[Establishment of MRP-overexpression subline of bladder carcinoma and its MDR phenotype].

OBJECTIVE: To investigate MRP expression and multidrug resistance(MDR) phenotype of a bladder carcinoma subline transfected with the full length MRP cDNA. METHODS: After transfection, a stable MRP-overexpressed subline named EJ/MRP was established. Gene expression of MRP and mdr1 were detected by using RT-PCR and immunohistochemistry methods. Drug sensitivity testing of the EJ/MRP cells to 11 kinds of anti-cancer agents was examined. RESULTS: Compared with EJ/Vect which was mock transfected, MRP mRNA level of EJ/MRP increased 14.3 fold and MRP expression was mainly located in cytosol and plasma membrane. The relative resistance (RR) to VP-16, vincristine increased more than 10 fold, and that to doxorubicin, hydroxycamptothecin, thiotepa, mitomycin and cyclophosphamide increased 3 to 10 fold. CONCLUSION: Bladder carcinoma with stably over-expressed MRP presents typical MDR phenotype but without mdr1/P-gp expression. It provides a good model and positive control for the study of MRP-mediated MDR.