Effects of core-binding factor α1 gene silenced by siRNA on calcification of vascular smooth muscle cells induced by high phosphate

Abstract

To explore the effects of core-binding factor α1 (Cbfα-1) gene silenced by siRNA on osteogenic differentiation and calcification of vascular smooth muscle cells (VSMC) induced by high phosphate in vitro. VSMC were cultured in vitro and passaged 3 to 8 times. Four pairs of Cbfα-1 siRNA were designed and synthesized. Transfection was performed with cationic lipid vectors (Lipofectamine 2000). Transfection conditions were optimized by the FAM fluorescent labeling-siRNA to screen effective siRNA sequences by reverse transcription-polymerase chain reaction (RT-PCR). After transfection with effective siRNA sequences, VSMCs were divided into 4 groups: (1) normal phosphate (Pi 1.3 mmol/L); (2) high phosphate (Pi 2.6 mmol/L); (3) siRNA transfection: high phosphate+Cbfα-1-siRNA; (4) negative transfection control: high phosphate+negative control siRNA. Cbfα-1 and osteopontin (OPN) mRNA and protein expression were detected by RT-PCR and Western blotting. Calcium deposition was visualized by Alizarin stain method. The transfection efficiency was around 55% with a concentration of Cbfα-1 siRNA 100 nmol/L and Lipo 8 µl/ well. Cbfα-1 siRNA 1952 was chosen as the effective sequence with a suppression ratio up to 81.8%. At 24 and 48 h post-transfection, the expression of Cbfα-1 mRNA was significantly lower in siRNA transfection group than that in high phosphate group (0.335 ± 0.059 vs 0.714 ± 0.106, 0.574 ± 0.036 vs 0.726 ± 0.086, all P < 0.01) . At 48 and 72 h post-transfection, the expression of Cbfα-1 protein in siRNA transfection group was significantly lower than that in high phosphate group (both P < 0.01) . While Cbfα-1 gene was silenced by siRNA in siRNA transfection group, the mRNA and protein expression of OPN significantly declined (all P < 0.05) and calcium deposition in cell layers decreased. Cbfα-1 siRNA can effectively inhibit the expression of Cbfα-1 mRNA and protein in VSMC and thus suppress the transformation of VSMC into osteoblast-like cells and calcification induced by high phosphate. Cbfα-1 may become a potential therapeutic target in vascular calcification of chronic kidney disease.