Cell Death by Iron and Copper in Cancer and Brain Diseases: How Iron and Copper Removing Agents May Influence It

Bimetallic nanoplatforms integrate both Fe and Cu ions—the key initiators of ferroptosis and cuproptosis—into a single carrier, thereby maximizing the synergistic effect against malignant cells [34,45]. Examples include copper/iron hybrid hollow amorphous MOFs (HaMOF) [33], copper/iron bimetal gallic acid (CuFeGA) and metal-phenolic networks (MPNs) [52], and copper-doped hollow Prussian blue (PB) nanozymes [34]. These systems are designed to amplify cellular oxidative stress and disrupt metal metabolism simultaneously [33]. The integrated mechanism of nanomaterial-mediated dual RCD induction, characterized by the concurrent depletion of GSH and the trapping of metal ions to amplify both ferroptosis and cuproptosis, is illustrated in Figure 4.

i. Ferroptosis pathway: Bimetallic frameworks primarily enhance ferroptosis by disrupting the cellular antioxidant defense system and boosting the production of lethal reactive oxygen species (ROS) [34]. The initial step often involves the Fe and Cu ions acting as dual GSH depletors. For example, CuFeGA MPNs rely on two procedures of GSH consumption, releasing oxidized metal ions (Fe³⁺ and Cu²⁺), which are then rapidly reduced by GSH (consuming the GSH and generating Fe²⁺ and Cu⁺) to initiate the first phase of GSH depletion. Subsequently, the released Gallic acid (GA) further consumes the residual GSH. This robust GSH depletion subsequently inactivates the master ferroptosis regulator, GPX4, preventing it from converting toxic LOOH into harmless LOH. Concurrently, the released Fe²⁺ and Cu⁺ catalyze Fenton and Fenton-like reactions, reacting with endogenous hydrogen peroxide (H₂O₂) to generate highly toxic hydroxyl radicals. This surge in ROS and consequent oxidative stress leads to the accumulation of LOOH, ultimately initiating augmented ferroptosis [34,52,53]. Furthermore, some nano-systems like the HaMOF induce metabolic disorders that specifically downregulate the copper transporter ATP7A and contribute to high iron retention, which supports the Fenton reaction and enduring ferroptosis [33].

ii. Cuproptosis pathway: Cuproptosis induction via bimetallic nanoplatforms relies heavily on accumulating sufficient intracellular Cu⁺ and circumventing the protective effects of GSH. The initial release of Cu⁺ (and its generation via the reduction of Cu²⁺) is critical for inducing cuproptosis. This accumulation of excessive Cu⁺ in the resulting GSH-depleted environment causes the aggregation of lipoylated proteins, notably DLAT. The aggregation of DLAT interferes with the mitochondrial Krebs cycle and leads to the loss of iron-sulfur (Fe-S) cluster proteins, culminating in proteotoxic stress and cuproptosis [34,52]. Mechanistically, the synergistic effect often relies on feedback loops: HaMOF treatment causes mitochondrial damage and subsequently disrupts adenosine triphosphate (ATP) production. This reduction in cellular energy suppresses the expression of copper exporters, such as ATP7A, thereby enhancing copper ion retention in the cytoplasm and further promoting cuproptosis [33,44].

Targeted strategies employ sophisticated carriers to deliver metal ions or small molecules capable of disrupting cellular copper homeostasis, often specifically inhibiting efflux pathways. One strategy involves CRISPR-Cas9 ribonucleoprotein (RNP) nanocarriers, specifically the RNP@Cu₂O@SPF platform, which utilizes a silica-polydopamine-folic acid (SPF) shell to facilitate targeted delivery [46]. These nanoconstructs are engineered to transport the RNP complex—comprising the Cas9 endonuclease and a single-guide RNA targeting the ATP7A gene (sgATP7A)—to achieve the site-specific gene silencing of the copper transporter ATP7A [46,54]. The degradation of the nanocarrier in the GSH-rich, weak acidic tumor environment releases RNP and Cu⁺ ions. By inhibiting ATP7A, this system ensures sustained high copper levels in the cytoplasmic fluid, which subsequently enhances the efficacy of cuproptosis, ferroptosis, and associated chemodynamic therapy (CDT) [18,46].

