title: Enhancement of radiosensitivity in head and neck cancer cells by ZD1839 ('IRESSA'), a selective epidermal growth factor receptor tyrosine kinase inhibitor.
abstract: Overexpression of epidermal growth factor receptor (EGFR) is frequently observed in many solid tumor types, including head and neck squamous cell carcinomas (HNSCC). Recent laboratory experiments have demonstrated that high EGFR levels correlate with increased tumor resistance to radiation. This study investigated the relationship between EGFR expression levels and radiosensitivity in 5 HNSCC cell lines (HSC2, HSC3, HSC4, SCC25, and Ca9-22) and whether treatment with ZD1839 ('Iressa'), a selective EGFR-tyrosine kinase inhibitor (TKI), would improve tumor cell response to radiotherapy. ZD1839 suppressed the growth of HNSCC cell lines in a dose- and time-dependent manner. Radiosensitivity of these HNSCC cell lines, assessed by a clonogenic survival assay, differed greatly and the expression of EGFR varied. EGFR expression levels (EGFR numbers/cell) correlated with increased tumor resistance to radiation (f[x]= 4.54 X, R2 = 0.715; f[x]: EGFR numbers/cell, X: radiosensitivity; D10). Following exposure of the HNSCC cells to 1.0 microM ZD1839 and radiation (0-10 Gy), greater than additive growth inhibitory effects were observed. These results suggest that ZD1839 could enhance tumor radiosensitivity and inhibit tumor growth after radiation, indicating that this combination could have clinical potential in the treatment of patients with head and neck cancer.
authors.affiliation: Department of Oral and Maxillofacial Surgery, Ehime University School of Medicine, Ehime, Japan. satoru@m.ehime-u.ac.jp
authors.forename: Satoru
authors.initials: S
authors.lastname: Shintani
authors.forename: Akihisa
authors.initials: A
authors.lastname: Kiyota
authors.forename: Mariko
authors.initials: M
authors.lastname: Mihara
authors.forename: Tomoki
authors.initials: T
authors.lastname: Sumida
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Kayahara
authors.forename: Koh-ichi
authors.initials: K
authors.lastname: Nakashiro
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Hamakawa
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology*; D002294:Carcinoma, Squamous Cell / Q000188:drug therapy* / Q000378:metabolism / Q000532:radiotherapy*; D045744:Cell Line, Tumor; D002470:Cell Survival; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D066246:ErbB Receptors / Q000037:antagonists & inhibitors* / Q000378:metabolism; D005434:Flow Cytometry; D000077156:Gefitinib; D006258:Head and Neck Neoplasms / Q000188:drug therapy* / Q000378:metabolism / Q000532:radiotherapy*; D006801:Humans; D011799:Quinazolines / Q000494:pharmacology*; D011836:Radiation Tolerance / Q000187:drug effects*
chemical_list: D000970:Antineoplastic Agents; D004791:Enzyme Inhibitors; D011799:Quinazolines; D066246:ErbB Receptors; D000077156:Gefitinib