Cell migration in paediatric glioma; characterisation and potential therapeutic targeting

Chlorin e6-Loaded Nanostructured Lipid Carriers Targeted by Angiopep-2: Advancing Photodynamic Therapy in Glioblastoma

Glioblastoma (GBM) is a highly aggressive brain tumor known for its resistance to standard treatments. Despite surgery being a primary option, it often leads to incomplete removal and high recurrence rates. Photodynamic therapy (PDT) holds promise as an adjunctive treatment, but safety concerns and the need for high-power lasers have limited its widespread use. This research addresses these challenges by introducing a novel PDT approach, using chlorin e6 (Ce6) enclosed in nanostructured lipid carriers (Ang-Ce6-NLCs) and targeted to GBM with the angiopep-2 peptide. Remarkably, a single 5-min irradiation session with LEDs at 660 nm and low power density (10 mW cm- 2) proves effective against GBM, while reducing safety risks associated with high-power lasers. Encapsulation improves Ce6 stability and performance in physiological environments, while angiopep-2 targeting enhances delivery to GBM cells, maximizing treatment efficacy and minimizing off-target effects. The findings demonstrate that Ang-Ce6-NLCs-mediated PDT brings about a significant reduction in GBM cell viability, increases oxidative stress, reduces tumor migration, and enhances apoptosis. Overall, such treatment holds potential as a safe and efficient intraoperative removal of GBM infiltrating cells that cannot be reached by surgery, using low-power LED light to minimize harm to surrounding healthy tissue while maximizing tumor treatment.

The Landscape of Pediatric High-Grade Gliomas: The Virtues and Pitfalls of Pre-Clinical Models

Pediatric high-grade gliomas (pHGG) are malignant and usually fatal central nervous system (CNS) WHO Grade 4 tumors. The majority of pHGG consist of diffuse midline gliomas (DMG), H3.3 or H3.1 K27 altered, or diffuse hemispheric gliomas (DHG) (H3.3 G34-mutant). Due to diffuse tumor infiltration of eloquent brain areas, especially for DMG, surgery has often been limited and chemotherapy has not been effective, leaving fractionated radiation to the involved field as the current standard of care. pHGG has only been classified as molecularly distinct from adult HGG since 2012 through Next-Generation sequencing approaches, which have shown pHGG to be epigenetically regulated and specific tumor sub-types to be representative of dysregulated differentiating cells. To translate discovery research into novel therapies, improved pre-clinical models that more adequately represent the tumor biology of pHGG are required. This review will summarize the molecular characteristics of different pHGG sub-types, with a specific focus on histone K27M mutations and the dysregulated gene expression profiles arising from these mutations. Current and emerging pre-clinical models for pHGG will be discussed, including commonly used patient-derived cell lines and in vivo modeling techniques, encompassing patient-derived xenograft murine models and genetically engineered mouse models (GEMMs). Lastly, emerging techniques to model CNS tumors within a human brain environment using brain organoids through co-culture will be explored. As models that more reliably represent pHGG continue to be developed, targetable biological and genetic vulnerabilities in the disease will be more rapidly identified, leading to better treatments and improved clinical outcomes.

Traditional Plant-Derived Compounds Inhibit Cell Migration and Induce Novel Cytoskeletal Effects in Glioblastoma Cells

Glioblastomas (GBMs) are aggressive and invasive cancers of the brain, associated with high rates of tumour recurrence and poor patient outcomes despite initial treatment. Targeting cell migration is therefore of interest in highly invasive cancers such as GBMs, to prevent tumour dissemination and regrowth. One current aim of GBM research focuses on assessing the anti-migratory properties of novel or repurposed inhibitors, including plant-based drugs which display anti-cancer properties. We investigated the potential anti-migratory activity of plant-based products with known cytotoxic effects in cancers, using a range of two-dimensional (2D) and three-dimensional (3D) migration and invasion assays as well as immunofluorescence microscopy to determine the specific anti-migratory and phenotypic effects of three plant-derived compounds, Turmeric, Indigo and Magnolia bark, on established glioma cell lines. Migrastatic activity was observed in all three drugs, with Turmeric exerting the most inhibitory effect on GBM cell migration into scratches and from the spheroid edge at all the timepoints investigated (p < 0.001). We also observed novel cytoskeletal phenotypes affecting actin and the focal adhesion dynamics. As our in vitro results determined that Turmeric, Indigo and Magnolia are promising migrastatic drugs, we suggest additional experimentation at the whole organism level to further validate these novel findings.

