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Sample records for increased myc gene

  1. Using myc genes to search for stem cells in the ciliary margin of the Xenopus retina.

    PubMed

    Xue, Xiao Yan; Harris, William A

    2012-04-01

    The ciliary marginal zone (CMZ) of fish and frog retinas contains cells that proliferate throughout postembryonic development as the retina grows with increasing body size, indicating the presence of stem cells in this region. However, neither the location nor the molecular identity of retinal stem cells has been identified. Here, we show in Xenopus that c-myc and n-myc are sequentially expressed both during development and in the post-embryonic retina. The c-myc+/n-myc- cells near the extreme periphery of the CMZ cycle more slowly and preferentially retain DNA label compared to their more central cmyc+/n-myc+ neighbors which cycle rapidly and preferentially dilute DNA label. During retinal development c-myc is functionally required earlier than n-myc, and n-myc expression depends on earlier c-myc expression. The expression of c-myc but not n-myc in the CMZ depends on growth factor signaling. Our results suggest that c-myc+/n-myc- cells in the far peripheral CMZ are candidates for a niche-dependent population of retinal stem cells that give rise to more centrally located and rapidly dividing n-myc+ progenitors of more limited proliferative potential. Analysis of homologues of these genes in the zebrafish CMZ suggests that the transition from c-myc to n-myc expression might be conserved in other lower vertebrates whose retinas growth throughout life. Copyright © 2011 Wiley Periodicals, Inc.

  2. 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.

  3. Nucleotide sequence of the human N-myc gene

    SciTech Connect

    Stanton, L.W.; Schwab, M.; Bishop, J.M.

    1986-03-01

    Human neuroblastomas frequently display amplification and augmented expression of a gene known as N-myc because of its similarity to the protooncogene c-myc. It has therefore been proposed that N-myc is itself a protooncogene, and subsequent tests have shown that N-myc and c-myc have similar biological activities in cell culture. The authors have now detailed the kinship between N-myc and c-myc by determining the nucleotide sequence of human N-myc and deducing the amino acid sequence of the protein encoded by the gene. The topography of N-myc is strikingly similar to that of c-myc: both genes contain three exons of similar lengths; the coding elements of both genes are located in the second and third exons; and both genes have unusually long 5' untranslated regions in their mRNAs, with features that raise the possibility that expression of the genes may be subject to similar controls of translation. The resemblance between the proteins encoded by N-myc and c-myc sustains previous suspicions that the genes encode related functions.

  4. Zebra fish myc family and max genes: differential expression and oncogenic activity throughout vertebrate evolution.

    PubMed Central

    Schreiber-Agus, N; Horner, J; Torres, R; Chiu, F C; DePinho, R A

    1993-01-01

    To gain insight into the role of Myc family oncoproteins and their associated protein Max in vertebrate growth and development, we sought to identify homologs in the zebra fish (Brachydanio rerio). A combination of a polymerase chain reaction-based cloning strategy and low-stringency hybridization screening allowed for the isolation of zebra fish c-, N-, and L-myc and max genes; subsequent structural characterization showed a high degree of conservation in regions that encode motifs of known functional significance. On the functional level, zebra fish Max, like its mammalian counterpart, served to suppress the transformation activity of mouse c-Myc in rat embryo fibroblasts. In addition, the zebra fish c-myc gene proved capable of cooperating with an activated H-ras to effect the malignant transformation of mammalian cells, albeit with diminished potency compared with mouse c-myc. With respect to their roles in normal developing tissues, the differential temporal and spatial patterns of steady-state mRNA expression observed for each zebra fish myc family member suggest unique functions for L-myc in early embryogenesis, for N-myc in establishment and growth of early organ systems, and for c-myc in increasingly differentiated tissues. Furthermore, significant alterations in the steady-state expression of zebra fish myc family genes concomitant with relatively constant max expression support the emerging model of regulation of Myc function in cellular growth and differentiation. Images PMID:8474440

  5. N-Myc overexpression increases cisplatin resistance in neuroblastoma via deregulation of mitochondrial dynamics

    PubMed Central

    Casinelli, Gabriella; LaRosa, Jeff; Sharma, Manika; Cherok, Edward; Banerjee, Swati; Branca, Maria; Edmunds, Lia; Wang, Yudong; Sims-Lucas, Sunder; Churley, Luke; Kelly, Samantha; Sun, Ming; Stolz, Donna; Graves, J Anthony

    2016-01-01

    N-Myc is a global transcription factor that regulates the expression of genes involved in a number of essential cellular processes including: ribosome biogenesis, cell cycle and apoptosis. Upon deregulation, N-Myc can drive pathologic expression of many of these genes, which ultimately defines its oncogenic potential. Overexpression of N-Myc has been demonstrated to contribute to tumorigenesis, most notably for the pediatric tumor, neuroblastoma. Herein, we provide evidence that deregulated N-Myc alters the expression of proteins involved in mitochondrial dynamics. We found that N-Myc overexpression leads to increased fusion of the mitochondrial reticulum secondary to changes in protein expression due to aberrant transcriptional and post-translational regulation. We believe the structural changes in the mitochondrial network in response to N-Myc amplification in neuroblastoma contributes to two important aspects of tumor development and maintenance—bioenergetic alterations and apoptotic resistance. Specifically, we found that N-Myc overexpressing cells are resistant to programmed cell death in response to exposure to low doses of cisplatin, and demonstrated that this was dependent on increased mitochondrial fusion. We speculate that these changes in mitochondrial structure and function may contribute significantly to the aggressive clinical ph9enotype of N-Myc amplified neuroblastoma. PMID:28028439

  6. Myc

    PubMed Central

    Wasylishen, Amanda R.; Penn, Linda Z.

    2010-01-01

    The iconic history of the Myc oncoprotein encompasses 3 decades of intense scientific discovery. There is no question that Myc has been a pioneer, advancing insight into the molecular basis of cancer as well as functioning as a critical control center for several diverse biological processes and regulatory mechanisms. This narrative chronicles the journey and milestones that have defined the understanding of Myc, and it provides an opportunity to consider future directions in this challenging yet rewarding field. PMID:21779457

  7. Regulation of cyclin D2 gene expression by the Myc/Max/Mad network: Myc-dependent TRRAP recruitment and histone acetylation at the cyclin D2 promoter

    PubMed Central

    Bouchard, Caroline; Dittrich, Oliver; Kiermaier, Astrid; Dohmann, Karen; Menkel, Annette; Eilers, Martin; Lüscher, Bernhard

    2001-01-01

    Myc oncoproteins promote cell cycle progression in part through the transcriptional up-regulation of the cyclin D2 gene. We now show that Myc is bound to the cyclin D2 promoter in vivo. Binding of Myc induces cyclin D2 expression and histone acetylation at a single nucleosome in a MycBoxII/TRRAP-dependent manner. Down-regulation of cyclin D2 mRNA expression in differentiating HL60 cells is preceded by a switch of promoter occupancy from Myc/Max to Mad/Max complexes, loss of TRRAP binding, increased HDAC1 binding, and histone deacetylation. Thus, recruitment of TRRAP and regulation of histone acetylation are critical for transcriptional activation by Myc. PMID:11511535

  8. Kinetics of myc-max-mad gene expression during hepatocyte proliferation in vivo: Differential regulation of mad family and stress-mediated induction of c-myc.

    PubMed

    Mauleon, Itsaso; Lombard, Marie-Noëlle; Muñoz-Alonso, Maria J; Cañelles, Matilde; Leon, Javier

    2004-02-01

    Mad proteins (Mad1, Mxi1, Mad3, Mad4, Mnt/Rox) are biochemical and biological antagonists of c-Myc oncoprotein. Mad-Max dimers repress the transcription of the same target genes activated by Myc-Max dimers. Despite the critical role of Max and Mad proteins as modulators of c-Myc functions, there are no comparative data on their regulation in vivo. We carried out a systematic analysis of c-myc, max, and mad family expression in a model of synchronized cell proliferation in vivo in adult tissues, that is, rat hepatocytes after partial hepatectomy. We confirmed the previously reported early peak of c-myc expression after hepatectomy but we show that it did not correlate with hepatocyte proliferation as it also occurred in sham-operated animals as a result of surgical stresses. A second peak of c-myc expression was observed later, at the time of the wave of DNA synthesis. No such expression was detected in sham-operated rat quiescent hepatocytes. max expression increased around 4-16 h after hepatectomy, before the peaks of c-myc and DNA synthesis. mxi1 and mad4 were slightly downregulated during liver regeneration. mnt/rox expression did not change. These expression patterns suggest a role of Myc-Max for efficient mitogenic response of hepatocytes. We also analyzed the effects of Myc and Max ectopic expression on the clonogenic growth of the rat hepatoma cells. Expression of c-Myc and Max increased clonogenic growth, whereas the reduction of c-Myc levels by an antisense vector decreased growth. The results suggest nonredundant roles for mad genes in hepatocyte proliferation and point to c-Myc as a putative target for anticancer therapy of liver cancer.

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

    PubMed Central

    2011-01-01

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

  10. Drosophila Myc is required for normal DREF gene expression.

    PubMed

    Thao, Dang Thi Phuong; 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(4)/Y hemizygous mutant larvae demonstrated no maternal dMyc and severe impairment of dDREF mRNA transcription. dMyc loss of function in dm(2)/dm(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.

  11. 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.

  12. Organization and expression of the chicken N-myc gene.

    PubMed

    Sawai, S; Kato, K; Wakamatsu, Y; Kondoh, H

    1990-05-01

    We cloned the chicken N-myc gene and analyzed its structure and expression. We found that it consisted of three exons with coding regions in exons 2 and 3. Comparison to mammalian N-myc genomic sequence indicated that nucleotide sequences of the 5'-flanking region, noncoding exon 1, and introns were not conserved, but coding and 3' noncoding sequences showed significant homology to mammalian N-myc. Alignment of deduced amino acid sequences of chicken and mammalian N-myc proteins revealed nine conserved domains interrupted by different lengths of nonhomologous sequences. Two of the domains were specific to N-myc proteins, and the other seven were common to c-myc proteins. Northern blot (immunoblot) and in situ hybridization analyses of 3.5-day-old chicken embryos revealed that high-level expression of the N-myc gene was confirmed to certain tissues, e.g., the central nervous system, neural crest derivatives, and mesenchyme of limb buds. In the beak and limb primordia, N-myc expression in the mesenchyme was higher toward the distal end, suggesting possible involvement in positional assignment of the tissue within the rudimentary structures.

  13. Modeling and Targeting MYC Genes in Childhood Brain Tumors.

    PubMed

    Hutter, Sonja; Bolin, Sara; Weishaupt, Holger; Swartling, Fredrik J

    2017-03-23

    Brain tumors are the second most common group of childhood cancers, accounting for about 20%-25% of all pediatric tumors. Deregulated expression of the MYC family of transcription factors, particularly c-MYC and MYCN genes, has been found in many of these neoplasms, and their expression levels are often correlated with poor prognosis. Elevated c-MYC/MYCN initiates and drives tumorigenesis in many in vivo model systems of pediatric brain tumors. Therefore, inhibition of their oncogenic function is an attractive therapeutic target. In this review, we explore the roles of MYC oncoproteins and their molecular targets during the formation, maintenance, and recurrence of childhood brain tumors. We also briefly summarize recent progress in the development of therapeutic approaches for pharmacological inhibition of MYC activity in these tumors.

  14. Modeling and Targeting MYC Genes in Childhood Brain Tumors

    PubMed Central

    Hutter, Sonja; Bolin, Sara; Weishaupt, Holger; Swartling, Fredrik J.

    2017-01-01

    Brain tumors are the second most common group of childhood cancers, accounting for about 20%–25% of all pediatric tumors. Deregulated expression of the MYC family of transcription factors, particularly c-MYC and MYCN genes, has been found in many of these neoplasms, and their expression levels are often correlated with poor prognosis. Elevated c-MYC/MYCN initiates and drives tumorigenesis in many in vivo model systems of pediatric brain tumors. Therefore, inhibition of their oncogenic function is an attractive therapeutic target. In this review, we explore the roles of MYC oncoproteins and their molecular targets during the formation, maintenance, and recurrence of childhood brain tumors. We also briefly summarize recent progress in the development of therapeutic approaches for pharmacological inhibition of MYC activity in these tumors. PMID:28333115

  15. 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

  16. Sonic hedgehog elevates N-myc gene expression in neural stem cells.

    PubMed

    Liu, Dongsheng; Wang, Shouyu; Cui, Yan; Shen, Lun; Du, Yanping; Li, Guilin; Zhang, Bo; Wang, Renzhi

    2012-08-05

    Proliferation of neural stem cells is regulated by the secreted signaling molecule sonic hedgehog. In this study, neural stem cells were infected with recombinant adeno-associated virus expressing sonic hedgehog-N-enhanced green fluorescent protein. The results showed that overexpression of sonic hedgehog in neural stem cells induced the increased expression of Gli1 and N-myc, a target gene of sonic hedgehog. These findings suggest that N-myc is a direct downstream target of the sonic hedgehog signal pathway in neural stem cells. Sonic hedgehog and N-myc are important mediators of sonic hedgehog-induced proliferation of neural stem cells.

  17. HMG-I/Y, a New c-Myc Target Gene and Potential Oncogene

    PubMed Central

    Wood, Lisa J.; Mukherjee, Mita; Dolde, Christine E.; Xu, Yi; Maher, Joseph F.; Bunton, Tracie E.; Williams, John B.; Resar, Linda M. S.

    2000-01-01

    The HMG-I/Y gene encodes the HMG-I and HMG-Y proteins, which function as architectural chromatin binding proteins important in the transcriptional regulation of several genes. Although increased expression of the HMG-I/Y proteins is associated with cellular proliferation, neoplastic transformation, and several human cancers, the role of these proteins in the pathogenesis of malignancy remains unclear. To better understand the role of these proteins in cell growth and transformation, we have been studying the regulation and function of HMG-I/Y. The HMG-I/Y promoter was cloned, sequenced, and subjected to mutagenesis analysis. A c-Myc–Max consensus DNA binding site was identified as an element important in the serum stimulation of HMG-I/Y. The oncoprotein c-Myc and its protein partner Max bind to this site in vitro and activate transcription in transfection experiments. HMG-I/Y expression is stimulated by c-Myc in a Myc-estradiol receptor cell line in the presence of the protein synthesis inhibitor cycloheximide, indicating that HMG-I/Y is a direct c-Myc target gene. HMG-I/Y induction is decreased in Myc-deficient fibroblasts. HMG-I/Y protein expression is also increased in Burkitt's lymphoma cell lines, which are known to have increased c-Myc protein. Like Myc, increased expression of HMG-I protein leads to the neoplastic transformation of both Rat 1a fibroblasts and CB33 cells. In addition, Rat 1a cells overexpressing HMG-I protein form tumors in nude mice. Decreasing HMG-I/Y proteins using an antisense construct abrogates transformation in Burkitt's lymphoma cells. These findings indicate that HMG-I/Y is a c-Myc target gene involved in neoplastic transformation and a member of a new class of potential oncogenes. PMID:10891489

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

    PubMed

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

    2015-11-03

    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.

  19. DNA replication origin and transcriptional enhancer in c-myc gene share the c-myc protein binding sequences.

    PubMed Central

    Ariga, H; Imamura, Y; Iguchi-Ariga, S M

    1989-01-01

    We have previously reported that c-myc protein, or protein(s) complexed with c-myc protein, binds to the region upstream of the first exon of the c-myc gene and that this region contains an origin of cellular DNA replication (ori) and also a transcriptional enhancer. Here we show by Southwestern blotting that c-myc protein binds directly to a 7 bp sequence within the above region. Furthermore, we show that the c-myc protein binding sequences are indispensable for both ori and enhancer functions, but that additional sequences are required for maximal ori and enhancer activities. Thus, c-myc protein is a sequence specific factor which is apparently used both in initiation of DNA replication and in regulation of RNA transcription. Images PMID:2686984

  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. Genomic characterisation of Eμ-Myc mouse lymphomas identifies Bcor as a Myc co-operative tumour-suppressor gene.

    PubMed

    Lefebure, Marcus; Tothill, Richard W; Kruse, Elizabeth; Hawkins, Edwin D; Shortt, Jake; Matthews, Geoffrey M; Gregory, Gareth P; Martin, Benjamin P; Kelly, Madison J; Todorovski, Izabela; Doyle, Maria A; Lupat, Richard; Li, Jason; Schroeder, Jan; Wall, Meaghan; Craig, Stuart; Poortinga, Gretchen; Cameron, Don; Bywater, Megan; Kats, Lev; Gearhart, Micah D; Bardwell, Vivian J; Dickins, Ross A; Hannan, Ross D; Papenfuss, Anthony T; Johnstone, Ricky W

    2017-03-06

    The Eμ-Myc mouse is an extensively used model of MYC driven malignancy; however to date there has only been partial characterization of MYC co-operative mutations leading to spontaneous lymphomagenesis. Here we sequence spontaneously arising Eμ-Myc lymphomas to define transgene architecture, somatic mutations, and structural alterations. We identify frequent disruptive mutations in the PRC1-like component and BCL6-corepressor gene Bcor. Moreover, we find unexpected concomitant multigenic lesions involving Cdkn2a loss and other cancer genes including Nras, Kras and Bcor. These findings challenge the assumed two-hit model of Eμ-Myc lymphoma and demonstrate a functional in vivo role for Bcor in suppressing tumorigenesis.

  2. Genomic characterisation of Eμ-Myc mouse lymphomas identifies Bcor as a Myc co-operative tumour-suppressor gene

    PubMed Central

    Lefebure, Marcus; Tothill, Richard W.; Kruse, Elizabeth; Hawkins, Edwin D.; Shortt, Jake; Matthews, Geoffrey M.; Gregory, Gareth P.; Martin, Benjamin P.; Kelly, Madison J.; Todorovski, Izabela; Doyle, Maria A.; Lupat, Richard; Li, Jason; Schroeder, Jan; Wall, Meaghan; Craig, Stuart; Poortinga, Gretchen; Cameron, Don; Bywater, Megan; Kats, Lev; Gearhart, Micah D.; Bardwell, Vivian J.; Dickins, Ross A.; Hannan, Ross D.; Papenfuss, Anthony T.; Johnstone, Ricky W.

    2017-01-01

    The Eμ-Myc mouse is an extensively used model of MYC driven malignancy; however to date there has only been partial characterization of MYC co-operative mutations leading to spontaneous lymphomagenesis. Here we sequence spontaneously arising Eμ-Myc lymphomas to define transgene architecture, somatic mutations, and structural alterations. We identify frequent disruptive mutations in the PRC1-like component and BCL6-corepressor gene Bcor. Moreover, we find unexpected concomitant multigenic lesions involving Cdkn2a loss and other cancer genes including Nras, Kras and Bcor. These findings challenge the assumed two-hit model of Eμ-Myc lymphoma and demonstrate a functional in vivo role for Bcor in suppressing tumorigenesis. PMID:28262675

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

    PubMed

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

    2003-05-23

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

  4. Human differentiation-related gene NDRG1 is a Myc downstream-regulated gene that is repressed by Myc on the core promoter region.

    PubMed

    Zhang, Jian; Chen, Suning; Zhang, Wei; Zhang, Jing; Liu, Xinping; Shi, Hai; Che, Honglei; Wang, Weizhong; Li, Fuyang; Yao, Libo

    2008-07-01

    N-Myc downstream-regulated gene 1 (ndrg1) is up-regulated in N-Myc knockout mouse embryos. The human NDRG family consists of 4 highly homologous members and human Ndrg1 exhibits approximately 94% homology with mouse ndrg1. However, the regulatory mechanism of NDRG1 via Myc repression is as yet unknown. We previously identified human NDRG2 and demonstrated that this gene is transcriptionally down-regulated by Myc via Miz-1-dependent interaction with the core promoter region of NDRG2. Here, we provide evidence that human NDRG1 is regulated by Myc in a manner similar to NDRG2. We found that Ndrg1 expression levels were enhanced as Myc expression declined in differentiated cells, but were down-regulated following Myc induction. The data revealed that both N-Myc and c-Myc can repress human NDRG1 at the transcriptional level. We further determined that the core promoter region of human NDRG1 is required for Myc repression, and verified the interaction of Myc with the core promoter region. However, the presence of the protein synthesis inhibitor cycloheximide could reverse the repression of Myc, indicating the indirect repression of human NDRG1 by Myc. Moreover, we found that c-Myc-mediated repression can be inhibited by TSA, an HDACs inhibitor, which suggests the involvement of HDACs in the repression process. Taken together, our results demonstrate that, in common with NDRG2, human NDRG1 can be indirectly transcriptionally down-regulated by Myc via interaction with the NDRG1 core promoter.

  5. Analyzing Myc in Cell Transformation and Evolution

    PubMed Central

    Hartl, Markus; Bister, Klaus

    2017-01-01

    The myc oncogene was originally identified as a transduced allele (v-myc) in the genome of a highly oncogenic avian retrovirus. The protein product (Myc) of the cellular c-myc protooncogene represents the key component of a transcription factor network controlling the expression of a large fraction of all human genes. Myc regulates fundamental cellular processes like growth control, metabolism, proliferation, differentiation, and apoptosis. Mutational deregulation of c-myc leading to increased levels of the Myc protein is a frequent event in the etiology of human cancers. In this chapter, we describe cell systems and experimental strategies to monitor and quantify the oncogenic potential of myc alleles, and to isolate and characterize transcriptional targets of Myc that are relevant for the cell transformation process. We also describe experimental procedures to study the evolutionary origin of myc and to analyze structure and function of the ancestral myc protooncogenes. PMID:24006056

  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. MYC and Human Telomerase Gene (TERC) Copy Number Gain in Early-stage Non–small Cell Lung Cancer

    PubMed Central

    Flacco, Antonella; Ludovini, Vienna; Bianconi, Fortunato; Ragusa, Mark; Bellezza, Guido; Tofanetti, Francesca R.; Pistola, Lorenza; Siggillino, Annamaria; Vannucci, Jacopo; Cagini, Lucio; Sidoni, Angelo; Puma, Francesco; Varella-Garcia, Marileila; Crinò, Lucio

    2015-01-01

    Objectives We investigated the frequency of MYC and TERC increased gene copy number (GCN) in early-stage non–small cell lung cancer (NSCLC) and evaluated the correlation of these genomic imbalances with clinicopathologic parameters and outcome. Materials and Methods Tumor tissues were obtained from 113 resected NSCLCs. MYC and TERC GCNs were tested by fluorescence in situ hybridization (FISH) according to the University of Colorado Cancer Center (UCCC) criteria and based on the receiver operating characteristic (ROC) classification. Results When UCCC criteria were applied, 41 (36%) cases for MYC and 41 (36%) cases for TERC were considered FISH-positive. MYC and TERC concurrent FISH-positive was observed in 12 cases (11%): 2 (17%) cases with gene amplification and 10 (83%) with high polysomy. By using the ROC analysis, high MYC (mean ≥2.83 copies/cell) and TERC (mean ≥2.65 copies/cell) GCNs were observed in 60 (53.1%) cases and 58 (51.3%) cases, respectively. High TERC GCN was associated with squamous cell carcinoma (SCC) histology (P = 0.001). In univariate analysis, increased MYC GCN was associated with shorter overall survival (P = 0.032 [UCCC criteria] or P = 0.02 [ROC classification]), whereas high TERC GCN showed no association. In multivariate analysis including stage and age, high MYC GCN remained significantly associated with worse overall survival using both the UCCC criteria (P = 0.02) and the ROC classification (P = 0.008). Conclusions Our results confirm MYC as frequently amplified in early-stage NSCLC and increased MYC GCN as a strong predictor of worse survival. Increased TERC GCN does not have prognostic impact but has strong association with squamous histology. PMID:25806711

  8. Expression analysis of MYC genes from Tamarix hispida in response to different abiotic stresses.

    PubMed

    Ji, Xiaoyu; Wang, Yucheng; Liu, Guifeng

    2012-01-01

    The MYC genes are a group of transcription factors containing both bHLH and ZIP motifs that play important roles in the regulation of abscisic acid (ABA)-responsive genes. In the present study, to investigate the roles of MYC genes under NaCl, osmotic and ABA stress conditions, nine MYC genes were cloned from Tamarix hispida. Real-time reverse-transcriptase (RT)-PCR showed that all nine MYC genes were expressed in root, stem and leaf tissues, but that the levels of the transcripts of these genes in the various tissues differed notably. The MYC genes were highly induced in the roots in response to ABA, NaCl and osmotic stresses after 3 h; however, in the stem and leaf tissues, MYC genes were highly induced only when exposed to these stresses for 6 h. In addition, most of these MYC genes were highly expressed in roots in comparison with stems and leaves. Furthermore, the MYC genes were more highly induced in roots than in stem and leaf tissues, indicating that these genes may play roles in stress responses mainly in the roots rather than the stems and leaves. The results of this present study suggest that MYCs are involved in salt and osmotic stress tolerances and are controlled by the ABA signal transduction pathway.

  9. Low-level copy number changes of MYC genes have a prognostic impact in medulloblastoma.

    PubMed

    Zitterbart, Karel; Filkova, Hana; Tomasikova, Lenka; Necesalova, Eva; Zambo, Iva; Kantorova, Dagmar; Slamova, Iva; Vranova, Vladimira; Zezulkova, Dita; Pesakova, Martina; Pavelka, Zdenek; Veselska, Renata; Kuglik, Petr; Sterba, Jaroslav

    2011-03-01

    High-level amplifications of MYC genes are associated with poor outcomes in childhood medulloblastoma (MB). However, the occurrence of MYCN and MYCC copy number increases below the intense amplification pattern is rarely reported, and its clinical impact has not yet been determined. Here, we describe this phenomenon and its prognostic significance in a cohort of 29 MB patients. Using interphase fluorescence in situ hybridization (I-FISH), low-level copy number alterations, i.e. gain of MYCN, were shown in 5/27 (19%) samples, whereas amplification was revealed in only 1/27 (4%) samples. MYCC gain was revealed in 6/29 (21%) MB, while amplification was disclosed in only 2/29 (7%). Hyperploidy and co-incidence of gains in both MYC loci were frequently observed in samples with copy number aberrations. Survival analysis has clearly shown that MYC copy number increases are associated with lowered event-free survival and overall survival in MB. In the case of MYCN, this negative correlation was statistically significant. We conclude that limited numerical alterations in loci 2p24 (MYCN) and 8q24 (MYCC), as assessed by I-FISH, are present in MB with a higher frequency than high-level amplifications. Poor prognoses were observed in patients with copy number increases in MYC genes. Our data illustrate the importance of further investigations in multicenter trials to better refine the emerging genomic-based prognostic stratification in MB.

  10. 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

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

    PubMed

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

    2016-12-20

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

  13. 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.

  14. 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.

  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. MYC Degradation

    PubMed Central

    Farrell, Amy S.; Sears, Rosalie C.

    2014-01-01

    The MYC oncoprotein is an essential transcription factor that regulates the expression of many genes involved in cell growth, proliferation, and metabolic pathways. Thus, it is important to keep MYC activity in check in normal cells in order to avoid unwanted oncogenic changes. Normal cells have adapted several ways to control MYC levels, and these mechanisms can be disrupted in cancer cells. One of the major ways in which MYC levels are controlled in cells is through targeted degradation by the ubiquitin–proteasome system (UPS). Here, we discuss the role of the UPS in the regulation of MYC protein levels and review some of the many proteins that have been shown to regulate MYC protein stability. In addition, we discuss how this relates to MYC transcriptional activity, human cancers, and therapeutic targeting. PMID:24591536

  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. SRC-2-mediated coactivation of anti-tumorigenic target genes suppresses MYC-induced liver cancer

    PubMed Central

    Zhou, Xiaorong; Comerford, Sarah A.; York, Brian; O’Donnell, Kathryn A.

    2017-01-01

    Hepatocellular carcinoma (HCC) is the fifth most common solid tumor in the world and the third leading cause of cancer-associated deaths. A Sleeping Beauty-mediated transposon mutagenesis screen previously identified mutations that cooperate with MYC to accelerate liver tumorigenesis. This revealed a tumor suppressor role for Steroid Receptor Coactivator 2/Nuclear Receptor Coactivator 2 (Src-2/Ncoa2) in liver cancer. In contrast, SRC-2 promotes survival and metastasis in prostate cancer cells, suggesting a tissue-specific and context-dependent role for SRC-2 in tumorigenesis. To determine if genetic loss of SRC-2 is sufficient to accelerate MYC-mediated liver tumorigenesis, we bred Src-2-/- mice with a MYC-induced liver tumor model and observed a significant increase in liver tumor burden. RNA sequencing of liver tumors and in vivo chromatin immunoprecipitation assays revealed a set of direct target genes that are bound by SRC-2 and exhibit downregulated expression in Src-2-/- liver tumors. We demonstrate that activation of SHP (Small Heterodimer Partner), DKK4 (Dickkopf-4), and CADM4 (Cell Adhesion Molecule 4) by SRC-2 suppresses tumorigenesis in vitro and in vivo. These studies suggest that SRC-2 may exhibit oncogenic or tumor suppressor activity depending on the target genes and nuclear receptors that are expressed in distinct tissues and illuminate the mechanisms of tumor suppression by SRC-2 in liver. PMID:28273073

  19. MYC Deregulation in Primary Human Cancers

    PubMed Central

    Kalkat, Manpreet; De Melo, Jason; Hickman, Katherine Ashley; Lourenco, Corey; Redel, Cornelia; Resetca, Diana; Tamachi, Aaliya; Tu, William B.; Penn, Linda Z.

    2017-01-01

    MYC regulates a complex biological program by transcriptionally activating and repressing its numerous target genes. As such, MYC is a master regulator of many processes, including cell cycle entry, ribosome biogenesis, and metabolism. In cancer, the activity of the MYC transcriptional network is frequently deregulated, contributing to the initiation and maintenance of disease. Deregulation often leads to constitutive overexpression of MYC, which can be achieved through gross genetic abnormalities, including copy number alterations, chromosomal translocations, increased enhancer activity, or through aberrant signal transduction leading to increased MYC transcription or increased MYC mRNA and protein stability. Herein, we summarize the frequency and modes of MYC deregulation and describe both well-established and more recent findings in a variety of cancer types. Notably, these studies have highlighted that with an increased appreciation for the basic mechanisms deregulating MYC in cancer, new therapeutic vulnerabilities can be discovered and potentially exploited for the inhibition of this potent oncogene in cancer. PMID:28587062

  20. [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.

  1. 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.

  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. Insertional mutagenesis reveals progression genes and checkpoints in MYC/Runx2 lymphomas

    PubMed Central

    2008-01-01

    In this study we have exploited the power of insertional mutagenesis to elucidate tumor progression pathways in mice carrying two oncogenes (MYC/Runx2) that collaborate to drive early lymphoma development. Neonatal infection of these mice with Moloney murine leukemia virus (MLV) resulted in accelerated tumor onset with associated increases in clonal complexity and lymphoid dissemination. Large-scale analysis of retroviral integration sites in these tumors revealed a profound bias towards a narrow range of target genes including Jdp2 (Jundm2), D cyclin and Pim family genes. Remarkably, direct PCR analysis of integration hot-spots revealed that every progressing tumor consisted of multiple clones harbouring hits at these loci, giving access to large numbers of independent insertion events and uncovering the contrasting mutagenic mechanisms operating at each target gene. Direct PCR analysis showed that high frequency targeting occurs only in the tumor environment in vivo and is specific for the progression gene set. These results indicate that early lymphomas in MYC/Runx2 mice remain dependent on exogenous growth signals and that progression can be achieved by constitutive activation of pathways converging on a cell cycle checkpoint that acts as the major rate-limiting step for lymphoma outgrowth. PMID:17545590

  4. Regulation of translocated c-myc genes transfected into plasmacytoma cells

    SciTech Connect

    Feo, S.; Harvey, R.; Showe, L.; Croce, C.M.

    1986-02-01

    The authors have transfected two translocated c-myc oncogene clones, derived from two human lymphomas carrying the t(8;14) chromosome translocation, into mouse plasmacytoma cells to study the regulation of their expression. In one case, the transfected clone contained the two coding exons of the c-myc oncogene translocated to an immunoglobulin heavy-chain switch region; in the other case, the two coding exons were translocated 5' of the enhancer element located between the heavy-chain joining region (J/sub H/) and the switch region S/sub ..mu../. Nuclease S1 protection experiments indicate that only the c-myc translocated 5' of the enhancer element is transcribed in the plasmacytoma cells. Thus, 5'-truncation of the c-myc gene per se does not lead to c-myc deregulation. Further, since the level of c-myc transcripts in the parental human lymphoma cells was 3- to 4-fold higher than in the transfectants, it seems likely that additional elements within the heavy-chain locus may play a role in the enhancement of c-myc gene transcription in lymphoma cells.

  5. Burkitt lymphoma beyond MYC translocation: N-MYC and DNA methyltransferases dysregulation.

    PubMed

    De Falco, Giulia; Ambrosio, Maria Raffaella; Fuligni, Fabio; Onnis, Anna; Bellan, Cristiana; Rocca, Bruno Jim; Navari, Mohsen; Etebari, Maryam; Mundo, Lucia; Gazaneo, Sara; Facchetti, Fabio; Pileri, Stefano A; Leoncini, Lorenzo; Piccaluga, Pier Paolo

    2015-10-09

    The oncogenic transcription factor MYC is pathologically activated in many human malignancies. A paradigm for MYC dysregulation is offered by Burkitt lymphoma, where chromosomal translocations leading to Immunoglobulin gene-MYC fusion are the crucial initiating oncogenic events. However, Burkitt lymphoma cases with no detectable MYC rearrangement but maintaining MYC expression have been identified and alternative mechanisms can be involved in MYC dysregulation in these cases. We studied the microRNA profile of MYC translocation-positive and MYC translocation-negative Burkitt lymphoma cases in order to uncover possible differences at the molecular level. Data was validated at the mRNA and protein level by quantitative Real-Time polymerase chain reaction and immunohistochemistry, respectively. We identified four microRNAs differentially expressed between the two groups. The impact of these microRNAs on the expression of selected genes was then investigated. Interestingly, in MYC translocation-negative cases we found over-expression of DNA-methyl transferase family members, consistent to hypo-expression of the hsa-miR-29 family. This finding suggests an alternative way for the activation of lymphomagenesis in these cases, based on global changes in methylation landscape, aberrant DNA hypermethylation, lack of epigenetic control on transcription of targeted genes, and increase of genomic instability. In addition, we observed an over-expression of another MYC family gene member, MYCN that may therefore represent a cooperating mechanism of MYC in driving the malignant transformation in those cases lacking an identifiable MYC translocation but expressing the gene at the mRNA and protein levels. Collectively, our results showed that MYC translocation-positive and MYC translocation-negative Burkitt lymphoma cases are slightly different in terms of microRNA and gene expression. MYC translocation-negative Burkitt lymphoma, similarly to other aggressive B-cell non Hodgkin

  6. Emerging role of N-myc downstream-regulated gene 2 (NDRG2) in cancer

    PubMed Central

    Ma, Zhiqiang; Yan, Xiaolong; Di, Shouyin; Jiang, Shuai; Li, Tian; Cheng, Yedong; Yang, Yang

    2016-01-01

    N-myc downstream-regulated gene 2 (NDRG2) is a tumor suppressor and cell stress-related gene. NDRG2 is associated with tumor incidence, progression, and metastasis. NDRG2 regulates tumor-associated genes and is regulated by multiple conditions, treatments, and protein/RNA entities, including hyperthermia, trichostatin A and 5-aza-2′-deoxycytidine, which are promising potential cancer therapeutics. In this review, we discuss the expression as well as the clinical and pathological significance of NDRG2 in cancer. The pathological processes and molecular pathways regulated by NDRG2 are also summarized. Moreover, mechanisms for increasing NDRG2 expression in tumors and the potential directions of future NDRG2 research are discussed. The information reviewed here should assist in experimental design and increase the potential of NDRG2 as a therapeutic target for cancer. PMID:26506239

  7. TGFβ-dependent gene expression shows that senescence correlates with abortive differentiation along several lineages in Myc-induced lymphomas.

    PubMed

    Müller, Judith; Samans, Birgit; van Riggelen, Jan; Fagà, Giovanni; Peh K N, Raquel; Wei, Chia-Lin; Müller, Heiko; Amati, Bruno; Felsher, Dean; Eilers, Martin

    2010-12-01

    Deregulated expression of Myc under the control of an immunoglobulin enhancer induces lymphoma formation in mice. The development of lymphomas is limited by TGFβ-dependent senescence and high levels of Myc expression are continuously required to antagonize senescence. The biological processes underlying senescence are not fully resolved. We report here a comprehensive analysis of TGFβ-dependent alterations in gene expression when the Myc transgene is switched off. Our data show that Myc-induced target genes are downregulated in a TGFβ-independent manner. In contrast, TGFβ is required to upregulate a broad spectrum of genes that are characteristic of different T-cell lineages when Myc is turned off. The analysis reveals a significant overlap between these Myc-repressed genes with genes that are targets of polycomb repressive complexes in embryonic stem cells. Therefore, TGFβ-dependent senescence is associated with gene expression patterns indicative of abortive cellular differentiation along several lineages.

  8. Detection of hTERC and c-MYC genes in cervical epithelial exfoliated cells for cervical cancer screening.

    PubMed

    Li, Tian; Tang, Liangdan; Bian, Duhong; Jia, Ying; Huang, Xin; Zhang, Xinhua

    2014-05-01

    Cervical cancer is the principal cause of mortality due to cancer in women worldwide. New predictive markers may increase survival rates by improving the treatment of patients at a high risk for cancer. This study was carried out to investigate the amplification of human telomerase RNA component (hTERC) or/and c-MYC in cervical epithelial exfoliated cells for cervical carcinoma screening. We collected 171 specimens. including speciments from normal cervix, benign lesions, cervical intraepithelial neoplasia (CIN)1, CIN2 and CIN3, or carcinoma in situ, as well as invasive cervical squamous cell carcinoma. Fluorescence in situ hybridization (FISH) was performed to detect alterations in hTERC and c-MYC expression. We analyzed the area under the receiver operating characteristic (ROC) curve (AUC), as well as the sensitivity and specificity of single screening and conjoined screening. There was a trend toward an increasing amplification of 2 genes with the increasing severity of cervical lesions. ROC curve analysis demonstrated that the AUC values of the hTERC gene for the screening of different cervical lesions were >0.8. Compared with the hTERC gene, the AUC of the c-MYC gene for the screening of ≥CIN3 was >0.8 and the AUC for the screening of other cervical lesions was >0.7. For the screening of cervical lesions above the grade of benign lesions, cytological diagnosis was superior to the gene detection with significant differences. For the screening of cervical lesions >CIN1, there were no statistically significant differences (P>0.05) between the hTERC gene and cytological diagnosis, whereas the screening results of c-MYC detection and cytological diagnosis differed significantly (P<0.05). For the screening of cervical lesions >CIN2 or >CIN3, the detection of hTERC and c-MYC genes and cytological diagnosis had similar screening results with no statistically significant differences (P>0.05). In conclusion, using FISH to detect the amplification of hTERC or/and c-MYC

  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. Ratcheting Myc

    PubMed Central

    Freie, Brian W.; Eisenman, Robert N.

    2017-01-01

    In this issue of Cancer Cell, Murphy et al. describe a mouse model designed to examine the biological effects of different levels of deregulated c-myc expression. They provide evidence that distinct threshold levels of Myc are required for increased proliferation and for apoptosis in different tissues. PMID:19061831

  11. 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.

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

    PubMed

    Hung, Le; Kumar, Vijay

    2006-05-26

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

  13. Clinical significance of hTERC and C-Myc genes amplification in a group of Egyptian patients with cancer cervix.

    PubMed

    Eid, M M; Nossair, H M; Ismael, M T; Amira, G; Hosney, M M; Abdul Rahman, R

    2011-07-01

    Cervical cancer is the second most common cancer in women worldwide after breast cancer. Cervical cancer is a preventable disease. The implementation of cervical cancer screening programs has greatly decreased the morbidity and mortality, as precancerous lesions and early invasive cervical cancer could be detected and treated effectively. The detection of hTERC gene amplification was suggested as a possible diagnostic marker for use in routine cytological screening. The present study was designed to detect genomic gains of the hTERC and C-MYC genes using FISH technique and to investigate the relationship between genes amplification and the clinical data of the patients. The current study was carried out on twelve cases with cervical cancer at different grades (three cases were grade I, six cases were grade II and three cases were grade III). Interphase FISH analysis using LSI probe, Cervical Cancer probe hTERC (3q26) & C-MYC (8q24), was successfully performed on 12 patients with cancer cervix. Interphase FISH analysis revealed positive hTERC gene amplification in all cases of cancer cervix (100%). However C-MYC gene amplification was detected in four cases only (33.3%). Statistical analysis of the data revealed significant correlation between hTERC amplification and grading. Also, there was significant correlation between C-MYC amplification and grading and highly significant correlation between C-MYC amplification and hTERC amplification. On the other hand hTERC and C-MYC genes amplification showed an inverse correlation with the ages of the patients. The present study highlights the importance of using hTERC and C-MYC genes FISH probes for cases with cancer cervix or pre-malignant lesions as a sensitive technique. This method provides an easy and effective applicable approach which helps in the diagnosis and prognosis, as an increased copy number is associated with a more advanced grade that could be detected in the early stages of the disease.

  14. 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.

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

    PubMed

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

    2006-12-10

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

  16. Differential activity of conditional MYC and its variant MYC-S in human mortal fibroblasts.

    PubMed

    Hirst, S K; Grandori, C

    2000-10-26

    We have explored the effects of the conditional MYC-estrogen receptor fusion protein, MYC-ERTM, in human mortal fibroblasts, WI38, on cell-cycle entry, apoptosis and gene expression. The results indicate that activation of MYC-ERTM in WI38 cells is sufficient to cause S phase entry of quiescent cells, which is preceded by phosphorylation of Rb and activation of the Cdk2-associated kinase. We also analysed the MYC protein variant, MYC-S, which lacks part of the transcriptional activation domain but includes the conserved MYC box II and 26 amino acids N-terminal to it. MYC-S was previously shown to promote proliferation and apoptosis of immortalized rodent cell lines. The results indicate that MYC-S has undetectable activity as an inducer of S phase or apoptosis of quiescent WI38 cells. However, Myc-S stimulates proliferation of WI38 cells in the presence of 10% fetal calf serum. Surprisingly, we found that MYC-S, previously considered solely a repressor of specific reporter genes, is instead a weak transactivator of endogenous target genes both in mortal and immortalized cells. In addition, MYC-S exhibit a weak repressor activity upon an endogenous target gene only in immortalized cells. MYC-S transcriptional properties suggest that MYC box II and the adjacent N-terminal amino acids, while not sufficient for full repression function, participate in transactivation of endogenous target genes.

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

    USDA-ARS?s Scientific Manuscript database

    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...

  18. 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

  19. Binding studies on peptide-oligonucleotide complex: intercalation of tryptophan in GC-rich region of c-myc gene.

    PubMed

    Jain, Akanchha Aklank; Rajeswari, Moganty R

    2003-07-23

    Transcriptional regulation of the c-myc gene is essential for normal cellular proliferation; differentiation and overexpression of c-myc is associated with several human cancers. C-myc gene, particularly exon 1, which contains the conserved P1 and P2 promoter regions, has been a potential target for the intercalating drugs in chemotherapy. We have chosen a 21-mer GC-rich oligonucleotide sequence starting from 2281 to 2302 of human c-myc gene located 26 base pair upstream of P1 promoter and partially overlapping with the TATA box of P1. In this paper, we have studied the interaction of a tetrapeptide, KWGK-otBut, with duplex of the above 21-mer sequence under low-salt conditions using UV-Vis absorption, UV melting, fluorescence and circular dichroic (CD) spectroscopy. From the fluorescence quenching data, we determined the two binding constants, K1 (involving only electrostatic interactions) and K2 (involving intercalation), for the formation of (PN)1 and (PN)2 of the two-step mechanism previously established by us. Significant changes were observed in the UV difference absorption spectra and CD spectra of both KWGK and 21-mer duplex upon complex formation even at a very low peptide to nucleotide (P/N) ratios. These spectral changes accompanied by a high value of K2 (=5.13) suggest a strong binding of KWGK involving intercalation of the tryptophan in 21-mer duplex. Based on the above data along with changes observed in deltaH, deltaS and deltaG and increase in melting temperature (by about 8 degrees C) of the 21-mer duplex in presence of KWGK, we propose a model for intercalation of tryptophan of in GC-rich region of c-myc gene. Present observations may be explored in understanding the role of intercalation in protein-nucleic acid interactions in c-myc expression and these results could also help in designing oligopeptides or other low molecular weight ligands to modulate gene expression.

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

    PubMed

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

    2013-03-14

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

  1. [Clinical characteristics and prognosis of concurrent positive t(14; 18) and myc gene rearrangement in diffuse large B cell lymphoma].

    PubMed

    Zhang, H W; Chen, Z W; Wang, L Y; He, J X; Zheng, Y P; Han, W E; Yang, B; Wang, Y L; Zhao, Z Q; Bai, M; Su, L P

    2016-03-23

    To study the incidence of positive t(14; 18) and myc gene rearrangement, and the clinical features and prognosis of concurrent positive t(14; 18) and myc gene rearrangement "double-hit lymphoma" (DHL) in diffuse large B cell lymphoma. The positive t(14; 18) and myc gene rearrangement in 106 cases of DLBCL were analyzed using interphase fluorescent in situ hybridization (FISH) technique. The expression of myc and bcl-2 proteins was determined by immunohistochemistry. The relationship of positive t(14; 18) and myc gene rearrangement with clinical features, pathogenesis and prognosis for the patients was analyzed. SPSS 16.0 software was used for statistical analysis. Among the 106 cases, there were 27 (25.5%) cases with positive t(14; 18) and 13 (12.3%) cases with myc gene rearrangement, and 7 cases (6.6%) of DLBCL with concurrent t(14; 18)-positive and myc gene rearrangement. A relationship was observed between positive t(14; 18) and myc gene rearrangement (P=0.019). The follow-up data showed that the 7 DHL patients were in age of 52-84 years, the International Prognostic Index (IPI) scores were 3 in two cases, 4 in four cases and 5 in one case, and the ECOG scores were 3 in all the 7 cases. Four patients had bone marrow involvement and were combined with leukemia. The survival time ranged from 0.5 to 6 months, with a median survival of 4 months. The univariate analysis showed that B symptom, Ann Arbor stage, ECOG score, LDH level, IPI score, immunophenotype, bcl-2 protein expression, myc protein expression, and myc gene rearrangement were all associated with poor prognosis (P<0.05 for all). The multivariate analysis using a COX proportional hazard model confirmed that ECOG score, bcl-2 protein expression, myc protein expression, myc gene rearrangement, and immunophenotype were independent prognostic factors affecting survival (P<0.05 for all), among them, the myc gene rearrangement was the strongest prognostic factor (OR=4.337, P<0.001). "Double-hit" DLBCL is rare

  2. C-Myc induced compensated cardiac hypertrophy increases free fatty acid utilization for the citric acid cycle.

    PubMed

    Olson, Aaron K; Ledee, Dolena; Iwamoto, Kate; Kajimoto, Masaki; O'Kelly Priddy, Colleen; Isern, Nancy; 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) injections. Isolated working hearts and (13)Carbon ((13)C)-NMR were used to measure function and fractional contributions (Fc) to the citric acid cycle by using perfusate containing (13)C-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 assessed 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 contributions in NTG. Substrate utilization was not significantly altered in 3dMyc versus Cont. The free fatty acid FC was significantly greater in 7dMyc versus 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 for the citric acid cycle 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

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

    PubMed Central

    OLSON, AARON K.; LEDEE, DOLENA; IWAMOTO, KATE; KAJIMOTO, MASAKI; PRIDDY, COLLEEN O’KELLY; ISERN, NANCY; PORTMAN, MICHAEL A.

    2012-01-01

    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) injections. 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 assessed 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 contributions in NTG. Substrate utilization was not significantly altered in 3dMyc versus Cont. The free fatty acid FC was significantly greater in 7dMyc versus 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 for the citric acid cycle 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

  4. 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

  5. Skin epidermis lacking the c-myc gene is resistant to Ras-driven tumorigenesis but can reacquire sensitivity upon additional lossof the p21Cip1 gene

    PubMed Central

    Oskarsson, Thordur; Essers, Marieke Alida Gertruda; Dubois, Nicole; Offner, Sandra; Dubey, Christelle; Roger, Catherine; Metzger, Daniel; Chambon, Pierre; Hummler, Edith; Beard, Peter; Trumpp, Andreas

    2006-01-01

    The target gene(s) required for Myc-mediated tumorigenesis are still elusive. Here we show that while endogenous c-Myc is surprisingly dispensable for skin homeostasis and TPA-induced hyperplasia, c-Myc-deficient epidermis is resistant to Ras-mediated DMBA/TPAinduced tumorigenesis. This is mechanistically linked to p21Cip1, which is induced in tumors by the activated Ras–ERK pathway but repressed by c-Myc. Acute elimination of c-Myc in established tumors leads to the up-regulation of p21Cip1, and epidermis lacking both p21Cip1 and c-Myc reacquires normal sensitivity to DMBA/TPA-induced tumorigenesis. This identifies c-Myc-mediated repression of p21Cip1 as a key step for Ras-driven epidermal tumorigenesis. PMID:16882980

  6. Ketogenic HMGCS2 Is a c-Myc target gene expressed in differentiated cells of human colonic epithelium and down-regulated in colon cancer.

    PubMed

    Camarero, Nuria; Mascaró, Cristina; Mayordomo, Cristina; Vilardell, Felip; Haro, Diego; Marrero, Pedro F

    2006-09-01

    HMGCS2, the gene that regulates ketone body production, is expressed in liver and several extrahepatic tissues, such as the colon. In CaCo-2 colonic epithelial cells, the expression of this gene increases with cell differentiation. Accordingly, immunohistochemistry with specific antibodies shows that HMGCS2 is expressed mainly in differentiated cells of human colonic epithelium. Here, we used a chromatin immunoprecipitation assay to study the molecular mechanism responsible for this expression pattern. The assay revealed that HMGCS2 is a direct target of c-Myc, which represses HMGCS2 transcriptional activity. c-Myc transrepression is mediated by blockade of the transactivating activity of Miz-1, which occurs mainly through a Sp1-binding site in the proximal promoter of the gene. Accordingly, the expression of human HMGCS2 is down-regulated in 90% of Myc-dependent colon and rectum tumors. HMGCS2 protein expression is down-regulated preferentially in moderately and poorly differentiated carcinomas. In addition, it is also down-regulated in 80% of small intestine Myc-independent tumors. Based on these findings, we propose that ketogenesis is an undesirable metabolic characteristic of the proliferating cell, which is down-regulated through c-Myc-mediated repression of the key metabolic gene HMGCS2.

  7. Differential Regulation of N-Myc and c-Myc Synthesis, Degradation, and Transcriptional Activity by the Ras/Mitogen-activated Protein Kinase Pathway*

    PubMed Central

    Kapeli, Katannya; Hurlin, Peter J.

