High-dose parenteral ascorbate enhanced chemosensitivity of ovarian cancer and reduced toxicity of chemotherapy.
Abstract
Ascorbate (vitamin C)
was an early, unorthodox therapy for cancer, with an outstanding safety
profile and anecdotal clinical benefit. Because oral ascorbate was
ineffective in two cancer clinical trials, ascorbate was abandoned by
conventional oncology but continued to be used in complementary and
alternative medicine. Recent studies provide rationale for reexamining
ascorbate treatment. Because of marked pharmacokinetic differences,
intravenous, but not oral, ascorbate produces millimolar concentrations
both in blood and in tissues, killing cancer cells without harming
normal tissues. In the interstitial fluid surrounding tumor cells,
millimolar concentrations of ascorbate exert local pro-oxidant effects
by mediating hydrogen peroxide (H(2)O(2)) formation, which kills cancer
cells. We investigated downstream mechanisms of ascorbate-induced cell
death. Data show that millimolar ascorbate, acting as a pro-oxidant,
induced DNA damage and depleted cellular adenosine triphosphate (ATP),
activated the ataxia telangiectasia mutated (ATM)/adenosine
monophosphate-activated protein kinase (AMPK) pathway, and resulted in
mammalian target of rapamycin (mTOR) inhibition and death in ovarian
cancer cells. The combination of parenteral ascorbate with the
conventional chemotherapeutic agents carboplatin and paclitaxel
synergistically inhibited ovarian cancer in mouse models and reduced
chemotherapy-associated toxicity in patients with ovarian cancer. On the
basis of its potential benefit and minimal toxicity, examination of
intravenous ascorbate in combination with standard chemotherapy is
justified in larger clinical trials.
source: http://www.ncbi.nlm.nih.gov/pubmed/?term=sciTranslMed+2014%2C+6+vitamin+C
source: http://www.ncbi.nlm.nih.gov/pubmed/?term=sciTranslMed+2014%2C+6+vitamin+C
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