B16-G4F MOUSE MELANOMA-CELLS - AN MSH RECEPTOR-DEFICIENT CELL CLONE

The two mouse melanoma cell lines B16-F1 and B16-G4F retain their mela nogenic capacity when cultured in vitro. Melanotropic peptides such as alpha-melanocyte-stimulating hormone (alpha-MSH) induce formation and release of melanin pigment in B16-F1 cells. In contrast, B16-G4F cell s do not respond to alpha-MSH. Using receptor-binding analysis and pho toaffinity crosslinking we demonstrate that the lack of response of B1 6-G4F cells to alpha-MSH is due to the absence of functional MSH recep tors from the cell surface. Northern blot analysis of receptor mRNA re vealed that MSH receptor mRNA is not expressed in B16-G4F cells. These cells represent a new tool for the study of signal pathways related t o the control of melanogenesis in melanoma cells.