Circulating Tumor Cell Clusters are Oligoclonal Precursors of Breast Cancer Metastasis
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ABSTRACT: Clusters of circulating tumor cells (CTC-clusters) are present in the blood of patients with cancer but their contribution to metastasis is not well defined. Here, we first use mouse models to demonstrate that breast cancer cells injected intravascularly as clusters are more prone to survive and colonize the lungs than single cells. Primary mammary tumors comprised of tagged cells give rise to oligoclonal CTC-clusters, with 50-fold increased metastatic potential, compared with single CTCs. Using intravital imaging and in vivo flow cytometry, CTC-clusters are visualized in the tumor circulation, and they demonstrate rapid clearance in peripheral vessels. In patients with breast cancer, presence of CTC-clusters is correlated with decreased progression-free survival. RNA sequencing identifies the cell junction protein plakoglobin as most differentially expressed between clusters and single human breast CTCs. Expression of plakoglobin is required for efficient CTC-cluster formation and breast cancer metastasis in mice, while its expression is associated with diminished metastasis-free survival in breast cancer patients. Together, these observations suggest that plakoglobin-enriched primary tumor cells break off into the vasculature as CTC-clusters, with greatly enhanced metastasis propensity. RNA-seq from 29 samples (15 pools of single CTCs and 14 CTC-clusters) isolated from 10 breast cancer patients
Project description:Cancer cells metastasize through the bloodstream either as single migratory circulating tumor cells (CTCs) or as multicellular groupings (CTC-clusters). Existing technologies for CTC enrichment are designed primarily to isolate single CTCs, and while CTC-clusters are detectable in some cases, their true prevalence and significance remain to be determined. Here, we developed a microchip technology (Cluster-Chip) specifically designed to capture CTC-clusters independent of tumor-specific markers from unprocessed blood. CTC-clusters are isolated through specialized bifurcating traps under low shear-stress conditions that preserve their integrity and even two-cell clusters are captured efficiently. Highly parallel architecture of the chip allows deterministic screening of clinically relevant volumes of blood samples at slow, and hence, non-damaging flow rates. Using the Cluster-Chip, we identify CTC-clusters in 30-40% of patients with metastatic cancers of the breast, prostate and melanoma. RNA sequencing of CTC-clusters confirms their tumor origin and identifies leukocytes within the clusters as being tissue-derived macrophages. Together, the development of a device for efficient capture of CTC-clusters will enable detailed characterization of their biological properties and role in cancer metastasis. We used the Cluster-Chip to capture CTC-clusters from the blood of a breast cancer patient with high CTC counts, released CTC-clusters in solution, stained them with TexasRed-conjugated antibodies against the leukocyte cell surface markers CD45, CD14 and CD16, and then isolated intact CTC-clusters individually using a micromanipulator. From a single time point, we retrieved 15 CTC-clusters, and each of those clusters was individually subjected to RNA-sequencing analysis using a next generation platform (SOLiD 5500). In addition, two leukocytes were isolated from the blood of a healthy donor were individually subjected to RNA-sequencing analysis using the same platform.
Project description:Analyses of circulating tumor cells (CTC) cultured from blood of patients with cancer may allow individualized testing for susceptibility to therapeutic regimens. We established ex vivo cultures of CTCs from six patients with metastatic estrogen receptor-positive breast cancer and performed RNA-Seq on those cultures. One sample each from six metastatic estrogen receptor positive breast cancer patients
Project description:Circulating Tumor Cells (CTCs) are shed from primary tumors into the bloodstream, mediating the hematogenous spread of cancer to distant organs. To determine the relevance of ECM protein expression to human disease, CTCs were isolated from the blood of metastatic PDAC patients and subjected to single cell RNA-sequencing. Analysis of 7 pancreatic CTCs from 3 patients revealed that the majority expressed keratins defining their epithelial origin. A total of 13 of 60 extracellular protein genes enriched in mouse CTCs (see GEO GSE51372) were expressed at high levels (>100 rpm) in at least one human pancreatic CTC. Human SPARC was the only gene found at high levels in all human pancreatic CTCs. To achieve a deep RNA sequencing profile of CTCs at the single cell level, we applied a novel inertial focusing-enhanced device, the CTC-iChip, which allows high efficiency negative depletion of normal blood cells, leaving unattached CTCs in solution where they can be selected and analyzed as single cells (Pubmed ID 23552373). CTCs were then subjected to single cell RNA-sequencing (Pubmed ID 20203668).
