Endocrine Abstracts

JOINT1033

Background and aims: With the increasing incidence of metabolic dysfunction-associated steatotic liver disease (MASLD) and its association with hepatocellular carcinoma (HCC) development, novel potential clinical strategies are required. We have demonstrated that aminoacyl-tRNA synthetases (ARSs), which catalyze the transfer of amino acids to tRNAs, are altered in MASLD/HCC. Here, we explore the potential of aspartyl-tRNA synthetase (DARS1) as diagnostic biomarker and therapeutic target, as its molecular implication in MASLD/HCC.

Method: Tissular DARS1 levels were analyzed in in silico cohorts (mRNA/protein) of MASLD and HCC and in cytosolic/nuclear protein fractions of HCC patients (n=42). DARS1 levels were measured in plasma samples of two cohorts (Cohort1: 21 controls, 15 MASLD, 14 cirrhosis, 32 HCC; Cohort2: 8 controls, 8 HCC). Functional assays were performed in liver-derived cell lines (HepG2, Hep3B, SNU-387) after DARS1 modulation (silencing, overexpression, pharmacological inhibition). DARS1-overexpressing Hep3B cells were used for in vivo xenograft and orthotopic tumor formation. DARS1 immunoprecipitation and quantitative proteomics were performed in cytosolic/nuclear Hep3B fractions.

Results: DARS1 abundance was reduced in MASLD but increased in HCC tissues (mRNA/protein) and plasma [Area Under Curve (AUC) of plasma levels: HCC vs. controls: 0.8376; HCC vs. MASLD: 0.9016; HCC vs. cirrhosis: 0.8095]. DARS1 levels were higher in aggressive tumors (i.e. invasive, dedifferentiated), in patients with adrenal/lung metastasis, and in patients with metabolic disease. Consistently, DARS1 silencing/pharmacological inhibition reduced, while DARS1 overexpression increased, functional parameters of aggressiveness in vitro. In fact, xenograft and orthotopic tumors formed by DARS1-overexpressing cells had increased establishment capacity in vivo. Mechanistically, DARS1 protein levels were higher in nuclear, but not cytosolic, samples of HCC. An immunoprecipitation assay revealed 132 nuclear DARS1 interactors, three of the latter being members of the Spt-Ada-Gcn5 acetyltransferase (SAGA) complex, which regulates MYC acetylation and stability. This non-canonical interaction was confirmed by in silico docking of DARS1/SAGA crystal structures. Additionally, DARS1 modulation regulated MYC protein levels and phosphorylation, and the expression of MYC targets was reduced in RNA-seq data of DARS1-silenced liver cells. Consistently, DARS1 silencing reduced drug-induced senescence (Gemcitabine, Etoposide, Cisplatin), suggesting a link between DARS1-SAGA interaction and MYC-regulated senescence.

Conclusion: DARS1 is reduced in MASLD and overexpressed in HCC tissues and plasma samples, especially in metabolic disease patients. DARS1 could be implicated in the development of MASLD and its progression to HCC, wherein it could serve as biomarker or therapeutic target.Fundings: ISCIII (PI20/01301, PI23/00652; co-funded by the European Union), MINECO (FPU20/03957), JdA (PEMP-0036-2020, BIO-0139), FSEEN and CIBERobn/ehd.