Cytotoxic necrotizing factor 1 hinders colon tumorigenesis induced by colibactin-producing Escherichia coli in Apc^Min/+ mice

ABSTRACT

Colorectal cancer (CRC) patients are frequently colonized by colibactin-producing Escherichia coli (CoPEC) (>40%), which enhances tumorigenesis in mouse models of CRC. We observed that 50% of CoPEC also contains the cnf1 gene, which encodes cytotoxic necrotizing factor-1 (CNF1), an enhancer of the eukaryotic cell cycle. The impact of its co-occurrence with colibactin (Clb) has not yet been investigated. We evaluated the impact of CNF1 on colorectal tumorigenesis using human colonic epithelial HT-29 cells and CRC-susceptible Apc^Min/+ mice inoculated with the CoPEC 21F8 clinical strain (Clb+Cnf+) or 21F8 isogenic mutants (Clb+Cnf-, Clb-Cnf+ and Clb-Cnf-). Infection with the Clb+Cnf- strain induced higher levels of inflammatory cytokines and senescence markers both in vitro and in vivo compared to those induced by infection with the Clb+Cnf+ strain. In contrast, the Clb+Cnf- and Clb+Cnf+ strains generated similar levels of DNA damage in HT-29 cells and in colonic murine tissues. Furthermore, the Apc^Min/+ mice inoculated with the Clb+Cnf- strain developed significantly more tumors than the mice inoculated with the Clb+Cnf+ strain or the isogenic mutants, and the composition of their microbiota was changed. Finally, rectal administration of the CNF1 protein in Apc^Min/+ mice inoculated with the Clb+Cnf- strain significantly decreased tumorigenesis and inflammation. Overall, this study provides evidence that CNF1 decreases the carcinogenic effects of CoPEC in Apc^Min/+ mice by decreasing CoPEC-induced cellular senescence and inflammation.

KEYWORDS:

• Colorectal cancer; Escherichia coli; colibactin; CNF-1; CoPEC

Acknowledgments

We thank Laurent Guillouard for providing technical assistance. We thank the CLIC (Clermont-Ferrand Imagerie Confocale, Université Clermont Auvergne) with help from Caroline Vachias and Anipath histology technical platforms (GReD, Université Clermont Auvergne) for assistance with tissue preparation and immunohistochemical staining. We also thank Christelle Blavignac from the CICS for cell cycle analysis.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

The data that support the findings of this study are available in Mendeley data at http://doi.org/10.17632/zwck97zw4k.1.

Supplementary material

Supplemental data for this article can be accessed online at https://doi.org/10.1080/19490976.2023.2229569.

Additional information

Funding

This study was supported by the Ministère de la Recherche et de la Technologie; Inserm (UMR 1071); INRAe (USC-1382), Région Auvergne Rhône Alpes; the French government’s IDEX-ISITE initiative 16-IDEX-0001 (CAP 20-25 project of the University of Clermont Auvergne); and the National Program “Microbiote” Inserm. ”