The biological and clinical importance of epithelial-mesenchymal transition in circulating tumor cells

CTC, ctDNA, and Exosome in Thyroid Cancers: A Review

Thyroid cancer has become more common in recent years all around the world. Many issues still need to be urgently addressed in the diagnosis, treatment, and prognosis of thyroid cancer. Liquid biopsy (mainly circulating tumor DNA (ctDNA), circulating tumor cells (CTCs), and circulating exosomes) may provide a novel and ideal approach to solve these issues, allows us to assess the features of diseases more comprehensively, and has a function in a variety of malignancies. Recently, liquid biopsy has been shown to be critical in thyroid cancer diagnosis, treatment, and prognosis in numerous previous studies. In this review, by testing CTCs, ctDNA, and exosomes, we focus on the possible clinical role of liquid biopsy in thyroid cancer, including diagnostic and prognostic biomarkers and response to therapy. We briefly review how liquid biopsy components have progressed in thyroid cancer by consulting the existing public information. We also discuss the clinical potential of liquid biopsy in thyroid cancer and provide a reference for liquid biopsy research. Liquid biopsy has the potential to be a useful tool in the early detection, monitoring, or prediction of response to therapies and prognosis in thyroid cancer, with promising clinical applications.

Isolation, Detection and Analysis of Circulating Tumour Cells: A Nanotechnological Bioscope

Cancer is one of the dreaded diseases to which a sizeable proportion of the population succumbs every year. Despite the tremendous growth of the health sector, spanning diagnostics to treatment, early diagnosis is still in its infancy. In this regard, circulating tumour cells (CTCs) have of late grabbed the attention of researchers in the detection of metastasis and there has been a huge surge in the surrounding research activities. Acting as a biomarker, CTCs prove beneficial in a variety of aspects. Nanomaterial-based strategies have been devised to have a tremendous impact on the early and rapid examination of tumor cells. This review provides a panoramic overview of the different nanotechnological methodologies employed along with the pharmaceutical purview of cancer. Initiating from fundamentals, the recent nanotechnological developments toward the detection, isolation, and analysis of CTCs are comprehensively delineated. The review also includes state-of-the-art implementations of nanotechnological advances in the enumeration of CTCs, along with future challenges and recommendations thereof.

Cycloartocarpin Inhibits Migration through the Suppression of Epithelial-to-Mesenchymal Transition and FAK/AKT Signaling in Non-Small-Cell Lung Cancer Cells

Lung cancer metastasis is a multifaceted process that accounts for 90% of cancer deaths. According to several studies, the epithelial-mesenchymal transition (EMT) plays an essential role in lung cancer metastasis. Therefore, this study aimed to investigate the potential pharmacological effect of cycloartocarpin on the suppression of metastasis-related behaviors and EMT. An MTT assay was used to examine cell viability. Cell migration was determined using a wound healing assay. Anchorage-independent cell growth was also performed. Western blot analysis was used to identify the key signaling proteins involved in the regulation of EMT and migration. The results found that non-toxic concentrations of cycloartocarpin (10-20 μM) effectively suppressed cell migration and attenuated anchorage-independent growth in H292, A549, and H460 cells. Interestingly, these effects were consistent with the findings of Western blot analysis, which revealed that the level of phosphorylated focal adhesion kinase (p-FAK), phosphorylated ATP-dependent tyrosine kinase (p-AKT), and cell division cycle 42 (Cdc42) were significantly reduced, resulting in the inhibition of the EMT process, as evidenced by decreased N-cadherin, vimentin, and slug expression. Taken together, the results suggest that cycloartocarpin inhibits EMT by suppressing the FAK/AKT signaling pathway, which is involved in Cdc42 attenuation. Our findings demonstrated that cycloartocarpin has antimetastatic potential for further research and development in lung cancer therapy.

Prognostic Implications of Portal Venous Circulating Tumor Cells in Resectable Pancreatic Cancer

Circulating tumor cells (CTCs) are a promising prognostic biomarker for cancers. However, the paucity of CTCs in peripheral blood in early-stage cancer is a major challenge. Our study aimed to investigate whether portal venous CTCs can be a biomarker for early recurrence and poor prognosis in pancreatic cancer. Patients who underwent upfront curative surgery for resectable pancreatic cancer were consecutively enrolled in this prospective study. Intraoperatively, 7.5 mL of portal and peripheral blood was collected, and CTC detection and identification were performed using immunofluorescence staining. Peripheral blood CTC sampling was performed in 33 patients, of which portal vein CTC sampling was performed in 28. The median portal venous CTCs (2.5, interquartile ranges (IQR) 1−7.75) were significantly higher than the median peripheral venous CTCs (1, IQR 0−2, p < 0.001). Higher stage and regional lymph node metastasis were related with a larger number of CTCs (≥3) in portal venous blood. Patients with low portal venous CTCs (≤2) showed better overall (p = 0.002) and recurrence-free (p = 0.007) survival than those with high portal venous CTCs (≥3). If validated, portal CTCs can be used as a prognostic biomarker in patients with resectable pancreatic cancer.

Epithelial-Mesenchymal Transition-Based Gene Signature and Distinct Molecular Subtypes for Predicting Clinical Outcomes in Breast Cancer

Purpose

Regulation of inducers and transcription factor families influence epithelial–mesenchymal transition (EMT), a contributing factor to breast cancer invasion and progression.

Methods

Molecular subtypes were classified based on EMT-related mRNAs using ConsensusClusterPlus package. Differences in tumor immune microenvironment and prognosis were assessed among subtypes. Based on EMT genes, a gene signature for prognosis was built using TCGA training set by performing multivariate and univariate Cox regression analyses. Prediction accuracy of the signature was validated by receiver operating characteristic (ROC) curves and overall survival analysis on internal and external datasets. By conducting univariate and multivariate Cox regression analyses, the risk signature as an independent prognostic indicator was assessed. A nomogram was constructed and validated by calibration analysis and decision curve analysis (DCA).

Results

Five molecular subtypes were characterized based on EMT genes. Patients in Cluster 2 exhibited an activated immune state and a better prognosis. An 11-EMT gene-signature was built to predict breast cancer prognosis. After validation, the signature showed independence and robustness in predicting clinical outcomes of patients. A nomogram combining the RiskScore and pTNM_stage accurately predicted 1-, 2-, 3-, and 5-year survival chance. In comparison with published model, the current model showed a higher area under the curve (AUC).

Conclusion

We characterized five breast cancer subtypes with distinct clinical outcomes and immune status. The study developed an 11-EMT gene-signature as an independent prognostic factor for predicting clinical outcomes of breast cancer.

Identification of Circulating Tumor Cell Phenotype in Differentiated Thyroid Carcinoma

Objective: Circulating tumor cells (CTCs) have been considered as the origin of tumor metastasis and recurrence, which always indicate a poor prognosis. There are three phenotypes of CTCs according on different epithelial-to-mesenchymal transition (EMT) markers, including epithelial, mesenchymal, and epithelial/mesenchymal (mixed phenotypic) CTCs. We intended to explore the relationship among CTC phenotypes and the clinicopathological characteristics of patients with differentiated thyroid carcinoma (DTC). Methods: Peripheral blood samples from 58 patients with DTC were collected, and CTCs were isolated by cell sizes. To identify phenotypes of CTCs, branched DNA signal amplification technology was adopted to capture and amplify target sequences, and then multiplex RNA-in situ hybridization (RNA-ISH) assay was used to identify CTC phenotypes depended on epithelial-mesenchymal transition (EMT) markers. Results: The positive rate of CTCs was 77.59% in 58 DTC patients. Totally, 488 CTCs with detective phenotype were found. Among them, there were 121 (24.80%) epithelial CTCs, 67 (13.72%) mesenchymal CTCs, and 300 (61.48%) mixed phenotypic CTCs. An obvious increased epithelial CTCs was observed in male patients compared with female. Notably, CTCs were more prevailing in younger male patients with ETI and bilateral focus. Conclusions: The CTCs are common in DTC patients, and mixed phenotypic is the major phenotype, indicating that EMT is prevalent in DTC even though its prognosis was better than other epithelial tumors. Detection of CTC and its phenotypes might independently predict the prognosis of DTC.

