Abstract
Osteoarthritis is the most frequent chronic bone-joint disease in middle-aged and older people worldwide. This study investigated the effects of long noncoding RNA metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) on lipopolysaccharide (LPS)-induced murine chondrogenic ATDC5 cell inflammatory injury. Cell viability and apoptosis were assessed using cell counting kit-8 assay and annexin V-phycoerythrin (PE) staining, respectively. The expression levels of interleukin-1β (IL)-1β, IL-6, IL-8, tumor necrosis factor α (TNF-α), MALAT1, and microRNA-19b (miR)-19b were measured using quantitative reverse-transcription polymerase chain reaction. Enzyme-linked immunosorbent assay was conducted to detect the concentrations of IL-1β, IL-6, IL-8, and TNF-α in culture supernatant of ATDC5 cells. Expressions of key factors involved in cell apoptosis, proinflammatory response, Wnt/β-catenin, and nuclear factor κB (NF-κB) pathways were analyzed using Western blot analysis. We found that LPS treatment remarkably induced ATDC5 cell apoptosis and inflammatory injury. MALAT1 was upregulated in LPS-stimulated ATDC5 cells. Overexpression of MALAT1 significantly reversed the LPS-induced ATDC5 cell inflammatory injury, while suppression of MALAT1 had opposite effects. Further results showed that MALAT1 positively regulated the expression of miR-19b in ATDC5 cells. Knockdown of miR-19b reversed the protective effect of MALAT1 on LPS-induced ATDC5 cells. In addition, MALAT1 reduced LPS-induced Wnt/β-catenin and NF-κB pathways activation in ATDC5 cells by upregulating miR-19. To conclude, our research verified that MALAT1 alleviated LPS-induced ATDC5 cell inflammatory injury by upregulating miR-19b and inactivating Wnt/β-catenin and NF-κB pathways. This finding will be helpful for further understanding the critical roles of MALAT1 and miR-19b in osteoarthritis and may provide possible targets for osteoarthritis diagnosis and treatment.