Changes in osteogenic gene expression in hypertrophic chondrocytes induced by SIN-1

The molecular mechanisms underlying osteoarthritis (OA) and Kashin-Beck disease (KBD) remain poorly understood. Hypertrophic chondrocytes serve an important role in the development of both OA and KBD, whereas oxidative stress can contribute to the pathological progression of cartilage damage. Therefore, the aim of the present study was to detect altered expression of osteogenesis-related genes in hypertrophic chondrocytes, following treatment with 3-morpholinosydnonimine (SIN-1). ATDC5 cells were induced to develop into hypertrophic chondrocytes via Insulin-Transferrin-Selenium. The appropriate concentration and time of SIN-1 treatment was determined via MTT assay. Following hypertrophic chondrocyte stimulation with SIN-1, a liquid chip was analyzed using a polymerase chain reaction (PCR) array. Reverse transcription-quantitative PCR was conducted on individual genes to validate the array-based data. Analyses of protein-protein interactions, gene ontology functions and Kyoto Encyclopedia of Genes and Genomes pathway enrichment of the differentially expressed genes were also performed. A total of 6 upregulated and 34 downregulated genes were identified, including the mothers against decapentaplegic homolog (Smad) family (Smad1-4), bone morphogenetic proteins and their receptors (Bmp2, Bmp3, Bmpr1α and Bmpr1β), and matrix metalloproteinases (MMP2,-9 and-10). These genes are associated with collagen biology, transcriptional control, skeletal development, bone mineral metabolism, and cell adhesion. SIN-1 induced death of hypertrophic chondrocytes likely through TGF-β/Smad or BMP/Smad pathways. Oxidative-stress-dependent induction of abnormal gene expression may be associated with chondronecrosis in the cartilage of patients with OA or KBD.