OBJECTIVETo detect expression of p-glycoprotein (P-gp), multidrug resistance-associated protein (MRP), and glutathione S-transferase (GST-pi), and to evaluate its clinical significance in neuroblastoma (NB).

METHODSSP immunohistochemical technique was used to investigate expression of P-gp, MRP, and GST-pi in 70 cases of NB.

RESULTSThe frequency of expression of P-gp, MRP, and GST-pi was 61.4%, 38.6%, and 51.4%, respectively. The coexpression rate of P-gp and MRP, P-gp and GST-pi, MRP and GST-pi, P-gp, MRP and GST-pi was 32.9%, 35.7%, 27.1%, and 24.3%, respectively. Significant positive correlation was observed between P-gp and MRP expression (P = 0.001), and between MRP and GST-pi expression (P = 0.012), but no correlation was found between P-gp and GST-pi expression. The expression of P-gp and MRP was higher in tumors from patients over 1 year old compared with those less than 1 year old at diagnosis (P = 0.01, 0.018, respectively). MRP expression was higher in tumors from the metastatic than the non metastatic groups (P = 0.015). All tested proteins showed significant relationship to the differentiation of the tumor (P = 0.006, 0.000, 0.019, respectively), but no correlation was found to the stage of NB or sex of the patients. MRP expression was significantly related to the reduction of both median survival time and the two-year cumulative survival (P = 0.02). In contrast, P-gp and GST-pi expression had no correlation with survival.

CONCLUSIONSThe intrinsic multidrug resistance of NB involves the combined effects of P-gp, MRP, and GST-pi. MRP expression may be an important parameter in predicting the prognosis of patients with NB.