Mutations blocking side chain assembly, polymerization, or transport of a Wzy-dependent Streptococcus pneumoniae capsule are lethal in the absence of suppressor mutations and can affect polymer transfer to the cell wall.

Science.gov (United States)

Xayarath, Bobbi; Yother, Janet

2007-05-01

Extracellular polysaccharides of many bacteria are synthesized by the Wzy polymerase-dependent mechanism, where long-chain polymers are assembled from undecaprenyl-phosphate-linked repeat units on the outer face of the cytoplasmic membrane. In gram-positive bacteria, Wzy-dependent capsules remain largely cell associated via membrane and peptidoglycan linkages. Like many Wzy-dependent capsules, the Streptococcus pneumoniae serotype 2 capsule is branched. In this study, we found that deletions of cps2K, cps2J, or cps2H, which encode a UDP-glucose dehydrogenase necessary for side chain synthesis, the putative Wzx transporter (flippase), and the putative Wzy polymerase, respectively, were obtained only in the presence of suppressor mutations. Most of the suppressor mutations were in cps2E, which encodes the initiating glycosyltransferase for capsule synthesis. The cps2K mutants containing the suppressor mutations produced low levels of high-molecular-weight polymer that was detected only in membrane fractions. cps2K-repaired mutants exhibited only modest increases in capsule production due to the effect of the secondary mutation, but capsule was detectable in both membrane and cell wall fractions. Lethality of the cps2K, cps2J, and cps2H mutations was likely due to sequestration of undecaprenyl-phosphate in the capsule pathway and either preclusion of its turnover for utilization in essential pathways or destabilization of the membrane due to an accumulation of lipid-linked intermediates. The results demonstrate that proper polymer assembly requires not only a functional transporter and polymerase but also complete repeat units. A central role for the initiating glycosyltransferase in controlling capsule synthesis is also suggested.

Germ-line mutations of the p53 tumor suppressor gene in patients with high risk for cancer inactivate the p53 protein.

OpenAIRE

Frebourg, T; Kassel, J; Lam, K T; Gryka, M A; Barbier, N; Andersen, T I; Børresen, A L; Friend, S H

1992-01-01

Germ-line mutations in the p53 tumor suppressor gene have been observed in patients with Li-Fraumeni syndrome, brain tumors, second malignancies, and breast cancers. It is unclear whether all of these mutations have inactivated p53 and thereby provide an increased risk for cancer. Therefore, it is necessary to establish the biological significance of these germ-line mutations by the functional and structural analysis of the resulting mutant p53 proteins. We analyzed the ability of seven germ-...

Heterozygous Germline Mutations in the CBL Tumor-Suppressor Gene Cause a Noonan Syndrome-like Phenotype

Science.gov (United States)

Martinelli, Simone; De Luca, Alessandro; Stellacci, Emilia; Rossi, Cesare; Checquolo, Saula; Lepri, Francesca; Caputo, Viviana; Silvano, Marianna; Buscherini, Francesco; Consoli, Federica; Ferrara, Grazia; Digilio, Maria C.; Cavaliere, Maria L.; van Hagen, Johanna M.; Zampino, Giuseppe; van der Burgt, Ineke; Ferrero, Giovanni B.; Mazzanti, Laura; Screpanti, Isabella; Yntema, Helger G.; Nillesen, Willy M.; Savarirayan, Ravi; Zenker, Martin; Dallapiccola, Bruno; Gelb, Bruce D.; Tartaglia, Marco

2010-01-01

RAS signaling plays a key role in controlling appropriate cell responses to extracellular stimuli and participates in early and late developmental processes. Although enhanced flow through this pathway has been established as a major contributor to oncogenesis, recent discoveries have revealed that aberrant RAS activation causes a group of clinically related developmental disorders characterized by facial dysmorphism, a wide spectrum of cardiac disease, reduced growth, variable cognitive deficits, ectodermal and musculoskeletal anomalies, and increased risk for certain malignancies. Here, we report that heterozygous germline mutations in CBL, a tumor-suppressor gene that is mutated in myeloid malignancies and encodes a multivalent adaptor protein with E3 ubiquitin ligase activity, can underlie a phenotype with clinical features fitting or partially overlapping Noonan syndrome (NS), the most common condition of this disease family. Independent CBL mutations were identified in two sporadic cases and two families from among 365 unrelated subjects who had NS or suggestive features and were negative for mutations in previously identified disease genes. Phenotypic heterogeneity and variable expressivity were documented. Mutations were missense changes altering evolutionarily conserved residues located in the RING finger domain or the linker connecting this domain to the N-terminal tyrosine kinase binding domain, a known mutational hot spot in myeloid malignancies. Mutations were shown to affect CBL-mediated receptor ubiquitylation and dysregulate signal flow through RAS. These findings document that germline mutations in CBL alter development to cause a clinically variable condition that resembles NS and that possibly predisposes to malignancies. PMID:20619386

RET is a potential tumor suppressor gene in colorectal cancer

Science.gov (United States)

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

NF2 tumor suppressor gene: a comprehensive and efficient detection of somatic mutations by denaturing HPLC and microarray-CGH.

Science.gov (United States)

Szijan, Irene; Rochefort, Daniel; Bruder, Carl; Surace, Ezequiel; Machiavelli, Gloria; Dalamon, Viviana; Cotignola, Javier; Ferreiro, Veronica; Campero, Alvaro; Basso, Armando; Dumanski, Jan P; Rouleau, Guy A

2003-01-01

The NF2 tumor suppressor gene, located in chromosome 22q12, is involved in the development of multiple tumors of the nervous system, either associated with neurofibromatosis 2 or sporadic ones, mainly schwannomas and meningiomas. In order to evaluate the role of the NF2 gene in sporadic central nervous system (CNS) tumors, we analyzed NF2 mutations in 26 specimens: 14 meningiomas, 4 schwannomas, 4 metastases, and 4 other histopathological types of neoplasms. Denaturing high performance liquid chromatography (denaturing HPLC) and comparative genomic hybridization on a DNA microarray (microarray- CGH) were used as scanning methods for small mutations and gross rearrangements respectively. Small mutations were identified in six out of seventeen meningiomas and schwannomas, one mutation was novel. Large deletions were detected in six meningiomas. All mutations were predicted to result in truncated protein or in the absence of a large protein domain. No NF2 mutations were found in other histopathological types of CNS tumors. These results provide additional evidence that mutations in the NF2 gene play an important role in the development of sporadic meningiomas and schwannomas. Denaturing HPLC analysis of small mutations and microarray-CGH of large deletions are complementary, fast, and efficient methods for the detection of mutations in tumor tissues.

Clinical and pathological associations with p53 tumour-suppressor gene mutations and expression of p21WAF1/Cip1 in colorectal carcinoma

NARCIS (Netherlands)

Slebos, R. J.; Baas, I. O.; Clement, M.; Polak, M.; Mulder, J. W.; van den Berg, F. M.; Hamilton, S. R.; Offerhaus, G. J.

1996-01-01

Inactivation of the p53 tumour-suppressor gene is common in a wide variety of human neoplasms. In the majority of cases, single point mutations in the protein-encoding sequence of p53 lead to positive immunohistochemistry (IHC) for the p53 protein, and are accompanied by loss of the wild-type

The Ras effector RASSF2 is a novel tumor-suppressor gene in human colorectal cancer.

Science.gov (United States)

Akino, Kimishige; Toyota, Minoru; Suzuki, Hiromu; Mita, Hiroaki; Sasaki, Yasushi; Ohe-Toyota, Mutsumi; Issa, Jean-Pierre J; Hinoda, Yuji; Imai, Kohzoh; Tokino, Takashi

2005-07-01

Activation of Ras signaling is a hallmark of colorectal cancer (CRC), but the roles of negative regulators of Ras are not fully understood. Our aim was to address that question by surveying genetic and epigenetic alterations of Ras-Ras effector genes in CRC cells. The expression and methylation status of 6 RASSF family genes were examined using RT-PCR and bisulfite PCR in CRC cell lines and in primary CRCs and colorectal adenomas. Colony formation assays and flow cytometry were used to assess the tumor suppressor activities of RASSF1 and RASSF2. Immunofluorescence microscopy was used to determine the effect of altered RASSF2 expression on cell morphology. Mutations of K- ras , BRAF, and p53 were identified using single-strand conformation analysis and direct sequencing. Aberrant methylation and histone deacetylation of RASSF2 was associated with the gene's silencing in CRC. The activities of RASSF2, which were distinct from those of RASSF1, included induction of morphologic changes and apoptosis; moreover, its ability to prevent cell transformation suggests that RASSF2 acts as a tumor suppressor in CRC. Primary CRCs that showed K- ras /BRAF mutations also frequently showed RASSF2 methylation, and inactivation of RASSF2 enhanced K- ras -induced oncogenic transformation. RASSF2 methylation was also frequently identified in colorectal adenomas. RASSF2 is a novel tumor suppressor gene that regulates Ras signaling and plays a pivotal role in the early stages of colorectal tumorigenesis.

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.

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

OpenAIRE

Minervini, Giovanni; Mazzotta, Gabriella M.; Masiero, Alessandro; Sartori, Elena; Corr?, 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 t...

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

Directory of Open Access Journals (Sweden)

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.

F-box-like domain in the polerovirus protein P0 is required for silencing suppressor function

Science.gov (United States)

Pazhouhandeh, Maghsoud; Dieterle, Monika; Marrocco, Katia; Lechner, Esther; Berry, Bassam; Brault, Véronique; Hemmer, Odile; Kretsch, Thomas; Richards, Kenneth E.; Genschik, Pascal; Ziegler-Graff, Véronique

2006-01-01

Plants employ small RNA-mediated posttranscriptional gene silencing as a virus defense mechanism. In response, plant viruses encode proteins that can suppress RNA silencing, but the mode of action of most such proteins is poorly understood. Here, we show that the silencing suppressor protein P0 of two Arabidopsis-infecting poleroviruses interacts by means of a conserved minimal F-box motif with Arabidopsis thaliana orthologs of S-phase kinase-related protein 1 (SKP1), a component of the SCF family of ubiquitin E3 ligases. Point mutations in the F-box-like motif abolished the P0–SKP1 ortholog interaction, diminished virus pathogenicity, and inhibited the silencing suppressor activity of P0. Knockdown of expression of a SKP1 ortholog in Nicotiana benthamiana rendered the plants resistant to polerovirus infection. Together, the results support a model in which P0 acts as an F-box protein that targets an essential component of the host posttranscriptional gene silencing machinery. PMID:16446454

Molecular biology III - Oncogenes and tumor suppressor genes

International Nuclear Information System (INIS)

Giaccia, Amato J.

1996-01-01

Purpose: The purpose of this course is to introduce to radiation oncologists the basic concepts of tumorigenesis, building on the information that will be presented in the first and second part of this series of lectures. Objective: Our objective is to increase the current understanding of radiation oncologists with the process of tumorigenesis, especially focusing on genes that are altered in many tumor types that are potential candidates for novel molecular strategies. As strategies to treat cancer of cancer are becoming more sophisticated, it will be important for both the practitioner and academician to develop a basic understanding of the function of cancer 'genes'. This will be the third in a series of refresher courses that are meant to address recent advances in Cancer Biology in a way that both clinicians without previous knowledge of molecular biology or experienced researchers will find interesting. The lecture will begin with a basic overview of tumorigenesis; methods of detecting chromosome/DNA alterations, approaches used to isolate oncogenes and tumor suppressor genes, and their role in cell killing by apoptosis. Special attention will be given to oncogenes and tumor suppressor genes that are modulated by ionizing radiation and the tumor microenvironment. We will relate the biology of oncogenes and tumor suppressor genes to basic aspects of radiation biology that would be important in clinical practice. Finally, we will review recent studies on the prognostic significance of p53 mutations and apoptosis in tumor specimens. The main point of this lecture is to relate both researcher and clinician what are the therapeutic ramifications of oncogene and tumor suppressor gene mutations found in human neoptasia

Suppressor Analysis of the Fusogenic Lambda Spanins.

Science.gov (United States)

Cahill, Jesse; Rajaure, Manoj; Holt, Ashley; Moreland, Russell; O'Leary, Chandler; Kulkarni, Aneesha; Sloan, Jordan; Young, Ry

2017-07-15

The final step of lysis in phage λ infections of Escherichia coli is mediated by the spanins Rz and Rz1. These proteins form a complex that bridges the cell envelope and that has been proposed to cause fusion of the inner and outer membranes. Accordingly, mutations that block spanin function are found within coiled-coil domains and the proline-rich region, motifs essential in other fusion systems. To gain insight into spanin function, pseudorevertant alleles that restored plaque formation for lysis-defective mutants of Rz and Rz1 were selected. Most second-site suppressors clustered within a coiled-coil domain of Rz near the outer leaflet of the cytoplasmic membrane and were not allele specific. Suppressors largely encoded polar insertions within the hydrophobic core of the coiled-coil interface. Such suppressor changes resulted in decreased proteolytic stability of the Rz double mutants in vivo Unlike the wild type, in which lysis occurs while the cells retain a rod shape, revertant alleles with second-site suppressor mutations supported lysis events that were preceded by spherical cell formation. This suggests that destabilization of the membrane-proximal coiled coil restores function for defective spanin alleles by increasing the conformational freedom of the complex at the cost of its normal, all-or-nothing functionality. IMPORTANCE Caudovirales encode cell envelope-spanning proteins called spanins, which are thought to fuse the inner and outer membranes during phage lysis. Recent genetic analysis identified the functional domains of the lambda spanins, which are similar to class I viral fusion proteins. While the pre- and postfusion structures of model fusion systems have been well characterized, the intermediate structure(s) formed during the fusion reaction remains elusive. Genetic analysis would be expected to identify functional connections between intermediates. Since most membrane fusion systems are not genetically tractable, only few such

Mutational myriad of tumor suppressor p53 in Filipino breast cancer: results and perspectives in molecular pathology and epidemiology

Energy Technology Data Exchange (ETDEWEB)

Deocaris, Custer C

2000-04-01

The p53 tumor suppressor is by far the most widely mutated gene in human cancers. p53 encodes a 53-kDa phosphoprotein, transcription-activator whose targets include genes and gene products that orchestrate genomic stability, cellular response to DNA damage, cell cycle progression apoptosis and aging (senescence). Analysis of the p53 gene profile has previously resulted in identifying several cancer-causative factors in the human setting, as well as, in creating a unique molecular profile of a tumor useful in the design of tailored-therapies for individual cancer patients. Our results in screening for p53 abnormalities in 140 Filipino patients with primary breast lesions confined from 1997-1998 in 5 major hospitals in Manila reveal that p53 plays an important role in the development and progression of breast cancer in at least 48% of all cases. Two methods of p53 analysis are employed, enzyme-linked immunosorbent assay (ELISA) and polymerase chain reaction-temporal temperature gradient electrophoresis (PCR-TTGE). Inter-comparisons of method exhibit 63.3% concordance in 21 fresh breast carcinoma samples, with ELISA demonstrating 14% false-positives and 10% false-negatives. Only mutations in exon 7 (p=0.063) in the tumor samples how significant correlation with abnormal cellular elevation of p53. PCR-TTGE screening in a large series of 140 patients show that most genetic lesions are localized in exons 5 (41% of the total cases) and 6 (27% of the total cases). No mutations are, however, detected in the transactivation (exons 2-4) and oligomerization (exons 10-11) domains. Invasive carcinomas (stages II and III) are characterized with more frequent and diverse genetic alterations compared with benign tumors, most significantly at exon 5B (p=0.066) and at independently multiple sites (p=0.066). Earlier-onset cases (age of diagnosis < 50 yrs), known to be more clinico-pathologically aggressive, are diagnosed harboring more frequent p53 mutations centered at exon 7 (p=0

Mutational myriad of tumor suppressor p53 in Filipino breast cancer: results and perspectives in molecular pathology and epidemiology

International Nuclear Information System (INIS)

Deocaris, Custer C.

2000-04-01

The p53 tumor suppressor is by far the most widely mutated gene in human cancers. p53 encodes a 53-kDa phosphoprotein, transcription-activator whose targets include genes and gene products that orchestrate genomic stability, cellular response to DNA damage, cell cycle progression apoptosis and aging (senescence). Analysis of the p53 gene profile has previously resulted in identifying several cancer-causative factors in the human setting, as well as, in creating a unique molecular profile of a tumor useful in the design of tailored-therapies for individual cancer patients. Our results in screening for p53 abnormalities in 140 Filipino patients with primary breast lesions confined from 1997-1998 in 5 major hospitals in Manila reveal that p53 plays an important role in the development and progression of breast cancer in at least 48% of all cases. Two methods of p53 analysis are employed, enzyme-linked immunosorbent assay (ELISA) and polymerase chain reaction-temporal temperature gradient electrophoresis (PCR-TTGE). Inter-comparisons of method exhibit 63.3% concordance in 21 fresh breast carcinoma samples, with ELISA demonstrating 14% false-positives and 10% false-negatives. Only mutations in exon 7 (p=0.063) in the tumor samples how significant correlation with abnormal cellular elevation of p53. PCR-TTGE screening in a large series of 140 patients show that most genetic lesions are localized in exons 5 (41% of the total cases) and 6 (27% of the total cases). No mutations are, however, detected in the transactivation (exons 2-4) and oligomerization (exons 10-11) domains. Invasive carcinomas (stages II and III) are characterized with more frequent and diverse genetic alterations compared with benign tumors, most significantly at exon 5B (p=0.066) and at independently multiple sites (p=0.066). Earlier-onset cases (age of diagnosis < 50 yrs), known to be more clinico-pathologically aggressive, are diagnosed harboring more frequent p53 mutations centered at exon 7 (p=0

Overexpression of the p53 tumor suppressor gene product in primary lung adenocarcinomas is associated with cigarette smoking

NARCIS (Netherlands)

Westra, W. H.; Offerhaus, G. J.; Goodman, S. N.; Slebos, R. J.; Polak, M.; Baas, I. O.; Rodenhuis, S.; Hruban, R. H.

1993-01-01

Mutations in the p53 tumor suppressor gene are frequently observed in primary lung adenocarcinomas, suggesting that these mutations are critical events in the malignant transformation of airway cells. These mutations are often associated with stabilization of the p53 gene product, resulting in the

Genome‐wide DNA methylation analysis identifies MEGF10 as a novel epigenetically repressed candidate tumor suppressor gene in neuroblastoma

Science.gov (United States)

Charlet, Jessica; Tomari, Ayumi; Dallosso, Anthony R.; Szemes, Marianna; Kaselova, Martina; Curry, Thomas J.; Almutairi, Bader; Etchevers, Heather C.; McConville, Carmel; Malik, Karim T. A.

2016-01-01

Neuroblastoma is a childhood cancer in which many children still have poor outcomes, emphasising the need to better understand its pathogenesis. Despite recent genome‐wide mutation analyses, many primary neuroblastomas do not contain recognizable driver mutations, implicating alternate molecular pathologies such as epigenetic alterations. To discover genes that become epigenetically deregulated during neuroblastoma tumorigenesis, we took the novel approach of comparing neuroblastomas to neural crest precursor cells, using genome‐wide DNA methylation analysis. We identified 93 genes that were significantly differentially methylated of which 26 (28%) were hypermethylated and 67 (72%) were hypomethylated. Concentrating on hypermethylated genes to identify candidate tumor suppressor loci, we found the cell engulfment and adhesion factor gene MEGF10 to be epigenetically repressed by DNA hypermethylation or by H3K27/K9 methylation in neuroblastoma cell lines. MEGF10 showed significantly down‐regulated expression in neuroblastoma tumor samples; furthermore patients with the lowest‐expressing tumors had reduced relapse‐free survival. Our functional studies showed that knock‐down of MEGF10 expression in neuroblastoma cell lines promoted cell growth, consistent with MEGF10 acting as a clinically relevant, epigenetically deregulated neuroblastoma tumor suppressor gene. © 2016 The Authors. Molecular Carcinogenesis Published by Wiley Periodicals, Inc. PMID:27862318

Tumor Suppressor Activity of the EphB2 Receptor in Prostate Cancer

National Research Council Canada - National Science Library

Pasquale, Elena B

2007-01-01

Mutations have been recently identified in the EphB2 receptor gene in prostate cancer suggesting that EphB2, a member of the large Eph receptor tyrosine kinase family, is a tumor suppressor in prostate cancer...

Tumor Suppressor Activity of the EphB2 Receptor in Prostate Cancer

National Research Council Canada - National Science Library

Pasquale, Elena B

2006-01-01

Mutations have been recently identified in the EphB2 receptor gene in prostate cancer suggesting that EphB2, a member of the large Eph receptor tyrosine kinase family, is a tumor suppressor in prostate cancer...

Tumor suppressors: enhancers or suppressors of regeneration?

Science.gov (United States)

Pomerantz, Jason H.; Blau, Helen M.

2013-01-01

Tumor suppressors are so named because cancers occur in their absence, but these genes also have important functions in development, metabolism and tissue homeostasis. Here, we discuss known and potential functions of tumor suppressor genes during tissue regeneration, focusing on the evolutionarily conserved tumor suppressors pRb1, p53, Pten and Hippo. We propose that their activity is essential for tissue regeneration. This is in contrast to suggestions that tumor suppression is a trade-off for regenerative capacity. We also hypothesize that certain aspects of tumor suppressor pathways inhibit regenerative processes in mammals, and that transient targeted modification of these pathways could be fruitfully exploited to enhance processes that are important to regenerative medicine. PMID:23715544

P18 tumor suppressor gene and progression of oligodendrogliomas to anaplasia.

Science.gov (United States)

He, J; Hoang-Xuan, K; Marie, Y; Leuraud, P; Mokhtari, K; Kujas, M; Delattre, J Y; Sanson, M

2000-09-26

P18INK4C is a good candidate to be the tumor suppressor gene involved in oligodendrogliomas on 1p32. Loss of heterozygosity on 1p, mutation(s), homozygous deletion(s), and expression of p18 in 30 oligodendroglial tumors were investigated. Loss of heterozygosity on 1p was found in 15 tumors. A p18 mutation was found at an recurrence of an anaplastic oligodendroglioma, but not in the primary, low-grade tumor. No homozygous deletions were found and p18 was expressed in all cases. These results show that p18 alteration is involved in tumor progression in a subset of oligodendrogliomas.

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.

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

International Nuclear Information System (INIS)

Mack, Hildegard I.D.; Munger, Karl

2013-01-01

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

Cowpea mosaic virus RNA-1 acts as an amplicon whose effects can be counteracted by a RNA-2-encoded suppressor of silencing

International Nuclear Information System (INIS)

Liu Li; Grainger, Jef; Canizares, M. Carmen; Angell, Susan M.; Lomonossoff, George P.

2004-01-01

Lines of Nicotiana benthamiana transgenic for full-length copies of both Cowpea mosaic virus (CPMV) genomic RNAs, either singly or together, have been produced. Plants transgenic for both RNAs developed symptoms characteristic of a CPMV infection. When plants transgenic for RNA-1 were agro-inoculated with RNA-2, no infection developed and the plants were also resistant to challenge with CPMV. By contrast, plants transgenic for RNA-2 became infected when agro-inoculated with RNA-1 and were fully susceptible to CPMV infection. The resistance of RNA-1 transgenic plants was shown to be related to the ability of RNA-1 to self-replicate and act as an amplicon. The ability of transgenically expressed RNA-2 to counteract the amplicon effect suggested that it encodes a suppressor of posttranscriptional gene silencing (PTGS). By examining the ability of portions of RNA-2 to reverse PTGS in N. benthamiana, we have identified the small (S) coat protein as the CPMV RNA-2-encoded suppressor of PTGS

Cox1 mutation abrogates need for Cox23 in cytochrome c oxidase biogenesis

Directory of Open Access Journals (Sweden)

Richard Dela Cruz

2016-06-01

Full Text Available Cox23 is a known conserved assembly factor for cytochrome c oxidase, although its role in cytochrome c oxidase (CcO biogenesis remains unresolved. To gain additional insights into its role, we isolated spontaneous suppressors of the respiratory growth defect in cox23∆ yeast cells. We recovered independent colonies that propagated on glycerol/lactate medium for cox23∆ cells at 37°C. We mapped these mutations to the mitochondrial genome and specifically to COX1 yielding an I101F substitution. The I101F Cox1 allele is a gain-of-function mutation enabling yeast to respire in the absence of Cox23. CcO subunit steady-state levels were restored with the I101F Cox1 suppressor mutation and oxygen consumption and CcO activity were likewise restored. Cells harboring the mitochondrial genome encoding I101F Cox1 were used to delete genes for other CcO assembly factors to test the specificity of the Cox1 mutation as a suppressor of cox23∆ cells. The Cox1 mutant allele fails to support respiratory growth in yeast lacking Cox17, Cox19, Coa1, Coa2, Cox14 or Shy1, demonstrating its specific suppressor activity for cox23∆ cells.

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.

Cell size checkpoint control by the retinoblastoma tumor suppressor pathway.

Science.gov (United States)

Fang, Su-Chiung; de los Reyes, Chris; Umen, James G

2006-10-13

Size control is essential for all proliferating cells, and is thought to be regulated by checkpoints that couple cell size to cell cycle progression. The aberrant cell-size phenotypes caused by mutations in the retinoblastoma (RB) tumor suppressor pathway are consistent with a role in size checkpoint control, but indirect effects on size caused by altered cell cycle kinetics are difficult to rule out. The multiple fission cell cycle of the unicellular alga Chlamydomonas reinhardtii uncouples growth from division, allowing direct assessment of the relationship between size phenotypes and checkpoint function. Mutations in the C. reinhardtii RB homolog encoded by MAT3 cause supernumerous cell divisions and small cells, suggesting a role for MAT3 in size control. We identified suppressors of an mat3 null allele that had recessive mutations in DP1 or dominant mutations in E2F1, loci encoding homologs of a heterodimeric transcription factor that is targeted by RB-related proteins. Significantly, we determined that the dp1 and e2f1 phenotypes were caused by defects in size checkpoint control and were not due to a lengthened cell cycle. Despite their cell division defects, mat3, dp1, and e2f1 mutants showed almost no changes in periodic transcription of genes induced during S phase and mitosis, many of which are conserved targets of the RB pathway. Conversely, we found that regulation of cell size was unaffected when S phase and mitotic transcription were inhibited. Our data provide direct evidence that the RB pathway mediates cell size checkpoint control and suggest that such control is not directly coupled to the magnitude of periodic cell cycle transcription.

Ring structure amino acids affect the suppressor activity of melon aphid-borne yellows virus P0 protein.

Science.gov (United States)

Han, Yan-Hong; Xiang, Hai-Ying; Wang, Qian; Li, Yuan-Yuan; Wu, Wen-Qi; Han, Cheng-Gui; Li, Da-Wei; Yu, Jia-Lin

2010-10-10

Melon aphid-borne yellows virus (MABYV) is a newly identified polerovirus occurring in China. Here, we demonstrate that the MABYV encoded P0 (P0(MA)) protein is a strong suppressor of post-transcriptional gene silencing (PTGS) with activity comparable to tobacco etch virus (TEV) HC-Pro. In addition we have shown that the LP F-box motif present at the N-terminus of P0(MA) is required for suppressor activity. Detailed mutational analyses on P0(MA) revealed that changing the conserved Trp 212 with non-ring structured amino acids altered silencing suppressor functions. Ala substitutions at positions 12 and 211 for Phe had no effect on P0 suppression-activity, whereas Arg and Glu substitutions had greatly decreased suppressor activity. Furthermore, substitutions targeting Phe at position 30 also resulted in reduced P0 suppression-activity. Altogether, these results suggest that ring structured Trp/Phe residues in P0 have important roles in suppressor activity. Copyright © 2010 Elsevier Inc. All rights reserved.

NLRX1 Acts as an Epithelial-Intrinsic Tumor Suppressor through the Modulation of TNF-Mediated Proliferation

Directory of Open Access Journals (Sweden)

Ivan Tattoli

2016-03-01

Full Text Available The mitochondrial Nod-like receptor protein NLRX1 protects against colorectal tumorigenesis through mechanisms that remain unclear. Using mice with an intestinal epithelial cells (IEC-specific deletion of Nlrx1, we find that NLRX1 provides an IEC-intrinsic protection against colitis-associated carcinogenesis in the colon. These Nlrx1 mutant mice have increased expression of Tnf, Egf, and Tgfb1, three factors essential for wound healing, as well as increased epithelial proliferation during the epithelial regeneration phase following injury triggered by dextran sodium sulfate. In primary intestinal organoids lacking Nlrx1, stimulation with TNF resulted in exacerbated proliferation and expression of the intestinal stem cell markers Olfm4 and Myb. This hyper-proliferation response was associated with increased activation of Akt and NF-κB pathways in response to TNF stimulation. Together, these results identify NLRX1 as a suppressor of colonic tumorigenesis that acts by controlling epithelial proliferation in the intestine during the regeneration phase following mucosal injury.

Structural investigation of nucleophosmin interaction with the tumor suppressor Fbw7γ.

Science.gov (United States)

Di Matteo, A; Franceschini, M; Paiardini, A; Grottesi, A; Chiarella, S; Rocchio, S; Di Natale, C; Marasco, D; Vitagliano, L; Travaglini-Allocatelli, C; Federici, L

2017-09-18

Nucleophosmin (NPM1) is a multifunctional nucleolar protein implicated in ribogenesis, centrosome duplication, cell cycle control, regulation of DNA repair and apoptotic response to stress stimuli. The majority of these functions are played through the interactions with a variety of protein partners. NPM1 is frequently overexpressed in solid tumors of different histological origin. Furthermore NPM1 is the most frequently mutated protein in acute myeloid leukemia (AML) patients. Mutations map to the C-terminal domain and lead to the aberrant and stable localization of the protein in the cytoplasm of leukemic blasts. Among NPM1 protein partners, a pivotal role is played by the tumor suppressor Fbw7γ, an E3-ubiquitin ligase that degrades oncoproteins like c-MYC, cyclin E, Notch and c-jun. In AML with NPM1 mutations, Fbw7γ is degraded following its abnormal cytosolic delocalization by mutated NPM1. This mechanism also applies to other tumor suppressors and it has been suggested that it may play a key role in leukemogenesis. Here we analyse the interaction between NPM1 and Fbw7γ, by identifying the protein surfaces implicated in recognition and key aminoacids involved. Based on the results of computational methods, we propose a structural model for the interaction, which is substantiated by experimental findings on several site-directed mutants. We also extend the analysis to two other NPM1 partners (HIV Tat and CENP-W) and conclude that NPM1 uses the same molecular surface as a platform for recognizing different protein partners. We suggest that this region of NPM1 may be targeted for cancer treatment.

Suppressor cells in transplantation tolerance II. Maturation of suppressor cells in the bone marrow chimera

International Nuclear Information System (INIS)

Tutschka, P.J.; Ki, P.F.; Beschorner, W.E.; Hess, A.D.; Santos, G.W.

1981-01-01

Histoincompatible bone marrow allografts were established in lethally irradiated rats. At various times after transplantation, the spleen cells were harvested, subjected to mixed lymphocyte cultures, and assayed for suppressor cells in vitro and in vivo by adoptive transfer studies. Alloantigen-nonspecific suppressor cells appeared in the chimera at 40 days after grafting, coinciding with the resolution of graft-versus-host disease (GVHD). At 250 days the nonspecific suppressor cells were replaced by suppressor cells specifically suppressing donor-versus-host alloantigen responses. At 720 days suppressor cells could no longer be identified by in vitro methods but were identified by in vivo adoptive transfer of transplantation tolerance. After injection of host-type antigen into chimeras, the suppressor cells could be again demonstrated by in vitro methods

Suppressor cells in transplantation tolerance. II. maturation of suppressor cells in the bone marrow chimera

International Nuclear Information System (INIS)

Tutschka, P.J.; Ki, P.F.; Beschorner, W.E.; Hess, A.D.; Santos, G.W.

1981-01-01

Histoincompatible bone marrow allografts were established in lethally irradiated rats. At various times after transplantation, the spleen cells were harvested, subjected to mixed lymphocyte cultures, and assayed for suppressor cells in vitro and in vivo by adoptive transfer studies. Alloantigen-nonspecific suppressor cells appeared in the chimera at 40 days after grafting, coinciding with the resolution of graft-versus-host disease (GVHD). At 250 days the nonspecific suppressor cells were replaced by suppressor cells specifically suppressing donor-versus-host alloantigen responses. At 720 days suppressor cells could no longer be identified by in vitro methods but were identified by in vivo adoptive transfer of transplantation tolerance. After injection of host-type antigen into chimeras, the suppressor cells could be again demonstrated by in vitro methods

Random mtDNA mutations modulate proliferation capacity in mouse embryonic fibroblasts

International Nuclear Information System (INIS)

Kukat, Alexandra; Edgar, Daniel; Bratic, Ivana; Maiti, Priyanka; Trifunovic, Aleksandra

2011-01-01

Highlights: → Increased mtDNA mutations in MEFs lead to high level of spontaneous immortalization. → This process is independent of endogenous ROS production. → Aerobic glycolysis significantly contributes to spontaneous immortalization of MEFs. -- Abstract: An increase in mtDNA mutation load leads to a loss of critical cells in different tissues thereby contributing to the physiological process of organismal ageing. Additionally, the accumulation of senescent cells that display changes in metabolic function might act in an active way to further disrupt the normal tissue function. We believe that this could be the important link missing in our understanding of the molecular mechanisms of premature ageing in the mtDNA mutator mice. We tested proliferation capacity of mtDNA mutator cells in vitro. When cultured in physiological levels of oxygen (3%) their proliferation capacity is somewhat lower than wild-type cells. Surprisingly, in conditions of increased oxidative stress (20% O 2 ) mtDNA mutator mouse embryonic fibroblasts exhibit continuous proliferation due to spontaneous immortalization, whereas the same conditions promote senescence in wild-type cells. We believe that an increase in aerobic glycolysis observed in mtDNA mutator mice is a major mechanism behind this process. We propose that glycolysis promotes proliferation and allows a fast turnover of metabolites, but also leads to energy crisis due to lower ATP production rate. This could lead to compromised replication and/or repair and therefore, in rare cases, might lead to mutations in tumor suppressor genes and spontaneous immortalization.

Loss of photoreversibility for UV mutation in E. coli using 405 nm or near-UV challenge

International Nuclear Information System (INIS)

Kristoff, S.; Bockrath, R.

1983-01-01

E. coli mutagenized with germicidal ultraviolet light (UV) were incubated to allow for development of mutation-fixation processes. Fixation was estimated from the effects on mutation frequency of photoreactivation challenge during the first 60 min post-UV. Two different light sources were used for photoreactivation, one providing effective light primarily at 405 nm and another providing a broad range of near-UV around 365 nm. Kinetics for the loss of photoreversibility (LOP) were determined. The times for completion of LOP in wild-type cells indicated one fixation process for back mutation and another for de novo or converted suppressor mutation regardless of the light source. Using 405-nm light for photoreactivation, the LOP kinetics for back mutation and de novo suppressor mutation in uvrA cells were similar. Hence, classical observations were confirmed here. Immediately post-UV all mutation frequencies were more sensitive to near-UV than 405-nm light. (orig./AJ)

Reduced rates of gene loss, gene silencing, and gene mutation in Dnmt1-deficient embryonic stem cells

NARCIS (Netherlands)

Chan, M.F.; van Amerongen, R.; Nijjar, T.; Cuppen, E.; Jones, P.A.; Laird, P.W.

2001-01-01

Tumor suppressor gene inactivation is a crucial event in oncogenesis. Gene inactivation mechanisms include events resulting in loss of heterozygosity (LOH), gene mutation, and transcriptional silencing. The contribution of each of these different pathways varies among tumor suppressor genes and by

The effect of age at exposure on the inactivating mechanisms and relative contributions of key tumor suppressor genes in radiation-induced mouse T-cell lymphomas

Energy Technology Data Exchange (ETDEWEB)

Sunaoshi, Masaaki [Radiobiology for Children' s Health Program, Research Center for Radiation Protection, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555 (Japan); Department of Biological Sciences, College of Science, Ibaraki University, Bunkyo 2-1-1, Mito, Ibaraki 310-8512 (Japan); Amasaki, Yoshiko; Hirano-Sakairi, Shinobu; Blyth, Benjamin J. [Radiobiology for Children' s Health Program, Research Center for Radiation Protection, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555 (Japan); Morioka, Takamitsu [Radiobiology for Children' s Health Program, Research Center for Radiation Protection, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555 (Japan); Radiation Effect Accumulation and Prevention Project, Fukushima Project Headquarters, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555 (Japan); Kaminishi, Mutsumi [Radiobiology for Children' s Health Program, Research Center for Radiation Protection, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555 (Japan); Shang, Yi [Radiation Effect Accumulation and Prevention Project, Fukushima Project Headquarters, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555 (Japan); Nishimura, Mayumi; Shimada, Yoshiya [Radiobiology for Children' s Health Program, Research Center for Radiation Protection, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555 (Japan); Radiation Effect Accumulation and Prevention Project, Fukushima Project Headquarters, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555 (Japan); Tachibana, Akira [Department of Biological Sciences, College of Science, Ibaraki University, Bunkyo 2-1-1, Mito, Ibaraki 310-8512 (Japan); and others

2015-09-15

Highlights: • T-cell lymphoma incidence, latency and weight did not change with age at exposure. • Lymphomas had frequent loss of heterozygosity on chromosomes 4, 11 and 19. • These lesions targeted the Cdkn2a, Ikaros and Pten tumor suppressor genes. • Age at exposure may influence which tumor suppressor genes are lost in each tumor. • The mechanisms of tumor suppressor gene loss were different at each locus. - Abstract: Children are considered more sensitive to radiation-induced cancer than adults, yet any differences in genomic alterations associated with age-at-exposure and their underlying mechanisms remain unclear. We assessed genome-wide DNA copy number and mutation of key tumor suppressor genes in T-cell lymphomas arising after weekly irradiation of female B6C3F1 mice with 1.2 Gy X-rays for 4 consecutive weeks starting during infancy (1 week old), adolescence (4 weeks old) or as young adults (8 weeks old). Although T-cell lymphoma incidence was similar, loss of heterozygosity at Cdkn2a on chromosome 4 and at Ikaros on chromosome 11 was more frequent in the two older groups, while loss at the Pten locus on chromosome 19 was more frequent in the infant-irradiated group. Cdkn2a and Ikaros mutation/loss was a common feature of the young adult-irradiation group, with Ikaros frequently (50%) incurring multiple independent hits (including deletions and mutations) or suffering a single hit predicted to result in a dominant negative protein (such as those lacking exon 4, an isoform we have designated Ik12, which lacks two DNA binding zinc-finger domains). Conversely, Pten mutations were more frequent after early irradiation (60%) than after young adult-irradiation (30%). Homozygous Pten mutations occurred without DNA copy number change after irradiation starting in infancy, suggesting duplication of the mutated allele by chromosome mis-segregation or mitotic recombination. Our findings demonstrate that while deletions on chromosomes 4 and 11 affecting Cdkn2

Statistical method on nonrandom clustering with application to somatic mutations in cancer

Directory of Open Access Journals (Sweden)

Rejto Paul A

2010-01-01

Full Text Available Abstract Background Human cancer is caused by the accumulation of tumor-specific mutations in oncogenes and tumor suppressors that confer a selective growth advantage to cells. As a consequence of genomic instability and high levels of proliferation, many passenger mutations that do not contribute to the cancer phenotype arise alongside mutations that drive oncogenesis. While several approaches have been developed to separate driver mutations from passengers, few approaches can specifically identify activating driver mutations in oncogenes, which are more amenable for pharmacological intervention. Results We propose a new statistical method for detecting activating mutations in cancer by identifying nonrandom clusters of amino acid mutations in protein sequences. A probability model is derived using order statistics assuming that the location of amino acid mutations on a protein follows a uniform distribution. Our statistical measure is the differences between pair-wise order statistics, which is equivalent to the size of an amino acid mutation cluster, and the probabilities are derived from exact and approximate distributions of the statistical measure. Using data in the Catalog of Somatic Mutations in Cancer (COSMIC database, we have demonstrated that our method detects well-known clusters of activating mutations in KRAS, BRAF, PI3K, and β-catenin. The method can also identify new cancer targets as well as gain-of-function mutations in tumor suppressors. Conclusions Our proposed method is useful to discover activating driver mutations in cancer by identifying nonrandom clusters of somatic amino acid mutations in protein sequences.

Recurrent APC gene mutations in Polish FAP families

Directory of Open Access Journals (Sweden)

Pławski Andrzej

2007-12-01

Full Text Available Abstract The molecular diagnostics of genetically conditioned disorders is based on the identification of the mutations in the predisposing genes. Hereditary cancer disorders of the gastrointestinal tracts are caused by mutations of the tumour suppressor genes or the DNA repair genes. Occurrence of recurrent mutation allows improvement of molecular diagnostics. The mutation spectrum in the genes causing hereditary forms of colorectal cancers in the Polish population was previously described. In the present work an estimation of the frequency of the recurrent mutations of the APC gene was performed. Eight types of mutations occurred in 19.4% of our FAP families and these constitute 43% of all Polish diagnosed families.

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.

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.

Repair-resistant mutation in Neurospora

International Nuclear Information System (INIS)

Stadler, D.; Macleod, H.; Loo, M.

1987-01-01

Chronic UV treatment produces severalfold fewer mutations in Neurospora conidia than does the same total dose of acute UV. Experiments were designed to determine the conditions required for chronic UV mutagenesis. Measurement of the coincidence frequency for two independent mutations revealed the existence of a subset of cells which are mutable by chronic UV. Analysis of forward mutation at the mtr locus showed that the genetic alterations produced by chronic UV were virtually all point mutants, even though the assay system could detect alterations or deletions extending into neighboring genes. A significant fraction of the mutants produced by acute UV were multigenic deletions. The size of the dose-rate effect (acute UV mutation frequency divided by chronic UV mutation frequency) was compared for several different mutation assay systems. Forward mutations (recessive lethals and mtr) gave values ranging from four to nine. For events which were restricted to specific molecular sites (specific reversions and nonsense suppressor mutations), there was a wider range of dose-rate ratios. This suggests that chronic UV mutation may be restricted to certain molecular sequences or configurations

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.

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

International Nuclear Information System (INIS)

Zhang, Heyu; Nan, Xu; Li, Xuefen; Chen, Yan; Zhang, Jianyun; Sun, Lisha; Han, Wenlin; Li, Tiejun

2014-01-01

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

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.

Understanding the tumor suppressor PTEN in chronic alcoholism and hepatocellular carcinoma.

Science.gov (United States)

Shearn, Colin T; Petersen, Dennis R

2015-01-01

The tumor suppressor phosphatase and tensin homolog deleted on chromosome 10 (PTEN) is a phosphatidylinositol (PtdIns) phosphatase that regulates Akt activation via PtdIns 3 kinase. Changes in PTEN expression and/or activity have been identified in a variety of chronic hepatocellular disorders including obesity, NAFLD, NASH, and alcoholism. In cancer biology, PTEN is frequently mutated or deleted in a wide variety of tumors. Mutations, decreased promoter activity, and decreased expression in PTEN are frequently identified in patients with hepatocellular carcinoma. While the majority of research on PTEN concerns obesity and NASH, PTEN clearly has a role in hepatic insulin sensitivity and in the development of steatosis during chronic alcoholism. Yet, in chronic alcoholics and HCC, very little is known concerning PTEN mutation/deletion or low PTEN expression. This review is focused on an overview of the current knowledge on molecular mechanisms of dysregulation of PTEN expression/activity in the liver and their relationship to development of ethanol-induced hepatocellular damage and cancer.

Tumor suppressor gene mutation in a patient with a history of hyperparathyroidism-jaw tumor syndrome and healed generalized osteitis fibrosa cystica: a case report and genetic pathophysiology review.

Science.gov (United States)

Parfitt, Joshua; Harris, Malcolm; Wright, John M; Kalamchi, Sabah

2015-01-01

Hyperparathyroidism-jaw tumor (HPT-JT) was first observed by Jackson in 1958 in a family who exhibited hyperparathyroidism and recurrent pancreatitis. The author noticed the presence of jaw tumors in the affected family and reported them as fibrous dysplasia. However, it was not until 1990 that a familial variety of hyperparathyroidism with fibro-osseous jaw tumors was recognized as HPT-JT syndrome and reported as a clinically and genetically distinct syndrome. Hyperparathyroidism generally arises from glandular hyperplasia or parathyroid adenomas, with only about 1% of cases resulting from parathyroid carcinoma. However, parathyroid carcinoma develops in about 15% of HPT-JT patients. The true incidence of HPT-JT is unknown, although the prevalence of about 100 published cases suggests its rarity. Twenty percent of HPT-JT cases have renal hamartomas or tumors, and female patients with HPT-JT have been reported to have carcinoma of the uterus. This syndrome appears to arise from a variety of mutations that deactivate the tumor suppressor gene CDC73 (also known as HRPT2) and its production of the tumor suppressor protein parafibromin. Functional parafibromin has 531 amino acids, and mutations result in a short nonfunctional protein. CDC73 disorders exhibit dominant germline gene behavior, with varying degrees of penetration. In most cases an affected person has 1 parent with the condition, which raises the need for family investigation and genetic counseling. We report a case of HPT-JT syndrome in a male patient who presented to the local community hospital 6 years previously with a history of back pain. Investigations showed elevated serum parathyroid hormone and calcium levels, and a technetium 99m sestamibi parathyroid scan showed increased activity at the site of the lower left gland that proved to be a substernal parathyroid carcinoma. The patient's parathyroid hormone level dropped from 126 to 97 pg/mL at 5 minutes and was 65 pg/mL at 10 minutes after excision

Mutations in TP53 tumor suppressor gene in wood dust-related sinonasal cancer

DEFF Research Database (Denmark)

Holmila, Reetta; Bornholdt, Jette; Heikkilä, Pirjo

2010-01-01

The causal role of work-related exposure to wood dust in the development of sinonasal cancer has long been established by numerous epidemiologic studies. To study molecular changes in these tumors, we analyzed TP53 gene mutations in 358 sinonasal cancer cases with or without occupational exposure...... affected the ORs only slightly. Smoking did not influence the occurrence of TP53 mutation; however, it was associated with multiple mutations (p = 0.03). As far as we are aware, this is the first study to demonstrate a high prevalence of TP53 mutation-positive cases in a large collection of sinonasal...... cancers with data on occupational exposure. Our results indicate that mutational mechanisms, in particular TP53 mutations, are associated with work-related exposure to wood dust in sinonasal cancer....

Sun exposure causes somatic second-hit mutations and angiofibroma development in tuberous sclerosis complex

Science.gov (United States)

Tyburczy, Magdalena E.; Wang, Ji-an; Li, Shaowei; Thangapazham, Rajesh; Chekaluk, Yvonne; Moss, Joel; Kwiatkowski, David J.; Darling, Thomas N.

2014-01-01

Tuberous sclerosis complex (TSC) is characterized by the formation of tumors in multiple organs and is caused by germline mutation in one of two tumor suppressor genes, TSC1 and TSC2. As for other tumor suppressor gene syndromes, the mechanism of somatic second-hit events in TSC tumors is unknown. We grew fibroblast-like cells from 29 TSC skin tumors from 22 TSC subjects and identified germline and second-hit mutations in TSC1/TSC2 using next-generation sequencing. Eighteen of 22 (82%) subjects had a mutation identified, and 8 of the 18 (44%) subjects were mosaic with mutant allele frequencies of 0 to 19% in normal tissue DNA. Multiple tumors were available from four patients, and in each case, second-hit mutations in TSC2 were distinct indicating they arose independently. Most remarkably, 7 (50%) of the 14 somatic point mutations were CC>TT ultraviolet ‘signature’ mutations, never seen as a TSC germline mutation. These occurred exclusively in facial angiofibroma tumors from sun-exposed sites. These results implicate UV-induced DNA damage as a cause of second-hit mutations and development of TSC facial angiofibromas and suggest that measures to limit UV exposure in TSC children and adults should reduce the frequency and severity of these lesions. PMID:24271014

DA-Raf, a dominant-negative antagonist of the Ras-ERK pathway, is a putative tumor suppressor.

Science.gov (United States)

Kanno, Emiri; Kawasaki, Osamu; Takahashi, Kazuya; Takano, Kazunori; Endo, Takeshi

2018-01-01

Activating mutations of RAS genes, particularly KRAS, are detected with high frequency in human tumors. Mutated Ras proteins constitutively activate the ERK pathway (Raf-MEK-ERK phosphorylation cascade), leading to cellular transformation and tumorigenesis. DA-Raf1 (DA-Raf) is a splicing variant of A-Raf and contains the Ras-binding domain (RBD) but lacks the kinase domain. Accordingly, DA-Raf antagonizes the Ras-ERK pathway in a dominant-negative fashion and suppresses constitutively activated K-Ras-induced cellular transformation. Thus, we have addressed whether DA-Raf serves as a tumor suppressor of Ras-induced tumorigenesis. DA-Raf(R52Q), which is generated from a single nucleotide polymorphism (SNP) in the RBD, and DA-Raf(R52W), a mutant detected in a lung cancer, neither bound to active K-Ras nor interfered with the activation of the ERK pathway. They were incapable of suppressing activated K-Ras-induced cellular transformation and tumorigenesis in mice, in which K-Ras-transformed cells were transplanted. Furthermore, although DA-Raf was highly expressed in lung alveolar epithelial type 2 (AE2) cells, its expression was silenced in AE2-derived lung adenocarcinoma cell lines with oncogenic KRAS mutations. These results suggest that DA-Raf represents a tumor suppressor protein against Ras-induced tumorigenesis. Copyright © 2017 Elsevier Inc. All rights reserved.

Missense Mutations Allow a Sequence-Blind Mutant of SpoIIIE to Successfully Translocate Chromosomes during Sporulation.

Science.gov (United States)

Bose, Baundauna; Reed, Sydney E; Besprozvannaya, Marina; Burton, Briana M

2016-01-01

SpoIIIE directionally pumps DNA across membranes during Bacillus subtilis sporulation and vegetative growth. The sequence-reading domain (γ domain) is required for directional DNA transport, and its deletion severely impairs sporulation. We selected suppressors of the spoIIIEΔγ sporulation defect. Unexpectedly, many suppressors were intragenic missense mutants, and some restore sporulation to near-wild-type levels. The mutant proteins are likely not more abundant, faster at translocating DNA, or sequence-sensitive, and rescue does not involve the SpoIIIE homolog SftA. Some mutants behave differently when co-expressed with spoIIIEΔγ, consistent with the idea that some, but not all, variants may form mixed oligomers. In full-length spoIIIE, these mutations do not affect sporulation, and yet the corresponding residues are rarely found in other SpoIIIE/FtsK family members. The suppressors do not rescue chromosome translocation defects during vegetative growth, indicating that the role of the γ domain cannot be fully replaced by these mutations. We present two models consistent with our findings: that the suppressors commit to transport in one arbitrarily-determined direction or delay spore development. It is surprising that missense mutations somehow rescue loss of an entire domain with a complex function, and this raises new questions about the mechanism by which SpoIIIE pumps DNA and the roles SpoIIIE plays in vivo.

Missense Mutations Allow a Sequence-Blind Mutant of SpoIIIE to Successfully Translocate Chromosomes during Sporulation.

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Baundauna Bose

Full Text Available SpoIIIE directionally pumps DNA across membranes during Bacillus subtilis sporulation and vegetative growth. The sequence-reading domain (γ domain is required for directional DNA transport, and its deletion severely impairs sporulation. We selected suppressors of the spoIIIEΔγ sporulation defect. Unexpectedly, many suppressors were intragenic missense mutants, and some restore sporulation to near-wild-type levels. The mutant proteins are likely not more abundant, faster at translocating DNA, or sequence-sensitive, and rescue does not involve the SpoIIIE homolog SftA. Some mutants behave differently when co-expressed with spoIIIEΔγ, consistent with the idea that some, but not all, variants may form mixed oligomers. In full-length spoIIIE, these mutations do not affect sporulation, and yet the corresponding residues are rarely found in other SpoIIIE/FtsK family members. The suppressors do not rescue chromosome translocation defects during vegetative growth, indicating that the role of the γ domain cannot be fully replaced by these mutations. We present two models consistent with our findings: that the suppressors commit to transport in one arbitrarily-determined direction or delay spore development. It is surprising that missense mutations somehow rescue loss of an entire domain with a complex function, and this raises new questions about the mechanism by which SpoIIIE pumps DNA and the roles SpoIIIE plays in vivo.

Zebrafish mutants in the von Hippel-Lindau tumor suppressor display a hypoxic response and recapitulate key aspects of Chuvash polycythemia

NARCIS (Netherlands)

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

2009-01-01

We have generated 2 zebrafish lines carrying inactivating germline mutations in the von Hippel-Lindau (VHL) tumor suppressor gene ortholog vhl. Mutant embryos display a general systemic hypoxic response, including the up-regulation of hypoxia-induced genes by 1 day after fertilization and a severe

[Clinical significance of drug resistance-associated mutations in treatment of hepatitis C with direct-acting antiviral agents].

Science.gov (United States)

Li, Z; Chen, Z W; Ren, H; Hu, P

2017-03-20

Direct-acting antiviral agents (DAAs) achieve a high sustained virologic response rate in the treatment of chronic hepatitis C virus infection. However, drug resistance-associated mutations play an important role in treatment failure and have attracted more and more attention. This article elaborates on the clinical significance of drug resistance-associated mutations from the aspects of their definition, association with genotype, known drug resistance-associated mutations and their prevalence rates, the impact of drug resistance-associated mutations on treatment naive and treatment-experienced patients, and the role of clinical detection, in order to provide a reference for clinical regimens with DAAs and help to achieve higher sustained virologic response rates.

MicroRNA-148b is frequently down-regulated in gastric cancer and acts as a tumor suppressor by inhibiting cell proliferation

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Jiang Li

2011-01-01

Full Text Available Abstract Background MicroRNAs (miRNAs are involved in cancer development and progression, acting as tumor suppressors or oncogenes. Our previous studies have revealed that miR-148a and miR-152 are significantly down-regulated in gastrointestinal cancers. Interestingly, miR-148b has the same "seed sequences" as miR-148a and miR-152. Although aberrant expression of miR-148b has been observed in several types of cancer, its pathophysiologic role and relevance to tumorigenesis are still largely unknown. The purpose of this study was to elucidate the molecular mechanisms by which miR-148b acts as a tumor suppressor in gastric cancer. Results We showed significant down-regulation of miR-148b in 106 gastric cancer tissues and four gastric cancer cell lines, compared with their non-tumor counterparts by real-time RT-PCR. In situ hybridization of ten cases confirmed an overt decrease in the level of miR-148b in gastric cancer tissues. Moreover, the expression of miR-148b was demonstrated to be associated with tumor size (P = 0.027 by a Mann-Whitney U test. We also found that miR-148b could inhibit cell proliferation in vitro by MTT assay, growth curves and an anchorage-independent growth assay in MGC-803, SGC-7901, BGC-823 and AGS cells. An experiment in nude mice revealed that miR-148b could suppress tumorigenicity in vivo. Using a luciferase activity assay and western blot, CCKBR was identified as a target of miR-148b in cells. Moreover, an obvious inverse correlation was observed between the expression of CCKBR protein and miR-148b in 49 pairs of tissues (P = 0.002, Spearman's correlation. Conclusions These findings provide important evidence that miR-148b targets CCKBR and is significant in suppressing gastric cancer cell growth. Maybe miR-148b would become a potential biomarker and therapeutic target against gastric cancer.

Human microRNA oncogenes and tumor suppressors show significantly different biological patterns: from functions to targets.

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Dong Wang

Full Text Available MicroRNAs (miRNAs are small noncoding RNAs which play essential roles in many important biological processes. Therefore, their dysfunction is associated with a variety of human diseases, including cancer. Increasing evidence shows that miRNAs can act as oncogenes or tumor suppressors, and although there is great interest in research into these cancer-associated miRNAs, little is known about them. In this study, we performed a comprehensive analysis of putative human miRNA oncogenes and tumor suppressors. We found that miRNA oncogenes and tumor suppressors clearly show different patterns in function, evolutionary rate, expression, chromosome distribution, molecule size, free energy, transcription factors, and targets. For example, miRNA oncogenes are located mainly in the amplified regions in human cancers, whereas miRNA tumor suppressors are located mainly in the deleted regions. miRNA oncogenes tend to cleave target mRNAs more frequently than miRNA tumor suppressors. These results indicate that these two types of cancer-associated miRNAs play different roles in cancer formation and development. Moreover, the patterns identified here can discriminate novel miRNA oncogenes and tumor suppressors with a high degree of accuracy. This study represents the first large-scale bioinformatic analysis of human miRNA oncogenes and tumor suppressors. Our findings provide help for not only understanding of miRNAs in cancer but also for the specific identification of novel miRNAs as miRNA oncogenes and tumor suppressors. In addition, the data presented in this study will be valuable for the study of both miRNAs and cancer.

Paraganglioma and pheochromocytoma upon maternal transmission of SDHD mutations

NARCIS (Netherlands)

J.P. Bayley; R.A. Oldenburg (Rogier); J. Nuk (Jennifer); A.S. Hoekstra (Attje S.); C.A. van der Meer (Conny); E. Korpershoek (Esther); B. McGillivray (Barbara); E.P. Corssmit (Eleonora); W.N.M. Dinjens (Winand); R.R. de Krijger (Ronald); P. Devilee (Peter); J.C. Jansen (Jeroen); F.J. Hes (Frederik)

2014-01-01

textabstractThe SDHD gene encodes a subunit of the mitochondrial tricarboxylic acid cycle enzyme and tumor suppressor, succinate dehydrogenase. Mutations in this gene show a remarkable pattern of parent-of-origin related tumorigenesis, with almost all SDHD-related cases of head and neck

Tumor suppressor WWOX and p53 alterations and drug resistance in glioblastomas

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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.

Evolution of the HIV-1 nef gene in HLA-B*57 Positive Elite Suppressors

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Siliciano Robert F

2010-11-01

Full Text Available Abstract Elite controllers or suppressors (ES are HIV-1 infected patients who maintain viral loads of gag and nef in HLA-B*57 positive ES. We previously showed evolution in the gag gene of ES which surprisingly was mostly due to synonymous mutations rather than non-synonymous mutation in targeted CTL epitopes. This finding could be the result of structural constraints on Gag, and we therefore examined the less conserved nef gene. We found slow evolution of nef in plasma virus in some ES. This evolution is mostly due to synonymous mutations and occurs at a rate similar to that seen in the gag gene in the same patients. The results provide further evidence of ongoing viral replication in ES and suggest that the nef and gag genes in these patients respond similarly to selective pressure from the host.

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

International Nuclear Information System (INIS)

Carey, Jason PW; Asirvatham, Ananthi J; Galm, Oliver; Ghogomu, Tandeih A; Chaudhary, Jaideep

2009-01-01

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. 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. 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. 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 silenced tumor suppressors

Novel Mutations in Synaptic Transmission Genes Suppress Neuronal Hyperexcitation in Caenorhabditis elegans

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Katherine A. McCulloch

2017-07-01

Full Text Available Acetylcholine (ACh receptors (AChR regulate neural circuit activity in multiple contexts. In humans, mutations in ionotropic acetylcholine receptor (iAChR genes can cause neurological disorders, including myasthenia gravis and epilepsy. In Caenorhabditis elegans, iAChRs play multiple roles in the locomotor circuit. The cholinergic motor neurons express an ACR-2-containing pentameric AChR (ACR-2R comprised of ACR-2, ACR-3, ACR-12, UNC-38, and UNC-63 subunits. A gain-of-function mutation in the non-α subunit gene acr-2 [acr-2(gf] causes defective locomotion as well as spontaneous convulsions. Previous studies of genetic suppressors of acr-2(gf have provided insights into ACR-2R composition and assembly. Here, to further understand how the ACR-2R regulates neuronal activity, we expanded the suppressor screen for acr-2(gf-induced convulsions. The majority of these suppressor mutations affect genes that play critical roles in synaptic transmission, including two novel mutations in the vesicular ACh transporter unc-17. In addition, we identified a role for a conserved major facilitator superfamily domain (MFSD protein, mfsd-6, in regulating neural circuit activity. We further defined a role for the sphingosine (SPH kinase (Sphk sphk-1 in cholinergic neuron activity, independent of previously known signaling pathways. Overall, the genes identified in our study suggest that optimal modulation of synaptic activity is balanced by the differential activities of multiple pathways, and the novel alleles provide valuable reagents to further dissect neuronal mechanisms regulating the locomotor circuit.

Distinct pattern of p53 mutations in bladder cancer

DEFF Research Database (Denmark)

Spruck, C H; Rideout, W M; Olumi, A F

1993-01-01

A distinct mutational spectrum for the p53 tumor suppressor gene in bladder carcinomas was established in patients with known exposures to cigarette smoke. Single-strand conformational polymorphism analysis of exons 5 through 8 of the p53 gene showed inactivating mutations in 16 of 40 (40%) bladder...... tumors from smokers and 13 of 40 (33%) tumors from lifetime nonsmokers. Overall, 13 of the 50 (26%) total point mutations discovered in this and previous work were G:C-->C:G transversions, a relatively rare mutational type in human tumors. In six tumors, identical AGA (Arg)-->ACA (Thr) point mutations...... double mutations, four of which were tandem mutations on the same allele. No double mutations were found in tumors from nonsmoking patients. None of the mutations in smokers were G:C-->T:A transversions, which would be anticipated for exposure to the suspected cigarette smoke carcinogen 4-aminobiphenyl...

Pharmacological activation of tumor suppressor, wild-type p53 as a promising strategy to fight cancer

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Alicja Sznarkowska

2010-08-01

Full Text Available A powerful tumor suppressor – p53 protein is a transcription factor which plays a critical role in eliciting cellular responses to a variety of stress signals, including DNA damage, hypoxia and aberrant proliferative signals, such as oncogene activation. Since its discovery thirty one years ago, p53 has been connected to tumorigenesis as it accumulates in the transformed tumor cells. Cellular stress induces stabilization of p53 and promotes, depending on the stress level, cell cycle arrest or apoptosis in the irreversibly damaged cells. The p53 protein is found inactive in more than 50�0of human tumors either by enhanced proteasomal degradation or due to the inactivating point mutations in its gene. Numerous data indicate that low molecular weight compounds, identified by molecular modeling or in the functional, cell-based assays, efficiently activate non-mutated p53 in cancer cells which in consequence leads to their elimination due to p53-dependent apoptosis. In this work we describe the structure and cellular function of p53 as well as the latest discoveries on the compounds with high anti-tumor activities aiming at reactivation of the tumor suppressor function of p53.

Identification of the second mutation of BADH2 gene derived from rice mutant lines induced by gamma rays

International Nuclear Information System (INIS)

I Ishak

2016-01-01

The BADH2 gene acts as suppressor of 2-acetyl-1-pyrolline (2AP) biosynthesis in plants. 2AP is the volatile compound which provides fragrance in rice. Biosynthesis of 2AP occurs when BADH2 loses its function as suppressor gene. Aromatic rice cultivars naturally incur mutation of BADH2 gene at 8 bp. In this experiment, aromatic mutant rice lines derived from irradiation of Sintanur cultivar by gamma rays with dose of 100 Gy were studied in molecular level. These mutant lines were characterized at the M10 plantgeneration under the assumption that genetically these aromatic mutant rice lines were homozygotic. Several primers related to aroma in rice have been used for polymerase chain reaction (PCR) in a thermal cycler instrument. Gel electrophoreses were carried out using 1.5% agarose in TAE buffer. DNA fragments at 254 bp and 355 bp (base pair) were taken and amplified by primer for nucleotide sequencing of these fragments. Molecular identification and characterization after electrophoresis showed that the mutant line from AR1020 can be differentiated from AR.1080 at 254 bp. Nucleotide sequence data from of these DNA fragments showed that point mutations (deletions and substitutions) occurred at the BADH2 gene in exon 7; those are called second mutation and were caused by gamma rays effects. The Sintanur variety was used as check cultivar and its DNA sequence was compared to that of the AR.1020 mutant line. The results from both DNA sequences (from cv. Sintanur and AR.1020) derived from fragments at 254 bp show that point mutations occurred within exon 7 and earlier stop codon occurred in the AR.1020 mutant rice line. Further, the use of EA primer in PCR resulted in detection of deletion and substitution of nucleotides in the AR.1020 mutant line. (author)

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 prolife...... tumor cells. Furthermore, we show that a negative correlation between miR-339-5p and MDM2 expression exists in human cancer, implying that the interaction is important for cancer development.Oncogene advance online publication, 2 June 2014; doi:10.1038/onc.2014.130....

Mast cell-deficient Kit(W-sh) "Sash" mutant mice display aberrant myelopoiesis leading to the accumulation of splenocytes that act as myeloid-derived suppressor cells.

Science.gov (United States)

Michel, Anastasija; Schüler, Andrea; Friedrich, Pamela; Döner, Fatma; Bopp, Tobias; Radsak, Markus; Hoffmann, Markus; Relle, Manfred; Distler, Ute; Kuharev, Jörg; Tenzer, Stefan; Feyerabend, Thorsten B; Rodewald, Hans-Reimer; Schild, Hansjörg; Schmitt, Edgar; Becker, Marc; Stassen, Michael

2013-06-01

Mast cell-deficient Kit(W-sh) "sash" mice are widely used to investigate mast cell functions. However, mutations of c-Kit also affect additional cells of hematopoietic and nonimmune origin. In this study, we demonstrate that Kit(W-sh) causes aberrant extramedullary myelopoiesis characterized by the expansion of immature lineage-negative cells, common myeloid progenitors, and granulocyte/macrophage progenitors in the spleen. A consistent feature shared by these cell types is the reduced expression of c-Kit. Populations expressing intermediate and high levels of Ly6G, a component of the myeloid differentiation Ag Gr-1, are also highly expanded in the spleen of sash mice. These cells are able to suppress T cell responses in vitro and phenotypically and functionally resemble myeloid-derived suppressor cells (MDSC). MDSC typically accumulate in tumor-bearing hosts and are able to dampen immune responses. Consequently, transfer of MDSC from naive sash mice into line 1 alveolar cell carcinoma tumor-bearing wild-type littermates leads to enhanced tumor progression. However, although it can also be observed in sash mice, accelerated growth of transplanted line 1 alveolar cell carcinoma tumors is a mast cell-independent phenomenon. Thus, the Kit(W-sh) mutation broadly affects key steps in myelopoiesis that may have an impact on mast cell research.

Is the gene encoding Chibby implicated as a tumour suppressor in colorectal cancer ?

International Nuclear Information System (INIS)

Gad, Sophie; Teboul, David; Lièvre, Astrid; Goasguen, Nicolas; Berger, Anne; Beaune, Philippe; Laurent-Puig, Pierre

2004-01-01

A novel member of the Wnt signalling pathway, Chibby, was recently identified. This protein inhibits Wnt/β-catenin mediated transcriptional activation by competing with Lef-1 (the transcription factor and target of β-catenin) to bind to β-catenin. This suggests that Chibby could be a tumour suppressor protein. The C22orf2 gene coding Chibby is located on chromosome 22, a region recurrently lost in colorectal cancer. Activation of the Wnt pathway is a major feature of colorectal cancer and occurs through inactivation of APC or activation of β-catenin. All of this led us to analyse the possible implication of Chibby in colorectal carcinogenesis. First, 36 tumour and matched normal colonic mucosa DNA were genotyped with five microsatellite markers located on chromosome 22 to search for loss of heterozygosity. Then, mutation screening of the C22orf2 coding sequence and splice sites was performed in the 36 tumour DNA. Finally, expression of Chibby was analysed by quantitative RT-PCR on 10 patients, 4 with loss of heterozygosity (LOH) on chromosome 22. Loss of heterozygosity involving the C22orf2 region was detected in 11 out of 36 patients (30%). Sequencing analysis revealed a known variant, rs3747174, in exon 5: T321C leading to a silent amino acid polymorphism A107A. Allelic frequencies were 0.69 and 0.31 for T and C variants respectively. No other mutation was detected. Among the 10 patients studied, expression analysis revealed that Chibby is overexpressed in 2 tumours and underexpressed in 1. No correlations were found with 22q LOH status. As no somatic mutation was detected in C22orf2 in 36 colorectal tumour DNA, our results do not support the implication of Chibby as a tumour suppressor in colorectal carcinogenesis. This was supported by the absence of underexpression of Chibby among the tumour samples with 22q LOH. The implication of other Wnt pathway members remains to be identified to explain the part of colorectal tumours without mutation in APC and β-catenin

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.

