Chromatin accessibility profiling by ATAC-seq in LNCaP-shNT and LNCaP-shTP53 cells

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 show 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/mutation of TP53 transcriptionally activate ASNS expression, directly as well as via ATF4, driving de novo asparagine biosynthesis to support CRPC growth. TP53-altered CRPC cells are sensitive to asparagine restriction by knockdown of ASNS and L-asparaginase treatment to deplete the intracellular and extracellular sources of asparagine respectively. This effect was rescued by asparagine addition. Notably, pharmacological inhibition of intracellular asparagine biosynthesis using a glutaminase (GLS) 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 co-targeting intracellular and extracellular asparagine production to treat these lethal prostate cancers.