Transforming growth factor-beta1 upregulation triggers pulmonary artery smooth muscle cell proliferation and apoptosis imbalance in rats with hypoxic pulmonary hypertension via the PTEN/AKT pathways

Transforming growth factor-betal (TGF beta 1) and Phosphatase and Tensin homolog deleted on chromosome ten (PTEN) are involved in the regulation of proliferation, differentiation, migration and apoptosis of various cell types. In previous studies, we have shown that TGF beta 1 and PTEN play an important role in the progression of pulmonary vascular remodeling induced by pulmonary artery smooth muscle cells (PASMCs). However, the mechanisms involved in the activation of PASMCs between TGF beta 1 and PTEN pathways remain unknown. We found that pulmonary vascular walls in hypoxic pulmonary arterial hypertension (PAH) rats were thicker than the vessels from normal rats in vivo. Substantially higher levels of TGF beta 1 and significant loss of PTEN expression were observed in the lungs of PAH rats when compared with normoxia. Meanwhile, AU, a downstream proliferative signaling protein of the PTEN antagonist PI3K, was markedly activated in the lungs of PAH rats. In vitro studies using PASMCs showed that TGF beta 1 increased cell proliferation in PTEN-dependent manner. Moreover, we found that TGF beta 1 enhanced cell survival, up-regulated the expression of Bcl-2 and procaspase-3, decreased the number of TUNEL-positive cells and caspase-3 expression in PASMCs under serum-deprived (SD) condition via PI3K/AKT pathway. The results further establish that TGF beta 1 promoted PAH by decreasing PTEN expression and increasing PI3K/AKT activation in the lung. In conclusion, TGF beta 1 mediated PTEN inactivation and resistance to apoptosis seems to be key mediators of lung vascular remodeling associated with PAH. These findings further clarify molecular mechanisms that support targeting PTEN/AKT signaling pathway to attenuate pathogenic derangements in PAH. (C) 2016 Elsevier Ltd. All rights reserved.