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Sample records for c-myc mrna stability

  1. Cadmium Activates Multiple Signaling Pathways That Coordinately Stimulate Akt Activity to Enhance c-Myc mRNA Stability.

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    Jia-Shiuan Tsai

    Full Text Available Cadmium is a known environmental carcinogen. Exposure of Cd leads to the activation of several proto-oncogenes in cells. We investigated here the mechanism of c-Myc expression in hepatic cells under Cd treatment. The c-Myc protein and mRNA levels increased in dose- and time-dependent manners in HepG2 cells with Cd treatment. This increase was due to an increase in c-Myc mRNA stability. To explore the mechanism involved in enhancing the mRNA stability, several cellular signaling factors that evoked by Cd treatment were analyzed. PI3K, p38, ERK and JNK were activated by Cd. However, ERK did not participate in the Cd-induced c-Myc expression. Further analysis revealed that mTORC2 was a downstream factor of p38. PI3K, JNK and mTORC2 coordinately activated Akt. Akt was phosphorylated at Thr450 in the untreated cells. Cd treatment led to additional phosphorylation at Thr308 and Ser473. Blocking any of the three signaling factors resulted in the reduction of phosphorylation level at all three Akt sites. The activated Akt phosphorylated Foxo1 and allowed the modified protein to translocate into the cytoplasm. We conclude that Cd-induced accumulation of c-Myc requires the activation of several signaling pathways. The signals act coordinately for Akt activation and drive the Foxo1 from the nucleus to the cytoplasm. Reduction of Foxo1 in the nucleus reduces the transcription of its target genes that may affect c-Myc mRNA stability, resulting in a higher accumulation of the c-Myc proteins.

  2. Long non-coding RNA GHET1 promotes gastric carcinoma cell proliferation by increasing c-Myc mRNA stability.

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    Yang, Feng; Xue, Xuchao; Zheng, Luming; Bi, Jianwei; Zhou, Yuhong; Zhi, Kangkang; Gu, Yan; Fang, Guoen

    2014-02-01

    Long non-coding RNAs (lncRNAs), a recently characterized class of non-coding RNAs, have been shown to have important regulatory roles and are de-regulated in a variety of tumors. However, the contributions of lncRNAs to gastric carcinoma and their functional mechanisms remain largely unknown. In this study, we found that lncRNA gastric carcinoma high expressed transcript 1 (lncRNA-GHET1) was up-regulated in gastric carcinoma. The over-expression of this lncRNA correlates with tumor size, tumor invasion and poor survival. Gain-of-function and loss-of-function analyses demonstrated that GHET1 over-expression promotes the proliferation of gastric carcinoma cells in vitro and in vivo. Knockdown of GHET1 inhibits the proliferation of gastric carcinoma cells. RNA pull-down and immunoprecipitation assays confirmed that GHET1 physically associates with insulin-like growth factor 2 mRNA binding protein 1 (IGF2BP1) and enhances the physical interaction between c-Myc mRNA and IGF2BP1, consequently increasing the stability of c-Myc mRNA and expression. The expression of GHET1 and c-Myc is strongly correlated in gastric carcinoma tissues. Depletion of c-Myc abolishes the effects of GHET1 on proliferation of gastric carcinoma cells. Taken together, these findings indicate that GHET1 plays a pivotal role in gastric carcinoma cell proliferation via increasing c-Myc mRNA stability and expression, which suggests potential use of GHET1 for the prognosis and treatment of gastric carcinoma. © 2013 FEBS.

  3. c-Myc deregulation induces mRNA capping enzyme dependency

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    Lombardi, Olivia; Varshney, Dhaval; Phillips, Nicola M.; Cowling, Victoria H.

    2016-01-01

    c-Myc is a potent driver of many human cancers. Since strategies for directly targeting c-Myc protein have had limited success, upstream regulators and downstream effectors of c-Myc are being investigated as alternatives for therapeutic intervention. c-Myc regulates transcription and formation of the mRNA cap, which is important for transcript maturation and translation. However, the direct mechanism by which c-Myc upregulates mRNA capping is unclear. mRNA cap formation initiates with the linkage of inverted guanosine via a triphosphate bridge to the first transcribed nucleotide, catalysed by mRNA capping enzyme (CE/RNGTT). Here we report that c-Myc increases the recruitment of catalytically active CE to RNA polymerase II and to its target genes. c-Myc-induced target gene expression, cell proliferation and cell transformation is highly dependent on CE, but only when c-Myc is deregulated. Cells retaining normal control of c-Myc expression are insensitive to repression of CE. c-Myc expression is also dependent on CE. Therefore, inhibiting CE provides an attractive route for selective therapeutic targeting of cancer cells which have acquired deregulated c-Myc. PMID:27756891

  4. c-Myc deregulation induces mRNA capping enzyme dependency.

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    Lombardi, Olivia; Varshney, Dhaval; Phillips, Nicola M; Cowling, Victoria H

    2016-12-13

    c-Myc is a potent driver of many human cancers. Since strategies for directly targeting c-Myc protein have had limited success, upstream regulators and downstream effectors of c-Myc are being investigated as alternatives for therapeutic intervention. c-Myc regulates transcription and formation of the mRNA cap, which is important for transcript maturation and translation. However, the direct mechanism by which c-Myc upregulates mRNA capping is unclear. mRNA cap formation initiates with the linkage of inverted guanosine via a triphosphate bridge to the first transcribed nucleotide, catalysed by mRNA capping enzyme (CE/RNGTT). Here we report that c-Myc increases the recruitment of catalytically active CE to RNA polymerase II and to its target genes. c-Myc-induced target gene expression, cell proliferation and cell transformation is highly dependent on CE, but only when c-Myc is deregulated. Cells retaining normal control of c-Myc expression are insensitive to repression of CE. c-Myc expression is also dependent on CE. Therefore, inhibiting CE provides an attractive route for selective therapeutic targeting of cancer cells which have acquired deregulated c-Myc.

  5. Modulation of Radio-response by the Modification and Stabilization of c-Myc by IKK{gamma}

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    Kim, Bu Yeon; Han, Young Hoon [Korea Institute of Radiological and Medical Sciences, Seoul (Korea, Republic of)

    2009-05-15

    The transcription factor c-Myc plays a critical role in multiple cellular processes including cell cycle progression, proliferation, differentiation, and apoptosis. The expression of c-Myc is generally upregulated in most of human cancers during tumor progression. Correct regulation of c-Myc accumulation is thus essential, and achieved by multiple mechanisms acting at different stages of protein expression including the regulation of transcription, mRNA stability, translation, and protein stability. Various mechanisms have been reported to regulate the stability of c-Myc. IKK{gamma} is a critical component for the activity of IKK complex, which is essential for NF-{kappa}B activation in response to a variety of stress stimuli. Besides the cytoplasmic role of IKK{gamma} in regulating the activity of IKK complex, IKK{gamma} was shown to shuttle between cytoplasm and nucleus and play a nuclear role in transcriptional repression of the NF-{kappa}B pathway. Here, we report that IKK{gamma} stabilizes c-Myc protein through direct interaction and the stabilization and possible modification of c-Myc by IKK{gamma} modulates the cellular response to ionizing radiation.

  6. The nucleolar ubiquitin-specific protease USP36 deubiquitinates and stabilizes c-Myc

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    Sun, Xiao-Xin; He, Xia; Yin, Li; Komada, Masayuki; Sears, Rosalie C.; Dai, Mu-Shui

    2015-01-01

    c-Myc protein stability and activity are tightly regulated by the ubiquitin-proteasome system. Aberrant stabilization of c-Myc contributes to many human cancers. c-Myc is ubiquitinated by SCFFbw7 (a SKP1-cullin-1-F-box complex that contains the F-box and WD repeat domain-containing 7, Fbw7, as the F-box protein) and several other ubiquitin ligases, whereas it is deubiquitinated and stabilized by ubiquitin-specific protease (USP) 28. The bulk of c-Myc degradation appears to occur in the nucleolus. However, whether c-Myc is regulated by deubiquitination in the nucleolus is not known. Here, we report that the nucleolar deubiquitinating enzyme USP36 is a novel c-Myc deubiquitinase. USP36 interacts with and deubiquitinates c-Myc in cells and in vitro, leading to the stabilization of c-Myc. This USP36 regulation of c-Myc occurs in the nucleolus. Interestingly, USP36 interacts with the nucleolar Fbw7γ but not the nucleoplasmic Fbw7α. However, it abolished c-Myc degradation mediated both by Fbw7γ and by Fbw7α. Consistently, knockdown of USP36 reduces the levels of c-Myc and suppresses cell proliferation. We further show that USP36 itself is a c-Myc target gene, suggesting that USP36 and c-Myc form a positive feedback regulatory loop. High expression levels of USP36 are found in a subset of human breast and lung cancers. Altogether, these results identified USP36 as a crucial and bono fide deubiquitinating enzyme controlling c-Myc’s nucleolar degradation pathway. PMID:25775507

  7. c-Myc co-ordinates mRNA cap methylation and ribosomal RNA production.

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    Dunn, Sianadh; Lombardi, Olivia; Cowling, Victoria H

    2017-02-01

    The mRNA cap is a structure added to RNA pol II transcripts in eukaryotes, which recruits factors involved in RNA processing, nuclear export and translation initiation. RNA guanine-7 methyltransferase (RNMT)-RNA-activating miniprotein (RAM), the mRNA cap methyltransferase complex, completes the basic functional mRNA cap structure, cap 0, by methylating the cap guanosine. Here, we report that RNMT-RAM co-ordinates mRNA processing with ribosome production. Suppression of RNMT-RAM reduces synthesis of the 45S ribosomal RNA (rRNA) precursor. RNMT-RAM is required for c-Myc expression, a major regulator of RNA pol I, which synthesises 45S rRNA. Constitutive expression of c-Myc restores rRNA synthesis when RNMT-RAM is suppressed, indicating that RNMT-RAM controls rRNA production predominantly by controlling c-Myc expression. We report that RNMT-RAM is recruited to the ribosomal DNA locus, which may contribute to rRNA synthesis in certain contexts. © 2017 The Author(s).

  8. c-myc mRNA in cytoskeletal-bound polysomes in fibroblasts.

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    Hesketh, J E; Campbell, G P; Whitelaw, P F

    1991-03-01

    3T3 fibroblasts were treated sequentially with 25 mM-KCl/0.05% Nonidet P40, 130 mM-KCl/0.05% Nonidet P40 and finally with 1% Nonidet P40/1% deoxycholate in order to release free, cytoskeletal-bound and membrane-bound polysomes respectively. The membrane-bound fraction was enriched in the mRNA for the membrane protein beta 2-microglobulin, whereas the cytoskeletal-bound polysomes were enriched in c-myc mRNA. Actin mRNA was present in both free and cytoskeletal-bound polysomes. The results suggest that cytoskeletal-bound polysomes are involved in the translation of specific mRNA species.

  9. Specific regulation of mRNA cap methylation by the c-Myc and E2F1 transcription factors

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    Cole, Michael D.; Cowling, Victoria H.

    2009-01-01

    Methylation of the mRNA 5′ guanosine cap is essential for efficient gene expression. The 5′methyl cap binds to eIF4E, which is the first step in the recruitment of mRNA to the 40S ribosomal subunit. To investigate whether mRNA cap methylation is regulated in a gene-specific manner, we established a method to detect the relative level of cap methylation on specific mRNAs. We found that two transcription factors, c-Myc and E2F1, induce cap methylation of their transcriptional target genes, and therefore, c-Myc and E2F1 upregulate gene expression by simultaneously inducing transcription and promoting translation. c-Myc-induced cap methylation is greater than transcriptional induction for the majority of its target genes, indicating that this is a major mechanism by which Myc regulates gene expression. PMID:19137018

  10. Systematic analysis of the contribution of c-myc mRNA constituents upon cap and IRES mediated translation.

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    Meristoudis, Christos; Trangas, Theoni; Lambrianidou, Andromachi; Papadopoulos, Vasilios; Dimitriadis, Euthymios; Courtis, Nelly; Ioannidis, Panayotis

    2015-12-01

    Fine tuning of c-MYC expression is critical for its action and is achieved by several regulatory mechanisms. The contribution of c-myc mRNA regulatory sequences on its translational control has been investigated individually. However, putative interactions have not been addressed so far. The effect of these interactions upon the translatability of monocistronic and bicistronic chimaeric mRNAs, carrying combinations of the c-myc mRNA 5'-untranlated region (UTR), 3'-UTR, and coding region instability element (CRD) was investigated on this study. The presence of the 5'-UTR induced an increase in translatability of 50%. The presence of the CRD element, when in frame, reduced translatability by approximately 50%, regardless of the expression levels of the wild type CRD- binding protein (CRD-BP/IMP1). Conversely, overexpression of a mutated CRD-BP/IMP1 (Y396F) further impeded translation of the chimaeric mRNAs carrying its cognate sequences. The presence of the c-myc 3'-UTR increased translatability by approximately 300% affecting both cap and c-myc internal ribosome entry site (IRES) mediated translation. In addition, 3'-UTR rescued the cap mediated translation in the presence of the polyadenylation inhibitor cordycepin. Furthermore, the 3'-UTR rescued cap mediated translation under metabolic stress conditions and this was enhanced in the absence of a long poly (A) tail.

  11. Microcystin-LR stabilizes c-myc protein by inhibiting protein phosphatase 2A in HEK293 cells.

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    Fan, Huihui; Cai, Yan; Xie, Ping; Xiao, Wuhan; Chen, Jun; Ji, Wei; Zhao, Sujuan

    2014-05-07

    Microcystin-LR is the most toxic and the most frequently encountered toxin produced by the cyanobacteria in the contaminated aquatic environment. Previous studies have demonstrated that Microcystin-LR is a potential carcinogen for animals and humans, and the International Agency for Research on Cancer has classified Microcystin-LR as a possible human carcinogen. However, the precise molecular mechanisms of Microcystin-LR-induced carcinogenesis remain a mystery. C-myc is a proto-oncogene, abnormal expression of which contributes to the tumor development. Although several studies have demonstrated that Microcystin-LR could induce c-myc expression at the transcriptional level, the exact connection between Microcystin-LR toxicity and c-myc response remains unclear. In this study, we showed that the c-myc protein increased in HEK293 cells after exposure to Microcystin-LR. Coexpression of protein phosphatase 2A and two stable c-myc protein point mutants (either c-myc(T58A) or c-myc(S62A)) showed that Microcystin-LR increased c-myc protein level mainly through inhibiting protein phosphatase 2A activity which altered the phosphorylation status of serine 62 on c-myc. In addition, we also showed that Microcystin-LR could increase c-myc promoter activity as revealed by luciferase reporter assay. And the TATA box for P1 promoter of c-myc might be involved. Our results suggested that Microcystin-LR can stimulate c-myc transcription and stabilize c-myc protein, which might contribute to hepatic tumorigenesis in animals and humans.

  12. c-Myc affects mRNA translation, cell proliferation and progenitor cell function in the mammary gland

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    Trumpp Andreas

    2009-09-01

    Full Text Available Abstract Background The oncoprotein c-Myc has been intensely studied in breast cancer and mouse mammary tumor models, but relatively little is known about the normal physiological role of c-Myc in the mammary gland. Here we investigated functions of c-Myc during mouse mammary gland development using a conditional knockout approach. Results Generation of c-mycfl/fl mice carrying the mammary gland-specific WAPiCre transgene resulted in c-Myc loss in alveolar epithelial cells starting in mid-pregnancy. Three major phenotypes were observed in glands of mutant mice. First, c-Myc-deficient alveolar cells had a slower proliferative response at the start of pregnancy, causing a delay but not a block of alveolar development. Second, while milk composition was comparable between wild type and mutant animals, milk production was reduced in mutant glands, leading to slower pup weight-gain. Electron microscopy and polysome fractionation revealed a general decrease in translational efficiency. Furthermore, analysis of mRNA distribution along the polysome gradient demonstrated that this effect was specific for mRNAs whose protein products are involved in milk synthesis. Moreover, quantitative reverse transcription-polymerase chain reaction analysis revealed decreased levels of ribosomal RNAs and ribosomal protein-encoding mRNAs in mutant glands. Third, using the mammary transplantation technique to functionally identify alveolar progenitor cells, we observed that the mutant epithelium has a reduced ability to repopulate the gland when transplanted into NOD/SCID recipients. Conclusion We have demonstrated that c-Myc plays multiple roles in the mouse mammary gland during pregnancy and lactation. c-Myc loss delayed, but did not block proliferation and differentiation in pregnancy. During lactation, lower levels of ribosomal RNAs and proteins were present and translation was generally decreased in mutant glands. Finally, the transplantation studies suggest a role

  13. Deubiquitinating enzyme USP22 positively regulates c-Myc stability and tumorigenic activity in mammalian and breast cancer cells.

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    Kim, Dongyeon; Hong, Ahyoung; Park, Hye In; Shin, Woo Hyun; Yoo, Lang; Jeon, Seo Jeong; Chung, Kwang Chul

    2017-12-01

    The proto-oncogene c-Myc has a pivotal function in growth control, differentiation, and apoptosis and is frequently affected in human cancer, including breast cancer. Ubiquitin-specific protease 22 (USP22), a member of the USP family of deubiquitinating enzymes (DUBs), mediates deubiquitination of target proteins, including histone H2B and H2A, telomeric repeat binding factor 1, and cyclin B1. USP22 is also a component of the mammalian SAGA transcriptional co-activating complex. In this study, we explored the functional role of USP22 in modulating c-Myc stability and its physiological relevance in breast cancer progression. We found that USP22 promotes deubiquitination of c-Myc in several breast cancer cell lines, resulting in increased levels of c-Myc. Consistent with this, USP22 knockdown reduces c-Myc levels. Furthermore, overexpression of USP22 stimulates breast cancer cell growth and colony formation, and increases c-Myc tumorigenic activity. In conclusion, the present study reveals that USP22 in breast cancer cell lines increases c-Myc stability through c-Myc deubiquitination, which is closely correlated with breast cancer progression. © 2017 Wiley Periodicals, Inc.

  14. Ruthenium(II) complexes as apoptosis inducers by stabilizing c-myc G-quadruplex DNA.

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    Zhang, Zhao; Wu, Qiong; Wu, Xiao-Hui; Sun, Fen-Yong; Chen, Lan-Mei; Chen, Jin-Chan; Yang, Shu-Ling; Mei, Wen-Jie

    2014-06-10

    Two ruthenium(II) complexes, [Ru(L)2(p-tFMPIP)](ClO4)2 (L = bpy, 1; phen, 2; p-tFMPIP = 2-(4-(trifluoromethyphenyl)-1H-imidazo[4,5f][1,10] phenanthroline)), were prepared by microwave-assisted synthesis technology. The inhibitory activity evaluated by MTT assay shown that 2 can inhibit the growth of MDA-MB-231 cells with inhibitory activity (IC50) of 16.3 μM, which was related to the induction of apoptosis. Besides, 2 exhibit low toxicity against normal HAcat cells. The inhibitory growth activity of both complexes related to the induction of apoptosis was also confirmed. Furthermore, the studies on the interaction of both complexes with c-myc G4 DNA shown that 1 and 2 can stabilize the conformation of c-myc G4 DNA in groove binding mode, which has been rational explained by using DFT theoretical calculation methods. In a word, this type of ruthenium(II) complexes can act as potential apoptosis inducers with low toxicity in clinic by stabilizing c-myc G4 DNA.

  15. O-GlcNAc transferase integrates metabolic pathways to regulate the stability of c-MYC in human prostate cancer cells.

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    Itkonen, Harri M; Minner, Sarah; Guldvik, Ingrid J; Sandmann, Mareike Julia; Tsourlakis, Maria Christina; Berge, Viktor; Svindland, Aud; Schlomm, Thorsten; Mills, Ian G

    2013-08-15

    Metabolic disruptions that occur widely in cancers offer an attractive focus for generalized treatment strategies. The hexosamine biosynthetic pathway (HBP) senses metabolic status and produces an essential substrate for O-linked β-N-acetylglucosamine transferase (OGT), which glycosylates and thereby modulates the function of its target proteins. Here, we report that the HBP is activated in prostate cancer cells and that OGT is a central regulator of c-Myc stability in this setting. HBP genes were overexpressed in human prostate cancers and androgen regulated in cultured human cancer cell lines. Immunohistochemical analysis of human specimens (n = 1987) established that OGT is upregulated at the protein level and that its expression correlates with high Gleason score, pT and pN stages, and biochemical recurrence. RNA interference-mediated siliencing or pharmacologic inhibition of OGT was sufficient to decrease prostate cancer cell growth. Microarray profiling showed that the principal effects of OGT inhibition in prostate cancer cells were related to cell-cycle progression and DNA replication. In particular, c-MYC was identified as a candidate upstream regulator of OGT target genes and OGT inhibition elicited a dose-dependent decrease in the levels of c-MYC protein but not c-MYC mRNA in cell lines. Supporting this relationship, expression of c-MYC and OGT was tightly correlated in human prostate cancer samples (n = 1306). Our findings identify HBP as a modulator of prostate cancer growth and c-MYC as a key target of OGT function in prostate cancer cells.

  16. Regulation of c-Myc mRNA by L11 in Response to UV and Gamma Irradiation

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    2014-12-01

    cleared cell lysates were immunoprecipitated using anti-c-Myc (C33; Santa Cruz Biotechnology ) mono- clonal antibody-conjugated beads. After washing, half...presence of protease inhibitors. Cell mem- branes were then broken using a Dounce homogenizer (tight pestle) and 10 up-and-down strokes . After centrifugation

  17. Assessment of the effect of betaine on p16 and c-myc DNA methylation and mRNA expression in a chemical induced rat liver cancer model

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    Ling Wen-hua

    2009-07-01

    Full Text Available Abstract Background The development and progression of liver cancer may involve abnormal changes in DNA methylation, which lead to the activation of certain proto-oncogenes, such as c-myc, as well as the inactivation of certain tumor suppressors, such as p16. Betaine, as an active methyl-donor, maintains normal DNA methylation patterns. However, there are few investigations on the protective effect of betaine in hepatocarcinogenesis. Methods Four groups of rats were given diethylinitrosamine (DEN and fed with AIN-93G diets supplemented with 0, 10, 20 or 40 g betaine/kg (model, 1%, 2%, and 4% betaine, respectively, while the control group, received no DEN, fed with AIN-93G diet. Eight or 15 weeks later, the expression of p16 and c-myc mRNA was examined by Real-time PCR (Q-PCR. The DNA methylation status within the p16 and c-myc promoter was analyzed using methylation-specific PCR. Results Compared with the model group, numbers and areas of glutathione S-transferase placental form (GST-p-positive foci were decreased in the livers of the rats treated with betaine (P . Although the frequency of p16 promoter methylation in livers of the four DEN-fed groups appeared to increase, there is no difference among these groups after 8 or 15 weeks (P > 0.05. Betaine supplementation attenuated the down-regulation of p16 and inhibited the up-regulation of c-myc induced by DEN in a dose-dependent manner (P P . Finally, enhanced antioxidative capacity (T-AOC was observed in both the 2% and 4% betaine groups. Conclusion Our data suggest that betaine attenuates DEN-induced damage in rat liver and reverses DEN-induced changes in mRNA levels.

  18. Ribosomal Protein L11 Recruits miR-24/miRISC To Repress c-Myc Expression in Response to Ribosomal Stress ▿

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    Challagundla, Kishore B.; Sun, Xiao-Xin; Zhang, Xiaoli; DeVine, Tiffany; Zhang, Qinghong; Sears, Rosalie C.; Dai, Mu-Shui

    2011-01-01

    c-Myc promotes cell growth by enhancing ribosomal biogenesis and translation. Deregulated expression of c-Myc and aberrant ribosomal biogenesis and translation contribute to tumorigenesis. Thus, a fine coordination between c-Myc and ribosomal biogenesis is vital for normal cell homeostasis. Here, we show that ribosomal protein L11 regulates c-myc mRNA turnover. L11 binds to c-myc mRNA at its 3′ untranslated region (3′-UTR), the core component of microRNA-induced silencing complex (miRISC) argonaute 2 (Ago2), as well as miR-24, leading to c-myc mRNA reduction. Knockdown of L11 drastically increases the levels and stability of c-myc mRNA. Ablation of Ago2 abrogated the L11-mediated reduction of c-myc mRNA, whereas knockdown of L11 rescued miR-24-mediated c-myc mRNA decay. Interestingly, treatment of cells with the ribosomal stress-inducing agent actinomycin D or 5-fluorouracil significantly decreased the c-myc mRNA levels in an L11- and Ago2-dependent manner. Both treatments enhanced the association of L11 with Ago2, miR-24, and c-myc mRNA. We further show that ribosome-free L11 binds to c-myc mRNA in the cytoplasm and that this binding is enhanced by actinomycin D treatment. Together, our results identify a novel regulatory paradigm wherein L11 plays a critical role in controlling c-myc mRNA turnover via recruiting miRISC in response to ribosomal stress. PMID:21807902

  19. USP10 Antagonizes c-Myc Transcriptional Activation through SIRT6 Stabilization to Suppress Tumor Formation

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    Zhenghong Lin

    2013-12-01

    Full Text Available The reduced protein expression of SIRT6 tumor suppressor is involved in tumorigenesis. The molecular mechanisms underlying SIRT6 protein downregulation in human cancers remain unknown. Using a proteomic approach, we have identified the ubiquitin-specific peptidase USP10, another tumor suppressor, as one of the SIRT6-interacting proteins. USP10 suppresses SIRT6 ubiquitination to protect SIRT6 from proteasomal degradation. USP10 antagonizes the transcriptional activity of the c-Myc oncogene through SIRT6, as well as p53, to inhibit cell-cycle progression, cancer cell growth, and tumor formation. To support this conclusion, we detected significant reductions in both USP10 and SIRT6 protein expression in human colon cancers. Our study discovered crosstalk between two tumor-suppressive genes in regulating cell-cycle progression and proliferation and showed that dysregulated USP10 function promotes tumorigenesis through SIRT6 degradation.

  20. Guttiferone K impedes cell cycle re-entry of quiescent prostate cancer cells via stabilization of FBXW7 and subsequent c-MYC degradation.

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    Xi, Z; Yao, M; Li, Y; Xie, C; Holst, J; Liu, T; Cai, S; Lao, Y; Tan, H; Xu, H-X; Dong, Q

    2016-06-02

    Cell cycle re-entry by quiescent cancer cells is an important mechanism for cancer progression. While high levels of c-MYC expression are sufficient for cell cycle re-entry, the modality to block c-MYC expression, and subsequent cell cycle re-entry, is limited. Using reversible quiescence rendered by serum withdrawal or contact inhibition in PTEN(null)/p53(WT) (LNCaP) or PTEN(null)/p53(mut) (PC-3) prostate cancer cells, we have identified a compound that is able to impede cell cycle re-entry through c-MYC. Guttiferone K (GUTK) blocked resumption of DNA synthesis and preserved the cell cycle phase characteristics of quiescent cells after release from the quiescence. In vehicle-treated cells, there was a rapid increase in c-MYC protein levels upon release from the quiescence. However, this increase was inhibited in the presence of GUTK with an associated acceleration in c-MYC protein degradation. The inhibitory effect of GUTK on cell cycle re-entry was significantly reduced in cells overexpressing c-MYC. The protein level of FBXW7, a subunit of E3 ubiquitin ligase responsible for degradation of c-MYC, was reduced upon the release from the quiescence. In contrast, GUTK stabilized FBXW7 protein levels during release from the quiescence. The critical role of FBXW7 was confirmed using siRNA knockdown, which impaired the inhibitory effect of GUTK on c-MYC protein levels and cell cycle re-entry. Administration of GUTK, either in vitro prior to transplantation or in vivo, suppressed the growth of quiescent prostate cancer cell xenografts. Furthermore, elevation of FBXW7 protein levels and reduction of c-MYC protein levels were found in the xenografts of GUTK-treated compared with vehicle-treated mice. Hence, we have identified a compound that is capable of impeding cell cycle re-entry by quiescent PTEN(null)/p53(WT) and PTEN(null)/p53(mut) prostate cancer cells likely by promoting c-MYC protein degradation through stabilization of FBXW7. Its usage as a clinical modality to

  1. c-Myc activates BRCA1 gene expression through distal promoter elements in breast cancer cells

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    2011-01-01

    Background The BRCA1 gene plays an important role in the maintenance of genomic stability. BRCA1 inactivation contributes to breast cancer tumorigenesis. An increasing number of transcription factors have been shown to regulate BRCA1 expression. c-Myc can act as a transcriptional activator, regulating up to 15% of all genes in the human genome and results from a high throughput screen suggest that BRCA1 is one of its targets. In this report, we used cultured breast cancer cells to examine the mechanisms of transcriptional activation of BRCA1 by c-Myc. Methods c-Myc was depleted using c-Myc-specific siRNAs in cultured breast cancer cells. BRCA1 mRNA expression and BRCA1 protein expression were determined by quantitative RT-PCR and western blot, respectively and BRCA1 promoter activities were examined under these conditions. DNA sequence analysis was conducted to search for high similarity to E boxes in the BRCA1 promoter region. The association of c-Myc with the BRCA1 promoter in vivo was tested by a chromatin immunoprecipitation assay. We investigated the function of the c-Myc binding site in the BRCA1 promoter region by a promoter assay with nucleotide substitutions in the putative E boxes. BRCA1-dependent DNA repair activities were measured by a GFP-reporter assay. Results Depletion of c-Myc was found to be correlated with reduced expression levels of BRCA1 mRNA and BRCA1 protein. Depletion of c-Myc decreased BRCA1 promoter activity, while ectopically expressed c-Myc increased BRCA1 promoter activity. In the distal BRCA1 promoter, DNA sequence analysis revealed two tandem clusters with high similarity, and each cluster contained a possible c-Myc binding site. c-Myc bound to these regions in vivo. Nucleotide substitutions in the c-Myc binding sites in these regions abrogated c-Myc-dependent promoter activation. Furthermore, breast cancer cells with reduced BRCA1 expression due to depletion of c-Myc exhibited impaired DNA repair activity. Conclusions The distal

  2. The c-myc mRNA and helicobacter pylori infection and the relationship between the programmed cell death in the with Gastric cancer in the patients with gastric cancer%胃癌变患者c-myc mRNA与幽门螺杆菌感染及细胞程序性死亡的关系

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    潘晟; 罗浩; 李力

    2013-01-01

    Objective To discuss different stomach trouble change occurred in the process of development until the progression in patients with c-myc mRNA expression in correlation with helicobacter pylori (Hp) infection and its relationship with gastric tissue programmed cell death.Methods By real-time fluorescent quantitative reverse transcription-olymerase chain reaction (FQ-PCR) to detect 72 cases of chronic superficial gastritis (CSG),55 cases of chronic atrophic gastritis (the CAG),52 cases of intestinal metaplasia (IM),46 cases of atypical hyperplasia (AH),65 cases of gastric cancer (GC) group (CSG group,respectively,the CAG group,IM,AM group,AH,the GC group) in the c-myc mRNA expression;Rapid enzymatic urea,Warthin Starry silver staining and toluidine blue staining assay for gastric mucosa Hp infection;In situ end labeling (TUNEL) method to detect gastric mucosal cell apoptosis index (AI).Results CSG group,the CAG group,IM,AM group,AH,the GC group c-myc in gastric mucosa tissue mRNA positive example were 21.5% (7/31),31.0% (8/27),41.0% (10/26),59.1% (14/24) and 69.1 (23/33),c-myc relative mRNA expression levels were 0.089 ± 0.002,0.01 13 ± 0.014 mm,0.168 ±0.028,0.226,0.367 ±0.037 mm,0.040 mm IM,AH group,GC group c-myc amount of mRNA expression were higher than in CSG,the CAG group (P < 0.01),the AH group is higher than the IM group (P <0.01),the GC group higher than IM,AH group (P <0.01).C-myc mRNA expression quantity and negatively correlated with gastric mucosa cells AI (rs =-0.700,P <0.05) ;IM,AH group,GC group Hp positive patients with gastric mucosa cell c-myc mRNA expression were higher than Hp negative patients (P <0.05 or 0.01).Conclusion In the process of the gastric mucosal canceration,Hp infection can increase gastric mucosa cell c-myc mRNA expression,and inhibition of special-shaped programmed cell death (apoptosis) and play a role of cancer.%目的 探讨不同胃病变患者的发生发展直至恶变过程中c-myc mRNA的表达与

  3. Linc-RoR promotes c-Myc expression through hnRNP I and AUF1

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    Huang, Jianguo; Zhang, Ali; Ho, Tsui-Ting; Zhang, Ziqiang; Zhou, Nanjiang; Ding, Xianfeng; Zhang, Xu; Xu, Min; Mo, Yin-Yuan

    2016-01-01

    Linc-RoR was originally identified to be a regulator for induced pluripotent stem cells in humans and it has also been implicated in tumorigenesis. However, the underlying mechanism of Linc-RoR-mediated gene expression in cancer is poorly understood. The present study demonstrates that Linc-RoR plays an oncogenic role in part through regulation of c-Myc expression. Linc-RoR knockout (KO) suppresses cell proliferation and tumor growth. In particular, Linc-RoR KO causes a significant decrease in c-Myc whereas re-expression of Linc-RoR in the KO cells restores the level of c-Myc. Mechanistically, Linc-RoR interacts with heterogeneous nuclear ribonucleoprotein (hnRNP) I and AU-rich element RNA-binding protein 1 (AUF1), respectively, with an opposite consequence to their interaction with c-Myc mRNA. While Linc-RoR is required for hnRNP I to bind to c-Myc mRNA, interaction of Linc-RoR with AUF1 inhibits AUF1 to bind to c-Myc mRNA. As a result, Linc-RoR may contribute to the increased stability of c-Myc mRNA. Although hnRNP I and AUF1 can interact with many RNA species and regulate their functions, with involvement of Linc-RoR they would be able to selectively regulate mRNA stability of specific genes such as c-Myc. Together, these results support a role for Linc-RoR in c-Myc expression in part by specifically enhancing its mRNA stability, leading to cell proliferation and tumorigenesis. PMID:26656491

  4. Dose-dependent regulation of target gene expression and cell proliferation by c-Myc levels.

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    Schuhmacher, Marino; Eick, Dirk

    2013-01-01

    The proto-oncogene c-myc encodes a basic helix-loop-helix leucine zipper transcription factor (c-Myc). c-Myc plays a crucial role in cell growth and proliferation. Here, we examined how expression of c-Myc target genes and cell proliferation depend on variation of c-Myc protein levels. We show that proliferation rates, the number of cells in S-phase, and cell size increased in a dose-dependent manner in response to increasing c-Myc levels. Likewise, the mRNA levels of c-Myc responsive genes steadily increased with rising c-Myc levels. Strikingly, steady-state mRNA levels of c-Myc target genes did not saturate even at highest c-Myc concentrations. These characteristics predestine c-Myc levels as a cellular rheostat for the control and fine-tuning of cell proliferation and growth rates.

  5. ROCK has a crucial role in regulating prostate tumor growth through interaction with c-Myc.

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    Zhang, C; Zhang, S; Zhang, Z; He, J; Xu, Y; Liu, S

    2014-12-04

    Rho-associated kinase (ROCK) has an essential role in governing cell morphology and motility, and increased ROCK activity contributes to cancer cell invasion and metastasis. Burgeoning data suggest that ROCK is also involved in the growth regulation of tumor cells. However, thus far, the molecular mechanisms responsible for ROCK-governed tumor cell growth have not been clearly elucidated. Here we showed that inhibition of ROCK kinase activity, either by a selective ROCK inhibitor Y27632 or by specific ROCK small interfering RNA (siRNA) molecules, attenuated not only motility but also the proliferation of PC3 prostate cancer cells in vitro and in vivo. Importantly, mechanistic investigation revealed that ROCK endowed cancer cells with tumorigenic capability, mainly by targeting c-Myc. ROCK could increase the transcriptional activity of c-Myc by promoting c-Myc protein stability, and ROCK inhibition reduced c-Myc-mediated expression of mRNA targets (such as HSPC111) and microRNA targets (such as miR-17-92 cluster). We provided evidence demonstrating that ROCK1 directly interacted with and phosphorylated c-Myc, resulting in stabilization of the protein and activation of its transcriptional activity. Suppression of ROCK-c-Myc downstream molecules, such as c-Myc-regulated miR-17, also impaired tumor cell growth in vitro and in vivo. In addition, c-Myc was shown to exert a positive feedback regulation on ROCK by increasing RhoA mRNA expression. Therefore, inhibition of ROCK and its stimulated signaling might prove to be a promising strategy for restraining tumor progression in prostate cancer.

  6. Regulation of c-Myc expression by the histone demethylase JMJD1A is essential for prostate cancer cell growth and survival

    Science.gov (United States)

    Fan, Lingling; Peng, Guihong; Sahgal, Natasha; Fazli, Ladan; Gleave, Martin; Zhang, Yuji; Hussain, Arif; Qi, Jianfei

    2015-01-01

    The histone demethylase JMJD1A, which controls gene expression by epigenetic regulation of H3K9 methylation marks, functions in diverse activities, including spermatogenesis, metabolism, and stem cell self-renewal and differentiation. Here, we found that JMJD1A knockdown in prostate cancer cells antagonizes their proliferation and survival. Profiling array analyses revealed that JMJD1A-dependent genes function in cellular growth, proliferation and survival, and implicated that the c-Myc transcriptional network is de-regulated following JMJD1A inhibition. Biochemical analyses confirmed that JMJD1A enhances c-Myc transcriptional activity by upregulating c-Myc expression levels. Mechanistically, JMJD1A activity promoted recruitment of androgen receptor (AR) to the c-Myc gene enhancer and induced H3K9 demethylation, increasing AR-dependent transcription of c-Myc mRNA. In parallel, we found that JMJD1A regulated c-Myc stability, likely by inhibiting HUWE1, an E3 ubiquitin ligase known to target degradation of several substrates including c-Myc. JMJD1A (wild-type or mutant lacking histone demethylase activity) bound to HUWE1, attenuated HUWE1-dependent ubiquitination and subsequent degradation of c-Myc, increasing c-Myc protein levels. Furthermore, c-Myc knockdown in prostate cancer cells phenocopied effects of JMJD1A knockdown, and c-Myc re-expression in JMJD1A-knockdown cells partially rescued prostate cancer cell growth in vitro and in vivo. c-Myc protein levels were positively correlated with those of JMJD1A in a subset of human prostate cancer specimens. Collectively, our findings identify a critical role for JMJD1A in regulating proliferation and survival of prostate cancer cells by controlling c-Myc expression at transcriptional and post-translational levels. PMID:26279298

  7. Acidosis decreases c-Myc oncogene expression in human lymphoma cells: a role for the proton-sensing G protein-coupled receptor TDAG8.

    Science.gov (United States)

    Li, Zhigang; Dong, Lixue; Dean, Eric; Yang, Li V

    2013-10-11

    Acidosis is a biochemical hallmark of the tumor microenvironment. Here, we report that acute acidosis decreases c-Myc oncogene expression in U937 human lymphoma cells. The level of c-Myc transcripts, but not mRNA or protein stability, contributes to c-Myc protein reduction under acidosis. The pH-sensing receptor TDAG8 (GPR65) is involved in acidosis-induced c-Myc downregulation. TDAG8 is expressed in U937 lymphoma cells, and the overexpression or knockdown of TDAG8 further decreases or partially rescues c-Myc expression, respectively. Acidic pH alone is insufficient to reduce c-Myc expression, as it does not decrease c-Myc in H1299 lung cancer cells expressing very low levels of pH-sensing G protein-coupled receptors (GPCRs). Instead, c-Myc is slightly increased by acidosis in H1299 cells, but this increase is completely inhibited by ectopic overexpression of TDAG8. Interestingly, TDAG8 expression is decreased by more than 50% in human lymphoma samples in comparison to non-tumorous lymph nodes and spleens, suggesting a potential tumor suppressor function of TDAG8 in lymphoma. Collectively, our results identify a novel mechanism of c-Myc regulation by acidosis in the tumor microenvironment and indicate that modulation of TDAG8 and related pH-sensing receptor pathways may be exploited as a new approach to inhibit Myc expression.

  8. Acidosis Decreases c-Myc Oncogene Expression in Human Lymphoma Cells: A Role for the Proton-Sensing G Protein-Coupled Receptor TDAG8

    Directory of Open Access Journals (Sweden)

    Zhigang Li

    2013-10-01

    Full Text Available Acidosis is a biochemical hallmark of the tumor microenvironment. Here, we report that acute acidosis decreases c-Myc oncogene expression in U937 human lymphoma cells. The level of c-Myc transcripts, but not mRNA or protein stability, contributes to c-Myc protein reduction under acidosis. The pH-sensing receptor TDAG8 (GPR65 is involved in acidosis-induced c-Myc downregulation. TDAG8 is expressed in U937 lymphoma cells, and the overexpression or knockdown of TDAG8 further decreases or partially rescues c-Myc expression, respectively. Acidic pH alone is insufficient to reduce c-Myc expression, as it does not decrease c-Myc in H1299 lung cancer cells expressing very low levels of pH-sensing G protein-coupled receptors (GPCRs. Instead, c-Myc is slightly increased by acidosis in H1299 cells, but this increase is completely inhibited by ectopic overexpression of TDAG8. Interestingly, TDAG8 expression is decreased by more than 50% in human lymphoma samples in comparison to non-tumorous lymph nodes and spleens, suggesting a potential tumor suppressor function of TDAG8 in lymphoma. Collectively, our results identify a novel mechanism of c-Myc regulation by acidosis in the tumor microenvironment and indicate that modulation of TDAG8 and related pH-sensing receptor pathways may be exploited as a new approach to inhibit Myc expression.

  9. Pokemon mRNA在乳腺癌中的表达及与c- myc相关性分析%Expression of Pokemon mRNA in breast carcinoma and its relationship to c-myc

    Institute of Scientific and Technical Information of China (English)

    付朝江; 崔明; 徐衍; 王应霞

    2011-01-01

    目的:探讨人乳腺癌中原癌基因c-myc和Pokemon mRNA在乳腺癌组织中的表达及其与乳腺癌发生、转移的相关性.方法:收集浸润性导管癌组织、癌旁乳腺组织、正常乳腺组织各45、20和20例,用原位杂交法检测Pokemon mRNA表达,并用免疫组织化学法检测浸润性导管癌c-myc表达,并进行统计分析.结果:乳腺癌细胞质Pokemon mRNA的表达率为71.2%(37/45),显著高于癌旁正常乳腺组织40%(8/20)、乳腺增生组织25%(5/20), 三者有显著性差异 (P<0.05),细胞质c-myc阳性率分别为86.67%、60.0%、50.0%,三者有显著性差异(P<0.05).细胞质Pokemon mRNA表达与乳腺癌淋巴结转移、组织学分级相关(P<0.05).细胞质c-myc表达与乳腺癌腋窝淋巴结转移相关(P<0.05).45例乳腺癌细胞质Pokemon mRNA与c-myc表达呈正相关(γ=0.585 ,P<0.05).结论:Pokemon mRNA的表达可能在乳腺导管癌的组织发生中起关键作用,c-myc的过度表达可能与乳腺癌Pokemon基因转录激活有关.%Objective: To explore the expression and interaction of Pokemon mRNA and proto - oncogene c - myc in the course of carcinogenesis and metastasis of breast cancer.Methods : The expression of Pokemon mRNA was examined by in situhybridization in 45 cases of breast cancer,20 cases of adjacent noncancerous breast tissue and 20 cases of mammary gland hyperplasia,The expression of c - myc was examined by immunohistochemistry in 45 cases of carcinoma.Results:The rate of strong positive plasma Pokemon mRNA and c - myc expression was significandy higher in breast cancer than in adjacent noncancerous breast tissue and mammary gland hyperplasia ( P < 0.05 ) , the rates of strong positive plasma Pokemon expression were 71.2% ( 37/45 ) ,40% ( 8/20) , 25 % ( 5/20) ;86.67% 、60.0% 、50.0% , respectively.The positive expreasion of Pokemon mRNA and c - myc in breast cancer was strongly related to lympb nodemetastasis(P <0.05) .The expre8aion of Pokemon mRNA

  10. Ribosomal Protein S14 Negatively Regulates c-Myc Activity*

    Science.gov (United States)

    Zhou, Xiang; Hao, Qian; Liao, Jun-ming; Liao, Peng; Lu, Hua

    2013-01-01

    The ribosomal gene RPS14 is associated with the cancer-prone 5q-syndrome, which is caused by an interstitial deletion of the long arm of human chromosome 5. Previously, we found that ribosomal protein S14 (RPS14) binds to and inactivates MDM2, consequently leading to p53-dependent cell-cycle arrest and growth inhibition. However, it remains elusive whether RPS14 regulates cell proliferation in a p53-independent manner. Here, we show that RPS14 interacts with the Myc homology box II (MBII) and the C-terminal basic helix-loop-helix leucine zipper (bHLH-LZ) domains of the oncoprotein c-Myc. Further, RPS14 inhibited c-Myc transcriptional activity by preventing the recruitment of c-Myc and its cofactor, TRRAP, to the target gene promoters, as thus suppressing c-Myc-induced cell proliferation. Also, siRNA-mediated RPS14 depletion elevated c-Myc transcriptional activity determined by its target gene, Nucleolin, expression. Interestingly, RPS14 depletion also resulted in the induction of c-Myc mRNA and subsequent protein levels. Consistent with this, RPS14 promoted c-Myc mRNA turnover through an Argonaute 2 (Ago2)- and microRNA-mediated pathway. Taken together, our study demonstrates that RPS14 negates c-Myc functions by directly inhibiting its transcriptional activity and mediating its mRNA degradation via miRNA. PMID:23775087

  11. The long non-coding RNA GAS5 cooperates with the eukaryotic translation initiation factor 4E to regulate c-Myc translation.

    Directory of Open Access Journals (Sweden)

    Guangzhen Hu

    Full Text Available Long noncoding RNAs (lncRNAs are important regulators of transcription; however, their involvement in protein translation is not well known. Here we explored whether the lncRNA GAS5 is associated with translation initiation machinery and regulates translation. GAS5 was enriched with eukaryotic translation initiation factor-4E (eIF4E in an RNA-immunoprecipitation assay using lymphoma cell lines. We identified two RNA binding motifs within eIF4E protein and the deletion of each motif inhibited the binding of GAS5 with eIF4E. To confirm the role of GAS5 in translation regulation, GAS5 siRNA and in vitro transcribed GAS5 RNA were used to knock down or overexpress GAS5, respectively. GAS5 siRNA had no effect on global protein translation but did specifically increase c-Myc protein level without an effect on c-Myc mRNA. The mechanism of this increase in c-Myc protein was enhanced association of c-Myc mRNA with the polysome without any effect on protein stability. In contrast, overexpression of in vitro transcribed GAS5 RNA suppressed c-Myc protein without affecting c-Myc mRNA. Interestingly, GAS5 was found to be bound with c-Myc mRNA, suggesting that GAS5 regulates c-Myc translation through lncRNA-mRNA interaction. Our findings have uncovered a role of GAS5 lncRNA in translation regulation through its interactions with eIF4E and c-Myc mRNA.

  12. hTERT protein expression is independent of clinicopathological parameters and c-Myc protein expression in human breast cancer

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    Meligonis G

    2005-01-01

    Full Text Available Abstract Background Telomerase is a ribonucleoprotein enzyme that synthesises telomeres after cell division and maintains chromosomal length and stability thus leading to cellular immortalisation. The hTERT (human telomerase reverse transcriptase subunit seems to be the rate-limiting determinant of telomerase and knowledge of factors controlling hTERT transcription may be useful in therapeutic strategies. The hTERT promoter contains binding sites for c-Myc and there is some experimental and in vitro evidence that c-Myc may increase hTERT expression. We previously reported no correlation between c-Myc mRNA expression and hTERT mRNA or telomerase activity in human breast cancer. This study aims to examine the correlation between hTERT expression as determined by immunohistochemistry and c-Myc expression, lymph node status, and tumour size and grade in human breast cancer. Materials and methods The immunohistochemical expression of hTERT and c-Myc was investigated in 38 malignant breast tumours. The expression of hTERT was then correlated with the lymph node status, c-Myc expression and other clinicopathological parameters of the tumours. Results hTERT expression was positive in 27 (71% of the 38 tumours. 15 (79% of 19 node positive tumours were hTERT positive compared with 11 (63% of 19 node negative tumours. The expression was higher in node positive tumours but this failed to reach statistical significance (p = 0.388. There was no significant association with tumour size, tumour grade or c-Myc expression. However, hTERT expression correlated positively with patients' age (correlation coefficient = 0.415, p = 0.0097. Conclusion hTERT protein expression is independent of lymph node status, tumour size and grade and c-Myc protein expression in human breast cancer

  13. Deubiquitinating c-Myc: USP36 steps up in the nucleolus.

    Science.gov (United States)

    Sun, Xiao-Xin; Sears, Rosalie C; Dai, Mu-Shui

    2015-01-01

    Ubiquitination plays a key and complex role in the regulation of c-Myc stability, transactivation, and oncogenic activity. c-Myc is ubiquitinated by a number of ubiquitin ligases (E3s), such as SCF(Fbw7) and SCF(Skp2). Depending on the E3s, ubiquitination can either positively or negatively regulate c-Myc levels and activity. Meanwhile, c-Myc ubiquitination can be reversed by deubiquitination. An early study showed that USP28 deubiquitinates c-Myc via interacting with Fbw7α whereas a recent study reveals that USP37 deubiquitinates c-Myc independently of Fbw7 and c-Myc phosphorylation. Consequently, both USP28 and USP37 stabilize c-Myc and enhance its activity. We recently found the nucleolar USP36 as a novel c-Myc deubiquitinase that controls the end-point of c-Myc degradation pathway in the nucleolus. Here we briefly review the current understanding of ubiquitination and deubiquitination regulation of c-Myc and further discuss the USP36-c-Myc regulatory pathway.

  14. Rabring7 Degrades c-Myc through Complex Formation with MM-1

    Science.gov (United States)

    Torii, Ayako; Tashiro, Erika; Miyazawa, Makoto; Ariga, Hiroyoshi; Iguchi-Ariga, Sanae M. M.

    2012-01-01

    We have reported that a novel c-Myc-binding protein, MM-1, repressed E-box-dependent transcription and transforming activities of c-Myc and that a mutation of A157R in MM-1, which is often observed in patients with leukemia or lymphoma, abrogated all of the repressive activities of MM-1 toward c-Myc, indicating that MM-1 is a novel tumor suppressor. MM-1 also binds to the ubiquitin-proteasome system, leading to degradation of c-Myc. In this study, we identified Rabring7, a Rab7-binding and RING finger-containing protein, as an MM-1-binding protein, and we found that Rabring7 mono-ubiquitinated MM-1 in the cytoplasm without degradation of MM-1. Rabring7 was also found to bind to c-Myc and to ubiquitinate c-Myc in a threonine 58-dependent manner. When c-Myc was co-transfected with MM-1 and Rabring7, c-Myc was degraded. Furthermore, it was found that c-Myc was stabilized in MM-1-knockdown cells even when Rabring7 was transfected and that Rabring7 was bound to and co-localized with MM-1 and c-Myc after MM-1 and Rabring7 had been translocated from the cytoplasm to the nucleus. These results suggest that Rabring7 stimulates c-Myc degradation via mono-ubiquitination of MM-1. PMID:22844532

  15. Rabring7 degrades c-Myc through complex formation with MM-1.

    Directory of Open Access Journals (Sweden)

    Rina Narita

    Full Text Available We have reported that a novel c-Myc-binding protein, MM-1, repressed E-box-dependent transcription and transforming activities of c-Myc and that a mutation of A157R in MM-1, which is often observed in patients with leukemia or lymphoma, abrogated all of the repressive activities of MM-1 toward c-Myc, indicating that MM-1 is a novel tumor suppressor. MM-1 also binds to the ubiquitin-proteasome system, leading to degradation of c-Myc. In this study, we identified Rabring7, a Rab7-binding and RING finger-containing protein, as an MM-1-binding protein, and we found that Rabring7 mono-ubiquitinated MM-1 in the cytoplasm without degradation of MM-1. Rabring7 was also found to bind to c-Myc and to ubiquitinate c-Myc in a threonine 58-dependent manner. When c-Myc was co-transfected with MM-1 and Rabring7, c-Myc was degraded. Furthermore, it was found that c-Myc was stabilized in MM-1-knockdown cells even when Rabring7 was transfected and that Rabring7 was bound to and co-localized with MM-1 and c-Myc after MM-1 and Rabring7 had been translocated from the cytoplasm to the nucleus. These results suggest that Rabring7 stimulates c-Myc degradation via mono-ubiquitination of MM-1.

  16. c-myc in whitefish (Coregonus lavaretus): structure, expression, and insights into possible posttranscriptional regulatory mechanism.

    Science.gov (United States)

    Brzuzan, P; Kramer, C; Łakomiak, A; Jakimiuk, E; Florczyk, M; Woźny, M

    2015-10-01

    c-myc has a crucial function in growth control, differentiation, and apoptosis of vertebrate cells. Despite the important role of c-myc in mediating the biological effects, studies of c-myc gene expression and factors that control it in organisms other than mammals, such as fish, have been rare. In the current study, we asked whether c-myc mRNA of whitefish, a feasible organism for pollution monitoring in aquatic systems and a model in toxicological research, contains activity sites for regulatory motifs in its 5'- and 3'-UTRs, similar to those found in mammals. We were particularly interested in whether miRNA-34, a known negative regulator of c-myc's in mammals, is able to regulate c-myc in fish. To answer these questions, we determined the mRNA sequence of whitefish c-myc and inferred the structure of the protein that it codes for. We found that the active sites of mRNA and structures of the inferred c-myc protein are similar to those found in mammals and other fish. Remarkably, levels of c-myc mRNA expression were very high in ovaries compared to other tissues of whitefish, thus corroborating previous data in fish. Using bioinformatic searches on c-myc 3'-UTR, we confirmed the presence of two miRNA-34a (miR-34a) response elements. Luciferase reporter assay showed that activity of reporters containing either the miR response elements or entire c-myc 3'-UTR was significantly reduced (p c-myc gene silencing by profiling the expression of both genes in livers of whitefish treated for 8, 24, 48 h with MC-LR, a potent c-myc inducer in mammals. Although the difference was only significant at p = 0.08, the expression of c-myc mRNA in challenged whitefish after 24 h of the treatment was notably higher than that in livers of control fish. Concurrently, we noticed slight but significant up-regulation of miR-34a after 24 and 48 h of the challenge (p c-myc mRNA levels and miR-34a expression. Together, these results suggest that miR-34a might regulate c-myc gene

  17. [The expression of c-myc in the tissues of human laryngeal squamous cell carcinoma and the effect of siRNA-mediated inhibition of c-myc on proliferation in laryngeal carcinoma Hep-2 cells].

    Science.gov (United States)

    Sang, Jianzhong; Liu, Li; Tian, Fang; Jin, Hongjun; Yuan, Linlin; Lou, Weihua

    2011-08-01

    To detect the expression of c-myc in the tissue of laryngeal squamous cell carcinoma. RNA interference(RNAi) was employed to inhibit the expression of c-myc in Hep-2 cells and to evaluate the effects of c-myc as a target for gene therapy in laryngeal carcinoma. Immunohistochemistry was used to determine the protein levels of c-myc and Rb in 80 cases of laryngeal squamous cell carcinoma and 30 cases of polyp of vocal cord. Hep-2 cells were transfected with c-myc siRNA, c-myc protein and mRNA levels were detected using Western Blotting and RT-PCR. Cell viability was detected by MTT after the Hep-2 cells were transfected with c-myc siRNA for different times or transfected with different concentrations c-myc siRNA. The sensitivity of Hep-2 cells to 5-Fu transfected with or without c-myc siRNA was evaluated also by MTT. Hep-2 cells were transfected with c-myc siRNA in combination with 5-Fu for 48 h and then analyzed cell apoptosis by flow cytometry. Immunohistochemical analysis showed that c-myc was highly expressed in the tissues of laryngeal squamous cell carcinoma while the expression of Rb was lower. The protein and mRNA levels of c-myc decreased after transfected with c-myc siRNA. The results of MTT showed that the c-myc siRNA inhibited Hep-2 cells growth in a concentration-dependent manner. When transfected with c-myc siRNA(50 nmol/L), the cells were inhibited in a time-dependent manner. Compared with the untransfected cells, the viability of transfected Hep-2 cells was significantly suppressed at the same concentration of 5-Fu (P Hep-2 cells to 5-Fu. Therefore,c-myc might be a good target for cancer treatment.

  18. 艾灸对实验性类风湿关节炎滑膜细胞原癌基因 c-fos和c-myc mRNA表达的影响%Effects of moxibustion on the expression of protooncogene c-fos and c-myc mRNA in experimental arthritis

    Institute of Scientific and Technical Information of China (English)

    余俊辉; 刘旭光; 余曙光; 蔡美英; 周昌华; 赵宗蓉; 张平

    2005-01-01

    目的观察艾灸对实验性类风湿关节炎滑膜细胞原癌基因c-fos、c-myc mRNA表达的影响,初步探讨艾灸对RA滑膜细胞内分子信号传导的调控.方法在日本大耳白兔右后足踝关节部皮内注射福氏完全佐剂造模,经过艾灸治疗,通过半定量RT-PCR测定c-fos和c-myc mRNA的表达量.结果治疗组c-fos和c-myc mRNA表达量显著低于造模组(P<0.01).结论艾灸治疗能够降低c-fos和c-myc mRNA的表达,影响生长因子信号传导系统.

  19. Inauhzin(c) Inactivates c-Myc Independently of p53

    Science.gov (United States)

    Jung, Ji Hoon; Liao, Jun-Ming; Zhang, Qi; Zeng, Shelya; Nguyen, Daniel; Hao, Qian; Zhou, Xiang; Cao, Bo; Kim, Sung-Hoon; Lu, Hua

    2015-01-01

    Oncogene MYC is deregulated in many human cancers, especially in lymphoma. Previously, we showed that inauhzin (INZ) activates p53 and inhibits tumor growth. However, whether INZ could suppress cancer cell growth independently of p53 activity is still elusive. Here, we report that INZ(c), a second generation of INZ, suppresses c-Myc activity and thus inhibits growth of human lymphoma cells in a p53-independent manner. INZ(c) treatment decreased c-Myc expression at both mRNA and protein level, and suppressed c-Myc transcriptional activity in human Burkitt's lymphoma Raji cells with mutant p53. Also, we showed that overexpressing ectopic c-Myc rescues the inhibition of cell proliferation by INZ(c) in Raji cells, implicating c-Myc activity is targeted by INZ(c). Interestingly, the effect of INZ(c) on c-Myc expression was impaired by disrupting the targeting of c-Myc mRNA by miRNAs via knockdown of ribosomal protein (RP) L5, RPL11, or Ago2, a subunit of RISC complex, indicating that INZ(c) targets c-Myc via miRNA pathways. These results reveal a new mechanism that INZ(c) targets c-Myc activity in human lymphoma cells. PMID:25692307

  20. 氧化苦参碱对结肠癌LoVo细胞c-myc,PSMD9,CDK4mRNA表达的影响%Effect of Oxymatrine on Expression of c-myc, PSMD9 and CDK4 mRNA in Human Colon Carcinoma LoVo Cells

    Institute of Scientific and Technical Information of China (English)

    彭燕; 韩凌; 孙静; 危建安

    2012-01-01

    目的:探讨氧化苦参碱( oxymatrine,OM)抑制人结肠癌LoVo细胞增殖和诱导凋亡的分子作用机制.方法:采用流式细胞仪检测LoVo细胞凋亡率以及细胞周期分布;采用荧光定量PCR法检测0.25,0.5 g·L-1 OM对LoVo细胞增殖相关基因c -myc,蛋白酶调解因子9(PSMD9),CDK4的基因表达的影响.结果:0.5 g·L-1以下浓度的OM作用结肠癌LoVo细胞48 h,对细胞凋亡无明显影响.0.25 g·L-1 OM作用48 h时可明显抑制人结肠癌LoVo细胞c-myc基因表达(P<0.05).0.5g·L-1 OM作用48 h时可明显抑制LoVo细胞c-myc,CDK4的基因表达(P <0.01,P<0.01,).药物作用时间为96 h时,0.5g·L-1 OM可明显抑制c-myc,PSM D9,CDK4基因表达(P<0.05,或P<0.01).结论:较低剂量OM显著抑制人结肠癌LoVo细胞增殖的作用机制,可能与下调LoVo细胞c-myc,PSM D9,CDK4表达有关.%Objective: To explore the molecular mechanism of inhibiting colon cancer cell strein LoVo proliferation and inducing apoptosis by oxymatrine ( OM ) Method: Flow cytometry was used to detect the LoVo cells apoptosis and cell cycle distribution. Fluorescence quantitative PCR was used to detect cell proliferation-related genes like the c-myc, proteasome modulator 9 (PSMD9) , CDK4 gene expression when LoVo was treated with 0. 25, 0. 5 g · L-1OM. Result: OM had no significant effect on apoptosis in colon cancer LoVo cells when the treatment of OM lasted 48 h and the concentration was lower than 0.5, 0.25 g · L-1 OM can inhibit c-myc gene expression in LoVo when duration of action last 24 h ( P < 0. 05 ). When the dose increated to 0. 5 g · L-1 and duration of action was 48 h, OM could inhibit c-myc, CDK4 gene expression in LoVo cells (P <0. 01 , P < 0. 01). When duration of action was extended to 96 h, 0. 5 g · L-1 OM could inhibit the c-myc, PSMD9, CDK4 gene expression in LoVo cells ( P < 0. 05, P < 0. 01, P < 0. 01 ). Conclusion; OM at Lower dose could significantly inhibit the proliferation of human colon cancer Lo

  1. The role of c-Myc-RBM38 loop in the growth suppression in breast cancer.

    Science.gov (United States)

    Li, Xiao-Xia; Shi, Liang; Zhou, Xu-Jie; Wu, Jing; Xia, Tian-Song; Zhou, Wen-Bin; Sun, Xi; Zhu, Lei; Wei, Ji-Fu; Ding, Qiang

    2017-04-11

    RNA-binding protein 38 (RBM38) is a member of the RNA recognition motif (RRM) family of RNA-binding proteins (RBPs). RBM38 often exerts its function by forming regulatory loops with relevant genes. c-Myc is an oncogenic transcription factor that is upregulated in one-third of breast cancers and involved in many cellular processes in this malignancy. In our previous study, RBM38 was identified as a tumor suppressor in breast cancer. In the present study, we investigated the mechanisms underlying the regulation of this tumor suppressor. Lentivirus transfections, Western blotting analysis, qRT-PCR and immunohistochemistry were employed to study the expression of c-Myc and RBM38. Chromatin immunoprecipitation and dual-luciferase reporter assays were performed to investigate the direct relationship between c-Myc protein and the RBM38 gene. RNA immunoprecipitation combined with dual-luciferase reporter assays was conducted to confirm the direct relationship between the RBM38 protein and the c-Myc transcript. Knockdown of c-Myc increased RBM38 expression by binding directly to specific DNA sequences (5'-CACGTG-3'), known as the E-box motif, in the promoter region of RBM38 gene. Additionally, RBM38 destabilized the c-Myc transcript by directly targeting AU-rich elements (AREs) in the 3'-untranslated region (3'-UTR) of c-Myc mRNA to suppress c-Myc expression. Moreover, specific inhibitors of c-Myc transcriptional activity inhibited RBM38-induced suppression of growth, implying that RBM38 acts as a tumor suppressor via a mechanism that depends, at least partially, on the reduction of c-Myc expression in breast cancer. RBM38 and c-Myc form a unique mutually antagonistic RBM38-c-Myc loop in breast cancer.

  2. p53 inhibits the upregulation of sirtuin 1 expression induced by c-Myc.

    Science.gov (United States)

    Yuan, Fang; Liu, Lu; Lei, Yonghong; Tang, Peifu

    2017-10-01

    Sirtuin 1 (Sirt1), a conserved NAD(+) dependent deacetylase, is a mediator of life span by calorie restriction. However, Sirt1 may paradoxically increase the risk of cancer. Accordingly, the expression level of Sirt1 is selectively elevated in numerous types of cancer cell; however, the mechanisms underlying the differential regulation remain largely unknown. The present study demonstrated that oncoprotein c-Myc was a direct regulator of Sirt1, which accounts for the upregulation of Sirt1 expression only in the cells without functional p53. In p53 deficient cells, the overexpression of c-Myc increased Sirt1 mRNA and protein expression levels as well as its promoter activity, whereas the inhibitor of c-Myc, 10058-F4, induced decreased Sirt1 basal mRNA and protein expression levels. Deletion/mutation mapping analyses revealed that c-Myc bound to the conserved E-box[-189 to -183 base pair (bp)] of the Sirt1 promoter. In addition, p53 and c-Myc shared at least response element and the presence of p53 may block the binding of c-Myc to the Sirt1 promoter, thus inhibit the c-Myc mediated upregulation of Sirt1 promoter activity. The present study indicated that the expression level of Sirt1 was tightly regulated by oncoprotein c-Myc and tumor suppressor p53, which aids an improved understanding of its expression regulation and tumor promoter role in certain conditions.

  3. In silico identification of novel ligands for G-quadruplex in the c-MYC promoter.

    Science.gov (United States)

    Kang, Hyun-Jin; Park, Hyun-Ju

    2015-04-01

    G-quadruplex DNA formed in NHEIII1 region of oncogene promoter inhibits transcription of the genes. In this study, virtual screening combining pharmacophore-based search and structure-based docking screening was conducted to discover ligands binding to G-quadruplex in promoter region of c-MYC. Several hit ligands showed the selective PCR-arresting effects for oligonucleotide containing c-MYC G-quadruplex forming sequence. Among them, three hits selectively inhibited cell proliferation and decreased c-MYC mRNA level in Ramos cells, where NHEIII1 is included in translocated c-MYC gene for overexpression. Promoter assay using two kinds of constructs with wild-type and mutant sequences showed that interaction of these ligands with the G-quadruplex resulted in turning-off of the reporter gene. In conclusion, combined virtual screening methods were successfully used for discovery of selective c-MYC promoter G-quadruplex binders with anticancer activity.

  4. MicroRNA-130a associates with ribosomal protein L11 to suppress c-Myc expression in response to UV irradiation

    Science.gov (United States)

    Li, Yuhuang; Challagundla, Kishore B.; Sun, Xiao-Xin; Zhang, Qinghong; Dai, Mu-Shui

    2015-01-01

    The oncoprotein c-Myc is essential for cell growth and proliferation while its deregulated overexpression is associated with most human cancers. Thus tightly regulated levels and activity of c-Myc are critical for maintaining normal cell homeostasis. c-Myc is down-regulated in response to several types of stress, including UV-induced DNA damage. Yet, mechanism underlying UV-induced c-Myc reduction is not completely understood. Here we report that L11 promotes miR-130a targeting of c-myc mRNA to repress c-Myc expression in response to UV irradiation. miR-130a targets the 3′-untranslated region (UTR) of c-myc mRNA. Overexpression of miR-130a promotes the Ago2 binding to c-myc mRNA, significantly reduces the levels of both c-Myc protein and mRNA and inhibits cell proliferation. UV treatment markedly promotes the binding of L11 to miR-130a, c-myc mRNA as well as Ago2 in cells. Inhibiting miR-130a significantly suppresses UV-mediated c-Myc reduction. We further show that L11 is relocalized from the nucleolus to the cytoplasm where it associates with c-myc mRNA upon UV treatment. Together, these results reveal a novel mechanism underlying c-Myc down-regulation in response to UV-mediated DNA damage, wherein L11 promotes miR-130a-loaded miRISC to target c-myc mRNA. PMID:25544755

  5. FBXO32 Targets c-Myc for Proteasomal Degradation and Inhibits c-Myc Activity*

    Science.gov (United States)

    Mei, Zhichao; Zhang, Dawei; Hu, Bo; Wang, Jing; Shen, Xian; Xiao, Wuhan

    2015-01-01

    FBXO32 (MAFbx/Atrogin-1) is an E3 ubiquitin ligase that is markedly up-regulated in muscle atrophy. Although some data indicate that FBXO32 may play an important role in tumorigenesis, the molecular mechanism of FBXO32 in tumorigenesis has been poorly understood. Here, we present evidence that FBXO32 targets the oncogenic protein c-Myc for ubiquitination and degradation through the proteasome pathway. Phosphorylation of c-Myc at Thr-58 and Ser-62 is dispensable for FBXO32 to induce c-Myc degradation. Mutation of the lysine 326 in c-Myc reduces c-Myc ubiquitination and prevents the c-Myc degradation induced by FBXO32. Furthermore, overexpression of FBXO32 suppresses c-Myc activity and inhibits cell growth, but knockdown of FBXO32 enhances c-Myc activity and promotes cell growth. Finally, we show that FBXO32 is a direct downstream target of c-Myc, highlighting a negative feedback regulation loop between c-Myc and FBXO32. Thus, FBXO32 may function by targeting c-Myc. This work explains the function of FBXO32 and highlights its mechanisms in tumorigenesis. PMID:25944903

  6. Targeting c-Myc on cell growth and vascular endothelial growth factor expression in IN500 glioblastoma cells

    Institute of Scientific and Technical Information of China (English)

    HU Yu-hua; KONG Shi-qi; KONG Hai-bo; WU Jian-liang; CHEN Ze

    2012-01-01

    Background The level of c-Myc is closely associated with high pathological grade and the poor prognosis of gliomas.Vascular endothelial growth factor (VEGF) is the most important angiogenic factor that potently stimulates the proliferation and migration of vascular endothelial cells.This study aimed to address the biological importance of c-Myc in the development of gliomas,we downregulated the expression of c-Myc in the human glioblastoma cell line IN500 and studied the in vitro effect on cellular growth,proliferation,and apoptosis and the expression of VEGF and the in vivo effect on tumor formation in a xenograft mouse model.Methods IN500△ cells were stably transfected with shRNA-expressing plasmids for either c-Myc (pCMYC-shRNA) or as a control (pCtrl-shRNA).Following establishment of stable cells,the mRNA expressions of c-Myc and VEGF were examined by reverse transcription (RT)-PCR,and c-Myc and VEGF proteins by Western blotting and immunohistochemistry.Cell-cycle progression and apoptosis were determined by flow cytometry.The in vivo effect of targeting c-Myc was determined by subcutaneous injection of stable cells into immunodeficient nude mice.Results The stable transfection of pCMYC-shRNA successfully knocked down the steady-state mRNA and protein levels of c-Myc in IN500,which positively correlated with the downregulation of VEGF.Downregulating c-Myc in vitro also led to G1-S arrest and enhanced apoptosis.In vivo,targeting c-Myc reduced xenograft tumor formation and resulted in significantly smaller tumors.Conclusions c-Myc has multiple functions in glioblastoma development that include regulating cell-cycle,apoptosis,and VEGF expression.Targeting c-Myc expression may be a promising therapy for malignant glioma.

  7. c-MYC-induced genomic instability

    National Research Council Canada - National Science Library

    Kuzyk, Alexandra; Mai, Sabine

    2014-01-01

    ...% of all tumors have some form of c-MYC gene dysregulation, which affects gene regulation, microRNA expression profiles, large genomic amplifications, and the overall organization of the nucleus...

  8. Increased transcription of the c-myc oncogene in two methylcholanthrene-induced quail fibroblastic cell lines

    Energy Technology Data Exchange (ETDEWEB)

    Saule, S.; Martin, P.; Gegonne, A.; Begue, A.; Lagrou, C.; Stehelin, D.

    1984-12-01

    The expression of three c-onc genes (c-erb, c-myc, c-myb) was investigated in five cell lines established from fibrosarcomas induced with 20-methylcholanthrene (MCA) of Japanese quails. These cell lines showed low levels of the three c-onc genes, with the exception of two cell lines that accumulated moderate (MCAQ 1-4) and large amounts (MCAQ 3-5) of c-myc RNA. Molecular cloning and restriction endonuclease analyses indicated that expression of c-myc in these two cell lines were not associated with detectable rearrangements in the c-myc locus, that the size of the c-myc transcript (2.7 kb) in MCAQ 3-5 was similar to that of the normal c-myc messenger RNAs (mRNA) and that the transcriptional activatin observed in MCAQ 3-5 was not mediated by the LTR (long terminal repeat) of a proximate ALV (avian leukosis virus) provirus. Finally, when analyzed with the restriction enzymes Msp I and Hpa II, the c-myc locus of MCAQ 3-5 and MCAQ 1-4 was found hypomethylated as compared with that of the other cell lines tested that show low levels of c-myc transcripts. Results suggest that one of the ways methylcholanthrene could mediate transformation is by inducing an abnormal regulation of the c-myc gene.

  9. β-catenin regulates c-Myc and CDKN1A expression in breast cancer cells

    Science.gov (United States)

    Xu, Jinhua; Chen, Yinghua; Huo, Dezheng; Khramtsov, Andrey; Khramtsova, Galina; Zhang, Chunling; Goss, Kathleen H.; Olopade, Olufunmilayo I.

    2015-01-01

    We previously reported that the Wnt pathway is preferentially activated in basal-like breast cancer. However, the mechanisms by which the Wnt pathway regulates down-stream targets in basal-like breast cancer, and the biological significance of this regulation, are poorly understood. In this study, we found that c-Myc is highly expressed in the basal-like subtype by microarray analyses and immunohistochemical staining. After silencing β-catenin using siRNA, c-Myc expression was decreased in non-basal-like breast cancer cells. In contrast, c-Myc mRNA and protein expression was up-regulated in the basal-like breast cancer cell lines. Decreased c-Myc promoter activity was observed after inhibiting β-catenin by siRNA in non-basal-like breast cancer cells; however, inhibition of β-catenin or over-expression of dominant-negative LEF1 had no effect on c-Myc promoter activity in basal-like breast cancer cell lines. In addition, CDKN1A mRNA and p21 protein expression were significantly increased in all breast cancer cell lines upon β-catenin silencing. Interestingly, inhibiting β-catenin expression alone did not induce apoptosis in breast cancer cell lines despite c-Myc regulation, but we observed a modest increase of cells in the G1 phase of the cell cycle and decrease of cells in S phase upon β-catenin silencing. Our findings suggest that the regulation of c-Myc in breast cancer cells is dependent on the molecular subtype, and that β-catenin-mediated regulation of c-Myc and p21 may control the balance of cell death and proliferation in breast cancer. PMID:25663530

  10. Domain-specific c-Myc ubiquitylation controls c-Myc transcriptional and apoptotic activity

    Science.gov (United States)

    Zhang, Qin; Spears, Erick; Boone, David N.; Li, Zhaoliang; Gregory, Mark A.; Hann, Stephen R.

    2013-01-01

    The oncogenic transcription factor c-Myc causes transformation and tumorigenesis, but it can also induce apoptotic cell death. Although tumor suppressors are necessary for c-Myc to induce apoptosis, the pathways and mechanisms are unclear. To further understand how c-Myc switches from an oncogenic protein to an apoptotic protein, we examined the mechanism of p53-independent c-Myc–induced apoptosis. We show that the tumor suppressor protein ARF mediates this switch by inhibiting ubiquitylation of the c-Myc transcriptional domain (TD). Whereas TD ubiquitylation is critical for c-Myc canonical transcriptional activity and transformation, inhibition of ubiquitylation leads to the induction of the noncanonical c-Myc target gene, Egr1, which is essential for efficient c-Myc–induced p53-independent apoptosis. ARF inhibits the interaction of c-Myc with the E3 ubiquitin ligase Skp2. Overexpression of Skp2, which occurs in many human tumors, inhibits the recruitment of ARF to the Egr1 promoter, leading to inhibition of c-Myc–induced apoptosis. Therapeutic strategies could be developed to activate this intrinsic apoptotic activity of c-Myc to inhibit tumorigenesis. PMID:23277542

  11. Alternative translation of the proto-oncogene c-myc by an internal ribosome entry site.

    Science.gov (United States)

    Nanbru, C; Lafon, I; Audigier, S; Gensac, M C; Vagner, S; Huez, G; Prats, A C

    1997-12-19

    The human proto-oncogene c-myc encodes two proteins, c-Myc1 and c-Myc2, from two initiation codons, CUG and AUG, respectively. It is also transcribed from four alternative promoters (P0, P1, P2, and P3), giving rise to different RNA 5'-leader sequences, the long sizes of which suggest that they must be inefficiently translated by the classical ribosome scanning mechanism. Here we have examined the influence of three c-myc mRNA 5'-leaders on the translation of chimeric myc-CAT mRNAs. We observed that in the reticulocyte rabbit lysate, these 5'-leaders lead to cap-independent translation initiation. To determine whether this kind of initiation resulted from the presence of an internal ribosome entry site (IRES), COS-7 cells were transfected with bicistronic vectors containing the different c-myc 5'-leaders in the intercistronic region. An IRES was identified, requiring elements located within the P2 leader, between nucleotides -363 and -94 upstream from the CUG start codon. This is the first demonstration of the existence of IRES-dependent translation for a proto-oncogene. This IRES could be a translation enhancer, allowing activation of c-myc expression under the control of trans-acting factors and in response to specific cell stimuli.

  12. Regulation of human ornithine decarboxylase expression by the c-Myc.Max protein complex.

    Science.gov (United States)

    Peña, A; Reddy, C D; Wu, S; Hickok, N J; Reddy, E P; Yumet, G; Soprano, D R; Soprano, K J

    1993-12-25

    The presence of a CACGTG element within a region of the human ornithine decarboxylase (ODC) promoter located at -491 to -474 base pairs 5' to the start site of transcription suggested that the c-Myc.Max protein complex may play a role in the regulation of ODC expression during growth. Electrophoretic mobility shift assays and methylation interference analysis showed that the nuclei of WI-38 cells expressing ODC contained proteins that bound to this region of the ODC gene in a manner that correlated with growth-associated ODC expression. Also, use of antibodies against c-Myc and Max and purified recombinant c-Myc and Max protein in the electrophoretic mobility shift assay confirmed that these proteins can specifically bind this portion of the human ODC promoter. Transient transfection studies showed that increase in the level of c-Myc and/or Max led to a significant enhancement of expression of a human ODC promoter-CAT reporter construct. Moreover, treatment of actively growing WI-38 cells with an antisense oligomer to c-Myc reduced the amount of endogenous protein complex formed and the amount of endogenous ODC mRNA expressed. These studies show that the c-Myc.Max protein complex plays a role in the transcriptional regulation of human ODC in vivo.

  13. ADA3 regulates normal and tumor mammary epithelial cell proliferation through c-MYC.

    Science.gov (United States)

    Griffin, Nicolas I; Sharma, Gayatri; Zhao, Xiangshan; Mirza, Sameer; Srivastava, Shashank; Dave, Bhavana J; Aleskandarany, Mohammed; Rakha, Emad; Mohibi, Shakur; Band, Hamid; Band, Vimla

    2016-11-16

    We have established the critical role of ADA3 as a coactivator of estrogen receptor (ER), as well as its role in cell cycle progression. Furthermore, we showed that ADA3 is predominantly nuclear in mammary epithelium, and in ER+, but is cytoplasmic in ER- breast cancers, the latter correlating with poor survival. However, the role of nuclear ADA3 in human mammary epithelial cells (hMECs), and in ER+ breast cancer cells, as well as the importance of ADA3 expression in relation to patient prognosis and survival in ER+ breast cancer have remained uncharacterized. We overexpressed ADA3 in hMECs or in ER+ breast cancer cells and assessed the effect on cell proliferation. The expression of ADA3 was analyzed then correlated with the expression of various prognostic markers, as well as survival of breast cancer patients. Overexpression of ADA3 in ER- hMECs as well as in ER+ breast cancer cell lines enhanced cell proliferation. These cells showed increased cyclin B and c-MYC, decreased p27 and increased SKP2 levels. This was accompanied by increased mRNA levels of early response genes c-FOS, EGR1, and c-MYC. Analysis of breast cancer tissue specimens showed a significant correlation of ADA3 nuclear expression with c-MYC expression. Furthermore, nuclear ADA3 and c-MYC expression together showed significant correlation with tumor grade, mitosis, pleomorphism, NPI, ER/PR status, Ki67 and p27 expression. Importantly, within ER+ cases, expression of nuclear ADA3 and c-MYC also significantly correlated with Ki67 and p27 expression. Univariate Kaplan Meier analysis of four groups in the whole, as well as the ER+ patients showed that c-MYC and ADA3 combinatorial phenotypes showed significantly different breast cancer specific survival with c-MYC-high and ADA3-Low subgroup had the worst outcome. Using multivariate analyses within the whole cohort and the ER+ subgroups, the significant association of ADA3 and c-MYC expression with patients' outcome was independent of tumor grade

  14. c-Myc is a novel target of cell cycle arrest by honokiol in prostate cancer cells

    Science.gov (United States)

    Hahm, Eun-Ryeong; Singh, Krishna Beer; Singh, Shivendra V.

    2016-01-01

    ABSTRACT Honokiol (HNK), a highly promising phytochemical derived from Magnolia officinalis plant, exhibits in vitro and in vivo anticancer activity against prostate cancer but the underlying mechanism is not fully clear. This study was undertaken to delineate the role of c-Myc in anticancer effects of HNK. Exposure of prostate cancer cells to plasma achievable doses of HNK resulted in a marked decrease in levels of total and/or phosphorylated c-Myc protein as well as its mRNA expression. We also observed suppression of c-Myc protein in PC-3 xenografts upon oral HNK administration. Stable overexpression of c-Myc in PC-3 and 22Rv1 cells conferred significant protection against HNK-mediated growth inhibition and G0-G1 phase cell cycle arrest. HNK treatment decreased expression of c-Myc downstream targets including Cyclin D1 and Enhancer of Zeste Homolog 2 (EZH2), and these effects were partially restored upon c-Myc overexpression. In addition, PC-3 and DU145 cells with stable knockdown of EZH2 were relatively more sensitive to growth inhibition by HNK compared with control cells. Finally, androgen receptor overexpression abrogated HNK-mediated downregulation of c-Myc and its targets particularly EZH2. The present study indicates that c-Myc, which is often overexpressed in early and late stages of human prostate cancer, is a novel target of prostate cancer growth inhibition by HNK. PMID:27341160

  15. c-Myc is a novel target of cell cycle arrest by honokiol in prostate cancer cells.

    Science.gov (United States)

    Hahm, Eun-Ryeong; Singh, Krishna Beer; Singh, Shivendra V

    2016-09-01

    Honokiol (HNK), a highly promising phytochemical derived from Magnolia officinalis plant, exhibits in vitro and in vivo anticancer activity against prostate cancer but the underlying mechanism is not fully clear. This study was undertaken to delineate the role of c-Myc in anticancer effects of HNK. Exposure of prostate cancer cells to plasma achievable doses of HNK resulted in a marked decrease in levels of total and/or phosphorylated c-Myc protein as well as its mRNA expression. We also observed suppression of c-Myc protein in PC-3 xenografts upon oral HNK administration. Stable overexpression of c-Myc in PC-3 and 22Rv1 cells conferred significant protection against HNK-mediated growth inhibition and G0-G1 phase cell cycle arrest. HNK treatment decreased expression of c-Myc downstream targets including Cyclin D1 and Enhancer of Zeste Homolog 2 (EZH2), and these effects were partially restored upon c-Myc overexpression. In addition, PC-3 and DU145 cells with stable knockdown of EZH2 were relatively more sensitive to growth inhibition by HNK compared with control cells. Finally, androgen receptor overexpression abrogated HNK-mediated downregulation of c-Myc and its targets particularly EZH2. The present study indicates that c-Myc, which is often overexpressed in early and late stages of human prostate cancer, is a novel target of prostate cancer growth inhibition by HNK.

