Expression of insulin-like growth factor binding protein 6 in retinoic acidinduced apoptosis of chondrocytes

Aim:To investigate gene expression of insulin-like growth factor binding protein 6(IGFBP-6) in retinoic acid-induced apoptosis of rabbit chondrocytes.Methods:Chondrocytes from rabbit were cultured with all-trans retinoic acid(ATRA) at 1×10-6 mol/L for 24 hours.The synthesis of type II collagen and the cell apoptosis were measured in ATRA-treated chondrocytes.Furthermore,the expressions of IGFBP-6 mRNA and protein in chondrocytes were detected by real-time quantitative PCR and Western blotting analysis.Results:The synthesis of type II collagen was down-regulated by ATRA of 1×10-6 mol/L.Exposure to ATRA of 1×10-6 mol/L increased the cell apoptosis by 250% in comparison to the control group(P0.05).There were 140% and 195% increases in the expression levels of IGFBP-6 mRNA and protein in ATRA-treated chondrocytes,respectively(P0.05).Conclusion:The retinoic acid could up-regulate the genetic transcription and translation of IGFBP-6,thereby resulting in chondrocytes apoptosis in vitro.