The role of ferroptosis in the pathogenesis and treatment of breast cancer

Abstract

Background

Breast cancer remains one of the most prevalent malignancies and a leading cause of cancer-related mortality among women worldwide. Despite significant advancements in therapeutic strategies, including surgery, radiotherapy, chemotherapy, and targeted therapy, challenges such as drug resistance, recurrence, and metastasis persist, underscoring the urgent need for novel treatment paradigms. Ferroptosis, a newly characterized form of regulated cell death driven by iron-dependent lipid peroxidation, has emerged as a critical player in tumor biology. Its distinct mechanistic features and regulatory networks offer promising avenues for overcoming therapy resistance and improving clinical outcomes in breast cancer.

Main body

Ferroptosis is orchestrated by a complex interplay of metabolic and signaling pathways, primarily involving lipid peroxidation of polyunsaturated fatty acids (PUFAs), iron accumulation, and dysfunction of antioxidant systems such as the System Xc⁻/glutathione (GSH)/glutathione peroxidase 4 (GPX4) axis, as well as non-canonical pathways including FSP1-CoQ₁₀ and DHODH-CoQH₂. These pathways are intricately regulated by transcription factors (e.g., p53, NRF2, ATF3), epigenetic modifiers, and non-coding RNAs, linking ferroptosis to key cellular processes such as energy metabolism, redox homeostasis, and immune modulation. In breast cancer, ferroptosis plays a dual role in tumor suppression and immune regulation. It influences cancer stem cell maintenance, epithelial-mesenchymal transition (EMT), and the tumor microenvironment (TME) by modulating immune cell functions, including CD8⁺ T cells, tumor-associated macrophages (TAMs), and myeloid-derived suppressor cells (MDSCs). Notably, ferroptosis induction has been shown to enhance the efficacy of conventional therapies (e.g., chemotherapy, radiotherapy, and immunotherapy) and reverse drug resistance in various breast cancer subtypes, particularly triple-negative breast cancer (TNBC). Emerging evidence highlights the therapeutic potential of small-molecule inducers, natural compounds, and nanomedicines that target key ferroptosis regulators such as GPX4, ACSL4, SLC7A11, FSP1, and DHODH. Moreover, ferroptosis-related gene signatures have been increasingly utilized to construct prognostic models and predict therapeutic responses in breast cancer patients.

Conclusion

Ferroptosis represents a pivotal mechanism in the pathogenesis and therapeutic response of breast cancer. Targeting ferroptosis pathways offers a promising strategy to enhance treatment sensitivity, overcome drug resistance, and improve patient prognosis. Future research should focus on elucidating the precise molecular mechanisms governing ferroptosis in distinct breast cancer subtypes, developing highly specific and safe ferroptosis-inducing agents, and optimizing combination regimens with existing immunotherapies and targeted therapies to facilitate clinical translation.

The concept of ferroptosis originated from the discovery by Dolma et al. [1] in 2003 that the compound erastin could induce cell death in tumor cells with RAS oncogene mutations. Yang et al. [2] ascertained in 2008 that the compound RSL3 exerted similar effects to erastin and that neither apoptosis-related nor necrosis-related inhibitors reversed the cell death caused by erastin; however, iron chelators and antioxidants inhibited this form of cell death. Therefore, in 2012, Dixon et al. [3] formally named the erastin-induced cell death mode with distinct morphologic, biochemical, and genetic characteristics as ferroptosis. The key products of ferroptosis are reactive oxygen species (ROS) and lipid peroxides, and it plays a significant role in the pathogenesis and treatment of various diseases, including cancer [4], ischemia-reperfusion injury [5], and neurodegenerative diseases [6]. Studies have confirmed that ferroptosis enhances the sensitivity of breast cancer to radiotherapy and chemotherapy, inhibits the growth of breast cancer tissues, and suppresses distant metastases and the recurrence of cancerous tissues. We expect that the induction of ferroptosis will develop into a potential treatment strategy for breast cancer [7].

This study reviews the literature from the past decade using databases such as Web of Science, PubMed, and Scopus, with ferroptosis, breast cancer, and tumors as keywords. It comprehensively analyzes the mechanism of ferroptosis and its role in the occurrence, development, and treatment of breast cancer, aiming to provide theoretical support for further improving breast cancer treatment strategies and the development of targeted drugs.

Characteristics and molecular mechanisms governing ferroptosis

Characteristics of ferroptosis

Ferroptosis is a complex biologic process (Fig. 1) that differs from currently known programmed cell death modes in terms of morphology, biochemistry, and genetics. The most prominent morphologic feature of ferroptosis is the alteration in mitochondrial ultrastructure that is manifested by significant mitochondrial shrinkage, increased membrane density, and a reduction or disappearance of mitochondrial cristae, all while the nucleus maintains its normal size with uncondensed chromatin. The biochemical characteristics during ferroptosis include markedly elevated intracellular iron and ROS levels, substantial depletion of glutathione (GSH), inactivation of glutathione peroxidase 4 (GPX4), and a diminished mitochondrial membrane potential [8]. Numerous genes are involved in ferroptosis, including driver genes such as GPX4, SLC7A11, ACSL1, and ACSL4, as well as suppressor genes exemplified by TFRC and GSS [9]. These genes play crucial roles in the regulation of ferroptosis and its related diseases.

Fig. 1.

Mechanism of ferroptosis

Mechanisms underlying ferroptosis

Ferroptosis, as a distinct form of cell death, is determined by the exquisite interplay between its execution system and defensive buffering mechanisms. In cancer, it primarily functions through tumor suppression and modulation of the tumor microenvironment (TME) while also offering novel strategies for cancer treatment [10]. The mechanisms involve iron accumulation, the Fenton reaction, and the synthesis and peroxidation of polyunsaturated fatty acid phospholipids (PUFA-PLs), whereas the primary defense mechanism comprises the System Xc-/GSH/GPX4 pathway [11–12]. In addition, two non-canonical antioxidant systems, the FSP1 CoQH2 system and the DHODH CoQH2 system, are also widely recognized [13].

