Gut mucosal microbiota profiles linked to colorectal cancer recurrence

Abstract

Background: Emerging evidence links gut microbiota to various human diseases including colorectal cancer (CRC) initiation and development. However, gut microbiota profiles associated with CRC recurrence and patient prognosis are not completely understood yet, especially in a Chinese cohort.

Aim: To investigate the relationship between gut mucosal microbiota profiles and CRC recurrence and patient prognosis.

Methods: We obtained the composition and structure of gut microbiota collected from 75 patients diagnosed with CRC and 26 healthy controls. The patients were followed up by regular examination to determine whether tumors recurred. Triplet-paired samples from on-tumor, adjacent-tumor and off-tumor sites of patients diagnosed with/without CRC recurrence were analyzed to assess spatial-specific patterns of gut mucosal microbiota by 16S ribosomal RNA sequencing. Next, we carried out bioinformatic analyses, Kaplan-Meier survival analyses and Cox regression analyses to determine the relationship between gut mucosal microbiota profiles and CRC recurrence and patient prognosis.

Results: We observed spatial-specific patterns of gut mucosal microbiota profiles linked to CRC recurrence and patient prognosis. A total of 17 bacterial genera/families were identified as potential biomarkers for CRC recurrence and patient prognosis, including Anaerotruncus, Bacteroidales, Coriobacteriaceae, Dialister, Eubacterium, Fusobacterium, Filifactor, Gemella, Haemophilus, Mogibacteriazeae, Pyramidobacter, Parvimonas, Porphyromonadaceae, Slackia, Schwartzia, TG5 and Treponema.

Conclusion: Our work suggests that intestinal microbiota can serve as biomarkers to predict the risk of CRC recurrence and patient death.

Keywords: 16S rRNA sequencing analysis; Biomarker; Colorectal cancer; Colorectal cancer recurrence; Gut microbiota; Prognosis.

Figure 1

Microbial alpha-diversities showing significant differences at adjacent-tumor site. A: Alpha diversity evaluated using Chao1 index; B: Alpha diversity evaluated using Fisher index; C: Alpha diversity evaluated using observed operational taxonomic unit index; D: Alpha diversity evaluated using Shannon index; E: Alpha diversity evaluated using Simpson index. health: Healthy control; nn: Off-tumor site of patient without colorectal cancer (CRC) recurrence; nr: Off-tumor site of patient with CRC recurrence; pn: Adjacent-tumor site of patient without CRC recurrence; pr: Adjacent-tumor site of patient with CRC recurrence; tn: On-tumor site of patient without CRC recurrence; tr: On-tumor site of patient with CRC recurrence. Alpha-diversity differences were compared using student’s t-test.

Figure 2

Principal component analysis showed spatial- and recurrence-specific patterns of microbiota profiles. health: Healthy control; nn: Off-tumor site of patient without colorectal cancer (CRC) recurrence; nr: Off-tumor site of patient with CRC recurrence; pn: Adjacent-tumor site of patient without CRC recurrence; pr: Adjacent-tumor site of patient with CRC recurrence; tn: On-tumor site of patient without CRC recurrence; tr: On-tumor site of patient with CRC recurrence.

Figure 3

Patterns of bacterial taxonomy at the phylum level collected from spatial-specific sites of patients with or without colorectal cancer recurrence. health: Healthy control; nn: Off-tumor site of patient without colorectal cancer (CRC) recurrence; nr: Off-tumor site of patient with CRC recurrence; pn: Adjacent-tumor site of patient without CRC recurrence; pr: Adjacent-tumor site of patient with CRC recurrence; tn: On-tumor site of patient without CRC recurrence; tr: On-tumor site of patient with CRC recurrence.

Figure 4

Linear discriminant analysis effect size analysis showed the genera or families with unknown genus with significant differential abundances at off-tumor, adjacent-tumor or on-tumor sites of patients with and without colorectal cancer recurrence. The colors in the heatmap represent the abundance of genera/families with unknown genus. Red: High abundance; Blue: low abundance. health: Healthy control; nn: Off-tumor site of patient without colorectal cancer (CRC) recurrence; nr: Off-tumor site of patient with CRC recurrence; pn: Adjacent-tumor site of patient without CRC recurrence; pr: Adjacent-tumor site of patient with CRC recurrence; tn: On-tumor site of patient without CRC recurrence; tr: On-tumor site of patient with CRC recurrence; LDA: The linear discriminant analysis.

Figure 5

The relationship between bacterial abundance and overall survival. A: Kaplan-Meier curves of bacteria at on-tumor site and overall survival (OS); B: Kaplan-Meier curves of bacteria at adjacent-tumor site and OS. ^aP < 0.05; ^bP < 0.01; ^cP < 0.001; ^dP < 0.0001. X-axis: OS (mo), Y-axis: Survival probability.

Figure 6

The relationship between bacterial abundance and disease-free survival. A: Kaplan-Meier curves of bacteria at on-tumor site and disease-free survival (DFS); B: Kaplan-Meier curves of bacteria at adjacent-tumor site and DFS. ^aP < 0.05; ^bP < 0.01; ^cP < 0.001; ^dP < 0.0001.