Therapeutic targeting of VEGF in the treatment of glioblastoma

Integration of Computational Pipeline to Streamline Efficacious Drug Nomination and Biomarker Discovery in Glioblastoma

Glioblastoma multiforme (GBM) is the deadliest, most heterogeneous, and most common brain cancer in adults. Not only is there an urgent need to identify efficacious therapeutics, but there is also a great need to pair these therapeutics with biomarkers that can help tailor treatment to the right patient populations. We built patient drug response models by integrating patient tumor transcriptome data with high-throughput cell line drug screening data as well as Bayesian networks to infer relationships between patient gene expression and drug response. Through these discovery pipelines, we identified agents of interest for GBM to be effective across five independent patient cohorts and in a mouse avatar model: among them are a number of MEK inhibitors (MEKis). We also predicted phosphoglycerate dehydrogenase enzyme (PHGDH) gene expression levels to be causally associated with MEKi efficacy, where knockdown of this gene increased tumor sensitivity to MEKi and overexpression led to MEKi resistance. Overall, our work demonstrated the power of integrating computational approaches. In doing so, we quickly nominated several drugs with varying known mechanisms of action that can efficaciously target GBM. By simultaneously identifying biomarkers with these drugs, we also provide tools to select the right patient populations for subsequent evaluation.

Radiogenomic Analysis of Vascular Endothelial Growth Factor in Patients With Glioblastoma

OBJECTIVES

This article aims to predict the presence of vascular endothelial growth factor (VEGF) expression and to predict the expression level of VEGF by machine learning based on preoperative magnetic resonance imaging (MRI) of glioblastoma (GBM).

METHODS

We analyzed the axial T2-weighted images (T2WI) and T1-weighted contrast-enhancement images of preoperative MRI in 217 patients with pathologically diagnosed GBM. Patients were divided into negative and positive VEGF groups, with the latter group further subdivided into low and high expression. The machine learning models were established with the maximum relevance and minimum redundancy algorithm and the extreme gradient boosting classifier. The area under the receiver operating curve (AUC) and accuracy were calculated for the training and validation sets.

RESULTS

Positive VEGF in GBM was 63.1% (137/217), with a high expression ratio of 53.3% (73/137). To predict the positive and negative VEGF expression, 7 radiomic features were selected, with 3 features from T1CE and 4 from T2WI. The accuracy and AUC were 0.83 and 0.81, respectively, in the training set and were 0.73 and 0.74, respectively, in the validation set. To predict high and low levels, 7 radiomic features were selected, with 2 from T1CE, 1 from T2WI, and 4 from the data combinations of T1CE and T2WI. The accuracy and AUC were 0.88 and 0.88, respectively, in the training set and were 0.72 and 0.72, respectively, in the validation set.

CONCLUSION

The VEGF expression status in GBM can be predicted using a machine learning model. Radiomic features resulting from data combinations of different MRI sequences could be helpful.

A receptor-mediated landscape of druggable and targeted nanomaterials for gliomas

Gliomas are the most common type of brain cancer, and among them, glioblastoma multiforme (GBM) is the most prevalent (about 60% of cases) and the most aggressive type of primary brain tumor. The treatment of GBM is a major challenge due to the pathophysiological characteristics of the disease, such as the presence of the blood-brain barrier (BBB), which prevents and regulates the passage of substances from the bloodstream to the brain parenchyma, making many of the chemotherapeutics currently available not able to reach the brain in therapeutic concentrations, accumulating in non-target organs, and causing considerable adverse effects for the patient. In this scenario, nanocarriers emerge as tools capable of improving the brain bioavailability of chemotherapeutics, in addition to improving their biodistribution and enhancing their uptake in GBM cells. This is possible due to its nanometric size and surface modification strategies, which can actively target nanocarriers to elements overexpressed by GBM cells (such as transmembrane receptors) related to aggressive development, drug resistance, and poor prognosis. In this review, an overview of the most frequently overexpressed receptors in GBM cells and possible approaches to chemotherapeutic delivery and active targeting using nanocarriers will be presented.

Late-line treatment with bevacizumab alone or in combination with chemotherapy in recurrent high-grade gliomas

PURPOSE

Bevacizumab's use in recurrent high-grade glioma is controversial. This study evaluates outcomes in recurrent high-grade glioma patients receiving bevacizumab alone or combined with chemotherapy as a late-line treatment.

METHODS

We retrospectively analyzed patients treated with bevacizumab alone or combined with chemotherapy for high-grade gliomas who showed tumor progression after multiple treatment attempts. Overall survival (OS) and progression-free survival (PFS) were analyzed with Kaplan-Meier curves. Predictors of PFS according to prognostic variables were assessed with regression analysis.

