title: Radiopotentiation of human brain tumor cells by sodium phenylacetate.
abstract: Phenylacetate (PA) inhibits the growth of tumor cells in vitro and in vivo and shows promise as a relatively nontoxic agent for cancer treatment. A recent report shows that prolonged exposure of cells to low concentrations of PA can enhance the radiation response of brain tumor cells in vitro, opening up the possibility of using this drug to improve the radiation therapy of brain tumor patients. We investigated the cytotoxicity produced by sodium phenylacetate (NaPA) alone and in combination with X-rays in SF-767 human glioblastoma cells and in two medulloblastoma cell lines, Masden and Daoy. Exposure of all three cell lines to relatively low concentrations of NaPA for up to 5 days did not enhance the subsequent cell killing produced by X-irradiation. However, enhanced cell killing was achieved by exposing either oxic or hypoxic cells to relatively high drug concentrations ( > 50-70 mM) for 1 h immediately before X-irradiation. Because central nervous system toxicity can occur in humans at serum concentrations of approximately 6 mM PA, translation of these results into clinical trials will likely require local drug-delivery strategies to achieve drug concentrations that can enhance the radiation response. The safety of such an approach with this drug has not been demonstrated.
authors.affiliation: Brain Tumor Research Center of the Department of Neurological Surgery, School of Medicine, University of California, San Francisco 94143-0520, USA.
authors.forename: T
authors.initials: T
authors.lastname: Ozawa
authors.forename: R M
authors.initials: RM
authors.lastname: Lu
authors.forename: L J
authors.initials: LJ
authors.lastname: Hu
authors.forename: K R
authors.initials: KR
authors.lastname: Lamborn
authors.forename: M D
authors.initials: MD
authors.lastname: Prados
authors.forename: D F
authors.initials: DF
authors.lastname: Deen
mesh_terms: D001932:Brain Neoplasms; D002455:Cell Division / Q000187:drug effects / Q000528:radiation effects; D015687:Cell Hypoxia; D002470:Cell Survival / Q000187:drug effects / Q000528:radiation effects; D005909:Glioblastoma; D006801:Humans; D008527:Medulloblastoma; D010648:Phenylacetates / Q000494:pharmacology*; D011838:Radiation-Sensitizing Agents / Q000494:pharmacology*; D014407:Tumor Cells, Cultured / Q000187:drug effects / Q000528:radiation effects
chemical_list: D010648:Phenylacetates; D011838:Radiation-Sensitizing Agents; C025136:phenylacetic acid