EXPRESSION OF MRP AND MDR1 IN HUMAN GASTROINTESTINAL CANCER CELL-LINES - A CORRELATION WITH RESISTANCE AGAINST DOXORUBICIN

The mRNA expression of mdr1 and MRP, each of which codes for a transpo rt protein belonging to ATP-binding cassette superfamily and are repor ted to be responsible for multidrug resistance phenotype, were semiqua ntified by RT-PCR in a panel of gastrointestinal cancer cell lines. Al though the expression of MRP was predominant in esophageal cancer cell lines, expression of either or both of the genes was detected in all the cell lines tested. Expression of these two genes added together co rrelated significantly with chemosensitivity against doxorubicin, impl icating that expression of both genes should be evaluated in the futur e analysis of multidrug resistance phenotype. The ID50 values for pira rubicin, although generally lower than the values for doxorubicin, cor related well with the latter, suggesting that the similar phenotype as that for doxorubicin might be responsible for drug resistance against this semisynthetic anthracycline glycoside. (C) 1996 Wiley-Liss, Inc.