Fig. 1: Elevated PHGDH catalytic activity is required for HCC growth.

a The differential abundance scores of metabolites and genes based on KEGG pathway were plotted against each other. A score of 1 denotes all metabolites in a given pathway increase, while a score of −1 denotes all metabolites in a given pathway decrease. b GO analysis of differential metabolites between HCC tissues and normal tissues. Statistical analysis was performed using the two-sided hypergeometric test with Bonferroni correction. c Serine levels in human HCC tissues and paired normal tissues (n = 20 samples, cohort 2). Statistical analysis was performed using the paired two-tailed Student’s t-test. d, e Representative images (d) and quantitative analysis (e) of IHC staining using PHGDH antibody (PA5-27578, ThermoFisher) in HCC tissues and paired normal tissues (n = 42 samples, cohort 3). Scale bars, 50 μm. Statistical analysis was performed using the paired two-tailed Student’s t-test. f PHGDH activity in human HCC tissues and paired normal tissues (n = 20 samples, cohort 2). Statistical analysis was performed using the paired two-tailed Student’s t-test. g Growth rates of Huh7 and PLC/PRF/5 cells grown in complete (CM) or serine- and glycine-depleted (-SG) medium treated with or without NCT-503 (20 μM). Data are presented as the mean ± SD (n  =  4 independent experiments). Statistical analysis was performed using the two-way ANOVA with Bonferroni correction. h Schematic of U-[¹³C]-glucose incorporation into serine and glycine in cells. i, j Incorporation of U-[¹³C]-glucose carbon into serine (i) and glycine (j) in parental and PHGDH KO cells. Data are presented as the mean ± SD (n  =  3 independent experiments). Statistical analysis was performed using the two-tailed Student’s t-test. k Growth rates of parental and PHGDH KO cells grown in CM or -SG medium. Data are presented as the mean ± SD (n  =  5 independent experiments). Statistical analysis was performed using the two-way ANOVA with Bonferroni correction. l–n Huh7 parental and PHGDH KO cells were subcutaneously inoculated into nude mice fed with a control (+SG) or serine- and glycine-free diet (-SG diet). Tumor images (l), weight (m), and volume (n) were presented. Data are presented as the mean ± SD (n = 6 mice). Statistical analysis in m was performed using the two-tailed Student’s t-test, and statistical analysis in n was performed using the two-way ANOVA with Bonferroni correction. o Representative images of IHC staining for Ki-67 in tumor xenografts. Scale bars, 50 μm. Source data are provided as a Source Data file.