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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
shared by Nathan Goodyear on 09 Feb 21 - No Cached
  • More than half of cancer patients are treated with IR at some point during their treatment
  • fractionation schedule is the delivery of 1.8–2.0 Gy per day, five days per week
  • Nuclear DNA is the primary target of IR; it causes DNA damage (genotoxic stress) by direct DNA ionization
  • ...121 more annotations...
  • IR also indirectly induces DNA damage by stimulating reactive oxygen species (ROS) production
  • IR is known to induce EMT in vitro
  • p53 is activated in response to IR-induced DNA damage
  • IR paradoxically also promotes tumour recurrence and metastasis
  • DNA double-strand breaks (DSBs)
  • cancer cells undergoing EMT acquire invasive and metastatic properties
  • changes in the tumour microenvironment (TME)
  • IR seems to induce EMT and CSC phenotypes by regulating cellular metabolism
  • EMT, stemness, and oncogenic metabolism are known to be associated with resistance to radiotherapy and chemotherapy
  • 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
  • EMT is a developmental process that plays critical roles in embryogenesis, wound healing, and organ fibrosis
  • IR is known to induce stemness and metabolic alterations in cancer cells
  • 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
  • activate EMT-inducing transcription factors, including Snail/Slug, ZEB1/δEF1, ZEB2/SIP1, Twist1/2, and E12/E47
  • Loss of E-cadherin is considered a hallmark of EMT
  • 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
  • IR may increase metastasis in both the primary tumour site and in normal tissues under some circumstance
  • sublethal doses of IR have been shown to enhance the migratory and invasive behaviours of glioma cells
  • ROS are known to play an important role in IR-induced EMT
  • 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
  • hypoxia-inducible factor-1 (HIF-1) is involved in IR-induced EMT
  • Treatment with the N-acetylcysteine (NAC), a general ROS scavenger, prevents IR-induced EMT, adhesive affinity, and invasion of breast cancer cells
    • Nathan Goodyear
      Nathan Goodyear on 09 Feb 21
       
