Acetylation of the c-MYC oncoprotein is required for cooperation with the HTLV-1 p30II accessory protein and the induction of oncogenic cellular transformation by p30II/c-MYC

PubMed Central

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

2014-01-01

The human T-cell leukemia retrovirus type-1 (HTLV-1) p30II 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 p30II 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 p30II and c-MYC remain to be completely understood. Herein we demonstrate that p30II induces lysine-acetylation of the c-MYC oncoprotein. Acetylation-defective c-MYC Lys→Arg substitution mutants are impaired for oncogenic transformation with p30II in c-myc−/− HO15.19 fibroblasts. Using dual-chromatin-immunoprecipitations (dual-ChIPs), we further demonstrate that p30II is present in c-MYC-containing nucleoprotein complexes in HTLV-1-transformed HuT-102 T-lymphocytes. Moreover, p30II 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 p30II/c-MYC which could promote proviral replication and contribute to HTLV-1-induced carcinogenesis. PMID:25569455

Effects of C-myc gene silencing on interleukin-1β-induced rat chondrocyte cell proliferation, apoptosis and cytokine expression.

PubMed

Zou, Jian; Li, Xiao-Lin; Shi, Zhong-Min; Xue, Jian-Feng

2018-05-01

This study explores the effects of C-myc gene silencing on cell proliferation, apoptosis and cytokine expression in interleukin (IL)-1β-induced rat chondrocytes. Primary chondrocytes were obtained from 40 Sprague-Dawley rats. For in vitro C-myc3-shRNA transfection, chondrocytes were assigned to a blank 1, model 1, IL-1β + C-myc3-shRNA, C-myc3-shRNA, (IL-1β + C-myc3-shRNA) + C-myc overexpression, C-myc3-shRNA + C-myc overexpression or IL-1β + C-myc-Con group. Western blotting and quantitative real-time polymerase chain reaction (qRT-PCR) were performed to detect C-myc, PCNA and cyclin D1 mRNA and protein expression. Cell proliferation was analyzed via CCK-8 assay and cell cycle while apoptosis was measured through flow cytometry. ELISA was utilized to assess the levels of metallopeptidase 13 (MMP-13), IL-6 and tumor necrosis factor-α (TNF-α). Both the qRT-PCR and Western blotting results demonstrated that C-myc3-shRNA transfection inhibits C-myc expression and promotes PCNA and cyclin D1 expression. In comparison to the model 1 group, all groups except the (IL-1β + C-myc3-shRNA) + C-myc overexpression and IL-1β + C-myc-Con groups showed increases in cell proliferation and S phase cell count and decreases in G 0 /G 1 phase cell count, cell apoptosis and MMP-13, IL-6 and TNF-α levels. The model 1, C-myc3-shRNA and C-myc3-shRNA + C-myc overexpression groups displayed higher cell proliferation and S phase cell count and reduced G 0 /G 1 phase cell count, cell apoptosis and MMP-13, IL-6 and TNF-α levels than the IL-1β + C-myc3-shRNA group. In comparison to the model 1 and C-myc3-shRNA + C-myc overexpression groups, the C-myc3-shRNA group promoted cell proliferation and S phase cell counts but suppressed G 0 /G 1 phase cell count, cell apoptosis and MMP-13, IL-6 and TNF-α levels. In conclusion, the study demonstrates that C-myc gene silencing can promote cell proliferation and inhibit cell apoptosis and cytokine expression in IL-1�

Expression of p27 and c-Myc by immunohistochemistry in breast ductal cancers in African American women.

PubMed

Khan, Farhan; Ricks-Santi, Luisel J; Zafar, Rabia; Kanaan, Yasmine; Naab, Tammey

2018-06-01

Proteins p27 and c-Myc are both key players in the cell cycle. While p27, a tumor suppressor, inhibits progression from G1 to S phase, c-Myc, a proto-oncogene, plays a key role in cell cycle regulation and apoptosis. The objective of our study was to determine the association between expression of c-Myc and the loss of p27 by immunohistochemistry (IHC) in the four major subtypes of breast cancer (BC) (Luminal A, Luminal B, HER2, and Triple Negative) and with other clinicopathological factors in a population of 202 African-American (AA) women. Tissue microarrays (TMAs) were constructed from FFPE tumor blocks from primary ductal breast carcinomas in 202 AA women. Five micrometer sections were stained with a mouse monoclonal antibody against p27 and a rabbit monoclonal antibody against c-Myc. The sections were evaluated for intensity of nuclear reactivity (1-3) and percentage of reactive cells; an H-score was derived from the product of these measurements. Loss of p27 expression and c-Myc overexpression showed statistical significance with ER negative (p < 0.0001), PR negative (p < 0.0001), triple negative (TN) (p < 0.0001), grade 3 (p = 0.038), and overall survival (p = 0.047). There was no statistical significant association between c-Myc expression/p27 loss and luminal A/B and Her2 overexpressing subtypes. In our study, a statistically significant association between c-Myc expression and p27 loss and the triple negative breast cancers (TNBC) was found in AA women. A recent study found that constitutive c-Myc expression is associated with inactivation of the axin 1 tumor suppressor gene. p27 inhibits cyclin dependent kinase2/cyclin A/E complex formation. Axin 1 and CDK inhibitors may represent possible therapeutic targets for TNBC. Copyright © 2018 Elsevier Inc. All rights reserved.

Histopathological and molecular prognostic markers in medulloblastoma: c-myc, N-myc, TrkC, and anaplasia.

PubMed

Eberhart, Charles G; Kratz, John; Wang, Yunyue; Summers, Krista; Stearns, Duncan; Cohen, Kenneth; Dang, Chi V; Burger, Peter C

2004-05-01

Several molecular and histopathological prognostic markers have been proposed for the therapeutic stratification of medulloblastoma patients. Amplification of the c-myc oncogene, elevated levels of c-myc mRNA, or tumor anaplasia have been associated with worse clinical outcomes. In contrast, high TrkC mRNA expression generally presages longer survival. The goal of this study was to evaluate the prognostic value of c-myc, N-myc and TrkC expression in medulloblastomas and compare them to histopathological classification. We used in situ hybridization to measure expression of these molecular markers. c-myc mRNA was detected in 18 of 59 (31%) cases, and was significantly associated with shorter patient survival times on both univariate and multivariate analyses (p = 0.04). The presence of c-myc mRNA was also significantly associated with tumor anaplasia. While survival rates were higher for patients with low N-myc or high TrkC expression, these differences were not statistically significant. The group of patients with either moderate or severely anaplastic tumors showed only a trend towards shorter survival (p = 0.11). However, severe anaplasia alone was significantly prognostic (p = 0.002). Given the prognostic import of c-myc, we investigated 2 potential mechanisms by which its expression might be regulated: Wnt signaling and Mxi-1 mutation. Nuclear translocation of beta-catenin, a marker of Wnt pathway activation, was more common in medulloblastomas with high c-myc than in tumors overall, but the difference was not statistically significant. No Mxi-1 mutations were detected in the 22 cases examined. The association we describe between c-myc expression, tumor anaplasia, and worse clinical outcomes provides further evidence for the importance of this oncogene in medulloblastoma pathobiology.

Activation of protein kinase C induces nuclear translocation of RFX1 and down-regulates c-myc via an intron 1 X box in undifferentiated leukemia HL-60 cells.

PubMed

Chen, L; Smith, L; Johnson, M R; Wang, K; Diasio, R B; Smith, J B

2000-10-13

Treatment of human promyelocytic leukemia cells (HL-60) with phorbol 12-myristate 13-acetate (PMA) is known to decrease c-myc mRNA by blocking transcription elongation at sites near the first exon/intron border. Treatment of HL-60 cells with either PMA or bryostatin 1, which acutely activates protein kinase C (PKC), decreased the levels of myc mRNA and Myc protein. The inhibition of Myc synthesis accounted for the drop in Myc protein, because PMA treatment had no effect on Myc turnover. Treatment with PMA or bryostatin 1 increased nuclear protein binding to MIE1, a c-myc intron 1 element that defines an RFX1-binding X box. RFX1 antiserum supershifted MIE1-protein complexes. Increased MIE1 binding was independent of protein synthesis and abolished by a selective PKC inhibitor, which also prevented the effect of PMA on myc mRNA and protein levels and Myc synthesis. PMA treatment increased RFX1 in the nuclear fraction and decreased it in the cytosol without affecting total RFX1. Transfection of HL-60 cells with myc reporter gene constructs showed that the RFX1-binding X box was required for the down-regulation of reporter gene expression by PMA. These findings suggest that nuclear translocation and binding of RFX1 to the X box cause the down-regulation of myc expression, which follows acute PKC activation in undifferentiated HL-60 cells.

Acute myeloid leukaemia: expression of MYC protein and its association with cytogenetic risk profile and overall survival.

PubMed

Mughal, Muhammad Kashif; Akhter, Ariz; Street, Lesley; Pournazari, Payam; Shabani-Rad, Meer-Taher; Mansoor, Adnan

2017-09-01

Acute myeloid leukaemia (AML) is a clinically aggressive disease with marked genetic heterogeneity. Cytogenetic abnormalities provide the basis for risk stratification into clinically favourable, intermediate, and unfavourable groups. There are additional genetic mutations, which further influence the prognosis of patients with AML. Most of these result in molecular aberrations whose downstream target is MYC. It is therefore logical to study the relationship between MYC protein expression and cytogenetic risk groups. We studied MYC expression by immunohistochemistry in a large cohort (n = 199) of AML patients and correlated these results with cytogenetic risk profile and overall survival (OS). We illustrated differential expression of MYC protein across various cytogenetic risk groups (p = 0.03). Highest expression of MYC was noted in AML patients with favourable cytogenetic risk group. In univariate analysis, MYC expression showed significant negative influence of OS in favourable and intermediate cytogenetic risk group (p = 0.001). Interestingly, MYC expression had a protective effect in the unfavourable cytogenetic risk group. In multivariate analysis, while age and cytogenetic risk group were significant factors influencing survival, MYC expression by immunohistochemistry methods also showed some marginal impact (p = 0.069). In conclusion, we have identified differential expression of MYC protein in relation to cytogenetic risk groups in AML patients and documented its possible impact on OS in favourable and intermediate cytogenetic risk groups. These preliminary observations mandate additional studies to further investigate the routine clinical use of MYC protein expression in AML risk stratification. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

Regulation of c- and N-myc expression during induced differentiation of murine neuroblastoma cells.

PubMed

Larcher, J C; Vayssière, J L; Lossouarn, L; Gros, F; Croizat, B

1991-04-01

Using clones N1E-115 and N1A-103 from mouse neuroblastoma C1300, a comparative analysis of c- and N-myc gene expression was undertaken both in proliferating cells and in cultures exposed to conditions which induce differentiation. Under the latter conditions, while N1E-115 cells extend abundant neurites and express many biochemical features of mature neurons, clone N1A-103 stops dividing and expresses certain neurospecific markers but is unable to differentiate morphologically. In both clones, chemical agents, i.e. 1-methyl cyclohexane carboxylic acid (CCA) or dimethyl sulfoxide (DMSO), induce a decrease in c-myc expression. Similar results were found for N-myc gene in N1E-115 cells, but in contrast, in clone N1A-103, N-myc expression is increased with CCA and not modified with DMSO. Globally, this study favours the hypothesis that changes in c-myc expression would correspond to cell division blockade and differentiation, while modulations in N-myc are more closely related to an early phase of terminal differentiation.

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

PubMed Central

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

2013-01-01

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

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

PubMed

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

2013-10-01

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

Apoptosis and cell proliferation in the development of gastric carcinomas: associations with c-myc and p53 protein expression.

PubMed

Ishii, Hideaki H; Gobé, Glenda C; Pan, Wenshen; Yoneyama, Juichi; Ebihara, Yoshiro

2002-09-01

Patients with gastric carcinomas have a poor prognosis and low survival rates. The aim of the present paper was to characterize cellular and molecular properties to provide insight into aspects of tumor progression in early compared with advanced gastric cancers. One hundred and nine graded gastric carcinomas (early or advanced stage, undifferentiated or differentiated type) with paired non-cancer tissue were studied to define the correlation between apoptosis (morphology, terminal deoxyribonucleotidyl transferase-mediated dUTP-digoxigenin nick end-labeling), cell proliferation (Ki-67 expression, morphology) and expression and localization of two proteins frequently having altered expression in cancers, namely p53 and c-myc. Overall, apoptosis was lower in early stage, differentiated and undifferentiated gastric carcinomas compared with advanced-stage cancers. Cell proliferation was comparatively high in all stages. There was a high level of p53 positivity in all stages. Only the early- and advanced-stage undifferentiated cancers that were p53 positive had a significantly higher level of apoptosis (P < 0.05). Cell proliferation was significantly greater (P < 0.05) only in the early undifferentiated cancers that had either c-myc or p53-positivity. The results indicate that low apoptosis and high cell proliferation combine to drive gastric cancer development. The molecular controls for high cell proliferation of the early stage undifferentiated gastric cancers involve overexpression of both p53 and c-myc. Overexpression of p53 may also control cancer development in that its expression is associated with higher levels of apoptosis in early and late-stage undifferentiated, cancers. Copyright 2002 Blackwell Publishing Asia Pty Ltd

The enforced expression of c-Myc in pig fibroblasts triggers mesenchymal-epithelial transition (MET) via F-actin reorganization and RhoA/Rock pathway inactivation.

PubMed

Shi, Jun-Wen; Liu, Wei; Zhang, Ting-Ting; Wang, Sheng-Chun; Lin, Xiao-Lin; Li, Jing; Jia, Jun-Shuang; Sheng, Hong-Fen; Yao, Zhi-Fang; Zhao, Wen-Tao; Zhao, Zun-Lan; Xie, Rao-Ying; Yang, Sheng; Gao, Fei; Fan, Quan-Rong; Zhang, Meng-Ya; Yue, Min; Yuan, Jin; Gu, Wei-Wang; Yao, Kai-Tai; Xiao, Dong

2013-04-01

In previous studies from other labs it has been well demonstrated that the ectopic expression of c-Myc in mammary epithelial cells can induce epithelial-mesenchymal transition (EMT), whereas in our pilot experiment, epithelial-like morphological changes were unexpectedly observed in c-Myc-expressing pig fibroblasts [i.e., porcine embryonic fibroblasts (PEFs) and porcine dermal fibroblasts (PDFs)] and pig mesenchymal stem cells, suggesting that the same c-Myc gene is entitled to trigger EMT in epithelial cells and mesenchymal-epithelial transition (MET) in fibroblasts. This prompted us to characterize the existence of a MET in c-Myc-expressing PEFs and PDFs at the molecular level. qRT-PCR, immunofluorescence and western blot analysis illustrated that epithelial-like morphological changes were accompanied by the increased expression of epithelial markers [such as cell adhesion proteins (E-cadherin, α-catenin and Bves), tight junction protein occludin and cytokeratins (Krt8 and Krt18)], the reduced expression of mesenchymal markers [vimentin, fibronectin 1 (FN1), snail1, collagen family of proteins (COL1A1, COL5A2) and matrix metalloproteinase (MMP) family (MMP12 and MMP14)] and the decreased cell motility and increased cell adhesion in c-Myc-expressing PEFs and PDFs. Furthermore, the ectopic expression of c-Myc in pig fibroblasts disrupted the stress fiber network, suppressed the formation of filopodia and lamellipodia, and resulted in RhoA/Rock pathway inactivation, which finally participates in epithelial-like morphological conversion. Taken together, these findings demonstrate, for the first time, that the enforced expression of c-Myc in fibroblasts can trigger MET, to which cytoskeleton depolymerization and RhoA/Rock pathway inactivation contribute.

HSP-70, C-myc and HLA-DR expression in patients with cutaneous malignant melanoma metastatic in lymph nodes.

PubMed

Kalogeraki, A; Garbagnati, F; Darivianaki, K; Delides, G S; Santinami, M; Stathopoulos, E N; Zoras, O

2006-01-01

HSP-70, C-myc and HLA-DR were examined in patients with cutaneous malignant melanoma metastatic to lymph nodes. Lymph-nodal fine-needle aspiration biopsies (FNABs) were analyzed and the results were correlated to other variables, such as the gender of the patients, Clark level and Breslow thickness of the primary tumor. Thirty cases of metastatic melanoma in lymph nodes from 30 patients with cutaneous malignant melanoma were studied. All patients (100%) had microscopic regional nodal metastasis and a recurrence of the lesion during the first two years. The HSP-70, C-myc and HLA-DR expressions were investigated immunocytologically, using the APAAP (alkaline phosphatase) method on the FNAB samples. The immunocytochemical expressions of HSP-70 protein, C-myc oncogene, and HLA-DR antigen were found in 18 cases (60%), in 14 cases (43.3%) and in 12 cases (40%), respectively. Clark levels were significantly associated with HSP-70 protein (< 0.01), C-myc oncogene expression (< 0.05) and HLA-DR antigen (< 0.01) expression. The HLA-DR antigen was also found to be related (< 0.05) to higher Breslow thickness (> 1.5 mm). The clinical course of malignant cutaneous melanoma is related to the expression of these indices, which seem to play a significant role in the metastasis and prognosis of this aggressive tumor. The immunocytochemical expression of HSP-70 in the malignant melanoma tumor could be of particular value in the identification of patients with poor prognosis.

Nuclear C-MYC expression level is associated with disease progression and potentially predictive of two year overall survival in prostate cancer.

PubMed

Zeng, Wen; Sun, Hanying; Meng, Fankai; Liu, Zeming; Xiong, Jing; Zhou, Sheng; Li, Fan; Hu, Jia; Hu, Zhiquan; Liu, Zheng

2015-01-01

Upregulation of nuclear C-MYC protein has been reported to be an early event in prostate cancer (PCa); however, its clinicopathological and prognostic significance remain controversial. We determined the association of nuclear C-MYC protein expression with clinicopathological parameters, prognosis, ETS-related gene (ERG) expression, and TMPRSS2-ERG status in PCa. Nuclear C-MYC and ERG expression by immunohistochemistry and TMPRSS2-ERG status by triple-color probe fluorescence in situ hybridization assay were determined in 50 hormone-naïve PCa patients and 31 radical prostatectomy specimens. Nuclear C-MYC immunostaining was negative, positive, and strong positive in 27.5%, 32.5%, and 40.0% of cases, respectively. C-MYC immunostaining was significantly associated with clinical T stage (P < 0.001), distant metastasis at the time of diagnosis (P < 0.001) and TMPRSS2-ERG status (P = 0.001) but not with ERG immunostaining (P = 0.818). In the Kaplan-Meier analysis, C-MYC positive cases were found to have worse 2-year OS compared with C-MYC negative cases (P = 0.027). However, in the univariate Cox analysis, only TMPRSS2-ERG status (hazard ratio [HR] 0.189, 95% CI 0.057-0.629; P = 0.007) and distant metastasis (HR 3.545, 95% CI 1.056-11.894; P = 0.040) were significantly associated with 2-year OS. After adjusting for these two factors, TMPRSS2-ERG status still impacted 2-year OS (HR 0.196, 95% CI 0.049-0.778; P = 0.020). Nuclear C-MYC overexpression may be associated with disease progression and potentially predictive of 2-year OS in PCa. This is the first study to demonstrate an association between nuclear C-MYC immunostaining and TMPRSS2-ERG status in PCa.

Tyrosine kinase oncogenes abrogate interleukin-3 dependence of murine myeloid cells through signaling pathways involving c-myc: conditional regulation of c-myc transcription by temperature-sensitive v-abl.

PubMed Central

Cleveland, J L; Dean, M; Rosenberg, N; Wang, J Y; Rapp, U R

1989-01-01

Retroviral expression vectors carrying the tyrosine kinase oncogenes abl, fms, src, and trk abrogate the requirements of murine myeloid FDC-P1 cells for interleukin-3 (IL-3). Factor-independent clones constitutively express c-myc in the absence of IL-3, whereas in parental cultures c-myc transcription requires the presence of the ligand. To directly test the effect of a tyrosine kinase oncogene on c-myc expression, retroviral constructs containing three different temperature-sensitive mutants of v-abl were introduced into myeloid IL-3-dependent FDC-P1 and 32D cells. At the permissive temperature, clones expressing temperature-sensitive abl behaved like wild-type abl-containing cells in their growth properties and expressed c-myc constitutively. Temperature shift experiments demonstrated that both IL-3 abrogation and the regulation of c-myc expression correlated with the presence of functional v-abl. Induction of c-myc expression by reactivation of temperature-sensitive v-abl mimicked c-myc induction by IL-3 in that it did not require protein synthesis and occurred at the level of transcription, with effects on both initiation and a transcription elongation block. However, v-abl-regulated FDC-P1 cell growth differed from IL-3-regulated growth in that c-fos and junB, which are normally induced by IL-3, were not induced by activation of v-abl. Images PMID:2555703

Cellular MYCro economics: Balancing MYC function with MYC expression.

PubMed

Levens, David

2013-11-01

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

Differential cellular responses by oncogenic levels of c-Myc expression in long-term confluent retinal pigment epithelial cells.

PubMed

Wang, Yiping; Cheng, Xiangdong; Samma, Muhammad Kaleem; Kung, Sam K P; Lee, Clement M; Chiu, Sung Kay

2018-06-01

c-Myc is a highly pleiotropic transcription factor known to control cell cycle progression, apoptosis, and cellular transformation. Normally, ectopic expression of c-Myc is associated with promoting cell proliferation or triggering cell death via activating p53. However, it is not clear how the levels of c-Myc lead to different cellular responses. Here, we generated a series of stable RPE cell clones expressing c-Myc at different levels, and found that consistent low level of c-Myc induced cellular senescence by activating AP4 in post-confluent RPE cells, while the cells underwent cell death at high level of c-Myc. In addition, high level of c-Myc could override the effect of AP4 on cellular senescence. Further knockdown of AP4 abrogated senescence-like phenotype in cells expressing low level of c-Myc, and accelerated cell death in cells with medium level of c-Myc, indicating that AP4 was required for cellular senescence induced by low level of c-Myc.

Exon 2-mediated c-myc mRNA decay in vivo is independent of its translation.

PubMed Central

Pistoi, S; Roland, J; Babinet, C; Morello, D

1996-01-01

We have previously shown that the steady-state level of c-myc mRNA in vivo is primarily controlled by posttranscriptional regulatory mechanisms. To identify the sequences involved in this process, we constructed a series of H-2/myc transgenic lines in which various regions of the human c-MYC gene were placed under the control of the quasi-ubiquitous H-2K class I regulatory sequences. We demonstrated that the presence of one of the two coding exons, exon 2 or exon 3, is sufficient to confer a level of expression of transgene mRNA similar to that of endogenous c-myc in various adult tissues as well as after partial hepatectomy or after protein synthesis inhibition. We now focus on the molecular mechanisms involved in modulation of expression of mRNAs containing c-myc exon 2 sequences, with special emphasis on the coupling between translation and c-myc mRNA turnover. We have undertaken an analysis of expression, both at the mRNA level and at the protein level, of new transgenic constructs in which the translation is impaired either by disruption of the initiation codon or by addition of stop codons upstream of exon 2. Our results show that the translation of c-myc exon 2 is not required for regulated expression of the transgene in the different situations analyzed, and therefore they indicate that the mRNA destabilizing function of exon 2 is independent of translation by ribosomes. Our investigations also reveal that, in the thymus, some H-2/myc transgenes express high levels of mRNA but low levels of protein. Besides the fact that these results suggest the existence of tissue-specific mechanisms that control c-myc translatability in vivo, they also bring another indication of the uncoupling of c-myc mRNA translation and degradation. PMID:8756668

Macrocyclic peptides decrease c-Myc protein levels and reduce prostate cancer cell growth.

PubMed

Mukhopadhyay, Archana; Hanold, Laura E; Thayele Purayil, Hamsa; Gisemba, Solomon A; Senadheera, Sanjeewa N; Aldrich, Jane V

2017-08-03

The oncoprotein c-Myc is often overexpressed in cancer cells, and the stability of this protein has major significance in deciding the fate of a cell. Thus, targeting c-Myc levels is an attractive approach for developing therapeutic agents for cancer treatment. In this study, we report the anti-cancer activity of the macrocyclic peptides [D-Trp]CJ-15,208 (cyclo[Phe-D-Pro-Phe-D-Trp]) and the natural product CJ-15,208 (cyclo[Phe-D-Pro-Phe-Trp]). [D-Trp]CJ-15,208 reduced c-Myc protein levels in prostate cancer cells and decreased cell proliferation with IC 50 values ranging from 2.0 to 16 µM in multiple PC cell lines. [D-Trp]CJ-15,208 induced early and late apoptosis in PC-3 cells following 48 hours treatment, and growth arrest in the G2 cell cycle phase following both 24 and 48 hours treatment. Down regulation of c-Myc in PC-3 cells resulted in loss of sensitivity to [D-Trp]CJ-15,208 treatment, while overexpression of c-Myc in HEK-293 cells imparted sensitivity of these cells to [D-Trp]CJ-15,208 treatment. This macrocyclic tetrapeptide also regulated PP2A by reducing the levels of its phosphorylated form which regulates the stability of cellular c-Myc protein. Thus [D-Trp]CJ-15,208 represents a new lead compound for the potential development of an effective treatment of prostate cancer.

Targeting c-Myc: JQ1 as a promising option for c-Myc-amplified esophageal squamous cell carcinoma.

PubMed

Wang, Jingyuan; Liu, Zhentao; Wang, Ziqi; Wang, Shubin; Chen, Zuhua; Li, Zhongwu; Zhang, Mengqi; Zou, Jianling; Dong, Bin; Gao, Jing; Shen, Lin

2018-04-10

c-Myc amplification-induced cell cycle dysregulation is a common cause for esophageal squamous cell carcinoma (ESCC), but no approved targeted drug is available so far. The bromodomain inhibitor JQ1, which targets c-Myc, exerts anti-tumor activity in multiple cancers. However, the role of JQ1 in ESCC remains unknown. In this study, we reported that JQ1 had potent anti-proliferative effects on ESCC cells in both time- and dose-dependent manners by inducing cell cycle arrest at G1 phase, cell apoptosis, and the mesenchymal-epithelial transition. Follow-up studies revealed that both c-Myc/cyclin/Rb and PI3K/AKT signaling pathways were inactivated by JQ1, as indicated by the downregulation of c-Myc, cyclin A/E, and phosphorylated Rb, AKT and S6. Tumor suppression induced by JQ1 in c-Myc amplified or highly expressed xenografts was higher than that in xenografts with low expression, suggesting its potential role in prediction. In conclusion, targeting c-Myc by JQ1 could cause significant tumor suppression in ESCC both in vitro and in vivo. Also, c-Myc amplification or high expression might serve as a potential biomarker and provide a promising therapeutic option for ESCC. Copyright © 2018 Elsevier B.V. All rights reserved.

Dual expression of MYC and BCL2 proteins predicts worse outcomes in diffuse large B-cell lymphoma.

PubMed

Clark Schneider, Kelli M; Banks, Peter M; Collie, Angela M B; Lanigan, Christopher P; Manilich, Elena; Durkin, Lisa M; Hill, Brian T; Hsi, Eric D

2016-07-01

Recent studies suggested that MYC and BCL2 protein co-expression is an independent indicator of poor prognosis in diffuse large B-cell lymphoma. However, the immunohistochemistry protocols for dual-expression staining and the scoring cut-offs vary by study. Sixty-nine cases of diffuse large B-cell lymphoma were evaluated for MYC and BCL2 protein expression using various cut-offs that have been recommended in prior studies. Independent of the International Prognostic Index risk group, cases with dual protein expression of BCL2 and MYC using ≥50%/40% cut-offs and ≥70%/40% had significantly shorter overall survival than cases without. It was verified in this patient population that the use of BCL2 and MYC immunohistochemistry, performed with available in vitro diagnostic-cleared antibodies, provides rapid prognostic information in patients with de novo diffuse large B-cell lymphoma. This study has practical implications for diagnostic laboratories and serves as a guide for implementation in the setting of future clinical trials.

Decline in c-myc mRNA expression but not the induction of c-fos mRNA expression is associated with differentiation of SH-SY5Y human neuroblastoma cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jalava, A.M.; Heikkilae, J.E.; Akerman, K.E.O.

1988-11-01

The induction of differentiation in SH-SY5Y human neuroblastoma cells with 12-O-tetradecanoylphorbol-13-acetate (TPA) is accompanied by a rapid and a transient expression of c-fos mRNA and a down-regulation of c-myc RNA. The TPA-induced expression of c-fos mRNA was inhibited by H-7, a specific inhibitor of protein kinase C (PK-C). Dioctanoylglycerol (DiC{sub 8}) failed to induce differentiation of SH-SY5Y cells or to down-regulate c-myc mRNA but it did induce the expression of c-fos mRNA. Treatment of IMR-32 human neuroblastoma cells with TPA did not cause differentiation although c-fos mRNA was induced. Since PK-C in SH-SY5Y cells was activated by both TPA andmore » DiC{sub 8} it is suggested that the activation of PK-C alone is not sufficient to induce differentiation in SH-SY5Y cells. The down-regulation of c-myc mRNA rather than the induction of c-fos mRNA seems to be associated with differentiation process in SH-SY5Y cells.« less

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

PubMed Central

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

2015-01-01

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

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

DTIC Science & Technology

1997-09-01

including those of the Myc family. In fact, members of different bHLH protein subgroups, including the Myc proteins, are characterized by conserved BR...important functional consequences, and they provide insights into how different bHLH proteins can act on different targets. The zinc finger protein...roles for a number of BR residues which do not contact bases, yet are conserved within different bHLH protein sub- families (Benezra et al. 1990), and

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

Lack of induction of tissue transglutaminase but activation of the preexisting enzyme in c-Myc-induced apoptosis of CHO cells.

PubMed

Balajthy, Z; Kedei, N; Nagy, L; Davies, P J; Fésüs, L

1997-07-18

The intracellular activity and expression of tissue transglutaminase, which crosslinks proteins through epsilon(gamma-glutamyl)lysine isodipeptide bond, was investigated in CHO cells and those stably transfected with either inducible c-Myc (which leads to apoptosis) or with c-myc and the apoptosis inhibitor Bcl-2. Protein-bound cross-link content was significantly higher when apoptosis was induced by c-Myc while the concomitant presence of Bcl-2 markedly reduced both apoptosis and enzymatic protein cross-linking. The expression of tissue transglutaminase did not change following the initiation of apoptosis by c-Myc or when it was blocked by Bcl-2. Studying transiently co-transfected elements of the mouse tissue transglutaminase promoter linked to a reporter enzyme revealed their overall repression in cells expressing c-Myc. This repression was partially suspended in cells also carrying Bcl-2. Our data suggest that tissue transglutaminase is not induced when c-Myc initiates apoptosis but the pre-existing endogenous enzyme is activated.

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

PubMed Central

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

2010-01-01

Human (h) induced pluripotent stem cells (iPSCs) are a potentially abundant source of blood cells, but how best to select iPSC clones suitable for this purpose from among the many clones that can be simultaneously established from an identical source is not clear. Using an in vitro culture system yielding a hematopoietic niche that concentrates hematopoietic progenitors, we show that the pattern of c-MYC reactivation after reprogramming influences platelet generation from hiPSCs. During differentiation, reduction of c-MYC expression after initial reactivation of c-MYC expression in selected hiPSC clones was associated with more efficient in vitro generation of CD41a+CD42b+ platelets. This effect was recapitulated in virus integration-free hiPSCs using a doxycycline-controlled c-MYC expression vector. In vivo imaging revealed that these CD42b+ platelets were present in thrombi after laser-induced vessel wall injury. In contrast, sustained and excessive c-MYC expression in megakaryocytes was accompanied by increased p14 (ARF) and p16 (INK4A) expression, decreased GATA1 expression, and impaired production of functional platelets. These findings suggest that the pattern of c-MYC expression, particularly its later decline, is key to producing functional platelets from selected iPSC clones. PMID:21098095

Suppression of Myc oncogenic activity by ribosomal protein haploinsufficiency

PubMed Central

Barna, Maria; Pusic, Aya; Zollo, Ornella; Costa, Maria; Kondrashov, Nadya; Rego, Eduardo; Rao, Pulivarthi H; Ruggero, Davide

2008-01-01

The Myc oncogene regulates the expression of multiple components of the protein synthetic machinery, including ribosomal proteins, initiation factors of translation, Pol III, and rDNA1,2. An outstanding question is whether and how increasing the cellular protein synthesis capacity can affect the multi-step process leading to cancer. We utilized ribosomal protein heterozygote mice as a genetic tool to restore increased protein synthesis in Eμ–Myc/+ transgenic mice to normal levels and show that in this context Myc's oncogenic potential is suppressed. Our findings demonstrate that the ability of Myc to increase protein synthesis directly augments cell size and is sufficient to accelerate cell cycle progression independently of known cell cycle targets transcriptionally regulated by Myc. In addition, when protein synthesis is restored to normal levels, Myc overexpressing precancerous cells are more efficiently eliminated by programmed cell death. Our findings reveal a novel paradigm that links increases in general protein synthesis rates downstream of an oncogenic signal to a specific molecular impairment in the modality of translation initiation employed to regulate the expression of selective mRNAs. We show that an aberrant increase in cap-dependent translation downstream Myc hyperactivation specifically impairs the translational switch to internal ribosomal entry site (IRES)-dependent translation required for accurate mitotic progression. Failure of this translational switch results in reduced mitotic-specific expression of the endogenous IRES-dependent form of Cdk11 (p58-PITSLRE)3-5, which leads to cytokinesis defects and is associated with increased centrosome numbers and genome instability in Eμ–Myc/+ mice. When accurate translational control is re-established in Eμ–Myc/+ mice, genome instability is suppressed. Our findings reveal how perturbations in translational control provide a highly specific outcome on gene expression, genome stability, and

SIRT1 Limits Adipocyte Hyperplasia through c-Myc Inhibition*

PubMed Central

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

2016-01-01

The expansion of fat mass in the obese state is due to increased adipocyte hypertrophy and hyperplasia. The molecular mechanism that drives adipocyte hyperplasia remains unknown. The NAD+-dependent protein deacetylase sirtuin 1 (SIRT1), a key regulator of mammalian metabolism, maintains proper metabolic functions in many tissues, counteracting obesity. Here we report that differentiated adipocytes are hyperplastic when SIRT1 is knocked down stably in mouse 3T3-L1 preadipocytes. This phenotype is associated with dysregulated adipocyte metabolism and enhanced inflammation. We also demonstrate that SIRT1 is a key regulator of proliferation in preadipocytes. Quantitative proteomics reveal that the c-Myc pathway is altered to drive enhanced proliferation in SIRT1-silenced 3T3-L1 cells. Moreover, c-Myc is hyperacetylated, levels of p27 are reduced, and cyclin-dependent kinase 2 (CDK2) is activated upon SIRT1 reduction. Remarkably, differentiating SIRT1-silenced preadipocytes exhibit enhanced mitotic clonal expansion accompanied by reduced levels of p27 as well as elevated levels of CCAAT/enhancer-binding protein β (C/EBPβ) and c-Myc, which is also hyperacetylated. c-Myc activation and enhanced proliferation phenotype are also found to be SIRT1-dependent in proliferating mouse embryonic fibroblasts and differentiating human SW872 preadipocytes. Reducing both SIRT1 and c-Myc expression in 3T3-L1 cells simultaneously does not induce the adipocyte hyperplasia phenotype, confirming that SIRT1 controls adipocyte hyperplasia through c-Myc regulation. A better understanding of the molecular mechanisms of adipocyte hyperplasia will open new avenues toward understanding obesity. PMID:26655722

Bardoxolone Methyl and a Related Triterpenoid Downregulate cMyc Expression in Leukemia Cells

PubMed Central

Jin, Un-Ho; Cheng, Yating; Zhou, Beiyan

2017-01-01

Structurally related pentacyclic triterpenoids methyl 2-cyano-3,12-dioxoolean-1,9-dien-28-oate [bardoxolone-methyl (Bar-Me)] and methyl 2-trifluoromethyl-3,11-dioxoolean-1,12-dien-30-oate (CF3DODA-Me) contain 2-cyano-1-en-3-one and 2-trifluoromethyl-1-en-3-one moieties, respectively, in their A-rings and differ in the position of their en-one structures in ring C. Only Bar-Me forms a Michael addition adduct with glutathione (GSH) and inhibits IKKβ phosphorylation. These differences may be due to steric hindrance by the 11-keto group in CF3DODA-Me, which prevents Michael addition by the conjugated en-one in the A-ring. In contrast, both Bar-Me and CF3DODA-Me induce reactive oxygen species in HL-60 and Jurkat leukemia cells, inhibit cell growth, induce apoptosis and differentiation, and decrease expression of specificity proteins (Sp) 1, 3, and 4, and cMyc, and these effects are significantly attenuated after cotreatment with the antioxidant GSH. In contrast to solid tumor–derived cells, cMyc and Sp transcriptions are regulated independently and cMyc plays a more predominant role than Sp transcription factors in regulating HL-60 or Jurkat cell proliferation and differentiation compared with that observed in cells derived from solid tumors. PMID:28275049

Bardoxolone Methyl and a Related Triterpenoid Downregulate cMyc Expression in Leukemia Cells.

PubMed

Jin, Un-Ho; Cheng, Yating; Zhou, Beiyan; Safe, Stephen

2017-05-01

Structurally related pentacyclic triterpenoids methyl 2-cyano-3,12-dioxoolean-1,9-dien-28-oate [bardoxolone-methyl (Bar-Me)] and methyl 2-trifluoromethyl-3,11-dioxoolean-1,12-dien-30-oate (CF 3 DODA-Me) contain 2-cyano-1-en-3-one and 2-trifluoromethyl-1-en-3-one moieties, respectively, in their A-rings and differ in the position of their en-one structures in ring C. Only Bar-Me forms a Michael addition adduct with glutathione (GSH) and inhibits IKK β phosphorylation. These differences may be due to steric hindrance by the 11-keto group in CF 3 DODA-Me, which prevents Michael addition by the conjugated en-one in the A-ring. In contrast, both Bar-Me and CF 3 DODA-Me induce reactive oxygen species in HL-60 and Jurkat leukemia cells, inhibit cell growth, induce apoptosis and differentiation, and decrease expression of specificity proteins (Sp) 1, 3, and 4, and cMyc, and these effects are significantly attenuated after cotreatment with the antioxidant GSH. In contrast to solid tumor-derived cells, cMyc and Sp transcriptions are regulated independently and cMyc plays a more predominant role than Sp transcription factors in regulating HL-60 or Jurkat cell proliferation and differentiation compared with that observed in cells derived from solid tumors. Copyright © 2017 by The American Society for Pharmacology and Experimental Therapeutics.

Both coding exons of the c-myc gene contribute to its posttranscriptional regulation in the quiescent liver and regenerating liver and after protein synthesis inhibition.

PubMed Central

Lavenu, A; Pistoi, S; Pournin, S; Babinet, C; Morello, D

1995-01-01

In vivo, the steady-state level of c-myc mRNA is mainly controlled by posttranscriptional mechanisms. Using a panel of transgenic mice in which various versions of the human c-myc proto-oncogene were under the control of major histocompatibility complex H-2Kb class I regulatory sequences, we have shown that the 5' and the 3' noncoding sequences are dispensable for obtaining a regulated expression of the transgene in adult quiescent tissues, at the start of liver regeneration, and after inhibition of protein synthesis. These results indicated that the coding sequences were sufficient to ensure a regulated c-myc expression. In the present study, we have pursued this analysis with transgenes containing one or the other of the two c-myc coding exons either alone or in association with the c-myc 3' untranslated region. We demonstrate that each of the exons contains determinants which control c-myc mRNA expression. Moreover, we show that in the liver, c-myc exon 2 sequences are able to down-regulate an otherwise stable H-2K mRNA when embedded within it and to induce its transient accumulation after cycloheximide treatment and soon after liver ablation. Finally, the use of transgenes with different coding capacities has allowed us to postulate that the primary mRNA sequence itself and not c-Myc peptides is an important component of c-myc posttranscriptional regulation. PMID:7623834

c-Myc-Dependent Cell Competition in Human Cancer Cells.

PubMed

Patel, Manish S; Shah, Heta S; Shrivastava, Neeta

2017-07-01

Cell Competition is an interaction between cells for existence in heterogeneous cell populations of multicellular organisms. This phenomenon is involved in initiation and progression of cancer where heterogeneous cell populations compete directly or indirectly for the survival of the fittest based on differential gene expression. In Drosophila, cells having lower dMyc expression are eliminated by cell competition through apoptosis when present in the milieu of cells having higher dMyc expression. Thus, we designed a study to develop c-Myc (human homolog) dependent in vitro cell competition model of human cancer cells. Cells with higher c-Myc were transfected with c-myc shRNA to prepare cells with lower c-Myc and then co-cultured with the same type of cells having a higher c-Myc in equal ratio. Cells with lower c-Myc showed a significant decrease in numbers when compared with higher c-Myc cells, suggesting "loser" and "winner" status of cells, respectively. During microscopy, engulfment of loser cells by winner cells was observed with higher expression of JNK in loser cells. Furthermore, elimination of loser cells was prevented significantly, when co-cultured cells were treated with the JNK (apoptosis) inhibitor. Above results indicate elimination of loser cells in the presence of winner cells by c-Myc-dependent mechanisms of cell competition in human cancer cells. This could be an important mechanism in human tumors where normal cells are eliminated by c-Myc-overexpressed tumor cells. J. Cell. Biochem. 118: 1782-1791, 2017. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

Myc and Omomyc functionally associate with the Protein Arginine Methyltransferase 5 (PRMT5) in glioblastoma cells

PubMed Central

Mongiardi, Maria Patrizia; Savino, Mauro; Bartoli, Laura; Beji, Sara; Nanni, Simona; Scagnoli, Fiorella; Falchetti, Maria Laura; Favia, Annarita; Farsetti, Antonella; Levi, Andrea; Nasi, Sergio; Illi, Barbara

2015-01-01

The c-Myc protein is dysregulated in many human cancers and its function has not been fully elucitated yet. The c-Myc inhibitor Omomyc displays potent anticancer properties in animal models. It perturbs the c-Myc protein network, impairs c-Myc binding to the E-boxes, retaining transrepressive properties and inducing histone deacetylation. Here we have employed Omomyc to further analyse c-Myc activity at the epigenetic level. We show that both Myc and Omomyc stimulate histone H4 symmetric dimethylation of arginine (R) 3 (H4R3me2s), in human glioblastoma and HEK293T cells. Consistently, both associated with protein Arginine Methyltransferase 5 (PRMT5)—the catalyst of the reaction—and its co-factor Methylosome Protein 50 (MEP50). Confocal experiments showed that Omomyc co-localized with c-Myc, PRMT5 and H4R3me2s-enriched chromatin domains. Finally, interfering with PRMT5 activity impaired target gene activation by Myc whereas it restrained Omomyc-dependent repression. The identification of a histone-modifying complex associated with Omomyc represents the first demonstration of an active role of this miniprotein in modifying chromatin structure and adds new information regarding its action on c-Myc targets. More importantly, the observation that c-Myc may recruit PRMT5-MEP50, inducing H4R3 symmetric di-methylation, suggests previously unpredictable roles for c-Myc in gene expression regulation and new potential targets for therapy. PMID:26563484

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

Amino acid-dependent cMyc expression is essential for NK cell metabolic and functional responses in mice.

PubMed

Loftus, Róisín M; Assmann, Nadine; Kedia-Mehta, Nidhi; O'Brien, Katie L; Garcia, Arianne; Gillespie, Conor; Hukelmann, Jens L; Oefner, Peter J; Lamond, Angus I; Gardiner, Clair M; Dettmer, Katja; Cantrell, Doreen A; Sinclair, Linda V; Finlay, David K

2018-06-14

Natural killer (NK) cells are lymphocytes with important anti-tumour functions. Cytokine activation of NK cell glycolysis and oxidative phosphorylation (OXPHOS) are essential for robust NK cell responses. However, the mechanisms leading to this metabolic phenotype are unclear. Here we show that the transcription factor cMyc is essential for IL-2/IL-12-induced metabolic and functional responses in mice. cMyc protein levels are acutely regulated by amino acids; cMyc protein is lost rapidly when glutamine is withdrawn or when system L-amino acid transport is blocked. We identify SLC7A5 as the predominant system L-amino acid transporter in activated NK cells. Unlike other lymphocyte subsets, glutaminolysis and the tricarboxylic acid cycle do not sustain OXPHOS in activated NK cells. Glutamine withdrawal, but not the inhibition of glutaminolysis, results in the loss of cMyc protein, reduced cell growth and impaired NK cell responses. These data identify an essential role for amino acid-controlled cMyc for NK cell metabolism and function.

Targeted repression of AXIN2 and MYC gene expression using designer TALEs

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rennoll, Sherri A.; Scott, Samantha A.; Yochum, Gregory S., E-mail: gsy3@psu.edu

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 adjacentmore » 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.« less

Clinicopathological significance of c-MYC in esophageal squamous cell carcinoma.

PubMed

Lian, Yu; Niu, Xiangdong; Cai, Hui; Yang, Xiaojun; Ma, Haizhong; Ma, Shixun; Zhang, Yupeng; Chen, Yifeng

2017-07-01

Esophageal squamous cell carcinoma is one of the most common malignant tumors. The oncogene c-MYC is thought to be important in the initiation, promotion, and therapy resistance of cancer. In this study, we aim to investigate the clinicopathologic roles of c-MYC in esophageal squamous cell carcinoma tissue. This study is aimed at discovering and analyzing c-MYC expression in a series of human esophageal tissues. A total of 95 esophageal squamous cell carcinoma samples were analyzed by the western blotting and immunohistochemistry techniques. Then, correlation of c-MYC expression with clinicopathological features of esophageal squamous cell carcinoma patients was statistically analyzed. In most esophageal squamous cell carcinoma cases, the c-MYC expression was positive in tumor tissues. The positive rate of c-MYC expression in tumor tissues was 61.05%, obviously higher than the adjacent normal tissues (8.42%, 8/92) and atypical hyperplasia tissues (19.75%, 16/95). There was a statistical difference among adjacent normal tissues, atypical hyperplasia tissues, and tumor tissues. Overexpression of the c-MYC was detected in 61.05% (58/95) esophageal squamous cell carcinomas, which was significantly correlated with the degree of differentiation (p = 0.004). The positive rate of c-MYC expression was 40.0% in well-differentiated esophageal tissues, with a significantly statistical difference (p = 0.004). The positive rate of c-MYC was 41.5% in T1 + T2 esophageal tissues and 74.1% in T3 + T4 esophageal tissues, with a significantly statistical difference (p = 0.001). The positive rate of c-MYC was 45.0% in I + II esophageal tissues and 72.2% in III + IV esophageal tissues, with a significantly statistical difference (p = 0.011). The c-MYC expression strongly correlated with clinical staging (p = 0.011), differentiation degree (p = 0.004), lymph node metastasis (p = 0.003), and invasion depth (p = 0.001) of patients with esophageal squamous cell carcinoma. The c-MYC was

A c-Myc and surface CD19 signaling amplification loop promotes B cell lymphoma development and progression in mice.

PubMed

Poe, Jonathan C; Minard-Colin, Veronique; Kountikov, Evgueni I; Haas, Karen M; Tedder, Thomas F

2012-09-01

Malignant B cells responding to external stimuli are likely to gain a growth advantage in vivo. These cells may therefore maintain surface CD19 expression to amplify transmembrane signals and promote their expansion and survival. To determine whether CD19 expression influences this process, Eμ-Myc transgenic (c-Myc(Tg)) mice that develop aggressive and lethal B cell lymphomas were made CD19 deficient (c-Myc(Tg)CD19⁻/⁻). Compared with c-Myc(Tg) and c-Myc(Tg)CD19⁺/⁻ littermates, the median life span of c-Myc(Tg)CD19⁻/⁻ mice was prolonged by 81-83% (p < 0.0001). c-Myc(Tg)CD19⁻/⁻ mice also lived 42% longer than c-Myc(Tg) littermates following lymphoma detection (p < 0.01). Tumor cells in c-Myc(Tg) and c-Myc(Tg)CD19⁻/⁻ mice were B lineage derived, had a similar phenotype with a large blastlike appearance, invaded multiple lymphoid tissues, and were lethal when adoptively transferred into normal recipient mice. Importantly, reduced lymphomagenesis in c-Myc(Tg)CD19⁻/⁻ mice was not due to reductions in early B cell numbers prior to disease onset. In mechanistic studies, constitutive c-Myc expression enhanced CD19 expression and phosphorylation on active sites. Reciprocally, CD19 expression in c-Myc(Tg) B cells enhanced c-Myc phosphorylation at regulatory sites, sustained higher c-Myc protein levels, and maintained a balance of cyclin D2 expression over that of cyclin D3. These findings define a new and novel c-Myc:CD19 regulatory loop that positively influences B cell transformation and lymphoma progression.

Suppression of c-Myc induces apoptosis via an AMPK/mTOR-dependent pathway by 4-O-methyl-ascochlorin in leukemia cells.

PubMed

Shin, Jae-Moon; Jeong, Yun-Jeong; Cho, Hyun-Ji; Magae, Junji; Bae, Young-Seuk; Chang, Young-Chae

2016-05-01

4-O-Methyl-ascochlorin (MAC) is a methylated derivative of the prenyl-phenol antibiotic ascochlorin, which was isolated from an incomplete fungus, Ascochyta viciae. Although the effects of MAC on apoptosis have been reported, the underlying mechanisms remain unknown. Here, we show that MAC promoted apoptotic cell death and downregulated c-Myc expression in K562 human leukemia cells. The effect of MAC on apoptosis was similar to that of 10058-F4 (a c-Myc inhibitor) or c-Myc siRNA, suggesting that the downregulation of c-Myc expression plays a role in the apoptotic effect of MAC. Further investigation showed that MAC downregulated c-Myc by inhibiting protein synthesis. MAC promoted the phosphorylation of AMP-activated protein kinase (AMPK) and inhibited the phosphorylation of mammalian target of rapamycin (mTOR) and its target proteins, including p70S6 K and 4E-BP-1. Treatment of cells with AICAR (an AMPK activator), rapamycin (an mTOR inhibitor), or mTOR siRNA downregulated c-Myc expression and induced apoptosis to a similar extent to that of MAC. These results suggest that the effect of MAC on apoptosis induction in human leukemia cells is mediated by the suppression of c-Myc protein synthesis via an AMPK/mTOR-dependent mechanism.

