Our preliminary RNA-Seq data revealed altered expression of small nucleolar RNA host gene 9 (SNHG9) in osteoarthritis (OA) and its reverse correlation with miR-34a, which can regulate chondrocyte apoptosis in rat OA model. This study was therefore carried out to investigate the potential interaction between SNHG9 and miR-34a in OA.
A total of 60 healthy volunteers (Control group) as well as 60 OA patients (OA group) were enrolled in this study. Transfections, RT-qPCR, methylation-specific PCR (MSP) and cell apoptosis assay were performed.
We found that SNHG9 was downregulated in OA and its expression was reversely correlated with the expression of miR-34a only across OA samples but not healthy control samples. In chondrocytes from OA patients, overexpression of SNHG9 led to downregulation of miR-34a and increased methylation of miR-34a gene. In contrast, in chondrocytes from healthy controls, overexpression of SNHG9 did not affect the expression of miR-34a and the methylation of miR-34a gene. Cell apoptosis analysis showed that overexpression of SNHG9 led to decreased apoptotic rate of chondrocytes from OA patients but not chondrocytes from the healthy controls through miR-34a.
In conclusion, SNHG9 is downregulated in OA and inhibits chondrocyte apoptosis by downregulating miR-34a through methylation.