRCA1 epigenetically represses miR-155 expression via its association with HDAC2, which deacetylates histones H2A and H3 on the miR-155 promoter. We show that overexpression of miR-155 accelerates whereas the knockdown of miR-155 attenuates the growth of tumor cell lines in vivo. Our findings demonstrate a new mode of tumor suppression by BRCA1 and suggest that miR-155 is a potential therapeutic target for BRCA1-deficient tumors. PMID:21946536

  16. Alterations of tumor suppressor gene p16INK4a in pancreatic ductal carcinoma

    Directory of Open Access Journals (Sweden)

    Radotra Bishan

    2005-06-01

    Full Text Available Abstract Background Cell cycle inhibitor and tumor suppressor gene p16 / MTS-1 has been reported to be altered in a variety of human tumors. The purpose of the study was to evaluate primary pancreatic ductal adenocarcinomas for potentially inactivating p16 alterations. Methods We investigated the status of p16 gene by polymerase chain reaction (PCR, nonradioisotopic single strand conformation polymorphism (SSCP, DNA sequencing and hypermethylation analysis in 25 primary resected ductal adenocarcinomas. In addition, we investigated p16 protein expression in these cases by immunohistochemistry (IHC using a monoclonal antibody clone (MS-887-PO. Results Out of the 25 samples analyzed and compared to normal pancreatic control tissues, the overall frequency of p16 alterations was 80% (20/25. Aberrant promoter methylation was the most common mechanism of gene inactivation present in 52% (13/25 cases, followed by coding sequence mutations in 16% (4/25 cases and presumably homozygous deletion in 12% (3/25 cases. These genetic alterations correlated well with p16 protein expression as complete loss of p16 protein was found in 18 of 25 tumors (72%. Conclusion These findings confirm that loss of p16 function could be involved in pancreatic cancer and may explain at least in part the aggressive behaviour of this tumor type.

  17. gld-1, a tumor suppressor gene required for oocyte development in Caenorhabditis elegans

    Energy Technology Data Exchange (ETDEWEB)

    Francis, R.; Schedl, T. [Washington Univ. School of Medicine, St. Louis, MO (United States); Barton, M.K.; Kimble, J. [Univ. of Wisconsin, Madison, WI (United States)

    1995-02-01

    We have characterized 31 mutations in the gld-1 (defective in germline development) gene of Caenorhabditis elegans. In gld-1 (null) hermaphrodites, oogenesis is abolished and a germline tumor forms where oocyte development would normally occur. By contrast, gld-1 (null) males are unaffected. The hermaphrodite germline tumor appears to derive from germ cells that enter the meiotic pathway normally but then exit pachytene and return to the mitotic cycle. Certain gld-1 partial loss-of-function mutations also abolish oogenesis, but germ cells arrest in pachytene rather than returning to mitosis. Our results indicate that gld-1 is a tumor suppressor gene required for oocyte development. The tumorous phenotype suggests that gld-1(+) may function to negatively regulate proliferation during meiotic prophase and/or act to direct progression through meiotic prophase. We also show that gld-1(+) has an additional nonessential role in germline sex determination: promotion of hermaphrodite spermatogenesis. This function of gld-1 is inferred from a haplo-insufficient phenotype and from the properties of gain-of-function gld-1 mutations that cause alterations in the sexual identity of germ cells. 69 refs., 10 figs., 8 tabs.

  18. Alterations of tumor suppressor gene p16INK4a in pancreatic ductal carcinoma

    Science.gov (United States)

    Attri, Jyotika; Srinivasan, Radhika; Majumdar, Siddhartha; Radotra, Bishan Dass; Wig, Jaidev

    2005-01-01

    Background Cell cycle inhibitor and tumor suppressor gene p16 / MTS-1 has been reported to be altered in a variety of human tumors. The purpose of the study was to evaluate primary pancreatic ductal adenocarcinomas for potentially inactivating p16 alterations. Methods We investigated the status of p16 gene by polymerase chain reaction (PCR), nonradioisotopic single strand conformation polymorphism (SSCP), DNA sequencing and hypermethylation analysis in 25 primary resected ductal adenocarcinomas. In addition, we investigated p16 protein expression in these cases by immunohistochemistry (IHC) using a monoclonal antibody clone (MS-887-PO). Results Out of the 25 samples analyzed and compared to normal pancreatic control tissues, the overall frequency of p16 alterations was 80% (20/25). Aberrant promoter methylation was the most common mechanism of gene inactivation present in 52% (13/25) cases, followed by coding sequence mutations in 16% (4/25) cases and presumably homozygous deletion in 12% (3/25) cases. These genetic alterations correlated well with p16 protein expression as complete loss of p16 protein was found in 18 of 25 tumors (72%). Conclusion These findings confirm that loss of p16 function could be involved in pancreatic cancer and may explain at least in part the aggressive behaviour of this tumor type. PMID:15985168

  19. Tumor-Suppressor Function of SPARC-Like Protein 1/Hevin in Pancreatic Cancer

    Directory of Open Access Journals (Sweden)

    Irene Esposito

    2007-01-01

    Full Text Available SPARC-like protein 1 (SPARCL1, a member of the SPARC family, is downregulated in various tumors. In the present study, the expression and localization of SPARCL1 were analyzed in a wide range of nontumorous and neoplastic pancreatic tissues by quantitative reverse transcription-polymerase chain reaction, laser capture microdissection, microarray analysis, and immunohistochemistry. For functional analysis, proliferation and invasion assays were used in cultured pancreatic cancer cells. Pancreatic ductal adenocarcinoma (PDAC and other pancreatic neoplasms exhibited increased SPARCL1 mRNA levels compared to those of the normal pancreas. SPARCL1 mRNA levels were low to absent in microdissected and cultured pancreatic cancer cells, and promoter demethylation increased SPARCL1 levels only slightly in three of eight cell lines. SPARCL1 was observed in small capillaries in areas of inflammation/tumor growth and in some islet cells. In PDAC, 15.4% of vessels were SPARCL1-positive. In contrast, the percentage of SPARCL1-positive vessels was higher in chronic pancreatitis and benign and borderline pancreatic tumors. Recombinant SPARCL1 inhibited pancreatic cancer cell invasion and exerted moderate growth-inhibitory effects. In conclusion, SPARCL1 expression in pancreatic tissues is highly correlated with level of vascularity. Its antiinvasive effects and reduced expression in metastasis indicate tumor-suppressor function.

  20. Tumor-suppressor genes that escape from X-inactivation contribute to cancer sex bias.

    Science.gov (United States)

    Dunford, Andrew; Weinstock, David M; Savova, Virginia; Schumacher, Steven E; Cleary, John P; Yoda, Akinori; Sullivan, Timothy J; Hess, Julian M; Gimelbrant, Alexander A; Beroukhim, Rameen; Lawrence, Michael S; Getz, Gad; Lane, Andrew A

    2017-01-01

    There is a striking and unexplained male predominance across many cancer types. A subset of X-chromosome genes can escape X-inactivation, which would protect females from complete functional loss by a single mutation. To identify putative 'escape from X-inactivation tumor-suppressor' (EXITS) genes, we examined somatic alterations from >4,100 cancers across 21 tumor types for sex bias. Six of 783 non-pseudoautosomal region (PAR) X-chromosome genes (ATRX, CNKSR2, DDX3X, KDM5C, KDM6A, and MAGEC3) harbored loss-of-function mutations more frequently in males (based on a false discovery rate genes (Fisher's exact P genes that escape X-inactivation were observed in combined analysis across many cancers and in several individual tumor types, suggesting a generalized phenomenon. We conclude that biallelic expression of EXITS genes in females explains a portion of the reduced cancer incidence in females as compared to males across a variety of tumor types.

  1. Cdh11 Acts as a Tumor Suppressor in a Murine Retinoblastoma Model by Facilitating Tumor Cell Death

    Science.gov (United States)

    Marchong, Mellone N.; Yurkowski, Christine; Ma, Clement; Spencer, Clarellen; Pajovic, Sanja; Gallie, Brenda L.

    2010-01-01

    CDH11 gene copy number and expression are frequently lost in human retinoblastomas and in retinoblastomas arising in TAg-RB mice. To determine the effect of Cdh11 loss in tumorigenesis, we crossed Cdh11 null mice with TAg-RB mice. Loss of Cdh11 had no gross morphological effect on the developing retina of Cdh11 knockout mice, but led to larger retinal volumes in mice crossed with TAg-RB mice (p = 0.01). Mice null for Cdh11 presented with fewer TAg-positive cells at postnatal day 8 (PND8) (p = 0.01) and had fewer multifocal tumors at PND28 (p = 0.016), compared to mice with normal Cdh11 alleles. However, tumor growth was faster in Cdh11-null mice between PND8 and PND84 (p = 0.003). In tumors of Cdh11-null mice, cell death was decreased 5- to 10-fold (p<0.03 for all markers), while proliferation in vivo remained unaffected (p = 0.121). Activated caspase-3 was significantly decreased and β-catenin expression increased in Cdh11 knockdown experiments in vitro. These data suggest that Cdh11 displays tumor suppressor properties in vivo and in vitro in murine retinoblastoma through promotion of cell death. PMID:20421947

  2. Cdh11 acts as a tumor suppressor in a murine retinoblastoma model by facilitating tumor cell death.

    Directory of Open Access Journals (Sweden)

    Mellone N Marchong

    2010-04-01

    Full Text Available CDH11 gene copy number and expression are frequently lost in human retinoblastomas and in retinoblastomas arising in TAg-RB mice. To determine the effect of Cdh11 loss in tumorigenesis, we crossed Cdh11 null mice with TAg-RB mice. Loss of Cdh11 had no gross morphological effect on the developing retina of Cdh11 knockout mice, but led to larger retinal volumes in mice crossed with TAg-RB mice (p = 0.01. Mice null for Cdh11 presented with fewer TAg-positive cells at postnatal day 8 (PND8 (p = 0.01 and had fewer multifocal tumors at PND28 (p = 0.016, compared to mice with normal Cdh11 alleles. However, tumor growth was faster in Cdh11-null mice between PND8 and PND84 (p = 0.003. In tumors of Cdh11-null mice, cell death was decreased 5- to 10-fold (p<0.03 for all markers, while proliferation in vivo remained unaffected (p = 0.121. Activated caspase-3 was significantly decreased and beta-catenin expression increased in Cdh11 knockdown experiments in vitro. These data suggest that Cdh11 displays tumor suppressor properties in vivo and in vitro in murine retinoblastoma through promotion of cell death.

  3. Oncogenic EGFR Represses the TET1 DNA Demethylase to Induce Silencing of Tumor Suppressors in Cancer Cells

    Directory of Open Access Journals (Sweden)

    Matteo Forloni

    2016-07-01

    Full Text Available Oncogene-induced DNA methylation-mediated transcriptional silencing of tumor suppressors frequently occurs in cancer, but the mechanism and functional role of this silencing in oncogenesis are not fully understood. Here, we show that oncogenic epidermal growth factor receptor (EGFR induces silencing of multiple unrelated tumor suppressors in lung adenocarcinomas and glioblastomas by inhibiting the DNA demethylase TET oncogene family member 1 (TET1 via the C/EBPα transcription factor. After oncogenic EGFR inhibition, TET1 binds to tumor suppressor promoters and induces their re-expression through active DNA demethylation. Ectopic expression of TET1 potently inhibits lung and glioblastoma tumor growth, and TET1 knockdown confers resistance to EGFR inhibitors in lung cancer cells. Lung cancer samples exhibited reduced TET1 expression or TET1 cytoplasmic localization in the majority of cases. Collectively, these results identify a conserved pathway of oncogenic EGFR-induced DNA methylation-mediated transcriptional silencing of tumor suppressors that may have therapeutic benefits for oncogenic EGFR-mediated lung cancers and glioblastomas.

  4. Identification of a third protein 4.1 tumor suppressor, protein 4.1R, in meningioma pathogenesis

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    Robb, Victoria A.; Li, Wen; Gascard, Philippe; Perry, Arie; Mohandas, Narla; Gutmann, David H.

    2003-06-11

    Meningiomas are common tumors of the central nervous system, however, the mechanisms under lying their pathogenesis are largely undefined. Two members of the Protein 4.1 super family, the neuro fibromatosis 2 (NF2) gene product (merlin/schwannomin) and Protein 4.1B have been implicated as meningioma tumor suppressors. In this report, we demonstrate that another Protein 4.1 family member, Protein 4.1R, also functions as a meningioma tumor suppressor. Based on the assignment of the Protein 4.1R gene to chromosome 1p32-36, a common region of deletion observed in meningiomas, we analyzed Protein 4.1R expression in meningioma cell lines and surgical tumor specimens. We observed loss of Protein 4.1R protein expression in two meningioma cell lines (IOMM-Lee, CH157-MN) by Western blotting as well as in 6 of 15 sporadic meningioma as by immuno histo chemistry (IHC). Analysis of a subset of these sporadic meningiomas by fluorescent in situ hybridization (FISH) with a Protein 4.1R specific probe demonstrated 100 percent concordance with the IHC results. In support of a meningioma tumor suppressor function, over expression of Protein 4.1R resulted in suppression of IOMM-Lee and CH157MN cell proliferation. Similar to the Protein 4.1B and merlin meningioma tumor suppressors, Protein 4.1R localization in the membrane fraction increased significantly under conditions of growth arrest in vitro. Lastly, Protein 4.1R interacted with some known merlin/Protein 4.1B interactors such as CD44 and bII-spectrin, but did not associate with the Protein 4.1B interactors 14-3-3 and PRMT3 or the merlin binding proteins SCHIP-1 and HRS. Collectively, these results suggest that Protein 4.1R functions as an important tumor suppressor important in the molecular pathogenesis of meningioma.

  5. [Correlation of size of the primary tumor and axillary node status with the p53 tumor suppressor gene in carcinoma of the breast].

    Science.gov (United States)

    Topić, Brano; Stanković, N; Savjak, D; Grbić, S

    2002-01-01

    Correlation of standard pathomorphological prognostic parameters, primary tumor size and axillary nodal status with new prognostic factor in breast carcinoma: tumor suppressor gene p53 was analyzed. The studied sample included 65 women who underwent surgery for breast carcinoma at the Surgical Clinic of Clinical Center Banja Luka, from January 1st 1997 till January 1st 1999. Statistical data analysis was performed and correlation of prognostic factors was determined. The majority of authors in this field agree that the primary tumor size and axillary nodal status are the two most important prognostic factors. These factors are the best predictors of prognosis and survival of women who had the tumor and were operated on. Tumor markers were immunohistochemically determined in the last ten years and, according to the majority of authors, are still considered the additional or relative prognostic factors in breast carcinoma. Their prognostic value and significance increase almost daily. Most frequently determined tumor markers are bcl-2, pS2, Ki-67 and p53. There was a positive, directly proportional relationship between primary tumor size and tumor suppressor gene p53, but there was no positive correlation between the axillary nodal status and tumor suppressor gene p53. Significance of determination of new tumor markers as the prognostic factors was emphasized. These markers represent a powerful tool in the early detection and prevention of breast carcinoma.

  6. 氧化应激中ROS对FOXO3 a转录因子的调控作用研究进展%Redox regulation of FOXO3 a transcription factor

    Institute of Scientific and Technical Information of China (English)

    李昂; 邢雅琪; 李晓霞; 章吉威; 郭会彩

    2016-01-01

    活性氧( reactive oxygen species,ROS)介导的氧化应激参与多种细胞信号转导过程,FOXO3a转录因子是氧化应激中多个信号通路的交汇点,ROS对FOXO3a存在着复杂的调控作用。由于FOXO3a在细胞增殖、细胞周期阻滞、ROS清除和诱导细胞凋亡中发挥复杂而重要的作用,已经成为氧化应激损伤的研究热点之一。该文对氧化应激损伤中FOXO3a的活性调节机制及其靶基因进行了综述,为FOXO3a靶向调控氧化应激和临床治疗相关疾病开辟了新的思路。%ROS-mediated oxidative stress involved in a variety of cellular signal transduction, FOXO3a transcription factor is an intersection in regulating a variety of cellular oxidative stress. FoxO3a has been extensively studied in regulating oxidative stress because of its rather complex and pivotal regulation of cell proliferation, cell cycle arrest, ROS scavenging and apoptosis. This review will elucidate the FOXO3a’s regulatory mechanisms and describe the target genes involved. It will also provide the clinical significance and strategies to target FOXO3a to regulate oxidative stress.

  7. The ARF Tumor Suppressor Regulates Bone Remodeling and Osteosarcoma Development in Mice

    Science.gov (United States)

    Harding, John C.; Deng, Hongju; Shea, Lauren K.; Eagleton, Mark C.; Niewiesk, Stefan; Lairmore, Michael D.; Piwnica-Worms, David; Rosol, Thomas J.; Weber, Jason D.; Ratner, Lee; Weilbaecher, Katherine N.

    2010-01-01

    The ARF tumor suppressor regulates p53 as well as basic developmental processes independent of p53, including osteoclast activation, by controlling ribosomal biogenesis. Here we provide evidence that ARF is a master regulator of bone remodeling and osteosarcoma (OS) development in mice. Arf-/- mice displayed increased osteoblast (OB) and osteoclast (OC) activity with a significant net increase in trabecular bone volume. The long bones of Arf-/- mice had increased expression of OB genes while Arf-/- OB showed enhanced differentiation in vitro. Mice transgenic for the Tax oncogene develop lymphocytic tumors with associated osteolytic lesions, while Tax+Arf-/- mice uniformly developed spontaneous OS by 7 months of age. Tax+Arf-/- tumors were well differentiated OS characterized by an abundance of new bone with OC recruitment, expressed OB markers and displayed intact levels of p53 mRNA and reduced Rb transcript levels. Cell lines established from OS recapitulated characteristics of the primary tumor, including the expression of mature OB markers and ability to form mineralized tumors when transplanted. Loss of heterozygosity in OS tumors arising in Tax+Arf+/- mice emphasized the necessity of ARF-loss in OS development. Hypothesizing that inhibition of ARF-regulated bone remodeling would repress development of OS, we demonstrated that treatment of Tax+Arf-/- mice with zoledronic acid, a bisphosphonate inhibitor of OC activity and repressor of bone turnover, prevented or delayed the onset of OS. These data describe a novel role for ARF as a regulator of bone remodeling through effects on both OB and OC. Finally, these data underscore the potential of targeting bone remodeling as adjuvant therapy or in patients with genetic predispositions to prevent the development of OS. PMID:21209895

  8. CFTR is a tumor suppressor gene in murine and human intestinal cancer.

    Science.gov (United States)

    Than, B L N; Linnekamp, J F; Starr, T K; Largaespada, D A; Rod, A; Zhang, Y; Bruner, V; Abrahante, J; Schumann, A; Luczak, T; Niemczyk, A; O'Sullivan, M G; Medema, J P; Fijneman, R J A; Meijer, G A; Van den Broek, E; Hodges, C A; Scott, P M; Vermeulen, L; Cormier, R T

    2016-08-11

    CFTR, the cystic fibrosis (CF) gene, encodes for the CFTR protein that plays an essential role in anion regulation and tissue homeostasis of various epithelia. In the gastrointestinal (GI) tract CFTR promotes chloride and bicarbonate secretion, playing an essential role in ion and acid-base homeostasis. Cftr has been identified as a candidate driver gene for colorectal cancer (CRC) in several Sleeping Beauty DNA transposon-based forward genetic screens in mice. Further, recent epidemiological and clinical studies indicate that CF patients are at high risk for developing tumors in the colon. To investigate the effects of CFTR dysregulation on GI cancer, we generated Apc(Min) mice that carried an intestinal-specific knockout of Cftr. Our results indicate that Cftr is a tumor suppressor gene in the intestinal tract as Cftr mutant mice developed significantly more tumors in the colon and the entire small intestine. In Apc(+/+) mice aged to ~1 year, Cftr deficiency alone caused the development of intestinal tumors in >60% of mice. Colon organoid formation was significantly increased in organoids created from Cftr mutant mice compared with wild-type controls, suggesting a potential role of Cftr in regulating the intestinal stem cell compartment. Microarray data from the Cftr-deficient colon and the small intestine identified dysregulated genes that belong to groups of immune response, ion channel, intestinal stem cell and other growth signaling regulators. These associated clusters of genes were confirmed by pathway analysis using Ingenuity Pathway Analysis and gene set enrichment analysis (GSEA). We also conducted RNA Seq analysis of tumors from Apc(+/+) Cftr knockout mice and identified sets of genes dysregulated in tumors including altered Wnt β-catenin target genes. Finally we analyzed expression of CFTR in early stage human CRC patients stratified by risk of recurrence and found that loss of expression of CFTR was significantly associated with poor disease

  9. The tumor suppressor gene RBM5 inhibits lung adenocarcinoma cell growth and induces apoptosis

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    Shao Chen

    2012-08-01

    Full Text Available Abstract Background The loss of tumor suppressor gene (TSG function is a critical step in the pathogenesis of human lung cancer. RBM5 (RNA-binding motif protein 5, also named H37/LUCA-15 gene from chromosome 3p21.3 demonstrated tumor suppressor activity. However, the role of RBM5 played in the occurrence and development of lung cancer is still not well understood. Method Paired non-tumor and tumor tissues were obtained from 30 adenocarcinomas. The expression of RBM5 mRNA and protein was examined by RT-PCR and Western blot. A549 cell line was used to determine the apoptotic function of RBM5 in vitro. A549 cells were transiently transfected with pcDNA3.1-RBM5. AnnexinV analysis was performed by flow cytometry. Expression of Bcl-2, cleaved caspase-3, caspase-9 and PAPP proteins in A549 lung cancer cells and the A549 xenograft BALB/c nude mice model was determined by Western blot. Tumor suppressor activity of RBM5 was also examined in the A549 xenograft model treated with pcDNA3.1-RBM5 plasmid carried by attenuated Salmonella typhi Ty21a. Result The expression of RBM5 mRNA and protein was decreased significantly in adenocarcinoma tissues compared to that in the non-tumor tissues. In addition, as compared to the vector control, a significant growth inhibition of A549 lung cancer cells was observed when transfected with pcDNA3.1-RBM5 as determined by cell proliferation assay. We also found that overexpression of RBM5 induced both early and late apoptosis in A549 cells using AnnexinV/PI staining as determined by flow cytometry. Furthermore, the expression of Bcl-2 protein was decreased, whereas the expression of cleaved caspase-3, caspase-9 and PARP proteins was significantly increased in the RBM5 transfected cells; similarly, expression of decreased Bcl-2 and increased cleaved caspase-3 proteins was also examined in the A549 xenograft model. More importantly, we showed that accumulative and stable overexpression of RBM5 in the A549 xenograft BALB

  10. The tumor suppressor PTEN and the PDK1 kinase regulate formation of the columnar neural epithelium.

    Science.gov (United States)

    Grego-Bessa, Joaquim; Bloomekatz, Joshua; Castel, Pau; Omelchenko, Tatiana; Baselga, José; Anderson, Kathryn V

    2016-01-26

    Epithelial morphogenesis and stability are essential for normal development and organ homeostasis. The mouse neural plate is a cuboidal epithelium that remodels into a columnar pseudostratified epithelium over the course of 24 hr. Here we show that the transition to a columnar epithelium fails in mutant embryos that lack the tumor suppressor PTEN, although proliferation, patterning and apical-basal polarity markers are normal in the mutants. The Pten phenotype is mimicked by constitutive activation of PI3 kinase and is rescued by the removal of PDK1 (PDPK1), but does not depend on the downstream kinases AKT and mTORC1. High resolution imaging shows that PTEN is required for stabilization of planar cell packing in the neural plate and for the formation of stable apical-basal microtubule arrays. The data suggest that appropriate levels of membrane-associated PDPK1 are required for stabilization of apical junctions, which promotes cell elongation, during epithelial morphogenesis.

  11. Analysis of tumor suppressor genes based on gene ontology and the KEGG pathway.

    Science.gov (United States)

    Yang, Jing; Chen, Lei; Kong, Xiangyin; Huang, Tao; Cai, Yu-Dong

    2014-01-01

    Cancer is a serious disease that causes many deaths every year. We urgently need to design effective treatments to cure this disease. Tumor suppressor genes (TSGs) are a type of gene that can protect cells from becoming cancerous. In view of this, correct identification of TSGs is an alternative method for identifying effective cancer therapies. In this study, we performed gene ontology (GO) and pathway enrichment analysis of the TSGs and non-TSGs. Some popular feature selection methods, including minimum redundancy maximum relevance (mRMR) and incremental feature selection (IFS), were employed to analyze the enrichment features. Accordingly, some GO terms and KEGG pathways, such as biological adhesion, cell cycle control, genomic stability maintenance and cell death regulation, were extracted, which are important factors for identifying TSGs. We hope these findings can help in building effective prediction methods for identifying TSGs and thereby, promoting the discovery of effective cancer treatments.

  12. The Regulatory Mechanisms of Tumor Suppressor P16INK4A and Relevance to Cancer†

    Science.gov (United States)

    Li, Junan; Poi, Ming Jye; Tsai, Ming-Daw

    2011-01-01

    P16INK4A (also known as P16 and MTS1), a protein consisting exclusively of four ankyrin repeats, is recognized as a tumor suppressor mainly due to the prevalence of genetic inactivation of the p16INK4A (or CDKN2A) gene in virtually all types of human cancers. However, it has also been shown that elevated expression (up-regulation) of P16 is involved in cellular senescence, aging, and cancer progression, indicating that the regulation of P16 is critical for its function. Here, we discuss the regulatory mechanisms of P16 function at the DNA level, the transcription level, and the posttranscriptional level, as well as their implications in the structure-function relationship of P16 and in human cancers. PMID:21619050

  13. Redox regulation of tumor suppressor PTEN in cancer and aging (Review).

    Science.gov (United States)

    Kitagishi, Yasuko; Matsuda, Satoru

    2013-03-01

    Phosphatase and tensin homologue deleted on chromosome 10 (PTEN) has been shown to act as a tumor suppressor whose function includes important roles in regulating oxidative stress, indicating a potential role in oxidative damage-associated cancer. Accumulating evidence has revealed that PTEN also acts as a pivotal determinant of cell fate, regarding senescence and apoptosis, which is mediated by intracellular reactive oxygen species (ROS) generation. Cells are continuously exposed to ROS, which represent mutagens and are thought to be a major contributor to cancer and the aging process. Therefore, cellular ROS sensing and metabolism are firmly regulated by a variety of proteins involved in the redox mechanism. In this review, PTEN and the roles of oxidative stress in phosphoinositide-3 kinase/AKT signaling are summarized with a focus on the links between the pathways and ROS in cancer and aging.

  14. The metabolic/pH sensor soluble adenylyl cyclase is a tumor suppressor protein

    Science.gov (United States)

    Ramos-Espiritu, Lavoisier; Diaz, Ana; Nardin, Charlee; Saviola, Anthony J.; Shaw, Fiona; Plitt, Tamar; Yang, Xia; Wolchok, Jedd; Pirog, Edyta C.; Desman, Garrett; Sboner, Andrea; Zhang, Tuo; Xiang, Jenny; Merghoub, Taha; Levin, Lonny R.; Buck, Jochen; Zippin, Jonathan H.

    2016-01-01

    cAMP signaling pathways can both stimulate and inhibit the development of cancer; however, the sources of cAMP important for tumorigenesis remain poorly understood. Soluble adenylyl cyclase (sAC) is a non-canonical, evolutionarily conserved, nutrient- and pH-sensing source of cAMP. sAC has been implicated in the metastatic potential of certain cancers, and it is differentially localized in human cancers as compared to benign tissues. We now show that sAC expression is reduced in many human cancers. Loss of sAC increases cellular transformation in vitro and malignant progression in vivo. These data identify the metabolic/pH sensor soluble adenylyl cyclase as a previously unappreciated tumor suppressor protein. PMID:27323809

  15. Retinoblastoma tumor suppressor functions shared by stem cell and cancer cell strategies

    Institute of Scientific and Technical Information of China (English)

    Susumu; Kohno; Shunsuke; Kitajima; Nobunari; Sasaki; Chiaki; Takahashi

    2016-01-01

    Carcinogenic transformation of somatic cells resembles nuclear reprogramming toward the generation of pluripotent stem cells.These events share eternal escape from cellular senescence,continuous self-renewal in limited but certain population of cells,and refractoriness to terminal differentiation while maintaining the potential to differentiate into cells of one or multiple lineages.As represented by several oncogenes those appeared to be first keys to pluripotency,carcinogenesis and nuclear reprogramming seem to share a number of core mechanisms.The retinoblastoma tumor suppressor product retinoblastoma(RB)seems to be critically involved in both events in highly complicated manners.However,disentangling such complicated interactions has enabled us to better understand how stem cell strategies are shared by cancer cells.This review covers recent findings on RB functions related to stem cells and stem cell-like behaviors of cancer cells.

  16. Methylation of HPV and a tumor suppressor gene reveals anal cancer and precursor lesions

    Science.gov (United States)

    Lorincz, Attila T.; Nathan, Mayura; Reuter, Caroline; Warman, Rhian; Thaha, Mohamed A.; Sheaff, Michael; Vasiljevic, Natasa; Ahmad, Amar; Cuzick, Jack; Sasieni, Peter

    2017-01-01

    We studied DNA methylation patterns of human papillomavirus (HPV) and tumor suppressor gene EPB41L3 in 148 anal and perianal biopsies to determine whether high levels of methylation would be associated with anal intraepithelial neoplasia (AIN). The most prevalent HPV type was HPV16, detected in 54% of the 30 benign biopsies, 33% of the 43 low-grade AIN (lgAIN), 82% of the 59 high grade AIN (hgAIN) and 4 of the 5 anal cancers. A methylation score was developed (0.561*HPV16me+0.439*EPB41L3) which had increasing values with severity of disease: the mean was 8.1% in benign, 13.2% in lgAIN, 22.3% in hgAIN and 49.3% in cancers (p anal disease. PMID:28881579

  17. Discovery of novel tumor suppressor p53 response elements using information theory

    Science.gov (United States)

    Lyakhov, Ilya G.; Krishnamachari, Annangarachari; Schneider, Thomas D.

    2008-01-01

    An accurate method for locating genes under tumor suppressor p53 control that is based on a well-established mathematical theory and built using naturally occurring, experimentally proven p53 sites is essential in understanding the complete p53 network. We used a molecular information theory approach to create a flexible model for p53 binding. By searching around transcription start sites in human chromosomes 1 and 2, we predicted 16 novel p53 binding sites and experimentally demonstrated that 15 of the 16 (94%) sites were bound by p53. Some were also bound by the related proteins p63 and p73. Thirteen of the adjacent genes were controlled by at least one of the proteins. Eleven of the 16 sites (69%) had not been identified previously. This molecular information theory approach can be extended to any genetic system to predict new sites for DNA-binding proteins. PMID:18495754

  18. PTEN: a default gate-keeping tumor suppressor with a versatile tail

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The tumor suppressor PTEN controls a variety of biological processes including cell proliferation, growth, migration, and death. As a master cellular regulator, PTEN itself is also subjected to deliberated regulation to ensure its proper function. Defects in PTEN regulation have a profound impact on carcinogenesis. In this review, we briefly discuss recent advances concerning PTEN regulation and how such knowledge facilitates our understanding and further exploration of PTEN biology. The carboxyl-tail of PTEN, which appears to be associated with multiple types of posttranslational regulation, will be under detailed scrutiny. Further, a comparative analysis of PTEN and p53 suggests while p53 needs to be activated to suppress tumorigenesis (a dormant gatekeeper), PTEN is probably a constitutive surveillant against cancer development, thus a default gatekeeper.

  19. Protein Phosphatase 2A Reactivates FOXO3a through a Dynamic Interplay with 14-3-3 and AKT

    Science.gov (United States)

    Singh, Amrik; Ye, Min; Bucur, Octavian; Zhu, Shudong; Tanya Santos, Maria; Rabinovitz, Isaac; Wei, Wenyi; Gao, Daming; Hahn, William C.

    2010-01-01

    Forkhead box transcription factor FOXO3a, a key regulator of cell survival, is regulated by reversible phosphorylation and subcellular localization. Although the kinases regulating FOXO3a activity have been characterized, the role of protein phosphatases (PP) in the control of FOXO3a subcellular localization and function is unknown. In this study, we detected a robust interaction between FOXO3a and PP2A. We further demonstrate that 14-3-3, while not impeding the interaction between PP2A and FOXO3a, restrains its activity toward AKT phosphorylation sites T32/S253. Disruption of PP2A function revealed that after AKT inhibition, PP2A-mediated dephosphorylation of T32/S253 is required for dissociation of 14-3-3, nuclear translocation, and transcriptional activation of FOXO3a. Our findings reveal that distinct phosphatases dephosphorylate conserved AKT motifs within the FOXO family and that PP2A is entwined in a dynamic interplay with AKT and 14-3-3 to directly regulate FOXO3a subcellular localization and transcriptional activation. PMID:20110348

  20. miR-182 attenuates atrophy-related gene expression by targeting FoxO3 in skeletal muscle.

    Science.gov (United States)

    Hudson, Matthew B; Rahnert, Jill A; Zheng, Bin; Woodworth-Hobbs, Myra E; Franch, Harold A; Price, S Russ

    2014-08-15

    Skeletal muscle atrophy occurs in response to a variety of conditions including chronic kidney disease, diabetes, cancer, and elevated glucocorticoids. MicroRNAs (miR) may play a role in the wasting process. Activation of the forkhead box O3 (FoxO3) transcription factor causes skeletal muscle atrophy in patients, animals, and cultured cells by increasing the expression of components of the ubiquitin-proteasome and autophagy-lysosome proteolytic systems. To identify microRNAs that potentially modulate the atrophy process, an in silico target analysis was performed and miR-182 was predicted to target FoxO3 mRNA. Using a combination of immunoblot analysis, quantitative real-time RT-PCR, and FoxO3 3'-UTR luciferase reporter genes, miR-182 was confirmed to regulate FoxO3 expression in C2C12 myotubes. Transfection of miR-182 into muscle cells decreased FoxO3 mRNA 30% and FoxO3 protein 67% (P muscle atrophy decreased miR-182 expression by 63% (P muscle of rats injected with streptozotocin to induce diabetes compared with controls. Finally, miR-182 was present in exosomes isolated from the media of C2C12 myotubes and Dex increased its abundance. These data identify miR-182 as an important regulator of FoxO3 expression that participates in the control of atrophy-inducing genes during catabolic diseases.

  1. Frequent attenuation of the WWOX tumor suppressor in osteosarcoma is associated with increased tumorigenicity and aberrant RUNX2 expression.

    Science.gov (United States)

    Kurek, Kyle C; Del Mare, Sara; Salah, Zaidoun; Abdeen, Suhaib; Sadiq, Hussain; Lee, Suk-Hee; Gaudio, Eugenio; Zanesi, Nicola; Jones, Kevin B; DeYoung, Barry; Amir, Gail; Gebhardt, Mark; Warman, Matthew; Stein, Gary S; Stein, Janet L; Lian, Jane B; Aqeilan, Rami I

    2010-07-01

    The WW domain-containing oxidoreductase (WWOX) is a tumor suppressor that is deleted or attenuated in most human tumors. Wwox-deficient mice develop osteosarcoma (OS), an aggressive bone tumor with poor prognosis that often metastasizes to lung. On the basis of these observations, we examined the status of WWOX in human OS specimens and cell lines. In human OS clinical samples, WWOX expression was absent or reduced in 58% of tumors examined (P < 0.0001). Compared with the primary tumors, WWOX levels frequently increased in tumors resected following chemotherapy. In contrast, tumor metastases to lung often exhibited reduced WWOX levels relative to the primary tumor. In human OS cell lines having reduced WWOX expression, ectopic expression of WWOX inhibited proliferation and attenuated invasion in vitro, and suppressed tumorigenicity in nude mice. Expression of WWOX was associated with reduced RUNX2 expression in OS cell lines, whereas RUNX2 levels were elevated in femurs of Wwox-deficient mice. Furthermore, WWOX reconstitution in HOS cells was associated with downregulation of RUNX2 levels and RUNX2 target genes, consistent with the ability of WWOX to suppress RUNX2 transactivation activity. In clinical samples, RUNX2 was expressed in the majority of primary tumors and undetectable in most tumors resected following chemotherapy, whereas most metastases were RUNX2 positive. Our results deepen the evidence of a tumor suppressor role for WWOX in OS, furthering its prognostic and therapeutic significance in this disease. Copyright 2010 AACR.

  2. Generation and characterization of mice carrying a conditional allele of the Wwox tumor suppressor gene.

    Directory of Open Access Journals (Sweden)

    John H Ludes-Meyers

    Full Text Available WWOX, the gene that spans the second most common human chromosomal fragile site, FRA16D, is inactivated in multiple human cancers and behaves as a suppressor of tumor growth. Since we are interested in understanding WWOX function in both normal and cancer tissues we generated mice harboring a conditional Wwox allele by flanking Exon 1 of the Wwox gene with LoxP sites. Wwox knockout (KO mice were developed by breeding with transgenic mice carrying the Cre-recombinase gene under the control of the adenovirus EIIA promoter. We found that Wwox KO mice suffered from severe metabolic defect(s resulting in growth retardation and all mice died by 3 wk of age. All Wwox KO mice displayed significant hypocapnia suggesting a state of metabolic acidosis. This finding and the known high expression of Wwox in kidney tubules suggest a role for Wwox in acid/base balance. Importantly, Wwox KO mice displayed histopathological and hematological signs of impaired hematopoiesis, leukopenia, and splenic atrophy. Impaired hematopoiesis can also be a contributing factor to metabolic acidosis and death. Hypoglycemia and hypocalcemia was also observed affecting the KO mice. In addition, bone metabolic defects were evident in Wwox KO mice. Bones were smaller and thinner having reduced bone volume as a consequence of a defect in mineralization. No evidence of spontaneous neoplasia was observed in Wwox KO mice. We have generated a new mouse model to inactivate the Wwox tumor suppressor gene conditionally. This will greatly facilitate the functional analysis of Wwox in adult mice and will allow investigating neoplastic transformation in specific target tissues.

  3. Promoter hypermethylation of KLF4 inactivates its tumor suppressor function in cervical carcinogenesis.

    Directory of Open Access Journals (Sweden)

    Wen-Ting Yang

    Full Text Available OBJECTIVE: The KLF4 gene has been shown to be inactivated in cervical carcinogenesis as a tumor suppressor. However, the mechanism of KLF4 silencing in cervical carcinomas has not yet been identified. DNA methylation plays a key role in stable suppression of gene expression. METHODS: The methylation status of the KLF4 promoter CpG islands was analyzed by bisulfite sequencing (BSQ in tissues of normal cervix and cervical cancer. KLF4 gene expression was detected by RT-PCR, immunohistochemistry and western blot. KLF4 promoter methylation in cervical cancer cell line was determined by BSQ and methylation-specific polymerase chain reaction (MS-PCR. Cell proliferation ability was detected by cell growth curve and MTT assay. RESULTS: The methylated allele was found in 41.90% of 24 cervical cancer tissues but only in 11.11% of 11 normal cervix tissues (P<0.005. KLF4 mRNA levels were significantly reduced in cervical cancer tissues compared with normal cervix tissues (P<0.01 and KLF4 mRNA expression showed a significant negative correlation with the promoter hypermethylation (r = -0.486, P = 0.003. Cervical cancer cell lines also showed a significant negative correlation between KLF4 expression and hypermethylation. After treatment with the demethylating agent 5-Azacytidine (5-Aza, the expression of KLF4 in the cervical cancer cell lines at both mRNA and protein levels was drastically increased, the cell proliferation ability was inhibited and the chemosensitivity for cisplatin was significantly increased. CONCLUSION: KLF4 gene is inactivated by methylation-induced silencing mechanisms in a large subset of cervical carcinomas and KLF4 promoter hypermethylation inactivates the gene's function as a tumor suppressor in cervical carcinogenesis.

  4. From tamoxifen to dendrogenin A: The discovery of a mammalian tumor suppressor and cholesterol metabolite.

    Science.gov (United States)

    Silvente-Poirot, Sandrine; de Medina, Philippe; Record, Michel; Poirot, Marc

    2016-11-01

    Tamoxifen (Tam) was developed as a ligand and modulator of estrogen receptor α (ERα) and is one of the main drugs used globally for the hormonotherapy of breast cancers. Besides ERα, Tam also binds with high affinity to the microsomal antiestrogen binding site (AEBS). The AEBS is a hetero-oligomeric proteinaceous complex with cholesterol-5,6-epoxide hydrolase (ChEH) activity that is associated with an intracellular histamine (HA) binding site. The enzymatic activities of the ChEH subunits control developmental programs in mammals and transform cholesterol-5,6-epoxides (5,6-EC) into cholestane-3β,5α,6β-triol. Inhibition of the ChEH activity by pharmacological agents such as Tam induce cancer cell re-differentiation through the accumulation of 5,6-EC. A few years ago, the putative chemical reactivity of the 5,6-EC epoxide group towards nucleophiles led our group to hypothesize that 5,6-EC could react with HA that was co-localized at the AEBS to give a new molecule involved in cell differentiation. This hypothesis was chemically tested and the conjugation of 5,6α-EC: with HA was found possible but only under catalytic conditions. It gave a stereo-selective single product of transformation which was named dendrogenin A (DDA). DDA was found to display potent cancer cell differentiation and anticancer properties in vitro and in vivo, suggesting that it was a tumor suppressor metabolite. The presence of DDA was then established in several mammalian tissues, providing the first evidence of a steroidal alkaloid metabolite in mammals. The discovery of DDA highlights a new metabolic pathway in mammals which lies at the crossroads of cholesterol and histamine metabolism and produces this tumor suppressor metabolite.

  5. Expression of arf tumor suppressor in spermatogonia facilitates meiotic progression in male germ cells.

    Directory of Open Access Journals (Sweden)

    Michelle L Churchman

    2011-07-01

    Full Text Available The mammalian Cdkn2a (Ink4a-Arf locus encodes two tumor suppressor proteins (p16(Ink4a and p19(Arf that respectively enforce the anti-proliferative functions of the retinoblastoma protein (Rb and the p53 transcription factor in response to oncogenic stress. Although p19(Arf is not normally detected in tissues of young adult mice, a notable exception occurs in the male germ line, where Arf is expressed in spermatogonia, but not in meiotic spermatocytes arising from them. Unlike other contexts in which the induction of Arf potently inhibits cell proliferation, expression of p19(Arf in spermatogonia does not interfere with mitotic cell division. Instead, inactivation of Arf triggers germ cell-autonomous, p53-dependent apoptosis of primary spermatocytes in late meiotic prophase, resulting in reduced sperm production. Arf deficiency also causes premature, elevated, and persistent accumulation of the phosphorylated histone variant H2AX, reduces numbers of chromosome-associated complexes of Rad51 and Dmc1 recombinases during meiotic prophase, and yields incompletely synapsed autosomes during pachynema. Inactivation of Ink4a increases the fraction of spermatogonia in S-phase and restores sperm numbers in Ink4a-Arf doubly deficient mice but does not abrogate γ-H2AX accumulation in spermatocytes or p53-dependent apoptosis resulting from Arf inactivation. Thus, as opposed to its canonical role as a tumor suppressor in inducing p53-dependent senescence or apoptosis, Arf expression in spermatogonia instead initiates a salutary feed-forward program that prevents p53-dependent apoptosis, contributing to the survival of meiotic male germ cells.

  6. Enhancement of the RAD51 Recombinase Activity by the Tumor Suppressor PALB2

    Energy Technology Data Exchange (ETDEWEB)

    Dray, Eloise; Etchin, Julia; Wiese, Claudia; Saro, Dorina; Williams, Gareth J.; Hammel, Michal; Yu, Xiong; Galkin, Vitold E.; Liu, Dongqing; Tsai, Miaw-Sheue; Sy, Shirley M-H.; Egelman, Edward; Chen, Junjie; Sung, Patrick; Schild, D.

    2010-08-24

    Homologous recombination mediated by the RAD51 recombinase helps eliminate chromosomal lesions, such as DNA double-stranded breaks induced by radiation or arising from injured DNA replication forks. The tumor suppressors BRCA2 and PALB2 act together to deliver RAD51 to chromosomal lesions to initiate repair. Here we document a new function of PALB2 in the enhancement of RAD51's ability to form the D-loop. We show that PALB2 binds DNA and physically interacts with RAD51. Importantly, while PALB2 alone stimulates D-loop formation, a cooperative effect is seen with RAD51AP1, an enhancer of RAD51. This stimulation stems from PALB2's ability to function with RAD51 and RAD51AP1 to assemble the synaptic complex. Our results help unveil a multi-faceted role of PALB2 in chromosome damage repair. Since PALB2 mutations can cause breast and other tumors or lead to Fanconi anemia, our findings are important for understanding the mechanism of tumor suppression in humans.

  7. Hypermethylation of p16 tumor-suppressor gene in ameloblastic carcinoma, ameloblastoma, and dental follicles.

    Science.gov (United States)

    Khojasteh, Arash; Khodayari, Abbas; Rahimi, Farzaneh; Ghaderian, Mohamad Hossain; Jafarian, Mohamad; Nayebi, Alireza; Akbarzadeh Najar, Reza; Tabatabayipanah, Akram; Jahangirnia, Alireza

    2013-01-01

    The high rate of p16 gene alterations in malignant neoplasms suggests the important effect of this tumor-suppressor gene mutation on the malignant behavior of tumoral lesions. The present study investigated the possible methylation of the p16 tumor in ameloblastic carcinoma, ameloblastoma, and dental follicles. Eighteen samples of ameloblastic carcinoma, ameloblastoma, and dental follicles of mandibular impacted third molar were selected from available documents in the archives of the Department of Oral and Maxillofacial Pathology, Taleghani Hospital and the Department of Oral and Maxillofacial Pathology, Shahid Beheshti University of Medical Sciences, Tehran, Iran. After confirming the initial diagnosis, 6-μm sections were used for DNA extraction. A CpG island methylation of p16 was identified by polymerase chain reaction. Although CpG methylation of p16 was observed in all ameloblastic carcinoma samples, only 1 ameloblastoma specimen exhibited the mutation. The mutation was not detected in other ameloblastoma specimens or in any dental follicle sample. The p16 alteration might play a role in the malignant progression of ameloblastic carcinoma. It is worth mentioning that ameloblastoma can be further differentiated from ameloblastic carcinoma based on molecular observations. Copyright © 2013 American Association of Oral and Maxillofacial Surgeons. Published by Elsevier Inc. All rights reserved.

  8. LARG at chromosome 11q23 has functional characteristics of a tumor suppressor in human breast cancer

    Energy Technology Data Exchange (ETDEWEB)

    Ong, Danny C.T.; Rudduck, Christina; Chin, Koei; Kuo, Wen-Lin; Lie, Daniel K.H.; Chua, Constance L.M.; Wong, Chow Yin; Hong, Ga Sze; Gray, Joe; Lee, Ann S.G.

