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Sample records for increased myc gene

  1. Colorimetric In Situ Hybridization Identifies MYC Gene Signal Clusters Correlating With Increased Copy Number, mRNA, and Protein in Diffuse Large B-cell Lymphoma

    PubMed Central

    Valentino, Carlo; Kendrick, Samantha; Johnson, Nathalie; Gascoyne, Randy; Chan, Wing C.; Weisenburger, Dennis; Braziel, Rita; Cook, James R.; Tubbs, Raymond; Campo, Elias; Rosenwald, Andreas; Ott, German; Delabie, Jan; Jaffe, Elaine; Zhang, Wenjun; Brunhoeber, Patrick; Nitta, Hiro; Grogan, Tom; Rimsza, Lisa

    2014-01-01

    Abnormalities of the MYC oncogene on chromosome 8 are characteristic of Burkitt lymphoma and other aggressive B-cell lymphomas, including diffuse large B-cell lymphoma (DLBCL). We recently described a colorimetric in situ hybridization (CISH) method for detecting extra copies of the MYC gene in DLBCL and the frequent occurrence of excess copies of discrete MYC signals in the context of diploidy or polyploidy of chromosome 8, which correlated with increased mRNA signals. We further observed enlarged MYC signals, which were counted as a single gene copy but, by their dimension and unusual shape, likely consisted of “clusters” of MYC genes. In this study, we sought to further characterize these clusters of MYC signals by determining whether the presence of these correlated with other genetic features, mRNA levels, protein, and overall survival. We found that MYC clusters correlated with an abnormal MYC locus and with increased mRNA. MYC mRNA correlated with protein levels, and both increased mRNA and protein correlated with poorer overall survival. MYC clusters were seen in both the germinal center and activated B-cell subtypes of DLBCL. Clusters of MYC signals may be an underappreciated, but clinically important, feature of aggressive B-cell lymphomas with potential prognostic and therapeutic relevance. PMID:23355209

  2. Reduced expression of MYC increases longevity and enhances healthspan.

    PubMed

    Hofmann, Jeffrey W; Zhao, Xiaoai; De Cecco, Marco; Peterson, Abigail L; Pagliaroli, Luca; Manivannan, Jayameenakshi; Hubbard, Gene B; Ikeno, Yuji; Zhang, Yongqing; Feng, Bin; Li, Xiaxi; Serre, Thomas; Qi, Wenbo; Van Remmen, Holly; Miller, Richard A; Bath, Kevin G; de Cabo, Rafael; Xu, Haiyan; Neretti, Nicola; Sedivy, John M

    2015-01-29

    MYC is a highly pleiotropic transcription factor whose deregulation promotes cancer. In contrast, we find that Myc haploinsufficient (Myc(+/-)) mice exhibit increased lifespan. They show resistance to several age-associated pathologies, including osteoporosis, cardiac fibrosis, and immunosenescence. They also appear to be more active, with a higher metabolic rate and healthier lipid metabolism. Transcriptomic analysis reveals a gene expression signature enriched for metabolic and immune processes. The ancestral role of MYC as a regulator of ribosome biogenesis is reflected in reduced protein translation, which is inversely correlated with longevity. We also observe changes in nutrient and energy sensing pathways, including reduced serum IGF-1, increased AMPK activity, and decreased AKT, TOR, and S6K activities. In contrast to observations in other longevity models, Myc(+/-) mice do not show improvements in stress management pathways. Our findings indicate that MYC activity has a significant impact on longevity and multiple aspects of mammalian healthspan. PMID:25619689

  3. Reduced Expression of MYC Increases Longevity and Enhances Healthspan

    PubMed Central

    Hofmann, Jeffrey W.; Zhao, Xiaoai; De Cecco, Marco; Peterson, Abigail L.; Pagliaroli, Luca; Manivannan, Jayameenakshi; Hubbard, Gene B.; Ikeno, Yuji; Zhang, Yongqing; Feng, Bin; Li, Xiaxi; Serre, Thomas; Qi, Wenbo; Van Remmen, Holly; Miller, Richard A.; Bath, Kevin G.; de Cabo, Rafael; Xu, Haiyan; Neretti, Nicola; Sedivy, John M.

    2015-01-01

    SUMMARY MYC is a highly pleiotropic transcription factor whose deregulation promotes cancer. In contrast, we find that Myc haploinsufficient (Myc+/−) mice exhibit increased lifespan. They show resistance to several age-associated pathologies, including osteoporosis, cardiac fibrosis and immunosenescence. They also appear to be more active, with a higher metabolic rate and healthier lipid metabolism. Transcriptomic analysis reveals a gene expression signature enriched for metabolic and immune processes. The ancestral role of MYC as a regulator of ribosome biogenesis is reflected in reduced protein translation, which is inversely correlated with longevity. We also observe changes in nutrient and energy sensing pathways, including reduced serum IGF-1, increased AMPK activity, and decreased AKT, TOR and S6K activities. In contrast to observations in other longevity models, Myc+/− mice do not show improvements in stress management pathways. Our findings indicate that MYC activity has a significant impact on longevity and multiple aspects of mammalian healthspan. PMID:25619689

  4. Increases in iPS Transcription Factor (Oct4, Sox2, c-Myc, and Klf4) Gene Expression after Modified Electroconvulsive Therapy

    PubMed Central

    Nishiguchi, Masaki; Kanazawa, Tetsufumi; Tsutsumi, Atsushi; Kaneko, Takao; Uenishi, Hiroyuki; Kawabata, Yasuo; Kawashige, Seiya; Koh, Jun; Yoneda, Hiroshi

    2015-01-01

    Objective Electroconvulsive therapy (ECT) is a reasonable option for intractable depression or schizophrenia, but a mechanism of action has not been established. One credible hypothesis is related to neural plasticity. Three genes (Oct4, Sox2, c-Myc) involved in the induction of induced pluripotent stem (iPS) cells are Wnt-target genes, which constitute a key gene group involved in neural plasticity through the TCF family. Klf4 is the other gene among Yamanaka's four transcription factors, and increases in its expression are induced by stimulation of the canonical Wnt pathway. Methods We compared the peripheral blood gene expression of the four iPS genes (Oct4, Sox2, c-Myc, and Klf4) before and after modified ECT (specifically ECT with general anesthesia) of patients with intractable depression (n=6) or schizophrenia (n=6). Using Thymatron ten times the total bilateral electrical stimulation was evoked. Results Both assessments of the symptoms demonstrated significant improvement after mECT stimulation. Expression of all four genes was confirmed to increase after initial stimulation. The gene expression levels after treatment were significantly different from the initial gene expression in all twelve cases at the following treatment stages: at the 3rd mECT for Oct4; at the 6th and 10th mECT for Sox2; and at the 3rd, 6th and 10th mECT for c-Myc. Conclusion These significant differences were not present after correction for multiple testing; however, our data have the potential to explain the molecular mechanisms of mECT from a unique perspective. Further studie should be conducted to clarify the pathophysiological involvement of iPS-inducing genes in ECT. PMID:26508965

  5. Nuclear AXIN2 represses MYC gene expression

    SciTech Connect

    Rennoll, Sherri A.; Konsavage, Wesley M.; Yochum, Gregory S.

    2014-01-03

    Highlights: •AXIN2 localizes to cytoplasmic and nuclear compartments in colorectal cancer cells. •Nuclear AXIN2 represses the activity of Wnt-responsive luciferase reporters. •β-Catenin bridges AXIN2 to TCF transcription factors. •AXIN2 binds the MYC promoter and represses MYC gene expression. -- Abstract: The β-catenin transcriptional coactivator is the key mediator of the canonical Wnt signaling pathway. In the absence of Wnt, β-catenin associates with a cytosolic and multi-protein destruction complex where it is phosphorylated and targeted for proteasomal degradation. In the presence of Wnt, the destruction complex is inactivated and β-catenin translocates into the nucleus. In the nucleus, β-catenin binds T-cell factor (TCF) transcription factors to activate expression of c-MYC (MYC) and Axis inhibition protein 2 (AXIN2). AXIN2 is a member of the destruction complex and, thus, serves in a negative feedback loop to control Wnt/β-catenin signaling. AXIN2 is also present in the nucleus, but its function within this compartment is unknown. Here, we demonstrate that AXIN2 localizes to the nuclei of epithelial cells within normal and colonic tumor tissues as well as colorectal cancer cell lines. In the nucleus, AXIN2 represses expression of Wnt/β-catenin-responsive luciferase reporters and forms a complex with β-catenin and TCF. We demonstrate that AXIN2 co-occupies β-catenin/TCF complexes at the MYC promoter region. When constitutively localized to the nucleus, AXIN2 alters the chromatin structure at the MYC promoter and directly represses MYC gene expression. These findings suggest that nuclear AXIN2 functions as a rheostat to control MYC expression in response to Wnt/β-catenin signaling.

  6. Nuclear AXIN2 represses MYC gene expression.

    PubMed

    Rennoll, Sherri A; Konsavage, Wesley M; Yochum, Gregory S

    2014-01-01

    The β-catenin transcriptional coactivator is the key mediator of the canonical Wnt signaling pathway. In the absence of Wnt, β-catenin associates with a cytosolic and multi-protein destruction complex where it is phosphorylated and targeted for proteasomal degradation. In the presence of Wnt, the destruction complex is inactivated and β-catenin translocates into the nucleus. In the nucleus, β-catenin binds T-cell factor (TCF) transcription factors to activate expression of c-MYC (MYC) and Axis inhibition protein 2 (AXIN2). AXIN2 is a member of the destruction complex and, thus, serves in a negative feedback loop to control Wnt/β-catenin signaling. AXIN2 is also present in the nucleus, but its function within this compartment is unknown. Here, we demonstrate that AXIN2 localizes to the nuclei of epithelial cells within normal and colonic tumor tissues as well as colorectal cancer cell lines. In the nucleus, AXIN2 represses expression of Wnt/β-catenin-responsive luciferase reporters and forms a complex with β-catenin and TCF. We demonstrate that AXIN2 co-occupies β-catenin/TCF complexes at the MYC promoter region. When constitutively localized to the nucleus, AXIN2 alters the chromatin structure at the MYC promoter and directly represses MYC gene expression. These findings suggest that nuclear AXIN2 functions as a rheostat to control MYC expression in response to Wnt/β-catenin signaling. PMID:24299953

  7. Activation and repression by oncogenic MYC shape tumour-specific gene expression profiles.

    PubMed

    Walz, Susanne; Lorenzin, Francesca; Morton, Jennifer; Wiese, Katrin E; von Eyss, Björn; Herold, Steffi; Rycak, Lukas; Dumay-Odelot, Hélène; Karim, Saadia; Bartkuhn, Marek; Roels, Frederik; Wüstefeld, Torsten; Fischer, Matthias; Teichmann, Martin; Zender, Lars; Wei, Chia-Lin; Sansom, Owen; Wolf, Elmar; Eilers, Martin

    2014-07-24

    In mammalian cells, the MYC oncoprotein binds to thousands of promoters. During mitogenic stimulation of primary lymphocytes, MYC promotes an increase in the expression of virtually all genes. In contrast, MYC-driven tumour cells differ from normal cells in the expression of specific sets of up- and downregulated genes that have considerable prognostic value. To understand this discrepancy, we studied the consequences of inducible expression and depletion of MYC in human cells and murine tumour models. Changes in MYC levels activate and repress specific sets of direct target genes that are characteristic of MYC-transformed tumour cells. Three factors account for this specificity. First, the magnitude of response parallels the change in occupancy by MYC at each promoter. Functionally distinct classes of target genes differ in the E-box sequence bound by MYC, suggesting that different cellular responses to physiological and oncogenic MYC levels are controlled by promoter affinity. Second, MYC both positively and negatively affects transcription initiation independent of its effect on transcriptional elongation. Third, complex formation with MIZ1 (also known as ZBTB17) mediates repression of multiple target genes by MYC and the ratio of MYC and MIZ1 bound to each promoter correlates with the direction of response. PMID:25043018

  8. Mechanism of endogenous myc gene down-regulation in E mu-N-myc tumors.

    PubMed

    Ma, A; Smith, R K; Tesfaye, A; Achacoso, P; Dildrop, R; Rosenberg, N; Alt, F W

    1991-01-01

    Transgenic mouse lines carrying the N-myc oncogene deregulated by the immunoglobulin heavy-chain enhancer spontaneously develop B-lymphoid tumors (R. Dildrop, A. Ma, K. Zimmerman, E. Hsu, A. Tesfaye, R. DePinho, and F. W. Alt, EMBO J. 8:1121-1128, 1989; H. Rosenbaum, E. Webb, J. M. Adams, S. Cory, and A. W. Harris, EMBO J. 8:749-755). Permanent cell lines derived from these tumors (E mu-N-myc cell lines) express extremely high levels of the N-myc transgene but little or no detectable endogenous N-myc or c-myc. We have employed nuclear run-on assays to show that down-regulation of endogenous N- and c-myc expression occurs at the transcriptional level. To determine whether the lack of endogenous myc gene transcription is a direct effect of high-level N-myc transgene expression, we have generated Abelson murine leukemia virus (A-MuLV)-transformed cell lines from prelymphomatous E mu-N-myc mice (A-MuLV/E mu-N-myc cell lines). Although these A-MuLV/E mu-N-myc lines express very high levels of the N-myc transgene, they continue to transcribe the endogenous c-myc gene. These findings demonstrate that high-level N-myc gene expression alone does not necessarily lead to down-regulation of endogenous myc gene expression and suggest that events associated with transformation by N-myc may be critical to this process. PMID:1986238

  9. An alternative pathway for gene regulation by Myc.

    PubMed Central

    Peukert, K; Staller, P; Schneider, A; Carmichael, G; Hänel, F; Eilers, M

    1997-01-01

    The c-Myc protein activates transcription as part of a heteromeric complex with Max. However, Myc-transformed cells are characterized by loss of expression of several genes, suggesting that Myc may also repress gene expression. Two-hybrid cloning identifies a novel POZ domain Zn finger protein (Miz-1; Myc-interacting Zn finger protein-1) that specifically interacts with Myc, but not with Max or USF. Miz-1 binds to start sites of the adenovirus major late and cyclin D1 promoters and activates transcription from both promoters. Miz-1 has a potent growth arrest function. Binding of Myc to Miz-1 requires the helix-loop-helix domain of Myc and a short amphipathic helix located in the carboxy-terminus of Miz-1. Expression of Myc inhibits transactivation, overcomes Miz-1-induced growth arrest and renders Miz-1 insoluble in vivo. These processes depend on Myc and Miz-1 association and on the integrity of the POZ domain of Miz-1, suggesting that Myc binding activates a latent inhibitory function of this domain. Fusion of a nuclear localization signal induces efficient nuclear transport of Miz-1 and impairs the ability of Myc to overcome transcriptional activation and growth arrest by Miz-1. Our data suggest a model for how gene repression by Myc may occur in vivo. PMID:9312026

  10. MYCN/c-MYC-induced microRNAs repress coding gene networks associated with poor outcome in MYCN/c-MYC-activated tumors.

    PubMed

    Mestdagh, P; Fredlund, E; Pattyn, F; Schulte, J H; Muth, D; Vermeulen, J; Kumps, C; Schlierf, S; De Preter, K; Van Roy, N; Noguera, R; Laureys, G; Schramm, A; Eggert, A; Westermann, F; Speleman, F; Vandesompele, J

    2010-03-01

    Increased activity of MYC protein-family members is a common feature in many cancers. Using neuroblastoma as a tumor model, we established a microRNA (miRNA) signature for activated MYCN/c-MYC signaling in two independent primary neuroblastoma tumor cohorts and provide evidence that c-MYC and MYCN have overlapping functions. On the basis of an integrated approach including miRNA and messenger RNA (mRNA) gene expression data we show that miRNA activation contributes to widespread mRNA repression, both in c-MYC- and MYCN-activated tumors. c-MYC/MYCN-induced miRNA activation was shown to be dependent on c-MYC/MYCN promoter binding as evidenced by chromatin immunoprecipitation. Finally, we show that pathways, repressed through c-MYC/MYCN miRNA activation, are highly correlated to tumor aggressiveness and are conserved across different tumor entities suggesting that c-MYC/MYCN activate a core set of miRNAs for cooperative repression of common transcriptional programs related to disease aggressiveness. Our results uncover a widespread correlation between miRNA activation and c-MYC/MYCN-mediated coding gene expression modulation and further substantiate the overlapping functions of c-MYC and MYCN in the process of tumorigenesis. PMID:19946337

  11. Burkitt’s lymphoma-associated c-Myc mutations converge on a dramatically altered target gene response and implicate Nol5a/Nop56 in oncogenesis

    PubMed Central

    Cowling, Victoria H.; Turner, Scott A.; Cole, Michael D.

    2016-01-01

    Burkitt’s Lymphomas (BLs) acquire consistent point mutations in a conserved domain of Myc, Myc Box I. We report that the enhanced transforming activity of BL-associated Myc mutants can be uncoupled from loss of phosphorylation and increased protein stability. Furthermore, two different BL-associated Myc mutations induced similar gene expression profiles independently of T58 phosphorylation, and these profiles are dramatically different from MycWT. Nol5a/Nop56, which is required for rRNA methylation, was identified as a gene hyperactivated by the BL-associated Myc mutants. We show that Nol5a is necessary for Myc-induced cell transformation, enhances MycWT-induced cell transformation, and increases the size of MycWT induced tumors. Thus, Nol5a expands the link between Myc-induced regulation of nucleolar target genes which are rate-limiting for cell transformation and tumor growth. PMID:24013231

  12. PVT1 dependence in cancer with MYC copy-number increase

    PubMed Central

    Tseng, Yuen-Yi; Moriarity, Branden S.; Gong, Wuming; Akiyama, Ryutaro; Tiwari, Ashutosh; Kawakami, Hiroko; Ronning, Peter; Reuland, Brian; Guenther, Kacey; Beadnell, Thomas C.; Essig, Jaclyn; Otto, George M.; O’Sullivan, M. Gerard; Largaespada, David A.; Schwertfeger, Kathryn L.; Marahrens, York; Kawakami, Yasuhiko; Bagchi, Anindya

    2016-01-01

    ‘Gain’ of supernumerary copies of the 8q24.21 chromosomal region has been shown to be common in many human cancers1–13 and is associated with poor prognosis7,10,14. The well-characterized myelocytomatosis (MYC) oncogene resides in the 8q24.21 region and is consistently co-gained with an adjacent ‘gene desert’ of approximately 2 megabases that contains the long non-coding RNA gene PVT1, the CCDC26 gene candidate and the GSDMC gene. Whether low copy-number gain of one or more of these genes drives neoplasia is not known. Here we use chromosome engineering in mice to show that a single extra copy of either the Myc gene or the region encompassing Pvt1, Ccdc26 and Gsdmc fails to advance cancer measurably, whereas a single supernumerary segment encompassing all four genes successfully promotes cancer. Gain of PVT1 long non-coding RNA expression was required for high MYC protein levels in 8q24-amplified human cancer cells. PVT1 RNA and MYC protein expression correlated in primary human tumours, and copy number of PVT1 was co-increased in more than 98% of MYC-copy-increase cancers. Ablation of PVT1 from MYC-driven colon cancer line HCT116 diminished its tumorigenic potency. As MYC protein has been refractory to small-molecule inhibition, the dependence of high MYC protein levels on PVT1 long non-coding RNA provides a much needed therapeutic target. PMID:25043044

  13. Deciphering c-MYC-regulated genes in two distinct tissues

    PubMed Central

    2011-01-01

    Background The transcription factor MYC is a critical regulator of diverse cellular processes, including both replication and apoptosis. Differences in MYC-regulated gene expression responsible for such opposing outcomes in vivo remain obscure. To address this we have examined time-dependent changes in global gene expression in two transgenic mouse models in which MYC activation, in either skin suprabasal keratinocytes or pancreatic islet β-cells, promotes tissue expansion or involution, respectively. Results Consistent with observed phenotypes, expression of cell cycle genes is increased in both models (albeit enriched in β-cells), as are those involved in cell growth and metabolism, while expression of genes involved in cell differentiation is down-regulated. However, in β-cells, which unlike suprabasal keratinocytes undergo prominent apoptosis from 24 hours, there is up-regulation of genes associated with DNA-damage response and intrinsic apoptotic pathways, including Atr, Arf, Bax and Cycs. In striking contrast, this is not the case for suprabasal keratinocytes, where pro-apoptotic genes such as Noxa are down-regulated and key anti-apoptotic pathways (such as Igf1-Akt) and those promoting angiogenesis are up-regulated. Moreover, dramatic up-regulation of steroid hormone-regulated Kallikrein serine protease family members in suprabasal keratinocytes alone could further enhance local Igf1 actions, such as through proteolysis of Igf1 binding proteins. Conclusions Activation of MYC causes cell growth, loss of differentiation and cell cycle entry in both β-cells and suprabasal keratinocytes in vivo. Apoptosis, which is confined to β-cells, may involve a combination of a DNA-damage response and downstream activation of pro-apoptotic signalling pathways, including Cdc2a and p19Arf/p53, and downstream targets. Conversely, avoidance of apoptosis in suprabasal keratinocytes may result primarily from the activation of key anti-apoptotic signalling pathways

  14. Drosophila Myc is required for normal DREF gene expression

    SciTech Connect

    Dang Thi Phuong Thao; Seto, Hirokazu; Yamaguchi, Masamitsu

    2008-01-01

    The Drosophila DNA replication-related element-binding factor (dDREF) is required for the expression of many proliferation-related genes carrying the DRE sequence, 5'-TATCGATA. Finding a canonical E-box, 5'-CACGTG, in the dDREF gene promoter prompted us to explore the possibility that the dDREF gene is a target of Drosophila Myc (dMyc). Luciferase transient expression assays combined with RNA interference in Drosophila S2 cells revealed that knockdown of dmyc reduced dDREF gene promoter activity by 35% to 82%, an effect at least partly mediated by the E-box in the promoter. dm{sup 4}/Y hemizygous mutant larvae demonstrated no maternal dMyc and severe impairment of dDREF mRNA transcription. dMyc loss of function in dm{sup 2}/dm{sup 2} homozygous mutant follicle cell clones also resulted in loss of anti-dDREF immunostaining in nuclei. In contrast, co-expression of dMyc-dMax up-regulated dDREF promoter activity in S2 cells. Furthermore, dMyc over-expressing clones exhibited a high level of dDREF gene expression in wing and eye discs. These results taken together indicate that dMyc is indeed required for dDREF gene expression.

  15. Hydra myc2, a unique pre-bilaterian member of the myc gene family, is activated in cell proliferation and gametogenesis.

    PubMed

    Hartl, Markus; Glasauer, Stella; Valovka, Taras; Breuker, Kathrin; Hobmayer, Bert; Bister, Klaus

    2014-01-01

    The myc protooncogene encodes the Myc transcription factor which is the essential part of the Myc-Max network controlling fundamental cellular processes. Deregulation of myc leads to tumorigenesis and is a hallmark of many human cancers. We have recently identified homologs of myc (myc1, myc2) and max in the early diploblastic cnidarian Hydra and have characterized myc1 in detail. Here we show that myc2 is transcriptionally activated in the interstitial stem cell system. Furthermore, in contrast to myc1, myc2 expression is also detectable in proliferating epithelial stem cells throughout the gastric region. myc2 but not myc1 is activated in cycling precursor cells during early oogenesis and spermatogenesis, suggesting that the Hydra Myc2 protein has a possible non-redundant function in cell cycle progression. The Myc2 protein displays the principal design and properties of vertebrate Myc proteins. In complex with Max, Myc2 binds to DNA with similar affinity as Myc1-Max heterodimers. Immunoprecipitation of Hydra chromatin revealed that both Myc1 and Myc2 bind to the enhancer region of CAD, a classical Myc target gene in mammals. Luciferase reporter gene assays showed that Myc1 but not Myc2 transcriptionally activates the CAD promoter. Myc2 has oncogenic potential when tested in primary avian fibroblasts but to a lower degree as compared to Myc1. The identification of an additional myc gene in Cnidaria, a phylum that diverged prior to bilaterians, with characteristic expression patterns in tissue homeostasis and developmental processes suggests that principle functions of myc genes have arisen very early in metazoan evolution. PMID:24771621

  16. Hydra myc2, a unique pre-bilaterian member of the myc gene family, is activated in cell proliferation and gametogenesis

    PubMed Central

    Hartl, Markus; Glasauer, Stella; Valovka, Taras; Breuker, Kathrin; Hobmayer, Bert; Bister, Klaus

    2014-01-01

    ABSTRACT The myc protooncogene encodes the Myc transcription factor which is the essential part of the Myc–Max network controlling fundamental cellular processes. Deregulation of myc leads to tumorigenesis and is a hallmark of many human cancers. We have recently identified homologs of myc (myc1, myc2) and max in the early diploblastic cnidarian Hydra and have characterized myc1 in detail. Here we show that myc2 is transcriptionally activated in the interstitial stem cell system. Furthermore, in contrast to myc1, myc2 expression is also detectable in proliferating epithelial stem cells throughout the gastric region. myc2 but not myc1 is activated in cycling precursor cells during early oogenesis and spermatogenesis, suggesting that the Hydra Myc2 protein has a possible non-redundant function in cell cycle progression. The Myc2 protein displays the principal design and properties of vertebrate Myc proteins. In complex with Max, Myc2 binds to DNA with similar affinity as Myc1–Max heterodimers. Immunoprecipitation of Hydra chromatin revealed that both Myc1 and Myc2 bind to the enhancer region of CAD, a classical Myc target gene in mammals. Luciferase reporter gene assays showed that Myc1 but not Myc2 transcriptionally activates the CAD promoter. Myc2 has oncogenic potential when tested in primary avian fibroblasts but to a lower degree as compared to Myc1. The identification of an additional myc gene in Cnidaria, a phylum that diverged prior to bilaterians, with characteristic expression patterns in tissue homeostasis and developmental processes suggests that principle functions of myc genes have arisen very early in metazoan evolution. PMID:24771621

  17. Arabidopsis MYC2 Interacts with DELLA Proteins in Regulating Sesquiterpene Synthase Gene Expression[W][OA

    PubMed Central

    Hong, Gao-Jie; Xue, Xue-Yi; Mao, Ying-Bo; Wang, Ling-Jian; Chen, Xiao-Ya

    2012-01-01

    Arabidopsis thaliana flowers emit volatile terpenes, which may function in plant–insect interactions. Here, we report that Arabidopsis MYC2, a basic helix-loop-helix transcription factor, directly binds to promoters of the sesquiterpene synthase genes TPS21 and TPS11 and activates their expression. Expression of TPS21 and TPS11 can be induced by the phytohormones gibberellin (GA) and jasmonate (JA), and both inductions require MYC2. The induction of TPS21 and TPS11 results in increased emission of sesquiterpene, especially (E)-β-caryophyllene. DELLAs, the GA signaling repressors, negatively affect sesquiterpene biosynthesis, as the sesquiterpene synthase genes were repressed in plants overaccumulating REPRESSOR OF GA1-3 (RGA), one of the Arabidopsis DELLAs, and upregulated in a penta DELLA-deficient mutant. Yeast two-hybrid and coimmunoprecipitation assays demonstrated that DELLAs, represented by RGA, directly interact with MYC2. In yeast cells, the N terminus of MYC2 was responsible for binding to RGA. MYC2 has been proposed as a major mediator of JA signaling and crosstalk with abscisic acid, ethylene, and light signaling pathways. Our results demonstrate that MYC2 is also connected to GA signaling in regulating a subset of genes. In Arabidopsis inflorescences, it integrates both GA and JA signals into transcriptional regulation of sesquiterpene synthase genes and promotes sesquiterpene production. PMID:22669881

  18. INSM1 increases N-myc stability and oncogenesis via a positive-feedback loop in neuroblastoma.

    PubMed

    Chen, Chiachen; Breslin, Mary B; Lan, Michael S

    2015-11-01

    Insulinoma associated-1 (IA-1/INSM1) gene is exclusively expressed during early embryonic development, but has been found to be re-expressed at high levels in neuroendocrine tumors including neuroblastoma. Using over-expression and knockdown experiments in neuroblastoma cells, we showed that INSM1 is critical for cell proliferation, BME-coated invasion, and soft agar colony formation. Here, we identified INSM1 as a novel target gene activated by N-myc in N-myc amplified neuroblastoma cells. The Sonic hedgehog signaling pathway induced INSM1 by increasing N-myc expression. INSM1 activated PI3K/AKT/GSK3β pathways to suppress N-myc phosphorylation (Thr-58) and inhibited degradation of N-myc. Inversely, N-myc protein bound to the E2-box region of the INSM1 promoter and activated INSM1 expression. The invasion assay and the xenograft nude mouse tumor model revealed that the INSM1 factor facilitated growth and oncogenesis of neuroblastoma. The current data supports our hypothesis that a positive-feedback loop of sonic hedgehog signaling induced INSM1 through N-myc and INSM1 enhanced N-myc stability contributing to the transformation of human neuroblastoma. PMID:26456864

  19. INSM1 increases N-myc stability and oncogenesis via a positive-feedback loop in neuroblastoma

    PubMed Central

    Chen, Chiachen; Breslin, Mary B.; Lan, Michael S.

    2015-01-01

    Insulinoma associated-1 (IA-1/INSM1) gene is exclusively expressed during early embryonic development, but has been found to be re-expressed at high levels in neuroendocrine tumors including neuroblastoma. Using over-expression and knockdown experiments in neuroblastoma cells, we showed that INSM1 is critical for cell proliferation, BME-coated invasion, and soft agar colony formation. Here, we identified INSM1 as a novel target gene activated by N-myc in N-myc amplified neuroblastoma cells. The Sonic hedgehog signaling pathway induced INSM1 by increasing N-myc expression. INSM1 activated PI3K/AKT/GSK3β pathways to suppress N-myc phosphorylation (Thr-58) and inhibited degradation of N-myc. Inversely, N-myc protein bound to the E2-box region of the INSM1 promoter and activated INSM1 expression. The invasion assay and the xenograft nude mouse tumor model revealed that the INSM1 factor facilitated growth and oncogenesis of neuroblastoma. The current data supports our hypothesis that a positive-feedback loop of sonic hedgehog signaling induced INSM1 through N-myc and INSM1 enhanced N-myc stability contributing to the transformation of human neuroblastoma. PMID:26456864

  20. Amino-terminal domains of c-myc and N-myc proteins mediate binding to the retinoblastoma gene product

    NASA Astrophysics Data System (ADS)

    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.

  1. Increased metastasis with loss of E2F2 in Myc-driven tumors

    PubMed Central

    Yuwanita, Inez; Barnes, Danielle; Monterey, Michael D.; O'Reilly, Sandra; Andrechek, Eran R.

    2015-01-01

    In human breast cancer, mortality is associated with metastasis to distant sites. Therefore, it is critical to elucidate the biological mechanisms that underlie tumor progression and metastasis. Using signaling pathway signatures we previously predicted a role for E2F transcription factors in Myc induced tumors. To test this role we interbred MMTV-Myc transgenic mice with E2F knockouts. Surprisingly, we observed that the loss of E2F2 sharply increased the percentage of lung metastasis in MMTV-Myc transgenic mice. Examining the gene expression profile from these tumors, we identified genetic components that were potentially involved in mediating metastasis. These genes were filtered to uncover the genes involved in metastasis that also impacted distant metastasis free survival in human breast cancer. In order to elucidate the mechanism by which E2F2 loss enhanced metastasis we generated knockdowns of E2F2 in MDA-MB-231 cells and observed increased migration in vitro and increased lung colonization in vivo. We then examined genes that were differentially regulated between tumors from MMTV-Myc, MMTV-Myc E2F2−/−, and lung metastases samples and identified PTPRD. To test the role of PTPRD in E2F2-mediated breast cancer metastasis, we generated a knockdown of PTPRD in MDA-MB-231 cells. We noted that decreased levels of PTPRD resulted in decreased migration in vitro and decreased lung colonization in vivo. Taken together, these data indicate that E2F2 loss results in increased metastasis in breast cancer, potentially functioning through a PTPRD dependent mechanism. PMID:26474282

  2. c-Myc is a universal amplifier of expressed genes in lymphocytes and embryonic stem cells

    PubMed Central

    Nie, Zuqin; Hu, Gangqing; Wei, Gang; Cui, Kairong; Yamane, Arito; Resch, Wolfgang; Wang, Ruoning; Green, Douglas R.; Tessarollo, Lino; Casellas, Rafael; Zhao, Keji; Levens, David

    2012-01-01

    Summary The c-Myc HLH-bZIP protein has been implicated in physiological or pathological growth, proliferation, apoptosis, metabolism and differentiation at the cellular, tissue or organismal levels via regulation of numerous target genes. No principle yet unifies Myc action due partly to an incomplete inventory and functional accounting of Myc’s targets. To observe Myc target expression and function in a system where Myc is temporally and physiologically regulated, the transcriptomes and the genome-wide distributions of Myc, RNA polymerase II and chromatin modifications were compared during lymphocyte activation and in ES cells as well. A remarkably simple rule emerged from this quantitative analysis: Myc is not an on-off specifier of gene activity, but is a non-linear amplifier of expression, acting universally at active genes, except for immediate early genes that are strongly induced before Myc. This rule of Myc action explains the vast majority of Myc biology observed in literature. PMID:23021216

  3. C-myc can induce expression of G/sub 0//G/sub 1/ transition genes

    SciTech Connect

    Schweinfest, C.W.; Fujiwara, S.; Lau, L.F.; Papas, T.S.

    1988-08-01

    The human c-myc oncogene was linked to the heat shock-inducible Drosophila hsp70 promoter and used to stably transfect mouse BALB/c 3T3 cells. Heat shock of the transfectants at 42/sup 0/C followed by recovery at 37/sup 0/C resulted in the appearance of the human c-myc protein which was appropriately localized to the nuclear fraction. Two-dimensional analysis of the proteins of density-arrested cells which had been heat shock treated revealed the induction of eight protein species and the repression of five protein species. All of the induced and repressed proteins were nonabundant. cDNA clones corresponding to genes induced during the G/sub 0//G/sub 1/ transition were used as probes to assay for c-myc inducibility of these genes. Two anonymous sequences previously identified as serum inducible (3CH77 and 3CH92) were induced when c-myc was expressed. In response to serum stimulation, 3CH77 and 3CH92 were expressed before c-myc mRNA levels increased. However, in response to specific induction of c-myc by heat shock of serum arrested cells, 3CH77 and 3CH92 mRNA levels increased after the rise in c-myc mRNA. Therefore, the authors hypothesize that abnormal expression of c-myc can induce genes involved in the proliferative response.

  4. Myc versus USF: discrimination at the cad gene is determined by core promoter elements.

    PubMed Central

    Boyd, K E; Farnham, P J

    1997-01-01

    Carbamoyl-phosphate synthase/aspartate carbamoyltransferase/dihydroorotase, which is encoded by the cad gene, is required for the first three rate-limiting steps of de novo pyrimidine biosynthesis. It has been previously demonstrated that cad transcription increases at the G1/S-phase boundary, as quiescent cells reenter the proliferative cell cycle. The growth-responsive element has been mapped to an E box at +65 in the hamster cad promoter. Using an in vivo UV cross-linking and immunoprecipitation assay, we show that Myc, Max, and upstream stimulatory factor (USF) bind to the chromosomal cad promoter. To determine whether binding of Myc-Max or USF is critical for cad growth regulation, we analyzed promoter constructs which contain mutations in the nucleotides flanking the E box. We demonstrate that altering nucleotides which flank the cad E box to sequences which decrease Myc-Max binding in vitro correlates with a loss of cad G1/S-phase transcriptional activation. This result supports the conclusion that binding of Myc-Max, but not USF, is essential for cad regulation. Our investigations demonstrate that the endogenous cad E box can be bound by more than one transcription factor, but growth-induced cad expression is achieved only by Myc. PMID:9111322

  5. Transcription profiling of lung adenocarcinomas of c-myc-transgenic mice: Identification of the c-myc regulatory gene network

    PubMed Central

    Reymann, Susanne; Borlak, Jürgen

    2008-01-01

    Background The transcriptional regulator c-Myc is the most frequently deregulated oncogene in human tumors. Targeted overexpression of this gene in mice results in distinct types of lung adenocarcinomas. By using microarray technology, alterations in the expression of genes were captured based on a female transgenic mouse model in which, indeed, c-Myc overexpression in alveolar epithelium results in the development of bronchiolo-alveolar carcinoma (BAC) and papillary adenocarcinoma (PLAC). In this study, we analyzed exclusively the promoters of induced genes by different in silico methods in order to elucidate the c-Myc transcriptional regulatory network. Results We analyzed the promoters of 361 transcriptionally induced genes with respect to c-Myc binding sites and found 110 putative binding sites in 94 promoters. Furthermore, we analyzed the flanking sequences (+/- 100 bp) around the 110 c-Myc binding sites and found Ap2, Zf5, Zic3, and E2f binding sites to be overrepresented in these regions. Then, we analyzed the promoters of 361 induced genes with respect to binding sites of other transcription factors (TFs) which were upregulated by c-Myc overexpression. We identified at least one binding site of at least one of these TFs in 220 promoters, thus elucidating a potential transcription factor network. The analysis correlated well with the significant overexpression of the TFs Atf2, Foxf1a, Smad4, Sox4, Sp3 and Stat5a. Finally, we analyzed promoters of regulated genes which where apparently not regulated by c-Myc or other c-Myc targeted TFs and identified overrepresented Oct1, Mzf1, Ppargamma, Plzf, Ets, and HmgIY binding sites when compared against control promoter background. Conclusion Our in silico data suggest a model of a transcriptional regulatory network in which different TFs act in concert upon c-Myc overexpression. We determined molecular rules for transcriptional regulation to explain, in part, the carcinogenic effect seen in mice overexpressing the c-Myc

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

    PubMed Central

    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

  7. Repression of SRF target genes is critical for Myc-dependent apoptosis of epithelial cells

    PubMed Central

    Wiese, Katrin E; Haikala, Heidi M; von Eyss, Björn; Wolf, Elmar; Esnault, Cyril; Rosenwald, Andreas; Treisman, Richard; Klefström, Juha; Eilers, Martin

    2015-01-01

    Oncogenic levels of Myc expression sensitize cells to multiple apoptotic stimuli, and this protects long-lived organisms from cancer development. How cells discriminate physiological from supraphysiological levels of Myc is largely unknown. Here, we show that induction of apoptosis by Myc in breast epithelial cells requires association of Myc with Miz1. Gene expression and ChIP-Sequencing experiments show that high levels of Myc invade target sites that lack consensus E-boxes in a complex with Miz1 and repress transcription. Myc/Miz1-repressed genes encode proteins involved in cell adhesion and migration and include several integrins. Promoters of repressed genes are enriched for binding sites of the serum-response factor (SRF). Restoring SRF activity antagonizes Myc repression of SRF target genes, attenuates Myc-induced apoptosis, and reverts a Myc-dependent decrease in Akt phosphorylation and activity, a well-characterized suppressor of Myc-induced apoptosis. We propose that high levels of Myc engage Miz1 in repressive DNA binding complexes and suppress an SRF-dependent transcriptional program that supports survival of epithelial cells. PMID:25896507

  8. IκB kinases increase Myc protein stability and enhance progression of breast cancer cells

    PubMed Central

    2011-01-01

    Background Both IκB kinase (IKK) complex and oncgenic protein Myc play important roles in cancer progression, including cancer cell invasiveness and metastasis. The levels of Myc is regulated by the phosphorylation of Myc at Thr58 and Ser62. Results In this study, we show that the expression of Myc is associated with IKKα and IKKβ in breast cancers and that Myc is an IKKs substrate. Suppression of IKK activity by either chemical inhibitor or transfection of kinase-dead mutants decreases the phosphorylation of Myc at Ser62 and enhances the degradation of Myc. Consequently, these treatments decrease the tumorigenic and invasive ability of breast cancer cells. Furthermore, doxorubicin, a frequently used anticancer drug in breast cancer, activates IKKs and Myc, thereby increasing invasiveness and tumorigenesis of breast carcinoma MCF7 cells. Inhibition of IKKs prevents these doxorubicin-induced effects. Conclusions Our study indicates that IKKs tightly regulate Myc expression through prolonging protein stability, and suggests that IKKs are potentially therapeutic targets and that suppression of IKKs may be used following chemotherapy to reduce the risk of treatment-induced tumor progression. PMID:21575199

  9. The Myc negative autoregulation mechanism requires Myc-Max association and involves the c-myc P2 minimal promoter.

    PubMed Central

    Facchini, L M; Chen, S; Marhin, W W; Lear, J N; Penn, L Z

    1997-01-01

    Increasing evidence supports an important biological role for Myc in the downregulation of specific gene transcription. Recent studies suggest that c-Myc may suppress promoter activity through proteins of the basal transcription machinery. We have previously reported that Myc protein, in combination with additional cellular factors, suppresses transcription initiation from the c-myc promoter. To characterize the cis components of this Myc negative autoregulation pathway, fragments of the human c-myc promoter were inserted upstream of luciferase reporter genes and assayed for responsiveness to inducible MycER activation in Rat-1 fibroblasts. We found four- to fivefold suppression of a c-myc P2 minimal promoter fragment upon induction of wild-type MycER protein activity, while induction of a mutant MycER protein lacking amino acids 106 to 143 required for Myc autosuppression failed to elicit this response. This assay is physiologically significant, as it reflects Myc autosuppression of the endogenous c-myc gene with regard to kinetics, dose dependency, cell type specificity, and c-Myc functional domains. Analysis of mutations within the P2 minimal promoter indicated that the cis components of Myc autosuppression could not be ascribed to any known protein-binding motifs. In addition, to address the trans factors required for Myc negative autoregulation, we expressed MycEG and MaxEG leucine zipper dimerization mutants in Rat-1 cells and found that Myc-Max heterodimerization is obligatory for Myc autosuppression. Two models for the Myc autosuppression mechanism are discussed. PMID:8972190

  10. MYC, Metabolism, and Cancer

    PubMed Central

    Stine, Zachary E.; Walton, Zandra E.; Altman, Brian J.; Hsieh, Annie L.; Dang, Chi V.

