Expression of p16(INK4A), Rb and E2F-1 Proteins in Colorectal Carcinoma

ABSTRACT

PURPOSE: An altered cell cycle regulation may underline the development and progression of human malignancies. The purpose of this study was to determine whether the degree of p16(INK4A), Rb and E2F-1 expressions are related to certain parameters such as histologic differentiation, T-stage, lymph node metastasis and TNM stage in colorectal carcinoma. The correlation between the above proteins were compared. METHODS: Immunohistochemical stain was perfomed, for p16(INK4A), Rb and E2F-1 on 84 formalin-fixed paraffin-embedded tissue sections of colorectal adenocarcinomas. RESULTS: The overall expression frequencies of the p16(INK4A), Rb and E2F-1 were 54.8 (46/84), 76.2 (64/84) and 48.8% (41/84), respectively. Loss of the p16(INK4A) expression frequency was higher with a poorly differentiated histologic grade, the presence of nodal metastasis and higher TMN stage. The expression of Rb was not correlated with any of the parameters studied. The frequency of the E2F-1 expression was higher with a poorly differentiated histologic grade, the presence of nodal metastasis and higher TNM stage. A highly significant inverse correlation between the expressions of p16(INK4A) and E2F-1 was observed. CONCLUSION: These data suggest that the loss of p16(INK4A) expression and the expression E2F-1 may play roles in the progression of colorectal adenocarcinomas and could possibly be used as prognostic factors. Further studies to determine the relationships in the expressions of p16(INK4A), Rb and E2F-1 will be required.