Overexpression of miR-340 inhibits cell proliferation and induces apoptosis of human bladder cancer via targeting Glut-1.

BACKGROUND: Bladder cancer (BC) has high mortality due to distant metastasis. Previous works suggested that microRNA (miRNA)-340 is a critical regulator for the development and progression of various cancers. The specific biological function of miR-340 in BC is little known. METHODS: In the present study, RT-qPCR was performed to measure the expression of miR-340 in paired BC tissues and adjacent non-tumor tissues. Next, the target gene of miR-340 was identified using dual-luciferase reporter assay and its level was also tested in tissues. Moreover, cell proliferation and apoptosis were analyzed by CCK-8 and flow cytometry. Finally, the expression of PCNA, Bax was detected by RT-qPCR and western blotting, as well as PI3K/AKT signaling measured by western blotting. RESULT: The results demonstrated that miR-340 expression was downregulated and its target Glut-1 level was upregulated in BC tissues. Functionally, overexpression of miR-340 suppressed the proliferation and induced apoptosis in BC cells, while Glut-1 reversed the suppression of proliferation or induction of apoptosis induced by miR-340. Additionally, miR-340 repressed PCNA, p-PI3K and p-AKT levels but enhanced Bax level, while Glut-1 rescued the effects. CONCLUSION: In conclusion, miR-340 functions as a tumor suppressor of BC, which inhibited proliferation and induced apoptosis by targeting Glut-1 partly through regulating PCNA, Bax expression and PI3K/AKT pathway. This study suggested that miR-340 is a potential target for the treatment of BC.

GLUT1 overexpression enhances glucose metabolism and promotes neonatal heart regeneration.

The mammalian heart switches its main metabolic substrate from glucose to fatty acids shortly after birth. This metabolic switch coincides with the loss of regenerative capacity in the heart. However, it is unknown whether glucose metabolism regulates heart regeneration. Here, we report that glucose metabolism is a determinant of regenerative capacity in the neonatal mammalian heart. Cardiac-specific overexpression of Glut1, the embryonic form of constitutively active glucose transporter, resulted in an increase in glucose uptake and concomitant accumulation of glycogen storage in postnatal heart. Upon cryoinjury, Glut1 transgenic hearts showed higher regenerative capacity with less fibrosis than non-transgenic control hearts. Interestingly, flow cytometry analysis revealed two distinct populations of ventricular cardiomyocytes: Tnnt2-high and Tnnt2-low cardiomyocytes, the latter of which showed significantly higher mitotic activity in response to high intracellular glucose in Glut1 transgenic hearts. Metabolic profiling shows that Glut1-transgenic hearts have a significant increase in the glucose metabolites including nucleotides upon injury. Inhibition of the nucleotide biosynthesis abrogated the regenerative advantage of high intra-cardiomyocyte glucose level, suggesting that the glucose enhances the cardiomyocyte regeneration through the supply of nucleotides. Our data suggest that the increase in glucose metabolism promotes cardiac regeneration in neonatal mouse heart.

Glutamate transporter-1 link astrocytes with heightened aggressive behavior induced by steroid abuse in male CF1 mice.

The astrocytic glutamate transporter GLT-1 performs glutamate uptake thereby mediating NMDAr responses in neurons. Ceftriaxone (CEF) upregulates astrocytic GLT-1 expression/activity, which could counteract excessive glutamate levels and aggressive behavior induced by anabolic synthetic steroids such as nandrolone decanoate (ND). Here, adult male CF-1 mice were allocated to oil (VEH), ND, CEF, and ND/CEF groups. Mice were subcutaneously (s.c.) injected with ND (15 mg/kg) or VEH for 19 days, and received intraperitoneal (i.p.) injections of CEF (200 mg/kg) or saline for 5 days. The ND/CEF group received ND for 19 days plus coadministration of CEF in the last 5 days. On the 19th day, the aggressive phenotypes were evaluated through the resident-intruder test. After 24 h, cerebrospinal fluid was collected to measure glutamate levels, and the pre-frontal cortex was used to assess GLT-1, pGluN2BTyr1472, and pGluN2ATyr1246 by Western blot. Synaptosomes from the left brain hemisphere was used to evaluate mitochondrial function including complex II-succinate dehydrogenase (SDH), Ca2+ handling, membrane potential (ΔÑ°m), and H2O2 production. ND decreased the latency for the first attack and increased the number of attacks by the resident mice against the intruder, mechanistically associated with an increase in glutamate levels and pGluN2BTyr1472 but not pGluN2ATyr1244, and GLT-1 downregulation. The abnormalities in mitochondrial Ca2+ influx, SDH, ΔÑ°m, and H2O2 implies in deficient energy support to the synaptic machinery. The ND/CEF group displayed a decreased aggressive behavior, normalization of glutamate and pGluN2BTyr1472levels, and mitochondrial function at synaptic terminals. In conclusion, the pharmacological modulation of GLT-1 highlights its relevance as an astrocytic target against highly impulsive and aggressive phenotypes.

