MYC disrupts transcriptional and metabolic circadian oscillations in cancer and promotes enhanced biosynthesis.

The molecular circadian clock, which controls rhythmic 24-hour oscillation of genes, proteins, and metabolites in healthy tissues, is disrupted across many human cancers. Deregulated expression of the MYC oncoprotein has been shown to alter expression of molecular clock genes, leading to a disruption of molecular clock oscillation across cancer types. It remains unclear what benefit cancer cells gain from suppressing clock oscillation, and how this loss of molecular clock oscillation impacts global gene expression and metabolism in cancer. We hypothesized that MYC or its paralog N-MYC (collectively termed MYC herein) suppress oscillation of gene expression and metabolism to upregulate pathways involved in biosynthesis in a static, non-oscillatory fashion. To test this, cells from distinct cancer types with inducible MYC were examined, using time-series RNA-sequencing and metabolomics, to determine the extent to which MYC activation disrupts global oscillation of genes, gene expression pathways, and metabolites. We focused our analyses on genes, pathways, and metabolites that changed in common across multiple cancer cell line models. We report here that MYC disrupted over 85% of oscillating genes, while instead promoting enhanced ribosomal and mitochondrial biogenesis and suppressed cell attachment pathways. Notably, when MYC is activated, biosynthetic programs that were formerly circadian flipped to being upregulated in an oscillation-free manner. Further, activation of MYC ablates the oscillation of nutrient transporter proteins while greatly upregulating transporter expression, cell surface localization, and intracellular amino acid pools. Finally, we report that MYC disrupts metabolite oscillations and the temporal segregation of amino acid metabolism from nucleotide metabolism. Our results demonstrate that MYC disruption of the molecular circadian clock releases metabolic and biosynthetic processes from circadian control, which may provide a distinct advantage to cancer cells.

Evolving concepts in meningioma management in the era of genomics.

Meningioma is the most common type of primary brain tumor. Surgical resection followed by surveillance is the first-line treatment for the majority of symptomatic meningiomas; however, recent advances in molecular sequencing, DNA methylation, proteomics, and single-cell sequencing provide insights into further characterizing this heterogeneous group of tumors with a wide range of prognoses. A subset of these tumors are highly aggressive and cause severe morbidity and mortality. Therefore, identifying those individuals with a poor prognosis and intervening are critical. This review aims to help readers interpret the molecular profiling of meningiomas to identify patients with worse prognoses and guide the management and strategy for surveillance.

A multi-center, clinical analysis of IDH-mutant gliomas, WHO Grade 4: implications for prognosis and clinical trial design.

PURPOSE: Mutations in the Isocitrate Dehydrogenase (IDH) genes, IDH1 or IDH2, define a group of adult diffuse gliomas associated with a younger age at diagnosis and better prognosis than IDH wild-type glioblastoma. Within IDH mutant gliomas, a small fraction of astrocytic tumors present with grade 4 histologic features and poor prognosis. In molecular studies, homozygous deletion of CDKN2A/B is independently predictive of poor prognosis and short survival. As a consequence, 2021 WHO classification now also recognizes this molecular feature, CDKN2A/B deletion, as sufficient for classifying an astrocytoma as IDH-mutant, WHO Grade 4, regardless of histological grading. Here, we investigate outcomes of patients with WHO Grade 4 IDH-mutant astrocytoma both with and without CDKN2A/B deletion, to compare these groups and evaluate clinical and radiographic factors that contribute to survival. METHODS: We retrospectively identified 79 patients with IDH-mutant astrocytoma with CDKN2A/B deletion detected at initial diagnosis across five international institutions as well as a comparison group of 51 patients with IDH-mutant, astrocytoma, histologically Grade 4 without detectable CDKN2A/B deletion. We assembled clinical and radiographic features for all patients. RESULTS: We find that CDKN2A/B deletion was associated with significantly worse overall survival (OS; p = 0.0004) and progression-free survival (PFS; p = 0.0026), with median OS of 5.0 years and PFS of 3.0 years, compared to 10.1 and 5.0 years for tumors with a grade 4 designation based only on histologic criteria. Multivariate analysis confirmed CDKN2A/B deletion as a strong negative prognosticator for both OS (HR = 3.51, p < 0.0001) and PFS (HR = 2.35, p = 0.00095). In addition, in tumors with CDKN2A/B deletion, preoperative contrast enhancement is a significant predictor of worse OS (HR 2.19, 95% CI 1.22-3.93, p = 0.0090) and PFS (HR = 1.74, 95% CI = 1.02-2.97, p = 0.0420). CONCLUSIONS: These findings underscore the severe prognostic impact of CDKN2A/B deletion in IDH-mutant astrocytomas and highlight the need for further refinement of tumor prognostic categorization. Our results provide a key benchmark of baseline patient outcomes for therapeutic trials, underscoring the importance of CDKN2A/B status assessment, in addition to histologic grading, in clinical trial design and therapeutic decision-making for IDH-mutant astrocytoma patients.

