Liver Cancer
Copyright ©2005 Baishideng Publishing Group Inc. All rights reserved.
World J Gastroenterol. Apr 7, 2005; 11(13): 1903-1909
Published online Apr 7, 2005. doi: 10.3748/wjg.v11.i13.1903
Inhibitory effect of tumor suppressor p33ING1b and its synergy with p53 gene in hepatocellular carcinoma
Zhi Zhu, Jing Lin, Jian-Hui Qu, Mark A. Feitelson, Can-Rong Ni, Fang-Mei Li, Ming-Hua Zhu
Zhi Zhu, Jing Lin, Jian-Hui Qu, Can-Rong Ni, Fang-Mei Li, Ming-Hua Zhu, Department of Pathology, Changhai Hospital, Second Military Medical University, Shanghai 200433, China
Mark A. Feitelson, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA, USA
Author contributions: All authors contributed equally to the work.
Correspondence to: Ming-Hua Zhu, Department of Pathology, Changhai Hospital, Second Military Medical University, 174 Changhai Road, Shanghai 200433, China. mhzhu2000@hotmail.com
Telephone: +86-21-25074604 Fax: +86-21-25074604
Received: July 20, 2004
Revised: July 21, 2004
Accepted: September 4, 2004
Published online: April 7, 2005
Abstract

AIM: To investigate the inhibitory effect of tumor suppressor p33ING1b and its synergy with p53 gene in hepatocellular carcinoma (HCC).

METHODS: Recombinant sense and antisense p33ING1b plasmids were transfected into hepatoma cell line HepG2 with lipofectamine. Apoptosis, G0/G1 arrest, cell growth rate and cloning efficiency in soft agar of HepG2 were analyzed after transfection. In three hepatoma cell lines with different endogenous p53 gene expressions, the synergistic effect of p33ING1b with p53 was analyzed by flow cytometry and luciferase assay was performed to detect the activation of p53 downstream gene p21WAF1/CIP1. In addition, the expression and mutation rates of p33ING1b in HCC tissues were measured by immunohistochemistry and polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP).

RESULTS: Overexpression of p33ING1b inhibited cell growth of HepG2, induced more apoptosis and protected cells from growth in soft agar. Combined transfer of p33ING1b and p53 gene promoted hepatoma cell apoptosis, G0/G1 arrest and elevated expression of p21WAF1/CIP1. Immunostaining results showed co-localized p33ING1b with P53 protein in HCC tissues and there was a significant relation between protein expression rates of these two genes (P<0.01). Among 28 HCC samples, p33ING1b presented a low gene mutation rate (7.1%).

CONCLUSION: p33ING1b collaborates with p53 in cell growth inhibition, cell cycle arrest and apoptosis in HCC. Loss or inactivation of p33ING1b normal function may be an important mechanism for the development of HCC retaining wild-type p53.

Keywords: Gene p33ING1b; Gene p53; Apoptosis; Cell cycle arrest; Gene p21waf1; Liver neoplasm