Cell surface vimentin-positive circulating tumor cell-based relapse prediction in a long-term longitudinal study of postremission neuroblastoma patients

A comprehensive overview of liquid biopsy applications in pediatric solid tumors

Liquid biopsies are emerging as an alternative source for pediatric cancer biomarkers with potential applications during all stages of patient care, from diagnosis to long-term follow-up. While developments within this field are reported, these mainly focus on dedicated items such as a specific liquid biopsy matrix, analyte, and/or single tumor type. To the best of our knowledge, a comprehensive overview is lacking. Here, we review the current state of liquid biopsy research for the most common non-central nervous system pediatric solid tumors. These include neuroblastoma, renal tumors, germ cell tumors, osteosarcoma, Ewing sarcoma, rhabdomyosarcoma and other soft tissue sarcomas, and liver tumors. Within this selection, we discuss the most important or recent studies involving liquid biopsy-based biomarkers, anticipated clinical applications, and the current challenges for success. Furthermore, we provide an overview of liquid biopsy-based biomarker publication output for each tumor type based on a comprehensive literature search between 1989 and 2023. Per study identified, we list the relevant liquid biopsy-based biomarkers, matrices (e.g., peripheral blood, bone marrow, or cerebrospinal fluid), analytes (e.g., circulating cell-free and tumor DNA, microRNAs, and circulating tumor cells), methods (e.g., digital droplet PCR and next-generation sequencing), the involved pediatric patient cohort, and proposed applications. As such, we identified 344 unique publications. Taken together, while the liquid biopsy field in pediatric oncology is still behind adult oncology, potentially relevant publications have increased over the last decade. Importantly, steps towards clinical implementation are rapidly gaining ground, notably through validation of liquid biopsy-based biomarkers in pediatric clinical trials.

Exploring new frontiers: cell surface vimentin as an emerging marker for circulating tumor cells and a promising therapeutic target in advanced gastric Cancer

BACKGROUND

Circulating tumor cells (CTCs) hold immense promise in guiding treatment strategies for advanced gastric cancer (GC). However, their clinical impact has been limited due to challenges in identifying epithelial-mesenchymal transition (EMT)-CTCs using conventional methods.

METHODS

To bridge this knowledge gap, we established a detection platform for CTCs based on the distinctive biomarker cell surface vimentin (CSV). A prospective study involving 127 GC patients was conducted, comparing CTCs enumeration using both EpCAM and CSV. This approach enabled the detection of both regular and EMT-CTCs, providing a comprehensive analysis. Spiking assays and WES were employed to verify the reliability of this marker and technique. To explore the potential inducer of CSV+CTCs formation, a combination of Tandem Mass Tag (TMT) quantitative proteomics, m6A RNA immunoprecipitation-qPCR (MeRIP-qPCR), single-base elongation- and ligation-based qPCR amplification method (SELECT) and RNA sequencing (RNA-seq) were utilized to screen and confirm the potential target gene. Both in vitro and in vivo experiments were performed to explore the molecular mechanism of CSV expression regulation and its role in GC metastasis.

RESULTS

Our findings revealed the potential of CSV in predicting therapeutic responses and long-term prognosis for advanced GC patients. Additionally, compared to the conventional EpCAM-based CTCs detection method, the CSV-specific positive selection CTCs assay was significantly better for evaluating the therapeutic response and prognosis in advanced GC patients and successfully predicted disease progression 14.25 months earlier than radiology evaluation. Apart from its excellent role as a detection marker, CSV emerges as a promising therapeutic target for attenuating GC metastasis. It was found that fat mass and obesity associated protein (FTO) could act as a potential catalyst for CSV+CTCs formation, and its impact on the insulin-like growth factor-I receptor (IGF-IR) mRNA decay through m6A modification. The activation of IGF-I/IGF-IR signaling enhanced the translocation of vimentin from the cytoplasm to the cell surface through phosphorylation of vimentin at serine 39 (S39). In a GC mouse model, the simultaneous inhibition of CSV and blockade of the IGF-IR pathway yielded promising outcomes.

