Marker Epithelial Cell Adhesion Molecule Research Articles

Potent and selective eradication of tumor cells by an EpCAM-targeted Ras-degrading enzyme

Despite decades of efforts, an urgent need remains to develop tumor cell-selective rat sarcoma (Ras)-targeting therapies that can treat patients with Ras-driven tumors. Here we report modular engineered proteins that degrade Ras selectively in tumor cells that overexpress the tumor cell marker epithelial cell adhesion molecule (EpCAM) by fusing the Ras degrader Ras-Rap1-specific endopeptidase with the translocation domain of the Pseudomonas aeruginosa exotoxin A (ETA) or diphtheria toxin (DT). Redirection to EpCAM is achieved by a designed ankyrin repeat protein. In two-dimensional tumor cell cultures, complete degradation of Ras proteins after 24h was observed with EpCAM-targeted Ras degraders fused to ETA or DT in EpCAM-overexpressing MCF7 and HCT116 cells, with median inhibition concentration values at sub-nanomolar levels. The viability of EpCAM-low non-cancerous fibroblasts remained unaffected. In a three-dimensional (3D) tumor-on-a-chip system that mimics the natural tumor microenvironment, effective Ras degradation and selective toxicity toward tumor cells, particularly with the ETA-fused constructs, was determined on-chip. To conclude, we demonstrate the potential of modular engineered proteins to kill tumor cells highly selectively by simultaneously exploiting EpCAM as a tumor-specific cell surface molecule as well as Ras as an intracellular oncotarget in a 3D system mimicking the natural tumor microenvironment.

Tumour stemness and poor clinical outcomes in haemochromatosis patients with hepatocellular carcinoma

AimsPatients with haemochromatosis (HFE) are known to have an increased risk of developing hepatocellular carcinoma (HCC). Available data are conflicting on whether such patients have poorer prognosis, and there is...

Cellular, Molecular and Proteomic Characteristics of Early Hepatocellular Carcinoma.

Hepatocellular carcinoma (HCC) accounts for the majority of primary liver cancers. Early detection/diagnosis is vital for the prognosis of HCC, whereas diagnosis at late stages is associated with very low survival rate. Early diagnosis is based on 6-month surveillance of the patient and the use of at least two imaging modalities. The aim of this study was to investigate diagnostic markers for the detection of early HCC based on proteome analysis, microRNAs (miRNAs) and circulating tumor cells (CTCs) in the blood of patients with cirrhosis or early or advanced HCC. We studied 89 patients with HCC, of whom 33 had early HCC and 28 were cirrhotic. CTCs were detected by real-time quantitative reverse transcription PCR and immunofluorescence using the markers epithelial cell adhesion molecule (EPCAM), vimentin, alpha fetoprotein (aFP) and surface major vault protein (sMVP). Expression of the five most common HCC-involved miRNAs (miR-122, miR-200a, miR-200b, miR-221, miR-222) was examined in serum using quantitative real time PCR (qRT-PCR). Finally, patient serum was analyzed via whole proteome analysis (LC/MS). Of 53 patients with advanced HCC, 27 (51%) had detectable CTCs. Among these, 10/27 (37%) presented evidence of mesenchymal or intermediate stage cells (vimentin and/or sMVP positive). Moreover, 5/17 (29%) patients with early HCC and 2/28 (7%) cirrhotic patients had detectable CTCs. Patients with early or advanced HCC exhibited a significant increase in miR-200b when compared to cirrhotic patients. Our proteome analysis indicated that early HCC patients present a significant upregulation of APOA2, APOC3 proteins when compared to cirrhotic patients. When taken in combination, this covers the 100% of the patients with early HCC. miR-200b, APOA2 and APOC3 proteins are sensitive markers and can be potentially useful in combination for the early diagnosis of HCC.

High expression of both desmoplastic stroma and epithelial to mesenchymal transition markers associate with shorter survival in pancreatic ductal adenocarcinoma.

