E2F1-Associated Purine Synthesis Pathway Is a Major Component of the MET-DNA Damage Response Network

Abstract

Various lines of investigation support a signaling interphase shared by receptor tyrosine kinases and the DNA damage response. However, the underlying network nodes and their contribution to the maintenance of DNA integrity remain unknown. We explored MET-related metabolic pathways whose interruption compromises proper resolution of DNA damage. Discovery metabolomics combined with transcriptomics identified changes in pathways relevant to DNA repair following MET inhibition (METi). METi by tepotinib was associated with formation of γH2AX foci and with significant alterations in major metabolic circuits such as glycolysis, gluconeogenesis, and purine, pyrimidine, amino acids, and lipids metabolism. 5'-Phosphoribosyl-N-formylglycinamide (FGAR), a de novo purine synthesis pathway metabolite, was consistently decreased in in vitro and in vivo MET-dependent models, and a METi-related depletion of dNTPs was observed. METi instigated the downregulation of critical purine synthesis enzymes including phosphoribosylglycinamide formyltransferase (GART) which catalyzes FGAR synthesis. Genes encoding these enzymes are regulated through E2F1, whose levels decrease upon METi in MET-driven cells and xenografts. Transient E2F1 overexpression prevented dNTPs depletion and the concomitant METi-associated DNA damage in MET-driven cells. We conclude that DNA damage following METi results from dNTPs reduction via downregulation of E2F1 and a consequent decline of de novo purine synthesis.