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

Figure 2 N-nitroso compound treatment induces gastric epithelial cell malignant transformation. A: Cell proliferation monitored by cell counting in N-methyl-N’-nitro-N-nitrosoguanidine (MNNG)/N-methyl-N-nitroso-urea (MNU)-treated and control cells; B and C: Cell anchorage-independent growth on soft agar and cell colony formation. Top, representative images; bottom, quantitative results of cell colony per field; D: Wound healing assay. Top, representative images of wound healing assay; right, relative percentage of wound closure after treatment; E and F: Tumor growth curve and tumor weight in nude mice injected subcutaneously with the transformed cells induced by MNNG/MNU and control cells. The analyses were repeated three times, and the results are expressed as the mean ± SD. ^aP < 0.05; ^bP < 0.01.