title: Genetic and chemical targeting of epithelial-restricted with serine box reduces EGF receptor and potentiates the efficacy of afatinib.
abstract: EGF receptor (EGFR) is elevated in more than 90% of head and neck squamous cell carcinoma (HNSCC). However, a majority of patients with HNSCC do not respond to anti-EGFR therapeutics. Insensitivity to EGFR inhibitors may be due to kinase-independent actions of EGFR and/or activation of Her2. Strategies to reduce EGFR and Her2 protein levels in concert may be an optimal approach to enhance the efficacy of current anti-EGFR molecules. In this study, knockdown of epithelial-restricted with serine box (ESX) decreased EGFR and Her2 promoter activity, expression, and levels. ESX was elevated in primary HNSCC tumors and associated with increased EGFR and Her2. Genetic ablation of ESX decreased EGFR and Her2 levels and enhanced the antiproliferative effects of EGFR/Her2 tyrosine kinase inhibitors (TKI), lapatinib and afatinib. Biphenyl isoxazolidine, a novel small-molecule ESX inhibitor, reduced EGFR and Her2 levels and potentiated the antiproliferative efficacy of afatinib. Single-agent biphenyl isoxazolidine retarded the in vivo tumorigenicity of CAL27 cells. Importantly, the combination of biphenyl isoxazolidine and afatinib was significantly superior in vivo and resulted in a 100% response rate with a 94% reduction in tumor volume. Targeting EGFR/Her2 levels with an ESX inhibitor and EGFR/Her2 kinase activity with a TKI simultaneously is a highly active therapeutic approach to manage HNSCC. Our work provides evidence to support the further development of ESX inhibitors as an adjuvant to enhance the response rate of patients with HNSCC to current anti-EGFR/Her2 therapeutics.
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, The Ohio State University Wexner Medical Center, Columbus, OH 43210, USA.
authors.forename: Manchao
authors.initials: M
authors.lastname: Zhang
authors.forename: Christopher E
authors.initials: CE
authors.lastname: Taylor
authors.forename: Longzhu
authors.initials: L
authors.lastname: Piao
authors.forename: Jharna
authors.initials: J
authors.lastname: Datta
authors.forename: Paul A
authors.initials: PA
authors.lastname: Bruno
authors.forename: Sanjay
authors.initials: S
authors.lastname: Bhave
authors.forename: Tizhi
authors.initials: T
authors.lastname: Su
authors.forename: James C
authors.initials: JC
authors.lastname: Lang
authors.forename: Xiujie
authors.initials: X
authors.lastname: Xie
authors.forename: Theodoros N
authors.initials: TN
authors.lastname: Teknos
authors.forename: Anna K
authors.initials: AK
authors.lastname: Mapp
authors.forename: Quintin
authors.initials: Q
authors.lastname: Pan
mesh_terms: D000077716:Afatinib; D000818:Animals; D002294:Carcinoma, Squamous Cell / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D045744:Cell Line, Tumor; D002471:Cell Transformation, Neoplastic / Q000235:genetics / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000037:antagonists & inhibitors* / Q000235:genetics* / Q000378:metabolism; D004195:Disease Models, Animal; D019008:Drug Resistance, Neoplasm / Q000235:genetics; D066246:ErbB Receptors / Q000235:genetics* / Q000378:metabolism; D005260:Female; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D055785:Gene Knockdown Techniques; D006258:Head and Neck Neoplasms / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D064593:Heterografts; D006801:Humans; D051379:Mice; D047428:Protein Kinase Inhibitors / Q000494:pharmacology*; D011518:Proto-Oncogene Proteins / Q000037:antagonists & inhibitors* / Q000235:genetics* / Q000378:metabolism; D050783:Proto-Oncogene Proteins c-ets; D011799:Quinazolines / Q000494:pharmacology*; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D000077195:Squamous Cell Carcinoma of Head and Neck; D014157:Transcription Factors / Q000037:antagonists & inhibitors* / Q000235:genetics* / Q000378:metabolism
chemical_list: D000077716:Afatinib; D004268:DNA-Binding Proteins; D066246:ErbB Receptors; D047428:Protein Kinase Inhibitors; D011518:Proto-Oncogene Proteins; D050783:Proto-Oncogene Proteins c-ets; D011799:Quinazolines; D018719:Erb-b2 Receptor Tyrosine Kinases; D014157:Transcription Factors; C105529:ELF3 protein, human