bims-stacyt 2022-10-02 papers

Proc Natl Acad Sci U S A. 2022 Oct 04. 119(40): e2122382119

Autocrine FGF1 signaling promotes glucose uptake in adipocytes.

Vera J M Nies, Dicky Struik, Sihao Liu, Weilin Liu, Janine K Kruit, Michael Downes, Tim van Zutphen, Henkjan J Verkade, Ronald M Evans, Johan W Jonker.

Fibroblast growth factor 1 (FGF1) is an autocrine growth factor released from adipose tissue during over-nutrition or fasting to feeding transition. While local actions underlie the majority of FGF1's anti-diabetic functions, the molecular mechanisms downstream of adipose FGF receptor signaling are unclear. We investigated the effects of FGF1 on glucose uptake and its underlying mechanism in murine 3T3-L1 adipocytes and in ex vivo adipose explants from mice. FGF1 increased glucose uptake in 3T3-L1 adipocytes and epididymal WAT (eWAT) and inguinal WAT (iWAT). Conversely, glucose uptake was reduced in eWAT and iWAT of FGF1 knockout mice. We show that FGF1 acutely increased adipocyte glucose uptake via activation of the insulin-sensitive glucose transporter GLUT4, involving dynamic crosstalk between the MEK1/2 and Akt signaling proteins. Prolonged exposure to FGF1 stimulated adipocyte glucose uptake by MEK1/2-dependent transcription of the basal glucose transporter GLUT1. We have thus identified an alternative pathway to stimulate glucose uptake in adipocytes, independent from insulin, which could open new avenues for treating patients with type 2 diabetes.

Keywords: FGF1; adipocytes; fibroblast growth factors; glucose metabolism; insulin

DOI: https://doi.org/10.1073/pnas.2122382119

Cancer Drug Resist. 2022 ;5(3): 577-594

Exosome secretion from hypoxic cancer cells reshapes the tumor microenvironment and mediates drug resistance.

Kenneth K W To, William C S Cho.

Hypoxia is a common phenomenon in solid tumors as the poorly organized tumor vasculature cannot fulfill the increasing oxygen demand of rapidly expanding tumors. Under hypoxia, tumor cells reshape their microenvironment to sustain survival, promote metastasis, and develop resistance to therapy. Exosomes are extracellular vesicles secreted by most eukaryotic cells, including tumor cells. They are enriched with a selective collection of nucleic acids and proteins from the originating cells to mediate cell-to-cell communication. Accumulating evidence suggests that exosomes derived from tumor cells play critical roles in modulating the tumor microenvironment (TME). Hypoxia is known to stimulate the secretion of exosomes from tumor cells, thereby promoting intercellular communication of hypoxic tumors with the surrounding stromal tissues. Exosome-mediated signaling pathways under hypoxic conditions have been reported to cause angiogenesis, invasion, metastasis, drug resistance, and immune escape. Recently, the programmed cell death ligand-1 (PD-L1) has been reported to reside as a transmembrane protein in tumor exosomes. Exosomal PD-L1 was shown to suppress T cell effector function in the TME and cause drug resistance to immune checkpoint therapy. This review provides an update about the pivotal role of tumor-derived exosomes in drug resistance to chemotherapy and immunotherapy, particularly under hypoxic conditions. Emerging strategies that target the exosomes in the hypoxic TME to enhance the antitumor efficacy are discussed.

Keywords: Hypoxia; drug resistance; exosome; immunotherapy; non-coding RNA; tumor microenvironment

DOI: https://doi.org/10.20517/cdr.2022.38

Science. 2022 Sep 30. 377(6614): 1519-1529

Oncometabolite d-2HG alters T cell metabolism to impair CD8+ T cell function.

Gain-of-function mutations in isocitrate dehydrogenase (IDH) in human cancers result in the production of d-2-hydroxyglutarate (d-2HG), an oncometabolite that promotes tumorigenesis through epigenetic alterations. The cancer cell-intrinsic effects of d-2HG are well understood, but its tumor cell-nonautonomous roles remain poorly explored. We compared the oncometabolite d-2HG with its enantiomer, l-2HG, and found that tumor-derived d-2HG was taken up by CD8+ T cells and altered their metabolism and antitumor functions in an acute and reversible fashion. We identified the glycolytic enzyme lactate dehydrogenase (LDH) as a molecular target of d-2HG. d-2HG and inhibition of LDH drive a metabolic program and immune CD8+ T cell signature marked by decreased cytotoxicity and impaired interferon-γ signaling that was recapitulated in clinical samples from human patients with IDH1 mutant gliomas.

DOI: https://doi.org/10.1126/science.abj5104

Metabolomics. 2022 Sep 30. 18(10): 76

Glutathione, polyamine, and lysophosphatidylcholine synthesis pathways are associated with circulating pro-inflammatory cytokines.

Ming Liu, Hongwei Zhang, Zikun Xie, Yiheng Huang, Guang Sun, Dake Qi, Andrew Furey, Edward W Randell, Proton Rahman, Guangju Zhai.

INTRODUCTION: Pro-inflammatory cytokines are responsible for initiating an effective defense against exogenous pathogens, and their regulation has a vital role in maintaining physiological homeostasis. The involvement of pro-inflammatory cytokines in pathological conditions have been explored in great detail, however, studies investigating metabolic pathways associated with these cytokines under normal homeostatic conditions are scarce.OBJECTIVES: The aim of the current study was to identify metabolites and metabolic pathways associated with circulating pro-inflammatory cytokines under homeostatic conditions using a metabolomics approach.
METHODS: The study participants (n = 133) were derived from the Newfoundland Osteoarthritis Study (NFOAS) and the Complex Diseases in the Newfoundland population: Environment and Genetics (CODING) study. Plasma concentrations of cytokines including tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), interleukin-1 beta (IL-1β), and macrophage migration inhibitory factor (MIF) were assessed by enzyme-linked immunosorbent assay. Targeted metabolomic profiling on fasting plasma samples was performed using Biocrates MxP® Quant 500 kit which measures a total of 630 metabolites. Associations between natural log-transformed metabolite concentrations and metabolite sums/ratios and cytokine levels were assessed using linear regression with adjustment for age, sex, body mass index (BMI), and osteoarthritis status.
RESULTS: Seven metabolites and 11 metabolite sums/ratios were found to be significantly associated with TNF-α, IL-1β, and MIF (all p ≤ 5.13 × 10- 5) after controlling multiple testing with Bonferroni method, indicating the association between glutathione (GSH), polyamine, and lysophosphatidylcholine (lysoPC) synthesis pathways and these pro-inflammatory cytokines.
CONCLUSION: GSH, polyamine, and lysoPC synthesis pathways were positively associated with circulating TNF-α, IL-1β, and MIF levels under homeostatic conditions.

Keywords: Glutathione; Lysophosphatidylcholine; Metabolomics; Polyamine; Pro-inflammatory cytokine

DOI: https://doi.org/10.1007/s11306-022-01932-5