EFFECTS OF SMOKELESS TOBACCO ON CHEMICALLY TRANSFORMED HAMSTER ORAL KERATINOCYTES - ROLE OF ANGIOTENSIN I-CONVERTING ENZYME

The purpose of this study was to determine whether exposure of chemica lly transformed golden Syrian hamster oral epidermoid carcinoma cell ( HCPC-1) cultures to smokeless tobacco extract (STE) is associated with a decrease in specific angiotensin I-converting enzyme (ACE) activity and whether this decrease potentiates bradykinin-induced cell growth. We found that STE induced a significant concentration- and time-depen dent decrease in ACE activity in cultured HCPC-1 cells (P < 0.05). STE alone had no significant effect on cell number. Bradykinin alone indu ced a slight, but significant, increase in cell number (P < 0.05). The se effects were significantly potentiated by STE (P < 0.01). We conclu de that STE potentiates bradykinin-induced HCPC-1 cell growth, in part by attenuating specific ACE activity in these cells.