Association of the microbiome with colorectal cancer development (Review)

Abstract

Colorectal cancer (CRC) is the second most common malignancy causing cancer-related mortality globally. It is the third most common type of cancer detected worldwide. The recent concept of the human body supporting a diverse community of microbes has revealed the important role these microbes play synergistically in maintaining normal homeostasis. The balance between the microbiomes and epithelial cells of the human body is essential for normal physiology. Evidence from meta-genome analysis indicates that an imbalance in the microbiome is prominent in the guts of patients with CRC. Several studies have suggested that the gut microbiota can secrete metabolites [short-chain fatty acids (SCFAs), vitamins, polyphenols and polyamines] that modulate the susceptibility of the colon and rectum by altering inflammation and DNA damage. The state of microbiome imbalance (dysbiosis) has been reported in patients with CRC, with an increasing population of 'bad' microbes and a decrease in 'good' microbes. The 'good' microbes, also known as commensal microbes, produce butyrate; however, 'bad' microbes cause a pro-inflammatory state. The complex association between pathological microbial communities leading to cancer progression is not yet fully understood. An altered microbial metabolite profile plays a direct role in CRC metabolism. Furthermore, diet plays an essential role in the risk of gastrointestinal cancer development. High-fiber diets regulate the gut microbiome and reduce the risk of CRC development, and may be fruitful in the better management of therapeutics. In the present review, the current status of the microbiome in CRC development is discussed. Contents 1. Introduction 2. Bacteria associated with CRC 3. Bacterial metabolites and CRC development 4. Host-microbe interaction 5. Microbiome-associated early diagnosis 6. Exploiting the microbiome for CRC therapeutics 7. Conclusion

Inhibition of the Occurrence and Development of Inflammation-Related Colorectal Cancer by Fucoidan Extracted from Sargassum fusiforme

“…At the tumor-initiation stage, inflammatory cells can produce ROS and reactive nitrogen intermediates, which significantly increase the probability of mutation in neighboring epithelial cells, thereby promoting tumor formation. After the formation of tumors, key transcription factors such as NF-κB and STAT3 can be activated in precancerous cells, which further accelerate the proliferation, growth, and metastasis of cancer cells . The positive effects of fucoidan in relieving intestinal inflammation and improving the intestinal microecology have been reported. , The noncytotoxic effect of fucoidan on FHC has been confirmed in our study (Figure A).…”

“…Once this balance is upset, an increase in the number of “bad” microbes may exacerbate intestinal inflammation. The presence of an inflammatory environment in the gut may further disrupt the composition of intestinal microflora of mice and promote the progression of inflammation-associated CRC . The presence of an inflammatory environment in the gut may disrupt the gut microbiome in mice.…”

Recent Advances in Understanding the Structure and Function of the Human Microbiome

“…Others are implicated in causing GIT inflammation that might progress into chronic conditions. Several review articles discussed the role of the microbiome in GIT inflammation and immune response (Abdulla et al, 2021;Sanders et al, 2021). Beyond GIT, inflammation is linked to intrauterine growth restriction (IUGR) in humans (Al-Azemi et al, 2017).…”

An evolutionary explanation for antibiotics’ association with increased colon cancer risk

“…Studies have reported a gut microbiome imbalance (dysbiosis) in patients with colorectal cancer, showing an increase of the population of ‘bad’ microbes compared to a decrease of ‘good’ microbes [ 47 ]. In light of these studies, the association of antibiotics with colon cancer has been attributed to microbiome imbalance.…”