Impaired Anaplerosis Is a Major Contributor to Glycolysis Inhibitor Toxicity in Glioma

Abstract Reprogramming of metabolic pathways is crucial to satisfy the bioenergetic and biosynthetic demands and maintain the redox status of rapidly proliferating cancer cells. In tumors, the tricarboxylic acid (TCA) cycle generates biosynthetic intermediates by oxidation of anaplerotic substrates, such as glucose-derived pyruvate and glutamine20 derived glutamate. We have previously documented that a subset of tumors with 1p36 homozygous deletion exhibit co-deletion of ENO1, in turn becoming extremely dependent on its redundant isoform ENO2 and sensitive to an overall enzymatic deficiency of enolase. Metabolomic profiling of ENO1-deleted glioma cells treated with an enolase inhibitor revealed a profound decrease in TCA cycle metabolites, which correlated with cell-line specific sensitivity to enolase inhibition, highlighting the importance of glycolysis derived pyruvate for anaplerosis. Correspondingly, the toxicity of the enolase inhibitor was significantly attenuated by exogenous supplementation of supraphysiological levels of anaplerotic substrates including pyruvate. These findings led us to hypothesize that cancer cells with ENO1 homozygous deletions treated with an enolase inhibitor might show exceptional sensitivity to inhibition of glutaminolysis because of reduced anaplerotic flow from glycolysis. We found that ENO1-deleted cells indeed exhibited selective sensitivity to the glutaminase inhibitor CB-839, and this sensitivity was also attenuated by exogenous supplementation of anaplerotic substrates including pyruvate. Despite these promising in vitro results, the antineoplastic effects of CB-839 as a single agent in ENO1-deleted xenograft tumors in vivo were modest in both intracranial orthotopic tumors, where the limited efficacy could be attributed to the blood brain barrier (BBB), and subcutaneous xenografts, where BBB penetration is not an issue. This contrasts with the enolase inhibitor HEX, which, despite its negative charge, achieved antineoplastic effects in both intracranial and subcutaneous tumors. Together, these data suggest that at least for 1p36-deleted gliomas, tumors in vivo—unlike cells in culture—show limited dependence on glutaminolysis and instead primarily depend on glycolysis for anaplerosis. Our findings reinforce the previously reported metabolic idiosyncrasies of the in vitro and in vivo environments as the potential reasons for the differential efficacy of metabolism targeted therapies in in vitro and in vivo systems.

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Impaired anaplerosis is a major contributor to glycolysis inhibitor toxicity in glioma

Cancer & Metabolism ◽

10.1186/s40170-021-00259-4 ◽

2021 ◽

Vol 9 (1) ◽

Author(s):

Sunada Khadka ◽

Kenisha Arthur ◽

Yasaman Barekatain ◽

Eliot Behr ◽

Mykia Washington ◽

...

Keyword(s):

