GPX4, a selenoprotein essential for cellular redox homeostasis, neutralizes PLOOHs on biological membranes by utilizing GSH as its obligate co-substrate (12). The cystine/glutamate transporter XC^-, a heterodimeric complex composed of Solute Carrier Family 7 Member 11 (SLC7A11) and Solute Carrier Family 3 Member 2 (SLC3A2), mediates cystine uptake in exchange for intracellular glutamate efflux (1, 13). Notably, SLC7A11 serves as the central regulator of ferroptosis by maintaining redox homeostasis through GSH synthesis (14).Multiple regulatory mechanisms govern the expression of transporter XC^-, encompassing targeted reduction of SLC7A11 levels, inhibition of SLC7A11 degradation and promotion of SLC7A11 expression, indicating that transporter XC^- can determine the susceptibility to ferroptosis (15, 16). Overall, both the biosynthesis/uptake of selenocysteine and the synthesis of GSH affect the homeostasis of GPX4, indicating that GPX4 plays a significant role in regulating ferroptosis (17, 18). Thus, the SLC7A11–GSH–GPX4 axis is believed to constitute the major cellular system defending against ferroptosis.

Paradoxically, upon GPX4 ablation, some cancer cell lineages remain resistant to ferroptosis revealing the existence of compensatory GPX4 independent defense mechanisms (19).

Emerging research has established the Ferroptosis inhibitor protein 1 (FSP1)- Ubiquinone (CoQ) axis as a parallel antioxidant system that functions as a compensatory mechanism specifically in GPX4-deficient cellular contexts (20). FSP1, originally characterized as apoptosis-inducing factor mitochondrial-associated protein 2 (AIFM2), has been redefined as a critical ferroptosis inhibitor through its N-terminal myristoylation-mediated membrane targeting. This membrane-localized oxidoreductase enzymatically reduces CoQ10, a mevalonate pathway-derived metabolity, to its reduced form ubiquinol. Apart from its well-known function in mitochondrial electron transport, it has been proposed that FSP1 exerts its potent anti-ferroptosis activity through generating the extra-mitochondrial CoQH2 pool as radical-trapping antioxidants (21, 22). The sources of the extra-mitochondrial CoQ harnessed by FSP1 for ferroptosis defense remain to be established.

Recent studies have positioned GTP cyclohydroxylase-1 (GCH1) as another critical regulator of ferroptosis (23, 24). Tetrahydrobiopterin (BH4), an essential redox cofactor, functions canonically in aromatic amino acid hydroxylation and nitric oxide synthase activity. Additionally, it serves as a critical mediator of ferroptosis resistance by catalyzing the rate-limiting step in the BH4 metabolic pathway (25). It was proposed that GCH1 confers ferroptosis resistance through the biosynthesis of BH4, which acts as a radical-trapping antioxidant, as well as through GCH1-mediated production of CoQH2 and Phospholipids (PLs) containing two Polyunsaturated Fatty Acid (PUFA) tails (23). The subcellular compartment wherein the GCH1–BH4 system operates needs to be investigated.

A recent study uncovered a mitochondria-localized antioxidant system mediated by Dihydroorotate Dehydrogenase (DHODH) capable of compensating for GPX4 deficiency by neutralizing lipid peroxidation within mitochondria (26). DHODH, a pyrimidine biosynthesis enzyme in the mitochondrial inner membrane, reduces CoQ to CoQH2. Therefore, DHODH functions as mitochondrial antioxidant system that protects against oxidative damage.

In addition, the crosstalk between ferroptosis and other signaling pathways has only been extensively studied in cancer. Key pathways such as PI3K-AKT-mTOR, LKB1-AMPK, E-cadherin-Hippo-YAP/TAZ, and VHL-HIF critically modulate ferroptosis in cancers via metabolic regulation and stress-response mechanisms (27).

In the future, integrating strategies to target ferroptosis defense pathways and enhance the efficacy of cancer immunotherapy will represent a promising therapeutic approach.

