Cigarette smoke-induced effects on the cell cycle in oral cancer cells: reduction of G2/M fraction.

BACKGROUND: Cigarette smoke (CS) is the main inducer of oral cancer, increasing its prevalence by 4-7 times. MATERIALS AND METHODS: We examined the suitability of cell models SCC-25 and SCC-15 for studying effects of CS on oral cancer cells and whether CS significantly affects the cell cycle using fluorescence-activated cell sorting assays. RESULTS: There was significant change in the fraction of SCC-15 cells in pre-G1 state following CS exposure. At 60 and 90 min, increase in the pre-G1 cell fraction was 118% (p<0.05) and 135% (p<0.01) respectively. The G2/M cell fraction was significantly lower following CS exposure. At 90 and 120 min following CS exposure, the G2/M fraction levels had declined by 44% (p<0.05) and 34% (p<0.01) respectively. Results for SCC-25 cells were similar. At 90 and 120 min following CS exposure, the pre-G1 fraction of the cells increased by 230% and 550%, respectively (p<0.01). At 120 min of CS exposure, the fraction of G2/M cells was lower by 47% (p<0.05) compared to controls. CONCLUSION: CS profoundly affects the cell-cycle distribution in both SCC-15 and SCC-25 oral cancer cellular models. Such effects have been associated with DNA damage and carcinogenesis. Both models are useful for studying oral cancer pathogenesis.