The microbiota of the large intestine plays an important role in host metabolism and
maintenance of host health
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shared by Nathan Goodyear on 15 Feb 14
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The Effect of Oral Feeding of Tribulus t... [Int J Fertil Steril. 2013] - PubMed - NCBI - 0 views
www.ncbi.nlm.nih.gov/...24520465
Tribulus Tribulus terrestris low T Testosterone opiates opiate addiction
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Martinick Hair Restoration Clinic Offers World Class Facilities & Techniques - 0 views
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Feedgy - Willow Medical - Medical Equipment - 0 views
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shared by Nathan Goodyear on 06 May 15
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BMC Microbiology | Full text | The Firmicutes / Bacteroidetes ratio of the human microb... - 0 views
www.biomedcentral.com/...123
gut flora gut microbiome gut microbiota firmicutes bacteroidetes firmicutes_bacteroidetes health gut microbiome
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Our results defining a standard adult profile, together with previous reports, showed that C. leptum, C. coccoides, Bacteroides and Bifidobacterium represent the four dominant groups of the adult fecal microbiota
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Sub-dominant groups are Lactobacilli Enterobacteriaceae, Desulfovibrio, Sporomusa, Atopobium as well as other bacterial groups including Clostridium clusters XI, XIVb, and XVIII
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Strict anaerobes, such as Clostridium, colonize at later stages, as can be seen by the relatively low levels of C. leptum and C. coccoides in infants
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diet change must be considered among the primary causes for such a shift of microbiota between infants and adults.
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In the case of elderly subjects, our qPCR results indicated a significant increase in the counts of E. coli when compared to adults. This data is consistent with other publications indicating that elderly subjects harbor a different E. coli microbiota profile compared to younger adults
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a number of authors reported a reduction in the numbers and diversity of many protective commensal anaerobes, such as Bacteroides and Bifidobacteria
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The Firmicutes to Bacteroidetes ratio was already shown to be of significant relevance in signaling human gut microbiota status
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Our measurements of the Firmicutes/Bacteroidetes ratio in adults obtained by our species-specific qPCR are in agreement with those obtained by Ley et al
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Compared with young adults, the elderly have a different digestive physiology, characterized at a physiological level by a reduction in transit and of digestive secretions
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The Firmicutes/Bacteroidetes ratio undergoes an increase from birth to adulthood and is further altered with advanced age
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Effect of the long-term feeding of dietary lipids on the learning ability, fatty acid c... - 0 views
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Time-Restricted Feeding Is a Preventative and Therapeutic Intervention against Diverse ... - 0 views
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Impaired clearance, not overproduction of toxic proteins, may underlie Alzheimer's dise... - 0 views
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Effects of maternal docosahexaenoic acid intake on visual function and neurodevelopment... - 0 views
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Mechanisms of Leptin Action and Leptin Resistance - Annual Review of Physiology, 70(1):537 - 0 views
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The failure of elevated leptin levels to suppress feeding and mediate weight loss in common forms of obesity defines a state of so-called leptin resistance.
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shared by Nathan Goodyear on 21 Oct 11
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High Fructose Feeding Induces Copper Deficiency in... [J Hepatol. 2011] - PubMed - NCBI - 0 views
www.ncbi.nlm.nih.gov/...21781943
fructose diet dietary Copper cu deficiency non-alcoholic fatty liver disease NAFLD
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shared by Nathan Goodyear on 04 Aug 14
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Metabolic endotoxemia: a molecular link between obesity and cardiovascular risk - 0 views
jme.endocrinology-journals.org/...R51.full
metabolic endotoxemia obesity insulin resistance cardiovascular disease LPS inflammation
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The starting point for innate immunity activation is the recognition of conserved structures of bacteria, viruses, and fungal components through pattern-recognition receptors
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TLRs are transmembrane proteins containing extracellular domains rich in leucine repeat sequences and a cytosolic domain homologous to the IL1 receptor intracellular domain
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The major proinflammatory mediators produced by the TLR4 activation in response to endotoxin (LPS) are TNFα, IL1β and IL6, which are also elevated in obese and insulin-resistant patients
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Obesity, high-fat diet, diabetes, and NAFLD are associated with higher gut permeability leading to metabolic endotoxemia.
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LPS promotes hepatic insulin resistance, hypertriglyceridemia, hepatic triglyceride accumulation, and secretion of pro-inflammatory cytokines promoting the progression of fatty liver disease.
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In the endothelium, LPS induces the expression of pro-inflammatory, chemotactic, and adhesion molecules, which promotes atherosclerosis development and progression.
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In the adipose tissue, LPS induces adipogenesis, insulin resistance, macrophage infiltration, oxidative stress, and release of pro-inflammatory cytokines and chemokines.