Microtubule-Targeting Combined with HDAC Inhibition Is a Novel Therapeutic Strategy for Diffuse Intrinsic Pontine Gliomas

Diffuse intrinsic pontine gliomas (DIPG) are an incurable childhood brain cancer for which novel treatments are needed. DIPGs are characterized by a mutation in the H3 histone (H3K27M), resulting in loss of H3K27 methylation and global gene dysregulation. TRX-E-009-1 is a novel anticancer agent with preclinical activity demonstrated against a range of cancers. We examined the antitumor activity of TRX-E-009-1 against DIPG neurosphere cultures and observed tumor-specific activity with IC50s ranging from 20 to 100 nmol/L, whereas no activity was observed against normal human astrocyte cells. TRX-E-009-1 exerted its anti-proliferative effect through the induction of apoptotic pathways, with marked increases in cleaved caspase 3 and cleaved PARP levels, while also restoring histone H3K27me3 methylation. Co-administration of TRX-E-009-1 and the histone deacetylase (HDAC) inhibitor SAHA extended survival in DIPG orthotopic animal models. This antitumor effect was further enhanced with irradiation. Our findings indicate that TRX-E-009-1, combined with HDAC inhibition, represents a novel, potent therapy for children with DIPG.

Culturing and Imaging Glioma Stem Cells in 3D Collagen Matrices

Methods to maintain human glioma stem cells as neurosphere cultures and image their dynamic behavior in 3D collagen matrices are described. Additional approaches to monitor glioma stem cell differentiation into mesenchymal-type cells, along with example data are included. Together, these approaches enable glioma stem cell differentiation to be controlled while maintaining the cells in culture, as well as allowing cell dynamics to be captured and analyzed. These methods should be helpful for those seeking to understand the molecular mechanisms driving the invasion of glioma cells through three-dimensional environments. © 2023 Wiley Periodicals LLC. Basic Protocol 1: Culturing human glioma stem cells as neurospheres Basic Protocol 2: Inducing GSC adherence and monitoring their differentiation into mesenchymal cells Support Protocol 1: Preparing fibronectin-coated dishes for cell microscopy Basic Protocol 3: Embedding GSCs in a 3D collagen matrix to study their invasive behavior Support Protocol 2: Phase-contrast imaging with a tiled matrix to study cell migration in a 3D gel.

VRK1 as a synthetic lethal target in VRK2 promoter-methylated cancers of the nervous system

Collateral lethality occurs when loss of a gene/protein renders cancer cells dependent on its remaining paralog. Combining genome-scale CRISPR/Cas9 loss-of-function screens with RNA sequencing in over 900 cancer cell lines, we found that cancers of nervous system lineage, including adult and pediatric gliomas and neuroblastomas, required the nuclear kinase vaccinia-related kinase 1 (VRK1) for their survival in vivo. VRK1 dependency was inversely correlated with expression of its paralog VRK2. VRK2 knockout sensitized cells to VRK1 loss, and conversely, VRK2 overexpression increased cell fitness in the setting of VRK1 loss. DNA methylation of the VRK2 promoter was associated with low VRK2 expression in human neuroblastomas and adult and pediatric gliomas. Mechanistically, depletion of VRK1 reduced barrier-to-autointegration factor phosphorylation during mitosis, resulting in DNA damage and apoptosis. Together, these studies identify VRK1 as a synthetic lethal target in VRK2 promoter-methylated adult and pediatric gliomas and neuroblastomas.

