ACTIVATION OF PKCalpha AND PKCepsilon INDUCES TUMORAL LACTOTROPH PROLlFERATION VIA ERK1/2

PETITI, J. P.; GUTIERREZ, S.; DE PAUL, A L; ANDREOLI, V.; MUKDSI, J. H.; SOSA LDEL, V.; BOCCO, J. L.; TORRES, A I

Congreso; The First South American Spring Symposium in Signal Transduction and Molecular Medicina; 2010

We explored the role of PKCalpha and PKCepsilon as mediators of phorbol 12- myristate13-acetate (PMA)-induced proliferation in pituitary tumor GH3B6 cells, and determined if the ERK1/2 and Akt pathways were activated. The GH3B6 cell proliferation was estimated by BrdU incorporation and the cell cycle progression by flow cytometric cell cycle analysis. We determined the expression of PKCalpha and PKCepsilon;in membrane and cytosolic fractions by western blotting. The subcellular redistribution of both PKC isozymes was analyzed by confocal and immunogold electron microscopy. Incubation with PMA for 15 min stimulated PKCalpha and PKCepsilon activation, which was correlated with its translocation to plasma and nuclear membrane and phosphorylation of ERK1/2 but not Akt. The activation of both these PKC isozymes was closely associated with the stimulation of proliferation and the cell cycle progression induced by PMA, an effect that was blocked by the inhibitors of PKCalpha (G66976) and PKCepsilon (eV1-2). In addition, -the pretreatment with the inhibitor of ERK1/2 (PD98059) prevented the mitogenic activity induced by PMA for 15 mino We demonstrated that the activation of PKCalpha and PKCepsilon by phorbol ester in tumor pituitary GH3B6 cells led to cell proliferation via ERK1/2.