Campylobacter jejuni promotes colorectal tumorigenesis through the action of cytolethal distending toxin

Abstract

Objective Campylobacter jejuni produces a genotoxin, cytolethal distending toxin (CDT), which has DNAse activity and causes DNA double-strand breaks. Although C. jejuni infection has been shown to promote intestinal inflammation, the impact of this bacterium on carcinogenesis has never been examined.DesignGerm-free (GF) ApcMin/+ mice, fed with 1% dextran sulfate sodium, were used to test tumorigenesis potential of CDT-producing C. jejuni. Cells and enteroids were exposed to bacterial lysates to determine DNA damage capacity via γH2AX immunofluorescence, comet assay and cell cycle assay. To examine the interplay of CDT-producing C. jejuni, gut microbiome and host in tumorigenesis, colonic RNA-sequencing and faecal 16S rDNA sequencing were performed. Rapamycin was administrated to investigate the prevention of CDT-producing C. jejuni-induced tumorigenesis.ResultsGF ApcMin/+ mice colonised with human clinical isolate C. jejuni81–176 developed significantly more and larger tumours when compared with uninfected mice. C. jejuni with a mutated cdtB subunit, mutcdtB, attenuated C. jejuni-induced tumorigenesis in vivo and decreased DNA damage response in cells and enteroids. C. jejuni infection induced expression of hundreds of colonic genes, with 22 genes dependent on the presence of cdtB. The C. jejuni-infected group had a significantly different microbial gene expression profile compared with the mutcdtB group as shown by metatranscriptomic data, and different microbial communities as measured by 16S rDNA sequencing. Finally, rapamycin could diminish the tumorigenic capability of C. jejuni.ConclusionHuman clinical isolate C. jejuni 81–176 promotes colorectal cancer and induces changes in microbial composition and transcriptomic responses, a process dependent on CDT production.

Toward Standards in Clinical Microbiota Studies: Comparison of Three DNA Extraction Methods and Two Bioinformatic Pipelines

“…The colorectal cancer microbiota present in biopsy specimens was indistinguishable from negative controls or fecal microbiota. As colorectal cancer development has been associated with specific gut bacteria, we were interested to see if colorectal cancer tissue itself also contained bacteria (37,38). DNA concentrations were sufficient for all samples to pass QC, but extracted DNA was likely mostly human derived.…”

Toward standards in clinical microbiome studies: comparison of three DNA extraction methods and two bioinformatic pipelines

“…As colorectal cancer development has been associated with specific gut bacteria, we were interested to see if colorectal cancer tissue itself also contained bacteria (45, 46). DNA concentrations were sufficient for all samples to pass QC, but extracted DNA was likely mostly human-derived.…”

Cytolethal Distending Toxin: from mitotic DNA damage to cGAS-dependent pro-inflammatory response

“…Persistent infection causes chronic inflammation, a driving force of tumor development [41]. CDT production during bacterial infection promotes inflammation and persistent colonization, and may eventually contribute to tumorigenesis [3][4][5][6][7]. In a broad range of cellular lineages, CDT intoxination induces DNA damage and a proinflammatory signature [8], but how these two events are linked has never been addressed so far.…”

“…E.col CDT (WT or the catalytic dead mutant H153A), H. duc CDT and C. jej CDT were produced and purified as previously described [7,10,19]. ATM inhibitor KU-55933 (ATMi) and ATR inhibitor VE-821 (ATRi) were purchased from Selleckchem and used at a final concentration of 10 mM.…”

“…CDT from C. jej or H. hep promote persistent gastrointestinal bacterial colonization, accompanied by chronic gastritis and/or typhlocolitis in mice models [3,4]. Besides, the production of CDT from the same bacteria is associated to carcinogenicity in susceptible mice backgrounds [5][6][7], raising the issue of putative links between CDT-mediated DNA damage, proinflammatory response from the host and tumorigenic processes [8].…”