Identifying Colibactin-Producing Escherichia coli as Candidate Biomarker for Aggressive Colorectal Cancer

Document Type : New and original researches in the field of Microbiology.

Authors

1 Department of Microbiology, College of Medicine, University of Thi-Qar, Thi-Qar, 6400

2 Department of Microbiology, College of Medicine, University of Thi-Qar, Thi-Qar, 6400; Cancer Research Unit, College of Medicine, University of Thi-Qar, Thi-Qar, 6400

3 Department of Histopathology and Forensic Medicine, College of Medicine, University of Thi-Qar, Thi- Qar, 64001

Abstract

Background: Colorectal cancer represents the third most common cause of carcinogenesis and aggressive cancer cases have been linked to some pathogenic microorganisms, including colibactin-producing Escherichia coli. There are few biomarkers for colorectal cancer diagnosis and prognosis. However, there have been documented clinical challenges in differentiating between aggressive cancers and those that are not. Objectives: This study was designed to investigate the genetic diversity of E. coli strains of both colorectal carcinoma-associated and non-associated E. coli strains. Methodology: Pathogenic E. coli isolates from benign (24) and malignant (80) colorectal tissue biopsies were characterized based on bacteriological analysis. The Pks (polyketide synthase) Island, which specifically targets of E coli genes such as clbB and uidA was examined using polymerase chain reaction. Results: The colibactin gene (clbB) was found to be increased significantly in the malignant (62%) compared to benign (0%) colorectal tissues ( p<0.001). The presence of this gene was also associated significantly with high grade (p=0.042) and tumor size (p=< 0.001) of colorectal carcinoma. In contrast, there was no significant association between uidA gene and colorectal carcinoma clinical parameters. Conclusion: The aggressiveness and development of colorectal cancer may be related to the clbB gene. Further research is required to determine the role of this gene in colorectal carcinoma and it could be used as a biomarker to identify colorectal cancer.

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