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the gut microbiota has been recently proposed to be an environmental factor involved in the control of body weight and energy homeostasis by modulating plasma LPS levels
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dietary fats alone might not be sufficient to cause overweight and obesity, suggesting that a bacterially related factor might be responsible for high-fat diet-induced obesity.
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This was accompanied in high-fat-fed mice by a change in gut microbiota composition, with reduction in Bifidobacterium and Eubacterium spp.
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n humans, it was also shown that meals with high-fat and high-carbohydrate content (fast-food style western diet) were able to decrease bifidobacteria levels and increase intestinal permeability and LPS concentrations
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it was demonstrated that, more than the fat amount, its composition was a critical modulator of ME (Laugerette et al. 2012). Very recently, Mani et al. (2013) demonstrated that LPS concentration was increased by a meal rich in saturated fatty acids (SFA), while decreased after a meal rich in n-3 polyunsaturated fatty acids (n-3 PUFA).
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this effect seems to be due to the fact that some SFA (e.g., lauric and mystiric acids) are part of the lipid-A component of LPS and also to n-3 PUFA's role on reducing LPS potency when substituting SFA in lipid-A
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these experimental results suggest a pivotal role of CD14-mediated TLR4 activation in the development of LPS-mediated nutritional changes.
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This suggests a link between gut microbiota, western diet, and obesity and indicates that gut microbiota manipulation can beneficially affect the host's weight and adiposity.
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endotoxemia was independently associated with energy intake but not fat intake in a multivariate analysis
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in vitro that endotoxemia activates pro-inflammatory cytokine/chemokine production via NFκB and MAPK signaling in preadipocytes and decreased peroxisome proliferator-activated receptor γ activity and insulin responsiveness in adipocytes.
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LPS-induced release of glucagon, GH and cortisol, which inhibit glucose uptake, both peripheral and hepatic
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Recent evidence has been linking ME with dyslipidemia, increased intrahepatic triglycerides, development, and progression of alcoholic and nonalcoholic fatty liver disease
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The hepatocytes, rather than hepatic macrophages, are the cells responsible for its clearance, being ultimately excreted in bile
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All the subclasses of plasma lipoproteins can bind and neutralize the toxic effects of LPS, both in vitro (Eichbaum et al. 1991) and in vivo (Harris et al. 1990), and this phenomenon seems to be dependent on the number of phospholipids in the lipoprotein surface (Levels et al. 2001). LDL seems to be involved in LPS clearance, but this antiatherogenic effect is outweighed by its proatherogenic features
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LPS produces hypertriglyceridemia by several mechanisms, depending on LPS concentration. In animal models, low-dose LPS increases hepatic lipoprotein (such as VLDL) synthesis, whereas high-dose LPS decreases lipoprotein catabolism
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When a dose of LPS similar to that observed in ME was infused in humans, a 2.5-fold increase in endothelial lipase was observed, with consequent reduction in total and HDL. This mechanism may explain low HDL levels in ‘ME’ and other inflammatory conditions such as obesity and metabolic syndrome
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It is known that the high-fat diet and the ‘ME’ increase intrahepatic triglyceride accumulation, thus synergistically contributing to the development and progression of alcoholic and NAFLD, from the initial stages characterized by intrahepatic triglyceride accumulation up to chronic inflammation (nonalcoholic steatohepatitis), fibrosis, and cirrhosis
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On the other hand, LPS activates Kupffer cells leading to an increased production of ROS and pro-inflammatory cytokines like TNFα
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high-fat diet mice presented with ME, which positively and significantly correlated with plasminogen activator inhibitor (PAI-1), IL1, TNFα, STAMP2, NADPHox, MCP-1, and F4/80 (a specific marker of mature macrophages) mRNAs
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prebiotic administration reduces intestinal permeability to LPS in obese mice and is associated with decreased systemic inflammation when compared with controls
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Cani et al. also found that high-fat diet mice presented with not only ME but also higher levels of inflammatory markers, oxidative stress, and macrophage infiltration markers
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This suggests that important links between gut microbiota, ME, inflammation, and oxidative stress are implicated in a high-fat diet situation
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high-fat feeding is associated with adipose tissue macrophage infiltration (F4/80-positive cells) and increased levels of chemokine MCP-1, suggesting a strong link between ME, proinflammatory status, oxidative stress, and, lately, increased CV risk
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markers of systemic inflammation such as circulating bacterial endotoxin were elevated in patients with chronic infections and were strong predictors of increased atherosclerotic risk
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As a TLR4 ligand, LPS has been suggested to induce atherosclerosis development and progression, via a TLR4-mediated inflammatory state.