    2011-01-01

    Myc transcription factors are important regulators of proliferation and can promote oncogenesis when deregulated. Deregulated Myc expression in cancers can result from MYC gene amplification and translocation but also from alterations in mitogenic signaling pathways that affect Myc levels through both transcriptional and post-transcription mechanisms. For example, mutations in Ras family GTPase proteins that cause their constitutive activation can increase cellular levels of c-Myc by interfering with its rapid proteasomal degradation. Although enhanced protein stability is generally thought to be applicable to other Myc family members, here we show that c-Myc and its paralog N-Myc respond to oncogenic H-Ras (H-RasG12V) in very different ways. H-RasG12V promotes accumulation of both c-Myc and N-Myc, but although c-Myc accumulation is achieved by enhanced protein stability, N-Myc accumulation is associated with an accelerated rate of translation that overcomes a surprising H-RasG12V-mediated destabilization of N-Myc. We show that H-RasG12V-mediated degradation of N-Myc functions independently of key phosphorylation sites in the highly conserved Myc homology box I region that controls c-Myc protein stability by oncogenic Ras. Finally, we found that N-Myc and c-Myc transcriptional activity is associated with their proteasomal degradation but that N-Myc may be uniquely dependent on Ras-stimulated proteolysis for target gene expression. Taken together, these studies provide mechanistic insight into how oncogenic Ras augments N-Myc levels in cells and suggest that enhanced N-Myc translation and degradation-coupled transactivation may contribute to oncogenesis. PMID:21908617

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

    PubMed

    Sadeghi, Samira; Hojati, Zohreh; Tabatabaeian, Hossein

    2017-03-01

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

  9. The Jasmonate-Activated Transcription Factor MdMYC2 Regulates ETHYLENE RESPONSE FACTOR and Ethylene Biosynthetic Genes to Promote Ethylene Biosynthesis during Apple Fruit Ripening[OPEN

    PubMed Central

    Xu, Yaxiu; Zhang, Lichao; Ji, Yinglin; Tan, Dongmei; Yuan, Hui

    2017-01-01

    The plant hormone ethylene is critical for ripening in climacteric fruits, including apple (Malus domestica). Jasmonate (JA) promotes ethylene biosynthesis in apple fruit, but the underlying molecular mechanism is unclear. Here, we found that JA-induced ethylene production in apple fruit is dependent on the expression of MdACS1, an ACC synthase gene involved in ethylene biosynthesis. The expression of MdMYC2, encoding a transcription factor involved in the JA signaling pathway, was enhanced by MeJA treatment in apple fruits, and MdMYC2 directly bound to the promoters of both MdACS1 and the ACC oxidase gene MdACO1 and enhanced their transcription. Furthermore, MdMYC2 bound to the promoter of MdERF3, encoding a transcription factor involved in the ethylene-signaling pathway, thereby activating MdACS1 transcription. We also found that MdMYC2 interacted with MdERF2, a suppressor of MdERF3 and MdACS1. This protein interaction prevented MdERF2 from interacting with MdERF3 and from binding to the MdACS1 promoter, leading to increased transcription of MdACS1. Collectively, these results indicate that JA promotes ethylene biosynthesis through the regulation of MdERFs and ethylene biosynthetic genes by MdMYC2. PMID:28550149

  10. 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

  11. An initiation site of DNA replication with transcriptional enhancer activity present upstream of the c-myc gene.

    PubMed Central

    Iguchi-Ariga, S M; Okazaki, T; Itani, T; Ogata, M; Sato, Y; Ariga, H

    1988-01-01

    We have previously reported that c-myc protein may promote cellular DNA replication by binding to initiation sites of replication. Here we report that a putative origin of human cellular DNA replication (ori) is present at approximately 2 kb upstream of the coding region of the c-myc gene itself. The c-myc protein, or protein(s) complexed with c-myc protein, bind to the upstream region (approximately 200 bp in length) which has transcriptional enhancer activity as well as autonomously replicating activity in human cells, suggesting that the c-myc protein may be an enhancer binding protein as well as a DNA replication protein. Results with deletion mutants suggest that the sequence essential to the origin of DNA replication may be adjacent to, but cannot be clearly separated from, the sequence responsible for enhancer activity. Furthermore, when cloned DNA containing putative c-myc protein binding sequences was transfected as competitor into HL-60 cells, expression of c-myc was inhibited, suggesting that c-myc protein itself may be necessary for c-myc expression. Images PMID:3053161

  12. Proximity of thyroglobulin and c-myc genes on human chromosome 8.

    PubMed

    Rabin, M; Barker, P E; Ruddle, F H; Brocas, H; Targovnik, H; Vassart, G

    1985-07-01

    The human thyroglobulin structural gene (TG) was mapped to the long arm of chromosome 8 by blot hydridization of a TG cDNA probe to DNA from 21 human X mouse somatic cell hybrids containing overlapping subsets of human chromosomes. In situ hybridization of the TG probe to metaphase chromosomes from a karyotypically normal human lymphoblastoid cell line, JS, localized the TG gene to within the region 8q23----q24.3. Thus, the TG and c-myc genes map to the same chromosome band in normal human cells. In a human colon carcinoma cell line (COLO 320 DM) which contains amplified c-myc, the TG gene is not amplified and hence it lies outside the amplification domain.

  13. Multi-focal control of mitochondrial gene expression by oncogenic MYC provides potential therapeutic targets in cancer

    PubMed Central

    Oran, Amanda R.; Adams, Clare M.; Zhang, Xiao-yong; Gennaro, Victoria J.; Pfeiffer, Harla K.; Mellert, Hestia S.; Seidel, Hans E.; Mascioli, Kirsten; Kaplan, Jordan; Gaballa, Mahmoud R.; Shen, Chen; Rigoutsos, Isidore; King, Michael P.; Cotney, Justin L.; Arnold, Jamie J.; Sharma, Suresh D.; Martinez, Ubaldo E.; Vakoc, Christopher R.; Chodosh, Lewis A.; Thompson, James E.; Bradner, James E.; Cameron, Craig E.; Shadel, Gerald S.; Eischen, Christine M.; McMahon, Steven B.

    2016-01-01

    Despite ubiquitous activation in human cancer, essential downstream effector pathways of the MYC transcription factor have been difficult to define and target. Using a structure/function-based approach, we identified the mitochondrial RNA polymerase (POLRMT) locus as a critical downstream target of MYC. The multifunctional POLRMT enzyme controls mitochondrial gene expression, a process required both for mitochondrial function and mitochondrial biogenesis. We further demonstrate that inhibition of this newly defined MYC effector pathway causes robust and selective tumor cell apoptosis, via an acute, checkpoint-like mechanism linked to aberrant electron transport chain complex assembly and mitochondrial reactive oxygen species (ROS) production. Fortuitously, MYC-dependent tumor cell death can be induced by inhibiting the mitochondrial gene expression pathway using a variety of strategies, including treatment with FDA-approved antibiotics. In vivo studies using a mouse model of Burkitt's Lymphoma provide pre-clinical evidence that these antibiotics can successfully block progression of MYC-dependent tumors. PMID:27590350

  14. 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

  15. Role of calcium in prolactin-stimulated c-myc gene expression and mitogenesis in Nb2 lymphoma cells

    SciTech Connect

    Murphy, P.R.; DiMattia, G.E.; Friesen, H.G.

    1988-06-01

    Receptor-activated transmembrane calcium flux has been implicated as a mediator of the actions of many growth factors and hormones. We examined the effects of PRL, calcium ionophores, and calcium antagonists on /sup 45/Ca2+ flux, c-myc gene expression, and DNA synthesis in the PRL-dependent rat Nb2 lymphoma cell line. PRL had no detectable effects on /sup 45/Ca2+ uptake or efflux, and the mitogenic effects of PRL could not be reproduced by the calcium ionophore A23187 alone or in combination with the tumor-promoting phorbol ester 12-O-tetra-decanoyl-phorbol-13 acetate (TPA). PRL, but not A23187 or TPA, stimulated c-myc gene expression in quiescent Nb2 cells. Exposure to PRL for brief periods (15 min to 4 h), followed by extensive washing, resulted in a time- and dose-dependent activation of DNA synthesis measured 16 h later. This activation was not blocked by addition of excess anti-PRL antiserum after the wash steps, indicating that the observed stimulation was not due to residual PRL. Despite the marked increase in DNA synthesis, removal of PRL after 4 h prevented mitosis, suggesting that PRL may be required throughout the cell cycle for Nb2 cell proliferation. Although continuous incubation with calcium antagonists resulted in a dose-dependent inhibition of PRL-stimulated DNA synthesis, activation of DNA synthesis by brief exposure to PRL was not inhibited by the presence of EGTA, calcium channel blockers (nifedipine, cobalt chloride), or calmodulin inhibitors (trifluoperazine, N-6-aminohexyl-5-chloronaphthalene sulfonamide). PRL-stimulated c-myc expression was attenuated, but not blocked, by the calcium channel antagonists. However, the putative intracellular calcium antagonist TMB-8 inhibited both c-myc expression and DNA synthesis in a dose-dependent manner (IC50 = 16 microM).

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

    PubMed

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

    2012-02-01

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

  17. Transduction of Oct6 or Oct9 gene concomitant with Myc family gene induced osteoblast-like phenotypic conversion in normal human fibroblasts

    SciTech Connect

    Mizoshiri, N.; Kishida, T.; Yamamoto, K.; Shirai, T.; Terauchi, R.; Tsuchida, S.; Mori, Y.; Ejima, A.; Sato, Y.; Arai, Y.; Fujiwara, H.; Yamamoto, T.; Kanamura, N.; Mazda, O.; Kubo, T.

    2015-11-27

    Introduction: Osteoblasts play essential roles in bone formation and regeneration, while they have low proliferation potential. Recently we established a procedure to directly convert human fibroblasts into osteoblasts (dOBs). Transduction of Runx2 (R), Osterix (X), Oct3/4 (O) and L-myc (L) genes followed by culturing under osteogenic conditions induced normal human fibroblasts to express osteoblast-specific genes and produce calcified bone matrix both in vitro and in vivo Intriguingly, a combination of only two factors, Oct3/4 and L-myc, significantly induced osteoblast-like phenotype in fibroblasts, but the mechanisms underlying the direct conversion remains to be unveiled. Materials and Methods: We examined which Oct family genes and Myc family genes are capable of inducing osteoblast-like phenotypic conversion. Results: As result Oct3/4, Oct6 and Oct9, among other Oct family members, had the capability, while N-myc was the most effective Myc family gene. The Oct9 plus N-myc was the best combination to induce direct conversion of human fibroblasts into osteoblast-like cells. Discussion: The present findings may greatly contribute to the elucidation of the roles of the Oct and Myc proteins in osteoblast direct reprogramming. The results may also lead to establishment of novel regenerative therapy for various bone resorption diseases. - Highlights: • Introducing L-myc in a combination with either Oct3/4, Oct6 or Oct9 enables the conversion of fibroblasts to osteoblasts. • A combination of L-myc with Oct3/4 or Oct9 can induce the cells to a phenotype closer to normal osteoblasts. • N-myc was considered the most appropriate Myc family gene for induction of osteoblast-like phenotype in fibroblasts. • The combination of Oct9 plus N-myc has the strongest capability of inducing osteoblast-like phenotype.

  18. Cell transformation by the v-myc oncogene abrogates c-Myc/Max-mediated suppression of a C/EBP beta-dependent lipocalin gene.

    PubMed

    Hartl, Markus; Matt, Theresia; Schüler, Wolfgang; Siemeister, Gerd; Kontaxis, Georg; Kloiber, Karin; Konrat, Robert; Bister, Klaus

    2003-10-10

    Using differential hybridization techniques, a cDNA clone (Q83) was isolated that corresponds to a highly abundant mRNA in quail embryo fibroblasts transformed by the v-myc oncogene. The deduced 178 amino acid protein product of Q83 contains an N-terminal signal sequence and a lipocalin sequence motif, the hallmark of a family of secretory proteins binding and transporting small hydrophobic molecules of diverse biological function, including retinoids and steroids. The quail Q83 protein displays 87% sequence identity with a developmentally regulated chicken protein, termed p20K or Ch21. Cell transformation specifically by v-myc, but not by other oncogenic agents, induces high-level expression of Q83 mRNA and of the Q83 protein. Nucleotide sequence analysis and transcriptional mapping revealed that the Q83 gene encompasses seven exons with the coding region confined to exons 1 through 6. The promoter region contains consensus binding sites for the transcriptional regulators Myc and C/EBP beta. Transcriptional activation of Q83 is principally dependent on C/EBP beta, but is blocked in normal cells by the endogenous c-Myc/Max/Mad transcription factor network. In v-myc-transformed cells, high-level expression of the v-Myc protein and formation of highly stable v-Myc/Max heterodimers leads to abrogation of Q83 gene suppression and activation by C/EBP beta. A 157 amino acid residue recombinant protein representing the secreted form of Q83 was used for structure determination by nuclear magnetic resonance spectroscopy. Q83 folds into a single globular domain of the lipocalin-type. The central part consists of an eight-stranded up-and-down beta-barrel core flanked by an N-terminal 3(10)-like helix and a C-terminal alpha-helix. The orientation of the C-terminal alpha-helix is partially determined by a disulfide bridge between Cys59 and Cys152. The three-dimensional structure determination of the Q83 protein will facilitate the identification of its authentic ligand and the

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

    PubMed Central

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

    2012-01-01

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

  20. MYC-induced apoptosis in mammary epithelial cells is associated with repression of lineage-specific gene signatures

    PubMed Central

    Haikala, Heidi M.; Klefström, Juha; Eilers, Martin; Wiese, Katrin E.

    2016-01-01

    ABSTRACT Apoptosis caused by deregulated MYC expression is a prototype example of intrinsic tumor suppression. However, it is still unclear how supraphysiological MYC expression levels engage specific sets of target genes to promote apoptosis. Recently, we demonstrated that repression of SRF target genes by MYC/MIZ1 complexes limits AKT-dependent survival signaling and contributes to apoptosis induction. Here we report that supraphysiological levels of MYC repress gene sets that include markers of basal-like breast cancer cells, but not luminal cancer cells, in a MIZ1-dependent manner. Furthermore, repressed genes are part of a conserved gene signature characterizing the basal subpopulation of both murine and human mammary gland. These repressed genes play a role in epithelium and mammary gland development and overlap with genes mediating cell adhesion and extracellular matrix organization. Strikingly, acute activation of oncogenic MYC in basal mammary epithelial cells is sufficient to induce luminal cell identity markers. We propose that supraphysiological MYC expression impacts on mammary epithelial cell identity by repressing lineage-specific target genes. Such abrupt cell identity switch could interfere with adhesion-dependent survival signaling and thus promote apoptosis in pre-malignant epithelial tissue. PMID:26873145

  1. Sexual Dimorphism of Body Size Is Controlled by Dosage of the X-Chromosomal Gene Myc and by the Sex-Determining Gene tra in Drosophila.

    PubMed

    Mathews, Kristina Wehr; Cavegn, Margrith; Zwicky, Monica

    2017-03-01

    Drosophila females are larger than males. In this article, we describe how X-chromosome dosage drives sexual dimorphism of body size through two means: first, through unbalanced expression of a key X-linked growth-regulating gene, and second, through female-specific activation of the sex-determination pathway. X-chromosome dosage determines phenotypic sex by regulating the genes of the sex-determining pathway. In the presence of two sets of X-chromosome signal elements (XSEs), Sex-lethal (Sxl) is activated in female (XX) but not male (XY) animals. Sxl activates transformer (tra), a gene that encodes a splicing factor essential for female-specific development. It has previously been shown that null mutations in the tra gene result in only a partial reduction of body size of XX animals, which shows that other factors must contribute to size determination. We tested whether X dosage directly affects animal size by analyzing males with duplications of X-chromosomal segments. Upon tiling across the X chromosome, we found four duplications that increase male size by >9%. Within these, we identified several genes that promote growth as a result of duplication. Only one of these, Myc, was found not to be dosage compensated. Together, our results indicate that both Myc dosage and tra expression play crucial roles in determining sex-specific size in Drosophila larvae and adult tissue. Since Myc also acts as an XSE that contributes to tra activation in early development, a double dose of Myc in females serves at least twice in development to promote sexual size dimorphism. Copyright © 2017 by the Genetics Society of America.

  2. Sexual Dimorphism of Body Size Is Controlled by Dosage of the X-Chromosomal Gene Myc and by the Sex-Determining Gene tra in Drosophila

    PubMed Central

    Mathews, Kristina Wehr; Cavegn, Margrith; Zwicky, Monica

    2017-01-01

    Drosophila females are larger than males. In this article, we describe how X-chromosome dosage drives sexual dimorphism of body size through two means: first, through unbalanced expression of a key X-linked growth-regulating gene, and second, through female-specific activation of the sex-determination pathway. X-chromosome dosage determines phenotypic sex by regulating the genes of the sex-determining pathway. In the presence of two sets of X-chromosome signal elements (XSEs), Sex-lethal (Sxl) is activated in female (XX) but not male (XY) animals. Sxl activates transformer (tra), a gene that encodes a splicing factor essential for female-specific development. It has previously been shown that null mutations in the tra gene result in only a partial reduction of body size of XX animals, which shows that other factors must contribute to size determination. We tested whether X dosage directly affects animal size by analyzing males with duplications of X-chromosomal segments. Upon tiling across the X chromosome, we found four duplications that increase male size by >9%. Within these, we identified several genes that promote growth as a result of duplication. Only one of these, Myc, was found not to be dosage compensated. Together, our results indicate that both Myc dosage and tra expression play crucial roles in determining sex-specific size in Drosophila larvae and adult tissue. Since Myc also acts as an XSE that contributes to tra activation in early development, a double dose of Myc in females serves at least twice in development to promote sexual size dimorphism. PMID:28064166

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

    PubMed

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

    2015-02-21

    To identify the genes induced and regulated by the MYC protein in generating tumors from liver stem cells. 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. 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. 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.

  4. Changes in the gene expression of C-myc and CD38 in HL-60 cells during differentiation induced by nicotinic acid-related compounds.

    PubMed

    Ida, Chieri; Ogata, Shin; Okumura, Katsuzumi; Taguchi, Hiroshi

    2008-03-01

    Changes in gene expression levels of c-myc and CD38 were examined during the differentiation of HL-60 cells to granulocytes due to three nicotinic acid-related compounds. CD38 expression was increased by isonicotinic acid and all-trans-retinoic acid (ATRA). Nicotinamide and nicotinamide N-oxide drastically decreased c-myc expression, but isonicotinic acid had no effect, suggesting that these compounds differentiate HL-60 to granulocytes through different pathways. These results should provide useful information as to the mechanisms of cell differentiation.

  5. 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.

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

    PubMed

    Futami, Kunihiko; Zhang, Huan; Okamoto, Nobuaki

    2005-12-19

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

  7. Potential role of the N-MYC downstream-regulated gene family in reprogramming cancer metabolism under hypoxia

    PubMed Central

    Lee, Ga Young; Chun, Yang-Sook; Shin, Hyun-Woo; Park, Jong-Wan

    2016-01-01

    Metabolic reprogramming toward aerobic glycolysis and lactate fermentation supplies cancer cells with intermediate metabolites, which are used as macromolecule precursors. The oncogene MYC contributes to such aerobic metabolism by activating the expression of numerous genes essential for glycolysis and mitochondrial biogenesis. However, to survive and evolve in a hypoxic tumor milieu, cancer cells must revise MYC-driven metabolism because the mitochondrial respiratory chain provides free electrons to generate oxygen free radicals with inefficient production of ATP due to oxygen depletion. Instead, hypoxia-inducible transcription factor hypoxia-inducible factor 1 (HIF-1) takes over the role of MYC in glycolysis, but suppresses mitochondrial biogenesis and activity to protect cells from such threats. Recently, the N-MYC downstream-regulated gene (NDRG) family has received attention as potential biomarkers of cancer prognosis. NDRGs are repressed MYC-dependently in various cancers, but induced under hypoxia because HIF-1 directly activates their promoters and indirectly de-represses them by antagonizing MYC. In this review, we summarize the current understanding of the reprogramming of cancer metabolism via the counterbalance between MYC and HIF-1, and discuss the proven and putative roles of the NDRG family in adjusting cancer metabolism according to the ambient oxygen level. PMID:27447861

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

    PubMed

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

    2015-01-13

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

  9. C-MYC Transcriptionally Amplifies SOX2 Target Genes to Regulate Self-Renewal in Multipotent Otic Progenitor Cells

    PubMed Central

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

    2014-01-01

    Summary Sensorineural hearing loss is caused by the loss of sensory hair cells and neurons of the inner ear. Once lost, these cell types are not replaced. Two genes expressed in the developing inner ear are c-Myc and Sox2. We created immortalized multipotent otic progenitor (iMOP) cells, a fate-restricted cell type, by transient expression of C-MYC in SOX2-expressing otic progenitor cells. This activated the endogenous C-MYC and amplified existing SOX2-dependent transcripts to promote self-renewal. RNA-seq and ChIP-seq analyses revealed that C-MYC and SOX2 occupy over 85% of the same promoters. C-MYC and SOX2 target genes include cyclin-dependent kinases that regulate cell-cycle progression. iMOP cells continually divide but retain the ability to differentiate into functional hair cells and neurons. We propose that SOX2 and C-MYC regulate cell-cycle progression of these cells and that downregulation of C-MYC expression after growth factor withdrawal serves as a molecular switch for differentiation. PMID:25497456

  10. Increased mRNA Levels of TCF7L2 and MYC of the Wnt Pathway in Tg-ArcSwe Mice and Alzheimer's Disease Brain

    PubMed Central

    Blom, Elin S.; Wang, Yijing; Skoglund, Lena; Hansson, Anita C.; Ubaldi, Massimo; Lourdusamy, Anbarasu; Sommer, Wolfgang H.; Mielke, Matthew; Hyman, Bradley T.; Heilig, Markus; Lannfelt, Lars; Nilsson, Lars N. G.; Ingelsson, Martin

    2011-01-01

    Several components in the Wnt pathway, including β-catenin and glycogen synthase kinase 3 beta, have been implied in AD pathogenesis. Here, mRNA brain levels from five-month-old tg-ArcSwe and nontransgenic mice were compared using Affymetrix microarray analysis. With surprisingly small overall changes, Wnt signaling was the most affected pathway with altered expression of nine genes in tg-ArcSwe mice. When analyzing mRNA levels of these genes in human brain, transcription factor 7-like 2 (TCF7L2) and v-myc myelocytomatosis viral oncogene homolog (MYC), were increased in Alzheimer's disease (AD) (P < .05). Furthermore, no clear differences in TCF7L2 and MYC mRNA were found in brains with frontotemporal lobar degeneration, suggesting that altered regulation of these Wnt-related genes could be specific to AD. Finally, mRNA levels of three neurogenesis markers were analyzed. Increased mRNA levels of dihydropyrimidinase-like 3 were observed in AD brain, suggesting that altered Wnt pathway regulation may signify synaptic rearrangement or neurogenesis. PMID:21234373

  11. Promiscuous Rearrangements of the MYC Locus Hijack Enhancers and Super-Enhancers to Dysregulate MYC Expression in Multiple Myeloma

    PubMed Central

    Affer, Maurizio; Chesi, Marta; Chen, Wei-Dong G.; Keats, Jonathan J.; Demchenko, Yulia N.; Roschke, Anna V.; Van Wier, Scott; Fonseca, Rafael

    2014-01-01

    MYC locus rearrangements – often complex combinations of translocations, insertions, deletions, and inversions - in multiple myeloma (MM) were thought to be a late progression event, which often did not involve immunoglobulin genes. Yet germinal center activation of MYC expression has been reported to cause progression to MM in an MGUS prone mouse strain. Although previously detected in 16% of MM, we find MYC rearrangements in nearly 50% of MM, including smoldering MM, and they are heterogeneous in some cases. Rearrangements reposition MYC near a limited number of genes associated with conventional enhancers, but mostly with super-enhancers (e.g., IGH, IGL, IGK, NSMCE2, TXNDC5, FAM46C, FOXO3, IGJ, PRDM1). MYC rearrangements are associated with a significant increase of MYC expression that is monoallelic, but MM tumors lacking a rearrangement have bi-allelic MYC expression at significantly higher levels than in MGUS. We also show that germinal center activation of MYC does not cause MM in a mouse strain that rarely develops spontaneous MGUS. It appears that increased MYC expression at the MGUS/MM transition usually is bi-allelic, but sometimes can be mono-allelic if there is a MYC rearrangement. Our data suggests that MYC rearrangements, regardless of when they occur during MM pathogenesis, provide one event that contributes to tumor autonomy. PMID:24518206

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

    PubMed

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

    2017-04-01

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

  13. Repression of the c-fms gene in fibroblast cells by c-Myc-MM-1-TIF1beta complex.

    PubMed

    Satou, Akiko; Hagio, Yuko; Taira, Takahiro; Iguchi-Ariga, Sanae M M; Ariga, Hiroyoshi

    2004-08-13

    MM-1 has been reported to repress the E-box-dependent transcription activity of c-Myc by recruiting histone deacetylase 1 complex via TIF1beta/KAP1. In this study, to identify target genes for c-Myc-MM-1-TIF1beta, we established rat-1 cells harboring the dominant-negative form of TIF1beta to abrogate the pathway from TIF1beta to MM-1-c-Myc. This cell line, in which transcription activity of c-Myc was activated, was found to be tumorigenic. By DNA-microarray analysis of this cell line, expression and promoter activity of the c-fms oncogene were found to be upregulated. Of the two promoters, pE1 and pE2, in the c-fms gene, pE1 promoter activity was found to be activated in an E-box-dependent manner.

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

    PubMed Central

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

    2016-01-01

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

  15. 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. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

  16. c-myc Regulates Cell Proliferation during Lens Development

    PubMed Central

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

    2014-01-01

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

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

    PubMed

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

    2014-09-01

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

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

    PubMed

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

    2014-03-01

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

  19. Targeting c-Myc-activated genes with a correlation method: Detection of global changes in large gene expression network dynamics

    PubMed Central

    Remondini, D.; O'Connell, B.; Intrator, N.; Sedivy, J. M.; Neretti, N.; Castellani, G. C.; Cooper, L. N.

    2005-01-01

    This work studies the dynamics of a gene expression time series network. The network, which is obtained from the correlation of gene expressions, exhibits global dynamic properties that emerge after a cell state perturbation. The main features of this network appear to be more robust when compared with those obtained with a network obtained from a linear Markov model. In particular, the network properties strongly depend on the exact time sequence relationships between genes and are destroyed by random temporal data shuffling. We discuss in detail the problem of finding targets of the c-myc protooncogene, which encodes a transcriptional regulator whose inappropriate expression has been correlated with a wide array of malignancies. The data used for network construction are a time series of gene expression, collected by microarray analysis of a rat fibroblast cell line expressing a conditional Myc-estrogen receptor oncoprotein. We show that the correlation-based model can establish a clear relationship between network structure and the cascade of c-myc-activated genes. PMID:15867157

  20. 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. Copyright © 2014 Elsevier B.V. All rights reserved.

  1. Smyd2 is a Myc-regulated gene critical for MLL-AF9 induced leukemogenesis

    PubMed Central

    Bagislar, Sevgi; Sabò, Arianna; Kress, Theresia R.; Doni, Mirko; Nicoli, Paola; Campaner, Stefano; Amati, Bruno

    2016-01-01

    The Smyd2 protein (Set- and Mynd domain containing protein 2) is a methyl-transferase that can modify both histones and cytoplasmic proteins. Smyd2 is over-expressed in several cancer types and was shown to be limiting for tumor development in the pancreas. However, genetic evidence for a role of Smyd2 in other cancers or in mouse development was missing to date. Using germ line-deleted mouse strains, we now show that Smyd2 and the related protein Smyd3 are dispensable for normal development. Ablation of Smyd2 did not affect hematopoiesis, but retarded the development of leukemia promoted by MLL-AF9, a fusion oncogene associated with acute myeloid leukemia (AML) in humans. Smyd2-deleted leukemic cells showed a competitive disadvantage relative to wild-type cells, either in vitro or in vivo. The Smyd2 gene was directly activated by the oncogenic transcription factor Myc in either MLL9-AF9-induced leukemias, Myc-induced lymphomas, or fibroblasts. However, unlike leukemias, the development of lymphomas was not dependent upon Smyd2. Our data indicate that Smyd2 has a critical role downstream of Myc in AML. PMID:27655694

  2. MYC translocation and an increased copy number predict poor prognosis in adult diffuse large B-cell lymphoma (DLBCL), especially in germinal centre-like B cell (GCB) type.

    PubMed

    Yoon, S O; Jeon, Y K; Paik, J H; Kim, W Y; Kim, Y A; Kim, J E; Kim, C W

    2008-08-01

    Diffuse large B-cell lymphoma (DLBCL) is a heterogeneous disease with various genetic alterations. The aim was to investigate MYC, Bcl-2 and Bcl-6 translocations and copy number changes in adult DLBCLs to evaluate their clinicopathological features and prognostic implications. Gene status was examined using fluorescence in situ hybridization (FISH), and the results were analysed in the context of germinal centre B-cell (GCB) and non-GCB type of DLBCL based on immunohistochemistry. MYC translocation was observed in 9% (14 of 156), and an increased copy number (ICN) in 7.1% (11 of 156). MYC translocation was more common in GCB type (22%) than in non-GCB type (4.9%), and associated with advanced International Prognostic Index (IPI). MYC aberration, i.e. translocation or increased copy number (ICN), was significantly associated with shorter overall survival, especially for the GCB type. Bcl-2 translocation was rare (3.4%, five of 145), and ICN was observed in 11.7% (17 of 145), more frequently in non-GCB type (16%) than in GCB type (2.5%). Bcl-2 aberration tended to have an adverse effect on survival. In multivariate analysis, MYC ICN was an independent poor prognostic factor. Analyses of MYC and Bcl-2 status, i.e. translocation and ICN, in the context of DLBCL phenotype might help predict prognosis and determine therapeutic strategies.

  3. 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.

  4. Do products of the myc proto-oncogene play a role in transcriptional regulation of the prothymosin alpha gene?

    PubMed Central

    Mol, P C; Wang, R H; Batey, D W; Lee, L A; Dang, C V; Berger, S L

    1995-01-01

    The Myc protein has been reported to activate transcription of the rat prothymosin alpha gene by binding to an enhancer element or E box (CACGTG) located in the first intron (S. Gaubatz et al., Mol. Cell. Biol. 14:3853-3862, 1994). The human prothymosin alpha gene contains two such motifs: in the promoter region at kb -1.2 and in intron 1, approximately 2 kb downstream of the transcriptional start site in a region which otherwise bears little homology to the rat gene. Using chloramphenicol acetyltransferase (CAT) reporter constructs driven either by the 5-kb human prothymosin alpha promoter or by a series of truncated promoters, we showed that removal of the E-box sequence had no effect on transient expression of CAT activity in mouse L cells. When intron 1 of the prothymosin alpha gene was inserted into the most extensive promoter construct downstream of the CAT coding region, a diminution in transcription, which remained virtually unchanged upon disruption of the E boxes, was observed. CAT constructs driven by the native prothymosin alpha promoter or the native promoter and intron were indifferent to Myc; equivalent CAT activity was observed in the presence of ectopic normal or mutant Myc genes. Similarly, expression of a transiently transfected wild-type prothymosin alpha gene as the reporter was not affected by a repertoire of myc-derived genes, including myc itself and dominant or recessive negative myc mutants. In COS-1 cells, equivalent amounts of the protein were produced from transfected prothymosin alpha genes regardless of whether genomic E boxes were disrupted, intron 1 was removed, or a repertoire of myc-derived genes was included in the transfection cocktail. More importantly, cotransfection of a dominant negative Max gene failed to reduce transcription of the endogenous prothymosin alpha gene in COS cells or the wild-type transfected gene in COS or L cells. Taken together, the data do not support the idea that Myc activates transcription of the

  5. 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

  6. Gain of MYC underlies recurrent trisomy of the MYC chromosome in acute promyelocytic leukemia

    PubMed Central

    Jones, Letetia; Wei, Guangwei; Sevcikova, Sabina; Phan, Vernon; Jain, Sachi; Shieh, Angell; Wong, Jasmine C. Y.; Li, Min; Dubansky, Joshua; Maunakea, Mei Lin; Ochoa, Rachel; Zhu, George; Tennant, Thelma R.; Shannon, Kevin M.; Lowe, Scott W.; Le Beau, Michelle M.

    2010-01-01

    Gain of chromosome 8 is the most common chromosomal gain in human acute myeloid leukemia (AML). It has been hypothesized that gain of the MYC protooncogene is of central importance in trisomy 8, but the experimental data to support this are limited and controversial. In a mouse model of promyelocytic leukemia in which the MRP8 promoter drives expression of the PML-RARA fusion gene in myeloid cells, a Myc allele is gained in approximately two-thirds of cases as a result of trisomy for mouse chromosome 15. We used this model to test the idea that MYC underlies acquisition of trisomy in AML. We used a retroviral vector to drive expression of wild-type, hypermorphic, or hypomorphic MYC in bone marrow that expressed the PML-RARA transgene. MYC retroviruses cooperated in myeloid leukemogenesis and suppressed gain of chromosome 15. When the PML-RARA transgene was expressed in a Myc haploinsufficient background, we observed selection for increased copies of the wild-type Myc allele concomitant with leukemic transformation. In addition, we found that human myeloid leukemias with trisomy 8 have increased MYC. These data show that gain of MYC can contribute to the pathogenic effect of the most common trisomy of human AML. PMID:21059853

  7. Surface IgM mediated regulation of RAG gene expression in E mu-N-myc B cell lines.

    PubMed Central

    Ma, A; Fisher, P; Dildrop, R; Oltz, E; Rathbun, G; Achacoso, P; Stall, A; Alt, F W

    1992-01-01

    Transgenic mice carrying either the c-myc or N-myc oncogene deregulated by the immunoglobulin heavy chain enhancer element (E mu) develop both pre-B and B cell lymphomas (E mu-c-myc and E mu-N-myc lymphomas). We report here that B cell lines derived from these tumors, as well as a line derived from v-myc retroviral transformation, simultaneously express surface immunoglobulin (a hallmark of mature B cells) as well as a common subset of genes normally restricted to the pre-B stage of development-including the recombinase activating genes RAG-1 and RAG-2. Continued RAG-1 and RAG-2 expression in these lines is associated with VDJ recombinase activity detected with a VDJ recombination substrate. Cross-linking of the surface immunoglobulin on these lines with an anti-mu antibody leads to rapid, specific and reversible down-regulation of RAG-1 and RAG-2 gene expression. We also find that a small but significant percentage of normal surface immunoglobulin bearing bone marrow B cells express the RAG-1 gene. These findings are discussed in the context of their possible implications for the control of specific gene expression during the pre-B to B cell transition. Images PMID:1628630

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

    PubMed

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

    2013-05-01

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

  9. Myc Function in Drosophila

    PubMed Central

    Gallant, Peter

    2013-01-01

    Drosophila contains a single MYC gene. Like its vertebrate homologs, it encodes a transcription factor that activates many targets, including prominently genes involved in ribosome biogenesis and translation. This activity makes Myc a central regulator of growth and/or proliferation of many cell types, such as imaginal disc cells, polyploid cells, stem cells, and blood cells. Importantly, not only does Myc act cell autonomously but it also affects the fate of adjacent cells and tissues. This potential of Myc is harnessed by many different signaling pathways, involving, among others, Wg, Dpp, Hpo, ecdysone, insulin, and mTOR. PMID:24086064

  10. Double-hit mantle cell lymphoma with MYC gene rearrangement or amplification: a report of four cases and review of the literature

    PubMed Central

    Setoodeh, Reza; Schwartz, Stuart; Papenhausen, Peter; Zhang, Ling; Sagatys, Elizabeth M; Moscinski, Lynn C; Shao, Haipeng

    2013-01-01

    Mature B-cell lymphomas with both BCL2 and MYC translocations are known as “double hit” lymphomas. These lymphomas are aggressive and show high proliferation rate due to the growth advantages provided by MYC and BCL2 translocation and overexpression. Mantle cell lymphoma (MCL) is a neoplasm of mature B-lymphocytes with characteristic t(11;14) and subsequent Cyclin D1 overexpression. Secondary cytogenetic changes are frequent in MCL, but MYC translocation has only been rarely reported. In this study, we report four cases of MCL with MYC translocation or MYC gene amplification detected by conventional cytogenetics, fluorescence in situ hybridization and whole genome single nucleotide polymorphism (SNP) array, and determined the clinicopathologic features. Our study provides further evidence supporting the concept of “double hit” MCL with co-involvement of MYC gene rearrangement and/or amplification and CCND1 gene rearrangement. PMID:23330001

  11. A study of myc-related gene expression in small cell lung cancer by in situ hybridization.

    PubMed Central

    Gu, J.; Linnoila, R. I.; Seibel, N. L.; Gazdar, A. F.; Minna, J. D.; Brooks, B. J.; Hollis, G. F.; Kirsch, I. R.

    1988-01-01

    The expression of myc-related genes (c-myc, N-myc, and L-myc) in small cell lung cancer (SCLC) was studied by RNA-RNA tissue in situ hybridization. The tissues investigated included cytospins of ten cell lines derived from patients with SCLC, four corresponding nude mouse xenografts from cell lines, and metastatic tumor tissue obtained by surgical biopsy and at autopsy. The probes were prepared as 35S labeled complementary RNA. The expression of each gene was demonstrated specifically by autoradiography in the cytoplasm of the neoplastic cell samples. The average levels of oncogene expression in each specimen corroborated previous data obtained by Northern blot assays. In addition, heterogeneity in gene expression from cell to cell in each sample was noted. This study represents the first attempt to demonstrate oncogene expression in lung cancer cell lines and tissues in situ, and confirms that the expression of these myc related genes can be seen in the primary tumor. The technique of RNA-RNA tissue in situ hybridization has great potential in answering fundamental questions of tumor cell heterogeneity and progression in SCLC. It should be useful in both prospective and retrospective studies. Images Figure 1 Figure 2 Figure 3 Figure 4 PMID:2456019

  12. BRCA1 and c-Myc associate to transcriptionally repress psoriasin, a DNA damage-inducible gene.

    PubMed

    Kennedy, Richard D; Gorski, Julia J; Quinn, Jennifer E; Stewart, Gail E; James, Colin R; Moore, Stephen; Mulligan, Karl; Emberley, Ethan D; Lioe, Tong F; Morrison, Patrick J; Mullan, Paul B; Reid, George; Johnston, Patrick G; Watson, Peter H; Harkin, D Paul

    2005-11-15

    Evidence is accumulating to suggest that some of the diverse functions associated with BRCA1 may relate to its ability to transcriptionally regulate key downstream target genes. Here, we identify S100A7 (psoriasin), S100A8, and S100A9, members of the S100A family of calcium-binding proteins, as novel BRCA1-repressed targets. We show that functional BRCA1 is required for repression of these family members and that a BRCA1 disease-associated mutation abrogates BRCA1-mediated repression of psoriasin. Furthermore, we show that BRCA1 and c-Myc form a complex on the psoriasin promoter and that BRCA1-mediated repression of psoriasin is dependent on functional c-Myc. Finally, we show that psoriasin expression is induced by the topoisomerase IIalpha poison, etoposide, in the absence of functional BRCA1 and increased psoriasin expression enhances cellular sensitivity to this chemotherapeutic agent. Therefore, we identified a novel transcriptional mechanism that is likely to contribute to BRCA1-mediated resistance to etoposide.

  13. [Diffuse large B-cell lymphoma with concomitant c-MYC and BCL6 gene rearrangements with primary skin involvement: A case report and a review of literature].

    PubMed

    Gabeeva, N G; Koroleva, D A; Belyaeva, A V; Chernova, N G; Kuzmina, L A; Sudarikov, A B; Obukhova, T N; Kovrigina, A M; Zvonkov, E E; Savchenko, V G

    2017-01-01

    Double-hit lymphoma (DHL) is a rare aggressive B-cell lymphoma with concomitant c-MYC, BCL2 or BCL6 gene rearrangements, which is characterized by the high frequency of extranodal lesions and by resistance to chemotherapy. The median survival does not exceed 18 months in patients with this disease. The majority of DHL is represented by с-MYC/BCL2 cases. The combination of c-MYC/BCL6 occurs rarely (5-8%). The paper describes a case of DHL with concomitant c-MYC and BCL6 gene rearrangements, which mimics diffuse large B-cell lymphoma, leg-type.

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

    PubMed Central

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

    2016-01-01

    The dependence of cancer on overexpressed c-MYC and its predisposition for polyploidy represents a double puzzle. We address this conundrum by cross-species transcription analysis of c-MYC interacting genes in polyploid vs. diploid tissues and cells, including human vs. mouse heart, mouse vs. human liver and purified 4n vs. 2n mouse decidua cells. Gene-by-gene transcriptome comparison and principal component analysis indicated that c-MYC interactants are significantly overrepresented among ploidy-associated genes. Protein interaction networks and gene module analysis revealed that the most upregulated genes relate to growth, stress response, proliferation, stemness and unicellularity, as well as to the pathways of cancer supported by MAPK and RAS coordinated pathways. A surprising feature was the up-regulation of epithelial-mesenchymal transition (EMT) modules embodied by the N-cadherin pathway and EMT regulators from SNAIL and TWIST families. Metabolic pathway analysis also revealed the EMT-linked features, such as global proteome remodeling, oxidative stress, DNA repair and Warburg-like energy metabolism. Genes associated with apoptosis, immunity, energy demand and tumour suppression were mostly down-regulated. Noteworthy, despite the association between polyploidy and ample features of cancer, polyploidy does not trigger it. Possibly it occurs because normal polyploidy does not go that far in embryonalisation and linked genome destabilisation. In general, the analysis of polyploid transcriptome explained the evolutionary relation of c-MYC and polyploidy to cancer. PMID:27655693

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

    PubMed

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

    2016-11-15

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

  16. Immortalization by c-myc, H-ras, and Ela oncogenes induces differential cellular gene expression and growth factor responses

    SciTech Connect

    Kelekar, A.; Cole, M.D.

    1987-11-01

    Early-passage rat kidney cells were immortalized or rescued from senescence with three different oncogenes: viral promoter-driven c-myc, H-ras (Val-12), and adenovirus type 5 E1a. The normal c-myc and H-ras (Gly-12) were unable to immortalize cells under similar conditions. Quantitation of RNA in the ras-immortalized lines demonstrated that the H-ras oncogene was expressed at a level equivalent to that of the normal H-ras gene in established human or rat cell lines. Cell lines immortalized by different oncogenes were found to have distinct growth responses to individual growth factors in a short-term assay. E1a-immortalized cells were largely independent of serum growth factors, whereas c-myc-immortalized cells responded to serum better than to epidermal growth factor and insulin. H-ras-immortalized cells responded significantly to insulin alone and gave a maximal response to epidermal growth factor and insulin. Several cellular genes associated with platelet-derived growth factor stimulation, including c-myc, were expressed at high levels in the H-ras-immortalized cells, and c-myc expression was deregulated, suggesting that the H-ras oncogene has provided a ''competence'' function. H-ras-immortalized cells could not be morphologically transformed by secondary transfection with a long terminal repeat-c-myc oncogene, but secondary transfection of the same cells with H-ras (Val-12) produced morphologically transformed colonies that had 20- to 40-fold higher levels of H-ras oncogene expression. Thus transformation in this system is dependent on high levels of H-ras oncogene expression rather than on the presence of activated H-ras and c-myc oncogenes in the same cell.

  17. S(+)-ibuprofen destabilizes MYC/MYCN and AKT, increases p53 expression, and induces unfolded protein response and favorable phenotype in neuroblastoma cell lines

    PubMed Central

    IKEGAKI, NAOHIKO; HICKS, SAKEENAH L.; REGAN, PAUL L.; JACOBS, JOSHUA; JUMBO, AMINA S.; LEONHARDT, PAYTON; RAPPAPORT, ERIC F.; TANG, XAO X.

    2014-01-01

    Neuroblastoma is a common pediatric solid tumor that exhibits a striking clinical bipolarity favorable and unfavorable. The survival rate of children with unfavorable neuroblastoma remains low among all childhood cancers. MYCN and MYC play a crucial role in determining the malignancy of unfavorable neuroblastomas, whereas high-level expression of the favorable neuroblastoma genes is associated with a good disease outcome and confers growth suppression of neuroblastoma cells. A small fraction of neuroblastomas harbors TP53 mutations at diagnosis, but a higher proportion of the relapse cases acquire TP53 mutations. In this study, we investigated the effect of S(+)-ibuprofen on neuroblastoma cell lines, focusing on the expression of the MYCN, MYC, AKT, p53 proteins and the favorable neuroblastoma genes in vitro as biomarkers of malignancy. Treatment of neuroblastoma cell lines with S(+)-ibuprofen resulted in a significant growth suppression. This growth effect was accompanied by a marked decrease in the expression of MYC, MYCN, AKT and an increase in p53 expression in neuroblastoma cell lines without TP53 mutation. In addition, S(+)-ibuprofen enhanced the expression of some favorable neuroblastoma genes (EPHB6, CD44) and genes involved in growth suppression and differentiation (EGR1, EPHA2, NRG1 and SEL1L). Gene expression profile and Ingenuity pathway analyses using TP53-mutated SKNAS cells further revealed that S(+)-ibuprofen suppressed molecular pathways associated with cell growth and conversely enhanced those of cell cycle arrest and the unfolded protein response. Collectively, these results suggest that S(+)-ibuprofen or its related compounds may have the potential for therapeutic and/or palliative use for unfavorable neuroblastoma. PMID:24173829

  18. Myc in mammalian epidermis

    PubMed Central

    Watt, Fiona M.; Frye, Michaela; Benitah, Salvador Aznar

    2008-01-01

    Preface 10 years ago it was reported that overexpression of the oncogene c-Myc in human epidermal stem cells stimulates differentiation rather than uncontrolled proliferation. This was, understandably, greeted with scepticism by researchers. However, subsequent studies have confirmed that Myc can stimulate epidermal stem cells to differentiate and shed light on the underlying mechanisms. Two cancer relevant concepts emerge. First, Myc regulates similar genes in different cell types, but the biological consequences are context-dependent. Second, Myc activation is not a simple ‘on/off’ switch. The cellular response depends on the strength and duration of Myc activity, which in turn is affected by the multiple cofactors and regulatory pathways with which Myc interacts. PMID:18292777

  19. Sin3b Interacts with Myc and Decreases Myc Levels*

    PubMed Central

    Garcia-Sanz, Pablo; Quintanilla, Andrea; Lafita, M. Carmen; Moreno-Bueno, Gema; García-Gutierrez, Lucia; Tabor, Vedrana; Varela, Ignacio; Shiio, Yuzuru; Larsson, Lars-Gunnar; Portillo, Francisco; Leon, Javier

    2014-01-01

    Myc expression is deregulated in many human cancers. A yeast two-hybrid screen has revealed that the transcriptional repressor Sin3b interacts with Myc protein. Endogenous Myc and Sin3b co-localize and interact in the nuclei of human and rat cells, as assessed by co-immunoprecipitation, immunofluorescence, and proximity ligation assay. The interaction is Max-independent. A conserved Myc region (amino acids 186–203) is required for the interaction with Sin3 proteins. Histone deacetylase 1 is recruited to Myc-Sin3b complexes, and its deacetylase activity is required for the effects of Sin3b on Myc. Myc and Sin3a/b co-occupied many sites on the chromatin of human leukemia cells, although the presence of Sin3 was not associated with gene down-regulation. In leukemia cells and fibroblasts, Sin3b silencing led to Myc up-regulation, whereas Sin3b overexpression induced Myc deacetylation and degradation. An analysis of Sin3b expression in breast tumors revealed an association between low Sin3b expression and disease progression. The data suggest that Sin3b decreases Myc protein levels upon Myc deacetylation. As Sin3b is also required for transcriptional repression by Mxd-Max complexes, our results suggest that, at least in some cell types, Sin3b limits Myc activity through two complementary activities: Mxd-dependent gene repression and reduction of Myc levels. PMID:24951594

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

    PubMed Central

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

    1997-01-01

    The oncoprotein c-Myc plays an important role in cell proliferation, transformation, inhibition of differentiation and apoptosis. These functions most likely result from the transcription factor activity of c-Myc. As a heterodimer with Max, the c-Myc protein binds to the E-box sequence (CACGTG), which is also recognized by USF dimers. In order to test differences in target gene recognition of c-Myc/Max, Max and USF dimers, we compared the DNA binding characteristics of these proteins in vitro using vaccinia viruses expressing full-length c-Myc and Max proteins. As expected, purified c-Myc/max binds specifically to a consensus E-box. The optimal conditions for DNA binding by either c-Myc/Max, Max or USF dimers differ with respect to ionic strength and Mg2+ ion concentration. Most interestingly, the c-Myc/Max complex binds with a high affinity to its natural target, the rat ODC gene, which contains two adjacent, consensus E-boxes. High affinity binding results from teh ability of c-Myc/Max dimers to bind cooperatively to these E-boxes. We propose that differential cooperative binding by E-box binding transcription factors could contribute to target gene specificity. PMID:9162900

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

    PubMed Central

    Walhout, AJM; Gubbels, JM; Bernards, R; van der Vliet PC; Timmers, HTM

    1997-01-01

    The oncoprotein c-Myc plays an important role in cell proliferation, transformation, inhibition of differentiation and apoptosis. These functions most likely result from the transcription factor activity of c-Myc. As a heterodimer with Max, the c-Myc protein binds to the E-box sequence (CACGTG), which is also recognized by USF dimers. In order to test differences in target gene recognition of c-Myc/Max, Max and USF dimers, we compared the DNA binding characteristics of these proteins in vitro using vaccinia viruses expressing full-length c-Myc and Max proteins. As expected, purified c-Myc/Max binds specifically to a consensus E-box. The optimal conditions for DNA binding by either c-Myc/Max, Max or USF dimers differ with respect to ionic strength and Mg2+ion concentration. Most interestingly, the c-Myc/Max complex binds with a high affinity to its natural target, the rat ODC gene, which contains two adjacent, consensus E-boxes. High affinity binding results from the ability of c-Myc/Max dimers to bind cooperatively to these E-boxes. We propose that differential cooperative binding by E-box binding transcription factors could contribute to target gene specificity. PMID:9106360

  2. Developmental expression of the N-myc downstream regulated gene (Ndrg) family during Xenopus tropicalis embryogenesis.

    PubMed

    Zhong, Chao; Zhou, Yan-Kuan; Yang, Shan-Shan; Zhao, Jun-Fang; Zhu, Xiao-Long; Chen, Hen-Huang; Chen, Pei-Chao; Huang, Li-Quan; Huang, Xiao

    2015-01-01

    The N-myc downstream regulated gene (Ndrg) family consists of four main members Ndrg1, 2, 3, and 4. The Ndrg genes are involved in many vital biological events including development. However, comprehensive expression patterns of this gene family during vertebrate embryogenesis remain largely unknown. Here, we analyzed the Ndrg family from the evolutionary perspective and examined the expression patterns of the Ndrg genes during Xenopus tropicalis embryogenesis. Different Ndrg family members of vertebrates are separated into different homology clusters which can be further classified into two groups and each Ndrg family member is well conserved during evolution. The temporal and spatial expression patterns of Ndrg1, 2, 3 and 4 are different during early Xenopus tropicalis development. Ndrg1, 2 and 4 are maternally expressed genes while Ndrg3 is a zygotically expressed gene. The Ndrg genes are differentially expressed in the developing central nervous system, the developing sensory organs, and the developing excretory organs. Moreover, they also show other specific expression domains. Our results indicate that the Ndrg genes exhibit specific expression patterns and may play different roles during vertebrate embryogenesis.

  3. Pim1 kinase synergizes with c-MYC to induce advanced prostate carcinoma

    PubMed Central

    Wang, Jie; Kim, Jongchan; Roh, Meejeon; Franco, Omar E.; Hayward, Simon W.; Wills, Marcia L.; Abdulkadir, Sarki A.

    2010-01-01

    The oncogenic PIM1 kinase has been implicated as a cofactor for c-MYC in prostate carcinogenesis. Here we show that in human prostate tumors, coexpression of c-MYC and PIM1 is associated with higher Gleason grades. Using a tissue recombination model coupled with lentiviral-mediated gene transfer we find that Pim1 is weakly oncogenic in naïve adult mouse prostatic epithelium. However, it cooperates dramatically with c-MYC to induce prostate cancer within 6-weeks. Importantly, c-MYC/Pim1 synergy is critically dependent on Pim1 kinase activity. c-MYC/Pim1 tumors showed increased levels of the active serine-62 (S62) phosphorylated form of c-MYC. Grafts expressing a phosphomimetic c-MYCS62D mutant had higher rates of proliferation than grafts expressing wild type c-MYC but did not form tumors like c-MYC/Pim1 grafts, indicating that Pim1 cooperativity with c-MYC in vivo involves additional mechanisms other than enhancement of c-MYC activity by S62 phosphorylation. c-MYC/Pim1-induced prostate carcinomas demonstrate evidence of neuroendocrine (NE) differentiation. Additional studies, including the identification of tumor cells coexpressing androgen receptor and NE cell markers synaptophysin and Ascl1 suggested that NE tumors arose from adenocarcinoma cells through transdifferentiation. These results directly demonstrate functional cooperativity between c-MYC and PIM1 in prostate tumorigenesis in vivo and support efforts for targeting PIM1 in prostate cancer. PMID:20140016

  4. Dynamic expression of N-myc in mouse embryonic development using an enhanced green fluorescent protein reporter gene in the N-myc locus.

