PAMP orchestrates proline metabolic rewiring to suppress LUAD via PYCR1 inhibition.

Recent advances in next-generation sequencing have revealed that long non-coding RNAs (lncRNAs) can encode functional micropeptides through small open reading frames (sORFs), altering the perception of the non-coding genome. In this study, we identified a 48-amino acid micropeptide named PAMP (proline-associated micropeptide), encoded by the lncRNA PSMA3-AS1, as a novel tumor suppressor in lung adenocarcinoma (LUAD). PAMP is significantly downregulated in LUAD tissues and positively correlates with favorable prognosis. Functional assays demonstrated that PAMP inhibits LUAD cell proliferation in vitro and suppresses tumor growth in vivo. Mechanistically, PAMP directly interacts with PYCR1, a key enzyme in proline biosynthesis. Structural modeling and mutagenesis revealed that the PAMP-F16 and PYCR1-N123 residues are critical for the interaction, resulting in the inhibition of PYCR1 enzymatic activity and decreased proline accumulation. Notably, synthetic PAMP administration recapitulates these anti-tumor effects, effectively reducing intracellular proline levels and impairing tumor progression in cellular and animal models. Together, our findings uncover a previously uncharacterized lncRNA-encoded micropeptide that orchestrates proline metabolic reprogramming to restrain LUAD development, offering new opportunities for metabolic intervention in precision oncology.