Lipid peroxidation

As the principal component of cell membranes, excessive oxidation of lipids can alter the physical properties of cellular membranes; and this may lead to covalent modifications of proteins and nucleic acids. Lipid peroxides are divided into two major categories: lipid endoperoxides and lipid hydroperoxides, and both play important roles in many diseases such as inflammation, Alzheimer’s disease, and cancer [14]. The primary substrates of lipid peroxidation are PUFAs, which contain two or more double bonds in their carbon chains; examples are arachidonic acid (AA) and adrenic acid (AdA). Of these, PUFAs that contain bis-allylic groups are prone to peroxidation, and this process constitutes a crucial step in triggering ferroptosis [15–16]. Free PUFAs are conjugated with CoA by acyl-CoA synthetase long-chain family member 4 (ACSL4) to generate AA/AdA-CoA, which is then incorporated into phosphatidylethanolamine (PE) by lysophosphatidylcholine acyltransferase 3 (LPCAT3). Among various membrane phospholipids, PE-AA and PE-AdA are more prone to undergoing lipid peroxidation [17], and lipid peroxidation primarily occurs via enzymatic lipid peroxidation and non-enzymatic spontaneous-oxidation pathways. Lipoxygenases (LOXs) and cyclooxygenases (COXs) are acknowledged to participate in the enzymatic lipid peroxidation process. COXs principally act on free PUFAs, ultimately promoting the formation of prostaglandins [18].

Iron metabolism

LOXs are non-heme iron-containing dioxygenases that catalyze the generation of lipid hydroperoxides from free PUFAs [19].

During non-enzymatic lipid peroxidation, the hydrogen atoms on the bis-allylic positions of PUFAs are susceptible to reactions with free radicals (such as ROS) [20] due to the presence of unsaturated double bonds, thereby initiating the lipid peroxidation process. The lipid peroxides generated from the chain reaction between PUFAs and ROS further promote the chain until the free radicals are decomposed by antioxidants or form stable non-radical products—at which point the chain reaction terminates [18]. Under normal conditions, intracellular iron is in a dynamic equilibrium state, while excessive intracellular iron can induce ferroptosis. Investigators have ascertained that when cells absorb excessive Fe²⁺ from the external environment, the iron can combine with H₂O₂ to undergo the Fenton reaction, generating Fe³⁺ and a large amount of ROS—thereby promoting the formation of lipid peroxides from PUFAs. Iron-containing enzymes such as LOXs [21] are also able to catalyze free PUFAs to produce lipid hydroperoxides. In addition to the Fenton reaction, Fe²⁺ can react with lipid peroxides to form Fe³⁺, which can enter cells through the transferrin receptor (TFRC) and accumulate in endosomes. Within endosomes, the STEAP3 metalloreductase reduces Fe³⁺ to Fe²⁺, and Fe²⁺ is then released from endosomes into the labile iron pool in the cytoplasm via SLC11A2/DMT1 [22]. Excess iron is stored in ferritin or enters the bloodstream [23], leading to excessive absorption of Fe²⁺ and the triggering of ferroptosis in cells.

Antioxidant system metabolism

To counteract ferroptosis, cells possess an antioxidant system and its cofactors such as GPX4, ferroptosis inhibitor protein 1 (FSP1), tetrahydrobiopterin (BH4), and dihydroorotate dehydrogenase (DHODH). GPX4 is a selenoprotein that can reduce H₂O₂ in cell membranes using GSH as a cofactor [24]. Another antioxidant system is the glutamate-cystine antiporter system (System Xc−) that consists of the catalytic subunit solute carrier family 7 member 11 (SLC7A11) and SLC3A2. System Xc− mediates the exchange of intracellular glutamate for extracellular cystine and thereby regulates ferroptosis through GSH synthesis [25]. As a critical component of the cellular antioxidant system, GSH synthesis relies on cysteine, and cysteine is supplied by the System Xc− transporter or synthesized from methionine via the transsulfuration pathway [26–27]. The synthesized GSH ultimately protects cells from oxidative damage by reducing ROS and reactive nitrogen species. Glutamate-cysteine ligase activity and cysteine concentration can then regulate GSH synthesis and influence GPX4 activity [28–30]. GPX4 reduces toxic phospholipid hydroperoxides (PE-AA/AdA-OOH) into their corresponding non-toxic phospholipid alcohols (PL-OH), and GPX4 deficiency raises phospholipid hydroperoxides, thereby promoting lipoxygenase-mediated lipid peroxidation and ultimately leading to ferroptosis [23, 31]. In 2019, Doll et al. [32] discovered that the FSP1-CoQ pathway functions as an independent antioxidant system that cooperates with GPX4 and GSH to suppress phospholipid peroxidation and ferroptosis. Ubiquinone (CoQ10) [33] is a mobile lipophilic electron carrier belonging to endogenously synthesized lipid-soluble antioxidants, and it acts as a lipophilic radical-trapping agent in plasma membranes. FSP1, originally called apoptosis-inducing factor mitochondrial-related 2 (AIFM2), is a ferroptosis suppressor [33], and it is recruited to the plasma membrane and utilizes NAD(P)H to reduce ubiquinone (CoQ10) [34] into its radical-trapping antioxidant form, panthenol (CoQ10H2). This process subsequently diminishes phospholipid oxidation and directly inhibits lipid peroxidation [35]. The FSP1-CoQ pathway is regulated by BH4 and DHODH. Soula et al. [36] demonstrated that BH4 is a potent endogenous radical-trapping antioxidant that inhibits ferroptosis by promoting the formation of CoQ10 and blocking the peroxidation of specific lipids, a process independent of GPX4. DHODH, located in the mitochondria, can reduce CoQ10 to CoQ10H2, thereby suppressing ferroptosis [37–38].

