UNASSIGNED: The characterization of circulating tumor cells (CTC) and circulating tumor microemboli (CTM) has emerged as both a challenge to the standard view of metastasis, and as a valuable means for understanding genotypic and phenotypic variability shown even within the same cancer type. However, in the case of salivary gland neoplasms, limited data are available for the role that CTCs and CTMs play in metastasis and secondary tumor formation.ru.AQ1 In response to this, we propose that similarities between in vitro clusters of cultured salivary gland cancer cells may act as a surrogate model for in vivo CTCs and CTMs isolated from patients.
UNASSIGNED: Using techniques in immunofluorescence, immunoblotting, and 2-dimensional migration, we isolated and characterized a group of cohort cells from a commercially available cell line (HTB-41). Results: Here, cells exhibited a hybrid phenotype with simultaneous expression of both epithelial and mesenchymal markers (E-cadherin, vimentin, and α-SMA). Cohort cells also exhibited increased migration in comparison to parental cells.
UNASSIGNED: Data suggest that these isolated cell clusters may fucntion as a potential in vitro model of CTCs and CTMs.

OBJECTIVE: Circulating tumor cell (CTC) detection is a promising noninvasive technique that can be used to diagnose cancer, monitor progression, and predict prognosis. In this study, the authors aimed to investigate the clinical utility of CTCs in the management of diffuse glioma.
METHODS: Sixty-three patients with newly diagnosed diffuse glioma were included in this multicenter clinical cohort. The authors used a platform based on isolation by size of epithelial tumor cells (ISET) to detect and analyze CTCs and circulating tumor microemboli (CTMs) in the peripheral blood of patients both before and after surgery. Least absolute shrinkage and selector operation (LASSO) and Cox regression analyses were used to verify whether CTCs and CTMs are independent prognostic factors for diffuse glioma.
RESULTS: CTC levels were closely related to the degree of malignancy, WHO grade, and pathological subtypes. Receiver operating characteristic curve analysis revealed that a high CTC level was a predictor for glioblastoma. The results also showed that CTMs originate from the parental tumor rather than from the circulation and are an independent prognostic factor for diffuse glioma. The postoperative CTC level is related to the peripheral immune system and patient survival. Cox regression analysis showed that postoperative CTC levels and CTM status are independent prognostic factors for diffuse glioma, and CTC- and CTM-based survival models had high accuracy in internal validation.
CONCLUSIONS: The authors revealed a correlation between CTCs and clinical characteristics and demonstrated that CTCs and CTMs are independent predictors for the diagnosis and prognosis of diffuse glioma. Their CTC- and CTM-based survival models can enable clinicians to evaluate patients\' response to surgery as well as their outcomes.

Circulating tumor cells (CTCs) and/or circulating tumor microemboli (CTM) from non-small cell lung cancer (NSCLC) patients may be a non-invasive tool for prognosis, acting as liquid biopsy. CTCs interact with platelets through the transforming growth factor-β/transforming growth factor-β receptor type 1 (TGF-β/TGFβRI) forming clusters. CTCs also may express the Cluster of Differentiation 47 (CD47) protein, responsible for the inhibition of phagocytosis, the \"don\'t eat me\" signal to macrophages.
OBJECTIVE: To isolate, quantify and analyze CTCs/CTMs from metastatic NSCLC patients, identify TGFβRI/CD47 expression in CTCs/CTMs, and correlate with progression-free survival (PFS).
METHODS: Blood (10 mL) was collected at two time-points: T1 (before the beginning of any line of treatment; T2 (60 days after initial collection). CTCs were isolated using ISET®. Immunocytochemistry was conducted to evaluate TGFβRI/CD47 expression.
RESULTS: 45 patients were evaluated. CTCs were observed in 82.2% of patients at T1 (median: 1 CTC/mL; range: 0.33-11.33 CTCs/mL) and 94.5% at T2 (median: 1.33 CTC/mL; 0.33-9.67). CTMs were observed in 24.5% of patients and significantly associated with poor PFS (10 months vs. 17 months for those without clusters; p = 0.05) and disease progression (p = 0.017). CTMs CD47+ resulted in poor PFS (p = 0.041). TGFβRI expression in CTCs/CTMs was not associated with PFS.
CONCLUSIONS: In this study, we observed that CTC/CTM from NSCLC patients express the immune evasion markers TGFβRI/CD47. The presence of CTMs CD47+ is associated with poor PFS. This was the first study to investigate CD47 expression in CTCs/CTM of patients with NSCLC and its association with poor PFS.

