Effects of C-myc gene silencing on interleukin-1β-induced rat chondrocyte cell proliferation, apoptosis and cytokine expression

This study explores the effects of C-myc gene silencing on cell proliferation, apoptosis and cytokine expression in interleukin (IL)-1 beta-induced rat chondrocytes. Primary chondrocytes were obtained from 40 Sprague-Dawley rats. For in vitro C-myc3-shRNA transfection, chondrocytes were assigned to a blank 1, model 1, IL-1 beta + C-myc3-shRNA, C-myc3-shRNA, (IL-1 beta + C-myc3-shRNA) + C-myc overexpression, C-myc3-shRNA + C-myc overexpression or IL-1 beta + C-myc-Con group. Western blotting and quantitative real-time polymerase chain reaction (qRT-PCR) were performed to detect C-myc, PCNA and cyclin D1 mRNA and protein expression. Cell proliferation was analyzed via CCK-8 assay and cell cycle while apoptosis was measured through flow cytometry. ELISA was utilized to assess the levels of metallopeptidase 13 (MMP-13), IL-6 and tumor necrosis factor-alpha (TNF-alpha). Both the qRT-PCR and Western blotting results demonstrated that C-myc3-shRNA transfection inhibits C-myc expression and promotes PCNA and cyclin D1 expression. In comparison to the model 1 group, all groups except the (IL-1 beta + C-myc3-shRNA) + C-myc overexpression and IL-1 beta + C-myc-Con groups showed increases in cell proliferation and S phase cell count and decreases in G(0)/G(1) phase cell count, cell apoptosis and MMP-13, IL-6 and TNF-alpha levels. The model 1, C-myc3-shRNA and C-myc3-shRNA + C-myc overexpression groups displayed higher cell proliferation and S phase cell count and reduced G(0)/G(1) phase cell count, cell apoptosis and MMP-13, IL-6 and TNF-alpha levels than the IL-1 beta + C-myc3-shRNA group. In comparison to the model 1 and C-myc3-shRNA + C-myc overexpression groups, the C-myc3-shRNA group promoted cell proliferation and S phase cell counts but suppressed G(0)/G(1) phase cell count, cell apoptosis and MMP-13, IL-6 and TNF-alpha levels. In conclusion, the study demonstrates that C-myc gene silencing can promote cell proliferation and inhibit cell apoptosis and cytokine expression in IL-1 beta-induced rat chondrocytes.