    2008-05-06

    Deletion of 11q23-q24 is frequent in a diverse variety of malignancies, including breast and colorectal carcinoma, implicating the presence of a tumor suppressor gene at that chromosomal region. We show here that LARG, from 11q23, has functional characteristics of a tumor suppressor. We examined a 6-Mb region on 11q23 by high-resolution deletion mapping, utilizing both loss of heterozygosity (LOH) analysis and microarray comparative genomic hybridization (CGH). LARG (also called ARHGEF12), identified from the analyzed region, was underexpressed in 34% of primary breast carcinomas and 80% of breast cancer cell lines including the MCF-7 line. Multiplex ligation-dependent probe amplification on 30 primary breast cancers and six breast cancer cell lines showed that LARG had the highest frequency of deletion compared to the BCSC-1 and TSLC1 genes, two known candidate tumor suppressor genes from 11q. In vitro analysis of breast cancer cell lines that underexpress LARG showed that LARG could be reactivated by trichostatin A, a histone deacetylase inhibitor, but not by 5-Aza-2{prime}-deoxycytidine, a demethylating agent. Bisulfite sequencing and quantitative high-throughput analysis of DNA methylation confirmed the lack of CpG island methylation in LARG in breast cancer. Restoration of LARG expression in MCF-7 cells by stable transfection resulted in reduced proliferation and colony formation, suggesting that LARG has functional characteristics of a tumor suppressor gene.

  9. von Hippel-Lindau tumor suppressor mutants faithfully model pathological hypoxia-driven angiogenesis and vascular retinopathies in zebrafish

    NARCIS (Netherlands)

    van Rooijen, E.; Voest, E.E.; Logister, I.; Bussmann, J.; Korving, J.; van Eeden, F.J.; Giles, R.H.; Schulte-Merker, S.

    2010-01-01

    Biallelic inactivation of the von Hippel-Lindau (VHL) tumor suppressor gene predisposes human patients to the development of highly vascularized neoplasms in multiple organ systems. We show that zebrafish vhl mutants display a marked increase in blood vessel formation throughout the embryo, starting

  10. A functional dissection of PTEN N-terminus : Implications in PTEN subcellular targeting and tumor suppressor activity

    NARCIS (Netherlands)

    Gil, Anabel; Rodríguez-Escudero, Isabel; Stumpf, Miriam; Molina, María; Cid, Víctor J.; Pulido, Rafael

    2015-01-01

    Spatial regulation of the tumor suppressor PTEN is exerted through alternative plasma membrane, cytoplasmic, and nuclear subcellular locations. The N-terminal region of PTEN is important for the control of PTEN subcellular localization and function. It contains both an active nuclear localization

  11. PCR-RFLP to Detect Codon 248 Mutation in Exon 7 of "p53" Tumor Suppressor Gene

    Science.gov (United States)

    Ouyang, Liming; Ge, Chongtao; Wu, Haizhen; Li, Suxia; Zhang, Huizhan

    2009-01-01

    Individual genome DNA was extracted fast from oral swab and followed up with PCR specific for codon 248 of "p53" tumor suppressor gene. "Msp"I restriction mapping showed the G-C mutation in codon 248, which closely relates to cancer susceptibility. Students learn the concepts, detection techniques, and research significance of point mutations or…

  12. The LKB1 tumor suppressor differentially affects anchorage independent growth of HPV positive cervical cancer cell lines

    Energy Technology Data Exchange (ETDEWEB)

    Mack, Hildegard I.D.; Munger, Karl, E-mail: kmunger@rics.bwh.harvard.edu

    2013-11-15

    Infection with high-risk human papillomaviruses is causally linked to cervical carcinogenesis. However, most lesions caused by high-risk HPV infections do not progress to cancer. Host cell mutations contribute to malignant progression but the molecular nature of such mutations is unknown. Based on a previous study that reported an association between liver kinase B1 (LKB1) tumor suppressor loss and poor outcome in cervical cancer, we sought to determine the molecular basis for this observation. LKB1-negative cervical and lung cancer cells were reconstituted with wild type or kinase defective LKB1 mutants and we examined the importance of LKB1 catalytic activity in known LKB1-regulated processes including inhibition of cell proliferation and elevated resistance to energy stress. Our studies revealed marked differences in the biological activities of two kinase defective LKB1 mutants in the various cell lines. Thus, our results suggest that LKB1 may be a cell-type specific tumor suppressor. - Highlights: • LKB1 is a tumor suppressor that is linked to Peutz-Jeghers syndrome. • Peutz-Jeghers syndrome patients have a high incidence of cervical cancer. • Cervical cancer is caused by HPV infections. • This study investigates LKB1 tumor suppressor activity in cervical cancer.

  13. PCR-RFLP to Detect Codon 248 Mutation in Exon 7 of "p53" Tumor Suppressor Gene

    Science.gov (United States)

    Ouyang, Liming; Ge, Chongtao; Wu, Haizhen; Li, Suxia; Zhang, Huizhan

    2009-01-01

    Individual genome DNA was extracted fast from oral swab and followed up with PCR specific for codon 248 of "p53" tumor suppressor gene. "Msp"I restriction mapping showed the G-C mutation in codon 248, which closely relates to cancer susceptibility. Students learn the concepts, detection techniques, and research significance of point mutations or…

  14. Several noncontiguous domains of CDK4 are involved in binding to the P16 tumor suppressor protein

    NARCIS (Netherlands)

    Ceha, H.M.; Nasser, I.; Medema, R.H.; Slebos, R.J.C.

    1998-01-01

    Cyclin-dependent kinase 4 (CDK4) is a key molecule in the regulation of cell cycle progression at the G1-S phase restriction point. Its activity is specifically regulated by p16 (also known as p16/CDKN2A, p16INK4a, andMTS1), a tumor suppressor frequently altered in human cancers. A specific mutation

  15. Negative regulation of NF-κB by the ING4 tumor suppressor in breast cancer.

    Directory of Open Access Journals (Sweden)

    Sara A Byron

    Full Text Available Nuclear Factor kappa B (NF-κB is a key mediator of normal immune response but contributes to aggressive cancer cell phenotypes when aberrantly activated. Here we present evidence that the Inhibitor of Growth 4 (ING4 tumor suppressor negatively regulates NF-κB in breast cancer. We surveyed primary breast tumor samples for ING4 protein expression using tissue microarrays and a newly generated antibody. We found that 34% of tumors expressed undetectable to low levels of the ING4 protein (n = 227. Tumors with low ING4 expression were frequently large in size, high grade, and lymph node positive, suggesting that down-regulation of ING4 may contribute to breast cancer progression. In the same tumor set, we found that low ING4 expression correlated with high levels of nuclear phosphorylated p65/RelA (p-p65, an activated form of NF-κB (p = 0.018. Fifty seven percent of ING4-low/p-p65-high tumors were lymph node-positive, indicating a high metastatic tendency of these tumors. Conversely, ectopic expression of ING4 inhibited p65/RelA phosphorylation in T47D and MCF7 breast cancer cells. In addition, ING4 suppressed PMA-induced cell invasion and NF-κB-target gene expression in T47D cells, indicating that ING4 inhibited NF-κB activity in breast cancer cells. Supportive of the ING4 function in the regulation of NF-κB-target gene expression, we found that ING4 expression levels inversely correlated with the expression of NF-κB-target genes in primary breast tumors by analyzing public gene expression datasets. Moreover, low ING4 expression or high expression of the gene signature composed of a subset of ING4-repressed NF-κB-target genes was associated with reduced disease-free survival in breast cancer patients. Taken together, we conclude that ING4 negatively regulates NF-κB in breast cancer. Consequently, down-regulation of ING4 leads to activation of NF-κB, contributing to tumor progression and reduced disease-free patient survival in

  16. Genomic annotation of the meningioma tumor suppressor locus on chromosome 1p34.

    Science.gov (United States)

    Sulman, Erik P; White, Peter S; Brodeur, Garrett M

    2004-01-29

    Meningioma is a frequently occurring tumor of the meninges surrounding the central nervous system. Loss of the short arm of chromosome 1 (1p) is the second most frequent chromosomal abnormality observed in these tumors. Previously, we identified a 3.7 megabase (Mb) region of consistent deletion on 1p33-p34 in a panel of 157 tumors. Loss of this region was associated with advanced disease and predictive for tumor relapse. In this report, a high-resolution integrated map of the region was constructed (CompView) to identify all markers in the smallest region of overlapping deletion (SRO). A regional somatic cell hybrid panel was used to more precisely localize those markers identified in CompView as within or overlapping the region. Additional deletion mapping using microsatellites localized to the region narrowed the SRO to approximately 2.8 Mb. The 88 markers remaining in the SRO were used to screen genomic databases to identify large-insert clones. Clones were assembled into a physical map of the region by PCR-based, sequence-tagged site (STS) content mapping. A sequence from clones was used to validate STS content by electronic PCR and to identify transcripts. A minimal tiling path of 43 clones was constructed across the SRO. Sequence data from the most current sequence assembly were used for further validation. A total of 59 genes were ordered within the SRO. In all, 17 of these were selected as likely candidates based on annotation using Gene Ontology Consortium terms, including the MUTYH, PRDX1, FOXD2, FOXE3, PTCH2, and RAD54L genes. This annotation of a putative tumor suppressor locus provides a resource for further analysis of meningioma candidate genes.

  17. Characterization of the novel tumor-suppressor gene CCDC67 in papillary thyroid carcinoma.

    Science.gov (United States)

    Yin, De Tao; Xu, Jianhui; Lei, Mengyuan; Li, Hongqiang; Wang, Yongfei; Liu, Zhen; Zhou, Yubing; Xing, Mingzhao

    2016-02-02

    Some studies showed an association of coiled-coil domain-containing (CCDC) genes with cancers. Our previous limited data specifically suggested a possible pathogenic role of CCDC67 in papillary thyroid cancer (PTC), but this has not been firmly established. The present study was to further investigate and establish this role of CCDC67 in PTC. The expression of CCDC67, both at mRNA and protein levels, was sharply down-regulated in PTC compared with normal thyroid tissues. Lower CCDC67 expression was significantly associated with aggressive tumor behaviors, such as advanced tumor stages and lymph node metastasis, as well as BRAF mutation. Introduced expression of CCDC67 in TPC-1 cells robustly inhibited cell proliferation, colony formation and migration, induced G1 phase cell cycle arrest, and increased cell apoptosis. Primary PTC tumors and matched normal thyroid tissues were obtained from 200 unselected patients at the initial surgery for detection of CCDC67 mRNA and protein by RT-PCR and Western blotting analyses, respectively. Genomic DNA sequencing was performed to detect BRAF mutation in PTC tumors. Clinicopathological data were retrospectively reviewed for correlation analyses. PTC cell line TPC-1 with stable transfection of CCDC67 was used to investigate the functions of CCDC67. This large study demonstrates down-regulation of CCDC67 in PTC, an inverse relationship between CCDC67 expression and PTC aggressiveness and BRAF mutation, and a robust inhibitory effect of CCDC67 on PTC cellular activities. These results are consistent with CCDC67 being a novel and impaired tumor suppressor gene in PTC, providing important prognostic and therapeutic implications for this cancer.

  18. Estrogen receptor β upregulates FOXO3a and causes induction of apoptosis through PUMA in prostate cancer.

    Science.gov (United States)

    Dey, P; Ström, A; Gustafsson, J-Å

    2014-08-14

    Estrogen receptor β (ERβ) is emerging as a critical factor in understanding prostate cancer biology. Although reduced in prostate cancer above Gleason grade 3, ERβ is a potential drug target at the initial stage of the disease. In human prostate cancer cells, we found that ERβ causes apoptosis by increasing the expression of pro-apoptotic factor p53-upregulated modulator of apoptosis (PUMA), independent of p53, but dependent on the forkhead transcription factor class-O family member, FOXO3a. FOXO3a has previously been shown to induce PUMA after growth factor withdrawal and inhibition of the Akt pathway. Surprisingly, the phosphorylation of FOXO3a remained unchanged, while the mRNA and total protein levels of FOXO3a were increased in response to ERβ expression or treatment of PC3, 22Rv1 and LNCaP cells with the ERβ-specific ligands 3β-Adiol (5α-androstane-3β,17β-diol), DPN (diarylpropionitrile) or 8β-VE2 (8-vinylestra-1,3,5 (10)-triene-3,17β-diol). Knockdown of FOXO3a or ERβ expression abolished the increase of PUMA in response to 3β-Adiol in LNCaP and PC3 cells, suggesting that FOXO3a mediates the apoptotic effect of 3β-Adiol-activated ERβ. Moreover, the ventral prostate of ERβ-/- mice had decreased expression of FOXO3a and PUMA compared with the ERβ+/+ mice, indicating a relationship between ERβ and FOXO3a expression. The regulation of FOXO3a by ERβ in normal basal epithelial cells indicates a function of ERβ in cell differentiation and maintenance of cells in a quiescent state. In addition, the expression of ERβ, FOXO3a and PUMA is comparable and higher in benign prostatic hyperplasia than in prostate cancer Gleason grade 4 or higher, where there is substantial loss of ERβ, FOXO3a and PUMA. We conclude that ERβ induces apoptosis of prostate cancer cells by increasing transcription of FOXO3a, leading to an increase of PUMA and subsequent triggering of apoptosis via the intrinsic pathway involving caspase-9. Furthermore, we conclude that

  19. Modification of an apparatus for tumor-suppressor protein crystal growth in the International Space Station

    Science.gov (United States)

    de Morais Mendonca Teles, Antonio

    Some human diseases as tumors are being studied continuously for the development of vaccines against them. And a way of doing that is by means of proteins research. There are some kinds of proteins, like the p53 and p73 proteins, which are tumor suppressors. There are other diseases such as A.I.D.S., hansenosis, the Parkinson's and Chagas' diseases which are protein-related. The determination of how proteins geometrically order themselves, during its biological functions is very necessary to understand how a protein's structure affects its function, to design vaccines that intercede in tumor-protein activities and in other proteins related to those other diseases. The protein crystal growth in microgravity environment produces purer crystallization than on the ground, and it is a powerful tool to produce better vaccines. Several data have already been acquired using ground-based research and in spaceflight experiments aboard the Spacelab and Space Shuttle missions, and in the MIR and in the International Space Station (ISS). Here in this paper, I propose to be performed in the ISS Biological Research Facility (which is being developed), multiple crystal growth of proteins related to cancer (as tumors suppressors and oncoproteins), A.I.D.S., hansenosis, the Parkinson's and Chagas' diseases, for the future obtaining of possible vaccines against them. I also propose a simple and practical equipment, a modification of the crystallization plates (which use a vapor diffusion technique) inside each cylinder of the Protein Crystallization Apparatus in Microgravity (PCAM), with multiple chambers with different sizes. Instead of using some chambers with the same size it is better to use several chambers with different sizes. Why is that? The answer is: the energy associated with the surface tension of the liquid in the chamber is directly related to the circle area of it. So, to minimize the total energy of the surface tension of a proteins liquid -making it more stable

  20. The human LIS1 is downregulated in hepatocellular carcinoma and plays a tumor suppressor function

    Energy Technology Data Exchange (ETDEWEB)

    Xing, Zhen; Tang, Xin; Gao, Yuan; Da, Liang; Song, Hai; Wang, Suiquan [State Key Laboratory of Molecular Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai (China); Tiollais, Pierre [Unite' d' Organisation Nucleaire et Oncogenese, INSERM U.579, Institut Pasteur, Paris (France); Li, Tsaiping [State Key Laboratory of Molecular Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai (China); Zhao, Mujun, E-mail: mjzhao@sibs.ac.cn [State Key Laboratory of Molecular Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai (China)

    2011-06-03

    Highlights: {yields} LIS1 mRNA and protein levels are decreased in 70% HCC tissues. {yields} Downregulation of LIS1 expression induces oncogenic transformation of QSG7701 and NIH3T3 cells in vitro and in vivo. {yields} LIS1 downregulation leads to mitotic errors including spindle and chromosome defects. {yields} Ectopic expression of LIS1 could significantly inhibit HCC cell proliferation and colony formation. {yields} Our results suggest that LIS1 plays a potential tumor suppressor role in the development and progression of HCC. -- Abstract: The human lissencephaly-1 gene (LIS1) is a disease gene responsible for Miller-Dieker lissencephaly syndrome (MDL). LIS1 gene is located in the region of chromosome 17p13.3 that is frequency deleted in MDL patients and in human liver cancer cells. However, the expression and significance of LIS1 in liver cancer remain unknown. Here, we investigated the expression of LIS1 in hepatocellular carcinoma (HCC) tissues by real-time PCR, Western blot, and immunohistochemistry. The results indicated that the mRNA and protein levels of LIS1 were downregulated in about 70% of HCC tissues, and this downregulation was significantly associated with tumor progression. Functional studies showed that the reduction of LIS1 expression in the normal human liver cell line QSG7701 or the mouse fibroblast cell line NIH3T3 by shRNA resulted in colony formation in soft agar and xenograft tumor formation in nude mice, demonstrating that a decrease in the LIS1 level can promote the oncogenic transformation of cells. We also observed that the phenotypes of LIS1-knockdown cells displayed various defective mitotic structures, suggesting that the mechanism by which reduced LIS1 levels results in tumorigenesis is associated with its role in mitosis. Furthermore, we demonstrated that ectopic expression of LIS1 could significantly inhibit HCC cell proliferation and colony formation. Our results suggest that LIS1 plays a potential tumor suppressor role in the

  1. High frequency of loss of allelic integrity at Wilms′ tumor suppressor gene-1 locus in advanced breast tumors associated with aggressiveness of the tumor

    Directory of Open Access Journals (Sweden)

    S Gupta

    2009-01-01

    Full Text Available Background: The product of Wilms′ tumor suppressor gene (WT1, a nuclear transcription factor, regulates the expression of the insulin-like growth factor (IGF and transforming growth factor (TGF systems, both of which are implicated in breast tumorigenesis and are known to facilitate angiogenesis. In the present study, WT1 allelic integrity was examined by Loss of Heterozygosity (LOH studies in infiltrating breast carcinoma (n=60, ductal carcinoma in situ (DCIS (n=10 and benign breast disease (n=5 patients, to determine its possible association with tumor progression. Methods: LOH at the WT1 locus (11p13 as determined by PCR-RFLP for Hinf1 restriction site and was subsequently examined for its association with intratumoral expression of various growth factors i.e. TGF-β1, IGF-II, IGF-1R and angiogenesis (VEGF and Intratumoral micro-vessel density in breast carcinoma. Results: Six of 22 (27.2% genetically heterozygous of infiltrating breast carcinoma and 1 of 4 DCIS cases showed loss of one allele at WT1 locus. Histologically, the tumors with LOH at WT1 were Intraductal carcinoma (IDC and were of grade II and III. There was no correlation in the appearance of LOH at WT1 locus with age, tumor stage, menopausal status, chemotherapy status and lymph node metastasis. The expression of factor IGF-II and its receptor, IGF-1R was significantly higher in carcinoma having LOH at WT1 locus. A positive correlation was observed between the TGF-β1, VEGF expression and IMD scores in infiltrating carcinoma. Conclusions: The current study indicates that the high frequency of loss of allelic integrity at Wilms′ tumor suppressor gene-1 locus in high-graded breast tumors is associated with aggressiveness of the tumor.

  2. Unfurling of the band 4.1, ezrin, radixin, moesin (FERM) domain of the merlin tumor suppressor

    Energy Technology Data Exchange (ETDEWEB)

    Yogesha, S.D.; Sharff, Andrew J.; Giovannini, Marco; Bricogne, Gerard; Izard, Tina (House Ear); (Globel Phasing); (Scripps)

    2014-10-02

    The merlin-1 tumor suppressor is encoded by the Neurofibromatosis-2 (Nf2) gene and loss-of-function Nf2 mutations lead to nervous system tumors in man and to several tumor types in mice. Merlin is an ERM (ezrin, radixin, moesin) family cytoskeletal protein that interacts with other ERM proteins and with components of cell-cell adherens junctions (AJs). Merlin stabilizes the links of AJs to the actin cytoskeleton. Thus, its loss destabilizes AJs, promoting cell migration and invasion, which in Nf2{sup +/-} mice leads to highly metastatic tumors. Paradoxically, the 'closed' conformation of merlin-1, where its N-terminal four-point-one, ezrin, radixin, moesin (FERM) domain binds to its C-terminal tail domain, directs its tumor suppressor functions. Here we report the crystal structure of the human merlin-1 head domain when crystallized in the presence of its tail domain. Remarkably, unlike other ERM head-tail interactions, this structure suggests that binding of the tail provokes dimerization and dynamic movement and unfurling of the F2 motif of the FERM domain. We conclude the 'closed' tumor suppressor conformer of merlin-1 is in fact an 'open' dimer whose functions are disabled by Nf2 mutations that disrupt this architecture.

  3. FoxO3A promotes metabolic adaptation to hypoxia by antagonizing Myc function

    DEFF Research Database (Denmark)

    Jensen, Kim Steen; Binderup, Tina; Jensen, Klaus Thorleif

    2011-01-01

    Exposure of metazoan organisms to hypoxia engages a metabolic switch orchestrated by the hypoxia-inducible factor 1 (HIF-1). HIF-1 mediates induction of glycolysis and active repression of mitochondrial respiration that reduces oxygen consumption and inhibits the production of potentially harmful...... tumour tissue in vivo and that FoxO3A short-hairpin RNA (shRNA)-expressing xenograft tumours are decreased in size and metabolically changed. Our findings define a novel mechanism by which FoxO3A promotes metabolic adaptation and stress resistance in hypoxia.......Exposure of metazoan organisms to hypoxia engages a metabolic switch orchestrated by the hypoxia-inducible factor 1 (HIF-1). HIF-1 mediates induction of glycolysis and active repression of mitochondrial respiration that reduces oxygen consumption and inhibits the production of potentially harmful...

  4. AKT-Foxo3 a信号通路调控小鼠MMP-20基因表达的研究%AKT-Foxo3 a signaling pathway in regulation of MMP-20 gene expression in mouse ameloblasts

    Institute of Scientific and Technical Information of China (English)

    梁广智; 王云虹; 刘媛媛; 慈浩粟; 荣丽; 韩晓谦; 孙轶群; 高玉光

    2014-01-01

    AIM:To investigate the role of AKT-Foxo3a signaling pathway in matrix metalloproteinase-20 (MMP-20)gene expression in mouse ameloblasts.METHODS:AKT-Foxo3a and MMP-20 expression in mouse ameloblasts were examined by immunohistochemistry.Effects of AKT-Foxo3a signaling pathway on MMP-20 promoter were investigated by real-time quantitative RT-PCR and dual luciferase reporter gene assay system.RESULTS:Im-munohistochemical staining results showed that AKT and phosphorylated Foxo3a (P-Foxo3a)were both strongly ex-pressed in the nuclei of secretory ameloblasts.By RT-PCR,it was found that AKT inhibitor reduced the Foxo3a in-duced MMP-20 gene expression (P<0.05).Dual luciferase assay showed that AKT inhibitor decreased MMP-20 pro-moter activity (P<0.05).CONCLUSION:Foxo3a regulates MMP-20 gene expression through AKT-Foxo3a signa-ling pathway in mouse ameloblasts.%目的:本研究旨在探讨AKT-Foxo3a信号通路在基质金属蛋白酶-20(matrix metalloprotein-ase-20,MMP-20)基因表达中的作用。方法:分别通过免疫组化技术、实时定量RT-PCR技术以及双荧光素酶报告基因检测系统分析AKT-Foxo3 a信号通路对MMP-20启动子转录活性的影响。结果:免疫组化染色结果显示,AKT及磷酸化Foxo3 a(P-Foxo3 a)均在分泌期成釉细胞核中呈阳性表达;RT-PCR检测结果显示,AKT阻断剂可显著抑制Foxo3a 诱导的MMP-20基因的表达(P"0.05);双荧光素酶分析结果显示,AKT阻断剂亦可显著抑制Foxo3a调控 MMP-20基因启动子的转录活性(P "0.05)。结论:转录因子 Foxo3a 可能通过AKT-Foxo3 a信号通路调控MMP-20基因的表达,从而参与釉质发育过程。

  5. Association study of FOXO3A SNPs and aging phenotypes in Danish oldest-old individuals.

    Science.gov (United States)

    Soerensen, Mette; Nygaard, Marianne; Dato, Serena; Stevnsner, Tinna; Bohr, Vilhelm A; Christensen, Kaare; Christiansen, Lene

    2015-02-01

    FOXO3A variation has repeatedly been reported to associate with human longevity, yet only few studies have investigated whether FOXO3A variation also associates with aging-related traits. Here, we investigate the association of 15 FOXO3A tagging single nucleotide polymorphisms (SNPs) in 1088 oldest-old Danes (age 92-93) with 4 phenotypes known to predict their survival: cognitive function, hand grip strength, activity of daily living (ADL), and self-rated health. Based on previous studies in humans and foxo animal models, we also explore self-reported diabetes, cancer, cardiovascular disease, osteoporosis, and bone (femur/spine/hip/wrist) fracture. Gene-based testing revealed significant associations of FOXO3A variation with ADL (P = 0.044) and bone fracture (P = 0.006). The single-SNP statistics behind the gene-based analysis indicated increased ADL (decreased disability) and reduced bone fracture risk for carriers of the minor alleles of 8 and 10 SNPs, respectively. These positive directions of effects are in agreement with the positive effects on longevity previously reported for these SNPs. However, when correcting for the test of 9 phenotypes by Bonferroni correction, bone fracture showed borderline significance (P = 0.054), while ADL did not (P = 0.396). Although the single-SNP associations did not formally replicate in another study population of oldest-old Danes (n = 1279, age 94-100), the estimates were of similar direction of effect as observed in the Discovery sample. A pooled analysis of both study populations displayed similar or decreased sized P-values for most associations, hereby supporting the initial findings. Nevertheless, confirmation in additional study populations is needed.

  6. Sirtuin 3 regulates Foxo3a-mediated antioxidant pathway in microglia.

    Science.gov (United States)

    Rangarajan, P; Karthikeyan, A; Lu, J; Ling, E-A; Dheen, S T

    2015-12-17

    Microglia are the prime cellular sources of reactive oxygen species (ROS) in the central nervous system (CNS). Chronic activation of microglia has been linked to aging-associated neurodegenerative diseases such as Alzheimer's disease (AD) and Parkinson's disease (PD) since they produce excessive amounts of ROS for a prolonged duration leading to oxidative stress. The present study was aimed at investigating the expression and role of Sirtuin 3 (Sirt3), a protein deacetylase which is implicated in regulating cellular ROS levels. It has been shown that Sirt3 reduces cellular ROS levels by deacetylating forkhead box O 3a (Foxo3a), a transcription factor which transactivates antioxidant genes, catalase (Cat) and manganese superoxide dismutase (mnSod). In the present study, Sirt3 immunoreactivity was localized in the ameboid microglial cells distributed in the corpus callosum (CC) of the early postnatal rat brain and diminished in the ramified microglial cells in the CC of the adult rat brain. A marked induction of Sirt3 expression was seen in lipopolysaccharide (LPS)-activated microglia in vivo and in vitro as well as in adult rat brains subjected to traumatic brain injury (TBI). Knockdown of Sirt3 in microglia led to an increase in the cellular and mitochondrial ROS and decrease in the expression of antioxidant, mnSod which is indicative of the function of Sirt3 in ROS regulation in microglia. Conversely, Sirt3 overexpression led to increase in the expression of antioxidants Cat and mnSod. Further, increase in the expression and nuclear translocation of Foxo3a was observed following Sirt3 overexpression, suggesting that Sirt3 regulates ROS by inducing the expression of antioxidants via activation of Foxo3a. The above results point to an antioxidant defense mechanism presented by Sirt3 through the activation of Foxo3a, in microglia.

  7. SIRT1-FOXO3a regulate cocaine actions in the nucleus accumbens.

    Science.gov (United States)

    Ferguson, Deveroux; Shao, Ningyi; Heller, Elizabeth; Feng, Jian; Neve, Rachael; Kim, Hee-Dae; Call, Tanessa; Magazu, Samantha; Shen, Li; Nestler, Eric J

    2015-02-18

    Previous studies have shown that chronic cocaine administration induces SIRT1, a Class III histone deacetylase, in the nucleus accumbens (NAc), a key brain reward region, and that such induction influences the gene regulation and place conditioning effects of cocaine. To determine the mechanisms by which SIRT1 mediates cocaine-induced plasticity in NAc, we used chromatin immunoprecipitation followed by massively parallel sequencing (ChIP-seq), 1 d after 7 daily cocaine (20 mg/kg) or saline injections, to map SIRT1 binding genome-wide in mouse NAc. Our unbiased results revealed two modes of SIRT1 action. First, despite its induction in NAc, chronic cocaine causes depletion of SIRT1 from most affected gene promoters in concert with enrichment of H4K16ac (itself a deacetylation target of SIRT1), which is associated with increased expression of these genes. Second, we deduced the forkhead transcription factor (FOXO) family to be a downstream mechanism through which SIRT1 regulates cocaine action. We proceeded to demonstrate that SIRT1 induction causes the deacetylation and activation of FOXO3a in NAc, which leads to the induction of several known FOXO3a gene targets in other systems. Finally, we directly establish a role for FOXO3a in promoting cocaine-elicited behavioral responses by use of viral-mediated gene transfer: we show that overexpressing FOXO3a in NAc enhances cocaine place conditioning. The discovery of these two actions of SIRT1 in NAc in the context of behavioral adaptations to cocaine represents an important step forward in advancing our understanding of the molecular adaptations underlying cocaine action.

  8. Association study of FOXO3ASNPs and aging phenotypes in Danish oldest-old individuals

    Science.gov (United States)

    Soerensen, Mette; Nygaard, Marianne; Dato, Serena; Stevnsner, Tinna; Bohr, Vilhelm A; Christensen, Kaare; Christiansen, Lene

    2015-01-01

    FOXO3Avariation has repeatedly been reported to associate with human longevity, yet only few studies have investigated whether FOXO3Avariation also associates with aging-related traits. Here, we investigate the association of 15 FOXO3Atagging single nucleotide polymorphisms (SNPs) in 1088 oldest-old Danes (age 92–93) with 4 phenotypes known to predict their survival: cognitive function, hand grip strength, activity of daily living (ADL), and self-rated health. Based on previous studies in humans and foxo animal models, we also explore self-reported diabetes, cancer, cardiovascular disease, osteoporosis, and bone (femur/spine/hip/wrist) fracture. Gene-based testing revealed significant associations of FOXO3Avariation with ADL (P = 0.044) and bone fracture (P = 0.006). The single-SNP statistics behind the gene-based analysis indicated increased ADL (decreased disability) and reduced bone fracture risk for carriers of the minor alleles of 8 and 10 SNPs, respectively. These positive directions of effects are in agreement with the positive effects on longevity previously reported for these SNPs. However, when correcting for the test of 9 phenotypes by Bonferroni correction, bone fracture showed borderline significance (P = 0.054), while ADL did not (P = 0.396). Although the single-SNP associations did not formally replicate in another study population of oldest-old Danes (n = 1279, age 94–100), the estimates were of similar direction of effect as observed in the Discovery sample. A pooled analysis of both study populations displayed similar or decreased sized P-values for most associations, hereby supporting the initial findings. Nevertheless, confirmation in additional study populations is needed. PMID:25470651

  9. Regulator of G protein signaling 6 is a novel suppressor of breast tumor initiation and progression.

    Science.gov (United States)

    Maity, Biswanath; Stewart, Adele; O'Malley, Yunxia; Askeland, Ryan W; Sugg, Sonia L; Fisher, Rory A

    2013-08-01

    Breast cancer is a large global health burden and the most frequently diagnosed malignancy in women worldwide. Here, we utilize RGS6(-/-) mice to interrogate the role of regulator of G protein signaling 6 (RGS6), localized to the ductal epithelium in mouse and human breast, as a novel tumor suppressor in vivo. RGS6(-/-) mice exhibit accelerated 7,12-dimethylbenza[α]anthracene (DMBA)-induced tumor initiation and progression, as well as decreased overall survival. Analysis of carcinogenic aberrations in the mammary glands of DMBA-treated mice revealed a failure of the DNA damage response concurrent with augmented oncogenesis in RGS6(-/-) animals. Furthermore, RGS6 suppressed cell growth induced by either human epidermal growth factor receptor 2 or estrogen receptor activation in both MCF-7 breast cancer cells and mammary epithelial cells (MECs). MECs isolated from RGS6(-/-) mice also showed a deficit in DMBA-induced ATM/p53 activation, reactive oxygen species generation and apoptosis confirming that RGS6 is required for effective activation of the DNA damage response in these cells, a critical countermeasure against carcinogen-mediated genotoxic stress. The ability of RGS6 to simultaneously enhance DNA-damage-induced apoptotic signaling and suppress oncogenic cell growth likely underlie the accelerated tumorigenesis and cellular transformation observed in DMBA-treated RGS6(-/-) mice and isolated MECs, respectively. Unsurprisingly, spontaneous tumor formation was also seen in old female RGS6(-/-) but not in wild-type mice. Our finding that RGS6 is downregulated in all human breast cancer subtypes independent of their molecular classification indicates that obtaining a means to restore the growth suppressive and pro-apoptotic actions of RGS6 in breast might be a viable means to treat a large spectrum of breast tumors.

  10. The Drosophila Netrin receptor frazzled/DCC functions as an invasive tumor suppressor

    Directory of Open Access Journals (Sweden)

    Duman-Scheel Molly

    2011-06-01

    Full Text Available Abstract Background Loss of heterozygosity at 18q, which includes the Deleted in Colorectal Cancer (DCC gene, has been linked to many human cancers. However, it is unclear if loss of DCC is the specific underlying cause of these cancers. The Drosophila imaginal discs are excellent systems in which to study DCC function, as it is possible to model human tumors through the generation of somatic clones of cells bearing multiple genetic lesions. Here, these attributes of the fly system were utilized to investigate the potential tumor suppressing functions of the Drosophila DCC homologue frazzled (fra during eye-antennal disc development. Results Most fra loss of function clones are eliminated during development. However, when mutant clone cells generated in the developing eye were rescued from death, partially differentiated eye cells were found outside of the normal eye field, and in extreme cases distant sites of the body. Characterization of these cells during development indicates that fra mutant cells display characteristics of invasive tumor cells, including increased levels of phospho-ERK, phospho-JNK, and Mmp-1, changes in cadherin expression, remodeling of the actin cytoskeleton, and loss of polarity. Mutation of fra promotes basement membrane degradation and invasion which are repressed by inhibition of Rho1 signaling. Although inhibition of JNK signaling blocks invasive phenotypes in some metastatic cancer models in flies, blocking JNK signaling inhibits fra mutant cell death, thereby enhancing the fra mutant phenotype. Conclusions The results of this investigation provide the first direct link between point mutations in fra/DCC and metastatic phenotypes in an animal model and suggest that Fra functions as an invasive tumor suppressor during Drosophila development.

  11. Down-regulation of ECRG4, a candidate tumor suppressor gene, in human breast cancer.

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    Renaud Sabatier

    Full Text Available INTRODUCTION: ECRG4/C2ORF40 is a potential tumor suppressor gene (TSG recently identified in esophageal carcinoma. Its expression, gene copy number and prognostic value have never been explored in breast cancer. METHODS: Using DNA microarray and array-based comparative genomic hybridization (aCGH, we examined ECRG4 mRNA expression and copy number alterations in 353 invasive breast cancer samples and normal breast (NB samples. A meta-analysis was done on a large public retrospective gene expression dataset (n = 1,387 in search of correlations between ECRG4 expression and histo-clinical features including survival. RESULTS: ECRG4 was underexpressed in 94.3% of cancers when compared to NB. aCGH data revealed ECRG4 loss in 18% of tumors, suggesting that DNA loss is not the main mechanism of underexpression. Meta-analysis showed that ECRG4 expression was significantly higher in tumors displaying earlier stage, smaller size, negative axillary lymph node status, lower grade, and normal-like subtype. Higher expression was also associated with disease-free survival (DFS; HR = 0.84 [0.76-0.92], p = 0.0002 and overall survival (OS; HR = 0.72 [0.63-0.83], p = 5.0E-06. In multivariate analysis including the other histo-clinical prognostic features, ECRG4 expression remained the only prognostic factor for DFS and OS. CONCLUSIONS: Our data suggest that ECRG4 is a candidate TSG in breast cancer, the expression of which may help improve the prognostication. If functional analyses confirm this TSG role, restoring ECRG4 expression in the tumor may represent a promising therapeutic approach.

  12. Alternative polyadenylation of tumor suppressor genes in small intestinal neuroendocrine tumors

    DEFF Research Database (Denmark)

    Rehfeld, Anders Aagaard; Plass, Mireya; Døssing, Kristina

    2014-01-01

    The tumorigenesis of small intestinal neuroendocrine tumors (SI-NETs) is poorly understood. Recent studies have associated alternative polyadenylation (APA) with proliferation, cell transformation, and cancer. Polyadenylation is the process in which the pre-messenger RNA is cleaved at a polyA site...... and a polyA tail is added. Genes with two or more polyA sites can undergo APA. This produces two or more distinct mRNA isoforms with different 3' untranslated regions. Additionally, APA can also produce mRNAs containing different 3'-terminal coding regions. Therefore, APA alters both the repertoire...... and the expression level of proteins. Here, we used high-throughput sequencing data to map polyA sites and characterize polyadenylation genome-wide in three SI-NETs and a reference sample. In the tumors, 16 genes showed significant changes of APA pattern, which lead to either the 3' truncation of mRNA coding regions...

  13. PUMA promotes Bax translocation in FOXO3a-dependent pathway during STS-induced apoptosis

    Science.gov (United States)

    Zhang, Yingjie; Chen, Qun

    2009-08-01

    PUMA (p53 up-regulated modulator of apoptosis, also called Bbc3) was first identified as a BH3-only Bcl-2 family protein that is transcriptionally up-regulated by p53 and activated upon p53-dependent apoptotic stimuli, such as treatment with DNA-damaging drugs or UV irradiation. Recently studies have been shown that Puma is also up-regulated in response to certain p53-independent apoptotic stimuli, such as growth factor deprivation or treatment with glucocorticoids or STS (staurosporine). However, the molecular mechanisms of PUMA up-regulation and how PUMA functions in response to p53-independent apoptotic stimuli remain poorly understood. In this study, based on real-time single cell analysis, flow cytometry and western blotting technique, we investigated the function of PUMA in living human lung adenocarcinoma cells (ASTC-a-1) after STS treatment. Our results show that FOXO3a was activated by STS stimulation and then translocated from cytosol to nucleus. The expression of PUMA was up-regulated via a FOXO3a-dependent manner after STS treatment, while p53 had little function in this process. Moreover, cell apoptosis and Bax translocation induced by STS were not blocked by Pifithrin-α (p53 inhibitor), which suggested that p53 was not involved in this signaling pathway. Taken together, these results indicate that PUMA promoted Bax translocation in a FOXO3a-dependment pathway during STS-induced apoptosis, while p53 was dispensable in this process.

  14. FOXO3-mediated up-regulation of Bim contributes to rhein-induced cancer cell apoptosis.

    Science.gov (United States)

    Wang, Jiao; Liu, Shu; Yin, Yancun; Li, Mingjin; Wang, Bo; Yang, Li; Jiang, Yangfu

    2015-03-01

    The anthraquinone compound rhein is a natural agent in the traditional Chinese medicine rhubarb. Preclinical studies demonstrate that rhein has anticancer activity. Treatment of a variety of cancer cells with rhein may induce apoptosis. Here, we report that rhein induces atypical unfolded protein response in breast cancer MCF-7 cells and hepatoma HepG2 cells. Rhein induces CHOP expression, eIF2α phosphorylation and caspase cleavage, while it does not induce glucose-regulated protein 78 (GRP78) expression in both MCF-7 and HepG2 cells. Meanwhile, rhein inhibits thapsigargin-induced GRP78 expression and X box-binding protein 1 splicing. In addition, rhein inhibits Akt phosphorylation and stimulates FOXO transactivation activity. Rhein induces Bim expression in MCF-7 and HepG2 cells, which can be abrogated by FOXO3a knockdown. Knockdown of FOXO3a or Bim abrogates rhein-induced caspase cleavage and apoptosis. The chemical chaperone 4-phenylbutyrate acid antagonizes the induction of FOXO activation, Bim expression and caspase cleavage by rhein, indicating that protein misfolding may be involved in triggering these deleterious effects. We conclude that FOXO3a-mediated up-regulation of Bim is a key mechanism underlying rhein-induced cancer cells apoptosis.

  15. Genistein up-regulates tumor suppressor microRNA-574-3p in prostate cancer.

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    Takeshi Chiyomaru

    Full Text Available Genistein has been shown to inhibit cancers both in vitro and in vivo, by altering the expression of several microRNAs (miRNAs. In this study, we focused on tumor suppressor miRNAs regulated by genistein and investigated their function in prostate cancer (PCa and target pathways. Using miRNA microarray analysis and real-time RT-PCR we observed that miR-574-3p was significantly up-regulated in PCa cells treated with genistein compared with vehicle control. The expression of miR-574-3p was significantly lower in PCa cell lines and clinical PCa tissues compared with normal prostate cells (RWPE-1 and adjacent normal tissues. Low expression level of miR-574-3p was correlated with advanced tumor stage and higher Gleason score in PCa specimens. Re-expression of miR-574-3p in PCa cells significantly inhibited cell proliferation, migration and invasion in vitro and in vivo. miR-574-3p restoration induced apoptosis through reducing Bcl-xL and activating caspase-9 and caspase-3. Using GeneCodis software analysis, several pathways affected by miR-574-3p were identified, such as 'Pathways in cancer', 'Jak-STAT signaling pathway', and 'Wnt signaling pathway'. Luciferase reporter assays demonstrated that miR-574-3p directly binds to the 3' UTR of several target genes (such as RAC1, EGFR and EP300 that are components of 'Pathways in cancer'. Quantitative real-time PCR and Western analysis showed that the mRNA and protein expression levels of the three target genes in PCa cells were markedly down-regulated with miR-574-3p. Loss-of-function studies demonstrated that the three target genes significantly affect cell proliferation, migration and invasion in PCa cell lines. Our results show that genistein up-regulates tumor suppressor miR-574-3p expression targeting several cell signaling pathways. These findings enhance understanding of how genistein regulates with miRNA in PCa.

  16. TIG3 tumor suppressor-dependent organelle redistribution and apoptosis in skin cancer cells.

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    Tiffany M Scharadin

    Full Text Available TIG3 is a tumor suppressor protein that limits keratinocyte survival during normal differentiation. It is also important in cancer, as TIG3 level is reduced in tumors and in skin cancer cell lines, suggesting that loss of expression may be required for cancer cell survival. An important goal is identifying how TIG3 limits cell survival. In the present study we show that TIG3 expression in epidermal squamous cell carcinoma SCC-13 cells reduces cell proliferation and promotes morphological and biochemical apoptosis. To identify the mechanism that drives these changes, we demonstrate that TIG3 localizes near the centrosome and that pericentrosomal accumulation of TIG3 alters microtubule and microfilament organization and organelle distribution. Organelle accumulation at the centrosome is a hallmark of apoptosis and we demonstrate that TIG3 promotes pericentrosomal organelle accumulation. These changes are associated with reduced cyclin D1, cyclin E and cyclin A, and increased p21 level. In addition, Bax level is increased and Bcl-XL level is reduced, and cleavage of procaspase 3, procaspase 9 and PARP is enhanced. We propose that pericentrosomal localization of TIG3 is a key event that results in microtubule and microfilament redistribution and pericentrosomal organelle clustering and that leads to cancer cell apoptosis.

  17. The tumor suppressor, parafibromin, mediates histone H3 K9 methylation for cyclin D1 repression.

    Science.gov (United States)

    Yang, Yong-Jin; Han, Jeung-Whan; Youn, Hong-Duk; Cho, Eun-Jung

    2010-01-01

    Parafibromin, a component of the RNA polymerase II-associated PAF1 complex, is a tumor suppressor linked to hyperparathyroidism-jaw tumor syndrome and sporadic parathyroid carcinoma. Parafibromin induces cell cycle arrest by repressing cyclin D1 via an unknown mechanism. Here, we show that parafibromin interacts with the histone methyltransferase, SUV39H1, and functions as a transcriptional repressor. The central region (128-227 amino acids) of parafibromin is important for both the interaction with SUV39H1 and transcriptional repression. Parafibromin associated with the promoter and coding regions of cyclin D1 and was required for the recruitment of SUV39H1 and the induction of H3 K9 methylation but not H3 K4 methylation. RNA interference analysis showed that SUV39H1 was critical for cyclin D1 repression. These data suggest that parafibromin plays an unexpected role as a repressor in addition to its widely known activity associated with transcriptional activation. Parafibromin as a part of the PAF1 complex might downregulate cyclin D1 expression by integrating repressive H3 K9 methylation during transcription.

  18. Genome-wide DNA methylation indicates silencing of tumor suppressor genes in uterine leiomyoma.

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    Antonia Navarro

    Full Text Available BACKGROUND: Uterine leiomyomas, or fibroids, represent the most common benign tumor of the female reproductive tract. Fibroids become symptomatic in 30% of all women and up to 70% of African American women of reproductive age. Epigenetic dysregulation of individual genes has been demonstrated in leiomyoma cells; however, the in vivo genome-wide distribution of such epigenetic abnormalities remains unknown. PRINCIPAL FINDINGS: We characterized and compared genome-wide DNA methylation and mRNA expression profiles in uterine leiomyoma and matched adjacent normal myometrial tissues from 18 African American women. We found 55 genes with differential promoter methylation and concominant differences in mRNA expression in uterine leiomyoma versus normal myometrium. Eighty percent of the identified genes showed an inverse relationship between DNA methylation status and mRNA expression in uterine leiomyoma tissues, and the majority of genes (62% displayed hypermethylation associated with gene silencing. We selected three genes, the known tumor suppressors KLF11, DLEC1, and KRT19 and verified promoter hypermethylation, mRNA repression and protein expression using bisulfite sequencing, real-time PCR and western blot. Incubation of primary leiomyoma smooth muscle cells with a DNA methyltransferase inhibitor restored KLF11, DLEC1 and KRT19 mRNA levels. CONCLUSIONS: These results suggest a possible functional role of promoter DNA methylation-mediated gene silencing in the pathogenesis of uterine leiomyoma in African American women.

