Epigenetic changes of RUNX2 and DLX5 genes in osteoblastic differentiation induced by zoledronic acid in mesenchymal stem cells

Zoledronic acid as a main treatment for osteoporosis has an important role in differentiation of mesenchymal stem cells. However, mechanism of osteoblastic differentiation induction by zoledronic acid is not well understood until now. In this research we evaluate zoledronic acid effect on methylation status of RUNX2 and DLX5 promoters. After isolation and expansion of hMSCs from BM, they were pulse treated with 5μM ZA for 3h, and incubated in osteogenic differentiation medium for 3 weeks. DNA was extracted after first, second and third weeks of culture and also from undifferentiated MSCs. After SBS treatment, gene specific methylation analysis for RUNX2 and DLX5 were carried out by MSP using methylated and unmethylated primers. In the genes RUNX2 and DLX5, M and U primers of MSP amplified promoter regions of undifferentiated and osteoblastic differentiated MSCs. Therefore, methylation status in RUNX2 and DLX5 promoters present incomplete methylation. Methyltion patterns of RUNX2 and DLX5 don’t change during zoledronic acid osteoblastic differentiation of MSCs. Our findings show that zoledronic acid does not induce osteoblastic differentiation via epigenetic mechanisms. Therefore, zoledronic acid can induce osteoblastic differentiation in a manner independent from DNA epigenetic changes.