A 77-year-old man was admitted at our hospital due to \"generalized increase in the number of masses and enlargement of the masses observed for one month\". Combined assessment of the imaging (computed tomography and magnetic resonance imaging) findings and results of lung centesis biopsy and liquid biopsy suggest that the patient had small cell lung cancer of the left upper lobe, with right hilar, mediastinal, bilateral axillary, abdominal and retroperitoneal lymph node metastases, as well as widespread subcutaneous soft tissue, liver, bilateral adrenal, bilateral kidneys and multiple brain metastases (extensive stage). In order to obtain an evaluation of the development of the disease as soon as possible, the circulating tumor cells (CTCs) and circulating tumor microemboli (CTM) in 6 mL peripheral blood were examined by subtraction enrichment-immunostaining fluorescence in situ hybridization (SE-iFISH) technology. A total of 919 epithelial cell adhesion molecule (EpCAM)-positive CTCs and 61 EpCAM-positive CTM were identified. Among them, there were 14 haploid CTCs (1.52%), 788 diploid CTCs (85.75%), 44 triploid CTCs (4.79%), 70 tetraploid CTCs (7.62%) and 3 pentaploid or higher-fold polyploid CTCs (0.33%). Herein, we reported a rare case with extremely high accounts of CTCs and CTM and positive findings for tumor markers, which was identified for the first time. The examination of CTCs by SE-iFISH contributed to the diagnosis, prognosis and treatment evaluation of cancer and facilitated the formulation of precise and individualized therapeutic regime.

BACKGROUND: This study compared whole blood dilution versus density gradient centrifugation for pre-processing blood samples prior to circulating tumor cell (CTC) capture on the efficiency of CTC separation by size-based isolation.
METHODS: Whole blood from a healthy volunteer spiked with SKBR3 cells was used to optimize the whole blood dilution protocol for sample volume, dilution ratio, and paraformaldehyde (PFA) concentration. Whole blood from healthy volunteers spiked with SKBR3, A549, or PC3 cells, and whole blood from patients with advanced gastric, esophageal, or liver cancer, was used to compare pre-processing by the optimal whole blood dilution protocol with density-gradient centrifugation. All statistical evaluations were performed using Student t test of the Statistical Package for Social Sciences (SPSS version 17.0).
RESULTS: In blood samples from healthy volunteers, spiked SKBR3 cell recovery rates were highest in 5 ml of whole blood, diluted with 2.5 ml buffer, and fixed with 0.2% PFA, and spiked SKBR3, A549, and PC3 cell recovery rates from 5 ml whole blood were significantly greater when using the optimized whole blood dilution protocol (87.67% ± 1.76%, 79.50% ± 0.50% and 71.83% ± 1.04%, respectively) compared to density-gradient centrifugation (46.83 ± 1.76%, 37.00 ± 1.50% and 41.00 ± 1.50%, respectively).

Tumor metastasis is directly correlated to poor prognosis and high mortality. Circulating tumor cells (CTCs) play a pivotal role in metastatic cascades, of which CTC clusters is highly metastatic compared to single CTCs. Although platelets and neutrophils within the bloodstream could further exacerbate the pro-metastatic effect of single CTCs, the influence of platelets and neutrophils on CTC clusters mediated metastasis remains unclear. In this study, a pro-metastatic complex composed of CTC clusters, platelets and neutrophils, namely circulating tumor microemboli (CTM), was identified in vivo among different metastatic tumor, which was demonstrated with highly upregulation of hypoxia-inducible factor-1α (HIF-1α). While knock-out of HIF-1α or therapeutically downregulating of HIF-1α via HIF-1α inhibitor (BAY87-2243)-loaded neutrophil cyto-pharmaceuticals (PNEs) could efficiently restrain CTM mediated lung metastasis. The underlying mechanism of metastasis inhibition was attributed to the downregulation of HIF-1α-associated PD-L1, which would enhance immune response for inhibiting metastatic cells. Thus, our work here illustrates that hypoxia was an essential factor in promoting CTM colonization in lung. More importantly, we provide a promising strategy by targeted downregulation of HIF-1α in CTM via neutrophil cyto-pharmaceuticals for treatment of CTM mediated metastasis.