CONCLUSION

In summary, leveraging CSV as a universal CTCs marker represents a significant breakthrough in advancing personalized medicine for patients with advanced GC. This research not only paves the way for tailored therapeutic strategies but also underscores the pivotal role of CSV in enhancing GC management, opening new frontiers for precision medicine.

Liquid biopsy in lung cancer

Lung cancer is a highly prevalent malignancy worldwide and the primary cause of mortality. The absence of systematic and standardized diagnostic approaches for identifying potential pulmonary nodules, early-stage cancers, and indeterminate tumors has led clinicians to consider tissue biopsy and pathological sections as the preferred method for clinical diagnosis, often regarded as the gold standard. The conventional tissue biopsy is an invasive procedure that does not adequately capture the diverse characteristics and evolving nature of tumors. Recently, the concept of 'liquid biopsy' has gained considerable attention as a promising solution. Liquid biopsy is a non-invasive approach that facilitates repeated analysis, enabling real-time monitoring of tumor recurrence, metastasis, and response to treatment. Currently, liquid biopsy includes circulating tumor cells, circulating cell-free DNA, circulating tumor DNA, circulating cell-free RNA, extracellular vesicles, and other proteins and metabolites. With rapid progress in molecular technology, liquid biopsy has emerged as a highly promising and intriguing approach, yielding compelling results. This article critically examines the significant role and potential clinical implications of liquid biopsy in the diagnosis, treatment, and prognosis of lung cancer.

Eflornithine as Postimmunotherapy Maintenance in High-Risk Neuroblastoma: Externally Controlled, Propensity Score-Matched Survival Outcome Comparisons

PURPOSE

Long-term survival in high-risk neuroblastoma (HRNB) is approximately 50%, with mortality primarily driven by relapse. Eflornithine (DFMO) to reduce risk of relapse after completion of immunotherapy was investigated previously in a single-arm, phase II study (NMTRC003B; ClinicalTrials.gov identifier: NCT02395666) that suggested improved event-free survival (EFS) and overall survival (OS) compared with historical rates in a phase III trial (Children Oncology Group ANBL0032; ClinicalTrials.gov identifier: NCT00026312). Using patient-level data from ANBL0032 as an external control, we present new analyses to further evaluate DFMO as HRNB postimmunotherapy maintenance.

PATIENTS AND METHODS

NMTRC003B (2012-2016) enrolled patients with HRNB (N = 141) after standard up-front or refractory/relapse treatment who received up to 2 years of continuous treatment with oral DFMO (750 ± 250 mg/m2 twice a day). ANBL0032 (2001-2015) enrolled patients with HRNB postconsolidation, 1,328 of whom were assigned to dinutuximab (ch.14.18) treatment. Selection rules identified 92 NMTRC003B patients who participated in (n = 87) or received up-front treatment consistent with (n = 5) ANBL0032 (the DFMO/treated group) and 852 patients from ANBL0032 who could have been eligible for NMTRC003B after immunotherapy, but did not enroll (the NO-DFMO/control group). The median follow-up time for DFMO/treated patients was 6.1 years (IQR, 5.2-7.2) versus 5.0 years (IQR, 3.5-7.0) for NO-DFMO/control patients. Kaplan-Meier and Cox regression compared EFS and OS for overall groups, 3:1 (NO-DFMO:DFMO) propensity score-matched cohorts balanced on 11 baseline demographic and disease characteristics with exact matching on MYCN, and additional sensitivity analyses.

RESULTS

DFMO after completion of immunotherapy was associated with improved EFS (hazard ratio [HR], 0.50 [95% CI, 0.29 to 0.84]; P = .008) and OS (HR, 0.38 [95% CI, 0.19 to 0.76]; P = .007). The results were confirmed with propensity score-matched cohorts and sensitivity analyses.

CONCLUSION

The externally controlled analyses presented show a relapse risk reduction in patients with HRNB treated with postimmunotherapy DFMO.

