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Wang X, Lv Z, Xia H, Guo X, Wang J, Wang J, Liu M. Biochemical recurrence related metabolic novel signature associates with immunity and ADT treatment responses in prostate cancer. Cancer Med 2022; 12:862-878. [PMID: 35681277 PMCID: PMC9844602 DOI: 10.1002/cam4.4856] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2021] [Revised: 05/11/2022] [Accepted: 05/15/2022] [Indexed: 01/25/2023] Open
Abstract
BACKGROUND Prostate cancer (PCa) is a unique cancer from a metabolic perspective. Androgen receptor assumes a vital part in normal and malignant prostate cells regarding almost all aspects of cell metabolism, such as glucose, fat, amino acids, nucleotides, and so on. METHODS We used The Cancer Genome Atlas database as training set, Memorial Sloan-Kettering Cancer Center cohort as validation set, and Gene Expression Omnibus database (GSE70769) as test set to identify the optimal prognostic signature. We evaluated the signature in terms of biochemical progression-free survival (bPFS), ROC curve, clinicopathological features, independent prognostic indicators, tumor microenvironment, and infiltrating immune cells. Nomogram was built dependent on the results of cox regression analyses. GSEA algorithm was used to evaluate differences in metabolism. The signature's prediction of androgen deprivation therapy (ADT) response was validated based on two groups of basic cytological experiments treat with ADT (GSE143408 and GSE120343) and the transcriptional information of pre-ADT/post-ADT of six local PCa patients. RESULTS We finally input four screened genes into the stepwise regression model to construct metabolism-related signature. The signature shows good prediction performance in training set, verification set, and test set. A nomogram based on the PSA, Gleason score, T staging, and the signature risk score could predict 1-, 3-, and 5-year bPFS with the high area under curve values. Based on gene-set enrichment analysis, the characteristics of four genes signature could influence some important metabolic biological processes of PCa and were serendipitously found to be significantly related to androgen response. Subsequently, two cytological experimental data sets and our local patient sequencing data set verified that the signature may be helpful to evaluate the therapeutic response of PCa to ADT. CONCLUSIONS Our systematic study definite a metabolism-related gene signature to foresee prognosis of PCa patients which might add to individual prevention and treatment.
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Affiliation(s)
- Xuan Wang
- Department of UrologyBeijing Hospital, National Center of Gerontology, Institute of Geriatric Medicine, Chinese Academy of Medical SciencesBeijingPeople's Republic of China
- Graduate School of Peking Union Medical College and Chinese Academy of Medical SciencesBeijingPeople's Republic of China
| | - Zhengtong Lv
- Department of UrologyBeijing Hospital, National Center of Gerontology, Institute of Geriatric Medicine, Chinese Academy of Medical SciencesBeijingPeople's Republic of China
- Graduate School of Peking Union Medical College and Chinese Academy of Medical SciencesBeijingPeople's Republic of China
| | - Haoran Xia
- Department of UrologyBeijing Hospital, National Center of Gerontology, Institute of Geriatric Medicine, Chinese Academy of Medical SciencesBeijingPeople's Republic of China
- Graduate School of Peking Union Medical College and Chinese Academy of Medical SciencesBeijingPeople's Republic of China
| | - Xiaoxiao Guo
- Department of UrologyBeijing Hospital, National Center of Gerontology, Institute of Geriatric Medicine, Chinese Academy of Medical SciencesBeijingPeople's Republic of China
- Graduate School of Peking Union Medical College and Chinese Academy of Medical SciencesBeijingPeople's Republic of China
| | - Jianye Wang
- Department of UrologyBeijing Hospital, National Center of Gerontology, Institute of Geriatric Medicine, Chinese Academy of Medical SciencesBeijingPeople's Republic of China
- Graduate School of Peking Union Medical College and Chinese Academy of Medical SciencesBeijingPeople's Republic of China
| | - Jianlong Wang
- Department of UrologyBeijing Hospital, National Center of Gerontology, Institute of Geriatric Medicine, Chinese Academy of Medical SciencesBeijingPeople's Republic of China
- Graduate School of Peking Union Medical College and Chinese Academy of Medical SciencesBeijingPeople's Republic of China
| | - Ming Liu
- Department of UrologyBeijing Hospital, National Center of Gerontology, Institute of Geriatric Medicine, Chinese Academy of Medical SciencesBeijingPeople's Republic of China
- Graduate School of Peking Union Medical College and Chinese Academy of Medical SciencesBeijingPeople's Republic of China
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Yu S, Wang X, Zhu L, Xie P, Zhou Y, Jiang S, Chen H, Liao X, Pu S, Lei Z, Wang B, Ren Y. A systematic analysis of a potential metabolism-related prognostic signature for breast cancer patients. ANNALS OF TRANSLATIONAL MEDICINE 2021; 9:330. [PMID: 33708957 PMCID: PMC7944328 DOI: 10.21037/atm-20-7600] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Background Metabolic pathways play an essential role in breast cancer. However, the role of metabolism-related genes in the early diagnosis of breast cancer remains unknown. Methods In our study, RNA sequencing (RNA-seq) expression data and clinicopathological information from The Cancer Genome Atlas (TCGA) and GSE20685 were obtained. Univariate cox regression and least absolute shrinkage and selection operator (LASSO) regression analyses were performed on the differentially expressed metabolism-related genes. Then, the formula of the metabolism-related risk model was composed, and the risk score of each patient was calculated. The breast cancer patients were divided into high-risk and low-risk groups with a cutoff of the median expression value of the risk score, and the prognostic analysis was also used to analyze the survival time between these two groups. In the end, we also analyzed the expression, interaction, and correlation among genes in the metabolism-related gene risk model. Results The results from the prognostic analysis indicated that the survival was significantly poorer in the high-risk group than in the low-risk group in both TCGA and GSE20685 datasets. In addition, after adjusting for different clinicopathological features in multivariate analysis, the metabolism-related risk model remained an independent prognostic indicator in TCGA dataset. Conclusions In summary, we systematically developed a potential metabolism-related gene risk model for predicting prognosis in breast cancer patients.
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Affiliation(s)
- Shibo Yu
- Department of Breast Surgery, the First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, China
| | - Xiaowen Wang
- Department of Second Breast surgery, the Affiliated Tumor Hospital of Xinjiang Medical University, Urumqi, China
| | - Lizhe Zhu
- Department of Breast Surgery, the First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, China
| | - Peiling Xie
- Department of Breast Surgery, the First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, China
| | - Yudong Zhou
- Department of Breast Surgery, the First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, China
| | - Siyuan Jiang
- Department of Breast Surgery, the First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, China
| | - Heyan Chen
- Department of Breast Surgery, the First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, China
| | - Xiaoqin Liao
- Department of Breast Surgery, the First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, China
| | - Shengyu Pu
- Department of Breast Surgery, the First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, China
| | - Zhenzhen Lei
- Department of Breast Surgery, the First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, China
| | - Bin Wang
- Department of Breast Surgery, the First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, China
| | - Yu Ren
- Department of Breast Surgery, the First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, China
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Wu T, Zhang D, Lin M, Yu L, Dai T, Li S, Yu F, Lu L, Zheng L, Zhong S. Exploring the Role and Mechanism of pAMPK α-Mediated Dysregulation of Brf1 and RNA Pol III Genes. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2021; 2021:5554932. [PMID: 33995823 PMCID: PMC8081602 DOI: 10.1155/2021/5554932] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/21/2021] [Revised: 03/30/2021] [Accepted: 04/05/2021] [Indexed: 02/05/2023]
Abstract
TF IIB-related factor 1 (Brf1) is a key transcription factor of RNA polymerase III (Pol III) genes. Our early studies have demonstrated that Brf1 and Pol III genes are epigenetically modulated by histone H3 phosphorylation. Here, we have further investigated the relationship of the abnormal expression of Brf1 with a high level of phosphorylated AMPKα (pAMPKα) and explored the role and molecular mechanism of pAMPKα-mediated dysregulation of Brf1 and Pol III genes in lung cancer. Brf1 is significantly overexpressed in lung cancer cases. The cases with high Brf1 expression display short overall survival times. Elevation of Brf1 expression is accompanied by a high level of pAMPKα. Brf1 and pAMPKα colocalize in nuclei. Further analysis indicates that the carcinogen MNNG induces pAMPKα to upregulate Brf1 expression, resulting in the enhancement of Pol III transcription. In contrast, inhibiting pAMPKα decreases cellular levels of Brf1, resulting in the reduction of Pol III gene transcription to attenuate the rates of cell proliferation and colony formation of lung cancer cells. These outcomes demonstrate that high Brf1 expression reveals a worse prognosis in lung cancer patients. pAMPKα-mediated dysregulation of Brf1 and Pol III genes plays important roles in cell proliferation, colony formation, and tumor development of lung cancer. Brf1 may be a biomarker for establishing the prognosis of lung cancer. It is a new mechanism that pAMPKα mediates dysregulation of Brf1 and Pol III genes to promote lung cancer development.
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Affiliation(s)
- Teng Wu
- GMU-GIBH Joint School of Life Sciences, Guangzhou Medical University, Guangzhou, China
| | - Dongkun Zhang
- Department of Thoracic Surgery, Guangdong Provincial People's Hospital, Guangdong Academy of Medical Sciences, Guangzhou, China
| | - Mingen Lin
- The First Affiliated Hospital of Shantou University Medical College, China
- Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Lihong Yu
- GMU-GIBH Joint School of Life Sciences, Guangzhou Medical University, Guangzhou, China
| | - Ting Dai
- GMU-GIBH Joint School of Life Sciences, Guangzhou Medical University, Guangzhou, China
| | - Shuai Li
- GMU-GIBH Joint School of Life Sciences, Guangzhou Medical University, Guangzhou, China
| | - Fenghai Yu
- GMU-GIBH Joint School of Life Sciences, Guangzhou Medical University, Guangzhou, China
| | - Lei Lu
- GMU-GIBH Joint School of Life Sciences, Guangzhou Medical University, Guangzhou, China
- Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Liling Zheng
- First Hospital of Quanzhou Affiliated to Fujian Medical University, China
| | - Shuping Zhong
- Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
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Hong Z, Fang Z, Lei J, Shi G, Zhang Y, He Z, Li B W, Zhong S. The significance of Runx2 mediating alcohol-induced Brf1 expression and RNA Pol III gene transcription. Chem Biol Interact 2020; 323:109057. [PMID: 32198086 PMCID: PMC7261693 DOI: 10.1016/j.cbi.2020.109057] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2019] [Accepted: 03/10/2020] [Indexed: 02/05/2023]
Abstract
Runx2 (Runt-related transcription factor 2) is a key transcription factor which is associated with osteoblast differentiation and expressed in ER+ (estrogen receptor positive) human breast cancer cell lines. Runx2 also participates in mammary gland development. Deregulation of RNA Pol III genes (polymerase III-dependent genes) is tightly linked to tumor development, while Brf1 (TFIIB-related factor 1) specifically regulates these gene transcription. However, nothing is known about the effect of Runx2 on Brf1 expression and Pol III gene transcription. Expression of Runx2, Brf1 and Pol III genes from the samples of human breast cancer and cell culture model were determined by the assays of RT-qPCR, immunoblot, luciferase reporter activity, immunohistochemistry, chromatin immunoprecipitation and Immunofluorescence. High expression of Runx2 is observed in the cases of breast cancer. The patients of high Runx2 expression at early stages display longer survival period, whereas the cases of high Runx2 at advanced stages reveal faster recurrence. The identification of signaling pathway indicates that JNK1 and c-Jun mediate Runx2 transcription. Repression of Runx2 reduces Brf1 expression and Pol III gene transcription. Further analysis indicates that Runx2 is colocalized with Brf1 in nucleus of breast cancer tissue. Both Runx2 and Brf1 synergistically modulate Pol III gene transcription. These studies indicate that Brf1 overexpression is able to be used as an early diagnosis biomarker of breast cancer, while high Runx2 expression indicates long survival period and faster recurrence. Runx2 mediates the deregulation of Brf1 and Pol III genes and its abnormal expression predicts the worse prognosis of breast cancer.
