Downregulation of Bcl-2 and activation of caspase-8 in the UVB-induced apoptosis of a cultured human melanoma cell line.

Purpose: This study was performed to determine the effect of UV radiation on the activation of apoptosis regulatory proteins using cultured human melanoma cells. Methods: G361 lightly pigmented melanoma cells were irradiated with increasing doses of UVB and analyzed for an apoptotic mechanism using a cell viability test, TEM, FACS, and western blotting analysis. Results: TEM and FACS showed apoptotic features of cell death after UVB irradiation. Western blotting disclosed downregulation of Bcl-2 and the activation of caspase-9. Caspase-8, a downstream molecule of Fas/FasL interaction, was also activated. The activation of downstream molecules of both caspase-8 and caspase-9 was also demonstrated. Conclusion: Our data showed that the regulation of the Bcl-2 family and caspase-8 may work together to activate a caspase-3 mediated apoptotic pathway following UVB irradiation of cultured human melanoma cells.