Hepatitis B virus X protein downregulates expression of the miR-16 family in malignant hepatocytes in vitro.

Abstract

BACKGROUND:

Hepatitis B virus X protein (HBx) is involved in the initiation and progression of hepatocellular carcinoma (HCC) by regulating the host protein-coding genes. In this study, we showed that HBx altered the expression of microRNAs (miRNAs) to promote proliferation and transformation in malignant hepatocytes in vitro.

METHODS:

miRNA microarray and quantitative reverse-transcription polymerase chain reactions (qRT-PCRs) were performed to identify miRNAs that were differentially regulated by HBx in HCC cells. Protein, mRNA, and miRNA expression analyses; cell cycle and apoptosis analyses; loss/gain-of-function analysis; and luciferase reporter assays were performed to delineate the consequences of miR-16 family repression in HepG2 cells.

RESULTS:

Hepatitis B virus X protein induced widespread deregulation of miRNAs in HepG2 cells, and the downregulation of the miR-16 family was reproducible in HepG2, SK-HEP-1, and Huh7 cells. CCND1, a target of the miR-16 family, was derepressed by HBx in HepG2 cells. c-Myc mediated the HBx-induced repression of miR-15a/16 in HepG2 cells. Ectopically expressed miR-15a/16 suppressed the proliferation, clonogenicity, and anchorage-independent growth of HBx-expressing HepG2 cells by arresting them in the G1 phase and inducing apoptosis, whereas reduced expression of miR-16 accelerated the growth and cell-cycle progression of HepG2 cells.

CONCLUSIONS:

Hepatitis B virus X protein altered the in vitro expression of miRNAs in host malignant hepatocytes, particularly downregulating the miR-16 family. Repression of miR-15a/16 is c-Myc mediated and is required for the HBx-induced transformation of HepG2 cells in vitro. Therefore, miR-16 family may serve as a therapeutic target for hepatitis B virus (HBV)-associated HCC.

• Authors: G Wu, F Yu, Z Xiao, K Xu, J Xu, W Tang, J Wang, E Song
• Journal: British journal of cancer (Br J Cancer) Vol. 105 Issue 1 Pg. 146-53 (Jun 28 2011) ISSN: 1532-1827 [Electronic] England
• PMID: 21629246 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• MIRN16 microRNA, human
• MicroRNAs
• RNA, Messenger
• Trans-Activators
• Viral Regulatory and Accessory Proteins
• hepatitis B virus X protein
• Luciferases

Topics

• Apoptosis
• Blotting, Western
• Carcinoma, Hepatocellular (genetics, metabolism)
• Cell Cycle
• Cell Proliferation
• Cells, Cultured
• Down-Regulation
• Hepatocytes (metabolism, pathology)
• Humans
• In Vitro Techniques
• Liver Neoplasms (genetics, metabolism)
• Luciferases (metabolism)
• MicroRNAs (genetics, metabolism)
• RNA, Messenger (genetics)
• Reverse Transcriptase Polymerase Chain Reaction
• Trans-Activators (genetics, metabolism)
• Viral Regulatory and Accessory Proteins