Extracellular vimentin: Battle between the devil and the angel

Vimentin, an intracellular cytoskeletal protein, can be secreted by various cells in response to conditions such as injury, stress, senescence, and cancer. Once vimentin is secreted outside of the cell, it is called extracellular vimentin. This extracellular vimentin is significantly involved in pathological conditions, particularly in the areas of viral infection, cancer, immune response, and wound healing. The effects of extracellular vimentin can be either positive or negative, for example it can enhance axonal repair but also mediates SARS-CoV-2 infection. In this review, we categorize the functional implications of extracellular vimentin based on its localization outside the cell. Specifically, we classify extracellular vimentin into two distinct forms: surface vimentin, which remains bound to the cell surface, and secreted vimentin, which refers to the free form that is completely released outside the cell. Overall, extracellular vimentin has a dual nature that encompasses both beneficial and detrimental effects on the functionality of cells, organs and whole organisms. Here, we summarize its effects in viral infection, cancer, immune response and wound healing. We find that surface vimentin is often associated with negative consequences, whereas secreted vimentin manifests predominantly with positive influences. We found that the observed effects of extracellular vimentin strongly depend on the specific circumstances under which its expression occurs in cells.

Diagnostic value of exfoliated tumor cells combined with DNA methylation in bronchoalveolar lavage fluid for lung cancer

BACKGROUND

To evaluate the diagnostic value of exfoliated tumor cells (ETCs) numbers combined with DNA methylation levels in bronchoalveolar lavage fluid (BALF) in lung cancer.

METHODS

BALF samples were collected from 43 patients with lung cancer and 23 with benign lung disease. ETCs were detected by the nano-enrichment method, and the methylation status of the short stature homeobox gene 2 (SHOX2) and the RAS association domain family 1, isoform A (RASSF1A) gene were detected by RT-PCR. The diagnostic value of each metric was evaluated by receiver operating characteristic curve analysis, specificity and sensitivity.

RESULTS

The sensitivity/specificity of RASSF1A and SHOX2 methylation detection were 44.12%/76.47% and 93.75%/87.50%, respectively. When "RASSF1A/SHOX2 methylation" was used as a positive result, the sensitivity increased to 88.24%, and the specificity decreased to 81.25%. When "RASSF1A + SHOX methylation" was used as positive, the sensitivity was reduced to 32.35%, but the specificity was increased to 100.00%. The sensitivity and specificity of ETCs detection in BALF were 89.47% and 16.67%, respectively. When "SHOX2/RASSF1A methylation + ETCs was used as a positive result, the sensitivity and specificity of the detection were 79.31% and 81.82%, respectively. When "SHOX2 + RASSF1A + ETCs" was used as positive, the sensitivity was 34.48% and the specificity was 90.91%. Receiver operating characteristic curve analysis showed that when SHOX2, RASSF1A methylation and ETCs were combined, the diagnostic sensitivity increased to 0.778.

CONCLUSION

ETCs counting in combination with SHOX2 and RASSF1A methylation assays in BALF samples has demonstrated excellent sensitivity for lung cancer diagnosis and is an effective complementary tool for clinical diagnosis of lung cancer.

Phytogalactolipids activate humoral immunity against colorectal cancer

BACKGROUND

Colorectal cancer (CRC) is the third most lethal cancer in the world, and its incidence is steadily rising. In this study, we investigated the induction of humoral immunity by a phytogalactolipid enriched fraction (CRA) derived from the medicinal plant Crassocephalum rabens (Benth.) S. Moore to combat CRC.

METHODS

Immunocompetent BALB/c mice were used to evaluate CRA's therapeutic effects in CRC. The phenotypes of B cell subsets in splenocytes and tumors from the CRA-treated mice were isolated and analyzed by flow cytometry. The titers, isotypes, specificity, antigen recognition, and cytotoxic activity of CRA-induced anti-tumor antibodies were determined. The mechanisms of CRA on B cell differentiation were determined by cell-based analyses, including co-cultural with T cells, cytokine analysis, gene expression by qPCR, and protein expression by western blotting.

