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Nathan Goodyear

Hormetic dose response to L-ascorbic acid as an anti-cancer drug in colorectal cancer cell lines according to SVCT-2 expression | Scientific Reports - 0 views

www.nature.com/...s41598-018-29386-7

hermetic dose response prooxidative low dose vitamin C vitamin sodium dependent vitamin C transporter High dose IV vitamin C SVCT C high dose vitamin C

shared by Nathan Goodyear on 11 Aug 22 - No Cached
  • Nathan Goodyear on 11 Aug 22
     
    Low dose vitamin C, via SVCT, increases tumor proliferation; whereas high dose decreases tumor proliferation.
Nathan Goodyear

Frontiers | Artesunate Suppresses the Proliferation and Development of Estrogen Receptor-α-Positive Endometrial Cancer in HAND2-Dependent Pathway - 0 views

www.frontiersin.org/...full

ER alpha ER-alpha uterine cancer endometrial cancer cancer artesunate mTOR

shared by Nathan Goodyear on 02 Sep 22 - No Cached
  • Nathan Goodyear on 02 Sep 22
     
    artesunate down regulates ER-alpha expression
Nathan Goodyear

Ascorbate in pharmacologic concentrations selectively generates ascorbate radical and hydrogen peroxide in extracellular fluid in vivo - 0 views

www.ncbi.nlm.nih.gov/...PMC1885574

vitamin C ascorbic acid Cancer

shared by Nathan Goodyear on 05 Mar 18 - No Cached
  • Proposed mechanism
  • The data show that pharmacologic ascorbate concentrations produced Asc•− selectively in extracellular fluid compared with blood and that H2O2 formation occurred when Asc•− concentrations were >100 nM in extracellular fluid.
  • These data validate the hypothesis that ascorbate is a prodrug for selective delivery of reactive species to the extravascular space
  • ...22 more annotations...
  • pharmacologic ascorbate as a prooxidant drug for therapeutic use.
  • Recently we reported that pharmacologic ascorbic acid concentrations produced H2O2 concentrations of ≥25 μM, causing cancer cell death in vitro
  • We found that H2O2 concentrations generated in vivo were those that caused cancer cell death in vitro
  • When ascorbate was given parenterally, Asc•−, the product of a loss of one electron from ascorbate, was detected preferentially in extracellular fluid compared with blood
  • Asc•− generation in extracellular fluid depended on the ascorbate dose and the resulting concentrations
  • With i.v. administration of ascorbate, Asc•− concentrations were as much as 12-fold greater in extracellular fluid compared to blood and approached 250 nM
  • In blood, such Asc•− concentrations were never produced and were always <50 nM
  • These data are all consistent with the hypothesis that pharmacologic ascorbate concentrations in vivo serve as a prodrug for selective delivery of H2O2 to the extracellular space
  • After oral ingestion, control of intracellular and extracellular ascorbate concentrations is mediated by three mechanisms: intestinal absorption, tissue transport, and renal reabsorption
  • intestinal absorption, or bioavailability, declines at doses >200 mg
    • Nathan Goodyear
      Nathan Goodyear on 05 Mar 18
       
      significant limitation of gut absorption of vitamin C--at 200 mg po.
  • corresponding to plasma concentrations of ≈60 μM
    • Nathan Goodyear
      Nathan Goodyear on 05 Mar 18
       
      equates to 0.06 mM.  Max blood levels found with po AA dosing has been 0.22 mM
  • at approximately this concentration, the ascorbate tissue transporter SVCT2 approaches Vmax, and tissues appear to be saturated
    • Nathan Goodyear
      Nathan Goodyear on 05 Mar 18
       
      SVCT2 Rc in gut reach max binding.
  • also at ≈60 μM, renal reabsorption approaches saturation, and excess ascorbate is excreted in urine
  • Parenteral administration bypasses tight control
  • When tight control is bypassed, H2O2 forms in the extracellular space
  • in vivo validation of ascorbate as a prodrug for selective H2O2 formation
  • Temporarily bypassing tight control with parenteral administration of ascorbate allows H2O2 to form in discrete time periods only, decreasing likelihood of harm, and provides a pharmacologic basis for therapeutic use of i.v. ascorbate
  • H2O2 formation results in selective cytotoxicity
  • Tumor cells are killed with exposure to H2O2 for ≤30 min
  • In vitro, killing is mediated by H2O2 rather than Asc•−
  • In addition to cancer treatment, another potential therapeutic use is for treatment of infections. H2O2 concentrations of 25–50 μM are bacteriostatic
  • virally infected cells may also be candidates
  • Nathan Goodyear on 05 Mar 18
     
    follow up invivo study to previous study from 2005.  Here, the authors prove their hypothesis that ascorbate is a prodrug for delivery of H2O2.
Nathan Goodyear

We're Not "DON" Yet: Optimal Dosing and Prodrug Delivery of 6-Diazo-5-oxo-L-norleucine - PMC - 0 views

www.ncbi.nlm.nih.gov/...PMC6130910

glutamine DON dosing cancer

shared by Nathan Goodyear on 17 Mar 24 - No Cached
  • Glutamine is the most abundant amino acid in blood
  • Rapidly proliferating healthy cells (GI epithelium, lymphocytes) or cells under physiologic stress have increased demand for glutamine
  • Glutamine is transported into cells by one of multiple amino acid transporters (e.g. ASCT2, BOAT2), several of which are thought to be upregulated in cancer cells
  • ...10 more annotations...
  • it is hydrolyzed to glutamate and ammonia by glutaminase (‘glutaminolysis’)
  • Glutamate, produced from glutamine by glutaminase and glutamine amidotransferase activities, may be further metabolized to alpha ketoglutarate and provide a carbon skeleton source for the mitochondrial tricarboxylic acid cycle (TCA cycle)
  • Glutamine-derived glutamate is also involved in the synthesis of the reducing equivalent glutathione, vital to maintaining cellular redox status
  • Many tumors become largely dependent on glutamine to provide carbon and nitrogen building blocks needed for proliferation
  • In cancer model systems, Eagle and colleagues first demonstrated tumor cells in culture require supplementation with exogenous glutamine for efficient proliferation
  • It was subsequently shown that when deprived of glutamine tumor cells undergo apoptosis
  • The most well-characterized oncogene to regulate glutamine metabolism is MYC (9), which enhances glutaminase expression, upregulates glutamine transporters, and enhances glutamine utilization in energy production and biosynthesis
  • Other pro-tumorigenic regulators such as KRAS and mTOR, as well as tumor suppressors (p53, VHL) have also been associated with alterations in glutamine metabolism
  • Tumor cells are highly adaptable and alter nutrient uptake and metabolic networks to resist single agent glutaminase inhibition
  • cells in the microenvironment of several tumor types upregulate glutamine production, thereby enabling tumor cells to escape glutaminase inhibition
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