microRNA-186 inhibition of PI3K-AKT pathway via SPP1 inhibits chondrocyte apoptosis in mice with osteoarthritis.

Chondrocyte apoptosis has been implicated as a major pathological osteoarthritis (OA) change in humans and experimental animals. We evaluate the ability of miR-186 on chondrocyte apoptosis and proliferation in OA and elucidate the underlying mechanism concerning the regulation of miR-186 in OA. Gene expression microarray analysis was performed to screen differentially expressed messenger RNAs (mRNAs) in OA. To validate the effect of miR-186 on chondrocyte apoptosis, we upregulated or downregulated endogenous miR-186 using mimics or inhibitors. Next, to better understand the regulatory mechanism for miR-186 governing SPP1, we suppressed the endogenous expression of SPP1 by small interfering RNA (siRNA) against SPP1 in chondrocytes. We identified SPP1 is highly expressed in OA according to an mRNA microarray data set GSE82107. After intra-articular injection of papain into mice, the miR-186 is downregulated while the SPP1 is reciprocal, with dysregulated PI3K-AKT pathway in OA cartilages. Intriguingly, miR-186 was shown to increase chondrocyte survival, facilitate cell cycle entry in OA chondrocytes, and inhibit chondrocyte apoptosis in vitro by modulation of pro- and antiapoptotic factors. The determination of luciferase activity suggested that miR-186 negatively targets SPP1. Furthermore, we found that the effect of miR-186 suppression on OA chondrocytes was lost when SPP1 was suppressed by siRNA, suggesting that miR-186 affected chondrocytes by targeting and depleting SPP1, a regulator of PI3K-AKT pathway. Our findings reveal a novel mechanism by which miR-186 inhibits chondrocyte apoptosis in OA by interacting with SPP1 and regulating PI3K-AKT pathway. Restoring miR-186 might be a future therapeutic strategy for OA.

Lin Z ，Tian XY ，Huang XX ，He LL ，Xu F ... -  《-》

MiR-34a Enhances Chondrocyte Apoptosis, Senescence and Facilitates Development of Osteoarthritis by Targeting DLL1 and Regulating PI3K/AKT Pathway.

Osteoarthritis (OA) is the prevalent degenerative disease caused by various factors. MicroRNAs are important regulators in the inflammation and immune response. The aim of this study was to investigate the effect of microRNA-34a (MiR-34a) on the death of chondrocytes, senescence, as well as its role in OA progression. A series of experiments involving CCK-8, flow cytometry, β-galactosidase staining and wound healing assays were conducted to determine the cellular capabilities of proliferation, cell apoptosis, senescence and the ability of cells to recover from injury, respectively. Binding sites between miR-34a and delta-like protein 1 (DLL1) were identified using a luciferase reporter system, whereas mRNA and protein expression of target genes was determined by RT-PCR and immunoblot, respectively. OA model was generated via surgery. We found that miR-34a expression was increased in the cartilage of OA patients. In rat chondrocytes and chondrosarcoma cells, miR-34a transfections noticeably inhibited the expression of DLL1, triggered cell death and senescence, suppressed proliferation, and prevented scratch assay wound closure. However, transfection of a miR-34a inhibitor displayed adverse effects. Additionally, secretion and expression of factors associated with cartilage degeneration were altered via miR-34a. Moreover, miR-34a directly inhibits DLL1 mRNA. Furthermore, concentrations of DLL1, total PI3K, and p-AKT declined in chondrocytes that overexpress miR-34a. DLL1 overexpression elevated PI3K and p-AKT levels, and eliminated cell death triggered by a miR-34a mimic. In vivo, miR-34a remarkably inhibited miR-34a up-regulation, while enhanced the level of DLL1 expression. In the knee joints of surgery-induced OA rats, articular chondrocyte death and loss of cartilage were attenuated via miR-34a antagomir injection. These findings indicate that miR-34a contributes to chondrocyte death, causing OA progression through DLL1 and modulation of the PI3K/AKT pathway.