New horizons in the identification of circulating tumor cells (CTCs): An emerging paradigm shift in cytosensors

Circulating tumor cells (CTCs) are cancer cells that are shed from a primary tumor into the bloodstream and function as seeds for cancer metastasis at distant locations. Enrichment and identification methods of CTCs in the blood of patients plays an important role in diagnostic assessments and personalized treatments of cancer. However, the current traditional identification methods not only impact the viability of cells, but also cannot determine the type of cancer cells when the disease is unknown. Hence, new methods to identify CTCs are urgently needed. In this context, many advanced and safe technologies have emerged to distinguish between cancer cells and blood cells, and to distinguish specific types of cancer cells. In this review, at first we have briefly discussed recent advances in technologies related to the enrichment of CTCs, which lay a good foundation for the identification of CTCs. Next, we have summarized state-of-the-art technologies to confirm whether a given cell is indeed a tumor cell and determine the type of tumor cell. Finally, the challenges for application and potential directions of the current identification methods in clinical analysis of CTCs have been discussed.

MicroRNAs Involved in Small-cell Lung Cancer as Possible Agents for Treatment and Identification of New Targets

Small-cell lung cancer, a neuro-endocrine type of lung cancers, responds very well to chemotherapy-based agents. However, a high frequency of relapse due to adaptive resistance is observed. Immunotherapy-based treatments with checkpoint inhibitors has resulted in improvement of treatment but the responses are not as impressive as in other types of tumor. Therefore, identification of new targets and treatment modalities is an important issue. After searching the literature, we identified eight down-regulated microRNAs involved in radiation- and chemotherapy-induced resistance, as well as three up-regulated and four down-regulated miRNAs with impacts on proliferation, invasion and apoptosis of small-cell lung cancer cells in vitro. Furthermore, one up-regulated and four down-regulated microRNAs with in vivo activity in SCLC cell xenografts were identified. The identified microRNAs are candidates for inhibition or reconstitution therapy. The corresponding targets are candidates for inhibition or functional reconstitution with antibody-based moieties or small molecules.

Computational systems-biology approaches for modeling gene networks driving epithelial-mesenchymal transitions

Epithelial-mesenchymal transition (EMT) is an important biological process through which epithelial cells undergo phenotypic transitions to mesenchymal cells by losing cell-cell adhesion and gaining migratory properties that cells use in embryogenesis, wound healing, and cancer metastasis. An important research topic is to identify the underlying gene regulatory networks (GRNs) governing the decision making of EMT and develop predictive models based on the GRNs. The advent of recent genomic technology, such as single-cell RNA sequencing, has opened new opportunities to improve our understanding about the dynamical controls of EMT. In this article, we review three major types of computational and mathematical approaches and methods for inferring and modeling GRNs driving EMT. We emphasize (1) the bottom-up approaches, where GRNs are constructed through literature search; (2) the top-down approaches, where GRNs are derived from genome-wide sequencing data; (3) the combined top-down and bottom-up approaches, where EMT GRNs are constructed and simulated by integrating bioinformatics and mathematical modeling. We discuss the methodologies and applications of each approach and the available resources for these studies.

Glycyrrhizin ameliorates melanoma cell extravasation into mouse lungs by regulating signal transduction through HMGB1 and its receptors

Metastasis, which accounts for the majority of all cancer-related deaths, occurs through several steps, namely, local invasion, intravasation, transport, extravasation, and colonization. Glycyrrhizin has been reported to inhibit pulmonary metastasis in mice inoculated with B16 melanoma. This study aimed to identify the mechanism through which glycyrrhizin ameliorates the extravasation of melanoma cells into mouse lungs. Following B16 melanoma cell injection, mice were orally administered glycyrrhizin once every two days over 2 weeks; lung samples were then obtained and analyzed. Blood samples were collected on the final day, and cytokine plasma levels were determined. We found that glycyrrhizin ameliorated the extravasation of melanoma cells into the lungs and suppressed the plasma levels of interleukin-6, tumor necrosis factor-α, and transforming growth factor-β. Furthermore, glycyrrhizin ameliorated the lung tissue expression of high mobility group box-1 protein (HMGB1), receptor for advanced glycation end products (RAGE), Toll-like receptor (TLR)-4, RAS, extracellular signal-related kinase, NF-κB, myeloid differentiation primary response 88, IκB kinase complex, epithelial-mesenchymal transition markers, and vascular endothelial growth factor-A. Our study demonstrates that glycyrrhizin ameliorates melanoma metastasis by regulating the HMGB1/RAGE and HMGB1/TLR-4 signal transduction pathways.

Ovalitenone Inhibits the Migration of Lung Cancer Cells via the Suppression of AKT/mTOR and Epithelial-to-Mesenchymal Transition

Cancer metastasis is the major cause of about 90% of cancer deaths. As epithelial-to-mesenchymal transition (EMT) is known for potentiating metastasis, this study aimed to elucidate the effect of ovalitenone on the suppression of EMT and metastasis-related behaviors, including cell movement and growth under detached conditions, and cancer stem cells (CSCs), of lung cancer cells. Methods: Cell viability and cell proliferation were determined by 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazo-liumbromide (MTT) and colony formation assays. Cell migration and invasion were analyzed using a wound-healing assay and Boyden chamber assay, respectively. Anchorage-independent cell growth was determined. Cell protrusions (filopodia) were detected by phalloidin-rhodamine staining. Cancer stem cell phenotypes were assessed by spheroid formation. The proteins involved in cell migration and EMT were evaluated by Western blot analysis and immunofluorescence staining. Results: Ovalitenone was used at concentrations of 0–200 μM. While it caused no cytotoxic effects on lung cancer H460 and A549 cells, ovalitenone significantly suppressed anchorage-independent growth, CSC-like phenotypes, colony formation, and the ability of the cancer to migrate and invade cells. The anti-migration activity was confirmed by the reduction of filopodia in the cells treated with ovalitenone. Interestingly, we found that ovalitenone could significantly decrease the levels of N-cadherin, snail, and slug, while it increased E-cadherin, indicating EMT suppression. Additionally, the regulatory signaling of focal adhesion kinase (FAK), ATP-dependent tyrosine kinase (AKT), the mammalian target of rapamycin (mTOR), and cell division cycle 42 (Cdc42) was suppressed by ovalitenone. Conclusions: The results suggest that ovalitenone suppresses EMT via suppression of the AKT/mTOR signaling pathway. In addition, ovalitenone exhibited potential for the suppression of CSC phenotypes. These data reveal the anti-metastasis potential of the compound and support the development of ovalitenone treatment for lung cancer therapy.

