ACLY and ACC1 Regulate Hypoxia-Induced Apoptosis by Modulating ETV4 via α-ketoglutarate.

Abstract

In order to propagate a solid tumor, cancer cells must adapt to and survive under various tumor microenvironment (TME) stresses, such as hypoxia or lactic acidosis. To systematically identify genes that modulate cancer cell survival under stresses, we performed genome-wide shRNA screens under hypoxia or lactic acidosis. We discovered that genetic depletion of acetyl-CoA carboxylase (ACACA or ACC1) or ATP citrate lyase (ACLY) protected cancer cells from hypoxia-induced apoptosis. Additionally, the loss of ACLY or ACC1 reduced levels and activities of the oncogenic transcription factor ETV4. Silencing ETV4 also protected cells from hypoxia-induced apoptosis and led to remarkably similar transcriptional responses as with silenced ACLY or ACC1, including an anti-apoptotic program. Metabolomic analysis found that while α-ketoglutarate levels decrease under hypoxia in control cells, α-ketoglutarate is paradoxically increased under hypoxia when ACC1 or ACLY are depleted. Supplementation with α-ketoglutarate rescued the hypoxia-induced apoptosis and recapitulated the decreased expression and activity of ETV4, likely via an epigenetic mechanism. Therefore, ACC1 and ACLY regulate the levels of ETV4 under hypoxia via increased α-ketoglutarate. These results reveal that the ACC1/ACLY-α-ketoglutarate-ETV4 axis is a novel means by which metabolic states regulate transcriptional output for life vs. death decisions under hypoxia. Since many lipogenic inhibitors are under investigation as cancer therapeutics, our findings suggest that the use of these inhibitors will need to be carefully considered with respect to oncogenic drivers, tumor hypoxia, progression and dormancy. More broadly, our screen provides a framework for studying additional tumor cell stress-adaption mechanisms in the future.

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Citation

Published Version (Please cite this version)

10.1371/journal.pgen.1005599

Publication Info

Keenan, Melissa M, Beiyu Liu, Xiaohu Tang, Jianli Wu, Derek Cyr, Robert D Stevens, Olga Ilkayeva, Zhiqing Huang, et al. (2015). ACLY and ACC1 Regulate Hypoxia-Induced Apoptosis by Modulating ETV4 via α-ketoglutarate. PLoS Genet, 11(10). p. e1005599. 10.1371/journal.pgen.1005599 Retrieved from https://hdl.handle.net/10161/13614.

This is constructed from limited available data and may be imprecise. To cite this article, please review & use the official citation provided by the journal.

Scholars@Duke

Stevens

Robert David Stevens

Adjunct Assistant Professor of Medicine
Ilkayeva

Olga Ilkayeva

Assistant Professor in Medicine

Olga Ilkayeva, Ph.D., is the Director of the Metabolomics Core Laboratory at Duke Molecular Physiology Institute. She received her Ph.D. training in Cell Regulation from UT Southwestern Medical Center at Dallas, TX. Her postdoctoral research in the laboratory of Dr. Chris Newgard at Duke University Medical Center focused on lipid metabolism and regulation of insulin secretion. As a research scientist at the Stedman Nutrition and Metabolism Center, Dr. Ilkayeva expanded her studies to include the development of targeted mass spectrometry analyses. Currently, she works on developing and validating quantitative mass spectrometry methods used for metabolic profiling of various biological models with emphasis on diabetes, obesity, cardiovascular disease, and the role of gut microbiome in both health and disease.

Huang

Zhiqing Huang

Assistant Professor in Obstetrics and Gynecology

Dr. Huang is an Assistant Professor in the Department of Obstetrics and Gynecology, Division of Reproductive Sciences, at Duke University Medical Center. She obtained her MD at North China Coal Medical University in China and her PhD at the University of Heidelberg in Germany under the mentorship of Dr. Ralph Witzgall. She did her postdoctoral training with Dr. Jiemin Wong at Baylor College of Medicine, studying how histone methylation and chromatin modifications regulate androgen receptor transcription. 

