Abstract |
Reactive oxygen species (ROS) can transduce intracellular signals or damage macromolecules, including mutational activation of the K-ras oncogene, particularly in A/J mice, which are reported to be highly sensitive to the ROS-initiating teratogen phenytoin. Here, we determined in embryo culture whether the Ras pathway mediated phenytoin embryopathy at the protein or gene level. Embryos from pregnant inbred A/J dams and outbred CD-1 dams were cultured with a therapeutic concentration of phenytoin, with or without alpha-hydroxyfarnesylphosphonic acid, an inhibitor of the enzyme farnesyl- protein transferase, which is required for posttranslational Ras activation. A/J and CD-1 embryos were similarly susceptible to phenytoin embryopathies, with reductions in anterior neuropore closure, turning, yolk sac diameter, and somite development (p < 0.05). The farnesyl- protein transferase inhibitor blocked phenytoin embryotoxicity in A/J embryos for all parameters except yolk sac diameter (p < 0.05) and completely blocked embryotoxicity in CD-1 embryos (p < 0.05). Embryonic DNA did not show phenytoin-initiated mutations in codon 12 of the K-ras gene in either A/J or CD-1 embryos, but phenytoin substantially increased the levels of GTP-bound Ras in both CD-1 and A/J embryos. These results provide the first direct evidence that Ras proteins may be involved in the teratogenicity of phenytoin, likely via a mechanism other than mutational activation.
|
Authors | Louise M Winn, Peter G Wells |
Journal | Toxicology and applied pharmacology
(Toxicol Appl Pharmacol)
Vol. 184
Issue 3
Pg. 144-52
(Nov 01 2002)
ISSN: 0041-008X [Print] United States |
PMID | 12460742
(Publication Type: Comparative Study, Journal Article, Research Support, Non-U.S. Gov't)
|
Chemical References |
- (alpha-hydroxyfarnesyl)phosphonic acid
- Anticonvulsants
- Organophosphonates
- Teratogens
- Farnesol
- Phenytoin
- DNA
- Oncogene Protein p21(ras)
|
Topics |
- Abnormalities, Drug-Induced
(genetics)
- Animals
- Anticonvulsants
(toxicity)
- DNA
(analysis)
- DNA Mutational Analysis
- Dose-Response Relationship, Drug
- Drug Interactions
- Embryo, Mammalian
(drug effects, metabolism)
- Embryonic and Fetal Development
(drug effects)
- Farnesol
(analogs & derivatives, pharmacology)
- Female
- Gene Expression Regulation, Developmental
- Genes, ras
- Mice
- Mice, Inbred A
- Oncogene Protein p21(ras)
(metabolism)
- Organ Culture Techniques
- Organophosphonates
(pharmacology)
- Phenytoin
(toxicity)
- Pregnancy
- Signal Transduction
- Species Specificity
- Teratogens
|