Disruption of MEK/ERK/c-Myc signaling radiosensitizes prostate cancer cells in vitro and in vivo.

PubMed

Ciccarelli, Carmela; Di Rocco, Agnese; Gravina, Giovanni Luca; Mauro, Annunziata; Festuccia, Claudio; Del Fattore, Andrea; Berardinelli, Paolo; De Felice, Francesca; Musio, Daniela; Bouché, Marina; Tombolini, Vincenzo; Zani, Bianca Maria; Marampon, Francesco

2018-06-29

Prostate cancer (PCa) cell radioresistance causes the failure of radiation therapy (RT) in localized or locally advanced disease. The aberrant accumulation of c-Myc oncoprotein, known to promote PCa onset and progression, may be due to the control of gene transcription and/or MEK/ERK-regulated protein stabilization. Here, we investigated the role of MEK/ERK signaling in PCa. LnCAP, 22Rv1, DU145, and PC3 PCa cell lines were used in in vitro and in vivo experiments. U0126, trametinib MEK/ERK inhibitors, and c-Myc shRNAs were used. Radiation was delivered using an x-6 MV photon linear accelerator. U0126 in vivo activity alone or in combination with irradiation was determined in murine xenografts. Inhibition of MEK/ERK signaling down-regulated c-Myc protein in PCa cell lines to varying extents by affecting expression of RNA and protein, which in turn determined radiosensitization in in vitro and in vivo xenograft models of PCa cells. The crucial role played by c-Myc in the MEK/ERK pathways was demonstrated in 22Rv1 cells by the silencing of c-Myc by means of short hairpin mRNA, which yielded effects resembling the targeting of MEK/ERK signaling. The clinically approved compound trametinib used in vitro yielded the same effects as U0126 on growth and C-Myc expression. Notably, U0126 and trametinib induced a drastic down-regulation of BMX, which is known to prevent apoptosis in cancer cells. The results of our study suggest that signal transduction-based therapy can, by disrupting the MEK/ERK/c-Myc axis, reduce human PCa radioresistance caused by increased c-Myc expression in vivo and in vitro and restores apoptosis signals.

Hepatitis C virus core protein targets 4E-BP1 expression and phosphorylation and potentiates Myc-induced liver carcinogenesis in transgenic mice.

PubMed

Abdallah, Cosette; Lejamtel, Charlène; Benzoubir, Nassima; Battaglia, Serena; Sidahmed-Adrar, Nazha; Desterke, Christophe; Lemasson, Matthieu; Rosenberg, Arielle R; Samuel, Didier; Bréchot, Christian; Pflieger, Delphine; Le Naour, François; Bourgeade, Marie-Françoise

2017-08-22

Hepatitis C virus (HCV) is a leading cause of liver diseases including the development of hepatocellular carcinoma (HCC). Particularly, core protein has been involved in HCV-related liver pathologies. However, the impact of HCV core on signaling pathways supporting the genesis of HCC remains largely elusive. To decipher the host cell signaling pathways involved in the oncogenic potential of HCV core, a global quantitative phosphoproteomic approach was carried out. This study shed light on novel differentially phosphorylated proteins, in particular several components involved in translation. Among the eukaryotic initiation factors that govern the translational machinery, 4E-BP1 represents a master regulator of protein synthesis that is associated with the development and progression of cancers due to its ability to increase protein expression of oncogenic pathways. Enhanced levels of 4E-BP1 in non-modified and phosphorylated forms were validated in human hepatoma cells and in mouse primary hepatocytes expressing HCV core, in the livers of HCV core transgenic mice as well as in HCV-infected human primary hepatocytes. The contribution of HCV core in carcinogenesis and the status of 4E-BP1 expression and phosphorylation were studied in HCV core/Myc double transgenic mice. HCV core increased the levels of 4E-BP1 expression and phosphorylation and significantly accelerated the onset of Myc-induced tumorigenesis in these double transgenic mice. These results reveal a novel function of HCV core in liver carcinogenesis potentiation. They position 4E-BP1 as a tumor-specific target of HCV core and support the involvement of the 4E-BP1/eIF4E axis in hepatocarcinogenesis.

KCTD2, an adaptor of Cullin3 E3 ubiquitin ligase, suppresses gliomagenesis by destabilizing c-Myc

PubMed Central

Kim, Eun-Jung; Kim, Sung-Hak; Jin, Xiong; Jin, Xun; Kim, Hyunggee

2017-01-01

Cullin3 E3 ubiquitin ligase ubiquitinates a wide range of substrates through substrate-specific adaptors Bric-a-brac, Tramtrack, and Broad complex (BTB) domain proteins. These E3 ubiquitin ligase complexes are involved in diverse cellular functions. Our recent study demonstrated that decreased Cullin3 expression induces glioma initiation and correlates with poor prognosis of patients with malignant glioma. However, the substrate recognition mechanism associated with tumorigenesis is not completely understood. Through yeast two-hybrid screening, we identified potassium channel tetramerization domain-containing 2 (KCTD2) as a BTB domain protein that binds to Cullin3. The interaction of Cullin3 and KCTD2 was verified using immunoprecipitation and immunofluorescence. Of interest, KCTD2 expression was markedly decreased in patient-derived glioma stem cells (GSCs) compared with non-stem glioma cells. Depletion of KCTD2 using a KCTD2-specific short-hairpin RNA in U87MG glioma cells and primary Ink4a/Arf-deficient murine astrocytes markedly increased self-renewal activity in addition with an increased expression of stem cell markers, and mouse in vivo intracranial tumor growth. As an underlying mechanism for these KCTD2-mediated phenotypic changes, we demonstrated that KCTD2 interacts with c-Myc, which is a key stem cell factor, and causes c-Myc protein degradation by ubiquitination. As a result, KCTD2 depletion acquires GSC features and affects aerobic glycolysis via expression changes in glycolysis-associated genes through c-Myc protein regulation. Of clinical significance was our finding that patients having a profile of KCTD2 mRNA-low and c-Myc gene signature-high, but not KCTD2 mRNA-low and c-Myc mRNA-high, are strongly associated with poor prognosis. This study describes a novel regulatory mode of c-Myc protein in malignant gliomas and provides a potential framework for glioma therapy by targeting c-Myc function. PMID:28060381

c-myc overexpression causes anaplasia in medulloblastoma.

PubMed

Stearns, Duncan; Chaudhry, Aneeka; Abel, Ty W; Burger, Peter C; Dang, Chi V; Eberhart, Charles G

2006-01-15

Both anaplasia and increased c-myc gene expression have been shown to be negative prognostic indicators for survival in medulloblastoma patients. myc gene amplification has been identified in many large cell/anaplastic medulloblastoma, but no causative link between c-myc and anaplastic changes has been established. To address this, we stably overexpressed c-myc in two medulloblastoma cell lines, DAOY and UW228, and examined the changes in growth characteristics. When analyzed in vitro, cell lines with increased levels of c-myc had higher rates of growth and apoptosis as well as significantly improved ability to form colonies in soft agar compared with control. When injected s.c. into nu/nu mice, flank xenograft tumors with high levels of c-myc in DAOY cell line background were 75% larger than those derived from control. Overexpression of c-myc was required for tumor formation by UW228 cells. Most remarkably, the histopathology of the Myc tumors was severely anaplastic, with large areas of necrosis/apoptosis, increased nuclear size, and macronucleoli. Indices of proliferation and apoptosis were also significantly higher in Myc xenografts. Thus, c-myc seems to play a causal role in inducing anaplasia in medulloblastoma. Because anaplastic changes are often observed in recurrent medulloblastoma, we propose that c-myc dysregulation is involved in the progression of these malignant embryonal neoplasms.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ledee, Dolena; Smith, Lincoln; Bruce, Margaret

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

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

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

PubMed Central

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

2014-01-01

AIM: 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). METHODS: 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. RESULTS: 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

N-Myc Differentially Regulates Expression of MXI1 Isoforms in Neuroblastoma1

PubMed Central

Armstrong, Michael B; Mody, Rajen J; Ellis, D Christian; Hill, Adam B; Erichsen, David A; Wechsler, Daniel S

2013-01-01

Amplification of the MYCN proto-oncogene is associated with a poor prognosis in patients with metastatic neuroblastoma (NB). MYCN encodes the N-Myc protein, a transcriptional regulator that dimerizes with the Max transcription factor, binds to E-box DNA sequences, and regulates genes involved in cell growth and apoptosis. Overexpression of N-Myc leads to transcriptional activation and an increase in NB cell proliferation. Mxi1, a member of the Myc family of transcriptional regulators, also binds to Max. However, Mxi1 is a transcriptional repressor and inhibits proliferation of NB cells, suggesting that Mxi1 functions as an N-Myc antagonist. Our laboratory previously identified Mxi1-0, an alternatively transcribed Mxi1 isoform. Mxi1-0 has properties distinct from those of Mxi1; in contrast to Mxi1, Mxi1-0 is unable to suppress c-Myc-dependent transcription. We now show that Mxi1-0 expression increases in response to MYCN overexpression in NB cells, with a positive correlation between MYCN and MXI1-0 RNA levels. We also show that N-Myc expression differentially regulates the MXI1 and MXI1-0 promoters: Increased MYCN expression suppresses MXI1 promoter activity while enhancing transcription through the MXI1-0 promoter. Finally, induction of Mxi1-0 leads to increased proliferation, whereas expression of Mxi1 inhibits cell growth, indicating differential roles for these two proteins. These data suggest that N-Myc differentially regulates the expression of MXI1 and MXI1-0 and can alter the balance between the two transcription factors. Furthermore, MXI1-0 appears to be a downstream target of MYCN-dependent signaling pathways and may contribute to N-Myc-dependent cell growth and proliferation. PMID:24403858

c-Myc-induced apoptosis in fibroblasts is inhibited by specific cytokines.

PubMed Central

Harrington, E A; Bennett, M R; Fanidi, A; Evan, G I

1994-01-01

We have investigated the mechanism by which deregulated expression of c-Myc induces death by apoptosis in serum-deprived fibroblasts. We demonstrate that Myc-induced apoptosis in low serum is inhibited by a restricted group of cytokines, principally the insulin-like growth factors and PDGF. Cytokine-mediated protection from apoptosis is not linked to the cytokines' abilities to promote growth. Protection from apoptosis is evident in the post-commitment (mitogen-independent) S/G2/M phases of the cell cycle and also in cells that are profoundly blocked in cell cycle progression by drugs. Moreover, IGF-I inhibition of apoptosis occurs in the absence of protein synthesis, and so does not require immediate early gene expression. We conclude that c-Myc-induced apoptosis does not result from a conflict of growth signals but appears to be a normal physiological aspect of c-Myc function whose execution is regulated by the availability of survival factors. We discuss the possible implications of these findings for models of mammalian cell growth in vivo. Images PMID:8045259

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

NASA Technical Reports Server (NTRS)

Chen, C.; Sytkowski, A. J.

2001-01-01

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

Definition of MYC genetic heteroclonality in diffuse large B-cell lymphoma with 8q24 rearrangement and its impact on protein expression.

PubMed

Valera, Alexandra; Epistolio, Samantha; Colomo, Lluis; Riva, Alice; Balagué, Olga; Dlouhy, Ivan; Tzankov, Alexandar; Bühler, Marco; Haralambieva, Eugenia; Campo, Elias; Soldini, Davide; Mazzucchelli, Luca; Martin, Vittoria

2016-08-01

MYC rearrangement can be detected in a subgroup of diffuse large B-cell lymphoma characterized by unfavorable prognosis. In contrast to Burkitt lymphoma, the correlation between MYC rearrangement and MYC protein expression in diffuse large B-cell lymphoma is less clear, as approximately one-third of rearranged cases show negative or low expression by immunohistochemistry. To better understand whether specific characteristics of the MYC rearrangement may influence its protein expression, we investigated 43 de novo diffuse large B-cell lymphoma positive for 8q24 rearrangement by FISH, using 14 Burkitt lymphoma for comparison. Different cell populations (clones), breakpoints (classical vs non-classical FISH patterns), partner genes (IGH vs non-IGH) and immunostaining were detected and analyzed using computerized image systems. In a subgroup of diffuse large B-cell lymphoma, we observed different clones within the same tumor distinguishing the founder clone with MYC rearrangement alone from other subclones, carrying MYC rearrangement coupled with loss/extra copies of derivatives/normal alleles. This picture, which we defined MYC genetic heteroclonality, was found in 42% of cases and correlated to negative MYC expression (P=0.026). Non-classical FISH breakpoints were detected in 16% of diffuse large B-cell lymphoma without affecting expression (P=0.040). Non-IGH gene was the preferential partner of rearrangement in those diffuse large B-cell lymphoma showing MYC heteroclonality (P=0.016) and/or non-classical FISH breakpoints (P=0.058). MYC heteroclonality was not observed in Burkitt lymphoma and all cases had positive MYC expression. Non-classical FISH MYC breakpoint and non-IGH partner were found in 29 and 20% of Burkitt lymphoma, respectively. In conclusion, MYC genetic heteroclonality is a frequent event in diffuse large B-cell lymphoma and may have a relevant role in modulating MYC expression.

cdc25 cell cycle-activating phosphatases and c-myc expression in human non-Hodgkin's lymphomas.

PubMed

Hernández, S; Hernández, L; Beà, S; Cazorla, M; Fernández, P L; Nadal, A; Muntané, J; Mallofré, C; Montserrat, E; Cardesa, A; Campo, E

1998-04-15

cdc25A, cdc25B, and cdc25C are a family of human phosphatases that activate the cyclin-dependent kinases at different points of the cell cycle. cdc25A and cdc25B have been shown to have oncogenic potential, and they have been identified as transcriptional targets of c-myc. To determine the role of cdc25 genes in the pathogenesis of human lymphomas and their possible correlation with c-myc deregulation, we have analyzed the expression of cdc25A, cdc25B, and cdc25C and c-myc genes in a series of 63 non-Hodgkin's lymphomas and 8 nonneoplastic lymphoid tissues. The mRNA levels of the three phosphatases in the nonneoplastic tissues were negative or negligible. cdc25B overexpression was detected in 35 tumors (56%). This overexpression was more frequently found in aggressive (81%) than in indolent lymphomas (36%; P < 0.01). cdc25B overexpression was also significantly associated with a higher proliferative activity of the tumors. No cdc25B gene amplification or rearrangements were detected by Southern blot analysis. A biallelic EcoRI polymorphism of cdc25B gene was identified with a similar distribution in patients with lymphoma and in a normal population. cdc25A was overexpressed in three aggressive lymphomas. No detectable cdc25C mRNA levels were seen in any of the tumors. c-myc was overexpressed in 43% of tumors, and it correlated significantly with the presence of cdc25B up-regulation. Twenty-six of 35 (74%) lymphomas with high levels of cdc25B mRNA also showed c-myc overexpression, whereas 27 of 28 (96%) tumors without detectable or with very low cdc25B expression also had undetectable c-myc levels (P < 0.0001). In addition, a significant linear correlation was found between the cdc25B and c-myc mRNA levels (r = 0.575, P < 0.001). These findings suggest that cdc25B overexpression in non-Hodkin's lymphoma may participate in the pathogenesis of aggressive variants, and it may cooperate with c-myc oncogene in the development of these tumors.

[Survival of patients with primary central nervous system diffuse large B-cell lymphoma: impact of gene aberrations and protein overexpression of bcl-2 and C-MYC, and selection of chemotherapy regimens].

PubMed

Yin, W J; Zhu, X; Yang, H Y; Sun, W Y; Wu, M J

2018-01-08

Objective: To investigate the impact of clinicopathological features, gene rearrangements and protein expression of bcl-6, bcl-2, C-MYC and chemotherapy regime on the prognosis of patients with primary central nervous system diffuse large B-cell lymphoma (PCNS-DLBCL). Methods: Thirty-three cases of PCNS-DLBCL diagnosed from January 2006 to December 2016 at Zhejiang Cancer Hospital were collected. The expression of CD10, bcl-6, bcl-2, MUM1 and MYC were detected by immunohistochemical staining (IHC). The presence of EB virus was detected by in situ hybridization(EBER). Copy number variation (ICN) and translocation status of bcl-6, bcl-2 and C-MYC genes were detected by fluorescence in situ hybridization (FISH). The relationship between the above indexes and the prognosis was analyzed by univariate, bivariate survival analysis and multiple Cox hazard regression analysis. Results: The study included 33 patients of PCNS-DLBCL, without evidence of primary or secondary immunodeficient disease. Male to female ratio was 1.36∶1.00, and the average age was 56 years. Twenty cases had single lesion while 13 had multiple lesions. Deep brain involvement was seen in 12 cases. All patients underwent partial or total tumor resection. Five patients received whole brain post-surgery radiotherapy, nine patients received high-dose methotrexate (HD-MTX) based chemotherapy, and 12 patients received whole-brain radiotherapy combined with HD-MTX based chemotherapy. Severn patients received no further treatment and rituximab was used in 8 patients. According to the Hans model, 27 cases were classified as non-GCB subtypes (81.8%). Bcl-2 was positive in 25 cases (75.8%, 25/33) and highly expressed in 8 (24.2%). MYC was positive in 12 cases (36.4%) and double expression of bcl-2 and MYC was seen in 6 cases. EBER positive rate was 10.0%(3/30), all of which had multiple lesions. Two bcl-6 gene translocations and 3 amplifications were found in 28 patients. Two translocations, 3 ICN or with both

c-Myc-Induced Survivin Is Essential for Promoting the Notch-Dependent T Cell Differentiation from Hematopoietic Stem Cells

PubMed Central

Haque, Rizwanul; Song, Jianyong; Haque, Mohammad; Lei, Fengyang; Sandhu, Praneet; Ni, Bing; Zheng, Songguo; Fang, Deyu; Yang, Jin-Ming; Song, Jianxun

2017-01-01

Notch is indispensable for T cell lineage commitment, and is needed for thymocyte differentiation at early phases. During early stages of T cell development, active Notch prevents other lineage potentials including B cell lineage and myeloid cell (e.g., dendritic cell) lineage. Nevertheless, the precise intracellular signaling pathways by which Notch promotes T cell differentiation remain unclear. Here we report that the transcription factor c-Myc is a key mediator of the Notch signaling–regulated T cell differentiation. In a well-established in vitro differentiation model of T lymphocytes from hematopoietic stem cells, we showed that Notch1 and 4 directly promoted c-Myc expression; dominant-negative (DN) c-Myc inhibited early T cell differentiation. Moreover, the c-Myc expression activated by Notch signaling increased the expression of survivin, an inhibitor of apoptosis (IAP) protein. We further demonstrated that over-expression of c-Myc increased the abundance of survivin and the T cell differentiation thereof, whereas dn c-Myc reduced survivin levels and concomitantly retarded the differentiation. The c-Myc–dependent survivin induction is functionally germane, because Notch-dependent T cell differentiation was canceled by the depletion of survivin. These results identify both c-Myc and survivin as important mediators of the Notch signaling–regulated differentiation of T lymphocytes from hematopoietic stem cells. PMID:28272325

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.

Gamabufotalin triggers c-Myc degradation via induction of WWP2 in multiple myeloma cells.

PubMed

Yu, Zhenlong; Li, Tao; Wang, Chao; Deng, Sa; Zhang, Baojing; Huo, Xiaokui; Zhang, Bo; Wang, Xiaobo; Zhong, Yuping; Ma, Xiaochi

2016-03-29

Deciding appropriate therapy for multiple myeloma (MM) is challenging because of the occurrence of multiple chromosomal changes and the fatal nature of the disease. In the current study, gamabufotalin (GBT) was isolated from toad venom, and its tumor-specific cytotoxicity was investigated in human MM cells. We found GBT inhibited cell growth and induced apoptosis with the IC50 values <50 nM. Mechanistic studies using functional approaches identified GBT as an inhibitor of c-Myc. Further analysis showed that GBT especially evoked the ubiquitination and degradation of c-Myc protein, thereby globally repressing the expression of c-Myc target genes. GBT treatment inhibited ERK and AKT signals, while stimulating the activation of JNK cascade. An E3 ubiquitin-protein ligase, WWP2, was upregulated following JNK activation and played an important role in c-Myc ubiquitination and degradation through direct protein-protein interaction. The antitumor effect of GBT was validated in a xenograft mouse model and the suppression of MM-induced osteolysis was verified in a SCID-hu model in vivo. Taken together, our study identified the potential of GBT as a promising therapeutic agent in the treatment of MM.

c-Myc Represses Transcription of Epstein-Barr Virus Latent Membrane Protein 1 Early after Primary B Cell Infection.

PubMed

Price, Alexander M; Messinger, Joshua E; Luftig, Micah A

2018-01-15

Recent evidence has shown that the Epstein-Barr virus (EBV) oncogene LMP1 is not expressed at high levels early after EBV infection of primary B cells, despite its being essential for the long-term outgrowth of immortalized lymphoblastoid cell lines (LCLs). In this study, we found that expression of LMP1 increased 50-fold between 7 days postinfection and the LCL state. Metabolic labeling of nascent transcribed mRNA indicated that this was primarily a transcription-mediated event. EBNA2, the key viral transcription factor regulating LMP1, and CTCF, an important chromatin insulator, were recruited to the LMP1 locus similarly early and late after infection. However, the activating histone H3K9Ac mark was enriched at the LMP1 promoter in LCLs relative to that in infected B cells early after infection. We found that high c-Myc activity in EBV-infected lymphoma cells as well as overexpression of c-Myc in an LCL model system repressed LMP1 transcription. Finally, we found that chemical inhibition of c-Myc both in LCLs and early after primary B cell infection increased LMP1 expression. These data support a model in which high levels of endogenous c-Myc activity induced early after primary B cell infection directly repress LMP1 transcription. IMPORTANCE EBV is a highly successful pathogen that latently infects more than 90% of adults worldwide and is also causally associated with a number of B cell malignancies. During the latent life cycle, EBV expresses a set of viral oncoproteins and noncoding RNAs with the potential to promote cancer. Critical among these is the viral latent membrane protein LMP1. Prior work suggests that LMP1 is essential for EBV to immortalize B cells, but our recent work indicates that LMP1 is not produced at high levels during the first few weeks after infection. Here we show that transcription of the LMP1 gene can be negatively regulated by a host transcription factor, c-Myc. Ultimately, understanding the regulation of EBV oncogenes will allow us

Transforming Growth Factor-β1 activates ΔNp63/c-Myc to promote Oral Squamous cell carcinoma

PubMed Central

Hu, Lihua; Li, Zhi; Liu, Jingpeng; Wang, Chunling; Nawshad, Ali

2016-01-01

Objective During the development of oral squamous cell carcinoma (OSCC), the transformed epithelial cells undergo increased proliferation resulting in tumor growth and invasion. Interestingly, throughout all phases of differentiation and progression of OSCC, TGFβ1 induces cell cycle arrest/apoptosis, however; the role of TGFβ1 in promoting cancer cell proliferation has not been explored in detail. The purpose of this study was to identify the effect of TGFβ1 on OSCC cell proliferation. Methods Using both human OSCC samples and cell lines (UMSCC38 and UMSCC 11B), we employed biochemical experiments to show protein, mRNA, gene expression and protein-DNA interactions during OSCC progression. Results Our results showed that TGFβ1 increased OSCC cell proliferation by up-regulating the expression of ΔNp63 and c-Myc oncogenes. While the basal OSCC cell proliferation is sustained by activating ΔNp63, increased induction of c-Myc causes unregulated OSCC cell proliferation. Following induction of the cell cycle by ΔNp63 and c-Myc, cancer cells that halt c-Myc activity undergo EMT/invasion while those that continue to express ΔNp63/c-Myc undergo unlimited progression through the cell cycle. Conclusion We conclude that OSCC proliferation is manifested by the induction of c-Myc in response to TGFβ1 signaling, which is essential for OSCC growth. Our data highlights the potential role of TGFβ1 in the induction of cancer progression and invasion of OSCC. PMID:27567435

Distinct transcriptional MYCN/c-MYC activities are associated with spontaneous regression or malignant progression in neuroblastomas

PubMed Central

Westermann, Frank; Muth, Daniel; Benner, Axel; Bauer, Tobias; Henrich, Kai-Oliver; Oberthuer, André; Brors, Benedikt; Beissbarth, Tim; Vandesompele, Jo; Pattyn, Filip; Hero, Barbara; König, Rainer; Fischer, Matthias; Schwab, Manfred

2008-01-01

Background Amplified MYCN oncogene resulting in deregulated MYCN transcriptional activity is observed in 20% of neuroblastomas and identifies a highly aggressive subtype. In MYCN single-copy neuroblastomas, elevated MYCN mRNA and protein levels are paradoxically associated with a more favorable clinical phenotype, including disseminated tumors that subsequently regress spontaneously (stage 4s-non-amplified). In this study, we asked whether distinct transcriptional MYCN or c-MYC activities are associated with specific neuroblastoma phenotypes. Results We defined a core set of direct MYCN/c-MYC target genes by applying gene expression profiling and chromatin immunoprecipitation (ChIP, ChIP-chip) in neuroblastoma cells that allow conditional regulation of MYCN and c-MYC. Their transcript levels were analyzed in 251 primary neuroblastomas. Compared to localized-non-amplified neuroblastomas, MYCN/c-MYC target gene expression gradually increases from stage 4s-non-amplified through stage 4-non-amplified to MYCN amplified tumors. This was associated with MYCN activation in stage 4s-non-amplified and predominantly c-MYC activation in stage 4-non-amplified tumors. A defined set of MYCN/c-MYC target genes was induced in stage 4-non-amplified but not in stage 4s-non-amplified neuroblastomas. In line with this, high expression of a subset of MYCN/c-MYC target genes identifies a patient subtype with poor overall survival independent of the established risk markers amplified MYCN, disease stage, and age at diagnosis. Conclusions High MYCN/c-MYC target gene expression is a hallmark of malignant neuroblastoma progression, which is predominantly driven by c-MYC in stage 4-non-amplified tumors. In contrast, moderate MYCN function gain in stage 4s-non-amplified tumors induces only a restricted set of target genes that is still compatible with spontaneous regression. PMID:18851746

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

Tripeptidyl Peptidase II Is Required for c-MYC-Induced Centriole Overduplication and a Novel Therapeutic Target in c-MYC-Associated Neoplasms.

PubMed

Duensing, Stefan; Darr, Sebastian; Cuevas, Rolando; Melquiot, Nadja; Brickner, Anthony G; Duensing, Anette; Münger, Karl

2010-09-01

Centrosome aberrations are frequently detected in c-MYC-associated human malignancies. Here, we show that c-MYC-induced centrosome and centriole overduplication critically depend on the protease tripeptidyl peptidase II (TPPII). We found that TPPII localizes to centrosomes and that overexpression of TPPII, similar to c-MYC, can disrupt centriole duplication control and cause centriole multiplication, a process during which maternal centrioles nucleate the formation of more than a single daughter centriole. We report that inactivation of TPPII using chemical inhibitors or siRNA-mediated protein knockdown effectively reduced c-MYC-induced centriole overduplication. Remarkably, the potent and selective TPPII inhibitor butabindide not only potently suppressed centriole aberrations but also caused significant cell death and growth suppression in aggressive human Burkitt lymphoma cells with c-MYC overexpression. Taken together, these results highlight the role of TPPII in c-MYC-induced centriole overduplication and encourage further studies to explore TPPII as a novel antineoplastic drug target.

The role of Myc-induced protein synthesis in cancer

PubMed Central

Ruggero, Davide

2009-01-01

Deregulation in different steps of translational control is an emerging mechanism for cancer formation. One example of an oncogene with a direct role in control of translation is the Myc transcription factor. Myc directly increases protein synthesis rates by controlling the expression of multiple components of the protein synthetic machinery, including ribosomal proteins, initiation factors of translation, Pol III and rDNA. However, the contribution of Myc-dependent increases in protein synthesis towards the multi-step process leading to cancer has remained unknown. Recent evidence strongly suggests that Myc oncogenic signaling may monopolize the translational machinery to elicit cooperative effects on cell growth, cell cycle progression, and genome instability as a mechanism for cancer initiation. Moreover, new genetic tools to restore aberrant increases in protein synthesis control are now available, which should enable the dissection of important mechanisms in cancer that rely on the translational machinery. PMID:19934336

OmoMYC blunts promoter invasion by oncogenic MYC to inhibit gene expression characteristic of MYC-dependent tumors.

PubMed

Jung, L A; Gebhardt, A; Koelmel, W; Ade, C P; Walz, S; Kuper, J; von Eyss, B; Letschert, S; Redel, C; d'Artista, L; Biankin, A; Zender, L; Sauer, M; Wolf, E; Evan, G; Kisker, C; Eilers, M

2017-04-06

MYC genes have both essential roles during normal development and exert oncogenic functions during tumorigenesis. Expression of a dominant-negative allele of MYC, termed OmoMYC, can induce rapid tumor regression in mouse models with little toxicity for normal tissues. How OmoMYC discriminates between physiological and oncogenic functions of MYC is unclear. We have solved the crystal structure of OmoMYC and show that it forms a stable homodimer and as such recognizes DNA in the same manner as the MYC/MAX heterodimer. OmoMYC attenuates both MYC-dependent activation and repression by competing with MYC/MAX for binding to chromatin, effectively lowering MYC/MAX occupancy at its cognate binding sites. OmoMYC causes the largest decreases in promoter occupancy and changes in expression on genes that are invaded by oncogenic MYC levels. A signature of OmoMYC-regulated genes defines subgroups with high MYC levels in multiple tumor entities and identifies novel targets for the eradication of MYC-driven tumors.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hong, Kyung-Soo; Research Center for Ischemic Tissue regeneration, Pusan National University School of Medicine, Yangsan; Park, Jun-Ik

2012-03-01

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

Gene expression profiles in primary pancreatic tumors and metastatic lesions of Ela-c-myc transgenic mice.

PubMed

Thakur, Archana; Bollig, Aliccia; Wu, Jiusheng; Liao, Dezhong J

2008-01-24

Pancreatic carcinoma usually is a fatal disease with no cure, mainly due to its invasion and metastasis prior to diagnosis. We analyzed the gene expression profiles of paired primary pancreatic tumors and metastatic lesions from Ela-c-myc transgenic mice in order to identify genes that may be involved in the pancreatic cancer progression. Differentially expressed selected genes were verified by semi-quantitative and quantitative RT-PCR. To further evaluate the relevance of some of the selected differentially expressed genes, we investigated their expression pattern in human pancreatic cancer cell lines with high and low metastatic potentials. Data indicate that genes involved in posttranscriptional regulation were a major functional category of upregulated genes in both primary pancreatic tumors (PT) and liver metastatic lesions (LM) compared to normal pancreas (NP). In particular, differential expression for splicing factors, RNA binding/pre-mRNA processing factors and spliceosome related genes were observed, indicating that RNA processing and editing related events may play critical roles in pancreatic tumor development and progression. High expression of insulin growth factor binding protein-1 (Igfbp1) and Serine proteinase inhibitor A1 (Serpina1), and low levels or absence of Wt1 gene expression were exclusive to liver metastatic lesion samples. We identified Igfbp1, Serpina1 and Wt1 genes that are likely to be clinically useful biomarkers for prognostic or therapeutic purposes in metastatic pancreatic cancer, particularly in pancreatic cancer where c-Myc is overexpressed.

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

PubMed

Raj, Kritika; Sarkar, Surajit

2017-05-01

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

Cancer-associated fibroblasts promote endometrial cancer growth via activation of interleukin-6/STAT-3/c-Myc pathway.

PubMed

Subramaniam, Kavita S; Omar, Intan Sofia; Kwong, Soke Chee; Mohamed, Zahurin; Woo, Yin Ling; Mat Adenan, Noor Azmi; Chung, Ivy

2016-01-01

Cancer-associated fibroblasts (CAFs) secrete various pro-tumorigenic cytokines, yet the role of these cytokines in the progression of endometrial cancer remains unclear. We found that CAFs isolated from human endometrial cancer (EC) tissues secreted high levels of interleukin-6 (IL-6), which promotes EC cell proliferation in vitro. Neutralizing IL-6 in CAF-conditioned media reduced (47% inhibition) while IL-6 recombinant protein increased cell proliferation (~2.4 fold) of both EC cell lines and primary cultures. IL-6 receptors (IL-6R and gp130) were expressed only in EC epithelial cells but not in CAF, indicating a one-way paracrine signaling. In the presence of CAF-conditioned media, Janus kinase/signal transducers and activators of transcription (JAK/STAT3) pathway was activated in EC cells. Treatment with JAK and STAT3 specific inhibitors, AD412 and STATTIC, respectively, significantly abrogated CAF-mediated cell proliferation, indicating the role of IL-6 activation in EC cell proliferation. We further showed that one of STAT-3 target genes, c-Myc, was highly induced in EC cells after exposure to CAF-conditioned medium at both mRNA (>105-fold vs. control) and protein level (>2-fold vs. control). EC cell proliferation was dependent on c-Myc expression, as RNAi-mediated c-Myc down-regulation led to a significant 46% reduction in cell viability when compared with scrambled control. Interestingly, CAF-conditioned media failed to promote proliferation in EC cells with reduced c-Myc expression, suggesting that CAF-mediated cell proliferation was also dependent on c-Myc expression. Subcutaneous tumor xenograft model showed that EC cells grew at least 1.4 times larger when co-injected with CAF, when compared to those injected with EC cells alone. Mice injected with EC cells with down-regulated c-Myc expression, however, showed at least 2.5 times smaller tumor compared to those in control group. Notably, there was no increase of tumor size when co-injected with CAFs

Primary central nervous system diffuse large B-cell lymphoma shows an activated B-cell-like phenotype with co-expression of C-MYC, BCL-2, and BCL-6.

PubMed

Li, Xiaomei; Huang, Ying; Bi, Chengfeng; Yuan, Ji; He, Hong; Zhang, Hong; Yu, QiuBo; Fu, Kai; Li, Dan

2017-06-01

Diffuse large B-cell lymphoma (DLBCL) is the most common non-Hodgkin lymphoma, whose main prognostic factor is closely related to germinal center B-cell-like subtype (GCB- DLBCL) or activated B-cell-like type (non-GCB-DLBCL). The most common type of primary central nervous system lymphoma is diffuse large B-cell type with poor prognosis and the reason is unclear. This study aims to stratify primary central nervous system diffuse large B-cell lymphoma (PCNS-DLBCL) according to the cell-of-origin (COO) and to investigate the multiple proteins expression of C-MYC, BCL-6, BCL-2, TP53, further to elucidate the reason why primary central nervous system diffuse large B-cell lymphoma possesses a poor clinical outcome as well. Nineteen cases of primary central nervous system DLBCL were stratified according to immunostaining algorithms of Hans, Choi and Meyer (Tally) and we investigated the multiple proteins expression of C-MYC, BCL-6, BCL-2, TP53. The Epstein-Barr virus and Borna disease virus infection were also detected. Among nineteen cases, most (15-17 cases) were assigned to the activated B-cell-like subtype, highly expression of C-MYC (15 cases, 78.9%), BCL-2 (10 cases, 52.6%), BCL-6 (15 cases, 78.9%). Unfortunately, two cases were positive for PD-L1 while PD-L2 was not expressed in any case. Two cases infected with BDV but no one infected with EBV. In conclusion, most primary central nervous system DLBCLs show an activated B-cell-like subtype characteristic and have multiple expressions of C-MYC, BCL-2, BCL-6 protein, these features might be significant factor to predict the outcome and guide treatment of PCNS-DLBCLs. Copyright © 2017 Elsevier GmbH. All rights reserved.

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

PubMed

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

2016-06-02

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

A functional mammalian target of rapamycin complex 1 signaling is indispensable for c-Myc-driven hepatocarcinogenesis.

PubMed

Liu, Pin; Ge, Mengmeng; Hu, Junjie; Li, Xiaolei; Che, Li; Sun, Kun; Cheng, Lili; Huang, Yuedong; Pilo, Maria G; Cigliano, Antonio; Pes, Giovanni M; Pascale, Rosa M; Brozzetti, Stefania; Vidili, Gianpaolo; Porcu, Alberto; Cossu, Antonio; Palmieri, Giuseppe; Sini, Maria C; Ribback, Silvia; Dombrowski, Frank; Tao, Junyan; Calvisi, Diego F; Chen, Ligong; Chen, Xin

2017-07-01

Amplification and/or activation of the c-Myc proto-oncogene is one of the leading genetic events along hepatocarcinogenesis. The oncogenic potential of c-Myc has been proven experimentally by the finding that its overexpression in the mouse liver triggers tumor formation. However, the molecular mechanism whereby c-Myc exerts its oncogenic activity in the liver remains poorly understood. Here, we demonstrate that the mammalian target of rapamycin complex 1 (mTORC1) cascade is activated and necessary for c-Myc-dependent hepatocarcinogenesis. Specifically, we found that ablation of Raptor, the unique member of mTORC1, strongly inhibits c-Myc liver tumor formation. Also, the p70 ribosomal S6 kinase/ribosomal protein S6 and eukaryotic translation initiation factor 4E-binding protein 1/eukaryotic translation initiation factor 4E signaling cascades downstream of mTORC1 are required for c-Myc-driven tumorigenesis. Intriguingly, microarray expression analysis revealed up-regulation of multiple amino acid transporters, including solute carrier family 1 member A5 (SLC1A5) and SLC7A6, leading to robust uptake of amino acids, including glutamine, into c-Myc tumor cells. Subsequent functional studies showed that amino acids are critical for activation of mTORC1 as their inhibition suppressed mTORC1 in c-Myc tumor cells. In human hepatocellular carcinoma specimens, levels of c-Myc directly correlate with those of mTORC1 activation as well as of SLC1A5 and SLC7A6. Our current study indicates that an intact mTORC1 axis is required for c-Myc-driven hepatocarcinogenesis; thus, targeting the mTOR pathway or amino acid transporters may be an effective and novel therapeutic option for the treatment of hepatocellular carcinoma with activated c-Myc signaling. (Hepatology 2017;66:167-181). © 2017 by the American Association for the Study of Liver Diseases.

c-Myc oncogene expression in selected odontogenic cysts and tumors: An immunohistochemical study

PubMed Central

Moosvi, Zama; Rekha, K

2013-01-01

Aim: To investigate the role of c-Myc oncogene in selected odontogenic cysts and tumors. Materials and Methods: Ten cases each of ameloblastoma, adenomatoid odontogenic tumor (AOT), odontogenic keratocyst (OKC), dentigerous cyst, and radicular cyst were selected and primary monoclonal mouse anti-human c-Myc antibody was used in a dilution of 1: 50. Statistical Analysis was performed using Mann Whitney U test. Results: 80% positivity was observed in ameloblastoma, AOT and OKC; 50% positivity in radicular cyst and 20% positivity in dentigerous cyst. Comparison of c-Myc expression between ameloblastoma and AOT did not reveal significant results. Similarly, no statistical significance was observed when results of OKC were compared with ameloblastoma and AOT. In contrast, significant differences were seen on comparison of dentigerous cyst with ameloblastoma and AOT and radicular cyst with AOT. Conclusion: From the above data we conclude that (1) Ameloblastoma and AOT have similar proliferative potential and their biologic behavior cannot possibly be attributed to it. (2) OKC has an intrinsic growth potential which is absent in other cysts and reinforces its classification as keratocystic odontogenic tumor. PMID:23798830

Endoglin inhibits ERK-induced c-Myc and cyclin D1 expression to impede endothelial cell proliferation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pan, Christopher C.; Bloodworth, Jeffrey C.; Mythreye, Karthikeyan

2012-08-03

Highlights: Black-Right-Pointing-Pointer Endoglin inhibits ERK activation in endothelial cells. Black-Right-Pointing-Pointer Endoglin is a regulator of c-Myc and cyclin D1 expression. Black-Right-Pointing-Pointer {beta}-arrestin2 interaction with endoglin is required for ERK/c-Myc repression. Black-Right-Pointing-Pointer Endoglin impedes cellular proliferation by targeting ERK-induced mitogenic signaling. -- Abstract: Endoglin is an endothelial-specific transforming growth factor beta (TGF-{beta}) co-receptor essential for angiogenesis and vascular remodeling. Endoglin regulates a wide range of cellular processes, including cell adhesion, migration, and proliferation, through TGF-{beta} signaling to canonical Smad and Smad-independent pathways. Despite its overall pro-angiogenic role in the vasculature, the underlying mechanism of endoglin action is poorly characterized. We previouslymore » identified {beta}-arrestin2 as a binding partner that causes endoglin internalization from the plasma membrane and inhibits ERK signaling towards endothelial migration. In the present study, we examined the mechanistic role of endoglin and {beta}-arrestin2 in endothelial cell proliferation. We show that endoglin impedes cell growth through sustained inhibition of ERK-induced c-Myc and cyclin D1 expression in a TGF-{beta}-independent manner. The down-regulation of c-Myc and cyclin D1, along with growth-inhibition, are reversed when the endoglin/{beta}-arrestin2 interaction is disrupted. Given that TGF-{beta}-induced Smad signaling potently represses c-Myc in most cell types, our findings here show a novel mechanism by which endoglin augments growth-inhibition by targeting ERK and key downstream mitogenic substrates.« less

Drosophila insulin and target of rapamycin (TOR) pathways regulate GSK3 beta activity to control Myc stability and determine Myc expression in vivo.

PubMed

Parisi, Federica; Riccardo, Sara; Daniel, Margaret; Saqcena, Mahesh; Kundu, Nandini; Pession, Annalisa; Grifoni, Daniela; Stocker, Hugo; Tabak, Esteban; Bellosta, Paola

2011-09-27

Genetic studies in Drosophila melanogaster reveal an important role for Myc in controlling growth. Similar studies have also shown how components of the insulin and target of rapamycin (TOR) pathways are key regulators of growth. Despite a few suggestions that Myc transcriptional activity lies downstream of these pathways, a molecular mechanism linking these signaling pathways to Myc has not been clearly described. Using biochemical and genetic approaches we tried to identify novel mechanisms that control Myc activity upon activation of insulin and TOR signaling pathways. Our biochemical studies show that insulin induces Myc protein accumulation in Drosophila S2 cells, which correlates with a decrease in the activity of glycogen synthase kinase 3-beta (GSK3β ) a kinase that is responsible for Myc protein degradation. Induction of Myc by insulin is inhibited by the presence of the TOR inhibitor rapamycin, suggesting that insulin-induced Myc protein accumulation depends on the activation of TOR complex 1. Treatment with amino acids that directly activate the TOR pathway results in Myc protein accumulation, which also depends on the ability of S6K kinase to inhibit GSK3β activity. Myc upregulation by insulin and TOR pathways is a mechanism conserved in cells from the wing imaginal disc, where expression of Dp110 and Rheb also induces Myc protein accumulation, while inhibition of insulin and TOR pathways result in the opposite effect. Our functional analysis, aimed at quantifying the relative contribution of Myc to ommatidial growth downstream of insulin and TOR pathways, revealed that Myc activity is necessary to sustain the proliferation of cells from the ommatidia upon Dp110 expression, while its contribution downstream of TOR is significant to control the size of the ommatidia. Our study presents novel evidence that Myc activity acts downstream of insulin and TOR pathways to control growth in Drosophila. At the biochemical level we found that both these pathways

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.

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

c-Myc dependent expression of pro-apoptotic Bim renders HER2-overexpressing breast cancer cells dependent on anti-apoptotic Mcl-1.

PubMed

Campone, Mario; Noël, Bélinda; Couriaud, Cécile; Grau, Morgan; Guillemin, Yannis; Gautier, Fabien; Gouraud, Wilfried; Charbonnel, Catherine; Campion, Loïc; Jézéquel, Pascal; Braun, Frédérique; Barré, Benjamin; Coqueret, Olivier; Barillé-Nion, Sophie; Juin, Philippe

2011-09-07

Anti-apoptotic signals induced downstream of HER2 are known to contribute to the resistance to current treatments of breast cancer cells that overexpress this member of the EGFR family. Whether or not some of these signals are also involved in tumor maintenance by counteracting constitutive death signals is much less understood. To address this, we investigated what role anti- and pro-apoptotic Bcl-2 family members, key regulators of cancer cell survival, might play in the viability of HER2 overexpressing breast cancer cells. We used cell lines as an in vitro model of HER2-overexpressing cells in order to evaluate how anti-apoptotic Bcl-2, Bcl-xL and Mcl-1, and pro-apoptotic Puma and Bim impact on their survival, and to investigate how the constitutive expression of these proteins is regulated. Expression of the proteins of interest was confirmed using lysates from HER2-overexpressing tumors and through analysis of publicly available RNA expression data. We show that the depletion of Mcl-1 is sufficient to induce apoptosis in HER2-overexpressing breast cancer cells. This Mcl-1 dependence is due to Bim expression and it directly results from oncogenic signaling, as depletion of the oncoprotein c-Myc, which occupies regions of the Bim promoter as evaluated in ChIP assays, decreases Bim levels and mitigates Mcl-1 dependence. Consistently, a reduction of c-Myc expression by inhibition of mTORC1 activity abrogates occupancy of the Bim promoter by c-Myc, decreases Bim expression and promotes tolerance to Mcl-1 depletion. Western blot analysis confirms that naïve HER2-overexpressing tumors constitutively express detectable levels of Mcl-1 and Bim, while expression data hint on enrichment for Mcl-1 transcripts in these tumors. This work establishes that, in HER2-overexpressing tumors, it is necessary, and maybe sufficient, to therapeutically impact on the Mcl-1/Bim balance for efficient induction of cancer cell death.

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.

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.

c-Myc inhibits myoblast differentiation and promotes myoblast proliferation and muscle fibre hypertrophy by regulating the expression of its target genes, miRNAs and lincRNAs.

PubMed

Luo, Wen; Chen, Jiahui; Li, Limin; Ren, Xueyi; Cheng, Tian; Lu, Shiyi; Lawal, Raman Akinyanju; Nie, Qinghua; Zhang, Xiquan; Hanotte, Olivier

2018-05-21

The transcription factor c-Myc is an important regulator of cellular proliferation, differentiation and embryogenesis. While c-Myc can inhibit myoblast differentiation, the underlying mechanisms remain poorly understood. Here, we found that c-Myc does not only inhibits myoblast differentiation but also promotes myoblast proliferation and muscle fibre hypertrophy. By performing chromatin immunoprecipitation and high-throughput sequencing (ChIP-seq), we identified the genome-wide binding profile of c-Myc in skeletal muscle cells. c-Myc achieves its regulatory effects on myoblast proliferation and differentiation by targeting the cell cycle pathway. Additionally, c-Myc can regulate cell cycle genes by controlling miRNA expression of which dozens of miRNAs can also be regulated directly by c-Myc. Among these c-Myc-associated miRNAs (CAMs), the roles played by c-Myc-induced miRNAs in skeletal muscle cells are similar to those played by c-Myc, whereas c-Myc-repressed miRNAs play roles that are opposite to those played by c-Myc. The cell cycle, ERK-MAPK and Akt-mediated pathways are potential target pathways of the CAMs during myoblast differentiation. Interestingly, we identified four CAMs that can directly bind to the c-Myc 3' UTR and inhibit c-Myc expression, suggesting that a negative feedback loop exists between c-Myc and its target miRNAs during myoblast differentiation. c-Myc also potentially regulates many long intergenic noncoding RNAs (lincRNAs). Linc-2949 and linc-1369 are directly regulated by c-Myc, and both lincRNAs are involved in the regulation of myoblast proliferation and differentiation by competing for the binding of muscle differentiation-related miRNAs. Our findings do not only provide a genome-wide overview of the role the c-Myc plays in skeletal muscle cells but also uncover the mechanism of how c-Myc and its target genes regulate myoblast proliferation and differentiation, and muscle fibre hypertrophy.

Human RNA polymerase II associated factor 1 complex promotes tumorigenesis by activating c-MYC transcription in non-small cell lung cancer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhi, Xiuyi; Giroux-Leprieur, Etienne; Respiratory Diseases and Thoracic Oncology Department, Ambroise Pare Hospital – APHP, Versailles Saint Quentin en Yvelines University, 9 Avenue Charles de Gaulle, 92100, Boulogne-Billancourt

2015-10-02

Human RNA polymerase II (RNAPII)-associated factor 1 complex (hPAF1C) plays a crucial role in protein-coding gene transcription. Overexpression of hPAF1C has been implicated in the initiation and progression of various human cancers. However, the molecular pathways involved in tumorigenesis through hPAF1C remain to be elucidated. The current study suggested hPAF1C expression as a prognostic biomarker for early stage non-small cell lung cancer (NSCLC) and patients with low hPAF1C expression levels had significantly better overall survival. Furthermore, the expression of hPAF1C was found to be positively correlated with c-MYC expression in patient tumor samples and in cancer cell lines. Mechanistic studiesmore » indicated that hPAF1C could promote lung cancer cell proliferation through regulating c-MYC transcription. These results demonstrated the prognostic value of hPAF1C in early-stage NSCLC and the role of hPAF1C in the transcriptional regulation of c-MYC oncogene during NSCLC tumorigenesis. - Highlights: • hPAF1C expression is a prognostic biomarker for early stage non-small cell lung cancer. • The expression of hPAF1C was positively correlated with c-MYC in tumor samples of patients and in several NSCLC cell lines. • hPAF1C could promote lung cancer cell proliferation through regulating c-MYC transcription.« less

c-Myc and AMPK Control Cellular Energy Levels by Cooperatively Regulating Mitochondrial Structure and Function

PubMed Central

Edmunds, Lia R.; Sharma, Lokendra; Wang, Huabo; Kang, Audry; d’Souza, Sonia; Lu, Jie; McLaughlin, Michael; Dolezal, James M.; Gao, Xiaoli; Weintraub, Susan T.; Ding, Ying; Zeng, Xuemei; Yates, Nathan; Prochownik, Edward V.