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shared by Nathan Goodyear on 12 Nov 14
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Cancer cells metabolically "fertilize" the tumor microenvironment with hydrogen peroxid... - 0 views
www.ncbi.nlm.nih.gov/...PMC3180189
cancer reverse warburg effect warburg effect NF-kapppB HIF-1alpha Cav-1 H2O2
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reducing oxidative stress with powerful antioxidants, is an important strategy for cancer prevention, as it would suppress one of the key early initiating steps where DNA damage and tumor-stroma metabolic-coupling begins. This would prevent cancer cells from acting as metabolic “parasites
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Oxidative stress in cancer-associated fibroblasts triggers autophagy and mitophagy, resulting in compartmentalized cellular catabolism, loss of mitochondrial function, and the onset of aerobic glycolysis, in the tumor stroma. As such, cancer-associated fibroblasts produce high-energy nutrients (such as lactate and ketones) that fuel mitochondrial biogenesis and oxidative metabolism in cancer cells. We have termed this new energy-transfer mechanism the “reverse Warburg effect.
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Then, oxidative stress, in cancer-associated fibroblasts, triggers the activation of two main transcription factors, NFκB and HIF-1α, leading to the onset of inflammation, autophagy, mitophagy and aerobic glycolysis in the tumor microenvironment
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oxidative stress and ROS, produced in cancer-associated fibroblasts, has a “bystander effect” on adjacent cancer cells, leading to DNA damage, genomic instability and aneuploidy, which appears to be driving tumor-stroma co-evolution
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tumor cells produce and secrete hydrogen peroxide, thereby “fertilizing” the tumor microenvironment and driving the “reverse Warburg effect.”
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This type of stromal metabolism then produces high-energy nutrients (lactate, ketones and glutamine), as well as recycled chemical building blocks (nucleotides, amino acids, fatty acids), to literally “feed” cancer cells
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loss of stromal caveolin (Cav-1) is sufficient to drive mitochondrial dysfunction with increased glucose uptake in fibroblasts, mimicking the glycolytic phenotype of cancer-associated fibroblasts.
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Then, cancer-associated fibroblasts show quantitative reductions in mitochondrial activity and compensatory increases in glucose uptake, as well as high ROS production
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These findings may explain the prognostic value of a loss of stromal Cav-1 as a marker of a “lethal” tumor microenvironment
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aerobic glycolysis takes place in cancer-associated fibroblasts, rather than in tumor cells, as previously suspected.
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our results may also explain the “field effect” in cancer biology,5 as hydrogen peroxide secreted by cancer cells, and the propagation of ROS production, from cancer cells to fibroblasts, would create an increasing “mutagenic field” of ROS production, due to the resulting DNA damage
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Interruption of this process, by addition of catalase (an enzyme that detoxifies hydrogen peroxide) to the tissue culture media, blocks ROS activity in cancer cells and leads to apoptotic cell death in cancer cells
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In this new paradigm, cancer cells induce oxidative stress in neighboring cancer-associated fibroblasts
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cancer cells secrete hydrogen peroxide, which induces ROS production in cancer-associated fibroblasts
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Then, oxidative stress in cancer-associated fibroblast leads to decreases in functional mitochondrial activity, and a corresponding increase in glucose uptake, to fuel aerobic glycolysis
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fibroblasts and cancer cells in co-culture become metabolically coupled, resulting in the development of a “symbiotic” or “parasitic” relationship.
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cancer-associated fibroblasts undergo aerobic glycolysis (producing lactate), while cancer cells use oxidative mitochondrial metabolism.
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We have previously shown that oxidative stress in cancer-associated fibroblasts drives a loss of stromal Cav-1, due to its destruction via autophagy/lysosomal degradation
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a loss of stromal Cav-1 is sufficient to induce further oxidative stress, DNA damage and autophagy, essentially mimicking pseudo-hypoxia and driving mitochondrial dysfunction
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loss of stromal Cav-1 is a powerful biomarker for identifying breast cancer patients with early tumor recurrence, lymph-node metastasis, drug-resistance and poor clinical outcome
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this type of metabolism (aerobic glycolysis and autophagy in the tumor stroma) is characteristic of a lethal tumor micro-environment, as it fuels anabolic growth in cancer cells, via the production of high-energy nutrients (such as lactate, ketones and glutamine) and other chemical building blocks
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one such enzymatically-active protein anti-oxidant that may be of therapeutic use is catalase, as it detoxifies hydrogen peroxide to water
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numerous studies show that “catalase therapy” in pre-clinical animal models is indeed sufficient to almost completely block tumor recurrence and metastasis
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by eliminating oxidative stress in cancer cells and the tumor microenvironment,55 we may be able to effectively cut off the tumor's fuel supply, by blocking stromal autophagy and aerobic glycolysis
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breast cancer patients show systemic evidence of increased oxidative stress and a decreased anti-oxidant defense, which increases with aging and tumor progression.68–70 Chemotherapy and radiation therapy then promote further oxidative stress.69 Unfortunately, “sub-lethal” doses of oxidative stress during cancer therapy may contribute to tumor recurrence and metastasis, via the activation of myofibroblasts.