Comparison of type B dissection by open, endovascular, and medical treatments.

OBJECTIVE: This study aimed to address the shortcomings of previous clinical trials that were inadequate to prove the superiority of thoracic endovascular aortic repair (TEVAR) in managing type B aortic dissection (TBAD) over open surgery (OS) or best medical treatment (BMT). The comparative effectiveness of these three treatments was analyzed using data of the National Inpatient Sample, a large U.S. database including patients from 4378 hospitals. METHODS: Adult patients diagnosed with a primary or secondary TBAD in the years 2005 to 2012 were included for analysis. Patients who had aortic aneurysm or received cardioplegia, valve repair, or operations on vessels of the heart were excluded. A three-category propensity score was created by using a multinomial logistic regression model, a three-way matching algorithm for 1:1:1 matching was applied, and a parallel outcome comparison between the three matched treatment groups was performed. RESULTS: Of a total of 54,971 patients included in the study, we matched 17,211 into three equal-size treatment groups (OS, 5755; TEVAR, 5695; BMT, 5761). No significant difference in the 22 baseline covariates was found in the matched cohort. We found TEVAR to have a much lower mortality rate than OS (odds ratio [OR], 0.60; 95% confidence interval [CI], 0.46-0.79) or BMT (OR, 0.62; 95% CI, 0.47-0.83). Mortality rates between OS and BMT were similar (OR, 0.97; 95% CI, 0.74-1.27). We also found TEVAR to have a lower complication rate, shorter hospitalization, and lower medical cost compared with OS. CONCLUSIONS: TEVAR is superior to BMT or OS for treatment of TBAD in terms of mortality, complications, and cost.

MYC and metabolism on the path to cancer.

The MYC proto-oncogene is frequently deregulated in human cancers, activating genetic programs that orchestrate biological processes to promote growth and proliferation. Altered metabolism characterized by heightened nutrients uptake, enhanced glycolysis and glutaminolysis and elevated fatty acid and nucleotide synthesis is the hallmark of MYC-driven cancer. Recent evidence strongly suggests that Myc-dependent metabolic reprogramming is critical for tumorigenesis, which could be attenuated by targeting specific metabolic pathways using small drug-like molecules. Understanding the complexity of MYC-mediated metabolic re-wiring in cancers as well as how MYC cooperates with other metabolic drivers such as mammalian target of rapamycin (mTOR) will provide translational opportunities for cancer therapy.

MYC, Metabolic Synthetic Lethality, and Cancer.

The MYC oncogene plays a pivotal role in the development and progression of human cancers. It encodes a transcription factor that has broad reaching effects on many cellular functions, most importantly in driving cell growth through regulation of genes involved in ribosome biogenesis, metabolism, and cell cycle. Upon binding DNA with its partner MAX, MYC recruits factors that release paused RNA polymerases to drive transcription and amplify gene expression. At physiologic levels of MYC, occupancy of high-affinity DNA-binding sites drives 'house-keeping' metabolic genes and those involved in ribosome and mitochondrial biogenesis for biomass accumulation. At high oncogenic levels of MYC, invasion of low-affinity sites and enhancer sequences alter the transcriptome and cause metabolic imbalances, which activates stress response and checkpoints such as p53. Loss of checkpoints unleashes MYC's full oncogenic potential to couple metabolism with neoplastic cell growth and division. Cells that overexpress MYC, however, are vulnerable to metabolic perturbations that provide potential new avenues for cancer therapy.

Widespread Neuroanatomical Integration and Distinct Electrophysiological Properties of Glioma-Innervating Neurons.