2015-01-01

The c-Myc (Myc) oncoprotein and AMP-activated protein kinase (AMPK) regulate glycolysis and oxidative phosphorylation (Oxphos) although often for different purposes. Because Myc over-expression depletes ATP with the resultant activation of AMPK, we explored the potential co-dependency of and cross-talk between these proteins by comparing the consequences of acute Myc induction in ampk+/+ (WT) and ampk-/- (KO) murine embryo fibroblasts (MEFs). KO MEFs showed a higher basal rate of glycolysis than WT MEFs and an appropriate increase in response to activation of a Myc-estrogen receptor (MycER) fusion protein. However, KO MEFs had a diminished ability to increase Oxphos, mitochondrial mass and reactive oxygen species in response to MycER activation. Other differences between WT and KO MEFs, either in the basal state or following MycER induction, included abnormalities in electron transport chain function, levels of TCA cycle-related oxidoreductases and cytoplasmic and mitochondrial redox states. Transcriptional profiling of pathways pertinent to glycolysis, Oxphos and mitochondrial structure and function also uncovered significant differences between WT and KO MEFs and their response to MycER activation. Finally, an unbiased mass-spectrometry (MS)-based survey capable of quantifying ~40% of all mitochondrial proteins, showed about 15% of them to be AMPK- and/or Myc-dependent in their steady state. Significant differences in the activities of the rate-limiting enzymes pyruvate kinase and pyruvate dehydrogenase, which dictate pyruvate and acetyl coenzyme A abundance, were also differentially responsive to Myc and AMPK and could account for some of the differences in basal metabolite levels that were also detected by MS. Thus, Myc and AMPK are highly co-dependent and appear to engage in significant cross-talk across numerous pathways which support metabolic and ATP-generating functions. PMID:26230505

Clinical relevance of TRKA expression on neuroblastoma: comparison with N-MYC amplification and CD44 expression.

PubMed Central

Combaret, V.; Gross, N.; Lasset, C.; Balmas, K.; Bouvier, R.; Frappaz, D.; Beretta-Brognara, C.; Philip, T.; Favrot, M. C.; Coll, J. L.

1997-01-01

TRKA expression was evaluated on 122 untreated neuroblastomas by immunohistochemistry using an antibody with predetermined specificity. This procedure is simple and reliable for protein detection at cellular level in a routine clinical setting. Fourteen tumours were classified as benign ganglioneuroma with a restricted expression of TRKA on ganglion cells; these patients were excluded from the following analysis. A total of 108 tumours were classified as neuroblastoma or ganglioneuroblastoma; 74 expressed TRKA protein, which strongly correlated with low stage, absence of N-MYC amplification, age (<1 year), CD44 expression and favourable clinical outcome. In a univariate analysis including tumour stage, age, histology, N-MYC amplification, CD44 and TRKA expression, all parameters had significant prognostic value. The absence of TRKA expression on CD44-positive or N-MYC non-amplified tumours permits the characterization of a subgroup of patients with intermediate prognosis. However, in a multivariate analysis taking into consideration the prognostic factors mentioned above, CD44 and tumour stage were the only independent prognostic factors for the prediction of patients' event-free survival. PMID:9099963

Selective inhibition of c-Myc/Max dimerization and DNA binding by small molecules.

PubMed

Kiessling, Anke; Sperl, Bianca; Hollis, Angela; Eick, Dirk; Berg, Thorsten

2006-07-01

bZip and bHLHZip protein family members comprise a large fraction of eukaryotic transcription factors and need to bind DNA in order to exert most of their fundamental biological roles. Their binding to DNA requires homo- or heterodimerization via alpha-helical domains, which generally do not contain obvious binding sites for small molecules. We have identified two small molecules, dubbed Mycro1 and Mycro2, which inhibit the protein-protein interactions between the bHLHZip proteins c-Myc and Max. Mycros are the first inhibitors of c-Myc/Max dimerization, which have been demonstrated to inhibit DNA binding of c-Myc with preference over other dimeric transcription factors in vitro. Mycros inhibit c-Myc-dependent proliferation, gene transcription, and oncogenic transformation in the low micromolar concentration range. Our data support the idea that dimeric transcription factors can be druggable even in the absence of obvious small-molecule binding pockets.

Glutathione Depletion Induced by c-Myc Downregulation Triggers Apoptosis on Treatment with Alkylating Agents1

PubMed Central

Biroccio, Annamaria; Benassi, Barbara; Fiorentino, Francesco; Zupi, Gabriella

2004-01-01

Abstract Here we investigate the mechanism(s) involved in the c-Myc-dependent drug response of melanoma cells. By using three M14-derived c-Myc low-expressing clones, we demonstrate that alkylating agents, cisplatin and melphalan, trigger apoptosis in the c-Myc antisense transfectants, but not in the parental line. On the contrary, topoisomerase inhibitors, adriamycin and camptothecin, induce apoptosis to the same extent regardless of c-Myc expression. Because we previously demonstrated that c-Myc downregulation decreases glutathione (GSH) content, we evaluated the role of GSH in the apoptosis induced by the different drugs. In control cells treated with one of the alkylating agents or the others, GSH depletion achieved by l-buthionine-sulfoximine preincubation opens the apoptotic pathway. The apoptosis proceeded through early Bax relocalization, cytochrome c release, and concomitant caspase-9 activation, whereas reactive oxygen species production and alteration of mitochondria membrane potential were late events. That GSH was determining in the c-Myc-dependent drug-induced apoptosis was demonstrated by altering the intracellular GSH content of the c-Myc low-expressing cells up to the level of controls. Indeed, GSH ethyl ester-mediated increase of GSH abrogated apoptosis induced by cisplatin and melphalan by inhibition of Bax/cytochrome c redistribution. The relationship among c-Myc, GSH content, and the response to alkylating agent has been also evaluated in the M14 Myc overexpressing clones as well as in the melanoma JR8 c-Myc antisense transfectants. All together, these results demonstrate that GSH plays a key role in governing c-Myc-dependent drug-induced apoptosis. PMID:15153331

Aspirin regulation of c-myc and cyclinD1 proteins to overcome tamoxifen resistance in estrogen receptor-positive breast cancer cells.

PubMed

Cheng, Ran; Liu, Ya-Jing; Cui, Jun-Wei; Yang, Man; Liu, Xiao-Ling; Li, Peng; Wang, Zhan; Zhu, Li-Zhang; Lu, Si-Yi; Zou, Li; Wu, Xiao-Qin; Li, Yu-Xia; Zhou, You; Fang, Zheng-Yu; Wei, Wei

2017-05-02

Tamoxifen is still the most commonly used endocrine therapy drug for estrogen receptor (ER)-positive breast cancer patients and has an excellent outcome, but tamoxifen resistance remains a great impediment to successful treatment. Recent studies have prompted an anti-tumor effect of aspirin. Here, we demonstrated that aspirin not only inhibits the growth of ER-positive breast cancer cell line MCF-7, especially when combined with tamoxifen, but also has a potential function to overcome tamoxifen resistance in MCF-7/TAM. Aspirin combined with tamoxifen can down regulate cyclinD1 and block cell cycle in G0/G1 phase. Besides, tamoxifen alone represses c-myc, progesterone receptor (PR) and cyclinD1 in MCF-7 cell line but not in MCF-7/TAM, while aspirin combined with tamoxifen can inhibit the expression of these proteins in the resistant cell line. When knocking down c-myc in MCF-7/TAM, cells become more sensitive to tamoxifen, cell cycle is blocked as well, indicating that aspirin can regulate c-myc and cyclinD1 proteins to overcome tamoxifen resistance. Our study discovered a novel role of aspirin based on its anti-tumor effect, and put forward some kinds of possible mechanisms of tamoxifen resistance in ER-positive breast cancer cells, providing a new strategy for the treatment of ER-positive breast carcinoma.

Elevation of c-MYC Disrupts HLA Class II-mediated Immune Recognition of Human B-cell Tumors1

PubMed Central

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

2014-01-01

Elevated levels of the transcription factor c-myc are strongly associated with various cancers, and in particular B-cell lymphomas. While many of c-MYC’s functions have been elucidated, its effect on the presentation of antigen (Ag) through the HLA class II pathway has not previously been reported. This is an issue of considerable importance, given the low immunogenicity of many c-MYC-positive tumors. We report here that increased c-MYC expression has a negative effect on the ability of B-cell lymphomas to functionally present Ags/peptides to CD4+ T cells. This defect was associated with alterations in the expression of distinct co-factors as well as interactions of antigenic peptides with class II molecules required for the presentation of class II-peptide complexes and T cell engagement. Using early passage Burkitt’s lymphoma (BL) tumors and transformed cells, we show that compared to B-lymphoblasts, BL cells express decreased levels of the class II editor HLA-DM, lysosomal thiol-reductase GILT, and a 47kDa enolase-like protein. Functional Ag presentation was partially restored in BL cells treated with a c-MYC inhibitor, demonstrating the impact of this oncogene on Ag recognition. This restoration of HLA class II-mediated Ag presentation in early passage BL tumors/cells was linked to enhanced HLA-DM expression and a concurrent decrease in HLA-DO in BL cells. Taken together, these results reveal c-MYC exerts suppressive effects at several critical checkpoints in Ag presentation which contribute to the immunoevasive properties of BL tumors. PMID:25595783

The inhibition of c-MYC transcription factor modulates the expression of glycolytic and glutaminolytic enzymes in FaDu hypopharyngeal carcinoma cells.

PubMed

Kleszcz, Robert; Paluszczak, Jarosław; Krajka-Kuźniak, Violetta; Baer-Dubowska, Wanda

2018-05-17

Cancer cells are dependent on aerobic glycolysis for energy production and increased glutamine consumption. HIF-1α and c-MYC transcription factors regulate the expression of glycolytic and glutaminolytic genes. Their activity may be repressed by SIRT6. Head and neck carcinomas show frequent activation of c-MYC function and SIRT6 down-regulation, which contributes to a strong dependence on glucose and glutamine availability. The aim of this study was to compare the influence of HIF-1α and c-MYC inhibitors (KG-548 and 10058-F4, respectively) and potential SIRT6 inducers - resveratrol and its synthetic derivative DMU-212 with the effect of glycolysis and glutaminolysis inhibitors (2-deoxyglucose and aminooxyacetic acid, respectively) on the metabolism and expression of metabolic enzymes in FaDu hypopharyngeal carcinoma cells. Cell viability was assessed by means of an MTT assay. Quantitative PCR was performed to evaluate the expression of SIRT6, HIF-1α, c-MYC, GLUT1, SLC1A5, HK2, PFKM, PKM2, LDHA, GLS, and GDH. The release of glycolysis and glutaminolysis end-products into the culture medium - lactate and ammonia, respectively - was assessed using standard colorimetric assays. Lactate production was significantly inhibited by 10058-F4, KG-548, and 2-deoxyglucose. Moreover, 10058-F4 strongly reduced the amount of ammonia release. The effects of 10058-F4 activity can be attributed to a reduction in the expression of PKM2 and LDHA. On the other hand, the induction of SIRT6 expression by resveratrol and DMU-212 was not associated with significant modulation of the expression of metabolic enzymes. Overall, the results of this study indicate that the inhibition of c-MYC may be considered to be a promising strategy of the modulation of cancer-related metabolic changes in head and neck carcinomas.

Sequential treatment with aurora B inhibitors enhances cisplatin-mediated apoptosis via c-Myc.

PubMed

Ma, Yaxi; Cao, Handi; Lou, Siyue; Shao, Xuejing; Lv, Wen; Qi, Xiaotian; Liu, Yujia; Ying, Meidan; He, Qiaojun; Yang, Xiaochun

2015-04-01

Platinum compound such as cisplatin is the first-line chemotherapy of choice in most patients with ovarian carcinoma. However, patients with inherent or acquired cisplatin resistance often experience relapse. Therefore, novel therapies are urgently required to treat drug-resistant ovarian carcinoma. Here, we showed that compared to the non-functional traditional simultaneous treatment, sequential combination of Aurora B inhibitors followed by cisplatin synergistically enhanced apoptotic response in cisplatin-resistant OVCAR-8 cells. This effect was accompanied by the induction of polyploidy in a c-Myc-dependent manner, as c-Myc knockdown reduced the efficacy of the combination by suppressing the expression of Aurora B and impairing cellular response to Aurora B inhibitor, as indicated by the decreased polyploidy and hyperphosphorylation of histone H1. In c-Myc-deficient SKOV3 cells, c-Myc overexpression restored Aurora B expression, induced polyploidy after inhibition of Aurora B, and sensitized cells to this combination therapy. Thus, our report reveals for the first time that sequential treatment of Aurora B inhibitors and cisplatin is essential to inhibit ovarian carcinoma by inducing polyploidy and downregulating c-Myc and that c-Myc is identified as a predictive biomarker to select cells responsive to chemotherapeutical combinations targeting Aurora B. Collectively, these studies provide novel approaches to overcoming cisplatin chemotherapy resistance in ovarian cancer. Pretreatment of Aurora B inhibitors augment apoptotic effects of cisplatin. The synergy of Aurora B inhibitor with cisplatin is dependent on c-Myc expression. c-Myc-dependent induction of polyploidy sensitizes cells to cisplatin.

Early induction of c-Myc is associated with neuronal cell death.

PubMed

Lee, Hyun-Pil; Kudo, Wataru; Zhu, Xiongwei; Smith, Mark A; Lee, Hyoung-gon

2011-11-14

Neuronal cell cycle activation has been implicated in neurodegenerative diseases such as Alzheimer's disease, while the initiating mechanism of cell cycle activation remains to be determined. Interestingly, our previous studies have shown that cell cycle activation by c-Myc (Myc) leads to neuronal cell death which suggests Myc might be a key regulator of cell cycle re-entry mediated neuronal cell death. However, the pattern of Myc expression in the process of neuronal cell death has not been addressed. To this end, we examined Myc induction by the neurotoxic agents camptothecin and amyloid-β peptide in a differentiated SH-SY5Y neuronal cell culture model. Myc expression was found to be significantly increased following either treatment and importantly, the induction of Myc preceded neuronal cell death suggesting it is an early event of neuronal cell death. Since ectopic expression of Myc in neurons causes the cell cycle activation and neurodegeneration in vivo, the current data suggest that induction of Myc by neurotoxic agents or other disease factors might be a key mediator in cell cycle activation and consequent cell death that is a feature of neurodegenerative diseases. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

Molecular cloning, structural analysis, and expression of a human IRLB, MYC promoter-binding protein: new DENN domain-containing protein family emerges.

PubMed

Semova, Natalia; Kapanadze, Bagrat; Corcoran, Martin; Kutsenko, Alexei; Baranova, Ancha; Semov, Alexandre

2003-09-01

IRLB was originally identified as a partial cDNA clone, encoding a 191-aa protein binding the interferon-stimulated response element (ISRE) in the P2 promoter of human MYC. Here, we cloned the full-size IRLB using different bioinformatics tools and an RT-PCR approach. The full-size gene encompasses 131 kb within chromosome 15q22 and consists of 32 exons. IRLB is transcribed as a 6.6-kb mRNA encoding a protein of 1865 aa. IRLB is ubiquitously expressed and its expression is regulated in a growth- and cell cycle-dependent manner. In addition to the ISRE-binding domain IRLB contains a tripartite DENN domain, a nuclear localization signal, two PPRs, and a calmodulin-binding domain. The presence of DENN domains predicts possible interactions of IRLB with GTPases from the Rab family or regulation of growth-induced MAPKs. Strongly homologous proteins were identified in all available vertebrate genomes as well as in Caenorhabditis elegans and Drosophila melanogaster. In human and mouse a family of IRLB proteins exists, consisting of at least three members.

Phosphatidylcholine hydrolysis and c-myc expression are in collaborating mitogenic pathways activated by colony-stimulating factor 1.

PubMed

Xu, X X; Tessner, T G; Rock, C O; Jackowski, S

1993-03-01

Stimulation of diglyceride production via phospholipase C (PLC) hydrolysis of phosphatidylcholine was an early event in the mitogenic action of colony-stimulating factor 1 (CSF-1) in the murine macrophage cell line BAC1.2F5 and was followed by a second phase of diglyceride production that persisted throughout the G1 phase of the cell cycle. Addition of phosphatidylcholine-specific PLC (PC-PLC) from Bacillus cereus to the medium of quiescent cells raised the intracellular diglyceride concentration and stimulated [3H]thymidine incorporation, although PC-PLC did not support continuous proliferation. PC-PLC treatment did not induce tyrosine phosphorylation or turnover of the CSF-1 receptor. The major protein kinase C (PKC) isotype in BAC1.2F5 cells was PKC-delta. Diglyceride production from PC-PLC did not target PKC-delta, since unlike phorbol esters, PC-PLC treatment neither decreased the electrophoretic mobility of PKC-delta nor increased the amount of GTP bound to Ras, and PC-PLC was mitogenically active in BAC1.2F5 cells in which PKC-delta was downregulated by prolonged treatment with phorbol ester. PC-PLC mimicked CSF-1 action by elevating c-fos and junB mRNAs to 40% of the level induced by CSF-1; however, PC-PLC induced c-myc mRNA to only 5% of the level in CSF-1-stimulated cells. PC-PLC addition to CSF-1-dependent BAC1.2F5 clones that constitutively express c-myc increased [3H]thymidine incorporation to 86% of the level evoked by CSF-1 and supported slow growth in the absence of CSF-1. Therefore, PC-PLC is a component of a signal transduction pathway leading to transcription of c-fos and junB that collaborates with c-myc and is independent of PKC-delta and Ras activation.

Tumor suppressor NDRG2 inhibits glycolysis and glutaminolysis in colorectal cancer cells by repressing c-Myc expression

PubMed Central

Chu, Dake; Wei, Li; Li, Xia; Yang, Guodong; Liu, Xinping; Yao, Libo; Zhang, Jian; Shen, Lan

2015-01-01

Cancer cells use glucose and glutamine as the major sources of energy and precursor intermediates, and enhanced glycolysis and glutamimolysis are the major hallmarks of metabolic reprogramming in cancer. Oncogene activation and tumor suppressor gene inactivation alter multiple intracellular signaling pathways that affect glycolysis and glutaminolysis. N-Myc downstream regulated gene 2 (NDRG2) is a tumor suppressor gene inhibiting cancer growth, metastasis and invasion. However, the role and molecular mechanism of NDRG2 in cancer metabolism remains unclear. In this study, we discovered the role of the tumor suppressor gene NDRG2 in aerobic glycolysis and glutaminolysis of cancer cells. NDRG2 inhibited glucose consumption and lactate production, glutamine consumption and glutamate production in colorectal cancer cells. Analysis of glucose transporters and the catalytic enzymes involved in glycolysis revealed that glucose transporter 1 (GLUT1), hexokinase 2 (HK2), pyruvate kinase M2 isoform (PKM2) and lactate dehydrogenase A (LDHA) was significantly suppressed by NDRG2. Analysis of glutamine transporter and the catalytic enzymes involved in glutaminolysis revealed that glutamine transporter ASC amino-acid transporter 2 (ASCT2) and glutaminase 1 (GLS1) was also significantly suppressed by NDRG2. Transcription factor c-Myc mediated inhibition of glycolysis and glutaminolysis by NDRG2. More importantly, NDRG2 inhibited the expression of c-Myc by suppressing the expression of β-catenin, which can transcriptionally activate C-MYC gene in nucleus. In addition, the growth and proliferation of colorectal cancer cells were suppressed significantly by NDRG2 through inhibition of glycolysis and glutaminolysis. Taken together, these findings indicate that NDRG2 functions as an essential regulator in glycolysis and glutaminolysis via repression of c-Myc, and acts as a suppressor of carcinogenesis through coordinately targeting glucose and glutamine transporter, multiple catalytic

[Relationship between the expression of beta-cat, cyclin D1 and c-myc and the occurance and biological behavior of pancreatic cancer].

PubMed

Li, Yu-jun; Ji, Xiang-rui

2003-06-01

To study the relationship between the abnormal expression of beta-catenin (beta-cat) and the high expressions of cyclin D1 and c-myc and the occurance, proliferation, infiltration, metastasis and prognosis of pancreatic cancer, and to provide rational basis for the clinical diagnosis and treatment. Immunohistochemical PicTure trade mark was used to examine the expressions of beta-cat, cyclin D1 and c-myc in 47 cases of the cancerous tissue of pancreas, 12 cases of the pancreatic intraepithelial neoplasia and 10 cases of normal tissue of pancreas, respectively. Pancreatic cancer proliferation cell nuclear antigen (PCNA) was also tested as the index of the extent of proliferation of the pancreatic cancer. beta-cat was expressed normally in the 10 cases of the normal pancreatic tissue, while cyclin D1 and c-myc were negative. The expression rates of beta-cat, cyclin D1 and c-myc in the tissues of the pancreatic intraepithelial neoplasia and the pancreatic cancer had no significant difference [6/12 and 68.1% (32/47), 6/12 and 74.5% (35/47), 5/12 and 70.2% (33/47) respectively;P values were all more than 0.05]. The abnormal expression rate of beta-cat was significantly correlated to the metastasis of the pancreatic cancer and the one-year survival rate (both P < 0.05), but had no relation with the size, the extent of differentiation, the activity of proliferation, or infiltration of the pancreatic cancer (both P > 0.05). The expression rate of cyclin D1 was correlated with the proliferation of the pancreatic cancer and the extent of differentiation (both P < 0.05), but not with the size, infiltration, metastasis, or one-year survival rate of the pancreatic cancer (both P > 0.05). The expression rate of c-myc was not correlated with the size, the extent of proliferation, infiltration, metastasis, or one-year survival rate (both P > 0.05), but closely with the proliferation activity of the cancerous tissue of pancreas (P < 0.05). The abnormal expression of beta-cat and

MYC-induced cancer cell energy metabolism and therapeutic opportunities.

PubMed

Dang, Chi V; Le, Anne; Gao, Ping

2009-11-01

Although cancers have altered glucose metabolism, termed the Warburg effect, which describes the increased uptake and conversion of glucose to lactate by cancer cells under adequate oxygen tension, changes in the metabolism of glutamine and fatty acid have also been documented. The MYC oncogene, which contributes to the genesis of many human cancers, encodes a transcription factor c-Myc, which links altered cellular metabolism to tumorigenesis. c-Myc regulates genes involved in the biogenesis of ribosomes and mitochondria, and regulation of glucose and glutamine metabolism. With E2F1, c-Myc induces genes involved in nucleotide metabolism and DNA replication, and microRNAs that homeostatically attenuate E2F1 expression. With the hypoxia inducible transcription factor HIF-1, ectopic c-Myc cooperatively induces a transcriptional program for hypoxic adaptation. Myc regulates gene expression either directly, such as glycolytic genes including lactate dehydrogenase A (LDHA), or indirectly, such as repression of microRNAs miR-23a/b to increase glutaminase (GLS) protein expression and glutamine metabolism. Ectopic MYC expression in cancers, therefore, could concurrently drive aerobic glycolysis and/or oxidative phosphorylation to provide sufficient energy and anabolic substrates for cell growth and proliferation in the context of the tumor microenvironment. Collectively, these studies indicate that Myc-mediated altered cancer cell energy metabolism could be translated for the development of new anticancer therapies.

Repression of miR-17-5p with elevated expression of E2F-1 and c-MYC in non-metastatic hepatocellular carcinoma and enhancement of cell growth upon reversing this expression pattern

DOE Office of Scientific and Technical Information (OSTI.GOV)

El Tayebi, H.M.; Omar, K.; Hegy, S.

2013-05-10

Highlights: •The oncogenic miR-17-5p is downregulated in non-metastatic hepatocellular carcinoma patients. •E2F-1 and c-MYC transcripts are upregulated in non-metastatic HCC patients. •miR-17-5p forced overexpression inhibited E2F-1 and c-MYC expression in HuH-7 cells. •miR-17-5p mimicking increased HuH-7 cell growth, proliferation, migration and colony formation. •miR-17-5p is responsible for HCC progression among the c-MYC/E2F-1/miR-17-5p triad members. -- Abstract: E2F-1, c-MYC, and miR-17-5p is a triad of two regulatory loops: a negative and a positive loop, where c-MYC induces the expression of E2F-1 that induces the expression of miR-17-5p which in turn reverses the expression of E2F-1 to close the loop. In thismore » study, we investigated this triad for the first time in hepatocellular carcinoma (HCC), where miR-17-5p showed a significant down-regulation in 23 non-metastatic HCC biopsies compared to 10 healthy tissues; however, E2F-1 and c-MYC transcripts were markedly elevated. Forced over-expression of miR-17-5p in HuH-7 cells resulted in enhanced cell proliferation, growth, migration and clonogenicity with concomitant inhibition of E2F-1 and c-MYC transcripts expressions, while antagomirs of miR-17-5p reversed these events. In conclusion, this study revealed a unique pattern of expression for miR-17-5p in non-metastatic HCC patients in contrast to metastatic HCC patients. In addition we show that miR-17-5p is the key player among the triad that tumor growth and spread.« less

Targeting of the MYCN Protein with Small Molecule c-MYC Inhibitors

PubMed Central

Müller, Inga; Larsson, Karin; Frenzel, Anna; Oliynyk, Ganna; Zirath, Hanna; Prochownik, Edward V.; Westwood, Nicholas J.; Henriksson, Marie Arsenian

2014-01-01

Members of the MYC family are the most frequently deregulated oncogenes in human cancer and are often correlated with aggressive disease and/or poorly differentiated tumors. Since patients with MYCN-amplified neuroblastoma have a poor prognosis, targeting MYCN using small molecule inhibitors could represent a promising therapeutic approach. We have previously demonstrated that the small molecule 10058-F4, known to bind to the c-MYC bHLHZip dimerization domain and inhibiting the c-MYC/MAX interaction, also interferes with the MYCN/MAX dimerization in vitro and imparts anti-tumorigenic effects in neuroblastoma tumor models with MYCN overexpression. Our previous work also revealed that MYCN-inhibition leads to mitochondrial dysfunction resulting in accumulation of lipid droplets in neuroblastoma cells. To expand our understanding of how small molecules interfere with MYCN, we have now analyzed the direct binding of 10058-F4, as well as three of its analogs; #474, #764 and 10058-F4(7RH), one metabolite C-m/z 232, and a structurally unrelated c-MYC inhibitor 10074-G5, to the bHLHZip domain of MYCN. We also assessed their ability to induce apoptosis, neurite outgrowth and lipid accumulation in neuroblastoma cells. Interestingly, all c-MYC binding molecules tested also bind MYCN as assayed by surface plasmon resonance. Using a proximity ligation assay, we found reduced interaction between MYCN and MAX after treatment with all molecules except for the 10058-F4 metabolite C-m/z 232 and the non-binder 10058-F4(7RH). Importantly, 10074-G5 and 10058-F4 were the most efficient in inducing neuronal differentiation and lipid accumulation in MYCN-amplified neuroblastoma cells. Together our data demonstrate MYCN-binding properties for a selection of small molecules, and provide functional information that could be of importance for future development of targeted therapies against MYCN-amplified neuroblastoma. PMID:24859015

Course of c-myc mRNA expression in the regenerating mouse testis determined by competitive reverse transcriptase polymerase chain reaction.

PubMed

Amendola, R

1994-11-01

The c-myc proto-oncogene is a reliable marker of the "G0-early G1" transition, and its down-regulation is believed to be necessary to obtain cellular differentiation. In murine spermatogenesis, the level of c-myc transcripts does not correlate with the rate of cellular division. Proliferation of supposed staminal spermatogonia to reproduce themselves is induced with a local 5 Gy X-ray dose in 90-day-old C57Bl/6 mice. c-myc quantification by a newly developed competitive reverse transcriptase polymerase chain reaction (RT-PCR) was carried out to follow the expression course of this proto-oncogene. Damage and restoration of spermatogenesis were analyzed at days 3, 6, 9, 10, 13, 30, and 60 after injury by relative testes/body weight determination and histological examination. Proliferative status was determined by histone H3 Northern blot analysis. c-myc mRNA level was 10 times higher after 3 days in the irradiated animals compared to the controls. An increasing number of copies were noted up to 10 days, but promptly decreased to the base level found for irradiated mice from 13 to 60 days. Interestingly, the expression of histone H3 detected S phase only in testes at 60 days from damage.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Bo; Hikosaka, Keisuke; Sultana, Nishat

2012-01-06

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

Mxi1 is a repressor of the c-Myc promoter and reverses activation by USF.

PubMed

Lee, T C; Ziff, E B

1999-01-08

The basic region/helix-loop-helix/leucine zipper (B-HLH-LZ) oncoprotein c-Myc is abundant in proliferating cells and forms heterodimers with Max protein that bind to E-box sites in DNA and stimulate genes required for proliferation. A second B-HLH-LZ protein, Mxi1, is induced during terminal differentiation, and forms heterodimers with Max that also bind E-boxes but tether the mSin3 transcriptional repressor protein along with histone deacetylase thereby antagonizing Myc-dependent activation. We show that Mxi1 also antagonizes Myc by a second pathway, repression of transcription from the major c-myc promoter, P2. Repression was independent of Mxi1 binding to mSin3 but dependent on the Mxi1 LZ and COOH-terminal sequences, including putative casein kinase II phosphorylation sites. Repression targeted elements of the myc P2 promoter core (-35/+10), where it reversed transactivation by the constitutive transcription factor, USF. We show that Zn2+ induction of a stably transfected, metallothionein promoter-regulated mxi1 gene blocked the ability of serum to induce transcription of the endogenous c-myc gene and cell entry into S phase. Thus, induction of Mxi1 in terminally differentiating cells may block Myc function by repressing the c-myc gene P2 promoter, as well as by antagonizing Myc-dependent transactivation through E-boxes.

Inhibition of bromodomain and extra-terminal (BET) proteins increases NKG2D ligand MICA expression and sensitivity to NK cell-mediated cytotoxicity in multiple myeloma cells: role of cMYC-IRF4-miR-125b interplay.

PubMed

Abruzzese, Maria Pia; Bilotta, Maria Teresa; Fionda, Cinzia; Zingoni, Alessandra; Soriani, Alessandra; Vulpis, Elisabetta; Borrelli, Cristiana; Zitti, Beatrice; Petrucci, Maria Teresa; Ricciardi, Maria Rosaria; Molfetta, Rosa; Paolini, Rossella; Santoni, Angela; Cippitelli, Marco

2016-12-01

Anti-cancer immune responses may contribute to the control of tumors after conventional chemotherapy, and different observations have indicated that chemotherapeutic agents can induce immune responses resulting in cancer cell death and immune-stimulatory side effects. Increasing experimental and clinical evidence highlight the importance of natural killer (NK) cells in immune responses toward multiple myeloma (MM), and combination therapies able to enhance the activity of NK cells against MM are showing promise in treating this hematologic cancer. The epigenetic readers of acetylated histones bromodomain and extra-terminal (BET) proteins are critical regulators of gene expression. In cancer, they can upregulate transcription of key oncogenes such as cMYC, IRF4, and BCL-2. In addition, the activity of these proteins can regulate the expression of osteoclastogenic cytokines during cancer progression. Here, we investigated the effect of BET bromodomain protein inhibition, on the expression of NK cell-activating ligands in MM cells. Five MM cell lines [SKO-007(J3), U266, RPMI-8226, ARP-1, JJN3] and CD138 + MM cells isolated from MM patients were used to investigate the activity of BET bromodomain inhibitors (BETi) (JQ1 and I-BET151) and of the selective BRD4-degrader proteolysis targeting chimera (PROTAC) (ARV-825), on the expression and function of several NK cell-activating ligands (NKG2DLs and DNAM-1Ls), using flow cytometry, real-time PCR, transient transfections, and degranulation assays. Our results indicate that inhibition of BET proteins via small molecule inhibitors or their degradation via a hetero-bifunctional PROTAC probe can enhance the expression of MICA, a ligand of the NKG2D receptor, in human MM cell lines and primary malignant plasma cells, rendering myeloma cells more efficient to activate NK cell degranulation. Noteworthy, similar results were obtained using selective CBP/EP300 bromodomain inhibition. Mechanistically, we found that BETi

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

PubMed

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

2012-01-06

The retinoblastoma (Rb) tumor suppressor encodes a nuclear phosphoprotein that regulates cellular proliferation, apoptosis and differentiation. In order to adapt itself to these biological functions, Rb is subjected to modification cycle, phosphorylation and dephosphorylation. To directly determine the effect of phosphorylation-resistant Rb on liver development and function, we generated transgenic mice expressing phosphorylation-resistant human mutant Rb (mt-Rb) under the control of the rat hepatocyte nuclear factor-1 gene promoter/enhancer. Expression of mt-Rb in the liver resulted in macroscopic neoplastic nodules (adenomas) with ∼50% incidence within 15 months old. Interestingly, quantitative reverse transcriptase-PCR analysis showed that c-Myc was up-regulated in the liver of mt-Rb transgenic mice irrespective of having tumor tissues or no tumor. In tumor tissues, several c-Myc target genes, Foxm1, c-Jun, c-Fos, Bmi1 and Skp2, were also up-regulated dramatically. We determined whether mt-Rb activated the Myc promoter in the HTP9 cells and demonstrated that mt-Rb acted as an inhibitor of wild-type Rb-induced repression on the Myc promoter. Our results suggest that continued upregulation of c-Myc target genes promotes the liver tumor formation after about 1 year of age. Copyright © 2011 Elsevier Inc. All rights reserved.

c-myc as a mediator of accelerated apoptosis and involution in mammary glands lacking Socs3

PubMed Central

Sutherland, Kate D; Vaillant, François; Alexander, Warren S; Wintermantel, Tim M; Forrest, Natasha C; Holroyd, Sheridan L; McManus, Edward J; Schutz, Gunther; Watson, Christine J; Chodosh, Lewis A; Lindeman, Geoffrey J; Visvader, Jane E

2006-01-01

Suppressor of cytokine signalling (SOCS) proteins are critical attenuators of cytokine-mediated signalling in diverse tissues. To determine the importance of Socs3 in mammary development, we generated mice in which Socs3 was deleted in mammary epithelial cells. No overt phenotype was evident during pregnancy and lactation, indicating that Socs3 is not a key physiological regulator of prolactin signalling. However, Socs3-deficient mammary glands exhibited a profound increase in epithelial apoptosis and tissue remodelling, resulting in precocious involution. This phenotype was accompanied by augmented Stat3 activation and a marked increase in the level of c-myc. Moreover, induction of c-myc before weaning using an inducible transgenic model recapitulated the Socs3 phenotype, and elevated expression of likely c-myc target genes, E2F-1, Bax and p53, was observed. Our data establish Socs3 as a critical attenuator of pro-apoptotic pathways that act in the developing mammary gland and provide evidence that c-myc regulates apoptosis during involution. PMID:17139252

miR-34a increases cisplatin sensitivity of osteosarcoma cells in vitro through up-regulation of c-Myc and Bim signal.

PubMed

Li, Qi-Cai; Xu, Haiyan; Wang, Xiaohui; Wang, Ting; Wu, Jiang

2017-12-12

Osteosarcoma is the most common primary malignancy in bone. Patients who respond poorly to induction chemotherapy are at higher risk of adverse prognosis. The molecular basis for such poor prognosis remains unclear. Recently, increasing evidence has suggested decreased expression of miR-34a is observed in a number of cancer types, including human osteosarcoma, and decreased miR-34a is involved in drug resistance. However, the underlying molecular mechanisms of decreased miR-34a on cisplatin chemoresistance in osteosarcoma has not been reported. Osteosarcoma U2OS cells were transfected with miR-34a mimics for 48 h, then the cells were treated with 3.0 μm cisplatin for 24 h. Using siRNA targeting c-Myc and Bim to examine the relation between miR-34a, c-Myc and Bim expression exposure to cisplatin on cisplatin-induced apoptosis. Treatment of U2OS cells with cisplatin induced cell apoptosis by upregulation of c-Myc -dependent Bim expression; Osteosarcoma U2OS cells transfected with miR-34a mimics (miR-34a/U2OS) induced cell apoptosis and inhibited cell survival, and increased the sensitivity of U2OS cells to cisplatin. U2OS cells transfected with miR-34a mimics upregulated the protein expression of c-Myc and Bim. Targeting c-Myc downregulated the expression of Bim in the miR-34a/U2OS cells. In addition, Targeting Bim reversed the chemeresistance of miR-34a/U2OS cells to cisplatin. Our data indicated that miR-34a enhanced the sensitivity to cisplatin by upregulation of c-Myc and Bim pathway.

MYC protein expression is detected in plasma cell myeloma but not in monoclonal gammopathy of undetermined significance (MGUS).

PubMed

Xiao, Ruobing; Cerny, Jan; Devitt, Katherine; Dresser, Karen; Nath, Rajneesh; Ramanathan, Muthalagu; Rodig, Scott J; Chen, Benjamin J; Woda, Bruce A; Yu, Hongbo

2014-06-01

It has been recognized that monoclonal gammopathy of undetermined significance (MGUS) precedes a diagnosis of plasma cell myeloma in most patients. Recent gene expression array analysis has revealed that an MYC activation signature is detected in plasma cell myeloma but not in MGUS. In this study, we performed immunohistochemical studies using membrane CD138 and nuclear MYC double staining on bone marrow biopsies from patients who met the diagnostic criteria of plasma cell myeloma or MGUS. Our study demonstrated nuclear MYC expression in CD138-positive plasma cells in 22 of 26 (84%) plasma cell myeloma samples and in none of the 29 bone marrow samples from patients with MGUS. In addition, our data on the follow-up biopsies from plasma cell myeloma patients with high MYC expression demonstrated that evaluation of MYC expression in plasma cells can be useful in detecting residual disease. We also demonstrated that plasma cells gained MYC expression in 5 of 8 patients (62.5%) when progressing from MGUS to plasma cell myeloma. Analysis of additional lymphomas with plasmacytic differentiation, including lymphoplasmacytic lymphoma, marginal zone lymphoma, and plasmablastic lymphoma, reveals that MYC detection can be a useful tool in the diagnosis of plasma cell myeloma.

The effect of Glut1 and c-myc on prognosis in esophageal squamous cell carcinoma of Kazakh and Han patients.

PubMed

Zhou, Ya-Xing; Zhou, Ke-Ming; Liu, Qian; Wang, Hui; Wang, Wen; Shi, Yi; Ma, Yu-Qing

2018-04-09

Glucose transporter type 1 (Glut1) plays a crucial role in cancer-specific metabolism. We explored the expression of Glut1 and c-myc, the relationship between them and the effect of Glut1, c-myc on prognosis in esophageal squamous cell carcinoma. Immunohistochemistry was used to examine the expression of Glut1 and c-myc. χ 2 test analyzes the relationship between c-myc, Glut1 and pathological parameters. Spearman correlation analyzes the relationship between c-myc and Glut1. Survival analysis was used to investigate the effect of Glut1 and c-myc on prognosis. Glut1 positivity was associated with tumor size (p < 0.01), depth of invasion (p = 0.021), tumor, node, metastasis (TNM) stage (IA+IB,II+IIB,IIIA+IIIB,IVA+IVB ; p = 0.004), lymph node metastasis (p = 0.002) and nerve invasion (p = 0.050). C-myc positivity was associated with tumor location (p = 0.015), depth of invasion (p = 0.022) and lymph node metastasis (p = 0.035). There was a positive correlation between c-myc and Glut1 (r = 0.321). Patients with Glut1 c-myc co-expression had poorer prognosis. Inhibiting Glut1 c-myc co-expression may improve the prognosis of esophageal squamous cell carcinoma.

High levels of bcl-2 protein expression do not correlate with genetic abnormalities but predict worse prognosis in patients with lymphoblastic lymphoma.

PubMed

Gu, Yajun; Pan, Yi; Meng, Bin; Guan, Bingxin; Fu, Kai; Sun, Baocun; Zheng, Fang

2013-06-01

We aimed to investigate bcl-2, bcl-6, and c-myc rearrangements in patients with lymphoblastic lymphoma (LBL), especially focus on the correlation of protein expression with genetic abnormalities. Moreover, their prognostic significance was further analyzed in LBL. Protein expression and genetic abnormalities of bcl-2, bcl-6, and c-myc were investigated in microarrayed tumors from 33 cases of T cell LBL and eight cases of B cell lineage. Immunohistochemical (IHC) staining was performed to evaluate protein expression, including bcl-2, bcl-6, c-myc, TdT, CD1α, CD34, Ki-67, PAX-5, CD2, CD3, CD4, CD8, and CD20. Genetic abnormalities of bcl-2, bcl-6, and c-myc were detected by dual color fluorescence in situ hybridization (FISH). Bcl-2 protein was positive in 51.2 % (21/41) of the patients, bcl-6 protein in 7.3 % (three out of 41), and c-myc protein in 78.0 % (32/41). Bcl-2 breakpoint was found in two cases by FISH analysis. There was no evidence of bcl-6 or c-myc rearrangement in patients with LBL. However, both gene gain and loss events occurred in bcl-2, bcl-6, and c-myc. A univariate analysis showed that stage III or IV, elevated lactate dehydrogenase (LDH), and positivity for bcl-2 protein were associated with shorter survival (p<0.05). Enhanced protein expression and detectable genetic abnormalities of bcl-2, bcl-6, and c-myc were observed in patients with LBL. No statistical correlation was found between IHC results and cytogenetic findings. Stage III or IV, elevated LDH, and positivity for bcl-2 protein were identified as adverse prognostic factors. The patients with more adverse factors would have increasingly worse prognosis.

c-MYC G-quadruplex binding by the RNA polymerase I inhibitor BMH-21 and analogues revealed by a combined NMR and biochemical Approach.

PubMed

Musso, Loana; Mazzini, Stefania; Rossini, Anna; Castagnoli, Lorenzo; Scaglioni, Leonardo; Artali, Roberto; Di Nicola, Massimo; Zunino, Franco; Dallavalle, Sabrina

2018-03-01

Pyridoquinazolinecarboxamides have been reported as RNA polymerase I inhibitors and represent a novel class of potential antitumor agents. BMH-21, was reported to intercalate with GC-rich rDNA, resulting in nucleolar stress as a primary mechanism of cytotoxicity. The interaction of BMH-21 and analogues with DNA G-quadruplex structures was studied by NMR and molecular modelling. The cellular response was investigated in a panel of human tumor cell lines and protein expression was examined by Western Blot analysis. We explored the ability of BMH-21 and its analogue 2 to bind to G-quadruplex present in the c-MYC promoter, by NMR and molecular modelling studies. We provide evidence that both compounds are not typical DNA intercalators but are effective binders of the tested G-quadruplex. The interaction with c-MYC G-quadruplex was reflected in down-regulation of c-Myc expression in human tumor cells. The inhibitory effect was almost complete in lymphoma cells SUDHL4 characterized by overexpression of c-Myc protein. This downregulation reflected an early and persistent modulation of cMyc mRNA. Given the relevance of c-MYC in regulation of ribosome biogenesis, it is conceivable that the inhibition of c-MYC contributes to the perturbation of nuclear functions and RNA polymerase I activity. Similar experiments with CX-5461, another RNA polymerase I transcription inhibitor, indicate the same behaviour in G-quadruplex stabilization. Our results support the hypothesis that BMH-21 and analogue compounds share the same mechanism, i.e. G-quadruplex binding as a primary event of a cascade leading to inhibition of RNA polymerase I and apoptosis. Copyright © 2017 Elsevier B.V. All rights reserved.

Concurrent nuclear ERG and MYC protein overexpression defines a subset of locally advanced prostate cancer: Potential opportunities for synergistic targeted therapeutics.

PubMed

Udager, Aaron M; DeMarzo, Angelo M; Shi, Yang; Hicks, Jessica L; Cao, Xuhong; Siddiqui, Javed; Jiang, Hui; Chinnaiyan, Arul M; Mehra, Rohit

2016-06-01

Recurrent ERG gene fusions, the most common genetic alterations in prostate cancer, drive overexpression of the nuclear transcription factor ERG, and are early clonal events in prostate cancer progression. The nuclear transcription factor MYC is also frequently overexpressed in prostate cancer and may play a role in tumor initiation and/or progression. The relationship between nuclear ERG and MYC protein overexpression in prostate cancer, as well as the clinicopathologic characteristics and prognosis of ERG-positive/MYC high tumors, is not well understood. Immunohistochemistry (IHC) for ERG and MYC was performed on formalin-fixed, paraffin-embedded tissue from prostate cancer tissue microarrays (TMAs), and nuclear staining was scored semi-quantitatively (IHC product score range = 0-300). Correlation between nuclear ERG and MYC protein expression and association with clinicopathologic parameters and biochemical recurrence after radical prostatectomy was assessed. 29.1% of all tumor nodules showed concurrent nuclear ERG and MYC protein overexpression (i.e., ERG-positive/MYC high), including 35.0% of secondary nodules. Overall, there was weak positive correlation between ERG and MYC expression across all tumor nodules (rpb  = 0.149, P = 0.045), although this correlation was strongest in secondary nodules (rpb  = 0.520, P = 0.019). In radical prostatectomy specimens, ERG-positive/MYC high tumors were positively associated with the presence of extraprostatic extension (EPE), relative to all other ERG/MYC expression subgroups, however, there was no significant association between concurrent nuclear ERG and MYC protein overexpression and time to biochemical recurrence. Concurrent nuclear ERG and MYC protein overexpression is common in prostate cancer and defines a subset of locally advanced tumors. Recent data indicates that BET bromodomain proteins regulate ERG gene fusion and MYC gene expression in prostate cancer, suggesting possible synergistic

Methylation of Werner syndrome protein is associated with the occurrence and development of invasive meningioma via the regulation of Myc and p53 expression.

PubMed

Li, Puxian; Hao, Shuyu; Bi, Zhiyong; Zhang, Junting; Wu, Zhen; Ren, Xiaohui

2015-08-01

The aim of the present study was to investigate the positive rate of Werner syndrome protein (WRN) methylation in meningioma patients, and further assess the association between WRN methylation and the occurrence of meningioma. A total of 56 consecutive meningioma patients and 26 healthy individuals were enrolled in the study. A methylation-specific polymerase chain reaction assay was performed to detect the positive rate of WRN methylation in the peripheral blood and tissue samples collected from the recruited subjects. In addition, western blot analysis was performed to determine the protein expression levels of WRN, Myc and p53 in the peripheral blood and tissue samples. The positive rate of WRN methylation in the peripheral blood of the meningioma group was increased when compared with the control group (P<0.05). In addition, the protein expression levels of WRN were significantly decreased in the peripheral blood and tissue samples collected from the individuals with a positive WRN methylation status (P<0.05), as compared with the samples without WRN methylation. Furthermore, the protein expression levels of Myc and p53 were increased in the peripheral blood and tissue samples that exhibited positive WRN methylation when compared with those without WRN methylation (P<0.05). Therefore, WRN methylation was demonstrated to be associated with the occurrence and development of invasive meningioma, possibly through the regulation of Myc and p53 expression.

Deptor Is a Novel Target of Wnt/β-Catenin/c-Myc and Contributes to Colorectal Cancer Cell Growth.

PubMed

Wang, Qingding; Zhou, Yuning; Rychahou, Piotr; Harris, Jennifer W; Zaytseva, Yekaterina Y; Liu, Jinpeng; Wang, Chi; Weiss, Heidi L; Liu, Chunming; Lee, Eun Y; Evers, B Mark

2018-06-15

Activation of the Wnt/β-catenin signaling pathway drives colorectal cancer growth by deregulating expression of downstream target genes, including the c-myc proto-oncogene. The critical targets that mediate the functions of oncogenic c-Myc in colorectal cancer have yet to be fully elucidated. Previously, we showed that activation of PI3K/Akt/mTOR contributes to colorectal cancer growth and metastasis. Here, we show that Deptor, a suppressor of mTOR, is a direct target of Wnt/β-catenin/c-Myc signaling in colorectal cancer cells. Inhibition of Wnt/β-catenin or knockdown of c-Myc decreased, while activation of Wnt/β-catenin or overexpression of c-Myc increased the expression of Deptor. c-Myc bound the promoter of Deptor and transcriptionally regulated Deptor expression. Inhibition of Wnt/β-catenin/c-Myc signaling increased mTOR activation, and the combination of Wnt and Akt/mTOR inhibitors enhanced inhibition of colorectal cancer cell growth in vitro and in vivo Deptor expression was increased in colorectal cancer cells; knockdown of Deptor induced differentiation, decreased expression of B lymphoma Mo-MLV insertion region 1 (Bmi1), and decreased proliferation in colorectal cancer cell lines and primary human colorectal cancer cells. Importantly, our work identifies Deptor as a downstream target of the Wnt/β-catenin/c-Myc signaling pathway, acting as a tumor promoter in colorectal cancer cells. Moreover, we provide a molecular basis for the synergistic combination of Wnt and mTOR inhibitors in treating colorectal cancer with elevated c-Myc. Significance: The mTOR inhibitor DEPTOR acts as a tumor promoter and could be a potential therapeutic target in colorectal cancer. Cancer Res; 78(12); 3163-75. ©2018 AACR . ©2018 American Association for Cancer Research.

Regulation of c-Myc mRNA by L11 in Response to UV and Gamma irradiation

DTIC Science & Technology

2011-10-01

release of L11 from the nucleolus to the nucleoplasm, where it binds to c-Myc protein, and to the cytoplasm, where it binds to c-myc mRNA. We also found...rRNA and ribosomal proteins (RPs), rRNA processing, and the as- sembly of the mature ribosome subunits in the nucleolus fol- lowed by their transport...from the nucleolus or from intact ribosomes to suppress MDM2 (68). However, whether L11 suppresses c-Myc in response to ribosomal stress is not known

Preoperative chemoradiotherapy for rectal cancer: the sensitizer role of the association between miR-375 and c-Myc

PubMed Central

Conde-Muiño, Raquel; Cano, Carlos; Sánchez-Martín, Victoria; Herrera, Antonio; Comino, Ana; Medina, Pedro P.; Palma, Pablo; Cuadros, Marta

2017-01-01

Administration of chemoradiation before tumor resection has revolutionized the management of locally advanced rectal cancer, but many patients have proven resistant to this preoperative therapy. Our group recently reported a negative correlation between c-Myc gene expression and this resistance. In the present study, integrated analysis of miRNA and mRNA expression profiles was conducted in 45 pre-treatment rectal tumors in order to analyze the expressions of miRNAs and c-Myc and their relationship with clinicopathological factors and patient survival. Twelve miRNAs were found to be differentially expressed by responders and non-responders to the chemoradiation. Functional classification revealed an association between the differentially expressed miRNAs and c-Myc. Quantitative real-time PCR results showed that miRNA-148 and miRNA-375 levels were both significantly lower in responders than in non-responders. Notably, a significant negative correlation was found between miRNA-375 expression and c-Myc expression. According to these findings, miRNA-375 and its targeted c-Myc may be useful as a predictive biomarker of the response to neoadjuvant treatment in patients with locally advanced rectal cancer. PMID:29137264

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

c-MYC independent nuclear reprogramming favors cardiogenic potential of induced pluripotent stem cells

PubMed Central

Martinez-Fernandez, Almudena; Nelson, Timothy J.; Ikeda, Yasuhiro; Terzic, Andre

2010-01-01

Induced pluripotent stem cell (iPS) technology has launched a new platform in regenerative medicine aimed at deriving unlimited replacement tissue from autologous sources through somatic cell reprogramming using stemness factor sets. In this way, authentic cardiomyocytes have been obtained from iPS and recently demonstrated in proof-of-principle studies to repair infarcted heart. Optimizing the cardiogenic potential of iPS progeny would ensure a maximized yield of bioengineered cardiac tissue. Here, we reprogrammed fibroblasts in the presence or absence of c-MYC to determine if the acquired cardiogenicity is sensitive to the method of nuclear reprogramming. Using lentiviral constructs that expressed stemness factors SOX2, OCT4, and KLF4 with or without c-MYC, iPS clones generated through fibroblast reprogramming demonstrated indistinguishable characteristics for 5 days of differentiation with similar cell morphology, growth rates, and chimeric embryo integration. However, 4-factor c-MYC dependent nuclear reprogramming produced iPS progeny that consistently prolonged the expression of pluripotent Oct-4 and Fgf4 genes and repressed cardiac differentiation. In contrast, 3-factor c-MYC-less iPS clones efficiently up-regulated pre-cardiac (CXCR4, Flk-1, and Mesp1/2) and cardiac (Nkx2.5, Mef2c, and Myocardin) gene expression patterns. In fact, 3-factor iPS progeny demonstrated early and robust cardiogenesis during in vitro differentiation with consistent beating activity, sarcomere maturation, and rhythmical intracellular calcium dynamics. Thus, nuclear reprogramming independent of c-MYC enhances production of pluripotent stem cells with innate cardiogenic potential. PMID:20221419

Subchronic exposure of benzo(a)pyrene interferes with the expression of Bcl-2, Ki-67, C-myc and p53, Bax, Caspase-3 in sub-regions of cerebral cortex and hippocampus.