Lithium chloride inhibits the migration and invasion of osteosarcoma cells by blocking nuclear translocation of phospho-Erk

Lithium chloride (LiCl) is an important mood-stabilizing therapeutic agent for bipolar disorders, which has also been shown to inhibit cancer cell metastasis. Investigations of LiCl-induced signaling have focused mainly on extracellular signal regulated kinase 1/2 (ERK1/2) and glycogen synthase kinase 3 (GSK-3). However, little is known about the differences in cellular activities resulting from specific signaling via each of these pathways. In this study, we investigated the difference in responses between the Wnt/β-catenin and ERK pathways by LiCl or epidermal growth factor (EGF) treatment of osteosarcoma cells. In particular, we analyzed the mechanisms responsible for differences in cell mobility and cell proliferation when pERK or β-catenin is activated. In osteosarcoma cells treated with LiCl or EGF, active β-catenin and p-ERK protein levels were significantly increased compared to those in the control group. However, in wound healing and transwell invasion assays, U2OS and SaOS2 cell migration was significantly reduced by LiCl treatment but increased by EGF treatment. In addition, the proliferation of U2OS cells was reduced by LiCl treatment but increased by EGF treatment. Using immunofluorescence microscopy, we observed nuclear accumulation of phosphorylated ERK (pERK) with EGF treatment, but pERK was restricted to the perinuclear area with LiCl treatment. These results were confirmed using immunoblot assays after subcellular fractionation. Together, these data suggest that LiCl interferes with the translocation of pERK from the cytoplasm to the nucleus.

GSK-3 Inhibition Is Cytotoxic in Glioma Stem Cells through Centrosome Destabilization and Enhances the Effect of Radiotherapy in Orthotopic Models

BACKGROUND

Previous data on glycogen synthase kinase 3 (GSK-3) inhibition in cancer models support a cytotoxic effect with selectivity for tumor cells compared to normal tissue but the effect of these inhibitors in glioma has not been widely studied. Here, we investigate their potential as cytotoxics in glioma.

METHODS

We assessed the effect of pharmacologic GSK-3 inhibition on established (U87, U251) and patient-derived (GBM1, GBM4) glioblastoma (GBM) cell lines using cytotoxicity assays as well as undertaking a detailed investigation of the effect on cell cycle, mitosis, and centrosome biology. We also assessed drug uptake and efficacy of GSK-3 inhibition alone and in combination with radiation in xenograft models.

RESULTS

Using the selective GSK-3 inhibitor AZD2858, we demonstrated single agent cytotoxicity in two patient-derived glioma cell lines (GBM1, GBM4) and two established cell lines (U251 and U87) with IC50 in the low micromolar range promoting centrosome disruption, failed mitosis, and S-phase arrest. Glioma xenografts exposed to AZD2858 also showed growth delay compared to untreated controls. Combined treatment with radiation increased the cytotoxic effect of clinical radiation doses in vitro and in orthotopic glioma xenografts.

CONCLUSIONS

These data suggest that GSK-3 inhibition promotes cell death in glioma through disrupting centrosome function and promoting mitotic failure and that AZD2858 is an effective adjuvant to radiation at clinical doses.

Neuroblastoma and DIPG Organoid Coculture System for Personalized Assessment of Novel Anticancer Immunotherapies

Cancer immunotherapy has transformed the landscape of adult cancer treatment and holds a great promise to treat paediatric malignancies. However, in vitro test coculture systems to evaluate the efficacy of immunotherapies on representative paediatric tumour models are lacking. Here, we describe a detailed procedure for the establishment of an ex vivo test coculture system of paediatric tumour organoids and immune cells that enables assessment of different immunotherapy approaches in paediatric tumour organoids. We provide a step-by-step protocol for an efficient generation of patient-derived diffuse intrinsic pontine glioma (DIPG) and neuroblastoma organoids stably expressing eGFP-ffLuc transgenes using defined serum-free medium. In contrast to the chromium-release assay, the new platform allows for visualization, monitoring and robust quantification of tumour organoid cell cytotoxicity using a non-radioactive assay in real-time. To evaluate the utility of this system for drug testing in the paediatric immuno-oncology field, we tested our in vitro assay using a clinically used immunotherapy strategy for children with high-risk neuroblastoma, dinutuximab (anti-GD2 monoclonal antibody), on GD2 proficient and deficient patient-derived neuroblastoma organoids. We demonstrated the feasibility and sensitivity of our ex vivo coculture system using human immune cells and paediatric tumour organoids as ex vivo tumour models. Our study provides a novel platform for personalized testing of potential anticancer immunotherapies for aggressive paediatric cancers such as neuroblastoma and DIPG.