Gliomas are the most common malignant primary brain tumors and are often associated with severe neurological deficits and mortality. Unlike many cancers, gliomas rarely metastasize outside the brain, indicating a possible dependency on unique features of brain microenvironment. Synapses between neurons and glioma cells exist, suggesting that glioma cells rely on neuronal inputs and synaptic signaling for proliferation. Yet, the locations and properties of neurons that innervate gliomas have remained elusive. In this study, we utilized transsynaptic tracing with a pseudotyped, glycoprotein-deleted rabies virus to specifically infect TVA and glycoprotein-expressing human glioblastoma cells in an orthotopic xenograft mouse model, allowing us to identify the neurons that form synapses onto the gliomas. Comprehensive whole-brain mapping revealed that these glioma-innervating neurons (GINs) consistently arise at brain regions, including diverse neuromodulatory centers and specific cortical layers, known to project to the glioma locations. Molecular profiling revealed that these long-range cortical GINs are predominantly glutamatergic, and subsets express both glutamatergic and GABAergic markers, whereas local striatal GINs are largely GABAergic. Electrophysiological studies demonstrated that while GINs share passive intrinsic properties with cortex-innervating neurons, their action potential waveforms are altered. Our study introduces a novel method for identifying and mapping GINs and reveals their consistent integration into existing location-dependent neuronal network involving diverse neurotransmitters and neuromodulators. The observed intrinsic electrophysiological differences in GINs lay the groundwork for future investigations into how these alterations may correspond with the postsynaptic characteristics of glioma cells. Significance: We have developed a novel system utilizing rabies virus-based monosynaptic tracing to directly visualize neurons that synapse onto human glioma cells implanted in mouse brain. This approach enables the mapping and quantitative analysis of these glioma-innervating neurons (GINs) in the entire mouse brain and overcomes previous barriers of molecular and electrophysiological analysis of these neurons due to the inability to identify them. Our findings indicate that GINs integrate into existing neural networks in a location-specific manner. Long-range GINs are mostly glutamatergic, with a subset expressing both glutamatergic and GABAergic markers and local striatal GINs are GABAergic, highlighting a complex neuromodulatory profile. Additionally, GINs exhibit unique action potential characteristics, distinct from similarly selected neurons in non-tumor-bearing brains. This study provides new insights into neuronal adaptations in response to forming putative synapses onto glioma, elucidating the intricate synaptic relationship between GINs and gliomas.

MYC disrupts transcriptional and metabolic circadian oscillations in cancer and promotes enhanced biosynthesis.

The molecular circadian clock, which controls rhythmic 24-hour oscillation of genes, proteins, and metabolites in healthy tissues, is disrupted across many human cancers. Deregulated expression of the MYC oncoprotein has been shown to alter expression of molecular clock genes, leading to a disruption of molecular clock oscillation across cancer types. It remains unclear what benefit cancer cells gain from suppressing clock oscillation, and how this loss of molecular clock oscillation impacts global gene expression and metabolism in cancer. We hypothesized that MYC or its paralog N-MYC (collectively termed MYC herein) suppress oscillation of gene expression and metabolism to upregulate pathways involved in biosynthesis in a static, non-oscillatory fashion. To test this, cells from distinct cancer types with inducible MYC were examined, using time-series RNA-sequencing and metabolomics, to determine the extent to which MYC activation disrupts global oscillation of genes, gene expression pathways, and metabolites. We focused our analyses on genes, pathways, and metabolites that changed in common across multiple cancer cell line models. We report here that MYC disrupted over 85% of oscillating genes, while instead promoting enhanced ribosomal and mitochondrial biogenesis and suppressed cell attachment pathways. Notably, when MYC is activated, biosynthetic programs that were formerly circadian flipped to being upregulated in an oscillation-free manner. Further, activation of MYC ablates the oscillation of nutrient transporter proteins while greatly upregulating transporter expression, cell surface localization, and intracellular amino acid pools. Finally, we report that MYC disrupts metabolite oscillations and the temporal segregation of amino acid metabolism from nucleotide metabolism. Our results demonstrate that MYC disruption of the molecular circadian clock releases metabolic and biosynthetic processes from circadian control, which may provide a distinct advantage to cancer cells.

Misregulation of Drosophila Myc Disrupts Circadian Behavior and Metabolism.

Drosophila Myc (dMyc) is highly conserved and functions as a transcription factor similar to mammalian Myc. We previously found that oncogenic Myc disrupts the molecular clock in cancer cells. Here, we demonstrate that misregulation of dMyc expression affects Drosophila circadian behavior. dMyc overexpression results in a high percentage of arrhythmic flies, concomitant with increases in the expression of clock genes cyc, tim, cry, and cwo. Conversely, flies with hypomorphic mutations in dMyc exhibit considerable arrhythmia, which can be rescued by loss of dMnt, a suppressor of dMyc activity. Metabolic profiling of fly heads revealed that loss of dMyc and its overexpression alter steady-state metabolite levels and have opposing effects on histidine, the histamine precursor, which is rescued in dMyc mutants by ablation of dMnt and could contribute to effects of dMyc on locomotor behavior. Our results demonstrate a role of dMyc in modulating Drosophila circadian clock, behavior, and metabolism.

The MYC Oncogene Cooperates with Sterol-Regulated Element-Binding Protein to Regulate Lipogenesis Essential for Neoplastic Growth.