Clinical Impact of TP53 Gene Mutations in Diffuse Large B-Cell Lymphoma (DLBCL)

DEFF Research Database (Denmark)

Young, Ken H; Patten, Nancy; Truong, Sim

2009-01-01

Mutations of the TP53 tumor suppressor gene are associated with a poor clinical outcome in DLBCL patients treated with CHOP. The impact of TP53 mutations on clinical outcome of DLBCL patients treated with Rituxan-CHOP has not been comprehensively analyzed. The purpose of this study was to analyze...

Characterization of two second-site mutations preventing wild type protein aggregation caused by a dominant negative PMA1 mutant.

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Pilar Eraso

Full Text Available The correct biogenesis and localization of Pma1 at the plasma membrane is essential for yeast growth. A subset of PMA1 mutations behave as dominant negative because they produce aberrantly folded proteins that form protein aggregates, which in turn provoke the aggregation of the wild type protein. One approach to understand this dominant negative effect is to identify second-site mutations able to suppress the dominant lethal phenotype caused by those mutant alleles. We isolated and characterized two intragenic second-site suppressors of the PMA1-D378T dominant negative mutation. We present here the analysis of these new mutations that are located along the amino-terminal half of the protein and include a missense mutation, L151F, and an in-frame 12bp deletion that eliminates four residues from Cys409 to Ala412. The results show that the suppressor mutations disrupt the interaction between the mutant and wild type enzymes, and this enables the wild type Pma1 to reach the plasma membrane.

Mutations at Several Loci Cause Increased Expression of Ribonucleotide Reductase in Escherichia coli

Science.gov (United States)

Feeney, Morgan Anne; Ke, Na

2012-01-01

Production of deoxyribonucleotides for DNA synthesis is an essential and tightly regulated process. The class Ia ribonucleotide reductase (RNR), the product of the nrdAB genes, is required for aerobic growth of Escherichia coli. In catalyzing the reduction of ribonucleotides, two of the cysteines of RNR become oxidized, forming a disulfide bond. To regenerate active RNR, the cell uses thioredoxins and glutaredoxins to reduce the disulfide bond. Strains that lack thioredoxins 1 and 2 and glutaredoxin 1 do not grow because RNR remains in its oxidized, inactive form. However, suppressor mutations that lead to RNR overproduction allow glutaredoxin 3 to reduce sufficient RNR for growth of these mutant strains. We previously described suppressor mutations in the dnaA and dnaN genes that had such effects. Here we report the isolation of new mutations that lead to increased levels of RNR. These include mutations that were not known to influence production of RNR previously, such as a mutation in the hda gene and insertions in the nrdAB promoter region of insertion elements IS1 and IS5. Bioinformatic analysis raises the possibility that IS element insertion in this region represents an adaptive mechanism in nrdAB regulation in E. coli and closely related species. We also characterize mutations altering different amino acids in DnaA and DnaN from those isolated before. PMID:22247510

A complex interaction of imprinted and maternal-effect genes modifies sex determination in Odd Sex (Ods) mice.

Science.gov (United States)

Poirier, Christophe; Qin, Yangjun; Adams, Carolyn P; Anaya, Yanett; Singer, Jonathan B; Hill, Annie E; Lander, Eric S; Nadeau, Joseph H; Bishop, Colin E

2004-11-01

The transgenic insertional mouse mutation Odd Sex (Ods) represents a model for the long-range regulation of Sox9. The mutation causes complete female-to-male sex reversal by inducing a male-specific expression pattern of Sox9 in XX Ods/+ embryonic gonads. We previously described an A/J strain-specific suppressor of Ods termed Odsm1(A). Here we show that phenotypic sex depends on a complex interaction between the suppressor and the transgene. Suppression can be achieved only if the transgene is transmitted paternally. In addition, the suppressor itself exhibits a maternal effect, suggesting that it may act on chromatin in the early embryo.

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

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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

YNK1, the yeast homolog of human metastasis suppressor NM23, is required for repair of UV radiation- and etoposide-induced DNA damage

Energy Technology Data Exchange (ETDEWEB)

Yang Mengmeng; Jarrett, Stuart G.; Craven, Rolf [Department of Molecular and Biomedical Pharmacology, College of Medicine, University of Kentucky, Lexington, KY 40536-0298 (United States); Kaetzel, David M. [Department of Molecular and Biomedical Pharmacology, College of Medicine, University of Kentucky, Lexington, KY 40536-0298 (United States)], E-mail: dmkaetz@uky.edu

2009-01-15

In humans, NM23-H1 is a metastasis suppressor whose expression is reduced in metastatic melanoma and breast carcinoma cells, and which possesses the ability to inhibit metastatic growth without significant impact on the transformed phenotype. NM23-H1 exhibits three enzymatic activities in vitro, each with potential to maintain genomic stability, a 3'-5' exonuclease and two kinases, nucleoside diphosphate kinase (NDPK), and protein histidine kinase. Herein we have investigated the potential contributions of NM23 proteins to DNA repair in the yeast, Saccharomyces cerevisiae, which contains a single NM23 homolog, YNK1. Ablation of YNK1 delayed repair of UV- and etoposide-induced nuclear DNA damage by 3-6 h. However, YNK1 had no impact upon the kinetics of MMS-induced DNA repair. Furthermore, YNK1 was not required for repair of mitochondrial DNA damage. To determine whether the nuclear DNA repair deficit manifested as an increase in mutation frequency, the CAN1 forward assay was employed. An YNK1 deletion was associated with increased mutation rates following treatment with either UV (2.6x) or MMS (1.6x). Mutation spectral analysis further revealed significantly increased rates of base substitution and frameshift mutations following UV treatment in the ynk1{delta} strain. This study indicates a novel role for YNK1 in DNA repair in yeast, and suggests an anti-mutator function that may contribute to the metastasis suppressor function of NM23-H1 in humans.

YNK1, the yeast homolog of human metastasis suppressor NM23, is required for repair of UV radiation- and etoposide-induced DNA damage

International Nuclear Information System (INIS)

Yang Mengmeng; Jarrett, Stuart G.; Craven, Rolf; Kaetzel, David M.

2009-01-01

In humans, NM23-H1 is a metastasis suppressor whose expression is reduced in metastatic melanoma and breast carcinoma cells, and which possesses the ability to inhibit metastatic growth without significant impact on the transformed phenotype. NM23-H1 exhibits three enzymatic activities in vitro, each with potential to maintain genomic stability, a 3'-5' exonuclease and two kinases, nucleoside diphosphate kinase (NDPK), and protein histidine kinase. Herein we have investigated the potential contributions of NM23 proteins to DNA repair in the yeast, Saccharomyces cerevisiae, which contains a single NM23 homolog, YNK1. Ablation of YNK1 delayed repair of UV- and etoposide-induced nuclear DNA damage by 3-6 h. However, YNK1 had no impact upon the kinetics of MMS-induced DNA repair. Furthermore, YNK1 was not required for repair of mitochondrial DNA damage. To determine whether the nuclear DNA repair deficit manifested as an increase in mutation frequency, the CAN1 forward assay was employed. An YNK1 deletion was associated with increased mutation rates following treatment with either UV (2.6x) or MMS (1.6x). Mutation spectral analysis further revealed significantly increased rates of base substitution and frameshift mutations following UV treatment in the ynk1Δ strain. This study indicates a novel role for YNK1 in DNA repair in yeast, and suggests an anti-mutator function that may contribute to the metastasis suppressor function of NM23-H1 in humans

Modulation of immune response by alloactivated suppressor T cells

International Nuclear Information System (INIS)

Bernstein, A.; Sopori, M.L.; Gose, J.E.; Sondel, P.M.

1979-01-01

These studies show that there may be several different kinds of suppressor cells, each activated by different pathways and able to suppress different parts of the immune response either specifically or nonspecifically. As such, the physiology of one type of suppressor cell need not necessarily apply to that of another type of suppressor. Thus we emphasize the trap that the suppressor cell option provides: that is, virtually any previously inexplicable in vitro and in vivo immune phenomenon can always be adequately accounted for by evoking a suppressor mechanism, either by suppressing the response or suppressing the suppressor

Germ line p53 mutations in a familial syndrome of breast cancer, sarcomas, and other neoplasms.

Science.gov (United States)

Malkin, D; Li, F P; Strong, L C; Fraumeni, J F; Nelson, C E; Kim, D H; Kassel, J; Gryka, M A; Bischoff, F Z; Tainsky, M A

1990-11-30

Familial cancer syndromes have helped to define the role of tumor suppressor genes in the development of cancer. The dominantly inherited Li-Fraumeni syndrome (LFS) is of particular interest because of the diversity of childhood and adult tumors that occur in affected individuals. The rarity and high mortality of LFS precluded formal linkage analysis. The alternative approach was to select the most plausible candidate gene. The tumor suppressor gene, p53, was studied because of previous indications that this gene is inactivated in the sporadic (nonfamilial) forms of most cancers that are associated with LFS. Germ line p53 mutations have been detected in all five LFS families analyzed. These mutations do not produce amounts of mutant p53 protein expected to exert a trans-dominant loss of function effect on wild-type p53 protein. The frequency of germ line p53 mutations can now be examined in additional families with LFS, and in other cancer patients and families with clinical features that might be attributed to the mutation.

p53 tumor suppressor gene: significance in neoplasia - a review

International Nuclear Information System (INIS)

Alam, J.M.

2000-01-01

p53 is a tumor suppressor gene located on chromosome 17p13.1. Its function includes cell cycle control and apoptosis. Loss of p53 function, either due to decreased level or genetic transformation, is associated with loss of cell cycle control, decrease, apoptosis and genomic modification, such mutation of p53 gene is now assessed and the indicator of neoplasia of cancer of several organs and cell types, p53 has demonstrated to have critical role in defining various progressive stages of neoplasia, therapeutic strategies and clinical application. The present review briefly describes function of p53 in addition to its diagnostic and prognostic significance in detecting several types of neoplasia. (author)

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 < 0.1), in comparison to zero of 18,055 autosomal and PAR genes (Fisher's exact P < 0.0001). Male-biased mutations in 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.

MMS sensitivity of all amino acid-requiring mutants in aspergillus and its suppression by mutations in a single gene.

Science.gov (United States)

Käfer, E

1987-04-01

All available amino acid-requiring mutants of Aspergillus nidulans were found to be hypersensitive to MMS (methyl methanesulfonate) to various degrees. On MMS media, secondary mutations could be selected which suppress this MMS sensitivity but do not affect the requirement. Many such mutations were analyzed and found to be alleles of one gene, smsA (= suppressor of MMS sensitivity), which mapped distal on the right arm of chromosome V. This gene is more likely to be involved in general regulation of amino acid biosynthesis than MMS uptake, since a variety of pathway interactions were clearly modified by smsA suppressors in the absence of MMS.

G673 could be a novel mutational hot spot for intragenic suppressors of pheS5 lesion in Escherichia coli.

Science.gov (United States)

Ponmani, Thangaraj; Munavar, M Hussain

2014-06-01

The pheS5 Ts mutant of Escherichia coli defined by a G293 → A293 transition, which is responsible for thermosensitive Phenylalanyl-tRNA synthetase has been well studied at both biochemical and molecular level but genetic analyses pertaining to suppressors of pheS5 were hard to come by. Here we have systematically analyzed a spectrum of Temperature-insensitive derivatives isolated from pheS5 Ts mutant and identified two intragenic suppressors affecting the same base pair coordinate G673 (pheS19 defines G673 → T673 ; Gly225 → Cys225 and pheS28 defines G673 → C673 ; Gly225 → Arg225). In fact in the third derivative, the intragenic suppressor originally named pheS43 (G673 → C673 transversion) is virtually same as pheS28. In the fourth case, the very pheS5 lesion itself has got changed from A293 → T293 (named pheS40). Cloning of pheS(+), pheS5, pheS5-pheS19, pheS5-pheS28 alleles into pBR322 and introduction of these clones into pheS5 mutant revealed that excess of double mutant protein is not at all good for the survival of cells at 42°C. These results clearly indicate a pivotal role for Gly225 in the structural/functional integrity of alpha subunit of E. coli PheRS enzyme and it is proposed that G673 might define a hot spot for intragenic suppressors of pheS5. © 2014 The Authors. MicrobiologyOpen published by John Wiley & Sons Ltd.

A BRCA2 mutation incorrectly mapped in the original BRCA2 reference sequence, is a common West Danish founder mutation disrupting mRNA splicing

DEFF Research Database (Denmark)

Thomassen, Mads; Pedersen, Inge Søkilde; Vogel, Ida

2011-01-01

Inherited mutations in the tumor suppressor genes BRCA1 and BRCA2 predispose carriers to breast and ovarian cancer. The authors have identified a mutation in BRCA2, 7845+1G>A (c.7617+1G>A), not previously regarded as deleterious because of incorrect mapping of the splice junction in the originally...... published genomic reference sequence. This reference sequence is generally used in many laboratories and it maps the mutation 16 base pairs inside intron 15. However, according to the recent reference sequences the mutation is located in the consensus donor splice sequence. By reverse transcriptase analysis......, loss of exon 15 in the final transcript interrupting the open reading frame was demonstrated. Furthermore, the mutation segregates with a cancer phenotype in 18 Danish families. By genetic analysis of more than 3,500 Danish breast/ovarian cancer risk families, the mutation was identified as the most...

An unusual characteristic "flower-like" pattern: flash suppressor burns.

Science.gov (United States)

Gurcan, Altun

2012-04-01

The case on contact shots from firearms with a flash suppressor is rare. When a rifle fitted with a flash suppressor is fired, the emerging soot-laden gas in the barrel escapes from the slits of the flash suppressor. If the shot is contact or near contact, the flash suppressor will produce a characteristic "flower-like" pattern of seared, blackened zones around the entrance. This paper presents the injury pattern of the flash suppressor in a 29-year-old man who committed suicide with a G3 automatic infantry rifle.

Suppression of the Escherichia coli ssb-1 mutation by an allele of groEL.

OpenAIRE

Ruben, S M; VanDenBrink-Webb, S E; Rein, D C; Meyer, R R

1988-01-01

A series of spontaneous suppressors to the temperature-sensitive phenotype of the single-stranded DNA-binding protein mutation ssb-1 were isolated. A genomic library of EcoRI fragments from one of these suppressor strains was prepared by using pBR325 as the cloning vector. A 10.0-kilobase class of inserts was identified as carrying the ssb-1 gene itself. A second class of 8.3-kilobase inserts was shown to contain the groE region by (i) restriction analysis, (ii) Southern hybridization of the ...

Leucine insertion caused by a yeast amber suppressor

Energy Technology Data Exchange (ETDEWEB)

Liebman, S W [Univ. of Rochester School of Medicine and Dentistry, NY; Stewart, J W; Parker, J H; Sherman, F

1977-01-01

The amber suppressor SUP52 can cause the production of approximately 15 to 20% of the normal amount of iso-l-cytochrome c when coupled to the amber (UAG) mutant cyc1-76. The suppressed iso-l-cytochrome c contains a residue of leucine at the position corresponding to the site of the amber codon. SUP52 also supresses another amber allele cyc1-179, but only with a low efficiency of approximately 2%. It does not appear to act at all on ochre (UAA) mutants. SUP52 was found to be on the left arm of chromosome X closely linked to the centromere.

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

Minor Threonine Dehydratase Encoded Within the Threonine Synthetic Region of Bacillus subtilis1

Science.gov (United States)

Vapnek, Daniel; Greer, Sheldon

1971-01-01

Challenging auxotrophs on metabolites that are precursors of a biosynthetic step involving a mutated enzyme has revealed a new class of suppressor mutations which act by derepressing a minor enzyme activity not normally detected in the wild-type strain. These indirect, partial suppressor mutations which allow isoleucine auxotrophs to grow on homoserine or threonine have been analyzed to determine their effect on enzymes involved in the biosynthesis of these amino acids. It has been found that one class of these suppressor mutations (sprA) leads to the derepression of homoserine kinase, homoserine dehydrogenase, and a minor threonine dehydratase that is not sufficiently active to be detected in the wild-type strain. The gene encoding this second threonine dehydratase activity has been found to be located between the structural genes for homoserine kinase and homoserine dehydrogenase. The results of these experiments indicate that plating of auxotrophs on precursors of a biosynthetic step involving mutated enzymes could prove to be a valuable method for the detection of regulatory mutants as well as a possible tool in studying the evolution of biochemical pathways. PMID:4997544

Biological evidence that SOCS-2 can act either as an enhancer or suppressor of growth hormone signaling

DEFF Research Database (Denmark)

Greenhalgh, Christopher J; Metcalf, Donald; Thaus, Anne L

2002-01-01

Suppressor of cytokine signaling (SOCS)-2 is a member of a family of intracellular proteins implicated in the negative regulation of cytokine signaling. The generation of SOCS-2-deficient mice, which grow to one and a half times the size of their wild-type littermates, suggests that SOCS-2 may at...

Intragenic suppressor of Osiaa23 revealed a conserved tryptophan residue crucial for protein-protein interactions.

Directory of Open Access Journals (Sweden)

Jun Ni

Full Text Available The Auxin/Indole-3-Acetic Acid (Aux/IAA and Auxin Response Factor (ARF are two important families that play key roles in auxin signal transduction. Both of the families contain a similar carboxyl-terminal domain (Domain III/IV that facilitates interactions between these two families. In spite of the importance of protein-protein interactions among these transcription factors, the mechanisms involved in these interactions are largely unknown. In this study, we isolated six intragenic suppressors of an auxin insensitive mutant, Osiaa23. Among these suppressors, Osiaa23-R5 successfully rescued all the defects of the mutant. Sequence analysis revealed that an amino acid substitution occurred in the Tryptophan (W residue in Domain IV of Osiaa23. Yeast two-hybrid experiments showed that the mutation in Domain IV prevents the protein-protein interactions between Osiaa23 and OsARFs. Phylogenetic analysis revealed that the W residue is conserved in both OsIAAs and OsARFs. Next, we performed site-specific amino acid substitutions within Domain IV of OsARFs, and the conserved W in Domain IV was exchanged by Serine (S. The mutated OsARF(WSs can be released from the inhibition of Osiaa23 and maintain the transcriptional activities. Expression of OsARF(WSs in Osiaa23 mutant rescued different defects of the mutant. Our results suggest a previously unknown importance of Domain IV in both families and provide an indirect way to investigate functions of OsARFs.

Complexes between the LKB1 tumor suppressor, STRADα/β and MO25α/β are upstream kinases in the AMP-activated protein kinase cascade

Directory of Open Access Journals (Sweden)

Alessi Dario R

2003-09-01

Full Text Available Abstract Background The AMP-activated protein kinase (AMPK cascade is a sensor of cellular energy charge that acts as a 'metabolic master switch' and inhibits cell proliferation. Activation requires phosphorylation of Thr172 of AMPK within the activation loop by upstream kinases (AMPKKs that have not been identified. Recently, we identified three related protein kinases acting upstream of the yeast homolog of AMPK. Although they do not have obvious mammalian homologs, they are related to LKB1, a tumor suppressor that is mutated in the human Peutz-Jeghers cancer syndrome. We recently showed that LKB1 exists as a complex with two accessory subunits, STRADα/β and MO25α/β. Results We report the following observations. First, two AMPKK activities purified from rat liver contain LKB1, STRADα and MO25α, and can be immunoprecipitated using anti-LKB1 antibodies. Second, both endogenous and recombinant complexes of LKB1, STRADα/β and MO25α/β activate AMPK via phosphorylation of Thr172. Third, catalytically active LKB1, STRADα or STRADβ and MO25α or MO25β are required for full activity. Fourth, the AMPK-activating drugs AICA riboside and phenformin do not activate AMPK in HeLa cells (which lack LKB1, but activation can be restored by stably expressing wild-type, but not catalytically inactive, LKB1. Fifth, AICA riboside and phenformin fail to activate AMPK in immortalized fibroblasts from LKB1-knockout mouse embryos. Conclusions These results provide the first description of a physiological substrate for the LKB1 tumor suppressor and suggest that it functions as an upstream regulator of AMPK. Our findings indicate that the tumors in Peutz-Jeghers syndrome could result from deficient activation of AMPK as a consequence of LKB1 inactivation.

p16 mutation spectrum in the premalignant condition Barrett's esophagus.

Directory of Open Access Journals (Sweden)

Thomas G Paulson

Full Text Available BACKGROUND: Mutation, promoter hypermethylation and loss of heterozygosity involving the tumor suppressor gene p16 (CDKN2a/INK4a have been detected in a wide variety of human cancers, but much less is known concerning the frequency and spectrum of p16 mutations in premalignant conditions. METHODS AND FINDINGS: We have determined the p16 mutation spectrum for a cohort of 304 patients with Barrett's esophagus, a premalignant condition that predisposes to the development of esophageal adenocarcinoma. Forty seven mutations were detected by sequencing of p16 exon 2 in 44 BE patients (14.5% with a mutation spectrum consistent with that caused by oxidative damage and chronic inflammation. The percentage of patients with p16 mutations increased with increasing histologic grade. In addition, samples from 3 out of 19 patients (15.8% who underwent esophagectomy were found to have mutations. CONCLUSIONS: The results of this study suggest the environment of the esophagus in BE patients can both generate and select for clones with p16 mutations.

Induction of suppressor cells in vitro by Candida albicans.

Science.gov (United States)

Cuff, C F; Rogers, C M; Lamb, B J; Rogers, T J

1986-06-01

Normal splenocytes cultured with Formalin-killed Candida albicans were shown to acquire significant suppressor cell activity in a period of 3 days. These cells were found to suppress both the phytohemagglutinin-induced mitogen response as well as the anti-sheep erythrocyte antibody response. Experiments were carried out to determine the nature of the suppressor cell population. Results showed that these cells were not susceptible to treatment with anti-Thy 1 antibody and complement. Panning experiments showed that the suppressor cells were not plastic-adherent or Mac-1 antigen-positive. The suppressor cells were, however, adherent to anti-mouse immunoglobulin (F(ab')2-fragment)-coated dishes. Additional experiments showed that the suppressor cell activity was susceptible to treatment with monoclonal anti-Lyb 2.1 antibody and complement. These results suggest that the suppressor cell induced in vitro by Candida is a member of the B-lymphocyte lineage.

Off and back-on again: a tumor suppressor's tale.

Science.gov (United States)

Acosta, Jonuelle; Wang, Walter; Feldser, David M

2018-06-01

Tumor suppressor genes play critical roles orchestrating anti-cancer programs that are both context dependent and mechanistically diverse. Beyond canonical tumor suppressive programs that control cell division, cell death, and genome stability, unexpected tumor suppressor gene activities that regulate metabolism, immune surveillance, the epigenetic landscape, and others have recently emerged. This diversity underscores the important roles these genes play in maintaining cellular homeostasis to suppress cancer initiation and progression, but also highlights a tremendous challenge in discerning precise context-specific programs of tumor suppression controlled by a given tumor suppressor. Fortunately, the rapid sophistication of genetically engineered mouse models of cancer has begun to shed light on these context-dependent tumor suppressor activities. By using techniques that not only toggle "off" tumor suppressor genes in nascent tumors, but also facilitate the timely restoration of gene function "back-on again" in disease specific contexts, precise mechanisms of tumor suppression can be revealed in an unbiased manner. This review discusses the development and implementation of genetic systems designed to toggle tumor suppressor genes off and back-on again and their potential to uncover the tumor suppressor's tale.

Mutation and Methylation Analysis of the Chromodomain-Helicase-DNA Binding 5 Gene in Ovarian Cancer

Directory of Open Access Journals (Sweden)

Kylie L. Gorringe

2008-11-01

Full Text Available Chromodomain, helicase, DNA binding 5 (CHD5 is a member of a subclass of the chromatin remodeling Swi/Snf proteins and has recently been proposed as a tumor suppressor in a diverse range of human cancers. We analyzed all 41 coding exons of CHD5 for somatic mutations in 123 primary ovarian cancers as well as 60 primary breast cancers using high-resolution melt analysis. We also examined methylation of the CHD5 promoter in 48 ovarian cancer samples by methylation-specific single-stranded conformation polymorphism and bisulfite sequencing. In contrast to previous studies, no mutations were identified in the breast cancers, but somatic heterozygous missense mutations were identified in 3 of 123 ovarian cancers. We identified promoter methylation in 3 of 45 samples with normal CHD5 and in 2 of 3 samples with CHD5 mutation, suggesting these tumors may have biallelic inactivation of CHD5. Hemizygous copy number loss at CHD5 occurred in 6 of 85 samples as assessed by single nucleotide polymorphism array. Tumors with CHD5 mutation or methylation were more likely to have mutation of KRAS or BRAF (P = .04. The aggregate frequency of CHD5 haploinsufficiency or inactivation is 16.2% in ovarian cancer. Thus, CHD5 may play a role as a tumor suppressor gene in ovarian cancer; however, it is likely that there is another target of the frequent copy number neutral loss of heterozygosity observed at 1p36.

Genistein inhibits proliferation of colon cancer cells by attenuating a negative effect of epidermal growth factor on tumor suppressor FOXO3 activity

International Nuclear Information System (INIS)

Qi, Wentao; Weber, Christopher R; Wasland, Kaarin; Savkovic, Suzana D

2011-01-01

Soy consumption is associated with a lower incidence of colon cancer which is believed to be mediated by one of its of components, genistein. Genistein may inhibit cancer progression by inducing apoptosis or inhibiting proliferation, but mechanisms are not well understood. Epidermal growth factor (EGF)-induced proliferation of colon cancer cells plays an important role in colon cancer progression and is mediated by loss of tumor suppressor FOXO3 activity. The aim of this study was to assess if genistein exerts anti-proliferative properties by attenuating the negative effect of EGF on FOXO3 activity. The effect of genistein on proliferation stimulated by EGF-mediated loss of FOXO3 was examined in human colonic cancer HT-29 cells. EGF-induced FOXO3 phosphorylation and translocation were assessed in the presence of genistein. EGF-mediated loss of FOXO3 interactions with p53 (co-immunoprecipitation) and promoter of p27kip1 (ChIP assay) were examined in presence of genistein in cells with mutated p53 (HT-29) and wild type p53 (HCT116). Silencing of p53 determined activity of FOXO3 when it is bound to p53. Genistein inhibited EGF-induced proliferation, while favoring dephosphorylation and nuclear retention of FOXO3 (active state) in colon cancer cells. Upstream of FOXO3, genistein acts via the PI3K/Akt pathway to inhibit EGF-stimulated FOXO3 phosphorylation (i.e. favors active state). Downstream, EGF-induced disassociation of FOXO3 from mutated tumor suppressor p53, but not wild type p53, is inhibited by genistein favoring FOXO3-p53(mut) interactions with the promoter of the cell cycle inhibitor p27kip1 in colon cancer cells. Thus, the FOXO3-p53(mut) complex leads to elevated p27kip1 expression and promotes cell cycle arrest. These novel anti-proliferative mechanisms of genistein suggest a possible role of combining genistein with other chemoreceptive agents for the treatment of colon cancer

Tumor suppressor p53 biology, its role in radioresponse and the analysis of p53 mutation/expression among Filipino breast cancers

International Nuclear Information System (INIS)

Deocaris, Custer C.

2004-01-01

Ionizing radiation remains one of the most effective tools for the treatment of breast cancer. It combines properties of a potent DNA-damaging agent and high degree of spatial specificity to the target tissue. Nonetheless, there remain considerable differences in the outcome for treatment of tumors of differing histological type treated by radiotherapy. The identification of predictive indicators of radiosensitivity is crucial for selecting patients suited for preoperative radiotherapy as well as those unwarranted for postoperative treatments. To improve prognostication, numerous genes involved in the breast carcinogenesis have been studied and thus far over the last decade several multi-center researches converge on the role of tumor suppressor p53 in tumor biology. The p53 gene is located on the short arm of chromosome 17 and encodes a 53-kd nuclear protein, p-53, also referred to as 'the guardian of the genome', it orchestrates multiple cellular processes such as cell growth control, DNA repair and programmed cell death. During radiotherapy, genotoxic damage induces p53 overexpression in order to control the rate of proliferating damaged cells, repair damage or induce the apoptotic pathway. Its molecular inactivation in a tumor cell, typically by a point mutation, leads to chemo/radio resistance due to the inability of the molecule to trigger p53-dependent programmed cell death

Classification of suppressor additives based on synergistic and antagonistic ensemble effects

Energy Technology Data Exchange (ETDEWEB)

Broekmann, P., E-mail: peter.broekmann@iac.unibe.ch [BASF SE, Global Business Unit Electronic Materials, 67056 Ludwigshafen (Germany); Department of Chemistry and Biochemistry, University of Bern, Bern (Switzerland); Fluegel, A.; Emnet, C.; Arnold, M.; Roeger-Goepfert, C.; Wagner, A. [BASF SE, Global Business Unit Electronic Materials, 67056 Ludwigshafen (Germany); Hai, N.T.M. [Department of Chemistry and Biochemistry, University of Bern, Bern (Switzerland); Mayer, D. [BASF SE, Global Business Unit Electronic Materials, 67056 Ludwigshafen (Germany)

2011-05-01

Highlights: > Three fundamental types of suppressor additives for copper electroplating could be identified by means of potential transient measurements. > These suppressor additives differ in their synergistic and antagonistic interplay with anions that are chemisorbed on the metallic copper surface during electrodeposition. > In addition these suppressor chemistries reveal different barrier properties with respect to cupric ions and plating additives (Cl, SPS). - Abstract: Three fundamental types of suppressor additives for copper electroplating could be identified by means of potential transient measurements. These suppressor additives differ in their synergistic and antagonistic interplay with anions that are chemisorbed on the metallic copper surface during electrodeposition. In addition these suppressor chemistries reveal different barrier properties with respect to cupric ions and plating additives (Cl, SPS). While the type-I suppressor selectively forms efficient barriers for copper inter-diffusion on chloride-terminated electrode surfaces we identified a type-II suppressor that interacts non-selectively with any kind of anions chemisorbed on copper (chloride, sulfate, sulfonate). Type-I suppressors are vital for the superconformal copper growth mode in Damascene processing and show an antagonistic interaction with SPS (Bis-Sodium-Sulfopropyl-Disulfide) which involves the deactivation of this suppressor chemistry. This suppressor deactivation is rationalized in terms of compositional changes in the layer of the chemisorbed anions due to the competition of chloride and MPS (Mercaptopropane Sulfonic Acid) for adsorption sites on the metallic copper surface. MPS is the product of the dissociative SPS adsorption within the preexisting chloride matrix on the copper surface. The non-selectivity in the adsorption behavior of the type-II suppressor is rationalized in terms of anion/cation pairing effects of the poly-cationic suppressor and the anion-modified copper

An unusual characteristic “flower-like” pattern: flash suppressor burns

OpenAIRE

Gurcan, Altun

2012-01-01

The case on contact shots from firearms with a flash suppressor is rare. When a rifle fitted with a flash suppressor is fired, the emerging soot-laden gas in the barrel escapes from the slits of the flash suppressor. If the shot is contact or near contact, the flash suppressor will produce a characteristic “flower-like” pattern of seared, blackened zones around the entrance. This paper presents the injury pattern of the flash suppressor in a 29-year-old man who committed suicide with a G3 aut...

An unusual characteristic “flower-like” pattern: flash suppressor burns

Science.gov (United States)

Gurcan, Altun

2012-01-01

The case on contact shots from firearms with a flash suppressor is rare. When a rifle fitted with a flash suppressor is fired, the emerging soot-laden gas in the barrel escapes from the slits of the flash suppressor. If the shot is contact or near contact, the flash suppressor will produce a characteristic “flower-like” pattern of seared, blackened zones around the entrance. This paper presents the injury pattern of the flash suppressor in a 29-year-old man who committed suicide with a G3 automatic infantry rifle. PMID:23935280

TP53 mutations in clinically normal mucosa adjacent to oral carcinomas

DEFF Research Database (Denmark)

Thode, Christenze; Bilde, Anders; von Buchwald, Christian

2010-01-01

BACKGROUND: The tumour-suppressor protein p53 often accumulates in histologically normal epithelium adjacent to oral squamous cell carcinomas (OSCC). We investigated whether this was associated with mutations in TP53, the gene for p53, and might implicate impending malignancy. METHODS: Specimens...... products were separated by denatured gradient gel electrophoresis. Fragments with a deviant DGEE pattern were sequenced. RESULTS: TP53 mutations were found in six of 18 tumours. Fourteen specimens contained histologically normal mucosa adjacent to the tumour; 13 of these showed small clusters of p53...

Mutations in ash1 and trx enhance P-element-dependent silencing in Drosophila melanogaster.

Science.gov (United States)

McCracken, Allen; Locke, John

2016-08-01

In Drosophila melanogaster, the mini-w(+) transgene in Pci is normally expressed throughout the adult eye; however, when other P or KP elements are present, a variegated-eye phenotype results, indicating random w(+) silencing during development called P-element-dependent silencing (PDS). Mutant Su(var)205 and Su(var)3-7 alleles act as haplo-suppressors/triplo-enhancers of this variegated phenotype, indicating that these heterochromatic modifiers act dose dependently in PDS. Previously, we recovered a spontaneous mutation of P{lacW}ci(Dplac) called P{lacW}ci(DplacE1) (E1) that variegated in the absence of P elements, presumably due to the insertion of an adjacent gypsy element. From a screen for genetic modifiers of E1 variegation, we describe here the isolation of five mutations in ash1 and three in trx that enhance the E1 variegated phenotype in a dose-dependent and cumulative manner. These mutant alleles enhance PDS at E1, and in E1/P{lacW}ci(Dplac), but suppress position effect variegation (PEV) at In(1)w(m)(4). This opposite action is consistent with a model where ASH1 and TRX mark transcriptionally active chromatin domains. If ASH1 or TRX function is lost or reduced, heterochromatin can spread into these domains creating a sink that diverts heterochromatic proteins from other variegating locations, which then may express a suppressed phenotype.

P53 tumor suppressor gene and protein expression is altered in cell lines derived from spontaneous and alpha-radiation-induced canine lung tumors

International Nuclear Information System (INIS)

Tierney, L.A.; Johnson, N.F.; Lechner, J.F.

1994-01-01

Mutations in the p53 tumor suppressor gene are the most frequently occurring gene alterations in malignant human cancers, including lung cancer. In lung cancer, common point mutations within conserved exons of the p53 gene result in a stabilized form of mutant protein which is detectable in most cases by immunohistochemistry. In addition to point mutations, allelic loss, rearrangements, and deletions of the p53 gene have also been detected in both human and rodent tumors. It has been suggested that for at least some epithelial neoplasms, the loss of expression of wild-type p53 protein may be more important for malignant transformation than the acquisition of activating mutations. Mechanisms responsible for the loss of expression of wild-type protein include gene deletion or rearrangement, nonsense or stop mutations, mutations within introns or upstream regulatory regions of the gene, and accelerated rates of degradation of the protein by DNA viral oncoproteins

Mutation analysis of suppressor of cytokine signalling 3, a candidate gene in Type 1 diabetes and insulin sensitivity

DEFF Research Database (Denmark)

Gylvin, T; Nolsøe, R; Hansen, T

2004-01-01

Beta cell loss in Type 1 and Type 2 diabetes mellitus may result from apoptosis and necrosis induced by inflammatory mediators. The suppressor of cytokine signalling (SOCS)-3 is a natural inhibitor of cytokine signalling and also influences insulin signalling. SOCS3 could therefore be a candidate...... gene in the development of Type 1 and Type 2 diabetes mellitus....

Mutations in ribosomal proteins, RPL4 and RACK1, suppress the phenotype of a thermospermine-deficient mutant of Arabidopsis thaliana.

Directory of Open Access Journals (Sweden)

Jun-ichi Kakehi

Full Text Available Thermospermine acts in negative regulation of xylem differentiation and its deficient mutant of Arabidopsis thaliana, acaulis5 (acl5, shows excessive xylem formation and severe dwarfism. Studies of two dominant suppressors of acl5, sac51-d and sac52-d, have revealed that SAC51 and SAC52 encode a transcription factor and a ribosomal protein L10 (RPL10, respectively, and these mutations enhance translation of the SAC51 mRNA, which contains conserved upstream open reading frames in the 5' leader. Here we report identification of SAC53 and SAC56 responsible for additional suppressors of acl5. sac53-d is a semi-dominant allele of the gene encoding a receptor for activated C kinase 1 (RACK1 homolog, a component of the 40S ribosomal subunit. sac56-d represents a semi-dominant allele of the gene for RPL4. We show that the GUS reporter activity driven by the CaMV 35S promoter plus the SAC51 5' leader is reduced in acl5 and restored by sac52-d, sac53-d, and sac56-d as well as thermospermine. Furthermore, the SAC51 mRNA, which may be a target of nonsense-mediated mRNA decay, was found to be stabilized in these ribosomal mutants and by thermospermine. These ribosomal proteins are suggested to act in the control of uORF-mediated translation repression of SAC51, which is derepressed by thermospermine.

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.

Association of the germline TP53 R337H mutation with breast cancer in southern Brazil

International Nuclear Information System (INIS)

Assumpção, Juliana G; Zeferino, Luiz Carlos; Dufloth, Rozany M; Brandalise, Silvia Regina; Yunes, José Andres; Seidinger, Ana Luíza; Mastellaro, Maria José; Ribeiro, Raul C; Zambetti, Gerard P; Ganti, Ramapriya; Srivastava, Kumar; Shurtleff, Sheila; Pei, Deqing

2008-01-01

The germline TP53-R337H mutation is strongly associated with pediatric adrenocortical tumors (ACT) in southern Brazil; it has low penetrance and limited tissue specificity in most families and therefore is not associated with Li-Fraumeni syndrome. However, other tumor types, mainly breast cancer, have been observed in carriers of several unrelated kindreds, raising the possibility that the R337H mutation may also contribute to breast tumorigenesis in a genetic background-specific context. We conducted a case-control study to determine the prevalence of the R337H mutation by sequencing TP53 exon 10 in 123 women with breast cancer and 223 age- and sex-matched control subjects from southern Brazil. Fisher's test was used to compare the prevalence of the R337H. The R337H mutation was found in three patients but in none of the controls (p = 0.0442). Among the carriers, two had familial history of cancer meeting the Li-Fraumeni-like criteria. Remarkably, tumors in each of these three cases underwent loss of heterozygosity by eliminating the mutant TP53 allele rather than the wild-type allele. Polymorphisms were identified within the TP53 (R72P and Ins16) and MDM2 (SNP309) genes that may further diminish TP53 tumor suppressor activity. These results demonstrate that the R337H mutation can significantly increase the risk of breast cancer in carriers, which likely depends on additional cooperating genetic factors. These findings are also important for understanding how low-penetrant mutant TP53 alleles can differentially influence tumor susceptibility

Measurand transient signal suppressor

Science.gov (United States)

Bozeman, Richard J., Jr. (Inventor)

1994-01-01

A transient signal suppressor for use in a controls system which is adapted to respond to a change in a physical parameter whenever it crosses a predetermined threshold value in a selected direction of increasing or decreasing values with respect to the threshold value and is sustained for a selected discrete time interval is presented. The suppressor includes a sensor transducer for sensing the physical parameter and generating an electrical input signal whenever the sensed physical parameter crosses the threshold level in the selected direction. A manually operated switch is provided for adapting the suppressor to produce an output drive signal whenever the physical parameter crosses the threshold value in the selected direction of increasing or decreasing values. A time delay circuit is selectively adjustable for suppressing the transducer input signal for a preselected one of a plurality of available discrete suppression time and producing an output signal only if the input signal is sustained for a time greater than the selected suppression time. An electronic gate is coupled to receive the transducer input signal and the timer output signal and produce an output drive signal for energizing a control relay whenever the transducer input is a non-transient signal which is sustained beyond the selected time interval.

Suppressor Effects of Coping Strategies on Resilience

Science.gov (United States)

Yoon, Jae ho; Lee, Ji hae; Lee, Chae Yeon; Cho, Minhee; Lee, Sang Min

2014-01-01

The purpose of the current study is to demonstrate a significant suppressor effect among coping strategies on resilience. Two different samples were used to replicate the suppressor effect. Participants in the first example were 391 adolescents (middle school students) in Korea, and participants in the second example were 282 young adults…

Structural characterization of suppressor lipids by high-resolution mass spectrometry

DEFF Research Database (Denmark)

Rovillos, Mary Joy; Pauling, Josch Konstantin; Hannibal-Bach, Hans Kristian

2016-01-01

RATIONALE: Suppressor lipids were originally identified in 1993 and reported to encompass six lipid classes that enable Saccharomyces cerevisiae to live without sphingolipids. Structural characterization, using non-mass spectrometric approaches, revealed that these suppressor lipids are very long...... chain fatty acid (VLCFA)-containing glycerophospholipids with polar head groups that are typically incorporated into sphingolipids. Here we report, for the first time, the structural characterization of the yeast suppressor lipids using high-resolution mass spectrometry. METHODS: Suppressor lipids were...... isolated by preparative chromatography and subjected to structural characterization using hybrid quadrupole time-of-flight and ion trap-orbitrap mass spectrometry. RESULTS: Our investigation recapitulates the overall structural features of the suppressor lipids and provides an in-depth characterization...

Mutational specificity of SOS mutagenesis

International Nuclear Information System (INIS)

Kato, Takeshi

1986-01-01

In an approach to the isolation of mutants of E. coli unable to produce mutations by ultraviolet light, the author has found new umuC-mutants. Their properties could be explained by ''SOS hypothesis of Radman and Witkin'', which has now been justified by many investigators. Analysis of the umuC region of E. coli chromosome cloned in pSK 100 has led to the conclusion that two genes, umuD and umuC, having the capacity of mutation induction express in the same mechanism as that of SOS genes, which is known to be inhibited by LexA protein bonding to ''SOS box'' found at promotor region. Suppressor analysis for mutational specificity has revealed: (i) umuDC-independent mutagens, such as EMS and (oh) 4 Cy, induce selected base substitution alone; and (ii) umuDC-dependent mutagens, such as X-rays and gamma-rays, induce various types of base substitution simultaneously, although they have mutational specificity. In the umuDC-dependent processes of basechange mutagenesis, the spectra of base substitution were a mixture of base substitution reflecting the specific base damages induced by individual mutagens and nonspecific base substitution. In conclusion, base substitution plays the most important role in umuDC-dependent mutagenesis, although mutagenesis of umuDC proteins remains uncertain. (Namekawa, K.)

Truncating PREX2 mutations activate its GEF activity and alter gene expression regulation in NRAS-mutant melanoma

KAUST Repository

Lissanu Deribe, Yonathan

2016-03-01

PREX2 (phosphatidylinositol-3,4,5-triphosphate-dependent Rac-exchange factor 2) is a PTEN (phosphatase and tensin homolog deleted on chromosome 10) binding protein that is significantly mutated in cutaneous melanoma and pancreatic ductal adenocarcinoma. Here, genetic and biochemical analyses were conducted to elucidate the nature and mechanistic basis of PREX2 mutation in melanoma development. By generating an inducible transgenic mouse model we showed an oncogenic role for a truncating PREX2 mutation (PREX2E824*) in vivo in the context of mutant NRAS. Using integrative cross-species gene expression analysis, we identified deregulated cell cycle and cytoskeleton organization as significantly perturbed biological pathways in PREX2 mutant tumors. Mechanistically, truncation of PREX2 activated its Rac1 guanine nucleotide exchange factor activity, abolished binding to PTEN and activated the PI3K (phosphatidyl inositol 3 kinase)/Akt signaling pathway. We further showed that PREX2 truncating mutations or PTEN deletion induces down-regulation of the tumor suppressor and cell cycle regulator CDKN1C (also known as p57KIP2). This down-regulation occurs, at least partially, through DNA hypomethylation of a differentially methylated region in chromosome 11 that is a known regulatory region for expression of the CDKN1C gene. Together, these findings identify PREX2 as a mediator of NRAS-mutant melanoma development that acts through the PI3K/PTEN/Akt pathway to regulate gene expression of a cell cycle regulator.

Truncating PREX2 mutations activate its GEF activity and alter gene expression regulation in NRAS-mutant melanoma.

Science.gov (United States)

Lissanu Deribe, Yonathan; Shi, Yanxia; Rai, Kunal; Nezi, Luigi; Amin, Samir B; Wu, Chia-Chin; Akdemir, Kadir C; Mahdavi, Mozhdeh; Peng, Qian; Chang, Qing Edward; Hornigold, Kirsti; Arold, Stefan T; Welch, Heidi C E; Garraway, Levi A; Chin, Lynda

2016-03-01

PREX2 (phosphatidylinositol-3,4,5-triphosphate-dependent Rac-exchange factor 2) is a PTEN (phosphatase and tensin homolog deleted on chromosome 10) binding protein that is significantly mutated in cutaneous melanoma and pancreatic ductal adenocarcinoma. Here, genetic and biochemical analyses were conducted to elucidate the nature and mechanistic basis of PREX2 mutation in melanoma development. By generating an inducible transgenic mouse model we showed an oncogenic role for a truncating PREX2 mutation (PREX2(E824)*) in vivo in the context of mutant NRAS. Using integrative cross-species gene expression analysis, we identified deregulated cell cycle and cytoskeleton organization as significantly perturbed biological pathways in PREX2 mutant tumors. Mechanistically, truncation of PREX2 activated its Rac1 guanine nucleotide exchange factor activity, abolished binding to PTEN and activated the PI3K (phosphatidyl inositol 3 kinase)/Akt signaling pathway. We further showed that PREX2 truncating mutations or PTEN deletion induces down-regulation of the tumor suppressor and cell cycle regulator CDKN1C (also known as p57(KIP2)). This down-regulation occurs, at least partially, through DNA hypomethylation of a differentially methylated region in chromosome 11 that is a known regulatory region for expression of the CDKN1C gene. Together, these findings identify PREX2 as a mediator of NRAS-mutant melanoma development that acts through the PI3K/PTEN/Akt pathway to regulate gene expression of a cell cycle regulator.

Truncating PREX2 mutations activate its GEF activity and alter gene expression regulation in NRAS-mutant melanoma

KAUST Repository

Lissanu Deribe, Yonathan; Shi, Yanxia; Rai, Kunal; Nezi, Luigi; Amin, Samir B.; Wu, Chia-Chin; Akdemir, Kadir C.; Mahdavi, Mozhdeh; Peng, Qian; Chang, Qing Edward; Hornigold, Kirsti; Arold, Stefan T.; Welch, Heidi C. E.; Garraway, Levi A.; Chin, Lynda

2016-01-01

PREX2 (phosphatidylinositol-3,4,5-triphosphate-dependent Rac-exchange factor 2) is a PTEN (phosphatase and tensin homolog deleted on chromosome 10) binding protein that is significantly mutated in cutaneous melanoma and pancreatic ductal adenocarcinoma. Here, genetic and biochemical analyses were conducted to elucidate the nature and mechanistic basis of PREX2 mutation in melanoma development. By generating an inducible transgenic mouse model we showed an oncogenic role for a truncating PREX2 mutation (PREX2E824*) in vivo in the context of mutant NRAS. Using integrative cross-species gene expression analysis, we identified deregulated cell cycle and cytoskeleton organization as significantly perturbed biological pathways in PREX2 mutant tumors. Mechanistically, truncation of PREX2 activated its Rac1 guanine nucleotide exchange factor activity, abolished binding to PTEN and activated the PI3K (phosphatidyl inositol 3 kinase)/Akt signaling pathway. We further showed that PREX2 truncating mutations or PTEN deletion induces down-regulation of the tumor suppressor and cell cycle regulator CDKN1C (also known as p57KIP2). This down-regulation occurs, at least partially, through DNA hypomethylation of a differentially methylated region in chromosome 11 that is a known regulatory region for expression of the CDKN1C gene. Together, these findings identify PREX2 as a mediator of NRAS-mutant melanoma development that acts through the PI3K/PTEN/Akt pathway to regulate gene expression of a cell cycle regulator.

Ribosomal mutations promote the evolution of antibiotic resistance in a multidrug environment.

Science.gov (United States)

Gomez, James E; Kaufmann-Malaga, Benjamin B; Wivagg, Carl N; Kim, Peter B; Silvis, Melanie R; Renedo, Nikolai; Ioerger, Thomas R; Ahmad, Rushdy; Livny, Jonathan; Fishbein, Skye; Sacchettini, James C; Carr, Steven A; Hung, Deborah T

2017-02-21

Antibiotic resistance arising via chromosomal mutations is typically specific to a particular antibiotic or class of antibiotics. We have identified mutations in genes encoding ribosomal components in Mycobacterium smegmatis that confer resistance to several structurally and mechanistically unrelated classes of antibiotics and enhance survival following heat shock and membrane stress. These mutations affect ribosome assembly and cause large-scale transcriptomic and proteomic changes, including the downregulation of the catalase KatG, an activating enzyme required for isoniazid sensitivity, and upregulation of WhiB7, a transcription factor involved in innate antibiotic resistance. Importantly, while these ribosomal mutations have a fitness cost in antibiotic-free medium, in a multidrug environment they promote the evolution of high-level, target-based resistance. Further, suppressor mutations can then be easily acquired to restore wild-type growth. Thus, ribosomal mutations can serve as stepping-stones in an evolutionary path leading to the emergence of high-level, multidrug resistance.

Mutator suppression and escape from replication error-induced extinction in yeast.

Directory of Open Access Journals (Sweden)

Alan J Herr

2011-10-01

Full Text Available Cells rely on a network of conserved pathways to govern DNA replication fidelity. Loss of polymerase proofreading or mismatch repair elevates spontaneous mutation and facilitates cellular adaptation. However, double mutants are inviable, suggesting that extreme mutation rates exceed an error threshold. Here we combine alleles that affect DNA polymerase δ (Pol δ proofreading and mismatch repair to define the maximal error rate in haploid yeast and to characterize genetic suppressors of mutator phenotypes. We show that populations tolerate mutation rates 1,000-fold above wild-type levels but collapse when the rate exceeds 10⁻³ inactivating mutations per gene per cell division. Variants that escape this error-induced extinction (eex rapidly emerge from mutator clones. One-third of the escape mutants result from second-site changes in Pol δ that suppress the proofreading-deficient phenotype, while two-thirds are extragenic. The structural locations of the Pol δ changes suggest multiple antimutator mechanisms. Our studies reveal the transient nature of eukaryotic mutators and show that mutator phenotypes are readily suppressed by genetic adaptation. This has implications for the role of mutator phenotypes in cancer.

Cis-acting mutation and duplication: History of molecular evolution in a P450 haplotype responsible for insecticide resistance in Culex quinquefasciatus.

Science.gov (United States)

Itokawa, Kentaro; Komagata, Osamu; Kasai, Shinji; Masada, Masahiro; Tomita, Takashi

2011-07-01

A cytochrome P450 gene, Cyp9m10, is more than 200-fold overexpressed in a pyrethroid resistant strain of Culex quinquefasciatus, JPal-per. The haplotype of this strain contains two copies of Cyp9m10 resulted from recent tandem duplication. In this study, we discovered and isolated a Cyp9m10 haplotype closely related to this duplicated Cyp9m10 haplotype from JHB, a strain used for the recent genome project for this mosquito species. The isolated haplotype (JHB-NIID-B haplotype) shared the same insertion of a transposable element upstream of the coding region with JPal-per strain but not duplicated. The JHB-NIID-B haplotype was considered to have diverged from the JPal-per lineage just before the duplication event. Cyp9m10 was moderately overexpressed in larvae with the JHB-NIID-B haplotype. The overexpressions in JHB-NIID-B and JPal-per haplotypes were developmentally regulated in similar pattern indicating both haplotypes share a common cis-acting mutation responsible for the overexpressions. The isolated moderately overexpressed haplotype conferred resistance, however, its efficacy was relatively small. We hypothesized that the first cis-acting mutation modified the consequence of the subsequent duplication in JPal-per lineage to confer stronger phenotypic effect than that if it occurred before the first cis-acting mutation. Copyright © 2011 Elsevier Ltd. All rights reserved.

CENP-R acts bilaterally as a tumor suppressor and as an oncogene in the two-stage skin carcinogenesis model.

Science.gov (United States)

Okumura, Kazuhiro; Kagawa, Naoko; Saito, Megumi; Yoshizawa, Yasuhiro; Munakata, Haruka; Isogai, Eriko; Fukagawa, Tatsuo; Wakabayashi, Yuichi

2017-11-01

CENP-R is a component of the CENP-O complex, including CENP-O, CENP-P, CENP-Q, CENP-R, and CENP-U and is constitutively localized to kinetochores throughout the cell cycle in vertebrates. CENP-R-deficient chicken DT40 cells are viable and show a very minor effect on mitosis. To investigate the functional roles of CENP-R in vivo, we generated CENP-R-deficient mice (Cenp-r -/- ). Mice heterozygous or homozygous for Cenp-r null mutation are viable and healthy, with no apparent defect in growth and morphology, indicating Cenp-r is not essential for normal development. Accordingly, to investigate the role of the Cenp-r gene in skin carcinogenesis, we subjected Cenp-r -/- mice to the 7,12-dimethylbenz(a)anthracene (DMBA)/TPA chemical carcinogenesis protocol and monitored tumor development. As a result, Cenp-r -/- mice initially developed significantly more papillomas than control wild-type mice. However, papillomas in Cenp-r -/- mice showed a decrease of proliferative cells and an increase of apoptotic cells. As a result, they did not grow bigger and some papillomas showed substantial regression. Furthermore, papillomas in Cenp-r -/- mice showed lower frequency of malignant conversion to squamous cell carcinomas. These results indicate Cenp-r functions bilaterally in cancer development: during early developmental stages, Cenp-r functions as a tumor suppressor, but during the expansion and progression of papillomas it functions as a tumor-promoting factor. © 2017 The Authors. Cancer Science published by John Wiley & Sons Australia, Ltd on behalf of Japanese Cancer Association.

Somatic mutations in the transcriptional corepressor gene BCORL1 in adult acute myelogenous leukemia.

Science.gov (United States)

Li, Meng; Collins, Roxane; Jiao, Yuchen; Ouillette, Peter; Bixby, Dale; Erba, Harry; Vogelstein, Bert; Kinzler, Kenneth W; Papadopoulos, Nickolas; Malek, Sami N

2011-11-24

To further our understanding of the genetic basis of acute myelogenous leukemia (AML), we determined the coding exon sequences of ∼ 18 000 protein-encoding genes in 8 patients with secondary AML. Here we report the discovery of novel somatic mutations in the transcriptional corepressor gene BCORL1 that is located on the X-chromosome. Analysis of BCORL1 in an unselected cohort of 173 AML patients identified a total of 10 mutated cases (6%) with BCORL1 mutations, whereas analysis of 19 AML cell lines uncovered 4 (21%) BCORL1 mutated cell lines. The majority (87%) of the mutations in BCORL1 were predicted to inactivate the gene product as a result of nonsense mutations, splice site mutation, or out-of-frame insertions or deletions. These results indicate that BCORL1 by genetic criteria is a novel candidate tumor suppressor gene, joining the growing list of genes recurrently mutated in AML.

Presymptomatic breast cancer in Egypt: role of BRCA1 and BRCA2 tumor suppressor genes mutations detection

Directory of Open Access Journals (Sweden)

Hashishe Mervat M

2010-06-01

Full Text Available Abstract Background Breast cancer is one of the most common diseases affecting women. Inherited susceptibility genes, BRCA1 and BRCA2, are considered in breast, ovarian and other common cancers etiology. BRCA1 and BRCA2 genes have been identified that confer a high degree of breast cancer risk. Objective Our study was performed to identify germline mutations in some exons of BRCA1 and BRCA2 genes for the early detection of presymptomatic breast cancer in females. Methods This study was applied on Egyptian healthy females who first degree relatives to those, with or without a family history, infected with breast cancer. Sixty breast cancer patients, derived from 60 families, were selected for molecular genetic testing of BRCA1 and BRCA2 genes. The study also included 120 healthy first degree female relatives of the patients, either sisters and/or daughters, for early detection of presymptomatic breast cancer mutation carriers. Genomic DNA was extracted from peripheral blood lymphocytes of all the studied subjects. Universal primers were used to amplify four regions of the BRCA1 gene (exons 2,8,13 and 22 and one region (exon 9 of BRCA2 gene using specific PCR. The polymerase chain reaction was carried out. Single strand conformation polymorphism assay and heteroduplex analysis were used to screen for mutations in the studied exons. In addition, DNA sequencing of the normal and mutated exons were performed. Results Mutations in both BRCA1 and BRCA2 genes were detected in 86.7% of the families. Current study indicates that 60% of these families were attributable to BRCA1 mutations, while 26.7% of them were attributable to BRCA2 mutations. Results showed that four mutations were detected in the BRCA1 gene, while one mutation was detected in the BRCA2 gene. Asymptomatic relatives, 80(67% out of total 120, were mutation carriers. Conclusions BRCA1 and BRCA2 genes mutations are responsible for a significant proportion of breast cancer. BRCA mutations

Molecular Analysis: Microsatellite Instability and Loss of Heterozygosity of Tumor Suppressor Gene in Hereditary Non-Polyposis Colorectal Cancer (HNPCC

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Vesna Hadžiavdić

2009-02-01

Full Text Available HNPCC (Hereditary non-polyposis colorectal cancer development is caused by mutation of genes included in system of mismatch repair genes. The mutation exists at 60% of patients in hMSH2 gene, 30% in hMLH1 and 10% both in hPMS1and hPMS2 genes. RER+ exists in about 90% in hereditary non-polyposis colorectal cancer and about 15-28% in sporadic cancers.The purpose of the study was to determine highly sensitive microsatellite markers which can be fast and efficient way of microsatellite screening for detection of HNPCC patients. Moreover, we have analysed the loss of heterozygosity of tumour suppressor genes which could have the diagnostic value in detection of HPNCC patients.

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.

Syk Tyrosine Kinase Acts as a Pancreatic Adenocarcinoma Tumor Suppressor by Regulating Cellular Growth and Invasion

OpenAIRE

Layton, Tracy; Stalens, Cristel; Gunderson, Felizza; Goodison, Steve; Silletti, Steve

2009-01-01

We have identified the nonreceptor tyrosine kinase syk as a marker of differentiation/tumor suppressor in pancreatic ductal adenocarcinoma (PDAC). Syk expression is lost in poorly differentiated PDAC cells in vitro and in situ, and stable reexpression of syk in endogenously syk-negative Panc1 (Panc1/syk) cells retarded their growth in vitro and in vivo and reduced anchorage-independent growth in vitro. Panc1/syk cells exhibited a more differentiated morphology and down-regulated cyclin D1, ak...

A viral suppressor of RNA silencing inhibits ARGONAUTE 1 function by precluding target RNA binding to pre-assembled RISC.

Science.gov (United States)

Kenesi, Erzsébet; Carbonell, Alberto; Lózsa, Rita; Vértessy, Beáta; Lakatos, Lóránt

2017-07-27

In most eukaryotes, RNA silencing is an adaptive immune system regulating key biological processes including antiviral defense. To evade this response, viruses of plants, worms and insects have evolved viral suppressors of RNA silencing proteins (VSRs). Various VSRs, such as P1 from Sweet potato mild mottle virus (SPMMV), inhibit the activity of RNA-induced silencing complexes (RISCs) including an ARGONAUTE (AGO) protein loaded with a small RNA. However, the specific mechanisms explaining this class of inhibition are unknown. Here, we show that SPMMV P1 interacts with AGO1 and AGO2 from Arabidopsis thaliana, but solely interferes with AGO1 function. Moreover, a mutational analysis of a newly identified zinc finger domain in P1 revealed that this domain could represent an effector domain as it is required for P1 suppressor activity but not for AGO1 binding. Finally, a comparative analysis of the target RNA binding capacity of AGO1 in the presence of wild-type or suppressor-defective P1 forms revealed that P1 blocks target RNA binding to AGO1. Our results describe the negative regulation of RISC, the small RNA containing molecular machine. © The Author(s) 2017. Published by Oxford University Press on behalf of Nucleic Acids Research.

Two co-existing germline mutations P53 V157D and PMS2 R20Q promote tumorigenesis in a familial cancer syndrome.

Science.gov (United States)

Wang, Zuoyun; Sun, Yihua; Gao, Bin; Lu, Yi; Fang, Rong; Gao, Yijun; Xiao, Tian; Liu, Xin-Yuan; Pao, William; Zhao, Yun; Chen, Haiquan; Ji, Hongbin

2014-01-01

Germline mutations are responsible for familial cancer syndromes which account for approximately 5-10% of all types of cancers. These mutations mainly occur at tumor suppressor genes or genome stability genes, such as DNA repair genes. Here we have identified a cancer predisposition family, in which eight members were inflicted with a wide spectrum of cancer including one diagnosed with lung cancer at 22years old. Sequencing analysis of tumor samples as well as histologically normal specimens identified two germline mutations co-existing in the familial cancer syndrome, the mutation of tumor suppressor gene P53 V157D and mismatch repair gene PMS2 R20Q. We further demonstrate that P53 V157D and/or PMS2 R20Q mutant promotes lung cancer cell proliferation. These two mutants are capable of promoting colony formation in soft agar as well as tumor formation in transgenic drosophila system. Collectively, these data have uncovered the important role of co-existing germline P53 and PMS2 mutations in the familial cancer syndrome development. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

Somatic mutations affect key pathways in lung adenocarcinoma

Science.gov (United States)

Ding, Li; Getz, Gad; Wheeler, David A.; Mardis, Elaine R.; McLellan, Michael D.; Cibulskis, Kristian; Sougnez, Carrie; Greulich, Heidi; Muzny, Donna M.; Morgan, Margaret B.; Fulton, Lucinda; Fulton, Robert S.; Zhang, Qunyuan; Wendl, Michael C.; Lawrence, Michael S.; Larson, David E.; Chen, Ken; Dooling, David J.; Sabo, Aniko; Hawes, Alicia C.; Shen, Hua; Jhangiani, Shalini N.; Lewis, Lora R.; Hall, Otis; Zhu, Yiming; Mathew, Tittu; Ren, Yanru; Yao, Jiqiang; Scherer, Steven E.; Clerc, Kerstin; Metcalf, Ginger A.; Ng, Brian; Milosavljevic, Aleksandar; Gonzalez-Garay, Manuel L.; Osborne, John R.; Meyer, Rick; Shi, Xiaoqi; Tang, Yuzhu; Koboldt, Daniel C.; Lin, Ling; Abbott, Rachel; Miner, Tracie L.; Pohl, Craig; Fewell, Ginger; Haipek, Carrie; Schmidt, Heather; Dunford-Shore, Brian H.; Kraja, Aldi; Crosby, Seth D.; Sawyer, Christopher S.; Vickery, Tammi; Sander, Sacha; Robinson, Jody; Winckler, Wendy; Baldwin, Jennifer; Chirieac, Lucian R.; Dutt, Amit; Fennell, Tim; Hanna, Megan; Johnson, Bruce E.; Onofrio, Robert C.; Thomas, Roman K.; Tonon, Giovanni; Weir, Barbara A.; Zhao, Xiaojun; Ziaugra, Liuda; Zody, Michael C.; Giordano, Thomas; Orringer, Mark B.; Roth, Jack A.; Spitz, Margaret R.; Wistuba, Ignacio I.; Ozenberger, Bradley; Good, Peter J.; Chang, Andrew C.; Beer, David G.; Watson, Mark A.; Ladanyi, Marc; Broderick, Stephen; Yoshizawa, Akihiko; Travis, William D.; Pao, William; Province, Michael A.; Weinstock, George M.; Varmus, Harold E.; Gabriel, Stacey B.; Lander, Eric S.; Gibbs, Richard A.; Meyerson, Matthew; Wilson, Richard K.

2009-01-01

Determining the genetic basis of cancer requires comprehensive analyses of large collections of histopathologically well-classified primary tumours. Here we report the results of a collaborative study to discover somatic mutations in 188 human lung adenocarcinomas. DNA sequencing of 623 genes with known or potential relationships to cancer revealed more than 1,000 somatic mutations across the samples. Our analysis identified 26 genes that are mutated at significantly high frequencies and thus are probably involved in carcinogenesis. The frequently mutated genes include tyrosine kinases, among them the EGFR homologue ERBB4; multiple ephrin receptor genes, notably EPHA3; vascular endothelial growth factor receptor KDR; and NTRK genes. These data provide evidence of somatic mutations in primary lung adenocarcinoma for several tumour suppressor genes involved in other cancers—including NF1, APC, RB1 and ATM—and for sequence changes in PTPRD as well as the frequently deleted gene LRP1B. The observed mutational profiles correlate with clinical features, smoking status and DNA repair defects. These results are reinforced by data integration including single nucleotide polymorphism array and gene expression array. Our findings shed further light on several important signalling pathways involved in lung adenocarcinoma, and suggest new molecular targets for treatment. PMID:18948947

Identification and Characterization of Genes That Interact with Lin-12 in Caenorhabditis Elegans

OpenAIRE

Tax, F. E.; Thomas, J. H.; Ferguson, E. L.; Horvitz, H. R.

1997-01-01

We identified and characterized 14 extragenic mutations that suppressed the dominant egg-laying defect of certain lin-12 gain-of-function mutations. These suppressors defined seven genes: sup-17, lag-2, sel-4, sel-5, sel-6, sel-7 and sel-8. Mutations in six of the genes are recessive suppressors, whereas the two mutations that define the seventh gene, lag-2, are semi-dominant suppressors. These suppressor mutations were able to suppress other lin-12 gain-of-function mutations. The suppressor ...

Association of the germline TP53 R337H mutation with breast cancer in southern Brazil

Directory of Open Access Journals (Sweden)

Srivastava Kumar

2008-12-01

Full Text Available Abstract Background The germline TP53-R337H mutation is strongly associated with pediatric adrenocortical tumors (ACT in southern Brazil; it has low penetrance and limited tissue specificity in most families and therefore is not associated with Li-Fraumeni syndrome. However, other tumor types, mainly breast cancer, have been observed in carriers of several unrelated kindreds, raising the possibility that the R337H mutation may also contribute to breast tumorigenesis in a genetic background-specific context. Methods We conducted a case-control study to determine the prevalence of the R337H mutation by sequencing TP53 exon 10 in 123 women with breast cancer and 223 age- and sex-matched control subjects from southern Brazil. Fisher's test was used to compare the prevalence of the R337H. Results The R337H mutation was found in three patients but in none of the controls (p = 0.0442. Among the carriers, two had familial history of cancer meeting the Li-Fraumeni-like criteria. Remarkably, tumors in each of these three cases underwent loss of heterozygosity by eliminating the mutant TP53 allele rather than the wild-type allele. Polymorphisms were identified within the TP53 (R72P and Ins16 and MDM2 (SNP309 genes that may further diminish TP53 tumor suppressor activity. Conclusion These results demonstrate that the R337H mutation can significantly increase the risk of breast cancer in carriers, which likely depends on additional cooperating genetic factors. These findings are also important for understanding how low-penetrant mutant TP53 alleles can differentially influence tumor susceptibility.

Focusing on function to mine cancer genome data | Center for Cancer Research

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CCR scientists have devised a strategy to sift through the tens of thousands of mutations in cancer genome data to find mutations that actually drive the disease. They have used the method to discover that the JNK signaling pathway, which in different contexts can either spur cancerous growth or rein it in, acts as a tumor suppressor in gastric cancers. 

Trefoil factor 3 is required for differentiation of thyroid follicular cells and acts as a context-dependent tumor suppressor.

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Abols, A; Ducena, K; Andrejeva, D; Sadovska, L; Zandberga, E; Vilmanis, J; Narbuts, Z; Tars, J; Eglitis, J; Pirags, V; Line, A

2015-01-01

Trefoil factor 3 (TFF3) is overexpressed in a variety of solid epithelial cancers, where it has been shown to promote migration, invasion, proliferation, survival and angiogenesis. On the contrary, in the majority of thyroid tumors, it is downregulated, yet its role in the development of thyroid cancer remains unknown. Here we show that TFF3 exhibits strong cytoplasmic staining of normal thyroid follicular cells and colloid and the staining is increased in hyperfunctioning thyroid nodules, while it is decreased in all thyroid cancers of follicular cell origin. By meta-analysis of gene expression datasets, we found that in the thyroid cancer, conversely to the breast cancer, the expression of TFF3 mRNA was downregulated by estrogen signaling and confirmed this by treating thyroid cancer cells with estradiol. Forced expression of TFF3 in anaplastic thyroid cancer cells resulted in decreased cell proliferation, clonal spheroid formation and entry into the S phase. Furthermore, it induced acquisition of epithelial-like cell morphology and expression of the differentiation markers of thyroid follicular cells and transcription factors implicated in the thyroid morphogenesis and function. Taken together, this study provides the first evidence that TFF3 may act as a tumor suppressor or an oncogene depending on the cellular context.