      NAC for all patients receiving radiation therapy
  • Snail has been shown to play a crucial role in IR-induced EMT, migration, and invasion
  • IR activates the p38 MAPK pathway, which contributes to the induction of Snail expression to promote EMT and invasion
  • NF-κB signalling that promotes cell migration
  • ROS promote EMT to allow cancer cells to avoid hostile environments
  • HIF-1 is a heterodimer composed of an oxygen-sensitive α subunit and a constitutively expressed β subunit.
  • Under normoxia, HIF-1α is rapidly degraded, whereas hypoxia induces stabilisation and accumulation of HIF-1α
  • levels of HIF-1α mRNA are enhanced by activation of the PI3K/Akt/mammalian target of rapamycin (mTOR)
  • IR is known to increase stabilisation and nuclear accumulation of HIF-1α, since hypoxia is a major condition for HIF-1 activation
  • IR induces vascular damage that causes hypoxia
  • ROS is implicated in IR-induced HIF-1 activation
  • IR causes the reoxygenation of hypoxic cancer cells to increase ROS production, which leads to the stabilisation and nuclear accumulation of HIF-1
  • IR increases glucose availability under reoxygenated conditions that promote HIF-1α translation by activating the Akt/mTOR pathway
  • 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
  • TGF-β signalling has been shown to play a crucial role in IR-induced EMT
  • AP-1 transcription factor is involved in IR-induced TGF-β1 expression
  • Wnt/β-catenin signalling is also implicated in IR-induced EMT
  • Notch signalling is known to be involved in IR-induced EMT
  • IR also increases Notch-1 expression [99]. Notch-1 is known to induce EMT by upregulating Snail
  • PAI-1 signalling is also implicated in IR-induced Akt activation that increases Snail levels to induce EMT
  • 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
  • ROS and RNS are also implicated in IR-induced EGFR activation
  • IR has also been shown to activate Hedgehog (Hh) signalling to induce EMT
  • 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
  • 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
  • Conventional cancer treatments kill most cancer cells, but CSCs survive due to their resistance to therapy, eventually leading to tumour relapse and metastasis
  • identification of CSCs, three types of markers are utilised: cell surface molecules, transcription factors, and signalling pathway molecules
  • CSCs express distinct and specific surface markers; commonly used ones are CD24, CD34, CD38, CD44, CD90, CD133, and ALDH
  • Transcription factors, including Oct4, Sox2, Nanog, c-Myc, and Klf4,
  • signalling pathways, including those of TGF-β, Wnt, Hedgehog, Notch, platelet-derived growth factor receptor (PDGFR), and JAK/STAT
  • microRNAs (miRNAs), including let-7, miR-22, miR-34a, miR-128, the miR-200 family, and miR-451
  • Non-CSCs can be reprogrammed to become CSCs by epigenetic and genetic changes
  • EMT-inducing transcription factors, such as Snail, ZEB1, and Twist1, are known to confer CSC properties
  • 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
  • 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
  • some CSC subpopulations arise independently of EMT
  • IR has been shown to induce the CSC phenotype in many cancers, including breast, lung, and prostate cancers, as well as melanoma
  • Genotoxic stress due to IR or chemotherapy promotes a CSC-like phenotype by increasing ROS production
  • IR has been shown to induce reprogramming of differentiated cancer cells into CSCs
  • In prostate cancer patients, radiotherapy increases the CD44+ cell population that exhibit CSC properties
  • IR also induces the re-expression of stem cell regulators, such as Sox2, Oct4, Nanog, and Klf4, to promote stemness in cancer cells
  • 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
  • STAT3 directly binds to the Snail promoter and increases Snail transcription, which induces the EMT and CSC phenotypes, in cisplatin-selected resistant cells
  • 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
  • metabolic reprogramming
  • HIF-1α, p53, and c-Myc, are known to contribute to oncogenic metabolism
