Involvement of a transforming-growth-factor-beta-like molecule in tumor-cell-derived inhibition of nitric-oxide synthesis in cerebral endothelial cells.
Nitric oxide (NO) has been shown to exert cytotoxic effects on tumor cells. We have reported that EC219 cells, a rat-brain-microvessel-derived endothelial cell line, produced NO through cytokine-inducible NO synthase (iNOS), the induction of which was significantly decreased by (a) soluble factor(s) secreted by DHD/PROb, an invasive sub-clone of a rat colon-carcinoma cell line. In this study, the DHD/PROb cell-derived NO-inhibitory factor was characterized. Northern-blot analysis demonstrated that the induction of iNOS mRNA in cytokine-activated EC219 cells was decreased by PROb-cell-conditioned medium. When DHD/PROb cell supernatant was fractionated by affinity chromatography using Con A-Sepharose or heparin-Sepharose, the NO-inhibitory activity was found only in Con A-unbound or heparin-unbound fractions, respectively, indicating that the PROb-derived inhibitory factor was likely to be a non-glycosylated and non-heparin-binding molecule. Pre-incubation of DHD/PROb-cell supernatant with anti-TGF-beta neutralizing antibody completely blocked the DHD/PROb-derived inhibition of NO production by EC219 cells. Addition of exogenous TGF-beta 1 dose-dependently inhibited NO release by EC219 cells. The presence of active TGF-beta in the DHD/PROb cell supernatant was demonstrated using a growth-inhibition assay. Moreover, heat treatment of medium conditioned by the less invasive DHD/REGb cells, which constitutively secreted very low levels of active TGF-beta, increased both TGF-beta activity and the ability to inhibit NO production in EC219 cells. Thus, DHD/PROb colon-carcinoma cells inhibited NO production in EC219 cells by secreting a factor identical or very similar to TGF-beta.
Murata
J
J
Division of Neuropathology, Institute of Pathology, University of Lausanne, Switzerland.
Corradin
S B
SB
Felley-Bosco
E
E
Juillerat-Jeanneret
L
L
D000818:Animals; D001921:Brain / Q000098:blood supply*; D002450:Cell Communication / Q000502:physiology; D002460:Cell Line; D003110:Colonic Neoplasms / Q000378:metabolism* / Q000473:pathology; D016207:Cytokines / Q000378:metabolism / Q000502:physiology; D004730:Endothelium, Vascular / Q000166:cytology / Q000378:metabolism*; D004790:Enzyme Induction; D007371:Interferon-gamma / Q000494:pharmacology; D051379:Mice; D008833:Microcirculation; D009569:Nitric Oxide / Q000096:biosynthesis* / Q000502:physiology; D019001:Nitric Oxide Synthase / Q000096:biosynthesis / Q000378:metabolism; D051381:Rats; D011994:Recombinant Proteins; D013268:Stimulation, Chemical; D016212:Transforming Growth Factor beta / Q000378:metabolism / Q000502:physiology*; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology
D016207:Cytokines; D011994:Recombinant Proteins; D016212:Transforming Growth Factor beta; D014409:Tumor Necrosis Factor-alpha; D009569:Nitric Oxide; D007371:Interferon-gamma; D019001:Nitric Oxide Synthase