Atypical teratoid/rhabdoid tumors (AT/RT) are highly aggressive, malignant tumors and are the most common malignant brain tumor in children under 6 months of age. Currently, there is no standard treatment for AT/RT. Recent studies have reported potential anti-tumoral properties of ribavirin, a guanosine analog and anti-viral molecule approved by the Food and Drug Administration for treatment of hepatitis C. We previously demonstrated that ribavirin inhibited glioma cell growth in vitro and in vivo. Based on these results and the fact that no pre-clinical model of ribavirin in AT/RT exists, we decided to investigate the effect of ribavirin on several human AT/RT cell lines (BT12, BT16, and BT37) both in vitro and in vivo. We provide evidence that ribavirin has a significant impact on AT/RT cell growth and increases cell cycle arrest and cell death, potentially through modulation of the eIF4E and/or EZH2 pathways. Interestingly, using scratch wound and transwell Boyden chamber assays, we observed that ribavirin also impairs AT/RT cell migration, invasion, and adhesion. Finally, we demonstrate that ribavirin significantly improves the survival of mice orthotopically implanted with BT12 cells. Our work establishes that ribavirin is effective against AT/RT by decreasing tumoral cell growth and dissemination and could represent a new therapeutic option for children with this deadly disease.

Gliomas and meningiomas are the most common brain neoplasms affecting both humans and canines, and identifying druggable targets conserved across multiple brain cancer histologies and comparative species could broadly improve treatment outcomes. While satisfactory cure rates for low grade, non-invasive brain cancers are achievable with conventional therapies including surgery and radiation, the management of non-resectable or recurrent brain tumors remains problematic and necessitates the discovery of novel therapies that could be accelerated through a comparative approach, such as the inclusion of pet dogs with naturally-occurring brain cancers. Evidence supports procaspase-3 as a druggable brain cancer target with PAC-1, a pro-apoptotic, small molecule activator of procaspase-3 that crosses the blood-brain barrier. Procaspase-3 is frequently overexpressed in malignantly transformed tissues and provides a preferential target for inducing cancer cell apoptosis. While preliminary evidence supports procaspase-3 as a viable target in preclinical models, with PAC-1 demonstrating activity in rodent models and dogs with spontaneous brain tumors, the broader applicability of procaspase-3 as a target in human brain cancers, as well as the comparability of procaspase-3 expressions between differing species, requires further investigation. As such, a large-scale validation of procaspase-3 as a druggable target was undertaken across 651 human and canine brain tumors. Relative to normal brain tissues, procaspase-3 was overexpressed in histologically diverse cancerous brain tissues, supporting procaspase-3 as a broad and conserved therapeutic target. Additionally, procaspase-3 expressing glioma and meningioma cell lines were sensitive to the apoptotic effects of PAC-1 at biologically relevant exposures achievable in cancer patients. Importantly, the clinical relevance of procaspase-3 as a potential prognostic variable was demonstrated in human astrocytomas of variable histologic grades and associated clinical outcomes, whereby tumoral procaspase-3 expression was negatively correlated with survival; findings which suggest that PAC-1 might provide the greatest benefit for patients with the most guarded prognoses.

Over the past decade, wingless-activated (WNT) medulloblastoma has been identified as a candidate for therapy de-escalation based on excellent survival; however, a paucity of relapses has precluded additional analyses of markers of relapse. To address this gap in knowledge, an international cohort of 93 molecularly confirmed WNT MB was assembled, where 5-year progression-free survival is 0.84 (95%, 0.763-0.925) with 15 relapsed individuals identified. Maintenance chemotherapy is identified as a strong predictor of relapse, with individuals receiving high doses of cyclophosphamide or ifosphamide having only one very late molecularly confirmed relapse (p = 0.032). The anatomical location of recurrence is metastatic in 12 of 15 relapses, with 8 of 12 metastatic relapses in the lateral ventricles. Maintenance chemotherapy, specifically cumulative cyclophosphamide doses, is a significant predictor of relapse across WNT MB. Future efforts to de-escalate therapy need to carefully consider not only the radiation dose but also the chemotherapy regimen and the propensity for metastatic relapses.

To investigate the expression of angiotensin-converting enzyme 2 (ACE2), the receptor for SARS-CoV-2 in human retina.