  16. Overexpression of c-myc induces epithelial mesenchymal transition in mammary epithelial cells.

    Science.gov (United States)

    Cho, Kyoung Bin; Cho, Min Kyong; Lee, Won Young; Kang, Keon Wook

    2010-07-28

    The c-myc gene is frequently overexpressed in human breast cancer and its target genes are involved in tumorigenesis. Epithelial mesenchymal transitions (EMT), where cells undergo a developmental switch from a polarized epithelial phenotype to a highly motile mesenchymal phenotype, are associated with invasion and motility of cancer cells. Basal E-cadherin expression was down-regulated in c-myc overexpressing MCF10A (c-myc-MCF10A) cells compared to GFP-overexpressing MCF10A (GFP-MCF10A) cells, while N-cadherin was distinctly increased in c-myc-MCF10A cells. Given that glycogen synthase kinase-3beta (GSK-3beta) and the snail axis have key roles in E-cadherin deregulation during EMT, we investigated the role of GSK-3beta/snail signaling pathways in the induction of EMT by c-myc overexpression. In contrast to GFP-MCF10A cells, both the transcriptional activity and the ubiquitination-dependent protein stability of snail were enhanced in c-myc-MCF10A cells, and this was reversed by GSK-3beta overexpression. We also found that c-myc overexpression inhibits GSK-3beta activity through activation of extracellular signal-regulated kinase (ERK). Inhibition of ERK by dominant negative mutant transfection or chemical inhibitor significantly suppressed snail gene transcription. These results suggest that c-myc overexpression during transformation of mammary epithelial cells (MEC) is involved in EMTs via ERK-dependent GSK-3beta inactivation and subsequent snail activation.

  17. A therapeutic role for targeting c-Myc/Hif-1-dependent signaling pathways.

    Science.gov (United States)

    Podar, Klaus; Anderson, Kenneth C

    2010-05-01

    Deregulated c-Myc occurs in approximately 30% of human cancers. Similarly, hypoxia-inducible factor (HIF) is commonly overexpressed in a variety of human malignancies. Under physiologic conditions, HIF inhibits c-Myc activity; however, when deregulated oncogenic c-Myc collaborates with HIF in inducing the expression of VEGF, PDK1 and hexokinase 2. Most of the knowledge of HIF derives from studies investigating a role of HIF under hypoxic conditions, however, HIF-1alpha stabilization is also found in normoxic conditions. Specifically, under hypoxic conditions HIF-1-mediated regulation of oncogenic c-Myc plays a pivotal role in conferring metabolic advantages to tumor cells as well as adaptation to the tumorigenic micromilieu. In addition, our own results show that under normoxic conditions oncogenic c-Myc is required for constitutive high HIF-1 protein levels and activity in Multiple Myeloma (MM) cells, thereby influencing VEGF secretion and angiogenic activity within the bone marrow microenvironment. Further studies are needed to delineate the functional relevance of HIF, MYC, and the HIF-MYC collaboration in MM and other malignancies, also integrating the tumor microenvironment and the cellular context. Importantly, early studies already demonstrate promising preclinical of novel agents, predominantly small molecules, which target c-Myc, HIF or both.

  18. SMARCAL1 Negatively Regulates C-Myc Transcription By Altering The Conformation Of The Promoter Region.

    Science.gov (United States)

    Sharma, Tapan; Bansal, Ritu; Haokip, Dominic Thangminlen; Goel, Isha; Muthuswami, Rohini

    2015-12-09

    SMARCAL1, a member of the SWI2/SNF2 protein family, stabilizes replication forks during DNA damage. In this manuscript, we provide the first evidence that SMARCAL1 is also a transcriptional co-regulator modulating the expression of c-Myc, a transcription factor that regulates 10-15% genes in the human genome. BRG1, SMARCAL1 and RNAPII were found localized onto the c-myc promoter. When HeLa cells were serum starved, the occupancy of SMARCAL1 on the c-myc promoter increased while that of BRG1 and RNAPII decreased correlating with repression of c-myc transcription. Using Active DNA-dependent ATPase A Domain (ADAAD), the bovine homolog of SMARCAL1, we show that the protein can hydrolyze ATP using a specific region upstream of the CT element of the c-myc promoter as a DNA effector. The energy, thereby, released is harnessed to alter the conformation of the promoter DNA. We propose that SMARCAL1 negatively regulates c-myc transcription by altering the conformation of its promoter region during differentiation.

  19. Suppression of RNA interference on expression of c-myc of SKOV3 ovarian carcinoma cell line.

    Science.gov (United States)

    Ai, Z-H; Wang, J; Xu, Y-L; Zhu, X-L; Teng, Y-C

    2013-11-01

    To investigate suppression of RNA interference (RNAi) on expression of c-myc of SKOV3 ovarian carcinoma cell line. The c-myc -siRNA was designed and synthesized, then transfected to SKOV3 ovarian carcinoma cell lines. The cell lines were divided into four groups, including the blank control group, the siRNA transfection group, the mock transfection group and the negative control group. The expression level of c-myc mRNA and protein were detected by RT-PCR and Western blotting, respectively. The growth and proliferation of SKOV3 ovarian carcinoma cell lines were observed with CCK-8 assay. After transfected with c-myc -siRNA, the expression level of c-myc mRNA and protein were down-regulated, the growth and proliferation of SKOV3 ovarian carcinoma cell line were inhibited in the siRNA transfection group. There were significant differences between the siRNA transfection group and the blank control group (p c-myc expression of SKOV3 ovarian carcinoma cell line by c-myc -siRNA can lead to the suppression of cancer cell proliferation. The small interfering RNAs technique can inhibit the proliferation of carcinoma cell by oncogene silencing.

  20. Changes in the phenotype of human small cell lung cancer cell lines after transfection and expression of the c-myc proto-oncogene.

    Science.gov (United States)

    Johnson, B E; Battey, J; Linnoila, I; Becker, K L; Makuch, R W; Snider, R H; Carney, D N; Minna, J D

    1986-01-01

    Small cell lung cancer growing in cell culture possesses biologic properties that allow classification into two categories: classic and variant. Compared with classic small cell lung cancer cell lines, variant lines have altered large cell morphology, shorter doubling times, higher cloning efficiencies in soft agarose, and very low levels of L dopa decarboxylase production and bombesin-like immunoreactivity. C-myc is amplified and expressed in some small cell lung cancer cell lines and all c-myc amplified lines studied to date display the variant phenotype. To investigate if c-myc amplification and expression is responsible for the variant phenotype, a normal human c-myc gene was transfected into a cloned classic small cell lung cancer cell line not amplified for or expressing detectable c-myc messenger RNA (mRNA). Clones were isolated with one to six copies of c-myc stably integrated into DNA that expressed c-myc mRNA. In addition, one clone with an integrated neo gene but a deleted c-myc gene was isolated and in this case c-myc was not expressed. C-myc expression in transfected clones was associated with altered large cell morphology, a shorter doubling time, and increased cloning efficiency, but no difference in L dopa decarboxylase levels and bombesin-like immunoreactivity. We conclude increased c-myc expression observed here in transfected clones correlates with some of the phenotypic properties distinguishing c-myc amplified variants from unamplified classic small cell lung cancer lines. Images PMID:3016030

  1. C-MYC aberrations as prognostic factors in diffuse large B-cell lymphoma: a meta-analysis of epidemiological studies.

    Science.gov (United States)

    Zhou, Kuangguo; Xu, Danmei; Cao, Yang; Wang, Jue; Yang, Yunfan; Huang, Mei

    2014-01-01

    Various studies have investigated the prognostic value of C-MYC aberrations in diffuse large B-cell lymphoma (DLBCL). However, the role of C-MYC as an independent prognostic factor in clinical practice remains controversial. A systematic review and meta-analysis were performed to clarify the clinical significance of C-MYC aberrations in DLBCL patients. The pooled hazard ratios (HRs) for overall survival (OS) and event-free survival (EFS) were calculated as the main effect size estimates. The procedure was conducted according to the Cochrane handbook and PRISMA guidelines, including the use of a heterogeneity test, publication bias assessment, and meta-regression, as well as subgroup analyses. Twenty-four eligible studies enrolling 4662 patients were included in this meta-analysis. According to the nature of C-MYC aberrations (gene, protein, and mRNA), studies were divided into several subgroups. For DLBCL patients with C-MYC gene abnormalities, the combined HR was 2.22 (95% confidence interval, 1.89 to 2.61) for OS and 2.29 (95% confidence interval, 1.81 to 2.90) for EFS, compared to patients without C-MYC gene abnormalities. For DLBCL patients with overexpression of C-MYC protein and C-MYC mRNA, pooled HRs for OS were 2.13 and 1.62, respectively. C-MYC aberrations appeared to play an independent role among other well-known prognostic factors in DLBCL. Addition of rituximab could not overcome the inferior prognosis conferred by C-MYC. The present systematic review and meta-analysis confirm the prognostic value of C-MYC aberrations. Screening of C-MYC should have definite prognostic meaning for DLBCL stratification, thus guaranteeing a more tailored therapy.

  2. Role of Pirh2 in mediating the regulation of p53 and c-Myc.

    Directory of Open Access Journals (Sweden)

    Anne Hakem

    2011-11-01

    Full Text Available Ubiquitylation is fundamental for the regulation of the stability and function of p53 and c-Myc. The E3 ligase Pirh2 has been reported to polyubiquitylate p53 and to mediate its proteasomal degradation. Here, using Pirh2 deficient mice, we report that Pirh2 is important for the in vivo regulation of p53 stability in response to DNA damage. We also demonstrate that c-Myc is a novel interacting protein for Pirh2 and that Pirh2 mediates its polyubiquitylation and proteolysis. Pirh2 mutant mice display elevated levels of c-Myc and are predisposed for plasma cell hyperplasia and tumorigenesis. Consistent with the role p53 plays in suppressing c-Myc-induced oncogenesis, its deficiency exacerbates tumorigenesis of Pirh2(-/- mice. We also report that low expression of human PIRH2 in lung, ovarian, and breast cancers correlates with decreased patients' survival. Collectively, our data reveal the in vivo roles of Pirh2 in the regulation of p53 and c-Myc stability and support its role as a tumor suppressor.

  3. Shikonin regulates C-MYC and GLUT1 expression through the MST1-YAP1-TEAD1 axis.

    Science.gov (United States)

    Vališ, Karel; Talacko, Pavel; Grobárová, Valéria; Černý, Jan; Novák, Petr

    2016-12-10

    The general mechanism underlying the tumor suppressor activity of the Hippo signaling pathway remains unclear. In this study, we explore the molecular mechanisms connecting the Hippo signaling pathway with glucose metabolism. We have found that two key regulators of glycolysis, C-MYC and GLUT1, are targets of the Hippo signaling pathway in human leukemia cells. Our results revealed that activation of MST1 by the natural compound shikonin inhibited the expression of GLUT1 and C-MYC. Furthermore, RNAi experiments confirmed the regulation of GLUT1 and C-MYC expression via the MST1-YAP1-TEAD1 axis. Surprisingly, YAP1 was found to positively regulate C-MYC mRNA levels in complex with TEAD1, while it negatively regulates C-MYC levels in cooperation with MST1. Hence, YAP1 serves as a rheostat for C-MYC, which is regulated by MST1. In addition, depletion of MST1 stimulates lactate production, whereas the specific depletion of TEAD1 has an opposite effect. The inhibition of lactate production and cellular proliferation induced by shikonin also depends on the Hippo pathway activity. Finally, a bioinformatic analysis revealed conserved TEAD-binding motifs in the C-MYC and GLUT1 promoters providing another molecular data supporting our observations. In summary, regulation of glucose metabolism could serve as a new tumor suppressor mechanism orchestrated by the Hippo signaling pathway. Copyright © 2016 Elsevier Inc. All rights reserved.

  4. Expression of c-myc during differentiation of the human teratocarcinoma cell line Tera-2.

    Science.gov (United States)

    Schofield, P N; Engstrom, W; Lee, A J; Biddle, C; Graham, C F

    1987-08-01

    The quantity of c-myc mRNA was measured during the retinoic-acid-induced differentiation of the pluripotent human teratoma cell line, Tera-2 cl. 13. As the cells were exposed to retinoic acid for longer periods of time the duration of the cell cycle progressively increased (measured by the rate of S phase entry) until the cells were effectively quiescent and expressed characteristic differentiation markers. Under these circumstances steady-state levels of c-myc expression increased by up to 1.6-fold with respect to rapidly growing undifferentiated cells. Southern blot analysis of the c-myc genes in Tera-2 indicated no major rearrangement or amplification in the cell line.

  5. Preparation and evaluation of nanoparticles loading plasmid DNAs inserted with siRNA fragments targeting c-Myc gene.

    Science.gov (United States)

    Ma, Tao; Jiang, Jin-Ling; Liu, Ying; Ye, Zheng-Bao; Zhang, Jun

    2014-09-01

    c-Myc plays a key role in glioma cancer stem cell maintenance. A drug delivery system, nanoparticles loading plasmid DNAs inserted with siRNA fragments targeting c-Myc gene (NPs-c-Myc-siRNA-pDNAs), for the treatment of glioma, has not previously been reported. NPs-c-Myc-siRNA-pDNAs were prepared and evaluated in vitro. Three kinds of c-Myc-siRNA fragments were separately synthesized and linked with empty siRNA expression vectors in the mole ratio of 3:1 by T4 DNA ligase. The linked products were then separately transfected into Escherichia coli. DH5α followed by extraction with Endofree plasmid Mega kit (Qiagen, Hilden, Germany) obtained c-Myc-siRNA-pDNAs. Finally, the recombinant c-Myc-siRNA3-pDNAs, generating the highest transfection efficiency and the greatest apoptotic ability, were chosen for encapsulation into NPs by the double-emulsion solvent-evaporation procedure, followed by stability, transfection efficiency, as well as qualitative and quantitative apoptosis evaluation. NPs-c-Myc-siRNA3-pDNAs were obtained with spherical shape in uniform size below 150 nm, with the zeta potential about -18 mV, the encapsulation efficiency and loading capacity as 76.3 ± 5.4% and 1.91 ± 0.06%, respectively. The stability results showed that c-Myc-siRNA3-pDNAs remained structurally and functionally stable after encapsulated into NPs, and NPs could prevent the loaded c-Myc-siRNA3-pDNAs from DNase degradation. The transfection efficiency of NPs-c-Myc-siRNA3-pDNAs was proven to be positive. Furthermore, NPs-c-Myc-siRNA3-pDNAs produced significant apoptosis with the apoptotic rate at 24.77 ± 5.39% and early apoptosis cells observed. Methoxy-poly-(ethylene-glycol)-poly-(lactide-co-glycolide) nanoparticles (MPEG-PLGA-NPs) are potential delivery carriers for c-Myc-siRNA3-pDNAs.

  6. c-myc null cells misregulate cad and gadd45 but not other proposed c-Myc targets

    Science.gov (United States)

    Bush, Andrew; Mateyak, Maria; Dugan, Kerri; Obaya, Alvaro; Adachi, Susumu; Sedivy, John; Cole, Michael

    1998-01-01

    We report here that the expression of virtually all proposed c-Myc target genes is unchanged in cells containing a homozygous null deletion of c-myc. Two noteworthy exceptions are the gene cad, which has reduced log phase expression and serum induction in c-myc null cells, and the growth arrest gene gadd45, which is derepressed by c-myc knockout. Thus, cad and gadd45 are the only proposed targets of c-Myc that may contribute to the dramatic slow growth phenotype of c-myc null cells. Our results demonstrate that a loss-of-function approach is critical for the evaluation of potential c-Myc target genes. PMID:9869632

  7. Aspirin and salicylic acid decrease c-Myc expression in cancer cells: a potential role in chemoprevention.

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    Ai, Guoqiang; Dachineni, Rakesh; Muley, Pratik; Tummala, Hemachand; Bhat, G Jayarama

    2016-02-01

    Epidemiological studies have demonstrated a significant correlation between regular aspirin use and reduced colon cancer incidence and mortality; however, the pathways by which it exerts its anti-cancer effects are still not fully explored. We hypothesized that aspirin's anti-cancer effect may occur through downregulation of c-Myc gene expression. Here, we demonstrate that aspirin and its primary metabolite, salicylic acid, decrease the c-Myc protein levels in human HCT-116 colon and in few other cancer cell lines. In total cell lysates, both drugs decreased the levels of c-Myc in a concentration-dependent fashion. Greater inhibition was observed in the nucleus than the cytoplasm, and immunofluorescence studies confirmed these observations. Pretreatment of cells with lactacystin, a proteasome inhibitor, partially prevented the downregulatory effect of both aspirin and salicylic acid, suggesting that 26S proteasomal pathway is involved. Both drugs failed to decrease exogenously expressed DDK-tagged c-Myc protein levels; however, under the same conditions, the endogenous c-Myc protein levels were downregulated. Northern blot analysis showed that both drugs caused a decrease in c-Myc mRNA levels in a concentration-dependent fashion. High-performance liquid chromatography (HPLC) analysis showed that aspirin taken up by cells was rapidly metabolized to salicylic acid, suggesting that aspirin's inhibitory effect on c-Myc may occur through formation of salicylic acid. Our result suggests that salicylic acid regulates c-Myc level at both transcriptional and post-transcription levels. Inhibition of c-Myc may represent an important pathway by which aspirin exerts its anti-cancer effect and decrease the occurrence of cancer in epithelial tissues.

  8. Stabilization of c-myc G-Quadruplex DNA, inhibition of telomerase activity, disruption of mitochondrial functions and tumor cell apoptosis by platinum(II) complex with 9-amino-oxoisoaporphine.

    Science.gov (United States)

    Qin, Jiao-Lan; Qin, Qi-Pin; Wei, Zu-Zhuang; Yu, Yan-Cheng; Meng, Ting; Wu, Chen-Xuan; Liang, Yue-Lan; Liang, Hong; Chen, Zhen-Feng

    2016-11-29

    [Pd(L)(DMSO)Cl2] (1) and [Pt(L)(DMSO)Cl2] (2) with 9-amino-oxoisoaporphine (L), were synthesized and characterized. 1 and 2 are more selectively cytotoxic to Hep-G2 cells versus normal liver cells (HL-7702). Various experiments showed that 2 acted as telomerase inhibitors targeting G4-DNA and triggered cell apoptosis by interacting with c-myc G4-DNA. Furthermore, 2 significantly induced cell cycle arrest at both G2/M and S phase, which leading to the down-regulation of cdc25 A, cyclin D, cyclin B, cyclin A and CDK2 and the up-regulation of p53, p27, p21,chk1 and chk2. In addition, 2 also caused mitochondrial dysfunction. Taken together, we found that 2 exerted its cytotoxic activity mainly via inhibiting telomerase by interaction with c-myc G4-DNA and disruption of mitochondrial function.

  9. c-MYC expression sensitizes medulloblastoma cells to radio- and chemotherapy and has no impact on response in medulloblastoma patients

    Science.gov (United States)

    2011-01-01

    Background To study whether and how c-MYC expression determines response to radio- and chemotherapy in childhood medulloblastoma (MB). Methods We used DAOY and UW228 human MB cells engineered to stably express different levels of c-MYC, and tested whether c-MYC expression has an effect on radio- and chemosensitivity using the colorimetric 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium inner salt (MTS) assay, clonogenic survival, apoptosis assays, cell cycle analysis, and western blot assessment. In an effort to validate our results, we analyzed c-MYC mRNA expression in formalin-fixed paraffin-embedded tumor samples from well-documented patients with postoperative residual tumor and compared c-MYC mRNA expression with response to radio- and chemotherapy as examined by neuroradiological imaging. Results In DAOY - and to a lesser extent in UW228 - cells expressing high levels of c-MYC, the cytotoxicity of cisplatin, and etoposide was significantly higher when compared with DAOY/UW228 cells expressing low levels of c-MYC. Irradiation- and chemotherapy-induced apoptotic cell death was enhanced in DAOY cells expressing high levels of c-MYC. The response of 62 of 66 residual tumors was evaluable and response to postoperative radio- (14 responders (CR, PR) vs. 5 non-responders (SD, PD)) or chemotherapy (23 CR/PR vs. 20 SD/PD) was assessed. c-MYC mRNA expression was similar in primary MB samples of responders and non-responders (Mann-Whitney U test, p = 0.50, ratio 0.49, 95% CI 0.008-30.0 and p = 0.67, ratio 1.8, 95% CI 0.14-23.5, respectively). Conclusions c-MYC sensitizes MB cells to some anti-cancer treatments in vitro. As we failed to show evidence for such an effect on postoperative residual tumors when analyzed by imaging, additional investigations in xenografts and larger MB cohorts may help to define the exact function of c-MYC in modulating response to treatment. PMID:21324178

  10. A circular RNA promotes tumorigenesis by inducing c-myc nuclear translocation.

    Science.gov (United States)

    Yang, Qi; Du, William W; Wu, Nan; Yang, Weining; Awan, Faryal Mehwish; Fang, Ling; Ma, Jian; Li, Xiangmin; Zeng, Yan; Yang, Zhenguo; Dong, Jun; Khorshidi, Azam; Yang, Burton B

    2017-09-01

    Circular RNAs (circRNAs) are a subclass of noncoding RNAs widely expressed in mammalian cells. We report here the tumorigenic capacity of a circRNA derived from angiomotin-like1 (circ-Amotl1). Circ-Amotl1 is highly expressed in patient tumor samples and cancer cell lines. Single-cell inoculations using circ-Amotl1-transfected tumor cells showed a 30-fold increase in proliferative capacity relative to control. Agarose colony-formation assays similarly revealed a 142-fold increase. Tumor-take rate in nude mouse xenografts using 6-day (219 cells) and 3-day (9 cells) colonies were 100%, suggesting tumor-forming potential of every cell. Subcutaneous single-cell injections led to the formation of palpable tumors in 41% of mice, with tumor sizes >1 cm(3) in 1 month. We further found that this potent tumorigenicity was triggered through interactions between circ-Amotl1 and c-myc. A putative binding site was identified in silico and tested experimentally. Ectopic expression of circ-Amotl1 increased retention of nuclear c-myc, appearing to promote c-myc stability and upregulate c-myc targets. Expression of circ-Amotl1 also increased the affinity of c-myc binding to a number of promoters. Our study therefore reveals a novel function of circRNAs in tumorigenesis, and this subclass of noncoding RNAs may represent a potential target in cancer therapy.

  11. A proteomic study of cMyc improvement of CHO culture

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    Dunn Michael J

    2010-03-01

    Full Text Available Abstract Background The biopharmaceutical industry requires cell lines to have an optimal proliferation rate and a high integral viable cell number resulting in a maximum volumetric recombinant protein product titre. Nutrient feeding has been shown to boost cell number and productivity in fed-batch culture, but cell line engineering is another route one may take to increase these parameters in the bioreactor. The use of CHO-K1 cells with a c-myc plasmid allowing for over-expressing c-Myc (designated cMycCHO gives a higher integral viable cell number. In this study the differential protein expression in cMycCHO is investigated using two-dimensional gel electrophoresis (2-DE followed by image analysis to determine the extent of the effect c-Myc has on the cell and the proteins involved to give the new phenotype. Results Over 100 proteins that were differentially expressed in cMycCHO cells were detected with high statistical confidence, of which 41 were subsequently identified by tandem mass spectrometry (LC-MS/MS. Further analysis revealed proteins involved in a variety of pathways. Some examples of changes in protein expression include: an increase in nucleolin, involved in proliferation and known to aid in stabilising anti-apoptotic protein mRNA levels, the cytoskeleton and mitochondrial morphology (vimentin, protein biosysnthesis (eIF6 and energy metabolism (ATP synthetase, and a decreased regulation of all proteins, indentified, involved in matrix and cell to cell adhesion. Conclusion These results indicate several proteins involved in proliferation and adhesion that could be useful for future approaches to improve proliferation and decrease adhesion of CHO cell lines which are difficult to adapt to suspension culture.

  12. Balance of Yin and Yang: Ubiquitylation-Mediated Regulation of p53 and c-Myc

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    Mu-Shui Dai

    2006-08-01

    Full Text Available Protein ubiquitylation has been demonstrated to play a vital role not only in mediating protein turnover but also in modulating protein activity. The stability and activity of the tumor suppressor p53 and of the oncoprotein c-Myc are no exception. Both are regulated through independent ubiquitylation by several E3 ubiquitin ligases. Interestingly, p53 and c-Myc are functionally connected by some of these E3 enzymes and their regulator ARF, although these proteins play opposite roles in controlling cell growth and proliferation. The balance of this complex ubiquitylation network and its disruption during oncogenesis will be the topics of this review.

  13. Functional analysis of Burkitt's lymphoma mutant c-Myc proteins

    OpenAIRE

    1996-01-01

    The c-myc gene encodes a sequence-specific DNA binding protein that activates transcription of cellular genes. Transcription activation by Myc proteins is regulated by phosphorylation of serine and threonine residues within the transactivation domain and by complex formation with the retinoblastoma-related protein p107. In Burkitt’s lymphoma, missense mutations within the c-Myc transactivation domain have been found with high frequency. It has been reported that mutant c-Myc proteins derived ...

  14. Hepatitis C virus-induced activation of β-catenin promotes c-Myc expression and a cascade of pro-carcinogenetic events.

    Science.gov (United States)

    Higgs, M R; Lerat, H; Pawlotsky, J-M

    2013-09-26

    Chronic infection by hepatitis C virus (HCV) is a major risk factor for the onset and development of hepatocellular carcinoma (HCC), although the underlying mechanisms are unclear. The c-Myc oncogene contributes to the genesis of many types of cancers, including HCC, partly via the induction of genetic damage and the inhibition of the cellular response to genotoxic stress. Here, we show a previously undiscovered mechanistic link between HCV infection and enhanced c-Myc expression. c-Myc expression was augmented in non-tumoral liver tissues from HCV-infected individuals with or without HCC and in hepatocyte cell lines harboring an HCV replicon and the infectious HCV strain JFH1. Increased c-Myc expression was confirmed in vivo in a transgenic murine model expressing the entire HCV open reading frame, demonstrating a direct role for HCV protein expression in c-Myc induction. Mechanistically, activation of Akt by the HCV non-structural protein NS5A, and the subsequent stabilization of the transcription factor β-catenin, was demonstrated to be responsible for activation of the c-Myc promoter, and for increased c-Myc transcription. β-Catenin-dependent c-Myc expression in this context led to increased production of reactive oxygen species, mitochondrial perturbation, enhanced DNA damage and aberrant cell-cycle arrest. Together, these data provide a novel insight into the mechanisms involved in HCV-associated HCCs, strongly suggesting that c-Myc has a crucial contributory role in this process.

  15. c-MYC-Making Liver Sick: Role of c-MYC in Hepatic Cell Function, Homeostasis and Disease.

    Science.gov (United States)

    Zheng, Kang; Cubero, Francisco Javier; Nevzorova, Yulia A

    2017-04-19

    Over 35 years ago, c-MYC, a highly pleiotropic transcription factor that regulates hepatic cell function, was identified. In recent years, a considerable increment in the number of publications has significantly shifted the way that the c-MYC function is perceived. Overexpression of c-MYC alters a wide range of roles including cell proliferation, growth, metabolism, DNA replication, cell cycle progression, cell adhesion and differentiation. The purpose of this review is to broaden the understanding of the general functions of c-MYC, to focus on c-MYC-driven pathogenesis in the liver, explain its mode of action under basal conditions and during disease, and discuss efforts to target c-MYC as a plausible therapy for liver disease.

  16. Fluorescent Dansyl-Guanosine Conjugates that Bind c-MYC Promoter G-Quadruplex and Downregulate c-MYC Expression.

    Science.gov (United States)

    Pavan Kumar, Y; Saha, Puja; Saha, Dhurjhoti; Bessi, Irene; Schwalbe, Harald; Chowdhury, Shantanu; Dash, Jyotirmayee

    2016-03-02

    The four-stranded G-quadruplex present in the c-MYC P1 promoter has been shown to play a pivotal role in the regulation of c-MYC transcription. Small-molecule compounds capable of inhibiting the c-MYC promoter activity by stabilising the c-MYC G-quadruplex could potentially be used as anticancer agents. In this context, here we report the synthesis of dansyl-guanosine conjugates through one-pot modular click reactions. The dansyl-guanosine conjugates can selectively detect c-MYC G-quadruplex over other biologically relevant quadruplexes and duplex DNA and can be useful as staining reagents for selective visualisation of c-MYC G-quadruplex over duplex DNA by gel electrophoresis. NMR spectroscopic titrations revealed the preferential binding sites of these dansyl ligands to the c-MYC G-quadruplex. A dual luciferase assay and qRT-PCR revealed that a dansyl-bisguanosine ligand represses the c-MYC expression, possibly by stabilising the c-MYC G-quadruplex. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. c-MYC-induced genomic instability.

    Science.gov (United States)

    Kuzyk, Alexandra; Mai, Sabine

    2014-04-01

    MYC dysregulation initiates a dynamic process of genomic instability that is linked to tumor initiation. Early studies using MYC-carrying retroviruses showed that these viruses were potent transforming agents. Cell culture models followed that addressed the role of MYC in transformation. With the advent of MYC transgenic mice, it became obvious that MYC deregulation alone was sufficient to initiate B-cell neoplasia in mice. More than 70% of all tumors have some form of c-MYC gene dysregulation, which affects gene regulation, microRNA expression profiles, large genomic amplifications, and the overall organization of the nucleus. These changes set the stage for the dynamic genomic rearrangements that are associated with cellular transformation.

  18. Clinical significance of high c-MYC and low MYCBP2 expression and their association with Ikaros dysfunction in adult acute lymphoblastic leukemia.

    Science.gov (United States)

    Ge, Zheng; Guo, Xing; Li, Jianyong; Hartman, Melanie; Kawasawa, Yuka Imamura; Dovat, Sinisa; Song, Chunhua

    2015-12-01

    Increased expression of c-MYC is observed in both Acute Myeloid Leukemia (AML) and T-cell Acute Lymphoblastic Leukemia (T-ALL). MYC binding protein 2 (MYCBP2) is a probable E3 ubiquitin ligase and its function in leukemia is unknown. IKZF1 deletion is associated with the development and poor outcome of ALL. Here, we observed significant high c-MYC expression and low MYCBP2 expression in adult ALL patients. Patients with high c-MYC expression and/or low MYCBP2 expression had higher WBC counts and a higher percentage of CD34+ or CD33+ cells, as well as splenomegaly, liver infiltration, higher BM blasts, and lower CR rate. Ikaros bound to the regulatory regions of c-MYC and MYCBP2, suppressed c-MYC and increased MYCBP2 expression in ALL cells. Expression of c-MYC mRNA was significantly higher in patients with IKZF1 deletion; conversely MYCBP2 mRNA expression was significantly lower in those patients. A CK2 inhibitor, which acts as an Ikaros activator, also suppressed c-MYC and increased MYCBP2 expression in an Ikaros (IKZF1) dependent manner in the ALL cells. In summary, our data indicated the correlation of high c-MYC expression, low MYCBP2 expression and high c-MYC plus low MYCBP2 expression with high-risk factors and proliferation markers in adult ALL patients. Our data also revealed an oncogenic role for an Ikaros/MYCBP2/c-MYC axis in adult ALL, providing a mechanism of target therapies that activate Ikaros in adult ALL.

  19. c-myc Regulates Cell Proliferation during Lens Development

    Science.gov (United States)

    Gomes, Anielle L.; Rodrigues, Paulo M. G.; Martins, Rodrigo A. P.

    2014-01-01

    Myc protooncogenes play important roles in the regulation of cell proliferation, growth, differentiation and survival during development. In various developing organs, c-myc has been shown to control the expression of cell cycle regulators and its misregulated expression is detected in many human tumors. Here, we show that c-myc gene (Myc) is highly expressed in developing mouse lens. Targeted deletion of c-myc gene from head surface ectoderm dramatically impaired ocular organogenesis, resulting in severe microphtalmia, defective anterior segment development, formation of a lens stalk and/or aphakia. In particular, lenses lacking c-myc presented thinner epithelial cell layer and growth impairment that was detectable soon after its inactivation. Defective development of c-myc-null lens was not caused by increased cell death of lens progenitor cells. Instead, c-myc loss reduced cell proliferation, what was associated with an ectopic expression of Prox1 and p27Kip1 proteins within epithelial cells. Interestingly, a sharp decrease in the expression of the forkhead box transcription factor Foxe3 was also observed following c-myc inactivation. These data represent the first description of the physiological roles played by a Myc family member in mouse lens development. Our findings support the conclusion that c-myc regulates the proliferation of lens epithelial cells in vivo and may, directly or indirectly, modulate the expression of classical cell cycle regulators in developing mouse lens. PMID:24503550

  20. c-Myc regulates cell proliferation during lens development.

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    Gabriel R Cavalheiro

    Full Text Available Myc protooncogenes play important roles in the regulation of cell proliferation, growth, differentiation and survival during development. In various developing organs, c-myc has been shown to control the expression of cell cycle regulators and its misregulated expression is detected in many human tumors. Here, we show that c-myc gene (Myc is highly expressed in developing mouse lens. Targeted deletion of c-myc gene from head surface ectoderm dramatically impaired ocular organogenesis, resulting in severe microphtalmia, defective anterior segment development, formation of a lens stalk and/or aphakia. In particular, lenses lacking c-myc presented thinner epithelial cell layer and growth impairment that was detectable soon after its inactivation. Defective development of c-myc-null lens was not caused by increased cell death of lens progenitor cells. Instead, c-myc loss reduced cell proliferation, what was associated with an ectopic expression of Prox1 and p27(Kip1 proteins within epithelial cells. Interestingly, a sharp decrease in the expression of the forkhead box transcription factor Foxe3 was also observed following c-myc inactivation. These data represent the first description of the physiological roles played by a Myc family member in mouse lens development. Our findings support the conclusion that c-myc regulates the proliferation of lens epithelial cells in vivo and may, directly or indirectly, modulate the expression of classical cell cycle regulators in developing mouse lens.

  1. Transcriptional Amplification in Tumor Cells with Elevated c-Myc

    Science.gov (United States)

    Lin, Charles Y.; Lovén, Jakob; Rahl, Peter B.; Paranal, Ronald M.; Burge, Christopher B.; Bradner, James E.; Lee, Tong Ihn; Young, Richard A.

    2012-01-01

    Summary Elevated expression of the c-Myc transcription factor occurs frequently in human cancers and is associated with tumor aggression and poor clinical outcome. The effect of high levels of c-Myc on global gene regulation is poorly understood, but is widely thought to involve newly activated or repressed “Myc target genes”. We report here that in tumor cells expressing high levels of c-Myc, the transcription factor accumulates in the promoter regions of active genes and causes transcriptional amplification, producing increased levels of transcripts within the cell's gene expression program. Thus, rather than binding and regulating a new set of genes, c-Myc amplifies the output of the existing gene expression program. These results provide an explanation for the diverse effects of oncogenic c-Myc on gene expression in different tumor cells and suggest that transcriptional amplification reduces rate-limiting constraints for tumor cell growth and proliferation. PMID:23021215

  2. Interaction of c-Myc with the pRb-related protein p107 results in inhibition of c-Myc-mediated transactivation

    NARCIS (Netherlands)

    Beijersbergen, R.L.; Hijmans, E.M.; Zhu, L.; Bernards, R.A.

    1994-01-01

    The product of the c-myc proto-oncogene, c-Myc, is a sequence-specific DNA binding protein with an Nterminal transactivation domain and a C-terminal DNA binding domain. Several lines of evidence indicate that c-Myc activity is essential for normal cell cycle progression. Since the abundance of c-Myc

  3. Interaction of c-Myc with the pRb-related protein p107 results in inhibition of c-Myc-mediated transactivation

    NARCIS (Netherlands)

    Beijersbergen, R.L.; Hijmans, E.M.; Zhu, L.; Bernards, R.A.

    1994-01-01

    The product of the c-myc proto-oncogene, c-Myc, is a sequence-specific DNA binding protein with an Nterminal transactivation domain and a C-terminal DNA binding domain. Several lines of evidence indicate that c-Myc activity is essential for normal cell cycle progression. Since the abundance of c-Myc

  4. Discovery of a Family of Genomic Sequences Which Interact Specifically with the c-MYC Promoter to Regulate c-MYC Expression

    Science.gov (United States)

    Thomas, Shelia D.; Rouchka, Eric C.; Miller, Donald M.

    2016-01-01

    G-quadruplex forming sequences are particularly enriched in the promoter regions of eukaryotic genes, especially of oncogenes. One of the most well studied G-quadruplex forming sequences is located in the nuclease hypersensitive element (NHE) III1 of the c-MYC promoter region. The oncoprotein c-MYC regulates a large array of genes which play important roles in growth regulation and metabolism. It is dysregulated in >70% of human cancers. The silencer NHEIII1 located upstream of the P1 promoter regulates up-to 80% of c-MYC transcription and includes a G-quadruplex structure (Pu27) that is required for promoter inhibition. We have identified, for the first time, a family of seventeen G-quadruplex-forming motifs with >90% identity with Pu27, located on different chromosomes throughout the human genome, some found near or within genes involved in stem cell maintenance or neural cell development. Notably, all members of the Pu27 family interact specifically with NHEIII1 sequence, in vitro. Crosslinking studies demonstrate that Pu27 oligonucleotide binds specifically to the C-rich strand of the NHEIII1 resulting in the G-quadruplex structure stabilization. Pu27 homologous sequences (Pu27-HS) significantly inhibit leukemic cell lines proliferation in culture. Exposure of U937 cells to the Pu27-HS induces cell growth inhibition associated with cell cycle arrest that is most likely due to downregulation of c-MYC expression at the RNA and/or protein levels. Expression of SOX2, another gene containing a Pu27-HS, was affected by Pu27-HS treatment as well. Our data suggest that the oligonucleotides encoding the Pu27 family target complementary DNA sequences in the genome, including those of the c-MYC and SOX2 promoters. This effect is most likely cell type and cell growth condition dependent. The presence of genomic G-quadruplex-forming sequences homologous to Pu27 of c-MYC silencer and the fact that they interact specifically with the parent sequence suggest a common

  5. Global regulation of nucleotide biosynthetic genes by c-Myc.

    Directory of Open Access Journals (Sweden)

    Yen-Chun Liu

    Full Text Available BACKGROUND: The c-Myc transcription factor is a master regulator and integrates cell proliferation, cell growth and metabolism through activating thousands of target genes. Our identification of direct c-Myc target genes by chromatin immunoprecipitation (ChIP coupled with pair-end ditag sequencing analysis (ChIP-PET revealed that nucleotide metabolic genes are enriched among c-Myc targets, but the role of Myc in regulating nucleotide metabolic genes has not been comprehensively delineated. METHODOLOGY/PRINCIPAL FINDINGS: Here, we report that the majority of genes in human purine and pyrimidine biosynthesis pathway were induced and directly bound by c-Myc in the P493-6 human Burkitt's lymphoma model cell line. The majority of these genes were also responsive to the ligand-activated Myc-estrogen receptor fusion protein, Myc-ER, in a Myc null rat fibroblast cell line, HO.15 MYC-ER. Furthermore, these targets are also responsive to Myc activation in transgenic mouse livers in vivo. To determine the functional significance of c-Myc regulation of nucleotide metabolism, we sought to determine the effect of loss of function of direct Myc targets inosine monophosphate dehydrogenases (IMPDH1 and IMPDH2 on c-Myc-induced cell growth and proliferation. In this regard, we used a specific IMPDH inhibitor mycophenolic acid (MPA and found that MPA dramatically inhibits c-Myc-induced P493-6 cell proliferation through S-phase arrest and apoptosis. CONCLUSIONS/SIGNIFICANCE: Taken together, these results demonstrate the direct induction of nucleotide metabolic genes by c-Myc in multiple systems. Our finding of an S-phase arrest in cells with diminished IMPDH activity suggests that nucleotide pool balance is essential for c-Myc's orchestration of DNA replication, such that uncoupling of these two processes create DNA replication stress and apoptosis.

  6. Telomerase in relation to expression of p53, c-Myc and estrogen receptor in ovarian tumours

    NARCIS (Netherlands)

    Wisman, GBA; Hollema, H; Helder, MN; Knol, AJ; Van Der Meer, GT; Krans, M; De Jong, S; De Vries, EGE; Van Der Zee, AGJ

    2003-01-01

    Telomerase activity and its subunits (hTERC, hTERT mRNA) were evaluated in ovarian tumours in relation to the expression of p53, c-Myc and estrogen receptor (ER). Furthermore, relations between telomerase activity, hTERC and hTERT with known clinicopathologic prognostic factors and survival in patie

  7. Telomerase in relation to expression of p53, c-Myc and estrogen receptor in ovarian tumours

    NARCIS (Netherlands)

    Wisman, GBA; Hollema, H; Helder, MN; Knol, AJ; Van Der Meer, GT; Krans, M; De Jong, S; De Vries, EGE; Van Der Zee, AGJ

    2003-01-01

    Telomerase activity and its subunits (hTERC, hTERT mRNA) were evaluated in ovarian tumours in relation to the expression of p53, c-Myc and estrogen receptor (ER). Furthermore, relations between telomerase activity, hTERC and hTERT with known clinicopathologic prognostic factors and survival in patie

  8. Suppression of c-Myc enhances p21(WAF1/CIP1) -mediated G1 cell cycle arrest through the modulation of ERK phosphorylation by ascochlorin.

    Science.gov (United States)

    Jeong, Yun-Jeong; Hoe, Hyang-Sook; Cho, Hyun-Ji; Park, Kwan-Kyu; Kim, Dae-Dong; Kim, Cheorl-Ho; Magae, Junji; Kang, Dong Wook; Lee, Sang-Rae; Chang, Young-Chae

    2017-08-18

    Numerous anti-cancer agents inhibit cell cycle progression via a p53-dependent mechanism; however, other genes such as the proto-oncogene c-Myc are promising targets for anticancer therapy. In the present study, we provide evidence that ascochlorin, an isoprenoid antibiotic, is a non-toxic anti-cancer agent that induces G1 cell cycle arrest and p21(WAF1/CIP1) expression by downregulating of c-Myc protein expression. Ascochlorin promoted the G1 arrest, upregulated p53 and p21(WAF1/CIP1) , and downregulated c-Myc in HCT116 cells. In p53-deficient cells, ascochlorin enhanced the expression of G1 arrest-related genes except p53. Small interfering RNA (siRNA) mediated c-Myc silencing indicated that the transcriptional repression of c-Myc was related to ascochlorin-mediated modulation of p21(WAF1/CIP1) expression. Ascochlorin suppressed the stabilization of the c-Myc protein by inhibiting ERK and P70S6K/4EBP1 phosphorylation, whereas it had no effect on c-Myc degradation mediated by PI3K/Akt/GSK3β. The ERK inhibitor PD98059 and siRNA-mediated ERK silencing induced G1 arrest and p21(WAF1/CIP1) expression by downregulating c-Myc in p53-deficient cells. These results indicated that ascochlorin-induced G1 arrest is associated with the repression of ERK phosphorylation and c-Myc expression. Thus, we reveal a role for ascochlorin in inhibiting tumor growth via G1 arrest, and identify a novel regulatory mechanism for ERK /c-Myc. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

  9. Abnormal expression of c-Myc in human bronchial epithelial cells malignantly transformed by anti-BPDE

    Institute of Scientific and Technical Information of China (English)

    Juan FU; Yiguo JIANG; Xuemin CHEN

    2008-01-01

    Anti-benzo[a]pyrene-7,8-diol-9,10-epoxide (anti-BPDE) is a metabolite of benzo[a]pyrene (B[a] P) and acts as a potent mutagen in mammalian systems. However, molecular mechanisms related to anti-BPDE-induced carcinogenesis are poorly understood. Here, we investigated the expression of proto-oncogene c-myc in human bronchial epithelial cells (16H BE-T) transformed by exposure to anti-BPDE. The levels ofmRNA and pro-tein of c-M yc were examined in the 16HBE-T and vehicle-treated control cells (16HBE-N) by using different meth-ods respectively, including reverse transcriptase-polymer-ase chain reaction (RT-PCR), quantitative real-time PCR (Q-PCR), western blot and immunocytochemical meth-ods. The level of c-myc mRNA appeared to be signifi-cantly increased in 16HBE-T, as compared with those of the 16H BE-N. Likewise, the expression of c-Myc protein was significantly enhanced as compared with those of the control cells. Moreover, the localization of c-Myc protein shows mainly nuclear staining in 16HBE-T. In conclu-sion, the abnormal expression of c-Myc was present in anti-BPDE malignantly transformed 16HBE cells, which may be involved in the carcinogenesis molecular mech-anism of anti-BPDE.

  10. c-Myc-Induced Extrachromosomal Elements Carry Active Chromatin

    Directory of Open Access Journals (Sweden)

    Greg Smith

    2003-03-01

    Full Text Available Murine Pre-13 lymphocytes with experimentally activated MycER show both chromosomal and extrachromosomal gene amplification. In this report, we have elucidated the size, structure, functional components of c-Myc-induced extrachromosomal elements (EEs. Scanning electron microscopy revealed that EEs isolated from MycER-activated Pre-B+ cells are an average of 10 times larger than EEs isolated from non-MycER-activated control Pre-B- cells. We demonstrate that these large c-Myc-induced EEs are associated with histone proteins, whereas EEs of non-MycER-activated Pre B- cells are not. Immunohistochemistry and Western blot analyses using pan -histone-specific, histone H3 phosphorylation-specific, histone H4 acetylation-specific antibodies indicate that a significant proportion of EEs analyzed from MycER-activated cells harbors transcriptionally competent and/or active chromatin. Moreover, these large, c-Myc-induced EEs carry genes. Whereas the total genetic make-up of these c-Myc-induced EEs is unknown, we found that 30.2% of them contain the dihydrofolate reductase (DHFR gene, whereas cyclin C (CCNC was absent. In addition, 50% of these c-Myc-activated Pre-B+ EEs incorporated bromodeoxyuridine (BrdU, identifying them as genetic structures that self-propagate. In contrast, EEs isolated from non-Myc-activated cells neither carry the DHFR gene nor incorporate BrdU, suggesting that c-Myc deregulation generates a new class of EEs.

  11. Use of a transfected and amplified Drosophila heat shock promoter construction for inducible production of toxic mouse c-myc proteins in CHO cells

    Energy Technology Data Exchange (ETDEWEB)

    Wurm, F.M.; Gwinn, K.A.; Papoulas, O.; Pallavicini, M.; Kingston, R.E.

    1987-07-24

    After transfection and selection with methotrexate, CHO cell lines were established which contained up to 2000 copies of an expression vector for c-myc protein. The vector contained the Drosophila heat shock protein 70 (hsp70) promoter fused with the coding region of the mouse c-myc gene. Incubation of cells for up to 3 hours at 43/sup 0/C resulted in at least a 100-fold induction of recombinant c-myc mRNA. When cells were shifted back to 37/sup 0/C, within 1 to 4 hours, this RNA was translated into protein to yield about 250 ..mu..g per 10/sup 9/ cells. Cells died a few hours later, suggesting that high concentrations of intracellular c-myc are cytotoxic. 47 refs., 5 figs.

  12. CT120: A New Potential Target for c-Myc in Head and Neck Cancers.

    Science.gov (United States)

    Baltaci, Elif; Seyhan, Betül; Baykara, Onur; Buyru, Nur

    2017-01-01

    Background: CT120 is a universally expressed protein with seven transmembrane domains. It functions in cell proliferation, survival and apoptosis by activating Raf/MEK/ERK and PI3K/Akt signaling pathways. Evidence suggests that CT120 plays important roles in lung carcinogenesis and oncogenic pathway activation. c-Myc is an important transcription factor modulating cell progression, apoptosis and cellular transformation. Previous studies have shown that MYC gene is amplified in many types of cancer including head and neck squamous cell carcinoma (HNSCC). Myc can regulate expression of many genes by binding to E-boxes. The aim of this study was to investigate the relationship between c-Myc protein and CT120 gene. Methods: Tumor and normal tissue samples from 50 patients with HNSCC were investigated with chromatin immunoprecipitation assay (ChIP), Illumina MiSeq, bisulphite sequencing and qRT-PCR. Results: c-Myc binds to all E-boxes except E-box 5 on CT120 promoter. The CpG dinucleotides were found to be partially methylated in all tumor and normal tissue samples. Bisulphite sequencing showed a 10% down-regulation in the methylation levels of the tumor tissues. CT120 gene was hypomethylated and up-regulated in 56% of the tumor tissue samples. Expression of c-Myc was significantly higher in tumor tissues than in non-cancerous tissue samples. MYC was overexpressed in 68% of the tumor tissue samples compared to normal tissues. The mean MYC levels were 2.42-fold higher in the tumor tissue samples. In 48% of the tumor tissues, MYC and CT120A mRNA were up- or down-regulated simultaneously (pc-Myc and it contributes to cancer progression in HNSCC.

  13. cDNA-library testing identifies transforming genes cooperating with c-myc in mouse pre-B cells.

    Science.gov (United States)

    Wolf, Inge; Bouquet, Corinne; Melchers, Fritz

    2016-11-01

    While c-myc often contributes to the generation of B cell transformation, its transgenic overexpression alone does not lead to full transformation of B-lineage cells. Synergistically acting second genes must cooperate. Here, we constructed doxycycline-inducible cDNA-libraries from pre-B cell mRNA. These libraries were retrovirally transduced as single copies into single cells and overexpressed in fetal-liver-derived c-myc-overexpressing pre-B cell lines. We scored transformation by survival and/or expansion of differentiating B-lineage cells in vitro and in vivo. Only one double c-myc/cDNA-library-expressing cell line was found in less than 5 × 10(6) library-transduced pre-B cells surviving and expressing a cDNA-library-derived transcript in vitro. This transcript was identified as a shortened form of the Exosc1 gene, encoding the RNA exosome complex component CSL4. Transplantations of double c-myc/Exosc1 short-form- or c-myc/Exosc1 full-length-transgenic cells into Rag1(-/-) mice resulted in survival, differentiation to CD19(+) CD93(-) sIgM(+) CD5(low/-) CD11b(+) mature B1 cells and, surprisingly, also vigorous expansion in vivo. Strikingly, after transplantations of c-myc/cDNA-library pre-BI cells the frequencies of double-transgenic pre-B cells and their differentiated progeny, expanding in vivo to heterogeneous phenotypes, was at least tenfold higher than in vitro. In a first analysis Ptprcap, Cacybp, Ndufs7, Rpl18a, and Rpl35a were identified. This suggests a strong influence of the host on B-cell transformation. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. SIRT1 Limits Adipocyte Hyperplasia through c-Myc Inhibition.

    Science.gov (United States)

    Abdesselem, Houari; Madani, Aisha; Hani, Ahmad; Al-Noubi, Muna; Goswami, Neha; Ben Hamidane, Hisham; Billing, Anja M; Pasquier, Jennifer; Bonkowski, Michael S; Halabi, Najeeb; Dalloul, Rajaa; Sheriff, Mohamed Z; Mesaeli, Nasrin; ElRayess, Mohamed; Sinclair, David A; Graumann, Johannes; Mazloum, Nayef A

    2016-01-29

    The expansion of fat mass in the obese state is due to increased adipocyte hypertrophy and hyperplasia. The molecular mechanism that drives adipocyte hyperplasia remains unknown. The NAD(+)-dependent protein deacetylase sirtuin 1 (SIRT1), a key regulator of mammalian metabolism, maintains proper metabolic functions in many tissues, counteracting obesity. Here we report that differentiated adipocytes are hyperplastic when SIRT1 is knocked down stably in mouse 3T3-L1 preadipocytes. This phenotype is associated with dysregulated adipocyte metabolism and enhanced inflammation. We also demonstrate that SIRT1 is a key regulator of proliferation in preadipocytes. Quantitative proteomics reveal that the c-Myc pathway is altered to drive enhanced proliferation in SIRT1-silenced 3T3-L1 cells. Moreover, c-Myc is hyperacetylated, levels of p27 are reduced, and cyclin-dependent kinase 2 (CDK2) is activated upon SIRT1 reduction. Remarkably, differentiating SIRT1-silenced preadipocytes exhibit enhanced mitotic clonal expansion accompanied by reduced levels of p27 as well as elevated levels of CCAAT/enhancer-binding protein β (C/EBPβ) and c-Myc, which is also hyperacetylated. c-Myc activation and enhanced proliferation phenotype are also found to be SIRT1-dependent in proliferating mouse embryonic fibroblasts and differentiating human SW872 preadipocytes. Reducing both SIRT1 and c-Myc expression in 3T3-L1 cells simultaneously does not induce the adipocyte hyperplasia phenotype, confirming that SIRT1 controls adipocyte hyperplasia through c-Myc regulation. A better understanding of the molecular mechanisms of adipocyte hyperplasia will open new avenues toward understanding obesity.

  15. [Regulation of p14(ARF) expression and induction of cell apoptosis with c-myc in a p53-independent pathway].

    Science.gov (United States)

    Liu, Xiang-juan; Li, Fu-nian; Jiang, Dan-dan; Wang, Xin-gang; Liu, Xiang-ping; Zhang, Dian-liang; Meng, Chun-hui

    2012-08-14

    To explore the regulation of p14(ARF) expression and induction of cell apoptosis with the mutant and wild-type c-myc genes in a p53-independent pathway of signal transduction. The mutant and wild-type c-myc genes were transfected by lentivirus into HCC1937 to form the stable over-expression cell lines. Uninfected cells and lentivirus-infected ones carrying no c-myc gene acted as blank and infection controls respectively. And c-myc and p14(ARF) mRNA and protein, proliferation and apoptosis in HCC1937 with mutant and wild-type c-myc were detected by reverse transcription (RT)-PCR, Western blotting, thiazolyl blue tetrazolium bromide (MTT) and terminal deoxynucleotidyl transferase mediated X-dUTP nick end labeling (TUNEL) respectively. After the lentivirus-mediated gene transfer, c-myc mRNA and protein expression increased in the mutant and wild-type groups. p14(ARF) mRNA and protein increased in the wild-type group and the mutant group and there were significant difference between them with blank and infection controls (mutant groups: 0.560 ± 0.010, 0.154 ± 0.011, wild-type groups: 0.651 ± 0.010, 0.382 ± 0.013, both P c-myc could promote the proliferation of cell growth. And c-myc was more effective to induce apoptosis in the wild-type group as compared with the mutant group (7.1% ± 0.7% vs 3.2% ± 0.4%, P c-myc obviously up-regulates the expression of p14(ARF). And cell apoptosis may be induced through the regulation of p14(ARF)-related gene, keep balance of proliferative promotion and apoptosis induction. When there is a loss-of-function of mutant c-myc, tumorigenicity increases via a disturbed balance of proliferative promotion and apoptosis induction.

  16. Alteraciones del gen c-Myc en la oncogénesis = c-Myc gene alterations in oncogenesis

    Directory of Open Access Journals (Sweden)

    Ospina Pérez, Mariano

    2011-12-01

    Full Text Available La familia de protooncogenes MYC (c-Myc, N-Myc y L-Myc se relaciona con el origen de diversas neoplasias en seres humanos. Estos genes actúan como factores de transcripción y participan en la regulación del ciclo celular, la proliferación y diferenciación celulares, la apoptosis y la inmortalización. Los genes MYC se expresan en diferentes tejidos y responden a diversas señales internas y externas; codifican para la síntesis de factores de transcripción que se unen al ADN para regular la expresión de múltiples genes. El gen más ampliamente estudiado de esta familia es c-Myc, que se expresa en las células con mayor tasa de proli­feración. C-Myc se encuentra alterado en un gran número de tumores sólidos, leucemias y linfomas. Las alteraciones de c-Myc encontradas con mayor frecuencia en células cancero­sas son las amplificaciones, translocaciones, mutaciones y reordenamientos cromosómicos que involucran el locus de este gen y conducen a que se desregule su expresión en diversas neoplasias humanas. La amplificación de c-Myc es una alteración común en los cánceres de mama, pulmón, ovario y próstata, así como en leucemias y linfomas, mientras que la pérdida de su regulación es común en el cáncer de colon, en tumores ginecológicos y melanoma. En neoplasias con defectos de c-Myc los estudios actuales están dirigidos al desarrollo de nuevas estrategias terapéuticas.

  17. Normal Expression of a Rearranged and Mutated c-myc Oncogene after Transfection into Fibroblasts

    Science.gov (United States)

    Richman, Adam; Hayday, Adrian

    1989-10-01

    Expression of the c-myc oncogene is deregulated in a variety of malignancies. Rearrangement and mutation of the c-myc locus is a characteristic feature of human Burkitt's lymphoma. Whether deregulation is solely a result of mutation of c-myc or whether it is influenced by the transformed B cell context has not been determined. A translocated and mutated allele of c-myc was stably transfected into fibroblasts. The rearranged allele was expressed indistinguishably from a normal c-myc gene: it had serum-regulated expression, was transcribed with normal promoter preference, and was strongly attenuated. Thus mutations by themselves are insufficient to deregulate c-myc transcription.

  18. Functional analysis of Burkitt's lymphoma mutant c-Myc proteins

    NARCIS (Netherlands)

    Smith-Sørensen, B.; Hijmans, E.M.; Bernards, R.A.

    1996-01-01

    The c-myc gene encodes a sequence-specific DNA binding protein that activates transcription of cellular genes. Transcription activation by Myc proteins is regulated by phosphorylation of serine and threonine residues within the transactivation domain and by complex formation with the retinoblastoma-

  19. Prostaglandin E2 promotes the cell growth and invasive ability of hepatocellular carcinoma cells by upregulating c-Myc expression via EP4 receptor and the PKA signaling pathway.

    Science.gov (United States)

    Xia, Shukai; Ma, Juan; Bai, Xiaoming; Zhang, Hai; Cheng, Shanyu; Zhang, Min; Zhang, Li; Du, Mingzhan; Wang, Yipin; Li, Hai; Rong, Rong; Shi, Feng; Yang, Qinyi; Leng, Jing

    2014-10-01

    Hepatocellular carcinoma (HCC) represents a major health problem worldwide. Prostaglandin E2 (PGE2), the predominant product of cyclooxygenase-2, has been implicated in hepatocarcinogenesis. However, the underlying molecular mechanisms remain to be further elucidated. c-myc, a cellular proto-oncogene, is activated or overexpressed in many types of human cancer, including HCC. The present study was designed to investigate the internal relationship and molecular mechanisms between PGE2 and c-Myc in HCC, and to define its role in HCC cell growth and invasion. Our results showed that PGE2 significantly upregulated c-Myc expression at both the mRNA and protein levels, and knockdown of c-Myc blocked PGE2-induced HCC cell growth and invasive ability in human HCC Huh-7 cells. The effect of PGE2 on c-Myc expression was mainly through the EP4 receptor, and EP4 receptor-mediated c-Myc protein upregulation largely depended on de novo biosynthesis of c-Myc mRNA and its protein. EP4 receptor signaling activated GS/AC and increased the intracellular cAMP level in Huh-7 cells. The adenylate cyclase (AC) activator forskolin mimicked the effects of the EP4 receptor agonist on c-Myc expression, while the AC inhibitor SQ22536 reduced EP4 receptor-mediated c-Myc upregulation. These data confirm the involvement of the GS/AC/cAMP pathway in EP4 receptor-mediated c-Myc upregulation. Moreover, the phosphorylation levels of CREB protein were markedly elevated by EP4 receptor signaling, and by using specific inhibitor and siRNA interference, we demonstrated that PKA/CREB was also involved in the EP4 receptor-mediated c-Myc upregulation. In summary, the present study revealed that PGE2 significantly upregulates c-Myc expression at both mRNA and protein levels through the EP4R/GS/AC/cAMP/PKA/CREB signaling pathway, thus promoting cell growth and invasion in HCC cells. Targeting of the PGE2/EP4R/c-Myc pathway may be a new therapeutic strategy to prevent and cure human HCC.

  20. Postnatal liver growth and regeneration are independent of c-myc in a mouse model of conditional hepatic c-myc deletion

    Directory of Open Access Journals (Sweden)

    Sanders Jennifer A

    2012-03-01

    Full Text Available Abstract Background The transcription factor c-myc regulates genes involved in hepatocyte growth, proliferation, metabolism, and differentiation. It has also been assigned roles in liver development and regeneration. In previous studies, we made the unexpected observation that c-Myc protein levels were similar in proliferating fetal liver and quiescent adult liver with c-Myc displaying nucleolar localization in the latter. In order to investigate the functional role of c-Myc in adult liver, we have developed a hepatocyte-specific c-myc knockout mouse, c-mycfl/fl;Alb-Cre. Results Liver weight to body weight ratios were similar in control and c-myc deficient mice. Liver architecture was unaffected. Conditional c-myc deletion did not result in compensatory induction of other myc family members or in c-Myc's binding partner Max. Floxed c-myc did have a negative effect on Alb-Cre expression at 4 weeks of age. To explore this relationship further, we used the Rosa26 reporter line to assay Cre activity in the c-myc floxed mice. No significant difference in Alb-Cre activity was found between control and c-mycfl/fl mice. c-myc deficient mice were studied in a nonproliferative model of liver growth, fasting for 48 hr followed by a 24 hr refeeding period. Fasting resulted in a decrease in liver mass and liver protein, both of which recovered upon 24 h of refeeding in the c-mycfl/fl;Alb-Cre animals. There was also no effect of reducing c-myc on recovery of liver mass following 2/3 partial hepatectomy. Conclusions c-Myc appears to be dispensable for normal liver growth during the postnatal period, restoration of liver mass following partial hepatectomy and recovery from fasting.

  1. Expression of telomerase hTERT in human non-small cell lung cancer and its correlation with c-myc gene

    Institute of Scientific and Technical Information of China (English)

    耿志华; 张敦华; 刘银坤

    2003-01-01

    Objective To investigate the expression of human telomerase catalytic subunit, hTERT, in human non-small cell lung cancer (NSCLC) and its correlations to c-myc gene.Methods hTERT and c-myc mRNA expressions were detected by semiquantitative reverse transcription-polymerase chain reaction (RT-PCR). Statistical correlation analysis was made to estimate whether there was interrelation between them.Results Positive rate of hTERT expression in 51 surgically resected lung cancer specimens was 86.3%, significantly higher than that in adjacent non-neoplastic lung tissues and benign lesions, which were 14.3% and 27.3% respectively. No statistical significance was observed between the frequency of hTERT expression and histologic types, degree of differentiation, TNM stages, tumor size or lymph nodes metastases. Correlation analysis revealed that the expression of c-myc gene was significantly related to that of hTERT (correlation coefficient, r=0.633, P<0.001).Conclusions hTERT may be a useful tumor marker in diagnosing lung cancer. Significant correlation between the expression of hTERT and c-myc mRNA indicates that the activation and up-regulation of hTERT might be conferred by over-expression of c-myc gene.

  2. Tissue array for Tp53, C-myc, CCND1 gene over-expression in different tumors

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    AIM: To rapidly detect molecular alterations in different malignancies and investigate the possible role of Tp53, C-myc, and CCND1 genes in development of tumors in human organs and their adjacent normal tissues, as well as the possible relation between well- and poorly-differentiated tumors. METHODS: A tissue array consisting of seven different tumors was generated. The tissue array included 120 points of esophagus, 120 points of stomach, 80 points of rectum, 60 points of thyroid gland, 100 points of mammary gland, 80 points ofliver, and 80 points of colon. Expressions of Tp53, C-myc, and CCND1 were determined by RNA in situ hybridization. 3' terminal digoxin-labeled anti-sense single stranded oligonucleotide and locked nucleic acid modifying probe were used.RESULTS: The expression level of Tp53 gene was higher in six different carcinoma tissue samples than in paracancerous tissue samples with the exception in colon carcinoma tissue samples (P < 0.05). The expression level of CCND1 gene was significantly different in different carcinoma tissue samples with the exception in esophagus and colon carcinoma tissue samples. The expression level of C-myc gene was different in esophagus carcinoma tissue samples (x2 = 18.495, P = 0.000), stomach carcinoma tissue samples (x2 = 23.750, P = 0.000), and thyroid gland tissue samples (x2 = 10.999, P = 0.004). The intensity of signals was also different in different carcinoma tissue samples and paracancerous tissue samples.CONCLUSION: Over-expression of the Tp53, CCND1, and C-myc genes appears to play a role in development of human cancer by regulating the expression of mRNA. Tp53, CCND1 and C-myc genes are significantly correlated with the development of different carcinomas.

  3. Inhibition of c-Myc by let-7b mimic reverses mutidrug resistance in gastric cancer cells.

    Science.gov (United States)

    Yang, Xiaojun; Cai, Hui; Liang, Yuhe; Chen, Lin; Wang, Xiangdong; Si, Ruohuang; Qu, Kunpeng; Jiang, Zebin; Ma, Bingqiang; Miao, Changfeng; Li, Jing; Wang, Bin; Gao, Peng

    2015-04-01

    Chemotherapy is one of the few effective choices for patients with advanced or recurrent gastric cancer (GC). However, the development of mutidrug resistance (MDR) to cancer chemotherapy is a major obstacle to the effective treatment of advanced GC. Additionally, the mechanism of MDR remains to be determined. In the present study, we tested IC50 of cisplatin (DDP), vincristine (VCR) and 5-fluorouracil (5-FU) in SGC7901, SGC7901/DDP and SGC7901/VCR gastric cancer cells using an MTT assay. The expression of let-7b and c-Myc in these cells was detected by qPCR and western blot analysis. The relationship between let-7b and c-Myc was explored using a luciferase reporter assay. Transfection of let-7b mimic or inhibitor was used to confirm the effect of let-7b on drug sensitivity in chemotherapy via the regulation of c-Myc expression. We found that the expression of let-7b was lower in chemotherapy-resistant SGC7901/DDP and SGC7901/VCR gastric cancer cells than that in chemotherapy-sensitive SGC7901 cells. By contrast, the expression of c-Myc was higher in SGC7901/DDP and SGC7901/VCR cells than that in SGC7901 cells. Furthermore, we confirmed that let-7b suppresses c-Myc gene expression at the mRNA and protein levels in a sequence-specific manner, while transfection of let-7b mimic increases drug sensitivity in chemotherapy-resistant SGC7901/DDP and SGC7901/VCR cells by targeting downregulation of c-Myc. In SGC7901 drug-sensitive cells, however, the sensitivity of chemotherapy was significantly decreased following let-7b inhibitor transfection. The present study results demonstrated that let-7b increases drug sensitivity in chemotherapy‑resistant SGC7901/DDP and SGC7901/VCR gastric cancer cells by targeting the downregulation of c-Myc and that, let-7b mimic reverses MDR by promoting cancer stem cell differentiation controlled by double-negative autoregulatory loops (Lin28/let-7 and Myc/let-7) and a double-positive autoregulatory loop (Lin28/Lin28B/Myc) existing in GC

  4. Ezrin mediates c-Myc actions in prostate cancer cell invasion

    DEFF Research Database (Denmark)

    Chuan, Yin Choy; Iglesias Gato, Diego; Fernandez-Perez, L

    2010-01-01

    The forced overexpression of c-Myc in mouse prostate and in normal human prostate epithelial cells results in tumor transformation with an invasive phenotype. How c-Myc regulates cell invasion is poorly understood. In this study, we have investigated the interplay of c-Myc and androgens in the re...

  5. Depletion of NEAT1 lncRNA attenuates nucleolar stress by releasing sequestered P54nrb and PSF to facilitate c-Myc translation.

    Science.gov (United States)

    Shen, Wen; Liang, Xue-Hai; Sun, Hong; De Hoyos, Cheryl L; Crooke, Stanley T

    2017-01-01

    Altered expression of NEAT1, the architectural long non-coding RNA (lncRNA) of nuclear paraspeckles, has been reported during tumorigenesis, as well as under various cellular stress conditions. Here we report that the depletion of NEAT1 lncRNA alleviates nucleolar stress during RNAP I inhibition through releasing sequestered P54nrb and PSF to facilitate the IRES-dependent translation of c-Myc. RNAP I inhibitor CX5461 disrupts the SL1-rDNA interaction and induces nucleolar disruption, demonstrated by the accumulation of fibrillarin-containing nucleoplasmic foci and nucleolar clearance of ribosomal proteins in HeLa cells. Antisense oligonucleotide-mediated depletion of NEAT1 lncRNA significantly attenuated the RNAP I inhibition and its related nucleolar disruption. Interestingly, induction in the levels of c-Myc protein was observed in NEAT1-depeleted cells under RNAP I inhibition. NEAT1-associated paraspeckle proteins P54nrb and PSF have been reported as positive regulators of c-Myc translation through interaction with c-Myc IRES. Indeed, an increased association of P54nrb and PSF with c-Myc mRNA was observed in NEAT1-depleted cells. Moreover, apoptosis was observed in HeLa cells depleted of P54nrb and PSF, further confirming the positive involvement of P54nrb and PSF in cell proliferation. Together, our results suggest that NEAT1 depletion rescues CX5461-induced nucleolar stress through facilitating c-Myc translation by relocating P54nrb/PSF from nuclear paraspeckles to c-Myc mRNAs.

  6. Constitutive gray hair in mice induced by melanocyte-specific deletion of c-Myc

    Science.gov (United States)

    Pshenichnaya, Irina; Schouwey, Karine; Armaro, Marzia; Larue, Lionel; Knoepfler, Paul S.; Eisenman, Robert N.; Trumpp, Andreas; Delmas, Véronique; Beermann, Friedrich

    2012-01-01

    Summary c-Myc is involved in the control of diverse cellular processes and implicated in the maintenance of different tissues including the neural crest. Here, we report that c-Myc is particularly important for pigment cell development and homeostasis. Targeting c-Myc specifically in the melanocyte lineage using the floxed allele of c-Myc and Tyr::Cre transgenic mice results in a congenital gray hair phenotype. The gray coat color is associated with a reduced number of functional melanocytes in the hair bulb and melanocyte stem cells in the hair bulge. Importantly, the gray phenotype does not progress with time, suggesting that maintenance of the melanocyte through the hair cycle does not involve c-Myc function. In embryos, at E13.5, c-Myc-deficient melanocyte precursors are affected in proliferation in concordance with a reduction in numbers, showing that c-Myc is required for the proper melanocyte development. Interestingly, melanocytes from c-Myc-deficient mice display elevated levels of the c-Myc paralog N-Myc. Double deletion of c-Myc and N-Myc results in nearly complete loss of the residual pigmentation, indicating that N-Myc is capable of compensating for c-Myc loss of function in melanocytes. PMID:22420299

  7. BPTF is required for c-MYC transcriptional activity and in vivo tumorigenesis

    Science.gov (United States)

    Richart, Laia; Carrillo-de Santa Pau, Enrique; Río-Machín, Ana; de Andrés, Mónica P.; Cigudosa, Juan C.; Lobo, Víctor J. Sánchez-Arévalo; Real, Francisco X.

    2016-01-01

    c-MYC oncogene is deregulated in most human tumours. Histone marks associated with transcriptionally active genes define high-affinity c-MYC targets. The mechanisms involved in their recognition by c-MYC are unknown. Here we report that c-MYC interacts with BPTF, a core subunit of the NURF chromatin-remodelling complex. BPTF is required for the activation of the full c-MYC transcriptional programme in fibroblasts. BPTF knockdown leads to decreased c-MYC recruitment to DNA and changes in chromatin accessibility. In Bptf-null MEFs, BPTF is necessary for c-MYC-driven proliferation, G1–S progression and replication stress, but not for c-MYC-driven apoptosis. Bioinformatics analyses unveil that BPTF levels correlate positively with c-MYC-driven transcriptional signatures. In vivo, Bptf inactivation in pre-neoplastic pancreatic acinar cells significantly delays tumour development and extends survival. Our findings uncover BPTF as a crucial c-MYC co-factor required for its biological activity and suggest that the BPTF-c-MYC axis is a potential therapeutic target in cancer. PMID:26729287

  8. Effects of alcohol on c-Myc protein in the brain.

    Science.gov (United States)

    Akinyeke, Tunde; Weber, Sydney J; Davenport, April T; Baker, Erich J; Daunais, James B; Raber, Jacob

    2017-03-01

    Alcoholism is a disorder categorized by significant impairment that is directly related to persistent and extreme use of alcohol. The effects of alcoholism on c-Myc protein expression in the brain have been scarcely studied. This is the first study to investigate the role different characteristics of alcoholism have on c-Myc protein in the brain. We analyzed c-Myc protein in the hypothalamus and amygdala from five different animal models of alcohol abuse. c-Myc protein was increased following acute ethanol exposure in a mouse knockout model and following chronic ethanol consumption in vervet monkeys. We also observed increases in c-Myc protein exposure in animals that are genetically predisposed to alcohol and methamphetamine abuse. Lastly, c-Myc protein was increased in animals that were acutely exposed to methamphetamine when compared to control treated animals. These results suggest that in substance abuse c-Myc plays an important role in the brain's response.

  9. Kinetic profiling of the c-Myc transcriptome and bioinformatic analysis of repressed gene promoters

    Science.gov (United States)

    Yap, Chui-Sun; Peterson, Abigail L; Castellani, Gastone

    2011-01-01

    Mammalian c-Myc is a member of a small family of three related proto-oncogenic transcription factors. c-Myc has an unusually broad array of regulatory functions, which include roles in cell cycle and apoptosis, a variety of metabolic functions, cell differentiation, senescence and stem cell maintenance. c-Myc modulates the expression of a very large number of genes, but the magnitude of the majority of the regulatory effects is only two-fold or less. c-Myc can both activate and repress the promoters of its target genes. Identification of genes directly regulated by c-Myc has been an enduring question in the field. We report here microarray expression profiling of a high resolution time course of c-Myc induction, using fibroblast cells in which c-Myc activity can be modulated from null to physiological. The c-Myc transcriptome data set presented is the largest reported to date with 4,186 differentially regulated genes (1,826 upregulated, 2,360 downregulated, 1% FDR). The gene expression patterns fit well with the known biological functions of c-Myc. We describe several novel findings and present tools for further data mining. Although the mechanisms of transcriptional activation by c-Myc are well understood, how c-Myc represses an even greater number of genes remains incompletely described. One mechanism involves the binding of c-Myc to other, positively acting transcription factors and interfering with their activities. We identified rapid-response genes likely to be direct c-Myc targets and analyzed the promoters of the repressed genes to identify transcription factors that could be targets of c-Myc repression. PMID:21623162

  10. Molecular characterizations of Nop16 in murine mammary tumors with varying levels of c-Myc.

    Science.gov (United States)

    Kundel, Donald W; Stromquist, Emily; Greene, Amy L; Zhdankin, Olga; Regal, Ronald R; Rose-Hellekant, Teresa A

    2012-04-01

    NOP16, also known as HSPC111, has been identified as a MYC and estrogen regulated gene in in vitro studies, hence coexpression levels were strongly correlated. Importantly, high expression of NOP16 was associated with poor clinical outcome in breast cancer patients. However, coexpression of NOP16, MYC and estrogen receptor (ESR1) varied widely in tumors and cell lines suggesting that transcriptional regulation differed according to pathological environments. The goal of this study was to determine the expression patterns of Nop16, Myc and Esr1 in murine mammary tumors with disparate histopathological and molecular features. We hypothesized that tumor environments with relatively high Myc levels would have different coexpression patterns than tumor environments with relatively low Myc levels. We measured levels of Myc and Nop16 mRNA and protein in tumors from WAP-c-myc mice that were of high grade and metastasized frequently. In contrast, Myc and Nop16 mRNA and proteins levels were significantly lower in the less aggressive tumors that developed in NRL-TGFα mice. Tumors from both mouse lines express ESR1 protein and we found that Esr1 mRNA levels correlated positively with Myc levels in both models. However, Myc and Nop16 transcript levels correlated positively only in tumors from NRL-TGFα mice. We identified prominent NOP16 protein in nuclei and less prominent staining in the cytoplasm of luminal cells of ducts and lobules from normal mammary glands as well as in hyperplasias and tumors obtained from NRL-TGFα mice. This staining pattern was reversed in tumors from WAP-c-Myc mice as nuclear staining was faint or absent and cytoplasmic staining more pronounced. In summary, the regulation of expression and localization of NOP16 varies in tumor environments with high versus low MYC levels and demonstrate the importance of stratifying clinical breast cancers based on MYC levels.

  11. c-myc and skp2 coordinate p27 degradation, vascular smooth muscle proliferation, and neointima formation induced by the parathyroid hormone-related protein.

    Science.gov (United States)

    Sicari, Brian M; Troxell, Ronnie; Salim, Fatimah; Tanwir, Mansoor; Takane, Karen K; Fiaschi-Taesch, Nathalie

    2012-02-01

    Parathyroid hormone-related protein (PTHrP) contains a classical bipartite nuclear localization signal. Nuclear PTHrP induces proliferation of arterial vascular smooth muscle cells (VSMC). In the arterial wall, PTHrP is markedly up-regulated in response to angioplasty and promotes arterial restenosis. PTHrP overexpression exacerbates arterial restenosis, and knockout of the PTHrP gene results in decreased VSMC proliferation in vivo. In arterial VSMC, expression of the cell cycle inhibitor, p27, rapidly decreases after angioplasty, and replacement of p27 markedly reduces neointima development. We have shown that PTHrP overexpression in VSMC leads to p27 down-regulation, mostly through increased proteosomal degradation. Here, we determined the molecular mechanisms through which PTHrP targets p27 for degradation. S-phase kinase-associated protein 2 (skp2) and c-myc, two critical regulators of p27 expression and stability, and neointima formation were up-regulated in PTHrP overexpression in VSMC. Normalization of skp2 or c-myc using small interfering RNA restores normal cell cycle and p27 expression in PTHrP overexpression in VSMC. These data indicate that skp2 and c-myc mediate p27 loss and proliferation induced by PTHrP. c-myc promoter activity was increased, and c-myc target genes involved in p27 stability were up-regulated in PTHrP overexpression in VSMC. In primary VSMC, PTHrP overexpression led to increased c-myc and decreased p27. Conversely, knockdown of PTHrP in primary VSMC from PTHrP(flox/flox) mice led to cell cycle arrest, p27 up-regulation, with c-myc and skp2 down-regulation. Collectively, these data describe for the first time the role of PTHrP in the regulation of skp2 and c-myc in VSMC. This novel PTHrP-c-myc-skp2 pathway is a potential target for therapeutic manipulation of the arterial response to injury.

  12. The Role of c-MYC in B-Cell Lymphomas: Diagnostic and Molecular Aspects.

    Science.gov (United States)

    Nguyen, Lynh; Papenhausen, Peter; Shao, Haipeng

    2017-04-05

    c-MYC is one of the most essential transcriptional factors, regulating a diverse array of cellular functions, including proliferation, growth, and apoptosis. Dysregulation of c-MYC is essential in the pathogenesis of a number of B-cell lymphomas, but is rarely reported in T-cell lymphomas. c-MYC dysregulation induces lymphomagenesis by loss of the tight control of c-MYC expression, leading to overexpression of intact c-MYC protein, in contrast to the somatic mutations or fusion proteins seen in many other oncogenes. Dysregulation of c-MYC in B-cell lymphomas occurs either as a primary event in Burkitt lymphoma, or secondarily in aggressive lymphomas such as diffuse large B-cell lymphoma, plasmablastic lymphoma, mantle cell lymphoma, or double-hit lymphoma. Secondary c-MYC changes include gene translocation and gene amplification, occurring against a background of complex karyotype, and most often confer aggressive clinical behavior, as evidenced in the double-hit lymphomas. In low-grade B-cell lymphomas, acquisition of c-MYC rearrangement usually results in transformation into highly aggressive lymphomas, with some exceptions. In this review, we discuss the role that c-MYC plays in the pathogenesis of B-cell lymphomas, the molecular alterations that lead to c-MYC dysregulation, and their effect on prognosis and diagnosis in specific types of B-cell lymphoma.

  13. Celastrol inhibits chondrosarcoma proliferation, migration and invasion through suppression CIP2A/c-MYC signaling pathway

    Directory of Open Access Journals (Sweden)

    Jinhui Wu

    2017-05-01

    Full Text Available Chondrosarcomas (CS is the second most frequent tumors of cartilage origin. A small compound extracted from Thunder God Vine (Tripterygium wilfordii Hook. F. called celastrol can directly bound CIP2A protein and effectively inhibit cell proliferation and induce apoptosis in several cancer cells. However, little knowledge is concern about the important role of CIP2A in CS patients and the therapeutic value of celastrol on CS. Our results showed that CIP2A and c-MYC were verified to be oncoproteins by detecting their mRNA and protein expression in 10 human CS tissues by qRT-PCR and Western blots. After treatment of celastrol, the proliferation, migration and invasion were significantly inhibited; whereas the apoptosis was largely induced in human CS cell lines. In addition, celastrol inhibited the expression of CIP2A, c-MYC, and suppressed apoptotic proteins BAX and caspase-8 in human CS cells, on the other hand, it induced the expression of antiapoptotic protein Bcl-2. Finally, knockdown of CIP2A also inhibited the migration and invasion and induced apoptosis of human CS cells. To sum up, we found that celastrol had effects on inhibiting proliferation, migration, invasion and inducing apoptosis through suppression CIP2A/c-MYC signaling pathway in vitro, which may provide a new therapeutic regimen for CS.

  14. miR-320b suppresses cell proliferation by targeting c-Myc in human colorectal cancer cells.

    Science.gov (United States)

    Wang, Hantao; Cao, Fuao; Li, Xu; Miao, Hua; E, Jifu; Xing, Junjie; Fu, Chuan-Gang

    2015-10-20

    MicroRNAs (miRNAs) are small noncoding RNAs that potentially play a critical role in tumorigenesis. Mounting evidence indicates that one specific miRNA: miR-320b is down regulated in numerous human cancers, including colorectal cancer (CRC); making the hypothesis that miR-320b may play a key role in tumorigenesis plausible. However, its role in carcinogenesis remains poorly defined. The goal of this study is to better clarify the role of miR-320b in tumor growth of CRC. Quantitative reverse-transcription polymerase chain reaction (qRT-PCR) was conducted to detect the expression of miR-320b in CRC tissues and 5 CRC cell lines. The effect of miR-320b on cell proliferation was analyzed in vitro and in vivo. Furthermore, a luciferase reporter assay was performed to measure the target effects of miR-320b. Lastly, the messenger RNA (mRNA) and protein levels of the gene c-MYC were measured in CRC cell lines and tissues by qRT-PCR, and confirmed via Western blot and Immunohistochemical (IHC) staining. The results presented here showed that miR-320b expression was down regulated in both CRC tissues and cells. Overexpression of miR-320b in CRC cells was statistically correlated with a decrease of cell growth in vitro and in vivo, while c-MYC was identified as a target gene of miR-320b in CRC. Furthermore, it was found that up-regulation of c-Myc can attenuate the effects induced by miR-320b. Our identification of c-MYC as a target gene of miR-320b provides new insights into the pathophysiology of CRC proliferation, and identifies miR-320b as a novel therapeutic target for the treatment of CRC.

  15. 通脉汤方对实验性动脉粥样硬化家兔胸主动脉表皮生长因子受体和c-myc基因表达的影响%Effect of Tongmai Recipe on Epidermal Growth Factor Receptor and Protooncogene c-myc mRNA Expression in Aorta of Atherosclerotic Rabbit

    Institute of Scientific and Technical Information of China (English)

    张娟; 孙明; 周宏研

    2007-01-01

    目的 探讨通脉方对实验性动脉粥样硬化家兔胸主动脉表皮生长因子受体和c-myc基因表达的影响.方法 日本大耳白兔40只,随机分为4组:①对照组10只,以普通饲料喂养,每日两次;②模型组10只,以高胆固醇饲料[胆固醇0.5 g/(kg·d)、蛋黄2 g/(kg·d)和猪油2 g/(kg·d)]喂养,每日两次;③通脉汤方低剂量组(简称低剂量组)10只,高胆固醇饲料喂养(剂量同模型组),同时予通脉汤方灌胃,每只剂量相当于生药7.3 g/(kg*d),分上下午两次给药;④通脉汤方高剂量组(简称高剂量组)10只,高胆固醇饲料喂养(剂量同模型组),同时予通脉汤方灌胃,每只剂量相当于生药21.9 g/(kg·d),分上下午两次给药;共喂养16周.运用免疫组织化学染色法检测主动脉表皮生长因子受体的表达,同时用内参比逆转录聚合酶链反应定量分析c-myc mRNA在主动脉的表达.结果 模型组主动脉表皮生长因子受体及c-myc mRNA表达显著高于对照组(分别为0.327±0.030比0.209±0.006,P0.05;0.44±0.09比0.52±0.11 P>0.05).结论 ①动脉粥样硬化时促进血管平滑肌细胞增殖的表皮生长因子受体及原癌基因c-myc mRNA表达增强.②通脉汤方通过抑制血管壁表皮生长因子受体及c-myc基因的表达,从而抑制血管平滑肌细胞增殖.

