HBx represses RIZ1 expression by DNA methyltransferase 1 involvement in decreased miR-152 in hepatocellular carcinoma.
Hepatitis B virus (HBV) is mainly suspected to promote hepatocellular carcinoma (HCC) development by epigenetic alteration. The HBV X protein (HBx) plays a key role in the molecular pathogenesis of HBV-related HCC. However, the mechanism of HBx-mediated hepatocarcinogenesis remains to be elucidated. RIZ1 gene, a candidate HCC suppressor gene, is frequently found to be hypermethylated and downregulated in HCC. In the present study, we show that the expression of RIZ1 was downregulated in 65% HCC tissues. Decreased expression of RIZ1 was restored by 5'-Aza in MHCC-97H HCC cell lines. HBx recombinant transfection increased DNMT1 expression level and suppressed RIZ1 expression. Moreover, knockdown of DNMT1 by siRNA restored RIZ1 expression in HCC cell SMMC-7721 and reduced methylated CpG sites of RIZ1. ChIP results showed that DNMT1 protein could bind to RIZ1 promoter, and this interaction was further enhanced with the transfected HBX recombinant. Moreover, miR-152 was decreased and involved in upregulation of DNMT1 in HBx transfected cells, at least partly, contributed to the epigenetic inactivation of RIZ1. Taken together, our data found that HBx repressed RIZ1 expression via DNMT1, which offered a new mechanism of RIZ1 inactivation in HCC, except for the widely known DNA methylation. These results enriched the epigenetic mechanism by which HBx contributes to pathogenesis of HBV-HCC.
Department of Medical Genetics and Developmental Biology, Medical School of Southeast University and The Key Laboratory of Developmental Genes and Human Diseases, Ministry of Education, Southeast University, Nanjing, Jiangsu, P.R. China.
Zhujiang
Z
Zhao
Department of Medical Genetics and Developmental Biology, Medical School of Southeast University and The Key Laboratory of Developmental Genes and Human Diseases, Ministry of Education, Southeast University, Nanjing, Jiangsu, P.R. China.
Ying
Y
Hu
Department of Medical Genetics and Developmental Biology, Medical School of Southeast University and The Key Laboratory of Developmental Genes and Human Diseases, Ministry of Education, Southeast University, Nanjing, Jiangsu, P.R. China.
Xiaohui
X
Shen
Department of Medical Genetics and Developmental Biology, Medical School of Southeast University and The Key Laboratory of Developmental Genes and Human Diseases, Ministry of Education, Southeast University, Nanjing, Jiangsu, P.R. China.
Yingbin
Y
Lao
Department of Pathology, Southeast University, Zhongda Hospital, Nanjing, Jiangsu, P.R. China.
Lihua
L
Zhang
Department of Medical Genetics and Developmental Biology, Medical School of Southeast University and The Key Laboratory of Developmental Genes and Human Diseases, Ministry of Education, Southeast University, Nanjing, Jiangsu, P.R. China.
Xuemei
X
Qiu
Department of Medical Genetics and Developmental Biology, Medical School of Southeast University and The Key Laboratory of Developmental Genes and Human Diseases, Ministry of Education, Southeast University, Nanjing, Jiangsu, P.R. China.
Jiaojiao
J
Hu
Department of Medical Genetics and Developmental Biology, Medical School of Southeast University and The Key Laboratory of Developmental Genes and Human Diseases, Ministry of Education, Southeast University, Nanjing, Jiangsu, P.R. China.
Pihai
P
Gong
The First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu, P.R. China.
He
H
Cui
The First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu, P.R. China.
Sen
S
Lu
Department of Medical Genetics and Developmental Biology, Medical School of Southeast University and The Key Laboratory of Developmental Genes and Human Diseases, Ministry of Education, Southeast University, Nanjing, Jiangsu, P.R. China.
Ying
Y
Zheng
Department of Medical Genetics and Developmental Biology, Medical School of Southeast University and The Key Laboratory of Developmental Genes and Human Diseases, Ministry of Education, Southeast University, Nanjing, Jiangsu, P.R. China.
Menghan
M
Zhou
Department of Medical Genetics and Developmental Biology, Medical School of Southeast University and The Key Laboratory of Developmental Genes and Human Diseases, Ministry of Education, Southeast University, Nanjing, Jiangsu, P.R. China.
Hong
H
Fan
D006528:Carcinoma, Hepatocellular / Q000235:genetics / Q000378:metabolism / Q000821:virology*; D045744:Cell Line, Tumor; D000076123:DNA (Cytosine-5-)-Methyltransferase 1; D004248:DNA (Cytosine-5-)-Methyltransferases / Q000235:genetics / Q000378:metabolism*; D019175:DNA Methylation; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D015536:Down-Regulation; D044127:Epigenesis, Genetic; D055785:Gene Knockdown Techniques; D056945:Hep G2 Cells; D006515:Hepatitis B virus / Q000235:genetics / Q000378:metabolism; D011495:Histone-Lysine N-Methyltransferase / Q000235:genetics* / Q000378:metabolism; D006801:Humans; D008113:Liver Neoplasms / Q000235:genetics / Q000378:metabolism / Q000821:virology*; D035683:MicroRNAs / Q000235:genetics*; D009687:Nuclear Proteins / Q000235:genetics* / Q000378:metabolism; D011994:Recombinant Proteins / Q000378:metabolism; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism*; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism; D054334:Viral Regulatory and Accessory Proteins
D004268:DNA-Binding Proteins; C550856:MIRN152 microRNA, human; D035683:MicroRNAs; D009687:Nuclear Proteins; D011994:Recombinant Proteins; D015534:Trans-Activators; D014157:Transcription Factors; D054334:Viral Regulatory and Accessory Proteins; C057628:hepatitis B virus X protein; D000076123:DNA (Cytosine-5-)-Methyltransferase 1; D004248:DNA (Cytosine-5-)-Methyltransferases; C000619380:DNMT1 protein, human; D011495:Histone-Lysine N-Methyltransferase; C093563:PRDM2 protein, human