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Hypoxia-mediated selection of cells with diminished apoptotic potential in solid tumours
T G Graeber1, C Osmanian, T Jacks
1Department of Radiation Oncology, Stanford University School of Medicine, California 94305, USA.
Nature
|January 4, 1996
Summary
Hypoxia, or low oxygen, triggers programmed cell death (apoptosis) in cancer cells. Genetic changes, like p53 mutations, allow cancer cells to evade this death, promoting tumor growth.
Area of Science:
- Oncology
- Cell Biology
- Genetics
Background:
- Apoptosis, a programmed cell death, acts as a tumor suppressor.
- Solid tumors often exhibit hypoxia (low oxygen) and necrosis.
- Hypoxia and apoptosis are critical in tumor development and progression.
Purpose of the Study:
- To investigate the role of hypoxia in inducing apoptosis in cancer cells.
- To determine how genetic alterations affect hypoxia-induced apoptosis.
- To explore the selective pressure of hypoxia on cancer cells with defective apoptosis.
Main Methods:
- Utilizing oncogenically transformed cells.
- Analyzing the impact of p53 tumor-suppressor gene status and Bcl-2 expression.
- Employing transplanted tumor models in vivo.
- Correlating hypoxic regions with apoptotic activity in tumors.
Main Results:
- Hypoxia induces apoptosis in transformed cells.
- Loss of p53 or overexpression of Bcl-2 significantly reduces hypoxia-induced cell death.
- Hypoxia selects for transformed cells with impaired apoptosis, particularly those lacking p53.
- Apoptosis strongly correlates with hypoxia in p53-wild-type tumors but not in p53-deficient tumors.
Conclusions:
- Hypoxia acts as a selective pressure favoring the expansion of cancer cells with reduced apoptotic potential.
- Acquisition of p53 mutations is a key mechanism for tumor cells to survive hypoxic conditions.
- Understanding the interplay between hypoxia and apoptosis is crucial for cancer therapy development.