Asparagine Dependency is a Targetable Metabolic Vulnerability in TP53-Altered Castration-Resistant Prostate Cancer

Abstract The TP53 tumor suppressor is frequently altered in lethal, castration-resistant prostate cancer (CRPC). However, to date there are no effective treatments that specifically target TP53 alterations. Using transcriptomic and metabolomic analyses, we showed here that TP53-altered prostate cancer (PCa) exhibits an increased dependency on asparagine and overexpresses asparagine synthetase (ASNS), the enzyme catalyzing the synthesis of asparagine. Mechanistically, loss or mutation of TP53 transcriptionally activated ASNS expression, directly as well as via mTORC1-mediated ATF4 induction, driving de novo asparagine biosynthesis to support CRPC growth. TP53-altered CRPC cells were sensitive to asparagine restriction by knockdown of ASNS or L-asparaginase treatment to deplete the intracellular and extracellular sources of asparagine, respectively, and cell viability was rescued by asparagine addition. Notably, pharmacological inhibition of intracellular asparagine biosynthesis using a glutaminase inhibitor and depletion of extracellular asparagine with L-asparaginase significantly reduced asparagine production and effectively impaired CRPC growth. This study highlights the significance of ASNS-mediated metabolic adaptation as a synthetic vulnerability in CRPC with TP53 alterations, providing a rationale for targeting asparagine production to treat these lethal prostate cancers.