Chronic inflammation evoked by pathogenic stimulus during carcinogenesis

2019

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The microbiome, the relationship between environmental factors, a high-fat diet, morbid obesity, and host response have been associated with cancer, only a small fraction of which (<10%) are genetically triggered. This nongenetic association is underpinned by a worldwide increase in morbid obesity, which is associated with both insulin resistance and chronic inflammation. The connection of the microbiome and morbid obesity is reinforced by an approximate shift of about 47% in the estimated total number of bacteria and an increase from 38,000,000,000,000 in a reference man to 56,000,000,000,000 in morbid obesity leading to a disruption of the microbial ecology within the gut. Humans contain 6,000,000,000 microbes and more than 90% of the cells of the human body are microorganisms. Changes in the microflora of the gut are associated with the polarization of ion channels by butyrate, thereby influencing cell growth. The decrease in the relative proportion of Bacteroidetes together with a change in the fermentation of carbohydrates by bacteria is observed in morbid obesity. The disruption of homeostasis of the microflora in the obese changes signaling and crosstalk of several pathways, resulting in inflammation while suppressing apoptosis. The interactions between the microbiome and morbid obesity are important to understand signaling and crosstalk in the context of the progression of the six-step sequence of carcinogenesis. This disruption of homeostasis increases remodeling of the extracellular matrix and fibrosis followed by the none-resolvable precancerous niche as the internal pathogenic stimuli continue. The chronic stress explains why under such circumstances there is a greater proclivity for normal cells to undergo the transition to cancer cells.

Section: Discussionmentioning

confidence: 99%

Section: Microbiome (Tab 1)mentioning

confidence: 99%

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Microbiome and morbid obesity increase pathogenic stimulus diversity

2019

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“…Furthermore, important consequences of homeostasis disruption influencing the preparation of the precancerous niche (PCN) in this Special Issue "Disruption of signaling homeostasis induced crosstalk in the carcinogenesis paradigm Epistemology of the origin of cancer" include undervalued ubiquitous proteins [464], various pathogenic stimulus evoking chronic inflammation [465], remodeled fibrosis by chronic inflammation [466], the microbiome and morbi obesity [467] and PCN induced chronic cellmatrix stress with normal to cancer cell transition [468].…”

Section: Summary (Fig 4)mentioning

confidence: 99%

Eicosanoids in carcinogenesis

2019

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Inflammation is the body's reaction to pathogenic (biological or chemical) stimuli and covers a burgeoning list of compounds and pathways that act in concert to maintain the health of the organism. Eicosanoids and related fatty acid derivatives can be formed from arachidonic acid and other polyenoic fatty acids via the cyclooxygenase and lipoxygenase pathways generating a variety of pro- and anti-inflammatory mediators, such as prostaglandins, leukotrienes, lipoxins, resolvins and others. The cytochrome P450 pathway leads to the formation of hydroxy fatty acids, such as 20-hydroxyeicosatetraenoic acid, and epoxy eicosanoids. Free radical reactions induced by reactive oxygen and/or nitrogen free radical species lead to oxygenated lipids such as isoprostanes or isolevuglandins which also exhibit pro-inflammatory activities. Eicosanoids and their metabolites play fundamental endocrine, autocrine and paracrine roles in both physiological and pathological signaling in various diseases. These molecules induce various unsaturated fatty acid dependent signaling pathways that influence crosstalk, alter cell–cell interactions, and result in a wide spectrum of cellular dysfunctions including those of the tissue microenvironment. Although the complete role of eicosanoids, including that of the recently elucidated anti-inflammatory specialized pro-resolving lipid mediators (SPMs), e.g. lipoxins, resolvins, protectins and maresins, is not completely understood, the result of unremitting chronic inflammation is fostering early stages of carcinogenesis. Chronic inflammation facilitates the transition from a normal cell to a cancerous one. The disruption of homeostasis across a wide, but identifiable, swath of diverse molecular pathways creates a micromilieu which constitutes an early and necessary step in the 6-step sequence of carcinogenesis for the vast majority of cancers, termed “sporadic cancers”.

“…The significance of chronic inflammation in carcinogenesis has been reviewed [67]. In addition, an anti-inflammatory effect of Metformin was shown through the reduction of C-reactive protein (CRP), a marker of inflammation [68].…”

Section: Metformin and Inflammationmentioning

confidence: 99%

Metformin alters signaling induced crosstalk and homeostasis in the carcinogenesis paradigm “Epistemology of the origin of cancer”

2019

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The anti-hyperglycemic drug, Metformin, is effective in treating early stages of diabetes and has been associated with a 37% decrease in cancer incidence. While the precise mechanisms for the anti-cancer effects of Metformin remain to be elucidated, this review shows the multiplicity of its effects on interdicting signaling and crosstalk, anti-inflammatory effects and in restoring homeostasis, which, taken together, go beyond its well-known anti-hyperglycemic effect that serves as the basis for its use in type 2 diabetes. Metformin is much more than a one-trick pony. The recent discovery of several signaling pathways influenced by Metformin appears to have potential value in cancer therapy. Based on what we know at present, Metformin promotes beneficial effects attributed to its anti-inflammatory and anti-fibrotic effects largely demonstrated in vitro. Metformin activates or upregulates while it simultaneously inhibits or downregulates multiple signaling pathways of cell-cycle arrest and apoptosis accompanied by oxidative stress, which are in accordance with the 6-step sequence of carcinogenesis. Furthermore, in vivo studies in laboratory animals and in cancer patients are beginning to address the magnitude of the anti-cancer effects and delineate its anti-cancer effects. In this context, results from prior pancreatic and non-pancreatic cancer trials, which contained a significant proportion of the patient population treated with Metformin, will have to be reexamined in light of the observed anti-cancerous effects to gain additional insights. The detailed exploration of Metformin in the context of the “Disruption of signaling homeostasis induced crosstalk in the carcinogenesis paradigm Epistemology of the origin of cancer” can provide helpful insights into the anti-proliferative mechanisms and could play a relevant role in anti-cancer therapy in the future.