Circulating tumor cells and their advances to promote cancer metastasis and relapse, with focus on glioblastoma multiforme

Circulating biomarkers in high-grade gliomas: current insights and future perspectives

PURPOSE

High-grade gliomas (HGG) represent a challenging subset of brain tumors characterized by aggressive nature and poor prognosis. Histopathology remains to be the standard for diagnosis, however, it is invasive, prone to sampling errors, and may not capture the full tumor heterogeneity and evolution over time. In recent years, there has been a growing interest in the potential utility of circulating biomarkers, obtained through minimally-invasive liquid biopsies, providing an opportunity for diagnosis, prognostication, monitoring treatment response and developing targeted therapies.

METHODS

We have reviewed the literature on circulating biomarkers for HGG, including circulating tumor cells (CTCs), circulating tumor-derived exosomes/extracellular vesicles (ctEVs), circulating tumor-derived DNA (ctDNA), circulating tumor-derived miRNA (ctmiRNA), and circulating tumor-derived proteins.

RESULTS

CTCs provide real-time information about tumor characteristics for molecular profiling and monitoring treatment response, yet their low numbers in circulation makes detection challenging. ctEVs carry a range of biomolecules and are easily detectable. However, they are not exclusively released from tumor cells and heterogeneity in their content requires standardized isolation and analysis methods. ctDNA is another promising biomarker with its levels correlating with the disease stage. However, its low concentration in blood requires highly sensitive techniques for identification and differentiation from normal cell-free DNA. ctmiRNA and tumor-derived proteins show promise but are limited by their susceptibility to dilution and lack of specificity in current technology.

CONCLUSION

This review highlights the transformative potential of circulating biomarkers in the management of HGG, with implications for improving patient outcomes, optimizing treatment strategies, and advancing precision oncology in neuro-oncology practice.

The prognostic significance of synchronous metastasis in glioblastoma multiforme patients: a propensity score-matched analysis using SEER data

Background

Glioblastoma multiforme (GBM) with synchronous metastasis(SM) is a rare occurrence. We extracted the data of GBM patients from the SEER database to look into the incidence of SM in GBM, determine the prognostic significance of SM in GBM, and assess therapeutic options for patients presenting with SM.

Methods

From 2004 to 2015, information on GBM patients was obtained from the Surveillance, Epidemiology, and End Results (SEER) database. The propensity score matching (PSM) method was employed to mitigate confounding factors between SM and non-SM groups, subsequently investigating the prognostic significance of SM in patients with GBM. Multivariate Cox proportional hazards regression analyses were employed to identify independent prognostic variables for GBM patients with SM. A forest plot was used to visualize the results.

Results

A cohort of 19,708 patients was obtained from the database, among which 272 (1.4%) had SM at the time of diagnosis. Following PSM at a 3:1 ratio, in both univariate and multivariate cox regression analysis, SM (HR = 1.27, 95% CI: 1.09-1.46) was found to be an independent predictive predictor for GBM patients. Furthermore, the Cox proportional hazard forest plot demonstrated that independent risk variables for GBM patients with SM included age (Old vs. Young, HR = 1.44, 95% CI: 1.11-1.88), surgery (biopsy vs. no surgery, HR = 0.67, 95% CI: 0.46-0.96;Subtotal resection vs. no surgery, HR = 0.47, 95% CI: 0.32-0.68;Gross total resection vs. no surgery, HR = 0.44, 95% CI: 0.31-0.62), radiotherapy (HR = 0.58, 95% CI: 0.41-0.83), and chemotherapy (HR = 0.51, 95% CI: 0.36-0.72).

Conclusion

The predictive value of SM in GBM was determined by this propensity-matched analysis using data from the SEER database. Radiotherapy, chemotherapy, and surgery constitute an effective treatment regimen for patients with SM. A more positive approach toward the use of aggressive treatment for GBM patients with SM may be warranted.

Circulating Liquid Biopsy Biomarkers in Glioblastoma: Advances and Challenges

Gliomas, particularly glioblastoma (GBM), represent the most prevalent and aggressive tumors of the central nervous system (CNS). Despite recent treatment advancements, patient survival rates remain low. The diagnosis of GBM traditionally relies on neuroimaging methods such as magnetic resonance imaging (MRI) or computed tomography (CT) scans and postoperative confirmation via histopathological and molecular analysis. Imaging techniques struggle to differentiate between tumor progression and treatment-related changes, leading to potential misinterpretation and treatment delays. Similarly, tissue biopsies, while informative, are invasive and not suitable for monitoring ongoing treatments. These challenges have led to the emergence of liquid biopsy, particularly through blood samples, as a promising alternative for GBM diagnosis and monitoring. Presently, blood and cerebrospinal fluid (CSF) sampling offers a minimally invasive means of obtaining tumor-related information to guide therapy. The idea that blood or any biofluid tests can be used to screen many cancer types has huge potential. Tumors release various components into the bloodstream or other biofluids, including cell-free nucleic acids such as microRNAs (miRNAs), circulating tumor DNA (ctDNA), circulating tumor cells (CTCs), proteins, extracellular vesicles (EVs) or exosomes, metabolites, and other factors. These factors have been shown to cross the blood-brain barrier (BBB), presenting an opportunity for the minimally invasive monitoring of GBM as well as for the real-time assessment of distinct genetic, epigenetic, transcriptomic, proteomic, and metabolomic changes associated with brain tumors. Despite their potential, the clinical utility of liquid biopsy-based circulating biomarkers is somewhat constrained by limitations such as the absence of standardized methodologies for blood or CSF collection, analyte extraction, analysis methods, and small cohort sizes. Additionally, tissue biopsies offer more precise insights into tumor morphology and the microenvironment. Therefore, the objective of a liquid biopsy should be to complement and enhance the diagnostic accuracy and monitoring of GBM patients by providing additional information alongside traditional tissue biopsies. Moreover, utilizing a combination of diverse biomarker types may enhance clinical effectiveness compared to solely relying on one biomarker category, potentially improving diagnostic sensitivity and specificity and addressing some of the existing limitations associated with liquid biomarkers for GBM. This review presents an overview of the latest research on circulating biomarkers found in GBM blood or CSF samples, discusses their potential as diagnostic, predictive, and prognostic indicators, and discusses associated challenges and future perspectives.

