Discovering Blood Circulating and Bone Micrornas as Biomarker Signatures for Diagnosis or Therapy of Osteoporosis in Men and Male Osteoporotic Fracture

Osteoporosis is one of the ten most common diseases worldwide. Bone fracture is typically linked to osteoporosis. In the past, osteoporosis is usually viewed as a woman disease. Recent studies showed that men and women lose their bone mass at the same rate after 65 of age. Furthermore, osteoporosis in men can cause higher risks of bone fracture and mortality. Thus, osteoporosis in men has recently aroused public attentions. Osteoporosis processes without pain and symptom till bone fracture occurs. As a result, developing significant biomarkers for diagnosis of osteoporosis and osteoporotic fracture is needed. MicroRNAs (miRNAs), non-coding small RNAs, participate in regulating biological activities by postranslationally targeting certain gene expressions. Osteoblasts and osteoclasts contribute to maintenance of bone structure. Functionally, miRNAs can regulate osteogenesis and osteoclastogenesis. Particularly, miRNAs are more stable and can be detected in blood as biomarkers for certain diseases. Our previous study has shown that circulating miR-106b was upregulated during tumor development. In postmenopausal women, various circulating miRNAs have been reported as potential biomarkers for osteoporosis and osteoporotic fracture. However, roles of miRNAs in osteoporosis in men are still unknown. Our preliminary results showed that circulating miR-133a was upregulated in male osteoporotic rats (Figs. 6 and 7). Moreover, expression of bone miR-1 was positively associated with fracture healing (Fig. 8). Thus, specific circulating and bone miRNAs may act as biomarkers or target effectors for osteoporosis in men and male osteoporotic fracture. Thus, this study is aimed to discover specific circulating and bone miRNAs as biomarker signatures for diagnostic or therapeutic purposes for osteoporosis in men (1st year) and male osteoporotic fracture (2nd year) as well as the molecular mechanisms about how these specific miRNAs can regulate osteogenesis and osteoclastogenesis by targeting certain gene expressions (3rd year) (Fig. 1). In the 1st year, this study will build up orchiectomy rats as our experimental model to mimic aging osteoporosis. Moreover, in the 2nd year, we will create femur fracture in orchiectomy rats to be our animal model of male osteoporotic fracture. This study will confirm osteoporosis occurrence and fracture healing by measurement of serum testosterone and analyses of bone mass using micro-computed topography (μCT). In addition, we will use next generation small RNA sequencing technology to screen specific circulating miRNAs in the blood and bone tissues. These specific miRNAs are further confirmed by real-time PCR and evaluated using bioinformatic approaches to verify their potentials as significant biomarkers for osteoporosis in men and male osteoporotic fracture. In the 3rd year, this project will isolate circulating monocytes (osteoclast precursors) and osteoblasts from the blood and the bone to investigate how these specific miRNAs can regulate osteogenesis and osteoclastogenesis. This study is expected to elucidate the roles of circulating and bone miRNAs in male osteoporosis and male osteoporotic fracture. Our results will be helpful for our upcoming clinical trials and establishment of new diagnostic and therapeutic strategies for osteoporosis-related disease in men.