Detecting circulating tumor cells: current challenges and new trends

Stem cell technology in breast cancer: current status and potential applications

Breast cancer, the leading cause of cancer among females, is supported by the presence of a rare subset of undifferentiated cells within the tumor, identified as breast cancer stem cells (BCSCs). BCSCs underlie the mechanisms of tumor initiation and sustenance and are implicated in the dissemination of the primary tumor to metastatic sites, as they have been found circulating in the blood of breast cancer patients. The discovery of BCSCs has generated a great amount of interest among the scientific community toward their isolation, molecular characterization, and therapeutic targeting. In this review, after summarizing the literature on molecular characterization of BCSCs and methodologies used for their isolation, we will focus on recent data supporting their molecular and functional heterogeneity. Additionally, following a synopsis of the latest approaches for BCSC targeting, we will specifically emphasize on the therapeutic use of naïve or engineered normal stem cells in the treatment of breast cancer and present contradictory findings challenging their safety.

Clusters of circulating tumor cells traverse capillary-sized vessels

Multicellular aggregates of circulating tumor cells (CTC clusters) are potent initiators of distant organ metastasis. However, it is currently assumed that CTC clusters are too large to pass through narrow vessels to reach these organs. Here, we present evidence that challenges this assumption through the use of microfluidic devices designed to mimic human capillary constrictions and CTC clusters obtained from patient and cancer cell origins. Over 90% of clusters containing up to 20 cells successfully traversed 5- to 10-μm constrictions even in whole blood. Clusters rapidly and reversibly reorganized into single-file chain-like geometries that substantially reduced their hydrodynamic resistances. Xenotransplantation of human CTC clusters into zebrafish showed similar reorganization and transit through capillary-sized vessels in vivo. Preliminary experiments demonstrated that clusters could be disrupted during transit using drugs that affected cellular interaction energies. These findings suggest that CTC clusters may contribute a greater role to tumor dissemination than previously believed and may point to strategies for combating CTC cluster-initiated metastasis.

Collision rates for rare cell capture in periodic obstacle arrays strongly depend on density of cell suspension

Recently, computational modelling has been successfully used for determination of collision rates for rare cell capture in periodic obstacle arrays. The models were based on particle advection simulations where the cells were advected according to velocity field computed from two dimensional Navier-Stokes equations. This approach may be used under the assumption of very dilute cell suspensions where no mutual cell collisions occur. We use the object-in-fluid framework to demonstrate that even with low cell-to-fluid ratio, the optimal geometry of the obstacle array significantly changes. We show computational simulations for ratios of 3.5, 6.9 and 10.4% determining the optimal geometry of the periodic obstacle arrays. It was already previously demonstrated that cells in periodic obstacle arrays follow trajectories in two modes: the colliding mode and the zig-zag mode. The colliding mode maximizes the cell-obstacle collision frequency. Our simulations reveal that for dilute suspensions and for suspensions with cell-to-fluid ratio 3.5%, there is a range of column shifts for which the cells follow colliding trajectories. However we showed, that for 6.9 and 10.4%, the cells never follow colliding trajectories.

Development of a circulating tumor cells based RNA in situ hybridization technique

AIM: To develop a circulating tumor cells (CTCs) based RNA in situ hybridization technique for analyzing CTC phenotype and indirectly detecting tumor progression.

METHODS: We adopted the negative enrichment method to obtain slides of peripheral blood CTC and nucleated cells of hepatocellular carcinoma patients, and then RNA ISH on CTC slides was then developed. The peptidyl-prolyl cis-trans isomerase B (PPIB) gene, which is highly conserved in eukaryotes, was used as a positive control probe, which can detect the PPIB gene transcriptional activity on CTC slides.

RESULTS: The negative enrichment method allowed for successful isolation of peripheral blood CTCs from hepatocellular carcinoma patients. However, on CTC and nucleated cell slides which were fixed by conventional methods, RNA in situ hybridization signal was very weak. We tested the reagents used in negative enrichment, which showed that the reagents had no influence on the cells. Finally, we got the transcriptional information of PPIB on CTC slides after adjusting the conventional fixing method and time, and provided scientific data for real-time dynamic monitoring specific gene expression in peripheral blood CTCs of patients with solid tumors.

CONCLUSION: Shortening the time between blood collection and cell fixation can improve RNA degradation. On more than 10 slides of peripheral nucleated blood cells isolated by negative enrichment, real-time monitoring of CTC specific gene transcription level can be achieved through a high sensitive RNA in situ hybridization technique.

Aptamers in analytics

Nucleic acid aptamers are promising alternatives to antibodies in analytics. They are generally obtained through an iterative SELEX protocol that enriches a population of synthetic oligonucleotides to a subset that can recognize the chosen target molecule specifically and avidly. A wide range of targets is recognized by aptamers. Once identified and optimized for performance, aptamers can be reproducibly synthesized and offer other key features, like small size, low cost, sensitivity, specificity, rapid response, stability, and reusability. This makes them excellent options for sensory units in a variety of analytical platforms including those with electrochemical, optical, and mass sensitive transduction detection. Many novel sensing strategies have been developed by rational design to take advantage of the tendency of aptamers to undergo conformational changes upon target/analyte binding and employing the principles of base complementarity that can drive the nucleic acid structure. Despite their many advantages over antibodies, surprisingly few aptamers have yet been integrated into commercially available analytical devices. In this review, we discuss how to select and engineer aptamers for their identified application(s), some of the challenges faced in developing aptamers for analytics and many examples of their reported successful performance as sensors in a variety of analytical platforms.