Anticancer potential of indirubins in medicinal chemistry: Biological activity, structural modification, and structure-activity relationship

Indirubin is the crucial ingredient of Danggui Longhui Wan and Qing-Dai, traditional Chinese medicine herbal formulas used for the therapy of chronic myelocytic leukemia in China for hundreds of years. Although the monomeric indirubin has been used in China for the treatment human chronic myelocytic leukemia. However, due to low water solubility, poor pharmacokinetic properties and low therapeutic effects are the major obstacle, and had significantly limited its clinical application. Consequently, the attractive anticancer profile of indirubin has enthused numerous researchers to discover novel indirubin derivatives with improved pharmacodynamic activity as well as good pharmacokinetic property. In this paper, we comprehensively review the recent progress of anticancer potential of indirubins, structural modification and structure-activity relationship, which may provide useful direction for the further development of novel indirubins with improved pharmacological profiles for the treatment of various types of cancer.

[The art of war as applied to pediatric gliomas: Know your enemy]

Pediatric brain cancers represent the most frequent solid tumors and the leading cause of cancer-driven mortality in children. Pediatric High Grade Gliomas display a very poor prognosis. Among these, DIPG (Diffuse Intrinsic Pontine Gliomas), localized to the brain stem, cannot benefit from a total exeresis due to this critical location and to their highly infiltrating nature. Radiotherapy remains the standard treatment against these tumors for almost five decades, and attempts to improve the prognosis of patients with chemotherapy or targeted therapies have failed. Thanks to the rise of high throughput sequencing, the knowledge of molecular alterations in pediatric gliomas strongly progressed and allowed to highlight distinct biomolecular entities and to establish more accurate diagnoses. In this review, we summarize this new information and the perspectives that it brings for clinical strategies.

Lithium treatment reverses irradiation-induced changes in rodent neural progenitors and rescues cognition

Cranial radiotherapy in children has detrimental effects on cognition, mood, and social competence in young cancer survivors. Treatments harnessing hippocampal neurogenesis are currently of great relevance in this context. Lithium, a well-known mood stabilizer, has both neuroprotective, pro-neurogenic as well as antitumor effects, and in the current study we introduced lithium treatment 4 weeks after irradiation. Female mice received a single 4 Gy whole-brain radiation dose on postnatal day (PND) 21 and were randomized to 0.24% Li2CO₃ chow or normal chow from PND 49 to 77. Hippocampal neurogenesis was assessed on PND 77, 91, and 105. We found that lithium treatment had a pro-proliferative effect on neural progenitors, but neuronal integration occurred only after it was discontinued. Also, the treatment ameliorated deficits in spatial learning and memory retention observed in irradiated mice. Gene expression profiling and DNA methylation analysis identified two novel factors related to the observed effects, Tppp, associated with microtubule stabilization, and GAD2/65, associated with neuronal signaling. Our results show that lithium treatment reverses irradiation-induced loss of hippocampal neurogenesis and cognitive impairment even when introduced long after the injury. We propose that lithium treatment should be intermittent in order to first make neural progenitors proliferate and then, upon discontinuation, allow them to differentiate. Our findings suggest that pharmacological treatment of cognitive so-called late effects in childhood cancer survivors is possible.

