“Cytotoxicity of Dup 753 in Macrophages Evaluate by Different Endpoints”

Abstract

We have recently established and characterized a new conditionally immortalized mouse gastric epithelial cell line . The purpose of this work was to compare the effects of amidated (G-NH2) and glycine-extended gastrin (G-gly) on proliferation and migration of these cells. Both G-NH2 and G-gly strongly stimulated DNA synthesis, although with slightly different potencies (EC50 = 22.8 ? 1.5 pM for G-gly and 84.3 ? 2.9 pM for G-NH2). The G-NH2 effect was dose-dependently reversed by the selective gastrin/CCK-B receptor antagonist L365,260 but not by the selective CCK-A receptor antagonist, L364,718. Neither antagonist inhibited G-gly-stimulated DNA synthesis. In contrast two selective inhibitors of phosphatidylinositol-3 kinase (PI-3K) reversed Ggly-induced proliferation, but did not affect stimulation by G-NH2. In parallel to the studies on proliferation, we also evaluated the role of both gastrins in a wound repair model. G-NH2 did not stimulate healing, but G-gly was found to induce wound repair, although with a weaker potency than that observed for the proliferative effect. The stimulatory effect of G-gly on healing was also PI-3K dependent. Our results indicate the potential of IMGE-5 cells as a model in which to study the effects of gastrin on epithelial cell differentiation, and argue in favor of distinct roles for glycine-extended and amidated gastrins in the stomach. "CYTOTOXICITY OF DUP 753 IN MACROPHAGES 012 EVALUATE BY DIFFERENT ENDPOINTS" ~. " ; Melo, f).S.'; Ham, M.'; pelhsnq F.B.'; Wp, J.A2 and Figucimb, J.F.' F . Bbquhb, zDkiplina de Nchbgia e NWa, dCIb4CdeChgkl--U N I C A M P -C k l @ t d S Ikari. Angiotensins arc peptidea, which are produced in diffamt organs and get the circulation to target specific receptors to trigger several responses. Reant investigations have shown that Angiotensin II (An) can be able to stimulate peroxide production of macrophages through AT1 reaptor (YanagitaN et al., 1999). To check this hypothesis mice peritoneal macrophsges were kept in WMt d i u m complrmentced with loo/o fed bovine serum at 37OC in a humidifid, 5% C Q atmosphere for 48 h. In these conditions wc determined during 1 and 3 h the dose-depedent curve of AII and DUP 753 to verify if this action could be mediated by ATI nceptor. The phagocytic index was determined by counting the paoentage of ingested particles and multiplying by the avenge number of particles per macr~p@e. The cell viability was measure by three different endpoints: LDH released,MTT reduction and nucleic content against a control group. Our muhs showed that the best w -'on of An for stimulate phagocytic activity was 1W" M and for DUP 753 the higher inhibitionwasobtaiwdwith 104Min 1 hand 1O6@1@Min3 h @<0,05). These results demonstrated that the. inhibition is not cquimolar. Other possibility for this block was the drug toxiCi, which could change the phagocyte activity, but in all assays DUP 753 did not showed toxic effects on macrophage cells evaluated by viability assays. By this way, the inhibition of phagocytic activity was due only by the...