Regulatory mechanisms underlying ferroptosis

Transcriptional regulation of ferroptosis

Ferroptosis is a relatively complex biologic process that is regulated by various genes and transcription factors. Dodson et al. [39] found that NRF2, a major antioxidant transcription factor, can inhibit ferroptosis by regulating SLC7A11 and GPX4; and it is also involved in modulating cellular GSH synthesis, iron metabolism, and intermediate metabolites. Wang et al. [40] showed that activating transcription factor 3 (ATF3) is a transcriptional repressor of SLC7A11, and other studies have revealed that the tumor suppressor gene p53 exhibits a dual or dichotomous regulatory effect on ferroptosis. p53 acts as a transcriptional repressor of SLC7A11 and can promote ferroptosis by inhibiting cysteine uptake [41], but it also enhances the activity of 15-LOX by upregulating the expression of spermidine/spermine N1-acetyltransferase 1 (SAT1) [25, 31]. As an iron-binding enzyme, 15-LOX oxidizes PUFAs and promotes lipid peroxidation [42]; but in contradistinction, p53 can inhibit ferroptosis by directly suppressing the activity of dipeptidyl peptidase 4 (DPP4) [25]. p53 also induces the expression of p21 through the p53/p21 transcriptional pathway to suppress ferroptosis, thereby protecting cancer cells from survival under cystine deprivation [43]. Sterol regulatory element-binding protein 1 (SREBP1) [44] is a central transcription factor that regulates lipid metabolism and inhibits ferroptosis by modulating stearoyl-CoA desaturase-1 to produce monounsaturated fatty acids (MUFAs). Investigators have also reported that under endoplasmic reticulum stress, activated transcription factors (ATFs) can transcriptionally activate ferroptosis-related genes [16], regulating the process of ferroptosis. In addition to being regulated by various genes, ferroptosis is also modulated by numerous non-coding RNAs. Yang et al. [45] found that circRNA FNDC3B inhibited ferroptosis in oral squamous cell carcinoma by regulating the miR-520d-5p/SLC7A11 axis; and Lu et al. [46] discovered that MiR-27a-3p regulated the ferroptotic process in non-small cell lung cancer by targeting SLC7A11. The regulation of ferroptosis is therefore certainly a complex systematic process.

Regulation of energy metabolism in ferroptosis

Recent studies have shown that cellular energy metabolism activities participate in the regulation of ferroptosis. Due to the rapid proliferation and enhanced metabolic rates of tumor cells, tumor energy metabolism has developed into a target for disrupting redox homeostasis and inducing ferroptosis [47]. Xie et al. [48] demonstrated that moderate temperatures (45 °C) significantly reduced the expression of antioxidants and triggered reprogramming of lipid metabolism in tumor cells loaded with iron oxide nanoparticles (Fe₃O₄ NPs). This disrupted the redox homeostasis in the tumors and induced lipid peroxidation, thereby sensitizing the tumor cells to ferroptosis and ultimately synergistically inducing ferroptosis. It is noteworthy to add that tumor cells can activate adaptive metabolic responses to suppress ferroptosis for self-protection, including the activation of glycolysis and the pentose phosphate pathway. AMPK serves as a pivotal hub for sensing and regulating balance in cellular energy metabolism. When intracellular energy metabolism is insufficient, the diminution in ATP content leads to an increased AMP/ATP ratio, ultimately activating AMPK [49]. Studies by Lee et al. [50–51] revealed that energy stress activated AMPK, which inhibited acetyl-CoA carboxylase (ACC) activity and reduced the synthesis of PUFAs, thereby ultimately suppressing ferroptosis. Song et al. [52] found that AMPK also mediated the phosphorylation of Beclin 1 (BECN1), thus promoting the formation of the BECN1-SLC7A11 complex so as to inhibit System Xc−, thereby promoting ferroptosis. Through siRNA screening, Song et al. [53] identified pyruvate dehydrogenase kinase 4 (PDK4) as the key gene mediating metabolic resistance to ferroptosis. They uncovered a block of pyruvate oxidation by PDK4 that restricted monosaccharides from entering the tricarboxylic acid cycle and fatty acid synthesis; and this reduced the production of PUFAs in a manner similar to that with AMPK activation, thus playing a regulatory role in ferroptosis.

A role for ferroptosis in tumors

Impact of ferroptosis on tumor initiation and progression

Recent studies have revealed that genes, proteins, and iron homeostasis involved in the ferroptotic process can influence tumorigenesis, progression, and metastasis. Compared to normal cancer cells, cancer stem cells (CSCs) are more susceptible to ferroptosis [54], and alterations in iron homeostasis in CSCs are typically characterized by elevated intracellular iron levels [55]. Iron can regulate the ferroptotic process and is significant in maintaining the stemness of CSCs [56]. Although CSCs are sensitive to ferroptosis, they can also suppress ferroptosis by increasing GSH levels [57]. Ferroportin (FPN) is the sole iron-exporter protein involved in regulating intracellular iron concentration [58], and FPN influences tumor progression by disrupting iron homeostasis. Studies have revealed that inhibiting FPN expression can induce cadmium-induced proliferation, the epithelial-mesenchymal transition (EMT), and migration of MDA-MB-231 cells [59]. Liu et al. [60] analyzed the relationship between 19 ferroptosis-related genes and migration-associated genes and demonstrated a positive correlation between ferroptosis and glioma cell migration. You et al. [61] uncovered samples with a high expression of ferroptosis-related genes in which multiple immune and stromal cells were recruited in the tumor microenvironment to promote tumor invasion and metastasis. Non-coding RNAs also regulate ferroptosis-related genes and thereby influence ferroptosis and tumor progression and metastasis. Xu et al. [62] found that circIL4R inhibited ferroptosis and promoted hepatocellular carcinoma tumorigenesis by regulating miR-541-3p/GPX4; and Zhang et al. [63] ascertained that the inhibition of miR-339 elevated the expression of the ferroptosis-related gene SLC7A11, suppressing ferroptosis and promoting lung adenocarcinoma metastasis. Since the EMT is involved in mediating treatment resistance in various tumors, it has been associated with tumor metastasis and ferroptosis. Mani et al. [64] found that inducing the EMT in human mammary epithelial cells (HMLEs) not only conferred a mesenchymal cell phenotype but also stemness. Therefore, tumor cells that acquired a mesenchymal cell state (e.g., CSCs) are now acknowledged to be associated with tumor metastasis and chemotherapeutic resistance [65–66]. Shi et al. [67] demonstrated that the EMT and the ferroptosis-related genes PCOLCE and HOXC11 were correlated with liver and lymphatic infiltration in colon adenocarcinoma patients; and other studies showed differential expression of EMT-related markers in GPX4-dependent cell lines [68]. Zinc-finger E-box-binding homeobox 1 (ZEB1) is a lipogenic factor that regulates lipid metabolism, bridging mesenchymal gene expression and vulnerability to lipid peroxidation; and Lee et al. [71] found that the expression of EMT markers was closely associated with susceptibility to ferroptosis. Drug-resistant cells in a highly mesenchymal state and exhibiting typical characteristics of mesenchymal-drug resistance depend upon GPX4 for survival [69] and are highly sensitive to ferroptosis induced by GPX4 inhibition [70].Ferroptosis plays a significant role in the progression of breast cancer, and inducing ferroptosis in tumor cells can effectively prevent their malignant progression in patients, thereby improving patients’ survival and prognosis.