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a loss of stromal Cav-1 is associated with the increased expression of gene profiles associated with normal aging, oxidative stress, DNA damage, HIF1/hypoxia, NFκB/inflammation, glycolysis and mitochondrial dysfunction
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cancer-associated fibroblasts show the largest increases in glucose uptake, while cancer cells show corresponding decreases in glucose uptake, under identical co-culture conditions
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Thus, increased PET glucose avidity may actually be a surrogate marker for a loss of stromal Cav-1 in human tumors, allowing the rapid detection of a lethal tumor microenvironment.
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In the brain, astrocytes are glycolytic and undergo aerobic glycolysis. Thus, astrocytes take up and metabolically process glucose to lactate.7
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Then, lactate is secreted via a mono-carboxylate transporter, namely MCT4. As a consequence, neurons use lactate as their preferred energy substrate
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both astrocytes and cancer-associated fibroblasts express MCT4 (which extrudes lactate) and MCT4 is upregulated by oxidative stress in stromal fibroblasts.34
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In accordance with the idea that cancer-associated fibroblasts take up the bulk of glucose, PET glucose avidity is also now routinely used to measure the extent of fibrosis in a number of human diseases, including interstitial pulmonary fibrosis, postsurgical scars, keloids, arthritis and a variety of collagen-vascular diseases.
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PET glucose avidity and elevated serum inflammatory markers both correlate with poor prognosis in breast cancers.
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PET signal over-estimates the actual anatomical size of the tumor, consistent with the idea that PET glucose avidity is really measuring fibrosis and inflammation in the tumor microenvironment.
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human breast and lung cancer patients can be positively identified by examining their exhaled breath for the presence of hydrogen peroxide.
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tumor cell production of hydrogen peroxide drives NFκB-activation in adjacent normal cells in culture6 and during metastasis,103 directly implicating the use of antioxidants, NFκB-inhibitors and anti-inflammatory agents, in the treatment of aggressive human cancers.
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How is the Immune System Suppressed by Cancer - 1 views
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Excellent work by Prof de Groot of Essen, indicated by adding exogenous xanthine oxidase ( XO) in hepatoma cells, hydrogen peroxide was produced to destroy the hepatoma cells
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The other important influence of NO is in its inhibition of the proapoptoic caspases cascade. This in turn protects the cells from intracellular preprogrammed death.
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nitric oxide in immune suppression in relation to oxygen radicals is its inhibitory effect on the binding of leukocytes (PMN) at the endothelial surface
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NO from the tumor cells actually suppresses the iNOS, and in addition it reduces oxygen radicals to stop the formation of peroxynitrite in these cells. But NO is not the only inhibitor of iNOS in cancer.
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Prostaglandin E2, released from tumor cells is also an inhibitor of iNOS, as well as suppressing the immune system
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Th-1 subset of T-cells. These cells are responsible for anti-viral and anti-cancer activities, via their cytokine production including Interleukin-2, (IL-2), and Interleukin-12 which stimulates T-killer cell replication and further activation and release of tumor fighting cytokines.
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Th1 cells stimulate NK and other tumor fighting macrophages via IL-2 and IL-12; In contrast, Th2, which is stimulated in allergies and parasitic infections, produce IL-4 and IL-10. IL-4 and IL-10 inhibit TH-1 activation and the histamine released from mast cell degranulation upregulates T suppressor cells to further immune suppression.
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Th-2 subset of lymphocytes, on the other hand are activated in allergies and parasitic infections to release Interleukin-4 and Interleukin-10
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Mast cells contain histamine which when released increases the T suppressor cells, to lower the immune system and also acts directly on many tumor Histamine receptors to stimulate tumor growth
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Tumor cells release IL-10, and this is thought to be one of the important areas of Th-1 suppression in cancer patients
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IL-10 is also a central regulator of cyclooxygenase-2 expression and prostaglandin production in tumor cells stimulating their angiogenesis and NO production
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nitric oxide in tumor cells even prevents the activation of caspases responsible for apoptosis
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early stages of carcinogenesis, which we call tumor promotion, one needs a strong immune system, and fewer oxygen radicals to prevent mutations but still enough to destroy the tumor cells should they develop
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later stages of cancer development, the oxygen radicals are decreased around the tumors and in the tumor cells themselves, and the entire cancer fighting Th-1 cell replication and movement are suppressed. The results are a decrease in direct toxicity and apoptosis, which is prevented by NO, a suppression of the macrophage and leukocyte toxicity and finally, a suppression of the T-cell induced tumor toxicity
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elevated lactic acid which neutralizes the toxicity and activity of Lymphocyte immune response and mobility
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The lactic acid is also feeding fungi around tumors and that leads to elevated histamine which increases T-suppressor cells. Histamine alone stimulates many tumor cells.
