ANTAGONIZING MIRNA TARGETING THE WNT PATHWAY TO TREAT PRIMARY AND SECONDARY OSTEOPOROSIS.

Osteoporosis is characterized by a progressive loss of bone mass determined by an alteration of the bone remodeling balance. The two most frequent forms of osteoporosis are represented by postmenopausal and glucocorticoid-induced osteoporosis (GIO). The Wnt/-catenin signaling pathway has emerged as a critical regulatory component of the control of bone metabolism, opening new possible avenues in the management of osteoporosis, since it is also regulated by miRNAs. The aim of this study is to identify those miRNAs involved in primary and secondary osteoporosis that interfering with the Wnt/-catenin pathway could represent therapeutic targets by using antagomirs. OVX and GIO mice were used as osteoporotic models. Mice osteoblasts were harvest to isolate mRNA, while miRNAs were obtained from culture media. Q-Real-Time PCR was performed on specific targets and miRNAs which are known to interfere with the Wnt signaling pathway in osteoporosis. In OVX mice, the analysis of miRNAs and mRNA profiles revealed a significant up-regulation of miR-199a-5p and miR-31-5p. In the GIO model, miR-9-5p and miR-141-3p in males, and let-7c-5p in females, were found up-regulated. These up-regulated microRNAs have also been shown to correlate with genes involved in the Wnt pathway as well as bone homeostasis. Therefore, the respective antagomirs were designed and assigned to treat the two experimental models, then femurs were harvest to isolate osteoblasts for molecular investigations, and to perform micro-CT and histological analysis. Q-PCR results revealed how treatment with antagomirs stimulated the expression of osteogenic markers in both OVX and GIO mice, supported by micro-CT and histological evaluations, which revealed that cortical and trabecular thickness, mineralization, porosity, as well as lesions and reduced cellularity found in OVX and GIO mice, were mitigated in animals treated with the assigned antagomirs. In conclusion, these data suggest that treatment with miR-31-5p and miR-199a-5p antagomirs in postmenopausal osteoporosis, and with miR-9-5p, miR-141-3p, and let-7c-5p antagomirs in GIO could be a valid anabolic therapeutic strategy.