The oxidative mechanism of action of ortho-quinone inhibitors of protein-tyrosine phosphatase α is mediated by hydrogen peroxide

• Published in: Archives of biochemistry and biophysics Vol. 429; no. 1; pp. 30 - 41
• Main Authors: Bova, Michael P., Mattson, Matthew N., Vasile, Stefan, Tam, Danny, Holsinger, Leslie, Bremer, Meire, Hui, Terence, McMahon, Gerald, Rice, Audie, Fukuto, Jon M.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.09.2004
• Subjects: Animals; Catalase; Cell Movement - drug effects; Cell Movement - physiology; Dose-Response Relationship, Drug; DTT; Enzyme Activation; Hydrogen peroxide; Hydrogen Peroxide - chemistry; Hydrogen Peroxide - metabolism; Kinetics; Mice; NIH 3T3 Cells; ortho-Quinone inhibitors; Oxidation-Reduction; Protein Tyrosine Phosphatases - antagonists & inhibitors; Protein Tyrosine Phosphatases - chemistry; Protein Tyrosine Phosphatases - metabolism; Protein-tyrosine phosphatase α; Quinones - chemistry; Quinones - pharmacology; Receptor-Like Protein Tyrosine Phosphatases, Class 4; ortho-Quinone inhibitors; Protein-tyrosine phosphatase α; Hydrogen peroxide; Catalase; DTT
• ISSN: 0003-9861; 1096-0384
• DOI: 10.1016/j.abb.2004.05.010

Here, we report the identification and characterization of five ortho-quinone inhibitors of PTPα. We observed that the potency of these compounds in biochemical assays was markedly enhanced by the presence of DTT. A kinetic analysis suggested that they were functioning as irreversible inhibitors and that the inhibition was targeted to the catalytic site of PTPα. The inhibition observed by these compounds was sensitive to superoxide dismutase and catalase, suggesting that reactive oxygen species may be mediators of their inhibition. We observed that in the presence of DTT, these compounds would produce up to 2.5 mM hydrogen peroxide (H 2O 2). The levels of H 2O 2 produced were sufficient to completely inactivate PTPα. In contrast, without a reducing agent the compounds did not generate H 2O 2 and showed little activity towards PTPα. In addition, these compounds inhibited PTPα-dependent cell spreading in NIH 3T3 cells at concentrations that were similar to their activity in biochemical assays. The biological implications of these results are discussed as they support growing evidence that H 2O 2 is a key regulator of PTPs.