Background
Expression profile of drug transporters may contribute to the low response rate to systemic chemotherapy in patients with pancreatic ductal adenocarcinoma (PDAC). The aim of our study was evaluate prognostic significance of multidrug resistance-associated ATP-binding cassette (ABC) and solute carrier (SLC) transporters in patients who underwent pancreas resection for PDAC.

Materials and Methods
Transcript profile of 15 drug efflux ABC and 13 drug influx SLC transporter genes was measured by real-time PCR in tumors and adjacent non-neoplastic pancreatic tissues in 32 patients. Associations of expressions of individual genes, gene combinations and overall survival (OS) of patients were evaluated.

Result
Seven ABC transporters were significantly overexpressed in tumors compared to non-neoplastic tissues and 5 of 10 SLC transporters were downregulated in tumors. High level of ABCC1 was significantly associated with longer OS. In contrast, high levels of ABCC2, ABCC4, SLC22A1 or SLC28A1 were associated with shorter OS. In a subgroup of chemotherapy-treated patients (n=19), high levels of ABCB4, ABCC1, ABCG2, SLC22A3 or SLC29A3 were associated with longer OS. Patients with combination of low expression of SLC22A3 and high expression of ABCC2 had significantly shorter OS compared to the rest of chemotherapy-treated patients (P<0.001).

Conclusion
Our study shows that expression of ABC and SLC transporters has an influence on survival of patients with PDAC. Intratumoral downregulation of multiple drug influx SLC and overexpression of drug efflux ABC transporters supports the concept that drug transporters are at least in part responsible for low chemosensitivity of patients with PDAC.