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Array-based comparative gene expression analysis of tumor cells with increased apoptosis resistance after hypoxic
Martin Weinmann1, Claus Belka, Dilek Güner
1Department of Radiation Oncology, University of Tuebingen, Germany.
Oncogene
|May 18, 2005
Summary
Cyclic hypoxia selects for tumor cells resistant to cancer therapies like doxorubicin and radiation. This adaptation involves complex gene expression changes, impacting stress resistance and anti-apoptotic signaling.
Area of Science:
- Oncology
- Molecular Biology
- Cellular Biology
Background:
- Tumor hypoxia is a negative prognostic indicator in cancer.
- Cyclic hypoxia can select for tumor cells with cross-resistance to mitochondrial death pathways.
- Sensitivity to death-receptor ligands is generally unaffected by cyclic hypoxia.
Purpose of the Study:
- To investigate cellular alterations induced by cyclic hypoxia.
- To identify gene expression pattern changes following hypoxic selection using DNA microarrays.
Main Methods:
- Exposure of tumor cells to cyclic hypoxia.
- DNA-microarray analysis to assess gene expression profiles.
- Assessment of cellular resistance to doxorubicin and radiation.
Main Results:
- Cyclic hypoxia selected for cells resistant to doxorubicin and radiation.
- Hypoxic selection led to constitutive gene expression changes: 156 genes downregulated, 82 genes upregulated.
- Differentially regulated genes were primarily involved in cellular responses to hypoxia and reoxygenation.
- Upregulated genes were associated with stress resistance and anti-apoptotic signaling.
- Hypoxic selection induced broad gene expression alterations, indicating a complex adaptation process rather than changes in single apoptosis-related genes.
Conclusions:
- Cyclic hypoxia promotes tumor cell adaptation and resistance to therapy.
- Gene expression profiling reveals a complex adaptive response to cyclic hypoxia.
- Understanding these adaptations is crucial for developing novel cancer treatment strategies.