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  • The diversity of metabolic adaptations employed by cancer ce

    2024-09-13

    The diversity of metabolic adaptations employed by cancer cells in response to rapidly changing conditions, contributes to their biological aggressiveness and therapeutic resistance by enabling them to proliferate when nutrients are plentiful and to shift their resources to survival when nutrients are scarce (Palm et al., 2015). The results presented here demonstrate that mTORC2 controls cystine uptake and glutathione metabolism by directly phosphorylating xCT, thus linking altered growth factor receptor signaling with amino Zerumbone metabolism and ROS buffering in cancer.
    STAR★Methods
    Author Contributions
    Acknowledgments We thank Dr. Hideyo Sato for kindly providing us with the xCT KO MEFs and helpful suggestions. We thank past and present members of the Paul S. Mischel lab for helpful discussions and Minh Thai, Carolina Espindola-Camacho, and Abby Krall from the Heather R. Christofk lab for help with the metabolomics experiments. We also want to thank Zhipeng Meng, Haixin Yuan, and Jenna Jewell from the Kun-Liang Guan Lab for help with the in vitro kinase assay. This work was supported by grants from National Institute for Neurological Diseases and Stroke (NS73831) and the National Cancer InstituteF31CA186668 (G.R.V.), the Defeat GBM Program of the National Brain Tumor Society, the Ben and Catherine Ivy Foundation, and generous donations from the Ziering Family Foundation in memory of Sigi Ziering (P.S.M.). C.P.A. and H.Z. were supported by NIH grant R01-GM116897. H.R.C. was supported by a Research Scholar Grant, RSG-16-111-01-MPC, from the American Cancer Society. K.-L.G. was supported by NIH grant R35ca196878. K.-L.G. is a co-founder of Vivace Therapeutics.
    Introduction The consumption of high-energy diets rich in fat, sugars, or both is increasing worldwide, paralleling the increases in obesity and metabolic diseases like type 2 diabetes mellitus and cardiovascular diseases [1]. High-fat high-sugar (HFHS) diets are highly palatable and have a poorly controlled intake [2]. Despite the high interindividual variability in the sensitivity to weight and adiposity gains, HFHS overfeeding is one of the main factors responsible for the increased prevalence of adiposity and metabolic disorders involving insulin resistance (IR) and leading to chronic metabolic diseases [3]. Among the most recently studied metabolic dysfunctions and plasma metabolites alterations associated with IR occurrence, the place of branched-chain amino acids (BCAA) is questioned [4]. An increased level of plasma BCAA is observed in individuals who are insulin resistant and shown to be altered simultaneously with IR and diabetes installation [5]. To date, the underlying mechanisms explaining these increased BCAA levels is still under debate [6], [7] and whether the increased level of BCAA should be considered as causal of IR or a consequence of its installation remains controversial [7]. Indeed, a BCAA-altered metabolism in adipose tissue (AT) associated with a reduction of the capacity of the BCAA catabolic enzymes has been clearly shown in case of obesity-associated IR [4], [6]. However, the role of other tissues in BCAA metabolism or their metabolite production has been less studied in such situations. This is the case of the liver, which is poorly involved in BCAA transamination (BCAA → keto acids [KA]) but is a major actor in KA catabolism [8]. Finally, it is unclear whether increased BCAA results from altered AT metabolism associated with obesity or if it is the consequence of the IR development, which will ultimately lead to obesity and dysfunction of adipose cells in BCAA metabolism [4]. Despite the fact that elevated levels of BCAAs have been repeatedly correlated to IR in human cohort studies, the data concerning the mechanisms by which BCAA would increase in plasma came mainly from rodents that were genetically modified in many cases. Additionally, little is known about the time-course increase of BCAA, and only a few studies were focused on a longitudinal follow-up [9]. To determine whether increased circulating levels of BCAAs are at the origin of the IR phenotype, we explored the BCAA metabolism on an animal model that is close to humans, allowing the accession to repeated sampling over long periods. Therefore, we performed a 2-mo follow-up on Yucatan minipigs overfed an HFHS diet, previously shown to induce a human-like obese/IR phenotype [10]. We focused on both fasting and postprandial (PP) glucose, lipids, and BCAA metabolisms at the plasma level. BCAA catabolism was explored in key tissues at the enzyme, protein, and gene expression levels.