MiR-146 a inhibits proliferation and induces apoptosis in murine osteoblastic MC 3 T 3E 1 by regulating Bcl 2

divided into traumatic ONFH and non-traumatic ONFH1. Non-traumatic hormone-induced necrosis of the femoral head is the most general one, mostly happened in young people2. The pathogenesis of steroid-induced femoral head necrosis is complex. The direct effect of hormones on ONFH is regulating the differentiation, proliferation and apoptosis of osteocytes, eventually leading to loss of bone mass, femoral head collapse3-5. The indirect effect of hormones on ONFH is leading to thrombosis generation by promoting the apoptosis of vascular endothelial cells, affecting the vasoconstriction and diastolic activity of the expression of substances and lipid metabolism by inhibiting the expression of vascular endothelial growth factor (VEGF) and making obstacle to the generation of neovascularization6. Clinical data shows that osteoblast apoptosis contributes the pathogenesis of hormone-induced femoral head necrosis, which is the cytological basis of necrosis of femoral head7,8. Since osteoblasts are the main functional cells of the femoral head, the abnormal proliferation and apoptosis of osteoblasts in the femoral head are the hotspots of the study of steroid-induced ONFH. Intensive bone cell apoptosis contributes to ONFH9. Bcl2 is an important anti-apoptotic member in Bcl2 family, which can enhance the resistance of cells to most DNA damage factors, inhibit cell apoptosis and necrosis10. Studies have shown that high doses hormone inhibit the expression of Bcl2 gene and promote osteocyte apoptosis11. Avascular necrosis and apoptosis were caused by variety factors in the destruction of bone cells, in which miRNA played an important regulatory role. In recent years, inAbstract. – OBJECTIVE: The dysregulation of proliferation and apoptosis plays a significant role in the pathogenesis of hormone-induced osteonecrosis of femoral head (ONFH). The research aimed to explore the regulatory role of miR-146a in dexamethasone (DEX)-induced proliferation and apoptosis change in MC3T3-E1 cells from murine osteoblastic. MATERIAL AND METHODS: In this study, MC3T3-E1 was co-cultured with 10-7 DEX for 6 h, then RT-PCR was employed to test the expression level of miR-146a and Bcl2. CCK8 assay and flow cytometry were adopted to verify miR-146a could regulate proliferation and apoptosis. After transfected MC3T3-E1 with mimics and inhibitor, RT-PCR and Western blot was used to detect Bcl2 expression level. RESULTS: In DEX treated MC3T3-E1 cells showed higher MiR-146a expression level and lower Bcl2 expression level. MiR-146a could inhibit proliferation and promotes apoptosis in murine osteoblastic MC3T3-E1 cells. Additionally, Bcl2 gene is regulated by MiR-146a. CONCLUSIONS: The MiR-146a expression level increased, while Bcl2 has low expression level in dexamethasone treated MC3T3-E1 cells. MiR-146a regulates proliferation and apoptosis of mouse bone cells. The low expression level of Bcl2 in DEX treated MC3T3-E1 cells is caused by increased MiR-146a level.