Culture Media ◽

Single Agent ◽

Glioma Cells ◽

Tca Cycle ◽

Redox Status ◽

Metabolomic Profiling ◽

The Tca Cycle ◽

Selective Sensitivity

Abstract Background Reprogramming of metabolic pathways is crucial to satisfy the bioenergetic and biosynthetic demands and maintain the redox status of rapidly proliferating cancer cells. In tumors, the tricarboxylic acid (TCA) cycle generates biosynthetic intermediates and must be replenished (anaplerosis), mainly from pyruvate and glutamine. We recently described a novel enolase inhibitor, HEX, and its pro-drug POMHEX. Since glycolysis inhibition would deprive the cell of a key source of pyruvate, we hypothesized that enolase inhibitors might inhibit anaplerosis and synergize with other inhibitors of anaplerosis, such as the glutaminase inhibitor, CB-839. Methods We analyzed polar metabolites in sensitive (ENO1-deleted) and resistant (ENO1-WT) glioma cells treated with enolase and glutaminase inhibitors. We investigated whether sensitivity to enolase inhibitors could be attenuated by exogenous anaplerotic metabolites. We also determined the synergy between enolase inhibitors and the glutaminase inhibitor CB-839 in glioma cells in vitro and in vivo in both intracranial and subcutaneous tumor models. Results Metabolomic profiling of ENO1-deleted glioma cells treated with the enolase inhibitor revealed a profound decrease in the TCA cycle metabolites with the toxicity reversible upon exogenous supplementation of supraphysiological levels of anaplerotic substrates, including pyruvate. ENO1-deleted cells also exhibited selective sensitivity to the glutaminase inhibitor CB-839, in a manner rescuable by supplementation of anaplerotic substrates or plasma-like media PlasmaxTM. In vitro, the interaction of these two drugs yielded a strong synergistic interaction but the antineoplastic effects of CB-839 as a single agent in ENO1-deleted xenograft tumors in vivo were modest in both intracranial orthotopic tumors, where the limited efficacy could be attributed to the blood-brain barrier (BBB), and subcutaneous xenografts, where BBB penetration is not an issue. This contrasts with the enolase inhibitor HEX, which, despite its negative charge, achieved antineoplastic effects in both intracranial and subcutaneous tumors. Conclusion Together, these data suggest that at least for ENO1-deleted gliomas, tumors in vivo—unlike cells in culture—show limited dependence on glutaminolysis and instead primarily depend on glycolysis for anaplerosis. Our findings reinforce the previously reported metabolic idiosyncrasies of in vitro culture and suggest that cell culture media nutrient composition more faithful to the in vivo environment will more accurately predict in vivo efficacy of metabolism targeting drugs.

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Homozygous MTAP deletion in primary human glioblastoma is not associated with elevation of methylthioadenosine

Nature Communications ◽

10.1038/s41467-021-24240-3 ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Yasaman Barekatain ◽

Jeffrey J. Ackroyd ◽

Victoria C. Yan ◽

Sunada Khadka ◽

Lin Wang ◽

...

Keyword(s):

Clinical Relevance ◽

Homozygous Deletion ◽

In Vitro Models ◽

Arginine Methyltransferase ◽

Human Glioblastoma ◽

Primary Glioblastoma ◽

Methylthioadenosine Phosphorylase ◽

Metabolomic Profiling

AbstractHomozygous deletion of methylthioadenosine phosphorylase (MTAP) in cancers such as glioblastoma represents a potentially targetable vulnerability. Homozygous MTAP-deleted cell lines in culture show elevation of MTAP’s substrate metabolite, methylthioadenosine (MTA). High levels of MTA inhibit protein arginine methyltransferase 5 (PRMT5), which sensitizes MTAP-deleted cells to PRMT5 and methionine adenosyltransferase 2A (MAT2A) inhibition. While this concept has been extensively corroborated in vitro, the clinical relevance relies on exhibiting significant MTA accumulation in human glioblastoma. In this work, using comprehensive metabolomic profiling, we show that MTA secreted by MTAP-deleted cells in vitro results in high levels of extracellular MTA. We further demonstrate that homozygous MTAP-deleted primary glioblastoma tumors do not significantly accumulate MTA in vivo due to metabolism of MTA by MTAP-expressing stroma. These findings highlight metabolic discrepancies between in vitro models and primary human tumors that must be considered when developing strategies for precision therapies targeting glioblastoma with homozygous MTAP deletion.

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Preclinical investigation of a small molecule inhibitor of p300/CBP reveals efficacy in patient-derived prostate tumor explants.

Journal of Clinical Oncology ◽

10.1200/jco.2019.37.15_suppl.e16534 ◽

2019 ◽

Vol 37 (15_suppl) ◽

pp. e16534-e16534 ◽

Cited By ~ 1

Author(s):

Lisa Butler ◽

Swati Irani ◽

Margaret Centenera ◽

Natalie Ryan ◽

Neil Pegg ◽

...

