Immunoexpression of p53 and p21 [WAF1/CIP1] proteins in colorectal cancer: correlation with clinicopathological parameters

ABSTRACT

Both p53 and p21 [WAF1/CIP1] proteins belong to the cell cycle-regulating family of proteins, and the loss of their activity seems to be one of the most important regulatory mechanisms of carcinogenesis in colorectal cancer. The aim of this study was to evaluate the tumor suppressor genes p53 and p21 [WAF1/CIP1] expressions in colorectal cancer and assessment the relationship between p2 [WAF1/CIP1] and p53 immunoreactivity with special emphasis on the prognostic significance of their expression with variable clinicopathologic parameters. Tissue sections from 50 formalin-fixed and paraffin-embedded tumor specimens were examined. The standard streptavidin-biotin immunoperoxidase method was used for immunostaining of p53 protein and p2[WAF1/CIP1] protein.The extent of positive p53 and p21 [WAF1/CIP1] staining was graded semiquantitatively. The clinicopathologic and prognostic features were statistically analyzed. Over-expression of p53 and p2l [WAF1/CIP1] were found in 27 cases [54%] and 22 cases [44%] respectively. Statistical analyses revealed a highly significant correlation between p21 [WAF1/CIP1] and p53 immunopositivity [p=0.003]; but no significant correlation could be calculated between p53 or p21 [WAF1/CIP1] proteins expression with the Clinicopathological parameters such as [age, sex, tumor size, gender, TNM staging, and vascular invasion] except there was significant statistical correlation of p53 expression with tumor type [p<0.05]. Our investigation results suggest that p53 and p2l [WAF1/CIP1] immunoexpression are common findings in colorectal cancer and the induction of p21 [WAF1/CIP1] occur in a p53-dependent or independent pathways