How abnormal neurodevelopment relates to the tumour aggressiveness of medulloblastoma (MB), the most common type of embryonal tumour, remains elusive. Here we uncover a neurodevelopmental epigenomic programme that is hijacked to induce MB metastatic dissemination. Unsupervised analyses of integrated publicly available datasets with our newly generated data reveal that SMARCD3 (also known as BAF60C) regulates Disabled 1 (DAB1)-mediated Reelin signalling in Purkinje cell migration and MB metastasis by orchestrating cis-regulatory elements at the DAB1 locus. We further identify that a core set of transcription factors, enhancer of zeste homologue 2 (EZH2) and nuclear factor I X (NFIX), coordinates with the cis-regulatory elements at the SMARCD3 locus to form a chromatin hub to control SMARCD3 expression in the developing cerebellum and in metastatic MB. Increased SMARCD3 expression activates Reelin-DAB1-mediated Src kinase signalling, which results in a MB response to Src inhibition. These data deepen our understanding of how neurodevelopmental programming influences disease progression and provide a potential therapeutic option for patients with MB.

No abstract available

Treatment personalization via tumor molecular testing holds promise for improving outcomes for patients with pediatric low-grade glioma (PLGG). We evaluate the health economic impact of employing tumor molecular testing to guide treatment for patients diagnosed with PLGG, particularly the avoidance of radiation therapy (RT) for patients with BRAF-fusion.

Cancers arising from germline DNA mismatch repair deficiency or polymerase proofreading deficiency (MMRD and PPD) in children harbour the highest mutational and microsatellite insertion-deletion (MS-indel) burden in humans. MMRD and PPD cancers are commonly lethal due to the inherent resistance to chemo-irradiation. Although immune checkpoint inhibitors (ICIs) have failed to benefit children in previous studies, we hypothesized that hypermutation caused by MMRD and PPD will improve outcomes following ICI treatment in these patients. Using an international consortium registry study, we report on the ICI treatment of 45 progressive or recurrent tumors from 38 patients. Durable objective responses were observed in most patients, culminating in a 3 year survival of 41.4%. High mutation burden predicted response for ultra-hypermutant cancers (>100 mutations per Mb) enriched for combined MMRD + PPD, while MS-indels predicted response in MMRD tumors with lower mutation burden (10-100 mutations per Mb). Furthermore, both mechanisms were associated with increased immune infiltration even in 'immunologically cold' tumors such as gliomas, contributing to the favorable response. Pseudo-progression (flare) was common and was associated with immune activation in the tumor microenvironment and systemically. Furthermore, patients with flare who continued ICI treatment achieved durable responses. This study demonstrates improved survival for patients with tumors not previously known to respond to ICI treatment, including central nervous system and synchronous cancers, and identifies the dual roles of mutation burden and MS-indels in predicting sustained response to immunotherapy.

In children, higher general intelligence corresponds with better processing speed ability. However, the relationship between structural brain connectivity and processing speed in the context of intelligence is unclear. Furthermore, the impact of brain injury on this relationship is also unknown. Structural networks were constructed for 36 brain tumor patients (mean age: 13.45 ± 2.73, 58% males) and 35 typically developing children (13.30 ± 2.86, 51% males). Processing speed and general intelligence scores were acquired using standard batteries. The relationship between network properties, processing speed, and intelligence was assessed using a partial least squares analysis. Results indicated that structural networks in brain-injured children were less integrated (β = -.38, p = 0.001) and more segregated (β = 0.4, p = 0.0005) compared to typically developing children. There was an indirect effect of network segregation on general intelligence via processing speed, where greater network segregation predicted slower processing speed which in turn predicted worse general intelligence (GoF = 0.37). These findings provide the first evidence of relations between structural connectivity, processing speed, and intelligence in children. Injury-related disruption to the structural network may result in worse intelligence through impacts on information processing. Our findings are discussed in the context of a network approach to understanding brain-behavior relationships.

