Establishment and characterization of a model of acquired resistance to epidermal growth factor receptor targeting agents in human cancer cells.
OBJECTIVE
The epidermal growth factor receptor (EGFR) is recognized as a key mediator of proliferation and progression in many human tumors. A series of EGFR-specific inhibitors have recently gained Food and Drug Administration approval in oncology. These strategies of EGFR inhibition have shown major tumor regressions in approximately 10% to 20% of advanced cancer patients. Many tumors, however, eventually manifest resistance to treatment. Efforts to better understand the underlying mechanisms of acquired resistance to EGFR inhibitors, and potential strategies to overcome resistance, are greatly needed.


METHODS
To develop cell lines with acquired resistance to EGFR inhibitors we utilized the human head and neck squamous cell carcinoma tumor cell line SCC-1. Cells were treated with increasing concentrations of cetuximab, gefitinib, or erlotinib, and characterized for the molecular changes in the EGFR inhibitor-resistant lines relative to the EGFR inhibitor-sensitive lines.


RESULTS
EGFR inhibitor-resistant lines were able to maintain their resistant phenotype in both drug-free medium and in athymic nude mouse xenografts. In addition, EGFR inhibitor-resistant lines showed a markedly increased proliferation rate. EGFR inhibitor-resistant lines had elevated levels of phosphorylated EGFR, mitogen-activated protein kinase, AKT, and signal transducer and activator of transcription 3, which were associated with reduced apoptotic capacity. Subsequent in vivo experiments indicated enhanced angiogenic potential in EGFR inhibitor-resistant lines. Finally, EGFR inhibitor-resistant lines showed cross-resistance to ionizing radiation.


CONCLUSIONS
We have developed EGFR inhibitor-resistant human head and neck squamous cell carcinoma cell lines. This model provides a valuable preclinical tool to investigate molecular mechanisms of acquired resistance to EGFR blockade.
Benavente
Sergio
S
Department of Human Oncology, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin 53792-0600, USA.
Huang
Shyhmin
S
Armstrong
Eric A
EA
Chi
Alexander
A
Hsu
Kun-Tai
KT
Wheeler
Deric L
DL
Harari
Paul M
PM
D000818:Animals; D000911:Antibodies, Monoclonal / Q000494:pharmacology; D061067:Antibodies, Monoclonal, Humanized; D000970:Antineoplastic Agents / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects; D014408:Biomarkers, Tumor / Q000235:genetics / Q000378:metabolism*; D002294:Carcinoma, Squamous Cell / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D002453:Cell Cycle / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D000068818:Cetuximab; D019008:Drug Resistance, Neoplasm; D066246:ErbB Receptors / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism*; D000069347:Erlotinib Hydrochloride; D000077156:Gefitinib; D006258:Head and Neck Neoplasms / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D006801:Humans; D015151:Immunoblotting; D051379:Mice; D008819:Mice, Nude; D008954:Models, Biological; D009389:Neovascularization, Pathologic; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D011799:Quinazolines / Q000494:pharmacology; D011829:Radiation Dosage; D014407:Tumor Cells, Cultured
D000911:Antibodies, Monoclonal; D061067:Antibodies, Monoclonal, Humanized; D000970:Antineoplastic Agents; D014408:Biomarkers, Tumor; D047428:Protein Kinase Inhibitors; D011799:Quinazolines; D000069347:Erlotinib Hydrochloride; C512478:EGFR protein, human; D066246:ErbB Receptors; D000068818:Cetuximab; D000077156:Gefitinib