Higher levels of melanin and inhibition of cdk2 activity in primary human melanoma cells WM115 overexpressing nPKCδ

Abstract

Many studies have attempted to define the state of differentiation of melanoma cells and to correlate it with other critical parameters of malignancy such as the tumorigenic and metastatic nature of the cells. In the present paper we focused on the possible relationships between the novel protein kinase C isoform nPKCδ, melanin synthesis and proliferative capacity in a primary human melanoma cell line WM115. Cells were transfected to produce overexpression of this isoform and the effects on melanin synthesis, cyclin-E dependent kinase (cdk2) activity and cyclin E expression were studied. It was shown that translocation of nPKCδ into the nucleus affects melanin synthesis and inhibits cdk2 activity. As a compensatory effect, the level of cyclin E increases. In view of these results we suggest a model for the role of nPKCδ in melanoma cells that may offer a new therapeutic perspective.