Degradation and synthesis are tightly regulated in eukaryotic cells due to the continual turnover of substances. There are two main degradation systems in mammalian cells, lysosome (also called autophagy) and the proteasome (55). Autophagy is further divided into three categories, namely macroautophagy, microautophagy and chaperone-mediated autophagy. Since macroautophagy is the most prevalent kind of autophagy, it has been the subject of the most research. Studies have revealed that the regulation of ferroptosis involves autophagy in a complicated way. On the one hand, autophagy can protect cells from ferroptosis by eliminating damaged cellular components and decreasing iron content in cells (56). Additionally, excessive autophagy can promote ferroptosis (57, 58). Here, we introduce the relevant autophagy regulatory molecules and their function in ferroptosis.

Our understanding of the process and function of autophagy has considerably improved as a result of the discovery of ATGs ( 59). So far, more than 40 kinds of ATGs have been found in yeast cells. ATGs participate in multiple autophagy-activating stages, including initiation, nucleation, elongation, maturation, and fusion (60). Numerous investigations have discovered that autophagy is crucial to ferroptosis (61). In 2016, Daolin Tang et al. (62) found that knockout of ATG5 or ATG7 could inhibit erastin-induced ferroptosis, and further studies demonstrated that activation of the autophagy pathway promoted ferroptosis by degrading ferritin. Artesunate can induce ferroptosis in activated hepatic stellate cells, and up-regulation of ATG3, ATG5, ATG6/beclin1, ATG12 was observed (63). By triggering ferroptosis in clear cell ovarian cancer tissues, superparamagnetic iron oxide nanoparticles (SPIONs) suppress the activity of human ovarian cancer stem cells. Mechanism studies have found that ferroptosis is activated by reducing the autophagy activity of ovarian cancer stem cells. PCR analysis showed that SPIONs treated human ovarian cancer stem cells autophagy-related factors (ATG3, ATG5, MAP1ALC3a, MAP1ALC3b, and MAP1ALC3c) expression decreased (64). Unfortunately, the authors did not further explore the mechanism by which SPIONs promote ferroptosis, and whether they interact directly with ATG3 or ATG5. The above findings suggest that ferroptosis is the result of the joint action of multiple regulatory factors, rather than being regulated by a single factor.

NCOA4 is a protein that plays significant roles in cellular processes related to iron homeostasis and autophagy. Alec C Kimmelman et al. (65) discovered that NCOA4 was substantially enriched in autophagosomes using quantitative proteomics in 2014. Further research found that NCOA4 is essential for the transfer of ferritin to lysosomes, and cells missing NCOA4 are incapable of degrading ferritin. Thus identifying NCOA4 is a selective cargo receptor for ferritinophagy, which is vital for iron homeostasis (65, 66). Murphy et al. demonstrated that the interaction between NCOA4 and ferritin was exclusive to ferritin heavy chain (FTH1) specifically (66). By disrupting the NCOA4-FTH1 protein-protein interaction, it does reduce the amount of iron available to organisms in the cell, thus inhibiting ferroptosis (67). Blocking intestinal NCOA4 protects against iron overloading in a mouse model of hemochromatosis. And NCOA4-mediated intestinal ferritin phagosomes are regulated by HIF2α ( 68). Because NCOA4 plays a crucial part in ferroptosis, treating illnesses by targeting NCOA4 has become an area of intense research (69, 70).

