MiR-375 Mediates Chondrocyte Metabolism and Oxidative Stress in Osteoarthritis Mouse Models through the JAK2/STAT3 Signaling Pathway.

OBJECTIVE: The aim of this work was to determine the effect of miR-375 on chondrocyte metabolism and oxidative stress in osteoarthritis (OA) mouse models through the JAK2/STAT3 signaling pathway. METHODS: Chondrocytes were divided into control, IL-1ß, IL-1ß + miR-375 mimic, IL-1ß + miR-375 inhibitor, IL-1ß + miR-NC (negative control), and IL-1ß + miR-375 inhibitor + siJAK2 groups. The chondrocyte proliferation was determined by MTT assay, the superoxide dismutase (SOD) and malondialdehyde (MDA) levels by corresponding kits, and the chondrocyte apoptosis by TUNEL staining. Furthermore, OA mouse models were divided into Sham, OA + miR-NC, and OA + miRNA-375 antagomir groups. The pathological changes were observed, and the expressions of miR-375 and the JAK2/STAT3 pathway were determined by qRT-PCR and Western blotting, respectively. RESULTS: IL-1ß-induced chondrocytes had significant increases in miR-375 and MDA, with decreased proliferation and SOD levels, as compared to the control group. Meanwhile, they also exhibited elevated apoptosis, with upregulations of ADAMTS-5 and MMP-13 and downregulations of COL2A1 and ACAN, as well as decreased p-JAK2/JAK2, p-STAT3/STAT3, and Bcl-2/Bax. However, these changes were significantly improved after transfection with miR-375 inhibitor, but transfection with miR-375 mimic resulted in severer exacerbation. Notably, the improvement of miR-375 inhibitor could be abolished by transfection with siJAK2. Furthermore, miR-375 antagomir significantly alleviated OA progression in OA mice in vivo. CONCLUSION: MiR-375 suppression enhanced the ability of chondrocyte to antagonize the oxidative stress and maintained the homeostasis of extracellular matrix metabolism to protect chondrocytes from OA via activation of the JAK2/STAT3 pathway, indicating that miR-375 is a potential molecular target for OA treatment.

TET1 partially mediates HDAC inhibitor-induced suppression of breast cancer invasion.

Histone deacetylases (HDACs) are important in chromatin remodeling and epigenetic regulation of gene expression. Histone deacetylase inhibitors (HDACi) have highly effective anti-metastatic and anti-angiogenic activity in various types of cancer, while the molecular mechanisms involved in this process are not fully understood. In the present study, trichostatin A (TSA), a HDACi, was found to suppress MCF-7 breast carcinoma cell invasion and upregulate TET1 expression in a dose-dependent manner. TET1, a dioxygenase involved in cytosine demethylation, is downregulated during breast cancer progression. TET1 knockdown in MCF-7 cells facilitates cell invasion, inhibits the expression of tissue inhibitors of metalloproteinase 2/3 (TIMP2/3) and promotes matrix metalloproteinases (MMP) 2/9 transcriptional activity. Importantly, TET1 depletion impaired the inhibitory effect of TSA on breast cancer cell invasion. Together, these results illustrated a mechanism by which TET1 partially mediates HDACi elicited suppression of breast cancer invasion.