Signatures of micropeptides encoded by lncRNAs in cancer progression and metastasis

Background: Long non-coding RNAs (lncRNAs) regulate gene expression, chromatin organization, and cellular signaling. Although traditionally considered non-coding, 21% of the ~190,000 annotated lncRNA transcripts contain poorly characterized open reading frames with unknown function. Methods: We systematically identified lncRNAs encoding micropeptides (MPs) using integrated computational and experimental evidence. Expression profiles across 17 cancer types from The Cancer Genome Atlas (TCGA) were analyzed to identify cancer-associated and transitional lncRNAs (Tr-lncRNAs). Structural modeling using AlphaFold was further applied to predict folding. Results: We identified 478 lncRNA genes encoding 1782 MPs (10–100 amino acids). These MPs exhibit distinct amino acid and dipeptide compositions and are enriched for specific 4-mer motifs compared with canonical proteins. A subset of lncRNAs, including TNN-AS1, PVT1, XIST, and SNHG family members, encode multiple MPs. Analysis across cancer stages identified 2399 Tr-lncRNAs, most of them were cancer type and stage specific. Among these, 314 highly confident MPs from 72 Tr-lncRNAs were further analyzed. Pan-cancer analysis suggested MP-like functions for Tr-lncRNAs such as LINC01234, HAND2-AS1, XIST, UCA1, and HOXA11-AS. While most MPs are predicted to be intrinsically disordered, 3D structural modeling revealed several MPs with stable folds, including ubiquitin-like and RNase H-like structures. Conclusions: Tr-lncRNA–derived MPs represent a previously underexplored class of potentially functional molecules associated with cancer clinical annotation and may serve as biomarkers for disease progression.