Molecular Biomarkers in Bladder Cancer: Novel Potential Indicators of Prognosis and Treatment Outcomes

Although many clinical and molecular markers for predicting outcomes in bladder cancer (BC) have been reported, their application in clinical practice remains unclear. Bladder carcinogenesis has two distinct molecular pathways that direct the development of BC. FGFR3 mutations are common in low-grade BC, while TP53 mutation or loss of RB1 is associated with muscle-invasive BC. However, no tissue-based gene markers confirmed by prospective large-scale trials in BC have been used in clinical practice. Micro-RNA analyses of BC tissue revealed that miR-145 and miR-29c^⁎ function as tumor suppressors, whereas miR-183 and miR-17-5p function as oncogenic miRNAs. In liquid biopsy, circulating tumor cells (CTC), exosomes, or cell-free RNA is extracted from the peripheral blood samples of cancer patients to analyze cancer prognosis. It was reported that detection of CTC was associated with poor prognostic factors. However, application of liquid biopsy in BC treatment is yet to be explored. Although several cell-free RNAs, such as miR-497 in plasma or miR-214 in urine, could be promising novel circulating biomarkers, they are used only for diagnosing BC as the case that now stands. Here, we discuss the application of novel biomarkers in evaluating and measuring BC outcomes.

New blood markers detection technology: A leap in the diagnosis of gastric cancer

Gastric cancer (GC) is still one of the malignant tumors with high morbidity and mortality in the world, with a 5-year survival rate of less than 30%. GC is often either asymptomatic or causes only nonspecific symptoms in its early stages, whereas when the symptoms manifest, the cancer has usually reached an advanced stage, which is one of the main causes of its relatively poor prognosis. Hence, the main focus of GC research has been on discovering new tools and technology to predict, screen and diagnose GC at an early stage which would prompt early treatment. With the tremendous advances in the OMICS technology, serum proteomics has been in the limelight of cancer research over the last few decades and has steered the development of several methods helping to understand the mechanisms underlying gastric carcinogenesis, resulting in the identification of a large number of molecular targets such as circulating tumor cells (CTCs), cell free DNA (cfDNA) and cell tumor DNA (ctDNA) and their sub-molecular components such as miRNA, that show great promise as GC biomarkers. In this review, we are underlying the recent breakthroughs about new blood markers technology for GC while scrutinizing the potential clinical use of CTCs, cfDNA, ctDNA and the role of the methylation of their sub-molecular components in the pathogenesis, diagnosis and management of GC.

Aptamers: versatile molecular recognition probes for cancer detection

In the past two decades, aptamers have emerged as a novel class of molecular recognition probes comprising uniquely-folded short RNA or single-stranded DNA oligonucleotides that bind to their cognate targets with high specificity and affinity. Aptamers, often referred to as "chemical antibodies", possess several highly desirable features for clinical use. They can be chemically synthesized and are easily conjugated to a wide range of reporters for different applications, and are able to rapidly penetrate tissues. These advantages significantly enhance their clinical applicability, and render them excellent alternatives to antibody-based probes in cancer diagnostics and therapeutics. Aptamer probes based on fluorescence, colorimetry, magnetism, electrochemistry, and in conjunction with nanomaterials (e.g., nanoparticles, quantum dots, single-walled carbon nanotubes, and magnetic nanoparticles) have provided novel ultrasensitive cancer diagnostic strategies and assays. Furthermore, promising aptamer targeted-multimodal tumor imaging probes have been recently developed in conjunction with fluorescence, positron emission tomography (PET), single-photon emission computed tomography (SPECT), and magnetic resonance imaging (MRI). The capabilities of the aptamer-based platforms described herein underscore the great potential they hold for the future of cancer detection. In this review, we highlight the most prominent recent developments in this rapidly advancing field.

Blood-based biomarkers for diagnosis, prognosis and treatment of colorectal cancer

The global burden of colorectal cancer (CRC)-associated morbidity and mortality is increasing, in part due to a lack of early detection. Direct structural examination techniques, such as colonoscopy, are invasive and can therefore affect the willingness of patients to participate in screening. Recently, the use of "liquid biopsy" has gained considerable attention as a novel source of biomarkers. Blood-based biomarkers could prove to be practical tools for CRC detection, as the monitoring of biomarkers in biological fluids offers many advantages, including minimal invasiveness and easy accessibility. Biomarkers with high specificity and sensitivity can enable the detection of CRC at an early stage, thereby improving prognosis, prediction of treatment response, and recurrence risk. In this review, we summarize that the biomarkers currently thought to have potential for the early detection and monitoring of CRC, including circulating tumor cells, DNA, RNA and proteins.

Capture and Identification of Heterogeneous Circulating Tumor Cells Using Transparent Nanomaterials and Quantum Dots-Based Multiplexed Imaging

Background: Capture and identification of circulating tumor cells (CTCs) in the blood system can help guide therapy and predict the prognosis of cancer patients. However, simultaneous capture and identification of CTCs with both epithelial and mesenchymal phenotypes remains a formidable technical challenge for cancer research. This study aimed at developing a system to efficiently capture and identify these CTCs with heterogeneous phenotypes using transparent nanomaterials and quantum dots (QDs)-based multiplexed imaging.

Methods: Hydroxyapatite-chitosan (HA-CTS) nanofilm-coated substrates were modified based on our previous work to increase the capture efficiency of cancer cell lines by extending baking and incubating time. QDs-based imaging was applied to detect cytokeratin, epithelial cell adhesion molecule (EpCAM), and vimentin of cancer cells to demonstrate the feasibility of multiplexed imaging. And QDs-based multiplexed imaging of CD45, cytokeratin and vimentin was applied to detect CTCs from different cancer patients that were captured using HA-CTS nanofilm substrates.

Results: Comparisons of the capture efficiencies of cancer cells at different baking time of film formation and incubating time of cell capture revealed the optimal baking and incubating time. Optimal time was chosen to develop a modified CTCs capture system that could capture EpCAM-positive cancer cells at an efficiency > 80%, and EpCAM-negative cancer cells at an efficiency > 50%. QDs-based imaging exhibited comparable detection ability but higher photostability compared to organic dyes imaging in staining cells. In addition, QDs-based multiplexed imaging also showed the molecular profiles of cancer cell lines with different phenotypes well. The integrated CTCs capture and identification system successfully captured and imaged CTCs with different sub-phenotypes in blood samples from cancer patients.