The tumor suppressor gene TRC8/RNF139 is disrupted by a constitutional balanced translocation t(8;22(q24.13;q11.21 in a young girl with dysgerminoma

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Fiorio Patrizia

2009-07-01

Full Text Available Abstract Background RNF139/TRC8 is a potential tumor suppressor gene with similarity to PTCH, a tumor suppressor implicated in basal cell carcinomas and glioblastomas. TRC8 has the potential to act in a novel regulatory relationship linking the cholesterol/lipid biosynthetic pathway with cellular growth control and has been identified in families with hereditary renal (RCC and thyroid cancers. Haploinsufficiency of TRC8 may facilitate development of clear cell-RCC in association with VHL mutations, and may increase risk for other tumor types. We report a paternally inherited balanced translocation t(8;22 in a proposita with dysgerminoma. Methods The translocation was characterized by FISH and the breakpoints cloned, sequenced, and compared. DNA isolated from normal and tumor cells was checked for abnormalities by array-CGH. Expression of genes TRC8 and TSN was tested both on dysgerminoma and in the proposita and her father. Results The breakpoints of the translocation are located within the LCR-B low copy repeat on chromosome 22q11.21, containing the palindromic AT-rich repeat (PATRR involved in recurrent and non-recurrent translocations, and in an AT-rich sequence inside intron 1 of the TRC8 tumor-suppressor gene at 8q24.13. TRC8 was strongly underexpressed in the dysgerminoma. Translin is underexpressed in the dysgerminoma compared to normal ovary. TRC8 is a target of Translin (TSN, a posttranscriptional regulator of genes transcribed by the transcription factor CREM-tau in postmeiotic male germ cells. Conclusion A role for TRC8 in dysgerminoma may relate to its interaction with Translin. We propose a model in which one copy of TRC8 is disrupted by a palindrome-mediated translocation followed by complete loss of expression through suppression, possibly mediated by miRNA.

Mechanisms of cross-suppression of TNP-specific plaque forming cell responses by TMA-specific first-order T suppressor factor

Energy Technology Data Exchange (ETDEWEB)

Jendrisak, G.S.; Bellone, C.J.

1986-03-05

The addition of hybridoma-derived phenyltrimethylammonium (TMA)-specific first-order T suppressor factor (TsF/sub 1/) into cultures containing Brucella abortus coupled with the TMA and trinitrophenol haptens (TMA-BA-TNP) results in the cross-suppression of TNP-specific plaque forming cell (PFC) responses. The suppression mediated by TMA-TsF/sub 1/ is dependent on the presence of T cells and specific antigen (TMA). Subculturing of whole spleen cells with TMA-TsF/sub 1/ and specific soluble antigen (TMA-BSA) is able to induce suppressor T cells which cross-suppress the TNP-specific PFC of spleen cell cultures stimulated with TMA-BA-TNP in an antigen (TMA)-dependent manner at the effector phase of the response. The effector acting T suppressor cells (Tse) are nylon wool nonadherent and appears to require whole spleen cells in responding cultures for suppression, suggesting that the target of the Tse is not the TNP-specific B cell. The authors are presently characterizing the mechanisms of cross-suppression by TMA-TsF/sub 1/ and Tse utilizing the described primary in vitro antibody assay.

Mutator activity in Schizophyllum commune

Energy Technology Data Exchange (ETDEWEB)

Shneyour, Y.; Koltin, Y. (Tel Aviv Univ. (Israel). Dept. of Microbiology)

1983-01-01

A strain with an elevated level of spontaneous mutations and an especially high rate of reversion at a specific locus (pab/sup -/) was identified. The mutator trait is recessive. UV sensitivity and the absence of a UV-specific endonucleolytic activity were associated with the enhancement of the mutation rate in mutator strains. The endonuclease associated with the regulation of the mutation rate also acted on single-stranded DNA. The molecular weight of this enzyme is about 38,000 daltons.

Mutation analysis of breast cancer gene BRCA among breast cancer Jordanian females

International Nuclear Information System (INIS)

Atoum, Manar F.; Al-Kayed, Sameer A.

2004-01-01

To screen mutations of the tumor suppressor breast cancer susceptibility gene 1 (BRCA1) within 3 exons among Jordanian breast cancer females. A total of 135 Jordanian breast cancer females were genetically analyzed by denaturing gradient electrophoresis (DGGE) for mutation detection in 3 BRCA1 exons (2, 11 and 20) between 2000-2002 in Al-Basheer Hospital, Amman, Jordan. Of the studied patients 50 had a family history of breast cancer, 28 had a family history of cancer other than breast cancer, and 57 had no family history of any cancer. Five germline mutations were detected among breast cancer females with a family history of breast cancers (one in exon 2 and 4 mutations in exon 11). Another germline mutation (within exon 11) was detected among breast cancer females with family history of cancer other than breast cancer, and no mutation was detected among breast cancer females with no family history of any cancer or among normal control females. Screening mutations within exon 2, exon 11 and exon 20 showed that most screened mutations were within BRCA1 exon 11 among breast cancer Jordanian families with a family history of breast cancer. (author)

LncRNA TUG1 acts as a tumor suppressor in human glioma by promoting cell apoptosis.

Science.gov (United States)

Li, Jun; Zhang, Meng; An, Gang; Ma, Qingfang

2016-03-01

Previous studies have revealed multiple functional roles of long non-coding RNA taurine upregulated gene 1 in different types of malignant tumors, except for human glioma. Here, it was designed to study the potential function of taurine upregulated gene 1 in glioma pathogenesis focusing on its regulation on cell apoptosis. The expression of taurine upregulated gene 1 in glioma tissues was detected by quantitative RT-PCR and compared with that in adjacent normal tissues. Further correlation analysis was conducted to show the relationship between taurine upregulated gene 1 expression and different clinicopathologic parameters. Functional studies were performed to investigate the influence of taurine upregulated gene 1 on apoptosis and cell proliferation by using Annexin V/PI staining and cell counting kit-8 assays, respectively. And, caspase activation and Bcl-2 expression were analyzed to explore taurine upregulated gene 1-induced mechanism. taurine upregulated gene 1 expression was significantly inhibited in glioma and showed significant correlation with WHO Grade, tumor size and overall survival. Further experiments revealed that the dysregulation of taurine upregulated gene 1 affected the apoptosis and cell proliferation of glioma cells. Moreover, taurine upregulated gene 1 could induce the activation of caspase-3 and-9, with inhibited expression of Bcl-2, implying the mechanism in taurine upregulated gene 1-induced apoptosis. taurine upregulated gene 1 promoted cell apoptosis of glioma cells by activating caspase-3 and -9-mediated intrinsic pathways and inhibiting Bcl-2-mediated anti-apoptotic pathways, acting as a tumor suppressor in human glioma. This study provided new insights for the function of taurine upregulated gene 1 in cancer biology, and suggested a potent application of taurine upregulated gene 1 overexpression for glioma therapy. © 2016 by the Society for Experimental Biology and Medicine.

Peroxisome proliferator-activated receptor gamma coactivator-1 alpha acts as a tumor suppressor in hepatocellular carcinoma.

Science.gov (United States)

Liu, Rui; Zhang, Haiyang; Zhang, Yan; Li, Shuang; Wang, Xinyi; Wang, Xia; Wang, Cheng; Liu, Bin; Zen, Ke; Zhang, Chen-Yu; Zhang, Chunni; Ba, Yi

2017-04-01

Peroxisome proliferator-activated receptor gamma coactivator-1 alpha plays a crucial role in regulating the biosynthesis of mitochondria, which is closely linked to the energy metabolism in various tumors. This study investigated the regulatory role of peroxisome proliferator-activated receptor gamma coactivator-1 alpha in the pathogenesis of hepatocellular carcinoma. In this study, the changes of peroxisome proliferator-activated receptor gamma coactivator-1 alpha messenger RNA levels between normal human liver and hepatocellular carcinoma tissue were examined by quantitative reverse transcription polymerase chain reaction. Knockdown of peroxisome proliferator-activated receptor gamma coactivator-1 alpha was conducted by RNA interference in the human liver cell line L02, while overexpression of peroxisome proliferator-activated receptor gamma coactivator-1 alpha was conducted by adenovirus encoding peroxisome proliferator-activated receptor gamma coactivator-1 alpha complementary DNA in the human hepatocarcinoma cell line HepG2. Cellular morphological changes were observed via optical and electron microscopy. Cellular apoptosis was determined by Hoechst 33258 staining. In addition, the expression levels of 21,400 genes in tissues and cells were detected by microarray. It was shown that peroxisome proliferator-activated receptor gamma coactivator-1 alpha expression was significantly downregulated in hepatocellular carcinoma compared with normal liver tissues. After knockdown of peroxisome proliferator-activated receptor gamma coactivator-1 alpha expression in L02 cells, cells reverted to immature and dedifferentiated morphology exhibiting cancerous tendency. Apoptosis occurred in the HepG2 cells after transfection by adenovirus encoding peroxisome proliferator-activated receptor gamma coactivator-1 alpha. Microarray analysis showed consistent results. The results suggest that peroxisome proliferator-activated receptor gamma coactivator-1 alpha acts as a tumor

Control of polyclonal immunoglobulin production from human lymphocytes by leukotrienes; leukotriene B4 induces an OKT8(+), radiosensitive suppressor cell from resting, human OKT8(-) T cells

International Nuclear Information System (INIS)

Atluru, D.; Goodwin, J.S.

1984-01-01

We report that leukotriene B4 (LTB4), a 5-lipoxygenase metabolite of arachidonic acid, is a potent suppressor of polyclonal Ig production in pokeweed mitogen (PWM)-stimulated cultures of human peripheral blood lymphocytes, while LTC4 and LTD4 have little activity in this system. Preincubation of T cells with LTB4 in nanomolar to picomolar concentrations rendered these cells suppressive of Ig production in subsequent PWM-stimulated cultures of fresh, autologous B + T cells. This LTB4-induced suppressor cell was radiosensitive, and its generation could be blocked by cyclohexamide but not by mitomycin C. The LTB4-induced suppressor cell was OKT8(+), while the precursor for the cell could be OKT8(-). The incubation of OKT8(-) T cells with LTB4 for 18 h resulted in the appearance of the OKT8(+) on 10-20% of the cells, and this could be blocked by cyclohexamide but not by mitomycin C. Thus, LTB4 in very low concentrations induces a radiosensitive OKT8(+) suppressor cell from OKT8(-) cells. In this regard, LTB4 is three to six orders of magnitude more potent than any endogenous hormonal inducer of suppressor cells previously described. Glucocorticosteroids, which block suppressor cell induction in many systems, may act by inhibiting endogenous production of LTB4

[CDC73 mutations in young patients with primary hyperparathyroidism: A description of two clinical cases].

Science.gov (United States)

Mamedova, E O; Mokrysheva, N G; Pigarova, E A; Przhiyalkovskaya, E G; Voronkova, I A; Vasilyev, E V; Petrov, V M; Gorbunova, V A; Rozhinskaya, L Ya; Belaya, Zh E; Tyulpakov, A N

The article describes two clinical cases of severe primary hyperparathyroidism (PHPT) caused by parathyroid carcinoma in young female patients who underwent molecular genetic testing to rule out the hereditary forms of PHPT. In both patients, heterozygous germline nonsense mutations of tumor suppressor gene CDC73 encoding parafibromin (p.R91X and p.Q166X) were identified using next-generation sequencing with Ion Torrent Personal Genome Machine (Thermo Fisher Scientific - Life Technologies, USA). It is the first description of CDC73 mutations in Russia, one of the mutations is described for the first time in the world. Identification of germline mutations in the CDC73 gene in patients with PHPT necessitates regular lifelong screening for other manifestations of hyperparathyroidism-jaw tumor syndrome (HPT-JT), PHPT recurrence due to parathyroid carcinoma as well, and identification of mutation carriers among first-degree relatives.

The prognostic value of p53 mutation in pediatric marrow hypoplasia

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Sharaf Alzahraa EA

2011-06-01

Full Text Available Abstract Background The tumor suppressor gene p53 is involved in the control of cell proliferation, particularly in stressed cells. p 53 gene mutations are the most frequent genetic event found in human cancers. Fanconi Anemia (FA is the most common representative of inherited bone marrow failure syndromes (IBMFS with a leukemic propensity. P 53 DNA alteration has not been studied before in Egyptian children with FA. Patients and methods we investigated p53 mutation in the bone marrow and peripheral blood of forty children, FA (n = 10, acquired aplastic anemia (AAA (n = 10, and immune thrombocytopenia (ITP as a control (n = 20, using real-time PCR by TaqMan probe assay Results Mutation of p53 gene was demonstrated in the BM of 90% (9/10 of children with FA, compared to 10% (1/10 in AAA (p Conclusion mutation of p53 gene in hypoplastic marrow especially FA may represent an early indicator of significant DNA genetic alteration with cancer propensity.

Metabolic engineering of an ATP-neutral Embden-Meyerhof-Parnas pathway in Corynebacterium glutamicum: growth restoration by an adaptive point mutation in NADH dehydrogenase.

Science.gov (United States)

Komati Reddy, Gajendar; Lindner, Steffen N; Wendisch, Volker F

2015-03-01

Corynebacterium glutamicum uses the Embden-Meyerhof-Parnas pathway of glycolysis and gains 2 mol of ATP per mol of glucose by substrate-level phosphorylation (SLP). To engineer glycolysis without net ATP formation by SLP, endogenous phosphorylating NAD-dependent glyceraldehyde-3-phosphate dehydrogenase (GAPDH) was replaced by nonphosphorylating NADP-dependent glyceraldehyde-3-phosphate dehydrogenase (GapN) from Clostridium acetobutylicum, which irreversibly converts glyceraldehyde-3-phosphate (GAP) to 3-phosphoglycerate (3-PG) without generating ATP. As shown recently (S. Takeno, R. Murata, R. Kobayashi, S. Mitsuhashi, and M. Ikeda, Appl Environ Microbiol 76:7154-7160, 2010, http://dx.doi.org/10.1128/AEM.01464-10), this ATP-neutral, NADPH-generating glycolytic pathway did not allow for the growth of Corynebacterium glutamicum with glucose as the sole carbon source unless hitherto unknown suppressor mutations occurred; however, these mutations were not disclosed. In the present study, a suppressor mutation was identified, and it was shown that heterologous expression of udhA encoding soluble transhydrogenase from Escherichia coli partly restored growth, suggesting that growth was inhibited by NADPH accumulation. Moreover, genome sequence analysis of second-site suppressor mutants that were able to grow faster with glucose revealed a single point mutation in the gene of non-proton-pumping NADH:ubiquinone oxidoreductase (NDH-II) leading to the amino acid change D213G, which was shared by these suppressor mutants. Since related NDH-II enzymes accepting NADPH as the substrate possess asparagine or glutamine residues at this position, D213G, D213N, and D213Q variants of C. glutamicum NDH-II were constructed and were shown to oxidize NADPH in addition to NADH. Taking these findings together, ATP-neutral glycolysis by the replacement of endogenous NAD-dependent GAPDH with NADP-dependent GapN became possible via oxidation of NADPH formed in this pathway by mutant NADPH

Inactivation and inducible oncogenic mutation of p53 in gene targeted pigs.

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Simon Leuchs

Full Text Available Mutation of the tumor suppressor p53 plays a major role in human carcinogenesis. Here we describe gene-targeted porcine mesenchymal stem cells (MSCs and live pigs carrying a latent TP53(R167H mutant allele, orthologous to oncogenic human mutant TP53(R175H and mouse Trp53(R172H, that can be activated by Cre recombination. MSCs carrying the latent TP53(R167H mutant allele were analyzed in vitro. Homozygous cells were p53 deficient, and on continued culture exhibited more rapid proliferation, anchorage independent growth, and resistance to the apoptosis-inducing chemotherapeutic drug doxorubicin, all characteristic of cellular transformation. Cre mediated recombination activated the latent TP53(R167H allele as predicted, and in homozygous cells expressed mutant p53-R167H protein at a level ten-fold greater than wild-type MSCs, consistent with the elevated levels found in human cancer cells. Gene targeted MSCs were used for nuclear transfer and fifteen viable piglets were produced carrying the latent TP53(R167H mutant allele in heterozygous form. These animals will allow study of p53 deficiency and expression of mutant p53-R167H to model human germline, or spontaneous somatic p53 mutation. This work represents the first inactivation and mutation of the gatekeeper tumor suppressor gene TP53 in a non-rodent mammal.

Suppressor of cytokine signaling 1 interacts with oncogenic lymphocyte-specific protein tyrosine kinase.

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Venkitachalam, Srividya; Chueh, Fu-Yu; Leong, King-Fu; Pabich, Samantha; Yu, Chao-Lan

2011-03-01

Lymphocyte-specific protein tyrosine kinase (Lck) plays a key role in T cell signal transduction and is tightly regulated by phosphorylation and dephosphorylation. Lck can function as an oncoprotein when overexpressed or constantly activated by mutations. Our previous studies showed that Lck-induced cellular transformation could be suppressed by enforced expression of suppressor of cytokine signaling 1 (SOCS1), a SOCS family member involved in the negative feedback control of cytokine signaling. We observed attenuated Lck kinase activity in SOCS1-expressing cells, suggesting an important role of SOCS in regulating Lck functions. It remains largely unknown whether and how SOCS proteins interact with the oncogenic Lck kinase. Here, we report that among four SOCS family proteins, SOCS1, SOCS2, SOCS3 and CIS (cytokine-inducible SH2 domain containing protein), SOCS1 has the highest affinity in binding to the oncogenic Lck kinase. We identified the positive regulatory phosphotyrosine 394 residue in the kinase domain as the key interacting determinant in Lck. Additionally, the Lck kinase domain alone is sufficient to bind SOCS1. While the SH2 domain in SOCS1 is important in its association with the oncogenic Lck kinase, other functional domains may also contribute to overall binding affinity. These findings provide important mechanistic insights into the role of SOCS proteins as tumor suppressors in cells transformed by oncogenic protein tyrosine kinases.

Screening of 1331 Danish breast and/or ovarian cancer families identified 40 novel BRCA1 and BRCA2 mutations

DEFF Research Database (Denmark)

Hansen, Thomas V O; Jønson, Lars; Steffensen, Ane Y

2011-01-01

Germ-line mutations in the tumour suppressor genes BRCA1 and BRCA2 predispose to breast and ovarian cancer. Since 1999 we have performed mutational screening of breast and/or ovarian cancer patients in East Denmark. During this period we have identified 40 novel sequence variations in BRCA1...... and BRCA2 in high risk breast and/or ovarian cancer families. The mutations were detected via pre-screening using dHPLC or high-resolution melting and direct sequencing. We identified 16 variants in BRCA1, including 9 deleterious frame-shift mutations, 2 intronic variants, 4 missense mutations, and 1......, the presumed significance of the missense mutations was predicted in silico using the align GVGD algorithm. In conclusion, the mutation screening identified 40 novel variants in the BRCA1 and BRCA2 genes and thereby extends the knowledge of the BRCA1/BRCA2 mutation spectrum. Nineteen of the mutations were...

Somatic mutations in histiocytic sarcoma identified by next generation sequencing.

Science.gov (United States)

Liu, Qingqing; Tomaszewicz, Keith; Hutchinson, Lloyd; Hornick, Jason L; Woda, Bruce; Yu, Hongbo

2016-08-01

Histiocytic sarcoma is a rare malignant neoplasm of presumed hematopoietic origin showing morphologic and immunophenotypic evidence of histiocytic differentiation. Somatic mutation importance in the pathogenesis or disease progression of histiocytic sarcoma was largely unknown. To identify somatic mutations in histiocytic sarcoma, we studied 5 histiocytic sarcomas [3 female and 2 male patients; mean age 54.8 (20-72), anatomic sites include lymph node, uterus, and pleura] and matched normal tissues from each patient as germ line controls. Somatic mutations in 50 "Hotspot" oncogenes and tumor suppressor genes were examined using next generation sequencing. Three (out of five) histiocytic sarcoma cases carried somatic mutations in BRAF. Among them, G464V [variant frequency (VF) of 43.6 %] and G466R (VF of 29.6 %) located at the P loop potentially interfere with the hydrophobic interaction between P and activating loops and ultimately activation of BRAF. Also detected was BRAF somatic mutation N581S (VF of 7.4 %), which was located at the catalytic loop of BRAF kinase domain: its role in modifying kinase activity was unclear. A similar mutational analysis was also performed on nine acute monocytic/monoblastic leukemia cases, which did not identify any BRAF somatic mutations. Our study detected several BRAF mutations in histiocytic sarcomas, which may be important in understanding the tumorigenesis of this rare neoplasm and providing mechanisms for potential therapeutical opportunities.

Towards the Identification of New Genes Involved in ABA-Dependent Abiotic Stresses Using Arabidopsis Suppressor Mutants of abh1 Hypersensitivity to ABA during Seed Germination

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Iwona Szarejko

2013-06-01

Full Text Available Abscisic acid plays a pivotal role in the abiotic stress response in plants. Although great progress has been achieved explaining the complexity of the stress and ABA signaling cascade, there are still many questions to answer. Mutants are a valuable tool in the identification of new genes or new alleles of already known genes and in elucidating their role in signaling pathways. We applied a suppressor mutation approach in order to find new components of ABA and abiotic stress signaling in Arabidopsis. Using the abh1 (ABA hypersensitive 1 insertional mutant as a parental line for EMS mutagenesis, we selected several mutants with suppressed hypersensitivity to ABA during seed germination. Here, we present the response to ABA and a wide range of abiotic stresses during the seed germination and young seedling development of two suppressor mutants—soa2 (suppressor of abh1 hypersensitivity to ABA 2 and soa3 (suppressor of abh1 hypersensitivity to ABA 3. Generally, both mutants displayed a suppression of the hypersensitivity of abh1 to ABA, NaCl and mannitol during germination. Both mutants showed a higher level of tolerance than Columbia-0 (Col-0—the parental line of abh1 in high concentrations of glucose. Additionally, soa2 exhibited better root growth than Col-0 in the presence of high ABA concentrations. soa2 and soa3 were drought tolerant and both had about 50% fewer stomata per mm2 than the wild-type but the same number as their parental line—abh1. Taking into account that suppressor mutants had the same genetic background as their parental line—abh1, it was necessary to backcross abh1 with Landsberg erecta four times for the map-based cloning approach. Mapping populations, derived from the cross of abh1 in the Landsberg erecta background with each suppressor mutant, were created. Map based cloning in order to identify the suppressor genes is in progress.

NMD Microarray Analysis for Rapid Genome-Wide Screen of Mutated Genes in Cancer

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Maija Wolf

2005-01-01

Full Text Available Gene mutations play a critical role in cancer development and progression, and their identification offers possibilities for accurate diagnostics and therapeutic targeting. Finding genes undergoing mutations is challenging and slow, even in the post-genomic era. A new approach was recently developed by Noensie and Dietz to prioritize and focus the search, making use of nonsense-mediated mRNA decay (NMD inhibition and microarray analysis (NMD microarrays in the identification of transcripts containing nonsense mutations. We combined NMD microarrays with array-based CGH (comparative genomic hybridization in order to identify inactivation of tumor suppressor genes in cancer. Such a “mutatomics” screening of prostate cancer cell lines led to the identification of inactivating mutations in the EPHB2 gene. Up to 8% of metastatic uncultured prostate cancers also showed mutations of this gene whose loss of function may confer loss of tissue architecture. NMD microarray analysis could turn out to be a powerful research method to identify novel mutated genes in cancer cell lines, providing targets that could then be further investigated for their clinical relevance and therapeutic potential.

Induction of specific suppressor T cells in vitro

International Nuclear Information System (INIS)

Eardley, D.D.; Gershon, R.K.

1976-01-01

We describe conditions for generating sheep red blood cell-specific suppressor T cells in Mishell-Dutton cultures. The production of specific suppressor cells is favored by increasing antigen dose in the initial culture but can be produced by transferring more cells when lower doses of antigen are used. Transfer of small numbers of cells cultured with low doses of antigen leads to a specific helper effect. Transfer of large numbers of educated cells leads to nonspecific suppression. Suppression can be effected by the effluent cells from nylon wool columns which do not make detectable PFC. A fraction of these cells become resistant to treatment with anti-T cell sera and complement after culture. The suppressor cells are radiation sensitive and must be able to synthesize protein to suppress. They take 2 to 3 days of education to reach maximum suppressive efficiency and will not suppress cultures if added 2 to 3 days after culture initiation. Their production is favored by the absence of mercaptoethanol, suggesting that the observed suppression is not ''too much help.'' The ability to generate specific suppressor cells in vitro should be of great benefit in determining the factors that regulate their appearance in vivo

Identification of a novel BRCA1 nucleotide 4803delCC/c.4684delCC mutation and a nucleotide 249T>A/c.130T>A (p.Cys44Ser) mutation in two Greenlandic Inuit families

DEFF Research Database (Denmark)

Hansen, Thomas van Overeem; Jønson, Lars; Albrechtsen, Anders

2010-01-01

Germ-line mutations in the tumour suppressor proteins BRCA1 and BRCA2 predispose to breast and ovarian cancer. We have recently identified a Greenlandic Inuit BRCA1 nucleotide 234T>G/c.115T>G (p.Cys39Gly) founder mutation, which at that time was the only disease-causing BRCA1/BRCA2 mutation...... identified in this population. Here, we describe the identification of a novel disease-causing BRCA1 nucleotide 4803delCC/c.4684delCC mutation in a Greenlandic Inuit with ovarian cancer. The mutation introduces a frameshift and a premature stop at codon 1572. We have also identified a BRCA1 nucleotide 249T......>A/c.130T>A (p.Cys44Ser) mutation in another Greenlandic individual with ovarian cancer. This patient share a 1-2 Mb genomic fragment, containing the BRCA1 gene, with four Danish families harbouring the same mutation, suggesting that the 249T>A/c.130T>A (p.Cys44Ser) mutation originates from a Danish...

Soluble suppressor supernatants elaborated by concanavalin A-activated human mononuclear cells. Characterization of a soluble suppressor of B cell immunoglobulin production

International Nuclear Information System (INIS)

Fleisher, T.A.; Greene, W.C.; Blaese, R.M.; Waldmann, T.A.

1981-01-01

Human peripheral blood mononuclear cells (PBMC) activated with the mitogenic lectin concanavalin A (Con A) elaborate a soluble immune suppressor supernatant (SISS) that contains at least 2 distinct suppressor factors. One of these, SISS-B, inhibits polyclonal B cell immunoglobulin production, whereas the other, SISS-T, suppresses T cell proliferation to both mitogens and antigens. The latter mediator is discussed in the companion paper. Characteristics of the human soluble suppressor of B cell immunoglobulin production (SISS-B) include: 1) inhibition by a noncytotoxic mechanism, 2) loss of activity in the presence of the monosaccharide L-rhamnose, 3) appearance within 8 to 16 hr after the addition of Con A, 4) elaboration by cells irradiated with 500 or 2000 rads, 5) production by highly purified T cells, 6) stability at pH 2.5 but instability at 56/sup o/C, and 7) m.w. of 60 to 80,000. These data indicate that after Con A activation, selected T cells not only become potent suppressor cells, but also generate a soluble saccharide-specific factor(s) that inhibits polyclonal immunoglobulin production by human B cells

Infrared suppressor effect on T63 turboshaft engine performance

Science.gov (United States)

Bailey, E. E.; Civinskas, K. C.; Walker, C. L.

1978-01-01

Tests were conducted to determine if there are performance penalties associated with the installation of infrared (IR) suppressors on the T63-A-700 turboshaft engine. The testing was done in a sea-level, static test cell. The same engine (A-E402808 B) was run with the standard OH-58 aircraft exhaust stacks and with the ejector-type IR suppressors in order to make a valid comparison. Repeatability of the test results for the two configurations was verified by rerunning the conditions over a period of days. Test results showed no measurable difference in performance between the standard exhaust stacks and the IR suppressors.

MicroRNA-103 Promotes Colorectal Cancer by Targeting Tumor Suppressor DICER and PTEN

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Li Geng

2014-05-01

Full Text Available MicroRNAs (miRNAs are a class of small, noncoding RNAs that act as key regulators in various physiological and pathological processes. However, the regulatory mechanisms for miRNAs in colorectal cancer remain largely unknown. Here, we found that miR-103 is up-regulated in colorectal cancer and its overexpression is closely associated with tumor proliferation and migration. In addition, repressing the expression of miR-103 apparently inhibits colorectal cancer cell proliferation and migration in vitro and HCT-116 xenograft tumor growth in vivo. Subsequent software analysis and dual-luciferase reporter assay identified two tumor suppressor genes DICER and PTEN as direct targets of miR-103, and up-regulation of DICER and PTEN obtained similar results to that occurred in the silencing of miR-103. In addition, restoration of DICER and PTEN can inhibit miR-103-induced colorectal cancer cell proliferation and migration. Our data collectively demonstrate that miR-103 is an oncogene miRNA that promotes colorectal cancer proliferation and migration through down-regulation of the tumor suppressor genes DICER and PTEN. Thus, miR-103 may represent a new potential diagnostic and therapeutic target for colorectal cancer treatment.

Enlightened protein: Fhit tumor suppressor protein structure and function and its role in the toxicity of protoporphyrin IX-mediated photodynamic reaction

International Nuclear Information System (INIS)

Zawacka-Pankau, Joanna

2009-01-01

The Fhit tumor suppressor protein possesses Ap 3 A (diadenosine triphosphate - ApppA) hydrolytic activity in vitro and its gene is found inactive in many pre-malignant states due to gene inactivation. For several years Fhit has been a widely investigated protein as its cellular function still remains largely unsolved. Fhit was shown to act as a molecular 'switch' of cell death via cascade operating on the influence of ATR-Chk1 pathway but also through the mitochondrial apoptotic pathway. Notably, Fhit was reported by our group to enhance the overall eradication effect of porphyrin-mediated photodynamic treatment (PDT). In this review the up-to-date findings on Fhit protein as a tumor suppressor and its role in PDT are presented.

Mms Sensitivity of All Amino Acid-Requiring Mutants in Aspergillus and Its Suppression by Mutations in a Single Gene

OpenAIRE

Käfer, Etta

1987-01-01

All available amino acid-requiring mutants of Aspergillus nidulans were found to be hypersensitive to MMS (methyl methanesulfonate) to various degrees. On MMS media, secondary mutations could be selected which suppress this MMS sensitivity but do not affect the requirement. Many such mutations were analyzed and found to be alleles of one gene, smsA (= suppressor of MMS sensitivity), which mapped distal on the right arm of chromosome V. This gene is more likely to be involved in general regula...

The Quest for the 1p36 Tumor Suppressor

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Bagchi, Anindya; Mills, Alea A.

2010-01-01

Genomic analyses of late-stage human cancers have uncovered deletions encompassing 1p36, thereby providing an extensive body of literature supporting the idea that a potent tumor suppressor resides in this interval. Although a number of genes have been proposed as 1p36 candidate tumor suppressors, convincing evidence that their encoded products protect from cancer has been scanty. A recent functional study identified CHD5 as a novel tumor suppressor mapping to 1p36. Here we discuss evidence supporting CHD5’s tumor suppressive role. Together, these findings suggest that strategies designed to enhance CHD5 activity could provide novel approaches for treating a broad range of human malignancies. PMID:18413720

A Point Mutation in Suppressor of Cytokine Signalling 2 (Socs2 Increases the Susceptibility to Inflammation of the Mammary Gland while Associated with Higher Body Weight and Size and Higher Milk Production in a Sheep Model.

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Rachel Rupp

2015-12-01

Full Text Available Mastitis is an infectious disease mainly caused by bacteria invading the mammary gland. Genetic control of susceptibility to mastitis has been widely evidenced in dairy ruminants, but the genetic basis and underlying mechanisms are still largely unknown. We describe the discovery, fine mapping and functional characterization of a genetic variant associated with elevated milk leukocytes count, or SCC, as a proxy for mastitis. After implementing genome-wide association studies, we identified a major QTL associated with SCC on ovine chromosome 3. Fine mapping of the region, using full sequencing with 12X coverage in three animals, provided one strong candidate SNP that mapped to the coding sequence of a highly conserved gene, suppressor of cytokine signalling 2 (Socs2. The frequency of the SNP associated with increased SCC was 21.7% and the Socs2 genotype explained 12% of the variance of the trait. The point mutation induces the p.R96C substitution in the SH2 functional domain of SOCS2 i.e. the binding site of the protein to various ligands, as well-established for the growth hormone receptor GHR. Using surface plasmon resonance we showed that the p.R96C point mutation completely abrogates SOCS2 binding affinity for the phosphopeptide of GHR. Additionally, the size, weight and milk production in p.R96C homozygote sheep, were significantly increased by 24%, 18%, and 4.4%, respectively, when compared to wild type sheep, supporting the view that the point mutation causes a loss of SOCS2 functional activity. Altogether these results provide strong evidence for a causal mutation controlling SCC in sheep and highlight the major role of SOCS2 as a tradeoff between the host's inflammatory response to mammary infections, and body growth and milk production, which are all mediated by the JAK/STAT signaling pathway.

Clonal architectures and driver mutations in metastatic melanomas.

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Li Ding

Full Text Available To reveal the clonal architecture of melanoma and associated driver mutations, whole genome sequencing (WGS and targeted extension sequencing were used to characterize 124 melanoma cases. Significantly mutated gene analysis using 13 WGS cases and 15 additional paired extension cases identified known melanoma genes such as BRAF, NRAS, and CDKN2A, as well as a novel gene EPHA3, previously implicated in other cancer types. Extension studies using tumors from another 96 patients discovered a large number of truncation mutations in tumor suppressors (TP53 and RB1, protein phosphatases (e.g., PTEN, PTPRB, PTPRD, and PTPRT, as well as chromatin remodeling genes (e.g., ASXL3, MLL2, and ARID2. Deep sequencing of mutations revealed subclones in the majority of metastatic tumors from 13 WGS cases. Validated mutations from 12 out of 13 WGS patients exhibited a predominant UV signature characterized by a high frequency of C->T transitions occurring at the 3' base of dipyrimidine sequences while one patient (MEL9 with a hypermutator phenotype lacked this signature. Strikingly, a subclonal mutation signature analysis revealed that the founding clone in MEL9 exhibited UV signature but the secondary clone did not, suggesting different mutational mechanisms for two clonal populations from the same tumor. Further analysis of four metastases from different geographic locations in 2 melanoma cases revealed phylogenetic relationships and highlighted the genetic alterations responsible for differential drug resistance among metastatic tumors. Our study suggests that clonal evaluation is crucial for understanding tumor etiology and drug resistance in melanoma.

Mutational analysis of FLASH and PTPN13 genes in colorectal carcinomas.

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Jeong, Eun Goo; Lee, Sung Hak; Yoo, Nam Jin; Lee, Sug Hyung

2008-01-01

The Fas-Fas ligand system is considered a major pathway for induction of apoptosis in cells and tissues. FLASH was identified as a pro-apoptotic protein that transmits apoptosis signal during Fas-mediated apoptosis. PTPN13 interacts with Fas and functions as both suppressor and inducer of Fas-mediated apoptosis. There are polyadenine tracts in both FLASH (A8 and A9 in exon 8) and PTPN13 (A8 in exon 7) genes that could be frameshift mutation targets in colorectal carcinomas. Because genes encoding proteins in Fas-mediated apoptosis frequently harbor somatic mutations in cancers, we explored the possibility as to whether mutations of FLASH and PTPN13 are a feature of colorectal carcinomas. We analysed human FLASH in exon 8 and PTPN13 in exon 7 for the detection of somatic mutations in 103 colorectal carcinomas by a polymerase chain reaction (PCR)- based single-strand conformation polymorphism (SSCP). We detected two mutations in FLASH gene, but none in PTPN13 gene. However, the two mutations were not frameshift (deletion or insertion) mutations in the polyadenine tracts of FLASH. The two mutations consisted of a deletion mutation (c.3734-3737delAGAA) and a missense mutation (c.3703A>C). These data indicate that frameshift mutation in the polyadenine tracts in both FLASH and PTPN13 genes is rare in colorectal carcinomas. Also, the data suggest that both FLASH and PTPN13 mutations in the polyadenine tracts may not have a crucial role in the pathogenesis of colorectal carcinomas.

The APC tumor suppressor is required for epithelial cell polarization and three-dimensional morphogenesis

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Lesko, Alyssa C.; Goss, Kathleen H.; Yang, Frank F.; Schwertner, Adam; Hulur, Imge; Onel, Kenan; Prosperi, Jenifer R.

2015-01-01

The Adenomatous Polyposis Coli (APC) tumor suppressor has been previously implicated in the control of apical-basal polarity; yet, the consequence of APC loss-of-function in epithelial polarization and morphogenesis has not been characterized. To test the hypothesis that APC is required for the establishment of normal epithelial polarity and morphogenesis programs, we generated APC-knockdown epithelial cell lines. APC depletion resulted in loss of polarity and multi-layering on permeable supports, and enlarged, filled spheroids with disrupted polarity in 3D culture. Importantly, these effects of APC knockdown were independent of Wnt/β-catenin signaling, but were rescued with either full-length or a carboxy (c)-terminal segment of APC. Moreover, we identified a gene expression signature associated with APC knockdown that points to several candidates known to regulate cell-cell and cell-matrix communication. Analysis of epithelial tissues from mice and humans carrying heterozygous APC mutations further support the importance of APC as a regulator of epithelial behavior and tissue architecture. These data also suggest that the initiation of epithelial-derived tumors as a result of APC mutation or gene silencing may be driven by loss of polarity and dysmorphogenesis. PMID:25578398

A targeted constitutive mutation in the APC tumor suppressor gene underlies mammary but not intestinal tumorigenesis.

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Claudia Gaspar

2009-07-01

Full Text Available Germline mutations in the adenomatous polyposis coli (APC gene are responsible for familial adenomatous polyposis (FAP, an autosomal dominant hereditary predisposition to the development of multiple colorectal adenomas and of a broad spectrum of extra-intestinal tumors. Moreover, somatic APC mutations play a rate-limiting and initiating role in the majority of sporadic colorectal cancers. Notwithstanding its multifunctional nature, the main tumor suppressing activity of the APC gene resides in its ability to regulate Wnt/beta-catenin signaling. Notably, genotype-phenotype correlations have been established at the APC gene between the length and stability of the truncated proteins encoded by different mutant alleles, the corresponding levels of Wnt/beta-catenin signaling activity they encode for, and the incidence and distribution of intestinal and extra-intestinal tumors. Here, we report a novel mouse model, Apc1572T, obtained by targeting a truncated mutation at codon 1572 in the endogenous Apc gene. This hypomorphic mutant allele results in intermediate levels of Wnt/beta-catenin signaling activation when compared with other Apc mutations associated with multifocal intestinal tumors. Notwithstanding the constitutive nature of the mutation, Apc(+/1572T mice have no predisposition to intestinal cancer but develop multifocal mammary adenocarcinomas and subsequent pulmonary metastases in both genders. The histology of the Apc1572T primary mammary tumours is highly heterogeneous with luminal, myoepithelial, and squamous lineages and is reminiscent of metaplastic carcinoma of the breast in humans. The striking phenotype of Apc(+/1572T mice suggests that specific dosages of Wnt/beta-catenin signaling activity differentially affect tissue homeostasis and initiate tumorigenesis in an organ-specific fashion.

Negative Regulation of the Stability and Tumor Suppressor Function of Fbw7 by the Pin1 Prolyl Isomerase

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Min, Sang-Hyun; Lau, Alan W.; Lee, Tae Ho; Inuzuka, Hiroyuki; Wei, Shuo; Huang, Pengyu; Shaik, Shavali; Lee, Daniel Yenhong; Finn, Greg; Balastik, Martin; Chen, Chun-Hau; Luo, Manli; Tron, Adriana E.; DeCaprio, James A.; Zhou, Xiao Zhen; Wei, Wenyi; Lu, Kun Ping

2012-01-01

SUMMARY Fbw7 is the substrate recognition component of the SCF (Skp1-Cullin-F-box)-type E3 ligase complex and a well-characterized tumor suppressor that targets numerous oncoproteins for destruction. Genomic deletion or mutation of FBW7 has been frequently found in various types of human cancers, however, little is known about the upstream signaling pathway(s) governing Fbw7 stability and cellular functions. Here we report that Fbw7 protein destruction and tumor suppressor function are negatively regulated by the prolyl isomerase Pin1. Pin1 interacts with Fbw7 in a phoshorylation-dependent manner and promotes Fbw7 self-ubiquitination and protein degradation by disrupting Fbw7 dimerization. Consequently, over-expressing Pin1 reduces Fbw7 abundance and suppresses Fbw7’s ability to inhibit proliferation and transformation. By contrast, depletion of Pin1 in cancer cells leads to elevated Fbw7 expression, which subsequently reduces Mcl-1 abundance, sensitizing cancer cells to Taxol. Thus, Pin1-mediated inhibition of Fbw7 contributes to oncogenesis and Pin1 may be a promising drug target for anti-cancer therapy. PMID:22608923

Use of human tissue to assess the oncogenic activity of melanoma-associated mutations.

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Chudnovsky, Yakov; Adams, Amy E; Robbins, Paul B; Lin, Qun; Khavari, Paul A

2005-07-01

Multiple genetic alterations occur in melanoma, a lethal skin malignancy of increasing incidence. These include mutations that activate Ras and two of its effector cascades, Raf and phosphoinositide 3-kinase (PI3K). Induction of Ras and Raf can be caused by active N-Ras and B-Raf mutants as well as by gene amplification. Activation of PI3K pathway components occurs by PTEN loss and by AKT3 amplification. Melanomas also commonly show impairment of the p16(INK4A)-CDK4-Rb and ARF-HDM2-p53 tumor suppressor pathways. CDKN2A mutations can produce p16(INK4A) and ARF protein loss. Rb bypass can also occur through activating CDK4 mutations as well as by CDK4 amplification. In addition to ARF deletion, p53 pathway disruption can result from dominant negative TP53 mutations. TERT amplification also occurs in melanoma. The extent to which these mutations can induce human melanocytic neoplasia is unknown. Here we characterize pathways sufficient to generate human melanocytic neoplasia and show that genetically altered human tissue facilitates functional analysis of mutations observed in human tumors.

Genetic screening of the FLCN gene identify six novel variants and a Danish founder mutation

DEFF Research Database (Denmark)

Rossing, Maria; Albrechtsen, Anders; Skytte, Anne-Bine

2016-01-01

Pathogenic germline mutations in the folliculin (FLCN) tumor suppressor gene predispose to Birt-Hogg-Dubé (BHD) syndrome, a rare disease characterized by the development of cutaneous hamartomas (fibrofolliculomas), multiple lung cysts, spontaneous pneumothoraces and renal cell cancer. In this stu...... understanding of BHD syndrome and management of BHD patients.Journal of Human Genetics advance online publication, 13 October 2016; doi:10.1038/jhg.2016.118....

Somatic Mutational Landscape of Splicing Factor Genes and Their Functional Consequences across 33 Cancer Types

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Michael Seiler

2018-04-01

Full Text Available Summary: Hotspot mutations in splicing factor genes have been recently reported at high frequency in hematological malignancies, suggesting the importance of RNA splicing in cancer. We analyzed whole-exome sequencing data across 33 tumor types in The Cancer Genome Atlas (TCGA, and we identified 119 splicing factor genes with significant non-silent mutation patterns, including mutation over-representation, recurrent loss of function (tumor suppressor-like, or hotspot mutation profile (oncogene-like. Furthermore, RNA sequencing analysis revealed altered splicing events associated with selected splicing factor mutations. In addition, we were able to identify common gene pathway profiles associated with the presence of these mutations. Our analysis suggests that somatic alteration of genes involved in the RNA-splicing process is common in cancer and may represent an underappreciated hallmark of tumorigenesis. : Seiler et al. report that 119 splicing factor genes carry putative driver mutations over 33 tumor types in TCGA. The most common mutations appear to be mutually exclusive and are associated with lineage-independent altered splicing. Samples with these mutations show deregulation of cell-autonomous pathways and immune infiltration. Keywords: splicing, SF3B1, U2AF1, SRSF2, RBM10, FUBP1, cancer, mutation

In vitro X-ray irradiation of human peripheral blood T lymphocytes enhances suppressor function

International Nuclear Information System (INIS)

Ogawa, H.; Tsunematsu, T.

1983-01-01

The effect of in vitro X-ray irradiation on human peripheral blood T lymphocytes was studied with regard to their suppressor activity related to the concanavalin A (Con A)-induced suppressor system. To generate suppressor T lymphocytes, purified human T lymphocytes were incubated for 3 days in the first culture, with or without Con A. These lymphocytes were irradiated with various doses of X-ray before, mid or after the culture. After doing a second culture for 6 days, the suppressive influence of these cells on T lymphocyte proliferation rates stimulated with allogeneic mononuclear cells, and B lymphocyte proliferation rates stimulated with pokeweed mitogen was measured. Irradiation of cultures to which Con A had not been added induced much the same level of suppressor activity as seen in the cultures with Con A. The suppressor activity gradually increased with time from the irradiation to the suppressor cell assay. Suppressor T lymphocytes were resistant to X-ray irradiation and independent of DNA synthesis. However, irradiation-induced enhancement was minimal in cultures incubated with con A, regardless of the irradiation time. (author)

CP-31398 prevents the growth of p53-mutated colorectal cancer cells in vitro and in vivo.

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He, Xingxing; Kong, Xinjuan; Yan, Junwei; Yan, Jingjun; Zhang, Yunan; Wu, Qian; Chang, Ying; Shang, Haitao; Dou, Qian; Song, Yuhu; Liu, Fang

2015-03-01

Rescuing the function of mutant p53 protein is an attractive cancer therapeutic strategy. Small molecule CP-31398 was shown to restore mutant p53 tumor suppressor functions in cancer cells. Here, we determined the effects of CP-31398 on the growth of p53-mutated colorectal cancer (CRC) cells in vitro and in vivo. CRC cells which carry p53 mutation in codon 273 were treated with CP-31398 and the control, and the effects of CP-31398 on cell cycle, cell apoptosis, and proliferation were determined. The expression of p53-responsive downstream genes was evaluated by quantitative reverse transcriptase PCR (RT-PCR) and Western blot. CP-31398 was administrated into xenograft tumors created by the inoculation of HT-29 cells, and then the effect of CP-31398 on the growth of xenograft tumors was examined. CP-31398 induced p53 downstream target molecules in cultured HT-29 cells, which resulted in the inhibition of CRC cell growth assessed by the determination of cell cycle, apoptosis, and cell proliferation. In xenograft tumors, CP-31398 modulated the expression of Bax, Bcl-2, caspase 3, cyclin D, and Mdm2 and then blocked the growth of xenograft tumors. CP-31398 would be developed as a therapeutic candidate for p53-mutated CRC due to the restoration of mutant p53 tumor suppressor functions.

Myeloid malignancies: mutations, models and management

International Nuclear Information System (INIS)

Murati, Anne; Brecqueville, Mandy; Devillier, Raynier; Mozziconacci, Marie-Joelle; Gelsi-Boyer, Véronique; Birnbaum, Daniel

2012-01-01

Myeloid malignant diseases comprise chronic (including myelodysplastic syndromes, myeloproliferative neoplasms and chronic myelomonocytic leukemia) and acute (acute myeloid leukemia) stages. They are clonal diseases arising in hematopoietic stem or progenitor cells. Mutations responsible for these diseases occur in several genes whose encoded proteins belong principally to five classes: signaling pathways proteins (e.g. CBL, FLT3, JAK2, RAS), transcription factors (e.g. CEBPA, ETV6, RUNX1), epigenetic regulators (e.g. ASXL1, DNMT3A, EZH2, IDH1, IDH2, SUZ12, TET2, UTX), tumor suppressors (e.g. TP53), and components of the spliceosome (e.g. SF3B1, SRSF2). Large-scale sequencing efforts will soon lead to the establishment of a comprehensive repertoire of these mutations, allowing for a better definition and classification of myeloid malignancies, the identification of new prognostic markers and therapeutic targets, and the development of novel therapies. Given the importance of epigenetic deregulation in myeloid diseases, the use of drugs targeting epigenetic regulators appears as a most promising therapeutic approach

The Inherited p53 Mutation in the Brazilian Population.

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Achatz, Maria Isabel; Zambetti, Gerard P

2016-12-01

A common criticism of studying rare diseases is the often-limited relevance of the findings to human health. Here, we review ∼15 years of research into an unusual germline TP53 mutation (p.R337H) that began with its detection in children with adrenocortical carcinoma (ACC), a remarkably rare childhood cancer that is associated with poor prognosis. We have come to learn that the p.R337H mutation exists at a very high frequency in Southern and Southeastern Brazil, occurring in one of 375 individuals within a total population of ∼100 million. Moreover, it has been determined that carriers of this founder mutation display variable tumor susceptibility, ranging from isolated cases of pediatric ACC to Li-Fraumeni or Li-Fraumeni-like (LFL) syndromes, thus representing a significant medical issue for this country. Studying the biochemical and molecular consequences of this mutation on p53 tumor-suppressor activity, as well as the putative additional genetic alterations that cooperate with this mutation, is advancing our understanding of how p53 functions in tumor suppression in general. These studies, which originated with a rare childhood tumor, are providing important information for guiding genetic counselors and physicians in treating their patients and are already providing clinical benefit. Copyright © 2016 Cold Spring Harbor Laboratory Press; all rights reserved.

Regulatory role for the memory B cell as suppressor-inducer of feedback control

International Nuclear Information System (INIS)

Kennedy, M.W.; Thomas, D.B.

1983-01-01

A regulatory role is proposed for the antigen-responsive B cell, as suppressor-inducer of feedback control during the secondary response in vivo. In a double adoptive transfer of memory cells primed to a thymus-dependent antigen from one irradiated host to another, antigen-specific suppressors are generated after a critical time in the primary recipient, able to entirely ablate a secondary anti-hapten response. Positive cell selection in the fluorescence-activated cell sorter confirmed that suppression was mediated by an Lyt-2+ T cell; however, positively selected B cells were also inhibitory and able to induce suppressors in a carrier-specific manner: B hapten induced suppressors in a carrier-primed population, and B carrier induced suppressors in a hapten-carrier population. At the peak of the antibody response in the primary host, memory B cells and their progeny were unable to differentiate further to plasma cells due to their intrinsic suppressor-inducer activity, but this autoregulatory circuit could be severed by adoptive transfer to carrier-primed, X-irradiated recipients

SMARCB1/INI1 germline mutations contribute to 10% of sporadic schwannomatosis

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Bourdon Violaine

2011-01-01

Full Text Available Abstract Background Schwannomatosis is a disease characterized by multiple non-vestibular schwannomas. Although biallelic NF2 mutations are found in schwannomas, no germ line event is detected in schwannomatosis patients. In contrast, germline mutations of the SMARCB1 (INI1 tumor suppressor gene were described in familial and sporadic schwannomatosis patients. Methods To delineate the SMARCB1 gene contribution, the nine coding exons were sequenced in a series of 56 patients affected with a variable number of non-vestibular schwannomas. Results Nine variants scattered along the sequence of SMARCB1 were identified. Five of them were classified as deleterious. All five patients carrying a SMARCB1 mutation had more multiple schwannomas, corresponding to 10.2% of patients with schwannomatosis. They were also diagnosed before 35 years of age. Conclusions These results suggest that patients with schwannomas have a significant probability of carrying a SMARCB1 mutation. Combined with data available from other studies, they confirm the clinical indications for genetic screening of the SMARCB1 gene.

Requirement of the ATM/p53 tumor suppressor pathway for glucose homeostasis.

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Armata, Heather L; Golebiowski, Diane; Jung, Dae Young; Ko, Hwi Jin; Kim, Jason K; Sluss, Hayla K

2010-12-01

Ataxia telangiectasia (A-T) patients can develop multiple clinical pathologies, including neuronal degeneration, an elevated risk of cancer, telangiectasias, and growth retardation. Patients with A-T can also exhibit an increased risk of insulin resistance and type 2 diabetes. The ATM protein kinase, the product of the gene mutated in A-T patients (Atm), has been implicated in metabolic disease, which is characterized by insulin resistance and increased cholesterol and lipid levels, blood pressure, and atherosclerosis. ATM phosphorylates the p53 tumor suppressor on a site (Ser15) that regulates transcription activity. To test whether the ATM pathway that regulates insulin resistance is mediated by p53 phosphorylation, we examined insulin sensitivity in mice with a germ line mutation that replaces the p53 phosphorylation site with alanine. The loss of p53 Ser18 (murine Ser15) led to increased metabolic stress, including severe defects in glucose homeostasis. The mice developed glucose intolerance and insulin resistance. The insulin resistance correlated with the loss of antioxidant gene expression and decreased insulin signaling. N-Acetyl cysteine (NAC) treatment restored insulin signaling in late-passage primary fibroblasts. The addition of an antioxidant in the diet rendered the p53 Ser18-deficient mice glucose tolerant. This analysis demonstrates that p53 phosphorylation on an ATM site is an important mechanism in the physiological regulation of glucose homeostasis.

Primary microcephaly gene MCPH1 shows signatures of tumor suppressors and is regulated by miR-27a in oral squamous cell carcinoma.

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Thejaswini Venkatesh

Full Text Available Mutations in the MCPH1 (microcephalin 1 gene, located at chromosome 8p23.1, result in two autosomal recessive disorders: primary microcephaly and premature chromosome condensation syndrome. MCPH1 has also been shown to be downregulated in breast, prostate and ovarian cancers, and mutated in 1/10 breast and 5/41 endometrial tumors, suggesting that it could also function as a tumor suppressor (TS gene. To test the possibility of MCPH1 as a TS gene, we first performed LOH study in a panel of 81 matched normal oral tissues and oral squamous cell carcinoma (OSCC samples, and observed that 14/71 (19.72% informative samples showed LOH, a hallmark of TS genes. Three protein truncating mutations were identified in 1/15 OSCC samples and 2/5 cancer cell lines. MCPH1 was downregulated at both the transcript and protein levels in 21/41 (51.22% and 19/25 (76% OSCC samples respectively. A low level of MCPH1 promoter methylation was also observed in 4/40 (10% tumor samples. We further observed that overexpression of MCPH1 decreased cellular proliferation, anchorage-independent growth in soft agar, cell invasion and tumor size in nude mice, indicating its tumor suppressive function. Using bioinformatic approaches and luciferase assay, we showed that the 3'-UTR of MCPH1 harbors two non-overlapping functional seed regions for miR-27a which negatively regulated its level. The expression level of miR-27a negatively correlated with the MCPH1 protein level in OSCC. Our study indicates for the first time that, in addition to its role in brain development, MCPH1 also functions as a tumor suppressor gene and is regulated by miR-27a.

Determination of Heritage SSME Pogo Suppressor Resistance and Inertance from Waterflow Pulse Testing

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McDougal, Chris; Eberhart, Chad; Lee, Erik

2016-01-01

Waterflow tests of a heritage Space Shuttle Main Engine pogo suppressor were performed to experimentally quantify the resistance and inertance provided by the suppressor. Measurements of dynamic pressure and flow rate in response to pulsing flow were made throughout the test loop. A unique system identification methodology combined all sensor measurements with a one-dimensional perturbational flow model of the complete water flow loop to spatially translate physical measurements to the device under test. Multiple techniques were then employed to extract the effective resistance and inertance for the pogo suppressor. Parameters such as steady flow rate, perturbational flow rate magnitude, and pulse frequency were investigated to assess their influence on the behavior of the pogo suppressor dynamic response. These results support validation of the RS-25 pogo suppressor performance for use on the Space Launch System Core Stage.

Changes in helper and suppressor T lymphocytes following radiotherapy for breast cancer

International Nuclear Information System (INIS)

Newman, G.H.; Rees, G.J.G.; Jones, R.S.J.; Grove, E.A.; Preece, A.W.

1987-01-01

Changes in total lymphocyte, T lymphocyte, T helper and T suppressor lymphocyte numbers were studied in 22 patients with breast cancer before and after radiotherapy. T lymphocyte subsets were measured using monoclonal antibodies and fluorescence microscopy. After treatment the total lymphocyte count fell significantly and was still reduced 9 months later, but the proportion of cells labelled as T lymphocytes was unchanged during this period. The helper-suppressor ratio, which was within the normal range before radiotherapy, was significantly reduced at 3 months and 9 months after. Following treatment both T helper and T suppressor cell numbers were significantly reduced. T helper cell numbers remained reduced throughout the study period but T suppressor cell numbers showed a recovery to normal values 9 months after radiotherapy. (author)

TP53 Mutations in Nonsmall Cell Lung Cancer

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Akira Mogi

2011-01-01

Full Text Available The tumor suppressor gene TP53 is frequently mutated in human cancers. Abnormality of the TP53 gene is one of the most significant events in lung cancers and plays an important role in the tumorigenesis of lung epithelial cells. Human lung cancers are classified into two major types, small cell lung cancer (SCLC and nonsmall cell lung cancer (NSCLC. The latter accounts for approximately 80% of all primary lung cancers, and the incidence of NSCLC is increasing yearly. Most clinical studies suggest that NSCLC with TP53 alterations carries a worse prognosis and may be relatively more resistant to chemotherapy and radiation. A deep understanding of the role of TP53 in lung carcinogenesis may lead to a more reasonably targeted clinical approach, which should be exploited to enhance the survival rates of patients with lung cancer. This paper will focus on the role of TP53 in the molecular pathogenesis, epidemiology, and therapeutic strategies of TP53 mutation in NSCLC.

Regulating Prostate Cancer Sensitivity to Chemotherapy through Translational Control of CCAAT/Enhancer Binding Proteins

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2016-10-01

signaling pathways. Indeed, it has been reported that 50-70% of human prostate cancers have mutations in PI3K signaling, often through loss of phosphatase...function to increase cell growth and act as silencers of tumor suppressor pathways. For example, mutation of the CEBPα gene locus, so that only the...Ueno, A. Yamamoto, T. Kirisako, T. Noda, et al., LC3, a mammalian homologue of yeast Apg8p, is localized in autophagosome membranes after processing

Germline mutations in MAP3K6 are associated with familial gastric cancer.

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Daniel Gaston

2014-10-01

Full Text Available Gastric cancer is among the leading causes of cancer-related deaths worldwide. While heritable forms of gastric cancer are relatively rare, identifying the genes responsible for such cases can inform diagnosis and treatment for both hereditary and sporadic cases of gastric cancer. Mutations in the E-cadherin gene, CDH1, account for 40% of the most common form of familial gastric cancer (FGC, hereditary diffuse gastric cancer (HDGC. The genes responsible for the remaining forms of FGC are currently unknown. Here we examined a large family from Maritime Canada with FGC without CDH1 mutations, and identified a germline coding variant (p.P946L in mitogen-activated protein kinase kinase kinase 6 (MAP3K6. Based on conservation, predicted pathogenicity and a known role of the gene in cancer predisposition, MAP3K6 was considered a strong candidate and was investigated further. Screening of an additional 115 unrelated individuals with non-CDH1 FGC identified the p.P946L MAP3K6 variant, as well as four additional coding variants in MAP3K6 (p.F849Sfs*142, p.P958T, p.D200Y and p.V207G. A somatic second-hit variant (p.H506Y was present in DNA obtained from one of the tumor specimens, and evidence of DNA hypermethylation within the MAP3K6 gene was observed in DNA from the tumor of another affected individual. These findings, together with previous evidence from mouse models that MAP3K6 acts as a tumor suppressor, and studies showing the presence of somatic mutations in MAP3K6 in non-hereditary gastric cancers and gastric cancer cell lines, point towards MAP3K6 variants as a predisposing factor for FGC.

Visualization of plant viral suppressor silencing activity in intact leaf lamina by quantitative fluorescent imaging

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Francis Kevin P

2011-08-01

Full Text Available Abstract Background Transient expression of proteins in plants has become a favoured method over the production of stably transformed plants because, in addition to enabling high protein yields, it is both fast and easy to apply. An enhancement of transient protein expression can be achieved by plant virus-encoded RNA silencing suppressor proteins. Since viral suppressor proteins differ in their efficiency to enhance transient protein expression in plants, we developed a whole-leaf green fluorescent protein (GFP-based imaging assay to quantitatively assess suppressor protein activity. Results In a transient GFP-expression assay using wild-type and GFP-transgenic N. benthamiana, addition of the plant viral suppressors Beet mild yellowing virus (BMYV-IPP P0 or Plum pox virus (PPV HC-Pro was shown to increase fluorescent protein expression 3-4-fold, 7 days post inoculation (dpi when compared to control plants. In contrast, in agroinfiltrated patches without suppressor activity, near complete silencing of the GFP transgene was observed in the transgenic N. benthamiana at 21 dpi. Both co-infiltrated suppressors significantly enhanced GFP expression over time, with HC-Pro co-infiltrations leading to higher short term GFP fluorescence (at 7 dpi and P0 giving higher long term GFP fluorescence (at 21 dpi. Additionally, in contrast to HC-Pro co-infiltrations, an area of complete GFP silencing was observed at the edge of P0 co-infiltrated areas. Conclusions Fluorescence imaging of whole intact leaves proved to be an easy and effective method for spatially and quantitatively observing viral suppressor efficiency in plants. This suppressor assay demonstrates that plant viral suppressors greatly enhanced transient GFP expression, with P0 showing a more prolonged suppressor activity over time than HC-Pro. Both suppressors could prove to be ideal candidates for enhancing target protein expression in plants.

Consecutive epigenetically-active agent combinations act in ID1-RUNX3-TET2 and HOXA pathways for Flt3ITD+ve AML.

Science.gov (United States)

Sayar, Hamid; Liu, Yan; Gao, Rui; Zaid, Mohammad Abu; Cripe, Larry D; Weisenbach, Jill; Sargent, Katie J; Nassiri, Mehdi; Li, Lang; Konig, Heiko; Suvannasankha, Attaya; Pan, Feng; Shanmugam, Rajasubramaniam; Goswami, Chirayu; Kapur, Reuben; Xu, Mingjiang; Boswell, H Scott

2018-01-19

Co-occurrence of Flt3ITD and TET2 mutations provoke an animal model of AML by epigenetic repression of Wnt pathway antagonists, including RUNX3, and by hyperexpression of ID1, encoding Wnt agonist. These affect HOXA over-expression and treatment resistance. A comparable epigenetic phenotype was identified among adult AML patients needing novel intervention. We chose combinations of targeted agents acting on distinct effectors, at the levels of both signal transduction and chromatin remodeling, in relapsed/refractory AML's, including Flt3ITD+ve, described with a signature of repressed tumor suppressor genes, involving Wnt antagonist RUNX3 , occurring along with ID1 and HOXA over-expressions. We tracked patient response to combination of Flt3/Raf inhibitor, Sorafenib, and Vorinostat, pan-histone deacetylase inhibitor, without or with added Bortezomib, in consecutive phase I trials. A striking association of rapid objective remissions (near-complete, complete responses) was noted to accompany induced early pharmacodynamic changes within patient blasts in situ, involving these effectors, significantly linking RUNX3 /Wnt antagonist de-repression (80%) and ID1 downregulation (85%), to a response, also preceded by profound HOXA9 repression. Response occurred in context of concurrent TET2 mutation/hypomorphy and Flt3ITD+ve mutation (83% of complete responses). Addition of Bortezomib to the combination was vital to attainment of complete response in Flt3ITD+ve cases exhibiting such Wnt pathway dysregulation.

Human cord blood suppressor T lymphocytes. II. Characterization of inducer of suppressor cells

International Nuclear Information System (INIS)

Cheng, H.; Delespesse, G.

1986-01-01

Previously, we reported an antigen nonspecific inducer of T suppressor cell factor (TisF) produced by cord blood mononuclear cells (MNC) in 48-hr, two-way mixed lymphocyte cultures (MLC). The target of this factor was a radiosensitive, T4+ (T8-) adult suppressor T cell subset. The cellular origin of this TisF was examined in the present study. IgG production by pokeweed mitogen (PWM)-stimulated adult MNC was used as an assay for TisF activity. It was found that TisF-producing cells formed rosettes with sheep erythrocytes (E+) and were independent of adherent cells (AC) in the production of TisF. They were resistant to irradiation (2500 rads) and phenotypic characterization with T cell reactive monoclonal antibodies indicated that they resided in the T8- (T4+) population. Furthermore, both TQ1- and TQ1+ cells were required for the production of TisF activity and such activity could not be reconstituted by supernatants from TQ1- MLC and TQ1+ MLC. These results indicate that the production of TisF is dependent upon interactions between radioresistant E+, T8-, TQ1- and radioresistant E+, T8-, TQ1+ cells

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.

Power consumption in positive ion beam converter with electrostatic electron suppressor

International Nuclear Information System (INIS)

Hashimoto, Kiyoshi; Sugawara, Tohru

1985-01-01

The power recovery characteristics of an in-line direct beam converter provided with electrostatic electron suppressor were studied numerically by tracing the orbits of fast primary ions and secondary charged particles generated along their beam path by collision with background gas molecules. It is shown that, in reference to the electrostatic field potential at the point of impact, the energy distribution of secondary ions impinging on the suppressor has two peaks-one corresponding to a zone of high positive potential surrounding the collector and the other to one of slightly negative potential around the electron suppressor. Secondary electron emission from the suppressor is ascribed mainly to the latter peak, associated with impingement of slower secondary ions. Far much power consumed in secondary particle acceleration is spent for emitting electrons from the suppressor than for secondary ions generated by beam-gas collision. The upper limit of background pressure is discussed on the basis of criteria prescribed for restricting the power consumed in this secondary particle acceleration, as for practical convenience of electrode cooling. Numerical examples are given of calculations based on particle trajectory analysis of both primary ions and secondary particles, for the case of a 100 keV-proton sheet beam 10 cm thick of 35 mA/cm 2 current density. (author)

Axl acts as a tumor suppressor by regulating LIGHT expression in T lymphoma

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Young, Kon-Ji; Park, A-Reum; Choi, Ha-Rim; Lee, Hwa-Youn; Kim, Su-Man; Chung, Byung Yeoup; Park, Chul-Hong; Choi, Hyo Jin; Ko, Young-Hyeh; Bai, Hyoung-Woo; Kang, Hyung-Sik

2017-01-01

Axl is an oncogenic receptor tyrosine kinase that plays a role in many cancers. LIGHT (Lymphotoxin-related inducible ligand that competes for glycoprotein D binding to herpesvirus entry mediator on T cells) is a ligand that induces robust anti-tumor immunity by enhancing the recruitment and activation of effector immune cells at tumor sites. We observed that mouse EL4 and human Jurkat T lymphoma cells that stably overexpressed Axl also showed high expression of LIGHT. When Jurkat-Axl cells were treated with Gas6, a ligand for Axl, LIGHT expression was upregulated through activation of the PI3K/AKT signaling pathway and transcriptional induction by Sp1. The lytic activity of cytotoxic T lymphocytes and natural killer cells was enhanced by EL4-Axl cells. In addition, tumor volume and growth were markedly reduced due to enhanced apoptotic cell death in EL4-Axl tumor-bearing mice as compared to control mice. We also observed upregulated expression of CCL5 and its receptor, CCR5, and enhanced intratumoral infiltration of cytotoxic T lymphocytes and natural killer cells in EL4-Axl-bearing mice as compared to mock controls. These data strongly suggested that Axl exerts novel tumor suppressor effects by inducing upregulation of LIGHT in the tumor microenvironment of T lymphoma. PMID:28423548

Loss of function of Saccharomyces cerevisiae kinesin-related CIN8 and KIP1 is suppressed by KAR3 motor domain mutations.

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Hoyt, M A; He, L; Totis, L; Saunders, W S

1993-09-01

The kinesin-related products of the CIN8 and KIP1 genes of Saccharomyces cerevisiae redundantly perform an essential function in mitosis. The action of either gene-product is required for an outwardly directed force that acts upon the spindle poles. We have selected mutations that suppress the temperature-sensitivity of a cin8-temperature-sensitive kip1-delta strain. The extragenic suppressors analyzed were all found to be alleles of the KAR3 gene. KAR3 encodes a distinct kinesin-related protein whose action antagonizes Cin8p/Kip1p function. All seven alleles analyzed were altered within the region of KAR3 that encodes the putative force-generating (or "motor") domain. These mutations also suppressed the inviability associated with the cin8-delta kip1-delta genotype, a property not shared by a deletion of KAR3. Other properties of the suppressing alleles revealed that they were not null for function. Six of the seven were unaffected for the essential karyogamy and meiosis properties of KAR3 and the seventh was dominant for the suppressing trait. Our findings suggest that despite an antagonistic relationship between Cin8p/Kip1p and Kar3p, aspects of their mitotic roles may be similar.