Desmoplastic stroma (DS) and the epithelial-to-mesenchymal transition (EMT) play a key role in pancreatic ductal adenocarcinoma (PDAC) progression. To date, however, the combined expression of DS and EMT markers, and their association with variations in survival within each clinical stage and degree of tumor differentiation is unknown. The purpose of this study was to investigate the association between expression of DS and EMT markers and survival variability in patients diagnosed with PDAC. We examined the expression levels of DS markers alpha smooth muscle actin (α-SMA), fibronectin, and vimentin, and the EMT markers epithelial cell adhesion molecule (EPCAM), pan-cytokeratin, and vimentin, by immunohistochemistry using a tissue microarray in a retrospective cohort of 25 patients with PDAC. The results were examined for association with survival by clinical stage and by degree of tumor differentiation. High expression of DS markers -α-SMA, fibronectin, and vimentin- was associated with decreased survival at intermediate and advanced clinical stages (p=0.006-0.03), as well as with both poorly and moderately differentiated tumor grades (p=0.01-0.02). Interestingly, the same pattern was observed for EMT markers, i.e., EPCAM, pan-cytokeratin, and vimentin (p=0.00008-0.03). High expression of DS and EMT markers within each clinical stage and degree of tumor differentiation was associated with lower PDAC survival. Evaluation of these markers may have a prognostic impact on survival time variation in patients with PDAC.

A Review of Circulating Tumour Cell Enrichment Technologies.

Simple SummaryCirculating tumour cells (CTCs) are cancer cells shed into the bloodstream from tumours and their analysis can provide important insights into cancer detection and monitoring, with the potential to direct personalised therapies for the patient. These CTCs are rare in the blood, which makes their detection and enrichment challenging and to date, only one technology (the CellSearch) has gained FDA approval for determining the prognosis of patients with advanced breast, prostate and colorectal cancers. Here, we review the wide range of enrichment technologies available to isolate CTCs from other blood components and highlight the important characteristics that new technologies should possess for routine clinical use.Circulating tumour cells (CTCs) are the precursor cells for the formation of metastatic disease. With a simple blood draw, liquid biopsies enable the non-invasive sampling of CTCs from the blood, which have the potential to provide important insights into cancer detection and monitoring. Since gaining FDA approval in 2004, the CellSearch system has been used to determine the prognosis of patients with metastatic breast, prostate and colorectal cancers. This utilises the cell surface marker Epithelial Cell Adhesion Molecule (EpCAM), to enrich CTCs, and many other technologies have adopted this approach. More recently, the role of mesenchymal-like CTCs in metastasis formation has come to light. It has been suggested that these cells are more aggressive metastatic precursors than their epithelial counterparts; however, mesenchymal CTCs remain undetected by EpCAM-based enrichment methods. This has prompted the development of a variety of ‘label free’ enrichment technologies, which exploit the unique physical properties of CTCs (such as size and deformability) compared to other blood components. Here, we review a wide range of both immunocapture and label free CTC enrichment technologies, summarising the most significant advantages and disadvantages of each. We also highlight the important characteristics that technologies should possess for routine clinical use, since future developments could have important clinical implications, with the potential to direct personalised therapies for patients with cancer.

Integrated system for detection and molecular characterization of circulating tumor cells.

Circulating tumor cells (CTCs) invade blood vessels in solid tumors and promote metastases by circulating in the blood. CTCs are thus recognized as targets for liquid biopsy and can provide useful information for design of treatments. This diagnostic approach must consider not only the number of CTCs but also their molecular and genetic characteristics. For this purpose, use of devices that enrich CTCs independent of these characteristics and detectors that recognize various CTC characteristics is essential. In the present study, we developed a CTC detection system comprising ClearCell FX and ImageStream Mark II. We clarified the analytical performance of this system by evaluating recovery rate, lower limits of detection, and linearity. These parameters are critical for detecting rare cells, such as CTCs. We tested these parameters using three cell lines with different expression levels of the epithelial marker-epithelial cell adhesion molecule (EpCAM) and spiked these cells into whole-blood samples from healthy donors. The average recovery rate and lower limit of detection were approximately 40% and five cells/7.5 mL of whole blood, respectively. High linearity was observed for all evaluated samples. We also evaluated the ability of the system to distinguish between normal and abnormal cells based on protein expression levels and gene amplification and found that the system can identify abnormal cells using these characteristics. The CTC detection system thus displays the ability to distinguish specific characteristics of CTC, thereby providing valuable information for cancer treatment.

