Journal Article

Bcl-2 over-expression promotes genomic instability by inhibiting apoptosis of cells exposed to hydrogen peroxide

Andrew G. Cox and Mark B. Hampton

in Carcinogenesis

Volume 28, issue 10, pages 2166-2171
Published in print October 2007 | ISSN: 0143-3334
Published online April 2007 | e-ISSN: 1460-2180 | DOI: http://dx.doi.org/10.1093/carcin/bgm093
Bcl-2 over-expression promotes genomic instability by inhibiting apoptosis of cells exposed to hydrogen peroxide

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The anti-apoptotic oncogene bcl-2 is hypothesized to increase the antioxidant status of cells, thereby protecting them from oxidative stress. In this study, we examined hydrogen peroxide (H2O2)-mediated oxidative stress in Jurkat T lymphoma cells. Over-expression of Bcl-2 did not inhibit cytotoxicity at doses of H2O2 that caused necrosis (>200 μM), but it did block cell death at apoptotic doses (<200 μM). However, these cells exhibited the same initial level of protein and lipid oxidation following exposure to H2O2 as the parental cells, indicating that the anti-apoptotic activity is not associated with general antioxidant properties. Bcl-2 expression was able to protect against secondary protein carbonyl formation, which was linked to lysosome stabilization. Assessment of micronuclei formation in cells over-expressing Bcl-2 showed evidence of increased genomic instability, consistent with the impairment of apoptosis in damaged cells. We conclude that while Bcl-2 can block cytotoxicity associated with apoptosis-inducing levels of oxidative stress, it does not protect the cells from the stress itself. Bcl-2 may promote tumourigenesis by preventing the removal of oxidatively damaged cells.

Journal Article.  4275 words.  Illustrated.

Subjects: Clinical Cytogenetics and Molecular Genetics

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