We investigated MDR1 activation in MDR variants of a human sarcoma line, some of which express a mutant MDR1, which facilitated the study of allelic gene expression.
In six sarcomas with mdr1 mRNA expression, five were resistant against doxorubicin and cross-resistant against several other drugs, whereas from eight sarcomas, which lacked detectable mdr1 mRNA, seven were sensitive to doxorubicin and other drugs.
In this review, an attempt is made to summarise the accuracy of the measurement of MDR1 expression for use in prognosis, as well as in decisions on chemotherapeutic treatment of sarcomas.
We studied MDR1 gene expression in 39 samples from 33 cases of soft tissue sarcomas comprising 11 liposarcomas, nine malignant fibrous histiocytomas, six leiomyosarcomas, four malignant schwannomas, three fibrosarcomas, three synovial sarcomas, and three epithelioid sarcomas, and seven cases of benign soft tissue tumors in adult patients.
Units of mdr1 expression were defined by reference to drug-sensitive human sarcoma and K562 leukemia cell lines (1 U) and the highly resistant doxorubicin selected leukemia cells K562/R7 (50 U).