Invaders Exposed: Understanding and Targeting Tumor Cell Invasion in Diffuse Intrinsic Pontine Glioma

Diffuse Intrinsic Pontine Glioma (DIPG) is a rare, highly aggressive pediatric brain tumor that originates in the pons. DIPG is untreatable and universally fatal, with a median life expectancy of less than a year. Resection is not an option, due to the anatomical location of the tumor, radiotherapy has limited effect and no chemotherapeutic or targeted treatment approach has proven to be successful. This poor prognosis is partly attributed to the tumor's highly infiltrative diffuse and invasive spread. Thus, targeting the invasive behavior of DIPG has the potential to be of therapeutic value. In order to target DIPG invasion successfully, detailed mechanistic knowledge on the underlying drivers is required. Here, we review both DIPG tumor cell's intrinsic molecular processes and extrinsic environmental factors contributing to DIPG invasion. Importantly, DIPG represents a heterogenous disease and through advances in whole-genome sequencing, different subtypes of disease based on underlying driver mutations are now being recognized. Recent evidence also demonstrates intra-tumor heterogeneity in terms of invasiveness and implies that highly infiltrative tumor subclones can enhance the migratory behavior of neighboring cells. This might partially be mediated by “tumor microtubes,” long membranous extensions through which tumor cells connect and communicate, as well as through the secretion of extracellular vesicles. Some of the described processes involved in invasion are already being targeted in clinical trials. However, more research into the mechanisms of DIPG invasion is urgently needed and might result in the development of an effective therapy for children suffering from this devastating disease. We discuss the implications of newly discovered invasive mechanisms for therapeutic targeting and the challenges therapy development face in light of disease in the developing brain.

Indirubin 3'-Oxime Inhibits Migration, Invasion, and Metastasis InVivo in Mice Bearing Spontaneously Occurring Pancreatic Cancer via Blocking the RAF/ERK, AKT, and SAPK/JNK Pathways

BACKGROUND

Pancreatic ductal adenocarcinoma (PDAC) is an aggressive cancer with high invasive and metastatic potential. We generated a spontaneous PDAC mouse model and examined the therapeutic potential of indirubin 3'-oxime (Indox) against PDAC bearing mouse in vivo.

METHODS

Randomized 3-month-old LSL-Kras^G12D/+;Trp53^flox/+;Pdx-1-cre (KPC^flox) mice were intraperitoneally injected with 40 mg/kg Indox (n = 9) or a vehicle (n = 10) twice a week. At the end point, tumor status including proliferation, direct invasion, and distant metastasis was analyzed histopathologically. The inhibitory potentials of Indox for proliferation, migration/invasion, and the phosphorylation of target molecules were determined in KPC^flox-derived PDAC cells in vitro.

RESULTS

Prolonged survival by Indox via intraperitoneal administration was observed in the KPC^flox mice. Indox inhibited tumor proliferation accompanied with low levels of nuclear phosphorylated cyclin-dependent kinase (p-CDK) and cyclin B1 in vivo. Furthermore, Indox inhibited the migration/invasive activities of PDAC via down-regulation of matrix metalloproteinase (MMP)-9 in vitro and in vivo. Antibody array and immunoblotting analysis revealed that Indox inhibited the phosphorylation of multiple molecules, including key upstream proteins of MMP-9 in RAF/extracellular signal-regulated kinase (ERK), AKT, and stress-activated protein kinase/c-Jun-N-terminal kinase (SAPK/JNK) pathways.

CONCLUSION

Indox inhibited the proliferative, invasive, and metastatic potentials of PDAC in vitro and in vivo. Therefore, Indox could a therapeutic candidate for treating spontaneously occurring PDAC via blocking the RAF/ERK, AKT and SAPK/JNK pathways.

