Suphaket Saenthaweesuk

Antiproliferative and apoptotic effects of high-dose vitamin C in cholangiocarcinoma cell line

Purpose : To evaluate the antiproliferative and apoptotic effects of high-dose vitamin C in cholangiocarcinoma cell line (CCA). Methods : Sulforhodamine B colorimetric assay was used to determine cell proliferation in human K100- CCA cell lines. The expression of anti-apoptotic Bcl-2 protein/ pro-apoptotic Bax protein was evaluated by Western blot analysis. Results : Ascorbic acid inhibited the growth of CCA in a dose-dependent manner. The half-maximal inhibitory concentration (IC 50 ) of ascorbic acid on K100 at 24 h was 55 ± 9.4 mM. It was observed that treatment with ascorbic acid resulted in the reduction of glutathione and increased hydrogen peroxide contents in the cells. Moreover, disturbance of mitochondrial membrane potential occurred in ascorbic acid-treated cells in a dose-dependence manner. The ratio of Bcl2/Bax decreased in CCA treated with ascorbic acid. Conclusion : The results show that the anti-proliferation effect of ascorbic acid in CCA may be attributable to the modulation of expressions of Bcl-2 and Bax proteins and dissipation of the mitochondrial electrochemical potential gradient, which is an early event leading to apoptosis. Keywords : Vitamin C, Cholangiocarcinoma, Apoptosis, Glutathione, Mitochondrial membrane potential