Implication of gut microbes and its metabolites in colorectal cancer

Abstract

Background: Colorectal cancer (CRC) is the third most common cancer with a significant impact on loss of life. In 2020, nearly 1.9 million new cases and over 9,35,000 deaths were reported. Numerous microbes that are abundant in the human gut benefit host physiology in many ways. Although the underlying mechanism is still unknown, their association appears to be crucial in the beginning and progression of CRC. Diet has a significant impact on the microbial composition and may increase the chance of getting CRC. Increasing evidence points to the gut microbiota as the primary initiator of colonic inflammation, which is connected to the development of colonic tumors. However, it is unclear how the microbiota contributes to the development of CRCs. Patients with CRC have been found to have dysbiosis of the gut microbiota, which can be identified by a decline in commensal bacterial species, such as those that produce butyrate, and a concurrent increase in harmful bacterial populations, such as opportunistic pathogens that produce pro-inflammatory cytokines. We believe that using probiotics or altering the gut microbiota will likely be effective tools in the fight against CRC treatment.

Purpose: In this review, we revisited the association between gut microbiota and colorectal cancer whether cause or effect. The various factors which influence gut microbiome in patients with CRC and possible mechanism in relation with development of CRC.

Conclusion: The clinical significance of the intestinal microbiota may aid in the prevention and management of CRC.

Keywords: Biomarker; Colorectal cancer; MPE; Microbiota; ROS/RNS; Short chain fatty acids.

Fig. 1

Representation of dietary, lifestyle and host’s genetic factors affects the gut microbiome that leads to dysbiosis of gut bacteria, consequently leading to the development of colorectal cancers via producing oncometabolite, inflammation, oxidative stress, genotoxins, virulence factors and biofilm

Fig. 2

Representation of Dysbiosis of the gut microbiota increases the permeability of the gut mucosa, allowing bacteria to move more easily and producing more free and non-free radical ROS/RNS species that can cause DNA damage and genetic mutation. As a result, persistent inflammation brought on by oncogene activation and tumor-suppressor gene inactivation finally results in CRC. ROS reactive oxygen species, RNS reactive nitrogen species, NADIS nonsteroidal anti-inflammatory drug, ETC electron transport chain