FGFR1 Expression and Role in Migration in Low and High Grade Pediatric Gliomas

The heterogeneous and invasive nature of pediatric gliomas poses significant treatment challenges, highlighting the importance of identifying novel chemotherapeutic targets. Recently, recurrent Fibroblast growth factor receptor 1 (FGFR1) mutations in pediatric gliomas have been reported. Here, we explored the clinical relevance of FGFR1 expression, cell migration in low and high grade pediatric gliomas and the role of FGFR1 in cell migration/invasion as a potential chemotherapeutic target. A high density tissue microarray (TMA) was used to investigate associations between FGFR1 and activated phosphorylated FGFR1 (pFGFR1) expression and various clinicopathologic parameters. Expression of FGFR1 and pFGFR1 were measured by immunofluorescence and by immunohistochemistry (IHC) in 3D spheroids in five rare patient-derived pediatric low-grade glioma (pLGG) and two established high-grade glioma (pHGG) cell lines. Two-dimensional (2D) and three-dimensional (3D) migration assays were performed for migration and inhibitor studies with three FGFR1 inhibitors. High FGFR1 expression was associated with age, malignancy, tumor location and tumor grade among astrocytomas. Membranous pFGFR1 was associated with malignancy and tumor grade. All glioma cell lines exhibited varying levels of FGFR1 and pFGFR1 expression and migratory phenotypes. There were significant anti-migratory effects on the pHGG cell lines with inhibitor treatment and anti-migratory or pro-migratory responses to FGFR1 inhibition in the pLGGs. Our findings support further research to target FGFR1 signaling in pediatric gliomas.

Indirubin-3'-oxime suppresses human cholangiocarcinoma through cell-cycle arrest and apoptosis

Cholangiocarcinoma (CCA) is one of the most serious of all cancers and a major public health problem. CCA is an extremely invasive cancer, and the survival rate for CCA patients is only 24 months after diagnosis. Although surgery and chemotherapy can extend the survival rate to 5 years, < 20-40% of CCA patients will survive this long; therefore, it is crucial to discover an effective chemotherapeutic agent for CCA. Indirubin-3'-oxime (I3O), a derivative of indirubin, has been shown to suppress cell proliferation and induce cell-cycle arrest and cell apoptosis in various human cancers. In this study, four human CCA cell lines-NOZ, HuCCT1, OCUG-1, and OZ-were used to evaluate the anticancer properties of I3O. Cell viability, cell-cycle arrest, and apoptosis were assessed using Western blotting, immunofluorescence, and flow cytometry analysis. The data show that I3O treatment can inhibit cell proliferation and induce cell-cycle arrest, and caspase-dependent apoptosis in CCA cells. These findings suggest that I3O could suppress tumor growth by regulating the cell cycle and inducing apoptosis, and is a potential therapeutic agent for treating human CCA.

Characterisation of mesenchymal colon tumour-derived cells in tumourspheres as a model for colorectal cancer progression

Cellular plasticity, the ability of cells to switch from an epitheial phenotype to a mesenchymal one and vice versa, plays a crucial role in tumour progression and metastases development. In 20-25% of patients with colon cancer and in 18% of patients with rectal cancer, metastases are present at the time of the first diagnosis. They are the first cause of colorectal cancer (CRC)-related mortality, defining stage IV CRC, which is characterized by a relatively short overall survival. We previously isolated two primary colon adenocarcinoma cell cultures that had undergone epithelial-mesenchymal transition (EMT), one with a high microsatellite instability phenotype (T88) and one with a chromosomal instability phenotype (T93). The aim of this study was to establish a model with which to study EMT, stemness features and cell plasticity in cancer progression and to examine the effects of incubation with lithium chloride (LiCl), a specific glycogen synthase kinase 3 β (GSK-3β) inhibitor, on these cellular processes. Indeed, GSK3β is an important regulator of cell survival, which promotes tumourigenesis in colon cells by facilitating the crosstalk between colorectal cancer pathways. Thus, we further characterized our system of adherent primary mesenchymal colon cancer cells and their paired tumourspheres by examining the expression and localisation of a panel of markers, including E- and N‑cadherin, CD133, CD44v6, aldehyde dehydrogenase 1 (ALDH1) and leucine-rich repeat‑containing G-protein coupled receptor 5 (LGR5). We also characterised the molecular features of these tumourspheres and examined their response to LiCl. Furthermore, we explored the effects of LiCl on cell motility and plasticity. We demonstrated that LiCl reduced cell migration, stemness features and cell plasticity. We also observed the atypical nuclear localisation of membrane proteins, including N‑cadherin, CD133 and CD44v6 in mesenchymal tumour cells. Of note, CD133 and CD44v6 appeared to localise at the plasma membrane in cells with a more epithelial phenotype, suggesting that the cytoplasmic/nuclear localisation of these proteins could favour and characterize cell plasticity in colorectal cancer progression.