Role of the GLUT1 Glucose Transporter in Postnatal CNS Angiogenesis and Blood-Brain Barrier Integrity.

RATIONALE: Endothelial cells (ECs) are highly glycolytic and generate the majority of their energy via the breakdown of glucose to lactate. At the same time, a main role of ECs is to allow the transport of glucose to the surrounding tissues. GLUT1 (glucose transporter isoform 1/Slc2a1) is highly expressed in ECs of the central nervous system (CNS) and is often implicated in blood-brain barrier (BBB) dysfunction, but whether and how GLUT1 controls EC metabolism and function is poorly understood. OBJECTIVE: We evaluated the role of GLUT1 in endothelial metabolism and function during postnatal CNS development as well as at the adult BBB. METHODS AND RESULTS: Inhibition of GLUT1 decreases EC glucose uptake and glycolysis, leading to energy depletion and the activation of the cellular energy sensor AMPK (AMP-activated protein kinase), and decreases EC proliferation without affecting migration. Deletion of GLUT1 from the developing postnatal retinal endothelium reduces retinal EC proliferation and lowers vascular outgrowth, without affecting the number of tip cells. In contrast, in the brain, we observed a lower number of tip cells in addition to reduced brain EC proliferation, indicating that within the CNS, organotypic differences in EC metabolism exist. Interestingly, when ECs become quiescent, endothelial glycolysis is repressed, and GLUT1 expression increases in a Notch-dependent fashion. GLUT1 deletion from quiescent adult ECs leads to severe seizures, accompanied by neuronal loss and CNS inflammation. Strikingly, this does not coincide with BBB leakiness, altered expression of genes crucial for BBB barrier functioning nor reduced vascular function. Instead, we found a selective activation of inflammatory and extracellular matrix related gene sets. CONCLUSIONS: GLUT1 is the main glucose transporter in ECs and becomes uncoupled from glycolysis during quiescence in a Notch-dependent manner. It is crucial for developmental CNS angiogenesis and adult CNS homeostasis but does not affect BBB barrier function.

Localisation and function of glucose transporter GLUT1 in chicken (Gallus gallus domesticus) spermatozoa: relationship between ATP production pathways and flagellar motility.

Glucose plays an important role in sperm flagellar motility and fertility via glycolysis and oxidative phosphorylation, although the primary mechanisms for ATP generation vary between species. The glucose transporter 1 (GLUT1) is a high-affinity isoform and a major glucose transporter in mammalian spermatozoa. However, in avian spermatozoa, the glucose metabolic pathways are poorly characterised. This study demonstrates that GLUT1 plays a major role in glucose-mediated motility of chicken spermatozoa. Using specific antibodies and ligand, we found that GLUT1 was specifically localised to the midpiece. Sperm motility analysis showed that glucose supported sperm movement during incubation for 0-80min. However, this was abolished by the addition of a GLUT1 inhibitor, concomitant with a substantial decrease in glucose uptake and ATP production, followed by elevated mitochondrial activity in response to glucose addition. More potent inhibition of ATP production and mitochondrial activity was observed in response to treatment with uncouplers of oxidative phosphorylation. Because mitochondrial inhibition only reduced a subset of sperm movements, we investigated the localisation of the glycolytic pathway and showed glyceraldehyde-3-phosphate dehydrogenase and hexokinase I at the midpiece and principal piece of the flagellum. The results of this study provide new insights into the mechanisms involved in ATP production pathways in avian spermatozoa.

Glycoconjugation as a Promising Treatment Strategy for Psoriasis.

