Carcinome hépatocellulaire compliquant la MASLD : analyse métabolomique, lipidomique et d'expression génique du foie tumoral et non tumoral

Hepatocellular carcinoma (HCC) is a complex liver disease that can occur in viral or alcohol-induced chronic liver disease, as well as in metabolic dysfunction associated steatotic liver disease (MASLD), which affects 25% of the global population and is increasing in incidence. Although HCC usually complicates liver cirrhosis, 25-30% of MASLD-HCC patients show no or mild fibrosis, suggesting that different carcinogenic mechanisms are involved in MASLD-HCC. Therefore, research on this issue is needed to identify different biomarkers that could potentially be used for non-invasive diagnostic or screening purposes. Thus, our work focused on the metabolomic, lipidomic and gene expression analyses between the two groups of MASLD-HCC stratified by fibrosis severity, aiming to explore the mechanisms of carcinogenesis and to identify biomarkers.Tumor (TT) and non-tumor (NTT) extract tissue samples of 52 MASLD-HCC patients (F0F1-F2=26, F3F4=26) were selected. Liquid chromatography-high resolution mass spectrometry (LC-HRMS/MS) was used for metabolomic and lipidomic analyses. By comparing TT with NTT, differentially changed metabolites and lipids were identified in both groups of MASLD-HCC. Based on these metabolomic and lipidomic features, 33 genes involved in de Novo lipogenesis (DNL), fatty acid oxidation (FAO) and cholesterol ester (CE), triglyceride (TG), sphingolipid (SP) and glycerophospholipid (GP) metabolism pathways were selected for gene expression analysis by real-time quantitative PCR (RT-qPCR). The cohort was expanded and healthy liver tissues (HL) were obtained to serve as controls.Metabolomic and lipidomic analyses revealed that MASLD-HCC-F0F1-F2 shown acylcarnitine and lipid accumulation, including long-chain acylcarnitine (LCAC), sphingomyelin (SM), and GP, while TG, CE, and ceramide (Cer) levels decreased. In contrast, MASLD-HCC-F3F4 shown a distinct anabolic feature, with short-chain acylcarnitine (SCAC), SP, GP, TG, and CE levels decreased, while medium-chain acylcarnitine and LCAC levels increased.Gene expression analysis shown that among 33 genes, no genes were specifically regulated in MASLD-HCC-F3F4, while the expression of 6 genes ACAT2, DGAT2, ACOX1, CHKA, PLD1, and PLD2 was exclusively up-regulated in MASLD-HCC-F0F1-F2.Combined the current and previous data, we propose that according to fibrosis level, MASLD-HCC exhibits 2 different lipid metabolic phenotypes. MASLD-HCC-F0F1-F2 exhibited a cholinergic phenotype, while MASLD-HCC-F3F4 is characterized by methylation disorders.In addition, despite the RT-qPCR shown that 15 genes involved in DNL and FAO pathways were up-regulated in both groups of MASLD-HCC, the simultaneous up-regulation of the genes involved in these two pathways challenged the conventional dogma that DNL and FAO cannot be activated simultaneously, a notion supported by several published studies on VIRUS-HCC. This raises the hypothesis that this dogma may reflect differences in the underlying etiology of HCC (MASLD vs. VIRUS). To test this hypothesis, these 15 genes related to DNL and FAO were analyzed in 161 VIRUS-HCC patients and 98 MASLD-HCC patients.The results demonstrated that VIRUS-HCC displayed an up-regulation of DNL-related genes, while the FAO-related genes were down-regulated, which aligned with other published studies. However, in MASLD-HCC, both DNL- and FAO-related genes were up-regulated. This observation highlighted a new paradigm for MASLD-HCC, where DNL and FAO pathways can be simultaneously activated. Furthermore, cell experiments confirmed this new paradigm.In conclusion, our study underlined 3 major findings: 1) Two distinct metabolic phenotypes of MASLD-HCC stratified by liver fibrosis levels were identified. 2) CHKA and PLD could be considered as biomarkers of MASLD-HCC-F0F1-F2. 3) The new paradigm: simultaneous activation of FAO and DNL, may be considered as a hallmark of MASLD-HCC.