Matrine suppresses stemness of hepatocellular carcinoma cells by regulating β-catenin signaling pathway

To explore the effects of matrine on the proliferation, tumor cell stemness, β-catenin transcriptional activity and AKT/GSK3β/β-catenin signaling pathway in human hepatocellular carcinoma (HCC) HepG2 and Huh7 cells. The proliferation and colony formation ability of HepG2 and Huh7 cells treated with 200, 400, and 800 μg/mL matrine were evaluated with MTT assay and colony formation assay, respectively. Real-time quantitative PCR was performed to detect the mRNA expressions of CD90, epithelial cell adhesion molecule (EpCAM) and CD133, and dual-luciferase assay was used to detect the transcriptional activity of β-catenin in the treated cells. The effects of matrine on the expressions of protein kinase B (AKT), P-AKT, GSK-3β, P-GSK-3β, P-β-catenin and β-catenin proteins in the Wnt/β-catenin signaling pathway were assessed using Western blotting. Matrine inhibited the proliferation of the two HCC cell lines in a time- and concentration-dependent manner. The half-inhibitory concentrations of matrine were 2369, 1565 and 909.1 μg/mL at 24, 48 and 72 h in HepG2 cells, respectively, and were 1355, 781.8, and 612.8 μg/mL in Huh7 cells, respectively. Matrine concentrationdependently suppressed colony formation of the HCC cells, producing significant inhibitory effects at 400 μg/mL P < 0.01) and 800 μg/mL P < 0.001) in HepG2 cells and at 200 μg/mL P < 0.05), 400 μg/mL P < 0.01), and 800 μg/mL P < 0.001) in Huh7 cells. Matrine at 400 and 800 μg/mL significantly inhibited the mRNA expression of CD90, EpCAM and CD133 and the transcriptional level of β-catenin in both HepG2 and Huh7 cells P < 0.05 or 0.01). Matrine at 400 and 800 μg/mL also significantly decreased the protein levels of β-catenin, P-AKT and P-GSK-3β and increased the phosphorylation level of β-catenin in both of the cell lines. Matrine inhibits the proliferation, colony formation, and the expressions of tumor stem cell markers CD90, EpCAM and CD133 in both HepG2 and Huh7 cells probably by inhibiting Wnt/β-catenin signaling pathway and the transcriptional activity ofβ-catenin.

Influence of size and charge of unstructured polypeptides on pharmacokinetics and biodistribution of targeted fusion proteins

Alternative non-IgG binding proteins developed for therapy are small in size and, thus, are rapidly cleared from the circulation by renal filtration. To avoid repeated injection or continuous infusion for the maintenance of therapeutic serum concentrations, extensions of unfolded polypeptides have been developed to prolong serum half-life, but systematic, comparative studies investigating the influence of their size and charge on serum half-life, extravasation, tumor localization and excretion mechanisms have so far been lacking. Here we used a high-affinity Designed Ankyrin Repeat Protein (DARPin) targeting the tumor marker epithelial cell adhesion molecule (EpCAM) in a preclinical tumor xenograft model in mice, and fused it with a series of defined unstructured polypeptides. We used three different sizes of two previously described polypeptides, an uncharged one consisting of only Pro, Ala and Ser (termed PAS) and a charged one consisting of Pro, Ala, Ser, Thr, Gly, Glu (termed XTEN) and performed for the first time a precise comparative localization, distribution and extravasation study. Pharmacokinetic analysis showed a clear linear relationship between hydrodynamic radius and serum half-life across both polypeptides, reaching a half-life of up to 21 h in mice. Tumor uptake was EpCAM-dependent and directly proportional to half-life and size, showing an even tumor penetration for all fusion proteins without unspecific accumulation in non-target tissue. Unexpectedly, charge had no influence on any parameter, neither tumor nor tissue accumulation nor kidney elimination kinetics. Thus, both polypeptide types have a very similar potential for precise half-life modification and tumor targeting.

Clinical outcome of hepatocellular carcinoma can be predicted by the expression of hepatic progenitor cell markers and serum tumour markers.

The high heterogeneity of hepatocellular carcinomas (HCCs) complicates stratification of HCC patients for treatment. Therefore, it is necessary to establish a comprehensive panel of HCC biomarkers related to tumour behaviour and cancer prognosis. Resected HCCs from 251 patients were stained for hepatic progenitor cell (HPC) markers epithelial cell adhesion molecule (EpCAM), neural cell adhesion molecule (NCAM), delta-like 1 homolog (DLK1), and cytokeratin 19 (CK19). Staining patterns were analysed for their prognostic association with relapse-free survival and overall survival. α-Fetoprotein (AFP), lectin-reactive α-fetoprotein (AFP-L3), and des-γ-carboxy prothrombin (DCP) were assessed as indicators of HPC protein expression. Expression pattern of HPC markers correlated with tumour malignancy indicated by high AFP/AFP-L3 serum levels, more frequent vascular invasion, and poorer tumour differentiation. EpCAM expression, DCP ≥300 mAU/ml, age ≥60, and Child-Pugh score grade B or C were independent prognostic factors of poor outcome and were used in a new scoring system for HCC prognosis after operation. Expression of two or more HPC markers was a significant predictor of poor HCC outcome and serum levels of AFP/AFP-L3 correlated with the expression of HPC proteins. Our study paved the way for further elucidation of the association among HPC markers, serum tumour markers, and HCC clinical outcome for precision medicine.

