Abnormal expression of miR‑135b‑5p in bone tissue of patients with osteoporosis and its role and mechanism in osteoporosis progression

Abstract

Osteoporosis (OP) is an age-related bone disease occurring worldwide. Osteoporotic fracture is one of the leading causes of disability and death in elderly patients. MicroRNAs (miRNAs/miRs) are key molecular regulatory factors in bone remodeling processes. The present study investigated the expression and mechanism of miR-135b-5p in patients with osteoporosis. The present results suggested that miR-135b-5p was upregulated in bone tissue fragments of patients with osteoporosis compared with the control patients. MC3T3-E1 cells were used to perform osteogenic differentiation induction. Reverse transcription-quantitative PCR and western blot assay were used to detect the mRNA and protein expression levels of the osteogenic markers osteocalcin (OC), Osterix and alkaline phosphatase (ALP). A specific kit was used for detecting ALP activity. The present results indicated that the mRNA expression levels of OC, Osterix and ALP significantly increased on the 7 and 14th day after osteogenic differentiation induction compared with the control group. Protein expression levels of OC, Osterix and ALP also increased on the 7 and 14th day after induction. ALP assay showed that ALP activity was significantly increased on the 7 and 14th day after induction. In addition, the present study found that miR-135b-5p was downregulated in MC3T3-E1 cells 7 and 14 days after osteogenic differentiation induction. The results of TargetScan analysis and dual luciferase reporter gene assay indicated that runt-related transcription factor 2 (RUNX2) was a direct target gene of miR-135b-5p. RUNX2 was upregulated in MC3T3-E1 cells on the 7 and 14th day after induction. Moreover, the present study found that compared with the osteogenic differentiation induction group, miR-135b-5p mimic significantly decreased OC, Osterix and ALP expression, and reduced ALP activity in MC3T3-E1 cells. However, these reductions were reversed following overexpression of RUNX2. The present results showed that miR-135b-5p mimic significantly reduced cell viability in MC3T3-E1 cells and induced cell apoptosis, and these effects were significantly reversed following RUNX2 overexpression. In summary, the present results suggested that miR-135-5p participated in the occurrence and development of osteoporosis via inhibition of osteogenic differentiation and osteoblast growth by targeting RUNX2. The present study suggested a novel potential target that may faciliate the treatment of osteoporosis, and further study is required to examine this possibility.

Identification of Potential Osteoporosis miRNA Biomarkers Using Bioinformatics Approaches

“…The result showed that 13 miRNAs were remarkably highly expressed in PBMC of mice with osteoporosis. Among the 13 miRNAs, the expression trends of miR-1271-5p, miR-135a-5p, miR-135b-5p, miR-153-3p, miR-223-3p, miR-27a-3p, miR-370-3p, and miR-9-5p in the current study were in line with their trends in various studies [ 5 , 7 , 41 – 46 ]. Our result revealed that the expression of the 13 miRNAs was positively correlated with the progression of osteoporosis.…”

A Comprehensive Analysis of MicroRNAs in Human Osteoporosis

“…For instance, dickkopf-1 (DKK1), a powerful antagonist of canonical WNT signaling pathway and biomarker for osteoporosis, was predicted as the shared targets of hsa-miR-133b, -20a-5p, -637, -214-3p, -106a-5p, and -135b-5p in our study. Coincidentally, some studies also revealed that DKK1 was targeted by miR-335-5p, miR-433-3p and miR-135b-5p commonly (29)(30)(31). Besides, another crucial osteoblast differentiation biomarker RUNX2 was regulated by a panel of miRNAs, including miR-204, -23a, -30c, -34a, -133a, and so on (32,33).…”

MicroRNAs Regulation in Osteogenic Differentiation of Mesenchymal Stem Cells

“…miR-338 clusters are elevated in postmenopausal women with OP, and in vivo and in vitro studies suggest that RUNX2 and SOX4 may be two key functional targets of miR-338 by mediating their regulation during bone formation (80). Abnormal expression of miR-135b-5p in bone tissue of OP patients suggests that miRNA is involved in the occurrence and development of OP (81). Interestingly, TAmiRNA, a European miRNA diagnostics company, recently commercialized a product called Osteo-miR panel, which uses a set of 19 miRNA to identify the first fracture risk of postmenopausal osteoporosis and type 2 diabetes women (82).…”