Proteomic Analysis Of The Effect Of Iptakalim On Human Pulmonary Arterial Smooth Muscle Cell Proliferation

Hypoxic pulmonary hypertension (HPH) has been demonstrated to be an important physiopathologic event in the process of chronic obstructive pulmonary disease (COPD) to chronic cor pulmonale. Proliferation of pulmonary arterial smooth muscle cells (PASMCs) is a key feature during the development of hypoxia pulmonary hypertension (PH). Endothelin-1 (ET-1) has been implicated in the development of the pulmonary hypertension by remodeling of pulmonary vessels. The vascular remodeling associated with chronic hypoxia is likely mediated by the mitogenic effects of ET-1 on vascular smooth muscle cells (SMCs) resulting in their growth.Dysfunction of the potassium channels in the plasma membrane plays a pivotal role in PASMCs proliferation. Changes in K+ channel function may represent a universal mechanism by which Ca2+ signals are targeted towards activation of gene expression and cell growth. Furthermore, activation of K+ channels can induce apoptosis in vascular SMCs. Recently KATP channels have received intense scrutiny because of their biophysical properties, regulation and pharmacology. It has prompted a widespread interest in KATP channels as potential targets to regulate proliferative vascular disorders in disease conditions such as PH. Iptakalim(Ipt) is a lipophilic para-amino compound with low molecular weight, and has been demonstrated to be a newly selective KATP channel opener by pharmacological, electrophysiological and biochemical studies, and receptor binding test. Our previous study found that Iptakalim could alleviate pulmonary artery remodeling and has the therapeutic potential for the treatment of pulmonary arterial disorders in PH. Moreover, Iptakalim could inhibit the release and synthesis of ET-1 in cultured endothelial cells, and suppress the proliferation of rabbit/human ET-1-induced PASMCs in a concentration-dependent manner in vitro, with 10-5 M Iptakalim abolishing the effect of 10-8 M ET-1. However, the molecular mechanisms of its anti-proliferation effect remain poorly understood. In this study, a proteomic approach is used to investigate the anti-proliferation effect of Iptakalim in ET-1-induced human PASMCs. The results showed that 27 proteins whose expressions were induced or suppressed in ET-1-treated cells compared with control group and suppressed or induced in ET-1+Iptakalim-treated cells (compared with ET-1-treated group) were positively identified. Different functional groups of protein were regulated by Iptakalim in ET-1-induced human PASMCs, including cytoskeleton-associated proteins (actin, Vimentin, Lamin A/C, Tubulin), plasma membrane protein and receptors (annexin A5, G protein subunit beta 1, nucleoporin P54, Transmembrane channel-like protein 5), chaperon proteins (Hsp60, GRP 78, T-complex protein), ion transport-associated protein (Lasp-1), as well as metabolism associated proteins (Purine nucleoside phosphorylase, PGAM1 protein, Pgk1, et al ).