Characterization of Urothelial Cancer Circulating Tumor Cells with a Novel Selection-Free Method

To investigate circulating tumor cells (CTCs) as biomarkers of urothelial carcinoma (UC). To date, the majority of work on this topic has utilized the CellSearch test, which has limited sensitivity due to reliance on positive selection for the cell surface protein epithelial cell adhesion molecule (EpCAM). We used a novel selection-free method to enumerate and characterize CTCs across a range of UC stages. Blood samples from 38 patients (9 controls, 8 nonmuscle invasive bladder cancer [NMIBC], 12 muscle-invasive bladder cancer [MIBC], and 9 metastatic UC) were processed with the AccuCyte-CyteFinder system. Slides were stained for the white blood cell markers CD45 and CD66b and the epithelial markers EpCAM and pancytokeratin. CTCs were defined as any cytokeratin postive and white blood cell marker negative cell. Separately, the more restrictive CellSearch definition was applied, with the additional requirement of EpCAM positivity. The Kruskal-Wallis ANOVA test compared CTC counts by stage. Greater than or equal to 1 CTC was detected in 2 of 8 (25%) patients with NMIBC, 7 of 12 (58%) with MIBC, and 6of 9 (67%) with metastatic disease. No control had CTCs. Comparing CTC counts between groups, the only statistically significant comparison was between controls and patients with metastatic UC (P = .009). With EpCAM positivity as a CTC requirement, no CTCs were detected in any patient with NMIBC, and only 2 (17%) patients with MIBC had CTCs. CTCs tended to be larger in metastatic patients. CTCs were detected at all UC stages and exhibited phenotypic diversity of cell size and EpCAM expression. EpCAM negative CTCs that would be missed with the CellSearch test were detected in patients with NMIBC and patients with MIBC.

Mesenchymal stem cells rescue acute hepatic failure by polarizing M2 macrophages

AIMTo investigate whether M1 or M2 polarization contributes to the therapeutic effects of mesenchymal stem cells (MSCs) in acute hepatic failure (AHF).METHODSMSCs were transfused into rats with AHF induced by D-galactosamine (DGalN). The therapeutic effects of MSCs were evaluated based on survival rate and hepatocyte proliferation and apoptosis. Hepatocyte regeneration capacity was evaluated by the expression of the hepatic progenitor surface marker epithelial cell adhesion molecule (EpCAM). Macrophage polarization was analyzed by M1 markers [CD68, tumor necrosis factor alpha (TNF-α), interferon-γ (IFN-γ), inducible nitric oxide synthase (INOS)] and M2 markers [CD163, interleukin (IL)-4, IL-10, arginase-1 (Arg-1)] in the survival and death groups after MSC transplantation.RESULTSThe survival rate in the MSC-treated group was increased compared with the DPBS-treated control group (37.5% vs 10%). MSC treatment protected rats with AHF by reducing apoptotic hepatocytes and promoting hepatocyte regeneration. Immunohistochemical analysis showed that MSC treatment significantly increased the expression of EpCAM compared with the control groups (P < 0.001). Expression of EpCAM in the survival group was significantly up-regulated compared with the death group after MSC transplantation (P = 0.003). Transplantation of MSCs significantly improved the expression of CD163 and increased the gene expression of IL-10 and Arg-1 in the survival group. IL-4 concentrations were significantly increased compared to the death group after MSC transplantation (88.51 ± 24.51 pg/mL vs 34.61 ± 6.6 pg/mL, P < 0.001). In contrast, macrophages showed strong expression of CD68, TNF-α, and INOS in the death group. The concentration of IFN-γ was significantly increased compared to the survival group after MSC transplantation (542.11 ± 51.59 pg/mL vs 104.07 ± 42.80 pg/mL, P < 0.001).CONCLUSIONM2 polarization contributes to the therapeutic effects of MSCs in AHF by altering levels of anti-inflammatory and pro-inflammatory factors.

