Suppression of apoptosis by overexpression of Bcl-2 or Bcl-xL promotes survival and mutagenesis after oxidative damage

Apoptosis is the physiological process by which unwanted cells in an organism are killed. Bcl-2, a membrane-bound cytoplasmic protein, and its close relative Bcl-X-L, are both effective inhibitors of apoptosis induced by a wide variety of stimuli in many different cell types. In a previous study, we reported that suppression of apoptosis by BCl-2 or Bcl-X-L, markedly elevates the levels of radiation-induced mutations at the specific locus thymidine kinase. We investigated the effect of the Bcl-2 or Bcl-X-L overproduction on hydrogen peroxide-induced mutagenesis. Oxidative DNA damage has been implicated in biological processes such as mutagenesis, carcinogenesis and aging. Overexpression of either Bcl-2 or Bcl-X-L enhances oxidative stress mutagenesis in cells with wild type p53 as well as with mutated p53 protein. These results support the hypothesis that apoptosis plays a crucial role in maintaining genomic integrity by selectively eliminating highly mutated cells from the population.