INTERTUMORAL HETEROGENEITY OF RECEPTOR-TYROSINE KINASES EXPRESSION INHUMAN-MELANOMA CELL-LINES WITH DIFFERENT METASTATIC CAPABILITIES

Human melanocytes respond to several growth factors whose receptors ha ve tyrosine kinase activity. Abnormalities in the expression of tyrosi ne kinase receptors may play an important role in the initiation and p rogression of melanoma. We therefore determined the steady-state mRNA expression of five tyrosine kinase receptors, epidermal growth factor receptor (EGF-R), c-met, nerve growth factor receptor (NGF-R), colony- stimulating factor receptor (CSF-R) and c-kit, in eleven human melanom a cell lines with different metastatic potentials in nude mice. All ce ll lines except for one nonmetastatic fine established from a primary melanoma lost expression of c-kit. Expression of the other four tyrosi ne kinase receptors varied among the lines. The expression level of in dividual tyrosine kinase receptor did not correlate with the metastati c potential of the cells. These results suggest Chat metastatic human melanoma cell lines are heterogeneous for expression of tyrosine kinas e receptors, with each cell type manifesting a distinct repertoire of receptor tyrosine kinases. The different profile of tyrosine kinase ac tivities in different metastatic melanomas complicates its use for pro gnosis.