    2015-01-01

    Summary The MYC oncogene encodes a transcription factor, MYC, whose broad effects make its precise oncogenic role enigmatically elusive. The evidence to date suggests that MYC triggers selective gene expression amplification to promote cell growth and proliferation. Through its targets, MYC coordinates nutrient acquisition to produce ATP and key cellular building blocks that increase cell mass and trigger DNA replication and cell division. In cancer, genetic and epigenetic derangements silence checkpoints and unleash MYC’s cell growth- and proliferation-promoting metabolic activities. Unbridled growth in response to deregulated MYC expression creates dependence on MYC-driven metabolic pathways, such that reliance on specific metabolic enzymes provides novel targets for cancer therapy. PMID:26382145

  11. Different promoter affinities account for specificity in MYC-dependent gene regulation

    PubMed Central

    Lorenzin, Francesca; Benary, Uwe; Baluapuri, Apoorva; Walz, Susanne; Jung, Lisa Anna; von Eyss, Björn; Kisker, Caroline; Wolf, Jana; Eilers, Martin; Wolf, Elmar

    2016-01-01

    Enhanced expression of the MYC transcription factor is observed in the majority of tumors. Two seemingly conflicting models have been proposed for its function: one proposes that MYC enhances expression of all genes, while the other model suggests gene-specific regulation. Here, we have explored the hypothesis that specific gene expression profiles arise since promoters differ in affinity for MYC and high-affinity promoters are fully occupied by physiological levels of MYC. We determined cellular MYC levels and used RNA- and ChIP-sequencing to correlate promoter occupancy with gene expression at different concentrations of MYC. Mathematical modeling showed that binding affinities for interactions of MYC with DNA and with core promoter-bound factors, such as WDR5, are sufficient to explain promoter occupancies observed in vivo. Importantly, promoter affinity stratifies different biological processes that are regulated by MYC, explaining why tumor-specific MYC levels induce specific gene expression programs and alter defined biological properties of cells. DOI: http://dx.doi.org/10.7554/eLife.15161.001 PMID:27460974

  12. Viral-mediated noisy gene expression reveals biphasic E2f1 response to MYC

    PubMed Central

    Wong, Jeffrey V.; Yao, Guang; Nevins, Joseph R.; You, Lingchong

    2011-01-01

    Gene expression mediated by viral vectors is subject to cell-to-cell variability, which limits the accuracy of gene delivery. When coupled with single-cell measurements, however, such variability provides an efficient means to quantify signaling dynamics in mammalian cells. Here, we illustrate the utility of this approach by mapping the E2f1 response to MYC, serum stimulation, or both. Our results revealed an underappreciated mode of gene regulation: E2f1 expression first increased then decreased as MYC input increased. This biphasic pattern was also reflected in other nodes of the network including the miR-17-92 micro RNA cluster and p19Arf. A mathematical model of the network successfully predicted modulation of the biphasic E2F response by serum and a CDK inhibitor. In addition to demonstrating how noise can be exploited to probe signaling dynamics, our results reveal how coordination of the MYC/RB/E2F pathway enables dynamic discrimination of aberrant and normal levels of growth stimulation. PMID:21292160

  13. Genome-wide mapping of Myc binding and gene regulation in serum-stimulated fibroblasts

    PubMed Central

    Perna, D; Fagà, G; Verrecchia, A; Gorski, M M; Barozzi, I; Narang, V; Khng, J; Lim, K C; Sung, W-K; Sanges, R; Stupka, E; Oskarsson, T; Trumpp, A; Wei, C-L; Müller, H; Amati, B

    2012-01-01

    The transition from quiescence to proliferation is a key regulatory step that can be induced by serum stimulation in cultured fibroblasts. The transcription factor Myc is directly induced by serum mitogens and drives a secondary gene expression program that remains largely unknown. Using mRNA profiling, we identify close to 300 Myc-dependent serum response (MDSR) genes, which are induced by serum in a Myc-dependent manner in mouse fibroblasts. Mapping of genomic Myc-binding sites by ChIP-seq technology revealed that most MDSR genes were directly targeted by Myc, but represented a minor fraction (5.5%) of all Myc-bound promoters (which were 22.4% of all promoters). Other target loci were either induced by serum in a Myc-independent manner, were not significantly regulated or were negatively regulated. MDSR gene products were involved in a variety of processes, including nucleotide biosynthesis, ribosome biogenesis, DNA replication and RNA control. Of the 29 MDSR genes targeted by RNA interference, three showed a requirement for cell-cycle entry upon serum stimulation and 11 for long-term proliferation and/or survival. Hence, proper coordination of key regulatory and biosynthetic pathways following mitogenic stimulation relies upon the concerted regulation of multiple Myc-dependent genes. PMID:21860422

  14. Expression of c-myc gene in human ovary carcinoma cells treated with vanadate

    SciTech Connect

    Itkes, A.V.; Imamova, L.R.; Alexandrova, N.M.; Favorova, O.O.; Kisselev, L.L. )

    1990-05-01

    The widely accepted hypothesis of vanadate action on cells postulates that this ion inhibits protein phosphatase(s) that dephosphorylates protein phosphotyrosine residues. This inhibition causes tyrosine hyperphosphorylation of cell proteins followed by changes in physiological action of phosphoproteins resulting in stimulation of cell proliferation, expression of protooncogenes, and transient cell transformation. The authors have found that treatment of human ovary carcinoma (CaOv) cells with vanadate causes the increase in total protein phosphorylation from 1.5- to 2.0-fold whereas the ratio between phosphoserine, phosphothreonine, and phosphotyrosine content remains unchanged. At the same time, enhancement of c-myc gene expression (not c-fos) was observed. Hence, the increase in the ratio of phosphotyrosine to phosphoserine and phosphothreonine is not an obligatory intermediate stage before vanadate-dependent activation of c-myc expression.

  15. SKP2 Oncogene Is a Direct MYC Target Gene and MYC Down-regulates p27KIP1 through SKP2 in Human Leukemia Cells*

    PubMed Central

    Bretones, Gabriel; Acosta, Juan C.; Caraballo, Juan M.; Ferrándiz, Nuria; Gómez-Casares, M. Teresa; Albajar, Marta; Blanco, Rosa; Ruiz, Paula; Hung, Wen-Chun; Albero, M. Pilar; Perez-Roger, Ignacio; León, Javier

    2011-01-01

    SKP2 is the ubiquitin ligase subunit that targets p27KIP1 (p27) for degradation. SKP2 is induced in the G1-S transit of the cell cycle, is frequently overexpressed in human cancer, and displays transformation activity in experimental models. Here we show that MYC induces SKP2 expression at the mRNA and protein levels in human myeloid leukemia K562 cells with conditional MYC expression. Importantly, in these systems, induction of MYC did not activate cell proliferation, ruling out SKP2 up-regulation as a consequence of cell cycle entry. MYC-dependent SKP2 expression was also detected in other cell types such as lymphoid, fibroblastic, and epithelial cell lines. MYC induced SKP2 mRNA expression in the absence of protein synthesis and activated the SKP2 promoter in luciferase reporter assays. With chromatin immunoprecipitation assays, MYC was detected bound to a region of human SKP2 gene promoter that includes E-boxes. The K562 cell line derives from human chronic myeloid leukemia. In a cohort of chronic myeloid leukemia bone marrow samples, we found a correlation between MYC and SKP2 mRNA levels. Analysis of cancer expression databases also indicated a correlation between MYC and SKP2 expression in lymphoma. Finally, MYC-induced SKP2 expression resulted in a decrease in p27 protein in K562 cells. Moreover, silencing of SKP2 abrogated the MYC-mediated down-regulation of p27. Our data show that SKP2 is a direct MYC target gene and that MYC-mediated SKP2 induction leads to reduced p27 levels. The results suggest the induction of SKP2 oncogene as a new mechanism for MYC-dependent transformation. PMID:21245140

  16. SKP2 oncogene is a direct MYC target gene and MYC down-regulates p27(KIP1) through SKP2 in human leukemia cells.

    PubMed

    Bretones, Gabriel; Acosta, Juan C; Caraballo, Juan M; Ferrándiz, Nuria; Gómez-Casares, M Teresa; Albajar, Marta; Blanco, Rosa; Ruiz, Paula; Hung, Wen-Chun; Albero, M Pilar; Perez-Roger, Ignacio; León, Javier

    2011-03-18

    SKP2 is the ubiquitin ligase subunit that targets p27(KIP1) (p27) for degradation. SKP2 is induced in the G(1)-S transit of the cell cycle, is frequently overexpressed in human cancer, and displays transformation activity in experimental models. Here we show that MYC induces SKP2 expression at the mRNA and protein levels in human myeloid leukemia K562 cells with conditional MYC expression. Importantly, in these systems, induction of MYC did not activate cell proliferation, ruling out SKP2 up-regulation as a consequence of cell cycle entry. MYC-dependent SKP2 expression was also detected in other cell types such as lymphoid, fibroblastic, and epithelial cell lines. MYC induced SKP2 mRNA expression in the absence of protein synthesis and activated the SKP2 promoter in luciferase reporter assays. With chromatin immunoprecipitation assays, MYC was detected bound to a region of human SKP2 gene promoter that includes E-boxes. The K562 cell line derives from human chronic myeloid leukemia. In a cohort of chronic myeloid leukemia bone marrow samples, we found a correlation between MYC and SKP2 mRNA levels. Analysis of cancer expression databases also indicated a correlation between MYC and SKP2 expression in lymphoma. Finally, MYC-induced SKP2 expression resulted in a decrease in p27 protein in K562 cells. Moreover, silencing of SKP2 abrogated the MYC-mediated down-regulation of p27. Our data show that SKP2 is a direct MYC target gene and that MYC-mediated SKP2 induction leads to reduced p27 levels. The results suggest the induction of SKP2 oncogene as a new mechanism for MYC-dependent transformation. PMID:21245140

  17. The transcription factor c-Myc enhances KIR gene transcription through direct binding to an upstream distal promoter element

    PubMed Central

    Cichocki, Frank; Hanson, Rebecca J.; Lenvik, Todd; Pitt, Michelle; McCullar, Valarie; Li, Hongchuan; Anderson, Stephen K.

    2009-01-01

    The killer cell immunoglobulin-like receptor (KIR) repertoire of natural killer (NK) cells determines their ability to detect infected or transformed target cells. Although epigenetic mechanisms play a role in KIR gene expression, work in the mouse suggests that other regulatory elements may be involved at specific stages of NK-cell development. Here we report the effects of the transcription factor c-Myc on KIR expression. c-Myc directly binds to, and promotes transcription from, a distal element identified upstream of most KIR genes. Binding of endogenous c-Myc to the distal promoter element is significantly enhanced upon interleukin-15 (IL-15) stimulation in peripheral blood NK cells and correlates with an increase in KIR transcription. In addition, the overexpression of c-Myc during NK-cell development promotes transcription from the distal promoter element and contributes to the overall transcription of multiple KIR genes. Our data demonstrate the significance of the 5′ promoter element upstream of the conventional KIR promoter region and support a model whereby IL-15 stimulates c-Myc binding at the distal KIR promoter during NK-cell development to promote KIR transcription. This finding provides a direct link between NK-cell activation signals and KIR expression required for acquisition of effector function during NK-cell education. PMID:18987359

  18. SerpinB3 and Yap Interplay Increases Myc Oncogenic Activity

    PubMed Central

    Turato, Cristian; Cannito, Stefania; Simonato, Davide; Villano, Gianmarco; Morello, Elisabetta; Terrin, Liliana; Quarta, Santina; Biasiolo, Alessandra; Ruvoletto, Mariagrazia; Martini, Andrea; Fasolato, Silvano; Zanus, Giacomo; Cillo, Umberto; Gatta, Angelo; Parola, Maurizio; Pontisso, Patrizia

    2015-01-01

    SerpinB3 has been recently described as an early marker of liver carcinogenesis, but the potential mechanistic role of this serpin in tumor development is still poorly understood. Overexpression of Myc often correlates with more aggressive tumour forms, supporting its involvement in carcinogenesis. Yes-associated protein (Yap), the main effector of the Hippo pathway, is a central regulator of proliferation and it has been found up-regulated in hepatocellular carcinomas. The study has been designed to investigate and characterize the interplay and functional modulation of Myc by SerpinB3 in liver cancer. Results from this study indicate that Myc was up-regulated by SerpinB3 through calpain and Hippo-dependent molecular mechanisms in transgenic mice and hepatoma cells overexpressing human SerpinB3, and also in human hepatocellular carcinomas. Human recombinant SerpinB3 was capable to inhibit the activity of Calpain in vitro, likely reducing its ability to cleave Myc in its non oncogenic Myc-nick cytoplasmic form. SerpinB3 indirectly increased the transcription of Myc through the induction of Yap pathway. These findings provide for the first time evidence that SerpinB3 can improve the production of Myc through direct and indirect mechanisms that include the inhibition of generation of its cytoplasmic form and the activation of Yap pathway. PMID:26634820

  19. [PC-1 enhances c-myc gene expression in prostate cancer cells].

    PubMed

    Yu, Lan; Shi, Qing-Guo; Qian, Xiao-Long; Li, Shan-Hu; Wang, Hong-Tao; Wang, Le-Le; Zhou, Jian-Guang

    2010-04-01

    PC-1(Prostate and colon gene 1) gene belongs to TPD52 (Tumor Protein D52) gene family. The expression of PC-1 is found to promote androgen-independent progression. This study was conducted to assess the mechnism of promotion of androgen-independent progression in PC-1 gene. The c-myc gene expression was tested by RT-PCR and Western blotting analyses in the LNCaP-pc-1 and LNCaP-zero cell line. After separation of cytoplasm and nulear proteins of the LNCaP-pc-1 and LNCaP-zero cell line, the beta-catenin protein was detected by Western blotting. C4-2 cell line was used to examine the effects of 10058-F4 on the PC-1 gene expression. The results of RT-PCR and Western blotting indicated that PC-1 enhanced c-myc gene expression in prostate cancer cells, PC-1 was also found to enhance beta-catenin expression in nuclear. Furthermore, a small-molecule c-Myc inhibitor, 10058-F4 represses PC-1 gene expression in C4-2 cell line. Our findings suggest that PC-1 enhances c-myc gene expression in prostate cancer cells through the Wnt/beta-catenin pathway. Meanwhile, c-myc plays a feed-forward role in enhancing PC-1 driven c-myc gene expression, and promotes prostate an-drogen-independent progression. PMID:20423888

  20. Posttranscriptional regulation of cellular gene expression by the c-myc oncogene

    SciTech Connect

    Prendergast, G.C.; Cole, M.D. . Dept. of Biology)

    1989-01-01

    The c-myc oncogene has been implicated in the development of many different cancers, yet the mechanism by which the c-myc protein alters cellular growth control has proven elusive. The authors used a cDNA hybridization difference assay to isolate two genes, mr1 and mr2, that were constitutively expressed (i.e., deregulated) in rodent fibroblast cell lines immortalized by transfection of a viral promoter-linked c-myc gene. Both cDNAs were serum inducible in quiescent G/sub o/ fibroblasts, suggesting that they are functionally related to cellular proliferative processes. Although there were significant differences in cytoplasmic mRNA levels between myc-immortalized and control cells, the rates of transcription and mRNA turnover of both genes were similar, suggesting that c-myc regulates mr1 and mr2 expression by some nuclear posttranscriptional mechanism. Their results provide evidence that c-myc can rapidly modulate cellular gene expression and suggest that c-myc may function in gene regulation at the level of RNA export, splicing, or nuclear RNA turnover.

  1. Pin1 Regulates the Dynamics of c-Myc DNA Binding To Facilitate Target Gene Regulation and Oncogenesis

    PubMed Central

    Farrell, Amy S.; Pelz, Carl; Wang, Xiaoyan; Daniel, Colin J.; Wang, Zhiping; Su, Yulong; Janghorban, Mahnaz; Zhang, Xiaoli; Morgan, Charlie; Impey, Soren

    2013-01-01

    The Myc oncoprotein is considered a master regulator of gene transcription by virtue of its ability to modulate the expression of a large percentage of all genes. However, mechanisms that direct Myc's recruitment to DNA and target gene selection to elicit specific cellular functions have not been well elucidated. Here, we report that the Pin1 prolyl isomerase enhances recruitment of serine 62-phosphorylated Myc and its coactivators to select promoters during gene activation, followed by promoting Myc's release associated with its degradation. This facilitates Myc's activation of genes involved in cell growth and metabolism, resulting in enhanced proproliferative activity, even while controlling Myc levels. In cancer cells with impaired Myc degradation, Pin1 still enhances Myc DNA binding, although it no longer facilitates Myc degradation. Thus, we find that Pin1 and Myc are cooverexpressed in cancer, and this drives a gene expression pattern that we show is enriched in poor-outcome breast cancer subtypes. This study provides new insight into mechanisms regulating Myc DNA binding and oncogenic activity, it reveals a novel role for Pin1 in the regulation of transcription factors, and it elucidates a mechanism that can contribute to oncogenic cooperation between Pin1 and Myc. PMID:23716601

  2. Evidence that the familial adenomatous polyposis gene is involved in a subset of colon cancers with a complementable defect in c-myc regulation

    SciTech Connect

    Erisman, M.D.; Scott, J.K.; Astrin, S.M. )

    1989-06-01

    Human colorectal carcinomas frequently express elevated levels of c-myc mRNA in the absence of a gross genetic change at the c-myc locus. To test the hypothesis that these tumors are defective in a gene function necessary for the regulation of c-myc expression, the authors fused an osteosarcoma cell line that exhibits normal c-myc regulation with two colon carcinoma cell lines that express deregulated levels of c-myc mRNA. Since rates of c-myc mRNA turnover in the colon carcinoma cells were found to be comparable to those in normal cells, increased message stability cannot account for the increased steady-state levels of transcripts. These finding suggest that loss of function of a trans-acting regulator is responsible for the deregulation of c-myc expression in a major fraction of colorectal carcinomas. Analysis of restriction fragment length polymorphisms in tumor/normal tissue pairs from patients with primary colorectal lesions indicated that deregulation of c-myc expression in the tumors is correlated with frequent loss of alleles of syntenic markers on chromosome 5q. Chromosome 5q is the region known to contain the gene for familial adenomatous polyposis, an inherited predisposition to colon cancer. These findings, together with the arlier finding that the colonic distribution of tumors exhibiting deregulated c-myc expression is similar to that reported for familial polyposis, provide evidence that loss of function of the familial adenomatous polyposis gene is involved in a subset of colorectal cancers in which c-myc expression is deregulated.

  3. An integrated database of genes responsive to the Myc oncogenic transcription factor: identification of direct genomic targets

    PubMed Central

    Zeller, Karen I; Jegga, Anil G; Aronow, Bruce J; O'Donnell, Kathryn A; Dang, Chi V

    2003-01-01

    We report a database of genes responsive to the Myc oncogenic transcription factor. The database Myc Target Gene prioritizes candidate target genes according to experimental evidence and clusters responsive genes into functional groups. We coupled the prioritization of target genes with phylogenetic sequence comparisons to predict c-Myc target binding sites, which are in turn validated by chromatin immunoprecipitation assays. This database is essential for the understanding of the genetic regulatory networks underlying the genesis of cancers. PMID:14519204

  4. MYC and Breast Cancer

    PubMed Central

    Xu, Jinhua; Chen, Yinghua; Olopade, Olufunmilayo I.

    2010-01-01

    MYC is a key regulator of cell growth, proliferation, metabolism, differentiation, and apoptosis. MYC deregulation contributes to breast cancer development and progression and is associated with poor outcomes. Multiple mechanisms are involved in MYC deregulation in breast cancer, including gene amplification, transcriptional regulation, and mRNA and protein stabilization, which correlate with loss of tumor suppressors and activation of oncogenic pathways. The heterogeneity in breast cancer is increasingly recognized. Breast cancer has been classified into 5 or more subtypes based on gene expression profiles, and each subtype has distinct biological features and clinical outcomes. Among these subtypes, basal-like tumor is associated with a poor prognosis and has a lack of therapeutic targets. MYC is overexpressed in the basal-like subtype and may serve as a target for this aggressive subtype of breast cancer. Tumor suppressor BRCA1 inhibits MYC’s transcriptional and transforming activity. Loss of BRCA1 with MYC overexpression leads to the development of breast cancer—especially, basal-like breast cancer. As a downstream effector of estrogen receptor and epidermal growth factor receptor family pathways, MYC may contribute to resistance to adjuvant therapy. Targeting MYC-regulated pathways in combination with inhibitors of other oncogenic pathways may provide a promising therapeutic strategy for breast cancer, the basal-like subtype in particular. PMID:21779462

  5. Characterization of a new melanocyte-specific gene (QNR-71) expressed in v-myc-transformed quail neuroretina.

    PubMed Central

    Turque, N; Denhez, F; Martin, P; Planque, N; Bailly, M; Bègue, A; Stéhelin, D; Saule, S

    1996-01-01

    Quail neuroretina cells (QNR) infected with the v-myc-expressing retrovirus MC29 become pigmented after several passages in vitro. After differential screening of a cDNA library constructed from these cells, we have isolated a cDNA clone (QNR-71) which identifies an RNA expressed only in the pigmented layer of the retina and in the epidermis. This gene can also be induced in other cell types transformed by MC29, suggesting that QNR-71 may be regulated by the v-myc protein. Sequence analysis showed that the QNR-71 cDNA exhibits stretches of homologies with melanosomal proteins encoding genes. From bacterially expressed QNR-71 peptides we obtained rabbit antisera able to specifically recognize two proteins of 95 and 100 kDa in pigmented retinal cells, but not in the neuroretina. To study the regulation of QNR-71, we used promoter fragments linked to the CAT reporter gene, in transient co-expression assay. We observed an increase in CAT expression with a c-MYC and microphtalmia (mi) expression vectors. Both MYC and mi activate the QNR-71 promoter through direct binding to a CATGTG site present in the promoter fragment. Images PMID:8670835

  6. Regulation of MYC gene expression by aberrant Wnt/β-catenin signaling in colorectal cancer

    PubMed Central

    Rennoll, Sherri; Yochum, Gregory

    2015-01-01

    The Wnt/β-catenin signaling pathway controls intestinal homeostasis and mutations in components of this pathway are prevalent in human colorectal cancers (CRCs). These mutations lead to inappropriate expression of genes controlled by Wnt responsive DNA elements (WREs). T-cell factor/Lymphoid enhancer factor transcription factors bind WREs and recruit the β-catenin transcriptional co-activator to activate target gene expression. Deregulated expression of the c-MYC proto-oncogene (MYC) by aberrant Wnt/β-catenin signaling drives colorectal carcinogenesis. In this review, we discuss the current literature pertaining to the identification and characterization of WREs that control oncogenic MYC expression in CRCs. A common theme has emerged whereby these WREs often map distally to the MYC genomic locus and control MYC gene expression through long-range chromatin loops with the MYC proximal promoter. We propose that by determining which of these WREs is critical for CRC pathogenesis, novel strategies can be developed to treat individuals suffering from this disease. PMID:26629312

  7. N-Myc regulates expression of pluripotency genes in neuroblastoma including lif, klf2, klf4, and lin28b.

    PubMed

    Cotterman, Rebecca; Knoepfler, Paul S

    2009-01-01

    myc genes are best known for causing tumors when overexpressed, but recent studies suggest endogenous myc regulates pluripotency and self-renewal of stem cells. For example, N-myc is associated with a number of tumors including neuroblastoma, but also plays a central role in the function of normal neural stem and precursor cells (NSC). Both c- and N-myc also enhance the production of induced pluripotent stem cells (iPSC) and are linked to neural tumor stem cells. The mechanisms by which myc regulates normal and neoplastic stem-related functions remain largely open questions. Here from a global, unbiased search for N-Myc bound genes using ChIP-chip assays in neuroblastoma, we found lif as a putative N-Myc bound gene with a number of strong N-Myc binding peaks in the promoter region enriched for E-boxes. Amongst putative N-Myc target genes in expression microarray studies in neuroblastoma we also found lif and three additional important embryonic stem cell (ESC)-related factors that are linked to production of iPSC: klf2, klf4, and lin28b. To examine the regulation of these genes by N-Myc, we measured their expression using neuroblastoma cells that contain a Tet-regulatable N-myc transgene (TET21N) as well as NSC with a nestin-cre driven N-myc knockout. N-myc levels closely correlated with the expression of all of these genes in neuroblastoma and all but lif in NSC. Direct ChIP assays also indicate that N-Myc directly binds the lif promoter. N-Myc regulates trimethylation of lysine 4 of histone H3 in the promoter of lif and possibly in the promoters of several other stem-related genes. Together these findings indicate that N-Myc regulates overlapping stem-related gene expression programs in neuroblastoma and NSC, supporting a novel model by which amplification of the N-myc gene may drive formation of neuroblastoma. They also suggest mechanisms by which Myc proteins more generally contribute to maintenance of pluripotency and self-renewal of ESC as well as to i

  8. Targeted repression of AXIN2 and MYC gene expression using designer TALEs

    SciTech Connect

    Rennoll, Sherri A.; Scott, Samantha A.; Yochum, Gregory S.

    2014-04-18

    Highlights: • We designed TALE–SID fusion proteins to target AXIN2 and MYC. • TALE–SIDs bound the chromosomal AXIN2 and MYC genes and repressed their expression. • TALE–SIDs repress β-catenin{sup S45F}-dependent AXIN2 and MYC transcription. - Abstract: Designer TALEs (dTALEs) are chimeric transcription factors that can be engineered to regulate gene expression in mammalian cells. Whether dTALEs can block gene transcription downstream of signal transduction cascades, however, has yet to be fully explored. Here we tested whether dTALEs can be used to target genes whose expression is controlled by Wnt/β-catenin signaling. TALE DNA binding domains were engineered to recognize sequences adjacent to Wnt responsive enhancer elements (WREs) that control expression of axis inhibition protein 2 (AXIN2) and c-MYC (MYC). These custom DNA binding domains were linked to the mSin3A interaction domain (SID) to generate TALE–SID chimeric repressors. The TALE–SIDs repressed luciferase reporter activity, bound their genomic target sites, and repressed AXIN2 and MYC expression in HEK293 cells. We generated a novel HEK293 cell line to determine whether the TALE–SIDs could function downstream of oncogenic Wnt/β-catenin signaling. Treating these cells with doxycycline and tamoxifen stimulates nuclear accumulation of a stabilized form of β-catenin found in a subset of colorectal cancers. The TALE–SIDs repressed AXIN2 and MYC expression in these cells, which suggests that dTALEs could offer an effective therapeutic strategy for the treatment of colorectal cancer.

  9. Transcriptional control of DNA replication licensing by Myc

    NASA Astrophysics Data System (ADS)

    Valovka, Taras; Schönfeld, Manuela; Raffeiner, Philipp; Breuker, Kathrin; Dunzendorfer-Matt, Theresia; Hartl, Markus; Bister, Klaus

    2013-12-01

    The c-myc protooncogene encodes the Myc transcription factor, a global regulator of fundamental cellular processes. Deregulation of c-myc leads to tumorigenesis, and c-myc is an important driver in human cancer. Myc and its dimerization partner Max are bHLH-Zip DNA binding proteins involved in transcriptional regulation of target genes. Non-transcriptional functions have also been attributed to the Myc protein, notably direct interaction with the pre-replicative complex (pre-RC) controlling the initiation of DNA replication. A key component of the pre-RC is the Cdt1 protein, an essential factor in origin licensing. Here we present data suggesting that the CDT1 gene is a transcriptional target of the Myc-Max complex. Expression of the CDT1 gene in v-myc-transformed cells directly correlates with myc expression. Also, human tumor cells with elevated c-myc expression display increased CDT1 expression. Occupation of the CDT1 promoter by Myc-Max is demonstrated by chromatin immunoprecipitation, and transactivation by Myc-Max is shown in reporter assays. Ectopic expression of CDT1 leads to cell transformation. Our results provide a possible direct mechanistic link of Myc's canonical function as a transcription factor to DNA replication. Furthermore, we suggest that aberrant transcriptional activation of CDT1 by deregulated myc alleles contributes to the genomic instabilities observed in tumor cells.

  10. Cytotoxicity and altered c-myc gene expression by medical polyacrylamide hydrogel.

    PubMed

    Xi, T F; Fan, C X; Feng, X M; Wan, Z Y; Wang, C R; Chou, L L

    2006-08-01

    Medical Polyacrylamide Hydrogel (PAMG)has been used in plastic and aesthetic surgery for years. However, its safety is still in doubt in many countries. In the current research, first an approach, using high performance liquid chromatography (HPLC), to determine the amount of residual acrylamide monomer (AM) in the PAMG was presented. Then the cytotoxicity of PAMG was investigated using cell counting and methyl thiazolyl tetrazolium (MTT) assay. To explore the mechanism of this toxicity, normal human fibroblasts cultured in medium extracts were analyzed. Membrane changes and other related parameters were investigated using flow cytometry (FCM). Real time fluorescent polymerase chain reaction (real time PCR) was also introduced to determine the biological response of the fibroblasts. During this process, three representative genes (p53, beta-actin, and c-myc, which are tumor suppressor genes, housekeeping genes, and proto-oncogenes respectively) were selected for examination. Results indicated that a method based on HPLC is practical and simple for determining AM in PAMG. The detection limits can reach the desired ppb level, and so it can fully meet the requirements of the studies of PAMG. Polyacylamide Hydrogel inhibits the growth of human fibroblasts and may cause the apoptosis of human fibroblasts. Moreover, it can alter physical parameters such as the size and the granularity of these cells. Furthermore, these three genes have a relatively typical amplification plot and highly related, wide-range standard curves, and so this reaction system is definitely suitable for the semiquantification of these genes. PAMG induces the increase of the message ribonucleic acid (mRNA) expression of c-myc, while the p53 and beta-actin remain even. This change is not related to the concentration of AM in the gel and may be incited by other components in the extract of PMAG. PMID:16637045

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

    SciTech Connect

    Harnicarova, Andrea; Kozubek, Stanislav . E-mail: kozubek@ibp.cz; Pachernik, Jiri; Krejci, Jana; Bartova, 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.

  12. Aberrant immunoglobulin and c-myc gene rearrangements in patients with nonmalignant monoclonal cryoglobulinemia

    SciTech Connect

    Perl, A.; Wang, N.; Williams, J.M.; Hunt, M.J.; Rosenfeld, S.I.; Condemi, J.J.; Packman, C.H.; Abraham, G.N.

    1987-11-15

    The status of the immunoglobulin (Ig) genes was investigated in patients with idiopathic nonmalignant monoclonal IgG cryoglobulinemia (NCG). In NCG, monoclonal antibodies are synthesized at an accelerated rate by nonmalignant B lymphocytes. In order to determine whether this high production rate is related to a clonal B cell expansion, the rearrangement of the Ig genes was investigated by Southern blot analysis of genomic, /sup 32/P-labelled, DNA extracted from the peripheral blood lymphocytes of four NCG patients. In three of four (VI, BR, and CH) clonal expansion of B cells was detected using probes specific for the genes. BamHI digestion of DNA from VI and BR produced three rearranged fragments which cohybridized with two of the probes. This finding suggested the presence of additional nonsecretory B cell clones and/or disruption of the gene segments spanned by and detected with the probes. In addition, the possibility of aberrant gene rearrangements was supported by noting the alteration of the c-myc gene locus in genomic DNA from peripheral blood leukocytes of VI and CH. Northern blot analysis of RNA isolated from peripheral blood B cells of VI and CH demonstrated aberrant transcripts of the c-myc gene, showing an active role of the altered c-myc locus. Detection of c-myc rearrangement in NCG patients clearly shows that this event may not be a final step in malignant B cell transformation.

  13. Gene expression profiling of MYC-driven tumor signatures in porcine liver stem cells by transcriptome sequencing

    Technology Transfer Automated Retrieval System (TEKTRAN)

    It is now well-established that cancer stem cells (CSCs) drive tumor growth and that the cancer gene, c-Myc, plays a critical role in converting cells to CSCs. However, little is known about the genes that are induced and regulated by c-Myc to generate tumors, and, in particular, tumors of the live...

  14. Two N-myc polypeptides with distinct amino termini encoded by the second and third exons of the gene.

    PubMed Central

    Mäkelä, T P; Saksela, K; Alitalo, K

    1989-01-01

    The N-myc and c-myc genes encode closely related nuclear phosphoproteins. We found that the N-myc protein from human tumor cell lines appears as four closely migrating polypeptide bands (p58 to p64) in sodium dodecyl sulfate-polyacrylamide gels. This and the recent finding that the c-myc protein is synthesized from two translational initiation sites located in the first and second exons of the gene (S. R. Hann, M. W. King, D. L. Bentley, C. W. Anderson, and R. N. Eisenman, Cell 52:185-195, 1988) prompted us to study the molecular basis of the N-myc protein heterogeneity. Dephosphorylation by alkaline phosphatase reduced the four polypeptide bands to a doublet with an electrophoretic mobility corresponding to the two faster-migrating N-myc polypeptides (p58 and p60). When expressed transiently in COS cells, an N-myc deletion construct lacking the first exon produced polypeptides similar to the wild-type N-myc protein, indicating that the first exon of the N-myc gene is noncoding. Furthermore, mutants deleted of up to two thirds of C-terminal coding domains still retained the capacity to produce a doublet of polypeptides, suggesting distinct amino termini for the two N-myc polypeptides. The amino-terminal primary structure of the N-myc protein was studied by site-specific point mutagenesis of the 5' end of the long open reading frame and by N-terminal radiosequencing of the two polypeptides. Our results show that the N-myc polypeptides are initiated from two alternative in-phase AUG codons located 24 base pairs apart at the 5' end of the second exon. Both of these polypeptides are phosphorylated and localized to the nucleus even when expressed separately. Interestingly, DNA rearrangements activating the c-myc gene are often found in the 1.7-kilobase-pair region between the two c-myc translational initiation sites and correlate with the loss of the longer c-myc polypeptide. Thus the close spacing of the two N-myc initiation codons could explain the relative resistance

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

    PubMed Central

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

    2013-01-01

    The drivers of abnormal DNA methylation in human cancers include widespread aberrant splicing of the DNMT3B gene, producing abnormal transcripts that encode truncated proteins that may act as dominant negative isoforms. To test whether reduced Dnmt3b dosage can alter tumorigenesis, we bred Dnmt3b+/− mice to Eµ-Myc mice, a mouse model susceptible to B-cell lymphomas. Eµ-Myc/Dnmt3b+/− mice showed a dramatic acceleration of lymphomagenesis, greater even than that observed in Eµ-Myc mice that express a truncated DNMT3B isoform found in human tumors, DNMT3B7. This finding indicates that Dnmt3b can act as a haploinsufficient tumor suppressor gene. Although reduction in both Dnmt3b dosage and expression of DNMT3B7 within the Eµ-Myc system had similar effects on tumorigenesis and DNA hypermethylation, different molecular mechanisms appear to underlie these changes. This study offers insight into how de novo DNA methyltransferases function as tumor suppressors and the sensitivity of Myc-induced lymphomas to DNA methylation. PMID:23315164

  16. Liver tumor formation by a mutant retinoblastoma protein in the transgenic mice is caused by an upregulation of c-Myc target genes

    SciTech Connect

    Wang, Bo; Hikosaka, Keisuke; Sultana, Nishat; Sharkar, Mohammad Tofael Kabir; Noritake, Hidenao; Kimura, Wataru; Wu, Yi-Xin; Kobayashi, Yoshimasa; Uezato, Tadayoshi; Miura, Naoyuki

    2012-01-06

    Highlights: Black-Right-Pointing-Pointer Fifty percent of the mutant Rb transgenic mice produced liver tumors. Black-Right-Pointing-Pointer In the tumor, Foxm1, Skp2, Bmi1 and AP-1 mRNAs were up-regulated. Black-Right-Pointing-Pointer No increase in expression of the Myc-target genes was observed in the non-tumorous liver. Black-Right-Pointing-Pointer Tumor formation depends on up-regulation of the Myc-target genes. -- Abstract: The retinoblastoma (Rb) tumor suppressor encodes a nuclear phosphoprotein that regulates cellular proliferation, apoptosis and differentiation. In order to adapt itself to these biological functions, Rb is subjected to modification cycle, phosphorylation and dephosphorylation. To directly determine the effect of phosphorylation-resistant Rb on liver development and function, we generated transgenic mice expressing phosphorylation-resistant human mutant Rb (mt-Rb) under the control of the rat hepatocyte nuclear factor-1 gene promoter/enhancer. Expression of mt-Rb in the liver resulted in macroscopic neoplastic nodules (adenomas) with {approx}50% incidence within 15 months old. Interestingly, quantitative reverse transcriptase-PCR analysis showed that c-Myc was up-regulated in the liver of mt-Rb transgenic mice irrespective of having tumor tissues or no tumor. In tumor tissues, several c-Myc target genes, Foxm1, c-Jun, c-Fos, Bmi1 and Skp2, were also up-regulated dramatically. We determined whether mt-Rb activated the Myc promoter in the HTP9 cells and demonstrated that mt-Rb acted as an inhibitor of wild-type Rb-induced repression on the Myc promoter. Our results suggest that continued upregulation of c-Myc target genes promotes the liver tumor formation after about 1 year of age.

  17. C-Myc Induced Compensated Cardiac Hypertrophy Increases Free Fatty Acid Utilization for the Citric Acid Cycle

    SciTech Connect

    Olson, Aaron; Ledee, Dolena; Iwamoto, Kate; Kajimoto, Masaki; O'Kelly-Priddy, Colleen M.; Isern, Nancy G.; Portman, Michael A.

    2013-02-01

    The protooncogene C-Myc (Myc) regulates cardiac hypertrophy. Myc promotes compensated cardiac function, suggesting that the operative mechanisms differ from those leading to heart failure. Myc regulation of substrate metabolism is a reasonable target, as Myc alters metabolism in other tissues. We hypothesize that Myc-induced shifts in substrate utilization signal and promote compensated hypertrophy. We used cardiac specific Myc-inducible C57/BL6 male mice between 4-6 months old that develop hypertrophy with tamoxifen (tam). Isolated working hearts and 13Carbon (13C )-NMR were used to measure function and fractional contributions (Fc) to the citric acid cycle by using perfusate containing 13C-labeled free fatty acids, acetoacetate, lactate, unlabeled glucose and insulin. Studies were performed at pre-hypertrophy (3-days tam, 3dMyc), established hypertrophy (7-days tam, 7dMyc) or vehicle control (cont). Non-transgenic siblings (NTG) received 7-days tam or vehicle to assess drug effect. Hypertrophy was confirmed by echocardiograms and heart weights. Western blots were performed on key metabolic enzymes. Hypertrophy occurred in 7dMyc only. Cardiac function did not differ between groups. Tam alone did not affect substrate contribution in NTG. Substrate utilization was not significantly altered in 3dMyc versus cont. The free fatty acid FC was significantly greater in 7dMyc vs cont with decreased unlabeled Fc, which is predominately exogenous glucose. Free fatty acid flux to the citric acid cycle increased while lactate flux was diminished in 7dMyc compared to cont. Total protein levels of a panel of key metabolic enzymes were unchanged; however total protein O-GlcNAcylation was increased in 7dMyc. Substrate utilization changes did not precede hypertrophy; therefore they are not the primary signal for cardiac growth in this model. Free fatty acid utilization and oxidation increase at established hypertrophy. Understanding the mechanisms whereby this change maintained

  18. Resistance to anticancer drugs in NIH3T3 cells transfected with c-myc and/or c-H-ras genes.

    PubMed Central

    Niimi, S.; Nakagawa, K.; Yokota, J.; Tsunokawa, Y.; Nishio, K.; Terashima, Y.; Shibuya, M.; Terada, M.; Saijo, N.

    1991-01-01

    NIH3T3 cells transfected with c-H-ras and/or c-myc genes were examined for differences in drug sensitivity. The five transfectants used were N8, NIH3T3-nm-1, pT22-3-nm-2, pP1-4 and pT22-3. They were transfected with pKOneo alone, pKOneo and c-myc, pKOneo and c-myc plus activated c-H-ras, normal c-H-ras and activated c-H-ras genes, respectively. The IC50s of cisplatin, 4-hydroperoxycyclophosphamide, adriamycin, melphalan, and CPT-11 were significantly higher for NIH3T3-nm-1 abd pT22-3-nm-2 than for the parental NIH3T3 and N8 cells. Transfection with normal and activated C-H-ras oncogenes only led to increases in the IC50s of alkylating agents. There was no significant difference between the IC50s of N8 and those of NIH3T3 parental cells to any of these anticancer agents. These results strongly suggest that the expression of the c-myc gene plays a role in the acquisition of drug resistance. The c-myc gene may therefore provide us with an important clue in determining the mechanism of drug resistance. Images Figure 1 Figure 2 Figure 3 PMID:1997100

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

    SciTech Connect

    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.

  20. Analysis of the tumorigenic potential of common marmoset lymphoblastoid cells expressing a constitutively activated c-myc gene.

    PubMed Central

    Hotchin, N. A.; Wedderburn, N.; Roberts, I.; Thomas, J. A.; Bungey, J. A.; Naylor, B.; Crawford, D. H.

    1993-01-01

    The respective roles of Epstein-Barr virus (EBV) and c-myc in the pathogenesis of endemic Burkitt's lymphoma (BL) are unclear. In order to help resolve the question whether constitutive expression of the c-myc gene in an EBV-immortalised B cell is sufficient to induce a tumorigenic phenotype, B cells from a common marmoset (Callithrix jacchus) were immortalised with EBV, transfected with a constitutively activated c-myc gene and inoculated into the host animals. Despite the cell line transfected with c-myc displaying enhanced growth characteristics, in vitro and in vivo experiments demonstrated that this was not sufficient to induce a tumorigenic phenotype. This supports our previous findings with EBV-immortalised human B cells transfected with an activated c-myc gene (Hotchin et al., 1990). Images Figure 1 Figure 2 Figure 4 PMID:8388232

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

    PubMed

    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. PMID:27002159

  2. Myc-Max heterodimers activate a DEAD box gene and interact with multiple E box-related sites in vivo.

    PubMed Central

    Grandori, C; Mac, J; Siëbelt, F; Ayer, D E; Eisenman, R N

    1996-01-01

    The c-Myc protein is involved in cell proliferation, differentiation and apoptosis though heterodimerization with Max to form a transcriptionally active sequence-specific DNA binding complex. By means of sequential immunoprecipitation of chromatin using anti-Max and anti-Myc antibodies, we have identified a Myc-regulated gene and genomic sites occupied by Myc-Max in vivo. Four of 27 sites recovered by this procedure corresponded to the highest affinity 'canonical' CACGTG sequence. However, the most common in vivo binding sites belonged to the group of 'non-canonical' E box-related binding sites previously identified by in vitro selection. Several of the genomic fragments isolated contained transcribed sequences, including one, MrDb, encoding an evolutionarily conserved RNA helicase of the DEAD box family. The corresponding mRNA was induced following activation of a Myc-estrogen receptor fusion protein (Myc-ER) in the presence of a protein synthesis inhibitor, consistent with this helicase gene being a direct target of Myc-Max. In addition, as for c-Myc, the expression of MrDb is induced upon proliferative stimulation of primary human fibroblasts as well as B cells and down-regulated during terminal differentiation of HL60 leukemia cells. Our results indicate that Myc-Max heterodimers interact in vivo with a specific set of E box-related DNA sequences and that Myc is likely to activate multiple target genes including a highly conserved DEAD box protein. Therefore, Myc may exert its effects on cell behavior through proteins that affect RNA structure and metabolism. Images PMID:8861962

  3. A transgenic zebrafish liver tumor model with inducible Myc expression reveals conserved Myc signatures with mammalian liver tumors

    PubMed Central

    Li, Zhen; Zheng, Weiling; Wang, Zhengyuan; Zeng, Zhiqiang; Zhan, Huiqing; Li, Caixia; Zhou, Li; Yan, Chuan; Spitsbergen, Jan M.; Gong, Zhiyuan

    2013-01-01

    SUMMARY Myc is a pleiotropic transcription factor that is involved in many cellular activities relevant to carcinogenesis, including hepatocarcinogenesis. The zebrafish has been increasingly used to model human diseases and it is particularly valuable in helping to identify common and conserved molecular mechanisms in vertebrates. Here we generated a liver tumor model in transgenic zebrafish by liver-specific expression of mouse Myc using a Tet-On system. Dosage-dependent induction of Myc expression specifically in the liver was observed in our Myc transgenic zebrafish, TO(Myc), and the elevated Myc expression caused liver hyperplasia, which progressed to hepatocellular adenoma and carcinoma with prolonged induction. Next generation sequencing-based transcriptomic analyses indicated that ribosome proteins were overwhelmingly upregulated in the Myc-induced liver tumors. Cross-species analyses showed that the zebrafish Myc model correlated well with Myc transgenic mouse models for liver cancers. The Myc-induced zebrafish liver tumors also possessed molecular signatures highly similar to human those of hepatocellular carcinoma. Finally, we found that a small Myc target gene set of 16 genes could be used to identify liver tumors due to Myc upregulation. Thus, our zebrafish model demonstrated the conserved role of Myc in promoting hepatocarcinogenesis in all vertebrate species. PMID:23038063

  4. Role of arabidopsis MYC and MYB homologs in drought- and abscisic acid-regulated gene expression.

    PubMed Central

    Abe, H; Yamaguchi-Shinozaki, K; Urao, T; Iwasaki, T; Hosokawa, D; Shinozaki, K

    1997-01-01

    In Arabidopsis, the induction of a dehydration-responsive gene, rd22, is mediated by abscisic acid (ABA) and requires protein biosynthesis for ABA-dependent gene expression. Previous experiments established that a 67-bp DNA fragment of the rd22 promoter is sufficient for dehydration- and ABA-induced gene expression and that this DNA fragment contains two closely located putative recognition sites for the basic helix-loop-helix protein MYC and one putative recognition site for MYB. We have carefully analyzed the 67-bp region of the rd22 promoter in transgenic tobacco plants and found that both the first MYC site and the MYB recognition site function as cis-acting elements in the dehydration-induced expression of the rd22 gene. A cDNA encoding a MYC-related DNA binding protein was isolated by DNA-ligand binding screening, using the 67-bp region as a probe, and designated rd22BP1. The rd22BP1 cDNA encodes a 68-kD protein that has a typical DNA binding domain of a basic region helix-loop-helix leucine zipper motif in MYC-related transcription factors. The rd22BP1 protein binds specifically to the first MYC recognition site in the 67-bp fragment. RNA gel blot analysis revealed that transcription of the rd22BP1 gene is induced by dehydration stress and ABA treatment, and its induction precedes that of rd22. We have reported a drought- and ABA-inducible gene that encodes the MYB-related protein ATMYB2. In a transient transactivation experiment using Arabidopsis leaf protoplasts, we demonstrated that both the rd22BP1 and ATMYB2 proteins activate transcription of the rd22 promoter fused to the beta-glucuronidase reporter gene. These results indicate that both the rd22BP1 (MYC) and ATMYB2 (MYB) proteins function as transcriptional activators in the dehydration- and ABA-inducible expression of the rd22 gene. PMID:9368419

  5. Availability of subfertile transgenic rats expressing the c-myc gene as recipients for spermatogonial transplantation.