  19. Hsf1 Is Required for the Nuclear Translocation of p53 Tumor Suppressor

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    Qiang Li

    2008-10-01

    Full Text Available Although the p53 tumor suppressor is most frequently inactivated by genetic mutations, exclusion from the nucleus is also seen in human tumors. We have begun to examine p53 nuclear importation by isolating a series of mutant cells in which the temperature-sensitive murine p53Val135 mutant is sequestered in the cytoplasm. We previously showed that that three of them (ALTR12, ALTR19, and ALTR25 constituted a single complementation group. Here, we found that ALTR12 cells are more sensitive to heat stress than either ALTR19 or ALTR25 and that there was a complete lack of induction of Hsp70 in response to heat shock. Western blot analysis showed no expression of the Hsf1 transcription factor, and neither heat shock nor azetidine could induce p53 nuclear localization in ALTR12 cells but did in parental A1–5 cells. Suppression of Hsf1 in A1–5 cells with quercetin or an Hsf1 siRNA reduced p53 nuclear importation and inhibited p53-mediated activation of a p21 reporter. Most convincingly, p53 nuclear importation could be restored in ALTR12 cells by introducing an exogenous Hsf1 gene. Collectively, our result suggests that Hsf1 is required for p53 nuclear importation and activation and implies that heat shock factors play a role in the regulation of p53.

  20. Tumor-suppressor genes, cell cycle regulatory checkpoints, and the skin

    Directory of Open Access Journals (Sweden)

    Ana Maria Abreu Velez

    2015-01-01

    Full Text Available The cell cycle (or cell-division cycle is a series of events that take place in a cell, leading to its division and duplication. Cell division requires cell cycle checkpoints (CPs that are used by the cell to both monitor and regulate the progress of the cell cycle. Tumor-suppressor genes (TSGs or antioncogenes are genes that protect the cell from a single event or multiple events leading to cancer. When these genes mutate, the cell can progress to a cancerous state. We aimed to perform a narrative review, based on evaluation of the manuscripts published in MEDLINE-indexed journals using the Medical Subject Headings (MeSH terms "tumor suppressor′s genes," "skin," and "cell cycle regulatory checkpoints." We aimed to review the current concepts regarding TSGs, CPs, and their association with selected cutaneous diseases. It is important to take into account that in some cell cycle disorders, multiple genetic abnormalities may occur simultaneously. These abnormalities may include intrachromosomal insertions, unbalanced division products, recombinations, reciprocal deletions, and/or duplication of the inserted segments or genes; thus, these presentations usually involve several genes. Due to their complexity, these disorders require specialized expertise for proper diagnosis, counseling, personal and family support, and genetic studies. Alterations in the TSGs or CP regulators may occur in many benign skin proliferative disorders, neoplastic processes, and genodermatoses.

  1. The JNK inhibitor SP600129 enhances apoptosis of HCC cells induced by the tumor suppressor WWOX

    Science.gov (United States)

    Aderca, Ileana; Moser, Catherine D.; Veerasamy, Manivannan; Bani-Hani, Ahmad H.; Bonilla-Guerrero, Ruben; Ahmed, Kadra; Shire, Abdirashid; Cazanave, Sophie C.; Montoya, Damian P.; Mettler, Teresa A.; Burgart, Lawrence J.; Nagorney, David M.; Thibodeau, Stephen N.; Cunningham, Julie M.; Lai, Jin-Ping; Roberts, Lewis R.

    2008-01-01

    Background/Aims The FRA16D fragile site gene WWOX is a tumor suppressor that participates in p53-mediated apoptosis. The c-jun N-terminal kinase JNK1 interacts with WWOX and inhibits apoptosis. We investigated the function of WWOX in human hepatocellular carcinoma (HCC) and the effect of JNK inhibition on WWOX-mediated apoptosis. Methods Allelic imbalance on chromosome 16 was analyzed in 73 HCCs using 53 microsatellite markers. WWOX mRNA in HCC cell lines and primary HCCs was measured by real-time RT-PCR. Effects of WWOX on proliferation and apoptosis and the interaction between WWOX and JNK inhibition were examined. Results Loss on chromosome 16 occurred in 34 of 73 HCCs. Of 11 HCC cell lines, 2 had low, 7 intermediate, and 2 had high WWOX mRNA. Of 51 primary tumors, 23 had low WWOX mRNA. Forced expression of WWOX in SNU387 cells decreased FGF2-mediated proliferation and enhanced apoptosis induced by staurosporine and the JNK inhibitor SP600129. Conversely, knockdown of WWOX in SNU449 cells using shRNA targeting WWOX increased proliferation and resistance to SP600129 induced apoptosis. Conclusions WWOX induces apoptosis and inhibits human HCC cell growth through a mechanism enhanced by JNK inhibition. PMID:18620777

  2. Quantitative analysis of the tumor suppressor dendrogenin A using liquid chromatography tandem mass spectrometry.

    Science.gov (United States)

    Noguer, Emmanuel; Soules, Régis; Netter, Claude; Nagarathinam, Citra; Leignadier, Julie; Huc-Claustre, Emilie; Serhan, Nizar; Rives, Arnaud; de Medina, Philippe; Silvente-Poirot, Sandrine; Poirot, Marc

    2017-07-03

    Dendrogenin A (DDA) was recently identified as a mammalian cholesterol metabolite that displays tumor suppressor and neurostimulating properties at low doses. In breast tumors, DDA levels were found to be decreased compared to normal tissues, evidencing a metabolic deregulation of DDA production in cancers. DDA is an amino-oxysterol that contains three protonatable nitrogen atoms. This makes it physico-chemically different from other oxysterols and it therefore requires specific analytical methods We have previously used a two-step method for the quantification of DDA in biological samples: 1) DDA purification from a Bligh and Dyer extract by RP-HPLC using a 250×4.6mm column, followed by 2) nano-electrospray ionization mass spectrometry (MS) fragmentation to analyze the HPLC fraction of interest. We report here the development a liquid chromatography tandem mass spectrometry method for the analysis of DDA and its analogues. This new method is fast (10min), resolving (peak width <4s) and has a weak carryover (<0.01%). We show that this technique efficiently separates DDA from its C17 isomer and other steroidal alkaloids from the same family establishing a proof of concept for the analysis of this family of amino-oxysterols. Copyright © 2017 Elsevier B.V. All rights reserved.

  3. Does Notch play a tumor suppressor role across diverse squamous cell carcinomas?

    Science.gov (United States)

    Zhang, Min; Biswas, Sangita; Qin, Xin; Gong, Wenrong; Deng, Wenbing; Yu, Hongjun

    2016-08-01

    The role of Notch pathway in tumorigenesis is highly variable. It can be tumor suppressive or pro-oncogenic, typically depending on the cellular context. Squamous cell carcinoma (SCC) is a cancer of the squamous cell, which can occur in diverse human tissues. SCCs are one of the most frequent human malignancies for which the pathologic mechanisms remain elusive. Recent genomic analysis of diverse SCCs identified marked levels of mutations in NOTCH1, implicating Notch signaling pathways in the pathogenesis of SCCs. In this review, evidences highlighting NOTCH's role in different types of SCCs are summarized. Moreover, based on accumulating structural information of the NOTCH receptor, the functional consequences of NOTCH1 gene mutations identified from diverse SCCs are analyzed, emphasizing loss of function of Notch in these cancers. Finally, we discuss the convergent view on an intriguing possibility that Notch may function as tumor suppressor in SCCs across different tissues. These mechanistic insights into Notch signaling pathways will help to guide the research of SCCs and development of therapeutic strategies for these cancers.

  4. The tumor suppressor Caliban regulates DNA damage-induced apoptosis through p53-dependent and -independent activity.

    Science.gov (United States)

    Wang, Y; Wang, Z; Joshi, B H; Puri, R K; Stultz, B; Yuan, Q; Bai, Y; Zhou, P; Yuan, Z; Hursh, D A; Bi, X

    2013-08-15

    We previously identified Caliban (Clbn) as the Drosophila homolog of human Serologically defined colon cancer antigen 1 gene and demonstrated that it could function as a tumor suppressor in human non-small-cell lung cancer (NSCLC) cells, although its mode of action was unknown. Herein, we identify roles for Clbn in DNA damage response. We generate clbn knockout flies using homologous recombination and demonstrate that they have a heightened sensitivity to irradiation. We show that normal Clbn function facilitates both p53-dependent and -independent DNA damage-induced apoptosis. Clbn coordinates different apoptosis pathways, showing a two-stage upregulation following DNA damage. Clbn has proapoptotic functions, working with both caspase and the proapoptotic gene Hid. Finally, ecotopic expression of clbn(+) in NSCLC cells suppresses tumor formation in athymic nude mice. We conclude that Caliban is a regulator of DNA damage-induced apoptosis, functioning as a tumor suppressor in both p53-dependent and -independent pathways.

  5. Identification of Two Candidate Tumor Suppressor Genes on Chromosome l7p13.3: Assessment of their Roles in Breast and Ovarian Carcinogenesis

    Science.gov (United States)

    2000-07-01

    also been reported in primitive neuroectodermal tumors , carcinoma of the cervix uteri, medulloblastoma, osteosarcoma, astrocytoma (22), and acute...AD______ GRANT NUMBER: DAMD17-96-1-6088 TITLE: Identification of Two Candidate Tumor Suppressor Genes on Chromosome 17p13.3: Assessment of their...Identification of Two Candidate Tumor Suppressor Genes on Chromosome 17 p13 .3 : Assessment of their Roles in Breast... DAMD17-96-1-6088 6. AUTHOR(S

  6. Association between FOXO3A gene polymorphisms and human longevity:a meta-analysis

    Institute of Scientific and Technical Information of China (English)

    JiMing Bao; XianLu Song; YingQia Hong; HaiLi Zhu; Cui Li; Tao Zhang; Wei Chen; ShanChao Zhao; Qing Chen

    2014-01-01

    Numerous studies have shown associations between the FOXO3Agene, encoding the forkhead box O3 transcription factor, and human or speciifcally male longevity. However, the associations of speciifc FOXO3A polymorphisms with longevity remain inconclusive. We performed a meta-analysis of existing studies to clarify these potential associations. A comprehensive search was conducted to identify studies of FOXO3A gene polymorphisms and longevity. Pooled odds ratios (ORs) and 95%conifdence intervals (CIs) were calculated by comparing the minor and major alleles. A total of seven articles reporting associations of FOXO3A polymorphisms with longevity were identiifed and included in this meta-analysis. These comprised 11 independent studies with 5241 cases and 5724 controls from different ethnic groups. rs2802292, rs2764264, rs13217795, rs1935949 and rs2802288 polymorphisms were associated with human longevity (OR=1.36, 95%CI=1.10-1.69, P=0.005;OR=1.20, 95%CI=1.04-1.37, P=0.01;OR=1.27, 95%CI=1.10-1.46, P=0.001;OR=1.14, 95%CI=1.01-1.27 and OR=1.24, 95%CI=1.07-1.43, P=0.003, respectively). Analysis stratiifed by gender indicated signiifcant associations between rs2802292, rs2764264 and rs13217795 and male longevity (OR=1.54, 95%CI=1.33-1.79, P<0.001;OR=1.38, 95%CI=1.15-1.66, P=0.001;and OR=1.39, 95%CI=1.15-1.67, P=0.001), but rs2802292, rs2764264 and rs1935949 were not linked to female longevity. Moreover, our study showed no association between rs2153960, rs7762395 or rs13220810 polymorphisms and longevity. In conclusion, this meta-analysis indicates a signiifcant association of ifve FOXO3Agene polymorphisms with longevity, with the effects of rs2802292 and rs2764264 being male-speciifc. Further investigations are required to conifrm these ifndings.

  7. High glucose induced oxidative stress and apoptosis in cardiac microvascular endothelial cells are regulated by FoxO3a.

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    Chaoming Peng

    Full Text Available AIM: Cardiac microvascular endothelial cells (CMECs dysfunction contributes to cardiovascular complications in diabetes, whereas, the underlying mechanism is not fully clarified. FoxO transcription factors are involved in apoptosis and reactive oxygen species (ROS production. Therefore, the present study was designed to elucidate the potential role of FoxO3a on the CMECs injury induced by high glucose. MATERIALS AND METHODS: CMECs were isolated from hearts of adult rats and cultured in normal or high glucose medium for 6 h, 12 h and 24 h respectively. To down-regulate FoxO3a expression, CMECs were transfected with FoxO3a siRNA. ROS accumulation and apoptosis in CMECs were assessed by dihydroethidine (DHE staining and TUNEL assay respectively. Moreover, the expressions of Akt, FoxO3a, Bim and BclxL in CMECs were assessed by Western blotting assay. RESULTS: ROS accumulation in CMECs was significantly increased after high glucose incubation for 6 to 24 h. Meanwhile, high glucose also increased apoptosis in CMECs, correlated with decreased the phosphorylation expressions of Akt and FoxO3a. Moreover, high glucose incubation increased the expression of Bim, whereas increased anti-apoptotic protein BclxL. Furthermore, siRNA target FoxO3a silencing enhanced the ROS accumulation, whereas suppressed apoptosis in CMECs. FoxO3a silencing also abolished the disturbance of Bcl-2 proteins induced by high glucose in CMECs. CONCLUSION: Our data provide evidence that high glucose induced FoxO3a activation which suppressed ROS accumulation, and in parallel, resulted in apoptosis of CMECs.

  8. Epigenetic identification of ZNF545 as a functional tumor suppressor in multiple myeloma via activation of p53 signaling pathway

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    Fan, Yu [Chongqing Key Laboratory of Molecular Oncology and Epigenetics, The First Affiliated Hospital of Chongqing Medical University, Chongqing (China); Zhan, Qian [The Center for Clinical Molecular Medical Detection, The First Affiliated Hospital of Chongqing Medical University, Chongqing (China); Xu, Hongying [Chongqing Key Laboratory of Molecular Oncology and Epigenetics, The First Affiliated Hospital of Chongqing Medical University, Chongqing (China); Li, Lili; Li, Chen [Cancer Epigenetics Laboratory, Department of Clinical Oncology, Sir YK Pao Center for Cancer and Li Ka Shing Institute of Health Sciences, The Chinese University of Hong Kong and CUHK Shenzhen Research Institute (Hong Kong); Xiao, Qian; Xiang, Shili; Hui, Tianli [Chongqing Key Laboratory of Molecular Oncology and Epigenetics, The First Affiliated Hospital of Chongqing Medical University, Chongqing (China); Xiang, Tingxiu, E-mail: larissaxiang@163.com [Chongqing Key Laboratory of Molecular Oncology and Epigenetics, The First Affiliated Hospital of Chongqing Medical University, Chongqing (China); Ren, Guosheng, E-mail: rengs726@126.com [Chongqing Key Laboratory of Molecular Oncology and Epigenetics, The First Affiliated Hospital of Chongqing Medical University, Chongqing (China)

    2016-06-10

    The KRAB–zinc-finger protein ZNF545 was recently identified as a potential suppressor gene in several tumors. However, the regulatory mechanisms of ZNF545 in tumorigenesis remain unclear. In this study, we investigated the expression and roles of ZNF545 in multiple myeloma (MM). ZNF545 was frequently downregulated in MM tissues compared with non-tumor bone marrow tissues. ZNF545 expression was silenced by promoter methylation in MM cell lines, and could be restored by demethylation treatment. ZNF545 methylation was detected in 28.3% of MM tissues, compared with 4.3% of normal bone marrow tissues. ZNF545 transcriptionally activated the p53 signaling pathway but had no effect on Akt in MM, whereas ectopic expression of ZNF545 in silenced cells suppressed their proliferation and induced apoptosis. We therefore identified ZNF545 as a novel tumor suppressor inhibiting tumor growth through activation of the p53 pathway in MM. Moreover, tumor-specific methylation of ZNF545 may represent an epigenetic biomarker for MM diagnosis, and a potential target for specific therapy. -- Highlights: •Downregulated ZNF545 in MM tissues and cell lines and ectopic expression of ZNF545 suppresses tumor growth. •Tumor-specific methylation of ZNF545 represents an epigenetic biomarker for MM diagnosis, and a potential target for specific therapy. •ZNF545 exerts its tumor suppressive effects via transcriptional activating p53 pathway.

  9. Restoration of tumor suppressor miR-34 inhibits human p53-mutant gastric cancer tumorspheres

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    DeSano Jeffrey

    2008-09-01

    Full Text Available Abstract Background MicroRNAs (miRNAs, some of which function as oncogenes or tumor suppressor genes, are involved in carcinogenesis via regulating cell proliferation and/or cell death. MicroRNA miR-34 was recently found to be a direct target of p53, functioning downstream of the p53 pathway as a tumor suppressor. miR-34 targets Notch, HMGA2, and Bcl-2, genes involved in the self-renewal and survival of cancer stem cells. The role of miR-34 in gastric cancer has not been reported previously. In this study, we examined the effects of miR-34 restoration on p53-mutant human gastric cancer cells and potential target gene expression. Methods Human gastric cancer cells were transfected with miR-34 mimics or infected with the lentiviral miR-34-MIF expression system, and validated by miR-34 reporter assay using Bcl-2 3'UTR reporter. Potential target gene expression was assessed by Western blot for proteins, and by quantitative real-time RT-PCR for mRNAs. The effects of miR-34 restoration were assessed by cell growth assay, cell cycle analysis, caspase-3 activation, and cytotoxicity assay, as well as by tumorsphere formation and growth. Results Human gastric cancer Kato III cells with miR-34 restoration reduced the expression of target genes Bcl-2, Notch, and HMGA2. Bcl-2 3'UTR reporter assay showed that the transfected miR-34s were functional and confirmed that Bcl-2 is a direct target of miR-34. Restoration of miR-34 chemosensitized Kato III cells with a high level of Bcl-2, but not MKN-45 cells with a low level of Bcl-2. miR-34 impaired cell growth, accumulated the cells in G1 phase, increased caspase-3 activation, and, more significantly, inhibited tumorsphere formation and growth. Conclusion Our results demonstrate that in p53-deficient human gastric cancer cells, restoration of functional miR-34 inhibits cell growth and induces chemosensitization and apoptosis, indicating that miR-34 may restore p53 function. Restoration of miR-34 inhibits

  10. A phase I study of hydralazine to demethylate and reactivate the expression of tumor suppressor genes

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    Trejo-Becerril Catalina

    2005-04-01

    Full Text Available Abstract Background The antihypertensive compound hydralazine is a known demethylating agent. This phase I study evaluated the tolerability and its effects upon DNA methylation and gene reactivation in patients with untreated cervical cancer. Methods Hydralazine was administered to cohorts of 4 patients at the following dose levels: I 50 mg/day, II 75 mg/day, III 100 mg/day and IV 150 mg/day. Tumor biopsies and peripheral blood samples were taken the day before and after treatment. The genes APC, MGMT; ER, GSTP1, DAPK, RARβ, FHIT and p16 were evaluated pre and post-treatment for DNA promoter methylation and gene expression by MSP (Methylation-Specific PCR and RT-PCR respectively in each of the tumor samples. Methylation of the imprinted H19 gene and the "normally methylated" sequence clone 1.2 was also analyzed. Global DNA methylation was analyzed by capillary electrophoresis and cytosine extension assay. Toxicity was evaluated using the NCI Common Toxicity Criteria. Results Hydralazine was well tolerated. Toxicities were mild being the most common nausea, dizziness, fatigue, headache and palpitations. Overall, 70% of the pretreatment samples and all the patients had at least one methylated gene. Rates of demethylation at the different dose levels were as follows: 50 mg/day, 40%; 75 mg/day, 52%, 100 mg/day, 43%, and 150 mg/day, 32%. Gene expression analysis showed only 12 informative cases, of these 9 (75% re-expressed the gene. There was neither change in the methylation status of H19 and clone 1.2 nor changes in global DNA methylation. Conclusion Hydralazine at doses between 50 and 150 mg/day is well tolerated and effective to demethylate and reactivate the expression of tumor suppressor genes without affecting global DNA methylation

  11. Patterns of somatic uniparental disomy identify novel tumor suppressor genes in colorectal cancer.

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    Torabi, Keyvan; Miró, Rosa; Fernández-Jiménez, Nora; Quintanilla, Isabel; Ramos, Laia; Prat, Esther; del Rey, Javier; Pujol, Núria; Killian, J Keith; Meltzer, Paul S; Fernández, Pedro Luis; Ried, Thomas; Lozano, Juan José; Camps, Jordi; Ponsa, Immaculada

    2015-10-01

    Colorectal cancer (CRC) is characterized by specific patterns of copy number alterations (CNAs), which helped with the identification of driver oncogenes and tumor suppressor genes (TSGs). More recently, the usage of single nucleotide polymorphism arrays provided information of copy number neutral loss of heterozygosity, thus suggesting the occurrence of somatic uniparental disomy (UPD) and uniparental polysomy (UPP) events. The aim of this study is to establish an integrative profiling of recurrent UPDs/UPPs and CNAs in sporadic CRC. Our results indicate that regions showing high frequencies of UPD/UPP mostly coincide with regions typically involved in genomic losses. Among them, chromosome arms 3p, 5q, 9q, 10q, 14q, 17p, 17q, 20p, 21q and 22q preferentially showed UPDs/UPPs over genomic losses suggesting that tumor cells must maintain the disomic state of certain genes to favor cellular fitness. A meta-analysis using over 300 samples from The Cancer Genome Atlas confirmed our findings. Several regions affected by recurrent UPDs/UPPs contain well-known TSGs, as well as novel candidates such as ARID1A, DLC1, TCF7L2 and DMBT1. In addition, VCAN, FLT4, SFRP1 and GAS7 were also frequently involved in regions of UPD/UPP and displayed high levels of methylation. Finally, sequencing and fluorescence in situ hybridization analysis of the gene APC underlined that a somatic UPD event might represent the second hit to achieve biallelic inactivation of this TSG in colorectal tumors. In summary, our data define a profile of somatic UPDs/UPPs in sporadic CRC and highlights the importance of these events as a mechanism to achieve the inactivation of TSGs.

  12. Are there tumor suppressor genes on chromosome 4p in sporadic colorectal carcinoma?

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    Hai-Tao Zheng; Li-Xin Jiang; Zhong-Chuan Lv; Da-Peng Li; Chong-Zhi Zhou; Jian-Jun Gao; Lin He; Zhi-Hai Peng

    2008-01-01

    AIM:To study the candidate tumor suppressor genes (TSG) on chromosome 4p by detecting the high frequency of loss of heterozygosity (LOH) in sporadic colorectal carcinoma in Chinese patients. METHODS: Seven fluorescent labeled polymorphic microsatellite markers were analyzed in 83 cases of colorectal carcinoma and matched normal tissue DNA by PCR. PCR products were eletrophoresed on an ABI 377 DNA sequencer. Genescan 3.7 and Genotype 3.7 software were used for LOH scanning and analysis. The same procedure was performed by the other six microsatellite markers spanning D4S3013 locus to make further detailed deletion mapping. Comparison between LOH frequency and clinicopathological factors was performed by . RESULTS: Data were collected from all informative loci.The average LOH frequency on 4p was 24.25%, and 42.3% and 35.62% on D4S405 and D4S3013 locus, respectively. Adjacent markers of D4S3013 displayed a low LOH frequency (< 30%) by detailed deletion mapping. Significant opposite difference was observed between LOH frequency and tumor diameter on D4S412 and D4S1546 locus (0% vs 16.67%, P = 0.041; 54.55% vs 11.11%, P = 0.034, respectively). On D4S403 locus, LOH was significantly associated with tumor gross pattern (11.11%, 0, 33.33%, P = 0.030). No relationship was detected on other loci compared with clinicopathologial features. CONCLUSION: By deletion mapping, two obvious high frequency LOH regions spanning D4S3013 (4p15.2) and D4S405 (4p14) locus are detected. Candidate TSG, which is involved in carcinogenesis and progression of sporadic colorectal carcinoma on chromosome 4p, may be located between D4S3017 and D4S2933 (about 1.7 cm).

  13. A kinase shRNA screen links LATS2 and the pRB tumor suppressor.

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    Tschöp, Katrin; Conery, Andrew R; Litovchick, Larisa; Decaprio, James A; Settleman, Jeffrey; Harlow, Ed; Dyson, Nicholas

    2011-04-15

    pRB-mediated inhibition of cell proliferation is a complex process that depends on the action of many proteins. However, little is known about the specific pathways that cooperate with the Retinoblastoma protein (pRB) and the variables that influence pRB's ability to arrest tumor cells. Here we describe two shRNA screens that identify kinases that are important for pRB to suppress cell proliferation and pRB-mediated induction of senescence markers. The results reveal an unexpected effect of LATS2, a component of the Hippo pathway, on pRB-induced phenotypes. Partial knockdown of LATS2 strongly suppresses some pRB-induced senescence markers. Further analysis shows that LATS2 cooperates with pRB to promote the silencing of E2F target genes, and that reduced levels of LATS2 lead to defects in the assembly of DREAM (DP, RB [retinoblastoma], E2F, and MuvB) repressor complexes at E2F-regulated promoters. Kinase assays show that LATS2 can phosphorylate DYRK1A, and that it enhances the ability of DYRK1A to phosphorylate the DREAM subunit LIN52. Intriguingly, the LATS2 locus is physically linked with RB1 on 13q, and this region frequently displays loss of heterozygosity in human cancers. Our results reveal a functional connection between the pRB and Hippo tumor suppressor pathways, and suggest that low levels of LATS2 may undermine the ability of pRB to induce a permanent cell cycle arrest in tumor cells.

  14. Identification of LZAP as a new candidate tumor suppressor in hepatocellular carcinoma.

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    Jing-jing Zhao

    Full Text Available BACKGROUND: LZAP was isolated as a binding protein of the Cdk5 activator p35. LZAP has been highly conserved during evolution and has been shown to function as a tumor suppressor in various cancers. This study aimed to investigate LZAP expression and its prognostic value in hepatocellular carcinoma (HCC. Meanwhile, the function of LZAP in hepatocarcinogenesis was further investigated in cell culture models and mouse models. METHODS: Real-time quantitative PCR, western blot and immunohistochemistry were used to explore LZAP expression in HCC cell lines and primary HCC clinical specimens. The functions of LZAP in the proliferation, colony formation, cell cycle, migration, invasion and apoptosis of HCC cell lines were also analyzed by infecting cells with an adenovirus containing full-length LZAP. The effect of LZAP on tumorigenicity in nude mice was also investigated. RESULTS: LZAP expression was significantly decreased in the tumor tissues and HCC cell lines. Clinicopathological analysis showed that LZAP expression was significantly correlated with tumor size, histopathological classification and serum α-fetoprotein (AFP. The Kaplan-Meier survival curves revealed that decreasing LZAP expression was associated with poor prognosis in HCC patients. LZAP expression was an independent prognostic marker of overall HCC patient survival in a multivariate analysis. The re-introduction of LZAP expression in the HepG2 and sk-Hep1 HCC cell lines significantly inhibited proliferation and colony formation in the HCC cells and induced G1 phase arrest and apoptosis of the HCC cells in vitro. Restoring LZAP expression in the HCC cell lines also inhibited migration and invasion. In addition, experiments with a mouse model revealed that LZAP overexpression could suppress HCC tumorigenicity in vivo. CONCLUSIONS: Our data suggest that LZAP may play an important role in HCC progression and could be a potential molecular therapy target for HCC.

  15. Androgen receptor is the key transcriptional mediator of the tumor suppressor SPOP in prostate cancer.

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    Geng, Chuandong; Rajapakshe, Kimal; Shah, Shrijal S; Shou, John; Eedunuri, Vijay Kumar; Foley, Christopher; Fiskus, Warren; Rajendran, Mahitha; Chew, Sue Anne; Zimmermann, Martin; Bond, Richard; He, Bin; Coarfa, Cristian; Mitsiades, Nicholas

    2014-10-01

    Somatic missense mutations in the substrate-binding pocket of the E3 ubiquitin ligase adaptor SPOP are present in up to 15% of human prostate adenocarcinomas, but are rare in other malignancies, suggesting a prostate-specific mechanism of action. SPOP promotes ubiquitination and degradation of several protein substrates, including the androgen receptor (AR) coactivator SRC-3. However, the relative contributions that SPOP substrates may make to the pathophysiology of SPOP-mutant (mt) prostate adenocarcinomas are unknown. Using an unbiased bioinformatics approach, we determined that the gene expression profile of prostate adenocarcinoma cells engineered to express mt-SPOP overlaps greatly with the gene signature of both SRC-3 and AR transcriptional output, with a stronger similarity to AR than SRC-3. This finding suggests that in addition to its SRC-3-mediated effects, SPOP also exerts SRC-3-independent effects that are AR-mediated. Indeed, we found that wild-type (wt) but not prostate adenocarcinoma-associated mutants of SPOP promoted AR ubiquitination and degradation, acting directly through a SPOP-binding motif in the hinge region of AR. In support of these results, tumor xenografts composed of prostate adenocarcinoma cells expressing mt-SPOP exhibited higher AR protein levels and grew faster than tumors composed of prostate adenocarcinoma cells expressing wt-SPOP. Furthermore, genetic ablation of SPOP was sufficient to increase AR protein levels in mouse prostate. Examination of public human prostate adenocarcinoma datasets confirmed a strong link between transcriptomic profiles of mt-SPOP and AR. Overall, our studies highlight the AR axis as the key transcriptional output of SPOP in prostate adenocarcinoma and provide an explanation for the prostate-specific tumor suppressor role of wt-SPOP.

  16. A GATA4-regulated tumor suppressor network represses formation of malignant human astrocytomas

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    Agnihotri, Sameer; Wolf, Amparo; Munoz, Diana M.; Smith, Christopher J.; Gajadhar, Aaron; Restrepo, Andres; Clarke, Ian D.; Fuller, Gregory N.; Kesari, Santosh; Dirks, Peter B.; McGlade, C. Jane; Stanford, William L.; Aldape, Kenneth; Mischel, Paul S.; Hawkins, Cynthia

    2011-01-01

    Glioblastoma Multiforme (GBM), the most common and lethal primary human brain tumor, exhibits multiple molecular aberrations. We report that loss of the transcription factor GATA4, a negative regulator of normal astrocyte proliferation, is a driver in glioma formation and fulfills the hallmarks of a tumor suppressor gene (TSG). Although GATA4 was expressed in normal brain, loss of GATA4 was observed in 94/163 GBM operative samples and was a negative survival prognostic marker. GATA4 loss occurred through promoter hypermethylation or novel somatic mutations. Loss of GATA4 in normal human astrocytes promoted high-grade astrocytoma formation, in cooperation with other relevant genetic alterations such as activated Ras or loss of TP53. Loss of GATA4 with activated Ras in normal astrocytes promoted a progenitor-like phenotype, formation of neurospheres, and the ability to differentiate into astrocytes, neurons, and oligodendrocytes. Re-expression of GATA4 in human GBM cell lines, primary cultures, and brain tumor–initiating cells suppressed tumor growth in vitro and in vivo through direct activation of the cell cycle inhibitor P21CIP1, independent of TP53. Re-expression of GATA4 also conferred sensitivity of GBM cells to temozolomide, a DNA alkylating agent currently used in GBM therapy. This sensitivity was independent of MGMT (O-6-methylguanine-DNA-methyltransferase), the DNA repair enzyme which is often implicated in temozolomide resistance. Instead, GATA4 reduced expression of APNG (alkylpurine-DNA-N-glycosylase), a DNA repair enzyme which is poorly characterized in GBM-mediated temozolomide resistance. Identification and validation of GATA4 as a TSG and its downstream targets in GBM may yield promising novel therapeutic strategies. PMID:21464220

  17. Tumor suppressor roles of CENP-E and Nsl1 in Drosophila epithelial tissues.

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    Clemente-Ruiz, Marta; Muzzopappa, Mariana; Milán, Marco

    2014-01-01

    Depletion of spindle assembly checkpoint (SAC) genes in Drosophila epithelial tissues leads to JNK-dependent programmed cell death and additional blockade of the apoptotic program drives tumorigenesis. A recent report proposes that chromosomal instability (CIN) is not the driving force in the tumorigenic response of the SAC-deficient tissue, and that checkpoint proteins exert a SAC-independent tumor suppressor role. This notion is based on observations that the depletion of CENP-E levels or prevention of Bub3 from binding to the kinetochore in Drosophila tissues unable to activate the apoptotic program induces CIN but does not cause hyperproliferation. Here we re-examined this proposal. In contrast to the previous report, we observed that depletion of CENP-E or Nsl1-the latter mediating kinetochore targeting of Bub3-in epithelial tissues unable to activate the apoptotic program induces significant levels of aneuploidy and drives tumor-like growth. The induction of the JNK transcriptional targets Wingless, a mitogenic molecule, and MMP1, a matrix metaloproteinase 1 involved in basement membrane degradation was also observed in these tumors. An identical response of the tissue was previously detected upon depletion of several SAC genes or genes involved in spindle assembly, chromatin condensation, and cytokinesis, all of which have been described to cause CIN. All together, these results reinforce the role of CIN in driving tumorigenesis in Drosophila epithelial tissues and question the proposed SAC-independent roles of checkpoint proteins in suppressing tumorigenesis. Differences in aneuploidy rates might explain the discrepancy between the previous report and our results.

  18. FOXO3a governs early and late apoptotic endothelial programs during elevated glucose through mitochondrial and caspase signaling.

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    Hou, Jinling; Chong, Zhao Zhong; Shang, Yan Chen; Maiese, Kenneth

    2010-06-10

    Mechanisms that preserve endothelial cell (EC) integrity remain elusive, but are critical for new strategies directed against endocrine disorders such as diabetes mellitus (DM). Here we demonstrate in primary cerebral ECs with a clinically relevant model of elevated d-glucose that Akt1 and the post-translational modification and subcellular trafficking of the forkhead transcription factor FoxO3a are critical for early apoptotic membrane signaling and subsequent degradation of nuclear DNA. FoxO3a also directly governs apoptotic mitochondrial signal transduction pathways, since gene knockdown of FoxO3a prevents mitochondrial membrane depolarization as well as the release of cytochrome c. Control of this apoptotic cascade extends to the rapid and progressive activation of caspases. The presence of FoxO3a is necessary for cleaved (active) caspase 1 and 3 expression, since loss of FoxO3a abrogates the induction of caspase activity. Our work identifies Akt1, FoxO3a and closely aligned pathways as key therapeutic targets during impaired glucose tolerance and DM.

  19. C2-streptavidin mediates the delivery of biotin-conjugated tumor suppressor protein p53 into tumor cells.

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    Fahrer, Jörg; Schweitzer, Brigitte; Fiedler, Katja; Langer, Torben; Gierschik, Peter; Barth, Holger

    2013-04-17

    We have previously generated a recombinant C2-streptavidin fusion protein for the delivery of biotin-labeled molecules of low molecular weight into the cytosol of mammalian cells. A nontoxic moiety of Clostridium botulinum C2 toxin mediates the cellular uptake, whereas the streptavidin unit serves as a binding platform for biotin-labeled cargo molecules. In the present study, we used the C2-streptavidin transporter to introduce biotin-conjugated p53 protein into various mammalian cell lines. The p53 tumor suppressor protein is inactivated in many human cancers by multiple mechanisms and therefore the restoration of its activity in tumor cells is of great therapeutic interest. Recombinant p53 was expressed in insect cells and biotin-labeled. Biotin-p53 retained its specific high-affinity DNA-binding as revealed by gel-shift analysis. Successful conjugation of biotin-p53 to the C2-streptavidin transporter was monitored by an overlay blot technique and confirmed by real-time surface plasmon resonance, providing a KD-value in the low nM range. C2-streptavidin significantly enhanced the uptake of biotin-p53 into African Green Monkey (Vero) epithelial cells as shown by flow cytometry. Using cell fractionation, the cytosolic translocation of biotin-p53 was detected in Vero cells as well as in HeLa cervix carcinoma cells. In line with this finding, confocal microscopy displayed cytoplasmic staining of biotin-p53 in HeLa and HL60 leukemia cells. Internalized biotin-p53 partially colocalized with early endosomes, as confirmed by confocal microscopy. In conclusion, our results demonstrate the successful conjugation of biotin-p53 to C2-streptavidin and its subsequent receptor-mediated endocytosis into different human tumor cell lines.

  20. Malignant Trigeminal Nerve Sheath Tumor and Anaplastic Astrocytoma Collision Tumor with High Proliferative Activity and Tumor Suppressor P53 Expression

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    Maher Kurdi

    2014-01-01

    Full Text Available Background. The synchronous development of two primary brain tumors of distinct cell of origin in close proximity or in contact with each other is extremely rare. We present the first case of collision tumor with two histological distinct tumors. Case Presentation. A 54-year-old woman presented with progressive atypical left facial pain and numbness for 8 months. MRI of the brain showed left middle cranial fossa heterogeneous mass extending into the infratemporal fossa. At surgery, a distinct but intermingled intra- and extradural tumor was demonstrated which was completely removed through left orbitozygomatic-temporal craniotomy. Histopathological examination showed that the tumor had two distinct components: malignant nerve sheath tumor of the trigeminal nerve and temporal lobe anaplastic astrocytoma. Proliferative activity and expressed tumor protein 53 (TP53 gene mutations were demonstrated in both tumors. Conclusions. We describe the first case of malignant trigeminal nerve sheath tumor (MTNST and anaplastic astrocytoma in collision and discuss the possible hypothesis of this rare occurrence. We propose that MTNST, with TP53 mutation, have participated in the formation of anaplastic astrocytoma, or vice versa.

  1. A single-copy Sleeping Beauty transposon mutagenesis screen identifies new PTEN-cooperating tumor suppressor genes.

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    de la Rosa, Jorge; Weber, Julia; Friedrich, Mathias Josef; Li, Yilong; Rad, Lena; Ponstingl, Hannes; Liang, Qi; de Quirós, Sandra Bernaldo; Noorani, Imran; Metzakopian, Emmanouil; Strong, Alexander; Li, Meng Amy; Astudillo, Aurora; Fernández-García, María Teresa; Fernández-García, María Soledad; Hoffman, Gary J; Fuente, Rocío; Vassiliou, George S; Rad, Roland; López-Otín, Carlos; Bradley, Allan; Cadiñanos, Juan

    2017-03-20

    The overwhelming number of genetic alterations identified through cancer genome sequencing requires complementary approaches to interpret their significance and interactions. Here we developed a novel whole-body insertional mutagenesis screen in mice, which was designed for the discovery of Pten-cooperating tumor suppressors. Toward this aim, we coupled mobilization of a single-copy inactivating Sleeping Beauty transposon to Pten disruption within the same genome. The analysis of 278 transposition-induced prostate, breast and skin tumors detected tissue-specific and shared data sets of known and candidate genes involved in cancer. We validated ZBTB20, CELF2, PARD3, AKAP13 and WAC, which were identified by our screens in multiple cancer types, as new tumor suppressor genes in prostate cancer. We demonstrated their synergy with PTEN in preventing invasion in vitro and confirmed their clinical relevance. Further characterization of Wac in vivo showed obligate haploinsufficiency for this gene (which encodes an autophagy-regulating factor) in a Pten-deficient context. Our study identified complex PTEN-cooperating tumor suppressor networks in different cancer types, with potential clinical implications.

  2. Hypermethylation of the tumor suppressor gene PRDM1/Blimp-1 supports a pathogenetic role in EBV-positive Burkitt lymphoma

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    Zhang, T; Ma, J; Nie, K; Yan, J; Liu, Y; Bacchi, C E; Queiroga, E M; Gualco, G; Sample, J T; Orazi, A; Knowles, D M; Tam, W

    2014-01-01

    PRDM1/Blimp-1 is a tumor suppressor gene in the activated B-cell subtype of diffuse large B-cell lymphomas. Its inactivation contributes to pathogenesis in this setting by impairing terminal B-cell differentiation induced by constitutive nuclear factor-κB activation. The role of PRDM1 in Burkitt lymphoma (BL) lymphomagenesis is not known. Here we identified hypermethylation of the promoter region and exon 1 of PRDM1 in all six Epstein–Barr virus (EBV)-positive BL cell lines and 12 of 23 (52%) primary EBV-positive BL or BL-related cases examined, but in none of the EBV-negative BL cell lines or primary tumors that we assessed, implying a tumor suppressor role for PRDM1 specifically in EBV-associated BL. A direct induction of PRDM1 hypermethylation by EBV is unlikely, as PRDM1 hypermethylation was not observed in EBV-immortalized B lymphoblastoid cell lines. Treatment of EBV-positive BL cells with 5′ azacytidine resulted in PRDM1 induction associated with PRDM1 demethylation, consistent with transcriptional silencing of PRDM1 as a result of DNA methylation. Overexpression of PRDM1 in EBV-positive BL cell lines resulted in cell cycle arrest. Our results expand the spectrum of lymphoid malignancies in which PRDM1 may have a tumor suppressor role and identify an epigenetic event that likely contributes to the pathogenesis of BL. PMID:25382611

  3. Lgl2 executes its function as a tumor suppressor by regulating ErbB signaling in the zebrafish epidermis.

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    Sven Reischauer

    2009-11-01

    Full Text Available Changes in tissue homeostasis, acquisition of invasive cell characteristics, and tumor formation can often be linked to the loss of epithelial cell polarity. In carcinogenesis, the grade of neoplasia correlates with impaired cell polarity. In Drosophila, lethal giant larvae (lgl, discs large (dlg, and scribble, which are components of the epithelial apico-basal cell polarity machinery, act as tumor suppressors, and orthologs of this evolutionary conserved pathway are lost in human carcinoma with high frequency. However, a mechanistic link between neoplasia and vertebrate orthologs of these tumor-suppressor genes remains to be fully explored at the organismal level. Here, we show that the pen/lgl2 mutant phenotype shares two key cellular and molecular features of mammalian malignancy: cell autonomous epidermal neoplasia and epithelial-to-mesenchymal-transition (EMT of basal epidermal cells including the differential expression of several regulators of EMT. Further, we found that epidermal neoplasia and EMT in pen/lgl2 mutant epidermal cells is promoted by ErbB signalling, a pathway of high significance in human carcinomas. Intriguingly, EMT in the pen/lgl2 mutant is facilitated specifically by ErbB2 mediated E-cadherin mislocalization and not via canonical snail-dependent down-regulation of E-cadherin expression. Our data reveal that pen/lgl2 functions as a tumor suppressor gene in vertebrates, establishing zebrafish pen/lgl2 mutants as a valuable cancer model.

  4. Identification of myeloid derived suppressor cells in the peripheral blood of tumor bearing dogs

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    Sherger Matthew

    2012-10-01

    Full Text Available Abstract Background Myeloid derived suppressor cells (MDSCs are a recently described population of immune cells that significantly contribute to the immunosuppression seen in cancer patients. MDSCs are one of the most important factors that limit the efficacy of cancer immunotherapy (e.g. cancer vaccines and MDSC levels are increased in cancer in multiple species. Identifying and targeting MDSCs is actively being investigated in the field of human oncology and is increasingly being investigated in veterinary oncology. The treatment of canine cancer not only benefits dogs, but is being used for translational studies evaluating and modifcying candidate therapies for use in humans. Thus, it is necessary to understand the immune alterations seen in canine cancer patients which, to date, have been relatively limited. This study investigates the use of commercially available canine antibodies to detect an immunosuppressive (CD11blow/CADO48low cell population that is increased in the peripheral blood of tumor-bearing dogs. Results Commercially available canine antibodies CD11b and CADO48A were used to evaluate white blood cells from the peripheral blood cells of forty healthy control dogs and forty untreated, tumor-bearing dogs. Tumor-bearing dogs had a statistically significant increase in CD11blow/CADO48Alow cells (7.9% as compared to the control dogs (3.6%. Additionally, sorted CD11blow/CADO48Alow generated in vitro suppressed the proliferation of canine lymphocytes. Conclusions The purpose of this study was aimed at identifying potential canine specific markers for identifying MDSCs in the peripheral blood circulation of dogs. This study demonstrates an increase in a unique CD11blow/CADO48Alow cell population in tumor-bearing dogs. This immunophenotype is consistent with described phenotypes of MDSCs in other species (i.e. mice and utilizes commercially available canine-specific antibodies. Importantly, CD11blow/CADO48Alow from a tumor environment

  5. MicroRNA-34a is a potent tumor suppressor molecule in vivo in neuroblastoma

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    Alcock Leah C

    2011-01-01

    Full Text Available ABSTRACT Background Neuroblastoma is a paediatric cancer which originates from precursor cells of the sympathetic nervous system and accounts for 15% of childhood cancer mortalities. With regards to the role of miRNAs in neuroblastoma, miR-34a, mapping to a chromosome 1p36 region that is commonly deleted, has been found to act as a tumor suppressor through targeting of numerous genes associated with cell proliferation and apoptosis. Methods A synthetic miR-34a (or negative control precursor molecule was transfected into NB1691luc and SK-N-ASluc neuroblastoma cells. Quantitative PCR was used to verify increased miR-34a levels in NB1691luc and SK-N-ASluc cell lines prior to in vitro and in vivo analysis. In vitro analysis of the effects of miR-34a over expression on cell growth, cell cycle and phosphoprotein activation in signal transduction pathways was performed. Neuroblastoma cells over expressing miR-34a were injected retroperitoneally into immunocompromised CB17-SCID mice and tumor burden was assessed over a 21 day period by measuring bioluminescence (photons/sec/cm2. Results Over expression of miR-34a in both NB1691luc and SK-N-ASluc neuroblastoma cell lines led to a significant decrease in cell number relative to premiR-negative control treated cells over a 72 hour period. Flow cytometry results indicated that miR-34a induced cell cycle arrest and subsequent apoptosis activation. Phosphoprotein analysis highlighted key elements involved in signal transduction, whose activation was dysregulated as a result of miR-34a introduction into cells. As a potential mechanism of miR-34a action on phosphoprotein levels, we demonstrate that miR-34a over-expression results in a significant reduction of MAP3K9 mRNA and protein levels. Although MAP3K9 is a predicted target of miR-34a, direct targeting could not be validated with luciferase reporter assays. Despite this fact, any functional effects of reduced MAP3K9 expression as a result of miR-34a would

  6. MicroRNA-34a is a potent tumor suppressor molecule in vivo in neuroblastoma

    LENUS (Irish Health Repository)

    Tivnan, Amanda

    2011-01-25

    ABSTRACT Background Neuroblastoma is a paediatric cancer which originates from precursor cells of the sympathetic nervous system and accounts for 15% of childhood cancer mortalities. With regards to the role of miRNAs in neuroblastoma, miR-34a, mapping to a chromosome 1p36 region that is commonly deleted, has been found to act as a tumor suppressor through targeting of numerous genes associated with cell proliferation and apoptosis. Methods A synthetic miR-34a (or negative control) precursor molecule was transfected into NB1691luc and SK-N-ASluc neuroblastoma cells. Quantitative PCR was used to verify increased miR-34a levels in NB1691luc and SK-N-ASluc cell lines prior to in vitro and in vivo analysis. In vitro analysis of the effects of miR-34a over expression on cell growth, cell cycle and phosphoprotein activation in signal transduction pathways was performed. Neuroblastoma cells over expressing miR-34a were injected retroperitoneally into immunocompromised CB17-SCID mice and tumor burden was assessed over a 21 day period by measuring bioluminescence (photons\\/sec\\/cm2). Results Over expression of miR-34a in both NB1691luc and SK-N-ASluc neuroblastoma cell lines led to a significant decrease in cell number relative to premiR-negative control treated cells over a 72 hour period. Flow cytometry results indicated that miR-34a induced cell cycle arrest and subsequent apoptosis activation. Phosphoprotein analysis highlighted key elements involved in signal transduction, whose activation was dysregulated as a result of miR-34a introduction into cells. As a potential mechanism of miR-34a action on phosphoprotein levels, we demonstrate that miR-34a over-expression results in a significant reduction of MAP3K9 mRNA and protein levels. Although MAP3K9 is a predicted target of miR-34a, direct targeting could not be validated with luciferase reporter assays. Despite this fact, any functional effects of reduced MAP3K9 expression as a result of miR-34a would be expected to

  7. Role of human papillomavirus and tumor suppressor genes in oral cancer.

    Science.gov (United States)

    Manvikar, Vardendra; Kulkarni, Rama; Koneru, Anila; Vanishree, M

    2016-01-01

    The incidence of oral cancer remains high and is associated with many deaths in both Western and Asian countries. Several risk factors for the development of oral cancer are now well known, including smoking, drinking and consumption of smokeless tobacco products. Genetic predisposition to oral cancer has been found in certain cases, but its components are not yet entirely clear. In accordance with the multi-step theory of carcinogenesis, the natural history of oral cancer seems to gradually evolve through transitional precursor lesions from normal epithelium to a full-blown metastatic phenotype. A number of genomic lesions accompany this transformation and a wealth of related results has appeared in recent literature and is being summarized here. Furthermore, several key genes have been implicated, especially well-known tumor suppressors such as the cyclin-dependent kinase inhibitors, TP53 and RB1 and oncogenes such as the cyclin family, epidermal growth factor receptor and RAS. Viral infections, particularly oncogenic human papillomavirus subtypes and Epstein-Barr virus, can have a tumorigenic effect on oral epithelia and their role is discussed, along with potential therapeutic interventions. A brief explanatory theoretical model of oral carcinogenesis is provided and potential avenues for further research are highlighted.