A similar concept is implemented using the CussOMEp nanozyme system, which integrates a copper-based nanovector with the copper-transporter inhibitor omeprazole. In this architecture, omeprazole serves to selectively block the ATP7A exporter, driving significant intracellular Cu²⁺ accumulation and escalating oxidative stress. This copper overload promotes the oligomerization of DLAT proteins, a critical step in the induction of cuproptosis. Furthermore, the copper-based nanovector itself exhibits multi-enzymatic mimicry—including peroxidase, catalase, and glutathione peroxidase-like activities—enabling the catalytic conversion of H₂O₂ into hydroxyl radicals and oxygen. Simultaneously, the platform depletes intracellular GSH, creating a metabolic environment that robustly synergizes cuproptosis with enhanced ferroptosis [55,56].

Furthermore, carrier-free metal-polyphenolic nanocomplexes (T-T@Cu) utilize tannic acid for mitochondrial targeting. This nanoplatform can induce mild photothermal-boosted ferroptosis, which results in decreased cellular ATP levels. This energy depletion subsequently downregulates the expression and activity of copper efflux proteins (ATP7A/7B), thereby disrupting copper homeostasis and significantly exacerbating cuproptosis in tumor cells [57].

The efficacy of anti-cancer treatments has been profoundly augmented by strategies exploiting the intricate crosstalk between distinct forms of RCD, particularly the iron-dependent ferroptosis and the copper-dependent cuproptosis. This synergistic potential is frequently realized through the deployment of specialized small molecules and nanoplatforms designed to disrupt metal homeostasis and cellular redox balance concurrently [31,33,34,44]. A central nexus in this synergy is the cellular antioxidant GSH, which acts as a co-inhibitor for both ferroptosis (via the GPX4 pathway) and cuproptosis (by chelating copper ions). Consequently, inducing a state of dual GSH depletion is an established strategy to sensitize tumor cells to both pathways [34,44,52].

Nanoplatforms are engineered specifically to exploit these shared metabolic vulnerabilities. For instance, CuFeGA MPNs enable a phased depletion of GSH: upon exposure to the high-GSH TME, the networks dissociate to release GA, Fe²⁺, and Cu⁺, followed by secondary GSH consumption mediated by the released GA. The resulting surge in bimetallic ions drives intense oxidative stress via Fenton and Fenton-like reactions, precipitating LPO and the downregulation of GPX4 to trigger ferroptosis. Simultaneously, the elevated Cu⁺ levels induce the oligomerization of lipoylated DLAT, thereby activating the cuproptosis pathway [52]. A similar synergistic effect is achieved using bimetallic Fe-Cu MOFs, which utilize the coordinated action of iron and copper to escalate cellular damage beyond the thresholds achievable by single-agent therapies. This dual-metal strategy ensures that the induction of ferroptosis and cuproptosis is mutually reinforcing, effectively overcoming the robust antioxidant defenses typical of malignant cells [31].

Beyond direct metal delivery, small molecules targeting fundamental metabolic regulators can achieve potent synergistic anti-cancer effects. Ferroptosis inducers, such as sorafenib and erastin, significantly potentiate copper ionophore-induced cuproptosis in hepatocellular carcinoma cells. This synergy is driven by two complementary mechanisms: first, these inducers deplete the intracellular GSH pool by inhibiting the cystine/glutamate antiporter (System xc−). Second, they augment the cuproptosis pathway by stabilizing FDX1 through the suppression of mitochondrial matrix-related proteases, thereby preserving the protein lipoylation essential for copper-induced cell death [58,59].

Furthermore, nanotherapeutic strategies specifically designed to overcome copper efflux mechanisms have been developed. Elesclomol, a copper chelator, induces copper overload and subsequent ferroptosis in colorectal cancer (CRC) cells by promoting the ubiquitin-mediated degradation of the copper efflux transporter ATP7A, leading to copper retention in mitochondria and subsequent ROS accumulation [60]. In a similar vein, the mild photothermal-boosted ferroptosis approach (T−T@Cu), a carrier-free metal-polyphenolic nanocomplex based on tannic acid and copper, exploits the resultant depletion of cellular ATP to disrupt the function and expression of copper efflux proteins, such as ATP7A/7B, thereby maintaining high intracellular Cu levels necessary for robust cuproptosis induction [44,57].

