title: Enterococcus faecalis infection causes inflammation, intracellular oxphos-independent ROS production, and DNA damage in human gastric cancer cells.
abstract: BACKGROUND
  Achlorhydria caused by e.g. atrophic gastritis allows for bacterial overgrowth, which induces chronic inflammation and damage to the mucosal cells of infected individuals driving gastric malignancies and cancer. Enterococcus faecalis (E. faecalis) can colonize achlohydric stomachs and we therefore wanted to study the impact of E. faecalis infection on inflammatory response, reactive oxygen species (ROS) formation, mitochondrial respiration, and mitochondrial genetic stability in gastric mucosal cells.
  
  
  METHODS
  To separate the changes induced by bacteria from those of the inflammatory cells we established an in vitro E. faecalis infection model system using the gastric carcinoma cell line MKN74. Total ROS and superoxide was measured by fluorescence microscopy. Cellular oxygen consumption was characterized non-invasively using XF24 microplate based respirometry. Gene expression was examined by microarray, and response pathways were identified by Gene Set Analysis (GSA). Selected gene transcripts were verified by quantitative real-time polymerase chain reaction (qRT-PCR). Mitochondrial mutations were determined by sequencing.
  
  
  RESULTS
  Infection of MKN74 cells with E. faecalis induced intracellular ROS production through a pathway independent of oxidative phosphorylation (oxphos). Furthermore, E. faecalis infection induced mitochondrial DNA instability. Following infection, genes coding for inflammatory response proteins were transcriptionally up-regulated while DNA damage repair and cell cycle control genes were down-regulated. Cell growth slowed down when infected with viable E. faecalis and responded in a dose dependent manner to E. faecalis lysate.
  
