Dysregulated Proline Metabolism Exacerbates Hepatocellular Carcinoma Metastasis via EPRS1-Mediated mRNA Translation.

Background: Metabolic reprogramming is a hallmark of hepatocellular carcinoma (HCC), and amino acid reprogramming plays an important role in its metastatic progression. However, the function of amino acid reprogramming in HCC metastatic progression remains unclear. This study aimed to elucidate the function and mechanism of amino acid reprogramming, particularly focusing on proline metabolism, in driving HCC metastasis. Methods: HCC cohort and multiple HCC models were enrolled to investigate the role of amino acid reprogramming in HCC metastatic progression. The pro-metastatic effect of l-proline in HCC was consistently validated across in vitro and in vivo studies. Ribosome profiling (Ribo-seq) and l-proline pull-down were used to investigate the mechanism of proline-mediated HCC metastasis. Results: Based on metabolomics and proteomics, we found that proline metabolism was enhanced during HCC metastasis, as evidenced by increased proline levels and proline metabolism-related enzymes in both HCC metastatic patients and mice. Moreover, high levels of proline were found to promote HCC metastasis. Mechanistically, l-proline directly interacted with glutamyl-prolyl-tRNA synthetase 1 (EPRS1) at its Glu1123 residue, thereby selectively enhancing the translation of phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit α (PIK3CA), AKT serine/threonine kinase 3 (AKT3), and integrin subunit β1 (ITGB1). Importantly, the enhanced protein translation could be abolished by bersiporocin, an EPRS1 inhibitor that prevents l-proline binding to EPRS1. Finally, the inhibitory effect of bersiporocin on HCC metastasis was confirmed in patient-derived orthotopic xenograft models. Conclusions: Our findings not only revealed the critical role of l-proline-bound EPRS1 in promoting HCC metastasis but also indicated that inhibiting this binding could be a promising strategy to prevent metastasis.