Effects of TGF-β1 on OPG/RANKL Expression of Cementoblasts and Osteoblasts Are Similar without Stress but Different with Mechanical Compressive Stress

INTRODUCTION This study aimed to explore the effects of TGF-β1 on regulating activities of cementoblasts and osteoblasts with or without stress. MATERIAL AND METHODS Human recombinant TGF-β1 was added with different doses. Immunohistochemical test of osteoprotegerin (OPG)/receptor activator of nuclear factor-kappaB ligand (RANKL) and Alizarin Red-S staining were conducted. Mechanical compressive stress was obtained by increasing the pressure of gaseous phase. OPG/RANKL expression was detected in both cells through quantitative real-time PCR. RESULTS Similar significant differences (P < 0.05) existed in OPG/RANKL change with increasing concentration of TGF-β1 without mechanical stress for cementoblasts and osteoblasts. However, under 3 h stress, OPG increased and RANKL decreased significantly (P < 0.01) but with similar OPG/RANKL change. Moreover, under 24 h stress, OPG change exhibited no difference (P > 0.05), but RANKL decreased significantly (P < 0.01) at 10 and 100 ng/mL TGF-β1 in cementoblasts. In osteoblasts, OPG increased significantly (P < 0.01) at 10 and 100 ng/mL, whereas RANKL decreased with statistical difference (P < 0.05) at 1 and 10 ng/mL. CONCLUSIONS The effects of TGF-β1 on OPG/RANKL expression of cementoblasts and osteoblasts are similar even without mechanical stress. However, these effects are different under mechanical compressive stress.