title: Cyclooxygenase-2 overexpression inhibits cathepsin D-mediated cleavage of plasminogen to the potent antiangiogenic factor angiostatin.
abstract: Overexpression of cyclooxygenase (COX)-2 and enhanced synthesis of prostaglandin E2 (PGE2) have been implicated in human endometrial pathologies. To investigate the molecular role of COX-2, the Ishikawa human endometrial epithelial cell line was stably transfected with the pIRES2 vector containing COX-2 cDNA in either the sense or antisense directions. PGE2 concentrations were significantly elevated in the cells transfected with the COX-2 sense compared with wild-type cells or cells transfected with the antisense cDNA (P < 0.01). Elevated PGE2 synthesis was associated with enhanced expression and signaling of PGE2 receptors (EP). cDNA array analysis revealed differential expression of cathepsin D between the COX-2 sense and antisense cells. Cathepsin D RNA and protein expression was 6.7- and 2.1-fold lower in the COX-2 sense compared with COX-2 antisense cells respectively. Cathepsin D is known to cleave plasminogen to the potent antiangiogenic factor angiostatin. To investigate differential angiostatin generation, conditioned media from COX-2 sense, COX-2 antisense and wild-type cells were incubated with plasminogen and subsequently subjected to Western blot analysis. In comparison to wild-type cells, the cleavage of plasminogen to angiostatin was abolished when incubated in COX-2 sense cells conditioned media and elevated when incubated in COX-2 antisense cells conditioned media. Coincubation of plasminogen with the cathepsin D inhibitor pepstatin A inhibited the cleavage of plasminogen to angiostatin in the COX-2 antisense conditioned media. These data demonstrate that COX-2 exerts a negative feedback on the expression of cathepsin D. This in turn reduces the generation of the antiangiogenic factor angiostatin, hence promoting a proangiogenic environment.
authors.affiliation: Medical Research Council Human Reproductive Sciences Unit, Centre for Reproductive Biology, The University of Edinburgh Academic Centre, Chancellor's Building, Edinburgh, Scotland EH16 4SB, United Kingdom.
authors.forename: Gabrielle B
authors.initials: GB
authors.lastname: Perchick
authors.forename: Henry N
authors.initials: HN
authors.lastname: Jabbour
mesh_terms: D043168:Angiostatins / Q000378:metabolism*; D002402:Cathepsin D / Q000378:metabolism*; D002460:Cell Line; D051546:Cyclooxygenase 2; D015232:Dinoprostone / Q000378:metabolism; D004717:Endometrium / Q000166:cytology; D004847:Epithelial Cells / Q000166:cytology / Q000502:physiology*; D005260:Female; D015971:Gene Expression Regulation, Enzymologic; D006801:Humans; D007527:Isoenzymes / Q000235:genetics*; D008565:Membrane Proteins; D009389:Neovascularization, Pathologic / Q000378:metabolism; D010958:Plasminogen / Q000378:metabolism*; D011451:Prostaglandin-Endoperoxide Synthases / Q000235:genetics*; D018078:Receptors, Prostaglandin E / Q000235:genetics; D015398:Signal Transduction / Q000502:physiology; D014162:Transfection
chemical_list: D007527:Isoenzymes; D008565:Membrane Proteins; D018078:Receptors, Prostaglandin E; D043168:Angiostatins; D010958:Plasminogen; D051546:Cyclooxygenase 2; C496540:PTGS2 protein, human; D011451:Prostaglandin-Endoperoxide Synthases; D002402:Cathepsin D; D015232:Dinoprostone