miR-155-5p regulates mesenchymal stem cell osteogenesis and proliferation by targeting GSK3B in steroid-associated osteonecrosis.

microRNAs (miRNAs) have recently been recognized as playing an important role in bone-associated diseases. This study investigated whether the reduced miR-155-5p in steroid-associated osteonecrosis of the femoral head (ONFH) attenuated osteogenic differentiation and cell proliferation by targeting GSK3B. Bone marrow was collected from the proximal femurs of patients with steroid-associated ONFH (n = 10) and patients with new femoral neck fracture (n = 10) and mesenchymal stem cells (MSCs) were isolated. The expression profile, the biological function of miR-155-5p, and the interaction between miR-155-5p and GSK3B were investigated by cell viability measurement, western blot, real-time polymerase chain reaction, luciferase reporter assay, and Alizarin Red S (ARS) staining of MSCs. The MSCs that were obtained from the femoral neck fracture group and from the steroid-associated ONFH group were transfected with or without miR-155-5p. We found that, in ONFH samples, the level of mature miR-155-5p was significantly lower than that of control samples. By inhibiting GSK3B, miR-155-5p promoted the nuclear translocation of β-catenin, increased the expression of osteogenesis-related genes, and facilitated the proliferation and differentiation of MSCs. Restoring the expression of GSK3B in MSCs partially reversed the effect of miR-155-5p. These findings suggest that reduced miR-155-5p in steroid-associated ONFH attenuates osteogenic differentiation and cell proliferation by increased levels of GSK3B and inhibition of Wnt signaling.