Conclusion: This study demonstrated a reliable capture and detection system for heterogeneous CTCs that combined enrichment equipment based on HA-CTS nanofilm substrates with QDs-based multiplexed imaging.

Integrated EpCAM-independent subtraction enrichment and iFISH strategies to detect and classify disseminated and circulating tumors cells

Application of tumor cell surface adhesion molecule Anti-epithelial cell adhesion molecule (EpCAM)-dependent antibody capture, and intracellular cytokeratins (CKs)-dependent immunostaining strategies to detect disseminated or circulating tumor cells (DTCs or CTCs), is limited by highly heterogeneous and dynamic expression or absence of EpCAM and/or CKs in CTCs and DTCs, particularly in their capturing and identifying CTCs/DTCs shed from diverse types of solid tumor, thus being biased and restricted to the only both EpCAM and CK positive cancer cells. Moreover, heterogeneity of chromosome and tumor biomarker of CTCs/DTCs cannot be co-examined by conventional CK/EpCAM-dependent techniques. Accordingly, a novel integrated cellular and molecular approach of EpCAM-independent subtraction enrichment (SE) and immunostaining-FISH (iFISH(®)) has recently been successfully developed. SE-iFISH(®) is able to effectively enrich, comprehensively identify and characterize both large and small size non-hematopoietic heteroploid CTCs, DTCs and circulating tumor microemboli in various biofluid specimens of either cancer patients or patient-derived-xenograft mice. Obtained tumor cells, free of anti-EpCAM perturbing and hypotonic damage, are eligible for primary tumor cell culture as well as a series of downstream analyses. Highly heterogeneous CTCs and DTCs could be classified into subtypes by in situ phenotyping protein expression of various tumor biomarkers and karyotyping of chromosome aneuploidy performed by iFISH(®). Each CTC subtype may correlate with distinct clinical significance in terms of tumor metastasis, relapse, therapeutic drug sensitivity or resistance, respectively.

Microfluidic devices to enrich and isolate circulating tumor cells

Given the potential clinical impact of circulating tumor cells (CTCs) in blood as a clinical biomarker for the diagnosis and prognosis of various cancers, a myriad of detection methods for CTCs have been recently introduced. Among those, a series of microfluidic devices are particularly promising as they uniquely offer micro-scale analytical systems that are highlighted by low consumption of samples and reagents, high flexibility to accommodate other cutting-edge technologies, precise and well-defined flow behaviors, and automation capability, presenting significant advantages over conventional larger scale systems. In this review, we highlight the advantages of microfluidic devices and their potential for translation into CTC detection methods, categorized by miniaturization of bench-top analytical instruments, integration capability with nanotechnologies, and in situ or sequential analysis of captured CTCs. This review provides a comprehensive overview of recent advances in CTC detection achieved through application of microfluidic devices and the challenges that these promising technologies must overcome to be clinically impactful.

Oligonucleotide aptamers: A next-generation technology for the capture and detection of circulating tumor cells

A critical challenge for treating cancer is the early identification of those patients who are at greatest risk of developing metastatic disease. The number of circulating tumor cells (CTCs) in cancer patients has recently been shown to be a valuable (and non-invasively accessible) diagnostic indicator of the state of metastatic disease. CTCs are rare cancer cells found in the blood circulation of cancer patients believed to provide a means of diagnosing the likelihood for metastatic spread and assessing response to therapy in advanced, as well as early stage disease settings. Numerous technical efforts have been made to reliably detect and quantify CTCs, but the development of a universal assay has proven quite difficult. Notable challenges for developing a broadly useful CTC-based diagnostic assay are the development of easy-to-operate methods that (1) are sufficiently sensitive to reliably detect the small number of CTCs that are present in the circulation and (2) can capture the molecular heterogeneity of tumor cells. In this review, we describe recent progress towards the application of synthetic oligonucleotide aptamers as promising, novel, robust tools for the isolation and detection of CTCs. Advantages and challenges of the aptamer approach are also discussed.

Circulating tumor-associated neutrophils (cTAN) contribute to circulating tumor cell survival by suppressing peripheral leukocyte activation

During malignant progression, primary tumors rebuild leukocyte profile and suppress the host anti-tumor immune response. Tumor-associated neutrophils (TAN) increased in the cancer patients and emerged as an important participant and regulator of immune responses. The aim of this study is to investigate the role of circulating TAN (cTAN) in the metastatic process of advanced malignancy. We tested circulating neutrophils from patients (n = 180) with various types of cancer using flow cytometry analyses. We also used B16F10 cell-implanted C57BL/6 tumor-bearing mice model to simulate the advanced malignancy. Peripheral neutrophils were isolated by ficoll density gradient centrifugation, and in vitro tumor-leukocyte co-culture model was used to test tumor cell survival under leukocyte challenge condition. Here, we showed that neutrophils increased in the peripheral blood under the pathological condition of advanced malignancy both in cancer patients and in tumor-bearing mice. In mouse model, the malignantly increased neutrophils were identified as TAN according to the gene transcriptional analyses. We also showed that cTAN enhance tumor metastasis and cTAN could inhibit the activation of the peripheral leukocytes and rescue tumor cells from leukocyte challenge. In conclusion, our finding suggests that the abundance of cTAN in advanced cancer patients contributes to the circulating tumor cell survival by suppressing peripheral leukocyte activation.

Immunocapture strategies in translational proteomics

Aiming at clinical studies of human diseases, antibody-assisted assays have been applied to biomarker discovery and toward a streamlined translation from patient profiling to assays supporting personalized treatments. In recent years, integrated strategies to couple and combine antibodies with mass spectrometry-based proteomic efforts have emerged, allowing for novel possibilities in basic and clinical research. Described in this review are some of the field's current and emerging immunocapture approaches from an affinity proteomics perspective. Discussed are some of their advantages, pitfalls and opportunities for the next phase in clinical and translational proteomics.