    PubMed

    Hirabayashi, Masumi; Yoshizawa, Yusuke; Kato, Megumi; Tsuchiya, Takashi; Nagao, Shizuko; Hochi, Shinichi

    2009-02-01

    The spermatogonial transplantation system was applied to evaluate stem cell kinetics and niche quality and to produce gene-modified animals using the stem cells after homologous recombination-based selection. This study was designed to determine whether the transplanted spermatogonia were able to proliferate and differentiate in male rats expressing the c-myc transgene under control of the human metallothionein IIA promoter (MT-myc Tg rats). Donor testicular cells were prepared from heterozygous chicken beta actin (CAG)/enhanced green fluorescent protein (EGFP)-transgenic rats (EGFP Tg rats) during the second week after birth and injected into the seminiferous tubules of the MT-myc Tg rats (line-A and -B; both subfertile) or rats pretreated with busulfan to remove endogenous spermatogonia. Three to four months after transplantation, cell colonies with EGFP fluorescence were detected in 36% (4/11), 40% (8/20), and 71% (5/7) of the transplanted testes in line-A MT-myc Tg rats, line-B MT-myc Tg rats, and busulfan-treated rats, respectively. No EGFP-positive colonies were detected when wild-type male rats were used as recipients (0/7; testis-basis). The histopathological and immunofluorescent examination of the serial sections from the transplanted testes showed normal spermatogenesis of the donor spermatogonia, but atrophy of the recipient seminiferous tubules. Microinsemination with round spermatids and mature spermatozoa derived from EGFP-positive testes in line-A rats resulted 26% (10/39 transferred) and 23% (11/48 transferred) full-term offspring, respectively. Thus, the MT-myc Tg male rats were suitable as potent recipients for spermatogonial transplantation without any chemical pretreatment to remove the endogenous spermatogonia. PMID:18830680

  6. MYC/MIZ1-dependent gene repression inversely coordinates the circadian clock with cell cycle and proliferation

    PubMed Central

    Shostak, Anton; Ruppert, Bianca; Ha, Nati; Bruns, Philipp; Toprak, Umut H.; Lawerenz, Chris; Lichter, Peter; Radlwimmer, Bernhard; Eils, Jürgen; Brors, Benedikt; Radomski, Sylwester; Scholz, Ingrid; Richter, Gesine; Siebert, Reiner; Wagner, Susanne; Haake, Andrea; Richter, Julia; Aukema, Sietse; Ammerpohl, Ole; Lopez, Christina; Nagel, Inga; Vater, Inga; Wagner, Rabea; Borst, Christoph; Haas, Siegfried; Rohde, Marius; Burkhardt, Birgit; Lisfeld, Jasmin; Claviez, Alexander; Dreyling, Martin; Eberth, Sonja; Trümper, Lorenz; Kube, Dieter; Stadler, Christina; Einsele, Hermann; Frickhofen, Norbert; Hansmann, Martin-Leo; Karsch, Dennis; Kneba, Michael; Mantovani-Löffler, Luisa; Staib, Peter; Stilgenbauer, Stephan; Ott, German; Küppers, Ralf; Weniger, Marc; Hummel, Michael; Lenze, Dido; Szczepanowski, Monika; Klapper, Wolfram; Kostezka, Ulrike; Möller, Peter; Rosenwald, Andreas; Leich, Ellen; Pischimariov, Jordan; Binder, Vera; Borkhardt, Arndt; Hezaveh, Kebria; Hoell, Jessica; Rosenstiel, Philip; Schilhabel, Markus; Schreiber, Stefan; Bernhart, Stephan H.; Doose, Gero; Hoffmann, Steve; Kretzmer, Helene; Langenberger, David; Binder, Hans; Hopp, Lydia; Kreuz, Markus; Loeffler, Markus; Rosolowski, Maciej; Korbel, Jan; Sungalee, Stefanie; Stadler, Peter F.; Zenz, Thorsten; Eils, Roland; Schlesner, Matthias; Diernfellner, Axel; Brunner, Michael

    2016-01-01

    The circadian clock and the cell cycle are major cellular systems that organize global physiology in temporal fashion. It seems conceivable that the potentially conflicting programs are coordinated. We show here that overexpression of MYC in U2OS cells attenuates the clock and conversely promotes cell proliferation while downregulation of MYC strengthens the clock and reduces proliferation. Inhibition of the circadian clock is crucially dependent on the formation of repressive complexes of MYC with MIZ1 and subsequent downregulation of the core clock genes BMAL1 (ARNTL), CLOCK and NPAS2. We show furthermore that BMAL1 expression levels correlate inversely with MYC levels in 102 human lymphomas. Our data suggest that MYC acts as a master coordinator that inversely modulates the impact of cell cycle and circadian clock on gene expression. PMID:27339797

  7. The effect of alterations in myc gene expression on B cell development in the bursa of Fabricius.

    PubMed

    Thompson, C B; Humphries, E H; Carlson, L M; Chen, C L; Neiman, P E

    1987-11-01

    Infection of 18-day embryonic bursal lymphocytes with a v-myc-containing retrovirus leads directly to a polyclonal proliferation of surface immunoglobulin-positive (slg+) cells in the bursa of Fabricius detected four weeks after hatching. These v-myc-expressing bursal cells repopulate the follicles of chemically ablated bursae more efficiently than total normal 18-day embryonic bursal cells. In contrast, comparable normal bursal cells lose the ability to repopulate follicles by four weeks. Bursal lymphocytes expressing either a retroviral v-myc or a c-myc gene deregulated by adjacent retroviral integration retain the ability of embryonic bursal lymphocytes to diversify their immunoglobulin light chain genes. These results suggest that retroviral deregulation of myc expression during avian B cell development induces outgrowth of a population of cells with the cardinal phenotypic characteristics of bursal stem cells. PMID:3499231

  8. MYC/MIZ1-dependent gene repression inversely coordinates the circadian clock with cell cycle and proliferation.

    PubMed

    Shostak, Anton; Ruppert, Bianca; Ha, Nati; Bruns, Philipp; Toprak, Umut H; Eils, Roland; Schlesner, Matthias; Diernfellner, Axel; Brunner, Michael

    2016-01-01

    The circadian clock and the cell cycle are major cellular systems that organize global physiology in temporal fashion. It seems conceivable that the potentially conflicting programs are coordinated. We show here that overexpression of MYC in U2OS cells attenuates the clock and conversely promotes cell proliferation while downregulation of MYC strengthens the clock and reduces proliferation. Inhibition of the circadian clock is crucially dependent on the formation of repressive complexes of MYC with MIZ1 and subsequent downregulation of the core clock genes BMAL1 (ARNTL), CLOCK and NPAS2. We show furthermore that BMAL1 expression levels correlate inversely with MYC levels in 102 human lymphomas. Our data suggest that MYC acts as a master coordinator that inversely modulates the impact of cell cycle and circadian clock on gene expression. PMID:27339797

  9. Rearrangements of c-myc and c-abl genes in tumour cells in Burkitt's lymphoma.

    PubMed Central

    Casares, S; Rodríguez, J M; Martin, A; Parrado, A

    1993-01-01

    Rearrangements of oncogenes c-myc and c-abl were detected by non-radioactive hybridisation in a case of Burkitt's lymphoma/leukaemia. The surface phenotype of Burkitt's cells were positive for CD19, CD20, HLA-DR, CD14, CD33 and surface immunoglobulin markers. Although cytogenetic analysis was not performed, the c-myc and heavy immunoglobulin genes had the same 14.2 kilobase EcoRI molecular size fragment, suggesting a possible t(8;14) translocation which is a common marker of this malignancy. The c-abl oncogene was also rearranged in DNA digested BamHI and EcoRI. The physiopathological implications of the rearranged c-abl gene are unknown, this being the first case, as for as is known, of Burkitt's lymphoma/leukaemia with a rearranged c-abl gene. Images PMID:8408711

  10. Gene expression profiling of MYC-driven tumor signatures in porcine liver stem cells by transcriptome sequencing

    PubMed Central

    Aravalli, Rajagopal N; Talbot, Neil C; Steer, Clifford J

    2015-01-01

    AIM: To identify the genes induced and regulated by the MYC protein in generating tumors from liver stem cells. METHODS: In this study, we have used an immortal porcine liver stem cell line, PICM-19, to study the role of c-MYC in hepatocarcinogenesis. PICM-19 cells were converted into cancer cells (PICM-19-CSCs) by overexpressing human MYC. To identify MYC-driven differential gene expression, transcriptome sequencing was carried out by RNA sequencing, and genes identified by this method were validated using real-time PCR. In vivo tumorigenicity studies were then conducted by injecting PICM-19-CSCs into the flanks of immunodeficient mice. RESULTS: Our results showed that MYC-overexpressing PICM-19 stem cells formed tumors in immunodeficient mice demonstrating that a single oncogene was sufficient to convert them into cancer cells (PICM-19-CSCs). By using comparative bioinformatics analyses, we have determined that > 1000 genes were differentially expressed between PICM-19 and PICM-19-CSCs. Gene ontology analysis further showed that the MYC-induced, altered gene expression was primarily associated with various cellular processes, such as metabolism, cell adhesion, growth and proliferation, cell cycle, inflammation and tumorigenesis. Interestingly, six genes expressed by PICM-19 cells (CDO1, C22orf39, DKK2, ENPEP, GPX6, SRPX2) were completely silenced after MYC-induction in PICM-19-CSCs, suggesting that the absence of these genes may be critical for inducing tumorigenesis. CONCLUSION: MYC-driven genes may serve as promising candidates for the development of hepatocellular carcinoma therapeutics that would not have deleterious effects on other cell types in the liver. PMID:25717234

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

    NASA Astrophysics Data System (ADS)

    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.

  12. Structure and expression of the human L-myc gene reveal a complex pattern of alternative mRNA processing

    SciTech Connect

    Kaye, F.; Battey, J.; Nau, M.; Brooks, B.; Seifter, E.; De Greve, J.; Birrer, M.; Sausville, E.; Minna, J.

    1988-01-01

    The authors' analyzed in detail the structure of the L-myc gene isolated from human placental DNA and characterized its expression in several small-cell lung cancer cell lines. The gene is composed of three exons and two introns spanning 6.6 kilobases in human DNA. Several distinct mRNA species are produced in all small-cell lung cancer cell lines that express L-myc. These transcripts are generated from a single gene by alternative splicing of introns 1 and 2 and by use of alternative polyadenylation signals. In some mRNAs that is a long open reading frame with a predicted translated protein of 364 residues. Amino acid sequence comparison with c-myc and N-myc demonstrated multiple discrete regions with extensive homology. In contrast, other mRNA transcripts, generated by alternative processing, could encode a truncated protein with a novel carboxy-terminal end.

  13. Myc and mRNA capping.

    PubMed

    Dunn, Sianadh; Cowling, Victoria H

    2015-05-01

    c-Myc is upregulated in response to growth factors and transmits the signal to proliferate by altering the gene expression landscape. When genetic alterations result in growth factor-independent c-Myc expression, it can become an oncogene. The majority of human tumour types exhibit a degree of c-Myc deregulation, resulting in unrestrained cell proliferation. c-Myc binds proximal to the promoter region of genes and recruits co-factors including histone acetyltransferases and RNA pol II kinases, which promote transcription. c-Myc also promotes formation of the cap structure at the 5' end of mRNA. The cap is 7-methylguanosine linked to the first transcribed nucleotide of RNA pol II transcripts via a 5' to 5' triphosphate bridge. The cap is added to the first transcribed nucleotide by the capping enzymes, RNGTT and RNMT-RAM. During the early stages of transcription, the capping enzymes are recruited to RNA pol II phosphorylated on Serine-5 of the C-terminal domain. The mRNA cap protects transcripts from degradation during transcription and recruits factors which promote RNA processing including, splicing, export and translation initiation. The proportion of transcripts with a cap structure is increased by elevating c-Myc expression, resulting in increased rates of translation. c-Myc promotes capping by promoting RNA pol II phosphorylation and by upregulating the enzyme SAHH which neutralises the inhibitory bi-product of methylation reactions, SAH. c-Myc-induced capping is required for c-Myc-dependent gene expression and cell proliferation. Targeting capping may represent a new therapeutic opportunity to inhibit c-Myc function in tumours. This article is part of a Special Issue entitled: Myc proteins in cell biology and pathology. PMID:24681440

  14. Genomic targets of the human c-Myc protein

    PubMed Central

    Fernandez, Paula C.; Frank, Scott R.; Wang, Luquan; Schroeder, Marianne; Liu, Suxing; Greene, Jonathan; Cocito, Andrea; Amati, Bruno

    2003-01-01

    The transcription factor Myc is induced by mitogenic signals and regulates downstream cellular responses. If overexpressed, Myc promotes malignant transformation. Myc modulates expression of diverse genes in experimental systems, but few are proven direct targets. Here, we present a large-scale screen for genomic Myc-binding sites in live human cells. We used bioinformatics to select consensus DNA elements (CACGTG or E-boxes) situated in the 5′ regulatory region of genes and measured Myc binding to those sequences in vivo by quantitative chromatin immunoprecipitation. Strikingly, most promoter-associated E-boxes showed selective recovery with Myc, unlike non-E-box promoters or E-boxes in bulk genomic DNA. Promoter E-boxes were distributed in two groups bound by Myc at distinct frequencies. The high-affinity group included an estimated 11% of all cellular loci, was highly conserved among different cells, and was bound independently of Myc expression levels. Overexpressed Myc associated at increased frequency with low-affinity targets and, at extreme levels, also with other sequences, suggesting that some binding was not sequence-specific. The strongest DNA-sequence parameter defining high-affinity targets was the location of E-boxes within CpG islands, correlating with an open, preacetylated state of chromatin. Myc further enhanced histone acetylation, with or without accompanying induction of mRNA expression. Our findings point to a high regulatory and biological diversity among Myc-target genes. PMID:12695333

  15. WDR5 Supports an N-Myc Transcriptional Complex That Drives a Protumorigenic Gene Expression Signature in Neuroblastoma.

    PubMed

    Sun, Yuting; Bell, Jessica L; Carter, Daniel; Gherardi, Samuele; Poulos, Rebecca C; Milazzo, Giorgio; Wong, Jason W H; Al-Awar, Rima; Tee, Andrew E; Liu, Pei Y; Liu, Bing; Atmadibrata, Bernard; Wong, Matthew; Trahair, Toby; Zhao, Quan; Shohet, Jason M; Haupt, Ygal; Schulte, Johannes H; Brown, Peter J; Arrowsmith, Cheryl H; Vedadi, Masoud; MacKenzie, Karen L; Hüttelmaier, Stefan; Perini, Giovanni; Marshall, Glenn M; Braithwaite, Antony; Liu, Tao

    2015-12-01

    MYCN gene amplification in neuroblastoma drives a gene expression program that correlates strongly with aggressive disease. Mechanistically, trimethylation of histone H3 lysine 4 (H3K4) at target gene promoters is a strict prerequisite for this transcriptional program to be enacted. WDR5 is a histone H3K4 presenter that has been found to have an essential role in H3K4 trimethylation. For this reason, in this study, we investigated the relationship between WDR5-mediated H3K4 trimethylation and N-Myc transcriptional programs in neuroblastoma cells. N-Myc upregulated WDR5 expression in neuroblastoma cells. Gene expression analysis revealed that WDR5 target genes included those with MYC-binding elements at promoters such as MDM2. We showed that WDR5 could form a protein complex at the MDM2 promoter with N-Myc, but not p53, leading to histone H3K4 trimethylation and activation of MDM2 transcription. RNAi-mediated attenuation of WDR5 upregulated expression of wild-type but not mutant p53, an effect associated with growth inhibition and apoptosis. Similarly, a small-molecule antagonist of WDR5 reduced N-Myc/WDR5 complex formation, N-Myc target gene expression, and cell growth in neuroblastoma cells. In MYCN-transgenic mice, WDR5 was overexpressed in precancerous ganglion and neuroblastoma cells compared with normal ganglion cells. Clinically, elevated levels of WDR5 in neuroblastoma specimens were an independent predictor of poor overall survival. Overall, our results identify WDR5 as a key cofactor for N-Myc-regulated transcriptional activation and tumorigenesis and as a novel therapeutic target for MYCN-amplified neuroblastomas. PMID:26471359

  16. Myc and cell cycle control.

    PubMed

    Bretones, Gabriel; Delgado, M Dolores; León, Javier

    2015-05-01

    Soon after the discovery of the Myc gene (c-Myc), it became clear that Myc expression levels tightly correlate to cell proliferation. The entry in cell cycle of quiescent cells upon Myc enforced expression has been described in many models. Also, the downregulation or inactivation of Myc results in the impairment of cell cycle progression. Given the frequent deregulation of Myc oncogene in human cancer it is important to dissect out the mechanisms underlying the role of Myc on cell cycle control. Several parallel mechanisms account for Myc-mediated stimulation of the cell cycle. First, most of the critical positive cell cycle regulators are encoded by genes induced by Myc. These Myc target genes include Cdks, cyclins and E2F transcription factors. Apart from its direct effects on the transcription, Myc is able to hyperactivate cyclin/Cdk complexes through the induction of Cdk activating kinase (CAK) and Cdc25 phosphatases. Moreover, Myc antagonizes the activity of cell cycle inhibitors as p21 and p27 through different mechanisms. Thus, Myc is able to block p21 transcription or to induce Skp2, a protein involved in p27 degradation. Finally, Myc induces DNA replication by binding to replication origins and by upregulating genes encoding proteins required for replication initiation. Myc also regulates genes involved in the mitotic control. A promising approach to treat tumors with deregulated Myc is the synthetic lethality based on the inhibition of Cdks. Thus, the knowledge of the Myc-dependent cell cycle regulatory mechanisms will help to discover new therapeutic approaches directed against malignancies with deregulated Myc. This article is part of a Special Issue entitled: Myc proteins in cell biology and pathology. PMID:24704206

  17. Joint Binding of OTX2 and MYC in Promotor Regions Is Associated with High Gene Expression in Medulloblastoma

    PubMed Central

    Bunt, Jens; Hasselt, Nancy E.; Zwijnenburg, Danny A.; Koster, Jan; Versteeg, Rogier; Kool, Marcel

    2011-01-01

    Both OTX2 and MYC are important oncogenes in medulloblastoma, the most common malignant brain tumor in childhood. Much is known about MYC binding to promoter regions, but OTX2 binding is hardly investigated. We used ChIP-on-chip data to analyze the binding patterns of both transcription factors in D425 medulloblastoma cells. When combining the data for all promoter regions in the genome, OTX2 binding showed a remarkable bi-modal distribution pattern with peaks around −250 bp upstream and +650 bp downstream of the transcription start sites (TSSs). Indeed, 40.2% of all OTX2-bound TSSs had more than one significant OTX2-binding peak. This OTX2-binding pattern was very different from the TSS-centered single peak binding pattern observed for MYC and other known transcription factors. However, in individual promoter regions, OTX2 and MYC have a strong tendency to bind in proximity of each other. OTX2-binding sequences are depleted near TSSs in the genome, providing an explanation for the observed bi-modal distribution of OTX2 binding. This contrasts to the enrichment of E-box sequences at TSSs. Both OTX2 and MYC binding independently correlated with higher gene expression. Interestingly, genes of promoter regions with multiple OTX2 binding as well as MYC binding showed the highest expression levels in D425 cells and in primary medulloblastomas. Genes within this class of promoter regions were enriched for medulloblastoma and stem cell specific genes. Our data suggest an important functional interaction between OTX2 and MYC in regulating gene expression in medulloblastoma. PMID:22016811

  18. Elimination of extrachromosomally amplified MYC genes from human tumor cells reduces their tumorigenicity.

    PubMed Central

    Von Hoff, D D; McGill, J R; Forseth, B J; Davidson, K K; Bradley, T P; Van Devanter, D R; Wahl, G M

    1992-01-01

    Oncogene amplification has been observed in a broad spectrum of human tumors and has been associated with a poor prognosis for patients with several different types of malignancies. Importantly, at biopsy, the amplified genes localize to acentric extrachromosomal elements such as double-minute chromosomes (DMs) in the vast majority of cases. We show here that treatment of several human tumor cell lines with low concentrations of hydroxyurea accelerates the loss of their extrachromosomally amplified oncogenes. The decreases in MYC copy number in a human tumor cell line correlated with a dramatic reduction in cloning efficiency in soft agar and tumorigenicity in nude mice. No effect on gene copy number or tumorigenicity was observed for a closely related cell line containing the same number of chromosomally amplified MYC genes. One step involved in the accelerated loss of extrachromosomal elements is shown to involve their preferential entrapment of DMs within micronuclei. The data suggest that agents that accelerate the loss of extrachromosomally amplified genes could provide valuable tools for moderating the growth of a large number of human neoplasms. Images PMID:1518843

  19. Pleiotropic derepression of developmentally regulated cellular and viral genes by c-myc protooncogene products in undifferentiated embryonal carcinoma cells.

    PubMed Central

    Onclercq, R; Lavenu, A; Cremisi, C

    1989-01-01

    We show here in mouse embryonal carcinoma (EC) cells that the endo A gene is negatively regulated and shares negative transacting factors with the Py and SV40 viruses. The products of the proto-oncogene c-myc derepress at the transcriptional level the appropriately initiated expression of the endo A gene and activate the Py early promoter in EC stem cells. C-myc products also activate the endo A and the Py early promoters in TDM epithelial cells, and the Py early promoter in 3T6 cells in which the two genes are already expressed or can be expressed. Furthermore we show that the myc exon 1 is essential for activation and that this activation might be mediated by AP1 family factors. Images PMID:2536923

  20. A Core MYC Gene Expression Signature Is Prominent in Basal-Like Breast Cancer but Only Partially Overlaps the Core Serum Response

    PubMed Central

    Chandriani, Sanjay; Frengen, Eirik; Cowling, Victoria H.; Pendergrass, Sarah A.; Perou, Charles M.; Whitfield, Michael L.; Cole, Michael D.

    2009-01-01

    Background The MYC oncogene contributes to induction and growth of many cancers but the full spectrum of the MYC transcriptional response remains unclear. Methodology/Principal Findings Using microarrays, we conducted a detailed kinetic study of genes that respond to MYCN or MYCNΔMBII induction in primary human fibroblasts. In parallel, we determined the response to steady state overexpression of MYCN and MYCNΔMBII in the same cell type. An overlapping set of 398 genes from the two protocols was designated a ‘Core MYC Signature’ and used for further analysis. Comparison of the Core MYC Signature to a published study of the genes induced by serum stimulation revealed that only 7.4% of the Core MYC Signature genes are in the Core Serum Response and display similar expression changes to both MYC and serum. Furthermore, more than 50% of the Core MYC Signature genes were not influenced by serum stimulation. In contrast, comparison to a panel of breast cancers revealed a strong concordance in gene expression between the Core MYC Signature and the basal-like breast tumor subtype, which is a subtype with poor prognosis. This concordance was supported by the higher average level of MYC expression in the same tumor samples. Conclusions/Significance The Core MYC Signature has clinical relevance as this profile can be used to deduce an underlying genetic program that is likely to contribute to a clinical phenotype. Therefore, the presence of the Core MYC Signature may predict clinical responsiveness to therapeutics that are designed to disrupt MYC-mediated phenotypes. PMID:19690609

  1. MYC-repressed long noncoding RNAs antagonize MYC-induced cell proliferation and cell cycle progression

    PubMed Central

    Jeon, Young-Jun; Fadda, Paolo; Alder, Hansjuerg; Croce, Carlo M.

    2015-01-01

    The transcription factor MYC is a proto-oncogene regulating cell proliferation, cell cycle, apoptosis and metabolism. The recent identification of MYC-regulated long noncoding RNAs (lncRNAs) expands our knowledge of the role of lncRNAs in MYC functions. Here, we identify MYC-repressed lncRNAs named MYCLo-4, -5 and -6 by comparing 3 categories of lncRNAs (downregulated in highly MYC-expressing colorectal cancer, up-regulated by MYC knockdown in HCT116, upregulated by MYC knockdown in RKO). The MYC-repressed MYCLos are implicated in MYC-modulated cell proliferation through cell cycle regulation. By screening cell cycle-related genes regulated by MYC and the MYC-repressed MYCLos, we identified the MYC-repressed gene GADD45A as a target gene of the MYC-repressed MYCLos such as MYCLo-4 and MYCLo-6. PMID:26003165

  2. c-myc gene sequences and the phylogeny of bats and other eutherian mammals.

    PubMed

    Miyamoto, M M; Porter, C A; Goodman, M

    2000-09-01

    The complete protein-coding sequences of the c-myc proto-oncogene were determined for five species of four new orders of eutherian (placental) mammals. These newly obtained sequences were aligned to each other and to other available orthologs for the phylogenetic estimation of eutherian interordinal relationships. Several measures of sequence difference and base composition were first calculated to assess the major evolutionary properties of the three codon positions and two protein-coding exons of the gene. On the basis of these calculations, different parsimony, distance, and maximum likelihood approaches were adopted, with the most sophisticated involving the separate, then combined, likelihood analyses of the third codon positions of exon 2 versus all other sites. These phylogenetic approaches provided clear support for the grouping of Chiroptera (bats) with Artiodactyla (ruminants, camels, and pigs) and Carnivora (cats, dogs, and their allies), an interordinal arrangement that receives strong corroboration from other lines of evidence including complete mitochondrial DNA sequences. In contrast, these analyses failed to provide strong to reasonable support for any other interordinal group. This study concludes with specific recommendations about sampling and other strategies for maximizing the phylogenetic contributions of the c-myc gene to the continued resolution of the eutherian ordinal tree. PMID:12116424

  3. MUC1-C drives MYC in multiple myeloma.

    PubMed

    Tagde, Ashujit; Rajabi, Hasan; Bouillez, Audrey; Alam, Maroof; Gali, Reddy; Bailey, Shannon; Tai, Yu-Tzu; Hideshima, Teru; Anderson, Kenneth; Avigan, David; Kufe, Donald

    2016-05-26

    Multiple myeloma (MM) cell lines and primary tumor cells are addicted to the MYC oncoprotein for survival. Little is known, however, about how MYC expression is upregulated in MM cells. The mucin 1 C-terminal subunit (MUC1-C) is an oncogenic transmembrane protein that is aberrantly expressed in MM cell lines and primary tumor samples. The present studies demonstrate that targeting MUC1-C with silencing by clustered regularly interspaced short palindromic repeat (CRISPR)/CRISPR-associated protein 9 editing or with the GO-203 inhibitor is associated with downregulation of MYC messenger RNA and protein. The results show that MUC1-C occupies the MYC promoter and thereby activates the MYC gene by a β-catenin/transcription factor 4 (TCF4)-mediated mechanism. In this way, MUC1-C (1) increases β-catenin occupancy on the MYC promoter, (2) forms a complex with β-catenin and TCF4, and, in turn, (3) drives MYC transcription. Analysis of MM cells using quantitative real-time reverse transcription polymerase chain reaction arrays further demonstrated that silencing MUC1-C is associated with downregulation of MYC target genes, including CCND2, hTERT, and GCLC Analysis of microarray data sets further demonstrated that MUC1 levels positively correlate with MYC expression in MM progression and in primary cells from over 800 MM patients. These findings collectively provide convincing evidence that MUC1-C drives MYC expression in MM. PMID:26907633

  4. Differential expression of c-myc gene and c-fos gene in premalignant and malignant tissues from patients with familial polyposis coli.

    PubMed

    Sugio, K; Kurata, S; Sasaki, M; Soejima, J; Sasazuki, T

    1988-09-01

    The expression of 8 oncogenes and the structures of 19 oncogenes were analyzed in 15 adenocarcinomas (12 primary and 3 metastatic), 18 adenomatous polyps, and 18 normal colonic mucosae derived from 19 patients with familial polyposis coli. The expression of c-myc gene was most elevated in carcinoma, and moderately elevated in adenoma, compared with corresponding normal colonic mucosa. In contrast, the expression of c-fos gene was markedly decreased in all samples of adenoma and carcinoma, compared with that of normal colonic mucosa. These characteristic expression patterns of c-myc and c-fos genes were revealed not only in familial polyposis coli but also in cases of nonhereditary colon carcinoma. Structures of the 19 oncogenes were not modified in either adenoma or carcinoma, except for amplification of the c-myc gene detected in one carcinoma, but not in adenoma, from the same patient. Analyses of the amplified c-myc gene suggest that gene duplication may relate to the mechanism of gene amplification. Thus, the enhanced expression of c-myc gene in adenoma and carcinoma may reflect the proliferative activity, while the c-fos gene may be a prerequisite to stabilize the state of terminal differentiation of colonic epithelial cells. PMID:2842040

  5. Expression of c-myc and mutation of the KRAS gene in patients with ovarian mucinous tumors.

    PubMed

    Li, X S; Sun, J; He, X L

    2015-01-01

    We examined the expression of c-myc and mutations in the KRAS gene in ovarian mucinous tumors to explore the pathogenesis of these tumors and the feasibility of targeted gene therapy. Expression of c-myc protein and mutations in the KRAS gene in 24 cases of ovarian mucinous cystadenoma, 46 cases of ovarian borderline mucinous cystadenoma, and 46 cases of ovarian mucinous cystadenocarcinoma were detected using the immunohistochemistry PV-9000 2-step method and polymerase chain reaction-restriction fragment length polymorphism. The positive expression rates of c-myc in ovarian mucinous cystadenoma, borderline mucinous cystadenoma, and cystadenocarcinoma were 0, 39.1, and 65.2%, respectively (P < 0.01), while the mutation rates in KRAS were 0, 39.1 and 13.0%, respectively. The mutation rate of the borderline group was significantly higher, while rates in the other 2 groups were similar (P > 0.05). c-myc was not correlated with clinical stage, pathological grade, or age of patients with ovarian mucinous cystadenocarcinoma or borderline mucinous cystadenoma (P > 0.05), but was correlated with tumor size (P < 0.05). Mutations in KRAS were not correlated with clinical stage or tumor size in patients with borderline mucinous cystadenoma (P > 0.05), whereas it was correlated with age (P < 0.05). In borderline mucinous cystadenoma, c-myc expression and KRAS mutations were not correlated (P > 0.05). c-myc is involved in the formation of ovarian borderline mucinous cystadenoma and mucinous cystadenocarcinoma, and the KRAS gene may contribute to the formation of borderline mucinous cystadenoma. PMID:26400304

  6. Myc Inhibits p27-Induced Erythroid Differentiation of Leukemia Cells by Repressing Erythroid Master Genes without Reversing p27-Mediated Cell Cycle Arrest▿ ‡

    PubMed Central

    Acosta, Juan C.; Ferrándiz, Nuria; Bretones, Gabriel; Torrano, Verónica; Blanco, Rosa; Richard, Carlos; O'Connell, Brenda; Sedivy, John; Delgado, M. Dolores; León, Javier

    2008-01-01

    Inhibition of differentiation has been proposed as an important mechanism for Myc-induced tumorigenesis, but the mechanisms involved are unclear. We have established a genetically defined differentiation model in human leukemia K562 cells by conditional expression of the cyclin-dependent kinase (Cdk) inhibitor p27 (inducible by Zn2+) and Myc (activatable by 4-hydroxy-tamoxifen). Induction of p27 resulted in erythroid differentiation, accompanied by Cdk inhibition and G1 arrest. Interestingly, activation of Myc inhibited p27-mediated erythroid differentiation without affecting p27-mediated proliferation arrest. Microarray-based gene expression indicated that, in the presence of p27, Myc blocked the upregulation of several erythroid-cell-specific genes, including NFE2, JUNB, and GATA1 (transcription factors with a pivotal role in erythropoiesis). Moreover, Myc also blocked the upregulation of Mad1, a transcriptional antagonist of Myc that is able to induce erythroid differentiation. Cotransfection experiments demonstrated that Myc-mediated inhibition of differentiation is partly dependent on the repression of Mad1 and GATA1. In conclusion, this model demonstrates that Myc-mediated inhibition of differentiation depends on the regulation of a specific gene program, whereas it is independent of p27-mediated cell cycle arrest. Our results support the hypothesis that differentiation inhibition is an important Myc tumorigenic mechanism that is independent of cell proliferation. PMID:18838534

  7. Myc inhibits p27-induced erythroid differentiation of leukemia cells by repressing erythroid master genes without reversing p27-mediated cell cycle arrest.

    PubMed

    Acosta, Juan C; Ferrándiz, Nuria; Bretones, Gabriel; Torrano, Verónica; Blanco, Rosa; Richard, Carlos; O'Connell, Brenda; Sedivy, John; Delgado, M Dolores; León, Javier

    2008-12-01

    Inhibition of differentiation has been proposed as an important mechanism for Myc-induced tumorigenesis, but the mechanisms involved are unclear. We have established a genetically defined differentiation model in human leukemia K562 cells by conditional expression of the cyclin-dependent kinase (Cdk) inhibitor p27 (inducible by Zn(2+)) and Myc (activatable by 4-hydroxy-tamoxifen). Induction of p27 resulted in erythroid differentiation, accompanied by Cdk inhibition and G(1) arrest. Interestingly, activation of Myc inhibited p27-mediated erythroid differentiation without affecting p27-mediated proliferation arrest. Microarray-based gene expression indicated that, in the presence of p27, Myc blocked the upregulation of several erythroid-cell-specific genes, including NFE2, JUNB, and GATA1 (transcription factors with a pivotal role in erythropoiesis). Moreover, Myc also blocked the upregulation of Mad1, a transcriptional antagonist of Myc that is able to induce erythroid differentiation. Cotransfection experiments demonstrated that Myc-mediated inhibition of differentiation is partly dependent on the repression of Mad1 and GATA1. In conclusion, this model demonstrates that Myc-mediated inhibition of differentiation depends on the regulation of a specific gene program, whereas it is independent of p27-mediated cell cycle arrest. Our results support the hypothesis that differentiation inhibition is an important Myc tumorigenic mechanism that is independent of cell proliferation. PMID:18838534

  8. The Expression and Localization of N-Myc Downstream-Regulated Gene 1 in Human Trophoblasts

    PubMed Central

    Shi, Xiao-Hua; Larkin, Jacob C.; Chen, Baosheng; Sadovsky, Yoel

    2013-01-01

    The protein N-Myc downstream-regulated gene 1 (NDRG1) is implicated in the regulation of cell proliferation, differentiation, and cellular stress response. NDRG1 is expressed in primary human trophoblasts, where it promotes cell viability and resistance to hypoxic injury. The mechanism of action of NDRG1 remains unknown. To gain further insight into the intracellular action of NDRG1, we analyzed the expression pattern and cellular localization of endogenous NDRG1 and transfected Myc-tagged NDRG1 in human trophoblasts exposed to diverse injuries. In standard conditions, NDRG1 was diffusely expressed in the cytoplasm at a low level. Hypoxia or the hypoxia mimetic cobalt chloride, but not serum deprivation, ultraviolet (UV) light, or ionizing radiation, induced the expression of NDRG1 in human trophoblasts and the redistribution of NDRG1 into the nucleus and cytoplasmic membranes associated with the endoplasmic reticulum (ER) and microtubules. Mutation of the phosphopantetheine attachment site (PPAS) within NDRG1 abrogated this pattern of redistribution. Our results shed new light on the impact of cell injury on NDRG1 expression patterns, and suggest that the PPAS domain plays a key role in NDRG1’s subcellular distribution. PMID:24066183

  9. The Action Mechanism of the Myc Inhibitor Termed Omomyc May Give Clues on How to Target Myc for Cancer Therapy

    PubMed Central

    Savino, Mauro; Annibali, Daniela; Carucci, Nicoletta; Favuzzi, Emilia; Cole, Michael D.; Evan, Gerard I.; Soucek, Laura; Nasi, Sergio

    2011-01-01

    Recent evidence points to Myc – a multifaceted bHLHZip transcription factor deregulated in the majority of human cancers – as a priority target for therapy. How to target Myc is less clear, given its involvement in a variety of key functions in healthy cells. Here we report on the action mechanism of the Myc interfering molecule termed Omomyc, which demonstrated astounding therapeutic efficacy in transgenic mouse cancer models in vivo. Omomyc action is different from the one that can be obtained by gene knockout or RNA interference, approaches designed to block all functions of a gene product. This molecule – instead – appears to cause an edge-specific perturbation that destroys some protein interactions of the Myc node and keeps others intact, with the result of reshaping the Myc transcriptome. Omomyc selectively targets Myc protein interactions: it binds c- and N-Myc, Max and Miz-1, but does not bind Mad or select HLH proteins. Specifically, it prevents Myc binding to promoter E-boxes and transactivation of target genes while retaining Miz-1 dependent binding to promoters and transrepression. This is accompanied by broad epigenetic changes such as decreased acetylation and increased methylation at H3 lysine 9. In the presence of Omomyc, the Myc interactome is channeled to repression and its activity appears to switch from a pro-oncogenic to a tumor suppressive one. Given the extraordinary therapeutic impact of Omomyc in animal models, these data suggest that successfully targeting Myc for cancer therapy might require a similar twofold action, in order to prevent Myc/Max binding to E-boxes and, at the same time, keep repressing genes that would be repressed by Myc. PMID:21811581

  10. MYC is a critical target of FBXW7

    PubMed Central

    Sato, Mai; Rodriguez-Barrueco, Ruth; Yu, Jiyang; Do, Catherine; Silva, Jose M.; Gautier, Jean

    2015-01-01

    MYC deregulation is a driver of many human cancers. Altering the balance of MYC protein levels at the level of transcription, protein stability, or turnover is sufficient to transform cells to a tumorigenic phenotype. While direct targeting of MYC is difficult, specific genetic vulnerabilities of MYC-deregulated cells could be exploited to selectively inhibit their growth. Using a genome-wide shRNA screen, we identified 78 candidate genes, which are required for survival of human mammary epithelial cells with elevated MYC levels. Among the candidates, we validated and characterized FBXW7, a component of the SCF-like ubiquitin ligase complex that targets MYC for proteasomal degradation. Down-regulation of FBXW7 leads to synergistic accumulation of cellular and active chromatin-bound MYC, while protein levels of other FBXW7 targets appear unaffected. Over a four-week time course, continuous FBXW7 down-regulation and MYC activation together cause an accumulation of cells in S-phase and G2/M-phase of the cell cycle. Under these conditions, we also observe elevated chromatin-bound levels of CDC45, suggesting increased DNA replication stress. Consistent with these results, FBXW7 down-regulation alone decreases the survival of T47D breast cancer cells. These results establish that FBXW7 down-regulation is synthetic lethal with MYC, and that MYC is a critical target of FBXW7 in breast epithelial cells. PMID:25669969

  11. Overexpression of c-myc in diabetic mice restores altered expression of the transcription factor genes that regulate liver metabolism.

    PubMed Central

    Riu, Efren; Ferre, Tura; Mas, Alex; Hidalgo, Antonio; Franckhauser, Sylvie; Bosch, Fatima

    2002-01-01

    Overexpression of the c-Myc transcription factor in liver induces glucose uptake and utilization. Here we examined the effects of c- myc overexpression on the expression of hepatocyte-specific transcription factor genes which regulate the expression of genes controlling hepatic metabolism. At 4 months after streptozotocin (STZ) treatment, most diabetic control mice were highly hyperglycaemic and died, whereas in STZ-treated transgenic mice hyperglycaemia was markedly lower, the serum levels of beta-hydroxybutyrate, triacylglycerols and non-esterified fatty acids were normal, and they had greater viability in the absence of insulin. Furthermore, long-term STZ-treated transgenic mice showed similar glucose utilization and storage to healthy controls. This was consistent with the expression of glycolytic genes becoming normalized. In addition, restoration of gene expression of the transcription factor, sterol receptor element binding protein 1c, was observed in the livers of these transgenic mice. Further, in STZ-treated transgenic mice the expression of genes involved in the control of gluconeogenesis (phosphoenolpyruvate carbokykinase), ketogenesis (3-hydroxy-3-methylglutaryl-CoA synthase) and energy metabolism (uncoupling protein 2) had returned to normal. These findings were correlated with decreased expression of genes encoding the transcription factors hepatocyte nuclear factor 3gamma, peroxisome proliferator-activated receptor alpha and retinoid X receptor. These results indicate that c- myc overexpression may counteract diabetic changes by controlling hepatic glucose metabolism, both directly by altering the expression of metabolic genes and through the expression of key transcription factor genes. PMID:12230428

  12. Multiple single-stranded cis elements are associated with activated chromatin of the human c-myc gene in vivo.

    PubMed Central

    Michelotti, G A; Michelotti, E F; Pullner, A; Duncan, R C; Eick, D; Levens, D

    1996-01-01

    Transcription activation and repression of eukaryotic genes are associated with conformational and topological changes of the DNA and chromatin, altering the spectrum of proteins associated with an active gene. Segments of the human c-myc gene possessing non-B structure in vivo located with enzymatic and chemical probes. Sites hypertensive to cleavage with single-strand-specific S1 nuclease or the single-strand-selective agent potassium permanganate included the major promoters P1 and P2 as well as the far upstream sequence element (FUSE) and CT elements, which bind, respectively, the single-strand-specific factors FUSE-binding protein and heterogeneous nuclear ribonucleoprotein K in vitro. Active and inactive c-myc genes yielded different patterns of S1 nuclease and permanganate sensitivity, indicating alternative chromatin configurations of active and silent genes. The melting of specific cis elements of active c-myc genes in vivo suggested that transcriptionally associated torsional strain might assist strand separation and facilitate factor binding. Therefore, the interaction of FUSE-binding protein and heterogeneous nuclear ribonucleoprotein K with supercoiled DNA was studied. Remarkably, both proteins recognize their respective elements torsionally strained but not as liner duplexes. Single-strand- or supercoil-dependent gene regulatory proteins may directly link alterations in DNA conformation and topology with changes in gene expression. PMID:8649373

  13. Bombesin stimulation of c-fos and c-myc gene expression in cultured of Swiss 3T3 cells

    SciTech Connect

    Palumbo, A.P.; Rossino, P.; Comoglio, P.M.

    1986-11-01

    Bombesin has been show to be a potent mitogen for Swiss 3T3 cells. At nanomolar concentrations it stimulates DNA synthesis in quiescent cultures of 3T3 cells and also induces the expression of c-fos and c-myc mRNA. c-fos mRNA transcripts dramatically increase 15 min after the addition of bombesin, are still abundant after 30-60 min and then decrease. c-myc mRNA induction is detectable later, 1 h after bombesin treatment. Conversely, no changes in c-Ki-ras expression are observed after stimulation with bombesin. These results demonstrate that the increased expression of c-fos and c-myc mRNAs appears to be a common response to diverse agents that induce DNA synthesis and cell proliferation.