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Affiliation(s)
- Zaifa Hong
- Affiliated Cancer Hospital & Institute of Guangzhou Medical University, China; Department of Medicine, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Zeng Fang
- Laboratory of General Surgery and Department of Breast and Thyroid Surgery, First Affiliated Hospital, Sun Yat-sen University, Guangzhou, China
| | - Junxia Lei
- School of Medicine, South China University of Technology, China; Department of Medicine, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Ganggang Shi
- Department of Pharmacology, Shantou University Medical College, China
| | - Yanmei Zhang
- Department of Pharmacology, Shantou University Medical College, China; Department of Medicine, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Zhiming He
- Affiliated Cancer Hospital & Institute of Guangzhou Medical University, China
| | - Wen Li B
- Laboratory of General Surgery and Department of Breast and Thyroid Surgery, First Affiliated Hospital, Sun Yat-sen University, Guangzhou, China.
| | - Shuping Zhong
- Department of Medicine, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA.
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Petrie JL, Swan C, Ingram RM, Frame FM, Collins AT, Dumay-Odelot H, Teichmann M, Maitland NJ, White RJ. Effects on prostate cancer cells of targeting RNA polymerase III. Nucleic Acids Res 2019; 47:3937-3956. [PMID: 30820548 PMCID: PMC6486637 DOI: 10.1093/nar/gkz128] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2019] [Revised: 02/13/2019] [Accepted: 02/19/2019] [Indexed: 12/12/2022] Open
Abstract
RNA polymerase (pol) III occurs in two forms, containing either the POLR3G subunit or the related paralogue POLR3GL. Whereas POLR3GL is ubiquitous, POLR3G is enriched in undifferentiated cells. Depletion of POLR3G selectively triggers proliferative arrest and differentiation of prostate cancer cells, responses not elicited when POLR3GL is depleted. A small molecule pol III inhibitor can cause POLR3G depletion, induce similar differentiation and suppress proliferation and viability of cancer cells. This response involves control of the fate-determining factor NANOG by small RNAs derived from Alu short interspersed nuclear elements. Tumour initiating activity in vivo can be reduced by transient exposure to the pol III inhibitor. Untransformed prostate cells appear less sensitive than cancer cells to pol III depletion or inhibition, raising the possibility of a therapeutic window.
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Affiliation(s)
- John L Petrie
- Department of Biology, University of York, Heslington, York YO10 5DD, UK
| | - Caroline Swan
- Department of Biology, University of York, Heslington, York YO10 5DD, UK
| | - Richard M Ingram
- Department of Biology, University of York, Heslington, York YO10 5DD, UK
| | - Fiona M Frame
- Department of Biology, University of York, Heslington, York YO10 5DD, UK
| | - Anne T Collins
- Department of Biology, University of York, Heslington, York YO10 5DD, UK
| | - Hélène Dumay-Odelot
- Université de Bordeaux, ARNA Laboratory, F-33076 Bordeaux, France INSERM, U1212 - CNRS UMR 5320, ARNA Laboratory, F-33000 Bordeaux, France
| | - Martin Teichmann
- Université de Bordeaux, ARNA Laboratory, F-33076 Bordeaux, France INSERM, U1212 - CNRS UMR 5320, ARNA Laboratory, F-33000 Bordeaux, France
| | - Norman J Maitland
- Department of Biology, University of York, Heslington, York YO10 5DD, UK
| | - Robert J White
- Department of Biology, University of York, Heslington, York YO10 5DD, UK
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6
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Liang X, Xie R, Su J, Ye B, Wei S, Liang Z, Bai R, Chen Z, Li Z, Gao X. Inhibition of RNA polymerase III transcription by Triptolide attenuates colorectal tumorigenesis. JOURNAL OF EXPERIMENTAL & CLINICAL CANCER RESEARCH : CR 2019; 38:217. [PMID: 31122284 PMCID: PMC6533717 DOI: 10.1186/s13046-019-1232-x] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/01/2019] [Accepted: 05/15/2019] [Indexed: 12/31/2022]
Abstract
Background Upregulation of RNA polymerase (Pol) III products, including tRNAs and 5S rRNA, in tumor cells leads to enhanced protein synthesis and tumor formation, making it a potential target for cancer treatment. In this study, we evaluated the inhibition of Pol III transcription by triptolide and the anti-cancer effect of this drug in colorectal tumorigenesis. Methods The effect of triptolide on colorectal cancer development was assessed in colorectal cancer mouse models, 3D organoids, and cultured cells. Colorectal cancer cells were treated with triptolide. Pol III transcription was measured by real-time quantitative polymerase chain reaction (PCR). The formation of TFIIIB, a multi-subunit transcription factor for Pol III, was determined by chromatin immunoprecipitation (ChIP), co-immunoprecipitation (Co-IP), and fluorescence resonance energy transfer (FRET). Results Triptolide reduced both tumor number and tumor size in adenomatous polyposis coli (Apc) mutated (ApcMin/+) mice as well as AOM/DSS-induced mice. Moreover, triptolide effectively inhibited colorectal cancer cell proliferation, colony formation, and organoid growth in vitro, which was associated with decreased Pol III target genes. Mechanistically, triptolide treatment blocked TBP/Brf1interaction, leading to the reduced formation of TFIIIB at the promoters of tRNAs and 5S rRNA. Conclusions Together, our data suggest that inhibition of Pol III transcription with existing drugs such as triptolide provides a new avenue for developing novel therapies for colorectal cancer. Electronic supplementary material The online version of this article (10.1186/s13046-019-1232-x) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Xia Liang
- Medical Research Institute, & Guangdong Women and Children's Disease Precision Diagnosis and Treatment Engineering Technology Research Center, Baoan Maternal and Child Health Hospital, Jinan University, Shenzhen, 518102, China
| | - Renxiang Xie
- Department of Public Health, Zhejiang University School of Medicine, Hangzhou, 310058, China
| | - Jinfeng Su
- Medical Research Institute, & Guangdong Women and Children's Disease Precision Diagnosis and Treatment Engineering Technology Research Center, Baoan Maternal and Child Health Hospital, Jinan University, Shenzhen, 518102, China
| | - Bingqi Ye
- Department of Public Health, Zhejiang University School of Medicine, Hangzhou, 310058, China
| | - Saisai Wei
- Sir Run-Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, 310058, China
| | - Zhibing Liang
- Medical Research Institute, & Guangdong Women and Children's Disease Precision Diagnosis and Treatment Engineering Technology Research Center, Baoan Maternal and Child Health Hospital, Jinan University, Shenzhen, 518102, China
| | - Rongpan Bai
- Department of Public Health, Zhejiang University School of Medicine, Hangzhou, 310058, China
| | - Zhanghui Chen
- Affiliated Central People's Hospital of Zhanjiang, Guangdong Medical University, Zhanjiang, 524045, China
| | - Zhongxiang Li
- Medical Research Institute, & Guangdong Women and Children's Disease Precision Diagnosis and Treatment Engineering Technology Research Center, Baoan Maternal and Child Health Hospital, Jinan University, Shenzhen, 518102, China.
| | - Xiangwei Gao
- Department of Public Health, Zhejiang University School of Medicine, Hangzhou, 310058, China.
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Lee HH, Wang YN, Hung MC. Functional roles of the human ribonuclease A superfamily in RNA metabolism and membrane receptor biology. Mol Aspects Med 2019; 70:106-116. [PMID: 30902663 DOI: 10.1016/j.mam.2019.03.003] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2019] [Accepted: 03/17/2019] [Indexed: 02/08/2023]
Abstract
The human ribonuclease A (hRNase A) superfamily is comprised of 13 members of secretory RNases, most of which are recognized as catabolic enzymes for their ribonucleolytic activity to degrade ribonucleic acids (RNAs) in the extracellular space, where they play a role in innate host defense and physiological homeostasis. Interestingly, human RNases 9-13, which belong to a non-canonical subgroup of the hRNase A superfamily, are ribonucleolytic activity-deficient proteins with unclear biological functions. Moreover, accumulating evidence indicates that secretory RNases, such as human RNase 5, can be internalized into cells facilitated by membrane receptors like the epidermal growth factor receptor to regulate intracellular RNA species, in particular non-coding RNAs, and signaling pathways by either a ribonucleolytic activity-dependent or -independent manner. In this review, we summarize the classical role of hRNase A superfamily in the metabolism of extracellular and intracellular RNAs and update its non-classical function as a cognate ligand of membrane receptors. We further discuss the biological significance and translational potential of using secretory RNases as predictive biomarkers or therapeutic agents in certain human diseases and the pathological settings for future investigations.
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Affiliation(s)
- Heng-Huan Lee
- Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, Unit 108, 1515 Holcombe Boulevard, Houston, TX, 77030, USA
| | - Ying-Nai Wang
- Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, Unit 108, 1515 Holcombe Boulevard, Houston, TX, 77030, USA
| | - Mien-Chie Hung
- Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, Unit 108, 1515 Holcombe Boulevard, Houston, TX, 77030, USA; Graduate Institute of Biomedical Sciences and Center for Molecular Medicine, China Medical University, Taichung, 404, Taiwan; Department of Biotechnology, Asia University, Taichung 413, Taiwan.
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8
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Chen CY, Lanz RB, Walkey CJ, Chang WH, Lu W, Johnson DL. Maf1 and Repression of RNA Polymerase III-Mediated Transcription Drive Adipocyte Differentiation. Cell Rep 2018; 24:1852-1864. [PMID: 30110641 PMCID: PMC6138453 DOI: 10.1016/j.celrep.2018.07.046] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2017] [Revised: 04/05/2018] [Accepted: 07/12/2018] [Indexed: 12/11/2022] Open
Abstract
RNA polymerase (pol) III transcribes a variety of small untranslated RNAs involved in transcription, RNA processing, and translation. RNA pol III and its components are altered in various human developmental disorders, yet their roles in cell fate determination and development are poorly understood. Here we demonstrate that Maf1, a transcriptional repressor, promotes induction of mouse embryonic stem cells (mESCs) into mesoderm. Reduced Maf1 expression in mESCs and preadipocytes impairs adipogenesis, while ectopic Maf1 expression in Maf1-deficient cells enhances differentiation. RNA pol III repression by chemical inhibition or knockdown of Brf1 promotes adipogenesis. Altered RNA pol III-dependent transcription produces select changes in mRNAs with a significant enrichment of adipogenic gene signatures. Furthermore, RNA pol III-mediated transcription positively regulates long non-coding RNA H19 and Wnt6 expression, established adipogenesis inhibitors. Together, these studies reveal an important and unexpected function for RNA pol III-mediated transcription and Maf1 in mesoderm induction and adipocyte differentiation.
