Fluid Shear Stress and Raloxifene Stimulates the Proliferation of Osteoblast Through Regulating the Expresstion of β-catenin and Estrogen Receptor α

Objective To investigate how the fluid shear stress and raloxifene alone or in combination affect the proliferation of murine pre-osteoblast MC3T3-E1. Methods MC3T3-E1 cells cultured in vitro were treated with the fluid shearing stress and raloxifene alone or in combination, and the MC3T3-E1 cells without treatment were set as control (O group), treated with estrogen receptor antagonist ICI-182780 (10^-7 mol/L, I group) were set as negative control group．The cells were observed underoptical inverted microscope from cell shape, size, and nuclear shape to quantity respectively before harvested. The levels of mRNA and protein of β-catenin and estrogen receptor alpha (ERα) were detected by reverse transcription polymerase chain reaction (RT-PCR) and Western blot respectively. Results ① As compared with those of the control group and negative control group, the cell proliferation, the expression of ERα mRNA and protein, and protein expression of β-catenin significantly increased in the groups of raloxifene, fluid shearing stress and raloxifene combination fluid shearing stress (P<0.05). RT-PCR analysis showed that the levels of β-catenin mRNA though were not changed significantly in raloxifene group compared with O group (P>0.05), increased significantly in groups of fluid shear stress and raloxifene combination fluid shear stress. ② The cells number, the expression of β-catenin and ERα were not changed significantly between raloxifene group and fluid shearing stress group (P>0.05), but all test parameters in groups of raloxifene combination fluid shearing stress were higher than that of the previous two groups (P<0.05). Conclusion Fluid shear stress and raloxifene, the selective estrogen receptor modulator, were verifed to be able to promote MC3T3-E1 proliferation, increase the expression of β-catenin and ERα, and the combination functioned synergicly significantly. Fluid shear stress and raloxifene may possiblely affect the osteoblast proliferation by regulating the signaling pathways of Wnt/β-catenin and ER.