IRPs regulate iron metabolism at the post-transcriptional level by binding to iron response elements (IREs) of target transcripts, such as TFR1and ferritin H and L subunits (71). Back in the 1990s, researchers discovered that IRPs regulate the amount of iron in cells (72). Initially IRP1 can increase the expression of TFR1and increase cells’ ability to absorb iron (73). Additionally, Galy et al. (74) used Cre/Lox technology to simultaneously ablate IRP1 and IRP2 in a tissue-specific manner, and found that IRP deficiency significantly reduced DMT1 mRNA expression. IRPs can also regulate ferritin expression. Under iron-deficient conditions, the expression of IRPs is increased and the translation of ferritin mRNA is inhibited; while in iron-rich cells, the binding of IRPs to the IRE of ferritin is reduced (75). Due to its important function in cellular iron homeostasis, its relationship with ferroptosis has attracted much attention in recent years. α-Enolase 1 (ENO1) is an essential glycolytic enzyme. Zhang et al. (76) discovered that ENO1 inhibits mitochondrial ferroptosis by inhibiting IRP1, and demonstrated through in vitro and in vivo experiments and clinical sample analysis that IRP1 exerts an anti-tumor effect in liver cancer cells by inducing ferroptosis. miRNAs are an essential post-transcriptional regulator involved in numerous physiological and pathological processes. By inhibiting IRP2 expression, MiR-19a inhibits ferroptosis in colorectal cancer cells, thereby promoting the progression of colorectal cancer (77). Studies have shown that elevated iron content in the liver is one of the main causes of liver steatosis. It was found that the levels of IRP2 mRNA and protein were increased in steatosis liver. Further research has found that mir-29a-3p can reduce the expression of IRP2, thereby lowering Fe²⁺ levels, thus inhibiting ferroptosis and improving cell damage, according to additional research (78). These studies indicate that modulating ferroptosis at the post-transcriptional level by regulating IRPs is conducive to the treatment of diseases.

HSPs are a class of important molecular chaperone proteins, including HSP110 (HSPH), HSP90 (HSPC), HSP70 (HSPA), HSP60(HSPD/E), HSP40 (DNAJ), and small heat shock proteins (HSPB), which are involved in a variety of physiological and pathological processes (79, 80).

HSP27, a key component of HSPB, protects cells from oxidative stress by inhibiting TFR1-mediated iron uptake and decreasing intracellular active iron (81). After ferroptosis was discovered, researchers quickly focused on the function of HSP27 in ferroptosis due to its critical role in controlling oxidative stress. Inhibiting HSP27 expression in vitro and in vivo can increase the anticancer activity of erastin mediated ferroptosis (82). Dihydroartemisinin (DHA) has cytotoxicity to various malignant tumors, but DHA attenuates ferroptosis in glioma cells through the PERK/ATF4/HSPA5 pathway (83). In pancreatic cancer, HSPA5 negatively regulated ferroptosis in human pancreatic ductal adenocarcinoma cells. In mechanism, HSPA5 reduces GPX4 protein degradation and subsequent lipid peroxidation, thus limiting the anticancer activity of gemcitabine (84). In addition, Zhou et al. (85) demonstrated that overexpression of DNAJB6 in esophageal cancer can promote the degradation of GSH, downregulate GPX4, enhance lipid peroxidation, and promote ferroptosis. Additionally, researchers have discovered that HSP90 and HSPA8 can promote GPX4 degradation via autophagy, thus promoting ferroptosis (86, 87). This indicates that the HSP family regulates ferroptosis through multiple pathways. More avenues may be discovered in the future.

The activation of heat shock factor 1 (HSF1) is triggered when cells are driven by external causes such as nutritional shortage, hypoxia, oxidative stress, and other similar conditions (88). Upon activation, HSF1 will translocate to the nucleus, thereby facilitating the transcriptional upregulation of HSPs (89). Since HSPs are directly regulated by HSF1, HSF1 plays a regulatory role in ferroptosis by regulating HSPs (90). Sun et al. (82) were the first to describe the regulatory role of the HSF1-HSPs signaling axis in ferroptosis in 2015. The researchers discovered that the suppression of the HSF1-HSPB1 pathway resulted in an augmentation of erastin-induced ferroptosis (82). A recent study discovered that HSF1 enhances prostate cancer cell resistance to ferroptosis by modulating HSPE1, and that HSF1 knockdown can promote prostate cancer cell sensitivity to RSL3 therapy (91). Furthermore, inhibiting HSF1 specifically can reverse the ferroptosis resistance generated by GPX4 suppression and greatly improve the in vitro sensitivity of resistant cancer cells and tumors to ferroptosis (92). Thus, it may be concluded that HSF1 is a promising target for ferroptosis.

Current researches have only revealed the function of some HSPs in iron metabolism and ferroptosis, and further researches on the effects of other HSPs are required in the future.