Ferroptosis of early tumor cells can promote the maturation and activation of DCs, enhance the antigen-presenting function of DCs, and stimulate effector T cells to exert anti-tumor effects (37). However, this beneficial effect appears to be context-dependent, as Wiernicki found that during the maturation of bone marrow-derived DCs (BMDCs), the expression of 12/15-LOX and the production of lipid peroxides increased, reversing cell maturations (38). This paradoxical finding suggests that ferroptosis may have dual roles in DC biology depending on cellular context and timing.

Indeed, ferroptosis can impair DCs antigen presentation through multiple mechanisms. Early lipid ROS accumulation downregulates CD86, CD40, and MHC II expression while reducing Interleukin-12(IL-12) and Interferon-γ(IFN-γ) secretion, impairing T cell activation (37). Beyond maturation inhibition, disrupted phosphatidylserine exposure and delayed calreticulin translocation (synchronized with membrane rupture) reduce phagocytic efficiency. The metabolic consequences are equally significant, with Oxidized Phospholipids (oxPL) uptake inducing lipid droplet accumulation while Acyl-CoA Synthetase Long-Chain Family Member 4 (ACSL4)-mediated membrane remodeling destabilizes immune synapses. These changes are compounded by transcriptional reprogramming, where coordinated NF-κB/STAT4/CCR7 downregulation and CCL3/4 upregulation, combined with ROS-induced mitochondrial/Endoplasmic Reticulum(ER) damage, collectively suppress antigen processing and MHC presentation (37, 39).

The progression of ferroptosis in DCs follows a distinct temporal pattern. Initially, lipid ROS accumulation impairs DC maturation and phagocytic capacity. As the process continues, transient calreticulin (CRT) exposure and ATP release occur during an intermediate phase, though immunogenicity remains limited. Ultimately, terminal membrane rupture releases DAMPs (High Mobility Group Box 1, HMGB1, Lactate Dehydrogenase, LDH) and cytokines (Tumor Necrosis Factor, TNF, IFN-β), while permanently impairing cross-presentation capability. This phased deterioration of DC function helps explain why the timing of ferroptosis induction is so critical for immune outcomes (37).

This timing dependence is clearly demonstrated by Efimova’s team, who showed that the GPX4 inhibitor RAS-Selective Lethal compound 3 (RSL3) stimulated ICD in tumor cells to activate DCs and induce anti-tumor immunity in an animal tumor model (40). Their work revealed that while early ferroptotic tumor cells (1 h post-RSL3) induced BMDC maturation, late ferroptotic cells (24 h post-RSL3) were simply phagocytosed without immunostimulatory effects. Importantly, the anti-tumor protection conferred by early ferroptotic cells depended on ATP-Purinergic Receptor P2X7 signaling, as blockade with oxidized-ATP abolished this effect, highlighting how DCs process and present tumor antigens via MHC complexes to activate T cells (41).

While DCs can enhance anti-tumor immunity through multiple mechanisms including NK cell activation, their function is particularly vulnerable in the tumor microenvironment. Tumor-infiltrating DCs, which tend to accumulate more lipids, show increased susceptibility to ferroptosis and consequent antigen presentation failure (42, 43). This vulnerability can be modulated, RSL3-induced DC dysfunction is reversible with Peroxisome Proliferator-Activated Receptor Gamma (PPARG) knockout, while Sestrin2 protects against Lipopolysaccharide (LPS)-induced ferroptosis (44). The accumulation of 4-Hydroxynonenal (4-HNE)-protein complexes in tumor-associated DCs further illustrates how oxidative stress can trigger DCs dysfunction through X-box Binding Protein 1 (XBP1) activation (45). Together, these findings paint a complex picture where ferroptosis-related molecules critically regulate DCs maturation and function, with important implications for both tumor immunology and therapeutic development.

NK cells, which are considered inherently immunized cells, are involved in the perforin/granzyme pathway, Factor Associated Suicide (Fas) and Factor Associated Suicide Ligand (FasL) interactions, TNF-α and TNFR-1 interactions, and antibody-dependent cytotoxicity (46). As they play an important role in anti-tumor immunity, their functional inhibition can promote tumor growth. It was found that the tumor-infiltrating NK cells contain higher levels of ferroptosis and lipid oxidation-related proteins, and the cell morphology was typical of ferroptosis (47). They have higher oxidative stress levels and weaker glucose metabolism, which eventually results in their dysfunction in the TME. Nuclear factor erythroid 2–related factor 2 (NRF2) helps NK cells regain anti-tumor activity in the TME (48). Therefore, ferroptosis of NK cells leads to insufficient anti-tumor immune function, which prevents the elimination and inhibition of tumor cells in a timely manner and helps tumor cells evade immune surveillance.

