Cyclooxygenase-2 promotes hepatocellular carcinoma cell growth through Akt activation: evidence for Akt inhibition in celecoxib-induced apoptosis.
Cyclooxygenase-2 (COX-2)-controlled prostaglandin (PG) metabolism recently has been implicated in the pathogenesis of hepatocellular carcinoma (HCC). However, the biologic role and molecular mechanism of COX-2-mediated PGs in the control of liver cancer growth have not been established. This study was designed to examine the direct effect of COX-2 and its inhibitor celecoxib on the growth control of liver cancer cells. Human HCC cell lines Hep3B and HepG2 transfected with COX-2 expression vector showed increased cell growth and enhanced phosphorylation of serine/threonine protein kinase B (Akt). The level of COX-2 expression and Akt phosphorylation is correlated positively in cultured HCC cells and human liver cancer tissues. Inhibition of Akt activation by phosphatidylinositol 3-kinase (PI3-kinase) inhibitor LY294002 significantly decreased the viability of Hep3B and HepG2 cells (P <.01). These results reveal a novel role of Akt activation in COX-2-induced HCC cell survival. Furthermore, HCC cells treated with the COX-2 inhibitor celecoxib showed significant reduction of Akt phosphorylation and marked morphologic and biochemical characteristics of apoptosis. Overexpression of COX-2 or addition of exogenous PGE(2) partially prevented celecoxib-induced apoptosis (P <.01). In conclusion, our results suggest the involvement of COX-2-dependent and -independent mechanisms in celecoxib-mediated HCC cell apoptosis.
Leng
Jing
J
Department of Pathology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA.
Han
Chang
C
Demetris
A Jake
AJ
Michalopoulos
George K
GK
Wu
Tong
T
D000970:Antineoplastic Agents / Q000494:pharmacology; D017209:Apoptosis; D006528:Carcinoma, Hepatocellular / Q000201:enzymology* / Q000473:pathology*; D000068579:Celecoxib; D002455:Cell Division / Q000187:drug effects; D051546:Cyclooxygenase 2; D052246:Cyclooxygenase 2 Inhibitors; D016861:Cyclooxygenase Inhibitors / Q000494:pharmacology; D015232:Dinoprostone / Q000494:pharmacology; D006801:Humans; D007527:Isoenzymes / Q000378:metabolism* / Q000494:pharmacology; D008113:Liver Neoplasms / Q000201:enzymology* / Q000473:pathology*; D008565:Membrane Proteins; D010766:Phosphorylation; D011451:Prostaglandin-Endoperoxide Synthases / Q000378:metabolism* / Q000494:pharmacology; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins / Q000037:antagonists & inhibitors / Q000187:drug effects / Q000378:metabolism*; D051057:Proto-Oncogene Proteins c-akt; D011720:Pyrazoles; D013449:Sulfonamides / Q000494:pharmacology; D014407:Tumor Cells, Cultured
D000970:Antineoplastic Agents; D052246:Cyclooxygenase 2 Inhibitors; D016861:Cyclooxygenase Inhibitors; D007527:Isoenzymes; D008565:Membrane Proteins; D011518:Proto-Oncogene Proteins; D011720:Pyrazoles; D013449:Sulfonamides; D051546:Cyclooxygenase 2; C496540:PTGS2 protein, human; D011451:Prostaglandin-Endoperoxide Synthases; C494918:AKT1 protein, human; D017346:Protein Serine-Threonine Kinases; D051057:Proto-Oncogene Proteins c-akt; D000068579:Celecoxib; D015232:Dinoprostone