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last but not least, the Lactic acid from tumor cells and acidic diets shifts the lymphocyte activity to reduce its efficacy against cancer cells and pathogens in addition to altering the bacteria of the intestinal tract.
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intestinal tract bacteria in cancer cells release sterols that suppress the immune system and down regulate anticancer activity from lymphocytes.
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In addition to the lactic acid, adenosine is also released from tumors. Through IL-10, adenosine and other molecules secreted by regulatory T cells, the CD8+ cells can be inactivated to an anergic state
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Adenosine is a purine nucleoside found within the interstitial fluid of solid tumors at concentrations that are able to inhibit cell-mediated immune responses to tumor cells
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Adenosine appears to up-regulate the PD1 receptor in T-1 Lymphocytes and inhibits the immune system further
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Mast cells with their release of histamine lower the immune system and also stimulate tumor growth and activate the metalloproteinases involved in angiogenesis and metastases
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Cimetidine, an antihistamine has been actually shown to increase in apoptosis in MDSC via a separate mechanism than the antihistamine effect
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In vitro analyses revealed a striking induction of IL-8 expression in CAFs and LFs by tumor necrosis factor-alpha (TNF-alpha)
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these data raise the possibility that the majority of CAFs in CLM originate from resident LFs. TNF-alpha-induced up-regulation of IL-8 via nuclear factor-kappaB in CAFs is an inflammatory pathway, potentially permissive for cancer invasion that may represent a novel therapeutic target
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Gastroenteric tube feeding: Techniques, problems and solutions - 0 views
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shared by Nathan Goodyear on 04 Oct 17
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Chronic exposure to Low dose bacterial lipopolysaccharide inhibits leptin signaling in ... - 0 views
www.ncbi.nlm.nih.gov/...PMC4523075
LPS lipopolysaccharides leptin CCK cholecystokinin metabolism weight appetite diet nutrition inflammation
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Obesity and models of obesity induced by ingestion of HF-diet in rodents are associated with chronically elevated circulating levels of LPS
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chronic low-dose administration of LPS induces leptin-resistance in vagal afferent neurons and abolition of CCK-induced inhibition of food intake
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HF fat feeding has been shown to enhance gastrointestinal permeability promoting the translocation of LPS to the circulation
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LPS leads to an increase in SOCS3 expression [20]. SOCS3 is a negative regulator of leptin signaling
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the data provides a mechanism linking changes in gut microbiota induced by ingestion of HF diets to dysregulation of food intake and body weight
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SOCS3 is an important mechanism by which leptin resistance develops in vagal afferent neurons and coincides with the onset of hyperphagia
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Chronic low-dose LPS treatment induced TLR4 activation and MyD88 signaling in vagal afferent neurons, associated with increased SOCS3 expression and reduced leptin-signaling, characterized by the absence of leptin-induced pSTAT3.
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We demonstrate that this chronic low dose LPS is sufficient to induce leptin–resistance in vagal afferent neurons, reduced sensitivity to the satiating effects of CCK, and loss of vagal afferent plasticity
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it suggests that the increase in food intake and body weight we observed at week 6 in the LPS treated rats may be caused by LPS-induced leptin resistance.
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shared by Nathan Goodyear on 08 Dec 17
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Oncotarget | NADH autofluorescence, a new metabolic biomarker for cancer stem cells: Id... - 0 views
www.oncotarget.com/index.php
vitamin C IV vitamin C cancer cancer stem cells milk thistle silymarin ascorbic acid bee propolis CAPE glycolytic inhibitor natural
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Cancer stem-like cells (CSCs) are thought to be the root cause of chemotherapy-resistance and radio-resistance
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ultimately leading to treatment failure in patients with advanced disease [1-3]. They have been directly implicated mechanistically in tumor recurrence and metastasis, resulting in poor patient survival
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Our results indicate that increased mitochondrial oxidative stress and high NADH levels are both key characteristics of the CSC metabolic phenotype
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high levels of NAD(P)H auto-fluorescence are known to be a surrogate marker for mitochondrial “power”, high OXPHOS capacity and increased ATP production
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an intact NAD+ salvage pathway is strictly required for mammosphere formation, supporting our results using NAD(P)H auto-fluorescence, which enriched CSC activity by more than 5-fold.