Neutrophils, originating from the bone marrow, are the first line of defense against microbial infection (49). In addition to other myeloid cells, neutrophils have been extensively investigated for their important role in cancer. Neutrophils have been shown to exert direct and indirect anti-tumor effects during the initiation of tumorigenesis and the early stages of tumor growth (50). Ly6G⁺ neutrophils inhibit B cell ferroptosis by secreting IL-6, which binds to the IL-6R on B cells and activates the downstream STAT3/SLC7A11 pathway. Molecules such as B-cell activating factor (BAFF) and A Proliferation-Inducing Ligand (APRIL) may also participate in the interaction between neutrophils and B cells, but IL-6 is the dominant signal. Treatment with anti-IL-6 antibodies significantly increases ferroptosis markers in B cells and reduces the GSH/Glutathione Disulfide (GSSG) ratio (51).

However, tumor-derived signals can alter bone marrow formation, leading to the expansion and pathological activation of neutrophils, called polymorphonuclear MDSCs (PMN-MDSCs) (52).

PMN-MDSCs play an immunosuppressive role by attenuating immune responses mediated by T cells, B cells, and NK cells. PMN-MDSCs employ three distinct but interconnected mechanisms to mediate immunosuppression. First, through metabolic regulation, their lipid peroxidation products (4-HNE and Malondialdehyde, MDA) directly activate arginase-1 (ARG1) and inducible nitric oxide synthase (iNOS), effectively suppressing T cell function (53). Second, by secreting inflammatory mediators, they upregulate Prostaglandin E2 (PGE2) biosynthesis genes, leading to enhanced PGE2 release that simultaneously inhibits T cell proliferation/function (54) and promotes the production of immunosuppressive cytokines IL-10 and transforming growth factor-β(TGF-β) (55). Finally, they exert direct cytotoxicity by impairing T cell antigen responsiveness through ROS generation and inducing Cytotoxic T cells (CTL) apoptosis via the Fas/FasL pathway (56).

Ferroptosis-related genes have been associated with genes found in PMN-MDSCs in various cancer types (54). A study analyzed liver metastases and adjacent normal tissues from a 63-year-old male Colorectal Cancer patient. Tissues were digested into single-cell suspensions, then processed by flow sorting and single-cell RNA sequencing, which revealed a significant increase in the death proportion of neutrophils. Additionally, pathways linked to ferroptosis, iron metabolism and glutathione metabolism were notably enriched in these granulocytes, providing the first evidence of immune cell ferroptosis in the TME (57). Previous studies suggested that N-Acylsphingosine Amidohydrolase 2 (ASAH2) is highly expressed in MDSC cells. Its inhibition enhances the stability of the p53 protein and upregulates Heme Oxygenase 1 (Hmox1), thereby inhibiting the production of lipid ROS and preventing the ferroptosis of MDSCs (58). In immunized mice, inhibition of ferroptosis through genetic and pharmacological means has been shown to counteract the immunosuppressive effects of PMN-MDSCs, inhibit tumor progression, and cooperate with immune checkpoint blockers (ICBs) to inhibit tumor growth (59).

