Expression of The Factors Associated With Wnt/β-Catenin, BMP-2/Runx2/Osterix, OPG/RANKL and LGR4/RANKL Pathways in Postmenopausal Osteoporosis Fracture

Abstract Objective Detect and analyse the correlation between factors of related pathways (Wnt/β-catenin, BMP-2/Runx2/Osterix, OPG/RANKL and LGR4/RANKL) and postmenopausal osteoporotic fracture (PMOPF). Methods The postmenopausal patients with tibial fracture were divided into control group (36 cases) and PMOPF group (36 cases). Using RNAiso Plus method to extract total RNA of bone tissue, RT-qPCR method was used to detect the expression of each factor. Detected the levels of serum of factors by ELISA method in control group. PMOPF group was divided into group A-F according to the blood collection time interval (at different time period), use ELISA method to detect each factor’s level. Compared the changes between control group and PMOPF group, and the subdivided groups of PMOPF group. Results (1) RT-qPCR detected the expressions of LRP5, β-catenin, Runx2, C-myc, Osterix, OPG and LGR4 in PMOPF group were lower than control group (P<0.05), but the expression of RANKL was increased (P<0.05). (2) ELISA detected the serum levels of LRP5, β-catenin, Runx2, C-myc, Osterix, OPG and LGR4 decreased significantly (P<0.05), and RANKL increased significantly (P<0.05). LRP5 and Runx2 appeared the lowest in Group B (2-3 days after fracture); β-catenin and C-myc appeared the lowest in Group C (4-7 days after fracture); RANKL appeared the highest in Group C; Osterix appeared the lowest in Group D (8-14 days after fracture); OPG and LGR4 appeared the lowest in Group E (15-28 days after fracture). Conclusion The related factors of Wnt/β-catenin, BMP-2/Runx2/Osterix, OPG/RANKL and LGR4/RANKL pathway are closely related to the occurrence of PMOPF. LRP5 and Runx2 decreased to the lowest level within 3 days after fracture, β-catenin and C-myc decreased to the lowest level within 7 days after fracture, the results showed that these changes in Wnt/β-catenin osteogenesis pathway were consistent; Osterix decreased to the lowest level within 14 days after fracture, OPG and LGR4 decreased to the lowest level within 28 days after fracture, which may be related to the difficulty of short-term healing of PMOPF; RANKL increased to the highest level within 7 days after fracture, which may be associated with the increase in bone formation after PMOPF. According to the changes and characteristics of these factors in above pathways, we can regulate or intervene the occurrence and progression of PMOPF.