title: miR-338-3p is down-regulated by hepatitis B virus X and inhibits cell proliferation by targeting the 3'-UTR region of CyclinD1.
abstract: Hepatitis B virus X protein (HBx) is recognized as an oncogene in hepatocellular carcinoma (HCC). HBx regulates microRNA expression, including down-regulating miR-338-3p in LO2 cells. Here, we investigated miR-338-3p function in HBx-mediated hepatocarcinogenesis. In 23 HBV-infected HCC clinical patient tumor and adjacent non-tumor control tissues, 17 and 19 tumors expressed HBx mRNA and protein, respectively. When considered as a group, HBV-infected HCC tumors had lower miR-338-3p expression than controls; however, miR-338-3p was only significantly down-regulated in HBx-positive tumors, indicating that HBx inversely correlated with miR-338-3p. Functional characterization of miR-338-3p indicated that miR-338-3p mimics inhibited cell proliferation by inducing cell cycle arrest at the G1/S phase as assessed by EdU and cell cycle assays in HBx-expressing LO2 cells. CyclinD1, containing two putative miR-338-3p targets, was confirmed as a direct target using 3'-UTR luciferase reporter assays from cells transfected with mutated binding sites. Mutating the 2397-2403 nt binding site conferred the greatest resistance to miR-338-3p suppression of CyclinD1, indicating that miR-338-3p suppresses CyclinD1 at this site. Overall, this study demonstrates that miR-338-3p inhibits proliferation by regulating CyclinD1, and HBx down-regulates miR-338-3p in HCC. This newly identified miR-338-3p/CyclinD1 interaction provides novel insights into HBx-mediated hepatocarcinogenesis and may facilitate therapeutic development against HCC.
authors.affiliation: Department of Infectious Disease, Xiangya Hospital, Central South University, Changsha, Hunan 410008, China.
authors.forename: Xiaoyu
authors.initials: X
authors.lastname: Fu
authors.affiliation: Department of Infectious Disease, Xiangya Hospital, Central South University, Changsha, Hunan 410008, China.
authors.forename: Deming
authors.initials: D
authors.lastname: Tan
authors.affiliation: Department of Infectious Disease, Xiangya Hospital, Central South University, Changsha, Hunan 410008, China.
authors.forename: Zhouhua
authors.initials: Z
authors.lastname: Hou
authors.affiliation: The Second Hospital of Nanjing, Nanjing, Jiangsu, 210000, China.
authors.forename: Zhiliang
authors.initials: Z
authors.lastname: Hu
authors.affiliation: Department of Infectious Disease, Xiangya Hospital, Central South University, Changsha, Hunan 410008, China.
authors.forename: Guozhen
authors.initials: G
authors.lastname: Liu
mesh_terms: D001483:Base Sequence; D001665:Binding Sites; D006528:Carcinoma, Hepatocellular / Q000235:genetics* / Q000378:metabolism / Q000821:virology; D002460:Cell Line; D049109:Cell Proliferation; D019938:Cyclin D1 / Q000235:genetics* / Q000378:metabolism; D015536:Down-Regulation; D019694:Hepatitis B, Chronic / Q000150:complications / Q000235:genetics / Q000378:metabolism; D054884:Host-Pathogen Interactions; D006801:Humans; D008113:Liver Neoplasms / Q000235:genetics* / Q000378:metabolism / Q000821:virology; D035683:MicroRNAs / Q000235:genetics* / Q000378:metabolism; D034622:RNA Interference; D015534:Trans-Activators / Q000502:physiology*; D054334:Viral Regulatory and Accessory Proteins
chemical_list: C530104:CCND1 protein, human; C532050:MIRN338 microRNA, human; D035683:MicroRNAs; D015534:Trans-Activators; D054334:Viral Regulatory and Accessory Proteins; C057628:hepatitis B virus X protein; D019938:Cyclin D1