Abstract
Osteoarthritis is the most frequent chronic bone and joint diseases in older populations all over the world. Lipopolysaccharide (LPS)-induced murine chondrogenic ATDC5 cell model has been widely used for testing new osteoarthritis therapeutic targets. This study aimed to explore the effects of microRNA-136 (miR-136) on LPS-induced ATDC5 cell injury and inflammatory cytokine expression, as well as underlying potential mechanism. We found that LPS remarkably inhibited ATDC5 cell viability, induced ATDC5 cell apoptosis, and upregulated the expression of inflammatory cytokines, including interleukin 1β (IL-1β), IL-6, IL-8, and tumor necrosis factor α (TNF-α; P < .01 or < .001). Moreover, LPS obviously upregulated the expression of miR-136 in ATDC5 cells (P < .05). Overexpression of miR-136 markedly exacerbated the LPS-induced ATDC5 cell viability inhibition, cell apoptosis enhancement, and inflammatory cytokine expression (P < .05), and suppression of miR-136 had opposite effects (P < .05). Myeloid cell leukemia 1 (Mcl-1) was a direct target gene of miR-136, which participated in the effect of miR-136 on LPS-induced ATDC5 cell inflammatory injury. Overexpression of Mcl-1 alleviated the LPS-induced inactivation of Wnt/β-catenin and Janus kinase/signal transducer and activator of transcription (JAK/STAT) signaling pathways, while suppression of Mcl-1 had opposite effects. To conclude, this study verified that miR-136 promoted LPS-induced ATDC5 cell injury and inflammatory cytokine expression by targeting Mcl-1, and Mcl-1 was involved in the regulatory effects of LPS on Wnt/β-catenin and JAK/STAT signaling pathways in ATDC5 cells.