  8. Role of human papillomavirus and tumor suppressor genes in oral cancer

    Directory of Open Access Journals (Sweden)

    Vardendra Manvikar

    2016-01-01

    Full Text Available The incidence of oral cancer remains high and is associated with many deaths in both Western and Asian countries. Several risk factors for the development of oral cancer are now well known, including smoking, drinking and consumption of smokeless tobacco products. Genetic predisposition to oral cancer has been found in certain cases, but its components are not yet entirely clear. In accordance with the multi-step theory of carcinogenesis, the natural history of oral cancer seems to gradually evolve through transitional precursor lesions from normal epithelium to a full-blown metastatic phenotype. A number of genomic lesions accompany this transformation and a wealth of related results has appeared in recent literature and is being summarized here. Furthermore, several key genes have been implicated, especially well-known tumor suppressors such as the cyclin-dependent kinase inhibitors, TP53 and RB1 and oncogenes such as the cyclin family, epidermal growth factor receptor and RAS. Viral infections, particularly oncogenic human papillomavirus subtypes and Epstein-Barr virus, can have a tumorigenic effect on oral epithelia and their role is discussed, along with potential therapeutic interventions. A brief explanatory theoretical model of oral carcinogenesis is provided and potential avenues for further research are highlighted.

  9. [Hypermethylation and downregulation of tumor suppressor gene p16 in benzene poisoning].

    Science.gov (United States)

    Xing, Caihong; Wang, Qianfei; Tian, Haoyuan; Li, Bin; Ni, Yune; Yin, Songnian; Guo, Xinbiao; Li, Guilan

    2012-03-01

    To investigate whether benzene negatively affects the expression of p16 through DNA methylation. We carried out a case-control study in Chinese occupational benzene poisoning patients. Eleven cases of BP and 8 controls who were matched for age (+/- 5 years), sex, working duration and job title with BP were recruited. Expression level was examined by quantitative real-time PCR. Bisulfite-PCR pyrosequencing was used to quantitate the level of DNA methylation. The expression levels of p16 are down-regulated in BP patients compared to the control group (0.53 versus 2.06, P = 0.064). The average percentage of methylated cytosines of p16 was higher in BP group than in controls (12.4%, 11.3%, respectively, P > 0.05). p16 mRNA level decreased with increasing methylation (Pearson r = -0.64, P > 0.05). The fourth CpG site in p16 promoter is located within the consensus binding sequence for olfactory neuron-specific transcription factor. A significant negative correlation between mRNA level and the fourth CpG site was exhibited (Pearson r = - 0.88, P p16 is significantly downregulated in BP patients. Hypermethylation in promoter CpG islands is likely to contribute to the downregulation of p16. Further in-depth studies, utilizing large number of samples, are needed to fully understand the molecular mechanism involved in the tumor-suppressor gene inactivation in benzene-related diseases.

  10. Interferon-Inducible Protein 16: Insight into the Interaction with Tumor Suppressor p53

    Energy Technology Data Exchange (ETDEWEB)

    Liao, Jack C.C.; Lam, Robert; Brazda, Vaclav; Duan, Shili; Ravichandran, Mani; Ma, Justin; Xiao, Ting; Tempel, Wolfram; Zuo, Xiaobing; Wang, Yun-Xing; Chirgadze, Nickolay Y.; Arrowsmith, Cheryl H. (Toronto); (NCI)

    2011-08-24

    IFI16 is a member of the interferon-inducible HIN-200 family of nuclear proteins. It has been implicated in transcriptional regulation by modulating protein-protein interactions with p53 tumor suppressor protein and other transcription factors. However, the mechanisms of interaction remain unknown. Here, we report the crystal structures of both HIN-A and HIN-B domains of IFI16 determined at 2.0 and 2.35 {angstrom} resolution, respectively. Each HIN domain comprises a pair of tightly packed OB-fold subdomains that appear to act as a single unit. We show that both HIN domains of IFI16 are capable of enhancing p53-DNA complex formation and transcriptional activation via distinctive means. HIN-A domain binds to the basic C terminus of p53, whereas the HIN-B domain binds to the core DNA-binding region of p53. Both interactions are compatible with the DNA-bound state of p53 and together contribute to the effect of full-length IFI16 on p53-DNA complex formation and transcriptional activation.

  11. The tumor suppressor Nf2 regulates corpus callosum development by inhibiting the transcriptional coactivator Yap.

    Science.gov (United States)

    Lavado, Alfonso; Ware, Michelle; Paré, Joshua; Cao, Xinwei

    2014-11-01

    The corpus callosum connects cerebral hemispheres and is the largest axon tract in the mammalian brain. Callosal malformations are among the most common congenital brain anomalies and are associated with a wide range of neuropsychological deficits. Crossing of the midline by callosal axons relies on a proper midline environment that harbors guidepost cells emitting guidance cues to instruct callosal axon navigation. Little is known about what controls the formation of the midline environment. We find that two components of the Hippo pathway, the tumor suppressor Nf2 (Merlin) and the transcriptional coactivator Yap (Yap1), regulate guidepost development and expression of the guidance cue Slit2 in mouse. During normal brain development, Nf2 suppresses Yap activity in neural progenitor cells to promote guidepost cell differentiation and prevent ectopic Slit2 expression. Loss of Nf2 causes malformation of midline guideposts and Slit2 upregulation, resulting in callosal agenesis. Slit2 heterozygosity and Yap deletion both restore callosal formation in Nf2 mutants. Furthermore, selectively elevating Yap activity in midline neural progenitors is sufficient to disrupt guidepost formation, upregulate Slit2 and prevent midline crossing. The Hippo pathway is known for its role in controlling organ growth and tumorigenesis. Our study identifies a novel role of this pathway in axon guidance. Moreover, by linking axon pathfinding and neural progenitor behaviors, our results provide an example of the intricate coordination between growth and wiring during brain development.

  12. The tumor suppressor gene retinoblastoma-1 is required for retinotectal development and visual function in zebrafish.

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    Michael Gyda

    Full Text Available Mutations in the retinoblastoma tumor suppressor gene (rb1 cause both sporadic and familial forms of childhood retinoblastoma. Despite its clinical relevance, the roles of rb1 during normal retinotectal development and function are not well understood. We have identified mutations in the zebrafish space cadet locus that lead to a premature truncation of the rb1 gene, identical to known mutations in sporadic and familial forms of retinoblastoma. In wild-type embryos, axons of early born retinal ganglion cells (RGC pioneer the retinotectal tract to guide later born RGC axons. In rb1 deficient embryos, these early born RGCs show a delay in cell cycle exit, causing a transient deficit of differentiated RGCs. As a result, later born mutant RGC axons initially fail to exit the retina, resulting in optic nerve hypoplasia. A significant fraction of mutant RGC axons eventually exit the retina, but then frequently project to the incorrect optic tectum. Although rb1 mutants eventually establish basic retinotectal connectivity, behavioral analysis reveals that mutants exhibit deficits in distinct, visually guided behaviors. Thus, our analysis of zebrafish rb1 mutants reveals a previously unknown yet critical role for rb1 during retinotectal tract development and visual function.

  13. In vitro binding properties of tumor suppressor p53 with PUMA and NOXA.

    Science.gov (United States)

    Park, So Young; Jeong, Mi Suk; Jang, Se Bok

    2012-04-06

    The p53-upregulated modulator of apoptosis (Puma) and Noxa, are direct targets in p53-mediated apoptosis localized to the mitochondria. Tumor suppressor p53 induces apoptosis by transcriptional induction of Puma and Noxa, which encode proapoptotic BH3-only member Bcl-1 family proteins. However, at a molecular level, the mechanism of action of Puma and Noxa proteins remain poorly defined. In addition, there have been no reports on whether or not p53 directly interacts with Puma and Noxa, in vitro. Here, we provide evidence indicating that the DNA binding domain (DBD) of p53 directly interacted with the BH3 domains of human PUMA and NOXA. Our studies revealed that PUMA has a weak affinity for p53, but NOXA has significant affinity for p53. In this study, we developed a molecular docking model using homology modeling based on the structures of truncated p53, PUMA and NOXA. In addition, we investigated whether or not six mutants of p53 (K101A, T102A, L111A, D186A, G199A and S227A) were able to bind to PUMA and NOXA. Four structure-based mutations (T102A, L111A, D186A and G199A) disrupted the p53-PUMA/NOXA interaction. Our study suggested that these four mutations lowered the stability of the p53 DBD domain and induced aggregation of structurally destabilized p53, and thus disrupted the p53-PUMA/NOXA interaction.

  14. THE TMEFF2 TUMOR SUPPRESSOR MODULATES INTEGRIN EXPRESSION, RHOA ACTIVATION AND MIGRATION OF PROSTATE CANCER CELLS

    Science.gov (United States)

    Chen, Xiaofei; Corbin, Joshua M.; Tipton, Greg J.; Yang, Li V.; Asch, Adam S.; Ruiz-Echevarría, Maria J.

    2014-01-01

    Cell adhesion and migration play important roles in physiological and pathological states, including embryonic development and cancer invasion and metastasis. The type I transmembrane protein with epidermal growth factor and two follistatin motifs 2 (TMEFF2) is expressed mainly in brain and prostate and its expression is deregulated in prostate cancer. We have previously shown that TMEFF2 can function as a tumor suppressor by inhibiting cell migration and invasion of prostate cells. However, the molecular mechanisms involved in this inhibition are not clear. In this study we demonstrate that TMEFF2 affects cell adhesion and migration of prostate cancer cells and that this effect correlates with changes in integrin expression and RhoA activation. Deletion of a 13 basic-rich amino acid region in the cytoplasmic domain of TMEFF2 prevented these effects. Overexpression of TMEFF2 reduced cell attachment and migration on vitronectin and caused a concomitant decrease in RhoA activation, stress fiber formation and expression of αv, β1 and β3 integrin subunits. Conversely, TMEFF2 interference in 22Rv1 prostate cancer cells resulted in increased integrin expression. Results obtained with a double TRAMP/TMEFF2 transgenic mouse also indicated that TMEFF2 expression reduced integrin expression in the mouse prostate. In summary, the data presented here indicate an important role of TMEFF2 in regulating cell adhesion and migration that involves integrin signaling and is mediated by its cytoplasmic domain. PMID:24632071

  15. The tumor suppressor role of miR-124 in osteosarcoma.

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    Shuo Geng

    Full Text Available MicroRNAs have crucial roles in development and progression of human cancers, including osteosarcoma. Recent studies have shown that miR-124 was down-regulated in many cancers; however, the role of miR-124 in osteosarcoma development is unknown. In this study, we demonstrate that expression of miR-124 is significantly downregulated in osteosarcoma tissues and cell lines, compared to the adjacent tissues. The expression of miR-124 in the metastases osteosarcoma tissues was lower than that in non- metastases tissues. We identified and confirmed Rac1 as a novel, direct target of miR-124 using prediction algorithms and luciferase reporter gene assays. Overexpression of miR-124 suppressed Rac1 protein expression and attenuated cell proliferation, migration, and invasion and induced apoptosis in MG-63 and U2OS in vitro. Moreover, overexpression of Rac1 in miR-124-transfected osteosarcoma cells effectively rescued the inhibition of cell invasion caused by miR-124. Therefore, our results demonstrate that miR-124 is a tumor suppressor miRNA and suggest that this miRNA could be a potential target for the treatment of osteosarcoma in future.

  16. ARF functions as a melanoma tumor suppressor by inducing p53-independent senescence

    Science.gov (United States)

    Ha, Linan; Ichikawa, Takeshi; Anver, Miriam; Dickins, Ross; Lowe, Scott; Sharpless, Norman E.; Krimpenfort, Paul; DePinho, Ronald A.; Bennett, Dorothy C.; Sviderskaya, Elena V.; Merlino, Glenn

    2007-01-01

    Inactivation of the p53 pathway represents the most common molecular defect of human cancer. But in the setting of melanoma, a highly aggressive and invariably fatal malignancy in its advanced disseminated form, mutation/deletion of p53 is relatively rare, whereas its positive regulator ARF is often lost. Here, we show that genetic deficiency in Arf but not p53 facilitates rapid development of melanoma in a genetically engineered mouse model. This difference is accounted for, at least in part, by the unanticipated observation that, unlike fibroblasts, senescence control in melanocytes is strongly regulated by Arf and not p53. Moreover, oncogenic NRAS collaborates with deficiency in Arf, but not p53, to fully transform melanocytes. Our data demonstrate that ARF and p53, although linked in a common pathway, suppress tumorigenesis through distinct, lineage-dependent mechanisms and suggest that ARF helps restrict melanoma progression by executing the oncogene-induced senescence program in benign nevi. Thus, therapeutics designed to restore wild-type p53 function may be insufficient to counter melanoma and other malignancies in which ARF holds p53-independent tumor suppressor activity. PMID:17576930

  17. Delocalization and destabilization of the Arf tumor suppressor by the leukemia-associated NPM mutant.

    Science.gov (United States)

    Colombo, Emanuela; Martinelli, Paola; Zamponi, Raffaella; Shing, Danielle C; Bonetti, Paola; Luzi, Lucilla; Volorio, Sara; Bernard, Loris; Pruneri, Giancarlo; Alcalay, Myriam; Pelicci, Pier Giuseppe

    2006-03-15

    One third of acute myeloid leukemias (AMLs) are characterized by the aberrant cytoplasmic localization of nucleophosmin (NPM) due to mutations within its putative nucleolar localization signal. NPM mutations are mutually exclusive with major AML-associated chromosome rearrangements and are frequently associated with a normal karyotype, suggesting that they are critical during leukemogenesis. The underlying molecular mechanisms are, however, unknown. NPM is a nucleocytoplasmic shuttling protein that has been implicated in several cellular processes, including ribosome biogenesis, centrosome duplication, cell cycle progression, and stress response. It has been recently shown that NPM is required for the stabilization and proper nucleolar localization of the tumor suppressor p19(Arf). We report here that the AML-associated NPM mutant localizes mainly in the cytoplasm due to an alteration of its nucleus-cytoplasmic shuttling equilibrium, forms a direct complex with p19(Arf), but is unable to protect it from degradation. Consequently, cells or leukemic blasts expressing the NPM mutant have low levels of cytoplasmic Arf. Furthermore, we show that expression of the NPM mutant reduces the ability of Arf to initiate a p53 response and to induce cell cycle arrest. Inactivation of p19(Arf), a key regulator of the p53-dependent cellular response to oncogene expression, might therefore contribute to leukemogenesis in AMLs with mutated NPM.

  18. Isolation of a rice gene homologous to the human putative tumor suppressor gene QM

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    QM gene was originally isolated from human by Dowdy et al during a search for a wilms′ tumor suppressor gene. Researches of QM gene focused mainly on animals and yeasts, little was known about plant QM gene. For better understanding of QM gene in rice, a QM homologous fragment was used as a probe to screen rice (Oryza sativa subsp. indica c.v. Guanglu′ ai 4) genomic DNA library,and two clones were obtained. One of them, OSQM2, encoded a highly basic protein of 184 amino acids, the sequence was about 3.1 kb long with a very special promoter region compared with other known QM genes. Seven potential G boxes could be found between -690 and -230. G box, which contains a ACGT core motif, had been reported in many plants to act as a cis acting DNA element in the regulation of genes in a variety of environmental conditions, such as ABA regulated gene expression, red light, UV light, anaerobiosis, and wounding etc. Two closely linked DRE related motifs (dehydration responsive element) could also be found between -182 and 173, which had a CCGAC conserved sequence and had been identified in many cold and drought responsive genes in Arabidopsis. Six MYC recognition sequences with the conserved motif NCANNTGN were also presented, which might be essential for ABA and drought responsive expression of the plant genes.

  19. SUSD2 is frequently downregulated and functions as a tumor suppressor in RCC and lung cancer.

    Science.gov (United States)

    Cheng, Yingying; Wang, Xiaolin; Wang, Pingzhang; Li, Ting; Hu, Fengzhan; Liu, Qiang; Yang, Fan; Wang, Jun; Xu, Tao; Han, Wenling

    2016-07-01

    Sushi domain containing 2 (SUSD2) is type I membrane protein containing domains inherent to adhesion molecules. There have been few reported studies on SUSD2, and they have mainly focused on breast cancer, colon cancer, and HeLa cells. However, the expression and function of SUSD2 in other cancers remain unclear. In the present study, we conducted an integrated bioinformatics analysis based on the array data from the GEO database and found a significant downregulation of SUSD2 in renal cell carcinoma (RCC) and lung cancer. Western blotting and quantitative RT-PCR (qRT-PCR) confirmed that SUSD2 was frequently decreased in RCC and lung cancer tissues compared with the corresponding levels in normal adjacent tissues. The restoration of SUSD2 expression inhibited the proliferation and clonogenicity of RCC and lung cancer cells, whereas the knockdown of SUSD2 promoted A549 cell growth. Our findings suggested that SUSD2 functions as a tumor suppressor gene (TSG) in RCC and lung cancer.

  20. Genomic characterization of Wilms' tumor suppressor 1 targets in nephron progenitor cells during kidney development.

    Science.gov (United States)

    Hartwig, Sunny; Ho, Jacqueline; Pandey, Priyanka; Macisaac, Kenzie; Taglienti, Mary; Xiang, Michael; Alterovitz, Gil; Ramoni, Marco; Fraenkel, Ernest; Kreidberg, Jordan A

    2010-04-01

    The Wilms' tumor suppressor 1 (WT1) gene encodes a DNA- and RNA-binding protein that plays an essential role in nephron progenitor differentiation during renal development. To identify WT1 target genes that might regulate nephron progenitor differentiation in vivo, we performed chromatin immunoprecipitation (ChIP) coupled to mouse promoter microarray (ChIP-chip) using chromatin prepared from embryonic mouse kidney tissue. We identified 1663 genes bound by WT1, 86% of which contain a previously identified, conserved, high-affinity WT1 binding site. To investigate functional interactions between WT1 and candidate target genes in nephron progenitors, we used a novel, modified WT1 morpholino loss-of-function model in embryonic mouse kidney explants to knock down WT1 expression in nephron progenitors ex vivo. Low doses of WT1 morpholino resulted in reduced WT1 target gene expression specifically in nephron progenitors, whereas high doses of WT1 morpholino arrested kidney explant development and were associated with increased nephron progenitor cell apoptosis, reminiscent of the phenotype observed in Wt1(-/-) embryos. Collectively, our results provide a comprehensive description of endogenous WT1 target genes in nephron progenitor cells in vivo, as well as insights into the transcriptional signaling networks controlled by WT1 that might direct nephron progenitor fate during renal development.

  1. MicroRNA-125b Functions as a Tumor Suppressor in Hepatocellular Carcinoma Cells

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    Hao-Liang Zhao

    2012-07-01

    Full Text Available MicroRNAs (miRNAs are important regulators of multiple cellular processes, and the deregulation of miRNA is a common event in diverse human diseases, particularly cancer. However, the mechanisms underlying the relationship between disordered miRNA expression and tumorigenesis have remained largely unknown. In this study, we demonstrated the down-regulation of miR-125b in hepatocellular carcinoma (HCC tissues and HCC cell lines by Northern blot and quantitative RT-PCR analyses. The ectopic expression of miR-125b reduced the cellular proliferation and cell cycle progression of HCC cells by targeting Mcl-1 and IL6R. Furthermore, the miR-125b-induced inhibition of cell proliferation was rescued by the expression of Mcl-1 or IL6R variants that lacked 3' UTRs. Thus, this study revealed the differential expression of miR-125b in HCC cells and elucidated its potential as a tumor suppressor in HCC development.

  2. CHROMOSOME 3 MAY HARBOR MULTIPLE TUMOR SUPPRESSOR GENES ASSOCIATED WITH PRIMARY GLIOBLASTOMA MULTIFORME

    Institute of Scientific and Technical Information of China (English)

    胡杰; 江澄川; 吴浩强; 彭颂先; 唐婉君; 陈商群

    2002-01-01

    Objective: To investigate whether deletion of chromosome 3 is involved in the carcinogenesis of primary glioblastoma multiforme (GBM) and to localize the possible common deletion region in the aforementioned chromosome. Methods: PCR based microsatellite polymorphism analyses were performed to detect loss of heterozygosity (LOH). Twenty-three loci on chromosome 3 were examined in 20 cases of GBM. Fluorescence-labeled primers and Perkin Elmer 377 DNA Sequencer were applied. Results: 50% informative cases of GBM displayed LOH on chromosome 3. 50% of informative cases displayed LOH on 3q and 35% on 3p. 25.6% of informative loci showed LOH in our series, in which frequent LOH were observed in the chromosomal region from loci D3S1614 (42.9%) to D3S1565 (35.3%) on 3q24(27 and at loci D3S1569 (35.3%) on 3q22(23 and D3S1289 (33.3%) on 3p14.1(14.3. Conclusion: Loss of genetic material on chromosome 3 may play an important part in the tumorigenesis of GBM. The chromosomal regions from loci D3S1614 to D3S1565 on 3q24(27 and at loci D3S1569 on 3q22(23 and D3S1289 on 3p14.1(14.3 are potential sites for novel tumor suppressor genes associated with GBM.

  3. Tumor suppressor protein C53 antagonizes checkpoint kinases to promote cyclin-dependent kinase 1 activation.

    Science.gov (United States)

    Jiang, Hai; Wu, Jianchun; He, Chen; Yang, Wending; Li, Honglin

    2009-04-01

    Cyclin-dependent kinase 1 (Cdk1)/cyclin B1 complex is the driving force for mitotic entry, and its activation is tightly regulated by the G2/M checkpoint. We originally reported that a novel protein C53 (also known as Cdk5rap3 and LZAP) potentiates DNA damage-induced cell death by modulating the G2/M checkpoint. More recently, Wang et al. (2007) found that C53/LZAP may function as a tumor suppressor by way of inhibiting NF-kappaB signaling. We report here the identification of C53 protein as a novel regulator of Cdk1 activation. We found that knockdown of C53 protein causes delayed Cdk1 activation and mitotic entry. During DNA damage response, activation of checkpoint kinase 1 and 2 (Chk1 and Chk2) is partially inhibited by C53 overexpression. Intriguingly, we found that C53 interacts with Chk1 and antagonizes its function. Moreover, a portion of C53 protein is localized at the centrosome, and centrosome-targeting C53 potently promotes local Cdk1 activation. Taken together, our results strongly suggest that C53 is a novel negative regulator of checkpoint response. By counteracting Chk1, C53 promotes Cdk1 activation and mitotic entry in both unperturbed cell-cycle progression and DNA damage response.

  4. Tumor suppressor protein C53 antagonizes checkpoint kinases to promote cyclin-dependent kinase 1 activation

    Institute of Scientific and Technical Information of China (English)

    Hai Jiang; Jianchun Wu; Chen He; Wending Yang; Honglin Li

    2009-01-01

    Cyclin-dependent kinase 1 (Cdk1)/cyclin B1 complex is the driving force for mitotic entry, and its activation is tightly regulated by the G2/M checkpoint. We originally reported that a novel protein C53 (also known as Cdk5rap3 and LZAP) potentiates DNA damage-induced cell death by modulating the G2/M checkpoint. More recently, Wang et al. (2007) found that C53/LZAP may function as a tumor suppressor by way of inhibiting NF-kB signaling. We report here the identification of C53 protein as a novel regulator of Cdk1 activation. We found that knockdown of C53 protein causes delayed Cdkl activation and mitotic entry. During DNA damage response, activation of checkpoint kinase 1 and 2 (Chk1 and Chk2) is partially inhibited by C53 overexpression. Intriguingly, we found that C53 interacts with Chkl and antagonizes its function. Moreover, a portion of C53 protein is localized at the centrosome, and centrosome-targeting C53 potently promotes local Cdk1 activation. Taken together, our results strongly suggest that C53 is a novel negative regulator of checkpoint response. By counteracting Chk1, C53 promotes Cdk1 activation and mitotic entry in both unperturbed cell-cycle progression and DNA damage response.

  5. Inactivation of tumor suppressor genes and cancer therapy: An evolutionary game theory approach.

    Science.gov (United States)

    Khadem, Heydar; Kebriaei, Hamed; Veisi, Zahra

    2017-03-06

    Inactivation of alleles in tumor suppressor genes (TSG) is one of the important issues resulting in evolution of cancerous cells. In this paper, the evolution of healthy, one and two missed allele cells is modeled using the concept of evolutionary game theory and replicator dynamics. The proposed model also takes into account the interaction rates of the cells as designing parameters of the system. Different combinations of the equilibrium points of the parameterized nonlinear system is studied and categorized into some cases. In each case, the interaction rates' values are suggested in a way that the equilibrium points of the replicator dynamics are located on an appropriate region of the state space. Based on the suggested interaction rates, it is proved that the system doesn't have any undesirable interior equilibrium point as well. Therefore, the system will converge to the desirable region, where there is a scanty level of cancerous cells. In addition, the proposed conditions for interaction rates guarantee that, when a trajectory of the system reaches the boundaries, then it will stay there forever which is a desirable property since the equilibrium points have been already located on the boundaries, appropriately. The simulation results show the effectiveness of the suggestions in the elimination of the cancerous cells in different scenarios.

  6. In vivo functional analysis of the human NF2 tumor suppressor gene in Drosophila.

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    Heather S Gavilan

    Full Text Available The proper control of tissue growth is essential during normal development and an important problem in human disease. Merlin, the product of the Neurofibromatosis 2 tumor suppressor gene, has been extensively studied to understand its functions in growth control. Here we describe experiments in which we used Drosophila as an in vivo system to test the functions of the normal human NF2 gene products and patient-derived mutant alleles. Although the predominant NF2 gene isoform, isoform 1, could functionally replace the Drosophila Merlin gene, a second isoform with a distinct C-terminal tail could not. Immunofluorescence studies show that the two isoforms have distinct subcellular localizations when expressed in the polarized imaginal epithelium, and function in genetic rescue assays correlates with apical localization of the NF2 protein. Interestingly, we found that a patient-derived missense allele, NF2L64P, appears to be temperature sensitive. These studies highlight the utility of Drosophila for in vivo functional analysis of highly conserved human disease genes.

  7. Targeting Calcium Signaling Induces Epigenetic Reactivation of Tumor Suppressor Genes in Cancer.

    Science.gov (United States)

    Raynal, Noël J-M; Lee, Justin T; Wang, Youjun; Beaudry, Annie; Madireddi, Priyanka; Garriga, Judith; Malouf, Gabriel G; Dumont, Sarah; Dettman, Elisha J; Gharibyan, Vazganush; Ahmed, Saira; Chung, Woonbok; Childers, Wayne E; Abou-Gharbia, Magid; Henry, Ryan A; Andrews, Andrew J; Jelinek, Jaroslav; Cui, Ying; Baylin, Stephen B; Gill, Donald L; Issa, Jean-Pierre J

    2016-03-15

    Targeting epigenetic pathways is a promising approach for cancer therapy. Here, we report on the unexpected finding that targeting calcium signaling can reverse epigenetic silencing of tumor suppressor genes (TSG). In a screen for drugs that reactivate silenced gene expression in colon cancer cells, we found three classical epigenetic targeted drugs (DNA methylation and histone deacetylase inhibitors) and 11 other drugs that induced methylated and silenced CpG island promoters driving a reporter gene (GFP) as well as endogenous TSGs in multiple cancer cell lines. These newly identified drugs, most prominently cardiac glycosides, did not change DNA methylation locally or histone modifications globally. Instead, all 11 drugs altered calcium signaling and triggered calcium-calmodulin kinase (CamK) activity, leading to MeCP2 nuclear exclusion. Blocking CamK activity abolished gene reactivation and cancer cell killing by these drugs, showing that triggering calcium fluxes is an essential component of their epigenetic mechanism of action. Our data identify calcium signaling as a new pathway that can be targeted to reactivate TSGs in cancer.

  8. Regulatory roles of tumor-suppressor proteins and noncoding RNA in cancer and normal cell functions.

    Science.gov (United States)

    Garen, Alan; Song, Xu

    2008-04-15

    We describe a mechanism for reversible regulation of gene transcription, mediated by a family of tumor-suppressor proteins (TSP) containing a DNA-binding domain (DBD) that binds to a gene and represses transcription, and RNA-binding domains (RBDs) that bind RNA, usually a noncoding RNA (ncRNA), forming a TSP/RNA complex that releases the TSP from a gene and reverses repression. This mechanism appears to be involved in the regulation of embryogenesis, oncogenesis, and steroidogenesis. Embryonic cells express high levels of RNA that bind to a TSP and prevent repression of proto-oncogenes that drive cell proliferation. The level of the RNA subsequently decreases in most differentiating cells, enabling a TSP to repress proto-oncogenes and stop cell proliferation. Oncogenesis can result when the level of the RNA fails to decrease in a proliferating cell or increases in a differentiated cell. This mechanism also regulates transcription of P450scc, the first gene in the steroidogenic pathway.

  9. Self-association of the WT1 tumor suppressor gene product

    Energy Technology Data Exchange (ETDEWEB)

    Bruening, W.; Nakagama, H.: Bardessy, N. [McGill Univ., Montreal (Canada)] [and others

    1994-09-01

    Wilms` tumor (WT), an embryonal malignancy of the kidney, occurs most frequently in children under the age of 5 years, affecting {approximately}1 in 10,000 individuals. The WT1 tumor suppressor gene, residing at 11p13, is structurally altered in {approximately}10-15% of WT cases. Individuals with germline mutations within the WT1 gene suffer from predisposition to WT and developmental defects of the urogenital system. Patients with heterozygous deletions of the WT1 gene, or mutations predicted to cause inactivation of one WT1 allele, suffer relatively mild genital system defects (notably hypospadias and cryptorchidism in males) and a predisposition to WT. These results suggest that developing genital system development is sensitive to the absolute concentrations of the WT1 gene products. Patients with missense mutations within the WT1 gene, however, can suffer from a much more severe disorder known as Denys-Drash syndrome (DDS). This syndrome is characterized by intersex disorders, renal nephropathy, and a predisposition to WTs. The increased severity of the developmental defects associated with DDS, compared to those individuals with mild genital system anomalies and WTs, suggests that mutations defined in patients with DDS behave in a dominant-negative fashion. We have identified a novel WT1 mutation in a patient with DDS. This mutation, predicted to produce a truncated WT1 polypeptide encompassing exons 1, 2, and 3, defines a domain capable of behaving as an antimorph. We have also demonstrated that WT1 can self-associate in vivo using yeast two-hybrid systems. Deletion analysis have mapped the interacting domains to the amino terminus of the WT1 polypeptide, within exons 1 and 2. These results provide a molecular mechanism to explain how WT1 mutations can function in a dominant-negative fashion to eliminate wild-type WT1 activity, leading to DDS.

  10. 15-Lipoxygenase-1 Activates Tumor Suppressor p53 Independent of Enzymatic Activity

    Science.gov (United States)

    Zhu, Hong; Glasgow, Wayne; George, Margaret D.; Chrysovergis, Kali; Olden, Kenneth; Roberts, John D.; Eling, Thomas

    2008-01-01

    15-LOX-1 and its metabolites are involved in colorectal cancer. Recently, we reported that 15-LOX-1 overexpression in HCT-116 human colorectal cancer cells inhibited cell growth by induction of p53 phosphorylation (4). To determine whether the 15-LOX-1 protein or its metabolites are responsible for phosphorylation of p53 in HCT-116 cells, we used HCT-116 cells that expressed a mutant 15-LOX-1. The mutant 15-LOX-1 enzyme, with a substitution of Leu at residue His361, was devoid of enzymatic activity. HCT-116 cells transiently transfected with either native or mutant 15-LOX-1 showed an increase in p53 phosphorylation and an increase in the expression of downstream genes. Thus 15-LOX-1 induces p53 phosphorylation independent of enzymatic activity. Treatment of A549 human lung carcinoma cells with IL-4 increased the expression of 15-LOX-1 and also increased the expression of downstream targets of p53. This confirmed that the activation of p53 was also observed in wild type cells expressing physiological 15-LOX-1. Immunoprecipitation experiments revealed that 15-LOX-1 interacts with, and binds to, DNA-dependent protein kinase (DNA-PK). The binding of 15-LOX-1 to DNA-PK caused an approximate 3.0 fold enhancement in kinase activity, resulting in increased p53 phosphorylation at Ser15. Knockdown of DNA-PK by small interfering RNA (siRNA) significantly reduced p53 phosphorylation. Furthermore, confocal microscopy demonstrated a co-localization of 15-LOX and DNA-PK in the cells. We propose that the 15-LOX-1 protein binds to DNA-PK, increasing its kinase activity, and results in downstream activation of the tumor suppressor p53, thus revealing a new mechanism by which lipoxygenases may influence the phenotype of tumor cells. PMID:18785202

  11. Context-dependent activation of Wnt signaling by tumor suppressor RUNX3 in gastric cancer cells

    Science.gov (United States)

    Ju, Xiaoli; Ishikawa, Tomo-o; Naka, Kazuhito; Ito, Kosei; Ito, Yoshiaki; Oshima, Masanobu

    2014-01-01

    RUNX3 is a tumor suppressor for a variety of cancers. RUNX3 suppresses the canonical Wnt signaling pathway by binding to the TCF4/β-catenin complex, resulting in the inhibition of binding of the complex to the Wnt target gene promoter. Here, we confirmed that RUNX3 suppressed Wnt signaling activity in several gastric cancer cell lines; however, we found that RUNX3 increased the Wnt signaling activity in KatoIII and SNU668 gastric cancer cells. Notably, RUNX3 expression increased the ratio of the Wnt signaling-high population in the KatoIII cells. although the maximum Wnt activation level of individual cells was similar to that in the control. As found previously, RUNX3 also binds to TCF4 and β-catenin in KatoIII cells, suggesting that these molecules form a ternary complex. Moreover, the ChIP analyses revealed that TCF4, β-catenin and RUNX3 bind the promoter region of the Wnt target genes, Axin2 and c-Myc, and the occupancy of TCF4 and β-catenin in these promoter regions is increased by the RUNX3 expression. These results suggest that RUNX3 stabilizes the TCF4/β-catenin complex on the Wnt target gene promoter in KatoIII cells, leading to activation of Wnt signaling. Although RUNX3 increased the Wnt signaling activity, its expression resulted in suppression of tumorigenesis of KatoIII cells, indicating that RUNX3 plays a tumor-suppressing role in KatoIII cells through a Wnt-independent mechanism. These results indicate that RUNX3 can either suppress or activate the Wnt signaling pathway through its binding to the TCF4/β-catenin complex by cell context-dependent mechanisms. PMID:24447505

  12. ERK5/BMK1 is a novel target of the tumor suppressor VHL: Implication in clear cell renal carcinoma

    OpenAIRE

    Arias-González, Laura; Moreno-Gimeno, Inmaculada; del Campo, Antonio Rubio; Leticia, Serrano-Oviedo; Valero, María Llanos; Esparís-Ogando, Azucena; de la Cruz-Morcillo, Miguel Ángel; Melgar-Rojas, Pedro; García-Cano, Jesús; Cimas, Francisco José; Hidalgo, María José Ruiz; Prado, Alfonso; Callejas-Valera, Juan Luis; Nam-Cha, Syong Hyun; Giménez-Bachs, José Miguel

    2013-01-01

    Extracellular signal-regulated kinase 5 (ERK5), also known as big mitogen-activated protein kinase (MAPK) 1, is implicated in a wide range of biologic processes, which include proliferation or vascularization. Here, we show that ERK5 is degraded through the ubiquitin-proteasome system, in a process mediated by the tumor suppressor von Hippel-Lindau (VHL) gene, through a prolyl hydroxylation-dependent mechanism. Our conclusions derive from transient transfection assays in Cos7 cells, as well a...

  13. ERK5/BMK1 Is a Novel Target of the Tumor Suppressor VHL: Implication in Clear Cell Renal Carcinoma12

    OpenAIRE

    Arias-González, Laura; Moreno-Gimeno, Inmaculada; del Campo, Antonio Rubio; Serrano-Oviedo, Leticia; Valero, María Llanos; Esparís-Ogando, Azucena; de la Cruz-Morcillo, Miguel Ángel; Melgar-Rojas, Pedro; García-Cano, Jesús; Cimas, Francisco José; Hidalgo, María José Ruiz; Prado, Alfonso; Callejas-Valera, Juan Luis; Nam-Cha, Syong Hyun; Giménez-Bachs, José Miguel

    2013-01-01

    Extracellular signal-regulated kinase 5 (ERK5), also known as big mitogen-activated protein kinase (MAPK) 1, is implicated in a wide range of biologic processes, which include proliferation or vascularization. Here, we show that ERK5 is degraded through the ubiquitin-proteasome system, in a process mediated by the tumor suppressor von Hippel-Lindau (VHL) gene, through a prolyl hydroxylation-dependent mechanism. Our conclusions derive from transient transfection assays in Cos7 cells, as well a...

  14. Altered Ca(2+) signaling in cancer cells: proto-oncogenes and tumor suppressors targeting IP3 receptors.

    Science.gov (United States)

    Akl, Haidar; Bultynck, Geert

    2013-04-01

    Proto-oncogenes and tumor suppressors critically control cell-fate decisions like cell survival, adaptation and death. These processes are regulated by Ca(2+) signals arising from the endoplasmic reticulum, which at distinct sites is in close proximity to the mitochondria. These organelles are linked by different mechanisms, including Ca(2+)-transport mechanisms involving the inositol 1,4,5-trisphosphate receptor (IP3R) and the voltage-dependent anion channel (VDAC). The amount of Ca(2+) transfer from the endoplasmic reticulum to mitochondria determines the susceptibility of cells to apoptotic stimuli. Suppressing the transfer of Ca(2+) from the endoplasmic reticulum to the mitochondria increases the apoptotic resistance of cells and may decrease the cellular responsiveness to apoptotic signaling in response to cellular damage or alterations. This can result in the survival, growth and proliferation of cells with oncogenic features. Clearly, proper maintenance of endoplasmic reticulum Ca(2+) homeostasis and dynamics including its links with the mitochondrial network is essential to detect and eliminate altered cells with oncogenic features through the apoptotic pathway. Proto-oncogenes and tumor suppressors exploit the central role of Ca(2+) signaling by targeting the IP3R. There are an increasing number of reports showing that activation of proto-oncogenes or inactivation of tumor suppressors directly affects IP3R function and endoplasmic reticulum Ca(2+) homeostasis, thereby decreasing mitochondrial Ca(2+) uptake and mitochondrial outer membrane permeabilization. In this review, we provide an overview of the current knowledge on the proto-oncogenes and tumor suppressors identified as IP3R-regulatory proteins and how they affect endoplasmic reticulum Ca(2+) homeostasis and dynamics.

  15. Loss of the tumor suppressor LKB1 promotes metabolic reprogramming of cancer cells via HIF-1α.

    Science.gov (United States)

    Faubert, Brandon; Vincent, Emma E; Griss, Takla; Samborska, Bozena; Izreig, Said; Svensson, Robert U; Mamer, Orval A; Avizonis, Daina; Shackelford, David B; Shaw, Reuben J; Jones, Russell G

    2014-02-18

    One of the major metabolic changes associated with cellular transformation is enhanced nutrient utilization, which supports tumor progression by fueling both energy production and providing biosynthetic intermediates for growth. The liver kinase B1 (LKB1) is a serine/threonine kinase and tumor suppressor that couples bioenergetics to cell-growth control through regulation of mammalian target of rapamycin (mTOR) activity; however, the influence of LKB1 on tumor metabolism is not well defined. Here, we show that loss of LKB1 induces a progrowth metabolic program in proliferating cells. Cells lacking LKB1 display increased glucose and glutamine uptake and utilization, which support both cellular ATP levels and increased macromolecular biosynthesis. This LKB1-dependent reprogramming of cell metabolism is dependent on the hypoxia-inducible factor-1α (HIF-1α), which accumulates under normoxia in LKB1-deficient cells and is antagonized by inhibition of mTOR complex I signaling. Silencing HIF-1α reverses the metabolic advantages conferred by reduced LKB1 signaling and impairs the growth and survival of LKB1-deficient tumor cells under low-nutrient conditions. Together, our data implicate the tumor suppressor LKB1 as a central regulator of tumor metabolism and growth control through the regulation of HIF-1α-dependent metabolic reprogramming.

  16. Functional interactions between Lmo2, the Arf tumor suppressor, and Notch1 in murine T-cell malignancies.

    Science.gov (United States)

    Treanor, Louise M; Volanakis, Emmanuel J; Zhou, Sheng; Lu, Taihe; Sherr, Charles J; Sorrentino, Brian P

    2011-05-19

    LMO2 is a target of chromosomal translocations in T-cell tumors and was activated by retroviral vector insertions in T-cell tumors from X-SCID patients in gene therapy trials. To better understand the cooperating genetic events in LMO2-associated T-cell acute lymphoblastic leukemia (T-ALL), we investigated the roles of Arf tumor suppressor loss and Notch activation in murine models of transplantation. Lmo2 overexpression enhanced the expansion of primitive DN2 thymocytes, eventually facilitating the stochastic induction of clonal CD4(+)/CD8(+) malignancies. Inactivation of the Arf tumor suppressor further increased the self-renewal capacity of the primitive, preleukemic thymocyte pool and accelerated the development of aggressive, Lmo2-induced T-cell lympholeukemias. Notch mutations were frequently detected in these Lmo2-induced tumors. The Arf promoter was not directly engaged by Lmo2 or mutant Notch, and use of a mouse model in which activation of a mutant Notch allele depends on previous engagement of the Arf promoter revealed that Notch activation could occur as a subsequent event in T-cell tumorigenesis. Therefore, Lmo2 cooperates with Arf loss to enhance self-renewal in primitive thymocytes. Notch mutation and Arf inactivation appear to independently cooperate in no requisite order with Lmo2 overexpression in inducing T-ALL, and all 3 events remained insufficient to guarantee immediate tumor development.

  17. Protein tyrosine phosphatase receptor delta acts as a neuroblastoma tumor suppressor by destabilizing the aurora kinase a oncogene

    LENUS (Irish Health Repository)

    Meehan, Maria

    2012-02-05

    Abstract Background Protein tyrosine phosphatase receptor delta (PTPRD) is a member of a large family of protein tyrosine phosphatases which negatively regulate tyrosine phosphorylation. Neuroblastoma is a major childhood cancer arising from precursor cells of the sympathetic nervous system which is known to acquire deletions and alterations in the expression patterns of PTPRD, indicating a potential tumor suppressor function for this gene. The molecular mechanism, however, by which PTPRD renders a tumor suppressor effect in neuroblastoma is unknown. Results As a molecular mechanism, we demonstrate that PTPRD interacts with aurora kinase A (AURKA), an oncogenic protein that is over-expressed in multiple forms of cancer, including neuroblastoma. Ectopic up-regulation of PTPRD in neuroblastoma dephosphorylates tyrosine residues in AURKA resulting in a destabilization of this protein culminating in interfering with one of AURKA\\'s primary functions in neuroblastoma, the stabilization of MYCN protein, the gene of which is amplified in approximately 25 to 30% of high risk neuroblastoma. Conclusions PTPRD has a tumor suppressor function in neuroblastoma through AURKA dephosphorylation and destabilization and a downstream destabilization of MYCN protein, representing a novel mechanism for the function of PTPRD in neuroblastoma.

  18. A novel proapoptotic gene PANO encodes a post-translational modulator of the tumor suppressor p14ARF.

    Science.gov (United States)

    Watari, Akihiro; Li, Yang; Higashiyama, Shinji; Yutsudo, Masuo

    2012-02-01

    The protein p14ARF is a known tumor suppressor protein controlling cell proliferation and survival, which mainly localizes in nucleoli. However, the regulatory mechanisms that govern its activity or expression remain unclear. Here, we report that a novel proapoptotic nucleolar protein, PANO, modulates the expression and activity of p14ARF in HeLa cells. Overexpression of PANO enhances the stability of p14ARF protein by protecting it from degradation, resulting in an increase in p14ARF expression levels. Overexpression of PANO also induces apoptosis under low serum conditions. This effect is dependent on the nucleolar localization of PANO and inhibited by knocking-down p14ARF. Alternatively, PANO siRNA treated cells exhibit a reduction in p14ARF protein levels. In addition, ectopic expression of PANO suppresses the tumorigenicity of HeLa cells in nude mice. These results indicate that PANO is a new apoptosis-inducing gene by modulating the tumor suppressor protein, p14ARF, and may itself be a new candidate tumor suppressor gene. Copyright © 2011 Elsevier Inc. All rights reserved.

  19. A novel proapoptotic gene PANO encodes a post-translational modulator of the tumor suppressor p14ARF

    Energy Technology Data Exchange (ETDEWEB)

    Watari, Akihiro; Li, Yang; Higashiyama, Shinji; Yutsudo, Masuo, E-mail: yutsudo@biken.osaka-u.ac.jp

    2012-02-01

    The protein p14ARF is a known tumor suppressor protein controlling cell proliferation and survival, which mainly localizes in nucleoli. However, the regulatory mechanisms that govern its activity or expression remain unclear. Here, we report that a novel proapoptotic nucleolar protein, PANO, modulates the expression and activity of p14ARF in HeLa cells. Overexpression of PANO enhances the stability of p14ARF protein by protecting it from degradation, resulting in an increase in p14ARF expression levels. Overexpression of PANO also induces apoptosis under low serum conditions. This effect is dependent on the nucleolar localization of PANO and inhibited by knocking-down p14ARF. Alternatively, PANO siRNA treated cells exhibit a reduction in p14ARF protein levels. In addition, ectopic expression of PANO suppresses the tumorigenicity of HeLa cells in nude mice. These results indicate that PANO is a new apoptosis-inducing gene by modulating the tumor suppressor protein, p14ARF, and may itself be a new candidate tumor suppressor gene.

