Project description:The bifunctional enzyme 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase-4 (PFKFB4) controls metabolic flux through allosteric regulation of glycolysis. Here we show that p53 regulates the expression of PFKFB4 and that p53-deficient cancer cells are highly dependent on the function of this enzyme. We found that p53 down-regulates PFKFB4 expression by binding to its promoter and mediating transcriptional repression via histone deacetylases. Depletion of PFKFB4 from p53 deficient cancer cells increased levels of the allosteric regulator fructose 2,6-bisphophate, leading to increased glycolytic activity but decreased routing of metabolites through the oxidative arm of the pentose phosphate pathway. PFKFB4 was also required to support the synthesis and regeneration of nicotinamide adenine dinucleotide phosphate (NADPH) in p53 deficient cancer cells. Moreover, depletion of PFKFB4 attenuated cellular biosynthetic activity and resulted in the accumulation of reactive oxygen species and cell death in the absence of p53. Finally, silencing of PFKFB4 induced apoptosis in p53 deficient cancer cells in vivo and interfered with tumour growth. These results demonstrate that PFKFB4 is essential to support anabolic metabolism in p53-deficient cancer cells and suggest that inhibition of PFKFB4 could be an effective strategy for cancer treatment.
Project description:NRAS-mutated melanoma lacks an approved first-line treatment. Metabolic reprogramming is considered a novel target to control cancer; however, it is mostly unknow how the NRAS oncogene contributes to this cancer hallmark. Here, we show that NRASQ61-mutated melanomas harbor specific metabolic alterations that render cells sensitive to sorafenib upon metabolic stress. Mechanistically, these cells seem to depend on glucose metabolism, as glucose deprivation promotes the switch of the RAF isoform used from CRAF to BRAF. This process contributes to cell survival and sustains glucose metabolism through the phosphorylation of 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase 2/6- phosphofructo-2-kinase/fructose-2,6-bisphosph 3 (PFKFB2/PFKFB3) heterodimers by BRAF. In turn, this phosphorylation favors the allosteric activation of phosphofructokinase-1 (PFK1), generating a feedback loop linking glycolysis and the RAS signaling pathway. In vivo treatment of NRASQ61 mutant melanomas, including patient-derived xenografts, with the combination of 2-deoxy-D-glucose (2-DG) and sorafenib effectively inhibits tumor growth. Thus, we provide evidence of the contributions of NRAS oncogenes to metabolic rewiring and proof of principle for the treatment of NRAS-mutated melanoma with combinations of metabolic stress (glycolysis inhibitors) and already approved drugs such as sorafenib.
Project description:Gene expression profiling of immortalized human mesenchymal stem cells with hTERT/E6/E7 transfected MSCs. hTERT may change gene expression in MSCs. Goal was to determine the gene expressions of immortalized MSCs.
Project description:Transcriptional profiling of human mesenchymal stem cells comparing normoxic MSCs cells with hypoxic MSCs cells. Hypoxia may inhibit senescence of MSCs during expansion. Goal was to determine the effects of hypoxia on global MSCs gene expression.
Project description:Article title: Expression, regulation and function of phosphofructo-kinase/fructose-biphosphatases (PFKFBs) in glucocorticoid-induced apoptosis of acute lymphoblastic leukemia cells. Glucocorticoids (GCs) cause apoptosis and cell cycle arrest in lymphoid cells and constitute a central component in the therapy of lymphoid malignancies, most notably childhood acute lymphoblastic leukemia (ALL). PFKFB2 (6-phosphofructo-2-kinase/fructose-2,6-biphosphatase-2), a kinase controlling glucose metabolism, was identified by us previously as a GC response gene in expression profiling analyses performed in children with ALL during initial systemic GC mono-therapy. Since deregulation of glucose metabolism has been implicated in apoptosis induction, this gene and its relatives PFKFB1, 3, and 4 were further analyzed. Expression analyses in additional ALL children, non-leukemic individuals and leukemic cell lines confirmed frequent PFKFB2 induction by GC in most systems sensitive to GC-induced apoptosis, particularly in T-ALL cells. The 3 other family members, in contrast, were not or weakly expressed (PFKFB1 and 4) or not induced by GC (PFKFB3). Conditional PFKFB2 over-expression in the CCRF-CEM T-ALL in vitro model revealed that its 2 splice variants (15A and 15B) did not have any detectable effect on survival or cell cycle progression. Moreover, neither PFKFB2 splice variant significantly affected sensitivity to, or kinetics of, GC-induced apoptosis. Our data suggest that, at least in the model system investigated, PFKFB2 is not an essential upstream regulator of the anti-leukemic effects of GC. Gene expression profiles of 4 non-leukemic individuals (1 healthy and 3 with epilepsy) were generated from mononuclear cells isolated from peripheral blood samples before, and after 2, 6, and 24 hours of in-vivo glucocorticoid treatment.