O6-methylguanine DNA methyltransferase is upregulated in malignant transformation of gastric epithelial cells via its gene promoter DNA hypomethylation

Figure 5 Inhibition of O⁶-methylguanine-DNA methyltransferase contributes to the N-nitroso compound-induced cell malignant phenotype. A and B: Cell anchorage-independent growth on soft agar and cell colony formation of N-methyl-N’-nitro-N-nitrosoguanidine/N-methyl-N-nitroso-urea-induced cells after O⁶-BG treatment; C: Cell anchorage-independent growth on soft agar of cells with O⁶-methylguanine-DNA methyltransferase (MGMT) knock-down; D: Knock-down efficiency of MGMT detected by Western blot; E and F: Cell anchorage-independent growth on soft agar and cell colony formation of MGMT overexpressing cells; G: The mRNA expression of MGMT in gastric endoscopic biopsy samples. The analyses were repeated three times, and the results are expressed as the mean ± SD. ^a,cP < 0.05. ^cP < 0.05, precancerous lesion and early cancer vs advanced cancer. EV: Empty vector; MGMT: MGMT overexpression; MGMT: O⁶-methylguanine-DNA methyltransferase.