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Superoxide anion inhibits drug-induced tumor cell death
S Pervaiz1, J K Ramalingam, J L Hirpara
1Department of Physiology, National University of Singapore, Singapore.
Abstract:
Intracellular superoxide (O(2)*- was manipulated in M14 melanoma cells by overexpression or repression of Cu/Zn SOD using a tetracycline-inducible expression system. Scavenging intracellular O(2)*- increased tumor cell sensitivity to daunorubicin, etoposide, and pMC540, whereas expression of the antisense SOD mRNA significantly decreased cell sensitivity to drug treatment. Whereas Cu/Zn SOD overexpressing cells exhibited higher activation of the executioner caspase 3 upon drug exposure, caspase 3 activation was significantly lower when Cu/Zn SOD was repressed by antisense expression. These data show that intracellular O(2)*- regulates tumor cell response to drug-induced cell death via a direct or indirect effect on the caspase activation pathway.
Insights
Intracellular superoxide regulates cancer cell drug response. Manipulating superoxide levels via Cu/Zn SOD affects tumor cell sensitivity to chemotherapy and apoptosis pathways.
Area of Science:
- Biochemistry
- Cell Biology
- Oncology
Background:
- Intracellular superoxide (O(2)*-) is a key reactive oxygen species.
- Superoxide dismutase (SOD) enzymes, particularly copper-zinc SOD (Cu/Zn SOD), play a critical role in managing oxidative stress.
- Understanding the role of O(2)*- in cancer drug resistance is crucial for developing effective treatments.
Purpose of the Study:
- To investigate the role of intracellular O(2)*- in modulating the sensitivity of M14 melanoma cells to chemotherapy drugs.
- To elucidate the relationship between Cu/Zn SOD expression levels and drug-induced apoptosis.
Main Methods:
- Utilized a tetracycline-inducible expression system to manipulate Cu/Zn SOD levels in M14 melanoma cells.
- Overexpressed and repressed Cu/Zn SOD using sense and antisense mRNA strategies, respectively.
- Assessed tumor cell sensitivity to daunorubicin, etoposide, and pMC540.
- Measured caspase 3 activation as an indicator of apoptosis.
Main Results:
- Scavenging intracellular O(2)*- (via Cu/Zn SOD overexpression) enhanced melanoma cell sensitivity to chemotherapeutic agents.
- Repressing Cu/Zn SOD expression with antisense mRNA significantly decreased cell sensitivity to drug treatment.
- Cu/Zn SOD overexpressing cells showed increased caspase 3 activation upon drug exposure.
- Repressed Cu/Zn SOD cells exhibited significantly lower caspase 3 activation.
Conclusions:
- Intracellular O(2)*- levels directly influence tumor cell response to drug-induced cell death.
- Cu/Zn SOD activity modulates cancer cell sensitivity to chemotherapy by affecting the caspase activation pathway.
- Targeting intracellular O(2)*- may represent a novel strategy to overcome drug resistance in melanoma.