Nondestructive quantification of single-cell nuclear and cytoplasmic mechanical properties based on large whole-cell deformation

The mechanical properties of cell nuclei have been recognized to reflect and modulate important cell behaviors such as migration and cancer cell malignant tendency. However, these nuclear properties are difficult to characterize accurately using conventional measurement methods, which are often based on probing or deforming local sites over a nuclear region. The corresponding results are sensitive to the measurement position, and they are not decoupled from the cytoplasmic properties. Microfluidics is widely recognized as a promising technique for bioassay and phenotyping. In this report, we develop a simple and nondestructive approach for the single-cell quantification of nuclear elasticity based on microfluidics by considering different deformation levels of a live cell captured along a confining microchannel. We apply two inlet pressure levels to drive the flow of human nasopharyngeal epithelial cells (NP460) and human nasopharyngeal cancerous cells (NPC43) into the microchannels. A model considering the essential intracellular components (cytoplasm and nucleus) for describing the mechanics of a cell deforming along the confining microchannel is used to back-calculate the cytoplasmic and nuclear properties. On the other hand, we also apply a widely used chemical nucleus extraction technique to examine its possible effects (e.g., reduced nuclear modulus and reduced lamin A/C expression). To determine if the decoupled nuclear properties are representative of cancer-related attributes, we classify the NP460 and NPC43 cells using the decoupled physical properties as classification factors, resulting in an accuracy of 79.1% and a cell-type specificity exceeding 74%. It should be mentioned that the cells can be recollected at the device outlet after the nondestructive measurement. Hence, the reported cell elasticity measurement can be combined with downstream genetic and biochemical assays for general cell research and cancer diagnostic applications.

Evaluation of sensitivity and specificity of CanPatrol™ technology for detection of circulating tumor cells in patients with non-small cell lung cancer

Background

The early diagnosis of non-small cell lung cancer is of great significance to the prognosis of patients. However, traditional histopathology and imaging screening have certain limitations. Therefore, new diagnostical methods are urgently needed for the current clinical diagnosis. In this study we evaluated the sensitivity and specificity of CanPatrol™ technology for the detection of circulating tumor cells in patients with non-small cell lung cancer (NSCLC).

Methods

CTCs in the peripheral blood of 98 patients with NSCLC and 38 patients with benign pulmonary diseases were collected by the latest typing of CanPatrol™ detection technology. A 3-year follow-up was performed to observe their recurrence and metastasis. Kruskal-Wallis test was used to compare multiple groups of data, Mann-Whitney U test was used to compare data between the two groups, and ROC curve analysis was used to obtain the critical value. The COX risk regression and Kaplan-Meier survival analysis were performed in the 63 NSCLC patients who were effectively followed up.

Results

The epithelial, epithelial-mesenchymal, and total CTCs were significantly higher in NSCLC patients than that in patients with benign lung disease (P <  0.001). The mesenchymal CTCs of NSCLC patients was slightly higher than that of benign lung diseases (P = 0.013). The AUC of the ROC curve of the total CTCs was 0.837 (95% CI: 0.76-0.914), and the cut-off value corresponding to the most approximate index was 0.5 CTCs/5 ml, at which point the sensitivity was 81.6% and the specificity was 86.8%. COX regression analysis revealed that the clinical stage was correlated with patient survival (P = 0.006), while gender, age, and smoking were not (P > 0.05). After excluding the confounders of staging, surgery, and chemotherapy, Kaplan-Meier survival analysis showed that patients in stage IIIA with CTCs ≥0.5 had significantly lower DFS than those with CTCs < 0.5 (P = 0.022).

Conclusions

CTC positive can well predict the recurrence of NSCLC patients. CanPatrol™ technology has good sensitivity and specificity in detecting CTCs in peripheral blood of NSCLC patients and has a certain value for clinical prognosis evaluation.

Supplementary information

Supplementary information accompanies this paper at 10.1186/s12890-020-01314-4.

Correlations between circulating tumor cell phenotyping and 18F-fluorodeoxyglucose positron emission tomography uptake in non-small cell lung cancer

PURPOSE

The epithelial-to-mesenchymal transition (EMT) phenotype-based subsets of circulating tumor cells (CTCs) might be predictors of tumor progression. We evaluated the clinical properties of different phenotypic CTCs in patients with non-small cell lung cancer (NSCLC). Secondly, we explored the association between different phenotypic CTCs and the uptake of 18F-fluorodeoxyglucose (FDG) by the primary tumor on a positron emission tomographic (PET) scan.

METHODS

Venous blood samples from 34 pathologically confirmed Stage IIB-IVB NSCLC patients were collected prospectively. CTCs were immunoassayed using a SE-i·FISH®CTC kit. We identified CTCs into cytokeratin positive (CK⁺) and cytokeratin negative (CK^-) phenotypes. CTC classifications were correlated with the maximum standardized uptake value (SUVmax) measured by 18F-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT). Overall survival (OS) and progression-free survival (PFS) curves were produced using the Kaplan-Meier method.

RESULTS

CTCs were detected in 91.2% of NSCLC patients. CTC counting was associated with TNM stage (P = 0.014) and distant metastasis (P = 0.007). The number of CK^-CTCs was also positively associated with TNM stage (P = 0.022) and distant metastasis (P = 0.007). Both total CTC counting and CK^-CTC counting did not show association with SUVmax value (P = 0.959, P = 0.903). Kaplan-Meier survival analysis demonstrated that patients with ≥ 7 CTCs had shorter OS (P = 0.003) and PFS (P = 0.001) relative to patients with < 7 CTCs). Notably, the number of CK^-CTCs can act as independent risk factors for PFS (P = 0.044) and OS (P = 0.043) in NSCLC patients. However, SUVmax value was not associated with OS (P = 0.895) and PFS (P = 0.686).

CONCLUSION

The CTC subpopulations could be useful evidence for testing metastasis and prognosis in NSCLC patients. The SUVmax value of the primary tumor was not related to prognosis in patients with NSCLC.

EMT-Associated Heterogeneity in Circulating Tumor Cells: Sticky Friends on the Road to Metastasis

Epithelial-mesenchymal transitions (EMTs) generate hybrid phenotypes with an enhanced ability to adapt to diverse microenvironments encountered during the metastatic spread. Accordingly, EMTs play a crucial role in the biology of circulating tumor cells (CTCs) and contribute to their heterogeneity. Here, we review major EMT-driven properties that may help hybrid Epithelial/Mesenchymal CTCs to survive in the bloodstream and accomplish early phases of metastatic colonization. We then discuss how interrogating EMT in CTCs as a companion biomarker could help refine cancer patient management, further supporting the relevance of CTCs in personalized medicine.

Microfluidic applications on circulating tumor cell isolation and biomimicking of cancer metastasis

The prognosis of malignant tumors is challenged by insufficient means to effectively detect tumors at early stage. Liquid biopsy using circulating tumor cells (CTCs) as biomarkers demonstrates a promising solution to tackle the challenge, because CTCs play a critical role in cancer metastatic process via intravasation, circulation, extravasation, and formation of secondary tumor. However, the effectiveness of the solution is compromised by rarity, heterogeneity, and vulnerability associated with CTCs. Among a plethora of novel approaches for CTC isolation and enrichment, microfluidics leads to isolation and detection of CTCs in a cost-effective and operation-friendly way. Development of microfluidics also makes it feasible to model the cancer metastasis in vitro using a microfluidic system to mimick the in vivo microenvironment, thereby enabling analysis and monitor of tumor metastasis. This paper aims to review the latest advances for exploring the dual-roles microfluidics has played in early cancer diagnosis via CTC isolation and investigating the role of CTCs in cancer metastasis; the merits and drawbacks for dominating microfluidics-based CTC isolation methods are discussed; biomimicking cancer metastasis using microfluidics are presented with example applications on modelling of tumor microenvironment, tumor cell dissemination, tumor migration, and tumor angiogenesis. The future perspectives and challenges are discussed.

Recent advances in gastric cancer early diagnosis

Gastric cancer (GC) remains an important cause of cancer death worldwide with a high mortality rate due to the fact that the majority of GC cases are diagnosed at an advanced stage when the prognosis is poor and the treatment options are limited. Unfortunately, the existing circulating biomarkers for GC diagnosis and prognosis display low sensitivity and specificity and the GC diagnosis is based only on the invasive procedures such as upper digestive endoscopy. There is a huge need for less invasive or non-invasive tests but also highly specific biomarkers in case of GC. Body fluids such as peripheral blood, urine or saliva, stomach wash/gastric juice could be a source of specific biomarkers, providing important data for screening and diagnosis in GC. This review summarized the recently discovered circulating molecules such as microRNAs, long non-coding RNAs, circular RNAs, which hold the promise to develop new strategies for early diagnosis of GC.

