Prognostic significance of ATP-binding cassette (ABC) and solute carrier (SLC) transporters in pancreatic ductal adenocarcinoma (PDAC).

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Abstract
11051 Background: Resistance against anticancer drugs significantly limits the clinical use and efficacy. One of the most important mechanisms of the multidrug resistance is low accumulation of the drug in cancer cells caused by an increased efflux (mediated mainly by ABCs) or by a decreased uptake (mediated by some members of SLCs). The aim of the present study was to investigate prognostic importance of 13 anticancer drug-relevant SLCs and all 49 human ABCs in PDAC patients in association with clinical and pathological characteristics and the tumor KRAS mutation status. Methods: Tumors and adjacent non-neoplastic pancreatic tissues were obtained from 50 patients with histologically verified PDAC. The transcript profile of ABCs and SLCs was assessed using quantitative real-time PCR. KRAS mutations in exon 2 were assessed by high-resolution melting analysis and sequencing. Associations of transcript levels with clinical parameters were assessed by non-parametric Mann-Whitney tests. The Kaplan-Meier method with the log-rank test and Cox regression were used for analysis of overall survival (OS). Results: Most transporters investigated were deregulated in PDAC and 14 ABCs or SLCs were associated with clinical characteristics. Up-regulation of 7 drug resistance-associated ABC efflux transporters and down-regulation of 5 drug uptake-relevant SLC transporters was observed in tumors vs. non-neoplastic tissues. Moreover, expression levels of SLC28A1 and SLC22A1 were associated with OS of all patients (P=0.001). High transcript levels of SLC29A3 and SLC22A3 significantly predicted longer OS in chemotherapy-treated patients (P=0.004 and P=0.038, respectively). No association of ABC and SLC expression with KRAS mutation status was observed. Conclusions: Up-regulation of numerous drug resistance-associated ABCs and down-regulation of SLCs implicated in drug uptake may explain the generally very poor response of PDAC to cytotoxic agents. This study also identified some ABCs and SLCs as potential prognostic and predictive factors in PDAC. Supported by the Czech Science Foundation grant P301/12/1734 and CZ.1.05/2.1.00/03.0076 European Regional Development Fund.
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