Long-Chain Non-Coding RNA Metastasis-Related Lung Adenocarcinoma Transcript 1 (MALAT1) Promotes the Proliferation and Migration of Human Pulmonary Artery Smooth Muscle Cells (hPASMCs) by Regulating the MicroRNA-503 (miR-503)/Toll-Like Receptor 4 (TLR4) Signal Axis

BACKGROUND: To study the role of the long-chain noncoding RNA (lncRNA) metastasis-related lung adenocarcinoma transcript 1 (MALAT1), microRNA-503 (miR-503), Toll-like receptor 4 (TLR4) signal axis in the pathogenesis of pulmonary arterial hypertension (PAH). MATERIAL/METHODS: Total RNA was extracted from the plasma of 45 PAH patients and 45 healthy subjects, and the expression of lncRNA MALAT1 and miR-503 was measured by quantitative real-time polymerase chain reaction (qRT-PCR). The effects of lncRNA MALAT1 and miR-503 on Toll-like receptor 4 (TLR4) and the proliferation, migration, and apoptosis of human pulmonary artery smooth muscle cells (hPASMCs) were tested following in vitro transfection of hPASMCs. RESULTS: lncRNA MALAT1 was highly expressed in the plasma of PAH patients and in hypoxia-induced hPASMCs. Silencing lncRNA MALAT1 inhibited the proliferation and migration of hPASMC cells while promoting their apoptosis. MiR-503 is underexpressed in plasma and hPASMCs of patients with PAH. TLR4 was a target gene of miR-503 and was highly expressed in peripheral blood mononuclear cells (PBMCs) of PAH patients. lncRNA MALAT1 was a “molecular sponge” of miR-503, regulating the expression of TLR4 and the proliferation, migration, and apoptosis of hPASMCs through miR-503. CONCLUSIONS: lncRNA MALAT1 promotes the proliferation and migration of hPASMCs and inhibits their apoptosis by inhibiting the miR-503/TLR4 signal axis.