    PubMed

    Ma, Ming; Zhao, Kai; Wu, Wenting; Sun, Ruilin; Fei, Jian

    2014-02-01

    N-myc belongs to the Myc oncogene family and plays an essential role in mammalian embryonic development. The expression of N-myc is dynamically regulated during embryonic development; however, its expression pattern has not been well characterized due to the lack of a suitable animal model. In this paper, a genetically modified mouse model was generated in which the enhanced green fluorescent protein (EGFP) coding sequence was inserted into the N-myc locus, so that endogenous N-myc expression could be traced by the signal of EGFP. The EGFP signal in the transgenic mouse was confirmed to be consistent with the expression pattern of endogenous N-myc by fluorescence microscopy and immunohistochemical staining. Furthermore, the spatial and temporal expression of EGFP was observed in the central and peripheral nervous system, heart, lung and kidney, given the known indispensable role of N-myc in their formation. EGFP was also strongly detected in the liver, paranephros and the epithelium of the intestine. The EGFP signal can be used to trace N-myc expression in this transgenic mouse model. N-myc expression was observed in specific locations and cell lineages, and dynamically changed during embryonic development. The changing N-myc expression pattern seen in mouse embryonic development and the animal model described in this paper provide important insights and a new tool to research N-myc function.

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

    PubMed

    Wolf, Inge; Bouquet, Corinne; Melchers, Fritz

    2016-11-01

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

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

    PubMed

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

    2014-07-01

    To investigate c-myc and CCNE2 gene amplifications and their relationship in breast cancer. Sixty-six infiltrating ductal breast carcinomas with foci of ductal carcinoma in situ components collected from January 2005 to December 2007 were selected for tissue microarray and quantitative multi-gene FISH for c-myc and CCNE2 gene amplification, and the relationship with the clinicopathologic features was analyzed. Of the 66 cases, 18 (27.3%) showed c-myc amplification and 23 (34.8%) showed CCNE2 amplification. A strong correlation was found between c-myc and CCNE2 amplification (P < 0.01). The breast cancers showing c-myc and CCNE2 amplifications were all aneuploidy, and were HER2 positive (P < 0.05). Tumors with c-myc amplification also showed higher Ki-67 index (P < 0.05). C-myc and CCNE2 amplifications are common events in breast cancer, and they often coexist. C-myc and CCNE2 genes may play critical roles in the pathogenesis and development of breast cancer through unique and overlapping signaling pathways.

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

    PubMed Central

    Franco, Magdalena; Shastri, Anjali J.

    2014-01-01

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

  8. Infection by Toxoplasma gondii specifically induces host c-Myc and the genes this pivotal transcription factor regulates.

    PubMed

    Franco, Magdalena; Shastri, Anjali J; Boothroyd, John C

    2014-04-01

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

  9. Cloning of mid-G1 serum response genes and identification of a subset regulated by conditional myc expression.

    PubMed Central

    Tavtigian, S V; Zabludoff, S D; Wold, B J

    1994-01-01

    The emergence of cells from a quiescent G0 arrested state into the cell cycle is a multistep process that begins with the immediate early response to mitogens and extends into a specialized G1 phase. Many immediate early serum response genes including c-fos, c-myc, and c-jun are transcriptional regulators. To understand their roles in regulating cell cycle entry and progression, the identities of their regulatory targets must be determined. In this work we have cloned cDNA copies of messenger RNAs that are either up- or down-regulated at a mid-G1 point in the serum response (midserum-response [mid-SR]). The mid-SR panel is expected to include both direct and indirect targets of immediate early regulators. This expectation was confirmed by the identification of several transcriptional targets of conditional c-myc activity. In terms of cellular function, the mid-SR class is also expected to include execution genes needed for progression through G1 and into S-phase. DNA sequence data showed that the mid-SR panel included several genes already known to be involved in cell cycle progression or growth transformation, suggesting that previously unknown cDNAs in the same group are good candidates for other G1 execution functions. In functional assays of G0-->S-phase progression, c-myc expression can bypass the requirement for serum mitogens and drive a large fraction of G0 arrested cells through G1 into S-phase. However, beyond this general similarity, little is known about the relation of a serum-driven progression to a myc-driven progression. Using the mid-SR collection as molecular reporters, we found that the myc driven G1 differs qualitatively from the serum driven case. Instead of simply activating a subset of serum response genes, as might be expected, myc regulated some genes inversely relative to serum stimulation. This suggests that a myc driven progression from G0 may have novel properties with implications for its action in oncogenesis. Images PMID:8049528

  10. Overexpression of OsMYC2 Results in the Up-Regulation of Early JA-Rresponsive Genes and Bacterial Blight Resistance in Rice.

    PubMed

    Uji, Yuya; Taniguchi, Shiduku; Tamaoki, Daisuke; Shishido, Hodaka; Akimitsu, Kazuya; Gomi, Kenji

    2016-09-01

    JASMONATE ZIM-domain (JAZ) proteins act as transcriptional repressors of jasmonic acid (JA) responses and play a crucial role in the regulation of host immunity in plants. Here, we report that OsMYC2, a JAZ-interacting transcription factor in rice (Oryza sativa L.), plays an important role in the resistance response against rice bacterial blight, which is one of the most serious diseases in rice, caused by Xanthomonas oryzae pv. oryzae (Xoo). The results showed that OsMYC2 interacted with some OsJAZ proteins in a JAZ-interacting domain (JID)-dependent manner. The up-regulation of OsMYC2 in response to JA was regulated by OsJAZ8. Transgenic rice plants overexpressing OsMYC2 exhibited a JA-hypersensitive phenotype and were more resistant to Xoo. A large-scale microarray analysis revealed that OsMYC2 up-regulated OsJAZ10 as well as many other defense-related genes. OsMYC2 selectively bound to the G-box-like motif of the OsJAZ10 promoter in vivo and regulated the expression of early JA-responsive genes, but not of late JA-responsive genes. The nuclear localization of OsMYC2 depended on a nuclear localization signal within JID. Overall, we conclude that OsMYC2 acts as a positive regulator of early JA signals in the JA-induced resistance against Xoo in rice.

  11. Distinctive patterns of Her-2/neu, c-myc, and cyclin D1 gene amplification by fluorescence in situ hybridization in primary human breast cancers.

    PubMed

    Janocko, L E; Brown, K A; Smith, C A; Gu, L P; Pollice, A A; Singh, S G; Julian, T; Wolmark, N; Sweeney, L; Silverman, J F; Shackney, S E

    2001-06-15

    Human solid tumors undergo clonal evolution as they progress, but evidence for specific sequences of genetic changes that occur in individual tumors and are recapitulated in other tumors is difficult to obtain. Patterns of amplification of Her-2/neu, c-myc, and cyclin D1 were determined by fluorescence in situ hybridization (FISH) in relation to the presence of p53 dysfunction and ploidy in 60 primary human breast cancers. We show that there are clusters of genophenotypic abnormalities that distinguish lobular breast cancers from nonlobular tumors; that cyclin D1 amplification occurs prior to the divergence of lobular breast cancers from nonlobular cancers; that p53 dysfunction, Her-2/neu amplification, and c-myc amplification are characteristic features of nonlobular breast cancers, but not of lobular breast cancers; and that the frequencies of amplification of all three oncogenes examined increase progressively with increasing aneuploidy, but that each gene exhibits a different profile of increasing amplification in relation to tumor progression. Early amplification of c-myc appears to be an especially prominent feature of hypertetraploid/hypertetrasomic tumors. The data suggest that in tumors containing multiple abnormalities, these abnormalities often accumulate in the same cells within each tumor. Furthermore, the same patterns of accumulation of multiple genophenotypic abnormalities are recapitulated in different tumors.

  12. Down-regulation of c-myc gene expression with induction of high molecular weight DNA fragments by fluorodeoxyuridine.

    PubMed

    Li, Z R; Yin, M B; Arredondo, M A; Schöber, C; Rustum, Y M

    1994-07-19

    5-Fluoro-2'-deoxyuridine (FdUrd), a potent inhibitor of thymidylate synthase, induces extensive bulk DNA damage at drug concentrations that produce significant in vitro growth inhibition of human ileocecal carcinoma (HCT-8) cells. Constant- and pulsed-field gel electrophoresis (CFGE and PFGE), to detect size distribution of DNA double-strand breaks and repair kinetics, in parallel with northern and western blot analyses, to quantitate c-myc gene and protein expression, were utilized to analyze drug effects. At 24-hr post in vitro drug treatment, when maximum bulk DNA damage was detected, FdUrd produced a broad range of high molecular weight DNA fragments, clustering between 0.1 and 5.7 megabases in size, and resulted in a decrease in the level of c-myc transcripts and protein with no significant effect on the level of v-myc and H-ras. These effects preceded the observed cellular growth inhibition. Addition of the reduced folate leucovorin potentiated the effects induced by FdUrd, indicating that thymidylate synthase inhibition is an important initial step in drug effect followed by DNA fragmentation and suppression of c-myc expression. Changes in the integrity of the genetic materials and regulatory genes occurred prior to the observed cell growth inhibition by FdUrd, suggesting that these molecular alterations by FdUrd may be associated with subsequent FdUrd-induced cell growth inhibition.

  13. c-Myc regulates the coordinated transcription of brain disease-related PDCD10-SERPINI1 bidirectional gene pair.

    PubMed

    Chen, Ping-Yen; Chang, Wun-Shaing W; Lai, Yiu-Kay; Wu, Cheng-Wen

    2009-09-01

    Two brain disease-related genes, one coding for the protease inhibitor SERPINI1 which is down-regulated in brain tumors, and the other for the PDCD10 programmed cell death gene which is often mutated in cerebral cavernous malformation, are closely adjacent in a head-to-head configuration and separated by only 851 bp on human chromosome 3q26. The 851-bp intergenic region contains a GC-rich 175-bp minimal bidirectional promoter which is essential for transcriptional activation of the two flanking genes. The oncogenic c-Myc transcription factor was identified to bind to a non-canonical E-box element (5'-CATGCG-3') of the minimal bidirectional promoter to drive both gene expressions. Methylation at the specific C nucleotide within the E-box sequence (5'-CATG(m)CG-3'), however, would severely interfere with the binding of c-Myc to the E-box. These results suggest that c-Myc plays an important role in regulating the coordinated transcription of the PDCD10-SERPINI1 bidirectional gene pair, and is possibly involved in differential expressions of these two neighboring genes in central nervous system diseases such as brain cancer.

  14. 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.

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

    PubMed

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

    2016-12-13

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

  16. c-Myc deregulation induces mRNA capping enzyme dependency

    PubMed Central

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

    2016-01-01

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

  17. The spliceosome is a therapeutic vulnerability in MYC-driven cancer

    PubMed Central

    Hsu, Tiffany Y-T.; Simon, Lukas M.; Neill, Nicholas; Marcotte, Richard; Sayad, Azin; Bland, Christopher S.; Echeverria, Gloria V.; Sun, Tingting; Kurley, Sarah J.; Tyagi, Siddhartha; Karlin, Kristen L.; Dominguez-Vidaña, Rocio; Hartman, Jessica D.; Renwick, Alexander; Scorsone, Kathleen; Bernardi, Ronald J.; Skinner, Samuel O.; Jain, Antrix; Orellana, Mayra; Lagisetti, Chandraiah; Golding, Ido; Jung, Sung Y.; Neilson, Joel R.; Zhang, Xiang H.-F.; Cooper, Thomas A.; Webb, Thomas R.; Neel, Benjamin G.; Shaw, Chad A.; Westbrook, Thomas F.

    2016-01-01

    c-MYC (MYC) overexpression or hyperactivation is one of the most common drivers of human cancer. Despite intensive study, the MYC oncogene remains recalcitrant to therapeutic inhibition. MYC is a transcription factor, and many of its pro-tumorigenic functions have been attributed to its ability to regulate gene expression programs1–3. Notably, oncogenic MYC activation has also been shown to increase total RNA and protein production in many tissue and disease contexts4–7. While such increases in RNA and protein production may endow cancer cells with pro-tumor hallmarks, this elevation in synthesis may also generate new or heightened burden on MYC-driven cancer cells to properly process these macromolecules8. Herein, we discover the spliceosome as a new target of oncogenic stress in MYC-driven cancers. We identify BUD31 as a MYC-synthetic lethal gene, and demonstrate that BUD31 is a component of the core spliceosome required for its assembly and catalytic activity. Core spliceosomal factors (SF3B1, U2AF1, and others) associated with BUD31 are also required to tolerate oncogenic MYC. Notably, MYC hyperactivation induces an increase in total pre-mRNA synthesis, suggesting an increased burden on the core spliceosome to process pre-mRNA. In contrast to normal cells, partial inhibition of the spliceosome in MYC-hyperactivated cells leads to global intron retention, widespread defects in pre-mRNA maturation, and deregulation of many essential cell processes. Importantly, genetic or pharmacologic inhibition of the spliceosome in vivo impairs survival, tumorigenicity, and metastatic proclivity of MYC-dependent breast cancers. Collectively, these data suggest that oncogenic MYC confers a collateral stress on splicing and that components of the spliceosome may be therapeutic entry points for aggressive MYC-driven cancers. PMID:26331541

  18. [Abnormal expression of c-myc, p53, p16 protein and GNAS1 gene mutation in fibrous dysplasia].

    PubMed

    Tang, Juan; Zhao, Hong-ye; Zheng, Li; Zhang, Hui-zhen; Jiang, Zhi-ming

    2009-05-01

    To study the significance of c-myc, p53 and p16 protein expression in fibrous dysplasia, to detect the GNAS1 gene mutation in fibrous dysplasia, and to explore the property of fibrous dysplasia. The expression of c-myc, p53 and p16 protein was evaluated by immunohistochemistry SP method in 35 cases of fibrous dysplasia including 1 FD with malignancy, 1 Mazabraud syndrome and 20 control cases (10 cases of bony callus, 10 cases of osteosarcoma). Genomic DNA extraction, PCR amplification and gene sequencing were used to detect GNAS1 gene mutation in 35 cases of fibrous dysplasia. C-myc protein immunoreactivity was detected in 91 percentage of FD (P = 0.001). Compared with the negative control group, the difference was significant. P16 positive was detected in 34 FD cases (P = 0.001). The difference was significant as compared with the positive control group. Positive p53 protein expression was detected in the only 1 case of fibrous dysplasia with malignant transformation. PCR amplification was successful in 12 of 35 FD cases. Two of the 12 FD cases were detected to have GNAS1 gene mutation, in which 1 case was FD of Mazabraud syndrome, 1 case was a monostotic lesion. C-myc could be another protooncogene in addition to c-fos in the fibrous dysplasia disease. P53 protein overexpression could be useful in the diagnosis of FD malignancy and in the prediction of the prognosis of FD. The abnormal expression of the gene p16 might play an important role in the formation of FD. The GNAS1 mutation exist in FD. All of the results indicate that FD could be a neoplasia disease, caused by multiple factors leading to a dysfunction of bone development.

  19. 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. © 2015 The Authors The Plant Journal © 2015 John Wiley & Sons Ltd.

  20. 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

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

    PubMed

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

    2015-10-13

    The c-Myc gene codes for a basic-helix-loop-helix-leucine zipper transcription factor protein and is reported to be frequently over-expressed in human cancers. Given that c-Myc plays an essential role in neoplastic transformation we wished to define its activity in lung cancer and therefore studied its targeted expression to respiratory epithelium in a transgenic mouse disease model. Using histological well-defined tumors, transcriptome analysis identified novel c-Myc responsive cell cycle and apoptosis genes that were validated as direct c-Myc targets using EMSA, Western blotting, gene reporter and ChIP assays.Through computational analyses c-Myc cooperating transcription factors emerged for repressed and up-regulated genes in cancer samples, namely Klf7, Gata3, Sox18, p53 and Elf5 and Cebpα, respectively. Conversely, at promoters of genes regulated in transgenic but non-carcinomatous lung tissue enriched binding sites for c-Myc, Hbp1, Hif1 were observed. Bioinformatic analysis of tumor transcriptomic data revealed regulatory gene networks and highlighted mortalin and moesin as master regulators while gene reporter and ChIP assays in the H1299 lung cancer cell line as well as cross-examination of published ChIP-sequence data of 7 human and 2 mouse cell lines provided strong evidence for the identified genes to be c-Myc targets. The clinical significance of findings was established by evaluating expression of orthologous proteins in human lung cancer. Taken collectively, a molecular circuit for c-Myc-dependent cellular transformation was identified and the network analysis broadened the perspective for molecularly targeted therapies.

  2. N-myc downstream-regulated gene 1 (NDRG1) a differentiation marker of human breast cancer.

    PubMed

    Fotovati, Abbas; Abu-Ali, Samah; Kage, Masayoshi; Shirouzu, Kazuo; Yamana, Hideaki; Kuwano, Michihiko

    2011-09-01

    N-myc downstream-regulated gene 1 (NDRG1), also called differentiation-related gene-1 (Drg1) and Cap43, is expressed in various normal tissues and suppressed in several malignancies. In this study, whether NDRG1 expression was correlated with differentiation of human breast cancer cells has been investigated. Endogenous expression level of NDRG1 was closely correlated with differentiation status of breast cancer cell lines. Furthermore, sodium butyrate (NaB), an inducer of cellular differentiation, increased the expression of β-casein, a milk-related differentiation marker, together with up-regulation of NDRG1 in breast cancer cells. In contrast, inhibition of NDRG1 by its siRNA resulted in reduced accumulation of β-casein. Immunohistochemical analysis showed co-expression of NDRG1 and β-casein or milk fat protein (MFP), another differentiation marker of breast tissue, in the mouse xenograft model of breast cancer. Furthermore, overexpression of NDRG1 expanded the differentiated area in the xenograft model of breast cancer. In human breast cancer, using samples from 45 patients, we also showed close relationship between NDRG1 and β-casein or MFP expression. Altogether, in vitro and in vivo data demonstrated a possible role of NDRG1 in differentiation of breast cancer. We concluded that NDRG1 could be used as a biomarker for differentiation of breast cancer for both diagnostic and therapeutic purposes.

  3. 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

  4. Insertional Mutagenesis and Deep Profiling Reveals Gene Hierarchies and a Myc/p53-Dependent Bottleneck in Lymphomagenesis

    PubMed Central

    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.

    2014-01-01

    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

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

    PubMed

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

    2011-07-01

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

  6. Estrogen Induces c-myc Gene Expression via an Upstream Enhancer Activated by the Estrogen Receptor and the AP-1 Transcription Factor

    PubMed Central

    Wang, Chunyu; Mayer, Julie Ann; Mazumdar, Abhijit; Fertuck, Kirsten; Kim, Heetae; Brown, Myles

    2011-01-01

    c-myc oncogene is implicated in tumorigenesis of many cancers, including breast cancer. Although c-myc is a well-known estrogen-induced gene, its promoter has no estrogen-response element, and the underlying mechanism by which estrogen induces its expression remains obscure. Recent genome-wide studies by us and others suggested that distant elements may mediate estrogen induction of gene expression. In this study, we investigated the molecular mechanism by which estrogen induces c-myc expression with a focus on these distal elements. Estrogen rapidly induced c-myc expression in estrogen receptor (ER)-positive breast cancer cells. Although estrogen had little effect on c-myc proximal promoter activity, it did stimulate the activity of a luciferase reporter containing a distal 67-kb enhancer. Estrogen induction of this luciferase reporter was dependent upon both a half-estrogen response element and an activator protein 1 (AP-1) site within this enhancer, which are conserved across 11 different mammalian species. Small interfering RNA experiments and chromatin immunoprecipitation assays demonstrated the necessity of ER and AP-1 cross talk for estrogen to induce c-myc expression. TAM67, the AP-1 dominant negative, partially inhibited estrogen induction of c-myc expression and suppressed estrogen-induced cell cycle progression. Together, these results demonstrate a novel pathway of estrogen regulation of gene expression by cooperation between ER and AP-1 at the distal enhancer element and that AP-1 is involved in estrogen induction of the c-myc oncogene. These results solve the long-standing question in the field of endocrinology of how estrogen induces c-myc expression. PMID:21835891

  7. Cytoplasmic calcium increase via fusion with inactivated Sendai virus induces apoptosis in human multiple myeloma cells by downregulation of c-Myc oncogene

    PubMed Central

    Jiang, Yingzhe; Saga, Kotaro; Miyamoto, Yasuhide; Kaneda, Yasufumi

    2016-01-01

    Because the emergence of drug resistance is a major limitation of current treatments for multiple myeloma (MM), it is necessary to continuously develop novel anticancer strategies. Here, using an inactivated Sendai virus (Hemagglutinating Virus of Japan; HVJ) envelope (HVJ-E), we discovered that increase of cytoplasmic Ca2+ by virus-cell fusion significantly induced apoptosis against human MM cells but not peripheral blood mononuclear cells from healthy donors. Interaction of F protein of HVJ-E with MM cells increased intracellular Ca2+ level of MMs by the induction of Ca2+ efflux from endoplasmic reticulum but not influx from extracellular region. The elevation of the Ca2+ cytoplasmic level induced SMAD1/5/8 phosphorylation and translocation into the nucleus, and SMAD1/5/8 and SMAD4 complex suppressed c-Myc transcription. Meanwhile, HVJ-E decreases S62 phosphorylation of c-Myc and promotes c-Myc protein degradation. Thus, HVJ-E-induced cell death of MM resulted from suppression of c-Myc by both destabilization of c-Myc protein and downregulation of c-Myc transcription. This study indicates that HVJ-E will be a promising tool for MM therapy. PMID:27145280

  8. Expression of N-myc downstream regulated gene 1 (NDRG1) in central neurocytoma.

    PubMed

    Fotovati, Abbas; Abu-Ali, Samah; Sugita, Yasuo; Nakamura, Yasuhiro

    2011-10-01

    N-myc downstream regulated gene 1 (NDRG1), also known as Cap43, Drg-1, and rit42, is expressed in various normal tissues and cancers, in which it is often associated with a favorable prognosis. It also plays a critical role in central nervous system development, with NDRG1 deficiency resulting in neural defects in mice. Central neurocytoma (CN) is a relatively rare tumor of the neurocytes in the brain, which occurs mainly in young adults. In the present study, we found that tissue samples from four patients with CN had both nuclear and cytoplasmic/membranous expression of NDRG1 protein in highly differentiated CN tumor cells. NDRG1 was also expressed in intratumoral microvessels. Immunohistochemical study of serial sections from the same patients revealed a marked association between the expression pattern of NDRG1 and that of neuron-specific enolase, a tumor differentiation marker. The data presented in this study suggest that NDRG1 could be considered a potential differentiation marker for CN.

  9. Role of DLC1 tumor suppressor gene and MYC oncogene in pathogenesis of human hepatocellular carcinoma: potential prospects for combined targeted therapeutics (review).

    PubMed

    Zimonjic, Drazen B; Popescu, Nicholas C

    2012-08-01

    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

  10. 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.

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

    PubMed Central

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

    2012-01-01

    The upregulation or mutation of C-MYC has been observed in gastric, colon, breast, and lung tumors and in Burkitt’s lymphoma. However, little is known about the role C-MYC plays in gastric adenocarcinoma. In the present study, we intended to investigate the influence of C-MYC on the growth, proliferation, apoptosis, invasion, and cell cycle of the gastric cancer cell line SGC7901 and the gastric cell line HFE145. C-MYC cDNA was subcloned into a constitutive vector PCDNA3.1 followed by transfection in normal gastric cell line HFE145 by using liposome. Then stable transfectants were selected and appraised. Specific inhibition of C-MYC was achieved using a vector-based siRNA system which was transfected in gastric cancer cell line SGC7901. The apoptosis and cell cycles of these clones were analyzed by using flow cytometric assay. The growth and proliferation were analyzed by cell growth curves and colony-forming assay, respectively. The invasion of these clones was analyzed by using cell migration assay. The C-MYC stable expression clones (HFE-Myc) and C-MYC RNAi cells (SGC-MR) were detected and compared with their control groups, respectively. HFE-Myc grew faster than HFE145 and HFE-PC (HFE145 transfected with PCDNA3.1 vector). SGC-MR1, 2 grew slower than SGC7901 and SGC-MS1, 2 (SGC7901 transfected with scrambled control duplexes). The cell counts of HFE-Myc in the third, fourth, fifth, sixth, and seventh days were significantly more than those of control groups (P < 0.05). Those of SGC-MR1, 2 in the fourth, fifth, sixth, and seventh days were significantly fewer than those of control groups (P < 0.05). Cell cycle analysis showed that proportions of HFE-Myc and SGC-MR cells in G0–G1 and G2–M were different significantly with their control groups, respectively (P < 0.05). The apoptosis rate of HFE-Myc was significantly higher than those of control groups (P < 0.05). Results of colony-forming assay showed that the colony formation rate of HFE-Myc was higher than

  12. Long-distance interaction of the integrated HPV fragment with MYC gene and 8q24.22 region upregulating the allele-specific MYC expression in HeLa cells.

    PubMed

    Shen, Congle; Liu, Yongzhen; Shi, Shu; Zhang, Ruiyang; Zhang, Ting; Xu, Qiang; Zhu, Pengfei; Chen, Xiangmei; Lu, Fengmin

    2017-08-01

    Human papillomavirus (HPV) infection is the most important risk factor for cervical cancer development. In HeLa cell line, the HPV viral genome is integrated at 8q24 in one allele of chromosome 8. It has been reported that the HPV fragment integrated in HeLa genome can cis-activate the expression of proto-oncogene MYC, which is located at 500 kb downstream of the integrated site. However, the underlying molecular mechanism of this regulation is unknown. A recent study reported that MYC was highly expressed exclusively from the HPV-integrated haplotype, and a long-range chromatin interaction between the integrated HPV fragment and MYC gene has been hypothesized. In this study, we provided the experimental evidences supporting this long-range chromatin interaction in HeLa cells by using Chromosome Conformation Capture (3C) method. We found that the integrated HPV fragment, MYC and 8q24.22 was close to each other and might form a trimer in spatial location. When knocking out the integrated HPV fragment or 8q24.22 region from chromosome 8 by CRISPR/Cas9 system, the expression of MYC reduced dramatically in HeLa cells. Interestingly, decreased expression was only observed in three from eight cell clones, when only one 8q24.22 allele was knocked out. Functionally, HPV knockout caused senescence-associated acidic β-gal activity in HeLa cells. These data indicate a long-distance interaction of the integrated HPV fragment with MYC gene and 8q24.22 region, providing an alternative mechanism relevant to the carcinogenicity of HPV integration. © 2017 The Authors International Journal of Cancer published by John Wiley & Sons Ltd on behalf of UICC.

  13. Sin3b interacts with Myc and decreases Myc levels.

    PubMed

    Garcia-Sanz, Pablo; Quintanilla, Andrea; Lafita, M Carmen; Moreno-Bueno, Gema; García-Gutierrez, Lucia; Tabor, Vedrana; Varela, Ignacio; Shiio, Yuzuru; Larsson, Lars-Gunnar; Portillo, Francisco; Leon, Javier

    2014-08-08

    Myc expression is deregulated in many human cancers. A yeast two-hybrid screen has revealed that the transcriptional repressor Sin3b interacts with Myc protein. Endogenous Myc and Sin3b co-localize and interact in the nuclei of human and rat cells, as assessed by co-immunoprecipitation, immunofluorescence, and proximity ligation assay. The interaction is Max-independent. A conserved Myc region (amino acids 186-203) is required for the interaction with Sin3 proteins. Histone deacetylase 1 is recruited to Myc-Sin3b complexes, and its deacetylase activity is required for the effects of Sin3b on Myc. Myc and Sin3a/b co-occupied many sites on the chromatin of human leukemia cells, although the presence of Sin3 was not associated with gene down-regulation. In leukemia cells and fibroblasts, Sin3b silencing led to Myc up-regulation, whereas Sin3b overexpression induced Myc deacetylation and degradation. An analysis of Sin3b expression in breast tumors revealed an association between low Sin3b expression and disease progression. The data suggest that Sin3b decreases Myc protein levels upon Myc deacetylation. As Sin3b is also required for transcriptional repression by Mxd-Max complexes, our results suggest that, at least in some cell types, Sin3b limits Myc activity through two complementary activities: Mxd-dependent gene repression and reduction of Myc levels. © 2014 by The American Society for Biochemistry and Molecular Biology, Inc.

  14. c-Myc represses FOXO3a-mediated transcription of the gene encoding the p27(Kip1) cyclin dependent kinase inhibitor.

    PubMed

    Chandramohan, Vidyalakshmi; Mineva, Nora D; Burke, Brian; Jeay, Sébastien; Wu, Min; Shen, Jian; Yang, William; Hann, Stephen R; Sonenshein, Gail E

    2008-08-15

    The p27(Kip1) (p27) cyclin-dependent kinase inhibitor and c-Myc oncoprotein play essential roles in control of cell cycle progression and apoptosis. Induction of p27 (CDKN1B) gene transcription by Forkhead box O proteins such as FOXO3a leads to growth arrest and apoptosis. Previously, we observed that B cell receptor (surface IgM) engagement of WEHI 231 immature B lymphoma cells with an anti-IgM antibody results in activation of FOXO3a, growth arrest and apoptosis. As ectopic c-Myc expression in these cells prevented anti-IgM induction of p27 and cell death, we hypothesized that c-Myc represses FOXO3a-mediated transcription. Here we show that c-Myc inhibits FOXO3a-mediated activation of the p27 promoter in multiple cell lines. The mechanism of this repression was explored using a combination of co-immunoprecipitation, oligonucleotide precipitation, and chromatin immunoprecipitation experiments. The studies demonstrate a functional association of FOXO3a and c-Myc on a proximal Forkhead binding element in the p27 promoter. This association involves the Myc box II domain of c-Myc and the N-terminal DNA-binding portion of FOXO3a. Analysis of publicly available microarray datasets showed an inverse pattern of c-MYC and p27 RNA expression in primary acute myeloid leukemia, prostate cancer and tongue squamous cell carcinoma samples. The inhibition of FOXO3a-mediated activation of the p27 gene by the high aberrant expression of c-Myc in many tumor cells likely contributes to their uncontrolled proliferation and invasive phenotype.

  15. 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

  16. ISL1, a novel regulator of CCNB1, CCNB2 and c-MYC genes, promotes gastric cancer cell proliferation and tumor growth.

    PubMed

    Shi, Qiong; Wang, Weiping; Jia, Zhuqing; Chen, Ping; Ma, Kangtao; Zhou, Chunyan

    2016-06-14

    Islet-1 (ISL1) belongs to the LIM homeodomain transcription factor family, which is specifically expressed in certain tissue types only. Previously, we reported that ISL1 is aberrantly overexpressed in gastric cancer (GC). However, its role in GC is not clear. Here, we report that ISL1 is aberrantly upregulated not only in human gastric carcinoma tissues but also in some GC cell lines. Upregulated ISL1 expression enhanced xenografted gastric carcinoma development, while ISL1 knockdown inhibited GC growth in nude mice. ISL1 overexpression promoted GC cell proliferation, colony formation, and cell growth in soft agar, and facilitated cell cycle transition in GC cells, demonstrated an increase in the proportion of cells in the G2/M and S phases and a decrease in the proportion of cells in the G1 phase. Furthermore, we provide evidence that ISL1 is a novel regulator of the cyclin B1 (CCNB1), cyclin B2 (CCNB2) and c-myc (c-MYC) genes. ISL1 activated the expression of these genes in GC cells by binding to the conserved binding sites on their promoters or enhancers. The expression levels of the genes were decreased in response to ISL1 knockdown. Therefore, ISL1 may serve as a potential therapeutic target in GC.

  17. SIRT1 Promotes N-Myc Oncogenesis through a Positive Feedback Loop Involving the Effects of MKP3 and ERK on N-Myc Protein Stability

    PubMed Central

    Gherardi, Samuele; Scarlett, Christopher J.; Bedalov, Antonio; Xu, Ning; Iraci, Nuncio; Valli, Emanuele; Ling, Dora; Thomas, Wayne; van Bekkum, Margo; Sekyere, Eric; Jankowski, Kacper; Trahair, Toby; MacKenzie, Karen L.; Haber, Michelle; Norris, Murray D.; Biankin, Andrew V.; Perini, Giovanni; Liu, Tao

    2011-01-01

    The N-Myc oncoprotein is a critical factor in neuroblastoma tumorigenesis which requires additional mechanisms converting a low-level to a high-level N-Myc expression. N-Myc protein is stabilized when phosphorylated at Serine 62 by phosphorylated ERK protein. Here we describe a novel positive feedback loop whereby N-Myc directly induced the transcription of the class III histone deacetylase SIRT1, which in turn increased N-Myc protein stability. SIRT1 binds to Myc Box I domain of N-Myc protein to form a novel transcriptional repressor complex at gene promoter of mitogen-activated protein kinase phosphatase 3 (MKP3), leading to transcriptional repression of MKP3, ERK protein phosphorylation, N-Myc protein phosphorylation at Serine 62, and N-Myc protein stabilization. Importantly, SIRT1 was up-regulated, MKP3 down-regulated, in pre-cancerous cells, and preventative treatment with the SIRT1 inhibitor Cambinol reduced tumorigenesis in TH-MYCN transgenic mice. Our data demonstrate the important roles of SIRT1 in N-Myc oncogenesis and SIRT1 inhibitors in the prevention and therapy of N-Myc–induced neuroblastoma. PMID:21698133

  18. 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

  19. c-myc Gene Copy Number Variation in Cervical Exfoliated Cells Detected on Fluorescence in situ Hybridization for Cervical Cancer Screening.

    PubMed

    Zhao, Wei-Hong; Hao, Min; Cheng, Xiao-Tong; Yang, Xin; Wang, Zhi-Lian; Cheng, Ke-Yan; Liu, Fang-Li; Bai, Yao-Xian

    2016-01-01

    This study assessed the clinical significance of c-myc gene copy number gain detected by fluorescence in situ hybridization (FISH) in the prediction of cervical intraepithelial neoplasia (CIN) progression. We retrospectively investigated 140 Thinprep cytologic test (TCT) specimens that were histopathologically diagnosed with various stages of cervical neoplasia or malignancy. The specimens were subjected to TCT, human papillomavirus (HPV) testing, and FISH analysis with a c-myc-specific probe. The diagnostic reliability of these methods in determining progression was assessed according to sensitivity, specificity, and κ coefficients. The gene copy number gain of c-myc was significantly higher in the cervical lesion of advanced histologic grade (p < 0.001). For CIN2+ lesions, the sensitivities of TCT, HPV DNA testing, and FISH analysis were 72.3, 92.1, and 64.5%, respectively; the specificities were 81.3, 57.8, and 93.8%, respectively (p < 0.001). The κ coefficients between the c-myc gene test and either the TCT or the HPV DNA test were 0.538 and 0.399, respectively (p < 0.001). FISH analysis of the c-myc oncogene could be a useful adjunct screening method for the early diagnosis of high-grade cervical lesions. Moreover, c-myc may be a new molecular biomarker for the early diagnosis of cervical lesion progression. © 2016 S. Karger AG, Basel.

  20. A re-emerging marker for prognosis in hepatocellular carcinoma: the add-value of fishing c-myc gene for early relapse.

    PubMed

    Pedica, Federica; Ruzzenente, Andrea; Bagante, Fabio; Capelli, Paola; Cataldo, Ivana; Pedron, Serena; Iacono, Calogero; Chilosi, Marco; Scarpa, Aldo; Brunelli, Matteo; Tomezzoli, Anna; Martignoni, Guido; Guglielmi, Alfredo

    2013-01-01

    Hepatocellular carcinoma is one leading cause of cancer-related death and surgical resection is still one of the major curative therapies. Recently, there has been a major effort to find mechanisms involved in carcinogenesis and early relapse. c-myc gene abnormality is found in hepatocarcinogenesis. Our aim was to analyze the role of c-myc as prognostic factor in terms of overall survival and disease-free survival and to investigate if c-myc may be an important target for therapy. We studied sixty-five hepatocellular carcinomas submitted to surgical resection with curative intent. Size, macro-microvascular invasion, necrosis, number of nodules, grading and serum alfa-fetoprotein level were registered for all cases. We evaluated the c-myc aberrations by using break-apart FISH probes. Probes specific for the centromeric part of chromosome 8 and for the locus specific c-myc gene (8q24) were used to assess disomy, gains of chromosomes (polysomy due to polyploidy) and amplification. c-myc gene amplification was scored as 8q24/CEP8 > 2. Statistical analysis for disease-free survival and overall survival were performed. At molecular level, c-myc was amplified in 19% of hepatocellular carcinoma, whereas showed gains in 55% and set wild in 26% of cases. The 1- and 3-year disease-free survival and overall survival for disomic, polysomic and amplified groups were significantly different (p=0.020 and p=.018 respectively). Multivariate analysis verified that the AFP and c-myc status (amplified vs. not amplified) were significant prognostic factors for overall patients survival. c-myc gene amplification is significantly correlated with disease-free survival and overall survival in patients with hepatocellular carcinoma after surgical resection and this model identifies patients with risk of early relapse (≤12 months). We suggest that c-myc assessment may be introduced in the clinical practice for improving prognostication (high and low risk of relapse) routinely and may have

  1. Arabidopsis basic helix-loop-helix transcription factors MYC2, MYC3, and MYC4 regulate glucosinolate biosynthesis, insect performance, and feeding behavior.

    PubMed

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

    2013-08-01

    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.

  2. Identification of functional networks of estrogen- and c-Myc-responsive genes and their relationship to response to tamoxifen therapy in breast cancer.

    PubMed

    Musgrove, Elizabeth A; Sergio, C Marcelo; Loi, Sherene; Inman, Claire K; Anderson, Luke R; Alles, M Chehani; Pinese, Mark; Caldon, C Elizabeth; Schütte, Judith; Gardiner-Garden, Margaret; Ormandy, Christopher J; McArthur, Grant; Butt, Alison J; Sutherland, Robert L

    2008-08-20

    Estrogen is a pivotal regulator of cell proliferation in the normal breast and breast cancer. Endocrine therapies targeting the estrogen receptor are effective in breast cancer, but their success is limited by intrinsic and acquired resistance. With the goal of gaining mechanistic insights into estrogen action and endocrine resistance, we classified estrogen-regulated genes by function, and determined the relationship between functionally-related genesets and the response to tamoxifen in breast cancer patients. Estrogen-responsive genes were identified by transcript profiling of MCF-7 breast cancer cells. Pathway analysis based on functional annotation of these estrogen-regulated genes identified gene signatures with known or predicted roles in cell cycle control, cell growth (i.e. ribosome biogenesis and protein synthesis), cell death/survival signaling and transcriptional regulation. Since inducible expression of c-Myc in antiestrogen-arrested cells can recapitulate many of the effects of estrogen on molecular endpoints related to cell cycle progression, the estrogen-regulated genes that were also targets of c-Myc were identified using cells inducibly expressing c-Myc. Selected genes classified as estrogen and c-Myc targets displayed similar levels of regulation by estrogen and c-Myc and were not estrogen-regulated in the presence of siMyc. Genes regulated by c-Myc accounted for 50% of all acutely estrogen-regulated genes but comprised 85% (110/129 genes) in the cell growth signature. siRNA-mediated inhibition of c-Myc induction impaired estrogen regulation of ribosome biogenesis and protein synthesis, consistent with the prediction that estrogen regulates cell growth principally via c-Myc. The 'cell cycle', 'cell growth' and 'cell death' gene signatures each identified patients with an attenuated response in a cohort of 246 tamoxifen-treated patients. In multivariate analysis the cell death signature was predictive independent of the cell cycle and cell growth

  3. Genomic amplification patterns of human telomerase RNA gene and C-MYC in liquid-based cytological specimens used for the detection of high-grade cervical intraepithelial neoplasia

    PubMed Central

    2012-01-01

    Background The amplification of oncogenes initiated by high-risk human papillomavirus (HPV) infection is an early event in cervical carcinogenesis and can be used for cervical lesion diagnosis. We measured the genomic amplification rates and the patterns of human telomerase RNA gene (TERC) and C-MYC in the liquid-based cytological specimens to evaluate the diagnostic characteristics for the detection of high-grade cervical lesions. Methods Two hundred and forty-three residual cytological specimens were obtained from outpatients aged 25 to 64 years at Qilu Hospital, Shandong University. The specimens were evaluated by fluorescence in situ hybridization (FISH) using chromosome probes to TERC (3q26) and C-MYC (8q24). All of the patients underwent colposcopic examination and histological evaluation. A Chi-square test was used for categorical data analysis. Results In the normal, cervical intraepithelial neoplasia grade 1 (CIN1), grade 2 (CIN2), grade 3 (CIN3) and squamous cervical cancer (SCC) cases, the TERC positive rates were 9.2%, 17.2%, 76.2%, 100.0% and 100.0%, respectively; the C-MYC positive rates were 20.7%, 31.0%, 71.4%, 81.8% and 100.0%, respectively. The TERC and C-MYC positive rates were higher in the CIN2+ (CIN2, CIN3 and SCC) cases than in the normal and CIN1 cases (p < 0.01). Compared with cytological analysis, the TERC test showed higher sensitivity (90.0% vs. 84.0%) and higher specificity (89.6% vs. 64.3%). The C-MYC test showed lower sensitivity (80.0% vs. 84.0%) and higher specificity (77.7% vs. 64.3%). Using a cut-off value of 5% or more aberrant cells, the TERC test showed the highest combination of sensitivity and specificity. The CIN2+ group showed more high-level TERC gene copy number (GCN) cells than did the normal/CIN1 group (p < 0.05). For C-MYC, no significant difference between the two histological categories was detected (p > 0.05). Conclusions The TERC test is highly sensitive and is therefore suitable for cervical cancer screening. The

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

    PubMed Central

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

    2011-01-01

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

  5. Increased β‑catenin and c-myc expression predict aggressive growth of non-functioning pituitary adenomas: An assessment using a tissue microarray-based approach.

    PubMed

    Liu, Chunhui; Wu, Youtu; Yu, Shengyuan; Bai, Jiwei; Li, Chuzhong; Wu, Dan; Zhang, Yazhuo

    2017-04-01

    Non-functional pituitary adenomas (NFPAs) account for 80% of pituitary adenomas with the majority of these exhibiting recurrences post-surgery. Overexpression of β-catenin and c‑myc is common in numerous invasive tumors. The present study sought to investigate the correlation of β‑catenin and c‑myc expression levels with aggressive growth and recurrence of NFPAs, using immunohistochemical examination of tissue microarrays. Tissue microarrays comprised 212 NFPAs specimens and 10 healthy specimens as controls. NFPAs were categorized as non‑aggressive or aggressive. Immunohistochemical examination was performed to determine the expression of β‑catenin and c‑myc. Correlation of the expression levels of β‑catenin and c‑myc with clinicopathological parameters, including aggressiveness and recurrence, were assessed by univariate, multivariate and logistic regression analysis. Increased expression of β‑catenin and c‑myc was detected in the majority of aggressive NFPAs specimens (71.1 and 88.7%, respectively). There was a significant positive correlation between β‑catenin and c‑myc expression and aggressiveness [P=0.001, Odds Ratio (OR)=4.011; P<0.001, OR=30.833]. Only β‑catenin expression demonstrated a significant correlation with recurrence in NFPAs (P=0.021, OR=2.571). β‑catenin and c‑myc were demonstrated to be potential biomarkers for aggressive NFPAs and in the future, β-catenin may serve as a marker for aggressive behavior and recurrence in NFPAs.

  6. 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

  7. Augmented cell survival in eutopic endometrium from women with endometriosis: Expression of c-myc, TGF-beta1 and bax genes

    PubMed Central

    Johnson, M Cecilia; Torres, Marisa; Alves, Alessandra; Bacallao, Ketty; Fuentes, Ariel; Vega, Margarita; Boric, M Angélica

    2005-01-01

    Background Endometriosis is a common gynaecological disorder characterized by the presence of endometrial tissue outside of the uterus. The fragments in normal menstruation are composed of necrotic and living cells, which do not survive in ectopic locations because of programmed cell death. The aim of this study was to evaluate if the balance between cell proliferation and apoptosis is changed in eutopic endometrium from women with endometriosis throughout the menstrual cycle by studying bax (pro-apoptotic), c-myc (regulator of cell cycle) and TGF-beta1 (involved in cell differentiation) genes. Methods Eutopic endometrium was obtained from: 30 women with endometriosis (32.8 +/- 5 years) and 34 fertile eumenorrheic women (36 +/- 5.3 years). We analyzed apoptosis (TUNEL: DNA fragmentation); cell proliferation (immunohistochemistry (IHC) for Ki67); c-myc, bax and TGF-beta1 mRNA abundance (RT-PCR) and TGF-beta1 protein (IHC) in endometrial explants. Results Cell proliferation strongly decreased from proliferative to late secretory phases in glands, but not in stroma, in both endometria. Positive staining in glands and stroma from proliferative endometrium with endometriosis was 1.9- and 2.2-fold higher than control endometrium, respectively (p < 0.05). Abundance of c-myc mRNA was 65% higher in proliferative endometrium from endometriosis than normal tissue (p < 0.05). TGF-beta1 (mRNA and protein) augmented during mid secretory phase in normal endometrium, effect not observed in endometrium with endometriosis. In normal endometrium, the percentage of apoptotic epithelial and stromal cells increased more than 30-fold during late secretory phase. In contrast, in endometrium from endometriosis, not only this increase was not observed, besides bax mRNA decreased 63% versus normal endometrium (p < 0.05). At once, in early secretory phase, apoptotic stromal cells increased 10-fold with a concomitant augment of bax mRNA abundance (42%) in endometria from endometriosis (p < 0

  8. Genes conserved in bilaterians but jointly lost with Myc during nematode evolution are enriched in cell proliferation and cell migration functions.

    PubMed

    Erives, Albert J

    2015-09-01

    Animals use a stereotypical set of developmental genes to build body architectures of varying sizes and organizational complexity. Some genes are critical to developmental patterning, while other genes are important to physiological control of growth. However, growth regulator genes may not be as important in small-bodied "micro-metazoans" such as nematodes. Nematodes use a simplified developmental strategy of lineage-based cell fate specifications to produce an adult bilaterian body composed of a few hundreds of cells. Nematodes also lost the MYC proto-oncogenic regulator of cell proliferation. To identify additional regulators of cell proliferation that were lost with MYC, we computationally screened and determined 839 high-confidence genes that are conserved in bilaterians/lost in nematodes (CIBLIN genes). We find that 30 % of all CIBLIN genes encode transcriptional regulators of cell proliferation, epithelial-to-mesenchyme transitions, and other processes. Over 50 % of CIBLIN genes are unnamed genes in Drosophila, suggesting that there are many understudied genes. Interestingly, CIBLIN genes include many Myc synthetic lethal (MycSL) hits from recent screens. CIBLIN genes include key regulators of heparan sulfate proteoglycan (HSPG) sulfation patterns, and lysyl oxidases involved in cross-linking and modification of the extracellular matrix (ECM). These genes and others suggest the CIBLIN repertoire services critical functions in ECM remodeling and cell migration in large-bodied bilaterians. Correspondingly, CIBLIN genes are co-expressed with Myc in cancer transcriptomes, and include a preponderance of known determinants of cancer progression and tumor aggression. We propose that CIBLIN gene research can improve our understanding of regulatory control of cellular growth in metazoans.

  9. Impact of SNPs on CpG Islands in the MYC and HRAS oncogenes and in a wide variety of tumor suppressor genes: A multi-cancer approach

    PubMed Central

    Samy, Mohammad D.; Yavorski, John M.; Mauro, James A.; Blanck, George

    2016-01-01

    ABSTRACT Single nucleotide polymorphisms (SNPs) that occur within CpG Islands may lead to increased hypermethylation if a SNP allele has the potential to form a CpG dinucleotide, as well as potentially lead to hypomethylation if a SNP allele eliminates a CpG dinucleotide. We analyzed CpG-related SNP allele frequencies in whole genome sequences (WGS) across 5 TCGA cancer datasets, thereby exploiting a more recent appreciation for signaling pathway degeneracy in cancer. The cancer data sets were analyzed for SNPs in CpG islands associated with the oncogenes, HRAS and MYC, and in the CpG islands associated with the tumor suppressor genes, APC, DCC, and RB1. We determined that one SNP allele (rs3824120) in a CpG island associated with MYC which eliminated a CpG was more common in the cancer datasets than in the 100Genomes databases (p < 0.01). For HRAS, 2 SNP alleles (rs112690925, rs7939028) that created CpG's occurred significantly less frequently in the cancer data sets than in the general SNP databases (e.g., rs7939028, p < 0.0002, in comparison with AllSNPs(142)). Also, one SNP allele (rs4940177) that created a CpG in a CpG island associated with the DCC tumor suppressor gene, was more common in the cancer datasets (p < 0.0007). To understand a broader picture of the potential of SNP alleles to create CpG's in CpG islands of tumor suppressor genes, we developed a scripted algorithm to assess the SNP alleles associated with the CpG islands of 43 tumor suppressor genes. The following tumor suppressor genes have the possibility of significant, percent increases in their CpG counts, depending on which SNP allele(s) is present: VHL, BRCA1, BRCA2, CHEK2, PTEN and RB1. PMID:27074591

  10. Impact of SNPs on CpG Islands in the MYC and HRAS oncogenes and in a wide variety of tumor suppressor genes: A multi-cancer approach.

    PubMed

    Samy, Mohammad D; Yavorski, John M; Mauro, James A; Blanck, George

    2016-06-17

    Single nucleotide polymorphisms (SNPs) that occur within CpG Islands may lead to increased hypermethylation if a SNP allele has the potential to form a CpG dinucleotide, as well as potentially lead to hypomethylation if a SNP allele eliminates a CpG dinucleotide. We analyzed CpG-related SNP allele frequencies in whole genome sequences (WGS) across 5 TCGA cancer datasets, thereby exploiting a more recent appreciation for signaling pathway degeneracy in cancer. The cancer data sets were analyzed for SNPs in CpG islands associated with the oncogenes, HRAS and MYC, and in the CpG islands associated with the tumor suppressor genes, APC, DCC, and RB1. We determined that one SNP allele (rs3824120) in a CpG island associated with MYC which eliminated a CpG was more common in the cancer datasets than in the 100Genomes databases (p < 0.01). For HRAS, 2 SNP alleles (rs112690925, rs7939028) that created CpG's occurred significantly less frequently in the cancer data sets than in the general SNP databases (e.g., rs7939028, p < 0.0002, in comparison with AllSNPs(142)). Also, one SNP allele (rs4940177) that created a CpG in a CpG island associated with the DCC tumor suppressor gene, was more common in the cancer datasets (p < 0.0007). To understand a broader picture of the potential of SNP alleles to create CpG's in CpG islands of tumor suppressor genes, we developed a scripted algorithm to assess the SNP alleles associated with the CpG islands of 43 tumor suppressor genes. The following tumor suppressor genes have the possibility of significant, percent increases in their CpG counts, depending on which SNP allele(s) is present: VHL, BRCA1, BRCA2, CHEK2, PTEN and RB1.

  11. Negative autoregulation of c-myc transcription.

    PubMed Central

    Penn, L J; Brooks, M W; Laufer, E M; Land, H

    1990-01-01

    The introduction of activated c-myc and v-myc genes into a variety of non-established and established cells results in the suppression of endogenous c-myc expression. As measured in Rat-1 fibroblasts, the suppression occurs at the level of transcriptional initiation. Moreover, the extent of the down-regulation is proportional to the cellular concentration of c-myc protein, and the critical concentration range in which the endogenous c-myc RNA is effectively suppressed corresponds to that found in non-transformed cells. In addition, the autoregulatory mechanism is not only dependent on c-myc protein, but also requires additional trans-acting factors. These results support a role for c-myc in the regulation of cellular gene transcription and suggest that a negative feedback mechanism can act as a homeostatic regulator of c-myc expression in vivo. Images Fig. 1. Fig. 2. Fig. 4. Fig. 5. PMID:2182320

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

    PubMed

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

    2017-04-11

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

  13. 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

  14. The metastasis suppressor, N-myc downstream regulated gene 1 (NDRG1), upregulates p21 via p53-independent mechanisms.