Project description:Clusters of circulating tumor cells (CTC-clusters) are present in the blood of patients with cancer but their contribution to metastasis is not well defined. Here, we first use mouse models to demonstrate that breast cancer cells injected intravascularly as clusters are more prone to survive and colonize the lungs than single cells. Primary mammary tumors comprised of tagged cells give rise to oligoclonal CTC-clusters, with 50-fold increased metastatic potential, compared with single CTCs. Using intravital imaging and in vivo flow cytometry, CTC-clusters are visualized in the tumor circulation, and they demonstrate rapid clearance in peripheral vessels. In patients with breast cancer, presence of CTC-clusters is correlated with decreased progression-free survival. RNA sequencing identifies the cell junction protein plakoglobin as most differentially expressed between clusters and single human breast CTCs. Expression of plakoglobin is required for efficient CTC-cluster formation and breast cancer metastasis in mice, while its expression is associated with diminished metastasis-free survival in breast cancer patients. Together, these observations suggest that plakoglobin-enriched primary tumor cells break off into the vasculature as CTC-clusters, with greatly enhanced metastasis propensity.
Project description:In many patients with solid tumors circulating tumor cells (CTCs), that form metastases, can be identified in peripheral blood. Detection and characterization of CTCs in cancer patients provide a unique opportunity to predict patient survival, select and monitor the efficacy of treatment as well as to gain insights into the cascade of metastatic events. Here, we describe a novel approach to identify CTC-specific molecular markers. Using an integrated platform for immunomagnetic enrichment and immunofluorescent identification of CTCs, blood samples with large numbers of CTCs were identified from patients with colorectal, prostate and breast cancers. Despite enrichment, CTCs are still outnumbered by "nonspecifically" captured leukocytes. In order to determine gene expression profile for CTCs, "background" gene expression signature of white blood cells must be taken into account. To this end, following enrichment for CTCs, RNA was also extracted from the remaining CTC-depleted blood samples. The following samples were used to generate the global expression profiles for CTCs:<br><br> 1a) SAMPLE170711SUB735: CTC-enriched blood sample from a patient with breast cancer). 3700 CTCs were identified per 7.5 ml of peripheral blood in this patient.<br> 1b) SAMPLE170712SUB735: Corresponding CTC-depleted blood sample for the above patient with breast cancer.<br> 2a) SAMPLE170829SUB750: CTC-enriched blood sample from a patient with prostate cancer. 647 CTCs were identified per 7.5 ml of peripheral blood in this patient.<br> 2b) SAMPLE170830SUB750: Corresponding CTC-depleted blood sample for the above patient with prostate cancer.<br> 3a) SAMPLE170831SUB751: CTC-enriched sample from a patient with colorectal cancer. 180 CTCs were identified per 7.5 ml of peripheral blood in this patient.<br> 3b) SAMPLE170832SUB751: Corresponding CTC-depleted blood sample for the above patient with colorectal cancer.
