摘要
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, SW1116and 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 p161NK4A promoter in HT-29 cells was also determined by methylation-specific PGR (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 ceils before treatment. After treatment of 1μmol/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-mycgenes 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.
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 p16(INK4A),p21^(WAF1),APC and c-rnyc genes were observed by using RT-PCR.The methylation status of p16^(INK4A)promoter in HT-29 cells was also determined by methylation-specific PCR(MSP). RESULTS:Weak expressions of p16(INK4A)and APCin the three colon cancer cells were detected,and p21(WAF1)expression was not found in SW1116 and Colo-320 cells before treatment.After treatment of I μmol/L but not 10 μmol/L of 5-aza-dC,the methylation level of p16(INK4A)gene promoter decreased significantly,and the hypomethylation led to the up-regulation of p16^(INK4A)gene transcription in HT-29 cells. In the cell lines of SW1116 and Colo-320,p16(INK4A)and APC mRNA expressions were obviously enhanced after treatment of either 10 μmol/L or 5 μmol/1 5-aza-dC for 24 h.However, no evidence was found that methylation regulated the expression of p21^(WAF1)and c-mycgenes in human colon cancer cell lines. CONCLUSION:Expression of p16^(INK4A)and APC genes is regulated by DNA methylation in three human colon cancer cell lines.
基金
the National Natural Science Foundation of China, No.30170413
the Ministry of Education of China,No.199946
the Key Subject Funds of Shanghai Education Committee to Jing-Yuan Fang
