Figure 5.
Activation of the serine biosynthesis pathway promotes tumourigenesis in NSCLC. (a) PHGDH knockdown impairs soft agar growth of serine high, but not serine low, cell lines. (b–c) Soft agar growth correlates with serine (b) and glycine (c) labelling at 24 hours. Each cell line was plated at 5,000 cells/well and the number of colonies counted after 14 days. (d) PHGDH knockdown impairs the xenograft growth of a serine high cell line (PC9, left) but not a serine low cell line (H1373, right). Results are the average of 5 tumors. (e) Western analysis of PHGDH expression of cell lines and xenografts from (d) upon injection and at endpoint. (f) Patients with high NRF2 protein expression (Z-score > 0.5) demonstrate elevated serine pathway gene expression in patient samples from TCGA lung adenocarcinoma cohort. Boxes represent mean values, error bars represent SEM. (g) Gene expression of PHGDH, PSAT1 and SHMT2 in the Director’s Consortium lung adenocarcinoma dataset clusters patients into high and low expression cohorts. (h) Kaplan-Meier survival analysis of patients with high (n = 29, red) or low (n = 414, blue) expression of PHGDH, PSAT1 and SHMT2 based on the patient clustering from (g). Median survival is 36 (high) vs. 73.2 (low) months. The p-value was calculated using the Mantel-Cox test.