  14. Association Between Amplification and Expression of C-MYC Gene and Clinicopathological Characteristics of Stomach Cancer

    PubMed Central

    Khaleghian, Malihea; Jahanzad, Issa; Shakoori, Abbas; Emami Razavi, Amirnader; Azimi, Cyrus

    2016-01-01

    Background: The incidence rate of gastric cancer in western countries has shown a remarkable decline in the recent years while it is still the most common cancer among males in Iran. The proto-oncogene MYC, located at 8q24.1, regulates almost 15% of human genes and is activated in 20% of all tumors. The amplification of MYC and overexpression of its protein product are observed in 15 - 30% of gastric neoplasias. Objectives: The objective of this study was to find the preferences of Chromogenic In Situ Hybridization (CISH) and Immunohistochemistry (IHC) in diagnosis and prognosis of gastric cancer. Patients and Methods: We studied 102 samples of gastric cancer in Iran and all the patients had undergone primary surgical resection at the Cancer Institute Hospital, Tehran University of Medical Sciences. The CISH and IHC techniques were applied for all our samples. All of the samples had adenocarcinoma gastric cancer and were selected randomly. Also, the type of study was cross sectional. The sample size was 100 patients. Results: Our data revealed that both diffuse and intestinal types of gastric cancer occurred significantly more in males than females. Our results showed that there was an indication of some correlation between grades and CISH, although the difference was not significant. Our data also showed that CISH positive patients (43%) were more frequent compared to IHC positive patients (14.7%). There was a correlation between CISH and IHC. These results revealed that there was a significant difference between grades and IHC. There was also no statistical difference between CISH amplification in diffuse and intestinal types. Conclusions: From the results, it could be concluded that for administration of the treatment of stomach cancer, and progress and prognosis of tumor, which is important for patients and clinicians, the CISH is a better and more feasible test than IHC, in regards to sensitivity and specificity. PMID:27175302

  15. Survivin enhances telomerase activity via up-regulation of specificity protein 1- and c-Myc-mediated human telomerase reverse transcriptase gene transcription

    SciTech Connect

    Endoh, Teruo; Tsuji, Naoki; Asanuma, Koichi; Yagihashi, Atsuhito; Watanabe, Naoki . E-mail: watanabn@sapmed.ac.jp

    2005-05-01

    Suppression of apoptosis is thought to contribute to carcinogenesis. Survivin, a member of the inhibitor-of-apoptosis family, blocks apoptotic signaling activated by various cellular stresses. Since elevated expression of survivin observed in human cancers of varied origin was associated with poor patient survival, survivin has attracted growing attention as a potential target for cancer treatment. Immortalization of cells also is required for carcinogenesis; telomere length maintenance by telomerase is required for cancer cells to proliferate indefinitely. Yet how cancer cells activate telomerase remains unclear. We therefore examined possible interrelationships between survivin expression and telomerase activity. Correlation between survivin and human telomerase reverse transcriptase (hTERT) expression was observed in colon cancer tissues, and overexpression of survivin enhanced telomerase activity by up-regulation of hTERT expression in LS180 human colon cancer cells. DNA-binding activities of specificity protein 1 (Sp1) and c-Myc to the hTERT core promoter were increased in survivin gene transfectant cells. Phosphorylation of Sp1 and c-Myc at serine and threonine residues was enhanced by survivin, while total amounts of these proteins were unchanged. Further, 'knockdown' of survivin by a small inhibitory RNA decreased Sp1 and c-Myc phosphorylation. Thus survivin participates not only in inhibition of apoptosis, but also in prolonging cellular lifespan.

  16. Myc-induced SUMOylation is a therapeutic vulnerability for B-cell lymphoma

    PubMed Central

    Hoellein, Alexander; Fallahi, Mohammad; Schoeffmann, Stephanie; Steidle, Sabine; Schaub, Franz X.; Rudelius, Martina; Laitinen, Iina; Nilsson, Lisa; Goga, Andrei; Peschel, Christian; Nilsson, Jonas A.; Cleveland, John L.

    2014-01-01

    Myc oncogenic transcription factors (c-Myc, N-Myc, and L-Myc) coordinate the control of cell growth, division, and metabolism. In cancer, Myc overexpression is often associated with aggressive disease, which is in part due to the destruction of select targets by the ubiquitin-proteasome system (eg, SCFSkp2-directed destruction of the Cdk inhibitor p27Kip1). We reasoned that Myc would also regulate SUMOylation, a related means of posttranslational modification of proteins, and that this circuit would play essential roles in Myc-dependent tumorigenesis. Here, we report marked increases in the expression of genes that encode regulators and components of the SUMOylation machinery in mouse and human Myc-driven lymphomas, resulting in hyper-SUMOylation in these tumors. Further, inhibition of SUMOylation by genetic means disables Myc-induced proliferation, triggering G2/M cell-cycle arrest, polyploidy, and apoptosis. Using genetically defined cell models and conditional expression systems, this response was shown to be Myc specific. Finally, in vivo loss-of-function and pharmacologic studies demonstrated that inhibition of SUMOylation provokes rapid regression of Myc-driven lymphoma. Thus, targeting SUMOylation represents an attractive therapeutic option for lymphomas with MYC involvement. PMID:25143484

  17. Decoding c-Myc networks of cell cycle and apoptosis regulated genes in a transgenic mouse model of papillary lung adenocarcinomas

    PubMed Central

    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

  18. Jasmonic acid promotes degreening via MYC2/3/4- and ANAC019/055/072-mediated regulation of major chlorophyll catabolic genes.

    PubMed

    Zhu, Xiaoyu; Chen, Junyi; Xie, Zuokun; Gao, Jiong; Ren, Guodong; Gao, Shan; Zhou, Xin; Kuai, Benke

    2015-11-01

    Degreening caused by rapid chlorophyll (Chl) degradation is a characteristic event during green organ senescence or maturation. Pheophorbide a oxygenase gene (PAO) encodes a key enzyme of Chl degradation, yet its transcriptional regulation remains largely unknown. Using yeast one-hybrid screening, coupled with in vitro and in vivo assays, we revealed that Arabidopsis MYC2/3/4 basic helix-loop-helix proteins directly bind to PAO promoter. Overexpression of the MYCs significantly enhanced the transcriptional activity of PAO promoter in Arabidopsis protoplasts, and methyl jasmonate (MeJA) treatment greatly induced PAO expression in wild-type Arabidopsis plants, but the induction was abolished in mycmycmyc4. In addition, MYC2/3/4 proteins could promote the expression of another Chl catabolic enzyme gene, NYC1, as well as a key regulatory gene of Chl degradation, NYE1/SGR1, by directly binding to their promoters. More importantly, the mycmycmyc4 triple mutant showed a severe stay-green phenotype, whereas the lines overexpressing the MYCs showed accelerated leaf yellowing upon MeJA treatment. These results suggest that MYC2/3/4 proteins may mediate jasmonic acid (JA)-induced Chl degradation by directly activating these Chl catabolic genes (CCGs). Three NAC family proteins, ANAC019/055/072, downstream from MYC2/3/4 proteins, could also directly promote the expression of a similar set of CCGs (NYE1/SGR1, NYE2/SGR2 and NYC1) during Chl degradation. In particular, anac019 anac055 anac072 triple mutant displayed a severe stay-green phenotype after MeJA treatment. Finally, we revealed that MYC2 and ANAC019 may interact with each other and synergistically enhance NYE1 expression. Together, our study reveals a hierarchical and coordinated regulatory network of JA-induced Chl degradation. PMID:26407000

  19. DNA binding and antigene activity of a daunomycin-conjugated triplex-forming oligonucleotide targeting the P2 promoter of the human c-myc gene

    PubMed Central

    Carbone, Giuseppina M.; McGuffie, Eileen; Napoli, Sara; Flanagan, Courtney E.; Dembech, Chiara; Negri, Umberto; Arcamone, Federico; Capobianco, Massimo L.; Catapano, Carlo V.

    2004-01-01

    Triplex-forming oligonucleotides (TFO) that bind DNA in a sequence-specific manner might be used as selective repressors of gene expression and gene-targeted therapeutics. However, many factors, including instability of triple helical complexes in cells, limit the efficacy of this approach. In the present study, we tested whether covalent linkage of a TFO to daunomycin, which is a potent DNA-intercalating agent and anticancer drug, could increase stability of the triple helix and activity of the oligonucleotide in cells. The 11mer daunomycin-conjugated GT (dauno-GT11) TFO targeted a sequence upstream of the P2 promoter, a site known to be critical for transcription of the c-myc gene. Band-shift assays showed that the dauno-GT11 formed triplex DNA with enhanced stability compared to the unmodified TFO. Band shift and footprinting experiments demonstrated that binding of dauno-GT11 was highly sequence-specific with exclusive binding to the 11 bp target site in the c-myc promoter. The daunomycin-conjugated TFO inhibited transcription in vitro and reduced c-myc promoter activity in prostate and breast cancer cells. The daunomycin-conjugated TFO was taken up by cells with a distinctive intracellular distribution compared to free daunomycin. However, cationic lipid-mediated delivery was required for enhanced cellular uptake, nuclear localization and biological activity of the TFO in cells. Dauno-GT11 reduced transcription of the endogenous c-myc gene in cells, but did not affect expression of non-target genes, such as ets-1 and ets-2, which contained very similar target sequences in their promoters. Daunomycin-conjugated control oligonucleotides unable to form triplex DNA with the target sequence did not have any effect in these assays, indicating that daunomycin was not directly responsible for the activity of daunomycin-conjugated TFO. Thus, attachment of daunomycin resulted in increased triplex stability and biological activity of the 11mer GT-rich TFO without

  20. Insertional mutagenesis and deep profiling reveals gene hierarchies and a Myc/p53-dependent bottleneck in lymphomagenesis.

    PubMed

    Huser, Camille A; Gilroy, Kathryn L; de Ridder, Jeroen; Kilbey, Anna; Borland, Gillian; Mackay, Nancy; Jenkins, Alma; Bell, Margaret; Herzyk, Pawel; van der Weyden, Louise; Adams, David J; Rust, Alistair G; Cameron, Ewan; Neil, James C

    2014-02-01

    Retroviral insertional mutagenesis (RIM) is a powerful tool for cancer genomics that was combined in this study with deep sequencing (RIM/DS) to facilitate a comprehensive analysis of lymphoma progression. Transgenic mice expressing two potent collaborating oncogenes in the germ line (CD2-MYC, -Runx2) develop rapid onset tumours that can be accelerated and rendered polyclonal by neonatal Moloney murine leukaemia virus (MoMLV) infection. RIM/DS analysis of 28 polyclonal lymphomas identified 771 common insertion sites (CISs) defining a 'progression network' that encompassed a remarkably large fraction of known MoMLV target genes, with further strong indications of oncogenic selection above the background of MoMLV integration preference. Progression driven by RIM was characterised as a Darwinian process of clonal competition engaging proliferation control networks downstream of cytokine and T-cell receptor signalling. Enhancer mode activation accounted for the most efficiently selected CIS target genes, including Ccr7 as the most prominent of a set of chemokine receptors driving paracrine growth stimulation and lymphoma dissemination. Another large target gene subset including candidate tumour suppressors was disrupted by intragenic insertions. A second RIM/DS screen comparing lymphomas of wild-type and parental transgenics showed that CD2-MYC tumours are virtually dependent on activation of Runx family genes in strong preference to other potent Myc collaborating genes (Gfi1, Notch1). Ikzf1 was identified as a novel collaborating gene for Runx2 and illustrated the interface between integration preference and oncogenic selection. Lymphoma target genes for MoMLV can be classified into (a) a small set of master regulators that confer self-renewal; overcoming p53 and other failsafe pathways and (b) a large group of progression genes that control autonomous proliferation in transformed cells. These findings provide insights into retroviral biology, human cancer genetics

  1. Myc and PI3K/AKT signaling cooperatively repress FOXO3a-dependent PUMA and GADD45a gene expression

    PubMed Central

    Amente, Stefano; Zhang, Jiyuan; Lubrano Lavadera, Miriam; Lania, Luigi; Avvedimento, Enrico Vittorio; Majello, Barbara

    2011-01-01

    Growth factor withdrawal inhibits cell cycle progression by stimulating expression of growth-arresting genes through the activation of Forkhead box O transcription factors such as FOXO3a, which binds to the FHRE-responsive elements of a number of target genes such as PUMA and GADD45a. Following exposure of cells to growth factors FOXO3a-mediated transcription is rapidly repressed. We determined that repression correlates with activation of PI3K/AKT pathway leading to FOXO3a phosphorylation and release of FOXO3a protein from PUMA and GADD45a chromatin. We show here that Myc significantly and selectively contributes to repression of FOXO-mediated expression of PUMA and GADD45a. We found that in Myc deprived cells inhibition of PUMA and GADD45a following serum stimulation is impaired and that Myc does not interfere with p53 induction of PUMA transcription. We observed that following activation, Myc is rapidly recruited to PUMA and GADD45a chromatin, with a concomitant switch in promoter occupancy from FOXO3a to Myc. Myc recruitment stimulates deacetylation of Histone H3 and H4 and methylation of lysine 9 in H3 (H3K9me2) on both PUMA and GADD45 chromatin. These data highlight a Myc role on cell growth by selectively inhibiting FOXO3a induced transcription of PUMA and GADD45. PMID:21835778

  2. MYC Amplification in Angiosarcoma Arising from an Arteriovenous Graft Site

    PubMed Central

    Paral, Kristen M.; Raca, Gordana; Krausz, Thomas

    2015-01-01

    Angiosarcoma arising in association with an arteriovenous graft (AVG) or fistula is a unique clinicopathologic scenario that appears to be gaining recognition in the literature. Among reported cases, none has described high-level MYC gene amplification, a genetic aberration that is increasingly unifying the various clinicopathologic subdivisions of angiosarcoma. We therefore report the MYC gene status in a case of angiosarcoma arising at an AVG site. PMID:26682080

  3. Role of DLC1 tumor suppressor gene and MYC oncogene in pathogenesis of human hepatocellular carcinoma: Potential prospects for combined targeted therapeutics

    PubMed Central

    ZIMONJIC, DRAZEN B.; POPESCU, NICHOLAS C.

    2012-01-01

    Hepatocellular carcinoma (HCC) is the third leading cause of cancer death, and its incidence is increasing worldwide in an alarming manner. The development of curative therapy for advanced and metastatic HCC is a high clinical priority. The HCC genome is complex and heterogeneous; therefore, the identification of recurrent genomic and related gene alterations is critical for developing clinical applications for diagnosis, prognosis and targeted therapy of the disease. This article focuses on recent research progress and our contribution in identifying and deciphering the role of defined genetic alterations in the pathogenesis of HCC. A significant number of genes that promote or suppress HCC cell growth have been identified at the sites of genomic reorganization. Notwithstanding the accumulation of multiple genetic alterations, highly recurrent changes on a single chromosome can alter the expression of oncogenes and tumor suppressor genes (TSGs) whose deregulation may be sufficient to drive the progression of normal hepatocytes to malignancy. A distinct and highly recurrent pattern of genomic imbalances in HCC includes the loss of DNA copy number (associated with loss of heterozygosity) of TSG-containing chromosome 8p and gain of DNA copy number or regional amplification of protooncogenes on chromosome 8q. Even though 8p is relatively small, it carries an unusually large number of TSGs, while, on the other side, several oncogenes are dispersed along 8q. Compelling evidence demonstrates that DLC1, a potent TSG on 8p, and MYC oncogene on 8q play a critical role in the pathogenesis of human HCC. Direct evidence for their role in the genesis of HCC has been obtained in a mosaic mouse model. Knockdown of DLC1 helps MYC in the induction of hepatoblast transformation in vitro, and in the development of HCC in vivo. Therapeutic interventions, which would simultaneously target signaling pathways governing both DLC1 and MYC functions in hepatocarcinogenesis, could result in

  4. Inhibition of N-Myc down regulated gene 1 in in vitro cultured human glioblastoma cells

    PubMed Central

    Said, Harun M; Polat, Buelent; Stein, Susanne; Guckenberger, Mathias; Hagemann, Carsten; Staab, Adrian; Katzer, Astrid; Anacker, Jelena; Flentje, Michael; Vordermark, Dirk

    2012-01-01

    AIM: To study short dsRNA oligonucleotides (siRNA) as a potent tool for artificially modulating gene expression of N-Myc down regulated gene 1 (NDRG1) gene induced under different physiological conditions (Normoxia and hypoxia) modulating NDRG1 transcription, mRNA stability and translation. METHODS: A cell line established from a patient with glioblastoma multiforme. Plasmid DNA for transfections was prepared with the Endofree Plasmid Maxi kit. From plates containing 5 × 107 cells, nuclear extracts were prepared according to previous protocols. The pSUPER-NDRG1 vectors were designed, two sequences were selected from the human NDRG1 cDNA (5’-GCATTATTGGCATGGGAAC-3’ and 5’-ATGCAGAGTAACGTGGAAG-3’. reverse transcription polymerase chain reaction was performed using primers designed using published information on β-actin and hypoxia-inducible factor (HIF)-1α mRNA sequences in GenBank. NDRG1 mRNA and protein level expression results under different conditions of hypoxia or reoxygenation were compared to aerobic control conditions using the Mann-Whitney U test. Reoxygenation values were also compared to the NDRG1 levels after 24 h of hypoxia (P < 0.05 was considered significant). RESULTS: siRNA- and iodoacetate (IAA)-mediated downregulation of NDRG1 mRNA and protein expression in vitro in human glioblastoma cell lines showed a nearly complete inhibition of NDRG1 expression when compared to the results obtained due to the inhibitory role of glycolysis inhibitor IAA. Hypoxia responsive elements bound by nuclear HIF-1 in human glioblastoma cells in vitro under different oxygenation conditions and the clearly enhanced binding of nuclear extracts from glioblastoma cell samples exposed to extreme hypoxic conditions confirmed the HIF-1 Western blotting results. CONCLUSION: NDRG1 represents an additional diagnostic marker for brain tumor detection, due to the role of hypoxia in regulating this gene, and it can represent a potential target for tumor treatment in human

  5. Aurora kinase A mediates c-Myc's oncogenic effects in hepatocellular carcinoma.

    PubMed

    Lu, Longfeng; Han, Han; Tian, Yuan; Li, Wenjuan; Zhang, Jinxiang; Feng, Maohui; Li, Youjun

    2015-11-01

    Dysregulation of c-Myc (Myc) has been shown to contribute to progression of hepatocellular carcinoma, however, the detailed molecular mechanism remains poorly understood. Here, we report that Myc binds to the Aurora kinase A (Aurka) promoter and induces expression of Aurka in HCC cells. Increased expression of Aurka correlates with that of Myc in HCC. Nuclear accumulation of Aurka was confirmed by subcellular protein fractionation and immunoblot experiments in HCC cells. Myc inhibition decreases the nuclear accumulation of Aurka in HCC cells. Also Aurka accumulating in the nucleus up-regulates Myc transcription by binding the Myc promoter containing the highly conserved CCCTCCCCA in the NHE region of the CpG islands. Inhibition of Myc or Aurka diminishes the malignant phenotypes of HCC cells by down-regulating some common target genes. Also Aurka and Myc mediates the effects of each other, at least partially, on proliferation, anchorage-independent soft agar growth, and ATP production. Blocking Aurka in an orthotopic model significantly impairs tumor growth in mice. These results identify a Myc-Aurka feedback loop in which Myc and Aurka regulate expression of each other at the transcriptional level and both play an important role in hepatocarcinogenesis. PMID:25284017

  6. Recurrent CIC Gene Abnormalities in Angiosarcomas: A Molecular Study of 120 Cases With Concurrent Investigation of PLCG1, KDR, MYC, and FLT4 Gene Alterations.

    PubMed

    Huang, Shih-Chiang; Zhang, Lei; Sung, Yun-Shao; Chen, Chun-Liang; Kao, Yu-Chien; Agaram, Narasimhan P; Singer, Samuel; Tap, William D; D'Angelo, Sandra; Antonescu, Cristina R

    2016-05-01

    Angiosarcoma (AS) is a rare sarcoma subtype showing considerable clinicopathologic and genetic heterogeneity. Most radiation-induced AS show MYC gene amplifications, with a subset of cases harboring KDR, PTPRB, and PLCG1 mutations. Despite recent advances, the genetic abnormalities of most primary AS remain undefined. Whole-transcriptome sequencing was initiated in 2 index cases of primary soft tissue AS with epithelioid morphology occurring in young adults for novel gene discovery. The candidate abnormalities were validated and then screened by targeted sequencing and fluorescence in situ hybridization in a large cohort of 120 well-characterized AS cases. Findings were subsequently correlated with the status of KDR, PLCG1, MYC, and FLT4 gene abnormalities. The clinicopathologic relevance and prognostic significance of these genetic changes were analyzed by statistical methods. Concurrent CIC mutations and CIC rearrangements were identified in both index cases, with a CIC-LEUTX fusion detected in 1 case. Upon screening, an additional visceral AS in a young adult had a complex CIC rearrangement, whereas 6 others harbored only CIC mutations. All 3 CIC-rearranged AS cases lacked vasoformation and had a solid growth of round, epithelioid to rhabdoid cells, showing immunoreactivity for CD31 and Ets-related gene and sharing a transcriptional signature with other round cell sarcomas, including CIC-rearranged tumors. Overall, CIC abnormalities occurred in 9% (9/98) of cases, affecting younger patients with primary AS, with an inferior disease-free survival. In contrast, PLCG1 and KDR mutations occurred in both primary and secondary AS cases, accounting for 9.5% and 7%, respectively, with a predilection for breast and bone/viscera location, regardless of MYC status. MYC amplification was present in most secondary AS related to breast cancer (91%) compared with other causes (25%) or primary AS (7%). FLT4-amplified AS lacked PLCG1/KDR mutations, occurring predominantly in MYC

  7. Self-assembly of c-myc DNA promoted by a single enantiomer ruthenium complex as a potential nuclear targeting gene carrier.

    PubMed

    Wu, Qiong; Mei, Wenjie; Zheng, Kangdi; Ding, Yang

    2016-01-01

    Gene therapy has long been limited in the clinic, due in part to the lack of safety and efficacy of the gene carrier. Herein, a single enantiomer ruthenium(II) complex, Λ-[Ru(bpy)2(p-BEPIP)](ClO4)2 (Λ-RM0627, bpy = 4,4'-bipyridine, p-BEPIP = 2-(4-phenylacetylenephenyl)imidazole [4,5f][1, 10] phenanthroline), has been synthesized and investigated as a potential gene carrier that targets the nucleus. In this report, it is shown that Λ-RM0627 promotes self-assembly of c-myc DNA to form a nanowire structure. Further studies showed that the nano-assembly of c-myc DNA that induced Λ-RM0627 could be efficiently taken up and enriched in the nuclei of HepG2 cells. After treatment of the nano-assembly of c-myc DNA with Λ-RM0627, over-expression of c-myc in HepG2 cells was observed. In summary, Λ-RM0627 played a key role in the transfer and release of c-myc into cells, which strongly indicates Λ-RM0627 as a potent carrier of c-myc DNA that targets the nucleus of tumor cells. PMID:27381008

  8. Self-assembly of c-myc DNA promoted by a single enantiomer ruthenium complex as a potential nuclear targeting gene carrier

    PubMed Central

    Wu, Qiong; Mei, Wenjie; Zheng, Kangdi; Ding, Yang

    2016-01-01

    Gene therapy has long been limited in the clinic, due in part to the lack of safety and efficacy of the gene carrier. Herein, a single enantiomer ruthenium(II) complex, Λ-[Ru(bpy)2(p-BEPIP)](ClO4)2 (Λ-RM0627, bpy = 4,4′-bipyridine, p-BEPIP = 2-(4-phenylacetylenephenyl)imidazole [4,5f][1, 10] phenanthroline), has been synthesized and investigated as a potential gene carrier that targets the nucleus. In this report, it is shown that Λ-RM0627 promotes self-assembly of c-myc DNA to form a nanowire structure. Further studies showed that the nano-assembly of c-myc DNA that induced Λ-RM0627 could be efficiently taken up and enriched in the nuclei of HepG2 cells. After treatment of the nano-assembly of c-myc DNA with Λ-RM0627, over-expression of c-myc in HepG2 cells was observed. In summary, Λ-RM0627 played a key role in the transfer and release of c-myc into cells, which strongly indicates Λ-RM0627 as a potent carrier of c-myc DNA that targets the nucleus of tumor cells. PMID:27381008

  9. N-Myc expression enhances the oncolytic effects of vesicular stomatitis virus in human neuroblastoma cells.

    PubMed

    Corredor, Juan C; Redding, Nicole; Bloté, Karen; Robbins, Stephen M; Senger, Donna L; Bell, John C; Beaudry, Paul

    2016-01-01

    N-myc oncogene amplification is associated but not present in all cases of high-risk neuroblastoma (NB). Since oncogene expression could often modulate sensitivity to oncolytic viruses, we wanted to examine if N-myc expression status would determine virotherapy efficacy to high-risk NB. We showed that induction of exogenous N-myc in a non-N-myc-amplified cell line background (TET-21N) increased susceptibility to oncolytic vesicular stomatitis virus (mutant VSVΔM51) and alleviated the type I IFN-induced antiviral state. Cells with basal N-myc, on the other hand, were less susceptible to virus-induced oncolysis and established a robust IFN-mediated antiviral state. The same effects were also observed in NB cell lines with and without N-myc amplification. Microarray analysis showed that N-myc overexpression in TET-21N cells downregulated IFN-stimulated genes (ISGs) with known antiviral functions. Furthermore, virus infection caused significant changes in global gene expression in TET-21N cells overexpressing N-myc. Such changes involved ISGs with various functions. Therefore, the present study showed that augmented susceptibility to VSVΔM51 by N-myc at least involves downregulation of ISGs with antiviral functions and alleviation of the IFN-stimulated antiviral state. Our studies suggest the potential utility of N-myc amplification/overexpression as a predictive biomarker of virotherapy response for high-risk NB using IFN-sensitive oncolytic viruses. PMID:27626059

  10. N-Myc expression enhances the oncolytic effects of vesicular stomatitis virus in human neuroblastoma cells

    PubMed Central

    Corredor, Juan C; Redding, Nicole; Bloté, Karen; Robbins, Stephen M; Senger, Donna L; Bell, John C; Beaudry, Paul

    2016-01-01

    N-myc oncogene amplification is associated but not present in all cases of high-risk neuroblastoma (NB). Since oncogene expression could often modulate sensitivity to oncolytic viruses, we wanted to examine if N-myc expression status would determine virotherapy efficacy to high-risk NB. We showed that induction of exogenous N-myc in a non-N-myc-amplified cell line background (TET-21N) increased susceptibility to oncolytic vesicular stomatitis virus (mutant VSVΔM51) and alleviated the type I IFN-induced antiviral state. Cells with basal N-myc, on the other hand, were less susceptible to virus-induced oncolysis and established a robust IFN-mediated antiviral state. The same effects were also observed in NB cell lines with and without N-myc amplification. Microarray analysis showed that N-myc overexpression in TET-21N cells downregulated IFN-stimulated genes (ISGs) with known antiviral functions. Furthermore, virus infection caused significant changes in global gene expression in TET-21N cells overexpressing N-myc. Such changes involved ISGs with various functions. Therefore, the present study showed that augmented susceptibility to VSVΔM51 by N-myc at least involves downregulation of ISGs with antiviral functions and alleviation of the IFN-stimulated antiviral state. Our studies suggest the potential utility of N-myc amplification/overexpression as a predictive biomarker of virotherapy response for high-risk NB using IFN-sensitive oncolytic viruses. PMID:27626059

  11. Myc--what we have learned from flies.

    PubMed

    Siddall, N A; Lin, J I; Hime, G R; Quinn, L M

    2009-07-01

    The Myc family proteins are key regulators of animal growth and development. dMyc, the only Drosophila member of the Myc gene family, is orthologous to the mammalian c-Myc oncoprotein. Extensive studies have revealed much about both upstream regulators and downstream target genes in the sphere of Myc regulation. Here, we review some of the critical discoveries made using the Drosophila model, in particular those studies that have explored the essential role of the Myc family in growth and cell cycle progression and identified many of the upstream signals and downstream targets common to both c-Myc and dMyc. PMID:19601763

  12. Myc proteins as therapeutic targets

    PubMed Central

    Gustafson, WC; Weiss, WA

    2010-01-01

    Myc proteins (c-myc, Mycn and Mycl) target proliferative and apoptotic pathways vital for progression in cancer. Amplification of the MYCN gene has emerged as one of the clearest indicators of aggressive and chemotherapy-refractory disease in children with neuroblastoma, the most common extracranial solid tumor of childhood. Phosphorylation and ubiquitin-mediated modulation of Myc protein influence stability and represent potential targets for therapeutic intervention. Phosphorylation of Myc proteins is controlled in-part by the receptor tyrosine kinase/phosphatidylinositol 3-kinase/Akt/mTOR signaling, with additional contributions from Aurora A kinase. Myc proteins regulate apoptosis in part through interactions with the p53/Mdm2/Arf signaling pathway. Mutation in p53 is commonly observed in patients with relapsed neuroblastoma, contributing to both biology and therapeutic resistance. This review examines Myc function and regulation in neuroblastoma, and discusses emerging therapies that target Mycn. PMID:20101214

  13. MYC pathway activation in triple-negative breast cancer is synthetic lethal with CDK inhibition

    PubMed Central

    Horiuchi, Dai; Kusdra, Leonard; Huskey, Noelle E.; Chandriani, Sanjay; Lenburg, Marc E.; Gonzalez-Angulo, Ana Maria; Creasman, Katelyn J.; Bazarov, Alexey V.; Smyth, James W.; Davis, Sarah E.; Yaswen, Paul; Mills, Gordon B.; Esserman, Laura J.

    2012-01-01

    Estrogen, progesterone, and HER2 receptor-negative triple-negative breast cancers encompass the most clinically challenging subtype for which targeted therapeutics are lacking. We find that triple-negative tumors exhibit elevated MYC expression, as well as altered expression of MYC regulatory genes, resulting in increased activity of the MYC pathway. In primary breast tumors, MYC signaling did not predict response to neoadjuvant chemotherapy but was associated with poor prognosis. We exploit the increased MYC expression found in triple-negative breast cancers by using a synthetic-lethal approach dependent on cyclin-dependent kinase (CDK) inhibition. CDK inhibition effectively induced tumor regression in triple-negative tumor xenografts. The proapoptotic BCL-2 family member BIM is up-regulated after CDK inhibition and contributes to this synthetic-lethal mechanism. These results indicate that aggressive breast tumors with elevated MYC are uniquely sensitive to CDK inhibitors. PMID:22430491

  14. Coexistent rearrangements of c-MYC, BCL2, and BCL6 genes in a diffuse large B-cell lymphoma.

    PubMed

    Ueda, Chiyoko; Nishikori, Momoko; Kitawaki, Toshio; Uchiyama, Takashi; Ohno, Hitoshi

    2004-01-01

    We present a patient with stage III de novo diffuse large B-cell lymphoma. The lymphoma cells showed mature B-cell immunophenotype but lacked surface immunoglobulin (Ig) expression. Long-distance and long-distance inverse polymerase chain reaction assays to detect the oncogene/Ig gene rearrangement revealed that the cells carried 3 independent fusion genes, namely, c-MYC/Ig heavy chain gene (IgH), BCL2/IgH, and Ig lambda light chain gene/BCL6. Thus, the lymphoma cells concurrently carried t(8;14)(q24;q32), t(14;18)(q32;q21), and t(3;22)(q27;q11), which developed in association with class switching, V/D/J recombination, and somatic hypermutation, respectively. The lymphoma responded to chemoradiotherapy, and the patient has been well for 2 years, suggesting that multiple oncogene rearrangements may not necessarily be associated with poor clinical outcome. PMID:14979479

  15. c-myc copy number gains in bladder cancer detected by fluorescence in situ hybridization.

    PubMed Central

    Sauter, G.; Carroll, P.; Moch, H.; Kallioniemi, A.; Kerschmann, R.; Narayan, P.; Mihatsch, M. J.; Waldman, F. M.

    1995-01-01

    Amplification and overexpression of c-myc have been suggested as prognostic markers in human cancer. To assess the role of c-myc gene copy number alterations in bladder cancer, 87 bladder tumors were examined for c-myc aberrations by fluorescence in situ hybridization. Dual labeling hybridization with a repetitive pericentromeric probe specific for chromosome 8 and a probe for the c-myc locus (at 8q24) was performed to analyze c-myc copy number in relation to chromosome 8 copy number on a cell by cell basis. A clear-cut c-myc amplification (up to 40 to 150 copies per cell) was found in 3 tumors. There was a low level c-myc copy number increase in 32 of the remaining 84 tumors. There was no association of low level c-myc copy number increase with c-myc protein overexpression. This suggests that a c-myc gene copy number gain as detected by fluorescence in situ hybridization does not necessarily reflect a disturbed c-myc gene function but may indicate a structural chromosome 8 abnormality including gain of distal 8q. The strong association of low level c-myc (8q) gains with tumor grade (P < 0.0001), stage (P < 0.0001), chromosome polysomy (P < 0.0001), p53 protein expression (P = 0.0019), p53 deletion (P = 0.0403), and tumor cell proliferation (Ki67 labeling index; P = 0.0021) is consistent with a role of chromosome 8 alterations in bladder cancer progression. Images Figure 1 PMID:7747807

  16. Growth inhibition and apoptosis induced by daunomycin-conjugated triplex-forming oligonucleotides targeting the c-myc gene in prostate cancer cells

    PubMed Central

    Napoli, Sara; Negri, Umberto; Arcamone, Federico; Capobianco, Massimo L.; Carbone, Giuseppina M.; Catapano, Carlo V.

    2006-01-01

    Covalent attachment of intercalating agents to triplex-forming oligonucleotides (TFOs) is a promising strategy to enhance triplex stability and biological activity. We have explored the possibility to use the anticancer drug daunomycin as triplex stabilizing agent. Daunomycin-conjugated TFOs (dauno-TFOs) bind with high affinity and maintain the sequence-specificity required for targeting individual genes in the human genome. Here, we examined the effects of two dauno-TFOs targeting the c-myc gene on gene expression, cell proliferation and survival. The dauno-TFOs were directed to sequences immediately upstream (dauno-GT11A) and downstream (dauno-GT11B) the major transcriptional start site in the c-myc gene. Both dauno-TFOs were able to down-regulate promoter activity and transcription of the endogenous gene. Myc-targeted dauno-TFOs inhibited growth and induced apoptosis of prostate cancer cells constitutively expressing the gene. Daunomycin-conjugated control oligonucleotides with similar sequences had only minimal effects, confirming that the activity of dauno-TFOs was sequence-specific and triplex-mediated. To test the selectivity of dauno-TFOs, we examined their effects on growth of normal human fibroblasts, which express low levels of c-myc. Despite their ability to inhibit c-myc transcription, both dauno-TFOs failed to inhibit growth of normal fibroblasts at concentrations that inhibited growth of prostate cancer cells. In contrast, daunomycin inhibited equally fibroblasts and prostate cancer cells. Thus, daunomycin per se did not contribute to the antiproliferative activity of dauno-TFOs, although it greatly enhanced their ability to form stable triplexes at the target sites and down-regulate c-myc. Our data indicate that dauno-TFOs are attractive gene-targeting agents for development of new cancer therapeutics. PMID:16449206

  17. Arabidopsis Basic Helix-Loop-Helix Transcription Factors MYC2, MYC3, and MYC4 Regulate Glucosinolate Biosynthesis, Insect Performance, and Feeding Behavior[W][OPEN

    PubMed Central

    Schweizer, Fabian; Fernández-Calvo, Patricia; Zander, Mark; Diez-Diaz, Monica; Fonseca, Sandra; Glauser, Gaétan; Lewsey, Mathew G.; Ecker, Joseph R.; Solano, Roberto; Reymond, Philippe

    2013-01-01

    Arabidopsis thaliana plants fend off insect attack by constitutive and inducible production of toxic metabolites, such as glucosinolates (GSs). A triple mutant lacking MYC2, MYC3, and MYC4, three basic helix-loop-helix transcription factors that are known to additively control jasmonate-related defense responses, was shown to have a highly reduced expression of GS biosynthesis genes. The myc2 myc3 myc4 (myc234) triple mutant was almost completely devoid of GS and was extremely susceptible to the generalist herbivore Spodoptera littoralis. On the contrary, the specialist Pieris brassicae was unaffected by the presence of GS and preferred to feed on wild-type plants. In addition, lack of GS in myc234 drastically modified S. littoralis feeding behavior. Surprisingly, the expression of MYB factors known to regulate GS biosynthesis genes was not altered in myc234, suggesting that MYC2/MYC3/MYC4 are necessary for direct transcriptional activation of GS biosynthesis genes. To support this, chromatin immunoprecipitation analysis showed that MYC2 binds directly to the promoter of several GS biosynthesis genes in vivo. Furthermore, yeast two-hybrid and pull-down experiments indicated that MYC2/MYC3/MYC4 interact directly with GS-related MYBs. This specific MYC–MYB interaction plays a crucial role in the regulation of defense secondary metabolite production and underlines the importance of GS in shaping plant interactions with adapted and nonadapted herbivores. PMID:23943862

  18. Regulation of CDKN2B expression by interaction of Arnt with Miz-1 - a basis for functional integration between the HIF and Myc gene regulatory pathways

    PubMed Central

    2014-01-01

    Background Hypoxia- and Myc-dependent transcriptional regulatory pathways are frequently deregulated in cancer cells. These pathways converge in many cellular responses, but the underlying molecular mechanisms are unclear. Methods The ability of Miz-1 and Arnt to interact was identified in a yeast two-hybrid screen. The mode of interaction and the functional consequences of complex formation were analyzed by diverse molecular biology methods, in vitro. Statistical analyses were performed by Student’s t-test and ANOVA. Results In the present study we demonstrate that the aryl hydrocarbon receptor nuclear translocator (Arnt), which is central in hypoxia-induced signaling, forms a complex with Miz-1, an important transcriptional regulator in Myc-mediated transcriptional repression. Overexpression of Arnt induced reporter gene activity driven by the proximal promoter of the cyclin-dependent kinase inhibitor 2B gene (CDKN2B), which is an established target for the Myc/Miz-1 complex. In contrast, mutated forms of Arnt, that were unable to interact with Miz-1, had reduced capability to activate transcription. Moreover, repression of Arnt reduced endogenous CDKN2B expression, and chromatin immunoprecipitation demonstrated that Arnt interacts with the CDKN2B promoter. The transcriptional activity of Arnt was counteracted by Myc, but not by a mutated variant of Myc that is unable to interact with Miz-1, suggesting mutually exclusive interaction of Arnt and Myc with Miz-1. Our results also establish CDKN2B as a hypoxia regulated gene, as endogenous CDKN2B mRNA and protein levels were reduced by hypoxic treatment of U2OS cells. Conclusions Our data reveal a novel mode of regulation by protein-protein interaction that directly ties together, at the transcriptional level, the Myc- and hypoxia-dependent signaling pathways and expands our understanding of the roles of hypoxia and cell cycle alterations during tumorigenesis. PMID:24618291

  19. Amplification and expression of the c-myc oncogene in human lung cancer cell lines.

    PubMed

    Little, C D; Nau, M M; Carney, D N; Gazdar, A F; Minna, J D

    Genetic changes involving the c-myc oncogene have been observed in human tumours. In particular, the c-myc gene is translocated in Burkitt's lymphoma and is amplified in the human promyelocytic leukaemia cell line, HL-60, which contains double minute chromosomes (DMs). More recently, an amplified c-myc gene has been positioned on a chromosomal homogeneous staining region (HSR) in a human colon cancer cell line, COLO 320, with neuroendocrine properties. Furthermore, c-myc is expressed in increased amounts in some human tumour lines, and in some cases, human small cell lung cancers (SCLC) contain DMs and HSRs. These findings prompted us to study the c-myc gene and its RNA expression in a series of human lung cancer cell lines. We now report amplification and expression of the c-myc oncogene in a system other than B-cell lymphomas, namely human lung cancer. Of 18 human lung cancer cell lines tested, 8 showed an amplified 12.5-kilobase (kb) EcoRI c-myc DNA band. Of particular interest are five SCLC lines with a high degree of c-myc DNA amplification (20-76-fold) and greatly increased levels of c-myc RNA. All five lines reside in the variant class of SCLC (SCLC-V) characterized by altered morphology, lack of expression of some SCLC-differentiated functions and more malignant behaviour than pure SCLC. Three of the five lines which have been karyotyped also contain DMs or HSRs. The finding of a greatly amplified c-myc gene in all cell lines of the SCLC-V class examined strongly suggests a role for the c-myc gene in the phenotypic conversion and malignant behaviour of human lung cancer. PMID:6646201

  20. Lymphomas that recur after MYC suppression continue to exhibit oncogene addiction

    PubMed Central

    Choi, Peter S.; van Riggelen, Jan; Gentles, Andrew J.; Bachireddy, Pavan; Rakhra, Kavya; Adam, Stacey J.; Plevritis, Sylvia K.; Felsher, Dean W.

    2011-01-01

    The suppression of oncogenic levels of MYC is sufficient to induce sustained tumor regression associated with proliferative arrest, differentiation, cellular senescence, and/or apoptosis, a phenomenon known as oncogene addiction. However, after prolonged inactivation of MYC in a conditional transgenic mouse model of Eμ-tTA/tetO-MYC T-cell acute lymphoblastic leukemia, some of the tumors recur, recapitulating what is frequently observed in human tumors in response to targeted therapies. Here we report that these recurring lymphomas express either transgenic or endogenous Myc, albeit in many cases at levels below those in the original tumor, suggesting that tumors continue to be addicted to MYC. Many of the recurring lymphomas (76%) harbored mutations in the tetracycline transactivator, resulting in expression of the MYC transgene even in the presence of doxycycline. Some of the remaining recurring tumors expressed high levels of endogenous Myc, which was associated with a genomic rearrangement of the endogenous Myc locus or activation of Notch1. By gene expression profiling, we confirmed that the primary and recurring tumors have highly similar transcriptomes. Importantly, shRNA-mediated suppression of the high levels of MYC in recurring tumors elicited both suppression of proliferation and increased apoptosis, confirming that these tumors remain oncogene addicted. These results suggest that tumors induced by MYC remain addicted to overexpression of this oncogene. PMID:21969595

  1. Constitutive expression of exogenous myc in myelomonocytic cells: acquisition of a more transformed phenotype and inhibition of differentiation induction.