PubMed

He, Jianlong; Ji, Xiaoying; Li, Yongfei; Xue, Xiaochang; Feng, Guodong; Zhang, Huqin; Wang, Huichun; Gao, Meilii

2016-01-01

Benzo[a]pyrene [B(a)P], a representative substance of the polycyclic aromatic hydrocarbons, is an ubiquitous environmental contaminant. However, the mechanism of B(a)P neurotoxicity is still not clear. The aim of this study was to investigate the molecular mechanism by assay the expression of Bcl-2, C-myc, Ki-67 oncogene and p53, Bax, Caspase-3 proapoptotic gene in sub-regions of cerebral cortex and hippocampus in brain. Mice were administrated with subchronic intraperitoneal injection and oral gavage of B(a)P (2.5, 5, 10mg/kg body weight) for 13 weeks. We observed that B(a)P induced the significant increase in relative brain weights and the slight proliferation phenomenon in hippocampus in the experiment. Significant increase of C-myc, Ki-67 and p53, Bax, Caspase-3 and dramatic decrease of Bcl-2 protein levels were observed through immunohistochemical analysis. The relative higher interference of Bcl-2, C-myc, Ki-67 and p53, Bax, Caspase-3 proteins was observed in hippocampus sub-regions of dentate gyrus, cornu ammonis 3 and cornu ammonis 1. The relative lower interference of the examined genes was found in cerebral cortex sub-regions of frontal cortex, temporal cortex and parietal cortex. The results showed a region-difference manner with accompanying dose-dependent manner in brain hippocampus and cerebral cortex induced by B(a)P. These findings indicate that B(a)P-induced subchronic neural toxicity may occur through the enhancement in Bcl-2, C-myc, Ki-67 oncogenes and p53, Bax, Caspase-3 proapoptotic genes expression. Copyright © 2015 Elsevier GmbH. All rights reserved.

Evaluation of the antitumor effects of c-Myc-Max heterodimerization inhibitor 100258-F4 in ovarian cancer cells.

PubMed

Wang, Jiandong; Ma, Xiaoli; Jones, Hannah M; Chan, Leo Li-Ying; Song, Fang; Zhang, Weiyuan; Bae-Jump, Victoria L; Zhou, Chunxiao

2014-08-21

Epithelial ovarian carcinoma is the most lethal gynecological cancer due to its silent onset and recurrence with resistance to chemotherapy. Overexpression of oncogene c-Myc is one of the most frequently encountered events present in ovarian carcinoma. Disrupting the function of c-Myc and its downstream target genes is a promising strategy for cancer therapy. Our objective was to evaluate the potential effects of small-molecule c-Myc inhibitor, 10058-F4, on ovarian carcinoma cells and the underlying mechanisms by which 10058-F4 exerts its actions. Using MTT assay, colony formation, flow cytometry and Annexin V FITC assays, we found that 10058-F4 significantly inhibited cell proliferation of both SKOV3 and Hey ovarian cancer cells in a dose dependent manner through induction of apoptosis and cell cycle G1 arrest. Treatment with 10058-F4 reduced cellular ATP production and ROS levels in SKOV3 and Hey cells. Consistently, primary cultures of ovarian cancer treated with 10058-F4 showed induction of caspase-3 activity and inhibition of cell proliferation in 15 of 18 cases. The response to 10058-F4 was independent the level of c-Myc protein over-expression in primary cultures of ovarian carcinoma. These novel findings suggest that the growth of ovarian cancer cells is dependent upon c-MYC activity and that targeting c-Myc-Max heterodimerization could be a potential therapeutic strategy for ovarian cancer.

Driver or passenger effects of augmented c-Myc and Cdc20 in gliomagenesis.

PubMed

Ji, Ping; Zhou, Xinhui; Liu, Qun; Fuller, Gregory N; Phillips, Lynette M; Zhang, Wei

2016-04-26

Cdc20 and c-Myc are commonly overexpressed in a broad spectrum of cancers, including glioblastoma (GBM). Despite this clear association, whether c-Myc and Cdc20 overexpression is a driver or passenger event in gliomagenesis remains unclear. Both c-Myc and Cdc20 induced the proliferation of primary glial progenitor cells. c-Myc also promoted the formation of soft agar anchorage-independent colonies. In the RCAS/Ntv-a glia-specific transgenic mouse model, c-Myc increased the GBM incidence from 19.1% to 47.4% by 12 weeks of age when combined with kRas and Akt3 in Ntv-a INK4a-ARF (also known as CDKN2A)-null mice. In contrast, Cdc20 decreased the GBM incidence from 19.1% to 9.1%. Moreover, cell differentiation was modulated by c-Myc in kRas/Akt3-induced GBM on the basis of Nestin/GFAP expression (glial progenitor cell differentiation), while Cdc20 had no effect on primary glial progenitor cell differentiation. We used glial progenitor cells from Ntv-a newborn mice to evaluate the role of c-Myc and Cdc20 in the proliferation and transformation of GBM in vitro and in vivo. We further determined whether c-Myc and Cdc20 have a driver or passenger role in GBM development using kRas/Akt3 signals in a RCAS/Ntv-a mouse model. These results suggest that the driver or passenger of oncogene signaling is dependent on cellular status. c-Myc is a driver when combined with kRas/Akt3 oncogenic signals in gliomagenesis, whereas Cdc20 overexpression is a passenger. Inhibition of cell differentiation of c-Myc may be a target for anti-glioma therapy.

MYC association with cancer risk and a new model of MYC-mediated repression.

PubMed

Cole, Michael D

2014-07-01

MYC is one of the most frequently mutated and overexpressed genes in human cancer but the regulation of MYC expression and the ability of MYC protein to repress cellular genes (including itself) have remained mysterious. Recent genome-wide association studies show that many genetic polymorphisms associated with disease risk map to distal regulatory elements that regulate the MYC promoter through large chromatin loops. Cancer risk-associated single-nucleotide polymorphisms (SNPs) contain more potent enhancer activity, promoting higher MYC levels and a greater risk of disease. The MYC promoter is also subject to complex regulatory circuits and limits its own expression by a feedback loop. A model for MYC autoregulation is discussed which involves a signaling pathway between the PTEN (phosphatase and tensin homolog) tumor suppressor and repressive histone modifications laid down by the EZH2 methyltransferase. Copyright © 2014 Cold Spring Harbor Laboratory Press; all rights reserved.

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

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Harnicarova, Andrea; Kozubek, Stanislav; Pachernik, Jiri

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 andmore » 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.« less

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

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Guo, Pin; Nie, Quanmin; Lan, Jin

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

Both core and F proteins of hepatitis C virus could enhance cell proliferation in transgenic mice

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hu, Wen-Ta; Li, Hui-Chun; Lee, Shen-Kao

Highlights: •HCV core and F proteins could induce hepatocyte proliferation in the transgenic mice. •β-Catenin signaling pathway was activated by core protein in the transgenic mice. •β-Catenin signaling pathway was activated by myc-F protein in the transgenic mice. •Expression of SMA protein was enhanced by core but not myc-F protein. -- Abstract: The role of the protein encoded by the alternative open reading frame (ARF/F/core+1) of the Hepatitis C virus (HCV) genome in viral pathogenesis remains unknown. The different forms of ARF/F/core+1 protein were labile in cultured cells, a myc-tag fused at the N-terminus of the F protein made itmore » more stable. To determine the role of core and F proteins in HCV pathogenesis, transgenic mice with either protein expression under the control of Albumin promoter were generated. Expression of core protein and F protein with myc tag (myc-F) could be detected by Western blotting analysis in the livers of these mice. The ratio of liver to body weight is increased for both core and myc-F transgenic mice compared to that of wild type mice. Indeed, the proliferating cell nuclear antigen protein, a proliferation marker, was up-regulated in the transgenic mice with core or myc-F protein. Further analyses by microarray and Western blotting suggested that β-catenin signaling pathway was activated by either core or myc-F protein in the transgenic mice. These transgenic mice were further treated with either Diethynitrosamine (a tumor initiator) or Phenobarbital (a tumor promoter). Phenobarbital but not Diethynitrosamine treatment could increase the liver/body weight ratio of these mice. However, no tumor formation was observed in these mice. In conclusion, HCV core and myc-F proteins could induce hepatocyte proliferation in the transgenic mice possibly through β-catenin signaling pathway.« less

Expression of c-myc and c-fos and binding sites for estradiol and progesterone in human pituitary tumors.

PubMed

Machiavelli, G A; Rivolta, C M; Artese, R; Basso, A; Burdman, J A

1998-12-01

We studied the concentration of mRNA from the oncogenes c-myc and c-fos in human pituitary adenomas by Northern blot hybridization (35 somatotrophinomas, 9 prolactinomas, 21 nonsecreting and 3 adrenocorticotrophinomas). The concentration of estrogens and progesterone receptors was also investigated. The levels of c-myc and c-fos mRNA was higher in nonsecreting tumors which were generally the largest and had a higher percentage of recurrence after surgery than the other groups. High concentration of estrogen receptors was observed in tumors derived from cells which are normally the target of this hormone, mainly prolactinomas. They were also present in somatotrophic and nonsecreting adenomas, related to the presence of prolactin or gonadotrophin cells in these tumors. The presence of estrogen receptors indicates that the tumor cells maintain their differentiation and a good prognosis as is the case for prolactinomas. We did not find any relationship between estrogen receptors and the concentration of c-myc and c-fos oncogenes. Larger adenomas (mainly nonsecreting) had higher levels of c-myc and c-fos mRNA than the other tumors and they had an important percentage of recurrence after surgery. It is clear that tumor size is related to the outcome after surgery and that nonsecreting adenomas are usually large because of the late diagnosis. However two large somatotrophinomas with extrasellar expansion also had overexpression of both oncogenes and both relapsed after surgery.

Pre-clinical analysis of changes in intra-cellular biochemistry of glioblastoma multiforme (GBM) cells due to c-Myc silencing.

PubMed

Rajagopalan, Vishal; Vaidyanathan, Muthukumar; Janardhanam, Vanisree Arambakkam; Bradner, James E

2014-10-01

Glioblastoma Multiforme (GBM) is an aggressive form of brain Tumor that has few cures. In this study, we analyze the anti-proliferative effects of a new molecule JQ1 against GBMs induced in Wistar Rats. JQ1 is essentially a Myc inhibitor. c-Myc is also known for altering the biochemistry of a tumor cell. Therefore, the study is intended to analyze certain other oncogenes associated with c-Myc and also the change in cellular biochemistry upon c-Myc inhibition. The quantitative analysis of gene expression gave a co-expressive pattern for all the three genes involved namely; c-Myc, Bcl-2, and Akt. The cellular biochemistry analysis by transmission electron microscopy revealed high glycogen and lipid aggregation in Myc inhibited cells and excessive autophagy. The study demonstrates the role of c-Myc as a central metabolic regulator and Bcl-2 and Akt assisting in extending c-Myc half-life as well as in regulation of autophagy, so as to regulate cell survival on the whole. The study also demonstrates that transient treatment by JQ1 leads to aggressive development of tumor and therefore, accelerating death, emphasizing the importance of dosage fixation, and duration for clinical use in future.

Downregulation of N‑Myc inhibits neuroblastoma cell growth via the Wnt/β‑catenin signaling pathway.

PubMed

Wang, Yingge; Gao, Shan; Wang, Weiguang; Xia, Yuting; Liang, Jingyan

2018-05-03

Neuroblastoma, one of the most common types of cancer in childhood, is commonly treated with surgery, radiation and chemotherapy. However, prognosis and survival remain poor for children with high‑risk neuroblastoma. Therefore, the identification of novel, effective therapeutic targets is necessary. N‑Myc, a proto‑oncogene protein encoded by the v‑myc avial myelocytomatosis viral oncogene neuroblastoma derived homolog (MYCN) gene, is associated with tumorigenesis. In the present study, the effect of N‑Myc silencing on MYCN‑amplified CHP134 and BE‑2C neuroblastoma cells was evaluated, and the underlying molecular mechanism was investigated. N‑Myc was successfully knocked down using an N‑Myc‑specific small interfering RNA, the efficacy of interference efficiency confirmed by reverse transcription‑quantitative polymerase chain reaction and western blotting. Cell viability was evaluated by MTT assay and apoptosis was measured by ELISA assay. The results indicated that MYCN silencing significantly decreased cell viability and promoted apoptosis. Subsequently, the expression levels of key Wnt/β‑catenin signaling pathway proteins were detected by western blotting, and MYCN silencing was demonstrated to inhibit Wnt/β‑catenin signaling, decreasing the expression ofanti‑apoptosis proteins and increasing the expression of pro‑apoptosis protein. This suggested that N‑Myc regulated survival and growth of CHP134 and BE‑2C neuroblastoma cells, potentially through Wnt/β‑catenin signaling. Furthermore, associated proteins, N‑Myc and STAT interactor and dickkopf Wnt signaling pathway inhibitor 1, were demonstrated to be involved in this regulation. Therefore, N‑Myc and its downstream targets may provide novel therapeutic targets for the treatment of neuroblastoma.

Focal Adhesion Kinase Is Required for Intestinal Regeneration and Tumorigenesis Downstream of Wnt/c-Myc Signaling

PubMed Central

Ashton, Gabrielle H.; Morton, Jennifer P.; Myant, Kevin; Phesse, Toby J.; Ridgway, Rachel A.; Marsh, Victoria; Wilkins, Julie A.; Athineos, Dimitris; Muncan, Vanesa; Kemp, Richard; Neufeld, Kristi; Clevers, Hans; Brunton, Valerie; Winton, Douglas J.; Wang, Xiaoyan; Sears, Rosalie C.; Clarke, Alan R.; Frame, Margaret C.; Sansom, Owen J.

2012-01-01

SUMMARY The intestinal epithelium has a remarkable capacity to regenerate after injury and DNA damage. Here, we show that the integrin effector protein Focal Adhesion Kinase (FAK) is dispensable for normal intestinal homeostasis and DNA damage signaling, but is essential for intestinal regeneration following DNA damage. Given Wnt/c-Myc signaling is activated following intestinal regeneration, we investigated the functional importance of FAK following deletion of the Apc tumor suppressor protein within the intestinal epithelium. Following Apc loss, FAK expression increased in a c-Myc-dependent manner. Codeletion of Apc and Fak strongly reduced proliferation normally induced following Apc loss, and this was associated with reduced levels of phospho-Akt and suppression of intestinal tumorigenesis in Apc heterozygous mice. Thus, FAK is required downstream of Wnt Signaling, for Akt/mTOR activation, intestinal regeneration, and tumorigenesis. Importantly, this work suggests that FAK inhibitors may suppress tumorigenesis in patients at high risk of developing colorectal cancer. PMID:20708588

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

PubMed

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

2014-06-01

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

Conserved features of cancer cells define their sensitivity of HAMLET-induced death; c-Myc and glycolysis

PubMed Central

Storm, Petter; Puthia, Manoj Kumar; Aits, Sonja; Urbano, Alexander; Northen, Trent; Powers, Scott; Bowen, Ben; Chao, Yinxia; Reindl, Wolfgang; Lee, Do Yup; Sullivan, Nancy Liu; Zhang, Jianping; Trulsson, Maria; Yang, Henry; Watson, James; Svanborg, Catharina

2014-01-01

HAMLET is the first member of a new family of tumoricidal protein-lipid complexes that kill cancer cells broadly, while sparing healthy, differentiated cells. Many and diverse tumor cell types are sensitive to the lethal effect, suggesting that HAMLET identifies and activates conserved death pathways in cancer cells. Here we investigated the molecular basis for the difference in sensitivity between cancer cells and healthy cells. Using a combination of small hairpin RNA inhibition, proteomic and metabolomic technology we identified the c-Myc oncogene as one essential determinant of HAMLET sensitivity. Increased c-Myc expression levels promoted the sensitivity to HAMLET and shRNA knockdown of c-Myc suppressed the lethal response, suggesting that oncogenic transformation with c-Myc creates a HAMLET-sensitive phenotype. Furthermore, the HAMLET sensitivity was modified by the glycolytic state of the tumor cells. Glucose deprivation sensitized tumor cells to HAMLET-induced cell death and in the shRNA screen Hexokinase 1, PFKFB1 and HIF1α modified HAMLET sensitivity. Hexokinase 1 was shown to bind HAMLET in a protein array containing approximately 8000 targets and Hexokinase activity decreased within 15 minutes of HAMLET treatment, prior to morphological signs of tumor cell death. In parallel, HAMLET triggered rapid metabolic paralysis in carcinoma cells. The glycolytic machinery was modified and glycolysis was shifted towards the pentose phosphate pathway. Tumor cells were also shown to contain large amounts of oleic acid and its derivatives already after 15 minutes. The results identify HAMLET as a novel anti-cancer agent that kills tumor cells by exploiting unifying features of cancer cells such as oncogene-addiction or the Warburg effect. PMID:21643007

Conserved features of cancer cells define their sensitivity to HAMLET-induced death; c-Myc and glycolysis.

PubMed

Storm, P; Aits, S; Puthia, M K; Urbano, A; Northen, T; Powers, S; Bowen, B; Chao, Y; Reindl, W; Lee, D Y; Sullivan, N L; Zhang, J; Trulsson, M; Yang, H; Watson, J D; Svanborg, C

2011-12-01

HAMLET is the first member of a new family of tumoricidal protein-lipid complexes that kill cancer cells broadly, while sparing healthy, differentiated cells. Many and diverse tumor cell types are sensitive to the lethal effect, suggesting that HAMLET identifies and activates conserved death pathways in cancer cells. Here, we investigated the molecular basis for the difference in sensitivity between cancer cells and healthy cells. Using a combination of small-hairpin RNA (shRNA) inhibition, proteomic and metabolomic technology, we identified the c-Myc oncogene as one essential determinant of HAMLET sensitivity. Increased c-Myc expression levels promoted sensitivity to HAMLET and shRNA knockdown of c-Myc suppressed the lethal response, suggesting that oncogenic transformation with c-Myc creates a HAMLET-sensitive phenotype. Furthermore, HAMLET sensitivity was modified by the glycolytic state of tumor cells. Glucose deprivation sensitized tumor cells to HAMLET-induced cell death and in the shRNA screen, hexokinase 1 (HK1), 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase 1 and hypoxia-inducible factor 1α modified HAMLET sensitivity. HK1 was shown to bind HAMLET in a protein array containing ∼8000 targets, and HK activity decreased within 15 min of HAMLET treatment, before morphological signs of tumor cell death. In parallel, HAMLET triggered rapid metabolic paralysis in carcinoma cells. Tumor cells were also shown to contain large amounts of oleic acid and its derivatives already after 15 min. The results identify HAMLET as a novel anti-cancer agent that kills tumor cells by exploiting unifying features of cancer cells such as oncogene addiction or the Warburg effect.

Enforced expression of the c-myc oncogene inhibits cell differentiation by precluding entry into a distinct predifferentiation state in G/sub 0//G/sub 1/

DOE Office of Scientific and Technical Information (OSTI.GOV)

Freytag, S.O.

1988-04-01

A broad base of data has implicated a role for the c-myc proto-oncogene in the control of the cell cycle and cell differentiation. To further define the role of myc in these processes, the authors examined the effect of enforced myc expression on several events that are thought to be important steps leading to the terminally differentiated state: (i) the ability to arrest growth in G/sub 0//G/sub 1/, (ii) the ability to replicate the genome upon initiation of the differentiation program, and (iii) the ability to loose responsiveness to mitogens and withdraw from the cell cycle. 3T3-L1 preadipocyte cell linesmore » expressing various levels of myc mRNA were established by transfection with a recombinant myc gene under the transcriptional control of the Rous sarcoma virus (RSV) promoter. Cells that expressed high constitutive levels of pRSV myc mRNA arrested in G/sub 0//G/sub 1/ at densities similar to those of normal cells at confluence. Upon initiation of the differentiation program, such cells traversed the cell cycle with kinetics similar to those of normal cells and subsequently arrested in G/sub 0//G/sub 1/. Thus, enforced expression of myc had no effect on the ability of cells to arrest growth in G/sub 0//G/sub 1/ or to replicate the genome upon initiation of the differentiation program. Cells were then tested for their ability to reenter the cell cycle upon exposure to high concentrations of serum and for their capacity to differentiate. In contrast to normal cells, cells expressing high constitutive levels of myc RNA reentered the cell cycle when challenged with 30% serum and failed to terminally differentiate.« less

AKT1, LKB1, and YAP1 revealed as MYC interactors with NanoLuc-based protein-fragment complementation assay. | Office of Cancer Genomics

Cancer.gov

The c-Myc (MYC) transcription factor is a major cancer driver and a well-validated therapeutic target. However, directly targeting MYC has been challenging. Thus, identifying proteins that interact with and regulate MYC may provide alternative strategies to inhibit its oncogenic activity. Here we report the development of a NanoLuc®-based protein-fragment complementation assay (NanoPCA) and mapping of the MYC protein interaction hub in live mammalian cells.

Cis activation of the c-myc gene in bovine papilloma virus type 1/human c-myc hybrid plasmids

DOE Office of Scientific and Technical Information (OSTI.GOV)

Modjtahedi, N.; Feunteun, J.; Brison, O.

1988-01-01

The c-myc gene amplification observed in human tumors is likely to represent an activation mechanism aiming at an increased transcription level. In order to evaluate the biological significance of this amplification in the malignant transformation the authors designed an experimental model that could possibly mimic this situation in vitro. They have constructed a series of plasmids which physically link the human c-myc gene to the bovine papilloma virus type 1 genome (BPV1) and therefore should be maintained as amplified episomes upon transformation of rodent cells. Anticipating that the high copy number will bring about the immortalizing capacity of the c-mycmore » gene, the constructions were introduced into primary rat embryo cells. Immortal cell lines were established by transfection of the hybrid plasmids carrying either the complete BPV1 genome or the transforming region of the viral genome. The BPV1 DNA alone or the c-myc gene alone has no activity in this assay. The analysis of the established cell lines demonstrates that the transfected plasmids are present not as free copies as anticipated but rather integrated as tandem repeats. They present data which strongly suggest that the immortalization capacity of the hybrid plasmids reflects the activation of the c-myc gene by the transactivable BPV1 enhancer. Although both the BPV1 early genes and the c-myc gene are actively transcribed, most of the cell lines do not display a transformed phenotype.« less

Anti-apoptotic A1 is not essential for lymphoma development in Eµ-Myc mice but helps sustain transplanted Eµ-Myc tumour cells.

PubMed

Mensink, Mark; Anstee, Natasha S; Robati, Mikara; Schenk, Robyn L; Herold, Marco J; Cory, Suzanne; Vandenberg, Cassandra J

2018-03-01

The transcription factor c-MYC regulates a multiplicity of genes involved in cellular growth, proliferation, metabolism and DNA damage response and its overexpression is a hallmark of many tumours. Since MYC promotes apoptosis under conditions of stress, such as limited availability of nutrients or cytokines, MYC-driven cells are very much dependent on signals that inhibit cell death. Stress signals trigger apoptosis via the pathway regulated by opposing fractions of the BCL-2 protein family and previous genetic studies have shown that the development of B lymphoid tumours in Eµ-Myc mice is critically dependent on expression of pro-survival BCL-2 relatives MCL-1, BCL-W and, to a lesser extent, BCL-X L , but not BCL-2 itself, and that sustained growth of these lymphomas is dependent on MCL-1. Using recently developed mice that lack expression of all three functional pro-survival A1 genes, we show here that the kinetics of lymphoma development in Eµ-Myc mice and the competitive repopulation capacity of Eµ-Myc haemopoietic stem and progenitor cells is unaffected by the absence of A1. However, conditional loss of a single remaining functional A1 gene from transplanted A1-a -/- A1-b fl/fl A1-c -/- Eµ-Myc lymphomas slowed their expansion, significantly extending the life of the transplant recipients. Thus, A1 contributes to the survival of malignant Eµ-Myc-driven B lymphoid cells. These results strengthen the case for BFL-1, the human homologue of A1, being a valid target for drug development for MYC-driven tumours.

Androgen Receptor (AR) Suppresses Normal Human Prostate Epithelial Cell Proliferation via AR/β-catenin/TCF-4 Complex Inhibition of c-MYC Transcription

PubMed Central

Antony, Lizamma; van der Schoor, Freek; Dalrymple, Susan L.; Isaacs, John T.

2016-01-01

INTRODUCTION Physiologic testosterone continuously stimulates prostate stromal cell secretion of paracrine growth factors (PGFs), which if unopposed would induce hyperplastic overgrowth of normal prostate epithelial cells (PrECs). METHODS Lentiviral shRNA stable knock down of c-MYC, β-catenin, or TCF-4 completely inhibits normal (i.e., non-transformed) human PrECs growth. c-MYC enhancer driven reporter expression and growth is inhibited by two chemically distinct molecules, which prevent β-catenin signaling either by blocking TCF-4 binding (i.e., toxoflavin) or by stimulating degradation (i.e., AVX939). Recombinant DKK1 protein at a dose, which inhibits activation of canonical Wnt signaling does not inhibit PrEC growth. Nuclear β-catenin translocation and PrEC growth is prevented by both lack of PGFs or Akt inhibitor-I. Growth inhibition induced by lack of PGFs, toxoflavin, or Akt inhibitor-I is overcome by constitutive c-MYC transcription. RESULTS In the presence of continuous PGF signaling, PrEC hyperplasia is prevented by androgen binding to AR suppressing c-MYC transcription, resulting in G0 arrest/terminal differentiation independent of Rb, p21, p27, FoxP3, or down regulation of growth factors receptors and instead involves androgen-induced formation of AR/β-catenin/TCF-4 complexes, which suppress c-MYC transcription. Such suppression does not occur when AR is mutated in its zinc-finger binding domain. DISCUSSION Proliferation of non-transformed human PrECs is dependent upon c-MYC transcription via formation/binding of β-catenin/TCF-4 complexes at both 5′ and 3′ c-MYC enhancers stimulated by Wnt-independent, PGF induced Akt signaling. In the presence of continuous PGF signaling, PrEC hyperplasia is prevented by androgen-induced formation of AR/β-catenin/TCF-4 complexes, which retains binding to 3′ c-MYC enhancer, but now suppresses c-MYC transcription. PMID:24913829

DNA Methylation Mediated Downregulation of miR-449c Controls Osteosarcoma Cell Cycle Progression by Directly Targeting Oncogene c-Myc

PubMed Central

Li, Qing; Li, Hua; Zhao, Xueling; Wang, Bing; Zhang, Lin; Zhang, Caiguo; Zhang, Fan

2017-01-01

MicroRNAs (miRNAs) are critical regulators of gene expression, and they have broad roles in the pathogenesis of different diseases including cancer. Limited studies and expression profiles of miRNAs are available in human osteosarcoma cells. By applying a miRNA microarray analysis, we observed a number of miRNAs with abnormal expression in cancerous tissues from osteosarcoma patients. Of particular interest in this study was miR-449c, which was significantly downregulated in osteosarcoma cells and patients, and its expression was negatively correlated with tumor size and tumor MSTS stages. Ectopic expression of miR-449c significantly inhibited osteosarcoma cell proliferation and colony formation ability, and caused cell cycle arrest at the G1 phase. Further analysis identified that miR-449c was able to directly target the oncogene c-Myc and negatively regulated its expression. Overexpression of c-Myc partially reversed miR-449c-mimic-inhibited cell proliferation and colony formation. Moreover, DNA hypermethylation was observed in two CpG islands adjacent to the genomic locus of miR-449c in osteosarcoma cells. Conversely, treatment with the DNA methylation inhibitor AZA caused induction of miR-449c. In conclusion, our results support a model that DNA methylation mediates downregulation of miR-449c, diminishing miR-449c mediated inhibition of c-Myc and thus leading to the activation of downstream targets, eventually contributing to osteosarcoma tumorigenesis. PMID:28924385

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

PubMed

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

2016-03-01

Epidemiological studies have demonstrated that cigarette smoking is an important cofactor or an independent risk factor for the development of cervical cancer. Benzo(a)pyrene (BaP) is one of the most potent tobacco smoke carcinogens in tobacco smoke. BaP induced DNA damage and over expression in p53 cervical tissue of mice as demonstrated in our previous study. Here we present the findings of exposure to BaP on the expression of Bcl-2, C-myc, Ki-67, Caspase-3 and Bax genes in mouse cervix. Acute intraperitoneal administration of BaP (12.5, 25, 50, 100mg/kg body weight) to ICR female mice induced a significant increase in Bcl-2, C-myc, Ki-67 mRNA and protein level till 72h except in Bcl-2 at 24h with 12.5, 25, 50mg/kg as well as at 48h with 12.5mg/kg body weight post treatment. A significant increase was also seen in Caspase-3 and Bax mRNA and protein level with peak level at 24h and gradual decrease till 72h, however, the expression of caspase-3 increased while that of Bax decreased with increasing dose of Bap after 24h. In sub chronic intraperitoneal and oral gavage administration of BaP (2.5, 5, 10mg/kg body weight), similar significant increase was observed for all the examined genes as compared to the control and vehicle groups, however the expression of Bax decreased in a dose dependent manner. The findings of this study will help in further understanding the molecular mechanism of BaP induced carcinogenesis of cervical cancer. Copyright © 2015 Elsevier GmbH. All rights reserved.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Olson, Aaron; Ledee, Dolena; Iwamoto, Kate

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,more » 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

Suppression of c-Myc is involved in multi-walled carbon nanotubes' down-regulation of ATP-binding cassette transporters in human colon adenocarcinoma cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Zhaojing; Xu, Yonghong; Meng, Xiangning

Over-expression of ATP-binding cassette (ABC) transporters, a large family of integral membrane proteins that decrease cellular drug uptake and accumulation by active extrusion, is one of the major causes of cancer multi-drug resistance (MDR) that frequently leads to failure of chemotherapy. Carbon nanotubes (CNTs)-based drug delivery devices hold great promise in enhancing the efficacy of cancer chemotherapy. However, CNTs' effects on the ABC transporters remain under-investigated. In this study, we found that multiwalled carbon nanotubes (MWCNTs) reduced transport activity and expression of ABC transporters including ABCB1/Pgp and ABCC4/MRP4 in human colon adenocarcinoma Caco-2 cells. Proto-oncogene c-Myc, which directly regulates ABCmore » gene expression, was concurrently decreased in MWCNT-treated cells and forced over-expression of c-Myc reversed MWCNTs' inhibitory effects on ABCB1 and ABCC4 expression. MWCNT-cell membrane interaction and cell membrane oxidative damage were observed. However, antioxidants such as vitamin C, β-mecaptoethanol and dimethylthiourea failed to antagonize MWCNTs' down-regulation of ABC transporters. These data suggest that MWCNTs may act on c-Myc, but not through oxidative stress, to down-regulate ABC transporter expression. Our findings thus shed light on CNTs' novel cellular effects that may be utilized to develop CNTs-based drug delivery devices to overcome ABC transporter-mediated cancer chemoresistance.« less

A Nucleus-Imaging Probe That Selectively Stabilizes a Minor Conformation of c-MYC G-quadruplex and Down-regulates c-MYC Transcription in Human Cancer Cells

PubMed Central

Panda, Deepanjan; Debnath, Manish; Mandal, Samir; Bessi, Irene; Schwalbe, Harald; Dash, Jyotirmayee

2015-01-01

The c-MYC proto-oncogene is a regulator of fundamental cellular processes such as cell cycle progression and apoptosis. The development of novel c-MYC inhibitors that can act by targeting the c-MYC DNA G-quadruplex at the level of transcription would provide potential insight into structure-based design of small molecules and lead to a promising arena for cancer therapy. Herein we report our finding that two simple bis-triazolylcarbazole derivatives can inhibit c-MYC transcription, possibly by stabilizing the c-MYC G-quadruplex. These compounds are prepared using a facile and modular approach based on Cu(I) catalysed azide and alkyne cycloaddition. A carbazole ligand with carboxamide side chains is found to be microenvironment-sensitive and highly selective for “turn-on” detection of c-MYC quadruplex over duplex DNA. This fluorescent probe is applicable to visualize the cellular nucleus in living cells. Interestingly, the ligand binds to c-MYC in an asymmetric fashion and selects the minor-populated conformer via conformational selection. PMID:26286633

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

PubMed

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

2016-07-07

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

A novel form of the RelA nuclear factor kappaB subunit is induced by and forms a complex with the proto-oncogene c-Myc.

PubMed Central

Chapman, Neil R; Webster, Gill A; Gillespie, Peter J; Wilson, Brian J; Crouch, Dorothy H; Perkins, Neil D

2002-01-01

Members of both Myc and nuclear factor kappaB (NF-kappaB) families of transcription factors are found overexpressed or inappropriately activated in many forms of human cancer. Furthermore, NF-kappaB can induce c-Myc gene expression, suggesting that the activities of these factors are functionally linked. We have discovered that both c-Myc and v-Myc can induce a previously undescribed, truncated form of the RelA(p65) NF-kappaB subunit, RelA(p37). RelA(p37) encodes the N-terminal DNA binding and dimerization domain of RelA(p65) and would be expected to function as a trans-dominant negative inhibitor of NF-kappaB. Surprisingly, we found that RelA(p37) no longer binds to kappaB elements. This result is explained, however, by the observation that RelA(p37), but not RelA(p65), forms a high-molecular-mass complex with c-Myc. These results demonstrate a previously unknown functional and physical interaction between RelA and c-Myc with many significant implications for our understanding of the role that both proteins play in the molecular events underlying tumourigenesis. PMID:12027803

Clinical Significance of "Double-hit" and "Double-protein" expression in Primary Gastric B-cell Lymphomas.

PubMed

He, Miaoxia; Chen, Keting; Li, Suhong; Zhang, Shimin; Zheng, Jianming; Hu, Xiaoxia; Gao, Lei; Chen, Jie; Song, Xianmin; Zhang, Weiping; Wang, Jianmin; Yang, Jianmin

2016-01-01

Primary gastric B-cell lymphoma is the second most common malignancy of the stomach. There are many controversial issues about its diagnosis, treatment and clinical management. "Double-hit" and "double-protein" involving gene rearrangement and protein expression of c-Myc and bcl2/bcl6 are the most used terms to describe DLBCL poor prognostic factors in recent years. However, very little is known about the role of these prognostic factors in primary gastric B-cell lymphomas. This study aims to obtain a molecular pathology prognostic model of gastric B-cell lymphoma for clinical stratified management by evaluating how the "double-hit" and "double-protein" in tumor cells as well as microenvironmental reaction of tumor stromal tissue affect clinical outcome in primary gastric B-cell lymphomas. Data and tissues of 188 cases diagnosed with gastric B-cell lymphomas were used in this study. Tumor tissue microarray (TMA) of formalin fixed and paraffin embedded (FFPE) tissues was constructed for fluorescence in situ hybridization (FISH) and immunohistochemistry (IHC) analysis with a serial of biomarkers containing MYC, BCL2, BCL6, CD31, SPARC, CD10, MUM1 and Ki-67. Modeled period analysis was used to estimate 3-year and 5-year overall survival (OS) and disease-free survival (DFS) distributions. There was no definite "double-hit" case though the gene rearrangement of c-Myc (5.9%), bcl2 (0.1%) and bcl6 (7.4%) was found in gastric B-cell lymphomas. The gene amplification or copy gains of c-Myc (10.1%), bcl-2 (17.0%) and bcl-6 (0.9%) were present in these lymphomas. There were 12 cases of the lymphomas with the "double-protein" expression of MYC and BCL2/BCL6. All patients with "double-protein" gastric B-cell lymphomas had poor outcome compared with those without. More importantly, "MYC-BCL2-BCL6" negative group of gastric B-cell lymphoma patients had favorable clinical outcome regardless clinical stage, pathological types and therapeutic modalities. And the similar better

New MYC IHC Classifier Integrating Quantitative Architecture Parameters to Predict MYC Gene Translocation in Diffuse Large B-Cell Lymphoma

PubMed Central

Dong, Wei-Feng; Canil, Sarah; Lai, Raymond; Morel, Didier; Swanson, Paul E.; Izevbaye, Iyare

2018-01-01

A new automated MYC IHC classifier based on bivariate logistic regression is presented. The predictor relies on image analysis developed with the open-source ImageJ platform. From a histologic section immunostained for MYC protein, 2 dimensionless quantitative variables are extracted: (a) relative distance between nuclei positive for MYC IHC based on euclidean minimum spanning tree graph and (b) coefficient of variation of the MYC IHC stain intensity among MYC IHC-positive nuclei. Distance between positive nuclei is suggested to inversely correlate MYC gene rearrangement status, whereas coefficient of variation is suggested to inversely correlate physiological regulation of MYC protein expression. The bivariate classifier was compared with 2 other MYC IHC classifiers (based on percentage of MYC IHC positive nuclei), all tested on 113 lymphomas including mostly diffuse large B-cell lymphomas with known MYC fluorescent in situ hybridization (FISH) status. The bivariate classifier strongly outperformed the “percentage of MYC IHC-positive nuclei” methods to predict MYC+ FISH status with 100% sensitivity (95% confidence interval, 94-100) associated with 80% specificity. The test is rapidly performed and might at a minimum provide primary IHC screening for MYC gene rearrangement status in diffuse large B-cell lymphomas. Furthermore, as this bivariate classifier actually predicts “permanent overexpressed MYC protein status,” it might identify nontranslocation-related chromosomal anomalies missed by FISH. PMID:27093450

Competition between RNA-binding proteins CELF1 and HuR modulates MYC translation and intestinal epithelium renewal

PubMed Central

Liu, Lan; Ouyang, Miao; Rao, Jaladanki N.; Zou, Tongtong; Xiao, Lan; Chung, Hee Kyoung; Wu, Jing; Donahue, James M.; Gorospe, Myriam; Wang, Jian-Ying

2015-01-01

The mammalian intestinal epithelium is one of the most rapidly self-renewing tissues in the body, and its integrity is preserved through strict regulation. The RNA-binding protein (RBP) ELAV-like family member 1 (CELF1), also referred to as CUG-binding protein 1 (CUGBP1), regulates the stability and translation of target mRNAs and is implicated in many aspects of cellular physiology. We show that CELF1 competes with the RBP HuR to modulate MYC translation and regulates intestinal epithelial homeostasis. Growth inhibition of the small intestinal mucosa by fasting in mice was associated with increased CELF1/Myc mRNA association and decreased MYC expression. At the molecular level, CELF1 was found to bind the 3′-untranslated region (UTR) of Myc mRNA and repressed MYC translation without affecting total Myc mRNA levels. HuR interacted with the same Myc 3′-UTR element, and increasing the levels of HuR decreased CELF1 binding to Myc mRNA. In contrast, increasing the concentrations of CELF1 inhibited formation of the [HuR/Myc mRNA] complex. Depletion of cellular polyamines also increased CELF1 and enhanced CELF1 association with Myc mRNA, thus suppressing MYC translation. Moreover, ectopic CELF1 overexpression caused G1-phase growth arrest, whereas CELF1 silencing promoted cell proliferation. These results indicate that CELF1 represses MYC translation by decreasing Myc mRNA association with HuR and provide new insight into the molecular functions of RBPs in the regulation of intestinal mucosal growth. PMID:25808495

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.

Tumor-associated macrophages promote neuroblastoma via STAT3 phosphorylation and up-regulation of c-MYC

PubMed Central

Hadjidaniel, Michael D.; Muthugounder, Sakunthala; Hung, Long T.; Sheard, Michael A.; Shirinbak, Soheila; Chan, Randall Y.; Nakata, Rie; Borriello, Lucia; Malvar, Jemily; Kennedy, Rebekah J.; Iwakura, Hiroshi; Akamizu, Takashi; Sposto, Richard; Shimada, Hiroyuki; DeClerck, Yves A.; Asgharzadeh, Shahab

2017-01-01

Tumor-associated macrophages (TAMs) are strongly associated with poor survival in neuroblastomas that lack MYCN amplification. To study TAM action in neuroblastomas, we used a novel murine model of spontaneous neuroblastoma lacking MYCN amplification, and observed recruitment and polarization of TAMs, which in turn enhanced neuroblastoma proliferation and growth. In both murine and human neuroblastoma cells, we found that TAMs increased STAT3 activation in neuroblastoma cells and transcriptionally up-regulated the MYC oncogene. Analysis of human neuroblastoma tumor specimens revealed that MYC up-regulation correlates with markers of TAM infiltration. In an IL6ko neuroblastoma model, the absence of IL-6 protein had no effect on tumor development and prevented neither STAT3 activation nor MYC up-regulation. In contrast, inhibition of JAK-STAT activation using AZD1480 or the clinically admissible inhibitor ruxolitinib significantly reduced TAM-mediated growth of neuroblastomas implanted subcutaneously in NOD scid gamma mice. Our results point to a unique mechanism in which TAMs promote tumor cells that lack amplification of an oncogene common to the malignancy by up-regulating transcriptional expression of a distinct oncogene from the same gene family, and underscore the role of IL-6-independent activation of STAT3 in this mechanism. Amplification of MYCN or constitutive up-regulation of MYC protein is observed in approximately half of high-risk tumors; our findings indicate a novel role of TAMs as inducers of MYC expression in neuroblastomas lacking independent oncogene activation. PMID:29207662

Acute Myeloid Leukemia with MYC Rearrangement and JAK2 V617F Mutation

PubMed Central

Ohanian, Maro; Bueso-Ramos, Carlos; Ok, Chi Young; Lin, Pei; Patel, Keyur; Alattar, Mona Lisa; Khoury, Joseph D.; Rozovski, Uri; Estrov, Zeev; Huh, Yang O.; Cortes, Jorge; Abruzzo, Lynne V.

2016-01-01

Little is known about MYC dysregulation in myeloid malignancies, and we can find no published studies that have evaluated MYC protein expression in primary cases of myelodysplastic syndromes (MDS) or acute myeloid leukemias (AML). We describe the clinical, morphologic, immunophenotypic, cytogenetic, and molecular genetic findings in two MDS/AML cases that contained both MYC rearrangement and JAK2-V617F mutation. We demonstrate MYC protein expression by immunohistochemistry in both patients. PMID:26382622

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

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.

N-MYC down-regulated-like proteins regulate meristem initiation by modulating auxin transport and MAX2 expression.

PubMed

Mudgil, Yashwanti; Ghawana, Sanjay; Jones, Alan M

2013-01-01

N-MYC down-regulated-like (NDL) proteins interact with the Gβ subunit (AGB1) of the heterotrimeric G protein complex and play an important role in AGB1-dependent regulation of lateral root formation by affecting root auxin transport, auxin gradients and the steady-state levels of mRNA encoding the PIN-FORMED 2 and AUXIN 1 auxin transport facilitators. Auxin transport in aerial tissue follows different paths and utilizes different transporters than in roots; therefore, in the present study, we analyzed whether NDL proteins play an important role in AGB1-dependent, auxin-mediated meristem development. Expression levels of NDL gene family members need to be tightly regulated, and altered expression (both over-expression and down-regulation) confers ectopic growth. Over-expression of NDL1 disrupts vegetative and reproductive organ development. Reduced expression of the NDL gene family members results in asymmetric leaf emergence, twinning of rosette leaves, defects in leaf formation, and abnormal silique distribution. Reduced expression of the NDL genes in the agb1-2 (null allele) mutant rescues some of the abnormal phenotypes, such as silique morphology, silique distribution, and peduncle angle, suggesting that proper levels of NDL proteins are maintained by AGB1. We found that all of these abnormal aerial phenotypes due to altered NDL expression were associated with increases in basipetal auxin transport, altered auxin maxima and altered MAX2 expression within the inflorescence stem. NDL proteins, together with AGB1, act as positive regulators of meristem initiation and branching. AGB1 and NDL1 positively regulate basipetal inflorescence auxin transport and modulate MAX2 expression in shoots, which in turn regulates organ and lateral meristem formation by the establishment and maintenance of auxin gradients.

N-MYC DOWN-REGULATED-LIKE Proteins Regulate Meristem Initiation by Modulating Auxin Transport and MAX2 Expression

PubMed Central

Mudgil, Yashwanti; Ghawana, Sanjay; Jones, Alan M.

2013-01-01

Background N-MYC DOWN-REGULATED-LIKE (NDL) proteins interact with the Gβ subunit (AGB1) of the heterotrimeric G protein complex and play an important role in AGB1-dependent regulation of lateral root formation by affecting root auxin transport, auxin gradients and the steady-state levels of mRNA encoding the PIN-FORMED 2 and AUXIN 1 auxin transport facilitators. Auxin transport in aerial tissue follows different paths and utilizes different transporters than in roots; therefore, in the present study, we analyzed whether NDL proteins play an important role in AGB1-dependent, auxin-mediated meristem development. Methodology/Principal Findings Expression levels of NDL gene family members need to be tightly regulated, and altered expression (both over-expression and down-regulation) confers ectopic growth. Over-expression of NDL1 disrupts vegetative and reproductive organ development. Reduced expression of the NDL gene family members results in asymmetric leaf emergence, twinning of rosette leaves, defects in leaf formation, and abnormal silique distribution. Reduced expression of the NDL genes in the agb1-2 (null allele) mutant rescues some of the abnormal phenotypes, such as silique morphology, silique distribution, and peduncle angle, suggesting that proper levels of NDL proteins are maintained by AGB1. We found that all of these abnormal aerial phenotypes due to altered NDL expression were associated with increases in basipetal auxin transport, altered auxin maxima and altered MAX2 expression within the inflorescence stem. Conclusion/Significance NDL proteins, together with AGB1, act as positive regulators of meristem initiation and branching. AGB1 and NDL1 positively regulate basipetal inflorescence auxin transport and modulate MAX2 expression in shoots, which in turn regulates organ and lateral meristem formation by the establishment and maintenance of auxin gradients. PMID:24223735

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

PubMed Central

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

2017-01-01

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

Direct regulation of RNA polymerase III transcription by RB, p53 and c-Myc.

PubMed

Felton-Edkins, Zoë A; Kenneth, Niall S; Brown, Timothy R P; Daly, Nicole L; Gomez-Roman, Natividad; Grandori, Carla; Eisenman, Robert N; White, Robert J

2003-01-01

The synthesis of tRNA and 5S rRNA by RNA polymerase (pol) III is cell cycle regulated in higher organisms. Overexpression of pol III products is a general feature of transformed cells. These observations may be explained by the fact that a pol III-specific transcription factor, TFIIIB, is strongly regulated by the tumor suppressors RB and p53, as well as the proto-oncogene product c-Myc. RB and p53 repress TFIIIB, but this restraint can be lost in tumors through a variety of mechanisms. In contrast, c-Myc binds and activates TFIIIB, causing potent induction of pol III transcription. Using chromatin immunoprecipitation and RNA interference, we show that c-Myc interacts with tRNA and 5S rRNA genes in transformed cervical cells, stimulating their expression. Availability of pol III products may be an important determinant of a cell's capacity to grow. The ability to regulate pol III output may therefore be integral to the growth control functions of RB, p53 and c-Myc.

The Quest for Targets Executing MYC-Dependent Cell Transformation.

PubMed

Hartl, Markus

2016-01-01

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

The Quest for Targets Executing MYC-Dependent Cell Transformation

PubMed Central

Hartl, Markus

2016-01-01

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

MYC and the Control of DNA Replication

PubMed Central

Dominguez-Sola, David; Gautier, Jean

2014-01-01

The MYC oncogene is a multifunctional protein that is aberrantly expressed in a significant fraction of tumors from diverse tissue origins. Because of its multifunctional nature, it has been difficult to delineate the exact contributions of MYC’s diverse roles to tumorigenesis. Here, we review the normal role of MYC in regulating DNA replication as well as its ability to generate DNA replication stress when overexpressed. Finally, we discuss the possible mechanisms by which replication stress induced by aberrant MYC expression could contribute to genomic instability and cancer. PMID:24890833

The E3 ligase Mule protects the heart against oxidative stress and mitochondrial dysfunction through Myc-dependent inactivation of Pgc-1α and Pink1.

PubMed

Dadson, Keith; Hauck, Ludger; Hao, Zhenyue; Grothe, Daniela; Rao, Vivek; Mak, Tak W; Billia, Filio

2017-02-02

Cardiac homeostasis requires proper control of protein turnover. Protein degradation is principally controlled by the Ubiquitin-Proteasome System. Mule is an E3 ubiquitin ligase that regulates cellular growth, DNA repair and apoptosis to maintain normal tissue architecture. However, Mule's function in the heart has yet to be described. In a screen, we found reduced Mule expression in left ventricular samples from end-stage heart failure patients. Consequently, we generated conditional cardiac-specific Mule knockout (Mule  fl/fl(y) ;mcm) mice. Mule ablation in adult Mule  fl/fl(y) ;mcm mice prevented myocardial c-Myc polyubiquitination, leading to c-Myc accumulation and subsequent reduced expression of Pgc-1α, Pink1, and mitochondrial complex proteins. Furthermore, these mice developed spontaneous cardiac hypertrophy, left ventricular dysfunction, and early mortality. Co-deletion of Mule and c-Myc rescued this phenotype. Our data supports an indispensable role for Mule in cardiac homeostasis through the regulation of mitochondrial function via maintenance of Pgc-1α and Pink1 expression and persistent negative regulation of c-Myc.