Dr. Huang’s research includes the following:

•The factors in the tumor microenvironment contribute to ovarian cancer progress;
•New drug development for recurrent ovarian cancer treatment;
•The early DNA methylation profiles contribute to cancer development in late life;
•The special changes in the tumor microenvironment;
•Epigenetics and epigenomics.
*The impact of lipid metabolism in the tumor microenvironment in cancer progression and treatment.
*Impact of ferroptosis in endometriosis development. 

Dr. Huang has received an R03 funding titled “Role of Age-Related Changes in the Tumor Microenvironment on Ovarian Cancer Progression” from NIA at NIH for 2021-2023.
Dr. Huang received Charles B. Hammond's Research Fund from the Department of Obstetrics and Gynecology at Duke University in November 2022, for a project titled "Single Cell Spatial Transcriptomics in Highly Aggressive and Less Aggressive Ovarian Cancer".
Dr. Huang has received Duke Cancer Institute 2023 spring pilot study award for07012023-06302024, the project title is "Age Effects on Chemotherapy Targeting Cells Causing Ovarian Cancer Recurrence”.
Dr. Huang has received the American Cancer Society -Duke Cancer Institute (ASC-DCI) 2024 spring pilot study award for 07012024-06302025. The project title is "Early Establishment of Epigenetic Profiles that Increase Cancer Risk in Late Life”.
Dr. Huang received Charles B. Hammond's Research Fund from the Department of Obstetrics and Gynecology at Duke University in November 2023 for 01012024-12312024. The project's title is "Age Effects on Chemotherapy Targeting Cells Causing Ovarian Cancer Recurrence".

Muoio

Deborah Marie Muoio

George Barth Geller Distinguished Professor of Cardiovascular Disease

Deb Muoio is professor in the Departments of Medicine and Pharmacology & Cancer Biology, George Barth Geller Distinguished Professor of Cardiovascular Disease, and Associate Director of the Duke Molecular Physiology Institute (DMPI). She is viewed nationally and internationally as a leader in the fields of diabetes, obesity, exercise physiology, and mitochondrial energy metabolism. Her laboratory investigates mechanisms of metabolic regulation, with emphasis on molecular events that link lifestyle factors such as over nutrition and physical inactivity to metabolic disorders, including obesity, diabetes, and heart failure. Her program features a translational approach that combines work in animal and cell-based models with human studies, using genetic engineering, molecular biology and mass spectrometry-based metabolomics and proteomics as tools to understand the interplay between mitochondrial physiology and cardiometabolic health. Her laboratory developed a sophisticated platform for deep and comprehensive assessment of mitochondrial bioenergetics and energy transduction. Her team is integrating this new platform with metabolomics, proteomics, and metabolic flux analysis to gain insights into mechanisms by which mitochondria modulate insulin action and metabolic resilience. She has published more than 120 papers in prominent journals such as Cell, Cell Metabolism, Circulation, Circulation Research, Diabetes, and JCI Insight. Dr. Muoio’s laboratory has enjoyed longstanding support from the NIDDK and NHLBI.

PhD, University of North Carolina, Chapel Hill, NC

Kim

So Young Kim

Associate Research Professor in Molecular Genetics and Microbiology

I serve as Director of the Duke Functional Genomics Core Facility, where our central mission is to provide resources for high-throughput analysis of gene function and small molecule screens for drug discovery. Our core works with Duke investigators to provide the expertise, infrastructure and libraries necessary for these screens and can collaborate on all stages of the screening project, including study design, assay optimization and data analysis. The facility also provides services for custom cell line engineering using techniques including CRISPR knockouts/knockins, RNAi gene suppression and ORF expression. Our lab is also interested in collaborating with investigators to develop and improve existing methodologies to enhance the utility of functional genomics tools within the lab. 

I am also the Director of the Duke Microbiome Core Facility, which supports the research of investigators seeking to uncover the roles that microbiomes play in human health and the environment. The core provides assistance with study design, sample management, DNA extractions, NGS library prep and data analysis. The lab is also interested in developing new techniques and analysis tools to better assess microbiome composition across a range of sample types.