Despite the progress in the development of novel treatment modalities, a significant portion of patients with psoriasis remains undertreated relative to the severity of their disease. Recent evidence points to targeting the glucose transporter 1 and sugar metabolism as a novel therapeutic strategy for the treatment of psoriasis and other hyperproliferative skin diseases. In this review, we discuss glycoconjugation, an approach that facilitates the pharmacokinetics of cytotoxic molecules and ensures their preferential influx through glucose transporters. We propose pathways of glycoconjugate synthesis to increase effectiveness, cellular selectivity, and tolerability of widely used antipsoriatic drugs. The presented approach exploiting the heightened glucose requirement of proliferating keratinocytes bears the potential to revolutionize the management of psoriasis. SIGNIFICANCE STATEMENT: Recent findings concerning the fundamental role of enhanced glucose metabolism and glucose transporter 1 overexpression in the pathogenesis of psoriasis brought to light approaches that proved successful in cancer treatment. Substantial advances in the emerging field of glycoconjugation highlight the rationale for the development of glucose-conjugated antipsoriatic drugs to increase their effectiveness, cellular selectivity, and tolerability. The presented approach offers a novel therapeutic strategy for the treatment of psoriasis and other hyperproliferative skin diseases.

Does 2-FDG PET Accurately Reflect Quantitative In Vivo Glucose Utilization?

2-Deoxy-2-18F-fluoro-d-glucose (2-FDG) with PET is undeniably useful in the clinic, being able, among other uses, to monitor change over time using the 2-FDG SUV metric. This report suggests some potentially serious caveats for this and related roles for 2-FDG PET. Most critical is the assumption that there is an exact proportionality between glucose metabolism and 2-FDG metabolism, called the lumped constant, or LC. This report describes that LC is not constant for a specific tissue and may be variable before and after disease treatment. The purpose of this work is not to deny the clinical value of 2-FDG PET; it is a reminder that when one extends the use of an appropriately qualified imaging method, new observations may arise and further validation would be necessary. The current understanding of glucose-based energetics in vivo is based on the quantification of glucose metabolic rates with 2-FDG PET, a method that permits the noninvasive assessment of various human disorders. However, 2-FDG is a good substrate only for facilitated-glucose transporters (GLUTs), not for sodium-dependent glucose cotransporters (SGLTs), which have recently been shown to be distributed in multiple human tissues. Thus, the GLUT-mediated in vivo glucose utilization measured by 2-FDG PET would be masked to the potentially substantial role of functional SGLTs in glucose transport and use. Therefore, under these circumstances, the 2-FDG LC used to quantify in vivo glucose utilization should not be expected to remain constant. 2-FDG LC variations have been especially significant in tumors, particularly at different stages of cancer development, affecting the accuracy of quantitative glucose measures and potentially limiting the prognostic value of 2-FDG, as well as its accuracy in monitoring treatments. SGLT-mediated glucose transport can be estimated using α-methyl-4-deoxy-4-18F-fluoro-d-glucopyranoside (Me-4FDG). Using both 2-FDG and Me-4FDG should provide a more complete picture of glucose utilization via both GLUT and SGLT transporters in health and disease states. Given the widespread use of 2-FDG PET to infer glucose metabolism, it is relevant to appreciate the potential limitations of 2-FDG as a surrogate for glucose metabolic rate and the potential reasons for variability in LC. Even when the readout for the 2-FDG PET study is only an SUV parameter, variability in LC is important, particularly if it changes over the course of disease progression (e.g., an evolving tumor).

p63 and SOX2 Dictate Glucose Reliance and Metabolic Vulnerabilities in Squamous Cell Carcinomas.

Squamous cell carcinoma (SCC), a malignancy arising across multiple anatomical sites, is responsible for significant cancer mortality due to insufficient therapeutic options. Here, we identify exceptional glucose reliance among SCCs dictated by hyperactive GLUT1-mediated glucose influx. Mechanistically, squamous lineage transcription factors p63 and SOX2 transactivate the intronic enhancer cluster of SLC2A1. Elevated glucose influx fuels generation of NADPH and GSH, thereby heightening the anti-oxidative capacity in SCC tumors. Systemic glucose restriction by ketogenic diet and inhibiting renal glucose reabsorption with SGLT2 inhibitor precipitate intratumoral oxidative stress and tumor growth inhibition. Furthermore, reduction of blood glucose lowers blood insulin levels, which suppresses PI3K/AKT signaling in SCC cells. Clinically, we demonstrate a robust correlation between blood glucose concentration and worse survival among SCC patients. Collectively, this study identifies the exceptional glucose reliance of SCC and suggests its candidacy as a highly vulnerable cancer type to be targeted by systemic glucose restriction.

