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Aims: Emodin, a natural anthraquinone, exerts antitumor effects by increasing reactive oxygen species (ROS) and inducing apoptosis, autophagy, and cell-cycle arrest. However, its potential to induce ferroptosis, a distinct iron-dependent cell death, in hepatocellular carcinoma (HCC) remains unexplored.
Materials and methods: The anti-proliferative effect of Emodin was assessed in human HCC cell lines HepG2 and MHCC97H. Ferroptosis was evaluated following treatment with 40 μM Emodin for 24 h, measuring ROS, lipid peroxidation, glutathione levels, and mitochondrial morphology. Molecular mechanisms were investigated via reverse transcription polymerase chain reaction (RT-qPCR), western blot, and functional rescue experiments. A HepG2 xenograft model (25 and 50 mg/kg Emodin, intraperitoneal.) and immunohistochemistry were used to confirm the findings in vivo.
Key findings: Emodin inhibited HCC cell proliferation and induced ferroptosis, characterized by ROS accumulation, lipid peroxidation, and reduced glutathione levels, mitochondrial membrane potential, and glutathione peroxidase 4 (GPX4) expression. Mechanistically, Emodin upregulated microRNA-4465 (miR-4465), which directly targeted and suppressed the NFE2 like bZIP transcription factor 3 (NFE2L3). This led to inhibition of the NFE2L3/3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMGCR)/GPX4 signaling axis. Overexpression of NFE2L3 rescued cells from Emodin-induced ferroptosis. In the xenograft model, Emodin significantly suppressed tumor growth and downregulated the NFE2L3/HMGCR/GPX4 pathway in tumor tissues.
Significance: Our study demonstrates that Emodin induces ferroptosis through the miR-4465/NFE2L3/HMGCR/GPX4 axis in HCC, revealing NFE2L3's role in ferroptosis and suggesting Emodin as a promising therapeutic candidate.