The Hypermethylation Of MGMT Gene In Promotor Region And The Genesis And Progress Of Colorectal Cancer

[Objective] To explored the effect of hypermethylation of multiple site of CpG islands in the promoter regions of O6-methylguanine-DNA methyltransferase MGMT genes on colorectal tumorigenesis and progression. To detected the expression of MGMT protein correlation with the expression of p53 in colorectal carcinomas.[Methods] Use a methylation-specific oligonucleotide microarray for quantitative analysis in 20 colorectal carcinomas and tissues adjacent to the tumor for hypermethylation detection in MGMT gene promoter. The expression of MGMT protein and p53 protein were studied in the same samples using immunohistochemistry.[Results] Among the 20 pair samples, MGMT gene hypermethylation was detected in 17 cases(85%).The level of hypermethylation in promoter MGMT in colorectal carcinomas is higher than in tissues adjacent (P<0.05). And furthermore, the hypermethylation level of 13-15 loci CpG island was much higher than the other three. There is no statistical significant difference MGMT hypermethylation from colorectal carcinomas of histological grade (P>0.05) or lymph node metastasis (P>0.05). Loss of MGMT protein expression was found in 70% (14/ 20) of carcinomas and 30 % (6/ 20) of tissues adjacent respectively. There were significant difference among them ( P<0.05). The expression of p53 protein was found in 70% (14/ 20) of carcinomas and 5 % (1/ 20) of tissues adjacent respectively. The expression of MGMT was negatively correlated with the expression of p53.( P< 0. 01) .[Conclusions] Promoter hypermethylation of MGMT gene were common...