title: Involvement of nitric oxide in tumor cell adhesion to cytokine-activated endothelial cells.
abstract: The aim of the present experiments was to test the possible involvement of nitric oxide (NO) in cytokine-induced enhancement of tumor cell (TC) adhesion to endothelial cells (ECs). Exposure of EA hyb 926 cells to TNF (500 U/ml) plus IFN (100 U/ml) for 24 h significantly enhanced their adhesivity for the 51Cr-labeled GLC1 (small cell lung carcinoma) TCs. Conversely, exposure of TCs to cytokines did not result in an increased adhesion of these cells to ECs. TC-stimulated adhesion to EA hyb 926 was abrogated by the glucocorticoid dexamethasone (Dex, 10(-7) M), the NO synthase inhibitors N omega-nitro-L-arginine methyl ester (L-NAME, 10(-5) M) and NG-monomethyl-L-arginine (L-NMMA, 10(-5) M) and the protein synthesis inhibitor cycloheximide (Cex, 10(-6) M). Furthermore, GLC1-stimulated adhesion to EA hyb 926 was reversed following removal of L-arginine from the medium or pretreatment with the guanylate cyclase inhibitor methylene blue. TC-stimulated adhesion was also prevented when TCs were pretreated with the monoclonal antibody CD15 directed against the endothelial-leukocyte adhesion molecule (ELAM-1) ligand or following exposure of ECs to anti-ELAM-1 monoclonal antibody. Although suppressing TC-stimulated adhesion, L-NMMA failed to modify significantly cytokine-induced ELAM-1 expression in EA hyb 926. These results (a) provide evidence for the NO-inducible pathway contributing to cytokine-induced enhancement of tumor cell adhesion to the vascular endothelium and (b) demonstrate the involvement of the ELAM-1/CD15 adhesion system in tumor cell-stimulated adhesion to ECs.
mesh_terms: D001120:Arginine / Q000031:analogs & derivatives / Q000494:pharmacology; D002448:Cell Adhesion / Q000187:drug effects; D015815:Cell Adhesion Molecules / Q000276:immunology / Q000502:physiology; D002460:Cell Line; D003513:Cycloheximide / Q000494:pharmacology; D016207:Cytokines / Q000494:pharmacology*; D003907:Dexamethasone / Q000494:pharmacology; D019040:E-Selectin; D004730:Endothelium, Vascular / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D006801:Humans; D008751:Methylene Blue / Q000494:pharmacology; D019331:NG-Nitroarginine Methyl Ester; D009569:Nitric Oxide / Q000378:metabolism*; D014407:Tumor Cells, Cultured / Q000187:drug effects / Q000502:physiology*; D019323:omega-N-Methylarginine
chemical_list: D015815:Cell Adhesion Molecules; D016207:Cytokines; D019040:E-Selectin; D019323:omega-N-Methylarginine; D009569:Nitric Oxide; D003907:Dexamethasone; D001120:Arginine; D003513:Cycloheximide; D008751:Methylene Blue; D019331:NG-Nitroarginine Methyl Ester