RESULTS

Between 2010 and 2022, 31 consecutive patients received bevacizumab alone or combined with chemotherapy as a late-line treatment for recurrent high-grade gliomas. Of these patients, 14 (45.2%) were responders according to RANO criteria, and 17 (54.8%) showed progressive or stable disease. OS at 3, 6, and 12 months was 80.3%, 62.1%, and 43.5. PFS was 48.4%, 34.3%, and 21.8%, respectively. In the multivariate survival analysis, the only factor independently associated with PFS was smaller 2D tumor size in post-contrast T1-weighted MRI at bevacizumab initiation (p = 0.02). Median time-to-progression was 3 months (95%CI: 1-4) in the unmethylated MGMT promoter group and 6 (95%CI: 1-11) in the methylated MGMT promoter group. This difference was not statistically significant (p = 0.37).

CONCLUSIONS

Bevacizumab alone or in combination with chemotherapy could be beneficial as a late-line therapy in a subset of patients with recurrent high-grade glioma. Small 2D tumor size in post-contrast T1 weighted MRI at bevacizumab initiation was independently associated with prolonged time to progression.

DRAXIN as a Novel Diagnostic Marker to Predict the Poor Prognosis of Glioma Patients

An increasing number of evidences have shown that the carcinogenic effect of DRAXIN plays an important role in the malignant process of tumors, but the mechanism of its involvement in glioma has not yet been revealed. The main aim of this study is to explore the relationship between DRAXIN and the prognosis and pathogenesis of glioma through a large quality of data analysis. Firstly, thousands of tissue samples with clinical information were collected based on various public databases. Then, a series of bioinformatics analyses were performed to mine data from information of glioma samples extracted from several reputable databases to reveal the key role of DRAXIN in glioma development and progression, with the confirmation of basic experiments. Our results showed that high expression of the oncogene DRAXIN in tumor tissue and cells could be used as an independent risk factor for poor prognosis in glioma patients and was strongly associated with clinical risk features. The reverse transcription-quantitative PCR technique was then utilized to validate the DRAXIN expression results we obtained. In addition, co-expression analysis identified, respectively, top 10 genes that were closely associated with DRAXIN positively or negatively. Finally, in vitro experiments demonstrated that knockdown of DRAXIN significantly inhibited proliferation and invasion of glioma cell. To sum up, this is the first report of DRAXIN being highly expressed in gliomas and leading to poor prognosis of glioma patients. DRAXIN may not only benefit to explore the pathogenesis of gliomas, but also serve as a novel biological target for the treatment of glioma.

FRAT1 promotes the angiogenic properties of human glioblastoma cells via VEGFA

Glioblastoma is a common central nervous system tumor and despite considerable advancements in treatment patient prognosis remains poor. Angiogenesis is a significant prognostic factor in glioblastoma, anti‑angiogenic treatments represent a promising therapeutic approach. Vascular endothelial growth factor A (VEGFA) is a predominant regulator of angiogenesis and mounting evidence suggests that the Wnt signaling pathway serves a significant role in tumor angiogenesis. As a positive regulator of the Wnt/β‑catenin signaling pathway, frequently rearranged in advanced T‑cell lymphomas‑1 (FRAT1) is highly expressed in human glioblastoma and is significantly associated with glioblastoma growth, invasion and migration, as well as poor patient prognosis. Bioinformatics analysis demonstrated that both VEGFA and FRAT1 were highly expressed in most tumor tissues and associated with prognosis. However, whether and how FRAT1 is involved in angiogenesis remains to be elucidated. In the present study, the relationship between FRAT1 and VEGFA in angiogenesis was investigated using the human glioblastoma U251 cell line. Small interfering RNAs (siRNAs) were used to silence FRAT1 expression in U251 cells, and the mRNA and protein expression levels of VEGFA, as well as the concentration of VEGFA in U251 cell supernatants, were determined using reverse transcription‑quantitative PCR, western blotting and ELISA. A tube formation assay was conducted to assess angiogenesis. The results demonstrated that siRNA knockdown significantly decreased the protein expression levels of FRAT1 in U251 cells and markedly decreased the mRNA and protein expression levels of VEGFA. Furthermore, the concentration of VEGFA in the cell supernatant was significantly reduced and angiogenesis was suppressed. These results suggested that FRAT1 may promote VEGFA secretion and angiogenesis in human glioblastoma cells via the Wnt/β‑catenin signaling pathway, supporting the potential use of FRAT1 as a promising therapeutic target in human glioblastoma.

Cediranib, a pan-inhibitor of vascular endothelial growth factor receptors, inhibits proliferation and enhances therapeutic sensitivity in glioblastoma cells

AIMS

Glioblastoma (GB) is the most aggressive type of brain tumor. Rapid progression, active angiogenesis, and therapy resistance are major reasons for its high mortality. Elevated expression of members of the vascular endothelial growth factor (VEGF) family suggests that anti-VEGF therapies may be potent anti-glioma therapeutic approaches. Here, we evaluated the anti-tumor activity of cediranib, a pan inhibitor of the VEGF receptors, on GB cells.

