Role of Escherichia coli infection in colorectal cancer

Role of Escherichia coli infection in colorectal cancer
Fatemeh Maghool,^1,* Aida Haidari,² Samane Mohammadzadeh,³
2. Department of Cell and Molecular Biology and Microbiology, Faculty of Biological Sciences and Technologies, University of Isfahan, Isfahan, Iran
Introduction: Colorectal cancer (CRC) is one of most common cancer diagnosed worldwide annually. It is a heterogeneous disease and numerous factors such as environmental, genetic, epigenetic, infection, inflammation as well as intestinal microorganisms are involved in CRC onset and progression. Gut bacteria have a critical role in the biological microenvironment and prolonged bacterial infection is associated with colonic tumourigenesis. Mucosa-associated microbiota such as Escherichia coli are mostly identified in colonic tissue of CRC patients. This review summarized the possible pathways involved in colorectal carcinogenesis of E. coli.
Methods: The MEDLINE, Embase, and Cochrane database were searched from 2010 to 2020 and English relevant articles were selected for review.
Results: Tumor-infiltrating Macrophages, contribute to the main steps of carcinogenesis through secreting multiple factors including COX-2/PGE2. The protumoral function of COX-2/PGE2 is influenced by tumor microenvironment. Colon cancer-associated E. coli promote intestinal inflammation and protumoral activities of macrophages by inducing persistent cyclooxygenase-2 (COX-2) expression. Indeed, the association of E. coli with pro-inflammatory infiltrates may increase tumor growth. Mucosally adherent E. coli may also contribute to the colorectal neoplasia progression by downregulating mismatch repair proteins such as MSH2 and MLH1, that are involved in DNA damage associated apoptotic signaling and protecting cells from mutations. Furthermore, cancer-associated E. coli able to produce colibactin, a genotoxin with oncogenic potential.
Conclusion: E. coli may play critical role in colorectal cancer progression via different mechanisms. Additional studies will determine the precise role of E. coli in colorectal tumourigenesis which may be used therapeutically.
Keywords: Escherichia coli, Colorectal, Cancer, Gut, Microbiota