Characterizing The Effects of Ascorbic Acid and Hyperbaric Oxygen on Glioblastoma Cells

Abstract

There is emerging evidence supporting the use of intravenous ascorbic acid (AA) as a pro‐oxidative, non‐toxic adjuvant therapy. Before AA is implicated in the clinic, however, more research needs to be conducted to better understand AA's mechanisms of action, and to determine what cancers would be most amenable to this adjunctive therapy. When administered intravenously, AA can achieve pharmacological, millimolar concentrations (~0.3–20 mM) and act as a pro‐oxidant in tumorous tissue, contrary to its antioxidant effects observed with oral administration, which produces micromolar, physiological concentrations (≤0.1 mM). Our study aims to evaluate the effects of pharmacological AA on glioblastoma cells (VM‐M3 and U87), and to see if another pro‐oxidative therapy, hyperbaric oxygen (HBOT), can sensitize cells to treatment. We hypothesize that 1‐hour treatment with AA will decrease VM‐M3 and U87 cell viability, and that co‐treatment with antioxidant N‐Acetylcysteine (NAC) will attenuate cell death. We also hypothesize that hydrogen peroxide mediates AA‐induced VM‐M3 and U87 cell death, and thus that exogenous catalase treatment will attenuate this effect. It was found that 1‐hour treatment with pharmacological AA decreased viability in both VM‐M3 and U87 cells, with VM‐M3 cells exhibiting greater sensitivity to treatment (assessed with crystal violet staining). HBOT did not enhance AA‐induced cytotoxicity in U87 cells; however, HBOT did sensitize VM‐M3 cells to AA treatment. Additionally, 1‐hour co‐treatment with AA and NAC, as well as AA and catalase, rescued cell death in U87 and VM‐M3 cells, suggesting that AA‐induced oxidative stress is mediated by hydrogen peroxide. This study also investigates the effects of AA and HBOT on HIF‐1 alpha, catalase, and transferrin receptor protein expression, yielding further insight into the pro‐oxidative role of AA in cancer.Support or Funding InformationWork supported by: American Physiological Society Undergraduate Research Excellence Fellowship (APS UGREF); Foundation (501c3); Metabolic Therapy and Cancer Research Account (#250244); Scivation: Florida High Tech Corridor Funding (#MED052‐0061361).This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.