Importantly, this synergy represents a causal hierarchy rather than mere metabolic co-occurrence. Initial iron-driven lipid peroxidation inflicts catastrophic mitochondrial damage that depletes intracellular ATP stores. Because the primary copper exporters (ATP7A/B) are P-type ATPases, this bioenergetic “power outage” effectively locks copper within the cytosol, transforming a sublethal copper load into a toxic trigger for secondary cuproptosis via DLAT aggregation [19]. In this contingent cascade, ferroptosis acts as the metabolic initiator that disables the cell’s ability to clear the copper load, while copper-mediated glutathione depletion simultaneously lowers the kinetic barrier for ferroptotic propagation. This mutually reinforcing feedback loop ensures that the activation of one pathway creates the obligatory metabolic prerequisites for the other [3,5], circumventing the redundant antioxidant defenses typical of resistant malignancies. These findings underscore the mutually reinforcing therapeutic relationship, where copper and iron homeostasis disruption pathways are utilized to amplify ROS-driven cellular destruction [34,44].

The overarching principles of these metal-centric interventions are summarized in Figure 5, which illustrates the targeted modulation of metal homeostasis: strategies for killing via Fe/Cu accumulation in cancer versus strategies for protection via Fe chelation and ROS neutralization in other pathological states.

Ferroptosis, defined as an iron-dependent form of cell death driven by LOOH accumulation, can be specifically manipulated using various small molecules and engineered nanoplatforms that regulate iron availability and mitigate oxidative stress. Targeting iron metabolism directly through chelation remains the foundational strategy for preventing ferroptosis [26,36,39]. Traditional iron chelators like DFO are highly effective at blocking ferroptosis. The clinical relevance of this approach is validated by studies showing that the orally available chelator DFP decreased iron content in the substantia nigra of PD patients, which is associated with slower disease progression [38,39]. Extending this strategy, the small molecule SK4 was rationally designed to incorporate structural elements facilitating translocation across the BBB via the LAT1 transporter. Detailed physicochemical analysis confirmed that SK4 exhibited a stronger complex formation affinity toward Fe³⁺ than DFP, especially within the higher pH milieu characteristic of mitochondria, providing superior protection against Fe²⁺ and MPP⁺ (1-methyl-4-phenylpyridinium)-induced neurodegeneration [38]. Furthermore, the peptide thymosin β4 has been identified as an endogenous iron chelator capable of binding both Fe²⁺ and Fe³⁺ ions in four distinct regions of the peptide, consequently inhibiting erastin- and glutamate-induced ferroptosis [35].

Alternatively, ferroptosis can be averted through radical scavenging that halts LPO. Potent inhibitors like Ferrostatin-1 (Fer-1) and Liproxstatin-1 (Lip-1) function as radical trapping antioxidants (RTAs) [36]. Research into metal complexes identified that the copper complex Cu^II(atsm), currently in clinical trials for neurodegenerative diseases, prevents ferroptotic cell death in neuronal models with a potency comparable to Lip-1. This antiferroptotic activity is attributed to its function as a lipid RTA, quenching lipid peroxyl radicals without modulating the oxidation state of iron species. Intriguingly, the analogous nickel complex Ni^II(atsm) showed comparable protective effects, suggesting that the underlying mechanism lies primarily in the delocalized conjugated conformation of the ligand rather than merely the copper ion itself [30].

Ferroptosis is also modulated by non-iron metals. Studies have demonstrated that zinc significantly affects ferroptosis sensitivity: while zinc chelators confer resistance, the addition of exogenous ZnCl₂ promotes cell death, even counteracting the protective effect of the iron chelator DFO. This process is regulated by the ZIP7 transporter, which facilitates the release of Zn²⁺ from the endoplasmic reticulum into the cytosol—a flux essential for maintaining organelle homeostasis and modulating ferroptotic pathways [61]. This is exemplified by ZnO nanoparticles, which utilize ion-leaking properties to disrupt intracellular iron uptake and storage mechanisms. This zinc-mediated disruption triggers a p53-dependent downregulation of GPX4 and GSH depletion, proving that exogenous iron is not a prerequisite for ferroptotic induction if endogenous metal homeostasis is sufficiently destabilized [62].

