Roles of Cell Cyle Regulators Cyclin D1, CDK4, and p53 in Knee Osteoarthritis.

Objective: The aim of this study was to investigate the roles of cyclin D1, CDK4, and p53 in knee osteoarthritis (KOA).

Methods: A total of 76 healthy controls and 154 KOA cases (grades ranging from II to IV) were recruited. Protein expression of cyclin D1, CDK4, and p53 were detected by immunohistochemistry, and mRNA expression levels of the cyclin D1, the CDK4, and the p53 genes were measured by reverse transcription-polymerase chain reaction.

Results: Both protein and mRNA expression levels of cyclin D1 and CDK4 were significantly lower in KOA cases than those in healthy controls, while protein and mRNA expression of p53 was significantly higher in KOA cases than that in healthy controls (all p < 0.05). As the grades of KOA increased, Cyclin D1 and CDK4 mRNA expressions decreased, whereas p53 mRNA expression increased (all p < 0.05). In KOA cases, mRNA expression of Cyclin D1 was positively correlated to CDK4 mRNA levels (r = 0.386, p < 0.001), while negatively correlated with p53 mRNA levels (r = -0.227, p = 0.005).

Conclusions: Expression of the Cyclin D1, CDK4, and p53 genes are correlated with the disease grades of KOA.