title: Akt regulates COX-2 mRNA and protein expression in mutated-PTEN human endometrial cancer cells.
abstract: In human endometrial cancer, the fourth most common cancer in women, tumor suppressor phosphatase tensin homologue (PTEN) is frequently mutated. In the presence of a mutated PTEN protein, Akt phosphorylation levels are increased leading to the activation of this survival pathway. Numerous studies indicated that COX-2 is inappropriately induced and up-regulated in a number of malignant cancer cells. COX-2 plays an important role in tumor cell biology, taking part actively in angiogenesis particularly via the production of prostaglandin E2 (PGE2). The present study was undertaken to determine the involvement of PI 3-K/Akt pathway in the regulation of COXs expression and PGE2 synthesis. Three different human endometrial cancer cell lines known to have wild-type PTEN (HEC 1-A) or a mutated inactive PTEN protein (RL 95-2 and Ishikawa) were used for these studies. Results showed that Akt phosphorylation was high in mutated PTEN cells. RT-PCR studies revealed that Akt1 and Akt2 were the regulated forms whereas Akt3 mRNA was nearly undetectable. COX-2 mRNA expression and protein levels were high in these cells compared to wild-type PTEN cells as demonstrated by RT-PCR and Western analysis respectively. PGE2 production was higher in mutated-PTEN expressing phospho-Akt and COX-2 compared to wild-type PTEN cells. Inhibition of PI 3-K with Wortmannin and LY294002 blocked Akt phosphorylation and inhibited expression of COX-2 in mutated-PTEN cells. Inhibition of Akt phosphorylation with specific PI 3-K inhibitors and down-regulation of COX-2 increased apoptosis in human endometrial cancer cells. Likewise, transfection of mutated-PTEN cells with a dominant negative Akt vector, resulted in COX-2 down-regulation and activation of apoptosis, as demonstrated by Hoechst nuclear staining. On the opposite, activation of Akt using a constitutively active expression vector, resulted in the up-regulation of COX-2 protein expression. Specific inhibition of COX-2 with NS-398 induced apoptosis in COX-2 expressing human endometrial cancer cells. It is concluded that the PI 3-K/Akt survival pathway is involved in the regulation of COX-2 and PGE2 synthesis in human endometrial cancer cells.
authors.affiliation: Department of Chemistry and Biology, Medical Biology Section, University of Quebec at Trois-Rivieres, C.P. 500, Trois-Rivieres, Quebec G9A 5H7, Canada.
authors.forename: Marie-Eve
authors.initials: ME
authors.lastname: St-Germain
authors.forename: Veronique
authors.initials: V
authors.lastname: Gagnon
authors.forename: Isabelle
authors.initials: I
authors.lastname: Mathieu
authors.forename: Sophie
authors.initials: S
authors.lastname: Parent
authors.forename: Eric
authors.initials: E
authors.lastname: Asselin
mesh_terms: D017209:Apoptosis; D015153:Blotting, Western; D051546:Cyclooxygenase 2; D052246:Cyclooxygenase 2 Inhibitors; D016861:Cyclooxygenase Inhibitors / Q000494:pharmacology; D015232:Dinoprostone / Q000378:metabolism; D016889:Endometrial Neoplasms / Q000378:metabolism* / Q000473:pathology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D015971:Gene Expression Regulation, Enzymologic; D015972:Gene Expression Regulation, Neoplastic; D005799:Genes, Dominant; D006801:Humans; D007527:Isoenzymes / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D008565:Membrane Proteins; D009154:Mutation / Q000235:genetics*; D009578:Nitrobenzenes / Q000494:pharmacology; D051059:PTEN Phosphohydrolase; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D010744:Phosphoric Monoester Hydrolases / Q000235:genetics* / Q000378:metabolism; D010766:Phosphorylation; D011451:Prostaglandin-Endoperoxide Synthases / Q000235:genetics / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D011518:Proto-Oncogene Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D051057:Proto-Oncogene Proteins c-akt; D012333:RNA, Messenger; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013449:Sulfonamides / Q000494:pharmacology; D014407:Tumor Cells, Cultured; D025521:Tumor Suppressor Proteins / Q000235:genetics* / Q000378:metabolism
chemical_list: D051546:Cyclooxygenase 2; D052246:Cyclooxygenase 2 Inhibitors; D016861:Cyclooxygenase Inhibitors; D015232:Dinoprostone; D004791:Enzyme Inhibitors; D007527:Isoenzymes; D008565:Membrane Proteins; D009578:Nitrobenzenes; D051059:PTEN Phosphohydrolase; D019869:Phosphatidylinositol 3-Kinases; D010744:Phosphoric Monoester Hydrolases; D011451:Prostaglandin-Endoperoxide Synthases; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins; D051057:Proto-Oncogene Proteins c-akt; D012333:RNA, Messenger; D013449:Sulfonamides; D025521:Tumor Suppressor Proteins; C080955:N-(2-cyclohexyloxy-4-nitrophenyl)methanesulfonamide; C496540:PTGS2 protein, human; C494918:AKT1 protein, human; C494921:AKT2 protein, human; C494929:PTEN protein, human