  • metabolic reprogramming
  • tumour cells exhibit high mitochondrial metabolism as well as aerobic glycolysis
  • occurring within the same tumour
  • CSCs can be highly glycolytic-dependent or oxidative phosphorylation (OXPHOS)-dependen
  • mitochondrial function is crucial for maintaining CSC functionality
  • cancer cells depend on mitochondrial metabolism and increase mitochondrial production of ROS that cause pseudo-hypoxia
  • HIF-1 then enhances glycolysis
  • 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
  • lactate transporter, monocarboxylate transporter (MCT)
  • nutrient microenvironment
  • 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
  • MCT4-positive cancer cells depend on glycolysis and then efflux lactate, while MCT1-positive cells uptake lactate and rely on OXPHOS
  • metabolic heterogeneity induces a lactate shuttle between hypoxic/glycolytic cells and oxidative/aerobic tumour cells
  • 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
  • the major fraction of glucose is directed into the pentose phosphate pathway, to produce redox power through the generation of NADPH and ROS scavengers
  • HIF-1α, p53, and c-Myc, are known to contribute to oncogenic metabolism
  • 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
  • HIF-1 induces the expression of glycolytic enzymes, including the glucose transporter GLUT, hexokinase, lactate dehydrogenase (LDH), and MCT, resulting in the glycolytic switch
  • HIF-1 represses the expression of pyruvate dehydrogenase kinase (PDK), which inhibits pyruvate dehydrogenase (PDH), thereby inhibiting mitochondrial activity
  • STAT3 has been implicated in EMT-induced metabolic changes as well
  • TGF-β and Wnt play important roles in the metabolic alteration of cancer cells
  • Akt is also implicated in the glycolytic switch and in promoting cancer cell invasiveness
  • EMT, invasion, metastasis, and stemness
  • pyruvate kinase M2 (PKM2), LDH, and pyruvate carboxylase (PC), are implicated in the induction of the EMT and CSC phenotypes
  • decreased activity of PKM2 is known to promote an overall shift in metabolism to aerobic glycolysis
  • LDH catalyses the bidirectional conversion of lactate to pyruvate
  • High levels of LDHA are positively correlated with the expression of EMT and CSC markers
  • IR has been shown to induce metabolic changes in cancer cells
  • IR enhances glycolysis by upregulating GAPDH (a glycolysis enzyme), and it increases lactate production by activating LDHA, which converts pyruvate to lactate
  • IR enhances glycolysis by upregulating GAPDH (a glycolysis enzyme), and it increases lactate production by activating LDHA, which converts pyruvate to lactate
  • IR also elevates MCT1 expression that exports lactate into the extracellular environment, leading to acidification of the tumour microenvironment
  • 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
  • Lactate can activate latent TGF-
  • lactate stimulates cell migration and enhances secretion of hyaluronan from CAF that promote tumour metastasis
  • 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
  • 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.
  • immunosuppressive cells such as tumour-associated macrophages (TAM), MDSCs, and regulatory T cells, and the immunosuppressive cytokines, TGF-β and interleukin-10 (IL-10)
  • immunosuppressive cells such as tumour-associated macrophages (TAM), MDSCs, and regulatory T cells, and the immunosuppressive cytokines, TGF-β and interleukin-10 (IL-10)
  • intrinsic immunogenicity or induce tolerance
  • cancer immunoediting’
  • three phases: 1) elimination, 2) equilibrium, and 3) escape.
  • 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).
  • IR can elicit various changes in the TME, such as CAF activity-mediated ECM remodelling and fibrosis, cycling hypoxia, and an inflammatory response
  • IR activates CAFs to promote the release of growth factors and ECM modulators, including TGF-β and MMP
  • TGF-β directly influences tumour cells and CAFs, promotes tumour immune escape, and activates HIF-1 signalling
    • Nathan Goodyear
      Nathan Goodyear on 09 Feb 21
       
