The Detection and Morphological Analysis of Circulating Tumor and Host Cells in Breast Cancer Xenograft Models

Abstract

Hematogenous dissemination may occur early in breast cancer (BC). Experimental models could clarify mechanisms, but in their development, the heterogeneity of this neoplasia must be considered. Here, we describe circulating tumor cells (CTCs) and the metastatic behavior of several BC cell lines in xenografts. MDA-MB-231, BT-474, MDA-MB-453 and MDA-MB-468 cells were injected at the orthotopic level in immunocompromised mice. CTCs were isolated using a size-based method and identified by cytomorphological criteria. Metastases were detected by COX IV immunohistochemistry. CTCs were detected in 90% of animals in each model. In MDA-MB-231, CTCs were observed after 5 weeks from the injection and step wisely increased at later time points. In animals injected with less aggressive cell lines, the load of single CTCs (mean ± SD CTCs/mL: 1.8 ± 1.3 in BT-474, 122.2 ± 278.5 in MDA-MB-453, 3.4 ± 2.5 in MDA-MB468) and the frequency of CTC clusters (overall 38%) were lower compared to MDA-MB231 (946.9 ± 2882.1; 73%). All models had lung metastases, MDA-MB-453 and MDA-MB468 had ovarian foci too, whereas lymph nodal involvement was observed in MDA-MB231 and MDA-MB-468 only. Interestingly, CTCs showed morphological heterogeneity and were rarely associated to host cells. Orthotopic xenograft of BC cell lines offers valid models of hematogenous dissemination and a possible experimental setting to study CTC-blood microenvironment interactions.

Dual Targeting of Cancer Cells with DARPin-Based Toxins for Overcoming Tumor Escape

“…The effectiveness of the developed targeted agents for solid tumors as well as metastasis treatment was evaluated using mouse model with xenograft tumors derived from BT-474 cell line. It was recently shown that ductal carcinoma cell line BT-474 has a great potential as cancer model with spontaneous metastasis [ 40 , 41 , 42 , 43 ]. It was shown BT-474-based tumors can form metastases in lymph nodes, lungs or spleen with various frequencies.…”

Liquid biopsies: Potential and challenges

“…Besides descriptive approaches, functional CTC assays exist (eg, the EPithelial ImmunoSPOT [EPISPOT] that is based on the measurement of secreted protein by viable CTCs after short‐term culture) 23 . In patients with extremely high CTC counts (usually >100 per mL blood), the functional properties of CTCs can be further investigated by the establishment of long‐term cell culture/cell lines or the development of xenograft models 24,25 (Figure 1A). However, the establishment of these models requires many months and the efficacy rates are very low, which makes them unsuitable as tool for clinical trials or decision‐making in individual patients.…”

Effects of Lidocaine and Src Inhibition on Metastasis in a Murine Model of Breast Cancer Surgery

“…This is technically very difficult however, as CTCs released as the primary tumour is manipulated would reach peripheral targets very rapidly and be removed from the circulation. A study examining CTCs in a murine breast cancer model found that there were only between 1 and 7 CTCs remaining per mL of blood 1 hour following an intravenous injection of 10 6 or 2 × 10 6 MDA-MB-231 cells in the lateral tail vein of the mice [34]. Such a rapid removal of cells from the circulation makes the timing of surgical excision and subsequent blood sampling (requiring cardiac puncture and sacrifice of the animal) to ensure capture of an adequate number of CTCs for Src evaluation extremely challenging.…”