CHARACTERIZATION OF PROTEIN-KINASE-C IN RAT AND HUMAN PROSTATES

The properties of protein kinase C (PKC) activity have been studied in cytosolic and membrane fractions from rat and human prostate. ion exc hange chromatography indicated the existence of different PKC isoforms , PKC from rat ventral prostate behaved as a classical Ca2+ and phosph olipid-dependent enzyme and was activated by 1,2-diacylglycerol as wel l as by high concentrations of arachidonic acid. PKC activity in the c ytosolic fraction was higher and presented different cofactor requirem ents than that in the membrane fraction. PKC from human benign hyperpl astic prostate was also phospholipid dependent, activated by tumor-pro motong phorbol esters, and appeared to belong to the group of PKC isoz ymes which lack Ca2+ sensitivity. Human prostatic PKC activity appeare d to be of similar nature in both membrane and cytosolic fractions but the specific activity was higher in the particulate preparation which could be related to the stage of endogenous activation of the enzyme. These results extend previous observations in rat ventral prostate an d present evidences on the human counterpart. Forthcoming experiments are needed to establish the exact nature of PKC isozymes and their phy siological and pathophysiological role in this gland.