Liver Cancer
Copyright ©2007 Baishideng Publishing Group Co., Limited. All rights reserved.
World J Gastroenterol. May 28, 2007; 13(20): 2791-2797
Published online May 28, 2007. doi: 10.3748/wjg.v13.i20.2791
Alteration of nuclear matrix-intermediate filament system and differential expression of nuclear matrix proteins during human hepatocarcinoma cell differentiation
Jian Tang, Jing-Wen Niu, Dong-Hui Xu, Zhi-Xing Li, Qi-Fu Li, Jin-An Chen
Jian Tang, Jing-Wen Niu, Zhi-Xing Li, Qi-Fu Li, Jin-An Chen, The Key Laboratory of Chinese Ministry of Education for Cell Biology and Tumor Cell Engineering, School of Life Sciences, Xiamen University, Xiamen 361005, Fujian Province, China
Dong-Hui Xu, Department of Hepatic Biliary Pancreatic Vascular Surgery, 1st Hospitalof Xiamen, Fujian Medical University, Xiamen 361003, Fujian Province, China
Author contributions: All authors contributed equally to the work.
Supported by the National Natural Science Foundation of China, No. 30470877
Correspondence to: Dr Qi-Fu Li, Laboratory of Cell Biology, School of Life Sciences,Xiamen University, Xiamen 361005, Fujian Province, China. chifulee@xmu.edu.cn
Telephone: +86-592-2185363 Fax: +86-592-2181015
Received: January 24, 2007
Revised: February 10, 2007
Accepted: February 24, 2007
Published online: May 28, 2007
Abstract

AIM: To investigate the association between the configurational and compositional changes of nuclear matrix and the differentiation of carcinoma cells.

METHODS: Cells cultured with or without 5 × 10-3 mmol/L of hexamethylene bisacetamide (HMBA) on Nickel grids were treated by selective extraction and prepared for whole mount observation under electron microscopy. The samples were examined under transmission electron microscope. Nuclear matrix proteins were selectively extracted and subjected to subcellular proteomics study. The protein expression patterns were analyzed by PDQuest software. Spots of differentially expressed nuclear matrix proteins were excised and subjected to in situ digestion with trypsin. The peptides were analyzed by matrix-assisted laser-desorption/ionization time of flight mass spectrometry (MALDI-TOF-MS). Data were submitted for database searching using Mascot tool (www.matrixscience.com).

RESULTS: The nuclear matrix (NM) and intermediate filament (IF) in SMMC-7721 hepatocarcinoma cells were found relatively sparse and arranged irregularly. The nuclear lamina was non-uniform, and two kinds of filaments were not tightly connected. After induction for differentiation by HMBA, the NM-IF filaments were concentrated and distributed uniformly. The heterogeneous population of filaments, including highly branched utrathin filaments could also be seen in the regular meshwork. The connection between the two kinds of filaments and the relatively thin, condensed and sharply demarcated lamina composed of intermediate-sized filaments was relatively fastened. Meanwhile, 21 NM proteins changed remarkably during SMMC-7721 cell differentiation. Four proteins, i.e. mutant Pyst1, hypothetical protein, nucleophosmin1, and LBP were downregulated, whereas four other proteins, eIF6, p44 subunit, β-tubulin, and SIN3B were upregulated with the last one, SR2/ASF found only in the differentiated SMMC-7721 cells.

CONCLUSION: The induced differentiation of SMMC-7721 cells by HMBA is accompanied by the configurational changes of nuclear matrix-intermediate filament (NM-IF) system and the compositional changes of nuclear matrix protein expression. These changes may be important morphological or functional indications of the cancer cell reversion.

Keywords: Nuclear matix-intermediate filament system; Nuclear matrix protein; Hexamethylamine bisacetamide; SMMC-7721 cells; Cell differentiation