Striking Similarity in the Gene Expression Levels of Individual Myc Module Members among ESCs, EpiSCs, and Partial iPSCs

PubMed Central

Hirasaki, Masataka; Hiraki-Kamon, Keiko; Kamon, Masayoshi; Suzuki, Ayumu; Katano, Miyuki; Nishimoto, Masazumi; Okuda, Akihiko

2013-01-01

Predominant transcriptional subnetworks called Core, Myc, and PRC modules have been shown to participate in preservation of the pluripotency and self-renewality of embryonic stem cells (ESCs). Epiblast stem cells (EpiSCs) are another cell type that possesses pluripotency and self-renewality. However, the roles of these modules in EpiSCs have not been systematically examined to date. Here, we compared the average expression levels of Core, Myc, and PRC module genes between ESCs and EpiSCs. EpiSCs showed substantially higher and lower expression levels of PRC and Core module genes, respectively, compared with those in ESCs, while Myc module members showed almost equivalent levels of average gene expression. Subsequent analyses revealed that the similarity in gene expression levels of the Myc module between these two cell types was not just overall, but striking similarities were evident even when comparing the expression of individual genes. We also observed equivalent levels of similarity in the expression of individual Myc module genes between induced pluripotent stem cells (iPSCs) and partial iPSCs that are an unwanted byproduct generated during iPSC induction. Moreover, our data demonstrate that partial iPSCs depend on a high level of c-Myc expression for their self-renewal properties. PMID:24386274

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

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 Central

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

2017-01-01

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. PMID:28470669

[Effect of methyl tertiary butyl ether on the expression of proto-oncogenes and function genes].

PubMed

Zhou, W; Huang, G; Zhang, H

1999-05-30

Methyl tertiary butyl ether (MTBE) is a new gasoline additive, which is used to increase the combustion of gasoline and to reduce the emission of harmful exhaust from automobile. The mechanism for the carcinogenesis of MTBE in animals is not clear. Immunohistochemistry method was used to detect the effect of MTBE on the expression of c-myc and p21 proteins in NIH3T3 cells. Dot hybridization method was used to explore the expression of c-myc gene and GST-P(glutathione S-transferase-P) gene in the of MTBE treated rats. The results showed that MTBE could enhance the expression of c-myc protein, but had no effect on p21 protein. MTBE could induce high expression of c-myc gene, and had no effect on the expression of GST-P gene. These results suggest that the high expression of c-myc gene induced by MTBE might be one of the mechanisms of its carcinogenicity in animal.

A balance of Mad and Myc expression dictates larval cell apoptosis and adult stem cell development during Xenopus intestinal metamorphosis.

PubMed

Okada, Morihiro; Miller, Thomas C; Wen, Luan; Shi, Yun-Bo

2017-05-11

The Myc/Mad/Max network has long been shown to be an important factor in regulating cell proliferation, death and differentiation in diverse cell types. In general, Myc-Max heterodimers activate target gene expression to promote cell proliferation, although excess of c-Myc can also induce apoptosis. In contrast, Mad competes against Myc to form Mad-Max heterodimers that bind to the same target genes to repress their expression and promote differentiation. The role of the Myc/Mad/Max network during vertebrate development, especially, the so-called postembryonic development, a period around birth in mammals, is unclear. Using thyroid hormone (T3)-dependent Xenopus metamorphosis as a model, we show here that Mad1 is induced by T3 in the intestine during metamorphosis when larval epithelial cell death and adult epithelial stem cell development take place. More importantly, we demonstrate that Mad1 is expressed in the larval cells undergoing apoptosis, whereas c-Myc is expressed in the proliferating adult stem cells during intestinal metamorphosis, suggesting that Mad1 may have a role in cell death during development. By using transcription activator-like effector nuclease-mediated gene-editing technology, we have generated Mad1 knockout Xenopus animals. This has revealed that Mad1 is not essential for embryogenesis or metamorphosis. On the other hand, consistent with its spatiotemporal expression profile, Mad1 knockout leads to reduced larval epithelial apoptosis but surprisingly also results in increased adult stem cell proliferation. These findings not only reveal a novel role of Mad1 in regulating developmental cell death but also suggest that a balance of Mad and Myc controls cell fate determination during adult organ development.

Regulation of c–myc expression by IFN–γ through Stat1-dependent and -independent pathways

PubMed Central

Ramana, Chilakamarti V.; Grammatikakis, Nicholas; Chernov, Mikhail; Nguyen, Hannah; Goh, Kee Chuan; Williams, Bryan R.G.; Stark, George R.

2000-01-01

Interferons (IFNs) inhibit cell growth in a Stat1-dependent fashion that involves regulation of c–myc expression. IFN–γ suppresses c–myc in wild-type mouse embryo fibroblasts, but not in Stat1-null cells, where IFNs induce c–myc mRNA rapidly and transiently, thus revealing a novel signaling pathway. Both tyrosine and serine phosphorylation of Stat1 are required for suppression. Induced expression of c–myc is likely to contribute to the proliferation of Stat1-null cells in response to IFNs. IFNs also suppress platelet-derived growth factor (PDGF)-induced c–myc expression in wild-type but not in Stat1-null cells. A gamma-activated sequence element in the promoter is necessary but not sufficient to suppress c–myc expression in wild-type cells. In PKR-null cells, the phosphorylation of Stat1 on Ser727 and transactivation are both defective, and c–myc mRNA is induced, not suppressed, in response to IFN–γ. A role for Raf–1 in the Stat1-independent pathway is revealed by studies with geldanamycin, an HSP90-specific inhibitor, and by expression of a mutant of p50cdc37 that is unable to recruit HSP90 to the Raf–1 complex. Both agents abrogated the IFN–γ-dependent induction of c–myc expression in Stat1-null cells. PMID:10637230

Long non-coding RNA HOTAIR, a c-Myc activated driver of malignancy, negatively regulates miRNA-130a in gallbladder cancer

PubMed Central

2014-01-01

Background Protein coding genes account for only about 2% of the human genome, whereas the vast majority of transcripts are non-coding RNAs including long non-coding RNAs. A growing volume of literature has proposed that lncRNAs are important players in cancer. HOTAIR was previously shown to be an oncogene and negative prognostic factor in a variety of cancers. However, the factors that contribute to its upregulation and the interaction between HOTAIR and miRNAs are largely unknown. Methods A computational screen of HOTAIR promoter was conducted to search for transcription-factor-binding sites. HOTAIR promoter activities were examined by luciferase reporter assay. The function of the c-Myc binding site in the HOTAIR promoter region was tested by a promoter assay with nucleotide substitutions in the putative E-box. The association of c-Myc with the HOTAIR promoter in vivo was confirmed by chromatin immunoprecipitation assay and Electrophoretic mobility shift assay. A search for miRNAs with complementary base paring with HOTAIR was performed utilizing online software program. Gain and loss of function approaches were employed to investigate the expression changes of HOTAIR or miRNA-130a. The expression levels of HOTAIR, c-Myc and miRNA-130a were examined in 65 matched pairs of gallbladder cancer tissues. The effects of HOTAIR and miRNA-130a on gallbladder cancer cell invasion and proliferation was tested using in vitro cell invasion and flow cytometric assays. Results We demonstrate that HOTAIR is a direct target of c-Myc through interaction with putative c-Myc target response element (RE) in the upstream region of HOTAIR in gallbladder cancer cells. A positive correlation between c-Myc and HOTAIR mRNA levels was observed in gallbladder cancer tissues. We predicted that HOTAIR harbors a miRNA-130a binding site. Our data showed that this binding site is vital for the regulation of miRNA-130a by HOTAIR. Moreover, a negative correlation between HOTAIR and miRNA-130a was

MYC copy number gains are associated with poor outcome in penile squamous cell carcinoma.

PubMed

Masferrer, Emili; Ferrándiz-Pulido, Carla; Lloveras, Belén; Masferrer-Niubò, Magalí; Espinet, Blanca; Salido, Marta; Rodríguez-Rivera, María; Alemany, Laia; Placer, Jose; Gelabert, Antoni; Servitje, Octavi; García-Patos, Vicenç; Pujol, Ramon M; Toll, Agustí

2012-11-01

We determined MYC gene numerical aberrations and protein expression at different stages of penile squamous cell carcinoma carcinogenesis. We correlated these findings with clinicopathological parameters and HPV infection. We evaluated 79 cases of penile squamous cell carcinoma, including 11 in situ and 68 invasive carcinomas. The MYC cytogenetic profile was evaluated by fluorescence in situ hybridization. HPV was detected by polymerase chain reaction amplification. MYC gains were identified in 4 of 11 in situ carcinomas (36%) and 50 of 68 invasive penile squamous cell carcinomas (73%). A significant association between MYC gains, and tumor progression and poor outcome was demonstrated (p <0.05). HPV DNA was detected in 32 of 79 penile squamous cell carcinomas (39%). High risk type 16 was the most prevalent type. MYC numerical aberrations did not correlate with HPV status. A significant association between HPV and MYC protein over expression was noted. In HPV negative cases MYC gains correlated with MYC over expression. MYC gains progressively increased during penile squamous cell carcinoma progression from in situ samples to metastases. MYC gains were an independent factor for poor prognosis. These findings were independent of HPV infection. MYC expression was increased in samples with HPV infection, probably reflecting direct activation of MYC. Copyright © 2012 American Urological Association Education and Research, Inc. Published by Elsevier Inc. All rights reserved.

Sequence specific peptidomimetic molecules inhibitors of a protein-protein interaction at the helix 1 level of c-Myc.

PubMed

Nieddu, Erika; Melchiori, A; Pescarolo, M P; Bagnasco, L; Biasotti, B; Licheri, B; Malacarne, D; Tortolina, L; Castagnino, N; Pasa, S; Cimoli, G; Avignolo, C; Ponassi, R; Balbi, C; Patrone, E; D'arrigo, C; Barboro, P; Vasile, F; Orecchia, P; Carnemolla, B; Damonte, G; Millo, E; Palomba, D; Fassina, G; Mazzei, M; Parodi, S

2005-04-01

Our work is focused in the broad area of strategies and efforts to inhibit protein-protein interactions. The possible strategies in this field are definitely much more varied than in the case of ATP-pocket inhibitors. In our previous work (10), we reported that a retro-inverso (RI) form of Helix1 (H1) of c-Myc, linked to an RI-internalization sequence arising from the third alpha-helix of Antennapedia (Int) was endowed with an antiproliferative and proapoptotic activity toward the cancer cell lines MCF-7 and HCT-116. The activity apparently was dependent upon the presence of the Myc motif. In this work, by ala-scan mapping of the H1 portion of our molecules with D-aa, we found two amino acids necessary for antiproliferative activity: D-Lys in 4 and D-Arg in 5 (numbers refer to L-forms). In the natural hetero-dimer, these two side chains project to the outside of the four alpha-helix bundle. Moreover, we were able to obtain three peptides more active than the original lead. They strongly reduced cell proliferation and survival (RI-Int-VV-H1-E2A,S6A,F8A; RI-Int-VV-H1-S6A,F8A,R11A; RI-Int-VV-H1-S6A,F8A,Q13A): after 8 days at 10 muM total cell number was approximately 1% of the number of cells initially seeded. In these more potent molecules, the ablated side chains project to the inside in the corresponding natural four alpha-helix bundle. In the present work, we also investigated the behavior of our molecules at the biochemical level. Using both a circular dichroism (CD) and a fluorescence anisotropy approach, we noted that side chains projecting at the interior of the four alpha-helix bundle are needed for inducing the partial unfolding of Myc-H2, without an opening of the leucine zipper. Side chains projecting at the outside are not required for this biochemical effect. However, antiproliferative activity had the opposite requirements: side chains projecting at the outside of the bundle were essential, and, on the contrary, ablation of one side chain at a time

SALL4 as an Epithelial-Mesenchymal Transition and Drug Resistance Inducer through the Regulation of c-Myc in Endometrial Cancer

PubMed Central

Yang, Xiaoming; Fang, Chi; Xu, Huali; Xi, Xiaowei

2015-01-01

SALL4 plays important roles in the development and progression of many cancers. However, the role and molecular mechanism of SALL4 in endometrial cancer remain elusive. In the present research, we have demonstrated that the expression of SALL4 was upregulated in endometrial cancer and correlated positively with tumor stage, metastases and poor survival of patients. The overexpression of SALL4 promoted the invasiveness in endometrial cancer cells, as indicated by the upregulation of mesenchymal cell marker N-cadherin and downregulation of the epithelial marker E-cadherin, and invasion assays in vitro. Additionally, there was also an increase in drug resistance in these cell models due to the upregulation of ATP-binding cassette multidrug transporter ABCB1 expression. Moreover, we also found that ABCB1 was critical for SALL4-induced drug resistance. In contrast, SALL4 knockdown restored drug sensitivity, reversed EMT, diminished cell metastasis and suppressed the downregulation of E-cadherin and the upregulation of N-cadherin and ABCB1. Furthermore, we showed that SALL4 upregulated c-Myc expression and c-Myc was a direct target for SALL4 by ChIP assay, depletion of c-Myc with siRNA abolished the SALL4-induced downregulation of E-cadherin, upregulation of N-cadherin and ABCB1, suggesting that c-Myc was a downstream target for SALL4 and required for SALL4-induced EMT, invasion and drugs resistance in endometrial cancer cells. These results indicated that SALL4 could induce EMT and resistance to antineoplastic drugs through the regulation of c-Myc. SALL4 and c-Myc may be novel therapeutic targets for endometrial cancer. PMID:26407074

27-Hydroxycholesterol increases Myc protein stability via suppressing PP2A, SCP1 and FBW7 transcription in MCF-7 breast cancer cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ma, Li-Ming; Liang, Zi-Rui; Zhou, Ke-Ren

27-hydroxycholesterol (27-HC), the most abundant metabolite of cholesterol, is a risk factor for breast cancer. It can increase the proliferation of breast cancer cells and promote the metastasis of breast tumours in mouse models. Myc is a critical oncoprotein overexpressed in breast cancer. However, whether 27-HC affects Myc expression has not been reported. In the current study, we aimed to investigate the effects of 27-HC on Myc and the underlying mechanisms in MCF-7 breast cancer cells. Our data demonstrated that 27-HC activated Myc via increasing its protein stability. Three key negative modulators of Myc protein stability, PP2A, SCP1 and FBW7,more » were suppressed by 27-HC at the transcriptional level. We performed a data-mining analysis of the chromatin immunoprecipitation with next-generation DNA sequencing (ChIP-Seq) data in the ChIPBase, and discovered that a number of putative transcription factors (TFs), including Myc itself, were involved in the transcriptional regulation of PP2A, SCP1 and FBW7. Our results provide a novel mechanistic insight into the activation of Myc by 27-HC via transcriptional repression of PP2A, SCP1 and FBW7 to increase Myc protein stability in breast cancer cells. - Highlights: • 27-Hydroxycholesterol (27-HC) activates Myc via increasing its protein stability. • 27-HC inhibits PP2A and SCP1 transcription to block pS62-Myc dephosphorylation. • 27-HC suppresses FBW7 transcription to prevent pT58-Myc degradation.« less

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.

Myc-driven overgrowth requires unfolded protein response-mediated induction of autophagy and antioxidant responses in Drosophila melanogaster.

PubMed

Nagy, Péter; Varga, Agnes; Pircs, Karolina; Hegedűs, Krisztina; Juhász, Gábor

2013-01-01

Autophagy, a lysosomal self-degradation and recycling pathway, plays dual roles in tumorigenesis. Autophagy deficiency predisposes to cancer, at least in part, through accumulation of the selective autophagy cargo p62, leading to activation of antioxidant responses and tumor formation. While cell growth and autophagy are inversely regulated in most cells, elevated levels of autophagy are observed in many established tumors, presumably mediating survival of cancer cells. Still, the relationship of autophagy and oncogenic signaling is poorly characterized. Here we show that the evolutionarily conserved transcription factor Myc (dm), a proto-oncogene involved in cell growth and proliferation, is also a physiological regulator of autophagy in Drosophila melanogaster. Loss of Myc activity in null mutants or in somatic clones of cells inhibits autophagy. Forced expression of Myc results in cell-autonomous increases in cell growth, autophagy induction, and p62 (Ref2P)-mediated activation of Nrf2 (cnc), a transcription factor promoting antioxidant responses. Mechanistically, Myc overexpression increases unfolded protein response (UPR), which leads to PERK-dependent autophagy induction and may be responsible for p62 accumulation. Genetic or pharmacological inhibition of UPR, autophagy or p62/Nrf2 signaling prevents Myc-induced overgrowth, while these pathways are dispensable for proper growth of control cells. In addition, we show that the autophagy and antioxidant pathways are required in parallel for excess cell growth driven by Myc. Deregulated expression of Myc drives tumor progression in most human cancers, and UPR and autophagy have been implicated in the survival of Myc-dependent cancer cells. Our data obtained in a complete animal show that UPR, autophagy and p62/Nrf2 signaling are required for Myc-dependent cell growth. These novel results give additional support for finding future approaches to specifically inhibit the growth of cancer cells addicted to oncogenic

Selective targeting of the repressive transcription factors YY1 and cMyc to disrupt quiescent human immunodeficiency viruses.

PubMed

Barton, Kirston; Margolis, David

2013-02-01

Quiescent HIV-1 infection of resting CD4(+) T cells is an obstacle to eradication of HIV-1 infection. These reservoirs are maintained, in part, by repressive complexes that bind to the HIV-1 long terminal repeat (LTR) and recruit histone deacetylases (HDACs). cMyc and YY1 are two transcription factors that are recruited as part of well-described, distinct complexes to the HIV-1 LTR and in turn recruit HDACs. In prior studies, depletion of single factors that recruit HDAC1 in various cell lines was sufficient to upregulate LTR activity. We used short hairpin RNAs (shRNAs) to test the effect of targeted disruption of a single transcription factor on quiescent proviruses in T cell lines. In this study, we found that depletion of YY1 significantly increases mRNA and protein expression from the HIV-1 promoter in some contexts, but does not affect HDAC1, HDAC2, HDAC3, or acetylated histone 3 occupancy of the HIV-1 LTR. Conversely, depletion of cMyc or cMyc and YY1 does not significantly alter the level of transcription from the LTR or affect recruitment of HDACs to the HIV-1 LTR. Furthermore, global inhibition of HDACs with the HDAC inhibitor suberoylanilide hydroxamic acid (SAHA) enhanced the increase in LTR transcription in cells that were depleted of YY1.These findings show that despite prior isolated findings, redundancy in repressors of HIV-1 LTR expression will require selective targeting of multiple restrictive mechanisms to comprehensively induce the escape of quiescent proviruses from latency.

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

PubMed

Pastor, Tibor; Popović, Branka; Gvozdenović, Ana; Boro, Aleksandar; Petrović, Bojana; Novaković, Ivana; Puzović, Dragana; Luković, Ljiljana; Milasin, Jelena

2009-01-01

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

A balance of Mad and Myc expression dictates larval cell apoptosis and adult stem cell development during Xenopus intestinal metamorphosis

PubMed Central

Okada, Morihiro; Miller, Thomas C; Wen, Luan; Shi, Yun-Bo

2017-01-01

The Myc/Mad/Max network has long been shown to be an important factor in regulating cell proliferation, death and differentiation in diverse cell types. In general, Myc–Max heterodimers activate target gene expression to promote cell proliferation, although excess of c-Myc can also induce apoptosis. In contrast, Mad competes against Myc to form Mad–Max heterodimers that bind to the same target genes to repress their expression and promote differentiation. The role of the Myc/Mad/Max network during vertebrate development, especially, the so-called postembryonic development, a period around birth in mammals, is unclear. Using thyroid hormone (T3)-dependent Xenopus metamorphosis as a model, we show here that Mad1 is induced by T3 in the intestine during metamorphosis when larval epithelial cell death and adult epithelial stem cell development take place. More importantly, we demonstrate that Mad1 is expressed in the larval cells undergoing apoptosis, whereas c-Myc is expressed in the proliferating adult stem cells during intestinal metamorphosis, suggesting that Mad1 may have a role in cell death during development. By using transcription activator-like effector nuclease-mediated gene-editing technology, we have generated Mad1 knockout Xenopus animals. This has revealed that Mad1 is not essential for embryogenesis or metamorphosis. On the other hand, consistent with its spatiotemporal expression profile, Mad1 knockout leads to reduced larval epithelial apoptosis but surprisingly also results in increased adult stem cell proliferation. These findings not only reveal a novel role of Mad1 in regulating developmental cell death but also suggest that a balance of Mad and Myc controls cell fate determination during adult organ development. PMID:28492553

Tea polyphenols can restrict benzo[a]pyrene-induced lung carcinogenesis by altered expression of p53-associated genes and H-ras, c-myc and cyclin D1.

PubMed

Manna, Sugata; Mukherjee, Sudeshna; Roy, Anup; Das, Sukta; Panda, Chinmay Kr

2009-05-01

The modulatory influence of tea polyphenols (epigallocatechin gallate, epicatechin gallate and theaflavin) on benzo[a]pyrene (B[a]P)-induced lung carcinogenesis in mice was analyzed using histopathological and molecular parameters. Progression of lung lesions was restricted at the hyperplastic stage by tea polyphenols. A significant reduction in cellular proliferative index and an increase in apoptotic index were noted in the restricted lung lesions. High expression of H-ras, c-myc, cyclin D1 and p53 genes was seen at the inflammatory stage (9th week) and in subsequent premalignant lesions, but down-regulation of H-ras at the hyperplastic stage (17th week). Expression of bcl-2 was high in hyperplastic lesions, whereas the expression of mdm2 and bcl-xl increased only at the moderately dysplastic stage (36th week). The tea polyphenols inhibited inflammatory response in the lung lesions on the 9th week, when decreased expression of H-ras and c-myc and increased expression of bax were noted. Prolonged treatment (>9th week) with tea polyphenols resulted in changes in the expression of some additional genes, such as reduced expression of cyclin D1 (from the 17th week), bcl-2 (from the 26th week; mild dysplasia) and p21 (on the 36th week), and high expression of p53 (from the 17th week) and p27 (on the 36th week). These observations indicate that the tea polyphenols can restrict B[a]P-induced lung carcinogenesis by differential modulation of the expression of p53 and its associated genes such as bax, bcl-2, mdm2, p21 and p27, along with H-ras, c-myc and cyclin D1, at different time points.

Telomerase activation by c-Myc in human mammary epithelial cells requires additional genomic changes.

PubMed

Bazarov, Alexey V; Hines, William C; Mukhopadhyay, Rituparna; Beliveau, Alain; Melodyev, Sonya; Zaslavsky, Yuri; Yaswen, Paul

2009-10-15

A central question in breast cancer biology is how cancer cells acquire telomerase activity required for unlimited proliferation. According to one model, proliferation of telomerase(-) pre-malignant cells leads to telomere dysfunction and increased genomic instability. Such instability leads in rare cases to reactivation of telomerase and immortalization. The mechanism of telomerase reactivation remains unknown. We have studied immortalization of cultured human mammary epithelial cells by c-Myc, a positive transcriptional regulator of the hTERT gene encoding the catalytic subunit of telomerase. Retrovirally introduced c-Myc cDNA resulted in immortalization of human mammary epithelial cells in which the cyclin dependent kinase inhibitor, p16(INK4A), was inactivated by an shRNA-encoding retrovirus. However, while c-Myc introduction immediately resulted in increased activity of transiently transfected hTERT promoter reporter constructs, endogenous hTERT mRNA levels did not change until about 60 population doublings after c-Myc introduction. Increased endogenous hTERT transcripts and stabilization of telomeric DNA in cells expressing exogenous c-Myc coincided with telomere dysfunction-associated senescence in control cultures. Genome copy number analyses of immortalized cells indicated amplifications of some or all of chromosome 5, where hTERT genes are located. hTERT gene copy number, however, was not increased in one case. The results are consistent with the hypothesis that changes in chromosome 5, while not necessarily increasing hTERT gene copy number, resulted in removal of repressive chromatin structures around hTERT loci, allowing induction of hTERT transcription. These in vitro results model one possible sequence of events leading to immortalization of breast epithelial cells during cancer progression.

An oncogenic axis of STAT-mediated BATF3 upregulation causing MYC activity in classical Hodgkin lymphoma and anaplastic large cell lymphoma.

PubMed

Lollies, A; Hartmann, S; Schneider, M; Bracht, T; Weiß, A L; Arnolds, J; Klein-Hitpass, L; Sitek, B; Hansmann, M-L; Küppers, R; Weniger, M A

2018-01-01

Classical Hodgkin lymphoma (cHL) and anaplastic large cell lymphoma (ALCL) feature high expression of activator protein-1 (AP-1) transcription factors, which regulate various physiological processes but also promote lymphomagenesis. The AP-1 factor basic leucine zipper transcription factor, ATF-like 3 (BATF3), is highly transcribed in cHL and ALCL; however, its functional importance in lymphomagenesis is unknown. Here we show that proto-typical CD30 + lymphomas, namely cHL (21/30) and primary mediastinal B-cell lymphoma (8/9), but also CD30 + diffuse large B-cell lymphoma (15/20) frequently express BATF3 protein. Mass spectrometry and co-immunoprecipitation established interactions of BATF3 with JUN and JUNB in cHL and ALCL lines. BATF3 knockdown using short hairpin RNAs was toxic for cHL and ALCL lines, reducing their proliferation and survival. We identified MYC as a critical BATF3 target and confirmed binding of BATF3 to the MYC promoter. JAK/STAT signaling regulated BATF3 expression, as chemical JAK2 inhibition reduced and interleukin 13 stimulation induced BATF3 expression in cHL lines. Chromatin immunoprecipitation substantiated a direct regulation of BATF3 by STAT proteins in cHL and ALCL lines. In conclusion, we identified STAT-mediated BATF3 expression that is essential for lymphoma cell survival and promoted MYC activity in cHL and ALCL, hence we recognized a new oncogenic axis in these lymphomas.

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

APTO-253 Stabilizes G-quadruplex DNA, Inhibits MYC Expression, and Induces DNA Damage in Acute Myeloid Leukemia Cells.

PubMed

Local, Andrea; Zhang, Hongying; Benbatoul, Khalid D; Folger, Peter; Sheng, Xia; Tsai, Cheng-Yu; Howell, Stephen B; Rice, William G

2018-06-01

APTO-253 is a phase I clinical stage small molecule that selectively induces CDKN1A (p21), promotes G 0 -G 1 cell-cycle arrest, and triggers apoptosis in acute myeloid leukemia (AML) cells without producing myelosuppression in various animal species and humans. Differential gene expression analysis identified a pharmacodynamic effect on MYC expression, as well as induction of DNA repair and stress response pathways. APTO-253 was found to elicit a concentration- and time-dependent reduction in MYC mRNA expression and protein levels. Gene ontogeny and structural informatic analyses suggested a mechanism involving G-quadruplex (G4) stabilization. Intracellular pharmacokinetic studies in AML cells revealed that APTO-253 is converted intracellularly from a monomer to a ferrous complex [Fe(253) 3 ]. FRET assays demonstrated that both monomeric APTO-253 and Fe(253) 3 stabilize G4 structures from telomeres, MYC, and KIT promoters but do not bind to non-G4 double-stranded DNA. Although APTO-253 exerts a host of mechanistic sequelae, the effect of APTO-253 on MYC expression and its downstream target genes, on cell-cycle arrest, DNA damage, and stress responses can be explained by the action of Fe(253) 3 and APTO-253 on G-quadruplex DNA motifs. Mol Cancer Ther; 17(6); 1177-86. ©2018 AACR . ©2018 American Association for Cancer Research.

A dual tag system for facilitated detection of surface expressed proteins in Escherichia coli

PubMed Central

2012-01-01

Background The discovery of the autotransporter family has provided a mechanism for surface expression of proteins in laboratory strains of Escherichia coli. We have previously reported the use of the AIDA-I autotransport system to express the Salmonella enterica serovar Enteritidis proteins SefA and H:gm. The SefA protein was successfully exposed to the medium, but the orientation of H:gm in the outer membrane could not be determined due to proteolytic cleavage of the N-terminal detection-tag. The goal of the present work was therefore to construct a vector containing elements that facilitates analysis of surface expression, especially for proteins that are sensitive to proteolysis or otherwise difficult to express. Results The surface expression system pAIDA1 was created with two detection tags flanking the passenger protein. Successful expression of SefA and H:gm on the surface of E. coli was confirmed with fluorescently labeled antibodies specific for the N-terminal His6-tag and the C-terminal Myc-tag. While both tags were detected during SefA expression, only the Myc-tag could be detected for H:gm. The negative signal indicates a proteolytic cleavage of this protein that removes the His6-tag facing the medium. Conclusions Expression levels from pAIDA1 were comparable to or higher than those achieved with the formerly used vector. The presence of the Myc- but not of the His6-tag on the cell surface during H:gm expression allowed us to confirm the hypothesis that this fusion protein was present on the surface and oriented towards the cell exterior. Western blot analysis revealed degradation products of the same molecular weight for SefA and H:gm. The size of these fragments suggests that both fusion proteins have been cleaved at a specific site close to the C-terminal end of the passenger. This proteolysis was concluded to take place either in the outer membrane or in the periplasm. Since H:gm was cleaved to a much greater extent then the three times smaller Sef

Multistage modeling of protein dynamics with monomeric Myc oncoprotein as an example.

PubMed

Liu, Jiaojiao; Dai, Jin; He, Jianfeng; Niemi, Antti J; Ilieva, Nevena

2017-03-01

We propose to combine a mean-field approach with all-atom molecular dynamics (MD) into a multistage algorithm that can model protein folding and dynamics over very long time periods yet with atomic-level precision. As an example, we investigate an isolated monomeric Myc oncoprotein that has been implicated in carcinomas including those in colon, breast, and lungs. Under physiological conditions a monomeric Myc is presumed to be an example of intrinsically disordered proteins that pose a serious challenge to existing modeling techniques. We argue that a room-temperature monomeric Myc is in a dynamical state, it oscillates between different conformations that we identify. For this we adopt the Cα backbone of Myc in a crystallographic heteromer as an initial ansatz for the monomeric structure. We construct a multisoliton of the pertinent Landau free energy to describe the Cα profile with ultrahigh precision. We use Glauber dynamics to resolve how the multisoliton responds to repeated increases and decreases in ambient temperature. We confirm that the initial structure is unstable in isolation. We reveal a highly degenerate ground-state landscape, an attractive set towards which Glauber dynamics converges in the limit of vanishing ambient temperature. We analyze the thermal stability of this Glauber attractor using room-temperature molecular dynamics. We identify and scrutinize a particularly stable subset in which the two helical segments of the original multisoliton align in parallel next to each other. During the MD time evolution of a representative structure from this subset, we observe intermittent quasiparticle oscillations along the C-terminal α helix, some of which resemble a translating Davydov's Amide-I soliton. We propose that the presence of oscillatory motion is in line with the expected intrinsically disordered character of Myc.

Silencing c-Myc translation as a therapeutic strategy through targeting PI3Kδ and CK1ε in hematological malignancies.

PubMed

Deng, Changchun; Lipstein, Mark R; Scotto, Luigi; Jirau Serrano, Xavier O; Mangone, Michael A; Li, Shirong; Vendome, Jeremie; Hao, Yun; Xu, Xiaoming; Deng, Shi-Xian; Realubit, Ronald B; Tatonetti, Nicholas P; Karan, Charles; Lentzsch, Suzanne; Fruman, David A; Honig, Barry; Landry, Donald W; O'Connor, Owen A

2017-01-05

Phosphoinositide 3-kinase (PI3K) and the proteasome pathway are both involved in activating the mechanistic target of rapamycin (mTOR). Because mTOR signaling is required for initiation of messenger RNA translation, we hypothesized that cotargeting the PI3K and proteasome pathways might synergistically inhibit translation of c-Myc. We found that a novel PI3K δ isoform inhibitor TGR-1202, but not the approved PI3Kδ inhibitor idelalisib, was highly synergistic with the proteasome inhibitor carfilzomib in lymphoma, leukemia, and myeloma cell lines and primary lymphoma and leukemia cells. TGR-1202 and carfilzomib (TC) synergistically inhibited phosphorylation of the eukaryotic translation initiation factor 4E (eIF4E)-binding protein 1 (4E-BP1), leading to suppression of c-Myc translation and silencing of c-Myc-dependent transcription. The synergistic cytotoxicity of TC was rescued by overexpression of eIF4E or c-Myc. TGR-1202, but not other PI3Kδ inhibitors, inhibited casein kinase-1 ε (CK1ε). Targeting CK1ε using a selective chemical inhibitor or short hairpin RNA complements the effects of idelalisib, as a single agent or in combination with carfilzomib, in repressing phosphorylation of 4E-BP1 and the protein level of c-Myc. These results suggest that TGR-1202 is a dual PI3Kδ/CK1ε inhibitor, which may in part explain the clinical activity of TGR-1202 in aggressive lymphoma not found with idelalisib. Targeting CK1ε should become an integral part of therapeutic strategies targeting translation of oncogenes such as c-Myc. © 2017 by The American Society of Hematology.

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

Reprogramming of proline and glutamine metabolism contributes to the proliferative and metabolic responses regulated by oncogenic transcription factor c-MYC

PubMed Central

Liu, Wei; Le, Anne; Hancock, Chad; Lane, Andrew N.; Dang, Chi V.; Fan, Teresa W.-M.; Phang, James M.

2012-01-01

In addition to glycolysis, the oncogenic transcription factor c-MYC (MYC) stimulates glutamine catabolism to fuel growth and proliferation of cancer cells through up-regulating glutaminase (GLS). Glutamine is converted to glutamate by GLS, entering the tricarboxylic acid cycle as an important energy source. Less well-recognized, glutamate can also be converted to proline through Δ1-pyrroline-5-carboxylate (P5C) and vice versa. This study suggests that some MYC-induced cellular effects are due to MYC regulation of proline metabolism. Proline oxidase, also known as proline dehydrogenase (POX/PRODH), the first enzyme in proline catabolism, is a mitochondrial tumor suppressor that inhibits proliferation and induces apoptosis. MiR-23b* mediates POX/PRODH down-regulation in human kidney tumors. MiR-23b* is processed from the same transcript as miR-23b; the latter inhibits the translation of GLS. Using MYC-inducible human Burkitt lymphoma model P493 and PC3 human prostate cancer cells, we showed that MYC suppressed POX/PRODH expression primarily through up-regulating miR-23b*. The growth inhibition in the absence of MYC was partially reversed by POX/PRODH knockdown, indicating the importance of suppression of POX/PRODH in MYC-mediated cellular effects. Interestingly, MYC not only inhibited POX/PRODH, but also markedly increased the enzymes of proline biosynthesis from glutamine, including P5C synthase and P5C reductase 1. MYC-induced proline biosynthesis from glutamine was directly confirmed using 13C,15N-glutamine as a tracer. The metabolic link between glutamine and proline afforded by MYC emphasizes the complexity of tumor metabolism. Further studies of the relationship between glutamine and proline metabolism should provide a deeper understanding of tumor metabolism while enabling the development of novel therapeutic strategies. PMID:22615405

FBW7 (F-box and WD Repeat Domain-Containing 7) Negatively Regulates Glucose Metabolism by Targeting the c-Myc/TXNIP (Thioredoxin-Binding Protein) Axis in Pancreatic Cancer.

PubMed

Ji, Shunrong; Qin, Yi; Liang, Chen; Huang, Run; Shi, Si; Liu, Jiang; Jin, Kaizhou; Liang, Dingkong; Xu, Wenyan; Zhang, Bo; Liu, Liang; Liu, Chen; Xu, Jin; Ni, Quanxing; Chiao, Paul J; Li, Min; Yu, Xianjun

2016-08-01

FBW7 functions as a tumor suppressor by targeting oncoproteins for destruction. We previously reported that the oncogenic mutation of KRAS inhibits the tumor suppressor FBW7 via the Ras-Raf-MEK-ERK pathway, which facilitates the proliferation and survival of pancreatic cancer cells. However, the underlying mechanism by which FBW7 suppresses pancreatic cancer remains unexplored. Here, we sought to elucidate the function of FBW7 in pancreatic cancer glucose metabolism and malignancy. Combining maximum standardized uptake value (SUVmax), which was obtained preoperatively via a PET/CT scan, with immunohistochemistry staining, we analyzed the correlation between SUVmax and FBW7 expression in pancreatic cancer tissues. The impact of FBW7 on glucose metabolism was further validated in vitro and in vivo Finally, gene expression profiling was performed to identify core signaling pathways. The expression level of FBW7 was negatively associated with SUVmax in pancreatic cancer patients. FBW7 significantly suppressed glucose metabolism in pancreatic cancer cells in vitro Using a xenograft model, MicroPET/CT imaging results indicated that FBW7 substantially decreased 18F-fluorodeoxyglucose ((18)F-FDG) uptake in xenograft tumors. Gene expression profiling data revealed that TXNIP, a negative regulator of metabolic transformation, was a downstream target of FBW7. Mechanistically, we demonstrated that TXNIP was a c-Myc target gene and that FBW7 regulated TXNIP expression in a c-Myc-dependent manner. Our results thus reveal that FBW7 serves as a negative regulator of glucose metabolism through regulation of the c-Myc/TXNIP axis in pancreatic cancer. Clin Cancer Res; 22(15); 3950-60. ©2016 AACR. ©2016 American Association for Cancer Research.

Ndrg2 is a PGC-1α/ERRα target gene that controls protein synthesis and expression of contractile-type genes in C2C12 myotubes.

PubMed

Foletta, Victoria C; Brown, Erin L; Cho, Yoshitake; Snow, Rod J; Kralli, Anastasia; Russell, Aaron P

2013-12-01

The stress-responsive, tumor suppressor N-myc downstream-regulated gene 2 (Ndrg2) is highly expressed in striated muscle. In response to anabolic and catabolic signals, Ndrg2 is suppressed and induced, respectively, in mouse C2C12 myotubes. However, little is known about the mechanisms regulating Ndrg2 expression in muscle, as well as the biological role for Ndrg2 in differentiated myotubes. Here, we show that Ndrg2 is a target of a peroxisome proliferator-activated receptor-gamma coactivator-1α (PGC-1α) and estrogen-related receptor alpha (ERRα) transcriptional program and is induced in response to endurance exercise, a physiological stress known also to increase PGC-1α/ERRα activity. Analyses of global gene and protein expression profiles in C2C12 myotubes with reduced levels of NDRG2, suggest that NDRG2 affects muscle growth, contractile properties, MAPK signaling, ion and vesicle transport and oxidative phosphorylation. Indeed, suppression of NDRG2 in myotubes increased protein synthesis and the expression of fast glycolytic myosin heavy chain isoforms, while reducing the expression of embryonic myosin Myh3, other contractile-associated genes and the MAPK p90 RSK1. Conversely, enhanced expression of NDRG2 reduced protein synthesis, and furthermore, partially blocked the increased protein synthesis rates elicited by a constitutively active form of ERRα. In contrast, suppressing or increasing levels of NDRG2 did not affect mRNA expression of genes involved in mitochondrial biogenesis that are regulated by PGC-1α or ERRα. This study shows that in C2C12 myotubes Ndrg2 is a novel PGC-1α/ERRα transcriptional target, which influences protein turnover and the regulation of genes involved in muscle contraction and function. © 2013 Elsevier B.V. All rights reserved.

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

PubMed Central

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

2011-01-01

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

PIM kinase inhibition presents a novel targeted therapy against triple-negative breast tumors with elevated MYC expression

PubMed Central

Horiuchi, Dai; Camarda, Roman; Zhou, Alicia Y.; Yau, Christina; Momcilovic, Olga; Balakrishnan, Sanjeev; Corella, Alexandra N.; Eyob, Henok; Kessenbrock, Kai; Lawson, Devon A.; Marsh, Lindsey A.; Anderton, Brittany N.; Rohrberg, Julia; Kunder, Ratika; Bazarov, Alexey V.; Yaswen, Paul; McManus, Michael T.; Rugo, Hope S.; Werb, Zena; Goga, Andrei

2017-01-01

Triple-negative breast cancer (TNBC), which lacks the expression of the estrogen, progesterone, and HER2 receptors, represents the breast cancer subtype with the poorest outcome1. No targeted therapy is available against this subtype due to lack of validated molecular targets. We previously reported that MYC signaling is disproportionally elevated in triple-negative (TN) tumors compared to receptor-positive (RP) tumors2. MYC is an essential, pleiotropic transcription factor that regulates the expression of hundreds of genes3. Direct inhibition of oncogenic MYC transcriptional activity has remained challenging4,5. The present study conducted an shRNA screen against all kinases to uncover novel MYC-dependent synthetic lethal combinations, and identified PIM1, a non-essential kinase. Here we demonstrate that PIM1 expression was elevated in TN tumors and was associated with poor prognosis in patients with hormone and HER2 receptor-negative tumors. Small molecule PIM kinase inhibitors halted the growth of human TN tumors with elevated MYC expression in patient-derived tumor xenograft (PDX) and MYC-driven transgenic breast cancer models by inhibiting oncogenic transcriptional activity of MYC while simultaneously restoring the function of the endogenous cell cycle inhibitor, p27. Our findings warrant clinical evaluation of PIM kinase inhibitors in patients with TN tumors that exhibit elevated MYC expression. PMID:27775705

PIM1 kinase inhibition as a targeted therapy against triple-negative breast tumors with elevated MYC expression.

PubMed

Horiuchi, Dai; Camarda, Roman; Zhou, Alicia Y; Yau, Christina; Momcilovic, Olga; Balakrishnan, Sanjeev; Corella, Alexandra N; Eyob, Henok; Kessenbrock, Kai; Lawson, Devon A; Marsh, Lindsey A; Anderton, Brittany N; Rohrberg, Julia; Kunder, Ratika; Bazarov, Alexey V; Yaswen, Paul; McManus, Michael T; Rugo, Hope S; Werb, Zena; Goga, Andrei

2016-11-01

Triple-negative breast cancer (TNBC), in which cells lack expression of the estrogen receptor (ER), the progesterone receptor (PR) and the ERBB2 (also known as HER2) receptor, is the breast cancer subtype with the poorest outcome. No targeted therapy is available against this subtype of cancer owing to a lack of validated molecular targets. We previously reported that signaling involving MYC-an essential, pleiotropic transcription factor that regulates the expression of hundreds of genes-is disproportionally higher in triple-negative (TN) tumors than in receptor-positive (RP) tumors. Direct inhibition of the oncogenic transcriptional activity of MYC has been challenging to achieve. Here, by conducting a shRNA screen targeting the kinome, we identified PIM1, a non-essential serine-threonine kinase, in a synthetic lethal interaction with MYC. PIM1 expression was higher in TN tumors than in RP tumors and was associated with poor prognosis in patients with hormone- and HER2-negative tumors. Small-molecule PIM kinase inhibitors halted the growth of human TN tumors with elevated MYC expression in patient-derived tumor xenograft (PDX) and MYC-driven transgenic mouse models of breast cancer by inhibiting the oncogenic transcriptional activity of MYC and restoring the function of the endogenous cell cycle inhibitor, p27. Our findings warrant clinical evaluation of PIM kinase inhibitors in patients with TN tumors that have elevated MYC expression.

Marker Protein Expression Combined With Expression Heterogeneity is a Powerful Indicator of Malignancy in Acral Lentiginous Melanomas.

PubMed

Cintra Lopes Carapeto, Fernando; Neves Comodo, Andréia; Germano, Andressa; Pereira Guimarães, Daiane; Barcelos, Denise; Fernandes, Mariana; Landman, Gilles

2017-02-01

Samples of acral lentiginous melanomas (ALMs) were obtained from the Department of Pathology at Escola Paulista de Medicina-Universidade Federal de São Paulo (UNIFESP), São Paulo, Brazil. Demographic, clinical, and follow-up data were obtained from the charts of Hospital São Paulo. From 2 tissue microarrays containing 60 nevi and quadruplicate samples of ≥1.0-mm of 49 ALM, sections were stained to evaluate SCF, KIT, BRAF, CYCLIND1, MYC, and PTEN immunohistochemical protein expression. Nevi and ALM from 2006 to 2010 were reviewed and collected. All specimens were in the vertical growth phase, and histopathological parameters indicated that tumors were at an advanced stage at diagnosis. Average tumor thickness was 6.95 mm, 63% were ulcerated, average mitotic index was 5 mitotic cells per mm, and 43% were at Clark's level V. Compared with nevi, the χ test showed that ALM significantly correlated with SCF protein expression (P = 0.001) and expression heterogeneity (P < 0.000). Similar findings were observed for KIT (P = 0.005, P = 0.003, respectively), MYC (P < 0.000, P < 0.000), and PTEN (P = 0.005, P < 0.000). Malignancy did not correlate with BRAF and CYCLIN D1 expression (P = 0.053 and P = 0.259, respectively), but it did significantly correlate with their heterogeneous expression (P < 0.000, P = 0.024, respectively). Combined protein expression had an odds ratio of greater malignancy when BRAF and MYC were positive and/or heterogeneously expressed (OR of 78 and 95, respectively). We show that marker protein expression, when combined with heterogeneous expression as shown by immunohistochemistry, is a powerful indicator of malignancy in ALMs, especially, when protein pairs are combined.

Inverse Relationship between Progesterone Receptor and Myc in Endometrial Cancer

PubMed Central

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

2016-01-01

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

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

A feedback loop comprising PRMT7 and miR-24-2 interplays with Oct4, Nanog, Klf4 and c-Myc to regulate stemness

PubMed Central

Lee, Sung-Hun; Chen, Tsai-Yu; Dhar, Shilpa S.; Gu, Bingnan; Chen, Kaifu; Kim, Young Zoon; Li, Wei; Lee, Min Gyu

2016-01-01

Self-renewal and pluripotency are two fundamental characteristics of embryonic stem cells (ESCs) and are controlled by diverse regulatory factors, including pluripotent factors, epigenetic regulators and microRNAs (miRNAs). Although histone methyltransferases are key epigenetic regulators, whether and how a histone methyltransferase forms a network with miRNAs and the core pluripotent factor system to regulate ESC stemness is little known. Here, we show that the protein arginine methyltransferase 7 (PRMT7) is a pluripotent factor essential for the stemness of mouse ESCs. PRMT7 repressed the miR-24-2 gene encoding miR-24-3p and miR-24-2-5p by upregulating the levels of symmetrically dimethylated H4R3. Notably, miR-24-3p targeted the 3′ untranslated regions (UTRs) of the major pluripotent factors Oct4, Nanog, Klf4 and c-Myc, whereas miR-24-2-5p silenced Klf4 and c-Myc expression. miR-24-3p and miR-24-2-5p also targeted the 3′UTR of their repressor gene Prmt7. miR-24-3p and miR-24-2-5p induced mouse ESC differentiation, and their anti-sense inhibitors substantially reversed spontaneous differentiation of PRMT7-depleted mouse ESCs. Oct4, Nanog, Klf4 and c-Myc positively regulated Prmt7 expression. These findings define miR-24-3p and miR-24-2-5p as new anti-pluripotent miRNAs and also reveal a novel epigenetic stemness-regulatory mechanism in which a double-negative feedback loop consisting of PRMT7 and miR-24-3p/miR24-2-5p interplays with Oct4, Nanog, Klf4 and c-Myc to control ESC stemness. PMID:27625395

A feedback loop comprising PRMT7 and miR-24-2 interplays with Oct4, Nanog, Klf4 and c-Myc to regulate stemness.

PubMed

Lee, Sung-Hun; Chen, Tsai-Yu; Dhar, Shilpa S; Gu, Bingnan; Chen, Kaifu; Kim, Young Zoon; Li, Wei; Lee, Min Gyu

2016-12-15

Self-renewal and pluripotency are two fundamental characteristics of embryonic stem cells (ESCs) and are controlled by diverse regulatory factors, including pluripotent factors, epigenetic regulators and microRNAs (miRNAs). Although histone methyltransferases are key epigenetic regulators, whether and how a histone methyltransferase forms a network with miRNAs and the core pluripotent factor system to regulate ESC stemness is little known. Here, we show that the protein arginine methyltransferase 7 (PRMT7) is a pluripotent factor essential for the stemness of mouse ESCs. PRMT7 repressed the miR-24-2 gene encoding miR-24-3p and miR-24-2-5p by upregulating the levels of symmetrically dimethylated H4R3. Notably, miR-24-3p targeted the 3' untranslated regions (UTRs) of the major pluripotent factors Oct4, Nanog, Klf4 and c-Myc, whereas miR-24-2-5p silenced Klf4 and c-Myc expression. miR-24-3p and miR-24-2-5p also targeted the 3'UTR of their repressor gene Prmt7 miR-24-3p and miR-24-2-5p induced mouse ESC differentiation, and their anti-sense inhibitors substantially reversed spontaneous differentiation of PRMT7-depleted mouse ESCs. Oct4, Nanog, Klf4 and c-Myc positively regulated Prmt7 expression. These findings define miR-24-3p and miR-24-2-5p as new anti-pluripotent miRNAs and also reveal a novel epigenetic stemness-regulatory mechanism in which a double-negative feedback loop consisting of PRMT7 and miR-24-3p/miR24-2-5p interplays with Oct4, Nanog, Klf4 and c-Myc to control ESC stemness. © The Author(s) 2016. Published by Oxford University Press on behalf of Nucleic Acids Research.

p53 and c-myc activation by Pasteurella haemolytica leukotoxin is correlated with bovine mononuclear cells apoptosis.

PubMed

Marcatili, A; D'Isanto, M; Vitiello, M; Galdiero, R; Galdiero, M

2002-04-01

To analyse the role of Pasteurella haemolytica Leukotoxin (LKT) in the mechanism of apoptotic cell death of bovine lymphocytes, we evaluated DNA fragmentation and p53 and c-myc expression. P. haemolytica strain ATCC 14003 was cultivated for LKT production. DNA fragmentation was analysed by electrophoresis on Agarose gel. DNA strand breaks in individual apoptotic cells were also detected by an in situ Terminal deoxy nucleotidyl Transferase (TdT). The Polymerase Chain Reaction (PCR) procedure was used for verified p53 and c-myc activation by P. haemolytica LKT. LKT was able to induce DNA fragmentation in a dose and time-dependent fashion. The greatest apoptotic effect was obtained using LKT at a concentration of 0.25 U. The results show that p53 and c-myc activation by LKT is correlated with apoptosis of bovine lymphocytes and monocytes. Our data suggest that LKT may have an important role in the bacterial virulence of Pasteurella haemolytica.

