Conversion enzyme inhibitors against the progression of renal and vascular diseases: yes but again

p21WAF1/CIP1 is a potent, tight-binding inhibitor of Cdks which is induced by the wild-type p53 gene. We examined p21WAF1/CIP1 mRNA expression in 16 surgically excised human colorectal tumor and nontumor tissues using Northern blot analysis with reference to the identification of p53 gene mutation. p53 gene mutation was detected in six tumor tissues but not in the other 10 using the PCR-SSCP method. The p21WAF1/CIP1 mRNA level was lower in tumor tissues than in the corresponding nontumor tissues. The mean expression level of p21WAF1/CIP1 mRNA was lower in tissues in which the p53 gene mutation was detected than in those in which it was not, although the difference was not significant. The relative p21WAF1/CIP1 mRNA expression level was significantly higher in the tumors with liver metastases than in those without. These results suggest that the p21WAF1/CIP1 mRNA expression level, which might be a indicator of colorectal cancer malignancy, is suppressed in human colorectal tumor tissues compared with the corresponding nontumor tissues and that the wild-type p53 gene is one of the factors inducing p21WAF1/CIP1 mRNA expression.