role of caspases and reactive oxygen species in rose bengal-induced toxicity in melanoma cells

objective we have previously shown that rose bengal (rb) alone, not as a photosensitiser, could induce apoptotic- and non-apoptotic cell death in different melanoma cell lines. to clarify rb-induced toxicity mechanisms, role of caspases and reactive oxygen specious (ros) were studied in melanoma cells. material and methods human melanoma cell lines, me 4405 and sk-mel-28 were cultured in dmem medium. cell viability was quantitated by mtt assay. apoptotic cells were determined using pi staining of dna fragmentation by flow cytometry (sub-g1 peak). role of caspase were studied using the pan-caspase inhibitor, z-vad-fmk. ros was measured using dcf-da by flow cytometry analysis. results this study showed that whilez-vad-fmk completely inhibited apoptosis of melanoma inducedby tumor necrosis factor (tnf)-related apoptosis-inducing ligand(trail), it only partiallyblocked rb-induced apoptosis in me4405 and sk-mel-28 melanoma cell lines. rb also increased ros production in melanoma cells but pretreatment with antioxidant -glutamylcysteinylglycine (gsh) could not decrease rb-induced toxicity. conclusion both caspase-dependent and -independent pathways were inducedby rb in melanoma cells. rb-induced generation of ros does not playa significant role in rb-induced toxicity and it is independent of ros production in melanoma cells.