Methylation pattern of the MGMT and MLH1 genes in SCC-9, SCC-15, and SCC-25 cells. A. MS-HRM analysis showed MGMT gene is partially (50%) methylated in SCC-9 cells. The effect of 5-Aza-2CdR at 0.1 μM, 0.3 and 1 μM after 72 h of treatment promoted significant demethylation (25%) of the MGMT gene in SCC-9 (P<0.05). However, no effect of 5-Aza-2CdR at 3 μM concentration. No effect of cisplatin (0.1 and 4.44 μM) and combined groups with cisplatin 0.1 μM in methylation profile. No effect in methylation pattern also in the association of cisplatin at 4.44 μM with the 5-Aza-2CdR groups. MLH1 gene was demethylated in SCC-9. B, C. Both genes (MGMT and MLH1) were originally demethylated in SCC-15 and SCC-25 cells.