    PubMed

    Chisholm, O; Stapleton, P; Symonds, G

    1992-09-01

    The effects of deregulated expression of the human c-myc and MC29 v-myc oncogenes have been examined in a murine myelomonocytic cell line J774 (c-myc) and in a variety of myelomonocytic cell lines of different degrees of maturity generated from primary hematopoietic tissue (v-myc). Introduction of a Moloney murine leukemia virus long terminal repeat (LTR) c-myc construct into J774 cells resulted in constitutive expression of the exogenous myc gene and a concomitant increase in the degree of transformation and tumorigenicity of the cells. In addition, constitutive expression of exogenous myc inhibited induced differentiation of these cells by a variety of treatments including addition to the medium of lipopolysaccharide (LPS) or the phorbol ester 12-O-tetradecanoyl phorbol 13-acetate (TPA) as well as complete withdrawal of serum from the medium. The degree of increased transformation, tumorigenicity and inhibition of terminal differentiation was dependent upon the level of exogenous myc expression. For the v-myc-generated myelomonocytic cell lines, introduction of v-myc resulted in a high degree of transformation and, irrespective of the differentiation status of the cells, a block of induced differentiation. These results indicate that the level of constitutive myc expression can affect the transformed phenotype, tumorigenicity and differentiation inducibility of myelomonocytic cells. PMID:1501891

  2. PIAS1 Promotes Lymphomagenesis Through MYC Upregulation

    PubMed Central

    Rabellino, Andrea; Melegari, Margherita; Tompkins, Van S.; Chen, Weina; Van Ness, Brian G.; Teruya-Feldstein, Julie; Conacci-Sorrell, Maralice; Janz, Siegfried; Scaglioni, Pier Paolo

    2016-01-01

    Summary The MYC proto-oncogene is a transcription factor implicated in a broad range of cancers. MYC is regulated by several post-translational modifications including SUMOylation, but the functional impact of this post-translational modification is still unclear. Here we report that the SUMO E3 ligase PIAS1 SUMOylates MYC. We demonstrate that PIAS1 promotes, in a SUMOylation-dependent manner, MYC phosphorylation at serine 62 and dephosphorylation at threonine 58. These events reduce the MYC turnover leading to increased transcriptional activity. Furthermore, we find that MYC is SUMOylated in primary B-cell lymphomas and that PIAS1 is required for the viability of MYC-dependent B-cell lymphoma cells as well as several cancer cell lines of epithelial origin. Finally, Pias1 null mice display endothelial defects reminiscent of Myc null mice. Taken together these results indicate that PIAS1 is a positive regulator of MYC. PMID:27239040

  3. Enigmatic MYC Conducts an Unfolding Systems Biology Symphony.

    PubMed

    Dang, Chi V

    2010-06-01

    The enigmatic MYC oncogene, which participates broadly in cancers, revealed itself recently as the maestro of an unfolding symphony of cell growth, proliferation, death, and metabolism. The study of MYC is arguably most challenging to its students but at the same time exhilarating when MYC reveals its deeply held secrets. It is the excitement of our richer understanding of MYC that is captured in each review of this special issue of Genes & Cancer. Collectively, our deeper understanding of MYC reveals that it is a symphony conductor, controlling a large orchestra of target genes. Although MYC controls many orchestra sections, which are necessary but not sufficient for Myc function, ribosome biogenesis stands out to reveal Myc's primordial function particularly in fruit flies. Because ribosome biogenesis and the associated translational machinery are bioenergetically demanding, Myc's other target genes involved in energy metabolism must be coupled with energy demand to ensure that cells can replicate their genome and produce daughter cells. Normal cells have feedback loops that diminish MYC expression when nutrients are scarce. On the other hand, when deregulated Myc transforms cells, their constitutive bioenergetic demand can trigger cell death when energy is unavailable. This special issue captures the unfolding symphony of MYC-mediated tumorigenesis through reviews that span from a timeline of MYC research, fundamental understanding of how the MYC gene itself is regulated, the study of Myc in model organisms, Myc function, and target genes to translational research in search of new therapeutic modalities for the treatment of cancer. PMID:21218193

  4. c-MYC Generates Repair Errors via Increased Transcription of Alternative-NHEJ Factors, LIG3 and PARP1, in Tyrosine Kinase-activated Leukemias

    PubMed Central

    Muvarak, Nidal; Kelley, Shannon; Robert, Carine; Baer, Maria R.; Perrotti, Danilo; Gambacorti-Passerini, Carlo; Civin, Curt; Scheibner, Kara; Rassool, Feyruz

    2015-01-01

    Leukemias expressing the constitutively activated tyrosine kinases (TKs) BCR-ABL1 and FLT3/ITD activate signaling pathways that increase genomic instability through generation of reactive oxygen species (ROS), DNA double-strand breaks (DSBs) and error-prone repair. The non-homologous 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 poly (ADP-ribose) polymerase (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 (CML) 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 leads to genomic instability via augmented expression of ALT-NHEJ repair factors that generate repair errors. PMID:25828893

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

    SciTech Connect

    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. Cellular MYCro Economics: Balancing MYC Function with MYC Expression

    PubMed Central

    Levens, David

    2013-01-01

    The expression levels of the MYC oncoprotein have long been recognized to be associated with the outputs of major cellular processes including proliferation, cell growth, apoptosis, differentiation, and metabolism. Therefore, to understand how MYC operates, it is important to define quantitatively the relationship between MYC input and expression output for its targets as well as the higher-order relationships between the expression levels of subnetwork components and the flow of information and materials through those networks. Two different views of MYC are considered, first as a molecular microeconomic manager orchestrating specific positive and negative responses at individual promoters in collaboration with other transcription and chromatin components, and second, as a macroeconomic czar imposing an overarching rule onto all active genes. In either case, c-myc promoter output requires multiple inputs and exploits diverse mechanisms to tune expression to the appropriate levels relative to the thresholds of expression that separate health and disease. PMID:24186489

  7. Participation of cyclin A in Myc-induced apoptosis.

    PubMed Central

    Hoang, A T; Cohen, K J; Barrett, J F; Bergstrom, D A; Dang, C V

    1994-01-01

    The involvement of c-Myc in cellular proliferation or apoptosis has been linked to differential cyclin gene expression. We observed that in both proliferating cells and cells undergoing apoptosis, cyclin A (but not B, C, D1, and E) mRNA level was elevated in unsynchronized Myc-overexpressing cells when compared with parental Rat1a fibroblasts. We further demonstrated that Zn(2+)-inducible cyclin A expression was sufficient to cause apoptosis. When Myc-induced apoptosis was blocked by coexpression of Bcl-2, the levels of cyclin C, D1, and E mRNAs were also elevated. Thus, while apoptosis induced by c-Myc is associated with an elevated cyclin A mRNA level, protection from apoptosis by coexpressed Bcl-2 is associated with a complementary increase in cyclin C, D1, and E mRNAs. Images PMID:8041712

  8. Mutations in NEK8 link multiple organ dysplasia with altered Hippo signalling and increased c-MYC expression.

    PubMed

    Frank, Valeska; Habbig, Sandra; Bartram, Malte P; Eisenberger, Tobias; Veenstra-Knol, Hermine E; Decker, Christian; Boorsma, Reinder A C; Göbel, Heike; Nürnberg, Gudrun; Griessmann, Anabel; Franke, Mareike; Borgal, Lori; Kohli, Priyanka; Völker, Linus A; Dötsch, Jörg; Nürnberg, Peter; Benzing, Thomas; Bolz, Hanno J; Johnson, Colin; Gerkes, Erica H; Schermer, Bernhard; Bergmann, Carsten

    2013-06-01

    Mutations affecting the integrity and function of cilia have been identified in various genes over the last decade accounting for a group of diseases called ciliopathies. Ciliopathies display a broad spectrum of phenotypes ranging from mild manifestations to lethal combinations of multiple severe symptoms and most of them share cystic kidneys as a common feature. Our starting point was a consanguineous pedigree with three affected fetuses showing an early embryonic phenotype with enlarged cystic kidneys, liver and pancreas and developmental heart disease. By genome-wide linkage analysis, we mapped the disease locus to chromosome 17q11 and identified a homozygous nonsense mutation in NEK8/NPHP9 that encodes a kinase involved in ciliary dynamics and cell cycle progression. Missense mutations in NEK8/NPHP9 have been identified in juvenile cystic kidney jck mice and in patients suffering from nephronophthisis (NPH), an autosomal-recessive cystic kidney disease. This work confirmed a complete loss of NEK8 expression in the affected fetuses due to nonsense-mediated decay. In cultured fibroblasts derived from these fetuses, the expression of prominent polycystic kidney disease genes (PKD1 and PKD2) was decreased, whereas the oncogene c-MYC was upregulated, providing potential explanations for the observed renal phenotype. We furthermore linked NEK8 with NPHP3, another NPH protein known to cause a very similar phenotype in case of null mutations. Both proteins interact and activate the Hippo effector TAZ. Taken together, our study demonstrates that NEK8 is essential for organ development and that the complete loss of NEK8 perturbs multiple signalling pathways resulting in a severe early embryonic phenotype. PMID:23418306

  9. An ABA-increased interaction of the PYL6 ABA receptor with MYC2 Transcription Factor: A putative link of ABA and JA signaling.

    PubMed

    Aleman, Fernando; Yazaki, Junshi; Lee, Melissa; Takahashi, Yohei; Kim, Alice Y; Li, Zixing; Kinoshita, Toshinori; Ecker, Joseph R; Schroeder, Julian I

    2016-01-01

    Abscisic acid (ABA) is a plant hormone that mediates abiotic stress tolerance and regulates growth and development. ABA binds to members of the PYL/RCAR ABA receptor family that initiate signal transduction inhibiting type 2C protein phosphatases. Although crosstalk between ABA and the hormone Jasmonic Acid (JA) has been shown, the molecular entities that mediate this interaction have yet to be fully elucidated. We report a link between ABA and JA signaling through a direct interaction of the ABA receptor PYL6 (RCAR9) with the basic helix-loop-helix transcription factor MYC2. PYL6 and MYC2 interact in yeast two hybrid assays and the interaction is enhanced in the presence of ABA. PYL6 and MYC2 interact in planta based on bimolecular fluorescence complementation and co-immunoprecipitation of the proteins. Furthermore, PYL6 was able to modify transcription driven by MYC2 using JAZ6 and JAZ8 DNA promoter elements in yeast one hybrid assays. Finally, pyl6 T-DNA mutant plants show an increased sensitivity to the addition of JA along with ABA in cotyledon expansion experiments. Overall, the present study identifies a direct mechanism for transcriptional modulation mediated by an ABA receptor different from the core ABA signaling pathway, and a putative mechanistic link connecting ABA and JA signaling pathways. PMID:27357749

  10. An ABA-increased interaction of the PYL6 ABA receptor with MYC2 Transcription Factor: A putative link of ABA and JA signaling

    PubMed Central

    Aleman, Fernando; Yazaki, Junshi; Lee, Melissa; Takahashi, Yohei; Kim, Alice Y.; Li, Zixing; Kinoshita, Toshinori; Ecker, Joseph R.; Schroeder, Julian I.

    2016-01-01

    Abscisic acid (ABA) is a plant hormone that mediates abiotic stress tolerance and regulates growth and development. ABA binds to members of the PYL/RCAR ABA receptor family that initiate signal transduction inhibiting type 2C protein phosphatases. Although crosstalk between ABA and the hormone Jasmonic Acid (JA) has been shown, the molecular entities that mediate this interaction have yet to be fully elucidated. We report a link between ABA and JA signaling through a direct interaction of the ABA receptor PYL6 (RCAR9) with the basic helix-loop-helix transcription factor MYC2. PYL6 and MYC2 interact in yeast two hybrid assays and the interaction is enhanced in the presence of ABA. PYL6 and MYC2 interact in planta based on bimolecular fluorescence complementation and co-immunoprecipitation of the proteins. Furthermore, PYL6 was able to modify transcription driven by MYC2 using JAZ6 and JAZ8 DNA promoter elements in yeast one hybrid assays. Finally, pyl6 T-DNA mutant plants show an increased sensitivity to the addition of JA along with ABA in cotyledon expansion experiments. Overall, the present study identifies a direct mechanism for transcriptional modulation mediated by an ABA receptor different from the core ABA signaling pathway, and a putative mechanistic link connecting ABA and JA signaling pathways. PMID:27357749

  11. C-Myc regulates substrate oxidation patterns during early pressure-overload hypertrophy

    SciTech Connect

    Ledee, Dolena R.; Smith, Lincoln; Kajimoto, Masaki; Bruce, Margaret; Isern, Nancy G.; Xu, Chun; Portman, Michael A.; Olson, Aaron

    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.

  12. Inverse Relationship between Progesterone Receptor and Myc in Endometrial Cancer

    PubMed Central

    Dai, Donghai; Meng, Xiangbing; Thiel, Kristina W.; Leslie, Kimberly K.; Yang, Shujie

    2016-01-01

    Endometrial cancer, the most common gynecologic malignancy, is a hormonally-regulated disease. Response to progestin therapy positively correlates with hormone receptor expression, in particular progesterone receptor (PR). However, many advanced tumors lose PR expression. We recently reported that the efficacy of progestin therapy can be significantly enhanced by combining progestin with epigenetic modulators, which we term “molecularly enhanced progestin therapy.” What remained unclear was the mechanism of action and if estrogen receptor α (ERα), the principle inducer of PR, is necessary to restore functional expression of PR via molecularly enhanced progestin therapy. Therefore, we modeled advanced endometrial tumors that have lost both ERα and PR expression by generating ERα-null endometrial cancer cell lines. CRISPR-Cas9 technology was used to delete ERα at the genomic level. Our data demonstrate that treatment with a histone deacetylase inhibitor (HDACi) was sufficient to restore functional PR expression, even in cells devoid of ERα. Our studies also revealed that HDACi treatment results in marked downregulation of the oncogene Myc. We established that PR is a negative transcriptional regulator of Myc in endometrial cancer in the presence or absence of ERα, which is in contrast to studies in breast cancer cells. First, estrogen stimulation augmented PR expression and decreased Myc in endometrial cancer cell lines. Second, progesterone increased PR activity yet blunted Myc mRNA and protein expression. Finally, overexpression of PR by adenoviral transduction in ERα-null endometrial cancer cells significantly decreased expression of Myc and Myc-regulated genes. Analysis of the Cancer Genome Atlas (TCGA) database of endometrial tumors identified an inverse correlation between PR and Myc mRNA levels, with a corresponding inverse correlation between PR and Myc downstream transcriptional targets SRD5A1, CDK2 and CCNB1. Together, these data reveal a

  13. KSHV Latency Locus Cooperates with Myc to Drive Lymphoma in Mice

    PubMed Central

    Sin, Sang-Hoon; Kim, Yongbaek; Eason, Anthony; Dittmer, Dirk P.

    2015-01-01

    Kaposi sarcoma-associated herpesvirus (KSHV) has been linked to Kaposi sarcoma and B-cell malignancies. Mechanisms of KSHV-induced oncogenesis remain elusive, however, in part due to lack of reliable in vivo models. Recently, we showed that transgenic mice expressing the KSHV latent genes, including all viral microRNAs, developed splenic B cell hyperplasia with 100% penetrance, but only a fraction converted to B cell lymphomas, suggesting that cooperative oncogenic events were missing. Myc was chosen as a possible candidate, because Myc is deregulated in many B cell lymphomas. We crossed KSHV latency locus transgenic (latency) mice to Cα Myc transgenic (Myc) mice. By itself these Myc transgenic mice develop lymphomas only rarely. In the double transgenic mice (Myc/latency) we observed plasmacytosis, severe extramedullary hematopoiesis in spleen and liver, and increased proliferation of splenocytes. Myc/latency mice developed frank lymphoma at a higher rate than single transgenic latency or Myc mice. These data indicate that the KSHV latency locus cooperates with the deregulated Myc pathways to further lymphoma progression. PMID:26327622

  14. Taking on challenging targets: making MYC druggable.

    PubMed

    Horiuchi, Dai; Anderton, Brittany; Goga, Andrei

    2014-01-01

    The transcription factor proto-oncogene c-MYC (hereafter MYC) was first identified more than 3 decades ago and has since been found deregulated in a wide variety of the most aggressive human malignancies. As a pleiotropic transcription factor, MYC directly or indirectly controls expression of hundreds of coding and noncoding genes, which affect cell cycle entry, proliferation, differentiation, metabolism, and death/survival decisions of normal and cancer cells. Tumors with elevated MYC expression often exhibit highly proliferative, aggressive phenotypes, and elevated MYC expression has been correlated with diminished disease-free survival for a variety of human cancers. The use of MYC overexpression or MYC-dependent transcriptional gene signatures as clinical biomarkers is currently being investigated. Furthermore, preclinical animal and cell-based model systems have been extensively utilized in an effort to uncover the mechanisms of MYC-dependent tumorigenesis and tumor maintenance. Despite our ever-growing understanding of MYC biology, currently no targeted therapeutic strategy is clinically available to treat tumors that have acquired elevated MYC expression. This article summarizes the progresses being made to discover and implement new therapies to kill MYC over-expressing tumors-a target that was once deemed undruggable. PMID:24857145

  15. The MYC 3' Wnt-Responsive Element Drives Oncogenic MYC Expression in Human Colorectal Cancer Cells.

    PubMed

    Rennoll, Sherri A; Eshelman, Melanie A; Raup-Konsavage, Wesley M; Kawasawa, Yuka Imamura; Yochum, Gregory S

    2016-01-01

    Mutations in components of the Wnt/β-catenin signaling pathway drive colorectal cancer (CRC) by deregulating expression of downstream target genes including the c-MYC proto-oncogene (MYC). The critical regulatory DNA enhancer elements that control oncogenic MYC expression in CRC have yet to be fully elucidated. In previous reports, we correlated T-cell factor (TCF) and β-catenin binding to the MYC 3' Wnt responsive DNA element (MYC 3' WRE) with MYC expression in HCT116 cells. Here we used CRISPR/Cas9 to determine whether this element is a critical driver of MYC. We isolated a clonal population of cells that contained a deletion of a single TCF binding element (TBE) within the MYC 3' WRE. This deletion reduced TCF/β-catenin binding to this regulatory element and decreased MYC expression. Using RNA-Seq analysis, we found altered expression of genes that regulate metabolic processes, many of which are known MYC target genes. We found that 3' WRE-Mut cells displayed a reduced proliferative capacity, diminished clonogenic growth, and a decreased potential to form tumors in vivo. These findings indicate that the MYC 3' WRE is a critical driver of oncogenic MYC expression and suggest that this element may serve as a therapeutic target for CRC. PMID:27223305

  16. Nickel compounds induce apoptosis in human bronchial epithelial Beas-2B cells by activation of c-Myc through ERK pathway

    SciTech Connect

    Li Qin; Suen, T.-C.; Sun Hong; Arita, Adriana; Costa, Max

    2009-03-01

    Nickel compounds are carcinogenic to humans and have been shown to alter epigenetic homeostasis. The c-Myc protein controls 15% of human genes and it has been shown that fluctuations of c-Myc protein alter global epigenetic marks. Therefore, the regulation of c-Myc by nickel ions in immortalized but not tumorigenic human bronchial epithelial Beas-2B cells was examined in this study. It was found that c-Myc protein expression was increased by nickel ions in non-tumorigenic Beas-2B and human keratinocyte HaCaT cells. The results also indicated that nickel ions induced apoptosis in Beas-2B cells. Knockout of c-Myc and its restoration in a rat cell system confirmed the essential role of c-Myc in nickel ion-induced apoptosis. Further studies in Beas-2B cells showed that nickel ion increased the c-Myc mRNA level and c-Myc promoter activity, but did not increase c-Myc mRNA and protein stability. Moreover, nickel ion upregulated c-Myc in Beas-2B cells through the MEK/ERK pathway. Collectively, the results demonstrate that c-Myc induction by nickel ions occurs via an ERK-dependent pathway and plays a crucial role in nickel-induced apoptosis in Beas-2B cells.

  17. Gene Therapy of c-myc Suppressor FUSE-Binding Protein-Interacting Repressor by Sendai Virus Delivery Prevents Tracheal Stenosis

    PubMed Central

    Mizokami, Daisuke; Araki, Koji; Tanaka, Nobuaki; Suzuki, Hiroshi; Tomifuji, Masayuki; Yamashita, Taku; Ueda, Yasuji; Shimada, Hideaki; Matsushita, Kazuyuki; Shiotani, Akihiro

    2015-01-01

    Acquired tracheal stenosis remains a challenging problem for otolaryngologists. The objective of this study was to determine whether the Sendai virus (SeV)-mediated c-myc suppressor, a far upstream element (FUSE)-binding protein (FBP)-interacting repressor (FIR), modulates wound healing of the airway mucosa, and whether it prevents tracheal stenosis in an animal model of induced mucosal injury. A fusion gene-deleted, non-transmissible SeV vector encoding FIR (FIR-SeV/ΔF) was prepared. Rats with scraped airway mucosae were administered FIR-SeV/ΔF through the tracheostoma. The pathological changes in the airway mucosa and in the tracheal lumen were assessed five days after scraping. Untreated animals showed hyperplasia of the airway epithelium and a thickened submucosal layer with extensive fibrosis, angiogenesis, and collagen deposition causing lumen stenosis. By contrast, the administration of FIR-SeV/ΔF decreased the degree of tracheal stenosis (P < 0.05) and improved the survival rate (P < 0.05). Immunohistochemical staining showed that c-Myc expression was downregulated in the tracheal basal cells of the FIR-SeV/ΔF-treated animals, suggesting that c-myc was suppressed by FIR-SeV/ΔF in the regenerating airway epithelium of the injured tracheal mucosa. The airway-targeted gene therapy of the c-myc suppressor FIR, using a recombinant SeV vector, prevented tracheal stenosis in a rat model of airway mucosal injury. PMID:25569246

  18. Inhibition of fatty acid oxidation as a therapy for MYC-overexpressing triple-negative breast cancer.

    PubMed

    Camarda, Roman; Zhou, Alicia Y; Kohnz, Rebecca A; Balakrishnan, Sanjeev; Mahieu, Celine; Anderton, Brittany; Eyob, Henok; Kajimura, Shingo; Tward, Aaron; Krings, Gregor; Nomura, Daniel K; Goga, Andrei

    2016-04-01

    Expression of the oncogenic transcription factor MYC is disproportionately elevated in triple-negative breast cancer (TNBC), as compared to estrogen receptor-, progesterone receptor- or human epidermal growth factor 2 receptor-positive (RP) breast cancer. We and others have shown that MYC alters metabolism during tumorigenesis. However, the role of MYC in TNBC metabolism remains mostly unexplored. We hypothesized that MYC-dependent metabolic dysregulation is essential for the growth of MYC-overexpressing TNBC cells and may identify new therapeutic targets for this clinically challenging subset of breast cancer. Using a targeted metabolomics approach, we identified fatty acid oxidation (FAO) intermediates as being dramatically upregulated in a MYC-driven model of TNBC. We also identified a lipid metabolism gene signature in patients with TNBC that were identified from The Cancer Genome Atlas database and from multiple other clinical data sets, implicating FAO as a dysregulated pathway that is critical for TNBC cell metabolism. We found that pharmacologic inhibition of FAO catastrophically decreased energy metabolism in MYC-overexpressing TNBC cells and blocked tumor growth in a MYC-driven transgenic TNBC model and in a MYC-overexpressing TNBC patient-derived xenograft. These findings demonstrate that MYC-overexpressing TNBC shows an increased bioenergetic reliance on FAO and identify the inhibition of FAO as a potential therapeutic strategy for this subset of breast cancer. PMID:26950360

  19. MYC and Prostate Cancer

    PubMed Central

    Koh, Cheryl M.; Bieberich, Charles J.; Dang, Chi V.; Nelson, William G.; Yegnasubramanian, Srinivasan; De Marzo, Angelo M.

    2010-01-01

    Prostate cancer, the majority of which is adenocarcinoma, is the most common epithelial cancer affecting a majority of elderly men in Western nations. Its manifestation, however, varies from clinically asymptomatic insidious neoplasms that progress slowly and do not threaten life to one that is highly aggressive with a propensity for metastatic spread and lethality if not treated in time. A number of somatic genetic and epigenetic alterations occur in prostate cancer cells. Some of these changes, such as loss of the tumor suppressors PTEN and p53, are linked to disease progression. Others, such as ETS gene fusions, appear to be linked more with early phases of the disease, such as invasion. Alterations in chromosome 8q24 in the region of MYC have also been linked to disease aggressiveness for many years. However, a number of recent studies in human tissues have indicated that MYC appears to be activated at the earliest phases of prostate cancer (e.g., in tumor-initiating cells) in prostatic intraepithelial neoplasia, a key precursor lesion to invasive prostatic adenocarcinoma. The initiation and early progression of prostate cancer can be recapitulated in genetically engineered mouse models, permitting a richer understanding of the cause and effects of loss of tumor suppressors and activation of MYC. The combination of studies using human tissues and mouse models paints an emerging molecular picture of prostate cancer development and early progression. This picture reveals that MYC contributes to disease initiation and progression by stimulating an embryonic stem cell–like signature characterized by an enrichment of genes involved in ribosome biogenesis and by repressing differentiation. These insights pave the way to potential novel therapeutic concepts based on MYC biology. PMID:21779461

  20. Runx transcription factors repress human and murine c-Myc expression in a DNA-binding and C-terminally dependent manner.

    PubMed

    Jacobs, Paejonette T; Cao, Li; Samon, Jeremy B; Kane, Christyne A; Hedblom, Emmett E; Bowcock, Anne; Telfer, Janice C

    2013-01-01

    The transcription factors Runx1 and c-Myc have individually been shown to regulate important gene targets as well as to collaborate in oncogenesis. However, it is unknown whether there is a regulatory relationship between the two genes. In this study, we investigated the transcriptional regulation of endogenous c-Myc by Runx1 in the human T cell line Jurkat and murine primary hematopoietic cells. Endogenous Runx1 binds to multiple sites in the c-Myc locus upstream of the c-Myc transcriptional start site. Cells transduced with a C-terminally truncated Runx1 (Runx1.d190), which lacks important cofactor interaction sites and can block C-terminal-dependent functions of all Runx transcription factors, showed increased transcription of c-Myc. In order to monitor c-Myc expression in response to early and transiently-acting Runx1.d190, we generated a cell membrane-permeable TAT-Runx1.d190 fusion protein. Murine splenocytes treated with TAT-Runx1.d190 showed an increase in the transcription of c-Myc within 2 hours, peaking at 4 hours post-treatment and declining thereafter. This effect is dependent on the ability of Runx1.d190 to bind to DNA. The increase in c-Myc transcripts is correlated with increased c-Myc protein levels. Collectively, these data show that Runx1 directly regulates c-Myc transcription in a C-terminal- and DNA-binding-dependent manner. PMID:23874874

  1. Runx Transcription Factors Repress Human and Murine c-Myc Expression in a DNA-Binding and C-Terminally Dependent Manner

    PubMed Central

    Jacobs, Paejonette T.; Cao, Li; Samon, Jeremy B.; Kane, Christyne A.; Hedblom, Emmett E.; Bowcock, Anne; Telfer, Janice C.

    2013-01-01

    The transcription factors Runx1 and c-Myc have individually been shown to regulate important gene targets as well as to collaborate in oncogenesis. However, it is unknown whether there is a regulatory relationship between the two genes. In this study, we investigated the transcriptional regulation of endogenous c-Myc by Runx1 in the human T cell line Jurkat and murine primary hematopoietic cells. Endogenous Runx1 binds to multiple sites in the c-Myc locus upstream of the c-Myc transcriptional start site. Cells transduced with a C-terminally truncated Runx1 (Runx1.d190), which lacks important cofactor interaction sites and can block C-terminal-dependent functions of all Runx transcription factors, showed increased transcription of c-Myc. In order to monitor c-Myc expression in response to early and transiently-acting Runx1.d190, we generated a cell membrane-permeable TAT-Runx1.d190 fusion protein. Murine splenocytes treated with TAT-Runx1.d190 showed an increase in the transcription of c-Myc within 2 hours, peaking at 4 hours post-treatment and declining thereafter. This effect is dependent on the ability of Runx1.d190 to bind to DNA. The increase in c-Myc transcripts is correlated with increased c-Myc protein levels. Collectively, these data show that Runx1 directly regulates c-Myc transcription in a C-terminal- and DNA-binding-dependent manner. PMID:23874874

  2. A link between increased transforming activity of lymphoma-derived MYC mutant alleles, their defective regulation by p107, and altered phosphorylation of the c-Myc transactivation domain.

    PubMed Central

    Hoang, A T; Lutterbach, B; Lewis, B C; Yano, T; Chou, T Y; Barrett, J F; Raffeld, M; Hann, S R; Dang, C V

    1995-01-01

    The c-Myc protein is a transcription factor with an N-terminal transcriptional regulatory domain and C-terminal oligomerization and DNA-binding motifs. Previous studies have demonstrated that p107, a protein related to the retinoblastoma protein, binds to the c-Myc transcriptional activation domain and suppresses its activity. We sought to characterize the transforming activity and transcriptional properties of lymphoma-derived mutant MYC alleles. Alleles encoding c-Myc proteins with missense mutations in the transcriptional regulatory domain were more potent than wild-type c-Myc in transforming rodent fibroblasts. Although the mutant c-Myc proteins retained their binding to p107 in in vitro and in vivo assays, p107 failed to suppress their transcriptional activation activities. Many of the lymphoma-derived MYC alleles contain missense mutations that result in substitution for the threonine at codon 58 or affect sequences flanking this amino acid. We observed that in vivo phosphorylation of Thr-58 was absent in a lymphoma cell line with a mutant MYC allele containing a missense mutation flanking codon 58. Our in vitro studies suggest that phosphorylation of Thr-58 in wild-type c-Myc was dependent on cyclin A and required prior phosphorylation of Ser-62 by a p107-cyclin A-CDK complex. In contrast, Thr-58 remained unphosphorylated in two representative mutant c-Myc transactivation domains in vitro. Our studies suggest that missense mutations in MYC may be selected for during lymphomagenesis, because the mutant MYC proteins have altered functional interactions with p107 protein complexes and fail to be phosphorylated at Thr-58. PMID:7623799

  3. Amplification of c-MYC and MLL Genes as a Marker of Clonal Cell Progression in Patients with Myeloid Malignancy and Trisomy of Chromosomes 8 or 11.

    PubMed

    Angelova, S; Jordanova, M; Spassov, B; Shivarov, V; Simeonova, M; Christov, I; Angelova, P; Alexandrova, K; Stoimenov, A; Nikolova, V; Dimova, I; Ganeva, P; Tzvetkov, N; Hadjiev, E; Toshkov, S

    2011-12-01

    Gene amplification (amp) is one of the basic mechanisms connected with overexpression of oncogenes. The c-MYC (located in 8q24) and MLL (located in 11q23) are the most often over represented genes that lead to a rapid proliferation of the affected cell clone in patients with myeloid neoplasms. Assessment of the level of amp c-MYC or amp MLL in the cases with trisomy 8 (+8) or trisomy 11 (+11) and myeloid malignances is necessary for a more precise estimation of the disease progression. A total of 26 patients with acute myeloid leukemia (AML) and myelodysplastic syndromes (MDS) were included in the study: 18 with +8, six with +11 and two with complex karyotypes suspected of the partial trisomy. Routine cytogenetic analysis and fluorescent in situ hybridization (FISH) were applied to indicate the chromosome alterations and genes amp in the bone marrow cells. Amp c-MYC was observed in 12 from 18 (66.7%) patients with +8. All the patients with +11 demonstrated a different level of amp MLL. In most of the cases with MDS (9/10), the coincidence of the +8 or +11 with amp c-MYC or amp MLL, respectively, leads to transformation to AML and/or short overall survival. Our data suggest that amp c-MYC and amp MLL develop in conformity with +8 and +11, especially in cases with progressive deviations in the karyotype as an aggressive expansion of an aberrant cell clone and appearance of additional chromosome anomalies. PMID:24052708

  4. Oncogenic but non-essential role of N-myc downstream regulated gene 1 in the progression of esophageal squamous cell carcinoma

    PubMed Central

    Wei, Wei; Bracher-Manecke, Jacqueline C.; Zhao, Xiaohang; Davies, Neil H.; Zhou, Lanping; Ai, Runna; Oliver, Lisa; Vallette, Francois; Hendricks, Denver T.

    2013-01-01

    N-myc downstream regulated gene 1 (NDRG1/Cap43/Drg-1) has previously been shown to be dysregulated in esophageal squamous cell carcinoma (ESCC). In this study, we investigated the role of NDRG1 in the neoplastic progression of ESCC using ectopic gain-of-function and loss-of-function approaches. Stable transfectants of the KYSE30 ESCC cell line with altered NDRG1 levels were generated by lentiviral transduction. Although no measurable effects on in vitro cell proliferation were observed with altered NDRG1 expression, the ectopic overexpression of NDRG1 was positively linked to recognized markers of metastasis, angiogenesis and apoptotic evasion. Accordingly, in the nude mouse xenograft model system, NDRG1 overexpression promoted the in vivo growth of KYSE30 derived xenografts, which could be attributed to the reduced apoptotic and enhanced angiogenic activities associated with this gene. These processes were mediated in part by increased NFκB activity in NDRG1 overexpressing cells. Nevertheless, no significant phenotypic changes were observed in response to NDRG1 knock-down, suggesting that this gene might not be essential for the neoplastic progression of ESCC. Taken together, our results suggest that NDRG1 may play positive but dispensable roles in the progression of esophageal squamous cell carcinoma. PMID:23192272

  5. Resistance to everolimus driven by epigenetic regulation of MYC in ER+ breast cancers

    PubMed Central

    Bihani, Teeru; Ezell, Scott A.; Ladd, Brendon; Grosskurth, Shaun E.; Mazzola, Anne Marie; Pietras, Mark; Reimer, Corinne; Zinda, Michael; Fawell, Stephen; D'Cruz, Celina M.

    2015-01-01

    Acquired resistance to PI3K/mTOR/Akt pathway inhibitors is often associated with compensatory feedback loops involving the activation of oncogenes. Here, we have generated everolimus resistance in ER+ breast cancer cells and in long-term estrogen deprived (LTED) models that mimic progression on anti-estrogens. This allowed us to uncover MYC as a driver of mTOR inhibitor resistance. We demonstrate that both everolimus resistance and acute treatment of everolimus can lead to the upregulation of MYC mRNA, protein expression and, consequently, the enrichment of MYC signatures as revealed by RNA sequencing data. Depletion of MYC resulted in resensitization to everolimus, confirming its functional importance in this setting. Furthermore, ChIP assays demonstrate that MYC upregulation in the everolimus resistant lines is mediated by increased association of the BRD4 transcription factor with the MYC gene. Finally, JQ1, a BRD4 inhibitor combined with everolimus exhibited increased tumor growth inhibition in 3D Matrigel models and an in vivo xenograft model. These data suggest that MYC plays an important role in mediating resistance to everolimus in ER+ and ER+/LTED models. Furthermore, given the regulation ofMYCby BRD4 in this setting, these data have implications for increased therapeutic potential of combining epigenetic agents with mTOR inhibitors to effectively downregulate otherwise difficult to target transcription factors such as MYC. PMID:25537515

  6. Blocking Lactate Export by Inhibiting the Myc Target MCT1 Disables Glycolysis and Glutathione Synthesis

    PubMed Central

    Doherty, Joanne R.; Yang, Chunying; Scott, Kristen E. N.; Cameron, Michael D.; Fallahi, Mohammad; Li, Weimin; Hall, Mark A.; Amelio, Antonio L.; Mishra, Jitendra K.; Li, Fangzheng; Tortosa, Mariola; Genau, Heide Marika; Rounbehler, Robert J.; Lu, Yunqi; Dang, Chi. V.; Kumar, K. Ganesh; Butler, Andrew A.; Bannister, Thomas D.; Hooper, Andrea T.; Unsal-Kacmaz, Keziban; Roush, William R.; Cleveland, John L.

    2014-01-01

    Myc oncoproteins induce genes driving aerobic glycolysis, including lactate dehydrogenase-A that generates lactate. Here we report that Myc controls transcription of the lactate transporter SLC16A1/MCT1, and that elevated MCT1 levels are manifest in premalignant and neoplastic Eμ-Myc transgenic B cells and in human malignancies with MYC or MYCN involvement. Notably, disrupting MCT1 function leads to an accumulation of intracellular lactate that rapidly disables tumor cell growth and glycolysis, provoking marked alterations in glycolytic intermediates, and reductions in glucose transport, and in levels of ATP, NADPH and glutathione. Reductions in glutathione then lead to increases in hydrogen peroxide, mitochondrial damage and, ultimately, cell death. Finally, forcing glycolysis by metformin treatment augments this response and the efficacy of MCT1 inhibitors, suggesting an attractive combination therapy for MYC/MCT1-expressing malignancies. PMID:24285728

  7. Selective transcriptional regulation by Myc in cellular growth control and lymphomagenesis

    PubMed Central

    de Pretis, Stefano; Gorski, Marcin M.; Tesi, Alessandra; Morelli, Marco J.; Bora, Pranami; Doni, Mirko; Verrecchia, Alessandro; Tonelli, Claudia; Fagà, Giovanni; Bianchi, Valerio; Ronchi, Alberto; Low, Diana; Müller, Heiko; Guccione, Ernesto; Campaner, Stefano; Amati, Bruno

    2014-01-01

    The c-myc proto-oncogene product, Myc, is a transcription factor that binds thousands of genomic loci1. Recent work suggested that rather than up- and down-regulating selected groups of genes1-3, Myc targets all active promoters and enhancers in the genome (a phenomenon termed “invasion”) and acts as a general amplifier of transcription4,5. However, the available data did not readily discriminate between direct and indirect effects of Myc on RNA biogenesis. We addressed this issue with genome-wide chromatin immunoprecipitation and RNA expression profiles during B-cell lymphomagenesis in mice, in cultured B-cells and fibroblasts. Consistent with long-standing observations6, we detected general increases in total RNA or mRNA copies per cell (hereby termed “amplification”)4,5 when comparing actively proliferating cells with control quiescent cells: this was true whether cells were stimulated by mitogens (requiring endogenous Myc for a proliferative response)7,8 or by deregulated, oncogenic Myc activity. RNA amplification and promoter/enhancer invasion by Myc were separable phenomena that could occur without one another. Moreover, whether or not associated with RNA amplification, Myc drove the differential expression of distinct subsets of target genes. Hence, while having the potential to interact with all active/poised regulatory elements in the genome4,5,9-11, Myc does not directly act as a global transcriptional amplifier4,5. Instead, our results imply that Myc activates and represses transcription of discrete gene sets, leading to changes in cellular state that can in turn feed back on global RNA production and turnover. PMID:25043028

  8. c-MYC-Induced Genomic Instability

    PubMed Central

    Kuzyk, Alexandra; Mai, Sabine

    2014-01-01

    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. PMID:24692190

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

    PubMed

    Fan, L; Peng, G; Sahgal, N; Fazli, L; Gleave, M; Zhang, Y; Hussain, A; Qi, J

    2016-05-12

    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 deregulated 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

  10. N-myc downstream-regulated gene 1 is mutated in hereditary motor and sensory neuropathy-Lom.

    PubMed

    Kalaydjieva, L; Gresham, D; Gooding, R; Heather, L; Baas, F; de Jonge, R; Blechschmidt, K; Angelicheva, D; Chandler, D; Worsley, P; Rosenthal, A; King, R H; Thomas, P K

    2000-07-01

    Hereditary motor and sensory neuropathies, to which Charcot-Marie-Tooth (CMT) disease belongs, are a common cause of disability in adulthood. Growing awareness that axonal loss, rather than demyelination per se, is responsible for the neurological deficit in demyelinating CMT disease has focused research on the mechanisms of early development, cell differentiation, and cell-cell interactions in the peripheral nervous system. Autosomal recessive peripheral neuropathies are relatively rare but are clinically more severe than autosomal dominant forms of CMT, and understanding their molecular basis may provide a new perspective on these mechanisms. Here we report the identification of the gene responsible for hereditary motor and sensory neuropathy-Lom (HMSNL). HMSNL shows features of Schwann-cell dysfunction and a concomitant early axonal involvement, suggesting that impaired axon-glia interactions play a major role in its pathogenesis. The gene was previously mapped to 8q24.3, where conserved disease haplotypes suggested genetic homogeneity and a single founder mutation. We have reduced the HMSNL interval to 200 kb and have characterized it by means of large-scale genomic sequencing. Sequence analysis of two genes located in the critical region identified the founder HMSNL mutation: a premature-termination codon at position 148 of the N-myc downstream-regulated gene 1 (NDRG1). NDRG1 is ubiquitously expressed and has been proposed to play a role in growth arrest and cell differentiation, possibly as a signaling protein shuttling between the cytoplasm and the nucleus. We have studied expression in peripheral nerve and have detected particularly high levels in the Schwann cell. Taken together, these findings point to NDRG1 having a role in the peripheral nervous system, possibly in the Schwann-cell signaling necessary for axonal survival. PMID:10831399

  11. NCYM promotes calpain-mediated Myc-nick production in human MYCN-amplified neuroblastoma cells

    SciTech Connect

    Shoji, Wataru; Suenaga, Yusuke; Kaneko, Yoshiki; Islam, S.M. Rafiqul; Alagu, Jennifer; Yokoi, Sana; Nio, Masaki; Nakagawara, Akira

    2015-06-05

    NCYM is a cis-antisense gene of MYCN and is amplified in human neuroblastomas. High NCYM expression is associated with poor prognoses, and the NCYM protein stabilizes MYCN to promote proliferation of neuroblastoma cells. However, the molecular mechanisms of NCYM in the regulation of cell survival have remained poorly characterized. Here we show that NCYM promotes cleavage of MYCN to produce the anti-apoptotic protein, Myc-nick, both in vitro and in vivo. NCYM and Myc-nick were induced at G2/M phase, and NCYM knockdown induced apoptotic cell death accompanied by Myc-nick downregulation. These results reveal a novel function of NCYM as a regulator of Myc-nick production in human neuroblastomas. - Highlights: • NCYM promotes cleavages of MYC and MYCN to produce Myc-nick in vitro. • NCYM increases Myc-nick production in MYCN-amplified neuroblastoma cells. • NCYM knockdown decreases Myc-nick production and induces apoptosis at G2/M phase.

  12. The MYC Road to Hearing Restoration

    PubMed Central

    Kopecky, Benjamin; Fritzsch, Bernd

    2012-01-01

    Current treatments for hearing loss, the most common neurosensory disorder, do not restore perfect hearing. Regeneration of lost organ of Corti hair cells through forced cell cycle re-entry of supporting cells or through manipulation of stem cells, both avenues towards a permanent cure, require a more complete understanding of normal inner ear development, specifically the balance of proliferation and differentiation required to form and to maintain hair cells. Direct successful alterations to the cell cycle result in cell death whereas regulation of upstream genes is insufficient to permanently alter cell cycle dynamics. The Myc gene family is uniquely situated to synergize upstream pathways into downstream cell cycle control. There are three Mycs that are embedded within the Myc/Max/Mad network to regulate proliferation. The function of the two ear expressed Mycs, N-Myc and L-Myc were unknown less than two years ago and their therapeutic potentials remain speculative. In this review, we discuss the roles the Mycs play in the body and what led us to choose them to be our candidate gene for inner ear therapies. We will summarize the recently published work describing the early and late effects of N-Myc and L-Myc on hair cell formation and maintenance. Lastly, we detail the translational significance of our findings and what future work must be performed to make the ultimate hearing aid: the regeneration of the organ of Corti. PMID:24710525

  13. Cooperation between the polyomavirus middle-T-antigen gene and the human c-myc oncogene in a rat thyroid epithelial differentiated cell line: model of in vitro progression.

    PubMed Central

    Berlingieri, M T; Portella, G; Grieco, M; Santoro, M; Fusco, A

    1988-01-01

    Two rat thyroid epithelial differentiated cell lines, PC Cl 3 and PC myc, were infected with the polyoma murine leukemia virus (PyMLV) carrying the Middle-T-antigen gene of polyomavirus. After infection, both cell lines acquired the typical markers of neoplastic transformation; however, the PC myc cells showed a greater malignant phenotype. Furthermore, the thyroid differentiated functions were completely suppressed in PC myc cells transformed by PyMLV, whereas they were, at least partially, retained in PC Cl 3 cells transformed by PyMLV, and in particular, thyroglobulin synthesis and secretion were not affected at all. Since no differences in the expression of the middle-T-antigen gene were observed in the two PyMLV-transformed cell lines, the different properties shown by these two infected cell lines must be ascribed to the expression of the c-myc oncogene. Images PMID:2838744

  14. Cooperation between the polyomavirus Middle-T-antigen gene and the human c-myc oncogene in a rat thyroid epithelial differentiated cell line: Model of in vitro progression

    SciTech Connect

    Berlingieri, M.T.; Portella, G.; Grieco, M.; Santoro, M.; Fusco, A.

    1988-05-01

    Two rat thyroid epithelial differentiated cell lines, PC CI 3 and PC myc, were infected with the polyoma murine leukemia virus (PyMLV) carrying the Middle-T-antigen gene of polyomavirus. After infection, both cell lines acquired the typical markers of neoplastic transformation; however, the PC myc cells showed a greater malignant phenotype. Furthermore, the thyroid differentiated functions were completely suppressed in PC myc cells transformed by PyMLV, whereas they were, at least partially, retained in PC CI 3 cells transformed by PyMLV, and in particular, thyroglobulin synthesis and secretion were not affected at all. Since no differences in the expression of the middle-T-antigen gene were observed in the two PyMLV-transformed cell lines, the different properties shown by these two infected cell lines must be ascribed to the expression of the c-myc oncogene.

  15. miR-17–92 explains MYC oncogene addiction

    PubMed Central

    Li, Yulin; Casey, Stephanie C; Choi, Peter S; Felsher, Dean W

    2014-01-01

    MYC regulates tumorigenesis by coordinating the expression of thousands of genes. We found that MYC appears to regulate the decisions between cell survival versus death and self-renewal versus senescence through the microRNA miR-17–92 cluster. Addiction to the MYC oncogene may therefore in fact be an addiction to miR-17–92. PMID:27308380

  16. Sequential and Coordinated Actions of c-Myc and N-Myc Control Appendicular Skeletal Development

    PubMed Central

    Ota, Sara; Akiyama, Haruhiko; Keene, Douglas R.; Hurlin, Peter J.