When Prostate Cancer Circulates in the Bloodstream

Management of patients with prostate cancer is currently based on imperfect clinical, biological, radiological and pathological evaluation. Prostate cancer aggressiveness, including metastatic potential, remains difficult to accurately estimate. In an attempt to better adapt therapeutics to an individual (personalized medicine), reliable evaluation of the intrinsic molecular biology of the tumor is warranted, and particularly for all tumor sites (primary tumors and secondary sites) at any time of the disease progression. As a consequence of their natural tendency to grow (passive invasion) or as a consequence of an active blood vessel invasion by metastase-initiating cells, tumors shed various materials into the bloodstream. Major efforts have been recently made to develop powerful and accurate methods able to detect, quantify and/or analyze all these circulating tumor materials: circulating tumors cells, disseminating tumor cells, extracellular vesicles (including exosomes), nucleic acids, etc. The aim of this review is to summarize current knowledge about these circulating tumor materials and their applications in translational research.

High-Throughput Microfluidic Device for Circulating Tumor Cell Isolation from Whole Blood

Circulating tumor cells (CTCs) are promising markers to determine cancer patient prognosis and track disease response to therapy. We present a multi-stage microfluidic device we have developed that utilizes inertial and Dean drag forces for isolating CTCs from whole blood. We demonstrate a 94.2% ± 2.1% recovery of cancer cells with our device when screening whole blood spiked with MCF-7 GFP cells.

Capturing Cancer: Emerging Microfluidic Technologies for the Capture and Characterization of Circulating Tumor Cells

Circulating tumor cells (CTCs) escape from primary or metastatic lesions and enter into circulation, carrying significant information of cancer progression and metastasis. Capture of CTCs from the bloodstream and the characterization of these cells hold great significance for the detection, characterization, and monitoring of cancer. Despite the urgent need from clinics, it remains a major challenge to capture and retain these rare cells from human blood with high specificity and yield. Recent exciting advances in micro/nanotechnology, microfluidics, and materials science have enable versatile, robust, and efficient cell isolation and processing through the development of new micro/nanoengineered devices and biomaterials. This review provides a summary of recent progress along this direction, with a focus on emerging methods for CTC capture and processing, and their application in cancer research. Furthermore, classical as well as emerging cellular characterization methods are reviewed to reveal the role of CTCs in cancer progression and metastasis, and hypotheses are proposed in regard to the potential emerging research directions most desired in CTC-related cancer research.

Effect of mu Agonists on Long-Term Survival and Recurrence in Nonsmall Cell Lung Cancer Patients

Opioids are widely used for postoperative analgesia. Morphine may have an effect on cell replication, migration, and cancer recurrence. However, the association of postoperative mu agonists with outcome of nonsmall cell lung cancer (NSCLC) patients has not been fully investigated.We retrospectively evaluated the impact of postoperative mu agonists on overall survival (OS) and disease-free survival (DFS) in early stage NSCLC patients. Patients and relevant medical information were selected from the Bio-Bank of Shandong Provincial Hospital. Difference of clinicopathologic information in postoperative mu agonists group and no mu agonists group was analyzed by χ test. Univariate and multivariate Cox regression analysis were conducted and represented as hazards ratio and 95% confidence interval form. The primary endpoint was OS and secondary endpoint was DFS.This retrospective study included 984 consecutive NSCLC patients who underwent surgery between January 2006 and December 2011. No significant difference existed between postoperative mu agonists usage group and no mu agonists usage group in clinicopathologic information except operation type (P = 0.041). Postoperative mu agonists usage was related to shorter OS (HR 1.514, 95% CI 1.197-1.916, P = 0.001) and shorter DFS (HR 1.415, 95% CI 1.123-1.781, P = 0.003) in the multivariate Cox regression model. For the patients who received postoperative chemotherapy or radiotherapy postoperative mu agonists also predict shorter survival (HR 1.437, 95% CI 1.041-1.982, P = 0.027). Subgroup analysis showed that administration of postoperative mu agonists was related to shorter OS, especially in males, more smoking, poor differential degree, bilobectomy or pneumonectomy, and stage III subgroup, respectively.Administration of postoperative mu agonists was related to shorter OS and DFS for the NSCLC patients who underwent surgery.

Isolation, primary culture, morphological and molecular characterization of circulating tumor cells in gynecological cancers

The focus of the study was to implement a new workflow for circulating tumor cells (CTCs) characterization that would allow the analysis of CTCs on a cytomorphological and molecular level in patients with diagnosed gynecological cancer. Our findings may be useful in future cancer patient management. The study introduces a size-based enrichment (MetaCell(®)) method for the separation of viable CTCs, followed by CTCs culturing in vitro and gene expression characterization. It is based on the observation of CTCs and DTCs (Disseminated Tumor Cells) in several case studies of ovarian, endometrial and cervical cancer by means of cytomorphology and gene expression profiling. The viability of the enriched CTCs was estimated using vital and lethal fluorescence nuclear staining. This type of staining may be predictive for the success rate of subsequent CTC growth in vitro. To identify CTCs in the enriched CTC fraction, cytomorphological evaluations based on vital fluorescence staining were followed by gene expression analysis of tumor-associated (TA) genes. Cytokeratin expression (KRT7, KRT19) was analyzed in combination with MUC1, MUC16, CD24, CD44 and ALDH1. Gene expression analysis has shown that short-term in vitro culture enhanced the differentiation process of the captured CTCs growing on a membrane. On the other hand, redundant white blood cells captured on the membrane were eliminated during a short-term culture. The most frequently elevated genes in ovarian cancer (serous type) are EPCAM, KRT19 and MUC1. It has been demonstrated that CTC presence revealed by cytomorphological evaluation may be usefully complemented by TA-gene expression analysis, to increase the sensitivity of the analysis.

