This proposal is to study the formation of melanocyte cell hybrids which contain negative regulatory genes that suppress either the production of melanin or the production of basic fibroblast growth factor. Individual chromosomes from non-pigmented cells will be transferred to melanocytes, and chromosomes from normal melanocytes will be transferred into melanoma cells. Techniques are available to form microcell hybrids which can then be subjected to karyotypic analysis for identification of the individual chromosomes. Tissue specific extinguisher loci have not been well characterized in melanocytes, although they have been characterized in liver cells. In liver cells, down-regulation of target gene expression occurs at the mRNA level; similar experiments will be carried out in melanocytes. %%% Melanocytes produce the pigment melanin under closely regulated conditions. When melanocytes are converted to melanoma cells, which are frequently cancerous, the production of melanin and of a growth factor, basic fibroblast growth factor (bFGF), is increased. This proposal is to prepare microcell hybrids of melanoma cells containing individual chromosomes from normal melanocytes, in order to isolate the specific genes that in normal cells suppress the production of melanin and of bFGF. The individual chromosomes will be identified by standard karyotypic analysis. The molecular structure of the genes involved in suppression will then be determined.
