Sodium Butyrate Inhibits PDGFBB-Induced Proliferation And Migration In Pulmonary Artery Smooth Muscle Cells By Blocking AKT Activation

Abstract

IntroductionPulmonary arterial hypertension (PAH) is defined as a group of diseases caused by an increased pulmonary vascular resistance and subsequent right ventricular failure. This syndrome is characterized by abnormalities of pulmonary vascular biology in each compartment of the blood vessel. Vascular remodeling involves multiple signaling cascades regulating pulmonary arterial smooth muscle cells (PASMCs) proliferation, migration and differentiation. Sodium is a small butyrate histone deacetylase inhibitor affecting cell growth and differentiation. However, its effect on PASMCs had not been fully elucidated. Methods PASMCs were obtained from pulmonary artery of Wistar rats treated with a single dose of monocrotaline (MCT) in order to induce PAH. Cells were cultured in DMEM 10% FBS. PASMCs were starved in DMEM 0.5% FBS for 24 hours and treated with PDGF-BB 20ng/ml and Butyrate 5mM. Cell number was assessed indirectly by staining with dye crystal violet and proliferation was measured by uptake assay. For cell H3 thyimidine analysis, cells were stained with propidium iodide and analyzed by flow cytometry. We used a standard wound healing assay and a rat cycle pulmonary artery ring assay to evaluate cellular migration. Cells were collected for protein or RNA extraction and Western blot and Real Time PCR were performed. Cells cultured on glass coverslips were stained for assay. immunofluorescence Results Sodium butyrate significantly inhibited proliferation, DNA synthesis and migration of PDGF-BB-stimulated PASMC through inactivation of Akt without inducing cell death. Treatment with butyrate reduces the expression and the activation of PDGFR. At the same time butyrate induces cell-cycle arrest in the G(0)/G(1) phase associated with down-regulation of c-Myc, PCNA and cyclin D1, in addition to up-regulation of p21 and p15 at gene and protein level. We have also observed a down regulation of both and receptors for endothelin1, well-known target in PAH therapy. Conclusions Proliferation and migration of PASMCs is the hallmark of PAH, leading to hypertrophy of the medial smooth muscle layers in pre-capillary arterioles. Due to its proliferative and promigratory effects PDGF-BB gives a fundamental contribute to the development and progression of vascular remodeling in all types of pulmonary arterial hypertension. Butyrate has shown to be be effective in reducing PDGF-BB induced proliferation and migration in PASMCs. Moreover is able to reduce PASMCs responsiveness to endotelin1.