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The decrease of mitochondrial NADH dehydrogenease and drug induced apoptosis in doxorubicin resistant A431 cells
1Department of Biochemistry, The Chinese University of Hong Kong, Shatin.
Abstract:
Doxorubicin (DOX) resistant A10A cells derived from human squamous carcinoma A431 cells were found to exhibit a smaller degree of apoptosis after DOX treatment as compared to their parent cells. Induction of reactive oxygen species (ROS) formation and mitochondrial depolarization by DOX were more pronounced in the parent cells than in the A10A cells. The fact that catalase suppressed the DOX effect on ROS induction, mitochondrial depolarization and apoptosis in both cell lines suggests an involvement of ROS in the DOX-induced apoptosis. To investigate the underlying mechanisms for DOX resistance in A10A cells, RT-PCR based differential display was used. One of the clones, which was down-regulated in the A10A cells, had sequence homology with part of the mitochondrial NADH dehydrogenase III (ND3) gene. NADH dehydrogenase plays an important role in generating ROS during DOX treatment. The results indicate that down-regulation of ND3 may at least in part contribute to the mechanism for A10A cells resistant to DOX-induced apoptosis.
Insights
Doxorubicin resistance in A10A cells is linked to reduced apoptosis and lower reactive oxygen species (ROS) generation. Down-regulation of mitochondrial NADH dehydrogenase III (ND3) may explain this resistance mechanism.
Area of Science:
- Cell Biology
- Molecular Oncology
- Biochemistry
Background:
- Doxorubicin (DOX) is a chemotherapy drug that induces apoptosis.
- Acquired resistance to DOX is a significant clinical challenge.
- Understanding resistance mechanisms is crucial for improving cancer therapy.
Purpose of the Study:
- To investigate the mechanisms of Doxorubicin resistance in A10A cells, a human squamous carcinoma cell line.
- To identify molecular factors contributing to reduced apoptosis and altered cellular responses to DOX.
Main Methods:
- Comparative analysis of apoptosis induction by DOX in parent A431 cells and DOX-resistant A10A cells.
- Assessment of reactive oxygen species (ROS) generation and mitochondrial depolarization.
- RT-PCR based differential display to identify differentially expressed genes.
- Sequence homology analysis of identified clones.
Main Results:
- A10A cells showed significantly less apoptosis following DOX treatment compared to parent cells.
- DOX-induced ROS formation and mitochondrial depolarization were less pronounced in A10A cells.
- Catalase partially reversed DOX effects, confirming ROS involvement in apoptosis.
- Differential display identified a down-regulated clone with homology to mitochondrial NADH dehydrogenase III (ND3) gene in A10A cells.
Conclusions:
- Reduced apoptosis and ROS generation contribute to DOX resistance in A10A cells.
- Down-regulation of the mitochondrial ND3 gene may be a key factor in DOX resistance.
- Targeting ND3 or related pathways could offer strategies to overcome DOX resistance.