RESULTS

CRA efficiently inhibited tumor growth in colorectal tumor-bearing allograft mice. CRA treatment attracted an abundance of B cells into the tumor consequently enhancing the anti-tumor antibodies in sera and inducing a class-switch. CRA-induced antisera (designated CRA antisera) specifically recognized surface antigens on the plasma membrane of cancer cells. CRA antisera induced cytotoxicity including antibody-dependent cell cytotoxicity, phagocytosis, and complement-dependent cytotoxicity. CRA interacted with IL-6 receptor to activate STAT3 and cMaf, resulting in T cell secretion of IL-21, which, in turn induced B cell differentiation through the IL-21R/STAT3/Blimp-1 pathway.

CONCLUSIONS

CRA regulated T cell activity resulting in B cell activation and triggering of anti-tumor antibodies to impede CRC progression.

Phenotypic Plasticity in Circulating Tumor Cells Is Associated with Poor Response to Therapy in Metastatic Breast Cancer Patients

Circulating tumor cells (CTCs) are indicators of metastatic spread and progression. In a longitudinal, single-center trial of patients with metastatic breast cancer starting a new line of treatment, a microcavity array was used to enrich CTCs from 184 patients at up to 9 timepoints at 3-month intervals. CTCs were analyzed in parallel samples from the same blood draw by imaging and by gene expression profiling to capture CTC phenotypic plasticity. Enumeration of CTCs by image analysis relying primarily on epithelial markers from samples obtained before therapy or at 3-month follow-up identified the patients at the highest risk of progression. CTC counts decreased with therapy, and progressors had higher CTC counts than non-progressors. CTC count was prognostic primarily at the start of therapy in univariate and multivariate analyses but had less prognostic utility at 6 months to 1 year later. In contrast, gene expression, including both epithelial and mesenchymal markers, identified high-risk patients after 6-9 months of treatment, and progressors had a shift towards mesenchymal CTC gene expression on therapy. Cross-sectional analysis showed higher CTC-related gene expression in progressors 6-15 months after baseline. Furthermore, patients with higher CTC counts and CTC gene expression experienced more progression events. Longitudinal time-dependent multivariate analysis indicated that CTC count, triple-negative status, and CTC expression of FGFR1 significantly correlated with inferior progression-free survival while CTC count and triple-negative status correlated with inferior overall survival. This highlights the utility of protein-agnostic CTC enrichment and multimodality analysis to capture the heterogeneity of CTCs.

Pro-metastatic and mesenchymal gene expression signatures characterize circulating tumor cells of neuroblastoma patients with bone marrow metastases and relapse

Existing marker-based methods of minimal residual disease (MRD) determination in neuroblastoma do not effectively enrich for the circulating disease cell population. Given the relative size differential of neuroblastoma tumor cells over normal hematogenous cells, we hypothesized that cell size-based separation could enrich circulating tumor cells (CTCs) from blood samples and disseminated tumor cells (DTCs) from bone marrow aspirates (BMA) of neuroblastoma patients, and that their gene expression profiles could vary dynamically with various disease states over the course of treatment. Using a spiral microfluidic chip, peripheral blood of 17 neuroblastoma patients at 3 serial treatment timepoints (diagnosis, n=17; post-chemotherapy, n=11; and relapse, n=3), and bone marrow samples at diagnosis were enriched for large intact circulating cells. Profiling the resulting enriched samples with immunohistochemistry and mRNA expression of 1490 cancer-related genes via NanoString, 13 of 17 samples contained CTCs displaying cytologic atypia, TH and PHOX2B expression and/or upregulation of cancer-associated genes. Gene signatures reflecting pro-metastatic processes and the neuroblastoma mesenchymal super-enhancer state were consistently upregulated in 7 of 13 samples, 6 of which also had metastatic high-risk disease. Expression of 8 genes associated with PI3K and GCPR signaling were significantly upregulated in CTCs of patients with bone marrow metastases versus patients without. Correspondingly, in patients with marrow metastases, differentially-expressed gene signatures reflected upregulation of immune regulation in bone marrow DTCs versus paired CTCs samples. In patients who later developed disease relapse, 5 genes involved in immune cell regulation, JAK/STAT signaling and the neuroblastoma mesenchymal super-enhancer state (OLFML2B, STAT1, ARHGDIB, STAB1, TLR2) were upregulated in serial CTC samples over their disease course, despite urinary catecholamines and bone marrow aspirates not indicating the disease recurrences. In summary, using a label-free cell size-based separation method, we enriched and characterized intact circulating cells in peripheral blood indicative of neuroblastoma CTCs, as well as their DTC counterparts in the bone marrow. Expression profiles of pro-metastatic genes in CTCs correlated with the presence of bone marrow metastases at diagnosis, while longitudinal profiling identified persistently elevated expression of genes in CTCs that may serve as novel predictive markers of hematogenous MRD in neuroblastoma patients that subsequently relapse.