  16. Involvement of SIRT1 in hypoxic down-regulation of c-Myc and β-catenin and hypoxic preconditioning effect of polyphenols

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Kyung-Soo [Department of Biochemistry, Pusan National University School of Medicine, Yangsan (Korea, Republic of); Research Center for Ischemic Tissue regeneration, Pusan National University School of Medicine, Yangsan (Korea, Republic of); Park, Jun-Ik [Department of Biochemistry, Pusan National University School of Medicine, Yangsan (Korea, Republic of); Kim, Mi-Ju; Kim, Hak-Bong; Lee, Jae-Won [Department of Biochemistry, Pusan National University School of Medicine, Yangsan (Korea, Republic of); Research Center for Ischemic Tissue regeneration, Pusan National University School of Medicine, Yangsan (Korea, Republic of); Dao, Trong Tuan; Oh, Won Keun [BK21 Project Team, College of Pharmacy, Chosun University, Gwangju (Korea, Republic of); Kang, Chi-Dug, E-mail: kcdshbw@pusan.ac.kr [Department of Biochemistry, Pusan National University School of Medicine, Yangsan (Korea, Republic of); Kim, Sun-Hee, E-mail: ksh7738@pusan.ac.kr [Department of Biochemistry, Pusan National University School of Medicine, Yangsan (Korea, Republic of); Research Center for Ischemic Tissue regeneration, Pusan National University School of Medicine, Yangsan (Korea, Republic of)

    2012-03-01

    SIRT1 has been found to function as a Class III deacetylase that affects the acetylation status of histones and other important cellular nonhistone proteins involved in various cellular pathways including stress responses and apoptosis. In this study, we investigated the role of SIRT1 signaling in the hypoxic down-regulations of c-Myc and β-catenin and hypoxic preconditioning effect of the red wine polyphenols such as piceatannol, myricetin, quercetin and resveratrol. We found that the expression of SIRT1 was significantly increased in hypoxia-exposed or hypoxic preconditioned HepG2 cells, which was closely associated with the up-regulation of HIF-1α and down-regulation of c-Myc and β-catenin expression via deacetylation of these proteins. In addition, blockade of SIRT1 activation using siRNA or amurensin G, a new potent SIRT1 inhibitor, abolished hypoxia-induced HIF-1α expression but increased c-Myc and β-catenin expression. SIRT1 was also found to stabilize HIF-1α protein and destabilize c-Myc, β-catenin and PHD2 under hypoxia. We also found that myricetin, quercetin, piceatannol and resveratrol up-regulated HIF-1α and down-regulated c-Myc, PHD2 and β-catenin expressions via SIRT1 activation, in a manner that mimics hypoxic preconditioning. This study provides new insights of the molecular mechanisms of hypoxic preconditioning and suggests that polyphenolic SIRT1 activators could be used to mimic hypoxic/ischemic preconditioning. -- Graphical abstract: Polyphenols mimicked hypoxic preconditioning by up-regulating HIF-1α and SIRT1 and down-regulating c-Myc, PHD2, and β-catenin. HepG2 cells were pretreated with the indicated doses of myricetin (MYR; A), quercetin (QUR; B), or piceatannol (PIC; C) for 4 h and then exposed to hypoxia for 4 h. Levels of HIF-1α, SIRT1, c-Myc, β-catenin, and PHD2 were determined by western blot analysis. The data are representative of three individual experiments. Highlights: ► SIRT1 expression is increased in hypoxia

  17. miR-26a and miR-26b inhibit esophageal squamous cancer cell proliferation through suppression of c-MYC pathway.

    Science.gov (United States)

    Li, Juan; Liang, Yue; Lv, Hao; Meng, Hui; Xiong, Gang; Guan, Xingying; Chen, Xuedan; Bai, Yun; Wang, Kai

    2017-08-20

    Dysregulation of c-Myc is one of the most common abnormalities in human malignancies, including esophageal cancer, one of the world's most lethal cancers. MicroRNA-26 family, including miR-26a and miR-26b, is transcriptionally suppressed by c-MYC. Our previous microarray data indicated a decreased-expression of miR-26 family in esophageal squamous cell carcinoma (ESCC). However, its roles in c-MYC pathway regulation and esophageal cancer tumorigenesis have yet not been elucidated. In this study, we expanded the detection of miR-26 expression in ESCC patients and found that the great majority of ESCC tissues showed an >50% reduction, even in the early-staged tumor. Furthermore, ectopic expression of miR-26a or miR-26b induced ESCC cell growth inhibition and G1 phase arrest. MYC binding protein (MYCBP) was identified as a direct target of miR-26. MiR-26 could dramatically decrease MYCBP mRNA and protein levels, as well as the expression of luciferase carrying MYCBP 3'-untranslated region. Moreover, knock-down of MYCBP mimicked the effect of miR-26. More importantly, miR-26 overexpression could downregulate a series of c-MYC target genes as MYCBP silence did. Taken together, these results indicate that miR-26 family can suppress esophageal cancer cell proliferation by inhibition of MYCBP, subsequently downregulate c-MYC pathway. Besides, we also found that reduction of miR-26 expression in ESCC was not due to DNA methylation. Hence, our study reveals a novel feedback loop for c-MYC pathway and implicates miR-26 as a potential target for prevention and treatment of esophageal cancer. Copyright © 2017 Elsevier B.V. All rights reserved.

  18. Rictor regulates FBXW7-dependent c-Myc and cyclin E degradation in colorectal cancer cells

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Zheng [Markey Cancer Center, The University of Kentucky, 800 Rose Street, Lexington, KY 40536 (United States); Guangdong Provincial Key Laboratory of Gastroenterology, Department of Gastroenterology, Nanfang Hospital, Southern Medical University, 1838 Guangzhou Dadao Bei, Guangzhou 510515 (China); Zhou, Yuning [Markey Cancer Center, The University of Kentucky, 800 Rose Street, Lexington, KY 40536 (United States); Evers, B. Mark [Markey Cancer Center, The University of Kentucky, 800 Rose Street, Lexington, KY 40536 (United States); Department of Surgery, The University of Kentucky, 800 Rose Street, Lexington, KY 40536 (United States); Wang, Qingding, E-mail: qingding.wang@uky.edu [Markey Cancer Center, The University of Kentucky, 800 Rose Street, Lexington, KY 40536 (United States); Department of Surgery, The University of Kentucky, 800 Rose Street, Lexington, KY 40536 (United States)

    2012-02-10

    Highlights: Black-Right-Pointing-Pointer Rictor associates with FBXW7 to form an E3 complex. Black-Right-Pointing-Pointer Knockdown of rictor decreases ubiquitination of c-Myc and cylin E. Black-Right-Pointing-Pointer Knockdown of rictor increases protein levels of c-Myc and cylin E. Black-Right-Pointing-Pointer Overexpression of rictor induces the degradation of c-Myc and cyclin E proteins. Black-Right-Pointing-Pointer Rictor regulation of c-Myc and cyclin E requires FBXW7. -- Abstract: Rictor (Rapamycin-insensitive companion of mTOR) forms a complex with mTOR and phosphorylates and activates Akt. Activation of Akt induces expression of c-Myc and cyclin E, which are overexpressed in colorectal cancer and play an important role in colorectal cancer cell proliferation. Here, we show that rictor associates with FBXW7 to form an E3 complex participating in the regulation of c-Myc and cyclin E degradation. The Rictor-FBXW7 complex is biochemically distinct from the previously reported mTORC2 and can be immunoprecipitated independently of mTORC2. Moreover, knocking down of rictor in serum-deprived colorectal cancer cells results in the decreased ubiquitination and increased protein levels of c-Myc and cyclin E while overexpression of rictor induces the degradation of c-Myc and cyclin E proteins. Genetic knockout of FBXW7 blunts the effects of rictor, suggesting that rictor regulation of c-Myc and cyclin E requires FBXW7. Our findings identify rictor as an important component of FBXW7 E3 ligase complex participating in the regulation of c-Myc and cyclin E protein ubiquitination and degradation. Importantly, our results suggest that elevated growth factor signaling may contribute to decrease rictor/FBXW7-mediated ubiquitination of c-Myc and cyclin E, thus leading to accumulation of cyclin E and c-Myc in colorectal cancer cells.

  19. c-Myc Suppression of DNA Double-strand Break Repair12

    Science.gov (United States)

    Li, Zhaozhong; Owonikoko, Taofeek K; Sun, Shi-Yong; Ramalingam, Suresh S; Doetsch, Paul W; Xiao, Zhi-Qiang; Khuri, Fadlo R; Curran, Walter J; Deng, Xingming

    2012-01-01

    c-Myc is a transcriptional factor that functions as a central regulator of cell growth, proliferation, and apoptosis. Overexpression of c-Myc also enhances DNA double-strand breaks (DSBs), genetic instability, and tumorigenesis. However, the mechanism(s) involved remains elusive. Here, we discovered that γ-ray ionizing radiation-induced DSBs promote c-Myc to form foci and to co-localize with γ-H2AX. Conditional expression of c-Myc in HO15.19 c-Myc null cells using the Tet-Off/Tet-On inducible system results in down-regulation of Ku DNA binding and suppressed activities of DNA-dependent protein kinase catalytic subunit (DNA-PKcs) and DNA end-joining, leading to inhibition of DSB repair and enhanced chromosomal and chromatid breaks. Expression of c-Myc reduces both signal and coding joins with decreased fidelity during V(D)J recombination. Mechanistically, c-Myc directly interacts with Ku70 protein through its Myc box II (MBII) domain. Removal of the MBII domain from c-Myc abrogates its inhibitory effects on Ku DNA binding, DNA-PKcs, and DNA end-joining activities, which results in loss of c-Myc's ability to block DSB repair and V(D)J recombination. Interestingly, c-Myc directly disrupts the Ku/DNA-PKcs complex in vitro and in vivo. Thus, c-Myc suppression of DSB repair and V(D)J recombination may occur through inhibition of the nonhomologous end-joining pathway, which provides insight into the mechanism of c-Myc in the development of tumors through promotion of genomic instability. PMID:23308051

  20. Brief inactivation of c-Myc is not sufficient for sustained regression of c-Myc-induced tumours of pancreatic islets and skin epidermis

    Directory of Open Access Journals (Sweden)

    Zervou Sevasti

    2004-12-01

    Full Text Available Abstract Background Tumour regression observed in many conditional mouse models following oncogene inactivation provides the impetus to develop, and a platform to preclinically evaluate, novel therapeutics to inactivate specific oncogenes. Inactivating single oncogenes, such as c-Myc, can reverse even advanced tumours. Intriguingly, transient c-Myc inactivation proved sufficient for sustained osteosarcoma regression; the resulting osteocyte differentiation potentially explaining loss of c-Myc's oncogenic properties. But would this apply to other tumours? Results We show that brief inactivation of c-Myc does not sustain tumour regression in two distinct tissue types; tumour cells in pancreatic islets and skin epidermis continue to avoid apoptosis after c-Myc reactivation, by virtue of Bcl-xL over-expression or a favourable microenvironment, respectively. Moreover, tumours progress despite reacquiring a differentiated phenotype and partial loss of vasculature during c-Myc inactivation. Interestingly, reactivating c-Myc in β-cell tumours appears to result not only in further growth of the tumour, but also re-expansion of the accompanying angiogenesis and more pronounced β-cell invasion (adenocarcinoma. Conclusions Given that transient c-Myc inactivation could under some circumstances produce sustained tumour regression, the possible application of this potentially less toxic strategy in treating other tumours has been suggested. We show that brief inactivation of c-Myc fails to sustain tumour regression in two distinct models of tumourigenesis: pancreatic islets and skin epidermis. These findings challenge the potential for cancer therapies aimed at transient oncogene inactivation, at least under those circumstances where tumour cell differentiation and alteration of epigenetic context fail to reinstate apoptosis. Together, these results suggest that treatment schedules will need to be informed by knowledge of the molecular basis and

  1. Small Molecules Targeting c-Myc Oncogene: Promising Anti-Cancer Therapeutics

    Science.gov (United States)

    Chen, Bing-Jia; Wu, Yan-Ling; Tanaka, Yoshimasa; Zhang, Wen

    2014-01-01

    The nuclear transcription factor c-Myc is a member of the Myc gene family with multiple functions and located on band q24.1 of chromosome 8. The c-Myc gene is activated by chromosomal translocation, rearrangement, and amplification. Its encoded protein transduces intracellular signals to the nucleus, resulting in the regulation of cell proliferation, differentiation, and apoptosis, and has the ability to transform cells and bind chromosomal DNA. c-Myc also plays a critical role in malignant transformation. The abnormal over-expression of c-Myc is frequently observed in some tumors, including carcinomas of the breast, colon, and cervix, as well as small-cell lung cancer, osteosarcomas, glioblastomas, and myeloid leukemias, therefore making it a possible target for anticancer therapy. In this minireview, we summarize unique characteristics of c-Myc and therapeutic strategies against cancer using small molecules targeting the oncogene, and discuss the prospects in the development of agents targeting c-Myc, in particular G-quadruplexes formed in c-Myc promoter and c-Myc/Max dimerization. Such information will be of importance for the research and development of c-Myc-targeted drugs. PMID:25332683

  2. The Essential Cofactor TRRAP Recruits the Histone Acetyltransferase hGCN5 to c-Myc

    Science.gov (United States)

    McMahon, Steven B.; Wood, Marcelo A.; Cole, Michael D.

    2000-01-01

    The c-Myc protein functions as a transcription factor to facilitate oncogenic transformation; however, the biochemical and genetic pathways leading to transformation remain undefined. We demonstrate here that the recently described c-Myc cofactor TRRAP recruits histone acetylase activity, which is catalyzed by the human GCN5 protein. Since c-Myc function is inhibited by recruitment of histone deacetylase activity through Mad family proteins, these opposing biochemical activities are likely to be responsible for the antagonistic biological effects of c-Myc and Mad on target genes and ultimately on cellular transformation. PMID:10611234

  3. A natural small molecule, catechol, induces c-Myc degradation by directly targeting ERK2 in lung cancer

    Science.gov (United States)

    Lim, Do Young; Shin, Seung Ho; Lee, Mee-Hyun; Malakhova, Margarita; Kurinov, Igor; Wu, Qiong; Xu, Jinglong; Jiang, Yanan; Dong, Ziming; Liu, Kangdong; Lee, Kun Yeong; Bae, Ki Beom; Choi, Bu Young; Deng, Yibin; Bode, Ann; Dong, Zigang

    2016-01-01

    Various carcinogens induce EGFR/RAS/MAPK signaling, which is critical in the development of lung cancer. In particular, constitutive activation of extracellular signal-regulated kinase 2 (ERK2) is observed in many lung cancer patients, and therefore developing compounds capable of targeting ERK2 in lung carcinogenesis could be beneficial. We examined the therapeutic effect of catechol in lung cancer treatment. Catechol suppressed anchorage-independent growth of murine KP2 and human H460 lung cancer cell lines in a dose-dependent manner. Catechol inhibited ERK2 kinase activity in vitro, and its direct binding to the ERK2 active site was confirmed by X-ray crystallography. Phosphorylation of c-Myc, a substrate of ERK2, was decreased in catechol-treated lung cancer cells and resulted in reduced protein stability and subsequent down-regulation of total c-Myc. Treatment with catechol induced G1 phase arrest in lung cancer cells and decreased protein expression related to G1-S progression. In addition, we showed that catechol inhibited the growth of both allograft and xenograft lung cancer tumors in vivo. In summary, catechol exerted inhibitory effects on the ERK2/c-Myc signaling axis to reduce lung cancer tumor growth in vitro and in vivo, including a preclinical patient-derived xenograft (PDX) model. These findings suggest that catechol, a natural small molecule, possesses potential as a novel therapeutic agent against lung carcinogenesis in future clinical approaches. PMID:27167001

  4. A natural small molecule, catechol, induces c-Myc degradation by directly targeting ERK2 in lung cancer.

    Science.gov (United States)

    Lim, Do Young; Shin, Seung Ho; Lee, Mee-Hyun; Malakhova, Margarita; Kurinov, Igor; Wu, Qiong; Xu, Jinglong; Jiang, Yanan; Dong, Ziming; Liu, Kangdong; Lee, Kun Yeong; Bae, Ki Beom; Choi, Bu Young; Deng, Yibin; Bode, Ann; Dong, Zigang

    2016-06-07

    Various carcinogens induce EGFR/RAS/MAPK signaling, which is critical in the development of lung cancer. In particular, constitutive activation of extracellular signal-regulated kinase 2 (ERK2) is observed in many lung cancer patients, and therefore developing compounds capable of targeting ERK2 in lung carcinogenesis could be beneficial. We examined the therapeutic effect of catechol in lung cancer treatment. Catechol suppressed anchorage-independent growth of murine KP2 and human H460 lung cancer cell lines in a dose-dependent manner. Catechol inhibited ERK2 kinase activity in vitro, and its direct binding to the ERK2 active site was confirmed by X-ray crystallography. Phosphorylation of c-Myc, a substrate of ERK2, was decreased in catechol-treated lung cancer cells and resulted in reduced protein stability and subsequent down-regulation of total c-Myc. Treatment with catechol induced G1 phase arrest in lung cancer cells and decreased protein expression related to G1-S progression. In addition, we showed that catechol inhibited the growth of both allograft and xenograft lung cancer tumors in vivo. In summary, catechol exerted inhibitory effects on the ERK2/c-Myc signaling axis to reduce lung cancer tumor growth in vitro and in vivo, including a preclinical patient-derived xenograft (PDX) model. These findings suggest that catechol, a natural small molecule, possesses potential as a novel therapeutic agent against lung carcinogenesis in future clinical approaches.

  5. c-myc down-regulation induces apoptosis in human cancer cell lines exposed to RPR-115135 (C31H29NO4), a non-peptidomimetic farnesyltransferase inhibitor.

    Science.gov (United States)

    Russo, Patrizia; Arzani, Dario; Trombino, Sonya; Falugi, Carla

    2003-01-01

    A therapeutic strategy that relies on the use of c-myc antisense in combination with a farnesyltransferase inhibitor, RPR-115135 (C31H29NO4), was studied in human cancer cell lines carrying different mutations (Ras, p53, myc amplification). Cell proliferation was strongly inhibited by the combination and was observed when c-myc oligo (at a concentration that down-regulates c-myc expression) was followed by RPR-115135. Cell cycle analysis demonstrated an accumulation in G0-G1 phase and a tendency to apoptosis (not detectable in cells treated with a single agent). Morphological examination and DNA fragmentation assays (filter binding and enzyme-linked immunosorbent assay DNA fragmentation) confirmed the induction of apoptosis. Apoptosis was not p53- and/or p21(waf-1)-dependent, and the key effector was caspase activation. The combination induced Bax expression and Bcl-2 inhibition. Down-regulation of c-myc amplification carried out a specific role exclusively when Ras was mutated. Exposure of human proliferating lymphocytes to combination did not result in cytotoxicity, suggesting that mechanisms regulating c-myc gene expression during normal T cell proliferation might not be involved. Because of the high percentage of human tumors overexpressing c-myc mRNA and/or protein and, simultaneously, harboring oncogenic Ras mutants (i.e., colon cancers), interrupting the myc- and Ras-signaling pathway would be one of the major focuses on therapy of these types of tumors.

  6. Physiological Expression and Accumulation of the Products of Two Upstream Open Reading Frames mrtl and MycHex1 Along With p64 and p67 Myc From the Human c-myc Locus.

    Science.gov (United States)

    Ji, Mi Hong; Kim, Seung-Ki; Kim, Chae-Yong; Phi, Ji Hoon; Jun, Hyun Jin; Blume, Scott W; Choi, Hyoung Soo

    2016-06-01

    In addition to the canonical c-Myc p64 and p67 proteins, the human c-myc locus encodes two distinct proteins, mrtl (myc-related translation/localization regulatory factor) and MycHex1 (Myc Human Exon 1), from the upstream open reading frames within the 5'-untranslated region of the c-myc P0 mRNA. The aim of this study is to examine simultaneously, for the first time, mrtl, MycHex1, c-Myc p64, and p67 in human tumor cell lines and pediatric brain tumor tissues. Western blot analysis demonstrated endogenous mrtl, MycHex1, c-Myc p64, and p67 simultaneously. The relative abundance of mrtl and MycHex1 were consistent among a variety of human tumor cell lines, and the relative intensities of mrtl and MycHex1 correlated positively. Confocal imaging revealed mrtl predominantly localized to the nuclear envelope, along with prominent reticular pattern in the cytoplasm. MycHex1 was observed as a series of bright foci located within the nucleus, a subset of which colocalized with fibrillarin. mrtl and MycHex1 co-immunoprecipitated with RACK1, c-Myc, fibrillarin, coilin, and with each other. These findings suggest that mrtl and MycHex1 have multiple interaction partners in both the nucleus and cytoplasm. Sequence analyses confirmed a known polymorphism of mrtl at base 1965 (G>T) and new mutations at bases 1900 (C>G) and 1798 (C>G). Evidence is presented for expression and stable accumulation of all four proteins encoded by three distinct non-overlapping open reading frames within the human c-myc locus. Additional work is warranted to further elucidate the functional or regulatory roles of these molecules in regulation of c-Myc and in oncogenesis.

  7. c-myc in Kaposi's sarcoma: analyses by fluorescent in situ hybridization and immunohistochemistry.

    Science.gov (United States)

    Feller, K; Yang, S; Tung, N; Lee, J; Mahalingam, M

    2014-01-01

    The c-myc proto-oncogene plays a central role in the regulation of cellular transcription, differentiation, and apoptosis, and has been shown to be deregulated in many types of human cancer. Recent findings have demonstrated its amplification in select vascular neoplasms, such as secondary angiosarcomas, suggesting a role in angiogenesis as well. In vitro studies have shown that the c-Myc protein is an important regulatory molecule of spindle cell proliferation and migration in Kaposi's sarcoma (KS). In light of these findings, our primary aim was to ascertain whether c-myc, by promoting proliferation and angiogenesis, is an essential co-factor in the aetiopathogenesis of KS. We also attempted to determine a correlation between immunohistochemical expression of the c-Myc protein and c-myc gene copy amplification using fluorescent in situ hybridization (FISH). Samples analyzed included archival tissue of KS (n = 24). PCR for detection of Kaposi's sarcoma-associated herpesvirus DNA was performed on all samples of KS. For FISH analyses, a dual-labelled technique was employed and probes for the c-myc gene and chromosome 8 were used. The monoclonal anti-c-myc antibody, 9E10, was used for immunohistochemical analyses. While FISH analyses revealed no amplification of c-myc in any of the cases of KS, immunohistochemical analyses revealed positive staining for c-Myc in 13/24 cases (54%). Amplification of the c-myc gene was not witnessed in this preliminary study of 24 cases and thus cannot be correlated with the expression of the c-Myc protein. © 2012 The Authors. Journal of the European Academy of Dermatology and Venereology © 2012 European Academy of Dermatology and Venereology.

  8. [Effect of Helicobacter pylori eradication on the expression level of SATB1 and c-Myc genes in gastric mucosa of patients with family history of gastric cancer].

    Science.gov (United States)

    Tracz, Adam F; Peczek, Łukasz; Zuk, Karolina; Stec-Michalska, Krystyna; Nawrot, Barbara

    2013-05-01

    Helicobacter pylori (H. pylori) is a class 1 gastric carcinogen with the proved influence on gastric cancer development. The products of SATB1 and c-Myc genes play important role in cancer development and their levels are elevated in gastric cancer tissues. The aim of the study was to analyze an effect of H. pylori eradication on the expression of the SATB1 and c-Myc genes in the gastric mucosa of dyspeptic patients with family history of gastric cancer. Twenty patients enrolled to the studies were divided into two groups: nine patients (group I) without the family history of gastric cancer, and eleven patients with the family history of gastric cancer (group II). Endoscopic biopsies of gastric mucosa were taken from the antrum and corpus of H. pylori-infected subjects before and after bacteria eradication. The corresponding levels of expression were determined by analysis of the respective mRNA levels with the use of the real-time RT-PCR method. The level of each mRNA was normalized to the levels of mRNA of two reference genes, RPL29 and GAPDH. Independently of stomach topography, the antrum versus corpus, in the group I patients the levels of mRNA of SATB1 and c-Myc after eradication were higher in the following cases: SATB1/ GAPDH p = 0.017914 (antrum); SATB1/RPL29 p = 0.046400 (corpus); SATB1/GAPDH p = 0.027709 (corpus). For group II patients no statistically significant increase of the level of the c-Myc and SATB1 genes was observed. Patients with the family history of gastric cancer and H. pylori infection, with reversible histopathological changes of the gastric mucosa, have significantly higher levels of SATB1 and c-Myc genes expression as compared to the patients without family history of gastric cancer, regardless of the topography of the stomach. After successful eradication, the SATB1 mRNA level in samples of patients with the family history of gastric cancer did not increase, in contrast to the control group of patients. Presumably, the observed effect

  9. Acetylation of the c-MYC oncoprotein is required for cooperation with the HTLV-1 p30{sup II} accessory protein and the induction of oncogenic cellular transformation by p30{sup II}/c-MYC

    Energy Technology Data Exchange (ETDEWEB)

    Romeo, Megan M.; Ko, Bookyung; Kim, Janice; Brady, Rebecca; Heatley, Hayley C.; He, Jeffrey; Harrod, Carolyn K.; Barnett, Braden [Laboratory of Molecular Virology, Department of Biological Sciences, and The Dedman College Center for Drug Discovery, Design, and Delivery, Southern Methodist University, Dallas, TX 75275-0376 (United States); Ratner, Lee [Departments of Medicine and Molecular Microbiology, Washington University School of Medicine, St. Louis, MO 63110 (United States); Lairmore, Michael D. [University of California-Davis, School of Veterinary Medicine, One Shields Avenue, Davis, CA 95618 (United States); Martinez, Ernest [Department of Biochemistry, University of California, Riverside, CA 92521 (United States); Lüscher, Bernhard [Institute of Biochemistry, Klinikum, RWTH Aachen University, Pauwelsstrasse 30, 52057 Aachen (Germany); Robson, Craig N. [Northern Institute for Cancer Research, Newcastle University, The Medical School, Newcastle upon Tyne, NE2 4HH (United Kingdom); Henriksson, Marie [Department of Microbiology, Cell and Tumor Biology, Karolinska Institutet, Stockholm (Sweden); Harrod, Robert, E-mail: rharrod@smu.edu [Laboratory of Molecular Virology, Department of Biological Sciences, and The Dedman College Center for Drug Discovery, Design, and Delivery, Southern Methodist University, Dallas, TX 75275-0376 (United States)

    2015-02-15

    The human T-cell leukemia retrovirus type-1 (HTLV-1) p30{sup II} protein is a multifunctional latency-maintenance factor that negatively regulates viral gene expression and deregulates host signaling pathways involved in aberrant T-cell growth and proliferation. We have previously demonstrated that p30{sup II} interacts with the c-MYC oncoprotein and enhances c-MYC-dependent transcriptional and oncogenic functions. However, the molecular and biochemical events that mediate the cooperation between p30{sup II} and c-MYC remain to be completely understood. Herein we demonstrate that p30{sup II} induces lysine-acetylation of the c-MYC oncoprotein. Acetylation-defective c-MYC Lys→Arg substitution mutants are impaired for oncogenic transformation with p30{sup II} in c-myc{sup −/−} HO15.19 fibroblasts. Using dual-chromatin-immunoprecipitations (dual-ChIPs), we further demonstrate that p30{sup II} is present in c-MYC-containing nucleoprotein complexes in HTLV-1-transformed HuT-102 T-lymphocytes. Moreover, p30{sup II} inhibits apoptosis in proliferating cells expressing c-MYC under conditions of genotoxic stress. These findings suggest that c-MYC-acetylation is required for the cooperation between p30{sup II}/c-MYC which could promote proviral replication and contribute to HTLV-1-induced carcinogenesis. - Highlights: • Acetylation of c-MYC is required for oncogenic transformation by HTLV-1 p30{sup II}/c-MYC. • Acetylation-defective c-MYC mutants are impaired for foci-formation by p30{sup II}/c-MYC. • The HTLV-1 p30{sup II} protein induces lysine-acetylation of c-MYC. • p30{sup II} is present in c-MYC nucleoprotein complexes in HTLV-1-transformed T-cells. • HTLV-1 p30{sup II} inhibits apoptosis in c-MYC-expressing proliferating cells.

  10. Regulation of human ornithine decarboxylase expression following prolonged quiescence: role for the c-Myc/Max protein complex.

    Science.gov (United States)

    Peña, A; Wu, S; Hickok, N J; Soprano, D R; Soprano, K J

    1995-02-01

    WI-38 cells can remain quiescent for long periods of time and still be induced to reenter the cell cycle by the addition of fresh serum. However, the longer these cells remain growth arrested, the more time they require to enter S phase. This prolongation of the prereplicative phase has been localized to a point early in G1, after the induction of "immediate early" G1 genes such as c-fos and c-jun but before maximal expression of "early" G1 genes such as ornithine decarboxylase (ODC). Understanding the molecular basis for ODC mRNA induction can therefore provide information about the molecular events which regulate the progression of cells out of long-term quiescence into G1 and subsequently into DNA synthesis. Studies utilizing electrophoretic mobility shift assays (EMSA) of nuclear extracts from short- and long-term quiescent WI-38 cells identified a region of the human ODC promoter at -491 bp to -474 bp which exhibited a protein binding pattern that correlated with the temporal pattern of ODC mRNA expression. The presence of a CACGTG element within this fragment, studies with antibodies against c-Myc and Max, the use of purified recombinant c-Myc protein in the mobility shift assay, and antisense studies suggest that these proteins can specifically bind this portion of the human ODC promoter in a manner consistent with growth-associated modulation of the expression of ODC and other early G1 genes following prolonged quiescence. These studies suggest a role for the c-Myc/Max protein complex in regulating events involved in the progression of cells out of long-term quiescence into G1 and subsequently into S.

  11. Effect of C-myc Antisense Oligodeoxynucleotides on Hypoxia-induced Proliferation of Pulmonary Vascular Pericytes

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    To study the effect of c-myc antisense oligodeoxynucleotides (ODNs) on proliferation of pulmonary vascular pericytes (PC) induced by hypoxia, cell culture, dot hybridization using probe of digoxigenin-11-dUTP-labeled cDNA,3H-thymidine incorporation, immunocytochemical technique and image analysis methods were used to observe the effect of c-myc antisense ODNs on expression of c-myc gene and proliferating cell nuclear antigen (PCNA), and 3H-thymidine incorporation of PC induced by hypoxia. The results showed that hypoxia could significantly enhance the expression of c-myc and PCNA (P<0.01), and elevate 3H-thymidine incorporation of PC (P<0.01), but antisense ODNs could significantly inhibit the expression of c-myc and PCNA (P<0.05), and 3H-thymidine incorporation of PC (P<0.01). It was suggested that hypoxia could promote the proliferation of PC by up-regulating the expression of c-myc gene, but c-myc antisense ODNs could inhibit hypoxia-induced proliferation of PC by downregulating the expression of c-myc gene.

  12. Deregulation of c-myc and SV40Tag causing brain tumor in mice

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Deregulated expressions of both c-myc and simian virus 40 large T antigen (SV40Tag) are consistent features of lots of tumors. To investigate whether the expression of c-myc and SV40Tag in mouse might help develop a model of human tumor, we generated c-myc transgenics by inserting human c-myc gene into pTRE2 of Tet-On system. We obtained conditional expression of SV40Tag transgenics by the Tet-On system from Yangzhou University. Crossing the c-myc transgenic mouse with the SV40Tag transgenic mice to generate bitransgenics we got double-transgenic mice expressing c-myc and SV40Tag by the Tet-On system. After being treated with doxycycline continuously, single-transgenic SV40Tag mice developed brain tumor infrequently (3 of 84, 3.6%) with a long onset (185 d on average). In contrast, double-transgenic c-myc/SV40Tag mice developed brain tumor with a short onset (96 days on average) and a 41% brain tumor incidence rate (7 of 17, 41%). This tumor was assumed to be medulloblastoma. Our experiments suggest that deregulated expression of c-myc and SV40Tag in brain might generate a mouse model of human brain tumor that recapitulates some features of human medulloblastoma.

  13. Glutathione Depletion Induced by c-Myc Downregulation Triggers Apoptosis on Treatment with Alkylating Agents

    Directory of Open Access Journals (Sweden)

    Annamaria Biroccio

    2004-05-01

    Full Text Available Here we investigate the mechanism(s involved in the c-Myc-dependent drug response of melanoma cells. By using three M14-derived c-Myc low-expressing clones, we demonstrate that alkylating agents, cisplatin and melphalan, trigger apoptosis in the c-Myc antisense transfectants, but not in the parental line. On the contrary, topoisomerase inhibitors, adriamycin and camptothecin, induce apoptosis to the same extent regardless of c-Myc expression. Because we previously demonstrated that c-Myc downregulation decreases glutathione (GSH content, we evaluated the role of GSH in the apoptosis induced by the different drugs. In control cells treated with one of the alkylating agents or the others, GSH depletion achieved by L-buthionine-sulfoximine preincubation opens the apoptotic pathway. The apoptosis proceeded through early Bax relocalization, cytochrome c release, concomitant caspase-9 activation, whereas reactive oxygen species production and alteration of mitochondria membrane potential were late events. That GSH was determining in the c-Myc-dependent druginduced apoptosis was demonstrated by altering the intracellular GSH content of the c-Myc low-expressing cells up to the level of controls. Indeed, GSH ethyl ester-mediated increase of GSH abrogated apoptosis induced by cisplatin and melphalan by inhibition of Baxicytochrome c redistribution. The relationship among c-Myc, GSH content, the response to alkylating agent has been also evaluated in the M14 Myc overexpressing clones as well as in the melanoma JR8 c-Myc antisense transfectants. All together, these results demonstrate that GSH plays a key role in governing c-Myc-dependent drug-induced apoptosis.

  14. Microwave-assisted synthesis of ruthenium(II) complexes with alkynes as potential inhibitor by selectively recognizing c-myc G-quadruplex DNA.

    Science.gov (United States)

    Zhang, Shuangyan; Wu, Qiong; Zhang, Hao; Wang, Qi; Wang, Xicheng; Mei, Wenjie; Wu, Xiaohui; Zheng, Wenjie

    2017-11-01

    Herein, two polypyridyl ruthenium(II) complexes with alkynes, [Ru(bpy)2L](ClO4)2 (L=p-TEPIP (1) and p-BEPIP (2); bpy=2,2'-bipyridine; p-TEPIP=2-(4-trimethylsilylpropargyl)-1H-imidazo[4,5f][1,10]phenanthroline; p-BEPIP=2-(4-phenyacetylenephenyl)-1H-imidazo[4,5f][1,10]phenanthroline) have been successfully achieved in yields of 32%-89% by a Sonogashira coupling reaction under microwave irradiation. We studied these complexes as potential stabilizers of c-myc G-quadruplex DNA. Observations revealed that both complexes could selectively bind to and stabilize c-myc G-quadruplex DNA with a constant of approximately 1.61±0.78 and 9.47±4.20×10(3)M(-1), respectively, as determined from ITC (isothermal ttitration calorimetry) experiments, FRET (fluorescence resonance energy ttransfer) assay and competitive FRET assay. Moreover, the melting point (Tm) of the c-myc G-quadruplex DNA increased in the presence of 1 and 2 ([Ru]=0.2μM) by approximately 9 and 19.9°C, respectively. It is noteworthy that the conformation of the c-myc G-quadruplex DNA appeared to change when titrated with 1 and 2, which was accompanied by a negative-induced CD (circular dichroism) signal that appeared at a wavelength of 295nm. Furthermore, the conformational change in c-myc G-quadruplex DNA induced by 1 and 2have also been confirmed by TEM (transmission electron microscopy) and AFM (atomic force microscopy). Consequently, the replication of c-myc DNA was blocked by 1 and 2, and especially by 2, as verified by PCR (polymerase chain reaction) -stop assay and Western-blot assay. Thus, these ruthenium(II) complexes can be developed as potential inhibitors in chemotherapy through their binding and stabilization of c-myc G-quadruplex DNA. Copyright © 2017 Elsevier Inc. All rights reserved.

  15. TELOMERASE ACTIVITY IN COLORECTAL CARCINOMA AND ITS CORRELATION WITH EXPRESSION OF C-MYC

    Institute of Scientific and Technical Information of China (English)

    LIU Jian-Lun; GE Lian-ying; ZHANG Gui-nian

    2005-01-01

    Objective: To study the role of telomerase activity and c-myc in pathogenesis and progression of colorectal carcinoma,and to investigate the possible regulatory mechanism of telomerase activation. Methods: A modified telomeric repeat amplification protocol (TRAP) and immunohistochemical staining was used to detect telomerase activity and the expression of c-myc in tissue samples from colorectal carcinoma, paracarcinomatousl tissues, normal mucosa, and adenomatoid polyp.Results: The positive rates of telomerase activity and c-myc expression were 83.33% and 80.00% in colorectal carcinoma,13.33% and 23.33% in paracarcinomatousl tissues, 13.33% and 20.00% in normal mucosa, and 10.00% and 45.00% in adenomatoid polyp respectively, they were significantly higher in colorectal carcinoma than in paracarcinomatousl tissues,normal mucosa, and adenomatoid polyp (P<0.05). The rates of telomerase activity and c-myc expression were much higher in colorectal carcinoma with lymph nodes metastases than that without lymph nodes metastases. The expression of c-myc was found being significantly higher in the telomerase positive colorectal carcinoma than in the telomerase negative group(P<0.05). Conclusion: The activation of telomerase and abnormal expression of c-myc might play an important role in the process of carcinogenesis and progression of colorectal carcinoma. The over-expression of c-myc may be related to telomerase activation and up-regulation in colorectal carcinoma.

  16. Sulforaphane Inhibits c-Myc-Mediated Prostate Cancer Stem-Like Traits.

    Science.gov (United States)

    Vyas, Avani R; Moura, Michelle B; Hahm, Eun-Ryeong; Singh, Krishna Beer; Singh, Shivendra V

    2016-11-01

    Preventive and therapeutic efficiencies of dietary sulforaphane (SFN) against human prostate cancer have been demonstrated in vivo, but the underlying mechanism(s) by which this occurs is poorly understood. Here, we show that the prostate cancer stem cell (pCSC)-like traits, such as accelerated activity of aldehyde dehydrogenase 1 (ALDH1), enrichment of CD49f+ fraction, and sphere forming efficiency, are attenuated by SFN treatment. Interestingly, the expression of c-Myc, an oncogenic transcription factor that is frequently deregulated in prostate cancer cells, was markedly suppressed by SFN both in vitro and in vivo. This is biologically relevant, because the lessening of pCSC-like phenotypes mediated by SFN was attenuated when c-Myc was overexpressed. Naturally occurring thio, sulfinyl, and sulfonyl analogs of SFN were also effective in causing suppression of c-Myc protein level. However, basal glycolysis, a basic metabolic pathway that can also be promoted by c-Myc overexpression, was not largely suppressed by SFN, implying that, in addition to c-Myc, there might be another SFN-sensitive cellular factor, which is not directly involved in basal glycolysis, but cooperates with c-Myc to sustain pCSC-like phenotypes. Our study suggests that oncogenic c-Myc is a target of SFN to prevent and eliminate the onset of human prostate cancer. J. Cell. Biochem. 117: 2482-2495, 2016. © 2016 Wiley Periodicals, Inc.

  17. A genetic screen to identify genes that rescue the slow growth phenotype of c-myc null fibroblasts

    NARCIS (Netherlands)

    Berns, K.; Hijmans, E.M.; Koh, E.; Daley, G.Q.; Bernards, R.A.

    2000-01-01

    The c-myc gene is frequently over-expressed in human cancers and is involved in regulation of proliferation, differentiation and apoptosis. c-Myc is a transcription factor that acts primarily by regulating the expression of other genes. However, it has been very difficult to identify bona fide c-Myc

  18. c-Myc Alteration Determines the Therapeutic Response to FGFR Inhibitors.

    Science.gov (United States)

    Liu, Hongyan; Ai, Jing; Shen, Aijun; Chen, Yi; Wang, Xinyi; Peng, Xia; Chen, Hui; Shen, Yanyan; Huang, Min; Ding, Jian; Geng, Meiyu

    2017-02-15

    Purpose: Lately, emerging evidence has suggested that oncogenic kinases are associated with specific downstream effectors to govern tumor growth, suggesting potential translational values in kinase-targeted cancer therapy. Tyrosine kinase FGFR, which is aberrant in various cancer types, is one of the most investigated kinases in molecularly targeted cancer therapy. Herein, we investigated whether there exists key downstream effector(s) that converges FGFR signaling and determines the therapeutic response of FGFR-targeted therapy.Experimental Design: A range of assays was used to assess the role of c-Myc in FGFR aberrant cancers and its translational relevance in FGFR-targeted therapy, including assessment of drug sensitivity using cell viability assay, signaling transduction profiling using immunoblotting, and in vivo antitumor efficacy using cancer cell line-based xenografts and patient-derived xenografts models.Results: We discovered that c-Myc functioned as the key downstream effector that preceded FGFR-MEK/ERK signaling in FGFR aberrant cancer. Disruption of c-Myc overrode the cell proliferation driven by constitutively active FGFR. FGFR inhibition in FGFR-addicted cancer facilitated c-Myc degradation via phosphorylating c-Myc at threonine 58. Ectopic expression of undegradable c-Myc mutant conferred resistance to FGFR inhibition both in vitro and in vivo c-Myc level alteration stringently determined the response to FGFR inhibitors, as demonstrated in FGFR-responsive cancer subset, as well as cancers bearing acquired or de novo resistance to FGFR inhibition.Conclusions: This study reveals a stringent association between FGFR and the downstream effector c-Myc in FGFR-dependent cancers, and suggests the potential therapeutic value of c-Myc in FGFR-targeted cancer therapy. Clin Cancer Res; 23(4); 974-84. ©2016 AACR.

  19. c-Myc is essential to prevent endothelial pro-inflammatory senescent phenotype.

    Directory of Open Access Journals (Sweden)

    Victoria Florea

    Full Text Available The proto-oncogene c-Myc is vital for vascular development and promotes tumor angiogenesis, but the mechanisms by which it controls blood vessel growth remain unclear. In the present work we investigated the effects of c-Myc knockdown in endothelial cell functions essential for angiogenesis to define its role in the vasculature. We provide the first evidence that reduction in c-Myc expression in endothelial cells leads to a pro-inflammatory senescent phenotype, features typically observed during vascular aging and pathologies associated with endothelial dysfunction. c-Myc knockdown in human umbilical vein endothelial cells using lentivirus expressing specific anti-c-Myc shRNA reduced proliferation and tube formation. These functional defects were associated with morphological changes, increase in senescence-associated-β-galactosidase activity, upregulation of cell cycle inhibitors and accumulation of c-Myc-deficient cells in G1-phase, indicating that c-Myc knockdown in endothelial cells induces senescence. Gene expression analysis of c-Myc-deficient endothelial cells showed that senescent phenotype was accompanied by significant upregulation of growth factors, adhesion molecules, extracellular-matrix components and remodeling proteins, and a cluster of pro-inflammatory mediators, which include Angptl4, Cxcl12, Mdk, Tgfb2 and Tnfsf15. At the peak of expression of these cytokines, transcription factors known to be involved in growth control (E2f1, Id1 and Myb were downregulated, while those involved in inflammatory responses (RelB, Stat1, Stat2 and Stat4 were upregulated. Our results demonstrate a novel role for c-Myc in the prevention of vascular pro-inflammatory phenotype, supporting an important physiological function as a central regulator of inflammation and endothelial dysfunction.

  20. c-Myc is essential to prevent endothelial pro-inflammatory senescent phenotype.

    Science.gov (United States)

    Florea, Victoria; Bhagavatula, Nithya; Simovic, Gordana; Macedo, Francisco Y; Fock, Ricardo A; Rodrigues, Claudia O

    2013-01-01

    The proto-oncogene c-Myc is vital for vascular development and promotes tumor angiogenesis, but the mechanisms by which it controls blood vessel growth remain unclear. In the present work we investigated the effects of c-Myc knockdown in endothelial cell functions essential for angiogenesis to define its role in the vasculature. We provide the first evidence that reduction in c-Myc expression in endothelial cells leads to a pro-inflammatory senescent phenotype, features typically observed during vascular aging and pathologies associated with endothelial dysfunction. c-Myc knockdown in human umbilical vein endothelial cells using lentivirus expressing specific anti-c-Myc shRNA reduced proliferation and tube formation. These functional defects were associated with morphological changes, increase in senescence-associated-β-galactosidase activity, upregulation of cell cycle inhibitors and accumulation of c-Myc-deficient cells in G1-phase, indicating that c-Myc knockdown in endothelial cells induces senescence. Gene expression analysis of c-Myc-deficient endothelial cells showed that senescent phenotype was accompanied by significant upregulation of growth factors, adhesion molecules, extracellular-matrix components and remodeling proteins, and a cluster of pro-inflammatory mediators, which include Angptl4, Cxcl12, Mdk, Tgfb2 and Tnfsf15. At the peak of expression of these cytokines, transcription factors known to be involved in growth control (E2f1, Id1 and Myb) were downregulated, while those involved in inflammatory responses (RelB, Stat1, Stat2 and Stat4) were upregulated. Our results demonstrate a novel role for c-Myc in the prevention of vascular pro-inflammatory phenotype, supporting an important physiological function as a central regulator of inflammation and endothelial dysfunction.

  1. Nuclear localization of phosphorylated c-Myc protein in human tumor cells.

    Directory of Open Access Journals (Sweden)

    C. Soldani

    2010-05-01

    Full Text Available Using immunocytochemical techniques at light and electron microscopy, we analysed the distribution of phosphorylated c-Myc in actively proliferating human HeLa cells. The distribution pattern of c-Myc was also compared with those of other ribonucleoprotein (RNP-containing components (PANA, hnRNP-core proteins, fibrillarin or RNP-associated nuclear proteins (SC-35 splicing factor. Our results provide the first evidence that phosphorylated c-Myc accumulates in the nucleus of tumor cells, where it colocalizes with fibrillarin, both in the nucleolus and in extranucleolar structures.

  2. Radiosensitivity of small-cell lung cancer xenografts compared with activity of c-myc, N-myc, L-myc, c-raf-1 and K-ras proto-oncogenes

    DEFF Research Database (Denmark)

    Rygaard, K; Slebos, R J; Spang-Thomsen, M

    1991-01-01

    than CPH-54B, while, with respect to the 3 GLC tumours examined, GLC-16 was most sensitive, followed by GLC-14 and GLC-19. The CPH tumours expressed similar amounts of c-myc and c-raf-1 mRNA, and neither expressed N-myc or L-myc. GLC-14 expressed N-myc and c-raf-1 mRNA but no c-myc. GLC-16 and GLC-19...... expressed identical amounts of c-raf-1 and high levels of c-myc mRNA, but neither expressed N-myc or L-myc. None of the tumours was mutated at codon 12 or K-ras. Our results show that SCLC xenografts with different radiosensitivity may express identical amounts of some of the proto-oncogenes reported...... regrowth after single-dose irradiation. No long-term difference in expression of c-raf-1 or c-myc mRNA was detected between control tumours and tumours irradiated with 5 or 10 Gy....

  3. Dinuclear ruthenium complexes display loop isomer selectivity to c-MYC DNA G-quadriplex and exhibit anti-tumour activity.

    Science.gov (United States)

    Zheng, Chuping; Liu, Yanan; Liu, Ying; Qin, Xiuying; Zhou, Yanhui; Liu, Jie

    2016-03-01

    G-quadruplex DNA, especially the cellular-myelocytomatosis viral oncogene (c-MYC) is closely associated with cell-cycle regulation, proliferation of tumour cells. In this work, the interaction between the c-MYC and two dinuclear Ru(II) complexes [(bpy)2Ru(bpibp)Ru(bpy)2](ClO4)4 (compound 1) and [(phen)2Ru(bpibp)Ru(phen)2](ClO4)4 (compound 2) have been studied. The data from UV-Visible, PCR-stop and Fluorescence resonance energy transfer (FRET) showed that two complexes can stabilize the structure of G-quadruplex in the c-MYC promoter and targeting the G-quadruplex loop isomers. Interestingly, the complex 2 has a greater effect on the 1:2:1 and 2:1:1 loop isomers while the 1 prefers to the 1:2:1 isomers. The mechanism studies revealed that complexes can induce apoptosis in HepG2 cells by generating ROS metabolites, triggering mitochondrial membrane potential loss and down-regulation of P-Akt (Akt also known as protein kinase B), P-p44/42 MAP kinase protein (P-p44/42), and c-MYC. Taken together, these results suggested that the two dinuclear complexes may both be candidates as anti-tumour agents as they may reduce the c-MYC gene expression. {bpibp: 4, 4'-bis (1, 10-phenanthroline-[5, 6-d] imidazole-2-yl)-biphenyl, bpy: 2,2-bipyridine, phen: 1,10-phenanthroline}. Copyright © 2016. Published by Elsevier Inc.

  4. AP-2α Inhibits c-MYC Induced Oxidative Stress and Apoptosis in HaCaT Human Keratinocytes

    Directory of Open Access Journals (Sweden)

    Lei Yu

    2009-01-01

    AP-2 may have a direct effect on the c-myc gene. Chromatin immunoprecipitation assays demonstrated that AP-2 proteins bound to a cluster of AP-2 binding sites located within a 2 kb upstream regulatory region of c-myc These results suggest that the negative regulation of AP-2 on c-MYC activity was achieved through binding of AP-2 protein to the c-myc gene. The effects of AP-2 on c-MYC induced ROS accumulation and apoptosis in epidermal keratinocytes are likely to play an important role in cell growth, differentiation and carcinogenesis of the skin.

  5. INCREASED EXPRESSION OF PDGF AND C-MYC GENES IN LUNGS AND PULMONARY ARTERIES OF PULMONARY HYPERTENSIVE RATS INDUCED BY HYPOXIA

    Institute of Scientific and Technical Information of China (English)

    蔡英年; 韩梅; 罗兰; 宋为; 周晓梅

    1996-01-01

    The role of growth factors and proto-oncogene in pulmonary vascular structural remodelling is not well known.The present study examined gene expression of plateler-derived growth factor(PDGF)-A and -B chain and proto-oncogene,c-myc,in lung tissue and pulmonary artery of rats exposed to hypoxia and compred to those levels of gene expression in normal rats.Normal lungs and pulmonary artery expressed PDGF-A chain transcripr of 1.7kb and PDGF-B chain transcript of 3.5 Kb. The c-myc transcript of 2.2 kb was expressed as well.After hypoxic exposure for 7 and 14 days mRNA levels of PDGF-B chain and c-myc were elevated significantly compared with those of control rats.PDGF-A chain mRNA increased after hypoxia for 7 days,and then declined.These results suggest that activation of sutocrine and /or paracrine is important in proliferation mechanism of pulmonary artery smooth muscle cells in bypoxic pulmonary hypertensive rats.

  6. Induction of C-FOS, C-MYC and P53 by US -adrenergic receptor (US -AR) stimulation of rat parotid acinar cells (RPAC)

    Energy Technology Data Exchange (ETDEWEB)

    Kousvelari, E.E.; Louis, J.; Curran, T.; Baum, B.J.

    1987-05-01

    Treatment of rats with the US -agonist isoproterenol (ISO) results in dramatically increased parotid gland protein synthesis, processing and cell proliferation. The authors have shown that in RPAC in vitro, US -AR stimulation has similar effect on protein synthesis and processing. Proto-oncogenes have been implicated in growth regulation, differentiation and in mediating some extracellular stimulated events at the level of gene expression. To understand the regulation of cellular events after US -AR stimulation, the expression of c-fos, c-myc and p53 was investigated. RPAC were incubated with or without 10 VM ISO for 15, 30, 60 min. mRNA was isolated from cells and hybridization analysis was performed on nitrocellulose paper-transferred mRNA using TSP-labeled DNA probes. At early time points, the levels of c-fos gene activation in ISO-treated and control cells were comparable. After 60 min of ISO treatment, a sharp 20-30 fold induction of c-fos expression occurred. Similar increases in c-myc and p53 gene expression were observed after 60 min of ISO treatment. The authors data indicate that early effects of US -AR stimulation of RPAC include induction of c-fos, c-myc and p53 gene expression as well as enhanced protein synthesis and processing.

  7. Anti-proliferative effects of Atractylis lancea (Thunb.) DC. via down-regulation of the c-myc/hTERT/telomerase pathway in Hep-G2 cells.

    Science.gov (United States)

    Guo, Wei-Qiang; Li, Liang-Zhi; He, Zhuo-Yang; Zhang, Qi; Liu, Jia; Hu, Cui-Ying; Qin, Fen-Ju; Wang, Tao-Yun

    2013-01-01

    Atractylis lancea (Thunb.) DC. (AL), an important medicinal herb in Asia, has been shown to have anti-tumor effects on cancer cells, but the involved mechanisms are poorly understood. This study focused on potential effects and molecular mechanisms of AL on the proliferation of the Hep-G2 liver cancer cell line in vitro. Cell viability was assessed by MTT test in Hep-G2 cells incubated with an ethanol extract of AL. Then, the effects of AL on apoptosis and cell cycle progression were determined by flow cytometry. Telomeric repeat amplification protocol (TRAP) assays was performed to investigate telomerase activity. The mRNA and protein expression of human telomerase reverse transcriptase (hTERT) and c-myc were determined by real-time RT-PCR and Western blotting. Our results show that AL effectively inhibits proliferation in Hep-G2 cells in a concentration- and time-dependent manner. When Hep-G2 cells were treated with AL after 48h,the IC50 was about 72.1 μg/ mL. Apoptosis was induced by AL via arresting the cells in the G1 phase. Furthermore, AL effectively reduced telomerase activity through inhibition of mRNA and protein expression of hTERT and c-myc. Hence, these data demonstrate that AL exerts anti-proliferative effects in Hep-G2 cells via down-regulation of the c-myc/hTERT/ telomerase pathway.

  8. Clinicopathologic and prognostic significance of c-MYC copy number gain in lung adenocarcinomas

    Science.gov (United States)

    Seo, A N; Yang, J M; Kim, H; Jheon, S; Kim, K; Lee, C T; Jin, Y; Yun, S; Chung, J-H; Paik, J H

    2014-01-01

    Background: c-MYC copy number gain (c-MYC gain) has been associated with aggressive behaviour in several cancers. However, the role of c-MYC gain has not yet been determined in lung adenocarcinomas classified by genetic alterations in epidermal growth factor receptor (EGFR), KRAS, and anaplastic lymphoma kinase (ALK) genes. We investigated the clinicopathologic and prognostic significance of c-MYC gain for disease-free survival (DFS) and overall survival (OS) according to EGFR, KRAS, and ALK gene status and stages in lung adenocarcinomas. Methods: In 255 adenocarcinomas resected in Seoul National University Bundang Hospital from 2003 to 2009, fluorescence in situ hybridisation (FISH) with c-MYC probe and centromeric enumeration probe 8 (CEP8) was analysed using tissue microarray containing single representative core per each case. EGFR (codon 18 to 21) and KRAS (codon 12, 13, and 61) mutations were analysed by polymerase chain reaction and direct sequencing method from formalin-fixed, paraffin-embedded tissue sections. ALK rearrangement was determined by FISH method. c-MYC gain was defined as >2 copies per nucleus, chromosome 8 gain as ⩾3 copies per nucleus, and gain of c-MYC:CEP8 ratio (hereafter, c-MYC amplification) as ⩾2. Results: We observed c-MYC gain in 20% (51 out of 255), chromosome 8 gain in 5.5% (14 out of 255), c-MYC amplification in 2.4% (6 out of 255), EGFR mutation in 49.4% (118 out of 239), KRAS mutation in 5.7% (7 out of 123), and ALK rearrangement in 4.9% (10 out of 205) of lung adenocarcinomas. c-MYC gain was observed in 19% (22 out of 118) of patients with lung adenocarcinomas with an EGFR mutation, but not in any patients with a KRAS mutation, or an ALK rearrangement. c-MYC gain (but not chromosome 8 gain or c-MYC amplification) was an independent poor-prognostic factor in the full cohort of lung adenocarcinoma (P=0.022, hazard ratio (HR)=1.71, 95% confidence interval (CI), 1.08–2.69 for DFS; P=0.032, HR=2.04, 95% CI, 1.06–3.91 for OS

  9. Therapeutic aspects of c-MYC signaling in inflammatory and cancerous colonic diseases.

    Science.gov (United States)

    Sipos, Ferenc; Firneisz, Gábor; Műzes, Györgyi

    2016-09-21

    Colonic inflammation is required to heal infections, wounds, and maintain tissue homeostasis. As the seventh hallmark of cancer, however, it may affect all phases of tumor development, including tumor initiation, promotion, invasion and metastatic dissemination, and also evasion immune surveillance. Inflammation acts as a cellular stressor and may trigger DNA damage or genetic instability, and, further, chronic inflammation can provoke genetic mutations and epigenetic mechanisms that promote malignant cell transformation. Both sporadical and colitis-associated colorectal carcinogenesis are multi-step, complex processes arising from the uncontrolled proliferation and spreading of malignantly transformed cell clones with the obvious ability to evade the host's protective immunity. In cells upon DNA damage several proto-oncogenes, including c-MYC are activated in parelell with the inactivation of tumor suppressor genes. The target genes of the c-MYC protein participate in different cellular functions, including cell cycle, survival, protein synthesis, cell adhesion, and micro-RNA expression. The transcriptional program regulated by c-MYC is context dependent, therefore the final cellular response to elevated c-MYC levels may range from increased proliferation to augmented apoptosis. Considering physiological intestinal homeostasis, c-MYC displays a fundamental role in the regulation of cell proliferation and crypt cell number. However, c-MYC gene is frequently deregulated in inflammation, and overexpressed in both sporadic and colitis-associated colon adenocarcinomas. Recent results demonstrated that endogenous c-MYC is essential for efficient induction of p53-dependent apoptosis following DNA damage, but c-MYC function is also involved in and regulated by autophagy-related mechanisms, while its expression is affected by DNA-methylation, or histone acetylation. Molecules directly targeting c-MYC, or agents acting on other genes involved in the c-MYC pathway could be

  10. Therapeutic aspects of c-MYC signaling in inflammatory and cancerous colonic diseases

    Science.gov (United States)

    Sipos, Ferenc; Firneisz, Gábor; Műzes, Györgyi

    2016-01-01

    Colonic inflammation is required to heal infections, wounds, and maintain tissue homeostasis. As the seventh hallmark of cancer, however, it may affect all phases of tumor development, including tumor initiation, promotion, invasion and metastatic dissemination, and also evasion immune surveillance. Inflammation acts as a cellular stressor and may trigger DNA damage or genetic instability, and, further, chronic inflammation can provoke genetic mutations and epigenetic mechanisms that promote malignant cell transformation. Both sporadical and colitis-associated colorectal carcinogenesis are multi-step, complex processes arising from the uncontrolled proliferation and spreading of malignantly transformed cell clones with the obvious ability to evade the host’s protective immunity. In cells upon DNA damage several proto-oncogenes, including c-MYC are activated in parelell with the inactivation of tumor suppressor genes. The target genes of the c-MYC protein participate in different cellular functions, including cell cycle, survival, protein synthesis, cell adhesion, and micro-RNA expression. The transcriptional program regulated by c-MYC is context dependent, therefore the final cellular response to elevated c-MYC levels may range from increased proliferation to augmented apoptosis. Considering physiological intestinal homeostasis, c-MYC displays a fundamental role in the regulation of cell proliferation and crypt cell number. However, c-MYC gene is frequently deregulated in inflammation, and overexpressed in both sporadic and colitis-associated colon adenocarcinomas. Recent results demonstrated that endogenous c-MYC is essential for efficient induction of p53-dependent apoptosis following DNA damage, but c-MYC function is also involved in and regulated by autophagy-related mechanisms, while its expression is affected by DNA-methylation, or histone acetylation. Molecules directly targeting c-MYC, or agents acting on other genes involved in the c-MYC pathway could be

  11. A spectroscopic investigation of the interaction between c-MYC DNA and tetrapyridinoporphyrazinatozinc(II).

    Science.gov (United States)

    Hassani, Leila; Fazeli, Zahra; Safaei, Elham; Rastegar, Hossein; Akbari, Minoo

    2014-06-01

    The c-MYC gene plays an important role in the regulation of cell proliferation and growth and it is overexpressed in a wide variety of human cancers. Around 90% of c-MYC transcription is controlled by the nuclease-hypersensitive element III1 (NHE III1), whose 27-nt purine-rich strand has the ability to form a G-quadruplex structure under physiological conditions. Therefore, c-MYC DNA is an attractive target for drug design, especially for cancer chemotherapy. Here, the interaction of water-soluble tetrapyridinoporphyrazinatozinc(II) with 27-nt G-rich strand (G/c-MYC), its equimolar mixture with the complementary sequence (GC/c-MYC) and related C-rich oligonucleotide (C/c-MYC) is investigated. Circular dichroism (CD) measurements of the G-rich 27-mer oligonucleotide in 150 mM KCl, pH 7 demonstrate a spectral signature consistent with parallel G-quadruplex DNA. Furthermore, the CD spectrum of the GC rich oligonucleotide shows characteristics of both duplex and quadruplex structures. Absorption spectroscopy implies that the complex binding of G/c-MYC and GC/c-MYC is a two-step process; in the first step, a very small red shift and hypochromicity and in the second step, a large red shift and hyperchromicity are observed in the Q band. Emission spectra of zinc porphyrazine are quenched upon addition of three types of DNA. According to the results of spectroscopy, it can be concluded the dominant binding mode is probably, outside binding and end stacking.

  12. Enhanced expression of c-myc in hepatocytes promotes initiation and progression of alcoholic liver disease.

    Science.gov (United States)

    Nevzorova, Yulia A; Cubero, Francisco J; Hu, Wei; Hao, Fengjie; Haas, Ute; Ramadori, Pierluigi; Gassler, Nikolaus; Hoss, Mareike; Strnad, Pavel; Zimmermann, Henning W; Tacke, Frank; Trautwein, Christian; Liedtke, Christian

    2016-03-01

    Progression of alcoholic liver disease (ALD) can be influenced by genetic factors, which potentially include specific oncogenes and tumor suppressors. In the present study, we tested the hypothesis that aberrant expression of the proto-oncogene c-myc might exert a crucial role in the development of ALD. Expression of c-myc was measured in biopsies of patients with ALD by quantitative real-time PCR and immunohistochemistry. Mice with transgenic expression of c-myc in hepatocytes (alb-myc(tg)) and wild-type (WT) controls were fed either control or ethanol (EtOH) containing Lieber-DeCarli diet for 4weeks to induce ALD. Hepatic c-myc was strongly upregulated in human patients with advanced ALD and in EtOH-fed WT mice. Transcriptome analysis indicated deregulation of pathways involved in ER-stress, p53 signaling, hepatic fibrosis, cell cycle regulation, ribosomal synthesis and glucose homeostasis in EtOH-fed alb-myc(tg) mice. Transgenic expression of c-myc in hepatocytes with simultaneous EtOH-uptake led to early ballooning degeneration, increased liver collagen deposition and hepatic lipotoxicity, together with excessive CYP2E1-derived reactive oxygen species (ROS) production. Moreover, EtOH-fed alb-myc(tg) mice exhibited substantial changes in mitochondrial morphology associated with energy dysfunction. Pathway analysis revealed that elevated c-myc expression and ethanol uptake synergistically lead to strong AKT activation, Mdm2 phosphorylation and as a consequence to inhibition of p53. Expression of c-myc and EtOH-uptake synergistically accelerate the progression of ALD most likely due to loss of p53-dependent protection. Thus, c-myc is a new potential marker for the early detection of ALD and identification of risk patients. Copyright © 2015 European Association for the Study of the Liver. Published by Elsevier B.V. All rights reserved.

  13. Frequent coamplification and cooperation between C-MYC and PVT1 oncogenes promote malignant pleural mesothelioma.

    Science.gov (United States)

    Riquelme, Erick; Suraokar, Milind B; Rodriguez, Jaime; Mino, Barbara; Lin, Heather Y; Rice, David C; Tsao, Anne; Wistuba, Ignacio I

    2014-07-01

    Malignant pleural mesothelioma (MPM) is a deadly disease with poor prognosis and few treatment options. We characterized and elucidated the roles of C-MYC and PVT1 involved in the pathogenesis of MPM. We used small interfering RNA (siRNA)-mediated knockdown in MPM cell lines to determine the effect of C-MYC and PVT1 abrogation on MPM cells undergoing apoptosis, proliferation, and cisplatin sensitivity. We also characterized the expression of microRNAs spanning the PVT1 region in MPM cell lines. Copy number analysis was measured by quantitative polymerase chain reaction and fluorescence in situ hybridization. Copy number analysis revealed copy number gains (CNGs) in chromosomal region 8q24 in six of 12 MPM cell lines. MicroRNA analysis showed high miR-1204 expression in MSTO-211H cell lines with four copies or more of PVT1. Knockdown by siRNA showed increased PARP-C levels in MSTO-211H transfected with siPVT1 but not in cells transfected with siC-MYC. C-MYC and PVT1 knockdown reduced cell proliferation and increased sensitivity to cisplatin. Analysis of the expression of apoptosis-related genes in the MSTO-211H cell line suggested that C-MYC maintains a balance between proapoptotic and antiapoptotic gene expression, whereas PVT1 and, to a lesser extent, miR-1204 up-regulate proapoptotic genes and down-regulate antiapoptotic genes. Fluorescence in situ hybridization analysis of MPM tumor specimens showed a high frequency of both CNGs (11 of 75) and trisomy (three copies; 11 of 75) for the C-MYC locus. Our results suggest that C-MYC and PVT1 CNG promotes a malignant phenotype of MPM, with C-MYC CNG stimulating cell proliferation and PVT1 both stimulating proliferation and inhibiting apoptosis.

  14. Nuclear Localization and DNA Binding Properties of a Protein Expressed by Human c-myc Oncogene

    Science.gov (United States)

    Persson, Hakan; Leder, Philip

    1984-08-01

    Antisera to the human cellular myc oncogene product were used to identify a human c-myc specific protein with a molecular weight of 65,000. Subcellular fractionation showed that the human c-myc protein is predominantly found in the cell nucleus. The p65 Kc-myc protein binds to double- and single-stranded DNA as measured by a DNA affinity chromatography assay.

  15. Androgen Receptor Promotes Ligand-Independent Prostate Cancer Progression through c-Myc Upregulation

    Science.gov (United States)

    Gao, Lina; Schwartzman, Jacob; Gibbs, Angela; Lisac, Robert; Kleinschmidt, Richard; Wilmot, Beth; Bottomly, Daniel; Coleman, Ilsa; Nelson, Peter; McWeeney, Shannon; Alumkal, Joshi

    2013-01-01

    The androgen receptor (AR) is the principal therapeutic target in prostate cancer. For the past 70 years, androgen deprivation therapy (ADT) has been the major therapeutic focus. However, some patients do not benefit, and those tumors that do initially respond to ADT eventually progress. One recently described mechanism of such an effect is growth and survival-promoting effects of the AR that are exerted independently of the AR ligands, testosterone and dihydrotestosterone. However, specific ligand-independent AR target genes that account for this effect were not well characterized. We show here that c-Myc, which is a key mediator of ligand-independent prostate cancer growth, is a key ligand-independent AR target gene. Using microarray analysis, we found that c-Myc and AR expression levels strongly correlated with each other in tumors from patients with castration-resistant prostate cancer (CRPC) progressing despite ADT. We confirmed that AR directly regulates c-Myc transcription in a ligand-independent manner, that AR and c-Myc suppression reduces ligand-independent prostate cancer cell growth, and that ectopic expression of c-Myc attenuates the anti-growth effects of AR suppression. Importantly, treatment with the bromodomain inhibitor JQ1 suppressed c-Myc function and suppressed ligand-independent prostate cancer cell survival. Our results define a new link between two critical proteins in prostate cancer – AR and c-Myc – and demonstrate the potential of AR and c-Myc-directed therapies to improve prostate cancer control. PMID:23704919

  16. Lack of Cyclin-Dependent Kinase 4 Inhibits c-myc Tumorigenic Activities in Epithelial Tissues

    OpenAIRE

    Miliani de Marval, Paula L; Macias, Everardo; Rounbehler, Robert; Sicinski, Piotr; Kiyokawa, Hiroaki; Johnson, David G.; Conti, Claudio J; Rodriguez-Puebla, Marcelo L.

    2004-01-01

    The proto-oncogene c-myc encodes a transcription factor that is implicated in the regulation of cellular proliferation, differentiation, and apoptosis and that has also been found to be deregulated in several forms of human and experimental tumors. We have shown that forced expression of c-myc in epithelial tissues of transgenic mice (K5-Myc) resulted in keratinocyte hyperproliferation and the development of spontaneous tumors in the skin and oral cavity. Although a number of genes involved i...

  17. Apigenin induces c-Myc-mediated apoptosis in FRO anaplastic thyroid carcinoma cells.

    Science.gov (United States)

    Kim, Si Hyoung; Kang, Jun Goo; Kim, Chul Sik; Ihm, Sung-Hee; Choi, Moon Gi; Yoo, Hyung Joon; Lee, Seong Jin

    2013-04-30

    Apigenin promotes apoptosis in cancer cells. We studied the effect of apigenin on cell survival and c-Myc expression in FRO anaplastic thyroid carcinoma (ATC) cells. Apigenin caused apoptosis via the elevation of c-Myc levels in conjunction with the phosphorylation of p38 and p53. In the c-Myc siRNA-transfected and apigenin-treated cells, compared with the apigenin-treated control cells, apoptosis and phosphorylation of p38 and p53 were ameliorated. In the presence of apigenin, diminution of p38 and p53 did not affect cell survival although apigenin activated the phosphorylation of p38 and p53 via increased c-Myc levels. In conclusion, our results indicate that apigenin induces apoptosis mediated via c-Myc with concomitant phosphorylation of p53 and p38 in FRO ATC cells. These findings suggest that augmented c-Myc acts as a core regulator and is necessary for apigenin-induced apoptosis in FRO ATC cells. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

  18. Transcript Regulation of Human Telomerase Reverse Transcriptase by c-myc and mad1

    Institute of Scientific and Technical Information of China (English)

    Lin ZOU; Peng-Hui ZHANG; Chun-Li LUO; Zhi-Guang TU

    2005-01-01

    Telomerase activity is highly positive correlated to most malignant neoplasms. Human telomerase reverse transcriptase (hTERT) is the rate-limiting factor of telomerase activity. Recent studies have shown that the expression of hTERT is mainly determined by its transcript regulation. Among the transcript regulation factors of hTERT, c-myc and mad1 are well known. Here, we constructed c-myc and mad1 eukaryotic expression vectors, then co-transfected them with the wild-type (Tw) or mutant hTERT promoter (Td)luciferase reporter plasmid, which were double-mutated in the E-box sequences from CACGTG to CACCTG of Tw. The change of luciferase activity in different cells was detected. The results showed that Tw was obviously activated in T24 and EJ bladder cancer cells, but not in normal fibrocytes. c-myc and mad1 had positive and negative effects respectively on the Tw transcript in a dose-dependent manner, while the roles of c-myc and mad1 in regulating the Td transcript were reversed. c-myc combined with mad1 can downregulate Tw but not Td. These observations indicate that c-myc and mad1 can regulate the hTERT transcript in a different manner in hTERT positive cells, but not in normal cells. This may provide an insight into some telomerase-related carcinogenesis mechanisms.

  19. ELL targets c-Myc for proteasomal degradation and suppresses tumour growth

    Science.gov (United States)

    Chen, Yu; Zhou, Chi; Ji, Wei; Mei, Zhichao; Hu, Bo; Zhang, Wei; Zhang, Dawei; Wang, Jing; Liu, Xing; Ouyang, Gang; Zhou, Jiangang; Xiao, Wuhan

    2016-01-01

    Increasing evidence supports that ELL (eleven–nineteen lysine-rich leukaemia) is a key regulator of transcriptional elongation, but the physiological function of Ell in mammals remains elusive. Here we show that ELL functions as an E3 ubiquitin ligase and targets c-Myc for proteasomal degradation. In addition, we identify that UbcH8 serves as a ubiquitin-conjugating enzyme in this pathway. Cysteine 595 of ELL is an active site of the enzyme; its mutation to alanine (C595A) renders the protein unable to promote the ubiquitination and degradation of c-Myc. ELL-mediated c-Myc degradation inhibits c-Myc-dependent transcriptional activity and cell proliferation, and also suppresses c-Myc-dependent xenograft tumour growth. In contrast, the ELL(C595A) mutant not only loses the ability to inhibit cell proliferation and xenograft tumour growth, but also promotes tumour metastasis. Thus, our work reveals a previously unrecognized function for ELL as an E3 ubiquitin ligase for c-Myc and a potential tumour suppressor. PMID:27009366

  20. c-MYC is a radiosensitive locus in human breast cells.

    Science.gov (United States)

    Wade, M A; Sunter, N J; Fordham, S E; Long, A; Masic, D; Russell, L J; Harrison, C J; Rand, V; Elstob, C; Bown, N; Rowe, D; Lowe, C; Cuthbert, G; Bennett, S; Crosier, S; Bacon, C M; Onel, K; Scott, K; Scott, D; Travis, L B; May, F E B; Allan, J M

    2015-09-17

    Ionising radiation is a potent human carcinogen. Epidemiological studies have shown that adolescent and young women are at increased risk of developing breast cancer following exposure to ionising radiation compared with older women, and that risk is dose-dependent. Although it is well understood which individuals are at risk of radiation-induced breast carcinogenesis, the molecular genetic mechanisms that underlie cell transformation are less clear. To identify genetic alterations potentially responsible for driving radiogenic breast transformation, we exposed the human breast epithelial cell line MCF-10A to fractionated doses of X-rays and examined the copy number and cytogenetic alterations. We identified numerous alterations of c-MYC that included high-level focal amplification associated with increased protein expression. c-MYC amplification was also observed in primary human mammary epithelial cells following exposure to radiation. We also demonstrate that the frequency and magnitude of c-MYC amplification and c-MYC protein expression is significantly higher in breast cancer with antecedent radiation exposure compared with breast cancer without a radiation aetiology. Our data also demonstrate extensive intratumor heterogeneity with respect to c-MYC copy number in radiogenic breast cancer, suggesting continuous evolution at this locus during disease development and progression. Taken together, these data identify c-MYC as a radiosensitive locus, implicating this oncogenic transcription factor in the aetiology of radiogenic breast cancer.

  1. The c-Myc Transactivation Domain Is a Direct Modulator of Apoptotic versus Proliferative Signals

    Science.gov (United States)

    Chang, David W.; Claassen, Gisela F.; Hann, Stephen R.; Cole, Michael D.

    2000-01-01

    We have assayed the oncogenic, proliferative, and apoptotic activities of the frequent mutations that occur in the c-myc gene in Burkitt's lymphomas. Some alleles have a modest (50 to 60%) increase in transforming activity; however, the most frequent Burkitt's lymphoma allele (T58I) had an unexpected substantial decrease in transforming activity (85%). All alleles restored the proliferation function of c-Myc in cells that grow slowly due to a c-myc knockout. There was discordance for some alleles between apoptotic and oncogenic activities, but only the T58A allele had elevated transforming activity with a concomitant reduced apoptotic potential. We discovered a novel missense mutation, MycS71F, that had a very low apoptotic activity compared to wild-type Myc, yet this mutation has never been found in lymphomas, suggesting that there is no strong selection for antiapoptotic c-Myc alleles. MycS71F also induced very low levels of cytochrome c release from mitochondria, suggesting a mechanism of action for this mutation. Phosphopeptide mapping provided a biochemical basis for the dramatically different biological activities of the transformation-defective T58I and transformation-enhanced T58A c-Myc alleles. Furthermore, the antiapoptotic survival factor insulin-like growth factor 1 was found to suppress phosphorylation of T58, suggesting that the c-Myc transactivation domain is a direct target of survival signals. PMID:10825194

  2. Differential regulation of the c-Myc/Lin28 axis discriminates subclasses of rearranged MLL leukemia

    Science.gov (United States)

    Chen, Lili; Sun, Yuqing; Wang, Jingya; Jiang, Hui; Muntean, Andrew G.

    2016-01-01

    MLL rearrangements occur in myeloid and lymphoid leukemias and are generally associated with a poor prognosis, however this varies depending on the fusion partner. We modeled acute myeloid leukemia (AML) in mice using various MLL fusion proteins (MLL-FPs) and observed significantly different survival outcomes. To better understand the differences between these leukemias, we examined the genome wide expression profiles of leukemic cells transformed with different MLL-FPs. RNA-sequencing and pathway analysis identified the c-Myc transcriptional program as one of the top distinguishing features. c-Myc protein levels were highly correlative with AML disease latency in mice. Functionally, overexpression of c-Myc resulted in a more aggressive proliferation rate in MLL-FP cell lines. While all MLL-FP transformed cells displayed sensitivity to BET inhibitors, high c-Myc expressing cells showed greater resistance to Brd4 inhibition. The Myc target Lin28B was also differentially expressed in MLL-FP cell lines in agreement with c-Myc expression. Examination of Lin28B miRNAs targets revealed that let-7g was significantly increased in leukemic cells associated with the longest disease latency and forced let-7g expression induced differentiation of leukemic blasts. Thus, differential regulation of the c-Myc/Lin28/let-7g program by different MLL-FPs is functionally related to disease latency and BET inhibitor resistance in MLL leukemias. PMID:27007052

  3. Quadruplex forming promoter region of c-myc oncogene as a potential target for a telomerase inhibitory plant alkaloid, chelerythrine.

    Science.gov (United States)

    Ghosh, Saptaparni; Dasgupta, Dipak

    2015-03-27

    Guanine rich sequences present in the promoter region of oncogenes could fold into G-quadruplexes and modulate transcription. Equilibrium between folding and unfolding of the quadruplexes in these regions play important role in disease processes. We have studied the effect of a putative anticancer agent chelerythrine on G-rich NHE III1 present in the promoter region of c-myc oncogene. We have demonstrated the ability of chelerythrine, a telomerase inhibitor, to block the hybridization of Pu27 with its complementary strand via folding it into a quadruplex structure. Calorimetry shows that the association of Pu27 with chelerythrine is primarily enthalpy driven with high binding affinity (∼10(5) M(-1)). The association does not lead to any major structural perturbation of Pu27. The resulting 2:1 complex has enhanced stability as compared to free Pu27. Another notable feature is that the presence of molecular crowding agent like ficoll 70 does not change the mode of recognition though the binding affinity decreases. We suggest that the anticancer activity of chelerythrine could be ascribed to its ability to stabilize the quadruplex structure in the c-myc promoter region thereby downregulating its transcription. Copyright © 2015 Elsevier Inc. All rights reserved.

  4. NM23-H2 may play an indirect role in transcriptional activation of c-myc gene expression but does not cleave the nuclease hypersensitive element III[subscript 1

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    Dexheimer, Thomas S.; Carey, Steven S.; Zuohe, Song; Gokhale, Vijay M.; Hu, Xiaohui; Murata, Lauren B.; Maes, Estelle M.; Weichsel, Andrzej; Sun, Daekyu; Meuillet, Emmanuelle J.; Montfort, William R.; Hurley, Laurence H. (Ariz)

    2009-05-13

    The formation of G-quadruplex structures within the nuclease hypersensitive element (NHE) III{sub 1} region of the c-myc promoter and the ability of these structures to repress c-myc transcription have been well established. However, just how these extremely stable DNA secondary structures are transformed to activate c-myc transcription is still unknown. NM23-H2/nucleoside diphosphate kinase B has been recognized as an activator of c-myc transcription via interactions with the NHE III{sub 1} region of the c-myc gene promoter. Through the use of RNA interference, we confirmed the transcriptional regulatory role of NM23-H2. In addition, we find that further purification of NM23-H2 results in loss of the previously identified DNA strand cleavage activity, but retention of its DNA binding activity. NM23-H2 binds to both single-stranded guanine- and cytosine-rich strands of the c-myc NHE III{sub 1} and, to a lesser extent, to a random single-stranded DNA template. However, it does not bind to or cleave the NHE III{sub 1} in duplex form. Significantly, potassium ions and compounds that stabilize the G-quadruplex and i-motif structures have an inhibitory effect on NM23-H2 DNA-binding activity. Mutation of Arg{sup 88} to Ala{sup 88} (R88A) reduced both DNA and nucleotide binding but had minimal effect on the NM23-H2 crystal structure. On the basis of these data and molecular modeling studies, we have proposed a stepwise trapping-out of the NHE III{sub 1} region in a single-stranded form, thus allowing single-stranded transcription factors to bind and activate c-myc transcription. Furthermore, this model provides a rationale for how the stabilization of the G-quadruplex or i-motif structures formed within the c-myc gene promoter region can inhibit NM23-H2 from activating c-myc gene expression.

  5. Control of gene expression during T cell activation: alternate regulation of mRNA transcription and mRNA stability

    Directory of Open Access Journals (Sweden)

    Gorospe Myriam

    2005-05-01

    Full Text Available Abstract Background Microarray technology has become highly valuable for identifying complex global changes in gene expression patterns. The effective correlation of observed changes in gene expression with shared transcription regulatory elements remains difficult to demonstrate convincingly. One reason for this difficulty may result from the intricate convergence of both transcriptional and mRNA turnover events which, together, directly influence steady-state mRNA levels. Results In order to investigate the relative contribution of gene transcription and changes in mRNA stability regulation to standard analyses of gene expression, we used two distinct microarray methods which individually measure nuclear gene transcription and changes in polyA mRNA gene expression. Gene expression profiles were obtained from both polyA mRNA (whole-cell and nuclear run-on (newly transcribed RNA across a time course of one hour following the activation of human Jurkat T cells with PMA plus ionomycin. Comparative analysis revealed that regulation of mRNA stability may account for as much as 50% of all measurements of changes in polyA mRNA in this system, as inferred by the absence of any corresponding regulation of nuclear gene transcription activity for these groups of genes. Genes which displayed dramatic elevations in both mRNA and nuclear run-on RNA were shown to be inhibited by Actinomycin D (ActD pre-treatment of cells while large numbers of genes regulated only through altered mRNA turnover (both up and down were ActD-resistant. Consistent patterns across the time course were observed for both transcribed and stability-regulated genes. Conclusion We propose that regulation of mRNA stability contributes significantly to the observed changes in gene expression in response to external stimuli, as measured by high throughput systems.

  6. THE EFFECTS OF RETINOIC ACID ON EXPRESSION OF C-MYC, C-FOS IN LEUKEMIC PROMYELOCYTES

    Institute of Scientific and Technical Information of China (English)

    邵国英; 徐荣婷; 孙关林; 欧阳仁荣; 应大明

    1992-01-01

    The expression of c-myc, c-fos of leukemic promyelocytes (HL-60 and acute promyelocytic leukemia cells) from 18 acute promyelocytic leukemia (APL) patients treated with all-trans retinoic acid (RA) in vitro was studied. There was no expression of c-fos in HL-60 cells and APL cells from 17 patients. But in one case, a slight expression of c-fos in leukemic cells was observed, and the alteration of expression level was found during the treatment of the cells with RA in vitro. The expression of c-myc in HL-60 cells induced by RA was altered, decrease in the early, increase in the middle, and decline in the later stage were found. The c-myc expression in leukemic cells of eighteen APL patients was variable. There was c-myc expression in eleven APL cells, but no expression in the others. The APL cells with c-myc expression were treated with RA in vitro to observe the kinetic changes of c-myc RNA level. The results showed that the expression of c-myc was gradually decreased except in few cases. Using in situ hybridization technique for detecting the alteration of c-myc expression in leukemic cells of two APL patients. the high level of c-myc before RA treatment and low level of c-myc expression after obtaining complete remission induced by RA were found. The possibility of different proto-oncogenes implicated differentiation was discussed.

