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Chronic exposure to the cytolethal distending toxins of G ram‐negative bacteria promotes genomic instability and altered DNA damage response
Author(s) -
Guidi Riccardo,
Guerra Lina,
Levi Laura,
Stenerlöw Bo,
Fox James G.,
Josenhans Christine,
Masucci Maria G.,
Frisan Teresa
Publication year - 2013
Publication title -
cellular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.542
H-Index - 138
eISSN - 1462-5822
pISSN - 1462-5814
DOI - 10.1111/cmi.12034
Subject(s) - biology , genome instability , dna damage , cytolethal distending toxin , dna repair , sos response , cell cycle , senescence , malignant transformation , genomic dna , cell , microbiology and biotechnology , cancer research , genetics , bacteria , dna , microbial toxins
Summary Epidemiological evidence links chronic bacterial infections to the increased incidence of certain types of cancer but the molecular mechanisms by which bacteria contribute to tumour initiation and progression are still poorly characterized. Here we show that chronic exposure to the genotoxin cytolethal distending toxin ( CDT ) of G ram‐negative bacteria promotes genomic instability and acquisition of phenotypic properties of malignancy in fibroblasts and colon epithelial cells. Cells grown for more than 30 weeks in the presence of sublethal doses of CDT showed increased mutation frequency, and accumulation of chromatin and chromosomal aberrations in the absence of significant alterations of cell cycle distribution, decreased viability or senescence. Cell survival was dependent on sustained activity of the p38 MAP kinase. The ongoing genomic instability was associated with impaired activation of the DNA damage response and failure to efficiently activate cell cycle checkpoints upon exposure to genotoxic stress. Independently selected sublines showedenhanced anchorage‐independent growth as assessed by the formation of colonies in semisolid agarose. These findings support the notion that chronic infection by CDT ‐producing bacteria may promote malignant transformation, and point to the impairment of cellular control mechanisms associated with the detection and repair of DNA damage as critical events in the process.

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