The PCBPs family includes five protein members, but current research mainly focuses on PCBP1 and PCBP2. As cytoplasmic iron chaperone protein, PCBP1 and PCBP2 bind to ferritin in the body, promoting iron loading into ferritin, thereby increasing the amount of iron loaded into ferritin (29, 93). The study discovered that mice lacking PCBP1 in hepatocytes exhibited defects in hepatic iron homeostasis, and ferroptosis occurred even in the absence of iron overload (94). In addition, the latest research found that PCBP1 can also inhibit the activation of ferritin autophagy by binding to BECN1 mRNA and inhibit the PUFAs peroxidation by restraining the expression of ALOX15 mRNA (95). As an RNA-binding protein, PCBP2 is able to bind and stabilize the expression of SLC7A11 mRNA, inhibiting malignancy ferroptosis and promoting tumor progression (96). In the future, enhancing the expression of PCBP1 and PCBP2 in malignant diseases may become a novel strategy for treating cancers.

Hepcidin is an iron-regulating hormone secreted by the liver. FPN, which is the only known cellular iron exporter, is found in duodenal epithelial cells, macrophages, and liver cells and can transport intracellular iron into plasma. The discovery of the hepcidin-FPN axis is a significant development in the field of systemic iron homeostasis. Hepcidin regulates FPN expression in two ways: inducing ubiquitination and endocytosis of FPN (97) and blocking FPN from opening the central cavity (98). A recent study revealed that hepcidin binding to FPN is coupled to iron binding, and the affinity of hepcidin increases 80 times in the presence of iron (99). Binding of hepcidin to FPN restricts iron export even if the transporter is in an outwardly open state (99). Subsequently, people began to pay attention to the role of hepcidin in diseases. It has been discovered that cigarette tar can accelerate the progression of atherosclerosis (AS) by inducing macrophage ferroptosis. Further research has confirmed that tar can upregulate the expression of macrophage hepcidin in AS plaques and downregulate the expression of FPN and SLC7A11. And this change can be reversed by ferroptosis inhibitors Fer-1 and DFO (100). Chlorogenic acid (CGA) is an intestinal protective agent. Studies have found that CGA reduces hepcidin production and increases the expression of FPN in the duodenum by inhibiting the liver IL-6/JAK2/STAT3 pathway, thereby restoring iron homeostasis and inhibiting ferroptosis (101). Current research on hepcidin and ferroptosis focuses primarily on benign diseases; in the future, it will be necessary to strengthen hepcidin research in malignant diseases.

NRF2 is a transcription factor that is crucial for cellular defense against oxidative stress and iron homeostasis. NRF2 regulates iron metabolism primarily via three pathways: Inhibiting the release of free iron from ferritin (102) and the expression of hepcidin (103); Promoting the expression of iron-related enzymes such as heme oxygenase-1 (HO-1) (104); Downregulating the expression of DMT1 to reduce iron uptake (105). Because it plays an important regulatory role in iron metabolism, NRF2 can also regulate ferroptosis. The expression of NRF2 is regulated by the p62-Keap1-NRF2 pathway. In 2016, Sun et al. (106) confirmed that activating the p62-Keap1-NRF2 pathway can inhibit ferroptosis in liver cancer cells. P62 is an autophagic protein, also known as SQSTM1 protein. The latest study found that autophagy inhibition can protect HepG2 cells from alcohol induced ferroptosis by activating the p62-Keap1-Nrf2 pathway (107). Theoretically, because NRF2 plays multiple functions in iron metabolism, it can theoretically regulate ferroptosis via various mechanisms. Finally, we summarize the mechanisms by which different genes modulate iron metabolism and their influence on ferroptosis ( Table 1 ).

