FDX1 Downregulation Activates Mitophagy and the PI3K/AKT Signaling Pathway to Promote Hepatocellular Carcinoma Progression by Inducing ROS Production

Background Mitochondrial dysfunction and metabolic reprogramming can lead to the development and progression of hepatocellular carcinoma (HCC). Ferredoxin 1 (FDX1) is a small mitochondrial protein and recent studies have shown that FDX1 plays an important role in tumor cuproptosis, but its role in HCC is still elusive. In this study, we aim to investigate the expression and novel functions of FDX1 in HCC. Methods FDX1 expression was first analyzed in publicly available datasets and verified by immunohistochemistry, qRT-PCR and Western blot. In vitro and in vivo experiments were applied to explore the functions of FDX1. Non-targeted metabolomics and RNA-sequencing were used to determine molecular mechanism. mRFP-GFP-LC3 lentivirus transfection, Mito-Tracker Red and Lyso-Tracker Green staining, transmission electron microscopy, flow cytometry, JC-1 staining, etc. were used to analyze mitophagy or ROS levels. Hydrodynamic tail vein injection (HTVi) and patient-derived organoid (PDO) models were used to analyze effect of FDX1 overexpression. Results FDX1 expression is significantly downregulated in HCC tissues. FDX1 downregulation promotes HCC cell proliferation, invasion in vitro and growth, metastasis in vivo. In addition, FDX1 affects metabolism of HCC cells and is associated with autophagy. We then confirmed that FDX1 deficiency increases ROS levels, activates mitophagy and the PI3K/AKT signaling pathway in HCC cells. Interestingly, scavenging ROS attenuates the tumor-promoting role and mitophagy of FDX1 downregulation. The results of HTVi and PDO models both find that FDX1 elevation significantly inhibits HCC progression. Moreover, low FDX1 expression is associated with shorter survival and is an independent risk factor for prognosis in HCC patients. Conclusions Our research had investigated novel functions of FDX1 in HCC. Downregulation of FDX1 contributes to metabolic reprogramming and leads to ROS-mediated activation of mitophagy and the PI3K/AKT signaling pathway. FDX1 is a potential prognostic biomarker and increasing FDX1 expression may be a potential therapeutic approach to inhibit HCC progression.

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