Methylation of p73 Gene is Associated with Increased Risk of Papillary Thyroid Cancer

This study aimed to investigate the association between methylation in the promoter region of the p73 gene and the clinical features papillary thyroid cancer. Forty-two pairs of papillary thyroid cancer and corresponding paracancerous tissues and blood samples from January to June 2015 were enrolled in this study. The methylation level of the p73 gene and p73 mRNA level were detected by methylation-specific PCR and quantitative reverse transcription-PCR. The correlation between the methylation level of p73 gene and p73 mRNA level was analyzed. The methylation status of p73 and p16 in plasma were also detected, and the correlation between them was analyzed. The results showed that p73 methylation was found at CG sites in 28 cancer tissues, which mainly located at positions 21, 22, 23 CG sites, but methylation was not identified at CG sites in paracancerous tissues (P < 0.01). The methylation level of the p73 gene was negatively correlated with p73 mRNA level (P < 0.01). Methylation of p73 gene was correlated with lymph node metastasis, but not age, sex, clinical stage of the patients. Methylation of p73 in plasma was correlated with methylation of tumor suppressor gene p16, which increased the risk of papillary thyroid cancer. In conclusion, we found that hypermethylation of the p73 gene is associated with the development and metastasis of papillary thyroid cancer, which may be suggested as a new candidate tumor suppressor gene in papillary thyroid cancer.