NUDT5 regulates the global efficacy of nucleoside analog drugs by coordinating purine synthesis and PRPP allocation

Abstract

Cancer cells require nucleotides to meet proliferation demands, which has been effectively exploited by nucleoside analog (NA) drugs. Despite their success, we still do not completely understand factors dictating their anticancer effect. Here, we report that a NUDT5 scaffolding function indirectly regulates the global efficacy of anti-cancer NA drugs. Mechanistically, PROTAC- or RNAi-mediated NUDT5 depletion, not inhibition, desensitizes cells to 6-thioguanine (6TG) and other NA drugs proportionally with NUDT5 abundance. NUDT5-depleted cells appear locked into de novo purine biosynthesis (DNPB), thus impairing salvage of nucleotide precursors and NA drug activation. Specifically, NUDT5 interacts with phosphoribosyl amidotransferase (PPAT), the rate-limiting DNPB enzyme, to putatively regulate its activity, DNPB flux, and resultant phosphoribosyl pyrophosphate (PRPP) allocation. Collectively, these results suggest that NUDT5 controls NA drug efficacy by coordinating nucleotide synthesis and PRPP utilization, making it a potential biomarker of clinical efficacy and target for finetuning antimetabolite therapies. Statement of significanceNUDT5 non-enzymatically regulates the global efficacy of anti-cancer nucleoside analog drugs by interacting with PPAT to control DNPB and allocation of PRPP, thereby establishing it as a biomarker of clinical significance.