The Interplay between Glioblastoma Cells and Tumor Microenvironment: New Perspectives for Early Diagnosis and Targeted Cancer Therapy

Glioblastoma multiforme (GBM) stands out as the most tremendous brain tumor, constituting 60% of primary brain cancers, accompanied by dismal survival rates. Despite advancements in research, therapeutic options remain limited to chemotherapy and surgery. GBM molecular heterogeneity, the intricate interaction with the tumor microenvironment (TME), and non-selective treatments contribute to the neoplastic relapse. Diagnostic challenges arise from GBM advanced-stage detection, necessitating the exploration of novel biomarkers for early diagnosis. Using data from the literature and a bioinformatic tool, the current manuscript delineates the molecular interplay between human GBM, astrocytes, and myeloid cells, underscoring selected protein pathways belonging to astroglia and myeloid lineage, which can be considered for targeted therapies. Moreover, the pivotal role of extracellular vesicles (EVs) in orchestrating a favorable microenvironment for cancer progression is highlighted, suggesting their utility in identifying biomarkers for GBM early diagnosis.

Liquid biopsy: creating opportunities in brain space

In recent years, liquid biopsy has emerged as an alternative method to diagnose and monitor tumors. Compared to classical tissue biopsy procedures, liquid biopsy facilitates the repetitive collection of diverse cellular and acellular analytes from various biofluids in a non/minimally invasive manner. This strategy is of greater significance for high-grade brain malignancies such as glioblastoma as the quantity and accessibility of tumors are limited, and there are collateral risks of compromised life quality coupled with surgical interventions. Currently, blood and cerebrospinal fluid (CSF) are the most common biofluids used to collect circulating cells and biomolecules of tumor origin. These liquid biopsy analytes have created opportunities for real-time investigations of distinct genetic, epigenetic, transcriptomics, proteomics, and metabolomics alterations associated with brain tumors. This review describes different classes of liquid biopsy biomarkers present in the biofluids of brain tumor patients. Moreover, an overview of the liquid biopsy applications, challenges, recent technological advances, and clinical trials in the brain have also been provided.

The Current Landscape of Glioblastoma Biomarkers in Body Fluids

Glioblastoma (GBM) is a highly aggressive and lethal primary brain cancer that necessitates early detection and accurate diagnosis for effective treatment and improved patient outcomes. Traditional diagnostic methods, such as imaging techniques and tissue biopsies, have limitations in providing real-time information and distinguishing treatment-related changes from tumor progression. Liquid biopsies, used to analyze biomarkers in body fluids, offer a non-invasive and dynamic approach to detecting and monitoring GBM. This article provides an overview of GBM biomarkers in body fluids, including circulating tumor cells (CTCs), cell-free DNA (cfDNA), cell-free RNA (cfRNA), microRNA (miRNA), and extracellular vesicles. It explores the clinical utility of these biomarkers for GBM detection, monitoring, and prognosis. Challenges and limitations in implementing liquid biopsy strategies in clinical practice are also discussed. The article highlights the potential of liquid biopsies as valuable tools for personalized GBM management but underscores the need for standardized protocols and further research to optimize their clinical utility.

Liquid biomarkers in glioma

An ideal biomarker must meet several parameters to enable its successful adoption; however, the nature of glioma makes it challenging to discover valuable biomarkers. While biomarkers require simplicity for clinical implementation, anatomical features and the complexity of the brain make it challenging to perform histological examination. Therefore, compared to biomarkers from general histological examination, liquid biomarkers for brain disease offer many more advantages in these minimally invasive methods. Ideal biomarkers should have high sensitivity and specificity, especially in malignant tumors. The heterogeneous nature of glioma makes it challenging to determine useful common biomarkers, and no liquid biomarker has yet been adopted clinically. The low incidence of brain tumors also hinders research progress. To overcome these problems, clinical applications of new types of specimens, such as extracellular vesicles and comprehensive omics analysis, have been developed, and some candidate liquid biomarkers have been identified. As against previous reviews, we focused on and reviewed the sensitivity and specificity of each liquid biomarker for its clinical application. Perusing an ideal glioma biomarker would help uncover the common underlying mechanism of glioma and develop new therapeutic targets. Further multicenter studies based on these findings will help establish new treatment strategies in the future.