Circulating tumor cells as an independent prognostic factor in advanced colorectal cancer: a retrospective study in 121 patients

PURPOSE

This study aimed to evaluate the prognostic value of circulating tumor cells (CTCs) in advanced colorectal cancer (CRC) patients during chemotherapy course.

METHODS

From January 2016 to September 2017, the clinicopathological variables, such as gender, age, tumor location, tumor de-differentiation, depth of invasion, lymphatic invasion, distant metastasis, TNM stage, CTCs enumeration during 2-6 cycles of chemotherapy, and serum carcinoembryonic antigen (CEA) level during the same period, of 121 newly acquired and histopathologically confirmed CRC patients were collected from the Shanghai Ninth People's Hospital affiliated to Shanghai Jiao Tong University School of Medicine. All patients were followed up for survival until the end of November 2018. Statistical analysis focused on the associations between CTCs counts and clinicopathological variables. Overall survival (OS) and progression-free survival (PFS) among different prognostic factors were calculated using the Kaplan-Meier method, and the differences between the survival curves were compared by using the log-rank test. Factors of prognostic significance were investigated with the multivariate Cox regression analysis.

RESULTS

Here, 71 of 121 patients were CTC-positive, in which CTC-positive rate was positively correlated with the depth of invasion, lymphatic invasion, distant metastasis, TNM stage, and serum CEA level (P < 0.05 for all). However, no significant difference was found between CTC-positive and other clinicopathological variables (P > 0.05 for all), such as gender, age, tumor location, and tumor de-differentiation. CTCs counts gradually increased with the advancement of depth of invasion (P = 0.002), lymphatic invasion (P = 0.004), distant metastasis (P = 0.007), TNM stage (P = 0.001), serum CEA level (P = 0.001), and decreased tumor de-differentiation (P = 0.011). Furthermore, the Kaplan-Meier survival curves showed that patients with CTC-positive had a significantly unfavorable PFS (14 vs. 23 months, P = 0.001) and OS (18 vs. 25 months, P = 0.003). The multivariate Cox regression analyses revealed that the presence of CTCs during chemotherapy was an independent factor for unfavorable PFS (hazard ratio (HR) 2.682, P = 0.017, 95% confidence interval (CI) 1.193-6.029) and OS (HR 2.790, P = 0.048, 95% CI 1.010-7.705) in advanced CRC patients.

CONCLUSIONS

This study provided an evidence that the presence of CTCs may be valuable for predicting survival outcome, and CTCs was associated with unfavorable survival in advanced CRC patients during chemotherapy.

Molecular detection of epithelial-mesenchymal transition markers in circulating tumor cells from pancreatic cancer patients: Potential role in clinical practice

AIM

To evaluate the clinical properties of three subpopulations of circulating tumor cells (CTCs) undergoing epithelial-mesenchymal transition (EMT) in pancreatic ductal adenocarcinoma (PDAC) patients.

METHODS

We identified CTCs for expression of the epithelial cell marker cytokeratin or epithelial cell adhesion molecule (EpCAM) (E-CTC), the mesenchymal cell markers vimentin and twist (M-CTC), or both (E/M-CTC) using the CanPatrol system. Between July 2014 and July 2016, 107 patients with PDAC were enrolled for CTC evaluation. CTC enumeration and classification were correlated with patient clinicopathological features and outcomes.

RESULTS

CTCs were detected in 78.5% of PDAC patients. The number of total CTCs ranged from 0 to 26 across all 107 patients, with a median value of six. CTC status correlated with lymph node metastasis, TNM stage, distant metastasis, blood lymphocyte counts, and neutrophil-to-lymphocyte ratio (NLR). Kaplan-Meier survival analysis showed that patients with ≥ 6 total CTCs had significantly decreased overall survival and progression-free survival compared with patients with < 6 total CTCs. The presence of M-CTCs was positively correlated with TNM stage (P < 0.01) and distant metastasis (P < 0.01). Additionally, lymphocyte counts and NLR in patients without CTCs were significantly different from those in patients testing positive for each CTC subpopulation (P < 0.01).

CONCLUSION

Classifying CTCs by EMT markers helps to identify the more aggressive CTC subpopulations and provides useful evidence for determining a suitable clinical approach.

Circulating Tumor Cell Phenotype Indicates Poor Survival and Recurrence After Surgery for Hepatocellular Carcinoma

BACKGROUND

Circulating tumors cells (CTCs) may be a promising prognostic marker for patients with malignant tumors. However, there are few reports regarding its value for hepatocellular carcinoma (HCC) patients.

AIMS

To investigate CTCs with epithelial and mesenchymal phenotypes as a potential prognostic biomarker for HCC patients.

METHODS

Peripheral blood samples were obtained from 165 HCC patients before radical surgery. CTCs were isolated via the CanPatrol CTC enrichment technique and classified using epithelial-mesenchymal transition (EMT) markers. The relationship of CTC phenotype with clinicopathological factors and HCC recurrence in patients was analyzed.

RESULTS

CTC-positive status (count ≥ 2/5 mL) was found in 70.9% of the 165 HCC patients. Increased CTC number was more common in patients with higher AFP levels, multiple tumors, advanced TNM and BCLC staging, and presence of embolus or microembolus (P < 0.05). CTCs heterogeneity was noted using EMT markers. Mesenchymal CTCs were significantly correlated with high AFP levels, multiple tumors, advanced TNM and BCLC stage, presence of embolus or microembolus, and earlier recurrence (P < 0.05). The presence of mesenchymal CTCs predicted the shortest relapse-free survival, followed by mixed phenotypic CTCs, and then epithelial CTCs (P < 0.001).

CONCLUSION

CTC phenotype may serve as a prognostic indicator for HCC patients. CTCs assessment should include phenotypic identification tailored to characterize cells based on epithelial and mesenchymal markers.

Liquid Biopsy in Colorectal Cancer-Current Status and Potential Clinical Applications

Colorectal cancer is one of the most frequent solid malignancies worldwide. The treatment is either surgical or multimodal and depends on the stage of the disease at diagnosis. Accurate disease assessment is thus of great importance for choosing the most optimal treatment strategy. However, the standard means of disease assessment by radiological imaging or histopathological analysis of the removed tumor tissue lack the sensitivity in detecting the early systemic spread of the disease. To overcome this deficiency, the concept of liquid biopsy from the peripheral blood of patients has emerged as a new, very promising diagnostic tool. In this article, we provide an overview of the current status of clinical research on liquid biopsy in colorectal cancer. We also highlight the clinical situations in which the concept might be of the greatest benefit for the management of colorectal cancer patients in the future.

OSM potentiates preintravasation events, increases CTC counts, and promotes breast cancer metastasis to the lung

Background

Systemic and chronic inflammatory conditions in patients with breast cancer have been associated with reduced patient survival and increased breast cancer aggressiveness. This paper characterizes the role of an inflammatory cytokine, oncostatin M (OSM), in the preintravasation aspects of breast cancer metastasis.

Methods

OSM expression levels in human breast cancer tissue samples were assessed using tissue microarrays, and expression patterns based on clinical stage were assessed. To determine the in vivo role of OSM in breast cancer metastasis to the lung, we used three orthotopic breast cancer mouse models, including a syngeneic 4T1.2 mouse mammary cancer model, the MDA-MB-231 human breast cancer xenograft model, and an OSM-knockout (OSM-KO) mouse model. Progression of metastatic disease was tracked by magnetic resonance imaging and bioluminescence imaging. Endpoint analysis included circulating tumor cell (CTC) counts, lung metastatic burden analysis by qPCR, and ex vivo bioluminescence imaging.

