CARBON IONS INDUCE DNA DOUBLE STRAND BREAKS AND APOPTOSIS IN HTB140 MELANOMA CELLS

This study was conducted in order to evaluate the ability of carbon ions to induce DNA double-strand breaks and apoptosis in the radio-resistant human HTB140 melanoma cells. The cells were irradiated with C-12 ions having the linear energy transfer of 258 keV/mu m. Irradiations were performed in the dose range from 2 to 16 Gy. Induction of DNA double-strand breaks was evaluated 2 hour after irradiation through expression of gamma H2AX protein. Increased level of gamma H2AX detected in irradiated samples was especially high after irradiation with 12 and 16 Gy. Dose dependent increase of apoptosis was detected 48 hour after irradiation by flow-cytometry, with the maximum value of 20.4% after irradiation with 16 Gy, and the apoptotic index of 9.3. Pro-apoptotic effects of carbon ion beams were confirmed by changes of key molecules of the mitochondrial apoptotic pathway, p53 protein expression, Bax/Bcl-2 ratio and caspase-3 activation.