Cortistatin ameliorates Ang II-induced proliferation of vascular smooth muscle cells by inhibiting autophagy through SSTR3 and SSTR5

Aims: Vascular smooth muscle cell (VSMC) proliferation plays a significant role in the development of various vascular disorders. However, the effect of cortistatin (CST) on VSMC proliferation remains unclear. Therefore, the purpose of our research aimed to study whether CST protected VSMCs from angiotensin II (Ang II)-induced proliferation and which mechanisms participated in the process. Main methods: Cultured rat VSMCs were treated with Ang II with or without CST for 24 h. Cell proliferation rate was measured by cell counting kit-8 (CCK8) assay. The expressions of CST and its receptors were assessed by quantitative real-time PCR (qRT-PCR). The protein expression levels were analyzed by western blots. Immunofluorescence and transmission electron microscopy (TEM) were used to observe autophagy. Key findings: Our results showed that different concentrations of CST alleviated the Ang II-induced VSMC proliferation. The autophagy and reactive oxygen species (ROS) stimulated by Ang II were attenuated by CST. Furthermore, when the autophagy inhibitor 3-methyladenine (3-MA) was added, it exerted similar inhibition effects like CST, but didn't augment the protective role of CST on Ang II-induced VSMC autophagy and proliferation. Moreover, blocking somatostatin receptor 3 and 5 (SSTR3 and SSTR5) partially abrogated the suppressive effect of CST on Ang II-stimulated VSMC proliferation and autophagy. Significance: This study indicated that CST could ameliorate Ang II-stimulated VSMC proliferation by inhibiting autophagy partially through its receptors SSTR3 and SSTR5, providing a reasonable evidence for CST as a novel perspective therapeutic target of vascular diseases.