USP7 Is a Tumor-Specific WNT Activator for APC-Mutated Colorectal Cancer by Mediating β-Catenin Deubiquitination

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Laura Novellasdemunt

2017-10-01

Full Text Available The tumor suppressor gene adenomatous polyposis coli (APC is mutated in most colorectal cancers (CRCs, resulting in constitutive Wnt activation. To understand the Wnt-activating mechanism of the APC mutation, we applied CRISPR/Cas9 technology to engineer various APC-truncated isogenic lines. We find that the β-catenin inhibitory domain (CID in APC represents the threshold for pathological levels of Wnt activation and tumor transformation. Mechanistically, CID-deleted APC truncation promotes β-catenin deubiquitination through reverse binding of β-TrCP and USP7 to the destruction complex. USP7 depletion in APC-mutated CRC inhibits Wnt activation by restoring β-catenin ubiquitination, drives differentiation, and suppresses xenograft tumor growth. Finally, the Wnt-activating role of USP7 is specific to APC mutations; thus, it can be used as a tumor-specific therapeutic target for most CRCs.

Molecular markers for diagnostic cytology of neoplasms in the head region of the pancreas: mutation of K-ras and overexpression of the p53 protein product

NARCIS (Netherlands)

van Es, J. M.; Polak, M. M.; van den Berg, F. M.; Ramsoekh, T. B.; Craanen, M. E.; Hruban, R. H.; Offerhaus, G. J.

1995-01-01

To determine the potential efficiency of molecular markers specific for neoplastic change--mutations of the K-ras oncogene and the p53 tumour suppressor gene--in diagnosing pancreatic carcinoma. Archival cytology samples obtained from 17 patients with established pancreatic carcinoma were assayed

Frequency of Somatic TP53 Mutations in Combination with Known Pathogenic Mutations in Colon Adenocarcinoma, Non–Small Cell Lung Carcinoma, and Gliomas as Identified by Next-Generation Sequencing

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Zahra Shajani-Yi

2018-03-01

Full Text Available The tumor suppressor gene TP53 is the most frequently mutated gene in human cancer. It encodes p53, a DNA-binding transcription factor that regulates multiple genes involved in DNA repair, metabolism, cell cycle arrest, apoptosis, and senescence. TP53 is associated with human cancer by mutations that lead to a loss of wild-type p53 function as well as mutations that confer alternate oncogenic functions that enable them to promote invasion, metastasis, proliferation, and cell survival. Identifying the discrete TP53 mutations in tumor cells may help direct therapies that are more effective. In this study, we identified the frequency of individual TP53 mutations in patients with colon adenocarcinoma (48%, non–small cell lung carcinoma (NSCLC (36%, and glioma/glioblastoma (28% at our institution using next-generation sequencing. We also identified the occurrence of somatic mutations in numerous actionable genes including BRAF, EGFR, KRAS, IDH1, and PIK3CA that occurred concurrently with these TP53 mutations. Of the 480 tumors examined that contained one or more mutations in the TP53 gene, 219 were colon adenocarcinomas, 215 were NSCLCs, and 46 were gliomas/glioblastomas. Among the patients positive for TP53 mutations diagnosed with colon adenocarcinoma, 50% also showed at least one mutation in pathogenic genes of which 14% were BRAF, 33% were KRAS, and 3% were NRAS. Forty-seven percent of NSCLC patients harboring TP53 mutations also had a mutation in at least one actionable pathogenic variant with the following frequencies: BRAF: 4%, EGFR: 10%, KRAS: 28%, and PIK3CA: 4%. Fifty-two percent of patients diagnosed with glioma/glioblastoma with a positive TP53 mutation had at least one concurrent mutation in a known pathogenic gene of which 9% were CDKN2A, 41% were IDH1, and 11% were PIK3CA.

Apparent directional selection by biased pleiotropic mutation.

Science.gov (United States)

Tanaka, Yoshinari

2010-07-01

Pleiotropic effects of deleterious mutations are considered to be among the factors responsible for genetic constraints on evolution by long-term directional selection acting on a quantitative trait. If pleiotropic phenotypic effects are biased in a particular direction, mutations generate apparent directional selection, which refers to the covariance between fitness and the trait owing to a linear association between the number of mutations possessed by individuals and the genotypic values of the trait. The present analysis has shown how the equilibrium mean value of the trait is determined by a balance between directional selection and biased pleiotropic mutations. Assuming that genes act additively both on the trait and on fitness, the total variance-standardized directional selection gradient was decomposed into apparent and true components. Experimental data on mutation bias from the bristle traits of Drosophila and life history traits of Daphnia suggest that apparent selection explains a small but significant fraction of directional selection pressure that is observed in nature; the data suggest that changes induced in a trait by biased pleiotropic mutation (i.e., by apparent directional selection) are easily compensated for by (true) directional selection.

Mutations in the DNA-binding domain of NR2E3 affect in vivo dimerization and interaction with CRX.

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Raphael Roduit

Full Text Available BACKGROUND: NR2E3 (PNR is an orphan nuclear receptor essential for proper photoreceptor determination and differentiation. In humans, mutations in NR2E3 have been associated with the recessively inherited enhanced short wavelength sensitive (S- cone syndrome (ESCS and, more recently, with autosomal dominant retinitis pigmentosa (adRP. NR2E3 acts as a suppressor of the cone generation program in late mitotic retinal progenitor cells. In adult rod photoreceptors, NR2E3 represses cone-specific gene expression and acts in concert with the transcription factors CRX and NRL to activate rod-specific genes. NR2E3 and CRX have been shown to physically interact in vitro through their respective DNA-binding domains (DBD. The DBD also contributes to homo- and heterodimerization of nuclear receptors. METHODOLOGY/PRINCIPAL FINDINGS: We analyzed NR2E3 homodimerization and NR2E3/CRX complex formation in an in vivo situation by Bioluminescence Resonance Energy Transfer (BRET(2. NR2E3 wild-type protein formed homodimers in transiently transfected HEK293T cells. NR2E3 homodimerization was impaired in presence of disease-causing mutations in the DBD, except for the p.R76Q and p.R104W mutant proteins. Strikingly, the adRP-linked p.G56R mutant protein interacted with CRX with a similar efficiency to that of NR2E3 wild-type and p.R311Q proteins. In contrast, all other NR2E3 DBD-mutant proteins did not interact with CRX. The p.G56R mutant protein was also more effective in abolishing the potentiation of rhodospin gene transactivation by the NR2E3 wild-type protein. In addition, the p.G56R mutant enhanced the transrepression of the M- and S-opsin promoter, while all other NR2E3 DBD-mutants did not. CONCLUSIONS/SIGNIFICANCE: These results suggest different disease mechanisms in adRP- and ESCS-patients carrying NR2E3 mutations. Titration of CRX by the p.G56R mutant protein acting as a repressor in trans may account for the severe clinical phenotype in adRP patients.

Reversion of the Arabidopsis rpn12a-1 exon-trap mutation by an intragenic suppressor that weakens the chimeric 5’ splice site [v2; ref status: indexed, http://f1000r.es/18y

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Jasmina Kurepa

2013-06-01

Full Text Available Background: In the Arabidopsis 26S proteasome mutant rpn12a-1, an exon-trap T-DNA is inserted 531 base pairs downstream of the RPN12a STOP codon. We have previously shown that this insertion activates a STOP codon-associated latent 5' splice site that competes with the polyadenylation signal during processing of the pre-mRNA. As a result of this dual input from splicing and polyadenylation in the rpn12a-1 mutant, two RPN12a transcripts are produced and they encode the wild-type RPN12a and a chimeric RPN12a-NPTII protein. Both proteins form complexes with other proteasome subunits leading to the formation of wild-type and mutant proteasome versions. The net result of this heterogeneity of proteasome particles is a reduction of total cellular proteasome activity. One of the consequences of reduced proteasomal activity is decreased sensitivity to the major plant hormone cytokinin. Methods: We performed ethyl methanesulfonate mutagenesis of rpn12a-1 and isolated revertants with wild-type cytokinin sensitivity. Results: We describe the isolation and analyses of suppressor of rpn12a-1 (sor1. The sor1 mutation is intragenic and located at the fifth position of the chimeric intron. This mutation weakens the activated 5' splice site associated with the STOP codon and tilts the processing of the RPN12a mRNA back towards polyadenylation. Conclusions: These results validate our earlier interpretation of the unusual nature of the rpn12a-1 mutation. Furthermore, the data show that optimal 26S proteasome activity requires RPN12a accumulation beyond a critical threshold. Finally, this finding reinforces our previous conclusion that proteasome function is critical for the cytokinin-dependent regulation of plant growth.

NFκB1 is a suppressor of neutrophil-driven hepatocellular carcinoma

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Wilson, C. L.; Jurk, D.; Fullard, N.; Banks, P.; Page, A.; Luli, S.; Elsharkawy, A. M.; Gieling, R. G.; Chakraborty, J. Bagchi; Fox, C.; Richardson, C.; Callaghan, K.; Blair, G. E.; Fox, N.; Lagnado, A.; Passos, J. F.; Moore, A. J.; Smith, G. R.; Tiniakos, D. G.; Mann, J.; Oakley, F.; Mann, D. A.

2015-04-01

Hepatocellular carcinoma (HCC) develops on the background of chronic hepatitis. Leukocytes found within the HCC microenvironment are implicated as regulators of tumour growth. We show that diethylnitrosamine (DEN)-induced murine HCC is attenuated by antibody-mediated depletion of hepatic neutrophils, the latter stimulating hepatocellular ROS and telomere DNA damage. We additionally report a previously unappreciated tumour suppressor function for hepatocellular nfkb1 operating via p50:p50 dimers and the co-repressor HDAC1. These anti-inflammatory proteins combine to transcriptionally repress hepatic expression of a S100A8/9, CXCL1 and CXCL2 neutrophil chemokine network. Loss of nfkb1 promotes ageing-associated chronic liver disease (CLD), characterized by steatosis, neutrophillia, fibrosis, hepatocyte telomere damage and HCC. Nfkb1S340A/S340Amice carrying a mutation designed to selectively disrupt p50:p50:HDAC1 complexes are more susceptible to HCC; by contrast, mice lacking S100A9 express reduced neutrophil chemokines and are protected from HCC. Inhibiting neutrophil accumulation in CLD or targeting their tumour-promoting activities may offer therapeutic opportunities in HCC.

Condensin II mutation causes T-cell lymphoma through tissue-specific genome instability

Science.gov (United States)

Woodward, Jessica; Taylor, Gillian C.; Soares, Dinesh C.; Boyle, Shelagh; Sie, Daoud; Read, David; Chathoth, Keerthi; Vukovic, Milica; Tarrats, Nuria; Jamieson, David; Campbell, Kirsteen J.; Blyth, Karen; Acosta, Juan Carlos; Ylstra, Bauke; Arends, Mark J.; Kranc, Kamil R.; Jackson, Andrew P.; Bickmore, Wendy A.

2016-01-01

Chromosomal instability is a hallmark of cancer, but mitotic regulators are rarely mutated in tumors. Mutations in the condensin complexes, which restructure chromosomes to facilitate segregation during mitosis, are significantly enriched in cancer genomes, but experimental evidence implicating condensin dysfunction in tumorigenesis is lacking. We report that mice inheriting missense mutations in a condensin II subunit (Caph2nes) develop T-cell lymphoma. Before tumors develop, we found that the same Caph2 mutation impairs ploidy maintenance to a different extent in different hematopoietic cell types, with ploidy most severely perturbed at the CD4+CD8+ T-cell stage from which tumors initiate. Premalignant CD4+CD8+ T cells show persistent catenations during chromosome segregation, triggering DNA damage in diploid daughter cells and elevated ploidy. Genome sequencing revealed that Caph2 single-mutant tumors are near diploid but carry deletions spanning tumor suppressor genes, whereas P53 inactivation allowed Caph2 mutant cells with whole-chromosome gains and structural rearrangements to form highly aggressive disease. Together, our data challenge the view that mitotic chromosome formation is an invariant process during development and provide evidence that defective mitotic chromosome structure can promote tumorigenesis. PMID:27737961

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

2015-01-01

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. DOI: http://dx.doi.org/10.7554/eLife.07702.001 PMID:26575287

Low Prevalence of TP53 Mutations and MDM2 Amplifications in Pediatric Rhabdomyosarcoma

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Simona Ognjanovic

2012-01-01

Full Text Available The tumor suppressor gene TP53 is the most commonly mutated gene in human cancer. The reported prevalence of mutations in rhabdomyosarcoma (RMS varies widely, with recent larger studies suggesting that TP53 mutations in pediatric RMS may be extremely rare. Overexpression of MDM2 also attenuates p53 function. We have performed TP53 mutation/MDM2 amplification analyses in the largest series analyzed thus far, including DNA isolated from 37 alveolar and 38 embryonal RMS tumor samples obtained from the Cooperative Human Tissue Network (CHTN. Available samples were frozen tumor tissues (N=48 and histopathology slides. TP53 mutations in exons 4–9 were analyzed by direct sequencing in all samples, and MDM2 amplification analysis was performed by differential PCR on a subset of 22 samples. We found only one sample (1/75, 1.3% carrying a TP53 mutation at codon 259 (p.D259Y and no MDM2 amplification. Two SNPs in the TP53 pathway, associated with accelerated tumor onset in germline TP53 mutation carriers, (TP53 SNP72 (rs no. 1042522 and MDM2 SNP309 (rs no. 2279744, were not found to confer earlier tumor onset. In conclusion, we confirm the extremely low prevalence of TP53 mutations/MDM2 amplifications in pediatric RMS (1.33% and 0%, respectively. The possible inactivation of p53 function by other mechanisms thus remains to be elucidated.

Somatic INK4a-ARF locus mutations: a significant mechanism of gene inactivation in squamous cell carcinomas of the head and neck.

Science.gov (United States)

Poi, M J; Yen, T; Li, J; Song, H; Lang, J C; Schuller, D E; Pearl, D K; Casto, B C; Tsai, M D; Weghorst, C M

2001-01-01

The INK4a-ARF locus is located on human chromosome 9p21 and is known to encode two functionally distinct tumor-suppressor genes. The p16(INK4a) (p16) tumor-suppressor gene product is a negative regulator of cyclin-dependent kinases 4 and 6, which in turn positively regulate progression of mammalian cells through the cell cycle. The p14(ARF) tumor-suppressor gene product specifically interacts with human double minute 2, leading to the subsequent stabilization of p53 and G(1) arrest. Previous investigations analyzing the p16 gene in squamous cell carcinomas of the head and neck (SCCHNs) have suggested the predominate inactivating events to be homozygous gene deletions and hypermethylation of the p16 promoter. Somatic mutational inactivation of p16 has been reported to be low (0-10%, with a combined incidence of 25 of 279, or 9%) and to play only a minor role in the development of SCCHN. The present study examined whether this particular mechanism of INK4a/ARF inactivation, specifically somatic mutation, has been underestimated in SCCHN by determining the mutational status of the p16 and p14(ARF) genes in 100 primary SCCHNs with the use of polymerase chain reaction technology and a highly sensitive, nonradioactive modification of single-stranded conformational polymorphism (SSCP) analysis termed "cold" SSCP. Exons 1alpha, 1beta, and 2 of INK4a/ARF were amplified using intron-based primers or a combination of intron- and exon-based primers. A total of 27 SCCHNs (27%) exhibited sequence alterations in this locus, 22 (22%) of which were somatic sequence alterations and five (5%) of which were a single polymorphism in codon 148. Of the 22 somatic alterations, 20 (91%) directly or indirectly involved exon 2, and two (9%) were located within exon 1alpha. No mutations were found in exon 1beta. All 22 somatic mutations would be expected to yield altered p16 proteins, but only 15 of them should affect p14(ARF) proteins. Specific somatic alterations included microdeletions or

About hidden influence of predictor variables: Suppressor and mediator variables

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Milovanović Boško

2013-01-01

Full Text Available In this paper procedure for researching hidden influence of predictor variables in regression models and depicting suppressor variables and mediator variables is shown. It is also shown that detection of suppressor variables and mediator variables could provide refined information about the research problem. As an example for applying this procedure, relation between Atlantic atmospheric centers and air temperature and precipitation amount in Serbia is chosen. [Projekat Ministarstva nauke Republike Srbije, br. 47007

[Contact shot from infantry weapons with a flash-suppressor].

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Perdekamp, Markus Grosse; Braunwarth, Roland; Schmidt, Ulrike; Schmidt, Wolfgang; Pollak, Stefan

2003-01-01

The number of reports on contact shots from firearms with a flash suppressor attached to the muzzle is small. On the basis of a case report (suicidal shot to the forehead with a Kalschnikow AKMS 47 assault rifle) the morphological peculiarities (characteristics soot pattern, relatively small powder cavity and only minor skin tears in the presence of a bony support) are presented and the conclusions to be drawn from the findings regarding the flash-suppressor, the shot distance, the angle of the shot and the way of holding the weapon are discussed.

PTEN Sequence Analysis in Endometrial Hyperplasia and Endometrial Carcinoma in Slovak Women

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H. Gbelcová

2015-01-01

Full Text Available Phosphatase and tensin homolog (PTEN is a protein that acts as a tumor suppressor by dephosphorylating the lipid second messenger phosphatidylinositol 3,4,5-trisphosphate. Loss of PTEN function has been implicated in the pathogenesis of a number of different tumors, particularly endometrial carcinoma (ECa. ECa is the most common neoplasia of the female genital tract. Our study evaluates an association between the morphological appearance of endometrial hyperplasia and endometrial carcinoma and the degree of PTEN alterations. A total of 45 endometrial biopsies from Slovak women were included in present study. Formalin-fixed and paraffin-embedded tissue samples with simple hyperplasia (3, complex hyperplasia (5, atypical complex hyperplasia (7, endometrioid carcinomas G1 (20 and G3 (5, and serous carcinoma (5 were evaluated for the presence of mutations in coding regions of PTEN gene, the most frequently mutated tumor suppressor gene in endometrial carcinoma. 75% of the detected mutations were clustered in exons 5 and 8. Out of the 39 mutations detected in 24 cases, 20 were frameshifts and 19 were nonsense, missense, or silent mutations. Some specimens harboured more than one mutation. The results of current study on Slovak women were compared to a previous study performed on Polish population. The two sets of results were similar.

The risk of extinction - the mutational meltdown or the overpopulation

OpenAIRE

Malarz, K.

2006-01-01

The phase diagrams survival-extinction for the Penna model with parameters: (mutations rate)-(birth rate), (mutation rate)-(harmful mutations threshold), (harmful mutation threshold)-(minimal reproduction age) are presented. The extinction phase may be caused by either mutational meltdown or overpopulation. When the Verhulst factor is responsible for removing only newly born babies and does not act on adults the overpopulation is avoided and only genetic factors may lead to species extinction.

The risk of extinction - the mutational meltdown or the overpopulation.

Science.gov (United States)

Malarz, Krzysztof

2007-04-01

The phase diagrams survival-extinction for the Penna model with parameters: (mutations rate)-(birth rate), (mutation rate)-(harmful mutations threshold), (harmful mutation threshold)-(minimal reproduction age) are presented. The extinction phase may be caused by either mutational meltdown or overpopulation. When the Verhulst factor is responsible for removing only newly born babies and does not act on adults the overpopulation is avoided and only genetic factors may lead to species extinction.

Suppressor of Cytokine Signaling (SOCS 5 utilises distinct domains for regulation of JAK1 and interaction with the adaptor protein Shc-1.

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Edmond M Linossi

Full Text Available Suppressor of Cytokine Signaling (SOCS5 is thought to act as a tumour suppressor through negative regulation of JAK/STAT and epidermal growth factor (EGF signaling. However, the mechanism/s by which SOCS5 acts on these two distinct pathways is unclear. We show for the first time that SOCS5 can interact directly with JAK via a unique, conserved region in its N-terminus, which we have termed the JAK interaction region (JIR. Co-expression of SOCS5 was able to specifically reduce JAK1 and JAK2 (but not JAK3 or TYK2 autophosphorylation and this function required both the conserved JIR and additional sequences within the long SOCS5 N-terminal region. We further demonstrate that SOCS5 can directly inhibit JAK1 kinase activity, although its mechanism of action appears distinct from that of SOCS1 and SOCS3. In addition, we identify phosphoTyr317 in Shc-1 as a high-affinity substrate for the SOCS5-SH2 domain and suggest that SOCS5 may negatively regulate EGF and growth factor-driven Shc-1 signaling by binding to this site. These findings suggest that different domains in SOCS5 contribute to two distinct mechanisms for regulation of cytokine and growth factor signaling.

Modulation of allogeneic stimulation in man. I. Characterization of an in vitro induced suppressor macrophage population

International Nuclear Information System (INIS)

Stux, S.V.; Dubey, D.P.; Yunis, E.J.

1981-01-01

Cultured human peripheral blood mononuclear cells suppressed the allogeneic response of fresh autologous lymphocytes. This suppressor activity developed gradually over a period of one week. The cells primarily responsible for this effect were enriched by Ficoll density gradient centrifugation. It was found that the suppressor cell is a large, low density nylon wool adherent, radioresistant, phagocytic, and nonspecific esterase positive mononuclear cell. Moreover, these cells did not form E rosettes and were Fc positive. Electron microscopy confirmed that suppressor cells were macrophage like. Suppressor activity was not due to cytotoxicity, crowding, or steric hinderance by the cultured cells. The suppressor macrophage population did not appear to inhibit the allogeneic response via prostaglandin or arginase release, or interfere with the tritiated thymidine uptake by release of endogenous thymidine. The above system is viewed as an in vitro model of immune regulation by suppressor macrophages, in the context of allogeneic response

Analysis of APC mutation in human ameloblastoma and clinical significance.

Science.gov (United States)

Li, Ning; Liu, Bing; Sui, Chengguang; Jiang, Youhong

2016-01-01

As a highly conserved signaling pathway, Wnt/β-catenin signal transduction pathway plays an important role in many processes. Either in the occurrence or development of tumor, activation of this pathway takes an important place. APC inhibits Wnt/β-catenin pathway to regulate cell proliferation and differentiation. This study aimed to investigate the function of cancer suppressor gene. PCR amplification and sequencing method was used to analyze APC mutations of human clinical specimens. The pathological specimens were collected for PCR and clear electrophoretic bands were obtained after electrophoresis. The gene sequence obtained after purification and sequencing analysis was compared with the known APC gene sequence (NM_000038.5). Base mutations at APC 1543 (T → C), APC-4564 (G → A), APC-5353 (T → G), APC-5550 (T → A) and APC-5969 (G → A) locus existed in 22 (27.5 %), 12 (15 %), 5 (6.25 %), 13 (16.25 %) and 12 patients (15 %), respectively. Gene mutations existed in ameloblastoma, and the mutation loci were 1543 locus (T → C), 4564 locus (G → A), 5353 locus (T → G), 5550 locus (T → A) and 5969 locus (G → A) 15 %, respectively. APC mutation plays a certain role in monitoring the tumor malignant degree as it may indicate the transition process of ameloblastoma malignant phenotype.

Mutation analysis of SDHB and SDHC: novel germline mutations in sporadic head and neck paraganglioma and familial paraganglioma and/or pheochromocytoma

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Wong Nora

2006-01-01

Full Text Available Abstract Background Germline mutations of the SDHD, SDHB and SDHC genes, encoding three of the four subunits of succinate dehydrogenase, are a major cause of hereditary paraganglioma and pheochromocytoma, and demonstrate that these genes are classic tumor suppressors. Succinate dehydrogenase is a heterotetrameric protein complex and a component of both the Krebs cycle and the mitochondrial respiratory chain (succinate:ubiquinone oxidoreductase or complex II. Methods Using conformation sensitive gel electrophoresis (CSGE and direct DNA sequencing to analyse genomic DNA from peripheral blood lymphocytes, here we describe the mutation analysis of the SDHB and SDHC genes in 37 patients with sporadic (i.e. no known family history head and neck paraganglioma and five pheochromocytoma and/or paraganglioma families. Results Two sporadic patients were found to have a SDHB splice site mutation in intron 4, c.423+1G>A, which produces a mis-spliced transcript with a 54 nucleotide deletion, resulting in an 18 amino acid in-frame deletion. A third patient was found to carry the c.214C>T (p.Arg72Cys missense mutation in exon 4 of SDHC, which is situated in a highly conserved protein motif that constitutes the quinone-binding site of the succinate: ubiquinone oxidoreductase (SQR complex in E. coli. Together with our previous results, we found 27 germline mutations of SDH genes in 95 cases (28% of sporadic head and neck paraganglioma. In addition all index patients of five families showing hereditary pheochromocytoma-paraganglioma were found to carry germline mutations of SDHB: four of which were novel, c.343C>T (p.Arg115X, c.141G>A (p.Trp47X, c.281G>A (p.Arg94Lys, and c.653G>C (p.Trp218Ser, and one reported previously, c.136C>T, p.Arg46X. Conclusion In conclusion, these data indicate that germline mutations of SDHB and SDHC play a minor role in sporadic head and neck paraganglioma and further underline the importance of germline SDHB mutations in cases of

Viral RNAi suppressor reversibly binds siRNA to outcompete Dicer and RISC via multiple turnover.

Science.gov (United States)

Rawlings, Renata A; Krishnan, Vishalakshi; Walter, Nils G

2011-04-29

RNA interference is a conserved gene regulatory mechanism employed by most eukaryotes as a key component of their innate immune response to viruses and retrotransposons. During viral infection, the RNase-III-type endonuclease Dicer cleaves viral double-stranded RNA into small interfering RNAs (siRNAs) 21-24 nucleotides in length and helps load them into the RNA-induced silencing complex (RISC) to guide the cleavage of complementary viral RNA. As a countermeasure, many viruses have evolved viral RNA silencing suppressors (RSS) that tightly, and presumably quantitatively, bind siRNAs to thwart RNA-interference-mediated degradation. Viral RSS proteins also act across kingdoms as potential immunosuppressors in gene therapeutic applications. Here we report fluorescence quenching and electrophoretic mobility shift assays that probe siRNA binding by the dimeric RSS p19 from Carnation Italian Ringspot Virus, as well as by human Dicer and RISC assembly complexes. We find that the siRNA:p19 interaction is readily reversible, characterized by rapid binding [(1.69 ± 0.07) × 10(8) M(-)(1) s(-1)] and marked dissociation (k(off)=0.062 ± 0.002 s(-1)). We also observe that p19 efficiently competes with recombinant Dicer and inhibits the formation of RISC-related assembly complexes found in human cell extract. Computational modeling based on these results provides evidence for the transient formation of a ternary complex between siRNA, human Dicer, and p19. An expanded model of RNA silencing indicates that multiple turnover by reversible binding of siRNAs potentiates the efficiency of the suppressor protein. Our predictive model is expected to be applicable to the dosing of p19 as a silencing suppressor in viral gene therapy. Copyright © 2011 Elsevier Ltd. All rights reserved.

Viral RNAi suppressor reversibly binds siRNA to outcompete Dicer and RISC via multiple-turnover

Science.gov (United States)

Rawlings, Renata A.; Krishnan, Vishalakshi; Walter, Nils G.

2011-01-01

RNA interference (RNAi) is a conserved gene regulatory mechanism employed by most eukaryotes as a key component of their innate immune response against viruses and retrotransposons. During viral infection, the RNase III-type endonuclease Dicer cleaves viral double-stranded RNA into small interfering RNAs (siRNAs), 21–24 nucleotides in length, and helps load them into the RNA-induced silencing complex (RISC) to guide cleavage of complementary viral RNA. As a countermeasure, many viruses have evolved viral RNA silencing suppressor (RSS) proteins that tightly, and presumably quantitatively, bind siRNAs to thwart RNAi-mediated degradation. Viral RSS proteins also act across kingdoms as potential immunosuppressors in gene therapeutic applications. Here we report fluorescence quenching and electrophoretic mobility shift assays that probe siRNA binding by the dimeric RSS p19 from Carnation Italian Ringspot Virus (CIRV), as well as by human Dicer and RISC assembly complexes. We find that the siRNA:p19 interaction is readily reversible, characterized by rapid binding ((1.69 ± 0.07)×108 M−1s−1) and marked dissociation (koff = 0.062 ± 0.002 s−1). We also observe that p19 efficiently competes with recombinant Dicer and inhibits formation of RISC-related assembly complexes found in human cell extract. Computational modeling based on these results provides evidence for the transient formation of a ternary complex between siRNA, human Dicer, and p19. An expanded model of RNA silencing indicates that multiple-turnover by reversible binding of siRNAs potentiates the efficiency of the suppressor protein. Our predictive model is expected to be applicable to the dosing of p19 as a silencing suppressor in viral gene therapy. PMID:21354178

Optimization of heteroduplex analysis for the detection of BRCA mutations and SNPs

Directory of Open Access Journals (Sweden)

Lucian Negura

2011-02-01

Full Text Available BRCA1 and BRCA2 are tumour suppressor genes whose mutant phenotypes predispose to breast and ovarian cancer. Screening for mutations in these genes is now standard practice for hereditary breast and ovarian cancer (HBOC cases in Europe, and permits medical follow-up and genetic counselling adapted to the needs of individuals in such families. Currently, most laboratories performing diagnostic analysis of the BRCA genes use PCR of exons and intron-exon boundaries coupled to a pre-screening step to identify anomalous amplicons. The techniques employed for the detection of mutations and SNPs have evolved over time and vary in sensitivity, specificity and cost-effectiveness. As a variant for pre-screening techniques, we chose the recently developed Surveyor® heteroduplex cleavage method as a sensitive and specific technique to reveal anomalous amplicons of the BRCA genes, using only basic laboratory equipment and agarose gel electrophoresis. Here we present the detection of either mutations or SNPs within the BRCA1 exon 7, using heteroduplex analysis (HA by mismatch-specific endonuclease, confirmed by dideoxy sequencing.

Recurrent hyperparathyroidism and a novel nonsense mutation in a patient with hyperparathyriodism-jaw tumor syndrome.

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Abdulla, Amer G; O'Leary, Erin M; Isorena, Jennifer P; Diaz, Miguel Fernando Palma; Yeh, Michael W

2013-01-01

To present the case of a hyperparathyroidism-jaw tumor (HPT-JT) patient with a novel nonsense mutation of the CDC73 gene. We present the case of a patient with a history of three prior maxillectomies and two prior parathyroidectomies who presented with recurrent primary hyperparathyroidism (PHPT). We also briefly review the literature pertaining to HPT-JT. Genetic analysis revealed a novel nonsense mutation (c.85G>T; pGlu29) in exon 1 of CDC73. The patient's son underwent genetic testing for a CDC73 mutation and was found to be negative. HPT-JT is a rare condition characterized by PHPT and benign tumors of the mandible and maxilla. Up to 15% of HPT-JT patients with PHPT have parathyroid carcinoma. HPT-JT is associated with an inactivating mutation of CDC73, a gene that codes for the tumor suppressor protein parafibromin. This report expands our understanding of the genetics underlying this rare disorder and emphasizes the importance of early detection in order to prevent hypercalcemic complications such as parathyroid carcinoma.

USP7 Is a Tumor-Specific WNT Activator for APC-Mutated Colorectal Cancer by Mediating β-Catenin Deubiquitination.

Science.gov (United States)

Novellasdemunt, Laura; Foglizzo, Valentina; Cuadrado, Laura; Antas, Pedro; Kucharska, Anna; Encheva, Vesela; Snijders, Ambrosius P; Li, Vivian S W

2017-10-17

The tumor suppressor gene adenomatous polyposis coli (APC) is mutated in most colorectal cancers (CRCs), resulting in constitutive Wnt activation. To understand the Wnt-activating mechanism of the APC mutation, we applied CRISPR/Cas9 technology to engineer various APC-truncated isogenic lines. We find that the β-catenin inhibitory domain (CID) in APC represents the threshold for pathological levels of Wnt activation and tumor transformation. Mechanistically, CID-deleted APC truncation promotes β-catenin deubiquitination through reverse binding of β-TrCP and USP7 to the destruction complex. USP7 depletion in APC-mutated CRC inhibits Wnt activation by restoring β-catenin ubiquitination, drives differentiation, and suppresses xenograft tumor growth. Finally, the Wnt-activating role of USP7 is specific to APC mutations; thus, it can be used as a tumor-specific therapeutic target for most CRCs. Copyright © 2017 The Francis Crick Institute. Published by Elsevier Inc. All rights reserved.

The tumor suppressors p33ING1 and p33ING2 interact with alien in vivo and enhance alien-mediated gene silencing.

Science.gov (United States)

Fegers, Inga; Kob, Robert; Eckey, Maren; Schmidt, Oliver; Goeman, Frauke; Papaioannou, Maria; Escher, Niko; von Eggeling, Ferdinand; Melle, Christian; Baniahmad, Aria

2007-11-01

The tumor suppressor p33ING1 is involved in DNA repair and cell cycle regulation. Furthermore, p33ING1 is a transcriptional silencer that recognizes the histone mark for trimethylated lysine 4 at histone H3. Interestingly, expression of p33ING1 and p33ING2 is able to induce premature senescence in primary human fibroblasts. The corepressor Alien is involved in gene silencing mediated by selected members of nuclear hormone receptors. In addition, Alien acts as a corepressor for E2F1, a member of the E2F cell cycle regulatory family. Furthermore, recent findings suggest that Alien is complexed with transcription factors participating in DNA repair and chromatin. Here, using a proteomic approach by surface-enhanced laser desorption ionization and mass spectrometry (SELDI-MS) combined with immunological techniques, we show that Alien interacts in vivo with the tumor suppressor p33ING1 as well as with the related tumor suppressor candidate p33ING2. The interaction of Alien with p33ING1 and p33ING2 was confirmed in vitro with GST-pull-down, suggesting a direct binding of Alien to these factors. The binding domain was mapped to a central region of Alien. Functionally, the expression of p33ING1 or p33ING2 enhances the Alien-mediated silencing, suggesting that the interaction plays a role in transcriptional regulation. Thus, the findings suggest that the identified interaction between Alien and the tumor suppressors p33ING1 and p33ING2 reveals a novel cellular protein network.

Combined cytotoxic effects of tumor necrosis factor-alpha with various cytotoxic agents in tumor cell lines that are drug resistant due to mutated p53

NARCIS (Netherlands)

Sleijfer, S; Le, T. K. P.; de Jong, S.; Timmer-Bosscha, H; Withoff, S; Mulder, NH

Several studies suggest that tumor necrosis factor-alpha (TNF) is able to overcome drug resistance in tumors. Whether TNF is able to do so in tumor cell lines that are drug resistant due to a mutation in the tumor suppressor gene p53 is unclear. Therefore, we studied the in vitro cytotoxic effects

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

Association of germline mutation in the PTEN tumour suppressor gene and Proteus and Proteus-like syndromes

NARCIS (Netherlands)

Zhou, X.; Hampel, H.; Thiele, H.; Gorlin, R. J.; Hennekam, R. C.; Parisi, M.; Winter, R. M.; Eng, C.

2001-01-01

The molecular aetiology of Proteus syndrome (PS) remains elusive. Germline mutations in PTEN cause Cowden syndrome and Bannayan-Riley-Ruvalcaba syndrome, which are hereditary hamartoma syndromes. Some features-eg, macrocephaly, lipomatosis, and vascular malformations-can be seen in all three

Nonoverlapping Clinical and Mutational Patterns in Melanomas from the Female Genital Tract and Atypical Genital Nevi.

Science.gov (United States)

Yélamos, Oriol; Merkel, Emily A; Sholl, Lauren Meldi; Zhang, Bin; Amin, Sapna M; Lee, Christina Y; Guitart, Gerta E; Yang, Jingyi; Wenzel, Alexander T; Bunick, Christopher G; Yazdan, Pedram; Choi, Jaehyuk; Gerami, Pedram

2016-09-01

Genital melanomas (GM) are the second most common cancer of the female external genitalia and may be confused with atypical genital nevi (AGN), which exhibit atypical histological features but have benign behavior. In this study, we compared the clinical, histological, and molecular features of 19 GM and 25 AGN. We described chromosomal copy number aberrations and the mutational status of 50 oncogenes and tumor suppressor genes in both groups. Our study showed that a pigmented lesion occurring in mucosal tissue, particularly in postmenopausal women, was more likely to be a melanoma than a nevus. GM had high levels of chromosomal instability, with many copy number aberrations. Furthermore, we found a completely nonoverlapping pattern of oncogenic mutations when comparing GM and AGN. In GM, we report somatic mutations in KIT and TP53. Conversely, AGN had frequent BRAF V600E mutations, which were not seen in any of the GM. Our results show that GM and AGN have distinct clinical and molecular changes and that GM have a different mutational pattern compared with AGN. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

Nonspecific suppressor T cells cause decreased mixed lymphocyte culture reactivity in bone marrow transplant patients

International Nuclear Information System (INIS)

Harada, M.; Ueda, M.; Nakao, S.; Kondo, K.; Odaka, K.; Shiobara, S.; Matsue, K.; Mori, T.; Matsuda, T.

1986-01-01

Decreased reactivity in mixed lymphocyte culture (MLC) was observed in patients within 1 yr after allogeneic and autologous bone marrow transplantation. Suppressor activity of peripheral blood mononuclear cells (PBMC) from transplant patients was studied by adding these cells as modulator cells to a bidirectional MLC with cells from normal individuals. PBMC from transplant patients markedly suppressed MLC reactivity in a dose-dependent manner. Suppressor activity was present in cells forming rosettes with sheep erythrocytes. Treatment of modulator cells with monoclonal antibodies against T cell differentiation antigens (OKT8, OKIa1) and complement completely abolished suppression of MLC. Suppressor activity was unaffected by 30 Gy irradiation. Suppressor activity declined gradually after transplantation and was inversely correlated with MLC reactivity of each patient at a significant level (p less than 0.01). These observations suggest that OKT8+ Ia+ radioresistant suppressor T cells play a role in the development of decreased MLC reactivity observed during the early post-transplant period

The Polerovirus silencing suppressor P0 targets ARGONAUTE proteins for degradation.

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Baumberger, Nicolas; Tsai, Ching-Hsui; Lie, Miranda; Havecker, Ericka; Baulcombe, David C

2007-09-18

Plant and animal viruses encode suppressor proteins of an adaptive immunity mechanism in which viral double-stranded RNA is processed into 21-25 nt short interfering (si)RNAs. The siRNAs guide ARGONAUTE (AGO) proteins so that they target viral RNA. Most viral suppressors bind long dsRNA or siRNAs and thereby prevent production of siRNA or binding of siRNA to AGO. The one exception is the 2b suppressor of Cucumoviruses that binds to and inhibits AGO1. Here we describe a novel suppressor mechanism in which a Polerovirus-encoded F box protein (P0) targets the PAZ motif and its adjacent upstream sequence in AGO1 and mediates its degradation. F box proteins are components of E3 ubiquitin ligase complexes that add polyubiquitin tracts on selected lysine residues and thereby mark a protein for proteasome-mediated degradation. With P0, however, the targeted degradation of AGO is insensitive to inhibition of the proteasome, indicating that the proteasome is not involved. We also show that P0 does not block a mobile signal of silencing, indicating that the signal molecule does not have AGO protein components. The ability of P0 to block silencing without affecting signal movement may contribute to the phloem restriction of viruses in the Polerovirus group.

The essential Escherichia coli msgB gene, a multicopy suppressor of a temperature-sensitive allele of the heat shock gene grpE, is identical to dapE.

OpenAIRE

Wu, B; Georgopoulos, C; Ang, D

1992-01-01

The grpE gene product is one of three Escherichia coli heat shock proteins (DnaK, DnaJ, and GrpE) that are essential for both bacteriophage lambda DNA replication and bacterial growth at all temperatures. In an effort to determine the role of GrpE and to identify other factors that it may interact with, we isolated multicopy suppressors of the grpE280 point mutation, as judged by their ability to reverse the temperature-sensitive phenotype of grpE280. Here we report the characterization of on...

Mutations in the Atp1p and Atp3p subunits of yeast ATP synthase differentially affect respiration and fermentation in Saccharomyces cerevisiae.

Science.gov (United States)

Francis, Brian R; White, Karen H; Thorsness, Peter E

2007-04-01

ATP1-111, a suppressor of the slow-growth phenotype of yme1Delta lacking mitochondrial DNA is due to the substitution of phenylalanine for valine at position 111 of the alpha-subunit of mitochondrial ATP synthase (Atp1p in yeast). The suppressing activity of ATP1-111 requires intact beta (Atp2p) and gamma (Atp3p) subunits of mitochondrial ATP synthase, but not the stator stalk subunits b (Atp4p) and OSCP (Atp5p). ATP1-111 and other similarly suppressing mutations in ATP1 and ATP3 increase the growth rate of wild-type strains lacking mitochondrial DNA. These suppressing mutations decrease the growth rate of yeast containing an intact mitochondrial chromosome on media requiring oxidative phosphorylation, but not when grown on fermentable media. Measurement of chronological aging of yeast in culture reveals that ATP1 and ATP3 suppressor alleles in strains that contain mitochondrial DNA are longer lived than the isogenic wild-type strain. In contrast, the chronological life span of yeast cells lacking mitochondrial DNA and containing these mutations is shorter than that of the isogenic wild-type strain. Spore viability of strains bearing ATP1-111 is reduced compared to wild type, although ATP1-111 enhances the survival of spores that lacked mitochondrial DNA.

DMPD: Regulation of innate immunity by suppressor of cytokine signaling (SOCS)proteins. [Dynamic Macrophage Pathway CSML Database

Lifescience Database Archive (English)

Full Text Available 18406369 Regulation of innate immunity by suppressor of cytokine signaling (SOCS)proteins...svg) (.html) (.csml) Show Regulation of innate immunity by suppressor of cytokine signaling (SOCS)proteins. ...PubmedID 18406369 Title Regulation of innate immunity by suppressor of cytokine signaling (SOCS)proteins

ERF is a Potential ERK Modulated Tumor Suppressor in Prostate Cancer

Science.gov (United States)

2016-10-01

6/27/2016 - 6/27/2019 1.20 calendar Prostate Cancer Foundation (formerly CaP CURE) $ 75,000 Epigenetic ...AWARD NUMBER: W81XWH-15-1-0277 TITLE: ERF is a Potential ERK-Modulated Tumor Suppressor in Prostate Cancer PRINCIPAL INVESTIGATOR: Dr. Rohit...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

ERF is a Potential ERK-Modulated Tumor Suppressor in Prostate Cancer

Science.gov (United States)

2017-10-01

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 2017 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 5c

MUTATIONS OF THE SMARCB1 GENE IN HUMAN CANCERS

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D. S. Mikhaylenko

2016-01-01

Full Text Available In the recent years, the full exome sequencing helped to reveal a  set of mutations in the genes that are not oncogenes or tumor suppressor genes by definition, but play an important role in carcinogenesis and encode proteins involved in chromatin remodeling. Among chromatin remodeling systems, which operate through the ATP-dependent mechanism, the complex SWI/ SNF attracts the great attention. The complex consists of the catalytic ATPase (SMARCA2/4, a group of conservative core subunits (SMARCB1, SMARCC1/2, and variant subunits. Abnormalities in the genes coding for each of these components have been identified as driver mutations in various human tumors. The SMARCB1 gene is of interest for practical oncogenetics, with its typical genotype-phenotype correlations. Germinal inactivating mutations (frameshift insertions/deletions, full deletions of the gene, nonsense mutations lead to development of rhabdoid tumors in the kidneys and the brain in children in their first years of life, or even in utero. These tumors are highly malignant (Rhabdoid Tumor Predisposition Syndrome 1 – RTPS1. If a mutation carrier survives his/hers four years of life without manifestation RTPS1 with a missense mutation or has the mutation in the "hot spot" of the first or the last exon, then he/she will not develop rhabdoid tumors, but after 20 years of life, shwannomatosis may develop as multiple benign tumors of peripheral nerves. Finally, some point mutations in the exons 8–9 can result in Coffin-Siris syndrome characterized by mental retardation and developmental disorders, but no neoplasms. In this regard, rational referral of patients for direct DNA diagnostics of each of the described disease entities plays an important role, based on respective minimal criteria, as well as necessity of further development of NGS technologies (full genome and full exome sequencing that are able to sequence not only individual exons, but all candidate genes of the

RNAi suppressors encoded by pathogenic human viruses

NARCIS (Netherlands)

de Vries, Walter; Berkhout, Ben

2008-01-01

RNA silencing or RNAi interference (RNAi) serves as an innate antiviral mechanism in plants, fungi and animals. Human viruses, like plant viruses, encode suppressor proteins or RNAs that block or modulate the RNAi pathway. This review summarizes the mechanisms by which pathogenic human viruses

Pms2 and uracil-DNA glycosylases act jointly in the mismatch repair pathway to generate Ig gene mutations at A-T base pairs.

Science.gov (United States)

Girelli Zubani, Giulia; Zivojnovic, Marija; De Smet, Annie; Albagli-Curiel, Olivier; Huetz, François; Weill, Jean-Claude; Reynaud, Claude-Agnès; Storck, Sébastien

2017-04-03

During somatic hypermutation (SHM) of immunoglobulin genes, uracils introduced by activation-induced cytidine deaminase are processed by uracil-DNA glycosylase (UNG) and mismatch repair (MMR) pathways to generate mutations at G-C and A-T base pairs, respectively. Paradoxically, the MMR-nicking complex Pms2/Mlh1 is apparently dispensable for A-T mutagenesis. Thus, how detection of U:G mismatches is translated into the single-strand nick required for error-prone synthesis is an open question. One model proposed that UNG could cooperate with MMR by excising a second uracil in the vicinity of the U:G mismatch, but it failed to explain the low impact of UNG inactivation on A-T mutagenesis. In this study, we show that uracils generated in the G1 phase in B cells can generate equal proportions of A-T and G-C mutations, which suggests that UNG and MMR can operate within the same time frame during SHM. Furthermore, we show that Ung -/- Pms2 -/- mice display a 50% reduction in mutations at A-T base pairs and that most remaining mutations at A-T bases depend on two additional uracil glycosylases, thymine-DNA glycosylase and SMUG1. These results demonstrate that Pms2/Mlh1 and multiple uracil glycosylases act jointly, each one with a distinct strand bias, to enlarge the immunoglobulin gene mutation spectrum from G-C to A-T bases. © 2017 Girelli Zubani et al.

Structural stability of human protein tyrosine phosphatase ρ catalytic domain: effect of point mutations.

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Alessandra Pasquo

Full Text Available Protein tyrosine phosphatase ρ (PTPρ belongs to the classical receptor type IIB family of protein tyrosine phosphatase, the most frequently mutated tyrosine phosphatase in human cancer. There are evidences to suggest that PTPρ may act as a tumor suppressor gene and dysregulation of Tyr phosphorylation can be observed in diverse diseases, such as diabetes, immune deficiencies and cancer. PTPρ variants in the catalytic domain have been identified in cancer tissues. These natural variants are nonsynonymous single nucleotide polymorphisms, variations of a single nucleotide occurring in the coding region and leading to amino acid substitutions. In this study we investigated the effect of amino acid substitution on the structural stability and on the activity of the membrane-proximal catalytic domain of PTPρ. We expressed and purified as soluble recombinant proteins some of the mutants of the membrane-proximal catalytic domain of PTPρ identified in colorectal cancer and in the single nucleotide polymorphisms database. The mutants show a decreased thermal and thermodynamic stability and decreased activation energy relative to phosphatase activity, when compared to wild- type. All the variants show three-state equilibrium unfolding transitions similar to that of the wild- type, with the accumulation of a folding intermediate populated at ~4.0 M urea.

Multielement suppressor nozzles for thrust augmentation systems.

Science.gov (United States)

Lawrence, R. L.; O'Keefe, J. V.; Tate, R. B.

1972-01-01

The noise reduction and nozzle performance characteristics of large-scale, high-aspect-ratio multielement nozzle arrays operated at low velocities were determined by test. The nozzles are selected for application to high-aspect-ratio augmentor suppressors to be used for augmentor wing airplanes. Significant improvements in noise characteristics for multielement nozzles over those of round or high-aspect-ratio slot nozzles are obtained. Elliptical noise patterns typical of slot nozzles are presented for high-aspect-ratio multielement nozzle arrays. Additional advantages are available in OASPL noise reduction from the element size and spacing. Augmentor-suppressor systems can be designed for maximum beam pattern directivity and frequency spectrum shaping advantages. Measurements of the nozzle wakes show a correlation with noise level data and frequency spectrum peaks. The noise and jet wake results are compared with existing prediction procedures based on empirical jet flow equations, Lighthill relationships, Strouhal number, and empirical shock-induced screech noise effects.

Mutations in LRRC50 predispose zebrafish and humans to seminomas.

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Sander G Basten

2013-04-01

Full Text Available Seminoma is a subclass of human testicular germ cell tumors (TGCT, the most frequently observed cancer in young men with a rising incidence. Here we describe the identification of a novel gene predisposing specifically to seminoma formation in a vertebrate model organism. Zebrafish carrying a heterozygous nonsense mutation in Leucine-Rich Repeat Containing protein 50 (lrrc50 also called dnaaf1, associated previously with ciliary function, are found to be highly susceptible to the formation of seminomas. Genotyping of these zebrafish tumors shows loss of heterozygosity (LOH of the wild-type lrrc50 allele in 44.4% of tumor samples, correlating with tumor progression. In humans we identified heterozygous germline LRRC50 mutations in two different pedigrees with a family history of seminomas, resulting in a nonsense Arg488* change and a missense Thr590Met change, which show reduced expression of the wild-type allele in seminomas. Zebrafish in vivo complementation studies indicate the Thr590Met to be a loss-of-function mutation. Moreover, we show that a pathogenic Gln307Glu change is significantly enriched in individuals with seminoma tumors (13% of our cohort. Together, our study introduces an animal model for seminoma and suggests LRRC50 to be a novel tumor suppressor implicated in human seminoma pathogenesis.

The Heterologous Expression of the p22 RNA Silencing Suppressor of the Crinivirus Tomato Chlorosis Virus from Tobacco Rattle Virus and Potato Virus X Enhances Disease Severity but Does Not Complement Suppressor-Defective Mutant Viruses.

Science.gov (United States)

Landeo-Ríos, Yazmín; Navas-Castillo, Jesús; Moriones, Enrique; Cañizares, M. Carmen

2017-11-24

To counteract host antiviral RNA silencing, plant viruses express suppressor proteins that function as pathogenicity enhancers. The genome of the Tomato chlorosis virus (ToCV) (genus Crinivirus , family Closteroviridae ) encodes an RNA silencing suppressor, the protein p22, that has been described as having one of the longest lasting local suppressor activities when assayed in Nicotiana benthamiana . Since suppression of RNA silencing and the ability to enhance disease severity are closely associated, we analyzed the effect of expressing p22 in heterologous viral contexts. Thus, we studied the effect of the expression of ToCV p22 from viral vectors Tobacco rattle virus (TRV) and Potato virus X (PVX), and from attenuated suppressor mutants in N. benthamiana plants. Our results show that although an exacerbation of disease symptoms leading to plant death was observed in the heterologous expression of ToCV p22 from both viruses, only in the case of TRV did increased viral accumulation occur. The heterologous expression of ToCV p22 could not complement suppressor-defective mutant viruses.

Supervised learning classification models for prediction of plant virus encoded RNA silencing suppressors.

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Zeenia Jagga

Full Text Available Viral encoded RNA silencing suppressor proteins interfere with the host RNA silencing machinery, facilitating viral infection by evading host immunity. In plant hosts, the viral proteins have several basic science implications and biotechnology applications. However in silico identification of these proteins is limited by their high sequence diversity. In this study we developed supervised learning based classification models for plant viral RNA silencing suppressor proteins in plant viruses. We developed four classifiers based on supervised learning algorithms: J48, Random Forest, LibSVM and Naïve Bayes algorithms, with enriched model learning by correlation based feature selection. Structural and physicochemical features calculated for experimentally verified primary protein sequences were used to train the classifiers. The training features include amino acid composition; auto correlation coefficients; composition, transition, and distribution of various physicochemical properties; and pseudo amino acid composition. Performance analysis of predictive models based on 10 fold cross-validation and independent data testing revealed that the Random Forest based model was the best and achieved 86.11% overall accuracy and 86.22% balanced accuracy with a remarkably high area under the Receivers Operating Characteristic curve of 0.95 to predict viral RNA silencing suppressor proteins. The prediction models for plant viral RNA silencing suppressors can potentially aid identification of novel viral RNA silencing suppressors, which will provide valuable insights into the mechanism of RNA silencing and could be further explored as potential targets for designing novel antiviral therapeutics. Also, the key subset of identified optimal features may help in determining compositional patterns in the viral proteins which are important determinants for RNA silencing suppressor activities. The best prediction model developed in the study is available as a

Profiling of oligosaccharides and p53 gene mutation in Filipino breast tumors

International Nuclear Information System (INIS)

Deocaris, Custer C.; De Vera, Azucena C.; Magno, Jose Donato A.; Cruz, Michael Joseph B.; Prodigalidad, Abelardo-Alan T.; Jacinto, Sonia D.

2010-01-01

Majority of patients are diagnosed with benign tumors, however, such benign tumors can progress to an invasive disease. Since carbohydrate-mediated cell-cell adhesion and proliferative potential play crucial roles in tumorigenesis and tumor aggressive behavior, we analyzed the qualitative changes in oligosaccharide expression and analyzed for presence of mutation in the tumor suppressor p53 gene, the most mutated gene in all human cancers. Forty-three (43) breast tumors were screened for p53 mutation in exons 2-11 using polymerase chain reaction (PCR)-amplification coupled to temporal temperature gradient electrophoresis (TTGE). Paraffin-embedded tissues were stained with biotinylated-glycoproteins containing the following sugar groups: mannose (Man), lactose (Lac), fucoidan (Fuc), N-acetyl-glucosamine (GlcNac), N-acetyl-b-galactosamine (GalNAc) and hyaluronic acid (Hya). Expression of carbohydrate receptors was significantly elevated (p=0.003) in malignant compared with benign tumors, particularly at receptors for GalNAc, lac and Fuc. No change in overall glycan signatures using our panel of neoglycoconjugates was noted when grouped according to p53 mutation status in both benign and malignant cases. Although the prognostic value of carbohydrate-receptors in breast cancer has not been validated to date, our results indicate that benign and malignant tumors can be defined by their affinities to our battery of neoglyconjugates. However, result from our reverse lectin histochemistry failed to correlated glycan signature with presence of p53 mutations. (author)

Suppressor Effects of Positive and Negative Religious Coping on Academic Burnout Among Korean Middle School Students.

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Noh, Hyunkyung; Chang, Eunbi; Jang, Yoojin; Lee, Ji Hae; Lee, Sang Min

2016-02-01

Statistical suppressor effects in prediction models can provide evidence of the interdependent relationship of independent variables. In this study, the suppressor effects of positive and negative religious coping on academic burnout were examined using longitudinal data. First, 388 middle school students reported their type of religion and use of positive and negative religious coping strategies. Four months later, they also reported their level of academic burnout. From structural equation modeling, significant suppressor effects were found among religious students. That is, the coefficients became larger when both positive and negative religious coping predicted academic burnout simultaneously, compared to when each religious coping predicted academic burnout alone. However, suppressor effects were not found among non-religious students.

Kinetics of mutation induction by ultraviolet light in excision-deficient yeast.

Science.gov (United States)

Eckardt, F; Haynes, R H

1977-02-01

We have measured the frequency of UV-induced reversions (locus plus suppressor) for the ochre alleles ade2-1 and lys2-1 and forward mutations (ade2 adex double auxotrophs) in an excision-deficient strain of Saccharomyces cerevisiae (rad2-20). For very low UV doses, both mutational systems exhibit linear induction kinetics. However, as the dose increases, a strikingly different response is observed: in the selective reversion system a transition to higher order induction kinetics occurs near 9 ergs/mm2 (25% survival), whereas in the nonselective forward system the mutation frequency passes through a maximum near 14 ergs/mm2 (4.4% survival) and then declines. This contrast in kinetics cannot be explained in any straightforward way by current models of induced mutagenesis, which have been developed primarily on the basis of bacterial data. The bacterial models are designed to accommodate the quadratic induction kinetics that are frequently observed in these systems. We have derived a mathematical expression for mutation frequency that enables us to fit both the forward and reversion data on the assumptions that mutagenesis is basically a "single event" Poisson process, and that mutation and killing are not necessarily independent of one another. In particular, the dose-response relations are consistent with the idea that the sensitivity of the revertants is about 25% less than that of the original cell population, whereas the sensitivity of the forward mutants is about 29% greater than the population average. We argue that this relatively small differential sensitivity of mutant and nonmutant cells is associated with events that take place during mutation expression and clonal growth.

Kinetics of mutation induction by ultraviolet light in excision-deficient yeast

International Nuclear Information System (INIS)

Eckardt, F.; Haynes, R.H.

1977-01-01

We have measured the frequency of uv-induced reversions (locus plus suppressor) for the ochre alleles ade 2-1 and lys 2-1 and forward mutations (ade2 adex double auxotrophs) in an excision-deficient strain of Saccharomyces cerevisiae (rad 2-20). For very low uv doses, both mutational systems exhibit linear induction kinetics. However, as the dose increases, a strikingly different response is observed: in the selective reversion system a transition to higher order induction kinetics occurs near 9 ergs/mm 2 (25 percent survival), whereas in the nonselective forward system the mutation frequency passes through a maximum near 14 ergs/mm 2 (4.4 percent survival) and then declines. This contrast in kinetics cannot be explained in any straightforward way by current models of induced mutagenesis, which have been developed primarily on the basis of bacterial data. The bacterial models are designed to accommodate the quadratic induction kinetics that are frequently observed in these systems. We have derived a mathematical expression for mutation frequency that enables us to fit both the forward and reversion data on the assumptions that mutagenesis is basically a ''single event'' Poisson process, and that mutation and killing are not necessarily independent of one another. In particular, the dose-response relations are consistent with the idea that the sensitivity of the revertants is about 25 percent less than that of the original cell population, whereas the sensitivity of the forward mutants is about 29 percent greater than the population average. We argue that this relatively small differential sensitivity of mutant and nonmutant cells is associated with events that take place during mutation expression and clonal growth

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

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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.

Chloroplast mutations induced by 9-aminoacridine hydrochloride are independent of the plastome mutator in Oenothera.

Science.gov (United States)

GuhaMajumdar, M; Baldwin, S; Sears, B B

2004-02-01

Oenothera plants homozygous for the recessive plastome mutator allele ( pm) show chloroplast DNA (cpDNA) mutation frequencies that are about 1,000-fold higher than spontaneous levels. The pm-encoded gene product has been hypothesized to have a function in cpDNA replication, repair and/or mutation avoidance. Previous chemical mutagenesis experiments with the alkylating agent nitroso-methyl urea (NMU) showed a synergistic effect of NMU on the induction of mutations in the pm line, suggesting an interaction between the pm-encoded gene product and one of the repair systems that corrects alkylation damage. The goal of the experiments described here was to examine whether the pm activity extends to the repair of damage caused by non-alkylating mutagens. To this end, the intercalating mutagen, 9-aminoacridine hydrochloride (9AA) was tested for synergism with the plastome mutator. A statistical analysis of the data reported here indicates that the pm-encoded gene product is not involved in the repair of the 9AA-induced mutations. However, the recovery of chlorotic sectors in plants derived from the mutagenized seeds shows that 9AA can act as a mutagen of the chloroplast genome.

Functional Crosstalk between the PP2A and SUMO Pathways Revealed by Analysis of STUbL Suppressor, razor 1-1.

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Minghua Nie

2016-07-01

Full Text Available Posttranslational modifications (PTMs provide dynamic regulation of the cellular proteome, which is critical for both normal cell growth and for orchestrating rapid responses to environmental stresses, e.g. genotoxins. Key PTMs include ubiquitin, the Small Ubiquitin-like MOdifier SUMO, and phosphorylation. Recently, SUMO-targeted ubiquitin ligases (STUbLs were found to integrate signaling through the SUMO and ubiquitin pathways. In general, STUbLs are recruited to target proteins decorated with poly-SUMO chains to ubiquitinate them and drive either their extraction from protein complexes, and/or their degradation at the proteasome. In fission yeast, reducing or preventing the formation of SUMO chains can circumvent the essential and DNA damage response functions of STUbL. This result indicates that whilst some STUbL "targets" have been identified, the crucial function of STUbL is to antagonize SUMO chain formation. Herein, by screening for additional STUbL suppressors, we reveal crosstalk between the serine/threonine phosphatase PP2A-Pab1B55 and the SUMO pathway. A hypomorphic Pab1B55 mutant not only suppresses STUbL dysfunction, but also mitigates the phenotypes associated with deletion of the SUMO protease Ulp2, or mutation of the STUbL cofactor Rad60. Together, our results reveal a novel role for PP2A-Pab1B55 in modulating SUMO pathway output, acting in parallel to known critical regulators of SUMOylation homeostasis. Given the broad evolutionary functional conservation of the PP2A and SUMO pathways, our results could be relevant to the ongoing attempts to therapeutically target these factors.

Resistance to EGF receptor inhibitors in glioblastoma mediated by phosphorylation of the PTEN tumor suppressor at tyrosine 240.

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Fenton, Tim R; Nathanson, David; Ponte de Albuquerque, Claudio; Kuga, Daisuke; Iwanami, Akio; Dang, Julie; Yang, Huijun; Tanaka, Kazuhiro; Oba-Shinjo, Sueli Mieko; Uno, Miyuki; Inda, Maria del Mar; Wykosky, Jill; Bachoo, Robert M; James, C David; DePinho, Ronald A; Vandenberg, Scott R; Zhou, Huilin; Marie, Suely K N; Mischel, Paul S; Cavenee, Webster K; Furnari, Frank B

2012-08-28

Glioblastoma multiforme (GBM) is the most aggressive of the astrocytic malignancies and the most common intracranial tumor in adults. Although the epidermal growth factor receptor (EGFR) is overexpressed and/or mutated in at least 50% of GBM cases and is required for tumor maintenance in animal models, EGFR inhibitors have thus far failed to deliver significant responses in GBM patients. One inherent resistance mechanism in GBM is the coactivation of multiple receptor tyrosine kinases, which generates redundancy in activation of phosphoinositide-3'-kinase (PI3K) signaling. Here we demonstrate that the phosphatase and tensin homolog deleted on chromosome 10 (PTEN) tumor suppressor is frequently phosphorylated at a conserved tyrosine residue, Y240, in GBM clinical samples. Phosphorylation of Y240 is associated with shortened overall survival and resistance to EGFR inhibitor therapy in GBM patients and plays an active role in mediating resistance to EGFR inhibition in vitro. Y240 phosphorylation can be mediated by both fibroblast growth factor receptors and SRC family kinases (SFKs) but does not affect the ability of PTEN to antagonize PI3K signaling. These findings show that, in addition to genetic loss and mutation of PTEN, its modulation by tyrosine phosphorylation has important implications for the development and treatment of GBM.

The FH mutation database: an online database of fumarate hydratase mutations involved in the MCUL (HLRCC tumor syndrome and congenital fumarase deficiency

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Tomlinson Ian PM

2008-03-01

Full Text Available Abstract Background Fumarate hydratase (HGNC approved gene symbol – FH, also known as fumarase, is an enzyme of the tricarboxylic acid (TCA cycle, involved in fundamental cellular energy production. First described by Zinn et al in 1986, deficiency of FH results in early onset, severe encephalopathy. In 2002, the Multiple Leiomyoma Consortium identified heterozygous germline mutations of FH in patients with multiple cutaneous and uterine leiomyomas, (MCUL: OMIM 150800. In some families renal cell cancer also forms a component of the complex and as such has been described as hereditary leiomyomatosis and renal cell cancer (HLRCC: OMIM 605839. The identification of FH as a tumor suppressor was an unexpected finding and following the identification of subunits of succinate dehydrogenase in 2000 and 2001, was only the second description of the involvement of an enzyme of intermediary metabolism in tumorigenesis. Description The FH mutation database is a part of the TCA cycle gene mutation database (formerly the succinate dehydrogenase gene mutation database and is based on the Leiden Open (source Variation Database (LOVD system. The variants included in the database were derived from the published literature and annotated to conform to current mutation nomenclature. The FH database applies HGVS nomenclature guidelines, and will assist researchers in applying these guidelines when directly submitting new sequence variants online. Since the first molecular characterization of an FH mutation by Bourgeron et al in 1994, a series of reports of both FH deficiency patients and patients with MCUL/HLRRC have described 107 variants, of which 93 are thought to be pathogenic. The most common type of mutation is missense (57%, followed by frameshifts & nonsense (27%, and diverse deletions, insertions and duplications. Here we introduce an online database detailing all reported FH sequence variants. Conclusion The FH mutation database strives to systematically

Revertant mutation releases confined lethal mutation, opening Pandora's box: a novel genetic pathogenesis.

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Yasushi Ogawa

2014-05-01

Full Text Available When two mutations, one dominant pathogenic and the other "confining" nonsense, coexist in the same allele, theoretically, reversion of the latter may elicit a disease, like the opening of Pandora's box. However, cases of this hypothetical pathogenic mechanism have never been reported. We describe a lethal form of keratitis-ichthyosis-deafness (KID syndrome caused by the reversion of the GJB2 nonsense mutation p.Tyr136X that would otherwise have confined the effect of another dominant lethal mutation, p.Gly45Glu, in the same allele. The patient's mother had the identical misssense mutation which was confined by the nonsense mutation. The biological relationship between the parents and the child was confirmed by genotyping of 15 short tandem repeat loci. Haplotype analysis using 40 SNPs spanning the >39 kbp region surrounding the GJB2 gene and an extended SNP microarray analysis spanning 83,483 SNPs throughout chromosome 13 in the family showed that an allelic recombination event involving the maternal allele carrying the mutations generated the pathogenic allele unique to the patient, although the possibility of coincidental accumulation of spontaneous point mutations cannot be completely excluded. Previous reports and our mutation screening support that p.Gly45Glu is in complete linkage disequilibrium with p.Tyr136X in the Japanese population. Estimated from statisitics in the literature, there may be approximately 11,000 p.Gly45Glu carriers in the Japanese population who have this second-site confining mutation, which acts as natural genetic protection from the lethal disease. The reversion-triggered onset of the disesase shown in this study is a previously unreported genetic pathogenesis based on Mendelian inheritance.

Viral suppression of multiple escape mutants by de novo CD8+ T cell responses in a human immunodeficiency virus-1 Infected elite suppressor

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Siliciano Robert F

2011-08-01

Full Text Available Abstract Elite suppressors or controllers (ES are HIV-1 infected patients who maintain undetectable viral loads without treatment. While HLA-B*57-positive ES are usually infected with virus that is unmutated at CTL epitopes, a single, dominant variant containing CTL escape mutations is typically seen in plasma during chronic infection. We describe an ES who developed seven distinct and rare escape variants at an HLA-B*57-restricted Gag epitope over a five year period. Interestingly, he developed proliferative, de novo CTL responses that suppressed replication of each of these variants. These responses, in combination with low viral fitness of each variant, may contribute to sustained elite control in this ES.

Suppressor cells in transplantation tolerance. III. The role of antigen in the maintenance of transplantation tolerance

International Nuclear Information System (INIS)

Tutschka, P.J.; Hess, A.D.; Beschorner, W.E.; Santos, G.W.

1982-01-01

Suppressor cells, which in an alloantigen-specific manner inhibit proliferation of donor cells to host antigens in a mixed lymphocyte culture and adoptively transfer the suppression of graft-versus-host disease (GVHD), undergo a gradual clonal reduction in long-term, allogeneic, histoincompatible rat radiation chimeras until they can no longer be measured in an in vitro suppressor cell assay. When lymphohematopoietic cells from these chimeras are transferred into lethally irradiated secondary recipients of original donor strain, the suppressor cells, now in a target antigen-free environment, undergo a further clonal reduction. After parking for 120 days, the chimeric cells are specifically tolerant to original host antigens, but cannot adoptively transfer suppression of GVHD. When chimeric cells, parked for 120 days in secondary recipients of original donor strain, are stimulated with original host-type antigen repeatedly during or once at the end of the parking period, the suppressor cell clone is expanded, suppressor cells can be identified in vitro, and suppression of GVHD can adoptively be transferred to tertiary recipients

A Site Specific Model And Analysis Of The Neutral Somatic Mutation Rate In Whole-Genome Cancer Data

DEFF Research Database (Denmark)

Bertl, Johanna; Guo, Qianyun; Rasmussen, Malene Juul

2017-01-01

Detailed modelling of the neutral mutational process in cancer cells is crucial for identifying driver mutations and understanding the mutational mechanisms that act during cancer development. The neutral mutational process is very complex: whole-genome analyses have revealed that the mutation ra...