Circulating tumor nucleic acids: biology, release mechanisms, and clinical relevance

BACKGROUND

Despite advances in early detection and therapies, cancer is still one of the most common causes of death worldwide. Since each tumor is unique, there is a need to implement personalized care and develop robust tools for monitoring treatment response to assess drug efficacy and prevent disease relapse.

MAIN BODY

Recent developments in liquid biopsies have enabled real-time noninvasive monitoring of tumor burden through the detection of molecules shed by tumors in the blood. These molecules include circulating tumor nucleic acids (ctNAs), comprising cell-free DNA or RNA molecules passively and/or actively released from tumor cells. Often highlighted for their diagnostic, predictive, and prognostic potential, these biomarkers possess valuable information about tumor characteristics and evolution. While circulating tumor DNA (ctDNA) has been in the spotlight for the last decade, less is known about circulating tumor RNA (ctRNA). There are unanswered questions about why some tumors shed high amounts of ctNAs while others have undetectable levels. Also, there are gaps in our understanding of associations between tumor evolution and ctNA characteristics and shedding kinetics. In this review, we summarize current knowledge about ctNA biology and release mechanisms and put this information into the context of tumor evolution and clinical utility.

CONCLUSIONS

A deeper understanding of the biology of ctDNA and ctRNA may inform the use of liquid biopsies in personalized medicine to improve cancer patient outcomes.

EGFR/MET promotes hepatocellular carcinoma metastasis by stabilizing tumor cells and resisting to RTKs inhibitors in circulating tumor microemboli

The receptor tyrosine kinases (RTKs) family is well-recognized as vital targets for the treatment of hepatocarcinoma cancer (HCC) clinically, whereas the survival benefit of target therapy sorafenib is not satisfactory for liver cancer patients due to metastasis. EGFR and MET are two molecules of the RTK family that were related to the survival time of liver cancer patients and resistance to targeted therapy in clinical reports. However, the mechanism and clinical therapeutic value of EGFR/MET in HCC metastasis are still not completely clarified. The study confirmed that EGFR/MET was highly expressed in HCC cells and tissues and the phosphorylation was stable after metastasis. The expression of EGFR/MET was up-regulated in circulating tumor microemboli (CTM) to accelerate IL-8 production and resistance to the lethal effect of leukocytes. Meanwhile, highly expressed EGFR/MET effectively regulated the Ras/MAPK pathway and stabilized suspended HCC cells by facilitating proliferation and inhibiting apoptosis. Moreover, EGFR/MET promoted phosphorylation of hetero-RTKs, which was dependent on high-energy phosphoric acid compounds rather than their direct interactions. In conclusion, highly expressed EGFR/MET could be used in CTM identification and suitable for preventing metastasis of HCC in clinical practice.

Immunological insights of selectins in human disease mechanism

Selectin enzymes are glycoproteins and are an important adhesion molecule in the mammalian immune system, especially in the inflammatory response and the healing process of tissues. Selectins play an important role in a variety of biological processes, including the rolling of leukocytes in endothelial cells, a process known as the adhesion cascade. It has recently been discovered and reported that the selectin mechanism plays a role in cancer and thrombosis disease. This process begins with non-covalent interactions-based selectin-ligand binding and the glycans play a role as a connector between cancer cells and the endothelium in this process. The selectin mechanism is critical for the immune system, but it is also involved in disease mechanisms, earning the selectins the nickname "Selectins-The Two Dr. Jekyll and Mr. Hyde Faces". As a result, the drug for selectins should have a multifaceted role and be a dynamic molecule that targets the disease mechanism specifically. This chapter explores the role of selectins in the disease mechanism at the mechanism level that provides the impact for identifying the selectin inhibitors. Overall, this chapter provides the molecular level insights on selectins, their ligands, involvement in normal and disease mechanisms.

Identification of a novel circular RNA circZNF652/miR-486-5p/SERPINE1 signaling cascade that regulates cancer aggressiveness in glioblastoma (GBM)

Circular RNAs (circRNAs) are closely associated with cancer development in glioblastoma (GBM), and this study aims to explore the molecular mechanisms of a novel circular RNA circZNF652 in regulating GBM aggressiveness. The present study found that CircZNF652 and SERPINE1 were upregulated, while miR-486-5p was downregulated in GBM tissues and cell lines, and GBM patients with high expression of CircZNF652 and SERPINE1, and patients with low expression of miR-486-5p tended to have a worse prognosis. Further results validated that both silencing of circZNF652 and miR-486-5p overexpression suppressed cell growth, migration, invasion, epithelial-mesenchymal transition (EMT) and tumorigenesis in GBM cells in vitro and in vivo. Next, the underlying mechanisms were investigated, and we found that circZNF652 sponged miR-486-5p to upregulate SERPINE1 in GBM cells. Also, we validated that knock-down of circZNF652 regulated the miR-486-5p/SERPINE1 axis to reverse the malignant phenotypes in GBM cells. Interestingly, we noticed that GBM cells derived exosomes were characterized by high-expressed CircZNF652. Collectively, we concluded that targeting the circular RNA circZNF652/miR-486-5p/SERPINE1 axis was a novel and effective strategy to suppress cancer progression in GBM.