Application of circulating tumour cells to predict response to treatment in head and neck cancer

Background

Local recurrence and metastasis remain the major causes of death in head and neck cancer (HNC) patients. Circulating tumour cells (CTCs) are shed from primary and metastatic sites into the circulation system and have been reported to play critical roles in the metastasis and recurrence of HNC. Here, we explored the use of CTCs to predict the response to treatment and disease progression in HNC patients.

Methods

Blood samples were collected at diagnosis from HNC patients (n = 119). CTCs were isolated using a spiral microfluidic device and were identified using immunofluorescence staining. Correlation of baseline CTC numbers to 13-week PET-CT data and multidisciplinary team consensus data were conducted.

Results

CTCs were detected in 60/119 (50.4%) of treatment naïve HNC patients at diagnosis. Baseline CTC numbers were higher in stage III vs. stage I-II p16-positive oropharyngeal cancers (OPCs) and other HNCs (p = 0.0143 and 0.032, respectively). In addition, we found that baseline CTC numbers may serve as independent predictors of treatment response, even after adjusting for other conventional prognostic factors. CTCs were detected in 10 out of 11 patients exhibiting incomplete treatment responses.

Conclusions

We found that baseline CTC numbers are correlated with treatment response in patients with HNC. The expression level of cell-surface vimentin (CSV) on CTCs was significantly higher in patients with persistent or progressive disease, thus providing additional prognostic information for stratifying the risk at diagnosis in HNC patients. The ability to detect CTCs at diagnosis allows more accurate risk stratification, which in the future may be translated into better patient selection for treatment intensification and/or de-intensification strategies.

Supplementary information

The online version contains supplementary material available at 10.1007/s13402-022-00681-w.

Identification of epithelial and mesenchymal circulating tumor cells in clonal lineage of an aggressive prostate cancer case

Little is known about the complexity and plasticity of circulating tumor cell (CTC) biology in different compartments of the fluid microenvironment during tumor metastasis. Here we integrated phenomics, genomics, and targeted proteomics to characterize CTC phenotypic and genotypic heterogeneity in paired peripheral blood (PB) and bone marrow aspirate (BMA) from a metastatic prostate cancer patient following the rapid disease progression, using the High-Definition Single Cell Assay 3.0 (HDSCA3.0). Uniquely, we identified a subgroup of genetically clonal CTCs that acquired a mesenchymal-like state and its presence was significantly associated with one subclone that emerged along the clonal lineage. Higher CTC abundance and phenotypic diversity were observed in the BMA than PB and differences in genomic alterations were also identified between the two compartments demonstrating spatial heterogeneity. Single cell copy number profiling further detected clonal heterogeneity within clusters of CTCs (also known as microemboli or aggregates) as well as phenotypic variations by targeted proteomics. Overall, these results identify epithelial and mesenchymal CTCs in the clonal lineage of an aggressive prostate cancer case and also demonstrate a single cell multi-omic approach to deconvolute the heterogeneity and association of CTC phenotype and genotype in multi-medium liquid biopsies of metastatic prostate cancer.