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Since glycolysis is especially critical for maintaining the TCA cycle, OXPHOS and overall mitochondrial function, we next assessed the effects of known glycolytic inhibitors
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we show that two other natural products that function as effective glycolysis inhibitors, also inhibited mammosphere formation. More specifically, vitamin C (ascorbic acid), which induces oxidative stress and inhibits the activity of GAPDH (a key glycolytic enzyme) [17], also inhibited mammosphere formation, with an IC-50 of 1 mM (Figure 7B). Therefore, vitamin C was ~10 times more potent than 2-DG at targeting CSC propagation
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silibinin (the major active constituent of silymarin, an extract of milk thistle seeds) [18], which specifically functions as an inhibitor of glucose uptake, blocked mammosphere formation, with an IC-50 between 200 and 400 µM
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caffeic acid phenyl ester (CAPE), a key component of honey-bee propolis, has potent anti-cancer properties
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Because of it aromatic ring structure (Figure 8), we speculated that CAPE might function as a potent inhibitor of oxidative mitochondrial metabolism
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CAPE quantitatively inhibits the mitochondrial oxygen consumption rate (OCR) and, in turn, induces the onset of aerobic glycolysis (ECAR)
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CAPE shows a clear selectivity for targeting CSCs and adherent cancer cells, relative to normal fibroblasts.
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CAPE functions as a “natural” mitochondrial OXPHOS inhibitor, that preferentially targets the CSC sub-population. This could explain CAPE’s known anti-cancer properties
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Our data directly shows that a small fraction of the total cell population, characterized by increased PGC1α activity, high mitochondrial ROS/H2O2 and high NADH levels, has the ability to survive and grow under anchorage-independent conditions, driving mammosphere formation
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We highlight the utility of certain natural products, such as Silibinin, Vitamin C and CAPE, that could be used to therapeutically target CSCs. Silibinin is the major active component of silymarin, which is an extract prepared from milk thistle seeds.
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Previous studies have also shown that when non-CSCs and CSCs are both fed mitochondrial fuels (such as L-lactate or ketone bodies), that CSCs quantitatively produce more NADH in response to this stimulus
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The Noble Prize winner, Linus Pauling, was among the first to describe and clinically test the efficacy of Vitamin C, as a relatively non-toxic anti-cancer agent
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Vitamin C has two mechanisms of action. First, it is a potent pro-oxidant, that actively depletes the reduced glutathione pool, leading to cellular oxidative stress and apoptosis in cancer cells. Moreover, it also behaves as an inhibitor of glycolysis, by targeting the activity of GAPDH, a key glycolytic enzyme.
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Here, we show that Vitamin C can also be used to target the CSC population, as it is an inhibitor of energy metabolism that feeds into the mitochondrial TCA cycle and OXPHOS
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Vitamin C may prove to be promising agent for new clinical trials, aimed at testing its ability to reduce CSC activity in cancer patients, as an add-on to more conventional therapies, to prevent tumor recurrence, further disease progression and metastasis
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Interestingly, a breast cancer based clinical study has already shown that the use of Vitamin C, concurrent with or within 6 months of chemotherapy, significantly reduces both tumor recurrence and patient mortality
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CAPE quantitatively reduces mitochondrial oxygen consumption (OCR), while inducing a reactive increase in glycolysis (ECAR). As such, it potently inhibits mammosphere formation with an IC-50 of ~2.5 µM. Similarly, it also significantly inhibits cell migration
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we also demonstrate that 7 different inhibitors of key energetic pathways can be used to effectively block CSC propagation, including three natural products (silibinin, ascorbic acid and CAPE). Future studies will be necessary to test their potential for clinical benefit in cancer patients.
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The future of cancer therapy is cancer stem cells. Study finds that Vitamin C, silymarin, and bee propolis blocks mitochondrial energy pathways in cancer stem cells. Vitamin C is a known glycolytic inhbitor. Vitamin C was found to inhibit glycolysis via GAPDH targeting to inhibit the energy pathways of the mitochondria in CSCs. The authors propse that Vitamin C can be used as add on therapies for conventional therapies to specifically attack the CSCs and their contribution to recrurence, treatment resistance, and metastasis potential all in addition to the ability of vitamin C to reduce the side effects of chemotherapy.
