Fig. 7. HIFAL is essential for HIF-1α dependent glycolysis and knockdown of HIFAL and HIF-1α synergistically reduces tumor growth in vivo.

a HIFAL knockdown decreases glycolysis in vitro. ECAR was measured, including the glycolytic reserve. The curves are means ± SD of experimental triplicates. b Knockdown of HIFAL decreases breast tumor glycolysis. Mice were scanned for 18 FDG-uptake by FDG-PET and CT after the treatment of control and HIFAL LNAs. The MDA-MB-231 tumors were circled with dashed red lines in the scan images. The 18F-FDG-uptake in 7 mice per group were shown in the right plots. c A schematic model demonstrates the role of HIFAL in assembling the HIF-1 transactivation complex and drives the transcription of HIF-1 target genes. HIFAL recruits PKM2/PHD3 complex, introduces their nuclear transportation by binding with hnRNPF and enhances the transcription of HIF-1 target genes by assembling the HIF-1α co-activators. Reciprocally, HIF-1α induces HIFAL transcription, which forms a positive feed-forward loop to maintain the HIF-1α transactivating activities. d HIFAL is overexpressed in breast cancer tissues, especially in basal-like cancers, as detected by q-PCR in 52 paired tumor and para-tumor tissue. e–g High HIFAL level correlates with poor overall survival of breast cancer patients in luminal A (e), luminal B cancers (f) and basal like cancers (g), Kaplan–Meier, log-rank test. h, i Knockdown of HIFAL and HIF-1α synergistically reduces tumor growth of MDA-MB-231 xenografts in nude mice. HIFAL-LNAs and/or HIF-1α-LNAs were injected intraperitoneally after the tumor volumes reached 100 mm³. The growth curves (h) and tumor weights (i) are means ± SD of 8 mice in each group, p values were determined by one-way ANOVA + Dunnett’s post hoc tests. j Knockdown of HIFAL suppresses nuclear translocation of PHD3 and PKM2 in xenografts detected by immunohistochemistry. k, l Knockdown of HIFAL and HIF-1α decreases glycolysis and the proliferation of tumor cells. Immunohistochemistry for PHD3, PKM2, GLUT1, LDHA, and ki67 was performed in xenografts (j–l). Scale bars, 20 μM. P values were determined by two-sided unpaired t-test (b, d). Source data are provided as a Source Data file.