Chi

Jen-Tsan Ashley Chi

Professor in Molecular Genetics and Microbiology

We are using functional genomic approaches to investigate the nutrient signaling and stress adaptations of cancer cells when exposed to various nutrient deprivations and microenvironmental stress conditions. Recently, we focus on two areas. First, we are elucidating the genetic determinants and disease relevance of ferroptosis, a newly recognized form of cell death. Second, we have identified the mammalian stringent response pathway which is highly similar to bacterial stringent response, but with some very interesting twists and novel mechanisms.

A. The genetic determinants and disease relevance of ferroptosis

Ferroptosis is a newly recognized form of cell death that is characterized by iron dependency and lipid peroxidation. The importance of ferroptosis is being recognized in many human diseases, including cancers, ischemia injuries, and neurodegeneration. Previously, we have identified the profound cystine addiction of renal cell carcinoma (1), breast cancer cells (2, 3), and ovarian cancer cells (4). Based on the concept that cystine deprivation triggers the ferroptosis due to the unopposed oxidative stresses, we have performed functional genomic screens to identify many novel genetic determinants of ferroptosis. For example, we have found that DNA damage response and ATM kinase regulate ferroptosis via affecting iron metabolism (5). This finding supports the potential of ionizing radiation to trigger DNA damage response and synergize with ferroptosis to treat human cancers. In addition, we found that ferroptosis is highly regulated by cell density. When cells are grown at low density, they are highly susceptible to ferroptosis. In contrast, the same cells become resistant to ferroptosis when grown at high density and confluency. we have found the Hippo pathway effectors TAZ and YAP are responsible for the cell density-dependent ferroptosis (4, 6, 7). Right now, we are pursuing several other novel determinants of ferroptosis that will reveal surprising insights into this new form of cell death.

B. A new stress pathway – mammalian stress response

All living organisms encounter a wide variety of nutrient deprivations and environmental stresses. Therefore, all organisms have developed various mechanisms to respond and promote survival under stress. In bacteria, the main strategy is “stringent response” triggered by the accumulation of the alarmone (p)ppGpp (shortened to ppGpp below) via regulation of its synthetase RelA and its hydrolase SpoT (8). The ppGpp binds to the transcription factor DksA and RNA polymerase to orchestrate extensive transcriptional changes that repress proliferation and promote stress survival (8, 9). While highly conserved among bacteria, the stringent response had not been reported in metazoans. However, a recent study identified Drosophila and human MESH1 (Metazoan SpoT Homolog 1) as the homologs of the ppGpp hydrolase domain of the bacterial SpoT (10). Both MESH1 proteins exhibit ppGpp hydrolase activity, and the deletion of Mesh1 in Drosophila led to a transcriptional response reminiscent of the bacterial stringent response (10). Recently, we have found that the genetic removal of MESH1 in tumor cells triggers extensive transcriptional changes and confers protection against oxidative stress-induced ferroptosis (11). Importantly, MESH1 removal also triggers proliferative arrest and other robust anti-tumor effects. Therefore, MESH1 knockdown leads to both stress survival and proliferation arrest, two cardinal features highly reminiscent of the bacterial stringent response. Therefore, we termed this pathway as “mammalian stringent response” (12). We have found that NADPH is the relevant MESH1 in the contexts of ferroptosis (13). Now, we are investigating how MESH1 removal leads to proliferation of arrests and anti-tumor phenotypes. Furthermore, we have found several other substrates of MESH1. We are investigating their function using culture cells, MESH1 KO mice, and other model organisms.

 

