title: Cyclooxygenase-2 (COX-2)-dependent and -independent anticarcinogenic effects of celecoxib in human colon carcinoma cells.
abstract: Celecoxib, a selective cyclooxygenase-2 (COX-2) inhibitor, is the only non-steroidal anti-inflammatory drug so far which has been approved by the FDA for adjuvant treatment of patients with familial adenomatous polyposis. The molecular mechanism responsible for the anticarcinogenic effects of celecoxib is still not fully understood. To investigate the extent to which the anticarcinogenic effect of celecoxib depends on COX-2 expression, we transfected human colon carcinoma cells (Caco-2) with the human COX-2 cDNA, in both sense and in antisense orientation, to generate cells which either overexpress COX-2 (human COX-2-sense, hCOX-2-s), express no COX-2 (human COX-2-antisense, hCOX-2-as) or express only very small amounts of COX-2 (control cells). Treatment of these cells with celecoxib dose-dependently (0-100microM) reduced cell survival which was accompanied by an induction of a G(0)/G(1) phase block and apoptosis. The effect of celecoxib treatment on both, cell survival and induction of apoptosis in hCOX-2-as cells was less marked than in the COX-2-expressing cells. Apoptosis was accompanied by an activation of caspase-3 and caspase-9 and cytochrome c release. In contrast, we observed no difference in sensitivity with regard to the induction of a cell cycle block between the different cell clones. The G(0)/G(1) phase block caused by celecoxib correlated with a decrease in expression levels of cyclin A and cyclin B1 and an increase in the expression of the cell cycle inhibitory proteins p21(Waf1) and p27(Kip1) irrespective of the type of cell used. These data indicate that apoptosis-inducing effects of celecoxib partly depend on COX-2 expression of the cells, whereas induction of a cell cycle block occurred COX-2 independently. Thus, the anticarinogenic effects of celecoxib can be explained by both COX-2-dependent and -independent mechanisms.
authors.affiliation: Pharmazentrum Frankfurt, Klinikum der Johann Wolfgang Goethe Universität Frankfurt, Theodor Stern Kai 7, Frankfurt/Main 60590, Germany. tmaier@stud.uni-frankfurt.de
authors.forename: Thorsten Jürgen
authors.initials: TJ
authors.lastname: Maier
authors.forename: Karin
authors.initials: K
authors.lastname: Schilling
authors.forename: Ronald
authors.initials: R
authors.lastname: Schmidt
authors.forename: Gerd
authors.initials: G
authors.lastname: Geisslinger
authors.forename: Sabine
authors.initials: S
authors.lastname: Grösch
mesh_terms: D016588:Anticarcinogenic Agents / Q000494:pharmacology*; D017209:Apoptosis; D018938:Caco-2 Cells; D000068579:Celecoxib; D002453:Cell Cycle / Q000187:drug effects; D018797:Cell Cycle Proteins / Q000378:metabolism; D002470:Cell Survival / Q000187:drug effects; D003110:Colonic Neoplasms; D019925:Cyclin A / Q000378:metabolism; D019926:Cyclin B / Q000378:metabolism; D056744:Cyclin B1; D050759:Cyclin-Dependent Kinase Inhibitor p21; D050760:Cyclin-Dependent Kinase Inhibitor p27; D016213:Cyclins / Q000378:metabolism; D051546:Cyclooxygenase 2; D006801:Humans; D007527:Isoenzymes / Q000378:metabolism / Q000502:physiology*; D008565:Membrane Proteins; D011451:Prostaglandin-Endoperoxide Synthases / Q000378:metabolism / Q000502:physiology*; D011720:Pyrazoles; D013449:Sulfonamides / Q000494:pharmacology*; D014407:Tumor Cells, Cultured; D025521:Tumor Suppressor Proteins / Q000378:metabolism
chemical_list: D016588:Anticarcinogenic Agents; C534699:CCNB1 protein, human; C493956:CDKN1A protein, human; D018797:Cell Cycle Proteins; D019925:Cyclin A; D019926:Cyclin B; D056744:Cyclin B1; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins; D007527:Isoenzymes; D008565:Membrane Proteins; D011720:Pyrazoles; D013449:Sulfonamides; D025521:Tumor Suppressor Proteins; D050760:Cyclin-Dependent Kinase Inhibitor p27; D051546:Cyclooxygenase 2; C496540:PTGS2 protein, human; D011451:Prostaglandin-Endoperoxide Synthases; D000068579:Celecoxib