Bioluminescent-based imaging and quantification of glucose uptake in vivo.

Glucose is a major source of energy for most living organisms, and its aberrant uptake is linked to many pathological conditions. However, our understanding of disease-associated glucose flux is limited owing to the lack of robust tools. To date, positron-emission tomography imaging remains the gold standard for measuring glucose uptake, and no optical tools exist for non-invasive longitudinal imaging of this important metabolite in in vivo settings. Here, we report the development of a bioluminescent glucose-uptake probe for real-time, non-invasive longitudinal imaging of glucose absorption both in vitro and in vivo. In addition, we demonstrate that the sensitivity of our method is comparable with that of commonly used 18F-FDG-positron-emission-tomography tracers and validate the bioluminescent glucose-uptake probe as a tool for the identification of new glucose transport inhibitors. The new imaging reagent enables a wide range of applications in the fields of metabolism and drug development.

Increased glycolysis mediates Wnt7b-induced bone formation.

Wingless/integrated (Wnt) signaling has emerged as a major mechanism for promoting bone formation and a target pathway for developing bone anabolic agents against osteoporosis. However, the downstream events mediating the potential therapeutic effect of Wnt proteins are not fully understood. Previous studies have indicated that increased glycolysis is associated with osteoblast differentiation in response to Wnt signaling, but direct genetic evidence for the importance of glucose metabolism in Wnt-induced bone formation is lacking. Here, we have generated compound transgenic mice to overexpress Wnt family member 7B (Wnt7b) transiently in the osteoblast lineage of postnatal mice, with or without concurrent deletion of the glucose transporter 1 (Glut1), also known as solute carrier family 2, facilitated glucose transporter member 1. Overexpression of Wnt7b in 1-mo-old mice for 1 wk markedly stimulated bone formation, but the effect was essentially abolished without Glut1, even though transient deletion of Glut1 itself did not affect normal bone accrual. Consistent with the in vivo results, Wnt7b increased Glut1 expression and glucose consumption in the primary culture of osteoblast lineage cells, and deletion of Glut1 diminished osteoblast differentiation in vitro. Thus, Wnt7b promotes bone formation in part through stimulating glucose metabolism in osteoblast lineage cells.-Chen, H., Ji, X., Lee, W.-C., Shi, Y., Li, B., Abel, E. D., Jiang, D., Huang, W., Long, F. Increased glycolysis mediates Wnt7b-induced bone formation.

HTLV-1 Tax-1 interacts with SNX27 to regulate cellular localization of the HTLV-1 receptor molecule, GLUT1.

An estimated 10-20 million people worldwide are infected with human T cell leukemia virus type 1 (HTLV-1), with endemic areas of infection in Japan, Australia, the Caribbean, and Africa. HTLV-1 is the causative agent of adult T cell leukemia (ATL) and HTLV-1 associated myopathy/tropic spastic paraparesis (HAM/TSP). HTLV-1 expresses several regulatory and accessory genes that function at different stages of the virus life cycle. The regulatory gene Tax-1 is required for efficient virus replication, as it drives transcription of viral gene products, and has also been demonstrated to play a key role in the pathogenesis of the virus. Several studies have identified a PDZ binding motif (PBM) at the carboxyl terminus of Tax-1 and demonstrated the importance of this domain for HTLV-1 induced cellular transformation. Using a mass spectrometry-based proteomics approach we identified sorting nexin 27 (SNX27) as a novel interacting partner of Tax-1. Further, we demonstrated that their interaction is mediated by the Tax-1 PBM and SNX27 PDZ domains. SNX27 has been shown to promote the plasma membrane localization of glucose transport 1 (GLUT1), one of the receptor molecules of the HTLV-1 virus, and the receptor molecule required for HTLV-1 fusion and entry. We postulated that Tax-1 alters GLUT1 localization via its interaction with SNX27. We demonstrate that over expression of Tax-1 in cells causes a reduction of GLUT1 on the plasma membrane. Furthermore, we show that knockdown of SNX27 results in increased virion release and decreased HTLV-1 infectivity. Collectively, we demonstrate the first known mechanism by which HTLV-1 regulates a receptor molecule post-infection.

Regional differences in mitral cell development in mouse olfactory bulb.

