The in vitro effects of H-89, a specific inhibitor of protein kinase A, in the human colonic carcinoma cell line Caco-2.
H-89 is a compound characterized in vitro as a potent and selective inhibitor of protein kinase A. In the present study, we observed that H-89 induced morphological transformation and caused growth inhibition of the human colon cancer cell line Caco-2 in a dose-dependent manner. However, another protein kinase A inhibitor, H-8, had no effect on Caco-2 cells. To evaluate the possible molecular mechanism of H-89-evoked effects in Caco-2 cells, we analysed the capacity of H-89 to regulate the protein kinase B (Akt/PKB) signalling pathway. H-89 treatment led to an activation of Akt/PKB in Caco-2 cells. This activation was phosphatidylinositol 3 (PI3)-kinase-dependent and promoted survival of Caco-2 cells because the PI3 kinase inhibitor LY294002 inhibited the Akt/PKB activation and induced apoptosis of Caco-2 cells. To test whether Akt/PKB activity promoted resistance to H-89-induced effects, LY294002 was added in combination with H-89. LY294002 greatly potentiated the H-89-induced growth inhibition and apoptosis of Caco-2 cells. These results suggest that the H-89-induced growth inhibition of Caco-2 cells is associated with phosphorylation of Akt/PKB protein and that the cells become more sensitive to H-89 and die by apoptosis upon inhibition of the PI3K/Akt pathway.
Böckmann
S
S
Centre for Pharmacology and Toxicology, Institute of Experimental Pharmacology, Germany. sabine.boeckmann@med.uni-rostock.de
Nebe
B
B
D064413:3-Phosphoinositide-Dependent Protein Kinases; D018938:Caco-2 Cells; D002277:Carcinoma / Q000473:pathology*; D002455:Cell Division / Q000187:drug effects*; D003110:Colonic Neoplasms / Q000473:pathology*; D017868:Cyclic AMP-Dependent Protein Kinases / Q000037:antagonists & inhibitors; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D006801:Humans; D007546:Isoquinolines / Q000494:pharmacology*; D047428:Protein Kinase Inhibitors; D017346:Protein Serine-Threonine Kinases / Q000494:pharmacology; D011518:Proto-Oncogene Proteins / Q000494:pharmacology; D051057:Proto-Oncogene Proteins c-akt; D015398:Signal Transduction; D013449:Sulfonamides; D014407:Tumor Cells, Cultured
D004791:Enzyme Inhibitors; D007546:Isoquinolines; D047428:Protein Kinase Inhibitors; D011518:Proto-Oncogene Proteins; D013449:Sulfonamides; D064413:3-Phosphoinositide-Dependent Protein Kinases; C494918:AKT1 protein, human; D017346:Protein Serine-Threonine Kinases; D051057:Proto-Oncogene Proteins c-akt; D017868:Cyclic AMP-Dependent Protein Kinases; C063509:N-(2-(4-bromocinnamylamino)ethyl)-5-isoquinolinesulfonamide