Tbc1d1 mutation in lean mouse strain confers leanness and protects from diet-induced obesity

DEFF Research Database (Denmark)

Chadt, Alexandra; Leicht, Katja; Deshmukh, Atul

2008-01-01

We previously identified Nob1 as a quantitative trait locus for high-fat diet-induced obesity and diabetes in genome-wide scans of outcross populations of obese and lean mouse strains. Additional crossbreeding experiments indicated that Nob1 represents an obesity suppressor from the lean Swiss Jim...... Lambert (SJL) strain. Here we identify a SJL-specific mutation in the Tbc1d1 gene that results in a truncated protein lacking the TBC Rab-GTPase-activating protein domain. TBC1D1, which has been recently linked to human obesity, is related to the insulin signaling protein AS160 and is predominantly...... and reduced glucose uptake in isolated skeletal muscle. Our data strongly suggest that mutation of Tbc1d1 suppresses high-fat diet-induced obesity by increasing lipid use in skeletal muscle....

Restricted ultraviolet mutational spectrum in a shuttle vector propagated in xeroderma pigmentosum cells

International Nuclear Information System (INIS)

Bredberg, A.; Kraemer, K.H.; Seidman, M.M.

1986-01-01

A shuttle vector plasmid, pZ189, carrying a bacterial suppressor tRNA marker gene, was treated with ultraviolet radiation and propagated in cultured skin cells from a patient with the skin-cancer-prone, DNA repair-deficient disease xeroderma pigmentosum and in repair-proficient cells. After replication in the human cells, progeny plasmids were purified. Plasmid survival and mutations inactivating the marker gene were scored by transforming an indicator strain of Escherichia coli carrying a suppressible amber mutation in the beta-galactosidase gene. Plasmid survival in the xeroderma pigmentosum cells was less than that of pZ189 harvested from repair-proficient human cells. The point-mutation frequency in the 150-base-pair tRNA marker gene increased up to 100-fold with ultraviolet dose. Sequence analysis of 150 mutant plasmids revealed that mutations were infrequent at potential thymine-thymine dimer sites. Ninety-three percent of the mutant plasmids from the xeroderma pigmentosum cells showed G X C----A X T transitions, compared to 73% in the normal cells (P less than 0.002). There were significantly fewer transversions (P less than 0.002) (especially G X C----T X A) and multiple base substitutions (P less than 0.00001) than when pZ189 was passaged in repair-proficient cells. The subset of mutational changes that are common to ultraviolet-treated plasmids propagated in both repair-proficient and xeroderma pigmentosum skin cells may be associated with the development of ultraviolet-induced skin cancer in humans

Mutation and Expression of the DCC Gene in Human Lung Cancer

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Takashi Kohno

2000-07-01

Full Text Available Chromosome 18q is frequently deleted in lung cancers, a common region of 18q deletions was mapped to chromosome 18g21. Since the DCC candidate tumor suppressor gene has been mapped in this region, mutation and expression of the DCC gene were examined in 46 lung cancer cell lines, consisting of 14 small cell lung carcinomas (SCLCs and 32 non-small cell lung carcinomas (NSCLCs, to elucidate the pathogenetic significance of DCC alterations in human lung carcinogenesis. A heterozygous missense mutation was detected in a NSCLC cell line, Ma26, while homozygous deletion was not detected in any of the cell lines. The DCC gene was expressed in 11 (24% of the 46 cell lines, the incidence of DCC expression was significantly higher in SCLCs (7/14, 50% than in NSCLCs (4/32, 13% (P = .01, Fisher's exact test. Therefore, genetic alterations of DCC are infrequent; however, the levels of DCC expression vary among lung cancer cells, in particular, between SCLCs and NSCLCs. The present result does not implicate DCC as a specific mutational target of 18q deletions in human lung cancer; however, it suggests that DCC is a potential target of inactivation by genetic defects including intron or promoter mutations and/or epigenetic alterations. The present result also suggests that DCC expression is associated with some properties of SCLCs, such as a neuroendocrine (NE feature.

Effect of hemopoietic microenvironment on splenic suppressor macrophages in congenitally anemic mice of genotype Sl/Sld

International Nuclear Information System (INIS)

Shibata, Y.; Volkman, A.

1985-01-01

Mechanisms underlying mononuclear phagocyte specialization are being probed by studying suppressor macrophages (M phi) as a reference population in mouse models with impaired blood monocyte formation. Splenic suppressor M phi, defined by PGE-mediated inhibition of Con A-induced T lymphocyte proliferation are induced by the i.p. administration of Corynebacterium parvum (CP). Mice severely depleted of bone marrow and blood monocytes by treatment with 89Sr fail to show this suppressor M phi response to CP, although M phi-forming stem cells, assessed as splenic M-CFC in vitro, are increased 20-fold. These observations suggest that radiosensitive bone marrow stem cells are necessary for the generation of both suppressor M phi and monocytes and that one such stem cell may be common to both types of mononuclear phagocytes. This notion was explored further by employing congenitally anemic mice of the genotype S1/S1d in which the hemopoietic microenvironment is genetically defective and thus unable to support the proliferation, differentiation, and function of stem cells. The congenital defect was found to be additionally expressed in the S1/S1d mouse by a monocytopenia of less than 10% of the values in normal congenic littermate controls and by the failure of splenic M-CFC to increase in response to CP. PGE-producing suppressor M phi expressing Fc gamma 2b receptors, however, were induced by CP in S1/S1d mice with no significant diminution of suppressor activity. These data establish the fact that significant impairment of the formation of monocytes is part of the overall hemopoietic defect in S1/S1d mice. PGE-producing suppressor M phi, however, were inducible at normal functional levels in the presence of a profound monocytopenia, and therefore appear to be independent of the mechanisms that regulate blood monocyte formation

Presence of a consensus DNA motif at nearby DNA sequence of the mutation susceptible CG nucleotides.

Science.gov (United States)

Chowdhury, Kaushik; Kumar, Suresh; Sharma, Tanu; Sharma, Ankit; Bhagat, Meenakshi; Kamai, Asangla; Ford, Bridget M; Asthana, Shailendra; Mandal, Chandi C

2018-01-10

Complexity in tissues affected by cancer arises from somatic mutations and epigenetic modifications in the genome. The mutation susceptible hotspots present within the genome indicate a non-random nature and/or a position specific selection of mutation. An association exists between the occurrence of mutations and epigenetic DNA methylation. This study is primarily aimed at determining mutation status, and identifying a signature for predicting mutation prone zones of tumor suppressor (TS) genes. Nearby sequences from the top five positions having a higher mutation frequency in each gene of 42 TS genes were selected from a cosmic database and were considered as mutation prone zones. The conserved motifs present in the mutation prone DNA fragments were identified. Molecular docking studies were done to determine putative interactions between the identified conserved motifs and enzyme methyltransferase DNMT1. Collective analysis of 42 TS genes found GC as the most commonly replaced and AT as the most commonly formed residues after mutation. Analysis of the top 5 mutated positions of each gene (210 DNA segments for 42 TS genes) identified that CG nucleotides of the amino acid codons (e.g., Arginine) are most susceptible to mutation, and found a consensus DNA "T/AGC/GAGGA/TG" sequence present in these mutation prone DNA segments. Similar to TS genes, analysis of 54 oncogenes not only found CG nucleotides of the amino acid Arg as the most susceptible to mutation, but also identified the presence of similar consensus DNA motifs in the mutation prone DNA fragments (270 DNA segments for 54 oncogenes) of oncogenes. Docking studies depicted that, upon binding of DNMT1 methylates to this consensus DNA motif (C residues of CpG islands), mutation was likely to occur. Thus, this study proposes that DNMT1 mediated methylation in chromosomal DNA may decrease if a foreign DNA segment containing this consensus sequence along with CG nucleotides is exogenously introduced to dividing

Mild and severe cereal yellow dwarf viruses differ in silencing suppressor efficiency of the P0 protein.

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Almasi, Reza; Miller, W Allen; Ziegler-Graff, Véronique

2015-10-02

Viral pathogenicity has often been correlated to the expression of the viral encoded-RNA silencing suppressor protein (SSP). The silencing suppressor activity of the P0 protein encoded by cereal yellow dwarf virus-RPV (CYDV-RPV) and -RPS (CYDV-RPS), two poleroviruses differing in their symptomatology was investigated. CYDV-RPV displays milder symptoms in oat and wheat whereas CYDV-RPS is responsible for more severe disease. We showed that both P0 proteins (P0(CY-RPV) and P0(CY-RPS)) were able to suppress local RNA silencing induced by either sense or inverted repeat transgenes in an Agrobacterium tumefaciens-mediated expression assay in Nicotiana benthamiana. P0(CY-RPS) displayed slightly higher activity. Systemic spread of the silencing signal was not impaired. Analysis of short-interfering RNA (siRNA) abundance revealed that accumulation of primary siRNA was not affected, but secondary siRNA levels were reduced by both CYDV P0 proteins, suggesting that they act downstream of siRNA production. Correlated with this finding we showed that both P0 proteins partially destabilized ARGONAUTE1. Finally both P0(CY-RPV) and P0(CY-RPS) interacted in yeast cells with ASK2, a component of an E3-ubiquitin ligase, with distinct affinities. Copyright © 2015 Elsevier B.V. All rights reserved.

Restorer-of-Fertility Mutations Recovered in Transposon-Active Lines of S Male-Sterile Maize

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Susan Gabay-Laughnan

2018-01-01

Full Text Available Mitochondria execute key pathways of central metabolism and serve as cellular sensing and signaling entities, functions that depend upon interactions between mitochondrial and nuclear genetic systems. This is exemplified in cytoplasmic male sterility type S (CMS-S of Zea mays, where novel mitochondrial open reading frames are associated with a pollen collapse phenotype, but nuclear restorer-of-fertility (restorer mutations rescue pollen function. To better understand these genetic interactions, we screened Activator-Dissociation (Ac-Ds, Enhancer/Suppressor-mutator (En/Spm, and Mutator (Mu transposon-active CMS-S stocks to recover new restorer mutants. The frequency of restorer mutations increased in transposon-active stocks compared to transposon-inactive stocks, but most mutants recovered from Ac-Ds and En/Spm stocks were unstable, reverting upon backcrossing to CMS-S inbred lines. However, 10 independent restorer mutations recovered from CMS-S Mu transposon stocks were stable upon backcrossing. Many restorer mutations condition seed-lethal phenotypes that provide a convenient test for allelism. Eight such mutants recovered in this study included one pair of allelic mutations that were also allelic to the previously described rfl2-1 mutant. Targeted analysis of mitochondrial proteins by immunoblot identified two features that consistently distinguished restored CMS-S pollen from comparably staged, normal-cytoplasm, nonmutant pollen: increased abundance of nuclear-encoded alternative oxidase relative to mitochondria-encoded cytochrome oxidase and decreased abundance of mitochondria-encoded ATP synthase subunit 1 compared to nuclear-encoded ATP synthase subunit 2. CMS-S restorer mutants thus revealed a metabolic plasticity in maize pollen, and further study of these mutants will provide new insights into mitochondrial functions that are critical to pollen and seed development.

Suppressors of RNA silencing encoded by tomato leaf curl ...

Indian Academy of Sciences (India)

2013-01-06

Jan 6, 2013 ... Virus encoded RNA-silencing suppressors (RSSs) are the key components evolved by the viruses to ... severe disease symptom in the host (Briddon et al. ..... Voinnet O 2001 RNA silencing as a plant immune system against.

Potential hot spot for de novo mutations in PTCH1 gene in Gorlin syndrome patients: a case report of twins from Croatia.

Science.gov (United States)

Musani, Vesna; Ozretić, Petar; Trnski, Diana; Sabol, Maja; Poduje, Sanja; Tošić, Mateja; Šitum, Mirna; Levanat, Sonja

2018-02-28

We describe a case of twins with sporadic Gorlin syndrome. Both twins had common Gorlin syndrome features including calcification of the falx cerebri, multiple jaw keratocysts, and multiple basal cell carcinomas, but with different expressivity. One brother also had benign testicular mesothelioma. We propose this tumor type as a possible new feature of Gorlin syndrome. Gorlin syndrome is a rare autosomal dominant disorder characterized by both developmental abnormalities and cancer predisposition, with variable expression of various developmental abnormalities and different types of tumors. The syndrome is primarily caused by mutations in the Patched 1 (PTCH1) gene, although rare mutations of Patched 2 (PTCH2) or Suppressor of Fused (SUFU) genes have also been found. Neither founder mutations nor hot spot locations have been described for PTCH1 in Gorlin syndrome patients. Although de novo mutations of the PTCH1 gene occur in almost 50% of Gorlin syndrome cases, there are a few recurrent mutations. Our twin patients were carriers of a de novo mutation in the PTCH1 gene, c.3364_3365delAT (p.Met1122ValfsX22). This is, to our knowledge, the first Gorlin syndrome-causing mutation that has been reported four independent times in distant geographical locations. Therefore, we propose the location of the described mutation as a potential hot spot for mutations in PTCH1.

Engineered mutations in fibrillin-1 leading to Marfan syndrome act at the protein, cellular and organismal levels.

Science.gov (United States)

Zeyer, Karina A; Reinhardt, Dieter P

2015-01-01

Fibrillins are the major components of microfibrils in the extracellular matrix of elastic and non-elastic tissues. They are multi-domain proteins, containing primarily calcium binding epidermal growth factor-like (cbEGF) domains and 8-cysteine/transforming growth factor-beta binding protein-like (TB) domains. Mutations in the fibrillin-1 gene give rise to Marfan syndrome, a connective tissue disorder with clinical complications in the cardiovascular, skeletal, ocular and other organ systems. Here, we review the consequences of engineered Marfan syndrome mutations in fibrillin-1 at the protein, cellular and organismal levels. Representative point mutations associated with Marfan syndrome in affected individuals have been introduced and analyzed in recombinant fibrillin-1 fragments. Those mutations affect fibrillin-1 on a structural and functional level. Mutations which impair folding of cbEGF domains can affect protein trafficking. Protein folding disrupted by some mutations can lead to defective secretion in mutant fibrillin-1 fragments, whereas fragments with other Marfan mutations are secreted normally. Many Marfan mutations render fibrillin-1 more susceptible to proteolysis. There is also evidence that some mutations affect heparin binding. Few mutations have been further analyzed in mouse models. An extensively studied mouse model of Marfan syndrome expresses mouse fibrillin-1 with a missense mutation (p.C1039G). The mice display similar characteristics to human patients with Marfan syndrome. Overall, the analyses of engineered mutations leading to Marfan syndrome provide important insights into the pathogenic molecular mechanisms exerted by mutated fibrillin-1. Copyright © 2015 Elsevier B.V. All rights reserved.

Epidermal growth factor receptor signaling promotes metastatic prostate cancer through microRNA-96-mediated downregulation of the tumor suppressor ETV6.

Science.gov (United States)

Tsai, Yuan-Chin; Chen, Wei-Yu; Siu, Man Kit; Tsai, Hong-Yuan; Yin, Juan Juan; Huang, Jiaoti; Liu, Yen-Nien

2017-01-01

It has been suggested that ETV6 serves as a tumor suppressor; however, its molecular regulation and cellular functions remain unclear. We used prostate cancer as a model system and demonstrated a molecular mechanism in which ETV6 can be regulated by epidermal growth factor receptor (EGFR) signaling through microRNA-96 (miR-96)-mediated downregulation. In addition, EGFR acts as a transcriptional coactivator that binds to the promoter of primary miR-96 and transcriptionally regulates miR-96 levels. We analyzed two sets of clinical prostate cancer samples, confirmed association patterns that were consistent with the EGFR-miR-96-ETV6 signaling model and demonstrated that the reduced ETV6 levels were associated with malignant prostate cancer. Based on results derived from multiple approaches, we identified the biological functions of ETV6 as a tumor suppressor that inhibits proliferation and metastasis in prostate cancer. We present a molecular mechanism in which EGFR activation leads to the induction of miR-96 expression and suppression of ETV6, which contributes to prostate cancer progression. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Mutation analysis of the CHK2 gene in breast carcinoma and other cancers

International Nuclear Information System (INIS)

Ingvarsson, Sigurdur; Sigbjornsdottir, Bjarnveig I; Huiping, Chen; Hafsteinsdottir, Sigridur H; Ragnarsson, Gisli; Barkardottir, Rosa B; Arason, Adalgeir; Egilsson, Valgardur; Bergthorsson, Jon TH

2002-01-01

Mutations in the CHK2 gene at chromosome 22q12.1 have been reported in families with Li-Fraumeni syndrome. Chk2 is an effector kinase that is activated in response to DNA damage and is involved in cell-cycle pathways and p53 pathways. We screened 139 breast tumors for loss of heterozygosity at chromosome 22q, using seven microsatellite markers, and screened 119 breast tumors with single-strand conformation polymorphism and DNA sequencing for mutations in the CHK2 gene. Seventy-four of 139 sporadic breast tumors (53%) show loss of heterozygosity with at least one marker. These samples and 45 tumors from individuals carrying the BRCA2 999del5 mutation were screened for mutations in the CHK2 gene. In addition to putative polymorphic regions in short mononucleotide repeats in a non-coding exon and intron 2, a germ line variant (T59K) in the first coding exon was detected. On screening 1172 cancer patients for the T59K sequence variant, it was detected in a total of four breast-cancer patients, two colon-cancer patients, one stomach-cancer patient and one ovary-cancer patient, but not in 452 healthy individuals. A tumor-specific 5' splice site mutation at site +3 in intron 8 (TTgt [a → c]atg) was also detected. We conclude that somatic CHK2 mutations are rare in breast cancer, but our results suggest a tumor suppressor function for CHK2 in a small proportion of breast tumors. Furthermore, our results suggest that the T59K CHK2 sequence variant is a low-penetrance allele with respect to tumor growth

Hyperinsulinaemic hypoglycaemia and diabetes mellitus due to dominant ABCC8/KCNJ11 mutations.

LENUS (Irish Health Repository)

Kapoor, R R

2011-10-01

Dominantly acting loss-of-function mutations in the ABCC8\\/KCNJ11 genes can cause mild medically responsive hyperinsulinaemic hypoglycaemia (HH). As controversy exists over whether these mutations predispose to diabetes in adulthood we investigated the prevalence of diabetes in families with dominantly inherited ATP-sensitive potassium (K(ATP)) channel mutations causing HH in the proband.

Hierarchical mutational events compensate for glutamate auxotrophy of a Bacillus subtilis gltC mutant.

Science.gov (United States)

Dormeyer, Miriam; Lübke, Anastasia L; Müller, Peter; Lentes, Sabine; Reuß, Daniel R; Thürmer, Andrea; Stülke, Jörg; Daniel, Rolf; Brantl, Sabine; Commichau, Fabian M

2017-06-01

Glutamate is the major donor of nitrogen for anabolic reactions. The Gram-positive soil bacterium Bacillus subtilis either utilizes exogenously provided glutamate or synthesizes it using the gltAB-encoded glutamate synthase (GOGAT). In the absence of glutamate, the transcription factor GltC activates expression of the GOGAT genes for glutamate production. Consequently, a gltC mutant strain is auxotrophic for glutamate. Using a genetic selection and screening system, we could isolate and differentiate between gltC suppressor mutants in one step. All mutants had acquired the ability to synthesize glutamate, independent of GltC. We identified (i) gain-of-function mutations in the gltR gene, encoding the transcription factor GltR, (ii) mutations in the promoter of the gltAB operon and (iii) massive amplification of the genomic locus containing the gltAB operon. The mutants belonging to the first two classes constitutively expressed the gltAB genes and produced sufficient glutamate for growth. By contrast, mutants that belong to the third class appeared most frequently and solved glutamate limitation by increasing the copy number of the poorly expressed gltAB genes. Thus, glutamate auxotrophy of a B. subtilis gltC mutant can be relieved in multiple ways. Moreover, recombination-dependent amplification of the gltAB genes is the predominant mutational event indicating a hierarchy of mutations. © 2017 Society for Applied Microbiology and John Wiley & Sons Ltd.

FBXW7 mutations in patients with advanced cancers: clinical and molecular characteristics and outcomes with mTOR inhibitors.

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Denis L Jardim

Full Text Available FBXW7 is a tumor suppressor gene responsible for the degradation of several proto-oncogenes. Preclinical data suggest that FBXW7 mutations sensitize cells to mTOR inhibitors. Clinicopathologic characteristics of cancer patients with FBXW7 mutations and their responses to mTOR inhibitors remain unknown.Using multiplex gene panels we evaluated how the FBXW7 mutation affected the cancer phenotype of patients referred to a phase I clinic starting January 2012. Whenever possible patients positive for FBXW7 mutation were treated with regimens containing an mTOR inhibitors and their outcomes were reviewed.FBXW7 mutations were detected in 17 of 418 patients (4.0%. Among tumor types with more than 10 patients tested, FBXW7 mutations occurred in colorectal cancer (7/49; 14.3%, squamous cell cancer of head and neck (2/18; 11.1%, liver (1/13; 7.7%, and ovarian cancers (1/40; 2.5%. No one clinical, pathological or demographic feature was characteristic of the FBXW7-mutated patient population. The mutation occurred in isolation in only 2/17 (12% patients, and KRAS was frequently found as a concomitant mutation, especially in patients with colorectal cancer (6/7; 86%. Ten patients were treated on a protocol containing an mTOR inhibitor, with a median time to treatment failure of 2.8 months (range, 1.3-6.8. One patient with liver cancer (fibrolamellar subtype continues to have a prolonged stable disease for 6.8+ months.In patients with advanced cancers, somatic mutations in FBXW7 usually occur with other simultaneous molecular aberrations, which can contribute to limited therapeutic efficacy of mTOR inhibitors.

The molecular anatomy of spontaneous germline mutations in human testes.

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Jian Qin

2007-09-01

Full Text Available The frequency of the most common sporadic Apert syndrome mutation (C755G in the human fibroblast growth factor receptor 2 gene (FGFR2 is 100-1,000 times higher than expected from average nucleotide substitution rates based on evolutionary studies and the incidence of human genetic diseases. To determine if this increased frequency was due to the nucleotide site having the properties of a mutation hot spot, or some other explanation, we developed a new experimental approach. We examined the spatial distribution of the frequency of the C755G mutation in the germline by dividing four testes from two normal individuals each into several hundred pieces, and, using a highly sensitive PCR assay, we measured the mutation frequency of each piece. We discovered that each testis was characterized by rare foci with mutation frequencies 10(3 to >10(4 times higher than the rest of the testis regions. Using a model based on what is known about human germline development forced us to reject (p < 10(-6 the idea that the C755G mutation arises more frequently because this nucleotide simply has a higher than average mutation rate (hot spot model. This is true regardless of whether mutation is dependent or independent of cell division. An alternate model was examined where positive selection acts on adult self-renewing Ap spermatogonial cells (SrAp carrying this mutation such that, instead of only replacing themselves, they occasionally produce two SrAp cells. This model could not be rejected given our observed data. Unlike the disease site, similar analysis of C-to-G mutations at a control nucleotide site in one testis pair failed to find any foci with high mutation frequencies. The rejection of the hot spot model and lack of rejection of a selection model for the C755G mutation, along with other data, provides strong support for the proposal that positive selection in the testis can act to increase the frequency of premeiotic germ cells carrying a mutation

Combined exposure to X-irradiation followed by N-ethyl-N-nitrosourea treatment alters the frequency and spectrum of Ikaros point mutations in murine T-cell lymphoma

Energy Technology Data Exchange (ETDEWEB)

Kakinuma, Shizuko, E-mail: skakinum@nirs.go.jp [Radiobiology for Children' s Health Research Program, Research Center for Radiation Protection, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555 (Japan); Nishimura, Mayumi; Amasaki, Yoshiko; Takada, Mayumi; Yamauchi, Kazumi; Sudo, Satomi; Shang, Yi [Radiobiology for Children' s Health Research Program, Research Center for Radiation Protection, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555 (Japan); Doi, Kazutaka; Yoshinaga, Shinji [Regulatory Sciences Research Program, Research Center for Radiation Protection, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555 (Japan); Shimada, Yoshiya [Radiobiology for Children' s Health Research Program, Research Center for Radiation Protection, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555 (Japan)

2012-09-01

Ionizing radiation is a well-known carcinogen, but its potency may be influenced by other environmental carcinogens, which is of practical importance in the assessment of risk. Data are scarce, however, on the combined effect of radiation with other environmental carcinogens and the underlying mechanisms involved. We studied the mode and mechanism of the carcinogenic effect of radiation in combination with N-ethyl-N-nitrosourea (ENU) using doses approximately equal to the corresponding thresholds. B6C3F1 mice exposed to fractionated X-irradiation (Kaplan's method) followed by ENU developed T-cell lymphomas in a dose-dependent manner. Radiation doses above an apparent threshold acted synergistically with ENU to promote lymphoma development, whereas radiation doses below that threshold antagonized lymphoma development. Ikaros, which regulates the commitment and differentiation of lymphoid lineage cells, is a critical tumor suppressor gene frequently altered in both human and mouse lymphomas and shows distinct mutation spectra between X-ray- and ENU-induced lymphomas. In the synergistically induced lymphomas, we observed a low frequency of LOH and an inordinate increase of Ikaros base substitutions characteristic of ENU-indcued point mutations, G:C to A:T at non-CpG, A:T to G:C, G:C to T:A and A:T to T:A. This suggests that radiation doses above an apparent threshold activate the ENU mutagenic pathway. This is the first report on the carcinogenic mechanism elicited by combined exposure to carcinogens below and above threshold doses based on the mutation spectrum of the causative gene. These findings constitute a basis for assessing human cancer risk following exposure to multiple carcinogens.

Alternative Splicing and Tissue-specific Elastin Misassembly Act as Biological Modifiers of Human Elastin Gene Frameshift Mutations Associated with Dominant Cutis Laxa*

Science.gov (United States)

Sugitani, Hideki; Hirano, Eiichi; Knutsen, Russell H.; Shifren, Adrian; Wagenseil, Jessica E.; Ciliberto, Christopher; Kozel, Beth A.; Urban, Zsolt; Davis, Elaine C.; Broekelmann, Thomas J.; Mecham, Robert P.

2012-01-01

Elastin is the extracellular matrix protein in vertebrates that provides elastic recoil to blood vessels, the lung, and skin. Because the elastin gene has undergone significant changes in the primate lineage, modeling elastin diseases in non-human animals can be problematic. To investigate the pathophysiology underlying a class of elastin gene mutations leading to autosomal dominant cutis laxa, we engineered a cutis laxa mutation (single base deletion) into the human elastin gene contained in a bacterial artificial chromosome. When expressed as a transgene in mice, mutant elastin was incorporated into elastic fibers in the skin and lung with adverse effects on tissue function. In contrast, only low levels of mutant protein incorporated into aortic elastin, which explains why the vasculature is relatively unaffected in this disease. RNA stability studies found that alternative exon splicing acts as a modifier of disease severity by influencing the spectrum of mutant transcripts that survive nonsense-mediated decay. Our results confirm the critical role of the C-terminal region of tropoelastin in elastic fiber assembly and suggest tissue-specific differences in the elastin assembly pathway. PMID:22573328

Transonic Performance Characteristics of Several Jet Noise Suppressors

Science.gov (United States)

Schmeer, James W.; Salters, Leland B., Jr.; Cassetti, Marlowe D.

1960-01-01

An investigation of the transonic performance characteristics of several noise-suppressor configurations has been conducted in the Langley 16-foot transonic tunnel. The models were tested statically and over a Mach number range from 0.70 to 1.05 at an angle of attack of 0 deg. The primary jet total-pressure ratio was varied from 1.0 (jet off) to about 4.5. The effect of secondary air flow on the performance of two of the configurations was investigated. A hydrogen peroxide turbojet-engine simulator was used to supply the hot-jet exhaust. An 8-lobe afterbody with centerbody, short shroud, and secondary air had the highest thrust-minus-drag coefficients of the six noise-suppressor configurations tested. The 12-tube and 12-lobe afterbodies had the lowest internal losses. The presence of an ejector shroud partially shields the external pressure distribution of the 8-lobe after-body from the influence of the primary jet. A ring-airfoil shroud increased the static thrust of the annular nozzle but generally decreased the thrust minus drag at transonic Mach numbers.

UV mutagenesis in E. coli with excision repair initiated by uvrABC or denV gene products

Energy Technology Data Exchange (ETDEWEB)

Bockrath, R; Hodes, M Z; Mosbaugh, P; Valerie, K; de Riel, J K

1988-03-01

Mutation frequency responses produced by ultraviolet light are compared in 4 closely related strains of E.coli B/r having the same tyr(Oc) allele and different excision-repair capabilities. The production of Tyr/sup +/ prototrophic mutants is classified into back-mutations and de novo or converted glutamine tRNA suppressor mutations to indicate different mutation events. Cells transformed with the plasmid pdenV-7 require larger exposures than the parent strains to produce comparable mutation frequency responses, indicating that DenV activity can repair mutatagenic photoproducts. When damage reduction by UvrABC or DenV is compared for each of the specific categories of mutation, the results are consistent with the idea that pyrimidine dimers infrequently or never target back-mutations of this allele, frequently target the de novo suppressor mutations, and extensively or exclusively target the converted suppressor mutations. This analysis is based on the distinction that UvrABC-initiated excision repair recognizes dimer and non-dimer photoproducts but that DenV-initiated repair recognizes only pyrimidine dimers. 44 refs.; 3 figs.; 2 tabs.

Concanavalin A-induced and spontaneous suppressor cell activities in peripheral blood lymphocytes and spleen cells from gastric cancer patients.

Science.gov (United States)

Toge, T; Hamamoto, S; Itagaki, E; Yajima, K; Tanada, M; Nakane, H; Kohno, H; Nakanishi, K; Hattori, T

1983-11-01

In 173 gastric cancer patients, activities of Concanavalin-A-induced suppressor cells (Con-AS) and spontaneous suppressor cells (SpS) in peripheral blood lymphocytes (PBL), splenic vein lymphocytes (SVL), and spleen cells (SCs) were investigated. Suppressions by Con-AS in PBL were significantly effective in patients of Stages III and IV, while suppressions by SpS were effective in patients with recurrent tumors. Thus, in PBLs of cancer patients, suppressor precursors, which are considered to be activated in vitro by Concanavalin-A, seemed to appear with the advances of the disease, and SpS activities, which could be already activated in vivo, seemed to increase in the terminal stage. In SCs, increased activities of Con-AS, but normal activities of SpS, were observed, and these suppressor-cell populations consisted of glass nonadherent cells. Suppressor activities of SCs would be due to suppressor T-cells, not to other types of cells. Furthermore, Con-AS existed in the medium-sized lymphocytes, which were fractionated on the basis of cell size, while SpS in the large-sized lymphocytes. A higher proportion of T-cells, bearing Fc receptors for IgG, was observed in the larger-sized lymphocyte fractions. Cell numbers in the large-sized lymphocyte fraction tended to increase with the advances of tumors. From these results, it is suggested that higher presence of suppressor precursors and the increase of SpS activities may occur in cancer patients, depending on the tumor advancing.

Relationship among tobacco habits, human papilloma virus (HPV) infection, p53 polymorphism/mutation and the risk of oral squamous cell carcinoma

OpenAIRE

Bidyut Chakrobarty; Jay Gopal Roy; Sumit Majumdar; Divya Uppala

2014-01-01

The prevalence of oral squamous cell carcinoma (OSCC) has significantly increased over decades in several countries and human papilloma virus (HPV) has been indicated as one of the underlying causes. This suggests that HPV plays a role in the early stages of carcinogenesis but is not a requisite for the maintenance and progression of malignant state. p53 is a tumor suppressor gene that checks the cell and promotes apoptosis and cell repair that can be deactivated by mutations and a viral inte...

Three genes for mitochondrial proteins suppress null-mutations in both Afg3 and Rca1 when over-expressed.

Science.gov (United States)

Rep, M; Nooy, J; Guélin, E; Grivell, L A

1996-08-01

The AFG3 gene of Saccharomyces cerevisiae encodes a mitochondrial inner membrane protein with ATP-dependent protease activity. To gain more insight into the function of this protein, multi-copy suppressors of an afg3-null mutation were isolated. Three genes were found that restored partial growth on non-fermentable carbon sources, all of which affect the biogenesis of respiratory competent mitochondria: PIM1(LON) encodes a matrix-localized ATP-dependent protease involved in the turnover of matrix proteins; OXA1(PET1402) encodes a putative mitochondrial inner membrane protein involved in the biogenesis of the respiratory chain; and MBA1 encodes a mitochondrial protein required for optimal respiratory growth. All three genes also suppressed a null mutation in a related gene, RCA1, as well as in the combination of afg3- and rca1-null.

CP-31398 inhibits the growth of p53-mutated liver cancer cells in vitro and in vivo.

Science.gov (United States)

He, Xing-Xing; Zhang, Yu-Nan; Yan, Jun-Wei; Yan, Jing-Jun; Wu, Qian; Song, Yu-Hu

2016-01-01

The tumor suppressor p53 is one of the most frequently mutated genes in hepatocellular carcinoma (HCC). Previous studies demonstrated that CP-31398 restored the native conformation of mutant p53 and trans-activated p53 downstream genes in tumor cells. However, the research on the application of CP-31398 to liver cancer has not been reported. Here, we investigated the effects of CP-31398 on the phenotype of HCC cells carrying p53 mutation. The effects of CP-31398 on the characteristic of p53-mutated HCC cells were evaluated through analyzing cell cycle, cell apoptosis, cell proliferation, and the expression of p53 downstream genes. In tumor xenografts developed by PLC/PRF/5 cells, the inhibition of tumor growth by CP-31398 was analyzed through gross morphology, growth curve, and the expression of p53-related genes. Firstly, we demonstrated that CP-31398 inhibited the growth of p53-mutated liver cancer cells in a dose-dependent and p53-dependent manner. Then, further study showed that CP-31398 re-activated wild-type p53 function in p53-mutated HCC cells, which resulted in inhibitive response of cell proliferation and an induction of cell-cycle arrest and apoptosis. Finally, in vivo data confirmed that CP-31398 blocked the growth of xenografts tumors through transactivation of p53-responsive downstream molecules. Our results demonstrated that CP-31398 induced desired phenotypic change of p53-mutated HCC cells in vitro and in vivo, which revealed that CP-31398 would be developed as a therapeutic candidate for HCC carrying p53 mutation.

Characteristics of DTH suppressor cells in mice infected with Candida albicans.

Science.gov (United States)

Valdez, J C; Mesón, O E; Sirena, A; de Alderete, N G

1987-05-01

Inoculation of 10(8) C. albicans intraperitoneally into Balb/c mice at given dosage was reported to induce suppression of antigen-specific delayed-type hypersensitivity. Adoptive transfer of spleen cells into normal syngeneic mice pre-treated with Cyclophosphamide confirmed the existence of suppressor cells in mice. Such cells were sensitive to treatment with anti-theta serum and complement, non-adherent to Sephadex G-10. A pretreatment of the mice with Cyclophosphamide eliminated DTH suppression. Treatment with antimacrophage agents via intraperitoneal abrogated suppression only if being effected before inoculation of alive 10(8) Candida albicans. It is concluded that the spleen suppressor cell is a T-lymphocyte whose precursor is Cyclophosphamide-sensitive, requiring the macrophage to be induced.

Non-cell autonomous or secretory tumor suppression.

Science.gov (United States)

Chua, Christelle En Lin; Chan, Shu Ning; Tang, Bor Luen

2014-10-01

Many malignancies result from deletions or loss-of-function mutations in one or more tumor suppressor genes, the products of which curb unrestrained growth or induce cell death in those with dysregulated proliferative capacities. Most tumor suppressors act in a cell autonomous manner, and only very few proteins are shown to exert a non-cell autonomous tumor suppressor function on other cells. Examples of these include members of the secreted frizzled-related protein (SFRP) family and the secreted protein acidic and rich in cysteine (SPARC)-related proteins. Very recent findings have, however, considerably expanded our appreciation of non-cell autonomous tumor suppressor functions. Broadly, this may occur in two ways. Intracellular tumor suppressor proteins within cells could in principle inhibit aberrant growth of neighboring cells by conditioning an antitumor microenvironment through secreted factors. This is demonstrated by an apparent non-cell autonomous tumor suppressing property of p53. On the other hand, a tumor suppressor produced by a cell may be secreted extracellularly, and taken up by another cell with its activity intact. Intriguingly, this has been recently shown to occur for the phosphatase and tensin homolog (PTEN) by both conventional and unconventional modes of secretion. These recent findings would aid the development of therapeutic strategies that seek to reinstate tumor suppression activity in therapeutically recalcitrant tumor cells, which have lost it in the first place. © 2014 Wiley Periodicals, Inc.

Effect of duct shape, Mach number, and lining construction on measured suppressor attenuation and comparison with theory

Science.gov (United States)

Olsen, W. A.; Krejsa, E. A.; Coats, J. W.

1972-01-01

Noise attenuation was measured for several types of cylindrical suppressors that use a duct lining composed of honeycomb cells covered with a perforated plate. The experimental technique used gave attenuation data that were repeatable and free of noise floors and other sources of error. The suppressor length, the effective acoustic diameter, suppressor shape and flow velocity were varied. The agreement among the attenuation data and two widely used analytical models was generally satisfactory. Changes were also made in the construction of the acoustic lining to measure their effect on attenuation. One of these produced a very broadband muffler.

Mutations in Cancer Cause Gain of Cysteine, Histidine, and Tryptophan at the Expense of a Net Loss of Arginine on the Proteome Level

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Viktoriia Tsuber

2017-07-01

Full Text Available Accumulation of somatic mutations is critical for the transition of a normal cell to become cancerous. Mutations cause amino acid substitutions that change properties of proteins. However, it has not been studied as to what extent the composition and accordingly chemical properties of the cell proteome is altered as a result of the increased mutation load in cancer. Here, we analyzed data on amino acid substitutions caused by mutations in about 2000 protein coding genes from the Cancer Cell Line Encyclopedia that contains information on nucleotide and amino acid alterations in 782 cancer cell lines, and validated the analysis with information on amino acid substitutions for the same set of proteins in the Catalogue of Somatic Mutations in Cancer (COSMIC; v78 in circa 18,000 tumor samples. We found that nonsynonymous single nucleotide substitutions in the analyzed proteome subset ultimately result in a net gain of cysteine, histidine, and tryptophan at the expense of a net loss of arginine. The extraordinary loss of arginine may be attributed to some extent to composition of its codons as well as to the importance of arginine in the functioning of prominent tumor suppressor proteins like p53.

Mutational profile of GNAQQ209 in human tumors.

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Simona Lamba

Full Text Available BACKGROUND: Frequent somatic mutations have recently been identified in the ras-like domain of the heterotrimeric G protein alpha-subunit (GNAQ in blue naevi 83%, malignant blue naevi (50% and ocular melanoma of the uvea (46%. The mutations exclusively affect codon 209 and result in GNAQ constitutive activation which, in turn, acts as a dominant oncogene. METHODOLOGY: To assess if the mutations are present in other tumor types we performed a systematic mutational profile of the GNAQ exon 5 in a panel of 922 neoplasms, including glioblastoma, gastrointestinal stromal tumors (GIST, acute myeloid leukemia (AML, blue naevi, skin melanoma, bladder, breast, colorectal, lung, ovarian, pancreas, and thyroid carcinomas. PRINCIPAL FINDINGS: We detected the previously reported mutations in 6/13 (46% blue naevi. Changes affecting Q209 were not found in any of the other tumors. Our data indicate that the occurrence of GNAQ mutations display a unique pattern being present in a subset of melanocytic tumors but not in malignancies of glial, epithelial and stromal origin analyzed in this study.

Demonstration of helicase activity in the nonstructural protein, NSs, of the negative-sense RNA virus, groundnut bud necrosis virus.

Science.gov (United States)

Bhushan, Lokesh; Abraham, Ambily; Choudhury, Nirupam Roy; Rana, Vipin Singh; Mukherjee, Sunil Kumar; Savithri, Handanahal Subbarao

2015-04-01

The nonstructural protein NSs, encoded by the S RNA of groundnut bud necrosis virus (GBNV) (genus Tospovirus, family Bunyaviridae) has earlier been shown to possess nucleic-acid-stimulated NTPase and 5' α phosphatase activity. ATP hydrolysis is an essential function of a true helicase. Therefore, NSs was tested for DNA helicase activity. The results demonstrated that GBNV NSs possesses bidirectional DNA helicase activity. An alanine mutation in the Walker A motif (K189A rNSs) decreased DNA helicase activity substantially, whereas a mutation in the Walker B motif resulted in a marginal decrease in this activity. The parallel loss of the helicase and ATPase activity in the K189A mutant confirms that NSs acts as a non-canonical DNA helicase. Furthermore, both the wild-type and K189A NSs could function as RNA silencing suppressors, demonstrating that the suppressor activity of NSs is independent of its helicase or ATPase activity. This is the first report of a true helicase from a negative-sense RNA virus.

Repressive mutations restore function-loss caused by the disruption of trimerization in Escherichia coli multidrug transporter AcrB

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Zhaoshuai eWang

2015-01-01

Full Text Available AcrAB-TolC and their homologs are major multidrug efflux systems in Gram-negative bacteria. The inner membrane component AcrB functions as a trimer. Replacement of Pro223 by Gly in AcrB decreases the trimer stability and drastically reduces the drug efflux activity. The goal of this study is to identify suppressor mutations that restore function to mutant AcrBP223G and explore the mechanism of function recovery. Two methods were used to introduce random mutations into the plasmid of AcrBP223G. Mutants with elevated drug efflux activity were identified, purified, and characterized to examine their expression level, trimer stability, interaction with AcrA, and substrate binding. Nine single-site repressor mutations were identified, including T199M, D256N, A209V, G257V, M662I, Q737L, D788K, P800S, and E810K. Except for M662I, all other mutations located in the docking region of the periplasmic domain. While three mutations, T199M, A209V, and D256N, significantly increased the trimer stability, none of them restored the trimer affinity to the wild type level. M662, the only site of mutation that located in the porter domain, was involved in substrate binding. Our results suggest that the function loss resulted from compromised AcrB trimerization could be restored through various mechanisms involving the compensation of trimer stability and substrate binding.

Improved crystallization and diffraction of caffeine-induced death suppressor protein 1 (Cid1)

Energy Technology Data Exchange (ETDEWEB)

Yates, Luke A., E-mail: luke@strubi.ox.ac.uk; Durrant, Benjamin P.; Barber, Michael; Harlos, Karl [University of Oxford, Roosevelt Drive, Oxford OX3 7BN (United Kingdom); Fleurdépine, Sophie; Norbury, Chris J. [University of Oxford, South Parks Road, Oxford OX1 3RE (United Kingdom); Gilbert, Robert J. C., E-mail: luke@strubi.ox.ac.uk [University of Oxford, Roosevelt Drive, Oxford OX3 7BN (United Kingdom)

2015-02-21

The use of truncation and RNA-binding mutations of caffeine induced death suppressor protein 1 (Cid1) as a means to enhance crystallogenesis leading to an improvement of X-ray diffraction resolution by 1.5 Å is reported. The post-transcriptional addition of uridines to the 3′-end of RNAs is an important regulatory process that is critical for coding and noncoding RNA stability. In fission yeast and metazoans this untemplated 3′-uridylylation is catalysed by a single family of terminal uridylyltransferases (TUTs) whose members are adapted to specific RNA targets. In Schizosaccharomyces pombe the TUT Cid1 is responsible for the uridylylation of polyadenylated mRNAs, targeting them for destruction. In metazoans, the Cid1 orthologues ZCCHC6 and ZCCHC11 uridylate histone mRNAs, targeting them for degradation, but also uridylate microRNAs, altering their maturation. Cid1 has been studied as a model TUT that has provided insights into the larger and more complex metazoan enzyme system. In this paper, two strategies are described that led to improvements both in the crystallogenesis of Cid1 and in the resolution of diffraction by ∼1.5 Å. These advances have allowed high-resolution crystallo@@graphic studies of this TUT system to be initiated.

Improved crystallization and diffraction of caffeine-induced death suppressor protein 1 (Cid1)

International Nuclear Information System (INIS)

Yates, Luke A.; Durrant, Benjamin P.; Barber, Michael; Harlos, Karl; Fleurdépine, Sophie; Norbury, Chris J.; Gilbert, Robert J. C.

2015-01-01

The use of truncation and RNA-binding mutations of caffeine induced death suppressor protein 1 (Cid1) as a means to enhance crystallogenesis leading to an improvement of X-ray diffraction resolution by 1.5 Å is reported. The post-transcriptional addition of uridines to the 3′-end of RNAs is an important regulatory process that is critical for coding and noncoding RNA stability. In fission yeast and metazoans this untemplated 3′-uridylylation is catalysed by a single family of terminal uridylyltransferases (TUTs) whose members are adapted to specific RNA targets. In Schizosaccharomyces pombe the TUT Cid1 is responsible for the uridylylation of polyadenylated mRNAs, targeting them for destruction. In metazoans, the Cid1 orthologues ZCCHC6 and ZCCHC11 uridylate histone mRNAs, targeting them for degradation, but also uridylate microRNAs, altering their maturation. Cid1 has been studied as a model TUT that has provided insights into the larger and more complex metazoan enzyme system. In this paper, two strategies are described that led to improvements both in the crystallogenesis of Cid1 and in the resolution of diffraction by ∼1.5 Å. These advances have allowed high-resolution crystallo@@graphic studies of this TUT system to be initiated

Relationship among tobacco habits, human papilloma virus (HPV) infection, p53 polymorphism/mutation and the risk of oral squamous cell carcinoma.

Science.gov (United States)

Chakrobarty, Bidyut; Roy, Jay Gopal; Majumdar, Sumit; Uppala, Divya

2014-05-01

The prevalence of oral squamous cell carcinoma (OSCC) has significantly increased over decades in several countries and human papilloma virus (HPV) has been indicated as one of the underlying causes. This suggests that HPV plays a role in the early stages of carcinogenesis but is not a requisite for the maintenance and progression of malignant state. p53 is a tumor suppressor gene that checks the cell and promotes apoptosis and cell repair that can be deactivated by mutations and a viral interaction leading to cancer and individuals with particular polymorphic variant of p53 is more susceptible to HPV-induced carcinogenesis. The present study has been carried out to detect and correlate p53 polymorphism/mutation, HPV DNA in the biopsy samples of oral cancer patients who had tobacco habits.

Alloantigen-specific suppressor T cells are not inhibited by cyclosporin A, but do require IL 2 for activation

International Nuclear Information System (INIS)

Bucy, R.P.

1986-01-01

Alloantigen-specific suppressor T cells are activated from normal murine spleen cells in mixed lymphocyte reactions (MLR). These T cells are radioresistant and suppress the activation of cytotoxic T lymphocytes (CTL) in second primary MLR cultures. This report demonstrates that cyclosporin A (CsA) blocks the activation of these suppressor cells at a dose of 1 microgram/ml. However, reconstitution of CsA blocked cultures with IL 2 restores the activation of the suppressor T cells, but fails to significantly restore the activation of CTL in these same cultures. This differential activation requirement was used to establish T cell lines that demonstrate enriched suppressor cell activity but depletion of CTL activity. These findings are discussed in terms of the mechanism of action of CsA in these distinct T cell subsets and the relevance to models of allograft unresponsiveness

Clonal expansion to anaplasia in Wilms` tumors is associated with p53 mutations

Energy Technology Data Exchange (ETDEWEB)

Pelletier, J.; Beckwith, B.; Bardeesy, N. [Loma Linda Univ., CA (United States)]|[McGill Univ., Montreal (Canada)

1994-09-01

The genetics of Wilms` tumor (WT), a pediatric malignancy of the kidney, is complex. Three loci are implicated in WT initiation and include the WT1 tumor suppressor gene (residing at 11p13), an 11p15 locus, and a non-11p locus. As well, allelic loss at 16q24 in {approximately}20% of sporadic WTs suggests the location of (an) additional gene(s) involved in tumor progression. Initiation and progression in WTs is associated with multiple histological variants. Anaplasia is a rare WT subtype associated with poor prognosis and defined by enlarged and multipolar mitotic figures, a threefold nuclear enlargement (compared with adjacent nuclei of the same cell type), and hyperchromasia of the enlarged nuclei. We have previously demonstrated that p53 gene mutations are exclusively associated with anaplastic WTs, being absent from a large number of non-anaplastic WTs analyzed. To determine if such mutations are involved in clonal progression to anaplasia, we performed a retrospective analysis of histologically defined sections from tumor specimens. Six of ten WTs demonstrated p53 mutations by PCR-single stranded conformational polymorphism analysis. Two of these samples were paired, consisting of geographically demarcated anaplastic cells embedded within a non-anaplastic tumor bed. In these cases, p53 mutations were only present in the anaplastic region of the tumor. An overall decrease in the number of apoptotic cells was found associated with the anaplastic tumor region, compared to adjacent non-anaplastic tumor bed. These results indicate that p53 mutations arise during progression to anaplasia late in Wilms` tumor etiology and are associated with a more aggressive form of this cancer.

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

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.

Myeloid-derived suppressor activity is mediated by monocytic lineages maintained by continuous inhibition of extrinsic and intrinsic death pathways.

Science.gov (United States)

Haverkamp, Jessica M; Smith, Amber M; Weinlich, Ricardo; Dillon, Christopher P; Qualls, Joseph E; Neale, Geoffrey; Koss, Brian; Kim, Young; Bronte, Vincenzo; Herold, Marco J; Green, Douglas R; Opferman, Joseph T; Murray, Peter J

2014-12-18

Nonresolving inflammation expands a heterogeneous population of myeloid suppressor cells capable of inhibiting T cell function. This heterogeneity has confounded the functional dissection of individual myeloid subpopulations and presents an obstacle for antitumor immunity and immunotherapy. Using genetic manipulation of cell death pathways, we found the monocytic suppressor-cell subset, but not the granulocytic subset, requires continuous c-FLIP expression to prevent caspase-8-dependent, RIPK3-independent cell death. Development of the granulocyte subset requires MCL-1-mediated control of the intrinsic mitochondrial death pathway. Monocytic suppressors tolerate the absence of MCL-1 provided cytokines increase expression of the MCL-1-related protein A1. Monocytic suppressors mediate T cell suppression, whereas their granulocytic counterparts lack suppressive function. The loss of the granulocytic subset via conditional MCL-1 deletion did not alter tumor incidence implicating the monocytic compartment as the functionally immunosuppressive subset in vivo. Thus, death pathway modulation defines the development, survival, and function of myeloid suppressor cells. Copyright © 2014 Elsevier Inc. All rights reserved.

The Ras suppressor-1 (RSU-1 in cancer

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Lefteris C Zacharia

2017-04-01

Full Text Available Primary tumors are seldom the cause of death for cancer patients as most patients die from metastatic disease. Thus, deciphering metastatic mechanisms and key molecules involved is of utmost importance for the improved survival of cancer patients. Metastasis is a complex process in which cancer cells dissociate from the original tumor and spread to distant sites of the body. During the metastatic process, cancer cells lose contact both with the extracellular matrix (ECM and the neighboring cells within the primary tumor, thus invading though surrounding tissues. Therefore, ECM, and ECM-related adhesion proteins play a critical role in the metastatic process. Ras suppressor-1 (RSU-1 was first identified as a suppressor of Ras-dependent oncogenic transformation and is localized to cell-ECM adhesions where it is known to interact with the pro-survival adhesion protein PINCH-1. Although the connection to cancer is obvious, little is known regarding its expression in various cancer types. This opinion piece is focusing on recent literature regarding the expression of RSU-1 in various cancer types and the possible molecular mechanism of its action, pointing towards questions that need still to be addressed in this research field.

Mutation induction by and mutational interaction between monochromatic wavelength radiations in the near-ultraviolet and visible ranges

International Nuclear Information System (INIS)

Tyrrell, R.M.

1980-01-01

The induction of mutations (reversion to tryptophan independence) by various UV (254, 313, 334 and 365 nm) and visible (405 and 434 nm) wavelengths was measured in exponential phase populations of Escherichia coli B/r thy trp and B/r thy trp uvr A by assay of irradiated populations on semi-enriched media. No mutations were induced in the repair proficient strain at wavelengths longer than 313 nm. Mutations were induced to the excisionless strain at wavelengths as long as 405 nm but less than expected from the known amount of DNA damage induced. Irradiation at the long wavelenths (434, 405, 365 and 334 nm) suppressed the appearance of 254- or 313 nm-induced mutations in the repair competent strain but not in the excision deficient strain. The relative dose-requirement for mutation suppression was related to the relative efficiency of these wavelengths in inducing growth delay. These results suggest that the growth delay induced by near-UV and visible wavelenghts allows more time for the 'error-free' excision repair process to act on the potentially mutagenic lesions induced by 254- and 313-nm radiations, thereby reducing the mutation frequency observed in the repair-proficient strain. The level of near-UV mutation induced in the excision deficient strain is lower than expected from the DNA damage known to be induced. It is possible that near-UV radiation induces a class of lethal lesions that are not susceptible to error-prone repair. (author)

Genetic susceptibility to cancer

International Nuclear Information System (INIS)

Sasaki, Masao S.

1995-01-01

The normal development and function of tissues are under the regulation of programmed expression of genes involved in the proliferation and differentiation. Tumor development can be identified as the abnormal or deregulated expression of such genes. Two distinct classes of genes have been implicated in cancer development; oncogenes and tumor-suppressor genes. Those genes are potential target for radiation carcinogenesis. However, contemporal view of mutations of oncogenes and tumor-suppressor genes in radiogenic and non-radiogenic human cancers do not match to the spectrum of radiation-induced mutation in the selected genes, and raise the question whether radiations are primarily responsible for the initiation of carcinogenesis by mutation of those genes as primary target. There is now a growing evidence for the radiation to stimulate cell growth, which is followed by suppression. Such stimulatory effects of radiation may evoke the growth-promoting and -suppressing genes, or oncogenes and tumor-suppressor genes. This may lead to a testable proposition that constitutively present gain-of-function mutations in oncogenes and/or loss-of-function mutations in tumor-suppressor genes, accumulated spontaneously or environmentally, may play a significant role in the radiation carcinogenesis. (author)

The Value of Suppressor Effects in Explicating the Construct Validity of Symptom Measures

Science.gov (United States)

Watson, David; Clark, Lee Anna; Chmielewski, Michael; Kotov, Roman

2013-01-01

Suppressor effects are operating when the addition of a predictor increases the predictive power of another variable. We argue that suppressor effects can play a valuable role in explicating the construct validity of symptom measures by bringing into clearer focus opposing elements that are inherent—but largely hidden—in the measure’s overall score. We illustrate this point using theoretically grounded, replicated suppressor effects that have emerged in analyses of the original Inventory of Depression and Anxiety Symptoms (IDAS; Watson et al., 2007) and its expanded second version (IDAS-II; Watson et al., 2012). In Study 1, we demonstrate that the IDAS-II Appetite Gain and Appetite Loss scales contain both (a) a shared distress component that creates a positive correlation between them and (b) a specific symptom component that produces a natural negative association between them (i.e., people who recently have experienced decreased interest in food/loss of appetite are less likely to report a concomitant increase in appetite/weight). In Study 2, we establish that mania scales also contain two distinct elements—namely, high energy/positive emotionality and general distress/dysfunction—that oppose each another in many instances. In both studies, we obtained evidence of suppression effects that were highly robust across different types of respondents (e.g., clinical outpatients, community adults, college students) and using both self-report and interview-based measures. These replicable suppressor effects establish that many homogeneous, unidimensional symptom scales actually contain distinguishable components with distinct—at times, even antagonistic—properties. PMID:23795886

Preimplantation genetic diagnosis of Von Hippel-Lindau disease cancer syndrome by combined mutation and segregation analysis

Directory of Open Access Journals (Sweden)

Denilce R. Sumita

2007-03-01

Full Text Available Von Hippel-Lindau (VHL disease is an autosomal dominant cancer syndrome, associated with the development of tumors and cysts in multiple organ systems, whose expression and age of onset are highly variable. The VHL disease tumor suppressor gene (VHL maps to 3p25-p26 and mutations ranging from a single base change to large deletions have been detected in patients with VHL disease. We developed a single cell PCR protocol for preimplantation genetic diagnosis (PGD of VHL disease to select unaffected embryos on the basis of the detection of the specific mutation and segregation analysis of polymorphic linked markers. Multiplex-nested PCR using single buccal cells of an affected individual were performed in order to test the accuracy and reliability of this single-cell protocol. For each locus tested, amplification efficiency was 83% to 87% and allelic drop-out rates ranged from 12% to 8%. Three VHL disease PGD cycles were performed on cells from a couple with paternal transmission of a 436delC mutation in exon 2 of the VHL gene, leading to the identification of three unaffected embryos. Independent of the mutation present, this general PGD protocol for the diagnosis of VHL disease can be used in families informative for either the D3S1038 or D3S1317 microsatellite markers.

Frequent alteration of MLL3 frameshift mutations in microsatellite deficient colorectal cancer.

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Yoshiyuki Watanabe

Full Text Available MLL3 is a histone 3-lysine 4 methyltransferase with tumor-suppressor properties that belongs to a family of chromatin regulator genes potentially altered in neoplasia. Mutations in MLL3 were found in a whole genome analysis of colorectal cancer but have not been confirmed by a separate study.We analyzed mutations of coding region and promoter methylation in MLL3 using 126 cases of colorectal cancer. We found two isoforms of MLL3 and DNA sequencing revealed frameshift and other mutations affecting both isoforms of MLL3 in colorectal cancer cells and 19 of 134 (14% primary colorectal samples analyzed. Moreover, frameshift mutations were more common in cases with microsatellite instability (31% both in CRC cell lines and primary tumors. The largest isoform of MLL3 is transcribed from a CpG island-associated promoter that has highly homology with a pseudo-gene on chromosome 22 (psiTPTE22. Using an assay which measured both loci simultaneously we found prominent age related methylation in normal colon (from 21% in individuals less than 25 years old to 56% in individuals older than 70, R = 0.88, p<0.001 and frequent hypermethylation (83% in both CRC cell lines and primary tumors. We next studied the two loci separately and found that age and cancer related methylation was solely a property of the pseudogene CpG island and that the MLL3 loci was unmethylated.We found that frameshift mutations of MLL3 in both CRC cells and primary tumor that were more common in cases with microsatellite instability. Moreover, we have shown CpG island-associated promoter of MLL3 gene has no DNA methylation in CRC cells but also primary tumor and normal colon, and this region has a highly homologous of pseudo gene (psiTPTE22 that was age relate DNA methylation.

The Fbw7 tumor suppressor targets KLF5 for ubiquitin-mediated degradation and suppresses breast cell proliferation.

Science.gov (United States)

Zhao, Dong; Zheng, Han-Qiu; Zhou, Zhongmei; Chen, Ceshi

2010-06-01

Fbw7 is a tumor suppressor frequently inactivated in cancers. The KLF5 transcription factor promotes breast cell proliferation and tumorigenesis through upregulating FGF-BP. The KLF5 protein degrades rapidly through the ubiquitin proteasome pathway. Here, we show that the Skp1-CUL1-Fbw7 E3 ubiquitin ligase complex (SCF(Fbw7)) targets KLF5 for ubiquitin-mediated degradation in a GSK3beta-mediated KLF5 phosphorylation-dependent manner. Mutation of the critical S303 residue in the KLF5 Cdc4 phospho-degrons motif ((303)SPPSS) abolishes the protein interaction, ubiquitination, and degradation by Fbw7. Inactivation of endogenous Fbw7 remarkably increases the endogenous KLF5 protein abundances. Endogenous Fbw7 suppresses the FGF-BP gene expression and breast cell proliferation through targeting KLF5 for degradation. These findings suggest that Fbw7 inhibits breast cell proliferation at least partially through targeting KLF5 for proteolysis. This new regulatory mechanism of KLF5 degradation may result in useful diagnostic and therapeutic targets for breast cancer and other cancers. Copyright 2010 AACR.

Study the Molecular Association between a Deletion Mutation in CHEK2 gene (5395 bp and Breast Cancer

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Manijeh Jalilvand

2015-07-01

Full Text Available Background & Objectives: Breast cancer is the most common cancer among women and the second most common cause of cancer death. Genetic factors play an important role in the development of breast cancer. Among these genetic factors, CHEk2 (checkpoint kinase 2 gene, as a tumor suppressor gene, plays a critical role in DNA repair. Germline mutations in CEHK2 result in the loss of this feature. One of the mutations in CHEK2 gene is a 5395 bp deletion mutation which has been associated with the increasing risk of Breast Cancer in some populations in the world.  In the present study, we investigated the association between a 5395 bp deletion mutation in CHEK2 gene and the risk of Breast Cancer in the women of an Iranian population. Methods: Pathologic information of 38 cases under the age of 45 and 62 cases over the age of 45 referring to surgery ward of Milad Hospital in Tehran were extracted. 100 healthy controls were included in the study as well. After obtaining informed consent, 5 mL whole blood was taken DNA was successfully isolated. Multiplex PCR was used to investigate the association between a 5395bp deletion mutation in CHEK2 gene and increasing risk of Breast Cancer among patients. Results: The 5395bp deletion mutation in CHEK2 gene was not found in any of the participating groups of patients or heathy controls. Conclusion: The present study revealed that there is no significant relation between increasing the risk of Breast Cancer and bearing large deletion mutation in exon 9 and exon 10 of CHECK2 gene.

DMPD: Suppressor of cytokine signaling (SOCS) 2, a protein with multiple functions. [Dynamic Macrophage Pathway CSML Database

Lifescience Database Archive (English)

Full Text Available 17070092 Suppressor of cytokine signaling (SOCS) 2, a protein with multiple function...Epub 2006 Oct 27. (.png) (.svg) (.html) (.csml) Show Suppressor of cytokine signaling (SOCS) 2, a protein with multiple function...SOCS) 2, a protein with multiple functions. Authors Rico-Bautista E, Flores-Morales A, Fernandez-Perez L. Pu

Mutation analysis of inhibitory guanine nucleotide binding protein alpha (GNAI) loci in young and familial pituitary adenomas.

Science.gov (United States)

Demir, Hande; Donner, Iikki; Kivipelto, Leena; Kuismin, Outi; Schalin-Jäntti, Camilla; De Menis, Ernesto; Karhu, Auli

2014-01-01

Pituitary adenomas are neoplasms of the anterior pituitary lobe and account for 15-20% of all intracranial tumors. Although most pituitary tumors are benign they can cause severe symptoms related to tumor size as well as hypopituitarism and/or hypersecretion of one or more pituitary hormones. Most pituitary adenomas are sporadic, but it has been estimated that 5% of patients have a familial background. Germline mutations of the tumor suppressor gene aryl hydrocarbon receptor-interacting protein (AIP) predispose to hereditary pituitary neoplasia. Recently, it has been demonstrated that AIP mutations predispose to pituitary tumorigenesis through defective inhibitory GTP binding protein (Gαi) signaling. This finding prompted us to examine whether germline loss-of-function mutations in inhibitory guanine nucleotide (GTP) binding protein alpha (GNAI) loci are involved in genetic predisposition of pituitary tumors. To our knowledge, this is the first time GNAI genes are sequenced in order to examine the occurrence of inactivating germline mutations. Thus far, only somatic gain-of-function hot-spot mutations have been studied in these loci. Here, we have analyzed the coding regions of GNAI1, GNAI2, and GNAI3 in a set of young sporadic somatotropinoma patients (n = 32; mean age of diagnosis 32 years) and familial index cases (n = 14), thus in patients with a disease phenotype similar to that observed in AIP mutation carriers. In addition, expression of Gαi proteins was studied in human growth hormone (GH), prolactin (PRL), adrenocorticotropic hormone (ACTH)-secreting and non-functional pituitary tumors. No pathogenic germline mutations affecting the Gαi proteins were detected. The result suggests that loss-of-function mutations of GNAI loci are rare or nonexistent in familial pituitary adenomas.

ABCE1 is a highly conserved RNA silencing suppressor.

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Kairi Kärblane

Full Text Available ATP-binding cassette sub-family E member 1 (ABCE1 is a highly conserved protein among eukaryotes and archaea. Recent studies have identified ABCE1 as a ribosome-recycling factor important for translation termination in mammalian cells, yeast and also archaea. Here we report another conserved function of ABCE1. We have previously described AtRLI2, the homolog of ABCE1 in the plant Arabidopsis thaliana, as an endogenous suppressor of RNA silencing. In this study we show that this function is conserved: human ABCE1 is able to suppress RNA silencing in Nicotiana benthamiana plants, in mammalian HEK293 cells and in the worm Caenorhabditis elegans. Using co-immunoprecipitation and mass spectrometry, we found a number of potential ABCE1-interacting proteins that might support its function as an endogenous suppressor of RNA interference. The interactor candidates are associated with epigenetic regulation, transcription, RNA processing and mRNA surveillance. In addition, one of the identified proteins is translin, which together with its binding partner TRAX supports RNA interference.

Structural and mutational analyses of cis-acting sequences in the 5'-untranslated region of satellite RNA of bamboo mosaic potexvirus

International Nuclear Information System (INIS)

Annamalai, Padmanaban; Hsu, Y.-H.; Liu, Y.-P.; Tsai, C.-H.; Lin, N.-S.

2003-01-01

The satellite RNA of Bamboo mosaic virus (satBaMV) contains on open reading frame for a 20-kDa protein that is flanked by a 5'-untranslated region (UTR) of 159 nucleotides (nt) and a 3'-UTR of 129 nt. A secondary structure was predicted for the 5'-UTR of satBaMV RNA, which folds into a large stem-loop (LSL) and a small stem-loop. Enzymatic probing confirmed the existence of LSL (nt 8-138) in the 5'-UTR. The essential cis-acting sequences in the 5'-UTR required for satBaMV RNA replication were determined by deletion and substitution mutagenesis. Their replication efficiencies were analyzed in Nicotiana benthamiana protoplasts and Chenopodium quinoa plants coinoculated with helper BaMV RNA. All deletion mutants abolished the replication of satBaMV RNA, whereas mutations introduced in most of the loop regions and stems showed either no replication or a decreased replication efficiency. Mutations that affected the positive-strand satBaMV RNA accumulation also affected the accumulation of negative-strand RNA; however, the accumulation of genomic and subgenomic RNAs of BaMV were not affected. Moreover, covariation analyses of natural satBaMV variants provide substantial evidence that the secondary structure in the 5'-UTR of satBaMV is necessary for efficient replication

Finding cancer driver mutations in the era of big data research.

Science.gov (United States)

Poulos, Rebecca C; Wong, Jason W H

2018-04-02

In the last decade, the costs of genome sequencing have decreased considerably. The commencement of large-scale cancer sequencing projects has enabled cancer genomics to join the big data revolution. One of the challenges still facing cancer genomics research is determining which are the driver mutations in an individual cancer, as these contribute only a small subset of the overall mutation profile of a tumour. Focusing primarily on somatic single nucleotide mutations in this review, we consider both coding and non-coding driver mutations, and discuss how such mutations might be identified from cancer sequencing datasets. We describe some of the tools and database that are available for the annotation of somatic variants and the identification of cancer driver genes. We also address the use of genome-wide variation in mutation load to establish background mutation rates from which to identify driver mutations under positive selection. Finally, we describe the ways in which mutational signatures can act as clues for the identification of cancer drivers, as these mutations may cause, or arise from, certain mutational processes. By defining the molecular changes responsible for driving cancer development, new cancer treatment strategies may be developed or novel preventative measures proposed.

Haplotype analysis suggest that the MLH1 c.2059C > T mutation is a Swedish founder mutation.

Science.gov (United States)

von Salomé, Jenny; Liu, Tao; Keihäs, Markku; Morak, Moni; Holinski-Feder, Elke; Berry, Ian R; Moilanen, Jukka S; Baert-Desurmont, Stéphanie; Lindblom, Annika; Lagerstedt-Robinson, Kristina

2017-12-29

Lynch syndrome (LS) predisposes to a spectrum of cancers and increases the lifetime risk of developing colorectal- or endometrial cancer to over 50%. Lynch syndrome is dominantly inherited and is caused by defects in DNA mismatch-repair genes MLH1, MSH2, MSH6 or PMS2, with the vast majority detected in MLH1 and MSH2. Recurrent LS-associated variants observed in apparently unrelated individuals, have either arisen de novo in different families due to mutation hotspots, or are inherited from a founder (a common ancestor) that lived several generations back. There are variants that recur in some populations while also acting as founders in other ethnic groups. Testing for founder mutations can facilitate molecular diagnosis of Lynch Syndrome more efficiently and more cost effective than screening for all possible mutations. Here we report a study of the missense mutation MLH1 c.2059C > T (p.Arg687Trp), a potential founder mutation identified in eight Swedish families and one Finnish family with Swedish ancestors. Haplotype analysis confirmed that the Finnish and Swedish families shared a haplotype of between 0.9 and 2.8 Mb. While MLH1 c.2059C > T exists worldwide, the Swedish haplotype was not found among mutation carriers from Germany or France, which indicates a common founder in the Swedish population. The geographic distribution of MLH1 c.2059C > T in Sweden suggests a single, ancient mutational event in the northern part of Sweden.