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shared by Nathan Goodyear on 09 Feb 21
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Induction of metastasis, cancer stem cell phenotype, and oncogenic metabolism in cancer... - 0 views
www.ncbi.nlm.nih.gov/...PMC5282724
EMT TME metastasis cancer stem cells cancer MMP2 Notch MMP-9 MMP-2 radioresistance Hedgehog CSC MMP9 Snail HIF-1alpha tumor microenvironment epithelial to mesenchymal transition TGF-beta radiation
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Nuclear DNA is the primary target of IR; it causes DNA damage (genotoxic stress) by direct DNA ionization
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EMT, stemness, and oncogenic metabolism are known to be associated with resistance to radiotherapy and chemotherapy
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Hanahan and Weinberg proposed ten hallmarks of cancer that alter cell physiology to enhance malignant growth: 1) sustained proliferation, 2) evasion of growth suppression, 3) cell death resistance, 4) replicative immortality, 5) evasion of immune destruction, 6) tumour-promoting inflammation, 7) activation of invasion and metastasis, 8) induction of angiogenesis, 9) genome instability, and 10) alteration of metabolism
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EMT is a developmental process that plays critical roles in embryogenesis, wound healing, and organ fibrosis
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transforming growth factor-β [TGF-β], epidermal growth factor [EGF]) and their associated signalling proteins (Wnt, Notch, Hedgehog, nuclear-factor kappa B [NF-κB], extracellular signal-regulated kinase [ERK], and phosphatidylinositol 3-kinase [PI3K]/Akt
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activate EMT-inducing transcription factors, including Snail/Slug, ZEB1/δEF1, ZEB2/SIP1, Twist1/2, and E12/E47
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IR has been shown to induce EMT to enhance the motility and invasiveness of several cancer cells, including those of breast, lung, and liver cancer, and glioma cells
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IR may increase metastasis in both the primary tumour site and in normal tissues under some circumstance
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sublethal doses of IR have been shown to enhance the migratory and invasive behaviours of glioma cells
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High levels of ROS trigger cell death by causing irreversible damage to cellular components such as proteins, nucleic acids, and lipids, whereas low levels of ROS have been shown to promote tumour progression—including tumour growth, invasion, and metastasis
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Treatment with the N-acetylcysteine (NAC), a general ROS scavenger, prevents IR-induced EMT, adhesive affinity, and invasion of breast cancer cells
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IR activates the p38 MAPK pathway, which contributes to the induction of Snail expression to promote EMT and invasion
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HIF-1 is a heterodimer composed of an oxygen-sensitive α subunit and a constitutively expressed β subunit.
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Under normoxia, HIF-1α is rapidly degraded, whereas hypoxia induces stabilisation and accumulation of HIF-1α
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levels of HIF-1α mRNA are enhanced by activation of the PI3K/Akt/mammalian target of rapamycin (mTOR)
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IR is known to increase stabilisation and nuclear accumulation of HIF-1α, since hypoxia is a major condition for HIF-1 activation
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IR causes the reoxygenation of hypoxic cancer cells to increase ROS production, which leads to the stabilisation and nuclear accumulation of HIF-1
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IR increases glucose availability under reoxygenated conditions that promote HIF-1α translation by activating the Akt/mTOR pathway
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The stabilised HIF-1α then translocates to the nucleus, dimerizes with HIF-1β, and increases gene expression— including the expression of essential EMT regulators such as Snail—to induce EMT, migration, and invasion
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PAI-1 signalling is also implicated in IR-induced Akt activation that increases Snail levels to induce EMT
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EGFR activation is known to be associated with IR-induced EMT, cell migration, and invasion by activating two downstream pathways: PI3K/Akt and Raf/MEK/ERK
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IR has been shown to induce Akt activation through several signalling pathways (EGFR, C-X-C chemokine receptor type 4 [CXCR4]/C-X-C motif chemokine 12 [CXCL12], plasminogen activator inhibitor 1 [PAI-1]) and upstream regulators (Bmi1, PTEN) that promote EMT and invasion
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CSCs possess a capacity for self-renewal, and they can persistently proliferate to initiate tumours upon serial transplantation, thus enabling them to maintain the whole tumour
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Conventional cancer treatments kill most cancer cells, but CSCs survive due to their resistance to therapy, eventually leading to tumour relapse and metastasis
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identification of CSCs, three types of markers are utilised: cell surface molecules, transcription factors, and signalling pathway molecules
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CSCs express distinct and specific surface markers; commonly used ones are CD24, CD34, CD38, CD44, CD90, CD133, and ALDH
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signalling pathways, including those of TGF-β, Wnt, Hedgehog, Notch, platelet-derived growth factor receptor (PDGFR), and JAK/STAT
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EMT-inducing transcription factors, such as Snail, ZEB1, and Twist1, are known to confer CSC properties
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Signalling pathways involved in EMT, including those of TGF-β, Wnt, and Notch, have been shown to play important roles in inducing the CSC phenotype
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TGF-β1 not only increases EMT markers (Slug, Twist1, β-catenin, N-cadherin), but also upregulates CSC markers (Oct4, Sox2, Nanog, Klf4) in breast and lung cancer cells
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IR has been shown to induce the CSC phenotype in many cancers, including breast, lung, and prostate cancers, as well as melanoma
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Genotoxic stress due to IR or chemotherapy promotes a CSC-like phenotype by increasing ROS production