      And now the receipts
  • MMPs degrade ECM that facilitates angiogenesis, tumour cell invasion, and metastasis
    • Nathan Goodyear
      Nathan Goodyear on 09 Feb 21
       
      Receipts and mechanisms
  • IR also promotes MMP-2/9 activation in cancer cells to promote EMT, invasion, and metastasis
  • IR-induced Snail increases MMP-2 expression to promote EMT
  • Radiotherapy has the paradoxical side-effect of increasing tumour aggressiveness
  • 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
  • Metabolic alterations
  • oncogenic metabolism
  • elicit various changes in the TME
  • Although IR activates an antitumour immune response, this signalling is frequently suppressed by tumour escape mechanisms
  • Nathan Goodyear on 09 Feb 21
     
    Important review article.
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Pharmacological Ascorbate Radiosensitizes Pancreatic Cancer - 0 views

www.ncbi.nlm.nih.gov/...PMC4537815 cancer pancreatic cancer IV vitamin C vitamin c radiation
shared by Nathan Goodyear on 30 Jan 18 - No Cached
  • Previous studies from our laboratory have demonstrated that pharmacological ascorbate is cytotoxic to pancreatic cancer cells while normal cells are resistant
  • Ascorbate-induced cytotoxicity is mediated by the formation of H2O2 during the oxidation of ascorbate
  • the combination of IR + ascorbate increased the concentration of intracellular H2O2
  • ...17 more annotations...
  • Under steady-state conditions, intracellular GSH is maintained at millimolar concentrations, which keeps cells in a reduced environment and serves as the principal intracellular redox buffer when cells are subjected to an oxidative stressor including H2O2 (26). Glutathione peroxidase (GPx) activity catalyzes the reduction of H2O2 to water with the conversion of GSH to glutathione disulfide (GSSG). Under steady-state conditions, GSSG is recycled back to GSH by glutathione disulfide reductase using reducing equivalents from NADPH. However, under conditions of increased H2O2 flux, this recycling mechanism may become overwhelmed leading to a depletion of intracellular GSH (27, 28).
  • ascorbate radiosensitization can create an overwhelming oxidative stress to pancreatic cancer cells resulting in oxidation/depletion of the GSH intracellular redox buffer, resulting in cell death.
  • Treatment with the combination of ascorbate + IR significantly delayed tumor growth compared to controls or ascorbate alone
  • Ascorbate + IR also significantly increased overall survival compared to controls, IR alone or ascorbate alone
  • 54% of mice treated with the combination of IR + ascorbate had no measurable tumors
  • Glutathione is a measurable marker indicative of the oxidation state of the thiol redox buffer in cells. In severe systemic oxidative stress, the GSSG/2GSH couple may become oxidized, i.e. the concentration of GSH decreases and GSSG may increase because the capacity to recycle GSSG to GSH becomes rate-limiting
  • This suggests that the very high levels of pharmacological ascorbate in these experiments may have a pro-oxidant toward red blood cells as seen by a decrease in the capacity of the intracellular redox buffer
  • These data support the hypothesis that ascorbate radiosensitization does not cause an increase in oxidative damage from lipid-derived aldehydes to other organs.
  • Our current study demonstrates the potential for pharmacological ascorbate as a radiosensitizer in the treatment of pancreatic cancer.
  • pharmacological ascorbate enhances IR-induced cell killing and DNA fragmentation leading to induction of apoptosis in HL60 leukemia cells
  • pharmacological ascorbate significantly decreases clonogenic survival and inhibits the growth of all pancreatic cancer cell lines as a single agent, as well as sensitizes cancer cells to IR
  • Hurst et al. demonstrated that pharmacological ascorbate combined with IR leads to increased numbers of double-strand DNA breaks and cell cycle arrest when compared to either treatment alone
  • pharmacological ascorbate could serve as a “pro-drug” for the delivery of H2O2 to tumors
  • the double-strand breaks induced by H2O2 were more slowly repaired
  • The combination of ascorbate and IR provide two distinct mechanisms of action: ascorbate-induced toxicity due to extracellular production of H2O2 that then diffuses into cells and causes damage to DNA, protein, and lipids; and radiation-induced toxicity as a result of ROS-induced damage to DNA. In addition, redox metal metals like Fe2+ may play an important role in ascorbate-induced cytotoxicity. By catalyzing the oxidation of ascorbate, labile iron can enhance the rate of formation of H2O2; labile iron can also react with H2O2. Recently our group has demonstrated that pharmacological ascorbate and IR increase the labile iron in tumor homogenates from this murine model of pancreatic cancer
  • we demonstrated that ascorbate or IR alone decreased tumor growth, but the combination treatment further inhibited tumor growth, indicating that pharmacological ascorbate is an effective radiosensitizer in vivo
  • data suggest that pharmacological ascorbate may protect the gut locally by decreasing IR-induced damage to the crypt cells, and systemically, by ameliorating increases in TNF-α
  • Nathan Goodyear on 30 Jan 18
     
    IV vitamin C effective as radiosensitizer in pancreatic cancer.
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Hypoxia Regulates Insulin Receptor Substrate-2 Expression to Promote Breast Carcinoma C... - 0 views

cancerres.aacrjournals.org/...8894 HIF-1alpha insulin receptor substrate 2 IRS-2 Akt hypoxia breast cancer cancer
shared by Nathan Goodyear on 14 Jan 21 - No Cached
  • Nathan Goodyear on 14 Jan 21
     
    IRS-2 expression, but not IRS-1 expression, is increased by hypoxia (HIF-1alpha), which selects for tumor cells with increased metastatic potential. IRS-2 is active to mediate insulin-like growth factor I-dependent signals in hypoxia, and enhanced activation of Akt in hypoxia is dependent on IRS-2 expression. It is Akt that increases insulin receptor expression. This ties hypoxia to increase in insulin signaling and insulin receptor expression. Boom!
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The effect of leg hyperthermia using far in... [Acta Med Okayama. 2010] - PubMed - NCBI - 0 views

www.ncbi.nlm.nih.gov/...20424670 IR sauna DM diabetes TYpe II oxidative stress
shared by Nathan Goodyear on 14 Nov 11 - No Cached
  • Nathan Goodyear on 14 Nov 11
     
    IR sauna over short 2 week study shown to improve oxidative stress in patients with type 2 DM
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http://onlinelibrary.wiley.com/store/10.1113/jphysiol.2012.240952/asset/tjp5465.pdf;jse... - 0 views

onlinelibrary.wiley.com/...E5D6BF7115D91486DDF6333.f04t02 training exercise sprints running epigenetics PLIN2 PLIN5
shared by Nathan Goodyear on 30 Nov 17 - No Cached
  • Nathan Goodyear on 30 Nov 17
     
