Prognostic value of MRP, LRP and P-gp in patients with non-small cell lung cancer

The aim of this study was to investigate the prognostic value of glutathione-S-transferase p1 (GST-p), multidrug resistance proteins (MRP), lung resistance-related protein (LRP), P-glycoprotein (P-gp) and topoisomerase 2 expression (Topo IIα) in patients with non-small cell lung cancer (NSCLC) treated with platinum-based chemotherapy. Expression of GST-p, MRP, LRP, P-gp and Topo IIα were conducted using immunohistochemistry. Chi-Square, Kaplan-Meier, Log-rank test and multivariate Cox's regression analysis were used to detect the correlation of proteins, clinicopathological characteristics and survivals. MRP and P-gp were associated with tumor differentiation, respectively (MRP: P=0.020; P-gp: P=0.030), LRP was associated with tumor type (P < 0.001), regional lymph node metastasis (P=0.014) and tumor stage (P=0.032). No significant association was observed between clinical features and GST-p and Topo IIα (P > 0.05). Poor survivals were markedly correlated with higher expression of MRP, LRP or P-gp, respectively. Besides, combination of MRP, LRP and P-gp had a better predictive value compare with single marker. No significant difference was observed between GST-p or Topo IIα and survival time. MRP and P-gp were observed as independent prognostic factors. This is the first report P-gp overexpression is associated with poor survival in NSCLC, furthermore, this is the first study to evaluate the combination predictive value of MRP, LRP and P-gp in NSCLC. Our findings suggest combination of MRP, LRP and P-gp are more useful predictors in NSCLC patients treated with platinum-based chemotherapy.