Infrequent expression of p21 is related to altered p53 protein in pancreatic carcinoma

This study is designed to investigate the expression of p21 and its relation to altered p53 protein in pancreatic carcinoma (PC). Immunohistochemical staining of formalin-fixed, paraffin-embedded tissue sections of PC was performed using a monoclonal antibody against p21 (187), with a parallel examination of altered p53 protein. The expression of p21 was only found in 12 of 58 (20.7%) PCs and, moreover, was mainly restricted to the well-differentiated ductal epithelium. Sixty-four % (37 of 58) of PCs showed positive p53 staining, and this change was significantly related to the absence of p21 expression (P < 0.01). In a subgroup, the proportion of the undetectable p21 expression and the expression of p53 were increased with increasing tumor grade but decreased with advancing clinical stage. The results of the present study suggest that the absence of p21 expression is very common in PCs and appears to relate to altered p53 protein. Moreover, the abnormalities involving the expression of p21 and p53 may play a more important role in the development than in the progression of this malignancy.