MDR1/P-glycoprotein and MRP-1 mRNA and protein expression in non-small cell lung cancer

Background: Multiple drug resistance (MDR), both inherent and acquired, is a serious problem in non-small cell lung carcinomas (NSCLC). The purpose of this study was to investigate the prevalence of expression of genes encoding drug efflux pumps, MDR1 and MRP-1, at both the mRNA and protein levels, in this type of cancer. Materials and Methods: Tumour specimens (38 cases) were analysed using immunohistochemistry and, where possible (30 cases), also using reverse-transcriptase polymerase chain reaction. Results: The results from this analysis indicated that either, or both, drug efflux pumps were frequently expressed in NSCLC. Expression of mrpl was found to be predominant over mdr1 at the mRNA level, while MDR1 P-gp was more frequently detected than MRP-1 protein. In some cases, proteins encoding pumps were detected without corresponding mRNAs - possibly due to differing sensitivities of the analysis techniques. Conclusion: Future studies of mdrl and mrp1 using increasedsensitivity qPCR techniques, in parallel with protein analysis, in larger cohorts of cases may help to elucidate the role of drug efflux pumps in NSCLC multiple drug resistance.