p63 and p73 expression in extrahepatic bile duct carcinoma and their clinical significance

p53 plays a pivotal role in the prevention of human tumor formation. p73 and p63 are new members of the p53 tumor suppressor family, which are becoming increasingly recognized as important players in human tumorigenesis. However, the roles of these proteins are not well elucidated in extrahepatic bile duct (EBD) carcinoma. We examined expressions of the p63 and p73 genes and proteins in normal biliary epithelia, biliary dysplasias, and EBD carcinomas using immunohistochemistry and RT-PCR analysis. p63 and p73 proteins were overexpressed in 26.3 and 41.0% of EBD carcinomas, respectively. p63 protein expression was more frequent in tumors with vascular invasion (P = 0.002) and distal location (P = 0.04), while p73 expression was more common in cancers with deeper tumor invasion (P = 0.04). Patients with tumors co-expressing both p63 and p73 were found to have a significantly worse overall survival rate compared to those with either p63 or p73 expression (P < 0.05) as determined in univariate and multivariate analyses. Our results strongly imply that the p53 family members have different functions in EBD carcinomas. Our data also indicate that interactions between p63 and p73 play an important role in tumorigenesis of EBD carcinoma.