  20. The regulation of tumor suppressor protein, p53, and estrogen receptor (ERα) by resveratrol in breast cancer cells

    Science.gov (United States)

    Saluzzo, Julieta; Hallman, Kelly M.; Aleck, Katie; Dwyer, Brigitte; Quigley, Meghan; Mladenovik, Viktoria; Siebert, Amy E.; Dinda, Sumi

    2016-01-01

    Resveratrol (RES) is a natural antioxidant found abundantly in grapes, peanuts, and berries, and is known to possess anti-tumorigenic properties. However, there is a noticeable lack of studies on the mechanistic effects of Resveratrol on tumor suppressors. Previous studies from our laboratory have shown the tumor suppressor protein p53 and estrogen receptor-alpha (ERα) to be possible molecular targets for RES. In this study, the anti-estrogenic effects of RES were analyzed on the expression of ERα and p53. The breast cancer cells grown in stripped serum were treated with 60 μM RES, as the optimum concentration based on data obtained from a concentration study using 1-100 μM RES. Our studies indicate that RES caused a decrease in the levels of protein expression of p53 and ERα as compared to the control. Increasing concentrations of RES caused a four-fold decrease in cell number in comparison to estradiol. RES, in conjunction with ICI 182,780 (ICI), caused a down-regulation of both p53 and ERα as compared to the control. These observed effects on cell proliferation and regulation of both p53 and ERα by RES may lead to further understanding of the relationship between tumor suppressor proteins and steroid receptors in breast cancer cells. PMID:28191286

  1. Identification of the Adapter Molecule MTSS1 as a Potential Oncogene-Specific Tumor Suppressor in Acute Myeloid Leukemia.

    Directory of Open Access Journals (Sweden)

    Mirle Schemionek

    Full Text Available The adapter protein metastasis suppressor 1 (MTSS1 is implicated as a tumor suppressor or tumor promoter, depending on the type of solid cancer. Here, we identified Mtss1 expression to be increased in AML subsets with favorable outcome, while suppressed in high risk AML patients. High expression of MTSS1 predicted better clinical outcome of patients with normal-karyotype AML. Mechanistically, MTSS1 expression was negatively regulated by FLT3-ITD signaling but enhanced by the AML1-ETO fusion protein. DNMT3B, a negative regulator of MTSS1, showed strong binding to the MTSS1 promoter in PML-RARA positive but not AML1-ETO positive cells, suggesting that AML1-ETO leads to derepression of MTSS1. Pharmacological treatment of AML cell lines carrying the FLT3-ITD mutation with the specific FLT3 inhibitor PKC-412 caused upregulation of MTSS1. Moreover, treatment of acute promyelocytic cells (APL with all-trans retinoic acid (ATRA increased MTSS1 mRNA levels. Taken together, our findings suggest that MTSS1 might have a context-dependent function and could act as a tumor suppressor, which is pharmacologically targetable in AML patients.

  2. Protein tyrosine phosphatase receptor delta acts as a neuroblastoma tumor suppressor by destabilizing the aurora kinase a oncogene

    Directory of Open Access Journals (Sweden)

    Meehan Maria

    2012-02-01

    Full Text Available Abstract Background Protein tyrosine phosphatase receptor delta (PTPRD is a member of a large family of protein tyrosine phosphatases which negatively regulate tyrosine phosphorylation. Neuroblastoma is a major childhood cancer arising from precursor cells of the sympathetic nervous system which is known to acquire deletions and alterations in the expression patterns of PTPRD, indicating a potential tumor suppressor function for this gene. The molecular mechanism, however, by which PTPRD renders a tumor suppressor effect in neuroblastoma is unknown. Results As a molecular mechanism, we demonstrate that PTPRD interacts with aurora kinase A (AURKA, an oncogenic protein that is over-expressed in multiple forms of cancer, including neuroblastoma. Ectopic up-regulation of PTPRD in neuroblastoma dephosphorylates tyrosine residues in AURKA resulting in a destabilization of this protein culminating in interfering with one of AURKA's primary functions in neuroblastoma, the stabilization of MYCN protein, the gene of which is amplified in approximately 25 to 30% of high risk neuroblastoma. Conclusions PTPRD has a tumor suppressor function in neuroblastoma through AURKA dephosphorylation and destabilization and a downstream destabilization of MYCN protein, representing a novel mechanism for the function of PTPRD in neuroblastoma.

  3. T63, a new 4-arylidene curcumin analogue, induces cell cycle arrest and apoptosis through activation of the reactive oxygen species-FOXO3a pathway in lung cancer cells.

    Science.gov (United States)

    Liu, Hao; Zhou, Bin-Hua; Qiu, Xu; Wang, Hong-Sheng; Zhang, Fan; Fang, Rui; Wang, Xian-Feng; Cai, Shao-Hui; Du, Jun; Bu, Xian-Zhang

    2012-12-15

    Curcumin (diferuloylmethane) is a natural polyphenol product of the plant Curcuma longa and has a diversity of antitumor activities. T63, a new 4-arylidene curcumin analogue, was reported to inhibit proliferation of lung cancer cells. However, its precise molecular antitumor mechanisms have not been well elucidated. Here, we showed that T63 could significantly inhibit the proliferation of A549 and H460 human lung cell lines via induction of G0/G1 cell cycle arrest and apoptosis. We found that the reactive oxygen species (ROS)-activated FOXO3a cascade plays a central role in T63-induced cell proliferation inhibition. Mechanistically, enhancement of ROS production by T63 induced FOXO3a expression and nuclear translocation through activation of p38MAPK and inhibition of AKT, subsequently elevating the expression of FOXO3a target genes, including p21, p27, and Bim, and then increased the levels of activated caspase-3 and decreased the levels of cyclin D1. Moreover, the antioxidant N-acetylcysteine markedly blocked the above effects, and small interfering RNA-mediated knockdown of FOXO3a also significantly decreased T63-induced cell cycle arrest and apoptosis. In vivo experiments showed that T63 significantly suppressed the growth of A549 lung cancer xenograft tumors, associated with proliferation suppression and apoptosis induction in tumor tissues, without inducing any notable major organ-related toxicity. These data indicated that the novel curcumin analogue T63 is a potent antitumor agent that induces cell cycle arrest and apoptosis and has significant therapeutic potential for lung cancer. Copyright © 2012 Elsevier Inc. All rights reserved.

  4. Resveratrol ameliorates hyperglycemia-induced renal tubular oxidative stress damage via modulating the SIRT1/FOXO3a pathway.

    Science.gov (United States)

    Wang, Xueling; Meng, Linghang; Zhao, Long; Wang, Zengfu; Liu, Haiying; Liu, Gang; Guan, Guangju

    2017-04-01

    Oxidative stress plays an important role in the development and progression of diabetic nephropathy (DN). We aimed to investigate if resveratrol (RSV) could ameliorate hyperglycemia-induced oxidative stress in renal tubules via modulating the SIRT1/FOXO3a pathway. The effects of RSV on diabetes rats were assessed by periodic acid-Schiff, Masson staining, immunohistochemistry, and western blot analyses. Additionally, oxidative indicators (such as catalase, superoxide dismutase, reactive oxygen species, and malondialdehyde), the deacetylase activity of SIRT1 and protein expressions of SIRT1, FOXO3a, and acetylated-FOXO3a were measured. These indicators were similarly evaluated in an in vitro study. Furthermore, the silencing of SIRT1 was used to confirm its role in the resistance to oxidative stress and the relationship between SIRT1 and FOXO3a in vitro. After 16weeks of RSV treatment, the renal function and glomerulosclerosis of rats with DN was dramatically ameliorated. RSV treatment increased SIRT1 deacetylase activity, subsequently decreasing the expression of acetylated-FOXO3a and inhibiting the oxidative stress caused by hyperglycemia both in vivo and in vitro. The silencing of SIRT1 in HK-2 cells aggravated the high glucose-induced oxidative stress and overexpression of acetylated-FOXO3a; RSV treatment failed to protect against these effects. RSV modulates the SIRT1/FOXO3a pathway by increasing SIRT1 deacetylase activity, subsequently ameliorating hyperglycemia-induced renal tubular oxidative stress damage. This mechanism provides the basis for a new approach to developing an effective DN treatment, which is of great clinical significance for reducing the morbidity and mortality associated with DN. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  5. An epigenetic genome-wide screen identifies SPINT2 as a novel tumor suppressor gene in pediatric medulloblastoma.

    Science.gov (United States)

    Kongkham, Paul N; Northcott, Paul A; Ra, Young Shin; Nakahara, Yukiko; Mainprize, Todd G; Croul, Sidney E; Smith, Christian A; Taylor, Michael D; Rutka, James T

    2008-12-01

    Medulloblastoma (MB) is a malignant cerebellar tumor that occurs primarily in children. The hepatocyte growth factor (HGF)/MET pathway has an established role in both normal cerebellar development as well as the development and progression of human brain tumors, including MB. To identify novel tumor suppressor genes involved in MB pathogenesis, we performed an epigenome-wide screen in MB cell lines, using 5-aza-2'deoxycytidine to identify genes aberrantly silenced by promoter hypermethylation. Using this technique, we identified an inhibitor of HGF/MET signaling, serine protease inhibitor kunitz-type 2 (SPINT2/HAI-2), as a putative tumor suppressor silenced by promoter methylation in MB. In addition, based on single nucleotide polymorphism array analysis in primary MB samples, we identified hemizygous deletions targeting the SPINT2 locus in addition to gains on chromosome 7 encompassing the HGF and MET loci. SPINT2 gene expression was down-regulated and MET expression was up-regulated in 73.2% and 45.5% of tumors, respectively, by quantitative real-time PCR. SPINT2 promoter methylation was detected in 34.3% of primary MBs examined by methylation-specific PCR. SPINT2 reexpression in MB cell lines reduced proliferative capacity, anchorage independent growth, cell motility in vitro, and increased overall survival times in vivo in a xenograft model (P<0.0001). Taken together, these data support the role of SPINT2 as a putative tumor suppressor gene in MB, and further implicate dysregulation of the HGF/MET signaling pathway in the pathogenesis of MB.

  6. Association study of FOXO3A SNPs and aging phenotypes in Danish oldest-old individuals

    DEFF Research Database (Denmark)

    Soerensen, Mette; Nygaard, Marianne; Dato, Serena

    2015-01-01

    -old Danes (age 92-93) with 4 phenotypes known to predict their survival: cognitive function, hand grip strength, activity of daily living (ADL), and self-rated health. Based on previous studies in humans and foxo animal models, we also explore self-reported diabetes, cancer, cardiovascular disease......, osteoporosis, and bone (femur/spine/hip/wrist) fracture. Gene-based testing revealed significant associations of FOXO3A variation with ADL (P = 0.044) and bone fracture (P = 0.006). The single-SNP statistics behind the gene-based analysis indicated increased ADL (decreased disability) and reduced bone fracture...

  7. The tumor suppressor Lgl1 regulates front-rear polarity of migrating cells.

    Science.gov (United States)

    Ravid, Shoshana

    2014-01-01

    Cell migration is a highly integrated, multistep process that plays an important role in physiological and pathological processes. The migrating cell is highly polarized, with complex regulatory pathways that integrate its component processes spatially and temporally. The Drosophila tumor suppressor, Lethal (2) giant larvae (Lgl), regulates apical-basal polarity in epithelia and asymmetric cell division. But little is known about the role of Lgl in establishing cell polarity in migrating cells. Recently, we showed that the mammalian Lgl1 interacts directly with non-muscle myosin IIA (NMIIA), inhibiting its ability to assemble into filaments in vitro. Lgl1 also regulates the cellular localization of NMIIA, the maturation of focal adhesions, and cell migration. We further showed that phosphorylation of Lgl1 by aPKCζ prevents its interaction with NMIIA and is important for Lgl1 and acto-NMII cytoskeleton cellular organization. Lgl is a critical downstream target of the Par6-aPKC cell polarity complex; we showed that Lgl1 forms two distinct complexes in vivo, Lgl1-NMIIA and Lgl1-Par6-aPKCζ in different cellular compartments. We further showed that aPKCζ and NMIIA compete to bind directly to Lgl1 through the same domain. These data provide new insights into the role of Lgl1, NMIIA, and Par6-aPKCζ in establishing front-rear polarity in migrating cells. In this commentary, I discuss the role of Lgl1 in the regulation of the acto-NMII cytoskeleton and its regulation by the Par6-aPKCζ polarity complex, and how Lgl1 activity may contribute to the establishment of front-rear polarity in migrating cells.

  8. Mechanism of inhibition of the tumor suppressor Patched by Sonic Hedgehog.

    Science.gov (United States)

    Tukachinsky, Hanna; Petrov, Kostadin; Watanabe, Miyako; Salic, Adrian

    2016-10-04

    The Hedgehog cell-cell signaling pathway is crucial for animal development, and its misregulation is implicated in numerous birth defects and cancers. In unstimulated cells, pathway activity is inhibited by the tumor suppressor membrane protein, Patched. Hedgehog signaling is triggered by the secreted Hedgehog ligand, which binds and inhibits Patched, thus setting in motion the downstream events in signal transduction. Despite its critical importance, the mechanism by which Hedgehog antagonizes Patched has remained unknown. Here, we show that vertebrate Patched1 inhibition is caused by direct, palmitate-dependent interaction with the Sonic Hedgehog ligand. We find that a short palmitoylated N-terminal fragment of Sonic Hedgehog binds Patched1 and, strikingly, is sufficient to inhibit it and to activate signaling. The rest of Sonic Hedgehog confers high-affinity Patched1 binding and internalization through a distinct binding site, but, surprisingly, it is not absolutely required for signaling. The palmitate-dependent interaction with Patched1 is specifically impaired in a Sonic Hedgehog mutant causing human holoprosencephaly, the most frequent congenital brain malformation, explaining its drastically reduced potency. The palmitate-dependent interaction is also abolished in constitutively inhibited Patched1 point mutants causing the Gorlin cancer syndrome, suggesting that they might adopt a conformation distinct from the wild type. Our data demonstrate that Sonic Hedgehog signals via the palmitate-dependent arm of a two-pronged contact with Patched1. Furthermore, our results suggest that, during Hedgehog signaling, ligand binding inhibits Patched by trapping it in an inactive conformation, a mechanism that explains the dramatically reduced activity of oncogenic Patched1 mutants.

  9. MTUS1 tumor suppressor and its miRNA regulators in fibroadenoma and breast cancer.

    Science.gov (United States)

    Kara, Murat; Kaplan, Mehmet; Bozgeyik, Ibrahim; Ozcan, Onder; Celik, Ozgur Ilhan; Bozgeyik, Esra; Yumrutas, Onder

    2016-08-10

    Breast cancer is major public health problem predominantly effects female population. Current therapeutic approaches to deal with breast cancer are still lack of effectiveness. Thus, identifying/developing novel strategies to fight against breast cancer is very important. The frequent deletions at 8p21.3-22 chromosomal location nearby D8S254 marker enabled the discovery of a novel tumor suppressor gene, MTUS1. Subsequently, MTUS1 was demonstrated to be less expressed in a variety cancer types including breast cancer. Also, it is obvious that gene expression is widely regulated by miRNAs. Here, we aimed to report differential expression of MTUS1 and its regulatory miRNAs in breast cancer and fibroadenoma tissues. Dynamic analysis of MTUS1 expression levels and its miRNAs regulators were attained by Fluidigm 96×96 Dynamic Array Expression chips and reactions were performed in Fluidigm BioMark™ HD System qPCR. Consequently, MTUS1 mRNA levels were significantly diminished in breast cancer tissues and elevated in fibroadenoma tissues. Also, among MTUS1 targeting miRNAs, miR-183-5p was identified to be overexpressed in breast cancer and down-regulated in fibroadenoma tissues. Also, expression levels of MTUS1 and miR-183-5p were well correlated with clinical parameters. In particular, MTUS1 expression was found to be diminished and miR-183-5p expression was elevated with the advancing stage. In conclusion, as a potential therapeutic target, miR-183-5p can be a chief regulator of MTUS1 and MTUS1-miR-183-5p axis may have significant influence in the pathology of breast cancer.

  10. BAX and tumor suppressor TRP53 are important in regulating mutagenesis in spermatogenic cells in mice.

    Science.gov (United States)

    Xu, Guogang; Vogel, Kristine S; McMahan, C Alex; Herbert, Damon C; Walter, Christi A

    2010-12-01

    During the first wave of spermatogenesis, and in response to ionizing radiation, elevated mutant frequencies are reduced to a low level by unidentified mechanisms. Apoptosis is occurring in the same time frame that the mutant frequency declines. We examined the role of apoptosis in regulating mutant frequency during spermatogenesis. Apoptosis and mutant frequencies were determined in spermatogenic cells obtained from Bax-null or Trp53-null mice. The results showed that spermatogenic lineage apoptosis was markedly decreased in Bax-null mice and was accompanied by a significantly increased spontaneous mutant frequency in seminiferous tubule cells compared to that of wild-type mice. Apoptosis profiles in the seminiferous tubules for Trp53-null were similar to control mice. Spontaneous mutant frequencies in pachytene spermatocytes and in round spermatids from Trp53-null mice were not significantly different from those of wild-type mice. However, epididymal spermatozoa from Trp53-null mice displayed a greater spontaneous mutant frequency compared to that from wild-type mice. A greater proportion of spontaneous transversions and a greater proportion of insertions/deletions 15 days after ionizing radiation were observed in Trp53-null mice compared to wild-type mice. Base excision repair activity in mixed germ cell nuclear extracts prepared from Trp53-null mice was significantly lower than that for wild-type controls. These data indicate that BAX-mediated apoptosis plays a significant role in regulating spontaneous mutagenesis in seminiferous tubule cells obtained from neonatal mice, whereas tumor suppressor TRP53 plays a significant role in regulating spontaneous mutagenesis between postmeiotic round spermatid and epididymal spermatozoon stages of spermiogenesis.

  11. Repression of estrogen receptor {beta} function by putative tumor suppressor DBC1

    Energy Technology Data Exchange (ETDEWEB)

    Koyama, Satoshi [Department of Obstetrics and Gynecology, Graduate School of Medicine, The University of Tokyo, Hongo 7-3-1 Bunkyo-ku, Tokyo 113-8655 (Japan); Wada-Hiraike, Osamu, E-mail: osamuwh-tky@umin.ac.jp [Department of Obstetrics and Gynecology, Graduate School of Medicine, The University of Tokyo, Hongo 7-3-1 Bunkyo-ku, Tokyo 113-8655 (Japan); Nakagawa, Shunsuke; Tanikawa, Michihiro; Hiraike, Haruko; Miyamoto, Yuichiro; Sone, Kenbun; Oda, Katsutoshi [Department of Obstetrics and Gynecology, Graduate School of Medicine, The University of Tokyo, Hongo 7-3-1 Bunkyo-ku, Tokyo 113-8655 (Japan); Fukuhara, Hiroshi [Department of Urology, Graduate School of Medicine, The University of Tokyo, Hongo 7-3-1 Bunkyo-ku, Tokyo 113-8655 (Japan); Nakagawa, Keiichi [Department of Radiology, Graduate School of Medicine, The University of Tokyo, Hongo 7-3-1 Bunkyo-ku, Tokyo 113-8655 (Japan); Kato, Shigeaki [SORST, Japan Science and Technology, Honcho 4-1-8, Kawaguchi, Saitama 332-0012 (Japan); Institute of Molecular and Cellular Biosciences, The University of Tokyo, Yayoi 1-1-1 Bunkyo-ku, Tokyo 113-0034 (Japan); Yano, Tetsu; Taketani, Yuji [Department of Obstetrics and Gynecology, Graduate School of Medicine, The University of Tokyo, Hongo 7-3-1 Bunkyo-ku, Tokyo 113-8655 (Japan)

    2010-02-12

    It has been well established that estrogen is involved in the pathophysiology of breast cancer. Estrogen receptor (ER) {alpha} appears to promote the proliferation of cancer tissues, while ER{beta} can protect against the mitogenic effect of estrogen in breast tissue. The expression status of ER{alpha} and ER{beta} may greatly influence on the development, treatment, and prognosis of breast cancer. Previous studies have indicated that the deleted in breast cancer 1 (DBC1/KIAA1967) gene product has roles in regulating functions of nuclear receptors. The gene encoding DBC1 is a candidate for tumor suppressor identified by genetic search for breast cancer. Caspase-dependent processing of DBC1 promotes apoptosis, and depletion of the endogenous DBC1 negatively regulates p53-dependent apoptosis through its specific inhibition of SIRT1. In addition, DBC1 modulates ER{alpha} expression and promotes breast cancer cell survival by binding to ER{alpha}. Here we report an ER{beta}-specific repressive function of DBC1. Immunoprecipitation and immunofluorescence studies show that ER{beta} and DBC1 interact in a ligand-independent manner similar to ER{alpha}. In vitro pull-down assays revealed a direct interaction between DBC1 amino-terminus and activation function-1/2 domain of ER{beta}. Although DBC1 shows no influence on the ligand-dependent transcriptional activation function of ER{alpha}, the expression of DBC1 negatively regulates the ligand-dependent transcriptional activation function of ER{beta}in vivo, and RNA interference-mediated depletion of DBC1 stimulates the transactivation function of ER{beta}. These results implicate the principal role of DBC1 in regulating ER{beta}-dependent gene expressions.

  12. In Vitro and In Vivo Effects of Tumor Suppressor Gene PTEN on Endometriosis: An Experimental Study

    Science.gov (United States)

    Lv, Juan; Zhu, Qiaoying; Jia, Xuemei; Yu, Ningzhu; Li, Qian

    2016-01-01

    Background Endometriosis can cause dysmenorrhea and infertility. Its pathogenesis has not yet been clarified and its treatment continues to pose enormous challenges. The protein tyrosine phosphatase (PTEN) gene is a tumor suppressor gene. The aim of this study was to investigate the role and significance of PTEN protein in the occurrence, development, and treatment of endometriosis through changes in apoptosis rate, cell cycle, and angiogenesis. Material/Methods PTEN was overexpressed and silenced in lentiviral vectors and inserted into primary endometrial cells. The changes in cell cycle and apoptosis in the different PTEN expression groups were evaluated using flow cytometry. Vessel growth mimicry was observed using 3-dimensional culture. A human-mouse chimeric endometriosis model was constructed using SCID mice. Hematoxylin and eosin staining and immunohistochemistry were used to detect pathological changes in ectopic endometrial tissues and the expression of VEGF protein in a human-mouse chimeric endometriosis mouse model. Results PTEN overexpression significantly increased apoptosis and inhibited the cell cycle compared with the silenced and control groups. Furthermore, cells expressing low PTEN levels were better able to undergo vasculogenic mimicry, and exhibited significantly increased angiogenesis compared to cells overexpressing PTEN. We found that ectopic foci were more easily formed in the endometrial tissue of SCID mice with low PTEN expression, and the VEGF expression in this group was relatively high. Conclusions PTEN inhibits the occurrence and development of endometriosis by regulating angiogenesis and the apoptosis and cell cycle of endometrial cells; therefore, we propose that the PTEN gene can be used to treat endometriosis. PMID:27744455

  13. Cellular retinol binding protein 1 could be a tumor suppressor gene in cervical cancer

    Science.gov (United States)

    Mendoza-Rodriguez, Mónica; Arreola, Hugo; Valdivia, Alejandra; Peralta, Raúl; Serna, Humberto; Villegas, Vanessa; Romero, Pablo; Alvarado-Hernández, Beatriz; Paniagua, Lucero; Marrero-Rodríguez, Daniel; Meraz, Marco A; Salcedo, Mauricio

    2013-01-01

    Aims: Cervical Cancer (CC) is one of the most important health problems in women. It frequently presents genetic changes at chromosome region 3q21. This region contains the Cellular Retinol Binding Protein 1 gene (CRBP1) which has been implicated as an important element in the development of other types of cancer. The main goal of the present work was to determine the molecular alterations of CRBP1 and its relationship to CC. Methods: To determine the molecular alterations of CRBP1 gene in CC; twenty-six CC and twenty-six healthy cervix samples were evaluated for: 1) Copy number gain by real-time PCR analysis, 2) expression levels by an immunohistochemistry assay on tissue microarray, and 3) the methylation status of the CRBP1 promoter region. Results: The increase in CRBP1 copy number was observed in 10 out of the 26 CC samples analyzed, while healthy cervices samples showed no changes in the copy number. In addition, there was a lack of expression of the CRBP1 gene in an important number of the CC samples (17/26), and the CRBP1 gene promoter was methylated in 15/26 of the CC samples. Interestingly, there was a significant association between the lack of expression of the CRBP1 gene and its methylation status. Conclusions: The data indicates that, both activating and inactivating changes in the CRBP1 gene could be significant events in the development and progression of CC, and the lack of expression of the CRBP1 protein could be related with to the development of CC. We believe that there is enough evidence to consider to CRBP1 gene as a tumor suppressor gene for CC. PMID:24040446

  14. Intracellular HMGB1 as a novel tumor suppressor of pancreatic cancer

    Science.gov (United States)

    Kang, Rui; Xie, Yangchun; Zhang, Qiuhong; Hou, Wen; Jiang, Qingping; Zhu, Shan; Liu, Jinbao; Zeng, Dexing; Wang, Haichao; Bartlett, David L; Billiar, Timothy R; Zeh, Herbert J; Lotze, Michael T; Tang, Daolin

    2017-01-01

    Pancreatic ductal adenocarcinoma (PDAC) driven by oncogenic K-Ras remains among the most lethal human cancers despite recent advances in modern medicine. The pathogenesis of PDAC is partly attributable to intrinsic chromosome instability and extrinsic inflammation activation. However, the molecular link between these two events in pancreatic tumorigenesis has not yet been fully established. Here, we show that intracellular high mobility group box 1 (HMGB1) remarkably suppresses oncogenic K-Ras-driven pancreatic tumorigenesis by inhibiting chromosome instability-mediated pro-inflammatory nucleosome release. Conditional genetic ablation of either single or both alleles of HMGB1 in the pancreas renders mice extremely sensitive to oncogenic K-Ras-driven initiation of precursor lesions at birth, including pancreatic intraepithelial neoplasms, intraductal papillary mucinous neoplasms, and mucinous cystic neoplasms. Loss of HMGB1 in the pancreas is associated with oxidative DNA damage and chromosomal instability characterized by chromosome rearrangements and telomere abnormalities. These lead to inflammatory nucleosome release and propagate K-Ras-driven pancreatic tumorigenesis. Extracellular nucleosomes promote interleukin 6 (IL-6) secretion by infiltrating macrophages/neutrophils and enhance oncogenic K-Ras signaling activation in pancreatic lesions. Neutralizing antibodies to IL-6 or histone H3 or knockout of the receptor for advanced glycation end products all limit K-Ras signaling activation, prevent cancer development and metastasis/invasion, and prolong animal survival in Pdx1-Cre;K-RasG12D/+;Hmgb1−/− mice. Pharmacological inhibition of HMGB1 loss by glycyrrhizin limits oncogenic K-Ras-driven tumorigenesis in mice under inflammatory conditions. Diminished nuclear and total cellular expression of HMGB1 in PDAC patients correlates with poor overall survival, supporting intracellular HMGB1 as a novel tumor suppressor with prognostic and therapeutic relevance in

  15. Interaction of hepatitis B virus with tumor suppressor gene p53: its significance and biological function

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The mechanism of the interaction of hepatitis B virus (HBV) with tumor suppressor p53 and its role in the hepatocarcinogenesis have been studied by PCR-directed sequencing, gel shift assays and in situ ultraviolet cross-linking assay. The biological function of the interaction of HBV with p53 gene was investigated by co-transfection of chloramphenicol acetyltransferase (CAT) reporter gene, p53 and HBV DNA, and quantitative PCR. Among the 16 primary hepatocellular carcinoma (PHC) samples, 13 were HBV-DNA positive,10 HBxAg positive and 9 p53 protein positive. The p53 gene point mutation was found in 5 samples, one of which had a G to T substitution located at codon 249. After analyzing the HBV genome by a computer program, a p53 response element binding sequence was found in HBV genome at upstream of enhancer I, from 1047 to 1059 nucleotides. This sequence could specifically bind to p53 protein, increase p53 protein accumulation in the PHC cells and stimulate the transactivating activity of p53 and HBV replication .The results also revealed that HBxAg could combine with p53 protein to form a complex in the cells and enhance CAT expression. Immunocytochemical staining showed that p53 protein complex was located in the cytoplasm and the process of p53 entry to nuclei was, in part, blocked. From our results, we conclude that the mutation of p53 gene at codon 249 is infrequent in HBV-associated PHC, the DNA-protein binding between HBV and p53, and the protein-protein binding between HBxAg and p53 might lead to the reduction or inactivation of p53 protein, which in turn resulting in HBV-associated hepatocarcinogenesis.

  16. Expression of SOCS1 and the downstream targets of its putative tumor suppressor functions in prostate cancer.

    Science.gov (United States)

    Chevrier, Martin; Bobbala, Diwakar; Villalobos-Hernandez, Alberto; Khan, Md Gulam Musawwir; Ramanathan, Sheela; Saucier, Caroline; Ferbeyre, Gerardo; Geha, Sameh; Ilangumaran, Subburaj

    2017-02-24

    Suppressor of cytokine signaling 1 (SOCS1) is considered a tumor suppressor due to frequent epigenetic and micro-RNA-mediated repression of its gene expression in diverse cancers. In prostate cancer (PCa), elevated expression of miR-30d that targets SOCS1 mRNA is associated with increased risk of disease recurrence. SOCS1 can mediate its tumor suppressor functions by diverse mechanisms such as inhibiting the JAK-STAT signaling pathway, promoting the tumor suppressor functions of p53, attenuating MET receptor tyrosine kinase signaling and blocking the oncogenic potential of the cell cycle inhibitor p21(CIP1) (p21). Here, we studied the expression of SOCS1 and the downstream targets of its putative tumor suppressor functions (p53, MET and p21) in human PCa specimens to evaluate their significance as markers of disease prognosis. Tissue microarrays were constructed of 78 archived prostatectomy specimens that were grouped according to the recommendations of the International Society of Urological Pathology (ISUP) based on the Gleason patterns. SOCS1, p53, MET and p21 protein expression were evaluated by immunohistochemical staining alongside the common prostate cancer-related markers Ki67, prostein and androgen receptor. Statistical correlations between the staining intensities of these markers and ISUP grade groups, local invasion or lymph node metastasis were evaluated. SOCS1 showed diffuse staining in the prostatic epithelium. SOCS1 staining intensity correlated inversely with the ISUP grade groups (ρ = -0.4687, p <0.0001) and Ki67 (ρ = -0.2444, p = 0.031), and positively with prostein (ρ = 0.3511, p = 0.0016). Changes in SOCS1 levels did not significantly associate with those of p53, MET or p21. However, p21 positively correlated with androgen receptor expression (ρ = -0.1388, p = 0.0003). A subset of patients with regional lymph node metastasis, although small in number, showed reduced SOCS1 expression and increased expression of

  17. Epigenetic silencing of MAL, a putative tumor suppressor gene, can contribute to human epithelium cell carcinoma

    Directory of Open Access Journals (Sweden)

    Zhang Jun

    2010-11-01

    Full Text Available Abstract Background To identify new and useful candidate biomarkers in head and neck squamous cell carcinoma (HNSCC, we performed a genome-wide survey and found that Myelin and lymphocyte-associated protein (MAL was a gene that was markedly down-regulated in HNSCC. Hence, we investigated the mechanism of MAL silencing and the effects of MAL on the proliferation, invasion, and apoptotic potential in HNSCC. Results MAL was significantly down-regulated in 91.7% of HNSCC specimens at the mRNA level as compared with adjacent normal tissues (P = 0.0004. Moreover, the relative transcript levels of the MAL gene were remarkably decreased by five-fold in nine HNSCC cell lines as compared with normal head and neck epithelium cells. MAL gene expression was restored in 44%, 67%, and 89% in HNSCC cell lines treated with TSA, 5-Aza-dC, and TSA plus 5-Aza-dC, respectively. Furthermore, bisulfate-treated DNA sequencing demonstrated that the two CpG islands (that is, M1 and M2 located in MAL promoter region were completely methylated in the HNSCC cell lines (CpG methylated ratio was more than 90%, and only one CpG island (that is, M1 was partially methylated in HNSCC tissues (CpG methylated ratio between 20% and 90%. A significant reduction in cell proliferation and a change in the cell cycle profile were also observed in MAL transfectants. Matrigel assay demonstrated that the invasiveness of HNSCC cells significantly decreased. A significant increase in the population of apoptotic cells was observed in MAL transfected cells. The exogenous expression of the MAL gene suppressed malignant phenotypes, while the cell death induced by MAL gene transfer was a result of apoptosis as demonstrated by the induction of cleavage of the poly (that is, ADP-ribose polymerase. Additionally, tumor growth was suppressed in cells expressing MAL as compared with cells not expressing MAL. Conclusion Our data suggest that the epigenetic inactivation of MAL, as a candidate tumor

  18. Blunting Autoantigen-induced FOXO3a Protein Phosphorylation and Degradation Is a Novel Pathway of Glucocorticoids for the Treatment of Systemic Lupus Erythematosus.

    Science.gov (United States)

    Lu, Mudan; Xu, Wei; Gao, Bo; Xiong, Sidong

    2016-09-16

    Systemic lupus erythematosus (SLE) is a chronic inflammatory autoimmune disease affecting multiple organs. Glucocorticoids (GCs), the potent anti-inflammatory drugs, remain as a cornerstone in the treatment for SLE; nevertheless, their clinical efficacy is compromised by the side effects of long term treatment and resistance. To improve the therapeutic efficacy of GCs in SLE, it is important to further decipher the molecular mechanisms of how GCs exert their anti-inflammatory effects. In this investigation, FOXO3a was identified as a molecule that was down-regulated in the course of SLE. Of interest, GC treatment was found to rescue FOXO3a expression both in SLE mice and in SLE patients. Gain- and loss-of-function studies demonstrated that FOXO3a played a crucial role in GC treatment of SLE via inhibiting inflammatory responses. Further studies showed that the up-regulation of FOXO3a by GCs relied on the suppression of pI3K/AKT-mediated FOXO3a phosphorylation and the arrest of FOXO3a in the nucleus. Finally, our data revealed that FOXO3a was critical for GC-mediated inhibition of NF-κB activity, which might involve its interaction with NF-κB p65 protein. Collectively, these data indicated that FOXO3a played an important role in GC treatment of SLE by suppressing pro-inflammatory response, and targeting FOXO3a might provide a novel therapeutic strategy against SLE.

  19. Genomic Analyses Reveal Global Functional Alterations That Promote Tumor Growth and Novel Tumor Suppressor Genes in Natural Killer-Cell Malignancies

    DEFF Research Database (Denmark)

    Kucuk, Can; Iqbal, Javeed; J. deLeeuw, Ronald

    in cell proliferation, growth and energy metabolic processes important for the neoplastic cells. In deleted regions, genes showing decreased expression included transcription factors or repressors (e.g. SP4, PRDM1, NCOR1 and ZNF10), tumor suppressors or negative regulators of the cell cycle (e.g. CDKN2C...... treatment suggestive of a role of PRDM1 on the regulation of NK-cell activation. Conclusion: Combination of high resolution genomic and transcriptional profiling in NK-cell malignancies has provided evidence of a general tumor promoting effect of genomic copy number alterations as well as the identification...

  20. Differential Splicing of Oncogenes and Tumor Suppressor Genes in African- and Caucasian-American Populations: Contributing Factor in Prostate Cancer Disparities

    Science.gov (United States)

    2015-10-01

    vehicle or CAL-101 treatment (ANOVA, n=5 independent mice for each treatment group at each time point). (c) Intravenous tail vein with 105 PC-3 cells...combining miRNA expression profiling and coexpression network analysis. Although these profiling studies have begun to shed light on the involvement of...STAT1 FOXO3A β-Actin FOXO3A β-Actin FOXO3A β-Actin LNCaP # * N miR-1 iR -513c miR-96 antag antag mimic MDA PCa 2b C as pa se -3 /7 a ct iv ity

  1. Angiocrine factors modulate tumor proliferation and motility through EphA2 repression of Slit2 tumor suppressor function in endothelium.

    Science.gov (United States)

    Brantley-Sieders, Dana M; Dunaway, Charlene M; Rao, Meghana; Short, Sarah; Hwang, Yoonha; Gao, Yandong; Li, Deyu; Jiang, Aixiang; Shyr, Yu; Wu, Jane Y; Chen, Jin

    2011-02-01

    It is well known that tumor-derived proangiogenic factors induce neovascularization to facilitate tumor growth and malignant progression. However, the concept of "angiocrine" signaling, in which signals produced by endothelial cells elicit tumor cell responses distinct from vessel function, has been proposed, yet remains underinvestigated. Here, we report that angiocrine factors secreted from endothelium regulate tumor growth and motility. We found that Slit2, which is negatively regulated by endothelial EphA2 receptor, is one such tumor suppressive angiocrine factor. Slit2 activity is elevated in EphA2-deficient endothelium. Blocking Slit activity restored angiocrine-induced tumor growth/motility, whereas elevated Slit2 impaired growth/motility. To translate our findings to human cancer, we analyzed EphA2 and Slit2 expression in human cancer. EphA2 expression inversely correlated with Slit2 in the vasculature of invasive human ductal carcinoma samples. Moreover, analysis of large breast tumor data sets revealed that Slit2 correlated positively with overall and recurrence-free survival, providing clinical validation for the tumor suppressor function for Slit2 in human breast cancer. Together, these data support a novel, clinically relevant mechanism through which EphA2 represses Slit2 expression in endothelium to facilitate angiocrine-mediated tumor growth and motility by blocking a tumor suppressive signal.

  2. Complement C1q activates tumor suppressor WWOX to induce apoptosis in prostate cancer cells.

    Directory of Open Access Journals (Sweden)

    Qunying Hong

    Full Text Available BACKGROUND: Tissue exudates contain low levels of serum complement proteins, and their regulatory effects on prostate cancer progression are largely unknown. We examined specific serum complement components in coordinating the activation of tumor suppressors p53 and WWOX (also named FOR or WOX1 and kinases ERK, JNK1 and STAT3 in human prostate DU145 cells. METHODOLOGY/PRINCIPAL FINDINGS: DU145 cells were cultured overnight in 1% normal human serum, or in human serum depleted of an indicated complement protein. Under complement C1q- or C6-free conditions, WOX1 and ERK were mainly present in the cytoplasm without phosphorylation, whereas phosphorylated JNK1 was greatly accumulated in the nuclei. Exogenous C1q rapidly restored the WOX1 activation (with Tyr33 phosphorylation in less than 2 hr. Without serum complement C9, p53 became activated, and hyaluronan (HA reversed the effect. Under C6-free conditions, HA induced activation of STAT3, an enhancer of metastasis. Notably, exogenous C1q significantly induced apoptosis of WOX1-overexpressing DU145 cells, but not vehicle-expressing cells. A dominant negative and Y33R mutant of WOX1 blocked the apoptotic effect. C1q did not enhance p53-mediated apoptosis. By total internal reflection fluorescence (TIRF microscopy, it was determined that C1q destabilized adherence of WOX1-expressing DU145 cells by partial detaching and inducing formation of clustered microvilli for focal adhesion particularly in between cells. These cells then underwent shrinkage, membrane blebbing and death. Remarkably, as determined by immunostaining, benign prostatic hyperplasia and prostate cancer were shown to have a significantly reduced expression of tissue C1q, compared to age-matched normal prostate tissues. CONCLUSIONS/SIGNIFICANCE: We conclude that complement C1q may induce apoptosis of prostate cancer cells by activating WOX1 and destabilizing cell adhesion. Downregulation of C1q enhances prostate hyperplasia and cancerous

  3. Myeloid-derived suppressor cells modulate immune responses independently of NADPH oxidase in the ovarian tumor microenvironment in mice.

    Directory of Open Access Journals (Sweden)

    Heidi E Godoy

    Full Text Available The phagocyte NADPH oxidase generates superoxide anion and downstream reactive oxidant intermediates in response to infectious threat, and is a critical mediator of antimicrobial host defense and inflammatory responses. Myeloid-derived suppressor cells (MDSCs are a heterogeneous population of immature myeloid cells that are recruited by cancer cells, accumulate locally and systemically in advanced cancer, and can abrogate anti-tumor immunity. Prior studies have implicated the phagocyte NADPH oxidase as being an important component promoting MDSC accumulation and immunosuppression in cancer. We therefore used engineered NADPH oxidase-deficient (p47 (phox-/- mice to delineate the role of this enzyme complex in MDSC accumulation and function in a syngeneic mouse model of epithelial ovarian cancer. We found that the presence of NADPH oxidase did not affect tumor progression. The accumulation of MDSCs locally and systemically was similar in tumor-bearing wild-type (WT and p47 (phox-/- mice. Although MDSCs from tumor-bearing WT mice had functional NADPH oxidase, the suppressive effect of MDSCs on ex vivo stimulated T cell proliferation was NADPH oxidase-independent. In contrast to other tumor-bearing mouse models, our results show that MDSC accumulation and immunosuppression in syngeneic epithelial ovarian cancer is NADPH oxidase-independent. We speculate that factors inherent to the tumor, tumor microenvironment, or both determine the specific requirement for NADPH oxidase in MDSC accumulation and function.

  4. Functional Analysis of In-frame Indel ARID1A Mutations Reveals New Regulatory Mechanisms of Its Tumor Suppressor Functions

    Directory of Open Access Journals (Sweden)

    Bin Guan

    2012-10-01

    Full Text Available AT-rich interactive domain 1A (ARID1A has emerged as a new tumor suppressor in which frequent somatic mutations have been identified in several types of human cancers. Although most ARID1A somatic mutations are frame-shift or nonsense mutations that contribute to mRNA decay and loss of protein expression, 5% of ARID1A mutations are in-frame insertions or deletions (indels that involve only a small stretch of peptides. Naturally occurring in-frame indel mutations provide unique and useful models to explore the biology and regulatory role of ARID1A. In this study, we analyzed indel mutations identified in gynecological cancers to determine how these mutations affect the tumor suppressor function of ARID1A. Our results demonstrate that all in-frame mutants analyzed lost their ability to inhibit cellular proliferation or activate transcription of CDKN1A, which encodes p21, a downstream effector of ARID1A. We also showed that ARID1A is a nucleocytoplasmic protein whose stability depends on its subcellular localization. Nuclear ARID1A is less stable than cytoplasmic ARID1A because ARID1A is rapidly degraded by the ubiquitin-proteasome system in the nucleus. In-frame deletions affecting the consensus nuclear export signal reduce steady-state protein levels of ARID1A. This defect in nuclear exportation leads to nuclear retention and subsequent degradation. Our findings delineate a mechanism underlying the regulation of ARID1A subcellular distribution and protein stability and suggest that targeting the nuclear ubiquitin-proteasome system can increase the amount of the ARID1A protein in the nucleus and restore its tumor suppressor functions.

  5. Grape seed proanthocyanidins reactivate silenced tumor suppressor genes in human skin cancer cells by targeting epigenetic regulators.

    Science.gov (United States)

    Vaid, Mudit; Prasad, Ram; Singh, Tripti; Jones, Virginia; Katiyar, Santosh K

    2012-08-15

    Grape seed proanthocyanidins (GSPs) have been shown to have anti-skin carcinogenic effects in in vitro and in vivo models. However, the precise epigenetic molecular mechanisms remain unexplored. This study was designed to investigate whether GSPs reactivate silenced tumor suppressor genes following epigenetic modifications in skin cancer cells. For this purpose, A431 and SCC13 human squamous cell carcinoma cell lines were used as in vitro models. The effects of GSPs on DNA methylation, histone modifications and tumor suppressor gene expressions were studied in these cell lines using enzyme activity assays, western blotting, dot-blot analysis and real-time polymerase chain reaction (RT-PCR). We found that treatment of A431 and SCC13 cells with GSPs decreased the levels of: (i) global DNA methylation, (ii) 5-methylcytosine, (iii) DNA methyltransferase (DNMT) activity and (iv) messenger RNA (mRNA) and protein levels of DNMT1, DNMT3a and DNMT3b in these cells. Similar effects were noted when these cancer cells were treated identically with 5-aza-2'-deoxycytidine, an inhibitor of DNA methylation. GSPs decreased histone deacetylase activity, increased levels of acetylated lysines 9 and 14 on histone H3 (H3-Lys 9 and 14) and acetylated lysines 5, 12 and 16 on histone H4, and reduced the levels of methylated H3-Lys 9. Further, GSP treatment resulted in re-expression of the mRNA and proteins of silenced tumor suppressor genes, RASSF1A, p16(INK4a) and Cip1/p21. Together, this study provides a new insight into the epigenetic mechanisms of GSPs and may have significant implications for epigenetic therapy in the treatment/prevention of skin cancers in humans. Copyright © 2012 Elsevier Inc. All rights reserved.

  6. A Catalog of Genes Homozygously Deleted in Human Lung Cancer and the Candidacy of PTPRD as a Tumor Suppressor Gene

    Science.gov (United States)

    Kohno, Takashi; Otsuka, Ayaka; Girard, Luc; Sato, Masanori; Iwakawa, Reika; Ogiwara, Hideaki; Sanchez-Cespedes, Montse; Minna, John D.; Yokota, Jun

    2010-01-01

    A total of 176 genes homozygously deleted in human lung cancer were identified by DNA array-based whole genome scanning of 52 lung cancer cell lines and subsequent genomic PCR in 74 cell lines, including the 52 cell lines scanned. One or more exons of these genes were homozygously deleted in one (1%) to 20 (27%) cell lines. These genes included known tumor suppressor genes, e.g., CDKN2A/p16, RB1, and SMAD4, and candidate tumor suppressor genes whose hemizygous or homozygous deletions were reported in several types of human cancers, such as FHIT, KEAP1, and LRP1B/LRP-DIP. CDKN2A/p16 and p14ARF located in 9p21 were most frequently deleted (20/74, 27%). The PTPRD gene was most frequently deleted (8/74, 11%) among genes mapping to regions other than 9p21. Somatic mutations, including a nonsense mutation, of the PTPRD gene were detected in 8/74 (11%) of cell lines and 4/95 (4%) of surgical specimens of lung cancer. Reduced PTPRD expression was observed in the majority (>80%) of cell lines and surgical specimens of lung cancer. Therefore, PTPRD is a candidate tumor suppressor gene in lung cancer. Microarray-based expression profiling of 19 lung cancer cell lines also indicated that some of the 176 genes, such as KANK and ADAMTS1, are preferentially inactivated by epigenetic alterations. Genetic/epigenetic as well as functional studies of these 176 genes will increase our understanding of molecular mechanisms behind lung carcinogenesis. PMID:20073072

  7. RGS6 is an essential tumor suppressor that prevents bladder carcinogenesis by promoting p53 activation and DNMT1 downregulation.