Oligonucleotide aptamer-drug conjugates for targeted therapy of acute myeloid leukemia

Oligonucleotide aptamers can specifically bind biomarkers on cancer cells and can be readily chemically modified with different functional molecules for personalized medicine. To target acute myeloid leukemia (AML) cells, we developed a single-strand DNA aptamer specific for the biomarker CD117, which is highly expressed on AML cells. Sequence alignment revealed that the aptamer contained a G-rich core region with a well-conserved functional G-quadruplex structure. Functional assays demonstrated that this synthetic aptamer was able to specifically precipitate CD117 proteins from cell lysates, selectively bound cultured and patient primary AML cells with high affinity (Kd < 5 nM), and was specifically internalized into CD117-expressing cells. For targeted AML treatment, aptamer-drug conjugates were fabricated by chemical synthesis of aptamer (Apt) with methotrexate (MTX), a central drug used in AML chemotherapy regimens. The formed Apt-MTX conjugates specifically inhibited AML cell growth, triggered cell apoptosis, and induced cell cycle arrest in G1 phase. Importantly, Apt-MTX had little effect on CD117-negative cells under the same treatment conditions. Moreover, exposure of patient marrow specimens to Apt-MTX resulted in selective growth inhibition of primary AML cells and had no toxicity to off-target background normal marrow cells within the same specimens. These findings indicate the potential clinical value of Apt-MTX for targeted AML therapy with minimal to no side effects in patients, and also open an avenue to chemical synthesis of new, targeted biotherapeutics.

Distinct expression of cytokeratin, N-cadherin and CD133 in circulating tumor cells of metastatic breast cancer patients

AIM

Circulating tumor cells (CTCs) appear as potential candidates to predict the ability of breast tumors to metastasize. Moreover, epithelial-mesenchymal transition (EMT) and stem cell features are major mechanisms for metastasis.

PATIENTS & METHODS

Using a triple fluorescence technique, the expression of EMT (N-cadherin) and stem cell markers (CD133) was analyzed in CTCs detected via cytokeratin in blood samples from 26 metastatic breast cancer patients.

RESULTS

We detected CTCs in 100% of the patients (n = 831 CTCs). In total, 67% of the CTCs were N-cadherin and CD133 negative. Nonetheless, 87.8 and 57.6%, respectively, of the CTCs that expressed one marker coexpressed the other. Both double-negative and double-positive CTCs were present in more than 90% of the patients. Within the CTCs of each patient, we demonstrated striking heterogeneities of marker expressions, cell shapes, clusters and sizes.

CONCLUSION

These data outline the importance of characterizing CTCs, especially through stem cell and EMT markers.

High-Throughput Microfluidic Device for Rare Cell Isolation

Enumerating and analyzing circulating tumor cells (CTCs)-cells that have been shed from primary solid tumors-can potentially be used to determine patient prognosis and track the progression of disease. There is a great challenge to create an effective platform that can isolate these cells, as they are extremely rare: only 1-10 CTCs are present in a 7.5mL of a cancer patient's peripheral blood. We have developed a novel microfluidic system that can isolate CTC populations label free. Our system consists of a multistage separator that employs inertial migration to sort cells based on size. We demonstrate the feasibility of our device by sorting colloids that are comparable in size to red blood cells (RBCs) and CTCs.

Integrated 3D conducting polymer-based bioelectronics for capture and release of circulating tumor cells

Here we develop a novel fabrication approach for producing three-dimensional (3D) conducting polymer-based bioelectronic interfaces (BEIs) that can be integrated on electronic devices for rare circulating tumor cell (CTC) isolation, detection, and collection via an electrically triggered cell released from chips. Based on the chemical oxidative polymerization of carboxylic acid-modified 3,4-ethylenedioxythiophene and modified poly(dimethylsiloxane) (PDMS) transfer printing technology, the high-aspect-ratio structures of poly(3,4-ethylenedioxythiophene) (PEDOT)-based "nanorod" arrays can be fabricated on indium tin oxide (ITO) electrodes when using the Si "microrod" arrays as masters. Furthermore, we integrated the biotinylated poly-(l)-lysine-graft-poly-ethylene-glycol (PLL-g-PEG-biotin) coating with 3D PEDOT-based BEIs for dynamic control of the capture/release performance of CTCs on chips; this combination exhibited an optimal cell-capture yield cells of ∼45 000 cells cm^-2 from EpCAM-positive MCF7 while maintaining resistance from the adhesion of EpCAM-negative HeLa cells at a density of ∼4000 cells cm^-2. By taking advantage of the electrochemical doping/dedoping properties of PEDOT materials, the captured CTCs can be triggered to be electrically released through the desorption phenomena of the PLL-g-PEG-biotin. More than 90% of the captured cells can be released while maintaining very high cell viability. Therefore, it is conceivable that the use of a 3D PEDOT-based BEI platform will meet the requirements for the development of downstream characterization of CTCs, as well as the next generation of bioelectronics for biomedical applications.

Circulating tumor cells in oral squamous cell carcinoma-an enigma or reality?

Oral squamous cell carcinoma (OSCC) is ranking 1^st among males and 4^th among females in India. In spite of major advances in diagnosis and treatment of OSCC, survival rates, have remained poor. Circulating tumor cells (CTCs) in the blood stream, play an important role in establishing metastases. It is important to identify patients suffering from nonlocalized tumor with “circulating” tumor cells to determine the tailor made, systemic therapy in addition to local resection and irradiation. Thus, detecting metastases at an early stage are needed for better prognosis and survival. CTCs as new prognostic marker to detect the metastatic potential will provide a novel insight into tumor burden and efficacy of therapy. The recent advances and its application in OSCC will be reviewed.