Tumor-infiltrating PMN-MDSCs exhibit complex dual functions in anti-tumor immunity through ferroptosis-dependent mechanisms. These cells can promote tumor cell ferroptosis (particularly in glioblastoma), inducing tumor death and growth inhibition. Conversely, when PMN-MDSCs themselves undergo ferroptosis in the tumor microenvironment, they release lipid oxides via fatty acid transporter (FATP2)-mediated pathways, creating an immunosuppressive niche that paradoxically supports tumor progression. This immunosuppression involves the secretion of oxidized phospholipids and immunomodulatory factors that activate ARG1 and iNOS to suppress T cell proliferation (53). However, some studies have indicated that ferroptosis may suppress (rather than enhance) the immunosuppressive function of PMN-MDSCs (54). Notably, the net immunological impact appears context-dependent: while hepatocellular carcinoma models show that ferroptosis inhibition abolishes PMN-MDSC-mediated T cell suppression and synergizes with checkpoint inhibitors (60), non-small cell lung cancer studies demonstrate that ferroptosis inducers can simultaneously reduce MDSC accumulation and enhance T cell function (61). These divergent outcomes highlight tumor-type specific regulation of PMN-MDSC biology by ferroptosis, where the balance between direct tumoricidal effects and indirect immune modulation determines the ultimate therapeutic outcome.

A comprehensive elucidation of the mechanistic interplay between PMN-MDSCs and ferroptosis, particularly regarding their tumor-type-specific regulation of immune suppression versus activation, represents a crucial unmet need in the field.

Tumor-associated macrophages (TAMs) are the main immune cells in the TME, and a high degree of TAM infiltration often indicates a poor prognosis (62). Monocytes and mononuclear MDSCs (M-MDSCs) exhibit the same classical and pathologically activation patterns as the aforementioned neutrophils and PMN-MDSCs, respectively. They promote anti-tumor immunity by activating T cells and TAMs. Studies have shown that TAMs derived from M-MDSCs retain their immunosuppressive activity when compared with those derived from classical monocytes (63).M-MDSCs derived TAMs maintain immunosuppressive activity mainly by secreting various mediators, which promote angiogenesis and metastasis and facilitate tumor progression (64).

Treg cells are key inhibitory cells that maintain immune tolerance and escape of tumor cells. They are a subset of CD4⁺ T cells with immunosuppressive function and are composed of thymus-derived natural Treg cells and peripherally induced Treg cells. In the TME, Treg cells suppress the immune response and promote tumor immune escape by secreting cytokines such as IL-10 and TGF-β (85, 86). Treg cells deliver inhibitory signals through direct contact with antigen presenting cells or effector T cells via surface molecules (Cytotoxic T-Lymphocyte-Associated Protein 4, CTLA-4; PD-1). This contact-dependent suppression requires intercellular communication (e.g., cAMP transfer through gap junctions). During ferroptosis, Treg cells exhibit elevated mitochondrial superoxide (mitoSOX), disrupting OXPHOS and Fatty Acid Oxidation (FAO) - critical metabolic pathways that maintain Treg cells survival and suppressive function (35).Under the co-stimulation of the T-cell receptor/CD28, knockout of GPX4 in Treg cells increases the level of lipid oxidation and ferroptosis, resulting in the ferroptosis of Treg cells and suppression of their immunoregulatory function. Treg cells with GPX4 knockout can enhance TH17 cell-mediated inflammatory responses by secreting IL-1β. Furthermore, they can activate the function of DCs and CD8⁺ T cells, potentiating anti-tumor immune responses. Specific knockout of GPX4 in Treg cells has been shown to inhibit the growth of MC38 colon cancer and B16F10 melanoma xenografts in animal models (87).

Treg cells shape the immunosuppressive TME through multiple mechanisms, with their metabolic vulnerabilities (particularly ferroptosis sensitivity) offering a critical breakthrough for reversing tumor immune escape. Targeted modulation of Treg cell survival and function holds promise for reprogramming the TME from immunosuppressive to immunostimulatory states, thereby opening new avenues for cancer immunotherapy.

B cells produce and release antibodies against specific antigens, playing an important role in humoral immune responses (88). Upon activation, conventional B cells (usually called B2 cells) differentiate into plasma and memory B cells. Other B cell subtypes include B1 cells, marginal zone (MZ) B cells, follicular B cells, and regulatory B (Breg) cells. Follicular B cells are the largest group of B cells and are mainly involved in humoral immunity.

Different subtypes of B cells exhibit varying sensitivity to ferroptosis (89). A recent study showed that GPX4 is not required for the development and immune function of follicular B cells. However, it is required for both processes in B1 and MZ B cells because the loss of GPX4 expression in B1 and MZ B cells promotes lipid peroxidation and ferroptosis. Moreover, compared with follicular B cells, B1 and MZ B cells have higher expression of the fatty acid transporter CD36, which enhances their ability to internalize fatty acids.

