Non-small-cell lung cancers with kinase domain mutations in the epidermal growth factor receptor are sensitive to ionizing radiation.
Non-small cell lung cancers (NSCLCs) bearing mutations in the tyrosine kinase domain (TKD) of the epidermal growth factor receptor (EGFR) often exhibit dramatic sensitivity to the EGFR tyrosine kinase inhibitors gefitinib and erlotinib. Ionizing radiation (IR) is frequently used in the treatment of NSCLC, but little is known how lung tumor-acquired EGFR mutations affect responses to IR. Because this is of great clinical importance, we investigated and found that clonogenic survival of mutant EGFR NSCLCs in response to IR was reduced 500- to 1,000-fold compared with wild-type (WT) EGFR NSCLCs. Exogenous expression of either the L858R point mutant or the DeltaE746-E750 deletion mutant form of EGFR in immortalized human bronchial epithelial cells, p53 WT NSCLC (A549), or p53-null NSCLC (NCI-H1299) resulted in dramatically increased sensitivity to IR. We show that the majority of mutant EGFR NSCLCs, including those that contain the secondary gefitinib resistance T790M mutation, exhibit characteristics consistent with a radiosensitive phenotype, which include delayed DNA repair kinetics, defective IR-induced arrest in DNA synthesis or mitosis, and pronounced increases in apoptosis or micronuclei. Thus, understanding how activating mutations in the TKD domain of EGFR contribute to radiosensitivity should provide new insight into effective treatment of NSCLC with radiotherapy and perhaps avoid emergence of single agent drug resistance.
Das
Amit K
AK
Division of Molecular Radiation Biology, Department of Radiation Oncology, University of Texas Southwestern Medical Center, 2201 Inwood Road, NC 7.208, Mail Code 9187, Dallas, TX 75390, USA.
Sato
Mitsuo
M
Story
Michael D
MD
Peyton
Michael
M
Graves
Robert
R
Redpath
Stella
S
Girard
Luc
L
Gazdar
Adi F
AF
Shay
Jerry W
JW
Minna
John D
JD
Nirodi
Chaitanya S
CS
D017209:Apoptosis / Q000235:genetics / Q000528:radiation effects; D001610:Beta Particles; D002289:Carcinoma, Non-Small-Cell Lung / Q000201:enzymology / Q000235:genetics* / Q000473:pathology; D004260:DNA Repair / Q000235:genetics; D004261:DNA Replication / Q000235:genetics / Q000528:radiation effects; D019008:Drug Resistance, Neoplasm / Q000235:genetics; D066246:ErbB Receptors / Q000737:chemistry / Q000502:physiology*; D005091:Exons / Q000235:genetics; D005720:Gamma Rays; D000077156:Gefitinib; D018773:Genes, erbB-1; D016158:Genes, p53; D006801:Humans; D008175:Lung Neoplasms / Q000201:enzymology / Q000235:genetics* / Q000473:pathology; D009154:Mutation; D009363:Neoplasm Proteins / Q000737:chemistry / Q000502:physiology*; D017434:Protein Structure, Tertiary; D011799:Quinazolines / Q000494:pharmacology; D011836:Radiation Tolerance / Q000235:genetics; D011993:Recombinant Fusion Proteins / Q000502:physiology; D017384:Sequence Deletion; D014407:Tumor Cells, Cultured / Q000201:enzymology / Q000528:radiation effects; D014410:Tumor Stem Cell Assay
D009363:Neoplasm Proteins; D011799:Quinazolines; D011993:Recombinant Fusion Proteins; C512478:EGFR protein, human; D066246:ErbB Receptors; D000077156:Gefitinib