  7. The regulatory role of c-MYC on HDAC2 and PcG expression in human multipotent stem cells

    Science.gov (United States)

    Bhandari, Dilli Ram; Seo, Kwang-Won; Jung, Ji-Won; Kim, Hyung-Sik; Yang, Se-Ran; Kang, Kyung-Sun

    2011-01-01

    Abstract Myelocytomatosis oncogene (c-MYC) is a well-known nuclear oncoprotein having multiple functions in cell proliferation, apoptosis and cellular transformation. Chromosomal modification is also important to the differentiation and growth of stem cells. Histone deacethylase (HDAC) and polycomb group (PcG) family genes are well-known chromosomal modification genes. The aim of this study was to elucidate the role of c-MYC in the expression of chromosomal modification via the HDAC family genes in human mesenchymal stem cells (hMSCs). To achieve this goal, c-MYC expression was modified by gene knockdown and overexpression via lentivirus vector. Using the modified c-MYC expression, our study was focused on cell proliferation, differentiation and cell cycle. Furthermore, the relationship of c-MYC with HDAC2 and PcG genes was also examined. The cell proliferation and differentiation were checked and shown to be dramatically decreased in c-MYC knocked-down human umbilical cord blood-derived MSCs, whereas they were increased in c-MYC overexpressing cells. Similarly, RT-PCR and Western blotting results revealed that HDAC2 expression was decreased in c-MYC knocked-down and increased in c-MYC overexpressing hMSCs. Database indicates presence of c-MYC binding motif in HDAC2 promoter region, which was confirmed by chromatin immunoprecipitation assay. The influence of c-MYC and HDAC2 on PcG expression was confirmed. This might indicate the regulatory role of c-MYC over HDAC2 and PcG genes. c-MYCs’ regulatory role over HDAC2 was also confirmed in human adipose tissue-derived MSCs and bone-marrow derived MSCs. From this finding, it can be concluded that c-MYC plays a vital role in cell proliferation and differentiation via chromosomal modification. PMID:20716118

  8. A long noncoding RNA connects c-Myc to tumor metabolism

    Science.gov (United States)

    Hung, Chiu-Lien; Wang, Ling-Yu; Yu, Yen-Ling; Chen, Hong-Wu; Srivastava, Shiv; Petrovics, Gyorgy; Kung, Hsing-Jien

    2014-01-01

    Long noncoding RNAs (lncRNAs) have been implicated in a variety of physiological and pathological processes, including cancer. In prostate cancer, prostate cancer gene expression marker 1 (PCGEM1) is an androgen-induced prostate-specific lncRNA whose overexpression is highly associated with prostate tumors. PCGEM1’s tumorigenic potential has been recently shown to be in part due to its ability to activate androgen receptor (AR). Here, we report a novel function of PCGEM1 that provides growth advantages for cancer cells by regulating tumor metabolism via c-Myc activation. PCGEM1 promotes glucose uptake for aerobic glycolysis, coupling with the pentose phosphate shunt to facilitate biosynthesis of nucleotide and lipid, and generates NADPH for redox homeostasis. We show that PCGEM1 regulates metabolism at a transcriptional level that affects multiple metabolic pathways, including glucose and glutamine metabolism, the pentose phosphate pathway, nucleotide and fatty acid biosynthesis, and the tricarboxylic acid cycle. The PCGEM1-mediated gene regulation takes place in part through AR activation, but predominantly through c-Myc activation, regardless of hormone or AR status. Significantly, PCGEM1 binds directly to target promoters, physically interacts with c-Myc, promotes chromatin recruitment of c-Myc, and enhances its transactivation activity. We also identified a c-Myc binding domain on PCGEM1 that contributes to the PCGEM1-dependent c-Myc activation and target induction. Together, our data uncover PCGEM1 as a key transcriptional regulator of central metabolic pathways in prostate cancer cells. By being a coactivator for both c-Myc and AR, PCGEM1 reprograms the androgen network and the central metabolism in a tumor-specific way, making it a promising target for therapeutic intervention. PMID:25512540

  9. Knocking-down of CREPT prohibits the progression of oral squamous cell carcinoma and suppresses cyclin D1 and c-Myc expression.

    Science.gov (United States)

    Ma, Juntao; Ren, Yipeng; Zhang, Lei; Kong, Xiangpan; Wang, Tong; Shi, Yueyi; Bu, Rongfa

    2017-01-01

    As a regulator essential for many cell cycle-related proteins, the robust expression of Cell cycle-Related and Expression-elevated Protein in Tumor (CREPT) implicates a poor diagnosis of endoderm and mesoderm-derived tumors. Whether CREPT plays the same role in the tumorigenesis derived from ectodermal tissues remains elusive. To explore the role of CREPT in ectoderm-derived tumors, cells from 7oral squamous cell carcinoma (OSCC) lines and 84clinical OSCC samples were exploited in this study. Quantitative PCR, Western blot assay and immunohistochemistry were applied in the evaluation of CREPT, cyclin D1 and c-Myc expression. Knocking-down of CREPT was performed by lentivirus delivering specific shRNA of CREPT. The effects of CREPT on OSCC were examined by cell proliferation, colony formation, apoptosis, cell migration and xenograft implantation experiments. Compared with human normal oral keratinocytes, OSCC cell lines showed a significantly elevated expression of CREPT in both mRNA and protein levels. Consistently, samples from OSCC patients also exhibited a noticeably stronger CREPT expression than the noncancerous samples. In contrast, knocking down of CREPT in OSCC cell lines significantly reduced proliferation, colony formation and migration as well as the expression of cyclin D1 and c-Myc, but promoted apoptosis. Statistical analysis also suggested that CREPT expression was significantly correlated with the T and N classification of OSCC. Furthermore, CAL27 mouse xenograft model confirmed that down-regulation of CREPT prohibited cyclin D1 and c-Myc expression, through which decreased the in vivo tumor growth, but increased the survival ratio of hosts. In OSCC cell lines, up-regulated CREPT expression enhanced cell proliferation, migration and cell cycle as well as promoted cyclin D1 and c-Myc expression as it did in endoderm and mesoderm-origin tumors. Our study strongly suggests that CREPT could be used as a marker for the OSCC prognosis and might work as a

  10. Equol, an Isoflavone Metabolite, Regulates Cancer Cell Viability and Protein Synthesis Initiation via c-Myc and eIF4G*

    Science.gov (United States)

    de la Parra, Columba; Borrero-Garcia, Luis D.; Cruz-Collazo, Ailed; Schneider, Robert J.; Dharmawardhane, Suranganie

    2015-01-01

    Epidemiological studies implicate dietary soy isoflavones as breast cancer preventives, especially due to their anti-estrogenic properties. However, soy isoflavones may also have a role in promoting breast cancer, which has yet to be clarified. We previously reported that equol, a metabolite of the soy isoflavone daidzein, may advance breast cancer potential via up-regulation of the eukaryotic initiation factor 4GI (eIF4GI). In estrogen receptor negative (ER−) metastatic breast cancer cells, equol induced elevated levels of eIF4G, which were associated with increased cell viability and the selective translation of mRNAs that use non-canonical means of initiation, including internal ribosome entry site (IRES), ribosome shunting, and eIF4G enhancers. These mRNAs typically code for oncogenic, survival, and cell stress molecules. Among those mRNAs translationally increased by equol was the oncogene and eIF4G enhancer, c-Myc. Here we report that siRNA-mediated knockdown of c-Myc abrogates the increase in cancer cell viability and mammosphere formation by equol, and results in a significant down-regulation of eIF4GI (the major eIF4G isoform), as well as reduces levels of some, but not all, proteins encoded by mRNAs that are translationally stimulated by equol treatment. Knockdown of eIF4GI also markedly reduces an equol-mediated increase in IRES-dependent mRNA translation and the expression of specific oncogenic proteins. However, eIF4GI knockdown did not reciprocally affect c-Myc levels or cell viability. This study therefore implicates c-Myc as a potential regulator of the cancer-promoting effects of equol via up-regulation of eIF4GI and selective initiation of translation on mRNAs that utilize non-canonical initiation, including certain oncogenes. PMID:25593313

  11. Oxidative damage, pro-inflammatory cytokines, TGF-α and c-myc in chronic HCV-related hepatitis and cirrhosis

    Institute of Scientific and Technical Information of China (English)

    Fabio Farinati; Romilda Cardin; Marina Bortolami; Maria Guido; Massimo Rugge

    2006-01-01

    AIM: To assess whether a correlation exists between oxidative DNA damage occurring in chronic HCV-relatecl hepatitis and expression levels of pro-inflammatory cytokines, TGF-α and c-myc.METHODS: The series included 37 patients with chronic active HCV-related hepatitis and 11 with HCV-related compensated cirrhosis. Eight-hydroxydeoxyguanosine in liver biopsies was quantified using an electrochemical detector. The mRNA expression of TNF-α, IL-1β, TGF-αand c-myc in liver specimens was detected by semiquantitative comparative RT-PCR.RESULTS: TNF-α levels were significantly higher in hepatitis patients than in cirrhosis patients (P=0.05).IL-1β was higher in cirrhosis patients (P=0.05). A significant correlation was found between TNF-α and staging (P=0.05) and between IL-1β levels and grading (P= 0.04). c-myc showed a significantly higher expression in cirrhosis patients (P=0.001). Eight-hydroxydeoxyguanosine levels were significantly higher in cirrhosis patients (P=0.05) and in HCV genotype 1. (P=0.03).Considering all patients, 8-hydroxydeoxyguanosine levels were found to be correlated with genotype (P=0.04)and grading (P=0.007). Also multiple logistic regression analysis demonstrated a significant correlation among the number of DNA adducts, TNF-α expression and HCV genotype (P= 0.02).CONCLUSION: In chronic HCV-related liver damage, oxidative DNA damage correlates with HCV genotype, grading and TNF-α levels. As HCV-related liver damage progresses, TNF-α levels drop while IL-1β and c-myc levels increase, which may be relevant to liver carcinogenesis.

  12. A regulatory loop involving miR-22, Sp1, and c-Myc modulates CD147 expression in breast cancer invasion and metastasis.

    Science.gov (United States)

    Kong, Ling-Min; Liao, Cheng-Gong; Zhang, Yang; Xu, Jing; Li, Yu; Huang, Wan; Zhang, Yi; Bian, Huijie; Chen, Zhi-Nan

    2014-07-15

    Breast cancer is the most common cancer in women for which the metastatic process is still poorly understood. CD147 is upregulated in breast cancer and has been associated with tumor progression, but little is known about its regulatory mechanisms. In this study, we demonstrated that CD147 was overexpressed in breast cancer tissues and cell lines, and the high expression correlated with tumor invasion and metastasis. We also found that the transcription factors Sp1 and c-Myc could bind to the CD147 promoter and enhance its expression. The CD147 mRNA has a 748-bp 3'-untranslated region (UTR) with many miRNA target sites, suggesting possible regulation by miRNAs. We discovered that miR-22 repressed CD147 expression by directly targeting the CD147 3'UTR. We also determined that miR-22 could indirectly participate in CD147 modulation by downregulating Sp1 expression. miR-22 could form an autoregulatory loop with Sp1, which repressed miR-22 transcription by binding to the miR-22 promoter. Together with the c-Myc-mediated inhibition of miR-22 expression, our investigation identified a miR-22/Sp1/c-Myc network that regulates CD147 gene transcription. In addition, miR-22 overexpression suppressed breast cancer cell invasion, metastasis, and proliferation by targeting CD147 in vitro and in vivo. Furthermore, we found that miR-22 was significantly downregulated in breast cancer tissues and that its expression was inversely correlated with the tumor-node-metastasis stage and lymphatic metastasis in patients. Our study provides the first evidence that an miR-22/Sp1/c-Myc network regulates CD147 upregulation in breast cancer and that miR-22 represses breast cancer invasive and metastatic capacities.

  13. The impact of C-MYC gene expression on gastric cancer cell

    Science.gov (United States)

    Hou, Yanhong; Ashktorab, Hassan; Gao, Liucun; Xu, Yanjie; Wu, Kai; Zhai, Junshan; Zhang, Lei

    2012-01-01

    The upregulation or mutation of C-MYC has been observed in gastric, colon, breast, and lung tumors and in Burkitt’s lymphoma. However, little is known about the role C-MYC plays in gastric adenocarcinoma. In the present study, we intended to investigate the influence of C-MYC on the growth, proliferation, apoptosis, invasion, and cell cycle of the gastric cancer cell line SGC7901 and the gastric cell line HFE145. C-MYC cDNA was subcloned into a constitutive vector PCDNA3.1 followed by transfection in normal gastric cell line HFE145 by using liposome. Then stable transfectants were selected and appraised. Specific inhibition of C-MYC was achieved using a vector-based siRNA system which was transfected in gastric cancer cell line SGC7901. The apoptosis and cell cycles of these clones were analyzed by using flow cytometric assay. The growth and proliferation were analyzed by cell growth curves and colony-forming assay, respectively. The invasion of these clones was analyzed by using cell migration assay. The C-MYC stable expression clones (HFE-Myc) and C-MYC RNAi cells (SGC-MR) were detected and compared with their control groups, respectively. HFE-Myc grew faster than HFE145 and HFE-PC (HFE145 transfected with PCDNA3.1 vector). SGC-MR1, 2 grew slower than SGC7901 and SGC-MS1, 2 (SGC7901 transfected with scrambled control duplexes). The cell counts of HFE-Myc in the third, fourth, fifth, sixth, and seventh days were significantly more than those of control groups (P 0.05). In conclusion, C-MYC can promote the growth and proliferation of normal gastric cells, and knockdown of C-MYC can restrain the growth and proliferation of gastric cancer cells. It can induce cell apoptosis and help tumor cell maintain malignant phenotype. But it can have not a detectable influence on the ability of invasion of gastric cancer cells. PMID:20737197

  14. Cytoplasmic expression of C-MYC protein is associated with risk stratification of mantle cell lymphoma

    Directory of Open Access Journals (Sweden)

    Yi Gong

    2017-06-01

    Full Text Available Aim To investigate the association of C-MYC protein expression and risk stratification in mantle cell lymphoma (MCL, and to evaluate the utility of C-MYC protein as a prognostic biomarker in clinical practice. Methods We conducted immunohistochemical staining of C-MYC, Programmed cell death ligand 1 (PD-L1, CD8, Ki-67, p53 and SRY (sex determining region Y -11 (SOX11 to investigate their expression in 64 patients with MCL. The staining results and other clinical data were evaluated for their roles in risk stratification of MCL cases using ANOVA, Chi-square, and Spearman’s Rank correlation coefficient analysis. Results Immunohistochemical staining in our study indicated that SOX11, Ki-67 and p53 presented nuclear positivity of tumor cells, CD8 showed membrane positivity in infiltrating T lymphocytes while PD-L1 showed membrane and cytoplasmic positivity mainly in macrophage cells and little in tumor cells. We observed positive staining of C-MYC either in the nucleus or cytoplasm or in both subcellular locations. There were significant differences in cytoplasmic C-MYC expression, Ki-67 proliferative index of tumor cells, and CD8 positive tumor infiltrating lymphocytes (CD8+TIL among three risk groups (P = 0.000, P = 0.037 and P=0.020, respectively. However, no significant differences existed in the expression of nuclear C-MYC, SOX11, p53, and PD-L1 in MCL patients with low-, intermediate-, and high risks. In addition, patient age and serum LDH level were also significantly different among 3 groups of patients (P = 0.006 and P = 0.000, respectively. Spearman’s rank correlation coefficient analysis indicated that cytoplasmic C-MYC expression, Ki-67 index, age, WBC, as well as LDH level had significantly positive correlations with risk stratification (P = 0.000, 0.015, 0.000, 0.029 and 0.000, respectively, while CD8+TIL in tumor microenvironment negatively correlated with risk stratification of patients (P = 0.006. Patients with

  15. c-MYC—Making Liver Sick: Role of c-MYC in Hepatic Cell Function, Homeostasis and Disease

    Science.gov (United States)

    Zheng, Kang; Cubero, Francisco Javier; Nevzorova, Yulia A.

    2017-01-01

    Over 35 years ago, c-MYC, a highly pleiotropic transcription factor that regulates hepatic cell function, was identified. In recent years, a considerable increment in the number of publications has significantly shifted the way that the c-MYC function is perceived. Overexpression of c-MYC alters a wide range of roles including cell proliferation, growth, metabolism, DNA replication, cell cycle progression, cell adhesion and differentiation. The purpose of this review is to broaden the understanding of the general functions of c-MYC, to focus on c-MYC-driven pathogenesis in the liver, explain its mode of action under basal conditions and during disease, and discuss efforts to target c-MYC as a plausible therapy for liver disease. PMID:28422055

  16. c-Myc regulates cell size and ploidy but is not essential for postnatal proliferation in liver

    Science.gov (United States)

    Baena, Esther; Gandarillas, Alberto; Vallespinós, Mireia; Zanet, Jennifer; Bachs, Oriol; Redondo, Clara; Fabregat, Isabel; Martinez-A., Carlos; Moreno de Alborán, Ignacio

    2005-05-01

    The c-Myc protein is a transcription factor implicated in the regulation of multiple biological processes, including cell proliferation, cell growth, and apoptosis. In vivo overexpression of c-myc is linked to tumor development in a number of mouse models. Here, we show that perinatal inactivation of c-Myc in liver causes disorganized organ architecture, decreased hepatocyte size, and cell ploidy. Furthermore, c-Myc appears to have distinct roles in proliferation in liver. Thus, postnatal hepatocyte proliferation does not require c-Myc, whereas it is necessary for liver regeneration in adult mice. These results show novel physiological functions of c-myc in liver development and hepatocyte proliferation and growth.

  17. VARIATION AND SIGNIFICANCE OF C-MYC PROTEIN IN RAT CARDIAC VOLUME-OVERLOAD HYP ERTROPHY

    Institute of Scientific and Technical Information of China (English)

    刘华胜; 马爱群; 王一理; 刘勇; 李恒力; 田红燕

    2002-01-01

    Objective To investigate the change of c-myc protein, which was chosen as the response indicator to volume-overload. Methods The time and spatial course of c-myc protein expressi on on the model of rat cardiac volume-overload hyper trophy was examined by immunohistochemical study. Results The immunohistochemica l study indicated the expression of c-myc protein was increased obviously at 4 -6 hours (62.73%) than that of control (45.41%, P<0.01) after the volume-o verload, then decreased gradually along with development of volume-overload hyp ertrophy and was decreased extremely at 5 months(r=-0.514,P<0.01).Conclusion There are disorders in the signal transduction pathways governing the hypertrophic respon se of cardiomyocytes in hypertrophic myocardium. C-myc gene and the product of it may be only the promoter gene of myocardial hypertrophy. Once switching on, c-myc gene and the product of it do not act anymore;While it may be that c-my c gene and the product of it increased following with myocardial hypertrophy, an d have not direct relation to the occurrence and development of myocardial hyper trophy.

  18. Signal transducer and activator of transcription STAT5 is recruited to c-Myc super-enhancer.

    Science.gov (United States)

    Pinz, Sophia; Unser, Samy; Rascle, Anne

    2016-04-14

    c-Myc has been proposed as a putative target gene of signal transducer and activator of transcription 5 (STAT5). No functional STAT5 binding site has been identified so far within the c-Myc gene locus, therefore a direct transcriptional regulation by STAT5 remains uncertain. c-Myc super-enhancer, located 1.7 Mb downstream of the c-Myc gene locus, was recently reported as essential for the regulation of c-Myc gene expression by hematopoietic transcription factors and bromodomain and extra-terminal (BET) proteins and for leukemia maintenance. c-Myc super-enhancer is composed of five regulatory regions (E1-E5) which recruit transcription and chromatin-associated factors, mediating chromatin looping and interaction with the c-Myc promoter. We now show that STAT5 strongly binds to c-Myc super-enhancer regions E3 and E4, both in normal and transformed Ba/F3 cells. We also found that the BET protein bromodomain-containing protein 2 (BRD2), a co-factor of STAT5, co-localizes with STAT5 at E3/E4 in Ba/F3 cells transformed by the constitutively active STAT5-1*6 mutant, but not in non-transformed Ba/F3 cells. BRD2 binding at E3/E4 coincides with c-Myc transcriptional activation and is lost upon treatment with deacetylase and BET inhibitors, both of which inhibit STAT5 transcriptional activity and c-Myc gene expression. Our data suggest that constitutive STAT5 binding to c-Myc super-enhancer might contribute to BRD2 maintenance and thus allow sustained expression of c-Myc in Ba/F3 cells transformed by STAT5-1*6.

  19. Endogenous c-Myc is essential for p53-induced apoptosis in response to DNA damage in vivo.

    Science.gov (United States)

    Phesse, T J; Myant, K B; Cole, A M; Ridgway, R A; Pearson, H; Muncan, V; van den Brink, G R; Vousden, K H; Sears, R; Vassilev, L T; Clarke, A R; Sansom, O J

    2014-06-01

    Recent studies have suggested that C-MYC may be an excellent therapeutic cancer target and a number of new agents targeting C-MYC are in preclinical development. Given most therapeutic regimes would combine C-MYC inhibition with genotoxic damage, it is important to assess the importance of C-MYC function for DNA damage signalling in vivo. In this study, we have conditionally deleted the c-Myc gene in the adult murine intestine and investigated the apoptotic response of intestinal enterocytes to DNA damage. Remarkably, c-Myc deletion completely abrogated the immediate wave of apoptosis following both ionizing irradiation and cisplatin treatment, recapitulating the phenotype of p53 deficiency in the intestine. Consistent with this, c-Myc-deficient intestinal enterocytes did not upregulate p53. Mechanistically, this was linked to an upregulation of the E3 Ubiquitin ligase Mdm2, which targets p53 for degradation in c-Myc-deficient intestinal enterocytes. Further, low level overexpression of c-Myc, which does not impact on basal levels of apoptosis, elicited sustained apoptosis in response to DNA damage, suggesting c-Myc activity acts as a crucial cell survival rheostat following DNA damage. We also identify the importance of MYC during DNA damage-induced apoptosis in several other tissues, including the thymus and spleen, using systemic deletion of c-Myc throughout the adult mouse. Together, we have elucidated for the first time in vivo an essential role for endogenous c-Myc in signalling DNA damage-induced apoptosis through the control of the p53 tumour suppressor protein.

  20. Interrelationship between chromosome 8 aneuploidy, C-MYC amplification and increased expression in individuals from northern Brazil with gastric adenocarcinoma

    Institute of Scientific and Technical Information of China (English)

    Danielle Queiroz Calcagno; Márcia Valéria Pitombeira Ferreira; Marília de Arruda Cardoso Smith; Rommel Rodríguez Burbano; Mariana Ferreira Leal; Aline Damaceno Seabra; André Salim Khayat; Elizabeth Suchi Chen; Samia Demachki; Paulo Pimentel Assump(c)(a)o; Mario Henrique Gir(a)o Faria; Silvia Helena Barem Rabenhorst

    2006-01-01

    AIM: To investigate chromosome 8 numerical aberrations, C-MYC oncogene alterations and its expression in gastric cancer and to correlate these findings with histopathological characteristics of gastric tumors.METHODS: Specimens were collected surgically from seven patients with gastric adenocarcinomas. Immunostaining for C-MYC and dual-color fluorescence in situ hybridization (FISH) for C-MYC gene and chromosome 8centromere were performed.RESULTS: All the cases showed chromosome 8 aneuploidy and C-MYC amplification, in both the diffuse and intestinal histopathological types of Lauren. No significant difference (P < 0.05) was observed between the level of chromosome 8 ploidy and the site, stage or histological type of the adenocarcinomas. C-MYC high amplification,like homogeneously stained regions (HSRs) and double minutes (DMs), was observed only in the intestinal-type.Structural rearrangement of C-MYC, like translocation,was observed only in the diffuse type. Regarding C-MYC gene, a significant difference (P < 0.05) was observed between the two histological types. The C-MYC protein was expressed in all the studied cases. In the intestinaltype the C-MYC immunoreactivity was localized only in the nucleus and in the diffuse type in the nucleus and cytoplasm.CONCLUSION: Distinct patterns of alterations between intestinal and diffuse types of gastric tumors support the hypothesis that these types follow different genetic pathways.

  1. HBXIP and LSD1 Scaffolded by lncRNA Hotair Mediate Transcriptional Activation by c-Myc.

    Science.gov (United States)

    Li, Yinghui; Wang, Zhen; Shi, Hui; Li, Hang; Li, Leilei; Fang, Runping; Cai, Xiaoli; Liu, Bowen; Zhang, Xiaodong; Ye, Lihong

    2016-01-15

    c-Myc is regarded as a transcription factor, but the basis for its function remains unclear. Here, we define a long noncoding RNA (lncRNA)/protein complex that mediates the transcriptional activation by c-Myc in breast cancer cells. Among 388 c-Myc target genes in human MCF-7 breast cancer cells, we found that their promoters could be occupied by the oncoprotein HBXIP. We confirmed that the HBXIP expression correlated with expression of the c-Myc target genes cyclin A, eIF4E, and LDHA. RNAi-mediated silencing of HBXIP abolished c-Myc-mediated upregulation of these target genes. Mechanistically, HBXIP interacted directly with c-Myc through the leucine zippers and recruited the lncRNA Hotair along with the histone demethylase LSD1, for which Hotair serves as a scaffold. Silencing of HBXIP, Hotair, or LSD1 was sufficient to block c-Myc-enhanced cancer cell growth in vitro and in vivo. Taken together, our results support a model in which the HBXIP/Hotair/LSD1 complex serves as a critical effector of c-Myc in activating transcription of its target genes, illuminating long-standing questions on how c-Myc drives carcinogenesis.

  2. TIP30 interacts with an estrogen receptor alpha-interacting coactivator CIA and regulates c-myc transcription.

    Science.gov (United States)

    Jiang, Chao; Ito, Mitsuhiro; Piening, Valerie; Bruck, Kristy; Roeder, Robert G; Xiao, Hua

    2004-06-25

    Deregulation of c-myc expression is implicated in the pathogenesis of many neoplasias. Estrogen receptor alpha (ERalpha) can increase the rate of c-myc transcription through the recruitment of a variety of cofactors to the promoter, yet the precise roles of these cofactors in transcription and tumorigenesis are largely unknown. We show here that a putative tumor suppressor TIP30, also called CC3 or Htatip2, interacts with an ERalpha-interacting coactivator CIA. Using chromatin immunoprecipitation assays, we demonstrate that TIP30 and CIA are distinct cofactors that are dynamically associated with the promoter and downstream regions of the c-myc gene in response to estrogen. Both TIP30 and CIA are recruited to the c-myc gene promoter by liganded ERalpha in the second transcription cycle. TIP30 overexpression represses ERalpha-mediated c-myc transcription, whereas TIP30 deficiency enhances c-myc transcription in both the absence and presence of estrogen. Ectopic CIA cooperates with TIP30 to repress ERalpha-mediated c-myc transcription. Moreover, virgin TIP30 knockout mice exhibit increased c-myc expression in mammary glands. Together, these results reveal an important role for TIP30 in the regulation of ERalpha-mediated c-myc transcription and suggest a mechanism for tumorigenesis promoted by TIP30 deficiency.

  3. B lymphocyte-specific c-Myc expression stimulates early and functional expansion of the vasculature and lymphatics during lymphomagenesis.

    Science.gov (United States)

    Ruddell, Alanna; Mezquita, Pau; Brandvold, Kimberly A; Farr, Andrew; Iritani, Brian M

    2003-12-01

    Expression of the c-myc proto-oncogene is deregulated in many human cancers. We examined the role of c-Myc in stimulating angiogenesis and lymphangiogenesis in a highly metastatic murine model of Burkitt's lymphoma (E micro -c-myc), where c-Myc is expressed exclusively in B lymphocytes. Immunohistochemical analysis of bone marrow and lymph nodes from young (preneoplastic) E micro -c-myc transgenic mice revealed increased growth of blood vessels, which are functional by dye flow assay. Lymphatic sinuses also increased in size and number within the lymph nodes, as demonstrated by immunostaining for with a lymphatic endothelial marker 10.1.1. The 10.1.1 antibody recognizes VEGFR-2- and VEGFR-3-positive lymphatic sinuses and vessels within lymph nodes, and also recognizes lymphatic vessels in other tissues. Subcutaneously injected dye traveled more efficiently through draining lymph nodes in E micro -c-myc mice, indicating that these hypertrophic lymphatic sinuses increase lymph flow. Purified B lymphocytes and lymphoid tissues from E micro -c-myc mice expressed increased levels of vascular endothelial growth factor (VEGF) by immunohistochemical or immunoblot assays, which could promote blood and lymphatic vessel growth through interaction with VEGFR-2, which is expressed on the endothelium of both vessel types. These results indicate that constitutive c-Myc expression stimulates angiogenesis and lymphangiogenesis, which may promote the rapid growth and metastasis of c-Myc-expressing cancer cells, respectively.

  4. [Advances Research on C-MYC Proto-oncogene in Multiple Myeloma -Review].

    Science.gov (United States)

    Huang, He; Guo, Wen-Jian; Yao, Ron-Xin

    2016-08-01

    Multiple myeloma(MM) as one of the most common tumors of hmatologic system, is characterized by malignant proliferation of plasma cells, and the chemotherapy is the main therapeutic method. MM is an incurable disease because of drug-resistance of MM cells. Although the pathogenesis of MM remains unknown, the chromosome abnormalities exit in half of the patients, particularly the highly expressed gene C-MYC. Furthermore, plenty of clinical researches indicated a high expression level of C-MYC implied worse progression and/or poor prognosis of MM. Recently, the work exploiting the compounds targeting MYC has made substantial progress, even in the MM therapy. In this article, briefly the recent advances of the research on C-MYC proto-oncogene in multiple myeloma are reviewed.

  5. Cyclin D1 inhibits whereas c-Myc enhances the cytotoxicity of cisplatin in mouse pancreatic cancer cells via regulation of several members of the NF-κB and Bcl-2 families

    Directory of Open Access Journals (Sweden)

    Ayman El-Kady

    2011-01-01

    Full Text Available Background: Cisplatin (CDDP is a drug used for treatment of many types of malignancy but pancreatic cancer is relatively resistant to it. This study aims to determine whether and how cyclin D1 (D1 and c-Myc influence the response of pancreatic cancer cells to CDDP. Materials and Methods: Ela-mycPT mouse pancreatic cancer cells were transfected with D1 or c-myc cDNA and treated with CDDP alone or together with NPCD, an inhibitor of cyclin dependent ckinase (CDK 4 and 6. Reverse transcription followed by polymerase chain reaction (RT-PCR and western blot assays were used to determine the mRNA and protein levels of interested genes. Cell viability was determined using 3-(4, 5-Dimethylthiazol-2-yl-2, 5-diphenyltetrazolium bromide (MTT assay. Results: Treatment of Ela-mycPT1 cells with CDDP caused an increase in c-myc expression but a slightly latent decrease in D1 expression, whereas D1 and c-Myc proteins repressed each other. D1 or c-Myc rendered Ela-mycPT1 cells resistant or sensitive, respectively, to CDDP. D1 induced the expression of several members of the NF-κB family, including RelA, RelB, Nfκb1 and Nfκb2. D1 also induced BIRC5 and several pro-survival members of the Bcl-2 gene family, including Bcl-2, Mcl-1 and Bad while it decreased the level of the pro-apoptotic Noxa. Inhibition of CDK4 or CDK6 kinase activity by NPCD did not affect these effects of D1. In contrast, c-Myc in Ela-mycPT1 and Ela-mycPT4 cells has the opposite effects to D1 on the expression of most of these apoptosis regulating genes. Conclusion: Our results suggest that induction of c-Myc and inhibition of D1 may be mechanisms for CDDP to elicit cytotoxicity. On the other hand, D1 induces whereas c-Myc represses the expression of key NF-κB family members to induce and repress, respectively, the expression of BIRC5 and several Bcl-2 family members, in turn inhibiting or enhancing the response to CDDP.

  6. Perturbation of 14q32 miRNAs-cMYC gene network in osteosarcoma.

    Science.gov (United States)

    Thayanithy, Venugopal; Sarver, Aaron L; Kartha, Reena V; Li, Lihua; Angstadt, Andrea Y; Breen, Matthew; Steer, Clifford J; Modiano, Jaime F; Subramanian, Subbaya

    2012-01-01

    Osteosarcoma (OS) is the common histological form of primary bone cancer and one of the leading aggressive cancers in children under age fifteen. Although several genetic predisposing conditions have been associated with OS the understanding of its molecular etiology is limited. Here, we show that microRNAs (miRNAs) at the chr.14q32 locus are significantly downregulated in osteosarcoma compared to normal bone tissues. Bioinformatic predictions identified that a subset of 14q32 miRNAs (miR-382, miR-369-3p, miR-544 and miR-134) could potentially target cMYC transcript. The physical interaction between these 14q32 miRNAs and cMYC was validated using reporter assays. Further, restoring expression of these four 14q32 miRNAs decreased cMYC levels and induced apoptosis in Saos2 cells. We also show that exogenous expression of 14q32 miRNAs in Saos2 cells significantly downregulated miR-17-92, a transcriptional target of cMYC. The pro-apoptotic effect of 14q32 miRNAs in Saos2 cells was rescued either by overexpression of cMYC cDNA without the 3'UTR or with miR-17-92 cluster. Further, array comparative genomic hybridization studies showed no DNA copy number changes at 14q32 locus in OS patient samples suggesting that downregulation of 14q32 miRNAs are not due to deletion at this locus. Together, our data support a model where the deregulation of a network involving 14q32 miRNAs, cMYC and miR-17-92 miRNAs could contribute to osteosarcoma pathogenesis.

  7. Genetic and genomic analysis modeling of germline c-MYC overexpression and cancer susceptibility

    Directory of Open Access Journals (Sweden)

    Nunes Virginia

    2008-01-01

    Full Text Available Abstract Background Germline genetic variation is associated with the differential expression of many human genes. The phenotypic effects of this type of variation may be important when considering susceptibility to common genetic diseases. Three regions at 8q24 have recently been identified to independently confer risk of prostate cancer. Variation at 8q24 has also recently been associated with risk of breast and colorectal cancer. However, none of the risk variants map at or relatively close to known genes, with c-MYC mapping a few hundred kilobases distally. Results This study identifies cis-regulators of germline c-MYC expression in immortalized lymphocytes of HapMap individuals. Quantitative analysis of c-MYC expression in normal prostate tissues suggests an association between overexpression and variants in Region 1 of prostate cancer risk. Somatic c-MYC overexpression correlates with prostate cancer progression and more aggressive tumor forms, which was also a pathological variable associated with Region 1. Expression profiling analysis and modeling of transcriptional regulatory networks predicts a functional association between MYC and the prostate tumor suppressor KLF6. Analysis of MYC/Myc-driven cell transformation and tumorigenesis substantiates a model in which MYC overexpression promotes transformation by down-regulating KLF6. In this model, a feedback loop through E-cadherin down-regulation causes further transactivation of c-MYC. Conclusion This study proposes that variation at putative 8q24 cis-regulator(s of transcription can significantly alter germline c-MYC expression levels and, thus, contribute to prostate cancer susceptibility by down-regulating the prostate tumor suppressor KLF6 gene.

  8. Perturbation of 14q32 miRNAs-cMYC gene network in osteosarcoma

    Science.gov (United States)

    Thayanithy, Venugopal; Sarver, Aaron L.; Kartha, Reena V.; Lihua, Li; Angstadt, Andrea Y.; Breen, Matthew; Steer, Clifford J.; Modiano, Jaime F.; Subramanian, Subbaya

    2013-01-01

    Osteosarcoma (OS) is the common histological form of primary bone cancer and one of the leading aggressive cancers in children under age fifteen. Although several genetic predisposing conditions have been associated with OS the understanding of its molecular etiology is limited. Here, we show that microRNAs (miRNAs) at the chr.14q32 locus are significantly downregulated in osteosarcoma compared to normal bone tissues. Bioinformatic predictions identified that a subset of 14q32 miRNAs (miR-382, miR-369-3p, miR-544 and miR-134) could potentially target cMYC transcript. The physical interaction between these 14q32 miRNAs and cMYC was validated using reporter assays. Further, restoring expression of these four 14q32 miRNAs decreased cMYC levels and induced apoptosis in Saos2 cells. We also show that exogenous expression of 14q32 miRNAs in Saos2 cells significantly downregulated miR-17∼92, a transcriptional target of cMYC. The pro-apoptotic effect of 14q32 miRNAs in Saos2 cells was rescued either by overexpression of cMYC cDNA without the 3′UTR or with miR-17∼92 cluster. Further, array comparative genomic hybridization studies showed no DNA copy number changes at 14q32 locus in OS patient samples suggesting that downregulation of 14q32 miRNAs are not due to deletion at this locus. Together, our data support a model where the deregulation of a network involving 14q32 miRNAs, cMYC and miR-17∼92 miRNAs could contribute to osteosarcoma pathogenesis. PMID:22037351

  9. Cooperation of Gata3, c-Myc and Notch in malignant transformation of double positive thymocytes.

    Science.gov (United States)

    van Hamburg, Jan Piet; de Bruijn, Marjolein J W; Dingjan, Gemma M; Beverloo, H Berna; Diepstraten, Hans; Ling, Kam-Wing; Hendriks, Rudi W

    2008-06-01

    Gata transcription factors are critical regulators of proliferation and differentiation implicated in various human cancers, but specific genes activated by Gata proteins remain to be identified. We previously reported that enforced expression of Gata3 during T cell development in CD2-Gata3 transgenic mice induced CD4(+)CD8(+) double-positive (DP) T cell lymphoma. Here, we show that the presence of the DO11.10 T-cell receptor transgene, which directs DP cells towards the CD4 lineage, resulted in enhanced lymphoma development and a dramatic increase in thymocyte cell size in CD2-Gata3 transgenic mice. CD2-Gata3 DP cells expressed high levels of the proto-oncogene c-Myc but the Notch1 signaling pathway, which is known to induce c-Myc, was not activated. Gene expression profiling showed that in CD2-Gata3 lymphoma cells transcription of c-Myc and its target genes was further increased. A substantial fraction of CD2-Gata3 lymphomas had trisomy of chromosome 15, leading to an increased c-Myc gene dose. Interestingly, most lymphomas showed high expression of the Notch targets Deltex1 and Hes1, often due to activating Notch1 PEST domain mutations. Therefore, we conclude that enforced Gata3 expression converts DP thymocytes into a pre-malignant state, characterized by high c-Myc expression, whereby subsequent induction of Notch1 signaling cooperates to establish malignant transformation. The finding that Gata3 regulates c-Myc expression levels, in a direct or indirect fashion, may explain the parallel phenotypes of mice with overexpression or deficiency of either of the two transcription factors.

  10. Investigation of multivalent interactions between conjugate of quantum dots with c-Myc peptide tag and the anti-c-Myc antibody by capillary electrophoresis with fluorescence detection.

    Science.gov (United States)

    Wang, Jianhao; Yang, Li; Liu, Li; Wu, Hao; Wang, Jianpeng; Jiang, Pengju; Jiang, Xiyuan; Qiu, Lin

    2016-12-01

    Herein, we report an assay for detecting the binding of a multivalent peptide and antibody within a capillary with the use of fluorescence coupled capillary electrophoresis. Quantum dots and a c-Myc tag containing peptide EQKLISEEDLG4 H6 were injected sequentially and formed a multivalent quantum dot-EQKLISEEDLG4 H6 assembly within the capillary. The efficiency of the quantum dot-peptide self-assembly was affected by the peptide/quantum dot molar ratio, sampling time, and interval time. Finally, the binding of the monoclonal anti-c-Myc antibody and the multivalent quantum dot-EQKLISEEDLG4 H6 ligand was studied using an in-capillary assay. The microscopic dissociation constant for the self-assembly of monoclonal anti-c-Myc antibody and quantum dot-EQKLISEEDLG4 H6 was determined to be 14.1 μM with a stoichiometry of the peptide-antibody complex of 1.7 determined after fitting this to the Hill equation. This method can be further extended to detect a wide range of biomolecule-biomolecule binding interactions.

  11. HSPH1 inhibition downregulates Bcl-6 and c-Myc and hampers the growth of human aggressive B-cell non-Hodgkin lymphoma.

    Science.gov (United States)

    Zappasodi, Roberta; Ruggiero, Giusi; Guarnotta, Carla; Tortoreto, Monica; Tringali, Cristina; Cavanè, Alessandra; Cabras, Antonello D; Castagnoli, Lorenzo; Venerando, Bruno; Zaffaroni, Nadia; Gianni, Alessandro M; De Braud, Filippo; Tripodo, Claudio; Pupa, Serenella M; Di Nicola, Massimo

    2015-03-12

    We have shown that human B-cell non-Hodgkin lymphomas (B-NHLs) express heat shock protein (HSP)H1/105 in function of their aggressiveness. Here, we now clarify its role as a functional B-NHL target by testing the hypothesis that it promotes the stabilization of key lymphoma oncoproteins. HSPH1 silencing in 4 models of aggressive B-NHLs was paralleled by Bcl-6 and c-Myc downregulation. In vitro and in vivo analysis of HSPH1-silenced Namalwa cells showed that this effect was associated with a significant growth delay and the loss of tumorigenicity when 10(4) cells were injected into mice. Interestingly, we found that HSPH1 physically interacts with c-Myc and Bcl-6 in both Namalwa cells and primary aggressive B-NHLs. Accordingly, expression of HSPH1 and either c-Myc or Bcl-6 positively correlated in these diseases. Our study indicates that HSPH1 concurrently favors the expression of 2 key lymphoma oncoproteins, thus confirming its candidacy as a valuable therapeutic target of aggressive B-NHLs.

  12. Cooverexpression of EpCAM and c-myc genes in malignant breast tumours.

    Science.gov (United States)

    Sadeghi, Samira; Hojati, Zohreh; Tabatabaeian, Hossein

    2017-03-01

    The overexpression of epithelial cell adhesion molecule (EpCAM), a proto-oncogene, affects progression, treatment, and diagnosis of many adenocarcinomas. C-myc has been shown to be a downstream target of EpCAM and is also one of the most important proto-oncogenes routinely overexpressed in breast cancer. However, cooverexpression of EpCAM and c-myc genes has not been investigated in breast cancer tissues, particularly in Iranian population. The aim of this study was to assess the expression of EpCAM and c-myc genes in malignant breast cancer tissues using reverse transcriptase-quantitative polymerase chain reaction (RT-qPCR) followed by analyses of the association between the outcomes. In this study, 122 fresh tissues, including 104 malignant and 18 benign samples, were disrupted by mortar and pestle, and then the RNA was isolated from the samples and converted to cDNA. The relative expression levels of EpCAM and c-myc genes were measured by 2(-ΔΔCt) method using RT-qPCR. EpCAM protein level was also assessed in 66 cases using Western blot technique. Using RT-qPCR method, our results showed that EpCAM was overexpressed in 48% of malignant and 11.1% of benign samples. Evaluating EpCAM protein overexpression in a portion of samples depicted the fully concordance rate between Western blot and RT-qPCR techniques. C-myc expression was first evaluated by RT-qPCR method, showing the overexpression rate of 39% and 28% in malignant and benign samples, respectively. These data were also quite concordant with the clinically available immunohistochemistry reports of the same samples studied in this study. Importantly, overexpression of EpCAM and c-myc was significantly associated and showed an agreement of 57.3%. This study demonstrated the cooverexpression of EpCAM and c-myc in breast tumours collected from breast cancer patients of the Iranian population. EpCAM and c-myc positive cases were significantly associated with reduced and enhanced risk of ER/PR positivity

  13. Alterations in TP53, cyclin D2, c-Myc, p21WAF1/CIP1 and p27KIP1 expression associated with progression in B-CLL

    Directory of Open Access Journals (Sweden)

    Antosz Halina

    2010-04-01

    Full Text Available B-cell chronic lymphocytic leukaemia (B-CLL originates from B lymphocytes that may differ in the activationlevel, maturation state or cellular subgroups in peripheral blood. Tumour progression in CLL B cells seems to result in gradualaccumulation of the clone of resting B lymphocytes in the early phases (G0/G1 of the cell cycle. The G1 phase isimpaired in B-CLL. We investigated the gene expression of five key cell cycle regulators: TP 53, c-Myc, cyclin D2,p21WAF1/CIP1 and p27KIP1, which primarily regulate the G1 phase of the cell cycle, or S-phase entry and ultimately controlthe proliferation and cell growth as well as their role in B-CLL progression. The study was conducted in peripheral bloodCLL lymphocytes of 40 previously untreated patients. Statistical analysis of correlations of TP53, cyclin D2, c-Myc,p21WAF1/CIP1 and p27KIP1 expressions in B-CLL patients with different Rai stages demonstrated that the progression of diseasewas accompanied by increases in p53, cyclin D2 and c-Myc mRNA expression. The expression of p27KIP1 was nearlystatistically significant whereas that of p21 WAF1/CIP1 showed no such correlation. Moreover, high expression levels of TP53and c-Myc genes were found to be closely associated with more aggressive forms of the disease requiring earlier therapy.

  14. c-Myc directly regulates the transcription of the NBS1 gene involved in DNA double-strand break repair.

    Science.gov (United States)

    Chiang, Yu-Chi; Teng, Shu-Chun; Su, Yi-Ning; Hsieh, Fon-Jou; Wu, Kou-Juey

    2003-05-23

    The c-myc proto-oncogene encodes a ubiquitous transcription factor involved in the control of cell growth and implicated in inducing tumorigenesis. Understanding the function of c-Myc and its role in cancer depends upon the identification of c-Myc target genes. Nijmegen breakage syndrome (NBS) is a chromosomal-instability syndrome associated with cancer predisposition, radiosensitivity, and chromosomal instability. The NBS gene product, NBS1 (p95 or nibrin), is a part of the hMre11 complex, a central player associated with double-strand break (DSB) repair. NBS1 contains domains characteristic for proteins involved in DNA repair, recombination, and replication. Here we show that c-Myc directly activates NBS1. c-Myc-mediated induction of NBS1 gene transcription occurs in different tissues, is independent of cell proliferation, and is mediated by a c-Myc binding site in the intron 1 region of NBS1 gene. Overexpression of NBS1 in Rat1a cells increased cell proliferation. These results indicate that NBS1 is a direct transcriptional target of c-Myc and links the function of c-Myc to the regulation of DNA DSB repair pathway operating during DNA replication.

  15. Distinct nuclear arrangement of active and inactive c-myc genes in control and differentiated colon carcinoma cells.

    Science.gov (United States)

    Harnicarová, Andrea; Kozubek, Stanislav; Pacherník, Jirí; Krejci, Jana; Bártová, Eva

    2006-12-10

    Using sequential RNA-DNA fluorescence in situ hybridization, the nuclear arrangement of both the active and inactive c-myc gene as well as its transcription was investigated in colon cancer HT-29 cells induced to differentiate into enterocytes. Cytogenetic studies revealed the presence of two chromosomes 8 in HT-29 cells, of which the one containing c-myc gene amplicons was substantially larger and easily distinguished from the normal chromosome. This observation enabled detection of both activity and nuclear localization of c-myc genes in single cells and in individual chromosome territories. Similar transcriptional activity of the c-myc gene was observed in both the normal and derivative chromosome 8 territories showing no influence of the amplification on the c-myc gene expression. Our experiments demonstrate strikingly specific nuclear and territorial arrangements of active genes as compared with inactive ones: on the periphery of their territories facing to the very central region of the cell nucleus. Nuclear arrangement of c-myc genes and transcripts was conserved during cell differentiation and, therefore, independent of the level of differentiation-specific c-myc gene expression. However, after the induction of differentiation, a more internal territorial location was found for the single copy c-myc gene of normal chromosome 8, while amplicons conserved their territorial topography.

  16. Inhibition of c-Myc overcomes cytotoxic drug resistance in acute myeloid leukemia cells by promoting differentiation.

    Directory of Open Access Journals (Sweden)

    Xiao-Na Pan

    Full Text Available Nowadays, drug resistance still represents a major obstacle to successful acute myeloid leukemia (AML treatment and the underlying mechanism is not fully elucidated. Here, we found that high expression of c-Myc was one of the cytogenetic characteristics in the drug-resistant leukemic cells. c-Myc over-expression in leukemic cells induced resistance to chemotherapeutic drugs, enhanced colony formation capacity and inhibited cell differentiation induced by all-trans retinoic acid (ATRA. Meanwhile, inhibition of c-Myc by shRNA or specific c-Myc inhibitor 10058-F4 rescued the sensitivity to cytotoxic drugs, restrained the colony formation ability and promoted differentiation. RT-PCR and western blotting analysis showed that down-regulation of C/EBPβ contributed to the poor differentiation state of leukemic cells induced by c-Myc over-expression. Importantly, over-expression of C/EBPβ could reverse c-Myc induced drug resistance. In primary AML cells, the c-Myc expression was negatively correlated with C/EBPβ. 10058-F4, displayed anti-proliferative activity and increased cellular differentiation with up-regulation of C/EBPβ in primary AML cells. Thus, our study indicated that c-Myc could be a novel target to overcome drug resistance, providing a new approach in AML therapy.

  17. Sensitivity of nuclear c-myc levels and induction to differentiation-inducing agents in human colon tumor cell lines.

    Science.gov (United States)

    Taylor, C W; Kim, Y S; Childress-Fields, K E; Yeoman, L C

    1992-02-29

    Six human colon tumor cell lines were analyzed for their constitutive levels of the c-myc protein. The nuclear proto-oncogene, c-myc, was detected as an expressed product in all of the human colon tumor cell lines analyzed. The poorly differentiated cell lines HCT116, RKO and C showed c-myc levels that averaged 2-fold greater than their well-differentiated counterparts, i.e., GEO, CBS and FET. When c-myc levels and responses to serum induction were analyzed in the presence of inducers of differentiation, i.e., dimethylformamide, retinoic acid, sodium butyrate and TGF-beta, distinct patterns of sensitivity and resistance emerged. Nuclear c-myc levels were reduced in all the colon cell phenotypes treated with dimethylformamide or sodium butyrate. Only the well-differentiated human colon tumor cell lines were responsive to transforming growth factor-beta. Only one of the human colon tumor cell lines (GEO) responded to retinoic acid. Increased levels of c-myc protein were found to correlate well with greater growth rates and with poor differentiation class. Similarly, a parallel sensitivity to down-regulation of c-myc levels and attenuation of c-myc induction curves for inducers of differentiation were observed in growth sensitive human colon tumor cell lines.

  18. Transactivation Domain of Human c-Myc Is Essential to Alleviate Poly(Q)-Mediated Neurotoxicity in Drosophila Disease Models.

    Science.gov (United States)

    Raj, Kritika; Sarkar, Surajit

    2017-03-18

    Polyglutamine (poly(Q)) disorders, such as Huntington's disease (HD) and spinocerebellar ataxias, represent a group of neurological disorders which arise due to an atypically expanded poly(Q) tract in the coding region of the affected gene. Pathogenesis of these disorders inside the cells begins with the assembly of these mutant proteins in the form of insoluble inclusion bodies (IBs), which progressively sequester several vital cellular transcription factors and other essential proteins, and finally leads to neuronal dysfunction and apoptosis. We have shown earlier that targeted upregulation of Drosophila myc (dmyc) dominantly suppresses the poly(Q) toxicity in Drosophila. The present study examines the ability of the human c-myc proto-oncogene and also identifies the specific c-Myc isoform which drives the mitigation of poly(Q)-mediated neurotoxicity, so that it could be further substantiated as a potential drug target. We report for the first time that similar to dmyc, tissue-specific induced expression of human c-myc also suppresses poly(Q)-mediated neurotoxicity by an analogous mechanism. Among the three isoforms of c-Myc, the rescue potential was maximally manifested by the full-length c-Myc2 protein, followed by c-Myc1, but not by c-MycS which lacks the transactivation domain. Our study suggests that strategies focussing on the transactivation domain of c-Myc could be a very useful approach to design novel drug molecules against poly(Q) disorders.

  19. Dose-adjusted Chemotherapy for Untreated c-MYC-positive Lymphoma

    Science.gov (United States)

    In this trial, adult patients with newly diagnosed Burkitt lymphoma or c-MYC-positive DLBCL will be separated into low-risk and high-risk groups; those in the low-risk group will be treated with at least three cycles of dose-adjusted EPOCH-R

  20. c-myc copy number gain is a powerful prognosticator of disease outcome in cervical dysplasia.

    Science.gov (United States)

    Kübler, Kirsten; Heinenberg, Sally; Rudlowski, Christian; Keyver-Paik, Mignon-Denise; Abramian, Alina; Merkelbach-Bruse, Sabine; Büttner, Reinhard; Kuhn, Walther; Schildhaus, Hans-Ulrich

    2015-01-20

    Cervical carcinoma develops from preneoplasia by a multistep process. Although most low-grade dysplastic lesions will regress without intervention and even high-grade changes exhibit a substantial rate of regression, a small percentage of dysplasia will progress over time. Thus, indicators are needed to estimate the biological risk and to help avoid overtreatment in women who desire to preserve fertility. In addition to the classical biomarkers, PCR-ELISA-determined HPV genotype and immunohistochemically assessed p16INK4a and Ki-67 expression, cells with integrated HPV and copy number gain of TERC and c-myc were quantified in a panel of 104 benign, intraepithelial neoplastic (CIN I, II, III) and cancerous lesions using fluorescence in situ hybridization. Optimal cut-off values were calculated; Kaplan-Meier curves and a Cox proportional hazard regression model were used to evaluate prognostic signatures. The assay reliably identified HPV integration, TERC and c-myc copy number gain as determined by comparisons with established biomarkers. All biomarker levels increased with the progression of the disease. However, only c-myc copy number gain independently prognosticated a low probability of dysplastic regression. Our results suggest that c-myc plays a key role in the process of dysplastic transformation and might thus be exploited for treatment and follow-up decision-making of cervical dysplasia.

  1. cMyc Regulates the Size of the Premigratory Neural Crest Stem Cell Pool.

    Science.gov (United States)

    Kerosuo, Laura; Bronner, Marianne E

    2016-12-06

    The neural crest is a transient embryonic population that originates within the central nervous system (CNS) and then migrates into the periphery and differentiates into multiple cell types. The mechanisms that govern neural crest stem-like characteristics and self-renewal ability are poorly understood. Here, we show that the proto-oncogene cMyc is a critical factor in the chick dorsal neural tube, where it regulates the size of the premigratory neural crest stem cell pool. Loss of cMyc dramatically decreases the number of emigrating neural crest cells due to reduced self-renewal capacity, increased cell death, and shorter duration of the emigration process. Interestingly, rather than via E-Box binding, cMyc acts in the dorsal neural tube by interacting with another transcription factor, Miz1, to promote self-renewal. The finding that cMyc operates in a non-canonical manner in the premigratory neural crest highlights the importance of examining its role at specific time points and in an in vivo context.

  2. Cooverexpression of EpCAM and c-myc genes in malignant breast tumours

    Indian Academy of Sciences (India)

    SAMIRA SADEGHI; ZOHREH HOJATI; HOSSEIN TABATABAEIAN

    2017-03-01

    The overexpression of epithelial cell adhesion molecule (EpCAM), a proto-oncogene, affects progression, treatment, and diagnosis of many adenocarcinomas. C-myc has been shown to be a downstream target of EpCAM and is also one of the most important proto-oncogenes routinely overexpressed in breast cancer. However, cooverexpression of EpCAM and c-mycgenes has not been investigated in breast cancer tissues, particularly in Iranian population. The aim of this study was to assess the expression of EpCAM and c-myc genes in malignant breast cancer tissues using reverse transcriptase-quantitative polymerase chain reaction (RT-qPCR) followed by analyses of the association between the outcomes. In this study, 122 fresh tissues, including 104 malignant and 18 benign samples, were disrupted by mortar and pestle, and then the RNA was isolated from the samples and converted to cDNA. The relative expression levels of EpCAM and c-myc genes were measured by2−ΔΔCt method using RT-qPCR. EpCAM protein level was also assessed in 66 cases using Western blot technique. UsingRT-qPCR method, our results showed that EpCAM was overexpressed in 48% of malignant and 11.1% of benign samples. Evaluating EpCAM protein overexpression in a portion of samples depicted the fully concordance rate between Western blot and RT-qPCR techniques. C-myc expression was first evaluated by RT-qPCR method, showing the overexpression rate of 39%and 28% in malignant and benign samples, respectively. These data were also quite concordant with the clinically available immunohistochemistry reports of the same samples studied in this study. Importantly, overexpression of EpCAM and c-myc was significantly associated and showed an agreement of 57.3%. This study demonstrated the cooverexpression of EpCAM and c-myc in breast tumours collected from breast cancer patients of the Iranian population. EpCAM and c-myc positive cases were significantly associated with reduced and enhanced risk of ER/PR positivity

  3. Overexpression of c-myc is associated with adverse clinical features and worse overall survival in multiple myeloma

    DEFF Research Database (Denmark)

    Szabo, Agoston Gyula; Gang, Anne Ortved; Pedersen, Mette Ølgod

    2016-01-01

    The role of c-myc in multiple myeloma (MM) is controversial. We conducted a retrospective study of 117 patients with MM diagnosed between 2004 and 2010 at Herlev Hospital. Immunohistochemistry (IHC) and fluorescent in situ hybridization (FISH) were performed on tissue microarrays (TMAs) made from...... diagnostic bone marrow aspirates. Clinical data were obtained from the Danish Multiple Myeloma Database (DMMD). Overexpression of c-myc was found in 40% of patients. MYC translocation was found in 10% of patients. Overexpression of c-myc was not associated with MYC translocation. Overexpression of c-myc...... was associated with hypercalcemia (p = 0.02) and extramedullary myeloma (p c-myc was associated with shorter overall survival (OS) by multivariable analysis of the entire patient cohort [HR 1.92 (1.06-3.45), p = 0.03] and univariable analysis of high-dose-therapy (HDT...

  4. [Clinical features in DLBCL and translocation BCL2/c-MYC "double hit" lymphoma].

    Science.gov (United States)

    Škunca, Željka; Domimis, Mara; Plninc-Peraica, Ana; Jakšić, Branimir

    2014-06-01

    Diffuse large B-cell lymphoma (DLBCL) is classified as lymphoma and various entities using the gene expression of proteins are classified into three groups. The aim of this study was to clarify the clinical, biological, immunophenotypic and cytogenetic features of DLBCL with translocation t (14; 18) and 8q24/c-MYC. Eleven DLBCL patients with dual translation were monitored during the 2000-2009 period. The characteristics of these patients included morphological, immunohistochemical and cytogenetic analysis. Study results showed that all patients had aggressive characteristics, presence of B symptoms (64%), general patient condition according to ECOG scale ≥ 2 (55%), elevated serum lactate dehydrogenase activity (73%), clinical stage III and IV (82%), extranodal involvement of the disease (73%), and IPI ≥ 2 (73%). Partial remission was achieved in 73% of all patients and all patients (73%) died within a short time. Patients were treated with CHOP and similar protocols (COP, CVP, CNOP), with the addition of MabThera. Immunophenotyping was performed and determined expression of the CD20, CD3, CD10, BCL6 and MUM1 markers. The cytogenetic analysis/fluorescence in situ hybridization revealed complex karyotype changes. Thus, we analyzed the presence of BCL2, BCL6 and c-MYC genes and found eight patients to have BCL2 and c-MYC translocation genes, while three had translocation of the BCL6 and c-MYC genes. Despite appropriate therapy, the patient prognosis is poor. The median survival in these patients was 1.85 years. DLBCL with BCL2 and c-MYC rearrangement of the subgroups of lymphoma is associated with very poor survival. The presence of these two translocations has an aggressive clinical course.

  5. Oncogene amplification detected by in situ hybridization in radiation induced rat skin tumors. [C-myc:a3

    Energy Technology Data Exchange (ETDEWEB)

    Yi Jin.

    1991-02-01

    Oncogene activation may play an important role in radiation induced carcinogenesis. C-myc oncogene amplification was detected by in situ hybridization in radiation-induced rat skin tumors, including squamous and basal cell carcinomas. In situ hybridization was performed with a biotinylated human c-myc third exon probe, visualized with an avidin-biotinylated alkaline phosphate detection system. No c-myc oncogene amplification was detected in normal rat skin at very early times after exposure to ionizing radiation, which is consistent with the view that c-myc amplification is more likely to be related to carcinogenesis than to normal cell proliferation. The incorporation of tritiated thymidine into the DNA of rat skin cells showed that the proliferation of epidermal cells reached a peak on the seventh day after exposure to ionizing radiation and then decreased. No connection between the proliferation of epidermal cell and c-myc oncogene amplification in normal or irradiated rat skin was found. The results indicated that c-myc amplification as measured by in situ hybridization was correlated with the Southern bolt results, but only some of the cancer cells were amplified. The c-myc positive cells were distributed randomly within regions of the tumor and exhibited a more uniform nuclear structure in comparison to the more vacuolated c-myc negative cells. No c-myc signal was detected in unirradiated normal skin or in irradiated skin cells near the tumors. C-myc amplification appears to be cell or cell cycle specific within radiation-induced carcinomas. 28 refs., 3 figs., 3 tabs.

  6. The Histone Acetyltransferase GCN5 Expression Is Elevated and Regulated by c-Myc and E2F1 Transcription Factors in Human Colon Cancer

    Science.gov (United States)

    Yin, Yan-Wei; Jin, Hong-Jian; Zhao, Wenjing; Gao, Beixue; Fang, Jiangao; Wei, Junmin; Zhang, Donna D.; Zhang, Jianing; Fang, Deyu

    2017-01-01

    The histone acetyltransferase GCN5 has been suggested to be involved in promoting cancer cell growth. But its role in human colon cancer development remains unknown. Herein we discovered that GCN5 expression is significantly upregulated in human colon adenocarcinoma tissues. We further demonstrate that GCN5 is upregulated in human colon cancer at the mRNA level. Surprisingly, two transcription factors, the oncogenic c-Myc and the proapoptotic E2F1, are responsible for GCN5 mRNA transcription. Knockdown of c-Myc inhibited colon cancer cell proliferation largely through downregulating GCN5 transcription, which can be fully rescued by the ectopic GCN5 expression. In contrast, E2F1 expression induced human colon cancer cell death, and suppression of GCN5 expression in cells with E2F1 overexpression further facilitated cell apoptosis, suggesting that GCN5 expression is induced by E2F1 as a possible negative feedback in suppressing E2F1-mediated cell apoptosis. In addition, suppression of GCN5 with its specific inhibitor CPTH2 inhibited human colon cancer cell growth. Our studies reveal that GCN5 plays a positive role in human colon cancer development, and its suppression holds a great therapeutic potential in antitumor therapy. PMID:26637399

  7. Expressão dos protooncogenes c-fos, c-myc e c-jun em miométrio normal e mioma humanos Expression of the protooncogenes c-fos, c-myc and c-jun in human normal miometrium and leiomyoma

    Directory of Open Access Journals (Sweden)

    Ana Luiza Ferrari

    2006-10-01

    Full Text Available OBJETIVO: Comparar a expressão gênica (mRNA e protéica dos protooncogenes c-fos, c-myc e c-jun em miométrio normal e mioma humanos. MÉTODOS: Foi realizado um estudo do tipo caso-controle. O material foi coletado de 12 pacientes submetidas a histerectomia no Hospital de Clínicas de Porto Alegre. A expressão do mRNA específico para c-myc, c-fos, c-jun e beta-microglobulina foi avaliada pela técnica de RT-PCR, utilizando primers específicos para cada gene. A expressão protéica destes protooncogenes foi avaliada através de Western blot com anticorpos específicos. RESULTADOS: Não houve diferença significativa para expressão gênica desses protooncogenes entre miométrio normal e mioma (c-myc: 0,87 ± 0,08 vs 0,87 ± 0,08, p = 0,952; c-fos: 1,10 ± 0,17 vs 1,01 ± 0,11, p = 0,21; c-jun: 1,03 ± 0,12 vs 0,96 ± 0,09, p = 0,168, respectivamente. Não houve diferença significativa para expressão protéica desses protooncogenes entre miométrio normal e mioma (c-myc: 1,36 ± 0,48 vs 1,53 ± 0,29, p = 0,569; c-fos: 8,85 ± 5,5 vs 6,56 ± 4,22, p = 0,434; e c-jun: 6,47 ± 3,04 vs 5,42 ± 2,03, p = 0,266, respectivamente. CONCLUSÃO: A expressão gênica (transcrição e a expressão protéica (tradução dos protooncogenes c-myc, c-fos e c-jun em mioma e miométrio normal são semelhantes.Uterine myomas are common benign tumors of the female genital tract. The expression of growth factor signal transduction cascade components including the protooncogenes c-myc, c-fos, and c-jun seem to be involved in the development of myomas. PURPOSE: To compare the gene (mRNA and protein expression of the protooncogenes c-fos, c-myc, and c-jun in human normal myometrium and leiomyoma. METHOD: A case-control study was performed. Samples were collected from 12 patients submitted to hysterectomy at the Hospital de Clínicas at Porto Alegre. The expression of the specific mRNA for c-myc, c-fos, c-jun, and beta-microglobulin was assessed through the RT

  8. Fragile X mental retardation protein control of neuronal mRNA metabolism: Insights into mRNA stability.

    Science.gov (United States)

    De Rubeis, Silvia; Bagni, Claudia

    2010-01-01

    The fragile X mental retardation protein (FMRP) is an RNA binding protein that has an essential role in neurons. From the soma to the synapse, FMRP is associated with a specific subset of messenger RNAs and controls their posttranscriptional fates, i.e., dendritic localization and local translation. Because FMRP target mRNAs encode important neuronal proteins, the deregulation of their expression in the absence of FMRP leads to a strong impairment of synaptic function. Here, we review emerging evidence indicating a critical role for FMRP in the control of mRNA stability. To date, two mRNAs have been identified as being regulated in this manner: PSD-95 mRNA, encoding a scaffolding protein, and Nxf1 mRNA, encoding a general export factor. Moreover, expression studies suggest that the turnover of other neuronal mRNAs, including those encoding for the GABA(A) receptors subunits, could be affected by the loss of FMRP. According to the specific target and/or cellular context, FMRP could influence mRNA stability in the brain. Copyright 2009 Elsevier Inc. All rights reserved.

  9. Alterations of c-Myc and c-erbB-2 genes in ovarian tumours

    Directory of Open Access Journals (Sweden)

    Pastor Tibor

    2009-01-01

    Full Text Available Introduction. According to clinical and epidemiological studies, ovarian cancer ranks fifth in cancer deaths among women. The causes of ovarian cancer remain largely unknown but various factors may increase the risk of developing it, such as age, family history of cancer, childbearing status etc. This cancer results from a succession of genetic alterations involving oncogenes and tumour suppressor genes, which have a critical role in normal cell growth regulation. Mutations and/or overexpression of three oncogenes, c-erbB-2, c-Myc and K-ras, and of the tumour suppressor gene p53, have been frequently observed in a sporadic ovarian cancer. Objective. The aim of the present study was to analyze c-Myc and c-erbB-2 oncogene alterations, specifically amplification, as one of main mechanisms of their activation in ovarian cancers and to establish a possible association with the pathogenic process. Methods. DNA was isolated from 15 samples of malignant and 5 benign ovarian tumours, using proteinase K digestion, followed by phenol-chloroform isoamyl extraction and ethanol precipitation. C-Myc and c-erbB-2 amplification were detected by differential PCR. The level of gene copy increase was measured using the Scion image software. Results. The amplification of both c-Myc and c-erbB-2 was detected in 26.7% of ovarian epithelial carcinoma specimens. Only one tumour specimen concomitantly showed increased gene copy number for both studied genes. Interestingly, besides amplification, gene deletion was also detected (26.7% for c-erbB-2. Most of the ovarian carcinomas with alterations in c-Myc and c-erbB-2 belonged to advanced FIGO stages. Conclusion. The amplification of c-Myc and c-erbB-2 oncogenes in ovarian epithelial carcinomas is most probably a late event in the pathogenesis conferring these tumours a more aggressive biological behaviour. Similarly, gene deletions point to genomic instability in epithelial carcinomas in higher clinical stages as the

  10. C-MYC transcriptionally amplifies SOX2 target genes to regulate self-renewal in multipotent otic progenitor cells.

    Science.gov (United States)

    Kwan, Kelvin Y; Shen, Jun; Corey, David P

    2015-01-13

    Sensorineural hearing loss is caused by the loss of sensory hair cells and neurons of the inner ear. Once lost, these cell types are not replaced. Two genes expressed in the developing inner ear are c-Myc and Sox2. We created immortalized multipotent otic progenitor (iMOP) cells, a fate-restricted cell type, by transient expression of C-MYC in SOX2-expressing otic progenitor cells. This activated the endogenous C-MYC and amplified existing SOX2-dependent transcripts to promote self-renewal. RNA-seq and ChIP-seq analyses revealed that C-MYC and SOX2 occupy over 85% of the same promoters. C-MYC and SOX2 target genes include cyclin-dependent kinases that regulate cell-cycle progression. iMOP cells continually divide but retain the ability to differentiate into functional hair cells and neurons. We propose that SOX2 and C-MYC regulate cell-cycle progression of these cells and that downregulation of C-MYC expression after growth factor withdrawal serves as a molecular switch for differentiation. Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.

  11. [Effect of flumatinib mesylate on C-MYC, HIF-1α and VEGF in U226 line].

    Science.gov (United States)

    Chang, Ming-Xing; Ma, Yan-Ping

    2013-12-01

    The objective of this study was to investigate the effect of the new generation of tyrosine kinase inhibitor flumatinib mesylate on C-MYC, HIF-1α and VEGF in multiple myeloma (MM) cell line U266. Different concentrations (1, 5, 10 µmol/L) of flumatinib mesylate were used to act on U266 cell line for 8, 16 and 24 h, and the expression of C-MYC, and HIF-1α genes was detected by real-time fluorescence-quantitative PCR, the expression of C-MYC, HIF-1α and VEGF was measured by Western blot. The results showed that the gene expression of C-MYC and HIF-1 genes decreased gradually with the increasing of flumatinib mesylate concentration (P C-MYC and HIF-1α gene decreased gradually with prolonging of treatment time with the flumatinib mesylate (P C-MYC, HIF-1α and VEGF decreased gradually with the increasing of flumatinib mesylate concentration (P C-MYC, HIF-1 α and VEGF in U266 cell line in a time- and dose-dependent manners, so flumatinib mesylate may become a new drug for MM therapy.

  12. Not All G-Quadruplexes are Created Equally: An Investigation of the Structural Polymorphism of the c-Myc G-Quadruplex-Forming Sequence and its Interaction with the Porphyrin meso-Tetra(N-methyl-4-pyridyl)porphine

    Science.gov (United States)

    Le, Huy T.; Miller, M. Clarke; Buscaglia, Robert; Dean, William L.; Holt, Patrick A.; Chaires, Jonathan B.; Trent, John O.

    2012-01-01

    G-quadruplexes, DNA tertiary structures highly localized to functionally important sites within the human genome, have emerged as important new drug targets. The putative G-quadruplex-forming sequence (Pu27) in the NHE-III1 promoter region of the c-Myc gene is of particular interest as stabilization of this G-quadruplex with TMPyP4 has been shown to repress c-Myc transcription. In this study, we examine the Pu27 G-quadruplex-forming sequence and its interaction with TMPyP4. We report that the Pu27 sequence exists as a heterogeneous mixture of monomeric and higher-order G-quadruplex species in vitro and that this mixture can be partially resolved by size exclusion chromatography (SEC) separation. Within this ensemble of configurations, the equilibrium can be altered by modifying the buffer composition, annealing procedure, and dialysis protocol thereby affecting the distribution of G-quadruplex species formed. TMPyP4 was found to bind preferentially to higher-order G-quadruplex species suggesting the possibility of stabilization of the junctions of the c-Myc G-quadruplex multimers by porphyrin end-stacking. We also examined four modified c-Myc sequences that have been previously reported and found a narrower distribution of quadruplex configurations compared to the parent Pu27 sequence. We could not definitively conclude whether these G-quadruplex structures were selected from the original ensemble or if they are new G-quadruplex structures. Since these sequences differ considerably from the wild-type promoter sequence, it is unclear whether their structures have any actual biological relevance. Additional studies are needed to examine how the polymorphic nature of G-quadruplexes affects the interpretation of in vitro data for c-Myc and other G-quadruplexes. The findings reported here demonstrate that experimental conditions contribute significantly to G-quadruplex formation and should be carefully considered, controlled, and reported in detail. PMID:23108607

  13. c-Myc/Max heterodimers bind cooperatively to the E-box sequences located in the first intron of the rat ornithine decarboxylase (ODC) gene

    NARCIS (Netherlands)

    Walhout, A.J.M.; Gubbels, J.M.; Bernards, R.A.; Vliet, P.C. van der; Timmers, H.T.M.

    1997-01-01

    The oncoprotein c-Myc plays an important role in cell proliferation, transformation, inhibition of differentiation and apoptosis. These functions most likely result from the transcription factor activity of c-Myc. As a heterodimer with Max, the c-Myc protein binds to the E-box sequence (CACGTG), whi

  14. Repression of c-Myc responsive genes in cycling cells causes G1 arrest through reduction of cyclin E/CDK2 kinase activity

    NARCIS (Netherlands)

    Berns, K.; Hijmans, E.M.; Bernards, R.A.

    1997-01-01

    The c-myc gene encodes a sequence-specific DNA binding protein involved in proliferation and oncogenesis. Activation of c-myc expression in quiescent cells is sufficient to mediate cell cycle entry, whereas inhibition of c-myc expression causes cycling cells to withdraw from the cell cycle. To searc

  15. Inversed relationship between CD44 variant and c-Myc due to oxidative stress-induced canonical Wnt activation

    Energy Technology Data Exchange (ETDEWEB)

    Yoshida, Go J., E-mail: medical21go@yahoo.co.jp; Saya, Hideyuki

    2014-01-10

    Highlights: •CD44 variant8–10 and c-Myc are inversely expressed in gastric cancer cells. •Redox-stress enhances c-Myc expression via canonical Wnt signal. •CD44v, but not CD44 standard, suppresses redox stress-induced Wnt activation. •CD44v expression promotes both transcription and proteasome degradation of c-Myc. •Inversed expression pattern between CD44v and c-Myc is often recognized in vivo. -- Abstract: Cancer stem-like cells express high amount of CD44 variant8-10 which protects cancer cells from redox stress. We have demonstrated by immunohistochemical analysis and Western blotting, and reverse-transcription polymerase chain reaction, that CD44 variant8-10 and c-Myc tend to show the inversed expression manner in gastric cancer cells. That is attributable to the oxidative stress-induced canonical Wnt activation, and furthermore, the up-regulation of the downstream molecules, one of which is oncogenic c-Myc, is not easily to occur in CD44 variant-positive cancer cells. We have also found out that CD44v8-10 expression is associated with the turn-over of the c-Myc with the experiments using gastric cancer cell lines. This cannot be simply explained by the model of oxidative stress-induced Wnt activation. CD44v8-10-positive cancer cells are enriched at the invasive front. Tumor tissue at the invasive area is considered to be composed of heterogeneous cellular population; dormant cancer stem-like cells with CD44v8-10 {sup high}/ Fbw7 {sup high}/ c-Myc {sup low} and proliferative cancer stem-like cells with CD44v8-10 {sup high}/ Fbw7 {sup low}/ c-Myc {sup high}.

  16. Mechanistic studies for the role of cellular nucleic-acid-binding protein (CNBP) in regulation of c-myc transcription.

    Science.gov (United States)

    Chen, Siqi; Su, Lijuan; Qiu, Jun; Xiao, Nannan; Lin, Jing; Tan, Jia-Heng; Ou, Tian-Miao; Gu, Lian-Quan; Huang, Zhi-Shu; Li, Ding

    2013-10-01

    Guanine-rich sequence of c-myc nuclease hypersensitive element (NHE) III1 is known to fold in G-quadruplex and subsequently serves as a transcriptional silencer. Cellular nucleic-acid-binding protein (CNBP), a highly conserved zinc-finger protein with multiple biological functions, could bind to c-myc NHE III1 region, specifically to the single strand G-rich sequence. In the present study, a variety of methods, including cloning, expression and purification of protein, EMSA, CD, FRET, Ch-IP, RNA interference, luciferase reporter assay, SPR, co-immunoprecipitation, and co-transfection, were applied to investigate the mechanism for the role of CNBP in regulating c-myc transcription. We found that human CNBP specifically bound to the G-rich sequence of c-myc NHE III1 region both in vitro and in cellulo, and subsequently promoted the formation of G-quadruplex. CNBP could induce a transient decrease followed by an increase in c-myc transcription in vivo. The interaction of CNBP with NM23-H2 was responsible for the increase of c-myc transcription. Based on above experimental results, a new mechanism, involving G-quadruplex related CNBP/NM23-H2 interaction, for the regulation of c-myc transcription was proposed. These findings indicated that the regulation of c-myc transcription through NHE III1 region might be governed by mechanisms involving complex protein-protein interactions, and suggested a new possibility of CNBP as a potential anti-cancer target based on CNBP's biological function in c-myc transcription. Copyright © 2013 Elsevier B.V. All rights reserved.

  17. SIRT1 and c-Myc Promote Liver Tumor Cell Survival and Predict Poor Survival of Human Hepatocellular Carcinomas

    Science.gov (United States)

    Jang, Kyu Yun; Noh, Sang Jae; Lehwald, Nadja; Tao, Guo-Zhong; Bellovin, David I.; Park, Ho Sung; Moon, Woo Sung; Felsher, Dean W.; Sylvester, Karl G.

    2012-01-01

    The increased expression of SIRT1 has recently been identified in numerous human tumors and a possible correlation with c-Myc oncogene has been proposed. However, it remains unclear whether SIRT1 functions as an oncogene or tumor suppressor. We sought to elucidate the role of SIRT1 in liver cancer under the influence of c-Myc and to determine the prognostic significance of SIRT1 and c-Myc expression in human hepatocellular carcinoma. The effect of either over-expression or knock down of SIRT1 on cell proliferation and survival was evaluated in both mouse and human liver cancer cells. Nicotinamide, an inhibitor of SIRT1, was also evaluated for its effects on liver tumorigenesis. The prognostic significance of the immunohistochemical detection of SIRT1 and c-Myc was evaluated in 154 hepatocellular carcinoma patients. SIRT1 and c-Myc regulate each other via a positive feedback loop and act synergistically to promote hepatocellular proliferation in both mice and human liver tumor cells. Tumor growth was significantly inhibited by nicotinamide in vivo and in vitro. In human hepatocellular carcinoma, SIRT1 expression positively correlated with c-Myc, Ki67 and p53 expression, as well as high á-fetoprotein level. Moreover, the expression of SIRT1, c-Myc and p53 were independent prognostic indicators of hepatocellular carcinoma. In conclusion, this study demonstrates that SIRT1 expression supports liver tumorigenesis and is closely correlated with oncogenic c-MYC expression. In addition, both SIRT1 and c-Myc may be useful prognostic indicators of hepatocellular carcinoma and SIRT1 targeted therapy may be beneficial in the treatment of hepatocellular carcinoma. PMID:23024800

  18. Site-Specific Oligonucleotide Binding Represses Transcription of the Human c-myc Gene in vitro

    Science.gov (United States)

    Cooney, Michael; Czernuszewicz, Graznya; Postel, Edith H.; Flint, S. Jane; Hogan, Michael E.

    1988-07-01

    A 27-base-long DNA oligonucleotide was designed that binds to duplex DNA at a single site within the 5' end of the human c-myc gene, 115 base pairs upstream from the transcription origin P1. On the basis of the physical properties of its bound complex, it was concluded that the oligonucleotide forms a colinear triplex with the duplex binding site. By means of an in vitro assay system, it was possible to show a correlation between triplex formation at -115 base pairs and repression of c-myc transcription. The possibility is discussed that triplex formation (site-specific RNA binding to a DNA duplex) could serve as the basis for an alternative program of gene control in vivo.

  19. Expression of c-myc gene as an early indicator of late radiation damage of kidney

    Energy Technology Data Exchange (ETDEWEB)

    Otsuka, Makoto; Hatakenaka, Masamitsu [Kyushu Univ., Fukuoka (Japan). Dept. of Genetics Medical Inst. of Bioregulation; Masuda, Koji

    1998-02-01

    We have previously described the increased proliferation and appearance of abnormally large nuclei in renal proximal tubule cells after radiation. A model has been proposed that the large nuclear cells might be dying and the increased proliferation might lead to mitotic death of these cells and cause functional damage. We measured the amount of c-myc transcript taking the ratio of densities of bands for irradiated left kidney to unirradiated right kidney after RT-PCR procedure on 24 hours after 9, 12 and 15 Gy irradiation, and found positive in 1 out of 10 after 9 Gy, 6 out of 10 after 12 Gy and 9 out of 10 after 15 Gy. Measuring c-myc expression seems to be a potential very early indicator of late radiation damage of kidney. (author)

  20. Nemorubicin and doxorubicin bind the G-quadruplex sequences of the human telomeres and of the c-MYC promoter element Pu22.

    Science.gov (United States)

    Scaglioni, Leonardo; Mondelli, Rosanna; Artali, Roberto; Sirtori, Federico Riccardi; Mazzini, Stefania

    2016-06-01

    Intra-molecular G-quadruplex structures are present in the guanine rich regions of human telomeres and were found to be prevalent in gene promoters. More recently, the targeting of c-MYC transcriptional control has been suggested, because the over expression of the c-MYC oncogene is one of the most common aberration found in a wide range of human tumors. The interaction of nemorubicin and doxorubicin with DNA G-quadruplex structures has been studied by NMR, ESI-MS and molecular modelling, in order to obtain further information about the complex and the multiple mechanisms of action of these drugs. Nemorubicin intercalates between A3 and G4 of d(TTAGGGT)4 and form cap-complex at the G6pT7 site. The presence of the adenine in this sequence is important for the stabilization of the complex, as was shown by the interaction with d(TTGGGTT)4 and d(TTTGGGT)4, which form only a 1:1 complex. The interaction of doxorubicin with d(TTAGGGT)4 is similar, but the complex appears less stable. Nemorubicin also binds with high efficiency the c-MYC G-quadruplex sequence Pu22, to form a very well defined complex. Two nemorubicin molecules bind to the 3'-end and to the 5'-end, forming an additional plane of stacking over each external G-tetrad. The wild type c-MYCPu22 sequence forms with nemorubicin the same complex. Nemorubicin and doxorubicin, not only intercalate into the duplex DNA, but also result in significant ligands for G-quadruplex DNA segments, stabilizing their structure; this may in part explain the multiple mechanisms of action of their antitumor activity. Copyright © 2016 Elsevier B.V. All rights reserved.