Identification of antipsychotic drug fluspirilene as a potential anti-glioma stem cell drug

Glioma stem cell (GSC)-targeted therapy is expected to be one of the most innovative approaches to treat patients with glioblastoma (GBM). A number of the drugs that restrain the signaling pathway essential for GSC maintenance have been under clinical trials. Here, we identified fluspirilene, a traditional antipsychotic drug, as a GSC-targeting agent, selected from thousands of existing drugs, and investigated its therapeutic effects against GBM with the purpose of drug repositioning. To develop novel therapeutics targeting GSCs, we initially screened drug libraries for small-molecule compounds showing a greater efficacy, compared to that of controls, in inhibiting the proliferation and survival of different GSC lines using cell proliferation assay. Drugs already reported to show therapeutic effects against GBM or those under clinical trials were excluded from subsequent screening. Finally, we found three drugs showing remarkable antiproliferative effects on GSCs at low concentrations and investigated their therapeutic effects on GSCs, glioma cell lines, and in a GBM mouse model. Of the three compounds, fluspirilene demonstrated a significant inhibitory effect on the proliferation and invasion of glioma cells as well as in the model mice treated with the drug. These effects were associated with the inactivation of the signal transducer and activator of transcription 3 (STAT3). Redeveloping of fluspirilene is a promising approach for the treatment of GBM.

Oncolytic Herpes Simplex Virus Inhibits Pediatric Brain Tumor Migration and Invasion

Pediatric high-grade glioma (pHGG) and diffuse intrinsic pontine glioma (DIPG) are invasive tumors with poor survival. Oncolytic virotherapy, initially devised as a direct cytotoxic treatment, is now also known to act via immune-mediated mechanisms. Here we investigate a previously unreported mechanism of action: the inhibition of migration and invasion in pediatric brain tumors. We evaluated the effect of oncolytic herpes simplex virus 1716 (HSV1716) on the migration and invasion of pHGG and DIPG both in vitro using 2D (scratch assay, live cell imaging) and 3D (spheroid invasion in collagen) assays and in vivo using an orthotopic xenograft model of DIPG invasion. HSV1716 inhibited migration and invasion in pHGG and DIPG cell lines. pHGG cells demonstrated reduced velocity and changed morphology in the presence of virus. HSV1716 altered pHGG cytoskeletal dynamics by stabilizing microtubules, inhibiting glycogen synthase kinase-3, and preventing localized clustering of adenomatous polyposis coli (APC) to the leading edge of cells. HSV1716 treatment also reduced tumor infiltration in a mouse orthotopic xenograft DIPG model. Our results demonstrate that HSV1716 targets the migration and invasion of pHGG and DIPG and indicates the potential of an oncolytic virus (OV) to be used as a novel anti-invasive treatment strategy for pediatric brain tumors.

Targeting Gliomas: Can a New Alkylating Hybrid Compound Make a Difference?

Glioblastoma (GBM) is the most common and aggressive type of brain tumor in adults. The triazene Temozolomide (TMZ), an alkylating drug, is the classical chemotherapeutic agent for gliomas, but has been disappointing against the highly invasive and resistant nature of GBM. Hybrid compounds may open new horizons within this challenge. The multicomponent therapeutic strategy here used resides on a combination of two repurposing drugs acting by different but potentially synergistic mechanisms, improved efficacy, and lower resistance effects. We synthesized a new hybrid compound (HYBCOM) by covalently binding a TMZ analogue to valproic acid, a histone deacetylase inhibitor drug that was shown to sensitize TMZ-resistant glioma cells. Advantages of this new molecule as compared to TMZ, in terms of chemotherapeutic efficacy, were investigated. Our results evidenced that HYBCOM more efficiently decreased the viability and proliferation of the GL261 glioma cells, while showing to better target the tumor cells than the functionally normal astrocytes. Increased cytotoxicity by HYBCOM may be a consequence of the improved autophagic process observed. Additionally, HYBCOM changed the morphology of GL261 cells into a nonpolar, more rounded shape, impairing cell migration ability. Most interesting, and in opposite to TMZ, cells exposed to HYBCOM did not enhance the expression of drug resistance proteins, a major issue in the treatment of GBM. Overall, our studies indicate that HYBCOM has promising chemotherapeutic benefits over the classical TMZ, and future studies should assess if the treatment translates into efficacy in glioblastoma experimental models and reveal clinical benefits in GBM patients.

