Abstract P2-01-12: Circulating tumor cells and Epithelial Mesenchymal Transition in primary breast cancer patients.

Abstract

Abstract Background: Circulating tumor cells (CTCs) are prognostic in breast cancer (BC) patients. CTCs represent a heterogeneous population of cells with different phenotypes and biological value. Epithelial-mesenchymal transition (EMT) gives rise to cells with stem cell-like properties with increased chemotherapy resistance and may be responsible for undetection of CTC by conventional methods in a fraction of patients with early or advanced breast cancer. The aim of this study was to characterize CTCs based on the expression of epithelial and mesenchymal markers in non-metastatic breast cancer patients before surgery. Methods: This prospective ongoing translational study consists of 36 patients with non-metastatic breast cancer. CTCs were detected before surgery, before 1st cycle and before 2nd cycle of adjuvant therapy. Herein, we present preliminary data related to CTCs detection before surgery. Isolated peripheral blood mononuclear cells (PBMC) were depleted of cells of hematopoietic origin (CD45+) using RossetteSep kit (StemCell Technologies) negative selection with anti-CD45 antibody. RNA extracted from CD45-depleted (CD45−) PBMC was interrogated for expression of EMT-inducing transcription factors (TWIST1, SNAIL1, SLUG, FOXC2) and epithelial (CK19, EpCAM) gene transcripts by quantitative reverse transcription-PCR. Expressions of gene transcripts in CD45- PBMC from patients were compared to those of CD45- PBMC of 30 healthy donors (HD). Results: Median age was 62 year (range: 40–80 years). TWIST1, SNAIL1, SLUG, FOXC2, CK19 and EpCAM were overexpressed in CD45- PBMC in 2.8%, 2.8%, 11.1%, 13.9%, 19.4% and 2.8% respectively. Totally, CTCs were detected in 36.2% of patients. CTCs with only epithelial markers were present in peripheral blood of 5.6% patients; CTC with EMT phenotype were present in 13.9% of patients, while in 16.7% of patients CTCs exhibited both epithelial and mesenchymal markers. Overexpression of different EMT-related transcription factors in peripheral blood samples were mutually exclusive. There was no association between the presence of CTCs and analyzed clinico-pathological variables. Conclusions: CTCs with EMT phenotypes are more prevalent compared to CTCs with epithelial phenotype in early breast cancer patients before surgery, and EMT genes may be involved in the dissemination of CTCs. These data support the concept of CTCs heterogeneity in breast cancer patients. Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P2-01-12.