  1. Targeting of the MYCN protein with small molecule c-MYC inhibitors.

    Directory of Open Access Journals (Sweden)

    Inga Müller

    Full Text Available Members of the MYC family are the most frequently deregulated oncogenes in human cancer and are often correlated with aggressive disease and/or poorly differentiated tumors. Since patients with MYCN-amplified neuroblastoma have a poor prognosis, targeting MYCN using small molecule inhibitors could represent a promising therapeutic approach. We have previously demonstrated that the small molecule 10058-F4, known to bind to the c-MYC bHLHZip dimerization domain and inhibiting the c-MYC/MAX interaction, also interferes with the MYCN/MAX dimerization in vitro and imparts anti-tumorigenic effects in neuroblastoma tumor models with MYCN overexpression. Our previous work also revealed that MYCN-inhibition leads to mitochondrial dysfunction resulting in accumulation of lipid droplets in neuroblastoma cells. To expand our understanding of how small molecules interfere with MYCN, we have now analyzed the direct binding of 10058-F4, as well as three of its analogs; #474, #764 and 10058-F4(7RH, one metabolite C-m/z 232, and a structurally unrelated c-MYC inhibitor 10074-G5, to the bHLHZip domain of MYCN. We also assessed their ability to induce apoptosis, neurite outgrowth and lipid accumulation in neuroblastoma cells. Interestingly, all c-MYC binding molecules tested also bind MYCN as assayed by surface plasmon resonance. Using a proximity ligation assay, we found reduced interaction between MYCN and MAX after treatment with all molecules except for the 10058-F4 metabolite C-m/z 232 and the non-binder 10058-F4(7RH. Importantly, 10074-G5 and 10058-F4 were the most efficient in inducing neuronal differentiation and lipid accumulation in MYCN-amplified neuroblastoma cells. Together our data demonstrate MYCN-binding properties for a selection of small molecules, and provide functional information that could be of importance for future development of targeted therapies against MYCN-amplified neuroblastoma.

  2. The c-myc coding DNA sequences of cyprinids (Teleostei: Cypriniformes): Implications for phylogeny

    Institute of Scientific and Technical Information of China (English)

    KONG XiangHui; WANG XuZhen; GAN XiaoNi; HE ShunPing

    2007-01-01

    The family Cyprinidae is one of the largest fish families in the world, which is widely distributed in East Asian, with obvious difference in characteristic size among species. The phylogenetic analysis of cyprinid taxa based on the functionally important genes can help to understand the speciation and functional divergence of the Cyprinidae. The c-myc gene is an important gene regulating individual growth.In the present study, the sequence variations of the cyprinid c-myc gene and their phylogenetic significance were analyzed. The 41 complete sequences of the c-myc gene were obtained from cyprinids and outgroups through PCR amplification and clone. The coding DNA sequences of the c-myc gene were used to infer molecular phylogenetic relationships within the Cyprinidae. Myxocyprinus asiaticus (Catostomidae), Misgurnus anguillicaudatus (Cobitidae) and Hemimyzon sinensis (Homalopteridae)were assigned to the outgroup taxa. Phylogenetic analyses using maximum parsimony (MP), maximum likelihood (ML), and Bayesian retrieved similar topology. Within the Cyprinidae, Leuciscini and Barbini formed the monophyletic lineage respectively with high nodal supports. Leuciscini comprises Xenocyprinae, Cultrinae, East Asian species of Leuciscinae and Danioninae, Gobioninae and Acheilognathinae, and Barbini contains Schizothoracinae, Barbinae, Cyprininae and Labeoninae. Danio rerio, D.myersi and Rasbora trilineata were supposed to separate from Leuciscinae and Barbini and to form another lineage. The positions of some Danioninae species were still unresolved. Analyses of both amino acid variation with parsimony information and two high variation regions indicated that there is no correlation between variations of single amino acid or high variation regions and characteristic size of cyprinids. In addition, the species with smaller size were usually found to be basal within clades in the tree, which might be the results of the adaptation to the primitive ecology and survival pressure.

  3. Astroglial c-Myc overexpression predisposes mice to primary malignant gliomas

    DEFF Research Database (Denmark)

    Jensen, Niels Aagaard; Pedersen, Karen-Marie; Lihme, Frederikke

    2003-01-01

    in the ventricular zone and, analogous to human glioblastomas, exhibit molecular and morphological heterogeneity. Levels of connexin 43 in the majority of the tumors are unaltered from normal tissue, indicating that GEM tumors have retained the capacity to establish syncytial networks. In line with this, individual...... the neoplastic process, presumably by inducing the sustained growth of early astroglial cells. This is in contrast to most other transgenic studies in which c-Myc overexpression requires co-operating transgenes for rapid tumor induction....

  4. Antisense regulation of expression and transactivation functions of the tumorigenic HBx and c-myc genes.

    Science.gov (United States)

    Hung, Le; Kumar, Vijay

    2006-05-26

    Earlier we have shown that the X-myc transgenic mice develop hepatocellular carcinoma (HCC) due to co-expression of c-Myc and HBx protein of hepatitis B virus [R. Lakhtakia, V. Kumar, H. Reddi, M. Mathur, S. Dattagupta, S.K. Panda, Hepatocellular carcinoma in a hepatitis B 'x' transgenic mouse model: a sequential pathological evaluation. J. Gastroenterol. Hepatol. 18 (2003) 80-91]. With the aim to develop therapeutic strategies for HCC, we constructed several mono- and bicistronic antisense recombinants against HBx and c-myc genes to regulate their expression as well as transactivation function in a human hepatoma cell line. A dose-dependent inhibition in the expression levels of HBx and c-Myc was observed with monocistronic constructs. Likewise, the bicistronic recombinants also blocked the expression as well as transactivation functions of cognate genes with equal efficacy. Further, expression of the constituent genes from the X-myc transgene could also be inhibited by these antisense constructs in cell culture. Thus, our study points towards clinical implications of antisense regulation of tumor-promoting genes in the management of HCC.

  5. c-Myc activates multiple metabolic networks to generate substrates for cell-cycle entry.

    Energy Technology Data Exchange (ETDEWEB)

    Morrish, Fionnuala M.; Isern, Nancy; Sadilek, Martin; Jeffrey, Mark; Hockenbery, David M.

    2009-05-18

    Cell proliferation requires the coordinated activity of cytosolic and mitochondrial metabolic pathways to provide ATP and building blocks for DNA, RNA, and protein synthesis. Many metabolic pathway genes are targets of the c-myc oncogene and cell cycle regulator. However, the contribution of c-Myc to the activation of cytosolic and mitochondrial metabolic networks during cell cycle entry is unknown. Here, we report the metabolic fates of [U-13C] glucose in serum-stimulated myc-/- and myc+/+ fibroblasts by 13C isotopomer NMR analysis. We demonstrate that endogenous c-myc increased 13C-labeling of ribose sugars, purines, and amino acids, indicating partitioning of glucose carbons into C1/folate and pentose phosphate pathways, and increased tricarboxylic acid cycle turnover at the expense of anaplerotic flux. Myc expression also increased global O-linked GlcNAc protein modification, and inhibition of hexosamine biosynthesis selectively reduced growth of Myc-expressing cells, suggesting its importance in Myc-induced proliferation. These data reveal a central organizing role for the Myc oncogene in the metabolism of cycling cells. The pervasive deregulation of this oncogene in human cancers may be explained by its role in directing metabolic networks required for cell proliferation.

  6. Can c-myc amplification reliably discriminate postradiation from primary angiosarcoma of the breast?

    Science.gov (United States)

    Laé, M; Lebel, A; Hamel-Viard, F; Asselain, B; Trassard, M; Sastre, X; Kirova, Y M

    2015-05-01

    Breast angiosarcomas are rare vascular malignancies that arise secondary to irradiation or de novo as primary tumours. The aim of this study is to know whether c-myc amplification can reliably discriminate these two entities. Forty-seven patients treated for breast angiosarcomas were studied. Thirty-two patients were diagnosed with postradiation angiosarcomas after breast cancer treatment and 15 patients with primary angiosarcomas. Interphase fluorescence in situ hybridization (FISH) was performed by hybridization of probes covering C-MYC (chromosome 8q24.21) and CEP8 on tissue sections. Amplification (5- to 20-fold) of the c-myc oncogene was found in all breast radiation-induced angiosarcomas (32 tumours) but in none of the 15 primary angiosarcomas except one (7%). This study reinforces that there are true pathogenetic differences between the two types of breast angiosarcomas which are morphologically indistinguishable. These data point the pathways preferentially involved in the pathogenesis of post radiation angiosarcomas of the breast and may provide the basis for an additional targeted therapy. Copyright © 2015 Société française de radiothérapie oncologique (SFRO). Published by Elsevier SAS. All rights reserved.

  7. c-Myc activates multiple metabolic networks to generate substrates for cell-cycle entry.

    Science.gov (United States)

    Morrish, F; Isern, N; Sadilek, M; Jeffrey, M; Hockenbery, D M

    2009-07-09

    Cell proliferation requires the coordinated activity of cytosolic and mitochondrial metabolic pathways to provide ATP and building blocks for DNA, RNA and protein synthesis. Many metabolic pathway genes are targets of the c-myc oncogene and cell-cycle regulator. However, the contribution of c-Myc to the activation of cytosolic and mitochondrial metabolic networks during cell-cycle entry is unknown. Here, we report the metabolic fates of [U-(13)C] glucose in serum-stimulated myc(-/-) and myc(+/+) fibroblasts by (13)C isotopomer NMR analysis. We demonstrate that endogenous c-myc increased (13)C labeling of ribose sugars, purines and amino acids, indicating partitioning of glucose carbons into C1/folate and pentose phosphate pathways, and increased tricarboxylic acid cycle turnover at the expense of anaplerotic flux. Myc expression also increased global O-linked N-acetylglucosamine protein modification, and inhibition of hexosamine biosynthesis selectively reduced growth of Myc-expressing cells, suggesting its importance in Myc-induced proliferation. These data reveal a central organizing function for the Myc oncogene in the metabolism of cycling cells. The pervasive deregulation of this oncogene in human cancers may be explained by its function in directing metabolic networks required for cell proliferation.

  8. Angiotensin II reduces cardiac AdipoR1 expression through AT1 receptor/ROS/ERK1/2/c-Myc pathway.

    Directory of Open Access Journals (Sweden)

    Li Li

    Full Text Available Adiponectin, an abundant adipose tissue-derived protein, exerts protective effect against cardiovascular disease. Adiponectin receptors (AdipoR1 and AdipoR2 mediate the beneficial effects of adiponectin on the cardiovascular system. However, the alteration of AdipoRs in cardiac remodeling is not fully elucidated. Here, we investigated the effect of angiotensin II (AngII on cardiac AdipoRs expression and explored the possible molecular mechanism. AngII infusion into rats induced cardiac hypertrophy, reduced AdipoR1 but not AdipoR2 expression, and attenuated the phosphorylations of adenosine monophosphate-activated protein kinase and acetyl coenzyme A carboxylase, and those effects were all reversed by losartan, an AngII type 1 (AT1 receptor blocker. AngII reduced expression of AdipoR1 mRNA and protein in cultured neonatal rat cardiomyocytes, which was abolished by losartan, but not by PD123319, an AT2 receptor antagonist. The antioxidants including reactive oxygen species (ROS scavenger NAC, NADPH oxidase inhibitor apocynin, Nox2 inhibitor peptide gp91 ds-tat, and mitochondrial electron transport chain complex I inhibitor rotenone attenuated AngII-induced production of ROS and phosphorylation of extracellular signal-regulated kinase (ERK 1/2. AngII-reduced AdipoR1 expression was reversed by pretreatment with NAC, apocynin, gp91 ds-tat, rotenone, and an ERK1/2 inhibitor PD98059. Chromatin immunoprecipitation assay demonstrated that AngII provoked the recruitment of c-Myc onto the promoter region of AdipoR1, which was attenuated by PD98059. Moreover, AngII-induced DNA binding activity of c-Myc was inhibited by losartan, NAC, apocynin, gp91 ds-tat, rotenone, and PD98059. c-Myc small interfering RNA abolished the inhibitory effect of AngII on AdipoR1 expression. Our results suggest that AngII inhibits cardiac AdipoR1 expression in vivo and in vitro and AT1 receptor/ROS/ERK1/2/c-Myc pathway is required for the downregulation of AdipoR1 induced by AngII.

  9. qPCR based mRNA quality score show intact mRNA after heat stabilization

    Directory of Open Access Journals (Sweden)

    Oskar Karlsson

    2016-03-01

    Full Text Available Analysis of multiple analytes from biological samples can be challenging as different analytes require different preservation measures. Heat induced enzymatic inactivation is an efficient way to preserve proteins and their modifications in biological samples but RNA quality, as measured by RIN value, has been a concern in such samples. Here, we investigate the effect of heat stabilization compared with standard snap freezing on RNA quality using two RNA extraction protocols, QiaZol with and without urea pre-solubilization, and two RNA quality measurements: RIN value, as defined by the Agilent Bioanalyzer, and an alternative qPCR based method. DNA extraction from heat stabilized brain samples was also examined. The snap frozen samples had RIN values about 1 unit higher than heat stabilized samples for the direct QiaZol extraction but equal with stabilized samples using urea pre-solubilization. qPCR based RNA quality measurement showed no difference in quality between snap frozen and heat inactivated samples. The probable explanation for this discrepancy is that the RIN value is an indirect measure based on rRNA, while the qPCR score is based on actual measurement of mRNA quality. The DNA yield from heat stabilized brain tissue samples was significantly increased, compared to the snap frozen tissue, without any effects on purity or quality. Hence, heat stabilization of tissues opens up the possibility for a two step preservation protocol, where proteins and their modifications can be preserved in the first heat based step, while in a second step, using standard RNA preservation strategies, mRNA be preserved. This collection strategy will enable biobanking of samples where the ultimate analysis is not determined without loss of sample quality.

  10. Downregulation of c-Myc is involved in TLR3-mediated tumor death of neuroblastoma xenografts.

    Science.gov (United States)

    Lin, Li-Ling; Huang, Chao-Cheng; Wu, Chia-Ling; Wu, Min-Tsui; Hsu, Wen-Ming; Chuang, Jiin-Haur

    2016-07-01

    Neuroblastoma (NB) is the deadliest pediatric solid tumor due to its pleomorphic molecular characteristics. In the innate immune system, toll-like receptor 3 (TLR3) recognizes viral double-stranded RNAs to initiate immune signaling. Positive TLR3 expression indicates a favorable prognosis in NB patients, and is associated with MYCN-non-amplified. However, TLR3-mediated innate immune responses remain elusive in NB. In this study, we attempted to dissect the molecular mechanism underlying TLR3-agonist polyinosinic-polycytidylic acid [poly(I:C)] treatment in NB in vivo. We established NB xenograft models in non-obese diabetic/severe combined immunodeficiency (NOD/SCID) mice with MYCN-amplified SK-N-DZ (DZ) cells or MYCN-non-amplified SK-N-AS (AS) cells. Poly(I:C) treatment led to significant tumor regression in AS xenografts, but not in DZ xenografts. Through immunohistochemical analysis, significant suppression of tumor proliferation, downregulation of c-Myc expression, and upregulation of TLR3 expression were found in the treatment group. Poly(I:C) inducing activation of TLR3/IRF3-mediated innate immunity associated with downregulation of c-Myc can be found in MYCN-non-amplified SK-N-AS cells, but not in MYCN-amplified BE(2)-M17 cells. Knockdown of TLR3 disturbed poly(I:C)-induced suppression of c-Myc and upregulation of p-IRF3 in AS cells. Furthermore, poly(I:C) treatment upregulated active NF-κB, mitochondrial antioxidant manganese superoxide dismutase and 8-hydroxydeoxyguanosine, which works with reactive oxygen species (ROS) generation and DNA damage. Upregulation of active caspase 3 and cleaved poly [ADP-ribose] polymerase 1 were found in poly(I:C)-treated AS xenografts, which indicates the induction of apoptosis. Thus, our results suggest that c-Myc overexpression may increase sensitivity to poly(I:C)-induced tumor growth arrest and ROS-mediated apoptosis in NB. This study demonstrates that c-Myc protein expression has an important role in TLR3-induced innate

  11. An Epigenetic Pathway Regulates Sensitivity of Breast Cancer Cells to HER2 Inhibition via FOXO/c-Myc Axis

    Science.gov (United States)

    Matkar, Smita; Sharma, Paras; Gao, Shubin; Gurung, Buddha; Katona, Bryson W; Liao, Jennifer; Muhammad, Abdul Bari; Kong, Xiang-Cheng; Wang, Lei; Jin, Guanghui; Dang, Chi; Hua, Xianxin

    2016-01-01

    SUMMARY Human epidermal growth factor receptor 2 (HER2) is upregulated in a subset of human breast cancers. However, the cancer cells often quickly develop an adaptive response to HER2 kinase inhibitors. We found that an epigenetic pathway involving MLL2 is crucial for growth of HER2+ cells and MLL2 reduces sensitivity of the cancer cells to a HER2 inhibitor, Lapatinib. Lapatinib-induced FOXO transcription factors, normally tumor-suppressing, paradoxically upregulate c-Myc epigenetically, in concert with a cascade of MLL2-associating epigenetic regulators, to dampen sensitivity of the cancer cells to Lapatinib. An epigenetic inhibitor suppressing c-Myc synergizes with Lapatinib to suppress cancer growth in vivo, partly by repressing the FOXO/c-Myc axis, unraveling an epigenetically regulated FOXO/c-Myc axis as a potential target to improve therapy. PMID:26461093

  12. Non-transmissible Sendai virus vector encoding c-myc suppressor FBP-interacting repressor for cancer therapy.

    Science.gov (United States)

    Matsushita, Kazuyuki; Shimada, Hideaki; Ueda, Yasuji; Inoue, Makoto; Hasegawa, Mamoru; Tomonaga, Takeshi; Matsubara, Hisahiro; Nomura, Fumio

    2014-04-21

    To investigate a novel therapeutic strategy to target and suppress c-myc in human cancers using far up stream element (FUSE)-binding protein-interacting repressor (FIR). Endogenous c-Myc suppression and apoptosis induction by a transient FIR-expressing vector was examined in vivo via a HA-tagged FIR (HA-FIR) expression vector. A fusion gene-deficient, non-transmissible, Sendai virus (SeV) vector encoding FIR cDNA, SeV/dF/FIR, was prepared. SeV/dF/FIR was examined for its gene transduction efficiency, viral dose dependency of antitumor effect and apoptosis induction in HeLa (cervical squamous cell carcinoma) cells and SW480 (colon adenocarcinoma) cells. Antitumor efficacy in a mouse xenograft model was also examined. The molecular mechanism of the anti-tumor effect and c-Myc suppression by SeV/dF/FIR was examined using Spliceostatin A (SSA), a SAP155 inhibitor, or SAP155 siRNA which induce c-Myc by increasing FIR∆exon2 in HeLa cells. FIR was found to repress c-myc transcription and in turn the overexpression of FIR drove apoptosis through c-myc suppression. Thus, FIR expressing vectors are potentially applicable for cancer therapy. FIR is alternatively spliced by SAP155 in cancer cells lacking the transcriptional repression domain within exon 2 (FIR∆exon2), counteracting FIR for c-Myc protein expression. Furthermore, FIR forms a complex with SAP155 and inhibits mutual well-established functions. Thus, both the valuable effects and side effects of exogenous FIR stimuli should be tested for future clinical application. SeV/dF/FIR, a cytoplasmic RNA virus, was successfully prepared and showed highly efficient gene transduction in in vivo experiments. Furthermore, in nude mouse tumor xenograft models, SeV/dF/FIR displayed high antitumor efficiency against human cancer cells. SeV/dF/FIR suppressed SSA-activated c-Myc. SAP155 siRNA, potentially produces FIR∆exon2, and led to c-Myc overexpression with phosphorylation at Ser62. HA-FIR suppressed endogenous c-Myc

  13. HDAC3 regulates stability of estrogen receptor α mRNA

    Energy Technology Data Exchange (ETDEWEB)

    Oie, Shohei; Matsuzaki, Kazuya; Yokoyama, Wataru; Murayama, Akiko; Yanagisawa, Junn, E-mail: junny@agbi.tsukuba.ac.jp

    2013-03-08

    Highlights: ► HDAC inhibitors decrease the stability of ERα mRNA in MCF-7 cells. ► HDAC3 is involved in maintaining ERα mRNA stability in MCF-7 cells. ► ERα mRNA instability by knockdown of HDAC3 reduces the estrogen-dependent proliferation of ERα-positive MCF-7 cells. ► HDAC3 specific inhibitor will be one of new drugs for ERα-positive breast cancers. -- Abstract: Estrogen receptor alpha (ERα) expression is a risk factor for breast cancer. HDAC inhibitors have been demonstrated to down-regulate ERα expression in ERα-positive breast cancer cell lines, but the molecular mechanisms are poorly understood. Here, we showed that HDAC inhibitors decrease the stability of ERα mRNA, and that knockdown of HDAC3 decreases the stability of ERα mRNA and suppresses estrogen-dependent proliferation of ERα-positive MCF-7 breast cancer cells. In the Oncomine database, expression levels of HDAC3 in ERα-positive tumors are higher than those in ERα-negative tumors, thus suggesting that HDAC3 is necessary for ERα mRNA stability, and is involved in the estrogen-dependent proliferation of ERα-positive tumors.

  14. Prognostic Value of Beta-Tubulin-3 and c-Myc in Muscle Invasive Urothelial Carcinoma of the Bladder

    Science.gov (United States)

    Massari, Francesco; Bria, Emilio; Ciccarese, Chiara; Munari, Enrico; Modena, Alessandra; Zambonin, Valentina; Sperduti, Isabella; Artibani, Walter; Cheng, Liang; Martignoni, Guido; Tortora, Giampaolo; Brunelli, Matteo

    2015-01-01

    Background To date, putative prognostic biomarkers have shown limited utility from the clinical perspective for bladder urothelial carcinoma. Herein, the expression of beta-tubulin-3 and c-Myc was evaluated to determine their prognostic potential. Methods In formalin fixed-paraffin embedded blocks, immunohistochemical expression of c-Myc and beta-tubulin-3 was evaluated. H score ranging from 0 to 300 was obtained by multiplying the percentage of positive cells by intensity (0–3); c-Myc and beta-tubulin-3 expression was defined: 0: negative, 1: weakly positive, 2: strongly positive. Results beta-tubulin-3 and c-Myc immunoexpression was available for 46 cases. At the univariate analysis, node-involvement, beta-tubulin-3 and c-Myc overexpression discriminate shorter DFS (HR 2.19, p = 0.043; HR 3.10, p = 0.24 and HR 3.05, p = 0.011, respectively); 2-yrs DFS log-rank analysis according to low versus high level of immunoexpression were statistically significant; beta-tubulin-3, 53% low vs 12.7% high (p = value 0.02) and c-Myc 28 low vs 8 high (p-value 0.007). Patients displaying negative beta-tubulin-3/c-Myc had statistically significant better 2-yrs DFS than those with mixed expression or double positivity (54.5% versus 18.7% versus 0%, log-rank p = 0.006). Conclusions c-Myc and beta-tubulin-3 show improvement for prognostic risk stratification in patients with muscle invasive bladder urothelial carcinoma. These molecular pathways may also be candidate to improve predictiveness to targeted therapies. PMID:26046361

  15. Prognostic Value of Beta-Tubulin-3 and c-Myc in Muscle Invasive Urothelial Carcinoma of the Bladder.

    Directory of Open Access Journals (Sweden)

    Francesco Massari

    Full Text Available To date, putative prognostic biomarkers have shown limited utility from the clinical perspective for bladder urothelial carcinoma. Herein, the expression of beta-tubulin-3 and c-Myc was evaluated to determine their prognostic potential.In formalin fixed-paraffin embedded blocks, immunohistochemical expression of c-Myc and beta-tubulin-3 was evaluated. H score ranging from 0 to 300 was obtained by multiplying the percentage of positive cells by intensity (0-3; c-Myc and beta-tubulin-3 expression was defined: 0: negative, 1: weakly positive, 2: strongly positive.beta-tubulin-3 and c-Myc immunoexpression was available for 46 cases. At the univariate analysis, node-involvement, beta-tubulin-3 and c-Myc overexpression discriminate shorter DFS (HR 2.19, p = 0.043; HR 3.10, p = 0.24 and HR 3.05, p = 0.011, respectively; 2-yrs DFS log-rank analysis according to low versus high level of immunoexpression were statistically significant; beta-tubulin-3, 53% low vs 12.7% high (p = value 0.02 and c-Myc 28 low vs 8 high (p-value 0.007. Patients displaying negative beta-tubulin-3/c-Myc had statistically significant better 2-yrs DFS than those with mixed expression or double positivity (54.5% versus 18.7% versus 0%, log-rank p = 0.006.c-Myc and beta-tubulin-3 show improvement for prognostic risk stratification in patients with muscle invasive bladder urothelial carcinoma. These molecular pathways may also be candidate to improve predictiveness to targeted therapies.

  16. Absence of missense mutations in activated c-myc genes in avian leukosis virus-induced B-cell lymphomas

    Energy Technology Data Exchange (ETDEWEB)

    Hahn, M.; Hayward, W.S.

    1988-06-01

    The authors determined the nucleotide sequences of two independent DNA clones which contained the activated c-myc genes from avian leukosis virus-induced B-cell lymphomas. Neither of these c-myce genes contained missense mutations. This strongly supports the notion that the c-myc photo-oncogene in avian leukosis virus-induced B-cell lymphomas can be oncogenically activated by altered expression of the gene without a change in the primary structure of the gene product.

  17. Evolutionary history of c-myc in teleosts and characterization of the duplicated c-myca genes in goldfish embryos.

    Science.gov (United States)

    Marandel, Lucie; Labbe, Catherine; Bobe, Julien; Le Bail, Pierre-Yves

    2012-02-01

    c-Myc plays an important role during embryogenesis in mammals, but little is known about its function during embryonic development in teleosts. In addition, the evolutionary history of c-myc gene in teleosts remains unclear, and depending on the species, a variable number of gene duplicates exist in teleosts. To gain new insight into c-myc genes in teleosts, the present study was designed to clarify the evolutionary history of c-myc gene(s) in teleosts and to subsequently characterize DNA methylation and early embryonic expression patterns in a cyprinid fish. Our results show that a duplication of c-myc gene occurred before or around the teleost radiation, as a result of the teleost-specific whole genome duplication giving rise to c-myca and c-mycb in teleosts and was followed by a loss of the c-mycb gene in the Gasterosteiforms and Tetraodontiforms. Our data also demonstrate that both c-myc genes previously identified in carp and goldfish are co-orthologs of the zebrafish c-myca. These results indicate the presence of additional c-myca duplication in Cyprininae. We were able to identify differences between the expression patterns of the two goldfish c-myca genes in oocytes and early embryos. These differences suggest a partial sub-functionalization of c-myca genes after duplication. Despite differences in transcription patterns, both of the c-myca genes displayed similar DNA methylation patterns during early development and in gametes. Together, our results clarify the evolutionary history of the c-myc gene in teleosts and provide new insight into the involvement of c-myc in early embryonic development in cyprinids. Copyright © 2011 Wiley Periodicals, Inc.

  18. Frequent co-amplification and co-operation between C-MYC and PVT1 oncogenes promote malignant pleural mesothelioma

    Science.gov (United States)

    Riquelme, Erick; Suraokar, Milind B.; Rodriguez, Jaime; Mino, Barbara; Lin, Heather Y.; Rice, David C.; Tsao, Anne; Wistuba, Ignacio I.

    2014-01-01

    Introduction Malignant pleural mesothelioma (MPM) is a deadly disease with poor prognosis and few treatment options. We characterized and elucidate the roles of C-MYC and PVT1 involved in the pathogenesis of MPM. Methods We used siRNA-mediated knockdown in MPM cell lines to determine the effect of C-MYC and PVT1 abrogation on MPM cells undergoing apoptosis, proliferation, and cisplatin sensitivity. We also characterized the expression of microRNAs (miRNAs) spanning the PVT1 region in MPM cell lines. Copy number analysis was measured by quantitative PCR and fluorescence in situ hybridization. Results Copy number analysis revealed copy number gains (CNGs) in chromosomal region 8q24 in six of twelve MPM cell lines. MicroRNA analysis showed high miR-1204 expression in MSTO-211H cell lines with ≥4 copies of PVT1. Knockdown by siRNA showed increased PARP-C levels in MSTO-211H transfected with siPVT1 but not in cells transfected with siC-MYC. C-MYC and PVT1 knockdown reduced cell proliferation and increased sensitivity to cisplatin. Analysis of the expression of apoptosis-related genes in the MSTO-211H cell line suggested that C-MYC maintains a balance between pro-apoptotic and anti-apoptotic gene expression, whereas PVT1 and to a lesser extent miR-1204, upregulate pro-apoptotic genes and downregulate anti-apoptotic genes. FISH analysis of MPM tumor specimens showed a high frequency of both CNGs (11/75) and trisomy (three copies; 11/75) for the C-MYC locus. Conclusion Our results suggest that C-MYC and PVT1 copy number gain promotes a malignant phenotype of MPM, with C-MYC CNG stimulating cell proliferation and PVT1 both stimulating proliferation and inhibiting apoptosis. PMID:24926545

  19. Activated α2-Macroglobulin Regulates Transcriptional Activation of c-MYC Target Genes through Cell Surface GRP78 Protein.

    Science.gov (United States)

    Gopal, Udhayakumar; Gonzalez-Gronow, Mario; Pizzo, Salvatore Vincent

    2016-05-13

    Activated α2-macroglobulin (α2M*) signals predominantly through cell surface GRP78 (CS-GRP78) to promote proliferation and survival of cancer cells; however, the molecular mechanism remains obscure. c-MYC is an essential transcriptional regulator that controls cell proliferation. We hypothesize that α2M*/CS-GRP78-evoked key signaling events are required for transcriptional activation of c-MYC target genes. Activation of CS-GRP78 by α2M* requires ligation of the GRP78 primary amino acid sequence (Leu(98)-Leu(115)). After stimulation with α2M*, CS-GRP78 signaling activates 3-phosphoinositide-dependent protein kinase-1 (PDK1) to induce phosphorylation of PLK1, which in turn induces c-MYC transcription. We demonstrate that PLK1 binds directly to c-MYC and promotes its transcriptional activity by phosphorylating Ser(62) Moreover, activated c-MYC is recruited to the E-boxes of target genes FOSL1 and ID2 by phosphorylating histone H3 at Ser(10) In addition, targeting the carboxyl-terminal domain of CS-GRP78 with a mAb suppresses transcriptional activation of c-MYC target genes and impairs cell proliferation. This work demonstrates that α2M*/CS-GRP78 acts as an upstream regulator of the PDK1/PLK1 signaling axis to modulate c-MYC transcription and its target genes, suggesting a therapeutic strategy for targeting c-MYC-associated malignant progression. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

  20. c-Myc Antagonises the Transcriptional Activity of the Androgen Receptor in Prostate Cancer Affecting Key Gene Networks.

    Science.gov (United States)

    Barfeld, Stefan J; Urbanucci, Alfonso; Itkonen, Harri M; Fazli, Ladan; Hicks, Jessica L; Thiede, Bernd; Rennie, Paul S; Yegnasubramanian, Srinivasan; DeMarzo, Angelo M; Mills, Ian G

    2017-04-01

    Prostate cancer (PCa) is the most common non-cutaneous cancer in men. The androgen receptor (AR), a ligand-activated transcription factor, constitutes the main drug target for advanced cases of the disease. However, a variety of other transcription factors and signaling networks have been shown to be altered in patients and to influence AR activity. Amongst these, the oncogenic transcription factor c-Myc has been studied extensively in multiple malignancies and elevated protein levels of c-Myc are commonly observed in PCa. Its impact on AR activity, however, remains elusive. In this study, we assessed the impact of c-Myc overexpression on AR activity and transcriptional output in a PCa cell line model and validated the antagonistic effect of c-MYC on AR-targets in patient samples. We found that c-Myc overexpression partially reprogrammed AR chromatin occupancy and was associated with altered histone marks distribution, most notably H3K4me1 and H3K27me3. We found c-Myc and the AR co-occupy a substantial number of binding sites and these exhibited enhancer-like characteristics. Interestingly, c-Myc overexpression antagonised clinically relevant AR target genes. Therefore, as an example, we validated the antagonistic relationship between c-Myc and two AR target genes, KLK3 (alias PSA, prostate specific antigen), and Glycine N-Methyltransferase (GNMT), in patient samples. Our findings provide unbiased evidence that MYC overexpression deregulates the AR transcriptional program, which is thought to be a driving force in PCa. Crown Copyright © 2017. Published by Elsevier B.V. All rights reserved.

  1. Activated α2-Macroglobulin Regulates Transcriptional Activation of c-MYC Target Genes through Cell Surface GRP78 Protein*

    Science.gov (United States)

    Gopal, Udhayakumar; Gonzalez-Gronow, Mario; Pizzo, Salvatore Vincent

    2016-01-01

    Activated α2-macroglobulin (α2M*) signals predominantly through cell surface GRP78 (CS-GRP78) to promote proliferation and survival of cancer cells; however, the molecular mechanism remains obscure. c-MYC is an essential transcriptional regulator that controls cell proliferation. We hypothesize that α2M*/CS-GRP78-evoked key signaling events are required for transcriptional activation of c-MYC target genes. Activation of CS-GRP78 by α2M* requires ligation of the GRP78 primary amino acid sequence (Leu98–Leu115). After stimulation with α2M*, CS-GRP78 signaling activates 3-phosphoinositide-dependent protein kinase-1 (PDK1) to induce phosphorylation of PLK1, which in turn induces c-MYC transcription. We demonstrate that PLK1 binds directly to c-MYC and promotes its transcriptional activity by phosphorylating Ser62. Moreover, activated c-MYC is recruited to the E-boxes of target genes FOSL1 and ID2 by phosphorylating histone H3 at Ser10. In addition, targeting the carboxyl-terminal domain of CS-GRP78 with a mAb suppresses transcriptional activation of c-MYC target genes and impairs cell proliferation. This work demonstrates that α2M*/CS-GRP78 acts as an upstream regulator of the PDK1/PLK1 signaling axis to modulate c-MYC transcription and its target genes, suggesting a therapeutic strategy for targeting c-MYC-associated malignant progression. PMID:27002159

  2. Coordinate increase of telomerase activity and c-Myc expression in Helicobacter pylori-associated gastric diseases

    Institute of Scientific and Technical Information of China (English)

    Guo-Xin Zhang; Yan-Hong Gu; Zhi-Quan Zhao; Shun-Fu Xu; Hong-Ji Zhang; Hong-Di Wang; Bo Hao

    2004-01-01

    AIM: To detect the telomerase activity and c-Myc expression in gastric diseases and to examine the relation between these values and Helicobacter pylori (H pylori) as a risk factor for gastric cancer.METHODS: One hundred and seventy-one gastric samples were studied to detect telomerase activity using a telomerase polymerase chain reaction enzyme linked immunosorbent assay (PCR-ELTSA), and c-Myc expression using immunohistochemistry.RESULTS: The telomerase activity and c-Myc expression were higher in cancers (87.69% and 61.54%) than in noncancerous tissues. They were higher in chronic atrophic gastritis with severe intestinal metaplasia (52.38% and 47.62%) than in chronic atrophic gastritis with mild intestinal metaplasia (13.33% and 16.67%). Tn chronic atrophic gastritis with severe intestinal metaplasia, the telomerase activity and c-Myc expression were higher in cases with -H pylori infection (67.86% and 67.86%) than in those without infection (21.43%and 7.14%). c-Myc expression was higher in gastric cancer with H pylori infection (77.27%) than in that without infection (28.57%). The telomerase activity and c-Nyc expression were coordinately up-regulated in H pylori infected gastric cancer and chronic atrophic gastritis with severe intestinal metaplasia.CONCLUSION: H pylori infection may influence both telomerase activity and c-Myc expression in gastric diseases,especially in chronic atrophic gastritis.

  3. Expression of C-myc and β-catenin and their correlation in triple negative breast cancer.

    Science.gov (United States)

    Wang, Jiankui; Li, Mei; Chen, Dedian; Nie, Jianyun; Xi, Yan; Yang, Xiaojuan; Chen, Yun; Yang, Zhuanqing

    2017-09-08

    The present study was planned to study the expression of C-myc and β- catenin in triple negative breast cancer (TNBC) tissue. Furthermore, their relations to clinical features of the tumor and the survival prognosis were also studied. Additionally, correlation was evaluated between the expression of C-myc and β- catenin to provide the theoretical basis for the targeted therapy of TNBC. 60 cases of patients diagnosed with TNBC for the first time were selected for the study. The immumo-histochemical staining was employed to detect the positive expression rates of C-myc and β-catenin in cancer tissues and normal mammary tissues 3 cm away from the carcinoma. Fluorescence in situ hybridization (FISH) was used to test the gene amplification of C-myc in order to analyze the relation between C-myc and the protein expression of β-catenin. Further, kept the median follow-up time to 25.0 months in order to compare the survival prognosis. The positive expression rates of C-myc and β-catenin in cancer tissues were significantly higher than those in precancerous normal tissues (Pcorrelated with clinical features of cancer and the survival prognosis.

  4. Mechanisms of transcriptional activation of the stimulator of interferon genes by transcription factors CREB and c-Myc.

    Science.gov (United States)

    Wang, Yan-Yan; Jin, Rui; Zhou, Guo-Ping; Xu, Hua-Guo

    2016-12-20

    Stimulator of interferon genes (STING) plays an important role in host defense, autoimmune disease, osteoclast differentiation and anti-tumor response. Although many downstream targets have been studied in depth, the regulation of STING gene expression remains largely unknown. Here we demonstrate that transcription factors CREB and c-Myc maintain the transcriptional activity of STING. By 5'-rapid amplification of cDNA ends analysis, we identified the transcriptional start site (TSS) of STING. We illustrated that the region -124/+1 relative to TSS was sufficient for full promoter activity by a series of 5' deletion promoter constructs. Transcriptional activity of the STING minimal promoter was dependent on CREB and c-Myc binding motifs and was abolished after mutation of these two DNA elements. Chromatin immunoprecipitation assays demonstrated that transcription factors CREB and c-Myc bind to STING promoter in vivo. Overexpression of CREB and c-Myc increased the STING promoter activity. Meanwhile, knocking-down of CREB and c-Myc by a small interfering RNA (siRNA) strategy markedly reduced endogenous STING expression. In summary, these results demonstrated that transcription factors CREB and c-Myc are involved in the regulation of STING transcription.

  5. C-Myc negatively controls the tumor suppressor PTEN by upregulating miR-26a in glioblastoma multiforme cells

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Pin; Nie, Quanmin; Lan, Jin; Ge, Jianwei [Department of Neurosurgery, Ren Ji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200127 (China); Qiu, Yongming, E-mail: qiuzhoub@hotmail.com [Department of Neurosurgery, Ren Ji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200127 (China); Shanghai Institute of Head Trauma, Shanghai 200127 (China); Mao, Qing, E-mail: maoq@netease.com [Department of Neurosurgery, Ren Ji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200127 (China); Shanghai Institute of Head Trauma, Shanghai 200127 (China)

    2013-11-08

    Highlights: •The c-Myc oncogene directly upregulates miR-26a expression in GBM cells. •ChIP assays demonstrate that c-Myc interacts with the miR-26a promoter. •Luciferase reporter assays show that PTEN is a specific target of miR-26a. •C-Myc–miR-26a suppression of PTEN may regulate the PTEN/AKT pathway. •Overexpression of c-Myc enhances the proliferative capacity of GBM cells. -- Abstract: The c-Myc oncogene is amplified in many tumor types. It is an important regulator of cell proliferation and has been linked to altered miRNA expression, suggesting that c-Myc-regulated miRNAs might contribute to tumor progression. Although miR-26a has been reported to be upregulated in glioblastoma multiforme (GBM), the mechanism has not been established. We have shown that ectopic expression of miR-26a influenced cell proliferation by targeting PTEN, a tumor suppressor gene that is inactivated in many common malignancies, including GBM. Our findings suggest that c-Myc modulates genes associated with oncogenesis in GBM through deregulation of miRNAs via the c-Myc–miR-26a–PTEN signaling pathway. This may be of clinical relevance.

  6. BAF53 Forms Distinct Nuclear Complexes and Functions as a Critical c-Myc-Interacting Nuclear Cofactor for Oncogenic Transformation

    Science.gov (United States)

    Park, Jeonghyeon; Wood, Marcelo A.; Cole, Michael D.

    2002-01-01

    The c-Myc oncoprotein functions as a transcription factor that can transform normal cells into tumor cells, as well as playing a direct role in normal cell proliferation. The c-Myc protein transactivates cellular promoters by recruiting nuclear cofactors to chromosomal sites through an N-terminal transactivation domain. We have previously reported the identification and functional characterization of four different c-Myc cofactors: TRRAP, hGCN5, TIP49, and TIP48. Here we present the identification and characterization of the actin-related protein BAF53 as a c-Myc-interacting nuclear cofactor that forms distinct nuclear complexes. In addition to the human SWI/SNF-related BAF complex, BAF53 forms a complex with TIP49 and TIP48 and a separate biochemically distinct complex containing TRRAP and a histone acetyltransferase which does not contain TIP60. Using deletion mutants of BAF53, we show that BAF53 is critical for c-Myc oncogenic activity. Our results indicate that BAF53 plays a functional role in c-Myc-interacting nuclear complexes. PMID:11839798

  7. Transient activation of c-MYC expression is critical for efficient platelet generation from human induced pluripotent stem cells.

    Science.gov (United States)

    Takayama, Naoya; Nishimura, Satoshi; Nakamura, Sou; Shimizu, Takafumi; Ohnishi, Ryoko; Endo, Hiroshi; Yamaguchi, Tomoyuki; Otsu, Makoto; Nishimura, Ken; Nakanishi, Mahito; Sawaguchi, Akira; Nagai, Ryozo; Takahashi, Kazutoshi; Yamanaka, Shinya; Nakauchi, Hiromitsu; Eto, Koji

    2010-12-20

    Human (h) induced pluripotent stem cells (iPSCs) are a potentially abundant source of blood cells, but how best to select iPSC clones suitable for this purpose from among the many clones that can be simultaneously established from an identical source is not clear. Using an in vitro culture system yielding a hematopoietic niche that concentrates hematopoietic progenitors, we show that the pattern of c-MYC reactivation after reprogramming influences platelet generation from hiPSCs. During differentiation, reduction of c-MYC expression after initial reactivation of c-MYC expression in selected hiPSC clones was associated with more efficient in vitro generation of CD41a(+)CD42b(+) platelets. This effect was recapitulated in virus integration-free hiPSCs using a doxycycline-controlled c-MYC expression vector. In vivo imaging revealed that these CD42b(+) platelets were present in thrombi after laser-induced vessel wall injury. In contrast, sustained and excessive c-MYC expression in megakaryocytes was accompanied by increased p14 (ARF) and p16 (INK4A) expression, decreased GATA1 expression, and impaired production of functional platelets. These findings suggest that the pattern of c-MYC expression, particularly its later decline, is key to producing functional platelets from selected iPSC clones.

  8. Expression of Wnt-1,beta-catenin and c-myc in Ovarian Epithelial Tumor and Its Implication

    Institute of Scientific and Technical Information of China (English)

    LIN Xiao; HU Zhuo-ying

    2008-01-01

    Objective:To investigate the expression of Wnt-1, beta-catenin and c-myc in normal ovarian epithelial cell and malignant ovarian epithelial tumor. Methods:Immunohistochemical staining with SP method was conducted to identify the expression of Wnt-1,beta-catenin and c-myc in 18 samples of normal epithelial tissue and 34 cases of malignant epithelial tumor of ovary. Results:The expression rate of Wnt-1 and c-myc in malignant epithelial tumors was higher than those in normal epithelial cell(P<0.05).The abnormal expression rate of beta-catenin in malignant ovarian epithelial tumors was higher than that in normal epithelial cell(P<0.05).A significant positive correlation was found between Wnt-1, beta-catenin and c-myc in malignant ovarian epithelial tumor(P<0.05).A significant difierence of expressions of Beta-catenin and C-myc was found between serous and mutinous tumors (P<0.05). Conclusion:The abnormal expression of Wnt-1,beta-catenin and c-myc might indicate the malignant transformation in ovarian epithelial tumors.

  9. Major role for mRNA stability in shaping the kinetics of gene induction

    Directory of Open Access Journals (Sweden)

    Zeller Karen I

    2010-04-01

    Full Text Available Abstract Background mRNA levels in cells are determined by the relative rates of RNA production and degradation. Yet, to date, most analyses of gene expression profiles were focused on mechanisms which regulate transcription, while the role of mRNA stability in modulating transcriptional networks was to a large extent overlooked. In particular, kinetic waves in transcriptional responses are usually interpreted as resulting from sequential activation of transcription factors. Results In this study, we examined on a global scale the role of mRNA stability in shaping the kinetics of gene response. Analyzing numerous expression datasets we revealed a striking global anti-correlation between rapidity of induction and mRNA stability, fitting the prediction of a kinetic mathematical model. In contrast, the relationship between kinetics and stability was less significant when gene suppression was analyzed. Frequently, mRNAs that are stable under standard conditions were very rapidly down-regulated following stimulation. Such effect cannot be explained even by a complete shut-off of transcription, and therefore indicates intense modulation of RNA stability. Conclusion Taken together, our results demonstrate the key role of mRNA stability in determining induction kinetics in mammalian transcriptional networks.

  10. Heat shock response in yeast involves changes in both transcription rates and mRNA stabilities.

    Directory of Open Access Journals (Sweden)

    Laia Castells-Roca

    Full Text Available We have analyzed the heat stress response in the yeast Saccharomyces cerevisiae by determining mRNA levels and transcription rates for the whole transcriptome after a shift from 25 °C to 37 °C. Using an established mathematical algorithm, theoretical mRNA decay rates have also been calculated from the experimental data. We have verified the mathematical predictions for selected genes by determining their mRNA decay rates at different times during heat stress response using the regulatable tetO promoter. This study indicates that the yeast response to heat shock is not only due to changes in transcription rates, but also to changes in the mRNA stabilities. mRNA stability is affected in 62% of the yeast genes and it is particularly important in shaping the mRNA profile of the genes belonging to the environmental stress response. In most cases, changes in transcription rates and mRNA stabilities are homodirectional for both parameters, although some interesting cases of antagonist behavior are found. The statistical analysis of gene targets and sequence motifs within the clusters of genes with similar behaviors shows that both transcriptional and post-transcriptional regulons apparently contribute to the general heat stress response by means of transcriptional factors and RNA binding proteins.

  11. Control of mRNA stability during development of Dictyostelium discoideum.

    Science.gov (United States)

    Mangiarotti, G

    1989-01-01

    A large group of mRNA species (which are mainly pre-spore specific) accumulate only after the formation of multicellular aggregates. They are transcribed at a constant rate from the beginning of development and their accumulation is controlled by a 10-20-fold increase in their stability. This mRNA stabilization is dependent upon multicellularity. When aggregates are dispersed, the mRNAs are destabilized; if cells are allowed to reaggregate, the destabilization is reversed. Destabilization is not due to a selective exclusion of mRNA from polyribosomes, but is a primary control event. It does not require synthesis of new RNA or protein, but it may require an interaction between ribosome and the 5'-end of mRNA molecules.

  12. c-Myc inhibits TP53INP1 expression via promoter methylation in esophageal carcinoma

    Energy Technology Data Exchange (ETDEWEB)

    Weng, Wenhao; Yang, Qinyuan [Department of Laboratory Medicine, Shanghai Tenth People' s Hospital, Tongji University School of Medicine, Shanghai 200072 (China); Huang, Miaolong [Department of Thoracic Surgery, Yuebei People' s Hospital, Shaoguan, Guangdong 512026 (China); Qiao, Yongxia [Department of Preventive Medicine, Tongji University, Shanghai City 200092 (China); Xie, Yuan; Yu, Yongchun [Department of Laboratory Medicine, Shanghai Tenth People' s Hospital, Tongji University School of Medicine, Shanghai 200072 (China); Jing, An, E-mail: Anjing77@gmail.com [Department of Thoracic Surgery, Yuebei People' s Hospital, Shaoguan, Guangdong 512026 (China); Institute of Cancer Research, Southern Medical University, Guangzhou 510515 (China); Li, Zhi, E-mail: lizhiweng2010@163.com [Department of Laboratory Medicine, Shanghai Tenth People' s Hospital, Tongji University School of Medicine, Shanghai 200072 (China)

    2011-02-11

    Research highlights: {yields} TP53INP1 expression is down-regulated in esophageal carcinoma and is associated with CGI-131 methylation. {yields} Inhibition of CGI-131 methylation upregulates TP53INP1 expression in ESCC cell lines. {yields} Ectopic expression of TP53INP1 inhibits growth of ESCC cells by inducing apoptosis and inhibiting cell cycle progression. {yields} c-Myc binds to the promoter of TP53INP1 in vivo and vitro and recruits DNMT3A to TP53INP1 promoter for CGI-131 methylation. -- Abstract: Tumor protein p53-induced nuclear protein 1 (TP53INP1) is a well known stress-induced protein that plays a role in both cell cycle arrest and p53-mediated apoptosis. Loss of TP53INP1 expression has been reported in human melanoma, breast carcinoma, and gastric cancer. However, TP53INP1 expression and its regulatory mechanism in esophageal squamous cell carcinoma (ESCC) remain unclear. Our findings are in agreement with previous reports in that the expression of TP53INP1 was downregulated in 28% (10/36 cases) of ESCC lesions, and this was accompanied by significant promoter methylation. Overexpression of TP53INP1 induced G1 cell cycle arrest and increased apoptosis in ESCC cell lines (EC-1, EC-109, EC-9706). Furthermore, our study showed that the oncoprotein c-Myc bound to the core promoter of TP53INP1 and recruited DNA methyltransferase 3A to methylate the local promoter region, leading to the inhibition of TP53INP1 expression. Our findings revealed that TP53INP1 is a tumor suppressor in ESCC and that c-Myc-mediated DNA methylation-associated silencing of TP53INP1 contributed to the pathogenesis of human ESCC.

  13. Lack of cyclin-dependent kinase 4 inhibits c-myc tumorigenic activities in epithelial tissues.

    Science.gov (United States)

    Miliani de Marval, Paula L; Macias, Everardo; Rounbehler, Robert; Sicinski, Piotr; Kiyokawa, Hiroaki; Johnson, David G; Conti, Claudio J; Rodriguez-Puebla, Marcelo L

    2004-09-01

    The proto-oncogene c-myc encodes a transcription factor that is implicated in the regulation of cellular proliferation, differentiation, and apoptosis and that has also been found to be deregulated in several forms of human and experimental tumors. We have shown that forced expression of c-myc in epithelial tissues of transgenic mice (K5-Myc) resulted in keratinocyte hyperproliferation and the development of spontaneous tumors in the skin and oral cavity. Although a number of genes involved in cancer development are regulated by c-myc, the actual mechanisms leading to Myc-induced neoplasia are not known. Among the genes regulated by Myc is the cyclin-dependent kinase 4 (CDK4) gene. Interestingly, previous studies from our laboratory showed that the overexpression of CDK4 led to keratinocyte hyperproliferation, although no spontaneous tumor development was observed. Thus, we tested the hypothesis that CDK4 may be one of the critical downstream genes involved in Myc carcinogenesis. Our results showed that CDK4 inhibition in K5-Myc transgenic mice resulted in the complete inhibition of tumor development, suggesting that CDK4 is a critical mediator of tumor formation induced by deregulated Myc. Furthermore, a lack of CDK4 expression resulted in marked decreases in epidermal thickness and keratinocyte proliferation compared to the results obtained for K5-Myc littermates. Biochemical analysis of the K5-Myc epidermis showed that CDK4 mediates the proliferative activities of Myc by sequestering p21Cip1 and p27Kip1 and thereby indirectly activating CDK2 kinase activity. These results show that CDK4 mediates the proliferative and oncogenic activities of Myc in vivo through a mechanism that involves the sequestration of specific CDK inhibitors.

  14. In vivo inhibition of c-MYC in myeloid cells impairs tumor-associated macrophage maturation and pro-tumoral activities.

    Directory of Open Access Journals (Sweden)

    Oscar M Pello

    Full Text Available Although tumor-associated macrophages (TAMs are involved in tumor growth and metastasis, the mechanisms controlling their pro-tumoral activities remain largely unknown. The transcription factor c-MYC has been recently shown to regulate in vitro human macrophage polarization and be expressed in macrophages infiltrating human tumors. In this study, we exploited the predominant expression of LysM in myeloid cells to generate c-Myc(fl/fl LysM(cre/+ mice, which lack c-Myc in macrophages, to investigate the role of macrophage c-MYC expression in cancer. Under steady-state conditions, immune system parameters in c-Myc(fl/fl LysM(cre/+ mice appeared normal, including the abundance of different subsets of bone marrow hematopoietic stem cells, precursors and circulating cells, macrophage density, and immune organ structure. In a model of melanoma, however, TAMs lacking c-Myc displayed a delay in maturation and showed an attenuation of pro-tumoral functions (e.g., reduced expression of VEGF, MMP9, and HIF1α that was associated with impaired tissue remodeling and angiogenesis and limited tumor growth in c-Myc(fl/fl LysM(cre/+ mice. Macrophage c-Myc deletion also diminished fibrosarcoma growth. These data identify c-Myc as a positive regulator of the pro-tumoral program of TAMs and suggest c-Myc inactivation as an attractive target for anti-cancer therapy.

  15. C-Myc Protein-Protein and Protein-DNA Interactions: Targets for Therapeutic Intervention.

    Science.gov (United States)

    1996-10-01

    progression through the cell cycle (Jansen-Durr et al., 1993; Luscher and Eisenman, 1990). In the mouse, both the c- and N-Myc genes are essential for... Luscher and Eisenman, 1990), the pathways by which it does so seem to be complex. An essential insight into how c-Myc might perform these functions has...Collum and Alt, 1990; Luscher and Eisenman, 1990). Recent experiments support this idea (Amati et al., 1992; Amin et al., 1993; Gu et al., 1993; Kato et al

  16. Codon optimality is a major determinant of mRNA stability.

    Science.gov (United States)

    Presnyak, Vladimir; Alhusaini, Najwa; Chen, Ying-Hsin; Martin, Sophie; Morris, Nathan; Kline, Nicholas; Olson, Sara; Weinberg, David; Baker, Kristian E; Graveley, Brenton R; Coller, Jeff

    2015-03-12

    mRNA degradation represents a critical regulated step in gene expression. Although the major pathways in turnover have been identified, accounting for disparate half-lives has been elusive. We show that codon optimality is one feature that contributes greatly to mRNA stability. Genome-wide RNA decay analysis revealed that stable mRNAs are enriched in codons designated optimal, whereas unstable mRNAs contain predominately non-optimal codons. Substitution of optimal codons with synonymous, non-optimal codons results in dramatic mRNA destabilization, whereas the converse substitution significantly increases stability. Further, we demonstrate that codon optimality impacts ribosome translocation, connecting the processes of translation elongation and decay through codon optimality. Finally, we show that optimal codon content accounts for the similar stabilities observed in mRNAs encoding proteins with coordinated physiological function. This work demonstrates that codon optimization exists as a mechanism to finely tune levels of mRNAs and, ultimately, proteins.

  17. Impact of C-Myc gene-related aberrations in newly diagnosed myeloma with bortezomib/dexamethasone therapy.

    Science.gov (United States)

    Sekiguchi, Naohiro; Ootsubo, Kaori; Wagatsuma, Miyuki; Midorikawa, Kiyoe; Nagata, Akihisa; Noto, Satoshi; Yamada, Kazuaki; Takezako, Naoki

    2014-03-01

    Recent studies have suggested that c-Myc over-expression may be a factor indicating poor prognosis in multiple myeloma (MM), although c-Myc gene-related abnormalities, including translocation and gene amplification, have not been fully investigated in the novel agent era. Additional chromosome 8 may be considered as aggressive disease in the 1990s. To clarify the impact of these aberrations, we retrospectively analyzed newly diagnosed MM (NDMM) and relapsed/refractory MM (RRMM) with bortezomib and dexamethasone induction therapy. In the present study, the high-risk group was defined as having at least one of the following present: non-hyperdiploidy, IgH/FGFR3, and del p53. Forty NDMM cases were analyzed. At the median follow-up duration of 14.1 months, 14 RRMM were recognized. The proportions of patients in the high-risk, c-Myc gene-related aberrations, and additional chromosome 8 groups at diagnosis were 45.5, 22.5, and 10 %, respectively. The proportions of patients who developed RRMM in the high-risk, c-Myc gene-related aberrations, and additional chromosome 8 groups were 41.7, 77.7, and 50 %, respectively. Furthermore, patients with c-Myc gene-related abnormalities tended to exhibit inferior progression-free survival (PFS), and those with c-Myc gene-related abnormalities and/or additional chromosome 8 showed statistically shorter PFS. Therefore, c-Myc gene-related abnormalities and additional chromosome 8 may be related to a poorer prognosis.

  18. Erythropoietin activates two distinct signaling pathways required for the initiation and the elongation of c-myc

    Science.gov (United States)

    Chen, C.; Sytkowski, A. J.

    2001-01-01

    Erythropoietin (Epo) stimulation of erythroid cells results in the activation of several kinases and a rapid induction of c-myc expression. Protein kinase C is necessary for Epo up-regulation of c-myc by promoting elongation at the 3'-end of exon 1. PKCepsilon mediates this signal. We now show that Epo triggers two signaling pathways to c-myc. Epo rapidly up-regulated Myc protein in BaF3-EpoR cells. The phosphatidylinositol 3-kinase (PI3K) inhibitor LY294002 blocked Myc up-regulation in a concentration-dependent manner but had no effect on the Epo-induced phosphorylation of ERK1 and ERK2. LY294002 also had no effect on Epo up-regulation of c-fos. MEK1 inhibitor PD98059 blocked both the c-myc and the c-fos responses to Epo. PD98059 and the PKC inhibitor H7 also blocked the phosphorylation of ERK1 and ERK2. PD98059 but not LY294002 inhibited Epo induction of ERK1 and ERK2 phosphorylation in normal erythroid cells. LY294002 blocked transcription of c-myc at exon 1. PD98059 had no effect on transcription from exon 1 but, rather, blocked Epo-induced c-myc elongation at the 3'-end of exon 1. These results identify two Epo signaling pathways to c-myc, one of which is PI3K-dependent operating on transcriptional initiation, whereas the other is mitogen-activated protein kinase-dependent operating on elongation.

  19. Stability of Human Follicle-Stimulating Hormone Receptor mRNA in Stably Transfected Cells

    Institute of Scientific and Technical Information of China (English)

    朱长虹; 田红

    2001-01-01

    In order to assess the impact of mRNA degradation on steady state levels of follicle-stimulating hormone receptor (FSHR) mRNA and on regulation of FSHR gene expression, the stability and half-life of FSHR mRNA were determined in transfected cells expressing recombinant FSHR. Time-dependent changes in FSHR mRNA content were determined by nuclease protection-solution hybridization assay (NPA) or by qualitative reverse transcription-competitive polymerase chain reaction (RT-PCR) in cultured hFSHR-YI cells, cell lines stably transfected with a human FSHR cDNA. FSHR mRNA content remained constant during 8 h control incubations of hFSHR-Y1 cells (NPA, 2.9±0.3 μg/mg RNA; RT-PCR, 2.7±0.3 μg/mg RNA). Actinomycin D (ActD, 5 μg/ml) inhibited mRNA synthesis, as assessed by incorporation of [3 H]uridine into total RNA, by 90 % within 1 h in hFSHR-Y1 cells. No effect of ActD on cellular morphology or viability was observed. ActD caused a time-dependent decrease in FSHR mRNA content in hFSHR-Y1 cell lines with a lag time of 1 h. There were no significant differences in the rate of FSHR mRNA degradation between the two methods of mRNA quantification. The half-life of hFSHR mRNA was 3.6±0.2 h by NPA and 3.1±0.1 h by RT-PCR. The results indicated that degradation of mRNA was an important process in maintenance of steady state expression of the FSHR gene in cells stably expressing recombinant receptor.

  20. 人胎冠状动脉原位杂交c-myc和jun原癌基因表达%Expression of proto - oncogenes c - myc and jun in human coronary artery ruring development

    Institute of Scientific and Technical Information of China (English)

    蔡维君; 陈新平; 伍校琼; 罗学港

    2004-01-01

    目的研究原癌基因c-myc和jun在人胎冠状动脉发育过程中的表达与平滑肌细胞增殖的关系.方法用原位杂交方法检测,胎龄分别为16周、22周(因治疗需要引产)的胎儿和意外死亡的足月胎儿冠状动脉前降支c-myc mRNA和jun mRNA的表达水平.杂交反应产物用图像分析仪(MIAS300)作定量分析.结果C-myc mRNA原位杂交反应产物与被测血管区域面积的百分比在16周、22周和足月胎儿分别是70、56和10;Jun mRNA的杂交信反应产物与被测血管区域面积的百分比在这三个时期分别是68、53和8.两个原癌基因在不同阶段的表达均具有显著性差异.结论本实验首次报道c-myc和jun在人胎冠状动脉发育过程中平滑肌的表达图型,c-myc和jun在胎儿冠状动脉平滑肌细胞增殖和内膜的形成过程中可能具有重要的调控作用.%Objective: To investigate the expression of protooncogenes, c - myc and jun, in human coronary artery during development. Methods: In situ hybridization was employed to detect c - myc mRNA and jun mRNA in human coronary artery from aborted fetus with embryonic ages from week 16 to 22 due to treatment requirements. In addition, 3 cases of full term human fetus died of accident were also studied. Hybridized signals were quantified with a computer - assisted image - analyzing system ( MIAS 300 ). Results: The ratio of hybridized signal of c - myc to the area of vascular wall detected were 0.7, 0.54 and 0.10 respectively corresponding to the embryonic ages, 16 weeks,22 weeks and full term. Similar results with the ratio of 0.68, 0.53 and 0.08 for jun mRNA at above embryonic ages was also found. The levels of c - myc and jun mRNA expressed at different embryonic stage showed a significant difference. Conclusions: We first reported the expression of proto - oncogenes, c - myc and jun, in human coronary artery during embryonic development. These two proto - oncogenes may play an important role in the

  1. Oestradiol reduces Liver Receptor Homolog-1 mRNA transcript stability in breast cancer cell lines

    Energy Technology Data Exchange (ETDEWEB)

    Lazarus, Kyren A. [Cancer Drug Discovery Laboratory, Prince Henry’s Institute of Medical Research, Clayton, Victoria 3168 (Australia); Environmental and Biotechnology Centre, Swinburne University, Hawthorn, Victoria 3122 (Australia); Zhao, Zhe; Knower, Kevin C. [Cancer Drug Discovery Laboratory, Prince Henry’s Institute of Medical Research, Clayton, Victoria 3168 (Australia); To, Sarah Q. [Cancer Drug Discovery Laboratory, Prince Henry’s Institute of Medical Research, Clayton, Victoria 3168 (Australia); Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria 3168 (Australia); Chand, Ashwini L. [Cancer Drug Discovery Laboratory, Prince Henry’s Institute of Medical Research, Clayton, Victoria 3168 (Australia); Clyne, Colin D., E-mail: Colin.clyne@princehenrys.org [Cancer Drug Discovery Laboratory, Prince Henry’s Institute of Medical Research, Clayton, Victoria 3168 (Australia); Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria 3168 (Australia)

    2013-08-30

    Highlights: •LRH-1 is an orphan nuclear receptor that regulates tumor proliferation. •In breast cancer, high mRNA expression is associated with ER+ status. •In ER−ve cells, despite very low mRNA, we found abundant LRH-1 protein. •Our data show distinctly different LRH-1 protein isoforms in ER− and ER+ breast cancer cells. •This is due to differences in LRH-1 mRNA and protein stability rates. -- Abstract: The expression of orphan nuclear receptor Liver Receptor Homolog-1 (LRH-1) is elevated in breast cancer and promotes proliferation, migration and invasion in vitro. LRH-1 expression is regulated by oestrogen (E{sub 2}), with LRH-1 mRNA transcript levels higher in oestrogen receptor α (ERα) positive (ER+) breast cancer cells compared to ER− cells. However, the presence of LRH-1 protein in ER− cells suggests discordance between mRNA transcript levels and protein expression. To understand this, we investigated the impact of mRNA and protein stability in determining LRH-1 protein levels in breast cancer cells. LRH-1 transcript levels were significantly higher in ER+ versus ER− breast cancer cells lines; however LRH-1 protein was expressed at similar levels. We found LRH-1 mRNA and protein was more stable in ER− compared to ER+ cell lines. The tumor-specific LRH-1 variant isoform, LRH-1v4, which is highly responsive to E{sub 2}, showed increased mRNA stability in ER− versus ER+ cells. In addition, in MCF-7 and T47-D cell lines, LRH-1 total mRNA stability was reduced with E{sub 2} treatment, this effect mediated by ERα. Our data demonstrates that in ER− cells, increased mRNA and protein stability contribute to the abundant protein expression levels. Expression and immunolocalisation of LRH-1 in ER− cells as well as ER− tumors suggests a possible role in the development of ER− tumors. The modulation of LRH-1 bioactivity may therefore be beneficial as a treatment option in both ER− and ER+ breast cancer.

  2. Disturbance of Bcl-2, Bax, Caspase-3, Ki-67 and C-myc expression in acute and subchronic exposure to benzo(a)pyrene in cervix.

    Science.gov (United States)

    Gao, Meili; Li, Yongfei; Ji, Xiaoying; Xue, Xiaochang; Chen, Lan; Feng, Guodong; Zhang, Huqin; Wang, Huichun; Shah, Walayat; Hou, Zhanwu; Kong, Yu

    2016-03-01

    Epidemiological studies have demonstrated that cigarette smoking is an important cofactor or an independent risk factor for the development of cervical cancer. Benzo(a)pyrene (BaP) is one of the most potent tobacco smoke carcinogens in tobacco smoke. BaP induced DNA damage and over expression in p53 cervical tissue of mice as demonstrated in our previous study. Here we present the findings of exposure to BaP on the expression of Bcl-2, C-myc, Ki-67, Caspase-3 and Bax genes in mouse cervix. Acute intraperitoneal administration of BaP (12.5, 25, 50, 100mg/kg body weight) to ICR female mice induced a significant increase in Bcl-2, C-myc, Ki-67 mRNA and protein level till 72h except in Bcl-2 at 24h with 12.5, 25, 50mg/kg as well as at 48h with 12.5mg/kg body weight post treatment. A significant increase was also seen in Caspase-3 and Bax mRNA and protein level with peak level at 24h and gradual decrease till 72h, however, the expression of caspase-3 increased while that of Bax decreased with increasing dose of Bap after 24h. In sub chronic intraperitoneal and oral gavage administration of BaP (2.5, 5, 10mg/kg body weight), similar significant increase was observed for all the examined genes as compared to the control and vehicle groups, however the expression of Bax decreased in a dose dependent manner. The findings of this study will help in further understanding the molecular mechanism of BaP induced carcinogenesis of cervical cancer.

  3. C-MYC positive angiosarcoma of skin and breast following MammoSite® treatment.

    Science.gov (United States)

    Tidwell, W James; Haq, Jim; Kozlowski, Kamila F; Googe, Paul B

    2015-10-16

    Angiosarcoma of the skin and breast is a known complication of chronic lymphedema following mastectomy or external radiation therapy for breast cancer. We report a 68-year-old woman who presented with a 2.5 cm violaceous plaque on the skin of the right breast and a 3 cm mixed mass of the same breast by ultrasound 9 years after MammoSite® balloon brachytherapy.  Biopsy of the skin lesion and the breast mass showed an infiltrating high grade angiosarcoma.  The tumor cells in the skin and breast showed immunohistochemical reactivity for C-MYC.  A total mastectomy confirmed the presence of high grade angiosarcoma in the skin and parenchyma of the breast and radiation changes in the breast parenchyma.  Surgical margins were considered negative.  The patient had cutaneous recurrence of angiosarcoma three months after the mastectomy.  There have been only two other case reports in the literature of angiosarcoma on the skin following MammoSite® therapy. The c-myc mutation has been shown to be a specific mutation for angiosarcoma following radiation treatment. It is not found in atypical vascular lesions following irradiation or angiosarcoma unrelated to radiation treatment.

  4. bcl-1, bcl-2, p53, c-myc, and lyt-10 analysis in cutaneous lymphomas.

    Science.gov (United States)

    Garatti, S A; Roscetti, E; Trecca, D; Fracchiolla, N S; Neri, A; Berti, E

    1995-01-01

    In the present study we investigated the pathogenetic role of c-myc, bcl-2, and lyt-10 oncogenes, bcl-1 locus, and p53 suppressor gene in a representative panel of cutaneous lymphomas, including 25 cases of cutaneous B cell lymphoma (CBCL) and 29 cases of cutaneous T cell lymphoma (CTCL). In our analysis four cases of CBCL were found rearranged for bcl-2 and two for the bcl-1 locus. Two cases of CTCL and one case of CBCL were found rearranged for lyt-10. No rearrangements of c-myc oncogene were found in CBCL. Analysis of p53 gene showed mutation only in one case of mycosis fungoides in tumoral stage, at codon 163 of p53 gene (TAC-->CAC; Tyr--> Asp). Our data suggest that in primary CBCL bcl-2 oncogenes and bcl-1 locus are rarely involved. Furthermore, in primary CTCL p53 gene is not affected at significant frequency. The occurrence of p53 mutation in a patient affected by mycosis fungoides in tumoral stage may represent an involvement of p53 gene in tumor progression of CTCL, a finding observed in several types of human cancer.

  5. C-Myc regulation by costimulatory signals modulates the generation of CD8+ memory T cells during viral infection.

    Science.gov (United States)

    Haque, Mohammad; Song, Jianyong; Fino, Kristin; Wang, Youfei; Sandhu, Praneet; Song, Xinmeng; Norbury, Christopher; Ni, Bing; Fang, Deyu; Salek-Ardakani, Shahram; Song, Jianxun

    2016-01-01

    The signalling mechanisms of costimulation in the development of memory T cells remain to be clarified. Here, we show that the transcription factor c-Myc in CD8(+) T cells is controlled by costimulatory molecules, which modulates the development of memory CD8(+) T cells. C-Myc expression was dramatically reduced in Cd28(-/-) or Ox40(-/-) memory CD8(+) T cells, and c-Myc over-expression substantially reversed the defects in the development of T-cell memory following viral infection. C-Myc regulated the expression of survivin, an inhibitor of apoptosis, which promoted the generation of virus-specific memory CD8(+) T cells. Moreover, over-expression of survivin with bcl-xL, a downstream molecule of NF-κB and intracellular target of costimulation that controls survival, in Cd28(-/-) or Ox40(-/-) CD8(+) T cells, reversed the defects in the generation of memory T cells in response to viral infection. These results identify c-Myc as a key controller of memory CD8(+) T cells from costimulatory signals.

  6. Depressive Effect of the Antisense Oligonucleotides of C-myc and PCNA on the Proliferation of VSMC

    Institute of Scientific and Technical Information of China (English)

    Qingxian Li; Yanfu Wang; Yuhua Liao; Huiling Zhang; Yanying Jiang

    2007-01-01

    To study the depressive effect of the antisense oligonuceotides (ASODN) of c-myc and proliferating cell nuclear antigen (PCNA) on the proliferation of VSMC.Methods Taking the VSMC obtained from rat aorta thoracalis cultured 4 ~ 8 generation as research object.The objects were divided into three groups to carry out control study:control group,PCNA ASODN group and c-myc ASODN group.The ASODNs' working concentration all were 1:50.The depressive effect of ASODN on VSMC proliferation was investigated by cell counting,MTT and 3H-TdR incorporation assay;PCNA and c-myc expression were detected by immunohistochemical method after transferring PCNA successfully;the corresponding gene was inhibited obviously;compared with control group ( P < 0.05 ).Conclusions PCNA and c-myc might play a considerable role in the VSMC proliferation process.The corresponding gene could be depressed successfully after transferring PCNA and c-myc ASODN into VSMC,and then the proliferation of VSMC was slowed down.This study presented a beneficial proposal and theoretical fundament for atherosclerotic treatment.

  7. Infection by Toxoplasma gondii Specifically Induces Host c-Myc and the Genes This Pivotal Transcription Factor Regulates

    Science.gov (United States)

    Franco, Magdalena; Shastri, Anjali J.

    2014-01-01

    Toxoplasma gondii infection has previously been described to cause dramatic changes in the host transcriptome by manipulating key regulators, including STATs, NF-κB, and microRNAs. Here, we report that Toxoplasma tachyzoites also mediate rapid and sustained induction of another pivotal regulator of host cell transcription, c-Myc. This induction is seen in cells infected with all three canonical types of Toxoplasma but not the closely related apicomplexan parasite Neospora caninum. Coinfection of cells with both Toxoplasma and Neospora still results in an increase in the level of host c-Myc, showing that c-Myc is actively upregulated by Toxoplasma infection (rather than repressed by Neospora). We further demonstrate that this upregulation may be mediated through c-Jun N-terminal protein kinase (JNK) and is unlikely to be a nonspecific host response, as heat-killed Toxoplasma parasites do not induce this increase and neither do nonviable parasites inside the host cell. Finally, we show that the induced c-Myc is active and that transcripts dependent on its function are upregulated, as predicted. Hence, c-Myc represents an additional way in which Toxoplasma tachyzoites have evolved to specifically alter host cell functions during intracellular growth. PMID:24532536

  8. Effect of c-myc on the ultrastructural structure of cochleae in guinea pigs with noise induced hearing loss

    Energy Technology Data Exchange (ETDEWEB)

    Han, Yu; Zhong, Cuiping [Department of Otolaryngology, Xijing Hospital, Fourth Military Medical University, Xi' an, 710032 Shaanxi Province (China); Hong, Liu [First Division of Digestive Diseases, Xijing Hospital, Fourth Military Medical University, Xi' an, 710032 Shaanxi Province (China); Wang, Ye; Qiao, Li [Department of Otolaryngology, Xijing Hospital, Fourth Military Medical University, Xi' an, 710032 Shaanxi Province (China); Qiu, Jianhua, E-mail: qiujh@fmmu.edu.cn [Department of Otolaryngology, Xijing Hospital, Fourth Military Medical University, Xi' an, 710032 Shaanxi Province (China)

    2009-12-18

    Noise over-stimulation may induce hair cells loss and hearing deficit. The c-myc oncogene is a major regulator for cell proliferation, growth, and apoptosis. However, the role of this gene in the mammalian cochlea is still unclear. The study was designed to firstly investigate its function under noise condition, from the aspect of cochlear ultrastructural changes. We had established the adenoviral vector of c-myc gene and delivered the adenovirus suspension into the scala tympani of guinea pigs 4 days before noise exposure. The empty adenoviral vectors were injected as control. Then, all subjects were exposed to 4-kHz octave-band noise at 110 dB SPL for 8 h/day, 3 days consecutively. Auditory thresholds were assessed by auditory brainstem response, prior to and 7 days following noise exposure. On the seventh days after noise exposure, the cochlear sensory epithelia surface was observed microscopically and the cochleae were taken to study the ultrastructural changes. The results indicated that auditory threshold shift after noise exposure was higher in the ears treated with Ad.EGFP than that treated with Ad.c-myc-EGFP. Stereocilia loss and the disarrangement of outer hair cells were observed, with greater changes found in the Ad.EGFP group. Also, the ultrastructure changes were severe in the Ad.EGFP group, but not obvious in the Ad.c-myc-EGFP group. Therefore, c-myc gene might play an unexpected role in hearing functional and morphological protection from acoustic trauma.

  9. Transient in utero knockout (TIUKO of C-MYC affects late lung and intestinal development in the mouse

    Directory of Open Access Journals (Sweden)

    Zhou Pengbo

    2004-04-01

    Full Text Available Abstract Background Developmentally important genes often result in early lethality in knockout animals. Thus, the direct role of genes in late gestation organogenesis cannot be assessed directly. In utero delivery of transgenes was shown previously to result in high efficiency transfer to pulmonary and intestinal epithelial stem cells. Thus, this technology can be used to evaluate late gestation development. Results In utero gene transfer was used to transfer adenovirus with either an antisense c-myc or a C-MYC ubiquitin targeting protein to knockout out c-myc expression in late gestation lung and intestines. Using either antisense or ubiquitin mediated knockout of C-MYC levels in late gestation resulted in similar effects. Decreased complexity was observed in both intestines and lungs. Stunted growth of villi was evident in the intestines. In the lung, hypoplastic lungs with disrupted aveolarization were observed. Conclusions These data demonstrated that C-MYC was required for cell expansion and complexity in late gestation lung and intestinal development. In addition they demonstrate that transient in utero knockout of proteins may be used to determine the role of developmentally important genes in the lungs and intestines.

  10. Modulation of Cellular Migration and Survival by c-Myc through the Downregulation of Urokinase (uPA) and uPA Receptor▿ †

    Science.gov (United States)

    Alfano, Daniela; Votta, Giuseppina; Schulze, Almut; Downward, Julian; Caputi, Mario; Stoppelli, Maria Patrizia; Iaccarino, Ingram

    2010-01-01

    It has been proposed that c-Myc proapoptotic activity accounts for most of its restraint of tumor formation. We established a telomerase-immortalized human epithelial cell line expressing an activatable c-Myc protein. We found that c-Myc activation induces, in addition to increased sensitivity to apoptosis, reductions in cell motility and invasiveness. Transcriptome analysis revealed that urokinase (uPA) and uPA receptor (uPAR) were strongly downregulated by c-Myc. Evidence is provided that the repression of uPA and uPAR may account for most of the antimigratory and proapoptotic activities of c-Myc. c-Myc is known to cooperate with Ras in cellular transformation. We therefore investigated if this cooperation could converge in the control of uPA/uPAR expression. We found that Ras is able to block the effects of c-Myc activation on apoptosis and cellular motility but not on cell invasiveness. Accordingly, the activation of c-Myc in the context of Ras expression had only minor influence on uPAR expression but still had a profound repressive effect on uPA expression. Thus, the differential regulation of uPA and uPAR by c-Myc and Ras correlates with the effects of these two oncoproteins on cell motility, invasiveness, and survival. In conclusion, we have discovered a novel link between c-Myc and uPA/uPAR. We propose that reductions of cell motility and invasiveness could contribute to the inhibition of tumorigenesis by c-Myc and that the regulation of uPA and uPAR expression may be a component of the ability of c-Myc to reduce motility and invasiveness. PMID:20123981

  11. Modulation of cellular migration and survival by c-Myc through the downregulation of urokinase (uPA) and uPA receptor.

    Science.gov (United States)

    Alfano, Daniela; Votta, Giuseppina; Schulze, Almut; Downward, Julian; Caputi, Mario; Stoppelli, Maria Patrizia; Iaccarino, Ingram

    2010-04-01

    It has been proposed that c-Myc proapoptotic activity accounts for most of its restraint of tumor formation. We established a telomerase-immortalized human epithelial cell line expressing an activatable c-Myc protein. We found that c-Myc activation induces, in addition to increased sensitivity to apoptosis, reductions in cell motility and invasiveness. Transcriptome analysis revealed that urokinase (uPA) and uPA receptor (uPAR) were strongly downregulated by c-Myc. Evidence is provided that the repression of uPA and uPAR may account for most of the antimigratory and proapoptotic activities of c-Myc. c-Myc is known to cooperate with Ras in cellular transformation. We therefore investigated if this cooperation could converge in the control of uPA/uPAR expression. We found that Ras is able to block the effects of c-Myc activation on apoptosis and cellular motility but not on cell invasiveness. Accordingly, the activation of c-Myc in the context of Ras expression had only minor influence on uPAR expression but still had a profound repressive effect on uPA expression. Thus, the differential regulation of uPA and uPAR by c-Myc and Ras correlates with the effects of these two oncoproteins on cell motility, invasiveness, and survival. In conclusion, we have discovered a novel link between c-Myc and uPA/uPAR. We propose that reductions of cell motility and invasiveness could contribute to the inhibition of tumorigenesis by c-Myc and that the regulation of uPA and uPAR expression may be a component of the ability of c-Myc to reduce motility and invasiveness.

  12. Hsa-let-7a functions as a tumor suppressor in renal cell carcinoma cell lines by targeting c-myc

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Yongchao; Yin, Bingde; Zhang, Changcun; Zhou, Libin [Department of Urology, Shanghai First People' s Hospital, School of Medicine, Shanghai Jiaotong University, Shanghai 200080 (China); Fan, Jie, E-mail: jief67@sina.com [Department of Urology, Shanghai First People' s Hospital, School of Medicine, Shanghai Jiaotong University, Shanghai 200080 (China)

    2012-01-06

    Highlights: Black-Right-Pointing-Pointer This study is the first to test the let-7a/c-myc loop in renal cell carcinoma cell lines. Black-Right-Pointing-Pointer Let-7a down-regulated c-myc in three renal cell carcinoma cell lines. Black-Right-Pointing-Pointer c-myc target genes were down-regulated because of the let-7a-mediated down-regulation of c-myc. Black-Right-Pointing-Pointer The let-7a/c-myc loop has a significant function in renal cell carcinoma cell lines. -- Abstract: Widespread functions of the c-myc pathway play a crucial role in renal cell carcinoma (RCC) carcinogenesis. Thus, we evaluated the connection between proto-oncogenic c-myc and anti-neoplastic hsa-let-7a (let-7a) in RCC cell lines. The levels of c-myc and let-7a in 3 RCC cell lines (769P, Caki-1 and 786O) were measured after transfecting the cells with let-7a mimics or a negative control. The change in c-myc protein level was confirmed by Western blot. The anti-neoplastic function of let-7a was evaluated using cell counting kit-8 (CCK-8) for proliferation analysis and cell flow cytometry for cell cycle analysis. The changes of downstream targets of c-myc were measured using reverse transcription quantitative real-time PCR (qRT-PCR). Our results suggest for the first time that let-7a acts as a tumor suppressor in RCC cell lines by down-regulating c-myc and c-myc target genes such as proliferating cell nuclear antigen (PCNA), cyclin D1 (CCND1) and the miR17-92 cluster, which is accompanied by proliferation inhibition and cell cycle arrest.

  13. Butyrate inhibits pro-proliferative miR-92a by diminishing c-Myc-induced miR-17-92a cluster transcription in human colon cancer cells.

    Science.gov (United States)

    Hu, Shien; Liu, Lan; Chang, Eugene B; Wang, Jian-Ying; Raufman, Jean-Pierre

    2015-10-13

    Compromised colonic butyrate production resulting from low dietary fiber or altered gut microbiota may promote colon neoplasia. Previous reports indicate these actions are mediated in part by altered levels of miRNAs, including suppressed expression of the oncogenic miR-17-92a cluster. Here, we sought to identify the mechanisms underlying these effects of butyrate in colon cancer. miR-92a levels were measured in archived human colon cancer and adjacent normal colon specimens by microarray and quantitative RT-PCR (qPCR). The effects of butyrate and other histone deacetylase inhibitors (suberoylanilide hydroxamic acid (SAHA) and valproic acid) on primary (pri-miR17-92a), precursor and mature miR-92a were analyzed in HCT-116 and HT-29 human colon cancer cells using qPCR. The effects of butyrate, SAHA and valproic acid on protein levels of c-Myc, Drosha and p57 were measured in HCT-116 cells using immunoblotting. Regulation of C13orf25 promoter activity by butyrate was analyzed by luciferase reporter assay using modified pGL3 constructs containing a wild-type or mutated c-Myc binding site. Expression of c-Myc was modulated using siRNA or adenovirus vectors. p57 mRNA and protein were measured before and after transfection with miR-92a-mimic molecules. Following butyrate treatment and miR-92a-mimic transfection, apoptosis was analyzed by TUNEL staining and caspase-3 immunoblotting. Microarray, confirmed by qPCR, revealed a seven-fold increase in miR-92a levels in sporadic human colon cancer tissue compared to adjacent normal colon. Treating human colon cancer cells with butyrate reduced the levels of pri-miR17-92a, precursor and mature miR-92a, as well as c-Myc. SAHA and valproic acid had similar effects. Mutation of the c-Myc binding site diminished butyrate's inhibitory effects on C13orf25 promoter activity. Silencing c-Myc expression reduced miR-92a levels. c-Myc over-expression neutralized butyrate-induced attenuation of pri-miR17-92a. Exogenous miR-92a inhibited

  14. Targeting angiogenesis via a c-Myc/hypoxia-inducible factor-1alpha-dependent pathway in multiple myeloma.

    Science.gov (United States)

    Zhang, Jing; Sattler, Martin; Tonon, Giovanni; Grabher, Clemens; Lababidi, Samir; Zimmerhackl, Alexander; Raab, Marc S; Vallet, Sonia; Zhou, Yiming; Cartron, Marie-Astrid; Hideshima, Teru; Tai, Yu-Tzu; Chauhan, Dharminder; Anderson, Kenneth C; Podar, Klaus

    2009-06-15

    Bone marrow angiogenesis is associated with multiple myeloma (MM) progression. Here, we report high constitutive hypoxia-inducible factor-1alpha (Hif-1alpha) expression in MM cells, which is associated with oncogenic c-Myc. A drug screen for anti-MM agents that decrease Hif-1alpha and c-Myc levels identified a variety of compounds, including bortezomib, lenalidomide, enzastaurin, and adaphostin. Functionally, based on transient knockdowns and overexpression, our data delineate a c-Myc/Hif-1alpha-dependent pathway mediating vascular endothelial growth factor production and secretion. The antiangiogenic activity of our tool compound, adaphostin, was subsequently shown in a zebrafish model and translated into a preclinical in vitro and in vivo model of MM in the bone marrow milieu. Our data, therefore, identify Hif-1alpha as a novel molecular target in MM and add another facet to anti-MM drug activity.