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In prostate cancer patients, radiotherapy increases the CD44+ cell population that exhibit CSC properties
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IR also induces the re-expression of stem cell regulators, such as Sox2, Oct4, Nanog, and Klf4, to promote stemness in cancer cells
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EMT-inducing transcription factors and signalling pathways, including Snail, STAT3, Notch signalling, the PI3K/Akt pathway, and the MAPK cascade, have been shown to play important roles in IR-induced CSC properties
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STAT3 directly binds to the Snail promoter and increases Snail transcription, which induces the EMT and CSC phenotypes, in cisplatin-selected resistant cells
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Other oncogenic metabolic pathways, including glutamine metabolism, the pentose phosphate pathway (PPP), and synthesis of fatty acids and cholesterol, are also enhanced in many cancers
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cancer cells depend on mitochondrial metabolism and increase mitochondrial production of ROS that cause pseudo-hypoxia
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CAFs have defective mitochondria that lead to the cells exhibiting the Warburg effect; the cells take up glucose, and then secrete lactate to 'feed' adjacent cancer cells
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Epithelial cancer cells express MCT1, while CAFs express MCT4. MCT4-positive, hypoxic CAFs secrete lactate by aerobic glycolysis, and MCT1-expressing epithelial cancer cells then uptake and use that lactate as a substrate for the tricarboxylic acid (TCA) cycle
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MCT4-positive cancer cells depend on glycolysis and then efflux lactate, while MCT1-positive cells uptake lactate and rely on OXPHOS
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metabolic heterogeneity induces a lactate shuttle between hypoxic/glycolytic cells and oxidative/aerobic tumour cells
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bulk tumour cells exhibit a glycolytic phenotype, with increased conversion of glucose to lactate (and enhanced lactate efflux through MCT4), CSC subsets depend on oxidative phosphorylation; most of the glucose entering the cells is converted to pyruvate to fuel the TCA cycle and the electron transport chain (ETC), thereby increasing mitochondrial ROS production
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the major fraction of glucose is directed into the pentose phosphate pathway, to produce redox power through the generation of NADPH and ROS scavengers
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regulatory molecules involved in EMT and CSCs, including Snail, Dlx-2, HIF-1, STAT3, TGF-β, Wnt, and Akt, are implicated in the metabolic reprogramming of cancer cells
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HIF-1 induces the expression of glycolytic enzymes, including the glucose transporter GLUT, hexokinase, lactate dehydrogenase (LDH), and MCT, resulting in the glycolytic switch
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HIF-1 represses the expression of pyruvate dehydrogenase kinase (PDK), which inhibits pyruvate dehydrogenase (PDH), thereby inhibiting mitochondrial activity
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pyruvate kinase M2 (PKM2), LDH, and pyruvate carboxylase (PC), are implicated in the induction of the EMT and CSC phenotypes
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IR enhances glycolysis by upregulating GAPDH (a glycolysis enzyme), and it increases lactate production by activating LDHA, which converts pyruvate to lactate
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IR enhances glycolysis by upregulating GAPDH (a glycolysis enzyme), and it increases lactate production by activating LDHA, which converts pyruvate to lactate
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IR also elevates MCT1 expression that exports lactate into the extracellular environment, leading to acidification of the tumour microenvironment
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IR increases intracellular glucose, glucose 6-phosphate, fructose, and products of pyruvate (lactate and alanine), suggesting a role for IR in the upregulation of cytosolic aerobic glycolysis
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lactate stimulates cell migration and enhances secretion of hyaluronan from CAF that promote tumour metastasis
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promote tumour survival, growth, invasion, and metastasis; enhance the stiffness of the ECM; contribute to angiogenesis; and induce inflammation by releasing several growth factors and cytokines (TGF-β, VEGF, hepatocyte growth factor [HGF], PDGF, and stromal cell-derived factor 1 [SDF1]), as well as MMP
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tumours recruit the host tissue’s blood vessel network to perform four mechanisms: angiogenesis (formation of new vessels), vasculogenesis (de novo formation of blood vessels from endothelial precursor cells), co-option, and modification of existing vessels within tissues.
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immunosuppressive cells such as tumour-associated macrophages (TAM), MDSCs, and regulatory T cells, and the immunosuppressive cytokines, TGF-β and interleukin-10 (IL-10)
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immunosuppressive cells such as tumour-associated macrophages (TAM), MDSCs, and regulatory T cells, and the immunosuppressive cytokines, TGF-β and interleukin-10 (IL-10)
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The third phase, tumour escape, is mediated by antigen loss, immunosuppressive cells (TAM, MDSCs, and regulatory T cells), and immunosuppressive cytokines (TGF-β and IL-10).
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IR can elicit various changes in the TME, such as CAF activity-mediated ECM remodelling and fibrosis, cycling hypoxia, and an inflammatory response
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IR activates CAFs to promote the release of growth factors and ECM modulators, including TGF-β and MMP
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TGF-β directly influences tumour cells and CAFs, promotes tumour immune escape, and activates HIF-1 signalling
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MMPs degrade ECM that facilitates angiogenesis, tumour cell invasion, and metastasis
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IR promotes ROS production in cancer cells, which may induce the activation of oncogenes and the inactivation of tumour suppressors, which further promote oncogenic metabolism
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Although IR activates an antitumour immune response, this signalling is frequently suppressed by tumour escape mechanisms