Cyclooxygenase-2 expression inhibits trophic withdrawal apoptosis in nerve growth factor-differentiated PC12 cells.
Cyclooxygenase-2 (Cox-2), an enzyme responsible for catalyzing the committed step in prostanoid biosynthesis, is the product of an immediate early gene capable of being up-regulated by diverse stimuli. Significantly Cox-2 mRNA is absent from rat pheochromocytoma (PC12) cells, both basally and following stimulation with a range of agonists. Using PC12 cells engineered to stably express isopropyl-1-thio-beta-D-galactopyranoside-inducible Cox-2 (PCXII-4), we have investigated the putative effects of Cox-2 expression on differentiation, proliferation, and trophic withdrawal apoptosis. Cox-2 bioactivity had no effect on nerve growth factor-induced differentiation, epidermal growth factor-induced proliferation, or aromatic L-amino acid decarboxylase expression. However, trophic withdrawal apoptosis, induced by the removal of nerve growth factor following differentiation, was markedly reduced in the PCXII-4 when compared with control cells, as assessed by annexin V staining, DNA laddering, and Hoechst 33258 staining. The specificity of this effect was confirmed using two pharmacologically distinct nonsteroidal anti-inflammatory drugs, indomethacin and NS398. Investigations showed that the activity of the pro-apoptotic protease caspase-3 was reduced in PCXII cells. This study demonstrates that Cox-2-derived prostaglandins exert cytoprotective effects in trophic factor withdrawal apoptosis and provides evidence that this is, at least in part, due to suppression of caspase-3 activity.
McGinty
A
A
Department of Medicine and Cardiovascular Research Center, Medical College of Wisconsin, Milwaukee, Wisconsin 53226, USA.
Chang
Y W
YW
Sorokin
A
A
Bokemeyer
D
D
Dunn
M J
MJ
D000818:Animals; D017209:Apoptosis / Q000502:physiology*; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism; D002454:Cell Differentiation; D051546:Cyclooxygenase 2; D004790:Enzyme Induction; D004815:Epidermal Growth Factor / Q000502:physiology; D007527:Isoenzymes / Q000096:biosynthesis* / Q000235:genetics; D007544:Isopropyl Thiogalactoside / Q000494:pharmacology; D009414:Nerve Growth Factors / Q000502:physiology*; D016716:PC12 Cells; D011451:Prostaglandin-Endoperoxide Synthases / Q000096:biosynthesis* / Q000235:genetics; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats
D007527:Isoenzymes; D009414:Nerve Growth Factors; D012333:RNA, Messenger; D007544:Isopropyl Thiogalactoside; D004815:Epidermal Growth Factor; D051546:Cyclooxygenase 2; D011451:Prostaglandin-Endoperoxide Synthases; C505410:Casp3 protein, rat; D053148:Caspase 3; D020169:Caspases