MicroRNA-4287 alleviates inflammatory response via targeting RIPK1 in osteoarthritis.

Studies have confirmed the regulatory effects of microRNAs (miRNAs) in osteoarthritis (OA) progression. MiR-4287 has been identified by a previous study as a downregulated miRNA in chondrocytes treated with IL-1ß and TNF-α. However, the function of the underlying mechanism of miR-4287 in OA is elusive. IL-1ß-treated chondrocytes were used as OA cell models. RNA expression was accessed using RT-qPCR. Cell Counting Kit-8 (CCK-8) assay was used to determine the chondrocytes' viability and proliferation. The protein levels of inflammation factors (IL-8, IL-6, and TNF-α), matrix metalloproteinases (MMP 1, MMP3, MMP13), and chondrogenic genes (COL2A1, SOX9, and Aggrecan) were detected using western blot analysis. Luciferase reporter assays were performed for interaction exploration. HE staining and Safranin O/Fast Green staining was used to access the pathological changes in OA mouse tissues and cartilage degeneration in OA mouse. MiR-4287 was downregulated in chondrocytes treated with IL-1ß and OA mouse models. MiR-4287 overexpression promoted the viability, and proliferation and attenuated the inflammation response and destruction of cartilage in IL-1ß-stimulated chondrocytes. Receptor-interacting protein kinase 1 (RIPK1) was a target gene of miR-4287 in chondrocytes. MiR-4287 negatively regulated RIPK1 expression. RIPK1 overexpression was revealed to reverse the miR-4287-mediated effects on proliferation and inflammatory response in IL-1ß-stimulated chondrocytes. Moreover, miR-4287 was demonstrated to inhibit the pathological changes, cartilage degeneration and inflammation response in OA mice models. In conclusion, miR-4287 is a critical molecule in OA development, which attenuates inflammatory response in vivo and in vitro by targeting RIPK1.

MicroRNA-4287 is a novel tumor suppressor microRNA controlling epithelial-to mesenchymal transition in prostate cancer.

Prostate cancer (PCa) is a significant cause of male morbidity in the United States. Despite recent advances in diagnosis and therapeutic interventions, significant fraction of cases still progress to an advanced stage. Various genetic/epigenetic elements that facilitate this progression are not yet completely known and the mechanism that favors advanced disease is an area of investigation. A characteristic feature associated with progressive disease is deletion of chromosome 8p (chr8p) region, that harbors tumor-suppressor NKX3.1. Previous studies from our group has shown that there are cluster of microRNAs (miRNAs) located within this region whose loss favors advanced, metastatic disease. miR-4287 is a novel miRNA located within this region that has not been studied before. In the present study, we analyzed the role of miR-4287 in PCa using clinical tissues and cell lines. We observed that miR-4287 is significantly downregulated in patient-derived tumor tissues. Receiver operating curve (ROC) analysis showed that miR-4287 distinguishes prostate cancer from normal with a specificity of 88.24% and with an Area under the curve (AUC) of 0.66. Further, we found that miR-4287 levels correlate inversely with patients' serum prostate-specific antigen levels. Ectopic over-expression of miR-4287 in PCa cell lines showed that miR-4287 plays a tumor suppressor role. miR-4287 led to an increase in G2/M phase of cell cycle in PCa cell lines. Further, ectopic miR-4287 inhibited PCa epithelial-to-mesenchymal transition (EMT) by directly repressing SLUG and stem cell marker CD44. Since miR-4287 specifically targets metastasis pathway mediators, miR-4287 has potential diagnostic and therapeutic significance in preventing advanced, metastatic disease.

[Effect of chondrogenesis related miR-4287 on expression of aggrecanase-1 in human chondrocytes].

Objective: To investigate the effect and mechanism of miR-4287, a chondrogenesis associated microRNA, regulated the expression of aggrecanase-1 (a disintegrin and metalloproteinase with thrombospondin motif 4, ADAMTS4) in human chondrocytes. Methods: First, the voluntarily donated normal and osteoarthritic knee articular cartilages were used to detect the expressions of miR-4287 and ADAMTS4 mRNA by real-time fluorescence quantitative PCR. Then, chondrocytes were isolated from knee articular cartilages. The effect of IL-1ß on the expression of miR-4287 and ADAMTS4 mRNA was validated by the first generation of osteoarthritic chondrocytes. To confirm the influence of IL-1ß signal pathways on the expression of miR-4287 and ADAMTS4 mRNA, osteoarthritic chondrocytes were pretreated with MAPK signal pathway inhibitor SP600125, NF-κB pathway inhibitor SN50, and finally stimulated with IL-1ß. Chondro cytes were transfected with miR-4287 mimics and mimics negative control, inhibitors and inhibitors negative control respectively to value the effect of miR-4287 on ADAMTS4 expression. Luciferase reporter assay was used to verify the direct interaction between miR-4287 and putative site in the 3-untranslated region (3'UTR) of ADAMTS4 mRNA. Results: Compared with normal knee articular cartilages, the miR-4287 expression was markedly diminished and conversely ADAMTS4 mRNA expression was raised in osteoarthritis cartilages ( P<0.05). Stimulation with IL-1ß led to a reduction in miR-4287 expression and upregulation in ADAMTS4 mRNA expression, showing significant difference when compared with the untreated groups ( P<0.05). Pretreatment with IL-1ß signal pathway inhibitors induced miR-4287 expression and attenuated ADAMTS4 mRNA expression in human chondrocytes, which were significantly different from that of unstimulated cells ( P<0.05). ADAMTS4 mRNA and protein were suppressed by transfection with miR-4287 mimics ( P<0.05) and elevated by transfection with miR-4287 inhibitors ( P<0.05). As luciferase reporter assay showed, overexpression miR-4287 failed to alter the luciferase activity of a reporter construct containing either wild or mutant 3'UTR of ADAMTS4 mRNA ( P>0.05). Conclusion: miR-4287, a chondrogenesis associated microRNA, may play an important role in cartilage degeneration. miRNA-4287 is able to regulate ADAMTS4 expression in human chondrocytes, but not by means of directly targeted the ADAMTS4 mRNA 3'UTR. The exact mechanisms need to be further addressed.