Discrete microfluidics for the isolation of circulating tumor cell subpopulations targeting fibroblast activation protein alpha and epithelial cell adhesion molecule

Circulating tumor cells consist of phenotypically distinct subpopulations that originate from the tumor microenvironment. We report a circulating tumor cell dual selection assay that uses discrete microfluidics to select circulating tumor cell subpopulations from a single blood sample; circulating tumor cells expressing the established marker epithelial cell adhesion molecule and a new marker, fibroblast activation protein alpha, were evaluated. Both circulating tumor cell subpopulations were detected in metastatic ovarian, colorectal, prostate, breast, and pancreatic cancer patients and 90% of the isolated circulating tumor cells did not co-express both antigens. Clinical sensitivities of 100% showed substantial improvement compared to epithelial cell adhesion molecule selection alone. Owing to high purity (>80%) of the selected circulating tumor cells, molecular analysis of both circulating tumor cell subpopulations was carried out in bulk, including next generation sequencing, mutation analysis, and gene expression. Results suggested fibroblast activation protein alpha and epithelial cell adhesion molecule circulating tumor cells are distinct subpopulations and the use of these in concert can provide information needed to navigate through cancer disease management challenges.

De Novo Emergence of Mesenchymal Stem-Like CD105+ Cancer Cells by Cytotoxic Agents in Human Hepatocellular Carcinoma

BACKGROUND: Cancer stem cells (CSCs) are considered a pivotal target for the eradication of hepatocellular carcinoma (HCC). Recently, we reported that the CSC markers epithelial cell adhesion molecule (EpCAM) and CD90 are expressed independently in primary HCCs and cell lines, and CD90+ cells share features of metastatic vascular endothelial cells and express the vascular endothelial marker CD105, a co-receptor of transforming growth factor-beta. METHODS: The EpCAM+ cell lines HuH1 and HuH7 were treated with 5-fluorouracil (5-FU) or epirubicin in vitro. Gene and protein expression levels were evaluated by quantitative reverse transcription-polymerase chain reaction (qRT-PCR) and fluorescence-activated cell sorting, respectively. The expression of CD105 in primary HCC was evaluated by immunohistochemistry. The relationship of CD105 expression status and HCC prognosis was evaluated using 85 surgically resected HCC tissues by Kaplan–Meier survival analysis. RESULTS: 5-FU or epirubicin treatment resulted in the generation of CD90+ and CD105+ cells in vitro in HuH1 and HuH7 cells, which originally contain no CD90+ or CD105+ cells. This phenomenon was validated by qRT-PCR analysis with activation of the epithelial-mesenchymal transition (EMT) program regulators Snail family zinc finger 1 (SNAI1) and SNAI2. Immunohistochemical analysis indicated that CD105+ cells were morphologically identical to vascular endothelial cells in untreated primary HCCs. However, surgically resected specimens after transcatheter arterial chemoembolization clearly indicated that CD105+ cancer cells survived at the peripheral edge of the tumor. Kaplan–Meier survival analysis indicated that HCCs expressing CD105 showed poor prognosis after surgery with statistical significance. CONCLUSIONS: Taken together, our data highlight the role of CD105+ HCC cells with activation of the EMT program generated de novo after cytotoxic therapy on the prognosis of HCC patients.

Abstract P2-02-13: EpCAM-independent enrichment approach for isolation of circulating tumor cells (CTCs) in breast cancer - What can be found in the EpCAM-depleted fraction?

