EXPRESSION OF MULTIDRUG-RESISTANCE ASSOCIATED PROTEIN GENE IN HUMAN SOFT-TISSUE SARCOMAS

We examined the mRNA expression of the multidrug-resistance-associated protein gene (MRP) in soft-tissue sarcomas and compared it with the e xpression of the multidrug resistance gene (MDR1), using the reverse t ranscriptase/polymerase chain reaction. We investigated 39 samples fro m 33 cases of soft-tissue sarcomas (11 liposarcomas, 9 malignant fibro us histiocytomas, 6 leiomyosarcomas, 4 malignant schwannomas, 3 fibros arcomas, 3 synovial sarcomas, and 3 epithelioid sarcomas) and 7 benign soft-tissue tumors. All samples were obtained prior to chemotherapy. An expression of MRP mRNA was noted in 56% of soft-tissue sarcoma spec imens. The co-expression of MRP and MDR1 was recognized in 15 samples (38%) (5/11 liposarcomas, 5/9 malignant fibrous histiocytomas, 3/6 lei omyosarcomas, 2/3 fibrosarcomas) and significantly correlated with his tological grade (P = 0.0165). A positive and signifrcant correlation w as found between MRP and MDR1 expression in soft-tissue sarcomas (P = 0.0013). In benign soft-tissue tumors, 1 chemodectoma and 1 neurotheke oma showed low MRP expression; however, no case showed co-expression o f MRP and MDR1.