Biology subjects

Wellen, K.

Publications and source records attributed to Wellen, K..

6 recordsLinked to original sources

bioRxiv2025

Mitochondrial ACSS1 Links Acetate Metabolism to Pyrimidine Biosynthesis in Nutrient-Stressed B-Cell Lymphomas

Acetate serves as an alternative carbon source in nutrient-limited tumors, yet its role in supporting nucleotide biosynthesis remains poorly understood. Here, we identify the mitochondrial enzyme ACSS1 as a key metabolic driver in mantle cell lymphoma (MCL), diffuse large B-cell lymphoma (DLBCL), and chronic lymphocytic leukemia (CLL). ACSS1 is frequently overexpressed and catalyzes the conversion of acetate to mitochondrial acetyl-CoA, sustaining oxidative metabolism and biosynthesis under nutrient stress. Genetic silencing of ACSS1 impairs mitochondrial respiration and disrupts acetate incorporation into acetyl-CoA, TCA cycle intermediates, glutamate, and aspartate, while markedly reducing 13C-acetate labeling of dihydroorotate and orotate, intermediates in de novo pyrimidine synthesis. Untargeted metabolomics reveal enrichment of pyrimidine biosynthesis pathways in ACSS1-high cells. Notably, acetate or uridine supplementation rescues the growth of ACSS1-deficient cells, confirming a functional link between acetate metabolism and nucleotide synthesis. Importantly, in vivo studies using luciferase-labeled JeKo-1 and Maver mantle cell lymphoma xenografts demonstrate that ACSS1 knockdown significantly suppresses tumor growth. NSG mice injected with ACSS1-silenced cells exhibit a marked reduction in tumor burden, as measured by bioluminescence imaging and total photon flux, with significant differences observed at days 14 and 21 post-injection. These findings establish that ACSS1 is required not only for metabolic adaptation in vitro but also for lymphoma progression in vivo. Collectively, our results uncover an ACSS1-dependent mitochondrial acetate-pyrimidine axis that sustains lymphoma growth and represents a previously unrecognized therapeutic vulnerability. Statement of SignificanceThis study identifies ACSS1 as a critical metabolic vulnerability in mantle cell lymphoma (MCL), linking mitochondrial acetate metabolism to de novo pyrimidine biosynthesis and tumor progression. We demonstrate that ACSS1 is frequently overexpressed in MCL and is essential for converting acetate into mitochondrial acetyl-CoA, thereby sustaining TCA cycle activity, nucleotide production, and cell survival under nutrient stress. Loss of ACSS1 disrupts this acetate-pyrimidine axis, impairing oxidative metabolism and reducing lymphoma cell viability in vitro. Importantly, ACSS1 silencing significantly suppresses tumor growth in vivo, establishing its requirement for lymphoma progression. The ability of acetate or uridine supplementation to rescue ACSS1-deficient cells further highlights the functional coupling between mitochondrial acetate utilization and nucleotide synthesis. Together, these findings reveal a previously unrecognized mechanism of metabolic adaptation in aggressive lymphomas and offer ACSS1-mediated acetate metabolism as a promising therapeutic target.

cancer biology↗

bioRxiv2024

Mitochondrial ACSS1 regulates the oncometabolite 2-hydroxyglutarate and De Novo Pyrimidine biosynthesis under nutrient-deprived conditions in lymphoma