    2011-01-01

    Background During limb development, chondrocytes and osteoblasts emerge from condensations of limb bud mesenchyme. These cells then proliferate and differentiate in separate but adjacent compartments and function cooperatively to promote bone growth through the process of endochondral ossification. While many aspects of limb skeletal formation are understood, little is known about the mechanisms that link the development of undifferentiated limb bud mesenchyme with formation of the precartilaginous condensation and subsequent proliferative expansion of chondrocyte and osteoblast lineages. The aim of this study was to gain insight into these processes by examining the roles of c-Myc and N-Myc in morphogenesis of the limb skeleton. Methodology/Principal Findings To investigate c-Myc function in skeletal development, we characterized mice in which floxed c-Myc alleles were deleted in undifferentiated limb bud mesenchyme with Prx1-Cre, in chondro-osteoprogenitors with Sox9-Cre and in osteoblasts with Osx1-Cre. We show that c-Myc promotes the proliferative expansion of both chondrocytes and osteoblasts and as a consequence controls the process of endochondral growth and ossification and determines bone size. The control of proliferation by c-Myc was related to its effects on global gene transcription, as phosphorylation of the C-Terminal Domain (pCTD) of RNA Polymerase II, a marker of general transcription initiation, was tightly coupled to cell proliferation of growth plate chondrocytes where c-Myc is expressed and severely downregulated in the absence of c-Myc. Finally, we show that combined deletion of N-Myc and c-Myc in early limb bud mesenchyme gives rise to a severely hypoplastic limb skeleton that exhibits features characteristic of individual c-Myc and N-Myc mutants. Conclusions/Significance Our results show that N-Myc and c-Myc act sequentially during limb development to coordinate the expansion of key progenitor populations responsible for forming the limb

  17. The Interaction of Myc with Miz1 Defines Medulloblastoma Subgroup Identity.

    PubMed

    Vo, BaoHan T; Wolf, Elmar; Kawauchi, Daisuke; Gebhardt, Anneli; Rehg, Jerold E; Finkelstein, David; Walz, Susanne; Murphy, Brian L; Youn, Yong Ha; Han, Young-Goo; Eilers, Martin; Roussel, Martine F

    2016-01-11

    Four distinct subgroups of cerebellar medulloblastomas (MBs) differ in their histopathology, molecular profiles, and prognosis. c-Myc (Myc) or MycN overexpression in granule neuron progenitors (GNPs) induces Group 3 (G3) or Sonic Hedgehog (SHH) MBs, respectively. Differences in Myc and MycN transcriptional profiles depend, in part, on their interaction with Miz1, which binds strongly to Myc but not MycN, to target sites on chromatin. Myc suppresses ciliogenesis and reprograms the transcriptome of SHH-dependent GNPs through Miz1-dependent gene repression to maintain stemness. Genetic disruption of the Myc/Miz1 interaction inhibited G3 MB development. Target genes of Myc/Miz1 are repressed in human G3 MBs but not in other subgroups. Therefore, the Myc/Miz1 interaction is a defining hallmark of G3 MB development. PMID:26766587

  18. Factor-binding element in the human c-myc promoter involved in transcriptional regulation by transforming growth factor. beta. 1 and by the retinoblastoma gene product

    SciTech Connect

    Pietenpol, J.A.; Stein, R.W.; Moses, H.L. ); Muenger, K.; Howley, P.M. )

    1991-11-15

    Previous studies have shown that transforming growth factor {beta}1 (TGF-{beta}1) inhibition of keratinocyte proliferation involves suppression of c-myc transcription, and indirect evidence has suggested that the retinoblastoma gene product (pRB) may be involved in this process. In this study, transient expression of pRB in skin keratinocytes was shown to repress transcription of the human c-myc promoter region was required for regulation by both TGF-{beta}1 and pRB. These sequences, termed the TGF-{beta} control element (TCE), lie between positions {minus}86 and {minus}63 relative to the P1 transcription start site. Oligonucleotides containing the TCE bound to several nuclear factors in mobility-shift assays using extracts from cells with or without normal pRB. Binding of some factors was inhibited by TGF-{beta}1 treatment of TGF-{beta}-sensitive but not TGF-{beta}-insensitive cells. These data indicate that pRB can suppress c-myc transcription and growth inhibition.

  19. Correlation of N-myc downstream-regulated gene 1 subcellular localization and lymph node metastases of colorectal neoplasms

    SciTech Connect

    Song, Yan; Lv, Liyang; Du, Juan; Yue, Longtao; Cao, Lili

    2013-09-20

    Highlights: •We clarified NDRG1 subcellular location in colorectal cancer. •We found the changes of NDRG1 distribution during colorectal cancer progression. •We clarified the correlation between NDRG1 distribution and lymph node metastasis. •It is possible that NDRG1 subcellular localization may determine its function. •Maybe NDRG1 is valuable early diagnostic markers for metastasis. -- Abstract: In colorectal neoplasms, N-myc downstream-regulated gene 1 (NDRG1) is a primarily cytoplasmic protein, but it is also expressed on the cell membrane and in the nucleus. NDRG1 is involved in various stages of tumor development in colorectal cancer, and it is possible that the different subcellular localizations may determine the function of NDRG1 protein. Here, we attempt to clarify the characteristics of NDRG1 protein subcellular localization during the progression of colorectal cancer. We examined NDRG1 expression in 49 colorectal cancer patients in cancerous, non-cancerous, and corresponding lymph node tissues. Cytoplasmic and membrane NDRG1 expression was higher in the lymph nodes with metastases than in those without metastases (P < 0.01). Nuclear NDRG1 expression in colorectal neoplasms was significantly higher than in the normal colorectal mucosa, and yet the normal colorectal mucosa showed no nuclear expression. Furthermore, our results showed higher cytoplasmic NDRG1 expression was better for differentiation, and higher membrane NDRG1 expression resulted in a greater possibility of lymph node metastasis. These data indicate that a certain relationship between the cytoplasmic and membrane expression of NDRG1 in lymph nodes exists with lymph node metastasis. NDRG1 expression may translocate from the membrane of the colorectal cancer cells to the nucleus, where it is involved in lymph node metastasis. Combination analysis of NDRG1 subcellular expression and clinical variables will help predict the incidence of lymph node metastasis.

  20. The Interplay between Myc and CTP Synthase in Drosophila

    PubMed Central

    Aughey, Gabriel N.; Grice, Stuart J.; Liu, Ji-Long

    2016-01-01

    CTP synthase (CTPsyn) is essential for the biosynthesis of pyrimidine nucleotides. It has been shown that CTPsyn is incorporated into a novel cytoplasmic structure which has been termed the cytoophidium. Here, we report that Myc regulates cytoophidium formation during Drosophila oogenesis. We have found that Myc protein levels correlate with cytoophidium abundance in follicle epithelia. Reducing Myc levels results in cytoophidium loss and small nuclear size in follicle cells, while overexpression of Myc increases the length of cytoophidia and the nuclear size of follicle cells. Ectopic expression of Myc induces cytoophidium formation in late stage follicle cells. Furthermore, knock-down of CTPsyn is sufficient to suppress the overgrowth phenotype induced by Myc overexpression, suggesting CTPsyn acts downstream of Myc and is required for Myc-mediated cell size control. Taken together, our data suggest a functional link between Myc, a renowned oncogene, and the essential nucleotide biosynthetic enzyme CTPsyn. PMID:26889675

  1. The MYC 3′ Wnt-Responsive Element Drives Oncogenic MYC Expression in Human Colorectal Cancer Cells

    PubMed Central

    Rennoll, Sherri A.; Eshelman, Melanie A.; Raup-Konsavage, Wesley M.; Kawasawa, Yuka Imamura; Yochum, Gregory S.

    2016-01-01

    Mutations in components of the Wnt/β-catenin signaling pathway drive colorectal cancer (CRC) by deregulating expression of downstream target genes including the c-MYC proto-oncogene (MYC). The critical regulatory DNA enhancer elements that control oncogenic MYC expression in CRC have yet to be fully elucidated. In previous reports, we correlated T-cell factor (TCF) and β-catenin binding to the MYC 3′ Wnt responsive DNA element (MYC 3′ WRE) with MYC expression in HCT116 cells. Here we used CRISPR/Cas9 to determine whether this element is a critical driver of MYC. We isolated a clonal population of cells that contained a deletion of a single TCF binding element (TBE) within the MYC 3′ WRE. This deletion reduced TCF/β-catenin binding to this regulatory element and decreased MYC expression. Using RNA-Seq analysis, we found altered expression of genes that regulate metabolic processes, many of which are known MYC target genes. We found that 3′ WRE-Mut cells displayed a reduced proliferative capacity, diminished clonogenic growth, and a decreased potential to form tumors in vivo. These findings indicate that the MYC 3′ WRE is a critical driver of oncogenic MYC expression and suggest that this element may serve as a therapeutic target for CRC. PMID:27223305

  2. N-Myc downstream-regulated gene 2 suppresses the proliferation of T24 human bladder cancer cells via induction of oncosis

    PubMed Central

    HUANG, JIE; WU, ZHOU; WANG, GUANGXIU; CAI, YINGXIAN; CAI, MINSHAN; LI, YAOZHANG

    2015-01-01

    Previous studies have reported the antitumor activity of N-Myc downstream-regulated gene 2 (NDRG2), a novel p53-inducible gene, in several types of cancer. The present study aimed to investigate the effects of NDRG2 expression on the proliferation of a human bladder cancer cell line. NDRG2 and control green fluorescent protein (GFP) recombinant adenovirus plasmids were constructed and transfected into a bladder cancer cell line with mutant p53 (T24 cells). NDRG2 expression was analyzed using western blot analysis and immunofluorescence assay (IFA); in addition, the subcellular localization of NDRG2 was detected using a confocal microscope. The proliferation rate of cells was measured using colony formation and MTT assays. Furthermore, the cell cycle of transfected T24 cells was detected by flow cytometry. The results indicated that T24 cells expressed low levels of NDRG2 prior to infection with GFP-NDRG2 recombinant adenovirus; by contrast, following infection, NDRG2 was primarily over-expressed in mitochondria. The proliferation rate of T24 cells was significantly reduced by NDRG2 expression (P<0.01). In addition, 82.1% of NDRG2-expressing cells were in S-phase, compared to 74.4% in the control virus-infected cells (P<0.05). Furthermore, upregulation of NDRG2 induced an increase in oncosis, rather than apoptosis, in T24 cell. In conclusion, the results of the present study indicated that NDRG2 expression in mitochondria may arrest bladder cancer cells in S-phase as well as decrease cell proliferation through inducing oncosis. It was therefore proposed that NDRG2 was not only a biomarker, but also a tumor suppressor for bladder cancer. PMID:26239274

  3. Design of a novel triple helix-forming oligodeoxyribonucleotide directed to the major promoter of the c-myc gene

    PubMed Central

    McGuffie, E. M.; Catapano, C. V.

    2002-01-01

    Altered expression of c-myc is implicated in pathogenesis and progression of many human cancers. Triple helix-forming oligonucleotides (TFOs) directed to a polypurine/polypyrimidine sequence in a critical regulatory region near the c-myc P2 promoter have been shown to inhibit c-myc transcription in vitro and in cells. However, these guanine-rich TFOs had moderate binding affinity and required high concentrations for activity. The 23 bp myc P2 sequence is split equally into AT- and GC-rich tracts. Gel mobility analysis of a series of short TFOs directed in parallel and anti-parallel orientation to the purine strand of each tract showed that only parallel CT and anti-parallel GT TFOs formed stable triplex on the AT- and GC-rich tracts, respectively. A novel full-length GTC TFO was designed to bind simultaneously in parallel and anti-parallel orientation to the polypurine strand. Gel-shift and footprinting assays showed that the new TFO formed a triple helix in physiological conditions with significantly higher affinity than an anti-parallel TFO. Protein-binding assays showed that 1 µM GTC TFO inhibited binding of nuclear transcription factors to the P2 promoter sequence. The novel TFO can be developed into a potent antigene agent, and its design strategy applied to similar genomic sequences, thus expanding the TFO repertoire. PMID:12060688

  4. Disruption of Myc-Tubulin Interaction by Hyperphosphorylation of c-Myc during Mitosis or by Constitutive Hyperphosphorylation of Mutant c-Myc in Burkitt's Lymphoma

    PubMed Central

    Niklinski, Jacek; Claassen, Gisela; Meyers, Cheryl; Gregory, Mark A.; Allegra, Carmen J.; Kaye, Frederic J.; Hann, Stephen R.; Zajac-Kaye, Maria

    2000-01-01

    Somatic mutations at Thr-58 of c-Myc have been detected in Burkitt's lymphoma (BL) tumors and have been shown to affect the transforming potential of the Myc oncoprotein. In addition, the N-terminal domain of c-Myc has been shown to interact with microtubules in vivo, and the binding of c-Myc to α-tubulin was localized to amino acids 48 to 135 within the c-Myc protein. We demonstrate that c-Myc proteins harboring a naturally occurring mutation at Thr-58 from BL cell lines have increased stability and are constitutively hyperphosphorylated, which disrupts the in vivo interaction of c-Myc with α-tubulin. In addition, we show that wild-type c-Myc–α-tubulin interactions are also disrupted during a transient mitosis-specific hyperphosphorylation of c-Myc, which resembles the constitutive hyperphosphorylation pattern of Thr-58 in BL cells. PMID:10866684

  5. A deficiency in Mdm2 binding protein (MTBP) inhibits Myc-induced B cell proliferation and lymphomagenesis

    PubMed Central

    Odvody, Jessica; Vincent, Tiffaney; Arrate, Maria Pia; Grieb, Brian; Wang, Shuo; Garriga, Judit; Lozano, Guillermina; Iwakuma, Tomoo; Haines, Dale S.; Eischen, Christine M.

    2010-01-01

    Mdm2 binding protein (MTBP) has been implicated in cell cycle arrest and the Mdm2-p53 tumor suppressor pathway through its interaction with Mdm2. To determine the function of MTBP in tumorigenesis and its potential role in the Mdm2-p53 pathway, we crossed Mtbp deficient mice to Eµ-myc transgenic mice, in which overexpression of the oncogene c-Myc induces B cell lymphomas primarily through inactivation of the Mdm2-p53 pathway. We report that Myc-induced B cell lymphoma development in Mtbp heterozygous mice was profoundly delayed. Surprisingly, reduced levels of Mtbp did not lead to an increase in B cell apoptosis or affect Mdm2. Instead, an Mtbp deficiency inhibited Myc-induced proliferation and the upregulation of Myc target genes necessary for cell growth. Consistent with a role in proliferation, Mtbp expression was induced by Myc and other factors that promote cell cycle progression and was elevated in lymphomas from humans and mice. Therefore, Mtbp functioned independent of Mdm2 and was a limiting factor for the proliferative and transforming functions of Myc. Thus, Mtbp is a previously unrecognized regulator of Myc-induced tumorigenesis. PMID:20305689

  6. Ecdysteroid promotes cell cycle progression in the Bombyx wing disc through activation of c-Myc.

    PubMed

    Moriyama, Minoru; Osanai, Kohji; Ohyoshi, Tomokazu; Wang, Hua-Bing; Iwanaga, Masashi; Kawasaki, Hideki

    2016-03-01

    Developmental switching from growth to metamorphosis in imaginal primordia is an essential process of adult body planning in holometabolous insects. Although it is disciplined by a sequential action of the ecdysteroid, molecular mechanisms linking to cell proliferation are poorly understood. In the present study, we investigated the expression control of cell cycle-related genes by the ecdysteroid using the wing disc of the final-instar larvae of the silkworm, Bombyx mori. We found that the expression level of c-myc was remarkably elevated in the post-feeding cell proliferation phase, which coincided with a small increase in ecdysteroid titer. An in vitro wing disc culture showed that supplementation of the moderate level of the ecdysteroid upregulated c-myc expression within an hour and subsequently increased the expression of cell cycle core regulators, including A-, B-, D-, and E-type cyclin genes, Cdc25 and E2F1. We demonstrated that c-myc upregulation by the ecdysteroid was not inhibited in the presence of a protein synthesis inhibitor, suggesting a possibility that the ecdysteroid directly stimulates c-myc expression. Finally, results from the administration of a c-Myc inhibitor demonstrated that c-Myc plays an essential role in 20E-inducible cell proliferation. These findings suggested a novel pathway for ecdysteroid-inducible cell proliferation in insects, and it is likely to be conserved between insects and mammals in terms of steroid hormone regulation. PMID:26696544

  7. Neoplastic transformation and tumorigenesis by the human protooncogene MYC.

    PubMed Central

    Ramsay, G M; Moscovici, G; Moscovici, C; Bishop, J M

    1990-01-01

    Damage to the protooncogene MYC has been implicated in the genesis of diverse human tumors, but the tumorigenic potential of the isolated gene has been disputed. Here we report the use of a retroviral vector to test the potency of human MYC for neoplastic transformation in avian cells. We found that sustained and abundant expression of MYC can transform both embryonic fibroblasts and hematopoietic cells and elicit granulocytic leukemias in chickens. Transformation by MYC is accompanied by changes in diverse aspects of cellular phenotype, including morphology, ability to grow in suspension, rate of proliferation, the structure of the cytoskeleton, and the composition of the extracellular matrix. Nevertheless, the biological potency of MYC is inherently constrained when compared to that of the retroviral oncogene v-myc. Our findings enlarge on previous descriptions of neoplastic transformation by MYC and sustain the view that ungoverned expression of the gene can contribute to the genesis of human tumors. Images PMID:2156260

  8. c-Myc over-expression in Ramos Burkitt's lymphoma cell line predisposes to iron homeostasis disruption in vitro

    SciTech Connect

    Habel, Marie-Eve; Jung, Daniel . E-mail: djung@hema-quebec.qc.ca

    2006-03-24

    Burkitt's lymphoma is an aggressive B-cell neoplasm resulting from deregulated c-myc expression. We have previously shown that proliferation of Burkitt's lymphoma cell lines such as Ramos is markedly reduced by iron treatment. It has been shown that iron induces expression of c-myc which, owing to its transcriptional regulatory functions, regulates genes involved in iron metabolism. Transient enhancement of c-myc expression by iron could increase the expression of genes involved in iron incorporation, which could lead to an accumulation of intracellular free iron. Here, we have investigated whether cells with a high basal level of c-Myc were more likely to accumulate free iron. Our results suggest that the basal level of c-Myc in Ramos cells is twofold higher than what is seen in HL-60 cells. Moreover, in Ramos cells, where c-Myc is expressed at a high level, H-ferritin expression is down-regulated, transferrin receptor (CD71) expression is increased, and ferritin translation is inhibited. These modifications in iron metabolism, resulting from the strong basal expression of c-Myc, and amplified by iron addition, could lead to a disruption in homeostasis and consequently to growth arrest.

  9. Continuous Hypoxic Culturing of Human Embryonic Stem Cells Enhances SSEA-3 and MYC Levels

    PubMed Central

    Laiho, Asta; Rahkonen, Nelly; Emani, Maheswara Reddy; Viitala, Miro; Laurila, Kirsti; Sahla, Roosa; Lund, Riikka; Lähdesmäki, Harri; Jaakkola, Panu; Lahesmaa, Riitta

    2013-01-01

    Low oxygen tension (hypoxia) contributes critically to pluripotency of human embryonic stem cells (hESCs) by preventing spontaneous differentiation and supporting self-renewal. However, it is not well understood how hESCs respond to reduced oxygen availability and what are the molecular mechanisms maintaining pluripotency in these conditions. In this study we characterized the transcriptional and molecular responses of three hESC lines (H9, HS401 and HS360) on short (2 hours), intermediate (24 hours) and prolonged (7 days) exposure to low oxygen conditions (4% O2). In response to prolonged hypoxia the expression of pluripotency surface marker SSEA-3 was increased. Furthermore, the genome wide gene-expression analysis revealed that a substantial proportion (12%) of all hypoxia-regulated genes in hESCs, were directly linked to the mechanisms controlling pluripotency or differentiation. Moreover, transcription of MYC oncogene was induced in response to continuous hypoxia. At the protein level MYC was stabilized through phosphorylation already in response to a short hypoxic exposure. Total MYC protein levels remained elevated throughout all the time points studied. Further, MYC protein expression in hypoxia was affected by silencing HIF2α, but not HIF1α. Since MYC has a crucial role in regulating pluripotency we propose that induction of sustained MYC expression in hypoxia contributes to activation of transcriptional programs critical for hESC self-renewal and maintenance of enhanced pluripotent state. PMID:24236059

  10. Inhibitory effect of cytotoxic stilbenes related to resveratrol on the expression of the VEGF, hTERT and c-Myc genes.

    PubMed

    Martí-Centelles, Rosa; Falomir, Eva; Murga, Juan; Carda, Miguel; Marco, J Alberto

    2015-10-20

    A group of thirty-nine stilbene derivatives, prepared by means of Heck coupling reactions, has been investigated for their cytotoxicity, as well as for their ability to inhibit the production of the vascular endothelial growth factor (VEGF) and the activation of telomerase. The ability of these compounds to inhibit proliferation of two tumoral cell lines (HT-29 and MCF-7) and one non tumoral cell line (HEK-293) was first determined. Subsequently, we determined the capacity of the compounds to inhibit the secretion of VEGF in the aforementioned cell lines and to downregulate the expression of the VEGF, hTERT and c-Myc genes, the two latter involved in the control of the activation of telomerase. One of the synthetic stilbenes, (E)-4-(4-methoxystyryl)aniline, showed strong cytotoxicity and proved able to cause a marked decrease both in the secretion of VEGF and in the expression of the hTERT and c-Myc genes, in all cases at concentrations in the low nanomolar range. PMID:26402726

  11. Enhanced angiogenesis, hypoxia and neutrophil recruitment during Myc-induced liver tumorigenesis in zebrafish.

    PubMed

    Zhao, Ye; Huang, Xiaoqian; Ding, Tony Weixi; Gong, Zhiyuan

    2016-01-01

    Angiogenesis, hypoxia and immune cells are important components in tumor microenvironment affecting tumor growth. Here we employed a zebrafish liver tumor model to investigate the effect of Myc expression on angiogenesis, hypoxia and tumor-infiltrated neutrophils during the tumor initiation stage. We found that induced Myc expression in the liver caused a dramatic increase of liver size with neoplastic features. The tumorigenic liver was accompanied by enhanced angiogenesis and inhibition of angiogenesis by an inhibitor (SU5416 or sunitinib) hindered the tumorigenic growth, suggesting an essential role of angiogenesis in tumorigenic growth of liver tumor in this zebrafish model. Myc induction also caused hypoxia, which could be further enhanced by hypoxia activator, ML228, to lead to a further enlargement of tumorigenic liver. Furthermore, Myc overexpression incurred an increase of liver-infiltrated neutrophils and the increase could be suppressed by angiogenesis inhibitors or by morpholino knockdown inhibition of neutrophil differentiation, leading to a suppression of growth of tumorigenic livers. Finally, the enhanced angiogenesis, hypoxia and tumor-infiltrated neutrophils by Myc overexpression were validated by RT-qPCR examination of expression of relevant biomarker genes. In sum, the current study demonstrated that the Myc-induced liver tumor model in zebrafish provides an excellent platform for study of tumor microenvironment. PMID:27549025

  12. Enhanced angiogenesis, hypoxia and neutrophil recruitment during Myc-induced liver tumorigenesis in zebrafish

    PubMed Central

    Zhao, Ye; Huang, Xiaoqian; Ding, Tony Weixi; Gong, Zhiyuan

    2016-01-01

    Angiogenesis, hypoxia and immune cells are important components in tumor microenvironment affecting tumor growth. Here we employed a zebrafish liver tumor model to investigate the effect of Myc expression on angiogenesis, hypoxia and tumor-infiltrated neutrophils during the tumor initiation stage. We found that induced Myc expression in the liver caused a dramatic increase of liver size with neoplastic features. The tumorigenic liver was accompanied by enhanced angiogenesis and inhibition of angiogenesis by an inhibitor (SU5416 or sunitinib) hindered the tumorigenic growth, suggesting an essential role of angiogenesis in tumorigenic growth of liver tumor in this zebrafish model. Myc induction also caused hypoxia, which could be further enhanced by hypoxia activator, ML228, to lead to a further enlargement of tumorigenic liver. Furthermore, Myc overexpression incurred an increase of liver-infiltrated neutrophils and the increase could be suppressed by angiogenesis inhibitors or by morpholino knockdown inhibition of neutrophil differentiation, leading to a suppression of growth of tumorigenic livers. Finally, the enhanced angiogenesis, hypoxia and tumor-infiltrated neutrophils by Myc overexpression were validated by RT-qPCR examination of expression of relevant biomarker genes. In sum, the current study demonstrated that the Myc-induced liver tumor model in zebrafish provides an excellent platform for study of tumor microenvironment. PMID:27549025

  13. MINCR is a MYC-induced lncRNA able to modulate MYC's transcriptional network in Burkitt lymphoma cells.

    PubMed

    Doose, Gero; Haake, Andrea; Bernhart, Stephan H; López, Cristina; Duggimpudi, Sujitha; Wojciech, Franziska; Bergmann, Anke K; Borkhardt, Arndt; Burkhardt, Birgit; Claviez, Alexander; Dimitrova, Lora; Haas, Siegfried; Hoell, Jessica I; Hummel, Michael; Karsch, Dennis; Klapper, Wolfram; Kleo, Karsten; Kretzmer, Helene; Kreuz, Markus; Küppers, Ralf; Lawerenz, Chris; Lenze, Dido; Loeffler, Markus; Mantovani-Löffler, Luisa; Möller, Peter; Ott, German; Richter, Julia; Rohde, Marius; Rosenstiel, Philip; Rosenwald, Andreas; Schilhabel, Markus; Schneider, Markus; Scholz, Ingrid; Stilgenbauer, Stephan; Stunnenberg, Hendrik G; Szczepanowski, Monika; Trümper, Lorenz; Weniger, Marc A; Hoffmann, Steve; Siebert, Reiner; Iaccarino, Ingram

    2015-09-22

    Despite the established role of the transcription factor MYC in cancer, little is known about the impact of a new class of transcriptional regulators, the long noncoding RNAs (lncRNAs), on MYC ability to influence the cellular transcriptome. Here, we have intersected RNA-sequencing data from two MYC-inducible cell lines and a cohort of 91 B-cell lymphomas with or without genetic variants resulting in MYC overexpression. We identified 13 lncRNAs differentially expressed in IG-MYC-positive Burkitt lymphoma and regulated in the same direction by MYC in the model cell lines. Among them, we focused on a lncRNA that we named MYC-induced long noncoding RNA (MINCR), showing a strong correlation with MYC expression in MYC-positive lymphomas. To understand its cellular role, we performed RNAi and found that MINCR knockdown is associated with an impairment in cell cycle progression. Differential gene expression analysis after RNAi showed a significant enrichment of cell cycle genes among the genes down-regulated after MINCR knockdown. Interestingly, these genes are enriched in MYC binding sites in their promoters, suggesting that MINCR acts as a modulator of the MYC transcriptional program. Accordingly, MINCR knockdown was associated with a reduction in MYC binding to the promoters of selected cell cycle genes. Finally, we show that down-regulation of Aurora kinases A and B and chromatin licensing and DNA replication factor 1 may explain the reduction in cellular proliferation observed on MINCR knockdown. We, therefore, suggest that MINCR is a newly identified player in the MYC transcriptional network able to control the expression of cell cycle genes. PMID:26351698

  14. 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

    SciTech Connect

    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.

    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.

  15. Deregulated Myc Requires MondoA/Mlx for Metabolic Reprogramming and Tumorigenesis

    PubMed Central

    Carroll, Patrick A.; Diolaiti, Daniel; McFerrin, Lisa; Gu, Haiwei; Djukovic, Danijel; Du, Jianhai; Cheng, Pei Feng; Anderson, Sarah; Ulrich, Michelle; Hurley, James B.; Raftery, Daniel; Ayer, Donald E.; Eisenman, Robert N.

    2014-01-01

    SUMMARY Deregulated Myc transcriptionally reprograms cell metabolism to promote neoplasia. Here we show that oncogenic Myc requires the Myc superfamily member MondoA, a nutrient-sensing transcription factor, for tumorigenesis. Knockdown of MondoA, or its dimerization partner Mlx, blocks Myc-induced reprogramming of multiple metabolic pathways resulting in apoptosis. Identification, and knockdown, of genes co-regulated by Myc and MondoA has allowed us to define metabolic functions required by deregulated Myc and demonstrate a critical role for lipid biosynthesis in survival of Myc-driven cancer. Furthermore, overexpression of a subset of Myc and MondoA co-regulated genes correlates with poor outcome of patients with diverse cancers. Co-regulation of cancer metabolism by Myc and MondoA provides the potential for therapeutics aimed at inhibiting MondoA and its target genes. PMID:25640402

  16. Puma and to a lesser extent Noxa are suppressors of Myc-induced lymphomagenesis.

    PubMed

    Michalak, E M; Jansen, E S; Happo, L; Cragg, M S; Tai, L; Smyth, G K; Strasser, A; Adams, J M; Scott, C L

    2009-05-01

    Evasion of apoptosis contributes importantly to c-Myc-induced tumorigenesis. The BH3-only Bcl-2 family members Puma and Noxa are critical pro-apoptotic transcriptional targets of p53, a major mediator of Myc-induced apoptosis and suppressor of Myc-induced tumorigenesis. Hence, we have explored the impact of their individual or combined loss on myc-driven lymphomagenesis. Notably, Puma deficiency both increased B-lineage cells and accelerated the development of B lymphoma, accompanied by leukaemia, but not of pre-B lymphoma. Noxa deficiency alone also increased B-lineage cells but did not accelerate lymphomagenesis. However, its deficiency combined with loss of one puma allele produced more rapid onset of both pre-B and B lymphomas than did loss of a single puma allele alone. Nevertheless, the acceleration evoked by loss of both genes was not as marked as that caused by p53 heterozygosity. These results show that Puma imposes a significant, and Noxa a minor barrier to c-Myc-driven lymphomagenesis. They also indicate that additional BH3-only proteins probably also drive Myc-induced apoptosis and that non-apoptotic functions of p53 may contribute substantially to its tumour suppressor role. PMID:19148184

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

    PubMed Central

    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

  18. Targeting MYC Expression through G-Quadruplexes

    PubMed Central

    Brooks, Tracy A.; Hurley, Laurence H.

    2010-01-01

    In this review, the authors describe a novel mechanism for control of MYC expression that involves a four-stranded DNA structure, termed a G-quadruplex, amenable to small molecule targeting. The DNA element involved in this mechanism, the nuclease hypersensitive element III1 (NHE III1), is just upstream of the P1 promoter and is subjected to dynamic stress (negative superhelicity) resulting from transcription. This is sufficient to convert the duplex DNA to a G-quadruplex on the purine-rich strand and an i-motif of the pyrimidine-rich strand, which displaces the activating transcription factors to silence gene expression. Specific proteins have been identified, NM23-H2 and nucleolin, that resolve and fold the G-quadruplex to activate and silence MYC expression, respectively. Inhibition of the activity of NM23-H2 molecules that bind to the G-quadruplex silences gene expression, and redistribution of nucleolin from the nucleolus to the nucleoplasm is expected to inhibit MYC. The authors also describe the mechanism of action of Quarfloxin, a first-in-class G-quadruplex-interactive compound that involves the redistribution of nucleolin from the nucleolus to the nucleoplasm. G-quadruplexes have been best known as test-tube oddities for more than four decades. However, during the past decade, they have emerged as likely players in a number of important biological processes, including transcriptional control. Only time will tell if these odd DNA structures will assume the role of an established receptor class, but it is clear from the scientific literature that there is a dramatic increase in interest in this little-known area in the past few years. PMID:21113409

  19. MYC, Metabolic Synthetic Lethality, and Cancer.

    PubMed

    Hsieh, Annie L; Dang, Chi V

    2016-01-01

    The MYC oncogene plays a pivotal role in the development and progression of human cancers. It encodes a transcription factor that has broad reaching effects on many cellular functions, most importantly in driving cell growth through regulation of genes involved in ribosome biogenesis, metabolism, and cell cycle. Upon binding DNA with its partner MAX, MYC recruits factors that release paused RNA polymerases to drive transcription and amplify gene expression. At physiologic levels of MYC, occupancy of high-affinity DNA-binding sites drives 'house-keeping' metabolic genes and those involved in ribosome and mitochondrial biogenesis for biomass accumulation. At high oncogenic levels of MYC, invasion of low-affinity sites and enhancer sequences alter the transcriptome and cause metabolic imbalances, which activates stress response and checkpoints such as p53. Loss of checkpoints unleashes MYC's full oncogenic potential to couple metabolism with neoplastic cell growth and division. Cells that overexpress MYC, however, are vulnerable to metabolic perturbations that provide potential new avenues for cancer therapy. PMID:27557535

  20. The Guanine-Quadruplex Structure in the Human c-myc Gene's Promoter Is Converted into B-DNA Form by the Human Poly(ADP-Ribose)Polymerase-1

    PubMed Central

    Fekete, Anna; Kenesi, Erzsebet; Hunyadi-Gulyas, Eva; Durgo, Hajnalka; Berko, Barbara; Dunai, Zsuzsanna A.; Bauer, Pal I.

    2012-01-01

    The important regulatory role of the guanine-quadruplex (GQ) structure, present in the nuclease hypersensitive element (NHE) III1 region of the human c-myc (h c-myc) gene's promoter, in the regulation of the transcription of that gene has been documented. Here we present evidences, that the human nuclear poly(ADP-ribose)polymerase-1 (h PARP-1) protein participates in the regulation of the h c-myc gene expression through its interaction with this GQ structure, characterized by binding assays, fluorescence energy transfer (FRET) experiments and by affinity pull-down experiments in vitro, and by chromatin immunoprecipitation (ChIP)-qPCR analysis and h c-myc-promoter-luciferase reporter determinations in vivo. We surmise that h PARP-1 binds to the GQ structure and participates in the conversion of that structure into the transcriptionally more active B-DNA form. The first Zn-finger structure present in h PARP-1 participates in this interaction. PARP-1 might be a new member of the group of proteins participating in the regulation of transcription through their interactions with GQ structures present in the promoters of different genes. PMID:22880082

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

    PubMed Central

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

    2015-01-01

    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. PMID:26648259

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

    PubMed

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

    2016-04-20

    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

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

    PubMed Central

    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. Transcriptional Regulation of CRD-BP by c-myc

    PubMed Central

    Noubissi, Felicite K.; Nikiforov, Mikhail A.; Colburn, Nancy; Spiegelman, Vladimir S.

    2010-01-01

    The coding region determinant binding protein, CRD-BP, is a multifunctional RNA binding protein involved in different processes such as mRNA turnover, translation control, and localization. It is mostly expressed in fetal and neonatal tissues, where it regulates many transcripts essential for normal embryonic development. CRD-BP is scarce or absent in normal adult tissues but reactivated and/or overexpressed in various neoplastic and preneoplastic tumors and in most cell lines. Its expression has been associated with the most aggressive form of some cancers. CRD-BP is an important regulator of different genes including a variety of oncogenes or proto-oncogenes (c-myc, β-TrCP1, GLI1, etc.). Regulation of CRD-BP expression is critical for proper control of its targets as its overexpression may play an important role in abnormal cell proliferation, suppression of apoptosis, invasion, and metastasis. Molecular bases of the regulatory mechanisms governing CRD-BP expression are still not completely elucidated. In this article, we have identified c-myc as a novel transcriptional regulator of CRD-BP. We show that c-myc binds to CRD-BP promoter and induces its transcription. This induction of CRD-BP expression contributes to the role of c-myc in the regulation of translation, increase in cell size, and acceleration of cell cycle progression via a mechanism involving upregulation of β-TrCP1 levels and activities and accelerated degradation of PDCD4. PMID:21779431

  5. CCND2, CTNNB1, DDX3X, GLI2, SMARCA4, MYC, MYCN, PTCH1, TP53, and MLL2 gene variants and risk of childhood medulloblastoma.

    PubMed

    Dahlin, Anna M; Hollegaard, Mads V; Wibom, Carl; Andersson, Ulrika; Hougaard, David M; Deltour, Isabelle; Hjalmars, Ulf; Melin, Beatrice

    2015-10-01

    Recent studies have described a number of genes that are frequently altered in medulloblastoma tumors and that have putative key roles in the development of the disease. We hypothesized that common germline genetic variations in these genes may be associated with medulloblastoma development. Based on recent publications, we selected 10 genes that were frequently altered in medulloblastoma: CCND2, CTNNB1, DDX3X, GLI2, SMARCA4, MYC, MYCN, PTCH1, TP53, and MLL2 (now renamed as KMT2D). Common genetic variants (single nucleotide polymorphisms) annotating these genes (n = 221) were genotyped in germline DNA (neonatal dried blood spot samples) from 243 childhood medulloblastoma cases and 247 control subjects from Sweden and Denmark. Eight genetic variants annotating three genes in the sonic hedgehog signaling pathway; CCND2, PTCH1, and GLI2, were found to be associated with the risk of medulloblastoma (P(combined) < 0.05). The findings were however not statistically significant following correction for multiple testing by the very stringent Bonferroni method. The results do not support our hypothesis that common germline genetic variants in the ten studied genes are associated with the risk of developing medulloblastoma. PMID:26290144

  6. MYC, FBXW7 and TP53 copy number variation and expression in Gastric Cancer

    PubMed Central

    2013-01-01

    Background MYC deregulation is a common event in gastric carcinogenesis, usually as a consequence of gene amplification, chromosomal translocations, or posttranslational mechanisms. FBXW7 is a p53-controlled tumor-suppressor that plays a role in the regulation of cell cycle exit and reentry via MYC degradation. Methods We evaluated MYC, FBXW7, and TP53 copy number, mRNA levels, and protein expression in gastric cancer and paired non-neoplastic specimens from 33 patients and also in gastric adenocarcinoma cell lines. We also determined the invasion potential of the gastric cancer cell lines. Results MYC amplification was observed in 51.5% of gastric tumor samples. Deletion of one copy of FBXW7 and TP53 was observed in 45.5% and 21.2% of gastric tumors, respectively. MYC mRNA expression was significantly higher in tumors than in non-neoplastic samples. FBXW7 and TP53 mRNA expression was markedly lower in tumors than in paired non-neoplastic specimens. Moreover, deregulated MYC and FBXW7 mRNA expression was associated with the presence of lymph node metastasis and tumor stage III-IV. Additionally, MYC immunostaining was more frequently observed in intestinal-type than diffuse-type gastric cancers and was associated with MYC mRNA expression. In vitro studies showed that increased MYC and reduced FBXW7 expression is associated with a more invasive phenotype in gastric cancer cell lines. This result encouraged us to investigate the activity of the gelatinases MMP-2 and MMP-9 in both cell lines. Both gelatinases are synthesized predominantly by stromal cells rather than cancer cells, and it has been proposed that both contribute to cancer progression. We observed a significant increase in MMP-9 activity in ACP02 compared with ACP03 cells. These results confirmed that ACP02 cells have greater invasion capability than ACP03 cells. Conclusion In conclusion, FBXW7 and MYC mRNA may play a role in aggressive biologic behavior of gastric cancer cells and may be a useful

  7. Driven by the same Ig enhancer and SV40 T promoter ras induced lung adenomatous tumors, myc induced pre-B cell lymphomas and SV40 large T gene a variety of tumors in transgenic mice.

    PubMed Central

    Suda, Y; Aizawa, S; Hirai, S; Inoue, T; Furuta, Y; Suzuki, M; Hirohashi, S; Ikawa, Y

    1987-01-01

    Different types of tumors developed in transgenic mice following the introduction of the entire coding region of ras, myc or SV40 large T gene (T) linked to the same regulatory unit, consisting of a human immunoglobulin gene enhancer (Ig) and SV40 early gene promoter (Tp) with a 21-bp repeat. All the 12 transgenic mice harboring the intact T gene developed a variety of tumors including choroid plexus tumor, B cell lymphoma, histiocytic lymphoma, thymoma and others. This suggests that the Ig/Tp regulatory unit has transcriptional activity in these heterologous tissues. With this regulatory unit, myc gene induced solely pre-B cell lymphomas (five out of nine mice). Contrary to our expectation, however, the mutated ras gene induced lung adenomatous tumors in six out of eight transgenic mice over the 10-month observation period; the tumors are histologically comparable to adenocarcinomas in man. The tumors developed as early as 4 weeks after birth and the introduced ras gene was as efficiently expressed in both normal and neoplastic bronchioloalveolar epithelial cells as in normal lymphoid cells. An unidentified secondary event thus appears to be necessary for these ras-expressing cells to become neoplastic, as observed for myc (Leder et al., 1986). In a variety of tumors induced by Ig/Tp-T, on the other hand, T gene was expressed only in the tumor cells, but not in normal cells. Thus, derepression of T gene in normal cells appears to be closely related to their malignant change as observed in development of pancreatic acinar cell tumors by the T gene (Ornitz et al., 1985). These results suggest that ras and myc oncogenes penetrate differentially specific types of cells, while the SV40 T gene is tumorigenic in a variety of cell types. Images Fig. 3. Fig. 4. Fig. 5. Fig. 6. Fig. 7. PMID:2832150

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

    PubMed Central

    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

  9. The metastasis suppressor, N-myc downstream-regulated gene 1 (NDRG1), inhibits stress-induced autophagy in cancer cells.

    PubMed

    Sahni, Sumit; Bae, Dong-Hun; Lane, Darius J R; Kovacevic, Zaklina; Kalinowski, Danuta S; Jansson, Patric J; Richardson, Des R

    2014-04-01

    N-myc downstream regulated gene 1 (NDRG1) is a potent metastasis suppressor with an undefined role in the stress response. Autophagy is a pro-survival pathway and can be regulated via the protein kinase-like endoplasmic reticulum kinase (PERK)/eIF2α-mediated endoplasmic reticulum (ER) stress pathway. Hence, we investigated the role of NDRG1 in stress-induced autophagy as a mechanism of inhibiting metastasis via the induction of apoptosis. As thiosemicarbazone chelators induce stress and up-regulate NDRG1 to inhibit metastasis, we studied their effects on the ER stress response and autophagy. This was important to assess, as little is understood regarding the role of the stress induced by iron depletion and its role in autophagy. We observed that the chelator, di-2-pyridylketone 4,4-dimethyl-3-thiosemicarbazone (Dp44mT), which forms redox-active iron and copper complexes, effectively induced ER stress as shown by activation of the PERK/eIF2α pathway. Dp44mT also increased the expression of the autophagic marker, LC3-II, and this was dependent on activation of the PERK/eIF2α axis, as silencing PERK prevented LC3-II accumulation. The effect of Dp44mT on LC3-II expression was at least partially due to iron-depletion, as this effect was also demonstrated with the classical iron chelator, desferrioxamine (DFO), and was not observed for the DFO-iron complex. NDRG1 overexpression also inhibited basal autophagic initiation and the ER stress-mediated autophagic pathway via suppression of the PERK/eIF2α axis. Moreover, NDRG1-mediated suppression of the pro-survival autophagic pathway probably plays a role in its anti-metastatic effects by inducing apoptosis. In fact, multiple pro-apoptotic markers were increased, whereas anti-apoptotic Bcl-2 was decreased upon NDRG1 overexpression. This study demonstrates the role of NDRG1 as an autophagic inhibitor that is important for understanding its mechanism of action. PMID:24532803

  10. c-Myc alters substrate utilization and O-GlcNAc protein posttranslational modifications without altering cardiac function during early aortic constriction

    SciTech Connect

    Ledee, Dolena; Smith, Lincoln; Bruce, Margaret; Kajimoto, Masaki; Isern, Nancy; Portman, Michael A.; Olson, Aaron K.; Bertrand, Luc

    2015-08-12

    Pressure overload cardiac hypertrophy alters substrate metabolism. Prior work showed that myocardial inactivation of c-Myc (Myc) attenuated hypertrophy and decreased expression of metabolic 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 mice with cardiac specific, inducible Myc inactivation (MycKO-TAC) and non-transgenic littermates (Cont-TAC) to transverse aortic constriction (TAC; 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, ketone bodies and unlabeled glucose and insulin. 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 (predominately glucose) contribution. The changes in free fatty acid and unlabeled fractional contributions were abrogated by Myc inactivation during TAC (MycKO-TAC). Additionally, protein posttranslational modification by O-GlcNAc was significantly greater in Cont-TAC versus both Sham and MycKO-TAC. Lastly, Myc alters substrate preferences for the citric acid cycle during early pressure overload hypertrophy without negatively affecting cardiac function. Myc also affects protein posttranslational modifications by O-GlcNAc during hypertrophy.

