ANTIPROLIFERATIVE ACTIVITY OF NATURAL INTERFERON-ALPHA, ISOTRETINOIN AND THEIR COMBINATION VARIES IN DIFFERENT HUMAN-MELANOMA CELL-LINES

Natural interferon alpha (nIFN-alpha), isotretinoin and their combinat ion were tested for their capacity to modulate the proliferation of di fferent human melanoma cell lines. Modulation of cell growth was measu red using the MTT-assay. Isotretinoin and nIFN-alpha as single agents inhibited the proliferation in a dose dependent manner in the three ce ll lines: SK-Mel-30, SK-Mel-28 and MaRi. The combination of isotretino in and nIFN-alpha led to a marked enhancement of the antiproliferative effect compared with either nIFN-alpha or isotretinoin alone in SK-Me l-30 cells. In contrast, there were, no additive effects on growth inh ibition of melanoma cell lines SK-Mel-28 and MaRi when nIFN-alpha and isotretinoin was combined. In one melanoma cell line (MaRi) proliferat ion was actually enhanced by isotretinoin in combination with nIFN-alp ha. These results demonstrate the heterogeneous response of human mela noma cell lines to noncytotoxic concentrations of isotretinoin and nIF N-alpha alone and in combination.