Isolation of Circulating Tumor Cells from Peripheral Blood Samples of Cancer Patients Using Microfluidic Technology

The aim of the investigation was to study the potential of an innovative microfluidic technology for the isolation of circulating tumor cells (CTCs) from the peripheral blood samples of cancer patients.

Prognostic and Predictive Biomarkers in Gliomas

Gliomas are the most common central nervous system tumors. New technologies, including genetic research and advanced statistical methods, revolutionize the therapeutic approach to the patient and reveal new points of treatment options. Moreover, the 2021 World Health Organization Classification of Tumors of the Central Nervous System has fundamentally changed the classification of gliomas and incorporated many molecular biomarkers. Given the rapid progress in neuro-oncology, here we compile the latest research on prognostic and predictive biomarkers in gliomas. In adult patients, IDH mutations are positive prognostic markers and have the greatest prognostic significance. However, CDKN2A deletion, in IDH-mutant astrocytomas, is a marker of the highest malignancy grade. Moreover, the presence of TERT promoter mutations, EGFR alterations, or a combination of chromosome 7 gain and 10 loss upgrade IDH-wildtype astrocytoma to glioblastoma. In pediatric patients, H3F3A alterations are the most important markers which predict the worse outcome. MGMT promoter methylation has the greatest clinical significance in predicting responses to temozolomide (TMZ). Conversely, mismatch repair defects cause hypermutation phenotype predicting poor response to TMZ. Finally, we discussed liquid biopsies, which are promising diagnostic, prognostic, and predictive techniques, but further work is needed to implement these novel technologies in clinical practice.

Emerging Technologies for Non-invasive Monitoring of Treatment Response to Immunotherapy for Brain Tumors

Glioblastoma is the most common primary malignant brain tumor and one of the most aggressive tumors across all cancer types with remarkable resistance to any treatment. While immunotherapy has shown a robust clinical benefit in systemic cancers, its benefit is still under investigation in brain cancers. The broader use of immunotherapy in clinical trials for glioblastoma has highlighted the challenges of traditional methods of monitoring progression via imaging. Development of new guidelines, advanced imaging techniques, and immune profiling have emerged to counter premature diagnoses of progressive disease. However, these approaches do not provide a timely diagnosis and are costly and time consuming. Surgery is currently the standard of care for diagnosis of pseudoprogression in cases where MRI is equivocal. However, it is invasive, risky, and disruptive to patient's lives and their oncological treatment. With its increased vascularity, glioblastoma is continually shedding tumor components into the vasculature including tumor cells, genetic material, and extracellular vesicles. These elements can be isolated from routine blood draws and provide a real-time non-invasive indicator of tumor progression. Liquid biopsy therefore presents as an attractive alternative to current methods to guide treatment. While the initial evaluation of liquid biopsy for brain tumors via identification of mutations in the plasma was disappointing, novel technologies and use of alternatives to plasma cell-free DNA analytes provide promise for an effective liquid biopsy approach in brain tumors. This review aims to summarize developments in the use of liquid biopsy to monitor glioblastoma, especially in the context of immunotherapy.

Liquid Biomarkers for Improved Diagnosis and Classification of CNS Tumors

Liquid biopsy, as a non-invasive technique for cancer diagnosis, has emerged as a major step forward in conquering tumors. Current practice in diagnosis of central nervous system (CNS) tumors involves invasive acquisition of tumor biopsy upon detection of tumor on neuroimaging. Liquid biopsy enables non-invasive, rapid, precise and, in particular, real-time cancer detection, prognosis and treatment monitoring, especially for CNS tumors. This approach can also uncover the heterogeneity of these tumors and will likely replace tissue biopsy in the future. Key components of liquid biopsy mainly include circulating tumor cells (CTC), circulating tumor nucleic acids (ctDNA, miRNA) and exosomes and samples can be obtained from the cerebrospinal fluid, plasma and serum of patients with CNS malignancies. This review covers current progress in application of liquid biopsies for diagnosis and monitoring of CNS malignancies.

Silencing ZEB2 Induces Apoptosis and Reduces Viability in Glioblastoma Cell Lines

Background: Glioma is an aggressive type of brain tumor that originated from neuroglia cells, accounts for about 80% of all malignant brain tumors. Glioma aggressiveness has been associated with extreme cell proliferation, invasion of malignant cells, and resistance to chemotherapies. Due to resistance to common therapies, glioma affected patients’ survival has not been remarkably improved. ZEB2 (SIP1) is a critical transcriptional regulator with various functions during embryonic development and wound healing that has abnormal expression in different malignancies, including brain tumors. ZEB2 overexpression in brain tumors is attributed to an unfavorable state of the malignancy. Therefore, we aimed to investigate some functions of ZEB2 in two different glioblastoma U87 and U373 cell lines. Methods: In this study, we investigated the effect of ZEB2 knocking down on the apoptosis, cell cycle, cytotoxicity, scratch test of the two malignant brain tumor cell lines U87 and U373. Besides, we investigated possible proteins and microRNA, SMAD2, SMAD5, and miR-214, which interact with ZEB2 via in situ analysis. Then we evaluated candidate gene expression after ZEB2-specific knocking down. Results: We found that ZEB2 suppression induced apoptosis in U87 and U373 cell lines. Besides, it had cytotoxic effects on both cell lines and reduced cell migration. Cell cycle analysis showed cell cycle arrest in G0/G1 and apoptosis induction in U87 and U373 cell lines receptively. Also, we have found that SAMAD2/5 expression was reduced after ZEB2-siRNA transfection and miR-214 upregulated after transfection. Conclusions: In line with previous investigations, our results indicated a critical oncogenic role for ZEB2 overexpression in brain glioma tumors. These properties make ZEB2 an essential molecule for further studies in the treatment of glioma cancer.

