kiny
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http://www.infectagentscancer.com/content/pdf/1750-9378-9-2.pdf
Infectious Agents and Cancer
10 January 2014
Adherent-invasive E. colistrain LF82 is associated with Crohn’s disease [36], which can lead to colon cancer later in life [64,65]. Strain LF82 and other AIEC bacteria are considered pathobionts, which are commensal bacteria that can lead to disease. Consistent with a possible role for LF82 in carcinogenesis, we found that OMVs derived from E. coli
strain LF82 induced DNA damage, 8-oxo-dG adducts, DNA rereplication, and aneuploidy. As AIEC can colonise the gut and hence can reside in the intestine for considerable periods, the ability of their OMVs to induce ROS and DNA damage suggest that LF82 is, potentially, a significant risk for genotoxic damage within the gut.
Background
Colorectal cancers are the third most common type in the world. The causes of the disease are poorly understood, but since the discovery of Helicobacter pylori as a causative agent of gastric cancer, attention has turned to bacteria as a possible trigger for colorectal cancer.
Recently H. pylori outer membrane vesicles (OMVs) were revealed as potentially genotoxicwhich can be important first step in carcinogenesis. We therefore investigated whether OMVs from intestinal Escherichia coli could be genotoxic.
Methods
OMVs from the avirulent DH5 α strain, a pathogenic adherent-invasive E. coli
(AIEC) and an enterohaemolytic (EHEC) strain of E. coli were enriched by ultracentrifugation. The effect on the growth and viability of human enterocyte-like Caco-2 cells by OMVs was determined by trypan blue exclusion, MTT and BrdU incorporation assays. The ability of OMVs to induce
DNA damage was assayed by single-cell gel electrophoresis , and 8-oxo-dG and γH2Ax immunofluorescence staining. Cytopathological changes were assessedby microscopy. The induction of aneuploidy by the OMVs was measured by flow cytometry in Caco-2 and LoVo cells.
Results
We found that OMVs derived were internalised by Caco-2 cells,
increased cell numbers, induced double-stranded DNA breaks, recruited
γH2Ax to the nucleus, initiated DNA rereplication, and produced distended multinucleate cells. DH5 α and AIEC OMVs caused free radical generation as indicated by the reduction of glutathione in cells, leading to the development of mutagenic 8-oxo-dG adducts in DNA. Flow cytometry revealed that DH5
αand EHEC OMVs increased aneuploidy in p53 mutant Caco-2 cells, but not in
p53 wild type LoVo cells.
Infectious Agents and Cancer
10 January 2014
Adherent-invasive E. colistrain LF82 is associated with Crohn’s disease [36], which can lead to colon cancer later in life [64,65]. Strain LF82 and other AIEC bacteria are considered pathobionts, which are commensal bacteria that can lead to disease. Consistent with a possible role for LF82 in carcinogenesis, we found that OMVs derived from E. coli
strain LF82 induced DNA damage, 8-oxo-dG adducts, DNA rereplication, and aneuploidy. As AIEC can colonise the gut and hence can reside in the intestine for considerable periods, the ability of their OMVs to induce ROS and DNA damage suggest that LF82 is, potentially, a significant risk for genotoxic damage within the gut.
Background
Colorectal cancers are the third most common type in the world. The causes of the disease are poorly understood, but since the discovery of Helicobacter pylori as a causative agent of gastric cancer, attention has turned to bacteria as a possible trigger for colorectal cancer.
Recently H. pylori outer membrane vesicles (OMVs) were revealed as potentially genotoxicwhich can be important first step in carcinogenesis. We therefore investigated whether OMVs from intestinal Escherichia coli could be genotoxic.
Methods
OMVs from the avirulent DH5 α strain, a pathogenic adherent-invasive E. coli
(AIEC) and an enterohaemolytic (EHEC) strain of E. coli were enriched by ultracentrifugation. The effect on the growth and viability of human enterocyte-like Caco-2 cells by OMVs was determined by trypan blue exclusion, MTT and BrdU incorporation assays. The ability of OMVs to induce
DNA damage was assayed by single-cell gel electrophoresis , and 8-oxo-dG and γH2Ax immunofluorescence staining. Cytopathological changes were assessedby microscopy. The induction of aneuploidy by the OMVs was measured by flow cytometry in Caco-2 and LoVo cells.
Results
We found that OMVs derived were internalised by Caco-2 cells,
increased cell numbers, induced double-stranded DNA breaks, recruited
γH2Ax to the nucleus, initiated DNA rereplication, and produced distended multinucleate cells. DH5 α and AIEC OMVs caused free radical generation as indicated by the reduction of glutathione in cells, leading to the development of mutagenic 8-oxo-dG adducts in DNA. Flow cytometry revealed that DH5
αand EHEC OMVs increased aneuploidy in p53 mutant Caco-2 cells, but not in
p53 wild type LoVo cells.
