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

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.

Differences in oral habit and lymphocyte subpopulation affect malignant transformation of patients with oral precancer.

BACKGROUND/PURPOSE: In Taiwan, the combination of betel quid chewing, alcohol consumption, and smoking habits increases oral cancer risk by 123-fold compared to persons without these habits. Lymphocyte populations in patients may potentially affect the malignant transformation of oral precancer. METHODS: A total of 28 patients with oral precancer from our previous cohort were enrolled in this study, and their personal information and oral habits were documented. Their lymphocyte populations (CD4+, CD8+, CD19+, and CD56+) and activation markers (CD25 and CD69) were determined by flow cytometry from 1999 to 2004. After follow up till December 2014, data of patients with/without malignant transformation were recorded, and the relation between oral habits and percentage of initial lymphocyte markers was evaluated using the Student t test and Fisher's exact test. RESULTS: Ten precancer patients developed oral squamous cell carcinoma with a mean period of malignant transformation of 6.8 ± 2.1 years. Patients with malignant transformation had a mean age of 48.4 ± 5.0 years (n = 10), relatively more than that of patients without malignant transformation (41.6 ± 6.3 years, n = 18) (p < 0.05). An increase was noted in the population of peripheral blood mononuclear cells expressing CD4+CD69+, CD19+CD69+, and CD56+CD69+ (p < 0.05) in precancer patients with malignant transformation. Alcohol consumption showed an association with the malignant transformation of patients with precancer (p = 0.030), whereas betel quid and smoking showed little effect. CONCLUSION: These results suggest that age, alcohol consumption, and early activation of T cells, B cells, and natural killer cells are crucial in the malignant transformation of oral precancer. Analysis of patient's lymphocyte populations may help predict the malignant transformation of oral precancer.