Keyword(s):

Prostate Cancer ◽

Cancer Cells ◽

Small Molecule ◽

Single Agent ◽

Specific Antigen ◽

Resistance Mechanisms ◽

Prostate Cancer Cells ◽

In Vivo Models

e16534 Background: Growth and survival of prostate cancer cells are initially dependent upon androgens, and androgen deprivation therapy (ADT) is used to control tumor growth. Unfortunately, resistance to ADT inevitably occurs, and patients relapse with lethal castrate-resistant prostate cancer (CRPC). Increased expression of the androgen receptor (AR) and constitutively active AR variants are hallmarks of CRPC, and treatments targeting aberrant AR signaling are urgently required. CCS1477 is an inhibitor of p300/CBP currently in a Phase I/IIa study for CRPC. CCS1477 enhances degradation of numerous cellular proteins including the AR and AR variants in prostate cancer cells. Our preclinical studies with this compound demonstrated potent single-agent efficacy of CCS1477 using in vitro and in vivo models of prostate cancer and, when used in combination, CCS1477 enhances the efficacy of enzalutamide, a clinical AR antagonist. Understanding the response of clinical tumors to CCS1477, and their potential adaptive evolution, is essential to personalize treatment and predict potential resistance mechanisms. Methods: To assess CCS1477 in human disease, we used a unique model in which clinical prostate tumors from radical prostatectomy are cultured as explants with maintenance of tissue integrity, cell proliferation and androgen signaling. Tumors from 13 patients were cultured in the absence or presence of CCS1477 (10µM) or enzalutamide (10µM) for 48 or 72 hours; micromolar doses were selected to account for altered small molecule uptake and penetration into tissues compared to cell lines, as previously reported. Proliferation, apoptosis and androgen signaling were all analyzed post-culture. Results: Whereas the tumor explants exhibited highly heterogenous proliferative responses to enzalutamide, tumors from all patients exhibited a marked antiproliferative response to CCS1477 (mean reduction in Ki67 immunoreactivity of > 90% compared to vehicle control; p < 0.0005). Culture with CCS1477 was associated with repression of androgen signaling in the prostate tissues, measured by expression and secretion of the clinical biomarker prostate specific antigen (PSA). Conclusions: The consistent and pronounced efficacy of CCS1477 in this patient-derived model would support further investigation of this class of epigenetic agents in the castrate-sensitive prostate cancer setting.

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An in vivo model to evaluate donor-dependent cytokine release in response to single-agent or combination immune-oncology therapies.

Journal of Clinical Oncology ◽

10.1200/jco.2020.38.15_suppl.3114 ◽

2020 ◽

Vol 38 (15_suppl) ◽

pp. 3114-3114

Author(s):

Kyle Draheim ◽

Jing Jiao ◽

Jiwon Yang ◽

Danying Cai ◽

Mingshan Cheng ◽

...

Keyword(s):