Relationship between ferroptosis and tumor immunity

Ferroptosis is a double-edged sword with respect to regulating tumor immunity. It can influence the phenotype and function of immune cells, but immune cells can also regulate the ferroptotic process in tumor cells. As an illustration, IFN-γ secreted by activated CD8 + T cells can inhibit system Xc- and ultimately induce ferroptosis in tumor cells, thereby exerting an anti-tumor effect. Cells undergoing ferroptosis are also able to release specific signals such as arachidonic acid and damage-associated molecular pattern proteins (DAMPs) (including high mobility group box 1 [HMGB1]) that mediate anti-tumor immunity [71]. Conversely, ferroptosis can lead to a chronic inflammatory state that facilitates the survival or immune evasion of adjacent tumor cells. Tumor cells that experience ferroptosis and tumor-infiltrating immune cells also can generate immunosuppressive mediators such as prostaglandin E2 (PGE2) so as to inhibit anti-tumor immunity and thus ultimately promote tumor growth. This is exemplified by the increase in intracellular lipid peroxidation products to induce ferroptosis via the inhibition of GPX4 in tumor cells while also promoting PGE2-mediated tumor immune evasion [72]. Recent studies have additionally revealed that tumor cells that undergo ferroptosis mediate the formation of a pro-tumor immune microenvironment that contributes to tumorigenesis and progression [73]. A comprehensive analysis of multiple studies indicates that activating ferroptosis can inhibit the progression and distant metastasis of breast cancer, increase sensitivity to chemotherapy and radiotherapy, and ferroptosis may serve as a new therapeutic target for inhibiting the proliferation of breast cancer cells, demonstrating great potential in the clinical treatment of breast cancer.Developing effective drugs that induce ferroptosis in breast cancer cells may have a more significant effect on killing breast cancer cells, thereby inhibiting tumor growth, effectively reducing the incidence of invasion and metastasis, and significantly improving the therapeutic outcome of breast cancer.

Relationship between ferroptosis and immune cells

When the body confronts intracellular or extracellular stress stimuli, it activates ferroptosis as a defense mechanism [74], and tumor-infiltrating lymphocytes determine the immune activity against tumors and influence the efficacy of tumor immunotherapy [75]. Studies [76] have shown complex interactions between ferroptosis and immune cells such as macrophages and T cells within the tumor microenvironment. Tumor cells experiencing ferroptosis apparently remodel the tumor immune microenvironment by secreting cytokines and chemokines, thus regulating immune responses [77]. In contrast, immune cells also modulate ferroptosis in tumor cells during adaptation [78].

The immunostimulatory signals released by ferroptotic cells appear to serve as metaphorical “find me” and “eat me” signals that enhance the recognition and phagocytic capacity of macrophages [79–80]. For example, chemokine ligands (e.g., the chemokine C-C motif CCL) 2 or CCL7 can initiate macrophage recruitment and chemotaxis so as to amplify immune responses [81]. Oxidized phospholipids such as 1-palmitoyl-2-(5’-oxovaleroyl)-sn-glycero-3-phosphatidylethanolamine are recognized and bound by Toll-like receptor 2 on macrophages, and this action augments their phagocytic activity and facilitates the clearance of ferroptotic cells [82]. Tumor-associated macrophages (TAMs) are classified into two types: M1 and M2. The M1 type exhibits tumor-suppressive effects, while the M2 type promotes tumorigenesis, angiogenesis, and immune evasion [83]. M1 and M2 macrophages also show differential susceptibility to ferroptosis. M1 macrophages produce higher levels of inducible nitric oxide synthase (iNOS) and nitric oxide radicals (NO·) that can inhibit lipid peroxidation and thereby resist ferroptosis; while M2 macrophages lack iNOS and NO·, making them more sensitive to GPX4 inhibitor RSL3-induced ferroptosis [84].

The regulation of ferroptosis via the activity of CD8 + T cells in tumor infiltration and peripheral blood promotes dendritic cell maturation by mediating immunogenic cell death, and this enhances the infiltration and anti-tumor immune capacity of CD8 + T cells in the TME [80]. However, some studies [80] indicate that tumor-infiltrating CD8 + T cells are more sensitive to ferroptosis than tumor cells. As an example, CD36, a receptor responsible for fatty acid recognition and transport, mediates fatty acid uptake by tumor-infiltrating CD8 + T cells; and overexpression of CD36 induces lipid peroxidation and ferroptosis, leading to reduced generation of cytotoxic cytokines and impaired anti-tumor capability [85–86]. Conversely, CD8 + T cells can induce ferroptosis in tumor cells through multiple mechanisms, thereby exerting anti-tumor effects. Activated CD8 + T cells secrete interferon (IFN)-γ, which activates the JAK-STAT1 signaling pathway in tumor cells by binding to the interferon receptor (IFNR). This process, then, inhibits the expression of two subunits in the Xc-system, SLC3A2 and SLC7A11, reducing cystine uptake and GSH synthesis in tumor cells, thereby augmenting intracellular lipid peroxidation levels and weakening the tumor cell defense against ferroptosis. In contrast, this action stimulates the expression of lipid metabolism enzymes such as ACSL4 and LPCAT3 that enhance the production of lipid peroxides and induce ferroptosis in tumor cells [87–88].

