GH3B6 pituitary tumor cell proliferation is mediated by PKCalpha and PKCepsilon via ERK 1/2-dependent pathway.
BACKGROUND
In this report, we explored the role of PKCalpha and PKCe 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.


METHODS
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 PKCe in membrane and cytosolic fractions by western blotting. The subcellular redistribution of both PKC isozymes was analyzed by confocal microscopy.


RESULTS
Incubation with PMA for 15 min stimulated PKCalpha and PKCe activation, which was correlated with the 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 in GH3B6 cells, an effect that was blocked by the inhibitors of PKCalpha (Gö6976) and PKCe (eV1-2). In addition, the pretreatment with the inhibitor of ERK1/2 (PD98059) prevented the mitogenic activity induced by treatment with PMA for 15 min.


CONCLUSIONS
We demonstrated that the activation of PKCalpha and PKCe by phorbol ester in tumor pituitary GH3B6 cells led to cell proliferation and cell cycle progression, effects that involved ERK1/2 activation.
Petiti
Juan Pablo
JP
Centro de Microscopía Electrónica, Facultad de Ciencias Médicas, Universidad Nacional de Córdoba, Córdoba, Argentina. jpetiti@cmefcm.uncor.edu
Gutiérrez
Silvina
S
De Paul
Ana Lucía
AL
Andreoli
Verónica
V
Palmeri
Claudia Mariela
CM
Sosa
Liliana Del Valle
Ldel V
Bocco
José Luis
JL
Torres
Alicia Inés
AI
D000818:Animals; D001973:Bromodeoxyuridine / Q000494:pharmacology; D049109:Cell Proliferation; D005419:Flavonoids / Q000494:pharmacology; D005434:Flow Cytometry; D019950:Mitogen-Activated Protein Kinase 1 / Q000037:antagonists & inhibitors / Q000378:metabolism*; D048052:Mitogen-Activated Protein Kinase 3 / Q000037:antagonists & inhibitors / Q000378:metabolism*; D010766:Phosphorylation; D010911:Pituitary Neoplasms / Q000201:enzymology*; D051571:Protein Kinase C-alpha / Q000037:antagonists & inhibitors / Q000378:metabolism*; D051744:Protein Kinase C-epsilon / Q000037:antagonists & inhibitors / Q000378:metabolism*; D051381:Rats; D015398:Signal Transduction; D013755:Tetradecanoylphorbol Acetate / Q000031:analogs & derivatives / Q000494:pharmacology; D014407:Tumor Cells, Cultured
D005419:Flavonoids; C020922:4-O-methyl-12-O-tetradecanoylphorbol 13-acetate; D051571:Protein Kinase C-alpha; D051744:Protein Kinase C-epsilon; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D001973:Bromodeoxyuridine; D013755:Tetradecanoylphorbol Acetate; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one