Metagenomics analysis reveals universal signatures of the intestinal microbiota in colorectal cancer, regardless of regional differences

Abstract

The human gut microbiota is a complex and dynamic community of microorganisms living in our intestines and has emerged as an important factor for colorectal adenocarcinoma (CRC). The purpose of our study was to investigate the microbiota composition in Brazilian CRC patients compared with a local control population (CTL) to find out which changes could be considered universal or regional features in CRC microbiota. Fecal samples were obtained from 28 CRC and 23 CTL individuals. The 16S rRNA gene was used for metagenomic analysis. In addition to the anthropometric variables, the clinical stage (TNM 2018) was considered. Patients with CRC had a significant increase in alpha diversity and a higher percentage of genus Prevotella and a decreased proportion of Megamonas and Ruminococcus . Additionally, the proportion of Faecalibacterium prausnitzii was associated with a better prognosis in the first stages of CRC, and Fusobacterium nucleatum proved to be an important marker of colorectal carcinogenesis and tumor aggressiveness. Although regional differences influence the composition of the microbiota, in the case of CRC, the microhabitat created by the tumor seems to be a major factor. Our results contribute to a better understanding of the carcinogenic process, and even in different environments, some factors appear to be characteristic of the microbiota of patients with CRC.

Meta-analyses of host metagenomes from colorectal cancer patients reveal strong relationship between colorectal cancer-associated species

“…Although Bacteroides fragilis has been previously associated to CRC, 20,95,96 the presence of other species of the genus have been previously reported. 97 Our network show three small clusters of Bacteroides: Bacteroides uniformis and Bacteroides ovatus clusters are both present in both conditions, supporting reports of the genus being common in the human gut, but Bacteroides zhangwenhongi present only in CRC. We could hypothesise that, with the genus being associated to the immune response, the abundance of these species in CRC patients could be related to an immune response of the host, but further studies are required.…”

Intestinal Microbiota and miRNA in IBD: A Narrative Review about Discoveries and Perspectives for the Future

“…The phylum Verrucomicrobia includes only one representative species, namely Akkermansia muciniphila , which is abundant in the gastrointestinal tract, and has attracted considerable interest in studies involving microbiota and IBD [ 38 , 39 , 40 ]. In the Fusobacteria phylum, a gram-negative anaerobic bacillus ( Fusobacterium nucleatum ) has a symbiotic relationship with its host but could also cause opportunistic infections and has recently garnered attention in several studies on the role of the microbiome in colorectal cancer [ 41 , 42 ]. The phylum Actinobacteria includes Collinsella and Bifidobacterium , while the common phylum Proteobacteria includes Escherichia and Desulfovibrio genera.…”

Diet-mediated gut microbial community modulation and signature metabolites as potential biomarkers for early diagnosis, prognosis, prevention and stage-specific treatment of colorectal cancer

“…Faecal and metagenomic studies by different scientists [92] , [93] indicated that some gut bacterial species are predominant in the faecal samples as well as tumor microenvironments of patients with CRC, in high abundance, compared to those of healthy individuals and normal tissues adjacent to tumor microenvironments. This provides insights into the possible correlation between these bacterial species and colorectal carcinogenesis.…”