Myeloid-derived suppressor cells (MDSCs) possess immunosuppressive functions, and they highly express ferroptosis-antagonizing substances such as N-acylsphingosine amidohydrolase 2 (ASAH2), prostaglandin E2 (PGE2), and the Xc-system so as to maintain iron homeostasis and cellular activation [89]; of these molecules, ASAH2 inhibits ferroptosis by reducing ROS generation. MDSCs selectively accumulate PGE2, thus decreasing lipid peroxide accumulation and enhancing resistance to ferroptosis [90]. MDSCs absorb large amounts of cystine via the Xc-system to enhance resistance to ferroptosis; but due to their lack of alanine-cysteine transporters, cysteine cannot be released into the microenvironment, and this leads to an insufficient energy supply for T cells and significantly impairs T cell activation, proliferation, and function [91]. Therefore, in tumors manifesting high MDSC infiltration, ferroptosis inducers that target the Xc-system are able to alleviate MDSC-mediated cysteine deprivation, promote T cell survival, and restore anti-tumor immune responses. Furthermore, polymorphonuclear myeloid-derived suppressor cells (PMN-MDSCs)—as major negative regulators of anti-tumor immunity—are highly susceptible to ferroptosis and undergo spontaneous ferroptosis in the TME. However, this process releases immunosuppressive molecules and limits T cell activity, thereby promoting tumor progression [92].

Additionally, regulatory T cells (Tregs) induce the high expression of GPX4 upon co-stimulation by the T cell receptor (TCR) and CD28 and regulate immune homeostasis and anti-tumor immunity. GPX4 gene deletion not only leads to excessive accumulation of lipid peroxides and ferroptosis in Treg cells but also promotes the production of IL-1β and accentuates the response of T helper cell 17 (Th17), boosting anti-tumor immune function [93–94].

Impact of ferroptosis on tumor immunotherapy

Targeting ferroptosis in combination with immunotherapy has achieved significant potential in the field of anti-tumor therapy. However, due to the varying sensitivities of immune cells to ferroptosis, the effects of targeting ferroptosis on tumor immunity tend to be associated with the distributional characteristics of immune cells in the TME. In “cold tumors” rich in immunosuppressive cells, ferroptosis can inhibit the function of cells such as MDSCs and Tregs, transforming the immunosuppressive microenvironment into an inflammatory environment that is enriched with anti-tumor immune cells that then counteracts the effects of immunotherapy. In contrast, the combination of targeting ferroptosis with immunotherapy enhances the efficacy of immune-checkpoint blockade therapy [88, 95, 96]. In disparate tumor types and contexts, ferroptosis-targeting therapy may exhibit the dichotomous effects of both inhibiting and promoting tumors. Therefore, improving the specificity of ferroptosis inducers, determining optimal dosages, and optimizing the sequence of combination immunotherapy are critical to intensify the efficacy of tumor treatment.

Correlation between ferroptosis and breast cancer

Onset and progression of ferroptosis in breast cancer

As a common downstream pathway of multiple gene-regulatory patterns, ferroptosis is closely associated with breast cancer progression. Chen et al. [97] found that transgelin (TAGLN1) interacted with SLC7A11, which promoted its ubiquitin-mediated proteasomal degradation and consequently induced tamoxifen resistance in breast cancer cells. The study by Lin et al. [98] showed that the upregulation of discoidin domain receptor tyrosine kinase 2 that is mediated by the EMT in recurrent breast tumors maintains the growth advantage of tumor cells while activating YAP/TAZ-mediated ferroptosis sensitivity; and this explains how recurrent tumor cells exhibit higher ferroptotic sensitivity. Additionally, in an analysis of the triple-negative breast cancer (TNBC) cell line BT549, the authors depicted acyl-CoA synthetase long-chain family member 1 as mediating the synthesis of α-eleostearic acid (aESA, a representative polyunsaturated acid) and thus inducing ferroptosis in BT549 cells. Since this type of ferroptosis could not be inhibited by GPX4 interference [99], the inhibition of aESA synthesis should provide a novel direction for the treatment of GPX4 inhibitor-resistant breast cancer.

Ferroptosis in breast cancer cells is also regulated by numerous non-coding RNAs. The circular RNA circGFRAl competitively binds to miR-228 and thereby modulates the expression of the target gene FSP1, mediating malignant tumor phenotypes [100]. The long non-coding RNA PGM5P3-AS1 stabilized the expression of the target gene microtubule-associated protein light chain C by interacting with the RNA-binding protein NOP58, promoted ferroptosis, and subsequently inhibited the malignant progression of TNBC [101]. Yadav et al. [102] demonstrated that SLC7A11, a downstream target of miR-5096, could be rescued to reduce miR-5096-mediated ferroptosis and its cancer-promoting effects. While numerous investigators have examined the association between non-coding RNAs and ferroptosis in breast cancer, current studies primarily focus on elucidating molecular relationships and investigating the potential of non-coding RNAs in predicting the presence of ferroptosis and tumor prognosis. We anticipate the synthesis of small-molecule compounds that target ferroptosis-related non-coding RNAs, and this may provide additional therapeutic approaches for breast cancer treatment.