[Inhibitory effect of endostar on lymphangiogenesis in non-small cell lung cancer and its effect on circulating tumor cells]

背景与目的

血管内皮抑素可以抑制肿瘤新生血管的生成，但对肿瘤微淋巴管的形成与发展是否存在抑制效应引起我们关注。本研究旨在探讨重组人血管内皮抑素（recombinant human endostatin injection）对非小细胞肺癌组织中血管内皮生长因子（vascular endothelial growth factor, VEGF）-C、VEGF-D和VEGF受体（VEGFR）-3表达及对外周血循环肿瘤细胞数目的影响。

方法

荷瘤裸鼠随机分为空白对照组、顺铂组、不同浓度重组人血管内皮抑素组及重组人血管内皮抑素+顺铂组，连续给药2周。1周后检测肿瘤组织中VEGF-C、VEGF-D、VEGFR-3的表达水平和微淋巴管密度。免疫荧光染色诊断和计数循环肿瘤细胞。

结果

重组人血管内皮抑素组与重组人血管内皮抑素联合顺铂组的表达阳性率、微淋巴管密度均明显低于空白对照组与顺铂组（P < 0.05）；较高浓度的重组人血管内皮抑素联合顺铂组与重组人血管内皮抑素组表达阳性率和微淋巴管密度低于相应较低重组人血管内皮抑素浓度的组别（P < 0.05）。各组微淋巴管密度与VEGF-C、VEGF-D、VEGFR-3表达阳性率存在正相关。重组人血管内皮抑素联合顺铂各组的循环肿瘤细胞数目明显低于单独使用顺铂或重组人血管内皮抑素（P < 0.05）。

结论

重组人血管内皮抑素可以抑制肿瘤新生淋巴管生成，减少循环肿瘤细胞，作用大小与浓度有关。与顺铂联合使用能够更有效的减少循环肿瘤细胞。

Application of fluorescent proteins in tumor research

Fluorescent proteins have been applied in multiple tumor research fields, including tumor cell growth, invasion, metastasis, angiogenesis, the interaction between tumor cells and host cells, and antitumor drugs. Fluorescent imaging has enabled what was formerly invisible to be seen clearly in vivo with fluorescent proteins. This article will make a brief review of the application of fluorescent proteins in tumor research.

Entry effects of droplet in a micro confinement: Implications for deformation-based circulating tumor cell microfiltration

Deformation-based circulating tumor cell (CTC) microchips are a representative diagnostic device for early cancer detection. This type of device usually involves a process of CTC trapping in a confined microgeometry. Further understanding of the CTC flow regime, as well as the threshold passing-through pressure, is a key to the design of deformation-based CTC filtration devices. In the present numerical study, we investigate the transitional deformation and pressure signature from surface tension dominated flow to viscous shear stress dominated flow using a droplet model. Regarding whether CTC fully blocks the channel inlet, we observe two flow regimes: CTC squeezing and shearing regime. By studying the relation of CTC deformation at the exact critical pressure point for increasing inlet velocity, three different types of cell deformation are observed: (1) hemispherical front, (2) parabolic front, and (3) elongated CTC co-flowing with carrier media. Focusing on the circular channel, we observe a first increasing and then decreasing critical pressure change with increasing flow rate. By pressure analysis, the concept of optimum velocity is proposed to explain the behavior of CTC filtration and design optimization of CTC filter. Similar behavior is also observed in channels with symmetrical cross sections like square and triangular but not in rectangular channels which only results in decreasing critical pressure.

Detection of circulating tumor cell-specific markers in breast cancer patients using the quantitative RT-PCR assay

BACKGROUND

Breast cancer is a highly prevalent disease among women worldwide. While the expression of certain proteins within breast cancer tumors is used to determine the prognosis and select therapies, additional markers need to be identified. Circulating tumor cells (CTCs) are constituent cells that have detached from a primary tumor to circulate in the bloodstream. CTCs are considered the main source of breast cancer metastases; therefore, detection of CTCs could be a promising diagnostic method for metastatic breast cancer.

METHODS

In this study, the CircleGen CTC RT-qDx assay was used to analyze the mRNA expression levels of six CTC-specific markers including EpCAM, CK19, HER2, Ki67, hTERT, and vimentin with a total of 692 peripheral whole blood samples from 221 breast cancer patients and 376 healthy individuals.

RESULTS

This assay showed high specificity with multiple markers; none of the healthy controls were detected positive, whereas 21.7 and 14 % of breast cancer patients were positive for EpCAM and CK19, respectively. Of the 221 breast cancer patients, 84 (38 %), 46 (20.8 %), 83 (37.6 %), and 39 (17.6 %) were positively for HER2, Ki67, hTERT, and vimentin mRNA, respectively. Of the 84 patients who were HER2 positive, nine (4 %) were also positive for EpCAM, CK19, Ki67, hTERT, and vimentin. Of the 139 breast cancer patients who were HER2 negative, 65 (29.1 %) were negative for EpCAM, CK19, Ki67, hTERT, and vimentin. Furthermore, the EpCAM-positive population decreased from 21.5 to 8.3 % after completion of anti-tumor treatment (TP4). Similarly, the CK19, HER2, hTERT, and vimentin positives also decreased from 13.9 to 9.5 %, from 37.7 to 21.4 %, from 37.2 to 33.3 %, and from 17.5 to 14.3 %, respectively, after completion of anti-tumor treatment. In contrast, the Ki67 positives increased from 20.6 to 41.7 % after completion of anti-tumor treatment.

CONCLUSIONS

mRNA overexpression of six CTC-specific markers was detected by the CircleGen CTC RT-qDx assay with high specificity, and the obtained mRNA expression levels of CTC-specific markers might provide useful criteria to select appropriate anti-tumor treatment for breast cancer patients.

Frontiers in clinical and molecular diagnostics and staging of metastatic clear cell renal cell carcinoma

The last few years have brought advances in the understanding of the molecular biology of metastatic clear cell renal cell carcinoma (RCC). Both preclinical research and clinical trials brought together results from the latest advancements in RCC diagnostic and staging. Understanding of the complex molecular alterations involved in the development and progression of RCC enables development of immunohistochemical and genetic diagnostic tools and is also opening the doors for experimental targeted therapies. At the same time, improvements of medical and molecular imaging improves the sensitivity and specificity of metastatic disease diagnosis. Moreover, independent validation of molecular profiles across high-throughput platforms, methods, laboratories and cancer populations has recently been successfully performed in RCC. Generation of informative, clinical diagnostic tools is likely to contribute to development of novel personalized diagnostic and treatment protocols and ensure prolonged survival of RCC patient in the near future.

May CTC technologies promote better cancer management?