Zhang W ，Hsu P ，Zhong B ，Guo S ，Zhang C ，Wang Y ，Luo C ，Zhan Y ，Zhang C ... -  《-》

microRNA-206 is required for osteoarthritis development through its effect on apoptosis and autophagy of articular chondrocytes via modulating the phosphoinositide 3-kinase/protein kinase B-mTOR pathway by targeting insulin-like growth factor-1.

microRNA (miR) has been shown to be involved in the treatment of diseases such as osteoarthritis (OA). This study aims to investigate the role of miR-206 in regulating insulin-like growth factor-1 (IGF-1) in chondrocyte autophagy and apoptosis in an OA rat model via the phosphoinositide 3-kinase (P13K)/protein kinase B (AKT)-mechanistic target of rapamycin (mTOR) signaling pathway. Wistar rats were used to establish the OA rat model, followed by the observation of histopathological changes, Mankin score, and the detection of IGF-1-positive expression and tissue apoptosis. The underlying regulatory mechanisms of miR-206 were analyzed in concert with treatment by an miR-206 mimic, an miR-206 inhibitor, or small interfering RNA against IGF-1 in chondrocytes isolated from OA rats. Then, the expression of miR-206, IGF-1, and related factors in the signaling pathway, cell cycle, and apoptosis, as well as inflammatory factors, were determined. Subsequently, chondrocyte proliferation, cell cycle distribution, apoptosis, autophagy, and autolysosome were measured. OA articular cartilage tissue exhibited a higher Mankin score, promoted cell apoptotic rate, increased expression of IGF-1, Beclin1, light chain 3 (LC3), Unc-51-like autophagy activating kinase 1 (ULK1), autophagy-related 5 (Atg5), caspase-3, and Bax, yet exhibited decreased expression of miR-206, P13K, AKT, mTOR, and Bcl-2. Besides, miR-206 downregulated the expression of IGF-1 and activated the P13K/AKT signaling pathway. Moreover, miR-206 overexpression and IGF-1 silencing inhibited the interleukins levels (IL-6, IL-17, and IL-18), cell apoptotic rate, the formation of autolysosome, and cell autophagy while promoting the expression of IL-1β and cell proliferation. The findings from our study provide a basis for the efficient treatment of OA by investigating the inhibitory effects of miR-206 on autophagy and apoptosis of articular cartilage in OA via activating the IGF-1-mediated PI3K/AKT-mTOR signaling pathway.

Yu Q ，Zhao B ，He Q ，Zhang Y ，Peng XB ... -  《-》

MiR-128-3p Post-Transcriptionally Inhibits WISP1 to Suppress Apoptosis and Inflammation in Human Articular Chondrocytes via the PI3K/AKT/NF-κB Signaling Pathway.

Chen S ，Li B 《-》

Targeting of SPP1 by microRNA-340 inhibits gastric cancer cell epithelial-mesenchymal transition through inhibition of the PI3K/AKT signaling pathway.

Gastric cancer (GC) is a common heterogeneous disease. The critical roles of microRNA-340 (miR-340) in the development and progression of GC were emphasized in accumulating studies. This study aims to examine the regulatory mechanism of miR-340 in GC cellular processes. Initially, microarray technology was used to identify differentially expressed genes and regulatory miRs in GC. After that, the potential role of miR-340 in GC was determined via ectopic expression, depletion, and reporter assay experiments. Expression of secreted phosphoprotein 1 (SPP1), miR-340, phosphatidylinositol 3-kinase/protein kinase B (PI3K/AKT) pathway, and epithelial-mesenchymal transition (EMT)-related genes was measured. Moreover, to further explore the function of miR-340 in vivo and in vitro, proliferation, apoptosis, migration, invasion, and tumorigenic capacity were evaluated. SPP1 was a target gene of miR-340 which could then mediate the PI3K/AKT signaling pathway by targeting SPP1 in GC. Furthermore, miR-340 levels were reduced and SPP1 was enriched in GC tissues and cells, with the PI3K/AKT signaling pathway being activated. Inhibitory effects of upregulated miR-340 on SPP1 and the PI3K/AKT signaling pathway were confirmed in vivo and in vitro. Overexpression of miR-340 or the silencing of SPP1 inhibited GC cell proliferation, invasion, migration, and EMT process, but promoted apoptosis of GC cells. Typically, targeting of SPP1 by miR-340 may contribute to the inhibition of proliferation, migration, invasion, and EMT of GC cells via suppression of PI3K/AKT signaling pathway.

Song SZ ，Lin S ，Liu JN ，Zhang MB ，Du YT ，Zhang DD ，Xu WH ，Wang HB ... -  《-》