Finally, nanomaterials offer diverse pathways to inhibit ferroptosis. Carbon dot nanozymes protect cells by chelating Fe²⁺ via surface functional groups (carbonyl, hydroxyl, carboxyl) to inhibit the Fenton reaction, while simultaneously scavenging highly ROS [63]. Similarly, polydopamine (PDA) NPs mitigate intervertebral disc degeneration (IVDD)-associated ferroptosis through three distinct mechanisms: ROS scavenging, Fe²⁺ chelation, and, notably, suppression of the ubiquitin-mediated degradation of the anti-ferroptotic enzyme GPX4 [64].

The fundamental research into small-molecule and nano-mediated regulation of ferroptosis and cuproptosis pathways has translated into promising therapeutic strategies across oncology, neurodegeneration, and acute tissue injury.

In oncology, the focus is largely on utilizing the intrinsic synergy between Fe and Cu pathways to enhance tumor cell destruction and augment immune response activation. An actively targeted magneto-liposome (T-LMD), co-encapsulated with oleic acid-coated iron oxide NPs and doxorubicin, demonstrated superior anti-tumor efficacy in human triple negative breast carcinoma (TNBC) cells, primarily by activating ferroptosis through enhanced LPO and ROS generation [65]. Moreover, advanced combination nanotherapies leveraging metal-mediated cell death pathways significantly potentiate immunotherapy. For instance, core–shell nanoparticles combining copper and erastin strongly inhibits tumor growth in murine colon and breast cancer studies. When coupled with immune checkpoint blockade (ICB), the combination therapy effectively synergized T cell proliferation and reinvigoration, leading to potent tumor regression and prevention of metastasis by inducing robust immunogenic cell death [37,66]. This strategy is further validated by the development of bimetallic Fe-Cu MOFs, which have demonstrated the ability to effectively eliminate solid tumors and significantly extend survival in tumor-bearing mice through the co-activation of cuproptosis and ferroptosis [31]. Similarly, specialized copper-based nanozymes (such as CussOMEp), engineered to enhance intracellular Cu²⁺ accumulation and synergize Fe/Cu pathways, have shown potent inhibition of tumor metastasis when integrated with targeted immunotherapy [55].

In neurodegenerative disorders, high iron deposition in the CNS is a characteristic finding in conditions like PD, making iron-dependent ferroptosis a promising therapeutic target [26,36,38]. The specialized iron chelator SK4, capable of penetrating the BBB, provided robust neuroprotection in experimental models of PD by mitigating MPP⁺ and Fe²⁺-induced toxicity [38]. The iron chelator DFO and the ferroptosis inhibitor Lip-1 also successfully reduced intracellular oxidative stress and protected dopaminergic neurons in vitro from MPP⁺ damage [39]. In addition, the complex Cu^II(atsm) is currently being investigated in clinical trials for ALS and PD due to its potent, brain-penetrant antiferroptotic activity, acting as a lipid RTA [30].

Ferroptosis is also implicated in acute tissue damage such as hepatic ischemia–reperfusion (I/R) injury, where donor iron overload is identified as an independent risk factor for liver damage following liver transplantation. In murine models, I/R injury induced LPO and hallmark ferroptotic signaling, effects that were significantly attenuated by the specific ferroptosis inhibitor Fer-1 or the iron chelator DFO. Iron overload specifically exacerbated I/R injury, confirming ferroptosis involvement [67]. Inhibiting ferroptosis with Fer-1 also suppressed subsequent inflammatory responses, suggesting that ferroptosis is an upstream trigger for necroinflammation in hepatic I/R injury [68]. Beyond liver injury, carbon dot nanozymes have demonstrated success in alleviating renal I/R injury by chelating Fe²⁺ and scavenging ROS to prevent ferroptosis [63]. Similarly, PDA NPs efficiently mitigated IVDD in rats by directly targeting ferroptosis pathways, including inhibiting GPX4 ubiquitination and reducing iron accumulation, thereby offering a novel therapeutic strategy for musculoskeletal disorders [64].

The fundamental approach to blocking ferroptosis relies on the application of iron chelators, notably DFO. DFO inhibits ferroptosis and associated neurodegeneration in various preclinical systems by sequestering excess iron, thereby mitigating iron-induced oxidative damage and preventing the initiation of the Fenton reaction [36,38,39,72].

