A comprehensive analysis of the microbiota composition and host driver gene mutations in colorectal cancer

Abstract

Studies of both, microbiota and target therapy associated with gene mutations in colorectal cancer, (CRC) have attracted increasing attention. However, only a few of them analyzed the combined effects on CRC. we analyzed differences in intestinal microbiota of 44 colorectal cancer patients and 20 healthy controls (HC) using 16S rRNA gene sequencing of fecal samples. For 39 of the CRC patients, targeted Next Generation Sequencing (NGS) was carried out at formalin fixed paraffin embedded (FFPE) samples to identify somatic mutation profiles. Compared to the HC group, the microbial diversity of CRC patients was significantly lower. In the CRC group, we found a microbiome that was significantly enriched for strains of Bifidobacterium, Bacteroides, and Megasphaera whereas in the HC group the abundance of Collinsella, Faecalibacterium, and Agathobacter strains was higher. Among the mutations detected in the CRC group, the APC gene had the highest mutation rate (77%, 30/39). We found that the KRAS mutant type was closely associated with Faecalibacterium, Roseburia, Megamonas, Lachnoclostridium, and Harryflintia. Notably, Spearman correlation analysis showed that KRAS mutations were negatively correlated with the existence of Bifidobacterium and positively correlated with Faecalibacterium. By employing 16S rRNA gene sequencing, we identified more unique features of microbiota profiles in CRC patients. For the first time, our study showed that gene mutations could directly be linked to the microbiota composition of CRC patients. We hypothesize that the effect of a targeted colorectal cancer therapy is also closely related to the colorectal flora, however, this requires further investigation.