title: Tyrosine phosphorylation of the human glutathione S-transferase P1 by epidermal growth factor receptor.
abstract: Epidermal growth factor receptor (EGFR) gene amplification, mutations, and/or aberrant activation are frequent abnormalities in malignant gliomas and other human cancers and have been associated with an aggressive clinical course and a poor therapeutic outcome. Elevated glutathione S-transferase P1 (GSTP1), a major drug-metabolizing and stress response signaling protein, is also associated with drug resistance and poor clinical outcome in gliomas and other cancers. Here, we provide evidence that GSTP1 is a downstream EGFR target and that EGFR binds to and phosphorylates tyrosine residues in the GSTP1 protein in vitro and in vivo. Mass spectrometry and mutagenesis analyses in a cell-free system and in gliomas cells identified Tyr-7 and Tyr-198 as major EGFR-specific phospho-acceptor residues in the GSTP1 protein. The phosphorylation increased GSTP1 enzymatic activity significantly, and computer-based modeling showed a corresponding increase in electronegativity of the GSTP1 active site. In human glioma and breast cancer cells, epidermal growth factor stimulation rapidly increased GSTP1 tyrosine phosphorylation and decreased cisplatin sensitivity. Lapatinib, a clinically active EGFR inhibitor, significantly reversed the epidermal growth factor-induced cisplatin resistance. These data define phosphorylation and activation of GSTP1 by EGFR as a novel, heretofore unrecognized component of the EGFR signaling network and a novel mechanism of tumor drug resistance, particularly in tumors with elevated GSTP1 and/or activated EGFR.
authors.affiliation: From the Departments of Surgery, Durham, North Carolina 27710.
authors.forename: Tatsunori
authors.initials: T
authors.lastname: Okamura
authors.affiliation: From the Departments of Surgery, Durham, North Carolina 27710.
authors.forename: Simendra
authors.initials: S
authors.lastname: Singh
authors.affiliation: Department of Pharmaceutical Sciences, College of Pharmacy, University of Tennessee Health Sciences Center, Memphis, Tennessee 38163.
authors.forename: John
authors.initials: J
authors.lastname: Buolamwini
authors.affiliation: Pharmacology, Durham, North Carolina 27710.
authors.forename: Timothy
authors.initials: T
authors.lastname: Haystead
authors.affiliation: From the Departments of Surgery, Durham, North Carolina 27710.
authors.forename: Henry
authors.initials: H
authors.lastname: Friedman
authors.affiliation: Pathology, Duke Comprehensive Cancer Center, and the Preston Robert Tisch Brain Tumor Center, Duke University, Durham, North Carolina 27710.
authors.forename: Darell
authors.initials: D
authors.lastname: Bigner
authors.affiliation: From the Departments of Surgery, Durham, North Carolina 27710. Electronic address: francis.aliosman@duke.edu.
authors.forename: Francis
authors.initials: F
authors.lastname: Ali-Osman
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology; D001483:Base Sequence; D001665:Binding Sites; D001943:Breast Neoplasms / Q000188:drug therapy / Q000235:genetics / Q000378:metabolism; D045744:Cell Line, Tumor; D002474:Cell-Free System; D002945:Cisplatin / Q000494:pharmacology; D019008:Drug Resistance, Neoplasm / Q000187:drug effects; D004789:Enzyme Activation; D066246:ErbB Receptors / Q000037:antagonists & inhibitors / Q000378:metabolism*; D005260:Female; D005910:Glioma / Q000188:drug therapy / Q000235:genetics / Q000378:metabolism; D051549:Glutathione S-Transferase pi / Q000037:antagonists & inhibitors / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D000077341:Lapatinib; D051379:Mice; D008819:Mice, Nude; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009368:Neoplasm Transplantation; D010766:Phosphorylation; D011487:Protein Conformation; D011799:Quinazolines / Q000494:pharmacology; D034741:RNA, Small Interfering / Q000235:genetics; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D055672:Static Electricity; D014183:Transplantation, Heterologous; D014443:Tyrosine / Q000737:chemistry
chemical_list: D000970:Antineoplastic Agents; D011799:Quinazolines; D034741:RNA, Small Interfering; D011994:Recombinant Proteins; D000077341:Lapatinib; D014443:Tyrosine; C496556:GSTP1 protein, human; D051549:Glutathione S-Transferase pi; D066246:ErbB Receptors; D002945:Cisplatin