Circulating Breast Tumor Cells Exhibit Dynamic Changes in Epithelial and Mesenchymal Composition

Massachusetts General Hospital Cancer Center, Harvard Medical School, Charlestown, MA 02129, USA.
Science (Impact Factor: 33.61). 02/2013; 339(6119):580-584. DOI: 10.1126/science.1228522
Source: PubMed

ABSTRACT Epithelial-mesenchymal transition (EMT) of adherent epithelial cells to a migratory mesenchymal state has been implicated
in tumor metastasis in preclinical models. To investigate its role in human cancer, we characterized EMT in circulating tumor
cells (CTCs) from breast cancer patients. Rare primary tumor cells simultaneously expressed mesenchymal and epithelial markers,
but mesenchymal cells were highly enriched in CTCs. Serial CTC monitoring in 11 patients suggested an association of mesenchymal
CTCs with disease progression. In an index patient, reversible shifts between these cell fates accompanied each cycle of response
to therapy and disease progression. Mesenchymal CTCs occurred as both single cells and multicellular clusters, expressing
known EMT regulators, including transforming growth factor (TGF)–β pathway components and the FOXC1 transcription factor.
These data support a role for EMT in the blood-borne dissemination of human breast cancer.

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Available from: Shannon L Stott, Apr 15, 2014
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    • "The relevance of the CTC/EMT relationship and its role in determining metastatic outcomes in breast cancer is explored in a recent study by Yu et al., which highlights the dynamic relationship between EMT and CTC level and shows the association between cancer subtype, treatment response, and stage of disease. They reveal that EMT, and consequently mesenchymal CTCs, occur more prevalently in aggressive disease subtypes typically characterized as being highly pro-metastatic [44] [63]. The persistent increase in the total CTC numbers we observed in biopsied mice likely has a cumulative impact that favors the possibility of successful metastatic colonization (Figure 6). "
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    ABSTRACT: Introduction: Incisional biopsies, including the diagnostic core needle biopsy (CNB), routinely performed before surgical excision of breast cancer tumors are hypothesized to increase the risk of metastatic disease. In this study, we experimentally determined whether CNB of breast cancer tumors results in increased distant metastases and examine important resultant changes in the primary tumor and tumor microenvironment associated with this outcome. Method: To evaluate the effect of CNB on metastasis development, we implanted murine mammary 4T1 tumor cells in BALB/c mice and performed CNB on palpable tumors in half the mice. Subsequently, emulating the human scenario, all mice underwent complete tumor excision and were allowed to recover, with attendant metastasis development. Tumor growth, lung metastasis, circulating tumor cell (CTC) levels, variation in gene expression, composition of the tumor microenvironment, and changes in immunologic markers were compared in biopsied and non-biopsied mice. Results: Mice with biopsied tumors developed significantly more lung metastases compared to non-biopsied mice. Tumors from biopsied mice contained a higher frequency of myeloid-derived suppressor cells (MDSCs) accompanied by reduced CD4 + T cells, CD8 + T cells, and macrophages, suggesting biopsy-mediated development of an increasingly immunosuppressive tumor microenvironment. We also observed a CNB-dependent up-regulation in the expression of SOX4, Ezh2, and other key epithelial-mesenchymal transition (EMT) genes, as well as increased CTC levels among the biopsy group. Conclusion: CNB creates an immunosuppressive tumor microenvironment, increases EMT, and facilitates release of CTCs, all of which likely contribute to the observed increase in development of distant metastases.
    Neoplasia (New York, N.Y.) 11/2014; DOI:10.1016/j.neo.2014.09.004 · 4.25 Impact Factor
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    • "Consequently, mesenchymal-like CTC subpopulations are difficult to identify in the hematopoietic cell environment which is also of mesenchymal origin (Joosse & Pantel, 2013). Of note, single tumor cells found in the blood of breast cancer patients exhibit EMT-associated changes, while cell clusters appear to require a partial EMT so that these cells possess the migratory abilities of a mesenchymal cell but retain the cell–cell interaction profile of an epithelial cell (Yu et al, 2013). "
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    ABSTRACT: Cancer metastasis is the main cause of cancer-related death, and dissemination of tumor cells through the blood circulation is an important intermediate step that also exemplifies the switch from localized to systemic disease. Early detection and characterization of circulating tumor cells (CTCs) is therefore important as a general strategy to monitor and prevent the development of overt metastatic disease. Furthermore, sequential analysis of CTCs can provide clinically relevant information on the effectiveness and progression of systemic therapies (e.g., chemo-, hormonal, or targeted therapies with antibodies or small inhibitors). Although many advances have been made regarding the detection and molecular characterization of CTCs, several challenges still exist that limit the current use of this important diagnostic approach. In this review, we discuss the biology of tumor cell dissemination, technical advances, as well as the challenges and potential clinical implications of CTC detection and characterization.
    EMBO Molecular Medicine 11/2014; 7(1). DOI:10.15252/emmm.201303698 · 8.67 Impact Factor
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    • "The relevance of EMT, and by inference of stemness reprogramming, in human tumor development is not uncontroversial [30]. However, recent flow cytometry-based demonstrations of circulating tumor cells with epithelial, mesenchymal, or hybrid signatures, and associated metastasis-initiating capacities, constitute direct evidence for human cancer cell plasticity and its pathophysiological significance [21], [31]. Our multi-parametric single-cell analysis of ex vivo tumor cell suspensions extends this evidence to primary breast cancers and uncovers that mixed epithelial/mesenchymal and mesenchymal-like breast cancer cell phenotypes are more prevalent and presumably more complex than previously thought. "
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    ABSTRACT: The stimulatory NKG2D receptor on lymphocytes promotes tumor immune surveillance by targeting ligands selectively induced on cancer cells. Progressing tumors counteract by employing tactics to disable lymphocyte NKG2D. This negative dynamic is escalated as some human cancer cells co-opt expression of NKG2D, thereby complementing the presence of its ligands for autonomous stimulation of oncogenic signaling. Clinical association data imply relationships between cancer cell NKG2D and metastatic disease. Here we show that NKG2D promotes cancer cell plasticity by induction of phenotypic, molecular, and functional signatures diagnostic of the epithelial–mesenchymal transition, and of stem-like traits via induction of Sox9, a key transcriptional regulator of breast stem cell maintenance. These findings obtained with model breast tumor lines and xenotransplants were recapitulated by ex vivo cancer cells from primary invasive breast carcinomas. Thus, NKG2D may have the capacity to drive high malignancy traits underlying metastatic disease.
    PLoS ONE 10/2014; 9(10):e108942. DOI:10.1371/journal.pone.0108942 · 3.23 Impact Factor
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