LOXs are widely distributed in eukaryotes and prokaryotes, and it has received a lot of attention in eukaryotes. LOXs are enzymes that non-heme iron (or in some cases manganese) dependent, which can trigger the peroxidation of PUFAs to fatty acid hydroperoxides (108). Although most mammalian LOXs catalyze arachidonic acid and linoleic acid, some can also convert α-linolenic acid, eicosapentaenoic acid, and docosahexaenoic acid. There are six functional LOX genes in the human genome, designated LOX5, LOX12, LOX12B, LOX15, LOX15B and LOXE3. Multiple subtypes and subunits comprise LOXs, which are generalised lipoxygenases. Current research demonstrates that ALOXs is crucial for regulating ferroptosis. Microsomal glutathione S-transferase 1 (MGST1) is a membrane-bound transferase that not only inhibits apoptosis (109), but further studies have found that MGST1 reduces lipid peroxidation by combining with ALOX5, thereby inhibiting ferroptosis (110). ALOX15 can catalyze arachidonic acid to generate 15-Hydroperoxyeicosatetraenoic acid (15-HpETE), and 15-HpETE can promote the triggering of cardiomyocyte ferroptosis (111). In addition, the researchers discovered that the downregulation of ALOX15 expression in gastric cancer resulted in a decrease in ROS production, which ultimately led to a significant inhibition of ferroptosis, fostering tumor growth, and decreasing sensitivity to cisplatin and paclitaxel (112). In summary, ALOXs can play a significant role in the occurrence and regulation of ferroptosis by promoting the generation of phospholipid peroxidation products, boosting the production of ROS, and partaking in lipid peroxidation. Furthermore, ALOXs system-mediated ferroptosis is also regulated by P53 (113, 114).

ACSL can catalyze the combination of long-chain fatty acids and coenzyme A (CoA) to form long-chain acyl-CoA (acyl-CoA). Acyl-CoA participates in fatty acid metabolism, membrane modification, and numerous other physiological processes. There are five members of the animal ACSL family: ACSL1, ACSL3, ACSL4, ACSL5, and ACSL6. According to the current research, ACSL3 and ACSL4 are capable of regulating ferroptosis (115). Oleic acid protects melanoma cells from ferroptosis in an ACSL3-dependent manner, thereby facilitating melanoma metastasis (116). Similarly, in triple-negative breast cancer cells, the secretion of oleic acid from adipocytes increased in the presence of ACSL3, which can inhibit lipid peroxidation and ferroptosis in breast cancer cells (117). Furthermore, in a mouse model of myocardial infarction, the release of miR-223-3p, a platelet-enriched miRNA, was increased. Whereas miR-223-3p leads to decreased secretion of stearic acid-phosphatidylcholine in cardiomyocytes by targeting ACSL3, and stearic acid-phosphatidylcholine can protect cardiomyocytes from ferroptosis (118). Consequently, ACSL3 can induce cells to develop ferroptosis resistance. In contrast, ACSL4 is a positive regulator of ferroptosis. In a study, Sebastian et al. found that in ACSL4 KO cells, lipid peroxidation was not detected even when cells were treated with RSL3, indicating that ACSL4 can promote ferroptosis (119). Phosphatidylethanolamine (PE), containing arachidonic acid (AA) and adrenic acid (AdA), was found to be the preferred substrate for oxidation by lipidomics approach, catalyzting the formation of Acyl-CoA, and then activates the corresponding fatty acids for lipid peroxidation (119, 120). Furthermore, ACSL4 levels are elevated in the livers of NAFLD patients, thereby promoting the fatty acid β-oxidation capacity of hepatocytes with a goal to reduce fat buildup (121). And studies have found that inhibition of fatty acid β-oxidation can induce ferroptosis (122). These findings suggest that ACSL4 can regulate ferroptosis through fatty acid β-oxidation. Due to the different catalysis of ACSL3 and ACSL4 within cells, they play opposite roles in ferroptosis.

MBOAT family is a group of genes that encode proteins playing crucial roles in lipid metabolism (123). These enzymes are involved in various aspects of lipid processing and modification within cellular membranes. According to the latest studies, MBOAT1 and MBOAT2 can inhibit ferroptosis (124). Jiang et al. (124) used genome-wide CRISPR activation screening technology to demonstrate that MBOAT1 and MBOAT2 can selectively convert MUFAs into lyso-phosphatidylethanolamine (lyso-PE), thereby reducing the content of intracellular PUFAs. Moreover, MOBAT1 and MOBAT2 are directly regulated by sex hormones. This discovery not only provides a new target for regulating ferroptosis, but also suggests that sex hormones play an essential role in ferroptosis.