MATERIALS AND METHODS

Anti-proliferative effects of cediranib were determined using MTT, crystal-violet staining, clonogenic and anoikis resistance assays. Apoptosis induction was assessed by Annexin V/PI staining and Western blot analysis and aggressive abilities of GB cells were investigated using cell migration/invasion assays and zymography. Small-interfering RNA (siRNA)-mediated Knockdown was used to study resistance mechanisms. The anti-proliferative and apoptotic effects of cediranib in combination with radiotherapy, temozolomide, bevacizumab were also evaluated using MTT, Annexin V/PI staining and Western blot analysis for cleaved PARP-1.

KEY FINDINGS

Cediranib reduced GB cell proliferation, induced apoptotic cell death and inhibited the aggressive abilities of GB cells. Cediranib synergistically increased the anti-proliferative and apoptotic effects of radiotherapy and bevacizumab and augmented the sensitivity of GB cells to temozolomide chemotherapy. In addition, knockdown of MET and AKT potentiated cediranib sensitivity in cediranib-resistant GB cells.

SIGNIFICANCE

These findings suggest that cediranib, alone or in combination with other therapeutics, is a promising strategy for the treatment of GB and provide a rationale for further investigation of the therapeutic potential of cediranib for the treatment of this fatal malignancy.

Glioma-Targeted Therapeutics: Computer-Aided Drug Design Prospective

Amongst the several types of brain cancers known to humankind, glioma is one of the most severe and life-threatening types of cancer, comprising 40% of all primary brain tumors. Recent reports have shown the incident rate of gliomas to be 6 per 100,000 individuals per year globally. Despite the various therapeutics used in the treatment of glioma, patient survival rate remains at a median of 15 months after undergoing first-line treatment including surgery, radiation, and chemotherapy with Temozolomide. As such, the discovery of newer and more effective therapeutic agents is imperative for patient survival rate. The advent of computer-aided drug design in the development of drug discovery has emerged as a powerful means to ascertain potential hit compounds with distinctively high therapeutic effectiveness against glioma. This review encompasses the recent advances of bio-computational in-silico modeling that have elicited the discovery of small molecule inhibitors and/or drugs against various therapeutic targets in glioma. The relevant information provided in this report will assist researchers, especially in the drug design domains, to develop more effective therapeutics against this global disease.

Multimodal Role of PACAP in Glioblastoma

Glioblastoma multiforme (GBM) is the deadliest form of brain tumors. To date, the GBM therapeutical approach consists of surgery, radiation-therapy and chemotherapy combined with molecules improving cancer responsiveness to treatments. In this review, we will present a brief overview of the GBM classification and pathogenesis, as well as the therapeutic approach currently used. Then, we will focus on the modulatory role exerted by pituitary adenylate cyclase-activating peptide, known as PACAP, on GBM malignancy. Specifically, we will describe PACAP ability to interfere with GBM cell proliferation, as well as the tumoral microenvironment. Considering its anti-oncogenic role in GBM, synthesis of PACAP agonist molecules may open new perspectives for combined therapy to existing gold standard treatment.

Hypoxia and EGF Stimulation Regulate VEGF Expression in Human Glioblastoma Multiforme (GBM) Cells by Differential Regulation of the PI3K/Rho-GTPase and MAPK Pathways

Glioblastoma multiforme (GBM) is one of the most common and deadly cancers of the central nervous system (CNS). It is characterized by the presence of hypoxic regions, especially in the core, leading to an increase in vascularity. This increased vascularization is driven by the expression of the major angiogenic inducer VEGF and the indirect angiogenic inducer Epidermal growth factor (EGF), which stimulates VEGF expression. In this study, we examine the regulation of VEGF by both hypoxia and the EGF signaling pathway. We also examine the involvement of pathways downstream from EGF signaling, including the mitogen-activated protein kinase/extracellular regulated kinase (MAPK/ERK) pathway and the Phosphatidylinositol-3-kinase/RhoA/C (PI3K/RhoA/C) pathway in this regulation. Our results show that VEGF expression and secretion levels increase following either hypoxia or EGF stimulation, with the two stimuli signaling in parallel. We also observed an increase in ERK and protein kinase B (Akt) phosphorylation, in response to EGF stimulation, with kinetics that correlated with the kinetics of the effect on VEGF. Using pharmacological inhibitors against ERK and PI3K and small interfering RNAs (siRNAs) against RhoA and RhoC, we found that both the ERK and the PI3K/RhoA/C pathways have to cooperate in order to lead to an increase in VEGF expression, downstream from EGF. In response to hypoxia, however, only ERK was involved in the regulation of VEGF. Hypoxia also led to a surprising decrease in the activation of PI3K and RhoA/C. Finally, the decrease in the activation of these Rho-GTPases was found to be mediated through a hypoxia-driven overexpression of the Rho-GTPase GTPase activating protein (GAP), StarD13. Therefore, while under normoxic conditions, EGF stimulates the activation of both the PI3K and the MAPK pathways and the induction of VEGF, in glioblastoma cells, hypoxic conditions lead to the suppression of the PI3K/RhoA/C pathway and an exclusive switch to the MAPK pathway.

