Hepatitis B virus X protein - Shanghai Medical College, Fudan University

StephenW

<http://www3.interscience.wiley.com/journal/122588451/abstract>

Journal of Viral Hepatitis
Volume 17 Issue 2, Pages 98 - 107
Published Online: 2 Sep 2009
© 2010 Blackwell Publishing Ltd

Hepatitis B virus X protein induces hypermethylation of p16INK4A promoter via
DNA methyltransferases in the early stage of HBV-associated
hepatocarcinogenesis

Y.-Z. Zhu 1 , R. Zhu 1 , J. Fan 2 , Q. Pan 2 , H. Li 1 , Q. Chen 1 and H.-G.
Zhu 1

  1 Department of Pathology, Shanghai Medical College, Fudan University,
Shanghai, China ; and  2 Liver Cancer Institute, Zhongshan Hospital, Fudan
University, Shanghai, China

Correspondence to Rong Zhu, PhD, Department of Pathology, Shanghai Medical
College, Fudan University, 138 Yixueyuan Road, Shanghai 200032, China. E-mail:
[email protected]

Copyright © 2010 Blackwell Publishing Ltd

ABSTRACT
Summary. The aim of the present study was to authenticate the involvement of
DNA methyltransferases (DNMTs) and methyl-CpG binding domain protein 2 (MBD2)
in the process of HBx induced p16INK4A promoter hypermethylation in
HBV-related hepatocellular carcinoma (HCC) and their corresponding
noncancerous liver tissues. Eighty-eight fresh tissue specimens of surgically
resected HBV-associated HCC and their corresponding noncancerous liver tissues
were studied. The methylation status of the p16INK4A promoter was determined
by methylation-specific polymerase chain reaction (MSP). Reverse transcription
and real-time polymerase chain reaction (RT-PCR) showed the expression of
DNMTs, MBD2 and HBx. Western blot and immunohistochemistry were used for the
protein analysis of HBx, DNMT1, DNMT3A and P16. Tissue HBV-DNA levels were
determined by RT-PCR. HBV genotype was examined by nested PCR and restriction
fragment length polymorphism (RFLP). In the corresponding noncancerous liver
tissues, higher HBx expression was associated with the hypermethylation of the
p16INK4A promoter. HBx was positively correlated with the DNMT1 and DNMT3A at
both the mRNA and protein level. Furthermore, HBx, DNMT1 and DNMT3A protein
expression were negatively correlated with p16 protein expression. In HCC
tissues, HBx was positively correlated with DNMT1 and DNMT3A at both mRNA and
protein level, but HBx expression did not correlate with hypermethylation of
the p16INK4A promoter or p16 protein expression. The methylation status of the
p16INK4A promoter did not correlate with clinicopathological characteristics.
DNMT1 and DNMT3A may play important roles in the process of HBx inducing
hypermethylation of the p16INK4A promoter in the early stages of
HBV-associated HCC. HBx-DNMTs-p16INK4A promoter hypermethylation may
constitute a mechanism for tumorigenesis during HBV-associated
hepatocarcinogenesis.

-------------------------------------------------------------------------------
-
Received February 2009; accepted for publication May 2009
DIGITAL OBJECT IDENTIFIER (DOI)
10.1111/j.1365-2893.2009.01156