    Study finds sprint interval training increases PLIN 2 and PLIN 5 as in endurance training.  PLIN2/5 are increased and play role in intramuscluar triglyceride breakdown.  Increased IMTG is found in IR.  This aids insulin resistance.  Other studies have found that SIT increased PLIN5 > ET.  Exercise impacts muscle and fat through epigenetics.
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Original Articles: Comparison of Insulin Action on Glucose versus Potassium Uptake in H... - 0 views

www.ncbi.nlm.nih.gov/...PMC3133473 diabetes insulin resistance potassium hyperkalemia glucose insulin
shared by Nathan Goodyear on 31 Oct 17 - No Cached
  • When treating hyperkalemia, insulin remains efficacious in diabetics and nondiabetics and one does not need to resort to b-agonists, and diabetics do not require different doses of insulin to shift potassium
  • the commonly encountered “insulin-resistant” patients actually have preserved insulin-induced potassium disposal, one wonders why their high insulin levels are not causing hypokalemia
  • insulin independently regulates glucose and potassium uptake into cells and this independence explains why in noninsulin-dependent diabetic insulin resistance leads to impaired insulin uptake into cells but has no effect on the cell's potassium disposal
  • ...9 more annotations...
  • insulin suppresses glycogenolysis, gluconeogenesis, lipolysis and fatty acid release, and protein catabolism and is the principal hormone that stimulates glucose uptake into mainly skeletal muscle and to a certain extent adipocytes
  • Plasma [K+] is a major determinant of the resting potential of all cells
  • Hyperkalemia and hypokalemia are silent yet fatal disturbances because of their arrhythmogenic potentials
  • Basal insulin maintains fasting plasma [K+] within the normal range
  • When insulin levels are suppressed, plasma [K+] rises and pronounced hyperkalemia develops after a potassium load
  • Potassium is a well proven insulin secretagogue
  • Insulin is a key defender against exogenous potassium load by using intracellular buffering to minimize hyperkalemia before renal excretion
  • Hyperkalemia is often encountered in patients with diabetes
  • The insulin-deficient state in type 1 diabetes predisposes to hyperkalemia because of an impaired ability of potassium to enter cells. During hyperglycemic hypertonic states in type 1 and type 2 diabetics, potassium is carried out of cells by convective flux as the most abundant intracellular cation
  • Nathan Goodyear on 31 Oct 17
     
    good review of the potassium, glucose, insulin relationship mostly in diabetes.  In diabetes, hyperkalemia is present due to the hyperglycemia and the associated exchange.  Inuslin independantly regulates potassium and glucose intake into the cell.  INterestingly, in IR found in diabetes, the hyperkalemia is the norm, which should cause hypokalemia--the authors were perplexed by this finding.
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Testosterone: a metabolic hormone in health and disease - 0 views

