Carnitine palmitoyltransferase-II inactivity promotes malignant progression of metabolic dysfunction-associated fatty liver disease via liver cancer stem cell activation

Abstract

Background: Metabolic dysfunction-associated fatty liver disease (MAFLD) is one of the main chronic liver diseases. However, the roles of mitochondrial carnitine palmitoyl transferase-II (CPT-II) downregulation and liver cancer stem cell (LCSC) activation remain to be identified.

Aim: To investigate the dynamic alterations in CPT-II inactivity and LCSC activation during the malignant progression of MAFLD.

Methods: Dynamic models of mouse MAFLD were generated via the consumption of a high-fat diet or the addition of 2-fluorenylacetamide for hepatocarcinogenesis. The mice were divided into groups on the basis of hematoxylin and eosin staining. Biochemistries, CPT-II, intrahepatic T cells, and LCSCs were determined and confirmed in clinical samples. The mitochondrial membrane potential (MMP) was analyzed. Differentially expressed genes were screened via RNA sequencing and enriched in KEGG pathways or GO functions.

Results: Dynamic models of MAFLD malignant transformation were successfully generated on the basis of pathological examination. Hepatic lipid accumulation was associated with the loss of mitochondrial CPT-II activity and alterations in the MMP, with decreases in liver CD3+ or CD4+ T cells and increased AFP levels. In the lipid accumulation microenvironment, mitochondrial CPT-II was inactivated, followed by aberrant activation of CD44+ or CD24+ LCSCs, as validated in MAFLD or hepatocellular carcinoma patient samples. In terms of mechanism, the biological process category focused mainly on the metabolic regulation of cells in response to external stimuli. The enriched molecular functions included protein binding, cell apoptosis, and cell proliferation.

Conclusion: CPT-II inactivity promotes the malignant progression of MAFLD via the loss of innate immune function and abnormal LCSC activation.

Keywords: Carnitine palmitoyl transferase-II; Liver cancer stem cells; Metabolic dysfunction-associated fatty liver disease; Mitochondria; T lymphocytes.