Circulating tumor cells (CTCs) have been recognized as a major contributor to distant metastasis. Their unique role as metastatic seeds renders them a potential marker in the circulation for early cancer diagnosis and prognosis as well as monitoring of therapeutic response. In the past decade, researchers mainly focused on the development of isolation techniques for improving the recovery rate and purity of CTCs. These developed techniques have significantly increased the detection sensitivity and enumeration accuracy of CTCs. Currently, significant efforts have been made toward comprehensive molecular characterization, ex vivo expansion of CTCs, and understanding the interactions between CTCs and their associated cells (e.g., immune cells and stromal cells) in the circulation. In this review, we briefly summarize existing CTC isolation technologies and specifically focus on advances in downstream analysis of CTCs and their potential applications in precision medicine. We also discuss the current challenges and future opportunities in their clinical utilization.

The clinical relevance of circulating tumor cell clusters (CTC-clusters) in breast cancer (BC) has been mostly studied using the CellSearch®, a marker-dependent method detecting only epithelial-enriched clusters. However, due to epithelial-to-mesenchymal transition, resorting to marker-independent approaches can improve CTC-cluster detection. Blood samples collected from healthy donors and spiked-in with tumor mammospheres, or from BC patients, were processed for CTC-cluster detection with 3 technologies: CellSearch®, CellSieve™ filters, and ScreenCell® filters. In spiked-in samples, the 3 technologies showed similar recovery capability, whereas, in 19 clinical samples processed in parallel with CellSearch® and CellSieve™ filters, filtration allowed us to detect more CTC-clusters than CellSearch® (median number = 7 versus 1, p = 0.0038). Next, samples from 37 early BC (EBC) and 23 metastatic BC (MBC) patients were processed using ScreenCell® filters for attaining both unbiased enrichment and marker-independent identification (based on cytomorphological criteria). At baseline, CTC-clusters were detected in 70% of EBC cases and in 20% of MBC patients (median number = 2, range 0-20, versus 0, range 0-15, p = 0.0015). Marker-independent approaches for CTC-cluster assessment improve detection and show that CTC-clusters are more frequent in EBC than in MBC patients, a novel finding suggesting that dissemination of CTC-clusters is an early event in BC natural history.

Circulating tumor microemboli (CTMs) are clusters of cancer cells detached from solid tumors, whose study can reveal mechanisms underlying metastatization. As they frequently comprise unknown fractions of leukocytes, the analysis of copy number alterations (CNAs) is challenging. To address this, we titrated known numbers of leukocytes into cancer cells (MDA-MB-453 and MDA-MB-36, displaying high and low DNA content, respectively) generating tumor fractions from 0-100%. After low-pass sequencing, ichorCNA was identified as the best algorithm to build a linear mixed regression model for tumor fraction (TF) prediction. We then isolated 53 CTMs from blood samples of six early-stage breast cancer patients and predicted the TF of all clusters. We found that all clusters harbor cancer cells between 8 and 48%. Furthermore, by comparing the identified CNAs of CTMs with their matched primary tumors, we noted that only 31-71% of aberrations were shared. Surprisingly, CTM-private alterations were abundant (30-63%), whereas primary tumor-private alterations were rare (4-12%). This either indicates that CTMs are disseminated from further progressed regions of the primary tumor or stem from cancer cells already colonizing distant sites. In both cases, CTM-private mutations may inform us about specific metastasis-associated functions of involved genes that should be explored in follow-up and mechanistic studies.

Metastasis-related events are the primary cause of cancer-related deaths, and circulating tumor cells (CTCs) have a pivotal role in metastatic relapse. CTCs include a variety of subtypes with different functional characteristics. Interestingly, the epithelial-mesenchymal transition (EMT) markers expressed in CTCs are strongly associated with poor clinical outcome and related to the acquisition of circulating tumor stem cell (CTSC) features. Recent studies have revealed the existence of CTC clusters, also called circulating tumor microemboli (CTM), which have a high metastatic potential. In this review, we present current opinions regarding the clinical significance of CTCs and CTM with a mesenchymal phenotype as clinical surrogate markers, and we summarize the therapeutic strategy according to phenotype characterization of CTCs in various types of cancers for future precision medicine.