BACKGROUNDDrug-resistance of tumor is the main reason of the failure of che-motherapy. Much attention has been paid to the expression of multidrug resistance-associated protein (MRP) and its mechanism of drug-resistance in non-small cell lung cancer (NSCLC). Results of this research will contribute to reversing drug-resistance and improving curative effect. The aim of this study is to investigate the relationships between the expression of MRP and clinicopathological parameters and prognosis in patients with NSCLC.

METHODSExpression of MRP was detected in 62 cases of paraffin-embedded NSCLC samples by streptavidin-biotin-peroxidase complex immunohistochemistry method, as well as in 30 fresh cases of NSCLC samples and corresponding normal lung tissues by immunohistochemistry and Western blot.

RESULTSMRP expression of NSCLC tissues was significantly higher than that of normal lung tissues. The survival time of patients with negative MRP expression was (69.81±17.41) months, and that of patients with positive MPR expression was (25.38±4.46) months (P=0.0156). This statistically significant relationship between the survival time and prognosis was also showed in squamous cell carcinoma patients (P=0.015), but not in adenocarcinoma. Multivariate COX model analysis suggested that the survival time was significantly related to lymphatic metastasis (P=0.038) and expression of MRP (P=0.035).

CONCLUSIONSMRP expression in NSCLC is significantly higher than that in the normal lung tissues. The mean survival time of patients with negative MRP expression is remarkably longer than that of patients with positive MRP expression. MRP expression may be an independent prognostic factor.