DNA fragmentation induced by cigarette smoke in oral cancer cells.

BACKGROUND/AIM Cigarette smoke (CS) is the main inducer of oral cancer, increasing the prevalence by 4-7 times. We examined induction of apoptosis by CS exposure of SCC-25 and SCC-15 oral cancer cells. MATERIALS AND METHODS After controlled exposure to CS of various durations and at different time points we measured DNA fragmentation to assay apoptotic levels. RESULTS SCC-15 cells showed a 70% (p<0.05) increase in apoptotic levels immediately after 30 min of exposure to CS. Twenty-four hours after 30-min CS exposure a further increase in apoptotic levels to 178% (p<0.05) could be observed. However, SCC-15 cells showed a decrease in apoptotic levels immediately after 180-min exposure to CS. CS-exposed SCC-25 cells did not show such CS-related effects. CONCLUSION SCC-15 and SCC-25 oral cancer cells respond differently to CS regarding apoptotic cell death levels. In this respect, SCC-15 cells are sensitive to CS, while SCC-25 cells are not. Further comparisons between these cells may give insight regarding relationships between CS, apoptosis and invasiveness of oral cancer.