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Overexpression of bax in human glioma cell lines
M A Vogelbaum1, J X Tong, R Perugu
1Department of Neurology and Neurological Surgery, Washington University School of Medicine, St. Louis, Missouri 63110, USA.
Object:
Cells that lose their ability to undergo apoptosis may promote the development of neoplasms and result in resistance to clinical treatment with DNA-damaging modalities such as radio- and chemotherapy. Four established human glioma cell lines that are resistant to apoptosis were transfected with the proapoptotic gene bax and assessed for their sensitivity to a proapoptotic stimulus.
Methods:
Two cell lines had a wild-type p53 genotype (U87 and D247MG) and two had mutant p53 genotypes (U138 and U373). Constitutive overexpression of murine bax was achieved in U138 and U373 only, which resulted in an increased sensitivity of these lines to the apoptosis-inducing effect of cytosine arabinoside (ara-C). Multiple attempts to produce constitutive overexpression of bax in U87 and D247MG cells resulted in spontaneous, near-complete cell loss. Vector-only control transfections were successful in all four cell lines. Inducible overexpression of bax was achieved in the U87 cells and elevated levels of BAX were observed as early as 6 hours after gene induction. This overexpression of BAX resulted in the spontaneous induction of apoptosis in these cells.
Conclusions:
Overexpression of BAX in four human glioma cell lines resulted in increased sensitivity to apoptosis. In the two lines that had a wild-type p53 genotype, overexpression of BAX produced spontaneous apoptosis. In contrast, the lines that had mutant, nonfunctional P53 did not undergo spontaneous apoptosis, but they were rendered more sensitive to the apoptosis-inducing effect of ara-C. Modulation of BAX expression may be a useful therapeutic modality for gliomas, regardless of p53 genotype.
Insights
Introducing the proapoptotic gene BAX into glioma cells enhances their sensitivity to apoptosis. This approach shows promise for treating gliomas, irrespective of p53 gene status.
Area of Science:
- Molecular biology
- Cancer research
- Genetics
Background:
- Apoptosis evasion is a hallmark of cancer, contributing to tumor development and treatment resistance.
- Glioma cells resistant to apoptosis pose significant therapeutic challenges.
- The BAX gene plays a crucial role in initiating programmed cell death.
Purpose of the Study:
- To investigate the effect of BAX gene transfection on apoptosis sensitivity in human glioma cell lines.
- To assess the role of p53 genotype in mediating BAX-induced apoptosis.
- To explore BAX as a potential therapeutic target for gliomas.
Main Methods:
- Four human glioma cell lines with varying p53 genotypes (wild-type and mutant) were used.
- Cells were transfected with the proapoptotic gene BAX, achieving constitutive or inducible overexpression.
- Apoptosis induction was assessed following BAX gene manipulation and exposure to cytosine arabinoside (ara-C).
Main Results:
- Overexpression of BAX increased apoptosis sensitivity in all tested glioma cell lines.
- Wild-type p53 glioma cells exhibited spontaneous apoptosis upon BAX induction.
- Mutant p53 glioma cells showed increased sensitivity to ara-C after BAX overexpression, but not spontaneous apoptosis.
Conclusions:
- BAX gene modulation enhances apoptosis in glioma cells, regardless of p53 status.
- Targeting BAX offers a potential therapeutic strategy for gliomas, even those with non-functional p53.
- Further research into BAX-based therapies could overcome treatment resistance in gliomas.