Abstract

BACKGROUND
The purpose of this study is to assess the roles of p21 protein, p53 protein, and Ki-67 expressions and apoptosis in colorectal tumorigenesis.
METHODS
Fifty-seven colorectal cancers and 15 villotubular adenomas were investigated by immunohistochemical staining for p21 protein, p53 protein, Ki-67, and in situ labeling of apoptotic cells. Clinicopathologic values (tumor size, histologic grade, Dukes stage, and lymph node metastasis) were compared with the incidence of expressions of p21 protein and p53 protein, index of Ki-67 expression, and apoptosis.
RESULTS
The incidence of p21 protein expression was decreased with lymph node metastasis (p<0.005), and that of p53 expression was increased with lymph node metastasis (p<0.005). There were no statistically significant correlations among the p21 protein or p53 protein expressions, tumor size, histologic grade and stage. The correlation between the Ki-67 labeling index and the clinicopathologic values was not statistically significant. The labeling index of apoptosis was increased with the Astler-Coller stage (p<0.05). Statistical analysis revealed a significant inverse correlation between the p21 protein and p53 protein expressions (p<0.05).
CONCLUSIONS
It is suggested that p21 protein, p53 protein and the apoptotic labeling index are useful variables for the prognostic assessment of colorectal adenocarcinoma. Down-regulation of p21 protein expression may be associated with poor prognosis. Also, the expressions of p21 protein and p53 protein may play an important role in the tumorigenesis and progression of the colorectal adenoma-carcinoma sequence.

• Keywords: Colorectal Neoplasms;Immunohistochemistry;Apoptosis;