It has previously been reported that antioxidant vitamins can help reduce the risk of vision loss associated with progression to advanced age-related macular degeneration (AMD), a leading cause of visual impairment among the elderly. Nonetheless, how oxidative stress contributes to the development of choroidal neovascularization (CNV) in some AMD patients and geographic atrophy (GA) in others is poorly understood. Here, we provide evidence demonstrating that oxidative stress cooperates with hypoxia to synergistically stimulate the accumulation of hypoxia-inducible factor (HIF)-1α in the retinal pigment epithelium (RPE), resulting in increased expression of the HIF-1-dependent angiogenic mediators that promote CNV. HIF-1 inhibition blocked the expression of these angiogenic mediators and prevented CNV development in an animal model of ocular oxidative stress, demonstrating the pathological role of HIF-1 in response to oxidative stress stimulation in neovascular AMD. While human-induced pluripotent stem cell (hiPSC)-derived RPE monolayers exposed to chemical oxidants resulted in disorganization and disruption of their normal architecture, RPE cells proved remarkably resistant to oxidative stress. Conversely, equivalent doses of chemical oxidants resulted in apoptosis of hiPSC-derived retinal photoreceptors. Pharmacologic inhibition of HIF-1 in the mouse retina enhanced-while HIF-1 augmentation reduced-photoreceptor apoptosis in two mouse models for oxidative stress, consistent with a protective role for HIF-1 in photoreceptors in patients with advanced dry AMD. Collectively, these results suggest that in patients with AMD, increased expression of HIF-1α in RPE exposed to oxidative stress promotes the development of CNV, but inadequate HIF-1α expression in photoreceptors contributes to the development of GA.

Recent studies suggest that long non-coding RNAs (lncRNAs) contribute to medulloblastoma (MB) formation and progression. We have identified an lncRNA, lnc-HLX-2-7, as a potential therapeutic target in group 3 (G3) MBs. lnc-HLX-2-7 RNA specifically accumulates in the promoter region of HLX, a sense-overlapping gene of lnc-HLX-2-7, which activates HLX expression by recruiting multiple factors, including enhancer elements. RNA sequencing and chromatin immunoprecipitation reveal that HLX binds to and activates the promoters of several oncogenes, including TBX2, LIN9, HOXM1, and MYC. Intravenous treatment with cerium-oxide-nanoparticle-coated antisense oligonucleotides targeting lnc-HLX-2-7 (CNP-lnc-HLX-2-7) inhibits tumor growth by 40%-50% in an intracranial MB xenograft mouse model. Combining CNP-lnc-HLX-2-7 with standard-of-care cisplatin further inhibits tumor growth and significantly prolongs mouse survival compared with CNP-lnc-HLX-2-7 monotherapy. Thus, the lnc-HLX-2-7-HLX-MYC axis is important for regulating G3 MB progression, providing a strong rationale for using lnc-HLX-2-7 as a therapeutic target for G3 MBs.

Retinoblastoma is the most common intraocular malignancy in children. We previously found that the ACVR1C/SMAD2 pathway is significantly upregulated in invasive retinoblastoma samples from patients. Here we studied the role of an ACVR1C ligand, Nodal, in regulating growth and metastatic dissemination in retinoblastoma. Inhibition of Nodal using multiple short hairpin (shRNAs) in WERI Rb1 and Y79 retinoblastoma cell cultures reduced growth by more than 90%, as determined by CCK-8 growth assay. Proliferation was also significantly inhibited, as found by Ki67 assay. These effects were paralleled by inhibition in the phosphorylation of the downstream effector SMAD2, as well as induction of apoptosis, as we observed more than three-fold increase in the percentage of cells positive for cleaved-caspase-3 or expressing cleaved-PARP1. Importantly, we found that downregulation of Nodal potently suppressed invasion in vitro, by 50 to 80%, as determined by transwell invasion assay (p = 0.02). Using an orthotopic model of retinoblastoma in zebrafish, we found 34% reduction in the ability of the cells to disseminate outside the eye, when Nodal was knocked down by shRNA (p = 0.0003). These data suggest that Nodal plays an important role in promoting growth, proliferation and invasion in retinoblastoma, and can be considered a new therapeutic target for both primary tumor growth and metastatic progression.

Facial emotion recognition (FER) deficits are evident and pervasive across neurodevelopmental, psychiatric, and acquired brain disorders in children, including children treated for brain tumours. Such deficits are thought to perpetuate challenges with social relationships and decrease quality of life. The present study combined eye-tracking, neuroimaging and cognitive assessments to evaluate if visual attention, brain structure, and general cognitive function contribute to FER in children treated for posterior fossa (PF) tumours (patients: n = 36) and typically developing children (controls: n = 18). To assess FER, all participants completed the Diagnostic Analysis of Nonverbal Accuracy (DANVA2), a computerized task that measures FER using photographs, while their eye-movements were recorded. Patients made more FER errors than controls (p < .01). Although we detected subtle deficits in visual attention and general cognitive function in patients, we found no associations with FER. Compared to controls, patients had evidence of white matter (WM) damage, (i.e., lower fractional anisotropy [FA] and higher radial diffusivity [RD]), in multiple regions throughout the brain (all p < .05), but not in specific WM tracts associated with FER. Despite the distributed WM differences between groups, WM predicted FER in controls only. In patients, factors associated with their disease and treatment predicted FER. Our study provides insight into predictors of FER that may be unique to children treated for PF tumours, and highlights a divergence in associations between brain structure and behavioural outcomes in clinical and typically developing populations; a concept that may be broadly applicable to other neurodevelopmental and clinical populations that experience FER deficits.

