Selective cytotoxicity of PEITC against oral cancer cells

Background: Current therapies for oral cancer are effective; however, the side effects such as loss of structure, severe mucositis and dry mouth could lead to poor quality of life. Therefore, new therapy selectively suppressing oral cancer with minimal side effect to normal tissue is urgently needed. Promisingly, 2-Phenethyl isothiocyanate (PEITC), a natural compound from cruciferous vegetables, was found to have selective cytotoxicity against cancer with high oxidative stress such as ovarian cancer and leukemia. While oral cancer also exhibits increased oxidative stress, the therapeutic potential of PEITC against oral cancer has not been evaluated. Objective: To investigate the cytotoxic effect of PEITC in oral cancer cells compared with that of immortalized non-tumorigenic keratinocytes. Methods: Six oral squamous cell carcinoma cell lines and two immortalized keratinocyte line were exposed to various concentrations of PEITC. Cytotoxicity of PEITC was evaluated using MTT and PI assay. The concentrations required to inhibit 50% cell survival (IC50) and percentage of cell death were then calculated, respectively.

Result: MTT assay showed that the average IC50 of PEITC against 6 oral cancer lines was 6.8 ± 1.4 µM, whereas IC50 for the immortalized keratinocytes was 21.4 ± 1.3 µM. Consistently, PI assay showed that 7 μM PEITC can kill more than 70% of oral cancer cells, while more than 80% of immortalized keratinocyte were alive.

Conclusion: This study showed that PEITC was more toxic to oral cancer cells than non-tumorigenic keratinocytes. The promising selective cytoxicity of PEITC suggests further investigation for its therapeutic implication of oral cancer.