Proapoptotic and antiproliferative potential of selective cyclooxygenase-2 inhibitors in human liver tumor cells.
Recent studies have shown increased levels of cyclooxygenase-2 (COX-2) in a variety of human malignancies, including hepatocellular carcinoma (HCC), but so far it is unknown whether COX-2 contributes to the malignant growth and whether inhibition of COX-2 function modifies the malignant potential of liver tumors. COX-1 and COX-2 expression was determined in 4 liver tumor cell lines (Hep 3B, HuH-7, Hep G2, Sk-hep1) by Northern hybridization and Western immunoblot. The functional effects of the nonselective inhibitor sulindac sulfide and the COX-2 selective inhibitors SC-58635 and meloxicam were examined by 3(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazoliumbromide (MTT)-assays and BrdU uptake, morphology, and TUNEL analysis of apoptosis. Apoptosis regulating proteins were analyzed by Western immunoblot. COX-1 and COX-2 expression was demonstrable in all tested liver tumor cell lines. Sulindac sulfide (50 to 400 micromol/L), SC-58635 (6,25 to 400 micromol/L), and meloxicam (6.25 to 400 micromol/L) led to a significant time- and dose-dependent reduction of cell numbers of up to 80% (P <.05). At equimolar concentrations the effect was more pronounced when COX-2 was selectively blocked. COX-2 inhibition induced apoptosis and reduced tumor cell proliferation. Apoptosis after COX-2 inhibition with SC-58635 (50 micromol/L) was independent of BCL-2, BAX, and the phosphorylation status of AKT/PKB and BAD, but correlated with activation of caspase-9, caspase-3, and caspase-6. In conclusion, selective inhibition of COX-2 leads to a marked growth inhibition of human liver tumor cells, based on the induction of apoptosis and inhibition of proliferation and, thus, may offer therapeutic and preventive potential in human hepatocarcinogenesis.
Kern
Michael André
MA
Institute of Pathology, University of Cologne, Germany.
Schubert
Dominic
D
Sahi
Dina
D
Schöneweiss
Mirja Mareike
MM
Moll
Ilona
I
Haugg
Anke Maria
AM
Dienes
Hans Peter
HP
Breuhahn
Kai
K
Schirmacher
Peter
P
D017209:Apoptosis / Q000187:drug effects*; D006528:Carcinoma, Hepatocellular; D002352:Carrier Proteins / Q000378:metabolism; D020169:Caspases / Q000378:metabolism; D000068579:Celecoxib; D002455:Cell Division / Q000187:drug effects; D051546:Cyclooxygenase 2; D052246:Cyclooxygenase 2 Inhibitors; D016861:Cyclooxygenase Inhibitors / Q000494:pharmacology*; D006801:Humans; D007527:Isoenzymes / Q000037:antagonists & inhibitors*; D008113:Liver Neoplasms; D000077239:Meloxicam; D008565:Membrane Proteins; D010766:Phosphorylation; D011451:Prostaglandin-Endoperoxide Synthases; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D011720:Pyrazoles; D013449:Sulfonamides / Q000494:pharmacology*; D013843:Thiazines / Q000494:pharmacology; D013844:Thiazoles / Q000494:pharmacology; D014407:Tumor Cells, Cultured / Q000166:cytology / Q000201:enzymology; D051028:bcl-2-Associated X Protein; D051025:bcl-Associated Death Protein
C494819:BAD protein, human; C494826:BAX protein, human; D002352:Carrier Proteins; D052246:Cyclooxygenase 2 Inhibitors; D016861:Cyclooxygenase Inhibitors; D007527:Isoenzymes; D008565:Membrane Proteins; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D011720:Pyrazoles; D013449:Sulfonamides; D013843:Thiazines; D013844:Thiazoles; D051028:bcl-2-Associated X Protein; D051025:bcl-Associated Death Protein; 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; D020169:Caspases; D000068579:Celecoxib; D000077239:Meloxicam