    PubMed

    Kovacevic, Zaklina; Sivagurunathan, Sutharshani; Mangs, Helena; Chikhani, Sherin; Zhang, Daohai; Richardson, Des R

    2011-05-01

    The metastasis suppressor, N-myc downstream regulated gene-1 (NDRG1), has been shown to markedly reduce metastasis of numerous tumors. The current study was focused on further elucidating the molecular mechanisms behind the antitumor function of NDRG1. We have identified for the first time that NDRG1 upregulates the potent cyclin-dependent kinase inhibitor, p21. This effect was observed in three different cancer cell types, including PC3MM and DU145 prostate cancer cells and H1299 lung carcinoma cells, and occurred independently of p53. In addition, reducing NDRG1 expression using short hairpin RNA in PC3MM and DU145 cells resulted in significantly reduced p21 protein levels. Hence, p21 is closely correlated with NDRG1 expression in these latter cell types. Examining the mechanisms behind the effect of NDRG1 on p21 expression, we found that NDRG1 upregulated p21 via transcriptional and posttranscriptional mechanisms in prostate cancer cells, although its effect on H1299 cells was posttranscriptional only. Further studies identified two additional NDRG1 protein targets. The dominant-negative p63 isoform, ΔNp63, which has been found to inhibit p21 transcription, was downregulated by NDRG1. On the other hand, a truncated 50 kDa MDM2 isoform (p50(MDM2)), which may protect p21 from proteasomal degradation, was upregulated by NDRG1. The downregulation of ΔNp63 and upregulation of p50(MDM2) are potential mechanisms by which NDRG1 increases p21 expression in these cells. Additional functional studies identified that NDRG1 inhibits cancer cell migration, suggesting that p21 is a molecular player in its antimetastatic activity.

  15. Long-term cultivation of in vitro Apis mellifera cells by gene transfer of human c-myc proto-oncogene.

    PubMed

    Kitagishi, Yasuko; Okumura, Naoko; Yoshida, Hitomi; Nishimura, Yuri; Takahashi, Jun-ichi; Matsuda, Satoru

    2011-08-01

    Establishment of cell lines representative of honeybee character would greatly assist in their analysis. Here, we show that immortalized cell line, designated as MYN9, has been generated from honeybee embryo by the gene transfer of human c-myc proto-oncogene. The morphology of the cell is characteristic of embryonic stem cell, although the cell is stable and does not spontaneously differentiate. Polymerase chain reaction analyses show that the cell is originated from authentic honeybee cell. It is proposed that the integration of human c-myc gene into honeybee precursor populations results in the establishment of stable cell line suitable for cellular and molecular studies.

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

    PubMed

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

    2011-08-01

    To detect the expression of c-myc in the tissue of laryngeal squamous cell carcinoma. RNA interference(RNAi) was employed to inhibit the expression of c-myc in Hep-2 cells and to evaluate the effects of c-myc as a target for gene therapy in laryngeal carcinoma. Immunohistochemistry was used to determine the protein levels of c-myc and Rb in 80 cases of laryngeal squamous cell carcinoma and 30 cases of polyp of vocal cord. Hep-2 cells were transfected with c-myc siRNA, c-myc protein and mRNA levels were detected using Western Blotting and RT-PCR. Cell viability was detected by MTT after the Hep-2 cells were transfected with c-myc siRNA for different times or transfected with different concentrations c-myc siRNA. The sensitivity of Hep-2 cells to 5-Fu transfected with or without c-myc siRNA was evaluated also by MTT. Hep-2 cells were transfected with c-myc siRNA in combination with 5-Fu for 48 h and then analyzed cell apoptosis by flow cytometry. Immunohistochemical analysis showed that c-myc was highly expressed in the tissues of laryngeal squamous cell carcinoma while the expression of Rb was lower. The protein and mRNA levels of c-myc decreased after transfected with c-myc siRNA. The results of MTT showed that the c-myc siRNA inhibited Hep-2 cells growth in a concentration-dependent manner. When transfected with c-myc siRNA(50 nmol/L), the cells were inhibited in a time-dependent manner. Compared with the untransfected cells, the viability of transfected Hep-2 cells was significantly suppressed at the same concentration of 5-Fu (P < 0.05). C-myc siRNA combination with 5-Fu could obviously increase cell apoptosis, even in the low concentration of 5-Fu (P < 0.05). The protein level of C-myc has highly expressed in tumor tissues. C-myc siRNA can effectively inhibit the expression of c-myc and has anti-proliferation effects, increasing the sensitivity of Hep-2 cells to 5-Fu. Therefore,c-myc might be a good target for cancer treatment.

  17. RUNX3 is oncogenic in natural killer/T-cell lymphoma and is transcriptionally regulated by MYC.

    PubMed

    Selvarajan, V; Osato, M; Nah, G S S; Yan, J; Chung, T-H; Voon, D C-C; Ito, Y; Ham, M F; Salto-Tellez, M; Shimizu, N; Choo, S-N; Fan, S; Chng, W-J; Ng, S-B

    2017-02-17

    RUNX3, runt-domain transcription factor, is a master regulator of gene expression in major developmental pathways. It acts as a tumor suppressor in many cancers but is oncogenic in certain tumors. We observed upregulation of RUNX3 mRNA and protein expression in nasal-type extranodal natural killer (NK)/T-cell lymphoma (NKTL) patient samples and NKTL cell lines compared to normal NK cells. RUNX3 silenced NKTL cells showed increased apoptosis and reduced cell proliferation. Potential binding sites for MYC were identified in the RUNX3 enhancer region. Chromatin immunoprecipitation-quantitative PCR revealed binding activity between MYC and RUNX3. Co-transfection of the MYC expression vector with RUNX3 enhancer reporter plasmid resulted in activation of RUNX3 enhancer indicating that MYC positively regulates RUNX3 transcription in NKTL cell lines. Treatment with a small-molecule MYC inhibitor (JQ1) caused significant downregulation of MYC and RUNX3, leading to apoptosis in NKTL cells. The growth inhibition resulting from depletion of MYC by JQ1 was rescued by ectopic MYC expression. In summary, our study identified RUNX3 overexpression in NKTL with functional oncogenic properties. We further delineate that MYC may be an important upstream driver of RUNX3 upregulation and since MYC is upregulated in NKTL, further study on the employment of MYC inhibition as a therapeutic strategy is warranted.Leukemia advance online publication, 17 February 2017; doi:10.1038/leu.2017.40.

  18. Relationship of Amplification and Expression of the C-MYC Gene with Survival among Gastric Cancer Patients.

    PubMed

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

    2015-01-01

    During the past decades, the incidence and mortality rate of stomach cancer has demonstrated a great decrease in the world, but it is still one of the most common and fatal cancers especially among men worldwide, including Iran. The MYC proto-oncogene, which is located at 8q24.1, regulates 15% of genes and is activated in 20% of all human tumors. MYC amplification and overexpression of its protein product has been reported in 15-30% of gastric neoplasias. The aim of this investigation was to find the relative efficacy of CISH (chromogenic in situ hybridization) or IHC (immunohistochemistry) in diagnosis and prognosis of gastric cancer, as well as the relationship of amplification and expression of C-MYC gene with patient survival. In this cross-sectional study, 102 samples of gastric cancer were collected from patients who had undergone primary surgical resection at the Cancer Institute Hospital, Tehran University of Medical Sciences, from July 2009 to March 2014. All samples were randomly selected from those who were diagnosed with gastric adenocarcinomas. CISH and IHC methods were performed on all of them. Patients were classified into two groups. The first consisted of stage I and II cases, and the second of stage III and IV. Survival tests for both groups was carried out with referrnce to CISH test reults. Group II (stage III and IV) with CISH+ featured lower survival than those with CISH- (p=0.233), but group I (stage I and II) patients demonstrated no significant variation with CISH+ or CISH- (p=0.630). Kaplan-Meier for both groups was carried out with IHC test findings and showed similar results. This data revealed that both diffuse and intestinal types of gastric cancer occurred significantly more in men than women. Our data also showed that CISH+ patients (43%) were more frequent in comparison with IHC+ patients (14.7%). For planning treatment of gastric cancer patients, by focusing on expanding tumors, which is the greatest concern of the surgeons and

  19. ECA39, a conserved gene regulated by c-Myc in mice, is involved in G1/S cell cycle regulation in yeast.

    PubMed Central

    Schuldiner, O; Eden, A; Ben-Yosef, T; Yanuka, O; Simchen, G; Benvenisty, N

    1996-01-01

    The c-myc oncogene has been shown to play a role in cell proliferation and apoptosis. The realization that myc oncogenes may control the level of expression of other genes has opened the field to search for genetic targets for Myc regulation. Recently, using a subtraction/coexpression strategy, a murine genetic target for Myc regulation, called EC439, was isolated. To further characterize the ECA39 gene, we set out to determine the evolutionary conservation of its regulatory and coding sequences. We describe the human, nematode, and budding yeast homologs of the mouse ECA39 gene. Identities between the mouse ECA39 protein and the human, nematode, or yeast proteins are 79%, 52%, and 49%, respectively. Interestingly, the recognition site for Myc binding, located 3' to the start site of transcription in the mouse gene, is also conserved in the human homolog. This regulatory element is missing in the ECA39 homologs from nematode or yeast, which also lack the regulator c-myc. To understand the function of ECA39, we deleted the gene from the yeast genome. Disruption of ECA39 which is a recessive mutation that leads to a marked alteration in the cell cycle. Mutant haploids and homozygous diploids have a faster growth rate than isogenic wild-type strains. Fluorescence-activated cell sorter analyses indicate that the mutation shortens the G1 stage in the cell cycle. Moreover, mutant strains show higher rates of UV-induced mutations. The results suggest that the product of ECA39 is involved in the regulation of G1 to S transition. Images Fig. 2 Fig. 3 Fig. 5 PMID:8692959

  20. Nfkb 1 is dispensable for Myc-induced lymphomagenesis.

    PubMed

    Keller, Ulrich; Nilsson, Jonas A; Maclean, Kirsteen H; Old, Jennifer B; Cleveland, John L

    2005-09-15

    Rel/NF-kappaB transcription factors are critical arbiters of immune responses, cell survival, and transformation, and are frequently deregulated in cancer. The p50 NF-kappaB 1 component of Rel/NF-kappaB DNA-binding dimers regulates genes involved in both cell cycle traverse and apoptosis. Nfkb 1 loss accelerates B cell growth and leads to increased B cell turnover in vivo, phenotypes akin to those manifested in B cells of Emu-Myc transgenic mice, a model of human Burkitt lymphoma. Interestingly, Emu-Myc B cells express reduced levels of cytoplasmic and nuclear NF-kappaB 1 and have reduced Rel/NF-kappaB DNA-binding activity, suggesting that Myc-mediated repression of NF-kappaB 1 might mediate its proliferative and apoptotic effects on B cells. Furthermore, Nfkb 1 expression was reduced in the majority of Emu-Myc lymphomas and was also suppressed in human Burkitt lymphoma. Nonetheless, loss of Nfkb 1 did not appreciably affect Myc's proliferative or apoptotic responses in B cells and had no effect on lymphoma development in Emu-Myc mice. Therefore, Nfkb 1 is dispensable for Myc-induced lymphomagenesis.. Oncogene (2005) 24, 6231-6240

  1. C-myc gene chromatin of estrogen receptor positive and negative breast cancer cells.

    PubMed

    Miller, T L; Huzel, N J; Davie, J R; Murphy, L C

    1993-02-01

    Expression of the c-myc protooncogene is estrogen regulated in estrogen receptor (ER) positive, hormone-dependent human breast cancer cells, but it is constitutively active in ER negative, hormone-independent breast cancer cells. To determine whether these differences are reflected in c-myc chromatin, DNase I hypersensitive sites (DHS) were mapped. Six DHS were detected in all cell lines studied, with DHS 3(2) being more prominent than DHS 3(1). The accessibility of DHS 2 was markedly greater in ER negative cells than in ER positive cells, and this relative accessibility remained unchanged when cells were grown in estrogen free medium. DHS 2, 3(1) and 3(2) map near the P0, P1 and P2 promoters, respectively. An analysis of promoter usage demonstrated that P2 was the preferred promoter. Thus, the differences in the accessibility of DHS 2 in c-myc chromatin of ER positive and negative cells likely reflects alterations in DNA-protein interactions in this region.

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

    PubMed

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

    2009-07-09

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

  3. MYC2, MYC3, and MYC4 function redundantly in seed storage protein accumulation in Arabidopsis.

    PubMed

    Gao, Chenhao; Qi, Shuanghui; Liu, Kaige; Li, Dong; Jin, Changyu; Li, Zhuowei; Huang, Gengqing; Hai, Jiangbo; Zhang, Meng; Chen, Mingxun

    2016-11-01

    Basic helix-loop-helix transcription factors (TFs), namely MYC2, MYC3, and MYC4, interact with Jasmonate Zim-domain proteins and are their direct targets. These TFs have been shown to function synergistically to control Arabidopsis growth and development. Our results showed similar MYC2, MYC3, and MYC4 expression patterns during Arabidopsis seed development, which remained relatively high during seed mid-maturation. MYC2, MYC3, and MYC4 acted redundantly in seed size, weight control, and in regulating seed storage protein accumulation. Triple mutants produced the largest seeds and single and double mutants' seeds were much larger than those of wild type. The weight of triple mutants' seeds was significantly higher than that of wild-type seeds, which was accompanied by an increase in seed storage protein contents. Triple mutants' seeds presented a marked decrease in 2S amounts relative to those in wild-type seeds. Liquid chromatography tandem mass spectra sequencing results indicated that both the relative abundance and the peptide number of CRA1 and CRU3 were greatly increased in triple mutants compared to wild type. The expression of 2S1-2S5 decreased and that of CRA1 and CRU3 increased in triple mutants relative to those in wild types during seed development, which might have contributed to the low 2S and high 12S contents in triple mutants. Our results contribute to understanding the function of MYC2, MYC3, and MYC4 on seed development, and provide promising targets for genetic manipulations of protein-producing crops to improve the quantity and quality of seed storage proteins. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

  4. Cloned origin of DNA replication in c-myc gene can function and be transmitted in transgenic mice in an episomal state.

    PubMed Central

    Sudo, K; Ogata, M; Sato, Y; Iguchi-Ariga, S M; Ariga, H

    1990-01-01

    The c-myc protein has recently been shown to interact with a region possessing putative origin of DNA replication and enhancer activities located 2 kb upstream of the c-myc gene itself. Transgenic mice were obtained by injecting constructs containing this region, termed pmyc(H-P), into fertilized mouse eggs. The transgenic elements were capable of efficient replication in all mouse tissues examined and were maintained in an episomal state even in highly differentiated cells. Moreover, pmyc(H-P) was transmittable to the progeny throughout several generations, which suggests that the fragment derived from the region upstream of the c-myc gene possesses sequences necessary for partition, stability and DNA replication of the plasmid in the cells. In addition, we have shown that the plasmid might be captured only by eggs, not by sperm. Images PMID:2216716

  5. MYC in Regulating Immunity: Metabolism and Beyond

    PubMed Central

    Gnanaprakasam, J.N. Rashida; Wang, Ruoning

    2017-01-01

    Myelocytomatosis oncogene (MYC) family members, including cellular MYC (c-Myc), neuroblastoma derived MYC (MYCN), and lung carcinoma derived MYC (MYCL), have all been implicated as key oncogenic drivers in a broad range of human cancers. Beyond cancer, MYC plays an important role in other physiological and pathological processes, namely immunity and immunological diseases. MYC largely functions as a transcription factor that promotes the expression of numerous target genes to coordinate death, proliferation, and metabolism at the cellular, tissue, and organismal levels. It has been shown that the expression of MYC family members is tightly regulated in immune cells during development or upon immune stimulations. Emerging evidence suggests that MYC family members play essential roles in regulating the development, differentiation and activation of immune cells. Through driving the expression of a broad range of metabolic genes in immune cells, MYC family members coordinate metabolic programs to support immune functions. Here, we discuss our understanding of MYC biology in immune system and how modulation of MYC impacts immune metabolism and responses. PMID:28245597

  6. Specific inhibition of gene expression and transactivation functions of hepatitis B virus X protein and c-myc by small interfering RNAs.

    PubMed

    Hung, Le; Kumar, Vijay

    2004-02-27

    With a view to developing therapeutic strategies against hepatocellular carcinoma (HCC), we have recently shown that co-expression of c-myc and the X protein of hepatitis B virus (HBx) resulted in the development of HCC in the X-myc transgenic mice. We now show in cell culture-based studies that small interfering RNA (siRNA) corresponding to HBx and c-myc can regulate expression and transactivation of the target genes. Expression vectors for small hairpin RNAs (shRNAs) against two different regions each of the HBx and c-myc open reading frames were constructed and their regulatory effects were investigated in COS-1 cells. A dose-dependent specific inhibition in the expression levels of HBx and c-myc was observed with individual shRNAs. Further, the recombinantly expressed shRNAs also blocked the transactivation functions of their cognate genes. Though each shRNA worked at a different efficiency, the inhibitory effects with two different shRNAs were cumulative. These results appear promising for developing a siRNA-based therapy for HCC.

  7. Cell cycle regulation of the c-Myc transcriptional activation domain.

    PubMed Central

    Seth, A; Gupta, S; Davis, R J

    1993-01-01

    The product of the c-myc gene (c-Myc) is a sequence-specific DNA-binding protein that has previously been demonstrated to be required for cell cycle progression. Here we report that the c-Myc DNA binding site confers cell cycle regulation to a reporter gene in Chinese hamster ovary cells. The observed transactivation was biphasic with a small increase in G1 and a marked increase during the S-to-G2/M transition of the cell cycle. This cell cycle regulation of transactivation potential is accounted for, in part, by regulatory phosphorylation of the c-Myc transactivation domain. Together, these data demonstrate that c-Myc may have an important role in the progression of cells through both the G1 and G2 phases of the cell cycle. Images PMID:8321217

  8. A MYC-Driven Change in Mitochondrial Dynamics Limits YAP/TAZ Function in Mammary Epithelial Cells and Breast Cancer.

    PubMed

    von Eyss, Björn; Jaenicke, Laura A; Kortlever, Roderik M; Royla, Nadine; Wiese, Katrin E; Letschert, Sebastian; McDuffus, Leigh-Anne; Sauer, Markus; Rosenwald, Andreas; Evan, Gerard I; Kempa, Stefan; Eilers, Martin

    2015-12-14

    In several developmental lineages, an increase in MYC expression drives the transition from quiescent stem cells to transit-amplifying cells. We show that MYC activates a stereotypic transcriptional program of genes involved in cell growth in mammary epithelial cells. This change in gene expression indirectly inhibits the YAP/TAZ co-activators, which maintain the clonogenic potential of these cells. We identify a phospholipase of the mitochondrial outer membrane, PLD6, as the mediator of MYC activity. MYC-dependent growth strains cellular energy resources and stimulates AMP-activated kinase (AMPK). PLD6 alters mitochondrial fusion and fission dynamics downstream of MYC. This change activates AMPK, which in turn inhibits YAP/TAZ. Mouse models and human pathological data show that MYC enhances AMPK and suppresses YAP/TAZ activity in mammary tumors.

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

    PubMed

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

    2015-04-01

    Leukemias expressing the constitutively activated tyrosine kinases (TK) BCR-ABL1 and FLT3/ITD activate signaling pathways that increase genomic instability through generation of reactive oxygen species (ROS), DNA double-strand breaks (DSB), and error-prone repair. The nonhomologous end-joining (NHEJ) pathway is a major pathway for DSB repair and is highly aberrant in TK-activated leukemias; an alternative form of NHEJ (ALT-NHEJ) predominates, evidenced by increased expression of DNA ligase IIIα (LIG3) and PARP1, increased frequency of large genomic deletions, and repair using DNA sequence microhomologies. This study, for the first time, demonstrates that the TK target c-MYC plays a role in transcriptional activation and subsequent expression of LIG3 and PARP1 and contributes to the increased error-prone repair observed in TK-activated leukemias. c-MYC negatively regulates microRNAs miR-150 and miR-22, which demonstrate an inverse correlation with LIG3 and PARP1 expression in primary and cultured leukemia cells and chronic myelogenous leukemia human patient samples. Notably, inhibition of c-MYC and overexpression of miR-150 and -22 decreases ALT-NHEJ activity. Thus, BCR-ABL1 or FLT3/ITD induces c-MYC expression, leading to genomic instability via augmented expression of ALT-NHEJ repair factors that generate repair errors. In the context of TK-activated leukemias, c-MYC contributes to aberrant DNA repair through downstream targets LIG3 and PARP1, which represent viable and attractive therapeutic targets. ©2015 American Association for Cancer Research.

  10. 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.

  11. c-Myc Alters Substrate Utilization and O-GlcNAc Protein Posttranslational Modifications without Altering Cardiac Function during Early Aortic Constriction

    PubMed Central

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

    2015-01-01

    Hypertrophic stimuli cause transcription of the proto-oncogene c-Myc (Myc). Prior work showed that myocardial knockout of c-Myc (Myc) attenuated hypertrophy and decreased expression of metabolic genes after aortic constriction. Accordingly, we assessed the interplay between Myc, substrate oxidation and cardiac function during early pressure overload hypertrophy. Mice with cardiac specific, inducible Myc knockout (MycKO-TAC) and non-transgenic littermates (Cont-TAC) were subjected to transverse aortic constriction (TAC; n = 7/group). Additional groups underwent sham surgery (Cont-Sham and MycKO-Sham, n = 5 per group). 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. In sham hearts, Myc knockout did not affect cardiac function or substrate preferences for the citric acid cycle. However, Myc knockout altered fractional contributions during TAC. The unlabeled fractional contribution increased in MycKO-TAC versus Cont-TAC, whereas ketone and free fatty acid fractional contributions decreased. Additionally, protein posttranslational modifications by O-GlcNAc were significantly greater in Cont-TAC versus both Cont-Sham and MycKO-TAC. In conclusion, 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, which may regulate Myc-induced metabolic changes. PMID:26266538

  12. Drosophila Growth and Development in the Absence of dMyc and dMnt

    PubMed Central

    Pierce, Sarah B.; Yost, Cynthia; Anderson, Sarah A. R.; Flynn, Erin M.; Delrow, Jeffrey; Eisenman, Robert N.

    2008-01-01

    Myc oncoproteins are essential regulators of the growth and proliferation of mammalian cells. In Drosophila the single ortholog of Myc (dMyc), encoded by the dm gene, influences organismal size and the growth of both mitotic and endoreplicating cells. A null mutation in dm results in attenuated endoreplication and growth arrest early in larval development. Drosophila also contains a single ortholog of the mammalian Mad/Mnt transcriptional repressor proteins (dMnt), which is thought to antagonize dMyc function. Here we show that animals lacking both dMyc and dMnt display increased viability and grow significantly larger and develop further than dMyc single mutants. We observe increased endoreplication and growth of larval tissues in these double mutants and disproportionate growth of the imaginal discs. Gene expression analysis indicates that loss of dMyc leads to decreased expression of genes required for ribosome biogenesis and protein synthesis. The additional loss of dMnt partially rescues expression of a small number of dMyc and dMnt genes that are primarily involved in rRNA synthesis and processing. Our results indicate that dMnt repression is normally overridden by dMyc activation during larval development. Therefore the severity of the dm null phenotype is likely due to unopposed repression by dMnt on a subset of genes critical for cell and organismal growth. Surprisingly, considerable growth and development can occur in the absence of both dMyc and dMnt. PMID:18241851

  13. 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

    2016-06-30

    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.

  14. Haploinsufficiency of the Myc regulator Mtbp extends survival and delays tumor development in aging mice

    PubMed Central

    Grieb, Brian C.; Boyd, Kelli; Mitra, Ramkrishna; Eischen, Christine M.

    2016-01-01

    Alterations of specific genes can modulate aging. Myc, a transcription factor that regulates the expression of many genes involved in critical cellular functions was shown to have a role in controlling longevity. Decreased expression of Myc inhibited many of the deleterious effects of aging and increased lifespan in mice. Without altering Myc expression, reduced levels of Mtbp, a recently identified regulator of Myc, limit Myc transcriptional activity and proliferation, while increased levels promote Myc-mediated effects. To determine the contribution of Mtbp to the effects of Myc on aging, we studied a large cohort of Mtbp heterozygous mice and littermate matched wild-type controls. Mtbp haploinsufficiency significantly increased longevity and maximal survival in mice. Reduced levels of Mtbp did not alter locomotor activity, litter size, or body size, but Mtbp heterozygous mice did exhibit elevated markers of metabolism, particularly in the liver. Mtbp+/− mice also had a significant delay in spontaneous cancer development, which was most prominent in the hematopoietic system, and an altered tumor spectrum compared to Mtbp+/+ mice. Therefore, the data suggest Mtbp is a regulator of longevity in mice that mimics some, but not all, of the properties of Myc in aging. PMID:27803394

  15. Myc/Mycn-mediated glycolysis enhances mouse spermatogonial stem cell self-renewal.

    PubMed

    Kanatsu-Shinohara, Mito; Tanaka, Takashi; Ogonuki, Narumi; Ogura, Atsuo; Morimoto, Hiroko; Cheng, Pei Feng; Eisenman, Robert N; Trumpp, Andreas; Shinohara, Takashi

    2016-12-01

    Myc plays critical roles in the self-renewal division of various stem cell types. In spermatogonial stem cells (SSCs), Myc controls SSC fate decisions because Myc overexpression induces enhanced self-renewal division, while depletion of Max, a Myc-binding partner, leads to meiotic induction. However, the mechanism by which Myc acts on SSC fate is unclear. Here we demonstrate a critical link between Myc/Mycn gene activity and glycolysis in SSC self-renewal. In SSCs, Myc/Mycn are regulated by Foxo1, whose deficiency impairs SSC self-renewal. Myc/Mycn-deficient SSCs not only undergo limited self-renewal division but also display diminished glycolytic activity. While inhibition of glycolysis decreased SSC activity, chemical stimulation of glycolysis or transfection of active Akt1 or Pdpk1 (phosphoinositide-dependent protein kinase 1 ) augmented self-renewal division, and long-term SSC cultures were derived from a nonpermissive strain that showed limited self-renewal division. These results suggested that Myc-mediated glycolysis is an important factor that increases the frequency of SSC self-renewal division. © 2016 Kanatsu-Shinohara et al.; Published by Cold Spring Harbor Laboratory Press.

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

    PubMed

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

    2015-09-01

    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.

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

    PubMed

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

    2014-02-01

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

  18. MYC — EDRN Public Portal

    Cancer.gov

    The oncogenic protein MYC, previously known as c-MYC, is a multifunctional, nuclear phosphoprotein that plays a role in cell cycle progression, apoptosis and cellular transformation. It participates in the regulation of gene transcription of specific target genes. MYC binds DNA in a non-specific manner, yet also specifically recognizes the core sequence 5'-CAC[GA]TG-3'. Mutations, overexpression, rearrangement and translocation of the MYC gene have been associated with a variety of hematopoietic tumors, leukemias and lymphomas, including Burkitt lymphoma. Evidence shows that alternative translation initiations from an upstream, in-frame non-AUG (CUG) and a downstream AUG start site result in the production of two isoforms with distinct N-termini.

  19. Integrative analysis of RNA polymerase II and transcriptional dynamics upon MYC activation.

    PubMed

    de Pretis, Stefano; Kress, Theresia R; Morelli, Marco J; Sabò, Arianna; Locarno, Chiara; Verrecchia, Alessandro; Doni, Mirko; Campaner, Stefano; Amati, Bruno; Pelizzola, Mattia

    2017-10-01

    Overexpression of the MYC transcription factor causes its widespread interaction with regulatory elements in the genome but leads to the up- and down-regulation of discrete sets of genes. The molecular determinants of these selective transcriptional responses remain elusive. Here, we present an integrated time-course analysis of transcription and mRNA dynamics following MYC activation in proliferating mouse fibroblasts, based on chromatin immunoprecipitation, metabolic labeling of newly synthesized RNA, extensive sequencing, and mathematical modeling. Transcriptional activation correlated with the highest increases in MYC binding at promoters. Repression followed a reciprocal scenario, with the lowest gains in MYC binding. Altogether, the relative abundance (henceforth, "share") of MYC at promoters was the strongest predictor of transcriptional responses in diverse cell types, predominating over MYC's association with the corepressor ZBTB17 (also known as MIZ1). MYC activation elicited immediate loading of RNA polymerase II (RNAPII) at activated promoters, followed by increases in pause-release, while repressed promoters showed opposite effects. Gains and losses in RNAPII loading were proportional to the changes in the MYC share, suggesting that repression by MYC may be partly indirect, owing to competition for limiting amounts of RNAPII. Secondary to the changes in RNAPII loading, the dynamics of elongation and pre-mRNA processing were also rapidly altered at MYC regulated genes, leading to the transient accumulation of partially or aberrantly processed mRNAs. Altogether, our results shed light on how overexpressed MYC alters the various phases of the RNAPII cycle and the resulting transcriptional response. © 2017 de Pretis et al.; Published by Cold Spring Harbor Laboratory Press.

  20. c-Myc enhances protein synthesis and cell size during B lymphocyte development

    PubMed Central

    Iritani, Brian M.; Eisenman, Robert N.

    1999-01-01

    Members of the myc family of nuclear protooncogenes play roles in cell proliferation, differentiation, and apoptosis. Moreover, inappropriate expression of c-myc genes contributes to the development of many types of cancers, including B cell lymphomas in humans. Although Myc proteins have been shown to function as transcription factors, their immediate effects on the cell have not been well defined. Here we have utilized a murine model of lymphomagenesis (Eμ-myc mice) to show that constitutive expression of a c-myc transgene under control of the Ig heavy-chain enhancer (Eμ) results in an increase in cell size of normal pretransformed B lymphocytes at all stages of B cell development. Furthermore, we show that c-Myc-induced growth occurs independently of cell cycle phase and correlates with an increase in protein synthesis. These results suggest that Myc may normally function by coordinating expression of growth-related genes in response to mitogenic signals. Deregulated c-myc expression may predispose to cancer by enhancing cell growth to levels required for unrestrained cell division. PMID:10557294

  1. A gene expression signature from human breast cancer cells with acquired hormone independence identifies MYC as a mediator of antiestrogen resistance

    PubMed Central

    Miller, Todd W.; Balko, Justin M.; Ghazoui, Zara; Dunbier, Anita; Anderson, Helen; Dowsett, Mitch; González-Angulo, Ana M.; Mills, Gordon B.; Miller, William R.; Wu, Huiyun; Shyr, Yu; Arteaga, Carlos L.

    2011-01-01

    Purpose Although most patients with estrogen receptor α (ER)-positive breast cancer initially respond to endocrine therapy, many ultimately develop resistance to antiestrogens. However, mechanisms of antiestrogen resistance and biomarkers predictive of such resistance are underdeveloped. Experimental Design We adapted four ER+ human breast cancer cell lines to grow in an estrogen-depleted medium. A gene signature of estrogen independence was developed by comparing expression profiles of long-term estrogen-deprived (LTED) cells to their parental counterparts. We evaluated the ability of the LTED signature to predict tumor response to neoadjuvant therapy with an aromatase inhibitor, and disease outcome following adjuvant tamoxifen. We utilized Gene Set Analysis (GSA) of LTED cell gene expression profiles and a loss-of-function approach to identify pathways causally associated with resistance to endocrine therapy. Results The LTED gene expression signature was predictive of high tumor cell proliferation following neoadjuvant therapy with anastrozole and letrozole, each in different patient cohorts. This signature was also predictive of poor recurrence-free survival in two studies of patients treated with adjuvant tamoxifen. Bioinformatic interrogation of expression profiles in LTED cells revealed a signature of MYC activation. The MYC activation signature and high MYC protein levels were both predictive of poor outcome following tamoxifen therapy. Finally, knockdown of MYC inhibited LTED cell growth. Conclusions A gene expression signature derived from ER+ breast cancer cells with acquired hormone independence predicted tumor response to aromatase inhibitors and associated with clinical markers of resistance to tamoxifen. In some cases, activation of the MYC pathway was associated with this resistance. PMID:21346144

  2. Simultaneous detection of human papillomavirus integration and c-MYC gene amplification in cervical lesions: an emerging marker for the risk to progression.

    PubMed

    Gimenes, Fabrícia; Souza, Raquel Pantarotto; de Abreu, André Luelsdorf Pimenta; Pereira, Monalisa Wolski; Consolaro, Marcia Edilaine Lopes; da Silva, Vânia Ramos Sela

    2016-04-01

    The persistence of high-risk oncogenic human papillomavirus (HR-HPV) infection and its integration into the host genome are key steps in the induction of malignant alterations. c-MYC chromosome region is a frequent localization for HPV insertion that has been observed in chromosome band 8q24 by fluorescence in situ hybridization (FISH). We report the HPV viral integration and amplification patterns of the c-MYC gene in cytological smears with FISH as a potential biomarker for the progression of squamous intraepithelial lesions (SIL). HPV detection and genotyping by polymerase chain reaction (PCR) and FISH analysis by "Vysis Cervical FISH Probe" kit (ABBOTT Molecular Inc.) were performed in 37 cervical samples including 8 NILM, 7 ASC-US, 7 LSIL, 3 ASC-H, 7 HSIL and 5 SCC. The results show concordance between FISH and PCR techniques for HPV detection. The majority of the samples contained HR-HPV, the majority being -16 and -18 genotypes. HPV integration as determined by FISH was most frequent in high-risk lesions. The c-MYC gene amplification was found only in HPV-positive samples and was detected primarily in high-risk lesions and in cells with an integrated form of HPV. HPV integration and c-MYC gene amplification detected by FISH could be an important biomarker for use in clinical practice to determine SIL with a risk of progression.

  3. 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.

  4. Myc-interacting protein 1 target gene profile: A link to microtubules, extracellular signal-regulated kinase, and cell growth

    PubMed Central

    Ziegelbauer, Joseph; Wei, Joyce; Tjian, Robert

    2004-01-01

    To study the role of the transcription factor Myc-interacting protein 1 (MIZ-1) in activating various target genes after induction with the microtubule disrupting agent T113242, we have used small interfering RNA duplexes (siRNAs) to knockdown the expression of MIZ-1. As expected, depletion of MIZ-1 resulted in the inhibition of T113242-dependent activation of the low-density lipoprotein receptor (LDLR) gene in hepatocytes. Cells transfected with MIZ-1 siRNAs also exhibited growth arrest. In addition, inhibition of the extracellular signal-regulated kinase (ERK) pathway inhibited T113242-induced nuclear accumulation of MIZ-1 and activation of LDLR. Gene expression microarray analysis under various induction conditions identified other T113242-activated genes affected by a decrease in MIZ-1 and inhibition of the ERK pathway. We also found that the accumulation of MIZ-1 in the nucleus is influenced by cell–cell contact and/or growth. Taken together, our studies suggest that MIZ-1 regulates a specific set of genes that includes LDLR and that the ERK pathway plays a role in the activation of target promoters by MIZ-1. PMID:14704274

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

    PubMed

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

    2004-06-25

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

  6. 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

  7. N-myc downstream regulated gene 1 (NDRG1) promotes metastasis of human scirrhous gastric cancer cells through epithelial mesenchymal transition.

    PubMed

    Ureshino, Hiroki; Murakami, Yuichi; Watari, Kosuke; Izumi, Hiroto; Kawahara, Akihiko; Kage, Masayoshi; Arao, Tokuzo; Nishio, Kazuto; Yanagihara, Kazuyoshi; Kinoshita, Hisafumi; Kuwano, Michihiko; Ono, Mayumi

    2012-01-01

    Our recent study demonstrated that higher expression of N-myc downregulated gene 1 (NDRG1) is closely correlated with poor prognosis in gastric cancer patients. In this study, we asked whether NDRG1 has pivotal roles in malignant progression including metastasis of gastric cancer cells. By gene expression microarray analysis expression of NDRG1 showed the higher increase among a total of 3691 up-regulated genes in a highly metastatic gastric cancer cell line (58As1) than their parental low metastatic counterpart (HSC-58). The highly metastatic cell lines showed decreased expression of E-cadherin, together with enhanced expression of vimentin and Snail. This decreased expression of E-cadherin was restored by Snail knockdown in highly metastatic cell lines. We next established stable NDRG1 knockdown cell lines (As1/Sic50 and As1/Sic54) from the highly metastatic cell line, and both of these cell lines showed enhanced expression of E-cadherin and decreased expression of vimentin and Snail. And also, E-cadherin promoter-driven luciferase activity was found to be increased by NDRG1 knockdown in the highly metastatic cell line. NDRG1 knockdown in gastric cancer cell showed suppressed invasion of cancer cells into surround tissues, suppressed metastasis to the peritoneum and decreased ascites accumulation in mice with significantly improved survival rates. This is the first study to demonstrate that NDRG1 plays its pivotal role in the malignant progression of gastric cancer through epithelial mesenchymal transition.

  8. MYC-driven inhibition of the glutamate-cysteine ligase promotes glutathione depletion in liver cancer.

    PubMed

    Anderton, Brittany; Camarda, Roman; Balakrishnan, Sanjeev; Balakrishnan, Asha; Kohnz, Rebecca A; Lim, Lionel; Evason, Kimberley J; Momcilovic, Olga; Kruttwig, Klaus; Huang, Qiang; Xu, Guowang; Nomura, Daniel K; Goga, Andrei

    2017-04-01

    How MYC reprograms metabolism in primary tumors remains poorly understood. Using integrated gene expression and metabolite profiling, we identify six pathways that are coordinately deregulated in primary MYC-driven liver tumors: glutathione metabolism; glycine, serine, and threonine metabolism; aminoacyl-tRNA biosynthesis; cysteine and methionine metabolism; ABC transporters; and mineral absorption. We then focus our attention on glutathione (GSH) and glutathione disulfide (GSSG), as they are markedly decreased in MYC-driven tumors. We find that fewer glutamine-derived carbons are incorporated into GSH in tumor tissue relative to non-tumor tissue. Expression of GCLC, the rate-limiting enzyme of GSH synthesis, is attenuated by the MYC-induced microRNA miR-18a. Inhibition of miR-18a in vivo leads to increased GCLC protein expression and GSH abundance in tumor tissue. Finally, MYC-driven liver tumors exhibit increased sensitivity to acute oxidative stress. In summary, MYC-dependent attenuation of GCLC by miR-18a contributes to GSH depletion in vivo, and low GSH corresponds with increased sensitivity to oxidative stress in tumors. Our results identify new metabolic pathways deregulated in primary MYC tumors and implicate a role for MYC in regulating a major antioxidant pathway downstream of glutamine.

  9. Chronic radiation exposure of neuroblastoma cells reduces nMYC copy number.

    PubMed

    Gnanamony, Manu; Antony, Reuben; Fernández, Karen S; Jaime, Libes; Lin, Julian; Joseph, Pushpa A; Gondi, Christopher S

    2017-09-01

    Neuroblastoma accounts for >15% of cancer-associated mortalities of children in the USA. Despite aggressive treatment regimens, the long-term survival for these children remains <40%. The identification of v-Myc avian myelocytomatosis viral oncogene neuroblastoma-derived homolog (nMYC) gene amplification during diagnosis is associated with poor prognosis in neuroblastoma. There are limited studies examining changes in nMYC copy numbers in response to therapy and its biological effect on cancer cells. The aim of the present study was to evaluate the effect of radiation on nMYC expression and amplification status in high-risk neuroblastoma. The effect of acute (5 Gy) and chronic (25 Gy) radiation on two nMYC-amplified cell lines, SK-N-BE (2) and NB-1691, was investigated. The results demonstrate that, following chronic but not acute radiation, the two cell lines regained their proliferation potential similar to the controls. This increased proliferation was characterized by loss of nMYC mRNA and protein expression. It was also revealed that nMYC loss was accompanied by nuclear localization of c-Myc. Using fluorescent in situ hybridization and quantitative polymerase chain reaction analysis, the results of the present study demonstrated that chronic radiation causes a severe loss of nMYC gene copy number. The present study is the first to provide experimental evidence that prolonged radiation therapy affects nMYC gene copy number in high-risk neuroblastoma but does not significantly improve the prognostic outlook.

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

    PubMed Central

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

    2015-01-01

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

  11. 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

  12. c-MYC-induced genomic instability.

    PubMed

    Kuzyk, Alexandra; Mai, Sabine

    2014-04-01

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

  13. Nuclear colocalization of cellular and viral myc proteins with HSP70 in myc-overexpressing cells.

    PubMed Central

    Koskinen, P J; Sistonen, L; Evan, G; Morimoto, R; Alitalo, K

    1991-01-01

    The c-myc oncogene and its viral counterpart v-myc encode phosphoproteins which have been located within cell nuclei, excluding nucleoli. We have expressed the c-myc gene under the simian virus 40 early promoter and studied the distribution of its protein product in transient expression assays in COS, HeLa, and 293 cells. We found three distinct patterns of c-myc immunofluorescence in the transfected cells: one-third of the c-myc-positive cells displayed a diffuse nuclear distribution, and in two-thirds of the cells the c-myc fluorescence was accumulated either in small amorphous or in large multilobed phase-dense nuclear structures. Unexpectedly, these structures also stained for the HSP70 heat shock protein in both heat-shocked and untreated cells. Our results indicate that both transient and stable overexpression of either the c-myc or v-myc protein induces translocation of the endogenous HSP70 protein from the cytoplasm to the nucleus, where it becomes sequestered in structures containing the myc protein. Interestingly, the closely related N-myc protein does not stimulate substantial nuclear expression of the HSP70 protein. Studies with chimeric myc proteins revealed that polypeptide sequences encoded by the second exon of c-myc are involved in colocalization with HSP70. Images PMID:1846202

  14. Investigating actinomycin D binding to G-quadruplex, i-motif and double-stranded DNA in 27-nt segment of c-MYC gene promoter.

    PubMed

    Niknezhad, Zhila; Hassani, Leila; Norouzi, Davood

    2016-01-01

    c-MYC DNA is an attractive target for drug design, especially for cancer chemotherapy. Around 90% of c-MYC transcription is controlled by NHE III1, whose 27-nt purine-rich strand has the ability to form G-quadruplex structure. In this investigation, interaction of ActD with 27-nt G-rich strand (G/c-MYC) and its equimolar mixture with the complementary sequence, (GC/c-MYC) as well as related C-rich oligonucleotide (C/c-MYC) was evaluated. Molecular dynamic simulations showed that phenoxazine and lactone rings of ActD come close to the outer G-tetrad nucleotides indicating that ActD binds through end-stacking to the quadruplex DNA. RMSD and RMSF revealed that fluctuation of the quadruplex DNA increases upon interaction with the drug. The results of spectrophotometry and spectrofluorometry indicated that ActD most probably binds to the c-MYC quadruplex and duplex DNA via end-stacking and intercalation, respectively and polarity of ActD environment decreases due to the interaction. It was also found that binding of ActD to the GC-rich DNA is stronger than the two other forms of DNA. Circular dichroism results showed that the type of the three forms of DNA structures doesn't change, but their compactness alters due to their interaction with ActD. Finally, it can be concluded that ActD binds differently to double stranded DNA, quadruplex DNA and i-motif. Copyright © 2015 Elsevier B.V. All rights reserved.

  15. Endothelin-1 enhances the expression of the androgen receptor via activation of the c-Myc pathway in prostate cancer cells

    PubMed Central

    Lee, June G; Zheng, Rong; McCafferty-Cepero, Jennifer M; Burnstein, Kerry L; Nanus, David M; Shen, Ruoqian

    2008-01-01

    Increasing evidence suggests that androgen independent prostate cancer maintains a functional androgen receptor (AR) pathway despite the low levels of circulating androgen following androgen withdrawal, the molecular mechanisms of which are not well defined yet. To address this question, we investigated the effects of ET-1 on AR expression. Western analysis and RT-PCR revealed that in the presence of ET-1, levels of AR significantly increased in a time- and dose- dependent manner in LNCaP cells. Pre-treatments with inhibitors of Src and Phosphoinositide Kinase 3 (PI-3K) suppressed ET-1-induced AR expression. As ET-1 was reported to cause a transient increase in c-Myc mRNA levels, we examined the involvement of c-Myc in ET-1-mediated AR expression. Transient transfection of c-Myc siRNA neutralized ET-1-induced AR expression, suggesting that AR induction by ET-1 is c-Myc dependent. AR can regulate the transcription of its own gene via a mechanism in which c-Myc plays a crucial role. Therefore, we assessed if ET-1-induced-c-Myc leads to the enhancement of AR transcription. Reporter gene assays using the previously identified AR gene enhancer containing a c-Myc binding site were conducted in LNCaP cells. We found that ET-1 induced reporter gene activity from the construct containing the wild type but not mutant c-Myc binding site. Chromatin immunoprecipitation assays confirmed that ET-1 increased interaction between c-Myc and c-Myc binding sites in AR enhancer, suggesting that ET-1-induced AR transcription occurs via c-Myc-mediated AR transcription. Together, these data support the notion that ET-1, via Src/PI-3K signaling, augments c-Myc expression leading to enhanced AR expression in prostate cancer. PMID:18623111

  16. Stress-induced cleavage of Myc promotes cancer cell survival

    PubMed Central

    Conacci-Sorrell, Maralice; Ngouenet, Celine; Anderson, Sarah; Brabletz, Thomas; Eisenman, Robert N.

    2014-01-01

    Evasion of apoptosis is critical in Myc-induced tumor progression. Here we report that cancer cells evade death under stress by activating calpain-mediated proteolysis of Myc. This generates Myc-nick, a cytoplasmic, transcriptionally inactive cleavage product of Myc. We found conversion of Myc into Myc-nick in cell lines and tissues derived from multiple cancers. In colon cancer, the production of Myc-nick is enhanced under stress conditions such as hypoxia and nutrient deprivation. Under these conditions, ectopic expression of Myc-nick promotes anchorage-independent growth and cell survival at least in part by promoting autophagy. Myc-nick also delays colon cancer cell death after treatment with chemotherapeutic drugs such as etoposide, cisplatin, and imatinib. Furthermore, colon cancer cells expressing a cleavage-resistant form of Myc undergo extensive apoptosis but are rescued by overexpression of Myc-nick. We also found that ectopic expression of Myc-nick results in the induction of the actin-bundling protein fascin, formation of filopodia, and increased cell motility—all mediators of tumor metastasis. Myc-nick-induced survival, autophagy, and motility require Myc box II (MBII), a region of Myc-nick that recruits acetyltransferases that in turn modify cytoplasmic proteins, including α-tubulin and ATG3. Our results suggest that Myc-nick-induced survival and motility contribute to colon cancer progression and metastasis. PMID:24696454

  17. Human adipose tissue-derived stem cells cultured in xeno-free culture condition enhance c-MYC expression increasing proliferation but bypassing spontaneous cell transformation.

    PubMed

    Paula, Ana C C; Martins, Thaís M M; Zonari, Alessandra; Frade, Soraia P P J; Angelo, Patrícia C; Gomes, Dawidson A; Goes, Alfredo M

    2015-04-14

    Human adipose tissue-derived stem cells (hASCs) are attractive cells for therapeutic applications and are currently being evaluated in multiple clinical trials. Prior to their clinical application, hASCs must be expanded ex vivo to obtain the required number of cells for transplantation. Fetal bovine serum is the supplement most widely used for cell culture, but it has disadvantages and it is not safe for cell therapy due to the risks of pathogen transmission and immune reaction. Furthermore, the cell expansion poses a risk of accumulating genetic abnormalities that could lead to malignant cell transformation. In this study, our aim was to evaluate the proliferation pattern as well as the resistance to spontaneous transformation of hASCs during expansion in a xeno-free culture condition. hASCs were expanded in Dulbecco's modified Eagle's medium supplemented with pooled allogeneic human serum or fetal bovine serum to enable a side-by-side comparison. Cell viability and differentiation capacity toward the mesenchymal lineages were assessed, along with immunophenotype. Ki-67 expression and the proliferation kinetics were investigated. The expression of the transcription factors c-FOS and c-MYC was examined with Western blot, and MYC, CDKN2A, ERBB2 and TERT gene expression was assessed with quantitative PCR. Senescence was evaluated by β-gal staining. Karyotype analysis was performed and tumorigenesis assay in vivo was also evaluated. The hASCs expanded in medium with pooled allogeneic human serum did not show remarkable differences in morphology, viability, differentiation capacity or immunophenotype. The main difference observed was a significantly higher proliferative effect on hASCs cultured in pooled allogeneic human serum. There was no significant difference in C-FOS expression; however, C-MYC protein expression was enhanced in pooled allogeneic human serum cultures compared to fetal bovine serum cultures. No difference was observed in MYC and TERT mRNA levels

  18. 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.

  19. Histone deacetylase class-I inhibition promotes epithelial gene expression in pancreatic cancer cells in a BRD4- and MYC-dependent manner.

    PubMed

    Mishra, Vivek Kumar; Wegwitz, Florian; Kosinsky, Robyn Laura; Sen, Madhobi; Baumgartner, Roland; Wulff, Tanja; Siveke, Jens T; Schildhaus, Hans-Ulrich; Najafova, Zeynab; Kari, Vijayalakshmi; Kohlhof, Hella; Hessmann, Elisabeth; Johnsen, Steven A

    2017-03-27

    Pancreatic ductal adenocarcinoma (PDAC) is a highly aggressive cancer with a particularly dismal prognosis. Histone deacetylases (HDAC) are epigenetic modulators whose activity is frequently deregulated in various cancers including PDAC. In particular, class-I HDACs (HDAC 1, 2, 3 and 8) have been shown to play an important role in PDAC. In this study, we investigated the effects of the class I-specific HDAC inhibitor (HDACi) 4SC-202 in multiple PDAC cell lines in promoting tumor cell differentiation. We show that 4SC-202 negatively affects TGFβ signaling and inhibits TGFβ-induced epithelial-to-mesenchymal transition (EMT). Moreover, 4SC-202 markedly induced p21 (CDKN1A) expression and significantly attenuated cell proliferation. Mechanistically, genome-wide studies revealed that 4SC-202-induced genes were enriched for Bromodomain-containing Protein-4 (BRD4) and MYC occupancy. BRD4, a well-characterized acetyllysine reader, has been shown to play a major role in regulating transcription of selected subsets of genes. Importantly, BRD4 and MYC are essential for the expression of a subgroup of genes induced by class-I HDACi. Taken together, our study uncovers a previously unknown role of BRD4 and MYC in eliciting the HDACi-mediated induction of a subset of genes and provides molecular insight into the mechanisms of HDACi action in PDAC.

  20. 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

  1. Myc inhibits JNK-mediated cell death in vivo.

    PubMed

    Huang, Jiuhong; Feng, Yu; Chen, Xinhong; Li, Wenzhe; Xue, Lei

    2017-04-01

    The proto-oncogene Myc is well known for its roles in promoting cell growth, proliferation and apoptosis. However, in this study, we found from a genetic screen that Myc inhibits, rather than promotes, cell death triggered by c-Jun N-terminal kinase (JNK) signaling in Drosophila. Firstly, expression of Drosophila Myc (dMyc) suppresses, whereas loss of dMyc enhances, ectopically activated JNK signaling-induced cell death. Secondly, dMyc impedes physiologically activated JNK pathway-mediated cell death. Thirdly, loss of dMyc triggers JNK pathway activation and JNK-dependent cell death. Finally, the mammalian cMyc gene, when expressed in Drosophila, impedes activated JNK signaling-induced cell death. Thus, besides its well-studied apoptosis promoting function, Myc also antagonizes JNK-mediated cell death in Drosophila, and this function is likely conserved from fly to human.