Abstract Circulating tumor cells (CTCs) are the potential precursors of metastatic disease. Many assays have been established for the enumeration of CTCs. However, major limitations include the reliance on the expression of the cell surface marker epithelial cell adhesion molecule (EpCAM). These approaches may not detect CTCs that either express no/low levels of EpCAM or undergo epithelial-to-mesenchymal transition (EMT). We present an enrichment strategy combining different antibodies specific for surface proteins and extracellular matrix (ECM) components to capture EpCAMneg cell lines and EpCAMneg CTCs from EpCAM-depleted breast cancer blood samples. Expression of proteins (Trop2, CD49f, cMet, CK8, CD44, ADAM8, CD146, TEM8, CD47) was verified by immunofluorescence on EpCAM-positive (e.g. MCF7, SKBR3) and -negative (MDA-MB-231) breast cancer cell lines; antibodies and ECM proteins (e.g. hyaluronic acid (HA), collagen I, laminin) were further spotted in a single- and multi-arrayed format onto glass slides (Schott, NEXTERION® AL) and coupled to immunomagnetic beads (Dynabeads/Adembeads). Tumor cell adhesion of EpCAMpos/neg cell lines was visualized by Coomassie/MitoTracker; EpCAMneg CTCs enriched via functionalized Adem-/Dynabeads were identified by immunofluorescence staining for anti-pan-Cytokeratin(CK)-FITC/anti-CD45 AF647/DAPI and quantified manually by microscopy. Regarding cell lines, marginal binding of EpCAMneg MDA-MB-231 cells to EpCAM-antibodies could be observed. Efficient adhesion/capturing of EpCAMneg cells could be achieved via HA and immobilized antibodies against CD49f and Trop2. By analyzing 29 EpCAM-depleted fractions from 25 metastatic breast cancer patients, we were able to identify EpCAMneg CTCs in 69% of the samples [range 1-24] applying Trop2, CD49f, cMet, CK8 and/or HA magnetic enrichment. Accessorily, EpCAMneg dual-positive (CKpos/CD45pos) cells could be traced in 28 out of 29 samples [range 1-480]. Herein, we demonstrate an enhanced enrichment strategy to optimize capturing of EpCAMneg CTCs by targeting various cell surface antigens with antibody mixtures and ECM components. Thereby, potential relevant CTCs can be gathered and subjected to subsequent molecular analysis. Citation Format: Fehm T, Schneck H, Gierke B, Pawlak M, Templin M, Niederacher D, Neubauer H. EpCAM-independent enrichment approach for isolation of circulating tumor cells (CTCs) in breast cancer - What can be found in the EpCAM-depleted fraction?. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P2-02-13.

EpCAM-Independent Enrichment of Circulating Tumor Cells in Metastatic Breast Cancer.

Circulating tumor cells (CTCs) are the potential precursors of metastatic disease. Most assays established for the enumeration of CTCs so far–including the gold standard CellSearch—rely on the expression of the cell surface marker epithelial cell adhesion molecule (EpCAM). But, these approaches may not detect CTCs that express no/low levels of EpCAM, e.g. by undergoing epithelial-to-mesenchymal transition (EMT). Here we present an enrichment strategy combining different antibodies specific for surface proteins and extracellular matrix (ECM) components to capture an EpCAMlow/neg cell line and EpCAMneg CTCs from blood samples of breast cancer patients depleted for EpCAM-positive cells. The expression of respective proteins (Trop2, CD49f, c-Met, CK8, CD44, ADAM8, CD146, TEM8, CD47) was verified by immunofluorescence on EpCAMpos (e.g. MCF7, SKBR3) and EpCAMlow/neg (MDA-MB-231) breast cancer cell lines. To test antibodies and ECM proteins (e.g. hyaluronic acid (HA), collagen I, laminin) for capturing EpCAMneg cells, the capture molecules were first spotted in a single- and multi-array format onto aldehyde-coated glass slides. Tumor cell adhesion of EpCAMpos/neg cell lines was then determined and visualized by Coomassie/MitoTracker staining. In consequence, marginal binding of EpCAMlow/neg MDA-MB-231 cells to EpCAM-antibodies could be observed. However, efficient adhesion/capturing of EpCAMlow/neg cells could be achieved via HA and immobilized antibodies against CD49f and Trop2. Optimal capture conditions were then applied to immunomagnetic beads to detect EpCAMneg CTCs from clinical samples. Captured CTCs were verified/quantified by immunofluorescence staining for anti-pan-Cytokeratin (CK)-FITC/anti-CD45 AF647/DAPI. In total, in 20 out of 29 EpCAM-depleted fractions (69%) from 25 metastatic breast cancer patients additional EpCAMneg CTCs could be identified [range of 1–24 CTCs per sample] applying Trop2, CD49f, c-Met, CK8 and/or HA magnetic enrichment. EpCAMneg dual-positive (CKpos/CD45pos) cells could be traced in 28 out of 29 samples [range 1–480]. By single-cell array-based comparative genomic hybridization we were able to demonstrate the malignant nature of one EpCAMneg subpopulation. In conclusion, we established a novel enhanced CTC enrichment strategy to capture EpCAMneg CTCs from clinical blood samples by targeting various cell surface antigens with antibody mixtures and ECM components.