Nanocomposites as biomolecules delivery agents in nanomedicine

Nanoparticles (NPs) are atomic clusters of crystalline or amorphous structure that possess unique physical and chemical properties associated with a size range of between 1 and 100 nm. Their nano-sized dimensions, which are in the same range as those of vital biomolecules, such as antibodies, membrane receptors, nucleic acids, and proteins, allow them to interact with different structures within living organisms. Because of these features, numerous nanoparticles are used in medicine as delivery agents for biomolecules. However, off-target drug delivery can cause serious side effects to normal tissues and organs. Considering this issue, it is essential to develop bioengineering strategies to significantly reduce systemic toxicity and improve therapeutic effect. In contrast to passive delivery, nanosystems enable to obtain enhanced therapeutic efficacy, decrease the possibility of drug resistance, and reduce side effects of "conventional" therapy in cancers. The present review provides an overview of the most recent (mostly last 3 years) achievements related to different biomolecules used to enable targeting capabilities of highly diverse nanoparticles. These include monoclonal antibodies, receptor-specific peptides or proteins, deoxyribonucleic acids, ribonucleic acids, [DNA/RNA] aptamers, and small molecules such as folates, and even vitamins or carbohydrates.

Arsenic Trioxide Suppressed Migration and Angiogenesis by Targeting FOXO3a in Gastric Cancer Cells

Arsenic trioxide (As₂O₃), a traditional remedy in Chinese medicine, has been used in acute promyelocytic leukemia (APL) research and clinical treatment. Previous studies have shown that As₂O₃ exerts its potent antitumor effects in solid tumors by regulating cell proliferation and survival. The aim of this study was to investigate whether As₂O₃ inhibited gastric cancer cell migration and angiogenesis by regulating FOXO3a expression. We found that As₂O₃ reduced gastric cancer cell viability in a dose-dependent manner and also inhibited cell migration and angiogenesis in vitro. Western blotting and immunofluorescence showed that As₂O₃ downregulated the levels of p-AKT, upregulated FOXO3a expression in the nucleus, and attenuated downstream Vascular endothelial growth factor (VEGF) and Matrix metallopeptidase 9 (MMP9) expression. Moreover, we demonstrated that knockdown of FOXO3a significantly reversed the inhibition of As₂O₃ and promoted cell migration and angiogenesis in vitro. Further, As₂O₃ significantly inhibited xenograft tumor growth and angiogenesis by upregulating FOXO3a expression in vivo. However, knockdown of FOXO3a attenuated the inhibitory effect of As₂O₃ in xenograft tumors, and increased microvessel density (MVD) and VEGF expression. Our results demonstrated that As₂O₃ inhibited migration and angiogenesis of gastric cancer cells by enhancing FOXO3a expression.

Isoprenaline/β2-AR activates Plexin-A1/VEGFR2 signals via VEGF secretion in gastric cancer cells to promote tumor angiogenesis

Background

The role of stress signals in regulating gastric cancer initiation and progression is not quite clear. It is known that stress signals modulate multiple processes such as immune function, cell migration and angiogenesis. However, few studies have investigated the mechanisms of how stress signals contribute to gastric cancer angiogenesis.

Methods

Here, we used β2-adrenergic receptor (β2-AR) agonist isoprenaline to imitate a stress signal and demonstrated the molecular mechanism underlying stress’s influence on tumor angiogenesis.

Results

We found that isoprenaline stimulated vascular endothelial growth factor (VEGF) secretion in gastric cancer cells and plexin-A1 expression was induced by human recombinant VEGF165 in both gastric cancer cells and vascular endothelial cells. Furthermore, interfere with plexin-A1 expression in gastric cancer cells influence HUVEC tube formation, migration and tumor growth in vivo.

Conclusions

These findings suggest that isoprenaline stimulate VGEF secretion and subsequently up-regulate the expression of plexin-A1 and VEGFR2 in gastric cancer cells, which form a positive impetus to promote tumor angiogenesis. This study reveals a novel molecular mechanism that a stress signal like isoprenaline may enhance angiogenesis via activating plexin-A1/VEGFR2 signaling pathway in gastric cancer, which may be a potential target in development of an anti-angiogenic therapy for gastric cancer.

