Metabolic supervision by PPIP5K, an inositol pyrophosphate kinase/phosphatase, controls proliferation of the HCT116 tumor cell line
Menée sur une lignée cellulaire de cancer du côlon, cette étude met en évidence un mécanisme par lequel l'inositol pyrophosphate kinase/phosphatase PPIP5K, en interagissant avec les voies métaboliques, favorise la prolifération des cellules cancéreuses
Résumé en anglais
Central carbon metabolism has the overlapping functions of converting substrate into biomass and the extraction and storage of chemical energy. These metabolic pathways are rewired by cancer cells to selectively support increased biomass demands. This reprogramming is a potential therapeutic target if a molecular-level understanding of the relevant control processes can be attained. Through genomic editing of an HCT116 colonic tumor cell line, we uncover metabolic supervision by a single pair of cell-signaling enzymes, the PPIP5Ks. Our global measurements of steady-state metabolite levels, plus isotope tracing analysis, show in detail how HCT116 cells recruit PPIP5Ks to select specific metabolic pathways to provide adequate precursor supply for biomass production. Crucially, in the absence of PPIP5K activity, HCT116 tumorigenesis is reduced.Identification of common patterns of cancer metabolic reprogramming could assist the development of new therapeutic strategies. Recent attention in this field has focused on identifying and targeting signal transduction pathways that interface directly with major metabolic control processes. In the current study we demonstrate the importance of signaling by the diphosphoinositol pentakisphosphate kinases (PPIP5Ks) to the metabolism and proliferation of the HCT116 colonic tumor cell line. We observed reciprocal cross talk between PPIP5K catalytic activity and glucose metabolism, and we show that CRISPR-mediated PPIP5K deletion suppresses HCT116 cell proliferation in glucose-limited culture conditions that mimic the tumor cell microenvironment. We conducted detailed, global metabolomic analyses of wild-type and PPIP5K knockout (KO) cells by measuring both steady-state metabolite levels and by performing isotope tracing experiments. We attribute the growth-impaired phenotype to a specific reduction in the supply of precursor material for de novo nucleotide biosynthesis from the one carbon serine/glycine pathway and the pentose phosphate pathway. We identify two enzymatic control points that are inhibited in the PPIP5K KO cells: serine hydroxymethyltransferase and phosphoribosyl pyrophosphate synthetase, a known downstream target of AMP-regulated protein kinase, which we show is noncanonically activated independently of adenine nucleotide status. Finally, we show the proliferative defect in PPIP5K KO cells can be significantly rescued either by addition of inosine monophosphate or a nucleoside mixture or by stable expression of PPIP5K activity. Overall, our data describe multiple, far-reaching metabolic consequences for metabolic supervision by PPIP5Ks in a tumor cell line.All study data are included in the article and/or SI Appendix.