EpCAM-independent enrichment approach for isolation of circulating tumor cells (CTCs) in breast cancer – What can be found in the EpCAM-depleted fraction?

CTCs are essential for establishing metastasis in breast cancer. While many assays currently exist for the enumeration of CTCs, limitations include the reliance on the expression of the cell surface marker epithelial cell adhesion molecule (EpCAM). These approaches may omit CTCs expressing either no/low levels of EpCAM, eventually representing the metastasis-initiating population. In order to successfully capture EpCAM-negative or -low breast cancer cells we have tested different antibodies specific for surface proteins and extracellular matrix (ECM) components for cell lines, spiked samples and blood of metastatic breast cancer patients.

Cancer stem cells in hepatocellular carcinoma--an immunohistochemical study with histopathological association.

Background & objectives:Cancer stem cells (CSCs) may be responsible for tumour recurrence and resistance to chemotherapy in hepatocellular carcinoma (HCC). This study was carried out to evaluate the association between histological parameters and liver CSCs (LCSC) in HCC, and to compare distribution of liver CSCs in HCC associated with and without hepatitis B virus (HBV) infection.Methods:Seventy nine tumours (49 surgical resections from 46 patients, and 30 from autopsy) were reviewed. Immunohistochemical staining for the LCSC marker EpCAM (epithelial cell adhesion molecule), liver progenitor cell (LPC) markers CK19 (cytokeratin 19) and neural cell adhesion molecule (NCAM) were performed and were associated with histological features of tumour behaviour.Results:Thirty three tumours (41.8%) showed positive staining for EpCAM. CK19 and NCAM expression were seen in 26 (32.9%) and four (5.1%) tumours, respectively. The expression of EpCAM and CK19 was significantly associated with each other (P<0.001). EpCAM expression was significantly associated with clinical and histological features indicating aggressive tumour behaviour, including younger age of onset, higher serum alpha foetoprotein (AFP) levels, tumour cell dedifferentiation, increased mitotic activity, and vascular invasiveness. There was no significant difference in expression of EpCAM, CK19 and NCAM between HBV positive and negative HCC.Interpretation & conclusions:The LCSC marker EpCAM was expressed in less than half of HCC, was independent of HBV aetiology, and was strongly associated with clinical and histological features of aggressive tumour behaviour. Positive staining for CK19 suggests a possible LPC origin of the EpCAM positive HCCs.

Immunohistochemical analysis of cancer stem cell markers in pancreatic adenocarcinoma patients after neoadjuvant chemoradiotherapy.

BackgroundCancer stem cells (CSCs) have been reported to play an important role in chemoradiation resistance. Although the association of CSC markers with clinicopathological outcomes after neoadjuvant chemoradiotherapy (NACRT) has been reported in various types of cancers, there have been no such reports for pancreatic cancer. Here we examined the sequential changes in CSC marker expressions after NACRT in patients with pancreatic adenocarcinoma (PA) and the impact of these changes on the prognosis.MethodsWe used immunohistochemistry to evaluate the expressions of the CSC markers epithelial cell adhesion molecule (EpCAM), CD24, CD44, CD133, CXCR4 and Aldehyde dehydrogenase 1 (ALDH1) in resected specimens obtained from 28 PA patients, and we compared these expressions with the patients’ clinicopathological parameters and survival data.ResultsThe expression frequencies of CD44 and ALDH1 were significantly higher in the NACRT group (n = 17) compared to the non-NACRT group (n = 11), but the CD133 expression was significantly lower in the NACRT group. In the NACRT group, the expression of CD133 was inversely correlated with that of ALDH1, and CD133+/ALDH1- expression was associated with an unfavorable patient outcome.ConclusionThis is the first report showing that NACRT may influence the expression frequencies of CD44, CD133 and ALDH1 in PA patients. Moreover, CD133 and ALDH1 expressions may be useful predictors of prognosis in PA patients who have received NACRT.Electronic supplementary materialThe online version of this article (doi:10.1186/1471-2407-14-687) contains supplementary material, which is available to authorized users.

