USE OF FINE-NEEDLE ASPIRATES FOR THE IDENTIFICATION OF MUTATIONS WITHIN THE ESTROGEN RECEPTOR-a HORMONE-BINDING DOMAIN IN TAMOXIFEN-RESISTANT HUMAN BREAST CARCINOMAS

Blitvich B.J., Ward B.K., Frost F.A., Ingram D.M., Byme M.J., Ratajczak T.

Summary. We investigated the hypothesis that mutations within estrogen receptor-a (ERa) may be one of the mechanisms of breast carcinoma progression to a hormone-independent phenotype. Fine-needle aspirations were collected from patients with tamoxifen resistant metastatic breast carcinomas. Total RNA was isolated and the entire ERa hormone-binding domain (HBD) amplified by RT-PCR using 4 pairs of overlapping primers. PCR products were screened for mutations by single-stranded conformational polymorphism (SSCP) analysis and DNA sequencing. Although no mutations were detected by SSCP analysis, two silent polymorphisms were identified by automated DNA sequencing at codons 538 [GAC - GAT (Asp)] and 594 [ACA - ACG (Thr)]. The codon 538 variant was detected in tumour specimens at a low frequency whereas the codon 594 variant was detected in patients and healthy controls at a similar frequency. Exon 7-deleted variant was also detected in all tumour specimens. Fine-needle aspirations, in conjunction with RT-PCR, could be a rapid and reliable method for the mutational analysis of the ERa HBD. However, mutations within the ERa HBD do not appear to represent a significant mechanism in the development of antiestrogen resistance.