C. Genomic and single cell RNA analysis of Red Blood Cells

Red blood cells (RBC) are responsible for oxygen delivery to muscles during vigorous exercise. Therefore, many doping efforts focus on increasing RBC number and function to boost athletic performance during competition. For many decades, RBC were thought to be merely identical “sacs of hemoglobin” with no discernable differences due to factors such as age or pre-transfusion storage time. Additionally, because RBC lose their nuclei during terminal differentiation, they were not believed to retain any genetic materials.  These long-held beliefs have now been disproven and the results have significant implications for detecting autologous blood transfusion (ABT) doping in athletes.  We were among the first to discover that RBCs contain abundant and diverse species of RNAs. Using this knowledge, we subsequently optimized protocols and performed genomic analysis of the RBC transcriptome in sickle cell disease; these results revealed that heterogeneous RBCs could be divided into several subpopulations, which had implications for the mechanisms of malaria resistance. As an extension of these studies, we used high resolution Illumina RNA-Seq approaches to identify hundreds of additional known and novel microRNAs, mRNAs, and other RNA species in RBCs. This dynamic RBC transcriptome represents a significant opportunity to assess the impact that environmental factors (such as pre-transfusion refrigerate storage) on the RBC transcriptome. We have now identified a >10-fold change in miR-720 as well as several other RNA transcripts whose levels are significantly altered by RBC storage (14) which gained significant press coverage. We are pursuing the genomic and single cell analysis of RNA transcriptome in the context of blood doping, sickle cell diseases and other red cell diseases.

 

 

 

 

1.         Tang X, Wu J, Ding CK, Lu M, Keenan MM, Lin CC, et al. Cystine Deprivation Triggers Programmed Necrosis in VHL-Deficient Renal Cell Carcinomas. Cancer Res. 2016;76(7):1892-903.

2.         Tang X, Ding CK, Wu J, Sjol J, Wardell S, Spasojevic I, et al. Cystine addiction of triple-negative breast cancer associated with EMT augmented death signaling. Oncogene. 2017;36(30):4379.

3.         Lin CC, Mabe NW, Lin YT, Yang WH, Tang X, Hong L, et al. RIPK3 upregulation confers robust proliferation and collateral cystine-dependence on breast cancer recurrence. Cell Death Differ. 2020.

4.         Yang WH, Huang Z, Wu J, Ding C-KC, Murphy SK, Chi J-T. A TAZ-ANGPTL4-NOX2 axis regulates ferroptotic cell death and chemoresistance in epithelial ovarian cancer. Molecular Cancer Research. 2019: molcanres.0691.2019.

5.         Chen PH, Wu J, Ding CC, Lin CC, Pan S, Bossa N, et al. Kinome screen of ferroptosis reveals a novel role of ATM in regulating iron metabolism. Cell Death Differ. 2019.

6.         Yang W-H, Chi J-T. Hippo pathway effectors YAP/TAZ as novel determinants of ferroptosis. Molecular & Cellular Oncology. 2019:1699375.

7.         Yang WH, Ding CKC, Sun T, Hsu DS, Chi JT. The Hippo Pathway Effector TAZ Regulates Ferroptosis in Renal Cell Carcinoma Cell Reports. 2019;28(10):2501-8.e4.

8.         Potrykus K, Cashel M. (p)ppGpp: still magical? Annu Rev Microbiol. 2008;62:35-51.

9.         Kriel A, Bittner AN, Kim SH, Liu K, Tehranchi AK, Zou WY, et al. Direct regulation of GTP homeostasis by (p)ppGpp: a critical component of viability and stress resistance. Mol Cell. 2012;48(2):231-41.

10.       Sun D, Lee G, Lee JH, Kim HY, Rhee HW, Park SY, et al. A metazoan ortholog of SpoT hydrolyzes ppGpp and functions in starvation responses. Nat Struct Mol Biol. 2010;17(10):1188-94.

11.       Dixon SJ, Lemberg KM, Lamprecht MR, Skouta R, Zaitsev EM, Gleason CE, et al. Ferroptosis: an iron-dependent form of nonapoptotic cell death. Cell. 2012;149(5):1060-72.

12.       Ding C-KC, Rose J, Wu J, Sun T, Chen K-Y, Chen P-H, et al. Mammalian stringent-like response mediated by the cytosolic NADPH phosphatase MESH1. bioRxiv. 2018.

13.       Ding C-KC, Rose J, Sun T, Wu J, Chen P-H, Lin C-C, et al. MESH1 is a cytosolic NADPH phosphatase that regulates ferroptosis. Nature Metabolism. 2020.

14.       Yang WH, Doss JF, Walzer KA, McNulty SM, Wu J, Roback JD, et al. Angiogenin-mediated tRNA cleavage as a novel feature of stored red blood cells. Br J Haematol. 2018.

 

 


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