Antitumour activity of 2-dihydroailanthone from the bark of Ailanthus altissima against U251

Context The bark of Ailanthus altissima (Mill.) Swingle (Simaroubaceae) is traditionally used to treat ascariasis, diarrhoea, spermatorrhoea, bleeding and gastrointestinal diseases. Objective The objective of this study is to investigate the antitumour activity and mechanism of 2-dihydroailanthone isolated from A. altissima. Materials and methods The U251 cells were treated with 1.00, 4.00 and 8.00 μg/mL of 2-dihydroailanthone for 48 h and the normal cells treated with 20.00 μg/mL of 2-dihydroailanthone were tested as well. Proliferation inhibition of 2-dihydroailanthone on the cells was tested by MTT. Apoptosis and cell-cycle distribution in U251 cells with 1.00, 3.00 and 5.80 μg/mL of 2-dihydroailanthone for 48 h were determined by flow cytometry, respectively. The expression of the apoptosis-related genes and proteins was analysed by RT-PCR and Western blot method, respectively. Results MTT assay revealed that 2-dihydroailanthone inhibited U251 cells proliferation. The cell viability of U251 cells was 62.82, 31.34 and 25.58%, and that of three normal cells was 72.75, 82.74 and 44.92%, respectively. Flow cytometry assay showed that 2-dihydroailanthone induced apoptosis and G0/G1 phase cycle arrest towards U251 cells. The late apoptotic cells were 11.37, 21.73 and 33.83%, and the cells cycle distributed in the G0/G1 accounted for 48.85, 62.77 and 64.40%, respectively. The Western blot and RT-PCR assay showed that up-regulation of pro-apoptotic bax protein and down-regulation of anti-apoptotic bcl-2 protein as well as their mRNA on U251 cells might be related to the apoptosis induction and proliferation inhibition. Conclusion An important bioactive component, 2-dihydroailanthone, has antitumour effects, enlightening a novel source of phytomedicines in tumour therapy.

Bevacizumab treatment for newly diagnosed glioblastoma: Systematic review and meta-analysis of clinical trials

High-grade glioma is a richly neovascularized brain solid tumor with a poor prognosis. Bevacizumab is a recombinant humanized monoclonal antibody that inhibits vascular endothelial cell proliferation and angiogenesis, which has shown clinical efficacy in recurrent glioblastoma. MEDLINE/PubMed, EMBASE and Web of Science databases were searched for relevant studies that compared bevacizumab plus combined radiotherapy/temozolomide (RT/TMZ) with RT/TMZ alone in newly diagnosed glioblastoma (GBM). Of all the studies identified, three comparative trials were included in the systematic review. All three enrolling trials, including a total of 1,738 patients, investigated bevacizumab or placebo plus combined RT/TMZ treatment in glioblastoma. The result showed no increased overall survival (OS) (pooled hazard ratio (HR), 1.04; 95% confidence interval (CI), 0.84-1.29; P=0.71) but increased progression-free survival (HR, 0.74; 95% CI, 0.62-0.88; P=0.0009). However, the two randomized double-blind placebo-control trials exemplified a high rate of adverse events of the bevacizumab compared with the placebo group while discrepant points were noted in term of quality-of-life outcome. Additionally, bevacizumab plus RT/TMZ did not increase the 6-month survival rate [odd ratios (ORs), 0.65; 95% CI, 0.37-1.13; P=0.13). Overall, addition of bevacizumab to radiotherapy-temozolomide treatment may be an effective therapy strategy for improving progression-free survival. OS and the 6-month survival rate was not prolonged and there was questionable efficacy of bevacizumab on the quality-of-life of glioblastoma patients, thus further clinical trials should be performed.

Cyclodextrin-based targeting strategies for tumor treatment

The efficacy and applicability of anticancer drugs are greatly restricted by severe systemic toxicities and drug resistance. Targeting drug delivery strategies have been developed to prevent the shortcomings of chemotherapy. Among various approaches to specifically target drug-loaded carrier systems to the required pathological sites, ligand-attached cyclodextrin-based targeting complexes are a promising drug delivery system, which is achieved mainly through specific molecular interactions between the drugs and cell surface receptors. The principal targeting tactics include conjugation of cyclodextrin with targeting moieties or encapsulation drugs in cyclodextrins. The cyclodextrin-based supramolecules, polymers, or nanoparticles bearing bioactive substances such as folate, estrogens, carbohydrates, peptides, etc. have been reviewed.

Current medical treatment of glioblastoma

Glioblastoma is the most common adult malignant primary brain tumor. Despite the advances in therapeutic options, survival of patients with glioblastoma remains dismal at 15-18 months. Current standard of care for newly diagnosed glioblastoma is maximal possible safe resection consistent with the preservation of neurologic function followed by concurrent temozolomide with radiation and adjuvant. Treatment options at recurrence include surgical resection with or without the placement of carmustine wafers, re-irradiation and chemotherapeutics such as nitrosoureas (lomustine, carmustine) or bevacizumab, a monoclonal antibody targeting vascular endothelial growth factor (VEGF).

