95P Comparison of Expression Levels of Twist, Snail and Slug in Primary Tumors and Lymph Node Metastases in Breast Cancer Patients

Abstract

ABSTRACT Introduction The expression of prognostic markers including the regulators of epithelial to mesenchymal transition (EMT) can change during the course of the disease. Therefore, reassessment of these markers at the time of disease progression might help to optimize their prognostic value. In this context, characterization of metastatic tissue could be of relevance. The aim of this study was to evaluate and compare the expression of master regulators of EMT TWIST, SNAIL and SLUG in primary breast cancer tumors and their corresponding lymph node metastases. Materials and methods Fresh-frozen or formalin-fixed paraffin-embedded (FFPE) primary tumor samples and their corresponding FFPE lymph node metastases from 21, stage II-III breast cancer patients were examined. Expression of TWIST, SNAIL and SLUG was measured by RT-qPCR method using Ct approach. Based on the median gene expression level samples were classified as positive or negative for a particular marker. Results from primary tumor samples and metastases were compared. Expression levels of transcription factors (TFs) in lymph node metastases were correlated with patients' outcome. Results FFPE samples from lymph node metastases showed elevated levels of all TFs when compared to FFPE primary tumor samples. Ratios between the average expression levels were 7:1, 6:1 and 3:1 for TWIST, SNAIL and SLUG, respectively. Primary tumors paired with corresponding lymph node metastases were concordant in 52% for each gene. In lymph node metastases elevated expression of TWIST and SNAIL was associated with decreased overall survival (p = 0.045 and p = 0.022, respectively) and disease free survival (p = 0.02 and p = 0.01, respectively). Conclusions All TFs had elevated expression levels in lymph node metastases when compared to primary tumors, with TWIST being most significantly upregulated. These findings could be explicable by recent studies showing the critical role of TWIST in the development of metastases. TWIST and SNAIL expression in lymph node metastases was found to be marker of poor prognosis in accordance to the fact that EMT is thought to confer aggressive behavior of the tumor. Disclosure All authors have declared no conflicts of interest.