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Affiliation(s)
- Chun-Yuan Chen
- Department of Biochemistry and Molecular Biology, University of Southern California, Los Angeles, CA, USA; Department of Molecular and Cellular Biology and the Dan L. Duncan Cancer Center, Baylor College of Medicine, Houston, TX, USA
| | - Rainer B Lanz
- Department of Molecular and Cellular Biology and the Dan L. Duncan Cancer Center, Baylor College of Medicine, Houston, TX, USA
| | - Christopher J Walkey
- Department of Molecular and Cellular Biology and the Dan L. Duncan Cancer Center, Baylor College of Medicine, Houston, TX, USA
| | - Wen-Hsuan Chang
- Eli and Edythe Broad Center for Regenerative Medicine and Stem Cell Research, University of Southern California, Los Angeles, CA, USA
| | - Wange Lu
- Department of Biochemistry and Molecular Biology, University of Southern California, Los Angeles, CA, USA; Eli and Edythe Broad Center for Regenerative Medicine and Stem Cell Research, University of Southern California, Los Angeles, CA, USA
| | - Deborah L Johnson
- Department of Molecular and Cellular Biology and the Dan L. Duncan Cancer Center, Baylor College of Medicine, Houston, TX, USA.
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9
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Epithelialization of mouse ovarian tumor cells originating in the fallopian tube stroma. Oncotarget 2018; 7:66077-66086. [PMID: 27602775 PMCID: PMC5323216 DOI: 10.18632/oncotarget.11808] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2016] [Accepted: 08/13/2016] [Indexed: 12/13/2022] Open
Abstract
Epithelial ovarian carcinoma accounts for 90% of all ovarian cancer and is the most deadly gynecologic malignancy. Recent studies have suggested that fallopian tube fimbriae can be the origin of cells for high-grade serous subtype of epithelial ovarian carcinoma (HGSOC). A mouse HGSOC model with conditional Dicer-Pten double knockout (Dicer-Pten DKO) developed primary tumors, intriguingly, from the fallopian tube stroma. We examined the growth and epithelial phenotypes of the Dicer-Pten DKO mouse tumor cells contributable by each gene knockout. Unlike human ovarian epithelial cancer cells that expressed full-length E-cadherin, the Dicer-Pten DKO stromal tumor cells expressed cleaved E-cadherin fragments and metalloproteinase 2, a mixture of epithelial and mesenchymal markers. Although the Dicer-Pten DKO tumor cells lost the expression of mature microRNAs as expected, they showed high levels of tRNA fragment expression and enhanced AKT activation due to the loss of PTEN function. Introduction of a Dicer1-expressing construct into the DKO mouse tumor cells significantly reduced DNA synthesis and the cell growth rate, with concurrent diminished adhesion and ZO1 epithelial staining. Hence, it is likely that the loss of Dicer promoted mesenchymal-epithelial transition in fallopian tube stromal cells, and in conjunction with Pten loss, further promoted cell proliferation and epithelial-like tumorigenesis.
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10
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WITHDRAWN: Abnormal expression of TFIIIB subunits and RNA Pol III genes is associated with hepatocellular carcinoma. LIVER RESEARCH 2017. [DOI: 10.1016/j.livres.2017.08.006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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11
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Wen H, Li P, Ma H, Zheng J, Yu Y, Lv G. High expression of Sam68 in sacral chordomas is associated with worse clinical outcomes. Onco Targets Ther 2017; 10:4691-4700. [PMID: 29026317 PMCID: PMC5626414 DOI: 10.2147/ott.s147446] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Src-associated in mitosis of 68 kDa (Sam68), also known as KHDRBS1 (KH domain-containing, RNA-binding, signal transduction-associated 1), is a member of the signal transduction and activation of RNA family. Previous studies have demonstrated that the aberrant expression of Sam68 is associated with the progression and prognosis of a variety of cancers, but little is known about its expression and role in chordomas, which are rare and aggressive bone neoplasms. In this study, we analyzed 40 tumor tissues and 20 distant normal tissues obtained from 40 patients with sacral chordoma using immunohistochemistry, and observed the expression of Sam68 was significantly upregulated in sacral chordomas compared with normal tissues (P=0.001). A positive correlation between the expression of Sam68 and the cell proliferation index Ki-67 was determined using Spearman’s rank correlation test (γ =0.599, P<0.001). In addition, high expression of Sam68 was significantly associated with surrounding muscle invasion (P<0.001). Moreover, Kaplan–Meier curves showed that patients with overexpressed Sam68 had shorter local recurrence-free survival time (P<0.001). Lastly, multivariate analysis indicated that Sam68 is an independent prognostic factor for the local recurrence-free survival of sacral chordomas (hazard ratio =5.929, 95% CI: 1.092–32.188, P=0.039). Our findings suggest the use of Sam68 as a predictor for the recurrence of sacral chordomas.
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Affiliation(s)
- Hai Wen
- Department of Spine Surgery, The Second Xiangya Hospital of Central South University, Changsha, Hunan, China
| | - Pengzhi Li
- Department of Spine Surgery, The Second Xiangya Hospital of Central South University, Changsha, Hunan, China
| | - Hong Ma
- Department of Spine Surgery, The Second Xiangya Hospital of Central South University, Changsha, Hunan, China
| | - Jiaoyun Zheng
- Department of Pathology, The Second Xiangya Hospital of Central South University, Changsha, Hunan, China
| | - Yipin Yu
- Department of Spine Surgery, The Second Xiangya Hospital of Central South University, Changsha, Hunan, China
| | - Guohua Lv
- Department of Spine Surgery, The Second Xiangya Hospital of Central South University, Changsha, Hunan, China
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12
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Lei J, Chen S, Zhong S. Abnormal expression of TFIIIB subunits and RNA Pol III genes is associated with hepatocellular carcinoma. LIVER RESEARCH 2017; 1:112-120. [PMID: 29276645 PMCID: PMC5739085 DOI: 10.1016/j.livres.2017.08.005] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The levels of the products of RNA polymerase III-dependent genes (Pol III genes), including tRNAs and 5S rRNA, are elevated in transformed and tumor cells, which potentiate tumorigenesis. TFIIB-related factor 1 (Brf1) is a key transcription factor and specifically regulates the transcription of Pol III genes. In vivo and in vitro studies have demonstrated that a decrease in Brf1 reduces Pol III gene transcription and is sufficient for inhibiting cell transformation and tumor formation. Emerging evidence indicates that dysregulation of Brf1 and Pol III genes is linked to the development of hepatocellular carcinoma (HCC) in humans and animals. We have reported that Brf1 is overexpressed in human liver cancer patients and that those with high Brf1 levels have shorter survivals. This review summarizes the effects of dysregulation of these genes on HCC and their regulation by signaling pathways and epigenetics. These novel data should help us determine the molecular mechanisms of HCC from a different perspective and guide the development of therapeutic approaches for HCC patients.
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Affiliation(s)
- Junxia Lei
- School of medicine, South china university of technology, China
- Department of Biochemistry and Molecular Biology, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Songlin Chen
- Department of Cardiothoracic Surgery, Xiamen University Affiliated Southeast Hospital, China
- Department of Biochemistry and Molecular Biology, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Shuping Zhong
- Department of Biochemistry and Molecular Biology, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
- Corresponding author. Department of Biochemistry and Molecular Biology, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA. (S. Zhong)
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13
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Yi Y, Huang C, Zhang Y, Tian S, Lei J, Chen S, Shi G, Wu Z, Xia N, Zhong S. Exploring a common mechanism of alcohol-induced deregulation of RNA Pol III genes in liver and breast cells. Gene 2017; 626:309-318. [PMID: 28552569 PMCID: PMC5521807 DOI: 10.1016/j.gene.2017.05.048] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2017] [Revised: 05/10/2017] [Accepted: 05/24/2017] [Indexed: 02/07/2023]
Abstract
Alcohol intake is associated with numbers of different human cancers, such as hepatocellular carcinoma (HCC) and breast cancer. However, the molecular mechanism remains to be elucidated. RNA polymerase III-dependent genes (Pol III genes) deregulation elevates cellular production of tRNAs and 5S rRNA, resulting in an increase in translational capacity, which promote cell transformation and tumor formation. To explore a common mechanism of alcohol-associated human cancers, we have comparably analyzed that alcohol causes deregulation of Pol III genes in liver and breast cells. Our results reveal that alcohol enhances RNA Pol III gene transcription in both liver and breast cells. The induction of Pol III genes caused by alcohol in ER+ breast cancer lines or liver tumor lines are significantly higher than in their non-tumor cell lines. Alcohol increases cellular levels of Brf1 mRNA and protein, (which depeted) Brf1 is a key transcription factor and specifically regulate Pol III gene activity. Alcohol activates JNK1 to upregulate transcription of Brf1 and Pol III genes, whereas inhibition of JNK1 by SP600125 or its siRNA significantly decreases the induction of these genes. Furthermore, alcohol increases the rates of transformation of liver and breast cells, repressed JNK1 and Brf1 expression decrease transcription of Pol III genes and reduce the rates of colony formation of AML-12 and MCF-10 cells. Together, these studies support the idea that alcohol induces deregulation of Brf1 and RNA Pol III genes in liver and breast cells, which share a common signaling pathway to promote cell transformation. Through the common mechanism, alcohol-induced deregulation of RNA Pol III genes brings about greater phenotypic changes.
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Affiliation(s)
- Yunfeng Yi
- Department of Cardiothoracic Surgery, Xiamen University Affiliated Southeast Hospital, China
| | - Chenghao Huang
- State Key Laboratory of Molecular Vaccinology and Molecular Diagnostics, National Institute of Diagnostics and Vaccine Development in Infectious Diseases, School of Public Health, Xiamen University, China
| | - Yanmei Zhang
- Department of Pharmacology, Shantou University Medical College, China
| | - Suke Tian
- Department of Cardiothoracic Surgery, Xiamen University Affiliated Southeast Hospital, China
| | - Junxia Lei
- Department of Parasitology, Zhongshan School of Medicine, Sun Yat-Sen University, China
| | - Songlin Chen
- Department of Cardiothoracic Surgery, Xiamen University Affiliated Southeast Hospital, China
| | - Ganggang Shi
- Department of Pharmacology, Shantou University Medical College, China
| | - Zhongdao Wu
- Department of Parasitology, Zhongshan School of Medicine, Sun Yat-Sen University, China
| | - Ningshao Xia
- State Key Laboratory of Molecular Vaccinology and Molecular Diagnostics, National Institute of Diagnostics and Vaccine Development in Infectious Diseases, School of Public Health, Xiamen University, China
| | - Shuping Zhong
- Department of Pharmacology, Shantou University Medical College, China; Cancer Center of Guangzhou Medical University, China; Department of Biochemistry and Molecular Biology, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA.