Activation of the RAS-RAF-MEK-ERK signaling pathway is thought to be the key driver of pediatric low-grade astrocytoma (PLGA) growth. Sorafenib is a multikinase inhibitor targeting BRAF, VEGFR, PDGFR, and c-kit. This multicenter phase II study was conducted to determine the response rate to sorafenib in patients with recurrent or progressive PLGA.

Glioblastoma multiforme (GBM) is the most aggressive and lethal type of brain tumor. Standard treatment for GBM patients is surgery followed by radiotherapy and/or chemotherapy, but tumors always recur. Traditional therapies seem to fail because they eliminate only the bulk of the tumors and spare a population of stem-like cells termed tumor-initiating cells. The stem-like state and preferential activation of DNA damage response in the GBM tumor-initiating cells contribute to their radio-resistance and recurrence. The molecular mechanisms underlying this efficient activation of damage response and maintenance of stem-like state remain elusive. Here we show that RBM14 controls DNA repair pathways and also prevents cell differentiation in GBM spheres, causing radio-resistance. Knockdown of RBM14 affects GBM sphere maintenance and sensitizes radio-resistant GBM cells at the cellular level. We demonstrate that RBM14 knockdown blocks GBM regrowth after irradiation in vivo. In addition, RBM14 stimulates DNA repair by controlling the DNA-PK-dependent non-homologous end-joining (NHEJ) pathway. These results reveal unexpected functions of the RNA-binding protein RBM14 in control of DNA repair and maintenance of tumor-initiating cells. Targeting the RBM14-dependent pathway may prevent recurrence of tumors and eradicate the deadly disease completely.

Cancers must maintain their telomeres at lengths sufficient for cell survival. In several cancer subtypes, a recombination-like mechanism termed alternative lengthening of telomeres (ALT), is frequently used for telomere length maintenance. Cancers utilizing ALT often have lost functional ATRX, a chromatin remodeling protein, through mutation or deletion, thereby strongly implicating ATRX as an ALT suppressor. Herein, we have generated functional ATRX knockouts in four telomerase-positive, ALT-negative human glioma cell lines: MOG-G-UVW, SF188, U-251 and UW479. After loss of ATRX, two of the four cell lines (U-251 and UW479) show multiple characteristics of ALT-positive cells, including ultrabright telomeric DNA foci, ALT-associated PML bodies, and c-circles. However, telomerase activity and overall telomere length heterogeneity are unaffected after ATRX loss, regardless of cellular context. The two cell lines that showed ALT hallmarks after complete ATRX loss also did so upon ATRX depletion via shRNA-mediated knockdown. These results suggest that other genomic or epigenetic events, in addition to ATRX loss, are necessary for the induction of ALT in human cancer.

Glioblastoma multiforme (GBM) are the most common primary malignant brain tumor in adults, with a median survival of about one year. This poor prognosis is attributed primarily to therapeutic resistance and tumor recurrence after surgical removal, with the root cause suggested to be found in glioblastoma stem cells (GSCs). Using glial fibrillary acidic protein (GFAP) as a reporter of astrocytic differentiation, we isolated multiple clones from three independent GSC lines which express GFAP in a remarkably stable fashion. We next show that elevated expression of GFAP is associated with reduced clonogenicity in vitro and tumorigenicity in vivo. Utilizing this in vitro cell-based differentiation reporter system we screened chemical libraries and identified the non-depolarizing neuromuscular blocker (NNMB), Atracurium Besylate, as a small molecule which effectively induces astroglial but not neuronal differentiation of GSCs. Functionally, Atracurium Besylate treatment significantly inhibited the clonogenic capacity of several independent patient-derived GSC neurosphere lines, a phenomenon which was largely irreversible. A second NNMB, Vecuronium, also induced GSC astrocytic differentiation while Dimethylphenylpiperazinium (DMPP), a nicotinic acetylcholine receptor (nAChR) agonist, significantly blocked Atracurium Besylate pro-differentiation activity. To investigate the clinical importance of nAChRs in gliomas, we examined clinical outcomes and found that glioma patients with tumors overexpressing CHRNA1 or CHRNA9 (encoding for the AChR-α1 or AChR-α9) exhibit significant shorter overall survival. Finally, we found that ex-vivo pre-treatment of GSCs, expressing CHRNA1 and CHRNA9, with Atracurium Besylate significantly increased the survival of mice xenotransplanted with these cells, therefore suggesting that tumor initiating subpopulations have been reduced.

