title: MyD88-Dependent Signaling Decreases the Antitumor Efficacy of Epidermal Growth Factor Receptor Inhibition in Head and Neck Cancer Cells.
abstract: EGFR is upregulated in the majority of head and neck squamous cell carcinomas (HNSCC). However, many patients with HNSCC respond poorly to the EGFR inhibitors (EGFRI) cetuximab and erlotinib, despite tumor expression of EGFR. Gene expression analysis of erlotinib-treated HNSCC cells revealed an upregulation of genes involved in MyD88-dependent signaling compared with their respective vehicle-treated cell lines. We therefore investigated whether MyD88-dependent signaling may reduce the antitumor efficacy of EGFRIs in HNSCC. Erlotinib significantly upregulated IL6 secretion in HNSCC cell lines, which our laboratory previously reported to result in reduced drug efficacy. Suppression of MyD88 expression blocked erlotinib-induced IL6 secretion in vitro and increased the antitumor activity of erlotinib in vivo. There was little evidence of Toll-like receptor or IL18 receptor involvement in erlotinib-induced IL6 secretion. However, suppression of IL1R signaling significantly reduced erlotinib-induced IL6 production. A time-dependent increase of IL1α but not IL1β was observed in response to erlotinib treatment, and IL1α blockade significantly increased the antitumor activity of erlotinib and cetuximab in vivo. A pan-caspase inhibitor reduced erlotinib-induced IL1α secretion, suggesting that IL1α was released because of cell death. Human HNSCC tumors showed higher IL1α mRNA levels compared with matched normal tissue, and IL1α was found to be negatively correlated with survival in patients with HNSCC. Overall, the IL1α/IL1R/MYD88/IL6 pathway may be responsible for the reduced antitumor efficacy of erlotinib and other EGFRIs, and blockade of IL1 signaling may improve the efficacy of EGFRIs in the treatment of HNSCC.
authors.affiliation: Department of Pathology, The University of Iowa, Iowa City, Iowa. Roy J. and Lucille A. Carver College of Medicine, The University of Iowa, Iowa City, Iowa.
authors.forename: Adam T
authors.initials: AT
authors.lastname: Koch
authors.affiliation: Department of Pathology, The University of Iowa, Iowa City, Iowa. Roy J. and Lucille A. Carver College of Medicine, The University of Iowa, Iowa City, Iowa.
authors.forename: Laurie
authors.initials: L
authors.lastname: Love-Homan
authors.affiliation: Roy J. and Lucille A. Carver College of Medicine, The University of Iowa, Iowa City, Iowa. Free Radical and Radiation Biology Program, Department of Radiation Oncology, The University of Iowa, Iowa City, Iowa.
authors.forename: Madelyn
authors.initials: M
authors.lastname: Espinosa-Cotton
authors.affiliation: Roy J. and Lucille A. Carver College of Medicine, The University of Iowa, Iowa City, Iowa. Interdisciplinary Human Toxicology Program, The University of Iowa, Iowa City, Iowa.
authors.forename: Aditya
authors.initials: A
authors.lastname: Stanam
authors.affiliation: Department of Pathology, The University of Iowa, Iowa City, Iowa. Roy J. and Lucille A. Carver College of Medicine, The University of Iowa, Iowa City, Iowa. Free Radical and Radiation Biology Program, Department of Radiation Oncology, The University of Iowa, Iowa City, Iowa. Interdisciplinary Human Toxicology Program, The University of Iowa, Iowa City, Iowa. Holden Comprehensive Cancer Center, The University of Iowa, Iowa City, Iowa. andrean-simons@uiowa.edu.
authors.forename: Andrean L
authors.initials: AL
authors.lastname: Simons
mesh_terms: D000818:Animals; D061067:Antibodies, Monoclonal, Humanized / Q000494:pharmacology / Q000627:therapeutic use*; D000970:Antineoplastic Agents / Q000494:pharmacology / Q000627:therapeutic use; D017209:Apoptosis / Q000187:drug effects / Q000235:genetics; D002294:Carcinoma, Squamous Cell / Q000188:drug therapy* / Q000235:genetics; D000068818:Cetuximab; D019008:Drug Resistance, Neoplasm / Q000235:genetics*; D066246:ErbB Receptors / Q000037:antagonists & inhibitors*; D000069347:Erlotinib Hydrochloride; D005260:Female; D006258:Head and Neck Neoplasms / Q000188:drug therapy* / Q000235:genetics; D006801:Humans; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D008819:Mice, Nude; D053594:Myeloid Differentiation Factor 88 / Q000502:physiology*; D011799:Quinazolines / Q000494:pharmacology / Q000627:therapeutic use*; D015398:Signal Transduction / Q000235:genetics; D000077195:Squamous Cell Carcinoma of Head and Neck; D016896:Treatment Outcome; D014407:Tumor Cells, Cultured
chemical_list: D061067:Antibodies, Monoclonal, Humanized; D000970:Antineoplastic Agents; C507779:MYD88 protein, human; D053594:Myeloid Differentiation Factor 88; D011799:Quinazolines; D000069347:Erlotinib Hydrochloride; D066246:ErbB Receptors; D000068818:Cetuximab