    Science.gov (United States)

    Yang, Jianqi; Platt, Lance T; Maity, Biswanath; Ahlers, Katelin E; Luo, Zili; Lin, Zhibo; Chakravarti, Bandana; Ibeawuchi, Stella-Rita; Askeland, Ryan W; Bondaruk, Jolanta; Czerniak, Bogdan A; Fisher, Rory A

    2016-10-25

    Urinary bladder cancer (UBC) is largely caused by exposure to toxic chemicals including those in cigarette smoke (i.e. BBN). An activating SNP in RGS6 is associated with a pronounced reduction in UBC risk, especially among smokers. However, the mechanism underlying this reduction remains unknown. Here we demonstrate that RGS6 is robustly expressed in human urothelium, where urothelial cell carcinoma originates, and is downregulated in human UBC. Utilizing RGS6-/- mice we interrogated a possible role for RGS6 as a tumor suppressor using the BBN-induced bladder carcinogenesis model that closely recapitulates human disease. As in humans, RGS6 is robustly expressed in mouse urothelium. RGS6 loss dramatically accelerates BBN-induced bladder carcinogenesis, with RGS6-/- mice consistently displaying more advanced pathological lesions than RGS6+/+ mice. Furthermore, BBN treatment promotes urothelial RGS6 mRNA and protein downregulation. RGS6 loss impairs p53 activation and promotes aberrant accumulation of oncogenic protein DNMT1 in urothelium. Tumor suppressor RASSF1A, a DNMT1-regulated gene, is also silenced, likely via methylation of its promoter during BBN exposure. We hypothesize that this BBN-induced RGS6 loss represents a critical hit in UBC as it irrevocably impairs the anti-proliferative actions of the ATM/p53 and RASSF1A pathways. Consistent with these findings, RGS6-/- mice treated with CP-31398, a p53-stablizing agent, and/or 5-Aza, a DNMT1 inhibitor, are protected from BBN-induced tumorigenesis. Together, our data identify RGS6 as a master tumor suppressor modulating two critical signaling pathways that are often dysregulated in UBC; therefore, RGS6 represents a potential novel biomarker for UBC diagnosis/prognosis and an appealing new target in its treatment.

  8. miR-339-5p regulates the p53 tumor-suppressor pathway by targeting MDM2

    DEFF Research Database (Denmark)

    Jansson, M D; Djodji Damas, Nkerorema; Lees, M

    2014-01-01

    MicroRNAs (miRNAs) regulate many key cancer-relevant pathways and may themselves possess oncogenic or tumor-suppressor functions. Consequently, miRNA dysregulation has been shown to be a prominent feature in many human cancers. The p53 tumor suppressor acts as a negative regulator of cell...... proliferation in response to stress and represents the most commonly lost and mutated gene in human cancers. The function of p53 is inhibited by the MDM2 oncoprotein. Using a high-throughput screening approach, we identified miR-339-5p as a regulator of the p53 pathway. We demonstrate that this regulation...... inhibition of miR-339-5p function perturbs the p53 response in cancer cells, allowing an increased proliferation rate. In addition, miR-339-5p expression is downregulated in tumors harboring wild-type TP53, suggesting that reduction of miR-339-5p level helps to suppress the p53 response in p53-competent...

  9. The retinoblastoma protein: a master tumor suppressor acts as a link between cell cycle and cell adhesion

    Directory of Open Access Journals (Sweden)

    Engel BE

    2014-12-01

    Full Text Available Brienne E Engel,1 W Douglas Cress,1 Pedro G Santiago-Cardona2 1Molecular Oncology Program, H Lee Moffitt Cancer Center and Research Institute, Tampa, FL, USA; 2Department of Biochemistry, Ponce School of Medicine, Ponce, Puerto Rico, USA Abstract: RB1 was the first tumor suppressor gene discovered. Over 4 decades of work have revealed that the Rb protein (Rb is a master regulator of biological pathways influencing virtually every aspect of intrinsic cell fate including cell growth, cell-cycle checkpoints, differentiation, senescence, self-renewal, replication, genomic stability, and apoptosis. While these many processes may account for a significant portion of RB1's potency as a tumor suppressor, a small but growing stream of evidence suggests that RB1 also significantly influences how a cell interacts with its environment, including cell-to-cell and cell-to-extracellular matrix interactions. This review will highlight Rb’s role in the control of cell adhesion and how alterations in the adhesive properties of tumor cells may drive the deadly process of metastasis. Keywords: cadherin, integrin, Rb, cancer, aggressiveness, metastasis

  10. Genetic analysis of the Kirsten-ras-revertant 1 gene: Potentiation of its tumor suppressor activity by specific point mutations

    Energy Technology Data Exchange (ETDEWEB)

    Kitayama, Hitoshi (Institute of Physical and Chemical Research, Ibaraki (Japan) Univ. of Tsukuba, Ibaraki (Japan)); Matsuzaki, Tomoko; Ikawa, Yoji; Noda, Makoto (Institute of Physical and Chemical Research, Ibaraki (Japan))

    1990-06-01

    Kirsten-ras-revertant 1 (Krev-1) cDNA encodes a ras-related protein and exhibits an activity of inducing flat revertants at certain frequencies (2-5% of total transfectants) when introduced into a v-K-ras-transformed mouse NIH 3T3 cell line, DT. Toward understanding the mechanism of action of Krev-1 protein, the authors constructed a series of point mutants of Krev-1 cDNA and tested their biological activities in DT cells and HT1080 human fibrosarcoma cells harboring the activated N-ras gene. Substitutions of the amino acid residues in the putative guanine nucleotide-binding regions (Asp{sup 17} and Asn{sup 116}), in the putative effector-binding domain (residue 38), at the putative acylation site (Cys{sup 181}), and at the unique Thr{sup 61} all decreased the transformation suppressor activity. On the other hand, substitutions such as Gly{sup 12} to Val{sup 12} and Gln{sup 63} to Glu{sup 63} were found to significantly increase the transformation suppressor/tumor suppressor activity of Krev-1. These findings are consistent with the idea that Krev-1 protein is regulated like many other G proteins by the guanine triphosphate/guanine diphosphate-exchange mechanism probably in response to certain negative growth-regulatory signals.

  11. Grape seed proanthocyanidins reactivate silenced tumor suppressor genes in human skin cancer cells by targeting epigenetic regulators

    Energy Technology Data Exchange (ETDEWEB)

    Vaid, Mudit; Prasad, Ram; Singh, Tripti; Jones, Virginia [Department of Dermatology, University of Alabama at Birmingham, Birmingham, AL 35294 (United States); Katiyar, Santosh K., E-mail: skatiyar@uab.edu [Birmingham Veterans Affairs Medical Center, Birmingham, AL 35294 (United States); Department of Dermatology, University of Alabama at Birmingham, Birmingham, AL 35294 (United States); Comprehensive Cancer Center, University of Alabama at Birmingham, Birmingham, AL 35294 (United States)

    2012-08-15

    Grape seed proanthocyanidins (GSPs) have been shown to have anti-skin carcinogenic effects in in vitro and in vivo models. However, the precise epigenetic molecular mechanisms remain unexplored. This study was designed to investigate whether GSPs reactivate silenced tumor suppressor genes following epigenetic modifications in skin cancer cells. For this purpose, A431 and SCC13 human squamous cell carcinoma cell lines were used as in vitro models. The effects of GSPs on DNA methylation, histone modifications and tumor suppressor gene expressions were studied in these cell lines using enzyme activity assays, western blotting, dot-blot analysis and real-time polymerase chain reaction (RT-PCR). We found that treatment of A431 and SCC13 cells with GSPs decreased the levels of: (i) global DNA methylation, (ii) 5-methylcytosine, (iii) DNA methyltransferase (DNMT) activity and (iv) messenger RNA (mRNA) and protein levels of DNMT1, DNMT3a and DNMT3b in these cells. Similar effects were noted when these cancer cells were treated identically with 5-aza-2′-deoxycytidine, an inhibitor of DNA methylation. GSPs decreased histone deacetylase activity, increased levels of acetylated lysines 9 and 14 on histone H3 (H3-Lys 9 and 14) and acetylated lysines 5, 12 and 16 on histone H4, and reduced the levels of methylated H3-Lys 9. Further, GSP treatment resulted in re-expression of the mRNA and proteins of silenced tumor suppressor genes, RASSF1A, p16{sup INK4a} and Cip1/p21. Together, this study provides a new insight into the epigenetic mechanisms of GSPs and may have significant implications for epigenetic therapy in the treatment/prevention of skin cancers in humans. -- Highlights: ►Epigenetic modulations have been shown to have a role in cancer risk. ►Proanthocyanidins decrease the levels of DNA methylation and histone deacetylation. ►Proanthocyanidins inhibit histone deacetylase activity in skin cancer cells. ►Proanthocyanidins reactivate tumor suppressor genes in skin

  12. Human Immunodeficiency Virus Type 1 Nef Binds to Tumor Suppressor p53 and Protects Cells against p53-Mediated Apoptosis

    OpenAIRE

    2002-01-01

    The nef gene product of human immunodeficiency virus type 1 (HIV-1) is important for the induction of AIDS, and key to its function is its ability to manipulate T-cell function by targeting cellular signal transduction proteins. We reported that Nef coprecipitates a multiprotein complex from cells which contains tumor suppressor protein p53. We now show that Nef interacts directly with p53. Binding assays showed that an N-terminal, 57-residue fragment of Nef (Nef 1-57) contains the p53-bindin...

  13. SIGNALING TO THE P53 TUMOR SUPPRESSOR THROUGH PATHWAYS ACTIVATED BY GENOTOXIC AND NON-GENOTOXIC STRESSES.

    Energy Technology Data Exchange (ETDEWEB)

    ANDERSON,C.W.APPELLA,E.

    2002-07-01

    The p53 tumor suppressor is a tetrameric transcription factor that is post-translational modified at {approx}18 different sites by phosphorylation, acetylation, or sumoylation in response to various cellular stress conditions. Specific posttranslational modifications, or groups of modifications, that result from the activation of different stress-induced signaling pathways are thought to modulate p53 activity to regulate cell fate by inducing cell cycle arrest, apoptosis, or cellular senescence. Here we review the posttranslational modifications to p53 and the pathways that produce them in response to both genotoxic and non-genotoxic stresses.

  14. A tumor suppressor C53 protein antagonizes checkpoint kinases to promote cyclin-dependent kinase 1 activation

    OpenAIRE

    Jiang, Hai; Wu, Jianchun; He, Chen; Yang, Wending; Li, Honglin

    2009-01-01

    Cyclin dependent kinase 1 (Cdk1)/cyclin B1 complex is the driving force for mitotic entry, and its activation is tightly regulated by the G2/M checkpoint. We originally reported that a novel protein C53 (also known as Cdk5rap3 and LZAP) potentiates DNA damage-induced cell death by modulating the G2/M checkpoint (1). More recently, Wang et al (2007) found that C53/LZAP may function as a tumor suppressor via inhibiting NF-κB signaling (2). We report here identification of C53 protein as a novel...

  15. The wip1 phosphatase (PPM1D) antagonizes activation of the CHK2 tumor suppressor kinase

    Energy Technology Data Exchange (ETDEWEB)

    Manet, Oliva-Trastoy; Berthonaud, V.; Chevalier, A.; Ducrot, C.; Marsolier-Kergoat, M.C.; Mann, C.; Leteurtre, F. [CEA Saclay, DSV, DBJC, SBGM, Lab. du Controle du Cycle Cellulaire, 91 - Gif-sur-Yvette (France)

    2006-07-01

    The DNA checkpoints are signal transduction pathways that sense DNA damage and coordinate various responses such as cell cycle arrests, DNA repair or cell death. These pathways are particularly well conserved in eukaryotes and the family of the 'Checkpoint Kinases 2' genes (or CHK2) plays a major role in them. This family includes the Rad53 protein of the yeast Saccharomyces cerevisiae and its Chk2 human homologue. Rad53 plays a central part in DNA checkpoint: rad53d mutants (whose RAD53 gene has been deleted) are hypersensitive to all genotoxic stresses. Mice Chk2-1- cells are defective in the G1, the intra-S, and the G2/M checkpoints. Mutations in CHK2 have been associated to many forms o f cancer, either sporadic or hereditary which demonstrates Chk2 tumor suppressor function. Chk2 proteins are characterized by several conserved elements: (i) an N-terminal domain with a series of SQ/TQ motifs, preferential phosphorylation sites for the ATM/ATR kinases, (ii) an FHA domain (ForkHead Associated) that binds specifically to phosphorylated residues within TXXY motifs (with the Y residue depending on the FHA domain and conferring an extra specificity) and (iii) a kinase domain including an activation loop. The Chk2 protein is activated by phosphorylation of its threonine T68, mainly by ATM, upon DNA double-strand breaks. This phosphorylation allows for the homo-dimerization of Chk2 through the binding of phospho-T68 from one molecule to the FHA domain of another molecule. It results in trans auto-phosphorylations, especially at threonines T383 and T387 in the activation T-loop. Fully active Chk2 becomes monomeric and, diffusing through the whole nucleus, phosphorylates its targets (CDC25 A and CDC25C/cell cycle arrest; p53, E2F, PML/apoptosis; BRCA2/DNA repair). Chk2/Rad53 inactivation occurs in two cases: once the DNA lesions have been repaired (it is called recovery) or, under certain conditions, in the presence of unrepaired DNA damage (it is then called

  16. Cancer cell specific cytotoxic gene expression mediated by ARF tumor suppressor promoter constructs

    Energy Technology Data Exchange (ETDEWEB)

    Kurayoshi, Kenta [Department of Bioscience, School of Science and Technology, Kwansei Gakuin University, 2-1 Gakuen, Sanda, Hyogo 669-1337 (Japan); Ozono, Eiko [Centre for Molecular Oncology, Barts Cancer Institute, Queen Mary, University of London, John Vane Science Centre, Charterhouse Square, London EC1M 6BQ (United Kingdom); Iwanaga, Ritsuko; Bradford, Andrew P. [Department of Obstetrics and Gynecology, University of Colorado School of Medicine, Anschutz Medical Campus, 12800 East 19th Avenue, Aurora, CO 80045 (United States); Komori, Hideyuki [Center for Stem Cell Biology, Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109 (United States); Ohtani, Kiyoshi, E-mail: btm88939@kwansei.ac.jp [Department of Bioscience, School of Science and Technology, Kwansei Gakuin University, 2-1 Gakuen, Sanda, Hyogo 669-1337 (Japan)

    2014-07-18

    Highlights: • ARF promoter showed higher responsiveness to deregulated E2F activity than the E2F1 promoter. • ARF promoter showed higher cancer cell-specificity than E2F1 promoter to drive gene expression. • HSV-TK driven by ARF promoter showed higher cancer cell-specific cytotoxicity than that driven by E2F1 promoter. - Abstract: In current cancer treatment protocols, such as radiation and chemotherapy, side effects on normal cells are major obstacles to radical therapy. To avoid these side effects, a cancer cell-specific approach is needed. One way to specifically target cancer cells is to utilize a cancer specific promoter to express a cytotoxic gene (suicide gene therapy) or a viral gene required for viral replication (oncolytic virotherapy). For this purpose, the selected promoter should have minimal activity in normal cells to avoid side effects, and high activity in a wide variety of cancers to obtain optimal therapeutic efficacy. In contrast to the AFP, CEA and PSA promoters, which have high activity only in a limited spectrum of tumors, the E2F1 promoter exhibits high activity in wide variety of cancers. This is based on the mechanism of carcinogenesis. Defects in the RB pathway and activation of the transcription factor E2F, the main target of the RB pathway, are observed in almost all cancers. Consequently, the E2F1 promoter, which is mainly regulated by E2F, has high activity in wide variety of cancers. However, E2F is also activated by growth stimulation in normal growing cells, suggesting that the E2F1 promoter may also be highly active in normal growing cells. In contrast, we found that the tumor suppressor ARF promoter is activated by deregulated E2F activity, induced by forced inactivation of pRB, but does not respond to physiological E2F activity induced by growth stimulation. We also found that the deregulated E2F activity, which activates the ARF promoter, is detected only in cancer cell lines. These observations suggest that ARF promoter

  17. Direct transcriptional regulation of Bim by FoxO3a mediates STI571-induced apoptosis in Bcr-Abl-expressing cells

    NARCIS (Netherlands)

    Essafi, A.; Mattos, S.F. de; Hassen, Y.A.M.; Soeiro, I.; Mufti, G.J.; Thomas, N.S.B.; Medema, R.H.; Lam, E.W.-F.

    2005-01-01

    In this study, we have used the human BV173 and the mouse BaF3/Bcr-Abl-expressing cell lines as model systems to investigate the molecular mechanisms whereby STI571 and FoxO3a regulate Bim expression and apoptosis. FoxO3a lies downstream of Bcr-Abl signalling and is constitutively

  18. The Role of Tumor Metastases Suppressor Gene, Drg-1, in Breast Cancer

    Science.gov (United States)

    2009-03-01

    19q13.1 126, 127 EGF Cell proliferation, mitogenicity Breast, Prostate 4q25 128, 129 PDGF Embryological development Breast, Prostate 22q13.1 130, 131...results of their study also ruled out the possibility of BRMS1 upregulating expression of other metastasis suppressors, such as NM23, KAI1, KiSS1 or E

  19. Receptor FGFRL1 acts as a tumor suppressor in nude mice when overexpressed in HEK 293 Tet-On cells

    Science.gov (United States)

    Zhuang, Lei; Steinberg, Florian; Trueb, Beat

    2016-01-01

    Fibroblast growth factor receptor-like 1 (FGFRL1) is a transmembrane receptor that interacts with heparin and FGF ligands. In contrast to the classical FGF receptors, FGFR1 to FGFR4, it does not appear to affect cell growth and proliferation. In the present study, an inducible gene expression system was utilized in combination with a xenograft tumor model to investigate the effects of FGFRL1 on cell adhesion and tumor formation. It was determined that recombinant FGFRL1 promotes the adhesion of HEK 293 Tet-On® cells in vitro. Moreover, when such cells are induced to express FGFRL1ΔC they aggregate into huge clusters. If injected into nude mice, the cells form large tumors. Notably, this tumor growth is completely inhibited when the expression of FGFRL1 is induced. The forced expression of FGFRL1 in the tumor tissue may restore contact inhibition, thereby preventing growth of the cells in nude mice. The results of the present study demonstrate that FGFRL1 acts as a tumor suppressor similar to numerous other cell adhesion proteins. It is therefore likely that FGFRL1 functions as a regular cell-cell adhesion protein. PMID:28101211

  20. CHIP/Stub1 functions as a tumor suppressor and represses NF-κB-mediated signaling in colorectal cancer.

    Science.gov (United States)

    Wang, Yangmeng; Ren, Fangli; Wang, Yinyin; Feng, Yarui; Wang, Dianjun; Jia, Baoqing; Qiu, Ying; Wang, Shiyan; Yu, Jun; Sung, Joseph Jy; Xu, Jiake; Zeps, Nikolajs; Chang, Zhijie

    2014-05-01

    The carboxyl terminus of Hsc70-interacting protein (CHIP, also named Stub1), a U-box containing E3 ubiquitin ligase, is involved in degradation of certain oncogenic proteins. Recent studies indicated that CHIP suppresses tumor progression in human cancers by targeting Src-3, hypoxia inducible factor 1α, NF-κB, ErbB2 and c-Myc. Here, we report that CHIP was downregulated, predominantly, in the late stages of human colorectal cancer (CRC), and that the CHIP promoter was hypermethylated in CRC specimens. Overexpression of CHIP in HCT-116 cells resulted in impaired tumor growth in nude mice and decreased abilities of tumor cell migration and invasion. Conversely, depletion of CHIP in HCT-116 cells promoted tumor growth and increased tumor cell migration and invasion. CHIP was further found to negatively regulate NF-κB signaling in HCT-116 cells by promoting ubiquitination and degradation of p65, a subunit of the NF-κB complex. The suppressive effect of CHIP led to decreased expression of NF-κB-targeted oncogenes including Cyclin D1, c-Myc, MMP-2, VEGF and IL-8. We proposed that CHIP inhibits the malignancy of CRC cells, possibly through targeting NF-κB signaling. This study provides functional evidence for CHIP as a potential tumor suppressor in CRC, and CHIP expression may be a marker for stages of CRC.

  1. MST1 activation by curcumin mediates JNK activation, Foxo3a nuclear translocation and apoptosis in melanoma cells

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Teng, E-mail: tengyu33@yahoo.com [Department of Dermatology, Shandong Ji-ning No. 1 People’s Hospital, Shandong Province 272011 (China); Ji, Jiang [Department of Dermatology, The Second Hospital Affiliated of Soochow University, SuZhou, Jiangsu Province 215000 (China); Guo, Yong-li [Department of Oncology, Shandong Ji-ning No. 1 People’s Hospital, Shandong Province 272011 (China)

    2013-11-08

    Highlights: •Curcumin activates MST1 in melanoma cells. •MST1 mediates curcumin-induced apoptosis of melanoma cells. •ROS production is involved in curcumin-induced MST1 activation. •MST1 mediates curcumin-induced JNK activation in melanoma cells. •MST1 mediates curcumin-induced Foxo3a nuclear translocation and Bim expression. -- Abstract: Different groups including ours have shown that curcumin induces melanoma cell apoptosis, here we focused the role of mammalian Sterile 20-like kinase 1 (MST1) in it. We observed that curcumin activated MST1-dependent apoptosis in cultured melanoma cells. MST1 silencing by RNA interference (RNAi) suppressed curcumin-induced cell apoptosis, while MST1 over-expressing increased curcumin sensitivity. Meanwhile, curcumin induced reactive oxygen species (ROS) production in melanoma cells, and the ROS scavenger, N-acetyl-cysteine (NAC), almost blocked MST1 activation to suggest that ROS might be required for MST1 activation by curcumin. c-Jun N-terminal protein kinase (JNK) activation by curcumin was dependent on MST1, since MST1 inhibition by RNAi or NAC largely inhibited curcumin-induced JNK activation. Further, curcumin induced Foxo3 nuclear translocation and Bim-1 (Foxo3 target gene) expression in melanoma cells, such an effect by curcumin was inhibited by MST1 RNAi. In conclusion, we suggested that MST1 activation by curcumin mediates JNK activation, Foxo3a nuclear translocation and apoptosis in melanoma cells.

  2. Crystal structure of the human FOXO3a-DBD/DNA complex suggests the effects of post-translational modification.

    Science.gov (United States)

    Tsai, Kuang-Lei; Sun, Yuh-Ju; Huang, Cheng-Yang; Yang, Jer-Yen; Hung, Mien-Chie; Hsiao, Chwan-Deng

    2007-01-01

    FOXO3a is a transcription factor of the FOXO family. The FOXO proteins participate in multiple signaling pathways, and their transcriptional activity is regulated by several post-translational mechanisms, including phosphorylation, acetylation and ubiquitination. Because these post-translational modification sites are located within the C-terminal basic region of the FOXO DNA-binding domain (FOXO-DBD), it is possible that these post-translational modifications could alter the DNA-binding characteristics. To understand how FOXO mediate transcriptional activity, we report here the 2.7 A crystal structure of the DNA-binding domain of FOXO3a (FOXO3a-DBD) bound to a 13-bp DNA duplex containing a FOXO consensus binding sequence (GTAAACA). Based on a unique structural feature in the C-terminal region and results from biochemical and mutational studies, our studies may explain how FOXO-DBD C-terminal phosphorylation by protein kinase B (PKB) or acetylation by cAMP-response element binding protein (CBP) can attenuate the DNA-binding activity and thereby reduce transcriptional activity of FOXO proteins. In addition, we demonstrate that the methyl groups of specific thymine bases within the consensus sequence are important for FOXO3a-DBD recognition of the consensus binding site.

  3. The milk protein α-casein functions as a tumor suppressor via activation of STAT1 signaling, effectively preventing breast cancer tumor growth and metastasis.

    Science.gov (United States)

    Bonuccelli, Gloria; Castello-Cros, Remedios; Capozza, Franco; Martinez-Outschoorn, Ubaldo E; Lin, Zhao; Tsirigos, Aristotelis; Xuanmao, Jiao; Whitaker-Menezes, Diana; Howell, Anthony; Lisanti, Michael P; Sotgia, Federica

    2012-11-01

    Here, we identified the milk protein α-casein as a novel suppressor of tumor growth and metastasis. Briefly, Met-1 mammary tumor cells expressing α-casein showed a ~5-fold reduction in tumor growth and a near 10-fold decrease in experimental metastasis. To identify the molecular mechanism(s), we performed genome-wide transcriptional profiling. Interestingly, our results show that α-casein upregulates gene transcripts associated with interferon/STAT1 signaling and downregulates genes associated with "stemness." These findings were validated by immunoblot and FACS analysis, which showed the upregulation and hyperactivation of STAT1 and a decrease in the number of CD44(+) "cancer stem cells." These gene signatures were also able to predict clinical outcome in human breast cancer patients. Thus, we conclude that a lactation-based therapeutic strategy using recombinant α-casein would provide a more natural and non-toxic approach to the development of novel anticancer therapies.

  4. ERK5/BMK1 Is a Novel Target of the Tumor Suppressor VHL: Implication in Clear Cell Renal Carcinoma12

    Science.gov (United States)

    Arias-González, Laura; Moreno-Gimeno, Inmaculada; del Campo, Antonio Rubio; Serrano-Oviedo, Leticia; Valero, María Llanos; Esparís-Ogando, Azucena; de la Cruz-Morcillo, Miguel Ángel; Melgar-Rojas, Pedro; García-Cano, Jesús; Cimas, Francisco José; Hidalgo, María José Ruiz; Prado, Alfonso; Callejas-Valera, Juan Luis; Nam-Cha, Syong Hyun; Giménez-Bachs, José Miguel; Salinas-Sánchez, Antonio S; Pandiella, Atanasio; del Peso, Luis; Sánchez-Prieto, Ricardo

    2013-01-01

    Extracellular signal-regulated kinase 5 (ERK5), also known as big mitogen-activated protein kinase (MAPK) 1, is implicated in a wide range of biologic processes, which include proliferation or vascularization. Here, we show that ERK5 is degraded through the ubiquitin-proteasome system, in a process mediated by the tumor suppressor von Hippel-Lindau (VHL) gene, through a prolyl hydroxylation-dependent mechanism. Our conclusions derive from transient transfection assays in Cos7 cells, as well as the study of endogenous ERK5 in different experimental systems such as MCF7, HMEC, or Caki-2 cell lines. In fact, the specific knockdown of ERK5 in pVHL-negative cell lines promotes a decrease in proliferation and migration, supporting the role of this MAPK in cellular transformation. Furthermore, in a short series of fresh samples from human clear cell renal cell carcinoma, high levels of ERK5 correlate with more aggressive and metastatic stages of the disease. Therefore, our results provide new biochemical data suggesting that ERK5 is a novel target of the tumor suppressor VHL, opening a new field of research on the role of ERK5 in renal carcinomas. PMID:23730213

  5. The BRCA1 Tumor Suppressor Binds to Inositol 1,4,5-Trisphosphate Receptors to Stimulate Apoptotic Calcium Release*

    Science.gov (United States)

    Hedgepeth, Serena C.; Garcia, M. Iveth; Wagner, Larry E.; Rodriguez, Ana M.; Chintapalli, Sree V.; Snyder, Russell R.; Hankins, Gary D. V.; Henderson, Beric R.; Brodie, Kirsty M.; Yule, David I.; van Rossum, Damian B.; Boehning, Darren

    2015-01-01

    The inositol 1,4,5-trisphosphate receptor (IP3R) is a ubiquitously expressed endoplasmic reticulum (ER)-resident calcium channel. Calcium release mediated by IP3Rs influences many signaling pathways, including those regulating apoptosis. IP3R activity is regulated by protein-protein interactions, including binding to proto-oncogenes and tumor suppressors to regulate cell death. Here we show that the IP3R binds to the tumor suppressor BRCA1. BRCA1 binding directly sensitizes the IP3R to its ligand, IP3. BRCA1 is recruited to the ER during apoptosis in an IP3R-dependent manner, and, in addition, a pool of BRCA1 protein is constitutively associated with the ER under non-apoptotic conditions. This is likely mediated by a novel lipid binding activity of the first BRCA1 C terminus domain of BRCA1. These findings provide a mechanistic explanation by which BRCA1 can act as a proapoptotic protein. PMID:25645916

  6. Retinoid-induced expression and activity of an immediate early tumor suppressor gene in vascular smooth muscle cells.

    Directory of Open Access Journals (Sweden)

    Jeffrey W Streb

    Full Text Available Retinoids are used clinically to treat a number of hyper-proliferative disorders and have been shown in experimental animals to attenuate vascular occlusive diseases, presumably through nuclear receptors bound to retinoic acid response elements (RARE located in target genes. Here, we show that natural or synthetic retinoids rapidly induce mRNA and protein expression of a specific isoform of A-Kinase Anchoring Protein 12 (AKAP12β in cultured smooth muscle cells (SMC as well as the intact vessel wall. Expression kinetics and actinomycin D studies indicate Akap12β is a retinoid-induced, immediate-early gene. Akap12β promoter analyses reveal a conserved RARE mildly induced with atRA in a region that exhibits hyper-acetylation. Immunofluorescence microscopy and protein kinase A (PKA regulatory subunit overlay assays in SMC suggest a physical association between AKAP12β and PKA following retinoid treatment. Consistent with its designation as a tumor suppressor, inducible expression of AKAP12β attenuates SMC growth in vitro. Further, immunohistochemistry studies establish marked decreases in AKAP12 expression in experimentally-injured vessels of mice as well as atheromatous lesions in humans. Collectively, these results demonstrate a novel role for retinoids in the induction of an AKAP tumor suppressor that blocks vascular SMC growth thus providing new molecular insight into how retiniods may exert their anti-proliferative effects in the injured vessel wall.

  7. Dissecting functions of the retinoblastoma tumor suppressor and the related pocket proteins by integrating genetic, cell biology, and electrophoretic techniques

    DEFF Research Database (Denmark)

    Hansen, Klaus; Lukas, J; Holm, K

    1999-01-01

    The members of the 'pocket protein' family, comprising the retinoblastoma tumor suppressor (pRB) and its relatives, p107 and p130, negatively regulate cell proliferation and modulate fundamental biological processes including embryonic development, differentiation, homeostatic tissue renewal, and......RB family, and show examples of how integration of genetic, cell biology, and a range of electrophoretic approaches help to advance our understanding of the biological roles played by the pocket proteins in both normal and cancer cells.......The members of the 'pocket protein' family, comprising the retinoblastoma tumor suppressor (pRB) and its relatives, p107 and p130, negatively regulate cell proliferation and modulate fundamental biological processes including embryonic development, differentiation, homeostatic tissue renewal......, and defense against cancer. The large, multidomain pocket proteins act by binding a plethora of cell fate-determining and growth-stimulatory proteins, the most prominent of which are the E2F/DP transcription factors. These protein-protein interactions are in turn regulated by carefully orchestrated...

  8. Phytochemical Compositions of Immature Wheat Bran, and Its Antioxidant Capacity, Cell Growth Inhibition, and Apoptosis Induction through Tumor Suppressor Gene

    Directory of Open Access Journals (Sweden)

    Mi Jeong Kim

    2016-09-01

    Full Text Available The purpose of this study was to investigate the phytochemical compositions and antioxidant capacity, cell growth inhibition, and apoptosis induction in extracts of immature wheat bran. Immature wheat bran (IWB was obtained from immature wheat harvested 10 days earlier than mature wheat. The phytochemical compositions of bran extract samples were analyzed by ultra-high performance liquid chromatography. The total ferulic acid (3.09 mg/g and p-coumaric acid (75 µg/g in IWB were significantly higher than in mature wheat bran (MWB, ferulic acid: 1.79 mg/g; p-coumaric acid: 55 µg/g. The oxygen radical absorbance capacity (ORAC: 327 µM Trolox equivalents (TE/g and cellular antioxidant activity (CAA: 4.59 µM Quercetin equivalents (QE/g of the IWB were higher than those of the MWB (ORAC: 281 µM TE/g; CAA: 0.63 µM QE/g. When assessing cell proliferation, the IWB extracts resulted in the lowest EC50 values against HT-29 (18.9 mg/mL, Caco-2 (7.74 mg/mL, and HeLa cells (8.17 mg/mL among bran extract samples. Additionally, the IWB extracts increased the gene expression of p53 and PTEN (tumor suppressor genes in HT-29 cells, indicating inhibited cell growth and induced apoptosis through tumor suppressor genes.

  9. ERK5/BMK1 Is a Novel Target of the Tumor Suppressor VHL: Implication in Clear Cell Renal Carcinoma

    Directory of Open Access Journals (Sweden)

    Laura Arias-González

    2013-06-01

    Full Text Available Extracellular signal-regulated kinase 5 (ERK5, also known as big mitogen-activated protein kinase (MAPK 1, is implicated in a wide range of biologic processes, which include proliferation or vascularization. Here, we show that ERK5 is degraded through the ubiquitin-proteasome system, in a process mediated by the tumor suppressor von Hippel-Lindau (VHL gene, through a prolyl hydroxylation-dependent mechanism. Our conclusions derive from transient transfection assays in Cos7 cells, as well as the study of endogenous ERK5 in different experimental systems such as MCF7, HMEC, or Caki-2 cell lines. In fact, the specific knockdown of ERK5 in pVHL-negative cell lines promotes a decrease in proliferation and migration, supporting the role of this MAPK in cellular transformation. Furthermore, in a short series of fresh samples from human clear cell renal cell carcinoma, high levels of ERK5 correlate with more aggressive and metastatic stages of the disease. Therefore, our results provide new biochemical data suggesting that ERK5 is a novel target of the tumor suppressor VHL, opening a new field of research on the role of ERK5 in renal carcinomas.

  10. LARG at chromosome 11q23 has functional characteristics of a tumor suppressor in human breast and colorectal cancer.

    Science.gov (United States)

    Ong, D C T; Ho, Y M; Rudduck, C; Chin, K; Kuo, W-L; Lie, D K H; Chua, C L M; Tan, P H; Eu, K W; Seow-Choen, F; Wong, C Y; Hong, G S; Gray, J W; Lee, A S G

    2009-11-26

    Deletion of 11q23-q24 is frequent in a diverse variety of malignancies, including breast and colorectal carcinoma, implicating the presence of a tumor suppressor gene at that chromosomal region. We examined a 6-Mb region on 11q23 by high-resolution deletion mapping, using both loss of heterozygosity analysis and customized microarray comparative genomic hybridization. LARG (leukemia-associated Rho guanine-nucleotide exchange factor) (also called ARHGEF12), identified from the analysed region, is frequently underexpressed in breast and colorectal carcinomas with a reduced expression observed in all breast cancer cell lines (n=11), in 12 of 38 (32%) primary breast cancers, 5 of 10 (50%) colorectal cell lines and in 20 of 37 (54%) primary colorectal cancers. Underexpression of the LARG transcript was significantly associated with genomic loss (P=0.00334). Hypermethylation of the LARG promoter was not detected in either breast or colorectal cancer, and treatment of four breast and four colorectal cancer cell lines with 5-aza-2'-deoxycytidine and/or trichostatin A did not result in a reactivation of LARG. Enforced expression of LARG in breast and colorectal cancer cells by stable transfection resulted in reduced cell proliferation and colony formation, as well as in a markedly slower cell migration rate in colorectal cancer cells, providing functional evidence for LARG as a candidate tumor suppressor gene.

  11. CONVERGENCE OF P53 AND TGFβ SIGNALING ON ACTIVATING EXPRESSION OF THE TUMOR SUPPRESSOR GENE MASPIN IN MAMMARY EPITHELIAL CELLS

    Science.gov (United States)

    Wang, Shizhen Emily; Narasanna, Archana; Whitell, Corbin W.; Wu, Frederick Y.; Friedman, David B.; Arteaga, Carlos L.

    2014-01-01

    Using two-dimensional difference gel electrophoresis, we identified the tumor suppressor gene maspin as a TGFβ target gene in human mammary epithelial cells. TGFβ upregulates maspin expression both at the RNA and protein levels. This upregulation required Smad2/3 function and intact p53 binding elements in the maspin promoter. DNA affinity immunoblot and chromatin immunoprecipitation (ChIP) revealed the presence of both Smads and p53 at the maspin promoter in TGFβ-treated cells, suggesting that both transcription factors cooperate to induce maspin transcription. TGFβ did not activate maspin-luciferase reporter in p53-mutant MDA-MB-231 breast cancer cells, which exhibit methylation of the endogenous maspin promoter. Expression of ectopic p53, however, restored ligand-induced association of Smad2/3 with a transfected maspin promoter. Stable transfection of maspin inhibited basal and TGFβ-stimulated MDA-MB-231 cell motility. Finally, knockdown of endogenous maspin in p53 wild-type MCF10A/HER2 cells enhanced basal and TGFβ-stimulated motility. Taken together, these data support cooperation between the p53 and TGFβ tumor suppressor pathways in the induction of maspin expression, thus leading to inhibition of cell migration. PMID:17204482

  12. Reverse engineering of TLX oncogenic transcriptional networks identifies RUNX1 as tumor suppressor in T-ALL.

    Science.gov (United States)

    Della Gatta, Giusy; Palomero, Teresa; Perez-Garcia, Arianne; Ambesi-Impiombato, Alberto; Bansal, Mukesh; Carpenter, Zachary W; De Keersmaecker, Kim; Sole, Xavier; Xu, Luyao; Paietta, Elisabeth; Racevskis, Janis; Wiernik, Peter H; Rowe, Jacob M; Meijerink, Jules P; Califano, Andrea; Ferrando, Adolfo A

    2012-02-26

    The TLX1 and TLX3 transcription factor oncogenes have a key role in the pathogenesis of T cell acute lymphoblastic leukemia (T-ALL). Here we used reverse engineering of global transcriptional networks to decipher the oncogenic regulatory circuit controlled by TLX1 and TLX3. This systems biology analysis defined T cell leukemia homeobox 1 (TLX1) and TLX3 as master regulators of an oncogenic transcriptional circuit governing T-ALL. Notably, a network structure analysis of this hierarchical network identified RUNX1 as a key mediator of the T-ALL induced by TLX1 and TLX3 and predicted a tumor-suppressor role for RUNX1 in T cell transformation. Consistent with these results, we identified recurrent somatic loss-of-function mutations in RUNX1 in human T-ALL. Overall, these results place TLX1 and TLX3 at the top of an oncogenic transcriptional network controlling leukemia development, show the power of network analyses to identify key elements in the regulatory circuits governing human cancer and identify RUNX1 as a tumor-suppressor gene in T-ALL.

  13. VGLL4 functions as a new tumor suppressor in lung cancer by negatively regulating the YAP-TEAD transcriptional complex.

    Science.gov (United States)

    Zhang, Wenjing; Gao, Yijun; Li, Peixue; Shi, Zhubing; Guo, Tong; Li, Fei; Han, Xiangkun; Feng, Yan; Zheng, Chao; Wang, Zuoyun; Li, Fuming; Chen, Haiquan; Zhou, Zhaocai; Zhang, Lei; Ji, Hongbin

    2014-03-01

    Lung cancer is one of the most devastating diseases worldwide with high incidence and mortality. Hippo (Hpo) pathway is a conserved regulator of organ size in both Drosophila and mammals. Emerging evidence has suggested the significance of Hpo pathway in cancer development. In this study, we identify VGLL4 as a novel tumor suppressor in lung carcinogenesis through negatively regulating the formation of YAP-TEAD complex, the core component of Hpo pathway. Our data show that VGLL4 is frequently observed to be lowly expressed in both mouse and human lung cancer specimens. Ectopic expression of VGLL4 significantly suppresses the growth of lung cancer cells in vitro. More importantly, VGLL4 significantly inhibits lung cancer progression in de novo mouse model. We further find that VGLL4 inhibits the activity of the YAP-TEAD transcriptional complex. Our data show that VGLL4 directly competes with YAP in binding to TEADs and executes its growth-inhibitory function through two TDU domains. Collectively, our study demonstrates that VGLL4 is a novel tumor suppressor for lung cancer through negatively regulating the YAP-TEAD complex formation and thus the Hpo pathway.

  14. Aberrant large tumor suppressor 2 (LATS2) gene expression correlates with EGFR mutation and survival in lung adenocarcinomas

    Science.gov (United States)

    Luo, Susan Y.; Sit, Ko-Yung; Sihoe, Alan D.L.; Suen, Wai-Sing; Au, Wing-Kuk; Tang, Ximing; Ma, Edmond S.K.; Chan, Wai-Kong; Wistuba, Ignacio I.; Minna, John D.; Tsao, George S.W.; Lam, David C.L.

    2015-01-01

    Background Large tumor suppressor 2 (LATS2) gene is a putative tumor suppressor gene with potential roles in regulation of cell proliferation and apoptosis in lung cancer. The aim of this study is to explore the association of aberrant LATS2 expression with EGFR mutation and survival in lung adenocarcinoma (AD), and the effects of LATS2 silencing in both lung AD cell lines. Methods LATS2 mRNA and protein expression in resected lung AD were correlated with demographic characteristics, EGFR mutation and survival. LATS2-specific siRNA was transfected into four EGFR wild-type (WT) and three EGFR mutant AD cell lines and the changes in LATS2 expression and relevant signaling molecules before and after LATS2 knockdown were assayed. Results Fifty resected lung AD were included (M:F = 23:27, smokers:non-smokers = 19:31, EGFR mutant:wild-type = 21:29) with LATS2 mRNA levels showed no significant difference between gender, age, smoking and pathological stages while LATS2 immunohistochemical staining on an independent set of 79 lung AD showed similar trend. LATS2 mRNA level was found to be a significant independent predictor for survival status (disease-free survival RR = 0.217; p = 0.003; Overall survival RR = 0.238; p = 0.036). siRNA-mediated suppression of LATS2 expression resulted in augmentation of ERK phosphorylation in EGFR wild-type AD cell lines with high basal LATS2 expression, discriminatory modulation of Akt signaling between EGFR wild-type and mutant cells, and induction of p53 accumulation in AD cell lines with low baseline p53 levels. Conclusions LATS2 expression level is predictive of survival in patients with resected lung AD. LATS2 may modulate and contribute to tumor growth via different signaling pathways in EGFR mutant and wild-type tumors. PMID:24976335

  15. Tumor-associated methylation of the putative tumor suppressor AJAP1 gene and association between decreased AJAP1 expression and shorter survival in patients with glioma

    Institute of Scientific and Technical Information of China (English)

    David Cogdell; Woonbok Chung; Yuexin Liu; Matthew McDonald; Kenneth Aldape; Jean-Pierre J. Issa; Gregory N. Fuller; Wei Zhang

    2011-01-01

    Allelic loss of the short arm of chromosome 1 has been observed frequently in a wide spectrum of cancers, most frequently in oligodendroglioma. In our previous studies, we evaluated 177 oligodendroglial tumor samples and identified the AJAP1 gene (formerly Shrew1) in the consensus region of deletion.AJAP1 is a transmembrane protein found in adheren junctions and functions to inhibit glioma cell adhesion and migration. Whereas a putative tumor suppressor gene, we did not detect AJAP1 gene mutations. In subsequent studies, we found that AJAP1 was underexpressed in oligodendrogliomas relative to normal brain tissues. Bioinformatic analysis revealed the presence of CpG islands in the promoter of AJAP1.Methylation analysis of the AJAP1 promoter identified hypermethylation in 21% of oligodendrogliomas (n = 27), and the degree of methylation correlated with Iow levels of AJAP1 expression (P = 0.045). The AJAP1 promoter was also highly methylated in a wide spectrum of cell lines (n = 22), including cell lines of glioblastoma. Analysis of the National Cancer Institute's REMBRANDT dataset, which contains 343 glioma samples, indicated that Iow AJAP1 gene expression was associated with decreased survival. Thus,both genetic (gene deletion) and epigenetic alterations (promoter methylation) are likely mechanisms that inactivate the putative tumor suppressor AJAP1 in gliomas, which contributes to poor prognosis.

  16. Tumor-associated methylation of the putative tumor suppressor AJAP1 gene and association between decreased AJAP1 expression and shorter survival in patients with glioma.

    Science.gov (United States)

    Cogdell, David; Chung, Woonbok; Liu, Yuexin; McDonald, J Matthew; Aldape, Kenneth; Issa, Jean-Pierre J; Fuller, Gregory N; Zhang, Wei

    2011-04-01

    Allelic loss of the short arm of chromosome 1 has been observed frequently in a wide spectrum of cancers, most frequently in oligodendroglioma. In our previous studies, we evaluated 177 oligodendroglial tumor samples and identified the AJAP1 gene (formerly Shrew1) in the consensus region of deletion. AJAP1 is a transmembrane protein found in adheren junctions and functions to inhibit glioma cell adhesion and migration. Whereas a putative tumor suppressor gene, we did not detect AJAP1 gene mutations. In subsequent studies, we found that AJAP1 was underexpressed in oligodendrogliomas relative to normal brain tissues. Bioinformatic analysis revealed the presence of CpG islands in the promoter of AJAP1. Methylation analysis of the AJAP1 promoter identified hypermethylation in 21% of oligodendrogliomas (n =27), and the degree of methylation correlated with low levels of AJAP1 expression (P = 0.045). The AJAP1 promoter was also highly methylated in a wide spectrum of cell lines (n = 22), including cell lines of glioblastoma. Analysis of the National Cancer Institute's REMBRANDT dataset, which contains 343 glioma samples, indicated that low AJAP1 gene expression was associated with decreased survival. Thus, both genetic (gene deletion) and epigenetic alterations (promoter methylation) are likely mechanisms that inactivate the putative tumor suppressor AJAP1 in gliomas, which contributes to poor prognosis.

  17. Identification of myeloid derived suppressor cells in the peripheral blood of tumor bearing dogs

    OpenAIRE

    Sherger Matthew; Kisseberth William; London Cheryl; Olivo-Marston Susan; Papenfuss Tracey L

    2012-01-01

    Abstract Background Myeloid derived suppressor cells (MDSCs) are a recently described population of immune cells that significantly contribute to the immunosuppression seen in cancer patients. MDSCs are one of the most important factors that limit the efficacy of cancer immunotherapy (e.g. cancer vaccines) and MDSC levels are increased in cancer in multiple species. Identifying and targeting MDSCs is actively being investigated in the field of human oncology and is increasingly being investig...

