Expression of Cell Cycle-related Proteins p16, p27 and Ki-67 Proliferating Marker in Laryngeal Squamous Cell Carcinomas and in Laryngeal Papillomas

Abstract

Background: The deregulation of the cell cycle is crucial for the processes of carcinogenesis and tumor progression. The cell cycle is under the control of cyclin-dependent kinases (CDKs) and their inhibitors (CDKIs). Proteins p16 and p27 are CDKIs, and their altered expression has been noticed in many types of cancers. The aim of this study has been to compare the expression levels of these proteins in laryngeal papillomas and carcinomas in order to confirm their predictive value in cancer development.

Materials and methods: Eighty-three cases of laryngeal lesions were analyzed: cancers (51) and papillomas (32). Immunohistochemical (IHC) reactions were performed in order to detect the expression levels of p16, p27 and Ki-67. Immunofluorescence (IF) and western blot were performed on HEp-2 cell line.

Results: The expression of p16 and p27 was decreased in cancer cells in comparison to papillomas. Additionally, we observed cytoplasmic expression of p16 in cancers and lack of such expression in papillomas. The same pattern of expression of p16 was also detected by IF and western blot analysis in HEp-2 cell line. The expression of Ki-67 protein revealed no significant differences in the case of papilloma compared with cancer, however a significant correlation between tumor grade and the nuclear expression of Ki-67 was observed.

Conclusion: There is a necessity in finding biomarkers, which would predict the risk level of malignant transformation. Our study has confirmed that altered expressions of the p16 and p27 proteins might be useful biomarkers in the progression of laryngeal squamous cell carcinomas (LSCC).

Keywords: Laryngeal Squamous Cell Carcinoma; Papilloma; p16; p27.