Akt expression may predict favorable prognosis in cholangiocarcinoma

Abstract

Overexpression of signaling proteins including epidermal growth factor receptor (EGFR), Akt, mitogen activated protein kinase (MAPK) and cyclooxygenase-2 (COX-2) occurs in cholangiocarcinoma cell lines. However, the prognostic value of these markers is unknown. No prior study correlated the expression of these signaling proteins with clinical outcome. Further, co-expression of these proteins has not been reported. Co-expression may reflect cross-talk between signaling pathways. The aim of this clinicopathological study was to investigate the overexpression and co-expression of EGFR and related signaling proteins in cholangiocarcinoma and explore their relationship to clinical outcome. Twenty-four consecutive cases of cholangiocarcinoma treated from 1996 to 2002 at Roswell Park Cancer Institute were included. Immunohistochemical staining of paraffin-embedded tissue sections was performed using antibodies against Akt, p-Akt, MAPK, p-MAPK, COX-2, EGFR and p-EGFR. Two pathologists independently scored the protein expression. Cyclooxygenase-2, Akt, and p-MAPK were commonly expressed in biliary cancers (100%, 96% and 87% of malignant cells, respectively). EGFR (60%) and p-EGFR (22%) overexpression was also detected. There was a significant association between EGFR and p-EGFR (P = 0.027) and between Akt and p-Akt (P = 0.017) expression in tumor tissue. A noteworthy association was shown between MAPK and p-Akt (P = 0.054). Multivariate analysis using the Cox proportional hazard model identified the use of chemotherapy (hazard ratio [HR] = 0.039, P = 0.0002), radiation (HR = 0.176, P = 0.0441) and Akt expression (HR = 0.139, P = 0.006) as the best predictors of overall prognosis. Epidermal growth factor receptor signaling intermediates are commonly expressed in cholangiocarcinoma. Expression of Akt and use of systemic chemotherapy or radiation may correlate with improved survival.