Current standards and new concepts in MRI and PET response assessment of antiangiogenic therapies in high-grade glioma patients

Despite multimodal treatment, the prognosis of high-grade gliomas is grim. As tumor growth is critically dependent on new blood vessel formation, antiangiogenic treatment approaches offer an innovative treatment strategy. Bevacizumab, a humanized monoclonal antibody, has been in the spotlight of antiangiogenic approaches for several years. Currently, MRI including contrast-enhanced T1-weighted and T2/fluid-attenuated inversion recovery (FLAIR) images is routinely used to evaluate antiangiogenic treatment response (Response Assessment in Neuro-Oncology criteria). However, by restoring the blood-brain barrier, bevacizumab may reduce T1 contrast enhancement and T2/FLAIR hyperintensity, thereby obscuring the imaging-based detection of progression. The aim of this review is to highlight the recent role of imaging biomarkers from MR and PET imaging on measurement of disease progression and treatment effectiveness in antiangiogenic therapies. Based on the reviewed studies, multimodal imaging combining standard MRI with new physiological MRI techniques and metabolic PET imaging, in particular amino acid tracers, may have the ability to detect antiangiogenic drug susceptibility or resistance prior to morphological changes. As advances occur in the development of therapies that target specific biochemical or molecular pathways and alter tumor physiology in potentially predictable ways, the validation of physiological and metabolic imaging biomarkers will become increasingly important in the near future.

Novel paracrine modulation of Notch-DLL4 signaling by fibulin-3 promotes angiogenesis in high-grade gliomas

High-grade gliomas are characterized by exuberant vascularization, diffuse invasion, and significant chemoresistance, resulting in a recurrent phenotype that makes them impossible to eradicate in the long term. Targeting protumoral signals in the glioma microenvironment could have significant impact against tumor cells and the supporting niche that facilitates their growth. Fibulin-3 is a protein secreted by glioma cells, but absent in normal brain, that promotes tumor invasion and survival. We show here that fibulin-3 is a paracrine activator of Notch signaling in endothelial cells and promotes glioma angiogenesis. Fibulin-3 overexpression increased tumor VEGF levels, microvascular density, and vessel permeability, whereas fibulin-3 knockdown reduced vessel density in xenograft models of glioma. Fibulin-3 localization in human glioblastomas showed dense fiber-like condensations around tumor blood vessels, which were absent in normal brain, suggesting a remarkable association of this protein with tumor endothelium. At the cellular level, fibulin-3 enhanced endothelial cell motility and association to glioma cells, reduced endothelial cell sprouting, and increased formation of endothelial tubules in a VEGF-independent and Notch-dependent manner. Fibulin-3 increased ADAM10/17 activity in endothelial cells by inhibiting the metalloprotease inhibitor TIMP3; this resulted in increased Notch cleavage and increased expression of DLL4 independently of VEGF signaling. Inhibition of ADAM10/17 or knockdown of DLL4 reduced the proangiogenic effects of fibulin-3 in culture. Taken together, these results reveal a novel, proangiogenic role of fibulin-3 in gliomas, highlighting the relevance of this protein as an important molecular target in the tumor microenvironment.

Endothelial cells promote stem-like phenotype of glioma cells through activating the Hedgehog pathway

Microenvironmental regulation of cancer stem cells (CSCs) strongly influences the onset and spread of cancer. The way in which glioma cells interact with their microenvironment and acquire the phenotypes of CSCs remains elusive. We investigated how communication between vascular endothelial cells and glioma cells promoted the properties of glioma stem cells (GSCs). We observed that CD133⁺ GSCs were located closely to Shh⁺ endothelial cells in specimens of human glioblastoma multiforme (GBM). In both in vitro and in vivo studies, we found that endothelial cells promoted the appearance of CSC-like glioma cells, as demonstrated by increases in tumourigenicity and expression of stemness genes such as Sox2, Olig2, Bmi1 and CD133 in glioma cells that were co-cultured with endothelial cells. Knockdown of Smo in glioma cells led to a significant reduction of their CSC-like phenotype formation in vitro and in vivo. Endothelial cells with Shh knockdown failed to promote Hedgehog (HH) pathway activation and CSC-like phenotype formation in co-cultured glioma cells. By examination of glioma tissue specimens from 65 patients, we found that the survival of glioma patients was closely correlated with the expression of both Shh by endothelial cells and Gli1 by perivascular glioma cells. Taken together, our study demonstrates that endothelial cells in the tumour microenvironment provide Shh to activate the HH signalling pathway in glioma cells, thereby promoting GSC properties and glioma propagation. © 2014 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.

Levels of vascular endothelial growth factor and matrix metalloproteinase-9 proteins in patients with glioma

OBJECTIVE

To investigate the levels of vascular endothelial growth factor (VEGF) and matrix metalloproteinase-9 (MMP-9) proteins in patients with glioma, in order to determine if either protein has prognostic value.

METHOD

The presence of VEGF and MMP-9 proteins in paraffin-embedded tumour specimens from patients with glioma was detected using immunohistochemistry. The correlation between the levels of VEGF and MMP-9 proteins and tumour grade was analysed.

RESULTS

A total of 32 patients with low-grade gliomas (World Health Organization [WHO] grade II) and 48 patients with high-grade gliomas (WHO grades III-IV) participated in the study. Positive immunohistochemical staining of VEGF and MMP-9 proteins was detected in 58/80 (72.5%) and 60/80 (75.0%) of patients, respectively. The level of VEGF immunostaining was significantly positively correlated with the level of MMP-9 immunostaining (r = 0.78). Significantly more high-grade gliomas (grades III-IV) demonstrated positive VEGF and MMP-9 immunostaining compared with the low grade gliomas (grades I-II).