Cancer Cells ◽

Checkpoint Inhibitors ◽

Single Agent ◽

Tumor Burden ◽

Cytokine Release ◽

Humanized Mouse ◽

Human Pbmc ◽

Immune Oncology

3114 Background: Although immune-oncology therapies such as checkpoint inhibitor, bi-specific antibody and CAR-T cell therapies are successfully used for cancer therapy, they can have very severe adverse effects such as cytokine release syndrome (CRS). The animal models and in vitro human PBMC assays presently in use do not reliably predict CRS in patients. Currently, the only widely accepted predictors of CRS are cancer burden and therapeutic dose. Despite this, most pre-clinical assays that evaluate CRS do not incorporate cancer cells and the safety of drug combinations has not been widely explored. A predictive assay that identifies patient/cancer/therapy combinations at risk for developing CRS upfront in addition to treatment efficacy would improve the safety of immune-oncology drug development. Methods: We have developed sensitive in vivo humanized mouse models for quantitating CRS that are rapid, reproducible and able to show variation among PBMC donors. The NSG mouse and its derivatives are engrafted with cancer cells and human PBMCs. Mice are then dosed with checkpoint inhibitors or bi-specific antibodies as a single therapy or in combination. Cytokine release is evaluated 2-6 hours post dosing. This assay can be modified to also evaluate efficacy by using luciferase labeled cancer cells and monitoring tumor burden using the Xenogen IVIS imaging system. Results: For all therapy groups, each cytokine tested (including human IFN-γ, IL-2, IL-6, IL-10 and TNF) was upregulated 2-6 hours after drug treatment, but different PBMC donors had various cytokines release levels. Cytokine release levels correlated with a dose response, PBMC engraftment levels and tumor burden. We can demonstrate additive and synergistic cytokine release in the combination treated groups and compare efficacy versus single agents. Our in vivo method was able to determine CRS missed in the in vitro testing method. Conclusions: We have developed a rapid, sensitive and reproducible novel in vivo PBMC humanized mouse model that can differentiate human PBMC donors based on individual safety response to single agent and combination therapeutics of immune checkpoint inhibitors and bispecific T-cell-engaging antibodies. Additionally, this assay can utilize luciferase labelled cell lines to measure treatment efficacy. Using this assay, we can potentially evaluate both cytokine release and efficacy of current immune-oncology therapies as single agents and in combination. This assay has immediate utility in current and future drug development.

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Repression of LKB1 by miR-17∼92 sensitizes MYC-dependent lymphoma to biguanide treatment

10.1101/2019.12.20.883025 ◽

2019 ◽

Cited By ~ 1

Author(s):

Said Izreig ◽

Alexandra Gariepy ◽

Ariel O. Donayo ◽

Gaëlle Bridon ◽

Daina Avizonis ◽

...

Keyword(s):

Cancer Cells ◽

Tumor Cells ◽

Human Cancer ◽

Tca Cycle ◽

Mirna Cluster ◽

Lymphoma Cells ◽

Ampk Signaling ◽

Potential Biomarker

AbstractCancer cells display metabolic plasticity to survive metabolic and energetic stresses in the tumor microenvironment, prompting the need for tools to target tumor metabolism. Cellular adaptation to energetic stress is coordinated in part by signaling through the Liver Kinase B1 (LKB1)-AMP-activated protein kinase (AMPK) pathway. Reducing LKB1-AMPK signaling exposes metabolic vulnerabilities in tumor cells with potential for therapeutic targeting. Here we describe that miRNA-mediated silencing of LKB1 (mediated by the oncogenic miRNA cluster miR-17∼92) confers sensitivity of lymphoma cells to mitochondrial inhibition by biguanides. Using both classic (phenformin) and novel (IM156) biguanides, we demonstrate that Myc+ lymphoma cells with elevated miR-17∼92 expression display increased sensitivity to biguanide treatment both in cell viability assays in vitro and tumor growth assays in vivo. This increased biguanide sensitivity is driven by miR-17-dependent silencing of LKB1, which results in reduced AMPK activation in response to bioenergetic stress. Mechanistically, biguanide treatment inhibits TCA cycle metabolism and mitochondrial respiration in miR-17∼92-expressing tumor cells, targeting their metabolic vulnerability. Finally, we demonstrate a direct correlation between miR-17∼92 expression and biguanide sensitivity in human cancer cells. Our results identify miR-17∼92 expression as a potential biomarker for biguanide sensitivity in hematological malignancies and solid tumors.One Sentence SummarymiR-17∼92 expression in Myc+ tumors sensitizes cancer cells to biguanide treatment by disrupting bioenergetic stability in lymphoma cells.

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OTME-9. Comprehensive Metabolic Profiling Of high MYC Medulloblastoma Reveals Key Differences Between In Vitro And In Vivo Glucose And Glutamine Usage

Neuro-Oncology Advances ◽

10.1093/noajnl/vdab070.060 ◽

2021 ◽

Vol 3 (Supplement_2) ◽

pp. ii15-ii15

Author(s):

Khoa Pham ◽

Brad Poore ◽

Allison Hanaford ◽

Micah J Maxwell ◽

Heather Sweeney ◽

...