LPCAT is one of the most important enzymes for maintaining phosphatidylcholine (PC) homeostasis. In fact, LPCAT is a subtype of enzyme in the MBOAT family (123). It controls phospholipid fatty acyl composition by catalyzing lysophospholipid sn-2 reacylation (125). Currently, four varieties of LPCAT have been described in the literature: LPCAT1, LPCAT2, LPCAT3, LPCAT4. Lpcat3’s role in lipid metabolism is by far the most evident. LPCAT3 is widely distributed in the human liver, intestines, and adipocytes (126, 127). LPCAT3 can regulate intestinal lipid absorption, lipoprotein secretion, and liver fat synthesis to maintain systemic lipid homeostasis. In a 2018 study, researchers found that knockdown of LPCAT3 in 3T3-L1 preadipocytes can reduce levels of polyunsaturated phospholipids and reduce the expression of genes related to fat production (128). In subsequent years, people began to pay attention to whether LPCAT3 has a regulatory effect on ferroptosis due to the antioxidant properties of polyunsaturated phospholipids. In 2022, Benjamin F Cravatt et al. (129) found that inhibiting the expression of LPCAT3 can inhibit the occurrence of ferroptosis. Researchers discovered in a recent study that LPCAT3 can promote the esterification of PUFAsinto phospholipids, provide raw materials for lipid peroxidation, and then promote ferroptosis (130). Furthermore, it has been established that ZEB promotes LPCAT3 transcription in a YAP-dependent manner (130). And YAP can also modulate the expression of the ACSL4 ( 131). The above research results suggest that regulating the expression of LPCAT3 and ACSL4 by targeting YAP expression, thus regulating ferroptosis, may be of great value in disease treatment.

Since its discovery in 1979, P53, a tumor suppressor gene, has been extensively studied for its role in tumors. P53 is essential for maintaining genome integrity, modulating cell cycle, and inhibiting angiogenesis (132, 133). In the past period, academics have discovered that P53 can regulate not only cell necrosis (134), apoptosis (135), and autophagy (136), but also ferroptosis (137). Complex signaling pathways are involved in the regulation of P53 on ferroptosis, and the results of distinct signaling pathways are inconsistent.

Already in 2015, researchers found that P533KR, a P53 acetylation deficient mutant, lost the function of regulating cell cycle, aging and apoptosis, but retained its tumor inhibitory function and the ability to regulate the expression of metabolic targets. It can inhibit cystine uptake and make cells sensitive to ferroptosis by inhibiting the transcription of SLC7A11 (a component of cystine/glutamate reverse transporter) (15). In recent years, it has also been discovered that P53 can block the expression of SLC7A11 in conditions such ovarian cancer (138) and acute lung injury (139). In the metabolism of polyamines, SAT1 (spermidine/spermine N1-acetyltransferase 1) plays a key role. According to Ou et al. (113), SAT1 deletion can prevent P53-mediated ferroptosis. Mechanistic analysis reveals that SAT1 induces ALOX15 expression to enhance ferroptosis (113). Additionally, P53 can control ferroptosis via ALOX12 (114). However, the specific regulatory mechanism has not been further explored. In a recent study, researchers found that vitamin K epoxide reductase complex subunit 1 like 1 (VKORC1L1) is a direct transcriptional target for P53 (140). The VKORC1L1 enzyme facilitates the synthesis of vitamin K hydroquinone, which is a completely reduced variant of vitamin K that effectively removes lipid peroxides (140, 141). And P53 promotes ferroptosis by inhibiting the expression of VKORC1L1 ( 140). Glutaminase 2 (GLS2) is a key enzyme in the catabolism of glutamine. Under the action of GLS2, glutamine is hydrolyzed into glutamic acid. In 2010, researchers discovered that GLS2, as the target gene of P53, can increase the content of GSH in cells and reduce the level of ROS, thereby protecting cells from oxidative stress damage (142, 143). The role of GLS2 in ferroptosis was not considered at the time because the phenomenon of ferroptosis had not yet been discovered. Interestingly, however, in 2015, researchers found that downregulation of GLS2 could inhibit ferroptosis induced by total amino acid or cystine deprivation (35). Moreover, Suzuki et al. (144) found that both GLS2-knockout mouse models and GLS2-deficient hepatocellular carcinoma cells confer significant resistance to ferroptosis. Further study of the mechanism found that GLS2 increases the generation of lipid ROSby promoting the conversion of glutamate to α-ketoglutarate, thereby promoting ferroptosis (144). Obviously, the conclusions of previous studies on the role of GLS2 in ferroptosis are contrary to the conclusions of recent studies. This phenomenon is worth pondering, and further research is needed to explain this paradox in the future.