  2. A Myc Activity Signature Predicts Poor Clinical Outcomes in Myc-Associated Cancers.

    PubMed

    Jung, MoonSun; Russell, Amanda J; Liu, Bing; George, Joshy; Liu, Pei Yan; Liu, Tao; DeFazio, Anna; Bowtell, David D L; Oberthuer, André; London, Wendy B; Fletcher, Jamie I; Haber, Michelle; Norris, Murray D; Henderson, Michelle J

    2017-02-15

    Myc transcriptional activity is frequently deregulated in human cancers, but a Myc-driven gene signature with prognostic ability across multiple tumor types remains lacking. Here, we selected 18 Myc-regulated genes from published studies of Myc family targets in epithelial ovarian cancer (EOC) and neuroblastoma. A Myc family activity score derived from the 18 genes was correlated to MYC/MYCN/MYCL1 expression in a panel of 35 cancer cell lines. The prognostic ability of this signature was evaluated in neuroblastoma, medulloblastoma, diffuse large B-cell lymphoma (DLBCL), and EOC microarray gene expression datasets using Kaplan-Meier and multivariate Cox regression analyses and was further validated in 42 primary neuroblastomas using qPCR. Cell lines with high MYC, MYCN, and/or MYCL1 gene expression exhibited elevated expression of the signature genes. Survival analysis showed that the signature was associated with poor outcome independently of well-defined prognostic factors in neuroblastoma, breast cancer, DLBCL, and medulloblastoma. In EOC, the 18-gene Myc activity signature was capable of identifying a group of patients with poor prognosis in a "high-MYCN" molecular subtype but not in the overall cohort. The predictive ability of this signature was reproduced using qPCR analysis of an independent cohort of neuroblastomas, including a subset of tumors without MYCN amplification. These data reveal an 18-gene Myc activity signature that is highly predictive of poor prognosis in diverse Myc-associated malignancies and suggest its potential clinical application in the identification of Myc-driven tumors that might respond to Myc-targeted therapies. Cancer Res; 77(4); 971-81. ©2016 AACR. ©2016 American Association for Cancer Research.

  3. Inhibition of c-myc expression induces apoptosis of WEHI 231 murine B cells.

    PubMed Central

    Wu, M; Arsura, M; Bellas, R E; FitzGerald, M J; Lee, H; Schauer, S L; Sherr, D H; Sonenshein, G E

    1996-01-01

    Treatment of WEHI 231 immature B-lymphoma cells with an antibody against their surface immunoglobulin (anti-Ig) induces apoptosis and has been studied extensively as a model of B-cell tolerance. Anti-Ig treatment of exponentially growing WEHI 231 cells results in an early transient increase in c-myc expression that is followed by a decline to below basal levels; this decrease in c-myc expression immediately precedes the induction of cell death. Here we have modulated NF-kappaB/Rel factor activity, which regulates the rate of c-myc gene transcription, to determine whether the increase or decrease in c-Myc-levels mediates apoptosis in WEHI 231 cells. Addition of the serine/threonine protease inhibitor N-tosyl-L-phenylalanine chloromethyl ketone (TPCK), which blocks the normally rapid turnover of the specific inhibitor of NF-kappaB/Rel IkappaBalpha in these cells, caused a drop in Rel-related factor binding. TPCK treatment resulted in decreased c-myc expression, preventing the usual increase seen following anti-Ig treatment. Whereas inhibition of the induction of c-myc expression mediated by anti-Ig failed to block apoptosis, reduction of c-myc expression in exponentially growing WEHI 231 cells induced apoptosis even in the absence of anti-Ig treatment. In WEHI 231 clones ectopically expressing c-Myc, apoptosis induced by treatment with TPCK or anti-Ig was significantly diminished and cells continued to proliferate. Furthermore, apoptosis of WEHI 231 cells ensued following enhanced expression of Mad1, which has been found to reduce functional c-Myc levels. These results indicate that the decline in c-myc expression resulting from the drop in NF-kappaB/Rel binding leads to activation of apoptosis of WEHI 231 B cells. PMID:8756660

  4. LeMYC2 acts as a negative regulator of blue light mediated photomorphogenic growth, and promotes the growth of adult tomato plants

    PubMed Central

    2014-01-01

    Background Arabidopsis ZBF1/MYC2bHLH transcription factor is a repressor of photomorphogenesis, and acts as a point of cross talk in light, abscisic acid (ABA) and jasmonic acid (JA) signaling pathways. MYC2 also functions as a positive regulator of lateral root development and flowering time under long day conditions. However, the function of MYC2 in growth and development remains unknown in crop plants. Results Here, we report the functional analyses of LeMYC2 in tomato (Lycopersicon esculentum). The amino acid sequence of LeMYC2 showed extensive homology with Arabidopsis MYC2, containing the conserved bHLH domain. To study the function of LeMYC2 in tomato, overexpression and RNA interference (RNAi) LeMYC2 tomato transgenic plants were generated. Examination of seedling morphology, physiological responses and light regulated gene expression has revealed that LeMYC2 works as a negative regulator of blue light mediated photomorphogenesis. Furthermore, LeMYC2 specifically binds to the G-box of LeRBCS-3A promoter. Overexpression of LeMYC2 has led to increased root length with more number of lateral roots. The tomato plants overexpressing LeMYC2 have reduced internode distance with more branches, and display the opposite morphology to RNAi transgenic lines. Furthermore, this study shows that LeMYC2 promotes ABA and JA responsiveness. Conclusions Collectively, this study highlights that working in light, ABA and JA signaling pathways LeMYC2 works as an important regulator for growth and development in tomato plants. PMID:24483714

  5. Myc Roles in Hematopoiesis and Leukemia

    PubMed Central

    Delgado, M. Dolores; León, Javier

    2010-01-01

    Hematopoiesis is a process capable of generating millions of cells every second, as distributed in many cell types. The process is regulated by a number of transcription factors that regulate the differentiation along the distinct lineages and dictate the genetic program that defines each mature phenotype. Myc was first discovered as the oncogene of avian leukemogenic retroviruses; it was later found translocated in human lymphoma. From then on, evidence accumulated showing that c-Myc is one of the transcription factors playing a major role in hematopoiesis. The study of genetically modified mice with overexpression or deletion of Myc has shown that c-Myc is required for the correct balance between self-renewal and differentiation of hematopoietic stem cells (HSCs). Enforced Myc expression in mice leads to reduced HSC pools owing to loss of self-renewal activity at the expense of increased proliferation of progenitor cells and differentiation. c-Myc deficiency consistently results in the accumulation of HSCs. Other models with conditional Myc deletion have demonstrated that different lineages of hematopoietic cells differ in their requirement for c-Myc to regulate their proliferation and differentiation. When transgenic mice overexpress c-Myc or N-Myc in mature cells from the lymphoid or myeloid lineages, the result is lymphoma or leukemia. In agreement, enforced expression of c-Myc blocks the differentiation in several leukemia-derived cell lines capable of differentiating in culture. Not surprising, MYC deregulation is recurrently found in many types of human lymphoma and leukemia. Whereas MYC is deregulated by translocation in Burkitt lymphoma and, less frequently, other types of lymphoma, MYC is frequently overexpressed in acute lymphoblastic and myeloid leukemia, through mechanisms unrelated to chromosomal translocation, and is often associated with disease progression. PMID:21779460

  6. The Myc 3′ Wnt-Responsive Element Regulates Homeostasis and Regeneration in the Mouse Intestinal Tract

    PubMed Central

    Konsavage, Wesley M.; Jin, Ge

    2012-01-01

    The Wnt/β-catenin signaling pathway controls cellular proliferation in the intestines. In response to Wnt, β-catenin transits into the nucleus and associates with members of the T-cell factor (TCF) family of transcription factors. β-Catenin/TCF complexes bind Wnt responsive DNA elements (WREs) to activate target gene expression. The c-MYC proto-oncogene (MYC) is a direct target of β-catenin/TCF complexes. We recently identified the MYC 3′ WRE, which maps 1.4-kb downstream from the MYC transcription stop site. To investigate the role of the Myc 3′ WRE in the intestines, we generated a mouse model with a germ line deletion of this element. The intestinal architecture was largely preserved in knockout mice; however, removal of the Myc 3′ WRE compromised the crypt microenvironment. In comparison to wild-type intestines, knockout intestines contained an increased number of proliferative cells and a reduced number of differentiated cells comprising both absorptive and secretory lineages. Using a model of colitis, we found that knockout colons repaired more rapidly during the recovery period of the protocol. These results indicate that regulation of MYC expression through the Myc 3′ WRE contributes to intestinal homeostasis. Furthermore, our study implicates MYC as an important regulator of intestinal regeneration following injury. PMID:22826434

  7. The Myc Transactivation Domain Promotes Global Phosphorylation of the RNA Polymerase II Carboxy-Terminal Domain Independently of Direct DNA Binding▿ †

    PubMed Central

    Cowling, Victoria H.; Cole, Michael D.

    2007-01-01

    Myc is a transcription factor which is dependent on its DNA binding domain for transcriptional regulation of target genes. Here, we report the surprising finding that Myc mutants devoid of direct DNA binding activity and Myc target gene regulation can rescue a substantial fraction of the growth defect in myc−/− fibroblasts. Expression of the Myc transactivation domain alone induces a transcription-independent elevation of the RNA polymerase II (Pol II) C-terminal domain (CTD) kinases cyclin-dependent kinase 7 (CDK7) and CDK9 and a global increase in CTD phosphorylation. The Myc transactivation domain binds to the transcription initiation sites of these promoters and stimulates TFIIH binding in an MBII-dependent manner. Expression of the Myc transactivation domain increases CDK mRNA cap methylation, polysome loading, and the rate of translation. We find that some traditional Myc transcriptional target genes are also regulated by this Myc-driven translation mechanism. We propose that Myc transactivation domain-driven RNA Pol II CTD phosphorylation has broad effects on both transcription and mRNA metabolism. PMID:17242204

  8. Downregulation of the Genes Involved in Reprogramming (SOX2, c-MYC, miR-302, miR-145, and P21) in Gastric Adenocarcinoma.

    PubMed

    Khalili, Mitra; Vasei, Mohammad; Khalili, Davood; Alimoghaddam, Kamran; Sadeghizadeh, Majid; Mowla, Seyed Javad

    2015-09-01

    Many cell signaling pathways essential for normal stem cell development are involved in cancer initiation and progression. In the present study, motivated by a possible contribution of reprogramming process in induction of cancer, we compared the expression level of main genes involved in iPS generation, i.e., miR-302, miR-145, SOX2, c-MYC, and P21, in a series of tumor and non-tumor tissues of stomach. A total number of 34 tumors and their matched non-tumor (as control) gastric surgical specimens were obtained. The expression of the candidate genes was evaluated by using real-time PCR and immunohistochemistry (IHC) techniques. Our data revealed a significant downregulation of miR-302b, P21, and miR-145 genes in intestinal and SOX2 gene in diffuse type of tumor samples. SOX2, but not the other genes, showed a significant downregulation in both proximal (cardia and fundus) and distal (body and antrum) sites of stomach. Based on receiver-operating characteristic (ROC) analyses, the highest total area under the curve (AUC) was found for SOX2 (AUC = 82 %, P < 0.001). Interestingly, all tumor samples revealed a negative signal for c-MYC expression, while non-tumor samples represented an intense cytoplasmic staining. Despite the fact that some hESC-specific genes are upregulated in tumors, our data revealed a significant downregulation of all candidate genes, except for c-MYC, in tumor samples of stomach. Moreover, ROC data demonstrated that SOX2 gene expression index is a better potential biomarker of gastric cancer, compared to other tested genes. SOX2 expression has a good sensitivity and specificity to discriminate correctly between tumor/non-tumor and also high/low grades of tumor malignancy. It seems downregulation of miR-302b, miR-145, and P21 could contribute to gastric tumor initiation and progression.

  9. N-myc Downstream-Regulated Gene 1 (NDRG1) mediates pomegranate juice protection from apoptosis in hypoxic BeWo cells but not in primary human trophoblasts

    PubMed Central

    Chen, Baosheng; Zaveri, Parul G.; Longtine, Mark S.; Nelson, D. Michael

    2015-01-01

    Introduction N-Myc downstream-regulated gene 1 (NDRG1) expression is increased in placentas of human pregnancies with intrauterine growth restriction and in hypoxic cultured primary trophoblasts. We previously showed that elevated NDRG1 decreases trophoblast apoptosis induced by hypoxia. Separately, we found that pomegranate juice (PJ) decreases cell death induced by hypoxia in trophoblasts. Here, we test the hypothesis that PJ protects trophoblasts from hypoxia-induced apoptosis by modulating NDRG1 expression. Methods Quantitative rtPCR was used to investigate the effects of PJ treatment on mRNA levels of 22 candidate genes involved in apoptosis, oxidative stress, and differentiation in trophoblasts. Western blotting and immunofluorescence were used to analyze NDRG1 protein levels. siRNA-mediated NDRG1 knockdown was used to investigate the role of NDRG1 in response to PJ in hypoxic BeWo choriocarcinoma cells and hypoxic cultured primary human trophoblasts. Results The mRNA levels of eight genes were altered, with NDRG1 showing the largest response to PJ and thus, we pursued the role of NDRG1 here. PJ significantly increased NDRG1 protein expression in primary trophoblasts and in BeWo cells. Knockdown of NDRG1 in hypoxic BeWo cells in the presence of PJ yielded increased apoptosis. In contrast, knockdown of NDRG1 in hypoxic primary trophoblasts in the presence of PJ did not increase apoptosis. Discussion We conclude that the PJ-mediated decrease in cell death in hypoxia is partially mediated by NDRG1 in BeWo cells but not in primary trophoblasts. The disparate effects of NDRG1 between BeWo cells and primary trophoblasts indicate caution is required when extrapolating from results obtained with cell lines to primary trophoblasts. PMID:26028238

  10. The metastasis suppressor, N-myc downregulated gene 1 (NDRG1), is a prognostic biomarker for human colorectal cancer.

    PubMed

    Mao, Zhihai; Sun, Jing; Feng, Bo; Ma, Junjun; Zang, Lu; Dong, Feng; Zhang, Daohai; Zheng, Minhua

    2013-01-01

    Metastasis remains to be one of the most prevalent causes leading to poor long-term survival of colorectal cancer (CRC) patients. The clinical significances of tumor metastatic suppressor, N-myc downregulated gene 1 (NDRG1), have been inconsistently reported in a variety of cancerous diseases. In this study with 240 CRC clinical specimens, we showed that NDRG1 expression was significantly decreased in most of CRC tissues compared to the paired non-tumor counterparts. Statistical analysis revealed a significant inverse correlation of NDRG1 expression with tumor stage, differentiation status and metastasis. Compared with NDRG1-negative group, NDRG1-positve group had better disease-free/overall survival (p = 0.000) over 5 years' follow-up. Furthermore, NDRG1 was considered to be an independent prognostic factor for overall survival (p = 0.001) and recurrence (p = 0.003). Our study concludes that NDRG1 is a novel favorable predictor for the prognosis in CRC patients.

  11. The N-Myc down regulated Gene1 (NDRG1) Is a Rab4a effector involved in vesicular recycling of E-cadherin.

    PubMed

    Kachhap, Sushant K; Faith, Dennis; Qian, David Z; Shabbeer, Shabana; Galloway, Nathan L; Pili, Roberto; Denmeade, Samuel R; DeMarzo, Angelo M; Carducci, Michael A

    2007-09-05

    Cell to cell adhesion is mediated by adhesion molecules present on the cell surface. Downregulation of molecules that form the adhesion complex is a characteristic of metastatic cancer cells. Downregulation of the N-myc down regulated gene1 (NDRG1) increases prostate and breast metastasis. The exact function of NDRG1 is not known. Here by using live cell confocal microscopy and in vitro reconstitution, we report that NDRG1 is involved in recycling the adhesion molecule E-cadherin thereby stabilizing it. Evidence is provided that NDRG1 recruits on recycling endosomes in the Trans Golgi network by binding to phosphotidylinositol 4-phosphate and interacts with membrane bound Rab4aGTPase. NDRG1 specifically interacts with constitutively active Rab4aQ67L mutant protein and not with GDP-bound Rab4aS22N mutant proving NDRG1 as a novel Rab4a effector. Transferrin recycling experiments reveals NDRG1 colocalizes with transferrin during the recycling phase. NDRG1 alters the kinetics of transferrin recycling in cells. NDRG1 knockdown cells show a delay in recycling transferrin, conversely NDRG1 overexpressing cells reveal an increase in rate of transferrin recycling. This novel finding of NDRG1 as a recycling protein involved with recycling of E-cadherin will aid in understanding NDRG1 role as a metastasis suppressor protein.

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

    PubMed Central

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

    1986-01-01

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

  13. Transcriptional silencing of N-Myc downstream-regulated gene 1 (NDRG1) in metastatic colon cancer cell line SW620.

    PubMed

    Li, Qian; Chen, Hong

    2011-02-01

    N-Myc downstream-regulated gene 1 (NDRG1) plays vital roles in tumor metastasis suppression and is frequently silenced in metastatic colon cancers. NDRG1 is silenced in a highly metastatic colon cancer cell line SW620. The objective of this study was to investigate the potential mechanisms involved in silencing of the NDRG1 gene. SW480 and SW620 are two colon cancer cell lines established from the same patient with different metastatic potentials, making them an ideal model for investigation of metastatic mechanisms. Knockdown of NDRG1 in SW480 to a level that is similar to that in SW620 also modulated cell cycle and proliferation in SW480 towards the status of the highly metastatic SW620. Epigenetic mechanisms of the transcriptional control of NDRG1 were investigated. The silencing of NDRG1 in SW620 was not due to promoter hyper-methylation as bisulfite sequencing of the NDRG1 promoter showed minimal DNA methylation in both cell lines. On the other hand, chromatin immunoprecipitation showed a significantly higher level of RNA polymerase II (Pol II) association with the NDRG1 promoter in SW480 compared to SW620, in agreement with its gene expression level. The low Pol II binding at the NDRG1 promoter in SW620 was associated with gene-wide decrease in histone H4 acetylation and increase in histone H3 serine 10 phosphorylation. Meanwhile, the NDRG1 coding region showed much higher histone H3 lysine 4 methylation in SW480. In conclusion we observed unique histone modifications in two colon cancer cell lines with different metastatic potentials, indicating possible mechanisms for the down-regulation of NDRG1 in metastatic SW620.

  14. Nitric oxide suppresses tumor cell migration through N-Myc downstream-regulated gene-1 (NDRG1) expression: role of chelatable iron.

    PubMed

    Hickok, Jason R; Sahni, Sumit; Mikhed, Yuliya; Bonini, Marcelo G; Thomas, Douglas D

    2011-12-02

    N-Myc downstream-regulated gene 1 (NDRG1) is a ubiquitous cellular protein that is up-regulated under a multitude of stress and growth-regulatory conditions. Although the exact cellular functions of this protein have not been elucidated, mutations in this gene or aberrant expression of this protein have been linked to both tumor suppressive and oncogenic phenotypes. Previous reports have demonstrated that NDRG1 is strongly up-regulated by chemical iron chelators and hypoxia, yet its regulation by the free radical nitric oxide ((•)NO) has never been demonstrated. Herein, we examine the chemical biology that confers NDRG1 responsiveness at the mRNA and protein levels to (•)NO. We demonstrate that the interaction of (•)NO with the chelatable iron pool (CIP) and the appearance of dinitrosyliron complexes (DNIC) are key determinants. Using HCC 1806 triple negative breast cancer cells, we find that NDRG1 is up-regulated by physiological (•)NO concentrations in a dose- and time-dependant manner. Tumor cell migration was suppressed by NDRG1 expression and we excluded the involvement of HIF-1α, sGC, N-Myc, and c-Myc as upstream regulatory targets of (•)NO. Augmenting the chelatable iron pool abolished (•)NO-mediated NDRG1 expression and the associated phenotypic effects. These data, in summary, reveal a link between (•)NO, chelatable iron, and regulation of NDRG1 expression and signaling in tumor cells.

  15. Expression of the woodchuck N-myc2 retroposon in brain and in liver tumors is driven by a cryptic N-myc promoter.

    PubMed Central

    Fourel, G; Transy, C; Tennant, B C; Buendia, M A

    1992-01-01

    The woodchuck intronless proto-oncogene N-myc2 was initially discovered as a frequent target site for hepadnavirus integration in hepatocellular carcinoma. N-myc2 possesses characteristics of a functional retroposon derived from the woodchuck N-myc gene. We have investigated the regulatory signals governing N-myc2 expression and found that a short promoter, including a variant TATA box and potential binding sites for several transcription factors, is localized in the N-myc2 sequences homologous to the 5' untranslated region of the second N-myc exon. The corresponding region in the intron-containing woodchuck N-myc gene also exhibited promoter activity in transient transfection assays. The high evolutionary conservation of these sequences in mammalian N-myc genes suggests that they contain a cryptic N-myc promoter which may be unmasked in the particular context provided by the N-myc2 retroposon. Although N-myc2, like the woodchuck N-myc gene, contributes to an extended CpG island and was found constitutively hypomethylated, it presents a highly restricted expression pattern in adult animals. Whereas the intron-containing N-myc gene is expressed at low levels in different tissues, N-myc2 mRNA was detected only in brain tissue, raising questions about the functional significance of the maintenance of a second N-myc gene in the woodchuck genome. Images PMID:1333041

  16. Unusual concomitant rearrangements of Cyclin D1 and MYC genes in blastoid variant of mantle cell lymphoma: Case report and review of literature.

    PubMed

    Delas, Audrey; Sophie, Dobbelstein; Brousset, Pierre; Laurent, Camille

    2013-02-15

    We report herein a case of blastoid variant mantle cell lymphoma (MCL) with both aberrant phenotype and unusual genetics. Unexpectedly, lymphoma cells were CD5(-) and CD10(+). Standard karyotype and FISH techniques showed that tumor cells carried two distinct translocations which had not been reported together in a same tumor. The first translocation juxtaposed the immunoglobulin lambda light chain locus with CCND1 locus, leading to Cyclin D1 overexpression. The second translocation revealed MYC rearrangement with a non-immunoglobulin gene partner located on the short arm of chromosome 4. The interpretation of the case on tissue sections alone could have been challenging. Indeed, the lack of CD5 and expression of CD10 associated with MYC rearrangement detected on interphasic nuclei could support the diagnosis of diffuse large B-cell lymphoma or Burkitt lymphoma. This distinction is also especially important as these lymphoma subtypes require specific treatment. Copyright © 2012 Elsevier GmbH. All rights reserved.

  17. Establishment of a human herpes virus-8-negative malignant effusion lymphoma cell line (STR-428) carrying concurrent translocations of BCL2 and c-MYC genes.

    PubMed

    Taira, Tamiko; Nagasaki, Akitoshi; Tomoyose, Takeaki; Miyagi, Jun-ichi; Kakazu, Naoki; Makino, Shigeyoshi; Shinjyo, Tetsuharu; Taira, Naoya; Masuda, Masato; Takasu, Nobuyuki

    2007-09-01

    A new cell line, STR-428 was established from ascites tumor cells of a malignant effusion lymphoma patient without human herpes virus-8 (HHV-8) infection. STR-428 cells showed an immunophenotype of mature B-cells and produced few cytokines related to lymphomatous effusion. Karyotypic and genetic analysis revealed complex translocations including t(14;18)(q32;q21) effecting IgH/BCL2 and der(8)t(3;8)(q27;q24) involving c-MYC. STR-428 represents a unique, B-cell lymphoma cell line carrying concurrent rearrangement of BCL2 and c-MYC genes with features distinct from those of HHV-8-related primary effusion lymphoma. This cell line may be a valuable tool, other than HHV-8, to investigate the pathogenesis of primary lymphomatous effusion.

  18. VDR/RXR and TCF4/β-catenin cistromes in colonic cells of colorectal tumor origin: impact on c-FOS and c-MYC gene expression.

    PubMed

    Meyer, Mark B; Goetsch, Paul D; Pike, J Wesley

    2012-01-01

    Many of the transcriptional and growth regulating activities of 1α,25-dihydroxyvitamin D(3) [1,25-(OH)(2)D(3)] in the intestine and colon are recapitulated in the human colorectal cancer cell LS180. We therefore used this line together with chromatin immunoprecipitation-seq and gene expression analyses to identify the vitamin D receptor (VDR)/retinoid X receptor (RXR) and transcription factor 7-like 2 (TCF7L2/TCF4)/β-catenin cistromes and the genes that they regulate. VDR and RXR colocalized to predominantly promoter distal, vitamin D response element-containing sites in a largely ligand-dependent manner. These regulatory sites control the expression of both known as well as novel 1,25-(OH)(2)D(3) target genes. TCF4 and β-catenin cistromes partially overlapped, contained TCF/lymphoid enhancer-binding factor consensus elements, and were only modestly influenced by 1,25-(OH)(2)D(3). However, the two heterodimer complexes colocalized at sites near a limited set of genes that included c-FOS and c-MYC; the expression of both genes was modulated by 1,25-(OH)(2)D(3). At the c-FOS gene, both VDR/RXR and TCF4/β-catenin bound to a single distal enhancer located 24 kb upstream of the transcriptional start site. At the c-MYC locus, however, binding was noted at a cluster of sites between -139 and -165 kb and at a site located -335 kb upstream. Examined as isolated enhancer fragments, these regions exhibited basal and 1,25-(OH)(2)D(3)-inducible activities that were interlinked to both VDR and β-catenin activation. These data reveal additional complexity in the regulation of target genes by 1,25-(OH)(2)D(3) and support a direct action of both VDR and the TCF4/β-catenin regulatory complex at c-FOS and c-MYC.

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

    PubMed

    Sipos, Ferenc; Firneisz, Gábor; Műzes, Györgyi

    2016-09-21

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

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

    PubMed Central

    Sipos, Ferenc; Firneisz, Gábor; Műzes, Györgyi

    2016-01-01

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

  1. 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.

  2. 8q24 (C-MYC) — EDRN Public Portal

    Cancer.gov

    Chromosome region 8q24 contains the gene for MYC, also known as C-MYC. MYC is a multifunctional, nuclear phosphoprotein that plays a role in cell cycle progression, apoptosis and cellular transformation. The 8q24 region may contain a locus that influences general cancer susceptibility.

  3. RNA Polymerase I Inhibition with CX-5461 as a Novel Therapeutic Strategy to Target MYC in Multiple Myeloma.

    PubMed

    Lee, Hans C; Wang, Hua; Baladandayuthapani, Veerabhadran; Lin, Heather; He, Jin; Jones, Richard J; Kuiatse, Isere; Gu, Dongmin; Wang, Zhiqiang; Ma, Wencai; Lim, John; O'Brien, Sean; Keats, Jonathan; Yang, Jing; Davis, Richard E; Orlowski, Robert Z

    2017-04-01

    Dysregulation of MYC is frequently implicated in both early and late myeloma progression events, yet its therapeutic targeting has remained a challenge. Among key MYC downstream targets is ribosomal biogenesis, enabling increases in protein translational capacity necessary to support the growth and self-renewal programmes of malignant cells. We therefore explored the selective targeting of ribosomal biogenesis with the small molecule RNA polymerase (pol) I inhibitor CX-5461 in myeloma. CX-5461 induced significant growth inhibition in wild-type (WT) and mutant TP53 myeloma cell lines and primary samples, in association with increases in downstream markers of apoptosis. Moreover, Pol I inhibition overcame adhesion-mediated drug resistance and resistance to conventional and novel agents. To probe the TP53-independent mechanisms of CX-5461, gene expression profiling was performed on isogenic TP53 WT and knockout cell lines and revealed reduction of MYC downstream targets. Mechanistic studies confirmed that CX-5461 rapidly suppressed both MYC protein and MYC mRNA levels. The latter was associated with an increased binding of the RNA-induced silencing complex (RISC) subunits TARBP2 and AGO2, the ribosomal protein RPL5, and MYC mRNA, resulting in increased MYC transcript degradation. Collectively, these studies provide a rationale for the clinical translation of CX-5461 as a novel therapeutic approach to target MYC in myeloma.

  4. Detection of t(8;14) c-myc/IgH gene rearrangement by long-distance polymerase chain reaction in patients with diffuse large B-cell lymphoma.

    PubMed

    Kiaei, Arezoo; Onsori, Habib; Alijani, Aylar; Andalib, Sasan; Ghorbian, Saeid; Sakhinia, Ebrahim

    2016-12-01

    Specific chromosomal translocations are found in human leukemias and lymphomas. These translocations are closely related to particular histological and immunological phenotypes. In Burkitt's lymphoma, translocation t(8;14)(q24;q32), which involves the c-myc gene (8q24) and the immunoglobulin heavy-chain (IgH) locus (14q32), accounts for 90-95% of all chromosomal translocations. This translocation can be found in 2-5% of diffuse large B-cell lymphoma (DLBCL). Long-distance polymerase chain reaction (LD-PCR) assays, which can identify oncogene/Ig gene rearrangement, can detect these fusion genes. The objective of this study was to detect t(8;14) c-myc/IgH gene rearrangement by LD-PCR in patients with DLBCL. In this study, 54 DLBCL cases were tested by LD-PCR with specific primers. LD-PCR was used for two breakpoints in both the IgH gene (joining region and γ switch region) and the myc gene (Exons 2 and 3). As much as 1.85% of the samples were positive for the γ constant region and Exon 2 of the myc gene. LD-PCR can be used for the detection of t(8;14) c-myc/IgH gene rearrangement in patients with DLBCL. Copyright © 2016. Published by Elsevier Ltd.

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

    PubMed

    Chang, Ming-Xing; Ma, Yan-Ping

    2013-12-01

    The objective of this study was to investigate the effect of the new generation of tyrosine kinase inhibitor flumatinib mesylate on C-MYC, HIF-1α and VEGF in multiple myeloma (MM) cell line U266. Different concentrations (1, 5, 10 µmol/L) of flumatinib mesylate were used to act on U266 cell line for 8, 16 and 24 h, and the expression of C-MYC, and HIF-1α genes was detected by real-time fluorescence-quantitative PCR, the expression of C-MYC, HIF-1α and VEGF was measured by Western blot. The results showed that the gene expression of C-MYC and HIF-1 genes decreased gradually with the increasing of flumatinib mesylate concentration (P < 0.05). At the same concentration of flumatinib mesylate, the expression of C-MYC and HIF-1α gene decreased gradually with prolonging of treatment time with the flumatinib mesylate (P < 0.05). When the flumatinib mesylate acted the U266 cell line for 16 h, the expression of C-MYC, HIF-1α and VEGF decreased gradually with the increasing of flumatinib mesylate concentration (P < 0.05). It is concluded that the flumatinib mesylate can reduce the expression of C-MYC, HIF-1 α and VEGF in U266 cell line in a time- and dose-dependent manners, so flumatinib mesylate may become a new drug for MM therapy.

  6. 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

  7. Pim1 promotes human prostate cancer cell tumorigenicity and c-MYC transcriptional activity

    PubMed Central

    2010-01-01

    Background The serine/threonine kinase PIM1 has been implicated as an oncogene in various human cancers including lymphomas, gastric, colorectal and prostate carcinomas. In mouse models, Pim1 is known to cooperate with c-Myc to promote tumorigenicity. However, there has been limited analysis of the tumorigenic potential of Pim1 overexpression in benign and malignant human prostate cancer cells in vivo. Methods We overexpressed Pim1 in three human prostate cell lines representing different disease stages including benign (RWPE1), androgen-dependent cancer (LNCaP) and androgen-independent cancer (DU145). We then analyzed in vitro and in vivo tumorigenicity as well as the effect of Pim1 overexpression on c-MYC transcriptional activity by reporter assays and gene expression profiling using an inducible MYC-ER system. To validate that Pim1 induces tumorigenicity and target gene expression by modulating c-MYC transcriptional activity, we inhibited c-MYC using a small molecule inhibitor (10058-F4) or RNA interference. Results Overexpression of Pim1 alone was not sufficient to convert the benign RWPE1 cell to malignancy although it enhanced their proliferation rates when grown as xenografts in vivo. However, Pim1 expression enhanced the in vitro and in vivo tumorigenic potentials of the human prostate cancer cell lines LNCaP and DU145. Reporter assays revealed increased c-MYC transcriptional activity in Pim1-expressing cells and mRNA expression profiling demonstrated that a large fraction of c-MYC target genes were also regulated by Pim1 expression. The c-MYC inhibitor 10058-F4 suppressed the tumorigenicity of Pim1-expressing prostate cancer cells. Interestingly, 10058-F4 treatment also led to a reduction of Pim1 protein but not mRNA. Knocking-down c-MYC using short hairpin RNA reversed the effects of Pim1 on Pim1/MYC target genes. Conclusion Our results suggest an in vivo role of Pim1 in promoting prostate tumorigenesis although it displayed distinct oncogenic activities

  8. Myc inhibition is effective against glioma and reveals a role for Myc in proficient mitosis.

    PubMed

    Annibali, Daniela; Whitfield, Jonathan R; Favuzzi, Emilia; Jauset, Toni; Serrano, Erika; Cuartas, Isabel; Redondo-Campos, Sara; Folch, Gerard; Gonzàlez-Juncà, Alba; Sodir, Nicole M; Massó-Vallés, Daniel; Beaulieu, Marie-Eve; Swigart, Lamorna B; Mc Gee, Margaret M; Somma, Maria Patrizia; Nasi, Sergio; Seoane, Joan; Evan, Gerard I; Soucek, Laura

    2014-08-18

    Gliomas are the most common primary tumours affecting the adult central nervous system and respond poorly to standard therapy. Myc is causally implicated in most human tumours and the majority of glioblastomas have elevated Myc levels. Using the Myc dominant negative Omomyc, we previously showed that Myc inhibition is a promising strategy for cancer therapy. Here, we preclinically validate Myc inhibition as a therapeutic strategy in mouse and human glioma, using a mouse model of spontaneous multifocal invasive astrocytoma and its derived neuroprogenitors, human glioblastoma cell lines, and patient-derived tumours both in vitro and in orthotopic xenografts. Across all these experimental models we find that Myc inhibition reduces proliferation, increases apoptosis and remarkably, elicits the formation of multinucleated cells that then arrest or die by mitotic catastrophe, revealing a new role for Myc in the proficient division of glioma cells.

  9. Myc inhibition is effective against glioma and reveals a role for Myc in proficient mitosis

    PubMed Central

    Annibali, Daniela; Whitfield, Jonathan R.; Favuzzi, Emilia; Jauset, Toni; Serrano, Erika; Cuartas, Isabel; Redondo-Campos, Sara; Folch, Gerard; Gonzàlez-Juncà, Alba; Sodir, Nicole M.; Massó-Vallés, Daniel; Beaulieu, Marie-Eve; Swigart, Lamorna B.; Mc Gee, Margaret M.; Somma, Maria Patrizia; Nasi, Sergio; Seoane, Joan; Evan, Gerard I.; Soucek, Laura

    2014-01-01

    Gliomas are the most common primary tumours affecting the adult central nervous system and respond poorly to standard therapy. Myc is causally implicated in most human tumours and the majority of glioblastomas have elevated Myc levels. Using the Myc dominant negative Omomyc, we previously showed that Myc inhibition is a promising strategy for cancer therapy. Here, we preclinically validate Myc inhibition as a therapeutic strategy in mouse and human glioma, using a mouse model of spontaneous multifocal invasive astrocytoma and its derived neuroprogenitors, human glioblastoma cell lines, and patient-derived tumours both in vitro and in orthotopic xenografts. Across all these experimental models we find that Myc inhibition reduces proliferation, increases apoptosis and remarkably, elicits the formation of multinucleated cells that then arrest or die by mitotic catastrophe, revealing a new role for Myc in the proficient division of glioma cells. PMID:25130259

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

    PubMed

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

    2014-07-01

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

  11. 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.

  12. Differential regulation of GLT-1/EAAT2 gene expression by NF-κB and N-myc in male mouse brain during postnatal development.

    PubMed

    Gupta, Rajaneesh Kumar; Prasad, S

    2014-01-01

    The synaptic glutamate level homeostasis is mainly maintained by the astrocytes membrane bound glutamate transporter type-1 (GLT-1/EAAT2). Alterations in its expression during development and aging and the underlying mechanisms are not well studied. Here, we report that NF-κB interaction was highest in both cerebral and cerebellar cortices at day 15 when compared with that at day 0 during development, and it further declined significantly in day 45, and remained unchanged in 20 and 70 weeks mice. On the other hand, N-myc interaction was highest at 0 day which significantly declined at 15-day and interestingly remained unaltered at later ages in both the cortices. This age dependent reciprocal pattern of NF-κB and N-myc interactions with their cognate GLT-1 promoter sequences was further correlated with GLT-1 protein and transcript levels. We found that higher NF-κB interaction with its cognate GLT-1 promoter sequences correlates with up-regulation whereas the higher N-myc interaction correlates with down-regulation of GLT-1 expression during postnatal developmental age up to 15 day, however, such phenomenon was not found in the higher ages from day 45 to 70 weeks. Thus our data suggests a postnatal development- and age dependent differential interaction of transcription factors NF-κB and N-myc to their respective sequences and they act as positive and negative regulator, respectively of GLT-1 gene expression in the brain during early developmental period in both cerebral and cerebellar cortices which might be different in aging of mice.

  13. Kaposi Sarcoma-associated Herpesvirus vIRF-3 Protein Binds to F-box of Skp2 Protein and Acts as a Regulator of c-Myc Protein Function and Stability*

    PubMed Central

    Baresova, Petra; Pitha, Paula M.; Lubyova, Barbora

    2012-01-01

    The Kaposi sarcoma-associated herpesvirus (KSHV) has been linked to Kaposi sarcoma, body cavity-based lymphoma, and Castleman disease. vIRF-3 is a KSHV latent gene that is critical for proliferation of KSHV-positive lymphoid cells. Furthermore, vIRF-3 contributes to KSHV-associated pathogenesis by stimulating c-Myc transcription activity. Here we show that vIRF-3 can associate with Skp2, a key component of the SCFskp2 ubiquitin ligase complex. Skp2 is a transcriptional co-factor for c-Myc that was shown to regulate the stability of c-Myc protein as well as c-Myc-dependent transcription. In this study, we show that vIRF-3 binds to the F-box of Skp2 and recruits it to c-Myc-regulated promoters to activate c-Myc-dependent transcription. Additionally, cells overexpressing vIRF-3 exhibit higher levels of c-Myc ubiquitylation, suggesting that ubiquitylation is necessary for c-Myc-mediated transcription. Moreover, vIRF-3 can stabilize the c-Myc protein by increasing its half-life. Collectively, these results indicate that vIRF-3 can effectively manipulate c-Myc stability and function and thus contribute to c-Myc-induced KSHV-associated lymphomagenesis. PMID:22453922

  14. 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

  15. 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.

  16. Myc-nick: A cytoplasmic cleavage product of Myc that promotes α-tubulin acetylation and cell differentiation

    PubMed Central

    Conacci-Sorrell, Maralice; Ngouenet, Celine; Eisenman, Robert N.

    2010-01-01

    The Myc oncoprotein family comprises transcription factors that control multiple cellular functions and are widely involved in oncogenesis. Here we report the identification of Myc-nick, a cytoplasmic form of Myc generated by calpain- dependent proteolysis at lysine 298 of full-length Myc. Myc-nick retains conserved Myc Box regions but lacks nuclear localization signals and the bHLHZ domain essential for heterodimerization with Max and DNA binding. Myc-nick induces α-tubulin acetylation and altered cell morphology by recruiting histone acetyltransferase GCN5 to microtubules. During muscle differentiation, while the levels of full-length Myc diminish, Myc-nick and acetylated α-tubulin levels are increased. Ectopic expression of Myc-nick accelerates myoblast fusion, triggers the expression of myogenic markers, and permits Myc deficient fibroblasts to transdifferentiate in response to MyoD. We propose that the cleavage of Myc by calpain abrogates the transcriptional inhibition of differentiation by full-length Myc and generates Myc-nick, a driver of cytoplasmic reorganization and differentiation. PMID:20691906

  17. Parsing Myc Paralogs in Oncogenesis.

    PubMed

    Mathsyaraja, Haritha; Eisenman, Robert N

    2016-01-11

    Myc and its paralog MycN are thought to be functionally redundant, but Myc- and MycN-driven medulloblastomas exhibit distinct phenotypes. In this issue of Cancer Cell, Vo and colleagues (2016) show that this phenotypic difference stems from the preferential ability of Myc, relative to MycN, to bind Miz1 and repress transcription.

  18. Tissue aluminum concentration does not affect the genomic stability of ERBB2, C-MYC, and CCND1 genes in breast cancer.

    PubMed

    Rodrigues-Peres, Raquel Mary; Cadore, Solange; Febraio, Stefanny; Heinrich, Juliana Karina; Serra, Katia Piton; Derchain, Sophie F M; Vassallo, José; Sarian, Luis Otavio

    2013-09-01

    It has long been hypothesized that body tissue uptake of aluminum may have biological implications in breast cancer. In vitro and in vivo studies have shown that aluminum may trigger genomic instability by interfering with DNA strands. The objective of this study was to examine the relationship between aluminum concentrations in the peripheral and central areas of breast tumors with the instability of three key genes in breast cancer, ERBB2, C-MYC, and CCND1 and aneuploidy of the chromosomes harboring these genes. Tissue samples of 118 women treated for breast cancer were obtained. Evaluation of aluminum content was carried out using graphite furnace atomic absorption spectrometry. A tissue microarray slide containing the tumor samples was used in FISH assays to assess ERBB2, C-MYC, and CCND1 expressions as well as the statuses of their respective chromosomes 17, 8, and 11. Clinicopathological data were obtained from patient's records. Aluminum levels of >2.0 mg/kg were found in 20.3 and 22.1% of the central and peripheral breast tumor areas, respectively. Amplification and/or aneuploid-positive statuses for ERBB2/CEP17, C-MYC/CEP8, and CCND1/CEP11 were detected in 24, 36.7, and 29.3% of the tumors, respectively. We found that aluminum concentration was not related to these altered gene statuses. Our findings suggest that aluminum concentration does not affect genomic stability in breast tissues. Tissue microenvironment modifications, due to the presence of aluminum compounds, seem more appealing as a possible target for future studies to determine the implications of aluminum in breast carcinogenesis.

  19. Growth Suppression by Acute Promyelocytic Leukemia-Associated Protein PLZF Is Mediated by Repression of c-myc Expression

    PubMed Central

    McConnell, Melanie J.; Chevallier, Nathalie; Berkofsky-Fessler, Windy; Giltnane, Jena M.; Malani, Rupal B.; Staudt, Louis M.; Licht, Jonathan D.

    2003-01-01

    The transcriptional repressor PLZF was identified by its translocation with retinoic acid receptor alpha in t(11;17) acute promyelocytic leukemia (APL). Ectopic expression of PLZF leads to cell cycle arrest and growth suppression, while disruption of normal PLZF function is implicated in the development of APL. To clarify the function of PLZF in cell growth and survival, we used an inducible PLZF cell line in a microarray analysis to identify the target genes repressed by PLZF. One prominent gene identified was c-myc. The array analysis demonstrated that repression of c-myc by PLZF led to a reduction in c-myc-activated transcripts and an increase in c-myc-repressed transcripts. Regulation of c-myc by PLZF was shown to be both direct and reversible. An interaction between PLZF and the c-myc promoter could be detected both in vitro and in vivo. PLZF repressed the wild-type c-myc promoter in a reporter assay, dependent on the integrity of the binding site identified in vitro. PLZF binding in vivo was coincident with a decrease in RNA polymerase occupation of the c-myc promoter, indicating that repression occurred via a reduction in the initiation of transcription. Finally, expression of c-myc reversed the cell cycle arrest induced by PLZF. These data suggest that PLZF expression maintains a cell in a quiescent state by repressing c-myc expression and preventing cell cycle progression. Loss of this repression through the translocation that occurs in t(11;17) would have serious consequences for cell growth control. PMID:14645547

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

    PubMed

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

    2013-01-01

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

  1. 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

  2. Small molecule selectively suppresses MYC transcription in cancer cells.

    PubMed

    Bouvard, Claire; Lim, Sang Min; Ludka, John; Yazdani, Nahid; Woods, Ashley K; Chatterjee, Arnab K; Schultz, Peter G; Zhu, Shoutian

    2017-03-28

    Stauprimide is a staurosporine analog that promotes embryonic stem cell (ESC) differentiation by inhibiting nuclear localization of the MYC transcription factor NME2, which in turn results in down-regulation of MYC transcription. Given the critical role the oncogene MYC plays in tumor initiation and maintenance, we explored the potential of stauprimide as an anticancer agent. Here we report that stauprimide suppresses MYC transcription in cancer cell lines derived from distinct tissues. Using renal cancer cells, we confirmed that stauprimide inhibits NME2 nuclear localization. Gene expression analysis also confirmed the selective down-regulation of MYC target genes by stauprimide. Consistent with this activity, administration of stauprimide inhibited tumor growth in rodent xenograft models. Our study provides a unique strategy for selectively targeting MYC transcription by pharmacological means as a potential treatment for MYC-dependent tumors.

  3. The human zinc-finger protein-7 gene is located 90 kb 3' of MYC and is not expressed in Burkitt lymphoma cell lines.

    PubMed

    Feduchi, E; Gallego, M I; Lazo, P A

    1994-09-15

    The zinc-finger gene-7 (ZNF7) was located 90 kb 3' of MYC on human chromosome 8 band q24 by pulsed-field gel electrophoresis (PFGE). This position lies between the MLV14 and BVR1 loci, 2 variant translocation breakpoints in Burkitt lymphomas. The structure of the ZNF7 gene was not altered by translocations in Burkitt-lymphoma cell lines as shown by its germline-restriction map configuration. The chromosomal region surrounding the ZNF7 gene was extensively methylated. The ZNF7 gene was not expressed in 19 BL cell lines. Expression was detected only in the BL41 and BL47 cell lines and in the SW756 cervical-carcinoma cell line. The RNA in each was of a different size. We postulate that the lack of ZNF7 expression in Burkitt lymphomas might contribute to the tumor phenotype.

  4. Inhibitory effect of pironetin analogue/colchicine hybrids on the expression of the VEGF, hTERT and c-Myc genes.

    PubMed

    Vilanova, Concepción; Díaz-Oltra, Santiago; Murga, Juan; Falomir, Eva; Carda, Miguel; Marco, J Alberto

    2015-08-15

    A small group of hybrid molecules composed of a colchicine moiety and a pironetin analogue fragment have been investigated for their ability to inhibit the expression of the VEGF, hTERT and c-Myc genes. The VEGF gene is involved in the generation of the vascular endothelial growth factor (VEGF) and thus in the angiogenic process whereas the two latter ones are related to the activation of telomerase. All three genes therefore may be of paramount importance in the cancer generation process. It has been found that colchicine and some of its derivatives display a measurable ability to inhibit the expression of the VEGF and the two other telomerase-related genes. In the case of some of the hybrids, the available data point to the colchicine fragment being responsible for the observed biological activities. It is the first time that the last biological feature has been reported for colchicine or derivatives thereof. Copyright © 2015 Elsevier Ltd. All rights reserved.

  5. Degrasyn activates proteasomal-dependent degradation of c-Myc.

    PubMed

    Bartholomeusz, Geoffrey; Talpaz, Moshe; Bornmann, William; Kong, Ling-Yuan; Donato, Nicholas J

    2007-04-15

    c-Myc is a highly unstable transcription factor whose deregulation and increased expression are associated with cancer. Degrasyn, a small synthetic molecule, induces rapid degradation of c-Myc protein in MM-1 multiple myeloma and other tumor cell lines. Destruction of c-Myc by degrasyn requires the presence of a region of c-Myc between amino acid residues 316 and 378 that has not previously been associated with c-Myc stability. Degrasyn-induced degradation of c-Myc depends on proteasomes but is independent of the degron regions previously shown to be important for ubiquitin-mediated targeting and proteasomal destruction of the protein. Degrasyn-dependent c-Myc proteolysis is not mediated by any previously identified c-Myc regulatory mechanism, does not require new protein synthesis, and does not depend on the nuclear localization of c-Myc. Degrasyn reduced c-Myc levels in A375 melanoma cells and in A375 tumors in nude mice, and this activity correlated with tumor growth inhibition. Together, these results suggest that degrasyn reduces the stability of c-Myc in vitro and in vivo through a unique signaling process that uses c-Myc domains not previously associated with c-Myc regulation.

  6. Growing old with Myc.

    PubMed

    Carroll, Patrick A; Eisenman, Robert N

    2015-01-29

    The Myc proto-oncogene has been intensively studied in tumorigenesis and development. A new paper in Cell reports the role of Myc as a determinant of mammalian longevity. Myc heterozygous mice exhibit extended lifespans resulting from alterations in multiple cellular processes distinct from those observed in other longevity models.

  7. Calcium-dependent binding of Myc to calmodulin

    PubMed Central

    Raffeiner, Philipp; Schraffl, Andrea; Schwarz, Thomas; Röck, Ruth; Ledolter, Karin; Hartl, Markus; Konrat, Robert; Stefan, Eduard; Bister, Klaus

    2017-01-01

    The bHLH-LZ (basic region/helix-loop-helix/leucine zipper) oncoprotein Myc and the bHLH-LZ protein Max form a binary transcription factor complex controlling fundamental cellular processes. Deregulated Myc expression leads to neoplastic transformation and is a hallmark of most human cancers. The dynamics of Myc transcription factor activity are post-translationally coordinated by defined protein-protein interactions. Here, we present evidence for a second messenger controlled physical interaction between the Ca2+ sensor calmodulin (CaM) and all Myc variants (v-Myc, c-Myc, N-Myc, and L-Myc). The predominantly cytoplasmic Myc:CaM interaction is Ca2+-dependent, and the binding site maps to the conserved bHLH domain of Myc. Ca2+-loaded CaM binds the monomeric and intrinsically disordered Myc protein with high affinity, whereas Myc:Max heterodimers show less, and Max homodimers no affinity for CaM. NMR spectroscopic analyses using alternating mixtures of 15N-labeled and unlabeled preparations of CaM and a monomeric Myc fragment containing the bHLH-LZ domain corroborate the biochemical results on the Myc:CaM interaction and confirm the interaction site mapping. In electrophoretic mobility shift assays, addition of CaM does not affect high-affinity DNA-binding of Myc:Max heterodimers. However, cell-based reporter analyses and cell transformation assays suggest that increasing CaM levels enhance Myc transcriptional and oncogenic activities. Our results point to a possible involvement of Ca2+ sensing CaM in the fine-tuning of Myc function. PMID:27926480

  8. Deuterium depleted water effects on survival of lung cancer patients and expression of Kras, Bcl2, and Myc genes in mouse lung.

    PubMed

    Gyöngyi, Zoltán; Budán, Ferenc; Szabó, István; Ember, István; Kiss, István; Krempels, Krisztina; Somlyai, Ildikó; Somlyai, Gábor

    2013-01-01

    Although advances in cancer therapies continue to develop, the shortness of the survival of lung cancer patients is still disappointing. Therefore, finding new adjuvant strategies is within the focus of cancer cure. Based on observations that deuterium depletion inhibits the growth of cancer cell lines and suppresses certain proto-oncogenes, we have conducted a clinical study in 129 patients with small cell and nonsmall cell lung cancers who consumed deuterium-depleted drinking water (DDW) as a nontoxic agent in addition to conventional chemotherapy and radiotherapy. Median survival time (MST) was 25.9 mo in males and 74.1 mo in female patients; the difference between genders was statistically significant (p < 0.05). Median survival of subjects with brain metastasis was 27.1 mo. Cumulative 5-yr survival probabilities were 19%, 52%, and 33% in males, females, and all patients with brain metastasis, respectively. Gene expression analysis in mouse lung indicated that DDW attenuates 7,12-dimethylbenz(a)anthracene (DMBA)-induced expression of Bcl2, Kras, and Myc in females. In conclusion, DDW counteracts the DMBA-induced overexpression of Bcl2, Kras and Myc genes in mouse lung, and it may extend survival of lung cancer patients as a nontoxic anticancer dietary supplement, especially for women with tumors overexpressing cancer-related genes, because MST of DDW-consuming group was 2-4 times longer than it is generally observed in lung cancer patients.