In the Parkinsonian paradigm, the neurotoxicant MPP⁺, a common mimetic used to induce dopaminergic neuronal toxicity [73,74], triggers ferroptosis characterized by mitochondrial shrinkage and a marked reduction in the expression of the essential anti-ferroptotic protein GPX4. Treatment with the iron chelator DFO effectively protects these neurons in vitro by reducing intracellular oxidative stress and rescuing mitochondrial function, while simultaneously upregulating GPX4 and ferritin heavy-chain expression, indicating that DFO specifically inhibits the ferroptosis signaling pathway activated by MPP⁺ injury. Furthermore, DFO has demonstrated neuroprotective effects comparable to the canonical ferroptosis inhibitor Lip-1, suggesting that its efficacy stems primarily from the sequestration of the intracellular free ferrous iron pool, the primary driver of lipid radical generation [39].

In studies of chronic neurodegeneration, clinical trials assessing the orally available iron chelator DFP have shown varied but promising results in PD patients [75,76], with early-stage patients exhibiting decreased substantia nigra iron content and slowed disease progression associated with improved motor scores [38]. In mice subjected to chronic METH exposure, DFP effectively alleviated nigrostriatal iron deposition, LPO, and dopaminergic cell death, directly mitigating ferroptosis induced by chronic METH exposure. DFP treatment also attenuated the reduction in GPX4 expression, stabilizing the cell’s endogenous defense against oxidative damage. Importantly, DFP selectively reduced iron levels without influencing copper, zinc, manganese, or magnesium concentrations in the substantia nigra, suggesting a specific binding preference for iron at the tested concentrations [26,77].

Beyond conventional iron chelators, advanced strategies focus on engineering small molecules capable of efficiently crossing the BBB and selectively targeting neuronal vulnerability [36,38].

The hydroxypyridinone-based molecule SK4 exemplifies this design rationale, formulated to leverage the ubiquitous LAT1 for enhanced CNS penetration; by mimicking the structural features of L-DOPA—the primary clinical treatment for Parkinson’s disease, which also utilizes LAT1—SK4 achieves superior brain delivery compared to traditional chelators. Experimental validation confirmed SK4’s role as a LAT1 substrate by showing that it strongly competes with phenylalanine for uptake and significantly promotes phenylalanine export in a trans-stimulation assay—the definitive proof of the transporter’s obligatory exchange mechanism [38,78,79]. The contrast between traditional iron sequestration and this advanced transport method is illustrated in Figure 6, which highlights how the SK4 molecule bypasses the BBB—a barrier that typically excludes large, hydrophilic agents like DFO—by utilizing the LAT1 transporter’s conformational exchange to enter brain tissue.

In in vitro experiments utilizing human dopaminergic neurons, SK4 demonstrated robust neuroprotective properties against diverse neurotoxic agents [48,78]. In the context of ferroptosis induction, SK4 effectively rescued neuronal loss and maintained neurite integrity in cells treated with the inducer erastin, showing efficacy comparable to DFP. This protection was further validated in three-dimensional neuronal organoids challenged with erastin. Furthermore, SK4 fully protected these human neurons against MPP⁺-induced mitochondrial toxicity and broader oxidative stress, confirming its role as a specialized iron chelator in neurodegenerative contexts. SK4 also provided protection against damage induced by externally added ferrous sulfate, reinforcing its high affinity and selectivity for iron [38].

Regarding its mechanism of action, SK4 displays a strong Fe³⁺ complex formation capacity that is superior to DFP at higher pH values, such as those characteristic of the mitochondrial matrix; this suggests enhanced chelation potency in critical subcellular compartments. Notably, SK4 showed no direct interaction with major reactive oxygen or nitrogen species, establishing that its neuroprotective activity is mediated predominantly through site-specific iron chelation rather than non-specific antioxidant scavenging [38].

Another endogenously identified chelator, the peptide thymosin β4, chelates both Fe²⁺ and Fe³⁺ ions across four distinct binding regions, thereby inhibiting erastin- and glutamate-induced ferroptosis. By restoring normal cellular morphology in macrophage cell lines and mitigating damage linked to iron accumulation, this peptide functions as a “ferroptosis switcher” that regulates the transition between cell survival and death [35,80].

