Effect of various chemosensitizers on chemoresistance to adriamycin in MIP - 101 cell line, a colon carcinoma cell line: analysis of glutathione and related enzymes

We evaluated the multidrug resistance modulating effect of verapamil, buthionine sulfoximine, trifluoperazine and tamoxifen in a human colorectal cell line resistant de novo to adriamycin. We studied the effect of these chemosensitizers on glutathione content, glutathione reductase, transferases, peroxidases, γ-glutamyl transpeptidase and glucose-6-phosphate dehydrogenase activities. The ratio of the activities between resistant and sensitive cells treated by these compounds as compared with the ratio of the untreated cells decreases, thus contributing to the reversal of chemoresistance. This study implies a role of glutathione and related enzymes in chemoresistance to adriamycin, although this is certainly not the sole mechanism.