Stimulation of in vitro angiogenesis by nitric oxide through the induction of transcription factor ETS-1

The aim of this study was to examine whether transcription factor ETS-1, which is responsible for the expression of metalloproteinases and integrin beta(3), is implicated in the induction of nitric oxide (NO)-induced angiogenesis. Bovine aortic endothelial cells were cultured on type I collagen gel to measure the length of the formed tube-like structure, which is a marker for in vitro angiogenesis. The addition of S-nitroso-N-acetylpenicillamine (SNAP), an NO-donor, to confluent endothelial cells stimulated the formation of the tube-like structure, with disappearance of covered endothelial cell monolayers. Another NO-donor 2,2'-(hydroxynitrosohydrazono)bis-ethanamine (NOC 18) also induced the formation of the tube-like structure. In contrast to the induction of the formation of the tube-like structure by SNAP, it reduced cell proliferation. SNAP and NOC 18 also increased the expression of the ets-1 mRNA level in a concentration-dependent manner. The maximum expression was observed at 2h after their addition. Moreover, the SNAP-induced in vitro angiogenesis, ets-1 mRNA expression and ETS-1 protein expression were strongly reduced by the treatment with ets-1 antisense oligonucleotide. These results strongly suggest that NO stimulates in vitro angiogenesis through the induction of ETS-1 expression. NO appears to stimulate endothelial cell differentiation to the angiogenic phenotype via the induction of ETS-1 transcription factor.