Somatic mutation in the EGFR gene in ovarian carcinoma detected by SSCP and direct sequencing

Abstract

5063 Background: Recently, mutations of the EGFR kinase domain have been described in adenocarcinoma of lung and are particularly common in non-smoking females of Japan. These tumors are more responsive to blockade of the EGFR TK domain than non-mutant tumors. Ovarian tumors are known to express EGFR but the frequency of EGFR mutation at this site has not been explored. Methods: We have searched for mutations in the EGFR gene in ovarian carcinoma in two ways, first by single stranded conformation polymorphism (SSCP) analysis of appropriately amplified DNA from microdissected paraffin sections and then by direct forward and reverse sequencing of the DNA for mutations in exons 18, 19 and 21. Results: There was poor correlation between the two methods. By direct sequencing and evaluation of sequence chromatograms by Mutation Surveyor, mutations were detected in 8 of 79 patients (10.1%). Three of the mutations have been previously described in NSCLC including two in-frame deletions in exon 19 (codons 746–750) and one point mutation in exon 21 (L858R). Previously undescribed point mutations resulting in amino substitutions were found in an additional 5 patients including two patients with multiple mutations. These point mutations included 3 in exon 18 (Q701R, L704S and T725A) and 5 in exon 21 (N830G, R832C, T852M, I853V and Q868D). Deletions were detected by SSCP but point mutations were not detected. Conclusions: We conclude that a low but definite frequency of mutation in the EGFR tyrosine kinase domain occurs in ovarian carcinoma in the Japanese population and that these tumors may be targeted by EGFR blockers. SSCP can detect multibase deletions but is an unreliable method for detection of point mutations. No significant financial relationships to disclose.