Keyword(s):

Cancer Cells ◽

Tca Cycle ◽

Genetic Mutations ◽

Metabolic Profiles ◽

Normal Brain ◽

Genomic Amplification ◽

Cells In Culture ◽

Orthotopic Xenograft

Abstract Reprograming of cellular metabolism is a hallmark of cancer. The metabolic alterations in cancer cells is not only defined by series of genetic mutations, but also reflecting the crosstalk between cancer cells and other factors in the microenvironment. Altering metabolism allows cancer cells to overcome unfavorable conditions, to proliferate and invade. Medulloblastoma is the most common malignant brain tumor of children. Genomic amplification of MYC is a hallmark of a subset of poor-prognosis medulloblastoma. However, the metabolism of high MYC amplified medulloblastoma subgroup remains underexplored. We performed comprehensive metabolic studies of human MYC-amplified medulloblastoma by comparing the metabolic profiles of tumor cells in different environments – in vitro, in flank xenografts and in orthotopic xenografts. Principal component analysis showed that the metabolic profiles of brain and flank high-MYC medulloblastoma tumors clustered closely together and separated away from normal brain and the high-MYC medulloblastoma cells in culture. Compared to normal brain, MYC-amplified medulloblastoma orthotopic xenograft tumors showed upregulation of nucleotide, hexosamine biosynthetic pathway (HBP), TCA cycle, and amino acid and glutathione pathways. There was significantly higher glucose up taking and usage in orthotopic xenograft tumor compared to flank xenograft and cells in culture. The data demonstrated that glucose was the main carbon source for the glutamate, glutamine and glutathione synthesis through the TCA cycle. The glutaminase ii pathway was the main pathway utilizing glutamine in MYC-amplified medulloblastoma in vivo. Glutathione was found as the most abundant upregulated metabolite. Glutamine derived glutathione was mainly synthesized through glutamine transaminase K (GTK) enzyme in vivo. In conclusion, we demonstrated that high MYC medulloblastoma adapt to different environments by altering its metabolic pathways despite carrying the same genetic mutations. Glutamine antagonists may have therapeutic applications in human patients.

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Distinct Metabolic Dependency of Normal and Leukemic Cells in a Mouse Model

Blood ◽

10.1182/blood.v118.21.759.759 ◽

2011 ◽

Vol 118 (21) ◽

pp. 759-759

Author(s):

Rushdia Z. Yusuf ◽

Sanket S. Acharya ◽

Vionnie Yu ◽

Borja Saez ◽

Mildred Duvet ◽

...

Keyword(s):

Bone Marrow ◽

Conflicts Of Interest ◽

Tca Cycle ◽

Leukemic Cells ◽

Mouse Bone Marrow ◽

Metabolomic Profiling ◽

Glycolysis Pathway ◽

Rate Limiting

Abstract Abstract 759 We hypothesized that metabolic differences between leukemia initiating cells and their normal counterparts represent a vulnerability in the leukemia initiating cell, which can be therapeutically exploited. To test this hypothesis, we used the MLL-AF9 acute myeloid leukemia (AML) model in mice. Actin-DsRed mouse bone marrow transduced with MLL-AF9 expressing retrovirus was used to produce serially transplantable leukemia. Leukemic granulocyte-monocyte precursors (L-GMPs), defined by others to be the leukemia initiating cells were flow sorted from secondary recipient mice and compared with normal GMPs (N-GMPs) from actin Ds-Red mice. Gene expression profiling, metabolomic profiling via liquid chromatography- mass spectrometry and an in vitro shRNA screen were used to identify metabolic pathways preferentially activated in leukemia initiating cells. Of 1574 defined metabolic enzymes, 44 were found to be differentially expressed between L-GMPs and their normal counterparts (N-GMPs). These together with 117 classic rate limiting enzymes were subjected to shRNA knockdown in vitro. Metabolomic profiling of both cell populations was used to corroborate findings from shRNA knockdowns. L-GMPs and N-GMPs were transduced with lentivirus expressing shRNAs of interest (5 shRNAs per gene) in a 384 well format, selected with puromycin and cultured for 72–96 hours in the presence of GFP-positive primary bone marrow stroma. The number of cells in each well at the end of this experiment was quantitated using an Image Xpress microscope. Genes, the knockdown of which by at least two independent shRNAs produced a two fold or more decrease in L-GMPs as compared to control wells and did not similarly decrease N-GMPs, were chosen for in vivo validation. Ten genes in the glycolysis pathway and TCA cycle, fatty acid metabolism and detoxification, and ketohexokinase were identified. Ketohexokinase, a rate-limiting enzyme in fructose metabolism was particularly potent and of interest given its potential to be exploited therapeutically. In vivo assessment of its relative ability to inhibit malignant versus normal hematopoietic cells is ongoing. These studies provide preliminary support for the hypothesis that specific metabolic circuits are differentially active in leukemia initiating cells in MLL-AF9 AML and may represent unique points of vulnerability that can be targeted therapeutically. Authors 1 and 2 contributed equally. Authors 3 and 4 contributed equally. Disclosures: No relevant conflicts of interest to declare.