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Zamani-Ahmadmahmudi M, Dabiri S, Nadimi N. Identification of pathway-based prognostic gene signatures in patients with multiple myeloma. Transl Res 2017; 185:47-57. [PMID: 28549851 DOI: 10.1016/j.trsl.2017.05.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/25/2017] [Revised: 04/25/2017] [Accepted: 05/01/2017] [Indexed: 12/17/2022]
Abstract
Molecular profiling is used to extract prognostic gene signatures in different cancers such as multiple myeloma (MM), which is the second most common hematological malignancy. In this study, we utilized gene expression profiles to find biological pathways that could efficiently predict survival time in patients with MM. Four data sets-namely GSE2658 (559 samples), GSE9782 (264 samples), GSE6477 (147 samples), and GSE57317 (55 samples)-were employed. GSE2658 was used as a training data set and the others as validation data sets. The genes significantly associated with survival were identified using the univariate Cox proportional hazards analysis, and their roles in the biological pathways were explored using the Gene-Set Enrichment Analysis (GSEA) in the training data set. Next, the significant genes and their corresponding pathways were used to reconstruct pathway-based prognostic signatures. Thereafter, the significant gene signatures were externally validated in 3 independent cohorts-namely GSE9782, GSE6477, and GSE57317. Our results revealed that 9 pathway-based prognostic signatures were able to efficiently predict survival time in the training data set (Ps < 0.01). The testing of these signatures in the validation data sets demonstrated that 3 signatures-namely MYC targets, spliceosome, and metabolism of RNA-were able to strongly predict the clinical outcome in the 3 cohorts at P values < 0.01. In addition, in the multivariate Cox analysis, the 3 gene signatures remained as independent prognostic factors compared with the routine prognostic variables in MM-namely serum albumin, serum β2-microglobulin, and age. These signatures were by far the most powerful independent prognostic factors (MYC targets: P = 0.009, spliceosome: P = 0.024, and metabolism of RNA: P < 0.001).
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Affiliation(s)
- Mohamad Zamani-Ahmadmahmudi
- Department of Clinical Science, Faculty of Veterinary Medicine, Shahid Bahonar University of Kerman, Kerman, Iran.
| | - Shahreyar Dabiri
- Department of Pathology, Faculty of Medicine, Kerman University of Medical Science, Kerman, Iran
| | - Nadia Nadimi
- Department of Clinical Science, Faculty of Veterinary Medicine, Shahid Bahonar University of Kerman, Kerman, Iran
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15
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Johnson DL, Stiles BL. Maf1, A New PTEN Target Linking RNA and Lipid Metabolism. Trends Endocrinol Metab 2016; 27:742-750. [PMID: 27296319 PMCID: PMC5035567 DOI: 10.1016/j.tem.2016.04.016] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/29/2016] [Revised: 04/22/2016] [Accepted: 04/29/2016] [Indexed: 01/07/2023]
Abstract
PTEN is a critical tumor suppressor whose dysregulation leads to metabolic disease and cancer. How these diseases are linked at a molecular level is poorly understood. Maf1 is a novel PTEN target that connects PTEN's ability to repress intracellular lipid accumulation with its tumor suppressor function. Maf1 represses the expression of rRNAs and tRNAs to restrain biosynthetic capacity and oncogenic transformation. Recent studies demonstrate that Maf1 also controls intracellular lipid accumulation. In animal models, dysregulation of RNA polymerase I- and III-dependent transcription, and subsequent upregulation of rRNAs and tRNAs, leads to altered lipid metabolism and storage. Together these results identify unexpected connections between RNA and lipid metabolism that may help explain the strong epidemiological association between obesity and cancer.
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16
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Wang Y, Zhang W, Wang X, Wang D, Xie J, Tang C, Xi Q, Zhong J, Deng Y. Expression of Sam68 Correlates With Cell Proliferation and Survival in Epithelial Ovarian Cancer. Reprod Sci 2016; 24:97-108. [PMID: 27222230 DOI: 10.1177/1933719116650757] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Src associated in mitosis, 68 kDa (Sam68) is a KH domain RNA-binding protein that belongs to the signal transduction and activation of RNA family. It is a multifunctional protein known to regulate cellular signal transduction, transcription, RNA metabolism, proliferation, and apoptosis, thus implicated in tumor growth. Herein, we investigated the clinical significance of Sam68 in human epithelial ovarian cancer (EOC). Western blot and immunohistochemical staining demonstrated that Sam68 expression was upregulated in EOC tissues and cell lines. Statistical analysis showed that high expression of Sam68 correlated with poor prognosis of patients with EOC. In vitro, serum starvation-refeeding experiment was primarily performed to confirm that Sam68 participated in the cell cycle progression of EOC cell lines. Then knocking down Sam68 level with small interfering RNA, cell cycle was arrested at G1 phase and cell proliferation impaired. Furthermore, we demonstrated that the antiproliferative effect of silencing Sam68 in EOC cells was associated with the upregulation of cyclin-dependent kinase inhibitors p21Cip1 and p27Kip1, along with the downregulation of p-FOXO3a, p-Akt, and p-GSK-3β. Taken together, our findings uncovered that Sam68 played an important role in promoting the proliferation of human ovarian cancer, thereby might be a novel therapeutic target for EOC.
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Affiliation(s)
- Yingying Wang
- 1 Jiangsu Province Key Laboratory for Inflammation and Molecular Drug Target, Department of Pathogen Biology, Medical College, Nantong University, Nantong, People's Republic of China
| | - Weiwei Zhang
- 2 Department of Obstetrics and Gynecology, Affiliated Hospital of Nantong University, Nantong, People's Republic of China
| | - Xia Wang
- 3 Center for Reproductive Medicine, Affiliated Hospital of Nantong University, Nantong, People's Republic of China
| | - Di Wang
- 3 Center for Reproductive Medicine, Affiliated Hospital of Nantong University, Nantong, People's Republic of China
| | - Juan Xie
- 3 Center for Reproductive Medicine, Affiliated Hospital of Nantong University, Nantong, People's Republic of China
| | - Chunhui Tang
- 2 Department of Obstetrics and Gynecology, Affiliated Hospital of Nantong University, Nantong, People's Republic of China
| | - Qinghua Xi
- 2 Department of Obstetrics and Gynecology, Affiliated Hospital of Nantong University, Nantong, People's Republic of China
| | - Jianxin Zhong
- 2 Department of Obstetrics and Gynecology, Affiliated Hospital of Nantong University, Nantong, People's Republic of China
| | - Yan Deng
- 2 Department of Obstetrics and Gynecology, Affiliated Hospital of Nantong University, Nantong, People's Republic of China
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17
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Li Y, Tsang CK, Wang S, Li X, Yang Y, Fu L, Huang W, Li M, Wang H, Zheng XS. MAF1 suppresses AKT-mTOR signaling and liver cancer through activation of PTEN transcription. Hepatology 2016; 63:1928-42. [PMID: 26910647 PMCID: PMC5021206 DOI: 10.1002/hep.28507] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/26/2015] [Accepted: 02/17/2016] [Indexed: 12/12/2022]
Abstract
UNLABELLED The phosphatidylinositol 3-kinase/phosphatidylinositol 3,4,5-trisphosphate 3-phosphatase/protein kinase B/mammalian target of rapamycin (PI3K-PTEN-AKT-mTOR) pathway is a central controller of cell growth and a key driver for human cancer. MAF1 is an mTOR downstream effector and transcriptional repressor of ribosomal and transfer RNA genes. MAF1 expression is markedly reduced in hepatocellular carcinomas, which is correlated with disease progression and poor prognosis. Consistently, MAF1 displays tumor-suppressor activity toward in vitro and in vivo cancer models. Surprisingly, blocking the synthesis of ribosomal and transfer RNAs is insufficient to account for MAF1's tumor-suppressor function. Instead, MAF1 down-regulation paradoxically leads to activation of AKT-mTOR signaling, which is mediated by decreased PTEN expression. MAF1 binds to the PTEN promoter, enhancing PTEN promoter acetylation and activity. CONCLUSION In contrast to its canonical function as a transcriptional repressor, MAF1 can also act as a transcriptional activator for PTEN, which is important for MAF1's tumor-suppressor function. These results have implications in disease staging, prognostic prediction, and AKT-mTOR-targeted therapy in liver cancer. (Hepatology 2016;63:1928-1942).
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Affiliation(s)
- Yue Li
- State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer MedicineSun Yat‐sen University Cancer CenterGuangzhouChina
| | - Chi Kwan Tsang
- Rutgers Cancer Institute of New Jersey and Department of Pharmacology, Robert Wood Johnson Medical School, Rutgersthe State University of New JerseyNew BrunswickNJ
| | - Suihai Wang
- State Key Laboratory of Organ Failure Research, Institute of Antibody Engineering, School of BiotechnologySouthern Medical UniversityGuangzhouChina
| | - Xiao‐Xing Li
- State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer MedicineSun Yat‐sen University Cancer CenterGuangzhouChina
| | - Yang Yang
- State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer MedicineSun Yat‐sen University Cancer CenterGuangzhouChina
| | - Liwu Fu
- State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer MedicineSun Yat‐sen University Cancer CenterGuangzhouChina
| | - Wenlin Huang
- State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer MedicineSun Yat‐sen University Cancer CenterGuangzhouChina
| | - Ming Li
- State Key Laboratory of Organ Failure Research, Institute of Antibody Engineering, School of BiotechnologySouthern Medical UniversityGuangzhouChina
| | - Hui‐Yun Wang
- State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer MedicineSun Yat‐sen University Cancer CenterGuangzhouChina,Rutgers Cancer Institute of New Jersey and Department of Pharmacology, Robert Wood Johnson Medical School, Rutgersthe State University of New JerseyNew BrunswickNJ
| | - X.F. Steven Zheng
- State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer MedicineSun Yat‐sen University Cancer CenterGuangzhouChina,Rutgers Cancer Institute of New Jersey and Department of Pharmacology, Robert Wood Johnson Medical School, Rutgersthe State University of New JerseyNew BrunswickNJ
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18
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Zhong Q, Xi S, Liang J, Shi G, Huang Y, Zhang Y, Levy D, Zhong S. The significance of Brf1 overexpression in human hepatocellular carcinoma. Oncotarget 2016; 7:6243-54. [PMID: 26701855 PMCID: PMC4868753 DOI: 10.18632/oncotarget.6668] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2015] [Accepted: 12/07/2015] [Indexed: 02/05/2023] Open
Abstract
Brf1 (TFIIB-related factor 1) plays a crucial role in cell transformation and tumorigenesis. However, the significance of Brf1 expression in human HCC (hepatocellular carcinoma) cases remains to be addressed. In this study, biopsies of human HCC, liver tumor samples of mice and cell lines of normal and tumor liver were utilized to determine the alteration of Brf1 expression using cytological and molecular biological approaches. Brf1 expression is increased in human HCC cases, which is correlated with shorter survival times. Levels of Brf1 and Pol III (RNA polymerase III-dependent) gene transcription in HCC patients with alcohol consumption are higher than the cases of non-HCC with or without alcohol intake. Induction of Brf1 and Pol III genes by ethanol in hepatoma cells is higher than in non-tumor cells. Ethanol increases the rate of cell transformation. Repression of Brf1 inhibits alcohol-promoted cell transformation. Alcohol consumption enhances Brf1 expression to promote cell transformation. These studies demonstrate that Brf1 is a new biomarker of HCC.
