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Cytochrome P450 reductase, antioxidant enzymes and cellular resistance to doxorubicin
S V Singh1, J Iqbal, A Krishan
1Department of Oncology, University of Miami School of Medicine, FL 33136.
Abstract:
Our data suggest that DOX resistance in P388/R-84 cells may result, at least in part, from reduced free radical formation by both suppression of flavin reductase(s) and overexpression of certain antioxidant enzymes such as GSH peroxidase and catalase. In addition, our results, in conjunction with other studies, indicate that flavin reductase(s) and antioxidant enzymes are differentially altered in cancer cells with acquired or de novo resistance to DOX. Further studies are needed, however, to elucidate the mechanism(s) by which the gene expression of these enzymes is regulated in drug-sensitive and -resistant cells.
Insights
Doxorubicin resistance in cancer cells may stem from lower free radical production due to suppressed flavin reductases and increased antioxidant enzymes like GSH peroxidase and catalase. These enzyme alterations are key in drug resistance.
Area of Science:
- Biochemistry
- Molecular Biology
- Cancer Research
Background:
- Doxorubicin (DOX) is a widely used chemotherapy agent.
- Acquired resistance to DOX is a significant clinical challenge.
- The mechanisms underlying DOX resistance are not fully understood.
Purpose of the Study:
- To investigate the role of free radical formation in DOX resistance.
- To examine the involvement of flavin reductases and antioxidant enzymes in DOX-resistant cells.
- To identify potential targets for overcoming DOX resistance.
Main Methods:
- Cell culture of DOX-sensitive (P388) and DOX-resistant (P388/R-84) cell lines.
- Measurement of free radical formation.
- Assay of flavin reductase activity.
- Quantification of antioxidant enzyme expression (GSH peroxidase, catalase).
Main Results:
- DOX-resistant cells exhibited reduced free radical formation compared to sensitive cells.
- Suppression of flavin reductase activity was observed in resistant cells.
- Overexpression of antioxidant enzymes, including GSH peroxidase and catalase, was detected in resistant cells.
- Differential alterations in flavin reductase(s) and antioxidant enzymes were noted in DOX-resistant cells.
Conclusions:
- Reduced free radical formation, mediated by suppressed flavin reductases and enhanced antioxidant enzymes, contributes to DOX resistance.
- Flavin reductases and antioxidant enzymes are differentially regulated in cancer cells with acquired or de novo DOX resistance.
- Further research is required to elucidate the regulatory mechanisms of these enzymes in drug-sensitive and resistant cells.