title: MicroRNA-101, down-regulated in hepatocellular carcinoma, promotes apoptosis and suppresses tumorigenicity.
abstract: Although aberrant microRNA (miRNA) expressions have been observed in different types of cancer, their pathophysiologic role and their relevance to tumorigenesis are still largely unknown. In this study, we first evaluated the expression of 308 miRNAs in human hepatocellular carcinoma (HCC) and normal hepatic tissues and identified 29 differentially expressed miRNAs in HCC tissues. miR-101, a significantly down-regulated miRNA, was further studied in greater detail because the signal pathway(s) regulated by miR-101 and the role of miR-101 in tumorigenesis have not yet been elucidated. Interestingly, decreased expression of miR-101 was found in all six hepatoma cell lines examined and in as high as 94.1% of HCC tissues, compared with their nontumor counterparts. Furthermore, ectopic expression of miR-101 dramatically suppressed the ability of hepatoma cells to form colonies in vitro and to develop tumors in nude mice. We also found that miR-101 could sensitize hepatoma cell lines to both serum starvation- and chemotherapeutic drug-induced apoptosis. Further investigation revealed that miR-101 significantly repressed the expression of luciferase carrying the 3'-untranslated region of Mcl-1 and reduced the endogenous protein level of Mcl-1, whereas the miR-101 inhibitor obviously up-regulated Mcl-1 expression and inhibited cell apoptosis. Moreover, silencing of Mcl-1 phenocopied the effect of miR-101 and forced expression of Mcl-1 could reverse the proapoptotic effect of miR-101. These results indicate that miR-101 may exert its proapoptotic function via targeting Mcl-1. Taken together, our data suggest an important role of miR-101 in the molecular etiology of cancer and implicate the potential application of miR-101 in cancer therapy.
authors.affiliation: Key Laboratory of Gene Engineering of the Ministry of Education, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, PR China.
authors.forename: Hang
authors.initials: H
authors.lastname: Su
authors.forename: Jian-Rong
authors.initials: JR
authors.lastname: Yang
authors.forename: Teng
authors.initials: T
authors.lastname: Xu
authors.forename: Jun
authors.initials: J
authors.lastname: Huang
authors.forename: Li
authors.initials: L
authors.lastname: Xu
authors.forename: Yunfei
authors.initials: Y
authors.lastname: Yuan
authors.forename: Shi-Mei
authors.initials: SM
authors.lastname: Zhuang
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000235:genetics*; D006528:Carcinoma, Hepatocellular / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D045744:Cell Line, Tumor; D002471:Cell Transformation, Neoplastic / Q000235:genetics / Q000378:metabolism; D015536:Down-Regulation; D006367:HeLa Cells; D006801:Humans; D008113:Liver Neoplasms / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D051379:Mice; D008819:Mice, Nude; D035683:MicroRNAs / Q000096:biosynthesis* / Q000235:genetics; D064549:Myeloid Cell Leukemia Sequence 1 Protein; D041681:NIH 3T3 Cells; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000235:genetics; D014162:Transfection
chemical_list: C534072:MIRN101 microRNA, human; C581233:MIRN101 microRNA, mouse; C579094:Mcl1 protein, mouse; D035683:MicroRNAs; D064549:Myeloid Cell Leukemia Sequence 1 Protein; D019253:Proto-Oncogene Proteins c-bcl-2