Interleukin--1#beta# induces apoptosis in human melanoma A375--S2 cells through mitochondrial pathway by activating caspase--3

Objective To investigate the mechanism of IL-1β-induced cell apoptosis in human malignant melanoma A375-S2 cells. Methods The morphologic changes of cell were observed by using Hoechst 33258 staining. DNA fragmentation was detected by agarose gel electrophoresis. Caspase-3 activity was assessed by assaying the activity of caspase. The degradation of caspase-3 substrates and the protein expression of DBcl-2 family and AIF were assayed by Western blotting. Results Cell nuclear condensation was observed after treatment with IL-1β for 48 h and DNA fragmentation was observed at 72 h. In apoptotic progress induced by IL-1β, caspase-3 activation was augmented and its two substrates, PARP and ICAD proteins, were degradation. Expressions of antiapoptotic Bcl-2 and Bcl-x_L were decreased, but proapoptotic Bax expression was slightly increased. Furthermore, AIF expression was up-regulated. Conclusion IL-1β induces apoptosis in A375-S2 cells by activating caspase-3 and AIF, as well as up-regulating the ratio of the Bax/Bcl-2 expression to Bax/Bcl-x_L expression.