Following CD36 binding to PUFAs, APT1-mediated depalmitoylation promotes the formation of a signaling complex between CD36 and spleen tyrosine kinase, triggering caveolae-mediated endocytosis. This process significantly increases intracellular PUFA accumulation, leading to a “lipid peroxidation storm” under GPX4-deficient conditions. While B1/MZ B cells can activate parallel antioxidant systems through exogenous CoQ10 supplementation or FSP1 overexpression, this pathway exhibits limited efficacy in follicular B cells (22). Concurrently, DAMPs such as HMGB1 released from ferroptotic B1/MZ B cells promote DC maturation via the TLR4/Myeloid differentiation primary response 88(MyD88) pathway while inducing IFN-γ secretion. IFN-γ inhibits GSH synthesis by downregulating SLC7A11, establishing a pro-ferroptotic positive feedback loop. Nuclear Receptor Coactivator 4(NCOA4)-mediated ferritinophagy increases free iron levels, which not only enhances Fenton reactions but also upregulates Transferrin Receptor 1(TfR1) expression through iron-responsive element (IRE) activation, further exacerbating iron overload (90). Follicular B cells maintain high IL-10 expression, which preserves reduced glutathione pools through STAT3 signaling while suppressing NADPH Oxidase 2(NOX2) activity, creating a dual antioxidant defense system (91). As an immunosuppressive cytokine, IL-10 inhibits the activity of T cells and NK cells to modulate immune responses and maintain immune homeostasis. Future studies should investigate combined CD36 inhibition and PD-L1 targeting strategies to protect B1 and MZ B cells from ferroptosis.

Altogether, ferroptosis is involved in the survival and potential anti-cancer effects of B cells. However, the specific underlying mechanisms warrant further investigation.

Iron-based nanomaterials account for a large proportion of nanoscale ferroptosis inducers, as iron itself is the key component of ROS produced by Fenton reaction and the process of ferroptosis depends on iron.

Iron oxide nanoparticles (IONPs) are key iron-based nanomaterials capable of inducing tumor ferroptosis (130). Shen’s team fabricated FeGd-HN@Pt@LF/RGD2 nanoparticles that crossed the blood-brain barrier via lactoferrin receptor-mediated transport and entered cancer cells through integrin endocytosis (118). These nanoparticles released Fe²⁺/Fe³⁺ for direct Fenton reactions and cisplatin-derived H₂O₂ for enhanced ROS generation, while enabling MRI-guided treatment monitoring. Wang’s team created Mn3[Co(CN)6]2@MIL-100(Fe) to co-deliver artesunate and Fe³⁺, where Fe²⁺ from Fenton reactions triggered ferroptosis via ROS accumulation (119). Yang’s team constructed an acid-sensitive nano-diagnostic agent (named FePt@MnO@DSPE-PEG5000-FA, [FMDF NPs]) to monitor the response of tumor cells to ferroptosis and chemotherapy via MRI (120). FA receptor-targeted nanocomposites enabled tumor-specific Fe²⁺ delivery, triggering Fenton-driven ROS generation from H₂O₂ to induce ferroptosis, while Mn²⁺ enhanced MRI contrast for real-time tumor localization. Sun’s team synthesized bcc-USINPs via pyrolysis to enhance Fenton reactions and intracellular Fe²⁺ cycling for ferroptosis induction (123). SFT nanoparticles were created by coating SRF with Fe³⁺/TA complexes, enabling tumor-selective ferroptosis (125). These nanoparticles selectively caused tumor cells ferroptosis and had minimal toxic effects on normal cells. Ascorbate combined with Fe³⁺/RSL3-loaded CaP nanocarriers synergistically increased tumor-specific H₂O₂ and GPX4 inhibition for ferroptosis (131). FA-targeted exosomes (erastin@FA-exo) improved erastin delivery to TNBC cells, depleting glutathione and elevating ROS to promote ferroptosis while reducing systemic toxicity (127).

