Abstract 1465: Prognostic significance of stem cell and EMT phenotype in Circulating Tumor Cells.

Abstract

Abstract Background: Circulating tumor cells (CTCs) are associated with prognosis and can be used as a liquid biopsy for repeated follow up examinations. The subpopulation of CTCs that successfully establish distant metastases share EMT and stemness features. These cells have been found to be associated with resistance to anti-cancer therapies and treatment failure. Patients and methods: Peripheral blood (20 mL in EDTA) was obtained and after density gradient centrifugation, immunomagnetic Ber-EP4 coated capture beads were used to enrich for epithelial cells from 102 patients with early breast cancer and 23 patients with verified metastasis. Messenger RNA was isolated from enriched epithelial cells using oligo (dT)25 coated magnetic beads. After cDNA synthesis the expression of CK-19, MAGE-A3, HER-2, PBGD and CD24, CD44, ALDH1, HPRT was tested, using two different quadruplex RT-qPCR assays. Moreover we performed RT-qPCR for the expression of TWIST1, hMammaglobin and hTERT α+β+. Results: The presence of circulating tumor cells was evaluated using CK-19, MAGE-A3, HER-2, hTERT α+β+, and mammaglobin gene transcripts. In 102 operable breast cancer patients 31 patients (30.4%) were found positive for the presence of CTCs. CTC biomarkers were significantly correlated with lymph nodes (P=0.032). In the CTC+ group, 10 patients (32.3%) were positive for TWIST1 and 16 (51.6%) were positive for CD44+/CD24-/low and ALDH1+ cell phenotype. We found a significant correlation between HER2 negative tumors with TWIST1 expression (P=0.027) and Stem Cell phenotype (P=0.012). The detection of both EMT and Stem Cell characteristics was associated with shorter disease-free survival (P=0.024). In the CTC positive group of patients with verified metastasis (39.1%) 1 patient (11.1%) was positive for TWIST1 and 4 (44.4%) were positive for CD44+/CD24-/low and ALDH1+ cell phenotype. The detection of CK19+, Stem Cell and Stem Cell and/or EMT phenotype was associated with shorter overall-free survival (P=0.036, P=0.001 and P=0.002). Discussion: CTCs in breast cancer patients share both stem cell and/or EMT phenotype. The detection and molecular characterization of CTCs with an EMT or stem cell-like characteristics could be a powerful diagnostic tool for the determination of prognosis and designing new therapeutic drugs for the elimination of minimal residual disease. Citation Format: Areti D. Strati, Vasilis Georgoulias, Evi Lianidou. Prognostic significance of stem cell and EMT phenotype in Circulating Tumor Cells. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 1465. doi:10.1158/1538-7445.AM2013-1465