Overexpression of sense or antisense human gastrin mRNA does not affect proliferation of normal rat kidney fibroblasts

Progastrin-derived peptides have been reported to stimulate mitogenesis in Swiss 3T3 fibroblasts [P. Singh, A. Owlia, R. Espeijo, B. Dal, Novel gastri n receptors mediate mitogenic effects of gastrin and processing intermediat es of gastrin on Swiss 3T3 fibroblasts: Absence of detectable cholecystokin in (CCK)-A and CCK-B receptors. J. Biol. Chem. 270 (1995) 8429-5438]. The a im of the present study was to determine the generality of these findings, by investigating the effect of endogenous and exogenous progastrin-derived peptides on the proliferation of the normal rat kidney fibroblast cell line NRK. Levels of endogenous progastrin-derived peptides were modified by sta ble transfection of NRK cells with telracycline-repressible plasmids contai ning sequences encoding human gastrin in either the sense or antisense orie ntation. Expression of sense and antisense gastrin mRNA was demonstrated by reverse transcriptase PCR and by radioimmunoassay, and cell proliferation rates were determined by the colorimetric MTT assay. Sense clones produced full length human progastrin, but significant quantities of glycine-extende d or amidated gastrin(17) were not detected. Concentrations of endogenous r at progastrin in antisense clones were significantly lower than concentrati ons in clones transfected with vector only. However no difference in prolif eration rate was observed between sense, antisense and vector-transfected c lones. No stimulation of proliferation was observed in synchronised untrans fected NRK cells after supplementation of media with gastrin(17) or gastrin (17)gly in the concentration range 0.3 to 100 nM. Our results do not provid e evidence in support of the hypothesis that endogenous or exogenous progas trin-derived peptides act as growth factors in NRK fibroblasts. (C) 1999 El sevier Science Ltd. All rights reserved.