Suppressors of RNA silencing encoded by tomato leaf curl

Indian Academy of Sciences (India)

Whitefly-transmitted begomoviruses infecting tomato crop code for five different proteins, ORF AC4, ORF AC2 and ORF AV2 in DNA-A component, ORF BV1 in DNA-B ... In the present study suppressor function of ORF C1 of three betasatellites Tomato leaf curl Bangalore betasatellite ToLCBB-[IN:Hess:08], Cotton leaf curl ...

Germline CDKN2A/P16INK4A mutations contribute to genetic determinism of sarcoma.

Science.gov (United States)

Jouenne, Fanélie; Chauvot de Beauchene, Isaure; Bollaert, Emeline; Avril, Marie-Françoise; Caron, Olivier; Ingster, Olivier; Lecesne, Axel; Benusiglio, Patrick; Terrier, Philippe; Caumette, Vincent; Pissaloux, Daniel; de la Fouchardière, Arnaud; Cabaret, Odile; N'Diaye, Birama; Velghe, Amélie; Bougeard, Gaelle; Mann, Graham J; Koscielny, Serge; Barrett, Jennifer H; Harland, Mark; Newton-Bishop, Julia; Gruis, Nelleke; Van Doorn, Remco; Gauthier-Villars, Marion; Pierron, Gaelle; Stoppa-Lyonnet, Dominique; Coupier, Isabelle; Guimbaud, Rosine; Delnatte, Capucine; Scoazec, Jean-Yves; Eggermont, Alexander M; Feunteun, Jean; Tchertanov, Luba; Demoulin, Jean-Baptiste; Frebourg, Thierry; Bressac-de Paillerets, Brigitte

2017-09-01

Sarcomas are rare mesenchymal malignancies whose pathogenesis is poorly understood; both environmental and genetic risk factors could contribute to their aetiology. We performed whole-exome sequencing (WES) in a familial aggregation of three individuals affected with soft-tissue sarcoma (STS) without TP53 mutation (Li-Fraumeni-like, LFL) and found a shared pathogenic mutation in CDKN2A tumour suppressor gene. We searched for individuals with sarcoma among 474 melanoma-prone families with a CDKN2A -/+ genotype and for CDKN2A mutations in 190 TP53 -negative LFL families where the index case was a sarcoma. Including the initial family, eight independent sarcoma cases carried a germline mutation in the CDKN2A /p16 INK4A gene. In five out of seven formalin-fixed paraffin-embedded sarcomas, heterozygosity was lost at germline CDKN2A mutations sites demonstrating complete loss of function. As sarcomas are rare in CDKN2A /p16 INK4A carriers, we searched in constitutional WES of nine carriers for potential modifying rare variants and identified three in platelet-derived growth factor receptor ( PDGFRA ) gene. Molecular modelling showed that two never-described variants could impact the PDGFRA extracellular domain structure. Germline mutations in CDKN2A /P16 INK4A , a gene known to predispose to hereditary melanoma, pancreatic cancer and tobacco-related cancers, account also for a subset of hereditary sarcoma. In addition, we identified PDGFRA as a candidate modifier gene. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

Functional identification of an Arabidopsis snf4 ortholog by screening for heterologous multicopy suppressors of snf4 deficiency in yeast

DEFF Research Database (Denmark)

Kleinow, T.; Bhalerao, R.; Breuer, F.

2000-01-01

Yeast Snf4 is a prototype of activating gamma-subunits of conserved Snf1/AMPK-related protein kinases (SnRKs) controlling glucose and stress signaling in eukaryotes. The catalytic subunits of Arabidopsis SnRKs, AKIN10 and AKIN11, interact with Snf4 and suppress the snf1 and snf4 mutations in yeast....... By expression of an Arabidopsis cDNA library in yeast, heterologous multicopy snf4 suppressors were isolated. In addition to AKIN10 and AKIN11, the deficiency of yeast snf4 mutant to grown on non-fermentable carbon source was suppressed by Arabidopsis Myb30, CAAT-binding factor Hap3b, casein kinase I, zinc......-finger factors AZF2 and ZAT10, as well as orthologs of hexose/UDP-hexose transporters, calmodulin, SMC1-cohesin and Snf4. Here we describe the characterization of AtSNF4, a functional Arabidopsis Snf4 ortholog, that interacts with yeast Snf1 and specifically binds to the C-terminal regulatory domain...

Effect of bone marrow depletion on prostaglandin E-producing suppressor macrophages in mouse spleen

International Nuclear Information System (INIS)

Shibata, Y.; Volkman, A.

1985-01-01

The i.p. injection of Corynebacterium parvum (CP) into CBA/J mice effected increases in macrophage colony-forming cells (M-CFC) when spleen cells were cultured with L cell culture filtrate as a source of colony-stimulating factor. Significant increases in phagocytic macrophages (M phi) with Fc receptors for IgG2a and IgG2b immune complexes were additionally noted among the spleen cells in these mice. These M phi effectively inhibited Con A-induced lymphocyte proliferation, probably reflecting a 10-fold increase above normal controls in prostaglandin E to 47 ng/3 X 10(6) spleen cells/ml. To determine whether the suppressor M phi are immediate derivatives of splenic M-CFC, we tried to induce suppressor M phi by the injection of CP into mice depleted of bone marrow M-CFC by the earlier administration of the bone-seeking isotope, 89Sr. This procedure reduced M-CFC in the bone marrow to less than 1% of normal for more than 30 days. Monocytes in the blood fell to 5% of normal by day 10 and were 30% on day 30. Levels of resident peritoneal M phi showed relatively little change in this period. By contrast, splenic M-CFC increased to 20-fold higher than the cold 88Sr controls. CP-induced suppressor M phi activity, however, was sharply reduced in 89Sr marrow-depleted mice on day 10, despite the striking increase in M-CFC. There was a threefold increase in the number of phagocytic M phi binding IgG2a immune complexes, with no significant increase in IgG2b binding M phi. The kinetics of recovery of suppressor M phi activity showed that on days 20, 30, and 50 after 89Sr injection the activities reached 20%, 30%, and 70% of the cold control, respectively, and correlated with the recovery of significant levels of M-CFC in the bone marrow. Taken together, these observations suggest that splenic M-CFC are not an immediate source of PGE-suppressor M phi in vivo

Polymorphisms in Plasmodium falciparum K13-propeller in Angola and Mozambique after the introduction of the ACTs.

Science.gov (United States)

Escobar, Carlos; Pateira, Sara; Lobo, Elsa; Lobo, Lis; Teodosio, Rosa; Dias, Fernanda; Fernandes, Natercia; Arez, Ana Paula; Varandas, Luis; Nogueira, Fatima

2015-01-01

We report the presence of SNPs in Plasmodium falciparum K13-propeller gene in two African countries, Angola and Mozambique, where malaria is a serious public health problem. Samples were collected before and after ACT introduction as first-line treatment. In each country 50 samples collected before and 50 after ACT introduction were analysed. A total of three different mutations (R471R and R575R in Angola and V494I in Mozambique) were identified in five samples, all collected after the introduction of ACT. The R471R mutation detected in Angola has already been reported in Africa (DR-Congo and Gabon). However, the mutations R575R (Angola) and V494I (Mozambique), have never been reported. V494I is adjacent to the known K13 resistance-associated mutation Y493H, although functional analysis did not predict a deleterious effect on protein function.

Mutations in Plasmodium falciparum K13 propeller gene from Bangladesh (2009-2013).

Science.gov (United States)

Mohon, Abu Naser; Alam, Mohammad Shafiul; Bayih, Abebe Genetu; Folefoc, Asongna; Shahinas, Dea; Haque, Rashidul; Pillai, Dylan R

2014-11-18

Bangladesh is a malaria hypo-endemic country sharing borders with India and Myanmar. Artemisinin combination therapy (ACT) remains successful in Bangladesh. An increase of artemisinin-resistant malaria parasites on the Thai-Cambodia and Thai-Myanmar borders is worrisome. K13 propeller gene (PF3D7_1343700 or PF13_0238) mutations have been linked to both in vitro artemisinin resistance and in vivo slow parasite clearance rates. This group undertook to evaluate if mutations seen in Cambodia have emerged in Bangladesh where ACT use is now standard for a decade. Samples were obtained from Plasmodium falciparum-infected malaria patients from Upazila health complexes (UHC) between 2009 and 2013 in seven endemic districts of Bangladesh. These districts included Khagrachari (Matiranga UHC), Rangamati (Rajasthali UHC), Cox's Bazar (Ramu and Ukhia UHC), Bandarban (Lama UHC), Mymensingh (Haluaghat UHC), Netrokona (Durgapur and Kalmakanda UHC), and Moulvibazar (Sreemangal and Kamalganj UHC). Out of 296 microscopically positive P. falciparum samples, 271 (91.6%) were confirmed as mono-infections by both real-time PCR and nested PCR. The K13 propeller gene from 253 (93.4%) samples was sequenced bi-directionally. One non-synonymous mutation (A578S) was found in Bangladeshi clinical isolates. The A578S mutation was confirmed and lies adjacent to the C580Y mutation, the major mutation causing delayed parasite clearance in Cambodia. Based on computational modeling A578S should have a significant effect on tertiary structure of the protein. The data suggest that P. falciparum in Bangladesh remains free of the C580Y mutation linked to delayed parasite clearance. However, the mutation A578S is present and based on structural analysis could affect K13 gene function. Further in vivo clinical studies are required to validate the effect of this mutation.

Subpopulation of human helper and suppressor T lymphocytes

International Nuclear Information System (INIS)

Venkataraman, M.; Levin, R.D.; Westerman, M.P.

1983-01-01

Mitogen driven differentiation of normal human mononuclear cells is a well-established model for the study of antibody synthesis in man. In certain rare individuals who are clinically normal, unfractionated mononuclear cells or a mixture of purified B plus T lymphocytes differentiate into immunoglobulin producing cells in response to purified protein derivative of tuberculin (PPD) but not in response to pokeweed mitogen (PWM). To evaluate this observation we have irradiated T cells from such individuals to eliminate naturally occurring suppressor T cell activity and then added the irradiated T cells back to autologous B cells before culture. The B cells then responded to PWM. The original PPD responses of cells from these individuals were now significantly reduced. Although, there was no difference between PWM nonresponders and responders in the number of OKT-8 positive cells, elimination of OKT-8 positive cells in the PWM nonresponders with OKT-8 monoclonal antibody and complement resulted in a significantly increased response to PWM. This study indicates that there are suppressor T cells which specifically inhibit B cell response to PWM without affecting the PPD response. These results also show that the helper T cells involved in the PWM response are radioresistant and those involved in the PPD response are radiosensitive

Simple mathematical method to quantify p53 mutations in occupational lung cancer

International Nuclear Information System (INIS)

Helal, N.L.

2005-01-01

Radon-222, a decay product of uranium-238 and a source of high linear energy transfer (LET) alpha -particles, has been implicated in the increase risk of lung cancer in uranium miners as well as non-miners. The p53 gene mutational spectrum reveals evidence for a direct causal effect of radon inhalation in lung cancer. This mutation has been proposed as a marker of radon exposure. The development of such markers may ultimately be of benefit in the reduction of occupational morbidity and mortality from occupational cancer. One of the tasks in risk assessment of genotoxic occupational radiation exposure is to devise a simple numerical method. This method may be used to quantify the relationship between radiation dose and the effect on the genetic sequences. The tumor suppressor gene (TSG) p53 is an ideal bio marker addressing questions of exposure and risk. These proteins may be suitable for the design of more effective or less invasive cancer therapies. The clinical outcome of lung cancer patients may correlate with the normal regulation of these patients and, therefore, their identification may be used as a guideline for future therapy modalities. To investigate the association between radon exposure and p53 mutations in lung tumors, we have implied a mathematical method. This method has been developed from a 2-D graphical representational technique that enables easy visualization of base distributions. This is of special relevance to libraries of single nucleotide polymorphic (SNP) genes

Unique mutational profile associated with a loss of TDG expression in the rectal cancer of a patient with a constitutional PMS2 deficiency.

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Vasovcak, P; Krepelova, A; Menigatti, M; Puchmajerova, A; Skapa, P; Augustinakova, A; Amann, G; Wernstedt, A; Jiricny, J; Marra, G; Wimmer, K

2012-07-01

Cells with DNA repair defects have increased genomic instability and are more likely to acquire secondary mutations that bring about cellular transformation. We describe the frequency and spectrum of somatic mutations involving several tumor suppressor genes in the rectal carcinoma of a 13-year-old girl harboring biallelic, germline mutations in the DNA mismatch repair gene PMS2. Apart from microsatellite instability, the tumor DNA contained a number of C:G→T:A or G:C→A:T transitions in CpG dinucleotides, which often result through spontaneous deamination of cytosine or 5-methylcytosine. Four DNA glycosylases, UNG2, SMUG1, MBD4 and TDG, are involved in the repair of these deamination events. We identified a heterozygous missense mutation in TDG, which was associated with TDG protein loss in the tumor. The CpGs mutated in this patient's tumor are generally methylated in normal colonic mucosa. Thus, it is highly likely that loss of TDG contributed to the supermutator phenotype and that most of the point mutations were caused by deamination of 5-methylcytosine to thymine, which remained uncorrected owing to the TDG deficiency. This case provides the first in vivo evidence of the key role of TDG in protecting the human genome against the deleterious effects of 5-methylcytosine deamination. Copyright © 2012 Elsevier B.V. All rights reserved.

TFPI-2 is a putative tumor suppressor gene frequently inactivated by promoter hypermethylation in nasopharyngeal carcinoma

International Nuclear Information System (INIS)

Wang, Shumin; Ma, Ning; Murata, Mariko; Huang, Guangwu; Zhang, Zhe; Xiao, Xue; Zhou, Xiaoying; Huang, Tingting; Du, Chunping; Yu, Nana; Mo, Yingxi; Lin, Longde; Zhang, Jinyan

2010-01-01

Epigenetic silencing of tumor suppressor genes play important roles in NPC tumorgenesis. Tissue factor pathway inhibitor-2 (TFPI-2), is a protease inhibitor. Recently, TFPI-2 was suggested to be a tumor suppressor gene involved in tumorigenesis and metastasis in some cancers. In this study, we investigated whether TFPI-2 was inactivated epigenetically in nasopharyngeal carcinoma (NPC). Transcriptional expression levels of TFPI-2 was evaluated by RT-PCR. Methylation status were investigated by methylation specific PCR and bisulfate genomic sequencing. The role of TFPI-2 as a tumor suppressor gene in NPC was addressed by re-introducing TFPI-2 expression into the NPC cell line CNE2. TFPI-2 mRNA transcription was inactivated in NPC cell lines. TFPI-2 was aberrantly methylated in 66.7% (4/6) NPC cell lines and 88.6% (62/70) of NPC primary tumors, but not in normal nasopharyngeal epithelia. TFPI-2 expression could be restored in NPC cells after demethylation treatment. Ectopic expression of TFPI-2 in NPC cells induced apoptosis and inhibited cell proliferation, colony formation and cell migration. Epigenetic inactivation of TFPI-2 by promoter hypermethylation is a frequent and tumor specific event in NPC. TFPI-2 might be considering as a putative tumor suppressor gene in NPC

The role of UV induced lesions in skin carcinogenesis: an overview of oncogene and tumor suppressor gene modifications in xeroderma pigmentosum skin tumors

International Nuclear Information System (INIS)

Daya-Grosjean, Leela; Sarasin, Alain

2005-01-01

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

The role of UV induced lesions in skin carcinogenesis: an overview of oncogene and tumor suppressor gene modifications in xeroderma pigmentosum skin tumors

Energy Technology Data Exchange (ETDEWEB)

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.

Mutations affecting RNA polymerase I-stimulated exchange and rDNA recombination in yeast

International Nuclear Information System (INIS)

Lin, Y.H.; Keil, R.L.

1991-01-01

HOT1 is a cis-acting recombination-stimulatory sequence isolated from the rDNA repeat unit of yeast. The ability of HOT1 to stimulate mitotic exchange appears to depend on its ability to promote high levels of RNA polymerase I transcription. A qualitative colony color sectoring assay was developed to screen for trans-acting mutations that alter the activity of HOT1. Both hypo-recombination and hyper-recombination mutants were isolated. Genetic analysis of seven HOT1 recombination mutants (hrm) that decrease HOT1 activity shows that they behave as recessive nuclear mutations and belong to five linkage groups. Three of these mutations, hrm1, hrm2, and hrm3, also decrease rDNA exchange but do not alter recombination in the absence of HOT1. Another mutation, hrm4, decreases HOT1-stimulated recombination but does not affect rDNA recombination or exchange in the absence of HOT1. Two new alleles of RAD52 were also isolated using this screen. With regard to HOT1 activity, rad52 is epistatic to all four hrm mutations indicating that the products of the HRM genes and of RAD52 mediate steps in the same recombination pathway. Finding mutations that decrease both the activity of HOT1 and exchange in the rDNA supports the hypothesis that HOT1 plays a role in rDNA recombination

History of myeloid-derived suppressor cells.

Science.gov (United States)

Talmadge, James E; Gabrilovich, Dmitry I

2013-10-01

Tumour-induced granulocytic hyperplasia is associated with tumour vasculogenesis and escape from immunity via T cell suppression. Initially, these myeloid cells were identified as granulocytes or monocytes; however, recent studies have revealed that this hyperplasia is associated with populations of multipotent progenitor cells that have been identified as myeloid-derived suppressor cells (MDSCs). The study of MDSCs has provided a wealth of information regarding tumour pathobiology, has extended our understanding of neoplastic progression and has modified our approaches to immune adjuvant therapy. In this Timeline article, we discuss the history of MDSCs, their influence on tumour progression and metastasis, and the crosstalk between tumour cells, MDSCs and the host macroenvironment.

Alterations in tumour suppressor gene p53 in human gliomas from ...

Indian Academy of Sciences (India)

Unknown

Alterations in the tumour suppressor p53 gene are among the most common defects seen in a variety of human cancers. ..... rangement of the EGF receptor gene in primary human brain tumors ... the INK4A gene in superficial bladder tumors.

Transducer of ERBB2.1 (TOB1) as a Tumor Suppressor: A Mechanistic Perspective.

Science.gov (United States)

Lee, Hun Seok; Kundu, Juthika; Kim, Ryong Nam; Shin, Young Kee

2015-12-15

Transducer of ERBB2.1 (TOB1) is a tumor-suppressor protein, which functions as a negative regulator of the receptor tyrosine-kinase ERBB2. As most of the other tumor suppressor proteins, TOB1 is inactivated in many human cancers. Homozygous deletion of TOB1 in mice is reported to be responsible for cancer development in the lung, liver, and lymph node, whereas the ectopic overexpression of TOB1 shows anti-proliferation, and a decrease in the migration and invasion abilities on cancer cells. Biochemical studies revealed that the anti-proliferative activity of TOB1 involves mRNA deadenylation and is associated with the reduction of both cyclin D1 and cyclin-dependent kinase (CDK) expressions and the induction of CDK inhibitors. Moreover, TOB1 interacts with an oncogenic signaling mediator, β-catenin, and inhibits β-catenin-regulated gene transcription. TOB1 antagonizes the v-akt murine thymoma viral oncogene (AKT) signaling and induces cancer cell apoptosis by activating BCL2-associated X (BAX) protein and inhibiting the BCL-2 and BCL-XL expressions. The tumor-specific overexpression of TOB1 results in the activation of other tumor suppressor proteins, such as mothers against decapentaplegic homolog 4 (SMAD4) and phosphatase and tensin homolog-10 (PTEN), and blocks tumor progression. TOB1-overexpressing cancer cells have limited potential of growing as xenograft tumors in nude mice upon subcutaneous implantation. This review addresses the molecular basis of TOB1 tumor suppressor function with special emphasis on its regulation of intracellular signaling pathways.

Transducer of ERBB2.1 (TOB1 as a Tumor Suppressor: A Mechanistic Perspective

Directory of Open Access Journals (Sweden)

Hun Seok Lee

2015-12-01

Full Text Available Transducer of ERBB2.1 (TOB1 is a tumor-suppressor protein, which functions as a negative regulator of the receptor tyrosine-kinase ERBB2. As most of the other tumor suppressor proteins, TOB1 is inactivated in many human cancers. Homozygous deletion of TOB1 in mice is reported to be responsible for cancer development in the lung, liver, and lymph node, whereas the ectopic overexpression of TOB1 shows anti-proliferation, and a decrease in the migration and invasion abilities on cancer cells. Biochemical studies revealed that the anti-proliferative activity of TOB1 involves mRNA deadenylation and is associated with the reduction of both cyclin D1 and cyclin-dependent kinase (CDK expressions and the induction of CDK inhibitors. Moreover, TOB1 interacts with an oncogenic signaling mediator, β-catenin, and inhibits β-catenin-regulated gene transcription. TOB1 antagonizes the v-akt murine thymoma viral oncogene (AKT signaling and induces cancer cell apoptosis by activating BCL2-associated X (BAX protein and inhibiting the BCL-2 and BCL-XL expressions. The tumor-specific overexpression of TOB1 results in the activation of other tumor suppressor proteins, such as mothers against decapentaplegic homolog 4 (SMAD4 and phosphatase and tensin homolog-10 (PTEN, and blocks tumor progression. TOB1-overexpressing cancer cells have limited potential of growing as xenograft tumors in nude mice upon subcutaneous implantation. This review addresses the molecular basis of TOB1 tumor suppressor function with special emphasis on its regulation of intracellular signaling pathways.

Promoter Methylation Analysis of IDH Genes in Human Gliomas

International Nuclear Information System (INIS)

Flanagan, Simon; Lee, Maggie; Li, Cheryl C. Y.; Suter, Catherine M.; Buckland, Michael E.

2012-01-01

Mutations in isocitrate dehydrogenase (IDH)-1 or -2 are found in the majority of WHO grade II and III astrocytomas and oligodendrogliomas, and secondary glioblastomas. Almost all described mutations are heterozygous missense mutations affecting a conserved arginine residue in the substrate binding site of IDH1 (R132) or IDH2 (R172). But the exact mechanism of IDH mutations in neoplasia is not understood. It has been proposed that IDH mutations impart a “toxic gain-of-function” to the mutant protein, however a dominant-negative effect of mutant IDH has also been described, implying that IDH may function as a tumor suppressor gene. As most, if not all, tumor suppressor genes are inactivated by epigenetic silencing, in a wide variety of tumors, we asked if IDH1 or IDH2 carry the epigenetic signature of a tumor suppressor by assessing cytosine methylation at their promoters. Methylation was quantified in 68 human brain tumors, including both IDH-mutant and IDH wildtype, by bisulfite pyrosequencing. In all tumors examined, CpG methylation levels were less than 8%. Our data demonstrate that inactivation of IDH function through promoter hypermethylation is not common in human gliomas and other brain tumors. These findings do not support a tumor suppressor role for IDH genes in human gliomas.

Mimic Phosphorylation of a βC1 Protein Encoded by TYLCCNB Impairs Its Functions as a Viral Suppressor of RNA Silencing and a Symptom Determinant.

Science.gov (United States)

Zhong, Xueting; Wang, Zhan Qi; Xiao, Ruyuan; Cao, Linge; Wang, Yaqin; Xie, Yan; Zhou, Xueping

2017-08-15

Phosphorylation of the βC1 protein encoded by the betasatellite of tomato yellow leaf curl China virus (TYLCCNB-βC1) by SNF1-related protein kinase 1 (SnRK1) plays a critical role in defense of host plants against geminivirus infection in Nicotiana benthamiana However, how phosphorylation of TYLCCNB-βC1 impacts its pathogenic functions during viral infection remains elusive. In this study, we identified two additional tyrosine residues in TYLCCNB-βC1 that are phosphorylated by SnRK1. The effects of TYLCCNB-βC1 phosphorylation on its functions as a viral suppressor of RNA silencing (VSR) and a symptom determinant were investigated via phosphorylation mimic mutants in N. benthamiana plants. Mutations that mimic phosphorylation of TYLCCNB-βC1 at tyrosine 5 and tyrosine 110 attenuated disease symptoms during viral infection. The phosphorylation mimics weakened the ability of TYLCCNB-βC1 to reverse transcriptional gene silencing and to suppress posttranscriptional gene silencing and abolished its interaction with N. benthamiana ASYMMETRIC LEAVES 1 in N. benthamiana leaves. The mimic phosphorylation of TYLCCNB-βC1 had no impact on its protein stability, subcellular localization, or self-association. Our data establish an inhibitory effect of phosphorylation of TYLCCNB-βC1 on its pathogenic functions as a VSR and a symptom determinant and provide a mechanistic explanation of how SnRK1 functions as a host defense factor. IMPORTANCE Tomato yellow leaf curl China virus (TYLCCNV), which causes a severe yellow leaf curl disease in China, is a monopartite geminivirus associated with the betasatellite (TYLCCNB). TYLCCNB encodes a single pathogenicity protein, βC1 (TYLCCNB-βC1), which functions as both a viral suppressor of RNA silencing (VSR) and a symptom determinant. Here, we show that mimicking phosphorylation of TYLCCNB-βC1 weakens its ability to reverse transcriptional gene silencing, to suppress posttranscriptional gene silencing, and to interact with N

Clinical impact of the immunome in lymphoid malignancies: the role of Myeloid-Derived Suppressor Cells

Directory of Open Access Journals (Sweden)

Calogero eVetro

2015-05-01

Full Text Available The better definition of the mutual sustainment between neoplastic cells and immune system has been translated from the bench to the bedside acquiring value as prognostic factor. Additionally, it represents a promising tool for improving therapeutic strategies. In this context, myeloid-derived suppressor cells have gained a central role in tumor developing with consequent therapeutic implications. In this review, we will focus on the biological and clinical impact of the study of myeloid-derived suppressor cells in the settings of lymphoid malignancies.

Fate of a mutation in a fluctuating environment

Science.gov (United States)

Cvijović, Ivana; Good, Benjamin H.; Jerison, Elizabeth R.; Desai, Michael M.

2015-01-01

Natural environments are never truly constant, but the evolutionary implications of temporally varying selection pressures remain poorly understood. Here we investigate how the fate of a new mutation in a fluctuating environment depends on the dynamics of environmental variation and on the selective pressures in each condition. We find that even when a mutation experiences many environmental epochs before fixing or going extinct, its fate is not necessarily determined by its time-averaged selective effect. Instead, environmental variability reduces the efficiency of selection across a broad parameter regime, rendering selection unable to distinguish between mutations that are substantially beneficial and substantially deleterious on average. Temporal fluctuations can also dramatically increase fixation probabilities, often making the details of these fluctuations more important than the average selection pressures acting on each new mutation. For example, mutations that result in a trade-off between conditions but are strongly deleterious on average can nevertheless be more likely to fix than mutations that are always neutral or beneficial. These effects can have important implications for patterns of molecular evolution in variable environments, and they suggest that it may often be difficult for populations to maintain specialist traits, even when their loss leads to a decline in time-averaged fitness. PMID:26305937

Impact of low-frequency hotspot mutation R282Q on the structure of p53 DNA-binding domain as revealed by crystallography at 1.54 Å resolution

Energy Technology Data Exchange (ETDEWEB)

Tu, Chao [Macromolecular Crystallography Laboratory, National Cancer Institute, Frederick, MD 21702 (United States); Tan, Yu-Hong [Department of Molecular Biology and Biochemistry, University of California at Irvine, Irvine, CA 92697 (United States); Shaw, Gary [Macromolecular Crystallography Laboratory, National Cancer Institute, Frederick, MD 21702 (United States); Zhou, Zheng; Bai, Yawen [Laboratory of Biochemistry and Molecular Biology, National Cancer Institute, Bethesda, MD 20892 (United States); Luo, Ray [Department of Molecular Biology and Biochemistry, University of California at Irvine, Irvine, CA 92697 (United States); Ji, Xinhua, E-mail: jix@ncifcrf.gov [Macromolecular Crystallography Laboratory, National Cancer Institute, Frederick, MD 21702 (United States)

2008-05-01

The impact of hotspot mutation R282Q on the structure of human p53 DNA-binding domain has been characterized by X-ray crystallography and molecular-dynamics simulations. Tumor suppressor p53 is a sequence-specific DNA-binding protein and its central DNA-binding domain (DBD) harbors six hotspots (Arg175, Gly245, Arg248, Arg249, Arg273 and Arg282) for human cancers. Here, the crystal structure of a low-frequency hotspot mutant, p53DBD(R282Q), is reported at 1.54 Å resolution together with the results of molecular-dynamics simulations on the basis of the structure. In addition to eliminating a salt bridge, the R282Q mutation has a significant impact on the properties of two DNA-binding loops (L1 and L3). The L1 loop is flexible in the wild type, but it is not flexible in the mutant. The L3 loop of the wild type is not flexible, whereas it assumes two conformations in the mutant. Molecular-dynamics simulations indicated that both conformations of the L3 loop are accessible under biological conditions. It is predicted that the elimination of the salt bridge and the inversion of the flexibility of L1 and L3 are directly or indirectly responsible for deactivating the tumor suppressor p53.

Identification of a maize chlorotic dwarf virus silencing suppressor protein

Science.gov (United States)

Maize chlorotic dwarf virus (MCDV), a member of the genus Waikavirus, family Secoviridae, has a 11784 nt (+)ssRNA genome that encodes a 389 kDa proteolytically processed polyprotein. We show that an N-terminal 78kDa polyprotein (R78) has silencing suppressor activity, that it is cleaved by the viral...

High mutation rates limit evolutionary adaptation in Escherichia coli.

Directory of Open Access Journals (Sweden)

Kathleen Sprouffske

2018-04-01

Full Text Available Mutation is fundamental to evolution, because it generates the genetic variation on which selection can act. In nature, genetic changes often increase the mutation rate in systems that range from viruses and bacteria to human tumors. Such an increase promotes the accumulation of frequent deleterious or neutral alleles, but it can also increase the chances that a population acquires rare beneficial alleles. Here, we study how up to 100-fold increases in Escherichia coli's genomic mutation rate affect adaptive evolution. To do so, we evolved multiple replicate populations of asexual E. coli strains engineered to have four different mutation rates for 3000 generations in the laboratory. We measured the ability of evolved populations to grow in their original environment and in more than 90 novel chemical environments. In addition, we subjected the populations to whole genome population sequencing. Although populations with higher mutation rates accumulated greater genetic diversity, this diversity conveyed benefits only for modestly increased mutation rates, where populations adapted faster and also thrived better than their ancestors in some novel environments. In contrast, some populations at the highest mutation rates showed reduced adaptation during evolution, and failed to thrive in all of the 90 alternative environments. In addition, they experienced a dramatic decrease in mutation rate. Our work demonstrates that the mutation rate changes the global balance between deleterious and beneficial mutational effects on fitness. In contrast to most theoretical models, our experiments suggest that this tipping point already occurs at the modest mutation rates that are found in the wild.

High mutation rates limit evolutionary adaptation in Escherichia coli

Science.gov (United States)

Wagner, Andreas

2018-01-01

Mutation is fundamental to evolution, because it generates the genetic variation on which selection can act. In nature, genetic changes often increase the mutation rate in systems that range from viruses and bacteria to human tumors. Such an increase promotes the accumulation of frequent deleterious or neutral alleles, but it can also increase the chances that a population acquires rare beneficial alleles. Here, we study how up to 100-fold increases in Escherichia coli’s genomic mutation rate affect adaptive evolution. To do so, we evolved multiple replicate populations of asexual E. coli strains engineered to have four different mutation rates for 3000 generations in the laboratory. We measured the ability of evolved populations to grow in their original environment and in more than 90 novel chemical environments. In addition, we subjected the populations to whole genome population sequencing. Although populations with higher mutation rates accumulated greater genetic diversity, this diversity conveyed benefits only for modestly increased mutation rates, where populations adapted faster and also thrived better than their ancestors in some novel environments. In contrast, some populations at the highest mutation rates showed reduced adaptation during evolution, and failed to thrive in all of the 90 alternative environments. In addition, they experienced a dramatic decrease in mutation rate. Our work demonstrates that the mutation rate changes the global balance between deleterious and beneficial mutational effects on fitness. In contrast to most theoretical models, our experiments suggest that this tipping point already occurs at the modest mutation rates that are found in the wild. PMID:29702649

Mutations of the Birt–Hogg–Dubé gene in patients with multiple lung cysts and recurrent pneumothorax

Science.gov (United States)

Gunji, Yoko; Akiyoshi, Taeko; Sato, Teruhiko; Kurihara, Masatoshi; Tominaga, Shigeru; Takahashi, Kazuhisa; Seyama, Kuniaki

2007-01-01

Rationale Birt–Hogg–Dubé (BHD) syndrome, a rare inherited autosomal genodermatosis first recognised in 1977, is characterised by fibrofolliculomas of the skin, an increased risk of renal tumours and multiple lung cysts with spontaneous pneumothorax. The BHD gene, a tumour suppressor gene located at chromosome 17p11.2, has recently been shown to be defective. Recent genetic studies revealed that clinical pictures of the disease may be variable and may not always present the full expression of the phenotypes. Objectives We hypothesised that mutations of the BHD gene are responsible for patients who have multiple lung cysts of which the underlying causes have not yet been elucidated. Methods We studied eight patients with lung cysts, without skin and renal disease; seven of these patients have a history of spontaneous pneumothorax and five have a family history of pneumothorax. The BHD gene was examined using PCR, denaturing high‐performance liquid chromatography and direct sequencing. Main results We found that five of the eight patients had a BHD germline mutation. All mutations were unique and four of them were novel, including three different deletions or insertions detected in exons 6, 12 and 13, respectively and one splice acceptor site mutation in intron 5 resulting in an in‐frame deletion of exon 6. Conclusions We found that germline mutations of the BHD gene are involved in some patients with multiple lung cysts and pneumothorax. Pulmonologists should be aware that BHD syndrome can occur as an isolated phenotype with pulmonary involvement. PMID:17496196

Clonal composition of human ovarian cancer based on copy number analysis reveals a reciprocal relation with oncogenic mutation status.

Science.gov (United States)

Sakai, Kazuko; Ukita, Masayo; Schmidt, Jeanette; Wu, Longyang; De Velasco, Marco A; Roter, Alan; Jevons, Luis; Nishio, Kazuto; Mandai, Masaki

2017-10-01

Intratumoral heterogeneity of cancer cells remains largely unexplored. Here we investigated the composition of ovarian cancer and its biological relevance. A whole-genome single nucleotide polymorphism array was applied to detect the clonal composition of 24 formalin-fixed, paraffin-embedded samples of human ovarian cancer. Genome-wide segmentation data consisting of the log2 ratio (log2R) and B allele frequency (BAF) were used to calculate an estimate of the clonal composition number (CC number) for each tumor. Somatic mutation profiles of cancer-related genes were also determined for the same 24 samples by next-generation sequencing. The CC number was estimated successfully for 23 of the 24 cancer samples. The mean ± SD value for the CC number was 1.7 ± 1.1 (range of 0-4). A somatic mutation in at least one gene was identified in 22 of the 24 ovarian cancer samples, with the mutations including those in the oncogenes KRAS (29.2%), PIK3CA (12.5%), BRAF (8.3%), FGFR2 (4.2%), and JAK2 (4.2%) as well as those in the tumor suppressor genes TP53 (54.2%), FBXW7 (8.3%), PTEN (4.2%), and RB1 (4.2%). Tumors with one or more oncogenic mutations had a significantly lower CC number than did those without such a mutation (1.0 ± 0.8 versus 2.3 ± 0.9, P = 0.0027), suggesting that cancers with driver oncogene mutations are less heterogeneous than those with other mutations. Our results thus reveal a reciprocal relation between oncogenic mutation status and clonal composition in ovarian cancer using the established method for the estimation of the CC number. Copyright © 2017 The Author(s). Published by Elsevier B.V. All rights reserved.

Sucrose and IQ induced mutations in rat colon by independent

DEFF Research Database (Denmark)

Hansen, Max; Hald, M. T.; Autrup, H.

2004-01-01

Sucrose-rich diets have repeatedly been observed to have co-carcinogenic actions in colon and liver of rats and to increase the number of 2-amino-3-methylimidazo[4,5-f]quinoline (IQ) induced aberrant crypt foci in rat colon. To investigate a possible interaction between sucrose and IQ...... on the genotoxicity in rat liver and colon, we gave Big Blue rats(TM) a diet containing sucrose (0%, 3.45% or 13.4% w/w) and/or IQ (70 ppm) for a period of 3 weeks. Sucrose and IQ increased the mutation frequency in the colon. The effect of combined treatments with IQ and sucrose on the mutation frequencies...... was additive indicating that sucrose and IQ act independently. This was supported by the mutation spectra where sucrose expands the background mutations in the colon, whereas IQ, in other studies, more specifically has induced G:C --> T:A transversions. In the liver IQ increased the mutation frequency, whereas...

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

Energy Technology Data Exchange (ETDEWEB)

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.

Reciprocal sign epistasis between frequently experimentally evolved adaptive mutations causes a rugged fitness landscape.

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Daniel J Kvitek

2011-04-01

Full Text Available The fitness landscape captures the relationship between genotype and evolutionary fitness and is a pervasive metaphor used to describe the possible evolutionary trajectories of adaptation. However, little is known about the actual shape of fitness landscapes, including whether valleys of low fitness create local fitness optima, acting as barriers to adaptive change. Here we provide evidence of a rugged molecular fitness landscape arising during an evolution experiment in an asexual population of Saccharomyces cerevisiae. We identify the mutations that arose during the evolution using whole-genome sequencing and use competitive fitness assays to describe the mutations individually responsible for adaptation. In addition, we find that a fitness valley between two adaptive mutations in the genes MTH1 and HXT6/HXT7 is caused by reciprocal sign epistasis, where the fitness cost of the double mutant prohibits the two mutations from being selected in the same genetic background. The constraint enforced by reciprocal sign epistasis causes the mutations to remain mutually exclusive during the experiment, even though adaptive mutations in these two genes occur several times in independent lineages during the experiment. Our results show that epistasis plays a key role during adaptation and that inter-genic interactions can act as barriers between adaptive solutions. These results also provide a new interpretation on the classic Dobzhansky-Muller model of reproductive isolation and display some surprising parallels with mutations in genes often associated with tumors.

A genome-wide shRNA screen identifies GAS1 as a novel melanoma metastasis suppressor gene.

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Gobeil, Stephane; Zhu, Xiaochun; Doillon, Charles J; Green, Michael R

2008-11-01

Metastasis suppressor genes inhibit one or more steps required for metastasis without affecting primary tumor formation. Due to the complexity of the metastatic process, the development of experimental approaches for identifying genes involved in metastasis prevention has been challenging. Here we describe a genome-wide RNAi screening strategy to identify candidate metastasis suppressor genes. Following expression in weakly metastatic B16-F0 mouse melanoma cells, shRNAs were selected based upon enhanced satellite colony formation in a three-dimensional cell culture system and confirmed in a mouse experimental metastasis assay. Using this approach we discovered 22 genes whose knockdown increased metastasis without affecting primary tumor growth. We focused on one of these genes, Gas1 (Growth arrest-specific 1), because we found that it was substantially down-regulated in highly metastatic B16-F10 melanoma cells, which contributed to the high metastatic potential of this mouse cell line. We further demonstrated that Gas1 has all the expected properties of a melanoma tumor suppressor including: suppression of metastasis in a spontaneous metastasis assay, promotion of apoptosis following dissemination of cells to secondary sites, and frequent down-regulation in human melanoma metastasis-derived cell lines and metastatic tumor samples. Thus, we developed a genome-wide shRNA screening strategy that enables the discovery of new metastasis suppressor genes.

Mutational spectrum analysis of umuC-independent and umuC-dependent γ-radiation mutagenesis in Escherichia coli

International Nuclear Information System (INIS)

Sargentini, N.J.; Smith, K.C.

1989-01-01

γ-radiation mutagenesis Escherichia coli K-12. Mutagenesis (argE3(OC) A rg + ) was blocked in a δ(recA-srlR)306 strain at the same doses that induced mutations in umuC122::Tn5 and wild-type strains, indicating that both umuC-independent and umuC-dependent mechanisms function within recA-dependent misrepair. Analyses of various suppressor and back mutations that result in argE3 and hisG4 ochre reversion and an analysis of trpE9777 reversion were performed on umuC and wild-type cells irradiated in the presence and absence of oxygen. While the umuC strain showed the γ-radiation induction of base substitution and frameshifts when irradiated in the absence of oxygen, the umuC mutation blocked all oxygen-dependent base-substitution mutagenesis, but non all oxygen-dependent frameshift mutagenesis. For anoxically irradiated cells, the yields of GC T and AT GC transitions were essentially umuC independent, while the yields of (AT or GC) TA transversions were heavily umuC dependent. These data suggest new concepts about the nature of the DNA lesions and the mutagenic mechanisms that lead to γ-radiation mutagenesis. (author). 48 refs.; 1 tab.; 6 refs

Lethal giant larvae 1 tumour suppressor activity is not conserved in models of mammalian T and B cell leukaemia.

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Edwin D Hawkins

Full Text Available In epithelial and stem cells, lethal giant larvae (Lgl is a potent tumour suppressor, a regulator of Notch signalling, and a mediator of cell fate via asymmetric cell division. Recent evidence suggests that the function of Lgl is conserved in mammalian haematopoietic stem cells and implies a contribution to haematological malignancies. To date, direct measurement of the effect of Lgl expression on malignancies of the haematopoietic lineage has not been tested. In Lgl1⁻/⁻ mice, we analysed the development of haematopoietic malignancies either alone, or in the presence of common oncogenic lesions. We show that in the absence of Lgl1, production of mature white blood cell lineages and long-term survival of mice are not affected. Additionally, loss of Lgl1 does not alter leukaemia driven by constitutive Notch, c-Myc or Jak2 signalling. These results suggest that the role of Lgl1 in the haematopoietic lineage might be restricted to specific co-operating mutations and a limited number of cellular contexts.

Lethal Giant Larvae 1 Tumour Suppressor Activity Is Not Conserved in Models of Mammalian T and B Cell Leukaemia

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Hawkins, Edwin D.; Oliaro, Jane; Ramsbottom, Kelly M.; Ting, Stephen B.; Sacirbegovic, Faruk; Harvey, Michael; Kinwell, Tanja; Ghysdael, Jacques; Johnstone, Ricky W.; Humbert, Patrick O.; Russell, Sarah M.

2014-01-01

In epithelial and stem cells, lethal giant larvae (Lgl) is a potent tumour suppressor, a regulator of Notch signalling, and a mediator of cell fate via asymmetric cell division. Recent evidence suggests that the function of Lgl is conserved in mammalian haematopoietic stem cells and implies a contribution to haematological malignancies. To date, direct measurement of the effect of Lgl expression on malignancies of the haematopoietic lineage has not been tested. In Lgl1−/− mice, we analysed the development of haematopoietic malignancies either alone, or in the presence of common oncogenic lesions. We show that in the absence of Lgl1, production of mature white blood cell lineages and long-term survival of mice are not affected. Additionally, loss of Lgl1 does not alter leukaemia driven by constitutive Notch, c-Myc or Jak2 signalling. These results suggest that the role of Lgl1 in the haematopoietic lineage might be restricted to specific co-operating mutations and a limited number of cellular contexts. PMID:24475281

Problems in mechanistic theoretical models for cell transformation by ionizing radiation

International Nuclear Information System (INIS)

Chatterjee, Aloke; Holley, W.R.

1992-01-01

A mechanistic model based on yields of double strand breaks has been developed to determine the dose response curves for cell transformation frequencies. At its present stage the model is applicable to immortal cell lines and to various qualities (X-rays, Neon and Iron) of ionizing radiation. Presently, we have considered four types of processes which can lead to activation phenomena: (i) point mutation events on a regulatory segment of selected oncogenes, (ii) inactivation of suppressor genes, through point mutation, (iii) deletion of a suppressor gene by a single track, and (iv) deletion of a suppressor gene by two tracks. (author)

Should all patients with hyperparathyroidism be screened for a CDC73 mutation?

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Caroline Bachmeier

2018-03-01

Full Text Available Primary hyperparathyroidism (PH is a common endocrine abnormality and may occur as part of a genetic syndrome. Inactivating mutations of the tumour suppressor gene CDC73 have been identified as accounting for a large percentage of hyperparathyroidism-jaw tumour syndrome (HPT-JT cases and to a lesser degree account for familial isolated hyperparathyroidism (FIHP cases. Reports of CDC73 whole gene deletions are exceedingly rare. We report the case of a 39 year-old woman with PH secondary to a parathyroid adenoma associated with a large chromosomal deletion (2.5 Mb encompassing the entire CDC73 gene detected years after parathyroidectomy. This case highlights the necessity to screen young patients with hyperparathyroidism for an underlying genetic aetiology. It also demonstrates that molecular testing for this disorder should contain techniques that can detect large deletions.

Characterization of a mutant of Escherichia coli B/R defective in mutation frequency decline

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George, D.L.

1974-01-01

A mutant of Escherichia coli B/r designated mfd is very deficient in the ability to exhibit mutation frequency decline (MFD), the characteristic loss of potential suppressor mutations which occurs when protein synthesis is briefly inhibited after irradiation with ultraviolet light (uv). This mutant is known to excise pyrimidine dimers very slowly, although it is as uv-resistant as its mfd + B/r parent strain. We have found that the mfd mutant performs the initial incision step of excision repair normally, but repairs the resulting single-strand breaks much more slowly than the mfd + strain. In spite of the slow dimer excision in the mfd mutant, single-strand DNA breaks do not accumulate during postirradiation incubation, implying that incision and excision are well corrdinated. the prolonged postirradiation lag in cell division and DNA synthesis which accompany slow excision in the mfd strain indicates that resumption of these processes of optimal rates is linked to the timing of excision repair. The normal uv-resistance of the mfd mutant also suggests such coordination and shows that the rate of excision repair is independent of its ultimate efficiency in the removal of potentially lethal uv-induced damage. (U.S.)

Germline mutations in lysine specific demethylase 1 (LSD1/KDM1A) confer susceptibility to multiple myeloma.

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Wei, Xiaomu; Calvo-Vidal, M Nieves; Chen, Siwei; Wu, Gang; Revuelta, Maria V; Sun, Jian; Zhang, Jinghui; Walsh, Michael F; Nichols, Kim E; Joseph, Vijai; Snyder, Carrie; Vachon, Celine M; McKay, James D; Wang, Shu-Ping; Jayabalan, David S; Jacobs, Lauren M; Becirovic, Dina; Waller, Rosalie G; Artomov, Mykyta; Viale, Agnes; Patel, Jayeshkumar; Phillip, Jude M; Chen-Kiang, Selina; Curtin, Karen; Salama, Mohamed; Atanackovic, Djordje; Niesvizky, Ruben; Landgren, Ola; Slager, Susan L; Godley, Lucy A; Churpek, Jane; Garber, Judy E; Anderson, Kenneth C; Daly, Mark J; Roeder, Robert G; Dumontet, Charles; Lynch, Henry T; Mullighan, Charles G; Camp, Nicola J; Offit, Kenneth; Klein, Robert J; Yu, Haiyuan; Cerchietti, Leandro; Lipkin, Steven M

2018-03-20

Given the frequent and largely incurable occurrence of multiple myeloma (MM), identification of germline genetic mutations that predispose cells to MM may provide insight into disease etiology and the developmental mechanisms of its cell of origin, the plasma cell. Here we identified familial and early-onset MM kindreds with truncating mutations in lysine-specific demethylase 1 (LSD1/KDM1A), an epigenetic transcriptional repressor that primarily demethylates histone H3 on lysine 4 and regulates hematopoietic stem cell self-renewal. Additionally, we found higher rates of germline truncating and predicted deleterious missense KDM1A mutations in MM patients unselected for family history compared to controls. Both monoclonal gammopathy of unknown significance (MGUS) and MM cells have significantly lower KDM1A transcript levels compared with normal plasma cells. Transcriptome analysis of MM cells from KDM1A mutation carriers shows enrichment of pathways and MYC target genes previously associated with myeloma pathogenesis. In mice, antigen challenge followed by pharmacological inhibition of KDM1A promoted plasma cell expansion, enhanced secondary immune response, elicited appearance of serum paraprotein, and mediated upregulation of MYC transcriptional targets. These changes are consistent with the development of MGUS. Collectively, our findings show KDM1A is the first autosomal dominant MM germline predisposition gene, providing new insights into its mechanistic roles as a tumor suppressor during post-germinal center B cell differentiation. Copyright ©2018, American Association for Cancer Research.

Mutant p53 drives cancer by subverting multiple tumour suppression pathways

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Sue eHaupt

2016-01-01

Full Text Available The tumour suppressor p53 normally acts as a brake to halt damaged cells from perpetrating their genetic errors into future generations. If p53 is disrupted by mutation, it may not only lose these corrective powers, but counter-productively acquire new capacities that drive cancer. A newly emerging manner in which mutant p53 executes its cancer promoting functions is by harnessing key proteins (including many transcription factors, which normally partner with its wild type, tumour-inhibiting counterpart. In association with the subverted activities of these protein partners, mutant p53 is empowered to act across multiple fundamental cellular pathways (regulating cell division and metabolism and corrupt them to become cancer promoting.

Molecular mechanisms of carcinogenesis

International Nuclear Information System (INIS)

Hall, E.J.

1997-01-01

The possibility that chromosomal changes are responsible for neoplasia was proposed in the early years of this century. A combination of improved cytogenetics and the advent of recombinant technology has settled the issue. As recently as 20 years ago, however, the genetic and molecular basis of familiar predisposition to cancer were a mystery, and it is only in the last few years that light has been shed on a few specific types of malignancies. As the genetic basis of human cancer had been documented, a number of genes have been identified as functioning either as oncogenes which act in a dominant fashion to promote tumor growth when mutated, or as tumor suppressor genes which act in a recessive fashion

Influence of the MDM2 single nucleotide polymorphism SNP309 on tumour development in BRCA1 mutation carriers

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Johnson Peter W

2006-03-01

Full Text Available Abstract Background The MDM2 gene encodes a negative regulator of the p53 tumour suppressor protein. A single nucleotide polymorphism (SNP in the MDM2 promoter (a T to G exchange at nucleotide 309 has been reported to produce accelerated tumour formation in individuals with inherited p53 mutations. We have investigated the effect of the MDM2 SNP309 on clinical outcome in a cohort of patients with germline mutations of BRCA1. Methods Genomic DNA was obtained for 102 healthy controls and 116 patients with established pathogenic mutations of BRCA1 and Pyrosequencing technology™ was used to determine the genotype at the MDM2 SNP309 locus. Results The polymorphism was present in 52.9% of the controls (G/T in 37.3% and G/G in 15.6% and 58.6% of the BRCA1 mutation carriers (47.4% G/T and 11.2% G/G. Incidence of malignancy in female BRCA1 carriers was not significantly higher in SNP309 carriers than in wildtype (T/T individuals (72.7% vs. 75.6%, p = 1.00. Mean age of diagnosis of first breast cancer was 41.2 years in the SNP309 G/G genotype carriers, 38.6 years in those with the SNP309 G/T genotype and 39.0 years in wildtype subjects (p = 0.80. Conclusion We found no evidence that the MDM2 SNP309 accelerates tumour development in carriers of known pathogenic germline mutations of BRCA1.

Aging, tumor suppression and cancer: High-wire act!

Energy Technology Data Exchange (ETDEWEB)

Campisi, Judith

2004-08-15

Evolutionary theory holds that aging is a consequence of the declining force of natural selection with age. We discuss here the evidence that among the causes of aging in complex multicellular organisms, such as mammals, is the antagonistically pleiotropic effects of the cellular responses that protect the organism from cancer. Cancer is relatively rare in young mammals, owing in large measure to the activity of tumor suppressor mechanisms. These mechanisms either protect the genome from damage and/or mutations, or they elicit cellular responses--apoptosis or senescence--that eliminate or prevent the proliferation of somatic cells at risk for neoplastic transformation.We focus here on the senescence response, reviewing its causes, regulation and effects. In addition, we describe recent data that support the idea that both senescence and apoptosis may indeed be the double-edged swords predicted by the evolutionary hypothesis of antagonistic pleiotropy--protecting organisms from cancer early in life, but promoting aging phenotypes, including late life cancer, in older organisms.

A Novel Mutation in Isoform 3 of the Plasma Membrane Ca2+ Pump Impairs Cellular Ca2+ Homeostasis in a Patient with Cerebellar Ataxia and Laminin Subunit 1α Mutations.

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Calì, Tito; Lopreiato, Raffaele; Shimony, Joshua; Vineyard, Marisa; Frizzarin, Martina; Zanni, Ginevra; Zanotti, Giuseppe; Brini, Marisa; Shinawi, Marwan; Carafoli, Ernesto

2015-06-26

The particular importance of Ca(2+) signaling to neurons demands its precise regulation within their cytoplasm. Isoform 3 of the plasma membrane Ca(2+) ATPase (the PMCA3 pump), which is highly expressed in brain and cerebellum, plays an important role in the regulation of neuronal Ca(2+). A genetic defect of the PMCA3 pump has been described in one family with X-linked congenital cerebellar ataxia. Here we describe a novel mutation in the ATP2B3 gene in a patient with global developmental delay, generalized hypotonia and cerebellar ataxia. The mutation (a R482H replacement) impairs the Ca(2+) ejection function of the pump. It reduces the ability of the pump expressed in model cells to control Ca(2+) transients generated by cell stimulation and impairs its Ca(2+) extrusion function under conditions of low resting cytosolic Ca(2+) as well. In silico analysis of the structural effect of the mutation suggests a reduced stabilization of the portion of the pump surrounding the mutated residue in the Ca(2+)-bound state. The patient also carries two missense mutations in LAMA1, encoding laminin subunit 1α. On the basis of the family pedigree of the patient, the presence of both PMCA3 and laminin subunit 1α mutations appears to be necessary for the development of the disease. Considering the observed defect in cellular Ca(2+) homeostasis and the previous finding that PMCAs act as digenic modulators in Ca(2+)-linked pathologies, the PMCA3 dysfunction along with LAMA1 mutations could act synergistically to cause the neurological phenotype. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

A Novel Mutation in Isoform 3 of the Plasma Membrane Ca2+ Pump Impairs Cellular Ca2+ Homeostasis in a Patient with Cerebellar Ataxia and Laminin Subunit 1α Mutations*

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Calì, Tito; Lopreiato, Raffaele; Shimony, Joshua; Vineyard, Marisa; Frizzarin, Martina; Zanni, Ginevra; Zanotti, Giuseppe; Brini, Marisa; Shinawi, Marwan; Carafoli, Ernesto

2015-01-01

The particular importance of Ca2+ signaling to neurons demands its precise regulation within their cytoplasm. Isoform 3 of the plasma membrane Ca2+ ATPase (the PMCA3 pump), which is highly expressed in brain and cerebellum, plays an important role in the regulation of neuronal Ca2+. A genetic defect of the PMCA3 pump has been described in one family with X-linked congenital cerebellar ataxia. Here we describe a novel mutation in the ATP2B3 gene in a patient with global developmental delay, generalized hypotonia and cerebellar ataxia. The mutation (a R482H replacement) impairs the Ca2+ ejection function of the pump. It reduces the ability of the pump expressed in model cells to control Ca2+ transients generated by cell stimulation and impairs its Ca2+ extrusion function under conditions of low resting cytosolic Ca2+ as well. In silico analysis of the structural effect of the mutation suggests a reduced stabilization of the portion of the pump surrounding the mutated residue in the Ca2+-bound state. The patient also carries two missense mutations in LAMA1, encoding laminin subunit 1α. On the basis of the family pedigree of the patient, the presence of both PMCA3 and laminin subunit 1α mutations appears to be necessary for the development of the disease. Considering the observed defect in cellular Ca2+ homeostasis and the previous finding that PMCAs act as digenic modulators in Ca2+-linked pathologies, the PMCA3 dysfunction along with LAMA1 mutations could act synergistically to cause the neurological phenotype. PMID:25953895

Compactness of viral genomes: effect of disperse and localized random mutations

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Lošdorfer Božič, Anže; Micheletti, Cristian; Podgornik, Rudolf; Tubiana, Luca

2018-02-01

Genomes of single-stranded RNA viruses have evolved to optimize several concurrent properties. One of them is the architecture of their genomic folds, which must not only feature precise structural elements at specific positions, but also allow for overall spatial compactness. The latter was shown to be disrupted by random synonymous mutations, a disruption which can consequently negatively affect genome encapsidation. In this study, we use three mutation schemes with different degrees of locality to mutate the genomes of phage MS2 and Brome Mosaic virus in order to understand the observed sensitivity of the global compactness of their folds. We find that mutating local stretches of their genomes’ sequence or structure is less disruptive to their compactness compared to inducing randomly-distributed mutations. Our findings are indicative of a mechanism for the conservation of compactness acting on a global scale of the genomes, and have several implications for understanding the interplay between local and global architecture of viral RNA genomes.

Expression of the tumor suppressor genes NF2, 4.1B, and TSLC1 in canine meningiomas.

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Dickinson, P J; Surace, E I; Cambell, M; Higgins, R J; Leutenegger, C M; Bollen, A W; LeCouteur, R A; Gutmann, D H

2009-09-01

Meningiomas are common primary brain tumors in dogs; however, little is known about the molecular genetic mechanisms involved in their tumorigenesis. Several tumor suppressor genes have been implicated in meningioma pathogenesis in humans, including the neurofibromatosis 2 (NF2), protein 4.1B (4.1 B), and tumor suppressor in lung cancer-1 (TSLC1) genes. We investigated the expression of these tumor suppressor genes in a series of spontaneous canine meningiomas using quantitative real-time reverse transcription polymerase chain reaction (RT-PCR) (NF2; n = 25) and western blotting (NF2/merlin, 4.1B, TSLC1; n = 30). Decreased expression of 4.1B and TSLC1 expression on western blotting was seen in 6/30 (20%) and in 15/30 (50%) tumors, respectively, with 18/30 (60%) of meningiomas having decreased or absent expression of one or both proteins. NF2 gene expression assessed by western blotting and RT-PCR varied considerably between individual tumors. Complete loss of NF2 protein on western blotting was not seen, unlike 4.1B and TSLC1. Incidence of TSLC1 abnormalities was similar to that seen in human meningiomas, while perturbation of NF2 and 4.1B appeared to be less common than reported for human tumors. No association was observed between tumor grade, subtype, or location and tumor suppressor gene expression based on western blot or RT-PCR. These results suggest that loss of these tumor suppressor genes is a frequent occurrence in canine meningiomas and may be an early event in tumorigenesis in some cases. In addition, it is likely that other, as yet unidentified, genes play an important role in canine meningioma formation and growth.

An alternative derivation of the stationary distribution of the multivariate neutral Wright-Fisher model for low mutation rates with a view to mutation rate estimation from site frequency data.

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Schrempf, Dominik; Hobolth, Asger

2017-04-01

Recently, Burden and Tang (2016) provided an analytical expression for the stationary distribution of the multivariate neutral Wright-Fisher model with low mutation rates. In this paper we present a simple, alternative derivation that illustrates the approximation. Our proof is based on the discrete multivariate boundary mutation model which has three key ingredients. First, the decoupled Moran model is used to describe genetic drift. Second, low mutation rates are assumed by limiting mutations to monomorphic states. Third, the mutation rate matrix is separated into a time-reversible part and a flux part, as suggested by Burden and Tang (2016). An application of our result to data from several great apes reveals that the assumption of stationarity may be inadequate or that other evolutionary forces like selection or biased gene conversion are acting. Furthermore we find that the model with a reversible mutation rate matrix provides a reasonably good fit to the data compared to the one with a non-reversible mutation rate matrix. Copyright © 2016 The Author(s). Published by Elsevier Inc. All rights reserved.

Germline PMS2 and somatic POLE exonuclease mutations cause hypermutability of the leading DNA strand in biallelic mismatch repair deficiency syndrome brain tumours.

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Andrianova, Maria A; Chetan, Ghati Kasturirangan; Sibin, Madathan Kandi; Mckee, Thomas; Merkler, Doron; Narasinga, Rao Kvl; Ribaux, Pascale; Blouin, Jean-Louis; Makrythanasis, Periklis; Seplyarskiy, Vladimir B; Antonarakis, Stylianos E; Nikolaev, Sergey I

2017-11-01

Biallelic mismatch repair deficiency (bMMRD) in tumours is frequently associated with somatic mutations in the exonuclease domains of DNA polymerases POLE or POLD1, and results in a characteristic mutational profile. In this article, we describe the genetic basis of ultramutated high-grade brain tumours in the context of bMMRD. We performed exome sequencing of two second-cousin patients from a large consanguineous family of Indian origin with early onset of high-grade glioblastoma and astrocytoma. We identified a germline homozygous nonsense variant, p.R802*, in the PMS2 gene. Additionally, by genome sequencing of these tumours, we found extremely high somatic mutation rates (237/Mb and 123/Mb), as well as somatic mutations in the proofreading domain of POLE polymerase (p.P436H and p.L424V), which replicates the leading DNA strand. Most interestingly, we found, in both cancers, that the vast majority of mutations were consistent with the signature of POLE exo - , i.e. an abundance of C>A and C>T mutations, particularly in special contexts, on the leading strand. We showed that the fraction of mutations under positive selection among mutations in tumour suppressor genes is more than two-fold lower in ultramutated tumours than in other glioblastomas. Genetic analyses enabled the diagnosis of the two consanguineous childhood brain tumours as being due to a combination of PMS2 germline and POLE somatic variants, and confirmed them as bMMRD/POLE exo - disorders. Copyright © 2017 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd. Copyright © 2017 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Constitutional FLCN mutations in patients with suspected Birt-Hogg-Dubé syndrome ascertained for non-cutaneous manifestations.

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Maffé, A; Toschi, B; Circo, G; Giachino, D; Giglio, S; Rizzo, A; Carloni, A; Poletti, V; Tomassetti, S; Ginardi, C; Ungari, S; Genuardi, M

2011-04-01

Birt-Hogg-Dubé syndrome (BHDS) is characterized by a clinical triad including cutaneous hamartomas originating from hair follicles, lung cysts/pneumothorax, and kidney tumors. Inactivating mutations of the tumor suppressor gene FLCN are identified in most families with BHDS. Usually, patients are referred for genetic examination by dermatologists because of the presence of typical multiple skin tumors with or without additional symptoms. However, because of phenotypic variability and incomplete penetrance, the clinical presentation of BHDS is not yet fully defined. Criteria for genetic testing and diagnosis that take into account variable manifestations have recently been proposed by the European BHD Consortium. We sequenced the FLCN gene coding region in a series of 19 patients selected for kidney and/or lung manifestations. Overall, FLCN mutations were found in 9 of 19 (47%) families and were detected only in probands who had either >2 components of the clinical triad or a single component (renal or pulmonary) along with a family history of another main BHDS manifestation. Typical cutaneous lesions were present only in 8 of 21 FLCN mutation carriers aged >20 years identified in the mutation-positive families. In addition, we provide clinical and molecular evidence that parotid oncocytoma, so far reported in six BHDS cases, is associated with this condition, based on the observation of a patient with bilateral parotid involvement and marked reduction of the wild-type FLCN allele signal in tumor DNA. Overall, the results obtained in this study contribute to the definition of the phenotypic characteristics that should be considered for BHDS diagnosis and FLCN mutation testing. © 2010 John Wiley & Sons A/S.

Murine neonatal spleen contains natural T and non-T suppressor cells capable of inhibiting adult alloreactive and newborn autoreactive T-cell proliferation.

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Hooper, D C; Hoskin, D W; Gronvik, K O; Murgita, R A

1986-05-01

The spleen of neonatal mice is known to be a rich source of cells capable of suppressing a variety of immune functions of adult lymphocytes in vitro. From such observations has emerged the concept that the gradual development in ability to express immune functions after birth is due in part to the parallel normal physiological decay of naturally occurring regulatory suppressor cells. There is, however, some confusion in the literature as to the exact nature of the newborn of the newborn inhibitory cell type(s). In contrast to most previous reports which detect only a single type of neonatal suppressor cell, usually a T cell, we show here that newborn spleen harbors both T and non-T inhibitory cells. Both types of suppressor cells could be shown to suppress the proliferative response of adult spleen to alloantigens as well as newborn T cells reacting against self-Ia antigen in the autologous mixed lymphocyte reaction (AMLR). Newborn suppressor T cells were characterized as being non-adherent to Ig-anti-Ig affinity columns, soybean agglutinin receptor negative (SBA-), and susceptible to lysis by anti-T-cell specific antiserum plus complement. Non-T suppressor cells were identified as non-phagocytic, SBA receptor positive (SBA+), and resistant to cytotoxic treatment with anti-T-cell antibodies and complement. The apparent controversy surrounding previous reports as to the T versus non-T nature of newborn suppressor cells can be reconciled by the present observation that both types of inhibitory cells coexist in the spleen. Furthermore, the demonstration that newborn suppressor cells can effectively regulate T-cell proliferative activity mediated by other newborn cells provides more direct support for the contention that such inhibitory cells play a physiological role in controlling immune responsiveness during early ontogeny.

Introduction of in vitro transcribed ENO1 mRNA into neuroblastoma cells induces cell death

International Nuclear Information System (INIS)

Ejeskär, Katarina; Krona, Cecilia; Carén, Helena; Zaibak, Faten; Li, Lingli; Martinsson, Tommy; Ioannou, Panayiotis A

2005-01-01

Neuroblastoma is a solid tumour of childhood often with an unfavourable outcome. One common genetic feature in aggressive tumours is 1p-deletion. The α-enolase (ENO1) gene is located in chromosome region 1p36.2, within the common region of deletion in neuroblastoma. One alternative translated product of the ENO1 gene, known as MBP-1, acts as a negative regulator of the c-myc oncogene, making the ENO1 gene a candidate as a tumour suppressor gene. Methods used in this study are transfection of cDNA-vectors and in vitro transcribed mRNA, cell growth assay, TUNEL-assay, real-time RT-PCR (TaqMan) for expression studies, genomic sequencing and DHPLC for mutation detection. Here we demonstrate that transfection of ENO1 cDNA into 1p-deleted neuroblastoma cell lines causes' reduced number of viable cells over time compared to a negative control and that it induces apoptosis. Interestingly, a similar but much stronger dose-dependent reduction of cell growth was observed by transfection of in vitro transcribed ENO1 mRNA into neuroblastoma cells. These effects could also be shown in non-neuroblastoma cells (293-cells), indicating ENO1 to have general tumour suppressor activity. Expression of ENO1 is detectable in primary neuroblastomas of all different stages and no difference in the level of expression can be detected between 1p-deleted and 1p-intact tumour samples. Although small numbers (11 primary neuroblastomas), there is some evidence that Stage 4 tumours has a lower level of ENO1-mRNA than Stage 2 tumours (p = 0.01). However, mutation screening of 44 primary neuroblastomas of all different stages, failed to detect any mutations. Our studies indicate that ENO1 has tumour suppressor activity and that high level of ENO1 expression has growth inhibitory effects

Natural killer activity and suppressor cells in irradiated mice repopulated with a mixture of cells from normal and 89Sr-treated donors

International Nuclear Information System (INIS)

Levy, E.M.; Kumar, V.; Bennett, M.

1981-01-01

Mice that have been injected with 89 Sr have fairly normal B and T cell function, but are abnormal in that they lack natural killer (NK) activity and other functions that require an intact bone marrow. These mice also have an increased potential for suppressor cell activity. We had previously shown that spleen cells from 89 Sr-treated mice could transfer low NK activity and increased suppressor cell function to lethally irradiated syngeneic recipients. To investigate the mechanisms involved in perpetuating these defects, groups of normal spleen or bone marrow cells. Recipients were assayed for their NK activity and suppressor cell function 5 to 14 wk later. it was found that the addition of normal cells in the donor inoculum resulted in normal NK activity. This indicates that low NK activity in 89 Sr-treated mice was not due to the presence of a suppressor cell that prevented NK cell generation. It was additionally found that low NK activity in recipient mice could be boosted by interferon inducers. This would indicate that NK activity in the recipients was not due to a lack of interferon-sensitive pre-NK cells. Suppressor cell function in recipient mice depended on the type and number of normal cells in the donor inoculum. Bone marrow cells were very efficient in overcoming the tendency to produce suppressor cells. It took approximately 20 times more normal spleen cells to produce the same results. The implications of these findings are discussed

Enhanced vulnerability of human proteins towards disease-associated inactivation through divergent evolution.

