Involvement of the α Isoenzyme of Protein Kinase C in the Growth Inhibition Induced by Phorbol Esters in MH1C1 Hepatoma Cells

Abstract

MH1C1 rat hepatoma cells express the α isoenzyme as the only phorbol-ester sensitive isoform of protein kinase C (PKC). In this cell line, phorbol 12-myristate 13-acetate (PMA) induced a marked, dose-dependent growth inhibition. The administration of the PKC inhibitor staurosporine was able to mimic the effect of the phorbol ester on cell growth in a dose-dependent fashion, whereas the PKC activator arachidonic acid stimulated cell proliferation. Exposure of cells to an antisense oligonucleotide specific for αPKC caused a significant impairment of cell growth. These data suggest that the αPKC activity is required for proliferation of MH1C1 cells.