High expression of ABCC1 indicates poor prognosis in intrahepatic cholangiocarcinoma

Intrahepatic cholangiocarcinoma (ICC) is a serious health problem in Thailand. To reach a cure, radical resection is the gold standard but most patients are not candidates because of delayed first presentation. Palliative surgery and/or combined chemotherapy are alternatives; however, outcomes are still unsatisfactory. A low response to multiple anticancer drugs might be due to a multidrug resistance (MDR) phenotype of ICC. In this study, we investigated the expression profile of selected adenosine triphosphate binding cassette (ABC) transporter superfamily members, the major contributors to cancer MDR, and determined the clinical significance of certain examples in ICC. Expression of 9 ABC transporters; ABCB1, ABCB11, ABCC1, ABCC2, ABCC3, ABCC4, ABCC6, ABCC11 and ABCG2, was determined in 55 ICC tissues using real-time RT-PCR. The results showed that ABCC1, ABCC2, ABCC3 and ABCC4 were differentially expressed in ICC tissues. Only ABCC1 expression was significantly higher in ICC tissues than those of the corresponding non-tumor tissues (P<0.001), significantly correlating with shortened overall survival time (P<0.05). Multivariate analysis indicated that expression is an independent clinicopathological factor (adjusted HR=5.689; 95%CI=1.042-31.076; P<0.05). These results suggested that ABCC1 is a candidate prognostic marker for ICC.