Correlation Between Caspase-8 Gene Promoter Unmethylation And Protein Expression In Joint Cartilage Cells Of Osteoarthritis Patients

ObjectivesTo investigate the role of cysteinylaspartate specific proteinase 8 (caspase-8) gene promoter hypomethylation in the occurrence and development of osteoarthritis (OA).MethodsGeneral DNA were dealed with Sodium Bisulfite method. The unmethylation status of caspase-8 promoter was detected by Methylation-specific PCR (MSP). Caspase-8 protein expression in joint cartilage cells were detected by Immunohistochemical method.35 OA patients and 14 control patients were recruited from the in-patient of the second Xiangya hospital of Central South University.The results were analyzed by X2 or Fisher's test and Spearman correlation analysis of SPSS 17.0 statistic analysis software.Results1. The positive percent of caspase-8 promoter unmethylation in OA patients and healthy persons were 71.4%(25/35) and 35.7%(5/14) respectively, there was significantly different between the two groups(X2 =5.373,P=0.020).2.1 caspase-8 protein was expressed in joint cartilage cells of all 14 healthy persons.However,13 caspase-8 proteins was expressed in joint cartilage cells of 35 OA patients. Using X2 test, the positive percent of caspase-8 protein in OA patients was significantly higher than that in healthy persons(X2=4.410,P=0.036).3. Promoter unmethylation and protein expression level of caspase-8 gene showed significantly positive correlation.Conclusionscaspase-8 promoter is demethylated in joint cartilage cells of OA patients and healthy persons. The status of unmethylated was higher in joint cartilage cells of OA patients than that in healthy persons.The hypomethylation accelerate the protein expression of caspase-8, which might take a role in the occurrence and development of OA.