A microchip filter device incorporating slit arrays and 3-D flow for detection of circulating tumor cells using CAV1-EpCAM conjugated microbeads

Circulating tumor cells (CTCs) are rare cells and the presence of these cells may indicate a poor prognosis and a high potential for metastasis. Despite highly promising clinical applications, CTCs have not been investigated thoroughly, due to many technical limitations faced in their isolation and identification. Current CTC detection techniques mostly take the epithelial marker epithelial cell adhesion molecule (EpCAM), however, accumulating evidence suggests that CTCs show heterogeneous EpCAM expression due to the epithelial-to-mesenchymal transition (EMT). In this study, we report that a microchip filter device incorporating slit arrays and 3-dimensional flow that can separate heterogeneous population of cells with marker for CTCs. To select target we cultured breast cancer cells under prolonged mammosphere culture conditions which induced EMT phenotype. Under these conditions, cells show upregulation of caveolin1 (CAV1) but down-regulation of EpCAM expression. The proposed device which contains CAV1-EpCAM conjugated bead has several tens of times increased throughput. More importantly, this platform enables the enhanced capture yield from metastatic breast cancer patients and obtained cells that expressed various EMT markers. Further understanding of these EMT-related phenotypes will lead to improved detection techniques and may provide an opportunity to develop therapeutic strategies for effective treatment and prevention of cancer metastasis.

Abstract P1-04-07: Isolation and expression profiling of EpCAM-negative circulating tumor cells in human and xenograft models of breast cancer

Abstract Background: While several assays currently exist to enumerate circulating tumor cells (CTCs), limitations to existing assays include reliance on the expression of the cell surface marker epithelial cell adhesion molecule (EpCAM) and difficulty isolating pure populations of rare CTC RNA from peripheral blood without background subtraction of leukocytes. We evaluated the biomarkers CD146 and CD49f as a strategy to isolate CTCs that underwent epithelial to mesenchymal transition (EMT). We hypothesized that using immunomagnetic separation and fluorescence activated cell sorting (IE/FACS) it is possible to isolate RNA derived from EpCAM-negative CTCs. Methods: 10 breast cancer cell lines were acquired from the ATCC, authenticated by short tandem repeat profiling, and stratified according to subtype: HER2 positive (SKBR3, MDA-MB-453, SUM190), luminal A (T47D, MCF7, ZR751), luminal B (BT474) and basal-like (SUM149, MDA-MB-231, Hs578T). IE/FACS with EMT gates was performed using CD146 ferrofluid particles via a magnetic separator followed by incubation with Thioflavin T, CD 31 and CD45 PE-Cy7 (for human or mouse blood), CD146-V450, and CD49f-A647. FACS sorting was performed using a FACS Aria II (BD Biosciences). Known quantities of cells were spiked into PBS or peripheral blood (PB) from healthy female donors and subjected to IE/FACS with EMT gates. Absolute cell counts and recovery rates were determined using the TruCOUNT method (BD Biosciences) with acquisition of 35,000 beads. MDA-MB-231 xenografts were established in 4 male NOD/SCID/IL2 gamma chain deficient mice; cardiac punctures were performed to acquire a complete xenograft PB volume for IE/FACS. Sorted xenograft CTCs, human PB and MDA-MB-231 were used to isolate RNA, amplify and profile via Affymetrix human gene ST 1.0 arrays. The effect of sample processing with IE/FACS was assessed using our EpCAM gates (EpCAM ferrofluid, EpCAM-PE, thioflavin, CD45 PE-Cy7) to sort BT474 and profiled via next generation sequencing (NGS) using the Helicos Single Molecule sequencing approach. Results: MDA-MB-231 spiked into PB from an unaffected mouse and negative mouse PB controls were used to establish gating thresholds. This gating strategy recovered 14% of MDA-MB-231 cells from spiked human PB via the TruCOUNT method, which represented a 200% yield versus EpCAM based IE/FACS. CTCs were successfully isolated from 4/4 mice bearing xenografts (ranging from 193-6352 cells captured per ∼1mL mouse blood). Principal component analysis demonstrated that gene expression may differentiate xenograft CTCs from PB and MDA-MB-231. Recovery rates using the EMT gates for 10 cell lines spiked into PBS and human PB will be reported and compared to our typical EpCAM gating strategy. Pearson's correlation coefficient of BT474 spiked into PB and recovered via IE/FACS using an EpCAM gating strategy was 92% by NGS. Conclusions: We have established a method for the isolation and expression profiling of EpCAM-negative CTCs as well as EpCAM-positive CTCs. Future studies are required to determine if expression profiling of CTCs can be used as prognostic, predictive and discovery tools. Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P1-04-07.