EGFR sequence variations and real-time quantitative polymerase chain reaction analysis of gene dosage in brain metastases of solid tumors.
Clinical response to Gefitinib (Iressa, ZD1839) has been found to be associated with somatic mutations, primarily of exons 18-21, of the epidermal growth factor receptor gene (EGFR) in non-small cell lung cancer (NSCLC). Evidence of a positive response was also reported recently on a patient with brain metastasis from NSCLC. On the other hand, amplification of EGFR appears to be associated with a poor prognosis. To determine whether EGFR mutations and amplification are involved in the tumorigenesis of brain metastases, we performed polymerase chain reaction/single-strand conformation polymorphism to examine exons 1, 2, and 7-26 of EGFR in a series of 18 brain metastases. The metastases derived from malignant melanoma (three cases), lung carcinoma (six cases), breast carcinoma (three cases), ovarian carcinoma (two cases), and one each from colon, kidney, bladder, and undifferentiated carcinoma. In addition to several sequence polymorphisms, we identified two mutations on E19 consisting of 18-base pair (bp) deletions: 2423-24440del and 2426-2443del. These mutations presented in lesions derived from kidney carcinoma and lung adenocarcinoma. By real-time quantitaive polymerase chain reaction technique, we determined the amplification/overdose status of EGFR by analyzing exons 11 and 25. Amplification (5- to 100-fold) was identified in three tumors, and overdose (low-level gene amplification corresponding to increases of 1- to 5-fold) presented in four additional metastases. These findings suggest that EGFR mutations and polymorphisms are not exclusively present in metastases derived from lung carcinoma. Accordingly, targeting of EGFR to determine molecular alterations of this gene may be useful in the management of patients with brain metastases.
Franco-Hernandez
Carmen
C
Molecular Oncogenetics Laboratory, Research Unit, University Hospital La Paz, Paseo Castellana 261, 28046 Madrid, Spain.
Martinez-Glez
Victor
V
Arjona
Dolores
D
de Campos
Jose M
JM
Isla
Alberto
A
Gutierrez
Manuel
M
Vaquero
Jesus
J
Rey
Juan A
JA
D000328:Adult; D000368:Aged; D000595:Amino Acid Sequence; D001483:Base Sequence; D001932:Brain Neoplasms / Q000235:genetics / Q000556:secondary*; D004252:DNA Mutational Analysis; D004273:DNA, Neoplasm / Q000737:chemistry / Q000235:genetics; D066246:ErbB Receptors / Q000235:genetics*; D005260:Female; D018628:Gene Dosage; D006801:Humans; D008297:Male; D008875:Middle Aged; D016254:Mutagenesis, Insertional; D009154:Mutation; D009369:Neoplasms / Q000235:genetics / Q000473:pathology*; D016133:Polymerase Chain Reaction / Q000379:methods*; D011110:Polymorphism, Genetic; D018807:Polymorphism, Single-Stranded Conformational; D017384:Sequence Deletion
D004273:DNA, Neoplasm; D066246:ErbB Receptors