Causes and Consequences of A Glutamine Induced Normoxic HIF1 Activity for the Tumor Metabolism

International Journal of Molecular Sciences

Helge Taubert¹  Martin Porsch²  Fabian Bull²  Knut Krohn³  Matthias Kappler⁴  Tom Kaune⁴  Johanna Kotrba⁴  Swetlana Rot⁴  AlexanderW. Eckert⁴  Ulrike Pabst⁴  Johannes Schubert⁴  Bilal Al-Nawas⁴  Antje Güttler⁵  Dirk Vordermark⁵  Matthias Bache⁵  Claus Weinholdt⁶  Ivo Grosse⁶  Barbara Seliger⁷  Claudia Wickenhauser⁸  Oliver Thews⁹  Anne Riemann⁹ 

[1] Clinic of Urology and Pediatric Urology, FA University Hospital Erlangen-Nürnberg, 91054 Erlangen, Germany;Core Facility Deep Sequencing, Institute of Computer Science, and Institute of Human Genetics, Martin Luther University Halle-Wittenberg, 06120 Halle (Saale), Germany;Core Unit DNA Technologies, University of Leipzig, 04103 Leipzig, Germany;Department of Oral and Maxillofacial Plastic Surgery, Martin Luther University Halle-Wittenberg, 06120 Halle (Saale), Germany;Department of Radiotherapy, Martin Luther University Halle-Wittenberg, 06120 Halle (Saale), Germany;Institute of Computer Science, Martin Luther University Halle-Wittenberg, 06120 Halle (Saale), Germany;Institute of Medical Immunology, Martin-Luther-University Halle-Wittenberg, 06110 Halle (Saale), Germany;Institute of Pathology, Martin-Luther-University Halle-Wittenberg, 06110 Halle (Saale), Germany;Institute of Physiology, Martin Luther University Halle-Wittenberg, 06110 Halle (Saale), Germany;

关键词: HIF1α;    hypoxia;    normoxia;    glutamine;    glutaminolysis;    glycolysis;    Warburg effect;    metabolism;    tumor;    L-ascorbic acid;    acetylsalicylic acid;   

DOI  :  10.3390/ijms20194742

来源: DOAJ

【 摘 要 】

The transcription factor hypoxia-inducible factor 1 (HIF1) is the crucial regulator of genes that are involved in metabolism under hypoxic conditions, but information regarding the transcriptional activity of HIF1 in normoxic metabolism is limited. Different tumor cells were treated under normoxic and hypoxic conditions with various drugs that affect cellular metabolism. HIF1α was silenced by siRNA in normoxic/hypoxic tumor cells, before RNA sequencing and bioinformatics analyses were performed while using the breast cancer cell line MDA-MB-231 as a model. Differentially expressed genes were further analyzed and validated by qPCR, while the activity of the metabolites was determined by enzyme assays. Under normoxic conditions, HIF1 activity was significantly increased by (i) glutamine metabolism, which was associated with the release of ammonium, and it was decreased by (ii) acetylation via acetyl CoA synthetase (ACSS2) or ATP citrate lyase (ACLY), respectively, and (iii) the presence of L-ascorbic acid, citrate, or acetyl-CoA. Interestingly, acetylsalicylic acid, ibuprofen, L-ascorbic acid, and citrate each significantly destabilized HIF1α only under normoxia. The results from the deep sequence analyses indicated that, in HIF1-siRNA silenced MDA-MB-231 cells, 231 genes under normoxia and 1384 genes under hypoxia were transcriptionally significant deregulated in a HIF1-dependent manner. Focusing on glycolysis genes, it was confirmed that HIF1 significantly regulated six normoxic and 16 hypoxic glycolysis-associated gene transcripts. However, the results from the targeted metabolome analyses revealed that HIF1 activity affected neither the consumption of glucose nor the release of ammonium or lactate; however, it significantly inhibited the release of the amino acid alanine. This study comprehensively investigated, for the first time, how normoxic HIF1 is stabilized, and it analyzed the possible function of normoxic HIF1 in the transcriptome and metabolic processes of tumor cells in a breast cancer cell model. Furthermore, these data imply that HIF1 compensates for the metabolic outcomes of glutaminolysis and, subsequently, the Warburg effect might be a direct consequence of the altered amino acid metabolism in tumor cells.

【 授权许可】

Unknown