Myc-nick: a cytoplasmic cleavage product of Myc that promotes alpha-tubulin acetylation and cell differentiation.

PubMed

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

2010-08-06

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 alpha-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 alpha-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. Copyright 2010 Elsevier Inc. All rights reserved.

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

NASA Astrophysics Data System (ADS)

Kang, Hyun-Jin; Park, Hyun-Ju

2015-04-01

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

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

The Dysregulation of Polyamine Metabolism in Colorectal Cancer Is Associated with Overexpression of c-Myc and C/EBPβ rather than Enterotoxigenic Bacteroides fragilis Infection.

PubMed

Snezhkina, Anastasiya V; Krasnov, George S; Lipatova, Anastasiya V; Sadritdinova, Asiya F; Kardymon, Olga L; Fedorova, Maria S; Melnikova, Nataliya V; Stepanov, Oleg A; Zaretsky, Andrew R; Kaprin, Andrey D; Alekseev, Boris Y; Dmitriev, Alexey A; Kudryavtseva, Anna V

2016-01-01

Colorectal cancer is one of the most common cancers in the world. It is well known that the chronic inflammation can promote the progression of colorectal cancer (CRC). Recently, a number of studies revealed a potential association between colorectal inflammation, cancer progression, and infection caused by enterotoxigenic Bacteroides fragilis (ETBF). Bacterial enterotoxin activates spermine oxidase (SMO), which produces spermidine and H2O2 as byproducts of polyamine catabolism, which, in turn, enhances inflammation and tissue injury. Using qPCR analysis, we estimated the expression of SMOX gene and ETBF colonization in CRC patients. We found no statistically significant associations between them. Then we selected genes involved in polyamine metabolism, metabolic reprogramming, and inflammation regulation and estimated their expression in CRC. We observed overexpression of SMOX, ODC1, SRM, SMS, MTAP, c-Myc, C/EBPβ (CREBP), and other genes. We found that two mediators of metabolic reprogramming, inflammation, and cell proliferation c-Myc and C/EBPβ may serve as regulators of polyamine metabolism genes (SMOX, AZIN1, MTAP, SRM, ODC1, AMD1, and AGMAT) as they are overexpressed in tumors, have binding site according to ENCODE ChIP-Seq data, and demonstrate strong coexpression with their targets. Thus, increased polyamine metabolism in CRC could be driven by c-Myc and C/EBPβ rather than ETBF infection.

The Dysregulation of Polyamine Metabolism in Colorectal Cancer Is Associated with Overexpression of c-Myc and C/EBPβ rather than Enterotoxigenic Bacteroides fragilis Infection

PubMed Central

Snezhkina, Anastasiya V.; Lipatova, Anastasiya V.; Sadritdinova, Asiya F.; Kardymon, Olga L.; Fedorova, Maria S.; Kaprin, Andrey D.

2016-01-01

Colorectal cancer is one of the most common cancers in the world. It is well known that the chronic inflammation can promote the progression of colorectal cancer (CRC). Recently, a number of studies revealed a potential association between colorectal inflammation, cancer progression, and infection caused by enterotoxigenic Bacteroides fragilis (ETBF). Bacterial enterotoxin activates spermine oxidase (SMO), which produces spermidine and H2O2 as byproducts of polyamine catabolism, which, in turn, enhances inflammation and tissue injury. Using qPCR analysis, we estimated the expression of SMOX gene and ETBF colonization in CRC patients. We found no statistically significant associations between them. Then we selected genes involved in polyamine metabolism, metabolic reprogramming, and inflammation regulation and estimated their expression in CRC. We observed overexpression of SMOX, ODC1, SRM, SMS, MTAP, c-Myc, C/EBPβ (CREBP), and other genes. We found that two mediators of metabolic reprogramming, inflammation, and cell proliferation c-Myc and C/EBPβ may serve as regulators of polyamine metabolism genes (SMOX, AZIN1, MTAP, SRM, ODC1, AMD1, and AGMAT) as they are overexpressed in tumors, have binding site according to ENCODE ChIP-Seq data, and demonstrate strong coexpression with their targets. Thus, increased polyamine metabolism in CRC could be driven by c-Myc and C/EBPβ rather than ETBF infection. PMID:27433286

Developmental Regulation of Mitochondrial Apoptosis by c-Myc Governs Age- and Tissue-Specific Sensitivity to Cancer Therapeutics.

PubMed

Sarosiek, Kristopher A; Fraser, Cameron; Muthalagu, Nathiya; Bhola, Patrick D; Chang, Weiting; McBrayer, Samuel K; Cantlon, Adam; Fisch, Sudeshna; Golomb-Mello, Gail; Ryan, Jeremy A; Deng, Jing; Jian, Brian; Corbett, Chris; Goldenberg, Marti; Madsen, Joseph R; Liao, Ronglih; Walsh, Dominic; Sedivy, John; Murphy, Daniel J; Carrasco, Daniel Ruben; Robinson, Shenandoah; Moslehi, Javid; Letai, Anthony

2017-01-09

It is not understood why healthy tissues can exhibit varying levels of sensitivity to the same toxic stimuli. Using BH3 profiling, we find that mitochondria of many adult somatic tissues, including brain, heart, and kidneys, are profoundly refractory to pro-apoptotic signaling, leading to cellular resistance to cytotoxic chemotherapies and ionizing radiation. In contrast, mitochondria from these tissues in young mice and humans are primed for apoptosis, predisposing them to undergo cell death in response to genotoxic damage. While expression of the apoptotic protein machinery is nearly absent by adulthood, in young tissues its expression is driven by c-Myc, linking developmental growth to cell death. These differences may explain why pediatric cancer patients have a higher risk of developing treatment-associated toxicities. Copyright © 2017 Elsevier Inc. All rights reserved.

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

Drosophila Myc is oncogenic in mammalian cells and plays a role in the diminutive phenotype

PubMed Central

Schreiber-Agus, Nicole; Stein, David; Chen, Ken; Goltz, Jason S.; Stevens, Leslie; DePinho, Ronald A.

1997-01-01

Biochemical and biological activities of Myc oncoproteins are highly dependent upon their association with another basic region helix–loop–helix/leucine zipper (bHLH/LZ) protein, Max. Our previous observation that the DNA-binding/dimerization region of Max is absolutely conserved throughout vertebrate evolution provided the basis for a yeast two-hybrid interaction screen that led to the isolation of the Drosophila Myc (dMyc1) protein. Structural conservation in regions of known functional significance is consistent with the ability of dMyc1 to interact with vertebrate Max, to transactivate gene expression in yeast cells, and to cooperate with activated H-RAS to effect the malignant transformation of primary mammalian cells. The ability of P-element-mediated ectopic expression of dmyc1 to reverse a subset of the phenotypic alterations associated with the diminutive mutation suggests that diminutive may correspond to dmyc1. This finding, along with the localization of dmyc1 expression to zones of high proliferative activity in the embryo, implicates dMyc1 as an integral regulator of Drosophila growth and development. PMID:9037036

Quantum dots (QDs) restrain human cervical carcinoma HeLa cell proliferation through inhibition of the ROCK-c-Myc signaling.

PubMed

Chen, Liqun; Qu, Guangbo; Zhang, Changwen; Zhang, Shuping; He, Jiuyang; Sang, Nan; Liu, Sijin

2013-03-01

Cancers often cause significant morbidity and even death to patients. To date, conventional therapies, such as chemotherapy, radiation and surgery, are often limited; meanwhile, novel anticancer therapeutics are urgently needed to improve clinical treatments. Rapid application of nanotechnology and nanomaterials represents a promising vista for the development of anti-cancer therapeutics. However, how to integrate the novel properties of nanotechnology and nanomaterials into cancer treatment warrants close investigation. In the current study, we report a novel finding about the inhibitory effect of CdSe quantum dots (QDs) on Rho-associated kinase (ROCK) activity in cervical carcinoma HeLa cells associated with the attenuation of the ROCK-c-Myc signaling. We mechanistically demonstrated that QD-conducted ROCK inhibition greatly diminished c-Myc protein stability due to reduced phosphorylation, and also suppressed its activity in transcribing target genes (e.g. HSPC111). Thus, the treatment of QDs greatly restrained HeLa cell growth by inducing cell cycle arrest at G1 phase due to the reduced ability of c-Myc in driving cell proliferation. Additionally, since HSPC111, one of the c-Myc targets, is involved in regulating cell growth through ribosomal biogenesis and assembly, the downregulation of HSPC111 could also contribute to diminished proliferation in HeLa cells upon QD treatment. These results together suggested that inhibition of ROCK activity or ROCK-mediated c-Myc signaling in tumor cells upon QD treatment might represent a promising strategy to restrain tumor progression for human cervical carcinoma.

Overexpression of SLC34A2 is an independent prognostic indicator in bladder cancer and its depletion suppresses tumor growth via decreasing c-Myc expression and transcriptional activity

PubMed Central

Ye, Wen; Chen, Cui; Gao, Ying; Zheng, Zou-Shan; Xu, Yi; Yun, Miao; Weng, Hui-Wen; Xie, Dan; Ye, Sheng; Zhang, Jia-Xing

2017-01-01

Solute carrier family 34 member 2 (SLC34A2), a pH-sensitive sodium-dependent phosphate transporter, is associated with several human cancers. In this study, we investigate the clinical significance of SLC34A2 and its function in human bladder cancer (BC). The expression dynamics of SLC34A2 were examined in two independent cohorts of BC samples by quantitative PCR, western blotting and immunohistochemical staining. In the training cohort (156 cases), we applied the X-tile program software to assess the optimal cutoff points for biomarkers in order to accurately classify patients according to clinical outcome. In the validation cohort (130 cases), the cutoff score derived from X-title analysis was investigated to determine the association of SLC34A2 expression with survival outcome. A series of in vitro and in vivo assays were then performed to elucidate the function of SLC34A2 in BC and its underlying mechanisms. Results showed that SLC34A2 was significantly upregulated in BC cell lines and clinical samples. In both two cohorts of BC samples, high expression of SLC34A2 was associated with large tumor size, advanced T status and poor patients' survival. The depletion of SLC34A2 in BC suppressed cellular viability, colony formation and anchorage-independent growth in vitro, and inhibited xenograft tumor growth in vivo, whereas overexpression of SLC34A2 had the converse effect. Simultaneously, downregulation of SLC34A2 decreased the transcriptional activity and protein expression level of c-Myc in BC cells, whereas restoration of c-Myc expression could compromise the anti-proliferation effect of SLC34A2 depletion. Furthermore, miR-214 was proved as a negative regulator of SLC34A2. Our present study illustrated that SLC34A2 has an important role in promoting proliferation and tumorigenicity of BC, and may represent a novel therapeutic target for this disease. PMID:28151475

Copper/MYC/CTR1 interplay: a dangerous relationship in hepatocellular carcinoma

PubMed Central

Barbaro, Barbara; Illi, Barbara; Nasi, Sergio; Martini, Maurizio; Licata, Anna; Miele, Luca; Grieco, Antonio; Balsano, Clara

2018-01-01

Free serum copper correlates with tumor incidence and progression of human cancers, including hepatocellular carcinoma (HCC). Copper extracellular uptake is provided by the transporter CTR1, whose expression is regulated to avoid excessive intracellular copper entry. Inadequate copper serum concentration is involved in the pathogenesis of Non Alcoholic Fatty Liver Disease (NAFLD), which is becoming a major cause of liver damage progression and HCC incidence. Finally, MYC is over-expressed in most of HCCs and is a critical regulator of cellular growth, tumor invasion and metastasis. The purpose of our study was to understand if higher serum copper concentrations might be involved in the progression of NAFLD-cirrhosis toward-HCC. We investigated whether high exogenous copper levels sensitize liver cells to transformation and if it exists an interplay between copper-related proteins and MYC oncogene. NAFLD-cirrhotic patients were characterized by a statistical significant enhancement of serum copper levels, even more evident in HCC patients. We demonstrated that high extracellular copper concentrations increase cell growth, migration, and invasion of liver cancer cells by modulating MYC/CTR1 axis. We highlighted that MYC binds a specific region of the CTR1 promoter, regulating its transcription. Accordingly, CTR1 and MYC proteins expression were progressively up-regulated in liver tissues from NAFLD-cirrhotic to HCC patients. This work provides novel insights on the molecular mechanisms by which copper may favor the progression from cirrhosis to cancer. The Cu/MYC/CTR1 interplay opens a window to refine HCC diagnosis and design new combined therapies. PMID:29507693

Copper/MYC/CTR1 interplay: a dangerous relationship in hepatocellular carcinoma.

PubMed

Porcu, Cristiana; Antonucci, Laura; Barbaro, Barbara; Illi, Barbara; Nasi, Sergio; Martini, Maurizio; Licata, Anna; Miele, Luca; Grieco, Antonio; Balsano, Clara

2018-02-06

Free serum copper correlates with tumor incidence and progression of human cancers, including hepatocellular carcinoma (HCC). Copper extracellular uptake is provided by the transporter CTR1, whose expression is regulated to avoid excessive intracellular copper entry. Inadequate copper serum concentration is involved in the pathogenesis of Non Alcoholic Fatty Liver Disease (NAFLD), which is becoming a major cause of liver damage progression and HCC incidence. Finally, MYC is over-expressed in most of HCCs and is a critical regulator of cellular growth, tumor invasion and metastasis. The purpose of our study was to understand if higher serum copper concentrations might be involved in the progression of NAFLD-cirrhosis toward-HCC. We investigated whether high exogenous copper levels sensitize liver cells to transformation and if it exists an interplay between copper-related proteins and MYC oncogene. NAFLD-cirrhotic patients were characterized by a statistical significant enhancement of serum copper levels, even more evident in HCC patients. We demonstrated that high extracellular copper concentrations increase cell growth, migration, and invasion of liver cancer cells by modulating MYC/CTR1 axis. We highlighted that MYC binds a specific region of the CTR1 promoter, regulating its transcription. Accordingly, CTR1 and MYC proteins expression were progressively up-regulated in liver tissues from NAFLD-cirrhotic to HCC patients. This work provides novel insights on the molecular mechanisms by which copper may favor the progression from cirrhosis to cancer. The Cu/MYC/CTR1 interplay opens a window to refine HCC diagnosis and design new combined therapies.

Expression Analysis of p16, c-Myc, and mSin3A in Non-small Cell Lung Cancer by Computer Aided Scoring and Analysis (CASA).

PubMed

Salmaninejad, Arash; Estiar, Mehrdad Asghari; Gill, Rajbir K; Shih, Joanna H; Hewitt, Stephen; Jeon, Hyo-Sung; Fukuoka, Junya; Shilo, Konstantin; Shakoori, Abbas; Jen, Jin

2015-01-01

Immunohistochemical analysis (IHC) of tissue microarray (TMA) slides enables large sets of tissue samples to be analyzed simultaneously on a single slide. However, manual evaluation of small cores on a TMA slide is time consuming and error prone. We describe a computer aided scoring and analysis (CASA) method to allow facile and reliable scoring of IHC staining using TMA containing 300 non-small cell lung cancer (NSCLC) cases. In the two previous published papers utilizing our TMA slides of lung cancer we examined 18 proteins involved in the chromatin machinery. We developed our study using more proteins of the chromatin complex and several transcription factors that facilitate the chromatin machinery. Then, a total of 78 antibodies were evaluated by CASA to derive a normalized intensity value that correlated with the overall staining status of the targeting protein. The intensity values for TMA cores were then examined for association to clinical variables and predictive significance individually and with other factors. RESULTs: Using our TMA, the intensity of several protein pairs were significantly correlated with an increased risk of death in NSCLC. These included c-Myc with p16, mSin3A with p16 and c-Myc with mSinA. Predictive values of these pairs remained significant when evaluated based on standard IHC scores. Our results demonstrate the usefulness of CASA as a valuable tool for systematic assessment of TMA slides to identify potential predictive biomarkers using a large set of primary human tissues.

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.

Cooperative action of multiple cis-acting elements is required for N-myc expression in branchial arches: specific contribution of GATA3.

PubMed

Potvin, Eric; Beuret, Laurent; Cadrin-Girard, Jean-François; Carter, Marcelle; Roy, Sophie; Tremblay, Michel; Charron, Jean

2010-11-01

The precise expression of the N-myc proto-oncogene is essential for normal mammalian development, whereas altered N-myc gene regulation is known to be a determinant factor in tumor formation. Using transgenic mouse embryos, we show that N-myc sequences from kb -8.7 to kb +7.2 are sufficient to reproduce the N-myc embryonic expression profile in developing branchial arches and limb buds. These sequences encompass several regulatory elements dispersed throughout the N-myc locus, including an upstream limb bud enhancer, a downstream somite enhancer, a branchial arch enhancer in the second intron, and a negative regulatory element in the first intron. N-myc expression in the limb buds is under the dominant control of the limb bud enhancer. The expression in the branchial arches necessitates the interplay of three regulatory domains. The branchial arch enhancer cooperates with the somite enhancer region to prevent an inhibitory activity contained in the first intron. The characterization of the branchial arch enhancer has revealed a specific role of the transcription factor GATA3 in the regulation of N-myc expression. Together, these data demonstrate that correct N-myc developmental expression is achieved via cooperation of multiple positive and negative regulatory elements.

MYC interaction with the tumor suppressive SWI/SNF complex member INI1 regulates transcription and cellular transformation

PubMed Central

Stojanova, Angelina; Tu, William B.; Ponzielli, Romina; Kotlyar, Max; Chan, Pak-Kei; Boutros, Paul C.; Khosravi, Fereshteh; Jurisica, Igor; Raught, Brian; Penn, Linda Z.

2016-01-01

ABSTRACT MYC is a key driver of cellular transformation and is deregulated in most human cancers. Studies of MYC and its interactors have provided mechanistic insight into its role as a regulator of gene transcription. MYC has been previously linked to chromatin regulation through its interaction with INI1 (SMARCB1/hSNF5/BAF47), a core member of the SWI/SNF chromatin remodeling complex. INI1 is a potent tumor suppressor that is inactivated in several types of cancers, most prominently as the hallmark alteration in pediatric malignant rhabdoid tumors. However, the molecular and functional interaction of MYC and INI1 remains unclear. Here, we characterize the MYC-INI1 interaction in mammalian cells, mapping their minimal binding domains to functionally significant regions of MYC (leucine zipper) and INI1 (repeat motifs), and demonstrating that the interaction does not interfere with MYC-MAX interaction. Protein-protein interaction network analysis expands the MYC-INI1 interaction to the SWI/SNF complex and a larger network of chromatin regulatory complexes. Genome-wide analysis reveals that the DNA-binding regions and target genes of INI1 significantly overlap with those of MYC. In an INI1-deficient rhabdoid tumor system, we observe that with re-expression of INI1, MYC and INI1 bind to common target genes and have opposing effects on gene expression. Functionally, INI1 re-expression suppresses cell proliferation and MYC-potentiated transformation. Our findings thus establish the antagonistic roles of the INI1 and MYC transcriptional regulators in mediating cellular and oncogenic functions. PMID:27267444

Zap70 functions to maintain stemness of mouse embryonic stem cells by negatively regulating Jak1/Stat3/c-Myc signaling

PubMed Central

Cha, Young; Moon, Bo-Hyun; Lee, Mi-Ok; Ahn, Hee-Jin; Lee, Hye-Jin; Lee, Kyung-Ah; Fornace, Albert J.; Kim, Kwang-Soo; Cha, Hyuk-Jin; Park, Kyung-Soon

2011-01-01

Zeta-chain associated protein kinase-70 (Zap70), a Syk family tyrosine kinase, has been reported to be present exclusively in normal T cells, Natural Killer (NK) cells, and B cells, serving as a pivotal regulator of antigen-mediated receptor signaling and development. In this study, we report that Zap70 is expressed in undifferentiated mouse embryonic stem cells (mESCs) and may critically regulate self-renewal and pluripotency in mESCs. We found that Zap70 knocked-down mESCs (Zap70KD) show sustained self-renewal and defective differentiation. In addition, we present evidence that the sustained self-renewal in Zap70KD is associated with enhanced Jak/Stat3 signaling and c-Myc induction. These altered signaling appears to result from up-regulated LIFR and down-regulated SHP-1 phosphatase activity. Based on these results, we propose that, in undifferentiated mESCs, Zap70 plays important roles in modulating the balance between self-renewal capacity and pluripotent differentiation ability as a key regulator of the Jak/Stat3/c-Myc signaling pathway. PMID:20641039

Proteomic Characterization of the World Trade Center dust-activated mdig and c-myc signaling circuit linked to multiple myeloma

PubMed Central

Wu, Kai; Li, Lingzhi; Thakur, Chitra; Lu, Yongju; Zhang, Xiangmin; Yi, Zhengping; Chen, Fei

2016-01-01

Several epidemiological studies suggested an increased incidence rate of multiple myeloma (MM) among first responders and other individuals who exposed to World Trade Center (WTC) dust. In this report, we provided evidence showing that WTC dust is potent in inducing mdig protein and/or mRNA in bronchial epithelial cells, B cells and MM cell lines. An increased mdig expression in MM bone marrow was observed, which is associated with the disease progression and prognosis of the MM patients. Through integrative genomics and proteomics approaches, we further demonstrated that mdig directly interacts with c-myc and JAK1 in MM cell lines, which contributes to hyperactivation of the IL-6-JAK-STAT3 signaling important for the pathogenesis of MM. Genetic silencing of mdig reduced activity of the major downstream effectors in the IL-6-JAK-STAT3 pathway. Taken together, these data suggest that WTC dust may be one of the key etiological factors for those who had been exposed for the development of MM by activating mdig and c-myc signaling circuit linked to the IL-6-JAK-STAT3 pathway essential for the tumorigenesis of the malignant plasma cells. PMID:27833099

LncRNA IDH1-AS1 links the functions of c-Myc and HIF1α via IDH1 to regulate the Warburg effect

PubMed Central

Xiang, Shaoxun; Gu, Hao; Thorne, Rick F.; Zhang, Xu Dong; Wu, Mian

2018-01-01

The oncoprotein c-Myc plays an important role in regulating glycolysis under normoxia; yet, in cancer cells, HIF1α, which is essential for driving glycolysis under hypoxia, is often up-regulated even in the presence of oxygen. The relationship between these two major regulators of the Warburg effect remains to be fully defined. Here we demonstrate that regulation of a long noncoding RNA (lncRNA), named IDH1-AS1, enables c-Myc to collaborate with HIF1α in activating the Warburg effect under normoxia. c-Myc transcriptionally repressed IDH1-AS1, which, upon expression, promoted homodimerization of IDH1 and thus enhanced its enzymatic activity. This resulted in increased α-KG and decreased ROS production and subsequent HIF1α down-regulation, leading to attenuation of glycolysis. Hence, c-Myc repression of IDH1-AS1 promotes activation of the Warburg effect by HIF1α. As such, IDH1-AS1 overexpression inhibited cell proliferation, whereas silencing of IDH1-AS1 promoted cell proliferation and cancer xenograft growth. Restoring IDH1-AS1 expression may therefore represent a potential metabolic approach for cancer treatment. PMID:29378948

Carbazole ligands as c-myc G-quadruplex binders.

PubMed

Głuszyńska, Agata; Juskowiak, Bernard; Kuta-Siejkowska, Martyna; Hoffmann, Marcin; Haider, Shozeb

2018-07-15

The interactions of c-myc G-quadruplex with three carbazole derivatives were investigated by UV-Vis spectrophotometry, fluorescence, CD spectroscopy, and molecular modeling. The results showed that a combination of carbazole scaffold functionalized with ethyl, triazole and imidazole groups resulted in stabilization of the intramolecular G-quadruplex formed by the DNA sequence derived from the NHE III 1 region of c-myc oncogene (Pu22). Binding to the G-quadruplex Pu22 resulted in the significant increase in fluorescence intensity of complexed ligands 1-3. All ligands were capable of interacting with G4 DNA with binding stoichiometry indicating that two ligand molecules bind to G-quadruplex with comparable affinity, which agrees with binding model of end-stacking on terminal G-tetrads. Copyright © 2018 Elsevier B.V. All rights reserved.

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

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

PubMed

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-Outschoorn, 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

2016-11-08

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.

MicroRNA-26a is a key regulon that inhibits progression and metastasis of c-Myc/EZH2 double high advanced hepatocellular carcinoma.

PubMed

Zhang, Xiang; Zhang, Xiao; Wang, Ting; Wang, Lei; Tan, Zhijun; Wei, Wei; Yan, Bo; Zhao, Jing; Wu, Kaichun; Yang, Angang; Zhang, Rui; Jia, Lintao

2018-07-10

The transcription factor c-Myc is a key driver for hepatocellular carcinomas (HCCs), while the polycombrepressive complex 2 (PRC2) subunit EZH2 is an essential biomarker of HCC. c-Myc epigenetically silences tumor suppressors by recruiting PRC2 and inducing methylation of histone H3 lysine 27. However, it remains elusive how they are regulated in HCC. We found here that microRNA-26a (miR-26a) suppresses c-Myc, a classical Wnt pathway target gene, by targeting the Wnt pathway coactivator, cyclin-dependent kinase 8 (CDK8); miR-26a also directly targets and inhibits EZH2. The expression of MIR26A2, a predominant origin of miR-26a transcripts in hepatic cells, is repressed by c-Myc/PRC2, thereby forming a c-Myc/miR-26a/CDK8 regulatory circuit in HCC. Meanwhile, miR-26a suppresses migration of HCC by targeting p21-activated kinase 2 (PAK2), a critical kinase linking Rho GTPases to cytoskeleton reorganization. Consequently, in vivo delivery of miR-26a remarkably suppressed the development of xenograft HCC and metastasis of orthotopic HCC by downregulating c-Myc, CDK8 and PAK2. These findings unraveled a novel mechanism of c-Myc and Wnt/β-catenin interplay that dictates HCC pathogenesis, and have implications for the potential applicability of miRNA delivery in targeting the newly identified signaling axis and treating metastatic HCCs. Copyright © 2018 Elsevier B.V. All rights reserved.

Analysis of protein function in clinical C. albicans isolates

PubMed Central

Gerami-Nejad, Maryam; Forche, Anja; McClellan, Mark; Berman, Judith

2012-01-01

Clinical isolates are prototrophic and hence are not amenable to genetic manipulation using nutritional markers. Here we describe a new set of plasmids carrying the NAT1 (nourseothricin) drug resistance marker (Shen et al., 2005) that can be used both in clinical isolates and in laboratory strains. We constructed novel plasmids containing HA-NAT1 or MYC-NAT1 cassettes to facilitate PCR-mediated construction of strains with C-terminal epitope-tagged proteins and a NAT1-pMet3-GFP plasmid to enable conditional expression of proteins with or without the green fluorescent protein fused at the N-terminus. Furthermore, for proteins that require both the endogenous N- and C-termini for function, we have constructed a GF-NAT1-FP cassette carrying truncated alleles that facilitate insertion of an intact, single copy of GFP internal to the coding sequence. In addition, GFP-NAT1, RFP-NAT1, and M-Cherry-NAT1 plasmids were constructed expressing two differently labeled gene products for the study of protein co-expression and co-localization in vivo. Together, these vectors provide a useful set of genetic tools for studying diverse aspects of gene function in C. albicans clinical as well as laboratory strains. PMID:22777821

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

PubMed Central

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

2017-01-01

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. PMID:28119527

Virulence Factors of Geminivirus Interact with MYC2 to Subvert Plant Resistance and Promote Vector Performance[C][W

PubMed Central

Li, Ran; Weldegergis, Berhane T.; Li, Jie; Jung, Choonkyun; Qu, Jing; Sun, Yanwei; Qian, Hongmei; Tee, ChuanSia; van Loon, Joop J.A.; Dicke, Marcel; Chua, Nam-Hai; Liu, Shu-Sheng

2014-01-01

A pathogen may cause infected plants to promote the performance of its transmitting vector, which accelerates the spread of the pathogen. This positive effect of a pathogen on its vector via their shared host plant is termed indirect mutualism. For example, terpene biosynthesis is suppressed in begomovirus-infected plants, leading to reduced plant resistance and enhanced performance of the whiteflies (Bemisia tabaci) that transmit these viruses. Although begomovirus-whitefly mutualism has been known, the underlying mechanism is still elusive. Here, we identified βC1 of Tomato yellow leaf curl China virus, a monopartite begomovirus, as the viral genetic factor that suppresses plant terpene biosynthesis. βC1 directly interacts with the basic helix-loop-helix transcription factor MYC2 to compromise the activation of MYC2-regulated terpene synthase genes, thereby reducing whitefly resistance. MYC2 associates with the bipartite begomoviral protein BV1, suggesting that MYC2 is an evolutionarily conserved target of begomoviruses for the suppression of terpene-based resistance and the promotion of vector performance. Our findings describe how this viral pathogen regulates host plant metabolism to establish mutualism with its insect vector. PMID:25490915

MYC Immunohistochemistry to Identify MYC-Driven B-Cell Lymphomas in Clinical Practice.

PubMed

Kluk, Michael J; Ho, Caleb; Yu, Hongbo; Chen, Benjamin J; Neuberg, Donna S; Dal Cin, Paola; Woda, Bruce A; Pinkus, Geraldine S; Rodig, Scott J

2016-02-01

Immunohistochemistry with anti-MYC antibody (MYC IHC) detects MYC protein in fixed samples of aggressive B-cell lymphomas and, according to the number of positive staining tumor nuclei, facilitates tumor subclassification, predicts underlying MYC rearrangements, and stratifies patient outcome. We aimed to determine the performance of MYC IHC in clinical practice. We reviewed MYC IHC performed on control specimens and 256 aggressive B-cell lymphomas and compared clinically reported IHC scores with experts' review. Control tissues showed less than 5% variation in daily IHC staining. Reported and expert IHC scores were well correlated (r = 0.86) with an SD of 14.2%. Reported IHC scores 30% or less and 70% or more were accurate (94.5%) compared with experts in categorizing tumors as "MYC IHC-Low" and "MYC IHC-High," respectively, but scores 40% to 60% were not (60.3%). The mean IHC score among lymphomas with MYC rearrangements was 80%, but with a large range of scores (20%-100%). There was no statistically significant association between IHC score and MYC copy number. Under optimal conditions, clinically reported MYC IHC scores are concordant with expert scores within 15%. MYC IHC does not capture all B-cell lymphomas with MYC rearrangements, however. MYC IHC and MYC fluorescence in situ hybridization are both recommended to identify MYC-driven B-cell lymphomas. © American Society for Clinical Pathology, 2016. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Melatonin promotes circadian rhythm-induced proliferation through Clock/histone deacetylase 3/c-Myc interaction in mouse adipose tissue.

PubMed

Liu, Zhenjiang; Gan, Lu; Luo, Dan; Sun, Chao

2017-05-01

Melatonin is synthesized in the pineal gland and controls circadian rhythm of peripheral adipose tissue, resulting in changes in body weight. Although core regulatory components of clock rhythmicity have been defined, insight into the mechanisms of circadian rhythm-mediated proliferation in adipose tissue is still limited. Here, we showed that melatonin (20 mg/kg/d) promoted circadian and proliferation processes in white adipose tissue. The circadian amplitudes of brain and muscle aryl hydrocarbon receptor nuclear translocator-like 1 (Bmal1, P<.05) and circadian locomotor output cycles kaput (Clock, P<.05), period 2 (Per2, P<.05), cyclin E (P<.05), and c-Myc (P<.05) were directly increased by melatonin in adipose tissue. Melatonin also promoted cell cycle and increased cell numbers (P<.05), which was correlated with the Clock expression (P<.05). Further analysis demonstrated that Clock bound to the E-box elements in the promoter region of c-Myc and then directly stimulated c-Myc transcription. Moreover, Clock physically interacted with histone deacetylase 3 (HDAC3) and formed a complex with c-Myc to promote adipocyte proliferation. Melatonin also attenuated circadian disruption and promoted adipocyte proliferation in chronic jet-lagged mice and obese mice. Thus, our study found that melatonin promoted adipocyte proliferation by forming a Clock/HDAC3/c-Myc complex and subsequently driving the circadian amplitudes of proliferation genes. Our data reveal a novel mechanism that links circadian rhythm to cell proliferation in adipose tissue. These findings also identify a new potential means for melatonin to prevent and treat sleep deprivation-caused obesity. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Redox regulation of cardiomyocyte cell cycling via an ERK1/2 and c-Myc-dependent activation of cyclin D2 transcription

PubMed Central

Murray, Thomas V.A.; Smyrnias, Ioannis; Schnelle, Moritz; Mistry, Rajesh K.; Zhang, Min; Beretta, Matteo; Martin, Daniel; Anilkumar, Narayana; de Silva, Shana M.; Shah, Ajay M.; Brewer, Alison C.

2015-01-01

Adult mammalian cardiomyocytes have a very limited capacity to proliferate, and consequently the loss of cells after cardiac stress promotes heart failure. Recent evidence suggests that administration of hydrogen peroxide (H2O2), can regulate redox-dependent signalling pathway(s) to promote cardiomyocyte proliferation in vitro, but the potential relevance of such a pathway in vivo has not been tested. We have generated a transgenic (Tg) mouse model in which the H2O2-generating enzyme, NADPH oxidase 4 (Nox4), is overexpressed within the postnatal cardiomyocytes, and observed that the hearts of 1–3 week old Tg mice pups are larger in comparison to wild type (Wt) littermate controls. We demonstrate that the cardiomyocytes of Tg mouse pups have increased cell cycling capacity in vivo as determined by incorporation of 5-bromo-2′-deoxyuridine. Further, microarray analyses of the transcriptome of these Tg mouse hearts suggested that the expression of cyclin D2 is significantly increased. We investigated the molecular mechanisms which underlie this more proliferative phenotype in isolated neonatal rat cardiomyocytes (NRCs) in vitro, and demonstrate that Nox4 overexpression mediates an H2O2-dependent activation of the ERK1/2 signalling pathway, which in turn phosphorylates and activates the transcription factor c-myc. This results in a significant increase in cyclin D2 expression, which we show to be mediated, at least in part, by cis-acting c-myc binding sites within the proximal cyclin D2 promoter. Overexpression of Nox4 in NRCs results in an increase in their proliferative capacity that is ablated by the silencing of cyclin D2. We further demonstrate activation of the ERK1/2 signalling pathway, increased phosphorylation of c-myc and significantly increased expression of cyclin D2 protein in the Nox4 Tg hearts. We suggest that this pathway acts to maintain the proliferative capacity of cardiomyocytes in Nox4 Tg pups in vivo and so delays their exit from the cell

Parp-1 genetic ablation in Ela-myc mice unveils novel roles for Parp-1 in pancreatic cancer.

PubMed

Martínez-Bosch, Neus; Iglesias, Mar; Munné-Collado, Jessica; Martínez-Cáceres, Carlos; Moreno, Mireia; Guerra, Carmen; Yélamos, Jose; Navarro, Pilar

2014-10-01

Pancreatic cancer has a dismal prognosis and is currently the fourth leading cause of cancer-related death in developed countries. The inhibition of poly(ADP-ribose) polymerase-1 (Parp-1), the major protein responsible for poly(ADP-ribosy)lation in response to DNA damage, has emerged as a promising treatment for several tumour types. Here we aimed to elucidate the involvement of Parp-1 in pancreatic tumour progression. We assessed Parp-1 protein expression in normal, preneoplastic and pancreatic tumour samples from humans and from K-Ras- and c-myc-driven mouse models of pancreatic cancer. Parp-1 was highly expressed in acinar cells in normal and cancer tissues. In contrast, ductal cells expressed very low or undetectable levels of this protein, both in a normal and in a tumour context. The Parp-1 expression pattern was similar in human and mouse samples, thereby validating the use of animal models for further studies. To determine the in vivo effects of Parp-1 depletion on pancreatic cancer progression, Ela-myc-driven pancreatic tumour development was analysed in a Parp-1 knock-out background. Loss of Parp-1 resulted in increased tumour necrosis and decreased proliferation, apoptosis and angiogenesis. Interestingly, Ela-myc:Parp-1(-/-) mice displayed fewer ductal tumours than their Ela-myc:Parp-1(+/+) counterparts, suggesting that Parp-1 participates in promoting acinar-to-ductal metaplasia, a key event in pancreatic cancer initiation. Moreover, impaired macrophage recruitment can be responsible for the ADM blockade found in the Ela-myc:Parp-1(-/-) mice. Finally, molecular analysis revealed that Parp-1 modulates ADM downstream of the Stat3-MMP7 axis and is also involved in transcriptional up-regulation of the MDM2, VEGFR1 and MMP28 cancer-related genes. In conclusion, the expression pattern of Parp-1 in normal and cancer tissue and the in vivo functional effects of Parp-1 depletion point to a novel role for this protein in pancreatic carcinogenesis and shed light

HPV positive neuroendocrine cervical cancer cells are dependent on Myc but not E6/E7 viral oncogenes.

PubMed

Yuan, Hang; Krawczyk, Ewa; Blancato, Jan; Albanese, Christopher; Zhou, Dan; Wang, Naidong; Paul, Siddartha; Alkhilaiwi, Faris; Palechor-Ceron, Nancy; Dakic, Aleksandra; Fang, Shuang; Choudhary, Sujata; Hou, Tung-Wei; Zheng, Yun-Ling; Haddad, Bassem R; Usuda, Yukari; Hartmann, Dan; Symer, David; Gillison, Maura; Agarwal, Seema; Wangsa, Danny; Ried, Thomas; Liu, Xuefeng; Schlegel, Richard

2017-04-05

Using conditional cell reprogramming, we generated a stable cell culture of an extremely rare and aggressive neuroendocrine cervical cancer. The cultured cells contained HPV-16, formed colonies in soft agar and rapidly produced tumors in immunodeficient mice. The HPV-16 genome was integrated adjacent to the Myc gene, both of which were amplified 40-fold. Analysis of RNA transcripts detected fusion of the HPV/Myc genes, arising from apparent microhomologous recombination. Spectral karyotyping (SKY) and fluorescent-in-situ hybridization (FISH) demonstrated coordinate localization and translocation of the amplified Myc and HPV genes on chromosomes 8 and 21. Similar to the primary tumor, tumor cell cultures expressed very high levels of the Myc protein and, in contrast to all other HPV-positive cervical cancer cell lines, they harbored a gain-of-function mutation in p53 (R273C). Unexpectedly, viral oncogene knockdown had no effect on the growth of the cells, but it did inhibit the proliferation of a conventional HPV-16 positive cervical cancer cell line. Knockdown of Myc, but not the mutant p53, significantly inhibited tumor cell proliferation. On the basis of these data, we propose that the primary driver of transformation in this aggressive cervical cancer is not HPV oncogene expression but rather the overexpression of Myc.

Pharmacological targeting of MYC-regulated IRE1/XBP1 pathway suppresses MYC-driven breast cancer.

PubMed

Zhao, Na; Cao, Jin; Xu, Longyong; Tang, Qianzi; Dobrolecki, Lacey E; Lv, Xiangdong; Talukdar, Manisha; Lu, Yang; Wang, Xiaoran; Hu, Dorothy Z; Shi, Qing; Xiang, Yu; Wang, Yunfei; Liu, Xia; Bu, Wen; Jiang, Yi; Li, Mingzhou; Gong, Yingyun; Sun, Zheng; Ying, Haoqiang; Yuan, Bo; Lin, Xia; Feng, Xin-Hua; Hartig, Sean M; Li, Feng; Shen, Haifa; Chen, Yiwen; Han, Leng; Zeng, Qingping; Patterson, John B; Kaipparettu, Benny Abraham; Putluri, Nagireddy; Sicheri, Frank; Rosen, Jeffrey M; Lewis, Michael T; Chen, Xi

2018-04-02

The unfolded protein response (UPR) is a cellular homeostatic mechanism that is activated in many human cancers and plays pivotal roles in tumor progression and therapy resistance. However, the molecular mechanisms for UPR activation and regulation in cancer cells remain elusive. Here, we show that oncogenic MYC regulates the inositol-requiring enzyme 1 (IRE1)/X-box binding protein 1 (XBP1) branch of the UPR in breast cancer via multiple mechanisms. We found that MYC directly controls IRE1 transcription by binding to its promoter and enhancer. Furthermore, MYC forms a transcriptional complex with XBP1, a target of IRE1, and enhances its transcriptional activity. Importantly, we demonstrate that XBP1 is a synthetic lethal partner of MYC. Silencing of XBP1 selectively blocked the growth of MYC-hyperactivated cells. Pharmacological inhibition of IRE1 RNase activity with small molecule inhibitor 8866 selectively restrained the MYC-overexpressing tumor growth in vivo in a cohort of preclinical patient-derived xenograft models and genetically engineered mouse models. Strikingly, 8866 substantially enhanced the efficacy of docetaxel chemotherapy, resulting in rapid regression of MYC-overexpressing tumors. Collectively, these data establish the synthetic lethal interaction of the IRE1/XBP1 pathway with MYC hyperactivation and provide a potential therapy for MYC-driven human breast cancers.

[Expression of c-jun protein after experimental rat brain concussion].

PubMed

Wang, Feng; Li, Yong-hong

2010-02-01

To observe e-jun protein expression after rat brain concussion and explore the forensic pathologic markers following brain concussion. Fifty-five rats were randomly divided into brain concussion group and control group. The expression of c-jun protein was observed by immunohistochemistry. There were weak positive expression of c-jun protein in control group. In brain concussion group, however, some neutrons showed positive expression of c-jun protein at 15 min after brain concussion, and reach to the peak at 3 h after brain concussion. The research results suggest that detection of c-jun protein could be a marker to determine brain concussion and estimate injury time after brain concussion.

Human amniotic epithelial cell feeder layers maintain mouse embryonic stem cell pluripotency via epigenetic regulation of the c-Myc promoter.

PubMed

Liu, Te; Cheng, Weiwei; Liu, Tianjin; Guo, Lihe; Huang, Qin; Jiang, Lizhen; Du, Xiling; Xu, Fuhui; Liu, Zhixue; Lai, Dongmei

2010-02-01

Mouse embryonic stem cells (ESCs) are typically cultured on a feeder layer of mouse embryonic fibroblasts (MEFs), with leukemia inhibitory factor (LIF) added to maintain them in an undifferentiated state. We have previously shown that human amniotic epithelial cells (hAECs) can be used as feeder cells to maintain mouse ESC pluripotency, but the mechanism for this is unknown. In the present study, we found that CpG islands 5' of the c-Myc gene remain hypomethylated in mouse ESCs cultured on hAECs. In addition, levels of acetylation of histone H3 and trimethylation of histone H3K4 in the c-Myc gene promoter were higher in ES cells cultured on hAECs than those in ES cells cultured on MEFs. These data suggested that hAECs can alter mouse ESC gene expression via epigenetic modification of c-Myc, providing a possible mechanism for the hAEC-induced maintenance of ESCs in an undifferentiated state.

Surface-Enhanced Raman Scattering Surface Selection Rules for the Proteomic Liquid Biopsy in Real Samples: Efficient Detection of the Oncoprotein c-MYC.

PubMed

Pazos, Elena; Garcia-Algar, Manuel; Penas, Cristina; Nazarenus, Moritz; Torruella, Arnau; Pazos-Perez, Nicolas; Guerrini, Luca; Vázquez, M Eugenio; Garcia-Rico, Eduardo; Mascareñas, José L; Alvarez-Puebla, Ramon A

2016-11-02

Blood-based biomarkers (liquid biopsy) offer extremely valuable tools for the noninvasive diagnosis and monitoring of tumors. The protein c-MYC, a transcription factor that has been shown to be deregulated in up to 70% of human cancers, can be used as a robust proteomic signature for cancer. Herein, we developed a rapid, highly specific, and sensitive surface-enhanced Raman scattering (SERS) assay for the quantification of c-MYC in real blood samples. The sensing scheme relies on the use of specifically designed hybrid plasmonic materials and their bioderivatization with a selective peptidic receptor modified with a SERS transducer. Peptide/c-MYC recognition events translate into measurable alterations of the SERS spectra associated with a molecular reorientation of the transducer, in agreement with the surface selection rules. The efficiency of the sensor is demonstrated in cellular lines, healthy donors and a cancer patient.

Overproduction of v-Myc in the nucleus and its excess over Max are not required for avian fibroblast transformation.

PubMed Central

Tikhonenko, A T; Hartman, A R; Linial, M L

1993-01-01

The cellular proto-oncogene c-myc can acquire transforming potential by a number of different means, including retroviral transduction. The transduced allele generally contains point mutations relative to c-myc and is overexpressed in infected cells, usually as a v-Gag-Myc fusion protein. Upon synthesis, v-Gag-Myc enters the nucleus, forms complexes with its heterodimeric partner Max, and in this complex binds to DNA in a sequence-specific manner. To delineate the role for each of these events in fibroblast transformation, we introduced several mutations into the myc gene of the avian retrovirus MC29. We observed that Gag-Myc with a mutated nuclear localization signal is confined predominantly in the cytoplasm and only about 5% of the protein could be detected in the nucleus (less than the amount of endogenous c-Myc). Consequently, only a small fraction of Max is associated with Myc. However, cells infected with this mutant exhibit a completely transformed phenotype in vitro, suggesting that production of enough v-Gag-Myc to tie up all cellular Max is not needed for transformation. While the nuclear localization signal is dispensable for transformation, minimal changes in the v-Gag-Myc DNA-binding domain completely abolish its transforming potential, consistent with a role of Myc as a transcriptional regulator. One of its potential targets might be the endogenous c-myc, which is repressed in wild-type MC29-infected cells. Our experiments with MC29 mutants demonstrate that c-myc down-regulation depends on the integrity of the v-Myc DNA-binding domain and occurs at the RNA level. Hence, it is conceivable that v-Gag-Myc, either directly or circuitously, regulates c-myc transcription. Images PMID:8497274

Loss of connective tissue growth factor as an unfavorable prognosis factor activates miR-18b by PI3K/AKT/C-Jun and C-Myc and promotes cell growth in nasopharyngeal carcinoma.

PubMed

Yu, X; Zhen, Y; Yang, H; Wang, H; Zhou, Y; Wang, E; Marincola, F M; Mai, C; Chen, Y; Wei, H; Song, Y; Lyu, X; Ye, Y; Cai, L; Wu, Q; Zhao, M; Hua, S; Fu, Q; Zhang, Y; Yao, K; Liu, Z; Li, X; Fang, W

2013-05-16

Connective tissue growth factor (CTGF) has different roles in different types of cancer. However, the involvement and molecular basis of CTGF in tumor progression and prognosis of human nasopharyngeal carcinoma (NPC) have almost never been reported. In this study, we observed that downregulated CTGF expression was significantly associated with NPC progression and poor prognosis. Knockdown of CTGF markedly elevated the ability of cell proliferation in vivo and in vitro. Subsequently, we discovered that the reduction of CTGF increased the expression of miR-18b, an oncomir-promoting cell proliferation. Further, we discovered that attenuated CTGF-mediated upregulation of miR-18b was dependent on the increased binding of transcription factors Jun proto-oncogene (C-Jun) and v-Myc myelocytomatosis viral oncogene homolog (C-Myc) to miR-18b promoter region via phosphoinositide 3-kinase (PI3K)/AKT pathway. Finally, we further found that miR-18b directly suppressed the expression of CTGF in NPC. In clinical fresh specimens, miR-18b was widely overexpressed and inversely correlated with CTGF expression in NPC. Our studies are the first to demonstrate that reduced CTGF as an unfavorable prognosis factor mediates the activation of miR-18b, an oncomir directly suppresses CTGF expression, by PI3K/AKT/C-Jun and C-Myc and promotes cell growth of NPC.

Vitamin K2 and cotylenin A synergistically induce monocytic differentiation and growth arrest along with the suppression of c-MYC expression and induction of cyclin G2 expression in human leukemia HL-60 cells.

PubMed

Maniwa, Yasuhisa; Kasukabe, Takashi; Kumakura, Shunichi

2015-08-01

Although all-trans retinoic acid (ATRA) is a standard and effective drug used for differentiation therapy in acute promyelocytic leukemia, ATRA-resistant leukemia cells ultimately emerge during this treatment. Therefore, the development of new drugs or effective combination therapy is urgently needed. We demonstrate that the combined treatment of vitamin K2 and cotylenin A synergistically induced monocytic differentiation in HL-60 cells. This combined treatment also synergistically induced NBT-reducing activity and non-specific esterase-positive cells as well as morphological changes to monocyte/macrophage-like cells. Vitamin K2 and cotylenin A cooperatively inhibited the proliferation of HL-60 cells in short-term and long-term cultures. This treatment also induced growth arrest at the G1 phase. Although 5 µg/ml cotylenin A or 5 µM vitamin K2 alone reduced c-MYC gene expression in HL-60 cells to approximately 45% or 80% that of control cells, respectively, the combined treatment almost completely suppressed c-MYC gene expression. We also demonstrated that the combined treatment of vitamin K2 and cotylenin A synergistically induced the expression of cyclin G2, which had a positive effect on the promotion and maintenance of cell cycle arrest. These results suggest that the combination of vitamin K2 and cotylenin A has therapeutic value in the treatment of acute myeloid leukemia.

Detecting and Targeting Oncogenic Myc in Breast Cancer

DTIC Science & Technology

2006-06-01

expression in lung tumor samples. Real-time quantitative PCR amplification was conducted using the SYBR Green assay in the ABI PRISM 7900-HT (Applied...Methylation-sensitive se- quence-specific DNA binding by the c-Myc basic region. Science 1991;251:186–9. 37. Perini G, Diolaiti D, Porro A, et al. In...using nuclear magnetic resonance and circular dichroism. We show that several Myc NTD polypeptides are largely disordered in solution, which is

Hyper-O-GlcNAcylation induces cisplatin resistance via regulation of p53 and c-Myc in human lung carcinoma.