Circulating tumor cells in neuroblastoma: Current status and future perspectives

Neuroblastoma is the most common extracranial solid tumor in children, accounting for 10% to 20% of deaths of pediatric malignancies. Due to the poor prognosis and significant biological heterogeneity of neuroblastoma, it is essential to develop personalized therapeutics and monitor treatment response. Circulating tumor cells (CTCs), as one of the important analytes for liquid biopsy, could facilitate response assessment and outcome prediction for patients in a non-invasive way. Several methods and platforms have been used for the enrichment and detection of CTCs. The enumeration of CTCs counts and evaluation of tumor-specific mRNA transcript levels could provide prognostic information at diagnosis, during or after chemotherapy, and during the process of disease progression. So far, studies into neuroblastoma CTCs are only in the preliminary stages. The quality-controlled large prospective cohort studies are needed to evaluate the clinical significance and statistical rigor of CTC detection methods. Moreover, there remains a lot to be explored and investigated in genotyping characterization of neuroblastoma (NB) CTCs and construction of in-vitro or in-vivo functional models. CTCs and circulating tumor DNA (ctDNA) analysis will be complementary in understanding tumor heterogeneity and evolution over the course of therapy for patients with NB in the future.

The expression of PHOX2B in bone marrow and peripheral blood predicts adverse clinical outcome in non-high-risk neuroblastoma

Paired-like homeobox 2B (PHOX2B) is a highly sensitive and specific biomarker for diagnosing neuroblastoma, as well as detecting minimal residual disease in neuroblastoma. The clinical significance of PHOX2B expression in bone marrow (BM) and peripheral blood (PB) samples of newly diagnosed patients with very low-, low- and intermediate-risk neuroblastoma remains unknown, to the best of our knowledge. The expression level of PHOX2B in paired BM and PB samples of patients with newly diagnosed neuroblastoma was validated using reverse transcription-quantitative polymerase chain reaction (RTqPCR). Among the 132 patients, 26 exhibited a positive PHOX2B expression BM (19.7%) and 11 in PB (8.3%) samples. PHOX2B was highly expressed in BM and PB samples from patients aged <18 months, with International Neuroblastoma Risk Group Staging System stages M and MS, 1p loss of heterozygosity, and high levels of lactate dehydrogenase, serum ferritin and neuron-specific enolase (p < 0.05). In all eligible patients, the 2-year event-free survival (EFS) and overall survival (OS) rates were 94.7 ± 2.0% and 97.7 ± 1.3%, respectively. However, the 2-year EFS rates were significantly decreased to 76.9 ± 8.3% and 63.6 ± 14.5% in patients with a positive PHOX2B expression in BM and PB samples, respectively (p < 0.05). Similarly, the 2-year OS rates were also decreased to 88.5 ± 6.3% and 81.8 ± 11.6% in patients with a positive PHOX2B expression in BM and PB samples, respectively (p < 0.05). In conclusion, a positive PHOX2B expression in BM and PB samples at diagnosis had a strong adverse prognostic effect on patients with non-high-risk neuroblastoma.

Recent clinical research on the application of liquid biopsy in neuroblastoma

Neuroblastoma (NB) is the most common extracranial solid tumor in children and has the features of high recurrence rate and low survival rate, and therefore, early diagnosis, treatment response evaluation, and recurrence monitoring are of great significance for NB patients. Liquid biopsy refers to the detection of cells and nucleic acids in fluid specimens, mainly blood. It is noninvasive and can overcome tumor heterogeneity, thus making it possible to achieve the early diagnosis and dynamic detection of NB. This review introduces the latest advances in clinical research on the application of liquid biopsy in NB.

Extracellular Vimentin as a Target Against SARS-CoV-2 Host Cell Invasion

Infection of human cells by pathogens, including SARS-CoV-2, typically proceeds by cell surface binding to a crucial receptor. The primary receptor for SARS-CoV-2 is the angiotensin-converting enzyme 2 (ACE2), yet new studies reveal the importance of additional extracellular co-receptors that mediate binding and host cell invasion by SARS-CoV-2. Vimentin is an intermediate filament protein that is increasingly recognized as being present on the extracellular surface of a subset of cell types, where it can bind to and facilitate pathogens' cellular uptake. Biophysical and cell infection studies are done to determine whether vimentin might bind SARS-CoV-2 and facilitate its uptake. Dynamic light scattering shows that vimentin binds to pseudovirus coated with the SARS-CoV-2 spike protein, and antibodies against vimentin block in vitro SARS-CoV-2 pseudovirus infection of ACE2-expressing cells. The results are consistent with a model in which extracellular vimentin acts as a co-receptor for SARS-CoV-2 spike protein with a binding affinity less than that of the spike protein with ACE2. Extracellular vimentin may thus serve as a critical component of the SARS-CoV-2 spike protein-ACE2 complex in mediating SARS-CoV-2 cell entry, and vimentin-targeting agents may yield new therapeutic strategies for preventing and slowing SARS-CoV-2 infection.