Results

Using tissue microarrays, we found that tumor cell OSM was expressed at the highest levels in ductal carcinoma in situ. This finding suggests that OSM may function during the earlier steps of breast cancer metastasis. In mice bearing MDA-MB-231-Luc2 xenograft tumors, peritumoral injection of recombinant human OSM not only increased metastases to the lung and decreased survival but also increased CTC numbers. To our knowledge, this is the first time that a gp130 family inflammatory cytokine has been shown to directly affect CTC numbers. Using a 4T1.2 syngeneic mouse model of breast cancer, we found that mice bearing 4T1.2-shOSM tumors with knocked down tumor expression of OSM had reduced CTCs, decreased lung metastatic burden, and increased survival compared with mice bearing control tumors. CTC numbers were further reduced in OSM-KO mice bearing the same tumors, demonstrating the importance of both paracrine- and autocrine-produced OSM in this process. In vitro studies further supported the hypothesis that OSM promotes preintravasation aspects of cancer metastasis, because OSM induced both 4T1.2 tumor cell detachment and migration.

Conclusions

Collectively, our findings suggest that OSM plays a crucial role in the early steps of metastatic breast cancer progression, resulting in increased CTCs and lung metastases as well as reduced survival. Therefore, early therapeutic inhibition of OSM in patients with breast cancer may prevent breast cancer metastasis.

Electronic supplementary material

The online version of this article (10.1186/s13058-018-0971-5) contains supplementary material, which is available to authorized users.

Limited utility of tissue micro-arrays in detecting intra-tumoral heterogeneity in stem cell characteristics and tumor progression markers in breast cancer

Background

Intra-tumoral heterogeneity has been recently addressed in different types of cancer, including breast cancer. A concept describing the origin of intra-tumoral heterogeneity is the cancer stem-cell hypothesis, proposing the existence of cancer stem cells that can self-renew limitlessly and therefore lead to tumor progression. Clonal evolution in accumulated single cell genomic alterations is a further possible explanation in carcinogenesis. In this study, we addressed the question whether intra-tumoral heterogeneity can be reliably detected in tissue-micro-arrays in breast cancer by comparing expression levels of conventional predictive/prognostic tumor markers, tumor progression markers and stem cell markers between central and peripheral tumor areas.

Methods

We analyzed immunohistochemical expression and/or gene amplification status of conventional prognostic tumor markers (ER, PR, HER2, CK5/6), tumor progression markers (PTEN, PIK3CA, p53, Ki-67) and stem cell markers (mTOR, SOX2, SOX9, SOX10, SLUG, CD44, CD24, TWIST) in 372 tissue-micro-array samples from 72 breast cancer patients. Expression levels were compared between central and peripheral tumor tissue areas and were correlated to histopathological grading. 15 selected cases additionally underwent RNA sequencing for transcriptome analysis.

Results

No significant difference in any of the analyzed between central and peripheral tumor areas was seen with any of the analyzed methods/or results that showed difference. Except mTOR, PIK3CA and SOX9 (nuclear) protein expression, all markers correlated significantly (p < 0.05) with histopathological grading both in central and peripheral areas.

Conclusion

Our results suggest that intra-tumoral heterogeneity of stem-cell and tumor-progression markers cannot be reliably addressed in tissue-micro-array samples in breast cancer. However, most markers correlated strongly with histopathological grading confirming prognostic information as expression profiles were independent on the site of the biopsy was taken.

Electronic supplementary material

The online version of this article (10.1186/s12967-018-1495-6) contains supplementary material, which is available to authorized users.

EMT-like circulating tumor cells in ovarian cancer patients are enriched by platinum-based chemotherapy

Background

Assuming that tumor cell dissemination requires a shift to a mesenchymal phenotype, we analyzed the incidence of epithelial-to-mesenchymal-transition (EMT)-like circulating tumor cells (CTCs) in ovarian cancer patients and inquired, how their molecular phenotypes respond to platinum-based chemotherapy and influence outcome.

Results

Before surgery, overall detection rate for epithelial CTCs was 18%. EMT-like CTCs were more frequently observed (30%) and were mutually exclusive to epithelial CTCs in the majority of patients (82%). After chemotherapy, EMT-like CTCs increased up to 52%, accompanied by the “de novo” emergence of PI3Kα+/Twist+ EMT-like CTCs. Before surgery, PI3K+ EMT-like CTCs in combination with epithelial CTCs indicated decreased OS (p = 0.02) and FIGO I-III patients with residual tumor burden after surgery were more likely to be positive for EMT-like CTCs after chemotherapy (p = 0.02). In the latter group, epithelial CTCs alone significantly correlated with decreased PFS and OS (p = 0.02, p = 0.002), supported by an additional inclusion of PI3K+ CTCs (OS, p = 0.001).

Materials and Methods

Blood samples of 91 ovarian cancer patients before surgery and 31 matched samples after adjuvant chemotherapy were evaluated for CTCs with the AdnaTest ovarian cancer and EMT-1, analyzing the epithelial-associated transcripts EpCAM, Muc-1 and CA125 and the EMT-associated transcripts PI3Kα, Akt-2 and Twist.

Conclusions

Platinum-based chemotherapy seems to select for EMT-like CTCs in ovarian cancer patients and provokes a shift towards PI3Kα and Twist expressing CTCs, which may reflect clonal tumor evolution towards therapy resistance. It has to be determined, whether this CTC subgroup may serve as a biomarker to identify patients at high risk.

Liquid biopsy provides new insights into gastric cancer

Liquid biopsies have great promise for precision medicine as they provide information about primary and metastatic tumors via a minimally invasive method. In gastric cancer patients, a large number of blood-based biomarkers have been reported for their potential role in clinical practice for screening, early diagnosis, prognostic evaluation, recurrence monitoring and therapeutic efficiency follow-up. This current review focuses on blood liquid biopsies' role and their clinical implications in gastric cancer patients, with an emphasis on circulating tumor cells (CTCs), circulating tumor DNA (ctDNA) and circulating non-coding RNAs (ncRNAs). We also provide a brief discussion of the potential and limitations of liquid biopsies use and their future use in the routine clinical care of gastric cancer.

Expression and clinical relevance of epithelial and mesenchymal markers in circulating tumor cells from colorectal cancer

Circulating tumor cells (CTCs) with phenotypic hallmarks of epithelial-mesenchymal transition (EMT) reportedly contribute to tumor metastasis in different cancer types. We therefore evaluated the expression of EMT markers in CTCs obtained from a large cohort of Chinese patients with colorectal cancer (CRC) and investigated their clinical relevance. The CanPatrol^TM CTC enrichment technique was used to isolate and classify CTCs. CTCs were detected in 1046 of 1203 patients (86.9%), and three phenotypes were identified based on the expression of epithelial and mesenchymal markers: epithelial CTCs, biophenotypic (epithelial/mesenchymal) CTCs, and mesenchymal CTCs. Total CTC numbers positively correlated with both clinical stage and lymph node metastasis and distant metastasis. Furthermore, both biophenotypic and mesenchymal, but not epithelial, CTCs, correlated with the above parameters, suggesting CTCs displaying a mesenchymal phenotype denote more aggressive disease and metastatic potential. This is the first study to demonstrate a significant correlation between CTCs displaying a mesenchymal phenotype and both clinical stage and metastasis in a large cohort of patients with CRC. Our findings suggest that assessment of not only epithelial, but also mesenchymal markers in CTC analyses may offer valuable assistance for tumor staging and metastasis evaluation in patients with CRC.