Science.gov (United States)

Medina-Carmona, Encarnación; Fuchs, Julian E; Gavira, Jose A; Mesa-Torres, Noel; Neira, Jose L; Salido, Eduardo; Palomino-Morales, Rogelio; Burgos, Miguel; Timson, David J; Pey, Angel L

2017-09-15

Human proteins are vulnerable towards disease-associated single amino acid replacements affecting protein stability and function. Interestingly, a few studies have shown that consensus amino acids from mammals or vertebrates can enhance protein stability when incorporated into human proteins. Here, we investigate yet unexplored relationships between the high vulnerability of human proteins towards disease-associated inactivation and recent evolutionary site-specific divergence of stabilizing amino acids. Using phylogenetic, structural and experimental analyses, we show that divergence from the consensus amino acids at several sites during mammalian evolution has caused local protein destabilization in two human proteins linked to disease: cancer-associated NQO1 and alanine:glyoxylate aminotransferase, mutated in primary hyperoxaluria type I. We demonstrate that a single consensus mutation (H80R) acts as a disease suppressor on the most common cancer-associated polymorphism in NQO1 (P187S). The H80R mutation reactivates P187S by enhancing FAD binding affinity through local and dynamic stabilization of its binding site. Furthermore, we show how a second suppressor mutation (E247Q) cooperates with H80R in protecting the P187S polymorphism towards inactivation through long-range allosteric communication within the structural ensemble of the protein. Our results support that recent divergence of consensus amino acids may have occurred with neutral effects on many functional and regulatory traits of wild-type human proteins. However, divergence at certain sites may have increased the propensity of some human proteins towards inactivation due to disease-associated mutations and polymorphisms. Consensus mutations also emerge as a potential strategy to identify structural hot-spots in proteins as targets for pharmacological rescue in loss-of-function genetic diseases. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please

Downregulation but lack of promoter hypermethylation or somatic mutations of the potential tumor suppressor CXXC5 in MDS and AML with deletion 5q

DEFF Research Database (Denmark)

Treppendahl, Marianne Bach; Möllgård, L; Hellström-Lindberg, E

2013-01-01

During recent years mutations in epigenetic modulators have been identified in several human cancers, including acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS)[1]. CXXC5 has been found to be necessary for retinoic acid induced differentiation of myelocytic leukemia cells, identify......During recent years mutations in epigenetic modulators have been identified in several human cancers, including acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS)[1]. CXXC5 has been found to be necessary for retinoic acid induced differentiation of myelocytic leukemia cells...

Genetic and biochemical evidence that haploinsufficiency of the Nf1 tumor suppressor gene modulates melanocyte and mast cell fates in vivo.

Science.gov (United States)

Ingram, D A; Yang, F C; Travers, J B; Wenning, M J; Hiatt, K; New, S; Hood, A; Shannon, K; Williams, D A; Clapp, D W

2000-01-03

Neurofibromatosis type 1 (NF1) is a common autosomal-dominant disorder characterized by cutaneous neurofibromas infiltrated with large numbers of mast cells, melanocyte hyperplasia, and a predisposition to develop malignant neoplasms. NF1 encodes a GTPase activating protein (GAP) for Ras. Consistent with Knudson's "two hit" model of tumor suppressor genes, leukemias and malignant solid tumors in NF1 patients frequently demonstrate somatic loss of the normal NF1 allele. However, the phenotypic and biochemical consequences of heterozygous inactivation of Nf1 are largely unknown. Recently neurofibromin, the protein encoded by NF1, was shown to negatively regulate Ras activity in Nf1-/- murine myeloid hematopoietic cells in vitro through the c-kit receptor tyrosine kinase (dominant white spotting, W). Since the W and Nf1 locus appear to function along a common developmental pathway, we generated mice with mutations at both loci to examine potential interactions in vivo. Here, we show that haploinsufficiency at Nf1 perturbs cell fates in mast cells in vivo, and partially rescues coat color and mast cell defects in W(41) mice. Haploinsufficiency at Nf1 also increased mast cell proliferation, survival, and colony formation in response to Steel factor, the ligand for c-kit. Furthermore, haploinsufficiency was associated with enhanced Ras-mitogen-activated protein kinase activity, a major downstream effector of Ras, via wild-type and mutant (W(41)) c-kit receptors. These observations identify a novel interaction between c-kit and neurofibromin in vivo, and offer experimental evidence that haploinsufficiency of Nf1 alters both cellular and biochemical phenotypes in two cell lineages that are affected in individuals with NF1. Collectively, these data support the emerging concept that heterozygous inactivation of tumor suppressor genes may have profound biological effects in multiple cell types.

Evidence that WT1 mutations in Denys-Drash syndrome patients may act in a dominant-negative fashion

NARCIS (Netherlands)

Little, M. H.; Williamson, K. A.; Mannens, M.; Kelsey, A.; Gosden, C.; Hastie, N. D.; van Heyningen, V.

1993-01-01

The triad of nephropathy, partial gonadal dysgenesis and Wilms' tumour (WT) is known as Denys-Drash syndrome (DDS). The WT predisposition gene WT1, which plays a vital role in both genital and renal development, is known to be mutated in DDS patients. The WT1 mutations in these patients are

Novel somatic and germline mutations in intracranial germ cell tumours.

Science.gov (United States)

Wang, Linghua; Yamaguchi, Shigeru; Burstein, Matthew D; Terashima, Keita; Chang, Kyle; Ng, Ho-Keung; Nakamura, Hideo; He, Zongxiao; Doddapaneni, Harshavardhan; Lewis, Lora; Wang, Mark; Suzuki, Tomonari; Nishikawa, Ryo; Natsume, Atsushi; Terasaka, Shunsuke; Dauser, Robert; Whitehead, William; Adekunle, Adesina; Sun, Jiayi; Qiao, Yi; Marth, Gábor; Muzny, Donna M; Gibbs, Richard A; Leal, Suzanne M; Wheeler, David A; Lau, Ching C

2014-07-10

Intracranial germ cell tumours (IGCTs) are a group of rare heterogeneous brain tumours that are clinically and histologically similar to the more common gonadal GCTs. IGCTs show great variation in their geographical and gender distribution, histological composition and treatment outcomes. The incidence of IGCTs is historically five- to eightfold greater in Japan and other East Asian countries than in Western countries, with peak incidence near the time of puberty. About half of the tumours are located in the pineal region. The male-to-female incidence ratio is approximately 3-4:1 overall, but is even higher for tumours located in the pineal region. Owing to the scarcity of tumour specimens available for research, little is currently known about this rare disease. Here we report the analysis of 62 cases by next-generation sequencing, single nucleotide polymorphism array and expression array. We find the KIT/RAS signalling pathway frequently mutated in more than 50% of IGCTs, including novel recurrent somatic mutations in KIT, its downstream mediators KRAS and NRAS, and its negative regulator CBL. Novel somatic alterations in the AKT/mTOR pathway included copy number gains of the AKT1 locus at 14q32.33 in 19% of patients, with corresponding upregulation of AKT1 expression. We identified loss-of-function mutations in BCORL1, a transcriptional co-repressor and tumour suppressor. We report significant enrichment of novel and rare germline variants in JMJD1C, which codes for a histone demethylase and is a coactivator of the androgen receptor, among Japanese IGCT patients. This study establishes a molecular foundation for understanding the biology of IGCTs and suggests potentially promising therapeutic strategies focusing on the inhibition of KIT/RAS activation and the AKT1/mTOR pathway.

Novel somatic and germline mutations in intracranial germ cell tumors

Science.gov (United States)

Wang, Linghua; Yamaguchi, Shigeru; Burstein, Matthew D.; Terashima, Keita; Chang, Kyle; Ng, Ho-Keung; Nakamura, Hideo; He, Zongxiao; Doddapaneni, Harshavardhan; Lewis, Lora; Wang, Mark; Suzuki, Tomonari; Nishikawa, Ryo; Natsume, Atsushi; Terasaka, Shunsuke; Dauser, Robert; Whitehead, William; Adekunle, Adesina; Sun, Jiayi; Qiao, Yi; Marth, Gábor; Muzny, Donna M.; Gibbs, Richard A.; Leal, Suzanne M.; Wheeler, David A.; Lau, Ching C.

2015-01-01

Intracranial germ cell tumors (IGCTs) are a group of rare heterogeneous brain tumors which are clinically and histologically similar to the more common gonadal GCTs. IGCTs show great variation in their geographic and gender distribution, histological composition and treatment outcomes. The incidence of IGCTs is historically 5–8 fold greater in Japan and other East Asian countries than in Western countries1 with peak incidence near the time of puberty2. About half of the tumors are located in the pineal region. The male-to-female incidence ratio is approximately 3–4:1 overall but even higher for tumors located in the pineal region3. Due to the scarcity of tumor specimens available for research, little is currently known about this rare disease. Here we report the analysis of 62 cases by next generation sequencing, SNP array and expression array. We find the KIT/RAS signaling pathway frequently mutated in over 50% of IGCTs including novel recurrent somatic mutations in KIT, its downstream mediators KRAS and NRAS, and its negative regulator CBL. Novel somatic alterations in the AKT/mTOR pathway included copy number gain of the AKT1 locus at 14q32.33 in 19% of patients, with corresponding upregulation of AKT1 expression. We identified loss-of-function mutations in BCORL1, a transcriptional corepressor and tumor suppressor. We report significant enrichment of novel and rare germline variants in JMJD1C, a histone demethylase and coactivator of the androgen receptor, among Japanese IGCT patients. This study establishes a molecular foundation for understanding the biology of IGCTs and suggests potentially promising therapeutic strategies focusing on the inhibition of KIT/RAS activation and the AKT1/mTOR pathway. PMID:24896186

ZNF649, a novel Kruppel type zinc-finger protein, functions as a transcriptional suppressor

International Nuclear Information System (INIS)

Yang Hong; Yuan Wuzhou; Wang Ying; Zhu Chuanbing; Liu Bisheng; Wang Yuequn; Yang, Dan; Li Yongqing; Wang Canding; Wu Xiushan; Liu Mingyao

2005-01-01

Cardiac differentiation involves a cascade of coordinated gene expression that regulates cell proliferation and matrix protein formation in a defined temporo-spatial manner. Many of the KRAB-ZFPs are involved in cardiac development or cardiovascular diseases. Here we report the identification and characterization of a novel human zinc-finger gene named ZNF649. The cDNA of ZNF649 is 3176 bp, encoding a protein of 505 amino acids in the nuclei. Northern blot analysis indicates that ZNF649 is expressed in most of the examined human adult and embryonic tissues. ZNF649 is a transcription suppressor when fused to GAL-4 DNA-binding domain and cotransfected with VP-16. Overexpression of ZNF649 in COS-7 cells inhibits the transcriptional activities of SRE and AP-1. Deletion analysis with a series of truncated fusion proteins indicates that the KRAB motif is a basal repression domain when the truncated fusion proteins were assayed for the transcriptional activities of SRE and AP-1. These results suggest that ZNF649 protein may act as a transcriptional repressor in mitogen-activated protein kinase signaling pathway to mediate cellular functions

Human germline hedgehog pathway mutations predispose to fatty liver.

Science.gov (United States)

Guillen-Sacoto, Maria J; Martinez, Ariel F; Abe, Yu; Kruszka, Paul; Weiss, Karin; Everson, Joshua L; Bataller, Ramon; Kleiner, David E; Ward, Jerrold M; Sulik, Kathleen K; Lipinski, Robert J; Solomon, Benjamin D; Muenke, Maximilian

2017-10-01

Non-alcoholic fatty liver disease (NAFLD) is the most common form of liver disease. Activation of hedgehog (Hh) signaling has been implicated in the progression of NAFLD and proposed as a therapeutic target; however, the effects of Hh signaling inhibition have not been studied in humans with germline mutations that affect this pathway. Patients with holoprosencephaly (HPE), a disorder associated with germline mutations disrupting Sonic hedgehog (SHH) signaling, were clinically evaluated for NAFLD. A combined mouse model of Hh signaling attenuation (Gli2 heterozygous null: Gli2 +/- ) and diet-induced NAFLD was used to examine aspects of NAFLD and hepatic gene expression profiles, including molecular markers of hepatic fibrosis and inflammation. Patients with HPE had a higher prevalence of liver steatosis compared to the general population, independent of obesity. Exposure of Gli2 +/- mice to fatty liver-inducing diets resulted in increased liver steatosis compared to wild-type mice. Similar to humans, this effect was independent of obesity in the mutant mice and was associated with decreased expression of pro-fibrotic and pro-inflammatory genes, and increased expression of PPARγ, a potent anti-fibrogenic and anti-inflammatory regulator. Interestingly, tumor suppressors p53 and p16INK4 were found to be downregulated in the Gli2 +/- mice exposed to a high-fat diet. Our results indicate that germline mutations disrupting Hh signaling promotes liver steatosis, independent of obesity, with reduced fibrosis. While Hh signaling inhibition has been associated with a better NAFLD prognosis, further studies are required to evaluate the long-term effects of mutations affecting this pathway. Lay summary: Non-alcoholic fatty liver disease (NAFLD) is characterized by excess fat deposition in the liver predominantly due to high calorie intake and a sedentary lifestyle. NAFLD progression is usually accompanied by activation of the Sonic hedgehog (SHH) pathway leading to fibrous

Pro-106-Ser mutation and EPSPS overexpression acting together simultaneously in glyphosate-resistant goosegrass (Eleusine indica).

Science.gov (United States)

Gherekhloo, Javid; Fernández-Moreno, Pablo T; Alcántara-de la Cruz, Ricardo; Sánchez-González, Eduardo; Cruz-Hipolito, Hugo E; Domínguez-Valenzuela, José A; De Prado, Rafael

2017-07-27

Glyphosate has been used for more than 15 years for weed management in citrus groves in the Gulf of Mexico, at up to 3-4 applications per year. Goosegrass (Eleusine indica (L.) Gaertn.) control has sometimes failed. In this research, the mechanisms governing three goosegrass biotypes (Ein-Or from an orange grove, and Ein-Pl1 and Ein-Pl2 from Persian lime groves) with suspected resistance to glyphosate were characterized and compared to a susceptible biotype (Ein-S). Dose-response and shikimate accumulation assays confirmed resistance of the resistant (R) biotypes. There were no differences in glyphosate absorption, but the R biotypes retained up to 62-78% of the herbicide in the treated leaf at 96 h after treatment (HAT), in comparison to the Ein-S biotype (36%). The 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS) activity in the Ein-Or and Ein-S biotypes was over 100-fold lower than the Ein-Pl1 and Ein-Pl2 ones. The latter showed a high EPSPS-basal activity, a mutation at Pro-106-Ser position in the EPSPS gene, and EPSPS overexpression. The EPSPS basal and EPSPS overexpression were positively correlated. The R goosegrass biotypes displayed poor glyphosate translocation. Furthermore, this grassweed showed, for the first time, two mechanisms at the target-site level (Pro-106-Ser mutation + EPSPS overexpression) acting together simultaneously against glyphosate.

Inhibition of colorectal cancer genomic copy number alterations and chromosomal fragile site tumor suppressor FHIT and WWOX deletions by DNA mismatch repair

Science.gov (United States)

Gelincik, Ozkan; Blecua, Pedro; Edelmann, Winfried; Kucherlapati, Raju; Zhou, Kathy; Jasin, Maria; Gümüş, Zeynep H.; Lipkin, Steven M.

2017-01-01

Homologous recombination (HR) enables precise DNA repair after DNA double strand breaks (DSBs) using identical sequence templates, whereas homeologous recombination (HeR) uses only partially homologous sequences. Homeologous recombination introduces mutations through gene conversion and genomic deletions through single-strand annealing (SSA). DNA mismatch repair (MMR) inhibits HeR, but the roles of mammalian MMR MutL homologues (MLH1, PMS2 and MLH3) proteins in HeR suppression are poorly characterized. Here, we demonstrate that mouse embryonic fibroblasts (MEFs) carrying Mlh1, Pms2, and Mlh3 mutations have higher HeR rates, by using 7,863 uniquely mapping paired direct repeat sequences (DRs) in the mouse genome as endogenous gene conversion and SSA reporters. Additionally, when DSBs are induced by gamma-radiation, Mlh1, Pms2 and Mlh3 mutant MEFs have higher DR copy number alterations (CNAs), including DR CNA hotspots previously identified in mouse MMR-deficient colorectal cancer (dMMR CRC). Analysis of The Cancer Genome Atlas CRC data revealed that dMMR CRCs have higher genome-wide DR HeR rates than MMR proficient CRCs, and that dMMR CRCs have deletion hotspots in tumor suppressors FHIT/WWOX at chromosomal fragile sites FRA3B and FRA16D (which have elevated DSB rates) flanked by paired homologous DRs and inverted repeats (IR). Overall, these data provide novel insights into the MMR-dependent HeR inhibition mechanism and its role in tumor suppression. PMID:29069730

The carcinogenic air pollutant 3-nitrobenzanthrone induces GC to TA transversion mutations in human p53 sequences.

Science.gov (United States)

vom Brocke, Jochen; Krais, Annette; Whibley, Catherine; Hollstein, Monica C; Schmeiser, Heinz H

2009-01-01

3-Nitrobenzanthrone (3-NBA) is a potent mutagen and a suspected human carcinogen present in particulate matter of diesel exhaust and ambient air pollution. Employing an assay with human p53 knock-in (Hupki) murine embryonic fibroblasts (HUFs), we examined p53 mutations induced by 3-NBA and its active metabolite, N-hydroxy-3-aminobenzanthrone (N-OH-3-ABA). Twenty-nine immortalized cultures (cell lines) from 89 HUF primary cultures exposed at passage 1 for 5 days to 2 microM 3-NBA harboured 22 different mutations in the human DNA-binding domain sequence of the Hupki p53 tumour suppressor gene. The most frequently observed mutation was GC to TA transversion (46%), corroborating previous mutation studies with 3-NBA, and consistent with the presence of persistent 3-NBA-guanosine adducts found in DNA of exposed rodents. Six of the transversions found solely in 3-NBA-treated HUFs have not been detected thus far in untreated HUFs, but have been found repeatedly in human lung tumours. (32)P-post-labelling adduct analysis of DNA from HUF cells treated with 2 microM 3-NBA for 5 days showed a pattern similar to that found in vivo, indicating the metabolic competence of HUF cells to metabolize 3-NBA to electrophilic intermediates. Total DNA binding was 160 +/- 56 per 10(7) normal nucleotides with N(2)-guanosine being the major adduct. In contrast, identical treatment with N-OH-3-ABA resulted in a 100-fold lower level of specific DNA adducts and no carcinogen-specific mutation pattern in the Hupki assay. This indicates that the level of DNA adduct formation by the mutagen is critical to obtain specific mutation spectra in the assay. Our results are consistent with previous experiments in Muta Mouse and are compatible with the possibility that diesel exhaust exposure contributes to mutation load in humans and to lung cancer risk.

MicroRNA-193b-3p acts as a tumor suppressor by targeting the MYB oncogene in T-cell acute lymphoblastic leukemia.

Science.gov (United States)

Mets, E; Van der Meulen, J; Van Peer, G; Boice, M; Mestdagh, P; Van de Walle, I; Lammens, T; Goossens, S; De Moerloose, B; Benoit, Y; Van Roy, N; Clappier, E; Poppe, B; Vandesompele, J; Wendel, H-G; Taghon, T; Rondou, P; Soulier, J; Van Vlierberghe, P; Speleman, F

2015-04-01

The MYB oncogene is a leucine zipper transcription factor essential for normal and malignant hematopoiesis. In T-cell acute lymphoblastic leukemia (T-ALL), elevated MYB levels can arise directly through T-cell receptor-mediated MYB translocations, genomic MYB duplications or enhanced TAL1 complex binding at the MYB locus or indirectly through the TAL1/miR-223/FBXW7 regulatory axis. In this study, we used an unbiased MYB 3'untranslated region-microRNA (miRNA) library screen and identified 33 putative MYB-targeting miRNAs. Subsequently, transcriptome data from two independent T-ALL cohorts and different subsets of normal T-cells were used to select miRNAs with relevance in the context of normal and malignant T-cell transformation. Hereby, miR-193b-3p was identified as a novel bona fide tumor-suppressor miRNA that targets MYB during malignant T-cell transformation thereby offering an entry point for efficient MYB targeting-oriented therapies for human T-ALL.

The potyviral suppressor of RNA silencing confers enhanced resistance to multiple pathogens

International Nuclear Information System (INIS)

Pruss, Gail J.; Lawrence, Christopher B.; Bass, Troy; Li Qingshun Q.; Bowman, Lewis H.; Vance, Vicki

2004-01-01

Helper component-protease (HC-Pro) is a plant viral suppressor of RNA silencing, and transgenic tobacco expressing HC-Pro has increased susceptibility to a broad range of viral pathogens. Here we report that these plants also exhibit enhanced resistance to unrelated heterologous pathogens. Tobacco mosaic virus (TMV) infection of HC-Pro-expressing plants carrying the N resistance gene results in fewer and smaller lesions compared to controls without HC-Pro. The resistance to TMV is compromised but not eliminated by expression of nahG, which prevents accumulation of salicylic acid (SA), an important defense signaling molecule. HC-Pro-expressing plants are also more resistant to tomato black ring nepovirus (TBRV) and to the oomycete Peronospora tabacina. Enhanced TBRV resistance is SA-independent, whereas the response to P. tabacina is associated with early induction of markers characteristic of SA-dependent defense. Thus, a plant viral suppressor of RNA silencing enhances resistance to multiple pathogens via both SA-dependent and SA-independent mechanisms

The potyviral suppressor of RNA silencing confers enhanced resistance to multiple pathogens.

Science.gov (United States)

Pruss, Gail J; Lawrence, Christopher B; Bass, Troy; Li, Qingshun Q; Bowman, Lewis H; Vance, Vicki

2004-03-01

Helper component-protease (HC-Pro) is a plant viral suppressor of RNA silencing, and transgenic tobacco expressing HC-Pro has increased susceptibility to a broad range of viral pathogens. Here we report that these plants also exhibit enhanced resistance to unrelated heterologous pathogens. Tobacco mosaic virus (TMV) infection of HC-Pro-expressing plants carrying the N resistance gene results in fewer and smaller lesions compared to controls without HC-Pro. The resistance to TMV is compromised but not eliminated by expression of nahG, which prevents accumulation of salicylic acid (SA), an important defense signaling molecule. HC-Pro-expressing plants are also more resistant to tomato black ring nepovirus (TBRV) and to the oomycete Peronospora tabacina. Enhanced TBRV resistance is SA-independent, whereas the response to P. tabacina is associated with early induction of markers characteristic of SA-dependent defense. Thus, a plant viral suppressor of RNA silencing enhances resistance to multiple pathogens via both SA-dependent and SA-independent mechanisms.

Noise suppression and crosstalk analysis of on-chip magnetic film-type noise suppressor

Science.gov (United States)

Ma, Jingyan; Muroga, Sho; Endo, Yasushi; Hashi, Shuichiro; Naoe, Masayuki; Yokoyama, Hiroo; Hayashi, Yoshiaki; Ishiyama, Kazushi

2018-05-01

This paper discusses near field, conduction and crosstalk noise suppression of magnetic films with uniaxial anisotropy on transmission lines for a film-type noise suppressor in the GHz frequency range. The electromagnetic noise suppressions of magnetic films with different permeability and resistivity were measured and simulated with simple microstrip lines. The experimental and simulated results of Co-Zr-Nb and CoPd-CaF2 films agreed with each other. The results indicate that the higher permeability leads to a better near field shielding, and in the frequency range of 2-7 GHz, a higher conduction noise suppression. It also suggests that the higher resistivity results in a better crosstalk suppression in the frequency range below 2 GHz. These results can support the design guidelines of the magnetic film-type noise suppressor used in the next generation IC chip.

Identification and Functional Analysis of Gene Regulatory Sequences Interacting with Colorectal Tumor Suppressors

DEFF Research Database (Denmark)

Dahlgaard, Katja; Troelsen, Jesper

2018-01-01

Several tumor suppressors possess gene regulatory activity. Here, we describe how promoter and promoter/enhancer reporter assays can be used to characterize a colorectal tumor suppressor proteins’ gene regulatory activity of possible target genes. In the first part, a bioinformatic approach...... of the quick and efficient In-Fusion cloning method, and how to carry out transient transfections of Caco-2 colon cancer cells with the produced luciferase reporter plasmids using polyethyleneimine (PEI). A plan describing how to set up and carry out the luciferase expression assay is presented. The luciferase...... to identify relevant gene regulatory regions of potential target genes is presented. In the second part, it is demonstrated how to prepare and carry out the functional assay. We explain how to clone the bioinformatically identified gene regulatory regions into luciferase reporter plasmids by the use...

Weakener of white (Wow), a gene that modifies the expression of the white eye color locus and that suppresses position effect variegation in Drosophila melanogaster.

Science.gov (United States)

Birchler, J A; Bhadra, U; Rabinow, L; Linsk, R; Nguyen-Huynh, A T

1994-08-01

A locus is described in Drosophila melanogaster that modifies the expression of the white eye color gene. This trans-acting modifier reduces the expression of the white gene in the eye, but elevates the expression in other adult tissues. Because of the eye phenotype in which the expression of white is lessened but not eliminated, the newly described locus is called the Weakener of white (Wow). Northern analysis reveals that Wow can exert an inverse or direct modifying effect depending upon the developmental stage. Two related genes, brown and scarlet, that are coordinately expressed with white, are also affected by Wow. In addition, Wow modulates the steady state RNA level of the retrotransposon, copia. When tested with a white promoter-Alcohol dehydrogenase reporter. Wow confers the modifying effect to the reporter, suggesting a requirement of the white regulatory sequences for mediating the response. In addition to being a dosage sensitive regulator of white, brown, scarlet and copia, Wow acts as a suppressor of position effect variegation. There are many dosage sensitive suppressors of position effect variegation and many dosage-sensitive modifiers of gene expression. The Wow mutations provide evidence for an overlap between the two types of modifiers.

Common ataxia telangiectasia mutated haplotypes and risk of breast cancer: a nested case–control study

International Nuclear Information System (INIS)

Tamimi, Rulla M; Hankinson, Susan E; Spiegelman, Donna; Kraft, Peter; Colditz, Graham A; Hunter, David J

2004-01-01

The ataxia telangiectasia mutated (ATM) gene is a tumor suppressor gene with functions in cell cycle arrest, apoptosis, and repair of DNA double-strand breaks. Based on family studies, women heterozygous for mutations in the ATM gene are reported to have a fourfold to fivefold increased risk of breast cancer compared with noncarriers of the mutations, although not all studies have confirmed this association. Haplotype analysis has been suggested as an efficient method for investigating the role of common variation in the ATM gene and breast cancer. Five biallelic haplotype tagging single nucleotide polymorphisms are estimated to capture 99% of the haplotype diversity in Caucasian populations. We conducted a nested case–control study of breast cancer within the Nurses' Health Study cohort to address the role of common ATM haplotypes and breast cancer. Cases and controls were genotyped for five haplotype tagging single nucleotide polymorphisms. Haplotypes were predicted for 1309 cases and 1761 controls for which genotype information was available. Six unique haplotypes were predicted in this study, five of which occur at a frequency of 5% or greater. The overall distribution of haplotypes was not significantly different between cases and controls (χ 2 = 3.43, five degrees of freedom, P = 0.63). There was no evidence that common haplotypes of ATM are associated with breast cancer risk. Extensive single nucleotide polymorphism detection using the entire genomic sequence of ATM will be necessary to rule out less common variation in ATM and sporadic breast cancer risk

Novel APC gene mutations associated with protein alteration in diffuse type gastric cancer.

Science.gov (United States)

Ghatak, Souvik; Chakraborty, Payel; Sarkar, Sandeep Roy; Chowdhury, Biswajit; Bhaumik, Arup; Kumar, Nachimuthu Senthil

2017-06-02

The role of adenomatous polyposis coli (APC) gene in mitosis might be critical for regulation of genomic stability and chromosome segregation. APC gene mutations have been associated to have a role in colon cancer and since gastric and colon tumors share some common genetic lesions, it is relevant to investigate the role of APC tumor suppressor gene in gastric cancer. We investigated for somatic mutations in the Exons 14 and 15 of APC gene from 40 diffuse type gastric cancersamples. Rabbit polyclonal anti-APC antibody was used, which detects the wild-type APC protein and was recommended for detection of the respective protein in human tissues. Cell cycle analysis was done from tumor and adjacent normal tissue. APC immunoreactivity showed positive expression of the protein in stages I, II, III and negative expression in Stages III and IV. Two novel deleterious variations (g.127576C > A, g.127583C > T) in exon 14 sequence were found to generate stop codon (Y622* and Q625*)in the tumor samples. Due to the generation of stop codon, the APC protein might be truncated and all the regulatory features could be lost which has led to the down-regulation of protein expression. Our results indicate that aneuploidy might occurdue to the codon 622 and 625 APC-driven gastric tumorigenesis, in agreement with our cell cycle analysis. The APC gene function in mitosis and chromosomal stability might be lost and G1 might be arrested with high quantity of DNA in the S phase. Six missense somatic mutations in tumor samples were detected in exon 15 A-B, twoof which showed pathological and disease causing effects based on SIFT, Polyphen2 and SNPs & GO score and were not previously reported in the literature or the public mutation databases. The two novel pathological somatic mutations (g.127576C > A, g.127583C > T) in exon 14 might be altering the protein expression leading to development of gastric cancer in the study population. Our study showed that mutations in the APC

Alterations of tumor suppressor genes (Rb, p16, p27 and p53) and an increased FDG uptake in lung cancer

International Nuclear Information System (INIS)

Sasaki, Masayuki; Sugio, Kenji; Kuwabara, Yasuo

2003-01-01

The FDG uptake in lung cancer is considered to reflect the degree of malignancy, while alterations of some tumor suppressor genes are considered to be related to the malignant biological behavior of tumors. The aim of this study is to examine the relationship between FDG-PET and alterations in the tumor suppression genes of lung cancer. We examined 28 patients with primary lung cancer who underwent FDG-PET before surgery consisting of 17 patients with adenocarcinoma, 10 with squamous cell carcinoma and 1 with large cell carcinoma. The FDG-PET findings were evaluated based on the standardized uptake value (SUV). Alterations in the tumor suppressor genes, Rb, p16, p27 and p53, were evaluated immunohistochemically. The FDG uptake in lung cancer with alteration in each tumor suppressor gene tended to be higher than in those genes without alterations, although the differences were not significant. In 15 tumors with alterations in either tumor suppressor genes, the FDG uptake was 6.83±3.21. On the other hand, the mean FDG uptake was 1.95 in 2 tumors without alterations in any genes. The difference in the FDG uptake between the 2 groups was statistically significant (p<0.001). In conclusion, the presence of abnormalities in the tumor suppressor genes, which results in an accelerated cell proliferation, is thus considered to increase the FDG uptake in lung cancer. (author)

Immunoregulatory changes induced by total lymphoid irradiation. II. Development of thymus-leukemia antigen-positive and -negative suppressor T cells that differ in their regulatory function

International Nuclear Information System (INIS)

King, D.P.; Strober, S.

1981-01-01

BALB/c mice treated with total lymphoid irradiation (TLI) develop non-antigen-specific suppressor cells of the adoptive secondary antibody response and of the mixed leukocyte reaction. Suppressors of the adoptive anti-DNP response were eliminated by incubation of spleen cells with anti-Thy-1.2 or anti-thymus-leukemia (TL) antiserum and complement before cell transfer. Thymectomy before TLI prevented the appearance of the latter suppressor cells. On the other hand, suppressors of the MLR were eliminated by incubation of spleen cells with anti-Thy-1.2 but not anti-TL antiserum and complement. Thymectomy before TLI did not prevent their subsequent development. Thus, two subpopulations of suppressor T cells that differ in the expression of the TL surface antigen, dependence on the presence of the thymus, and in regulatory functions develop after TLI. The TL+, thymus-dependent cell suppresses the adoptive antibody response, and the TL-, thymus-independent cell suppresses the MLR

[Identification of novel compound heterozygous mutations of USH2A gene in a family with Usher syndrome type II].

Science.gov (United States)

Jiang, Haiou; Ge, Chuanqin; Wang, Yiwang; Tang, Genyun; Quan, Qingli

2015-06-01

To identify potential mutations in a Chinese family with Usher syndrome type II. Genomic DNA was obtained from two affected and four unaffected members of the family and subjected to amplification of the entire coding sequence and splicing sites of USH2A gene. Mutation detection was conducted by direct sequencing of the PCR products. A total of 100 normal unrelated individuals were used as controls. The patients were identified to be a compound heterozygote for two mutations: c.8272G>T (p.E2758X) in exon 42 from his mother and c.12376-12378ACT>TAA(p.T4126X) in exon 63 of the USH2A gene from his father. Both mutations were not found in either of the two unaffected family members or 100 unrelated controls, and had completely co-segregated with the disease phenotype in the family. Neither mutation has been reported in the HGMD database. The novel compound heterozygous mutations c.8272G>T and c.12376-12378ACT>TAA within the USH2A gene may be responsible for the disease. This result may provide new clues for molecular diagnosis of this disease.

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.

Mass spectrometric and mutational analyses reveal Lys-6-linked polyubiquitin chains catalyzed by BRCA1-BARD1 ubiquitin ligase.

Science.gov (United States)

Nishikawa, Hiroyuki; Ooka, Seido; Sato, Ko; Arima, Kei; Okamoto, Joji; Klevit, Rachel E; Fukuda, Mamoru; Ohta, Tomohiko

2004-02-06

The breast and ovarian cancer suppressor BRCA1 acquires significant ubiquitin ligase activity when bound to BARD1 as a RING heterodimer. Although the activity may well be important for the role of BRCA1 as a tumor suppressor, the biochemical consequence of the activity is not yet known. Here we report that BRCA1-BARD1 catalyzes Lys-6-linked polyubiquitin chain formation. K6R mutation of ubiquitin dramatically reduces the polyubiquitin products mediated by BRCA1-BARD1 in vitro. BRCA1-BARD1 preferentially utilizes ubiquitin with a single Lys residue at Lys-6 or Lys-29 to mediate autoubiquitination of BRCA1 in vivo. Furthermore, mass spectrometry analysis identified the Lys-6-linked branched ubiquitin fragment from the polyubiquitin chain produced by BRCA1-BARD1 using wild type ubiquitin. The BRCA1-BARD1-mediated Lys-6-linked polyubiquitin chains are deubiquitinated by 26 S proteasome in vitro, whereas autoubiquitinated CUL1 through Lys-48-linked polyubiquitin chains is degraded. Proteasome inhibitors do not alter the steady state level of the autoubiquitinated BRCA1 in vivo. Hence, the results indicate that BRCA1-BARD1 mediates novel polyubiquitin chains that may be distinctly edited by 26 S proteasome from conventional Lys-48-linked polyubiquitin chains.

Effect of irradiation on human T-cell proliferation: low dose irradiation stimulates mitogen-induced proliferation and function of the suppressor/cytotoxic T-cell subset

International Nuclear Information System (INIS)

Gualde, N.; Goodwin, J.S.

1984-01-01

Unfractionated human T cells exposed to 10-50 rad of X irradiation incorporated less [ 3 H]thymidine than nonirradiated T cells when subsequently cultured with PHA or Con A. The cytotoxic/suppressor T-cell subset, isolated as either OKT8(+) or OKT4(-) cells, demonstrated significantly enhanced [ 3 H]thymidine incorporation in PHA- or Con A-stimulated cultures after exposure to 10-50 rad, compared to unirradiated cells, while the proliferation of the OKT4(+) helper/inducer subset was inhibited by low dose irradiation. It has been previously reported that approximately 30% of the cytotoxic/suppressor subset also stains with OKM1. When the cytotoxic/suppressor subset was further subdivided into OKT4(-), OKM1(+), and OKT4(-), OKM1(-) cells, proliferation of the OKT4(-), OKM1(+) population was inhibited by exposure to 25 rad while proliferation of the OKT4(-), OKM1(-) population was stimulated. The increase in proliferation of the cytotoxic/suppressor T-cell subset after low dose irradiation is paralleled by an increase in suppressor activity of these cells. T cells exposed to 25 rad and then cultured with Con A for 48 hr caused greater inhibition of IgG production when added to fresh autologous lymphocytes stimulated by pokeweed mitogen than did unirradiated cells. Thus, low dose irradiation enhances both the proliferation and function of the human suppressor T-cell subset

The SDH mutation database: an online resource for succinate dehydrogenase sequence variants involved in pheochromocytoma, paraganglioma and mitochondrial complex II deficiency

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Devilee Peter

2005-11-01

Full Text Available Abstract Background The SDHA, SDHB, SDHC and SDHD genes encode the subunits of succinate dehydrogenase (succinate: ubiquinone oxidoreductase, a component of both the Krebs cycle and the mitochondrial respiratory chain. SDHA, a flavoprotein and SDHB, an iron-sulfur protein together constitute the catalytic domain, while SDHC and SDHD encode membrane anchors that allow the complex to participate in the respiratory chain as complex II. Germline mutations of SDHD and SDHB are a major cause of the hereditary forms of the tumors paraganglioma and pheochromocytoma. The largest subunit, SDHA, is mutated in patients with Leigh syndrome and late-onset optic atrophy, but has not as yet been identified as a factor in hereditary cancer. Description The SDH mutation database is based on the recently described Leiden Open (source Variation Database (LOVD system. The variants currently described in the database were extracted from the published literature and in some cases annotated to conform to current mutation nomenclature. Researchers can also directly submit new sequence variants online. Since the identification of SDHD, SDHC, and SDHB as classic tumor suppressor genes in 2000 and 2001, studies from research groups around the world have identified a total of 120 variants. Here we introduce all reported paraganglioma and pheochromocytoma related sequence variations in these genes, in addition to all reported mutations of SDHA. The database is now accessible online. Conclusion The SDH mutation database offers a valuable tool and resource for clinicians involved in the treatment of patients with paraganglioma-pheochromocytoma, clinical geneticists needing an overview of current knowledge, and geneticists and other researchers needing a solid foundation for further exploration of both these tumor syndromes and SDHA-related phenotypes.

Plasmid pKM101-dependent repair and mutagenesis in Escherichia coli cells with mutations lexB30 tif and zab-53 in the recA gene

International Nuclear Information System (INIS)

Blanco, M.; Rebollo, J.E.

1981-01-01

Bacterial survival after UV irradiation was increased in E. coli K12 lex B30 and tif zab-53 mutants harboring plasmid pKM101. Mutagenesis in response to UV was observed in these bacteria which, in absence of pKM101, are not UV-mutable. The mutator effect observed in unirradiated wild-type cells containing pKM101 was higher after incubation at 30 0 C with adenine than at 37 0 C. This effect was still enhanced by tif mutation, even in the tif zab-53 strain, but it was abolished by lexB30 mutation. In the tif zab-53 (pKM101) strain, repair and mutagenesis of UV-irradiated phage lambda was observed, but not in the lexB30 mutant carrying pKM101. The pKM101 mutant, pGW1, was unable to protect tif zab-53 bacteria against killing by UV, whereas the protection of lexB30 was intermediate; moreover, it did not promote the mutator effect at 30 0 C or enhance phage repair and mutagenesis in tif zab-53 cells. All UV-induced bacterial mutations in lexB30 (pKM101) strain were suppressors; in contrast, true revertants were found after UV irradiation of the tif zab-53 (pKM101) cells. (orig./AJ)

Cyclophosphamide-induced myeloid-derived suppressor cell population is immunosuppressive but not identical to myeloid-derived suppressor cells induced by growing TC-1 tumors

Czech Academy of Sciences Publication Activity Database

Mikyšková, Romana; Indrová, Marie; Polláková, Veronika; Bieblová, Jana; Šímová, Jana; Reiniš, Milan

2012-01-01

Roč. 35, č. 5 (2012), s. 374-384 ISSN 1524-9557 R&D Projects: GA ČR(CZ) GPP301/11/P220; GA ČR GA301/09/1024; GA ČR GA301/07/1410 EU Projects: European Commission(XE) 18933 - CLINIGENE Institutional research plan: CEZ:AV0Z50520514 Institutional support: RVO:68378050 Keywords : myeloid-derived suppressor cells * cyclophosphamide * all-trans-retinoic acid * IL-12 * HPV16 Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 3.463, year: 2012

Analysis of the interaction between human RITA and Drosophila Suppressor of Hairless.

Science.gov (United States)

Brockmann, Birgit; Mastel, Helena; Oswald, Franz; Maier, Dieter

2014-12-01

Notch signalling mediates intercellular communication, which is effected by the transcription factor CSL, an acronym for vertebrate CBF1/RBP-J, Drosophila Suppressor of Hairless [Su(H)] and C. elegans Lag1. Nuclear import of CBF1/RBP-J depends on co-activators and co-repressors, whereas the export relies on RITA. RITA is a tubulin and CBF1/RBP-J binding protein acting as a negative regulator of Notch signalling in vertebrates. RITA protein is highly conserved in eumatazoa, but no Drosophila homologue was yet identified. In this work, the activity of human RITA in the fly was addressed. To this end, we generated transgenic flies that allow a tissue specific induction of human RITA, which was demonstrated by Western blotting and in fly tissues. Unexpectedly, overexpression of RITA during fly development had little phenotypic consequences, even when overexpressed simultaneously with either Su(H) or the Notch antagonist Hairless. We demonstrate the in vivo binding of human RITA to Su(H) and to tubulin by co-immune precipitation. Moreover, RITA and tubulin co-localized to some degree in several Drosophila tissues. Overall our data show that human RITA, albeit binding to Drosophila Su(H) and tubulin, cannot influence the Notch signalling pathway in the fly, suggesting that a nuclear export mechanism of Su(H), if existent in Drosophila, does not depend on RITA. © 2015 The Authors.

The histone lysine methyltransferase KMT2D sustains a gene expression program that represses B cell lymphoma development.

Science.gov (United States)

Ortega-Molina, Ana; Boss, Isaac W; Canela, Andres; Pan, Heng; Jiang, Yanwen; Zhao, Chunying; Jiang, Man; Hu, Deqing; Agirre, Xabier; Niesvizky, Itamar; Lee, Ji-Eun; Chen, Hua-Tang; Ennishi, Daisuke; Scott, David W; Mottok, Anja; Hother, Christoffer; Liu, Shichong; Cao, Xing-Jun; Tam, Wayne; Shaknovich, Rita; Garcia, Benjamin A; Gascoyne, Randy D; Ge, Kai; Shilatifard, Ali; Elemento, Olivier; Nussenzweig, Andre; Melnick, Ari M; Wendel, Hans-Guido

2015-10-01

The gene encoding the lysine-specific histone methyltransferase KMT2D has emerged as one of the most frequently mutated genes in follicular lymphoma and diffuse large B cell lymphoma; however, the biological consequences of KMT2D mutations on lymphoma development are not known. Here we show that KMT2D functions as a bona fide tumor suppressor and that its genetic ablation in B cells promotes lymphoma development in mice. KMT2D deficiency also delays germinal center involution and impedes B cell differentiation and class switch recombination. Integrative genomic analyses indicate that KMT2D affects methylation of lysine 4 on histone H3 (H3K4) and expression of a set of genes, including those in the CD40, JAK-STAT, Toll-like receptor and B cell receptor signaling pathways. Notably, other KMT2D target genes include frequently mutated tumor suppressor genes such as TNFAIP3, SOCS3 and TNFRSF14. Therefore, KMT2D mutations may promote malignant outgrowth by perturbing the expression of tumor suppressor genes that control B cell-activating pathways.

System and method for multi-stage bypass, low operating temperature suppressor for automatic weapons

Science.gov (United States)

Moss, William C.; Anderson, Andrew T.

2015-06-09

The present disclosure relates to a suppressor for use with a weapon. The suppressor may be formed to have a body portion having a bore extending concentric with a bore axis of the weapon barrel. An opening in the bore extends at least substantially circumferentially around the bore. A flow path communicates with the opening and defines a channel for redirecting gasses flowing in the bore out from the bore, through the opening, into a rearward direction in the flow path. The flow path raises a pressure at the opening to generate a Mach disk within the bore at a location approximately coincident with the opening. The Mach disk forms as a virtual baffle to divert at least a portion of the gasses into the opening and into the flow path.

Proton cross-talk and losses in the dispersion suppressor regions at the FCC-hh

CERN Document Server

AUTHOR|(CDS)2100784; Appleby, Robert Barrie; Krainer, Alexander; Langner, Andy Sven; Abelleira, Jose

2017-01-01

Protons that collide at the interaction points of the FCC-hh may contribute to the background in the subsequent detector. Due to the high luminosity of the proton beams this may be of concern. Using DPMJET-III to model 50 TeV proton-proton collisions, tracking studies have been performed with PTC and MERLIN in order to gauge the elastic and inelastic proton cross-talk. High arc losses, particularly in the dispersion suppressor regions, have been revealed. These losses originate mainly from particles with a momentum deviation, either from interaction with a primary collimator in the betatron cleaning insertion, or from the proton-proton collisions. This issue can be mitigated by introducing additional collimators in the dispersion suppressor region. The specific design, lattice integration, and the effect of these collimators on cross-talk is assessed.

Survey of chloroquine-resistant mutations in the Plasmodium falciparum pfcrt and pfmdr-1 genes in Hadhramout, Yemen.

Science.gov (United States)

Bamaga, Omar A A; Mahdy, Mohammed A K; Lim, Yvonne A L

2015-09-01

Malaria is still a major public health problem in Yemen. More than 95% of the malaria cases are due to Plasmodium ‎falciparum‎. Recently in Yemen, the antimalarial treatment policy was changed from chloroquine (CQ) to artemisinin combination therapy (ACTs). However, CQ is still available and prescribed in the Yemeni market. The persistence of CQ resistance will be prolonged if the shift to ACT and the simultaneous withdrawal of CQ are not rigorously implemented. The aim of the current survey is to detect chloroquine-resistant mutations in P. falciparum chloroquine-resistance transporter (pfcrt) and P. falciparum multi-drug resistance-1 (pfmdr1) genes. These data will be important for future monitoring and assessment of antimalarial drug policy in Yemen. Blood specimens were collected from 735 individuals from different districts of the Hadhramout province, Yemen by house-to-house visit. Mutation-specific nested polymerase chain reaction (PCR) and restriction fragment length polymorphism (PCR-RFLP) methods were used to investigate the mutations in the pfmdr1(codons 86 and 1246) and pfcrt (codons 76, 271, 326, 356 and 371) genes. The overall prevalence of pfcrt mutations at codons 76, 271, 326 and 371 were 50.4%, 58.7%, 54.3% and 44.9%, respectively. All isolates had wild-type pfcrt 356 allele. The majority of pfmdr1 86 alleles (83.3%) and all pfmdr1 1246 alleles were wild type. There was no association between pfcrt mutations and symptomatology, gender and age groups. In conclusion, point mutations in codons 76, 271, 326 and 371 of pfcrt of P. falciparum are high suggesting a sustained high CQ resistance even after 4 years of shifting to ACTs. These findings warrant complete withdrawal of CQ use from the Yemeni market for P. falciparum and careful usage of CQ for treating Plasmodium vivax. Copyright © 2015 Elsevier B.V. All rights reserved.

Genomic Deletion at 10q23 in Prostate Cancer: More Than PTEN Loss?

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Raghavendra Tejo Karthik Poluri

2018-06-01

Full Text Available The PTEN gene encodes for the phosphatase and tensin homolog; it is a tumor suppressor gene that is among the most frequently inactivated genes throughout the human cancer spectrum. The most recent sequencing approaches have allowed the identification of PTEN genomic alterations, including deletion, mutation, or rearrangement in about 50% of prostate cancer (PCa cases. It appears that mechanisms leading to PTEN inactivation are cancer-specific, comprising gene mutations, small insertions/deletions, copy number alterations (CNAs, promoter hypermethylation, and RNA interference. The examination of publicly available results from deep-sequencing studies of various cancers showed that PCa appears to be the only cancer in which PTEN is lost mostly through CNA. Instead of inactivating mutations, which are seen in other cancers, deletion of the 10q23 locus is the most common form of PTEN inactivation in PCa. By investigating the minimal deleted region at 10q23, several other genes appear to be lost simultaneously with PTEN. Expression data indicate that, like PTEN, these genes are also downregulated upon loss of 10q23. These analyses raise the possibility that 10q23 is lost upon selective pressure not only to inactivate PTEN but also to impair the expression of surrounding genes. As such, several genes from this deleted region, which represents about 500 kb, may also act as tumor suppressors in PCa, requiring further studies on their respective functions in that context.

Mutations in Plasmodium falciparum K13 propeller gene from Bangladesh (2009–2013)

OpenAIRE

Mohon, Abu Naser; Alam, Mohammad Shafiul; Bayih, Abebe Genetu; Folefoc, Asongna; Shahinas, Dea; Haque, Rashidul; Pillai, Dylan R

2014-01-01

Background Bangladesh is a malaria hypo-endemic country sharing borders with India and Myanmar. Artemisinin combination therapy (ACT) remains successful in Bangladesh. An increase of artemisinin-resistant malaria parasites on the Thai-Cambodia and Thai-Myanmar borders is worrisome. K13 propeller gene (PF3D7_1343700 or PF13_0238) mutations have been linked to both in vitro artemisinin resistance and in vivo slow parasite clearance rates. This group undertook to evaluate if mutations seen in Ca...

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.

CD40 dependent exacerbation of immune mediated hepatitis by hepatic CD11b+ Gr-1+ myeloid derived suppressor cells in tumor bearing mice

Science.gov (United States)

Kapanadze, Tamar; Medina-Echeverz, José; Gamrekelashvili, Jaba; Weiss, Jonathan M.; Wiltrout, Robert H.; Kapoor, Veena; Hawk, Nga; Terabe, Masaki; Berzofsky, Jay A.; Manns, Michael P.; Wang, Ena; Marincola, Francesco M.; Korangy, Firouzeh; Greten, Tim F.

2015-01-01

Immunosuppressive CD11b+Gr-1+ myeloid-derived suppressor cells (MDSC) accumulate in the livers of tumor-bearing mice. We studied hepatic MDSC in two murine models of immune mediated hepatitis. Unexpectedly, treatment of tumor bearing mice with Concanavalin A or α-Galactosylceramide resulted in increased ALT and AST serum levels in comparison to tumor free mice. Adoptive transfer of hepatic MDSC into naïve mice exacerbated Concanavalin A induced liver damage. Hepatic CD11b+Gr-1+ cells revealed a polarized pro-inflammatory gene signature after Concanavalin A treatment. An interferon gamma- dependent up-regulation of CD40 on hepatic CD11b+Gr-1+ cells along with an up-regulation of CD80, CD86, and CD1d after Concanavalin A treatment was observed. Concanavalin A treatment resulted in a loss of suppressor function by tumor-induced CD11b+Gr-1+ MDSC as well as enhanced reactive oxygen species-mediated hepatotoxicity. CD40 knockdown in hepatic MDSC led to increased arginase activity upon Concanavalin A treatment and lower ALT/AST serum levels. Finally, blockade of arginase activity in Cd40−/− tumor-induced myeloid cells resulted in exacerbation of hepatitis and increased reactive oxygen species production in vivo. Our findings indicate that in a setting of acute hepatitis, tumor-induced hepatic MDSC act as pro-inflammatory immune effector cells capable of killing hepatocytes in a CD40-dependent manner. PMID:25616156

Somatic mitochondrial DNA mutations in cancer escape purifying selection and high pathogenicity mutations lead to the oncocytic phenotype: pathogenicity analysis of reported somatic mtDNA mutations in tumors

International Nuclear Information System (INIS)

Pereira, Luísa; Soares, Pedro; Máximo, Valdemar; Samuels, David C

2012-01-01

The presence of somatic mitochondrial DNA (mtDNA) mutations in cancer cells has been interpreted in controversial ways, ranging from random neutral accumulation of mutations, to positive selection for high pathogenicity, or conversely to purifying selection against high pathogenicity variants as occurs at the population level. Here we evaluated the predicted pathogenicity of somatic mtDNA mutations described in cancer and compare these to the distribution of variations observed in the global human population and all possible protein variations that could occur in human mtDNA. We focus on oncocytic tumors, which are clearly associated with mitochondrial dysfunction. The protein variant pathogenicity was predicted using two computational methods, MutPred and SNPs&GO. The pathogenicity score of the somatic mtDNA variants were significantly higher in oncocytic tumors compared to non-oncocytic tumors. Variations in subunits of Complex I of the electron transfer chain were significantly more common in tumors with the oncocytic phenotype, while variations in Complex V subunits were significantly more common in non-oncocytic tumors. Our results show that the somatic mtDNA mutations reported over all tumors are indistinguishable from a random selection from the set of all possible amino acid variations, and have therefore escaped the effects of purifying selection that act strongly at the population level. We show that the pathogenicity of somatic mtDNA mutations is a determining factor for the oncocytic phenotype. The opposite associations of the Complex I and Complex V variants with the oncocytic and non-oncocytic tumors implies that low mitochondrial membrane potential may play an important role in determining the oncocytic phenotype

GluD1 is a common altered player in neuronal differentiation from both MECP2-mutated and CDKL5-mutated iPS cells.

Science.gov (United States)

Livide, Gabriella; Patriarchi, Tommaso; Amenduni, Mariangela; Amabile, Sonia; Yasui, Dag; Calcagno, Eleonora; Lo Rizzo, Caterina; De Falco, Giulia; Ulivieri, Cristina; Ariani, Francesca; Mari, Francesca; Mencarelli, Maria Antonietta; Hell, Johannes Wilhelm; Renieri, Alessandra; Meloni, Ilaria

2015-02-01

Rett syndrome is a monogenic disease due to de novo mutations in either MECP2 or CDKL5 genes. In spite of their involvement in the same disease, a functional interaction between the two genes has not been proven. MeCP2 is a transcriptional regulator; CDKL5 encodes for a kinase protein that might be involved in the regulation of gene expression. Therefore, we hypothesized that mutations affecting the two genes may lead to similar phenotypes by dysregulating the expression of common genes. To test this hypothesis we used induced pluripotent stem (iPS) cells derived from fibroblasts of one Rett patient with a MECP2 mutation (p.Arg306Cys) and two patients with mutations in CDKL5 (p.Gln347Ter and p.Thr288Ile). Expression profiling was performed in CDKL5-mutated cells and genes of interest were confirmed by real-time RT-PCR in both CDKL5- and MECP2-mutated cells. The only major change in gene expression common to MECP2- and CDKL5-mutated cells was for GRID1, encoding for glutamate D1 receptor (GluD1), a member of the δ-family of ionotropic glutamate receptors. GluD1 does not form AMPA or NMDA glutamate receptors. It acts like an adhesion molecule by linking the postsynaptic and presynaptic compartments, preferentially inducing the inhibitory presynaptic differentiation of cortical neurons. Our results demonstrate that GRID1 expression is downregulated in both MECP2- and CDKL5-mutated iPS cells and upregulated in neuronal precursors and mature neurons. These data provide novel insights into disease pathophysiology and identify possible new targets for therapeutic treatment of Rett syndrome.

Parasites and deleterious mutations: interactions influencing the evolutionary maintenance of sex.

Science.gov (United States)

Park, A W; Jokela, J; Michalakis, Y

2010-05-01

The restrictive assumptions associated with purely genetic and purely ecological mechanisms suggest that neither of the two forces, in isolation, can offer a general explanation for the evolutionary maintenance of sex. Consequently, attention has turned to pluralistic models (i.e. models that apply both ecological and genetic mechanisms). Existing research has shown that combining mutation accumulation and parasitism allows restrictive assumptions about genetic and parasite parameter values to be relaxed while still predicting the maintenance of sex. However, several empirical studies have shown that deleterious mutations and parasitism can reduce fitness to a greater extent than would be expected if the two acted independently. We show how interactions between these genetic and ecological forces can completely reverse predictions about the evolution of reproductive modes. Moreover, we demonstrate that synergistic interactions between infection and deleterious mutations can render sex evolutionarily stable even when there is antagonistic epistasis among deleterious mutations, thereby widening the conditions for the evolutionary maintenance of sex.

Coordinating ERK signaling via the molecular scaffold Kinase Suppressor of Ras [version 1; referees: 2 approved

Directory of Open Access Journals (Sweden)

Danielle Frodyma

2017-08-01

Full Text Available Many cancers, including those of the colon, lung, and pancreas, depend upon the signaling pathways induced by mutated and constitutively active Ras. The molecular scaffolds Kinase Suppressor of Ras 1 and 2 (KSR1 and KSR2 play potent roles in promoting Ras-mediated signaling through the Raf/MEK/ERK kinase cascade. Here we summarize the canonical role of KSR in cells, including its central role as a scaffold protein for the Raf/MEK/ERK kinase cascade, its regulation of various cellular pathways mediated through different binding partners, and the phenotypic consequences of KSR1 or KSR2 genetic inactivation. Mammalian KSR proteins have a demonstrated role in cellular and organismal energy balance with implications for cancer and obesity. Targeting KSR1 in cancer using small molecule inhibitors has potential for therapy with reduced toxicity to the patient. RNAi and small molecule screens using KSR1 as a reference standard have the potential to expose and target vulnerabilities in cancer. Interestingly, although KSR1 and KSR2 are similar in structure, KSR2 has a distinct physiological role in regulating energy balance. Although KSR proteins have been studied for two decades, additional analysis is required to elucidate both the regulation of these molecular scaffolds and their potent effect on the spatial and temporal control of ERK activation in health and disease.

A rice gid1 suppressor mutant reveals that gibberellin is not always required for interaction between its receptor, GID1, and DELLA proteins.

Science.gov (United States)

Yamamoto, Yuko; Hirai, Takaaki; Yamamoto, Eiji; Kawamura, Mayuko; Sato, Tomomi; Kitano, Hidemi; Matsuoka, Makoto; Ueguchi-Tanaka, Miyako

2010-11-01

To investigate gibberellin (GA) signaling using the rice (Oryza sativa) GA receptor GIBBERELLIN-INSENSITIVE DWARF1 (GID1) mutant gid1-8, we isolated a suppressor mutant, Suppressor of gid1-1 (Sgd-1). Sgd-1 is an intragenic mutant containing the original gid1-8 mutation (L45F) and an additional amino acid substitution (P99S) in the loop region. GID1(P99S) interacts with the rice DELLA protein SLENDER RICE1 (SLR1), even in the absence of GA. Substitution of the 99th Pro with other amino acids revealed that substitution with Ala (P99A) caused the highest level of GA-independent interaction. Physicochemical analysis using surface plasmon resonance revealed that GID1(P99A) has smaller K(a) (association) and K(d) (dissociation) values for GA(4) than does wild-type GID1. This suggests that the GID1(P99A) lid is at least partially closed, resulting in both GA-independent and GA-hypersensitive interactions with SLR1. One of the three Arabidopsis thaliana GID1s, At GID1b, can also interact with DELLA proteins in the absence of GA, so we investigated whether GA-independent interaction of At GID1b depends on a mechanism similar to that of rice GID1(P99A). Substitution of the loop region or a few amino acids of At GID1b with those of At GID1a diminished its GA-independent interaction with GAI while maintaining the GA-dependent interaction. Soybean (Glycine max) and Brassica napus also have GID1s similar to At GID1b, indicating that these unique GID1s occur in various dicots and may have important functions in these plants.

In vivo and in vitro functional characterization of Andersen's syndrome mutations.

Science.gov (United States)

Bendahhou, Saïd; Fournier, Emmanuel; Sternberg, Damien; Bassez, Guillaume; Furby, Alain; Sereni, Carole; Donaldson, Matthew R; Larroque, Marie-Madeleine; Fontaine, Bertrand; Barhanin, Jacques

2005-06-15

The inward rectifier K(+) channel Kir2.1 carries all Andersen's syndrome mutations identified to date. Patients exhibit symptoms of periodic paralysis, cardiac dysrhythmia and multiple dysmorphic features. Here, we report the clinical manifestations found in three families with Andersen's syndrome. Molecular genetics analysis identified two novel missense mutations in the KCNJ2 gene leading to amino acid changes C154F and T309I of the Kir2.1 open reading frame. Patch clamp experiments showed that the two mutations produced a loss of channel function. When co-expressed with Kir2.1 wild-type (WT) channels, both mutations exerted a dominant-negative effect leading to a loss of the inward rectifying K(+) current. Confocal microscopy imaging in HEK293 cells is consistent with a co-assembly of the EGFP-fused mutant proteins with WT channels and proper traffick to the plasma membrane to produce silent channels alone or as hetero-tetramers with WT. Functional expression in C2C12 muscle cell line of newly as well as previously reported Andersen's syndrome mutations confirmed that these mutations act through a dominant-negative effect by altering channel gating or trafficking. Finally, in vivo electromyographic evaluation showed a decrease in muscle excitability in Andersen's syndrome patients. We hypothesize that Andersen's syndrome-associated mutations and hypokalaemic periodic paralysis-associated calcium channel mutations may lead to muscle membrane hypoexcitability via a common mechanism.

A phosphatase-independent gain-of-function mutation in PTEN triggers aberrant cell growth in astrocytes through an autocrine IGF-1 loop.

Science.gov (United States)

Fernández, S; Genis, L; Torres-Alemán, I

2014-08-07

Loss-of-function mutations in the phosphatase PTEN (phosphatase and tensin homolog deleted on chromosome10) contribute to aberrant cell growth in part through upregulation of the mitogenic IGF-1/PI3K/Akt pathway. In turn, this pathway exerts a homeostatic feedback over PTEN. Using mutagenesis analysis to explore a possible impact of this mutual control on astrocyte growth, we found that truncation of the C-terminal region of PTEN (Δ51) associates with a marked increase in NFκB activity, a transcription factor overactivated in astrocyte tumors. Whereas mutations of PTEN are considered to lead to a loss-of-function, PTENΔ51, a truncation that comprises a region frequently mutated in human gliomas, displayed a neomorphic (gain-of-function) activity that was independent of its phosphatase activity. This gain-of-function of PTENΔ51 includes stimulation of IGF-1 synthesis through protein kinase A activation of the IGF-1 promoter. Increased IGF-1 originates an autocrine loop that activates Akt and NFκB. Constitutive activation of NFκB in PTENΔ51-expressing astrocytes leads to aberrant cell growth; astrocytes expressing this mutant PTEN generate colonies in vitro and tumors in vivo. Mutations converting a tumor suppressor such as PTEN into a tumor promoter through a gain-of-function involving IGF-1 production may further our understanding of the role played by this growth factor in glioma growth and help us define druggable targets for personalized therapy.

Comparison of the suppressor cells found in the spleens of 89Sr-treated mice and in normal murine bone marrow

International Nuclear Information System (INIS)

Levy, E.M.; Corvese, J.S.; Bennett, M.

1981-01-01

Normal murine bone marrow cells and spleen cells of mice treated with 89 Sr both have suppressive activity. These nonspecific suppressor cells inhibit the ability of normal spleen cells to undergo antibody responses in vitro. After being precultured for 24 hr, these cells will also suppress antibody responses in vivo and the responses of normal spleen cells to T and B cell mitogens in vitro. These cells have previously been shown not to be mature T or B lymphocytes or macrophages. Velocity sedimentation and cell-size analysis indicated that both suppressor cells are large (approx. =206 μ 3 ). Mitomycin C treatment eliminated the ability of both suppressor cells to inhibit an in vitro antibody response. In contrast, this treatment did not reduce the ability of the cells to inhibit an in vitro antibody response. In contrast, this treatment did not reduce the ability of the cells to suppress a mitogenic response. Irradiation (1000 R) was also ineffective in eliminating the ability of either cell to suppress a mitogenic response. We conclude that the 2 suppressor cells are closely related if not identical, and we speculate that these cells may function in vivo to suppress immune reactivity in areas of intense hematopoiesis

ALDH2(E487K) mutation increases protein turnover and promotes murine hepatocarcinogenesis.

Science.gov (United States)

Jin, Shengfang; Chen, Jiang; Chen, Lizao; Histen, Gavin; Lin, Zhizhong; Gross, Stefan; Hixon, Jeffrey; Chen, Yue; Kung, Charles; Chen, Yiwei; Fu, Yufei; Lu, Yuxuan; Lin, Hui; Cai, Xiujun; Yang, Hua; Cairns, Rob A; Dorsch, Marion; Su, Shinsan M; Biller, Scott; Mak, Tak W; Cang, Yong

2015-07-21

Mitochondrial aldehyde dehydrogenase 2 (ALDH2) in the liver removes toxic aldehydes including acetaldehyde, an intermediate of ethanol metabolism. Nearly 40% of East Asians inherit an inactive ALDH2*2 variant, which has a lysine-for-glutamate substitution at position 487 (E487K), and show a characteristic alcohol flush reaction after drinking and a higher risk for gastrointestinal cancers. Here we report the characterization of knockin mice in which the ALDH2(E487K) mutation is inserted into the endogenous murine Aldh2 locus. These mutants recapitulate essentially all human phenotypes including impaired clearance of acetaldehyde, increased sensitivity to acute or chronic alcohol-induced toxicity, and reduced ALDH2 expression due to a dominant-negative effect of the mutation. When treated with a chemical carcinogen, these mutants exhibit increased DNA damage response in hepatocytes, pronounced liver injury, and accelerated development of hepatocellular carcinoma (HCC). Importantly, ALDH2 protein levels are also significantly lower in patient HCC than in peritumor or normal liver tissues. Our results reveal that ALDH2 functions as a tumor suppressor by maintaining genomic stability in the liver, and the common human ALDH2 variant would present a significant risk factor for hepatocarcinogenesis. Our study suggests that the ALDH2*2 allele-alcohol interaction may be an even greater human public health hazard than previously appreciated.

A Novel WT1 Gene Mutation in a Three-Generation Family with Progressive Isolated Focal Segmental Glomerulosclerosis

Science.gov (United States)

Caridi, Gianluca; Malaventura, Cristina; Dagnino, Monica; Leonardi, Emanuela; Artifoni, Lina; Ghiggeri, Gian Marco; Tosatto, Silvio C.E.; Murer, Luisa

2010-01-01

Background and objectives: Wilms tumor-suppressor gene-1 (WT1) plays a key role in kidney development and function. WT1 mutations usually occur in exons 8 and 9 and are associated with Denys-Drash, or in intron 9 and are associated with Frasier syndrome. However, overlapping clinical and molecular features have been reported. Few familial cases have been described, with intrafamilial variability. Sporadic cases of WT1 mutations in isolated diffuse mesangial sclerosis or focal segmental glomerulosclerosis have also been reported. Design, setting, participants, & measurements: Molecular analysis of WT1 exons 8 and 9 was carried out in five members on three generations of a family with late-onset isolated proteinuria. The effect of the detected amino acid substitution on WT1 protein's structure was studied by bioinformatics tools. Results: Three family members reached end-stage renal disease in full adulthood. None had genital abnormalities or Wilms tumor. Histologic analysis in two subjects revealed focal segmental glomerulosclerosis. The novel sequence variant c.1208G>A in WT1 exon 9 was identified in all of the affected members of the family. Conclusions: The lack of Wilms tumor or other related phenotypes suggests the expansion of WT1 gene analysis in patients with focal segmental glomerulosclerosis, regardless of age or presence of typical Denys-Drash or Frasier syndrome clinical features. Structural analysis of the mutated protein revealed that the mutation hampers zinc finger-DNA interactions, impairing target gene transcription. This finding opens up new issues about WT1 function in the maintenance of the complex gene network that regulates normal podocyte function. PMID:20150449

High-precision, whole-genome sequencing of laboratory strains facilitates genetic studies.

Directory of Open Access Journals (Sweden)

Anjana Srivatsan

2008-08-01

Full Text Available Whole-genome sequencing is a powerful technique for obtaining the reference sequence information of multiple organisms. Its use can be dramatically expanded to rapidly identify genomic variations, which can be linked with phenotypes to obtain biological insights. We explored these potential applications using the emerging next-generation sequencing platform Solexa Genome Analyzer, and the well-characterized model bacterium Bacillus subtilis. Combining sequencing with experimental verification, we first improved the accuracy of the published sequence of the B. subtilis reference strain 168, then obtained sequences of multiple related laboratory strains and different isolates of each strain. This provides a framework for comparing the divergence between different laboratory strains and between their individual isolates. We also demonstrated the power of Solexa sequencing by using its results to predict a defect in the citrate signal transduction pathway of a common laboratory strain, which we verified experimentally. Finally, we examined the molecular nature of spontaneously generated mutations that suppress the growth defect caused by deletion of the stringent response mediator relA. Using whole-genome sequencing, we rapidly mapped these suppressor mutations to two small homologs of relA. Interestingly, stable suppressor strains had mutations in both genes, with each mutation alone partially relieving the relA growth defect. This supports an intriguing three-locus interaction module that is not easily identifiable through traditional suppressor mapping. We conclude that whole-genome sequencing can drastically accelerate the identification of suppressor mutations and complex genetic interactions, and it can be applied as a standard tool to investigate the genetic traits of model organisms.

