Ferroptosis

Core Biochemistry#

The Fenton Reaction and Lipid Peroxidation#

Excess labile (free, non-protein-bound) iron catalyzes Fenton reactions, generating hydroxyl radicals (OH.) from hydrogen peroxide:

> iron(II) (Fe2+) + H2O2 --> iron(III) + OH. + OH-

These hydroxyl radicals attack polyunsaturated fatty acids (PUFAs) in cell membranes, initiating self-propagating lipid peroxidation chain reactions. When membrane lipid peroxide accumulation exceeds the cell's capacity to repair or neutralize them, the membrane loses integrity and the cell dies.

GPX4: The Central Brake#

Glutathione peroxidase 4 (GPX4) is the primary enzyme that reduces lipid hydroperoxides to non-toxic lipid alcohols, using glutathione (GSH) as a cofactor.^{[3]Effects of Trace Elements on Endocrine Function and Pathogenesis of Thyroid Diseases — A Literature ReviewBrylinski L, Kostelecka K, Wolinski F et al. · 2025Open reference 3 ↓} GPX4 is a selenoprotein (requiring selenium for catalytic activity), which connects ferroptosis vulnerability to selenium status.^{[5]Recent advances in the application of metallomics in diagnosis and prognosis of human cancerYan Zhang, Jie He, Jiao Jin et al. · 2022Open reference 5 ↓}

Loss of GPX4 function—whether through genetic deletion, selenium deficiency, GSH depletion, or pharmacological inhibition—removes the brake on ferroptotic death and is a critical trigger in tubular cells in CKD, dopaminergic neurons in Parkinson's disease, and several cancers.^{[6]Molecular Mechanisms of Cellular Injury and Role of Toxic Heavy Metals in Chronic Kidney DiseaseManish Mishra, Larry Nichols, Aditi A. Dave et al. · 2022Open reference 6 ↓[2]Riederer 2021 — Iron as Concert Master in Parkinson's DiseaseRiederer P, Monoranu C, Strobel S et al. · 2021Open reference 2 ↓[3]Effects of Trace Elements on Endocrine Function and Pathogenesis of Thyroid Diseases — A Literature ReviewBrylinski L, Kostelecka K, Wolinski F et al. · 2025Open reference 3 ↓}

Iron Homeostasis and Ferroptosis Susceptibility#

The hepcidin-ferroportin axis is the master regulator of systemic iron levels. Key iron transport proteins include DMT1 (SLC11A2) for import and ferroportin (SLC40A1/FPN) for export, with hepcidin acting as a negative regulator. Iron regulatory proteins IRP1 and IRP2 sense cellular iron and adjust transferrin receptor and ferritin expression accordingly.

Disruption at any point in this regulatory network can tip cells toward iron overload and ferroptotic vulnerability.

Ferroptosis in Parkinson's Disease#

The connection between iron, ferroptosis, and Parkinson's disease (PD) represents one of the most developed threads in the metal toxicology literature.

Substantia Nigra Iron Accumulation#

Iron accumulation in the substantia nigra (SN) is a hallmark of PD—iron acts as the "concert master" coordinating age-dependent accumulation beyond normal aging.^{[2]Riederer 2021 — Iron as Concert Master in Parkinson's DiseaseRiederer P, Monoranu C, Strobel S et al. · 2021Open reference 2 ↓}

Dopaminergic neurons in the SN are uniquely vulnerable because they contain neuromelanin—a mixed polymer of eumelanin and pheomelanin components that normally sequesters redox-active iron.^{[7]Pheomelanin, Eumelanin, and Neuromelanin: A Metal-Linked Hypothesis for Parkinson's Risk in RedheadsEyer K, Karen Pendergrass · 2025Open reference 7 ↓}

When neuromelanin's iron-binding capacity is exceeded or compromised, free iron catalyzes lipid peroxidation and ferroptotic cell death.^{[2]Riederer 2021 — Iron as Concert Master in Parkinson's DiseaseRiederer P, Monoranu C, Strobel S et al. · 2021Open reference 2 ↓[1]Microbial Metallomics and Parkinson's Disease: A Unified Metal-Driven Framework Linking Ferroptosis, Dysbiosis, and alpha-Synuclein PathologyKaren Pendergrass · 2025Open reference 1 ↓}

The Neuromelanin-Metal Hypothesis#

The pheomelanin-eumelanin ratio in neuromelanin may modulate ferroptotic vulnerability. Eumelanin contains catechol and carboxyl groups enabling strong chelation of iron(III) (Fe3+) and copper(II) (Cu2+), whereas pheomelanin's benzothiazine units bind metals less effectively and can themselves catalyze pro-oxidant reactions.

