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

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.

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.

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.

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.