title: Ezrin Enhances EGFR Signaling and Modulates Erlotinib Sensitivity in Non-Small Cell Lung Cancer Cells.
abstract: Ezrin is a scaffolding protein that is involved in oncogenesis by linking cytoskeletal and membrane proteins. Ezrin interacts with epidermal growth factor receptor (EGFR) in the cell membrane, but little is known about the effects of this interaction on EGFR signaling pathway. In this study, we established the biological and functional significance of ezrin-EGFR interaction in non-small cell lung cancer (NSCLC) cells. Endogenous ezrin and EGRF interaction was confirmed by co-immunoprecipitation and immunofluorescent staining. When expression of ezrin was inhibited, EGFR activity and phosphorylation levels of downstream signaling pathway proteins ERK and STAT3 were decreased. Cell fractionation experiments revealed that nuclear EGFR was significantly diminished in ezrin-knockdown cells. Consequently, mRNA levels of EGFR target genes AURKA, COX-2, cyclin D1, and iNOS were decreased in ezrin-depleted cells. A small molecule inhibitor of ezrin, NSC305787, reduced EGF-induced phosphorylation of EGFR and downstream target proteins, EGFR nuclear translocation, and mRNA levels of nuclear EGFR target genes similar to ezrin suppression. NSC305787 showed synergism with erlotinib in wild-type EGFR-expressing NSCLC cells, whereas no synergy was observed in EGFR-null cells. Phosphorylation of ezrin on Y146 was found as an enhancer of ezrin-EGFR interaction and required for increased proliferation, colony formation, and drug resistance to erlotinib. These findings suggest that ezrin-EGFR interaction augments oncogenic functions of EGFR and that targeting ezrin may provide a potential novel approach to overcome erlotinib resistance in NSCLC cells.
authors.affiliation: Department of Oncology, Georgetown University Medical Center, Washington, DC, USA; Department of Molecular Medicine, Institute of Health Sciences, Dokuz Eylul University, Izmir, Turkey.
authors.forename: Yasemin
authors.initials: Y
authors.lastname: Saygideğer-Kont
authors.affiliation: Department of Oncology, Georgetown University Medical Center, Washington, DC, USA.
authors.forename: Tsion Zewdu
authors.initials: TZ
authors.lastname: Minas
authors.affiliation: Department of Oncology, Georgetown University Medical Center, Washington, DC, USA.
authors.forename: Hayden
authors.initials: H
authors.lastname: Jones
authors.affiliation: Department of Oncology, Georgetown University Medical Center, Washington, DC, USA.
authors.forename: Sarah
authors.initials: S
authors.lastname: Hour
authors.affiliation: Department of Oncology, Georgetown University Medical Center, Washington, DC, USA.
authors.forename: Haydar
authors.initials: H
authors.lastname: Çelik
authors.affiliation: Department of Oncology, Georgetown University Medical Center, Washington, DC, USA.
authors.forename: Idil
authors.initials: I
authors.lastname: Temel
authors.affiliation: Department of Oncology, Georgetown University Medical Center, Washington, DC, USA.
authors.forename: Jenny
authors.initials: J
authors.lastname: Han
authors.affiliation: Department of Medical Biology, Dokuz Eylul University School of Medicine, Izmir, Turkey.
authors.forename: Nese
authors.initials: N
authors.lastname: Atabey
authors.affiliation: Department of Oncology, Georgetown University Medical Center, Washington, DC, USA.
authors.forename: Hayriye Verda
authors.initials: HV
authors.lastname: Erkizan
authors.affiliation: Department of Oncology, Georgetown University Medical Center, Washington, DC, USA.
authors.forename: Jeffrey A
authors.initials: JA
authors.lastname: Toretsky
authors.affiliation: Department of Oncology, Georgetown University Medical Center, Washington, DC, USA. Electronic address: au26@georgetown.edu.
authors.forename: Aykut
authors.initials: A
authors.lastname: Üren
mesh_terms: D017209:Apoptosis / Q000187:drug effects; D002289:Carcinoma, Non-Small-Cell Lung / Q000188:drug therapy* / Q000235:genetics / Q000473:pathology; D045744:Cell Line, Tumor; D003598:Cytoskeletal Proteins / Q000235:genetics / Q000378:metabolism*; D019008:Drug Resistance, Neoplasm / Q000235:genetics*; D066246:ErbB Receptors / Q000235:genetics / Q000378:metabolism*; D000069347:Erlotinib Hydrochloride / Q000008:administration & dosage; D006801:Humans; D009154:Mutation; D009363:Neoplasm Proteins / Q000096:biosynthesis; D010766:Phosphorylation; D011485:Protein Binding / Q000187:drug effects; D047428:Protein Kinase Inhibitors / Q000008:administration & dosage; D050796:STAT3 Transcription Factor / Q000096:biosynthesis; D015398:Signal Transduction / Q000187:drug effects; D000099149:Ezrin
chemical_list: D003598:Cytoskeletal Proteins; D066246:ErbB Receptors; D000069347:Erlotinib Hydrochloride; D009363:Neoplasm Proteins; D047428:Protein Kinase Inhibitors; D050796:STAT3 Transcription Factor; D000099149:Ezrin; C512478:EGFR protein, human