CONCLUSIONS

These data suggest that VEGF and MMP-9 play an important role in the malignant behaviour of gliomas.

Predictive value of tumor recurrence using urinary vascular endothelial factor levels in patients receiving radiation therapy for Glioblastoma Multiforme (GBM)

Background

Glioblastoma Multiforme (GBM) is the most common primary malignant tumor of the central nervous system. Standard of care includes maximal resection followed by chemoradiotherapy. Tumors need adequate perfusion and neovascularization to maintain oxygenation and for removal of wastes. Vascular endothelial growth factor (VEGF) is a well characterized pro-angiogenic factor. We hypothesized that the increases in urinary VEGF levels would occur early in the course of tumor recurrence or progression. We examine the feasibility of collecting and analyzing urinary VEGF levels in a prospective, multi-institutional trial (Radiation Therapy Oncology Group, RTOG, 0611) as well as the role of VEGF as a marker of tumor recurrence.

Method

We evaluated VEGF levels in urine specimens collected post-operatively, at the conclusion of radiation therapy (RT) and one month following RT. Urinary VEGF levels were correlated with tumor progression at one year. VEGF levels were measured by enzyme-linked immunosorbant assay in urine specimens and normalized to urinary creatinine levels. Sample size was determined based on a 50% 1-year recurrence rate. With a sensitivity and specificity of 80%, the expected 95% confidence interval was (0.69, 0.91) with 100 patients. A failure was defined as documented disease progression, recurrence or death before one year.

Results

202 patients were enrolled between February-2006 and October-2007. Four patients were ineligible as they did not receive RT. Of the remaining 198 patients, 128 had all three samples collected. In this group, 35 patients (27.3%) did not progress, 89 (69.5%) had progression and 4 (3.1%) died without evidence of progression. Median VEGF levels at baseline were 52.9 pg/mg Cr (range 0.2- 15,034.4); on the last day of RT, 56.6 (range 0–2,377.1); and at one month follow-up, 70.0 (range 0.1-1813.2). In patients without progression at 1-year, both baseline VEGF level and end of RT VEGF level were lower than those of patients who progressed: 40.3 (range 0.2-350.8) vs. 59.7 (range 1.3-15,034.4) and 41.8 (range 0–356.8) vs. 69.7 (range 0–2,377.1), respectively. This did not reach statistical significance. Comparison of the change in VEGF levels between the end of RT and one month following RT, demonstrated no significant difference in the proportions of progressors or non-progressors at 1-year for either the VEGF increased or VEGF decreased groups.

Conclusion

Urine can be collected and analyzed in a prospective, multi-institutional trial. In this study of patients with GBM a change in urinary VEGF levels between the last day of RT and the one month following RT did not predict for tumor progression by one year.

Pleiotropic effects of cancer cells' secreted factors on human stromal (mesenchymal) stem cells

Introduction

Studying cancer tumors’ microenvironment may reveal a novel role in driving cancer progression and metastasis. The biological interaction between stromal (mesenchymal) stem cells (MSCs) and cancer cells remains incompletely understood. Herein, we investigated the effects of tumor cells’ secreted factors as represented by a panel of human cancer cell lines (breast (MCF7 and MDA-MB-231); prostate (PC-3); lung (NCI-H522); colon (HT-29) and head & neck (FaDu)) on the biological characteristics of MSCs.

Methods

Morphological changes were assessed using fluorescence microscopy. Changes in gene expression were assessed using Agilent microarray and qRT-PCR. GeneSpring 12.1 and DAVID tools were used for bioinformatic and signaling pathway analyses. Cell migration was assessed using a transwell migration system. SB-431542, PF-573228 and PD98059 were used to inhibit transforming growth factor β (TGFβ), focal adhesion kinase (FAK), and mitogen activated protein kinase kinase (MAPKK) pathways, respectively. Interleukin-1β (IL1β) was measured using ELISA.

Results

MSCs exposed to secreted factors present in conditioned media (CM) from FaDu, MDA-MB-231, PC-3 and NCI-H522, but not from MCF7 and HT-29, developed an elongated, spindle-shaped morphology with bipolar processes. In association with phenotypic changes, genome-wide gene expression and bioinformatics analysis revealed an enhanced pro-inflammatory response of those MSCs. Pharmacological inhibitions of FAK and MAPKK severely impaired the pro-inflammatory response of MSCs to tumor CM (approximately 80% to 99%, and 55% to 88% inhibition, respectively), while inhibition of the TGFβ pathway was found to promote the pro-inflammatory response (approximately 3-fold increase). In addition, bioinformatics and pathway analysis of gene expression data from tumor cell lines combined with experimental validation revealed tumor-derived IL1β as one mediator of the pro-inflammatory phenotype observed in MSCs exposed to tumor CM.

