title: Nitric oxide modulates caveolin-1 and matrix metalloproteinase-9 expression and distribution at the endothelial cell/tumor cell interface.
abstract: We used a two-compartment coculture model comprising human endothelial cells (EC) and non-small cell lung carcinoma (CA) cells to study capillary formation. Elevated NO concentrations, contributed in part by CA cells, lead to inhibited capillary formation (Phillips PG, Birnby LM, Narendran A, and Milonovich WL. Am J Physiol Lung Cell Mol Physiol 281: L278-L290, 2001). Here we demonstrate using gelatin substrate zymography that high NO concentrations, whether produced endogenously or by NO donor spermine-NONOate or peroxynitrite-generating compound SIN-1, significantly inhibit MMP-9 expression and activation. Furthermore, high NO concentrations decrease Cav-1 abundance and alter its cellular distribution in EC. Cav-1 is essential for capillary formation in this model because Cav-1 antisense treatments targeted to EC significantly inhibit capillary formation. Laser confocal microscopy demonstrated extensive colocalization of MMP-9 with Cav-1 in sprouting EC, primarily at the basolateral surfaces of EC in focal structures associated with directed migration. This codistribution was NO concentration dependent, and elevated NO concentrations lead to marked dissociation of these two proteins. We propose that compartmentalization of MMP-9 within caveolar structures does occur, and that this could facilitate directed proteolysis essential for early migratory and invasive processes. Our data suggest elevated NO concentrations could impact on capillary formation via a combination of direct effects on MMP activation and by altering the distribution or abundance of Cav-1. Consequences of Cav-1 alterations may include impaired activation of proteolytic enzymes that utilize caveolar structure for stabilization and/or compartmentalization of MMP-9 as well as other putative members of an ECM proteolytic cascade.
authors.affiliation: Research Service, Samuel S. Stratton VA Medical Center, 113 Holland Ave., Albany, NY 12208, USA. Patricia.Phillips3@med.va.gov
authors.forename: Patricia G
authors.initials: PG
authors.lastname: Phillips
authors.forename: Linda M
authors.initials: LM
authors.lastname: Birnby
mesh_terms: D002196:Capillaries / Q000187:drug effects / Q000201:enzymology / Q000503:physiopathology; D002289:Carcinoma, Non-Small-Cell Lung / Q000098:blood supply; D051242:Caveolin 1; D022461:Caveolins / Q000235:genetics* / Q000378:metabolism; D045744:Cell Line, Tumor; D002478:Cells, Cultured; D004730:Endothelium, Vascular / Q000187:drug effects / Q000502:physiology* / Q000503:physiopathology; D004789:Enzyme Activation; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects*; D006801:Humans; D008175:Lung Neoplasms / Q000098:blood supply; D020780:Matrix Metalloproteinase 9 / Q000235:genetics* / Q000378:metabolism; D009569:Nitric Oxide / Q000494:pharmacology*; D020030:Nitric Oxide Donors / Q000494:pharmacology*; D014471:Umbilical Veins
chemical_list: C495540:CAV1 protein, human; D051242:Caveolin 1; D022461:Caveolins; D020030:Nitric Oxide Donors; D009569:Nitric Oxide; D020780:Matrix Metalloproteinase 9