  18. Regulation of a senescence checkpoint response by the E2F1 transcription factor and p14ARF tumor suppressor

    Energy Technology Data Exchange (ETDEWEB)

    Dimri, Goberdhan P.; Itahana, Koji; Acosta, Meileen; Campisi, Judith

    1999-11-05

    Normal cells do not divide indefinitely due to a process known as replicative senescence. Human cells arrest growth with a senescent phenotype when they acquire one or more critically short telomere as a consequence of cell division. Recent evidence suggests that certain types of DNA damage, chromatin remodeling, or oncogenic forms of Rasor Raf can also elicit a senescence response. We show here that E2F1, a multifunctional transcription factor that binds the retinoblastoma (pRb) tumor suppressor and can either promote or suppress tumorigenesis, induces a senescent phenotype when overexpressed in normal human fibroblasts. Normal human cells stably arrested proliferation and expressed several markers of replicative senescence in response to E2F1. This activity of E2F1 was independent of its pRb binding activity, but dependent on its ability to stimulate gene expression. The E2F1 target gene critical for the senescence response appeared to be the p14ARF tumor suppressor. Replicatively senescent human fibroblasts overexpressed p14ARF, and ectopic expression of p14ARF in presenescent cells induced a phenotype similar to that induced by E2F1. Consistent with a critical role for p14ARF, cells with compromised p53 function were immune to senescence induction by E2F1, as were cells deficient in p14ARF. Our findings support the idea that the senescence response is a critical tumor suppressive mechanism, provide an explanation for the apparently paradoxical roles of E2F1 in oncogenesis, and identify p14ARF as a potentially important mediator of the senescent phenotype.

  19. TRIM26 functions as a novel tumor suppressor of hepatocellular carcinoma and its downregulation contributes to worse prognosis

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yi, E-mail: wangyichenben@163.com [Department of General Surgery, The Affiliated Baoan Hospital of Southern Medical University, Shenzhen, Guangdong, 518101 (China); He, Du, E-mail: hdu1234@163.com [Department of Oncology, The Central Hospital of Enshi Autonomous of Prefecture, Enshi Clinical College of Wuhan University, Enshi, Hubei, 445000 (China); Yang, Liang, E-mail: yliang0689@163.com [Department of Oncology, Qianjiang Central Hospital, Qianjiang, Hubei, 433100 (China); Wen, Bo, E-mail: tjwb001@126.com [Department of Urology, The Affiliated Baoan Hospital of Southern Medical University, Shenzhen, Guangdong, 518101 (China); Dai, Jinfen, E-mail: brilliant_510@126.com [Department of Gastroenterology, Renmin Hospital of Wuhan University, Wuhan, Hubei, 430060 (China); Zhang, Qian, E-mail: anny9655@126.com [Department of Immunology, School of Basic Medicine, Wuhan University, Wuhan, Hubei, 430071 (China); Kang, Jian, E-mail: 984190619@qq.com [Department of Gastroenterology, Renmin Hospital of Wuhan University, Wuhan, Hubei, 430060 (China); He, Weiyang, E-mail: 996114664@qq.com [Department of Immunology, School of Basic Medicine, Wuhan University, Wuhan, Hubei, 430071 (China); Ding, Qianshan, E-mail: iamdqs@163.com [Department of Gastroenterology, Renmin Hospital of Wuhan University, Wuhan, Hubei, 430060 (China); He, De, E-mail: 18938027146@126.com [Department of General Surgery, The Affiliated Baoan Hospital of Southern Medical University, Shenzhen, Guangdong, 518101 (China)

    2015-07-31

    Hepatocellular carcinoma (HCC) is the one of the most common malignancies worldwide and its prognosis is extremely poor. Tripartite motif (TRIM) proteins play crucial roles in cancer cell biology but the function of tripartite motif 26 (TRIM26) has not been investigated. We demonstrated that low expression level of TRIM26 in tumor samples was significantly correlated with worse prognosis in HCC patients. We also demonstrated its expression level was associated with several clinicopathologic features such as AFP level and T stage of HCC patients. Furthermore, we validated that TRIM26 was significantly downregulated in HCC tissue compared with normal liver tissue. To further clarify the functional role of TRIM26 in HCC, We confirmed that TRIM26 silencing can promote cancer cell proliferation, colony forming, migration and invasion in vitro with HCC cell lines HepG2 and Bel-7402. Then we utilized bioinformatic tool to predict gene influenced by TRIM26, showing TRIM26 could modulate gene sets about cancer cell metabolism. In conclusion, we proved that TRIM26 is a novel tumor suppressor modulating multiple metabolism-related pathways in HCC. To our best knowledge, this is the first study to investigate the function of TRIM26 in cancer biology. Our findings provide useful insight into the mechanism of HCC origin and progression. Moreover, TRIM26 may represent a novel therapeutic target for HCC. - Highlights: • TRIM26 is down-regulated in liver cancer samples and functions as a novel tumor suppressor. • Down-regulation of TRIM26 is associated with worse prognosis of hepatocellular carcinoma (HCC). • Knockdown of TRIM26 promotes the proliferation and metastasis of HCC cells. • TRIM26 may function in abnormal metabolic progress of HCC.

  20. Human umbilical cord matrix mesenchymal stem cells suppress the growth of breast cancer by expression of tumor suppressor genes.

    Directory of Open Access Journals (Sweden)

    Naomi Ohta

    Full Text Available Human and rat umbilical cord matrix mesenchymal stem cells (UCMSC possess the ability to control the growth of breast carcinoma cells. Comparative analyses of two types of UCMSC suggest that rat UCMSC-dependent growth regulation is significantly stronger than that of human UCMSC. Their different tumoricidal abilities were clarified by analyzing gene expression profiles in the two types of UCMSC. Microarray analysis revealed differential gene expression between untreated naïve UCMSC and those co-cultured with species-matched breast carcinoma cells. The analyses screened 17 differentially expressed genes that are commonly detected in both human and rat UCMSC. The comparison between the two sets of gene expression profiles identified two tumor suppressor genes, adipose-differentiation related protein (ADRP and follistatin (FST, that were specifically up-regulated in rat UCMSC, but down-regulated in human UCMSC when they were co-cultured with the corresponding species' breast carcinoma cells. Over-expression of FST, but not ADRP, in human UCMSC enhanced their ability to suppress the growth of MDA-231 cells. The growth of MDA-231 cells was also significantly lower when they were cultured in medium conditioned with FST, but not ADRP over-expressing human UCMSC. In the breast carcinoma lung metastasis model generated with MDA-231 cells, systemic treatment with FST-over-expressing human UCMSC significantly attenuated the tumor burden. These results suggest that FST may play an important role in exhibiting stronger tumoricidal ability in rat UCMSC than human UCMSC and also implies that human UCMSC can be transformed into stronger tumoricidal cells by enhancing tumor suppressor gene expression.

  1. PCB153, TCDD and estradiol compromise the benzo[a]pyrene-induced p53-response via FoxO3a.

    Science.gov (United States)

    Al-Anati, Lauy; Kadekar, Sandeep; Högberg, Johan; Stenius, Ulla

    2014-08-05

    TCDD, polychlorinated biphenyls (PCB) and polycyclic aromatic hydrocarbons (PAH) coexist in the environment. However, there are few studies on combined effects of these compounds. We have studied the effect of TCDD, PCB153 and estradiol on p53 signaling induced by PAHs. We show that all three compounds amplified the accumulation of nuclear p53, elicited by benzo[a]pyrene (BaP) or dibenzo[al]pyrene (DBP). This effect was associated with an attenuated PAH-induced apoptosis and with decreased levels of phosphorylated FoxO3a Thr32. Thr32 phosphorylation of FoxO3a may promote a translocation of FoxO3a-p53 complex from nucleus to the cytoplasm, and the role of FoxO3a dephosphorylation was further studied. We found that inhibition of PP2A phosphatase restored levels of phosphorylated FoxO3a, led to cytosolic translocation of p53, and activated BaP-induced p53-mediated apoptosis. These results were confirmed by silencing FoxO3a with siRNA or by inhibiting 14-3-3 protein; also these treatments trapped BaP-induced p53 in the nucleus. Our data indicate interplay between p53, FoxO3a and 14-3-3 leading to an attenuated BaP induced apoptosis in cells co-exposed to TCDD, PCB 153 or estradiol.

  2. The forkhead transcription factor FOXO3a controls microglial inflammatory activation and eventual apoptotic injury through caspase 3.

    Science.gov (United States)

    Shang, Yan Chen; Chong, Zhao Zhong; Hou, Jinling; Maiese, Kenneth

    2009-02-01

    Memory loss and cognitive failure are increasingly being identified as potential risks with the recognized increase in life expectancy of the general population. As a result, the development of novel therapeutic strategies for disorders such as Alzheimer's disease have garnered increased attention. The etiologies that can lead to Alzheimer's disease are extremely varied, but a number of therapeutic options are directed against amyloid-beta peptide and inflammatory cell regulation to prevent or halt progressive cognitive loss. In particular, inflammatory microglial cells may have disparate functions that in some scenarios lead to disability through the removal of functional neurovascular cells and in other circumstances foster tissue repair. Given the significance microglial cells hold for neurodegenerative disorders, we therefore examined the function that amyloid (Abeta(1-42)) has upon the microglial cell line EOC 2 and identified a novel role for the forkhead transcription factor FoxO3a and caspase 3. Here we show that Abeta(1-42) leads to progressive injury and apoptotic cell loss in microglial cells that involves both early phosphatidylserine (PS) externalization and late genomic DNA fragmentation over a 24 hour course. Prior to these injury programs, Abeta(1-42) results in the activation and proliferation of microglia as demonstrated by increased proliferating cell nuclear antigen (PCNA) expression and bromodeoxyuridine (BrdU) uptake. Both apoptotic injury as well as the prior activation and proliferation of microglial cells relies upon the presence of FoxO3a, since specific gene silencing of FoxO3a promotes microglial cell protection and prevents the early activation and proliferation of these cells. Furthermore, Abeta(1-42) exposure maintained FoxO3a in an unphosphorylated "active" state and facilitated the cellular trafficking of FoxO3a from the cytoplasm to the cell nucleus to potentially lead to "pro-apoptotic" programs by this transcription factor. One apoptotic program in particular appears to involve the activation of caspase 3, since loss of FoxO3a through gene silencing prevents the induction of caspase 3 activity by Abeta(1-42).

  3. Enzymological analysis of the tumor suppressor A-C1 reveals a novel group of phospholipid-metabolizing enzymes.

    Science.gov (United States)

    Shinohara, Naoki; Uyama, Toru; Jin, Xing-Hua; Tsuboi, Kazuhito; Tonai, Takeharu; Houchi, Hitoshi; Ueda, Natsuo

    2011-11-01

    A-C1 protein is the product of a tumor suppressor gene negatively regulating the oncogene Ras and belongs to the HRASLS (HRAS-like suppressor) subfamily. We recently found that four members of this subfamily expressed in human tissues function as phospholipid-metabolizing enzymes. Here we examined a possible enzyme activity of A-C1. The homogenates of COS-7 cells overexpressing recombinant A-C1s from human, mouse, and rat showed a phospholipase A½ (PLA½) activity toward phosphatidylcholine (PC). This finding was confirmed with the purified A-C1. The activity was Ca²⁺ independent, and dithiothreitol and Nonidet P-40 were indispensable for full activity. Phosphatidylethanolamine (PE) was also a substrate and the phospholipase A₁ (PLA₁) activity was dominant over the PLA₂ activity. Furthermore, the protein exhibited acyltransferase activities transferring an acyl group of PCs to the amino group of PEs and the hydroxyl group of lyso PCs. As for tissue distribution in human, mouse, and rat, A-C1 mRNA was abundantly expressed in testis, skeletal muscle, brain, and heart. These results demonstrate that A-C1 is a novel phospholipid-metabolizing enzyme. Moreover, the fact that all five members of the HRASLS subfamily, including A-C1, show similar catalytic properties strongly suggests that these proteins constitute a new class of enzymes showing PLA½ and acyltransferase activities.

  4. The growth and tumor suppressors NORE1A and RASSF1A are targets for calpain-mediated proteolysis.

    Directory of Open Access Journals (Sweden)

    Sergey Kuznetsov

    Full Text Available BACKGROUND: NORE1A and RASSF1A are growth and tumour suppressors inactivated in a variety of cancers. Methylation of NORE1A and RASSF1A promoters is the predominant mechanism for downregulation of these proteins; however, other mechanisms are likely to exist. METHODOLOGY/PRINCIPAL FINDINGS: Here we describe a proteolysis of NORE1A and RASSF1A by calpains as alternative mechanism of their downregulation. Extracts of H358 cell line, a human bronchoalveolar carcinoma, and H460, a large cell carcinoma, were capable of proteolysis of NORE1A protein in the calpain-dependent manner. Likewise, RASSF1A tumor suppressor was proteolyzed by the H358 cell extract. Addition of calpain inhibitor to H358 and H460 cells growing in tissue culture resulted in re-expression of endogenous NORE1A. A survey of 10 human lung tumours revealed that three of them contain an activity capable of inducing NORE1A degradation. CONCLUSIONS/SIGNIFICANCE: Thus, degradation by calpains is a novel mechanism for downregulation of NORE1A and RASSF1A proteins and might be the mechanism allowing cancer cells to escape growth suppression.

  5. Tumor suppressor PRSS8 targets Sphk1/S1P/Stat3/Akt signaling in colorectal cancer

    Science.gov (United States)

    Wang, Qian; Li, Zexin; Yang, Yiqiong; Chen, Zhiguo; Wang, Jianguo; Zhao, Weixing; Zhang, Huijuan; Chen, Jiwang; Dong, Huali; Shen, Kui; Diamond, Alan M.; Yang, Wancai

    2016-01-01

    PRSS8 is a membrane-anchored serine protease prostasin and has been shown an association with carcinogenesis. Herein we found that PRSS8 expression was significantly reduced in colorectal adenomas and adenocarcinomas. The decreased PRSS8 was well correlated with clinical stages, poor differentiation and shorter survival time of colorectal cancer. Furthermore, increase of PRSS8 led to the inhibition of colorectal cancer cell proliferation, knockdown of PRSS8 accelerated cell proliferation in vitro, and overexpressing PRSS8 retarded cancer cell growth in nude mice. Mechanistic studies revealed that PRSS8 inhibited Sphk1/S1P/Stat3/Akt signaling pathway, in terms of inverse association between PRSS8 and Sphk1 in human colorectal cancers and in Sphk1-/− mice. In conclusion, PRSS8 acts as a tumor suppressor by inhibiting Sphk1/S1P/Stat3/Akt signaling pathway, and could be used as a biomarker to monitor colorectal carcinogenesis and predict outcomes. PMID:27050145

  6. [Current status of p53 tumor suppressor gene as a possible molecular marker of cancer of the prostate].

    Science.gov (United States)

    Peña González, J A; Morote Robles, J; de Torres Ramírez, I M; Martínez Cuenca, E

    1998-04-01

    Diagnosis of prostate cancer has increased over the last few years both in localized and in more advanced stages. At present, several groups are working in the search and evaluation of alternative tumoral markers as the current ones do not cover all the Urologist's needs. In this context, a number of studies on the mutation of the tumour suppressor gen p53 in both localized and metastatic prostate cancer are being carried out. When a noxa acts on the DNA, protein p53 inhibits the cell cycle allowing the repair systems to operate and, if the damage is significant enough, cell apoptosis. The loss of this control mechanism secondary to the synthesis of anomalous proteins can result in the proliferation of neoplastic cells. A revision of the most representative papers in the literature is presented here, addressing the surrounding controversy and the resulting future possibilities.

  7. Expression patterns of the tumor suppressor PDCD4 and correlation with β-catenin expression in gastric cancers.

    Science.gov (United States)

    Kakimoto, Takashi; Shiraishi, Ryosuke; Iwakiri, Ryuichi; Fujimoto, Kazuma; Takahashi, Hirokazu; Hamajima, Hiroshi; Mizuta, Toshihiko; Ideguchi, Hiroyuki; Toda, Shuji; Kitajima, Yoshihiko; Ozaki, Iwata; Matsuhashi, Sachiko

    2011-12-01

    The expression patterns of PDCD4, a tumor suppressor, and β-catenin were immunohistologically investigated in gastric carcinoma tissues. In normal gastric tissues, PDCD4 was strongly expressed in the cell nuclei, but weakly expressed in the cytoplasm. In gastric adenocarcinoma tissues, nuclear PDCD4 expression was decreased, while cytoplasmic PDCD4 expression was unchanged or somewhat increased. In gastric signet ring cell carcinoma tissues, PDCD4 expression patterns were different from the expression patterns of the adenocarcinoma tissues, and PDCD4 was localized in the nuclei of the carcinoma cells as a belt in the middle of the epithelial layer. The nuclear localization of PDCD4 in the adenocarcinoma tissues was correlated with the membrane localization of β-catenin, the activation of which stimulates invasion of colon cancer cells. PDCD4 expression was correlated with β-catenin expression in gastric carcinoma cell lines, but not with E-cadherin, as the binding partner in the cell membrane.

  8. ING Genes Work as Tumor Suppressor Genes in the Carcinogenesis of Head and Neck Squamous Cell Carcinoma.

    Science.gov (United States)

    Li, Xiaohan; Kikuchi, Keiji; Takano, Yasuo

    2011-01-01

    Head and neck squamous cell carcinoma (HNSCC) is the sixth most common cancer in the world. The evolution and progression of HNSCC are considered to result from multiple stepwise alterations of cellular and molecular pathways in squamous epithelium. Recently, inhibitor of growth gene (ING) family consisting of five genes, ING1 to ING5, was identified as a new tumor suppressor gene family that was implicated in the downregulation of cell cycle and chromatin remodeling. In contrast, it has been shown that ING1 and ING2 play an oncogenic role in some cancers, this situation being similar to TGF-β. In HNSCC, the ING family has been reported to be downregulated, and ING translocation from the nucleus to the cytoplasm may be a critical event for carcinogenesis. In this paper, we describe our recent results and briefly summarize current knowledge regarding the biologic functions of ING in HNSCC.

  9. A Pathologic Link between Wilms Tumor Suppressor Gene, WT1, and IFI16

    Directory of Open Access Journals (Sweden)

    Marianne K-H. Kim

    2008-01-01

    Full Text Available The Wilms tumor gene (WT1 is mutated or deleted in patients with heredofamilial syndromes associated with the development of Wilms tumors, but is infrequently mutated in sporadic Wilms tumors. By comparing the microarray profiles of syndromic versus sporadic Wilms tumors and WT1-inducible Saos-2 osteosarcoma cells, we identified interferon-inducible protein 16 (IFI16, a transcriptional modulator, as a differentially expressed gene and a candidate WT1 target gene. WT1 induction in Saos-2 osteosarcoma cells led to strong induction of IFI16 expression and its promoter activity was responsive to the WT1 protein. Immunohistochemical analysis showed that IFI16 and WT1 colocalized in WT1-replete Wilms tumors, but not in normal human midgestation fetal kidneys, suggesting that the ability of WT1 to regulate IFI16 in tumors represented an aberrant pathologic relationship. In addition, endogenous IFI16 and WT1 interacted in vivo in two Wilms tumor cell lines. Furthermore, IFI16 augmented the transcriptional activity of WT1 on both synthetic and physiological promoters. Strikingly, short hairpin RNA (shRNA-mediated knockdown of either IFI16 or WT1 led to decreased growth of Wilms tumor cells. These data suggest that IFI16 and WT1, in certain cellular context including sporadic Wilms tumors, may support cell survival.

  10. The Role of Tumor Suppressor Gene TIP30 in tumorigenesis and metastasis

    Institute of Scientific and Technical Information of China (English)

    Jian ZHAO; Yajun GUO

    2009-01-01

    @@ Background: Malignant tumors are characterized by dysregulated growth control, the overcoming of replicative senescence, evasion of apoptnsis, tis-sue invasion and metastasis, and sustained angiogenesis.

  11. Effects of sulfur dioxide derivatives on expression of oncogenes and tumor suppressor genes in human bronchial epithelial cells.

    Science.gov (United States)

    Qin, Guohua; Meng, Ziqiang

    2009-04-01

    Sulfur dioxide (SO(2)) is a major air pollutant suspected to act as a promoter or co-carcinogen. The present study was designed to investigate whether SO(2) derivatives (bisulfite and sulfite) had effects on the expression of several proto-oncogenes and tumor suppressor genes in cultured human bronchial epithelial (BEP2D) cells. The mRNA and protein levels were measured by real-time RT-PCR and western blotting, respectively, following exposure to differing SO(2)-derivative concentrations and exposure times. SO(2) derivatives caused mRNA and protein over-expression of c-fos, c-jun, and c-myc at all tested doses (0.001-2mM). Over-expression of H-ras and p53 were observed in cells receiving the highest concentration (0.1-2mM), as well as the under-expression of p16 and Rb. The over-expression of c-fos and c-jun was observed after 24h recovery. The expression of c-myc and H-ras decreased to base line levels while the p53 expression decreased compared with control after 24h recovery. The mRNA and protein expression of p16 and Rb remained at initial levels after 24h recovery. The data support the hypothesis that SO(2) derivatives could cause the activation of proto-oncogenes and inactivation of tumor suppressor genes and SO(2) derivatives may play a role in the pathogenesis of SO(2)-associated lung cancer.

  12. Senescence-Associated Secretory Phenotypes Reveal Cell-Nonautonomous Functions of Oncogenic RAS and the p53 Tumor Suppressor

    Energy Technology Data Exchange (ETDEWEB)

    Copp& #233; , Jean-Philippe; Patil, Christopher; Rodier, Francis; Sun, Yu; Munoz, Denise; Goldstein, Joshua; Nelson, Peter; Desprez, Pierre-Yves; Campisi, Judith

    2008-10-24

    Cellular senescence suppresses cancer by arresting cell proliferation, essentially permanently, in response to oncogenic stimuli, including genotoxic stress. We modified the use of antibody arrays to provide a quantitative assessment of factors secreted by senescent cells. We show that human cells induced to senesce by genotoxic stress secrete myriad factors associated with inflammation and malignancy. This senescence-associated secretory phenotype (SASP) developed slowly over several days and only after DNA damage of sufficient magnitude to induce senescence. Remarkably similar SASPs developed in normal fibroblasts, normal epithelial cells, and epithelial tumor cells after genotoxic stress in culture, and in epithelial tumor cells in vivo after treatment of prostate cancer patients with DNA-damaging chemotherapy. In cultured premalignant epithelial cells, SASPs induced an epithelial-mesenchyme transition and invasiveness, hallmarks of malignancy, by a paracrine mechanism that depended largely on the SASP factors interleukin (IL)-6 and IL-8. Strikingly, two manipulations markedly amplified, and accelerated development of, the SASPs: oncogenic RAS expression, which causes genotoxic stress and senescence in normal cells, and functional loss of the p53 tumor suppressor protein. Both loss of p53 and gain of oncogenic RAS also exacerbated the promalignant paracrine activities of the SASPs. Our findings define a central feature of genotoxic stress-induced senescence. Moreover, they suggest a cell-nonautonomous mechanism by which p53 can restrain, and oncogenic RAS can promote, the development of age-related cancer by altering the tissue microenvironment.

  13. Absence of mutations in the coding sequence of the potential tumor suppressor 3pK in metastatic melanoma

    Directory of Open Access Journals (Sweden)

    Houben Roland

    2005-12-01

    Full Text Available Abstract Background Activation of Ras or Raf contributes to tumorigenesis of melanoma. However, constitutive Raf activation is also a characteristic of the majority of benign melanocytic nevi and high intensity signaling of either Ras or Raf was found to induce growth inhibition and senescence rather than transformation. Since the chromosome 3p kinase (3pK is a target of the Ras/Raf/Mek/Erk signaling pathway which antagonizes the function of the oncogene and anti-differentiation factor Bmi-1, 3pK may function as a tumor suppressor in tumors with constitutive Ras/Raf activation. Consequently, we tested whether inactivating 3pK mutations are present in melanoma. Methods 30 metastatic melanoma samples, which were positive for activating mutations of either BRaf or NRas, were analyzed for possible mutations in the 3pk gene. The 10 coding exons and their flanking intron sequences were amplified by PCR and direct sequencing of the PCR products was performed. Results This analysis revealed that besides the presence of some single nucleotide polymorphisms in the 3pk gene, we could not detect any possible loss of function mutation in any of these 30 metastatic melanoma samples selected for the presence of activating mutations within the Ras/Raf/Mek/Erk signaling pathway. Conclusion Hence, in melanoma with constitutively active Ras/Raf inactivating mutations within the 3pk gene do not contribute to the oncogenic phenotype of this highly malignant tumor.

  14. Multiple Components of the VHL Tumor Suppressor Complex Are Frequently Affected by DNA Copy Number Loss in Pheochromocytoma

    Science.gov (United States)

    Rowbotham, David A.; Enfield, Katey S. S.; Martinez, Victor D.; Thu, Kelsie L.; Vucic, Emily A.; Stewart, Greg L.; Bennewith, Kevin L.; Lam, Wan L.

    2014-01-01

    Pheochromocytomas (PCC) are rare tumors that arise in chromaffin tissue of the adrenal gland. PCC are frequently inherited through predisposing mutations in genes such as the von Hippel-Lindau (VHL) tumor suppressor. VHL is part of the VHL elongin BC protein complex that also includes CUL2/5, TCEB1, TCEB2, and RBX1; in normoxic conditions this complex targets hypoxia-inducible factor 1 alpha (HIF1A) for degradation, thus preventing a hypoxic response. VHL inactivation by genetic mechanisms, such as mutation and loss of heterozygosity, inhibits HIF1A degradation, even in the presence of oxygen, and induces a pseudohypoxic response. However, the described <10% VHL mutation rate cannot account for the high frequency of hypoxic response observed. Indeed, little is known about genetic mechanisms disrupting other complex component genes. Here, we show that, in a panel of 171 PCC tumors, 59.6% harbored gene copy number loss (CNL) of at least one complex component. CNL significantly reduced gene expression and was associated with enrichment of gene targets controlled by HIF1. Interestingly, we show that VHL-related renal clear cell carcinoma harbored disruption of VHL alone. Our results indicate that VHL elongin BC protein complex components other than VHL could be important for PCC tumorigenesis and merit further investigation. PMID:25298778

  15. Multiple Components of the VHL Tumor Suppressor Complex Are Frequently Affected by DNA Copy Number Loss in Pheochromocytoma

    Directory of Open Access Journals (Sweden)

    David A. Rowbotham

    2014-01-01

    Full Text Available Pheochromocytomas (PCC are rare tumors that arise in chromaffin tissue of the adrenal gland. PCC are frequently inherited through predisposing mutations in genes such as the von Hippel-Lindau (VHL tumor suppressor. VHL is part of the VHL elongin BC protein complex that also includes CUL2/5, TCEB1, TCEB2, and RBX1; in normoxic conditions this complex targets hypoxia-inducible factor 1 alpha (HIF1A for degradation, thus preventing a hypoxic response. VHL inactivation by genetic mechanisms, such as mutation and loss of heterozygosity, inhibits HIF1A degradation, even in the presence of oxygen, and induces a pseudohypoxic response. However, the described <10% VHL mutation rate cannot account for the high frequency of hypoxic response observed. Indeed, little is known about genetic mechanisms disrupting other complex component genes. Here, we show that, in a panel of 171 PCC tumors, 59.6% harbored gene copy number loss (CNL of at least one complex component. CNL significantly reduced gene expression and was associated with enrichment of gene targets controlled by HIF1. Interestingly, we show that VHL-related renal clear cell carcinoma harbored disruption of VHL alone. Our results indicate that VHL elongin BC protein complex components other than VHL could be important for PCC tumorigenesis and merit further investigation.

  16. Multiple Components of the VHL Tumor Suppressor Complex Are Frequently Affected by DNA Copy Number Loss in Pheochromocytoma.

    Science.gov (United States)

    Rowbotham, David A; Enfield, Katey S S; Martinez, Victor D; Thu, Kelsie L; Vucic, Emily A; Stewart, Greg L; Bennewith, Kevin L; Lam, Wan L

    2014-01-01

    Pheochromocytomas (PCC) are rare tumors that arise in chromaffin tissue of the adrenal gland. PCC are frequently inherited through predisposing mutations in genes such as the von Hippel-Lindau (VHL) tumor suppressor. VHL is part of the VHL elongin BC protein complex that also includes CUL2/5, TCEB1, TCEB2, and RBX1; in normoxic conditions this complex targets hypoxia-inducible factor 1 alpha (HIF1A) for degradation, thus preventing a hypoxic response. VHL inactivation by genetic mechanisms, such as mutation and loss of heterozygosity, inhibits HIF1A degradation, even in the presence of oxygen, and induces a pseudohypoxic response. However, the described complex component genes. Here, we show that, in a panel of 171 PCC tumors, 59.6% harbored gene copy number loss (CNL) of at least one complex component. CNL significantly reduced gene expression and was associated with enrichment of gene targets controlled by HIF1. Interestingly, we show that VHL-related renal clear cell carcinoma harbored disruption of VHL alone. Our results indicate that VHL elongin BC protein complex components other than VHL could be important for PCC tumorigenesis and merit further investigation.

  17. C-Myc negatively controls the tumor suppressor PTEN by upregulating miR-26a in glioblastoma multiforme cells

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Pin; Nie, Quanmin; Lan, Jin; Ge, Jianwei [Department of Neurosurgery, Ren Ji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200127 (China); Qiu, Yongming, E-mail: qiuzhoub@hotmail.com [Department of Neurosurgery, Ren Ji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200127 (China); Shanghai Institute of Head Trauma, Shanghai 200127 (China); Mao, Qing, E-mail: maoq@netease.com [Department of Neurosurgery, Ren Ji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200127 (China); Shanghai Institute of Head Trauma, Shanghai 200127 (China)

    2013-11-08

    Highlights: •The c-Myc oncogene directly upregulates miR-26a expression in GBM cells. •ChIP assays demonstrate that c-Myc interacts with the miR-26a promoter. •Luciferase reporter assays show that PTEN is a specific target of miR-26a. •C-Myc–miR-26a suppression of PTEN may regulate the PTEN/AKT pathway. •Overexpression of c-Myc enhances the proliferative capacity of GBM cells. -- Abstract: The c-Myc oncogene is amplified in many tumor types. It is an important regulator of cell proliferation and has been linked to altered miRNA expression, suggesting that c-Myc-regulated miRNAs might contribute to tumor progression. Although miR-26a has been reported to be upregulated in glioblastoma multiforme (GBM), the mechanism has not been established. We have shown that ectopic expression of miR-26a influenced cell proliferation by targeting PTEN, a tumor suppressor gene that is inactivated in many common malignancies, including GBM. Our findings suggest that c-Myc modulates genes associated with oncogenesis in GBM through deregulation of miRNAs via the c-Myc–miR-26a–PTEN signaling pathway. This may be of clinical relevance.

  18. Senescence-associated secretory phenotypes reveal cell-nonautonomous functions of oncogenic RAS and the p53 tumor suppressor.

    Directory of Open Access Journals (Sweden)

    Jean-Philippe Coppé

    2008-12-01

    Full Text Available Cellular senescence suppresses cancer by arresting cell proliferation, essentially permanently, in response to oncogenic stimuli, including genotoxic stress. We modified the use of antibody arrays to provide a quantitative assessment of factors secreted by senescent cells. We show that human cells induced to senesce by genotoxic stress secrete myriad factors associated with inflammation and malignancy. This senescence-associated secretory phenotype (SASP developed slowly over several days and only after DNA damage of sufficient magnitude to induce senescence. Remarkably similar SASPs developed in normal fibroblasts, normal epithelial cells, and epithelial tumor cells after genotoxic stress in culture, and in epithelial tumor cells in vivo after treatment of prostate cancer patients with DNA-damaging chemotherapy. In cultured premalignant epithelial cells, SASPs induced an epithelial-mesenchyme transition and invasiveness, hallmarks of malignancy, by a paracrine mechanism that depended largely on the SASP factors interleukin (IL-6 and IL-8. Strikingly, two manipulations markedly amplified, and accelerated development of, the SASPs: oncogenic RAS expression, which causes genotoxic stress and senescence in normal cells, and functional loss of the p53 tumor suppressor protein. Both loss of p53 and gain of oncogenic RAS also exacerbated the promalignant paracrine activities of the SASPs. Our findings define a central feature of genotoxic stress-induced senescence. Moreover, they suggest a cell-nonautonomous mechanism by which p53 can restrain, and oncogenic RAS can promote, the development of age-related cancer by altering the tissue microenvironment.

  19. Analysis of a new homozygous deletion in the tumor suppressor region at 3p12.3 reveals two novel intronic noncoding RNA genes

    NARCIS (Netherlands)

    Angeloni, Debora; ter Elst, Arja; Wei, Ming Hui; van der Veen, Anneke Y.; Braga, Eleonora A.; Klimov, Eugene A.; Timmer, Tineke; Korobeinikova, Luba; Lerman, Michael I.; Buys, Charles H. C. M.

    2006-01-01

    Homozygous deletions or loss of heterozygosity (LOH) at human chromosome band 3p12 are consistent features of lung and other malignancies, suggesting the presence of a tumor suppressor gene(s) (TSG) at this location. Only one gene has been cloned thus far from the overlapping region deleted in lung

  20. Multi-gene epigenetic silencing of tumor suppressor genes in T-cell lymphoma cells; delayed expression of the p16 protein upon reversal of the silencing

    DEFF Research Database (Denmark)

    Nagasawa, T; Zhang, Q; Raghunath, P N

    2006-01-01

    To understand better T-cell lymphomagenesis, we examined promoter CpG methylation and mRNA expression of closely related genes encoding p16, p15, and p14 tumor suppressor genes in cultured malignant T-cells that were derived from cutaneous, adult type, and anaplastic lymphoma kinase (ALK)-express...

  1. Identification of Tumor Suppressors and Oncogenes from Genomic and Epigenetic Features in Ovarian Cancer

    NARCIS (Netherlands)

    Wrzeszczynski, K.O.; Varadan, V.; Byrnes, J.; Lum, E.; Kamalakaran, S.; Levine, D.A.; Dimitrova, N.; Zhang, M.Q.; Lucito, R.

    2011-01-01

    The identification of genetic and epigenetic alterations from primary tumor cells has become a common method to identify genes criticalto the development and progression of cancer. We seek to identify those genetic and epigenetic aberrations that have the most impact ongene function within the tumor

  2. Mourning Dr. Alfred G. Knudson: the two-hit hypothesis, tumor suppressor genes, and the tuberous sclerosis complex.

    Science.gov (United States)

    Hino, Okio; Kobayashi, Toshiyuki

    2017-01-01

    On July 10, 2016, Alfred G. Knudson, Jr., MD, PhD, a leader in cancer research, died at the age of 93 years. We deeply mourn his loss. Knudson's two-hit hypothesis, published in 1971, has been fundamental for understanding tumor suppressor genes and familial tumor-predisposing syndromes. To understand the molecular mechanism of two-hit-initiated tumorigenesis, Knudson used an animal model of a dominantly inherited tumor, the Eker rat. From the molecular identification of Tsc2 germline mutations, the Eker rat became a model for tuberous sclerosis complex (TSC), a familial tumor-predisposing syndrome. Animal models, including the fly, have greatly contributed to TSC research. Because the product of the TSC2/Tsc2 gene (tuberin) together with hamartin, the product of another TSC gene (TSC1/Tsc1), suppresses mammalian/mechanistic target of rapamycin complex 1 (mTORC1), rapalogs have been used as therapeutic drugs for TSC. Although significant activity of these drugs has been reported, there are still problems such as recurrence of residual tumors and adverse effects. Recent studies indicate that there are mTORC1-independent signaling pathways downstream of hamartin/tuberin, which may represent new therapeutic targets. The establishment of cellular models, such as pluripotent stem cells with TSC2/Tsc2 gene mutations, will facilitate the understanding of new aspects of TSC pathogenesis and the development of novel treatment options. In this review, we look back at the history of Knudson and animal models of TSC and introduce recent progress in TSC research.

  3. Overexpression of FOXO3, MYD88, and GAPDH Identified by Suppression Subtractive Hybridization in Esophageal Cancer Is Associated with Autophagy.

    Science.gov (United States)

    Soltany-Rezaee-Rad, Mohammad; Mottaghi-Dastjerdi, Negar; Setayesh, Neda; Roshandel, Gholamreza; Ebrahimifard, Farzaneh; Sepehrizadeh, Zargham

    2014-01-01

    To find genes involved in tumorigenesis and the development of esophageal cancer, the suppression subtractive hybridization (SSH) method was used to identify genes that are overexpressed in esophageal cancer tissues compared to normal esophageal tissues. In our SSH library, the forkhead box O3 (FOXO3), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), and myeloid differentiation primary response 88 (MYD88) genes were the most highly upregulated genes, and they were selected for further studies because of their potential role in the induction of autophagy. Upregulation of these genes was also observed in clinical samples using qRT-PCR. In addition, coexpression analysis of the autophagy-related genes Beclin1, ATG12, Gabarapl, PIK3C3, and LC3 demonstrated a significant correlation between the differentially overexpressed genes and autophagy. Autophagy is an important mechanism in tumorigenesis and the development of chemoresistance in cancer cells. The upregulation of FOXO3, GAPDH, and MYD88 variants in esophageal cancer suggests a role for autophagy and provides new insight into the biology of esophageal cancer. We propose that FOXO3, GAPDH, and MYD88 are novel targets for combating autophagy in esophageal cancer.

  4. Overexpression of FOXO3, MYD88, and GAPDH Identified by Suppression Subtractive Hybridization in Esophageal Cancer Is Associated with Autophagy

    Directory of Open Access Journals (Sweden)

    Mohammad Soltany-Rezaee-Rad

    2014-01-01

    Full Text Available To find genes involved in tumorigenesis and the development of esophageal cancer, the suppression subtractive hybridization (SSH method was used to identify genes that are overexpressed in esophageal cancer tissues compared to normal esophageal tissues. In our SSH library, the forkhead box O3 (FOXO3, glyceraldehyde-3-phosphate dehydrogenase (GAPDH, and myeloid differentiation primary response 88 (MYD88 genes were the most highly upregulated genes, and they were selected for further studies because of their potential role in the induction of autophagy. Upregulation of these genes was also observed in clinical samples using qRT-PCR. In addition, coexpression analysis of the autophagy-related genes Beclin1, ATG12, Gabarapl, PIK3C3, and LC3 demonstrated a significant correlation between the differentially overexpressed genes and autophagy. Autophagy is an important mechanism in tumorigenesis and the development of chemoresistance in cancer cells. The upregulation of FOXO3, GAPDH, and MYD88 variants in esophageal cancer suggests a role for autophagy and provides new insight into the biology of esophageal cancer. We propose that FOXO3, GAPDH, and MYD88 are novel targets for combating autophagy in esophageal cancer.

  5. FOXO3A regulation by miRNA-29a Controls chondrogenic differentiation of mesenchymal stem cells and cartilage formation.

    Science.gov (United States)

    Guérit, David; Brondello, Jean-Marc; Chuchana, Paul; Philipot, Didier; Toupet, Karine; Bony, Claire; Jorgensen, Christian; Noël, Danièle

    2014-06-01

    Skeletal development and cartilage formation require stringent regulation of gene expression for mesenchymal stem cells (MSCs) to progress through stages of differentiation. Since microRNAs (miRNAs) regulate biological processes, the objective of the present study was to identify novel miRNAs involved in the modulation of chondrogenesis. We performed miRNA profiling and identify miR-29a as being one of the most down-regulated miRNAs during the chondrogenesis. Using chromatin immunoprecipitation, we showed that SOX9 down-regulates its transcription. Moreover, the over-expression of miR-29a strongly inhibited the expression of chondrocyte-specific markers during in vitro chondrogenic differentiation of MSCs. We identified FOXO3A as a direct target of miR-29a and showed a down- and up-regulation of FOXO3a protein levels after transfection of, respectively, premiR- and antagomiR-29a oligonucleotides. Finally, we showed that using the siRNA or premiR approach, chondrogenic differentiation was inhibited to a similar extent. Together, we demonstrate that the down-regulation of miR-29a, concomitantly with FOXO3A up-regulation, is essential for the differentiation of MSCs into chondrocytes and in vivo cartilage/bone formation. The delivery of miRNAs that modulate MSC chondrogenesis may be applicable for cartilage regeneration and deserves further investigation.

  6. Role of PINCH and its partner tumor suppressor Rsu-1 in regulating liver size and tumorigenesis.

    Directory of Open Access Journals (Sweden)

    Shashikiran Donthamsetty

    Full Text Available Particularly interesting new cysteine-histidine-rich protein (PINCH protein is part of the ternary complex known as the IPP (integrin linked kinase (ILK-PINCH-Parvin-α complex. PINCH itself binds to ILK and to another protein known as Rsu-1 (Ras suppressor 1. We generated PINCH 1 and PINCH 2 Double knockout mice (referred as PINCH DKO mice. PINCH2 elimination was systemic whereas PINCH1 elimination was targeted to hepatocytes. The genetically modified mice were born normal. The mice were sacrificed at different ages after birth. Soon after birth, they developed abnormal hepatic histology characterized by disorderly hepatic plates, increased proliferation of hepatocytes and biliary cells and increased deposition of extracellular matrix. After a sustained and prolonged proliferation of all epithelial components, proliferation subsided and final liver weight by the end of 30 weeks in livers with PINCH DKO deficient hepatocytes was 40% larger than the control mice. The livers of the PINCH DKO mice were also very stiff due to increased ECM deposition throughout the liver, with no observed nodularity. Mice developed liver cancer by one year. These mice regenerated normally when subjected to 70% partial hepatectomy and did not show any termination defect. Ras suppressor 1 (Rsu-1 protein, the binding partner of PINCH is frequently deleted in human liver cancers. Rsu-1 expression is dramatically decreased in PINCH DKO mouse livers. Increased expression of Rsu-1 suppressed cell proliferation and migration in HCC cell lines. These changes were brought about not by affecting activation of Ras (as its name suggests but by suppression of Ras downstream signaling via RhoGTPase proteins. In conclusion, our studies suggest that removal of PINCH results in enlargement of liver and tumorigenesis. Decreased levels of Rsu-1, a partner for PINCH and a protein often deleted in human liver cancer, may play an important role in the development of the observed phenotype.

  7. The Innate Immune Receptor NLRX1 Functions as a Tumor Suppressor by Reducing Colon Tumorigenesis and Key Tumor-Promoting Signals

    Directory of Open Access Journals (Sweden)

    A. Alicia Koblansky

    2016-03-01

    Full Text Available NOD-like receptor (NLR proteins are intracellular innate immune sensors/receptors that regulate immunity. This work shows that NLRX1 serves as a tumor suppressor in colitis-associated cancer (CAC and sporadic colon cancer by keeping key tumor promoting pathways in check. Nlrx1−/− mice were highly susceptible to CAC, showing increases in key cancer-promoting pathways including nuclear factor κB (NF-κB, mitogen-activated protein kinase (MAPK, signal transducer and activator of transcription 3 (STAT3, and interleukin 6 (IL-6. The tumor-suppressive function of NLRX1 originated primarily from the non-hematopoietic compartment. This prompted an analysis of NLRX1 function in the Apcmin/+ genetic model of sporadic gastrointestinal cancer. NLRX1 attenuated Apcmin/+ colon tumorigenesis, cellular proliferation, NF-κB, MAPK, STAT3 activation, and IL-6 levels. Application of anti-interleukin 6 receptor (IL6R antibody therapy reduced tumor burden, increased survival, and reduced STAT3 activation in Nlrx1−/−Apcmin/+ mice. As an important clinical correlate, human colon cancer samples expressed lower levels of NLRX1 than healthy controls in multiple patient cohorts. These data implicate anti-IL6R as a potential personalized therapy for colon cancers with reduced NLRX1.

  8. Impact of SNPs on CpG Islands in the MYC and HRAS oncogenes and in a wide variety of tumor suppressor genes: A multi-cancer approach.

    Science.gov (United States)

    Samy, Mohammad D; Yavorski, John M; Mauro, James A; Blanck, George

    2016-06-17

    Single nucleotide polymorphisms (SNPs) that occur within CpG Islands may lead to increased hypermethylation if a SNP allele has the potential to form a CpG dinucleotide, as well as potentially lead to hypomethylation if a SNP allele eliminates a CpG dinucleotide. We analyzed CpG-related SNP allele frequencies in whole genome sequences (WGS) across 5 TCGA cancer datasets, thereby exploiting a more recent appreciation for signaling pathway degeneracy in cancer. The cancer data sets were analyzed for SNPs in CpG islands associated with the oncogenes, HRAS and MYC, and in the CpG islands associated with the tumor suppressor genes, APC, DCC, and RB1. We determined that one SNP allele (rs3824120) in a CpG island associated with MYC which eliminated a CpG was more common in the cancer datasets than in the 100Genomes databases (p < 0.01). For HRAS, 2 SNP alleles (rs112690925, rs7939028) that created CpG's occurred significantly less frequently in the cancer data sets than in the general SNP databases (e.g., rs7939028, p < 0.0002, in comparison with AllSNPs(142)). Also, one SNP allele (rs4940177) that created a CpG in a CpG island associated with the DCC tumor suppressor gene, was more common in the cancer datasets (p < 0.0007). To understand a broader picture of the potential of SNP alleles to create CpG's in CpG islands of tumor suppressor genes, we developed a scripted algorithm to assess the SNP alleles associated with the CpG islands of 43 tumor suppressor genes. The following tumor suppressor genes have the possibility of significant, percent increases in their CpG counts, depending on which SNP allele(s) is present: VHL, BRCA1, BRCA2, CHEK2, PTEN and RB1.

  9. The Tumor Suppressor Actions of the Vitamin D Receptor in Skin

    Science.gov (United States)

    2013-08-01

    Lausanne) 3 (2012) 58. [ [ skin tumors. (A) The whole body of DKO mouse shows pigmentation (arrow) and graph shows the increased rate (%) of skin tumor...maximum within hours.6–8 Both the degree of epidermal pigmentation and the intensity of exposure correlate with the time required to achieve this maximal...vitamin D control antimicrobial peptide expression and susceptibility to bacterial skin infection. Sci Transl Med. 2012; 4:135ra166. 57. Barnfield PC

  10. FoxO3a governs early microglial proliferation and employs mitochondrial depolarization with caspase 3, 8, and 9 cleavage during oxidant induced apoptosis.