  11. c-Myc alters substrate utilization and O-GlcNAc protein posttranslational modifications without altering cardiac function during early aortic constriction

    DOE PAGESBeta

    Ledee, Dolena; Smith, Lincoln; Bruce, Margaret; Kajimoto, Masaki; Isern, Nancy; Portman, Michael A.; Olson, Aaron K.; Bertrand, Luc

    2015-08-12

    Pressure overload cardiac hypertrophy alters substrate metabolism. Prior work showed that myocardial inactivation of c-Myc (Myc) attenuated hypertrophy and decreased expression of metabolic 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 mice with cardiac specific, inducible Myc inactivation (MycKO-TAC) and non-transgenic littermates (Cont-TAC) to transverse aortic constriction (TAC; n=7/group). A separate group underwent sham surgery (Sham, n=5). After two weeks, function was measured in isolated workingmore » hearts along with substrate fractional contributions to the citric acid cycle by using perfusate with 13C labeled mixed fatty acids, lactate, ketone bodies and unlabeled glucose and insulin. 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 (predominately glucose) contribution. The changes in free fatty acid and unlabeled fractional contributions were abrogated by Myc inactivation during TAC (MycKO-TAC). Additionally, protein posttranslational modification by O-GlcNAc was significantly greater in Cont-TAC versus both Sham and MycKO-TAC. Lastly, Myc alters substrate preferences for the citric acid cycle during early pressure overload hypertrophy without negatively affecting cardiac function. Myc also affects protein posttranslational modifications by O-GlcNAc during hypertrophy.« less

  12. mSin3A/Histone Deacetylase 2- and PRMT5-Containing Brg1 Complex Is Involved in Transcriptional Repression of the Myc Target Gene cad

    PubMed Central

    Pal, Sharmistha; Yun, Romy; Datta, Antara; Lacomis, Lynne; Erdjument-Bromage, Hediye; Kumar, Jitendra; Tempst, Paul; Sif, Saïd

    2003-01-01

    The role of hSWI/SNF complexes in transcriptional activation is well characterized; however, little is known about their function in transcriptional repression. We have previously shown that subunits of the mSin3A/histone deacetylase 2 (HDAC2) corepressor complex copurify with hSWI/SNF complexes. Here we show that the type II arginine-specific methyltransferase PRMT5, which is involved in cyclin E repression, can be found in association with Brg1 and hBrm-based hSWI/SNF complexes. We also show that hSWI/SNF-associated PRMT5 can methylate hypoacetylated histones H3 and H4 more efficiently than hyperacetylated histones H3 and H4. Protein-protein interaction studies indicate that PRMT5 and mSin3A interact with the same hSWI/SNF subunits as those targeted by c-Myc. These observations prompted us to examine the expression profile of the c-Myc target genes, carbamoyl-phosphate synthase-aspartate carbamoyltransferase-dihydroorotase (cad) and nucleolin (nuc). We found that cad repression is altered in cells that express inactive Brg1 and in cells treated with the HDAC inhibitor depsipeptide. Using chromatin immunoprecipitation assays, we found that Brg1, mSin3A, HDAC2, and PRMT5 are directly recruited to the cad promoter. These results suggest that hSWI/SNF complexes, through their ability to interact with activator and repressor proteins, control expression of genes involved in cell growth and proliferation. PMID:14559996

  13. MYC activation and BCL2L11 silencing by a tumour virus through the large-scale reconfiguration of enhancer-promoter hubs

    PubMed Central

    Wood, C David; Veenstra, Hildegonda; Khasnis, Sarika; Gunnell, Andrea; Webb, Helen M; Shannon-Lowe, Claire; Andrews, Simon; Osborne, Cameron S; West, Michelle J

    2016-01-01

    Lymphomagenesis in the presence of deregulated MYC requires suppression of MYC-driven apoptosis, often through downregulation of the pro-apoptotic BCL2L11 gene (Bim). Transcription factors (EBNAs) encoded by the lymphoma-associated Epstein-Barr virus (EBV) activate MYC and silence BCL2L11. We show that the EBNA2 transactivator activates multiple MYC enhancers and reconfigures the MYC locus to increase upstream and decrease downstream enhancer-promoter interactions. EBNA2 recruits the BRG1 ATPase of the SWI/SNF remodeller to MYC enhancers and BRG1 is required for enhancer-promoter interactions in EBV-infected cells. At BCL2L11, we identify a haematopoietic enhancer hub that is inactivated by the EBV repressors EBNA3A and EBNA3C through recruitment of the H3K27 methyltransferase EZH2. Reversal of enhancer inactivation using an EZH2 inhibitor upregulates BCL2L11 and induces apoptosis. EBV therefore drives lymphomagenesis by hijacking long-range enhancer hubs and specific cellular co-factors. EBV-driven MYC enhancer activation may contribute to the genesis and localisation of MYC-Immunoglobulin translocation breakpoints in Burkitt's lymphoma. DOI: http://dx.doi.org/10.7554/eLife.18270.001 PMID:27490482

  14. MYC activation and BCL2L11 silencing by a tumour virus through the large-scale reconfiguration of enhancer-promoter hubs.

    PubMed

    Wood, C David; Veenstra, Hildegonda; Khasnis, Sarika; Gunnell, Andrea; Webb, Helen M; Shannon-Lowe, Claire; Andrews, Simon; Osborne, Cameron S; West, Michelle J

    2016-01-01

    Lymphomagenesis in the presence of deregulated MYC requires suppression of MYC-driven apoptosis, often through downregulation of the pro-apoptotic BCL2L11 gene (Bim). Transcription factors (EBNAs) encoded by the lymphoma-associated Epstein-Barr virus (EBV) activate MYC and silence BCL2L11. We show that the EBNA2 transactivator activates multiple MYC enhancers and reconfigures the MYC locus to increase upstream and decrease downstream enhancer-promoter interactions. EBNA2 recruits the BRG1 ATPase of the SWI/SNF remodeller to MYC enhancers and BRG1 is required for enhancer-promoter interactions in EBV-infected cells. At BCL2L11, we identify a haematopoietic enhancer hub that is inactivated by the EBV repressors EBNA3A and EBNA3C through recruitment of the H3K27 methyltransferase EZH2. Reversal of enhancer inactivation using an EZH2 inhibitor upregulates BCL2L11 and induces apoptosis. EBV therefore drives lymphomagenesis by hijacking long-range enhancer hubs and specific cellular co-factors. EBV-driven MYC enhancer activation may contribute to the genesis and localisation of MYC-Immunoglobulin translocation breakpoints in Burkitt's lymphoma. PMID:27490482

  15. The Caenorhabditis elegans Myc-Mondo/Mad Complexes Integrate Diverse Longevity Signals

    PubMed Central

    Johnson, David W.; Llop, Jesse R.; Farrell, Sara F.; Yuan, Jie; Stolzenburg, Lindsay R.; Samuelson, Andrew V.

    2014-01-01

    The Myc family of transcription factors regulates a variety of biological processes, including the cell cycle, growth, proliferation, metabolism, and apoptosis. In Caenorhabditis elegans, the “Myc interaction network” consists of two opposing heterodimeric complexes with antagonistic functions in transcriptional control: the Myc-Mondo:Mlx transcriptional activation complex and the Mad:Max transcriptional repression complex. In C. elegans, Mondo, Mlx, Mad, and Max are encoded by mml-1, mxl-2, mdl-1, and mxl-1, respectively. Here we show a similar antagonistic role for the C. elegans Myc-Mondo and Mad complexes in longevity control. Loss of mml-1 or mxl-2 shortens C. elegans lifespan. In contrast, loss of mdl-1 or mxl-1 increases longevity, dependent upon MML-1:MXL-2. The MML-1:MXL-2 and MDL-1:MXL-1 complexes function in both the insulin signaling and dietary restriction pathways. Furthermore, decreased insulin-like/IGF-1 signaling (ILS) or conditions of dietary restriction increase the accumulation of MML-1, consistent with the notion that the Myc family members function as sensors of metabolic status. Additionally, we find that Myc family members are regulated by distinct mechanisms, which would allow for integrated control of gene expression from diverse signals of metabolic status. We compared putative target genes based on ChIP-sequencing data in the modENCODE project and found significant overlap in genomic DNA binding between the major effectors of ILS (DAF-16/FoxO), DR (PHA-4/FoxA), and Myc family (MDL-1/Mad/Mxd) at common target genes, which suggests that diverse signals of metabolic status converge on overlapping transcriptional programs that influence aging. Consistent with this, there is over-enrichment at these common targets for genes that function in lifespan, stress response, and carbohydrate metabolism. Additionally, we find that Myc family members are also involved in stress response and the maintenance of protein homeostasis. Collectively

  16. The c-MYC Protooncogene Expression in Cholesteatoma

    PubMed Central

    Palkó, Enikő; Póliska, Szilárd; Csákányi, Zsuzsanna; Katona, Gábor; Karosi, Tamás; Penyige, András; Sziklai, István

    2014-01-01

    Cholesteatoma is an epidermoid cyst, which is most frequently found in the middle ear. The matrix of cholesteatoma is histologically similar to the matrix of the epidermoid cyst of the skin (atheroma); their epithelium is characterized by hyperproliferation. The c-MYC protooncogene located on chromosome 8q24 encodes a transcription factor involved in the regulation of cell proliferation and differentiation. Previous studies have found aneuploidy of chromosome 8, copy number variation of c-MYC gene, and the presence of elevated level c-MYC protein in cholesteatoma. In this study we have compared the expression of c-MYC gene in samples taken from the matrix of 26 acquired cholesteatomas (15 children and 11 adults), 15 epidermoid cysts of the skin (atheromas; head and neck region) and 5 normal skin samples (retroauricular region) using RT-qPCR, providing the first precise measurement of the expression of c-MYC gene in cholesteatoma. We have found significantly elevated c-MYC gene expression in cholesteatoma compared to atheroma and to normal skin samples. There was no significant difference, however, in c-MYC gene expression between cholesteatoma samples of children and adults. The significant difference in c-MYC gene expression level in cholesteatoma compared to that of atheroma implies a more prominent hyperproliferative phenotype which may explain the clinical behavior typical of cholesteatoma. PMID:24683550

  17. Ribosomal protein S14 negatively regulates c-Myc activity.

    PubMed

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

    2013-07-26

    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

  18. The Quest for Targets Executing MYC-Dependent Cell Transformation.

    PubMed

    Hartl, Markus

    2016-01-01

    MYC represents a transcription factor with oncogenic potential converting multiple cellular signals into a broad transcriptional response, thereby controlling the expression of numerous protein-coding and non-coding RNAs important for cell proliferation, metabolism, differentiation, and apoptosis. Constitutive activation of MYC leads to neoplastic cell transformation, and deregulated MYC alleles are frequently observed in many human cancer cell types. Multiple approaches have been performed to isolate genes differentially expressed in cells containing aberrantly activated MYC proteins leading to the identification of thousands of putative targets. Functional analyses of genes differentially expressed in MYC-transformed cells had revealed that so far more than 40 upregulated or downregulated MYC targets are actively involved in cell transformation or tumorigenesis. However, further systematic and selective approaches are required for determination of the known or yet unidentified targets responsible for processing the oncogenic MYC program. The search for critical targets in MYC-dependent tumor cells is exacerbated by the fact that during tumor development, cancer cells progressively evolve in a multistep process, thereby acquiring their characteristic features in an additive manner. Functional expression cloning, combinatorial gene expression, and appropriate in vivo tests could represent adequate tools for dissecting the complex scenario of MYC-specified cell transformation. In this context, the central goal is to identify a minimal set of targets that suffices to phenocopy oncogenic MYC. Recently developed genomic editing tools could be employed to confirm the requirement of crucial transformation-associated targets. Knowledge about essential MYC-regulated genes is beneficial to expedite the development of specific inhibitors to interfere with growth and viability of human tumor cells in which MYC is aberrantly activated. Approaches based on the principle of

  19. The Quest for Targets Executing MYC-Dependent Cell Transformation

    PubMed Central

    Hartl, Markus

    2016-01-01

    MYC represents a transcription factor with oncogenic potential converting multiple cellular signals into a broad transcriptional response, thereby controlling the expression of numerous protein-coding and non-coding RNAs important for cell proliferation, metabolism, differentiation, and apoptosis. Constitutive activation of MYC leads to neoplastic cell transformation, and deregulated MYC alleles are frequently observed in many human cancer cell types. Multiple approaches have been performed to isolate genes differentially expressed in cells containing aberrantly activated MYC proteins leading to the identification of thousands of putative targets. Functional analyses of genes differentially expressed in MYC-transformed cells had revealed that so far more than 40 upregulated or downregulated MYC targets are actively involved in cell transformation or tumorigenesis. However, further systematic and selective approaches are required for determination of the known or yet unidentified targets responsible for processing the oncogenic MYC program. The search for critical targets in MYC-dependent tumor cells is exacerbated by the fact that during tumor development, cancer cells progressively evolve in a multistep process, thereby acquiring their characteristic features in an additive manner. Functional expression cloning, combinatorial gene expression, and appropriate in vivo tests could represent adequate tools for dissecting the complex scenario of MYC-specified cell transformation. In this context, the central goal is to identify a minimal set of targets that suffices to phenocopy oncogenic MYC. Recently developed genomic editing tools could be employed to confirm the requirement of crucial transformation-associated targets. Knowledge about essential MYC-regulated genes is beneficial to expedite the development of specific inhibitors to interfere with growth and viability of human tumor cells in which MYC is aberrantly activated. Approaches based on the principle of

  20. MYC Cofactors: Molecular Switches Controlling Diverse Biological Outcomes

    PubMed Central

    Hann, Stephen R.

    2014-01-01

    The transcription factor MYC has fundamental roles in proliferation, apoptosis, tumorigenesis, and stem cell pluripotency. Over the last 30 years extensive information has been gathered on the numerous cofactors that interact with MYC and the target genes that are regulated by MYC as a means of understanding the molecular mechanisms controlling its diverse roles. Despite significant advances and perhaps because the amount of information learned about MYC is overwhelming, there has been little consensus on the molecular functions of MYC that mediate its critical biological roles. In this perspective, the major MYC cofactors that regulate the various transcriptional activities of MYC, including canonical and noncanonical transactivation and transcriptional repression, will be reviewed and a model of how these transcriptional mechanisms control MYC-mediated proliferation, apoptosis, and tumorigenesis will be presented. The basis of the model is that a variety of cofactors form dynamic MYC transcriptional complexes that can switch the molecular and biological functions of MYC to yield a diverse range of outcomes in a cell-type- and context-dependent fashion. PMID:24939054

  1. Positive regulation of c-Myc by cohesin is direct, and evolutionarily conserved

    PubMed Central

    Rhodes, Jenny M.; Bentley, Fiona K.; Print, Cristin G.; Dorsett, Dale; Misulovin, Ziva; Dickinson, Emma J.; Crosier, Kathryn E.; Crosier, Philip S.; Horsfield, Julia A.

    2010-01-01

    Contact between sister chromatids from S phase to anaphase depends on cohesin, a large multi-subunit protein complex. Mutations in sister chromatid cohesion proteins underlie the human developmental condition, Cornelia de Lange Syndrome. Roles for cohesin in regulating gene expression, sometimes in combination with CCCTC-binding factor (CTCF), have emerged. We analyzed zebrafish embryos null for cohesin subunit rad21 using microarrays to determine global effects of cohesin on gene expression during embryogenesis. This identified Rad21-associated gene networks that included myca (zebrafish c-myc), p53 and mdm2. In zebrafish, cohesin binds to the transcription start sites of p53 and mdm2, and depletion of either Rad21 or CTCF increased their transcription. In contrast, myca expression was strongly downregulated upon loss of Rad21 while depletion of CTCF had little effect. Depletion of Rad21 or the cohesin-loading factor Nipped-B in Drosophila cells also reduced expression of myc and Myc target genes. Cohesin bound the transcription start site plus an upstream predicted CTCF binding site at zebrafish myca. Binding and positive regulation of the c-Myc gene by cohesin is conserved through evolution, indicating this regulation is likely to be direct. The exact mechanism of regulation is unknown, but local changes in histone modification associated with transcription repression at the myca gene were observed in rad21 mutants. PMID:20553708

  2. Targeting ornithine decarboxylase in Myc-induced lymphomagenesis prevents tumor formation.

    PubMed

    Nilsson, Jonas A; Keller, Ulrich B; Baudino, Troy A; Yang, Chunying; Norton, Sara; Old, Jennifer A; Nilsson, Lisa M; Neale, Geoffrey; Kramer, Debora L; Porter, Carl W; Cleveland, John L

    2005-05-01

    Checkpoints that control Myc-mediated proliferation and apoptosis are bypassed during tumorigenesis. Genes encoding polyamine biosynthetic enzymes are overexpressed in B cells from E mu-Myc transgenic mice. Here, we report that disabling one of these Myc targets, Ornithine decarboxylase (Odc), abolishes Myc-induced suppression of the Cdk inhibitors p21(Cip1) and p27(Kip1), thereby impairing Myc's proliferative, but not apoptotic, response. Moreover, lymphoma development was markedly delayed in E mu-Myc;Odc(+/-) transgenic mice and in E mu-Myc mice treated with the Odc inhibitor difluoromethylornithine (DFMO). Strikingly, tumors ultimately arising in E mu-Myc;Odc(+/-) transgenics lacked deletions of Arf, suggesting that targeting Odc forces other routes of transformation. Therefore, Odc is a critical Myc transcription target that regulates checkpoints that guard against tumorigenesis and is an effective target for cancer chemoprevention. PMID:15894264

  3. LncRNA-MIF, a c-Myc-activated long non-coding RNA, suppresses glycolysis by promoting Fbxw7-mediated c-Myc degradation.

    PubMed

    Zhang, Pengfei; Cao, Limian; Fan, Pingsheng; Mei, Yide; Wu, Mian

    2016-08-01

    The c-Myc proto-oncogene is activated in more than half of all human cancers. However, the precise regulation of c-Myc protein stability is unknown. Here, we show that the lncRNA-MIF (c-Myc inhibitory factor), a c-Myc-induced long non-coding RNA, is a competing endogenous RNA for miR-586 and attenuates the inhibitory effect of miR-586 on Fbxw7, an E3 ligase for c-Myc, leading to increased Fbxw7 expression and subsequent c-Myc degradation. Our data reveal the existence of a feedback loop between c-Myc and lncRNA-MIF, through which c-Myc protein stability is finely controlled. Additionally, we show that the lncRNA-MIF inhibits aerobic glycolysis and tumorigenesis by suppressing c-Myc and miR-586. PMID:27317567

  4. In a model of immunoglobulin heavy-chain (IGH)/MYC translocation, the Igh 3' regulatory region induces MYC expression at the immature stage of B cell development.

    PubMed

    Yan, Yi; Park, Sung Sup; Janz, Siegfried; Eckhardt, Laurel A

    2007-10-01

    Reciprocal translocations involving the immunoglobulin loci and the cellular oncogene MYC are hallmark mutations of the human postgerminal center B cell neoplasm, Burkitt's lymphoma. They are occasionally found in other B cell lymphomas, as well. Translocations involving the heavy chain locus (IGH) place the MYC gene either in cis with both the intronic enhancer Emu and the IGH 3' regulatory region (3'RR) or in cis with only the 3'RR. The result is deregulated MYC expression. Recent studies have led to some controversy as to when, during B lymphocyte development, IGH/MYC chromosome translocations take place. A related issue, relevant not only to lymphoma development but also to normal controls on IGH gene expression, is the stage, during B lymphocyte development, at which the 3'RR is capable of activating MYC expression. We have developed mice transgenic for a human MYC (hMYC) gene under control of the four core enhancers from the mouse Igh 3'RR. Unlike other transgenic mouse models where premature and inappropriate MYC expression disrupts normal B cell development, the hMYC transgene in these studies carries a mutation that prohibits MYC protein synthesis. As a result, hMYC expression can be analyzed in all of the normal B cell compartments. Our data show that hMYC is expressed almost exclusively in B-lineage cells and is induced to high levels as soon as bone marrow cells reach the immature B cell stage. PMID:17639584

  5. Mouse Genetics Suggests Cell-Context Dependency for Myc-Regulated Metabolic Enzymes during Tumorigenesis

    PubMed Central

    Nilsson, Lisa M.; Kreutzer, Christiane; Pretsch, Walter; Bornkamm, Georg W.; Nilsson, Jonas A.

    2012-01-01

    c-Myc (hereafter called Myc) belongs to a family of transcription factors that regulates cell growth, cell proliferation, and differentiation. Myc initiates the transcription of a large cast of genes involved in cell growth by stimulating metabolism and protein synthesis. Some of these, like those involved in glycolysis, may be part of the Warburg effect, which is defined as increased glucose uptake and lactate production in the presence of adequate oxygen supply. In this study, we have taken a mouse-genetics approach to challenge the role of select Myc-regulated metabolic enzymes in tumorigenesis in vivo. By breeding λ-Myc transgenic mice, ApcMin mice, and p53 knockout mice with mouse models carrying inactivating alleles of Lactate dehydrogenase A (Ldha), 3-Phosphoglycerate dehydrogenase (Phgdh) and Serine hydroxymethyltransferase 1 (Shmt1), we obtained offspring that were monitored for tumor development. Very surprisingly, we found that these genes are dispensable for tumorigenesis in these genetic settings. However, experiments in fibroblasts and colon carcinoma cells expressing oncogenic Ras show that these cells are sensitive to Ldha knockdown. Our genetic models reveal cell context dependency and a remarkable ability of tumor cells to adapt to alterations in critical metabolic pathways. Thus, to achieve clinical success, it will be of importance to correctly stratify patients and to find synthetic lethal combinations of inhibitors targeting metabolic enzymes. PMID:22438825

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

    NASA Astrophysics Data System (ADS)

    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.

  7. Insulin-like growth factor II blocks apoptosis of N-myc2-expressing woodchuck liver epithelial cells.

    PubMed Central

    Yang, D; Faris, R; Hixson, D; Affigne, S; Rogler, C E

    1996-01-01

    N-myc2 and insulin-like growth factor II (IGF-II) are coordinately overexpressed in the great majority of altered hepatic foci, which are the earliest precancerous lesions observed in the liver of woodchuck hepatitis virus carrier woodchucks, and these genes continue to be overexpressed in hepatocellular carcinomas (HCCs). We have investigated the function of these genes in woodchuck hepatocarcinogenesis by using a woodchuck liver epithelial cell line (WC-3). WC-3 cells react positively with a monoclonal antibody (12.8.5) against woodchuck oval cells, suggesting a lineage relationship with oval cells. Overexpression of N-myc2 in three WC-3 cell lines caused their morphological transformation and increased their growth rate and saturation density in medium containing 10% serum. Removal of serum from the medium increased cell death of the N-myc2-expressing lines, whereas cell death in control lines was minimal. The death of N-myc2-expressing WC-3 cells was accompanied by nucleosomal fragmentation of cellular DNA, and DAPI (4',6-diamidino-2-phenylindole) staining revealed condensation and fragmentation of the nuclei, suggesting that N-myc2-expressing WC-3 cells undergo apoptosis in the absence of serum. In colony regression assays, conducted in the absence of serum, control colonies were stable, while N-myc2-expressing colonies regressed to various degrees. Addition of recombinant human IGF-II to the serum-free medium blocked both cell death and colony regression in all the N-myc2-expressing lines. Therefore, coordinate overexpression of N-myc2 and IGF-II in woodchuck altered hepatic foci may allow cells which otherwise might die to survive and progress to hepatocellular carcinoma. PMID:8709253

  8. Myc Potentiates Apoptosis by Stimulating Bax Activity at the Mitochondria†

    PubMed Central

    Soucie, Erinn L.; Annis, Matthew G.; Sedivy, John; Filmus, Jorge; Leber, Brian; Andrews, David W.; Penn, Linda Z.

    2001-01-01

    The ability of the c-Myc oncoprotein to potentiate apoptosis has been well documented; however, the mechanism of action remains ill defined. We have previously identified spatially distinct apoptotic pathways within the same cell that are differentially inhibited by Bcl-2 targeted to either the mitochondria (Bcl-acta) or the endoplasmic reticulum (Bcl-cb5). We show here that in Rat1 cells expressing an exogenous c-myc allele, distinct apoptotic pathways can be inhibited by Bcl-2 or Bcl-acta yet be distinguished by their sensitivity to Bcl-cb5 as either susceptible (serum withdrawal, taxol, and ceramide) or refractory (etoposide and doxorubicin). Myc expression and apoptosis were universally associated with Bcl-acta and not Bcl-cb5, suggesting that Myc acts downstream at a point common to these distinct apoptotic signaling cascades. Analysis of Rat1 c-myc null cells shows these same death stimuli induce apoptosis with characteristic features of nuclear condensation, membrane blebbing, poly (ADP-ribose) polymerase cleavage, and DNA fragmentation; however, this Myc-independent apoptosis is not inhibited by Bcl-2. During apoptosis, Bax translocation to the mitochondria occurs in the presence or absence of Myc expression. Moreover, Bax mRNA and protein expression remain unchanged in the presence or absence of Myc. However, in the absence of Myc, Bax is not activated and cytochrome c is not released into the cytoplasm. Reintroduction of Myc into the c-myc null cells restores Bax activation, cytochrome c release, and inhibition of apoptosis by Bcl-2. These results demonstrate a role for Myc in the regulation of Bax activation during apoptosis. Moreover, apoptosis that can be triggered in the absence of Myc provides evidence that signaling pathways exist which circumvent Bax activation and cytochrome c release to trigger caspase activation. Thus, Myc increases the cellular competence to die by enhancing disparate apoptotic signals at a common mitochondrial amplification

  9. Interaction of MYC with host cell factor-1 is mediated by the evolutionarily conserved Myc box IV motif.

    PubMed

    Thomas, L R; Foshage, A M; Weissmiller, A M; Popay, T M; Grieb, B C; Qualls, S J; Ng, V; Carboneau, B; Lorey, S; Eischen, C M; Tansey, W P

    2016-07-01

    The MYC family of oncogenes encodes a set of three related transcription factors that are overexpressed in many human tumors and contribute to the cancer-related deaths of more than 70,000 Americans every year. MYC proteins drive tumorigenesis by interacting with co-factors that enable them to regulate the expression of thousands of genes linked to cell growth, proliferation, metabolism and genome stability. One effective way to identify critical co-factors required for MYC function has been to focus on sequence motifs within MYC that are conserved throughout evolution, on the assumption that their conservation is driven by protein-protein interactions that are vital for MYC activity. In addition to their DNA-binding domains, MYC proteins carry five regions of high sequence conservation known as Myc boxes (Mb). To date, four of the Mb motifs (MbI, MbII, MbIIIa and MbIIIb) have had a molecular function assigned to them, but the precise role of the remaining Mb, MbIV, and the reason for its preservation in vertebrate Myc proteins, is unknown. Here, we show that MbIV is required for the association of MYC with the abundant transcriptional coregulator host cell factor-1 (HCF-1). We show that the invariant core of MbIV resembles the tetrapeptide HCF-binding motif (HBM) found in many HCF-interaction partners, and demonstrate that MYC interacts with HCF-1 in a manner indistinguishable from the prototypical HBM-containing protein VP16. Finally, we show that rationalized point mutations in MYC that disrupt interaction with HCF-1 attenuate the ability of MYC to drive tumorigenesis in mice. Together, these data expose a molecular function for MbIV and indicate that HCF-1 is an important co-factor for MYC. PMID:26522729

  10. MYC protein expression and genetic alterations have prognostic impact in patients with diffuse large B-cell lymphoma treated with immunochemotherapy

    PubMed Central

    Valera, Alexandra; López-Guillermo, Armando; Cardesa-Salzmann, Teresa; Climent, Fina; González-Barca, Eva; Mercadal, Santiago; Espinosa, Íñigo; Novelli, Silvana; Briones, Javier; Mate, José L.; Salamero, Olga; Sancho, Juan M.; Arenillas, Leonor; Serrano, Sergi; Erill, Nadina; Martínez, Daniel; Castillo, Paola; Rovira, Jordina; Martínez, Antonio; Campo, Elias; Colomo, Luis

    2013-01-01

    MYC alterations influence the survival of patients with diffuse large B-cell lymphoma. Most studies have focused on MYC translocations but there is little information regarding the impact of numerical alterations and protein expression. We analyzed the genetic alterations and protein expression of MYC, BCL2, BCL6, and MALT1 in 219 cases of diffuse large B-cell lymphoma. MYC rearrangement occurred as the sole abnormality (MYC single-hit) in 3% of cases, MYC and concurrent BCL2 and/or BCL6 rearrangements (MYC double/triple-hit) in 4%, MYC amplifications in 2% and MYC gains in 19%. MYC single-hit, MYC double/triple-hit and MYC amplifications, but not MYC gains or other gene rearrangements, were associated with unfavorable progression-free survival and overall survival. MYC protein expression, evaluated using computerized image analysis, captured the unfavorable prognosis of MYC translocations/amplifications and identified an additional subset of patients without gene alterations but with similar poor prognosis. Patients with tumors expressing both MYC/BCL2 had the worst prognosis, whereas those with double-negative tumors had the best outcome. High MYC expression was associated with shorter overall survival irrespectively of the International Prognostic Index and BCL2 expression. In conclusion, MYC protein expression identifies a subset of diffuse large B-cell lymphoma with very poor prognosis independently of gene alterations and other prognostic parameters. PMID:23716551

  11. Synergistic efficacy of sorafenib and genistein in growth inhibition by down regulating angiogenic and survival factors and increasing apoptosis through upregulation of p53 and p21 in malignant neuroblastoma cells having N-Myc amplification or non-amplification.

    PubMed

    Roy Choudhury, Subhasree; Karmakar, Surajit; Banik, Naren L; Ray, Swapan K

    2010-12-01

    Neuroblastoma is an extracranial, solid, and heterogeneous malignancy in children. The conventional therapeutic modalities are mostly ineffective and thus new therapeutic strategies for malignant neuroblastoma are urgently warranted. We examined the synergistic efficacy of combination of sorafenib (SF) and genistein (GST) in human malignant neuroblastoma SK-N-DZ (N-Myc amplified) and SH-SY5Y (N-Myc non-amplified) cell lines. MTT assay showed dose-dependent decrease in cell viability and the combination therapy more prominently inhibited the cell proliferation in both cell lines than either treatment alone. Apoptosis was confirmed morphologically by Wright staining. Flow cytometric analysis of cell cycle phase distribution and Annexin V-FITC/PI staining showed increase in subG1 DNA content and early apoptosis, respectively, after treatment with the combination of drugs. Apoptosis was further confirmed by scanning electron microscopy. Combination therapy showed activation of caspase-8, cleavage of Bid to tBid, increase in p53 and p21 expression, down regulation of anti-apoptotic Mcl-1, and increase in Bax:Bcl-2 ratio to trigger apoptosis. Down regulation of MDR, hTERT, N-Myc, VEGF, FGF-2, NF-κB, p-Akt, and c-IAP2 indicated suppression of angiogenic and survival pathways. Mitochondrial release of cytochrome c and Smac into cytosol indicated involvement of mitochondia in apoptosis. Increases in proteolytic activities of calpain and caspase-3 were also confirmed. Our results suggested that combination of SF and GST inhibited angiogenic and survival factors and increased apoptosis via receptor and mitochondria mediated pathways in both neuroblastoma SK-N-DZ and SH-SY5Y cell lines. Thus, this combination of drugs could be a potential therapeutic strategy against human malignant neuroblastoma cells having N-Myc amplification or non-amplification. PMID:19777160

  12. Prognostic and Predictive Significance of MYC and KRAS Alterations in Breast Cancer from Women Treated with Neoadjuvant Chemotherapy

    PubMed Central

    de Souza, Carolina Rosal Teixeira; Montenegro, Raquel Carvalho; Rey, Juan Antonio; Carvalho, Antônio Alberto; Assumpção, Paulo Pimentel; Khayat, André Salim; Pinto, Giovanny Rebouças; Demachki, Sâmia; de Arruda Cardoso Smith, Marília; Burbano, Rommel Rodríguez

    2013-01-01

    Breast cancer is a complex disease, with heterogeneous clinical evolution. Several analyses have been performed to identify the risk factors for breast cancer progression and the patients who respond best to a specific treatment. We aimed to evaluate whether the hormone receptor expression, HER2 and MYC genes and their protein status, and KRAS codon 12 mutations may be prognostic or predictive biomarkers of breast cancer. Protein, gene and mutation status were concomitantly evaluated in 116 breast tumors from women who underwent neoadjuvant chemotherapy with doxorubicin plus cyclophosphamide. We observed that MYC expression was associated with luminal B and HER2 overexpression phenotypes compared to luminal A (p<0.05). The presence of MYC duplication or polysomy 8, as well as KRAS mutation, were also associated with the HER2 overexpression subtype (p<0.05). MYC expression and MYC gain were more frequently observed in early-onset compared to late-onset tumors (p<0.05). KRAS mutation was a risk factor of grade 3 tumors (p<0.05). A multivariate logistic regression demonstrated that MYC amplification defined as MYC/nucleus ratio of ≥2.5 was a protective factor for chemotherapy resistance. On the other hand, age and grade 2 tumors were a risk factor. Additionally, luminal B, HER2 overexpression, and triple-negative tumors presented increased odds of being resistant to chemotherapy relative to luminal A tumors. Thus, breast tumors with KRAS codon 12 mutations seem to present a worse prognosis. Additionally, MYC amplification may help in the identification of tumors that are sensitive to doxorubicin plus cyclophosphamide treatment. If confirmed in a large set of samples, these markers may be useful for clinical stratification and prognosis. PMID:23555992

  13. MYC and Mitochondrial Biogenesis

    PubMed Central

    Morrish, Fionnuala; Hockenbery, David

    2014-01-01

    Mitochondria, the powerhouses of the cell, face two imperatives concerning biogenesis. The first is the requirement for dividing cells to replicate their mitochondrial content by growth of existing mitochondria. The second is the dynamic regulation of mitochondrial content in response to organismal and cellular cues (e.g., exercise, caloric restriction, energy status, temperature). MYC provides the clearest example of a programmed expansion of mitochondrial content linked to the cell cycle. As an oncogene, MYC also presents intriguing questions about the role of its mitochondrial targets in cancer-related phenotypes, such as the Warburg effect and MYC-dependent apoptosis. PMID:24789872

  14. Function of Cytochrome P450 Enzymes MycCI and MycG in Micromonospora griseorubida, a Producer of the Macrolide Antibiotic Mycinamicin

    PubMed Central

    Tsukada, Shu-ichi; Sakai, Ayami; Masuda, Ryohei; Harada, Chie; Domeki, Ayaka; Li, Shengying; Kinoshita, Kenji; Sherman, David H.; Kato, Fumio

    2012-01-01

    The cytochrome P450 enzymes MycCI and MycG are encoded within the mycinamicin biosynthetic gene cluster and are involved in the biosynthesis of mycinamicin II (a 16-membered macrolide antibiotic produced by Micromonospora griseorubida). Based on recent enzymatic studies, MycCI is characterized as the C-21 methyl hydroxylase of mycinamicin VIII, while MycG is designated multifunctional P450, which catalyzes hydroxylation and also epoxidation at C-14 and C-12/13 on the macrolactone ring of mycinamicin. Here, we confirm the functions of MycCI and MycG in M. griseorubida. Protomycinolide IV and mycinamicin VIII accumulated in the culture broth of the mycCI disruption mutant; moreover, the mycCI gene fragment complemented the production of mycinamicin I and mycinamicin II, which are produced as major mycinamicins by the wild strain M. griseorubida A11725. The mycG disruption mutant did not produce mycinamicin I and mycinamicin II; however, mycinamicin IV accumulated in the culture broth. The mycG gene was located immediately downstream of the self-resistance gene myrB. The mycG gene under the control of mycGp complemented the production of mycinamicin I and mycinamicin II. Furthermore, the amount of mycinamicin II produced by the strain complemented with the mycG gene under the control of myrBp was approximately 2-fold higher than that produced by the wild strain. In M. griseorubida, MycG recognized mycinamicin IV, mycinamicin V, and also mycinamicin III as the substrates. Moreover, it catalyzed hydroxylation and also epoxidation at C-14 and C-12/13 on these intermediates. However, C-14 on mycinamicin I was not hydroxylated. PMID:22547618

  15. Metabolic reprogramming in triple-negative breast cancer through Myc suppression of TXNIP

    PubMed Central

    Shen, Liangliang; O’Shea, John M.; Kaadige, Mohan R.; Cunha, Stéphanie; Wilde, Blake R.; Cohen, Adam L.; Welm, Alana L.; Ayer, Donald E.

    2015-01-01

    Triple-negative breast cancers (TNBCs) are aggressive and lack targeted therapies. Understanding how nutrients are used in TNBCs may provide new targets for therapeutic intervention. We demonstrate that the transcription factor c-Myc drives glucose metabolism in TNBC cells but does so by a previously unappreciated mechanism that involves direct repression of thioredoxin-interacting protein (TXNIP). TXNIP is a potent negative regulator of glucose uptake, aerobic glycolysis, and glycolytic gene expression; thus its repression by c-Myc provides an alternate route to c-Myc–driven glucose metabolism. c-Myc reduces TXNIP gene expression by binding to an E-box–containing region in the TXNIP promoter, possibly competing with the related transcription factor MondoA. TXNIP suppression increases glucose uptake and drives a dependence on glycolysis. Ectopic TXNIP expression decreases glucose uptake, reduces cell proliferation, and increases apoptosis. Supporting the biological significance of the reciprocal relationship between c-Myc and TXNIP, a Mychigh/TXNIPlow gene signature correlates with decreased overall survival and decreased metastasis-free survival in breast cancer. The correlation between the Mychigh/TXNIPlow gene signature and poor clinical outcome is evident only in TNBC, not in other breast cancer subclasses. Mutation of TP53, which is a defining molecular feature of TNBC, enhances the correlation between the Mychigh/TXNIPlow gene signature and death from breast cancer. Because Myc drives nutrient utilization and TXNIP restricts glucose availability, we propose that the Mychigh/TXNIPlow gene signature coordinates nutrient utilization with nutrient availability. Further, our data suggest that loss of the p53 tumor suppressor cooperates with Mychigh/TXNIPlow-driven metabolic dysregulation to drive the aggressive clinical behavior of TNBC. PMID:25870263

  16. Myc-Dependent Genome Instability and Lifespan in Drosophila

    PubMed Central

    Greer, Christina; Lee, Moonsook; Westerhof, Maaike; Milholland, Brandon; Spokony, Rebecca; Vijg, Jan; Secombe, Julie

    2013-01-01

    The Myc family of transcription factors are key regulators of cell growth and proliferation that are dysregulated in a large number of human cancers. When overexpressed, Myc family proteins also cause genomic instability, a hallmark of both transformed and aging cells. Using an in vivo lacZ mutation reporter, we show that overexpression of Myc in Drosophila increases the frequency of large genome rearrangements associated with erroneous repair of DNA double-strand breaks (DSBs). In addition, we find that overexpression of Myc shortens adult lifespan and, conversely, that Myc haploinsufficiency reduces mutation load and extends lifespan. Our data provide the first evidence that Myc may act as a pro-aging factor, possibly through its ability to greatly increase genome instability. PMID:24040302

  17. The jasmonate-responsive AaMYC2 transcription factor positively regulates artemisinin biosynthesis in Artemisia annua.

    PubMed

    Shen, Qian; Lu, Xu; Yan, Tingxiang; Fu, Xueqing; Lv, Zongyou; Zhang, Fangyuan; Pan, Qifang; Wang, Guofeng; Sun, Xiaofen; Tang, Kexuan

    2016-06-01

    The plant Artemisia annua is well known due to the production of artemisinin, a sesquiterpene lactone that is widely used in malaria treatment. Phytohormones play important roles in plant secondary metabolism, such as jasmonic acid (JA), which can induce artemisinin biosynthesis in A. annua. Nevertheless, the JA-inducing mechanism remains poorly understood. The expression of gene AaMYC2 was rapidly induced by JA and AaMYC2 binds the G-box-like motifs within the promoters of gene CYP71AV1 and DBR2, which are key structural genes in the artemisinin biosynthetic pathway. Overexpression of AaMYC2 in A. annua significantly activated the transcript levels of CYP71AV1 and DBR2, which resulted in an increased artemisinin content. By contrast, artemisinin content was reduced in the RNAi transgenic A. annua plants in which the expression of AaMYC2 was suppressed. Meanwhile, the RNAi transgenic A. annua plants showed lower sensitivity to methyl jasmonate treatment than the wild-type plants. These results demonstrate that AaMYC2 is a positive regulator of artemisinin biosynthesis and is of great value in genetic engineering of A. annua for increased artemisinin production. PMID:26864531

  18. Chromosomal translocations deregulating c-myc are associated with normal immune responses.

    PubMed

    Roschke, V; Kopantzev, E; Dertzbaugh, M; Rudikoff, S

    1997-06-26

    Plasmacytomas induced in BALB/c mice by pristane consistently evidence chromosomal translocations involving the c-myc gene and one of the Ig loci. This observation has lead to the suggestion that c-myc deregulation is a critical event in the generation of such tumors. However, it is not clear whether c-myc translocation is related to pristane treatment or occurs in normal lymphocyte populations nor whether such translocations occur normally, and at similar frequencies, in strains genetically resistant to plasmacytoma development, such as DBA/2. In order to address these questions, a Long Distance PCR assay with single copy sensitivity was employed to assess the frequency of c-myc/IgA translocations in normal and immunized mice of both plasmacytoma resistant and susceptible lineages in the absence of pristane treatment. Our data demonstrate that spontaneous translocations occur in normal DBA/2 and BALB/c mice with no significant differences in frequency. A 3-5-fold increase in translocation frequency was observed in mice immunized with cholera toxin, a strong stimulator of IgA responses. We conclude that c-myc deregulation by chromosomal translocation is associated with normal physiological processes of B-cell differentiation and, as such, can not be the determining factor leading to malignancy. PMID:9223664

  19. Combined genetic and transcriptomic analysis reveals three major signalling pathways activated by Myc-LCOs in Medicago truncatula.