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Affiliation(s)
- Qian Zhong
- State Key Laboratory of Oncology in South China, Sun Yat-sen University Cancer Center, Guangzhou, China
| | - Shaoyan Xi
- State Key Laboratory of Oncology in South China, Sun Yat-sen University Cancer Center, Guangzhou, China
| | - Jianzhong Liang
- State Key Laboratory of Oncology in South China, Sun Yat-sen University Cancer Center, Guangzhou, China
| | - Ganggang Shi
- Shantou University Medical College, Shantou, Guangdong, China
| | - Yi Huang
- Department of Biochemistry and Molecular Biology, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Yanmei Zhang
- Shantou University Medical College, Shantou, Guangdong, China
- Department of Biochemistry and Molecular Biology, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Daniel Levy
- Department of Biochemistry and Molecular Biology, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Shuping Zhong
- Shantou University Medical College, Shantou, Guangdong, China
- Department of Biochemistry and Molecular Biology, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
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RNA Polymerase III Output Is Functionally Linked to tRNA Dimethyl-G26 Modification. PLoS Genet 2015; 11:e1005671. [PMID: 26720005 PMCID: PMC4697793 DOI: 10.1371/journal.pgen.1005671] [Citation(s) in RCA: 67] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2015] [Accepted: 10/26/2015] [Indexed: 11/19/2022] Open
Abstract
Control of the differential abundance or activity of tRNAs can be important determinants of gene regulation. RNA polymerase (RNAP) III synthesizes all tRNAs in eukaryotes and it derepression is associated with cancer. Maf1 is a conserved general repressor of RNAP III under the control of the target of rapamycin (TOR) that acts to integrate transcriptional output and protein synthetic demand toward metabolic economy. Studies in budding yeast have indicated that the global tRNA gene activation that occurs with derepression of RNAP III via maf1-deletion is accompanied by a paradoxical loss of tRNA-mediated nonsense suppressor activity, manifested as an antisuppression phenotype, by an unknown mechanism. We show that maf1-antisuppression also occurs in the fission yeast S. pombe amidst general activation of RNAP III. We used tRNA-HydroSeq to document that little changes occurred in the relative levels of different tRNAs in maf1Δ cells. By contrast, the efficiency of N2,N2-dimethyl G26 (m(2)2G26) modification on certain tRNAs was decreased in response to maf1-deletion and associated with antisuppression, and was validated by other methods. Over-expression of Trm1, which produces m(2)2G26, reversed maf1-antisuppression. A model that emerges is that competition by increased tRNA levels in maf1Δ cells leads to m(2)2G26 hypomodification due to limiting Trm1, reducing the activity of suppressor-tRNASerUCA and accounting for antisuppression. Consistent with this, we show that RNAP III mutations associated with hypomyelinating leukodystrophy decrease tRNA transcription, increase m(2)2G26 efficiency and reverse antisuppression. Extending this more broadly, we show that a decrease in tRNA synthesis by treatment with rapamycin leads to increased m(2)2G26 modification and that this response is conserved among highly divergent yeasts and human cells.
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20
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The RNA-binding protein Sam68 regulates tumor cell viability and hepatic carcinogenesis by inhibiting the transcriptional activity of FOXOs. J Mol Histol 2015; 46:485-97. [PMID: 26438629 DOI: 10.1007/s10735-015-9639-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2015] [Accepted: 09/30/2015] [Indexed: 12/31/2022]
Abstract
Src associated in mitosis (Sam68; 68 kDa) is a KH domain RNA-binding protein that belongs to the signal transduction and activation of RNA family, and has been implicated in the oncogenesis and progression of several human cancers. Our study aimed to investigated the clinicopathologic significance of Sam68 expression and its role in cell proliferation and the underlying molecular mechanism in hepatocellular carcinoma (HCC). We demonstrated that Sam68 expression was significantly increased in HCC and high expression of Sam68 was significantly associated with Edmondson grade, tumor size, tumor nodule number, HBsAg status and Ki-67 expression. The Kaplan-Meier survival curves showed that increased expression of Sam68 was correlated with poor prognosis in HCC patients and served as an independent prognostic marker of overall survival in a multivariable analysis. In addition, through serum starvation and refeeding assay, we demonstrated that Sam68 was lowly expressed in serum-starved HCC cells, and was progressively increased after serum-additioning. Furthermore, siRNA knockdown of endogenous Sam68 inhibited cell proliferation and tumourigenicity of HCC cells in vitro, through blocking the G1 to S phase transition. Moreover, we reported that the anti-proliferative effect of silencing Sam68 was accompanied with up-regulated expression of cyclin-dependent kinase inhibitors, p21(Cip1) and p27(Kip1), enhanced transactivation of FOXO factors (FOXO4), and dysreuglation of Akt/GSK-3β signaling. Taken together, these findings provide a rational framework for the progression of HCC and thereby indicated that Sam68 might be a novel and useful prognostic marker and a potential target for human HCC treatment.
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21
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Wang Y, Liang L, Zhang J, Li M, Zhu J, Gong C, Yang L, Zhu J, Chen L, Ni R. Sam68 promotes cellular proliferation and predicts poor prognosis in esophageal squamous cell carcinoma. Tumour Biol 2015; 36:8735-45. [PMID: 26050229 DOI: 10.1007/s13277-015-3631-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2015] [Accepted: 05/31/2015] [Indexed: 12/14/2022] Open
Abstract
Sam68 (Src-associated in mitosis of 68 kD) is a KH domain RNA-binding protein. The expression of Sam68 was correlated with kinds of tumors. Yet, the expression mechanisms and physiological significance of Sam68 in ESCC remains unclear. In this study, we clarified a potential role of Sam68 in the treatment of ESCC. Western blot and immunohistochemistry (IHC) analysis revealed that the protein level of Sam68 was higher in ESCC tumor tissues and cell lines. In addition, IHC stain revealed that Sam68 was positively correlated with clinical pathologic variables such as tumor grade and tumor invasion. In addition, Sam68 could be an independent prognostic indicator for patients' overall survival. In vitro studies such as starvation and refeeding assay along with Sam68-shRNA transfection assay demonstrated that Sam68 expression promoted proliferation of ESCC cells. And Sam68 downregulation caused decreased rate of cell growth and colony formation. Reasons are associated with growth arrest of cell cycle at G1/S phase. Moreover, our results clarified that Sam68 could promote ESCC cell proliferation via the activation of Akt/GSK-3β pathway. This research indicated that Sam68 might accelerate the cell cycle progression and be considered as a new therapy target in ESCC.
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Affiliation(s)
- Yayun Wang
- Department of Gastroenterology, Affiliated Hospital of Nantong University, 19 Qixiu Road, Nantong, 226001, Jiangsu, China
| | - Li Liang
- Department of Medical Oncology, Affiliated Hospital of Nantong University, 19 Qixiu Road, Nantong, 226001, Jiangsu, China
| | - Jianguo Zhang
- Department of Pathology, Affiliated Hospital of Nantong University, 19 Qixiu Road, Nantong, 226001, Jiangsu, China
| | - Mei Li
- Department of Medical Oncology, Affiliated Hospital of Nantong University, 19 Qixiu Road, Nantong, 226001, Jiangsu, China
| | - Junya Zhu
- Department of Gastroenterology, Affiliated Hospital of Nantong University, 19 Qixiu Road, Nantong, 226001, Jiangsu, China
| | - Chen Gong
- Department of Gastroenterology, Affiliated Hospital of Nantong University, 19 Qixiu Road, Nantong, 226001, Jiangsu, China
| | - Linlin Yang
- Department of Oncology, Affiliated Cancer Hospital of Nantong University, Nantong, 226361, Jiangsu, China
| | - Jia Zhu
- Department of Oncology, Affiliated Cancer Hospital of Nantong University, Nantong, 226361, Jiangsu, China
| | - Lingling Chen
- Department of Gastroenterology, Affiliated Hospital of Nantong University, 19 Qixiu Road, Nantong, 226001, Jiangsu, China
| | - Runzhou Ni
- Department of Gastroenterology, Affiliated Hospital of Nantong University, 19 Qixiu Road, Nantong, 226001, Jiangsu, China.
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22
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Zhong Q, Shi G, Zhang Y, Lu L, Levy D, Zhong S. Alteration of BRCA1 expression affects alcohol-induced transcription of RNA Pol III-dependent genes. Gene 2015; 556:74-9. [PMID: 25447904 PMCID: PMC4272617 DOI: 10.1016/j.gene.2014.11.009] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2014] [Revised: 11/04/2014] [Accepted: 11/06/2014] [Indexed: 02/05/2023]
Abstract
Emerging evidence has indicated that alcohol consumption is an established risk factor for breast cancer. Deregulation of RNA polymerase III (Pol III) transcription enhances cellular Pol III gene production, leading to an increase in translational capacity to promote cell transformation and tumor formation. We have reported that alcohol intake increases Pol III gene transcription to promote cell transformation and tumor formation in vitro and in vivo. Studies revealed that tumor suppressors, pRb, p53, PTEN and Maf1 repress the transcription of Pol III genes. BRCA1 is a tumor suppressor and its mutation is tightly related to breast cancer development. However, it is not clear whether BRCA1 expression affects alcohol-induced transcription of Pol III genes. At the present studies, we report that restoring BRCA1 in HCC 1937 cells, which is a BRCA1 deficient cell line, represses Pol III gene transcription. Expressing mutant or truncated BRCA1 in these cells does not affect the ability of repression on Pol III genes. Our analysis has demonstrated that alcohol induces Pol III gene transcription. More importantly, overexpression of BRCA1 in estrogen receptor positive (ER+) breast cancer cells (MCF-7) decreases the induction of tRNA(Leu) and 5S rRNA genes by alcohol, whereas reduction of BRCA1 by its siRNA slightly increases the transcription of the class of genes. This suggests that BRCA1 is associated with alcohol-induced deregulation of Pol III genes. These studies for the first time demonstrate the role of BRCA1 in induction of Pol III genes by alcohol and uncover a novel mechanism of alcohol-associated breast cancer.
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Affiliation(s)
- Qian Zhong
- Department of Biochemistry and Molecular Biology, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA; State Key Laboratory of Oncology in South China, Sun Yat-sen University Cancer Center, China
| | - Ganggang Shi
- Shantou University Medical College, Shantou, Guangdong, China
| | - Yanmei Zhang
- Shantou University Medical College, Shantou, Guangdong, China
| | - Lei Lu
- Department of Biochemistry and Molecular Biology, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Daniel Levy
- Department of Biochemistry and Molecular Biology, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Shuping Zhong
- Department of Biochemistry and Molecular Biology, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA; Shantou University Medical College, Shantou, Guangdong, China.
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23
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Zhong Q, Shi G, Zhang Q, Lu L, Levy D, Zhong S. Tamoxifen represses alcohol-induced transcription of RNA polymerase III-dependent genes in breast cancer cells. Oncotarget 2014; 5:12410-7. [PMID: 25400119 PMCID: PMC4322994 DOI: 10.18632/oncotarget.2678] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2014] [Accepted: 11/04/2014] [Indexed: 02/05/2023] Open
Abstract
Alcohol consumption in women has been associated with an increased risk of breast cancer, particular in estrogen receptor positive (ER+) cases. Deregulation of RNA polymerase III-dependent (Pol III) transcription enhances cellular tRNAs and 5S rRNA production, leading to an increase in translational capacity to promote cell transformation and tumor formation. Our recent studies demonstrated that alcohol induces Brf1 expression and Pol III gene transcription via ER. Here, we report that Tamoxifen (Tam) inhibits the induction of Brf1 and Pol III genes in ER+ breast cancer cells. Further analysis indicates that alcohol increases c-Jun expression to upregulate the transcription of Brf1 and Pol III genes, whereas Tam reduces c-Jun expression to repress the transcription of Brf1. Repression of cJun decreases cellular levels of ERα and Brf1. Alcohol-dependent increased occupancy of Brf1 in Pol III gene promoters is reduced by Tam. The repression of Brf1 and Pol III genes by Tam reduces alcohol-induced cell proliferation and colony formation. Together, these results indicate that Tam inhibits alcohol-induced Brf1 expression through c-Jun and ERα to downregulate Pol III gene transcription. Our studies uncover a new mechanism of Tam-treated ER+ breast cancer, by which Tam inhibits tumor growth through repressing Pol III gene transcription.
