Microbiome profile of colorectal cancer patients' gut mucosa and blood plasma samples

Abstract

Objective: Colorectal cancer (CRC) is one of the most common cancer types worldwide and the second leading cause of cancer-related mortality. The gut microbiome takes an important part in cancerogenesis. Moreover, bacterial sequences are found in the human bloodstream and might be of clinical significance. Thereby, the aim of this study was to identify microbiome profile of CRC patients using gut mucosa biopsy and blood plasma samples and find presumable biomarkers for CRC diagnostic. Material and Methods: In total, 313 people, including CRC patients, adenomatous polyps (AP) patients, and control individuals were recruited in this study. Blood and gut mucosa biopsies samples were collected and from all samples were extracted DNA. V1-V2 region of bacterial 16S rRNA gene were amplified and sequenced. Bioinformatical and statistical analysis were performed to reveal bacterial profile of each study group. Results: The global structures were significantly different between control, CRC, and AP groups both in biopsy and blood samples. Analysis revealed list of bacteria the number of which was significantly different between the groups. Tissues’ microbiome was 20 times richer than blood microbiome. In CRC patients’ samples bacterial richness and diversity decreased in tissue and increased in blood samples. Model of 8 bacterial DNA signatures in blood showed high sensitivity and specificity (AUC: 0.801). Conclusions: Based on tissue and blood microbial profile it was possible to distinguish heathy state from CRC or AP. Distinct bacterial DNA signatures in blood could presumably be used as biomarkers for CRC.