joe.endocrinology-journals.org/...R25.full male hormone hormones testosterone hypogonadal-obesity-adipocytokine hypothesis
shared by Nathan Goodyear on 08 May 13 - No Cached
  • E2 and the inflammatory adipocytokines tumour necrosis factor α (TNFα) and interleukin 6 (IL6) inhibit hypothalamic production of GNRH and subsequent release of LH and FSH from the pituitary
  • Leptin, an adipose-derived hormone with a well-known role in regulation of body weight and food intake, also induces LH release under normal conditions via stimulation of hypothalamic GNRH neurons
  • In human obesity, whereby adipocytes are producing elevated amounts of leptin, the hypothalamic–pituitary axis becomes leptin resistant
  • ...39 more annotations...
  • there is evidence from animal studies that leptin resistance, inflammation and oestrogens inhibit neuronal release of kisspeptin
  • Beyond hypothalamic action, leptin also directly inhibits the stimulatory action of gonadotrophins on the Leydig cells of the testis to decrease testosterone production; therefore, elevated leptin levels in obesity may further diminish androgen status
  • increasing insulin resistance assessed by glucose tolerence test and hypoglycemic clamp was shown to be associated with a decrease in Leydig cell testosterone secretion in men
  • ADT for the treatment of prostatic carcinoma in some large epidemiological studies has been shown to be associated with an increased risk of developing MetS and T2DM
  • Non-diabetic men undergoing androgen ablation show increased occurrence of new-onset diabetes and demonstrate elevated insulin levels and worsening glycaemic control
  • Prostate cancer patients with pre-existing T2DM show a further deterioration of insulin resistance and worsening of diabetic control following ADT
  • The response to testosterone replacement of insulin sensitivity is in part dependent on the androgen receptor (AR)
  • Low levels of testosterone have been associated with an atherogenic lipoprotein profile, characterised by high LDL and triglyceride levels
  • a positive correlation between serum testosterone and HDL has been reported in both healthy and diabetic men
  • up to 70% of the body's insulin sensitivity is accounted for by muscle
  • Testosterone deficiency is associated with a decrease in lean body mass
  • relative muscle mass is inversely associated with insulin resistance and pre-diabetes
  • GLUT4 and IRS1 were up-regulated in cultured adipocytes and skeletal muscle cells following testosterone treatment at low dose and short-time incubations
  • local conversion of testosterone to DHT and activation of AR may be important for glucose uptake
  • inverse correlation between testosterone levels and adverse mitochondrial function
  • orchidectomy of male Wistar rats and associated testosterone deficiency induced increased absorption of glucose from the intestine
  • (Kelley & Mandarino 2000). Frederiksen et al. (2012a) recently demonstrated that testosterone may influence components of metabolic flexibility as 6 months of transdermal testosterone treatment in aging men with low–normal bioavailable testosterone levels increased lipid oxidation and decreased glucose oxidation during the fasting state.
  • Decreased lipid oxidation coupled with diet-induced chronic FA elevation is linked to increased accumulation of myocellular lipid, in particular diacylglycerol and/or ceramide in myocytes
  • In the Chang human adult liver cell line, insulin receptor mRNA expression was significantly increased following exposure to testosterone
  • Testosterone deprivation via castration of male rats led to decreased expression of Glut4 in liver tissue, as well as adipose and muscle
  • oestrogen was found to increase the expression of insulin receptors in insulin-resistant HepG2 human liver cell line
  • FFA decrease hepatic insulin binding and extraction, increase hepatic gluconeogenesis and increase hepatic insulin resistance.
  • Only one, albeit large-scale, population-based cross-sectional study reports an association between low serum testosterone concentrations and hepatic steatosis in men (Völzke et al. 2010)
  • This suggests that testosterone may confer some of its beneficial effects on hepatic lipid metabolism via conversion to E2 and subsequent activation of ERα.
  • hypogonadal men exhibiting a reduced lean body mass and an increased fat mass, abdominal or central obesity
  • visceral adipose tissue was inversely correlated with bioavailable testosterone
  • there was no change in visceral fat mass in aged men with low testosterone levels following 6 months of transdermal TRT, yet subcutaneous fat mass was significantly reduced in both the thigh and the abdominal areas when analysed by MRI (Frederiksen et al. 2012b)
  • ADT of prostate cancer patients increased both visceral and subcutaneous abdominal fat in a 12-month prospective observational study (Hamilton et al. 2011)
  • Catecholamines are the major lipolysis regulating hormones in man and regulate adipocyte lipolysis through activation of adenylate cyclase to produce cAMP
  • deficiency of androgen action decreases lipolysis and is primarily responsible for the induction of obesity (Yanase et al. 2008)
  • may be some regional differences in the action of testosterone on subcutaneous and visceral adipose function
  • proinflammatory adipocytokines IL1, IL6 and TNFα are increased in obesity with a downstream effect that stimulates liver production of CRP
  • observational evidence suggests that IL1β, IL6, TNFα and CRP are inversely associated with serum testosterone levels in patients
  • TRT has been reported to significantly reduce these proinflammatory mediators
  • This suggests a role for AR in the metabolic actions of testosterone on fat accumulation and adipose tissue inflammatory response
  • testosterone treatment may have beneficial effects on preventing the pathogenesis of obesity by inhibiting adipogenesis, decreasing triglyceride uptake and storage, increasing lipolysis, influencing lipoprotein content and function and may directly reduce fat mass and increase muscle mass
  • Early interventional studies suggest that TRT in hypogonadal men with T2DM and/or MetS has beneficial effects on lipids, adiposity and parameters of insulin sensitivity and glucose control
  • Evidence that whole-body insulin sensitivity is reduced in testosterone deficiency and increases with testosterone replacement supports a key role of this hormone in glucose and lipid metabolism
  • Impaired insulin sensitivity in these three tissues is characterised by defects in insulin-stimulated glucose transport activity, in particular into skeletal muscle, impaired insulin-mediated inhibition of hepatic glucose production and stimulation of glycogen synthesis in liver, and a reduced ability of insulin to inhibit lipolysis in adipose tissue
  • Nathan Goodyear on 08 May 13
     
