Norio Sawabu

5 – Altered Expression of p27 Protein in Pancreatic Carcinoma

This chapter demonstrates the procedures of immunohistochemical analysis of the p27 protein and discusses the relationship among p27 expression, pathologic features, and clinical outcome. Although mutations of the p27 gene have not been demonstrated in human carcinomas, unlike those of p16 or p53 gene, the loss of p27 expression or downregulation of p27 proteins induced by enhanced proteasomal degradation have been shown in many human carcinomas. The p27 gene also may have other roles, including the promotion of apoptosis, the regulation of drug resistance in solid tumors, and the mediation of cell differentiation. Low p27 expression may be a poor prognostic factor for various carcinomas, including those of the colon, stomach, gall bladder, esophagus, breast, and prostate, although some subsequent studies have not confirmed its prognostic value.