Gut Microbiota and Cancer: From Pathogenesis to Therapy

Abstract

Cancer is a multifactorial pathology and it represents the second leading cause of death worldwide. In the recent years, numerous studies highlighted the dual role of the gut microbiota in preserving host’s health. Gut resident bacteria are able to produce a number of metabolites and bioproducts necessary to protect host’s and gut’s homeostasis. Conversely, several microbiota subpopulations may expand during pathological dysbiosis and therefore produce high levels of toxins capable, in turn, to trigger both inflammation and tumorigenesis. Importantly, gut microbiota can interact with the host either modulating directly the gut epithelium or the immune system. Numerous gut populating bacteria, called probiotics, have been identified as protective against the genesis of tumors. Given their capability of preserving gut homeostasis, probiotics are currently tested to help to fight dysbiosis in cancer patients subjected to chemotherapy and radiotherapy. Most recently, three independent studies show that specific gut resident species may potentiate the positive outcome of anti-cancer immunotherapy. The highly significant studies, uncovering the tight association between gut microbiota and tumorigenesis, as well as gut microbiota and anti-cancer therapy, are here described. The role of the Lactobacillus rhamnosus GG (LGG), as the most studied probiotic model in cancer, is also reported. Overall, according to the findings here summarized, novel strategies integrating probiotics, such as LGG, with conventional anti-cancer therapies are strongly encouraged.

Cell-mediated immune resistance in cancer

“…The commensal gut microbiota plays an important role in stimulating the host immune system, for example, by producing multiprotein complexes called inflammasomes [181] . Researchers are characterizing the patient gut microbiome to link the composition to tumorigenic potential as well as to patient response to anti-PD-1 immunotherapy [3,181,182] . Data generated from high-throughput techniques have made bioinformatics and computational sciences a necessity in translational cancer research [183] .…”

High-fat Diet Induced Dysbiosis & Amelioration by Astaxanthin

“…Normally there is equilibrium between the gut microbiota and host, as well as between bacterial species. When this balance is disrupted, dysbiosis 11 and opportunistic infections occur, greatly influencing aging 12 , nutrition 13 , the efficacy of medication 14,15 , physiological function 16 , immune function 17 , and carcinogenesis [18][19][20] of the host. In this review we introduce the results of two studies of astaxanthin.…”

A Tool for the Treatment of Gastrointestinal Tumors: Micro- Ecological Immunotherapy

“…The intestinal microbes have rapidly become a focus of extensive research in a variety of fields. The gut microbiota is considered to be the hidden immune organ of the human body, regulating the function and homeostasis of many organs throughout the body [44]. Nutritional support plays a crucial role in the immune and postoperative recovery of cancer patients.…”