PubMed

Luanpitpong, Sudjit; Angsutararux, Paweorn; Samart, Parinya; Chanthra, Nawin; Chanvorachote, Pithi; Issaragrisil, Surapol

2017-09-06

Aberrant metabolism in hexosamine biosynthetic pathway (HBP) has been observed in several cancers, affecting cellular signaling and tumor progression. However, the role of O-GlcNAcylation, a post-translational modification through HBP flux, in apoptosis remains unclear. Here, we found that hyper-O-GlcNAcylation in lung carcinoma cells by O-GlcNAcase inhibition renders the cells to apoptosis resistance to cisplatin (CDDP). Profiling of various key regulatory proteins revealed an implication of either p53 or c-Myc in the apoptosis regulation by O-GlcNAcylation, independent of p53 status. Using co-immunoprecipitation and correlation analyses, we found that O-GlcNAcylation of p53 under certain cellular contexts, i.e. high p53 activation, promotes its ubiquitin-mediated proteasomal degradation, resulting in a gain of oncogenic and anti-apoptotic functions. By contrast, O-GlcNAcylation of c-Myc inhibits its ubiquitination and subsequent proteasomal degradation. Gene manipulation studies revealed that O-GlcNAcylation of p53/c-Myc is in part a regulator of CDDP-induced apoptosis. Accordingly, we classified CDDP resistance by hyper-O-GlcNAcylation in lung carcinoma cells as either p53 or c-Myc dependence based on their molecular targets. Together, our findings provide novel mechanisms for the regulation of lung cancer cell apoptosis that could be important in understanding clinical drug resistance and suggest O-GlcNAcylation as a potential target for cancer therapy.

Major cancer protein amplifies global gene expression

Cancer.gov

Scientists may have discovered why a protein called MYC can provoke a variety of cancers. Like many proteins associated with cancer, MYC helps regulate cell growth. A new study carried out by researchers at the National Institutes of Health and colleagues

Myeloma-derived macrophage inhibitory factor regulates bone marrow stromal cell-derived IL-6 via c-MYC.

PubMed

Piddock, Rachel E; Marlein, Christopher R; Abdul-Aziz, Amina; Shafat, Manar S; Auger, Martin J; Bowles, Kristian M; Rushworth, Stuart A

2018-05-16

Multiple myeloma (MM) remains an incurable malignancy despite the recent advancements in its treatment. The protective effects of the niche in which it develops has been well documented; however, little has been done to investigate the MM cell's ability to 're-program' cells within its environment to benefit disease progression. Here, we show that MM-derived macrophage migratory inhibitory factor (MIF) stimulates bone marrow stromal cells to produce the disease critical cytokines IL-6 and IL-8, prior to any cell-cell contact. Furthermore, we provide evidence that this IL-6/8 production is mediated by the transcription factor cMYC. Pharmacological inhibition of cMYC in vivo using JQ1 led to significantly decreased levels of serum IL-6-a highly positive prognostic marker in MM patients. Our presented findings show that MM-derived MIF causes BMSC secretion of IL-6 and IL-8 via BMSC cMYC. Furthermore, we show that the cMYC inhibitor JQ1 can reduce BMSC secreted IL-6 in vivo, irrespective of tumor burden. These data provide evidence for the clinical evaluation of both MIF and cMYC inhibitors in the treatment of MM.

The Phosphoinositide 3-Kinase p110α Isoform Regulates Leukemia Inhibitory Factor Receptor Expression via c-Myc and miR-125b to Promote Cell Proliferation in Medulloblastoma

PubMed Central

von Bueren, André O.; Ćwiek, Paulina; Rehrauer, Hubert; Djonov, Valentin; Anderle, Pascale; Arcaro, Alexandre

2015-01-01

Medulloblastoma (MB) is the most common malignant brain tumor in childhood and represents the main cause of cancer-related death in this age group. The phosphoinositide 3-kinase (PI3K) pathway has been shown to play an important role in the regulation of medulloblastoma cell survival and proliferation, but the molecular mechanisms and downstream effectors underlying PI3K signaling still remain elusive. The impact of RNA interference (RNAi)-mediated silencing of PI3K isoforms p110α and p110δ on global gene expression was investigated by DNA microarray analysis in medulloblastoma cell lines. A subset of genes with selectively altered expression upon p110α silencing in comparison to silencing of the closely related p110δ isoform was revealed. Among these genes, the leukemia inhibitory factor receptor α (LIFR α) was validated as a novel p110α target in medulloblastoma. A network involving c-Myc and miR-125b was shown to be involved in the control of LIFRα expression downstream of p110α. Targeting the LIFRα by RNAi, or by using neutralizing reagents impaired medulloblastoma cell proliferation in vitro and induced a tumor volume reduction in vivo. An analysis of primary tumors revealed that LIFRα and p110α expression were elevated in the sonic hedgehog (SHH) subgroup of medulloblastoma, indicating its clinical relevance. Together, these data reveal a novel molecular signaling network, in which PI3K isoform p110α controls the expression of LIFRα via c-Myc and miR-125b to promote MB cell proliferation. PMID:25915540

Encapsulation of c-myc antisense oligodeoxynucleotides in lipid particles improves antitumoral efficacy in vivo in a human melanoma line.

PubMed

Leonetti, C; Biroccio, A; Benassi, B; Stringaro, A; Stoppacciaro, A; Semple, S C; Zupi, G

2001-06-01

Phosphorothioate c-myc antisense oligodeoxynucleotides [S]ODNs (free INX-6295) were encapsulated in a new liposome formulation and the antitumor activity was compared to the unencapsulated antisense in a human melanoma xenograft. The systemic administration of INX-6295 encapsulated in stabilized antisense lipid particles (SALP INX-6295) improved plasma AUC (area under the plasma concentration-time curve) and initial half-life of free INX-6295, resulting in a significant enhancement in tumor accumulation and improvement in tumor distribution of antisense oligodeoxynucleotides. Animals treated with SALP INX-6295 exhibited a prolonged reduction of c-myc expression, reduced tumor growth and increased mice survival. When administered in combination with cisplatin (DDP), SALP INX-6295 produced a complete tumor regression in approximately 30% of treated mice, which persisted for at least 60 days following the first cycle of treatment. Finally, the median survival of mice treated with DDP/SALP INX-6295 increased by 105% compared to 84% for animals treated with the combination DDP/free INX-6295. These data indicate that the biological activity and the therapeutic efficacy of c-myc antisense therapy may be improved when these agents are administered in lipid-based delivery systems.

Id2 leaves the chromatin of the E2F4–p130-controlled c-myc promoter during hepatocyte priming for liver regeneration

PubMed Central

Rodríguez, José L.; Sandoval, Juan; Serviddio, Gaetano; Sastre, Juan; Morante, María; Perrelli, Maria-Giulia; Martínez-Chantar, María L.; Viña, José; Viña, Juan R.; Mato, José M.; Ávila, Matías A.; Franco, Luis; López-Rodas, Gerardo; Torres, Luis

2006-01-01

The Id (inhibitor of DNA binding or inhibitor of differentiation) helix–loop–helix proteins are involved in the regulation of cell growth, differentiation and cancer. The fact that the molecular mechanisms of liver regeneration are not completely understood prompted us to study the fate of Id2 in proliferating liver. Id2 increases in liver regeneration after partial hepatectomy, following the early induction of its gene. Co-immunoprecipitation shows that Id2 forms a complex with E2F4, p130 and mSin3A in quiescent liver and all these components are present at the c-myc promoter as shown using ChIP (chromatin immunoprecipitation). Activation of c-myc during hepatocyte priming (G0–G1 transition) correlates with the dissociation of Id2 and HDAC (histone deacetylase), albeit p130 remains bound at least until 6 h. Moreover, as the G0–G1 transition progresses, Id2 and HDAC again bind the c-myc promoter concomitantly with the repression of this gene. The time course of c-myc binding to the Id2 promoter, as determined by ChIP assays is compatible with a role of the oncoprotein as a transcriptional inducer of Id2 in liver regeneration. Immunohistochemical analysis shows that Id2 also increases in proliferating hepatocytes after bile duct ligation. In this case, the pattern of Id2 presence in the c-myc promoter parallels that found in regenerating liver. Our results may suggest a control role for Id2 in hepatocyte priming, through a p130 dissociation-independent regulation of c-myc. PMID:16776654

The TLR3/TICAM-1 signal constitutively controls spontaneous polyposis through suppression of c-Myc in Apc Min/+ mice.

PubMed

Ono, Junya; Shime, Hiroaki; Takaki, Hiromi; Takashima, Ken; Funami, Kenji; Yoshida, Sumito; Takeda, Yohei; Matsumoto, Misako; Kasahara, Masanori; Seya, Tsukasa

2017-10-17

Intestinal tumorigenesis is promoted by myeloid differentiation primary response gene 88 (MyD88) activation in response to the components of microbiota in Apc Min/+ mice. Microbiota also contains double-stranded RNA (dsRNA), a ligand for TLR3, which activates the toll-like receptor adaptor molecule 1 (TICAM-1, also known as TRIF) pathway. We established Apc Min/+ Ticam1 -/- mice and their survival was compared to survival of Apc Min/+ Myd88 -/- and wild-type (WT) mice. The properties of polyps were investigated using immunofluorescence staining and RT-PCR analysis. We demonstrate that TICAM-1 is essential for suppression of polyp formation in Apc Min/+ mice. TICAM-1 knockout resulted in shorter survival of mice compared to WT mice or mice with knockout of MyD88 in the Apc Min/+ background. Polyps were more frequently formed in the distal intestine of Apc Min/+ Ticam1 -/- mice than in Apc Min/+ mice. Infiltration of immune cells such as CD11b + and CD8α + cells into the polyps was detected histologically. CD11b and CD8α mRNAs were increased in polyps of Apc Min/+ Ticam1 -/- mice compared to Apc Min/+ mice. Gene expression of inducible nitric oxide synthase (iNOS), interferon (IFN)-γ, CXCL9 and IL-12p40 was increased in polyps of Apc Min/+ Ticam1 -/- mice. mRNA and protein expression of c-Myc, a critical transcription factor for inflammation-associated polyposis, were increased in polyps of Apc Min/+ Ticam1 -/- mice. A Lactobacillus strain producing dsRNA was detected in feces of Apc Min/+ mice. These results imply that the TLR3/TICAM-1 pathway inhibits polyposis through suppression of c-Myc expression and supports long survival in Apc Min/+ mice.

MYC and gastric adenocarcinoma carcinogenesis

PubMed Central

Calcagno, Danielle Queiroz; Leal, Mariana Ferreira; Assumpção, Paulo Pimentel; Smith, Marília de Arruda Cardoso; Burbano, Rommel Rodríguez

2008-01-01

MYC is an oncogene involved in cell cycle regulation, cell growth arrest, cell adhesion, metabolism, ribosome biogenesis, protein synthesis, and mitochondrial function. It has been described as a key element of several carcinogenesis processes in humans. Many studies have shown an association between MYC deregulation and gastric cancer. MYC deregulation is also seen in gastric preneoplastic lesions and thus it may have a role in early gastric carcinogenesis. Several studies have suggested that amplification is the main mechanism of MYC deregulation in gastric cancer. In the present review, we focus on the deregulation of the MYC oncogene in gastric adenocarcinoma carcinogenesis, including its association with Helicobacter pylori (H pylori) and clinical applications. PMID:18932273

[Construction of cTnC-linker-TnI (P) Genes, Expression of Fusion Protein and Preparation of Lyophilized Protein].

PubMed

Song, Xiaoli; Liu, Xiaoyun; Cai, Lei; Wu, Jianwei; Wang, Jihua

2015-12-01

In order to construct and express human cardiac troponin C-linker-troponin I(P) [ cTnC-linker-TnI(P)] fusion protein, detect its activity and prepare lyophilized protein, we searched the CDs of human cTnC and cTnI from GenBank, synthesized cTnC and cTnI(30-110aa) into cloning vector by a short DNA sequence coding for 15 neutral amino acid residues. pCold I-cTnC-linker-TnI(P) was constructed and transformed into E. coli BL21(DE3). Then, cTnC-linker-TnI(P) fusion protein was induced by isopropyl-β-D-thiogalactopyranoside (IPTG). Soluable expression of cTnC-linker-TnI(P) in prokaryotic system was successfully obtained. The fusion protein was purified by Ni²⁺ Sepharose 6 Fast Flow affinity chromatography with over 95% purity and prepared into lyophilized protein. The activity of purified cTnC-linker-TnI(P) and its lyophilized protein were detected by Wondfo Finecare™ cTnI Test. Lyophilized protein of cTnC-linker-TnI(P) was stable for 10 or more days at 37 °C and 4 or more months at 25 °C and 4 °C. The expression system established in this research is feasible and efficient. Lyophilized protein is stable enough to be provided as biological raw materials for further research.

Myc-Driven Glycolysis Is a Therapeutic Target in Glioblastoma.

PubMed

Tateishi, Kensuke; Iafrate, A John; Ho, Quan; Curry, William T; Batchelor, Tracy T; Flaherty, Keith T; Onozato, Maristela L; Lelic, Nina; Sundaram, Sudhandra; Cahill, Daniel P; Chi, Andrew S; Wakimoto, Hiroaki

2016-09-01

Deregulated Myc drives an oncogenic metabolic state, including pseudohypoxic glycolysis, adapted for the constitutive production of biomolecular precursors to feed rapid tumor cell growth. In glioblastoma, Myc facilitates renewal of the tumor-initiating cell reservoir contributing to tumor maintenance. We investigated whether targeting the Myc-driven metabolic state could be a selectively toxic therapeutic strategy for glioblastoma. The glycolytic dependency of Myc-driven glioblastoma was tested using (13)C metabolic flux analysis, glucose-limiting culture assays, and glycolysis inhibitors, including inhibitors of the NAD(+) salvage enzyme nicotinamide phosphoribosyl-transferase (NAMPT), in MYC and MYCN shRNA knockdown and lentivirus overexpression systems and in patient-derived glioblastoma tumorspheres with and without MYC/MYCN amplification. The in vivo efficacy of glycolyic inhibition was tested using NAMPT inhibitors in MYCN-amplified patient-derived glioblastoma orthotopic xenograft mouse models. Enforced Myc overexpression increased glucose flux and expression of glycolytic enzymes in glioblastoma cells. Myc and N-Myc knockdown and Myc overexpression systems demonstrated that Myc activity determined sensitivity and resistance to inhibition of glycolysis. Small-molecule inhibitors of glycolysis, particularly NAMPT inhibitors, were selectively toxic to MYC/MYCN-amplified patient-derived glioblastoma tumorspheres. NAMPT inhibitors were potently cytotoxic, inducing apoptosis and significantly extended the survival of mice bearing MYCN-amplified patient-derived glioblastoma orthotopic xenografts. Myc activation in glioblastoma generates a dependency on glycolysis and an addiction to metabolites required for glycolysis. Glycolytic inhibition via NAMPT inhibition represents a novel metabolically targeted therapeutic strategy for MYC or MYCN-amplified glioblastoma and potentially other cancers genetically driven by Myc. Clin Cancer Res; 22(17); 4452-65. ©2016 AACR

Myc-induced anchorage of the rDNA IGS region to nucleolar matrix modulates growth-stimulated changes in higher-order rDNA architecture

PubMed Central

Shiue, Chiou-Nan; Nematollahi-Mahani, Amir; Wright, Anthony P.H.

2014-01-01

Chromatin domain organization and the compartmentalized distribution of chromosomal regions are essential for packaging of deoxyribonucleic acid (DNA) in the eukaryotic nucleus as well as regulated gene expression. Nucleoli are the most prominent morphological structures of cell nuclei and nucleolar organization is coupled to cell growth. It has been shown that nuclear scaffold/matrix attachment regions often define the base of looped chromosomal domains in vivo and that they are thereby critical for correct chromosome architecture and gene expression. Here, we show regulated organization of mammalian ribosomal ribonucleic acid genes into distinct chromatin loops by tethering to nucleolar matrix via the non-transcribed inter-genic spacer region of the ribosomal DNA (rDNA). The rDNA gene loop structures are induced specifically upon growth stimulation and are dependent on the activity of the c-Myc protein. Matrix-attached rDNA genes are hypomethylated at the promoter and are thus available for transcriptional activation. rDNA genes silenced by methylation are not recruited to the matrix. c-Myc, which has been shown to induce rDNA transcription directly, is physically associated with rDNA gene looping structures and the intergenic spacer sequence in growing cells. Such a role of Myc proteins in gene activation has not been reported previously. PMID:24609384

Cooperative interplay of let-7 mimic and HuR with MYC RNA

PubMed Central

Gunzburg, Menachem J; Sivakumaran, Andrew; Pendini, Nicole R; Yoon, Je-Hyun; Gorospe, Myriam; Wilce, Matthew Cj; Wilce, Jacqueline A

2015-01-01

Both RNA-binding proteins (RBP) and miRNA play important roles in the regulation of mRNA expression, often acting together to regulate a target mRNA. In some cases the RBP and miRNA have been reported to act competitively, but in other instances they function cooperatively. Here, we investigated HuR function as an enhancer of let-7-mediated translational repression of c-Myc despite the separation of their binding sites. Using an in vitro system, we determined that a let-7 mimic, consisting of single-stranded (ss)DNA complementary to the let-7 binding site, enhanced the affinity of HuR for a 122-nt MYC RNA encompassing both binding sites. This finding supports the biophysical principle of cooperative binding by an RBP and miRNA purely through interactions at distal mRNA binding sites. PMID:26177105

Cooperative interplay of let-7 mimic and HuR with MYC RNA.

PubMed

Gunzburg, Menachem J; Sivakumaran, Andrew; Pendini, Nicole R; Yoon, Je-Hyun; Gorospe, Myriam; Wilce, Matthew C J; Wilce, Jacqueline A

2015-01-01

Both RNA-binding proteins (RBP) and miRNA play important roles in the regulation of mRNA expression, often acting together to regulate a target mRNA. In some cases the RBP and miRNA have been reported to act competitively, but in other instances they function cooperatively. Here, we investigated HuR function as an enhancer of let-7-mediated translational repression of c-Myc despite the separation of their binding sites. Using an in vitro system, we determined that a let-7 mimic, consisting of single-stranded (ss)DNA complementary to the let-7 binding site, enhanced the affinity of HuR for a 122-nt MYC RNA encompassing both binding sites. This finding supports the biophysical principle of cooperative binding by an RBP and miRNA purely through interactions at distal mRNA binding sites.

Analysis of differential protein expression by cisplatin treatment in cervical carcinoma cells.

PubMed

Yim, E-K; Lee, K-H; Kim, C-J; Park, J-S

2006-01-01

Cisplatin (cis-diaminedichloroplatinum), a DNA-damaging agent, which readily induces apoptosis in vitro, is one of the widely used anticancer drug in the treatment of human malignancies. Cisplatin has played an important role in cervical cancer management for effective chemotherapeutic regimen, but the underlying mechanisms inducing cell death at protein level are unknown. Using proteome analysis, an investigation aimed at a better understanding of the antiproliferative mechanisms by cisplatin was carried out in HeLa cervical carcinoma cells. In total, 21 protein spots were found to be differentially expressed following cisplatin treatment, of which 12 were upregulated (eg, regulator of G-protein signaling, TRAF:TNF (tumor necrosis factor) receptor-associated factor-interacting protein [I-TRAF], and cyclin-dependent kinase inhibitor p27 [p27(kip1)]) and 9 were downregulated (eg, myc proto-oncoprotein [c-myc] and proliferating cell nuclear antigen). Interestingly, we found the upregulation of proliferating cell nuclear antigen, which used molecular marker in cervical cancer screening. On the basis of proteomic data, we showed that cisplatin induced TRAF2-mediated NF-kappaB downregulation. In addition, our study demonstrated that cisplatin induced membrane death receptor-mediated and mitochondria-mediated apoptosis pathway. Our findings may offer new insights into the antiproliferative mechanism by cisplatin and its mode of action in cervical carcinoma cells.

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...

Physical and Functional Interactions of Human Endogenous Retrovirus Proteins Np9 and Rec with the Promyelocytic Leukemia Zinc Finger Protein▿

PubMed Central

Denne, Miriam; Sauter, Marlies; Armbruester, Vivienne; Licht, Jonathan D.; Roemer, Klaus; Mueller-Lantzsch, Nikolaus

2007-01-01

Only few of the human endogenous retrovirus (HERV) sequences in the human genome can produce proteins. We have previously reported that (i) patients with germ cell tumors often make antibodies against proteins encoded by HERV-K elements, (ii) expression of the HERV-K rec gene in transgenic mice can interfere with germ cell development and induce carcinoma in situ, and (iii) HERV-K np9 transcript is overproduced in many tumors including breast cancers. Here we document that both Np9 and Rec physically and functionally interact with the promyelocytic leukemia zinc finger (PLZF) tumor suppressor, a transcriptional repressor and chromatin remodeler implicated in cancer and the self-renewal of spermatogonial stem cells. Interaction is mediated via two different central and C-terminal domains of Np9 and Rec and the C-terminal zinc fingers of PLZF. One major target of PLZF is the c-myc proto-oncogene. Coexpression of Np9 and Rec with PLZF abrogates the transcriptional repression of the c-myc gene promoter by PLZF and results in c-Myc overproduction, altered expression of c-Myc-regulated genes, and corresponding effects on cell proliferation and survival. Thus, the human endogenous retrovirus proteins Np9 and Rec may act oncogenically by derepressing c-myc through the inhibition of PLZF. PMID:17360752

Point Mutations in c-Myc Uncouple Neoplastic Transformation from Multiple Other Phenotypes in Rat Fibroblasts

PubMed Central

Graves, J. Anthony; Rothermund, Kristi; Wang, Tao; Qian, Wei; Van Houten, Bennett; Prochownik, Edward V.

2010-01-01

Deregulation of c-Myc (Myc) occurs in many cancers. In addition to transforming various cell types, Myc also influences additional transformation-associated cellular phenotypes including proliferation, survival, genomic instability, reactive oxygen species production, and metabolism. Although Myc is wild type in most cancers (wtMyc), it occasionally acquires point mutations in certain lymphomas. Some of these mutations confer a survival advantage despite partially attenuating proliferation and transformation. Here, we have evaluated four naturally-occurring or synthetic point mutations of Myc for their ability to affect these phenotypes, as well as to promote genomic instability, to generate reactive oxygen species and to up-regulate aerobic glycolysis and oxidative phosphorylation. Our findings indicate that many of these phenotypes are genetically and functionally independent of one another and are not necessary for transformation. Specifically, the higher rate of glucose metabolism known to be associated with wtMyc deregulation was found to be independent of transformation. One mutation (Q131R) was greatly impaired for nearly all of the studied Myc phenotypes, yet was able to retain some ability to transform. These findings indicate that, while the Myc phenotypes examined here make additive contributions to transformation, none, with the possible exception of increased reliance on extracellular glutamine for survival, are necessary for achieving this state. PMID:21060841

Circular RNA hsa_circRNA_103809 promotes lung cancer progression via facilitating ZNF121-dependent MYC expression by sequestering miR-4302.

PubMed

Liu, Wei; Ma, Weiming; Yuan, Yuan; Zhang, Youwei; Sun, Sanyuan

2018-06-12

Lung cancer characterized with malignant cell growth is the leading cause of cancer-related deaths. In recent years, several circular RNAs (circRNAs) have been reported to participate in lung cancer progression. However, the correlation between circular RNA (circRNA) and lung cancer still remains to be further investigated. In this study, we screened out a highly expressed circular RNA hsa_circRNA_103809 in lung cancer tissues. We showed hsa_circRNA_103809 could serve as a prognostic biomarker for patients with lung cancer. Furthermore, we found that hsa_circRNA_103809 knockdown significantly suppressed lung cancer cell proliferation and invasion in vitro and delayed tumor growth in vivo. In mechanism, we identified hsa_circRNA_103809 as a sponge of miR-4302 targeting ZNF121. By sequestering miR-4302, hsa_circRNA_103809 promoted the expression of ZNF121 which consequently enhanced MYC protein level in lung cancer cells. Through rescue assays, we demonstrated hsa_circRNA_103809 contributed to lung cancer cell proliferation and invasion via facilitating ZNF121-dependent MYC expression by sponging miR-4302. In conclusion, our findings illustrated a novel hsa_circRNA_103809/miR-4302/ZNF121/MYC regulatory signaling pathway in lung cancer progression. Copyright © 2018 Elsevier Inc. All rights reserved.

Destabilization of MYC/MYCN by the mitochondrial inhibitors, metaiodobenzylguanidine, metformin and phenformin

PubMed Central

WANG, STEPHANIE S.; HSIAO, RUTH; LIMPAR, MARIKO M.; LOMAHAN, SARAH; TRAN, TUAN-ANH; MALONEY, NOLAN J.; IKEGAKI, NAOHIKO; TANG, XAO X.

2014-01-01

In the present study, we investigated the anticancer effects of the mitochondrial inhibitors, metaiodobenzylguanidine (MIBG), metformin and phenformin. 131I-MIBG has been used for scintigraphic detection and the targeted radiotherapy of neuroblastoma (NB), a pediatric malignancy. Non-radiolabeled MIBG has been reported to be cytotoxic to NB cells in vitro and in vivo. However, the mechanisms behind its growth suppressive effects have not yet been fully elucidated. Metformin and phenformin are diabetes medications that are being considered in anticancer therapeutics. We investigated the anticancer mechanisms of action of MIBG and metformin in NB. Our data revealed that both drugs suppressed NB cell growth and that the combination drug treatment was more potent. MIBG reduced MYCN and MYC expression in MYCN-amplified and non-MYCN-amplified NB cells in a dose- and time-dependent manner. Metformin was less effective than MIBG in destabilizing MYC/MYCN. The treatment of NB cells with metformin or MIBG resulted in an increased expression of genes encoding biomarkers for favorable outcome in NB [(ephrin (EFN)B2, EFNB3, EPH receptor B6 (EPHB6), neurotrophic tyrosine kinase, receptor, type 1 (NTRK1), CD44 and Myc-interacting zinc finger protein (MIZ-1)] and tumor suppressor genes [(early growth response 1 (EGR1), EPH receptor A2 (EPHA2), growth arrest and DNA-damage-inducible, beta (GADD45B), neuregulin 1 (NRG1), TP53 apoptosis effector (PERP) and sel-1 suppressor of lin-12-like (C. elegans) (SEL1L)]. Accordingly, metformin and MIBG augmented histone H3 acetylation in these cells. Phenformin also exhibited histone modification and was more effective than metformin in destabilizing MYC/MYCN in NB cells. Our data suggest that the destabilization of MYC/MYCN by MIBG, metformin and phenformin and their effects on histone modification are important mechanisms underlying their anticancer effects. PMID:24190252

Destabilization of MYC/MYCN by the mitochondrial inhibitors, metaiodobenzylguanidine, metformin and phenformin.

PubMed

Wang, Stephanie S; Hsiao, Ruth; Limpar, Mariko M; Lomahan, Sarah; Tran, Tuan-Anh; Maloney, Nolan J; Ikegaki, Naohiko; Tang, Xao X

2014-01-01

In the present study, we investigated the anticancer effects of the mitochondrial inhibitors, metaiodobenzylguanidine (MIBG), metformin and phenformin. 131I-MIBG has been used for scintigraphic detection and the targeted radiotherapy of neuroblastoma (NB), a pediatric malignancy. Non-radiolabeled MIBG has been reported to be cytotoxic to NB cells in vitro and in vivo. However, the mechanisms behind its growth suppressive effects have not yet been fully elucidated. Metformin and phenformin are diabetes medications that are being considered in anticancer therapeutics. We investigated the anticancer mechanisms of action of MIBG and metformin in NB. Our data revealed that both drugs suppressed NB cell growth and that the combination drug treatment was more potent. MIBG reduced MYCN and MYC expression in MYCN-amplified and non-MYCN-amplified NB cells in a dose- and time-dependent manner. Metformin was less effective than MIBG in destabilizing MYC/MYCN. The treatment of NB cells with metformin or MIBG resulted in an increased expression of genes encoding biomarkers for favorable outcome in NB [(ephrin (EFN)B2, EFNB3, EPH receptor B6 (EPHB6), neurotrophic tyrosine kinase, receptor, type 1 (NTRK1), CD44 and Myc-interacting zinc finger protein (MIZ-1)] and tumor suppressor genes [(early growth response 1 (EGR1), EPH receptor A2 (EPHA2), growth arrest and DNA-damage-inducible, beta (GADD45B), neuregulin 1 (NRG1), TP53 apoptosis effector (PERP) and sel-1 suppressor of lin-12-like (C. elegans) (SEL1L)]. Accordingly, metformin and MIBG augmented histone H3 acetylation in these cells. Phenformin also exhibited histone modification and was more effective than metformin in destabilizing MYC/MYCN in NB cells. Our data suggest that the destabilization of MYC/MYCN by MIBG, metformin and phenformin and their effects on histone modification are important mechanisms underlying their anticancer effects.

Targeting MUC1-C suppresses polycomb repressive complex 1 in multiple myeloma.

PubMed

Tagde, Ashujit; Markert, Tahireh; Rajabi, Hasan; Hiraki, Masayuki; Alam, Maroof; Bouillez, Audrey; Avigan, David; Anderson, Kenneth; Kufe, Donald

2017-09-19

The polycomb repressive complex 1 (PRC1) includes the BMI1, RING1 and RING2 proteins. BMI1 is required for survival of multiple myeloma (MM) cells. The MUC1-C oncoprotein is aberrantly expressed by MM cells, activates MYC and is also necessary for MM cell survival. The present studies show that targeting MUC1-C with (i) stable and inducible silencing and CRISPR/Cas9 editing and (ii) the pharmacologic inhibitor GO-203, which blocks MUC1-C function, downregulates BMI1, RING1 and RING2 expression. The results demonstrate that MUC1-C drives BMI1 transcription by a MYC-dependent mechanism. MUC1-C thus promotes MYC occupancy on the BMI1 promoter and thereby activates BMI1 expression. We also show that the MUC1-C→MYC pathway induces RING2 expression. Moreover, in contrast to BMI1 and RING2, we found that MUC1-C drives RING1 by an NF-κB p65-dependent mechanism. Targeting MUC1-C and thereby the suppression of these key PRC1 proteins was associated with downregulation of the PRC1 E3 ligase activity as evidenced by decreases in ubiquitylation of histone H2A. Targeting MUC1-C also resulted in activation of the PRC1-repressed tumor suppressor genes, PTEN, CDNK2A and BIM . These findings identify a heretofore unrecognized role for MUC1-C in the epigenetic regulation of MM cells.

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

N-Myc knockdown and apigenin treatment controlled growth of malignant neuroblastoma cells having N-Myc amplification.

PubMed

Hossain, Md Motarab; Banik, Naren L; Ray, Swapan K

2013-10-15

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. © 2013 Elsevier B.V. All rights reserved.

Pan-cancer Alterations of the MYC Oncogene and Its Proximal Network across the Cancer Genome Atlas.

PubMed

Schaub, Franz X; Dhankani, Varsha; Berger, Ashton C; Trivedi, Mihir; Richardson, Anne B; Shaw, Reid; Zhao, Wei; Zhang, Xiaoyang; Ventura, Andrea; Liu, Yuexin; Ayer, Donald E; Hurlin, Peter J; Cherniack, Andrew D; Eisenman, Robert N; Bernard, Brady; Grandori, Carla

2018-03-28

Although the MYC oncogene has been implicated in cancer, a systematic assessment of alterations of MYC, related transcription factors, and co-regulatory proteins, forming the proximal MYC network (PMN), across human cancers is lacking. Using computational approaches, we define genomic and proteomic features associated with MYC and the PMN across the 33 cancers of The Cancer Genome Atlas. Pan-cancer, 28% of all samples had at least one of the MYC paralogs amplified. In contrast, the MYC antagonists MGA and MNT were the most frequently mutated or deleted members, proposing a role as tumor suppressors. MYC alterations were mutually exclusive with PIK3CA, PTEN, APC, or BRAF alterations, suggesting that MYC is a distinct oncogenic driver. Expression analysis revealed MYC-associated pathways in tumor subtypes, such as immune response and growth factor signaling; chromatin, translation, and DNA replication/repair were conserved pan-cancer. This analysis reveals insights into MYC biology and is a reference for biomarkers and therapeutics for cancers with alterations of MYC or the PMN. Copyright © 2018 The Authors. Published by Elsevier Inc. All rights reserved.

KDM4B and KDM4A promote endometrial cancer progression by regulating androgen receptor, c-myc, and p27kip1

PubMed Central

Kwan, Suet-Ying; Chen, Limo; Chen, Jin-Hong; Ying, Zuo-Lin; Zhou, Ye; Gu, Wei; Wang, Li-Hua; Cheng, Wei-Wei; Zeng, Jianfang; Wan, Xiao-Ping; Mok, Samuel C.; Wong, Kwong-Kwok; Bao, Wei

2015-01-01

Epidemiological evidence suggests that elevated androgen levels and genetic variation related to the androgen receptor (AR) increase the risk of endometrial cancer (EC). However, the role of AR in EC is poorly understood. We report that two members of the histone demethylase KDM4 family act as major regulators of AR transcriptional activityin EC. In the MFE-296 cell line, KDM4B and AR upregulate c-myc expression, while in AN3CA cells KDM4A and AR downregulate p27kip1. Additionally, KDM4B expression is positively correlated with AR expression in EC cell lines with high baseline AR expression, while KDM4A and AR expression are positively correlated in low-AR cell lines. In clinical specimens, both KDM4B and KDM4A expression are significantly higher in EC tissues than that in normal endometrium. Finally, patients with alterations in AR, KDM4B, KDM4A, and c-myc have poor overall and disease-free survival rates. Together, these findings demonstrate that KDM4B and KDM4A promote EC progression by regulating AR activity. PMID:26397136

Nac1 promotes self-renewal of embryonic stem cells through direct transcriptional regulation of c-Myc.

PubMed

Ruan, Yan; He, Jianrong; Wu, Wei; He, Ping; Tian, Yanping; Xiao, Lan; Liu, Gaoke; Wang, Jiali; Cheng, Yuda; Zhang, Shuo; Yang, Yi; Xiong, Jiaxiang; Zhao, Ke; Wan, Ying; Huang, He; Zhang, Junlei; Jian, Rui

2017-07-18

The pluripotency transcriptional network in embryonic stem cells (ESCs) is composed of distinct functional units including the core and Myc units. It is hoped that dissection of the cellular functions and interconnections of network factors will aid our understanding of ESC and cancer biology. Proteomic and genomic approaches have identified Nac1 as a member of the core pluripotency network. However, previous studies have predominantly focused on the role of Nac1 in psychomotor stimulant response and cancer pathogenesis. In this study, we report that Nac1 is a self-renewal promoting factor, but is not required for maintaining pluripotency of ESCs. Loss of function of Nac1 in ESCs results in a reduced proliferation rate and an enhanced differentiation propensity. Nac1 overexpression promotes ESC proliferation and delays ESC differentiation in the absence of leukemia inhibitory factor (LIF). Furthermore, we demonstrated that Nac1 directly binds to the c-Myc promoter and regulates c-Myc transcription. The study also revealed that the function of Nac1 in promoting ESC self-renewal appears to be partially mediated by c-Myc. These findings establish a functional link between the core and c-Myc-centered networks and provide new insights into mechanisms of stemness regulation in ESCs and cancer.

Oncogenic c-Myc-induced lymphomagenesis is inhibited non-redundantly by the p19Arf–Mdm2–p53 and RP–Mdm2–p53 pathways

PubMed Central

Meng, X; Carlson, NR; Dong, J; Zhang, Y

2016-01-01

The multifaceted oncogene c-Myc plays important roles in the development and progression of human cancer. Recent in vitro and in vivo studies have shown that the p19Arf–Mdm2–p53 and the ribosomal protein (RP)–Mdm2–p53 pathways are both essential in preventing oncogenic c-Myc-induced tumorigenesis. Disruption of each pathway individually by p19Arf deletion or by Mdm2C305F mutation, which disrupts RP-Mdm2 binding, accelerates Eμ-myc transgene-induced pre-B/B-cell lymphoma in mice at seemingly similar paces with median survival around 10 and 11 weeks, respectively, compared to 20 weeks for Eμ-myc transgenic mice. Because p19Arf can inhibit ribosomal biogenesis through its interaction with nucleophosmin (NPM/B23), RNA helicase DDX5 and RNA polymerase I transcription termination factor (TTF-I), it has been speculated that the p19Arf–Mdm2–p53 and the RP–Mdm2–p53 pathways might be a single p19Arf–RP–Mdm2–p53 pathway, in which p19Arf activates p53 by inhibiting RP biosynthesis; thus, p19Arf deletion or Mdm2C305F mutation would result in similar consequences. Here, we generated mice with concurrent p19Arf deletion and Mdm2C305F mutation and investigated the compound mice for tumorigenesis in the absence and the presence of oncogenic c-Myc overexpression. In the absence of Eμ-myc transgene, the Mdm2C305F mutation did not elicit spontaneous tumors in mice, nor did it accelerate spontaneous tumors in mice with p19Arf deletion. In the presence of Eμ-myc transgene, however, Mdm2C305F mutation significantly accelerated p19Arf deletion-induced lymphomagenesis and promoted rapid metastasis. We found that when p19Arf–Mdm2–p53 and RP–Mdm2–p53 pathways are independently disrupted, oncogenic c-Myc-induced p53 stabilization and activation is only partially attenuated. When both pathways are concurrently disrupted, however, c-Myc-induced p53 stabilization and activation are essentially obliterated. Thus, the p19Arf–Mdm2–p53 and the RP–Mdm2–p53

MYC and EGR1 synergize to trigger tumor cell death by controlling NOXA and BIM transcription upon treatment with the proteasome inhibitor bortezomib

PubMed Central

Wirth, Matthias; Stojanovic, Natasa; Christian, Jan; Paul, Mariel C.; Stauber, Roland H.; Schmid, Roland M.; Häcker, Georg; Krämer, Oliver H.; Saur, Dieter; Schneider, Günter

2014-01-01

The c-MYC (MYC afterward) oncogene is well known for driving numerous oncogenic programs. However, MYC can also induce apoptosis and this function of MYC warrants further clarification. We report here that a clinically relevant proteasome inhibitor significantly increases MYC protein levels and that endogenous MYC is necessary for the induction of apoptosis. This kind of MYC-induced cell death is mediated by enhanced expression of the pro-apoptotic BCL2 family members NOXA and BIM. Quantitative promoter-scanning chromatin immunoprecipitations (qChIP) further revealed binding of MYC to the promoters of NOXA and BIM upon proteasome inhibition, correlating with increased transcription. Both promoters are further characterized by the presence of tri-methylated lysine 4 of histone H3, marking active chromatin. We provide evidence that in our apoptosis models cell death occurs independently of p53 or ARF. Furthermore, we demonstrate that recruitment of MYC to the NOXA as well as to the BIM gene promoters depends on MYC's interaction with the zinc finger transcription factor EGR1 and an EGR1-binding site in both promoters. Our study uncovers a novel molecular mechanism by showing that the functional cooperation of MYC with EGR1 is required for bortezomib-induced cell death. This observation may be important for novel therapeutic strategies engaging the inherent pro-death function of MYC. PMID:25147211

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

Target guided synthesis using DNA nano-templates for selectively assembling a G-quadruplex binding c-MYC inhibitor

NASA Astrophysics Data System (ADS)

Panda, Deepanjan; Saha, Puja; Das, Tania; Dash, Jyotirmayee

2017-07-01

The development of small molecules is essential to modulate the cellular functions of biological targets in living system. Target Guided Synthesis (TGS) approaches have been used for the identification of potent small molecules for biological targets. We herein demonstrate an innovative example of TGS using DNA nano-templates that promote Huisgen cycloaddition from an array of azide and alkyne fragments. A G-quadruplex and a control duplex DNA nano-template have been prepared by assembling the DNA structures on gold-coated magnetic nanoparticles. The DNA nano-templates facilitate the regioselective formation of 1,4-substituted triazole products, which are easily isolated by magnetic decantation. The G-quadruplex nano-template can be easily recovered and reused for five reaction cycles. The major triazole product, generated by the G-quadruplex inhibits c-MYC expression by directly targeting the c-MYC promoter G-quadruplex. This work highlights that the nano-TGS approach may serve as a valuable strategy to generate target-selective ligands for drug discovery.

The Basic Helix-Loop-Helix Transcription Factor MYC2 Directly Represses PLETHORA Expression during Jasmonate-Mediated Modulation of the Root Stem Cell Niche in Arabidopsis[W][OA

PubMed Central

Chen, Qian; Sun, Jiaqiang; Zhai, Qingzhe; Zhou, Wenkun; Qi, Linlin; Xu, Li; Wang, Bao; Chen, Rong; Jiang, Hongling; Qi, Jing; Li, Xugang; Palme, Klaus; Li, Chuanyou

2011-01-01

The root stem cell niche, which in the Arabidopsis thaliana root meristem is an area of four mitotically inactive quiescent cells (QCs) and the surrounding mitotically active stem cells, is critical for root development and growth. We report here that during jasmonate-induced inhibition of primary root growth, jasmonate reduces root meristem activity and leads to irregular QC division and columella stem cell differentiation. Consistently, jasmonate reduces the expression levels of the AP2-domain transcription factors PLETHORA1 (PLT1) and PLT2, which form a developmentally instructive protein gradient and mediate auxin-induced regulation of stem cell niche maintenance. Not surprisingly, the effects of jasmonate on root stem cell niche maintenance and PLT expression require the functioning of MYC2/JASMONATE INSENSITIVE1, a basic helix-loop-helix transcription factor that involves versatile aspects of jasmonate-regulated gene expression. Gel shift and chromatin immunoprecipitation experiments reveal that MYC2 directly binds the promoters of PLT1 and PLT2 and represses their expression. We propose that MYC2-mediated repression of PLT expression integrates jasmonate action into the auxin pathway in regulating root meristem activity and stem cell niche maintenance. This study illustrates a molecular framework for jasmonate-induced inhibition of root growth through interaction with the growth regulator auxin. PMID:21954460

Myc-induced anchorage of the rDNA IGS region to nucleolar matrix modulates growth-stimulated changes in higher-order rDNA architecture.

PubMed

Shiue, Chiou-Nan; Nematollahi-Mahani, Amir; Wright, Anthony P H

2014-05-01

Chromatin domain organization and the compartmentalized distribution of chromosomal regions are essential for packaging of deoxyribonucleic acid (DNA) in the eukaryotic nucleus as well as regulated gene expression. Nucleoli are the most prominent morphological structures of cell nuclei and nucleolar organization is coupled to cell growth. It has been shown that nuclear scaffold/matrix attachment regions often define the base of looped chromosomal domains in vivo and that they are thereby critical for correct chromosome architecture and gene expression. Here, we show regulated organization of mammalian ribosomal ribonucleic acid genes into distinct chromatin loops by tethering to nucleolar matrix via the non-transcribed inter-genic spacer region of the ribosomal DNA (rDNA). The rDNA gene loop structures are induced specifically upon growth stimulation and are dependent on the activity of the c-Myc protein. Matrix-attached rDNA genes are hypomethylated at the promoter and are thus available for transcriptional activation. rDNA genes silenced by methylation are not recruited to the matrix. c-Myc, which has been shown to induce rDNA transcription directly, is physically associated with rDNA gene looping structures and the intergenic spacer sequence in growing cells. Such a role of Myc proteins in gene activation has not been reported previously. © 2014 The Author(s). Published by Oxford University Press [on behalf of Nucleic Acids Research].

Expression of c-Fes protein isoforms correlates with differentiation in myeloid leukemias.

PubMed

Carlson, Anne; Berkowitz, Jeanne McAdara; Browning, Damaris; Slamon, Dennis J; Gasson, Judith C; Yates, Karen E

2005-05-01

The cellular fes gene encodes a 93-kilodalton protein-tyrosine kinase (p93) that is expressed in both normal and neoplastic myeloid cells. Increased c-Fes expression is associated with differentiation in normal myeloid cells and cell lines. Our hypothesis was that primary leukemia cells would show a similar pattern of increased expression in more differentiated cells. Therefore, we compared c-Fes expression in cells with an undifferentiated, blast phenotype (acute myelogenous leukemia--AML) to cells with a differentiated phenotype (chronic myelogenous leukemia--CML). Instead of differences in p93 expression levels, we found complex patterns of c-Fes immunoreactive proteins that corresponded with differentiation in normal and leukemic myeloid cells. The "blast" pattern consisted of c-Fes immunoreactive proteins p93, p74, and p70; the "differentiated" pattern showed two additional c-Fes immunoreactive proteins, p67 and p62. Using mRNA from mouse and human cell lines, we found deletion of one or more exons in the c-fes mRNA. Those deletions predicted truncation of conserved domains (CDC15/FCH and SH2) involved in protein-protein interactions. No deletions were found, however, within the kinase domain. We infer that alternative splicing generates a family of c-Fes proteins. This may be a mechanism to direct the c-Fes kinase domain to different subcellular locations and/or substrates at specific stages of myeloid cell differentiation.

Resetting cancer stem cell regulatory nodes upon MYC inhibition.

PubMed

Galardi, Silvia; Savino, Mauro; Scagnoli, Fiorella; Pellegatta, Serena; Pisati, Federica; Zambelli, Federico; Illi, Barbara; Annibali, Daniela; Beji, Sara; Orecchini, Elisa; Alberelli, Maria Adele; Apicella, Clara; Fontanella, Rosaria Anna; Michienzi, Alessandro; Finocchiaro, Gaetano; Farace, Maria Giulia; Pavesi, Giulio; Ciafrè, Silvia Anna; Nasi, Sergio

2016-12-01

MYC deregulation is common in human cancer and has a role in sustaining the aggressive cancer stem cell populations. MYC mediates a broad transcriptional response controlling normal biological programmes, but its activity is not clearly understood. We address MYC function in cancer stem cells through the inducible expression of Omomyc-a MYC-derived polypeptide interfering with MYC activity-taking as model the most lethal brain tumour, glioblastoma. Omomyc bridles the key cancer stemlike cell features and affects the tumour microenvironment, inhibiting angiogenesis. This occurs because Omomyc interferes with proper MYC localization and itself associates with the genome, with a preference for sites occupied by MYC This is accompanied by selective repression of master transcription factors for glioblastoma stemlike cell identity such as OLIG2, POU3F2, SOX2, upregulation of effectors of tumour suppression and differentiation such as ID4, MIAT, PTEN, and modulation of the expression of microRNAs that target molecules implicated in glioblastoma growth and invasion such as EGFR and ZEB1. Data support a novel view of MYC as a network stabilizer that strengthens the regulatory nodes of gene expression networks controlling cell phenotype and highlight Omomyc as model molecule for targeting cancer stem cells. © 2016 The Authors.

Cloning and expression of BpMYC4 and BpbHLH9 genes and the role of BpbHLH9 in triterpenoid synthesis in birch.

PubMed

Yin, Jing; Li, Xin; Zhan, Yaguang; Li, Ying; Qu, Ziyue; Sun, Lu; Wang, Siyao; Yang, Jie; Xiao, Jialei

2017-11-21

Birch (Betula platyphylla Suk.) contains triterpenoids with anti-HIV and anti-tumor pharmacological activities. However, the natural abundance of these triterpenoids is low, and their chemical synthesis is costly. Transcription factors have the ability to regulate the metabolite pathways of triterpenoids via multi-gene control, thereby improving metabolite yield. Thus, transcription factors have the potential to facilitate the production of birch triterpenoids. Plant bHLH (basic helix-loop-helix) transcription factors play important roles in stress response and secondary metabolism. In this study, we cloned two genes, BpMYC4 and BpbHLH9, that encode bHLH transcription factors in Betula platyphylla Suk. The open reading frame (ORF) of BpMYC4 was 1452 bp and encoded 483 amino acids, while the ORF of BpbHLH9 was 1140 bp and encoded 379 amino acids. The proteins of BpMYC4 and BpbHLH9 were localized in the cell membrane and nucleus. The tissue-specific expression patterns revealed that BpMYC4 expression in leaves was similar to that in the stem and higher than in the roots. The expression of BpbHLH9 was higher in the leaves than in the root and stem. The expressions of BpMYC4 and BpbHLH9 increased after treatment with abscisic acid, methyl jasmonate, and gibberellin and decreased after treatment with ethephon. The promoters of BpMYC4 and BpbHLH9 were isolated using a genome walking approach, and 900-bp and 1064-bp promoter sequences were obtained for BpMYC4 and BpbHLH9, respectively. The ORF of BpbHLH9 was ligated into yeast expression plasmid pYES3 and introduced into INVScl and INVScl1-pYES2-SS yeast strains. The squalene and total triterpenoid contents in the different INVScl1 transformants decreased in the following order INVScl1-pYES-SS-bHLH9 > INVScl1-pYES3-bHLH9 > INVScl1-pYES2- BpSS > INVScl-pYES2. In BpbHLH9 transgenic birch, the relative expression of the genes that encodes for enzymes critical for triterpenoid synthesis showed a different level of up

Targeting oncogenic Myc as a strategy for cancer treatment.

PubMed

Chen, Hui; Liu, Hudan; Qing, Guoliang

2018-01-01

The MYC family oncogene is deregulated in >50% of human cancers, and this deregulation is frequently associated with poor prognosis and unfavorable patient survival. Myc has a central role in almost every aspect of the oncogenic process, orchestrating proliferation, apoptosis, differentiation, and metabolism. Although Myc inhibition would be a powerful approach for the treatment of many types of cancers, direct targeting of Myc has been a challenge for decades owing to its "undruggable" protein structure. Hence, alternatives to Myc blockade have been widely explored to achieve desirable anti-tumor effects, including Myc/Max complex disruption, MYC transcription and/or translation inhibition, and Myc destabilization as well as the synthetic lethality associated with Myc overexpression. In this review, we summarize the latest advances in targeting oncogenic Myc, particularly for cancer therapeutic purposes.

MYC gene amplification is a rare event in atypical fibroxanthoma and pleomorphic dermal sarcoma

PubMed Central

Bach, Marisa; Kind, Peter; Helbig, Doris; Quaas, Alexander; Utikal, Jochen; Marx, Alexander; Gaiser, Maria Rita

2018-01-01

Atypical fibroxanthoma (AFX) and pleomorphic dermal sarcoma (PDS) are rare malignancies typically occurring in elderly patients and predominantly located in skin regions exposed to UV-light. Thus, a role of UV-radiation-induced damage for AFX and PDS tumorigenesis has been postulated. MYC gene amplification has been demonstrated as a distinctive feature of radiation-induced angiosarcoma. In order to investigate whether chronic exposure to UV-light might also lead to MYC copy number changes, 51 AFX and 24 PDS samples were retrospectively analyzed for MYC amplification by fluorescence in situ hybridization using a MYC and a CEP8 gene probe. Of the 44 analyzable AFX samples, one case showed MYC amplification (defined as a MYC/CEP8 ratio ≥2.0), whereas 13 cases demonstrated low level copy number gains (defined as MYC/CEP8 ratio ≥ 1.2−< 2.0). MYC amplification was seen in an AFX sample of extraordinary tumor thickness of 17.5 mm (vs. median 3.25 mm for all samples). Of the 24 PDS cases, five specimen demonstrated MYC low level copy number gains. Immunohistochemically, neither the AFX nor the PDS cases showed MYC protein expression. In summary, these findings rule out that MYC amplification is a major genetic driver in the process of AFX or PDS tumorigenesis. However, MYC amplification may occur as a late event during AFX development and hence might only be detectable in advanced, thick lesions. PMID:29765529

MYC gene amplification is a rare event in atypical fibroxanthoma and pleomorphic dermal sarcoma.