MSCs exhibited significant tropism toward secreted factors from the aforementioned tumor cell lines, while both normal and MSCs exposed to tumor CM were capable of attracting human peripheral blood mononuclear cells (PBMCs).

Conclusions

Our data revealed tumor-derived IL1β as one mediator of the pro-inflammatory response in MSCs exposed to tumor CM, which was found to be positively regulated by FAK and MAPK signaling and negatively regulated by TGFβ signaling. Thus, our data support a model where MSCs could promote cancer progression through becoming pro-inflammatory cells within the cancer stroma.

Tumor cell-mediated neovascularization and lymphangiogenesis contrive tumor progression and cancer metastasis

Robust neovascularization and lymphangiogenesis have been found in a variety of aggressive and metastatic tumors. Endothelial sprouting angiogenesis is generally considered to be the major mechanism by which new vasculature forms in tumors. However, increasing evidence shows that tumor vasculature is not solely composed of endothelial cells (ECs). Some tumor cells acquire processes similar to embryonic vasculogenesis and produce new vasculature through vasculogenic mimicry, trans-differentiation of tumor cells into tumor ECs, and tumor cell-EC vascular co-option. In addition, tumor cells secrete various vasculogenic factors that induce sprouting angiogenesis and lymphangiogenesis. Vasculogenic tumor cells actively participate in the formation of vascular cancer stem cell niche and a premetastatic niche. Therefore, tumor cell-mediated neovascularization and lymphangiogenesis are closely associated with tumor progression, cancer metastasis, and poor prognosis. Vasculogenic tumor cells have emerged as key players in tumor neovascularization and lymphangiogenesis and play pivotal roles in tumor progression and cancer metastasis. However, the mechanisms underlying tumor cell-mediated vascularity as they relate to tumor progression and cancer metastasis remain unclear. Increasing data have shown that various intrinsic and extrinsic factors activate oncogenes and vasculogenic genes, enhance vasculogenic signaling pathways, and trigger tumor neovascularization and lymphangiogenesis. Collectively, tumor cells are the instigators of neovascularization. Therefore, targeting vasculogenic tumor cells, genes, and signaling pathways will open new avenues for anti-tumor vasculogenic and metastatic drug discovery. Dual targeting of endothelial sprouting angiogenesis and tumor cell-mediated neovascularization and lymphangiogenesis may overcome current clinical problems with anti-angiogenic therapy, resulting in significantly improved anti-angiogenesis and anti-cancer therapies.

Dihydroartemisinin inhibits tumor growth of human osteosarcoma cells by suppressing Wnt/β-catenin signaling

Osteosarcoma (OS) is the most common type of bone cancer. Even with early diagnosis and aggressive treatment, the prognosis for OS is poor. In the present study, we investigated the proliferation and invasion inhibitory effect of dihydroartemisinin (DHA) on human OS cells and the possible molecular mechanisms involved. We demonstrated that DHA can inhibit proliferation, decrease migration, reduce invasion and induce apoptosis in human OS cells. Using an in vivo tumor animal model, we confirmed that DHA can prevent OS formation and maintain intact bone structure in athymic mice. In addition, we examined the possible molecular mechanisms mediating the function of DHA. We found that the total protein levels and transcriptional activity of β-catenin in OS cells are reduced by DHA treatment, and this may result from the increased catalytic activity of glycogen synthase kinase 3β (GSK3β). Moreover, the inhibitory effect of DHA on OS cells is reversed by overexpression of β-catenin, but is further enhanced by knockdown of β-catenin, respectively. Collectively, our results reveal that DHA can inhibit tumor growth of OS cells by inactivating Wnt/β-catenin signaling. Therefore, DHA is a promising chemotherapy agent in the treatment of human OS.

VEGF promotes proliferation of human glioblastoma multiforme stem-like cells through VEGF receptor 2

Cancer stem-like cells, which have been described as tumor-initiating cells or tumor-propagating cells, play a crucial role in our fundamental understanding of glioblastoma multiforme (GBM) and its recurrence. GBM is a lethal cancer, characterized by florid vascularization and aberrantly elevated vascular endothelial growth factor (VEGF). VEGF promotes tumorigenesis and angiogenesis of human GBM stem-like cells (GBSCs). However, whether and how VEGF contributes to GBSCs proliferation remain largely uncertain. In this study, human GBSCs were isolated from surgical specimens of glioblastoma and cultured in medium favored for stem cell growth. Neural Colony-Forming Cell Assay and ATP assay were performed to measure GBSC proliferation under normoxia (20% O₂) and hypoxia (1% O₂). Our observations demonstrate that exogenous VEGF stimulates GBSC proliferation in a dose-dependent manner via VEGF Receptor 2 (VEGFR2); while VEGF Receptor 1 (VEGFR1) has a negative feedback effect on VEGFR2 when cells were exposed to higher concentration of VEGF. These results suggest that suppressing VEGFR2-dependent GBSC proliferation is a potentially therapeutic strategy in GBM.