Immunoregulatory T cells in man. Histamine-induced suppressor T cells are derived from a Leu 2+ (T8+) subpopulation distinct from that which gives rise to cytotoxic T cells

International Nuclear Information System (INIS)

Sansoni, P.; Silverman, E.D.; Khan, M.M.; Melmon, K.L.; Engleman, E.G.

1985-01-01

One mechanism of histamine-mediated inhibition of the immune response in man is to activate T suppressor cells that bear the Leu 2 (OKT8) marker. The current study was undertaken to characterize the histamine-induced suppressor cell using a monoclonal antibody (9.3) shown previously to distinguish cytotoxic T cells from antigen-specific suppressor T cells. Leu 2+ cells isolated from peripheral blood were further separated with antibody 9.3 into Leu 2+, 9.3+, and Leu 2+, 9.3- subsets and each subset was incubated with different concentrations of histamine before determining their ability to suppress immune responses in vitro. The results indicate that the Leu 2+, 9.3- subpopulation includes all histamine-induced suppressor cells, that 10(-4) M histamine is the optimal concentration for suppressor cell induction, and that exposure of Leu 2+, 9.3- cells to histamine for 30 s is sufficient to initiate the induction process. After treatment with histamine these cells inhibit both phytohemagglutinin-induced T cell proliferation and pokeweed mitogen-induced B cell differentiation. The suppression of phytohemagglutinin-induced proliferation was resistant to x-irradiation with 1,200 rad, either before or after histamine exposure, suggesting that Leu 2+, 9.3- cells need not proliferate to become suppressor cells or exert suppression. Moreover, suppression by these cells was not due to altered kinetics of the response. Finally, a histamine type 2 receptor antagonist (cimetidine) but not a type 1 receptor antagonist (mepyramine) blocked the induction of suppressor cells. On the basis of these results and our previous studies of antigen specific suppressor cells, we conclude that Leu 2+ suppressor cells in man are derived from a precursor pool that is phenotypically distinct from cells that can differentiate into cytotoxic T cells

Two mutations in the same low-density lipoprotein receptor allele act in synergy to reduce receptor function in heterozygous familial hypercholesterolemia

DEFF Research Database (Denmark)

Jensen, H K; Jensen, T G; Faergeman, O

1997-01-01

Mutations in genes are not necessarily pathogenic. Expression of mutant genes in cells can therefore be required to demonstrate that mutations in fact disturb protein function. This applies especially to missense mutations, which cause an amino acid to be replaced by another amino acid. In the pr...

Insulin induces suppressor of cytokine signaling-3 tyrosine phosphorylation through janus-activated kinase

NARCIS (Netherlands)

Peraldi, P; Filloux, C; Emanuelli, B; Hilton, DJ; Van Obberghen, E

2001-01-01

Suppressor of cytokine signaling (SOCS) proteins were originally described as cytokine-induced molecules involved in negative feedback loops. We have shown that SOCS-3 is also a component of the insulin signaling network (1), Indeed, insulin leads to SOCS-3 expression in 3T3-L1 adipocytes. Once

Nature of the suppressor cells mediating prolonged graft survival after administration of extracted histocompatibility antigen and cyclosporine

International Nuclear Information System (INIS)

Yoshimura, N.; Kahan, B.D.

1985-01-01

Antigen-specific suppressor T cells are induced by donor histocompatibility antigen extracted from spleen cells with 3M KCl combined with cyclosporine (Ag-CsA). A single i.v. injection of 5 mg 3M-KCl-extracted donor Buffalo (Buf, RT1b) antigen (Ag) combined with a three day course of CsA prolonged renal allograft survival in Wistar-Furth (WFu, RT1u) hosts to a greater extent (MST 26.5 days) than CsA alone (MST 11.8 days). Peripheral blood lymphocytes (PBL) or spleen cells harvested from Ag-CsA-treated recipients ten days after transplantation inhibited the mixed lymphocyte reaction (MLR) between normal responder WFu cells and irradiated Buf cells (55.6% and 64.4% suppression, respectively, P less than 0.025), but not third-party Brown-Norway (BN, RT1n) stimulator cells (13.6% and -18.3% suppression, respectively, NS). The suppressor effect was not mediated by cytolytic cells; there was neither primary nor secondary cytolytic activity against 51 Cr-labeled Con-A blastoid Buf cells. The suppressor cells were neither adherent to plastic dishes nor to nylon-wool columns. PBL irradiated with 800 rads, but not 1500 rads, suppressed the MLR. A single injection of cyclophosphamide (CY, 25 mg/kg) seven days after transplantation abrogated the suppression induced by Ag-CsA treatment. Moreover, PBL from Ag-CsA recipients failed to suppress the MLR, if depleted either of all T cells by treatment with monoclonal antibody (Mab) W3/13 HLK (pan T cells; % suppression -15.8), or of cytotoxic/suppressor cells with Mab OX-8 (-19.3% suppression) together with rabbit antimouse immunoglobulin and complement

Ser80Ile mutation and a concurrent Pro25Leu variant of the VHL gene in an extended Hungarian von Hippel-Lindau family

Directory of Open Access Journals (Sweden)

Fazakas Ferenc

2008-04-01

Full Text Available Abstract Von Hippel-Lindau disease (VHL is a rare autosomal dominant disease characterized by development of cystic and tumorous lesions at multiple sites, including the brain, spinal cord, kidneys, adrenals, pancreas, epididymis and eyes. The clinical phenotype results from molecular abnormalities of the VHL tumor suppressor gene, mapped to human chromosome 3p25-26. The VHL gene encodes two functionally active VHL proteins due to the presence of two translational initiation sites separated by 53 codons. The majority of disease-causing mutations have been detected downstream of the second translational initiation site, but there are conflicting data as to whether few mutations located in the first 53 codons, such as the Pro25Leu could have a pathogenic role. In this paper we report a large Hungarian VHL type 2 family consisting of 32 members in whom a disease-causing AGT80AAT (Ser80Ile c.239G>A, p.Ser80Ile mutation, but not the concurrent CCT25CTT (Pro25Leu c.74C>T, p.Pro25Leu variant co-segregated with the disease. To our knowledge, the Ser80Ile mutation has not been previously described in VHL type 2 patients with high risk of pheochromocytoma and renal cell cancer. Therefore, this finding represents a novel genotype-phenotype association and VHL kindreds with Ser80Ile mutation will require careful surveillance for pheochromocytoma. We concluded that the Pro25Leu variant is a rare, neutral variant, but the presence such a rare gene variant may make genetic counseling difficult.

Myxovirus resistance, osteopontin and suppressor of cytokine signaling 3 polymorphisms predict hepatitis C virus therapy response in an admixed patient population: comparison with IL28B.

Science.gov (United States)

Angelo, Ana Luiza Dias; Cavalcante, Lourianne Nascimento; Abe-Sandes, Kiyoko; Machado, Taísa Bonfim; Lemaire, Denise Carneiro; Malta, Fernanda; Pinho, João Renato; Lyra, Luiz Guilherme Costa; Lyra, Andre Castro

2013-10-01

Suppressor of cytokine signaling 3, myxovirus resistance protein and osteopontin gene polymorphisms may influence the therapeutic response in patients with chronic hepatitis C, and an association with IL28 might increase the power to predict sustained virologic response. Our aims were to evaluate the association between myxovirus resistance protein, osteopontin and suppressor of cytokine signaling 3 gene polymorphisms in combination with IL28B and to assess the therapy response in hepatitis C patients treated with pegylated-interferon plus ribavirin. Myxovirus resistance protein, osteopontin, suppressor of cytokine signaling 3 and IL28B polymorphisms were analyzed by PCR-restriction fragment length polymorphism, direct sequencing and real-time PCR. Ancestry was determined using genetic markers. We analyzed 181 individuals, including 52 who were sustained virologic responders. The protective genotype frequencies among the sustained virologic response group were as follows: the G/G suppressor of cytokine signaling 3 (rs4969170) (62.2%); T/T osteopontin (rs2853744) (60%); T/T osteopontin (rs11730582) (64.3%); and the G/T myxovirus resistance protein (rs2071430) genotype (54%). The patients who had ≥3 of the protective genotypes from the myxovirus resistance protein, the suppressor of cytokine signaling 3 and osteopontin had a greater than 90% probability of achieving a sustained response (pC/C IL28B genotype was present in 58.8% of the subjects in this group. The sustained virological response rates increased to 85.7% and 91.7% by analyzing C/C IL28B with the T/T osteopontin genotype at rs11730582 and the G/G suppressor of cytokine signaling 3 genotype, respectively. Genetic ancestry analysis revealed an admixed population. Hepatitis C genotype 1 patients who were responders to interferon-based therapy had a high frequency of multiple protective polymorphisms in the myxovirus resistance protein, osteopontin and suppressor of cytokine signaling 3 genes. The combined

A storage-protein marker associated with the suppressor of Pm8 for powdery mildew resistance in wheat.

Science.gov (United States)

Ren, S X; McIntosh, R A; Sharp, P J; The, T T

1996-11-01

A suppressor of resistance to powdery mildew conferred by Pm8 showed complete association with the presence of a storage-protein marker resolved by electrophoresis on SDS-PAGE gels. This marker was identified as the product of the gliadin allele Gli-A1a. The mildewresponse phenotypes of wheats possessing the 1BL.1RS translocation were completely predictable from electrophoretograms. The suppressor, designated SuPm8, was located on chromosome 1AS. It was specific in its suppression of Pm8, and did not affect the rye-derived resistance phenotypes of wheat lines with Pm17, also located in 1RS, or of lines with Pm7.

Mutations at the cysteine codons of the recA gene of Escherichia coli

International Nuclear Information System (INIS)

Weisemann, J.M.; Weinstock, G.M.

1988-01-01

Each of the three cysteine residues in the Escherichia coli RecA protein was replaced with a number of other amino acids. To do this, each cysteine codon was first converted to a chain-terminating amber codon by oligonucleotide-directed mutagenesis. These amber mutants were then either assayed for function in different suppressor strains or reverted by a second round of mutagenesis with oligonucleotides that had random sequences at the amber codon. Thirty-three different amino acid substitutions were obtained. Mutants were tested for three functions of RecA: survival following UV irradiation, homologous recombination, and induction of the SOS response. It was found that although none of the cysteines is essential for activity, mutations at each of these positions can affect one or more of the activities of RecA, depending on the particular amino acid substitution. In addition, the cysteine at position 116 appears to be involved in the RecA-promoted cleavage of the LexA protein

Coevolution within a transcriptional network by compensatory trans and cis mutations

KAUST Repository

Kuo, D.

2010-10-26

Transcriptional networks have been shown to evolve very rapidly, prompting questions as to how such changes arise and are tolerated. Recent comparisons of transcriptional networks across species have implicated variations in the cis-acting DNA sequences near genes as the main cause of divergence. What is less clear is how these changes interact with trans-acting changes occurring elsewhere in the genetic circuit. Here, we report the discovery of a system of compensatory trans and cis mutations in the yeast AP-1 transcriptional network that allows for conserved transcriptional regulation despite continued genetic change. We pinpoint a single species, the fungal pathogen Candida glabrata, in which a trans mutation has occurred very recently in a single AP-1 family member, distinguishing it from its Saccharomyces ortholog. Comparison of chromatin immunoprecipitation profiles between Candida and Saccharomyces shows that, despite their different DNA-binding domains, the AP-1 orthologs regulate a conserved block of genes. This conservation is enabled by concomitant changes in the cis-regulatory motifs upstream of each gene. Thus, both trans and cis mutations have perturbed the yeast AP-1 regulatory system in such a way as to compensate for one another. This demonstrates an example of “coevolution” between a DNA-binding transcription factor and its cis-regulatory site, reminiscent of the coevolution of protein binding partners.

PHTS, a novel putative tumor suppressor, is involved in the transformation reversion of HeLaHF cells independently of the p53 pathway

International Nuclear Information System (INIS)

Yu Dehua; Fan, Wufang; Liu, Guohong; Nguy, Vivian; Chatterton, Jon E.; Long Shilong; Ke, Ning; Meyhack, Bernd; Bruengger, Adrian; Brachat, Arndt; Wong-Staal, Flossie; Li, Qi-Xiang

2006-01-01

HeLaHF is a non-transformed revertant of HeLa cells, likely resulting from the activation of a putative tumor suppressor(s). p53 protein was stabilized in this revertant and reactivated for certain transactivation functions. Although p53 stabilization has not conclusively been linked to the reversion, it is clear that the genes in p53 pathway are involved. The present study confirms the direct role of p53 in HeLaHF reversion by demonstrating that RNAi-mediated p53 silencing partially restores anchorage-independent growth potential of the revertant through the suppression of anoikis. In addition, we identified a novel gene, named PHTS, with putative tumor suppressor properties, and showed that this gene is also involved in HeLaHF reversion independently of the p53 pathway. Expression profiling revealed that PHTS is one of the genes that is up-regulated in HeLaHF but not in HeLa. It encodes a putative protein with CD59-like domains. RNAi-mediated PHTS silencing resulted in the partial restoration of transformation (anchorage-independent growth) in HeLaHF cells, similar to that of p53 gene silencing, implying its tumor suppressor effect. However, the observed increased transformation potential by PHTS silencing appears to be due to an increased anchorage-independent proliferation rate rather than suppression of anoikis, unlike the effect of p53 silencing. p53 silencing did not affect PHTS gene expression, and vice versa, suggesting PHTS may function in a new and p53-independent tumor suppressor pathway. Furthermore, over-expression of PHTS in different cancer cell lines, in addition to HeLa, reduces cell growth likely via induced apoptosis, confirming the broad PHTS tumor suppressor properties

Novel autosomal dominant TNNT1 mutation causing nemaline myopathy.

Science.gov (United States)

Konersman, Chamindra G; Freyermuth, Fernande; Winder, Thomas L; Lawlor, Michael W; Lagier-Tourenne, Clotilde; Patel, Shailendra B

2017-11-01

Nemaline myopathy (NEM) is one of the three major forms of congenital myopathy and is characterized by diffuse muscle weakness, hypotonia, respiratory insufficiency, and the presence of nemaline rod structures on muscle biopsy. Mutations in troponin T1 (TNNT1) is 1 of 10 genes known to cause NEM. To date, only homozygous nonsense mutations or compound heterozygous truncating or internal deletion mutations in TNNT1 gene have been identified in NEM. This extended family is of historical importance as some members were reported in the 1960s as initial evidence that NEM is a hereditary disorder. Proband and extended family underwent Sanger sequencing for TNNT1. We performed RT-PCR and immunoblot on muscle to assess TNNT1 RNA expression and protein levels in proband and father. We report a novel heterozygous missense mutation of TNNT1 c.311A>T (p.E104V) that segregated in an autosomal dominant fashion in a large family residing in the United States. Extensive sequencing of the other known genes for NEM failed to identify any other mutant alleles. Muscle biopsies revealed a characteristic pattern of nemaline rods and severe myofiber hypotrophy that was almost entirely restricted to the type 1 fiber population. This novel mutation alters a residue that is highly conserved among vertebrates. This report highlights not only a family with autosomal dominant inheritance of NEM, but that this novel mutation likely acts via a dominant negative mechanism. © 2017 The Authors. Molecular Genetics & Genomic Medicine published by Wiley Periodicals, Inc.

Mechanisms of Hepatitis C Viral Resistance to Direct Acting Antivirals.

Science.gov (United States)

Ahmed, Asma; Felmlee, Daniel J

2015-12-18

There has been a remarkable transformation in the treatment of chronic hepatitis C in recent years with the development of direct acting antiviral agents targeting virus encoded proteins important for viral replication including NS3/4A, NS5A and NS5B. These agents have shown high sustained viral response (SVR) rates of more than 90% in phase 2 and phase 3 clinical trials; however, this is slightly lower in real-life cohorts. Hepatitis C virus resistant variants are seen in most patients who do not achieve SVR due to selection and outgrowth of resistant hepatitis C virus variants within a given host. These resistance associated mutations depend on the class of direct-acting antiviral drugs used and also vary between hepatitis C virus genotypes and subtypes. The understanding of these mutations has a clear clinical implication in terms of choice and combination of drugs used. In this review, we describe mechanism of action of currently available drugs and summarize clinically relevant resistance data.

Phosphoribosyl diphosphate synthetase-independent NAD de novo synthesis in Escherichia coli: a new phenotype of phosphate regulon mutants

DEFF Research Database (Denmark)

Hove-Jensen, Bjarne

1996-01-01

Phosphoribosyl diphosphate-lacking (Δprs) mutant strains of Escherichia coli require NAD, guanosine, uridine, histidine, and tryptophan for growth. NAD is required by phosphoribosyl diphosphate-lacking mutants because of lack of one of the substrates for the quinolinate phosphoribosyltransferase...... reaction, an enzyme of the NAD de novo pathway. Several NAD-independent mutants of a host from which prs had been deleted were isolated; all of them were shown to have lesions in the pstSCAB-phoU operon, in which mutations lead to derepression of the Pho regulon. In addition NAD-independent growth...... was dependent on a functional quinolinate phosphoribosyltransferase. The prs suppressor mutations led to the synthesis of a new phosphoryl compound that may act as a precursor for a new NAD biosynthetic pathway. This compound may be synthesized by the product of an unknown phosphate starvation-inducible gene...

15-Hydroxyprostaglandin dehydrogenase is an in vivo suppressor of colon tumorigenesis.

Science.gov (United States)

Myung, Seung-Jae; Rerko, Ronald M; Yan, Min; Platzer, Petra; Guda, Kishore; Dotson, Angela; Lawrence, Earl; Dannenberg, Andrew J; Lovgren, Alysia Kern; Luo, Guangbin; Pretlow, Theresa P; Newman, Robert A; Willis, Joseph; Dawson, Dawn; Markowitz, Sanford D

2006-08-08

15-Hydroxyprostaglandin dehydrogenase (15-PGDH) is a prostaglandin-degrading enzyme that is highly expressed in normal colon mucosa but is ubiquitously lost in human colon cancers. Herein, we demonstrate that 15-PGDH is active in vivo as a highly potent suppressor of colon neoplasia development and acts in the colon as a required physiologic antagonist of the prostaglandin-synthesizing activity of the cyclooxygenase 2 (COX-2) oncogene. We first show that 15-PGDH gene knockout induces a marked 7.6-fold increase in colon tumors arising in the Min (multiple intestinal neoplasia) mouse model. Furthermore, 15-PGDH gene knockout abrogates the normal resistance of C57BL/6J mice to colon tumor induction by the carcinogen azoxymethane (AOM), conferring susceptibility to AOM-induced adenomas and carcinomas in situ. Susceptibility to AOM-induced tumorigenesis is mediated by a marked induction of dysplasia, proliferation, and cyclin D1 expression throughout microscopic aberrant crypt foci arising in 15-PGDH null colons and is concomitant with a doubling of prostaglandin E(2) in 15-PGDH null colonic mucosa. A parallel role for 15-PGDH loss in promoting the earliest steps of colon neoplasia in humans is supported by our finding of a universal loss of 15-PGDH expression in microscopic colon adenomas recovered from patients with familial adenomatous polyposis, including adenomas as small as a single crypt. These models thus delineate the in vivo significance of 15-PGDH-mediated negative regulation of the COX-2 pathway and moreover reveal the particular importance of 15-PGDH in opposing the neoplastic progression of colonic aberrant crypt foci.

Novel insertion mutation of ABCB1 gene in an ivermectin-sensitive Border Collie

OpenAIRE

Han, Jae-Ik; Son, Hyoung-Won; Park, Seung-Cheol; Na, Ki-Jeong

2010-01-01

P-glycoprotein (P-gp) is encoded by the ABCB1 gene and acts as an efflux pump for xenobiotics. In the Border Collie, a nonsense mutation caused by a 4-base pair deletion in the ABCB1 gene is associated with a premature stop to P-gp synthesis. In this study, we examined the full-length coding sequence of the ABCB1 gene in an ivermectin-sensitive Border Collie that lacked the aforementioned deletion mutation. The sequence was compared to the corresponding sequences of a wild-type Beagle and sev...

Data on the recurrence of breast tumors fit a model in which dormant cells are subject to slow attrition but can randomly awaken to become malignant

DEFF Research Database (Denmark)

Stein, Wilfred D; Litman, Thomas

2006-01-01

appears to be a random event. Inasmuch as the kinetics of cancer recurrence in published data sets closely follows the model found for the appearance of sporadic retinoblastoma, tumor recurrence could be triggered by mutations in awakening- suppressor mechanisms. The retinoblastoma tumor suppressor gene...... was identified by tracing its occurrence in familial retinoblastoma pedigrees. Will it be possible to track the postulated cancer recurrence, awakening suppressor gene(s) in early recurrence breast cancer patients?...

Suppressor Effects in Coping Research with African American Adolescents from Low-Income Communities

Science.gov (United States)

Gaylord-Harden, Noni K.; Cunningham, Jamila A.; Holmbeck, Grayson N.; Grant, Kathryn E.

2010-01-01

Objective: The purpose of the current study was to demonstrate the replicable nature of statistical suppressor effects in coping research through 2 examples with African American adolescents from low-income communities. Method: Participants in the 1st example included 497 African American adolescents (mean age = 12.61 years, SD = 0.99; 57% female)…

The Enamovirus P0 protein is a silencing suppressor which inhibits local and systemic RNA silencing through AGO1 degradation

International Nuclear Information System (INIS)

Fusaro, Adriana F.; Correa, Regis L.; Nakasugi, Kenlee; Jackson, Craig; Kawchuk, Lawrence; Vaslin, Maite F.S.; Waterhouse, Peter M.

2012-01-01

The P0 protein of poleroviruses and P1 protein of sobemoviruses suppress the plant's RNA silencing machinery. Here we identified a silencing suppressor protein (SSP), P0 PE , in the Enamovirus Pea enation mosaic virus-1 (PEMV-1) and showed that it and the P0s of poleroviruses Potato leaf roll virus and Cereal yellow dwarf virus have strong local and systemic SSP activity, while the P1 of Sobemovirus Southern bean mosaic virus supresses systemic silencing. The nuclear localized P0 PE has no discernable sequence conservation with known SSPs, but proved to be a strong suppressor of local silencing and a moderate suppressor of systemic silencing. Like the P0s from poleroviruses, P0 PE destabilizes AGO1 and this action is mediated by an F-box-like domain. Therefore, despite the lack of any sequence similarity, the poleroviral and enamoviral SSPs have a conserved mode of action upon the RNA silencing machinery.

The Enamovirus P0 protein is a silencing suppressor which inhibits local and systemic RNA silencing through AGO1 degradation

Energy Technology Data Exchange (ETDEWEB)

Fusaro, Adriana F. [University of Sydney, NSW 2006 (Australia); CSIRO Plant Industry, Canberra, P.O. Box 1600, ACT 2601 (Australia); Correa, Regis L. [CSIRO Plant Industry, Canberra, P.O. Box 1600, ACT 2601 (Australia); Depto. de Virologia, IMPPG, UFRJ, 21941-902 (Brazil); Nakasugi, Kenlee; Jackson, Craig [University of Sydney, NSW 2006 (Australia); Kawchuk, Lawrence [Research Centre, Agriculture and Agri-Food Canada, Lethbridge, AB T1J4B1 (Canada); Vaslin, Maite F.S. [Depto. de Virologia, IMPPG, UFRJ, 21941-902 (Brazil); Waterhouse, Peter M., E-mail: peter.waterhouse@sydney.edu.au [University of Sydney, NSW 2006 (Australia); CSIRO Plant Industry, Canberra, P.O. Box 1600, ACT 2601 (Australia)

2012-05-10

The P0 protein of poleroviruses and P1 protein of sobemoviruses suppress the plant's RNA silencing machinery. Here we identified a silencing suppressor protein (SSP), P0{sup PE}, in the Enamovirus Pea enation mosaic virus-1 (PEMV-1) and showed that it and the P0s of poleroviruses Potato leaf roll virus and Cereal yellow dwarf virus have strong local and systemic SSP activity, while the P1 of Sobemovirus Southern bean mosaic virus supresses systemic silencing. The nuclear localized P0{sup PE} has no discernable sequence conservation with known SSPs, but proved to be a strong suppressor of local silencing and a moderate suppressor of systemic silencing. Like the P0s from poleroviruses, P0{sup PE} destabilizes AGO1 and this action is mediated by an F-box-like domain. Therefore, despite the lack of any sequence similarity, the poleroviral and enamoviral SSPs have a conserved mode of action upon the RNA silencing machinery.

Amino acid residues important for substrate specificity of the amino acid permeases Can I p and Gnp I p in Saccharomyces cerevisiae

DEFF Research Database (Denmark)

Regenberg, Birgitte; Kielland-Brandt, M.C.

2001-01-01

Deletion of the general amino acid permease gene GAP1 abolishes uptake of L-citrulline in Saccharomyces cerevisiae, resulting in the inability to grow on L-citrulline as sole nitrogen source. Selection for suppressor mutants that restored growth on L-citrulline led to isolation of 21 mutations...... in the arginine permease gene CAN1. One similar mutation was found in the glutamine-asparagine permease gene GNP1. L-[C-14]citrulline uptake measurements confirmed that suppressor mutations in CAN1 conferred uptake of this amino acid, while none of the mutant permeases had lost the ability to transport L-[C-14......]arginine. Substrate specificity seemed to remain narrow in most cases, and broad substrate specificity was only observed in the cases where mutations affect two proline residues (P148 and P313) that are both conserved in the amino acid-polyamine-choline (APC) transporter superfamily. We found mutations...

Polysaccharide from Lentinus edodes inhibits the immunosuppressive function of myeloid-derived suppressor cells.

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Hao Wu

Full Text Available Reversing the function of immune suppressor cells may improve the efficacy of cancer therapy. Here, we have isolated a novel polysaccharide MPSSS (577.2 Kd from Lentinus edodes and examined its effects on differentiation and function of myeloid-derived suppressor cells (MDSCs. MPSSS is composed of glucose (75.0%, galactose (11.7%, mannose (7.8%, and xylose (0.4%. In vivo, it inhibits the growth of McgR32 tumor cells, which is correlated with a reduced percentage of MDSCs in peripheral blood. In vitro, it induces both morphological and biophysical changes in MDSCs. Importantly, MPSSS up-regulates MHC II and F4/80 expression on MDSCs, and reverses their inhibition effect on CD4(+ T cells in a dose-dependent manner. The mechanism study shows that MPSSS may stimulate MDSCs through a MyD88 dependent NF-κB signaling pathway. Together, we demonstrated for the first time that MPSSS stimulates the differentiation of MDSCs and reverses its immunosuppressive functions, shedding new light on developing novel anti-cancer strategies by targeting MDSCs.

Sleep quality and methylation status of selected tumor suppressor genes among nurses and midwives.

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Bukowska-Damska, Agnieszka; Reszka, Edyta; Kaluzny, Pawel; Wieczorek, Edyta; Przybek, Monika; Zienolddiny, Shanbeh; Peplonska, Beata

2018-01-01

Chronic sleep restriction may affect metabolism, hormone secretion patterns and inflammatory responses. Limited reports suggest also epigenetic effects, such as changes in DNA methylation profiles. The study aims to assess the potential association between poor sleep quality or sleep duration and the levels of 5-methylcytosine in the promoter regions of selected tumor suppressor genes. A cross-sectional study was conducted on 710 nurses and midwives aged 40-60 years. Data from interviews regarding sleep habits and potential confounders were used. The methylation status of tumor suppressor genes was determined via qMSP reactions using DNA samples derived from leucocytes. No significant findings were observed in the total study population or in the two subgroups of women stratified by the current system of work. A borderline significance association was observed between a shorter duration of sleep and an increased methylation level in CDKN2A among day working nurses and midwives. Further studies are warranted to explore this under-investigated topic.

A Rice gid1 Suppressor Mutant Reveals That Gibberellin Is Not Always Required for Interaction between Its Receptor, GID1, and DELLA Proteins[W][OA

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Yamamoto, Yuko; Hirai, Takaaki; Yamamoto, Eiji; Kawamura, Mayuko; Sato, Tomomi; Kitano, Hidemi; Matsuoka, Makoto; Ueguchi-Tanaka, Miyako

2010-01-01

To investigate gibberellin (GA) signaling using the rice (Oryza sativa) GA receptor GIBBERELLIN-INSENSITIVE DWARF1 (GID1) mutant gid1-8, we isolated a suppressor mutant, Suppressor of gid1-1 (Sgd-1). Sgd-1 is an intragenic mutant containing the original gid1-8 mutation (L45F) and an additional amino acid substitution (P99S) in the loop region. GID1P99S interacts with the rice DELLA protein SLENDER RICE1 (SLR1), even in the absence of GA. Substitution of the 99th Pro with other amino acids revealed that substitution with Ala (P99A) caused the highest level of GA-independent interaction. Physicochemical analysis using surface plasmon resonance revealed that GID1P99A has smaller Ka (association) and Kd (dissociation) values for GA4 than does wild-type GID1. This suggests that the GID1P99A lid is at least partially closed, resulting in both GA-independent and GA-hypersensitive interactions with SLR1. One of the three Arabidopsis thaliana GID1s, At GID1b, can also interact with DELLA proteins in the absence of GA, so we investigated whether GA-independent interaction of At GID1b depends on a mechanism similar to that of rice GID1P99A. Substitution of the loop region or a few amino acids of At GID1b with those of At GID1a diminished its GA-independent interaction with GAI while maintaining the GA-dependent interaction. Soybean (Glycine max) and Brassica napus also have GID1s similar to At GID1b, indicating that these unique GID1s occur in various dicots and may have important functions in these plants. PMID:21098733

A novel germline mutation (c.A527G) in STK11 gene causes Peutz-Jeghers syndrome in a Chinese girl: A case report.

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Zhao, Zi-Ye; Jiang, Yu-Liang; Li, Bai-Rong; Yang, Fu; Li, Jing; Jin, Xiao-Wei; Sun, Shu-Han; Ning, Shou-Bin

2017-12-01

Peutz-Jeghers syndrome (PJS) is a Mendelian autosomal dominant disease caused by mutations in the tumor suppressor gene, serine/threonine kinase 11 (STK11). The features of this syndrome include gastrointestinal (GI) hamartomas, melanin spots on the lips and the extremities, and an increased risk of developing cancer. Early onset of disease is often characterized by mucocutaneous pigmentation and intussusception due to GI polyps in childhood. A girl with a positive family history grew oral pigmentation at 1 and got intussusception by small bowel hamartomas at 5. She was diagnosed with PJS based on oral pigmentation and a positive family history of PJS. Enteroscopy was employed to treat the GI polyps. Sanger sequencing was used to investigate STK11 mutation in this family. A large jejunal polyp together with other smaller ones was resected, and the girl recovered uneventfully. We discovered a heterozygous substitution in STK11, c.A527G in exon 4, in the girl and her father who was also a PJS patient, and the amine acid change was an aspartic acid-glycine substitution in codon 176. This mutation was not found in other healthy family members and 50 unrelated non-PJS controls, and it is not recorded in databases, which prove it a novel mutation. Evolutionary conservation analysis of amino acid residues showed this aspartic acid is a conserved one between species, and protein structure prediction by SWISS-MODEL indicated an obvious change in local structure. In addition, PolyPhen-2 score for this mutation is 1, which indicates it probably damaging. PJS can cause severe complication like intussusception in young children, and early screening for small bowel may be beneficial for these patients. The mutation of STK11 found in this girl is a novel one, which enlarges the spectrum of STK11. Our analysis supported it a causative one in PJS.

Genome-wide analysis of histone H3 acetylation patterns in AML identifies PRDX2 as an epigenetically silenced tumor suppressor gene

DEFF Research Database (Denmark)

Agrawal-Singh, Shuchi; Isken, Fabienne; Agelopoulos, Konstantin

2012-01-01

to have lower H3Ac levels in AML compared with progenitor cells, which suggested that a large number of genes are epigenetically silenced in AML. Intriguingly, we identified peroxiredoxin 2 (PRDX2) as a novel potential tumor suppressor gene in AML. H3Ac was decreased at the PRDX2 gene promoter in AML......With the use of ChIP on microarray assays in primary leukemia samples, we report that acute myeloid leukemia (AML) blasts exhibit significant alterations in histone H3 acetylation (H3Ac) levels at > 1000 genomic loci compared with CD34+ progenitor cells. Importantly, core promoter regions tended......, which correlated with low mRNA and protein expression. We also observed DNA hypermethylation at the PRDX2 promoter in AML. Low protein expression of the antioxidant PRDX2 gene was clinically associated with poor prognosis in patients with AML. Functionally, PRDX2 acted as inhibitor of myeloid cell...

Inhibition of tumor growth in syngenetic chimeric mice mediated by a depletion of suppressor T cells

International Nuclear Information System (INIS)

Rotter, V.; Trainin, N.

1975-01-01

Syngeneic chimeric (lethally irradiated and reconstituted with syngeneic bone marrow cells) mice manifested an increased resistance to the development of Lewis lung carcinoma. In addition, these mice had a higher response to polyvinylpyrrolidone and a reduced reactivity to T mitogens. The present findings suggest that syngeneic chimeric mice lack suppressor T cells shown to regulate the development of Lewis lung tumor and the response to polyvinylpyrrolidone. Other components of the T cell population, such as helper cells responding to sheep red blood cells or cells involved in allograft rejection, assayed in these syngeneic chimeras were found unaffected. The fact that chimeric mice are deficient in a certain suppressor T cell population whereas other T activities are normal suggests the existence of different cell lines within the T cell population. (U.S.)

Synergism in mutations induction in Tradescantia by plants protection agents acting jointly with ionizing radiation

International Nuclear Information System (INIS)

Cebulska-Wasilewska, A.; Smagala, J.

1990-01-01

Tradescantia was first treated by plants protection agents such as: Ambusz, Afalton, Ripcord, Decis, deltametryne and after that irradiated with X radiation. The synergism of both factors was observed. The mutation frequency dependence on radiation doses was studied. 7 figs., 4 refs. (A.S.)

The IARC TP53 mutation database: a resource for studying the significance of TP53 mutations in human cancers

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Magali Olivier

2007-02-01

Full Text Available

The tumor suppressor gene TP53 is frequently inactivated by gene mutations in many types of human sporadic cancers, and inherited TP53 mutations predispose to a wide spectrum of early-onset tumors (Li-Fraumeni et Li-Fraumenilike Syndromes. All TP53 gene variations (somatic and germline mutations, as well as polymorphisms that are reported in the scientific literature or in SNP databases are compiled in the IARC TP53 Database. This database provides structured data and analysis tools to study mutation patterns in human cancers and cell-lines and to investigate the clinical impact of mutations. It contains annotations related to the clinical and pathological characteristics of tumors, as well as the demographics and carcinogen exposure of patients. The IARC TP53 web site (http://www-p53.iarc.fr/ provides a search interface for the core database and includes a comprehensive user guide, a slideshow on TP53 mutations in human cancer, protocols and references for sequencing TP53 gene, and links to relevant publications and bioinformatics databases. The database interface allows download of entire data sets and propose various tools for the selection, analysis and downloads of specific sets of data according to user's query.

Recently, new annotations on the functional properties of mutant p53 proteins have been integrated in this database. Indeed, the most frequent TP53 alterations observed in cancers (75% are missense mutations that result in the production of a mutant protein that differ from the wildtype by one single amino-acid. The characterization of the biological activities of these mutant proteins is thus very important. Over the last ten years, a great amount of systematic data has been generated from experimental assays performed in

Promoter hypermethylation of the DNA repair gene O(6)-methylguanine-DNA methyltransferase is associated with the presence of G:C to A:T transition mutations in p53 in human colorectal tumorigenesis.

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Esteller, M; Risques, R A; Toyota, M; Capella, G; Moreno, V; Peinado, M A; Baylin, S B; Herman, J G

2001-06-15

Defects in DNA repair may be responsible for the genesis of mutations in key genes in cancer cells. The tumor suppressor gene p53 is commonly mutated in human cancer by missense point mutations, most of them G:C to A:T transitions. A recognized cause for this type of change is spontaneous deamination of the methylcytosine. However, the persistence of a premutagenic O(6)-methylguanine can also be invoked. This last lesion is removed in the normal cell by the DNA repair enzyme O(6)-methylguanine-DNA methyltransferase (MGMT). In many tumor types, epigenetic silencing of MGMT by promoter hypermethylation has been demonstrated and linked to the appearance of G to A mutations in the K-ras oncogene in colorectal tumors. To study the relevance of defective MGMT function by aberrant methylation in relation to the presence of p53 mutations, we studied 314 colorectal tumors for MGMT promoter hypermethylation and p53 mutational spectrum. Inactivation of MGMT by aberrant methylation was associated with the appearance of G:C to A:T transition mutations at p53 (Fischer's exact test, two-tailed; P = 0.01). Overall, MGMT methylated tumors displayed p53 transition mutations in 43 of 126 (34%) cases, whereas MGMT unmethylated tumors only showed G:C to A:T changes in 37 of 188 (19%) tumors. A more striking association was found in G:C to A:T transitions in non-CpG dinucleotides; 71% (12 of 17) of the total non-CpG transition mutations in p53 were observed in MGMT aberrantly methylated tumors (Fischer's exact test, two-tailed; P = 0.008). Our data suggest that epigenetic silencing of MGMT by promoter hypermethylation may lead to G:C to A:T transition mutations in p53.

No evidence for promoter region methylation of the succinate dehydrogenase and fumarate hydratase tumour suppressor genes in breast cancer

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Dobrovic Alexander

2009-09-01

Full Text Available Abstract Background Succinate dehydrogenase (SDH and fumarate hydratase (FH are tricarboxylic acid (TCA cycle enzymes that are also known to act as tumour suppressor genes. Increased succinate or fumarate levels as a consequence of SDH and FH deficiency inhibit hypoxia inducible factor-1α (HIF-1α prolyl hydroxylases leading to sustained HIF-1α expression in tumours. Since HIF-1α is frequently expressed in breast carcinomas, DNA methylation at the promoter regions of the SDHA, SDHB, SDHC and SDHD and FH genes was evaluated as a possible mechanism in silencing of SDH and FH expression in breast carcinomas. Findings No DNA methylation was identified in the promoter regions of the SDHA, SDHB, SDHC, SDHD and FH genes in 72 breast carcinomas and 10 breast cancer cell lines using methylation-sensitive high resolution melting which detects both homogeneous and heterogeneous methylation. Conclusion These results show that inactivation via DNA methylation of the promoter CpG islands of SDH and FH is unlikely to play a major role in sporadic breast carcinomas.

MicroRNA-218 functions as a tumor suppressor in lung cancer by targeting IL-6/STAT3 and negatively correlates with poor prognosis.

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Yang, Yan; Ding, Lili; Hu, Qun; Xia, Jia; Sun, Junjie; Wang, Xudong; Xiong, Hua; Gurbani, Deepak; Li, Lianbo; Liu, Yan; Liu, Aiguo

2017-08-22

Aberrant expression of microRNAs in different human cancer types has been widely reported. MiR-218 acts as a tumor suppressor in diverse human cancer types impacting regulation of multiple genes in oncogenic pathways. Here, we evaluated the expression and function of miR-218 in human lung cancer and ALDH positive lung cancer cells to understand the potential mechanisms responsible for disease pathology. Also, the association between its host genes and the target genes could be useful towards the better understanding of prognosis in clinical settings. Publicly-available data from The Cancer Genome Atlas (TCGA) was mined to compare the levels of miR-218 and its host gene SLIT2/3 between lung cancer tissues and normal lung tissues. Transfection of miR-218 to investigate its function in lung cancer cells was done and in vivo effects were determined using miR-218 expressing lentiviruses. Aldefluor assay and Flow cytometry was used to quantify and enrich ALDH positive lung cancer cells. Levels of miR-218, IL-6R, JAK3 and phosphorylated STAT3 were compared in ALDH1A1 positive and ALDH1A1 negative cells. Overexpression of miR-218 in ALDH positive cells was carried to test the survival by tumorsphere culture. Finally, utilizing TCGA data we studied the association of target genes of miR-218 with the prognosis of lung cancer. We observed that the expression of miR-218 was significantly down-regulated in lung cancer tissues compared to normal lung tissues. Overexpression of miR-218 decreased cell proliferation, invasion, colony formation, and tumor sphere formation in vitro and repressed tumor growth in vivo. We further found that miR-218 negatively regulated IL-6 receptor and JAK3 gene expression by directly targeting the 3'-UTR of their mRNAs. In addition, the levels of both miR-218 host genes and the components of IL-6/STAT3 pathway correlated with prognosis of lung cancer patients. MiR-218 acts as a tumor suppressor in lung cancer via IL-6/STAT3 signaling pathway

The von Hippel-Lindau tumor suppressor gene inhibits hepatocyte growth factor/scatter factor-induced invasion and branching morphogenesis in renal carcinoma cells.

Science.gov (United States)

Koochekpour, S; Jeffers, M; Wang, P H; Gong, C; Taylor, G A; Roessler, L M; Stearman, R; Vasselli, J R; Stetler-Stevenson, W G; Kaelin, W G; Linehan, W M; Klausner, R D; Gnarra, J R; Vande Woude, G F

1999-09-01

Loss of function in the von Hippel-Lindau (VHL) tumor suppressor gene occurs in familial and most sporadic renal cell carcinomas (RCCs). VHL has been linked to the regulation of cell cycle cessation (G(0)) and to control of expression of various mRNAs such as for vascular endothelial growth factor. RCC cells express the Met receptor tyrosine kinase, and Met mediates invasion and branching morphogenesis in many cell types in response to hepatocyte growth factor/scatter factor (HGF/SF). We examined the HGF/SF responsiveness of RCC cells containing endogenous mutated (mut) forms of the VHL protein (VHL-negative RCC) with that of isogenic cells expressing exogenous wild-type (wt) VHL (VHL-positive RCC). We found that VHL-negative 786-0 and UOK-101 RCC cells were highly invasive through growth factor-reduced (GFR) Matrigel-coated filters and exhibited an extensive branching morphogenesis phenotype in response to HGF/SF in the three-dimensional (3D) GFR Matrigel cultures. In contrast, the phenotypes of A498 VHL-negative RCC cells were weaker, and isogenic RCC cells ectopically expressing wt VHL did not respond at all. We found that all VHL-negative RCC cells expressed reduced levels of tissue inhibitor of metalloproteinase 2 (TIMP-2) relative to the wt VHL-positive cells, implicating VHL in the regulation of this molecule. However, consistent with the more invasive phenotype of the 786-0 and UOK-101 VHL-negative RCC cells, the levels of TIMP-1 and TIMP-2 were reduced and levels of the matrix metalloproteinases 2 and 9 were elevated compared to the noninvasive VHL-positive RCC cells. Moreover, recombinant TIMPs completely blocked HGF/SF-mediated branching morphogenesis, while neutralizing antibodies to the TIMPs stimulated HGF/SF-mediated invasion in vitro. Thus, the loss of the VHL tumor suppressor gene is central to changes that control tissue invasiveness, and a more invasive phenotype requires additional genetic changes seen in some but not all RCC lines. These

Mechanism of inhibition of growth hormone receptor signaling by suppressor of cytokine signaling proteins

DEFF Research Database (Denmark)

Hansen, J A; Lindberg, K; Hilton, D J

1999-01-01

In this study we have investigated the role of suppressor of cytokine signaling (SOCS) proteins in GH receptor-mediated signaling. GH-induced transcription was inhibited by SOCS-1 and SOCS-3, while SOCS-2 and cytokine inducible SH2-containing protein (CIS) had no effect By using chimeric SOCS pro...

Iro/IRX transcription factors negatively regulate Dpp/TGF-β pathway activity during intestinal tumorigenesis.

Science.gov (United States)

Martorell, Òscar; Barriga, Francisco M; Merlos-Suárez, Anna; Stephan-Otto Attolini, Camille; Casanova, Jordi; Batlle, Eduard; Sancho, Elena; Casali, Andreu

2014-11-01

Activating mutations in Wnt and EGFR/Ras signaling pathways are common in colorectal cancer (CRC). Remarkably, clonal co-activation of these pathways in the adult Drosophila midgut induces "tumor-like" overgrowths. Here, we show that, in these clones and in CRC cell lines, Dpp/TGF-β acts as a tumor suppressor. Moreover, we discover that the Iroquois/IRX-family-protein Mirror downregulates the transcription of core components of the Dpp pathway, reducing its tumor suppressor activity. We also show that this genetic interaction is conserved in human CRC cells, where the Iro/IRX proteins IRX3 and IRX5 diminish the response to TGF-β. IRX3 and IRX5 are upregulated in human adenomas, and their levels correlate inversely with the gene expression signature of response to TGF-β. In addition, Irx5 expression confers a growth advantage in the presence of TGF-β, but is selected against in its absence. Together, our results identify a set of Iro/IRX proteins as conserved negative regulators of Dpp/TGF-β activity. We propose that during the characteristic adenoma-to-carcinoma transition of human CRC, the activity of IRX proteins could reduce the sensitivity to the cytostatic effect of TGF-β, conferring a growth advantage to tumor cells prior to the acquisition of mutations in TGF-β pathway components. © 2014 The Authors.

Perturbation of PALB2 function by the T413S mutation found in small cell lung cancer [version 1; referees: 2 approved

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Jean-Yves Bleuyard

2017-11-01

Full Text Available Background: Germline mutations in the PALB2 gene are associated with the genetic disorder Fanconi anaemia and increased predisposition to cancer. Disease-associated variants are mainly protein-truncating mutations, whereas a few missense substitutions are reported to perturb its interaction with breast cancer susceptibility proteins BRCA1 and BRCA2, which play essential roles in homology-directed repair (HDR. More recently, PALB2 was shown to associate with active genes independently of BRCA1, and through this mechanism, safeguards these regions from DNA replicative stresses. However, it is unknown whether PALB2 tumour suppressor function requires its chromatin association. Methods: Mining the public database of cancer mutations, we identified four potentially deleterious cancer-associated missense mutations within the PALB2 chromatin association motif (ChAM. To assess the impact of these mutations on PALB2 function, we generated cell lines expressing PALB2 variants harbouring corresponding ChAM mutations, and evaluated PALB2 chromatin association properties and the cellular resistance to camptothecin (CPT. Additionally, we examined the accumulation of γH2A.X and the RAD51 recombinase as readouts of DNA damage signalling and HDR, respectively. Results: We demonstrate that a small-cell lung cancer (SCLC-associated T413S mutation in PALB2 impairs its chromatin association and confers reduced resistance to CPT, the only FDA-approved drug for relapsed SCLC. Unexpectedly, we found a less efficient γH2A.X nuclear foci formation in PALB2 T413S expressing cells, whereas a near-normal level of RAD51 nuclear foci was visible. Conclusions: These findings support the importance of PALB2 chromatin association in the suppression of tumours, including SCLC, an unusually aggressive type of cancer with poor prognosis. PALB2 T413S has little impact on RAD51 recruitment, likely due to its intact interaction with BRCA1 and BRCA2. However, this mutant shows

Perturbation of PALB2 function by the T413S mutation found in small cell lung cancer [version 2; referees: 3 approved

Directory of Open Access Journals (Sweden)

Jean-Yves Bleuyard

2018-01-01

Full Text Available Background: Germline mutations in the PALB2 gene are associated with the genetic disorder Fanconi anaemia and increased predisposition to cancer. Disease-associated variants are mainly protein-truncating mutations, whereas a few missense substitutions are reported to perturb its interaction with breast cancer susceptibility proteins BRCA1 and BRCA2, which play essential roles in homology-directed repair (HDR. More recently, PALB2 was shown to associate with active genes independently of BRCA1, and through this mechanism, safeguards these regions from DNA replicative stresses. However, it is unknown whether PALB2 tumour suppressor function requires its chromatin association. Methods: Mining the public database of cancer mutations, we identified four potentially deleterious cancer-associated missense mutations within the PALB2 chromatin association motif (ChAM. To assess the impact of these mutations on PALB2 function, we generated cell lines expressing PALB2 variants harbouring corresponding ChAM mutations, and evaluated PALB2 chromatin association properties and the cellular resistance to camptothecin (CPT. Additionally, we examined the accumulation of γH2A.X and the RAD51 recombinase as readouts of DNA damage signalling and HDR, respectively. Results: We demonstrate that a small-cell lung cancer (SCLC-associated T413S mutation in PALB2 impairs its chromatin association and confers reduced resistance to CPT, the only FDA-approved drug for relapsed SCLC. Unexpectedly, we found a less efficient γH2A.X nuclear foci formation in PALB2 T413S expressing cells, whereas a near-normal level of RAD51 nuclear foci was visible. Conclusions: These findings support the importance of PALB2 chromatin association in the suppression of tumours, including SCLC, an unusually aggressive type of cancer with poor prognosis. PALB2 T413S has little impact on RAD51 recruitment, likely due to its intact interaction with BRCA1 and BRCA2. However, this mutant shows

A multinodular goiter as the initial presentation of a renal cell carcinoma harbouring a novel VHL mutation

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Silva Eduardo

2006-10-01

Full Text Available Abstract Background Secondary involvement of the thyroid gland is rare. Often the origin of the tumor is difficult to identify from the material obtained by fine-needle aspiration cytology. Renal cell carcinoma of the clear-cell type is one of the more common carcinomas to metastasize to the thyroid gland. Somatic mutations of the von Hippel-Lindau tumor suppressor gene are associated with the sporadic form of this tumor. We aimed to illustrate the potential utility of DNA based technologies to search for specific molecular markers in order to establish the anatomic site of origin. Case Presentation A 54-yr-old Caucasian male complaining of a rapidly increasing neck tumor was diagnosed as having a clear-cell tumor by fine-needle aspiration cytology. A positive staining for cytokeratin as well as for vimentin and CD10 in the absence of staining for thyroglobulin, calcitonin and TTF1 suggested a renal origin confirmed by computed tomography. Using frozen RNA, obtained from cells left inside the needle used for fine needle aspiration cytology, it was possible to identify a somatic mutation (680 delA in the VHL gene. Conclusion In the presence of a clear-cell tumor of the thyroid gland, screening for somatic mutations in the VHL gene in material derived from thyroid aspirates might provide additional information to immunocytochemical studies and therefore plays a contributory role to establish the final diagnosis. Moreover, in a near future, this piece of information might be useful to define a targeted therapy.

Next generation sequencing of Cytokeratin 20-negative Merkel cell carcinoma reveals ultraviolet-signature mutations and recurrent TP53 and RB1 inactivation.

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Harms, Paul W; Collie, Angela M B; Hovelson, Daniel H; Cani, Andi K; Verhaegen, Monique E; Patel, Rajiv M; Fullen, Douglas R; Omata, Kei; Dlugosz, Andrzej A; Tomlins, Scott A; Billings, Steven D

2016-03-01

Merkel cell carcinoma is a rare but highly aggressive cutaneous neuroendocrine carcinoma. Cytokeratin 20 (CK20) is expressed in ~95% of Merkel cell carcinomas and is useful for distinction from morphologically similar entities including metastatic small-cell lung carcinoma. Lack of CK20 expression may make diagnosis of Merkel cell carcinoma more challenging, and has unknown biological significance. Approximately 80% of CK20-positive Merkel cell carcinomas are associated with the oncogenic Merkel cell polyomavirus. Merkel cell carcinomas lacking Merkel cell polyomavirus display distinct genetic changes from Merkel cell polyomavirus-positive Merkel cell carcinoma, including RB1 inactivating mutations. Unlike CK20-positive Merkel cell carcinoma, the majority of CK20-negative Merkel cell carcinomas are Merkel cell polyomavirus-negative, suggesting CK20-negative Merkel cell carcinomas predominantly arise through virus-independent pathway(s) and may harbor additional genetic differences from conventional Merkel cell carcinoma. Hence, we analyzed 15 CK20-negative Merkel cell carcinoma tumors (10 Merkel cell polyomavirus-negative, four Merkel cell polyomavirus-positive, and one undetermined) using the Ion Ampliseq Comprehensive Cancer Panel, which assesses copy number alterations and mutations in 409 cancer-relevant genes. Twelve tumors displayed prioritized high-level chromosomal gains or losses (average 1.9 per tumor). Non-synonymous high-confidence somatic mutations were detected in 14 tumors (average 11.9 per tumor). Assessing all somatic coding mutations, an ultraviolet-signature mutational profile was present, and more prevalent in Merkel cell polyomavirus-negative tumors. Recurrent deleterious tumor suppressor mutations affected TP53 (9/15, 60%), RB1 (3/15, 20%), and BAP1 (2/15, 13%). Oncogenic activating mutations included PIK3CA (3/15, 20%), AKT1 (1/15, 7%) and EZH2 (1/15, 7%). In conclusion, CK20-negative Merkel cell carcinoma display overlapping genetic changes

Next Generation Sequencing of Cytokeratin 20-Negative Merkel Cell Carcinoma Reveals Ultraviolet Signature Mutations and Recurrent TP53 and RB1 Inactivation

Science.gov (United States)

Harms, Paul W.; Collie, Angela M. B.; Hovelson, Daniel H.; Cani, Andi K.; Verhaegen, Monique E.; Patel, Rajiv M.; Fullen, Douglas R.; Omata, Kei; Dlugosz, Andrzej A.; Tomlins, Scott A.; Billings, Steven D.

2016-01-01

Merkel cell carcinoma is a rare but highly aggressive cutaneous neuroendocrine carcinoma. Cytokeratin-20 (CK20) is expressed in approximately 95% of Merkel cell carcinomas and is useful for distinction from morphologically similar entities including metastatic small cell lung carcinoma. Lack of CK20 expression may make diagnosis of Merkel cell carcinoma more challenging, and has unknown biological significance. Approximately 80% of CK20-positive Merkel cell carcinomas are associated with the oncogenic Merkel cell polyomavirus. Merkel cell carcinomas lacking Merkel cell polyomavirus display distinct genetic changes from Merkel cell polyomavirus-positive Merkel cell carcinoma, including RB1 inactivating mutations. Unlike CK20-positive Merkel cell carcinoma, the majority of CK20-negative Merkel cell carcinomas are Merkel cell polyomavirus-negative, suggesting CK20-negative Merkel cell carcinomas predominantly arise through virus-independent pathway(s) and may harbor additional genetic differences from conventional Merkel cell carcinoma. Hence, we analyzed 15 CK20-negative Merkel cell carcinoma tumors (ten Merkel cell polyomavirus-negative, four Merkel cell polyomavirus-positive, and one undetermined) using the Ion Ampliseq Comprehensive Cancer Panel, which assesses copy number alterations and mutations in 409 cancer-relevant genes. Twelve tumors displayed prioritized high-level chromosomal gains or losses (average 1.9 per tumor). Non-synonymous high confidence somatic mutations were detected in 14 tumors (average 11.9 per tumor). Assessing all somatic coding mutations, an ultraviolet-signature mutational profile was present, and more prevalent in Merkel cell polyomavirus-negative tumors. Recurrent deleterious tumor suppressor mutations affected TP53 (9/15, 60%), RB1 (3/15, 20%), and BAP1 (2/15, 13%). Oncogenic activating mutations included PIK3CA (3/15, 20%), AKT1 (1/15, 7%)) and EZH2 (1/15, 7%). In conclusion, CK20-negative Merkel cell carcinoma display overlapping

Potential role of TRIM3 as a novel tumour suppressor in colorectal cancer (CRC) development.

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Piao, Mei-Yu; Cao, Hai-Long; He, Na-Na; Xu, Meng-Que; Dong, Wen-Xiao; Wang, Wei-Qiang; Wang, Bang-Mao; Zhou, Bing

2016-01-01

Colorectal cancer (CRC) is the third leading cause of cancer-related mortality in the United States. Recent cancer genome-sequencing efforts and complementary functional studies have led to the identification of a collection of candidate 'driver' genes involved in CRC tumorigenesis. Tripartite motif (TRIM3) is recently identified as a tumour suppressor in glioblastoma but this tumour-suppressive function has not been investigated in CRC. In this study, we investigated the potential role of TRIM3 as a tumour suppressor in CRC development by manipulating the expression of TRIM3 in two authentic CRC cell lines, HCT116 and DLD1, followed by various functional assays, including cell proliferation, colony formation, scratch wound healing, soft agar, and invasion assays. Xenograft experiment was performed to examine in vivo tumour-suppressive properties of TRIM3. Small-interfering RNA (siRNA) mediated knockdown of TRIM3 conferred growth advantage in CRC cells. In contrast, overexpression of TRIM3 affected cell survival, cell migration, anchorage independent growth and invasive potential in CRC cells. In addition, TRIM3 was found to be down-regulated in human colon cancer tissues compared with matched normal colon tissues. Overexpression of TRIM3 significantly inhibited tumour growth in vivo using xenograft mouse models. Mechanistic investigation revealed that TRIM3 can regulate p53 protein level through its stabilisation. TRIM3 functions as a tumour suppressor in CRC progression. This tumour-suppressive function is exerted partially through regulation of p53 protein. Therefore, this protein may represent a novel therapeutic target for prevention or intervention of CRC.

Genetic alterations in head and neck squamous cell carcinomas

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Nagai M.A.

1999-01-01

Full Text Available The genetic alterations observed in head and neck cancer are mainly due to oncogene activation (gain of function mutations and tumor suppressor gene inactivation (loss of function mutations, leading to deregulation of cell proliferation and death. These genetic alterations include gene amplification and overexpression of oncogenes such as myc, erbB-2, EGFR and cyclinD1 and mutations, deletions and hypermethylation leading to p16 and TP53 tumor suppressor gene inactivation. In addition, loss of heterozygosity in several chromosomal regions is frequently observed, suggesting that other tumor suppressor genes not yet identified could be involved in the tumorigenic process of head and neck cancers. The exact temporal sequence of the genetic alterations during head and neck squamous cell carcinoma (HNSCC development and progression has not yet been defined and their diagnostic or prognostic significance is controversial. Advances in the understanding of the molecular basis of head and neck cancer should help in the identification of new markers that could be used for the diagnosis, prognosis and treatment of the disease.

Distribution of mutations in the PEX gene in families with X-linked hypophosphataemic rickets (HYP).

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Rowe, P S; Oudet, C L; Francis, F; Sinding, C; Pannetier, S; Econs, M J; Strom, T M; Meitinger, T; Garabedian, M; David, A; Macher, M A; Questiaux, E; Popowska, E; Pronicka, E; Read, A P; Mokrzycki, A; Glorieux, F H; Drezner, M K; Hanauer, A; Lehrach, H; Goulding, J N; O'Riordan, J L

1997-04-01

Mutations in the PEX gene at Xp22.1 (phosphate-regulating gene with homologies to endopeptidases, on the X-chromosome), are responsible for X-linked hypophosphataemic rickets (HYP). Homology of PEX to the M13 family of Zn2+ metallopeptidases which include neprilysin (NEP) as prototype, has raised important questions regarding PEX function at the molecular level. The aim of this study was to analyse 99 HYP families for PEX gene mutations, and to correlate predicted changes in the protein structure with Zn2+ metallopeptidase gene function. Primers flanking 22 characterised exons were used to amplify DNA by PCR, and SSCP was then used to screen for mutations. Deletions, insertions, nonsense mutations, stop codons and splice mutations occurred in 83% of families screened for in all 22 exons, and 51% of a separate set of families screened in 17 PEX gene exons. Missense mutations in four regions of the gene were informative regarding function, with one mutation in the Zn2+-binding site predicted to alter substrate enzyme interaction and catalysis. Computer analysis of the remaining mutations predicted changes in secondary structure, N-glycosylation, protein phosphorylation and catalytic site molecular structure. The wide range of mutations that align with regions required for protease activity in NEP suggests that PEX also functions as a protease, and may act by processing factor(s) involved in bone mineral metabolism.

Effects of atomic bomb radiation on differentiation of B lymphocytes and on the function of concanavalin A-induced suppressor T lymphocytes

International Nuclear Information System (INIS)

Yamada, Y.; Neriishi, S.; Ishimaru, T.; Shimba, N.; Hamilton, H.B.; Ohgushi, Y.; Koyanagi, M.; Ichimaru, M.

1985-01-01

The differentiation of peripheral blood B lymphocytes into immunoglobulin-producing cells (Ig-PC) by pokeweed mitogen (PWM) and the function of concanavalin A (Con A)-induced suppressor T lymphocytes were examined to elucidate the late effects of atomic bomb radiation. A total of 140 individuals, 70 with an exposure dose of 100 rad or more and an equal number with an exposure dose of 0 rad matched by sex and age, were selected from the Nagasaki Adult Health Study (AHS) sample. Both the differentiation of peripheral blood B lymphocytes into Ig-PC by PWM and the function of Con A-induced suppressor T lymphocytes tended to be more depressed in the exposed group than in the control group, but a statistically significant difference could not be observed between the two groups. The function of Con A-induced suppressor T lymphocytes tended to decrease with age, but a statistical significance was detected only for percentage suppression against IgM-PC

Causation of nervous system tumors in children: insights from traditional and genetically engineered animal models

International Nuclear Information System (INIS)

Rice, Jerry M.

2004-01-01

Pediatric neurogenic tumors include primitive neuroectodermal tumors (PNETs), especially medulloblastoma; ependymomas and choroid plexus papillomas; astrocytomas; retinoblastoma; and sympathetic neuroblastoma. Meningiomas and nerve sheath tumors, although uncommon in childhood, are also significant because they can result from exposures of children to ionizing radiation. Specific chromosomal loci and specific genes are related to each of these tumor types. Virtually all these genes appear to act as tumor suppressor genes, which are inactivated in tumor cells by mutations or by chromosomal loss. In genetically engineered mice, some genes that are clearly associated with specific human tumors (e.g., RB1 in retinoblastoma and NF2 in meningiomas and schwannomas) have no such effect. Other genetic constructs in mice involving the genes p53, ptc1, and Nf1 have produced tumors remarkably similar to some of the human pediatric neoplasms. Some of these tumors become clinically apparent after only a few weeks, while the mice are still juveniles, especially when two or more tumor suppressor genes are inactivated in the same genetic construct. Conversely, at least one genetic pathway in rodents involving point mutation in the coding region of a transforming gene (neu in malignant schwannomas) does not appear to operate in any human tumors. The nervous system is markedly susceptible to experimental carcinogenesis during early life in rodents, dogs, primates, and other nonhuman species, and there is no obvious reason why this generalization should not also apply to humans. However, except for therapeutic ionizing radiation, no physical, chemical, or biological cause of human pediatric nervous system tumors is known. The failure of experimental transplacental carcinogenesis to mirror human pediatric experience more closely may reflect the need for multiple mutational events in target cells, and for experimental carcinogens that are capable of causing the full spectrum of

Mutation Spectrum and Phenotypic Features in Noonan Syndrome with PTPN11 Mutations: Definition of Two Novel Mutations.

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Atik, Tahir; Aykut, Ayca; Hazan, Filiz; Onay, Huseyin; Goksen, Damla; Darcan, Sukran; Tukun, Ajlan; Ozkinay, Ferda

2016-06-01

To evaluate the spectrum of PTPN11 gene mutations in Noonan syndrome patients and to study the genotype-phenotype associations. In this study, twenty Noonan syndrome patients with PTPN11 mutations were included. The patients underwent a detailed clinical and physical evaluation. To identify inherited cases, parents of all mutation positive patients were analyzed. Thirteen different PTPN11 mutations, two of them being novel, were detected in the study group. These mutations included eleven missense mutations: p.G60A, p.D61N, p.Y62D, p.Y63C, p.E69Q, p.Q79R, p.Y279C,p.N308D, p.N308S, p.M504V, p.Q510R and two novel missense mutations: p.I56V and p.I282M. The frequency of cardiac abnormalities and short stature were found to be 80 % and 80 %, respectively. Mental retardation was not observed in patients having exon 8 mutations. No significant correlations were detected between other phenotypic features and genotypes. By identifying genotype-phenotype correlations, this study provides information on phenotypes observed in NS patients with different PTPN11 mutations.

The Luteovirus P4 Movement Protein Is a Suppressor of Systemic RNA Silencing.

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Fusaro, Adriana F; Barton, Deborah A; Nakasugi, Kenlee; Jackson, Craig; Kalischuk, Melanie L; Kawchuk, Lawrence M; Vaslin, Maite F S; Correa, Regis L; Waterhouse, Peter M

2017-10-10

The plant viral family Luteoviridae is divided into three genera: Luteovirus , Polerovirus and Enamovirus . Without assistance from another virus, members of the family are confined to the cells of the host plant's vascular system. The first open reading frame (ORF) of poleroviruses and enamoviruses encodes P0 proteins which act as silencing suppressor proteins (VSRs) against the plant's viral defense-mediating RNA silencing machinery. Luteoviruses, such as barley yellow dwarf virus-PAV (BYDV-PAV), however, have no P0 to carry out the VSR role, so we investigated whether other proteins or RNAs encoded by BYDV-PAV confer protection against the plant's silencing machinery. Deep-sequencing of small RNAs from plants infected with BYDV-PAV revealed that the virus is subjected to RNA silencing in the phloem tissues and there was no evidence of protection afforded by a possible decoy effect of the highly abundant subgenomic RNA3. However, analysis of VSR activity among the BYDV-PAV ORFs revealed systemic silencing suppression by the P4 movement protein, and a similar, but weaker, activity by P6. The closely related BYDV-PAS P4, but not the polerovirus potato leafroll virus P4, also displayed systemic VSR activity. Both luteovirus and the polerovirus P4 proteins also showed transient, weak local silencing suppression. This suggests that systemic silencing suppression is the principal mechanism by which the luteoviruses BYDV-PAV and BYDV-PAS minimize the effects of the plant's anti-viral defense.

Induction of CD4 suppressor T cells with anti-Leu-8 antibody

International Nuclear Information System (INIS)

Kanof, M.E.; Strober, W.; James, S.P.

1987-01-01

To characterize the conditions under which CD4 T cells suppress polyclonal immunoglobulin synthesis, we investigated the capacity of CD4 T cells that coexpress the surface antigen recognized by the monoclonal antibody anti-Leu-8 to mediate suppression. In an in vitro system devoid of CD8 T cells, CD4, Leu-8+ T cells suppressed pokeweed mitogen-induced immunoglobulin synthesis. Similarly, suppressor function was induced in unfractionated CD4 T cell populations after incubation with anti-Leu-8 antibody under cross-linking conditions. This induction of suppressor function by anti-Leu-8 antibody was not due to expansion of the CD4, Leu-8+ T cell population because CD4 T cells did not proliferate in response to anti-Leu-8 antibody. However, CD4, Leu-8+ T cell-mediated suppression was radiosensitive. Finally, CD4, Leu-8+ T cells do not inhibit immunoglobulin synthesis when T cell lymphokines were used in place of helper CD4 T cells (CD4, Leu-8- T cells), suggesting that CD4 T cell-mediated suppression occurs at the T cell level. We conclude that CD4 T cells can be induced to suppress immunoglobulin synthesis by modulation of the membrane antigen recognized by anti-Leu-8 antibody

Analysis of 6174delT Mutation in BRCA2 Gene by Mutagenically Separated PCR Among Libyan Patients with Breast Cancer

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Lamia Elfandi

2016-03-01

Full Text Available Background: Breast cancer is the most common malignancy among women. It is estimated that 1 in 10 women worldwide is affected by breast cancer during their lifetime. In 5 to 10% of breast cancer patients, the disease results from a hereditary predisposition, which can be attributable to mutations in either of two tumor suppressor genes, BRCA1 and BRCA2 to a large extent. BRCA2 6174delT mutation constitutes the common mutant alleles which predispose to hereditary breast cancer in the Ashkenazi population with a reported carrier frequency of 1.52%. In this study, we investigated the presence of the 6174delT mutation of the BRCA2 gene in Libyan woman affected with breast cancer and compared the results with those of other population groups.Methods: Eighty- five Libyan women with breast cancer in additions to 5 relatives of the patients (healthy individuals were recruited to this study. We obtained clinical information, family history, and peripheral blood for DNA extraction and analyzed the data using multiplex mutagenic polymerase chain reaction (MS-PCR for detection of 6174delT mutation in the BRCA2 gene. Results: The 6174delT of the BRCA2 gene was not detected either in the 85 patients with breast cancer (18 with familial breast cancer and 67 with sporadic breast cancer nor in the 5 healthy individuals. Conclusions: The present study showed that the 6174delT of the BRCA2 gene was not detectable using mutagenic PCR in the Libyan patients with breast cancer and can be considered to be exceedingly rare