  9. Deuterium Depleted Water Effects on Survival of Lung Cancer Patients and Expression of Kras, Bcl2, and Myc Genes in Mouse Lung

    PubMed Central

    Gyöngyi, Zoltán; Budán, Ferenc; Szabó, István; Ember, István; Kiss, István; Krempels, Krisztina; Somlyai, Ildikó; Somlyai, Gábor

    2013-01-01

    Although advances in cancer therapies continue to develop, the shortness of the survival of lung cancer patients is still disappointing. Therefore, finding new adjuvant strategies is within the focus of cancer cure. Based on observations that deuterium depletion inhibits the growth of cancer cell lines and suppresses certain proto-oncogenes, we have conducted a clinical study in 129 patients with small cell and nonsmall cell lung cancers who consumed deuterium-depleted drinking water (DDW) as a nontoxic agent in addition to conventional chemotherapy and radiotherapy. Median survival time (MST) was 25.9 mo in males and 74.1 mo in female patients; the difference between genders was statistically significant (p < 0.05). Median survival of subjects with brain metastasis was 27.1 mo. Cumulative 5-yr survival probabilities were 19%, 52%, and 33% in males, females, and all patients with brain metastasis, respectively. Gene expression analysis in mouse lung indicated that DDW attenuates 7,12-dimethylbenz(a)anthracene (DMBA)-induced expression of Bcl2, Kras, and Myc in females. In conclusion, DDW counteracts the DMBA-induced overexpression of Bcl2, Kras and Myc genes in mouse lung, and it may extend survival of lung cancer patients as a nontoxic anticancer dietary supplement, especially for women with tumors overexpressing cancer-related genes, because MST of DDW-consuming group was 2–4 times longer than it is generally observed in lung cancer patients. PMID:23441611

  10. Chromatin dynamics at the hTERT promoter during transcriptional activation and repression by c-Myc and Mnt in Xenopus leavis oocytes.

    PubMed

    Wahlström, Therese; Belikov, Sergey; Arsenian Henriksson, Marie

    2013-12-10

    The transcription factors c-Myc and Mnt regulate gene expression through dimerization with Max and binding to E-boxes in target genes. While c-Myc activates gene expression via recruitment of histone modifying complexes, Mnt acts as a transcriptional repressor. Here, we used the Xenopus leavis oocyte system to address the effect of c-Myc and Mnt on transcription and chromatin remodeling over the E-box region in the human telomerase reverse transcriptase (hTERT) promoter. As expected we found elevated and decreased levels of hTERT transcription upon exogenously expressed c-Myc/Max and Mnt/Max, respectively. In addition, we confirmed binding of these heterodimers to both E-boxes already enriched with H3K9ac and H4K16ac. These chromatin marks were further enhanced upon c-Myc/Max binding followed by increased DNA accessibility in the E-box region. In contrast, Mnt/Max inhibited Myc-induced transcription and mediated repression through complete chromatin condensation and deacetylation of H3K9 and H4K16 across the E-box region. Importantly, Mnt was able to counteract c-Myc mediated activation even when expressed at low levels, suggesting Mnt to act as a strong repressor by closing the chromatin structure. Collectively our data demonstrate that the balance between c-Myc and Mnt activity determines the transcriptional outcome of the hTERT promoter by modulation of the chromatin architecture.

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

    PubMed

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

    2017-09-08

    The present study was planned to study the expression of C-myc and β- catenin in triple negative breast cancer (TNBC) tissue. Furthermore, their relations to clinical features of the tumor and the survival prognosis were also studied. Additionally, correlation was evaluated between the expression of C-myc and β- catenin to provide the theoretical basis for the targeted therapy of TNBC. 60 cases of patients diagnosed with TNBC for the first time were selected for the study. The immumo-histochemical staining was employed to detect the positive expression rates of C-myc and β-catenin in cancer tissues and normal mammary tissues 3 cm away from the carcinoma. Fluorescence in situ hybridization (FISH) was used to test the gene amplification of C-myc in order to analyze the relation between C-myc and the protein expression of β-catenin. Further, kept the median follow-up time to 25.0 months in order to compare the survival prognosis. The positive expression rates of C-myc and β-catenin in cancer tissues were significantly higher than those in precancerous normal tissues (P<0.05). Further, the expression rates were related with the diameter of tumor, clinical staging, pathological grading and lymphatic metastasis (P<0.5). There were 33 cases that exhibited an increase in C-myc gene copy number and the gene amplification was observed to be 55% in total. On the other hand, patients with positive expression of C-myc and β- catenin protein exhibited a shortened disease-free survival without tumor with an increasing recurrence rate and lower survival rate (P<0.05). The present study concludes that the positive expression of C-myc and β-catenin in TNBC tissue might be closely correlated with clinical features of cancer and the survival prognosis.

  12. B-cell receptor-driven MALT1 activity regulates MYC signaling in mantle cell lymphoma.

    PubMed

    Dai, Beiying; Grau, Michael; Juilland, Mélanie; Klener, Pavel; Höring, Elisabeth; Molinsky, Jan; Schimmack, Gisela; Aukema, Sietse M; Hoster, Eva; Vogt, Niklas; Staiger, Annette M; Erdmann, Tabea; Xu, Wendan; Erdmann, Kristian; Dzyuba, Nicole; Madle, Hannelore; Berdel, Wolfgang E; Trneny, Marek; Dreyling, Martin; Jöhrens, Korinna; Lenz, Peter; Rosenwald, Andreas; Siebert, Reiner; Tzankov, Alexandar; Klapper, Wolfram; Anagnostopoulos, Ioannis; Krappmann, Daniel; Ott, German; Thome, Margot; Lenz, Georg

    2017-01-19

    Mantle cell lymphoma (MCL) is a mature B-cell lymphoma characterized by poor clinical outcome. Recent studies revealed the importance of B-cell receptor (BCR) signaling in maintaining MCL survival. However, it remains unclear which role MALT1, an essential component of the CARD11-BCL10-MALT1 complex that links BCR signaling to the NF-κB pathway, plays in the biology of MCL. Here we show that a subset of MCLs is addicted to MALT1, as its inhibition by either RNA or pharmacologic interference induced cytotoxicity both in vitro and in vivo. Gene expression profiling following MALT1 inhibition demonstrated that MALT1 controls an MYC-driven gene expression network predominantly through increasing MYC protein stability. Thus, our analyses identify a previously unappreciated regulatory mechanism of MYC expression. Investigating primary mouse splenocytes, we could demonstrate that MALT1-induced MYC regulation is not restricted to MCL, but represents a common mechanism. MYC itself is pivotal for MCL survival because its downregulation and pharmacologic inhibition induced cytotoxicity in all MCL models. Collectively, these results provide a strong mechanistic rationale to investigate the therapeutic efficacy of targeting the MALT1-MYC axis in MCL patients.

  13. c-MYC inhibition impairs hypoxia response in glioblastoma multiforme

    PubMed Central

    Falchetti, Maria Laura; Illi, Barbara; Bozzo, Francesca; Valle, Cristiana; Helmer-Citterich, Manuela; Ferrè, Fabrizio; Nasi, Sergio; Levi, Andrea

    2016-01-01

    The c-MYC oncoprotein is a DNA binding transcription factor that enhances the expression of many active genes. c-MYC transcriptional signatures vary according to the transcriptional program defined in each cell type during differentiation. Little is known on the involvement of c-MYC in regulation of gene expression programs that are induced by extracellular cues such as a changing microenvironment. Here we demonstrate that inhibition of c-MYC in glioblastoma multiforme cells blunts hypoxia-dependent glycolytic reprogramming and mitochondria fragmentation in hypoxia. This happens because c-MYC inhibition alters the cell transcriptional response to hypoxia and finely tunes the expression of a subset of Hypoxia Inducible Factor 1-regulated genes. We also show that genes whose expression in hypoxia is affected by c-MYC inhibition are able to distinguish the Proneural subtype of glioblastoma multiforme, thus potentially providing a molecular signature for this class of tumors that are the least tractable among glioblastomas. PMID:27119353

  14. Contrasting roles for c-Myc and L-Myc in the regulation of cellular growth and differentiation in vivo.

    PubMed Central

    Morgenbesser, S D; Schreiber-Agus, N; Bidder, M; Mahon, K A; Overbeek, P A; Horner, J; DePinho, R A

    1995-01-01

    Although myc family genes are differentially expressed during development, their expression frequently overlaps, suggesting that they may serve both distinct and common biological functions. In addition, alterations in their expression occur at major developmental transitions in many cell lineages. For example, during mouse lens maturation, the growth arrest and differentiation of epithelial cells into lens fiber cells is associated with a decrease in L- and c-myc expression and a reciprocal rise in N-myc levels. To determine whether the down-regulation of L- and c-myc are required for mitotic arrest and/or completion of differentiation and whether these genes have distinct or similar activities in the same cell type, we have studied the consequences of forced L- and c-myc expression in the lens fiber cell compartment using the alpha A-crystallin promoter in transgenic mice (alpha A/L-myc and alpha A/c-myc mice). With respect to morphological and molecular differentiation, alpha A/L-myc lenses were characterized by a severely disorganized lens fiber cell compartment and a significant decrease in the expression of a late-stage differentiation marker (MIP26); in contrast, differentiation appeared to be unaffected in alpha A/c-myc mice. Furthermore, an analysis of proliferation indicated that while alpha A/L-myc fiber cells withdrew properly from the cell cycle, inappropriate cell cycle progression occurred in the lens fiber cell compartment of alpha A/c-myc mice. These observations indicate that continued late-stage expression of L-myc affected differentiation processes directly, rather than indirectly through deregulated growth control, whereas constitutive c-myc expression inhibited proliferative arrest, but did not appear to disturb differentiation. As a direct corollary, our data indicate that L-Myc and c-Myc are involved in distinct physiological processes in the same cell type. Images PMID:7882978

  15. N-myc downstream-regulated gene 1 promotes tumor inflammatory angiogenesis through JNK activation and autocrine loop of interleukin-1α by human gastric cancer cells.

    PubMed

    Murakami, Yuichi; Watari, Kosuke; Shibata, Tomohiro; Uba, Manami; Ureshino, Hiroki; Kawahara, Akihiko; Abe, Hideyuki; Izumi, Hiroto; Mukaida, Naofumi; Kuwano, Michihiko; Ono, Mayumi

    2013-08-30

    The expression of N-myc downstream-regulated gene 1 (NDRG1) was significantly correlated with tumor angiogenesis and malignant progression together with poor prognosis in gastric cancer. However, the underlying mechanism for the role of NDRG1 in the malignant progression of gastric cancer remains unknown. Here we examined whether and how NDRG1 could modulate tumor angiogenesis by human gastric cancer cells. We established NU/Cap12 and NU/Cap32 cells overexpressing NDRG1 in NUGC-3 cells, which show lower tumor angiogenesis in vivo. Compared with parental NU/Mock3, NU/Cap12, and NU/Cap32 cells: 1) induced higher tumor angiogenesis than NU/Mock3 cells accompanied by infiltration of tumor-associated macrophages in mouse dorsal air sac assay and Matrigel plug assay; 2) showed much higher expression of CXC chemokines, MMP-1, and the potent angiogenic factor VEGF-A; 3) increased the expression of the representative inflammatory cytokine, IL-1α; 4) augmented JNK phosphorylation and nuclear expression of activator protein 1 (AP-1). Further analysis demonstrated that knockdown of AP-1 (Jun and/or Fos) resulted in down-regulation of the expression of VEGF-A, CXC chemokines, and MMP-1, and also suppressed expression of IL-1α in NDRG1-overexpressing cell lines. Treatment with IL-1 receptor antagonist (IL-1ra) resulted in down-regulation of JNK and c-Jun phosphorylation, and the expression of VEGF-A, CXC chemokines, and MMP-1 in NU/Cap12 and NU/Cap32 cells. Finally, administration of IL-1ra suppressed both tumor angiogenesis and infiltration of macrophages by NU/Cap12 in vivo. Together, activation of JNK/AP-1 thus seems to promote tumor angiogenesis in relationship to NDRG1-induced inflammatory stimuli by gastric cancer cells.

  16. Polyamine-modulated c-Myc expression in normal intestinal epithelial cells regulates p21Cip1 transcription through a proximal promoter region

    PubMed Central

    Liu, Lan; Guo, Xin; Rao, Jaladanki N.; Zou, Tongtong; Marasa, Bernard S.; Chen, Jie; Greenspon, Jose; Casero, Robert A.; Wang, Jian-Ying

    2006-01-01

    Maintenance of intestinal mucosal epithelial integrity requires cellular polyamines that regulate expression of various genes involved in cell proliferation, growth arrest and apoptosis. Our previous studies have shown that polyamines are essential for expression of the c-myc gene and that polyamine-induced c-Myc plays a critical role in stimulation of normal IEC (intestinal epithelial cell) proliferation, but the exact downstream targets of induced c-Myc are still unclear. The p21Cip1 protein is a major player in cell cycle control, which is primarily regulated at the transcriptional level. The current study was designed to determine whether induced c-Myc stimulates normal IEC proliferation by repressing p21Cip1 transcription following up-regulation of polyamines. Overexpression of the ODC (ornithine decarboxylase) gene increased levels of cellular polyamines, induced c-Myc expression and inhibited p21Cip1 transcription, as indicated by repression of p21Cip1 promoter activity and a decrease in p21Cip1 protein levels. In contrast, depletion of cellular polyamines by inhibiting ODC enzyme activity with α-difluoromethylornithine decreased c-Myc, but increased p21Cip1 transcription. Ectopic expression of wild-type c-myc not only inhibited basal levels of p21Cip1 transcription in control cells, but also prevented increased p21Cip1 in polyamine-deficient cells. Experiments using different p21Cip1 promoter mutants showed that transcriptional repression of p21Cip1 by c-Myc was mediated through Miz-1- and Sp1-binding sites within the proximal region of the p21Cip1 promoter in normal IECs. These findings confirm that p21Cip1 is one of the direct mediators of induced c-Myc following increased polyamines and that p21Cip1 repression by c-Myc is implicated in stimulation of normal IEC proliferation. PMID:16706751

  17. 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. Copyright © 2015 Elsevier Masson SAS. All rights reserved.

  18. 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.

  19. MYC Amplification as a Predictive Factor of Complete Pathologic Response to Docetaxel-based Neoadjuvant Chemotherapy for Breast Cancer.

    PubMed

    Pereira, Cynthia Brito Lins; Leal, Mariana Ferreira; Abdelhay, Eliana Saul Furquim Werneck; Demachki, Sâmia; Assumpção, Paulo Pimentel; de Souza, Mirian Carvalho; Moreira-Nunes, Caroline Aquino; Tanaka, Adriana Michiko da Silva; Smith, Marília Cardoso; Burbano, Rommel Rodríguez

    2017-06-01

    Neoadjuvant chemotherapy is a standard treatment for stage II and III breast cancer. The identification of biomarkers that may help in the prediction of response to neoadjuvant therapies is necessary for a more precise definition of the best drug or drug combination to induce a better response. We assessed the role of Ki67, hormone receptors expression, HER2, MYC genes and their protein status, and KRAS codon 12 mutations as predictor factors of pathologic response to anthracycline-cyclophosphamide (AC) followed by taxane docetaxel (T) neoadjuvant chemotherapy (AC+T regimen) in 51 patients with invasive ductal breast cancer. After neoadjuvant chemotherapy, 82.4% of patients showed pathologic partial response, with only 9.8% showing pathologic complete response. In multivariate analysis, MYC immunoreactivity and high MYC gain defined as MYC/nucleus ≥ 5 were significant predictor factors for pathologic partial response. Using the receiver operating characteristic curve analysis, the ratio of 2.5 MYC/CEP8 (sensitivity of 80% and specificity of 89.1%) or 7 MYC/nuclei copies (sensitivity of 80% and specificity of 73.9%) as the best cutoff in predicting a pathologic complete response was identified. Thus, MYC may have a role in chemosensitivity to AC and/or docetaxel drugs. Additionally, MYC amplification may be a predictor factor of pathologic response to the AC+T regimen in patients with breast cancer. Moreover, patients with an increased number of MYC copies showed pathologic complete response to this neoadjuvant treatment more frequently. The analysis of MYC amplification may help in the identification of patients that may have a better response to AC+T treatment. Copyright © 2016 Elsevier Inc. All rights reserved.

  20. Characterization of bipotential epidermal progenitors derived from human sebaceous gland: contrasting roles of c-Myc and beta-catenin.

    PubMed

    Lo Celso, Cristina; Berta, Melanie A; Braun, Kristin M; Frye, Michaela; Lyle, Stephen; Zouboulis, Christos C; Watt, Fiona M

    2008-05-01

    The current belief is that the epidermal sebaceous gland (SG) is maintained by unipotent stem cells that are replenished by multipotent stem cells in the hair follicle (HF) bulge. However, sebocytes can be induced by c-Myc (Myc) activation in interfollicular epidermis (IFE), suggesting the existence of bipotential stem cells. We found that every SZ95 immortalized human sebocyte that underwent clonal growth in culture generated progeny that differentiated into both sebocytes and cells expressing involucrin and cornifin, markers of IFE and HF inner root sheath differentiation. The ability to generate involucrin positive cells was also observed in a new human sebocyte line, Seb-E6E7. SZ95 xenografts differentiated into SG and IFE but not HF. SZ95 cells that expressed involucrin had reduced Myc levels; however, this did not correlate with increased expression of the Myc repressor Blimp1, and Blimp1 expression did not distinguish cells undergoing SG, IFE, or HF differentiation in vivo. Overexpression of Myc stimulated sebocyte differentiation, whereas overexpression of beta-catenin stimulated involucrin and cornifin expression. In transgenic mice simultaneous activation of Myc and beta-catenin revealed mutual antagonism: Myc blocked ectopic HF formation and beta-catenin reduced SG differentiation. Overexpression of the Myc target gene Indian hedgehog did not promote sebocyte differentiation in culture and cyclopamine treatment, while reducing proliferation, did not block Myc induced sebocyte differentiation in vivo. Our studies provide evidence for a bipotential epidermal stem cell population in an in vitro model of human epidermal lineage selection and highlight the importance of Myc as a regulator of sebocyte differentiation.

  1. Wnt/Myc interactions in intestinal cancer: partners in crime.

    PubMed

    Myant, Kevin; Sansom, Owen J

    2011-11-15

    Loss of the APC (adenomatous polyposis coli) gene in colorectal cancer leads to a rapid deregulation of TCF/LEF target genes. Of all these target genes, the transcription factor c-MYC appears the most critical. In this review we will discuss the interplay of Wnt and c-MYC signaling during intestinal homeostasis and transformation. Furthermore, we will discuss recent data showing that further deregulation of c-MYC levels during colorectal carcinogenesis may drive tumor progression. Moreover, understanding these additional control mechanisms may allow targeting of c-MYC during colorectal carcinogenesis.

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

    PubMed

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

    2016-11-16

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

  3. 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.

  4. Stat3 accelerates Myc induced tumor formation while reducing growth rate in a mouse model of breast cancer

    PubMed Central

    Jhan, Jing-Ru; Andrechek, Eran R.

    2016-01-01

    Elevated Myc expression has been noted in basal breast cancer but therapies targeting Myc directly are lacking. It is therefore critical to characterize the interaction of Myc with other genes and pathways to uncover future potential therapeutic strategies. In this study, we bioinformatically predicted a role for Stat3 in Myc induced mammary tumors and tested it using mouse models. During normal mammary function, loss of Stat3 in Myc transgenic dams resulted in lethality of pups due to lactation deficiencies. We also observed that deletion of Stat3 in the mammary glands of MMTV-Myc mice unexpectedly resulted in increased and earlier hyperplasia and expedited tumorigenesis. However, despite arising earlier, Myc tumors lacking Stat3 grew more slowly with alterations in the resulting histological subtypes, including a dramatic increase in EMT-like tumors. We also observed that these tumors had impaired angiogenesis and a slight decrease in lung metastases. This metastatic finding is distinct from previously published findings in both MMTV-Neu and MMTV-PyMT mouse models. Together, the literature and our current research demonstrate that Stat3 can function as an oncogene or as a tumor repressor depending on the oncogenic driver and developmental context. PMID:27589562

  5. c-Myc-dependent transcriptional regulation of cell cycle and nucleosomal histones during oligodendrocyte differentiation

    PubMed Central

    Magri, Laura; Gacias, Mar; Wu, Muzhou; Swiss, Victoria A; Janssen, William G; Casaccia, Patrizia

    2014-01-01

    Oligodendrocyte progenitor cells (OPCs) have the ability to divide or to arrest growth and differentiate into myelinating oligodendrocytes in the developing brain. Due to their high number and the persistence of their proliferative capacity in the adult brain, OPCs are being studied as potential targets for myelin repair and also as potential source of brain tumors. This study addresses the molecular mechanisms regulating the transcriptional changes occurring at the critical transition between proliferation and cell cycle exit in cultured OPCs. Using bioinformatic analysis of existing datasets, we identified c-Myc as a key transcriptional regulator of this transition and confirmed direct binding of this transcription factor to identified target genes using chromatin immunoprecipitation. The expression of c-Myc was elevated in proliferating OPCs, where it also bound to the promoter of genes involved in cell cycle regulation (i.e. Cdc2) or chromosome organization (i.e. H2afz). Silencing of c-Myc was associated with decreased histone acetylation at target gene promoters and consequent decrease of gene transcripts. c-Myc silencing induced also a global increase of repressive histone methylation and premature nuclear peripheral chromatin compaction and promoted the progression of OPCs towards differentiation. We conclude that c-Myc is an important modulator of the transition between proliferation and differentiation of OPCs, although its decrease is not sufficient to induce progression into a myelinating phenotype. PMID:24502923

  6. DJ-1, an oncogene and causative gene for familial Parkinson's disease, is essential for SV40 transformation in mouse fibroblasts through up-regulation of c-Myc.

    PubMed

    Kim, Yun Chul; Kitaura, Hirotake; Iguchi-Ariga, Sanae M M; Ariga, Hiroyoshi

    2010-09-24

    Simian virus 40 (SV40) is a tumor virus and its early gene product large T-antigen (LT) is responsible for the transforming activity of SV40. Parkinson's disease causative gene DJ-1 is also a ras-dependent oncogene, but the mechanism of its oncogene function is still not known. In this study, we found that there were no transformed foci when fibroblasts from DJ-1-knockout mice were transfected with LT. We also found that DJ-1 directly bound to LT and that the expression level of c-Myc in transformed cells was parallel to that of DJ-1. These findings indicate that DJ-1 is essential for SV40 transformation.

  7. Expression and activity of L-Myc in normal mouse development.

    PubMed Central

    Hatton, K S; Mahon, K; Chin, L; Chiu, F C; Lee, H W; Peng, D; Morgenbesser, S D; Horner, J; DePinho, R A

    1996-01-01

    To determine the role of L-Myc in normal mammalian development and its functional relationship to other members of the Myc family, we determined the normal patterns of L-myc gene expression in the developing mouse by RNA in situ hybridization and assessed the phenotypic impact of L-Myc deficiency produced through standard gene targeting methodology. L-myc transcripts were detected in the developing kidney and lung as well as in both the proliferative and the differentiative zones of the brain and neural tube. Despite significant expression of L-myc in developing mouse tissue, homozygous null L-myc mice were found to be viable, reproductively competent, and represented in expected frequencies from heterozygous matings. A detailed histological survey of embryonic and adult tissues, characterization of an embryonic neuronal marker, and measurement of cellular proliferation in situ did not reveal any congenital abnormalities. The lack of an apparent phenotype associated with L-Myc deficiency indicates that L-Myc is dispensable for gross morphological development and argues against a unique role for L-Myc in early central nervous system development as had been previously suggested. Although overlapping expression patterns among myc family members raise the possibility of complementation of L-Myc deficiency by other Myc oncoproteins, compensatory changes in the levels of c- and/or N-myc transcripts were not detected in homozygous null L-myc mice. PMID:8657155

  8. 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

  9. Myc target gene, long intergenic noncoding RNA, Linc00176 in hepatocellular carcinoma regulates cell cycle and cell survival by titrating tumor suppressor microRNAs.

    PubMed

    Tran, D D H; Kessler, C; Niehus, S E; Mahnkopf, M; Koch, A; Tamura, T

    2017-09-04

    Hepatocellular carcinoma (HCC) is a frequent form of cancer with a poor prognosis and with limited possibilities for medical intervention. Recent evidence has accumulated that long noncoding RNAs (lncRNAs) are important regulators of disease processes including cancer. Chromatin remodeling in cancer cells may result in an unusual expression of lncRNAs and indeed it has been shown that more than 7000 unannotated lncRNAs are expressed in HCCs. We identified a novel long intergenic noncoding RNA, Linc00176, that plays a role in proliferation and survival of HCC. Linc00176 regulates expression of more than 200 genes by the sponge function for tumor suppressor miRNAs, miR-9 and miR-185. Linc00176 is expressed at a high level only in HCC, and is activated by Myc, Max and AP-4 transcription regulators. Myc also upregulates miR-9 and miR-185. In Linc00176-depleted HCC, these miRNAs were released from Linc00176 and downregulated their target mRNAs. Thus, depletion of Linc00176 disrupted the cell cycle and induced necroptosis in HCC via released tumor suppressor miRNAs. These data indicate that atypically expressed lncRNAs may be useful targets for cancer therapy.Oncogene advance online publication, 4 September 2017; doi:10.1038/onc.2017.312.

  10. Antioxidant α-tocopherol checks lymphoma promotion via regulation of expression of protein kinase C-α and c-Myc genes and glycolytic metabolism.

    PubMed

    Sharma, Renu; Vinayak, Manjula

    2012-06-01

    Overproduction of reactive oxygen species (ROS) due to environmental challenge or metabolic imbalance leads to oxidative stress, causing overactivation of a number of oncogenes that promote cancer development. Therefore, antioxidants should be able to check cancer growth by modulating oncogene activity. The requirement of high energy during unlimited cell proliferation is fulfilled by the switching of cancerous cells to a fast glycolytic pathway bypassing the oxygen dependent respiratory pathway. Almost all cancers exhibit a high expression of lactate dehydrogenase A (LDH-A) to ensure a high energy supply. The present study focused on modulating redox-sensitive oncogenes such as protein kinase C (PKC) and c-Myc by treatment of lymphoma bearing mice with the antioxidant α-tocopherol, the most active component of vitamin E. Further, the impact of α-tocopherol on LDH activity was tested. The results showed down-regulation of expression of stress-activated genes PKC-α, c-Myc and LDH-A by α-tocopherol in cancerous mice. α-Tocopherol contributes to the check of cell proliferation by decreasing the activity of LDH-A.

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

    PubMed

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

    2015-12-09

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

  12. 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

  13. MYC overexpression correlates with MYC amplification or translocation, and is associated with poor prognosis in mantle cell lymphoma.

    PubMed

    Choe, Ji-Young; Yun, Ji Yun; Na, Hee Young; Huh, Jooryung; Shin, Su-Jin; Kim, Hyun-Jung; Paik, Jin Ho; Kim, Young A; Nam, Soo Jeong; Jeon, Yoon Kyung; Park, Gyeongsin; Kim, Ji Eun

    2016-02-01

    We aimed to investigate MYC expression and chromosomal aberration in mantle cell lymphoma (MCL), and the clinical significance of these factors. Sixty-five patients with MCL, including 54 classic, nine blastoid and two pleomorphic variants, were enrolled. Expression of MYC, Ki67 and p53 was assessed by immunohistochemistry. MYC amplification or translocation was examined by fluorescence in-situ hybridization. MYC expression was higher in blastoid/pleomorphic MCL variants (mean, 19.0%) than in classic MCL (mean, 1.9%; P < 0.001). Expression of p53 and Ki67 was also significantly higher in these variants. MYC amplification was found in two of 53 cases tested, both of which were blastoid variants with high MYC expression (29.7% and 20.4%). MYC translocation was found in two of 52 cases tested, both of which were pleomorphic variants with remarkably high MYC expression (68.5% and 71.0%). High MYC or p53 expression was significantly associated with shortened overall survival and progression-free survival in univariable and multivariable analyses (all P < 0.05). MYC overexpression is a negative predictor of MCL patient outcomes. MYC gene amplification or translocation might be related to the pathogenesis of MCL, particularly in blastoid/pleomorphic variants. © 2015 John Wiley & Sons Ltd.

  14. 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

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

    PubMed Central

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

    2014-01-01

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

  16. 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

  17. Targeting MYC dependence in cancer by inhibiting BET bromodomains

    PubMed Central

    Mertz, Jennifer A.; Conery, Andrew R.; Bryant, Barbara M.; Sandy, Peter; Balasubramanian, Srividya; Mele, Deanna A.; Bergeron, Louise; Sims, Robert J.

    2011-01-01

    The MYC transcription factor is a master regulator of diverse cellular functions and has been long considered a compelling therapeutic target because of its role in a range of human malignancies. However, pharmacologic inhibition of MYC function has proven challenging because of both the diverse mechanisms driving its aberrant expression and the challenge of disrupting protein–DNA interactions. Here, we demonstrate the rapid and potent abrogation of MYC gene transcription by representative small molecule inhibitors of the BET family of chromatin adaptors. MYC transcriptional suppression was observed in the context of the natural, chromosomally translocated, and amplified gene locus. Inhibition of BET bromodomain–promoter interactions and subsequent reduction of MYC transcript and protein levels resulted in G1 arrest and extensive apoptosis in a variety of leukemia and lymphoma cell lines. Exogenous expression of MYC from an artificial promoter that is resistant to BET regulation significantly protected cells from cell cycle arrest and growth suppression by BET inhibitors. MYC suppression was accompanied by deregulation of the MYC transcriptome, including potent reactivation of the p21 tumor suppressor. Treatment with a BET inhibitor resulted in significant antitumor activity in xenograft models of Burkitt's lymphoma and acute myeloid leukemia. These findings demonstrate that pharmacologic inhibition of MYC is achievable through targeting BET bromodomains. Such inhibitors may have clinical utility given the widespread pathogenetic role of MYC in cancer. PMID:21949397

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

    PubMed Central

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

    2016-01-01

    Expression of the oncogenic transcription factor MYC is disproportionately elevated in triple-negative breast cancer (TNBC) compared to estrogen, progesterone and human epidermal growth factor 2 receptor-positive (RP) breast tumors1,2. We and others have shown that MYC alters metabolism during tumorigenesis3,4. However, the role of MYC in TNBC metabolism remains largely unexplored. We hypothesized that MYC-dependent metabolic dysregulation is essential for MYC-overexpressing (MO) TNBC and may thus identify novel 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. A lipid metabolism gene signature was identified in patients with TNBC from The Cancer Genome Atlas (TCGA) database and multiple other clinical datasets, implicating FAO as a dysregulated pathway critical for TNBC metabolism. We find that MO-TNBC displays increased bioenergetic reliance upon fatty acid oxidation (FAO), and that pharmacologic inhibition of FAO catastrophically decreases energy metabolism of MO-TNBC, blocks growth of a MYC-driven transgenic TNBC model and that of MO-TNBC patient-derived xenografts. Our results demonstrate that inhibition of FAO is a novel therapeutic strategy against MO-TNBC. PMID:26950360

  19. c-myc and N-myc promote active stem cell metabolism and cycling as architects of the developing brain.

    PubMed

    Wey, Alice; Knoepfler, Paul S

    2010-06-01

    myc genes are associated with a wide variety of human cancers including most types of nervous system tumors. While the mechanisms by which myc overexpression causes tumorigenesis are multifaceted and have yet to be clearly elucidated, they are at least in part related to endogenous myc function in normal cells. Knockout (KO) of either c-myc or N-myc genes in neural stem and precursor cells (NSC) driven by nestin-cre impairs mouse brain growth and mutation of N-myc also causes microcephaly in humans in Feingold Syndrome. To further define myc function in NSC and nervous system development, we created a double KO (DKO) for c- and N-myc using nestin-cre. The DKO mice display profoundly impaired overall brain growth associated with decreased cell cycling and migration of NSC, which are strikingly decreased in number. The DKO brain also exhibits specific changes in gene expression including downregulation of genes involved in protein and nucleotide metabolism, mitosis, and chromatin structure as well as upregulation of genes associated with differentiation. Together these data support a model of nervous system tumorigenesis in which excess myc aberrantly locks in a developmentally active chromatin state characterized by overactive cell cycling, and metabolism as well as blocked differentiation.

  20. A deletion in the N-myc downstream regulated gene 1 (NDRG1) gene in Greyhounds with polyneuropathy.

    PubMed

    Drögemüller, Cord; Becker, Doreen; Kessler, Barbara; Kemter, Elisabeth; Tetens, Jens; Jurina, Konrad; Jäderlund, Karin Hultin; Flagstad, Annette; Perloski, Michele; Lindblad-Toh, Kerstin; Matiasek, Kaspar

    2010-06-22

    The polyneuropathy of juvenile Greyhound show dogs shows clinical similarities to the genetically heterogeneous Charcot-Marie-Tooth (CMT) disease in humans. The pedigrees containing affected dogs suggest monogenic autosomal recessive inheritance and all affected dogs trace back to a single male. Here, we studied the neuropathology of this disease and identified a candidate causative mutation. Peripheral nerve biopsies from affected dogs were examined using semi-thin histology, nerve fibre teasing and electron microscopy. A severe chronic progressive mixed polyneuropathy was observed. Seven affected and 17 related control dogs were genotyped on the 50k canine SNP chip. This allowed us to localize the causative mutation to a 19.5 Mb interval on chromosome 13 by homozygosity mapping. The NDRG1 gene is located within this interval and NDRG1 mutations have been shown to cause hereditary motor and sensory neuropathy-Lom in humans (CMT4D). Therefore, we considered NDRG1 a positional and functional candidate gene and performed mutation analysis in affected and control Greyhounds. A 10 bp deletion in canine NDRG1 exon 15 (c.1080_1089delTCGCCTGGAC) was perfectly associated with the polyneuropathy phenotype of Greyhound show dogs. The deletion causes a frame shift (p.Arg361SerfsX60) which alters several amino acids before a stop codon is encountered. A reduced level of NDRG1 transcript could be detected by RT-PCR. Western blot analysis demonstrated an absence of NDRG1 protein in peripheral nerve biopsy of an affected Greyhound. We thus have identified a candidate causative mutation for polyneuropathy in Greyhounds and identified the first genetically characterized canine CMT model which offers an opportunity to gain further insights into the pathobiology and therapy of human NDRG1 associated CMT disease. Selection against this mutation can now be used to eliminate polyneuropathy from Greyhound show dogs.

  1. N-myc downstream regulated gene1/Cap43 overexpression suppresses tumor growth by hepatic cancer cells through cell cycle arrest at the G0/G1 phase.

    PubMed

    Akiba, Jun; Murakami, Yuichi; Noda, Masaki; Watari, Kosuke; Ogasawara, Sachiko; Yoshida, Takafumi; Kawahara, Akihiko; Sanada, Sakiko; Yasumoto, Makiko; Yamaguchi, Rin; Kage, Masayoshi; Kuwano, Michihiko; Ono, Mayumi; Yano, Hirohisa

    2011-11-01

    N-myc downstream regulated gene-1 (NDRG1)/Cap43 regulates tumor growth and metastasis in various carcinomas. In this study we examined whether and how NDRG1/Cap43 modulates tumor growth by human hepatocellular carcinoma (HCC) cells. NDRG1/Cap43 cDNA was used to transfect HCC cell lines (KIM-1), and stable transfectants overexpressing NDRG1/Cap43 (KIM-1/Cap43) were obtained. Cell cycle analysis showed that KIM-1/Cap43 cells were arrested in the G0/G1 phase. Western blot analysis demonstrated an increase in p21 in KIM-1/Cap43 cells in culture under full confluency as compared with KIM-1/Mock. When KIM-1 cells, which are very low in NDRG1/Cap43 expression, were treated with mimosine, a G0/G1 cell cycle blocker, expression of NDRG1/Cap43 was induced in a dose dependent manner, together with p21 induction and CDK4 reduction. In vivo, KIM-1/Cap43 cells showed markedly decreased tumor growth rates compared with those of KIM-1/Mock. Immunohistochemical staining demonstrated markedly higher p21 labeling index in the KIM-1/Cap43 tumor than KIM-1/Mock tumor, and lower CDK4 and Ki-67 labeling index in the KIM-1/Cap43 than KIM-1/Mock. In order to confirm suppressive effects of NDRG1/Cap43, we further established a stable transfectant expressing NDRG1/Cap43 (HAK-1B/Cap43) using another HCC cell line, HAK-1B. Western blot analysis demonstrated an increase in p21 and a decrease in CDK4 in HAK-1B/Cap43 cells in culture under full confluency as compared with HAK-1B/Mock. HAK-1B/Cap43 also showed decreased tumor growth rates as compared with its control counterpart in vivo. NDRG1/Cap43 overexpression thus induced cell cycle arrest at the G0/G1 phase accompanied by increased p21 and decreased CDK4 expression in HCC cells. NDRG1/Cap43 might play a key role in the cell cycle control of G0/G1 in HCC cells.

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

    DOE PAGES

    Ledee, Dolena; Smith, Lincoln; Bruce, Margaret; ...

    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

  3. 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.

  4. Molecular cytogenetic analyses of hTERC (3q26) and MYC (8q24) genes amplifications in correlation with oncogenic human papillomavirus infection in Czech patients with cervical intraepithelial neoplasia and cervical carcinomas.

    PubMed

    Kuglik, P; Kasikova, K; Smetana, J; Vallova, V; Lastuvkova, A; Moukova, L; Cvanova, M; Brozova, L

    2015-01-01

    It is known that cervical cancer develop from precancerous intraepithelial neoplasia (CIN) which is characterized by series of genetic abnormalities. The progression of CIN to cervical carcinoma has been associated especially with the genomic integration of oncogenic human papilloma virus (HPV) and gain of the human telomerase RNA gene hTERC (3q26) and MYC (8q24). In this study, cytology specimens of cervical intraepithelial neoplasia and cervical carcinoma from 74 Czech women were analyzed using the triple-color Cervical FISH Probe Kit designed for identification of HPV infected cells and copy number aberration of the hTERC and MYC genes. HPV-positivity exhibited 70% of patients with premalignant lesions (CIN I - CIN III, carcinoma in situ), chromosomal changes were found in 53.3% of cases - MYC amplification had 33.3% of women with CIN I - CIN III and 50% with carcinoma in situ. Amplification of hTERC was detected in 16.7% of patient with CIN I, in 50% with CIN II, in 58.3% with CIN III and in 66.7% with carcinoma in situ. Based on HPV-positivity and the occurrence of chromosomal aberrations, patients were divided into high-, intermediate- and low-risk group. Among women with cervical carcinomas, HPV infection was detected in 90.1% of specimens and chromosomal aberrations were found in 87.5% of samples. Amplification of MYC gene was detected in 25% and hTERC gene in 62.5% of patients. According to the histopathological grade of tumors, MYC gene amplification occurred more frequently in specimens of spinocellular carcinoma than adenocarcinoma (p=0.029). We found no association between the frequency of cytogenetic lesions and the incidence of lymphangiogenesis or lymph node metastases in cervical carcinoma patients. Simultaneous hTERC and MYC genes amplification was significantly more frequent in samples of cervical carcinomas than in premalignant lesions (p=0.008).In a cohort of 26 patients with cervical carcinoma we used oligo-based GGH+SNP microarray

  5. A c-Myc regulatory subnetwork from human transposable element sequences†‡

    PubMed Central

    Wang, Jianrong; Bowen, Nathan J.; Mariño-Ramírez, Leonardo

    2010-01-01

    Transposable elements (TEs) can donate regulatory sequences that help to control the expression of human genes. The oncogene c-Myc is a promiscuous transcription factor that is thought to regulate the expression of hundreds of genes. We evaluated the contribution of TEs to the c-Myc regulatory network by searching for c-Myc binding sites derived from TEs and by analyzing the expression and function of target genes with nearby TE-derived c-Myc binding sites. There are thousands of TE sequences in the human genome that are bound by c-Myc. A conservative analysis indicated that 816–4564 of these TEs contain canonical c-Myc binding site motifs. c-Myc binding sites are over-represented among sequences derived from the ancient TE families L2 and MIR, consistent with their preservation by purifying selection. Genes associated with TE-derived c-Myc binding sites are co-expressed with each other and with c-Myc. A number of these putative TE-derived c-Myc target genes are differentially expressed between Burkitt’s lymphoma cells versus normal B cells and encode proteins with cancer-related functions. Despite several lines of evidence pointing to their regulation by c-Myc and relevance to cancer, the set of genes identified as TE-derived c-Myc targets does not significantly overlap with two previously characterized c-Myc target gene sets. These data point to a substantial contribution of TEs to the regulation of human genes by c-Myc. Genes that are regulated by TE-derived c-Myc binding sites appear to form a distinct c-Myc regulatory subnetwork. PMID:19763338

  6. MYC/BCL2 protein coexpression contributes to the inferior survival of activated B-cell subtype of diffuse large B-cell lymphoma and demonstrates high-risk gene expression signatures: a report from The International DLBCL Rituximab-CHOP Consortium Program

    PubMed Central

    Hu, Shimin; Xu-Monette, Zijun Y.; Tzankov, Alexander; Green, Tina; Wu, Lin; Balasubramanyam, Aarthi; Liu, Wei-min; Visco, Carlo; Li, Yong; Miranda, Roberto N.; Montes-Moreno, Santiago; Dybkaer, Karen; Chiu, April; Orazi, Attilio; Zu, Youli; Bhagat, Govind; Richards, Kristy L.; Hsi, Eric D.; Choi, William W. L.; Zhao, Xiaoying; van Krieken, J. Han; Huang, Qin; Huh, Jooryung; Ai, Weiyun; Ponzoni, Maurilio; Ferreri, Andrés J. M.; Zhou, Fan; Slack, Graham W.; Gascoyne, Randy D.; Tu, Meifeng; Variakojis, Daina; Chen, Weina; Go, Ronald S.; Piris, Miguel A.; Møller, Michael B.; Medeiros, L. Jeffrey; Young, Ken H.

    2013-01-01

    Diffuse large B-cell lymphoma (DLBCL) is stratified into prognostically favorable germinal center B-cell (GCB)–like and unfavorable activated B-cell (ABC)–like subtypes based on gene expression signatures. In this study, we analyzed 893 de novo DLBCL patients treated with R-CHOP (rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone). We show that MYC/BCL2 protein coexpression occurred significantly more commonly in the ABC subtype. Patients with the ABC or GCB subtype of DLBCL had similar prognoses with MYC/BCL2 coexpression and without MYC/BCL2 coexpression. Consistent with the notion that the prognostic difference between the 2 subtypes is attributable to MYC/BCL2 coexpression, there is no difference in gene expression signatures between the 2 subtypes in the absence of MYC/BCL2 coexpression. DLBCL with MYC/BCL2 coexpression demonstrated a signature of marked downregulation of genes encoding extracellular matrix proteins, those involving matrix deposition/remodeling and cell adhesion, and upregulation of proliferation-associated genes. We conclude that MYC/BCL2 coexpression in DLBCL is associated with an aggressive clinical course, is more common in the ABC subtype, and contributes to the overall inferior prognosis of patients with ABC-DLBCL. In conclusion, the data suggest that MYC/BCL2 coexpression, rather than cell-of-origin classification, is a better predictor of prognosis in patients with DLBCL treated with R-CHOP. PMID:23449635

  7. MYC/BCL2 protein coexpression contributes to the inferior survival of activated B-cell subtype of diffuse large B-cell lymphoma and demonstrates high-risk gene expression signatures: a report from The International DLBCL Rituximab-CHOP Consortium Program.

    PubMed

    Hu, Shimin; Xu-Monette, Zijun Y; Tzankov, Alexander; Green, Tina; Wu, Lin; Balasubramanyam, Aarthi; Liu, Wei-min; Visco, Carlo; Li, Yong; Miranda, Roberto N; Montes-Moreno, Santiago; Dybkaer, Karen; Chiu, April; Orazi, Attilio; Zu, Youli; Bhagat, Govind; Richards, Kristy L; Hsi, Eric D; Choi, William W L; Zhao, Xiaoying; van Krieken, J Han; Huang, Qin; Huh, Jooryung; Ai, Weiyun; Ponzoni, Maurilio; Ferreri, Andrés J M; Zhou, Fan; Slack, Graham W; Gascoyne, Randy D; Tu, Meifeng; Variakojis, Daina; Chen, Weina; Go, Ronald S; Piris, Miguel A; Møller, Michael B; Medeiros, L Jeffrey; Young, Ken H

    2013-05-16

    Diffuse large B-cell lymphoma (DLBCL) is stratified into prognostically favorable germinal center B-cell (GCB)-like and unfavorable activated B-cell (ABC)-like subtypes based on gene expression signatures. In this study, we analyzed 893 de novo DLBCL patients treated with R-CHOP (rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone). We show that MYC/BCL2 protein coexpression occurred significantly more commonly in the ABC subtype. Patients with the ABC or GCB subtype of DLBCL had similar prognoses with MYC/BCL2 coexpression and without MYC/BCL2 coexpression. Consistent with the notion that the prognostic difference between the 2 subtypes is attributable to MYC/BCL2 coexpression, there is no difference in gene expression signatures between the 2 subtypes in the absence of MYC/BCL2 coexpression. DLBCL with MYC/BCL2 coexpression demonstrated a signature of marked downregulation of genes encoding extracellular matrix proteins, those involving matrix deposition/remodeling and cell adhesion, and upregulation of proliferation-associated genes. We conclude that MYC/BCL2 coexpression in DLBCL is associated with an aggressive clinical course, is more common in the ABC subtype, and contributes to the overall inferior prognosis of patients with ABC-DLBCL. In conclusion, the data suggest that MYC/BCL2 coexpression, rather than cell-of-origin classification, is a better predictor of prognosis in patients with DLBCL treated with R-CHOP.

  8. Recombinant interleukin 2 regulates levels of c-myc mRNA in a cloned murine T lymphocyte.

    PubMed Central

    Reed, J C; Sabath, D E; Hoover, R G; Prystowsky, M B

    1985-01-01

    The cellular oncogene c-myc has been implicated in the regulation of growth of normal and neoplastic cells. Recently, it was suggested that c-myc gene expression may control the G0----G1-phase transition in normal lymphocytes that were stimulated to enter the cell cycle by the lectin concanavalin A (ConA). Here we describe the effects of purified recombinant interleukin 2 (rIL2) and of ConA on levels of c-myc mRNA in the noncytolytic murine T-cell clone L2. In contrast to resting (G0) primary cultures of lymphocytes, quiescent L2 cells have a higher RNA content than resting splenocytes and express receptors for interleukin 2 (IL2). Resting L2 cells are therefore best regarded as early G1-phase cells. Purified rIL2 was found to stimulate the rapid accumulation of c-myc mRNA in L2 cells. Levels of c-myc mRNA became maximal within 1 h and declined gradually thereafter. In contrast, ConA induced slower accumulation of c-myc mRNA in L2 cells, with increased levels of c-myc mRNA becoming detectable 4 to 8 h after stimulation. Experiments with the protein synthesis inhibitor cycloheximide demonstrated that the increase in levels of c-myc mRNA that were induced by ConA was a direct effect of this lectin and not secondary to IL2 production. Cyclosporin A, an immunosuppressive agent, markedly reduced the accumulation of c-myc mRNA that was induced by ConA but only slightly diminished the accumulation of c-myc mRNA that was induced by rIL2. Taken together, these data provide evidence that (i) c-myc gene expression can be regulated by at least two distinct pathways in T lymphocytes, only one of which is sensitive to cyclosporine A, and (ii) the accumulation of c-myc mRNA can be induced in T cells by IL2 during the G1 phase of the cell cycle. Images PMID:3879814

  9. Quantitative determination of c-myc facilitates the assessment of prognosis of OSCC patients.

    PubMed

    Pérez-Sayáns, M; Suárez-Peñaranda, J M; Padín-Iruegas, E; Gayoso-Diz, P; Reis-De Almeida, M; Barros-Angueira, F; Gándara-Vila, P; Blanco-Carrión, A; García-García, A

    2014-04-01

    Myc genes are a family of proto-oncogenes whose proteins are implicated in the regulation of cell proliferation, differentiation and apoptosis, and in regulating the activity of genes involved in cell division. The aim of the present study was to establish a quantitative description of the expression of c-myc and evaluate its relationship with other clinical and prognostic factors, as well as to establish a multivariate survival prediction model. This is a retrospective study of 68 patients diagnosed with oral squamous cell carcinoma (OSCC). We constructed a tissue microarray for investigating the expression of c-myc by immunohistochemistry. Statistical analyses were carried out, and a multivariate model that predicts survival was established. The average expression of c-myc was 50.32 (SD, 26.05) with a range from 6.60 to 99.48; similar for initial and advanced tumor stages. Non-smoking patients had higher levels of c-myc, showing statistically significant differences (Kruskal-Wallis χ2=5.975; p=0.05). We found no statistically significant relationship between the quantitative expression of c-myc and any other clinical or pathological parameters. For each unit of increase of c-myc, the risk increased by 1.15 (p<0.001; HR, 1.150; 95% CI, 1062-1245). Further study of this protein, which may have a significant diagnostic, prognostic and therapeutic value is warranted. Its determination can be valuable when used together with other markers to assess the prognosis of OSCC patients.

  10. Therapeutic Strategies to Inhibit MYC

    PubMed Central

    McKeown, Michael R.; Bradner, James E.

    2014-01-01

    MYC is a master regulator of stem cell state, embryogenesis, tissue homeostasis, and aging. As in health, in disease MYC figures prominently. Decades of biological research have identified a central role for MYC in the pathophysiology of cancer, inflammation, and heart disease. The centrality of MYC to such a vast breadth of disease biology has attracted significant attention to the historic challenge of developing inhibitors of MYC. This review will discuss therapeutic strategies toward the development of inhibitors of MYC-dependent transcriptional signaling, efforts to modulate MYC stability, and the elusive goal of developing potent, direct-acting inhibitors of MYC. PMID:25274755

  11. 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

    2014-04-04

    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.

  12. Therapeutic Approaches Targeting MYC-Driven Prostate Cancer

    PubMed Central

    Rebello, Richard J.; Pearson, Richard B.; Hannan, Ross D.; Furic, Luc

    2017-01-01

    The transcript encoding the proto-oncogene MYC is commonly overexpressed in prostate cancer (PC). MYC protein abundance is also increased in the majority of cases of advanced and metastatic castrate-resistant PC (mCRPC). Accordingly, the MYC-directed transcriptional program directly contributes to PC by upregulating the expression of a number of pro-tumorigenic factors involved in cell growth and proliferation. A key cellular process downstream of MYC activity is the regulation of ribosome biogenesis which sustains tumor growth. MYC activity also cooperates with the dysregulation of the phosphoinositol-3-kinase (PI3K)/AKT/mTOR pathway to promote PC cell survival. Recent advances in the understanding of these interactions through the use of animal models have provided significant insight into the therapeutic efficacy of targeting MYC activity by interfering with its transcriptional program, and indirectly by targeting downstream cellular events linked to MYC transformation potential. PMID:28212321

  13. Role of MYC in B Cell Lymphomagenesis.

    PubMed

    Korać, Petra; Dotlić, Snježana; Matulić, Maja; Zajc Petranović, Matea; Dominis, Mara

    2017-04-04

    B cell lymphomas mainly arise from different developmental stages of B cells in germinal centers of secondary lymphoid tissue. There are a number of signaling pathways that affect the initiation and development of B cell lymphomagenesis. The functions of several key proteins that represent branching points of signaling networks are changed because of their aberrant expression, degradation, and/or accumulation, and those events determine the fate of the affected B cells. One of the most influential transcription factors, commonly associated with unfavorable prognosis for patients with B cell lymphoma, is nuclear phosphoprotein MYC. During B cell lymphomagenesis, oncogenic MYC variant is deregulated through various mechanisms, such as gene translocation, gene amplification, and epigenetic deregulation of its expression. Owing to alterations of downstream signaling cascades, MYC-overexpressing neoplastic B cells proliferate rapidly, avoid apoptosis, and become unresponsive to most conventional treatments. This review will summarize the roles of MYC in B cell development and oncogenesis, as well as its significance for current B cell lymphoma classification. We compared communication networks within transformed B cells in different lymphomas affected by overexpressed MYC and conducted a meta-analysis concerning the association of MYC with tumor prognosis in different patient populations.