Olfactory sensory neurons (OSNs) located in the dorsomedial and ventromedial regions of the olfactory epithelium (OE) are distinguished from one another based on their molecular expression patterns. This difference is reflected in the separation of the glomerular layer of the olfactory bulb (OB) into dorsomedial and ventrolateral regions. However, it is unclear whether a complementary separation is also evident in the projection neurons that innervate the OB glomeruli. In this study, we compared the development of the OB between different regions by focusing on the transcription factor, Tbx21, which is expressed by mitral and tufted cells in the mature OB. Examining the OB at different developmental ages, we found that Tbx21 expression commenced in the anteromedial region called the tongue-shaped area, followed by the dorsomedial and then ventrolateral areas. We also showed that the tongue-shaped area was innervated by the OSNs located in the most dorsomedial part of the ventrolateral OE, the V-zone:DM. Interestingly, the generation of OSNs occurred first in the dorsomedial zone including the V-zone:DM, suggesting a correlation between the time course of OSN generation in the OE and Tbx21 expression in their target region of the OB. In contrast, expression of vGluT1, which is also found in all mitral cells in the mature OB, was first detected in the ventrolateral region during development. Our findings demonstrate that the development of projection neurons occurs in a compartmentalized manner in the OB; tongue-shaped, dorsomedial, and ventrolateral areas, and that not all projection neurons follow the same developmental pathway.

Mutations in Disordered Regions Can Cause Disease by Creating Dileucine Motifs.

Many disease-causing missense mutations affect intrinsically disordered regions (IDRs) of proteins, but the molecular mechanism of their pathogenicity is enigmatic. Here, we employ a peptide-based proteomic screen to investigate the impact of mutations in IDRs on protein-protein interactions. We find that mutations in disordered cytosolic regions of three transmembrane proteins (GLUT1, ITPR1, and CACNA1H) lead to an increased clathrin binding. All three mutations create dileucine motifs known to mediate clathrin-dependent trafficking. Follow-up experiments on GLUT1 (SLC2A1), the glucose transporter causative of GLUT1 deficiency syndrome, revealed that the mutated protein mislocalizes to intracellular compartments. Mutant GLUT1 interacts with adaptor proteins (APs) in vitro, and knocking down AP-2 reverts the cellular mislocalization and restores glucose transport. A systematic analysis of other known disease-causing variants revealed a significant and specific overrepresentation of gained dileucine motifs in structurally disordered cytosolic domains of transmembrane proteins. Thus, several mutations in disordered regions appear to cause "dileucineopathies."

miR-328 mediates a metabolic shift in colon cancer cells by targeting SLC2A1/GLUT1.

PURPOSE: Increasing evidence shows that altered metabolism is a critical hallmark in colon cancer. There is a strong need to explore the molecular mechanisms underlying cancer metabolism. Whether the aberrant expression of microRNAs contributes to cancer metabolism is not fully understood. miR-328 is a putative potential target of SLC2A1, but the regulating mechanism between them remains unknown. We have examined whether miR-328 directly regulates SLC2A1/GLUT1 expression in colon cancer cells. METHODS: We performed in silico bioinformatic analyses to identify miR-328-mediated molecular pathways and targets. We also performed luciferase assays and western blot analyses in LOVO and SW480 colon cancer cell lines. In addition, we assessed miR-328 expression in 47 paired tumor and normal tissue specimens from resected colon cancer patients. RESULTS: Luciferase reporter assays showed that miR-328 directly targeted SLC2A1 3'-untranslated region (UTR), with a significant decrease in luciferase activity in both LOVO and SW480 cell lines. These results were validated by western blot. miR-328 expression was significantly downregulated in tumor tissue compared with paired normal tissue. CONCLUSIONS: Our results show that miR-328 targets SLC2A1/GLUT1. We suggest that miR-328 may be involved in the orchestration of the Warburg effect in colon cancer cells. Furthermore, miR-328 expression is reduced in colon cancer patients and thus inversely correlates with the classically reported upregulated SLC2A1/GLUT1 expression in tumors.

MicroRNAs and altered metabolism of clear cell renal cell carcinoma: Potential role as aerobic glycolysis biomarkers.

