Decreased expression of p27 is associated with malignant transformation and extrathyroidal extension in papillary thyroid carcinoma.

Cell cycle regulatory proteins including p16, p27, and p53 are well studied in various cancers. However, their single or concurrent roles related with the clinicopathological parameters are not clearly recognized. We analyzed the expression of p16, p27, and p53 cell cycle regulatory proteins in papillary thyroid carcinoma (PTC). To determine the prognostic significance of cell cycle regulatory proteins, 107 PTCs were examined. We analyzed the individual expression of p16, p27, and p53 and their concurrent expressions, with the relationship to various clinicopathological parameters including differentiation from benign lesions. High expression of p16 and p53 and low expression of p27 were related with the distinguishing of PTC from benign lesions. In addition, normal thyroidal tissue showed higher p27 expression than nodular hyperplasia. In relation to extrathyroidal extension (ETE), the low expression of p27 was related with the presence of ETE. The low expression of p27 and high expression of p16 and p53 may affect the development of PTC. In addition, low p27 expression is related with the existence of ETE.