Project description:Circulating tumor cells (CTCs) are critical in the development of distant organ tumor metastasis, and are associated with advanced cancer stage and poor patient outcome. Here, we present the first genome-wide nucleotide-level characterization of CTCs. Our single-nucleotide polymorphism (SNP) analysis in patients with melanoma involved: 1) global comparative genomic analysis of CTCs and matched regional metastases, 2) identification of key genomic aberrations in CTCs, 3) verification of these target genes in aggressive distant tumor metastases, and 4) evidence of selective expression and functional consequence of CTC-associated genes in melanomas. We report 131 aberrant loci in CTCs that are potentially pro-metastatic, and show that such expression of a 5-marker gene panel (CSMD2, CNTNAP5, FLJ14051, ADAM6, TRPM2) in melanomas confers prognostic utility. Successful treatment of melanoma requires understanding of the metastatic process and identification of patients with tumors most likely to develop aggressive metastatic disease. Melanomas are heterogeneous, and CTCs have long been recognized as vehicles for cancer spread, representing particularly aggressive tumor clones that can evolve into successful clinical metastases. Elucidation of genomic aberrations in CTCs will aid in the development of prognostic biomarkers and therapeutic strategies to target CTCs to prevent or control distant cancer spread. This study provides the first detailed genomic confirmation of the close relation between CTCs and tumor metastases, and illustrates how CTCs can be utilized as a novel approach and rational source for identification of pro-metastatic genes in cancer research. Three individual patient cohorts were utilized in the study. CNV and LOH loci were evaluated initially in metastatic melanoma patients (n=13) in a discovery cohort. SNP loci that harbored CNV/LOH in CTCs were then separately verified for: (a) presence in distant organ metastasis (AJCC Stage IV melanoma) (n=27), and (b) relevance to prognosis in regional melanoma metastasis (AJCC Stage III melanoma) (n=35). The first discovery patient cohort group was utilized for capture of CTCs, and consisted of peripheral blood mononuclear cell (PBMC) and tumor specimens from metastatic melanoma patients (n=13). CTC-related loci were verified in a second cohort of patients with Stage IV distant organ metastases (n=27), including 15 brain, 4 lung, and 8 gastrointestinal (bowel, liver) metastases. The third patient cohort consisted of early passage (<12) established melanoma cell lines derived from 35 regional melanoma metastases (Stage III) for evaluation of the prognostic utility of the CTC-associated aberrant loci.
Project description:We developed a method to isolate pure circulating tumor cells (CTC). RNA from such CTCs isolated from the peripheral blood of metastatic breast cancer patients and gene expression was performed using cDNAmicroarray. we used cDNA array to compare gene expression of CTCs with normal epithelial and breast tumor samples normal blood vs. breast tumor
Project description:The ability of circulating tumor cells (CTCs) to form clusters has been linked to increased metastatic potential. Yet biological features and vulnerabilities of CTC clusters remain largely unknown. Our DNA methylation analysis led us to hypothesize that CTC clusters are characterized by active TF networks that support both stemness and proliferation. To identify whether the stemness- and proliferation-related TF networks are also transcriptionally active in CTC clusters compared to single CTCs, we performed single-cell resolution RNA sequencing analysis of single CTCs and CTC clusters, matched within individual liquid biopsies and isolated from six breast cancer patients with progressive metastatic disease, and of single CTCs and CTC clusters isolated from three xenograft models. In addition, among 2,486 FDA-approved compounds, we identify Na+/K+ ATPase inhibitors that enable the dissociation of CTC clusters into single cells, leading to DNA methylation remodeling at critical sites and metastasis suppression. We performed RNA sequencing analysis of BR16 and Brx50 cells upon treatment to assess the molecular consequences of clusters dissociation.
Project description:The presence of circulating tumor cell (CTC) clusters is associated with disease progression, new metastasis formation and reduced survival in a variety of cancer types. In breast cancer, pre-clinical studies showed that inhibitors of the Na+/K+-ATPase can suppress CTC clusters shedding and block metastasis. Here, we conducted a prospective, open-label, phase I study in patients with metastatic breast cancer, where the primary endpoint was to determine whether a short (one week) treatment with the Na+/K+-ATPase inhibitor digoxin could reduce mean CTC cluster size. Mechanistically, transcriptome profiling of CTCs highlighted downregulation of cell-cell adhesion and cell cycle-related genes upon treatment with digoxin, in line with its cluster-dissolution activity. ClinicalTrials.gov identifier: NCT03928210.
Project description:We developed a method to isolate pure circulating tumor cells (CTC). RNA from such CTCs isolated from the peripheral blood of metastatic breats cnacer patients and gene expression was performed using cDNAmicroarray. we used cDNA array to compare gene expression of CTCs with normal epithelial and breast tumor samples CTCs vs. breast tumors