BACKGROUND: Warburg Effect is a metabolic switch that occurs in most of cancer cells but its advantages are not fully understood. This switch is known to happen in renal cell carcinoma (RCC), which is the most common solid cancer of the adult kidney. RCC carcinogenesis is related to pVHL loss and Hypoxia Inducible Factor (HIF) activation, ultimately leading to the activation of several genes related to glycolysis. MicroRNAs (miRNAs) regulate gene expression at a post-transcriptional level and are also deregulated in several cancers, including RCC. SCOPE OF REVIEW: This review focuses in the miRNAs that direct target enzymes involved in glycolysis and that are deregulated in several cancers. It also reviews the possible application of miRNAs in the improvement of clinical patients' management. MAJOR CONCLUSIONS: Several miRNAs that direct target enzymes involved in glycolysis are downregulated in cancer, strongly influencing the Warburg Effect. Due to this strong influence, FDG-PET can possibly benefit from measurement of these miRNAs. Restoring their levels can also bring an improvement to the current therapies. GENERAL SIGNIFICANCE: Despite being known for almost a hundred years, the Warburg Effect is not fully understood. MiRNAs are now known to be intrinsically connected with this effect and present an opportunity to understand it. They also open a new door to improve current diagnosis and prognosis tests as well as to complement current therapies. This is urgent for cancers like RCC, mostly due to the lack of an efficient screening test for early relapse detection and follow-up and the development of resistance to current therapies.

Glut1 promotes cell proliferation, migration and invasion by regulating epidermal growth factor receptor and integrin signaling in triple-negative breast cancer cells.

Elevated glucose levels in cancer cells can be attributed to increased levels of glucose transporter (GLUT) proteins. Glut1 expression is increased in human malignant cells. To investigate alternative roles of Glut1 in breast cancer, we silenced Glut1 in triple-negative breast-cancer cell lines using a short hairpin RNA (shRNA) system. Glut1 silencing was verified by Western blotting and qRT-PCR. Knockdown of Glut1 resulted in decreased cell proliferation, glucose uptake, migration, and invasion through modulation of the EGFR/ MAPK signaling pathway and integrin ß1/Src/FAK signaling pathways. These results suggest that Glut1 not only plays a role as a glucose transporter, but also acts as a regulator of signaling cascades in the tumorigenesis of breast cancer. [BMB Reports 2017; 50(3): 132-137].

Repurposing the anti-malarial drug dihydroartemisinin suppresses metastasis of non-small-cell lung cancer via inhibiting NF-κB/GLUT1 axis.

Non-small-cell lung cancer (NSCLC) is an aggressive malignancy and long-term survival remains unsatisfactory for patients with metastatic and recurrent disease. Repurposing the anti-malarial drug dihydroartemisinin (DHA) has been proved to possess potent antitumor effect on various cancers. However, the effects of DHA in preventing the invasion of NSCLC cells have not been studied. In the present study, we determined the inhibitory effects of DHA on invasion and migration and the possible mechanisms involved using A549 and H1975 cells. DHA inhibited in vitro migration and invasion of NSCLC cells even in low concentration with little cytotoxicity. Additionally, low concentration DHA also inhibited Warburg effect in NSCLC cells. Mechanically, DHA negatively regulates NF-κB signaling to inhibit the GLUT1 translocation. Blocking the NF-κB signaling largely abolishes the inhibitory effects of DHA on the translocation of GLUT1 to the plasma membrane and the Warburg effect. Furthermore, GLUT1 knockdown significantly decreased the inhibition of invasion, and migration by DHA. Our results suggested that DHA can inhibit metastasis of NSCLC by targeting glucose metabolism via inhibiting NF-κB signaling pathway and DHA may deserve further investigation in NSCLC treatment.

Medulloblastoma Genotype Dictates Blood Brain Barrier Phenotype.

The childhood brain tumor, medulloblastoma, includes four subtypes with very different prognoses. Here, we show that paracrine signals driven by mutant ß-catenin in WNT-medulloblastoma, an essentially curable form of the disease, induce an aberrant fenestrated vasculature that permits the accumulation of high levels of intra-tumoral chemotherapy and a robust therapeutic response. In contrast, SHH-medulloblastoma, a less curable disease subtype, contains an intact blood brain barrier, rendering this tumor impermeable and resistant to chemotherapy. The medulloblastoma-endothelial cell paracrine axis can be manipulated in vivo, altering chemotherapy permeability and clinical response. Thus, medulloblastoma genotype dictates tumor vessel phenotype, explaining in part the disparate prognoses among medulloblastoma subtypes and suggesting an approach to enhance the chemoresponsiveness of other brain tumors.