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Affiliation(s)
- Qian Zhong
- Department of Biochemistry and Molecular Biology, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
- State Key Laboratory of Oncology in South China, Sun Yat-sen University Cancer Center, China
| | - Ganggang Shi
- Shantou University Medical College, Shantou, Guangdong, China
| | - Qingsong Zhang
- Department of Biochemistry and Molecular Biology, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Lei Lu
- Department of Biochemistry and Molecular Biology, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Daniel Levy
- Department of Biochemistry and Molecular Biology, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Shuping Zhong
- Department of Biochemistry and Molecular Biology, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
- Shantou University Medical College, Shantou, Guangdong, China
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Palian BM, Rohira AD, Johnson SAS, He L, Zheng N, Dubeau L, Stiles BL, Johnson DL. Maf1 is a novel target of PTEN and PI3K signaling that negatively regulates oncogenesis and lipid metabolism. PLoS Genet 2014; 10:e1004789. [PMID: 25502566 PMCID: PMC4263377 DOI: 10.1371/journal.pgen.1004789] [Citation(s) in RCA: 65] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2014] [Accepted: 09/30/2014] [Indexed: 12/16/2022] Open
Abstract
Maf1 was initially identified as a transcriptional repressor of RNA pol III-transcribed genes, yet little is known about its other potential target genes or its biological function. Here, we show that Maf1 is a key downstream target of PTEN that drives both its tumor suppressor and metabolic functions. Maf1 expression is diminished with loss of PTEN in both mouse models and human cancers. Consistent with its role as a tumor suppressor, Maf1 reduces anchorage-independent growth and tumor formation in mice. PTEN-mediated changes in Maf1 expression are mediated by PTEN acting on PI3K/AKT/FoxO1 signaling, revealing a new pathway that regulates RNA pol III-dependent genes. This regulatory event is biologically relevant as diet-induced PI3K activation reduces Maf1 expression in mouse liver. We further identify lipogenic enzymes as a new class of Maf1-regulated genes whereby Maf1 occupancy at the FASN promoter opposes SREBP1c-mediated transcription activation. Consistent with these findings, Maf1 inhibits intracellular lipid accumulation and increasing Maf1 expression in mouse liver abrogates diet-mediated induction of lipogenic enzymes and triglycerides. Together, these results establish a new biological role for Maf1 as a downstream effector of PTEN/PI3K signaling and reveal that Maf1 is a key element by which this pathway co-regulates lipid metabolism and oncogenesis. Obesity is a strong risk factor for human cancers, yet the biological basis for this is unclear. In addition to aberrant growth, abnormal lipid synthesis is a hallmark of cancer cells. Our results have identified a novel role for Maf1 in suppressing both lipid biogenesis and tumor formation. Maf1 elicits these biological responses through its ability to repress genes that that synthesize lipids and regulate biosynthetic capacity. Maf1 amounts are regulated through a critical cellular pathway involving PTEN/PI3K/Akt/FoxO1, which is deregulated in many human cancers. Our results support the idea that deregulation of this pathway in cancer cells results in decreases in cellular Maf1, resulting in both abnormal growth and lipid synthesis. Thus, Maf1 represents a novel link between lipid metabolism and oncogenic transformation providing a new molecular basis for the strong association between obesity and cancer.
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Affiliation(s)
- Beth M. Palian
- Department of Biochemistry and Molecular Biology, Keck School of Medicine, University of Southern California, and the Norris Comprehensive Cancer Center, Los Angeles, California, United States of America
| | - Aarti D. Rohira
- Department of Biochemistry and Molecular Biology, Keck School of Medicine, University of Southern California, and the Norris Comprehensive Cancer Center, Los Angeles, California, United States of America
| | - Sandra A. S. Johnson
- Department of Biochemistry and Molecular Biology, Keck School of Medicine, University of Southern California, and the Norris Comprehensive Cancer Center, Los Angeles, California, United States of America
| | - Lina He
- Department of Pharmaceutical Sciences, School of Pharmacy, Keck School of Medicine, University of Southern California, and the Norris Comprehensive Cancer Center, Los Angeles, California, United States of America
| | - Ni Zheng
- Department of Pharmaceutical Sciences, School of Pharmacy, Keck School of Medicine, University of Southern California, and the Norris Comprehensive Cancer Center, Los Angeles, California, United States of America
| | - Louis Dubeau
- Department of Pathology, Keck School of Medicine, University of Southern California, and the Norris Comprehensive Cancer Center, Los Angeles, California, United States of America
| | - Bangyan L. Stiles
- Department of Pharmaceutical Sciences, School of Pharmacy, Keck School of Medicine, University of Southern California, and the Norris Comprehensive Cancer Center, Los Angeles, California, United States of America
| | - Deborah L. Johnson
- Department of Biochemistry and Molecular Biology, Keck School of Medicine, University of Southern California, and the Norris Comprehensive Cancer Center, Los Angeles, California, United States of America
- * E-mail:
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25
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Zhong Q, Shi G, Zhang Q, Zhang Y, Levy D, Zhong S. Role of phosphorylated histone H3 serine 10 in DEN-induced deregulation of Pol III genes and cell proliferation and transformation. Carcinogenesis 2013; 34:2460-9. [PMID: 23774401 DOI: 10.1093/carcin/bgt219] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The products of Pol III genes (RNA polymerase III-dependent genes), such as tRNAs and 5S rRNA, are elevated in both transformed and tumor cells suggesting that they play a crucial role in tumorigenesis. An increase in Brf1 (TFIIIB-related factor 1), a subunit of TFIIIB, augments Pol III gene transcription and is sufficient for cell transformation and tumor formation. We have demonstrated that enhancement of Brf1 and Pol III gene expression is associated with the occurrences of hepatocellular carcinoma (HCC) in mice. This suggests that Brf1 may be a key molecule during HCC development. Diethylnitrosamine (DEN), a chemical carcinogen, has been used to induce HCC in rodents. To determine the role of Brf1 and the epigenetic-regulating events in cell proliferation and transformation, hepatocytes were treated with DEN. The results indicate that DEN increases proliferation and transformation of AML-12 cells. DEN enhanced Brf1 expression and tRNA(Leu) and 5S rRNA transcription, as well as H3S10ph (phosphorylation of histone H3 serine 10). Interestingly, DEN-induced Pol III gene transcription and H3S10ph in tumor cells of liver are significantly higher than in non-tumor cells. Inhibition of H3S10ph by H3S10A attenuates the induction of Brf1 and Pol III genes. Further analysis indicates that H3S10ph occupies the promoters of Brf1 and Pol III genes to modulate their expression. Blocking H3S10ph represses cell proliferation and transformation. These results demonstrate that DEN induces H3S10ph, which mediate Brf1 expression, including but not limited Brf1-dependent genes, to upregulate Pol III gene transcription, resulting in an increase in cell proliferation and transformation.
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Affiliation(s)
- Qian Zhong
- Department of Biochemistry and Molecular Biology, Keck School of Medicine, University of Southern California, 2011 Zonal Avenue, HMR 605, Los Angeles, CA 90033, USA
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Rohira AD, Chen CY, Allen JR, Johnson DL. Covalent small ubiquitin-like modifier (SUMO) modification of Maf1 protein controls RNA polymerase III-dependent transcription repression. J Biol Chem 2013; 288:19288-95. [PMID: 23673667 DOI: 10.1074/jbc.m113.473744] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
RNA polymerase (pol) III transcribes genes that determine biosynthetic capacity. Induction of these genes is required for oncogenic transformation. The transcriptional repressor, Maf1, plays a central role in the repression of these and other genes that promote oncogenesis. Our studies identify an important new role for SUMOylation in repressing RNA pol III-dependent transcription. We show that a key mechanism by which this occurs is through small ubiquitin-like modifier (SUMO) modification of Maf1 by both SUMO1 and SUMO2. Mutation of each lysine residue revealed that Lys-35 is the major SUMOylation site on Maf1 and that the deSUMOylase, SENP1, is responsible for controlling Maf1K35 SUMOylation. SUMOylation of Maf1 is unaffected by rapamycin inhibition of mammalian target of rapamycin (mTOR) and mTOR-dependent Maf1 phosphorylation. By preventing SUMOylation at Lys-35, Maf1 is impaired in its ability to both repress transcription and suppress colony growth. Although SUMOylation does not alter Maf1 subcellular localization, Maf1K35R is defective in its ability to associate with RNA pol III. This impairs Maf1 recruitment to tRNA gene promoters and its ability to facilitate the dissociation of RNA pol III from these promoters. These studies identify a novel role for SUMOylation in controlling Maf1 and RNA pol III-mediated transcription. Given the emerging roles of SENP1, Maf1, and RNA pol III transcription in oncogenesis, our studies support the idea that deSUMOylation of Maf1 and induction of its gene targets play a critical role in cancer development.
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Affiliation(s)
- Aarti D Rohira
- Department of Biochemistry and Molecular Biology, Keck School of Medicine, University of Southern California and the Norris Comprehensive Cancer Center, Los Angeles, California 90033, USA
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Elk1 and AP-1 sites in the TBP promoter mediate alcohol-induced deregulation of Pol III-dependent genes. Gene 2013; 526:54-60. [PMID: 23454483 DOI: 10.1016/j.gene.2013.02.004] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2012] [Revised: 02/05/2013] [Accepted: 02/08/2013] [Indexed: 01/22/2023]
Abstract
The major risk factors for hepatocellular carcinoma (HCC) are chronic liver diseases that include hepatitis B, hepatitis C, alcoholic liver disease and non-alcoholic steatohepatitis. However, the mechanisms of alcohol-associated HCC remain to be elucidated. The products of RNA Pol III (RNA polymerase III) dependent genes are elevated in both transformation cells and tumor cells. TBP (TATA-box binding protein) is a central transcription factor, which regulates Pol I, Pol II and Pol III gene activity. Our studies have demonstrated that alcohol increases TBP expression and Pol III gene transcription to promote liver tumor formation. We continue to investigate how ethanol mediates TBP expression. Here, we report that ethanol induces TBP promoter activity and the induction is ethanol dose dependent. Blocking the JNK1 pathway by a chemical inhibitor and siRNA reduces this ethanol-induced activity. Furthermore, mutating G>A at a -46 bp Elk1 binding site of the TBP promoter or mutating AP-1 binding site at -37 bp (A>G) and -38 bp (C>T) reduces the TBP promoter activity. Mutation of both Elk1 and AP-1 binding sites dramatically represses this induction. Together, these studies demonstrate that, for the first time, alcohol increases Pol III gene transcription through a response element, which is composed of the overlapping Elk1 and AP-1 binding sites of the TBP promoter and affected by alcohol. It suggests that these binding sites may play a critical role in alcohol-induced deregulation of Pol III genes in liver tumor development.
