Methylation of p16 CpG islands correlated with metastasis and aggressiveness in papillary thyroid carcinoma

Background: Inactivation of p16 by methylation of CpG islands is a frequent early event in human cancers, including papillary thyroid carcinoma (PTC). This study was to observe the methylation status of the p16 gene in papillary thyroid carcinoma (PTC) and its correlation with clinical parameters. Methods: Methylation-specific PCR (MSP) was used to analyze the methylation status of the p16 gene in 74 PTCs and 21 adjacent normal thyroid tissues. Results: Hypermethylation of p16 gene was observed in 27.0% (20/74) of PTC. None of the normal thyroid tissues was methylated, when compared to the PTCs (p < 0.05). There was no marked relationship between the methylation of p16 gene and the patients' age, gender, size of cancer, histological subtypes and occurrence of recurrent disease (p > 0.05). The methylation of p16 gene was positively associated with metastasis, a high AMES (age, metastasis to distant sites, extrathyroidal invasion, size) risk group (p < 0.05) and advanced pathological tumor lymph node-metastasis stages. Conclusion: The methylation of the p16 gene, one event of significance in molecular biology, was common and correlated with biological metastasis and histological features in PTC, and may be involved in thyroid tumorigenesis and aggressiveness. Copyright (C) 2012 Elsevier Taiwan LLC and the Chinese Medical Association. All rights reserved.