Fig. 8: Activation of one-carbon metabolism associated with muscle hypermetabolism is also a feature of cachexia in the humanised SW480-tumour mouse model.
a,b, Relative mRNA expression level of key enzymes of one-carbon metabolism and related pathways in liver (a) and skeletal muscle (b) of patients with cancer with or without sarcopenia (no sarcopenia: n = 9 liver samples, 7 muscle samples; sarcopenia, n = 19 liver samples, 17 muscle samples). See also Supplementary Table 3 for patients’ clinical data. c, Experimental set-up. Mice were injected subcutaneously either with PBS (healthy control, no tumour, Ctrl, grey, n = 4 animals) or with the cachexia-inducing SW480 cancer cells (human colon carcinoma, cachexia, Cax, dark orange, mean body weight loss of 10%, n = 5 animals). On the day of euthanasia, mice were fasted for 6 h and injected with the isotopic tracer [13C6]-glucose. Tissues (plasma, liver, eWAT, iWAT, heart, GC and soleus muscles) were collected exactly 1 h later. Tissues were then processed for tracer metabolomics. See also Extended Data Fig. 10. d,e, Relative mRNA expression level of key enzymes of one-carbon metabolism and related pathways in liver (d) and GC muscle (e). f–i, Metabolite levels of one-carbon metabolism and related pathways in plasma (f), liver (g), GC muscle (h) and eWAT (i). Metabolite IDs as in the list in Fig. 3b. Statistical analysis on raw data (2−ΔCt values and MS signal intensities, arbitrary units (AU)). j–q, Incorporation of labelled carbons from [13C6]-glucose into metabolites of the TCA cycle in GC muscles. Unlabelled metabolites are referred as M + 0 and isotopically labelled metabolites as M + X, where X represents the number of labelled carbon atoms. Data are presented as the percentage of total metabolite levels. Stacked bar graphs (j, l, n and p) show the overall isotopologue levels; bar graphs (k, m, o and q) show the levels of each individual isotopologue (citrate (j and k), succinate (l and m), fumarate (n and o) and malate (p and q)). r–t, Distribution of all labelled TCA metabolite isotopologues detected in GC muscle (r), soleus (s) and heart (t). Data are the mean ± s.e.m. Statistical analysis: two-tailed, non-adjusted, Student’s t-test or Mann–Whitney test (d–i, k, m, o and q), two-way ANOVA with Šidák’s (a, b and r–t) post-hoc tests. *P < 0.05, **P < 0.01, ***P < 0.001, ****P < 0.0001 versus Ctrl or no sarcopenia groups.