The above described P53 positive regulation of ferroptosis related pathways, and then P53 expression can also inhibit the sensitivity of ferroptosis. In a 2019 study, Laura D et al. (145) used CRISPR/Cas9 genome editing, small molecule probes, and high-resolution time-lapse imaging techniques to find that P53 delays the response of cystine deprivation to ferroptosis through transcriptional regulation of P21. Therefore, the role of P53-P21 signal axis in ferroptosis was clarified. Subsequently, Venkatesh et al. (146) demonstrated again in tumor cells that unstable p53 inhibits the activity and expression of GPX4 by inhibiting p21 protein. In addition, P21 can also regulate ferroptosis independently of P53 ( 147). In colorectal cancer, P53 regulates ferroptosis by regulating the subcellular localization of dipeptidyl-peptidase-4 (DPP4) protein. P53 is able to prevent the nuclear accumulation of DPP4. In the absence of P53, DPP4 localizes to the plasma membrane and forms a complex with NADPH oxidase 1 on the plasma membrane, thereby increasing lipid peroxidation and iron deposition (148).

Regulation of ferroptosis by p53 is highly context-specific. Although current studies have shown that P53 plays an important role in regulating ferroptosis, the specific molecular mechanisms and interrelationships still need further exploration.

GPX4, which utilizes reduced GSH as a cofactor to detoxify lipid peroxides as lipid alcohols, thereby inhibiting ferroptosis, is one of the most notable defence mechanisms that cells have evolved to metabolise hazardous lipid peroxides (13). In addition, system x- c, which plays a core role in providing raw materials for the biosynthesis of GSH in cells, is also of concern (149). Therefore, GPX4 and SLC7A11 play a central role in resistance to ferroptosis.

GSH is a tripeptide found in all mammalian tissues, notably the liver, and is composed of glutamic acid, cysteine, and glycine held together by peptide bonds. Glutamate, cysteine and glycine are synthesized in the cytoplasm of liver cells under the catalysis of glutamate cysteine ligase (GCL) and glutathione synthase (GS) (150). GSH is the most abundant antioxidant in organisms, most of which are distributed in the cytoplasm, and a small part is distributed in the mitochondria and endoplasmic reticulum (151). There are two forms of glutathione in the human body: thiol-reduced (GSH) and disulfide-oxidized (GSSG) (152). Under normal circumstances, the content of GSSH in the human body is very low, and GSH mainly plays an antioxidant role.

GSH is essential for GPX4-catalyzed reactions. There are 8 kinds of GPX4 proteins in mammals, but only GPX4 has the effect of resisting lipid peroxidation (153). GPX4 is a selenocysteine-containing and glutathione-dependent enzyme. By means of GSH, it can catalyze the conversion of particular lipid hydroperoxides into lipid alcohols.

Selenocysteine is the active site of GPX4, and selenocysteine shuttles back and forth between the reduced state (Se-H) and the oxidized state (Se-OH) to complete the biological function. This process is mainly divided into three steps: First, the reduced GPX4(GPX4-Se-H) is oxidized to the oxidized GPX4(GPX4-Se-OH) by lipid peroxides, which are reduced to the corresponding alcohols; Then, GPX4-Se-OH is reduced by the reducing substrate GSH to generate selenium- glutathione adduct (GPX4-Se-SG); Finally, GPX4-Se-SG reacts with GSH again, transforms into GPX4-Se-H, and produces GSSH (13, 153). After the cycle described above, GSH as an electronics body, toxic lipid peroxides are converted into benign alcohols, so GPX4 is known as the gatekeeper of ferroptosis and plays an imperative part in suppressing lipid peroxidation. Finally, electrons are provided by NADPH, and GSSH is reduced to GSH under the catalysis of glutathione reductase (GR). The process of ubiquitination and dephosphorylation of GPX4 has also been found to facilitate the initiation of ferroptosis (154, 155).

