Colorectal Cancer
Copyright ©The Author(s) 2003. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Gastroenterol. Sep 15, 2003; 9(9): 1976-1980
Published online Sep 15, 2003. doi: 10.3748/wjg.v9.i9.1976
Effects of DNA methylation on expression of tumor suppressor genes and proto-oncogene in human colon cancer cell lines
Jing-Yuan Fang, Juan Lu, Ying-Xuan Chen, Li Yang
Jing-Yuan Fang, Juan Lu, Ying-Xuan Chen, Li Yang, Shanghai Institute of Digestive Diseases, Renji Hospital, Shanghai Second Medical University, Shanghai 200001, China
Author contributions: All authors contributed equally to the work.
Supported by the National Natural Science Foundation of China, No. 30170413, and PhD Funds from the Ministry of Education of China, No. 199946, and the Key Subject Funds of Shanghai Education Committee to Jing-Yuan Fang
Correspondence to: Dr. Jing-Yuan Fang, Shanghai Institute of Digestive Diseases, 145 Shandong Zhong Road, Shanghai 200001, China. jingyuanfang@yahoo.com
Telephone: +86-21-63200874 Fax: +86-21-63266027
Received: December 22, 2002
Revised: January 5, 2003
Accepted: January 14, 2003
Published online: September 15, 2003
Abstract

AIM: To investigate the effects of DNA methylation on the expression of tumor suppressor genes and proto-oncogene in human colon cancer cell lines.

METHODS: Three colon cancer cell lines (HT-29, SW1116 and Colo-320) treated with different concentrations of DNA methyltransferase inhibitor, 5-aza-2’-deoxycytidine (5-aza-dC) were used to induce DNA demethylation. The expressions of p16INK4A, p21WAF1, APC and c-myc genes were observed by using RT-PCR. The methylation status of p16INK4A promoter in HT-29 cells was also determined by methylation-specific PCR (MSP).

RESULTS: Weak expressions of p16INK4A and APC in the three colon cancer cells were detected, and p21WAF1 expression was not found in SW1116 and Colo-320 cells before treatment. After treatment of 1 μmol/L but not 10 μmol/L of 5-aza-dC, the methylation level of p16INK4A gene promoter decreased significantly, and the hypomethylation led to the up-regulation of p16INK4A gene transcription in HT-29 cells. In the cell lines of SW1116 and Colo-320, p16INK4A and APC mRNA expressions were obviously enhanced after treatment of either 10 μmol/L or 5 μmol/L 5-aza-dC for 24 h. However, no evidence was found that methylation regulated the expression of p21WAF1 and c-myc genes in human colon cancer cell lines.

CONCLUSION: Expression of p16INK4A and APC genes is regulated by DNA methylation in three human colon cancer cell lines.

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