In the case of cancer, death is usually not due to the primary tumor itself but due to dissemination. Analysis of the circulating tumor cells (CTCs), i.e., cells responsible for a formation of metastases, should provide information useful for the management of cancer patients, fulfilling the objectives of predictive, preventive, and personalized medicine (PPPM). Despite promising results, the decisions on stage of disease and how to guide the adjuvant treatment still do not include results of CTC assessment. We want to describe two major reasons why the recent diagnostic value of CTC analysis is not sufficient for clinical use. The first reason arises from the biological nature of the tumor itself and the second reason is associated with an interdisciplinary status of CTC diagnostics in the sense that it is neither a theme purely for pathologists nor for haemato-oncologists nor clinical biochemists. We anticipate that there are at least three areas where CTCs can be useful for clinical practice. The first is monitoring of treatment efficacy of cancer patients. The second is a molecular characterization of captured CTCs for targeted treatment, and the third is a cultivation of captured CTCs for drug sensitivity testing. All of these approaches allow researchers recognize and respond to changes of phenotype of cancer cells during disease progression and introduce PPPM into clinical practice.

Circulating tumor cells and cell tumor DNA methylation in gastric cancer: From bench to bedside

Gastric cancer is still one of malignant tumors with the highest morbidity and mortalit in China, and the 5-year survival rate is only 10%. Circulating tumor cells (CTCs) and cell tumor DNA (ctDNA) have gained increasing interests during the past decade. A wealth of information indicating the potential value of CTCs and ctDNA for cancer diagnosis, monitoring of the efficacy of anticancer therapies and prognosis has emerged. In this review, we discuss the biology and potential clinical use of CTCs and ctDNA in gastric cancer, as well as their role in the management of cancer patients.

Magnetic-EpCAM nanoprobe as a new platform for efficient targeting, isolating and imaging hepatocellular carcinoma

Herein, magnetic-EpCAM nanoparticle (EpCAM-MNP) was developed and exploited as nanoprobe for targeting, isolating and imaging hepatocellular carcinoma.

The promise of novel molecular markers in bladder cancer

Bladder cancer is the fourth most common malignancy in the US and is associated with the highest cost per patient. A high likelihood of recurrence, mandating stringent surveillance protocols, has made the development of urinary markers a focus of intense pursuit with the hope of decreasing the burden this disease places on patients and the healthcare system. To date, routine use of markers is not recommended for screening or diagnosis. Interests include the development of a single urinary marker that can be used in place of or as an adjunct to current screening and surveillance techniques, as well identifying a molecular signature for an individual’s disease that can help predict progression, prognosis, and potential therapeutic response. Markers have shown potential value in improving diagnostic accuracy when used as an adjunct to current modalities, risk-stratification of patients that could aid the clinician in determining aggressiveness of surveillance, and allowing for a decrease in invasive surveillance procedures. This review discusses the current understanding of emerging biomarkers, including miRNAs, gene signatures and detection of circulating tumor cells in the blood, and their potential clinical value in bladder cancer diagnosis, as prognostic indicators, and surveillance tools, as well as limitations to their incorporation into medical practice.

Cancer cell invasion and EMT marker expression: a three-dimensional study of the human cancer-host interface

Cancer cell invasion takes place at the cancer-host interface and is a prerequisite for distant metastasis. The relationships between current biological and clinical concepts such as cell migration modes, tumour budding and epithelial-mesenchymal transition (EMT) remains unclear in several aspects, especially for the 'real' situation in human cancer. We developed a novel method that provides exact three-dimensional (3D) information on both microscopic morphology and gene expression, over a virtually unlimited spatial range, by reconstruction from serial immunostained tissue slices. Quantitative 3D assessment of tumour budding at the cancer-host interface in human pancreatic, colorectal, lung and breast adenocarcinoma suggests collective cell migration as the mechanism of cancer cell invasion, while single cancer cell migration seems to be virtually absent. Budding tumour cells display a shift towards spindle-like as well as a rounded morphology. This is associated with decreased E-cadherin staining intensity and a shift from membranous to cytoplasmic staining, as well as increased nuclear ZEB1 expression.

Nanotopographic Biomaterials for Isolation of Circulating Tumor Cells

Circulating tumor cells (CTCs) shed from the primary tumor mass and circulating in the bloodstream of patients are believed to be vital to understand of cancer metastasis and progression. Capture and release of CTCs for further enumeration and molecular characterization holds the key for early cancer diagnosis, prognosis and therapy evaluation. However, detection of CTCs is challenging due to their rarity, heterogeneity and the increasing demand of viable CTCs for downstream biological analysis. Nanotopographic biomaterial-based microfluidic systems are emerging as promising tools for CTC capture with improved capture efficiency, purity, throughput and retrieval of viable CTCs. This review offers a brief overview of the recent advances in this field, including CTC detection technologies based on nanotopographic biomaterials and relevant nanofabrication methods. Additionally, the possible intracellular mechanisms of the intrinsic nanotopography sensitive responses that lead to the enhanced CTC capture are explored.

All-in-one centrifugal microfluidic device for size-selective circulating tumor cell isolation with high purity

Circulating tumor cells (CTCs) have gained increasing attention owing to their roles in cancer recurrence and progression. Due to the rarity of CTCs in the bloodstream, an enrichment process is essential for effective target cell characterization. However, in a typical pressure-driven microfluidic system, the enrichment process generally requires complicated equipment and long processing times. Furthermore, the commonly used immunoaffinity-based positive selection method is limited, as its recovery rate relies on EpCAM expression of target CTCs, which shows heterogeneity among cell types. Here, we propose a centrifugal-force-based size-selective CTC isolation platform that can isolate and enumerate CTCs from whole blood within 30 s with high purity. The device was validated using the MCF-7 breast cancer cell line spiked in phosphate-buffered saline and whole blood, and an average capture efficiency of 61% was achieved, which is typical for size-based filtration. The capture efficiency for whole blood samples varied from 44% to 84% under various flow conditions and dilution factors. Under the optimized operating conditions, a few hundred white blood cells per 1 mL of whole blood were captured, representing a 20-fold decrease compared to those obtained using a commercialized size-based CTC isolation device. In clinical validation, normalized CTC counts varied from 10 to 60 per 7.5 mL of blood from gastric and lung cancer patients, yielding a detection rate of 50% and 38%, respectively. Overall, our CTC isolation device enables rapid and label-free isolation of CTCs with high purity, which should greatly improve downstream molecular analyses of captured CTCs.

