Upregulation of ATF4 mediates the cellular adaptation to pharmacologic inhibition of amino acid transporter LAT1 in pancreatic ductal adenocarcinoma cells

L-type amino acid transporter 1 (LAT1) is recognized as a promising target for cancer therapy; however, the cellular adaptive response to its pharmacological inhibition remains largely unexplored. This study examined the adaptive response to LAT1 inhibition using nanvuranlat, a high-affinity LAT1 inhibitor. Proteomic analysis revealed the activation of a stress-induced transcription factor ATF4 following LAT1 inhibition, aligning with the known cellular responses to amino acid deprivation. This activation was linked to the GCN2-eIF2α pathway which regulates translation initiation. Our results show that ATF4 upregulation counteracts the suppressive effect of nanvuranlat on cell proliferation in pancreatic ductal adenocarcinoma cell lines, suggesting a role for ATF4 in cellular adaptation to LAT1 inhibition. Importantly, dual targeting of LAT1 and ATF4 exhibited more substantial anti-proliferative effects in vitro than individual treatments. This study underscores the potential of combining LAT1 and ATF4 inhibition as a therapeutic strategy in cancer treatment.