The effects of siRNA against RPL22 on ET-1-induced proliferation of human pulmonary arterial smooth muscle cells.

The aim of this study was to investigate the effects of small interference RNA (siRNA) against ribosomal protein L22 (RPL22) on ET-1-induced proliferation of human pulmonary arterial smooth muscle cells (HPASMCs). HPASMCs were transfected with siRNA against RPL22, incubated in smooth muscle cell culture medium (SMCM) and ET-1. RPL22 gene expression and protein levels of HPASMCs were measured by real-time PCR and western blotting, respectively. PCNA, CCK-8 immunohistochemistry and flow cytometry analysis were used to evaluate HPASMC proliferation. Cyclin D1 (CCND1) expression was also assayed. Following transfection with siRNA against RPL22, RPL22 expression was significantly inhibited in the control and ET-1 groups. HPASMC proliferation was significantly suppressed by transfection with siRNA against RPL22. Moreover, CCND1 was also downregulated by inhibiting RPL22 expression. In conclusion, these data suggest that inhibition of RPL22 expression can suppress HPASMC proliferation and CCND1 expression. The effects of siRNA against RPL22 on HPASMC proliferation are considered to be mediated through inhibition of CCND1 expression.