Lipid metabolism is frequently perturbed in cancers, but the underlying mechanism is unclear. We present comprehensive evidence that oncogene MYC, in collaboration with transcription factor sterol-regulated element-binding protein (SREBP1), regulates lipogenesis to promote tumorigenesis. We used human and mouse tumor-derived cell lines, tumor xenografts, and four conditional transgenic mouse models of MYC-induced tumors to show that MYC regulates lipogenesis genes, enzymes, and metabolites. We found that MYC induces SREBP1, and they collaborate to activate fatty acid (FA) synthesis and drive FA chain elongation from glucose and glutamine. Further, by employing desorption electrospray ionization mass spectrometry imaging (DESI-MSI), we observed in vivo lipidomic changes upon MYC induction across different cancers, for example, a global increase in glycerophosphoglycerols. After inhibition of FA synthesis, tumorigenesis was blocked, and tumors regressed in both xenograft and primary transgenic mouse models, revealing the vulnerability of MYC-induced tumors to the inhibition of lipogenesis.

MYC, Metabolism, and Cancer.

UNLABELLED: The MYC oncogene encodes a transcription factor, MYC, whose broad effects make its precise oncogenic role enigmatically elusive. The evidence to date suggests that MYC triggers selective gene expression amplification to promote cell growth and proliferation. Through its targets, MYC coordinates nutrient acquisition to produce ATP and key cellular building blocks that increase cell mass and trigger DNA replication and cell division. In cancer, genetic and epigenetic derangements silence checkpoints and unleash MYC's cell growth- and proliferation-promoting metabolic activities. Unbridled growth in response to deregulated MYC expression creates dependence on MYC-driven metabolic pathways, such that reliance on specific metabolic enzymes provides novel targets for cancer therapy. SIGNIFICANCE: MYC's expression and activity are tightly regulated in normal cells by multiple mechanisms, including a dependence upon growth factor stimulation and replete nutrient status. In cancer, genetic deregulation of MYC expression and loss of checkpoint components, such as TP53, permit MYC to drive malignant transformation. However, because of the reliance of MYC-driven cancers on specific metabolic pathways, synthetic lethal interactions between MYC overexpression and specific enzyme inhibitors provide novel cancer therapeutic opportunities.

MYC Disrupts the Circadian Clock and Metabolism in Cancer Cells.

The MYC oncogene encodes MYC, a transcription factor that binds the genome through sites termed E-boxes (5'-CACGTG-3'), which are identical to the binding sites of the heterodimeric CLOCK-BMAL1 master circadian transcription factor. Hence, we hypothesized that ectopic MYC expression perturbs the clock by deregulating E-box-driven components of the circadian network in cancer cells. We report here that deregulated expression of MYC or N-MYC disrupts the molecular clock in vitro by directly inducing REV-ERBα to dampen expression and oscillation of BMAL1, and this could be rescued by knockdown of REV-ERB. REV-ERBα expression predicts poor clinical outcome for N-MYC-driven human neuroblastomas that have diminished BMAL1 expression, and re-expression of ectopic BMAL1 in neuroblastoma cell lines suppresses their clonogenicity. Further, ectopic MYC profoundly alters oscillation of glucose metabolism and perturbs glutaminolysis. Our results demonstrate an unsuspected link between oncogenic transformation and circadian and metabolic dysrhythmia, which we surmise to be advantageous for cancer.

Targeted inhibition of tumor-specific glutaminase diminishes cell-autonomous tumorigenesis.

Glutaminase (GLS), which converts glutamine to glutamate, plays a key role in cancer cell metabolism, growth, and proliferation. GLS is being explored as a cancer therapeutic target, but whether GLS inhibitors affect cancer cell-autonomous growth or the host microenvironment or have off-target effects is unknown. Here, we report that loss of one copy of Gls blunted tumor progression in an immune-competent MYC-mediated mouse model of hepatocellular carcinoma. Compared with results in untreated animals with MYC-induced hepatocellular carcinoma, administration of the GLS-specific inhibitor bis-2-(5-phenylacetamido-1,3,4-thiadiazol-2-yl)ethyl sulfide (BPTES) prolonged survival without any apparent toxicities. BPTES also inhibited growth of a MYC-dependent human B cell lymphoma cell line (P493) by blocking DNA replication, leading to cell death and fragmentation. In mice harboring P493 tumor xenografts, BPTES treatment inhibited tumor cell growth; however, P493 xenografts expressing a BPTES-resistant GLS mutant (GLS-K325A) or overexpressing GLS were not affected by BPTES treatment. Moreover, a customized Vivo-Morpholino that targets human GLS mRNA markedly inhibited P493 xenograft growth without affecting mouse Gls expression. Conversely, a Vivo-Morpholino directed at mouse Gls had no antitumor activity in vivo. Collectively, our studies demonstrate that GLS is required for tumorigenesis and support small molecule and genetic inhibition of GLS as potential approaches for targeting the tumor cell-autonomous dependence on GLS for cancer therapy.