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28
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Zhang Q, Jin J, Zhong Q, Yu X, Levy D, Zhong S. ERα mediates alcohol-induced deregulation of Pol III genes in breast cancer cells. Carcinogenesis 2012; 34:28-37. [PMID: 23054611 DOI: 10.1093/carcin/bgs316] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
The association of alcohol consumption and breast cancer is more pronounced in cases that are positive for estrogen receptor (ER+) than in cases that are negative (ER-). Its mechanism remains to be determined. Deregulation of RNA polymerase III (Pol III) transcription enhances cellular tRNAs and 5S rRNA production, increasing translational capacity to promote cell transformation and tumor formation. Here, we report that alcohol increases Pol III gene transcription in both normal and cancer breast cell lines. The induction in ER+ breast cancer cells (MCF-7) is significantly higher than in ER- normal breast cells (MCF-10A, MCF-10F and MCF-12A) and is correlated with ER expression. E2 causes <2-fold increase in Pol III gene transcription. The addition of ethanol to this system now produces a 10-15-fold increase. Ethanol increases ERα expression, resulting in an increase in Brf1 protein and mRNA levels. In addition, ethanol markedly stimulates phosphorylation of JNK1, but not JNK2. Inhibition of JNK1 decreases ERE-Luc reporter activity and represses expression of ERα, Brf1 and Pol III genes. Reduction of ERα by its small interfering RNA represses Brf1 and Pol III gene transcription. Ethanol with E2 produces larger and more numerous colonies. Repression of ERα or Brf1 inhibits alcohol-induced cell transformation. Together, these results support the idea that alcohol increases ERα expression through JNK1 to elevate Brf1 expression and Pol III gene transcription to bring about greater phenotypic changes. These studies demonstrate that ERα mediates Pol III gene transcription through Brf1, suggesting that ERα may play a critical role in alcohol-induced deregulation of Pol III genes in ER+ breast cancer development.
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Affiliation(s)
- Qingsong Zhang
- Department of Biochemistry and Molecular Biology, Keck School of Medicine, University of Southern California, Los Angeles, CA 90033, USA
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29
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Vannini A. A structural perspective on RNA polymerase I and RNA polymerase III transcription machineries. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2012; 1829:258-64. [PMID: 23031840 DOI: 10.1016/j.bbagrm.2012.09.009] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/13/2012] [Revised: 09/17/2012] [Accepted: 09/21/2012] [Indexed: 01/11/2023]
Abstract
RNA polymerase I and III are responsible for the bulk of nuclear transcription in actively growing cells and their activity impacts the cellular biosynthetic capacity. As a consequence, RNA polymerase I and III deregulation has been directly linked to cancer development. The complexity of RNA polymerase I and III transcription apparatuses has hampered their structural characterization. However, in the last decade tremendous progresses have been made, providing insights into the molecular and functional architecture of these multi-subunit transcriptional machineries. Here we summarize the available structural data on RNA polymerase I and III, including specific transcription factors and global regulators. Despite the overall scarcity of detailed structural data, the recent advances in the structural biology of RNA polymerase I and III represent the first step towards a comprehensive understanding of the molecular mechanism underlying RNA polymerase I and III transcription. This article is part of a Special Issue entitled: Transcription by Odd Pols.
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Affiliation(s)
- Alessandro Vannini
- Division of Structural Biology, Institute of Cancer Research, Chester Beatty Laboratories, 237 Fulham Road, London SW3 6JB, UK.
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30
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Abstract
Deregulation of RNA polymerase III (Pol III) transcription enhances cellular tRNAs and 5S rRNA production, leading to an increase in translational capacity to promote cell proliferation, transformation and tumor formation. Phosphorylation of histone H3 (H3ph) is induced by tumor promoters (EGF, UV and TPA) and immediate early genes, such as c-myc, c-jun and c-fos. However, it remains to be determined whether H3ph is involved in RNA Pol III transcription. Here, we report that EGF strongly induced H3ph at serine 28 (H3S28ph). EGF significantly increased transcription of RNA Pol III-dependent genes (Pol III genes), tRNALeu, tRNATyr, 5S rRNA, and 7SL RNA. Inhibition of EGFR, but not PI3K, reduced both H3S28ph and tRNALeu and 5S rRNA transcription. EGF enhanced occupancy of H3S28ph in the promoters of tRNALeu and 5S rRNA. Further analysis indicates that EGF augmented cellular levels of protein and mRNA of TFIIIB subunits, Brf1 and TBP. Brf1 is a specific transcription factor for RNA Pol III genes. EGF enhanced occupancy of H3S28ph in the Brf1 and TBP promoters. Inhibition of H3S28ph by mutant H3S28A repressed Brf1, TBP and tRNALeu and 5S rRNA expression and decreased occupancy of H3S28ph in their promoters. Reduction of Brf1 significantly decreased tRNALeu and 5S rRNA transcription and repressed EGF-induced anchorage-independent growth. Blocking H3S28ph signaling by using mutant H3S28A reduced EGF-induced cell transformation. Together, these results indicate that EGF activates EGFR signaling to induce H3S28ph, which, in turn, upregulates tRNALeu and 5S rRNA transcription through Brf1 and TBP and promotes cell transformation. The studies demonstrate that epigenetic modification of H3S28ph plays a critical role in the activity of Pol III genes.
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31
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Zhong S, Machida K, Tsukamoto H, Johnson DL. Alcohol induces RNA polymerase III-dependent transcription through c-Jun by co-regulating TATA-binding protein (TBP) and Brf1 expression. J Biol Chem 2010; 286:2393-401. [PMID: 21106530 DOI: 10.1074/jbc.m110.192955] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Chronic alcohol consumption is associated with steatohepatitis and cirrhosis, enhancing the risk for hepatocellular carcinoma. RNA polymerase (pol) III transcribes a variety of small, untranslated RNAs, including tRNAs and 5S rRNAs, which determine the biosynthetic capacity of cells. Increased RNA pol III-dependent transcription, observed in transformed cells and human tumors, is required for oncogenic transformation. Given that alcohol consumption increases risk for liver cancer, we examined whether alcohol regulates this class of genes. Ethanol induces RNA pol III-dependent transcription in both HepG2 cells and primary mouse hepatocytes in a manner that requires ethanol metabolism and the activation of JNK1. This regulatory event is mediated, at least in part, through the ability of ethanol to induce expression of the TFIIIB components, Brf1, and the TATA-binding protein (TBP). Induction of TBP, Brf1, and RNA pol III-dependent gene expression is driven by enhanced c-Jun expression. Ethanol promotes a marked increase in the direct recruitment of c-Jun to TBP, Brf1, and tRNA gene promoters. Chronic alcohol administration in mice leads to enhanced expression of TBP, Brf1, tRNA, and 5S rRNA gene transcription in the liver. These alcohol-dependent increases are more pronounced in transgenic animals that express the HCV NS5A protein that display increased incidence of liver tumors. Together, these results identify a new class of genes that are regulated by alcohol through the co-regulation of TFIIIB components and define a central role for c-Jun in this process.
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Affiliation(s)
- Shuping Zhong
- Department of Biochemistry and Molecular Biology and the Norris Comprehensive Cancer Center, University of Southern California, Los Angeles, California 90033, USA.
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32
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Song L, Wang L, Li Y, Xiong H, Wu J, Li J, Li M. Sam68 up-regulation correlates with, and its down-regulation inhibits, proliferation and tumourigenicity of breast cancer cells. J Pathol 2010; 222:227-37. [PMID: 20662004 DOI: 10.1002/path.2751] [Citation(s) in RCA: 82] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
The biosynthesis and metabolism of RNA play important roles in regulating gene expression. On the other hand, it has been shown that RNA expression profiling is differentially distinct between cancer and normal cells, suggesting the possibility that aberrant regulation of RNA metabolism might be associated with the development and progression of cancer. In the current study, we found that Sam68, an RNA-binding protein that links cellular signalling to RNA processing, was markedly overexpressed in breast cancer cells and tissues. Immunohistochemical analysis showed that the expression and cytoplasmic localization of Sam68 significantly correlated with clinical characteristics of patients, including clinical stage, tumour-nodule-metastasis (TNM) classification, histological grade, and ER expression. Univariate and multivariate analyses showed that the expression level and cytoplasmic localization of Sam68 were identified as independent prognostic factors. Furthermore, we found that siRNA knockdown of endogenous Sam68 inhibited cell proliferation and tumourigenicity of breast cancer cells in vitro, through blocking the G1 to S phase transition. Moreover, we demonstrated that the anti-proliferative effect of silencing Sam68 on breast cancer cells was associated with up-regulation of cyclin-dependent kinase inhibitor p21(Cip1) and p27(Kip1), enhanced transactivation of FOXO factors, and attenuation of Akt/GSK-3β signalling. Taken together, our results suggest that Sam68 might play an important role in promoting the proliferation and carcinogenesis of human breast cancer, and thereby might be a novel and useful prognostic marker and a potential target for human breast cancer treatment.
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Affiliation(s)
- Libing Song
- State Key Laboratory of Oncology in Southern China, Department of Experimental Research, Cancer Center, Sun Yat-sen University, Guangzhou, Guangdong, China.
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33
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Clelland BW, Schultz MC. Genome stability control by checkpoint regulation of tRNA gene transcription. Transcription 2010; 1:115-125. [PMID: 21326884 DOI: 10.4161/trns.1.3.13735] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2010] [Revised: 08/31/2010] [Accepted: 09/23/2010] [Indexed: 12/21/2022] Open
Abstract
The RNA polymerase III pre-initiation complex (PIC) assembled on yeast tRNA genes naturally causes replication fork pausing that contributes to genome instability. Mechanistic coupling of the fork pausing activity of tRNA genes to replication has long been considered likely, but only recently demonstrated. In contrast to the expectation that this coupling might occur by a passive mechanism such as direct disruption of transcription factor-DNA complexes by a component of the replisome, it turns out that disassembly of the RNA polymerase III PIC is actively controlled by the replication stress checkpoint signal transduction pathway. This advance supports a new model in which checkpoint-dependent disassembly of the transcription machinery at tRNA genes is a vital component of an overall system of genome stability control that also targets replication and DNA repair proteins.
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Affiliation(s)
- Brett W Clelland
- Department of Biochemistry; School of Molecular and Systems Medicine; University of Alberta; Edmonton, AB Canada
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Athineos D, Marshall L, White RJ. Regulation of TFIIIB during F9 cell differentiation. BMC Mol Biol 2010; 11:21. [PMID: 20226026 PMCID: PMC2842266 DOI: 10.1186/1471-2199-11-21] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2009] [Accepted: 03/12/2010] [Indexed: 01/04/2023] Open
Abstract
BACKGROUND Differentiation of F9 embryonal carcinoma (EC) cells into parietal endoderm (PE) provides a tractable model system for studying molecular events during early and inaccessible stages of murine development. PE formation is accompanied by extensive changes in gene expression both in vivo and in culture. One of the most dramatic is the ~10-fold decrease in transcriptional output by RNA polymerase (pol) III. This has been attributed to changes in activity of TFIIIB, a factor that is necessary and sufficient to recruit pol III to promoters. The goal of this study was to identify molecular changes that can account for the low activity of TFIIIB following F9 cell differentiation. RESULTS Three essential subunits of TFIIIB decrease in abundance as F9 cells differentiate; these are Brf1 and Bdp1, which are pol III-specific, and TBP, which is also used by pols I and II. The decreased levels of Brf1 and Bdp1 proteins can be explained by reduced expression of the corresponding mRNAs. However, this is not the case for TBP, which is regulated post-transcriptionally. In proliferating cells, pol III transcription is stimulated by the proto-oncogene product c-Myc and the mitogen-activated protein kinase Erk, both of which bind to TFIIIB. However, c-Myc levels fall during differentiation and Erk becomes inactive through dephosphorylation. The diminished abundance of TFIIIB is therefore likely to be compounded by changes to these positive regulators that are required for its full activity. In addition, PE cells have elevated levels of the retinoblastoma protein RB, which is known to bind and repress TFIIIB. CONCLUSION The low activity of TFIIIB in PE can be attributed to a combination of changes, any one of which could be sufficient to inhibit pol III transcription. Declining levels of essential TFIIIB subunits and of activators that are required for maximal TFIIIB activity are accompanied by an increase in a potent repressor of TFIIIB. These events provide fail-safe guarantees to ensure that pol III output is appropriate to the diminished metabolic requirements of terminally differentiated cells.