Pseudoprogression versus true progression in glioblastoma patients: A multiapproach literature review. Part 2 - Radiological features and metric markers

After chemoradiotherapy for glioblastoma, pseudoprogression can occur and must be distinguished from true progression to correctly manage glioblastoma treatment and follow-up. Conventional treatment response assessment is evaluated via conventional MRI (contrast-enhanced T1-weighted and T2/FLAIR), which is unreliable. The emergence of advanced MRI techniques, MR spectroscopy, and PET tracers has improved pseudoprogression diagnostic accuracy. This review presents a literature review of the different imaging techniques and potential imaging biomarkers to differentiate pseudoprogression from true progression.

Diagnosis of Glioma Molecular Markers by Terahertz Technologies

This review considers glioma molecular markers in brain tissues and body fluids, shows the pathways of their formation, and describes traditional methods of analysis. The most important optical properties of glioma markers in the terahertz (THz) frequency range are also presented. New metamaterial-based technologies for molecular marker detection at THz frequencies are discussed. A variety of machine learning methods, which allow the marker detection sensitivity and differentiation of healthy and tumor tissues to be improved with the aid of THz tools, are considered. The actual results on the application of THz techniques in the intraoperative diagnosis of brain gliomas are shown. THz technologies’ potential in molecular marker detection and defining the boundaries of the glioma’s tissue is discussed.

Suppression of store-operated Ca2+ entry regulated by silencing Orai1 inhibits C6 glioma cell motility via decreasing Pyk2 activity and promoting focal adhesion

Store-operated Ca²⁺ entry (SOCE) plays an important role in regulating Ca²⁺ influx, which participates in tumor cell survival and motility. We aim to elucidate the role of SOCE in the behavior of C6 glioma cells. Lentiviral vector inserted with the Orai1-targeting shRNA was used to inhibit SOCE in C6 glioma cells. The down-regulation of Orai1 was confirmed by western blot. The ability of shOrai1 or SOCE inhibitor (SKF96365) in regulating SOCE inhibition was evaluated by measuring Ca²⁺ concentration. Additionally, its effect on cell behavior was assessed using methyl thiazolyl tetrazolium (MTT) assay, wound healing assay, transwell assay, and adhesion assay. Focal adhesions were visualized by immunofluorescence assay. Further, the expression of proline-rich tyrosine kinase 2 (Pyk2) and phosphorylated Pyk2 (p-Pyk2) was analyzed using western blot. Both, SKF96365 treatment and the Orai1 down-regulation inhibited SOCE by perturbing Ca²⁺ influx. The inhibitory effects of shOrai1 on C6 cell proliferation, migration, and invasion were similar to that of SKF96365. Moreover, Orai1 inhibition enhanced C6 cell adhesion by increasing the size of focal adhesion plaques. The down-regulation of Pyk2 was observed in both SKF96365-treated and Orai1-silenced C6 cells. Additionally, Orai1 inhibition blocked AKT/mTOR, NFAT, and NF-κB pathways. The silencing of Orai1 inhibited the C6 glioma cell migration, invasion and contributed to focal adhesion.

7-dehydrocholesterol suppresses melanoma cell proliferation and invasion via Akt1/NF-κB signaling

Melanoma is the most lethal cutaneous cancer with a high metastatic rate worldwide, causing ~55,500 deaths annually. Although the selective B-Raf oncogene serine/threonine-kinase (BRAF) inhibitors, dabrafenib and vemurafenib, have been approved for the treatment of BRAF-mutant metastatic melanoma, the 5-year survival rate remains unfavorable due to acquired therapy resistance. Therefore, it is of great importance to develop alternative therapeutic drugs and uncover their mechanisms for the treatment of melanoma. 7-dehydrocholesterol (7-DHC) has been demonstrated to inhibit melanoma, but the mechanism is unclear. Therefore, the present study aimed to elucidate the mechanisms of the inhibitory effect of 7-DHC in melanoma cells via analyzing the proliferation, migration, apoptosis, cell cycle and transcriptional sequencing of melanoma cells treated with 7-DHC, as well as constructing a gene signature according to public data of patients with melanoma. In the present study, 7-DHC, the precursor of vitamin D₃, was able to induce apoptosis and inhibit cell proliferation and invasion of melanoma cells in a dose-dependent manner. RNA sequencing of melanoma cells treated with different concentrations of 7-DHC revealed that, compared with untreated melanoma cells, 65 genes were downregulated, and genes involved in the regulation of NF-ĸB import into the nucleus and NF-ĸB signaling were significantly repressed. Consistently, the Akt kinase family was one of most common somatic mutation hotspots in patients with melanoma according to The Cancer Genome Atlas enrichment analysis. Furthermore, 7-DHC decreased the phosphorylation of Akt1-Ser473 rather than that of MEK1, and the decreased phosphorylation of Akt1 subsequently inhibited the translocation of free RELA proto-oncogene NF-κB subunit to the nucleus. Finally, by intersecting downregulated genes by 7-DHC treatment and upregulated genes in patients with melanoma, a 7-DHC gene signature was identified, which was negatively associated with the prognosis. Overall, the present results demonstrated that 7-DHC suppressed melanoma cell proliferation and invasion via the Akt1/NF-ĸB signaling pathway, and 7-DHC key target genes were negatively associated with the prognosis. These findings highlight the potential application of 7-DHC for the treatment of melanoma in the future.

