title: Ras-induced epigenetic inactivation of the RRAD (Ras-related associated with diabetes) gene promotes glucose uptake in a human ovarian cancer model.
abstract: RRAD (Ras-related associated with diabetes) is a small Ras-related GTPase that is frequently inactivated by DNA methylation of the CpG island in its promoter region in cancer tissues. However, the role of the methylation-induced RRAD inactivation in tumorigenesis remains unclear. In this study, the Ras-regulated transcriptome and epigenome were profiled by comparing T29H (a Ras(V12)-transformed human ovarian epithelial cell line) with T29 (an immortalized but non-transformed cell line) through reduced representation bisulfite sequencing and digital gene expression. We found that Ras(V12)-mediated oncogenic transformation was accompanied by RRAD promoter hypermethylation and a concomitant loss of RRAD expression. In addition, we found that the RRAD promoter was hypermethylated, and its transcription was reduced in ovarian cancer versus normal ovarian tissues. Treatment with the DNA methyltransferase inhibitor 5-aza-2'-deoxycytidine resulted in demethylation in the RRAD promoter and restored RRAD expression in T29H cells. Additionally, treatment with farnesyltransferase inhibitor FTI277 resulted in restored RRAD expression and inhibited DNA methytransferase expression and activity in T29H cells. By employing knockdown and overexpression techniques in T29 and T29H, respectively, we found that RRAD inhibited glucose uptake and lactate production by repressing the expression of glucose transporters. Finally, RRAD overexpression in T29H cells inhibited tumor formation in nude mice, suggesting that RRAD is a tumor suppressor gene. Our results indicate that Ras(V12)-mediated oncogenic transformation induces RRAD epigenetic inactivation, which in turn promotes glucose uptake and may contribute to ovarian cancer tumorigenesis.
authors.affiliation: From the Institute of Psychology, Chinese Academy of Sciences, Beijing 100101, China, the University of the Chinese Academy of Sciences, Beijing 100080, China.
authors.forename: Yan
authors.initials: Y
authors.lastname: Wang
authors.affiliation: the Institute of Genomic Medicine, Wenzhou Medical University, 268 West Xueyuan Road, Wenzhou, Zhejiang Province 325000, China.
authors.forename: Guiling
authors.initials: G
authors.lastname: Li
authors.affiliation: the University of the Chinese Academy of Sciences, Beijing 100080, China, the Beijing Institutes of Life Science, Chinese Academy of Sciences, Beijing 100101, China.
authors.forename: Fengbiao
authors.initials: F
authors.lastname: Mao
authors.affiliation: the State Key Laboratory of Medical Genetics, Central South University, Changsha, Hunan Province 410078, China, and.
authors.forename: Xianfeng
authors.initials: X
authors.lastname: Li
authors.affiliation: the Institute of Genomic Medicine, Wenzhou Medical University, 268 West Xueyuan Road, Wenzhou, Zhejiang Province 325000, China.
authors.forename: Qi
authors.initials: Q
authors.lastname: Liu
authors.affiliation: the Beijing Institutes of Life Science, Chinese Academy of Sciences, Beijing 100101, China.
authors.forename: Lin
authors.initials: L
authors.lastname: Chen
authors.affiliation: the Institute of Genomic Medicine, Wenzhou Medical University, 268 West Xueyuan Road, Wenzhou, Zhejiang Province 325000, China.
authors.forename: Lu
authors.initials: L
authors.lastname: Lv
authors.affiliation: the Institute of Genomic Medicine, Wenzhou Medical University, 268 West Xueyuan Road, Wenzhou, Zhejiang Province 325000, China.
authors.forename: Xin
authors.initials: X
authors.lastname: Wang
authors.affiliation: the Institute of Genomic Medicine, Wenzhou Medical University, 268 West Xueyuan Road, Wenzhou, Zhejiang Province 325000, China.
authors.forename: Jinyu
authors.initials: J
authors.lastname: Wu
authors.affiliation: From the Institute of Psychology, Chinese Academy of Sciences, Beijing 100101, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Dai
authors.affiliation: the Department of Obstetrics and Gynecology, General Hospital of Chinese People's Liberation Army, Beijing 100853, China.
authors.forename: Guan
authors.initials: G
authors.lastname: Wang
authors.affiliation: the Department of Obstetrics and Gynecology, General Hospital of Chinese People's Liberation Army, Beijing 100853, China.
authors.forename: Enfeng
authors.initials: E
authors.lastname: Zhao
authors.affiliation: the Institute of Genomic Medicine, Wenzhou Medical University, 268 West Xueyuan Road, Wenzhou, Zhejiang Province 325000, China, tangkaifu@hotmail.com.
authors.forename: Kai-Fu
authors.initials: KF
authors.lastname: Tang
authors.affiliation: the Institute of Genomic Medicine, Wenzhou Medical University, 268 West Xueyuan Road, Wenzhou, Zhejiang Province 325000, China, the Beijing Institutes of Life Science, Chinese Academy of Sciences, Beijing 100101, China, zhongshengsun@yeah.net.
authors.forename: Zhong Sheng
authors.initials: ZS
authors.lastname: Sun
mesh_terms: D000328:Adult; D000368:Aged; D000818:Animals; D001692:Biological Transport / Q000235:genetics; D063646:Carcinogenesis / Q000235:genetics; D045744:Cell Line, Tumor; D002471:Cell Transformation, Neoplastic / Q000235:genetics; D019175:DNA Methylation / Q000235:genetics; D004847:Epithelial Cells / Q000473:pathology; D005260:Female; D015972:Gene Expression Regulation, Neoplastic / Q000235:genetics; D020868:Gene Silencing; D005947:Glucose / Q000378:metabolism*; D006801:Humans; D019344:Lactic Acid / Q000096:biosynthesis; D051379:Mice; D008875:Middle Aged; D010051:Ovarian Neoplasms / Q000235:genetics* / Q000378:metabolism* / Q000473:pathology; D016283:Proto-Oncogene Proteins p21(ras) / Q000378:metabolism*; D018631:ras Proteins / Q000172:deficiency* / Q000235:genetics*
chemical_list: C084355:RRAD protein, human; D019344:Lactic Acid; C501009:HRAS protein, human; D016283:Proto-Oncogene Proteins p21(ras); D018631:ras Proteins; D005947:Glucose
keywords: DNA Methylation; Metabolism; Oncogenic Transformation; Ovarian Cancer; RRAD; Ras; Tumor Suppressor Gene