Fig. 6: Ex vivo ¹H NMR profiling reveals altered choline metabolism in SLFN11^−/− EWS tumors.

a Schematic of ex vivo ¹H NMR (600 MHz) analysis in athymic nude mice. EWS cells were implanted orthotopically, and excised tumors were extracted for metabolic profiling by ¹H NMR. Representative ¹H NMR spectra of choline metabolite obtained from water-soluble tumor extract from ES-8 WT (b) and SLFN11^−/− (c) xenografts. Spectra are expanded to display signals from 3.20 to 3.25 ppm. Metabolites involved in choline metabolism including GPC (3.235 ppm), (PCh, 3.226 ppm), and free choline (3.208 ppm), highlighted with arrows. d Bar graph showing quantification of GPC, PCh, and total choline levels in WT and SLFN11^−/− ES-8 tumor xenografts. Data represent mean ± SD (n = 3). e Quantification of PCh/GPC ratio in ES-8 WT and SLFN11^−/− xenograft tumors. Data represent mean ± SD (n = 3). Statistical significance determined using paired two-tailed t-test (*p < 0.05). SD, standard deviation; n number of replicates. f Schematic illustrating the Kennedy pathway (pink) involved in choline metabolism, where choline is converted to PC via PCh and CDP-Ch. An alternate route involving G3P and fatty acids (blue) also contributes to PC generation. GPC and Lyso-PC degradation branches are shown in beige. PC phosphatidylcholine; CDP-Ch CDP-choline; PCh phosphocholine; GPC glycerophosphocholine; G3P glycerol-3-phosphate. g Schematic summary of SLFN11-loss-induced metabolic rewiring in EWS.