Delivering isotopic tracers for metabolic studies in rodents without overt stress is challenging. Current methods achieve low label enrichment in proteins and lipids. Here, we report noninvasive introduction of 13C6-glucose via a stress-free, ad libitum liquid diet. Using NMR and ion chromatography-mass spectrometry, we quantify extensive 13C enrichment in products of glycolysis, the Krebs cycle, the pentose phosphate pathway, nucleobases, UDP-sugars, glycogen, lipids, and proteins in mouse tissues during 12 to 48 h of 13C6-glucose feeding. Applying this approach to patient-derived lung tumor xenografts (PDTX), we show that the liver supplies glucose-derived Gln via the blood to the PDTX to fuel Glu and glutathione synthesis while gluconeogenesis occurs in the PDTX. Comparison of PDTX with ex vivo tumor cultures and arsenic-transformed lung cells versus xenografts reveals differential glucose metabolism that could reflect distinct tumor microenvironment. We further found differences in glucose metabolism between the primary PDTX and distant lymph node metastases.
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This work was supported in part by grants: 1R01ES022191-01 (to T.W.-M.F. and R.M.H.), 1P01CA163223-01A1 (to A.N.L. and T.W.-M.F.), 1U24DK097215-01A1 (to R.M.H., T.W.-M.F., and A.-N.L.), 5R21ES025669-02 (to T.W.M.F.) and the Redox Metabolism Shared Resource(s) of the University of Kentucky Markey Cancer Center (P30CA177558). A.T.L. was supported by T32 5T32CA160003-05 (B.M.E.). R.C.S. was supported by a T32 training grant 5T32ES007266-25 (M.V.).
Data availability: Metabolic data are available from the authors upon request and will be made available to the community via the Metabolomics Workbench (www.metabolomicsworkbench.org). The authors declare that all the other data supporting the findings of this study are available within the article and its Supplementary Information files and from the corresponding author upon reasonable request.
Supplementary Information accompanies this paper at doi: 10.1038/s41467-017-01518-z
13C-enriched standards were obtained from NIH Common Fund Metabolite Standards Synthesis Core (http://www.metabolomicsworkbench.org/standards/index.php).
Sun, Ramon C.; Fan, Teresa W.-M.; Deng, Pan; Higashi, Richard M.; Lane, Andrew N.; Le, Anh-Thu; Scott, Timothy L.; Sun, Qiushi; Warmoes, Marc O.; and Yang, Ye, "Noninvasive Liquid Diet Delivery of Stable Isotopes into Mouse Models for Deep Metabolic Network Tracing" (2017). Center for Environmental and Systems Biochemistry Faculty Publications. 2.