Project description:In order to investigate the crucial role of PFKFB4 in glioblastoma stem-like cell (GSC) survival, gene expression microarray-based transcriptome analysis was conducted on GSCs transduced for 4 days with PFKFB4 shRNA compared with GSCs transduced with shNT.
Project description: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.
Project description:Radioresistance is a major cause of radiotherapy failure in lung cancer, and its mechanism has not been fully elucidated. Glucose metabolism is closely related to radioresistance, and targeting key molecules in glucose metabolism is expected to increase radiosensitivity. Our study demonstrated that the expression of the gluconeogenic enzyme PFKFB4 was upregulated in lung cancer. Genetic silencing and pharmacological inhibition of PFKFB4 significantly enhanced lung cancer radiosensitivity. Mechanistically, the fumaric acid/Rad51 axis is crucial for PFKFB4-induced radioresistance. PFKFB4 inhibits histone demethylase KDM1A by upregulating fumaric acid, which in turn increases the level of H3K4me1 at the Rad51 promoter region and induces Rad51 transcriptional activation, and ultimately leads to lung cancer radioresistance. Furthermore, by constructing a library of ubiquitinated compounds, the deubiquitinating enzyme USP10 was identified as a key upstream molecule for stabilizing PFKFB4 expression, and USP10 silencing downregulated fumaric acid and Rad51 in a PFKFB4-dependent manner, which in turn increased lung cancer radiosensitivity. In conclusion, the present study reveals that USP10-mediated PFKFB4deubiquitination promotes lung cancer radioresistance through activation of the fumaric acid/Rad51 axis and provides important evidence for the clinical translation of PFKFB4.
Project description:To explore the mechanisms by which PFKFB4 promotes breast cancer metastasis, we CRISPR-Cas knock-out PFKFB4 in two breast cancer lines for RNA-seq to identify downstream target genes that are regulated by PFKFB4