Cytotoxicity and transformation of C3H10T1/2 cells induced by areca nut components.

ABSTRACT

BACKGROUND/PURPOSE: Betel quid (BQ) chewing is popular in Taiwan and many other countries. There are about 200-600 million BQ chewers in the world. BQ chewing is one major risk factor of oral cancer and oral submucous fibrosis (OSF). While areca nut (AN), a main component of BQ, exhibits genotoxicity, its transformation capacity and its role in the initiation and promotion stages of carcinogenesis are not fully clear. METHODS: Mouse C3H10T1/2 cells were exposed to AN extract (ANE) for 24 hours. Cytotoxicity was evaluated by colony forming efficiency. For the transformation assay, C3H10T1/2 cells were exposed to ANE for 24 hours and then incubated in medium with/without 12-O-tetradecanolylphorbol-13-acetate (TPA; a tumor promoter) for 42 days. Cells were stained with Giemsa and type II and type III transformed foci were counted for analysis of the transformation capacity of ANE. RESULTS: ANE exhibited cytotoxicity to C3H10T/12 cells at concentrations higher than 320 µg/mL as shown by a decrease in colony numbers. ANE (80-640 µg/mL) alone mildly stimulated the transformed foci formation (p > 0.05). In the presence of TPA, ANE (80-640 µg/mL) markedly stimulated the transformed foci formation. The percentage of dishes with foci increased from 0% in controls to 20% in ANE (80 µg/mL and 320 µg/mL)-treated groups and further increased to 65-94% in ANE plus TPA groups. CONCLUSION: These results indicate that ANE is a weak complete carcinogen. ANE is an effective tumor initiator and can induce malignant transformation of C3H10T1/2 cells in the presence of a tumor promoter. ANE may be involved in multistep chemical carcinogenesis by its malignant transformation capacity.