A Novel Nuclear-Localized Micropeptide, MP60, Promotes Hepatocellular Carcinoma Progression via the Epithelial-Mesenchymal Transition.

Background: Micropeptides, encoded by non-coding RNAs, play a pivotal role in various cellular functions. While several micropeptides have already been linked to HCC, their roles remain incompletely understood. Our study identifies MP60, a conserved micropeptide strongly associated with HCC progression. Methods and Results: By analyzing The Cancer Genome Atlas (TCGA) dataset, we assessed the coding potential of long non-coding RNAs (lncRNAs) with significant expression changes in HCC. Our findings reveal that ENST0000614292, a transcript of LINC01138, exhibited the highest coding potential, encoding a putative 60-amino-acid micropeptide, which we have named MP60 and confirmed the expression of MP60 in HCC tissues, with a nuclear localization. MP60 directly interacts with RNA-binding motif protein 10 (RBM10) and downregulates its expression. Additionally, MP60 modulates EMT. Functional analyses demonstrated that MP60 promotes cellular proliferation and migration, while reducing cellular adhesion, translated by enhanced tumorigenesis in vivo. Notably, MP60 expression is markedly increased in HCC tissues and is associated with a poorer prognosis. Conclusions: These findings identify MP60 as a potential biomarker and therapeutic target in HCC, linking its oncogenic effects to EMT modulation and tumor progression.