The TME is a complex entity in which ferroptosis also plays a role. Xie et al. [103] initially uncovered the protective effect of adipocytes against ferroptosis in a co-culture system of adipocytes and breast cancer cells; and later studies revealed that oleic acid secreted by adipocytes inhibited ferroptosis in breast cancer cells in the presence of acyl-CoA synthetase long-chain family member 3. Liu et al. [104] found that breast cancer cells that were acutely exposed to high levels of 27-hydroxycholesterol exhibited lipid-metabolism disorders due to interference with sterol regulatory element-binding protein signaling, thereby inhibiting tumor cell growth. In contrast, breast cancer cells chronically exposed to high levels of 27-hydroxycholesterol demonstrated enhanced tumorigenic and metastatic capabilities. The underlying mechanism for these actions was attributed to the upregulation of GPX4 axis activity and a reduced dependence on the System Xc− antioxidant system in these cells, enabling them to adapt to the stress of abnormal lipid metabolism. This study also partially explained why obesity and high cholesterol serve as poor prognostic factors for tumors. Intriguingly, these researchers also ascertained that cellular interactions in the TME were associated with ferroptosis. TNBC cells produce interleukin-6, which activates the JAK2/STAT3 axis in tumor-associated macrophages and induces them to secrete TGF-β1. This, in turn, reactivates the TGF-β1 pathway in tumor cells and regulates the expression of hepatic leukemia factor (HLF), a novel oncoprotein. HLF transcriptionally activates γ-glutamyltransferase 1 to inhibit ferroptosis, thus promoting breast cancer growth and chemotherapeutic resistance [105]. The TME additionally exerts specific influences on tumor progression via the ferroptosis pathway.

Ferroptosis and prognostic prediction in breast cancer

Advances in bioinformatics have enabled researchers to identify ferroptosis-related genes from tumor databases and to construct prognostic-prediction models to improve a breast cancer-prognosis evaluation system. Wan et al. [106] screened 11 ferroptosis-related differentially expressed genes from the TCGA database and established a breast cancer prognostic prediction model, and multivariate COX regression analysis indicated that a high-risk score in this model was an independent risk factor for poor prognosis in breast cancer. Similar studies have also been conducted specifically for luminal-type breast cancer [107] on patients undergoing neoadjuvant therapy [108]. In another clinical study, Sha et al. [109] performed immunohistochemical testing on biopsy samples from breast cancer patients who received paclitaxel-cisplatin neoadjuvant chemotherapy to investigate the potential of the known ferroptosis-related genes ACSL4 and GPX4 as predictive markers for pathologically complete responses. These authors found that high ACSL4 expression, low GPX4 expression, and their combined status were independent prognostic factors for disease-free survival. There is also a close association between ferroptosis and breast cancer prognosis, with many differentially expressed genes identified as key players in the ferroptosis pathway that influence clinical outcomes. However, the functions of numerous genes remain unknown, and more in-depth molecular mechanistic studies could assist researchers in overcoming the limitations of bioinformatic prediction accuracy while identifying additional therapeutic targets for breast cancer treatment.

A role for ferroptosis in breast cancer therapy

Despite decades of research on breast cancer, its clinical treatment remains challenging. Ferroptosis, as a unique cell death mechanism, has garnered widespread attention in the field of oncology since its discovery, and studies have revealed that inducing ferroptosis inhibits breast cancer cells and enhances the efficacy of antitumor drugs and radiotherapy [110]. An increasing number of drugs that target the ferroptosis pathway have now been identified as promising therapeutic approaches for breast cancer.

Breast cancer therapy to target iron accumulation and metabolism

Intracellular free iron (Fe²⁺) catalyzes the generation of lipid peroxides through the Fenton reaction and serves as a key initiating factor in ferroptosis. Neratinib is a tyrosine kinase inhibitor and a commonly used targeting drug for HER2-positive breast cancer; it can increase TFR1 expression in cancer cells, induce iron accumulation and ferroptosis, and inhibit brain metastasis of tumor tissues in vivo [111]. Similar drugs include selinexor and lapatinib, which can increase TF content, promote intracellular iron accumulation, and induce ferroptosis in TNBC cells [112]. Liu et al. [113] demonstrated that transmembrane protein 189 (TMEM189) can be applied to inhibit autophagy in TNBC cells, reduce TFR1 expression and intracellular lipid ROS content, alleviate ferroptosis, and promote breast cancer growth in vivo—suggesting that TMEM189 inhibitors may be effective against TNBC. Shuganning injection is a patented drug in China that can selectively upregulate the expression of heme oxygenase 1 (HO-1) in TNBC cells, promote labile iron pool (LIP)iron accumulation and ferroptosis, and inhibit the growth of breast cancer tissues both in vitro and in vivo [114]. Artemisinin has been employed to increase intracellular Fe²⁺ levels and induce ferroptosis in TNBC cells by promoting ferritinophagy, enhancing the sensitivity of cancer tissues to the ferroptosis inducer RSL3, and suppressing breast cancer progression in vivo [115]. These drugs show promise as candidate treatments for TNBC. In recent years, nanoparticles that target breast cancer via the iron accumulation-ferroptosis mechanism have also been reported. Xu et al. [116] developed an Fe²⁺-centered nano metal-organic framework (MOF-Fe²⁺) that efficiently delivered Fe²⁺ to breast cancer cells, promoted the Fenton reaction and massive ROS generation, induced ferroptosis, and effectively inhibited breast tumor growth. Zhu et al. [117] constructed Fe³⁺-crosslinked nanoparticles loaded with trans-azobenzene-combrettastatin that specifically entered breast cancer cells, and upon infrared light irradiation, the loaded Fe³⁺ was converted to Fe²⁺, triggering the Fenton reaction and lipid peroxide accumulation to induce cancer cell ferroptosis. Application of these nanoparticles in mice resulted in significant shrinkage of breast tumors. Zhang et al. [118] designed a heparanase-driven cascade-releasing nanoparticle loaded with doxorubicin, ferrocene, and TGF-β receptor inhibitor SB431542, and after entering breast cancer cells, these nanoparticles elevated intracellular iron accumulation and ROS levels due to doxorubicin and ferrocene, activating ferroptosis and successfully inhibiting cancer tissue metastasis in mice.

