The importance of DT-diaphorase in mitomycin C resistance in human colon cancer cell lines.

Abstract

BACKGROUND:

Prior studies have suggested the multifactorial nature of mitomycin C (MMC) resistance. However, the relative importance of the different resistance mechanisms is unknown.

MATERIALS AND METHODS:

A panel of colon cancer cell lines with levels of MMC resistance from 2- to 15-fold compared to the parent line HT-29 was produced by repeated MMC exposure. Cell survival was measured using clonogenic assay. Glutathione and related enzymes and DT-diaphorase were measured using biochemical assays. P-glycoprotein expression was measured using flow cytometry. Topoisomerase II activity was measured using the pBR322 DNA relaxation assay.

RESULTS:

Multiple drug resistance mechanisms were altered in the resistant cell lines (glutathione reductase, glutathione peroxidase, topoisomerase II). However, the level of DT-diaphorase correlated best with the degree of MMC resistance. The importance of DT-diaphorase was confirmed by using BMY 25282, an MMC analogue which is less dependent on DT-diaphorase for activation. Resistance in the HT-29R54 cell line was 15-fold with MMC compared to 5-fold with BMY 25282. P-glycoprotein-mediated resistance does not appear important in this model.

CONCLUSIONS:

Although MMC resistance appears to be multifactorial, the results of this study strongly suggest that DT-diaphorase is the major contributor to MMC resistance under aerobic conditions. Strategies to enhance drug activation may therefore be useful for reversing MMC resistance.

• Authors: P A Lambert, Y Kang, B Greaves, R R Perry
• Journal: The Journal of surgical research (J Surg Res) Vol. 80 Issue 2 Pg. 177-81 (Dec 1998) ISSN: 0022-4804 [Print] United States
• PMID: 9878310 (Publication Type: Journal Article)
• Copyright: Copyright 1998 Academic Press.

Chemical References

• ATP Binding Cassette Transporter, Subfamily B, Member 1
• Antibiotics, Antineoplastic
• Mitomycins
• Mitomycin
• N(6)-((dimethylamino)methylene)mitomycin C
• Glutathione Peroxidase
• NAD(P)H Dehydrogenase (Quinone)
• Glutathione Reductase
• DNA Topoisomerases, Type II
• Glutathione

Topics

• ATP Binding Cassette Transporter, Subfamily B, Member 1 (metabolism)
• Aerobiosis
• Antibiotics, Antineoplastic (metabolism, pharmacology)
• Cell Survival (drug effects)
• Colonic Neoplasms (drug therapy, enzymology, pathology)
• DNA Topoisomerases, Type II (metabolism)
• Drug Resistance
• Drug Resistance, Multiple
• Glutathione (metabolism)
• Glutathione Peroxidase (metabolism)
• Glutathione Reductase (metabolism)
• Humans
• Mitomycin (metabolism, pharmacology)
• Mitomycins
• NAD(P)H Dehydrogenase (Quinone) (metabolism)
• Oxidation-Reduction
• Tumor Cells, Cultured
• Tumor Stem Cell Assay