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

    PubMed

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

    2008-06-01

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

  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. Ribosomal Protein S14 Negatively Regulates c-Myc Activity*

    PubMed Central

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

    2013-01-01

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

  17. 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

  18. De novo MYC addiction as an adaptive response of cancer cells to CDK4/6 inhibition.

    PubMed

    Tarrado-Castellarnau, Míriam; de Atauri, Pedro; Tarragó-Celada, Josep; Perarnau, Jordi; Yuneva, Mariia; Thomson, Timothy M; Cascante, Marta

    2017-10-04

    Cyclin-dependent kinases (CDK) are rational cancer therapeutic targets fraught with the development of acquired resistance by tumor cells. Through metabolic and transcriptomic analyses, we show that the inhibition of CDK4/6 leads to a metabolic reprogramming associated with gene networks orchestrated by the MYC transcription factor. Upon inhibition of CDK4/6, an accumulation of MYC protein ensues which explains an increased glutamine metabolism, activation of the mTOR pathway and blunting of HIF-1α-mediated responses to hypoxia. These MYC-driven adaptations to CDK4/6 inhibition render cancer cells highly sensitive to inhibitors of MYC, glutaminase or mTOR and to hypoxia, demonstrating that metabolic adaptations to antiproliferative drugs unveil new vulnerabilities that can be exploited to overcome acquired drug tolerance and resistance by cancer cells. © 2017 The Authors. Published under the terms of the CC BY 4.0 license.

  19. Arginine methylation regulates c-Myc-dependent transcription by altering promoter recruitment of the acetyltransferase p300.

    PubMed

    Tikhanovich, Irina; Zhao, Jie; Bridges, Brian; Kumer, Sean; Roberts, Ben; Weinman, Steven A

    2017-08-11

    Protein arginine methyltransferase 1 (PRMT1) is an essential enzyme controlling about 85% of the total cellular arginine methylation in proteins. We have shown previously that PRMT1 is an important regulator of innate immune responses and that it is required for M2 macrophage differentiation. c-Myc is a transcription factor that is critical in regulating cell proliferation and also regulates the M2 transcriptional program in macrophages. Here, we sought to determine whether c-Myc in myeloid cells is regulated by PRMT1-dependent arginine methylation. We found that PRMT1 activity was necessary for c-Myc binding to the acetyltransferase p300. PRMT1 inhibition decreased p300 recruitment to c-Myc target promoters and increased histone deacetylase 1 (HDAC1) recruitment, thereby decreasing transcription at these sites. Moreover, PRMT1 inhibition blocked c-Myc-mediated induction of several of its target genes, including peroxisome proliferator-activated receptor γ (PPARG) and mannose receptor C-type 1 (MRC1), suggesting that PRMT1 is necessary for c-Myc function in M2 macrophage differentiation. Of note, in primary human blood monocytes, p300-c-Myc binding was strongly correlated with PRMT1 expression, and in liver sections, PRMT1, c-Myc, and M2 macrophage levels were strongly correlated with each other. Both PRMT1 levels and M2 macrophage numbers were significantly lower in livers from individuals with a history of spontaneous bacterial peritonitis, known to have defective cellular immunity. In conclusion, our findings demonstrate that PRMT1 is an important regulator of c-Myc function in myeloid cells. PRMT1 loss in individuals with cirrhosis may contribute to their immune defects. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

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

    PubMed

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

    2014-04-21

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

  1. Deep Sequencing of MYC DNA-Binding Sites in Burkitt Lymphoma

    PubMed Central

    Seitz, Volkhard; Butzhammer, Peter; Hirsch, Burkhard; Hecht, Jochen; Gütgemann, Ines; Ehlers, Anke; Lenze, Dido; Oker, Elisabeth; Sommerfeld, Anke; von der Wall, Edda; König, Christoph; Zinser, Christian; Spang, Rainer; Hummel, Michael

    2011-01-01

    Background MYC is a key transcription factor involved in central cellular processes such as regulation of the cell cycle, histone acetylation and ribosomal biogenesis. It is overexpressed in the majority of human tumors including aggressive B-cell lymphoma. Especially Burkitt lymphoma (BL) is a highlight example for MYC overexpression due to a chromosomal translocation involving the c-MYC gene. However, no genome-wide analysis of MYC-binding sites by chromatin immunoprecipitation (ChIP) followed by next generation sequencing (ChIP-Seq) has been conducted in BL so far. Methodology/Principal Findings ChIP-Seq was performed on 5 BL cell lines with a MYC-specific antibody giving rise to 7,054 MYC-binding sites after bioinformatics analysis of a total of approx. 19 million sequence reads. In line with previous findings, binding sites accumulate in gene sets known to be involved in the cell cycle, ribosomal biogenesis, histone acetyltransferase and methyltransferase complexes demonstrating a regulatory role of MYC in these processes. Unexpectedly, MYC-binding sites also accumulate in many B-cell relevant genes. To assess the functional consequences of MYC binding, the ChIP-Seq data were supplemented with siRNA- mediated knock-downs of MYC in BL cell lines followed by gene expression profiling. Interestingly, amongst others, genes involved in the B-cell function were up-regulated in response to MYC silencing. Conclusion/Significance The 7,054 MYC-binding sites identified by our ChIP-Seq approach greatly extend the knowledge regarding MYC binding in BL and shed further light on the enormous complexity of the MYC regulatory network. Especially our observations that (i) many B-cell relevant genes are targeted by MYC and (ii) that MYC down-regulation leads to an up-regulation of B-cell genes highlight an interesting aspect of BL biology. PMID:22102868

  2. 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.

  3. Somatic loss of function mutations in neurofibromin 1 and MYC associated factor X genes identified by exome-wide sequencing in a wild-type GIST case.

    PubMed

    Belinsky, Martin G; Rink, Lori; Cai, Kathy Q; Capuzzi, Stephen J; Hoang, Yen; Chien, Jeremy; Godwin, Andrew K; von Mehren, Margaret

    2015-11-10

    Approximately 10-15 % of gastrointestinal stromal tumors (GISTs) lack gain of function mutations in the KIT and platelet-derived growth factor receptor alpha (PDGFRA) genes. An alternate mechanism of oncogenesis through loss of function of the succinate-dehydrogenase (SDH) enzyme complex has been identified for a subset of these "wild type" GISTs. Paired tumor and normal DNA from an SDH-intact wild-type GIST case was subjected to whole exome sequencing to identify the pathogenic mechanism(s) in this tumor. Selected findings were further investigated in panels of GIST tumors through Sanger DNA sequencing, quantitative real-time PCR, and immunohistochemical approaches. A hemizygous frameshift mutation (p.His2261Leufs*4), in the neurofibromin 1 (NF1) gene was identified in the patient's GIST; however, no germline NF1 mutation was found. A somatic frameshift mutation (p.Lys54Argfs*31) in the MYC associated factor X (MAX) gene was also identified. Immunohistochemical analysis for MAX on a large panel of GISTs identified loss of MAX expression in the MAX-mutated GIST and in a subset of mainly KIT-mutated tumors. This study suggests that inactivating NF1 mutations outside the context of neurofibromatosis may be the oncogenic mechanism for a subset of sporadic GIST. In addition, loss of function mutation of the MAX gene was identified for the first time in GIST, and a broader role for MAX in GIST progression was suggested.

  4. 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, Apc Min 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

  5. The relationship between expressions of N-myc and c-myc oncogenes in neuroblastoma: an in situ hybridization and immunocytochemical study.

    PubMed

    Zhe, X; Chen, J; Liu, T; Zhang, L; Li, P; Wang, D

    1999-06-01

    N-myc gene amplification is the most characteristic feature of neuroblastoma. c-myc oncogene, another member of myc gene family, plays an important role in cell proliferation and differentiation. Both of them may contribute to tumorigenesis of neuroblastoma. In this study we use the in situ hybridization and immunocytochemical methods to test the frequencies of N-myc and c-myc expressions in 20 cases of human neuroblastoma at mRNA and protein levels. The positive rates of the expression of N-myc are 90% and 100% detected by in situ hybridization and immunocytochemical methods respectively. The positive rates of c-myc are 80% and 85% respectively. Sixty percent of the 20 specimens tested by in situ hybridization and 55% by immunocytochemistry show an inverse relationship between the expressions of these two oncogenes and this may indicate that there are different gene expression controlling mechanisms in different cases.

  6. Can Genomic Amplification of Human Telomerase Gene and C-MYC in Liquid-Based Cytological Specimens Be Used as a Method for Opportunistic Cervical Cancer Screening?

    PubMed

    Gao, Kun; Eurasian, Menglan; Zhang, Jieqing; Wei, Yuluan; Zheng, Qian; Ye, Hongtao; Li, Li

    2015-01-01

    To evaluate the effectiveness of five methods including the ThinPrep cytological test (TCT), liquid-based cytology, the human papillomavirus (HPV) test, detection of the TERC and C-MYC genes and visual inspection with acetic acid/Lugol's iodine (VIA/VILI) for opportunistic cervical cancer screening, and to explore whether genomic amplification of the human telomerase gene and C-MYC in liquid-based cytological specimens can be used as a method for opportunistic cervical cancer screening. Data were collected prospectively from 1,010 consecutive patients who visited the gynecology clinic and agreed to participate in opportunistic cervical cancer screening at our institution from November 2010 to July 2011. The five methods mentioned above were used for the screening in all cases. The histopathological diagnosis served as the gold standard for the evaluation. A comparison between the five screening methods for the diagnosis of high-grade cervical intraepithelial neoplasia (CIN II and III) was performed for their sensitivity, specificity, false-positive rate, false-negative rate, accuracy rate, positive likelihood ratio and negative likelihood ratio. A comprehensive comparison of the different combination programs for screening was performed according to the analysis of the receiver operating characteristic (ROC) curve area. The accuracy of the five screening methods for the diagnosis of high-grade CIN (CIN II and III) was compared in the different age groups. A joint model for the diagnosis using different combinations of the five methods was developed according to the analysis by the SAS 8.0 software. The model was used to evaluate the accuracy of the different combination programs for the diagnosis of high-grade CIN, and the results were confirmed by the histopathological examination. The sensitivity and specificity of the single screen method (TCT, HPV test, detection of the TERC and C-MYC genes, and VIA/VILI method) for CIN II was 80.9, 70.2, 72.3, 76.6, and 72

  7. RB loss contributes to aggressive tumor phenotypes in MYC-driven triple negative breast cancer.

    PubMed

    Knudsen, Erik S; McClendon, A Kathleen; Franco, Jorge; Ertel, Adam; Fortina, Paolo; Witkiewicz, Agnieszka K

    2015-01-01

    Triple negative breast cancer (TNBC) is characterized by multiple genetic events occurring in concert to drive pathogenic features of the disease. Here we interrogated the coordinate impact of p53, RB, and MYC in a genetic model of TNBC, in parallel with the analysis of clinical specimens. Primary mouse mammary epithelial cells (mMEC) with defined genetic features were used to delineate the combined action of RB and/or p53 in the genesis of TNBC. In this context, the deletion of either RB or p53 alone and in combination increased the proliferation of mMEC; however, the cells did not have the capacity to invade in matrigel. Gene expression profiling revealed that loss of each tumor suppressor has effects related to proliferation, but RB loss in particular leads to alterations in gene expression associated with the epithelial-to-mesenchymal transition. The overexpression of MYC in combination with p53 loss or combined RB/p53 loss drove rapid cell growth. While the effects of MYC overexpression had a dominant impact on gene expression, loss of RB further enhanced the deregulation of a gene expression signature associated with invasion. Specific RB loss lead to enhanced invasion in boyden chambers assays and gave rise to tumors with minimal epithelial characteristics relative to RB-proficient models. Therapeutic screening revealed that RB-deficient cells were particularly resistant to agents targeting PI3K and MEK pathway. Consistent with the aggressive behavior of the preclinical models of MYC overexpression and RB loss, human TNBC tumors that express high levels of MYC and are devoid of RB have a particularly poor outcome. Together these results underscore the potency of tumor suppressor pathways in specifying the biology of breast cancer. Further, they demonstrate that MYC overexpression in concert with RB can promote a particularly aggressive form of TNBC.

  8. Evaluation of Molecular Inhibitors of the c-Myc Oncoprotein

    DTIC Science & Technology

    2007-02-01

    cell lung cancer cells transfected with herpes simplex virus thymidine kinase gene containing Myc-Max response elements. Cancer Res 1996; 56:354–8. 12...I, Perkins RS, Bennett R, Feidler KL, Dunn SP, Krueger LJ. c-Myc inhibition negatively impacts lymphoma growth. J Pediatr Surg 2006;41:207–11. 17. Mo

  9. Cooperation of c-raf-1 and c-myc protooncogenes in the neoplastic transformation of simian virus 40 large tumor antigen-immortalized human bronchial epithelial cells.

    PubMed Central

    Pfeifer, A M; Mark, G E; Malan-Shibley, L; Graziano, S; Amstad, P; Harris, C C

    1989-01-01

    Overexpression of c-raf-1 and the myc family of protooncogenes is primarily associated with small cell carcinoma, which accounts for approximately 25% of human lung cancer. To determine the functional significance of the c-raf-1 and/or c-myc gene expression in lung carcinogenesis and to delineate the relationship between protooncogene expression and tumor phenotype, we introduced both protooncogenes, alone or in combination, into human bronchial epithelial cells. Two retroviral recombinants, pZip-raf and pZip-myc, containing the complete coding sequences of the human c-raf-1 and murine c-myc genes, respectively, were constructed and transfected into simian virus 40 large tumor antigen-immortalized bronchial epithelial cells (BEAS-2B); this was followed by selection for G418 resistance. BEAS-2B cells expressing both the transfected c-raf-1 and c-myc sequences formed large cell carcinomas in athymic nude mice with a latency of 4-21 weeks, whereas either pZip-raf- or pZip-myc-transfected cells were nontumorigenic after 12 months. Cell lines established from tumors (designated RMT) revealed the presence of the cotransfected c-raf-1 and c-myc sequences and expressed morphological, chromosomal, and isoenzyme markers, which identified BEAS-2B cells as the progenitor line of the tumors. A significant increase in the mRNA levels of neuron-specific enolase was detected in BEAS-2B cells containing both the c-raf-1 and c-myc genes and derived tumor cell lines. The data demonstrate that the concomitant expression of the c-raf and c-myc protooncogenes causes neoplastic transformation of human bronchial epithelial cells resulting in large cell carcinomas with certain neuroendocrine markers. The presented model system should be useful in studies of molecular events involved in multistage lung carcinogenesis. Images PMID:2557616

  10. 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.

  11. Detection of C-MYC oncogene translocation and copy number change in the normal-dysplasia-carcinoma sequence of the larynx by fluorescence in situ hybridization.

    PubMed

    Liu, Yu; Gong, Li-Ping; Dong, Xiao-Li; Liu, Hong-Gang

    2013-06-01

    The aim of this study was to determine the translocation and copy number change of the C-MYC gene in patients with laryngeal dysplasia and laryngeal squamous cell carcinoma (LSCC), and to evaluate the prevalence of such expression in relation to the normal-dysplasia-carcinoma sequence. Fluorescent in situ hybridization (FISH) was applied on formalin-fixed paraffin-embedded blocks of 93 laryngeal lesion specimens (14 normal epithelium, 15 mild dysplasia, 18 moderate dysplasia, 16 severe dysplasia, 9 carcinoma in situ, and 21 invasive carcinoma). C-MYC translocation was not observed in all laryngeal tissue. The high frequency for C-MYC copy-number increased (100%) in invasive carcinoma: 57.14% amplifications and 42.86% gains, and the positive rate of C-MYC amplification and copy-number change increased with the increasing severity of laryngeal lesions (P < 0.0001). The results suggest that C-MYC may be activated by gain/amplification in LSCC and precancerous lesions. Thus, C-MYC may play an important role in promoting LSCC progression, and early FISH detection of C-MYC may be exploited to set a screening test for laryngeal dysplasia. Copyright © 2012 Wiley Periodicals, Inc.

  12. High Temperature Induces Expression of Tobacco Transcription Factor NtMYC2a to Regulate Nicotine and JA Biosynthesis

    PubMed Central

    Yang, Liming; Li, Junying; Ji, Jianhui; Li, Ping; Yu, Liangliang; Abd_Allah, Elsayed F.; Luo, Yuming; Hu, Liwei; Hu, Xiangyang

    2016-01-01

    Environmental stress elevates the level of jasmonic acid (JA) and activates the biosynthesis of nicotine and related pyridine alkaloids in tobacco (Nicotiana tabacum L.) by up-regulating the expression of putrescine N-methyltransferase 1 (NtPMT1), which encodes a putrescine N-methyl transferase that catalyzes nicotine formation. The JA signal suppressor JASMONATE ZIM DOMAIN 1 (NtJAZ1) and its target protein, NtMYC2a, also regulate nicotine biosynthesis; however, how these proteins interact to regulate abiotic-induced nicotine biosynthesis is poorly understood. In this study, we found that high-temperature (HT) treatment activated transcription of NtMYC2a, which subsequently stimulated the transcription of genes associated with JA biosynthesis, including Lipoxygenase (LOX), Allene oxide synthase (AOS), Allene oxide cyclase (AOC), and 12-oxophytodienodate reductase (OPR). Overexpression of NtMYC2a increased nicotine biosynthesis by enhancing its binding to the promoter of NtPMT1. Overexpression of either NtJAZ1 or proteasome-resistant NtJAZ1ΔC suppressed nicotine production under normal conditions, but overexpression only of the former resulted in low levels of nicotine under HT treatment. These data suggest that HT induces NtMYC2a accumulation through increased transcription to activate nicotine synthesis; meanwhile, HT-induced NtMYC2a can activate JA synthesis to promote additional NtMYC2a activity by degrading NtJAZ1 at the post-transcriptional level. PMID:27833561

  13. Myc-dependent genome instability and lifespan in Drosophila.

    PubMed

    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.

  14. N-myc regulates growth and fiber cell differentiation in lens development

    PubMed Central

    Cavalheiro, Gabriel R.; Matos-Rodrigues, Gabriel E.; Zhao, Yilin; Gomes, Anielle L.; Anand, Deepti; Predes, Danilo; de Lima, Silmara; Abreu, Jose G.; Zheng, Deyou; Lachke, Salil A.; Cvekl, Ales; Martins, Rodrigo A. P.

    2017-01-01

    Myc proto-oncogenes regulate diverse cellular processes during development, but their roles during morphogenesis of specific tissues are not fully understood. We found that c-myc regulates cell proliferation in mouse lens development and previous genome-wide studies suggested functional roles for N-myc in developing lens. Here, we examined the role of N-myc in mouse lens development. Genetic inactivation of N-myc in the surface ectoderm or lens vesicle impaired eye and lens growth, while "late" inactivation in lens fibers had no effect. Unexpectedly, defective growth of N-myc--deficient lenses was not associated with alterations in lens progenitor cell proliferation or survival. Notably, N-myc-deficient lens exhibited a delay in degradation of DNA in terminally differentiating lens fiber cells. RNA-sequencing analysis of N-myc--deficient lenses identified a cohort of down-regulated genes associated with fiber cell differentiation that included DNaseIIβ. Further, an integrated analysis of differentially expressed genes in N-myc-deficient lens using normal lens expression patterns of iSyTE, N-myc-binding motif analysis and molecular interaction data from the String database led to the derivation of an N-myc-based gene regulatory network in the lens. Finally, analysis of N-myc and c-myc double-deficient lens demonstrated that these Myc genes cooperate to drive lens growth prior to lens vesicle stage. Together, these findings provide evidence for exclusive and cooperative functions of Myc transcription factors in mouse lens development and identify novel mechanisms by which N-myc regulates cell differentiation during eye morphogenesis. PMID:28716713

  15. Targeting MYC Dependence by Metabolic Inhibitors in Cancer.

    PubMed

    Sabnis, Himalee S; Somasagara, Ranganatha R; Bunting, Kevin D

    2017-03-31

    Abstract:MYC is a critical growth regulatory gene that is commonly overexpressed in a wide range of cancers. Therapeutic targeting of MYC transcriptional activity has long been a goal, but it has been difficult to achieve with drugs that directly block its DNA-binding ability. Additional approaches that exploit oncogene addiction are promising strategies against MYC-driven cancers. Also, drugs that target metabolic regulatory pathways and enzymes have potential for indirectly reducing MYC levels. Glucose metabolism and oxidative phosphorylation, which can be targeted by multiple agents, promote cell growth and MYC expression. Likewise, modulation of the signaling pathways and protein synthesis regulated by adenosine monophosphate-activated protein kinase (AMPK) and mechanistic target of rapamycin (mTOR) can also be an effective route for suppressing MYC translation. Furthermore, recent data suggest that metabolism of nucleotides, fatty acids and glutamine are exploited to alter MYC levels. Combination therapies offer potential new approaches to overcome metabolic plasticity caused by single agents. Although potential toxicities must be carefully controlled, new inhibitors currently being tested in clinical trials offer significant promise. Therefore, as both a downstream target of metabolism and an upstream regulator, MYC is a prominent central regulator of cancer metabolism. Exploiting metabolic vulnerabilities of MYC-driven cancers is an emerging research area with translational potential.

  16. c-MYC is required for germinal center selection and cyclic re-entry

    PubMed Central

    Dominguez-Sola, David; Victora, Gabriel D.; Ying, Carol Y.; Phan, Ryan T.; Saito, Masumichi; Nussenzweig, Michel C.; Dalla-Favera, Riccardo

    2013-01-01

    Upon antigenic challenge, B cells enter the dark-zone (DZ) of germinal-centers (GC) to proliferate and hypermutate their immunoglobulin genes. Mutants with increased affinity are positively selected in the light-zone (LZ) to either differentiate into plasma and memory cells, or re-enter the DZ. The molecular circuits governing GC positive selection are not known. We show that the GC reaction requires the biphasic regulation of c-MYC expression, involving its transient induction during early GC commitment, its repression by BCL6 in DZ B cells, and its re-induction in B cells selected for DZ re-entry. Inhibition of MYC in vivo leads to GC collapse, indicating an essential role in GCs. These results have implications for the mechanism of GC selection and the role of MYC in lymphomagenesis. PMID:23001145

  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. © 2016 The Authors. New Phytologist © 2016 New Phytologist Trust.

  18. c-Myc and Her2 cooperate to drive a stem-like phenotype with poor prognosis in breast cancer.

    PubMed

    Nair, R; Roden, D L; Teo, W S; McFarland, A; Junankar, S; Ye, S; Nguyen, A; Yang, J; Nikolic, I; Hui, M; Morey, A; Shah, J; Pfefferle, A D; Usary, J; Selinger, C; Baker, L A; Armstrong, N; Cowley, M J; Naylor, M J; Ormandy, C J; Lakhani, S R; Herschkowitz, J I; Perou, C M; Kaplan, W; O'Toole, S A; Swarbrick, A

    2014-07-24

    The HER2 (ERBB2) and MYC genes are commonly amplified in breast cancer, yet little is known about their molecular and clinical interaction. Using a novel chimeric mammary transgenic approach and in vitro models, we demonstrate markedly increased self-renewal and tumour-propagating capability of cells transformed with Her2 and c-Myc. Coexpression of both oncoproteins in cultured cells led to the activation of a c-Myc transcriptional signature and acquisition of a self-renewing phenotype independent of an epithelial-mesenchymal transition programme or regulation of conventional cancer stem cell markers. Instead, Her2 and c-Myc cooperated to induce the expression of lipoprotein lipase, which was required for proliferation and self-renewal in vitro. HER2 and MYC were frequently coamplified in breast cancer, associated with aggressive clinical behaviour and poor outcome. Lastly, we show that in HER2(+) breast cancer patients receiving adjuvant chemotherapy (but not targeted anti-Her2 therapy), MYC amplification is associated with a poor outcome. These findings demonstrate the importance of molecular and cellular context in oncogenic transformation and acquisition of a malignant stem-like phenotype and have diagnostic and therapeutic consequences for the clinical management of HER2(+) breast cancer.

  19. 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. ©2016 American Association for Cancer Research.

  20. 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

  1. Combined use of nuclear phosphoprotein c-Myc and cellular phosphoprotein p53 for hepatocellular carcinoma detection in high-risk chronic hepatitis C patients.

    PubMed

    Attallah, A M; El-Far, M; Abdelrazek, M A; Omran, M M; Attallah, A A; Elkhouly, A A; Elkenawy, H M; Farid, K

    2017-10-01

    Hepatocellular carcinoma (HCC) is a multistage process resulting from various genetic changes. We aimed to determine nuclear phosphoprotein c-Myc and cellular phosphoprotein p53 expression and to evaluate their importance in HCC diagnosis. One hundred and twenty chronic hepatitis C (CHC) patients (60 non-HCC CHC patients and 60 HCC patients who had a single small (<5 cm) tumour) were recruited. The gene products of c-Myc and p53 were identified in liver tissues and serum samples using immunostaining, western blot and ELISA. Immunohistochemical detection of c-Myc and p53 with monospecific antibodies revealed intense and diffuse cytoplasmic staining patterns. Accumulated mutant proteins, released from tumour cells into the extracellular serum, were detected at 62 KDa, for c-Myc, and 53 KDa, for p53, using western blotting. In contrast to alpha feto-protein, there was a significant increase (p < 0.0001) in the positivity rate of c-Myc (86.7% vs. 6.7%) and p53 (78.3% vs. 8.3%) in the malignant vs. non-malignant patients. The parallel combination of c-Myc and p53 reach the absolute sensitivity (100%), for more accurate and reliable HCC detection (specificity was 87%). c-Myc and p53 are potential HCC diagnostic biomarkers, and convenient combinations of them could improve diagnostic accuracy of HCC.

  2. 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

  3. Myc controls transcriptional regulation of cardiac metabolism and mitochondrial biogenesis in response to pathological stress in mice

    PubMed Central

    Ahuja, Preeti; Zhao, Peng; Angelis, Ekaterini; Ruan, Hongmei; Korge, Paavo; Olson, Aaron; Wang, Yibin; Jin, Eunsook S.; Jeffrey, F. Mark; Portman, Michael; MacLellan, W. Robb

    2010-01-01

    In the adult heart, regulation of fatty acid oxidation and mitochondrial genes is controlled by the PPARγ coactivator–1 (PGC-1) family of transcriptional coactivators. However, in response to pathological stressors such as hemodynamic load or ischemia, cardiac myocytes downregulate PGC-1 activity and fatty acid oxidation genes in preference for glucose metabolism pathways. Interestingly, despite the reduced PGC-1 activity, these pathological stressors are associated with mitochondrial biogenesis, at least initially. The transcription factors that regulate these changes in the setting of reduced PGC-1 are unknown, but Myc can regulate glucose metabolism and mitochondrial biogenesis during cell proliferation and tumorigenesis in cancer cells. Here we have demonstrated that Myc activation in the myocardium of adult mice increases glucose uptake and utilization, downregulates fatty acid oxidation by reducing PGC-1α levels, and induces mitochondrial biogenesis. Inactivation of Myc in the adult myocardium attenuated hypertrophic growth and decreased the expression of glycolytic and mitochondrial biogenesis genes in response to hemodynamic load. Surprisingly, the Myc-orchestrated metabolic alterations were associated with preserved cardiac function and improved recovery from ischemia. Our data suggest that Myc directly regulates glucose metabolism and mitochondrial biogenesis in cardiac myocytes and is an important regulator of energy metabolism in the heart in response to pathologic stress. PMID:20364083

  4. Low-level c-myc amplification in human colonic carcinoma cell lines and tumors: a frequent, p53-independent mutation associated with improved outcome in a randomized multi-institutional trial.

    PubMed

    Augenlicht, L H; Wadler, S; Corner, G; Richards, C; Ryan, L; Multani, A S; Pathak, S; Benson, A; Haller, D; Heerdt, B G

    1997-05-01

    Human colonic cancer is associated with multiple genetic deletions, mutations, and alterations in gene expression; in contrast, gene amplification has not been recognized as a prominent characteristic of human colonic tumors. Although the c-myc gene is overexpressed in approximately 70% of human colonic cancers, previous studies have not detected frequent gene amplification or rearrangement of c-myc in these tumors, although such amplification has been reported in chemically induced rodent colon cancer and quantitative analysis of gene copy number has shown the gene to be amplified at a low level in mucinous and poorly differentiated human colon carcinomas. Using rigorously controlled blot methodology, we have established that the c-myc gene, located at 8q21, exhibited amplification of 87% to 35-fold in 7 of 10 human colonic carcinoma cell lines. This was highly significant even at a low level of amplification in HT29 cells (P < 0.0001). Cytogenetic analysis by G-banding did not detect aneuploidy involving chromsome 8q, suggesting that the amplification for the c-myc gene on 8q was relatively specific, and this was consistent with a lack of amplification detected for the c-mos gene on 8q24, which was assayed similarly. The same methodology then revealed amplification of c-myc from 1.5-fold to 5-fold in 32% of tumors from 149 patients entered into a multi-institutional Phase III study of adjuvant therapy for colon cancer. c-myc status was not related to time to recurrence or death, but low levels of c-myc amplification identified a subset of patients who showed a statistically significant increase in disease-free survival, and a corresponding trend to longer overall survival, in response to adjuvant therapy with 5-fluorouracil plus levamisole. Presence of c-myc amplification was not related to incidence of p53 mutations.

  5. Biological characterization of adult MYC-translocation-positive mature B-cell lymphomas other than molecular Burkitt lymphoma.

    PubMed

    Aukema, Sietse M; Kreuz, Markus; Kohler, Christian W; Rosolowski, Maciej; Hasenclever, Dirk; Hummel, Michael; Küppers, Ralf; Lenze, Dido; Ott, German; Pott, Christiane; Richter, Julia; Rosenwald, Andreas; Szczepanowski, Monika; Schwaenen, Carsten; Stein, Harald; Trautmann, Heiko; Wessendorf, Swen; Trümper, Lorenz; Loeffler, Markus; Spang, Rainer; Kluin, Philip M; Klapper, Wolfram; Siebert, Reiner

    2014-04-01

    Chromosomal translocations affecting the MYC oncogene are the biological hallmark of Burkitt lymphomas but also occur in a subset of other mature B-cell lymphomas. If accompanied by a chromosomal break targeting the BCL2 and/or BCL6 oncogene these MYC translocation-positive (MYC(+)) lymphomas are called double-hit lymphomas, otherwise the term single-hit lymphomas is applied. In order to characterize the biological features of these MYC(+) lymphomas other than Burkitt lymphoma we explored, after exclusion of molecular Burkitt lymphoma as defined by gene expression profiling, the molecular, pathological and clinical aspects of 80 MYC-translocation-positive lymphomas (31 single-hit, 46 double-hit and 3 MYC(+)-lymphomas with unknown BCL6 status). Comparison of single-hit and double-hit lymphomas revealed no difference in MYC partner (IG/non-IG), genomic complexity, MYC expression or gene expression profile. Double-hit lymphomas more frequently showed a germinal center B-cell-like gene expression profile and had higher IGH and MYC mutation frequencies. Gene expression profiling revealed 130 differentially expressed genes between BCL6(+)/MYC(+) and BCL2(+)/MYC(+) double-hit lymphomas. BCL2(+)/MYC(+) double-hit lymphomas more frequently showed a germinal center B-like gene expression profile. Analysis of all lymphomas according to MYC partner (IG/non-IG) revealed no substantial differences. In this series of lymphomas, in which immunochemotherapy was administered in only a minority of cases, single-hit and double-hit lymphomas had a similar poor outcome in contrast to the outcome of molecular Burkitt lymphoma and lymphomas without the MYC break. Our data suggest that, after excluding molecular Burkitt lymphoma and pediatric cases, MYC(+) lymphomas are biologically quite homogeneous with single-hit and double-hit lymphomas as well as IG-MYC and non-IG-MYC(+) lymphomas sharing various molecular characteristics.

  6. Biological characterization of adult MYC-translocation-positive mature B-cell lymphomas other than molecular Burkitt lymphoma

    PubMed Central

    Aukema, Sietse M.; Kreuz, Markus; Kohler, Christian W; Rosolowski, Maciej; Hasenclever, Dirk; Hummel, Michael; Küppers, Ralf; Lenze, Dido; Ott, German; Pott, Christiane; Richter, Julia; Rosenwald, Andreas; Szczepanowski, Monika; Schwaenen, Carsten; Stein, Harald; Trautmann, Heiko; Wessendorf, Swen; Trümper, Lorenz; Loeffler, Markus; Spang, Rainer; Kluin, Philip M.; Klapper, Wolfram; Siebert, Reiner

    2014-01-01

    Chromosomal translocations affecting the MYC oncogene are the biological hallmark of Burkitt lymphomas but also occur in a subset of other mature B-cell lymphomas. If accompanied by a chromosomal break targeting the BCL2 and/or BCL6 oncogene these MYC translocation-positive (MYC+) lymphomas are called double-hit lymphomas, otherwise the term single-hit lymphomas is applied. In order to characterize the biological features of these MYC+ lymphomas other than Burkitt lymphoma we explored, after exclusion of molecular Burkitt lymphoma as defined by gene expression profiling, the molecular, pathological and clinical aspects of 80 MYC-translocation-positive lymphomas (31 single-hit, 46 double-hit and 3 MYC+-lymphomas with unknown BCL6 status). Comparison of single-hit and double-hit lymphomas revealed no difference in MYC partner (IG/non-IG), genomic complexity, MYC expression or gene expression profile. Double-hit lymphomas more frequently showed a germinal center B-cell-like gene expression profile and had higher IGH and MYC mutation frequencies. Gene expression profiling revealed 130 differentially expressed genes between BCL6+/MYC+ and BCL2+/MYC+ double-hit lymphomas. BCL2+/MYC+ double-hit lymphomas more frequently showed a germinal center B-like gene expression profile. Analysis of all lymphomas according to MYC partner (IG/non-IG) revealed no substantial differences. In this series of lymphomas, in which immunochemotherapy was administered in only a minority of cases, single-hit and double-hit lymphomas had a similar poor outcome in contrast to the outcome of molecular Burkitt lymphoma and lymphomas without the MYC break. Our data suggest that, after excluding molecular Burkitt lymphoma and pediatric cases, MYC+ lymphomas are biologically quite homogeneous with single-hit and double-hit lymphomas as well as IG-MYC and non-IG-MYC+ lymphomas sharing various molecular characteristics. PMID:24179151

  7. Molecular cloning of MSSP-2, a c-myc gene single-strand binding protein: characterization of binding specificity and DNA replication activity.

    PubMed Central

    Takai, T; Nishita, Y; Iguchi-Ariga, S M; Ariga, H

    1994-01-01

    We have previously reported the human cDNA encoding MSSP-1, a sequence-specific double- and single-stranded DNA binding protein [Negishi, Nishita, Saëgusa, Kakizaki, Galli, Kihara, Tamai, Miyajima, Iguchi-Ariga and Ariga (1994) Oncogene, 9, 1133-1143]. MSSP-1 binds to a DNA replication origin/transcriptional enhancer of the human c-myc gene and has turned out to be identical with Scr2, a human protein which complements the defect of cdc2 kinase in S.pombe [Kataoka and Nojima (1994) Nucleic Acid Res., 22, 2687-2693]. We have cloned the cDNA for MSSP-2, another member of the MSSP family of proteins. The MSSP-2 cDNA shares highly homologous sequences with MSSP-1 cDNA, except for the insertion of 48 bp coding 16 amino acids near the C-terminus. Like MSSP-1, MSSP-2 has RNP-1 consensus sequences. The results of the experiments using bacterially expressed MSSP-2, and its deletion mutants, as histidine fusion proteins suggested that the binding specificity of MSSP-2 to double- and single-stranded DNA is the same as that of MSSP-1, and that the RNP consensus sequences are required for the DNA binding of the protein. MSSP-2 stimulated the DNA replication of an SV40-derived plasmid containing the binding sequence for MSSP-1 or -2. MSSP-2 is hence suggested to play an important role in regulation of DNA replication. Images PMID:7838710

  8. Reversible linkage of two distinct small molecule inhibitors of Myc generates a dimeric inhibitor with improved potency that is active in myc over-expressing cancer cell lines.

    PubMed

    Wanner, Jutta; Romashko, Darlene; Werner, Douglas S; May, Earl W; Peng, Yue; Schulz, Ryan; Foreman, Kenneth W; Russo, Suzanne; Arnold, Lee D; Pingle, Maneesh; Bergstrom, Donald E; Barany, Francis; Thomson, Stuart

    2015-01-01

    We describe the successful application of a novel approach for generating dimeric Myc inhibitors by modifying and reversibly linking two previously described small molecules. We synthesized two directed libraries of monomers, each comprised of a ligand, a connector, and a bioorthogonal linker element, to identify the optimal dimer configuration required to inhibit Myc. We identified combinations of monomers, termed self-assembling dimeric inhibitors, which displayed synergistic inhibition of Myc-dependent cell growth. We confirmed that these dimeric inhibitors directly bind to Myc blocking its interaction with Max and affect transcription of MYC dependent genes. Control combinations that are unable to form a dimer do not show any synergistic effects in these assays. Collectively, these data validate our new approach to generate more potent and selective inhibitors of Myc by self-assembly from smaller, lower affinity components. This approach provides an opportunity for developing novel therapeutics against Myc and other challenging protein:protein interaction (PPI) target classes.

  9. Reversible Linkage of Two Distinct Small Molecule Inhibitors of Myc Generates a Dimeric Inhibitor with Improved Potency That Is Active in Myc Over-Expressing Cancer Cell Lines

    PubMed Central

    Wanner, Jutta; Romashko, Darlene; Werner, Douglas S.; May, Earl W.; Peng, Yue; Schulz, Ryan; Foreman, Kenneth W.; Russo, Suzanne; Arnold, Lee D.; Pingle, Maneesh; Bergstrom, Donald E.; Barany, Francis; Thomson, Stuart

    2015-01-01

    We describe the successful application of a novel approach for generating dimeric Myc inhibitors by modifying and reversibly linking two previously described small molecules. We synthesized two directed libraries of monomers, each comprised of a ligand, a connector, and a bioorthogonal linker element, to identify the optimal dimer configuration required to inhibit Myc. We identified combinations of monomers, termed self-assembling dimeric inhibitors, which displayed synergistic inhibition of Myc-dependent cell growth. We confirmed that these dimeric inhibitors directly bind to Myc blocking its interaction with Max and affect transcription of MYC dependent genes. Control combinations that are unable to form a dimer do not show any synergistic effects in these assays. Collectively, these data validate our new approach to generate more potent and selective inhibitors of Myc by self-assembly from smaller, lower affinity components. This approach provides an opportunity for developing novel therapeutics against Myc and other challenging protein:protein interaction (PPI) target classes. PMID:25875098

  10. 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

  11. 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. PMID:27382434

  12. C-Myc dysregulation is a co-transforming event for NF-κB activated B-cells.

    PubMed

    David, Amandine; Arnaud, Nicolas; Fradet, Magali; Lascaux, Hélène; Ouk-Martin, Catherine; Gachard, Nathalie; Zimber-Strobl, Ursula; Feuillard, Jean; Faumont, Nathalie

    2017-02-23

    While c-Myc dysregulation is constantly associated with highly proliferating B-cell tumors, NF-κB addiction is found in indolent lymphomas as well as diffuse large B-cell lymphomas either with an activated B-cell like phenotype or associated with Epstein-Barr virus. We raised the question of the effect of c-Myc in B-cells with NF-κB activated by three different inducers: Epstein-Barr Virus-latency III program, TLR-9 and CD40. Induction of c-Myc overexpression increased proliferation of Epstein-Barr Virus-latency III immortalized B-cells, an effect that was dependent on NF-κB. Results from transcriptomic signatures and functional studies showed that c-Myc over-expression increased Epstein-Barr Virus-latency III driven proliferation depending on NF-κB. In vitro, induction of c-Myc increased proliferation of B-cell with TLR9 dependant activation of Myd88, with decreased apoptosis. In the transgenic λc-Myc mouse model with c-Myc over expression in B-cells, in vivo activation of Myd88 by TLR9 induced splenomegaly related to increased S-phase entry of B-cells. Transgenic mice with both continuous CD40 signaling in B-cells and the λc-Myc transgene developed very aggressive lymphomas with characteristics of activated diffuse large B-cell lymphomas. The main characteristic gene expression profile signatures of these tumors were those of proliferation and energetic metabolism. These results suggest that c-Myc is an NF-κB co-transforming event in aggressive lymphomas with an activated phenotype, activated B-cell like diffuse large B-cell lymphomas. This would explain why NF-κB is associated with both indolent and aggressive lymphomas and opens new perspectives on the possibility of combinatory therapies targeting both c-Myc proliferating program and NF-κB activation pathways in diffuse large B-cell lymphomas.

  13. 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

  14. Id2 Is Dispensable for Myc-Induced Epidermal Neoplasia

    PubMed Central

    Murphy, Daniel J.; Swigart, Lamorna Brown; Israel, Mark A.; Evan, Gerard I.

    2004-01-01

    We have previously described a transgenic mouse model of epidermal neoplasia wherein expression of a switchable form of c-Myc, MycERTAM, is targeted to the postmitotic suprabasal keratinocytes of murine epidermis via the involucrin promoter. Sustained activation of c-MycERTAM results in a progressive neoplastic phenotype characterized by aberrant ectopic proliferation and delayed differentiation of suprabasal keratinocytes, culminating in papillomatosis. Transcription of the Id2 gene is regulated by Myc family proteins. Moreover, Id2 is implicated as a pivotal determinant of cell fate in multiple lineages and has a demonstrated role in mediating Myc-dependent cell proliferation in vitro through its interaction with retinoblastoma protein. Using Id2 nullizygous mice, we assessed in vivo the requirement for Id2 in mediating Myc-induced papilloma formation in skin. We show that absence of Id2 has no discernible impact on any measurable attribute of Myc function or on the timing or extent of eventual tumor formation. Thus, our data argue against any essential role for Id2 in mediating Myc action in vivo. PMID:14966287

  15. The activities of MYC, MNT and the MAX-interactome in lymphocyte proliferation and oncogenesis.

    PubMed

    Link, Jason M; Hurlin, Peter J

    2015-05-01

    The MYC family of proteins plays essential roles in embryonic development and in oncogenesis. Efforts over the past 30 years to define the transcriptional activities of MYC and how MYC functions to promote proliferation have produced evolving models of MYC function. One picture that has emerged of MYC and its partner protein MAX is of a transcription factor complex with a seemingly unique ability to stimulate the transcription of genes that are epigenetically poised for transcription and to amplify the transcription of actively transcribed genes. During lymphocyte activation, MYC is upregulated and stimulates a pro-proliferative program in part through the upregulation of a wide variety of metabolic effector genes that facilitate cell growth and cell cycle progression. MYC upregulation simultaneously sensitizes cells to apoptosis and activated lymphocytes and lymphoma cells have pro-survival attributes that allow MYC-driven proliferation to prevail. For example, the MAX-interacting protein MNT is upregulated in activated lymphocytes and was found to protect lymphocytes from MYC-dependent apoptosis. Here we review the activities of MYC, MNT and other MAX interacting proteins in the setting of T and B cell activation and oncogenesis. This article is part of a Special Issue entitled: Myc proteins in cell biology and pathology.

  16. N-myc downstream-regulated gene 2 expression is associated with glucose transport and correlated with prognosis in breast carcinoma

    PubMed Central

    2014-01-01

    Introduction N-myc downstream-regulated gene 2 (NDRG2), a novel tumour suppressor and cell stress-related gene, is involved in many cell metabolic processes, such as hormone, ion and fluid metabolism. We investigated whether NDRG2 is involved in any glucose-dependent energy metabolism, as well as the nature of its correlation with breast carcinoma. Methods The correlations between NDRG2 expression and glucose transporter 1 (GLUT1) expression in clinical breast carcinoma tissues were analysed. The effects of NDRG2 on glucose uptake were assessed in breast cancer cells and xenograft tumours. The consequences of NDRG2-induced regulation of GLUT1 at the transcription and translation levels and the interaction between NDRG2 and GLUT1 were examined. Results Data derived from clinical breast carcinoma specimens revealed that (1) patients with high NDRG2 expression had better disease-free survival and overall survival than those with low NDRG2 expression and (2) NDRG2 expression was negatively correlated with GLUT1 expression in these breast carcinoma tissues. NDRG2 inhibited glucose uptake by promoting GLUT1 protein degradation without affecting GLUT1 transcription in both breast cancer cells and xenograft tumours. In addition, NDRG2 protein interacted and partly colocalised with GLUT1 protein in cell cytoplasm areas. Conclusions The results of our study support the notion that NDRG2 plays an important role in tumour glucose metabolism, in which GLUT1 is a likely candidate contributor to glucose uptake suppression and tumour growth. Targeting the actions of NDRG2 in cell glucose-dependent energy delivery may provide an attractive strategy for therapeutic intervention in human breast carcinoma. PMID:24636131

  17. 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

  18. Direct and indirect targeting of MYC to treat acute myeloid leukemia.

    PubMed

    Brondfield, Sam; Umesh, Sushma; Corella, Alexandra; Zuber, Johannes; Rappaport, Amy R; Gaillard, Coline; Lowe, Scott W; Goga, Andrei; Kogan, Scott C

    2015-07-01

    Acute myeloid leukemia (AML) is the most common acute leukemia in adults and is often resistant to conventional therapies. The MYC oncogene is commonly overexpressed in AML but has remained an elusive target. We aimed to examine the consequences of targeting MYC both directly and indirectly in AML overexpressing MYC/Myc due to trisomy 8/15 (human/mouse), FLT3-ITD mutation, or gene amplification. We performed in vivo knockdown of Myc (shRNAs) and both in vitro and in vivo experiments using four drugs with indirect anti-MYC activity: VX-680, GDC-0941, artemisinin, and JQ1. shRNA knockdown of Myc in mice prolonged survival, regardless of the mechanism underlying MYC overexpression. VX-680, an aurora kinase inhibitor, demonstrated in vitro efficacy against human MYC-overexpressing AMLs regardless of the mechanism of MYC overexpression, but was weakest against a MYC-amplified cell line. GDC-0941, a PI3-kinase inhibitor, demonstrated efficacy against several MYC-overexpressing AMLs, although only in vitro. Artemisinin, an antimalarial, did not demonstrate consistent efficacy against any of the human AMLs tested. JQ1, a bromodomain and extra-terminal bromodomain inhibitor, demonstrated both in vitro and in vivo efficacy against several MYC-overexpressing AMLs. We also confirmed a decrease in MYC levels at growth inhibitory doses for JQ1, and importantly, sensitivity of AML cell lines to JQ1 appeared independent of the mechanism of MYC overexpression. Our data support growing evidence that JQ1 and related compounds may have clinical efficacy in AML treatment regardless of the genetic abnormalities underlying MYC deregulation.

  19. A Novel Intron Element Operates Posttranscriptionally To Regulate Human N-myc Expression

    PubMed Central

    Sivak, Louise E.; Pont-Kingdon, Geneviève; Le, Kim; Mayr, Gabriele; Tai, Kuei-Fang; Stevens, Ben T.; Carroll, William L.

    1999-01-01

    Precisely regulated expression of oncogenes and tumor suppressor genes is essential for normal development, and deregulated expression can lead to cancer. The human N-myc gene normally is expressed in only a subset of fetal epithelial tissues, and its expression is extinguished in all adult tissues except transiently in pre-B lymphocytes. The N-myc gene is overexpressed due to genomic amplification in the childhood tumor neuroblastoma. In previous work to investigate mechanisms of regulation of human N-myc gene expression, we observed that N-myc promoter–chloramphemicol acelyltransferase reporter constructs containing sequences 5′ to exon 1 were active in all cell types examined, regardless of whether endogenous N-myc RNA was detected. In contrast, inclusion of the first exon and a portion of the first intron allowed expression only in those cell types with detectable endogenous N-myc transcripts. We investigated further the mechanisms by which this tissue-specific control of N-myc expression is achieved. Using nuclear run-on analyses, we determined that the N-myc gene is actively transcribed in all cell types examined, indicating a posttranscriptional mode of regulation. Using a series of N-myc intron 1 deletion constructs, we localized a 116-bp element (tissue-specific element [TSE]) within the first intron that directs tissue-specific N-myc expression. The TSE can function independently to regulate expression of a heterologous promoter-reporter minigene in a cell-specific pattern that mirrors the expression pattern of the endogenous N-myc gene. Surprisingly, the TSE can function in both sense and antisense orientations to regulate gene expression. Our data indicate that the human N-myc TSE functions through a posttranscriptional mechanism to regulate N-myc expression. PMID:9858540

  20. Overexpression of c-Myc alters G(1)/S arrest following ionizing radiation.

    PubMed

    Sheen, Joon-Ho; Dickson, Robert B

    2002-03-01

    Study of the mechanism(s) of genomic instability induced by the c-myc proto-oncogene has the potential to shed new light on its well-known oncogenic activity. However, an underlying mechanism(s) for this phenotype is largely unknown. In the present study, we investigated the effects of c-Myc overexpression on the DNA damage-induced G(1)/S checkpoint, in order to obtain mechanistic insights into how deregulated c-Myc destabilizes the cellular genome. The DNA damage-induced checkpoints are among the primary safeguard mechanisms for genomic stability, and alterations of cell cycle checkpoints are known to be crucial for certain types of genomic instability, such as gene amplification. The effects of c-Myc overexpression were studied in human mammary epithelial cells (HMEC) as one approach to understanding the c-Myc-induced genomic instability in the context of mammary tumorigenesis. Initially, flow-cytometric analyses were used with two c-Myc-overexpressing, nontransformed immortal lines (184A1N4 and MCF10A) to determine whether c-Myc overexpression leads to alteration of cell cycle arrest following ionizing radiation (IR). Inappropriate entry into S phase was then confirmed with a bromodeoxyuridine incorporation assay measuring de novo DNA synthesis following IR. Direct involvement of c-Myc overexpression in alteration of the G(1)/S checkpoint was then confirmed by utilizing the MycER construct, a regulatable c-Myc. A transient excess of c-Myc activity, provided by the activated MycER, was similarly able to induce the inappropriate de novo DNA synthesis following IR. Significantly, the transient expression of full-length c-Myc in normal mortal HMECs also facilitated entry into S phase and the inappropriate de novo DNA synthesis following IR. Furthermore, irradiated, c-Myc-infected, normal HMECs developed a sub-G(1) population and a >4N population of cells. The c-Myc-induced alteration of the G(1)/S checkpoint was also compared to the effects of expression of MycS (N

  1. A c-myc antisense oligonucleotide inhibits human retinal pigment epithelial cell proliferation.

    PubMed

    Capeáns, C; Piñeiro, A; Domínguez, F; Loidi, L; Buceta, M; Carneiro, C; Garcia-Caballero, T; Sanchez-Salorio, M

    1998-05-01

    The purpose of this work was to investigate if MYC-dependent intracellular mitogenic pathway is active in cultures of human retinal pigment epithelial (hRPE) cells and whether myc antisense phosphorotioate oligonucleotides (c-myc-AS-ODN) are useful tools for inhibiting the proliferation of hRPE cells. Cultures of hRPE cells were established from adult human corneal donors. These cells were positively stained for cytokeratins and vimentin. Myc mRNA expression was determined by Northern blot analysis and it was determined by means of immunofluorescence if MYC was expressed. C-myc-AS-ODN effect on cell proliferation was estimated by evaluating the incorporation of 5-bromo-2'-deoxy-uridine into cellular DNA. Cell number was estimated by using a tetrazolium bromide based colorimetric method. Human RPE cells in culture expressed MYC and myc mRNA as well as prothymosin alpha mRNA--a gene whose transcription is under MYC control--indicating that MYC-dependent intracellular mitogenic pathway is active in these cells. In accordance with this, we found that blocking the expression of myc by the addition of c-myc-AS-ODN to the culture medium inhibited hRPE cell proliferation. The effect of the c-myc-AS-ODN was found to be sequence specific (the use of a control oligonucleotide with the same sequence but in an opposite direction had no effect) and dose-dependent (4 microM was the lowest effective dose tested). By using RT-PCR we found that the c-myc-AS-ODN inhibition of cell proliferation was related to a diminution in c-myc mRNA expression, and by immunofluorescence we detected a diminution in c-MYC protein staining in RPE cells after 48 hr of treatment with c-myc-AS-ODN. Furthermore, growth inhibition remained for at least 5 days after addition of a single dose of the c-myc-AS-ODN to the culture. We conclude that hRPE cell proliferation is under MYC control. Blocking the expression of myc by c-myc-AS-ODN inhibited hRPE cell proliferation. These findings establish a rationale

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

    PubMed

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

    2012-08-14

    To explore the regulation of p14(ARF) expression and induction of cell apoptosis with the mutant and wild-type c-myc genes in a p53-independent pathway of signal transduction. The mutant and wild-type c-myc genes were transfected by lentivirus into HCC1937 to form the stable over-expression cell lines. Uninfected cells and lentivirus-infected ones carrying no c-myc gene acted as blank and infection controls respectively. And c-myc and p14(ARF) mRNA and protein, proliferation and apoptosis in HCC1937 with mutant and wild-type c-myc were detected by reverse transcription (RT)-PCR, Western blotting, thiazolyl blue tetrazolium bromide (MTT) and terminal deoxynucleotidyl transferase mediated X-dUTP nick end labeling (TUNEL) respectively. After the lentivirus-mediated gene transfer, c-myc mRNA and protein expression increased in the mutant and wild-type groups. p14(ARF) mRNA and protein increased in the wild-type group and the mutant group and there were significant difference between them with blank and infection controls (mutant groups: 0.560 ± 0.010, 0.154 ± 0.011, wild-type groups: 0.651 ± 0.010, 0.382 ± 0.013, both P < 0.05). The group of mutant and wild-type c-myc could promote the proliferation of cell growth. And c-myc was more effective to induce apoptosis in the wild-type group as compared with the mutant group (7.1% ± 0.7% vs 3.2% ± 0.4%, P < 0.05). In a p53-independent pathway, the over-expression of wild-type c-myc obviously up-regulates the expression of p14(ARF). And cell apoptosis may be induced through the regulation of p14(ARF)-related gene, keep balance of proliferative promotion and apoptosis induction. When there is a loss-of-function of mutant c-myc, tumorigenicity increases via a disturbed balance of proliferative promotion and apoptosis induction.