Associations between the Epithelial-Mesenchymal Transition Phenotypes of Circulating Tumor Cells and the Clinicopathological Features of Patients with Colorectal Cancer

In this study, we identified CTCs using the previously reported CanPatrol CTC enrichment technique from peripheral blood samples of 126 patients with colorectal cancer (CRC) and found that CTCs could be classified into three subpopulations based on expression of epithelial cell adhesion molecule (EpCAM) (E-CTCs), the mesenchymal cell marker vimentin (M-CTCs), or both EpCAM and vimentin (biphenotypic E/M-CTCs). Circulating tumor microemboli (CTMs) were also identified in peripheral blood samples. Meanwhile, E-CTCs, M-CTCs, E/M-CTCs, and CTMs were detected in 76.98%, 42.06%, 56.35%, and 36.51% of the 126 patients, respectively. Interestingly, the presence of CTMs and each CTC subpopulation was significantly associated with blood lymphocyte counts and tumor-node-metastasis stage (P < 0.001). Lymphocyte counts and the neutrophil-to-lymphocyte ratio (NLR) in patients lacking CTCs were significantly different from those in patients testing positive for CTMs and each CTC subpopulation (P < 0.001). Our results indicate that tumor metastasis is more significantly associated with the presence of CTMs and M-CTCs than with other CTC subpopulations and suggest that EMT may be involved in CTC evasion of lymphocyte-mediated clearance.

EMT: Mechanisms and therapeutic implications

Metastasis, the dissemination of cancer cells from primary tumors, represents a major hurdle in the treatment of cancer. The epithelial-mesenchymal transition (EMT) has been studied in normal mammalian development for decades, and it has been proposed as a critical mechanism during cancer progression and metastasis. EMT is tightly regulated by several internal and external cues that orchestrate the shifting from an epithelial-like phenotype into a mesenchymal phenotype, relying on a delicate balance between these two stages to promote metastatic development. EMT is thought to be induced in a subset of metastatic cancer stem cells (MCSCs), bestowing this population with the ability to spread throughout the body and contributing to therapy resistance. The EMT pathway is of increasing interest as a novel therapeutic avenue in the treatment of cancer, and could be targeted to prevent tumor cell dissemination in early stage patients or to eradicate existing metastatic cells in advanced stages. In this review, we describe the sequence of events and defining mechanisms that take place during EMT, and how these interactions drive cancer cell progression into metastasis. We summarize clinical interventions focused on targeting various aspects of EMT and their contribution to preventing cancer dissemination.

Blocking epithelial-to-mesenchymal transition in glioblastoma with a sextet of repurposed drugs: the EIS regimen

This paper outlines a treatment protocol to run alongside of standard current treatment of glioblastoma- resection, temozolomide and radiation. The epithelial to mesenchymal transition (EMT) inhibiting sextet, EIS Regimen, uses the ancillary attributes of six older medicines to impede EMT during glioblastoma. EMT is an actively motile, therapy-resisting, low proliferation, transient state that is an integral feature of cancers’ lethality generally and of glioblastoma specifically. It is believed to be during the EMT state that glioblastoma’s centrifugal migration occurs. EMT is also a feature of untreated glioblastoma but is enhanced by chemotherapy, by radiation and by surgical trauma. EIS Regimen uses the antifungal drug itraconazole to block Hedgehog signaling, the antidiabetes drug metformin to block AMP kinase (AMPK), the analgesic drug naproxen to block Rac1, the anti-fibrosis drug pirfenidone to block transforming growth factor-beta (TGF-beta), the psychiatric drug quetiapine to block receptor activator NFkB ligand (RANKL) and the antibiotic rifampin to block Wnt- all by their previously established ancillary attributes. All these systems have been identified as triggers of EMT and worthy targets to inhibit. The EIS Regimen drugs have a good safety profile when used individually. They are not expected to have any new side effects when combined. Further studies of the EIS Regimen are needed.

Epithelial-mesenchymal plasticity and circulating tumor cells: Travel companions to metastases

Epithelial-mesenchymal transitions (EMTs) associated with metastatic progression may contribute to the generation of hybrid phenotypes capable of plasticity. This cellular plasticity would provide tumor cells with an increased potential to adapt to the different microenvironments encountered during metastatic spread. Understanding how EMT may functionally equip circulating tumor cells (CTCs) with an enhanced competence to survive in the bloodstream and niche in the colonized organs has thus become a major cancer research axis. We summarize here clinical data with CTC endpoints involving EMT. We then review the work functionally linking EMT programs to CTC biology and deciphering molecular EMT-driven mechanisms supporting their metastatic competence. Developmental Dynamics 247:432-450, 2018. © 2017 Wiley Periodicals, Inc.

Thrombin-unique coagulation system protein with multifaceted impacts on cancer and metastasis

The association between blood coagulation and cancer development is well recognized. Thrombin, the pleiotropic enzyme best known for its contribution to fibrin formation and platelet aggregation during vascular hemostasis, may also trigger cellular events through protease-activated receptors, PAR-1 and PAR-4, leading to cancer progression. Our pioneering findings provided evidence that thrombin contributes to cancer metastasis by increasing adhesive potential of malignant cells. However, there is evidence that thrombin regulates every step of cancer dissemination: (1) cancer cell invasion, detachment from primary tumor, migration; (2) entering the blood vessel; (3) surviving in vasculature; (4) extravasation; (5) implantation in host organs. Recent studies have provided new molecular data about thrombin generation in cancer patients and the mechanisms by which thrombin contributes to transendothelial migration, platelet/tumor cell interactions, angiogenesis, and other processes. Though a great deal is known regarding the role of thrombin in cancer dissemination, there are new data for multiple thrombin-mediated events that justify devoting focus to this topic with a comprehensive approach.

Microfluidic chip for isolation of viable circulating tumor cells of hepatocellular carcinoma for their culture and drug sensitivity assay

Circulating tumor cells (CTCs) have been proposed to be an active source of metastasis or recurrence of hepatocellular carcinoma (HCC). The enumeration and characterization of CTCs has important clinical significance in recurrence prediction and treatment monitoring in HCC patients. We previously developed a unique method to separate HCC CTCs based on the interaction of the asialoglycoprotein receptor (ASGPR) expressed on their membranes with its ligand. The current study applied the ligand-receptor binding assay to a CTC-chip in a microfluidic device. Efficient capture of HCC CTCs originates from the small dimensions of microfluidic channels and enhanced local topographic interactions between the microfluidic channel and extracellular extensions. With the optimized conditions, a capture yield reached > 85% for artificial CTC blood samples. Clinical utility of the system was further validated. CTCs were detected in all the examined 36 patients with HCC, with an average of 14 ± 10/2 mL. On the contrary, no CTCs were detected in healthy, benign liver disease or non-HCC cancer subjects. The current study also successfully demonstrated that the captured CTCs on our CTC-chip were readily released with ethylene diamine tetraacetic acid (EDTA); released CTCs remained alive and could be expanded to form a spheroid-like structure in a 3-dimensional cell culture assay; furthermore, sensitivity of released CTCs to chemotherapeutic agents (sorafenib or oxaliplatin) could be effectively tested utilizing this culture assay. In conclusion, the methodologies presented here offer great promise for accurate enumeration and easy release of captured CTCs, and released CTCs could be cultured for further functional studies.

FGFs: crucial factors that regulate tumour initiation and progression

Fibroblast growth factors (FGFs) are crucial signalling molecules involved in normal cell growth, differentiation and proliferation. Over the past few decades, a large body of research has illustrated effects of individual FGFs on tumour initiation and progression. Tumour development is commonly accompanied with generation of new blood and lymph vessels, which support enhanced cell proliferation. Moreover, acquisition of tumour cells of the epithelial-mesenchymal transition (EMT) phenotype, enhances tumour cell migration and invasion potentials, crucial steps in tumour metastasis. This review summarizes recent findings concerning roles of FGFs in angiogenesis, lymphangiogenesis and EMT.