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Methylthioadenosine is Not Dramatically Elevated in MTAP-Homozygous Deleted Primary Glioblastomas

10.1101/769885 ◽

2019 ◽

Author(s):

Yasaman Barekatain ◽

Victoria C. Yan ◽

Jeffrey J. Ackroyd ◽

Anton H. Poral ◽

Theresa Tran ◽

...

Keyword(s):

Cancer Cells ◽

Stromal Cells ◽

Homozygous Deletion ◽

Human Tumors ◽

Normal Brain ◽

List Type ◽

Human Glioblastoma ◽

Frequent Event

In BriefThe co-deletion of MTAP in the CDKN2A locus is a frequent event in diverse cancers including glioblastoma. Recent publications report that significant accumulations of the MTAP substrate, methylthioadenosine (MTA), can sensitize MTAP-deleted cancer cells to novel inhibitors of PRMT5 and MAT2A for targeted therapy against tumors with this particular genetic alteration. In this work, using comprehensive metabolomic profiling, we show that MTA is primarily secreted, resulting in exceedingly high levels of extracellular MTA in vitro. We further show that primary human glioblastoma tumors minimally accumulate MTA in vivo, which is likely explained by the metabolism of MTA by MTAP-competent stromal cells. Together, these data challenge whether the metabolic conditions required for therapies to exploit vulnerabilities associated MTAP deletions are present in primary human tumors, questioning their translational efficacy in the clinic.HighlightsMethylthioadenosine (MTA) is elevated in MTAP-deleted cancer cells in vitro, which provides a selective vulnerability to PRMT5 and MAT2A inhibitorsAccumulation of MTA in MTAP-deleted cancer cells is predominately extracellular, suggesting active secretion of MTA.MTAP-deleted primary human glioblastoma tumors show minimal intratumoral elevations of MTA, which is likely explained by secretion and metabolism by MTAP-competent stromal cells.SUMMARYHomozygous deletion of the CDK2NA locus frequently results in co-deletion of methylthioadenosine phosphorylase (MTAP) in many fatal cancers such as glioblastoma multiforme (GBM), resulting in elevations of the substrate metabolite, methylthioadenosine (MTA). To capitalize on such accumulations, therapeutic targeting of protein arginine methyltransferase 5 (PRMT5) and methionine adenosyl transferase (MAT2A) are ongoing. While extensively corroborated in vitro, the clinical efficacy of these strategies ultimately relies on equally significant accumulations of MTA in human tumors. Here, we show that in vitro accumulation of MTA is a predominately extracellular phenomenon, indicating secretion of MTA from MTAP-deleted cells. In primary human GBMs, we find that MTA levels are not significantly higher in MTAP-deleted compared to MTAP-intact tumors or normal brain tissue. Together, these findings highlight the metabolic discrepancies between in vitro models and primary human tumors and should thus be carefully considered in the development of the precision therapies targeting MTAP-homozygous deleted GBM.

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