Endocrine Abstracts

Metabolic dysfunction-associated fatty liver disease (MAFLD) is a growing cause of hepatocellular carcinoma (HCCs); however, the molecular characteristics of MAFLD-derived HCCs are still to be elucidated. To provide novel insights in this field, we performed the first quantitative proteomic analysis of HCC samples from different aetiologies. Particularly, cytosolic and nuclear proteome of liver tissues from HCC patients (n=42; HCC vs adjacent tissue) and healthy controls (n=5) were determined by SWATH-MS-based proteomics. This proteomic profile allowed for the discrimination of two tumoral subgroups. One of them, which included all the MAFLD-derived HCC patients, was associated to aggressive parameters and to a profound dysregulation of the aminoacyl-tRNA synthetases (ARSs), which are essential components of the tRNA aminoacylation machinery. The alteration of the 9 ARSs dysregulated in the proteomic cohort was confirmed in different in silico MAFLD and HCC cohorts, wherein they were associated to aggressive features (i.e., survival and recurrence), and to the metabolic status of the patients (i.e., obesity). Indeed, the general upregulation of the ARSs machinery was identified as a prognostic marker in different mRNA and protein cohorts in that HCC patients with high expression of ARSs had worse survival and a higher recurrence. The valine tRNA-aminoacyl synthetase, VARS1, was selected for studying the functional and molecular consequences of ARSs dysregulation in HCC as its expression was altered in most HCC cohorts and associated to the presence of obesity. For that, in vitro assays (proliferation, migration, colonies/tumorspheres) were performed in liver cancer cell lines (HepG2, Hep3B, SNU-387) after the modulation of the expression (silencing and overexpressing) of VARS1. VARS1 modulation had a reduced effect on proliferation/migration although it significantly altered the dedifferentiation capacity of the cells (colony establishment and spheres formation). The molecular mechanism underlying this effect was assessed through quantitative proteomics in Hep3B and SNU-387 cell lines after overexpressing VARS1. This analysis (and further confirmation by western blot) demonstrated a decreased expression of the scaffold protein MAGI-1, a known tumour suppressor in HCC, associated with the overexpression of VARS1. Thus, VARS1 might be exerting its role through the modulation of MAGI-1-mediated cell junctions. Our study demonstrates the dysregulation of the tRNA-aminoacylation machinery as a diagnostic and prognostic marker in MAFLD and HCC and the potential of these proteins, especially VARS1, as therapeutic targets in tumoral stages.