Fecal Microbiota Differences According to the Risk of Advanced Colorectal Neoplasms

Long-term follow-up of colorectal cancer screening attendees identifies differences in Phascolarctobacterium spp. using 16S rRNA and metagenome sequencing

Background

The microbiome has been implicated in the initiation and progression of colorectal cancer (CRC) in cross-sectional studies. However, there is a lack of studies using prospectively collected samples.

Methods

From the Norwegian Colorectal Cancer Prevention (NORCCAP) trial, we analyzed 144 archived fecal samples from participants who were diagnosed with CRC or high-risk adenoma (HRA) at screening and from participants who remained cancer-free during 17 years of follow-up. We performed 16S rRNA sequencing of all the samples and metagenome sequencing on a subset of 47 samples. Differences in taxonomy and gene content between outcome groups were assessed for alpha and beta diversity and differential abundance.

Results

Diversity and composition analyses showed no significant differences between CRC, HRA, and healthy controls. Phascolarctobacterium succinatutens was more abundant in CRC compared with healthy controls in both the 16S and metagenome data. The abundance of Bifidobacterium and Lachnospiraceae spp. was associated with time to CRC diagnosis.

Conclusion

Using a longitudinal study design, we identified three taxa as being potentially associated with CRC. These should be the focus of further studies of microbial changes occurring prior to CRC diagnosis.

Inhibitory Effects of Bound Polyphenol from Foxtail Millet Bran on Colitis-Associated Carcinogenesis by the Restoration of Gut Microbiota in a Mice Model

Colorectal cancer (CRC) is a common malignant tumor occurring in the colon. It has been known that the gut microbiota is a complex ecosystem and plays an important role in the pathogenesis of colorectal cancer. Our previous study showed that bound polyphenol of the inner shell (BPIS) from foxtail millet bran exhibited significant antitumor activities in cancer cells and nude mice models. In the present study, the anticancer potential of BPIS is evaluated in the azoxymethane (AOM) and dextran sodium sulfate (DSS)-induced mouse CRC model. Results showed that BPIS could decrease the number and volume of tumors and protect the epithelial architecture from damage. Certain biomarkers associated with CRC formation, such as COX-2, EMR1, PCNA, and caspase-3, were strongly changed by BPIS. Moreover, by 16S rRNA gene sequence analysis, it was found that BPIS could remodel the overall structure of the gut microbiota from tumor-bearing mice toward that of the normal counterparts, including two phyla and eight genera, together with regulations on several genes that are responsible for 17 signaling pathways.

Microbiome in Colorectal Cancer: How to Get from Meta-omics to Mechanism?

Mounting evidence from metagenomic analyses suggests that a state of pathological microbial imbalance or dysbiosis is prevalent in the gut of patients with colorectal cancer. Several bacterial taxa have been identified of which representative isolate cultures interact with human cancer cells in vitro and trigger disease pathways in animal models. However, how the complex interrelationships in dysbiotic communities may be involved in cancer pathogenesis remains a crucial question. Here, we provide a survey of current knowledge of the gut microbiome in colorectal cancer. Moving beyond observational studies, we outline new experimental approaches for gaining ecosystem-level mechanistic understanding of the gut microbiome's role in cancer pathogenesis.

Moderate alteration to gut microbiota brought by colorectal adenoma resection

BACKGROUND AND AIM: Microbial dysbiosis is involved in the development of colorectal cancer and its most common precancerous lesion, colorectal adenoma. Endoscopic resection is one of the procedures for primary prevention of colorectal cancer, yet little is known about how the endoscopic therapy influences gut microbiota.

METHODS

We conducted a prospective study of 20 patients who underwent endoscopic resection of colorectal adenoma and analyzed the fecal microbiota before and 3 months after adenoma resection. MiSeq sequencing of 16S rRNA genes was performed to determine the alterations in microbial diversity and structure. To discriminate the microbiota of the two groups, random forest and receiver operating characteristic analysis were applied, and a genus-based microbiota signature was obtained.

RESULTS

Despite few alterations in overall microbial structure after adenoma resection, the abundance of Parabacteroides revealed a significant increase postoperatively (3.8% vs 1.5%, 0.1160), and the microbiota signature of Parabacteroides, Streptococcus, and Ruminococcus showed an optimal discriminating performance of postoperative status with the area under the curve 0.788, P < 0.001.

CONCLUSION

Fecal microbial alterations indicate the moderate influence of adenoma resection on gut microbiota and lay the groundwork for microbial prediction of adenoma recurrence. Larger sample studies are further required to validate the findings.

Effect of the Chinese Medicine YangZheng XiaoJi on Reducing Fatigue in Mice with Orthotopic Transplantation of Colon Cancer

Background

Fatigue is a common, distressing, and persistent symptom for patients with malignant tumor including colorectal cancer (CRC). Although studies of cancer-related fatigue (CRF) have sprung out in recent years, the pathophysiological mechanisms that induce CRF remain unclear, and effective therapeutic interventions have yet to be established.

Methods

To investigate the effect of the traditional Chinese medicine YangZheng XiaoJi (YZXJ) on CRF, we constructed orthotopic colon cancer mice, randomly divided into YZXJ group and control (NS) group. Physical or mental fatigue was respectively assessed by swimming exhaustion time or suspension tail resting time. At the end of the experiment, serum was collected to measure the expression level of inflammatory factors by ELISA and feces to microbiota changes by 16s rDNA, and hepatic glycogen content was detected via the anthrone method.

Result

The nutritional status of the YZXJ group was better than that of the control group, and there was no statistical difference in tumor weight. The swimming exhaustion times of YZXJ group and control group were (162.80 ± 14.67) s and (117.60 ± 13.42, P < 0.05) s, respectively; the suspension tail resting time of YZXJ group was shorter than that of the control group (49.85 ± 4.56) s and (68.83 ± 7.26) s, P < 0.05)). Serum levels of IL-1β and IL-6 in YZXJ group were significantly lower than the control group (P < 0.05). Liver glycogen in YZXJ group was (5.18 ± 3.11) mg/g liver tissue, which was significantly higher than that in control group (2.95 ± 2.06) mg/g liver tissue (P < 0.05). At phylum level, increased abundance of Bacteroidetes, Verrucomicrobia, Actinobacteria, and Cyanobacteria and decreased Proteobacteria in YZXJ group emerged as the top differences between the two groups, and the Firmicutes/Bacteroidetes ratio was decreased in YZXJ group compared to the control group. At genus level, the abundance of Parabacteroides, unidentified Saprospiraceae, and Elizabethkingia which all belong to phylum Bacteroidetes were increased, while Arcobacter, Marinobacter, Alkanindiges, Sulfuricurvum, Haliangium, and Thiobacillus in phylum Proteobacteria were decreased after YZXJ intervention. YZXJ can also increase Pirellula, Microbacterium, and Alpinimonas and decrease Rubrobacter and Iamia.

Conclusion

YZXJ may reduce the physical and mental fatigue caused by colorectal cancer by inhibiting inflammatory reaction, promoting hepatic glycogen synthesis, and changing the composition of intestinal microbiota.