The mitochondrial Acetyl-CoA synthetase short-chain family member 1 (ACSS1) converts acetate, an energy source in nutrient-deprived conditions, to mitochondrial acetyl-CoA. However, the specific mechanism behind this process remains unknown. Here, we show that ACSS1 is overexpressed in patients with mantle cell lymphoma (MCL), diffuse large B cell lymphoma (DLBCL), chronic lymphocytic leukemia (CLL), and Ibrutinib (IBR)-resistant cell lines. The mitochondrial stress test showed reduced oxygen consumption in ACSS1 knockdown (KD) cell lines. 13C-acetate stable isotope tracing revealed that ACSS1 knockdown (KD) in MCL cell lines attenuates the flux of mitochondrial acetate to acetyl-CoA, acetylcarnitine, and TCA cycle intermediates, including glutamine and aspartate, which are precursors for de novo pyrimidine synthesis. Consistently, there was a decrease in the labeling of glutamate, aspartate, dihydroorotate, and orotate pools in KD cell lines. Pathway analysis revealed the enrichment of de novo pyrimidine synthesis metabolites and depleting ACSS1 impaired cell growth and potential vulnerability of IBR-resistant MCL cells. Further, we discovered that acetate is used to synthesize 2-hydroxyglutarate in an ACSS1-dependent manner, and it is involved in histone methylation. These results highlight a metabolic phenotype in MCL cells, showing their ability to metabolize acetate in nutrient-deprived conditions and provide new insights into the role of ACSS1 in cancer metabolism. SignificanceThe enzyme ACSS1 catalyzes the conversion of acetate, an energy source in nutrient-deprived conditions, to mitochondrial acetyl-CoA. Our results show that ACSS1 may affect cancer metabolism, particularly in MCL. Studies using MCL cell lines showed that reducing ACSS1 activity affects acetate utilization for various metabolic pathways and influences the production of oncometabolite D-2-hydroxyglutarate. Additionally, reducing ACSS1 activity affects the expression of cyclin D1 and inhibits cell growth, highlighting the potential significance of ACSS1 in cancer metabolism.

cancer biology↗

bioRxiv2023

Therapeutic targeting of ACLY in T-ALL in vivo

T-cell Acute Lymphoblastic Leukemia (T-ALL) is a hematological malignancy in need of novel therapeutic approaches. Here, we identify the ATP-citrate lyase ACLY as overexpressed and as a novel therapeutic target in T-ALL. To test the effects of ACLY in leukemia progression, we developed an isogenic model of NOTCH1-induced Acly conditional knockout leukemia. Importantly, we observed intrinsic antileukemic effects upon loss of ACLY, which further synergized with NOTCH1 inhibition in vivo. Metabolomic profiling upon ACLY loss revealed a metabolic crisis with reduced acetyl-CoA levels, as well as a decreased oxygen consumption rate. Gene expression profiling analyses showed that the transcriptional signature of ACLY loss very significantly correlates with the signature of MYC loss in vivo. Mechanistically, the decrease in acetyl-CoA led to reduced H3K27ac levels in Myc, resulting in transcriptional downregulation of Myc and drastically reduced MYC protein levels. Interestingly, our analyses also revealed a reciprocal relationship whereby ACLY itself is a direct transcriptional target of MYC, thus establishing a feedforward loop that is important for leukemia progression. Overall, our results identified a relevant ACLY-MYC axis and unveiled ACLY as a novel promising target for T-ALL treatment.

cancer biology↗

bioRxiv2023

ATP citrate lyase is an essential player of the metabolic rewiring induced by PTEN loss during T-ALL development.

Alterations inactivating the tumor suppressor gene PTEN drive the development of solid and hematological cancers, such as T-cell acute lymphoblastic leukemia (T-ALL), whereby PTEN loss defines poor-prognosis patients. We investigated the metabolic rewiring induced by PTEN loss in T-ALL, aiming at identifying novel metabolic vulnerabilities. We showed that the enzyme ATP citrate lyase (ACLY) is strictly required for the transformation of thymic immature progenitors and for the growth of human T-ALL, which remain dependent on ACLY activity even upon transformation. Whereas PTEN mutant mice all died within 17 weeks, the concomitant ACLY deletion prevented disease initiation in 70% of the animals, where it prevented the apoptosis of pre-malignant DP thymocytes by up-regulating BCL-2. Transcriptomic and metabolic analysis of primary T-ALL cells next translated our findings to the human pathology, showing that PTEN-altered T-ALL cells selectively activate ACLY and are specifically sensitive to its genetic targeting. ACLY activation thus represents a metabolic vulnerability with therapeutic potential for high-risk T-ALL patients.

cancer biology↗

bioRxiv2020

Quantitative prospective and retrospective mass spectrometry of lactoyl-CoA in mammalian cells and tissues

