Endogenously generated nitric oxide by nitric-oxide synthase gene transferinhibits cellular proliferation

We investigated whether endothelial nitrite oxide synthase (NOS) gene trans fer inhibited cellular proliferation. Endothelial NOS and endothelin type A receptor genes were transferred into 293 cells, a human embryonic kidney c ell line, by calcium-phosphate coprecipitation. The cytosolic free Ca2+ lev els ([Ca2+](i)) of transfected cells were estimated with fura-2 fluorescenc e. Thymidine incorporation was increased by endothelin-1 in type A receptor -transfected cells. The endothelial NOS gene transfer did not affect endoth elin-1-induced increase in [Ca2+](i) of type A receptor-transfected cells, but markedly inhibited mitogen-activated protein kinase and c-fos promoter activities. The endothelial NOS gene transfer also inhibited thymidine inco rporation into type A receptor-transfected cells in response to endothelin- 1, which was abolished in the presence of the NOS inhibitor N-G-monomethyl- L-arginine acetate. The endothelin-1-induced increase in cell number was si gnificantly suppressed by endothelial NOS gene transfer as well as by the m itogen-activated protein kinase inhibitor PD98059. These results indicate t hat endothelial NOS gene transfer inhibits cellular proliferation via inhib ition of the mitogen-activated protein kinase cascade.