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Affiliation(s)
- Dimitris Athineos
- Beatson Institute for Cancer Research, Garscube Estate, Switchback Road, Bearsden, Glasgow G61 1BD, UK
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35
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Tsang CK, Liu H, Zheng XFS. mTOR binds to the promoters of RNA polymerase I- and III-transcribed genes. Cell Cycle 2010; 9:953-7. [PMID: 20038818 DOI: 10.4161/cc.9.5.10876] [Citation(s) in RCA: 119] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Target of rapamycin (TOR) is a conserved regulator of gene expression from yeast to humans. In budding yeast, TOR is associated with ribosomal DNA (rDNA) promoter, which is critical for ribosome biogenesis and transfer RNA (tRNA) synthesis. Whether mTOR behaves similarly in mammalian cells is unknown. Here, we report that mTOR is detected at several different promoters in human and murine cells, including that of rDNA and tRNA genes. The association of mTOR with these promoters is regulated by growth signals and sensitive to rapamycin. Together, our observations suggest that mTOR is closely involved in gene regulation at the promoters, which is a conserved mechanism to control RNA polymerase I- and III-dependent genes that are critical for protein synthesis and cell growth.
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Affiliation(s)
- Chi Kwan Tsang
- Department of Pharmacology and Cancer Institute of New Jersey, Robert Wood Johnson Medical School, Piscataway, NJ, USA
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36
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Abstract
RNA transcription by all the three RNA polymerases (RNAPs) is tightly controlled, and loss of regulation can lead to, for example, cellular transformation and cancer. While most transcription factors act specifically with one polymerase, a small number have been shown to affect more than one polymerase to coordinate overall levels of transcription in cells. Here we show that TLS (translocated in liposarcoma), a protein originally identified as the product of a chromosomal translocation and which associates with both RNAP II and the spliceosome, also represses transcription by RNAP III. TLS was found to repress transcription from all three classes of RNAP III promoters in vitro and to associate with RNAP III genes in vivo, perhaps via a direct interaction with the pan-specific transcription factor TATA-binding protein (TBP). Depletion of TLS by small interfering RNA (siRNA) in HeLa cells resulted in increased steady-state levels of RNAP III transcripts as well as increased RNAP III and TBP occupancy at RNAP III-transcribed genes. Conversely, overexpression of TLS decreased accumulation of RNAP III transcripts. These unexpected findings indicate that TLS regulates both RNAPs II and III and supports the possibility that cross-regulation between RNA polymerases is important in maintaining normal cell growth.
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37
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Wei Y, Zheng XFS. Sch9 partially mediates TORC1 signaling to control ribosomal RNA synthesis. Cell Cycle 2009; 8:4085-90. [PMID: 19823048 DOI: 10.4161/cc.8.24.10170] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
TORC1 is a central regulator of ribosomal RNA synthesis. Here we report that Sch9 partially mediates TORC1 signaling to regulate Pol I- and Pol III-dependent transcription. Mechanistically, Sch9 is involved in hyperphosphorylation and cytoplasmic localization of Maf1, and for optimal synthesis of rRNAs and tRNAs. Interestingly, sch9Delta does not affect Maf1 basal phosphorylation and nucleolar localization. In addition, TORC1 is still capable of regulating rRNAs and tRNAs in the absence of Sch9. Moreover, the hyperactive Sch9(2D3E) mutant does not confer significant rapamycin resistance in cell growth. Together, these observations indicate that Sch9 is involved in optimal regulation of ribosome biogenesis by TORC1, but is dispensable for the essential aspects of ribosome biogenesis and cell growth, suggesting that TORC1 controls cell growth through Sch9-dependent and independent mechanisms.
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Affiliation(s)
- Yuehua Wei
- Graduate Program in Cellular and Molecular Pharmacology, UMDNJ-Robert Wood Johnson Medical School, Piscataway, NJ, USA
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38
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Kantidakis T, White RJ. Dr1 (NC2) is present at tRNA genes and represses their transcription in human cells. Nucleic Acids Res 2009; 38:1228-39. [PMID: 19965767 PMCID: PMC2831321 DOI: 10.1093/nar/gkp1102] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Dr1 (also known as NC2β) was identified as a repressor of RNA polymerase (pol) II transcription. It was subsequently shown to inhibit pol III transcription when expressed at high levels in vitro or in yeast cells. However, endogenous Dr1 was not detected at pol III-transcribed genes in growing yeast. In contrast, we demonstrate that endogenous Dr1 is present at pol III templates in human cells, as is its dimerization partner DRAP1 (also called NC2α). Expression of tRNA by pol III is selectively enhanced by RNAi-mediated depletion of endogenous human Dr1, but we found no evidence that DRAP1 influences pol III output in vivo. A stable association was detected between endogenous Dr1 and the pol III-specific transcription factor Brf1. This interaction may recruit Dr1 to pol III templates in vivo, as crosslinking to these sites increases following Brf1 induction. On the basis of these data, we conclude that the physiological functions of human Dr1 include regulation of pol III transcription.
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Affiliation(s)
- Theodoros Kantidakis
- Beatson Institute for Cancer Research, Garscube Estate, Switchback Road, Bearsden, Glasgow, G61 1BD, UK
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Mitkevich VA, Tchurikov NA, Zelenikhin PV, Petrushanko IY, Makarov AA, Ilinskaya ON. Binase cleaves cellular noncoding RNAs and affects coding mRNAs. FEBS J 2009; 277:186-96. [DOI: 10.1111/j.1742-4658.2009.07471.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Genomic gain of 5p15 leads to over-expression of Misu (NSUN2) in breast cancer. Cancer Lett 2009; 289:71-80. [PMID: 19740597 DOI: 10.1016/j.canlet.2009.08.004] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2009] [Revised: 07/21/2009] [Accepted: 08/02/2009] [Indexed: 12/28/2022]
Abstract
We have examined expression of the Myc target gene Misu (NSUN2) in breast cancer. There was extensive copy number gain, and increased mRNA and protein levels, of Misu in approximately one third of breast cancer cell lines and primary tumours examined, irrespective of tumour subtype. Genes on 5p15.31-33, where Misu is located, showed evolutionary synteny. siRNA-mediated knockdown of Misu reduced cell number in over half of the cell lines tested, irrespective of estrogen receptor status. We conclude that Misu is up-regulated in a substantial proportion of breast cancers and has therapeutic potential as a drug target.
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Blank M, Goodman R. Electromagnetic fields stress living cells. PATHOPHYSIOLOGY 2009; 16:71-8. [DOI: 10.1016/j.pathophys.2009.01.006] [Citation(s) in RCA: 85] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2009] [Accepted: 01/30/2009] [Indexed: 10/21/2022] Open
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The JNKs differentially regulate RNA polymerase III transcription by coordinately modulating the expression of all TFIIIB subunits. Proc Natl Acad Sci U S A 2009; 106:12682-7. [PMID: 19620725 DOI: 10.1073/pnas.0904843106] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
RNA polymerase (pol) III-dependent transcription is subject to stringent regulation by tumor suppressors and oncogenic proteins and enhanced RNA pol III transcription is essential for cellular transformation and tumorigenesis. Since the c-Jun N-terminal kinases (JNKs) display both oncogenic and tumor suppressor properties, the roles of these proteins in regulating RNA pol III transcription were examined. In both mouse and human cells, loss or reduction in JNK1 expression represses RNA pol III transcription. In contrast, loss or reduction in JNK2 expression induces transcription. The JNKs coordinately regulate expression of all 3 TFIIIB subunits. While JNK1 positively regulates TBP expression, the RNA pol III-specific factors, Brf1 and Bdp1, JNK2 negatively regulates their expression. Brf1 is coregulated with TBP through the JNK target, Elk-1. Reducing Elk-1 expression decreases Brf1 expression. Decreasing JNK1 expression reduces Elk-1 occupancy at the Brf1 promoter, while decreasing JNK2 expression enhances recruitment of Elk-1 to the Brf1 promoter. In contrast, regulation of Bdp1 occurs through JNK-mediated alterations in TBP expression. Altered TBP expression mimics the effect of reduced JNK1 or JNK2 levels on Bdp1 expression. Decreasing JNK1 expression reduces the occupancy of TBP at the Bdp1 promoter, while decreasing JNK2 expression enhances recruitment of TBP to the Bdp1 promoter. Together, these results provide a molecular mechanism for regulating RNA pol III transcription through the coordinate control of TFIIIB subunit expression and elucidate opposing functions for the JNKs in regulating a large class of genes that dictate the biosynthetic capacity of cells.
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Wei Y, Tsang CK, Zheng XFS. Mechanisms of regulation of RNA polymerase III-dependent transcription by TORC1. EMBO J 2009; 28:2220-30. [PMID: 19574957 DOI: 10.1038/emboj.2009.179] [Citation(s) in RCA: 126] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2009] [Accepted: 05/29/2009] [Indexed: 12/27/2022] Open
Abstract
We have found earlier that Tor1 binds to 5S rDNA chromatin but the functional significance has not been established. Here, we show that association with 5S rDNA chromatin is necessary for TOR complex 1 (TORC1) to regulate the synthesis of 5S ribosomal RNA and transfer RNAs (tRNAs) by RNA polymerase (Pol) III, as well as the phosphorylation and binding to Pol III-transcribed genes of the Pol III repressor Maf1. Interestingly, TORC1 does not bind to tRNA genes, suggesting that TORC1 modulates tRNA synthesis indirectly through Maf1 phosphorylation at the rDNA loci. We also find that Maf1 cytoplasmic localization is dependent on the SSD1-v allele. In W303 cells that carry the SSD1-d allele, Maf1 is constitutively nuclear but its nucleolar localization is inhibited by TORC1, indicating that TORC1 regulates nucleoplasm-to-nucleolus transport of Maf1. Finally, we show that TORC1 interacts with Maf1 in vivo and phosphorylates Maf1 in vitro, and regulates Maf1 nucleoplasm-to-nucleolus translocation. Together, these observations provide new insights into the chromatin-dependent mechanism by which TORC1 controls transcription by Pol III.
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Affiliation(s)
- Yuehua Wei
- Graduate Program in Cellular and Molecular Pharmacology, UMDNJ-Robert Wood Johnson Medical School, Piscataway, NJ, USA
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