While iron-free nanomaterials show biomedical potential, their application in ferroptosis-targeted cancer therapy remains limited due to iron’s central role in this process.

Kim et al. engineered sub-10 nm peptide/PEG-modified SiO₂ nanoparticles that triggered ferroptosis in nutrient-deprived cancer cells and murine tumors, validating their therapeutic efficacy (126). Ou’s LDL-DHA nanoparticles selectively induced hepatoma cell death and suppressed liver tumors via iron-dependent lipid peroxidation, GSH depletion, and GPX4 inactivation in cellular/animal models (121). Leveraging Mn-O bonds’ redox sensitivity to GSH depletion (consuming 2 GSH per bond) (132), Tang’s MMSNs depleted intracellular GSH to drive hepatocellular carcinoma ferroptosis (122).

Our team has advanced tumor ferroptosis-regulation nanomaterials, mirroring current research trends. We pioneered lactose-modified TCLM nanomicelles co-delivering Triapine/Ce6 as the first nano-DDS for Triapine-based therapy (128). Additionally, we engineered liver-targeting RF@LA-Fe-MOF nanoparticles integrating RSL3 and iFSP1 for precision ferroptosis modulation (129). Our team’s nanomaterials significantly reduce off-target toxicity through precise drug delivery. Compared to non-targeted nanomaterials, we’re the first to systematically achieve synergistic ferroptosis induction and immune microenvironment remodeling. Our advantages include: asialoglycoprotein receptor (ASGPR)-mediated efficient hepatic uptake, pH-responsive drug release for enhanced tumor accumulation, dual-target inhibition (GPX4 and FSP1) to overcome single-pathway resistance, and synergistic chemo-photodynamic therapy with Triapine and Ce6. While current ferroptosis-inducing nanomaterials show preclinical promise in animal models, their clinical translation requires rigorous validation to bridge the experimental-therapeutic gap.

We summarized common design principles emerging from research. In the field of targeted delivery, ligands such as lactobionic acid, folic acid, and apolipoproteins or targeting antibodies (e.g., PD-L1) have been utilized, thereby enhancing antitumor efficacy, improving tumor accumulation, and reducing off-target toxicity. Regarding stimuli-responsive strategies, leveraging TME features such as low pH, high GSH, and high ROS, Wang’s team constructed a dual tumor-feature (ATP and acidity) unlocked nanoplatform to amplify ferroptotic damage for efficient ferroptosis-based therapy (133). Zhang’s group reported a dual GSH/GPX4 depletion strategy using GSH-responsive polydopamine-based hybrid nanoparticles (CACuPDA) to induce tumor ferroptosis (134). Additionally, studies have identified the immune-enhancing properties of modulating TME ROS levels, guiding the selection of nanocarrier materials for nanodrug construction (135). For Fenton catalysis enhancement, iron-based nanoparticles (118)or manganese-based materials (e.g., MnO₂) have been integrated to promote •OH generation (120, 122). In terms of GPX4 inhibition, GPX4 inhibitors (e.g., RSL3, ML162) have been delivered (127, 129), or SLC7A11 has been modulated to promote tumor cell ferroptosis (125). For combination therapies, photothermal/photodynamic therapies (e.g., Ce6-loaded systems) (128)or chemotherapeutic drugs (e.g., cisplatin) have been combined for synergistic antitumor effects (136).

However, clinical translation faces several challenges: difficulties in large-scale production of complex nanostructures requiring precise control of layered compositions (118), systemic oxidative damage (e.g., hepatotoxicity) caused by free iron ions (137), long-term retention issues of certain metal nanoparticles (138), potential complement system activation or inflammatory responses triggered by nanoparticles (139) and limited delivery efficiency due to tumor stromal barriers and immunosuppressive TME (140). To address these issues, synthesis processes can be simplified by using liposomes or polymeric micelles (e.g., PLGA) instead of complex metal nanoparticles to reduce costs, organ targeting can be optimized to mitigate side effects from specific accumulation, biodegradable materials can be employed, surface modifications of nanomaterials can minimize antibody recognition, and co-delivery of hyaluronidase or collagenase can enhance penetration depth combined with PD-1 inhibitors to reverse immunosuppression.