Schisandrin B inhibits the proliferation of airway smooth muscle cells via microRNA-135a suppressing the expression of transient receptor potential channel 1.

Airway smooth muscle cell (ASMC) was known to involve in the pathophysiology of asthma. Schisandrin B was reported to have anti-asthmatic effects in a murine asthma model. However, the molecular mechanism involving in the effect of Schisandrin B on ASMCs remains poorly understood. Sprague-Dawley rats were divided into three groups: rats as the control (Group 1), sensitized rats (Group 2), sensitized rats and intragastric-administrated Schisandrin B (Group 3). The expression of miR-135a and TRPC1 was detected in the rats from three groups. Platelet-derived growth factor (PDGF)-BB was used to induce the proliferation of isolated ASMCs, and the expression of miR-135a and TRPC1 was detected in PDGF-BB-treated ASMCs. Cell viability was examined in ASMCs transfected with miR-135a inhibitor or si-TRPC1. The expression of TRPC1 was examined in A10 cells pretreated with miR-135a inhibitor or miR-135a mimic. In this study, we found that Schisandrin B attenuated the inspiratory and expiratory resistances in sensitized rats. Schisandrin B upregulated the mRNA level of miR-135a and decreased the expression of TRPC1 in sensitized rats. In addition, Schisandrin B reversed the expression of miR-135a and TRPC1 in PDGF-BB-induced ASMCs. Si-TRPC1 abrogated the increasing proliferation of ASMCs induced by miR-135a inhibitor. We also found that miR-135a regulated the expression of TRPC1 in the A10 cells. These results demonstrate that Schisandrin B inhibits the proliferation of ASMCs via miR-135a suppressing the expression of TRPC1.