Electrical Impedance Spectroscopy for Monitoring Chemoresistance of Cancer Cells

Electrical impedance spectroscopy (EIS) is an electrokinetic method that allows for the characterization of intrinsic dielectric properties of cells. EIS has emerged in the last decade as a promising method for the characterization of cancerous cells, providing information on inductance, capacitance, and impedance of cells. The individual cell behavior can be quantified using its characteristic phase angle, amplitude, and frequency measurements obtained by fitting the input frequency-dependent cellular response to a resistor-capacitor circuit model. These electrical properties will provide important information about unique biomarkers related to the behavior of these cancerous cells, especially monitoring their chemoresistivity and sensitivity to chemotherapeutics. There are currently few methods to assess drug resistant cancer cells, and therefore it is difficult to identify and eliminate drug-resistant cancer cells found in static and metastatic tumors. Establishing techniques for the real-time monitoring of changes in cancer cell phenotypes is, therefore, important for understanding cancer cell dynamics and their plastic properties. EIS can be used to monitor these changes. In this review, we will cover the theory behind EIS, other impedance techniques, and how EIS can be used to monitor cell behavior and phenotype changes within cancerous cells.

Blood Biomarkers of Glioma in Response Assessment Including Pseudoprogression and Other Treatment Effects: A Systematic Review

Imaging-based monitoring of disease burden in glioma patients is frequently confounded by treatment effects. Circulating biomarkers could theoretically augment imaging-based response monitoring. This systematic review aimed to present and evaluate evidence for differential expression and diagnostic accuracy of circulating biomarkers with respect to outcomes of tumor response, progression, stable disease, and treatment effects (pseudoprogression, radionecrosis, pseudoresponse, and pseudolesions) in patients undergoing treatment for World Health Organization grades II-IV diffuse astrocytic and oligodendroglial tumors. MEDLINE, EMBASE, Web Of Science, and SCOPUS databases were searched until August 18, 2019, for observational or diagnostic studies on multiple circulating biomarker types: extracellular vesicles, circulating nucleic acids, circulating tumor cells, circulating proteins, and metabolites, angiogenesis related cells, immune cells, and other cell lines. Methodological quality of included studies was assessed using an adapted Quality Assessment of Diagnostic Accuracy Studies-2 tool, and level of evidence (IA-IVD) for individual biomarkers was evaluated using an adapted framework from the National Comprehensive Cancer Network guidelines on evaluating tumor marker utility. Of 13,202 unique records, 58 studies met the inclusion criteria. One hundred thirty-three distinct biomarkers were identified in a total of 1,853 patients across various treatment modalities. Fifteen markers for response, progression, or stable disease and five markers for pseudoprogression or radionecrosis reached level IB. No biomarkers reached level IA. Only five studies contained data for diagnostic accuracy measures. Overall methodological quality of included studies was low. While extensive data on biomarker dysregulation in varying response categories were reported, no biomarkers ready for clinical application were identified. Further assay refinement and evaluation in larger cohorts with diagnostic accuracy study designs are required. PROSPERO Registration: CRD42018110658.

Addition of Multimodal Immunotherapy to Combination Treatment Strategies for Children with DIPG: A Single Institution Experience

Background: The prognosis of children with diffuse intrinsic pontine glioma (DIPG) remains dismal despite radio- and chemotherapy or molecular-targeted therapy. Immunotherapy is a powerful and promising approach for improving the overall survival (OS) of children with DIPG. Methods: A retrospective analysis for feasibility, immune responsiveness, and OS was performed on 41 children treated in compassionate use with multimodal therapy consisting of Newcastle disease virus, hyperthermia, and autologous dendritic cell vaccines as part of an individualized combinatorial treatment approach for DIPG patients. Results: Patients were treated at diagnosis (n = 28) or at the time of progression (n = 13). In the case of 16 patients, histone H3K27M mutation was confirmed by analysis of biopsy (n = 9) or liquid biopsy (n = 9) specimens. PDL1 mRNA expression was detected in circulating tumor cells of ten patients at diagnosis. Multimodal immunotherapy was feasible as scheduled, until progression, in all patients without major toxicity. When immunotherapy was part of primary treatment, median PFS and OS were 8.4 m and 14.4 m from the time of diagnosis, respectively, with a 2-year OS of 10.7%. When immunotherapy was given at the time of progression, median PFS and OS were 6.5 m and 9.1 m, respectively. A longer OS was associated with a Th1 shift and rise in PanTum Detect test scores. Conclusions: Multimodal immunotherapy is feasible without major toxicity, and warrants further investigation as part of a combinatorial treatment approach for children diagnosed with DIPG.

