Rutaecarpine Suppresses Proliferation and Promotes Apoptosis of Human Pulmonary Artery Smooth Muscle Cells in Hypoxia Possibly Through HIF-1α–Dependent Pathways

Purpose The aim of this study is to investigate the potential roles of Rutaecarpine (Rut) in hypoxia-induced human pulmonary artery smooth muscle cells (HPASMCs) model. Methods HPASMCs were cultured with or without hypoxia followed by Rut administration. Cytotoxicity and cell proliferation were assessed by CCK-8 and Cell counting method. Flow cytometry was used for the measurement of cell apoptosis rates. The mRNA expression of hypoxia-induced factor (HIF)-1α and protein levels of HIF-1α, p53, p21, erythropoietin, and vascular endothelial growth factor were determined by quantitative real-time polymerase chain reaction and Western blot, respectively. Results Rut inhibited the proliferation of HPASMCs with IC50 value of 43.5 μmol·L. Hypoxia significantly increased proliferation and decreased apoptosis in HPASMCs, whereas Rut rescued this phenomenon at the appropriate concentration. Meanwhile, Rut effectively decreased the protein and mRNA expressions of HIF-1α. Knockdown of HIF-1α expression by small interfering RNA (siRNA) significantly enhanced the proapoptotic effect rather than antiproliferation effect of Rut in HPASMCs. Moreover, Rut simultaneously reduced proliferating cell nuclear antigen protein expression, whereas increased p53 and p21 protein levels. However, no significant difference was observed in the protein levels of vascular endothelial growth factor and erythropoietin. Conclusions Our results demonstrated that Rut exerted protective effects on HPASMCs against hypoxia partly through the HIF-1α-dependent signaling pathway.