H-RAS controls phenotypic profiles of vascular smooth muscle cells and the pathogenesis of vascular proliferative disorders

Vascular smooth muscle cell proliferation as a therapeutic target. Part 1: molecular targets and pathways

Cardiovascular diseases are a major cause of human death worldwide. Excessive proliferation of vascular smooth muscle cells contributes to the etiology of such diseases, including atherosclerosis, restenosis, and pulmonary hypertension. The control of vascular cell proliferation is complex and encompasses interactions of many regulatory molecules and signaling pathways. Herein, we recapitulated the importance of signaling cascades relevant for the regulation of vascular cell proliferation. Detailed understanding of the mechanism underlying this process is essential for the identification of new lead compounds (e.g., natural products) for vascular therapies.

Ras ssDNA aptamer inhibits vascular smooth muscle cell proliferation and migration through MAPK and PI3K pathways

Proliferation and migration of vascular smooth muscle cells (VSMCs) mediated by Ras proteins are crucial in restenosis following percutaneous coronary intervention (PCI) and coronary artery bypass graft (CABG). In this study, a novel, single-stranded DNA (ssDNA) aptamer designated as Ras-a1 with high affinity and specificity to human Ras protein was isolated using systematic evolution of ligands by exponential enrichment. Ras-a1 was delivered into VSMCs by electroporation using one square waveform of 200 V for 20 msec. Proliferation of VSMCs was determined using a cell counting kit‑8 assay, which revealed the maximal inhibitory rate (40%) was obtained at 24 h after Ras-a1 transfection. The migration of VSMCs, determined using a Transwell assay, was significantly inhibited in Rasa1 cells in a time-dependent manner. To investigate the potential mechanisms of transfected Ras-a1 on the migration and proliferation of VSMCs, the phosphorylation of MEK1/2, ERK1/2, and Akt was determined using western blot analysis, which showed that a marked downregulation was observed in the phosphorylation of MEK1/2, ERK1/2, and Akt following the delivery of Ras-a1. This result demonstrated that Ras-a1 inhibits the proliferation and migration of VSMCs by inhibiting the phosphorylation of Ras and interrupting signal transduction in the Ras‑MEK1/2‑ERK1/2 and phosphoinositide-3 kinase/Akt pathways. The novel Ras protein-targeted ssDNA aptamer selected may be applicable for the prevention of restenosis after PCI and CABG.

Targeted genomic disruption of h-ras induces hypotension through a NO-cGMP-PKG pathway-dependent mechanism

The aim of the present experiments was to evaluate the differences in arterial pressure between H-Ras lacking mice and control mice and to analyze the mechanisms involved in the genesis of the differences. H-Ras lacking mice and mouse embryonic fibroblasts from these animals were used. Blood pressure was measured using 3 different methods: direct intraarterial measurement in anesthetized animals, tail-cuff sphygmomanometer, and radiotelemetry. H-Ras lacking mice showed lower blood pressure than control animals. Moreover, the aorta protein content of endothelial nitric oxide synthase, soluble guanylyl cyclase, and cyclic guanosine monophosphate-dependent protein kinase was higher in H-Ras knockout mice than in control animals. The activity of these enzymes was increased, because urinary nitrite excretion, sodium nitroprusside-stimulated vascular cyclic guanosine monophosphate synthesis, and phosphorylated vasoactive-stimulated phosphoprotein in aortic tissue increased in these animals. Furthermore, mouse embryonic fibroblasts from H-Ras lacking mice showed higher cyclic guanosine monophosphate-dependent protein kinase promoter activity than control cells. These results strongly support the upregulation of the nitric oxide-cyclic guanosine monophosphate pathway in H-Ras-deficient mice. Moreover, they suggest that H-Ras pathway could be considered as a therapeutic target for hypertension treatment.