Methylation of promoter and expression of FHIT gene in differentiated thyroid carcinoma tissue

Aim: To study the relationship between status of methylation of fragile histidine triad(FHIT) gene promoter and expression of its protein in differentiated thyroid carcinoma(DTC).Methods:PCR-based restriction enzyme assay and immunohistochemical SP technique were used to detect the status of methylation of FHIT gene promoter and expression of its protein in 65 cases of DTC and their matched adjacent non-carcerous epithelium(NCE).Results:In NCE,there was no promoter methylation of FHIT gene,while in DTC the rate was 24.6%(16/65),and it was related to the tumor TNM stage,pathological grade and lymph node metastasis(P0.05).The positive rate of FHIT expression in NCE and DTC was 100.0%(65/65) and 41.5%(27/65),respectively,and there was significant difference(P0.05).In DTC,the positive rates of FHIT expression in gradeⅠand grade Ⅱ were 53.5% and 18.2%,respectively;in lymph node metastasis group and no metastasis group,it was 15.4% and 59.0% respectively,and there was significant difference between the two groups(P0.05).There was distinct correlation between methylation of FHIT gene promoter and expression of its protein(P0.05).Conclusion: Methylation of promoter might be one of the important factors of inactivation of FHIT gene,and might play an important role in carcinogenesis and progression of DTC.