Salvianolic acid A reverses the paclitaxel resistance and inhibits the migration and invasion abilities of human breast cancer cells by inactivating transgelin 2

Multidrug resistance and tumor migration and invasion are the major obstacles to effective breast cancer chemotherapy, but the underlying molecular mechanisms remain unclear. This study investigated the potential of transgelin 2 and salvianolic acid A to modulate the resistance and the migration and invasion abilities of paclitaxel-resistant human breast cancer cells (MCF-7/PTX). MCF-7/PTX cells were found to exhibit not only a high degree of resistance to paclitaxel, but also strong migration and invasion abilities. Small interfering RNA-mediated knockdown of TAGLN2 sensitized the MCF-7/PTX cells to paclitaxel, and inhibited their migration and invasion abilities. In addition, we also observed that combined salvianolic acid A and paclitaxel treatment could reverse paclitaxel resistance, markedly inhibit tumor migration and invasion, and suppress the expression of transgelin 2 in MCF-7/PTX cells. These findings indicate that salvianolic acid A can reverse the paclitaxel resistance and inhibit the migration and invasion abilities of human breast cancer cells by down-regulating the expression of transgelin 2, and hence could be useful in breast cancer treatments.

Potential role of nuclear PD-L1 expression in cell-surface vimentin positive circulating tumor cells as a prognostic marker in cancer patients

Although circulating tumor cells (CTCs) have potential as diagnostic biomarkers for cancer, determining their prognostic role in cancer patients undergoing treatment is a challenge. We evaluated the prognostic value of programmed death-ligand 1 (PD-L1) expression in CTCs in colorectal and prostate cancer patients undergoing treatment. Peripheral blood samples were collected from 62 metastatic colorectal cancer patients and 30 metastatic prostate cancer patients. CTCs were isolated from the samples using magnetic separation with the cell-surface vimentin(CSV)-specific 84-1 monoclonal antibody that detects epithelial-mesenchymal transitioned (EMT) CTCs. CTCs were enumerated and analyzed for PD-L1 expression using confocal microscopy. PD-L1 expression was detectable in CTCs and was localized in the membrane and/or cytoplasm and nucleus. CTC detection alone was not associated with poor progression-free or overall survival in colorectal cancer or prostate cancer patients, but nuclear PD-L1 (nPD-L1) expression in these patients was significantly associated with short survival durations. These results demonstrated that nPD-L1 has potential as a clinically relevant prognostic biomarker for colorectal and prostate cancer. Our data thus suggested that use of CTC-based models of cancer for risk assessment can improve the standard cancer staging criteria and supported the incorporation of nPD-L1 expression detection in CTCs detection in such models.

Eukaryotic translation initiation factor 5A2 regulates the migration and invasion of hepatocellular carcinoma cells via pathways involving reactive oxygen species

Eukaryotic translation initiation factor 5A2 (eIF5A2) has been identified as a critical gene in tumor metastasis. Research has suggested that reactive oxygen species (ROS) serve as signaling molecules in cancer cell proliferation and migration. However, the mechanisms linking eIF5A2 and ROS are not fully understood. Here, we investigated the effects of ROS on the eIF5A2-induced epithelial-mesenchymal transition (EMT) and migration in six hepatocellular carcinoma (HCC) cell lines. Western hybridization, siRNA transfection, transwell migration assays, wound-healing assays, and immunofluorescence analysis were used. The protein levels of eIF5A2 in tumor and adjacent tissue samples from 90 HCC patients with detailed clinical, pathological, and clinical follow-up data were evaluated. Overexpression of eIF5A2 was found in cancerous tissues compared with adjacent tissues. We found that eIF5A2 overexpression in HCC was associated with reduced overall survival. Knockdown of eIF5A2 and intracellular reduction of ROS significantly suppressed the invasion and metastasis of HCC cells. Interestingly, N1-guanyl-1, 7-diaminoheptane (GC7) suppressed the intracellular ROS levels. After blocking the EMT, administration of GC7 or N-acetyl-L-cysteine did not reduce cell migration further. Based on the experimental data, we concluded that inhibition of eIF5A2 alters progression of the EMT to decrease the invasion and metastasis of HCC cells via ROS-related pathways.

Circulating tumor cell technologies†

Circulating tumor cells, a component of the “liquid biopsy”, hold great potential to transform the current landscape of cancer therapy. A key challenge to unlocking the clinical utility of CTCs lies in the ability to detect and isolate these rare cells using methods amenable to downstream characterization and other applications. In this review, we will provide an overview of current technologies used to detect and capture CTCs with brief insights into the workings of individual technologies. We focus on the strategies employed by different platforms and discuss the advantages of each. As our understanding of CTC biology matures, CTC technologies will need to evolve, and we discuss some of the present challenges facing the field in light of recent data encompassing epithelial‐to‐mesenchymal transition, tumor‐initiating cells, and CTC clusters.

We present a comprehensive overview of CTC detection and capture technologies.

We provide a conceptual description of strategies used in different technologies.

We highlight the key features of individual technologies.

We discuss CTC technology performance in the context of clinical studies.

Tumour budding in colorectal cancer: what do we know and what can we do?

Budding is a process during which individual or small clusters of up to five tumour cells detach from the main tumour mass and invade into the surrounding stroma. In colorectal cancer, this feature is observed in 20-40% of cases and is associated with lymphovascular invasion, lymph node and distant metastases, and poor prognosis. A variety of scoring systems for budding have been proposed but so far a gold standard is lacking, hampering implementation of a budding score in guidelines for pathological examination of colorectal cancer. Furthermore, little is known about the mechanisms which cause tumour cells to detach from the main tumour mass and obtain increased invasive potential. In this review, we present an overview of tumour budding including its definition, scoring systems, prognostic relevance and biological mechanisms involved.

Circulating tumor cells isolation: the "post-EpCAM era"

Circulating tumor cells (CTCs) represent a submicroscopic fraction detached from a primary tumor and in transit to a secondary site. The prognostic significance of CTCs in metastatic cancer patients was demonstrated for the first time more than ten years ago. To date, it seems clear enough that CTCs are highly heterogeneous and dynamically change their shape. Thus, the inadequacy of epithelial cell adhesion molecule (EpCAM) as universal marker for CTCs detection seems unquestionable and alternative methods able to recognize a broader spectrum of phenotypes are definitely needed. In this review the pleiotropic functions of EpCAM are discussed in detail and the role of the molecule in the biology of CTCs is critically dissected.

3D Silicon Microstructures: A New Tool for Evaluating Biological Aggressiveness of Tumor Cells

In this work, silicon micromachined structures (SMS), consisting of arrays of 3- μ m-thick silicon walls separated by 50- μm-deep, 5- μ m-wide gaps, were applied to investigate the behavior of eight tumor cell lines, with different origins and biological aggressiveness, in a three-dimensional (3D) microenvironment. Several cell culture experiments were performed on 3D-SMS and cells grown on silicon were stained for fluorescence microscopy analyses. Most of the tumor cell lines recognized in the literature as highly aggressive (OVCAR-5, A375, MDA-MB-231, and RPMI-7951) exhibited a great ability to enter and colonize the narrow deep gaps of the SMS, whereas less aggressive cell lines (OVCAR-3, Capan-1, MCF7, and NCI-H2126) demonstrated less penetration capability and tended to remain on top of the SMS. Quantitative image analyses of several fluorescence microscopy fields of silicon samples were performed for automatic cell recognition and count, in order to quantify the fraction of cells inside the gaps, with respect to the total number of cells in the examined field. Our results show that higher fractions of cells in the gaps are obtained with more aggressive cell lines, thus supporting in a quantitative way the observation that the behavior of tumor cells on the 3D-SMS depends on their aggressiveness level.

