Microbiota Alterations in Gastrointestinal Cancers

Abstract

Commensal microbiota plays a critical role in the maintenance of human health. Microbes influence energy metabolism and nutrient absorption and help defend the host organism against pathogens. The composition of the gut microbiota is delicately balanced, and any alterations may lead to proinflammatory immune responses and initiation of disease processes, including cancer. Experimental evidence indicates that the human intestinal microbiota can influence tumour development and progression in the gastrointestinal tract by damaging DNA, activation of oncogenic signaling pathways, production of tumour-promoting metabolites, and suppression of the anti-tumour immune response. The aim of this article was to outline differences in human microbiota between healthy subjects and patients with gastrointestinal malignancies such as esophageal, stomach, liver, biliary tract, pancreas and colon inflammations, and cancers. A better understanding of microbiota changes in various gastrointestinal malignancies will enable a greater insight into the relationship between human microbiota composition and cancer development.

Newly Obtained Apple Pectin as an Adjunct to Irinotecan Therapy of Colorectal Cancer Reducing E. coli Adherence and β-Glucuronidase Activity

“…The disruption of gut microbiome equilibrium, called dysbiosis, often precedes the development of certain pathological conditions, from mild as irritable bowel syndrome to severe such as CRC. Colonic microbiota of CRC patients has been shown to differ from healthy individuals colonic flora [8,9]. Therefore, the impact of PC and SolC on the adherence of E. coli to colorectal cancer cells was studied.…”

“…Local inflammation may modulate the pathogenesis of CRC, mostly via the complex network of inflammation mediators, such as cytokines, produced both by cancer cells themselves and by various types of cells constituting tumor microenvironment [4]. Additionally, the progression of CRC can be influenced by colonic microbiota [5,6] that is altered in cancer patients as compared to the healthy subjects [7,8]. The microbiota was also shown to modulate the response of tumor cells to chemotherapy [9,10].…”

Antibiotic-Related Changes in Microbiome: The Hidden Villain behind Colorectal Carcinoma Immunotherapy Failure

“…Furthermore, lysates of Lactobacillus acidophilus also have enhanced anti-tumor efficacy of anti-CTLA-4 (cytotoxic T lymphocyte-associated protein 4) blocking antibody in mice CRC models, associated with increased CD8+ T cells, decreased numbers of T regulatory cells (Tregs), and decreased M2 macrophages in the tumor microenvironment [ 22 ]. Interestingly, bacterial genotoxins from Bacteroides fragilis , Campylobacter jejuni , and Fusobacterium nucleatum could promote CRC development in patients via activation of CD4+ Th17 cell responses, mTOR signaling, and the NF-kB pathway, respectively [ 23 , 24 ]. Additionally, bacteria such as ETBF and Fusobacterium nucleatum can impair the effectiveness of traditional chemotherapy and ICIs.…”