Individuals with MC1R loss-of-function variants (e.g., redheads) produce more pheomelanin, potentially reducing neuromelanin iron-chelation capacity in the SN and increasing the labile iron pool available to drive ferroptosis. Epidemiological data show approximately 50-100% increased PD risk in individuals with red hair phenotypes.

The Gut-Brain Ferroptosis Axis#

The Pendergrass framework proposes ferroptosis as the convergent cell death mechanism linking peripheral gut pathology to central dopaminergic neuron loss in PD:

1. Dietary/environmental Heavy Metals (iron (Fe), manganese (Mn), nickel (Ni)) reshape gut microbial communities, favoring metal-tolerant pathogens over SCFA-producing commensals
2. Loss of gut barrier integrity permits bacterial translocation and systemic Metal-Driven Inflammation
3. Alpha-synuclein aggregation in the enteric nervous system may be triggered by metal-induced Oxidative Stress
4. Ferroptosis drives both gut epithelial damage and dopaminergic neuron death

PD patients consistently show reduced Prevotellaceae, Lachnospiraceae, and Faecalibacterium with increased Enterobacteriaceae—a pattern consistent with metal-driven Dysbiosis.

Ferroptosis in Cancer#

Ferroptosis has emerged as a therapeutic target in oncology. Cancer cells with disrupted iron homeostasis or elevated iron requirements may be selectively vulnerable to ferroptosis induction. Platinum-based chemotherapy (cisplatin, carboplatin) relies partly on ferroptotic cell death, and platinum resistance converges on ferroptosis evasion via the Keap1-Nrf2-GPX4 axis.

Thyroid Cancer#

GPX4 has been identified as a ferroptosis regulator in thyroid cancer. Additionally, cuproptosis (copper-dependent cell death via FDX1) represents a parallel metal-dependent death pathway in thyroid malignancies. The disulfiram/copper (Cu) complex inhibits cancer stem cell activity in thyroid cancer, suggesting therapeutic potential for metal-dependent death induction.

Ferroptosis in Kidney Disease#

In chronic kidney disease (CKD), iron-dependent phospholipid peroxidation in renal tubular cells represents a key pathological mechanism.^{[6]Molecular Mechanisms of Cellular Injury and Role of Toxic Heavy Metals in Chronic Kidney DiseaseManish Mishra, Larry Nichols, Aditi A. Dave et al. · 2022Open reference 6 ↓} GPX4 loss of function is a critical trigger, and iron-restricted diet has shown protective effects in animal models.^{[6]Molecular Mechanisms of Cellular Injury and Role of Toxic Heavy Metals in Chronic Kidney DiseaseManish Mishra, Larry Nichols, Aditi A. Dave et al. · 2022Open reference 6 ↓}

As CKD progresses and GFR decreases, the ability to eliminate environmental toxicants declines, creating a vicious cycle of metal accumulation, further ferroptotic injury, and progressive kidney damage.^{[6]Molecular Mechanisms of Cellular Injury and Role of Toxic Heavy Metals in Chronic Kidney DiseaseManish Mishra, Larry Nichols, Aditi A. Dave et al. · 2022Open reference 6 ↓}

Ferroptosis in Gut Pathology#

Iron homeostasis in the intestinal epithelium directly influences ferroptotic susceptibility. Iron excess in the gut lumen—whether from dietary sources, supplementation, or impaired regulation—can drive ferroptotic damage to epithelial cells, compromising barrier integrity.

This connects to the broader gut-metal-microbiome relationship: iron deficiency reduces commensal beneficial bacteria (Lactobacillus) while iron excess increases harmful bacteria (Bacteroides, E. coli), and both extremes can contribute to epithelial vulnerability.