Epithelial-mesenchymal transition may be involved in the immune evasion of circulating gastric tumor cells via downregulation of ULBP1

Background

Increasing numbers of studies have demonstrated that circulating tumor cells (CTCs) undergo a phenotypic change termed epithelial‐mesenchymal transition (EMT), and researchers have proposed that EMT might provide CTCs with increased potential to survive in the different microenvironments encountered during metastasis through various ways, such as by increasing cell survival and early colonization. However, the exact role of EMT in CTCs remains unclear.

Methods

In this study, we identified CTCs of 41 patients with gastric cancer using Cyttel‐CTC and im‐FISH (immune‐fluorescence in situ hybridization) methods, and tested the expression of EMT markers and ULBP1 (a major member of the NKG2D—natural killer [NK] group 2 member D—ligand family) on CTCs. Moreover, we investigated the relationship between the expression of EMT markers and ULBP1 on CTCs and gastric cancer cell lines.

Results

Our results showed that the CTCs of gastric cancer patients exhibited three EMT marker subtypes, and that the expression of ULBP1 was significantly lower on mesenchymal phenotypic CTCs (M⁺CTCs) than on epithelial phenotypic CTCs (E⁺CTCs). EMT induced by TGF‐β in vitro produced a similar phenomenon, and we therefore proposed that EMT might be involved in the immune evasion of CTCs from NK cells by altering the expression of ULBP1.

Conclusions

Our study indicated that EMT might play a vital role in the immune invasion of CTCs by regulating the expression of ULBP1 on CTCs. These findings could provide potential strategies for targeting the immune evasion capacity of CTCs.

Treatment with Gold Nanoparticles Using Cudrania tricuspidata Root Extract Induced Downregulation of MMP-2/-9 and PLD1 and Inhibited the Invasiveness of Human U87 Glioblastoma Cells

In this study, we aimed to elucidate the anti-invasive effects of Cudrania tricuspidata root-gold nanoparticles (CTR-GNPs) using glioblastoma cells. We demonstrated the rapid synthesis of CTR-GNPs using UV-vis spectra. The surface morphology, crystallinity, reduction, capsulation, and stabilization of CTR-GNPs were analyzed using high resolution transmission electron microscopy (HR-TEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), and Fourier-transform infrared spectroscopy (FT-IR). Furthermore, CTR-GNPs displayed excellent photocatalytic activity as shown by the photo-degradation of methylene blue and rhodamine B. Cell migration and invasion assays with human glioblastoma cells were performed to investigate the anti-invasive effect of CTR-GNPs on U87 cells that were treated with phorbol 12-myristate 13-acetate. The results show that CTR-GNPs can significantly inhibit both basal and phorbol 12-myristate 13-acetate (PMA)-induced migration and invasion ability. Importantly, treatment with CTR-GNPs significantly decreased the levels of metalloproteinase (MMP)-2/-9 and phospholipase D1 (PLD1) and protein but not PLD2, which is involved in the modulation of migration and the invasion of glioblastoma cells. These results present a novel mechanism showing that CTR-GNPs can attenuate the migration and invasion of glioblastoma cells induced by PMA through transcriptional and translational regulation of MMP-2/-9 and PLD1. Taken together, our results suggest that CTR-GNPs might be an excellent therapeutic alternative for wide range of glioblastomas.

Determination of the optimal detection time of circulating tumor cells for the postoperative monitoring of colorectal cancer

Circulating tumor cells (CTCs) are widely used in cancer screening and monitoring. The present study focused on investigating the optimal time for the postoperative CTC detection in patients with colorectal cancer (CRC) to obtain more accurate results and facilitate subsequent treatment. By subtraction enrichment immunofluorescence in situ hybridization detection of CTCs, the present study demonstrated that different postoperative detection times in CRC substantially influenced the CTC numbers. In total, 134 subjects were enrolled. Among 10 healthy individuals and 20 preoperative patients with CRC, no CTCs were identified in the healthy subjects, and CTCs were detected in 85% (17/20) of the preoperative patients. In total, 104 postoperative patients with CRC (53 males and 51 females) with a mean average age of 57.63 years were studied. The total CTC detection rate was 81.73% (85/104) and the mean average CTC numbers in patients with tumor stage (T) T1, T2, T3 and T4 were 4.00, 3.33, 5.90 and 5.64 per 7.50 ml of peripheral blood, respectively. The CTC number trends in these four tumor stages within 5, 6, 7 and 10 postoperative days were variable, and were the most stable at 7 days. Gradual upward trends in CTC numbers were observed after 5, 6 and 7 postoperative days, and this upward trend was more obvious after 7 days. Overall, the findings of the present study suggest that CTC detection in CRC should be performed after at least 7 postoperative days rather than within 7 postoperative days.

