title: Exo-MFA - A 13C metabolic flux analysis framework to dissect tumor microenvironment-secreted exosome contributions towards cancer cell metabolism.
abstract: Dissecting the pleiotropic roles of tumor micro-environment (TME) on cancer progression has been brought to the foreground of research on cancer pathology. Extracellular vesicles such as exosomes, transport proteins, lipids, and nucleic acids, to mediate intercellular communication between TME components and have emerged as candidates for anti-cancer therapy. We previously reported that cancer-associated fibroblast (CAF) derived exosomes (CDEs) contain metabolites in their cargo that are utilized by cancer cells for central carbon metabolism and promote cancer growth. However, the metabolic fluxes involved in donor cells towards packaging of metabolites in extracellular vesicles and exosome-mediated metabolite flux upregulation in recipient cells are still not known. Here, we have developed a novel empirical and computational technique, exosome-mediated metabolic flux analysis (Exo-MFA) to quantify flow of cargo from source cells to recipient cells via vesicular transport. Our algorithm, which is based on13C metabolic flux analysis, successfully predicts packaging fluxes to metabolite cargo in CAFs, dynamic changes in rate of exosome internalization by cancer cells, and flux of cargo release over time. We find that cancer cells internalize exosomes rapidly leading to depletion of extracellular exosomes within 24h. However, metabolite cargo significantly alters intracellular metabolism over the course of 24h by regulating glycolysis pathway fluxes via lactate supply. Furthermore, it can supply up to 35% of the TCA cycle fluxes by providing TCA intermediates and glutamine. Our algorithm will help gain insight into (i) metabolic interactions in multicellular systems (ii) biogenesis of extracellular vesicles and their differential packaging of cargo under changing environments, and (iii) regulation of cancer cell metabolism by its microenvironment.
authors.affiliation: Laboratory for Systems Biology of Human Diseases, Rice University, Houston, TX 77005, USA; Department of Chemical and Biomolecular Engineering, Rice University, Houston, TX 77005, USA; Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI 48109, USA.
authors.forename: Abhinav
authors.initials: A
authors.lastname: Achreja
authors.affiliation: Laboratory for Systems Biology of Human Diseases, Rice University, Houston, TX 77005, USA; Department of Chemical and Biomolecular Engineering, Rice University, Houston, TX 77005, USA; Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI 48109, USA.
authors.forename: Hongyun
authors.initials: H
authors.lastname: Zhao
authors.affiliation: Laboratory for Systems Biology of Human Diseases, Rice University, Houston, TX 77005, USA; Department of Chemical and Biomolecular Engineering, Rice University, Houston, TX 77005, USA.
authors.forename: Lifeng
authors.initials: L
authors.lastname: Yang
authors.affiliation: Department of Chemical and Biomolecular Engineering, Rice University, Houston, TX 77005, USA.
authors.forename: Tae Hyun
authors.initials: TH
authors.lastname: Yun
authors.affiliation: Baylor College of Medicine, TX 77005, USA.
authors.forename: Juan
authors.initials: J
authors.lastname: Marini
authors.affiliation: Laboratory for Systems Biology of Human Diseases, Rice University, Houston, TX 77005, USA; Department of Chemical and Biomolecular Engineering, Rice University, Houston, TX 77005, USA; Department of Bioengineering, Rice University, Houston, TX 77005, USA; Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI 48109, USA; Biointerfaces Institute, University of Michigan, Ann Arbor, MI 48109, USA. Electronic address: dnagrath@umich.edu.
authors.forename: Deepak
authors.initials: D
authors.lastname: Nagrath
mesh_terms: D002247:Carbon Isotopes / Q000737:chemistry*; D002450:Cell Communication; D045744:Cell Line, Tumor; D002952:Citric Acid Cycle; D055354:Exosomes / Q000378:metabolism*; D006019:Glycolysis; D006801:Humans; D007553:Isotope Labeling; D009369:Neoplasms / Q000378:metabolism* / Q000473:pathology; D059016:Tumor Microenvironment
chemical_list: D002247:Carbon Isotopes
keywords: 13C-metabolic flux analysis; Cancer metabolism; Exo-MFA; Exosomes; Intercellular metabolic flux analysis; Tumor microenvironment