  3. Oligopeptides impairing the Myc-Max heterodimerization inhibit lung cancer cell proliferation by reducing Myc transcriptional activity.

    PubMed

    D'Agnano, Igea; Valentini, Alessandra; Gatti, Giuliana; Chersi, Alberto; Felsani, Armando

    2007-01-01

    Deregulated CMYC gene causes cell transformation and is often correlated with tumor progression and a worse clinical outcome of cancer patients. The transcription factor Myc functions by heterodimerizing with its partner, Max. As a strategy to inhibit Myc activity, we have synthesized three small peptides corresponding to segments of the leucine zipper (LZ) region of Max. The purpose of these peptides is to occupy the site of recognition between Myc and Max located in the LZ and inhibit-specific heterodimerization between these proteins. We have used the synthesized oligopeptides in two lung cancer cell lines with different levels of Myc expression. Results demonstrate that: (i) the three peptides resulted equally effective in competing the interaction between Myc and Max in vitro; (ii) they were efficiently internalized into the cells and significantly inhibited cell growth in the cells showing the highest Myc expression; (iii) one specific peptide, only nine aminoacids long, efficiently impaired the transcriptional activity of Myc in vivo, showing a more stable interaction with this protein. Our results are relevant to the development of novel anti-tumoral therapeutic strategies, directed to Myc-overexpressing tumors.

  4. 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.

  5. Genomic binding by the Drosophila Myc, Max, Mad/Mnt transcription factor network

    PubMed Central

    Orian, Amir; van Steensel, Bas; Delrow, Jeffrey; Bussemaker, Harmen J.; Li, Ling; Sawado, Tomoyuki; Williams, Eleanor; Loo, Lenora W.M.; Cowley, Shaun M.; Yost, Cynthia; Pierce, Sarah; Edgar, Bruce A.; Parkhurst, Susan M.; Eisenman, Robert N.

    2003-01-01

    The Myc/Max/Mad transcription factor network is critically involved in cell behavior; however, there is relatively little information on its genomic binding sites. We have employed the DamID method to carry out global genomic mapping of the Drosophila Myc, Max, and Mad/Mnt proteins. Each protein was tethered to Escherichia coli DNA adenine-methyltransferase (Dam) permitting methylation proximal to in vivo binding sites in Kc cells. Microarray analyses of methylated DNA fragments reveals binding to multiple loci on all major Drosophila chromosomes. This approach also reveals dynamic interactions among network members as we find that increased levels of dMax influence the extent of dMyc, but not dMnt, binding. Computer analysis using the REDUCE algorithm demonstrates that binding regions correlate with the presence of E-boxes, CG repeats, and other sequence motifs. The surprisingly large number of directly bound loci (∼15% of coding regions) suggests that the network interacts widely with the genome. Furthermore, we employ microarray expression analysis to demonstrate that hundreds of DamID-binding loci correspond to genes whose expression is directly regulated by dMyc in larvae. These results suggest that a fundamental aspect of Max network function involves widespread binding and regulation of gene expression. PMID:12695332

  6. Hypoxia-mediated histone acetylation and expression of N-myc transcription factor dictate aggressiveness of neuroblastoma cells.

    PubMed

    Poljaková, Jitka; Groh, Tomáš; Gudino, Zaneta Omana; Hraběta, Jan; Bořek-Dohalská, Lucie; Kizek, René; Doktorová, Helena; Eckschlager, Tomáš; Stiborová, Marie

    2014-04-01

    Cells of solid malignancies generally adapt to entire lack of oxygen. Hypoxia induces the expression of several genes, which allows the cells to survive. For DNA transcription, it is necessary that DNA structure is loosened. In addition to structural characteristics of DNA, its epigenetic alterations influence a proper DNA transcription. Since histones play a key role in epigenetics, changes in expression levels of acetylated histones H3 and H4 as well as of hypoxia-inducible factor-1α (HIF-1α) in human neuroblastoma cell lines cultivated under standard or hypoxic conditions (1% O2) were investigated. Moreover, the effect of hypoxia on the expression of two transcription factors, c-Myc and N-myc, was studied. Hypoxic stress increased levels of acetylated histones H3 and H4 in UKF-NB-3 and UKF-NB-4 neuroblastoma cells with N-myc amplification, whereas almost no changes in acetylation of these histones were found in an SK-N-AS neuroblastoma cell line, the line with diploid N-myc status. An increase in histone H4 acetylation caused by hypoxia in UKF-NB-3 and UKF-NB-4 corresponds to increased levels of N-myc transcription factor in these cells.

  7. MYC2 Differentially Modulates Diverse Jasmonate-Dependent Functions in Arabidopsis[W

    PubMed Central

    Dombrecht, Bruno; Xue, Gang Ping; Sprague, Susan J.; Kirkegaard, John A.; Ross, John J.; Reid, James B.; Fitt, Gary P.; Sewelam, Nasser; Schenk, Peer M.; Manners, John M.; Kazan, Kemal

    2007-01-01

    The Arabidopsis thaliana basic helix-loop-helix Leu zipper transcription factor (TF) MYC2/JIN1 differentially regulates jasmonate (JA)-responsive pathogen defense (e.g., PDF1.2) and wound response (e.g., VSP) genes. In this study, genome-wide transcriptional profiling of wild type and mutant myc2/jin1 plants followed by functional analyses has revealed new roles for MYC2 in the modulation of diverse JA functions. We found that MYC2 negatively regulates Trp and Trp-derived secondary metabolism such as indole glucosinolate biosynthesis during JA signaling. Furthermore, MYC2 positively regulates JA-mediated resistance to insect pests, such as Helicoverpa armigera, and tolerance to oxidative stress, possibly via enhanced ascorbate redox cycling and flavonoid biosynthesis. Analyses of MYC2 cis binding elements and expression of MYC2-regulated genes in T-DNA insertion lines of a subset of MYC2–regulated TFs suggested that MYC2 might modulate JA responses via differential regulation of an intermediate spectrum of TFs with activating or repressing roles in JA signaling. MYC2 also negatively regulates its own expression, and this may be one of the mechanisms used in fine-tuning JA signaling. Overall, these results provide new insights into the function of MYC2 and the transcriptional coordination of the JA signaling pathway. PMID:17616737

  8. A Gly98Val Mutation in the N-Myc Downstream Regulated Gene 1 (NDRG1) in Alaskan Malamutes with Polyneuropathy

    PubMed Central

    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, Øyvind; 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

  9. 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

  10. N-myc downstream regulated gene 1 (NDRG1)/Cap43 enhances portal vein invasion and intrahepatic metastasis in human hepatocellular carcinoma.

    PubMed

    Akiba, Jun; Ogasawara, Sachiko; Kawahara, Akihiko; Nishida, Naoyo; Sanada, Sakiko; Moriya, Fukuko; Kuwano, Michihiko; Nakashima, Osamu; Yano, Hirohisa

    2008-12-01

    N-myc downstream regulated gene 1 (NDRG1)/Cap43 is a 43 kDa protein that is widely distributed in the body. Its expression is regulated by nickel, cobalt, hypoxic condition and others; it is reported to be weaker in tumors than normal tissues; and NDRG1/Cap43 is considered to act suppressively to tumor metastasis. This current study immunohistochemically examined NDRG1/Cap43 expression in hepatocellular carcinoma (HCC), and analyzed its relationship to clinicopathologic factors and prognosis. The samples were 105 surgically resected HCC tissue blocks, i.e., 18 well-differentiated HCC, 61 moderately differentiated HCC, 10 poorly differentiated HCC, 9 'nodule-in-nodule' type HCC, and 7 sarcomatous HCC. In all cases, NDRG1/Cap43 was not expressed in normal liver cells. Strong expression was found in 65 of the 105 cases (62%), i.e., in 11.1% of well-differentiated HCC, 72.1% of moderately differentiated HCC, 80.0% of poorly differentiated HCC, and 71.4% of sarcomatous HCC. In the 'nodule-in-nodule' type, its expression was found in 55.6% of their well-differentiated component, and this frequency was significantly higher than that in well-differentiated HCC (11.1%). In the cases showing strong NDRG1/Cap43 expression, frequency of portal vein invasion and of intrahepatic metastasis was significantly high. No clear relationship between the expression and prognosis was observed. NDRG1/Cap43 expression that was found in advanced HCC was thought to accelerate tumor invasion and metastasis. NDRG1/Cap43 could act as a useful biomarker of HCC.

  11. C-myc proto-oncogene amplification detected by polymerase chain reaction in archival human ovarian carcinomas.

    PubMed Central

    Schreiber, G.; Dubeau, L.

    1990-01-01

    Polymerase chain reaction (PCR) technology was used to examine the state of amplification of the proto-oncogene c-myc in archival ovarian carcinomas. Sequences from the c-myc gene and from a control gene were amplified simultaneously by PCR and the ratios of the two products measured. The results provided an accurate measurement of the relative number of copies of the two genes in each tumor genome if the control and test sequences amplified by PCR were of equal lengths. The results were not affected by the number of PCR cycles used. This technique should facilitate gene amplification studies in clinical medicine. Increased c-myc copy number was found in 17% of the 30 cases examined when a control from the same chromosome as c-myc was used, but in 37% of cases if a control from another chromosome was used. This underlines the importance of the genetic location of the selected control genes for such studies. Images Figure 2 PMID:2205100

  12. N-Myc knockdown and apigenin treatment controlled growth of malignant neuroblastoma cells having N-Myc amplification

    PubMed Central

    Hossain, Md. Motarab; Banik, Naren L.; Ray, Swapan K.

    2013-01-01

    Malignant neuroblastomas mostly occur in children and are frequently associated with N-Myc amplification. Oncogene amplification, which is selective increase in copy number of the oncogene, provides survival advantages in solid tumors including malignant neuroblastoma. We have decreased expression of N-Myc oncogene using short hairpin RNA (shRNA) plasmid to increase anti-tumor efficacy of the isoflavonoid apigenin (APG) in human malignant neuroblastoma SK-N-DZ and SK-N-BE2 cell lines that harbor N-Myc amplification. N-Myc knockdown induced morphological and biochemical features of neuronal differentiation. Combination of N-Myc knockdown and APG most effectively induced morphological and biochemical features of apoptotic death. This combination therapy also prevented cell migration and decreased N-Myc driven survival, angiogenic, and invasive factors. Collectively, N-Myc knockdown and APG treatment is a promising strategy for controlling the growth of human malignant neuroblastoma cell lines that harbor N-Myc amplification. PMID:23941992

  13. c-Myc represses transcription in vivo by a novel mechanism dependent on the initiator element and Myc box II.

    PubMed Central

    Li, L H; Nerlov, C; Prendergast, G; MacGregor, D; Ziff, E B

    1994-01-01

    We show that c-Myc, in addition to activating transcription through E-box Myc binding sites (Ems), also represses transcription by a mechanism dependent on initiator (Inr) elements of the basal promoters of susceptible genes. Repression was first observed as a component of c-Myc biphasic regulation of the adenovirus-2 major late promoter (MLP), which contains both Inr and Ems sequences. Two differentiation-specific genes containing Inr, the C/EBP alpha and albumin genes, are repressed through their basal promoters by c-Myc, but are activated by the related B-HLH-LZ factor, USF. Repression requires both the B-HLH-LZ and Myc box II (MBII) domains. Significantly, a MBII deletion mutant which is deficient in repression, but transactivates normally, fails to cooperate with an activated ras gene to transform primary fibroblasts. Thus Myc-dependent transactivation is insufficient for Ras cooperation and the novel transcription repression function is implicated in Ras cooperation as well as the suppression of Inr-dependent genes. Images PMID:8076602

  14. Intelectin 1 suppresses the growth, invasion and metastasis of neuroblastoma cells through up-regulation of N-myc downstream regulated gene 2.

    PubMed

    Li, Dan; Mei, Hong; Pu, Jiarui; Xiang, Xuan; Zhao, Xiang; Qu, Hongxia; Huang, Kai; Zheng, Liduan; Tong, Qiangsong

    2015-02-21

    Recent studies have revealed the potential roles of intelectin 1 (ITLN1) in tumorigenesis. However, its functions and underlying mechanisms in neuroblastoma (NB), the most common extracranial solid tumor in childhood, still remain largely unknown. Human neuroblastoma cell lines were treated with recombinant ITLN1 protein or stably transfected with ITLN1 expression and short hairpin RNA vectors. Gene expression and signaling pathway were detected by western blot and real-time quantitative RT-PCR. Gene promoter activity and transcription factor binding were detected by luciferase reporter and chromatin immunoprecipitation assays. Growth and aggressiveness of tumor cells were measured by MTT colorimetry, colony formation, scratch assay, matrigel invasion assay, and nude mice model. Mining of public microarray databases revealed that N-myc downstream regulated gene 2 (NDRG2) was significantly correlated with ITLN1 in NB. Gain- and loss-of-function studies indicated that secretory ITLN1 facilitated the NDRG2 expression, resulting in down-regulation of vascular endothelial growth factor (VEGF) and matrix metalloproteinase 9 (MMP-9), in NB cell lines SH-SY5Y, SK-N-BE(2), and SK-N-SH. Krüppel-like factor 4 (KLF4), a transcription factor crucial for NDRG2 expression, was up-regulated by ITLN1 in NB cells via inactivation of phosphoinositide 3-kinase (PI3K)/AKT signaling. Ectopic expression of ITLN1 suppressed the growth, invasion and metastasis of NB cells in vitro and in vivo. Conversely, knockdown of ITLN1 promoted the growth, invasion, and metastasis of NB cells. In addition, rescue experiments in ITLN1 over-expressed or silenced NB cells showed that restoration of NDRG2 expression prevented the tumor cells from ITLN1-mediated changes in these biological features. In clinical NB tissues, ITLN1 was down-regulated and positively correlated with NDRG2 expression. Patients with high ITLN1 or NDRG2 expression had greater survival probability. These findings indicate that

  15. p62/SQSTM1 enhances breast cancer stem-like properties by stabilizing MYC mRNA.

    PubMed

    Xu, L-Z; Li, S-S; Zhou, W; Kang, Z-J; Zhang, Q-X; Kamran, M; Xu, J; Liang, D-P; Wang, C-L; Hou, Z-J; Wan, X-B; Wang, H-J; Lam, E W-F; Zhao, Z-W; Liu, Q

    2017-01-19

    Aberrant p62 overexpression has been implicated in breast cancer development. Here, we found that p62 expression was elevated in breast cancer stem cells (BCSCs), including CD44(+)CD24(-) fractions, mammospheres, ALDH1(+) populations and side population cells. Indeed, short-hairpin RNA (shRNA)-mediated knockdown of p62 impaired breast cancer cells from self-renewing under anchorage-independent conditions, whereas ectopic overexpression of p62 enhanced the self-renewal ability of breast cancer cells in vitro. Genetic depletion of p62 robustly inhibited tumor-initiating frequencies, as well as growth rates of BCSC-derived tumor xenografts in immunodeficient mice. Consistently, immunohistochemical analysis of clinical breast tumor tissues showed that high p62 expression levels were linked to poorer clinical outcome. Further gene expression profiling analysis revealed that p62 was positively correlated with MYC expression level, which mediated the function of p62 in promoting breast cancer stem-like properties. MYC mRNA level was reduced upon p62 deletion by siRNA and increased with p62 overexpression in breast cancer cells, suggesting that p62 positively regulated MYC mRNA. Interestingly, p62 did not transactivate MYC promoter. Instead, p62 delayed the degradation of MYC mRNA by repressing the expression of let-7a and let-7b, thus promoting MYC mRNA stabilization at the post-transcriptional level. Consistently, let-7a and let-7b mimics attenuated p62-mediated MYC mRNA stabilization. Together, these findings unveiled a previously unappreciated role of p62 in the regulation of BCSCs, assigning p62 as a promising therapeutic target for breast cancer treatments.

  16. p62/SQSTM1 enhances breast cancer stem-like properties by stabilizing MYC mRNA

    PubMed Central

    Xu, L-Z; Li, S-S; Zhou, W; Kang, Z-J; Zhang, Q-X; Kamran, M; Xu, J; Liang, D-P; Wang, C-L; Hou, Z-J; Wan, X-B; Wang, H-J; Lam, E W-F; Zhao, Z-W; Liu, Q

    2017-01-01

    Aberrant p62 overexpression has been implicated in breast cancer development. Here, we found that p62 expression was elevated in breast cancer stem cells (BCSCs), including CD44+CD24− fractions, mammospheres, ALDH1+ populations and side population cells. Indeed, short-hairpin RNA (shRNA)-mediated knockdown of p62 impaired breast cancer cells from self-renewing under anchorage-independent conditions, whereas ectopic overexpression of p62 enhanced the self-renewal ability of breast cancer cells in vitro. Genetic depletion of p62 robustly inhibited tumor-initiating frequencies, as well as growth rates of BCSC-derived tumor xenografts in immunodeficient mice. Consistently, immunohistochemical analysis of clinical breast tumor tissues showed that high p62 expression levels were linked to poorer clinical outcome. Further gene expression profiling analysis revealed that p62 was positively correlated with MYC expression level, which mediated the function of p62 in promoting breast cancer stem-like properties. MYC mRNA level was reduced upon p62 deletion by siRNA and increased with p62 overexpression in breast cancer cells, suggesting that p62 positively regulated MYC mRNA. Interestingly, p62 did not transactivate MYC promoter. Instead, p62 delayed the degradation of MYC mRNA by repressing the expression of let-7a and let-7b, thus promoting MYC mRNA stabilization at the post-transcriptional level. Consistently, let-7a and let-7b mimics attenuated p62-mediated MYC mRNA stabilization. Together, these findings unveiled a previously unappreciated role of p62 in the regulation of BCSCs, assigning p62 as a promising therapeutic target for breast cancer treatments. PMID:27345399

  17. ROCK inhibitor reduces Myc-induced apoptosis and mediates immortalization of human keratinocytes

    PubMed Central

    Dakic, Aleksandra; DiVito, Kyle; Fang, Shuang; Suprynowicz, Frank; Gaur, Anirudh; Li, Xin; Palechor-Ceron, Nancy; Simic, Vera; Choudhury, Sujata; Yu, Songtao; Simbulan-Rosenthal, Cynthia M.; Rosenthal, Dean; Schlegel, Richard; Liu, Xuefeng

    2016-01-01

    The Myc/Max/Mad network plays a critical role in cell proliferation, differentiation and apoptosis and c-Myc is overexpressed in many cancers, including HPV-positive cervical cancer cell lines. Despite the tolerance of cervical cancer keratinocytes to high Myc expression, we found that the solitary transduction of the Myc gene into primary cervical and foreskin keratinocytes induced rapid cell death. These findings suggested that the anti-apoptotic activity of E7 in cervical cancer cells might be responsible for negating the apoptotic activity of over-expressed Myc. Indeed, our earlier in vitro studies demonstrated that Myc and E7 synergize in the immortalization of keratinocytes. Since we previously postulated that E7 and the ROCK inhibitor, Y-27632, were members of the same functional pathway in cell immortalization, we tested whether Y-27632 would inhibit apoptosis induced by the over-expression of Myc. Our findings indicate that Y-27632 rapidly inhibited Myc-induced membrane blebbing and cellular apoptosis and, more generally, functioned as an inhibitor of extrinsic and intrinsic pathways of cell death. Most important, Y-27632 cooperated with Myc to immortalize keratinocytes efficiently, indicating that apoptosis is a major barrier to Myc-induced immortalization of keratinocytes. The anti-apoptotic activity of Y-27632 correlated with a reduction in p53 serine 15 phosphorylation and the consequent reduction in the expression of downstream target genes p21 and DAPK1, two genes involved in the induction of cell death. PMID:27556514

  18. Sensitivity to myc-induced apoptosis is retained in spontaneous and transplanted lymphomas of CD2-mycER mice.

    PubMed

    Blyth, K; Stewart, M; Bell, M; James, C; Evan, G; Neil, J C; Cameron, E R

    2000-02-10

    To study the effects of the Myc oncoprotein in a regulatable in vivo system, we generated lines of transgenic mice in which a tamoxifen inducible Myc fusion protein (c-mycER) is expressed under the control of the CD2 locus control region. Activation of the Myc oncoprotein resulted in both proliferation and apoptosis in vivo. Lines with a high transgene copy number developed spontaneous lymphomas at low frequency, but the tumour incidence was significantly increased with tamoxifen treatment. Surprisingly, we found that cellular sensitivity to Myc-induced apoptosis was retained in tumours from these mice and in most lymphoma cell lines, even when null for p53. Resistance to Myc-induced apoptosis could be conferred on these cells by co-expression of Bcl-2. However, acquired resistance is clearly not an obligatory progression event as sensitivity to apoptosis was retained in transplanted tumours in athymic mice. In conclusion, lymphomas arising in CD2-mycER mice retain the capacity to undergo apoptosis in response to Myc activation and show no phenotypic evidence of the presence of an active dominant inhibitor.

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

    PubMed

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

    2004-09-01

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

  20. AMBRA1 links autophagy to cell proliferation and tumorigenesis by promoting c-Myc dephosphorylation and degradation.

    PubMed

    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

    2015-01-01

    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 favours 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.

  1. 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

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

    PubMed Central

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

    2016-01-01

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

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

    PubMed

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

    2017-03-01

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

  4. Myc is a Notch1 transcriptional target and a requisite for Notch1-induced mammary tumorigenesis in mice.

    PubMed

    Klinakis, Apostolos; Szabolcs, Matthias; Politi, Katerina; Kiaris, Hippokratis; Artavanis-Tsakonas, Spyros; Efstratiadis, Argiris

    2006-06-13

    To explore the potential involvement of aberrant Notch1 signaling in breast cancer pathogenesis, we have used a transgenic mouse model. In these animals, mouse mammary tumor virus LTR-driven expression of the constitutively active intracellular domain of the Notch1 receptor (N1(IC)) causes development of lactation-dependent mammary tumors that regress upon gland involution but progress to nonregressing, invasive adenocarcinomas in subsequent pregnancies. Up-regulation of Myc in these tumors prompted a genetic investigation of a potential Notch1/Myc functional relationship in breast carcinogenesis. Conditional ablation of Myc in the mammary epithelium prevented the induction of regressing N1(IC) neoplasms and also reduced the incidence of nonregressing carcinomas, which developed with significantly increased latency. Molecular analyses revealed that both the mouse and human Myc genes are direct transcriptional targets of N1(IC) acting through its downstream Cbf1 transcriptional effector. Consistent with this mechanistic link, Notch1 and Myc expression is positively correlated by immunostaining in 38% of examined human breast carcinomas.

  5. Interferon modulation of c-myc expression in cloned Daudi cells: relationship to the phenotype of interferon resistance.

    PubMed Central

    Dron, M; Modjtahedi, N; Brison, O; Tovey, M G

    1986-01-01

    Treatment of interferon-sensitive Daudi cell with electrophoretically pure human interferon alpha markedly reduced the level of c-myc mRNA, increased the level of class I histocompatibility antigen (HLA) mRNA, and did not affect the level of actin mRNA within the same cells. In contrast, the level of c-myc mRNA or HLA mRNA did not change significantly following interferon treatment in different clones of Daudi cells selected for resistance to the antiproliferative action of interferon. These cells possessed interferon receptors, however, and responded to interferon modulation of other genes, including 2',5' oligoisoadenylate synthetase (M. G. Tovey, M. Dron, K. E. Mogensen, B. Lebleu, N. Metchi, and J. Begon-Lours, Guymarho, J. Gen. Virol., 64:2649-2653, 1983; M. Dron, M. G. Tovey, and P. Eid, J. Gen. Virol., 66:787-795, 1985). A clone of interferon-resistant Daudi cells which had reverted to almost complete sensitivity to both the antiproliferative action of interferon and the interferon-enhanced expression of HLA mRNA remained refractory, however, to interferon modulation of c-myc expression, suggesting that a reduced level of c-myc mRNA may not be a prerequisite for inhibition of cell proliferation in interferon-treated cells. Our results do not exclude the possibility, however, that posttranscriptional modification(s) of c-myc expression may precede an inhibition of cell proliferation in interferon-treated cells. Images PMID:3785169

  6. Interferon modulation of c-myc expression in cloned Daudi cells: relationship to the phenotype of interferon resistance.

    PubMed

    Dron, M; Modjtahedi, N; Brison, O; Tovey, M G

    1986-05-01

    Treatment of interferon-sensitive Daudi cell with electrophoretically pure human interferon alpha markedly reduced the level of c-myc mRNA, increased the level of class I histocompatibility antigen (HLA) mRNA, and did not affect the level of actin mRNA within the same cells. In contrast, the level of c-myc mRNA or HLA mRNA did not change significantly following interferon treatment in different clones of Daudi cells selected for resistance to the antiproliferative action of interferon. These cells possessed interferon receptors, however, and responded to interferon modulation of other genes, including 2',5' oligoisoadenylate synthetase (M. G. Tovey, M. Dron, K. E. Mogensen, B. Lebleu, N. Metchi, and J. Begon-Lours, Guymarho, J. Gen. Virol., 64:2649-2653, 1983; M. Dron, M. G. Tovey, and P. Eid, J. Gen. Virol., 66:787-795, 1985). A clone of interferon-resistant Daudi cells which had reverted to almost complete sensitivity to both the antiproliferative action of interferon and the interferon-enhanced expression of HLA mRNA remained refractory, however, to interferon modulation of c-myc expression, suggesting that a reduced level of c-myc mRNA may not be a prerequisite for inhibition of cell proliferation in interferon-treated cells. Our results do not exclude the possibility, however, that posttranscriptional modification(s) of c-myc expression may precede an inhibition of cell proliferation in interferon-treated cells.

  7. Heart-specific inhibition of protooncogene c-myc attenuates cold-induced cardiac hypertrophy.

    PubMed

    Bello Roufai, M; Li, H; Sun, Z

    2007-10-01

    The protooncogene c-myc is involved in the regulation of cell growth. Although increased c-Myc expression is found in hypertrophied hearts, the role of c-Myc in the development of cardiac hypertrophy (CH) has never been determined. The aim of this study was to test the effect of heart-specific inhibition of c-Myc expression on the development of cold-induced cardiac hypertrophy (CICH). We hypothesized that heart-specific inhibition of c-Myc expression attenuates CICH. We constructed c-Myc antisense (c-MycAS) plasmid and green fluorescent protein (GFP) plasmid driven by a heart-specific promoter, alpha-myosin heavy chain (MHC). The cell culture study indicated that c-MycAS can effectively inhibit c-Myc expression and that GFP can express in the rat heart cells. Four groups of rats were used to test the effect of in vivo inhibition of cardiac c-Myc expression on the development of CICH. Three groups received an intravenous injection of c-MycAS, GFP and buffer, respectively, at the beginning of exposure to moderate cold (6.7 degrees C), while the last group received buffer and was kept at room temperature (25 degrees C) to serve as a control. Blood pressure (BP) of the cold-exposed groups receiving buffer or GFP increased significantly, whereas BP of the c-MycAS group did not increase until 28 days after exposure to cold. Thus, c-MycAS delayed and attenuated cold-induced hypertension (CIH). The antihypertensive effect of c-MycAS was probably due to the decreased cardiac output. Magnetic resonance imaging (MRI) showed that the in vivo left ventricle wall thickness of cold-exposed rats was decreased significantly by c-MycAS. Consistently, the cold-induced increase in heart weight was attenuated by inhibition of cardiac c-Myc expression. The heart specificity of alpha-MHC promoter was confirmed by the selective inhibition of c-Myc expression in the heart and by the selective expression of both GFP mRNA and GFP protein in the heart. Heart-specific inhibition of c-Myc

  8. A pan-cancer analysis of MYC-PVT1 reveals CNV-unmediated deregulation and poor prognosis in renal carcinoma

    PubMed Central

    Posa, Ioana; Carvalho, Silvia; Tavares, Joana; Grosso, Ana Rita

    2016-01-01

    The PVT1 lncRNA has recently been involved in tumorigenesis by affecting the protein stability of the MYC proto-oncogene. Both MYC and PVT1 reside in a well-known cancer-risk locus and enhanced levels of their products have been reported in different human cancers. Nonetheless, the extension and relevance of the MYC-PVT1 deregulation in tumorigenesis has not yet been systematically addressed. Here we performed a pan-cancer analysis of matched copy number, transcriptomic, methylation, proteomic and clinicopathological profiles for almost 7000 patients from 17 different cancers represented in the TCGA cohorts. Among all cancers types, kidney renal clear cell carcinoma (KIRC) showed the strongest upregulation of PVT1 and increased levels of both MYC and PVT1 correlated with the clinical outcome. PVT1 misregulation in KIRC is mostly associated to promoter hypomethylation rather than locus amplification. Furthermore, we found an association between MYC levels and PVT1 expression, which impacted on MYC-target genes. Collectively, our study discloses the role of PVT1 as a novel prognostic factor and as a molecular target for novel therapeutic interventions in renal carcinoma. PMID:27366943

  9. Nucleolar localization of myc transcripts.

    PubMed Central

    Bond, V C; Wold, B

    1993-01-01

    In situ hybridization has revealed a striking subnuclear distribution of c-myc RNA transcripts. A major fraction of the sense-strand nuclear c-myc transcripts was localized to the nucleoli. myc intron 1-containing RNAs were noticeably absent from nucleoli, accumulating instead in the nucleoplasm. The localization of myc RNA to nucleoli was shown to be common to a number of diverse cell types, including primary Sertoli cells and several cell lines. Furthermore, nucleolar localization was not restricted to c-myc and N-myc and myoD transcripts also displayed this phenomenon. In contrast, gamma-actin or lactate dehydrogenase transcripts did not display nucleolar localization. These observations suggest a new role for the nucleolus in transport and/or turnover of potential mRNAs. Images PMID:7684491

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

    SciTech Connect

    Romeo, Megan M.; Ko, Bookyung; Kim, Janice; Brady, Rebecca; Heatley, Hayley C.; He, Jeffrey; Harrod, Carolyn K.; Barnett, Braden; Ratner, Lee; Lairmore, Michael D.; Martinez, Ernest; Lüscher, Bernhard; Robson, Craig N.; Henriksson, Marie; Harrod, Robert

    2015-02-15

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

  11. Myc is required for the maintenance of Kaposi's sarcoma-associated herpesvirus latency.

    PubMed

    Li, Xudong; Chen, Shijia; Feng, Jun; Deng, Hongyu; Sun, Ren

    2010-09-01

    Myc is deregulated by Kaposi's sarcoma-associated herpesvirus (KSHV) latent proteins, but its role in KSHV latency is not clear. We found that Myc knockdown with RNA interference (RNAi) induced KSHV reactivation and increased the protein and mRNA levels of RTA, a key viral regulator of KSHV reactivation. Myc knockdown increased, whereas Myc overexpression inhibited, RTA promoter activity. KSHV reactivation and the activation of the RTA promoter induced by Myc depletion were inhibited by c-Jun N-terminal kinase (JNK) and p38 inhibitors but not by a MEK1 inhibitor. Myc knockdown inhibited primary effusion lymphoma (PEL) cell proliferation through inducing apoptosis and G(1) cell cycle arrest. Thus, Myc may be a key cellular node coupling cellular transformation and KSHV latency.

  12. Small molecules targeting c-Myc oncogene: promising anti-cancer therapeutics.

    PubMed

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

    2014-01-01

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

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

    PubMed Central

    Nguyen, Lynh; Papenhausen, Peter; Shao, Haipeng

    2017-01-01

    c-MYC is one of the most essential transcriptional factors, regulating a diverse array of cellular functions, including proliferation, growth, and apoptosis. Dysregulation of c-MYC is essential in the pathogenesis of a number of B-cell lymphomas, but is rarely reported in T-cell lymphomas. c-MYC dysregulation induces lymphomagenesis by loss of the tight control of c-MYC expression, leading to overexpression of intact c-MYC protein, in contrast to the somatic mutations or fusion proteins seen in many other oncogenes. Dysregulation of c-MYC in B-cell lymphomas occurs either as a primary event in Burkitt lymphoma, or secondarily in aggressive lymphomas such as diffuse large B-cell lymphoma, plasmablastic lymphoma, mantle cell lymphoma, or double-hit lymphoma. Secondary c-MYC changes include gene translocation and gene amplification, occurring against a background of complex karyotype, and most often confer aggressive clinical behavior, as evidenced in the double-hit lymphomas. In low-grade B-cell lymphomas, acquisition of c-MYC rearrangement usually results in transformation into highly aggressive lymphomas, with some exceptions. In this review, we discuss the role that c-MYC plays in the pathogenesis of B-cell lymphomas, the molecular alterations that lead to c-MYC dysregulation, and their effect on prognosis and diagnosis in specific types of B-cell lymphoma. PMID:28379189

  14. Down-regulation of Myc is essential for terminal erythroid maturation.

    PubMed

    Jayapal, Senthil Raja; Lee, Kian Leong; Ji, Peng; Kaldis, Philipp; Lim, Bing; Lodish, Harvey F

    2010-12-17

    Terminal differentiation of mammalian erythroid progenitors involves 4-5 cell divisions and induction of many erythroid important genes followed by chromatin and nuclear condensation and enucleation. The protein levels of c-Myc (Myc) are reduced dramatically during late stage erythroid maturation, coinciding with cell cycle arrest in G(1) phase and enucleation, suggesting possible roles for c-Myc in either or both of these processes. Here we demonstrate that ectopic Myc expression affects terminal erythroid maturation in a dose-dependent manner. Expression of Myc at physiological levels did not affect erythroid differentiation or cell cycle shutdown but specifically blocked erythroid nuclear condensation and enucleation. Continued Myc expression prevented deacetylation of several lysine residues in histones H3 and H4 that are normally deacetylated during erythroid maturation. The histone acetyltransferase Gcn5 was up-regulated by Myc, and ectopic Gcn5 expression partially blocked enucleation and inhibited the late stage erythroid nuclear condensation and histone deacetylation. When overexpressed at levels higher than the physiological range, Myc blocked erythroid differentiation, and the cells continued to proliferate in cytokine-free, serum-containing culture medium with an early erythroblast morphology. Gene expression analysis demonstrated the dysregulation of erythropoietin signaling pathway and the up-regulation of several positive regulators of G(1)-S cell cycle checkpoint by supraphysiological levels of Myc. These results reveal an important dose-dependent function of Myc in regulating terminal maturation in mammalian erythroid cells.

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

    PubMed Central

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

    2014-01-01

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

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

    PubMed

    Nguyen, Lynh; Papenhausen, Peter; Shao, Haipeng

    2017-04-05

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

  17. SmMYC2a and SmMYC2b played similar but irreplaceable roles in regulating the biosynthesis of tanshinones and phenolic acids in Salvia miltiorrhiza

    PubMed Central

    Zhou, Yangyun; Sun, Wei; Chen, Junfeng; Tan, Hexin; Xiao, Ying; Li, Qing; Ji, Qian; Gao, Shouhong; Chen, Li; Chen, Shilin; Zhang, Lei; Chen, Wansheng

    2016-01-01

    Salvia miltiorrhiza Bunge, which contains tanshinones and phenolic acids as major classes of bioactive components, is one of the most widely used herbs in traditional Chinese medicine. Production of tanshinones and phenolic acids is enhanced by methyl jasmonate (MeJA). Transcription factor MYC2 is the switch of jasmontes signaling in plants. Here, we focused on two novel JA-inducible genes in S. miltiorrhiza, designated as SmMYC2a and SmMYC2b, which were localized in the nucleus. SmMYC2a and SmMYC2b were also discovered to interact with SmJAZ1 and SmJAZ2, implying that the two MYC2s might function as direct targets of JAZ proteins. Ectopic RNA interference (RNAi)-mediated knockdown experiments suggested that SmMYC2a/b affected multiple genes in tanshinone and phenolic acid biosynthetic pathway. Besides, the accumulation of tanshinones and phenolic acids was impaired by the loss of function in SmMYC2a/b. Meanwhile, SmMYC2a could bind with an E-box motif within SmHCT6 and SmCYP98A14 promoters, while SmMYC2b bound with an E-box motif within SmCYP98A14 promoter, through which the regulation of phenolic acid biosynthetic pathway might achieve. Together, these results suggest that SmMYC2a and SmMYC2b are JAZ-interacting transcription factors that positively regulate the biosynthesis of tanshinones and Sal B with similar but irreplaceable effects. PMID:26947390

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

    PubMed

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

    2015-04-01

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

  19. B Lymphocyte commitment program is driven by the proto-oncogene c-Myc.

    PubMed

    Vallespinós, Mireia; Fernández, David; Rodríguez, Lorena; Alvaro-Blanco, Josué; Baena, Esther; Ortiz, Maitane; Dukovska, Daniela; Martínez, Dolores; Rojas, Ana; Campanero, Miguel R; Moreno de Alborán, Ignacio

    2011-06-15

    c-Myc, a member of the Myc family of transcription factors, is involved in numerous biological functions including the regulation of cell proliferation, differentiation, and apoptosis in various cell types. Of all of its functions, the role of c-Myc in cell differentiation is one of the least understood. We addressed the role of c-Myc in B lymphocyte differentiation. We found that c-Myc is essential from early stages of B lymphocyte differentiation in vivo and regulates this process by providing B cell identity via direct transcriptional regulation of the ebf-1 gene. Our data show that c-Myc influences early B lymphocyte differentiation by promoting activation of B cell identity genes, thus linking this transcription factor to the EBF-1/Pax-5 pathway.

  20. Compensatory induction of MYC expression by sustained CDK9 inhibition via a BRD4-dependent mechanism

    PubMed Central

    Lu, Huasong; Xue, Yuhua; Yu, Guoying K; Arias, Carolina; Lin, Julie; Fong, Susan; Faure, Michel; Weisburd, Ben; Ji, Xiaodan; Mercier, Alexandre; Sutton, James; Luo, Kunxin; Gao, Zhenhai; Zhou, Qiang

    2015-01-01

    CDK9 is the kinase subunit of positive transcription elongation factor b (P-TEFb) that enables RNA polymerase (Pol) II's transition from promoter-proximal pausing to productive elongation. Although considerable interest exists in CDK9 as a therapeutic target, little progress has been made due to lack of highly selective inhibitors. Here, we describe the development of i-CDK9 as such an inhibitor that potently suppresses CDK9 phosphorylation of substrates and causes genome-wide Pol II pausing. While most genes experience reduced expression, MYC and other primary response genes increase expression upon sustained i-CDK9 treatment. Essential for this increase, the bromodomain protein BRD4 captures P-TEFb from 7SK snRNP to deliver to target genes and also enhances CDK9's activity and resistance to inhibition. Because the i-CDK9-induced MYC expression and binding to P-TEFb compensate for P-TEFb's loss of activity, only simultaneously inhibiting CDK9 and MYC/BRD4 can efficiently induce growth arrest and apoptosis of cancer cells, suggesting the potential of a combinatorial treatment strategy. DOI: http://dx.doi.org/10.7554/eLife.06535.001 PMID:26083714

  1. IS THE AMPLIFICATION OF c-MYC, MLL AND RUNX1 GENES IN AML AND MDS PATIENTS WITH TRISOMY 8, 11 AND 21 A FACTOR FOR A CLONAL EVOLUTION IN THEIR KARYOTYPE?

    PubMed

    Angelova, S; Spassov, B; Nikolova, V; Christov, I; Tzvetkov, N; Simeonova, M

    2015-01-01

    The aim of our study was 1) to define if the amplification of c-MYC, MLL and RUNX1 genes is related to the progressive changes of the karyotype in patients with AML and MDS with trisomy 8, 11 and 21 (+8, +11 and +21) in bone marrow and 2) can that amplification be accepted as part of the clonal evolution (CE). Karyotype analysis was performed in 179 patients with AML or MDS with the different chromosomal aberrations (CA) aged 16-81. The findings were distributed as follow: initiating balanced CA (n = 60), aneuploidia (n = 55), unbalanced CA (n = 64). Amplification of c-MYC, MLL and RUNX1 genes by means of fluorescence in situ hybridization (FISH) was found in 35% (7 out of 20) of AML and MDS patients with +8, +11 u +21 as single CA in their karyotype; in 63.6% of pts (7 out of 11)--with additional numerical or structural CA and in 75% (9 out of 12)--with complex karyotype. We assume that the amplification of the respective chromosomal regions in patients with +8, +11 and +21 is related to CE. Considering the amplification as a factor of CE, we established 3 patterns of karyotype development depending on the type of the initiating CA in it. Significant statistical differences were found between the three patterns regarding the karyotype distribution in the different stages of progression (p < 0.001).

  2. Effects of c-myc expression on cell cycle progression.

    PubMed Central

    Hanson, K D; Shichiri, M; Follansbee, M R; Sedivy, J M

    1994-01-01

    We used targeted homologous recombination to disrupt one c-myc gene copy in a diploid fibroblast cell line and found that a twofold reduction in Myc expression resulted in lower exponential growth rates and a lengthening of the G0-to-S-phase transition (M. Shichiri, K. D. Hanson and J. M. Sedivy, Cell Growth Differ. 4:93-104, 1993). Myc is a transcription factor, and the number of target genes whose regulation could result in differential growth rates may be very large. We have approached this problem by examining effects of reduced c-myc expression in three broad areas: (i) secretion of growth factors, (ii) expression of growth factor receptors, and (iii) intracellular signal transduction between Myc and components of the intrinsic cell cycle clock. We have found no evidence that differential medium conditioning can account for the growth phenotypes. Likewise, the expression of receptors for platelet-derived growth factor, epidermal growth factor, basic fibroblast growth factor, and insulin-like growth factor I was the same in diploid and heterozygous cells (platelet-derived growth factor, epidermal growth factor, fibroblast growth factor, and insulin-like growth factor are the sole growth factors required by these cells for growth in serum-free medium). In contrast, expression of cyclin E, cyclin A, and Rb phosphorylation were delayed when quiescent c-myc heterozygous cells were stimulated to enter the cell cycle. Expression of cyclin D1, cyclin D3, and Cdk2 was not affected. The timing of cyclin E induction was the earliest observable effect of reduced Myc expression. Our data indicate that Myc contributes to regulation of proliferation by a cell-autonomous mechanism that involves the modulation of cyclin E expression and, consequently, progression through the restriction point of the cell cycle. Images PMID:8065309

  3. High p27 protein levels in chronic lymphocytic leukemia are associated to low Myc and Skp2 expression, confer resistance to apoptosis and antagonize Myc effects on cell cycle

    PubMed Central

    Caraballo, Juan M.; Acosta, Juan C.; Cortés, Miguel A.; Albajar, Marta; Gómez-Casares, M. Teresa; Batlle-López, Ana; Cuadrado, M. Angeles; Onaindia, Arantza; Bretones, Gabriel; Llorca, Javier; Piris, Miguel A.; Colomer, Dolors; León, Javier

    2014-01-01

    Myc (c-Myc) counteracts p27 effects, and low p27 usually correlates with high Myc expression in human cancer. However there is no information on the co-expression of both genes in chronic lymphocytic leukemia (CLL). We found a lack of correlation between RNA and protein levels of p27 and Myc in CLL cells, so we determined the protein levels by immunoblot in 107 cases of CLL. We observed a high p27 protein expression in CLL compared to normal B cells. Ectopic p27 expression in a CLL-derived cell line resulted in cell death resistance. Surprisingly, Myc expression was very low or undetectable in most CLL cases analyzed, with a clear correlation between high p27 and low Myc protein levels. This was associated with low Skp2 expression, which is consistent with the Skp2 role in p27 degradation and with SKP2 being a Myc target gene. High Myc expression did not correlate with leukemia progression, despite that cell cycle-related Myc target genes were upregulated. However, biochemical analysis showed that the high p27 levels inhibited cyclin-Cdk complexes even in Myc expressing CLL cells. Our data suggest that the combination of high p27 and low Myc is a marker of CLL cells which is mediated by Skp2. PMID:25051361

  4. Small Molecule Microarrays Enable the Identification of a Selective, Quadruplex-Binding Inhibitor of MYC Expression.

    PubMed

    Felsenstein, Kenneth M; Saunders, Lindsey B; Simmons, John K; Leon, Elena; Calabrese, David R; Zhang, Shuling; Michalowski, Aleksandra; Gareiss, Peter; Mock, Beverly A; Schneekloth, John S

    2016-01-15

    The transcription factor MYC plays a pivotal role in cancer initiation, progression, and maintenance. However, it has proven difficult to develop small molecule inhibitors of MYC. One attractive route to pharmacological inhibition of MYC has been the prevention of its expression through small molecule-mediated stabilization of the G-quadruplex (G4) present in its promoter. Although molecules that bind globally to quadruplex DNA and influence gene expression are well-known, the identification of new chemical scaffolds that selectively modulate G4-driven genes remains a challenge. Here, we report an approach for the identification of G4-binding small molecules using small molecule microarrays (SMMs). We use the SMM screening platform to identify a novel G4-binding small molecule that inhibits MYC expression in cell models, with minimal impact on the expression of other G4-associated genes. Surface plasmon resonance (SPR) and thermal melt assays demonstrated that this molecule binds reversibly to the MYC G4 with single digit micromolar affinity, and with weaker or no measurable binding to other G4s. Biochemical and cell-based assays demonstrated that the compound effectively silenced MYC transcription and translation via a G4-dependent mechanism of action. The compound induced G1 arrest and was selectively toxic to MYC-driven cancer cell lines containing the G4 in the promoter but had minimal effects in peripheral blood mononucleocytes or a cell line lacking the G4 in its MYC promoter. As a measure of selectivity, gene expression analysis and qPCR experiments demonstrated that MYC and several MYC target genes were downregulated upon treatment with this compound, while the expression of several other G4-driven genes was not affected. In addition to providing a novel chemical scaffold that modulates MYC expression through G4 binding, this work suggests that the SMM screening approach may be broadly useful as an approach for the identification of new G4-binding small

  5. MYC/BCL2 double-hit high-grade B-cell lymphoma.

    PubMed

    Li, Shaoying; Lin, Pei; Young, Ken H; Kanagal-Shamanna, Rashmi; Yin, C Cameron; Medeiros, L Jeffrey

    2013-09-01

    Double-hit lymphoma (DHL) has been defined by others as a B-cell lymphoma with MYC/8q24 rearrangement in combination with a translocation involving another gene, such as BCL2, BCL3, or BCL6. The most common form of DHL has translocations involving MYC and BCL2, also known as MYC/BCL2 DHL. In recent years, a number of case series of MYC/BCL2 DHL have been published. Most cases of MYC/BCL2 DHL morphologically resemble diffuse large B-cell lymphoma (DLBCL) or B-cell lymphoma, unclassifiable, with features intermediate between DLBCL and Burkitt lymphoma. These tumors are of B-cell lineage, have a germinal center B-cell immunophenotype with a high proliferation rate, and a complex karyotype. Patients with these tumors have an aggressive clinical course and poor prognosis despite high-intensity chemotherapy. More recently, studies have suggested expanding the spectrum of MYC/BCL2 DHL to include cases that have concurrent MYC and BCL2 cytogenetic abnormalities, but not necessarily translocations. In addition, overexpression of MYC and BCL2 has been shown in an appreciable subset of DLBCL tumors. These tumors show overlap with MYC/BCL2 DHL, but are not equivalent. In this review, we discuss the clinicopathologic, immunophenotypic, cytogenetic, and prognostic features of MYC/BCL2 DHL.

  6. CUDR promotes liver cancer stem cell growth through upregulating TERT and C-Myc

    PubMed Central

    Pu, Hu; Zheng, Qidi; Li, Haiyan; Wu, Mengying; An, Jiahui; Gui, Xin; Li, Tianming; Lu, Dongdong

    2015-01-01

    Cancer up-regulated drug resistant (CUDR) is a novel non-coding RNA gene. Herein, we demonstrate excessive CUDR cooperates with excessive CyclinD1 or PTEN depletion to accelerate liver cancer stem cells growth and liver stem cell malignant transformation in vitro and in vivo. Mechanistically, we reveal the decrease of PTEN in cells may lead to increase binding capacity of CUDR to CyclinD1. Therefore, CUDR-CyclinD1 complex loads onto the long noncoding RNA H19 promoter region that may lead to reduce the DNA methylation on H19 promoter region and then to enhance the H19 expression. Strikingly, the overexpression of H19 increases the binding of TERT to TERC and reduces the interplay between TERT with TERRA, thus enhancing the cell telomerase activity and extending the telomere length. On the other hand, insulator CTCF recruits the CUDR-CyclinD1 complx to form the composite CUDR-CyclinD1-insulator CTCF complex which occupancied on the C-myc gene promoter region, increasing the outcome of oncogene C-myc. Ultimately, excessive TERT and C-myc lead to liver cancer stem cell and hepatocyte-like stem cell malignant proliferation. To understand the novel functions of long noncoding RNA CUDR will help in the development of new liver cancer therapeutic and diagnostic approaches. PMID:26513297

  7. Hepatocyte growth factor-stimulated renal tubular mitogenesis: effects on expression of c-myc, c-fos, c-met, VEGF and the VHL tumour-suppressor and related genes.

    PubMed Central

    Clifford, S. C.; Czapla, K.; Richards, F. M.; O'Donoghue, D. J.; Maher, E. R.

    1998-01-01

    Hepatocyte growth factor (HGF/SF) is a potent renal proximal tubular cell (PTEC) mitogen involved in renal development. HGF/SF is the functional ligand for the c-met proto-oncogene, and germline c-met mutations are associated with familial papillary renal cell carcinoma. Somatic von Hippel-Lindau disease tumour-suppressor gene (VHL) mutations are frequently detected in sporadic clear cell renal cell carcinomas (RCC), and germline VHL mutations are the commonest cause of familial clear cell RCC. pVHL binds to the positive regulatory components of the trimeric elongin (SIII) complex (elongins B and C) and has been observed to deregulate expression of the vascular endothelial growth factor (VEGF) gene. HGF/SF has similarly been reported to up-regulate expression of the VEGF gene in non-renal experimental systems. To investigate the mechanism of HGF/SF action in PTECs and, specifically, to examine potential interactions between the HGF/c-met and the VHL-mediated pathways for renal tubular growth control, we have isolated untransformed PTECs from normal kidneys, developed conditions for their culture in vitro and used these cells to investigate changes in mRNA levels of the VHL, elongin A, B and C, VEGF, c-myc, c-fos and c-met genes after HGF/SF exposure. Significant elevations in the mRNA levels of VEGF, c-myc, c-fos, c-met and elongins A, B and C, but not VHL, were detected after HGF/SF stimulation of human PTECs (P < 0.02), with a consistent order of peak levels observed over successive replicates (c-fos at 1 h, VEGF at 2-4 h, c-