    PubMed

    Camps, Céline; Jardinaud, Marie-Françoise; Rengel, David; Carrère, Sébastien; Hervé, Christine; Debellé, Frédéric; Gamas, Pascal; Bensmihen, Sandra; Gough, Clare

    2015-10-01

    Myc-LCOs are newly identified symbiotic signals produced by arbuscular mycorrhizal (AM) fungi. Like rhizobial Nod factors, they are lipo-chitooligosaccharides that activate the common symbiotic signalling pathway (CSSP) in plants. To increase our limited understanding of the roles of Myc-LCOs we aimed to analyse Myc-LCO-induced transcriptional changes and their genetic control. Whole genome RNA sequencing (RNA-seq) was performed on roots of Medicago truncatula wild-type plants, and dmi3 and nsp1 symbiotic mutants affected in nodulation and mycorrhizal signalling. Plants were treated separately with the two major types of Myc-LCOs, sulphated and nonsulphated. Generalized linear model analysis identified 2201 differentially expressed genes and classified them according to genotype and/or treatment effects. Three genetic pathways for Myc-LCO-regulation of transcriptomic reprogramming were highlighted: DMI3- and NSP1-dependent; DMI3-dependent and NSP1-independent; and DMI3- and NSP1-independent. Comprehensive analysis revealed overlaps with previous AM studies, and highlighted certain functions, especially signalling components and transcription factors. These data provide new insights into mycorrhizal signalling mechanisms, supporting a role for NSP1, and specialisation for NSP1-dependent and -independent pathways downstream of DMI3. Our data also indicate significant Myc-LCO-activated signalling upstream of DMI3 and/or parallel to the CSSP and some constitutive activity of the CSSP. PMID:25919491

  20. Identification of MYC-Dependent Transcriptional Programs in Oncogene-Addicted Liver Tumors.

    PubMed

    Kress, Theresia R; Pellanda, Paola; Pellegrinet, Luca; Bianchi, Valerio; Nicoli, Paola; Doni, Mirko; Recordati, Camilla; Bianchi, Salvatore; Rotta, Luca; Capra, Thelma; Ravà, Micol; Verrecchia, Alessandro; Radaelli, Enrico; Littlewood, Trevor D; Evan, Gerard I; Amati, Bruno

    2016-06-15

    Tumors driven by activation of the transcription factor MYC generally show oncogene addiction. However, the gene expression programs that depend upon sustained MYC activity remain unknown. In this study, we employed a mouse model of liver carcinoma driven by a reversible tet-MYC transgene, combined with chromatin immunoprecipitation and gene expression profiling to identify MYC-dependent regulatory events. As previously reported, MYC-expressing mice exhibited hepatoblastoma- and hepatocellular carcinoma-like tumors, which regressed when MYC expression was suppressed. We further show that cellular transformation, and thus initiation of liver tumorigenesis, were impaired in mice harboring a MYC mutant unable to associate with the corepressor protein MIZ1 (ZBTB17). Notably, switching off the oncogene in advanced carcinomas revealed that MYC was required for the continuous activation and repression of distinct sets of genes, constituting no more than half of all genes deregulated during tumor progression and an even smaller subset of all MYC-bound genes. Altogether, our data provide the first detailed analysis of a MYC-dependent transcriptional program in a fully developed carcinoma and offer a guide to identifying the critical effectors contributing to MYC-driven tumor maintenance. Cancer Res; 76(12); 3463-72. ©2016 AACR. PMID:27197165

  1. Tumor cell-specific inhibition of MYC function using small molecule inhibitors of the HUWE1 ubiquitin ligase.

    PubMed

    Peter, Stefanie; Bultinck, Jennyfer; Myant, Kevin; Jaenicke, Laura A; Walz, Susanne; Müller, Judith; Gmachl, Michael; Treu, Matthias; Boehmelt, Guido; Ade, Carsten P; Schmitz, Werner; Wiegering, Armin; Otto, Christoph; Popov, Nikita; Sansom, Owen; Kraut, Norbert; Eilers, Martin

    2014-12-01

    Deregulated expression of MYC is a driver of colorectal carcinogenesis, necessitating novel strategies to inhibit MYC function. The ubiquitin ligase HUWE1 (HECTH9, ARF-BP1, MULE) associates with both MYC and the MYC-associated protein MIZ1. We show here that HUWE1 is required for growth of colorectal cancer cells in culture and in orthotopic xenograft models. Using high-throughput screening, we identify small molecule inhibitors of HUWE1, which inhibit MYC-dependent transactivation in colorectal cancer cells, but not in stem and normal colon epithelial cells. Inhibition of HUWE1 stabilizes MIZ1. MIZ1 globally accumulates on MYC target genes and contributes to repression of MYC-activated target genes upon HUWE1 inhibition. Our data show that transcriptional activation by MYC in colon cancer cells requires the continuous degradation of MIZ1 and identify a novel principle that allows for inhibition of MYC function in tumor cells. PMID:25253726

  2. Evolution of B-cell malignancy; Pre-B-cell leukemia resulting from MYC activation in a B-cell neoplasm with a rearranged BCL2 gene

    SciTech Connect

    Gauwerky, C.E.; Haluska, F.G.; Tsujimoto, Y.; Nowell, P.C.; Croce, C.M. )

    1988-11-01

    The authors have analyzed the molecular genetics of the breakpoints involved in the t(8;14) and t(14;18) translocations of an acute pre-B-cell leukemia from a patient with a history of follicular lymphoma. In this patient's leukemic cells, the breakpoint of the t(14;18) translocation occurred in the major breakpoint-cluster region of the BCL2 gene and became linked to the J{sub H}4 joining-region gene segment of the immunoglobulin heavy-chain locus on the 14q+ chromosome as previously observed in follicular lymphoma. An N region and heptamer and nonamer signal sequences indicated that this translocation occurred as a mistake in V{sub H}-D{sub H}-J{sub H} joining (where V{sub H} and D{sub H} are the variable and diversity segments). In the t(8;14) translocation, the breakpoint was located immediately 5' of the first exon of the MYC protooncogene, which was juxtaposed with the C{gamma}2 constant gene segment of the second 14q+ chromosome. The finding of repeated sequences typical of switch regions suggested that this translocation occurred during heavy-chain isotype switching, resulting in progression to pre-B-cell leukemia with both the 5(8;14) and the t(14;18) translocations. The terminal deoxynucleotidyltransferase-positive phenotype of the patient's leukemic cells further suggests that the pre-B-cell leukemia was derived from a pre-B cell carrying a t(14;18) translocation in the original follicular lymphoma. The polymerase chain reaction method was then used to identify cancer cells in the bone marrow of the patient.

  3. Myc Prevents Apoptosis and Enhances Endoreduplication Induced by Paclitaxel

    PubMed Central

    Gatti, Giuliana; Maresca, Giovanna; Natoli, Manuela; Florenzano, Fulvio; Nicolin, Angelo; Felsani, Armando; D'Agnano, Igea

    2009-01-01

    Background The role of the MYC oncogene in the apoptotic pathways is not fully understood. MYC has been reported to protect cells from apoptosis activation but also to sensitize cells to apoptotic stimuli. We have previously demonstrated that the down-regulation of Myc protein activates apoptosis in melanoma cells and increases the susceptibility of cells to various antitumoral treatments. Beyond the well-known role in the G1→S transition, MYC is also involved in the G2-M cell cycle phases regulation. Methodology/Principal Findings In this study we have investigated how MYC could influence cell survival signalling during G2 and M phases. We used the microtubules damaging agent paclitaxel (PTX), to arrest the cells in the M phase, in a p53 mutated melanoma cell line with modulated Myc level and activity. An overexpression of Myc protein is able to increase endoreduplication favoring the survival of cells exposed to antimitotic poisoning. The PTX-induced endoreduplication is associated in Myc overexpressing cells with a reduced expression of MAD2, essential component of the molecular core of the spindle assembly checkpoint (SAC), indicating an impairment of this checkpoint. In addition, for the first time we have localized Myc protein at the spindle poles (centrosomes) during pro-metaphase in different cell lines. Conclusions The presence of Myc at the poles during the prometaphase could be necessary for the Myc-mediated attenuation of the SAC and the subsequent induction of endoreduplication. In addition, our data strongly suggest that the use of taxane in antitumor therapeutic strategies should be rationally based on the molecular profile of the individual tumor by specifically analyzing Myc expression levels. PMID:19421315

  4. Aminoglycoside uptake increased by tet gene expression.

    PubMed Central

    Merlin, T L; Davis, G E; Anderson, W L; Moyzis, R K; Griffith, J K

    1989-01-01

    The expression of extrachromosomal tet genes not only confers tetracycline resistance but also increases the susceptibilities of gram-negative bacteria to commonly used aminoglycoside antibiotics. We investigated the possibility that tet expression increases aminoglycoside susceptibility by increasing bacterial uptake of aminoglycoside. Studies of [3H]gentamicin uptake in paired sets of Escherichia coli HB101 and Salmonella typhimurium LT2 expressing and not expressing tet showed that tet expression accelerates energy-dependent [3H]gentamicin uptake. Increased [3H]gentamicin uptake was accompanied by decreased bacterial protein synthesis and bacterial growth. Increased aminoglycoside uptake occurred whether tet expression was constitutive or induced, whether the tet gene was class B or C, and whether the tet gene was plasmid borne or integrated into the bacterial chromosome. tet expression produced no measurable change in membrane potential, suggesting that tet expression increases aminoglycoside uptake either by increasing the availability of specific carriers or by lowering the minimum membrane potential that is necessary for uptake. PMID:2684011

  5. Novel thiosemicarbazone iron chelators induce up-regulation and phosphorylation of the metastasis suppressor N-myc down-stream regulated gene 1: a new strategy for the treatment of pancreatic cancer.

    PubMed

    Kovacevic, Zaklina; Chikhani, Sherin; Lovejoy, David B; Richardson, Des R

    2011-10-01

    Pancreatic cancer is an aggressive neoplasm, with a mortality rate close to 100%. The most successful agent for pancreatic cancer treatment is gemcitabine, although the overall effect in terms of patient survival remains very poor. This study was initiated to evaluate a novel class of anticancer agents against pancreatic cancer. This group of compounds belongs to the dipyridyl thiosemicarbazone class that have been shown to have potent and selective activity against a range of different neoplasms in vitro and in vivo. We demonstrate for the first time in pancreatic cancer that these agents increase the expression of the growth and metastasis suppressor N-myc downstream-regulated gene 1 and its phosphorylation at Ser330 and Thr346 that is important for its activity against this tumor. In addition, these agents increased expression of the cyclin-dependent kinase inhibitor p21(CIP1/WAF1), whereas decreasing cyclin D1 in pancreatic cancer cells. Together, these molecular alterations account, in part, for the pronounced antitumor activity observed. Indeed, these agents had significantly higher antiproliferative activity in vitro than the established treatments for pancreatic cancer, namely gemcitabine and 5-fluorouracil. Studies in vivo demonstrated that a novel thiosemicarbazone, namely di-2-pyridylketone 4-cyclohexyl-4-methyl-3-thiosemicarbazone hydrochloride, completely inhibited the growth of pancreatic cancer xenografts with no evidence of marked alterations in normal tissue histology. Together, our studies have identified molecular effectors of a novel and potent antitumor agent that could be useful for pancreatic cancer treatment. PMID:21719465

  6. MYC-IG rearrangements are negative predictors of survival in DLBCL patients treated with immunochemotherapy: a GELA/LYSA study.

    PubMed

    Copie-Bergman, Christiane; Cuillière-Dartigues, Peggy; Baia, Maryse; Briere, Josette; Delarue, Richard; Canioni, Danielle; Salles, Gilles; Parrens, Marie; Belhadj, Karim; Fabiani, Bettina; Recher, Christian; Petrella, Tony; Ketterer, Nicolas; Peyrade, Frederic; Haioun, Corinne; Nagel, Inga; Siebert, Reiner; Jardin, Fabrice; Leroy, Karen; Jais, Jean-Philippe; Tilly, Herve; Molina, Thierry Jo; Gaulard, Philippe

    2015-11-26

    Diffuse large B-cell lymphoma (DLBCL) with MYC rearrangement (MYC-R) carries an unfavorable outcome. We explored the prognostic value of the MYC translocation partner gene in a series of MYC-R de novo DLBCL patients enrolled in first-line prospective clinical trials (Groupe d'Etudes des Lymphomes de l'Adulte/Lymphoma Study Association) and treated with rituximab-anthracycline-based chemotherapy. A total of 774 DLBCL cases characterized for cell of origin by the Hans classifier were analyzed using fluorescence in situ hybridization with BCL2, BCL6, MYC, immunoglobulin (IG)K, and IGL break-apart and IGH/MYC, IGK/MYC, and IGL/MYC fusion probes. MYC-R was observed in 51/574 (8.9%) evaluable DLBCL cases. MYC-R cases were predominantly of the germinal center B-cell-like subtype 37/51 (74%) with no distinctive morphologic and phenotypic features. Nineteen cases were MYC single-hit and 32 cases were MYC double-hit (MYC plus BCL2 and/or BCL6) DLBCL. MYC translocation partner was an IG gene in 24 cases (MYC-IG) and a non-IG gene (MYC-non-IG) in 26 of 50 evaluable cases. Noteworthy, MYC-IG patients had shorter overall survival (OS) (P = .0002) compared with MYC-negative patients, whereas no survival difference was observed between MYC-non-IG and MYC-negative patients. In multivariate analyses, MYC-IG predicted poor progression-free survival (P = .0051) and OS (P = .0006) independently from the International Prognostic Index and the Hans classifier. In conclusion, we show in this prospective randomized trial that the adverse prognostic impact of MYC-R is correlated to the MYC-IG translocation partner gene in DLBCL patients treated with immunochemotherapy. These results may have an important impact on the clinical management of DLBCL patients with MYC-R who should be routinely characterized according to MYC partner gene. These trials are individually registered at www.clinicaltrials.gov as #NCT00144807, #NCT01087424, #NCT00169143, #NCT00144755, #NCT00140660, #NCT00140595, and

  7. p19ARF is a critical mediator of both cellular senescence and an innate immune response associated with MYC inactivation in mouse model of acute leukemia

    PubMed Central

    Yetil, Alper; Anchang, Benedict; Gouw, Arvin M.; Adam, Stacey J.; Zabuawala, Tahera; Parameswaran, Ramya; van Riggelen, Jan; Plevritis, Sylvia; Felsher, Dean W.

    2015-01-01

    MYC-induced T-ALL exhibit oncogene addiction. Addiction to MYC is a consequence of both cell-autonomous mechanisms, such as proliferative arrest, cellular senescence, and apoptosis, as well as non-cell autonomous mechanisms, such as shutdown of angiogenesis, and recruitment of immune effectors. Here, we show, using transgenic mouse models of MYC-induced T-ALL, that the loss of either p19ARF or p53 abrogates the ability of MYC inactivation to induce sustained tumor regression. Loss of p53 or p19ARF, influenced the ability of MYC inactivation to elicit the shutdown of angiogenesis; however the loss of p19ARF, but not p53, impeded cellular senescence, as measured by SA-beta-galactosidase staining, increased expression of p16INK4A, and specific histone modifications. Moreover, comparative gene expression analysis suggested that a multitude of genes involved in the innate immune response were expressed in p19ARF wild-type, but not null, tumors upon MYC inactivation. Indeed, the loss of p19ARF, but not p53, impeded the in situ recruitment of macrophages to the tumor microenvironment. Finally, p19ARF null-associated gene signature prognosticated relapse-free survival in human patients with ALL. Therefore, p19ARF appears to be important to regulating cellular senescence and innate immune response that may contribute to the therapeutic response of ALL. PMID:25784651

  8. Analysis of secretome changes uncovers an autocrine/paracrine component in the modulation of cell proliferation and motility by c-Myc.

    PubMed

    Pocsfalvi, Gabriella; Votta, Giuseppina; De Vincenzo, Anna; Fiume, Immacolata; Raj, Delfin Albert Amal; Marra, Giancarlo; Stoppelli, Maria Patrizia; Iaccarino, Ingram

    2011-12-01

    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. PMID:22011035

  9. N-myc downstream regulated gene 2 overexpression reduces matrix metalloproteinase-2 and -9 activities and cell invasion of A549 lung cancer cell line in vitro

    PubMed Central

    Faraji, Seyed Nooredin; Mojtahedi, Zahra; Ghalamfarsa, Ghasem; Takhshid, Mohammad Ali

    2015-01-01

    Objective(s): N-myc downstream regulated gene 2 (NDRG2) is a candidate gene for tumor suppression. The expression of NDRG2 is down-regulated in several tumors including lung cancer. The aim of this study was to explore the effect of NDRG2 overexpression on invasion, migration, and enzymatic activity of matrix metalloproteinase-2 (MMP-2) and -9 (MMP-9) in human lung adenocarcinoma A549 cells. Materials and Methods: A recombinant plasmid encoding green fluorescent protein (GFP)-tagged NDRG2 (pCMV6-AC-NDRG2-GFP) was used to overexpress GFP-tagged NDRG2 in A549 cells. The cells in the experimental group and those in the control group were transfected with pCMV6-AC-NDRG2-GFP and a control plasmid without NDRG2 (pCMV6-AC-GFP), respectively. Fluorescent microscopy and flowcytometry analysis of GFP expression were used to evaluate the cellular expression of GFP-tagged NDRG2 and the efficiency of transfection. The effects of NDRG2 expression on cell invasion and migration were evaluated using transwell filter migration assay. The gelatinase activity of secreted MMP-2 and MMP-9 was measured by gelatin zymography. Results: Our results demonstrated the expression of GFP-tagged NDRG2 in the cytoplasm and nucleus of A549 cells. The findings of transwell assay showed that NDRG2 overexpression reduced migration and invasion of A549 cells compared to control cells. Gelatin zymography analyses revealed that NDRG2 overexpression decreased the gelatinase activity of secreted MMP-2 and MMP-9. Conclusion: These findings suggest that NDRG2 may be a new anti-invasion factor in lung cancer that inhibits MMPs activities. PMID:26557966

  10. Masking Epistasis Between MYC and TGF-β Pathways in Antiangiogenesis-Mediated Colon Cancer Suppression

    PubMed Central

    2014-01-01

    Background The c-Myc oncoprotein is activated in the majority of colorectal cancers (CRCs), whereas the TGF-β pathway is frequently affected by loss-of-function mutations, for example in SMAD2/3/4 genes. The canonical model places Myc downstream of inhibitory TGF-β signaling. However, we previously demonstrated that Myc also inhibits TGF-β signaling through the miR-17~92 microRNA cluster, raising the question about functional relationships between these two pathways. Methods We engineered a series of genetically complex murine and human CRC cell lines in which Myc and TGF-β activities could be manipulated simultaneously. This was achieved through retroviral expression of the Myc–estrogen receptor fusion protein and through Smad4 short hairpin RNA knockdown. Cell lines thus modified were injected subcutaneously in immunocompromised mice, and the resultant tumors (n = 5–10 per treatment group) were analyzed for overall growth and neovascularization. Additionally, the distribution of MYC and TGF-β pathway mutations was analyzed in previously profiled human CRC samples. Results In kras-mutated/trp53-deleted murine colonocytes, either Myc activation or TGF-β inactivation increased tumor sizes and microvascular densities approximately 1.5- to 2.5-fold, chiefly through downregulation of thrombospondin-1 and related type I repeat–containing proteins. Combining Myc activation with TGF-β inactivation did not further accelerate tumorigenesis. This redundancy and the negative effect of TGF-β signaling on angiogenesis were also demonstrated using xenografts of human CRC cell lines. Furthermore, the analysis of the Cancer Genome Atlas data revealed that in CRC without microsatellite instability, overexpression of Myc and inactivation of Smads (including acquired mutations in SMAD2) are mutually exclusive, with odds ratio less than 0.1. Conclusions In human CRC, gain-of-function alterations in Myc and loss-of-function alterations in TGF-β exhibit a masking

  11. Strategically targeting MYC in cancer

    PubMed Central

    Posternak, Valeriya; Cole, Michael D.

    2016-01-01

    MYC is a major driver of cancer cell growth and mediates a transcriptional program spanning cell growth, the cell cycle, metabolism, and cell survival. Many efforts have been made to deliberately target MYC for cancer therapy. A variety of compounds have been generated to inhibit MYC function or stability, either directly or indirectly. The most direct inhibitors target the interaction between MYC and MAX, which is required for DNA binding. Unfortunately, these compounds do not have the desired pharmacokinetics and pharmacodynamics for in vivo application. Recent studies report the indirect inhibition of MYC through the development of two compounds, JQ1 and THZ1, which target factors involved in unique stages of transcription. These compounds appear to have significant therapeutic value for cancers with high levels of MYC, although some effects are MYC-independent. These approaches serve as a foundation for developing novel compounds to pharmacologically target MYC-driven cancers. PMID:27081479

  12. MYC Is a Major Determinant of Mitotic Cell Fate

    PubMed Central

    Topham, Caroline; Tighe, Anthony; Ly, Peter; Bennett, Ailsa; Sloss, Olivia; Nelson, Louisa; Ridgway, Rachel A.; Huels, David; Littler, Samantha; Schandl, Claudia; Sun, Ying; Bechi, Beatrice; Procter, David J.; Sansom, Owen J.; Cleveland, Don W.; Taylor, Stephen S.

    2015-01-01

    Summary Taxol and other antimitotic agents are frontline chemotherapy agents but the mechanisms responsible for patient benefit remain unclear. Following a genome-wide siRNA screen, we identified the oncogenic transcription factor Myc as a taxol sensitizer. Using time-lapse imaging to correlate mitotic behavior with cell fate, we show that Myc sensitizes cells to mitotic blockers and agents that accelerate mitotic progression. Myc achieves this by upregulating a cluster of redundant pro-apoptotic BH3-only proteins and suppressing pro-survival Bcl-xL. Gene expression analysis of breast cancers indicates that taxane responses correlate positively with Myc and negatively with Bcl-xL. Accordingly, pharmacological inhibition of Bcl-xL restores apoptosis in Myc-deficient cells. These results open up opportunities for biomarkers and combination therapies that could enhance traditional and second-generation antimitotic agents. PMID:26175417

  13. MYC Is a Major Determinant of Mitotic Cell Fate.

    PubMed

    Topham, Caroline; Tighe, Anthony; Ly, Peter; Bennett, Ailsa; Sloss, Olivia; Nelson, Louisa; Ridgway, Rachel A; Huels, David; Littler, Samantha; Schandl, Claudia; Sun, Ying; Bechi, Beatrice; Procter, David J; Sansom, Owen J; Cleveland, Don W; Taylor, Stephen S

    2015-07-13

    Taxol and other antimitotic agents are frontline chemotherapy agents but the mechanisms responsible for patient benefit remain unclear. Following a genome-wide siRNA screen, we identified the oncogenic transcription factor Myc as a taxol sensitizer. Using time-lapse imaging to correlate mitotic behavior with cell fate, we show that Myc sensitizes cells to mitotic blockers and agents that accelerate mitotic progression. Myc achieves this by upregulating a cluster of redundant pro-apoptotic BH3-only proteins and suppressing pro-survival Bcl-xL. Gene expression analysis of breast cancers indicates that taxane responses correlate positively with Myc and negatively with Bcl-xL. Accordingly, pharmacological inhibition of Bcl-xL restores apoptosis in Myc-deficient cells. These results open up opportunities for biomarkers and combination therapies that could enhance traditional and second-generation antimitotic agents. PMID:26175417

  14. The adenoviral E1A N-terminal domain represses MYC transcription in human cancer cells by targeting both p300 and TRRAP and inhibiting MYC promoter acetylation of H3K18 and H4K16

    PubMed Central

    Zhao, Ling-Jun; Loewenstein, Paul M.; Green, Maurice

    2016-01-01

    Human cancers frequently arise from increased expression of proto-oncogenes, such as MYC and HER2. Understanding the cellular pathways regulating the transcription and expression of proto-oncogenes is important for targeted therapies for cancer treatment. Adenoviral (Ad) E1A 243R (243 aa residues) is a viral oncoprotein that interacts with key regulators of gene transcription and cell proliferation. We have shown previously that the 80 amino acid N-terminal transcriptional repression domain of E1A 243R (E1A 1-80) can target the histone acetyltransferase (HAT) p300 and repress HER2 in the HER2-overexpressing human breast cancer cell line SKBR3. Expression of E1A 1-80 induces death of SKBR3 and other cancer cell lines. In this study, we performed total cell RNA sequence analysis and identified MYC as the regulatory gene for cellular proliferation most strongly repressed by E1A 1-80. By RT-quantitative PCR analysis we show that repression of MYC in SKBR3 cells occurs early after expression of E1A 1-80, suggesting that MYC may be an early responder of E1A 1-80-mediated transcriptional repression. Of interest, while E1A 1-80 repression of MYC occurs in all eight human cancer cell lines examined, repression of HER2 is cell-type dependent. We demonstrate by ChIP analysis that MYC transcriptional repression by E1A 1-80 is associated with inhibition of acetylation of H3K18 and H4K16 on the MYC promoter, as well as inhibition of RNA Pol II binding to the MYC promoter. Deletion mutant analysis of E1A 1-80 suggests that both p300/CBP and TRRAP are involved in E1A 1-80 repression of MYC transcription. Further, E1A 1-80 interaction with p300/CBP and TRRAP is correlated with inhibition of H3K18 and H4K16 acetylation on the MYC promoter, respectively. Our results indicate that E1A 1-80 may target two important pathways for histone modification to repress transcription in human cancer cells.

  15. Perfusion of veins at arterial pressure increases the expression of KLF5 and cell cycle genes in smooth muscle cells

    SciTech Connect

    Amirak, Emre; Zakkar, Mustafa; Evans, Paul C.; Kemp, Paul R.

    2010-01-01

    Vascular smooth muscle cell (VSMC) proliferation remains a major cause of veno-arterial graft failure. We hypothesised that exposure of venous SMCs to arterial pressure would increase KLF5 expression and that of cell cycle genes. Porcine jugular veins were perfused at arterial or venous pressure in the absence of growth factors. The KLF5, c-myc, cyclin-D and cyclin-E expression were elevated within 24 h of perfusion at arterial pressure but not at venous pressure. Arterial pressure also reduced the decline in SM-myosin heavy chain expression. These data suggest a role for KLF5 in initiating venous SMCs proliferation in response to arterial pressure.

  16. Small-Molecule Inhibitors of the Myc Oncoprotein

    PubMed Central

    Fletcher, Steven; Prochownik, Edward V.

    2014-01-01

    The c-Myc (Myc) oncoprotein is among the most attractive of cancer targets given that is deregulated in the majority of tumors and that its inhibition profoundly affects their growth and/or survival. However, its role as a seldom-mutated transcription factor, its lack of enzymatic activity for which suitable pharmaceutical inhibitors could be crafted and its expression by normal cells have largely been responsible for its being viewed as “undruggable”. Work over the past several years, however, has begun to reverse this idea by allowing us to view Myc within the larger context of global gene regulatory control. Thus, Myc and its obligate heterodimeric partner, Max, are integral to the coordinated recruitment and post-translational modification of components of the core transcriptional machinery. Moreover, Myc over-expression re-programs numerous critical cellular functions and alters the cell’s susceptibility to their inhibition. This new knowledge has therefore served as a framework upon which to develop new pharmaceutical approaches. These include the continuing development of small molecules which act directly to inhibit the critical Myc-Max interaction, those which act indirectly to prevent Myc-directed post-translational modifications necessary to initiate productive transcription and those which inhibit vital pathways upon which the Myc-transformed cell is particularly reliant. PMID:24657798

  17. A Gly98Val mutation in the N-Myc downstream regulated gene 1 (NDRG1) in Alaskan Malamutes with polyneuropathy.

    PubMed

    Bruun, Camilla S; Jäderlund, Karin H; Berendt, Mette; Jensen, Kristine B; Spodsberg, Eva H; Gredal, Hanne; Shelton, G Diane; Mickelson, James R; Minor, Katie M; Lohi, Hannes; Bjerkås, Inge; Stigen, Oyvind; Espenes, Arild; Rohdin, Cecilia; Edlund, Rebecca; Ohlsson, Jennie; Cizinauskas, Sigitas; Leifsson, Páll S; Drögemüller, Cord; Moe, Lars; Cirera, Susanna; Fredholm, Merete

    2013-01-01

    The first cases of early-onset progressive polyneuropathy appeared in the Alaskan Malamute population in Norway in the late 1970s. Affected dogs were of both sexes and were ambulatory paraparetic, progressing to non-ambulatory tetraparesis. On neurologic examination, affected dogs displayed predominantly laryngeal paresis, decreased postural reactions, decreased spinal reflexes and muscle atrophy. The disease was considered eradicated through breeding programmes but recently new cases have occurred in the Nordic countries and the USA. The N-myc downstream-regulated gene (NDRG1) is implicated in neuropathies with comparable symptoms or clinical signs both in humans and in Greyhound dogs. This gene was therefore considered a candidate gene for the polyneuropathy in Alaskan Malamutes. The coding sequence of the NDRG1 gene derived from one healthy and one affected Alaskan Malamute revealed a non-synonymous G>T mutation in exon 4 in the affected dog that causes a Gly98Val amino acid substitution. This substitution was categorized to be "probably damaging" to the protein function by PolyPhen2 (score: 1.000). Subsequently, 102 Alaskan Malamutes from the Nordic countries and the USA known to be either affected (n = 22), obligate carriers (n = 7) or healthy (n = 73) were genotyped for the SNP using TaqMan. All affected dogs had the T/T genotype, the obligate carriers had the G/T genotype and the healthy dogs had the G/G genotype except for 13 who had the G/T genotype. A protein alignment showed that residue 98 is conserved in mammals and also that the entire NDRG1 protein is highly conserved (94.7%) in mammals. We conclude that the G>T substitution is most likely the mutation that causes polyneuropathy in Alaskan Malamutes. Our characterization of a novel candidate causative mutation for polyneuropathy offers a new canine model that can provide further insight into pathobiology and therapy of human polyneuropathy. Furthermore, selection against this mutation can

  18. CTCF, a conserved nuclear factor required for optimal transcriptional activity of the chicken c-myc gene, is an 11-Zn-finger protein differentially expressed in multiple forms.

    PubMed Central

    Klenova, E M; Nicolas, R H; Paterson, H F; Carne, A F; Heath, C M; Goodwin, G H; Neiman, P E; Lobanenkov, V V

    1993-01-01

    A novel sequence-specific DNA-binding protein, CTCF, which interacts with the chicken c-myc gene promoter, has been identified and partially characterized (V. V. Lobanenkov, R. H. Nicolas, V. V. Adler, H. Paterson, E. M. Klenova, A. V. Polotskaja, and G. H. Goodwin, Oncogene 5:1743-1753, 1990). In order to test directly whether binding of CTCF to one specific DNA region of the c-myc promoter is important for chicken c-myc transcription, we have determined which nucleotides within this GC-rich region are responsible for recognition of overlapping sites by CTCF and Sp1-like proteins. Using missing-contact analysis of all four nucleotides in both DNA strands and homogeneous CTCF protein purified by sequence-specific chromatography, we have identified three sets of nucleotides which contact either CTCF or two Sp1-like proteins binding within the same DNA region. Specific mutations of 3 of 15 purines required for CTCF binding were designed to eliminate binding of CTCF without altering the binding of other proteins. Electrophoretic mobility shift assay of nuclear extracts showed that the mutant DNA sequence did not bind CTCF but did bind two Sp1-like proteins. When introduced into a 3.3-kbp-long 5'-flanking noncoding c-myc sequence fused to a reporter CAT gene, the same mutation of the CTCF binding site resulted in 10- and 3-fold reductions, respectively, of transcription in two different (erythroid and myeloid) stably transfected chicken cell lines. Isolation and analysis of the CTCF cDNA encoding an 82-kDa form of CTCF protein shows that DNA-binding domain of CTCF is composed of 11 Zn fingers: 10 are of C2H2 class, and 1 is of C2HC class. CTCF was found to be abundant and conserved in cells of vertebrate species. We detected six major nuclear forms of CTCF protein differentially expressed in different chicken cell lines and tissues. We conclude that isoforms of 11-Zn-finger factor CTCF which are present in chicken hematopoietic HD3 and BM2 cells can act as a positive

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

    PubMed Central

    Tsai, Jia-Shiuan; Chao, Cheng-Han; Lin, Lih-Yuan

    2016-01-01

    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. PMID:26751215

  20. MYC Deregulation in Gastric Cancer and Its Clinicopathological Implications

    PubMed Central

    de Souza, Carolina Rosal Teixeira; Leal, Mariana Ferreira; Calcagno, Danielle Queiroz; Costa Sozinho, Eliana Kelly; Borges, Bárbara do Nascimento; Montenegro, Raquel Carvalho; dos Santos, Ândrea Kely Campos Ribeiro; dos Santos, Sidney Emanuel Batista; Ribeiro, Helem Ferreira; Assumpção, Paulo Pimentel; de Arruda Cardoso Smith, Marília; Burbano, Rommel Rodríguez

    2013-01-01

    Our study investigated the relationship between MYC alterations and clinicopathological features in gastric cancers. We evaluated the effect of MYC mRNA expression and its protein immunoreactivity, as well as copy number variation, promoter DNA methylation, and point mutations, in 125 gastric adenocarcinoma and 67 paried non-neoplastic tissues. We observed that 77% of the tumors presented MYC immunoreactivity which was significantly associated with increased mRNA expression (p<0.05). These observations were associated with deeper tumor extension and the presence of metastasis (p<0.05). MYC protein expression was also more frequently observed in intestinal-type than in diffuse-type tumors (p<0.001). Additionally, MYC mRNA and protein expression were significantly associated with its copy number (p<0.05). The gain of MYC copies was associated with late-onset, intestinal-type, advanced tumor stage, and the presence of distant metastasis (p<0.05). A hypomethylated MYC promoter was detected in 86.4% of tumor samples. MYC hypomethylation was associated with diffuse-type, advanced tumor stage, deeper tumor extension, and the presence of lymph node metastasis (p<0.05). Moreover, eighteen tumor samples presented at least one known mutation. The presence of MYC mutations was associated with diffuse-type tumor (p<0.001). Our results showed that MYC deregulation was mainly associated with poor prognostic features and also reinforced the presence of different pathways involved in intestinal-type and diffuse-type gastric carcinogenesis. Thus, our findings suggest that MYC may be a useful marker for clinical stratification and prognosis. PMID:23717612

  1. Management of Patients with MYC-Altered Lymphomas.

    PubMed

    Landsburg, Daniel J

    2016-06-01

    Patients diagnosed with non-Burkitt high-grade B cell non-Hodgkin lymphomas demonstrating rearrangement in MYC, an oncogene promoting cellular proliferation, frequently do not achieve long-term disease-free survival due to a suboptimal response to standard front-line and salvage therapies. Double-hit lymphomas, harboring rearrangements in MYC as well as BCL2 and/or BCL6, appear to carry a particularly poor prognosis, although patients with this disease appear to achieve better survival outcomes when treated with intensified chemotherapy. Increased expression of MYC protein by immunohistochemistry as well as increased copy number or amplification of MYC may also be adverse pathologic features of non-Burkitt high-grade B cell non-Hodgkin lymphomas, although the benefit of treating these patients with intensified as opposed to standard dose chemotherapy remains unclear. Recognition and proper management of patients with MYC-altered lymphomas is crucial to improving patient outcomes. PMID:26983958

  2. Role of MYC in Medulloblastoma

    PubMed Central

    Roussel, Martine F.; Robinson, Giles W.

    2013-01-01

    Since its discovery as an oncogene carried by the avian acute leukemia virus MC29 in myelocytomatosis (Roussel et al. 1979) and its cloning (Vennstrom et al. 1982), c-MYC (MYC), as well as its paralogs MYCN and MYCL1, has been shown to play essential roles in cycling progenitor cells born from proliferating zones during embryonic development, and in all proliferating cells after birth. MYC deletion induces cell-cycle exit or cell death, depending on the cell type and milieu, whereas MYC and MYCN amplification or overexpression promotes cell proliferation and occurs in many cancers. Here, we review the relationship of MYC family proteins to the four molecularly distinct medulloblastoma subgroups, discuss the possible roles MYC plays in each of these subgroups and in the developing cells of the posterior fossa, and speculate on possible therapeutic strategies targeting MYC. PMID:24186490

  3. SUMO-activating SAE1 transcription is positively regulated by Myc

    PubMed Central

    Amente, Stefano; Lavadera, Miriam Lubrano; Palo, Giacomo Di; Majello, Barbara

    2012-01-01

    Myc protein plays a fundamental role in regulation of cell cycle, proliferation, differentiation and apoptosis by modulating the expression of a large number of targets. Here we report the transactivation ability of the human Myc protein to activate the SUMO-activating enzyme SAE1 transcription. We found that Myc activates SAE1 transcription via direct binding to canonical E-Boxes sequences located close to the SAE1 transcription start site. A recent report has highlighted the crucial role of the SAE gene expression in Myc mediated oncogenesis. Our study adds new insight in this context since we show here that Myc directly activates SAE1 transcription, suggesting that Myc oncogenic activity which depends on SAE1 is ensured by Myc itself through direct binding and transcriptional activation of SAE1 expression. PMID:22679563

  4. Identification of N-myc regulatory regions involved in embryonic expression.

    PubMed

    Charron, Jean; Gagnon, Jean-François; Cadrin-Girard, Jean François

    2002-01-01

    Our knowledge on the regulation of the N-myc proto-oncogene expression comes mostly from in vitro studies. Very few in vivo analyses have been performed to identify the regulatory elements involved in N-myc developmental expression. In the present study, we defined DNA regions required for the regulated expression of N-myc during early embryogenesis. We showed that the expression of N-myc driven by the human N-myc sequences previously described to control N-myc expression in appropriate cell types in vitro cannot rescue the mouse N-myc mutant phenotype, suggesting that regulatory elements necessary for N-myc embryonic expression were missing. To identify the regulatory DNA regions involved in N-myc expression, transgenic mouse lines carrying N-myc/lacZ reporter constructs were generated. Beta-galactosidase staining analysis at different stages of gestation revealed that >16 kb of mouse N-myc genomic sequences are required to recapitulate the entire spatiotemporal expression pattern of the endogenous N-myc gene between embryonic d 8.5 and 11.5. This observation supported the notion that the sequences previously identified by in vitro assays were not sufficient to reproduce the N-myc embryonic expression pattern. However, regulatory elements that can direct specific expression in the visceral arches, the limb buds, the CNS, and the dorsal root ganglia are included into the mouse N-myc genomic sequences tested. Altogether, these findings indicated that the regulation of the spatiotemporal expression pattern of N-myc during development necessitates multiple regulatory DNA elements. PMID:11756639

  5. Identification of novel targets of MYC whose transcription requires the essential MbII domain.

    PubMed

    Zhang, Xiao-yong; DeSalle, Lauren M; McMahon, Steven B

    2006-02-01

    The MYC oncoprotein is among the most potent regulators of cell cycle progression and malignant transformation in human cells. Current models suggest that much of MYC's role in these processes is related to its ability to regulate the transcription of downstream target genes that encode the ultimate effector proteins. In addition to its carboxy-terminal DNA binding and dimerization domains, an enigmatic motif in the amino terminus termed MbII is required for all of MYC's biological activities. In spite of historical observations demonstrating the absolute requirement for MbII in these biological functions, clues implicating this domain in target gene transcription have only recently appeared. Based on this emerging link between MbII and transcriptional activation, we hypothesized that the identification of individual MYC targets whose transactivation requires MbII would help define the essential downstream effectors of MYC in transformation and cell cycle progression. In hopes of directly identifying new MbII-dependent MYC target genes, an expression profiling screen was conducted. This screen resulted in our identification of ten novel downstream targets of MYC. As a proof of principle, we recently demonstrated using RNAi-mediated depletion that one of these targets, the metastasis regulator MTA1, is absolutely required for MYC mediated transformation. Here we report the identity of these previously uncharacterized MYC targets and discuss their potential roles in MYC function. In addition, we attempt to reconcile the historical and contemporary evidence linking MbII to transcriptional activation. PMID:16434883

  6. Promoter-binding and repression of PDGFRB by c-Myc are separable activities

    PubMed Central

    Mao, Daniel Y. L.; Barsyte-Lovejoy, Dalia; Ho, Cynthia S. W.; Watson, John D.; Stojanova, Angelina; Penn, Linda Z.

    2004-01-01

    The c-Myc transcription factor represses the mRNA expression of the platelet-derived growth factor receptor beta gene (PDGFRB). Using chromatin immunoprecipitation, we show that c-Myc binds to the proximal promoter of the PDGFRB gene in proliferating rat fibroblasts. Interestingly, mutant c-Myc proteins that are unable to repress PDGFRB gene expression, c-MycdBR and c-Mycd106-143, are still able to bind to the promoter in vivo. Hence, promoter-binding and repression of PDGFRB by c-Myc are separable activities. We also show that Myc repression of PDGFRB is not dependent on previously described or known transactivator-binding regions, suggesting Myc may be recruited to the promoter by multiple or yet unidentified transcription factors. In the presence of intact promoter-binding by Myc, trichostatin A (TSA) can block Myc repression of PDGFRB in vivo, again demonstrating that promoter-binding and repression are separable. Taken together, we hypothesize that Myc repression of PDGFRB expression occurs by a multi-step mechanism in which repression is initiated after Myc is recruited to the promoter. PMID:15226411

  7. AMBRA1 links autophagy to cell proliferation and tumorigenesis by promoting c-MYC dephosphorylation and degradation

    PubMed Central

    Cianfanelli, Valentina; Fuoco, Claudia; Lorente, Mar; Salazar, Maria; Quondamatteo, Fabio; Gherardini, Pier Federico; De Zio, Daniela; Nazio, Francesca; Antonioli, Manuela; D’Orazio, Melania; Skobo, Tatjana; Bordi, Matteo; Rohde, Mikkel; Dalla Valle, Luisa; Helmer-Citterich, Manuela; Gretzmeier, Christine; Dengjel, Joern; Fimia, Gian Maria; Piacentini, Mauro; Di Bartolomeo, Sabrina; Velasco, Guillermo; Cecconi, Francesco

    2016-01-01

    Inhibition of a main regulator of cell metabolism, the protein kinase mTOR, induces autophagy and inhibits cell proliferation. However, the molecular pathways involved in the cross-talk between these two mTOR-dependent cell processes are largely unknown. Here we show that the scaffold protein AMBRA1, a member of the autophagy signalling network and a downstream target of mTOR, regulates cell proliferation by facilitating the dephosphorylation and degradation of the proto-oncogene C-MYC. We found that AMBRA1 favors the interaction between C-MYC and its phosphatase PP2A and that, when mTOR is inhibited, it enhances PP2A activity on this specific target, thereby reducing the cell division rate. As expected, such a de-regulation of C-MYC correlates with increased tumorigenesis in AMBRA1-defective systems, thus supporting a role for AMBRA1 as a haploinsufficient tumour suppressor gene. PMID:25438055

  8. High level amplification of N-MYC is not associated with adverse histology or outcome in primary retinoblastoma tumours

    PubMed Central

    Lillington, D M; Goff, L K; Kingston, J E; Onadim, Z; Price, E; Domizio, P; Young, B D

    2002-01-01

    Twenty-five primary retinoblastoma tumours were analysed by real-time quantitative polymerase chain reaction to determine the genomic copy number of the N-MYC gene (2p24) relative to the copy number for REL, B2M, ALB, AF10 and MLL. Twenty-one of these tumours were shown by Comparative Genomic Hybridization to contain variable copy number increases of chromosomal material mapping to 2p. High level amplification (>30-fold) of N-MYC was found in three tumours, none of which showed adverse histological features and all patients are surviving at between 54 and 108 months post enucleation. Furthermore, the three tumours associated with metastasis and adverse patient outcome showed normal N-MYC copy number. Although high level amplification of N-MYC is an unfavourable prognostic indicator in neuroblastoma, these data show no evidence of a correlation between amplification of N-MYC and adverse outcome in retinoblastoma. British Journal of Cancer (2002) 87, 779–782. doi:10.1038/sj.bjc.6600532 www.bjcancer.com © 2002 Cancer Research UK PMID:12232763

  9. Tristetraprolin is a tumor suppressor that impairs Myc-induced lymphoma and abolishes the malignant state

    PubMed Central

    Rounbehler, Robert J.; Fallahi, Mohammad; Yang, Chunying; Steeves, Meredith A.; Li, Weimin; Doherty, Joanne R.; Schaub, Franz X.; Sanduja, Sandhya; Dixon, Dan A.; Blackshear, Perry J.; Cleveland, John L.

    2012-01-01

    SUMMARY Myc oncoproteins directly regulate transcription by binding to target genes, yet this only explains a fraction of the genes affected by Myc. mRNA turnover is controlled via AU-binding proteins (AUBPs) that recognize AU-rich elements (AREs) found within many transcripts. Analyses of precancerous and malignant Myc-expressing B cells revealed that Myc regulates hundreds of ARE-containing (ARED) genes and select AUBPs. Notably, Myc directly suppresses transcription of Tristetraprolin (TTP/ZFP36), an mRNA-destabilizing AUBP, and this circuit is also operational during B lymphopoiesis and IL7 signaling. Importantly, TTP suppression is a hallmark of cancers with MYC involvement, and restoring TTP impairs Myc-induced lymphomagenesis and abolishes maintenance of the malignant state. Further, there is a selection for TTP loss in malignancy; thus, TTP functions as a tumor suppressor. Finally, Myc/TTP-directed control of select cancer-associated ARED genes is disabled during lymphomagenesis. Thus, Myc targets AUBPs to regulate ARED genes that control tumorigenesis. PMID:22863009

  10. c-Myc dependent initiation of genomic instability during neoplastic transformation.

    PubMed

    Taylor, C; Jalava, A; Mai, S

    1997-01-01

    The dihydrofolate reductase (DHFR) gene is a target of c-Myc in genomic instability. The induced overexpression of c-Myc in cell lines is followed by the amplification and rearrangement of the DHFR gene. Furthermore, the constitutive upregulation of c-Myc protein coincides with genomic instability of the DHFR gene in lymphoid, non-lymphoid and in tumor lines. The amplification of the DHFR gene is locus-specific and independent of species origins. We have now addressed the question whether inducible deregulation of c-Myc is followed by DHFR gene amplification in vivo. We show that the DHFR gene is a target of c-Myc-dependent neoplasia in vivo and propose a role for genomic instability during the initiation of neoplastic transformation. PMID:9308243