Nerve growth factor chromatin receptor and cell surface receptor-regulated growth of melanocytes and nevus cells

Abstract

RNA synthesis in melanocytes and nevus cells, and the proliferation of those cells in the presence of nerve growth factor (NGF) and 12-0-tetradecanoyl-phorbol-13-acetate (TPA), were found to correlate with the amount of NGF bound to the chromatin versus the total internalized NGF (n/c NGF = nuclear/cellular ration). In nevus cells and in melanocytes of the early passages (n/c NGF = 0.16-0.18), NGF slightly activated RNA synthesis but was without any effect on cell growth. At passage 5-6 of melanocytes (n/c NGF = 0.88), NGF inhibited RNA synthesis, which led to inhibition of cell growth. Removal of TPA from the culture of nevus cells resulted in increased n/c NGF ratio and in a switch from activatory to inhibitory action of NGF. The possibility that the cell surface receptor mediated the stimulatory effect of NGF and may antagonize the chromatin receptor-mediated inhibitory effect of NGF of melanocyte and nevus cell growth is discussed.