    Great review of the Hypogonadal-obesity-adipocytokine hypothesis.
1More

Hypoadiponectinemia in Obesity and Type 2 Diabetes: Close Association with Insulin Resi... - 0 views

jcem.endojournals.org/...1930.short obesity diabetes type II 2 insulin resistance IR adiponectin
shared by Nathan Goodyear on 17 Mar 12 - No Cached
  • Nathan Goodyear on 17 Mar 12
     
    obesity and type II diabetes found to be associated with low adiponectin and elevated insulin as found in insulin resistance.  This study revealed the inverse relationship of adiponectin and insulin resistance.  The interesting thing is that inflammation causes insulin resistance.  Here you can see the inflammation-insulin resistance-low adiponectin-obesity-diabetes link.
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High Glucose-Induced Expression of Proinflammatory Cytokine and Chemokine Genes in Mono... - 0 views

diabetes.diabetesjournals.org/...1256.abstract glucose diabetes IR insulin resistance inflammation TNF-alpha MCP-1 IL-1B
shared by Nathan Goodyear on 11 Jun 12 - No Cached
  • HG significantly increased the expression of monocyte chemoattractant protein-1 (MCP-1), TNF-α, β2-integrin, interleukin-1β, and others. HG treatment increased transcription of the MCP-1 gene, MCP-1 protein levels, and adhesion of THP-1 cells to endothelial cells. HG-induced MCP-1 mRNA expression and monocyte adhesion were blocked by specific inhibitors of oxidant stress, protein kinase C, ERK1/2, and p38 mitogen-activated protein kinases
  • Nathan Goodyear on 11 Jun 12
     
    High glucose associated with significant increase in inflammatory signaling.
1More

Testosterone replacement therapy improves insulin resistance, glycaemic control, viscer... - 1 views

www.eje-online.org/...899.full testosterone diabetes replacement therapy insulin resistance weight-loss men glucose control IR low T hyperlipidemia
shared by Nathan Goodyear on 11 Feb 12 - No Cached
  • Nathan Goodyear on 11 Feb 12
     
    Testosterone therapy shown to improve insulin resistance, glucose control, hyperlipidemia, and aids weight loss in men with type II diabetes
1More

The Dark Side of Testosterone Deficiency: II. Type 2 Diabetes and Insulin Resistance --... - 1 views

www.andrologyjournal.org/...23 low T testosterone insulin resistance IR type II diabetes DM metabolic syndrome fat mortality
shared by Nathan Goodyear on 11 Feb 12 - No Cached
  • Nathan Goodyear on 11 Feb 12
     
    low Testosterone associated with insulin resistance, type II diabetes, metabolic syndrome, and increased fat.  These will all translate to increased mortality.
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Obesity - Abstract of article: 11[beta]-Hydroxysteroid Dehydrogenase 2 Activity Is Elev... - 0 views

www.nature.com/...oby2008218a.html 11-betaHSD type I II adipose tissue obese IR insulin resistance sensitivity
shared by Nathan Goodyear on 13 Mar 12 - No Cached
  • Nathan Goodyear on 13 Mar 12
     
    11-betaHSD type II increased in adipose tissue.  This correlates with insulin sensitivity.
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Relationship of visceral adipose tissue and glucose disposal is independent of sex in b... - 0 views

ajpendo.physiology.org/...E425.short visceral fat adipose tissue adiposity IR insulin resistance glucose metabolic dysfunction
shared by Nathan Goodyear on 30 Mar 12 - No Cached
  • an inverse nonlinear relationship existed between glucose disposal and visceral fat
  • Nathan Goodyear on 30 Mar 12
     
    Increase in visceral fat reduces glucose "disposal".  Translated: as visceral adiposity increases, associated insulin resistance increases glucose levels and all associated metabolic dysfunction.
1More