Breast cancer therapy that targets the system Xc⁻/GSH/GPX4 axis

The System Xc⁻/GSH/GPX4 axis is the most important antioxidant defense mechanism in ferroptosis [119], and inhibiting its activity is an effective approach to suppressing breast cancer growth and treating breast cancer.

Investigators found that dihydroisotanshinone I, an active component of Salvia miltiorrhiza, promoted ferroptosis by inhibiting GPX4 expression in breast cancer cells, thereby suppressing tumor growth in mice without significant side effects [120]. The DMOCPTL derivative of the natural product parthenolide directly binds to the GPX4 protein, promoting GPX4 ubiquitination and inducing ferroptosis in breast cancer cells. In vivo, DMOCPTL effectively inhibited the growth of mouse mammary tumors and significantly prolonged the lifespan of mice [121]. Wen et al. [122] found that glycyrrhetinic acid reduced the activity of GSH and GPX4—exacerbating lipid peroxidation—and induced ferroptosis in breast cancer cells. Metformin was shown to upregulate miR-324-3p levels in TNBC cells and to target and inhibit GPX4 expression, promote ferroptosis, and significantly control tumor growth in vivo [123]. Yao et al. [124] reported that simvastatin (SIM) attenuated the activity of 3-hydroxy-3-methylglutaryl-coenzyme A reductase to inhibit the mevalonate pathway and GPX4 expression, thereby inducing ferroptosis in TNBC cells. These authors further loaded SIM onto zwitterionic polymer-coated magnetic nanoparticles (Fe3O4@PCBMA) and achieved significant anti-breast cancer effects in vivo. Currently approved by the U.S. Food and Drug Administration for clinical use, SIM may possess substantial clinically applicative potential in the treatment of breast cancer.

Li et al. [125] found that tumor-associated macrophages upregulated the expression of HLF in TNBC cells by secreting transforming growth factor-β1. HLF transcriptionally activates γ-glutamyl transpeptidase and catalyzes the cleavage of extracellular GSH, thereby increasing intracellular GSH levels in cancer cells. This process inhibits ferroptosis, enhances the proliferative and invasive capabilities of TNBC cells, and promotes cisplatin resistance in tumor tissues. Zou et al. [126] identified fibroblast growth factor receptor 4 (FGFR4) as a gene essential for acquired drug resistance in HER²⁺ breast cancer. Inhibition of FGFR4 in mice reduced GSH synthesis and Fe²⁺ efflux efficiency through the β-catenin/TCF4-SLC7A11/FPN1 axis, and this led to excessive ROS production, LIP iron accumulation, and ferroptosis—thereby enhancing the sensitivity of drug-resistant HER²⁺ breast cancer to chemotherapeutic agents. HLF and FGFR4 may then serve as targets for drug development in the prevention and treatment of breast cancer. A sonodynamic sensitizer containing a platinum(II)-indocyanine complex constitutes a novel breast cancer prevention and treatment compound that targets GSH and ferroptosis. This complex can reduce GSH levels in the TNBC cell line 4T1, promote ROS generation and ferroptosis, and enhance the sensitivity of cancer tissues to ultrasound radiation therapy [127]. Zhou et al. [128] developed a GSH-depleting dimer using cinnamaldehyde as material, and when combined with sorafenib, this dimer significantly enhanced ferroptosis in 4T1 cancer cells and successfully eradicated breast cancer in mice by promoting dendritic cell maturation and CD8 + T cell priming.

Actin-binding protein 1 directly binds to System Xc⁻, degrades System Xc⁻ through the ubiquitin-proteasome system, enhances the sensitivity of MCF7 cells to erastin, and inhibits breast cancer growth in vivo [129]. Another drug, sulfasalazine, promotes ferroptosis in breast cancer cells by specifically inhibiting the function of SLC3A1. Metformin also promotes ferroptosis in cells by inhibiting the UFMylation modification of SLC7A11 and downregulating SLC7A11 expression, with an enhancement of effects when used in combination with sulfasalazine [130]. Isoliquiritin reduces the expression of System Xc⁻ by inhibiting the NF-κB signaling pathway in MDA-MB-231 and MCF-7 cells, promotes ferroptosis, and alleviates the resistance of breast cancer tissues to doxorubicin [131]. Trastuzumab, in contrast, elevates the expression of the circular RNA BGN in the breast cancer cell lines BT474 and SKBR3, enhances the deubiquitination and expression of SLC7A11, inhibits ferroptosis, and induces drug resistance in cancer tissues; this effect was reversed by erastin [132].