WITHDRAWN: Enhanced Detection and Phenotypic and Karyotypic in Situ Characterization of Circulating Tumor Cells

Available online October 16, 2014 This article has been withdrawn at the request of the author(s) and/or editor. The Publisher apologizes for any inconvenience this may cause. The full Elsevier Policy on Article Withdrawal can be found at http://www.elsevier.com/locate/withdrawalpolicy.

High-purity isolation and recovery of circulating tumor cells using conducting polymer-deposited microfluidic device

We have developed a conductive nano-roughened microfluidic device and demonstrated its use as an electrically modulated capture and release system for studying rare circulating tumor cells (CTCs). The microchannel surfaces were covalently decorated with epithelial cancer-specific anti-EpCAM antibody by electrochemical deposition of biotin-doped polypyrrole (Ppy), followed by the assembly of streptavidin and biotinylated antibody. Our method utilizes the unique topographical features and excellent electrical activity of Ppy for i) surface-induced preferential recognition and release of CTCs, and ii) selective elimination of non-specifically immobilized white blood cells (WBCs), which are capable of high-purity isolation of CTCs. In addition, the direct incorporation of biotin molecules offers good flexibility, because it allows the modification of channel surfaces with diverse antibodies, in addition to anti-EpCAM, for enhanced detection of multiple types of CTCs. By engineering a series of electrical, chemical, and topographical cues, this simple yet efficient device provides a significant advantage to CTC detection technology as compared with other conventional methods.

In vitro culture and characterization of human lung cancer circulating tumor cells isolated by size exclusion from an orthotopic nude-mouse model expressing fluorescent protein

In the present study, we demonstrate an animal model and recently introduced size-based exclusion method for circulating tumor cells (CTCs) isolation. The methodology enables subsequent in vitro CTC-culture and characterization. Human lung cancer cell line H460, expressing red fluorescent protein (H460-RFP), was orthotopically implanted in nude mice. CTCs were isolated by a size-based filtration method and successfully cultured in vitro on the separating membrane (MetaCell®), analyzed by means of time-lapse imaging. The cultured CTCs were heterogeneous in size and morphology even though they originated from a single tumor. The outer CTC-membranes were blebbing in general. Abnormal mitosis resulting in three daughter cells was frequently observed. The expression of RFP ensured that the CTCs originated from lung tumor. These readily isolatable, identifiable and cultivable CTCs can be used to characterize individual patient cancers and for screening of more effective treatment.

The effects of 3D channel geometry on CTC passing pressure--towards deformability-based cancer cell separation

Various lab on a chip devices have been developed recently to detect and separate circulating tumour cells (CTCs) for early stage cancer detection. Because CTCs are extremely rare in the blood, next generation CTC microfilters aim at significant improvement in both efficiency and throughput. CTC microfilters based on cell deformability seem to be a promising direction. In the present research, we study a CTC passing event through a micro-filtering channel with various 3D geometries. The pressure signatures for different types of cells passing through different channels are characterized numerically. Specifically, five kinds of cross-sections, circular, square, triangular and two kinds of rectangular channels with aspect ratios of 2 and 5, are studied in this work. The total pressures for cells passing through the channels are calculated and reveal different behaviour from what is predicted by the static surface tension model. Among all five cross-sections studied, the circular cross-section features the highest critical pressure and thus is most suitable for high efficiency CTC separation. The square filtering channel provides the second largest critical pressure, and the triangular cross-section provides the least critical pressure among these three cross-sections. All these three cross-sections are better than the rectangular channels with aspect ratios of 2 and 5. For the rectangular channel, a high aspect ratio channel may lead to cell splitting at high speed, which will result in a periodic pressure signature. Our findings will provide valuable information for the design of next generation CTC microfilters.

Nanotechnology applications in diagnosis and treatment of metastasis

The lethality of solid tumors is in large part dependent on their ability to metastasize through hematologic and lymphatic transport pathways. The dissemination of cancer cells from the primary tumor to undergo transport, their ability to survive in transit and then to subsequently form metastatic colonies, is facilitated by a complex concert of signaling pathways and cell–cell and cell–matrix interactions. Elucidating these mechanistic components is highly valuable to guide the development of technologies for efficiently detecting and treating metastasis. To this end, in recent years nanotechnology approaches have provided several unique detection, characterization and treatment strategies. The current article will review these approaches to discuss their promise and challenges, specifically in metastatic cancer, above and beyond the usual nanomedicine applications in cancer therapy.

A new method to assay protease based on amyloid misfolding: application to prostate cancer diagnosis using a panel of proteases biomarkers

This paper reports a sensitive method with electrochemical technique to detect various proteases, which can be used for the diagnosis of prostate cancer. For the proposed assay method, the working electrode is modified with the peptide probes for the target proteases. These probes contain the substrate sequence of target proteases, as well as the seed peptide sequence that can accelerate the misfolding of amyloid-beta. If there are proteases in the test solution, after protease cleavage of the substrate peptides, the distal seed peptide will be removed from the electrode surface. So, in the absence of proteases, the seed peptides can initiate and accelerate amyloid-beta misfolding on the electrode surface. Consequently, the formed aggregates strongly block the electron transfer of the in-solution electroactive species with the electrode, resulting in suppressed signal readout. Nevertheless, in the presence of proteases, enzyme cleavage may lead to greatly mitigated protein misfolding and evident signal enhancement. Since the contrast in signal readout between the two cases can be amplified by using the protein misfolding step, high sensitivity suitable for direct detection of proteases in serum can be achieved. These results may suggest the feasibility of our new method for the detection of a panel of proteases in offering detailed diagnosis of prostate cancer and a better treatment of the cancer.