DIPG in Children - What Can We Learn from the Past?

Brainstem tumors represent 10–15% of pediatric central nervous system tumors and diffuse intrinsic pontine glioma (DIPG) is the most common brainstem tumor of childhood. DIPG is almost uniformly fatal and is the leading cause of brain tumor-related death in children. To date, radiation therapy (RT) is the only form of treatment that offers a transient benefit in DIPG. Chemotherapeutic strategies including multi-agent neoadjuvant chemotherapy, concurrent chemotherapy with RT, and adjuvant chemotherapy have not provided any survival advantage. To overcome the restrictive ability of the intact blood–brain barrier (BBB) in DIPG, several alternative drug delivery strategies have been proposed but have met with minimal success. Targeted therapies either alone or in combination with RT have also not improved survival. Five decades of unsuccessful therapies coupled with recent advances in the genetics and biology of DIPG have taught us several important lessons (1). DIPG is a heterogeneous group of tumors that are biologically distinct from other pediatric and adult high grade gliomas (HGG). Adapting chemotherapy and targeted therapies that are used in pediatric or adult HGG for the treatment of DIPG should be abandoned (2). Biopsy of DIPG is relatively safe and informative and should be considered in the context of multicenter clinical trials (3). DIPG probably represents a whole brain disease so regular neuraxis imaging is important at diagnosis and during therapy (4). BBB permeability is of major concern in DIPG and overcoming this barrier may ensure that drugs reach the tumor (5). Recent development of DIPG tumor models should help us accurately identify and validate therapeutic targets and small molecule inhibitors in the treatment of this deadly tumor.

Indirubin and Indirubin Derivatives for Counteracting Proliferative Diseases

Indirubin is the active component of Danggui Longhui Wan, a traditional Chinese medicine formulation. The encouraging clinical results from the 1980s obtained in chronic myelocytic leukemia patients treated with indirubin stimulated numerous studies on this compound. These investigations explored the use of indirubin in different types of cancer and reported the synthesis of novel derivatives with improved chemical and pharmacokinetic properties. In this paper, we review the impressive progress that has been made in elucidating the mechanistic understanding of how indirubin and its derivatives affect physiological and pathophysiological processes, mainly by inhibition of cell proliferation and induction of cell death. Furthermore, we survey the therapeutic use of these compounds in combating proliferative diseases such as cancer, restenosis, and psoriasis.

High-content analysis of tumour cell invasion in three-dimensional spheroid assays

Targeting infiltrating tumour cells is an attractive way of combating cancer invasion and metastasis. Here we describe a novel and reproducible method for high content analysis of invading cells using multicellular tumour spheroid assays in a high grade glioma model. Live cell imaging of spheroids generated from glioma cell lines, U87 and U251, gave insight into migration dynamics and cell morphology in response to anti-migratory drugs. Immunofluorescence imaging confirmed cytoskeletal rearrangements in the treated cells indicating a direct effect on cell morphology. Effect on migration was determined by a Migration Index (MI) from brightfield images which confirmed anti-migratory activity of the drugs. A marked effect on the core with treatment suggestive of disordered proliferation was also observed. A newly developed technique to prepare the spheroids and migratory cells for immunohistochemistry allowed an assessment of response to drug treatment with a selection of markers. A difference in protein expression was noted between cells maintained within the core and migratory cells indicative of the presence of cell subpopulations within the spheroid core. We conclude that this high content analysis allows researchers to perform screening of anti-tumour invasion compounds and study their effects on cellular dynamics, particularly in relation to protein expression, for the first time.