Prognostic Value of Cell-Surface Vimentin-Positive CTCs in Pediatric Sarcomas

BACKGROUND

Despite advances in care, the 5 year overall survival for patients with relapsed and or metastatic sarcoma remains as low as < 35%. Currently, there are no biomarkers available to assess disease status in patients with sarcomas and as such, disease surveillance remains reliant on serial imaging which increases the risk of secondary malignancies and heightens patient anxiety.

METHODS

Here, for the first time reported in the literature, we have enumerated the cell surface vimentin (CSV+) CTCs in the blood of 92 sarcoma pediatric and adolescent and young adult (AYA) patients as a possible marker of disease.

RESULTS

We constructed a ROC with an AUC of 0.831 resulting in a sensitivity of 85.3% and a specificity of 75%. Additionally, patients who were deemed to be CSV+ CTC positive were found to have a worse overall survival compared to those who were CSV+ CTC negative. We additionally found the use of available molecular testing increased the accuracy of our diagnostic and prognostic tests.

CONCLUSIONS

Our findings indicate that CSV+ CTCs have prognostic value and can possibly serve as a measure of disease burden.

Extracellular vimentin as a target against SARS-CoV-2 host cell invasion

Infection of human cells by pathogens, including SARS-CoV-2, typically proceeds by cell surface binding to a crucial receptor. In the case of SARS-CoV-2, angiotensin-converting enzyme 2 (ACE2) has been identified as a necessary receptor, but not all ACE2-expressing cells are equally infected, suggesting that other extracellular factors are involved in host cell invasion by SARS-CoV-2. Vimentin is an intermediate filament protein that is increasingly recognized as being present on the extracellular surface of a subset of cell types, where it can bind to and facilitate pathogens' cellular uptake. Here, we present evidence that extracellular vimentin might act as a critical component of the SARS-CoV-2 spike protein-ACE2 complex in mediating SARS-CoV-2 cell entry. We demonstrate direct binding between vimentin and SARS-CoV-2 pseudovirus coated with the SARS-CoV-2 spike protein and show that antibodies against vimentin block in vitro SARS-CoV-2 pseudovirus infection of ACE2-expressing cells. Our results suggest new therapeutic strategies for preventing and slowing SARS-CoV-2 infection, focusing on targeting cell host surface vimentin.

Mesenchymal Characteristics and Predictive Biomarkers on Circulating Tumor Cells for Therapeutic Strategy

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.

Mechanical and Non-Mechanical Functions of Filamentous and Non-Filamentous Vimentin

Intermediate filaments (IFs) formed by vimentin are less understood than their cytoskeletal partners, microtubules and F-actin, but the unique physical properties of IFs, especially their resistance to large deformations, initially suggest a mechanical function. Indeed, vimentin IFs help regulate cell mechanics and contractility, and in crowded 3D environments they protect the nucleus during cell migration. Recently, a multitude of studies, often using genetic or proteomic screenings show that vimentin has many non-mechanical functions within and outside of cells. These include signaling roles in wound healing, lipogenesis, sterol processing, and various functions related to extracellular and cell surface vimentin. Extracellular vimentin is implicated in marking circulating tumor cells, promoting neural repair, and mediating the invasion of host cells by viruses, including SARS-CoV, or bacteria such as Listeria and Streptococcus. These findings underscore the fundamental role of vimentin in not only cell mechanics but also a range of physiological functions. Also see the video abstract here https://youtu.be/YPfoddqvz-g.