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.

Effects of MicroRNA-206 on Osteosarcoma Cell Proliferation, Apoptosis, Migration and Invasion by Targeting ANXA2 Through the AKT Signaling Pathway.

BACKGROUND/AIMS: This study aimed to investigate the mechanism by which microRNA-206 (miR-206) affects the proliferation, apoptosis, migration and invasion of osteosarcoma (OS) cells by targeting ANXA2 via the AKT signaling pathway. METHODS: A total of 132 OS tissues and 120 osteochondroma tissues were examined in this study. The targeting relationship between miR-206 and ANXA2 was verified with a dual-luciferase reporter assay. The miR-206 expression and ANXA2, AKT, PARP, FASN, Survivin, Bax, Mcl-1 and Bcl-1 mRNA and protein expression in the above two groups were examined by qRT-PCR and western blotting. The cultured OS cells were divided into 6 groups: a blank group, negative control (NC) group, miR-206 mimic group, miR-206 inhibitor group, si-ANXA2 group and miR-206 inhibitor + si-ANXA2 group. Cell cycle and apoptosis were assessed by flow cytometry, cell migration was examined with a wound-healing assay, and cell invasion was assessed with a Transwell assay. Pearson correlation analysis was used to determine the correlation between ANXA2 mRNA expression and miR-206 expression in OS. RESULTS: OS tissues exhibited increased mRNA and protein expression of ANXA2, AKT, PARP, FASN, Survivin, Mcl-1 and Bcl-2; decreased miR-206 expression; and decreased Bax mRNA and protein expression. ANXA2 mRNA expression was strongly negatively correlated with miR-206 expression in OS. ANXA2 was found to be a miR-206 target gene. In the miR-206 mimic group and the si-ANXA2 group, the mRNA and protein expression of ANXA2, AKT, PARP, FASN, Survivin, Mcl-1 and Bcl-1 decreased markedly, cell proliferation was inhibited, apoptosis was promoted, higher cell growth in G1 phase and decreased growth in S phase was detected, and decreased cell migration and invasion were observed compared with those in the blank group. CONCLUSION: The current results demonstrate that miR-206 overexpression inhibits OS cell proliferation, migration and invasion and promotes apoptosis through targeting ANXA2 by blocking the AKT signaling pathway.