Atypical teratoid rhabdoid tumor (AT/RT) is among the most fatal of all pediatric brain tumors. Aside from loss of function mutations in the SMARCB1 (BAF47/INI1/SNF5) chromatin remodeling gene, little is known of other molecular drivers of AT/RT. LIN28A and LIN28B are stem cell factors that regulate thousands of RNAs and are expressed in aggressive cancers. We identified high-levels of LIN28A and LIN28B in AT/RT primary tumors and cell lines, with corresponding low levels of the LIN28-regulated microRNAs of the let-7 family. Knockdown of LIN28A by lentiviral shRNA in the AT/RT cell lines CHLA-06-ATRT and BT37 inhibited growth, cell proliferation and colony formation and induced apoptosis. Suppression of LIN28A in orthotopic xenograft models led to a more than doubling of median survival compared to empty vector controls (48 vs 115 days). LIN28A knockdown led to increased expression of let-7b and let-7g microRNAs and a down-regulation of KRAS mRNA. AT/RT primary tumors expressed increased mitogen activated protein (MAP) kinase pathway activity, and the MEK inhibitor selumetinib (AZD6244) decreased AT/RT growth and increased apoptosis. These data implicate LIN28/RAS/MAP kinase as key drivers of AT/RT tumorigenesis and indicate that targeting this pathway may be a therapeutic option in this aggressive pediatric malignancy.

The cellular reprogramming factor LIN28A promotes tumorigenicity in cancers arising outside the central nervous system, but its role in brain tumors is unknown. We detected LIN28A protein in a subset of human gliomas observed higher expression in glioblastoma (GBM) than in lower grade tumors. Knockdown of LIN28A using lentiviral shRNA in GBM cell lines inhibited their invasion, growth and clonogenicity. Expression of LIN28A in GBM cell lines increased the number and size of orthotopic xenograft tumors. LIN28A expression also enhanced the invasiveness of GBM cells in vitro and in vivo. Increasing LIN28A was associated with down-regulation of tumor suppressing microRNAs let-7b and let-7g and up-regulation of the chromatin modifying protein HMGA2. The increase in tumor cell aggressiveness in vivo and in vitro was accompanied by an upregulation of pro-invasive gene expression, including SNAI1. To further investigate the oncogenic potential of LIN28A, we infected hNSC with lentiviruses encoding LIN28A together with dominant negative R248W-TP53, constitutively active KRAS and hTERT. Resulting subclones proliferated at an increased rate and formed invasive GBM-like tumors in orthotopic xenografts in immunodeficient mice. Similar to LIN28A-transduced GBM neurosphere lines, hNSC-derived tumor cells showed increased expression of HMGA2. Taken together, these data suggest a role for LIN28A in high grade gliomas and illustrate an HMGA2-associated, pro-invasive program that can be activated in GBM by LIN28A-mediated suppression of let-7 microRNAs.

Convection enhanced delivery (CED) provides a powerful means to bypass the blood-brain barrier and drive widespread distribution of therapeutics in brain parenchyma away from the point of local administration. However, recent studies have detailed that the overall distribution of therapeutic nanoparticles (NP) following CED remains poor due to tissue inhomogeneity and anatomical barriers present in the brain, which has limited its translational applicability. Using probe NP, we first demonstrate that a significantly improved brain distribution is achieved by infusing small, non-adhesive NP via CED in a hyperosmolar infusate solution. This multimodal delivery strategy minimizes the hindrance of NP diffusion imposed by the brain extracellular matrix and reduces NP confinement within the perivascular spaces. We further recapitulate the distributions achieved by CED of this probe NP using a most widely explored biodegradable polymer-based drug delivery NP. These findings provide a strategy to overcome several key limitations of CED that have been previously observed in clinical trials.