Glycolysis enzyme PFKFB4 enhances HIF1a transcriptional activity by blocking the ubiquitin E3 ligase FBXO28 in glioblastoma

ABSTRACT: Glioblastoma is one of the most aggressive primary brain tumours in adults, with a dismal median overall survival of only 14 months after diagnosis1,2. Glioblastoma stem-like cells (GSCs), are particularly resistant to current therapies3,4, capable of self-renewal and tumour initiation5,6 and are hence thought to be major contributors to patient relapse. Glycolysis gene 6-Phosphofructo-2-Kinase/Fructose-2,6-Biphosphatase 4 (PFKFB4) is an essential gene for GSC survival, and is upregulated in these cells compared with in normal brain7. However, the mode of action of PFKFB4 in GSCs is unknown. Here we show a new role for PFKFB4 in the regulation of Hypoxia Inducible Factor 1 alpha (HIF1α) in GSCs. In a metabolic tracing study, we found that silencing PFKFB4 in GSCs resulted in a global downregulation of glucose metabolism. Gene expression profiling of PFKFB4-silenced GSCs revealed a downregulation of HIF1α target genes, and HIF1α protein levels are dramatically reduced in PFKFB4-silenced GSCs and other cancer cell lines. Finally, through mass spectrometric analysis of immunoprecipitated PFKFB4, we identified the ubiquitin E3 ligase, F box only protein 28 (FBXO28), as a new interaction partner of PFKFB4, which we show to regulate ubiquitylation and subsequent proteasomal degradation of HIF1α. Crucially, this newly discovered function of PFKFB4, coupled with its cancer specificity, provides a new strategy for inhibiting HIF1α in a cancer specific manner. Compounds which disrupt the interaction between PFKFB4 and FBXO28 could be interesting therapeutic agents against glioblastoma and other cancer entities in which PFKFB4 regulates HIF1α stability.

INSTRUMENT(S): LTQ Orbitrap

ORGANISM(S): Homo Sapiens (human)

DISEASE(S): Brain Cancer

SUBMITTER: Uwe Warnken  

LAB HEAD: Martina Schnölzer

PROVIDER: PXD009807 | Pride | 2022-10-13

REPOSITORIES: Pride