MicroRNA-199a Regulates Hypoxia-Mediated Pulmonary Artery Smooth Muscle Cell Proliferation and Migration by Targeting ROCK1

SESSION TITLE: Pulmonary Arterial Hypertension Posters I SESSION TYPE: Original Investigation Poster PRESENTED ON: Wednesday, October 28, 2015 at 01:30 PM - 02:30 PM PURPOSE: Pulmonary hypertension (PH) is a progressive devastating disease characterized by excessive proliferation and abnormal migration of the pulmonary arterial smooth muscle cells (PASMCs). Studies have shown that PH and cancer have the same pathophysiological process of excessive cell proliferation and migration. MicroRNA-199a (miR-199a) is known to regulate proliferation and migration and is implicated in various types of cancers. However, the role of miR-199a in PH has not been studied. In the present study, we hypothesized that miR-199a could play a role in the proliferation and migration of PASMCs. METHODS: The expression of miR-199a was analyzed by quantitative reverse transcription-PCR. The protein expression of PCNA, c-fos, c-jun, c-myc and caspase-3 was analyzed by western blot. The mimic and inhibitor of miR-199a were used in gain-of-function and loss-of-function in vitro studies, respectively. RESULTS: We first demonstrated that miR-199a was drastically downregulated by ~85% in rats PASMCs after 6 h of hypoxia (3% O2) and remained low (~15%) after 48 h of hypoxia. MiR-199a overexpression with has-miR-199a mimics significantly reduced hypoxia-induced cell proliferation and increased apoptosis, whereas knockdown of miR-199a with anti-miR-199a inhibitors enhanced cell proliferation and reduced apoptosis. We also found that miR-199a is essential for hypoxia-induced cell migration. Protein expression of PCNA, c-fos, c-jun and c-myc was increased in hypoxia and in PASMCs which miR-199a was knocked down in both normoxia and hypoxia, and decreased in PASMCs overexpressing miR-199a in both normoxia and hypoxia. Furthermore, miR-199a promoted caspase-3, ultimately leading to apoptosis of PASMCs. In addition, ROCK1-3'UTR-luciferase-based reporter gene assays demonstrated that ROCK1, which is key a factor in PH development, is a direct target of miR-199a. CONCLUSIONS: Taken together, our findings indicate that miR-199a plays a significant role in hypoxia-induced pulmonary vascular smooth muscle cell proliferation and migration by regulating ROCK1. CLINICAL IMPLICATIONS: Our findings indicate that miR-199a may play a significant role in hypoxia-induced pulmonary hypertension and miR-199a may be a new target for the treatment of pulmonary hypertension. DISCLOSURE: Xi-Qian Xing: Grant monies (from sources other than industry): National Natural Science Foundation of China (81100037, 81360049) The following authors have nothing to disclose: Jiao Yang, Xu-Wei Wu, Yan-Li Li, Yu-Xuan Zhang, Hong-Yan Zhang, Li-Qiong Liu, Yu-Shan Zhou, Yi Xiao, Zhi-Dong Li, Hong-Yan Liu No Product/Research Disclosure Information