The Dark Side of Testosterone Deficiency: II. Type 2 Diabetes and Insulin Resistance - ... - 0 views

onlinelibrary.wiley.com/...full low T Testosterone diabetes insulin resistance IR metabolic syndrome metabolic syndrome men male hormone hormones
shared by Nathan Goodyear on 30 Jan 14 - No Cached
  • Nathan Goodyear on 30 Jan 14
     
    low Testosterone linked to insulin resistance, type II Diabetes, and increased  metabolic syndrome.  Low T is linked to increased visceral fat in this study.  
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Effect of Testosterone Treatment on Glucose Metabolism in men With Type 2 Diabetes: A R... - 0 views

care.diabetesjournals.org/...dc13-2845.abstract diabetes type II diabetes low T Testosterone glucose insulin metabolism men male hormone hormones HOMA-IR fat mass lean
shared by Nathan Goodyear on 15 May 14 - No Cached
  • Nathan Goodyear on 15 May 14
     
    Study finds no improvement with glucose control in diabetics.  This study looked at moderately controlled diabetes. Studies have previously shown that poorly controlled diabetes definitely benefits more than those with more mild glucose control problems.  Additionally, the Testosterone levels in this study would not have met the definition of low T by other studies.  So, the question is did these men need T?  Second, did the authors design the study long enough to see changes in the insulin sensitivity and glucose control?  Abstract only available and thus I don't have access to that information.  Third, and this might support the 2nd point, increased lean mass and decreased fat mass was found.  This points to positive metabolic change.  Would this have, given more time, resulted in improved glucose control? No change in visceral adiposity was seen.  This finding, also, is not new.  Testosterone therapy does not improve visceral adiposity.  Though, increasing fat adiposity, low Testosterone, and associated increase in systemic inflammatory cytokine production results in visceral adiposity, Testosterone therapy does reverse the visceral adiposity.  
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Frontiers | Impact of the gut microbiota on the development of obesity and type 2 diabe... - 0 views

journal.frontiersin.org/...full LPS lipopolysaccharides IR insulin resistance obesity diabetes gut gut bacteria gut microbiome gut microbiota
shared by Nathan Goodyear on 20 Jun 17 - No Cached
  • Nathan Goodyear on 20 Jun 17
     
    great review on how LPS from the gut causes systemic insulin resistance
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Plant-Based Nutritional Supplementation Attenuates LPS-Induced Low-Grade Systemic Activ... - 0 views

www.ncbi.nlm.nih.gov/...PMC7826722 TLR4 inflammation LPS metabolic endotoxemia plant-based nutrition plant-based diet plant-based
shared by Nathan Goodyear on 03 Sep 21 - No Cached
  • consumption of this particular diet for at least a 2-month period helped to reduce the outcomes of both acute and chronic inflammation induced by LPS.
  • chronic inflammation compromised both glucose and insulin tolerance, which is normally seen in certain chronic metabolic diseases
  • LPS resulted in an increase in neopterin levels, which is a marker for immune system activation
  • ...6 more annotations...
  • diet enriched in fruits and vegetables (and consequently phytochemicals) was able to reverse the process and maintain and even elevate insulin sensitivity and glucose tolerance
  • LPS-mediated effects are related to an increase in TLR4 levels that triggers the activation of nuclear factor-kB (NF-kB), a transcription factor that activates a cascade of inflammatory mediators [41]. These factors control the transcription of inflammatory mediators, such as IL-1β, IL-6, TNF-α, TNF-β, INF-α, INFβ, INF-γ
  • Inflammation can alter insulin action and give rise to diabetes and obesity by blocking insulin receptor downstream events, impairing insulin receptor substrate 1 (IRS-1) activation and phosphatidylinositol 3-kinase-dependent (PI3K) pathways, therefore compromising insulin signaling
  • systemic inflammation (generated by LPS) also increased neopterin levels in the urine and resulted in altered neuronal activity by decreasing dopamine (DA) metabolism
  • an increase in neopterin levels has been recognized a sensitive biomarker for immune system activation
  • Our experiments denoted that these diets were able to diminish inflammatory mediators and oxidative damage
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