  
  CONCLUSIONS
  Infection by E. faecalis induced an oxphos-independent intracellular ROS response and damaged the mitochondrial genome in gastric cell culture. Finally the bacteria induced an NF-κB inflammatory response as well as impaired DNA damage response and cell cycle control gene expression.
  Array Express accession number E-MEXP-3496.
authors: Center for Genomic Medicine, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark.
authors: Jesper A B
authors: JA
authors: Strickertsson
authors: Claus
authors: C
authors: Desler
authors: Tomas
authors: T
authors: Martin-Bertelsen
authors: Ana Manuel Dantas
authors: AM
authors: Machado
authors: Torkel
authors: T
authors: Wadstrøm
authors: Ole
authors: O
authors: Winther
authors: Lene Juel
authors: LJ
authors: Rasmussen
authors: Lennart
authors: L
authors: Friis-Hansen
mesh_terms: D002453:Cell Cycle / Q000235:genetics; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D016000:Cluster Analysis; D004249:DNA Damage; D004260:DNA Repair; D013293:Enterococcus faecalis; D005753:Gastric Mucosa / Q000378:metabolism / Q000382:microbiology / Q000473:pathology; D020869:Gene Expression Profiling; D015972:Gene Expression Regulation, Neoplastic; D016908:Gram-Positive Bacterial Infections / Q000150:complications*; D006801:Humans; D007249:Inflammation / Q000235:genetics / Q000378:metabolism / Q000382:microbiology; D042541:Intracellular Space / Q000378:metabolism; D008928:Mitochondria / Q000235:genetics / Q000378:metabolism; D008954:Models, Biological; D016328:NF-kappa B / Q000378:metabolism; D010085:Oxidative Phosphorylation; D017382:Reactive Oxygen Species / Q000378:metabolism*; D015398:Signal Transduction; D013274:Stomach Neoplasms / Q000150:complications / Q000235:genetics* / Q000378:metabolism*; D013481:Superoxides / Q000378:metabolism
chemical_list: D016328:NF-kappa B; D017382:Reactive Oxygen Species; D013481:Superoxides
references: Cancer Res. 1990 Aug 1;50(15):4737-40
references: 2369748
references: Exp Gerontol. 2005 Apr;40(4):353-7
references: 15820617
references: CA Cancer J Clin. 2005 Mar-Apr;55(2):74-108
references: 15761078
references: Infect Immun. 2007 Aug;75(8):4030-9
references: 17562777
references: N Engl J Med. 2001 Sep 13;345(11):784-9
references: 11556297
references: Redox Rep. 2011;16(1):1-7
references: 21605492
references: Mol Cancer. 2002 Dec 09;1:9
references: 12513701
references: Nature. 2006 Jul 27;442(7101):461-5
references: 16688182
references: Methods Mol Biol. 2000;132:365-86
references: 10547847
references: Genes Chromosomes Cancer. 2001 Oct;32(2):136-43
references: 11550281
references: Scand J Clin Lab Invest. 2006;66(7):607-21
references: 17101553
references: Gastroenterology. 2006 Jul;131(1):246-58
references: 16831607
references: Bioinformatics. 2011 Jun 15;27(12):1739-40
references: 21546393
references: Lab Invest. 2005 May;85(5):702-15
references: 15765119
references: J Clin Invest. 2007 Jan;117(1):60-9
references: 17200707
references: Mol Microbiol. 2001 Nov;42(3):729-40
references: 11722738
references: Clin Cancer Res. 2008 Apr 1;14(7):2227-35
references: 18381965
references: Proc Natl Acad Sci U S A. 2006 Aug 22;103(34):12741-6
references: 16912112
references: J Endod. 2004 Apr;30(4):209-12
references: 15085047
references: J Gastroenterol Hepatol. 2005 Aug;20(8):1266-78
references: 16048577
references: J Infect Dis. 1996 Mar;173(3):743-6
references: 8627044
references: Gut. 2001 Jun;48(6):743-7
references: 11358884
references: J Gastroenterol Hepatol. 2008 Aug;23(8 Pt 1):1298-303
references: 18624900
references: Gastroenterology. 2008 Jan;134(1):306-23
references: 18166359
references: Gastroenterology. 2002 Aug;123(2):542-53
references: 12145807
references: Physiol Rev. 2007 Jan;87(1):245-313
references: 17237347
references: Helicobacter. 2005 Jun;10(3):179-84
references: 15904475
references: J Med Microbiol. 2009 Apr;58(Pt 4):509-516
references: 19273648
references: BMC Bioinformatics. 2009 May 27;10:161
references: 19473525
references: Nat Rev Cancer. 2002 Apr;2(4):301-10
references: 12001991
references: Oncogene. 2005 Mar 31;24(14):2354-66
references: 15735748
references: PLoS One. 2008 Jul 30;3(7):e2836
references: 18665274
references: Nat Rev Gastroenterol Hepatol. 2010 Nov;7(11):629-41
references: 20938460
references: Gastroenterology. 2002 Jan;122(1):119-33
references: 11781287
references: Infect Immun. 2012 Oct;80(10):3545-58
references: 22851748
references: Int J Mol Sci. 2011 Jan 13;12(1):334-52
references: 21339989
references: Free Radic Biol Med. 2009 Nov 1;47(9):1239-53
references: 19628035
references: Gut. 1994 Feb;35(2):179-85
references: 8307467
references: Aliment Pharmacol Ther. 2005 May 1;21(9):1121-6
references: 15854174
references: Genome Biol. 2004;5(10):R80
references: 15461798
references: Eur J Cancer. 2001 Aug;37(12):1482-7
references: 11506954
references: Proc Natl Acad Sci U S A. 2005 Oct 25;102(43):15545-50
references: 16199517
references: Nature. 2008 Jul 24;454(7203):436-44
references: 18650914
references: Gastroenterology. 2005 Sep;129(3):1005-18
references: 16143138
references: Antioxid Redox Signal. 2010 Jan;12(1):125-69
references: 19624272
references: Clin Cancer Res. 2009 May 1;15(9):2995-3002
references: 19383819
references: Mol Cell Biol. 2001 Apr;21(7):2475-84
references: 11259596
references: Nature. 2002 Dec 19-26;420(6917):860-7
references: 12490959
references: Int J Cancer. 2007 Dec 1;121(11):2373-80
references: 17893866
references: Gastroenterology. 1998 Jun;114(6):1169-79
references: 9609753
references: Cancer Sci. 2008 May;99(5):836-42
references: 18294278
references: Nature. 2006 May 25;441(7092):431-6
references: 16724054
references: Front Biosci. 2004 Sep 01;9:2335-46
references: 15353291
references: Front Biosci (Landmark Ed). 2009 Jan 01;14:4015-34
references: 19273331
references: Microbiology (Reading). 2009 Jun;155(Pt 6):1749-1757
references: 19383684
references: Antioxid Redox Signal. 2006 Sep-Oct;8(9-10):1573-82
references: 16987012
references: J Exp Med. 2011 Mar 14;208(3):519-33
references: 21282379
references: Gastroenterology. 2004 Nov;127(5):1446-62
references: 15521014
references: World J Surg. 2000 Mar;24(3):315-20
references: 10658066
references: J Radiat Res. 2008 Jul;49(4):329-40
references: 18596371
references: World J Gastroenterol. 2007 Nov 14;13(42):5547-51
references: 17948927
references: Gut. 2012 Oct;61(10):1398-409
references: 22180059
references: J Biol Chem. 2008 Jun 20;283(25):16961-5
references: 18420576
references: Carcinogenesis. 2002 Mar;23(3):529-36
references: 11895869
references: Cancer Res. 2008 Dec 1;68(23):9909-17
references: 19047172
references: Am J Physiol Lung Cell Mol Physiol. 2000 Dec;279(6):L1005-28
references: 11076791