  15. The reducing agent Dithiothreitol (DTT) increases expression of c-myc and c- fos protooncogenes in human cells

    DEFF Research Database (Denmark)

    Skouv, J.; Sørensen, Ilona Kryspin; Frandsen, H.

    1995-01-01

    . The genes were two proto-oncogenes, c-fos and c-myc, and the tumour suppressor gene, p53. We observed that the expression of the c-fos and c-myc genes was induced when human bladder epithelial cells were treated with a standard solution of N-OH-PhIP and dithiothreitol (DTT), previously shown to be genotoxic....... However, when cells were treated with DTT alone, the expression of c-fos and c-myc was also transiently induced. We therefore conclude that DTT, and not N-OH-PhIP, induced oncogene expression. Induction of both c-fos and c-mye expression by a reducing agent, DTT, which is frequently used in in vitro...

  16. Functional divergence of duplicated c-myc genes in a tetraploid fish, the common carp (Cyprinus carpio).

    Science.gov (United States)

    Futami, Kunihiko; Zhang, Huan; Okamoto, Nobuaki

    2005-12-19

    The proto-oncogene c-myc is thought to be one of the most important genes in controlling cell proliferation. In a tetraploid fish, two c-myc genes (CAM1 and CAM2) were previously isolated from the common carp, Cyprinus carpio, and were shown to have different expression patterns in adult tissues. Here we found that CAM1 and CAM2 proteins had distinct properties in terms of their transcription regulation system, formation of the transcription activator complex Myc/Max, and transcriptional activation of the target gene. These results showed that the two carp c-Myc proteins have overlapping but distinct functions, suggesting that CAM1 and CAM2 are evolving to acquire different functions after an earlier tetraploidization event.

  17. The CT-Element of The C-Myc Gene Does Not Predispose to Chromosomal Breakpoints in Burkitt'S Lymphoma

    Directory of Open Access Journals (Sweden)

    Achim Weber

    2006-01-01

    Full Text Available Background: Chromosomal translocations are causally related to the development of many tumors. In Burkitt's lymphoma, abnormalities involving the c-myc gene are essential. The CT-element of the c-myc promoter adopts non-B-conformation in vivo and in vitro, and therefore provides a potential fragile site. Methods: We have developed a LM-PCR-based approach to test if chromosomal breakpoints indeed cluster in this region. Results: Amplifying both, wild-type as well as the translocated c-myc gene by LM-PCR, it was shown that chromosomal breakpoints did not cluster within the CT-element. Conclusions: Therefore, the CT-element is not especially susceptible to the formation of breakpoints leading to chromosomal translocations in Burkitt's lymphoma.

  18. Alterations of C-MYC, NKX3.1, and E-cadherin expression in canine prostate carcinogenesis

    DEFF Research Database (Denmark)

    Fonseca-Alves, Carlos E; Rodrigues, Marcela M P; de Moura, Veridiana M B D;

    2013-01-01

    therapies. In humans, the PCa frequently exhibits mutations in the C-MYC and a reduced expression of the E-cadherin and NKX3.1 proteins. This study's objective was to evaluate the NKX3.1, C-MYC, and E-cadherin expression in the canine normal prostate, benign prostatic hyperplasia (BPH), proliferative......The dog (canis lupus familiaris) is the only other species besides humans that develop spontaneous prostatic carcinomas (PCa) at a high frequency. The canine model is primarily utilized for the study of the PCa molecular mechanisms and provides a natural animal model for the study of potential...... inflammatory atrophy (PIA) and PCa and to verify differences in expression and subcellular localization of these proteins in the prostatic carcinogenesis. A tissue microarray (TMA) slide was constructed, and immunohistochemistry with antibodies raised against C-MYC, NKX3.1, E-cadherin and p63 was performed...

  19. Thermal injuries induce gene expression of endogenous c-fos, c-myc and bFGF in burned tissues

    Institute of Scientific and Technical Information of China (English)

    付小兵; 顾小曼; 孙同柱; 杨银辉; 孙晓庆; 盛志勇

    2003-01-01

    Objective To investigate the expression sequence and distribution characteristics of the protooncogenes c-fos, c-myc and endogenous basic fibroblast growth factor (bFGF ) genes in burned tissues, and to explore the possible effects of changes in the se genes' functions on wound healing. Methods Partial-thickness burns of 30% TBSA were established on backs of Wistar rats. Insitu hybridization and histological methods were used to detect expression of c-fos, c-myc and bFGF genes in normal and burned tissue at 3 h, 6 h, 1 d, 3 d , 7 d and 14 d postburn. Results Although expression of c-fos and c-myc genes and bFGF gene could be found in normal skin, the expression of all three were markedly induced by burn wounds and the expression models in sequence and distribution were quite different. Expre ssion of c-fos gene increased and peaked at 6 h. Signals were mainly localiz ed in both nuclei of dermal fibroblasts and monocytes. The expression of bFGF gene increased at 6 h and peaked at 1 d postburn, and was distributed in the cyt oplasm of fibroblasts. C-myc gene peaked 3 d postburn and was also distributed in the cytoplasm of fibroblasts. Conclusions These results indicated that thermal injury could induce the expression of c-fos, c-myc and bFGF at gene level, showing phasic control and regional distributi on. The phasic expression of these genes suggests that there is an interaction between protooncogenes and bFGF, which may play an important role in wound heali ng. The different expressions of c-fos and c-myc play an inducing role in reg ulating bFGF, and in turn affect wound healing.

  20. Elevation of c-MYC disrupts HLA class II-mediated immune recognition of human B cell tumors.

    Science.gov (United States)

    God, Jason M; Cameron, Christine; Figueroa, Janette; Amria, Shereen; Hossain, Azim; Kempkes, Bettina; Bornkamm, Georg W; Stuart, Robert K; Blum, Janice S; Haque, Azizul

    2015-02-15

    Elevated levels of the transcription factor c-myc are strongly associated with various cancers, and in particular B cell lymphomas. Although many of c-MYC's functions have been elucidated, its effect on the presentation of Ag through the HLA class II pathway has not been reported previously. This is an issue of considerable importance, given the low immunogenicity of many c-MYC-positive tumors. We report in this paper that increased c-MYC expression has a negative effect on the ability of B cell lymphomas to functionally present Ags/peptides to CD4(+) T cells. This defect was associated with alterations in the expression of distinct cofactors as well as interactions of antigenic peptides with class II molecules required for the presentation of class II-peptide complexes and T cell engagement. Using early passage Burkitt's lymphoma (BL) tumors and transformed cells, we show that compared with B lymphoblasts, BL cells express decreased levels of the class II editor HLA-DM, lysosomal thiol-reductase GILT, and a 47-kDa enolase-like protein. Functional Ag presentation was partially restored in BL cells treated with a c-MYC inhibitor, demonstrating the impact of this oncogene on Ag recognition. This restoration of HLA class II-mediated Ag presentation in early passage BL tumors/cells was linked to enhanced HLA-DM expression and a concurrent decrease in HLA-DO in BL cells. Taken together, these results reveal c-MYC exerts suppressive effects at several critical checkpoints in Ag presentation, which contribute to the immunoevasive properties of BL tumors.

  1. EFFECT OF STENT ABSORBED c-myc ANTISENSE OLIGODEOXYNUCLEOTIDE ON SMOOTH MUSCLE CELLS APOPTOSIS IN RABBIT CAROTID ARTERY

    Institute of Scientific and Technical Information of China (English)

    张新霞; 崔长琮; 李江; 崔翰斌; 徐仓宝; 朱参战

    2002-01-01

    Objective To investigate the effect of gelatin coated Platinium-Iridium stent absorbed c-myc antisense oligodeoxynucleotide (ASODN) on smooth muscle cells apoptosis in a normal rabbit carotid arteries. Methods Gelatin coated Platinium-Iridium stents were implanted in the right carotid arteries of 32 rabbits under vision. Animals were randomly divided into control group and treated group receiving c-myc ASODN (n=16, respectively). On 7, 14, 30 and 90 days following the stenting procedure ,morphometry for caculation of neointimal area and mean neointimal thickness were performed.The expression of c-myc protein was detected by immunohistochemical method. Apoptotic smooth muscle cells was detected by terminal deoxynucleotidyl transferase mediated dUTP nick end labeling (TUNEL). Results At 7 and 14 days after stenting,there were no detectable apoptotic cells in both groups. The apoptotic cells occurred in the neointima 30 and 90 days after stenting, and the number of apoptotic cells at 30 days were less [4.50±1.29 vs 25.75±1.89 (number/0.1mm2)] than that at 90 days [13.50±1.91 vs 41.50±6.46 (number/0.1mm2)]. Meanwhile c-myc ASODN induced more apoptotic cells than the control group(P<0.0001). c-myc protein expression was weak positive or negative in treated group and positive in control group.Conclusion c-myc ASODN can induce smooth muscle cells apoptosis after stenting in normal rabbit carotid arteries,and it can be used to prevent in-stent restenosis.

  2. The Max b-HLH-LZ can transduce into cells and inhibit c-Myc transcriptional activities.

    Science.gov (United States)

    Montagne, Martin; Beaudoin, Nicolas; Fortin, David; Lavoie, Christine L; Klinck, Roscoe; Lavigne, Pierre

    2012-01-01

    The inhibition of the functions of c-Myc (endogenous and oncogenic) was recently shown to provide a spectacular therapeutic index in cancer mouse models, with complete tumor regression and minimal side-effects in normal tissues. This was achieved by the systemic and conditional expression of omomyc, the cDNA of a designed mutant of the b-HLH-LZ of c-Myc named Omomyc. The overall mode of action of Omomyc consists in the sequestration of Max and the concomitant competition of the Omomyc/Max complex with the endogenous c-Myc/Max heterodimer. This leads to the inhibition of the transactivation of Myc target genes involved in proliferation and metabolism. While this body of work has provided extraordinary insights to guide the future development of new cancer therapies that target c-Myc, Omomyc itself is not a therapeutic agent. In this context, we sought to exploit the use of a b-HLH-LZ to inhibit c-Myc in a cancer cell line in a more direct fashion. We demonstrate that the b-HLH-LZ domain of Max (Max*) behaves as a bona fide protein transduction domain (PTD) that can efficiently transduce across cellular membrane via through endocytosis and translocate to the nucleus. In addition, we show that the treatment of HeLa cells with Max* leads to a reduction of metabolism and proliferation rate. Accordingly, we observe a decrease of the population of HeLa cells in S phase, an accumulation in G1/G0 and the induction of apoptosis. In agreement with these phenotypic changes, we show by q-RT-PCR that the treatment of HeLa cells with Max* leads to the activation of the transcription c-Myc repressed genes as well as the repression of the expression of c-Myc activated genes. In addition to the novel discovery that the Max b-HLH-LZ is a PTD, our findings open up new avenues and strategies for the direct inhibition of c-Myc with b-HLH-LZ analogs.

  3. The Max b-HLH-LZ can transduce into cells and inhibit c-Myc transcriptional activities.

    Directory of Open Access Journals (Sweden)

    Martin Montagne

    Full Text Available The inhibition of the functions of c-Myc (endogenous and oncogenic was recently shown to provide a spectacular therapeutic index in cancer mouse models, with complete tumor regression and minimal side-effects in normal tissues. This was achieved by the systemic and conditional expression of omomyc, the cDNA of a designed mutant of the b-HLH-LZ of c-Myc named Omomyc. The overall mode of action of Omomyc consists in the sequestration of Max and the concomitant competition of the Omomyc/Max complex with the endogenous c-Myc/Max heterodimer. This leads to the inhibition of the transactivation of Myc target genes involved in proliferation and metabolism. While this body of work has provided extraordinary insights to guide the future development of new cancer therapies that target c-Myc, Omomyc itself is not a therapeutic agent. In this context, we sought to exploit the use of a b-HLH-LZ to inhibit c-Myc in a cancer cell line in a more direct fashion. We demonstrate that the b-HLH-LZ domain of Max (Max* behaves as a bona fide protein transduction domain (PTD that can efficiently transduce across cellular membrane via through endocytosis and translocate to the nucleus. In addition, we show that the treatment of HeLa cells with Max* leads to a reduction of metabolism and proliferation rate. Accordingly, we observe a decrease of the population of HeLa cells in S phase, an accumulation in G1/G0 and the induction of apoptosis. In agreement with these phenotypic changes, we show by q-RT-PCR that the treatment of HeLa cells with Max* leads to the activation of the transcription c-Myc repressed genes as well as the repression of the expression of c-Myc activated genes. In addition to the novel discovery that the Max b-HLH-LZ is a PTD, our findings open up new avenues and strategies for the direct inhibition of c-Myc with b-HLH-LZ analogs.

  4. Long-range oncogenic activation of Igh-c-myc translocations by the Igh 3' regulatory region.

    Science.gov (United States)

    Gostissa, Monica; Yan, Catherine T; Bianco, Julia M; Cogné, Michel; Pinaud, Eric; Alt, Frederick W

    2009-12-10

    B-cell malignancies, such as human Burkitt's lymphoma, often contain translocations that link c-myc or other proto-oncogenes to the immunoglobulin heavy chain locus (IgH, encoded by Igh). The nature of elements that activate oncogenes within such translocations has been a long-standing question. Translocations within Igh involve DNA double-strand breaks initiated either by the RAG1/2 endonuclease during variable, diversity and joining gene segment (V(D)J) recombination, or by activation-induced cytidine deaminase (AID, also known as AICDA) during class switch recombination (CSR). V(D)J recombination in progenitor B (pro-B) cells assembles Igh variable region exons upstream of mu constant region (Cmu) exons, which are the first of several sets of C(H) exons ('C(H) genes') within a C(H) locus that span several hundred kilobases (kb). In mature B cells, CSR deletes Cmu and replaces it with a downstream C(H) gene. An intronic enhancer (iEmu) between the variable region exons and Cmu promotes V(D)J recombination in developing B cells. Furthermore, the Igh 3' regulatory region (Igh3'RR) lies downstream of the C(H) locus and modulates CSR by long-range transcriptional enhancement of C(H) genes. Transgenic mice bearing iEmu or Igh3'RR sequences fused to c-myc are predisposed to B lymphomas, demonstrating that such elements can confer oncogenic c-myc expression. However, in many B-cell lymphomas, Igh-c-myc translocations delete iEmu and place c-myc up to 200 kb upstream of the Igh3'RR. Here we address the oncogenic role of the Igh3'RR by inactivating it in two distinct mouse models for B-cell lymphoma with Igh-c-myc translocations. We show that the Igh3'RR is dispensable for pro-B-cell lymphomas with V(D)J recombination-initiated translocations, but is required for peripheral B-cell lymphomas with CSR-associated translocations. As the Igh3'RR is not required for CSR-associated Igh breaks or Igh-c-myc translocations in peripheral B-cell lymphoma progenitors, we conclude that

  5. c-Myc targeted regulators of cell metabolism in a transgenic mouse model of papillary lung adenocarcinoma.

    Science.gov (United States)

    Ciribilli, Yari; Singh, Prashant; Inga, Alberto; Borlak, Jürgen

    2016-10-04

    c-Myc's role in pulmonary cancer metabolism is uncertain. We therefore investigated c-Myc activity in papillary lung adenocarcinomas (PLAC). Genomics revealed 90 significantly regulated genes (> 3-fold) coding for cell growth, DNA metabolism, RNA processing and ribosomal biogenesis and bioinformatics defined c-Myc binding sites (TFBS) at > 95% of up-regulated genes. EMSA assays at 33 novel TFBS evidenced DNA binding activity and ChIP-seq data retrieved from public repositories confirmed these to be c-Myc bound. Dual-luciferase gene reporter assays developed for RNA-Terminal-Phosphate-Cyclase-Like-1(RCL1), Ribosomal-Protein-SA(RPSA), Nucleophosmin/Nucleoplasmin-3(NPM3) and Hexokinase-1(HK1) confirmed c-Myc functional relevance and ChIP assays with HEK293T cells over-expressing ectopic c-Myc demonstrated enriched c-Myc occupancy at predicted TFBS for RCL1, NPM3, HK1 and RPSA. Note, c-Myc recruitment on chromatin was comparable to the positive controls CCND2 and CDK4. Computational analyses defined master regulators (MR), i.e. heterogeneous nuclear ribonucleoprotein A1, nucleolin, the apurinic/apyrimidinic endonuclease 1, triosephosphate-isomerase 1, folate transporter (SLC19A1) and nucleophosmin to influence activity of up to 90% of PLAC-regulated genes. Their expression was induced by 3-, 3-, 6-, 3-, 11- and 7-fold, respectively. STRING analysis confirmed protein-protein-interactions of regulated genes and Western immunoblotting of fatty acid synthase, serine hydroxyl-methyltransferase 1, arginine 1 and hexokinase 2 showed tumor specific induction. Published knock down studies confirmed these proteins to induce apoptosis by disrupting neoplastic lipogenesis, by endorsing uracil accumulation and by suppressing arginine metabolism and glucose-derived ribonucleotide biosynthesis. Finally, translational research demonstrated high expression of MR and of 47 PLAC up-regulated genes to be associated with poor survival in lung adenocarcinoma patients (HR 3.2 p < 0.001) thus

  6. Pure invasive micropapillary carcinoma of the male breast: report of a rare case with C-MYC amplification.

    Science.gov (United States)

    Trépant, Anne-Laure; Hoorens, Anne; Noël, Jean-Christophe

    2014-12-01

    Male breast cancer is rare. The most common histological subtypes include invasive carcinoma "of no special type" and papillary carcinoma. Other variants, including pure micropapillary carcinoma, have been described as well but are extremely rare. Pure micropapillary carcinoma has been recently characterized by a C-MYC gene amplification in women. We report here, occurring in a 73-year-old man, the first case of pure micropapillary carcinoma with amplification of the C-MYC gene. Copyright © 2014 Elsevier GmbH. All rights reserved.

  7. c-Myc modulates glucose metabolism via regulation of miR-184/PKM2 pathway in clear-cell renal cell carcinoma.

    Science.gov (United States)

    Huang, Jiwei; Kong, Wen; Zhang, Jin; Chen, Yonghui; Xue, Wei; Liu, Dongming; Huang, Yiran

    2016-10-01

    Renal cell carcinoma (RCC) is one of the most malignant tumors worldwide. Among all subtypes of RCC, clear-cell RCC (ccRCC) is the most common and aggressive one. The difficulty in overcoming resistance of traditional treatment is a threat for ccRCC therapies. Therefore, to understand the mechanism that underlies ccRCC progression is critical for new drug development. In the present study, we identified that miR-184 could be downregulated by c-Myc, which is different from the standard opinion that c-Myc is a target of miR-184. Overexpression of pre-miR-184 changed the metabolic and proliferation features of ccRCC cells by reducing cell glucose consumption, lactate production and cell proliferation. Further analysis by computer bioinformatics revealed that PKM2 is a target of miR-184. Both PKM2 mRNA and protein were significantly affected by addition of miR-184. Importantly, the PKM2 expression level was indeed increased in ccRCC samples, which is totally reverse compared to the decreased miR-184 expression level. Interestingly, we found that when PKM2 was knocked down in ccRCC cells, the rapid proliferation, high glucose consumption and high lactate production were all clearly inhibited, which indicates metabolic reprogramming and cancer progression blocking the in ccRCC cells. Our findings shed new light on ccRCC molecular study and provide a new and solid basis for developing ccRCC therapy.

  8. Oridonin induces apoptosis and senescence in colorectal cancer cells by increasing histone hyperacetylation and regulation of p16, p21, p27 and c-myc

    Directory of Open Access Journals (Sweden)

    Zhao Ying-Zheng

    2010-11-01

    Full Text Available Abstract Background Oridonin, a tetracycline diterpenoid compound, has the potential antitumor activities. Here, we evaluate the antitumor activity and action mechanisms of oridonin in colorectal cancer. Methods Effects of oridonin on cell proliferation were determined by using a CCK-8 Kit. Cell cycle distribution was determined by flow cytometry. Apoptosis was examined by analyzing subdiploid population and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling assay. Senescent cells were determined by senescence-associated β-galactosidase activity analysis. Semi-quantitative RT-PCR was used to examine the changes of mRNA of p16, p21, p27 and c-myc. The concomitant changes of protein expression were analyzed with Western blot. Expression of AcH3 and AcH4 were examined by immunofluorescence staining and Western blots. Effects of oridonin on colony formation of SW1116 were examined by Soft Agar assay. The in vivo efficacy of oridonin was detected using a xenograft colorectal cancer model in nude mice. Results Oridonin induced potent growth inhibition, cell cycle arrest, apoptosis, senescence and colony-forming inhibition in three colorectal cancer cell lines in a dose-dependent manner in vitro. Daily i.p. injection of oridonin (6.25, 12.5 or 25 mg/kg for 28 days significantly inhibited the growth of SW1116 s.c. xenografts in BABL/C nude mice. With western blot and reverse transcription-PCR, we further showed that the antitumor activities of oridonin correlated with induction of histone (H3 and H4 hyperacetylation, activation of p21, p27 and p16, and suppression of c-myc expression. Conclusion Oridonin possesses potent in vitro and in vivo anti-colorectal cancer activities that correlated with induction of histone hyperacetylation and regulation of pathways critical for maintaining growth inhibition and cell cycle arrest. Therefore, oridonin may represent a novel therapeutic option in colorectal cancer treatment.

  9. Bromodichloromethane induces cell proliferation in different tissues of male F344 rats by suppression of E-cadherin expression via hypermethylation or transcriptional activation of c-myc and cyclin D1.

    Science.gov (United States)

    Liao, Jing; Li, Xiao-Feng; Zhou, Shun-Chang; Luo, Yan; Liu, Ai-Lin; Lu, Wen-Qing

    2013-11-25

    The aim of this study was to investigate the mechanism of bromodichloromethane (BDCM) - induced cell proliferation in different tissues of male F344 rats. Rats were administered at doses of 0 and 100mg/kg/day BDCM dissolved in corn oil by gavage for 5 days/week for 1, 4, 8 and 12 weeks. Then the colon, kidney and liver were collected. No histologic lesions were observed in the colon of rats exposed to BDCM, while there were mild nephrotoxicity and marginal hepatotoxicity related to BDCM treatment. Moreover, BDCM enhanced cell proliferation in the colon and kidney but not in the liver. In colons, hypermethylation in E-cadherin promoter might be associated with inhibition of mRNA and protein expression after 12 weeks of BDCM exposure. In kidneys, BDCM decreased E-cadherin mRNA expression, accompanying with transcriptional activation of c-myc and cyclin D1. However, suppression of E-cadherin mRNA and protein expression occurred in the absence of significant changes in DNA methylation. Therefore, suppression of E-cadherin expression via hypermethylation or transcriptional activation of c-myc and cyclin D1 may be involved in BDCM-induced cell proliferation in different tissues of male F344 rats.

  10. KSRP modulation of GAP-43 mRNA stability restricts axonal outgrowth in embryonic hippocampal neurons.

    Directory of Open Access Journals (Sweden)

    Clark W Bird

    Full Text Available The KH-type splicing regulatory protein (KSRP promotes the decay of AU-rich element (ARE-containing mRNAs. Although KSRP is expressed in the nervous system, very little is known about its role in neurons. In this study, we examined whether KSRP regulates the stability of the ARE-containing GAP-43 mRNA. We found that KSRP destabilizes this mRNA by binding to its ARE, a process that requires the presence of its fourth KH domain (KH4. Furthermore, KSRP competed with the stabilizing factor HuD for binding to these sequences. We also examined the functional consequences of KSRP overexpression and knockdown on the differentiation of primary hippocampal neurons in culture. Overexpression of full length KSRP or KSRP without its nuclear localization signal hindered axonal outgrowth in these cultures, while overexpression of a mutant protein without the KH4 domain that has less affinity for binding to GAP-43's ARE had no effect. In contrast, depletion of KSRP led to a rise in GAP-43 mRNA levels and a dramatic increase in axonal length, both in KSRP shRNA transfected cells and neurons cultured from Ksrp(+/- and Ksrp(-/- embryos. Finally we found that overexpression of GAP-43 rescued the axonal outgrowth deficits seen with KSRP overexpression, but only when cells were transfected with GAP-43 constructs containing 3' UTR sequences targeting the transport of this mRNA to axons. Together, our results suggest that KSRP is an important regulator of mRNA stability and axonal length that works in direct opposition to HuD to regulate the levels of GAP-43 and other ARE-containing neuronal mRNAs.

  11. Codon Usage and 3' UTR Length Determine Maternal mRNA Stability in Zebrafish.

    Science.gov (United States)

    Mishima, Yuichiro; Tomari, Yukihide

    2016-03-17

    The control of mRNA stability plays a central role in regulating gene expression. In metazoans, the earliest stages of development are driven by maternally supplied mRNAs. The degradation of these maternal mRNAs is critical for promoting the maternal-to-zygotic transition of developmental programs, although the underlying mechanisms are poorly understood in vertebrates. Here, we characterized maternal mRNA degradation pathways in zebrafish using a transcriptome analysis and systematic reporter assays. Our data demonstrate that ORFs enriched with uncommon codons promote deadenylation by the CCR4-NOT complex in a translation-dependent manner. This codon-mediated mRNA decay is conditional on the context of the 3' UTR, with long 3' UTRs conferring resistance to deadenylation. These results indicate that the combined effect of codon usage and 3' UTR length determines the stability of maternal mRNAs in zebrafish embryos. Our study thus highlights the codon-mediated mRNA decay as a conserved regulatory mechanism in eukaryotes.

  12. A small RNA activates CFA synthase by isoform-specific mRNA stabilization.

    Science.gov (United States)

    Fröhlich, Kathrin Sophie; Papenfort, Kai; Fekete, Agnes; Vogel, Jörg

    2013-11-13

    Small RNAs use a diversity of well-characterized mechanisms to repress mRNAs, but how they activate gene expression at the mRNA level remains not well understood. The predominant activation mechanism of Hfq-associated small RNAs has been translational control whereby base pairing with the target prevents the formation of an intrinsic inhibitory structure in the mRNA and promotes translation initiation. Here, we report a translation-independent mechanism whereby the small RNA RydC selectively activates the longer of two isoforms of cfa mRNA (encoding cyclopropane fatty acid synthase) in Salmonella enterica. Target activation is achieved through seed pairing of the pseudoknot-exposed, conserved 5' end of RydC to an upstream region of the cfa mRNA. The seed pairing stabilizes the messenger, likely by interfering directly with RNase E-mediated decay in the 5' untranslated region. Intriguingly, this mechanism is generic such that the activation is equally achieved by seed pairing of unrelated small RNAs, suggesting that this mechanism may be utilized in the design of RNA-controlled synthetic circuits. Physiologically, RydC is the first small RNA known to regulate membrane stability.

  13. Mechanistic Target of Rapamycin (mTOR) Inhibition Synergizes with Reduced Internal Ribosome Entry Site (IRES)-mediated Translation of Cyclin D1 and c-MYC mRNAs to Treat Glioblastoma.

    Science.gov (United States)

    Holmes, Brent; Lee, Jihye; Landon, Kenna A; Benavides-Serrato, Angelica; Bashir, Tariq; Jung, Michael E; Lichtenstein, Alan; Gera, Joseph

    2016-07-01

    Our previous work has demonstrated an intrinsic mRNA-specific protein synthesis salvage pathway operative in glioblastoma (GBM) tumor cells that is resistant to mechanistic target of rapamycin (mTOR) inhibitors. The activation of this internal ribosome entry site (IRES)-dependent mRNA translation initiation pathway results in continued translation of critical transcripts involved in cell cycle progression in the face of global eIF-4E-mediated translation inhibition. Recently we identified compound 11 (C11), a small molecule capable of inhibiting c-MYC IRES translation as a consequence of blocking the interaction of a requisite c-MYC IRES trans-acting factor, heterogeneous nuclear ribonucleoprotein A1, with its IRES. Here we demonstrate that C11 also blocks cyclin D1 IRES-dependent initiation and demonstrates synergistic anti-GBM properties when combined with the mechanistic target of rapamycin kinase inhibitor PP242. The structure-activity relationship of C11 was investigated and resulted in the identification of IRES-J007, which displayed improved IRES-dependent initiation blockade and synergistic anti-GBM effects with PP242. Mechanistic studies with C11 and IRES-J007 revealed binding of the inhibitors within the UP1 fragment of heterogeneous nuclear ribonucleoprotein A1, and docking analysis suggested a small pocket within close proximity to RRM2 as the potential binding site. We further demonstrate that co-therapy with IRES-J007 and PP242 significantly reduces tumor growth of GBM xenografts in mice and that combined inhibitor treatments markedly reduce the mRNA translational state of cyclin D1 and c-MYC transcripts in these tumors. These data support the combined use of IRES-J007 and PP242 to achieve synergistic antitumor responses in GBM. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

  14. TATA-binding protein and the retinoblastoma gene product bind to overlapping epitopes on c-Myc and adenovirus E1A protein

    NARCIS (Netherlands)

    Hateboer, G.; Timmers, H.T.M.; Rustgi, A.K.; Billaud, Marc; Veer, L.J. Van 't; Bernards, R.A.

    1993-01-01

    Using a protein binding assay, we show that the amino-teminal 204 amino acids of the c-Myc protein interact di y with a key component of the basal p tdon factor TFID, the TATA box-binding protein (TBP). Essentialy the same region of the c-Myc protein alo binds the product of the retinoblatoma gene,

  15. Effects of an inducible anti-sense c-myc gene transfer in a drug-resistant human small-cell-lung-carcinoma cell line

    NARCIS (Netherlands)

    Van Waardenburg, R C; Meijer, C; Burger, H; Nooter, K; De Vries, E G; Mulder, N H; de Jong, Steven

    1997-01-01

    Small-cell-lung-cancer (SCLC) is characterized by rapid development of resistance to cytotoxic agents, such as cisplatin (cDDP) and anthracyclines. c-myc over-expression is one of the reported genetic alterations in this tumor. Amplification of the c-myc gene in this and other cancers is often corre

  16. [Evaluation of c-myc and CCNE2 amplification in breast cancer with quantitative multi-gene fluorescence in-situ hybridization].

    Science.gov (United States)

    Li, Zhishuang; Meng, Qingyong; Yu, Qiong; Zhou, Zhiqiang; Li, Li

    2014-07-01

    To investigate c-myc and CCNE2 gene amplifications and their relationship in breast cancer. Sixty-six infiltrating ductal breast carcinomas with foci of ductal carcinoma in situ components collected from January 2005 to December 2007 were selected for tissue microarray and quantitative multi-gene FISH for c-myc and CCNE2 gene amplification, and the relationship with the clinicopathologic features was analyzed. Of the 66 cases, 18 (27.3%) showed c-myc amplification and 23 (34.8%) showed CCNE2 amplification. A strong correlation was found between c-myc and CCNE2 amplification (P c-myc and CCNE2 amplifications were all aneuploidy, and were HER2 positive (P c-myc amplification also showed higher Ki-67 index (P C-myc and CCNE2 amplifications are common events in breast cancer, and they often coexist. C-myc and CCNE2 genes may play critical roles in the pathogenesis and development of breast cancer through unique and overlapping signaling pathways.

  17. c-Myc Enhances Sonic Hedgehog-Induced Medulloblastoma Formation from Nestin-Expressing Neural Progenitors in Mice

    Directory of Open Access Journals (Sweden)

    Ganesh Rao

    2003-05-01

    Full Text Available Medulloblastomas are malignant brain tumors that arise in the cerebella of children. The presumed cellsof-origin are undifferentiated precursors of granule neurons that occupy the external granule layer (EGL of the developing cerebellum. The overexpression of proteins that normally stimulate proliferation of neural progenitor cells may initiate medulloblastoma formation. Two known mitogens for neural progenitors are the c-Myc oncoprotein and Sonic hedgehog (Shh, a crucial determinant of embryonic pattern formation in the central nervous system. We modeled the ability of c-Myc and Shh to induce medulloblastoma in mice using the RCAS/tv-a system, which allows postnatal gene transfer and expression in a cell type-specific manner. We targeted the expression of Shh and c-Myc to nestin-expressing neural progenitor cells by injecting replication-competent ALV splice acceptor (RCAS vectors into the cerebella of newborn mice. Following injection with RCAS-Shh alone, 3/32 (9% mice developed medulloblastomas and 5/32 showed multifocal hyperproliferation of the EGL, possibly a precursor stage of medulloblastoma. Following injection with RCAS-Shh plus RCAS-Myc, 9/39 (23% mice developed medulloblastomas. We conclude that nestin-expressing neural progenitors, present in the cerebellum at birth, can act as the cells-of-origin for medulloblastoma, and that c-Myc cooperates with Shh to enhance tumorigenicity.

  18. c-Myc regulates proliferation and Fgf10 expression in airway smooth muscle after airway epithelial injury in mouse.

    Directory of Open Access Journals (Sweden)

    Thomas Volckaert

    Full Text Available During lung development, Fibroblast growth factor 10 (Fgf10, which is expressed in the distal mesenchyme and regulated by Wnt signaling, acts on the distal epithelial progenitors to maintain them and prevent them from differentiating into proximal (airway epithelial cells. Fgf10-expressing cells in the distal mesenchyme are progenitors for parabronchial smooth muscle cells (PSMCs. After naphthalene, ozone or bleomycin-induced airway epithelial injury, surviving epithelial cells secrete Wnt7b which then activates the PSMC niche to induce Fgf10 expression. This Fgf10 secreted by the niche then acts on a subset of Clara stem cells to break quiescence, induce proliferation and initiate epithelial repair. Here we show that conditional deletion of the Wnt target gene c-Myc from the lung mesenchyme during development does not affect proper epithelial or mesenchymal differentiation. However, in the adult lung we show that after naphthalene-mediated airway epithelial injury c-Myc is important for the activation of the PSMC niche and as such induces proliferation and Fgf10 expression in PSMCs. Our data indicate that conditional deletion of c-Myc from PSMCs inhibits airway epithelial repair, whereas c-Myc ablation from Clara cells has no effect on airway epithelial regeneration. These findings may have important implications for understanding the misregulation of lung repair in asthma and COPD.

  19. Somatic polyploidy is associated with the upregulation of c-MYC interacting genes and EMT-like signature.

    Science.gov (United States)

    Vazquez-Martin, Alejandro; Anatskaya, Olga V; Giuliani, Alessandro; Erenpreisa, Jekaterina; Huang, Sui; Salmina, Kristine; Inashkina, Inna; Huna, Anda; Nikolsky, Nikolai N; Vinogradov, Alexander E

    2016-11-15

    The dependence of cancer on overexpressed c-MYC and its predisposition for polyploidy represents a double puzzle. We address this conundrum by cross-species transcription analysis of c-MYC interacting genes in polyploid vs. diploid tissues and cells, including human vs. mouse heart, mouse vs. human liver and purified 4n vs. 2n mouse decidua cells. Gene-by-gene transcriptome comparison and principal component analysis indicated that c-MYC interactants are significantly overrepresented among ploidy-associated genes. Protein interaction networks and gene module analysis revealed that the most upregulated genes relate to growth, stress response, proliferation, stemness and unicellularity, as well as to the pathways of cancer supported by MAPK and RAS coordinated pathways. A surprising feature was the up-regulation of epithelial-mesenchymal transition (EMT) modules embodied by the N-cadherin pathway and EMT regulators from SNAIL and TWIST families. Metabolic pathway analysis also revealed the EMT-linked features, such as global proteome remodeling, oxidative stress, DNA repair and Warburg-like energy metabolism. Genes associated with apoptosis, immunity, energy demand and tumour suppression were mostly down-regulated. Noteworthy, despite the association between polyploidy and ample features of cancer, polyploidy does not trigger it. Possibly it occurs because normal polyploidy does not go that far in embryonalisation and linked genome destabilisation. In general, the analysis of polyploid transcriptome explained the evolutionary relation of c-MYC and polyploidy to cancer.

  20. The 5T mouse multiple myeloma model: Absence of c-myc oncogene rearrangement in early transplant generations

    NARCIS (Netherlands)

    Radl, J.; Punt, Y.A.; Enden-Vieveen, M.H.M. van den; Bentvelzen, P.A.J.; Bakkus, M.H.C.; Akker T., W. van den; Benner, R.

    1990-01-01

    Consistent chromosomal translocations involving the c-myc cellular oncogene and one of the three immunoglobulin loci are typical for human Burkitt's lymphoma, induced mouse plasmacytoma (MPC) and spontaneously arising rat immunocytoma (RIC). Another plasma cell malignancy, multiple myeloma (MM), ari

  1. Effects of c-myc oncogene modulation on differentiation of human small cell lung carcinoma cell lines

    NARCIS (Netherlands)

    Van Waardenburg, RCAM; Meijer, C; Pinto-Sietsma, SJ; De Vries, EGE; Timens, W; Mulder, NM

    1998-01-01

    Amplification and over-expression of oncogenes of the myc family are related to the prognosis of certain solid tumors such as small cell lung cancer (SCLC). For SCLC, c-myc is the oncogene most consistently found to correlate with the end stage behaviour of the tumour, in particular with survival af

  2. Rapid loss of intestinal crypts upon conditional deletion of the Wnt/Tcf-4 target gene c-Myc.

    NARCIS (Netherlands)

    Muncan, V.; Sansom, O.J.; Tertoolen, L.; Phesse, T.J.; Begthel, H.; Sancho, E.; Cole, A.M.; Gregorieff, A.; Alboran, I.M. de; Clevers, J.C.; Clarke, A.R.

    2006-01-01

    Inhibition of the mutationally activated Wnt cascade in colorectal cancer cell lines induces a rapid G1 arrest and subsequent differentiation. This arrest can be overcome by maintaining expression of a single Tcf4 target gene, the proto-oncogene c-Myc. Since colorectal cancer cells share many molecu

  3. Amino-terminal domains of c-myc and N-myc proteins mediate binding to the retinoblastoma gene product

    Science.gov (United States)

    Rustgi, Anil K.; Dyson, Nicholas; Bernards, Rene

    1991-08-01

    THE proteins encoded by the myc gene family are involved in the control of cell proliferation and differentiation, and aberrant expression of myc proteins has been implicated in the genesis of a variety of neoplasms1. In the carboxyl terminus, myc proteins have two domains that encode a basic domain/helix-loop-helix and a leucine zipper motif, respectively. These motifs are involved both in DNA binding and in protein dimerization2-5. In addition, myc protein family members share several regions of highly conserved amino acids in their amino termini that are essential for transformation6,7. We report here that an N-terminal domain present in both the c-myc and N-myc proteins mediates binding to the retinoblastoma gene product, pRb. We show that the human papilloma virus E7 protein competes with c-myc for binding to pRb, indicating that these proteins share overlapping binding sites on pRb. Furthermore, a mutant Rb protein from a human tumour cell line that carried a 35-amino-acid deletion in its C terminus failed to bind to c-myc. Our results suggest that c-myc and pRb cooperate through direct binding to control cell proliferation.

  4. Correlation of Epstein-Barr virus and its encoded proteins with Helicobacter pylori and expression of c-met and c-myc in gastric carcinoma

    Institute of Scientific and Technical Information of China (English)

    Bing Luo; Yun Wang; Xiao-Feng Wang; Yu Gao; Bao-Hua Huang; Peng Zhao

    2006-01-01

    EBV and H pylori infection. The c-met overexpression was significantly higher in the EBVaGC group than in the EBVnGC group. However,c-met and c-myc expression did not show significant difference between the two groups. Transcripts of EBNA1 were detected in all 13 EBVaGCs, while both EBNA2 and LMP1 mRNA were not detected. Six of the 13 cases exhibited BARF1 transcripts and 2 exhibited BHRF1 transcripts.CONCLUSION: The positivity of H pylori in EBVnGCs is higher than that of EBVaGCs, but no significant correlation is found between EBV infection andH pylori infection. H pylori-positive gastric carcinoma is predominant in antrum location, while EBVaGC has a tendency of predominance in cardia/body location.EBV infection is associated with c-met abnormal expression but not with c-myc protein in EBVaGC. C-met overexpression is not induced by LMP1. BARF1 and BHRF1 may play important roles in the tumorigenesis of EBVaGC through different pathways.

  5. Posttranscriptional control of Klebsiella pneumoniae nif mRNA stability by the nifL product.

    OpenAIRE

    1986-01-01

    Posttranscriptional control of nif mRNA stability was demonstrated by functional and chemical analyses, using specific probes for four nif transcripts. In the wild type, nif transcripts (except nifLA) were stable during derepression, with half-lives of approximately 30 min. They were dramatically destabilized by O2 or elevated temperature (41 degrees C) and to a lesser extent by NH4+. In contrast, the nifLA message was not particularly stable, and posttranscriptional control was not evident. ...

  6. Induction of endogenous telomerase (hTERT) by c-Myc in WI-38 fibroblasts transformed with specific genetic elements.

    Science.gov (United States)

    Casillas, Mark A; Brotherton, Scott L; Andrews, Lucy G; Ruppert, J Michael; Tollefsbol, Trygve O

    2003-10-16

    Elucidation of the mechanisms governing expression of the human telomerase reverse transcriptase (hTERT) is important for understanding cancer pathogenesis. Approximately 90% of tumors express hTERT, the major catalytic component of telomerase. Activation of telomerase is an early event, and high levels of this activity correlate with poor prognosis. Recent studies have shown that the transcription factors c-Myc and Mad1 activate and repress hTERT, respectively. It is not clear how these transcription factors compete for the same recognition sequence in the hTERT core promoter region. Studies have shown that the combined expression of SV40 large T antigen (T-Ag), hTERT, and H-Ras is able to transform human cells. In this study, we used a distinct human cell type, WI-38 fetal lung fibroblasts used extensively for senescence studies. We transduced cells with amphotropic retroviral constructs containing SV40 T antigen, hTERT, and activated H-ras. Transduced cells exhibited anchorage independence in soft agar and expressed increased levels of c-Myc and endogenous hTERT. These effects were observed by 25 population doublings (PDs) following the establishment of the neoplastic cell line. During the process of transformation, we observed a switch from Mad1/Max to c-Myc/Max binding to oligonucleotide sequences containing the hTERT promoter distal and proximal E-boxes. c-Myc can bind specifically to the hTERT promoter in vitro, indicating that c-Myc expression in tumors may account for the increased expression of hTERT observed in vivo. These findings indicate that the widely used model system of WI-38 fibroblasts can be employed for transformation studies using defined genetic elements and that the endogenous hTERT and c-Myc are induced in these cells during early tumorigenesis. Such studies should have important implications in the mechanisms of hTERT and c-Myc induction in the beginning stages of tumorigenesis and facilitate extension of these studies to novel models of

  7. Elevation of c-MYC Disrupts HLA Class II-mediated Immune Recognition of Human B-cell Tumors1

    Science.gov (United States)

    God, Jason M.; Cameron, Christine; Figueroa, Janette; Amria, Shereen; Hossain, Azim; Kempkes, Bettina; Bornkamm, Georg W.; Stuart, Robert K.; Blum, Janice S.; Haque, Azizul

    2014-01-01

    Elevated levels of the transcription factor c-myc are strongly associated with various cancers, and in particular B-cell lymphomas. While many of c-MYC’s functions have been elucidated, its effect on the presentation of antigen (Ag) through the HLA class II pathway has not previously been reported. This is an issue of considerable importance, given the low immunogenicity of many c-MYC-positive tumors. We report here that increased c-MYC expression has a negative effect on the ability of B-cell lymphomas to functionally present Ags/peptides to CD4+ T cells. This defect was associated with alterations in the expression of distinct co-factors as well as interactions of antigenic peptides with class II molecules required for the presentation of class II-peptide complexes and T cell engagement. Using early passage Burkitt’s lymphoma (BL) tumors and transformed cells, we show that compared to B-lymphoblasts, BL cells express decreased levels of the class II editor HLA-DM, lysosomal thiol-reductase GILT, and a 47kDa enolase-like protein. Functional Ag presentation was partially restored in BL cells treated with a c-MYC inhibitor, demonstrating the impact of this oncogene on Ag recognition. This restoration of HLA class II-mediated Ag presentation in early passage BL tumors/cells was linked to enhanced HLA-DM expression and a concurrent decrease in HLA-DO in BL cells. Taken together, these results reveal c-MYC exerts suppressive effects at several critical checkpoints in Ag presentation which contribute to the immunoevasive properties of BL tumors. PMID:25595783

  8. Wnt/β-catenin signaling regulates Helicoverpa armigera pupal development by up-regulating c-Myc and AP-4.

    Science.gov (United States)

    Chen, Wei; Xu, Wei-Hua

    2014-10-01

    Seasonally changing environmental conditions perceived by insect brains can be converted into hormonal signals that prompt insects to make a decision to develop or enter developmental arrest (diapause). Diapause is a complex physiological response, and many signaling pathways may participate in its regulation. However, little is known about these regulatory pathways. In this study, we cloned four genes related to the Wnt/β-catenin signaling pathway from Helicoverpa armigera, a pupal diapause species. Western blotting shows that expression of Har-Wnt1, Har-β-catenin, and Har-c-Myc are higher in non-diapause pupal brains than in diapause-destined brains. Har-Wnt1 can promote the accumulation of Har-β-catenin in the nucleus, and Har-β-catenin in turn increases the expression of Har-c-Myc. The blockage of Wnt/β-catenin signaling by the inhibitor XAV939 significantly down-regulates Har-β-catenin and Har-c-Myc expression and delays pupal development, suggesting that the Wnt/β-catenin pathway functions in insect development. Furthermore, Har-c-Myc binds to the promoter of Har-AP-4 and regulates its expression. It has been reported that Har-AP-4 activates diapause hormone (DH) expression and that DH up-regulates the growth hormone ecdysteroid for pupal development. Thus, pupal development is regulated by Wnt/β-catenin signaling through the pathway Wnt-β-catenin-c-Myc-AP-4-DH-ecdysteroid. In contrast, the down-regulation of Wnt/β-catenin signaling is likely to induce insects to enter diapause.

  9. Endoglin inhibits ERK-induced c-Myc and cyclin D1 expression to impede endothelial cell proliferation

    Energy Technology Data Exchange (ETDEWEB)

    Pan, Christopher C.; Bloodworth, Jeffrey C. [Division of Pharmacology, Columbus, OH 43210 (United States); Mythreye, Karthikeyan [Duke University, Department of Medicine, Durham, NC 27708 (United States); Lee, Nam Y., E-mail: lee.5064@osu.edu [Division of Pharmacology, Columbus, OH 43210 (United States); Davis Heart and Lung Research Institute, Columbus, OH 43210 (United States)

    2012-08-03

    Highlights: Black-Right-Pointing-Pointer Endoglin inhibits ERK activation in endothelial cells. Black-Right-Pointing-Pointer Endoglin is a regulator of c-Myc and cyclin D1 expression. Black-Right-Pointing-Pointer {beta}-arrestin2 interaction with endoglin is required for ERK/c-Myc repression. Black-Right-Pointing-Pointer Endoglin impedes cellular proliferation by targeting ERK-induced mitogenic signaling. -- Abstract: Endoglin is an endothelial-specific transforming growth factor beta (TGF-{beta}) co-receptor essential for angiogenesis and vascular remodeling. Endoglin regulates a wide range of cellular processes, including cell adhesion, migration, and proliferation, through TGF-{beta} signaling to canonical Smad and Smad-independent pathways. Despite its overall pro-angiogenic role in the vasculature, the underlying mechanism of endoglin action is poorly characterized. We previously identified {beta}-arrestin2 as a binding partner that causes endoglin internalization from the plasma membrane and inhibits ERK signaling towards endothelial migration. In the present study, we examined the mechanistic role of endoglin and {beta}-arrestin2 in endothelial cell proliferation. We show that endoglin impedes cell growth through sustained inhibition of ERK-induced c-Myc and cyclin D1 expression in a TGF-{beta}-independent manner. The down-regulation of c-Myc and cyclin D1, along with growth-inhibition, are reversed when the endoglin/{beta}-arrestin2 interaction is disrupted. Given that TGF-{beta}-induced Smad signaling potently represses c-Myc in most cell types, our findings here show a novel mechanism by which endoglin augments growth-inhibition by targeting ERK and key downstream mitogenic substrates.

  10. K-RAS point mutation, and amplification of C-MYC and C-ERBB2 in colon adenocarcinoma.

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    Tadeusz Pawełczyk

    2004-10-01

    Full Text Available The routine multidisciplinary management of colon cancer is based mainly on tumor staging, histology, grading and vascular invasion. In this approach, important individual information derived from molecular characteristics of the tumor may be missed, especially since significant heterogeneity of molecular aberrations in cancer cells has been observed, and recognition of every of relationships between them may be of value. K-RAS, C-MYC and C-ERBB2 are protooncogenes taking part in carcinogenesis and tumor progression in the colon. They influence cell proliferation, differentiation and survival. K-RAS point mutation, as well as amplification of C-MYC and C-ERBB2 were searched in 84 primary colon adenocarcinomas resected with curative intent. Multiplex polymerase-chain reaction and restriction fragment length polymorphism were performed to assess codon 12 K-RAS point mutation. Amplification of C-MYC and C-ERBB2 genes was evaluated by densitometry after agarose gel separation of the respective multiplex PCR products. No relation was found among mutated and/or amplified genes, and between searched molecular aberrations and pathoclinical features. In multivariate analysis, nodal status appeared to be the only independent prognostic indicator. In colon adenocarcinoma, codon 12 K-RAS point mutation and amplification of C-MYC and C-ERBB2 seem to occur independently in the process of tumor progression. Amplification of C-ERBB2 tends to associate with more advanced stage of disease. Concomitant occurrence of codon 12 K-RAS mutation, C-MYC and C-ERBB2 amplification was of no prognostic value in respect to survival.

  11. A novel role for c-Myc in G protein-coupled receptor kinase 4 (GRK4) transcriptional regulation in human kidney proximal tubule cells.

    Science.gov (United States)

    Gildea, John J; Tran, Hanh T; Van Sciver, Robert E; Bigler Wang, Dora; Carlson, Julia M; Felder, Robin A

    2013-05-01

    The G protein-coupled receptor kinase 4 (GRK4) negatively regulates the dopaminergic system by desensitizing the dopamine-1-receptor. The expressional control of GRK4 has not been reported, but here we show that the transcription factor c-Myc binds to the promoter of GRK4 and positively regulates GRK4 protein expression in human renal proximal tubule cells (RPTCs). Addition of phorbol esters to RPTCs not only increased c-Myc binding to the GRK4 promoter but also increased both phospho-c-Myc and GRK4 expression. The phorbol ester-mediated increase in GRK4 expression was completely blocked by the c-Myc inhibitor, 10074-G5, indicating that GRK4 is downstream of phospho-c-Myc. The autocrine production of angiotensin II (Ang II) in RPTCs increased the phosphorylation and activation of c-Myc and subsequently GRK4 expression. 3-Amino-4-thio-butyl sulfonate, an inhibitor of aminopeptidase A, increased RPTC secretion of Ang II. 3-Amino-4-thio-butyl sulfonate or Ang II increased the expression of both phospho-c-Myc and GRK4, which was blocked by 10074-G5. Blockade of the Ang II type 1 receptor with losartan decreased phospho-c-Myc and GRK4 expression. Both inhibition of c-Myc activity and blockade of Ang II type 1 receptor restored the coupling of dopamine-1-receptor to adenylyl cyclase stimulation in uncoupled RPTCs, whereas phorbol esters or Ang II caused the uncoupling of normally coupled RPTCs. We suggest that the Ang II type 1 receptor impairs dopamine-1-receptor function via c-Myc activation of GRK4. This novel pathway may be involved in the increase in blood pressure in hypertension that is mediated by increased activity of the renin-angiotensin system and decreased activity of the renal dopaminergic system.

  12. S-Adenosylmethionine Inhibits the Growth of Cancer Cells by Reversing the Hypomethylation Status of c-myc and H-ras in Human Gastric Cancer and Colon Cancer

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    Jin Luo, Yan-Ni Li, Fei Wang, Wei-Ming Zhang, Xin Geng

    2010-01-01

    Full Text Available A global DNA hypomethylation might activate oncogene transcription, thus promoting carcinogenesis and tumor development. S-Adenosylmethionine (SAM serves as a major methyl donor in biological transmethylation events. The object of this study is to explore the influence of SAM on the status of methylation at the promoter of the oncogenes c-myc, H-ras and tumor-suppressor gene p16 (INK4a, as well as its inhibitory effect on cancer cells. The results indicated that SAM treatment inhibited cell growth in gastric cancer cells and colon cancer cells, and the inhibition efficiency was significantly higher than that in the normal cells. Under standard growth conditions, C-myc and H-ras promoters were hypomethylated in gastric cancer cells and colon cancer cells. SAM treatment resulted in a heavy methylation of these promoters, which consequently downregulated mRNA and protein levels. In contrast, there was no significant difference in mRNA and protein levels of p16 (INK4a with and without SAM treatment. SAM can effectively inhibit the tumor cells growth by reversing the DNA hypomethylation on promoters of oncogenes, thus down-regulating their expression. With no influence on the expression of the tumor suppressor genes, such as P16, SAM could be used as a potential drug for cancer therapy.

  13. Detection of hTERC and c-MYC genes in cervical epithelial exfoliated cells for cervical cancer screening.

    Science.gov (United States)

    Li, Tian; Tang, Liangdan; Bian, Duhong; Jia, Ying; Huang, Xin; Zhang, Xinhua

    2014-05-01

    Cervical cancer is the principal cause of mortality due to cancer in women worldwide. New predictive markers may increase survival rates by improving the treatment of patients at a high risk for cancer. This study was carried out to investigate the amplification of human telomerase RNA component (hTERC) or/and c-MYC in cervical epithelial exfoliated cells for cervical carcinoma screening. We collected 171 specimens. including speciments from normal cervix, benign lesions, cervical intraepithelial neoplasia (CIN)1, CIN2 and CIN3, or carcinoma in situ, as well as invasive cervical squamous cell carcinoma. Fluorescence in situ hybridization (FISH) was performed to detect alterations in hTERC and c-MYC expression. We analyzed the area under the receiver operating characteristic (ROC) curve (AUC), as well as the sensitivity and specificity of single screening and conjoined screening. There was a trend toward an increasing amplification of 2 genes with the increasing severity of cervical lesions. ROC curve analysis demonstrated that the AUC values of the hTERC gene for the screening of different cervical lesions were >0.8. Compared with the hTERC gene, the AUC of the c-MYC gene for the screening of ≥CIN3 was >0.8 and the AUC for the screening of other cervical lesions was >0.7. For the screening of cervical lesions above the grade of benign lesions, cytological diagnosis was superior to the gene detection with significant differences. For the screening of cervical lesions >CIN1, there were no statistically significant differences (P>0.05) between the hTERC gene and cytological diagnosis, whereas the screening results of c-MYC detection and cytological diagnosis differed significantly (PCIN2 or >CIN3, the detection of hTERC and c-MYC genes and cytological diagnosis had similar screening results with no statistically significant differences (P>0.05). In conclusion, using FISH to detect the amplification of hTERC or/and c-MYC on cervical epithelial exfoliated cells may be

  14. Co-overexpression of bcl-2 and c-myc in uterine cervix carcinomas and premalignant lesions

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    Z. Protrka

    2011-03-01

    Full Text Available To establish the role of co-overexpression of bcl-2 and c-myc protooncogenes in uterine cervix carcinogenesis, we examined 138 tissue samples of low grade cervical squamous intraepithelial lesions (SIL, high grade SIL, portio vaginalis uteri (PVU carcinoma in situ and PVU carcinoma invasive, stage IA-IIA (study group and 36 samples without SIL or malignancy (control group. The expression of bcl-2 and c-myc was detected immunohistochemically using a monoclonal antibody. Fisher’s exact test (P<0.05 was used to assess statistical significance. Overexpression of bcl-2 was found to increase in direct relation to the grade of the cervical lesions. High sensitivity was of great diagnostic significance for the detection of these types of changes in the uterine cervix. On the basis of high predictive values it can be said that in patients with bcl-2 overexpression there is a great possibility that they have premalignant or malignant changes in the uterine cervix. Co-overexpression of bcl-2 and c-myc oncogenes was found only in patients with PVU invasive carcinoma (6/26-23.0%. Statistically significant difference was not found in the frequency of co-overexpression in patients with PVU invasive carcinoma in relation to the control group (Fisher’s test; P=0.064. The method's sensitivity of determining these oncogenes with the aim of detecting PVU invasive carcinoma was 23%, while specificity was 72.2%. On the basis of high predictive values (100%, speaking in statistical terms, it can be concluded that all patients with co-overexpression of bcl-2 and c-myc oncogenes will have PVU invasive carcinoma. We confirmed in our research that co-overexpression of bcl-2 and c-myc oncogenes was increased only in PVU invasive carcinoma. However, a more extensive series of samples and additional tests are required to establish the prognostic significance of bcl-2 and c-myc co-overexpression in cervical carcinogenesis.

  15. Mitochondrial structure, function and dynamics are temporally controlled by c-Myc.

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    J Anthony Graves

    Full Text Available Although the c-Myc (Myc oncoprotein controls mitochondrial biogenesis and multiple enzymes involved in oxidative phosphorylation (OXPHOS, the coordination of these events and the mechanistic underpinnings of their regulation remain largely unexplored. We show here that re-expression of Myc in myc-/- fibroblasts is accompanied by a gradual accumulation of mitochondrial biomass and by increases in membrane polarization and mitochondrial fusion. A correction of OXPHOS deficiency is also seen, although structural abnormalities in electron transport chain complexes (ETC are not entirely normalized. Conversely, the down-regulation of Myc leads to a gradual decrease in mitochondrial mass and a more rapid loss of fusion and membrane potential. Increases in the levels of proteins specifically involved in mitochondrial fission and fusion support the idea that Myc affects mitochondrial mass by influencing both of these processes, albeit favoring the latter. The ETC defects that persist following Myc restoration may represent metabolic adaptations, as mitochondrial function is re-directed away from producing ATP to providing a source of metabolic precursors demanded by the transformed cell.

  16. Combined use of nuclear phosphoprotein c-Myc and cellular phosphoprotein p53 for hepatocellular carcinoma detection in high-risk chronic hepatitis C patients.

    Science.gov (United States)

    Attallah, A M; El-Far, M; Abdelrazek, M A; Omran, M M; Attallah, A A; Elkhouly, A A; Elkenawy, H M; Farid, K

    2017-10-01

    Hepatocellular carcinoma (HCC) is a multistage process resulting from various genetic changes. We aimed to determine nuclear phosphoprotein c-Myc and cellular phosphoprotein p53 expression and to evaluate their importance in HCC diagnosis. One hundred and twenty chronic hepatitis C (CHC) patients (60 non-HCC CHC patients and 60 HCC patients who had a single small (c-Myc and p53 were identified in liver tissues and serum samples using immunostaining, western blot and ELISA. Immunohistochemical detection of c-Myc and p53 with monospecific antibodies revealed intense and diffuse cytoplasmic staining patterns. Accumulated mutant proteins, released from tumour cells into the extracellular serum, were detected at 62 KDa, for c-Myc, and 53 KDa, for p53, using western blotting. In contrast to alpha feto-protein, there was a significant increase (p c-Myc (86.7% vs. 6.7%) and p53 (78.3% vs. 8.3%) in the malignant vs. non-malignant patients. The parallel combination of c-Myc and p53 reach the absolute sensitivity (100%), for more accurate and reliable HCC detection (specificity was 87%). c-Myc and p53 are potential HCC diagnostic biomarkers, and convenient combinations of them could improve diagnostic accuracy of HCC.

  17. Decrease of miR-622 expression promoted the proliferation, migration and invasion of cholangiocarcinoma cells by targeting regulation of c-Myc.

    Science.gov (United States)

    Wu, Yi-Fei; Li, Zhuo-Ri; Cheng, Zhi-Qi; Yin, Xin-Min; Wu, Jin-Shu

    2017-09-26

    To explore the mechanism of miR-622 in regulating the proliferation, migration and invasion of cholangiocarcinoma (CCA) cells. Quantitative real-time PCR was conducted to measure the expression of miR-622 and c-Myc in CCA tissues and cell lines. Protein level of c-Myc was measured by Western blot. The effect of miR-622 on cell proliferation, migration and invasion was analyzed by MTT assay and Transwell chamber migration assay. Luciferase reporter assay was performed to measure the effect of miR-622 on c-Myc. miR-622 expression was downregulated in both CCA tissues and cell lines, while c-Myc expression was uregulated. Overexpression of miR-622 in CCA cells was statistically correlated with a decrease of cell proliferation, migration and invasion, while inhibition of miR-622 made an inverse result. We also proved c-Myc was identified as a target gene of miR-622 in CCA. Moreover, we found overexpression of c-Myc can strengthen the effects of miR-622 on the proliferation, migration and invasion of CCA cells. Decrease of miR-622 promotes the proliferation, migration and invasion of CCA cells by directly targeting c-Myc. Copyright © 2017. Published by Elsevier Masson SAS.

  18. Suppression of c-Myc induces apoptosis via an AMPK/mTOR-dependent pathway by 4-O-methyl-ascochlorin in leukemia cells.

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    Shin, Jae-Moon; Jeong, Yun-Jeong; Cho, Hyun-Ji; Magae, Junji; Bae, Young-Seuk; Chang, Young-Chae

    2016-05-01

    4-O-Methyl-ascochlorin (MAC) is a methylated derivative of the prenyl-phenol antibiotic ascochlorin, which was isolated from an incomplete fungus, Ascochyta viciae. Although the effects of MAC on apoptosis have been reported, the underlying mechanisms remain unknown. Here, we show that MAC promoted apoptotic cell death and downregulated c-Myc expression in K562 human leukemia cells. The effect of MAC on apoptosis was similar to that of 10058-F4 (a c-Myc inhibitor) or c-Myc siRNA, suggesting that the downregulation of c-Myc expression plays a role in the apoptotic effect of MAC. Further investigation showed that MAC downregulated c-Myc by inhibiting protein synthesis. MAC promoted the phosphorylation of AMP-activated protein kinase (AMPK) and inhibited the phosphorylation of mammalian target of rapamycin (mTOR) and its target proteins, including p70S6 K and 4E-BP-1. Treatment of cells with AICAR (an AMPK activator), rapamycin (an mTOR inhibitor), or mTOR siRNA downregulated c-Myc expression and induced apoptosis to a similar extent to that of MAC. These results suggest that the effect of MAC on apoptosis induction in human leukemia cells is mediated by the suppression of c-Myc protein synthesis via an AMPK/mTOR-dependent mechanism.

  19. The FUSE binding proteins FBP1 and FBP3 are potential c-myc regulators in renal, but not in prostate and bladder cancer

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    Meyer Hellmuth-Alexander

    2008-12-01

    Full Text Available Abstract Background The three far-upstream element (FUSE binding proteins (FBP1, FBP2, and FBP3 belong to an ancient family of single-stranded DNA binding proteins which are required for proper regulation of the c-myc proto-oncogene. Whereas it is known that c-myc alterations play a completely different role in various carcinomas of the urogenital tract, the relevance of FBPs is unclear. Methods FBP1, FBP3 and c-myc expression was studied in 105 renal cell, 95 prostate and 112 urinary bladder carcinomas by immunohistochemistry using tissue microarrays. Results High rates of FBP1 and FBP3 expression were observed in all cancer types. There was a concomitant up-regulation of FBP1 and FBP3 in renal cell and prostate carcinomas (p C-myc expression was detectable in 21% of prostate, 30% of renal and 34% of urothelial carcinomas. Interestingly, strong FBP1 and FBP3 expression was associated with c-myc up-regulation in clear cell renal cell carcinomas (p Conclusion The correlation between FBP1/FBP3, c-myc and high proliferation rate in renal cell carcinoma provides strong in vivo support for the suggested role of FBP1 and FBP3 as activators of c-myc. The frequent up-regulation of FBP1 and FBP3 in urothelial and prostate carcinoma suggests that FBPs also have an important function in gene regulation of these tumors.

  20. Chromatin dynamics at the hTERT promoter during transcriptional activation and repression by c-Myc and Mnt in Xenopus leavis oocytes.

    Science.gov (United States)

    Wahlström, Therese; Belikov, Sergey; Arsenian Henriksson, Marie

    2013-12-10

    The transcription factors c-Myc and Mnt regulate gene expression through dimerization with Max and binding to E-boxes in target genes. While c-Myc activates gene expression via recruitment of histone modifying complexes, Mnt acts as a transcriptional repressor. Here, we used the Xenopus leavis oocyte system to address the effect of c-Myc and Mnt on transcription and chromatin remodeling over the E-box region in the human telomerase reverse transcriptase (hTERT) promoter. As expected we found elevated and decreased levels of hTERT transcription upon exogenously expressed c-Myc/Max and Mnt/Max, respectively. In addition, we confirmed binding of these heterodimers to both E-boxes already enriched with H3K9ac and H4K16ac. These chromatin marks were further enhanced upon c-Myc/Max binding followed by increased DNA accessibility in the E-box region. In contrast, Mnt/Max inhibited Myc-induced transcription and mediated repression through complete chromatin condensation and deacetylation of H3K9 and H4K16 across the E-box region. Importantly, Mnt was able to counteract c-Myc mediated activation even when expressed at low levels, suggesting Mnt to act as a strong repressor by closing the chromatin structure. Collectively our data demonstrate that the balance between c-Myc and Mnt activity determines the transcriptional outcome of the hTERT promoter by modulation of the chromatin architecture.

  1. Estrogen Induces c-myc Gene Expression via an Upstream Enhancer Activated by the Estrogen Receptor and the AP-1 Transcription Factor

    Science.gov (United States)

    Wang, Chunyu; Mayer, Julie Ann; Mazumdar, Abhijit; Fertuck, Kirsten; Kim, Heetae; Brown, Myles

    2011-01-01

    c-myc oncogene is implicated in tumorigenesis of many cancers, including breast cancer. Although c-myc is a well-known estrogen-induced gene, its promoter has no estrogen-response element, and the underlying mechanism by which estrogen induces its expression remains obscure. Recent genome-wide studies by us and others suggested that distant elements may mediate estrogen induction of gene expression. In this study, we investigated the molecular mechanism by which estrogen induces c-myc expression with a focus on these distal elements. Estrogen rapidly induced c-myc expression in estrogen receptor (ER)-positive breast cancer cells. Although estrogen had little effect on c-myc proximal promoter activity, it did stimulate the activity of a luciferase reporter containing a distal 67-kb enhancer. Estrogen induction of this luciferase reporter was dependent upon both a half-estrogen response element and an activator protein 1 (AP-1) site within this enhancer, which are conserved across 11 different mammalian species. Small interfering RNA experiments and chromatin immunoprecipitation assays demonstrated the necessity of ER and AP-1 cross talk for estrogen to induce c-myc expression. TAM67, the AP-1 dominant negative, partially inhibited estrogen induction of c-myc expression and suppressed estrogen-induced cell cycle progression. Together, these results demonstrate a novel pathway of estrogen regulation of gene expression by cooperation between ER and AP-1 at the distal enhancer element and that AP-1 is involved in estrogen induction of the c-myc oncogene. These results solve the long-standing question in the field of endocrinology of how estrogen induces c-myc expression. PMID:21835891

  2. Protor-2 interacts with tristetraprolin to regulate mRNA stability during stress

    Science.gov (United States)

    Holmes, Brent; Artinian, Nicholas; Anderson, Lauren; Martin, Jheralyn; Masri, Janine; Cloninger, Cheri; Bernath, Andrew; Bashir, Tariq; Benavides-Serrato, Angelica; Gera, Joseph

    2011-01-01

    The A/U-rich RNA binding protein tristetraprolin (TTP) is an mRNA destabilizing factor which plays a role in the regulated turnover of many transcripts encoding proteins involved in immune function and cell growth control. TTP also plays a role in stress-induced destabilization of mRNAs. Here we report the interaction of TTP with a component of the mTORC2 kinase, Protor-2 (PRR5-L, protein Q6MZQ0/FLJ14213/CAE45978). Protor-2 is structurally similar to human PRR5 and has been demonstrated to bind mTORC2 via Rictor and/or Sin1 and may signal downstream events promoting apoptosis. Protor-2 dissociates from mTORC2 upon hyperactivation of the kinase and is not required for mTORC2 integrity or activity. We identified Protor-2 in a yeast two-hybrid screen as a TTP interactor using the C-terminal mRNA decay domain of TTP as bait. The interaction of Protor-2 with TTP was also confirmed in vivo in co-immunoprecipitation experiments and Protor-2 was also detected in immunoprecipitates of rictor. Protor-2 was shown to stimulate TTP-mediated mRNA turnover of several TTP-associated mRNAs (TNF-α, GM-CSF, IL-3 and COX-2) in Jurkat cells when overexpressed while the half-lives of transcripts which do not decay via a TTP-mediated mechanism were unaffected. Knockdown of Protor-2 via RNAi inhibited TTP-mediated mRNA turnover of these TTP-associated mRNAs and inhibited association of TTP with cytoplasmic stress granules (SG) or mRNA processing bodies (P-bodies) following induction of the integrated stress response. These results suggest that Protor-2 associates with TTP to accelerate TTP-mediated mRNA turnover and functionally links the control of TTP regulated mRNA stability to mTORC2 activity. PMID:21964062

  3. Anchoring of c-myc on nuclear matrix proteins in process of mouse thymic T lymphocyte proliferation induced by ConA

    Institute of Scientific and Technical Information of China (English)

    曾丛梅; 蔡树涛; 周凤兰; 张锦珠; 王平

    1996-01-01

    Isolation and characteriation of functional nudear matrix proteins involved in DNA anchoring and gene expression is one of the major subjects of current nudear matrix research. Southwestern blotting (DNA-protein hybridization) was applied to studying the anchoring of c-myc on the nudear matrix proteins in mouse thymic T lymphocytes. The results showed that c-myc bound to the lamin, p34 and p36 nudear matrix proteins specifically. In the process of mouse thymic PNA T lymphocytes proliferation induced by ConA, the anchoring of c-myc on p34 and p36 nudear matrix proteins changed dynamically.

  4. [Diffuse large B-cell lymphoma with concomitant c-MYC and BCL6 gene rearrangements with primary skin involvement: A case report and a review of literature].

    Science.gov (United States)

    Gabeeva, N G; Koroleva, D A; Belyaeva, A V; Chernova, N G; Kuzmina, L A; Sudarikov, A B; Obukhova, T N; Kovrigina, A M; Zvonkov, E E; Savchenko, V G

    2017-01-01

    Double-hit lymphoma (DHL) is a rare aggressive B-cell lymphoma with concomitant c-MYC, BCL2 or BCL6 gene rearrangements, which is characterized by the high frequency of extranodal lesions and by resistance to chemotherapy. The median survival does not exceed 18 months in patients with this disease. The majority of DHL is represented by с-MYC/BCL2 cases. The combination of c-MYC/BCL6 occurs rarely (5-8%). The paper describes a case of DHL with concomitant c-MYC and BCL6 gene rearrangements, which mimics diffuse large B-cell lymphoma, leg-type.

  5. Acinar-to-ductal metaplasia accompanies c-myc-induced exocrine pancreatic cancer progression in transgenic rodents.

    Science.gov (United States)

    Grippo, Paul J; Sandgren, Eric P

    2012-09-01

    Several important characteristics of exocrine pancreatic tumor pathogenesis remain incompletely defined, including identification of the cell of origin. Most human pancreatic neoplasms are ductal adenocarcinomas. However, acinar cells have been proposed as the source of some ductal neoplasms through a process of acinar-to-ductal metaplasia. The oncogenic transcription factor c-myc is associated with human pancreatic neoplasms. Transgenic mice overexpressing c-myc under control of acinar cell-specific elastase (Ela) gene regulatory elements not only develop acinar cell carcinomas but also mixed neoplasms that display both acinar-like neoplastic cells and duct-like neoplastic cells. In this report, we demonstrate that, first, c-myc is sufficient to induce acinar hyperplasia, though neoplastic lesions develop focally. Second, cell proliferation remains elevated in the neoplastic duct cell compartment of mixed neoplasms. Third, the proliferation/apoptosis ratio in cells from all lesion types remains constant, suggesting that differential regulation of these processes is not a feature of cancer progression in this model. Fourth, before the development of mixed neoplasms, there is transcriptional activation of the duct cell-specific cytokeratin-19 gene promoter in multicellular foci of amylase-positive acinar neoplasms. This observation provides direct evidence for metaplasia as the mechanism underlying development of ductal neoplastic cells within the context of an acinar neoplasm and suggests that the stimulus for this transformation acts over a multicellular domain or field within a neoplasm. Finally, focal ductal elements develop in some acinar cell carcinomas in Ela-c-myc transgenic rats, indicating that myc-associated acinar-to-ductal metaplasia is not restricted to the mouse.

  6. Targeting C-myc G-Quadruplex: Dual Recognition by Aminosugar-Bisbenzimidazoles with Varying Linker Lengths

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    Nihar Ranjan

    2013-11-01

    Full Text Available G-quadruplexes are therapeutically important biological targets. In this report, we present biophysical studies of neomycin-Hoechst 33258 conjugates binding to a G-quadruplex derived from the C-myc promoter sequence. Our studies indicate that conjugation of neomycin to a G-quadruplex binder, Hoechst 33258, enhances its binding. The enhancement in G-quadruplex binding of these conjugates varies with the length and composition of the linkers joining the neomycin and Hoechst 33258 units.

  7. Conserved features of cancer cells define their sensitivity of HAMLET-induced death; c-Myc and glycolysis

    Science.gov (United States)

    Storm, Petter; Puthia, Manoj Kumar; Aits, Sonja; Urbano, Alexander; Northen, Trent; Powers, Scott; Bowen, Ben; Chao, Yinxia; Reindl, Wolfgang; Lee, Do Yup; Sullivan, Nancy Liu; Zhang, Jianping; Trulsson, Maria; Yang, Henry; Watson, James; Svanborg, Catharina

    2014-01-01

    HAMLET is the first member of a new family of tumoricidal protein-lipid complexes that kill cancer cells broadly, while sparing healthy, differentiated cells. Many and diverse tumor cell types are sensitive to the lethal effect, suggesting that HAMLET identifies and activates conserved death pathways in cancer cells. Here we investigated the molecular basis for the difference in sensitivity between cancer cells and healthy cells. Using a combination of small hairpin RNA inhibition, proteomic and metabolomic technology we identified the c-Myc oncogene as one essential determinant of HAMLET sensitivity. Increased c-Myc expression levels promoted the sensitivity to HAMLET and shRNA knockdown of c-Myc suppressed the lethal response, suggesting that oncogenic transformation with c-Myc creates a HAMLET-sensitive phenotype. Furthermore, the HAMLET sensitivity was modified by the glycolytic state of the tumor cells. Glucose deprivation sensitized tumor cells to HAMLET-induced cell death and in the shRNA screen Hexokinase 1, PFKFB1 and HIF1α modified HAMLET sensitivity. Hexokinase 1 was shown to bind HAMLET in a protein array containing approximately 8000 targets and Hexokinase activity decreased within 15 minutes of HAMLET treatment, prior to morphological signs of tumor cell death. In parallel, HAMLET triggered rapid metabolic paralysis in carcinoma cells. The glycolytic machinery was modified and glycolysis was shifted towards the pentose phosphate pathway. Tumor cells were also shown to contain large amounts of oleic acid and its derivatives already after 15 minutes. The results identify HAMLET as a novel anti-cancer agent that kills tumor cells by exploiting unifying features of cancer cells such as oncogene-addiction or the Warburg effect. PMID:21643007

  8. Conserved features of cancer cells define their sensitivity to HAMLET-induced death; c-Myc and glycolysis.

    Science.gov (United States)

    Storm, P; Aits, S; Puthia, M K; Urbano, A; Northen, T; Powers, S; Bowen, B; Chao, Y; Reindl, W; Lee, D Y; Sullivan, N L; Zhang, J; Trulsson, M; Yang, H; Watson, J D; Svanborg, C

    2011-12-01

    HAMLET is the first member of a new family of tumoricidal protein-lipid complexes that kill cancer cells broadly, while sparing healthy, differentiated cells. Many and diverse tumor cell types are sensitive to the lethal effect, suggesting that HAMLET identifies and activates conserved death pathways in cancer cells. Here, we investigated the molecular basis for the difference in sensitivity between cancer cells and healthy cells. Using a combination of small-hairpin RNA (shRNA) inhibition, proteomic and metabolomic technology, we identified the c-Myc oncogene as one essential determinant of HAMLET sensitivity. Increased c-Myc expression levels promoted sensitivity to HAMLET and shRNA knockdown of c-Myc suppressed the lethal response, suggesting that oncogenic transformation with c-Myc creates a HAMLET-sensitive phenotype. Furthermore, HAMLET sensitivity was modified by the glycolytic state of tumor cells. Glucose deprivation sensitized tumor cells to HAMLET-induced cell death and in the shRNA screen, hexokinase 1 (HK1), 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase 1 and hypoxia-inducible factor 1α modified HAMLET sensitivity. HK1 was shown to bind HAMLET in a protein array containing ∼8000 targets, and HK activity decreased within 15 min of HAMLET treatment, before morphological signs of tumor cell death. In parallel, HAMLET triggered rapid metabolic paralysis in carcinoma cells. Tumor cells were also shown to contain large amounts of oleic acid and its derivatives already after 15 min. The results identify HAMLET as a novel anti-cancer agent that kills tumor cells by exploiting unifying features of cancer cells such as oncogene addiction or the Warburg effect.

  9. The Influence of Nano-apatite on c-myc and p53 Gene in the Hepatocellular Carcinoma

    Institute of Scientific and Technical Information of China (English)

    CHEN Jun; CAO Xianying; LI Shipu; HAN Yingchao; ZHANG Ran

    2005-01-01

    The influence mechanism of the nano-apatite on the human hepatocellular carcinoma in vitro was investigated. Using the homogeneous precipitation method, the nano-apatite was synthesized at room temperature, and it was characterized with transmission electron microscopy (TEM) and the Zataplus. The influence on the expression of the c-myc and p53 gene in the human hepatocellular carcinoma cell lines were tested with the TEM and hybridization in situ. The TEM and the Zataplus analyses show that the nano-apatite is distributed homogenously in size and needle-shaped sizes, which ranges from 67.5 nm to 88.3 nm. It is found that the nano-apatitet increases the volume of the human hepatocellular carcinoma cells, makes extensive cytoplasmic vacuolization, the mitochondria swelling, chromatin in nucleus dispersed partially and condensed around the nuclear membranes.The interspace in nuclear membranes were separated and even the cytoplasm dissolved. It is also found that the expression of the c-myc gene is inhibited, but the p53 is enhanced. The experimental results demonstrate that the nano-apatite enables the oncosis of the human hepatocellular carcinoma cells by down-regulation of the expression of the c-myc and up-regulation of the expression of the p53 in vitro.

  10. Primary structure and functional scFv antibody expression of an antibody against the human protooncogen c-myc.

    Science.gov (United States)

    Fuchs, P; Breitling, F; Little, M; Dübel, S

    1997-06-01

    The immunoglobulin heavy- and light-chain variable region (Vh and Vl) genes were isolated from Myc1-9E10 hybridoma cells, which secreted monoclonal antibody against human oncogen c-myc. The expression vector pOPE52-c-myc was constructed for the recombinant production in E. coli. A 30 kDa single chain fragment (scFv) expression product was found in the periplasmic space by SDS-PAGE and immunoblotting. A significant fraction was processed correctly as demonstrated with an antiserum recognizing the processed aminoterminus only. The specific binding of the scFv fragment to the peptide epitope of the maternal monoclonal antibody was demonstrated and the primary sequence of the variable regions was determined. Sequence comparison with previously published partial Vh and Vl sequences from this hybridoma cell line revealed a genetic heterogeneity for the light chain variable region. The potential use of this scFv as a new tool for detection and purification of tagged proteins, for adding costimulatory signals to the surface of cancer cells as well as for analyzing c-myc function in the living cell by cytoplasmic expression is discussed.

  11. Expression of p53 and C-myc genes and its clinical relevance in the hepatocellular carcinomatous and pericarcinomatous tissues

    Institute of Scientific and Technical Information of China (English)

    Zhao-Shan Niu; Bo-Kian Li; Mei Wang

    2002-01-01

    AIM: To investigate the possible roles of p53 and C-mycgenes in the primary hepatocellular carcinogenesis and therelationship between the liver hyperplastic nodule(LHN) andhepatocellular carcinoma(HCC).METHODS: The expression of p53 and C-myc genes wasdetected immunohist-ochemically in 73 and 60 cases of HCCand pericarcinomatous tissues, respectively .RESULTS: The positive expression of p53 in HCC wassignificantly higher than that in pericarcinomatous tissues(P<0.05). In pericarcinomatous tissues, the p53 expressionwas observed only in LHN, but not in liver cirrhosis (LC) andnormal liver tissues. The positive expression rate of C-mycin HCC or LHN was significantly higher than that in LC ornormal liver tissues (P<0.05 and P<0.01), however, nosignificant difference was found between HCC and LHN(P>0.05). The positive expression rate of p53 and C-myc inHCC was correlated with the histological differentiation, thatin the poorly differentiated was significantly higher than thatin well differentiated samples (P<0.05).CONCLUSION: The overexpression of p53 and C-myc genesmight play a role in the carcinogenesis of HCC; And LHNseems a preneoplastic lesion related to hepatocarcinogenesis;No evidence supports that LC contribute directly to thehepatocarcinogenesis.

  12. Proliferation and C-myc Gene Expression of Smooth Muscle Cells in Rabbit Carotid Artery after Stenting

    Institute of Scientific and Technical Information of China (English)

    张新霞; 崔长琮; 胡雪松; 魏文斌; 李松; 许香广

    2004-01-01

    Objectives To investigate the proliferation of smooth muscle cells (VSMCs) and the expression of c-myc gene in rabbit carotid arteries after stenting. Methods Platinium-Iridium stent were implanted into the right carotid arteries of 16 rabbits under vision. 7,14,30 and 90 days after the stenting procedure, morphological changes of VSMCs were observed under light and transmission electron microscope. The c-myc gene expression was detected by in situ hybridization (ISH) and immunohistochemical staining. Results 7 days after stenting, the phenotype of VSMCs changed from contractile to synthetic phenotype; there were a number of proliferative VSMCs in the neointima. At 14 and 30 days, there were synthetic and transitive VSMCs. At 90 days, the phenotype of VSMCs recovered to contractile phenotype.The ultrastructure of typical synthetic phenotype of VSMCs were round, containing a large amount of rough endoplasmic reticulum and mitochondria. Cmyc expression were positive both by ISH and immunohistochemical staining. Conclusions C-myc gene expression increases and closely relates to VSMCs proliferation after stenting. It may play an important role in the in-stent restenosis.