Lysine lactoylation is a recently described protein post-translational modification (PTM). However, the biochemical pathways responsible for this acylation remain unclear. Two metabolite-dependent mechanisms have been proposed: enzymatic histone lysine lactoylation derived from lactoyl-coenzyme A (lactoyl-CoA, also termed lactyl-CoA), and non-enzymatic lysine lactoylation resulting from acyl-transfer via lactoyl-glutathione. While the former has precedent in the form of enzyme-catalyzed lysine acylation, the lactoyl-CoA metabolite has not been previously quantified in mammalian systems. Here we use liquid chromatography-high resolution mass spectrometry (LC-HRMS) together with a synthetic standard to detect and validate the presence of lactoyl-CoA in cell and tissue samples. Conducting a retrospective analysis of data from previously analyzed samples revealed the presence of lactoyl-CoA in diverse cell and tissue contexts. In addition, we describe a biosynthetic route to generate 13C3 15N1 -isotopically-labeled lactoyl-CoA, providing a co-eluting internal standard for analysis of this metabolite. We estimate lactoyl-CoA concentrations of 1.14x10-8 pmol/cell in cell culture and 0.0172 pmol/mg tissue wet weight in mouse heart. These levels are similar to crotonyl-CoA, but between 20-350 times lower than predominant acyl-CoAs such as acetyl-, propionyl-, and succinyl-CoA. Overall our studies provide the first quantitative measurements of lactoyl-CoA and provide a methodological foundation for the interrogation of this novel metabolite in biology and disease. Highlights- Detection of lactoyl-CoA at picomole concentrations across tissues and cells - Lactoyl-CoA was detected at concentrations similar to crontonyl-CoA within HepG2 cells - Isotopically labeled 13C315N1-lactoyl-CoA can be prepared by SILEC

biochemistry↗

bioRxiv2020

Tyrosine phosphorylation of ACLY regulates lipid metabolism and oncogenesis in ALK positive Anaplastic Large Cell Lymphoma

A fundamental requirement for growth of rapidly proliferating cells is metabolic adaptation to promote synthesis of biomass1. ATP citrate lyase (ACLY) is a critical enzyme responsible for synthesis of cytosolic acetyl-CoA, the key building component for de novo fatty acid synthesis and links vital pathways such as carbohydrate and lipid metabolism2. The mechanisms of ACLY regulation are not completely understood and the regulation of ACLY function by tyrosine phosphorylation is unknown. Here we show using mass-spectrometry-driven phosphoproteomics and metabolomics that ACLY is phosphorylated and functionally regulated at an evolutionary conserved residue, Y682. Physiologic signals promoting rapid cell growth such as epidermal growth factor stimulation in epithelial cells and T-cell receptor activation in primary human T-cells result in rapid phosphorylation of ACLY at Y682. In vitro kinase assays demonstrate that Y682 is directly phosphorylated by multiple tyrosine kinases, including ALK, ROS1, SRC, JAK2 and LTK. Oncogenically activating structural alterations such as gene-fusions, amplification or point mutations of ALK tyrosine kinase result in constitutive phosphorylation of ACLY in diverse forms of primary human cancer such as lung cancer, anaplastic large cell lymphoma (ALCL) and neuroblastoma. Expression of a phosphorylation-defective ACLY-Y682F mutant in NPM-ALK+ ALCL decreases ACLY activity and attenuates lipid synthesis. Metabolomic analyses reveal that ACLY-Y682F expression results in increased {beta}-oxidation of 13C-oleic acid-labeled fatty acid with increased labeling of +2-citrate (p<0.01) and +18-oleyol carnitine (p<0.001). Similarly, oxygen consumption rate (OCR) is significantly increased in cells expressing ACLY-Y682F (p<0.001). Moreover, expression of ACLY-Y682F dramatically decreases cell proliferation, impairs clonogenicity and abrogates tumor growth in vivo. Our results reveal a novel mechanism for direct ACLY regulation that is subverted by multiple oncogenically-activated tyrosine kinases in diverse human cancers. These findings have significant implications for novel therapies targeting ACLY in cancer and metabolism.

cancer biology↗