Gut microbiome of Moroccan colorectal cancer patients

Abstract

Although colorectal cancer is the third leading cause of death in Morocco, there are no studies of the microbiome changes associated with the disease in the Moroccan population. The aim of our study was to compare the stool microbiome of Moroccan cancer patients with healthy individuals. We analyzed the microbiome composition of samples from 11 CRC patients and 12 healthy individuals by 16S rRNA amplicon sequencing. Principal coordinate analysis of samples revealed defined cancer versus healthy clusters. Our findings showed that cancer samples had higher proportions of Firmicutes (T = 50.5%; N = 28.4%; p = 0.04), specifically of Clostridia (T = 48.3%; N = 19.0%; p = 0.002), and Fusobacteria (T = 0.1%; N = 0.0%; p = 0.02), especially of Fusobacteriia (T = 0.1%; N = 0.0%; p = 0.02), while Bacteroidetes were enriched in healthy samples (T = 35.1%; N = 62.8%; p = 0.06), particularly the class Bacteroidia (T = 35.1%; N = 62.6%; p = 0.06). Porphyromonas, Clostridium, Ruminococcus, Selenomonas, and Fusobacterium were significantly overrepresented in diseased patients, similarly to other studies. Predicted functional information showed that bacterial motility proteins, flagellar assembly, and fatty acid biosynthesis metabolism were significantly overrepresented in cancer patients, while amino acid metabolism and glycan biosynthesis were overrepresented in controls. This suggests that involvement of these functional metagenomes is similar and relevant in the carcinogenesis process, independent of the origin of the samples. Results from this study allowed identification of bacterial taxa relevant to the Moroccan population and encourages larger studies to facilitate population-directed therapeutic approaches.Electronic supplementary materialThe online version of this article (10.1007/s00430-018-0542-5) contains supplementary material, which is available to authorized users.

Foes or Friends? Bacteria Enriched in the Tumor Microenvironment of Colorectal Cancer

“…The abundance of Porphyromonas in the intestines of CRC patients is higher than that of healthy individuals. Further, Porphyromonas is more abundant in CRC tissues compared to adjacent non-cancer tissues (Table 2) [32,33,35,42,45,47]. However, how Porphyromonas is enriched in this tumor microenvironment remains unclear.…”

“…Among them, some have been recognized as opportunistic pathogens involved not only in periodontitis, inflammatory bowel disease, pancreatic abscess, premature, and hepatic abscess but also in CRC and oral cancer [73][74][75]. Many studies show that Fusobacterium is more abundant in the intestines of CRC patients compared to the healthy individuals [32,33,36,38,42,45,46]. Comparation between CRC tissues and adjacent non-cancer tissues also reveals that Fusobacterium is more abundant in the CRC tissues (Table 2) [30,36,37,43,44].…”

“…Many studies show that A. muciniphila has a higher relative abundance in CRC patients compared to healthy individuals (Table 2) [32,34,37]. For example, Byrd and Bresalier found that the expression of mucin 1 (MUC1) is increased in colon cancers and that of mucins 5AC (MUC5AC) is frequently present in colorectal adenomas and colon cancers [52] (Table 4), indicating that the enrichment of A. muciniphila in tumor microenvironment may result from the increased substrate concentration (Figure 2b).…”

“…They produce spores and are highly resistant to the outside environment. It mainly resides in the human intestine, and some studies indicate that the abundance of Clostridium in the intestines of CRC patients is higher than that of healthy individuals [31,32,46]. Further, Clostridium population is significant enhanced in the CRC tissues compared to the adjacent non-cancer tissues (Table 2) [44].…”

“…Peptostreptococcus is a Gram-positive, obligate anaerobic, nonmotile and spherical-or oval-shaped bacterium (Table 3), which is found in human oral cavity, upper respiratory tract, intestine, and female reproductive tract. Peptostreptococcus is considered to be a carcinogenic bacterium that promotes the development of CRC, and many studies have found that the abundance of Peptostreptococcus in the intestines of CRC patients is higher than that of healthy individuals [32,33,35,36,42,46]. In CRC patients, Peptostreptococcus also exhibits higher abundance in CRC tissues compared to adjacent non-cancer tissues (Table 2) [30,44].…”