  13. c-Myc and AMPK Control Cellular Energy Levels by Cooperatively Regulating Mitochondrial Structure and Function.

    Directory of Open Access Journals (Sweden)

    Lia R Edmunds

    Full Text Available The c-Myc (Myc oncoprotein and AMP-activated protein kinase (AMPK regulate glycolysis and oxidative phosphorylation (Oxphos although often for different purposes. Because Myc over-expression depletes ATP with the resultant activation of AMPK, we explored the potential co-dependency of and cross-talk between these proteins by comparing the consequences of acute Myc induction in ampk+/+ (WT and ampk-/- (KO murine embryo fibroblasts (MEFs. KO MEFs showed a higher basal rate of glycolysis than WT MEFs and an appropriate increase in response to activation of a Myc-estrogen receptor (MycER fusion protein. However, KO MEFs had a diminished ability to increase Oxphos, mitochondrial mass and reactive oxygen species in response to MycER activation. Other differences between WT and KO MEFs, either in the basal state or following MycER induction, included abnormalities in electron transport chain function, levels of TCA cycle-related oxidoreductases and cytoplasmic and mitochondrial redox states. Transcriptional profiling of pathways pertinent to glycolysis, Oxphos and mitochondrial structure and function also uncovered significant differences between WT and KO MEFs and their response to MycER activation. Finally, an unbiased mass-spectrometry (MS-based survey capable of quantifying ~40% of all mitochondrial proteins, showed about 15% of them to be AMPK- and/or Myc-dependent in their steady state. Significant differences in the activities of the rate-limiting enzymes pyruvate kinase and pyruvate dehydrogenase, which dictate pyruvate and acetyl coenzyme A abundance, were also differentially responsive to Myc and AMPK and could account for some of the differences in basal metabolite levels that were also detected by MS. Thus, Myc and AMPK are highly co-dependent and appear to engage in significant cross-talk across numerous pathways which support metabolic and ATP-generating functions.

  14. C-Myc regulates substrate oxidation patterns during early pressure-overload hypertrophy

    Energy Technology Data Exchange (ETDEWEB)

    Ledee, Dolena R. [Seattle Children' s Research Inst., Seattle, WA (United States); Smith, Lincoln [Seattle Children' s Hospital, Seattle, WA (United States); Kajimoto, Masaki [Seattle Children' s Research Inst., Seattle, WA (United States); Bruce, Margaret [Seattle Children' s Research Inst., Seattle, WA (United States); Isern, Nancy G. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Environmental Molecular Sciences Lab. (EMSL); Xu, Chun [Seattle Children' s Research Inst., Seattle, WA (United States); Portman, Michael A. [Seattle Children' s Research Inst., Seattle, WA (United States); Olson, Aaron [Seattle Children' s Research Inst., Seattle, WA (United States)

    2013-11-26

    Pressure overload cardiac hypertrophy alters substrate metabolism. Prior work showed that myocardial inactivation of c-Myc (Myc) attenuated hypertrophy and decreased expression of glycolytic genes after aortic constriction. Accordingly, we hypothesize that Myc regulates substrate preferences for the citric acid cycle during pressure overload hypertrophy from transverse aortic constriction (TAC) and that these metabolic changes impact cardiac function and growth. To test this hypothesis, we subjected FVB mice with cardiac specific, inducible Myc inactivation (MycKO-TAC) and non-transgenic littermates (Cont-TAC) to transverse aortic constriction (n=7/group). A separate group underwent sham surgery (Sham, n=5). After two weeks, function was measured in isolated working hearts along with substrate fractional contributions to the citric acid cycle by using perfusate with 13C labeled mixed fatty acids, lactate, ketones and unlabeled glucose and insulin. Western blots were used to evaluate metabolic enzymes. Cardiac function was similar between groups after TAC although +dP/dT and -dP/dT trended towards improvement in MycKO-TAC versus Cont-TAC. Compared to Sham, Cont-TAC had increased free fatty acid fractional contribution with a concurrent decrease in unlabeled (presumably glucose) contribution. Myc inactivation (MycKO-TAC) inhibited these metabolic changes. Hypertrophy in general increased protein levels of PKM2; however this change was not linked to Myc status. Protein post-translation modification by O-GlcNAc was significantly greater in Cont-TAC versus both Sham and MycKO-TAC. In conclusion, Myc regulates substrate utilization during early pressure overload hypertrophy. Our results show that the metabolic switch during hypertrophy is not necessary to maintain cardiac function, but it may be important mechanism to promote cardiomyocyte growth. Myc also regulates protein O-GlcNAcylation during hypertrophy.

  15. Induction of human spermine oxidase SMO(PAOh1) is regulated at the levels of new mRNA synthesis, mRNA stabilization and newly synthesized protein.

    Science.gov (United States)

    Wang, Yanlin; Hacker, Amy; Murray-Stewart, Tracy; Fleischer, Jennifer G; Woster, Patrick M; Casero, Robert A

    2005-03-15

    The oxidation of polyamines induced by antitumour polyamine analogues has been associated with tumour response to specific agents. The human spermine oxidase, SMO(PAOh1), is one enzyme that may play a direct role in the cellular response to the antitumour polyamine analogues. In the present study, the induction of SMO(PAOh1) enzyme activity by CPENSpm [N1-ethyl-N11-(cyclopropyl)methyl-4,8,diazaundecane] is demonstrated to be a result of newly synthesized mRNA and protein. Inhibition of new RNA synthesis by actinomycin D inhibits both the appearance of SMO(PAOh1) mRNA and enzyme activity. Similarly, inhibition of newly synthesized protein with cycloheximide prevents analogue-induced enzyme activity. Half-life determinations indicate that stabilization of SMO(PAOh1) protein does not play a significant role in analogue-induced activity. However, half-life experiments using actinomycin D indicate that CPENSpm treatment not only increases mRNA expression, but also leads to a significant increase in mRNA half-life (17.1 and 8.8 h for CPENSpm-treated cells and control respectively). Using reporter constructs encompassing the SMO(PAOh1) promoter region, a 30-90% increase in transcription is observed after exposure to CPENSpm. The present results are consistent with the hypothesis that analogue-induced expression of SMO(PAOh1) is a result of increased transcription and stabilization of SMO(PAOh1) mRNA, leading to increased protein production and enzyme activity. These data indicate that the major level of control of SMO(PAOh1) expression in response to polyamine analogues exposure is at the level of mRNA.

  16. Investigation of miRNA Biology by Bioinformatic Tools and Impact of miRNAs in Colorectal Cancer: Regulatory Relationship of c-Myc and p53 with miRNAs

    Directory of Open Access Journals (Sweden)

    Yaguang Xi

    2007-01-01

    Full Text Available MicroRNAs (miRNAs are a class of small non-coding RNAs that mediate gene expression at the posttranscriptional and translational levels and have been demonstrated to be involved in diverse biological functions. Mounting evidence in recent years has shown that miRNAs play key roles in tumorigenesis due to abnormal expression of and mutations in miRNAs. High throughput miRNA expression profiling of several major tumor types has identified miRNAs associated with clinical diagnosis and prognosis of cancer treatment. Previously our group has discovered a novel regulatory relationship between tumor suppressor gene p53 with miRNAs expression and a number of miRNA promoters contain putative p53 binding sites. In addition, others have reported that c-myc can mediate a large number of miRNAs expression. In this review, we will emphasize algorithms to identify mRNA targets of miRNAs and the roles of miRNAs in colorectal cancer. In particular, we will discuss a novel regulatory relationship of miRNAs with tumor suppressor p53 and c-myc. miRNAs are becoming promising novel targets and biomarkers for future cancer therapeutic development and clinical molecular diagnosis.

  17. BRG1 and BRM function antagonistically with c-MYC in adult cardiomyocytes to regulate conduction and contractility.

    Science.gov (United States)

    Willis, Monte S; Holley, Darcy Wood; Wang, Zhongjing; Chen, Xin; Quintana, Megan; Jensen, Brian C; Tannu, Manasi; Parker, Joel; Jeyaraj, Darwin; Jain, Mukesh K; Wolfram, Julie A; Lee, Hyoung-Gon; Bultman, Scott J

    2017-04-01

    The contractile dysfunction that underlies heart failure involves perturbations in multiple biological processes ranging from metabolism to electrophysiology. Yet the epigenetic mechanisms that are altered in this disease state have not been elucidated. SWI/SNF chromatin-remodeling complexes are plausible candidates based on mouse knockout studies demonstrating a combined requirement for the BRG1 and BRM catalytic subunits in adult cardiomyocytes. Brg1/Brm double mutants exhibit metabolic and mitochondrial defects and are not viable although their cause of death has not been ascertained. To determine the cause of death of Brg1/Brm double-mutant mice, to test the hypothesis that BRG1 and BRM are required for cardiac contractility, and to identify relevant downstream target genes. A tamoxifen-inducible gene-targeting strategy utilizing αMHC-Cre-ERT was implemented to delete both SWI/SNF catalytic subunits in adult cardiomyocytes. Brg1/Brm double-mutant mice were monitored by echocardiography and electrocardiography, and they underwent rapidly progressive ventricular dysfunction including conduction defects and arrhythmias that culminated in heart failure and death within 3weeks. Mechanistically, BRG1/BRM repressed c-Myc expression, and enforced expression of a DOX-inducible c-MYC trangene in mouse cardiomyocytes phenocopied the ventricular conduction defects observed in Brg1/Brm double mutants. BRG1/BRM and c-MYC had opposite effects on the expression of cardiac conduction genes, and the directionality was consistent with their respective loss- and gain-of-function phenotypes. To support the clinical relevance of this mechanism, BRG1/BRM occupancy was diminished at the same target genes in human heart failure cases compared to controls, and this correlated with increased c-MYC expression and decreased CX43 and SCN5A expression. BRG1/BRM and c-MYC have an antagonistic relationship regulating the expression of cardiac conduction genes that maintain contractility

  18. c-Myc Transforms Human Mammary Epithelial Cells through Repression of the Wnt Inhibitors DKK1 and SFRP1▿ †

    Science.gov (United States)

    Cowling, Victoria H.; D'Cruz, Celina M.; Chodosh, Lewis A.; Cole, Michael D.

    2007-01-01

    c-myc is frequently amplified in breast cancer; however, the mechanism of myc-induced mammary epithelial cell transformation has not been defined. We show that c-Myc induces a profound morphological transformation in human mammary epithelial cells and anchorage-independent growth. c-Myc suppresses the Wnt inhibitors DKK1 and SFRP1, and derepression of DKK1 or SFRP1 reduces Myc-dependent transforming activity. Myc-dependent repression of DKK1 and SFRP1 is accompanied by Wnt target gene activation and endogenous T-cell factor activity. Myc-induced mouse mammary tumors have repressed SFRP1 and increased expression of Wnt target genes. DKK1 and SFRP1 inhibit the transformed phenotype of breast cancer cell lines, and DKK1 inhibits tumor formation. We propose a positive feedback loop for activation of the c-myc and Wnt pathways in breast cancer. PMID:17485441

  19. Identification of a c-Jun N-terminal kinase-2-dependent signal amplification cascade that regulates c-Myc levels in ras transformation

    DEFF Research Database (Denmark)

    Mathiasen, D.P.; Egebjerg, C.; Andersen, S.H.

    2012-01-01

    that is critical for ras transformation in murine embryonic fibroblasts. This cascade is coordinated by ERK and JNK2 MAPKs, whose Ras-mediated activation leads to the enhanced levels of three oncogenic transcription factors, namely, c-Myc, activating transcription factor 2 (ATF2) and ATF3, all of which...... that counteracts protein phosphatase 2A-mediated dephosphorylation of c-Myc. Here we show that JNK2 regulates Cip2a transcription via ATF2. ATF2 and c-Myc cooperate to activate the transcription of ATF3. Remarkably, not only ectopic JNK2, but also ectopic ATF2, CIP2A, c-Myc and ATF3 are sufficient to rescue...

  20. A re-emerging marker for prognosis in hepatocellular carcinoma: the add-value of fishing c-myc gene for early relapse.

    Science.gov (United States)

    Pedica, Federica; Ruzzenente, Andrea; Bagante, Fabio; Capelli, Paola; Cataldo, Ivana; Pedron, Serena; Iacono, Calogero; Chilosi, Marco; Scarpa, Aldo; Brunelli, Matteo; Tomezzoli, Anna; Martignoni, Guido; Guglielmi, Alfredo

    2013-01-01

    Hepatocellular carcinoma is one leading cause of cancer-related death and surgical resection is still one of the major curative therapies. Recently, there has been a major effort to find mechanisms involved in carcinogenesis and early relapse. c-myc gene abnormality is found in hepatocarcinogenesis. Our aim was to analyze the role of c-myc as prognostic factor in terms of overall survival and disease-free survival and to investigate if c-myc may be an important target for therapy. We studied sixty-five hepatocellular carcinomas submitted to surgical resection with curative intent. Size, macro-microvascular invasion, necrosis, number of nodules, grading and serum alfa-fetoprotein level were registered for all cases. We evaluated the c-myc aberrations by using break-apart FISH probes. Probes specific for the centromeric part of chromosome 8 and for the locus specific c-myc gene (8q24) were used to assess disomy, gains of chromosomes (polysomy due to polyploidy) and amplification. c-myc gene amplification was scored as 8q24/CEP8 > 2. Statistical analysis for disease-free survival and overall survival were performed. At molecular level, c-myc was amplified in 19% of hepatocellular carcinoma, whereas showed gains in 55% and set wild in 26% of cases. The 1- and 3-year disease-free survival and overall survival for disomic, polysomic and amplified groups were significantly different (p=0.020 and p=.018 respectively). Multivariate analysis verified that the AFP and c-myc status (amplified vs. not amplified) were significant prognostic factors for overall patients survival. c-myc gene amplification is significantly correlated with disease-free survival and overall survival in patients with hepatocellular carcinoma after surgical resection and this model identifies patients with risk of early relapse (≤12 months). We suggest that c-myc assessment may be introduced in the clinical practice for improving prognostication (high and low risk of relapse) routinely and may have

  1. Analysis of secretome changes uncovers an autocrine/paracrine component in the modulation of cell proliferation and motility by c-Myc.

    Science.gov (United States)

    Pocsfalvi, Gabriella; Votta, Giuseppina; De Vincenzo, Anna; Fiume, Immacolata; Raj, Delfin Albert Amal; Marra, Giancarlo; Stoppelli, Maria Patrizia; Iaccarino, Ingram

    2011-12-02

    Proteins secreted by cancer cells are a major component of tumor microenvironment. However, little is known on the impact of single oncogenic lesions on the expression of secreted proteins at early stages of tumor development. Because c-Myc overexpression is among the most frequent alterations in cancer, here we investigated the effect of sustained c-Myc expression on the secretome of a nontransformed human epithelial cell line (hT-RPE). By using a quantitative proteomic approach, we have identified 125 proteins in conditioned media of hT-RPE/MycER cells upon c-Myc induction. Analysis of the 49 proteins significantly down-regulated by c-Myc revealed a marked enrichment of factors associated with growth inhibition and cellular senescence. Accordingly, media conditioned by hT-RPE cells expressing c-Myc show an increased ability to sustain hT-RPE cellular proliferation/viability. We also find a marked down-regulation of several structural and regulatory components of the extracellular matrix (ECM), which correlates with an increased chemotactic potency of the conditioned media toward fibroblasts, a major cellular component of tumor stroma. In accordance with these data, the expression of the majority of the genes encoding proteins down-regulated in hT-RPE was significantly reduced also in colorectal adenomatous polyps, early tumors in which c-Myc is invariably overexpressed. These findings help to elucidate the significance of c-Myc overexpression at early stages of tumor development and uncover a remarkable autocrine/paracrine component in the ability of c-Myc to stimulate proliferation, sustain tumor maintenance, and modulate cell migration.

  2. Decoding c-Myc networks of cell cycle and apoptosis regulated genes in a transgenic mouse model of papillary lung adenocarcinomas.

    Science.gov (United States)

    Ciribilli, Yari; Singh, Prashant; Spanel, Reinhard; Inga, Alberto; Borlak, Jürgen

    2015-10-13

    The c-Myc gene codes for a basic-helix-loop-helix-leucine zipper transcription factor protein and is reported to be frequently over-expressed in human cancers. Given that c-Myc plays an essential role in neoplastic transformation we wished to define its activity in lung cancer and therefore studied its targeted expression to respiratory epithelium in a transgenic mouse disease model. Using histological well-defined tumors, transcriptome analysis identified novel c-Myc responsive cell cycle and apoptosis genes that were validated as direct c-Myc targets using EMSA, Western blotting, gene reporter and ChIP assays.Through computational analyses c-Myc cooperating transcription factors emerged for repressed and up-regulated genes in cancer samples, namely Klf7, Gata3, Sox18, p53 and Elf5 and Cebpα, respectively. Conversely, at promoters of genes regulated in transgenic but non-carcinomatous lung tissue enriched binding sites for c-Myc, Hbp1, Hif1 were observed. Bioinformatic analysis of tumor transcriptomic data revealed regulatory gene networks and highlighted mortalin and moesin as master regulators while gene reporter and ChIP assays in the H1299 lung cancer cell line as well as cross-examination of published ChIP-sequence data of 7 human and 2 mouse cell lines provided strong evidence for the identified genes to be c-Myc targets. The clinical significance of findings was established by evaluating expression of orthologous proteins in human lung cancer. Taken collectively, a molecular circuit for c-Myc-dependent cellular transformation was identified and the network analysis broadened the perspective for molecularly targeted therapies.

  3. Using a Novel Transgenic Mouse Model to Study c-Myc Oncogenic Pathway in Castration Resistance and Chemoresistance of Prostate Cancer

    Science.gov (United States)

    2015-10-01

    Oncogenic Pathway in Castration Resistance and Chemoresistance of Prostate Cancer 3 Annual Progress Report W81XWH-13-1-0162 Using a Novel...Transgenic Mouse Model to Study c-Myc Oncogenic Pathway in Castration Resistance and Chemoresistance of Prostate Cancer Feng Yang, Ph.D. Department of...AWARD NUMBER: W81XWH-13-1-0162 TITLE: Using a Novel Transgenic Mouse Model to Study c-Myc Oncogenic Pathway in Castration Resistance and

  4. Decoding c-Myc networks of cell cycle and apoptosis regulated genes in a transgenic mouse model of papillary lung adenocarcinomas

    Science.gov (United States)

    Ciribilli, Yari; Singh, Prashant; Spanel, Reinhard; Inga, Alberto; Borlak, Jürgen

    2015-01-01

    The c-Myc gene codes for a basic-helix-loop-helix-leucine zipper transcription factor protein and is reported to be frequently over-expressed in human cancers. Given that c-Myc plays an essential role in neoplastic transformation we wished to define its activity in lung cancer and therefore studied its targeted expression to respiratory epithelium in a transgenic mouse disease model. Using histological well-defined tumors, transcriptome analysis identified novel c-Myc responsive cell cycle and apoptosis genes that were validated as direct c-Myc targets using EMSA, Western blotting, gene reporter and ChIP assays. Through computational analyses c-Myc cooperating transcription factors emerged for repressed and up-regulated genes in cancer samples, namely Klf7, Gata3, Sox18, p53 and Elf5 and Cebpα, respectively. Conversely, at promoters of genes regulated in transgenic but non-carcinomatous lung tissue enriched binding sites for c-Myc, Hbp1, Hif1 were observed. Bioinformatic analysis of tumor transcriptomic data revealed regulatory gene networks and highlighted mortalin and moesin as master regulators while gene reporter and ChIP assays in the H1299 lung cancer cell line as well as cross-examination of published ChIP-sequence data of 7 human and 2 mouse cell lines provided strong evidence for the identified genes to be c-Myc targets. The clinical significance of findings was established by evaluating expression of orthologous proteins in human lung cancer. Taken collectively, a molecular circuit for c-Myc-dependent cellular transformation was identified and the network analysis broadened the perspective for molecularly targeted therapies. PMID:26427040

  5. Knockdown of c-Myc inhibits cell proliferation by negatively regulating the Cdk/Rb/E2F pathway in nasopharyngeal carcinoma cells.

    Science.gov (United States)

    Niu, Zhaoxia; Liu, Huaying; Zhou, Ming; Wang, Heran; Liu, Yukun; Li, Xiayu; Xiong, Wei; Ma, Jian; Li, Xiaoling; Li, Guiyuan

    2015-03-01

    The proto-oncogene c-Myc encodes a transcription factor that is involved in the regulation of cellular proliferation, differentiation, and apoptosis. Several studies indicate that the over-expression of c-Myc is a frequent genetic abnormality in nasopharyngeal carcinoma (NPC). Therefore, specifically reducing its level by genetic means in established NPC cell lines helps to better understand its role in the pathogenesis of NPC. In this study, for the first time, we successfully established and characterized NPC 5-8F cell line with stably suppressed c-Myc expression by employing a DNA-based RNA interference approach. The suppression of c-Myc resulted in reduced cell growth, colony formation, and cell cycle progression in 5-8F cells. In vivo tumor formation assays revealed that the knockdown of c-Myc reduced the tumorigenic potential of 5-8F cells in nude mice. At the molecular level, we found that the knockdown of c-Myc could decrease the expression of several critical molecules involved in the Cdk/Rb/E2F pathway, including CDK4, cyclin D1, CDK2, pRb, E2F3, and DP2, and significantly reduced the promoter activity of cyclin D1. Taken together, these findings provide valuable mechanistic insights into the role of c-Myc in nasopharyngeal carcinogenesis and suggest that the knockdown of c-Myc may be a potential therapeutic approach for the treatment of NPC. © The Author 2015. Published by ABBS Editorial Office in association with Oxford University Press on behalf of the Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences.

  6. Cloned origin of DNA replication in c-myc gene can function and be transmitted in transgenic mice in an episomal state.

    OpenAIRE

    Sudo, Katsuko; Ogata, Masaaki; Sato, Yoshinari; Iguchi-Ariga, Sanae M. M.; Ariga, Hiroyoshi

    1990-01-01

    The c-myc protein has recently been shown to interact with a region possessing putative origin of DNA replication and enhancer activities located 2 kb upstream of the c-myc gene itself. Transgenic mice were obtained by injecting constructs containing this region, termed pmyc(H-P), into fertilized mouse eggs. The transgenic elements were capable of efficient replication in all mouse tissues examined and were maintained in an episomal state even in highly differentiated cells. Moreover, pmyc(H-...

  7. The immunomodulatory benzodiazepine Bz-423 inhibits B-cell proliferation by targeting c-myc protein for rapid and specific degradation.

    Science.gov (United States)

    Sundberg, Thomas B; Ney, Gina M; Subramanian, Chitra; Opipari, Anthony W; Glick, Gary D

    2006-02-01

    Myc proteins regulate cell growth and are oncogenic in many cancers. Although these proteins are validated molecular anticancer targets, new therapies aimed at modulating myc have yet to emerge. A benzodiazepine (Bz-423) that was discovered in efforts to find new drugs for lupus was found recently to have antiproliferative effects on Burkitt's lymphoma cells. We now show that the basis for the antiproliferative effects of Bz-423 is the rapid and specific depletion of c-myc protein, which is coupled to growth-suppressing effects on key regulators of proliferation and cell cycle progression. c-Myc is depleted as a result of signals coupled to Bz-423 binding its molecular target, the oligomycin sensitivity-conferring protein subunit of the mitochondrial F(1)F(o)-ATPase. Bz-423 inhibits F(1)F(o)-ATPase activity, blocking respiratory chain function and generating superoxide, which at growth-inhibiting concentrations triggers proteasomal degradation of c-myc. Bz-423-induced c-myc degradation is independent of glycogen synthase kinase but is substantially blocked by mutation of the phosphosensitive residue threonine 58, which when phosphorylated targets c-myc for ubiquitination and subsequent proteasomal degradation. Collectively, this work describes a new lead compound, with drug-like properties, which regulates c-myc by a novel molecular mechanism that may be therapeutically useful.

  8. c-myc Gene Copy Number Variation in Cervical Exfoliated Cells Detected on Fluorescence in situ Hybridization for Cervical Cancer Screening.

    Science.gov (United States)

    Zhao, Wei-Hong; Hao, Min; Cheng, Xiao-Tong; Yang, Xin; Wang, Zhi-Lian; Cheng, Ke-Yan; Liu, Fang-Li; Bai, Yao-Xian

    2016-01-01

    This study assessed the clinical significance of c-myc gene copy number gain detected by fluorescence in situ hybridization (FISH) in the prediction of cervical intraepithelial neoplasia (CIN) progression. We retrospectively investigated 140 Thinprep cytologic test (TCT) specimens that were histopathologically diagnosed with various stages of cervical neoplasia or malignancy. The specimens were subjected to TCT, human papillomavirus (HPV) testing, and FISH analysis with a c-myc-specific probe. The diagnostic reliability of these methods in determining progression was assessed according to sensitivity, specificity, and κ coefficients. The gene copy number gain of c-myc was significantly higher in the cervical lesion of advanced histologic grade (p c-myc gene test and either the TCT or the HPV DNA test were 0.538 and 0.399, respectively (p c-myc oncogene could be a useful adjunct screening method for the early diagnosis of high-grade cervical lesions. Moreover, c-myc may be a new molecular biomarker for the early diagnosis of cervical lesion progression. © 2016 S. Karger AG, Basel.

  9. The Expression of Antibiotic Resistance Methyltransferase Correlates with mRNA Stability Independently of Ribosome Stalling.

    Science.gov (United States)

    Dzyubak, Ekaterina; Yap, M N

    2016-12-01

    Members of the Erm methyltransferase family modify 23S rRNA of the bacterial ribosome and render cross-resistance to macrolides and multiple distantly related antibiotics. Previous studies have shown that the expression of erm is activated when a macrolide-bound ribosome stalls the translation of the leader peptide preceding the cotranscribed erm Ribosome stalling is thought to destabilize the inhibitory stem-loop mRNA structure and exposes the erm Shine-Dalgarno (SD) sequence for translational initiation. Paradoxically, mutations that abolish ribosome stalling are routinely found in hyper-resistant clinical isolates; however, the significance of the stalling-dead leader sequence is largely unknown. Here, we show that nonsense mutations in the Staphylococcus aureus ErmB leader peptide (ErmBL) lead to high basal and induced expression of downstream ErmB in the absence or presence of macrolide concomitantly with elevated ribosome methylation and resistance. The overexpression of ErmB is associated with the reduced turnover of the ermBL-ermB transcript, and the macrolide appears to mitigate mRNA cleavage at a site immediately downstream of the ermBL SD sequence. The stabilizing effect of antibiotics on mRNA is not limited to ermBL-ermB; cationic antibiotics representing a ribosome-stalling inducer and a noninducer increase the half-life of specific transcripts. These data unveil a new layer of ermB regulation and imply that ErmBL translation or ribosome stalling serves as a "tuner" to suppress aberrant production of ErmB because methylated ribosome may impose a fitness cost on the bacterium as a result of misregulated translation.

  10. Stabilization of Clostridium perfringens collagenase mRNA by VR-RNA-dependent cleavage in 5' leader sequence.

    Science.gov (United States)

    Obana, Nozomu; Shirahama, Yu; Abe, Kimihiro; Nakamura, Kouji

    2010-09-01

    The small RNA (sRNA), VR-RNA that is directly regulated by the VirR/VirS two-component system, regulates many genes including toxin genes such as collagenase (colA) and phospholipase C (plc) in Clostridium perfringens. Although the VR-RNA 3' region is sufficient to regulate the colA and plc genes, the molecular mechanism of toxin gene regulation by VR-RNA remains unclear. Here, we found that colA mRNA is cleaved at position -79 and -78 from the A of the first codon (ATG) in the presence of VR-RNA. The processed transcripts were stable compared with longer intact transcripts. On the other hand, colA mRNA was labile in a VR-RNA-deficient strain, and processed transcripts were undetectable. The stability and processing of colA mRNA were restored by transformation of the 3' region of VR-RNA-expression vector. The 3' region of VR-RNA and colA mRNA had significant complementation and interacted in vitro. These results show that VR-RNA base pairs with colA mRNA and induces cleavage in the 5' untranslated region (UTR) of colA mRNA, which leads to the stabilization of colA mRNA and the activation of colA expression. © 2010 Blackwell Publishing Ltd.

  11. Three-dimensional imaging of the metabolic state of c-MYC-induced mammary tumor with the cryo-imager

    Science.gov (United States)

    Zhang, Zhihong; Liu, Qian; Luo, Qingming; Zhang, Min Z.; Blessington, Dana M.; Zhou, Lanlan; Chodosh, Lewis A.; Zheng, Gang; Chance, Britton

    2003-07-01

    This study imaged the metabolic state of a growing tumor and the relationship between energy metabolism and the ability of glucose uptake in whole tumor tissue with cryo-imaging at 77° K. A MTB/TOM mouse model, bearing c-MYC-induced mammary tumor, was very rapidly freeze-trapped 2 hrs post Pyro-2DG injection. The fluorescence signals of oxidized flavoprotein (Fp), reduced pyridine nucleotide (PN), pyro-2DG, and the reflection signal of deoxy-hemoglobin were imaged every 100 μm from the top surface to the bottom of the tumor sequentially, 9 sections in total. Each of the four signals was constructed into 3D images with Amira software. Both Fp and PN signals could be detected in the growing tumor regions, and a higher reduction state where was shown in the ratio images. The necrotic tumor regions displayed a very strong Fp signal and weak PN signal. In the bloody extravasation regions, Fp and PN signals were observably diminished. Therefore, the regions of high growth and necrosis in the tumor could be determined according to the Fp and PN signals. The content of deoxy-hemoglobin (Hb) in the tumor was positively correlated with the reduced PN signal. Pyro-2DG signal was only evident in the growing condition region in the tumor. Normalized 3D cross-correlation showed that Pyro-2DG signal was similar to the redox ratio. The results indicated that glucose uptake in the tumor was consistent with the redox state of the tumor. And both Pyro-2DG and mitochondrial NADH fluorescence showed bimodal histograms suggesting that the two population of c-MYC induced mammary tumor, one of which could be controlled by c-MYC transgene.

  12. Bufalin inhibits pancreatic cancer by inducing cell cycle arrest via the c-Myc/NF-κB pathway.

    Science.gov (United States)

    Liu, Xia; Xiao, Xiang-Yang; Shou, Qi-Yang; Yan, Jun-Feng; Chen, Long; Fu, Hui-Ying; Wang, Jian-Chao

    2016-12-04

    Bufalin, a cardiotonic steroid isolated from toad venom (bufo gargarizans Cantor or B. melanotictus Schneider), has widely demonstrated antitumor effects and exhibits potential antitumor activity in various human cancer cells lines. The main characteristic of cancers including pancreatic cancer is the ability of uncontrolled proliferation. The aim of this study is to clarify the underlying mechanism by which bufalin inhibits pancreatic cancer cell proliferation. The effect of bufalin on the suppression of tumor growth in vivo was studied in a bioluminescent mouse model generated using the pancreatic cancer cell line BxPC3-luc2 and the cytotoxicity was evaluated in BcPc3 and Sw1990 cells with MTT. Flow cytometry and western blotting analyses were utilized to detect the effect of bufalin on the cell cycle and to detect the cell cycle-related proteins, respectively. Then, a luciferase reporter assay was applied to screen the activity of potent transcription factors following bufalin exposure and their expression was detected by western blotting. Bufalin suppressed tumor growth in a bioluminescence mouse model generated using BxPC3-luc2 cells and inhibited cell proliferation in vitro through inducing cell cycle arrest at S phase. Bufalin treatment inhibited cyclin D1 and cyclin E1 expression and therefore increased expression of p27, a regulatory molecular that controls cell cycle transition from S to G2 phase. Furthermore, luciferase reporter screening studies revealed that bufalin inhibited the expression and activity of the transcription factors c-Myc and NF-κB, which might cause cell cycle arrest at S phase and the inhibition of cell proliferation. Taken together, our results indicate that bufalin can inhibit pancreatic cancer by targeting c-Myc, thus suggesting that the mechanism of c-Myc regulation by bufalin might be worthy of further study regarding its potential as a therapeutic target for pancreatic cancer treatment. Copyright © 2016 Elsevier Ireland Ltd

  13. The Escherichia coli antiterminator protein BglG stabilizes the 5' region of the bgl mRNA

    Indian Academy of Sciences (India)

    Abhilasha Gulati; S Mahadevan

    2001-06-01

    The -glucoside utilization (bgl) genes of Escherichia coli are positively regulated by the product of the bglG gene, which functions as an antiterminator by binding to specific sequences present within the bgl mRNA. BglG is inactivated by phosphorylation in the absence of -glucosides by BglF, the bgl-specific component of the phosphotransferase system (PTS). Here, we present evidence for an additional function for BglG, namely the stabilization of the 5— end of the bgl mRNA. Half-life measurements of the promoter-proximal region of the bgl mRNA indicate a five fold enhancement of stability in the presence of active (unphosphorylated) BglG. This enhancement is lost when the binding of BglG to mRNA is prevented by deletion of the binding site. Interestingly, stabilization by BglG does not extend to downstream sequences. The enhanced stability of the upstream sequences suggest that BglG remains bound to its target on the mRNA even after the downstream sequences have been degraded. Implications of these observations for the mechanism of positive regulation of the operon by BglG are discussed.

  14. Critical B-lymphoid cell intrinsic role of endogenous MCL-1 in c-MYC-induced lymphomagenesis

    OpenAIRE

    Grabow, S; Kelly, G L; Delbridge, A R D; Kelly, P N; Bouillet, P; Adams, J M; Strasser, A.

    2016-01-01

    Evasion of apoptosis is critical for tumorigenesis, and sustained survival of nascent neoplastic cells may depend upon the endogenous levels of pro-survival BCL-2 family members. Indeed, previous studies using gene-targeted mice revealed that BCL-XL, but surprisingly not BCL-2, is critical for the development of c-MYC-induced pre-B/B lymphomas. However, it remains unclear whether another pro-survival BCL-2 relative contributes to their development. MCL-1 is an intriguing candidate, because it...

  15. c-myc protein can be substituted for SV40 T antigen in SV40 DNA replication.

    OpenAIRE

    Iguchi-Ariga, Sanae M. M.; Itani, Teru; Yamaguchi, Masamitsu; Ariga, Hiroyoshi

    1987-01-01

    Replicating activity of SV40 origin-containing plasmid was tested in human cells as well as in monkey CosI cells. All the plasmids possessing SV40 ori sequences could replicate, even in the absence of SV40 T antigen, in human HL-60 and Raji cells which are expressing c-myc gene at high level. The copy numbers of the replicated plasmids in these human cells were 1/100 as high as in monkey CosI cells which express SV40 T antigen constitutively. Exactly the same plasmids as the transfected origi...

  16. Theabrownin Inhibits Cell Cycle Progression and Tumor Growth of Lung Carcinoma through c-myc-Related Mechanism

    Science.gov (United States)

    Zhou, Li; Wu, Feifei; Jin, Wangdong; Yan, Bo; Chen, Xin; He, Yingfei; Yang, Weiji; Du, Wenlin; Zhang, Qiang; Guo, Yonghua; Yuan, Qiang; Dong, Xiaoqiao; Yu, Wenhua; Zhang, Jin; Xiao, Luwei; Tong, Peijian; Shan, Letian; Efferth, Thomas

    2017-01-01

    Green tea, the fresh leaves of Camellia sinensis, is not only a health-promoting beverage but also a traditional Chinese medicine used for prevention or treatment of cancer, such as lung cancer. Theabrownin (TB) is the main fraction responsible for the medicinal effects of green tea, but whether it possesses anti-cancer effect is unknown yet. This study aimed to determine the in vitro and in vivo anti-lung cancer effect of TB and explore the underlying molecular mechanism, by using A549 cell line and Lewis lung carcinoma-bearing mice. In cellular experiment, MTT assay was performed to evaluate the inhibitory effect and IC50 values of TB, and flow cytometry was conducted to analyze the cell cycle progression affected by TB. In animal experiment, mice body mass, tumor incidence, tumor size and tumor weight were measured, and histopathological analysis on tumor was performed with Transferase dUTP nick-end labeling staining. Real time PCR and western blot assays were adopted to detect the expression of C-MYC associated genes and proteins for mechanism clarification. TB was found to inhibit A549 cell viability in a dose- and time-dependent manner and block A549 cell cycle at G0/G1 phase. Down-regulation of c-myc, cyclin A, cyclin D, cdk2, cdk4, proliferation of cell nuclear antigen and up-regulation of p21, p27, and phosphate and tension homolog in both gene and protein levels were observed with TB treatment. A c-myc-related mechanism was thereby proposed, since c-myc could transcriptionally regulate all other genes in its downstream region for G1/S transitions of cell cycle and proliferation of cancer cells. This is the first report regarding the anti-NSCLC effect and the underlying mechanism of TB on cell cycle progression and proliferation of A549 cells. The in vivo data verified the in vitro result that TB could significantly inhibit the lung cancer growth in mice and induce apoptosis on tumors in a dose-dependent manner. It provides a promising candidate of natural

  17. Polymorphisms cMyc-N11S and p27-V109G and breast cancer risk and prognosis

    Directory of Open Access Journals (Sweden)

    Briollais Laurent

    2007-06-01

    Full Text Available Abstract Background cMyc and p27 are key genes implicated in carcinogenesis. Whether polymorphisms in these genes affect breast cancer risk or prognosis is still unclear. In this study, we focus on a rare non-synonymous polymorphism in cMyc (N11S and a common polymorphism in p27 (V109G and determine their role in risk and prognosis using data collected from the Ontario Breast Cancer Family Registry. Methods Risk factor data was collected at baseline on a large group of women (cases = 1,115 and population-based controls = 710 and clinical data (including treatment and follow-up were collected prospectively by periodic review of medical records for a subset of cases (N = 967 for nearly a decade. A centralized pathology review was conducted. Unconditional logistic regression was used to determine the association of polymorphisms with breast cancer risk and the Cox proportional hazards model was used to determine their association with survival. Results Our results suggest that while cMyc-N11S can be considered a putatively functional polymorphism located in the N-terminal domain, it is not associated with risk, tumor characteristics or survival. The p27-G109 allele was associated with a modest protective effect in adjusted analyses and higher T stage. We found no evidence to suggest that p27-V109G alone or in combination with cMyc-N11S was associated with survival. Age at onset and first-degree family history of breast or ovarian cancer did not significantly modify the association of these polymorphisms with breast cancer risk. Conclusion Further work is recommended to understand the potential functional role of these specific non-synonymous amino acid changes and a larger, more comprehensive investigation of genetic variation in these genes (e.g., using a tagSNP approach in combination with other relevant genes is needed as well as consideration for treatment effects when assessing their potential role in prognosis.

  18. Clinical significance of hTERC and C-Myc genes amplification in a group of Egyptian patients with cancer cervix.

    Science.gov (United States)

    Eid, M M; Nossair, H M; Ismael, M T; Amira, G; Hosney, M M; Abdul Rahman, R

    2011-07-01

    Cervical cancer is the second most common cancer in women worldwide after breast cancer. Cervical cancer is a preventable disease. The implementation of cervical cancer screening programs has greatly decreased the morbidity and mortality, as precancerous lesions and early invasive cervical cancer could be detected and treated effectively. The detection of hTERC gene amplification was suggested as a possible diagnostic marker for use in routine cytological screening. The present study was designed to detect genomic gains of the hTERC and C-MYC genes using FISH technique and to investigate the relationship between genes amplification and the clinical data of the patients. The current study was carried out on twelve cases with cervical cancer at different grades (three cases were grade I, six cases were grade II and three cases were grade III). Interphase FISH analysis using LSI probe, Cervical Cancer probe hTERC (3q26) & C-MYC (8q24), was successfully performed on 12 patients with cancer cervix. Interphase FISH analysis revealed positive hTERC gene amplification in all cases of cancer cervix (100%). However C-MYC gene amplification was detected in four cases only (33.3%). Statistical analysis of the data revealed significant correlation between hTERC amplification and grading. Also, there was significant correlation between C-MYC amplification and grading and highly significant correlation between C-MYC amplification and hTERC amplification. On the other hand hTERC and C-MYC genes amplification showed an inverse correlation with the ages of the patients. The present study highlights the importance of using hTERC and C-MYC genes FISH probes for cases with cancer cervix or pre-malignant lesions as a sensitive technique. This method provides an easy and effective applicable approach which helps in the diagnosis and prognosis, as an increased copy number is associated with a more advanced grade that could be detected in the early stages of the disease.

  19. Gene expression profiles in primary pancreatic tumors and metastatic lesions of Ela-c-myc transgenic mice

    Directory of Open Access Journals (Sweden)

    Liao Dezhong J

    2008-01-01

    Full Text Available Abstract Background Pancreatic carcinoma usually is a fatal disease with no cure, mainly due to its invasion and metastasis prior to diagnosis. We analyzed the gene expression profiles of paired primary pancreatic tumors and metastatic lesions from Ela-c-myc transgenic mice in order to identify genes that may be involved in the pancreatic cancer progression. Differentially expressed selected genes were verified by semi-quantitative and quantitative RT-PCR. To further evaluate the relevance of some of the selected differentially expressed genes, we investigated their expression pattern in human pancreatic cancer cell lines with high and low metastatic potentials. Results Data indicate that genes involved in posttranscriptional regulation were a major functional category of upregulated genes in both primary pancreatic tumors (PT and liver metastatic lesions (LM compared to normal pancreas (NP. In particular, differential expression for splicing factors, RNA binding/pre-mRNA processing factors and spliceosome related genes were observed, indicating that RNA processing and editing related events may play critical roles in pancreatic tumor development and progression. High expression of insulin growth factor binding protein-1 (Igfbp1 and Serine proteinase inhibitor A1 (Serpina1, and low levels or absence of Wt1 gene expression were exclusive to liver metastatic lesion samples. Conclusion We identified Igfbp1, Serpina1 and Wt1 genes that are likely to be clinically useful biomarkers for prognostic or therapeutic purposes in metastatic pancreatic cancer, particularly in pancreatic cancer where c-Myc is overexpressed.

  20. The long non-coding RNA PARROT is an upstream regulator of c-Myc and affects proliferation and translation

    Science.gov (United States)

    Vučićević, Dubravka; Gehre, Maja; Dhamija, Sonam; Friis-Hansen, Lennart; Meierhofer, David; Sauer, Sascha; Ørom, Ulf Andersson

    2016-01-01

    Long non-coding RNAs are important regulators of gene expression and signaling pathways. The expression of long ncRNAs is dysregulated in cancer and other diseases. The identification and characterization of long ncRNAs is often challenging due to their low expression level and localization to chromatin. Here, we identify a functional long ncRNA, PARROT (Proliferation Associated RNA and Regulator Of Translation) transcribed by RNA polymerase II and expressed at a relatively high level in a number of cell lines. The PARROT long ncRNA is associated with proliferation in both transformed and normal cell lines. We characterize the long ncRNA PARROT as an upstream regulator of c-Myc affecting cellular proliferation and translation using RNA sequencing and mass spectrometry following depletion of the long ncRNA. PARROT is repressed during senescence of human mammary epithelial cells and overexpressed in some cancers, suggesting an important association with proliferation through regulation of c-Myc. With this study, we add to the knowledge of cytoplasmic functional long ncRNAs and extent the long ncRNA-Myc regulatory network in transformed and normal cells. PMID:27129154

  1. Target guided synthesis using DNA nano-templates for selectively assembling a G-quadruplex binding c-MYC inhibitor

    Science.gov (United States)

    Panda, Deepanjan; Saha, Puja; Das, Tania; Dash, Jyotirmayee

    2017-07-01

    The development of small molecules is essential to modulate the cellular functions of biological targets in living system. Target Guided Synthesis (TGS) approaches have been used for the identification of potent small molecules for biological targets. We herein demonstrate an innovative example of TGS using DNA nano-templates that promote Huisgen cycloaddition from an array of azide and alkyne fragments. A G-quadruplex and a control duplex DNA nano-template have been prepared by assembling the DNA structures on gold-coated magnetic nanoparticles. The DNA nano-templates facilitate the regioselective formation of 1,4-substituted triazole products, which are easily isolated by magnetic decantation. The G-quadruplex nano-template can be easily recovered and reused for five reaction cycles. The major triazole product, generated by the G-quadruplex inhibits c-MYC expression by directly targeting the c-MYC promoter G-quadruplex. This work highlights that the nano-TGS approach may serve as a valuable strategy to generate target-selective ligands for drug discovery.

  2. BRCA1 and c-Myc associate to transcriptionally repress psoriasin, a DNA damage-inducible gene.

    Science.gov (United States)

    Kennedy, Richard D; Gorski, Julia J; Quinn, Jennifer E; Stewart, Gail E; James, Colin R; Moore, Stephen; Mulligan, Karl; Emberley, Ethan D; Lioe, Tong F; Morrison, Patrick J; Mullan, Paul B; Reid, George; Johnston, Patrick G; Watson, Peter H; Harkin, D Paul

    2005-11-15

    Evidence is accumulating to suggest that some of the diverse functions associated with BRCA1 may relate to its ability to transcriptionally regulate key downstream target genes. Here, we identify S100A7 (psoriasin), S100A8, and S100A9, members of the S100A family of calcium-binding proteins, as novel BRCA1-repressed targets. We show that functional BRCA1 is required for repression of these family members and that a BRCA1 disease-associated mutation abrogates BRCA1-mediated repression of psoriasin. Furthermore, we show that BRCA1 and c-Myc form a complex on the psoriasin promoter and that BRCA1-mediated repression of psoriasin is dependent on functional c-Myc. Finally, we show that psoriasin expression is induced by the topoisomerase IIalpha poison, etoposide, in the absence of functional BRCA1 and increased psoriasin expression enhances cellular sensitivity to this chemotherapeutic agent. Therefore, we identified a novel transcriptional mechanism that is likely to contribute to BRCA1-mediated resistance to etoposide.

  3. Targeting c-Myc-activated genes with a correlation method: Detection of global changes in large gene expression network dynamics

    Science.gov (United States)

    Remondini, D.; O'Connell, B.; Intrator, N.; Sedivy, J. M.; Neretti, N.; Castellani, G. C.; Cooper, L. N.

    2005-01-01

    This work studies the dynamics of a gene expression time series network. The network, which is obtained from the correlation of gene expressions, exhibits global dynamic properties that emerge after a cell state perturbation. The main features of this network appear to be more robust when compared with those obtained with a network obtained from a linear Markov model. In particular, the network properties strongly depend on the exact time sequence relationships between genes and are destroyed by random temporal data shuffling. We discuss in detail the problem of finding targets of the c-myc protooncogene, which encodes a transcriptional regulator whose inappropriate expression has been correlated with a wide array of malignancies. The data used for network construction are a time series of gene expression, collected by microarray analysis of a rat fibroblast cell line expressing a conditional Myc-estrogen receptor oncoprotein. We show that the correlation-based model can establish a clear relationship between network structure and the cascade of c-myc-activated genes. PMID:15867157

  4. Oncogenic K-ras confers SAHA resistance by up-regulating HDAC6 and c-myc expression.

    Science.gov (United States)

    Wang, Qun; Tan, Rong; Zhu, Xin; Zhang, Yi; Tan, Zhiping; Su, Bing; Li, Yu

    2016-03-01

    Histone deacetylase inhibitors (HDIs) represent a new class of anticancer drugs. Suberoylanilide hydroxamic acid (SAHA), the first HDI approved for the treatment of cutaneous T cell lymphoma (CTCL), is currently being tested in clinical trials for other cancers. However, SAHA has been ineffective against solid tumors in many clinical trials. A better understanding of molecular mechanisms of SAHA resistance may provide the basis for improved patient selection and the enhancement of clinical efficacy. Here we demonstrate that oncogenic K-ras contributes to SAHA resistance by upregulating HDAC6 and c-myc expression. We find that the high levels of HDAC6 expression are associated with activated K-ras mutant in colon cancer patients. And expressions of HDAC6 and c-myc are increased in fibroblasts transformed with activated K-ras. Surprisingly, we find that activated K-ras transformed cells are more resistant to SAHA inhibition on cell growth and anchorage-independent colony formation. We show that a K-ras inhibitor sensitizes K-ras mutated lung cancer cells to SAHA induced growth inhibition. We also find that mutant K-ras induces HDAC6 expression by a MAP kinase dependent pathway. Our study suggests that combined treatment with SAHA and K-ras inhibitors may represent an effective strategy to overcome SAHA resistance.

  5. TMPRSS2-ERG fusion, a common genomic alteration in prostate cancer activates C-MYC and abrogates prostate epithelial differentiation.

    Science.gov (United States)

    Sun, C; Dobi, A; Mohamed, A; Li, H; Thangapazham, R L; Furusato, B; Shaheduzzaman, S; Tan, S-H; Vaidyanathan, G; Whitman, E; Hawksworth, D J; Chen, Y; Nau, M; Patel, V; Vahey, M; Gutkind, J S; Sreenath, T; Petrovics, G; Sesterhenn, I A; McLeod, D G; Srivastava, S

    2008-09-11

    The high prevalence of TMPRSS2-ERG rearrangements ( approximately 60%) in prostate cancer (CaP) leads to androgenic induction of the ETS-related gene (ERG) expression. However, the biological functions of ERG overexpression in CaP remain to be understood. ERG knockdown in TMPRSS2-ERG expressing CaP cells induced striking morphological changes and inhibited cell growth both in cell culture and SCID mice. Evaluation of the transcriptome and specific gene promoters in ERG siRNA-treated cells and investigation of gene expression signatures of human prostate tumors revealed ERG-mediated activation of C-MYC oncogene and the repression of prostate epithelial differentiation genes (PSA and SLC45A3/Prostein). Taken together, these data combining cell culture and animal models and human prostate tumors reveal that ERG overexpression in prostate tumor cells may contribute to the neoplastic process by activating C-MYC and by abrogating prostate epithelial differentiation as indicated by prostate epithelial specific markers.

  6. Expressions of beta-catenin, APC Protein, C-myc and Cyclin D1 in Ovarian Epithelial Tumor and Their Implication

    Institute of Scientific and Technical Information of China (English)

    LIN Xiao; LI Yu; MI Can

    2007-01-01

    Objective: To investigate the expressions of beta-catenin, protein APC (adenomatous polyposis coli protein), c-myc and cyclin D1 and their implication in ovarian epithelial tumor. Methods: Immunohistochemical staining with SP method was conducted to identify the expressions of beta-catenin, APC protein, c-myc and cyclin D1 in ovarian epithelial tumor in 48 cases. Results: The abnormal expression rate of beta-catenin in malignant and borderline ovarian epithelial tumors was higher than that in benign epithelial tumors (P<0.01). The expression rates of c-myc and cyclin-D1 in ovarian malignant and borderline epithelial tumors were higher than those in benign epithelial tumors too(P<0.05). The prevalence of APC protein positive expression in benign epithelial tumors were significantly greater than that in malignant epithelial tumors (P<0.05). A significant negative correlation was found between beta-catenin and APC protein in ovarian epithelial tumors; while a significant positive correlation was found between beta-catenin, c-myc and cyclin-D1 in ovarian epithelial tumor (P<0.05). Conclusion: The abnormal expressions of Beta-catenin, APC protein, c-myc and cyclin-D1 might be used to indicate the malignance transform of ovarian epithelial tumors.

  7. Critical Role of c-Myc in Acute Myeloid Leukemia Involving Direct Regulation of miR-26a and Histone Methyltransferase EZH2

    Science.gov (United States)

    Salvatori, Beatrice; Iosue, Ilaria; Djodji Damas, Nkerorema; Mangiavacchi, Arianna; Chiaretti, Sabina; Messina, Monica; Padula, Fabrizio; Guarini, Anna; Bozzoni, Irene; Fazi, Francesco; Fatica, Alessandro

    2011-01-01

    Increased expression or aberrant activation of c-Myc plays an important role in leukemogenesis. Here, we show that in acute myeloid leukemia (AML), c-Myc directly controls the expression of EZH2, a component of the Polycomb repressive complex 2, and miR-26a. miR-26a is downregulated in primary blasts from AML patients and, during myeloid differentiation of AML cells, is induced together with a decrease in c-Myc and Ezh2 levels. Previously, EZH2 was shown to be regulated by miR-26a at the translational levels in lymphomas. However, we demonstrate that in AML, the variation of EZH2 mainly depends on c-Myc transcriptional control. We also show that enforced expression of miR-26a in AML cells is able to inhibit cell cycle progression by downregulating cyclin E2 expression. In addition, increased levels of miR-26a potentiate the antiproliferative effects of 1,25-dihydroxyvitamin D3 (VitD) and stimulate myeloid differentiation. Our results identify new molecular targets of c-Myc in AML and highlight miR-26a attractiveness as a therapeutic target in leukemia. PMID:21901171

  8. Human RNA polymerase II associated factor 1 complex promotes tumorigenesis by activating c-MYC transcription in non-small cell lung cancer

    Energy Technology Data Exchange (ETDEWEB)

    Zhi, Xiuyi [Department of Thoracic Surgery, Xuanwu Hospital, Capital Medical University, Beijing, 100053 (China); Giroux-Leprieur, Etienne [ER2 GRC UPMC04 Theranoscan, Pierre et Marie Curie University, Tenon Hospital, 4 Rue de La Chine, 75020, Paris (France); Respiratory Diseases and Thoracic Oncology Department, Ambroise Pare Hospital – APHP, Versailles Saint Quentin en Yvelines University, 9 Avenue Charles de Gaulle, 92100, Boulogne-Billancourt (France); Wislez, Marie [ER2 GRC UPMC04 Theranoscan, Pierre et Marie Curie University, Tenon Hospital, 4 Rue de La Chine, 75020, Paris (France); Hu, Mu; Zhang, Yi [Department of Thoracic Surgery, Xuanwu Hospital, Capital Medical University, Beijing, 100053 (China); Shi, Huaiyin [Department of Pathology, Chinese PLA General Hospital, Fu-xing Road #28, Beijing, 100853 (China); Du, Kaiqi, E-mail: kaiqidu_zhejiang@163.com [Department of Cardiothoracic Surgery, Chinese People' s Armed Police Force, Zhejiang Corps Hospital, Jiaxing, Zhejiang Province (China); Wang, Lei, E-mail: leiwang_hebei@163.com [Department of Human Anatomy, Hebei Medical University, Hebei Province (China)

    2015-10-02

    Human RNA polymerase II (RNAPII)-associated factor 1 complex (hPAF1C) plays a crucial role in protein-coding gene transcription. Overexpression of hPAF1C has been implicated in the initiation and progression of various human cancers. However, the molecular pathways involved in tumorigenesis through hPAF1C remain to be elucidated. The current study suggested hPAF1C expression as a prognostic biomarker for early stage non-small cell lung cancer (NSCLC) and patients with low hPAF1C expression levels had significantly better overall survival. Furthermore, the expression of hPAF1C was found to be positively correlated with c-MYC expression in patient tumor samples and in cancer cell lines. Mechanistic studies indicated that hPAF1C could promote lung cancer cell proliferation through regulating c-MYC transcription. These results demonstrated the prognostic value of hPAF1C in early-stage NSCLC and the role of hPAF1C in the transcriptional regulation of c-MYC oncogene during NSCLC tumorigenesis. - Highlights: • hPAF1C expression is a prognostic biomarker for early stage non-small cell lung cancer. • The expression of hPAF1C was positively correlated with c-MYC in tumor samples of patients and in several NSCLC cell lines. • hPAF1C could promote lung cancer cell proliferation through regulating c-MYC transcription.

  9. Transcriptional regulation of microsomal prostaglandin E synthase 1 by the proto-oncogene, c-myc, in the pathogenesis of inflammation and cancer.

    Science.gov (United States)

    Ramanan, M; Pilli, V S; Aradhyam, G K; Doble, M

    2017-01-22

    Pro-inflammatory molecules play a key role in the progression of various types of cancers highlighting the importance of studying the pathways that regulate the inflammatory cytokine production. To this end, prostaglandins have been reported to correlate with exacerbated cancer phenotypes that may be prevented by using anti-inflammatory drugs in humans. To understand how the prostaglandin E synthase 1 (mPGES1) may be regulated we analyzed its promoter sequence and identified myc-binding sites. Functional validation was performed by mutating the sites that led to attenuated promoter activation of mPGES1. The known c-myc inhibitor (10058-F4) also blocked PGE2 activity, indicating the importance of c-Myc in PGE2 synthesis. Isocoumarin analogs were able to reduce the expressions of both c-myc as well as mPGES1 and also inhibit the production of PGE2. Based on these data and the well-established role of c-myc in oncogenesis, we have demonstrated an additional role of c-myc in exacerbating cancers via PGE2 production, which may provide a therapeutic opportunity to treat these diseases. Copyright © 2016 Elsevier Inc. All rights reserved.

  10. Effects of Low-Dose Bisphenol A on DNA Damage and Proliferation of Breast Cells: The Role of c-Myc.

    Science.gov (United States)

    Pfeifer, Daniella; Chung, Young Min; Hu, Mickey C-T

    2015-12-01

    Humans are exposed to low-dose bisphenol A (BPA) through plastic consumer products and dental sealants containing BPA. Although a number of studies have investigated the mammary gland effects after high-dose BPA exposure, the study findings differ. Furthermore, there has been a lack of mechanistic studies. The objective of this study was to investigate the effect and the mechanism of low-dose BPA in mammary gland cells. We evaluated DNA damage following BPA exposure using the comet assay and immunofluorescence staining, and used cell counting and three-dimensional cultures to evaluate effects on proliferation. We examined the expressions of markers of DNA damage and cell-cycle regulators by immunoblotting and performed siRNA-mediated gene silencing to determine the role of c-Myc in regulating BPA's effects. Low-dose BPA significantly promoted DNA damage, up-regulated c-Myc and other cell-cycle regulatory proteins, and induced proliferation in parallel in estrogen receptor-α (ERα)-negative mammary cells. Silencing c-Myc diminished these BPA-induced cellular events, suggesting that c-Myc is essential for regulating effects of BPA on DNA damage and proliferation in mammary cells. Low-dose BPA exerted c-Myc-dependent genotoxic and mitogenic effects on ERα-negative mammary cells. These findings provide significant evidence of adverse effects of low-dose BPA on mammary cells.

  11. Antiproliferative Effects of Cucurbitacin B in Breast Cancer Cells: Down-Regulation of the c-Myc/hTERT/Telomerase Pathway and Obstruction of the Cell Cycle

    Directory of Open Access Journals (Sweden)

    Suwit Duangmano

    2010-12-01

    Full Text Available Naturally occurring cucurbitacins have been shown to have anticancer, antimicrobial and anti-inflammatory activities. In this study, we determined the effects of cucurbitacin B extracted from the Thai herb Trichosanthes cucumerina L. on telomerase regulation in three human breast cancer cell lines (T47D, SKBR-3, and MCF-7 and a mammary epithelium cell line (HBL-100. Cell viability after treatment with cucurbitacin B, which is an active ingredient of this herb, was assessed. Telomeric Repeat Amplification Protocol (TRAP assays and RT-PCR (qualitative and realtime were performed to investigate activity of telomerase as well as expression of human telomerase reverse transcriptase (hTERT and c-Myc. The c-Myc protein level was also determined in SKBR-3 and HBL-100 cells. Our results show that the cucurbitacin B inhibits growth and telomerase activity in the three breast cancer cell lines and exerts an obvious inhibitory effect in the estrogen receptor (ER-negative breast cancer SKBR-3 cells. The expression of hTERT and c-Myc were also inhibited by cucurbitacin B, In addition, a clear reduction of c-Myc protein was observed after treatment in SKBR-3 cells even with a concentration of cucurbitacin B that was ten-times lower compared to the concentration used for HBL-100. Our findings imply that cucurbitacin B exerts an anticancer effect by inhibiting telomerase via down regulating both the hTERT and c-Myc expression in breast cancer cells.

  12. Upregulation of c-MYC in cis through a Large Chromatin Loop Linked to a Cancer Risk-Associated Single-Nucleotide Polymorphism in Colorectal Cancer Cells▿

    Science.gov (United States)

    Wright, Jason B.; Brown, Seth J.; Cole, Michael D.

    2010-01-01

    Genome-wide association studies have mapped many single-nucleotide polymorphisms (SNPs) that are linked to cancer risk, but the mechanism by which most SNPs promote cancer remains undefined. The rs6983267 SNP at 8q24 has been associated with many cancers, yet the SNP falls 335 kb from the nearest gene, c-MYC. We show that the beta-catenin-TCF4 transcription factor complex binds preferentially to the cancer risk-associated rs6983267(G) allele in colon cancer cells. We also show that the rs6983267 SNP has enhancer-related histone marks and can form a 335-kb chromatin loop to interact with the c-MYC promoter. Finally, we show that the SNP has no effect on the efficiency of chromatin looping to the c-MYC promoter but that the cancer risk-associated SNP enhances the expression of the linked c-MYC allele. Thus, cancer risk is a direct consequence of elevated c-MYC expression from increased distal enhancer activity and not from reorganization/creation of the large chromatin loop. The findings of these studies support a mechanism for intergenic SNPs that can promote cancer through the regulation of distal genes by utilizing preexisting large chromatin loops. PMID:20065031

  13. Correlation of chromosomal polysomy with overexpression of c-myc and c-erbB-2 in primary nasopharyngeal carcinoma: Tissue microarray study

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Many genes may be involved in nasopharyngeal carcinoma (NPC) development and progression. Several known oncogenes, including c-myc and c-erb-B2, have been shown to have structural alteration and aberrant expression in NPC. Here, we constructed a tissue microarray to determine the status of c-myc and c-erbB-2 oncogenes at the DNA and protein levels using interphase fluorescence in situ hybridization (FISH) and immunohistochemistry (IHC) and to define the diagnostic, prognostic importance of the genetic changes. Results showed that amplification of c-myc and c-erbB-2 was not found in NPC. Polysomy 8 and 17 were observed in 43%-50% and 20%-27% of NPC tumors, respectively. Overexpressions of c-myc and c-erbB-2 oncoproteins were detected in 53.6% and 54.5% cases of NPC with polysomy 8 and 17, respectively. There was no significant correlation between c-myc and c-erbB-2 staining and the clinical stage. But overexpression of c-erbB-2 was associated with polysomy 17 in NPC. These findings suggest that chromosomal polysomy, not gene amplification, may be partially responsible for the upregulated expression of c-erbB-2 oncogene in NPC.

  14. Local Delivery of C-myc Antisense Oligodeoxynucleotide by Gelatin Coated Platinium-Iridium Stent to Prevent Restenosis in a Normal Rabbit Carotid Artery

    Institute of Scientific and Technical Information of China (English)

    Zhang Xinxia; Wei Wenbin; Duan Wen; Xu Xiangguang; Hu Xuesong

    2005-01-01

    Objectives To investigate the feasibility and effect of local deliveryof c-myc antisense oligodeoxynucleotide (ASODN) by gelatin coated Platinium-Iridium stent to prevent restenosis in a normal rabbit carotid artery. Methods Gelatin coated Platinium-Iridium stent were implanted in the right carotid arteries of 32 rabbits under vision. Animals were randomized to the control group and the treated group receiving c-myc ASODN (n=16 respectively).7,14,30,90 days following the stenting procedure,morphometry for caculation of neointimal area and mean neointimal thickness were performed.The expression of c-myc protein was detected by immunohistochemical methods. Results 32 stents were successfully implanted into the right carotid arteries in 32 animals. Morphometric analysis showed that neointimal area and mean neointimal thickness siginificantly increased continuously up to 12 weeks after stent implantation,and at each time point ,neointimal area and mean neointimal thickness were siginificantly smaller in the treated group than control group. (P<0.001 ,respectively).c-myc protein expression was weak positive or negative in treated group and positive in control group. Conclusions Gelatin coated Platinium-Iridium stent mediated local delivery of c-myc ASODN is feasibility , and it can inhibit neointimal hyperplasia to prevent restenosis in a normal rabbit carotid artery.

  15. Altered expression of Bcl-2, c-Myc, H-Ras, K-Ras, and N-Ras does not influence the course of mycosis fungoides

    Science.gov (United States)

    Maj, Joanna; Jankowska-Konsur, Alina; Plomer-Niezgoda, Ewa; Sadakierska-Chudy, Anna

    2013-01-01

    Introduction Data about genetic alterations in mycosis fungoides (MF) are limited and their significance not fully elucidated. The aim of the study was to explore the expression of various oncogenes in MF and to assess their influence on the disease course. Material and methods Skin biopsies from 27 MF patients (14 with early MF and 13 with advanced disease) and 8 healthy volunteers were analyzed by real-time polymerase chain reaction (PCR) to detect Bcl-2, c-Myc, H-Ras, K-Ras and N-Ras expression. All PCR reactions were performed using an Applied Biosystems 7900HT Fast Real-Time PCR System and interpreted using Sequence Detection Systems software which utilizes the comparative delta Ct method. The level of mRNA was normalized to GAPDH expression. All data were analyzed statistically. Results All evaluated oncogenes were found to be expressed in the skin from healthy controls and MF patients. Bcl-2 (–4.2 ±2.2 vs. –2.2 ±1.1; p = 0.01), H-Ras (–3.0 ±3.3 vs. 0.6 ±2.6; p = 0.01) and N-Ras (–3.6 ±2.0 vs. –1.1 ±2.4; p = 0.03) were expressed at significantly lower levels in MF. No relationships between oncogene expression and disease stage, presence of distant metastases and survival were observed (p > 0.05 for all comparisons). Conclusions The pathogenic role and prognostic significance of analyzed oncogenes in MF seem to be limited and further studies are needed to establish better prognostic factors for patients suffering from MF. PMID:24273576

  16. CyclinA、C-myc在皮肤瘢痕及瘢痕癌组织中的表达及意义%Expressions and Significance of CyclinA and C-myc in Skin Scar and Skin Scar Carcinoma

    Institute of Scientific and Technical Information of China (English)

    郭瑞珍; 周开梅; 王燕

    2011-01-01

    目的 探讨CyclinA、C-myc在皮肤病理性瘢痕和瘢痕癌组织中的表达及意义.方法以病理性皮肤瘢痕、皮肤瘢痕癌组织为研究对象,以正常皮肤组织为对照.采用免疫组织化学(SP法)分别检测CyclinA、C-myc蛋白的表达,采用核酸分子原位杂交法检测CyclinA mRNA的表达,所有数据输入计算机后运用SPSS 16.0软件包进行统计学分析.结果 (1)CyclinA、CyclinA mRNA在正常皮肤和皮肤瘢痕上皮中的表达呈阴性或弱阳性,在瘢痕癌组织中呈强阳性.瘢痕癌组的表达(平均吸光度和阳性面积)与正常皮肤组及皮肤瘢痕组比较,差异均有统计学意义(P<0.01);但正常皮肤组与瘢痕组比较,差异无统计学意义(P>0.05).(2)C-myc蛋白在正常皮肤中的表达呈弱阳性,在皮肤瘢痕上皮中呈阳性,在瘢痕癌组织中呈强阳性.且两两比较差异均有统计学意义(P<0.05).(3)相关分析显示,在皮肤瘢痕癌中,CyclinA与CyclinA mRNA(r=0.766,P<0.01)、CyclinA与C-myc蛋白(r=0.804,P<0.01)的表达均呈正相关.结论(1)CyclinA及其mRNA、C-myc的高表达,可能与皮肤瘢痕癌的发生有关;(2)C-myc蛋白的高表达与皮肤瘢痕上皮癌变有相关性.(3)在瘢痕癌中CyclinA同时存在蛋白水平和基因水平的异常表达.%Objective To study the expressions and significance of CyclinA and C-myc in skin Scar and skin Scar Carcinoma. Methods We compared pathological skin scar tissues and skin scar carcinoma tissues with normal skin tissues. The expression of CyclinA and C-myc proteins were detected by the immu-nohistochemical method of SP. And the expression of CyclinA mRNA was detected by in situ hybridization. All data were input into the computer and statistically analyzed with SPSS (16. 0) software. Results (1) CyclinA and its mRNA showed strong positive expression in scar carcinoma tissues, negative or weakly positive expression in normal skin epidermis and pathological skin scar epithelium

  17. c-Myc-miR-29c-REV3L signalling pathway drives the acquisition of temozolomide resistance in glioblastoma.

    Science.gov (United States)

    Luo, Hui; Chen, Zhengxin; Wang, Shuai; Zhang, Rui; Qiu, Wenjin; Zhao, Lin; Peng, Chenghao; Xu, Ran; Chen, Wanghao; Wang, Hong-Wei; Chen, Yuanyuan; Yang, Jingmin; Zhang, Xiaotian; Zhang, Shuyu; Chen, Dan; Wu, Wenting; Zhao, Chunsheng; Cheng, Gang; Jiang, Tao; Lu, Daru; You, Yongping; Liu, Ning; Wang, Huibo

    2015-12-01

    Resistance to temozolomide poses a major clinical challenge in glioblastoma multiforme treatment, and the mechanisms underlying the development of temozolomide resistance remain poorly understood. Enhanced DNA repair and mutagenesis can allow tumour cells to survive, contributing to resistance and tumour recurrence. Here, using recurrent temozolomide-refractory glioblastoma specimens, temozolomide-resistant cells, and resistant-xenograft models, we report that loss of miR-29c via c-Myc drives the acquisition of temozolomide resistance through enhancement of REV3L-mediated DNA repair and mutagenesis in glioblastoma. Importantly, disruption of c-Myc/miR-29c/REV3L signalling may have dual anticancer effects, sensitizing the resistant tumours to therapy as well as preventing the emergence of acquired temozolomide resistance. Our findings suggest a rationale for targeting the c-Myc/miR-29c/REV3L signalling pathway as a promising therapeutic approach for glioblastoma, even in recurrent, treatment-refractory settings.

  18. MicoRNA-451 is a novel tumor suppressor via targeting c-myc in head and neck squamous cell carcinomas

    Directory of Open Access Journals (Sweden)

    Huimin Wang

    2015-01-01

    Results: We showed that miRNA-451 was downregulated in paired HNSCC tissues as well as in cell lines. And overexpression of miRNA-451 in cells with low endogenous expression of miRNA-451 accelerated proliferation. To the contrast, knockdown of miRNA-451 in cells with high levels of miRNA-451 significantly reduced cell growth rate. Furthermore, we used bioinformatics and cellular methods to predict and prove that c-myc was targeted by miRNA-451, since forced expression of miRNA-451 leaded to decreased c-myc protein expression in HNSCC cells. Conclusion: Our findings identify miRNA-451 as a potential biomarker and suggest a key role of miRNA-451-c-myc pathway in HNSCC cell transformation, which could represent a novel therapeutic strategy in HNSCC treatment.

  19. Expression of K-ras, c-fos, and c-myc genes as a potential early indicator for late radiation damage of the kidney

    Energy Technology Data Exchange (ETDEWEB)

    Otsuka, Makoto [Kyushu Univ., Fukuoka (Japan). Dept. of Genetics Medical Inst. of Bioregulation

    1999-04-01

    We previously reported that an increased proliferation and the appearance of abnormally large nuclei in proximal tubule cells were observed in irradiated kidneys. A hypothetical model has been proposed in which the production of large nuclear cells results from abortive mitotic division and their loss is an eventual result of such an aberration. We measured the amount of K-ras, c-fos, and c-myc transcript taking the ratio of densities of bands for irradiated left kidney to unirradiated right kidney after RT-PCR procedure on 24 hours after 9, 12 and 15 Gy irradiation. As for c-myc, we found positive in 1 out of 10 after 9 Gy, 6 out of 10 after 12 Gy and 8 out of 10 after 15 Gy. Measuring the c-myc expression seems to be a potential very early indicator for late radiation damage of the kidney. (author)

  20. Chromosomal localization of the human gene encoding c-myc promoter-binding protein (MPB1) to chromosome 1p35-pter

    Energy Technology Data Exchange (ETDEWEB)

    White, R.A.; Dowler, L.L. [Univ. of Missouri, Kansas City, MO (United States); Adkison, L.R. [Mercer Univ. School of Medicine, Macon, GA (United States); Ray, R.B. [St. Louis Univ. Health Sciences Center, St. Louis, MO (United States)

    1997-02-01

    We report the mapping of the human gene MPB1 (c-myc promoter binding protein), a recently identified gene regulatory protein. MPB1 binds to the c-myc P2 promoter and exerts a negative regulatory role on c-myc transcription. Since exogenous expression from transfection of the MPB1 gene suppresses the tumorigenic property of breast cancer cells, there was interest in determining the chromosomal location of this gene. The human MPB1 gene was assigned to human chromosome 1p35-pter using Southern blot analyses of genomic DNAs from rodent-human somatic hybrid cell lines. A specific human genomic fragment was observed only in the somatic cell lines containing human chromosome 1 or the p35-pter region of the chromosome. 10 refs., 2 figs.

  1. Effect of the increased stability of the penicillin amidase mRNA on the protein expression levels.

    Science.gov (United States)

    Viegas, Sandra C; Schmidt, Dorothea; Kasche, Volker; Arraiano, Cecília M; Ignatova, Zoya

    2005-09-12

    Several factors at transcriptional, post-transcriptional or post-translational level determine the fate of a target protein and can severely restrict its yield. Here, we focus on the post-transcriptional regulation of the biosynthesis of the periplasmic protein, penicillin amidase (PA). The PA mRNA stability was determined under depleted RNase conditions in strains carrying single or multiple RNase deletions. Single deletion of the endonuclease RNase E yielded, as the highest, a fourfold stabilization of the PA mRNA. This effect, however, was reduced twice at post-translational level. The RNase II, generating secondary exonucleolytic cleavages in the mRNA, although not significantly influencing the PA mRNA decay, led also to an increase of the amount of mature PA. The non-proportional correlation between increased mRNA longevity and amount of active enzyme propose that the rational strategies for yield improvement must be based on a simultaneous tuning of more than one yield restricting factor.

  2. SALL4 as an Epithelial-Mesenchymal Transition and Drug Resistance Inducer through the Regulation of c-Myc in Endometrial Cancer.

    Directory of Open Access Journals (Sweden)

    Lei Liu

    Full Text Available SALL4 plays important roles in the development and progression of many cancers. However, the role and molecular mechanism of SALL4 in endometrial cancer remain elusive. In the present research, we have demonstrated that the expression of SALL4 was upregulated in endometrial cancer and correlated positively with tumor stage, metastases and poor survival of patients. The overexpression of SALL4 promoted the invasiveness in endometrial cancer cells, as indicated by the upregulation of mesenchymal cell marker N-cadherin and downregulation of the epithelial marker E-cadherin, and invasion assays in vitro. Additionally, there was also an increase in drug resistance in these cell models due to the upregulation of ATP-binding cassette multidrug transporter ABCB1 expression. Moreover, we also found that ABCB1 was critical for SALL4-induced drug resistance. In contrast, SALL4 knockdown restored drug sensitivity, reversed EMT, diminished cell metastasis and suppressed the downregulation of E-cadherin and the upregulation of N-cadherin and ABCB1. Furthermore, we showed that SALL4 upregulated c-Myc expression and c-Myc was a direct target for SALL4 by ChIP assay, depletion of c-Myc with siRNA abolished the SALL4-induced downregulation of E-cadherin, upregulation of N-cadherin and ABCB1, suggesting that c-Myc was a downstream target for SALL4 and required for SALL4-induced EMT, invasion and drugs resistance in endometrial cancer cells. These results indicated that SALL4 could induce EMT and resistance to antineoplastic drugs through the regulation of c-Myc. SALL4 and c-Myc may be novel therapeutic targets for endometrial cancer.

  3. The B-WICH chromatin-remodelling complex regulates RNA polymerase III transcription by promoting Max-dependent c-Myc binding

    Science.gov (United States)

    Sadeghifar, Fatemeh; Böhm, Stefanie; Vintermist, Anna; Östlund Farrants, Ann-Kristin

    2015-01-01

    The chromatin-remodelling complex B-WICH, comprised of William syndrome transcription factor, the ATPase SNF2h and nuclear myosin, specifically activates RNA polymerase III transcription of the 5S rRNA and 7SL genes. However, the underlying mechanism is unknown. Using high-resolution MN walking we demonstrate here that B-WICH changes the chromatin structure in the vicinity of the 5S rRNA and 7SL RNA genes during RNA polymerase III transcription. The action of B-WICH is required for the binding of the RNA polymerase machinery and the regulatory factors c-Myc at the 5S rRNA and 7SL RNA genes. In addition to the c-Myc binding site at the 5S genes, we have revealed a novel c-Myc and Max binding site in the intergenic spacer of the 5S rDNA. This region also contains a region remodelled by B-WICH. We demonstrate that c-Myc binds to both sites in a Max-dependent way, and thereby activate transcription by acetylating histone H3. The novel binding patterns of c-Myc and Max link transcription of 5S rRNA to the Myc/Max/Mxd network. Since B-WICH acts prior to c-Myc and other factors, we propose a model in which the B-WICH complex is required to maintain an open chromatin structure at these RNA polymerase III genes. This is a prerequisite for the binding of additional regulatory factors. PMID:25883140

  4. Investigating actinomycin D binding to G-quadruplex, i-motif and double-stranded DNA in 27-nt segment of c-MYC gene promoter.

    Science.gov (United States)

    Niknezhad, Zhila; Hassani, Leila; Norouzi, Davood

    2016-01-01

    c-MYC DNA is an attractive target for drug design, especially for cancer chemotherapy. Around 90% of c-MYC transcription is controlled by NHE III1, whose 27-nt purine-rich strand has the ability to form G-quadruplex structure. In this investigation, interaction of ActD with 27-nt G-rich strand (G/c-MYC) and its equimolar mixture with the complementary sequence, (GC/c-MYC) as well as related C-rich oligonucleotide (C/c-MYC) was evaluated. Molecular dynamic simulations showed that phenoxazine and lactone rings of ActD come close to the outer G-tetrad nucleotides indicating that ActD binds through end-stacking to the quadruplex DNA. RMSD and RMSF revealed that fluctuation of the quadruplex DNA increases upon interaction with the drug. The results of spectrophotometry and spectrofluorometry indicated that ActD most probably binds to the c-MYC quadruplex and duplex DNA via end-stacking and intercalation, respectively and polarity of ActD environment decreases due to the interaction. It was also found that binding of ActD to the GC-rich DNA is stronger than the two other forms of DNA. Circular dichroism results showed that the type of the three forms of DNA structures doesn't change, but their compactness alters due to their interaction with ActD. Finally, it can be concluded that ActD binds differently to double stranded DNA, quadruplex DNA and i-motif. Copyright © 2015 Elsevier B.V. All rights reserved.

  5. Resistance to arginine deiminase treatment in melanoma cells is associated with induced argininosuccinate synthetase expression involving c-Myc/HIF-1alpha/Sp4.

    Science.gov (United States)

    Tsai, Wen-Bin; Aiba, Isamu; Lee, Soo-yong; Feun, Lynn; Savaraj, Niramol; Kuo, Macus Tien

    2009-12-01

    Arginine deiminase (ADI)-based arginine depletion is a novel strategy under clinical trials for the treatment of malignant melanoma with promising results. The sensitivity of melanoma to ADI treatment is based on its auxotrophy for arginine due to a lack of argininosuccinate synthetase (AS) expression, the rate-limiting enzyme for the de novo biosynthesis of arginine. We show here that AS expression can be transcriptionally induced by ADI in melanoma cell lines A2058 and SK-MEL-2 but not in A375 cells, and this inducibility was correlated with resistance to ADI treatment. The proximal region of the AS promoter contains an E-box that is recognized by c-Myc and HIF-1alpha and a GC-box by Sp4. Through ChIP assays, we showed that under noninduced conditions, the E-box was bound by HIF-1alpha in all the three melanoma cell lines. Under arginine depletion conditions, HIF-1alpha was replaced by c-Myc in A2058 and SK-MEL-2 cells but not in A375 cells. Sp4 was constitutively bound to the GC-box regardless of arginine availability in all three cell lines. Overexpressing c-Myc by transfection upregulated AS expression in A2058 and SK-MEL-2 cells, whereas cotransfection with HIF-1alpha suppressed c-Myc-induced AS expression. These results suggest that regulation of AS expression involves interplay among positive transcriptional regulators c-Myc and Sp4, and negative regulator HIF-1alpha that confers resistance to ADI treatment in A2058 and SK-MEL-2 cells. Inability of AS induction in A375 cells under arginine depletion conditions was correlated by the failure of c-Myc to interact with the AS promoter.

  6. Expression of activated ATF-2, CREB and c-Myc in rat colon transversum after whole-body gamma-irradiation and its contribution to pathogenesis and biodosimetry.

    Science.gov (United States)

    Pejchal, Jaroslav; Osterreicher, Jan; Vilasová, Zdenka; Tichý, Ales; Vávrová, Jirina

    2008-04-01

    The purpose of our study is to examine phospho-ATF-2(Thr-69/71) (phospho-activating transcription factor-2, p-ATF-2), phospho-CREB(Ser-133) (phospho-cAMP response binding element protein, p-CREB), and phospho-c-Myc(Thr-58/Ser-62) (phosho-myelocytomatosis protooncogene, p-c-Myc) expression in irradiated rat colon transversum. Male Wistar rats were randomly divided to 28 groups and irradiated with whole-body gamma-radiation of 0, 0.25, 0.5, 0.75, 1, 2, 3, 4, 5, 6, 7, 8, 9, and 10 Gy. Samples were taken 4 and 24 hours after the irradiation, immunohistochemically stained. P-ATF-2, p-CREB, and p-c-Myc expression was measured. We measured increased cytoplasmatic p-ATF-2 expression 4 hours after irradiation by 0.25 - 1, 10 Gy and 24 hours after irradiation by 0.5 - 1, 10 Gy. Increased cytoplasmatic p-CREB expression was found 4 hours after irradiation by 0.25 - 1, 9, 10 Gy and 24 hours after irradiation by 0.25 - 1, 4, 10 Gy. Increased p-c-Myc cytoplasmatic expression was found 4 hours after irradiation by 0.25, 0.75, 4, 5 Gy and 24 hours after irradiation by 0.75, 1, 10 Gy. Nuclear p-ATF-2, p-CREB, and p-c-Myc expressions were similar to their cytoplasmatic expressions. The detection of p-ATF-2 and p-CREB might be considered as a perspective biodosimetric tool for irradiated enterocytes in vivo. The use of p-c-Myc appears to be controversial due to the ambivalent expression values.

  7. Differential effects of c-myc and ABCB1 silencing on reversing drug resistance in HepG2/Dox cells.

    Science.gov (United States)

    Yahya, Shaymaa M M; Hamed, Ahmed R; Emara, Mohamed; Soltan, Maha M; Abd-Ellatef, Gamal Eldein F; Abdelnasser, Salma M

    2016-05-01

    Multidrug resistance (MDR) in various kinds of cancers represents a true obstacle which hinders the successes of most of current available chemotherapies. ATP-binding cassette (ABC) trasporter proteins have been shown to contribute to the majority of MDR in various types of malignancies. c-myc has recently been reported to participate, at least partly, in MDR to some types of cancers. This study aimed to test whether c-myc could play a role, solely or with coordination with other ABCs, in the resistance of HepG2 cells to doxorubicin (Dox). MDR has been induced in wild-type HepG2 and has been verified both on gene and protein levels. Various assays including efflux assays as well as siRNA targeting ABCB1 and c-myc have been employed to explore the role of both candidate molecules in MDR in HepG2. Results obtained, with regard to ABCB1 silencing on HepG2/Dox cells, have shown that ABCB1-deficient cells exhibited a significant reduction in ABCC1 expression as compared to ABCB1-sufficient cells. However, these cells did not show a significant reduction in other tested ABCs (ABCC5 and ABCC10) while c-myc silencing had no significant effect on any of the studied ABCs. Moreover, silencing of ABCB1 on HepG2 significantly increased fluorescent calcein retention in HepG2 cells as compared to the control cells while downregulation of c-myc did not have any effect on fluorescent calcein retention. Altogether, this work clearly demonstrates that c-myc has no role in MDR of HepG2 to Dox which has been shown to be ABCB1-mediated in a mechanism which might involve ABCC1.