PubMed

Gaiser, Timo; Hirsch, Daniela; Orouji, Azadeh; Bach, Marisa; Kind, Peter; Helbig, Doris; Quaas, Alexander; Utikal, Jochen; Marx, Alexander; Gaiser, Maria Rita

2018-04-20

Atypical fibroxanthoma (AFX) and pleomorphic dermal sarcoma (PDS) are rare malignancies typically occurring in elderly patients and predominantly located in skin regions exposed to UV-light. Thus, a role of UV-radiation-induced damage for AFX and PDS tumorigenesis has been postulated. MYC gene amplification has been demonstrated as a distinctive feature of radiation-induced angiosarcoma. In order to investigate whether chronic exposure to UV-light might also lead to MYC copy number changes, 51 AFX and 24 PDS samples were retrospectively analyzed for MYC amplification by fluorescence in situ hybridization using a MYC and a CEP8 gene probe. Of the 44 analyzable AFX samples, one case showed MYC amplification (defined as a MYC /CEP8 ratio ≥2.0), whereas 13 cases demonstrated low level copy number gains (defined as MYC /CEP8 ratio ≥ 1.2-< 2.0). MYC amplification was seen in an AFX sample of extraordinary tumor thickness of 17.5 mm (vs. median 3.25 mm for all samples). Of the 24 PDS cases, five specimen demonstrated MYC low level copy number gains. Immunohistochemically, neither the AFX nor the PDS cases showed MYC protein expression. In summary, these findings rule out that MYC amplification is a major genetic driver in the process of AFX or PDS tumorigenesis. However, MYC amplification may occur as a late event during AFX development and hence might only be detectable in advanced, thick lesions.

Constitutive androstane receptor activation evokes the expression of glycolytic genes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yarushkin, Andrei A.; Kazantseva, Yuliya A.; Prokopyeva, Elena A.

It is well-known that constitutive androstane receptor (CAR) activation by 1,4-bis[2-(3,5-dichloropyridyloxy)]benzene (TCPOBOP) increases the liver-to-body weight ratio. CAR-mediated liver growth is correlated with increased expression of the pleiotropic transcription factor cMyc, which stimulates cell cycle regulatory genes and drives proliferating cells into S phase. Because glycolysis supports cell proliferation and cMyc is essential for the activation of glycolytic genes, we hypothesized that CAR-mediated up-regulation of cMyc in mouse livers might play a role in inducing the expression of glycolytic genes. The aim of the present study was to examine the effect of long-term CAR activation on glycolytic genes in amore » mouse model not subjected to metabolic stress. We demonstrated that long-term CAR activation by TCPOBOP increases expression of cMyc, which was correlated with reduced expression of gluconeogenic genes and up-regulation of glucose transporter, glycolytic and mitochondrial pyruvate metabolising genes. These changes in gene expression after TCPOBOP treatment were strongly correlated with changes in levels of glycolytic intermediates in mouse livers. Moreover, we demonstrated a significant positive regulatory effect of TCPOBOP-activated CAR on both mRNA and protein levels of Pkm2, a master regulator of glucose metabolism and cell proliferation. Thus, our findings provide evidence to support the conclusion that CAR activation initiates a transcriptional program that facilitates the coordinated metabolic activities required for cell proliferation. - Highlights: • CAR-mediated liver growth is correlated with increased expression of cMyc. • CAR activation increased the expression of glycolytic genes in mouse livers. • CAR activation increased the level of Pkm2 in mouse livers.« less

Mechanisms for c-myc Induced Mouse Mammary Gland Carcinogenesis and for the Synergistic Role of TGF(alpha) in the Process

DTIC Science & Technology

2001-07-01

1997 Glucose deprivation- induced cytotoxicity in drug resistant genomic status of the c-myc locus in infiltrating ductal human breast carcinoma MCF-7...AD Award Number: DAMD17-00-1-0270 TITLE: Mechanisms for c-myc Induced Mouse Mammary Gland Carcinogenesis and for the Synergistic Role of TGFOX in the...AND SUBTITLE 5. FUNDING NUMBERS Mechanisms for c-myc Induced Mouse Mammary Gland DAMD17-00-1-0270 Carcinogenesis and for the Synergistic Role of TGFa in

Double-hit or dual expression of MYC and BCL2 in primary cutaneous large B-cell lymphomas.

PubMed

Menguy, Sarah; Frison, Eric; Prochazkova-Carlotti, Martina; Dalle, Stephane; Dereure, Olivier; Boulinguez, Serge; Dalac, Sophie; Machet, Laurent; Ram-Wolff, Caroline; Verneuil, Laurence; Gros, Audrey; Vergier, Béatrice; Beylot-Barry, Marie; Merlio, Jean-Philippe; Pham-Ledard, Anne

2018-03-26

In nodal diffuse large B-cell lymphoma, the search for double-hit with MYC and BCL2 and/or BCL6 rearrangements or for dual expression of BCL2 and MYC defines subgroups of patients with altered prognosis that has not been evaluated in primary cutaneous large B-cell lymphoma. Our objectives were to assess the double-hit and dual expressor status in a cohort of 44 patients with primary cutaneous large B-cell lymphoma according to the histological subtype and to evaluate their prognosis relevance. The 44 cases defined by the presence of more than 80% of large B-cells in the dermis corresponded to 21 primary cutaneous follicle centre lymphoma with large cell morphology and 23 primary cutaneous diffuse large B-cell lymphoma, leg type. Thirty-one cases (70%) expressed BCL2 and 29 (66%) expressed MYC. Dual expressor profile was observed in 25 cases (57%) of either subtypes (n = 6 or n = 19, respectively). Only one primary cutaneous follicle centre lymphoma, large-cell case had a double-hit status (2%). Specific survival was significantly worse in primary cutaneous diffuse large B-cell lymphoma, leg type than in primary cutaneous follicle centre lymphoma, large cell (p = 0.021) and for the dual expressor primary cutaneous large B-cell lymphoma group (p = 0.030). Both overall survival and specific survival were worse for patients belonging to the dual expressor primary cutaneous diffuse large B-cell lymphoma, leg type subgroup (p = 0.001 and p = 0.046, respectively). Expression of either MYC and/or BCL2 negatively impacted overall survival (p = 0.017 and p = 0.018 respectively). As the differential diagnosis between primary cutaneous follicle centre lymphoma, large cell and primary cutaneous diffuse large B-cell lymphoma, leg type has a major impact on prognosis, dual-expression of BCL2 and MYC may represent a new diagnostic criterion for primary cutaneous diffuse large B-cell lymphoma, leg type subtype and further identifies patients with

Quantitative Expression and Co-Localization of Wnt Signalling Related Proteins in Feline Squamous Cell Carcinoma

PubMed Central

Marote, Georgina; Abramo, Francesca; McKay, Jenny; Thomson, Calum; Beltran, Mariana; Millar, Michael; Priestnall, Simon; Dobson, Jane; Costantino-Casas, Fernando; Petrou, Terry; McGonnell, Imelda M.; Davies, Anthony J.; Weetman, Malcolm; Garden, Oliver A.; Masters, John R.; Thrasivoulou, Christopher; Ahmed, Aamir

2016-01-01

Feline oral squamous cell carcinoma (FOSCC) is an aggressive neoplasm in cats. Little is known about the possible molecular mechanisms that may be involved in the initiation, maintenance and progression of FOSCC. Wnt signalling is critical in development and disease, including many mammalian cancers. In this study, we have investigated the expression of Wnt signalling related proteins using quantitative immunohistochemical techniques on tissue arrays. We constructed tissue arrays with 58 individual replicate tissue samples. We tested for the expression of four key Wnt/ß-catenin transcription targets, namely Cyclin D1 (CCND1 or CD1), FRA1, c-Myc and MMP7. All antibodies showed cross reactivity in feline tissue except MMP7. Quantitative immunohistochemical analysis of single proteins (expressed as area fraction / amount of tissue for normal vs tumor, mean ± SE) showed that the expression of CD1 (3.9 ± 0.5 vs 12.2 ± 0.9), FRA1 (5.5 ± 0.6 vs 16.8 ± 1.1) and c-Myc (5.4 ± 0.5 vs 12.5 ± 0.9) was increased in FOSCC tissue by 2.3 to 3 fold compared to normal controls (p<0.0001). By using a multilabel, quantitative fluorophore technique we further investigated if the co-localization of these proteins (all transcription factors) with each other and in the nucleus (stained with 4',6-diamidino-2-phenylindole, DAPI) was altered in FOSCC compared to normal tissue. The global intersection coefficients, a measure of the proximity of two fluorophore labeled entities, showed that there was a significant change (p < 0.01) in the co-localization for all permutations (e.g. CD1/FRA1 etc), except for the nuclear localization of CD1. Our results show that putative targets of Wnt signalling transcription are up-regulated in FOSCC with alterations in the co-localization of these proteins and could serve as a useful marker for the disease. PMID:27559731

c-Myc plays a key role in TADs-induced apoptosis and cell cycle arrest in human hepatocellular carcinoma cells

PubMed Central

Zhang, Dongdong; Qi, Junpeng; Liu, Rui; Dai, Bingling; Ma, Weina; Zhan, Yingzhuan; Zhang, Yanmin

2015-01-01

Cancer cell growth is complicated progression which is regulated and controlled by multiple factors including cell cycle, migration and apoptosis. In present study, we report that TADs, a novel derivative of taspine, has an essential role in resisting hepatocellular carcinoma growth (including arrest cell cycle) and migration, and inducing cell apoptosis. Our findings demonstrated that the TADs showed good inhibition on the hepatoma cell growth and migration, and good action on apoptosis induction. Using genome-wide microarray analysis, we found the down-regulated growth and apoptosis factors, and selected down-regulated genes were confirmed by Western blot. Knockdown of a checkpoint c-Myc by siRNA significantly attenuated tumor inhibition and apoptosis effects of TADs. Moreover, our results indicated TADs could simultaneously increase cyclin D1 protein levels and decrease amount of cyclin E, cyclin B1 and cdc2 of the cycle proteins, and also TADs reduced Bcl-2 expression, and upregulated Bad, Bak and Bax activities. In conclusion, these results illustrated that TADs is a key factor in growth and apoptosis signaling inhibitor, has potential in cancer therapy. PMID:26045987

c-Myc plays a key role in TADs-induced apoptosis and cell cycle arrest in human hepatocellular carcinoma cells.

PubMed

Zhang, Dongdong; Qi, Junpeng; Liu, Rui; Dai, Bingling; Ma, Weina; Zhan, Yingzhuan; Zhang, Yanmin

2015-01-01

Cancer cell growth is complicated progression which is regulated and controlled by multiple factors including cell cycle, migration and apoptosis. In present study, we report that TADs, a novel derivative of taspine, has an essential role in resisting hepatocellular carcinoma growth (including arrest cell cycle) and migration, and inducing cell apoptosis. Our findings demonstrated that the TADs showed good inhibition on the hepatoma cell growth and migration, and good action on apoptosis induction. Using genome-wide microarray analysis, we found the down-regulated growth and apoptosis factors, and selected down-regulated genes were confirmed by Western blot. Knockdown of a checkpoint c-Myc by siRNA significantly attenuated tumor inhibition and apoptosis effects of TADs. Moreover, our results indicated TADs could simultaneously increase cyclin D1 protein levels and decrease amount of cyclin E, cyclin B1 and cdc2 of the cycle proteins, and also TADs reduced Bcl-2 expression, and upregulated Bad, Bak and Bax activities. In conclusion, these results illustrated that TADs is a key factor in growth and apoptosis signaling inhibitor, has potential in cancer therapy.

Jasmonate signalling pathway in strawberry: Genome-wide identification, molecular characterization and expression of JAZs and MYCs during fruit development and ripening.

PubMed

Garrido-Bigotes, Adrián; Figueroa, Nicolás E; Figueroa, Pablo M; Figueroa, Carlos R

2018-01-01

Jasmonates (JAs) are signalling molecules involved in stress responses, development and secondary metabolism biosynthesis, although their roles in fleshy-fruit development and ripening processes are not well known. In strawberry fruit, it has been proposed that JAs could regulate the early development through the activation of the JAs biosynthesis. Moreover, it has been reported that JA treatment increases anthocyanin content in strawberry fruit involving the bioactive jasmonate biosynthesis. Nevertheless, JA signalling pathway, of which main components are the COI1-JAZ co-receptor and the MYC transcription factors (TFs), has not been characterized in strawberry until now. Here we identified and characterized the woodland strawberry (Fragaria vesca) JAZ and MYC genes as well as studied their expression during development and ripening stages in commercial strawberry (Fragaria × ananassa) fruit. We described twelve putative JAZ proteins and two MYC TFs, which showed high conservation with respect to their orthologs in Arabidopsis thaliana and in other fleshy-fruit species such as Malus × domestica, Vitis vinifera and Solanum lycopersicum as revealed by gene synteny and phylogenetic analyses. Noteworthy, their expression levels exhibited a significant decrease from fruit development to ripening stages in F. × ananassa, along with others of the JA signalling-related genes such as FaNINJA and FaJAMs, encoding for negative regulators of JA responses. Moreover, we found that main JA signalling-related genes such as FaMYC2, and FaJAZ1 are promptly induced by JA treatment at early times in F. × ananassa fruit. These results suggest the conservation of the canonical JA signalling pathway in strawberry and a possible role of this pathway in early strawberry fruit development, which also correlates negatively with the beginning of the ripening process.

Jasmonate signalling pathway in strawberry: Genome-wide identification, molecular characterization and expression of JAZs and MYCs during fruit development and ripening

PubMed Central

Figueroa, Nicolás E.; Figueroa, Pablo M.

2018-01-01

Jasmonates (JAs) are signalling molecules involved in stress responses, development and secondary metabolism biosynthesis, although their roles in fleshy-fruit development and ripening processes are not well known. In strawberry fruit, it has been proposed that JAs could regulate the early development through the activation of the JAs biosynthesis. Moreover, it has been reported that JA treatment increases anthocyanin content in strawberry fruit involving the bioactive jasmonate biosynthesis. Nevertheless, JA signalling pathway, of which main components are the COI1-JAZ co-receptor and the MYC transcription factors (TFs), has not been characterized in strawberry until now. Here we identified and characterized the woodland strawberry (Fragaria vesca) JAZ and MYC genes as well as studied their expression during development and ripening stages in commercial strawberry (Fragaria × ananassa) fruit. We described twelve putative JAZ proteins and two MYC TFs, which showed high conservation with respect to their orthologs in Arabidopsis thaliana and in other fleshy-fruit species such as Malus × domestica, Vitis vinifera and Solanum lycopersicum as revealed by gene synteny and phylogenetic analyses. Noteworthy, their expression levels exhibited a significant decrease from fruit development to ripening stages in F. × ananassa, along with others of the JA signalling-related genes such as FaNINJA and FaJAMs, encoding for negative regulators of JA responses. Moreover, we found that main JA signalling-related genes such as FaMYC2, and FaJAZ1 are promptly induced by JA treatment at early times in F. × ananassa fruit. These results suggest the conservation of the canonical JA signalling pathway in strawberry and a possible role of this pathway in early strawberry fruit development, which also correlates negatively with the beginning of the ripening process. PMID:29746533

AMPK inhibits MTDH expression via GSK3β and SIRT1 activation: potential role in triple negative breast cancer cell proliferation.

PubMed

Gollavilli, Paradesi Naidu; Kanugula, Anantha Koteswararao; Koyyada, Rajeswari; Karnewar, Santosh; Neeli, Praveen Kumar; Kotamraju, Srigiridhar

2015-10-01

Recent studies have highlighted the involvement of metadherin (MTDH), an oncogenic protein, in promoting cancer progression, metastasis and chemoresistance in many cancers including mammary carcinomas. However, the molecular regulation of MTDH is still not completely understood. In this study we document that AMP activated protein kinase (AMPK) activation-induced anti-proliferative effects are, in part, mediated by inhibiting MTDH expression in MDA-MB-231 and BT-549 triple negative breast cancer (TNBC) cells. 5-Aminoimidazole-4-carboxamide ribonucleotide (AICAR), an AMPK activator, caused growth arrest, inhibition of migration and invasion of TNBC cells. Intriguingly, AICAR or metformin treatment resulted in significant downregulation of MTDH expression via inhibiting c-Myc expression. In contrast, treatment of cells with compound C, an inhibitor of AMPK, increased both c-Myc and MTDH expressions in TNBC cells. Also, AMPK activation caused increased glycogen synthase kinase 3β (GSK3β) activity by inhibiting the inactive phosphorylation at Ser9, on the one hand, and activation of sirtuin1 (SIRT1) by inhibiting Ser47 phosphorylation, as evidenced by deacetylation of p53, on the other hand. Moreover, AMPK-induced GSK3β and SIRT1 activities were found to be responsible for inhibiting c-Myc-mediated upregulation of MTDH, as LiCl (an inhibitor of GSK3β) and EX-527 (an inhibitor of SIRT1) reversed AICAR-mediated downregulation of c-Myc and MTDH expressions. Similar results were observed with siSIRT1 treatment. Furthermore, AICAR and EX-527 treatments caused increased cell death under MTDH-depleted conditions. Finally, we uncovered a novel regulation of MTDH expression and showed that AMPK activation by inducing GSK3β and SIRT1 downregulates MTDH expression via inhibiting c-Myc in TNBC cells. © 2015 FEBS.

A benzindole substituted carbazole cyanine dye: a novel targeting fluorescent probe for parallel c-myc G-quadruplexes.

PubMed

Lin, Dayong; Fei, Xuening; Gu, Yingchun; Wang, Cuihong; Tang, Yalin; Li, Ran; Zhou, Jianguo

2015-08-21

Many organic ligands were synthesized to recognize G-quadruplexes. However, different kinds of G-quadruplexes (G4s) possess different structures and functions. Therefore, selective recognition of certain types of G4s is important for the study of G4s. In this paper, a novel cyanine dye, 3-(2-(4-vinylpyridine))-6-(2-((1-(4-sulfobutyl))-3,3-dimethyl-2-vinylbenz[e]indole)-9-ethyl-carbazole (9E PBIC), composed of benzindole and carbazole was designed and synthesised. The studies on UV-vis and fluorescence properties of the dye with different DNA forms showed that the dye exhibits almost no fluorescence under aqueous buffer conditions, but it increased over 100 fold in the presence of c-myc G4 and 10-30 fold in the presence of other G4s, while little in the presence of single/double-stranded DNA, indicating that it has excellent selectivity to c-myc 2345 G4. For the binding studies the dye is interacted with the c-myc 2345 G-quadruplex by using the end-stack binding model. It can be said that the dye is an excellent targeting fluorescent probe for c-myc G-quadruplexes.

Characterization of pancreatic lesions from MT-tgf alpha, Ela-myc and MT-tgf alpha/Ela-myc single and double transgenic mice.

PubMed

Liao, Dezhong Joshua; Wang, Yong; Wu, Jiusheng; Adsay, Nazmi Volkan; Grignon, David; Khanani, Fayyaz; Sarkar, Fazlul H

2006-07-05

In order to identify good animal models for investigating therapeutic and preventive strategies for pancreatic cancer, we analyzed pancreatic lesions from several transgenic models and made a series of novel findings. Female MT-tgf alpha mice of the MT100 line developed pancreatic proliferation, acinar-ductal metaplasia, multilocular cystic neoplasms, ductal adenocarcinomas and prominent fibrosis, while the lesions in males were less severe. MT-tgf alpha-ES transgenic lines of both sexes developed slowly progressing lesions that were similar to what was seen in MT100 males. In both MT100 and MT-tgf alpha-ES lines, TGF alpha transgene was expressed mainly in proliferating ductal cells. Ela-myc transgenic mice with a mixed C57BL/6, SJL and FVB genetic background developed pancreatic tumors at 2-7 months of age, and half of the tumors were ductal adenocarcinomas, similar to what was reported originally by Sandgren et al 1. However, in 20% of the mice, the tumors metastasized to the liver. MT100/Ela-myc and MT-tgf alpha-ES/Ela-myc double transgenic mice developed not only acinar carcinomas and mixed carcinomas as previously reported but also various ductal-originated lesions, including multilocular cystic neoplasms and ductal adenocarcinomas. The double transgenic tumors were more malignant and metastasized to the liver at a higher frequency (33%) compared with the Ela-myc tumors. Sequencing of the coding region of p16ink4, k-ras and Rb cDNA in small numbers of pancreatic tumors did not identify mutations. The short latency for tumor development, the variety of tumor morphology and the liver metastases seen in Ela-myc and MT-tgf alpha/Ela-myc mice make these animals good models for investigating new therapeutic and preventive strategies for pancreatic cancer.

Dynamic epigenetic regulation of glioblastoma tumorigenicity through LSD1 modulation of MYC expression

PubMed Central

Kozono, David; Li, Jie; Nitta, Masayuki; Sampetrean, Oltea; Gonda, David; Kushwaha, Deepa S.; Merzon, Dmitry; Ramakrishnan, Valya; Zhu, Shan; Zhu, Kaya; Matsui, Hiroko; Harismendy, Olivier; Hua, Wei; Mao, Ying; Kwon, Chang-Hyuk; Saya, Hideyuki; Nakano, Ichiro; Pizzo, Donald P.; VandenBerg, Scott R.; Chen, Clark C.

2015-01-01

The available evidence suggests that the lethality of glioblastoma is driven by small subpopulations of cells that self-renew and exhibit tumorigenicity. It remains unclear whether tumorigenicity exists as a static property of a few cells or as a dynamically acquired property. We used tumor-sphere and xenograft formation as assays for tumorigenicity and examined subclones isolated from established and primary glioblastoma lines. Our results indicate that glioblastoma tumorigenicity is largely deterministic, yet the property can be acquired spontaneously at low frequencies. Further, these dynamic transitions are governed by epigenetic reprogramming through the lysine-specific demethylase 1 (LSD1). LSD depletion increases trimethylation of histone 3 lysine 4 at the avian myelocytomatosis viral oncogene homolog (MYC) locus, which elevates MYC expression. MYC, in turn, regulates oligodendrocyte lineage transcription factor 2 (OLIG2), SRY (sex determining region Y)-box 2 (SOX2), and POU class 3 homeobox 2 (POU3F2), a core set of transcription factors required for reprogramming glioblastoma cells into stem-like states. Our model suggests epigenetic regulation of key transcription factors governs transitions between tumorigenic states and provides a framework for glioblastoma therapeutic development. PMID:26159421

Nutrient deprivation-related OXPHOS/glycolysis interconversion via HIF-1α/C-MYC pathway in U251 cells.

PubMed

Liu, Zhongjian; Sun, Yang; Tan, Shirui; Liu, Liang; Hu, Suqiong; Huo, Hongyu; Li, Meizhang; Cui, Qinghua; Yu, Min

2016-05-01

Although the Warburg effect is a dominant metabolic phenotype observed in cancers, the metabolic changes and adaptation occurring in tumors have been demonstrated to extend beyond the Warburg effect and thus considered a secondary effect to the transformation process of carcinogenesis, including nutritional deficiencies. However, the role of nutritional deficiencies in this metabolic reprogramming (e. g., oxidative phosphorylation (OXPHOS)/glycolysis interconversion) is not completely known yet. Here, we showed that under regular culture condition, the proliferation of U251 cells, but not other tumor cell lines, preferentially performed the Warburg effect and was remarkably inhibited by oxamic acid which can inhibit the activity of lactate dehydrogenase (LDH); whereas under serum starvation, glycolysis was depressed, tricarboxylic acid cycle (TCA) was enhanced, and the activity of OXPHOS was reinforced to maintain cellular ATP content in a high level, but interestingly, we observed a decreased expression of reactive oxygen species (ROS). Moreover, the upregulated activity of mitochondrial complex I was confirmed by Western blots and showed that the mitochondrial-related protein, NDUFA9, NDUFB8, ND1, and VDAC1 were remarkably increased after serum starved. Mechanistically, nutritional deficiencies could reduce hypoxia-inducible factor α (HIF-1α) protein expression to increase C-MYC protein level, which in turn increased nuclear respiratory factor 1 (NRF1) and mitochondrial transcription factor A (TFAM) transcription to enhance the activity of OXPHOS, suggesting that metabolic reprogramming by the changes of microenvironment during the carcinogenesis can provide some novel therapeutic clues to traditional cancer treatments.

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.

A credit-card library approach for disrupting protein-protein interactions.

PubMed

Xu, Yang; Shi, Jin; Yamamoto, Noboru; Moss, Jason A; Vogt, Peter K; Janda, Kim D

2006-04-15

Protein-protein interfaces are prominent in many therapeutically important targets. Using small organic molecules to disrupt protein-protein interactions is a current challenge in chemical biology. An important example of protein-protein interactions is provided by the Myc protein, which is frequently deregulated in human cancers. Myc belongs to the family of basic helix-loop-helix leucine zipper (bHLH-ZIP) transcription factors. It is biologically active only as heterodimer with the bHLH-ZIP protein Max. Herein, we report a new strategy for the disruption of protein-protein interactions that has been corroborated through the design and synthesis of a small parallel library composed of 'credit-card' compounds. These compounds are derived from a planar, aromatic scaffold and functionalized with four points of diversity. From a 285 membered library, several hits were obtained that disrupted the c-Myc-Max interaction and cellular functions of c-Myc. The IC50 values determined for this small focused library for the disruption of Myc-Max dimerization are quite potent, especially since small molecule antagonists of protein-protein interactions are notoriously difficult to find. Furthermore, several of the compounds were active at the cellular level as shown by their biological effects on Myc action in chicken embryo fibroblast assays. In light of our findings, this approach is considered a valuable addition to the armamentarium of new molecules being developed to interact with protein-protein interfaces. Finally, this strategy for disrupting protein-protein interactions should prove applicable to other families of proteins.

The Use of Protein-DNA, Chromatin Immunoprecipitation, and Transcriptome Arrays to Describe Transcriptional Circuits in the Dehydrated Male Rat Hypothalamus

PubMed Central

Qiu, Jing; Kleineidam, Anna; Gouraud, Sabine; Yao, Song Tieng; Greenwood, Mingkwan; Hoe, See Ziau; Hindmarch, Charles

2014-01-01

The supraoptic nucleus (SON) of the hypothalamus is responsible for maintaining osmotic stability in mammals through its elaboration of the antidiuretic hormone arginine vasopressin. Upon dehydration, the SON undergoes a function-related plasticity, which includes remodeling of morphology, electrical properties, and biosynthetic activity. This process occurs alongside alterations in steady state transcript levels, which might be mediated by changes in the activity of transcription factors. In order to identify which transcription factors might be involved in changing patterns of gene expression, an Affymetrix protein-DNA array analysis was carried out. Nuclear extracts of SON from dehydrated and control male rats were analyzed for binding to the 345 consensus DNA transcription factor binding sequences of the array. Statistical analysis revealed significant changes in binding to 26 consensus elements, of which EMSA confirmed increased binding to signal transducer and activator of transcription (Stat) 1/Stat3, cellular Myelocytomatosis virus-like cellular proto-oncogene (c-Myc)-Myc-associated factor X (Max), and pre-B cell leukemia transcription factor 1 sequences after dehydration. Focusing on c-Myc and Max, we used quantitative PCR to confirm previous transcriptomic analysis that had suggested an increase in c-Myc, but not Max, mRNA levels in the SON after dehydration, and we demonstrated c-Myc- and Max-like immunoreactivities in SON arginine vasopressin-expressing cells. Finally, by comparing new data obtained from Roche-NimbleGen chromatin immunoprecipitation arrays with previously published transcriptomic data, we have identified putative c-Myc target genes whose expression changes in the SON after dehydration. These include known c-Myc targets, such as the Slc7a5 gene, which encodes the L-type amino acid transporter 1, ribosomal protein L24, histone deactylase 2, and the Rat sarcoma proto-oncogene (Ras)-related nuclear GTPase. PMID:25144923

Mucin1 shifts Smad3 signaling from the tumor-suppressive pSmad3C/p21(WAF1) pathway to the oncogenic pSmad3L/c-Myc pathway by activating JNK in human hepatocellular carcinoma cells.

PubMed

Li, Qiongshu; Liu, Guomu; Yuan, Hongyan; Wang, Juan; Guo, Yingying; Chen, Tanxiu; Zhai, Ruiping; Shao, Dan; Ni, Weihua; Tai, Guixiang

2015-02-28

Mucin1 (MUC1) is a transmembrane glycoprotein that acts as an oncogene in human hepatic tumorigenesis. Hepatocellular carcinoma (HCC) cells often gain advantage by reducing the tumor-suppressive activity of transforming growth factor beta (TGF-β) together with stimulation of its oncogenic activity as in MUC1 expressing HCC cells; however, molecular mechanisms remain largely unknown. Type I TGF-β receptor (TβRI) and c-Jun NH2-terminal kinase (JNK) differentially phosphorylate Smad3 mediator to create 2 phosphorylated forms: COOH-terminally phosphorylated Smad3 (pSmad3C) and linker-phosphorylated Smad3 (pSmad3L). Here, we report that MUC1 overexpression in HCC cell lines suppresses TβRI-mediated pSmad3C signaling which involves growth inhibition by up-regulating p21(WAF1). Instead, MUC1 directly activates JNK to stimulate oncogenic pSmad3L signaling, which fosters cell proliferation by up-regulating c-Myc. Conversely, MUC1 gene silencing in MUC1 expressing HCC cells results in preserved tumor-suppressive function via pSmad3C, while eliminating pSmad3L-mediated oncogenic activity both in vitro and in vivo. In addition, high correlation between MUC1 and pSmad3L/c-Myc but not pSmad3C/p21(WAF1) expression was observed in HCC tissues from patients. Collectively, these results indicate that MUC1 shifts Smad3 signaling from a tumor-suppressive pSmad3C/p21(WAF1) to an oncogenic pSmad3L/c-Myc pathway by directly activating JNK in HCC cells, suggesting that MUC1 is an important target for HCC therapy.

The novel protein C3orf43 accelerates hepatocyte proliferation.

PubMed

Zhang, Chunyan; Chang, Cuifang; Li, Deming; Zhang, Fuchun; Xu, Cunshuan

2017-01-01

Our previous study found that single-pass membrane protein with coiled-coil domains 1 (C3orf43; XM_006248472.3) was significantly upregulated in the proliferative phase during liver regeneration. This indicates that C3orf43 plays a vital role in liver cell proliferation. However, its physiological functions remains unclear. The expressions of C3orf43 in BRL-3A cells transfected with C3orf43-siRNA (C3-siRNA) or overexpressing the vector plasmid pCDH-C3orf43 (pCDH-C3) were measured via RT-qPCR and western blot. Cell growth and proliferation were determined using MTT and flow cytometry. Cell proliferation-related gene expression was measured using RT-qPCR and western blot. It was found that upregulation of C3orf43 by pCDH-C3 promoted hepatocyte proliferation, and inhibition of C3orf43 by C3-siRNA led to the reduction of cell proliferation. The results of qRT-PCR and western blot assay showed that the C3-siRNA group downregulated the expression of cell proliferation-related genes like JUN, MYC, CCND1 and CCNA2, and the pCDH-C3 group upregulated the expression of those genes. These findings reveal that C3orf43 may contribute to hepatocyte proliferation and may have the potential to promote liver repair and regeneration.

Canonical Initiation Factor Requirements of the Myc Family of Internal Ribosome Entry Segments▿ †

PubMed Central

Spriggs, Keith A.; Cobbold, Laura C.; Jopling, Catherine L.; Cooper, Rebecca E.; Wilson, Lindsay A.; Stoneley, Mark; Coldwell, Mark J.; Poncet, Didier; Shen, Ya-Ching; Morley, Simon J.; Bushell, Martin; Willis, Anne E.

2009-01-01

Initiation of protein synthesis in eukaryotes requires recruitment of the ribosome to the mRNA and its translocation to the start codon. There are at least two distinct mechanisms by which this process can be achieved; the ribosome can be recruited either to the cap structure at the 5′ end of the message or to an internal ribosome entry segment (IRES), a complex RNA structural element located in the 5′ untranslated region (5′-UTR) of the mRNA. However, it is not well understood how cellular IRESs function to recruit the ribosome or how the 40S ribosomal subunits translocate from the initial recruitment site on the mRNA to the AUG initiation codon. We have investigated the canonical factors that are required by the IRESs found in the 5′-UTRs of c-, L-, and N-myc, using specific inhibitors and a tissue culture-based assay system, and have shown that they differ considerably in their requirements. The L-myc IRES requires the eIF4F complex and the association of PABP and eIF3 with eIF4G for activity. The minimum requirements of the N- and c-myc IRESs are the C-terminal domain of eIF4G to which eIF4A is bound and eIF3, although interestingly this protein does not appear to be recruited to the IRES RNA via eIF4G. Finally, our data show that all three IRESs require a ternary complex, although in contrast to c- and L-myc IRESs, the N-myc IRES has a lesser requirement for a ternary complex. PMID:19124605

Down-regulation of 5S rRNA by miR-150 and miR-383 enhances c-Myc-rpL11 interaction and inhibits proliferation of esophageal squamous carcinoma cells.

PubMed

Wang, Xinyu; Ren, Yanli; Wang, Zhiqiong; Xiong, Xiangyu; Han, Sichong; Pan, Wenting; Chen, Hongwei; Zhou, Liqing; Zhou, Changchun; Yuan, Qipeng; Yang, Ming

2015-12-21

5S rRNA plays an important part in ribosome biology and is over-expression in multiple cancers. In this study, we found that 5S rRNA is a direct target of miR-150 and miR-383 in esophageal squamous cell carcinoma (ESCC). Overexpression of miR-150 and miR-383 inhibited ESCC cell proliferation in vitro and in vivo. Moreover, 5S rRNA silencing by miR-150 and miR-383 might intensify rpL11-c-Myc interaction, which attenuated role of c-Myc as an oncogenic transcriptional factor and dysregulation of multiple c-Myc target genes. Taken together, our results highlight the involvement of miRNAs in ribosomal regulation during tumorigenesis. Copyright © 2015 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.

Induction of the c-myc protooncogene following antigen binding to hapten-specific B cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Snow, E.C.; Fetherston, J.; Zimmer, S.

1986-03-01

Considerable controversy has centered on the role that the surface immunoglobulin (sIg) receptor for antigen plays during the induction of B cell activation. Stimulation by anti-Ig reagents has been shown to activate G/sub 0/ B cells to enter the cell cycle. The binding of thymus-dependent antigens to hapten-specific B cell populations apparently does not result in the movement of the antigen-binding cells (ABC) into the G/sub 1/ stage of the cell cycle. However, the authors have recently demonstrated that antigen binding to such hapten-specific B cells does result in the initiation of the membrane phosphatidylinositol cycle. In the present experiments,more » hapten-specific B cells (80-90% ABC, 99% in G/sub 0/) were incubated with either the correct hapten-carrier conjugate, with the carrier protein, or only media for 2 hours at 37/sup 0/C. At that time, total cellular RNA was isolated and subsequently analyzed by either dot blots or Northern gel techniques. The blots were probed with a (/sup 32/P)-c-myc SstI-Xhol fragment. The results indicate that hapten carrier stimulation of the hapten-specific B cells induces enhanced transcription of the c-myc gene. These observations lend further support to the premise that antigen binding to the sIg receptor results in the transduction to the cell of important signals and implicates the active participation of sIg during the process of antigen-mediated B cell activation.« less

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

Loss of MYC and E-box3 binding contributes to defective MYC-mediated transcriptional suppression of human MC-let-7a-1~let-7d in glioblastoma

PubMed Central

Wang, Zifeng; Lin, Sheng; Zhang, Ji; Xu, Zhenhua; Xiang, Yu; Yao, Hong; Ge, Lei; Xie, Dan; Kung, Hsiang-fu; Lu, Gang; Poon, Wai Sang; Liu, Quentin; Lin, Marie Chia-mi

2016-01-01

Previously, we reported that MYC oncoprotein down-regulates the transcription of human MC-let-7a-1~let-7d microRNA cluster in hepatocarcinoma (HCC). Surprisingly, in silico analysis indicated that let-7 miRNA expression levels are not reduced in glioblastoma (GBM). Here we investigated the molecular basis of this differential expression. Using human GBM U87 and U251 cells, we first demonstrated that forced over-expression of MYC indeed could not down-regulate the expression of human MC-let-7a-1~let-7d microRNA cluster in GBM. Furthermore, analysis of MC-let-7a-1~let-7d promoter in GBM indicated that MYC failed to inhibit the promoter activity. Pearson's correlation and Linear Regression analysis using the expression data from GSE55092 (HCC) and GSE4290 (GBM) demonstrated a converse relationship of MC-let-7a-1~let-7d and MYC only in HCC but not in GBM. To understand the underlying mechanisms, we examined whether MYC could bind to the non-canonical E-box 3 located in the promoter of MC-let-7a-1~let-7d. Results from both chromatin immune-precipitation (ChIP) and super-shift assays clearly demonstrated the loss of MYC and E-box 3 binding in GBM, suggesting for the first time that a defective MYC and E-box3 binding in GBM is responsible for the differential MYC mediated transcriptional inhibition of MC-let-7a-1~let-7d and potentially other tumor suppressors. MYC and let-7 are key oncoprotein and tumor suppressor, respectively. Understanding the molecular mechanisms of their regulations will provide new insight and have important implications in the therapeutics of GBM as well as other cancers. PMID:27409345

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. Copyright © 2011 Elsevier Inc. All rights reserved.

Expression, purification, and DNA-binding activity of the solubilized NtrC protein of Herbaspirillum seropedicae.

PubMed

Twerdochlib, Adriana L; Chubatsu, Leda S; Souza, Emanuel M; Pedrosa, Fábio O; Steffens, M Berenice R; Yates, M Geoffrey; Rigo, Liu U

2003-07-01

NtrC is a bacterial enhancer-binding protein (EBP) that activates transcription by the sigma54 RNA polymerase holoenzyme. NtrC has a three domain structure typical of EBP family. In Herbaspirillum seropedicae, an endophytic diazotroph, NtrC regulates several operons involved in nitrogen assimilation, including glnAntrBC. In order to over-express and purify the NtrC protein, DNA fragments containing the complete structural gene for the whole protein, and for the N-terminal+Central and Central+C-terminal domains were cloned into expression vectors. The NtrC and NtrC(N-terminal+Central) proteins were over-expressed as His-tag fusion proteins upon IPTG addition, solubilized using N-lauryl-sarcosyl and purified by metal affinity chromatography. The over-expressed His-tag-NtrC(Central+C-terminal) fusion protein was partially soluble and was also purified by affinity chromatography. DNA band-shift assays showed that the NtrC protein and the Central+C-terminal domains bound specifically to the H. seropedicae glnA promoter region. The C-terminal domain is presumably necessary for DNA-protein interaction and DNA-binding does not require a phosphorylated protein.

BRD4-targeted therapy induces Myc-independent cytotoxicity in Gnaq/11-mutatant uveal melanoma cells.

PubMed

Ambrosini, Grazia; Sawle, Ashley D; Musi, Elgilda; Schwartz, Gary K

2015-10-20

Uveal melanoma (UM) is an aggressive intraocular malignancy with limited therapeutic options. Both primary and metastatic UM are characterized by oncogenic mutations in the G-protein alpha subunit q and 11. Furthermore, nearly 40% of UM has amplification of the chromosomal arm 8q and monosomy of chromosome 3, with consequent anomalies of MYC copy number. Chromatin regulators have become attractive targets for cancer therapy. In particular, the bromodomain and extra-terminal (BET) inhibitor JQ1 has shown selective inhibition of c-Myc expression with antiproliferative activity in hematopoietic and solid tumors. Here we provide evidence that JQ1 had cytotoxic activity in UM cell lines carrying Gnaq/11 mutations, while in cells without the mutations had little effects. Using microarray analysis, we identified a large subset of genes modulated by JQ1 involved in the regulation of cell cycle, apoptosis and DNA repair. Further analysis of selected genes determined that the concomitant silencing of Bcl-xL and Rad51 represented the minimal requirement to mimic the apoptotic effects of JQ1 in the mutant cells, independently of c-Myc. In addition, administration of JQ1 to mouse xenograft models of Gnaq-mutant UM resulted in significant inhibition of tumor growth.Collectively, our results define BRD4 targeting as a novel therapeutic intervention against UM with Gnaq/Gna11 mutations.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Han, Yu; Zhong, Cuiping; Hong, Liu

2009-12-18

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

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.

PAF-Myc-Controlled Cell Stemness Is Required for Intestinal Regeneration and Tumorigenesis.

PubMed

Kim, Moon Jong; Xia, Bo; Suh, Han Na; Lee, Sung Ho; Jun, Sohee; Lien, Esther M; Zhang, Jie; Chen, Kaifu; Park, Jae-Il

2018-03-12

The underlying mechanisms of how self-renewing cells are controlled in regenerating tissues and cancer remain ambiguous. PCNA-associated factor (PAF) modulates DNA repair via PCNA. Also, PAF hyperactivates Wnt/β-catenin signaling independently of PCNA interaction. We found that PAF is expressed in intestinal stem and progenitor cells (ISCs and IPCs) and markedly upregulated during intestinal regeneration and tumorigenesis. Whereas PAF is dispensable for intestinal homeostasis, upon radiation injury, genetic ablation of PAF impairs intestinal regeneration along with the severe loss of ISCs and Myc expression. Mechanistically, PAF conditionally occupies and transactivates the c-Myc promoter, which induces the expansion of ISCs/IPCs during intestinal regeneration. In mouse models, PAF knockout inhibits Apc inactivation-driven intestinal tumorigenesis with reduced tumor cell stemness and suppressed Wnt/β-catenin signaling activity, supported by transcriptome profiling. Collectively, our results unveil that the PAF-Myc signaling axis is indispensable for intestinal regeneration and tumorigenesis by positively regulating self-renewing cells. Copyright © 2018 Elsevier Inc. All rights reserved.

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

Enhanced epithelial to mesenchymal transition (EMT) and upregulated MYC in ectopic lesions contribute independently to endometriosis.

PubMed

Proestling, Katharina; Birner, Peter; Gamperl, Susanne; Nirtl, Nadine; Marton, Erika; Yerlikaya, Gülen; Wenzl, Rene; Streubel, Berthold; Husslein, Heinrich

2015-07-22

Epithelial to mesenchymal transition (EMT) is a process in which epithelial cells lose polarity and cell-to-cell contacts and acquire the migratory and invasive abilities of mesenchymal cells. These abilities are thought to be prerequisites for the establishment of endometriotic lesions. A hallmark of EMT is the functional loss of E-cadherin (CDH1) expression in epithelial cells. TWIST1, a transcription factor that represses E-cadherin transcription, is among the EMT inducers. SNAIL, a zinc-finger transcription factor, and its close relative SLUG have similar properties to TWIST1 and are thus also EMT inducers. MYC, which is upregulated by estrogens in the uterus by an estrogen response cis-acting element (ERE) in its promoter, is associated with proliferation in endometriosis. The role of EMT and proliferation in the pathogenesis of endometriosis was evaluated by analyzing TWIST1, CDH1 and MYC expression. CDH1, TWIST1, SNAIL and SLUG mRNA expression was analyzed by qRT-PCR from 47 controls and 74 patients with endometriosis. Approximately 42 ectopic and 62 eutopic endometrial tissues, of which 30 were matched samples, were collected during the same surgical procedure. We evaluated TWIST1 and MYC protein expression by immunohistochemistry (IHC) in the epithelial and stromal tissue of 69 eutopic and 90 ectopic endometrium samples, of which 49 matched samples were analyzed from the same patient. Concordant expression of TWIST1/SNAIL/SLUG and CDH1 but also of TWIST1 and MYC was analyzed. We found that TWIST1, SNAIL and SLUG are overexpressed (p < 0.001, p = 0.016 and p < 0.001) in endometriosis, while CDH1 expression was concordantly reduced in these samples (p < 0.001). Similar to TWIST1, the epithelial expression of MYC was also significantly enhanced in ectopic endometrium compared to eutopic tissues (p = 0.008). We found exclusive expression of either TWIST1 or MYC in the same samples (p = 0.003). Epithelial TWIST1 is overexpressed in

The adaptive immune system promotes initiation of prostate carcinogenesis in a human c-Myc transgenic mouse model.

PubMed

Melis, Monique H M; Nevedomskaya, Ekaterina; van Burgsteden, Johan; Cioni, Bianca; van Zeeburg, Hester J T; Song, Ji-Ying; Zevenhoven, John; Hawinkels, Lukas J A C; de Visser, Karin E; Bergman, Andries M

2017-11-07

Increasing evidence from epidemiological and pathological studies suggests a role of the immune system in the initiation and progression of multiple cancers, including prostate cancer. Reports on the contribution of the adaptive immune system are contradictive, since both suppression and acceleration of disease development have been reported. This study addresses the functional role of lymphocytes in prostate cancer development using a genetically engineered mouse model (GEMM) of human c-Myc driven prostate cancer (Hi-Myc mice) combined with B and T cell deficiency (RAG1 -/- mice). From a pre-cancerous stage on, Hi-Myc mice showed higher accumulation of immune cells in their prostates then wild-type mice, of which macrophages were the most abundant. The onset of invasive adenocarcinoma was delayed in Hi-MycRAG1 -/- compared to Hi-Myc mice and associated with decreased infiltration of leukocytes into the prostate. In addition, lower levels of the cytokines CXCL2, CCL5 and TGF-β1 were detected in Hi-MycRAG1 -/- compared to Hi-Myc mouse prostates. These results from a GEMM of prostate cancer provide new insights into the promoting role of the adaptive immune system in prostate cancer development. Our findings indicate that the endogenous adaptive immune system does not protect against de novo prostate carcinogenesis in Hi-Myc transgenic mice, but rather accelerates the formation of invasive adenocarcinomas. This may have implications for the development of novel treatment strategies.

Calmodulin-mediated activation of Akt regulates survival of c-Myc-overexpressing mouse mammary carcinoma cells.

PubMed

Deb, Tushar B; Coticchia, Christine M; Dickson, Robert B

2004-09-10

c-Myc-overexpressing mammary epithelial cells are proapoptotic; their survival is strongly promoted by epidermal growth factor (EGF). We now demonstrate that EGF-induced Akt activation and survival in transgenic mouse mammary tumor virus-c-Myc mouse mammary carcinoma cells are both calcium/calmodulin-dependent. Akt activation is abolished by the phospholipase C-gamma inhibitor U-73122, by the intracellular calcium chelator BAPTA-AM, and by the specific calmodulin antagonist W-7. These results implicate calcium/calmodulin in the activation of Akt in these cells. In addition, Akt activation by serum and insulin is also inhibited by W-7. EGF-induced and calcium/calmodulin-mediated Akt activation occurs in both tumorigenic and non-tumorigenic mouse and human mammary epithelial cells, independent of their overexpression of c-Myc. These results imply that calcium/calmodulin may be a common regulator of Akt activation, irrespective of upstream receptor activator, mammalian species, and transformation status in mammary epithelial cells. However, only c-Myc-overexpressing mouse mammary carcinoma cells (but not normal mouse mammary epithelial cells) undergo apoptosis in the presence of the calmodulin antagonist W-7, indicating the vital selective role of calmodulin for survival of these cells. Calcium/calmodulin-regulated Akt activation is mediated directly by neither calmodulin kinases nor phosphatidylinositol 3-kinase (PI-3 kinase). Pharmacological inhibitors of calmodulin kinase kinase and calmodulin kinases II and III do not inhibit EGF-induced Akt activation, and calmodulin antagonist W-7 does not inhibit phosphotyrosine-associated PI-3 kinase activation. Akt is, however, co-immunoprecipitated with calmodulin in an EGF-dependent manner, which is inhibited by calmodulin antagonist W-7. We conclude that calmodulin may serve a vital regulatory function to direct the localization of Akt to the plasma membrane for its activation by PI-3 kinase.

Atypical rearrangement involving 3′-IGH@ and a breakpoint at least 400 Kb upstream of an intact MYC in a CLL patient with an apparently balanced t(8;14)(q24.1;q32) and negative MYC expression

PubMed Central

2013-01-01

The t(8;14)(q24.1;q32), the cytogenetic hallmark of Burkitt’s lymphoma, is also found, but rarely, in cases of chronic lymphocytic leukemia (CLL). Such translocation typically results in a MYC-IGH@ fusion subsequently deregulating and overexpressing MYC on der 14q32. In CLL, atypical rearrangements resulting in its gain or loss, within or outside of IGH@ or MYC locus, have been reported, but their clinical significance remains uncertain. Herein, we report a 67 year-old male with complex cytogenetic findings of apparently balanced t(8;14) and unreported complex rearrangements of IGH@ and MYC loci. His clinical, morphological and immunophenotypic features were consistent with the diagnosis of CLL. Interphase FISH studies revealed deletions of 11q22.3 and 13q14.3, and an extra copy of IGH@, indicative of rearrangement. Karyotype analysis showed an apparently balanced t(8;14)(q24.1;q32). Sequential GPG-metaphase FISH studies revealed abnormal signal patterns: rearrangement of IGH break apart probe with the 5’-IGH@ on derivative 8q24.1 and the 3’-IGH@ retained on der 14q; absence of MYC break apart-specific signal on der 8q; and, the presence of unsplit 5’-MYC-3’ break apart probe signals on der 14q. The breakpoint on 8q24.1 was found to be at least 400 Kb upstream of 5’ of MYC. In addition, FISH studies revealed two abnormal clones; one with 13q14.3 deletion, and the other, with concurrent 11q deletion and atypical rearrangements. Chromosome microarray analysis (CMA) detected a 7.1 Mb deletion on 11q22.3-q23.3 including ATM, a finding consistent with FISH results. While no significant copy number gain or loss observed on chromosomes 8, 12 and 13, a 455 Kb microdeletion of uncertain clinical significance was detected on 14q32.33. Immunohistochemistry showed co-expression of CD19, CD5, and CD23, positive ZAP-70 expression and absence of MYC expression. Overall findings reveal an apparently balanced t(8;14) and atypical complex rearrangements involving 3