Ferroptosis, a distinctive form of programmed cell death first identified in 2012, is rapidly emerging as a promising therapeutic target in cancer treatment. This iron-dependent cell death mechanism, characterized by lipid peroxidation and accumulation of reactive oxygen species, offers new avenues for overcoming drug resistance and immune escape in various malignancies.
Core Mechanisms Drive Therapeutic Potential
The ferroptosis pathway operates through several interconnected mechanisms that distinguish it from other forms of cell death. The GPX4 pathway serves as the central regulatory hub, where glutathione peroxidase 4 catalyzes the reduction of lipid hydroperoxides to benign lipid alcohols. When GPX4 function is compromised through glutathione depletion or direct inhibition, toxic lipid peroxides accumulate, triggering ferroptosis.
Research has demonstrated that the FSP1-CoQ10 pathway provides an alternative regulatory mechanism. FSP1 functions as an oxidoreductase of coenzyme Q10, and its N-terminal myristoylation targets it to the plasma membrane where it mediates NADH-dependent CoQ10 reduction, subsequently suppressing lipid peroxidation and inhibiting ferroptosis.
Iron metabolism plays a crucial role in ferroptosis regulation. The majority of intracellular iron is stored in ferritin complexes, while a small fraction exists as labile iron pools that promote ROS accumulation through the Fenton reaction. Iron regulatory proteins IRP-1 and IRP-2 control the expression of transferrin and transferrin receptor 1, influencing iron transport and cellular susceptibility to ferroptosis.
Lipid Metabolism Controls Cell Death Sensitivity
Polyunsaturated fatty acids, particularly arachidonic acid and adrenic acid, serve as key substrates for lipid peroxidation in ferroptosis. Acyl-CoA synthetase long-chain family member 4 (ACSL4) catalyzes the linking of coenzyme A to long-chain PUFAs, while lysophosphatidylcholine acyltransferase 3 (LPCAT3) incorporates these fatty acids into membrane phospholipids.
Studies have shown that genetic knockout of ACSL4 markedly inhibits ferroptosis induction, while overexpression increases cellular sensitivity. Lipoxygenases can directly oxidize PUFAs in cellular membranes, and their inhibition effectively blocks ferroptosis progression. The cytochrome P450 oxidoreductase system also contributes to lipid peroxidation initiation through electron transfer mechanisms.
Immune System Interactions Enhance Therapeutic Efficacy
The relationship between ferroptosis and immune function has revealed significant therapeutic opportunities. CD8+ T cells play a pivotal role in inducing ferroptosis in tumor cells during immunotherapy. Interferon-gamma released from activated CD8+ T cells downregulates SLC3A2 and SLC7A11 expression on tumor cell surfaces, suppressing cystine uptake and promoting lipid peroxidation.
Conversely, CD36-mediated ferroptosis in tumor-infiltrating CD8+ T cells can impair their cytotoxic function, creating a complex regulatory network. GPX4-deficient T cells rapidly accumulate membrane lipid peroxides and undergo ferroptosis, while the selenium-GPX4 axis protects follicular helper T cells from ferroptosis damage.
Macrophage polarization is closely linked to iron homeostasis and ferroptosis regulation. Iron overload drives macrophage polarization toward the M1 phenotype through elevated ROS production and upregulated p53 protein acetylation. M1-type macrophages can initiate Fenton reaction-mediated ferroptosis, showing synergistic activity with PD-1 antibodies and TGF-β inhibitors.
Clinical Applications Show Promise
Several clinically approved drugs have demonstrated ferroptosis-inducing capabilities. Sorafenib, lorazepam, and artemisinin exert anti-tumor effects by inducing ferroptosis in cancer cells. Erastin, glutamic acid, and sulfasalazine achieve ferroptosis induction through specific inhibition of the System Xc- transporter, while RSL3, ML162, FIN56, and FINO2 directly target the GPX4 protein.
Novel nanomedicines are being developed to enhance ferroptosis-based therapy. Ultrasmall single-crystal iron nanoparticles efficiently induce tumor cell ferroptosis while promoting dendritic cell maturation and triggering adaptive T cell responses. When combined with PD-L1 immune checkpoint blockade, these nanoparticles significantly potentiate immune responses and foster robust immunological memory.
Engineered exosome-like nanovesicles loaded with ferroptosis inducers can effectively decrease immunosuppressive cell populations within the tumor microenvironment, including M2-like tumor-associated macrophages, myeloid-derived suppressor cells, and regulatory T cells, thereby promoting tumor ferroptosis.
Thyroid Cancer Applications Demonstrate Specificity
In thyroid cancer, ferroptosis-related genes show differential expression patterns compared to normal tissues. GPX4 expression is elevated in thyroid cancer tissues and correlates with poor prognosis, while GPX4 knockdown triggers ferroptosis and inhibits proliferation of thyroid cancer cells.
The cystine/glutamate antiporter component SLC7A11 is dramatically overexpressed in papillary thyroid cancer tissues. Research has shown that fat mass and obesity-associated protein (FTO) suppresses thyroid cancer development by downregulating SLC7A11 expression and inducing ferroptosis. Similarly, ETV4 transcription factor knockdown inhibits thyroid cancer growth through SLC7A11 downregulation.
Therapeutic agents show promising results in thyroid cancer models. RSL3, a direct GPX4 inhibitor, significantly activates ferroptosis and suppresses thyroid cancer cell survival. Vitamin C at pharmacological concentrations induces ferroptosis in anaplastic thyroid cancer cells through GPX4 inactivation and iron accumulation. Natural compounds like neferine and curcumin demonstrate ferroptosis-inducing and anti-tumor effects through various signaling pathways.
Future Directions and Challenges
Despite promising preclinical results, several challenges remain for clinical translation of ferroptosis-based therapies. The complexity of ferroptosis regulation across different cancer types requires personalized approaches. Normal tissue toxicity represents a significant concern, necessitating the development of targeted delivery systems.
Combination strategies integrating ferroptosis inducers with conventional therapies show particular promise. The synergistic effects between ferroptosis and immunotherapy suggest that dual-targeting approaches may overcome current limitations in cancer treatment. However, comprehensive clinical studies are essential to evaluate safety and efficacy profiles.
The identification of predictive biomarkers for ferroptosis sensitivity will be crucial for patient selection. Ferroptosis-related gene signatures and metabolic profiles may serve as valuable tools for treatment stratification. Additionally, understanding the temporal dynamics of ferroptosis induction and its interaction with other cell death pathways will inform optimal dosing and scheduling strategies.
As research continues to elucidate the molecular mechanisms underlying ferroptosis, this novel form of cell death represents a paradigm shift in cancer therapy, offering hope for patients with treatment-resistant malignancies and opening new avenues for precision medicine approaches.
