Protecting the genome through metabolic enzymes
The Phosphofructo-2-kinase/Fructose-2,6-biphosphatase 3 (PFKFB3) enzyme is upregulated in cancer and plays a key role in the regulation of glycolysis. Here, we identify elevated PFKFB3 levels in radiotherapy-resistant patients and relocalization of PFKFB3 into nuclear foci upon ionizing radiation (IR). Loss of PFKFB3 decreases homologous recombination activity, impairs recruitment of DNA repair factors, recovery from radiation-induced cell cycle arrest and cancer cell survival. Through extensive drug discovery efforts we further develop and validate a novel potent and selective PFKFB3 inhibitor, KAN0438757, which selectively kills cancer cells while sparing normal cells. Inhibition of PFKFB3 kinase activity results in limited nucleotide synthesis as proliferation and replication arrest upon KAN043757 treatment can be rescued by nucleoside supplementation. In support of this, PFKFB3 colocalizes with ribonucleotide reductase M2 into nuclear foci in an ATM- and PFKFB3 kinase activity-dependent manner. Thus, the PFKFB3 kinase activity plays a key role in replicative and repair DNA synthesis, connecting cancer metabolism to maintenance of genome integrity, suggesting that PFKFB3 inhibition by KAN043757 could be an attractive approach to decrease resistance to therapeutically induced DNA breaks.