The synthesis of GSH requires cysteine, and cysteine itself also has reducibility (156). However, extracellular cysteine is highly unstable and rapidly oxidised to cystine (the oxidised dimer form of cysteine) owing to the high level of oxidation in the extracellular environment. Therefore, most cells need cystine transporter system x- c to transport extracellular cystine to the intracellular synthesis of GSH.

The system x- c consists of two subunits connected by a disulfide bond, the light chain subunit SLC7A11 (also commonly known as xCT) and the heavy chain subunit solute carrier family 3 member 2 (SLC3A2) respectively. SLC7A11 is a 12-transmembrane protein with both N- and C-termini inside the cell (157). SLC7A11 is highly specific for cystine and glutamate, and is responsible for the main transport work, importing cystine into the cell at a ratio of 1:1 and exporting glutamate outside the cell (149). SLC3A2 is a single transmembrane protein (157), as a chaperone, it is critical to maintain the stability and membrane localization of SLC7A11 protein (158, 159). The cystine transported into the cell is reduced to cysteine by NADPH providing electrons, and then participates in the synthesis of GSH (160). Therefore, the overexpression of SLC7A11 in tumour cells can stimulate GSH synthesis and result in ferroptosis resistance (15). Figure 2 shows the role of SLC7A11 in GSH synthesis, and the metabolic process of GSH and GPX4 in cells.

The prevailing perspective in the early stages of research was that GPX4/GSH played a significant role as the primary mechanism for monitoring and regulating ferroptosis. Nevertheless, as research progresses, it has become evident that the responsiveness of various cancer cell lines to GPX4 inhibitors exhibits significant variability (161). This observation implies the existence of other variables that govern the susceptibility of cells to ferroptosis. To verify this result, Sebastian Doll et al. (162) extracted a cDNA expression library from the ferroptosis-resistant cell line MCF7 and screened complementary genes for GPX4 deletion, thereby identifying FSP1 as an unidentified anti-ferroptosis gene. Subsequent investigation has revealed that myristoylation of FSP1 is seemingly required for its anti-ferroptotic function (162). Myristoylation facilitates the recruitment of FSP1 to the plasma membrane (163). Once localized, FSP1 employs NAD(P)H to facilitate the catalytic regeneration of non-mitochondrial coenzyme Q10 (CoQ10). Ultimately, FSP1 mediates the prevention of ferroptosis by means of CoQ10 (162). In 2019, a groundbreaking discovery was made by researchers, revealing the coordination between the NAD(P)H-FSP1-CoQ10 axis and NAD(P)H-GPX4-GSH in the regulation of ferroptosis (162, 163). Furthermore, in recent years, scholars have made significant progress in the development of diverse small molecule inhibitors targeting FSP1 ( 162, 164). This achievement has laid a solid foundation for the potential utilization of FSP1 as a promising therapeutic approach for various diseases.

ROS are residual products of aerobic metabolism in the organism, including superoxide anion(O₂ ^–), hydroxyl radicals (•OH), peroxyl free radical (ROO•), hydrogen peroxide (H₂O₂) and singlet oxygen (¹O₂). ROS are produced primarily by mitochondrial metabolism (165) and NADPH oxidase on the cell membrane (166). Appropriate levels of ROS are crucial signaling molecules that play essential roles in signal transduction (167), cellular immune function (168), cell proliferation and cell repair (169). Nonetheless, excessive levels of ROS are toxic, triggering DNA damage (170), inflammatory responses (171), and cell death (172). Lipids dominated by PUFAs are oxidized many times by ROS to produce lipid peroxide, which leads to ferroptosis (13). Therefore, reducing intracellular ROS sources has become a strategy for disease treatment. Finally, as shown in Figure 3 , we summarized the mechanism and process of ferroptosis.