Epithelial-Mesenchymal Plasticity in Circulating Tumor Cells, the Precursors of Metastasis

Circulating tumor cells offer an unprecedented window into the metastatic cascade, and to some extent can be considered as intermediates in the process of metastasis. They exhibit dynamic oscillations in epithelial to mesenchymal plasticity and provide important opportunities for prognosis, therapy response monitoring, and targeting of metastatic disease. In this manuscript, we review the involvement of epithelial-mesenchymal plasticity in the early steps of metastasis and what we have learned about its contribution to genomic instability and genetic diversity, tumor progression and therapeutic responses using cell culture, mouse models and circulating tumor cells enriched from patients.

Current and Future Trends on Diagnosis and Prognosis of Glioblastoma: From Molecular Biology to Proteomics

Glioblastoma multiforme is the most aggressive malignant tumor of the central nervous system. Due to the absence of effective pharmacological and surgical treatments, the identification of early diagnostic and prognostic biomarkers is of key importance to improve the survival rate of patients and to develop new personalized treatments. On these bases, the aim of this review article is to summarize the current knowledge regarding the application of molecular biology and proteomics techniques for the identification of novel biomarkers through the analysis of different biological samples obtained from glioblastoma patients, including DNA, microRNAs, proteins, small molecules, circulating tumor cells, extracellular vesicles, etc. Both benefits and pitfalls of molecular biology and proteomics analyses are discussed, including the different mass spectrometry-based analytical techniques, highlighting how these investigation strategies are powerful tools to study the biology of glioblastoma, as well as to develop advanced methods for the management of this pathology.

Distribution of circulating tumor cell phenotype in early cervical cancer

Background and objective: Circulating tumor cells (CTCs) can be classified into three phenotypes based on epithelial-to-mesenchymal transition (EMT) markers, including epithelial CTCs, mesenchymal CTCs, and mixed phenotypic CTCs. This study is aimed to analyze the correlation between CTC phenotypes and the clinicopathological features of patients with early cervical cancer.

Methods: Peripheral blood samples were obtained from 90 patients with early cervical cancer. CTCs were isolated and classified. The correlations of CTC counts and CTC phenotypes with clinicopathological features of patients were analyzed.

Results: The positivity rate for CTCs in patients with stage I-IIA cervical cancer was 90%. An increased CTC number was observed in patients with FIGO stage II, pelvic lymph node metastasis, and lymphovascular involvement. There were 38.89% epithelial CTCs, 23.33% mesenchymal CTCs, and 14.44% mixed phenotypic CTCs, Mesenchymal CTCs were more common in patients with FIGO stage II, pelvic lymph node metastasis, lymphovascular involvement, and deep stromal invasion.

Conclusion: CTCs with mesenchymal phenotypes are closely related to pelvic lymph node metastasis and lymphatic vascular invasion in stage I-IIA cervical cancer. Detection of circulating tumor cell phenotypes is helpful for the early diagnosis of cervical cancer micro-metastasis and for the assessment of disease status.

Diagnostic and prognostic biomarkers in cholangiocarcinoma

The high mortality rate of cholangiocarcinoma (CCA) is due, in part, to the lack of non-invasive approaches able to accurately detect this silent tumour at early stages, when therapeutic options can be potentially curative or may at least increase the overall survival of patients. The fact that the majority of CCA tumours are not linked to any known aetiological factor highly compromises the monitoring of patients at risk for tumour development and also their early diagnosis. Combination of clinical/biochemical features, imaging techniques and analysis of non-specific tumour biomarkers in serum are commonly used to help in the diagnosis of CCA, but tumour biopsy is usually required to confirm the diagnosis. Moreover, no prognostic biomarkers are currently used in the clinical setting, deserving more innovative research, and international validation and consensus. Important efforts have been made in the last few years to identify accurate non-invasive biomarkers, by using innovative techniques and high-throughput omics technologies. This review summarizes and discusses the advances in the investigation of novel diagnostic and prognostic biomarkers in CCA and envisions the future directions in this field of research.

Podoplanin in Inflammation and Cancer

Podoplanin is a small cell-surface mucin-like glycoprotein that plays a crucial role in the development of the alveoli, heart, and lymphatic vascular system. Emerging evidence indicates that it is also involved in the control of mammary stem-cell activity and biogenesis of platelets in the bone marrow, and exerts an important function in the immune response. Podoplanin expression is upregulated in different cell types, including fibroblasts, macrophages, T helper cells, and epithelial cells, during inflammation and cancer, where it plays important roles. Podoplanin is implicated in chronic inflammatory diseases, such as psoriasis, multiple sclerosis, and rheumatoid arthritis, promotes inflammation-driven and cancer-associated thrombosis, and stimulates cancer cell invasion and metastasis through a variety of strategies. To accomplish its biological functions, podoplanin must interact with other proteins located in the same cell or in neighbor cells. The binding of podoplanin to its ligands leads to modulation of signaling pathways that regulate proliferation, contractility, migration, epithelial⁻mesenchymal transition, and remodeling of the extracellular matrix. In this review, we describe the diverse roles of podoplanin in inflammation and cancer, depict the protein ligands of podoplanin identified so far, and discuss the mechanistic basis for the involvement of podoplanin in all these processes.