Decreased expression of focal adhesion kinase is associated with a poor prognosis in extrahepatic bile duct carcinoma

Abstract

Extrahepatic bile duct (EBD) carcinoma is a relatively rare neoplasm worldwide, and its prognostic outcome remains unfavorable. Therefore, it is necessary to investigate molecular biologic features of EBD carcinomas. Focal adhesion kinase (FAK) plays a pivotal role in cell adhesion, survival, migration, and signal transduction, but FAK expression in EBD carcinomas has not been evaluated. We measured FAK expression in 76 EBD carcinomas using immunohistochemistry and evaluated its correlation with tumor progression, clinicopathologic factors, and patient outcome. FAK was expressed specifically in the cytoplasm of all normal biliary epithelia (100%). Most dysplastic epithelia also showed positive FAK expression except for 2 cases (92%), whereas EBD carcinomas showed positive FAK expression in 53 (77%) of 76 cases (P < .001, versus normal epithelia). FAK expression tended to be gradually reduced along as dysplasia progressed to carcinoma. Although FAK expression had no association with clinicopathologic factors, the positive FAK expression group showed significantly better survival than the negative FAK expression group (P < .05). However, FAK expression was not an independent prognostic factor by multivariate analysis. In conclusion, FAK expression was significantly lower in EBD carcinomas than in normal biliary epithelia and decreased expression of FAK seemed to be indicative of a poor prognosis, suggesting that FAK might play an inhibitory role for tumor progression in EBD carcinomas. It is important to notice the role of FAK in tumor progression when treatments targeting FAK are performed.