    Science.gov (United States)

    Shang, Yan Chen; Chong, Zhao Zhong; Hou, Jinling; Maiese, Kenneth

    2009-11-01

    Microglia of the central nervous system have a dual role in the ability to influence the survival of neighboring cells. During inflammatory cell activation, microglia can lead to the disposal of toxic cellular products and permit tissue regeneration, but microglia also may lead to cellular destruction with phagocytic removal. For these reasons, it is essential to elucidate not only the underlying pathways that control microglial activation and proliferation, but also the factors that determine microglial survival. In this regard, we investigated in the EOC 2 microglial cell line with an oxygen-glucose deprivation (OGD) injury model of oxidative stress the role of the "O" class forkhead transcription factor FoxO3a that in some scenarios is closely linked to immune system function. We demonstrate that FoxO3a is a necessary element in the control of early and late apoptotic injury programs that involve membrane phosphatidylserine externalization and nuclear DNA degradation, since transient knockdown of FoxO3a in microglia preserves cellular survival 24 hours following OGD exposure. However, prior to the onset of apoptotic injury, FoxO3a facilitates the activation and proliferation of microglia as early as 3 hours following OGD exposure that occurs in conjunction with the trafficking of the unphosphorylated and active post-translational form of FoxO3a from the cytoplasm to the cell nucleus. FoxO3a also can modulate apoptotic mitochondrial signal transduction pathways in microglia, since transient knockdown of FoxO3a prevents mitochondrial membrane depolarization as well as the release of cytochrome c during OGD. Control of this apoptotic cascade also extends to progressive caspase activation as early as 1 hour following OGD exposure. The presence of FoxO3a is necessary for the expression of cleaved (active) caspase 3, 8, and 9, since loss of FoxO3a abrogates the induction of caspase activity. Interestingly, elimination of FoxO3a reduced caspase 9 activity to a lesser extent than that noted with caspase 3 and 8 activities, suggesting that FoxO3a in relation to caspase 9 may be more reliant upon other signal transduction pathways potentially independent from caspase 3 and 8.

  11. Neurofibromatosis type 2 tumor suppressor protein, NF2, induces proteasome-mediated degradation of JC virus T-antigen in human glioblastoma.

    Directory of Open Access Journals (Sweden)

    Sarah Beltrami

    Full Text Available Neurofibromatosis type 2 protein (NF2 has been shown to act as tumor suppressor primarily through its functions as a cytoskeletal scaffold. However, NF2 can also be found in the nucleus, where its role is less clear. Previously, our group has identified JC virus (JCV tumor antigen (T-antigen as a nuclear binding partner for NF2 in tumors derived from JCV T-antigen transgenic mice. The association of NF2 with T-antigen in neuronal origin tumors suggests a potential role for NF2 in regulating the expression of the JCV T-antigen. Here, we report that NF2 suppresses T-antigen protein expression in U-87 MG human glioblastoma cells, which subsequently reduces T-antigen-mediated regulation of the JCV promoter. When T-antigen mRNA was quantified, it was determined that increasing expression of NF2 correlated with an accumulation of T-antigen mRNA; however, a decrease in T-antigen at the protein level was observed. NF2 was found to promote degradation of ubiquitin bound T-antigen protein via a proteasome dependent pathway concomitant with the accumulation of the JCV early mRNA encoding T-antigen. The interaction between T-antigen and NF2 maps to the FERM domain of NF2, which has been shown previously to be responsible for its tumor suppressor activity. Co-immunoprecipitation assays revealed a ternary complex among NF2, T-antigen, and the tumor suppressor protein, p53 within a glioblastoma cell line. Further, these proteins were detected in various degrees in patient tumor tissue, suggesting that these associations may occur in vivo. Collectively, these results demonstrate that NF2 negatively regulates JCV T-antigen expression by proteasome-mediated degradation, and suggest a novel role for NF2 as a suppressor of JCV T-antigen-induced cell cycle regulation.

  12. The role of UV induced lesions in skin carcinogenesis: an overview of oncogene and tumor suppressor gene modifications in xeroderma pigmentosum skin tumors

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    Daya-Grosjean, Leela [Laboratory of Genetic Instability and Cancer, UPR2169 CNRS, IFR 54, Institut Gustave Roussy, 39, rue Camille Desmoulins, 94805 Villejuif Cedex (France)]. E-mail: daya@igr.fr; Sarasin, Alain [Laboratory of Genetic Instability and Cancer, UPR2169 CNRS, IFR 54, Institut Gustave Roussy, 39, rue Camille Desmoulins, 94805 Villejuif Cedex (France)

    2005-04-01

    Xeroderma pigmentosum (XP), a rare hereditary syndrome, is characterized by a hypersensitivity to solar irradiation due to a defect in nucleotide excision repair resulting in a predisposition to squamous and basal cell carcinomas as well as malignant melanomas appearing at a very early age. The mutator phenotype of XP cells is evident by the higher levels of UV specific modifications found in key regulatory genes in XP skin tumors compared to those in the same tumor types from the normal population. Thus, XP provides a unique model for the study of unrepaired DNA lesions, mutations and skin carcinogenesis. The high level of ras oncogene activation, Ink4a-Arf and p53 tumor suppressor gene modifications as well as alterations of the different partners of the mitogenic sonic hedgehog signaling pathway (patched, smoothened and sonic hedgehog), characterized in XP skin tumors have clearly demonstrated the major role of the UV component of sunlight in the development of skin tumors. The majority of the mutations are C to T or tandem CC to TT UV signature transitions, occurring at bipyrimidine sequences, the specific targets of UV induced lesions. These characteristics are also found in the same genes modified in sporadic skin cancers but with lower frequencies confirming the validity of studying the XP model. The knowledge gained by studying XP tumors has given us a greater perception of the contribution of genetic predisposition to cancer as well as the consequences of the many alterations which modulate the activities of different genes affecting crucial pathways vital for maintaining cell homeostasis.

  13. Analysis of the Mitogen-activated protein kinase kinase 4 (MAP2K4 tumor suppressor gene in ovarian cancer

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    Ryland Georgina L

    2011-05-01

    Full Text Available Abstract Background MAP2K4 is a putative tumor and metastasis suppressor gene frequently found to be deleted in various cancer types. We aimed to conduct a comprehensive analysis of this gene to assess its involvement in ovarian cancer. Methods We screened for mutations in MAP2K4 using High Resolution Melt analysis of 149 primary ovarian tumors and methylation at the promoter using Methylation-Specific Single-Stranded Conformation Polymorphism analysis of 39 tumors. We also considered the clinical impact of changes in MAP2K4 using publicly available expression and copy number array data. Finally, we used siRNA to measure the effect of reducing MAP2K4 expression in cell lines. Results In addition to 4 previously detected homozygous deletions, we identified a homozygous 16 bp truncating deletion and a heterozygous 4 bp deletion, each in one ovarian tumor. No promoter methylation was detected. The frequency of MAP2K4 homozygous inactivation was 5.6% overall, and 9.8% in high-grade serous cases. Hemizygous deletion of MAP2K4 was observed in 38% of samples. There were significant correlations of copy number and expression in three microarray data sets. There was a significant correlation between MAP2K4 expression and overall survival in one expression array data set, but this was not confirmed in an independent set. Treatment of JAM and HOSE6.3 cell lines with MAP2K4 siRNA showed some reduction in proliferation. Conclusions MAP2K4 is targeted by genetic inactivation in ovarian cancer and restricted to high grade serous and endometrioid carcinomas in our cohort.

  14. Generation of Foxo3-targeted Mice by Injection of mRNAs Encoding Transcription Activator-like Effector Nucleases (TALENs) into Zygotes.

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    Zhu, P; Liu, Q; Liu, S; Su, X; Feng, W; Lei, X; Liu, J; Cui, K; Huang, B; Shi, D

    2015-06-01

    In this study, for exploring the mechanism of forkhead box O3(Foxo3) participating in regulation of the activation of primordial oocytes, Foxo3-targeted mice were generated by injection of mRNAs encoding transcription activator-like effector nucleases (TALENs) into mouse zygotes. The TALEN sites were designed with high conservative homologous region among pig, bovine, buffalo and mouse by commercial bio-companies. The TALENs mutagenic non-homologous end-joining (NHEJ) repair activity were determined to be 31.3% in human embryonic kidney 293T (HEK-293T) cells by dual luciferase reporter assay system. Then, we firstly injected TALEN-mRNAs into the cytoplasm of mouse zygotes by micromanipulation, and four of 48 mouse blastocysts were identified as mutation by sequencing. Subsequently, by the method of TALEN-mRNAs injected into the zygotes with pronucleus micromanipulation technique, we obtained seven Foxo3 mutants of 20 FVB/NJ backgrounds mice which were Foxo3-independent alleles with frameshift and deletion mutations. It was very interesting that all seven were heterozygous mutants (Foxo3(-/+) ), and the gene mutagenesis rates of the mice reached 35%. The five Foxo3 mutant females were all infertile in the following 6 months after birth. The histological examination results showed that there were rare primordial follicles and primary follicles in the ovary of Foxo3 mutant compared to that of wide-type female mice. Moreover, one of two mutant males was subfertile and another was fertile normally. Those results suggested that the mutant of Foxo3 severely affected the fertile ability of female and perhaps male in some degree; furthermore, an even more efficient TALENs-based gene mutation method has been established to be poised to revolutionize the study of mouse and other species genetics.

  15. Carbocysteine counteracts the effects of cigarette smoke on cell growth and on the SIRT1/FoxO3 axis in bronchial epithelial cells.

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    Pace, E; Di Vincenzo, S; Ferraro, M; Bruno, A; Dino, P; Bonsignore, M R; Battaglia, S; Saibene, F; Lanata, L; Gjomarkaj, M

    2016-08-01

    Cigarette smoke may accelerate cellular senescence by increasing oxidative stress. Altered proliferation and altered expression of anti-aging factors, including SIRT1 and FoxO3, characterise cellular senescence. The effects of carbocysteine on the SIRT1/FoxO3 axis and on downstream molecular mechanisms in human bronchial epithelial cells exposed to cigarette smoke are largely unknown. Aim of this study was to explore whether carbocysteine modulated SIRT1/FoxO3 axis, and downstream molecular mechanisms associated to cellular senescence, in a bronchial epithelial cell line (16-HBE) exposed to cigarette smoke. 16HBE cells were stimulated with/without cigarette smoke extracts (CSE) and carbocysteine. Flow cytometry and clonogenic assay were used to assess cell proliferation; western blot analysis was used for assessing nuclear expression of SIRT1 and FoxO3. The nuclear co-localization of SIRT1 and FoxO3 was assessed by fluorescence microscopy. Beta galactosidase (a senescence marker) and SIRT1 activity were assessed by specific staining and colorimetric assays, respectively. ChiP Assay and flow cytometry were used for assessing survivin gene regulation and protein expression, respectively. CSE decreased cell proliferation, the nuclear expression of SIRT1 and FoxO3 and increased beta galactosidase staining. CSE, reduced SIRT1 activity and FoxO3 localization on survivin promoter thus increasing survivin expression. In CSE stimulated bronchial epithelial cells carbocysteine reverted these phenomena by increasing cell proliferation, and SIRT1 and FoxO3 nuclear expression, and by reducing beta galactosidase staining and survivin expression. The study shows for the first time that carbocysteine may revert some senescence processes induced by oxidative stress due to cigarette smoke exposure. Copyright © 2016 Elsevier Inc. All rights reserved.

  16. HOXB13, a target of DNMT3B, is methylated at an upstream CpG island, and functions as a tumor suppressor in primary colorectal tumors.

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    Kalpana Ghoshal

    Full Text Available BACKGROUND: A hallmark of cancer cells is hypermethylation of CpG islands (CGIs, which probably arises from upregulation of one or more DNA methyltransferases. The purpose of this study was to identify the targets of DNMT3B, an essential DNA methyltransferase in mammals, in colon cancer. METHODOLOGY/PRINCIPAL FINDINGS: Chromatin immunoprecipitation with DNMT3B specific antibody followed by CGI microarray identified genes with or without CGIs, repeat elements and genomic contigs in RKO cells. ChIP-Chop analysis showed that the majority of the target genes including P16, DCC, DISC1, SLIT1, CAVEOLIN1, GNA11, TBX5, TBX18, HOXB13 and some histone variants, that harbor CGI in their promoters, were methylated in multiple colon cancer cell lines but not in normal colon epithelial cells. Further, these genes were reactivated in RKO cells after treatment with 5-aza-2'-deoxycytidine, a DNA hypomethylating agent. COBRA showed that the CGIs encompassing the promoter and/or coding region of DCC, TBX5, TBX18, SLIT1 were methylated in primary colorectal tumors but not in matching normal colon tissues whereas GNA11 was methylated in both. MassARRAY analysis demonstrated that the CGI located approximately 4.5 kb upstream of HOXB13 +1 site was tumor-specifically hypermethylated in primary colorectal cancers and cancer cell lines. HOXB13 upstream CGI was partially hypomethylated in DNMT1(-/- HCT cells but was almost methylation free in cells lacking both DNMT1 and DNMT3B. Analysis of tumor suppressor properties of two aberrantly methylated transcription factors, HOXB13 and TBX18, revealed that both inhibited growth and clonogenic survival of colon cancer cells in vitro, but only HOXB13 abolished tumor growth in nude mice. CONCLUSIONS/SIGNIFICANCE: This is the first report that identifies several important tumor suppressors and transcription factors as direct DNMT3B targets in colon cancer and as potential biomarkers for this cancer. Further, this study shows that

  17. MicroRNA-320a acts as a tumor suppressor by targeting BCR/ABL oncogene in chronic myeloid leukemia.

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    Xishan, Zhu; Ziying, Lin; Jing, Du; Gang, Liu

    2015-01-01

    Accumulating evidences demonstrated that the induction of epithelial-mesenchymal transition (EMT) and aberrant expression of microRNAs (miRNAs) are associated with tumorigenesis, tumor progression, metastasis and relapse in cancers, including chronic myeloid leukemia (CML). We found that miR-320a expression was reduced in K562 and in CML cancer stem cells. Moreover, we found that miR-320a inhibited K562 cell migration, invasion, proliferation and promoted apoptosis by targeting BCR/ABL oncogene. As an upstream regulator of BCR/ABL, miR-320a directly targets BCR/ABL. The enhanced expression of miR-320a inhibited the phosphorylation of PI3K, AKT and NF-κB; however, the expression of phosphorylated PI3K, AKT and NF-κB were restored by the overexpression of BCR/ABL. In K562, infected with miR-320a or transfected with SiBCR/ABL, the protein levels of fibronectin, vimentin, and N-cadherin were decreased, but the expression of E-cadherin was increased. The expression of mesenchymal markers in miR-320a-expressing cells was restored to normal levels by the restoration of BCR/ABL expression. Generally speaking, miR-320a acts as a novel tumor suppressor gene in CML and miR-320a can decrease migratory, invasive, proliferative and apoptotic behaviors, as well as CML EMT, by attenuating the expression of BCR/ABL oncogene.

  18. The tumor suppressor p53 fine-tunes reactive oxygen species levels and neurogenesis via PI3 kinase signaling.

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    Forsberg, Kirsi; Wuttke, Anja; Quadrato, Giorgia; Chumakov, Peter M; Wizenmann, Andrea; Di Giovanni, Simone

    2013-09-01

    Mounting evidence points to a role for endogenous reactive oxygen species (ROS) in cell signaling, including in the control of cell proliferation, differentiation, and fate. However, the function of ROS and their molecular regulation in embryonic mouse neural progenitor cells (eNPCs) has not yet been clarified. Here, we describe that physiological ROS are required for appropriate timing of neurogenesis in the developing telencephalon in vivo and in cultured NPCs, and that the tumor suppressor p53 plays a key role in the regulation of ROS-dependent neurogenesis. p53 loss of function leads to elevated ROS and early neurogenesis, while restoration of p53 and antioxidant treatment partially reverse the phenotype associated with premature neurogenesis. Furthermore, we describe that the expression of a number of neurogenic and oxidative stress genes relies on p53 and that both p53 and ROS-dependent induction of neurogenesis depend on PI3 kinase/phospho-Akt signaling. Our results suggest that p53 fine-tunes endogenous ROS levels to ensure the appropriate timing of neurogenesis in eNPCs. This may also have implications for the generation of tumors of neurodevelopmental origin.

  19. The Oncogenic STP Axis Promotes Triple-Negative Breast Cancer via Degradation of the REST Tumor Suppressor

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    Kristen L. Karlin

    2014-11-01

    Full Text Available Defining the molecular networks that drive breast cancer has led to therapeutic interventions and improved patient survival. However, the aggressive triple-negative breast cancer subtype (TNBC remains recalcitrant to targeted therapies because its molecular etiology is poorly defined. In this study, we used a forward genetic screen to discover an oncogenic network driving human TNBC. SCYL1, TEX14, and PLK1 (“STP axis” cooperatively trigger degradation of the REST tumor suppressor protein, a frequent event in human TNBC. The STP axis induces REST degradation by phosphorylating a conserved REST phospho-degron and bridging REST interaction with the ubiquitin-ligase βTRCP. Inhibition of the STP axis leads to increased REST protein levels and impairs TNBC transformation, tumor progression, and metastasis. Expression of the STP axis correlates with low REST protein levels in human TNBCs and poor clinical outcome for TNBC patients. Our findings demonstrate that the STP-REST axis is a molecular driver of human TNBC.

  20. YThe BigH3 Tumor Suppressor Gene in Radiation-Induced Malignant Transformation of Human Bronchial Epithelial Cells

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    Zhao, Y.; Shao, G.; Piao, C.; Hei, T.

    Carcinogenesis is a multi-stage process with sequences of genetic events governing the phenotypic expression of a series of transformation steps leading to the development of metastatic cancer Previous studies from this laboratory have identified a 7 fold down- regulation of the novel tumor suppressor Big-h3 among radiation induced tumorigenic BEP2D cells Furthermore ectopic re-expression of this gene suppresses tumorigenic phenotype and promotes the sensitivity of these tumor cells to etoposide-induced apoptosis To extend these studies using a genomically more stable bronchial cell line we ectopically expresses the catalytic subunit of telomerase hTERT in primary human small airway epithelial SAE cells and generated several clonal cell lines that have been continuously in culture for more than 250 population doublings and are considered immortal Comparably-treated control SAE cells infected with only the viral vector senesced after less than 10 population doublings The immortalized clones demonstrated anchorage dependent growth and are non-tumorigenic in nude mice These cells show no alteration in the p53 gene but a decrease in p16 expression Exponentially growing SAEh cells were exposed to graded doses of 1 GeV nucleon of 56 Fe ions accelerated at the Brookhaven National Laboratory Irradiated cells underwent gradual phenotypic alterations after extensive in vitro cultivation Transformed cells developed through a series of successive steps before becoming anchorage independent in semisolid medium These findings indicate

  1. Waking up dormant tumor suppressor genes with zinc fingers, TALEs and the CRISPR/dCas9 system

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    Garcia-Bloj, Benjamin; Moses, Colette; Sgro, Agustin; Plani-Lam, Janice; Arooj, Mahira; Duffy, Ciara; Thiruvengadam, Shreyas; Sorolla, Anabel; Rashwan, Rabab; Mancera, Ricardo L.; Leisewitz, Andrea; Swift-Scanlan, Theresa; Corvalan, Alejandro H.; Blancafort, Pilar

    2016-01-01

    The aberrant epigenetic silencing of tumor suppressor genes (TSGs) plays a major role during carcinogenesis and regaining these dormant functions by engineering of sequence-specific epigenome editing tools offers a unique opportunity for targeted therapies. However, effectively normalizing the expression and regaining tumor suppressive functions of silenced TSGs by artificial transcription factors (ATFs) still remains a major challenge. Herein we describe novel combinatorial strategies for the potent reactivation of two class II TSGs, MASPIN and REPRIMO, in cell lines with varying epigenetic states, using the CRISPR/dCas9 associated system linked to a panel of effector domains (VP64, p300, VPR and SAM complex), as well as with protein-based ATFs, Zinc Fingers and TALEs. We found that co-delivery of multiple effector domains using a combination of CRISPR/dCas9 and TALEs or SAM complex maximized activation in highly methylated promoters. In particular, CRISPR/dCas9 VPR with SAM upregulated MASPIN mRNA (22,145-fold change) in H157 lung cancer cells, with accompanying re-expression of MASPIN protein, which led to a concomitant inhibition of cell proliferation and induction of apoptotic cell death. Consistently, CRISPR/dCas9 VP64 with SAM upregulated REPRIMO (680-fold change), which led to phenotypic reprogramming in AGS gastric cancer cells. Altogether, our results outlined novel sequence-specific, combinatorial epigenome editing approaches to reactivate highly methylated TSGs as a promising therapy for cancer and other diseases. PMID:27528034

  2. Waking up dormant tumor suppressor genes with zinc fingers, TALEs and the CRISPR/dCas9 system.

    Science.gov (United States)

    Garcia-Bloj, Benjamin; Moses, Colette; Sgro, Agustin; Plani-Lam, Janice; Arooj, Mahira; Duffy, Ciara; Thiruvengadam, Shreyas; Sorolla, Anabel; Rashwan, Rabab; Mancera, Ricardo L; Leisewitz, Andrea; Swift-Scanlan, Theresa; Corvalan, Alejandro H; Blancafort, Pilar

    2016-09-13

    The aberrant epigenetic silencing of tumor suppressor genes (TSGs) plays a major role during carcinogenesis and regaining these dormant functions by engineering of sequence-specific epigenome editing tools offers a unique opportunity for targeted therapies. However, effectively normalizing the expression and regaining tumor suppressive functions of silenced TSGs by artificial transcription factors (ATFs) still remains a major challenge. Herein we describe novel combinatorial strategies for the potent reactivation of two class II TSGs, MASPIN and REPRIMO, in cell lines with varying epigenetic states, using the CRISPR/dCas9 associated system linked to a panel of effector domains (VP64, p300, VPR and SAM complex), as well as with protein-based ATFs, Zinc Fingers and TALEs. We found that co-delivery of multiple effector domains using a combination of CRISPR/dCas9 and TALEs or SAM complex maximized activation in highly methylated promoters. In particular, CRISPR/dCas9 VPR with SAM upregulated MASPIN mRNA (22,145-fold change) in H157 lung cancer cells, with accompanying re-expression of MASPIN protein, which led to a concomitant inhibition of cell proliferation and induction of apoptotic cell death. Consistently, CRISPR/dCas9 VP64 with SAM upregulated REPRIMO (680-fold change), which led to phenotypic reprogramming in AGS gastric cancer cells. Altogether, our results outlined novel sequence-specific, combinatorial epigenome editing approaches to reactivate highly methylated TSGs as a promising therapy for cancer and other diseases.

  3. TMSB4Y is a candidate tumor suppressor on the Y chromosome and is deleted in male breast cancer.

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    Wong, Hong Yuen; Wang, Grace M; Croessmann, Sarah; Zabransky, Daniel J; Chu, David; Garay, Joseph P; Cidado, Justin; Cochran, Rory L; Beaver, Julia A; Aggarwal, Anita; Liu, Min-Ling; Argani, Pedram; Meeker, Alan; Hurley, Paula J; Lauring, Josh; Park, Ben Ho

    2015-12-29

    Male breast cancer comprises less than 1% of breast cancer diagnoses. Although estrogen exposure has been causally linked to the development of female breast cancers, the etiology of male breast cancer is unclear. Here, we show via fluorescence in situ hybridization (FISH) and droplet digital PCR (ddPCR) that the Y chromosome was clonally lost at a frequency of ~16% (5/31) in two independent cohorts of male breast cancer patients. We also show somatic loss of the Y chromosome gene TMSB4Y in a male breast tumor, confirming prior reports of loss at this locus in male breast cancers. To further understand the function of TMSB4Y, we created inducible cell lines of TMSB4Y in the female human breast epithelial cell line MCF-10A. Expression of TMSB4Y resulted in aberrant cellular morphology and reduced cell proliferation, with a corresponding reduction in the fraction of metaphase cells. We further show that TMSB4Y interacts directly with β-actin, the main component of the actin cytoskeleton and a cell cycle modulator. Taken together, our results suggest that clonal loss of the Y chromosome may contribute to male breast carcinogenesis, and that the TMSB4Y gene has tumor suppressor properties.

  4. In Vivo Assays for Assessing the Role of the Wilms' Tumor Suppressor 1 (Wt1) in Angiogenesis.

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    McGregor, Richard J; Ogley, R; Hadoke, Pwf; Hastie, Nicholas

    2016-01-01

    The Wilms' tumor suppressor gene (WT1) is widely expressed during neovascularization, but it is almost entirely absent in quiescent adult vasculature. However, in vessels undergoing angiogenesis, WT1 is dramatically upregulated. Studies have shown Wt1 has a role in both tumor and ischemic angiogenesis, but the mechanism of Wt1 action in angiogenic tissue remains to be elucidated. Here, we describe two methods for induction of in vivo angiogenesis (subcutaneous sponge implantation, femoral artery ligation) that can be used to assess the influence of Wt1 on new blood vessel formation. Subcutaneously implanted sponges stimulate an inflammatory and fibrotic response including cell infiltration and angiogenesis. Femoral artery ligation creates ischemia in the distal hindlimb and produces an angiogenic response to reperfuse the limb which can be quantified in vivo by laser Doppler flowmetry. In both of these models, the role of Wt1 in the angiogenic process can be assessed using histological/immunohistochemical staining, molecular analysis (qPCR) and flow cytometry. Furthermore, combined with suitable genetic modifications, these models can be used to explore the causal relationship between Wt1 expression and angiogenesis and to trace the lineage of cells expressing Wt1. This approach will help to clarify the importance of Wt1 in regulating neovascularization in the adult, and its potential as a therapeutic target.

  5. JMJD2A Promotes Cellular Transformation by Blocking Cellular Senescence through Transcriptional Repression of the Tumor Suppressor CHD5

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    Frédérick A. Mallette

    2012-11-01

    Full Text Available Senescence is a cellular response preventing tumorigenesis. The Ras oncogene is frequently activated or mutated in human cancers, but Ras activation is insufficient to transform primary cells. In a search for cooperating oncogenes, we identify the lysine demethylase JMJD2A/KDM4A. We show that JMJD2A functions as a negative regulator of Ras-induced senescence and collaborates with oncogenic Ras to promote cellular transformation by negatively regulating the p53 pathway. We find CHD5, a known tumor suppressor regulating p53 activity, as a target of JMJD2A. The expression of JMJD2A inhibits Ras-mediated CHD5 induction leading to a reduced activity of the p53 pathway. In addition, we show that JMJD2A is overexpressed in mouse and human lung cancers. Depletion of JMJD2A in the human lung cancer cell line A549 bearing an activated K-Ras allele triggers senescence. We propose that JMJD2A is an oncogene that represents a target for Ras-expressing tumors.

  6. Expression level of novel tumor suppressor gene FATS is associated with the outcome of node positive breast cancer

    Institute of Scientific and Technical Information of China (English)

    ZHANG Jun; GU Lin; ZHAO Lu-jun; ZHANG Xi-feng; QIU Li; LI Zheng

    2011-01-01

    Background Recently, we reported the identification of a previously uncharacterized and evolutionarily conserved gene, fragile-site associated tumor suppressor (FATS), at a frequently deleted region in irradiation (IR)-induced tumors.However, the role of FATS in breast cancer development and its clinical significance has not been defined. The aim of this study was to determine the role of FA7S in breast cancer development and to evaluate its clinical significance in breast cancer.Methods The expression level of FATS mRNA was determined in 106 breast carcinomas and 23 paired normal breast tissues using quantitative real time reverse transcription-polymerase chain reaction (RT-PCR). The relationship between FATS expression and clinicopathological parameters were also analyzed.Results The mRNA level of FATS was down-regulated in breast cancer compared with paired normal tissues. Low expression of FATS was correlated with high nuclear grade. There was a tendency to a favorable outcome for patients with high expression of FATS (P=0.346). However, low expression of FATS was associated with poor outcome of breast cancer patients with node positive (P=0.011). Furthermore, the mRNA level of FATS showed an independent value in predicting the outcome of breast cancer patients with positive lymph nodes.Conclusion FATS is involved in the carcinogenesis and development of breast cancer and could be a potential biomarker and prognostic factor for breast cancer therapy.

  7. Tumor suppressor function of Syk in human MCF10A in vitro and normal mouse mammary epithelium in vivo.

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    You Me Sung

    Full Text Available The normal function of Syk in epithelium of the developing or adult breast is not known, however, Syk suppresses tumor growth, invasion, and metastasis in breast cancer cells. Here, we demonstrate that in the mouse mammary gland, loss of one Syk allele profoundly increases proliferation and ductal branching and invasion of epithelial cells through the mammary fat pad during puberty. Mammary carcinomas develop by one year. Syk also suppresses proliferation and invasion in vitro. siRNA or shRNA knockdown of Syk in MCF10A breast epithelial cells dramatically increased proliferation, anchorage independent growth, cellular motility, and invasion, with formation of functional, extracellular matrix-degrading invadopodia. Morphological and gene microarray analysis following Syk knockdown revealed a loss of luminal and differentiated epithelial features with epithelial to mesenchymal transition and a gain in invadopodial cell surface markers CD44, CD49F, and MMP14. These results support the role of Syk in limiting proliferation and invasion of epithelial cells during normal morphogenesis, and emphasize the critical role of Syk as a tumor suppressor for breast cancer. The question of breast cancer risk following systemic anti-Syk therapy is raised since only partial loss of Syk was sufficient to induce mammary carcinomas.

  8. Frequent silencing of the candidate tumor suppressor TRIM58 by promoter methylation in early-stage lung adenocarcinoma.

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    Kajiura, Koichiro; Masuda, Kiyoshi; Naruto, Takuya; Kohmoto, Tomohiro; Watabnabe, Miki; Tsuboi, Mitsuhiro; Takizawa, Hiromitsu; Kondo, Kazuya; Tangoku, Akira; Imoto, Issei

    2017-01-10

    In this study, we aimed to identify novel drivers that would be epigenetically altered through aberrant methylation in early-stage lung adenocarcinoma (LADC), regardless of the presence or absence of tobacco smoking-induced epigenetic field defects. Through genome-wide screening for aberrantly methylated CpG islands (CGIs) in 12 clinically uniform, stage-I LADC cases affecting six non-smokers and six smokers, we identified candidate tumor-suppressor genes (TSGs) inactivated by hypermethylation. Through systematic expression analyses of those candidates in panels of additional tumor samples and cell lines treated or not treated with 5-aza-deoxycitidine followed by validation analyses of cancer-specific silencing by CGI hypermethylation using a public database, we identified TRIM58 as the most prominent candidate for TSG. TRIM58 was robustly silenced by hypermethylation even in early-stage primary LADC, and the restoration of TRIM58 expression in LADC cell lines inhibited cell growth in vitro and in vivo in anchorage-dependent and -independent manners. Our findings suggest that aberrant inactivation of TRIM58 consequent to CGI hypermethylation might stimulate the early carcinogenesis of LADC regardless of smoking status; furthermore, TRIM58 methylation might be a possible early diagnostic and epigenetic therapeutic target in LADC.

  9. The Neurofibromatosis 2 Tumor Suppressor Gene Product, Merlin, Regulates Human Meningioma Cell Growth by Signaling through YAP

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    Katherine Striedinger

    2008-11-01

    Full Text Available Neurofibromatosis type 2 (NF2 is an autosomal dominant disorder characterized by the occurrence of schwannomas and meningiomas. Several studies have examined the ability of the NF2 gene product, merlin, to function as a tumor suppressor in diverse cell types; however, little is known about merlin growth regulation in meningiomas. In Drosophila, merlin controls cell proliferation and apoptosis by signaling through the Hippo pathway to inhibit the function of the transcriptional coactivator Yorkie. The Hippo pathway is conserved in mammals. On the basis of these observations, we developed human meningioma cell lines matched for merlin expression to evaluate merlin growth regulation and investigate the relationship between NF2 status and Yes-associated protein (YAP, the mammalian homolog of Yorkie. NF2 loss in meningioma cells was associated with loss of contact-dependent growth inhibition, enhanced anchorage-independent growth and increased cell proliferation due to increased S-phase entry. In addition, merlin loss in both meningioma cell lines and primary tumors resulted in increased YAP expression and nuclear localization. Finally, siRNA-mediated reduction of YAP in NF2-deficient meningioma cells rescued the effects of merlin loss on cell proliferation and S-phase entry. Collectively, these results represent the first demonstration that merlin regulates cell growth in human cancer cells by suppressing YAP.

  10. hsa-mir-181a and hsa-mir-181b function as tumor suppressors in human glioma cells.

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    Shi, Lei; Cheng, Zihao; Zhang, Junxia; Li, Rui; Zhao, Peng; Fu, Zhen; You, Yongping

    2008-10-21

    MicroRNAs (miRNAs) are small noncoding RNA molecules that regulate protein expression by cleaving or repressing the translation of target mRNAs. In mammal animals, their function mainly represses the target mRNAs transcripts via imperfectly complementary to the 3' UTR of target mRNAs. Several miRNAs have been recently reported to be involved in modulation of glioma development, especially some up-regulated miRNA, such as hsa-miR-21 and hsa-miR-221. However, here we reported that the down-regulated hsa-miR-181a and hsa-miR-181b of hsa-miR-181 family were also involved in oncogenesis of glioma. Our studies showed that hsa-miR-181a and hsa-miR-181b functioned as tumor suppressors which triggered growth inhibition, induced apoptosis and inhibited invasion in glioma cells. Furthermore, the tumor-suppressive effect of hsa-miR-181b in glioma cells was more apparent than the effect of hsa-miR-181a. These findings suggest aberrantly down-regulated hsa-miR-181a and hsa-miR-181b may be critical factors that contribute to malignant appearance in human gliomas.

  11. Quercetin induces apoptosis and cell cycle arrest in triple-negative breast cancer cells through modulation of Foxo3a activity.

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    Nguyen, Lich Thi; Lee, Yeon-Hee; Sharma, Ashish Ranjan; Park, Jong-Bong; Jagga, Supriya; Sharma, Garima; Lee, Sang-Soo; Nam, Ju-Suk

    2017-03-01

    Quercetin, a plant-derived flavonoid found in fruits, vegetables and tea, has been known to possess bioactive properties such as anti-oxidant, anti-inflammatory and anti-cancer. In this study, anti-cancer effect of quercetin and its underlying mechanisms in triple-negative breast cancer cells was investigated. MTT assay showed that quercetin reduced breast cancer cell viability in a time and dose dependent manner. For this, quercetin not only increased cell apoptosis but also inhibited cell cycle progression. Moreover, quercetin increased FasL mRNA expression and p51, p21 and GADD45 signaling activities. We also observed that quercetin induced protein level, transcriptional activity and nuclear translocation of Foxo3a. Knockdown of Foxo3a caused significant reduction in the effect of quercetin on cell apoptosis and cell cycle arrest. In addition, treatment of JNK inhibitor (SP 600125) abolished quercetin-stimulated Foxo3a activity, suggesting JNK as a possible upstream signaling in regulation of Foxo3a activity. Knockdown of Foxo3a and inhibition of JNK activity reduced the signaling activities of p53, p21 and GADD45, triggered by quercetin. Taken together, our study suggests that quercetin induces apoptosis and cell cycle arrest via modification of Foxo3a signaling in triple-negative breast cancer cells.

  12. FoxO3a mediates transforming growth factor-beta1-induced apoptosis in FaO rat hepatoma cells.

    Science.gov (United States)

    Kim, Byung-Chul

    2008-10-31

    FoxO3a is a member of the forkhead box class O (FoxO) transcription factor family and an important regulator of apoptosis. This work aimed to elucidate the involvement of FoxO3a in transforming growth factor-beta1 (TGF-beta1)-induced apoptosis in FaO rat hepatoma cells. TGF-beta1 caused a time-dependent activation of FoxO3a and a subsequent increase in FoxO response-element-containing luciferase reporter activity, which was Akt-sensitive. The FaO cells stably transfected with a wild type FoxO3a were more susceptible to the formation of apoptotic bodies, populations of sub-G1 apoptotic cells, and collapse of the mitochondrial-membrane potential triggered by TGF-beta1. In contrast, transfection with small-interfering RNA (siRNA) oligonucleotide specific for FoxO3a significantly inhibited caspase activation in FaO cells treated with TGF-beta1. It thus appears that FoxO3a plays a crucial mediatory role in the TGF-beta1 signaling pathway leading to apoptosis.

  13. Quercetin induces apoptosis and cell cycle arrest in triple-negative breast cancer cells through modulation of Foxo3a activity

    Science.gov (United States)

    Nguyen, Lich Thi; Lee, Yeon-Hee; Sharma, Ashish Ranjan; Park, Jong-Bong; Jagga, Supriya; Sharma, Garima

    2017-01-01

    Quercetin, a plant-derived flavonoid found in fruits, vegetables and tea, has been known to possess bioactive properties such as anti-oxidant, anti-inflammatory and anti-cancer. In this study, anti-cancer effect of quercetin and its underlying mechanisms in triple-negative breast cancer cells was investigated. MTT assay showed that quercetin reduced breast cancer cell viability in a time and dose dependent manner. For this, quercetin not only increased cell apoptosis but also inhibited cell cycle progression. Moreover, quercetin increased FasL mRNA expression and p51, p21 and GADD45 signaling activities. We also observed that quercetin induced protein level, transcriptional activity and nuclear translocation of Foxo3a. Knockdown of Foxo3a caused significant reduction in the effect of quercetin on cell apoptosis and cell cycle arrest. In addition, treatment of JNK inhibitor (SP 600125) abolished quercetin-stimulated Foxo3a activity, suggesting JNK as a possible upstream signaling in regulation of Foxo3a activity. Knockdown of Foxo3a and inhibition of JNK activity reduced the signaling activities of p53, p21 and GADD45, triggered by quercetin. Taken together, our study suggests that quercetin induces apoptosis and cell cycle arrest via modification of Foxo3a signaling in triple-negative breast cancer cells. PMID:28280414

  14. MicroRNA-31 functions as an oncogenic microRNA in mouse and human lung cancer cells by repressing specific tumor suppressors

    DEFF Research Database (Denmark)

    Liu, Xi; Sempere, Lorenzo F; Ouyang, Haoxu;

    2010-01-01

    confirmed them as direct targets in human and mouse lung cancer cell lines. These targets included the tumor-suppressive genes large tumor suppressor 2 (LATS2) and PP2A regulatory subunit B alpha isoform (PPP2R2A), and expression of each was augmented by miR-31 knockdown. Their engineered repression...... normal and malignant human lung tissues. Together, these findings revealed that miR-31 acts as an oncogenic miRNA (oncomir) in lung cancer by targeting specific tumor suppressors for repression.......MicroRNAs (miRNAs) regulate gene expression. It has been suggested that obtaining miRNA expression profiles can improve classification, diagnostic, and prognostic information in oncology. Here, we sought to comprehensively identify the miRNAs that are overexpressed in lung cancer by conducting mi...

  15. The milk protein α-casein functions as a tumor suppressor via activation of STAT1 signaling, effectively preventing breast cancer tumor growth and metastasis

    Science.gov (United States)

    Bonuccelli, Gloria; Castello-Cros, Remedios; Capozza, Franco; Martinez-Outschoorn, Ubaldo E.; Lin, Zhao; Tsirigos, Aristotelis; Xuanmao, Jiao; Whitaker-Menezes, Diana; Howell, Anthony; Lisanti, Michael P.; Sotgia, Federica

    2012-01-01

    Here, we identified the milk protein α-casein as a novel suppressor of tumor growth and metastasis. Briefly, Met-1 mammary tumor cells expressing α-casein showed a ~5-fold reduction in tumor growth and a near 10-fold decrease in experimental metastasis. To identify the molecular mechanism(s), we performed genome-wide transcriptional profiling. Interestingly, our results show that α-casein upregulates gene transcripts associated with interferon/STAT1 signaling and downregulates genes associated with “stemness.” These findings were validated by immunoblot and FACS analysis, which showed the upregulation and hyperactivation of STAT1 and a decrease in the number of CD44(+) “cancer stem cells.” These gene signatures were also able to predict clinical outcome in human breast cancer patients. Thus, we conclude that a lactation-based therapeutic strategy using recombinant α-casein would provide a more natural and non-toxic approach to the development of novel anticancer therapies. PMID:23047602

  16. [Analysis of loss of heterozygosity of the tumor suppressor genes p53 and BRCA1 in ovarial carcinomas].

    Science.gov (United States)

    Petrović, Bojana; Perović, Milica; Novaković, Ivana; Atanacković, Jasmina; Popović, Branka; Luković, Ljiljana; Petković, Spasoje

    2006-09-01

    Among the genes involved in ovarian carcinogenesis, there has been increased interest in tumor-suppressor genes p53 and BRCA1. Both of the genes make control of cell cycle, DNA repair and apoptosis. The p53 is a "genome guardian" inactivated in more than 50% of human cancers, while BRCA1 mutations are found mostly in breast and ovarian cancer. The aim of this investigation was to establish the frequency of loss of heterozygosity (LOH) in the regions of the genes p53 and BRCA1 in ovarian carcinomas, and to analyze the association of LOH with the disease stage and prognosis. We analyzed 20 patients with a confirmed diagnosis of epithelilal ovarian carcinoma. DNA for molecular-genetic analysis was extracted from the tumor tissue and blood as normal tissue of each person. Microsatellite markers of the regions of genes p53 and BRCA1 were amplified by PCR method. The determination of allelic status of microsatellites and detection of LOH was performed after PAA gel electroforesis. Both of the analyzed microsatellite markers were informative in 13/20 (65%) cases. In the region of gene p53, LOH was established in 4/13 (30.7%) tumors. One of them had histological gradus G1, one had gradus G2, and two of them had gradus G3, while all were with the International Federation of Gynecology and Obstetrics (FIGO) IIIc stage. In the region of gene BRCA1, LOH was detected in 5/13 (38.5%) tumors. Four of them had histological gradus G2, and one had gradus G3, while by the (FIGO) classification one was with stage Ib, one was with stage IIIb, while the three were with stage IlIc. LOH in both of the analyzed regions was detected in one tumor (7.70), with histological gradus G3 and the FIGO IIIc stage. The frequency of LOH in epthelial ovarian carcinomas was 30.7% and 38.5% for p53 and BRCA1 gene regions, respectively. Most of tumors with LOH had histological gradus G2 or G3, and the clinical FIGO stage IIIc, suggesting the association of this occurrence with a later phase of the disease.

  17. Analysis of loss of heterozygosity of the tumor suppressor genes p53 and BRCA1 in ovarial carcinomas

    Directory of Open Access Journals (Sweden)

    Luković Ljiljana

    2006-01-01

    Full Text Available Background/aim: Among the genes involved in ovarian carcinogenesis, there has been increased interest in tumor-suppressor genes p53 and BRCA1. Both of the genes make control of cell cycle, DNA repair and apoptosis. The p53 is a "genome guardian" inactivated in more than 50% of human cancers, while BRCA1 mutations are found mostly in breast and ovarian cancer. The aim of this investigation was to establish the frequency of loss of heterozygosity (LOH in the regions of the genes p53 and BRCA1 in ovarian carcinomas, and to analyze the association of LOH with the disease stage and prognosis. Methods. We analyzed 20 patients with a confirmed diagnosis of epithelilal ovarian carcinoma. DNA for molecular-genetic analysis was extracted from the tumor tissue and blood as normal tissue of each person. Microsatellite markers of the regions of genes p53 and BRCA1 were amplified by PCR method. The determination of allelic status of microsatellites and detection of LOH was performed after PAA gel electroforesis. Results. Both of the analyzed microsatellite markers were informative in 13/20 (65% cases. In the region of gene p53, LOH was established in 4/13 (30.7% tumors. One of them had histological gradus G1, one had gradus G2, and two of them had gradus G3, while all were with the International Federation of Gynecology and Obstetrics (FIGO IIIc stage. In the region of gene BRCA1, LOH was detected in 5/13 (38.5% tumors. Four of them had histological gradus G2, and one had gradus G3, while by the (FIGO classification one was with stage Ib, one was with stage IIIb, while the three were with stage IIIc. LOH in both of the analyzed regions was detected in one tumor (7.7%, with histological gradus G3 and the FIGO IIIc stage. Conclusion. The frequency of LOH in epthelial ovarian carcinomas was 30.7% and 38.5% for p53 and BRCA1 gene regions, respectively. Most of tumors with LOH had histological gradus G2 or G3, and the clinical FIGO stage IIIc, suggesting the

  18. Caffeine mediates sustained inactivation of breast cancer-associated myofibroblasts via up-regulation of tumor suppressor genes.

    Directory of Open Access Journals (Sweden)

    Mysoon M Al-Ansari

    Full Text Available BACKGROUND: Active cancer-associated fibroblasts (CAFs or myofibroblasts play important roles not only in the development and progression of breast carcinomas, but also in their prognosis and treatment. Therefore, targeting these cells through suppressing their supportive procarcinogenic paracrine effects is mandatory for improving the current therapies that are mainly targeting tumor cells. To this end, we investigated the effect of the natural and pharmacologically safe molecule, caffeine, on CAF cells and their various procarcinogenic effects. METHODOLOGY/PRINCIPAL FINDINGS: We have shown here that caffeine up-regulates the tumor suppressor proteins p16, p21, p53 and Cav-1, and reduces the expression/secretion of various cytokines (IL-6, TGF-β, SDF-1 and MMP-2, and down-regulates α-SMA. Furthermore, caffeine suppressed the migratory/invasiveness abilities of CAF cells through PTEN-dependent Akt/Erk1/2 inactivation. Moreover, caffeine reduced the paracrine pro-invasion/-migration effects of CAF cells on breast cancer cells. These results indicate that caffeine can inactivate breast stromal myofibroblasts. This has been confirmed by showing that caffeine also suppresses the paracrine pro-angiogenic effect of CAF cells through down-regulating HIF-1αand its downstream effector VEGF-A. Interestingly, these effects were sustained in absence of caffeine. CONCLUSION/SIGNIFICANCE: The present findings provide a proof of principle that breast cancer myofibroblasts can be inactivated, and thereby caffeine may provide a safe and effective prevention against breast tumor growth/recurrence through inhibition of the procarcinogenic effects of active stromal fibroblasts.

  19. Caffeine Mediates Sustained Inactivation of Breast Cancer-Associated Myofibroblasts via Up-Regulation of Tumor Suppressor Genes

    Science.gov (United States)

    Al-Ansari, Mysoon M.; Aboussekhra, Abdelilah

    2014-01-01

    Background Active cancer-associated fibroblasts (CAFs) or myofibroblasts play important roles not only in the development and progression of breast carcinomas, but also in their prognosis and treatment. Therefore, targeting these cells through suppressing their supportive procarcinogenic paracrine effects is mandatory for improving the current therapies that are mainly targeting tumor cells. To this end, we investigated the effect of the natural and pharmacologically safe molecule, caffeine, on CAF cells and their various procarcinogenic effects. Methodology/Principal Findings We have shown here that caffeine up-regulates the tumor suppressor proteins p16, p21, p53 and Cav-1, and reduces the expression/secretion of various cytokines (IL-6, TGF-β, SDF-1 and MMP-2), and down-regulates α-SMA. Furthermore, caffeine suppressed the migratory/invasiveness abilities of CAF cells through PTEN-dependent Akt/Erk1/2 inactivation. Moreover, caffeine reduced the paracrine pro-invasion/−migration effects of CAF cells on breast cancer cells. These results indicate that caffeine can inactivate breast stromal myofibroblasts. This has been confirmed by showing that caffeine also suppresses the paracrine pro-angiogenic effect of CAF cells through down-regulating HIF-1αand its downstream effector VEGF-A. Interestingly, these effects were sustained in absence of caffeine. Conclusion/Significance The present findings provide a proof of principle that breast cancer myofibroblasts c