[Methylation and expression of RUNX3 gene promoter in papillary thyroid carcinoma].

OBJECTIVE: To study the relationship between status of methylation of human runt-related transcription factor 3 (RUNX3) gene promoter in papillary thyroid carcinoma (PTC). METHODS: Methylation-specific PCR and immunohistochemical SP technique were used to detect the methylation of RUNX3 gene promoter and expression of its protein in 56 cases of PTC and their matched adjacent non-carcinous epithelium (NCE). RESULTS: In NCE, there was no methylation of RUNX3 gene promoter, while in PTC the methylation rate was 35.7%(20/56), which was related to the tumor TNM stage, pathological grade and lymph node metastasis (P < 0.05). The positive rates of RUNX3 protein expression in NCE and PTC were 100.0% and 60.7%, respectively, with a significant difference (χ(2) = 27.378, P < 0.05). In PTC, the positive rates of RUNX3 protein expression in gradeI and grade II were 70.0% and 37.5%, respectively (P < 0.05); the rates were 46.7% and 76.9% in lymph node metastasis group and no metastasis group, respectively (P < 0.05). Moreover, there was a distinct correlation between methylation of RUNX3 gene promoter and expression of its protein (χ(2) = 21.62, P < 0.01). CONCLUSIONS: Methylation of promoter might be one of the important factors of inactivation of RUNX3 gene, and might play an important role in carcinogenesis and progression of PTC.