Ferroptosis plays a critical role in both chronic neurodegenerative decline and acute tissue damage associated with I/R injury [36,67]. In acute hepatic I/R injury, which occurs during liver transplantation, iron accumulation is an independent risk factor for graft failure. This process involves programmed cell death and LPO, a cascade significantly attenuated by DFO pre-treatment. Furthermore, the specific ferroptosis inhibitor Fer-1, or the antioxidant α-tocopherol, effectively prevents hepatic damage and markers of ferroptotic signaling. Fer-1 also inhibits subsequent necroinflammation, suggesting that ferroptosis is an upstream trigger for the broader inflammatory response in hepatic I/R injury. This mechanism is further supported by the observation that dietary iron overload significantly exacerbates hepatic I/R injury and LPO, and this exacerbated damage remains sensitive to inhibition by Fer-1 [67,81].

In chronic CNS degeneration conditions such as MS, PD, and ALS, iron deposition in affected brain regions is a hallmark feature [70,71,82]. However, ferroptosis contributes to CNS pathology even in the absence of overt iron accumulation, often due to transient increases in bioactive iron coupled with reduced ferritin storage capacity—a phenomenon demonstrated in the cuprizone model of demyelination [36]. Regarding inhibition, the highly potent RTA Cu^II(atsm), currently in clinical trials for ALS and PD, directly blocks ferroptotic neuronal death and LPO in vitro with nanomolar efficacy comparable to Lip-1. This antiferroptotic activity is attributed to Cu^II(atsm) acting as a lipid RTA, independent of alterations to the oxidation state of intracellular iron. The analogous Ni^II(atsm) complex exhibits comparable potency, suggesting that efficacy relies primarily on the conjugated conformation of the ligand as stabilized by the metal ion; this enables the ligand to serve as an H-atom donor to quench lipid peroxyl radicals. This mechanism, combined with favorable oral bioavailability and brain penetrance, highlights a promising avenue for disease-modifying therapy in ferroptosis-related neurological disorders [30].

The metabolism of copper and iron ions is intrinsically linked, a phenomenon most clearly demonstrated by the unexpected induction of iron-dependent ferroptosis following copper chelation in neurodegenerative scenarios [83]. In the cuprizone mouse system, a widely used system to study demyelination relevant to MS, the copper chelator cuprizone triggers oligodendrocyte loss via ferroptosis. This toxicity arises because copper is an obligatory cofactor for multicopper ferroxidases, such as ceruloplasmin and hephaestin, which are required for efficient cellular iron efflux [36,84].

Chelation of copper disrupts this intricate system in oligodendrocytes, resulting in heightened intracellular iron load through multiple pathways [36,85]. Specifically, cuprizone reduces the functional activity of the oligodendrocyte-specific multicopper oxidase hephaestin, which impairs the oxidation of Fe²⁺ to Fe³⁺ required for export via ferroportin, thus inhibiting iron efflux. Simultaneously, copper chelation upregulates the transferrin receptor 1, increasing iron uptake. Critically, the process accelerates the expression of the ferritin cargo receptor, leading to ferritinophagy—the targeted autophagic degradation of the iron storage protein ferritin. This releases bioactive Fe²⁺ from storage into the LIP. The resulting surge of unbound Fe²⁺ generates massive ROS via the Fenton reaction, overwhelming the depleted antioxidant defenses (GSH and GPX4 are reduced), thereby driving lethal LPO and initiating ferroptosis [36,86].

Conversely, certain copper-containing molecules function actively as inhibitors of ferroptosis, particularly in neuronal protection, through a mechanism independent of iron chelation. The complex Cu^II(atsm) ameliorates neurodegeneration and delays disease progression in preclinical studies of ALS and PD, suggesting its mechanism involves blocking ferroptosis. Mechanistic investigation confirms that Cu^II(atsm) acts as a potent RTA, effectively blocking ferroptotic neuronal death and inhibiting LPO in vitro with nanomolar efficacy comparable to Lip-1 [30].