ACSL4 and LPCAT3 are key enzymes in PUFA-PE synthesis [133–134], and the synthesis and peroxidation of PUFA-PLs in cell membranes are prerequisites and critical steps in the onset of ferroptosis. Compared with MUFAs, PUFAs contain oxidation-prone bis-allylic groups—particularly PUFA-PLs that contain phosphatidylethanolamine (PE) (PUFA-PE)—and are most susceptible to iron-catalyzed peroxidation. The accumulation of excessive lipid peroxides in cell membranes leads to membrane rupture and ferroptosis [135]. Sha et al. [136] collected biopsy specimens from breast cancer patients who underwent paclitaxel-cisplatin chemotherapy. Through log-rank tests and Cox proportional regression analysis, they found that both ACSL4 expression and ACSL4/GPX4 combination status served as independent predictors for an acquired pathological complete response. Moreover, ACSL4 expression revealed a positive correlation with patients’ overall survival rate. In the TNBC cell line MDA-MB-157, augmented expression of ACSL4 enhanced the sensitivity of cancer tissues to the ferroptosis inducer RSL3; while knockout of ACSL4 prevented RSL3-induced ferroptosis in cancer cells and inhibited tumor progression in vivo [32]. In contrast to ACSL4, MUFAs (such as octadecenoic acid) generated through ACSL3 or stearoyl-CoA desaturase 1 (SCD1)-mediated processes competitively inhibited PUFA-related ferroptosis by replacing phospholipids (PLs) in cell membranes to form MUFA-PLs. Studies have shown that inactivation of ACSL3 or SCD1 increased the susceptibility of breast cancer cells to ferroptosis [137–138]. Luis et al. [139] reported that the expression of SCD1 and fatty acid-binding protein 4 (FABP4) was significantly upregulated in human breast cancer specimens and that this was associated with poor prognosis in various types of breast cancers. Nuclear factor erythroid 2-related factor 2 (Nrf2) is a transcription factor that is crucial for oxidative stress response, and it can exert anti-inflammatory and anti-ferroptotic effects by inducing HO-1 expression and the suppression of ROS expression. Nrf2 has recently been shown to be important in the progression, treatment, and drug resistance of breast cancer. Jiang et al. [140] found that in breast cancer patients who received anti-PD-1/PD-L1 therapy, the expression of tyrosine-protein kinase receptor 3 (TYRO3) in tumor tissues was often positively correlated with poor prognosis. It is possible that anti-PD-1/PD-L1 induced the expression of TYRO3 in breast cancer tissues, which then further increased intracellular Nrf2 levels, reduced ROS generation, and remodeled a tumor-favorable microenvironment by inhibiting ferroptosis—thereby leading to resistance to anti-PD-1/PD-L1. Wu et al. [141] reported that overexpression of GSK-3β in TNBC cells inhibited Nrf2 expression, increased ROS and MDA levels, and enhanced erastin-triggered ferroptosis. In a breast cancer xenograft model, GSK-3β overexpression potentiated the inhibitory effect on tumor growth induced by erastin. The active compound ligustilide A extracted from Ligusticum chuanxiong disrupted mitochondrial structure and function in breast cancer cells by activating the Nrf2/HO-1 signaling pathway, thereby enhancing ROS-induced ferroptosis in TNBC cells, making it a potential lead compound in breast cancer treatment [142]. Ferroptosis suppressor protein 1 (FSP1) inhibits ferroptosis independently of GPX4, and as a flavoprotein, its encoding gene is considered to be a P53-responsive gene [143]. FSP1 functions as a glutathione-independent ferroptosis suppressor [32] and serves as a novel biomarker for anti-ferroptosis [144]. Silk fibroin nanoparticles that encapsulated rosuvastatin effectively inhibited the oxidoreductase activity of FSP1, slowing the malignant progression of TNBC [145].

Additionally, dihydroorotate dehydrogenase (DHODH) (located in the inner mitochondrial membrane) participates in pyrimidine synthesis and reduces CoQ to CoQH2 in the inner mitochondrial membrane. When DHODH activation promotes increased generation of CoQH2, it inhibits the lipid-peroxidation process in mitochondria, exerting an anti-ferroptotic effect. The DHODH inhibitor brequinar selectively suppressed the growth of GPX4-low tumors by inducing ferroptosis, while combination therapy with brequinar and sulfasalazine synergistically induced ferroptosis and inhibited the growth of GPX4-low tumors [146].

Therapy targeting other small molecules

Small molecule-induced ferroptosis inhibits tumor growth and enhances sensitivity to chemotherapeutic drugs. xCT, the functional subunit of system Xc, is responsible for the exchange of intracellular glutamate and extracellular Cys and is essential for the survival of TNBC cells. The transmembrane oncoprotein mucin 1-C-terminal subunit (MUC1-C) was aberrantly overexpressed in TNBC cells, and it interacted with xCT to maintain the redox balance of GSH. Hasegawa et al. [57] found that silencing MUC1-C expression in TNBC cells downregulated xCT expression and that this led to an imbalance in GSH levels and induced ROS-mediated cell death. In addition, the ferroptosis inhibitor ferrostatin-1 reversed the cell death generated by MUC1-C silencing. These authors also ascertained that TNBC cells with silenced MUC1-C expression were more sensitive to erastin-induced cell death when exposed to doxorubicin, fully demonstrating that MUC1-C exerted an anti-ferroptotic effect. We hypothesize that targeting the MUC1-C/xCT pathway might become a potential therapeutic approach for inducing cell death in TNBC.

Conclusions and future prospects

Breast cancer remains a leading cause of cancer-related mortality worldwide. Although significant progress has been made in breast cancer treatment over previous decades, the development of drug resistance and high recurrence rates necessitate the further exploration of therapeutic approaches. Growing evidence has in recent years revealed that ferroptosis induction successfully eliminates cancer cells that are resistant to other forms of cell death and enhances the sensitivity of breast cancer cells to antitumor therapies such as chemotherapy and radiotherapy. Most currently identified ferroptosis inducers remain at the preclinical research stage, but their efficacy, molecular targets, drug-resistance profiles, and potential adverse effects still require in-depth investigation. Furthermore, ferroptosis is an integral component of normal physiologic processes in the human body, and it is closely associated with numerous biologic processes such as iron metabolism, fatty acid metabolism, and glutathione regulation. Since excessive activation of ferroptosis may precipitate unpredictable damage to organs and systems, it is of critical importance to elucidate the mechanisms governing ferroptosis and to develop novel ferroptosis-based therapeutic approaches in the future.

Author contribution

Ming Zhang: Writing – original draft, Writing – review & editing. Qinyu Han: Conceptualization, Writing – original draft, Writing – review & editing. Xian Zhao: Writing – original draft, Writing – review & editing. Wenfeng Liu: Writing – original draft, Writing – review & editing. Min Lu: Writing – original draft, Writing – review & editing. Xiangqi Li: Conceptualization, Supervision, Writing – original draft, Writing – review & editing.

Funding

The present study was supported by the National Natural Science Foundation of China (grant no. 82274538);The Shandong Province Traditional Chinese Medicine Science and Technology Project, (Z20243705,MR20243701);Tai’an Science and Technology Innovation Development Project, (2021NS194);Beijing Weiai Public Welfare Foundation Jingyi Medical Research Phase II Research Project, (JvⅡ2025 − 01002 14028)༛.

Data availability

Data availability is not applicable to this article as no new data were created or analyzed in this study.

Declarations

Ethics and consent to participate

Not applicable.

Competing interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.