Vitamin D receptor Bsm I polymorphism and osteoporosis risk in postmenopausal women: a meta-analysis from 42 studies.

OBJECTIVE: This study aimed to quantitatively summarize the evidence for VDR BsmI gene polymorphism and osteoporosis risk in postmenopausal women. MATERIALS AND METHODS: The PubMed, EMBASE, Weipu, CNKI, and Wanfang databases were searched for eligible studies. Case-control studies containing available genotype frequencies of B/b were chosen, and odds ratio (OR) with 95% confidence interval (CI) was used to assess the strength of this association. RESULTS: 4485 osteoporosis and 5490 controls were identified in our meta-analysis. In the stratified analysis, a significant association was observed between VDR BsmI gene polymorphism and osteoporosis susceptibility in Caucasians (additive model: OR = 0.809, 95% CI 0.678~0.965, p = 0.019; recessive model: OR = 0.736, 95% CI 0.568~0.955, p = 0.021; and co-dominant model: bb vs. BB OR = 0.701, 95% CI 0.511~0.962 p = 0.028), and we failed to find any significant relationship in Asians. CONCLUSION: The present meta-analysis suggests that VDR BsmI genotype is associated with increased risk of postmenopausal osteoporosis in Caucasians but not in Asians. To draw comprehensive and true conclusions, further prospective studies with larger numbers of participants worldwide are needed to examine associations between VDR BsmI polymorphism and osteoporosis in postmenopausal women.

Decreased microRNA-182-5p helps alendronate promote osteoblast proliferation and differentiation in osteoporosis via the Rap1/MAPK pathway.

Osteoporosis (OP) is a serious health problem that contributes to osteoporotic structural damage and bone fragility. MicroRNAs (miRNAs) can exert important functions over bone endocrinology. Therefore, it is of substantial significance to clarify the expression and function of miRNAs in bone endocrine physiology and pathology to improve the potential therapeutic value for metabolism-related bone diseases. We explored the effect of microRNA-182-5p (miR-182-5p) on osteoblast proliferation and differentiation in OP rats after alendronate (ALN) treatment by targeting adenylyl cyclase isoform 6 (ADCY6) through the Rap1/mitogen-activated protein kinase (MAPK) signaling pathway. Rat models of OP were established to observe the effect of ALN on OP, and the expression of miR-182-5p, ADCY6 and the Rap1/MAPK signaling pathway-related genes was determined. To determine the roles of miR-182-5p and ADCY6 in OP after ALN treatment, the relationship between miR-182 and ADCY6 was initially verified. Osteoblasts were subsequently extracted and transfected with a miR-182-5p inhibitor, miR-182-5p mimic, si-ADCY6 and the MAPK signaling pathway inhibitor U0126. Cell proliferation, apoptosis and differentiation were also determined. ALN treatment was able to ease the symptoms of OP. miR-182-5p negatively targeted ADCY6 to inhibit the Rap1/MAPK signaling pathway. Cells transfected with miR-182 inhibitor decreased the expression of ALP, BGP and COL I, which indicated that the down-regulation of miR-182-5p promoted cell differentiation and cell proliferation and inhibited cell apoptosis. In conclusion, the present study shows that down-regulated miR-182-5p promotes the proliferation and differentiation of osteoblasts in OP rats through Rap1/MAPK signaling pathway activation by up-regulating ADCY6, which may represent a novel target for OP treatment.

Up-regulation of microRNA-340 promotes osteosarcoma cell apoptosis while suppressing proliferation, migration, and invasion by inactivating the CTNNB1-mediated Notch signaling pathway.

Osteosarcoma (OS) is the most common histological form of primary bone cancer. It is most prevalent in teenagers and young adults. The present study aims at exploring the regulatory effect of microRNA-340 (miR-340) on OS cell proliferation, invasion, migration, and apoptosis via regulating the Notch signaling pathway by targeting ß-catenin (cadherin-associated protein) 1 (CTNNB1). OS tissues belonging to 45 patients and normal femoral head tissues of 45 amputees were selected. Cells were allocated to different groups. In situ hybridization was performed to determine the positive rate of miR-340 expression while immunohistochemistry was used to determine that of CTNNB1 and B-cell lymphoma 2 (Bcl-2). We used a series of experiments to measure the expressions of related factors and assess rates of cell proliferation, migration, invasion, cycle, and apoptosis respectively. Our results show that miR-340 was expressed a higher level in normal tissue than OS tissue. Expression of Notch, CTNNB1, hairy and enhancer of split 1 (Hes1), Bcl-2, Runt-related transcription factor 2 (Runx2), and osteocalcin increased and that of miR-340, Bcl-2 interacting mediator of cell death (BIM), and Bcl-2 associated protein X (Bax) decreased in OS tissues. U-2OS cell line had the highest miR-340 expression. We also found that the up-regulation of miR-340 had increased expression of miR-340, BIM, and Bax but decreased expression of Notch, CTNNB1, Hes1, Bcl-2, Runx2, and osteocalcin. Up-regulation of miR-340p lead to increased cell apoptosis, suppressed cell proliferation, migration, and invasion. Our study demonstrates that overexpression of miR-340 could suppress OS cell proliferation, migration, and invasion as well as promoting OS cell apoptosis by inactivating the Notch signaling pathway via down-regulating CTNNB1. Functional miR-340 overexpression might be a future therapeutic strategy for OS.