Extended Data Fig. 10: The PFKFB4–SRC-3 axis drives transcriptional programming in patients with breast cancer.
From: Metabolic enzyme PFKFB4 activates transcriptional coactivator SRC-3 to drive breast cancer
a, b, Expression of pSRC-3, SRC-3 and PFKFB4 in ER+ breast tumour specimens and matched adjoining normal tissues as detected by immunoblotting. n = 14 patients with ER+ breast cancer. c, Semi-quantitative levels of bands shown in a and b, analysed by densitometry using UVP Vision Works LS software, and normalized relative to actin to calculate the fold change (tumour/normal) and plotted to obtain the correlation between PFKFB4 and pSRC-3-Ser857 expression. n = 14 normal and tumour tissues. R = 0.63, P = 0.02 Spearman’s rank correlation coefficient. d, log fold change in protein expression of the PFKFB4–SRC-3 signature compared to the control knockdown (non-targeting shRNA) as determined using a parametric t-test as implemented in the python (spicy) statistical system. Significance P < 0.05 and fold change exceeding 1.25× were used to classify true regulators of SRC-3 activity. n = 3 biologically independent samples. e, Kaplan–Meier survival plot showing poor survival of patients with breast cancer with basal subtype (triple-negative) disease exhibiting an increased expression of a common proteomic signature induced by the PFKFB4 and SRC-3 axis. The cohort of patients was collected by the TCGA. P = 0.0365, log-rank test; P = 0.02971, Cox proportional hazards, two-sided. f, Cartoon model describing the crosstalk between glycolysis and purine generation highlighting the essential steps regulated by pSRC-3-Ser857. This PFKFB4-dependent SRC-3 phosphorylation enhances mRNA expression of genes involved in purine metabolism driving breast tumour growth, proliferation and metastasis. AICAR, 5-aminoimidazole-4-carboxamide ribonucleotide; AMP, adenosine monophosphate; F1,6-P, fructose 1,6 bisphosphate; IMP, inosine monophosphate. g, Model showing that, in glycolytic breast tumours, activated PFKFB4 drives SRC-3 phosphorylation at Ser857, which then activates ER-positive primary tumour growth in conjunction with E2-liganded ER, as well in ER-negative/recurrent tumours in conjunction with ATF4, driving aggressive metastatic disease. Data are mean ± s.d.
