Correlation between permeability-related glycoprotein expression and susceptibility to oxygen radicals in vincristine-resistant hematologic cell lines

This study was designed to test the correlation between the expression of permeability-related glycoprotein (P-GP) and susceptibility to oxygen radicals derived from the reaction of hypoxanthine (HX)-xanthine oxidase (XO) in wild type and vincristine (VCR)-resistant hematologic cell lines. A marked correlation between P-GP expression and susceptibility to oxygen radicals was found in VCR-resistant cells, while it was weak in wild cell lines. In contrast, there was neither correlation between sensitivity to VCR and oxygen radicals nor between sensitivity to VCR and P-GP expression in both wild type and VCR-resistant cells. No correlation between sensitivity to adriamycin or oxygen radicals and P-GP expression were observed in both cells tested. These results may suggest a new mechanism of drug resistance in cells expressing P-GP.