  8. Identification of functional networks of estrogen- and c-Myc-responsive genes and their relationship to response to tamoxifen therapy in breast cancer.

    Science.gov (United States)

    Musgrove, Elizabeth A; Sergio, C Marcelo; Loi, Sherene; Inman, Claire K; Anderson, Luke R; Alles, M Chehani; Pinese, Mark; Caldon, C Elizabeth; Schütte, Judith; Gardiner-Garden, Margaret; Ormandy, Christopher J; McArthur, Grant; Butt, Alison J; Sutherland, Robert L

    2008-08-20

    Estrogen is a pivotal regulator of cell proliferation in the normal breast and breast cancer. Endocrine therapies targeting the estrogen receptor are effective in breast cancer, but their success is limited by intrinsic and acquired resistance. With the goal of gaining mechanistic insights into estrogen action and endocrine resistance, we classified estrogen-regulated genes by function, and determined the relationship between functionally-related genesets and the response to tamoxifen in breast cancer patients. Estrogen-responsive genes were identified by transcript profiling of MCF-7 breast cancer cells. Pathway analysis based on functional annotation of these estrogen-regulated genes identified gene signatures with known or predicted roles in cell cycle control, cell growth (i.e. ribosome biogenesis and protein synthesis), cell death/survival signaling and transcriptional regulation. Since inducible expression of c-Myc in antiestrogen-arrested cells can recapitulate many of the effects of estrogen on molecular endpoints related to cell cycle progression, the estrogen-regulated genes that were also targets of c-Myc were identified using cells inducibly expressing c-Myc. Selected genes classified as estrogen and c-Myc targets displayed similar levels of regulation by estrogen and c-Myc and were not estrogen-regulated in the presence of siMyc. Genes regulated by c-Myc accounted for 50% of all acutely estrogen-regulated genes but comprised 85% (110/129 genes) in the cell growth signature. siRNA-mediated inhibition of c-Myc induction impaired estrogen regulation of ribosome biogenesis and protein synthesis, consistent with the prediction that estrogen regulates cell growth principally via c-Myc. The 'cell cycle', 'cell growth' and 'cell death' gene signatures each identified patients with an attenuated response in a cohort of 246 tamoxifen-treated patients. In multivariate analysis the cell death signature was predictive independent of the cell cycle and cell growth

  9. Identification of functional networks of estrogen- and c-Myc-responsive genes and their relationship to response to tamoxifen therapy in breast cancer.

    Directory of Open Access Journals (Sweden)

    Elizabeth A Musgrove

    Full Text Available BACKGROUND: Estrogen is a pivotal regulator of cell proliferation in the normal breast and breast cancer. Endocrine therapies targeting the estrogen receptor are effective in breast cancer, but their success is limited by intrinsic and acquired resistance. METHODOLOGY/PRINCIPAL FINDINGS: With the goal of gaining mechanistic insights into estrogen action and endocrine resistance, we classified estrogen-regulated genes by function, and determined the relationship between functionally-related genesets and the response to tamoxifen in breast cancer patients. Estrogen-responsive genes were identified by transcript profiling of MCF-7 breast cancer cells. Pathway analysis based on functional annotation of these estrogen-regulated genes identified gene signatures with known or predicted roles in cell cycle control, cell growth (i.e. ribosome biogenesis and protein synthesis, cell death/survival signaling and transcriptional regulation. Since inducible expression of c-Myc in antiestrogen-arrested cells can recapitulate many of the effects of estrogen on molecular endpoints related to cell cycle progression, the estrogen-regulated genes that were also targets of c-Myc were identified using cells inducibly expressing c-Myc. Selected genes classified as estrogen and c-Myc targets displayed similar levels of regulation by estrogen and c-Myc and were not estrogen-regulated in the presence of siMyc. Genes regulated by c-Myc accounted for 50% of all acutely estrogen-regulated genes but comprised 85% (110/129 genes in the cell growth signature. siRNA-mediated inhibition of c-Myc induction impaired estrogen regulation of ribosome biogenesis and protein synthesis, consistent with the prediction that estrogen regulates cell growth principally via c-Myc. The 'cell cycle', 'cell growth' and 'cell death' gene signatures each identified patients with an attenuated response in a cohort of 246 tamoxifen-treated patients. In multivariate analysis the cell death signature

  10. Long-term cultivation of in vitro Apis mellifera cells by gene transfer of human c-myc proto-oncogene.

    Science.gov (United States)

    Kitagishi, Yasuko; Okumura, Naoko; Yoshida, Hitomi; Nishimura, Yuri; Takahashi, Jun-ichi; Matsuda, Satoru

    2011-08-01

    Establishment of cell lines representative of honeybee character would greatly assist in their analysis. Here, we show that immortalized cell line, designated as MYN9, has been generated from honeybee embryo by the gene transfer of human c-myc proto-oncogene. The morphology of the cell is characteristic of embryonic stem cell, although the cell is stable and does not spontaneously differentiate. Polymerase chain reaction analyses show that the cell is originated from authentic honeybee cell. It is proposed that the integration of human c-myc gene into honeybee precursor populations results in the establishment of stable cell line suitable for cellular and molecular studies.

  11. Nucleolin and YB-1 are required for JNK-mediated interleukin-2 mRNA stabilization during T-cell activation

    DEFF Research Database (Denmark)

    Chen, C Y; Gherzi, R; Andersen, Jens S.

    2000-01-01

    Regulated mRNA turnover is a highly important process, but its mechanism is poorly understood. Using interleukin-2 (IL-2) mRNA as a model, we described a role for the JNK-signaling pathway in stabilization of IL-2 mRNA during T-cell activation, acting via a JNK response element (JRE) in the 5......' untranslated region (UTR). We have now identified two major RNA-binding proteins, nucleolin and YB-1, that specifically bind to the JRE. Binding of both proteins is required for IL-2 mRNA stabilization induced by T-cell activation signals and for JNK-induced stabilization in a cell-free system that duplicates...... essential features of regulated mRNA decay. Nucleolin and YB-1 are required for formation of an IL-2 mRNP complex that responds to specific mRNA stabilizing signals....

  12. PTB and TIAR binding to insulin mRNA 3′- and 5′UTRs; implications for insulin biosynthesis and messenger stability

    Directory of Open Access Journals (Sweden)

    Rikard G. Fred

    2016-09-01

    Conclusions: These experiments indicate that alterations in insulin mRNA stability and translation correlate with differential RBP binding. We propose that the balance between PTB on one hand and TIAR on the other participates in the control of insulin mRNA stability and utilization for insulin biosynthesis.

  13. The Csr system regulates genome-wide mRNA stability and transcription and thus gene expression in Escherichia coli.

    Science.gov (United States)

    Esquerré, Thomas; Bouvier, Marie; Turlan, Catherine; Carpousis, Agamemnon J; Girbal, Laurence; Cocaign-Bousquet, Muriel

    2016-04-26

    Bacterial adaptation requires large-scale regulation of gene expression. We have performed a genome-wide analysis of the Csr system, which regulates many important cellular functions. The Csr system is involved in post-transcriptional regulation, but a role in transcriptional regulation has also been suggested. Two proteins, an RNA-binding protein CsrA and an atypical signaling protein CsrD, participate in the Csr system. Genome-wide transcript stabilities and levels were compared in wildtype E. coli (MG1655) and isogenic mutant strains deficient in CsrA or CsrD activity demonstrating for the first time that CsrA and CsrD are global negative and positive regulators of transcription, respectively. The role of CsrA in transcription regulation may be indirect due to the 4.6-fold increase in csrD mRNA concentration in the CsrA deficient strain. Transcriptional action of CsrA and CsrD on a few genes was validated by transcriptional fusions. In addition to an effect on transcription, CsrA stabilizes thousands of mRNAs. This is the first demonstration that CsrA is a global positive regulator of mRNA stability. For one hundred genes, we predict that direct control of mRNA stability by CsrA might contribute to metabolic adaptation by regulating expression of genes involved in carbon metabolism and transport independently of transcriptional regulation.

  14. Nucleolus disassembly in mitosis and apoptosis: dynamic redistribution of phosphorylated-c-Myc, fibrillarin and Ki-67

    Directory of Open Access Journals (Sweden)

    C Soldani

    2009-06-01

    Full Text Available The nucleolus may undergo disassembly either reversibly during mitosis, or irreversibly in apoptosis, thus allowing the redistribution of the nucleolar proteins.We investigated here by immunocytochemistry the fate of three representative proteins, namely phosphorylated c-Myc, fibrillarin and Ki-67, and found that they behave independently in both processes: they relocate in distinct compartments during mitosis, whereas during apoptosis they may either be cleaved (Ki-67 or be extruded into the cytoplasm with a different kinetics and following an ordered, non chaotic program. The separation of these nucleolar proteins which occurs in early apoptotic nuclei continues also in the cytoplasm, and culminates in the final formation of apoptotic blebs containing different nucleolar proteins: this evidence confirms that the apoptotic bodies may be variable in size, content and surface reactivity, and include heterogeneous aggregates of nuclear proteins and/or nucleic acids.

  15. c-MYC-Induced Sebaceous Gland Differentiation Is Controlled by an Androgen Receptor/p53 Axis

    Directory of Open Access Journals (Sweden)

    Denny L. Cottle

    2013-02-01

    Full Text Available Although the sebaceous gland (SG plays an important role in skin function, the mechanisms regulating SG differentiation and carcinoma formation are poorly understood. We previously reported that c-MYC overexpression stimulates SG differentiation. We now demonstrate roles for the androgen receptor (AR and p53. MYC-induced SG differentiation was reduced in mice lacking a functional AR. High levels of MYC triggered a p53-dependent DNA damage response, leading to accumulation of proliferative SG progenitors and inhibition of AR signaling. Conversely, testosterone treatment or p53 deletion activated AR signaling and restored MYC-induced differentiation. Poorly differentiated human sebaceous carcinomas exhibited high p53 and low AR expression. Thus, the consequences of overactivating MYC in the SG depend on whether AR or p53 is activated, as they form a regulatory axis controlling proliferation and differentiation.

  16. Therapeutic potential of targeting IRES-dependent c-myc translation in multiple myeloma cells during ER stress.

    Science.gov (United States)

    Shi, Y; Yang, Y; Hoang, B; Bardeleben, C; Holmes, B; Gera, J; Lichtenstein, A

    2016-02-25

    Protein translation is inhibited by the unfolded protein response (UPR)-induced eIF-2α phosphorylation to protect against endoplasmic reticulum (ER) stress. In addition, we found additional inhibition of protein translation owing to diminished mTORC1 (mammalian target of rapamycin complex1) activity in ER-stressed multiple myeloma (MM) cells. However, c-myc protein levels and myc translation was maintained. To ascertain how c-myc was maintained, we studied myc IRES (internal ribosome entry site) function, which does not require mTORC1 activity. Myc IRES activity was upregulated in MM cells during ER stress induced by thapsigargin, tunicamycin or the myeloma therapeutic bortezomib. IRES activity was dependent on upstream MAPK (mitogen-activated protein kinase) and MNK1 (MAPK-interacting serine/threonine kinase 1) signaling. A screen identified hnRNP A1 (A1) and RPS25 as IRES-binding trans-acting factors required for ER stress-activated activity. A1 associated with RPS25 during ER stress and this was prevented by an MNK inhibitor. In a proof of principle, we identified a compound that prevented binding of A1 to the myc IRES and specifically inhibited myc IRES activity in MM cells. This compound, when used alone, was not cytotoxic nor did it inhibit myc translation or protein expression. However, when combined with ER stress inducers, especially bortezomib, a remarkable synergistic cytotoxicity ensued with associated inhibition of myc translation and expression. These results underscore the potential for targeting A1-mediated myc IRES activity in MM cells during ER stress.

  17. The RNA-binding protein HuR regulates DNA methylation through stabilization of DNMT3b mRNA.

    Science.gov (United States)

    López de Silanes, Isabel; Gorospe, Myriam; Taniguchi, Hiroaki; Abdelmohsen, Kotb; Srikantan, Subramanya; Alaminos, Miguel; Berdasco, María; Urdinguio, Rocío G; Fraga, Mario F; Jacinto, Filipe V; Esteller, Manel

    2009-05-01

    The molecular basis underlying the aberrant DNA-methylation patterns in human cancer is largely unknown. Altered DNA methyltransferase (DNMT) activity is believed to contribute, as DNMT expression levels increase during tumorigenesis. Here, we present evidence that the expression of DNMT3b is post-transcriptionally regulated by HuR, an RNA-binding protein that stabilizes and/or modulates the translation of target mRNAs. The presence of a putative HuR-recognition motif in the DNMT3b 3'UTR prompted studies to investigate if this transcript associated with HuR. The interaction between HuR and DNMT3b mRNA was studied by immunoprecipitation of endogenous HuR ribonucleoprotein complexes followed by RT-qPCR detection of DNMT3b mRNA, and by in vitro pulldown of biotinylated DNMT3b RNAs followed by western blotting detection of HuR. These studies revealed that binding of HuR stabilized the DNMT3b mRNA and increased DNMT3b expression. Unexpectedly, cisplatin treatment triggered the dissociation of the [HuR-DNMT3b mRNA] complex, in turn promoting DNMT3b mRNA decay, decreasing DNMT3b abundance, and lowering the methylation of repeated sequences and global DNA methylation. In summary, our data identify DNMT3b mRNA as a novel HuR target, present evidence that HuR affects DNMT3b expression levels post-transcriptionally, and reveal the functional consequences of the HuR-regulated DNMT3b upon DNA methylation patterns.

  18. In vivo study on the effects of microcystin extracts on the expression profiles of proto-oncogenes (c-fos, c-jun and c-myc) in liver, kidney and testis of male Wistar rats injected i.v. with toxins.

    Science.gov (United States)

    Li, Huiying; Xie, Ping; Li, Guangyu; Hao, Le; Xiong, Qian

    2009-01-01

    Microcystins (MCs) are a potent liver tumor promoter, possessing potent tumor-promoting activity and weak initiating activity. Proto-oncogenes are known to be involved in the tumor-promoting mechanisms of microcystin-LR. However, few data are available on the effects of MCs on proto-oncogenes in the whole animal. To investigate the effects of MCs on the expression profile of the proto-oncogenes in different organs, male Wistar rats were injected intravenously with microcystin extracts at a dose of 86.7 mug MC-LR eq/kg bw (MC-LR eq, MC-LR equivalents). mRNA levels of three proto-oncogenes c-fos, c-jun and c-myc in liver, kidney and testis were analyzed using quantitative real-time PCR at several time points post-injection. Significant induction of these genes at transcriptional level was observed in the three organs. In addition, the increase of mRNA expression of all three genes was much higher in liver than in kidney and testis. Meanwhile, the protein levels of c-Fos and c-Jun were investigated by western blotting. Both proteins were induced in the three organs. However, elevations of protein levels were much lower than those of mRNA levels. These findings suggest that the expression of c-fos, c-jun and c-myc might be one possible mechanism for the tumor-promoting activity and initiating activity of microcystins.

  19. AU-RICH ELEMENTS IN THE 3′-UTR REGULATE THE STABILITY OF THE 141 AMINO ACID ISOFORM OF PARATHYROID HORMONE-RELATED PROTEIN mRNA

    Science.gov (United States)

    Luchin, Alexander I.; Nadella, Murali V.P.; Thudi, Nanda K.; Dirksen, Wessel P.; Gulati, Parul; Fernandez, Soledad A.; Rosol, Thomas J.

    2012-01-01

    We demonstrated previously that parathyroid hormone-related protein (PTHrP) 1-141 mRNA is the least stable of three isoforms and is the only isoform that is stabilized by TGF-β. In order to understand how PTHrP mRNA is stabilized by TGF-β, we first sought to elucidate the mechanism(s) that are responsible for the instability of PTHrP isoform 1-141 mRNA. The 3′-UTR of isoform 1-141 contains four AU-rich elements (AREs), which are known to mediate mRNA degradation. We utilized a luciferase reporter system to test whether these four AREs are responsible for the short half-life of PTHrP 1-141 mRNA. Our results demonstrated that ARE elements in the 3′-UTR of PTHrP 1-141 mRNA play a significant role in regulation of the stability of the mRNA. It is known that AREs mediate their effects on mRNA stability through a number of ARE-binding proteins that recruit the exosome, a complex of exonucleases that degrades the mRNA. We identified tristetraproline (TTP) as an RNA-binding protein that may be involved in ARE-mediated degradation of PTHrP 1-141 mRNA. PMID:22960231

  20. AU-rich elements in the 3'-UTR regulate the stability of the 141 amino acid isoform of parathyroid hormone-related protein mRNA.

    Science.gov (United States)

    Luchin, Alexander I; Nadella, Murali V P; Thudi, Nanda K; Dirksen, Wessel P; Gulati, Parul; Fernandez, Soledad A; Rosol, Thomas J

    2012-11-25

    We demonstrated previously that parathyroid hormone-related protein (PTHrP) 1-141 mRNA is the least stable of three isoforms and is the only isoform that is stabilized by TGF-β. In order to understand how PTHrP mRNA is stabilized by TGF-β, we first sought to elucidate the mechanism(s) that are responsible for the instability of PTHrP isoform 1-141 mRNA. The 3'-UTR of isoform 1-141 contains four AU-rich elements (AREs), which are known to mediate mRNA degradation. We utilized a luciferase reporter system to test whether these four AREs are responsible for the short half-life of PTHrP 1-141 mRNA. Our results demonstrated that ARE elements in the 3'-UTR of PTHrP 1-141 mRNA play a significant role in regulation of the stability of the mRNA. It is known that AREs mediate their effects on mRNA stability through a number of ARE-binding proteins that recruit the exosome, a complex of exonucleases that degrades the mRNA. We identified tristetraproline (TTP) as an RNA-binding protein that may be involved in ARE-mediated degradation of PTHrP 1-141 mRNA. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

  1. c-Myc-Induced Survivin Is Essential for Promoting  the Notch-Dependent T Cell Differentiation from  Hematopoietic Stem Cells.

    Science.gov (United States)

    Haque, Rizwanul; Song, Jianyong; Haque, Mohammad; Lei, Fengyang; Sandhu, Praneet; Ni, Bing; Zheng, Songguo; Fang, Deyu; Yang, Jin-Ming; Song, Jianxun

    2017-03-06

    Notch is indispensable for T cell lineage commitment, and is needed for thymocyte differentiation at early phases. During early stages of T cell development, active Notch prevents other lineage potentials including B cell lineage and myeloid cell (e.g., dendritic cell) lineage. Nevertheless, the precise intracellular signaling pathways by which Notch promotes T cell differentiation remain unclear. Here we report that the transcription factor c-Myc is a key mediator of the Notch signaling-regulated T cell differentiation. In a well-established in vitro differentiation model of T lymphocytes from hematopoietic stem cells, we showed that Notch1 and 4 directly promoted c-Myc expression; dominant-negative (DN) c-Myc inhibited early T cell differentiation. Moreover, the c-Myc expression activated by Notch signaling increased the expression of survivin, an inhibitor of apoptosis (IAP) protein. We further demonstrated that over-expression of c-Myc increased the abundance of survivin and the T cell differentiation thereof, whereas dn c-Myc reduced survivin levels and concomitantly retarded the differentiation. The c-Myc-dependent survivin induction is functionally germane, because Notch-dependent T cell differentiation was canceled by the depletion of survivin. These results identify both c-Myc and survivin as important mediators of the Notch signaling-regulated differentiation of T lymphocytes from hematopoietic stem cells.

  2. Function of apoptosis and expression of the proteins Bcl-2, p53 and C-myc in the development of gastric cancer

    Institute of Scientific and Technical Information of China (English)

    An Gao Xu; Shao Guang Li; Ji Hong Liu; Ai Hua Gan

    2001-01-01

    @@INTRODUCTION In China ,the incidence and mortality of gastric cancer rank the second among all cancers. Recent development of cancer [1-20].The aim of this study was investigat the insight of apoptosis and bcl-2, p53 and C-myc protein expression in the development of gastric cancer .

  3. THE HEPARIN-BINDING DOMAIN AND V REGION OF FIBRONECTIN REGULATE APOPTOSIS BY SUPPRESSION OF P53 AND C-MYC IN HUMAN PRIMARY CELLS

    Science.gov (United States)

    In apoptosis the tumor suppressor p53 and oncogene c-myc, are usually upregulated. However, we report here an alternate pathway of regulation that is triggered by inflammatory-associated matrix fragments of fibronectin (FN) and leads to apoptosis. It is mediated by transcriptio...

  4. c-Myc regulates expression of NKG2D ligands ULBP1/2/3 in AML and modulates their susceptibility to NK-mediated lysis.

    Science.gov (United States)

    Nanbakhsh, Arash; Pochon, Cécile; Mallavialle, Aude; Amsellem, Sophie; Bourhis, Jean Henri; Chouaib, Salem

    2014-06-05

    Cytarabine (cytosine arabinoside) is one of the most effective drugs for the treatment of patients diagnosed with acute myeloid leukemia (AML). Despite its efficiency against AML cells, the emergence of drug resistance due to prolonged chemotherapy in most patients is still a major obstacle. Several studies have shown that drug resistance mechanisms alter the sensitivity of leukemia cells to immune system effector cells. To investigate this phenomenon, parental acute myeloid cell lines, HL-60 and KG-1, were continuously exposed to increasing doses of cytarabine in order to establish equivalent resistant cell lines, HL-60(R) and KG-1(R). Our data indicate that cytarabine-resistant cells are more susceptible to natural killer (NK)-mediated cell lysis as compared with parental cytarabine-sensitive cells. The increased susceptibility correlates with the induction of UL-16 binding proteins (ULBP) 1/2/3 and NK group 2, member D (NKG2D) ligands on target cells by a mechanism involving c-Myc induction. More importantly, chromatin immunoprecipitation assay revealed that ULBP1/3 are direct targets of c-Myc. Using drug-resistant primary AML blasts as target cells, inhibition of c-Myc resulted in decreased expression of NKG2D ligands and the subsequent impairment of NK cell lysis. This study provides for the first time, the c-Myc dependent regulation of NKG2D ligands in AML. © 2014 by The American Society of Hematology.

  5. The use of FISH-comet to detect c-Myc and TP 53 damage in extended-term lymphocyte cultures treated with terbuthylazine and carbofuran.

    Science.gov (United States)

    Mladinic, Marin; Zeljezic, Davor; Shaposhnikov, Sergey A; Collins, Andrew R

    2012-05-20

    Terbuthylazine and carbofuran are suspected to cause non-Hodgkin's lymphoma and lung cancer. We evaluated the effects of prolonged exposure to low concentrations on primary DNA damage by comet assay, and on the structural integrity of c-Myc and TP 53 genes by FISH-comet. Another novelty in studying these pesticides' genotoxicity is the use of 14-day extended-term human lymphocyte cultures. Concentrations corresponded to values of ADI and OEL: for terbuthylazine 0.58 ng/ml and 8 ng/ml; for carbofuran 8 ng/ml and 21.6 ng/ml, respectively. A possible effect of metabolic activation (S9) was also considered. Carbofuran treatment induced a significant migration of DNA into the tail in a concentration-dependent manner, while for terbuthylazine the effect was significant only at the higher concentration. Terbuthylazine caused migration of both c-Myc signals into the comet tail. A significant occurrence of TP 53 signals in the tail was observed at 8 ng/ml. Prolonged carbofuran treatment significantly elevated the migration of a single c-Myc signal into the tail in a concentration-dependent manner. With S9, distribution of signals shifted toward increased presence of both signals in tail. Our results showed impaired structural integrity of c-Myc and TP 53 due to prolonged exposure to terbuthylazine and carbofuran.

  6. Effect of Neem Leaf Extract (Azadirachta indica on c-MycOncogene Expression in 4T1 Breast Cancer Cells of BALB/c Mice

    Directory of Open Access Journals (Sweden)

    Chong Pei Pei

    2012-01-01

    Full Text Available Objective: Breast cancer is the most common cause of cancer-related deaths in women both worldwide and in Malaysia. Azadirachta indica (A. Juss, commonly known as neem, is one of the most versatile medicinal plants that has gained worldwide prominence due to its medicinal properties. However, the anticancer effect of ethanolic neem leaf extract against breast cancer has not been documented. The purpose of the present study is to investigate the effect of neem leaf extract on c-Myc oncogene expression in 4T1 breast cancer BALB/c mice.Materials and Methods: In this experimental study, A total of 48 female BALB/c mice were divided randomly into four groups of 12 mice per group: i.cancer control (CC treated with 0.5% Tween 20 in PBS, ii. 0.5 μg/mL tamoxifen citrate (CT, iii. 250 mg/kg neem leaf extract (C250, and iv. 500 mg/kg neem leaf extract (C500. In situ reverse transcription polymerase chain reaction (in situ RT-PCR was applied to evaluate suppression of c-Myc oncogene expression in breast cancer tissue.Results: The C500 group showed significant (p<0.05 suppression of c-Myc oncogene expression compared to the CC group.Conclusion: c-Myc was found to be down regulated under the effect of 500 mg/kg ethanolicneem leaf extract.

  7. Simultaneous detection of human papillomavirus integration and c-MYC gene amplification in cervical lesions: an emerging marker for the risk to progression.

    Science.gov (United States)

    Gimenes, Fabrícia; Souza, Raquel Pantarotto; de Abreu, André Luelsdorf Pimenta; Pereira, Monalisa Wolski; Consolaro, Marcia Edilaine Lopes; da Silva, Vânia Ramos Sela

    2016-04-01

    The persistence of high-risk oncogenic human papillomavirus (HR-HPV) infection and its integration into the host genome are key steps in the induction of malignant alterations. c-MYC chromosome region is a frequent localization for HPV insertion that has been observed in chromosome band 8q24 by fluorescence in situ hybridization (FISH). We report the HPV viral integration and amplification patterns of the c-MYC gene in cytological smears with FISH as a potential biomarker for the progression of squamous intraepithelial lesions (SIL). HPV detection and genotyping by polymerase chain reaction (PCR) and FISH analysis by "Vysis Cervical FISH Probe" kit (ABBOTT Molecular Inc.) were performed in 37 cervical samples including 8 NILM, 7 ASC-US, 7 LSIL, 3 ASC-H, 7 HSIL and 5 SCC. The results show concordance between FISH and PCR techniques for HPV detection. The majority of the samples contained HR-HPV, the majority being -16 and -18 genotypes. HPV integration as determined by FISH was most frequent in high-risk lesions. The c-MYC gene amplification was found only in HPV-positive samples and was detected primarily in high-risk lesions and in cells with an integrated form of HPV. HPV integration and c-MYC gene amplification detected by FISH could be an important biomarker for use in clinical practice to determine SIL with a risk of progression.

  8. Gains and amplifications of c-myc, EGFR, and 20.q13 loci in the no dysplasia-dysplasia-adenocarcinoma sequence of Barrett's esophagus

    NARCIS (Netherlands)

    Rygiel, Agnieszka M.; Milano, Francesca; ten Kate, Fibo J.; Schaap, Annet; Wang, Kenneth K.; Peppelenbosch, Mackel P.; Bergman, Jacques J. G. H. M.; Krishnadath, Kausillia K.

    2008-01-01

    The progression of Barrett's esophagus to esophageal adenocarcinoma is often characterized by the accumulation of genetic abnormalities. The goal was to evaluate the copy number alterations of several oncogene loci, including 7p12 [epidermal growth factor receptor (EGFR)], 8q24 (c-myc), and 20q13 in

  9. Effects of matrine on the growth inhibition, c-myc and hTERT protein expression in human adenocarcinoma lung cancer cell line A549

    Directory of Open Access Journals (Sweden)

    Qiong CHEN

    2008-08-01

    Full Text Available Background and objective It was reported that telomerase was associated with the oncogenesis and progression of cancer, and to be the common targets of cancer therapy. The mechanism of matrine on lung cancer in vitro is not clear. We studied the effect of matrine on growth of human lung adenocarcinoma A549 cells and the mechanism related with telomerase. Methods MTT was used for measuring A549 cells viability, Hoechst 33342-propidium iodide fluorescent staining for observing apoptotic cells, flow cytometry (FCM for analyzing cell cycle and apoptosis, and immunocytochemistry for measuring the protein expressions of c-myc and hTERT in A549 cells. Results Matrine inhibited the proliferation of A549 cells with a time-dose-dependent manner (P<0.05. Hoechst 33342-propidium iodide staining showed apoptotic cells with chromatin condensation and fragmentation of nuclei. FCM analysis indicated elevating rate of cells in G0/G1 phase, lowering rate of that in S phase and the highering apoptotic rate. The levels of c-myc and hTERT protein expression in the matrine group was lower than that in the control group (P<0.05, and AOD of c-myc showed positive correlation with AOD of hTERT (r=0.633, P<0.01 Conclusion The inhibitory effect of matrine on A549 cells may be related to the lower expression of c-myc and hTERT.

  10. Sodium arsenite alters cell cycle and MTHFR, MT1/2, and c-Myc protein levels in MCF-7 cells.

    Science.gov (United States)

    Ruiz-Ramos, Ruben; López-Carrillo, Lizbeth; Albores, Arnulfo; Hernández-Ramírez, Raúl U; Cebrian, Mariano E

    2009-12-15

    There is limited available information on the effects of arsenic on enzymes participating in the folate cycle. Therefore, our aim was to evaluate the effects of sodium arsenite on the protein levels of methylenetetrahydrofolate reductase (MTHFR) and dihydrofolate reductase (DHFR) and its further relationship with the expression MT1/2 and c-myc in MCF-7 cells. Arsenite treatment (0-10 microM) for 4 h decreased MTHFR levels in a concentration-dependent fashion without significant effects on DHFR. The effects on MTHFR were observed at arsenite concentrations not significantly affecting cell viability. We also observed an increase in S-phase recruitment at all concentrations probed. Lower concentrations ( or =5 microM) or longer treatment periods induced apoptosis. Arsenite also induced dose-dependent increases in MT1/2 and c-Myc protein levels. The levels of MTHFR were inversely correlated to MT1/2 and c-Myc overexpression and increased S-phase recruitment. Our findings indicate that breast epithelial cells are responsive to arsenite and suggest that exposure may pose a risk for breast cancer. The reductions in MTHFR protein levels contribute to understand the mechanisms underlying the induction of genes influencing growth regulation, such as c-myc and MT1/2. However, further research is needed to ascertain if the effects here reported following short-time and high-dose exposure are relevant for human populations chronically exposed to low arsenic concentrations.

  11. HeLa和SiHa细胞中Skp2、p27和C-myc的表达%Expressions of Skp2、p27 and C-myc in HeLa and SiHa Cells

    Institute of Scientific and Technical Information of China (English)

    薛翔; 公丕军; 范引侠

    2012-01-01

    Objective: To test the expressions of S-phase kinase-associated protein 2 (Skp2), C-myc and p27 in HeLa and SiHa cells from the levels of RNA and protein and to investgate the meaning of those indexes in cervical cancerous cells. Methods:We tested the expressions of Skp2, p27 and C-myc in HeLa and SiHa cell lines by immunohistochemistry, western blotting as well as semiquantitative PCR . Results: Immunohistochemistry results showed that the expressions of Skp2 and C-myc were obviously stronger in HeLa cells than those in SiHa cells (P =0.032 and P = 0.026). While the expression of p27 was weaker in HeLa cells than that in SiHa cells (P=0.035). Western blot results showed that the expressions of endogenous Skp2 and C-myc protein in HeLa cells were as 2.8 and 1.5 times of SiHa cells respectively. However, the expression of p27 protein in SiHa cells was as 2.7 times of those in HeLa cells. RT-PCR results showed that the expression levels of endogenous Skp2 and C-myc mRNA in HeLa cells were higher than those in Si-Hha cells(P = 0.034 and P = 0.028, respectively), meanwhile, the expression of p27mRNA in SiHa cells was higher than that of HeLa cells (P=0.002). Conclusions: The expressions of Skp2 and C-myc in HeLa cells are obviously higher than those in SiHa cells. The expression of p27 in HeLa cells is lower than that in SiHa cells.%目的:检测S期激酶相关蛋白2( Skp2)、C-myc、p27在宫颈癌HeLa及SiHa细胞系中的表达,明确这些指标在宫颈癌细胞系表达的意义.方法:通过细胞免疫组化、Western blot、RT-PCR技术分析Skp2、p27和C-myc在蛋白和mRNA水平表达的差异.结果:免疫组化显示:HeLa细胞中Skp2和C-myc表达强度高于SiHa细胞(P=0.032和P=0.026),而HeLa细胞中p27蛋白表达弱于SiHa细胞(P=0.035).Western blot显示:在HeLa细胞中Skp2和C-myc蛋白表达分别是SiHa细胞表达量的2.8倍和1.5倍;而SiHa细胞中的p27蛋白的表达水平是He-La细胞中表达的2.7倍.RT-PCR结果

  12. The inhibition effects of the c-myc targeting CRISPR/Cas9 adenovirus system on hepatoma cells%靶向 c-myc 基因的 CRISPR/Cas9腺病毒系统对肝癌的抑制作用

    Institute of Scientific and Technical Information of China (English)

    连竹生; 梁鑫; 金桂花; 吴领知; 韩苏夏

    2016-01-01

    目的:设计、构建并包装靶向 c-myc 基因的 CRISPR/Cas9腺病毒;评估靶向 c-myc 基因的 CRISPR/Cas9腺病毒系统对肝癌的抑制作用。方法:采用生物信息学网站设计靶向 c-myc 基因的 gRNA,以 GFP 作为对照设计GFP gRNA;通过 T7E1筛选出编辑效率高的 gRNA 并将筛选的 gRNA 构建 CRISPR/Cas9腺病毒载体并包装腺病毒,通过分析细胞增殖、周期和凋亡及迁移能力的变化来评估靶向 c-myc 基因的 CRISPR/Cas9腺病毒系统对肝癌的抑制作用。结果:成功设计、构建并包装靶向 c-myc 基因的 CRISPR/Cas9腺病毒;靶向 c-myc 基因的 CRISPR/Cas9腺病毒系统能够显著抑制 Hepa1-6细胞的增殖和迁移、阻滞细胞周期进程,但对细胞凋亡无影响。结论:靶向 c-myc 基因的 CRISPR/Cas9腺病毒系统可在细胞水平明显抑制肝癌细胞的生长。%Aim:To design,construct and package the CRISPR/Cas9 adenovirus system for targeting the mouse c-myc gene;To evaluate the inhibition efficiency of the constructed adenovirus system on c-myc gene in hepatoma cells.Methods:We designed gRNAs for targeting the mouse c-myc gcontrolene and used another gene (gRNAs for GFP)as control based on bioinformatics website.The editing efficiencies of these gRNAs were determined by T7E1 cleavage.The gRNAs with higher editing efficiency were se-lected and packed into adenovirus for the following experiments.Firstly,Hepa 1-6 cells were infected with the constructed adenovirus,then cell proliferation,cell cycle,cell apoptosis and migration assays were detected to de the inhibition efficiency of the adenovirus on hepatoma cells.Statistical analyses were performed with SPSS(version 18.0)and t-test,P <0.05 was considered statistically significant.Re-sults:The CRISPR/Cas9 adenovirus system targeting the mouse c-myc gene was successfully designed constructed and packaged.Compared with the control group,the experiment groups (with CRISPR/Cas9

  13. The tRNA methyltransferase NSun2 stabilizes p16INK4 mRNA by methylating the 3′-untranslated region of p16

    OpenAIRE

    Zhang, Xiaotian; Liu, Zhenyun; Yi, Jie; Tang, Hao; Xing, Junyue; Yu, Minqwei; Tong, Tanjun; Shang, Yongfeng; Gorospe, Myriam; Wang, Wengong

    2012-01-01

    The impact of methylation of the 3′-untranslated region (UTR) of a messenger RNA (mRNA) remains largely unknown. Here we show that NSun2, a transfer RNA methyltransferase, inhibits the turnover of p16INK4 mRNA. Knockdown of NSun2 reduces p16 expression by shortening the half-life of the p16 mRNA, while overexpression of NSun2 stabilizes the p16 mRNA. In vitro methylation assays show that NSun2 methylates the p16 3′UTR at A988. Knockdown of NSun2 reduces the stability of the EGFP-p16 chimeric ...

  14. PGE2-driven expression of c-Myc and oncomiR-17-92 contributes to apoptosis resistance in NSCLC.

    Science.gov (United States)

    Krysan, Kostyantyn; Kusko, Rebecca; Grogan, Tristan; O'Hearn, James; Reckamp, Karen L; Walser, Tonya C; Garon, Edward B; Lenburg, Marc E; Sharma, Sherven; Spira, Avrum E; Elashoff, David; Dubinett, Steven M

    2014-05-01

    Aberrant expression of microRNAs (miRNA) with oncogenic capacities (oncomiRs) has been described for several different malignancies. The first identified oncomiR, miR-17-92, is frequently overexpressed in a variety of cancers and its targets include the tumor suppressor PTEN. The transcription factor c-Myc (MYC) plays a central role in proliferative control and is rapidly upregulated upon mitogenic stimulation. Expression of c-Myc is frequently deregulated in tumors, facilitating proliferation and inhibiting terminal differentiation. The c-Myc-regulated network comprises a large number of transcripts, including those encoding miRNAs. Here, prostaglandin E2 (PGE2) exposure rapidly upregulates the expression of the MYC gene followed by the elevation of miR-17-92 levels, which in turn suppresses PTEN expression, thus enhancing apoptosis resistance in non-small cell lung cancer (NSCLC) cells. Knockdown of MYC expression or the miR-17-92 cluster effectively reverses this outcome. Similarly, miR-17-92 levels are significantly elevated in NSCLC cells ectopically expressing COX-2. Importantly, circulating miR-17-92 was elevated in the blood of patients with lung cancer as compared with subjects at risk for developing lung cancer. Furthermore, in patients treated with celecoxib, miR-17-92 levels were significantly reduced. These data demonstrate that PGE2, abundantly produced by NSCLC and inflammatory cells in the tumor microenvironment, is able to stimulate cell proliferation and promote resistance to pharmacologically induced apoptosis in a c-Myc and miR-17-92-dependent manner. This study describes a novel mechanism, involving c-Myc and miR-17-92, which integrates cell proliferation and apoptosis resistance. ©2014 AACR.

  15. c-MYC Generates Repair Errors via Increased Transcription of Alternative-NHEJ Factors, LIG3 and PARP1, in Tyrosine Kinase-Activated Leukemias.

    Science.gov (United States)

    Muvarak, Nidal; Kelley, Shannon; Robert, Carine; Baer, Maria R; Perrotti, Danilo; Gambacorti-Passerini, Carlo; Civin, Curt; Scheibner, Kara; Rassool, Feyruz V

    2015-04-01

    Leukemias expressing the constitutively activated tyrosine kinases (TK) BCR-ABL1 and FLT3/ITD activate signaling pathways that increase genomic instability through generation of reactive oxygen species (ROS), DNA double-strand breaks (DSB), and error-prone repair. The nonhomologous end-joining (NHEJ) pathway is a major pathway for DSB repair and is highly aberrant in TK-activated leukemias; an alternative form of NHEJ (ALT-NHEJ) predominates, evidenced by increased expression of DNA ligase IIIα (LIG3) and PARP1, increased frequency of large genomic deletions, and repair using DNA sequence microhomologies. This study, for the first time, demonstrates that the TK target c-MYC plays a role in transcriptional activation and subsequent expression of LIG3 and PARP1 and contributes to the increased error-prone repair observed in TK-activated leukemias. c-MYC negatively regulates microRNAs miR-150 and miR-22, which demonstrate an inverse correlation with LIG3 and PARP1 expression in primary and cultured leukemia cells and chronic myelogenous leukemia human patient samples. Notably, inhibition of c-MYC and overexpression of miR-150 and -22 decreases ALT-NHEJ activity. Thus, BCR-ABL1 or FLT3/ITD induces c-MYC expression, leading to genomic instability via augmented expression of ALT-NHEJ repair factors that generate repair errors. In the context of TK-activated leukemias, c-MYC contributes to aberrant DNA repair through downstream targets LIG3 and PARP1, which represent viable and attractive therapeutic targets. ©2015 American Association for Cancer Research.

  16. Triptolide inhibits COX-2 expression by regulating mRNA stability in TNF-{alpha}-treated A549 cells

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Lixin; Zhang, Shuang; Jiang, Zhenzhou; Huang, Xin; Wang, Tao; Huang, Xiao; Li, Han [Jiangsu Center for Drug Screening, China Pharmaceutical University, Nanjing 210009 (China); Zhang, Luyong, E-mail: lyzhang@cpu.edu.cn [Jiangsu Center for Drug Screening, China Pharmaceutical University, Nanjing 210009 (China)

    2011-12-09

    Highlights: Black-Right-Pointing-Pointer Triptolide inhibited COX-2 expression and the half-life of COX-2 mRNA is decreased. Black-Right-Pointing-Pointer The HuR protein shuttling from nucleus to cytoplasm is inhibited by triptolide. Black-Right-Pointing-Pointer Triptolide inhibited 3 Prime -UTR fluorescence reporter gene activity. Black-Right-Pointing-Pointer COX-2 mRNA binding to HuR is decreased by triptolide in pull-down experiments. -- Abstract: Cyclooxygenase-2 (COX-2) over-expression is frequently associated with human non-small-cell lung cancer (NSCLC) and involved in tumor proliferation, invasion, angiogenesis and resistance to apoptosis. In the present study, the effects of triptolide on COX-2 expression in A549 cells were investigated and triptolide was found to inhibit TNF-{alpha}-induced COX-2 expression. In our further studies, it was found that triptolide decreased the half-life of COX-2 mRNA dramatically and that it inhibited 3 Prime -untranslated region (3 Prime -UTR) fluorescence reporter gene activity. Meanwhile, triptolide inhibited the HuR shuttling from nucleus to cytoplasm. After triptolide treatment, decreased COX-2 mRNA in pull-down experiments with anti-HuR antibodies was observed, indicating that the decreased cytoplasmic HuR is responsible for the decreased COX-2 mRNA. Taken together, our results provided evidence for the first time that triptolide inhibited COX-2 expression by COX-2 mRNA stability modulation and post-transcriptional regulation. These results provide a novel mechanism of action for triptolide which may be important in the treatment of lung cancer.

  17. Posttranscriptional regulation of GAP-43 gene expression in PC12 cells through protein kinase C-dependent stabilization of the mRNA.

    Science.gov (United States)

    Perrone-Bizzozero, N I; Cansino, V V; Kohn, D T

    1993-03-01

    We have previously shown that nerve growth factor (NGF) selectively stabilizes the GAP-43 mRNA in PC12 cells. To study the cellular mechanisms for this post-transcriptional control and to determine the contribution of mRNA stability to GAP-43 gene expression, we examined the effects of several agents that affect PC12 cell differentiation on the level of induction and rate of degradation of the GAP-43 mRNA. The NGF-mediated increase in GAP-43 mRNA levels and neurite outgrowth was mimicked by the phorbol ester TPA, but not by dibutyryl cAMP or the calcium ionophore A12783. Downregulation of protein kinase C (PKC) by high doses of phorbol esters or selective PKC inhibitors prevented the induction of this mRNA by NGF, suggesting that NGF and TPA act through a common PKC-dependent pathway. In mRNA decay studies, phorbol esters caused a selective 6-fold increase in the half-life of the GAP-43 mRNA, which accounts for most of the induction of this mRNA by TPA. The phorbol ester-induced stabilization of GAP-43 mRNA was blocked by the protein kinase inhibitor polymyxin B and was partially inhibited by dexamethasone, an agent that blocks GAP-43 expression and neuronal differentiation in PC12 cells. In contrast, the rates of degradation and the levels of the GAP-43 mRNA in control and TPA-treated cells were not affected by cycloheximide treatment. Thus, changes in GAP-43 mRNA turnover do not appear to require continuous protein synthesis. In conclusion, these data suggest that PKC activity regulates the levels of the GAP-43 mRNA in PC12 cells through a novel, translation-independent mRNA stabilization mechanism.

  18. The manganese superoxide dismutase Ala16Val dimorphism modulates both mitochondrial import and mRNA stability.

    Science.gov (United States)

    Sutton, Angela; Imbert, Audrey; Igoudjil, Anissa; Descatoire, Véronique; Cazanave, Sophie; Pessayre, Dominique; Degoul, Françoise

    2005-05-01

    A genetic dimorphism incorporates either alanine (Ala) or valine (Val) in the mitochondrial targeting sequence (MTS) of manganese superoxide dismutase (MnSOD). The Ala-MTS confers a 40% higher MnSOD activity than the Val-MTS after import into isolated mitochondria in vitro. The present study aimed to characterize functional consequences in whole cells. HuH7 human hepatoma cells were transfected with vectors encoding for the human Ala- or Val-MnSOD variants fused to a Myc-His-tag. The Ala-variant resulted in four-fold higher levels of the mature exogenous protein and MnSOD activity than the Val-variant. Studies with a proteasome inhibitor indicated that precursor proteins are either imported into the mitochondria or degraded by the proteasome. Despite identical levels 8 h after transfection, mRNA levels at 36 h were two-fold higher for the Ala-encoding mRNA than the Val-mRNA. Decreasing the mitochondrial membrane potential decreased both MnSOD mitochondrial import and its mRNA levels. Much larger differences in the activity of the human Val- and Ala-MnSOD variants are observed in whole cells rather than after import experiments performed in vitro. First, the slowly imported Val-MnSOD is degraded by the proteasome in cells. Second, the slower mitochondrial import of the Val-variant may be associated with decreased mRNA stability, possibly due to impaired cotranslational import.

  19. Post-transcriptional Stabilization of Ucp1 mRNA Protects Mice from Diet-Induced Obesity

    Directory of Open Access Journals (Sweden)

    Akinori Takahashi

    2015-12-01

    Full Text Available Uncoupling protein 1 (Ucp1 contributes to thermogenesis, and its expression is regulated at the transcriptional level. Here, we show that Ucp1 expression is also regulated post-transcriptionally. In inguinal white adipose tissue (iWAT of mice fed a high-fat diet (HFD, Ucp1 level decreases concomitantly with increases in Cnot7 and its interacting partner Tob. HFD-fed mice lacking Cnot7 and Tob express elevated levels of Ucp1 mRNA in iWAT and are resistant to diet-induced obesity. Ucp1 mRNA has an elongated poly(A tail and persists in iWAT of Cnot7−/− and/or Tob−/− mice on a HFD. Ucp1 3′-UTR-containing mRNA is more stable in cells expressing mutant Tob that is unable to bind Cnot7 than in WT Tob-expressing cells. Tob interacts with BRF1, which binds to an AU-rich element in the Ucp1 3′-UTR. BRF1 knockdown partially restores the stability of Ucp1 3′-UTR-containing mRNA. Thus, the Cnot7-Tob-BRF1 axis inhibits Ucp1 expression and contributes to obesity.

  20. The circadian deadenylase Nocturnin is necessary for stabilization of the iNOS mRNA in mice.

    Directory of Open Access Journals (Sweden)

    Shuang Niu

    Full Text Available Nocturnin is a member of the CCR4 deadenylase family, and its expression is under circadian control with peak levels at night. Because it can remove poly(A tails from mRNAs, it is presumed to play a role in post-transcriptional control of circadian gene expression, but its target mRNAs are not known. Here we demonstrate that Nocturnin expression is acutely induced by the endotoxin lipopolysaccharide (LPS. Mouse embryo fibroblasts (MEFs lacking Nocturnin exhibit normal patterns of acute induction of TNFα and iNOS mRNAs during the first three hours following LPS treatment, but by 24 hours, while TNFα mRNA levels are indistinguishable from WT cells, iNOS message is significantly reduced 20-fold. Accordingly, analysis of the stability of the mRNAs showed that loss of Nocturnin causes a significant decrease in the half-life of the iNOS mRNA (t(1/2 = 3.3 hours in Nocturnin knockout MEFs vs. 12.4 hours in wild type MEFs, while having no effect on the TNFα message. Furthermore, mice lacking Nocturnin lose the normal nighttime peak of hepatic iNOS mRNA, and have improved survival following LPS injection. These data suggest that Nocturnin has a novel stabilizing activity that plays an important role in the circadian response to inflammatory signals.

  1. Relationship of Amplification and Expression of the C-MYC Gene with Survival among Gastric Cancer Patients.

    Science.gov (United States)

    Khaleghian, Malihea; Shakoori, Abbas; Razavi, Amirnader Emami; Azimi, Cyrus

    2015-01-01

    During the past decades, the incidence and mortality rate of stomach cancer has demonstrated a great decrease in the world, but it is still one of the most common and fatal cancers especially among men worldwide, including Iran. The MYC proto-oncogene, which is located at 8q24.1, regulates 15% of genes and is activated in 20% of all human tumors. MYC amplification and overexpression of its protein product has been reported in 15-30% of gastric neoplasias. The aim of this investigation was to find the relative efficacy of CISH (chromogenic in situ hybridization) or IHC (immunohistochemistry) in diagnosis and prognosis of gastric cancer, as well as the relationship of amplification and expression of C-MYC gene with patient survival. In this cross-sectional study, 102 samples of gastric cancer were collected from patients who had undergone primary surgical resection at the Cancer Institute Hospital, Tehran University of Medical Sciences, from July 2009 to March 2014. All samples were randomly selected from those who were diagnosed with gastric adenocarcinomas. CISH and IHC methods were performed on all of them. Patients were classified into two groups. The first consisted of stage I and II cases, and the second of stage III and IV. Survival tests for both groups was carried out with referrnce to CISH test reults. Group II (stage III and IV) with CISH+ featured lower survival than those with CISH- (p=0.233), but group I (stage I and II) patients demonstrated no significant variation with CISH+ or CISH- (p=0.630). Kaplan-Meier for both groups was carried out with IHC test findings and showed similar results. This data revealed that both diffuse and intestinal types of gastric cancer occurred significantly more in men than women. Our data also showed that CISH+ patients (43%) were more frequent in comparison with IHC+ patients (14.7%). For planning treatment of gastric cancer patients, by focusing on expanding tumors, which is the greatest concern of the surgeons and

  2. c-Myc quadruplex-forming sequence Pu-27 induces extensive damage in both telomeric and nontelomeric regions of DNA.

    Science.gov (United States)

    Islam, Md Ashraful; Thomas, Shelia D; Murty, Vundavalli V; Sedoris, Kara J; Miller, Donald M

    2014-03-21

    Quadruplex-forming DNA sequences are present throughout the eukaryotic genome, including in telomeric DNA. We have shown that the c-Myc promoter quadruplex-forming sequence Pu-27 selectively kills transformed cells (Sedoris, K. C., Thomas, S. D., Clarkson, C. R., Muench, D., Islam, A., Singh, R., and Miller, D. M. (2012) Genomic c-Myc quadruplex DNA selectively kills leukemia. Mol. Cancer Ther. 11, 66-76). In this study, we show that Pu-27 induces profound DNA damage, resulting in striking chromosomal abnormalities in the form of chromatid or chromosomal breaks, radial formation, and telomeric DNA loss, which induces γ-H2AX in U937 cells. Pu-27 down-regulates telomeric shelterin proteins, DNA damage response mediators (RAD17 and RAD50), double-stranded break repair molecule 53BP1, G2 checkpoint regulators (CHK1 and CHK2), and anti-apoptosis gene survivin. Interestingly, there are no changes of DNA repair molecules H2AX, BRCA1, and the telomere maintenance gene, hTERT. ΔB-U937, where U937 cells stably transfected with deleted basic domain of TRF2 is partially sensitive to Pu-27 but exhibits no changes in expression of shelterin proteins. However, there is an up-regulation of CHK1, CHK2, H2AX, BRCA1, and survivin. Telomere dysfunction-induced foci assay revealed co-association of TRF1with γ-H2AX in ATM deficient cells, which are differentially sensitive to Pu-27 than ATM proficient cells. Alt (alternating lengthening of telomere) cells are relatively resistant to Pu-27, but there are no significant changes of telomerase activity in both Alt and non-Alt cells. Lastly, we show that this Pu-27-mediated sensitivity is p53-independent. The data therefore support two conclusions. First, Pu-27 induces DNA damage within both telomeric and nontelomeric regions of the genome. Second, Pu-27-mediated telomeric damage is due, at least in part, to compromise of the telomeric shelterin protein complex.

  3. The p53 target Wig-1 regulates p53 mRNA stability through an AU-rich element

    DEFF Research Database (Denmark)

    Vilborg, Anna; Glahder, Jacob-Andreas Harald; Wilhelm, Margareta T

    2009-01-01

    The p53 target gene Wig-1 encodes a double-stranded-RNA-binding zinc finger protein. We show here that Wig-1 binds to p53 mRNA and stabilizes it through an AU-rich element (ARE) in the 3' UTR of the p53 mRNA. This effect is mirrored by enhanced p53 protein levels in both unstressed cells and cells...... exposed to p53-activating stress agents. Thus, the p53 target Wig-1 is a previously undescribed ARE-regulating protein that acts as a positive feedback regulator of p53, with implications both for the steady-state levels of p53 and for the p53 stress response. Our data reveal a previously undescribed link...

  4. Secondary structures involving the poly(A tail and other 3’ sequences are major determinants of mRNA isoform stability in yeast

    Directory of Open Access Journals (Sweden)

    Zarmik Moqtaderi

    2014-04-01

    Full Text Available In Saccharomyces cerevisiae, previous measurements of mRNA stabilities have been determined on a per-gene basis. We and others have recently shown that yeast genes give rise to a highly heterogeneous population of mRNAs due to extensive alternative 3’ end formation. Typical genes can have fifty or more distinct mRNA isoforms with 3’ endpoints differing by as little as one and as many as hundreds of nucleotides. In our recent paper [Geisberg et al. Cell (2014 156: 812-824] we measured half-lives of individual mRNA isoforms in Saccharomyces cerevisiae by using the anchor away method for the rapid removal of Rpb1, the largest subunit of RNA Polymerase II, from the nucleus, followed by direct RNA sequencing of the cellular mRNA population over time. Combining these two methods allowed us to determine half-lives for more than 20,000 individual mRNA isoforms originating from nearly 5000 yeast genes. We discovered that different 3’ mRNA isoforms arising from the same gene can have widely different stabilities, and that such half-life variability across mRNA isoforms from a single gene is highly prevalent in yeast cells. Determining half-lives for many different mRNA isoforms from the same genes allowed us to identify hundreds of RNA sequence elements involved in the stabilization and destabilization of individual isoforms. In many cases, the poly(A tail is likely to participate in the formation of stability - enhancing secondary structures at mRNA 3’ ends. Our results point to an important role for mRNA structure at 3’ termini in governing transcript stability, likely by reducing the interaction of the mRNA with the degradation apparatus.

  5. Ivermectin induces P-glycoprotein expression and function through mRNA stabilization in murine hepatocyte cell line.

    Science.gov (United States)

    Ménez, Cécile; Mselli-Lakhal, Laïla; Foucaud-Vignault, Magali; Balaguer, Patrick; Alvinerie, Michel; Lespine, Anne

    2012-01-15

    Ivermectin is widely used in human and veterinary medicine for the control of helminth infections. Ivermectin is known to interact with P-glycoprotein (P-gp/MDR1), being a good substrate and a potent inhibitor, however, the influence of ivermectin on the expression of the transporter has not been investigated. Expression of P-glycoprotein was investigated in cultured mouse hepatocytes acutely exposed to ivermectin. The two P-glycoprotein murine isoforms, Mdr1a and Mdr1b, mRNA levels were assessed by real-time RT-PCR. Ivermectin induced a clear time- and concentration-dependent up-regulation of Mdr1a and Mdr1b mRNA levels (as early as a 12-h exposure and up to 2.5-fold at 10μM). Moreover, ivermectin-treated cells displayed enhanced cellular efflux of the P-glycoprotein substrate calcein that was inhibited by the P-glycoprotein blocker valspodar, providing evidence that the ivermectin-induced P-glycoprotein was functional. The mechanisms underlying these effects were investigated. Ivermectin-mediated Mdr1 mRNA induction was independent of the two nuclear receptors CAR and PXR, which are known to be involved in drug transporters regulation. Moreover, by using reporter cell lines that detects specific ligand-activated transcription factors, we showed that ivermectin did not displayed CAR, PXR or AhR ligand activities. However, studies with actinomycin D revealed that the half-life of Mdr1a and Mdr1b mRNA were significantly prolonged by two-fold in ivermectin-treated cells suggesting a post-transcriptional mode of ivermectin regulation. This study demonstrates for the first time that ivermectin induces P-glycoprotein overexpression through post-transcriptional mRNA stabilization, thus offering insight into the mechanism of reduced therapeutic efficacy and development of ivermectin-resistant parasites.

  6. Pokemon、c-myc在结直肠癌中的表达及意义%EXPRESSION AND CLINICAL SIGNIFICANCE OF POKEMON AND C-MYC IN COLORECTAL CANCER

    Institute of Scientific and Technical Information of China (English)

    刘叔敏; 范玉磊; 梁婷婷; 孙影

    2014-01-01

    目的:探讨结直肠癌组织Pokemon和c-myc蛋白表达的变化和意义。方法:SP免疫组化法检测60例结直肠癌组织和癌旁正常组织Pokemon和c-myc蛋白的表达情况。结果:结直肠癌组织Pokemon和c-myc蛋白的阳性表达率均明显高于正常组织(P<0.01);结直肠癌组织Pokemon和c-myc蛋白的阳性表达与分化程度、Dukes分期和淋巴结转移有关(P<0.01,P<0.05);结直肠癌组织中,Pokemon和c-myc蛋白的表达呈显著正相关(r=0.615,P<0.05)。结论:Pokemon和c-myc对结直肠癌的诊断和预后评判具有一定的价值。%Objective: To investigate the expression and clinical significance of Pokemon and c-myc in human colorectal cancer.Methods: SP immunohistochemical staining was used to detect the expression of Pokemon and c-myc in 60 cases colorectal cancer and matched para-carcinoma tissues.Results:The positive expression rate of Pokemon and c-myc in colorectal cancer were obviously higher than that in normal tissue (P<0.01). In colorectal cancer, the positive expression of Pokemon and c-myc were related with differentiation degree, Dukes stage and lymph node metastasis (P<0.01,P<0.05). The positive expression of Pokemon in colorectal cancer was positively correlated with c-myc expression (r=0.615,P<0.05). Conclusions: Pokemon and c-myc have certain value for diagnosing and prognosis of colorectal cancer.

  7. The function of apoptosis and protein expression of bcl-2, p53 and C-myc inthe development of gastric cancer

    Institute of Scientific and Technical Information of China (English)

    An Gao Xu; Shao Guang Li; Ji Hong Liu; Ai Hua Gan

    2000-01-01

    AIM To understand the rule and possible function of apoptosis and protein expression of bcl-2, p53 and C-myc in chronic gastritis, gastric ulcer, non-classic proliferation of gastric mucosa and gastric cancer.METHODS Apoptosis was detected by using in situ terminal labelling (TUNEL). The protein expression ofbcl-2, p53 and C-myc was detected by immunohistochemical method.RESULTS The indexes of apoptosis in chronic active gastritis, gastric ulcer, mild and severe non-classicproliferation of gastric mucosa, early and progressive gastric cancer were 16.8%±12.3%, 24.1%±20.0%,19.3%±16.4%, 15.7%±15.2%, 10.1%±9.1% and 6.3%±6.0%, respectively. The index of progressivegastric cancer was lower than that of early gastric cancer and non-classic proliferation of gastric mucosa(P<0.05). The positive rate of bcl-2 protein was 9.4%, 27.6%, 52.9%, 75.0%, 83.3% and 46.7%,respectively. The positive rate of bcl-2 of early gastric cancer was higher than that of progressive gastriccancer. The positive rates of p53 protein of severe non-classic proliferation, early and progressive gastriccancer were 25.0%, 33.3% and 63.3%, respectively. The positive rate of p53 of progressive gastric cancerwas higher than that of early gastric cancer and non-classic proliferation (P<0.05). In Lauren types, theindex of apoptosis, protein expression rates of bcl-2, p53 and C-myc of intestinal type were 8.3%±7.2%,38.9%, 77.7% and 56.6%, while that of diffuse type were 5.1%±4.9%, 58.3%, 50.0% and 8.3%,respectively. All markers had statistical difference between two types (P<0.05).CONCLUSION Apoptosis was inhibited stepwise in the development of non-classic proliferation of gastricmucosa to early gastric cancer and then to progressive gastric cancer. The high expression of bcl-2, p53 andC-myc was related to the development of gastric cancer, bcl-2 might play an important role in early gastriccancer while p53 and C-myc act mostly in middle and late stage gastric cancer. The Lauren typing of

  8. Effect of Qi-protecting powder (Huqi San) on expression of c-jun, c-fos and c-myc in diethylnitrosamine-mediated hepatocarcinogenesis

    Institute of Scientific and Technical Information of China (English)

    Xia Li; Zheng-Ming Shi; Ping Feng; Zhao-Yang Wen; Xue-Jiang Wang

    2007-01-01

    AIM: To study the inhibitory effect of Huqi San (Qiprotecting powder) on rat prehepatocarcinoma induced by diethylinitrosamine (DEN) by analyzing the mutational activation of c-fos proto-oncogene and over-expression of c-jun and c-myc oncogenes.METHODS: A Solt-Farber two-step test model of prehepatocarcinoma was induced in rats by DEN and 2-acetylaminofluorene (AAF) to investigate the modifying effects of Huqi San on the expression of c-jun, c-fos and c-myc in DEN-mediated hepatocarcinogenesis. Huqi San was made of eight medicinal herbs containing glycoprival granules, in which each milliliter contains 0.38 g crude drugs. γ-glutamy-transpeptidase-isoenzyme (γ-GTase)was determined with histochemical methods. Level of 8-hydroxydeoxyguanosine (OHdG) formed in liver and c-jun, c-fos and c-myc proto-oncogenes were detected by immunohistochemical methods.RESULTS: The level of 8-OHdG, a mark of oxidative DNA damage, was significantly decreased in the liver of rats with prehepatocarcinoma induced by DEN who received 8 g/kg body weight or 4 g/kg body weight Huqi San before (1 wk) and after DEN exposure (4 wk). Huqi Santreated rats showed a significant decrease in number of γ-GT positive foci (P < 0.001, prevention group: 4.96 ±0.72 vs 29.46 ± 2.17; large dose therapeutic group: 7.53± 0.88 vs 29.46 ± 2.17). On the other hand, significant changes in expression of c-jun, c-fos and c-myc were found in Huqi San-treated rats.CONCLUSION: Activation of c-jun, c-fos and c-myc plays a crucial role in the pathogenesis of liver cancer.Huqi San can inhibit the over-expression of c-jun, c-fos and c-myc oncogenes and liver preneolastic lesionsinduced by DEN.

  9. Role of highly conserved pyrimidine-rich sequences in the 3' untranslated region of the GAP-43 mRNA in mRNA stability and RNA-protein interactions.

    Science.gov (United States)

    Kohn, D T; Tsai, K C; Cansino, V V; Neve, R L; Perrone-Bizzozero, N I

    1996-03-01

    We have shown previously that the mRNA for the growth-associated protein GAP-43 is selectively stabilized during neuronal differentiation. In this study, we explored the role of its highly conserved 3' untranslated region (3'UTR) in mRNA stability and RNA-protein interactions. The 3'UTRs of the rat and chicken GAP-43 mRNAs show 78% sequence identity, which is equivalent to the conservation of their coding regions. In rat PC12 cells stably transfected with the full-length rat or chicken GAP-43 cDNAs, the transgene mRNAs decayed with same half-life of about 3 h. The GAP-43 3'UTR also caused the rabbit beta-globin mRNA to decay with a half-life of 4 h, indicating that the major determinants for GAP-43 mRNA stability are localized in its highly conserved 3'UTR. Three brain cytosolic RNA-binding proteins (molecular mass 40, 65 and 95 kDa) were found to interact with both the rat and chicken GAP-43 mRNAs. These RNA-protein interactions were specific and involved pyrimidine-rich sequences in the 3'UTR. Like the GAP-43 mRNA, the activity of these proteins was enriched in brain and increased during development. We propose that highly conserved pyrimidine-rich sequences in the 3'UTR of this mRNA regulate GAP-43 gene expression via interactions with specific RNA-binding proteins.

  10. c-myc and N-myc promote active stem cell metabolism and cycling as architects of the developing brain.

    Science.gov (United States)

    Wey, Alice; Knoepfler, Paul S

    2010-06-01

    myc genes are associated with a wide variety of human cancers including most types of nervous system tumors. While the mechanisms by which myc overexpression causes tumorigenesis are multifaceted and have yet to be clearly elucidated, they are at least in part related to endogenous myc function in normal cells. Knockout (KO) of either c-myc or N-myc genes in neural stem and precursor cells (NSC) driven by nestin-cre impairs mouse brain growth and mutation of N-myc also causes microcephaly in humans in Feingold Syndrome. To further define myc function in NSC and nervous system development, we created a double KO (DKO) for c- and N-myc using nestin-cre. The DKO mice display profoundly impaired overall brain growth associated with decreased cell cycling and migration of NSC, which are strikingly decreased in number. The DKO brain also exhibits specific changes in gene expression including downregulation of genes involved in protein and nucleotide metabolism, mitosis, and chromatin structure as well as upregulation of genes associated with differentiation. Together these data support a model of nervous system tumorigenesis in which excess myc aberrantly locks in a developmentally active chromatin state characterized by overactive cell cycling, and metabolism as well as blocked differentiation.

  11. Establishment of a human herpes virus-8-negative malignant effusion lymphoma cell line (STR-428) carrying concurrent translocations of BCL2 and c-MYC genes.

    Science.gov (United States)

    Taira, Tamiko; Nagasaki, Akitoshi; Tomoyose, Takeaki; Miyagi, Jun-ichi; Kakazu, Naoki; Makino, Shigeyoshi; Shinjyo, Tetsuharu; Taira, Naoya; Masuda, Masato; Takasu, Nobuyuki

    2007-09-01

    A new cell line, STR-428 was established from ascites tumor cells of a malignant effusion lymphoma patient without human herpes virus-8 (HHV-8) infection. STR-428 cells showed an immunophenotype of mature B-cells and produced few cytokines related to lymphomatous effusion. Karyotypic and genetic analysis revealed complex translocations including t(14;18)(q32;q21) effecting IgH/BCL2 and der(8)t(3;8)(q27;q24) involving c-MYC. STR-428 represents a unique, B-cell lymphoma cell line carrying concurrent rearrangement of BCL2 and c-MYC genes with features distinct from those of HHV-8-related primary effusion lymphoma. This cell line may be a valuable tool, other than HHV-8, to investigate the pathogenesis of primary lymphomatous effusion.

  12. 流体切应力对脑动静脉畸形内皮细胞增殖与c-myc表达的影响%Effect of flow shear stress on endothelial cell proliferation and c-myc expression in cerebral arteriovenous malformation

    Institute of Scientific and Technical Information of China (English)

    赵明光; 李彦兵; 吕博川; 梁勇; 薛洪利; 赵丽萍; 王丹玲

    2007-01-01

    arteriovenous malformation were put in a parallel plate flow chamber. In addition, cells in the low,moderate and high shear stress groups were stressed by low, moderate and high shear stress for 8 hours, respectively.However, shear stress in the control group was 0 Pa. Flow cytometry was used to measure proliferation index, and the expression of c-myc protein and c-myc mRNA were determined by immnocytochemistry and RT-PCR analysis respectively.MAIN OUTCOME MEASURES: Expressions of c-myc protein and c-myc mRNA and proliferation index in endothelial cells under various degrees of shear stress.RESULTS: ① Proliferation index: Proliferation index was higher in the moderate and high shear stress groups than that in the control group (P < 0.05, 0.01). ② Expression of c-myc protein: Immuneposjtjve expression of c-myc protein was gradually increased with the increase of shear stress and there were significant differences in the three shear stress groups as compared with control group (P < 0.05-0.01). ③ Expression of c-myc mRNA: Proliferation index of endothelial cells was higher in the low and moderate shear stress groups than that in the control group (P < 0.05).CONCLUSION: Flow shear stress can induce expression of c-myc and activate expression of c-myc gene based on gene transcription so as to promote the proliferation of vascular endothelial cells in human cerebral arteriovenous malformation%背景:切应力可以直接介导内皮细胞表达一些编码与血管生成相关的细胞因子基因,血液的流体切应力对调节血管结构和功能具有重要的生物学作用.目的:观察流体层流切应力对人脑动静脉畸形血管内皮细胞增殖与原癌基因c-myc表达的影响.设计:随机对照的技术方法.单位:解放军沈阳军区总医院神经外科.对象:实验于2006-11/2007-02在解放军沈阳军区总医院全军神经医学研究所完成.选用2006解放军沈阳军区总医院神经外科Spetzler Ⅱ-Ⅲ级20例脑动静脉畸形

  13. Driving gradual endogenous c-myc overexpression by flow-sorting: intracellular signaling and tumor cell phenotype correlate with oncogene expression

    DEFF Research Database (Denmark)

    Knudsen, Kasper Jermiin; Holm, G.M.N.; Krabbe, J.S.

    2009-01-01

    cells than in the nonsorted cell population. To our knowledge, this is the first in vitro system allowing functional coupling between mitogenic signaling by a well-defined growth factor and gradual overexpression of the normal, endogenous c-myc gene. Thus, our flow-sorting approach provides...... an alternative modeling of the receptor-mediated carcinogenic process, compared to the currently used approaches of recombinant constitutive or conditional overexpression of oncogenic transmembrane receptor tyrosine kinases or oncogenic transcription factors....

  14. Effect of teicoplanin on the expression of c-myc and c-fos proto-oncogenes in MCF-7 breast cancer cell line

    Directory of Open Access Journals (Sweden)

    Saeideh Ashouri

    2016-01-01

    Conclusion: it could be concluded that although teicoplanin is considered as an enhancing cell growth and proliferation, but probably its effect is not through MAP kinase signaling pathway or perhaps even has inhibitory effect on the expression of some genes such as c-myc and c-fos in this pathway. Hence, the mechanism of action of teicoplanin for increasing cell propagation, through cell signaling pathways or chromosomal abnormalities, remains unclear, and further studies should be conducted.

  15. Cytotoxic effect of γ-sitosterol from Kejibeling (Strobilanthes crispus and its mechanism of action towards c-myc gene expression and apoptotic pathway

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    Susi Endrini

    2015-01-01

    Full Text Available Background: This study aimed to analyze the cytotoxicity effect of γ-sitosterol isolated from “Kejibeling” (Strobilanthes crispus, a medicinal plant, on several cancer cell lines. The mechanisms of the effects were studied through the expression of cancer-caused gene, c-myc and apoptotic pathways.Methods: This in vitro study was done using human colon cancer cell lines (Caco-2, liver cancer cell lines (HepG2, hormone-dependent breast cancer cell lines (MCF-7 and the normal liver cell lines (Chang Liver. The cytotoxic effect was measured through MTT assay and the potential cytotoxic value was calculated by determining the toxic concentration which may kill up to 50% of the total cell used (IC50. Meanwhile, the cytotoxic mechanism was studied by determining the effect of adding γ-sitosterol to the c-myc gene expression by reverse transciptase-polymerase chain reaction (RT-PCR. The effect of γ-sitosterol through apoptotic pathway was studied by using terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL assay.Results: γ-sitosterol was cytotoxic against Caco-2, HepG2, and MCF-7 with IC50-values of 8.3, 21.8, and 28.8 μg/mL, respectively. There were no IC50-values obtained from this compound against Chang Liver cell line. This compound induced apotosis on Caco-2 and HepG2 cell lines and suppressed the c-myc genes expression in both cells.Conclusion: γ-sitosterol was cytotoxic against colon and liver cancer cell lines and the effect was mediated by down-regulation of c-myc expression and induction of the apoptotic pathways.

  16. c-myc but not Hif-1α-dependent downregulation of VEGF influences the proliferation and differentiation of HL-60 cells induced by ATRA.

    Science.gov (United States)

    Song, Guanhua; Li, Yanmei; Zhang, Zhiyong; Ren, Xia; Li, Hongjiang; Zhang, Wen; Wei, Ruoying; Pan, Sufei; Shi, Lulu; Bi, Kehong; Jiang, Guosheng

    2013-06-01

    Vascular endothelial growth factor (VEGF) plays an important role in solid tumor growth, progression and metastasis as well as in the proliferation and differentiation of hematological malignancies. However, the molecular mechanism that modulates VEGF expression and secretion in leukemia cells has not yet to be elucidated. The purpose of the present study was to investigate the role of the signal pathway in modulating the expression of VEGF in HL-60 cells. Specific siRNAs targeting VEGF were transfected into HL-60 cells and the VEGF expression was measured with reverse transcription-polymerase chain reaction (RT-PCR) and western blot assay. The cell proliferation of HL-60 cells was detected by the cell counting kit-8 (CCK-8) assay and the differentiation of HL-60 cells induced by all-trans-retinoic acid (ATRA) was detected by the RT-PCR assay and flow cytometry assay for CD11b. The upstream transcription factors that were related to VEGF expression such as P53, SP-1, c-jun, VHL, cox-2, c-myc and stat3 were detected by RT-PCR assay. In addition, the chromatin immunoprecipitation (ChIP) assay was used to reveal the role of c-myc by binding the target gene VEGF. The results demonstrated the hypoxia-inducible factor 1α-related signaling pathway, not the same as in solid tumors, might not play a key role in modulating VEGF expression. c-myc contributes to the modulation of VEGF expression by targeting the promoter of VEGF, which was indicated by the ChIP assay. In conclusion, our data demonstrate that VEGF plays an important role in the differentiation and proliferation of HL-60 cells; c-myc-dependent downregulation of VEGF induced by ATRA contributes to the differentiation of HL-60 cells.

  17. SirT1 knockdown potentiates radiation-induced bystander effect through promoting c-Myc activity and thus facilitating ROS accumulation

    Energy Technology Data Exchange (ETDEWEB)

    Xie, Yuexia [Institute of Radiation Medicine, Fudan University, Shanghai (China); Central Laboratory, Renji Hospital, School of Medicine, Shanghai Jiaotong University, Shanghai (China); Tu, Wenzhi; Zhang, Jianghong; He, Mingyuan; Ye, Shuang; Dong, Chen [Institute of Radiation Medicine, Fudan University, Shanghai (China); Shao, Chunlin, E-mail: clshao@shmu.edu.cn [Institute of Radiation Medicine, Fudan University, Shanghai (China)

    2015-02-15

    Highlights: • γ-Irradiation induced bystander effects between hepatoma cells and hepatocyte cells. • SirT1 played a protective role in regulating this bystander effect. • SirT1 contributed to the protective effects via elimination the accumulation of ROS. • The activity of c-Myc is critical for maintaining the protective role of SirT1. - Abstract: Radiation-induced bystander effect (RIBE) has important implications for secondary cancer risk assessment during cancer radiotherapy, but the bystander signaling processes, especially under hypoxic condition, are still largely unclear. The present study found that micronuclei (MN) formation could be induced in the non-irradiated HL-7702 hepatocyte cells after being treated with the conditioned medium from irradiated hepatoma HepG2 and SK-Hep-1 cells under either normoxia or hypoxia. This bystander response was dramatically diminished or enhanced when the SirT1 gene of irradiated hepatoma cells was overexpressed or knocked down, respectively, especially under hypoxia. Meanwhile, SirT1 knockdown promoted transcriptional activity for c-Myc and facilitated ROS accumulation. But both of the increased bystander responses and ROS generation due to SirT1-knockdown were almost completely suppressed by c-Myc interference. Moreover, ROS scavenger effectively abolished the RIBE triggered by irradiated hepatoma cells even with SirT1 depletion. These findings provide new insights that SirT1 has a profound role in regulating RIBE where a c-Myc-dependent release of ROS may be involved.

  18. Nickel ions selectively inhibit lipopolysaccharide-induced interleukin-6 production by decreasing its mRNA stability.

    Directory of Open Access Journals (Sweden)

    Sanki Asakawa

    Full Text Available Nickel (Ni ions easily elute from many alloys and elicit inflammation and allergies. Previous studies have shown that infections due to the implantation of medical devices cause inflammation and enhance the elution of Ni ions (Ni²⁺. However, cross-talk between infection- and Ni²⁺-induced signaling pathways has not yet been elucidated in detail. In the present study, we investigated the effects of Ni2+ on the lipopolysaccharide (LPS-induced production of cytokines in a LPS-induced air pouch-type inflammation model in BALB/c mice and the murine macrophage cell line RAW264. We demonstrated that Ni²⁺ inhibited the LPS-induced production of interleukin (IL-6, but not that of tumor necrosis factor (TNF-α both in vivo and in vitro. This inhibitory effect was also observed with cobalt ion (Co²⁺, but not with chloride ion (Cl⁻, zinc ion (Zn²⁺, or palladium ion (Pd²⁺, and was highly selective to the production of IL-6. Ni²⁺ did not inhibit the activation of ERK1/2, p38 MAPK, or JNK. Although Ni²⁺ decreased IL-6 mRNA levels, it failed to inhibit the LPS-induced activation of the IL-6 promoter. An experiment using actinomycin D, a transcription inhibitor, revealed that Ni²⁺ decreased the stability of IL-6 mRNA. Moreover, Ni²⁺ inhibited the LPS-induced expression of Arid5a, but not regnase-1. These results demonstrated that Ni²⁺ may have selectively inhibited the LPS-induced production of IL-6 by decreasing the Arid5a-dependent stabilization of IL-6 mRNA.

  19. The Dysregulation of Polyamine Metabolism in Colorectal Cancer Is Associated with Overexpression of c-Myc and C/EBPβ rather than Enterotoxigenic Bacteroides fragilis Infection

    Directory of Open Access Journals (Sweden)

    Anastasiya V. Snezhkina

    2016-01-01

    Full Text Available Colorectal cancer is one of the most common cancers in the world. It is well known that the chronic inflammation can promote the progression of colorectal cancer (CRC. Recently, a number of studies revealed a potential association between colorectal inflammation, cancer progression, and infection caused by enterotoxigenic Bacteroides fragilis (ETBF. Bacterial enterotoxin activates spermine oxidase (SMO, which produces spermidine and H2O2 as byproducts of polyamine catabolism, which, in turn, enhances inflammation and tissue injury. Using qPCR analysis, we estimated the expression of SMOX gene and ETBF colonization in CRC patients. We found no statistically significant associations between them. Then we selected genes involved in polyamine metabolism, metabolic reprogramming, and inflammation regulation and estimated their expression in CRC. We observed overexpression of SMOX, ODC1, SRM, SMS, MTAP, c-Myc, C/EBPβ (CREBP, and other genes. We found that two mediators of metabolic reprogramming, inflammation, and cell proliferation c-Myc and C/EBPβ may serve as regulators of polyamine metabolism genes (SMOX, AZIN1, MTAP, SRM, ODC1, AMD1, and AGMAT as they are overexpressed in tumors, have binding site according to ENCODE ChIP-Seq data, and demonstrate strong coexpression with their targets. Thus, increased polyamine metabolism in CRC could be driven by c-Myc and C/EBPβ rather than ETBF infection.

  20. Diet-induced obesity promotes murine gastric cancer growth through a nampt/sirt1/c-myc positive feedback loop.

    Science.gov (United States)

    Li, Hai-Jun; Che, Xiang-Ming; Zhao, Wei; He, Shi-Cai; Zhang, Zheng-Liang; Chen, Rui; Fan, Lin; Jia, Zong-Liang

    2013-11-01

    Obesity increases the risk of gastric cancer and may promote its growth, as was recently demonstrated by our novel in vivo mouse model. However, the underlying mechanisms of this correlation remain unclear. The purpose of this study was to investigate the precise effects of obesity on gastric cancer growth and to elucidate the potential molecular mechanisms. Diet-induced obese mice were insulin-resistant, glucose-intolerant and had high serum visfatin concentration. In the subcutaneous mouse model, tumors were more aggressive in diet-induced obese mice compared with lean mice. Tumor weights showed a significant positive correlation with mouse body weights, as well as serum insulin and visfatin concentrations. Immunohistochemical staining showed that the expression levels of iNampt, Sirt1 and c-MYC proteins were upregulated in the subcutaneous tumors from obese mice compared to those from lean animals. Furthermore, obesity not only prompted significantly murine forestomach carcinoma cell migration, proliferation, but also affected cellular apoptosis and cell cycle by endocrine mechanisms. These were associated with increased expression of the pro-survival nampt/sirt1/c-myc positive feedback loop confirmed by RT-PCR and western blotting. These results suggested that diet-induced obesity could promote murine gastric cancer growth by upregulating the expression of the nampt, sirt1 and c-myc genes.

  1. Abrupt reduction of c-myc expression by antisense RNA inducing terminal differentiation and apoptosis of a human esophageal cancer cell line

    Institute of Scientific and Technical Information of China (English)

    赵晓航; 王秀琴; 周传农; 彭仁玲; 阎水中; 吴旻

    1995-01-01

    A human esophageal cancer cell line (EC8712) expressing high-level Myc protein was infected with recombmant retroviral particles (pA-BD9) at a multiplicity of infection (MOI) 1:1. This viral particle contains a neomycin-resistant gene and a 1.53-kb antisense RNA spanning the 2nd exon and its flanking sequences of the human c-myc oncogene. The G418-resistant EC8712 clones showed an 86% inhibition of growth rate and morphological changes characteristic of terminal differentiation and apoptosis. A decrease of about 80% of Myc protein was also observed in these infected cells by ABC-ELISA assay. 12-24 h after the infection of ECS712 cells with pA-BD9 at a high viral particle concentration (MOI = 1:10), the integration of the extrinsic 1.53-kb antisense c-myc fragment into the cancer cell genome was evidenced by the Southern blot analysis. Northern blot analyses showed the expression of this antisense fragment and a decrease of the intrinsic c-myc expression by 74% in comparison with that of the parental EC8

  2. A Novel PTEN/Mutant p53/c-Myc/Bcl-XL Axis Mediates Context-Dependent Oncogenic Effects of PTEN with Implications for Cancer Prognosis and Therapy

    Directory of Open Access Journals (Sweden)

    Xiaoping Huang

    2013-08-01

    Full Text Available Phosphatase and tensin homolog located on chromosome 10 (PTEN is one of the most frequently mutated tumor suppressors in human cancer including in glioblastoma. Here, we show that PTEN exerts unconventional oncogenic effects in glioblastoma through a novel PTEN/mutant p53/c-Myc/Bcl-XL molecular and functional axis. Using a wide array of molecular, genetic, and functional approaches, we demonstrate that PTEN enhances a transcriptional complex containing gain-of-function mutant p53, CBP, and NFY in human glioblastoma cells and tumor tissues. The mutant p53/CBP/NFY complex transcriptionally activates the oncogenes c-Myc and Bcl-XL, leading to increased cell proliferation, survival, invasion, and clonogenicity. Disruption of the mutant p53/c-Myc/Bcl-XL axis or mutant p53/CBP/NFY complex reverses the transcriptional and oncogenic effects of PTEN and unmasks its tumor-suppressive function. Consistent with these data, we find that PTEN expression is associated with worse patient survival than PTEN loss in tumors harboring mutant p53 and that a small molecule modulator of p53 exerts greater antitumor effects in PTEN-expressing cancer cells. Altogether, our study describes a new signaling pathway that mediates context-dependent oncogenic/tumor-suppressive role of PTEN. The data also indicate that the combined mutational status of PTEN and p53 influences cancer prognosis and anticancer therapies that target PTEN and p53.

  3. cMyc/miR-125b-5p signalling determines sensitivity to bortezomib in preclinical model of cutaneous T-cell lymphomas.

    Directory of Open Access Journals (Sweden)

    Valentina Manfè

    Full Text Available Successful/effective cancer therapy in low grade lymphoma is often hampered by cell resistance to anti-neoplastic agents. The crucial mechanisms responsible for this phenomenon are poorly understood. Overcoming resistance of tumor cells to anticancer agents, such as proteasome inhibitors, could improve their