Interferon-gamma and anti-Fas antibody-induced apoptosis in human melanoma cell lines and its relationship to bcl-2 cleavage and bak expression.

Interferon-gamma (IFNgamma) has been shown to induce apoptosis through the induction of the Fas antigen in certain cell lines. In this study, we used four melanoma cell lines (MMN9, PMP, MAA and HMG) to study the antiproliferative effect of exogenous IFNgamma treatment, the expression of IFNgamma-induced Fas antigen, and the combined effect of IFNgamma and anti-Fas antibody (CH-11). We also investigated the relationship between Fas-mediated apoptosis and the expression of the bcl-2 family, measured using Western blotting. IFNgamma increased the mean fluorescence intensity of Fas in MMN9 and PMP cells as measured by flow cytometry. Combined therapy had a significant antiproliferative effect on MMN9 and PMP cells, as measured by the MTT assay. After exposure to IFNgamma and anti-Fas antibody, cleavage of bcl-2 occurred in apoptotic cells, and the signal intensity of both bcl-2 and bak decreased in surviving MMN9 cells, as shown by Western blotting analysis. Our results indicate that IFNgamma induces overexpression of Fas and consequently enhances the sensitivity of melanoma cells to Fas-mediated apoptosis. Furthermore, it is possible that cleavage of bcl-2 correlates with the induction of apoptosis induced by IFNgamma and anti-Fas antibody in melanoma cells. We conclude that combined therapy with IFNgamma and anti-Fas antibody may provide an alternative and more efficient chemotherapeutic approach against melanoma cells by inducing the overexpression of Fas after exposure to IFNgamma.