MEL-P, a GM-CSF-producing human melanoma cell line

A human melanoma cell line, MEL-P, expressing granulocyte-macrophage colony-stimulating factor (GM-CSF) and its specific receptor was newly established from a primary nodular lesion of a patient with a particularly unfavourable prognosis. Cytogenetic, immunophenotypic, cytokine and intercellutar adhesion molecule (ICAM)-1 production analyses confirmed that this cell line was similar to the fresh melanoma cells from which it had been established. MEL-P constitutes a valuable model for the study of muItrstep tumour progression and the role of biologically active GM-CSF production in human malignant melanoma. Our results show a decreasing expression of HLA class 1 molecules during in vitro culture, when GM-CSF secretion attains the highest levels, and a constantly high production of ICAM-1. The inhibitory effect of GM-CSF antlsense treatment on cellular growth might suggest the presence of an autocrine mechanism. On the whole, these data are consistent with the possible involvement of high GM CSF production in the metastatic competence of melanoma cells through the autocrine mechanism of growth and/or the activation of other migration-related molecules by its local production in metastatic invasion.