Tumor cells often display alterations in their normal program of cellular differentiation. A promising approach for the treatment of cancer involves the induction of terminal differentiation and a loss of proliferative capacity in cancer cells. In human melanoma cells, the combination of mezerein (MEZ) and fibroblast interferon (IFN-beta), results in a rapid and irreversible suppression of cell growth with a concomitant increase in the synthesis of melanin. The induction of terminal differentiation is associated with alterations in the expression of several cellular genes, including fibronectin, ISG-15 and ISG-54, and changes in the expression of specific cell surface antigens, including intercellular adhesion molecule-1 (ICAM-1) and HLA Class I antigens. In the HO-1 human melanoma cell line, induction of terminal differentiation by MEZ plus IFN-beta results in an induction and/or increased expression of ICAM-1, HLA Class I antigens and HLA Class II antigens. IFN-beta and MEZ alone can modulate expression of these antigens to a lower extent than does the combination of compounds. Induction of terminal differentiation and the irreversible suppression of cell growth is not a prerequisite for antigenic modulation in HO-1 cells. This is indicated by the inability of immune interferon (IFN-gamma), a strong inducer of ICAM-1, HLA Class I antigens and HLA Class II antigens synthesis, or the combination of IFN-beta plus IFN-gamma which synergistically but reversibly suppresses HO-1 growth, to induce melanin synthesis or terminal differentiation in HO-1 cells.(ABSTRACT TRUNCATED AT 250 WORDS)