The specific antiferroptotic activity of Cu^II(atsm) and its analogous Ni^II(atsm) is derived from the coordinated ligand structure, rather than the metal ion itself promoting ROS scavenging [30,87]. The complex inhibits LPO without altering the oxidation state of iron species. The metal ion -Cu(II) or Ni(II)- facilitates the necessary double deprotonation of the ligand, forming a resonance-stabilized conjugated conformation where the NH-CH₃ functional groups act as H-atom donors to quench chain-carrying lipid peroxyl radicals. This structural requirement is critical: modifications that replace these essential NH-CH₃ groups markedly attenuate the complex’s ability to prevent ferroptosis. Conversely, simply increasing intracellular copper concentrations via ionic copper (CuSO₄) or non-protective copper ionophores fails to prevent ferroptosis. This demonstrates that the therapeutic mechanism is specific to the complex acting as an RTA and is not achieved merely by elevating cellular copper levels [30].

In oncology, the co-delivery of iron and copper ions has emerged as a superior strategy to synergistically induce cell death, overcoming the resistance posed by redundant survival pathways. This synergy is rooted in the mutually reinforcing disruption of cellular redox homeostasis and metal efflux mechanisms. Mechanistically, therapeutic effectors, often delivered via bimetallic nanoplatforms such as Fe-Cu MPNs or specialized hollow PB nanozymes, leverage the catalytic activity of both metals. The platforms release Fe²⁺ and Cu⁺ in the acidic, GSH-rich TME, facilitating Fenton or Fenton-like reactions that generate highly toxic hydroxyl radicals and ensuing LPO. Critically, this process simultaneously targets the central cellular defense system by rapidly depleting GSH, which serves both as a cofactor for GPX4 and a chelator for Cu⁺ [31,33,34,44,45,52].

Specific strategies refine this dual attack through integrated metabolic interference. First, dual GSH depletion and triple synergy is achieved with nanoplatforms like CuFeGA MPNs that exploit a novel dual GSH consumption approach: initial exposure to TME triggers the dissociation of the MPNs, releasing GA, Fe²⁺, and Cu⁺ for primary GSH consumption, followed by a second phase where the liberated GA further accelerates the depletion of remaining GSH. This profound redox collapse leads to the simultaneous activation of apoptosis (via amplified ROS), ferroptosis (via GPX4 inactivation), and cuproptosis (via Cu⁺ binding to lipoylated proteins such as DLAT) [52].

The convergence of ferroptosis and cuproptosis is fundamentally orchestrated through efflux disruption, a process wherein ferroptotic signaling pathways are exploited to cripple the cellular copper export machinery. Intense LPO and oxidative stress, driven by Fe/Cu-mediated Fenton reactions, inflict catastrophic mitochondrial damage that depletes intracellular ATP stores. Since the copper-transporting P-type ATPases (such as ATP7A) are strictly ATP-dependent, this metabolic crisis directly inhibits their expression and export capacity, leading to a toxic intracellular copper surge. This accumulation acts as a catalyst for cuproptosis by inducing the proteotoxic aggregation of lipoylated DLAT [33,34,44,60]. In CRC, the copper chelator Elesclomol exemplifies this synergy; it initiates ROS-driven ferroptosis while simultaneously promoting the ubiquitin-mediated degradation of ATP7A. This loss of ATP7A ensures sustained copper retention, which subsequently triggers the degradation of System xc− to further amplify ferroptotic cell death [60]. This mechanism is reinforced by FDX1 stabilization, where ferroptosis inducers inhibit the mitochondrial matrix proteases that typically regulate FDX1 turnover. By preventing the degradation of FDX1, these inducers stabilize the lipoylation machinery, effectively lowering the threshold for cuproptosis and ensuring a multi-pronged therapeutic attack on the cell [58].

Finally, gene editing for enhanced synergism is utilized to permanently bypass the limitations of transient metabolic inhibition. Advanced nanoplatforms now integrate CRISPR-Cas9 machinery to ensure sustained intracellular copper accumulation. For instance, RNP@Cu₂O@SPF nanocarriers deliver CRISPR-Cas9 RNPs specifically to suppress the expression of ATP7A. This genomic knockdown of the primary copper exporter maintains high levels of cytoplasmic Cu⁺, thereby boosting CDT and driving a lethal trifecta: accelerated ferroptosis (via GSH depletion and GPX4 deactivation), intensified cuproptosis (via DLAT aggregation), and sustained ROS production [46].