Proliferation of human melanoma cells is under tight control of protein kinase C alpha

Exponential proliferation of human melanoma cells has been associated with low levels of protein kinase C (PKC)-{alpha}. The aim of the present study was to investigate the functional relationship between PKC-{alpha} and melanoma cell proliferation. Treatment of human melanoma cells with the selective PKC inhibitor Ro-31-8220 resulted in a significant increase of cell proliferation as measured by (3)H-thymidine incorporation and a fluorometric microassay. In addition, phosphorothioate antisense-oligodeoxynucleotides (ODNs) to PKC-{alpha} enhanced DNA-synthesis of human melanoma cells. Furthermore, microinjection and transient transfection of melanoma cells with PKC-{alpha} decreased their proliferation, as shown by the reduction of nuclear staining with the proliferation marker Ki-67. The presented data demonstrate a cause-effect relationship between PKC-{alpha} and melanoma cell growth, whereby PKC-{alpha} reversely influences the rate of cell proliferation