Circulating tumor cells in breast cancer beyond the genotype of primary tumor for tailored therapy

Although TNM staging based on tumor, node lymph status and metastasis status-is the most widely used method in the clinic to classify breast cancer (BC) and assess prognosis, it offers limited information for different BC subgroups. Circulating tumor cells (CTCs) are regarded as minimal residual disease and are proven to have a strong relationship with BC. Detection of ≥5 CTCs per 7.5 mL in peripheral blood predicts poor prognosis in metastatic BC irrespective of other clinical parameters, whereas, in early-stage BC, detection of CK19(+) CTCs are also associated with poor prognosis. Increasing data and clinical trials show that CTCs can improve prognostic accuracy and help tailor treatment for patients with BC. However, heterogeneous CTCs in the process of an epithelial-mesenchymal transition (EMT) in BC makes it a challenge to detect these rare cells. Moreover, the genotypic and phenotypic features of CTCs are different from primary BC tumors. Molecular analysis of CTCs in BC may benefit patients by identifying those amenable to tailored therapy. We propose that CTCs should be used alongside the TNM staging system and the genotype of primary tumor to guide tailored BC diagnosis and treatment.

Cellular Plasticity in Prostate Cancer Bone Metastasis

Purpose. Experimental data suggest that tumour cells can reversibly transition between epithelial and mesenchymal states (EMT and MET), a phenomenon known as cellular plasticity. The aim of this review was to appraise the clinical evidence for the role of cellular plasticity in prostate cancer (PC) bone metastasis. Methods. An electronic search was performed using PubMed for studies that have examined the differential expression of epithelial, mesenchymal, and stem cell markers in human PC bone metastasis tissues. Results. The review included nineteen studies. More than 60% of the studies used ≤20 bone metastasis samples, and there were several sources of heterogeneity between studies. Overall, most stem cell markers analysed, except for CXCR4, were positively expressed in bone metastasis tissues, while the expression of EMT and MET markers was heterogeneous between and within samples. Several EMT and stemness markers that are involved in osteomimicry, such as Notch, Met receptor, and Wnt/β pathway, were highly expressed in bone metastases. Conclusions. Clinical findings support the role of cellular plasticity in PC bone metastasis and suggest that epithelial and mesenchymal states cannot be taken in isolation when targeting PC bone metastasis. The paper also highlights several challenges in the clinical detection of cellular plasticity.

Differential Expression of ADAM23, CDKN2A (P16), MMP14 and VIM Associated with Giant Cell Tumor of Bone

Though benign, giant cell tumor of bone (GCTB) can become aggressive and can exhibit a high mitotic rate, necrosis and rarely vascular invasion and metastasis. GCTB has unique histologic characteristics, a high rate of multinucleated cells, a variable and unpredictable growth potential and uncertain biological behavior. In this study, we sought to identify genes differentially expressed in GCTB, thus building a molecular profile of this tumor. We performed quantitative real-time polymerase chain reaction (qPCR), immunohistochemistry and analyses of methylation to identify genes that are putatively associated with GCTB. The expression of the ADAM23 and CDKN2A genes was decreased in GCTB samples compared to normal bone tissue, measured by qPCR. Additionally, a high hypermethylation frequency of the promoter regions of ADAM23 and CDKN2A in GCTB was observed. The expression of the MAP2K3, MMP14, TIMP2 and VIM genes was significantly higher in GCTB than in normal bone tissue, a fact that was confirmed by qPCR and immunohistochemistry. The set of genes identified here furthers our understanding of the molecular basis of GCTB.

Improved method increases sensitivity for circulating hepatocellular carcinoma cells

AIM: To improve an asialoglycoprotein receptor (ASGPR)-based enrichment method for detection of circulating tumor cells (CTCs) of hepatocellular carcinoma (HCC).

METHODS: Peripheral blood samples were collected from healthy subjects, patients with HCC or various other cancers, and patients with hepatic lesions or hepatitis. CTCs were enriched from whole blood by extracting CD45-expressing leukocytes with monoclonal antibody coated-beads following density gradient centrifugation. The remaining cells were cytocentrifuged on polylysine-coated slides. Isolated cells were treated by triple immunofluorescence staining with CD45 antibody and a combination of antibodies against ASGPR and carbamoyl phosphate synthetase 1 (CPS1), used as liver-specific markers, and costained with DAPI. The cell slide was imaged and stained tumor cells that met preset criteria were counted. Recovery, sensitivity and specificity of the detection methods were determined and compared by spiking experiments with various types of cultured human tumor cell lines. Expression of ASGPR and CPS1 in cultured tumor cells and tumor tissue specimens was analyzed by flow cytometry and triple immunofluorescence staining, respectively.

RESULTS: CD45 depletion of leukocytes resulted in a significantly greater recovery of multiple amounts of spiked HCC cells than the ASGPR⁺ selection (Ps < 0.05). The expression rates of either ASGPR or CPS1 were different in various liver cancer cell lines, ranging between 18% and 99% for ASGPR and between 9% and 98% for CPS1. In both human HCC tissues and liver cancer cell lines, there were a few HCC cells that did not stain positive for ASGPR or CPS1. The mixture of monoclonal antibodies against ASGPR and CPS1 identified more HCC cells than either antibody alone. However, these antibodies did not detect any tumor cells in blood samples spiked with the human breast cancer cell line MCF-7 and the human renal cancer cell line A498. ASGPR⁺ or/and CPS1⁺ CTCs were detected in 29/32 (91%) patients with HCC, but not in patients with any other kind of cancer or any of the other test subjects. Furthermore, the improved method detected a higher CTC count in all patients examined than did the previous method (P = 0.001), and consistently achieved 12%-21% higher sensitivity of CTC detection in all seven HCC patients with more than 40 CTCs.

CONCLUSION: Negative depletion enrichment combined with identification using a mixture of antibodies against ASGPR and CPS1 improves sensitivity and specificity for detecting circulating HCC cells.

Circulating tumor cells versus objective response assessment predicting survival in metastatic castration-resistant prostate cancer patients treated with docetaxel chemotherapy

PURPOSE

Circulating tumor cell (CTC) counts might display a superior prognostic value for overall survival (OS) compared to objective response criteria (OR) in metastatic castration-resistant prostate cancer (mCRPC) patients.

METHODS

CTCs were detected using the CellSearch™ System out of 122 samples during docetaxel chemotherapy (75 mg/m(2)) at baseline (q0) and after 1 (q1), 4 (q4) and 10 (q10) cycles, in mCRPC patients (n = 33). OR was evaluated by morphologic RECIST and clinical criteria after 4 (q4) and 10 (q10) cycles.

RESULTS

For OS, analyses revealed a significant prognostic value for categorical (<5 vs. ≥5) CTC counts (q0, p = 0.005; q1, p = 0.001; q4, p < 0.001; q10, p = 0.002), RECIST (q4, p < 0.001; q10, p = 0.02) and clinical criteria (q4, p < 0.001; q10, p = 0.02). Concordance of CTC counts with OR revealed a sensitivity of 83.3-87.5 % and a specificity of 68.0-76.5 % with complementary discriminatory power for OS. Comparing CTC counts with concomitant OR at q4 in multivariate analyses, an independent prognostic value for OS was found for CTC counts (HR 3.3; p = 0.02) similar to clinical (HR 4.9; p = 0.02) and radiologic response (HR 3.4; p = 0.051). Comparing the predictive value for death, early post-treatment CTC counts at q1 demonstrated significant accuracy with an area under the curve of 79.5 % (p = 0.004) similar to CTC counts at q4 (76.7 %; p = 0.009). Radiologic and clinical response at q4 displayed accuracy similar to early CTC counts at q1 (72.2 %; p = 0.03 and 75.0 %; p = 0.02) despite low sensitivities.

CONCLUSIONS

CTC counts appear to be an earlier and more sensitive predictor for survival and treatment response than current OR approaches and may provide complementary information toward individualized treatment strategies.