Cuproptosis: a novel therapeutic mechanism in lung cancer

Abstract

Background

Lung cancer, one of the most prevalent and deadly malignant tumors, is increasingly common globally in terms of both morbidity and mortality rates. Unlike pyroptosis and necroptosis, cuproptosis is a non-apoptotic programmed cell death process. Studies have demonstrated that cuproptosis is involved in the incidence, development, and metastasis of lung cancer. However, the mechanisms underlying cuproptosis in lung cancer remain to be fully elucidated.

Purpose

In this work, we primarily examine the most recent research on copper homeostasis, cuproptosis mechanisms, and the connection between lung cancer and cuproptosis.

Methods

A comprehensive literature search was conducted using the Web of Science, PubMed, and Google Scholar databases. The search strategy employed a combination of the keywords “cuproptosis” and “lung cancer.” The results encompassed publications from January 2020 to May 2025. This study aimed to gather research focusing on the relationship between lung cancer and cuproptosis, as well as the anticancer effects of drugs that induce cuproptosis.

Results

Our research indicates that lung cancer patients experience disruptions in copper ion homeostasis, as well as inhibition of cuproptosis, which points to a potentially effective therapeutic avenue through the induction of cuproptosis in lung cancer cells. This paper provides an overview of the mechanisms that highlight proteins associated with copper homeostasis and genes that play a role in cuproptosis in the lung cancer context. The modulation of proteins such as CTR1, ATOX1, FDX1, CCS, COX17, ATP7A, and ATP7B, in addition to LIPT1 and various long non-coding RNAs (AL691432.2, AC093010.2, AC107464.3, COLCA1, AC026471.3, LINC01833, and ITGB1-DT), along with genes such as DβH, LOXL2, SOD1, UBE2D1, and UBE2D3, can affect these mechanisms. These elements are vital for evaluating clinical interventions for lung cancer patients, predicting risks, and recognizing drug resistance. Moreover, we identified that pharmaceuticals facilitating copper ion transport (elesclomol and disulfiram), copper-chelating agents (DPEN, ATTM, and TETA), and nanoparticles engineered to transport copper are capable of effectively adjusting copper ion concentrations in lung cancer cells, subsequently inducing cuproptosis as a prospective treatment strategy for lung cancer. Furthermore, our findings suggest that lung cancer cells might counteract the harmful impacts of copper buildup by modulating proteins linked to copper metabolism, bolstering the antioxidant defense mechanisms, altering metabolic pathways, and triggering cellular stress responses and repair mechanisms.

Conclusion

Cuproptosis represents a novel mechanism dependent on copper that has important implications for the treatment of lung cancer. This process primarily involves the buildup of copper ions, which leads to a disruption in protein homeostasis, ultimately resulting in cell death. Additionally, the abnormal expression of crucial regulatory genes, such as FDX1 and LIPT1, along with transport proteins like CTR1 and ATP7A/B, is closely linked to the advancement of lung cancer. At present, drugs that act as carriers for copper ions (such as elesclomol and disulfiram), metal-organic frameworks based on copper, and copper chelators (including D-penicillamine and ammonium tetrathiomolybdate) have demonstrated promise in eliciting copper-mediated cell death in lung cancer cells. These discoveries suggest new potential targets and strategies for treating lung cancer, which could enhance the prognosis for patients diagnosed with the disease.

Graphical abstract

Introduction

The most common cause of cancer-related mortality globally is lung cancer, a malignant tumor of the respiratory system [1, 2]. It may be separated into small cell lung cancer (SCLC) and non-small cell lung cancer (NSCLC) based on its pathologic categorization [3]. With the aging of the global population, lung cancer is seriously affecting human health worldwide. As to GLOBOCAN’s projection, China is expected to witness around 871,000 new instances of lung cancer and 767,000 new deaths from the disease in 2022, which represents 18.1% and 23.9% of the overall cancer incidence and deaths, respectively. The incidence and death of lung cancer accounted for 18.1% and 23.9% of the total cancer cases respectively [4]. Despite new advances in the treatment of lung cancer, the therapeutic effect is still unsatisfactory due to metastasis, recurrence, and resistance to chemotherapeutic drugs [5–8]. Therefore, there is an urgent need to better understand and develop more therapeutic mechanisms for lung cancer.

Recently, in addition to the traditional modes of cell death (apoptosis [9, 10], pyroptosis [11, 12], autophagy [13, 14], ferroptosis [15, 16], etc.), Tsvetkov et al. [17] have identified a new cell death pathway called cuproptosis This mechanism is dependent on mitochondrial respiration and copper ions bind directly to lipid components of the tricarboxylic acid (TCA) cycle, leading to aggregation of fatty acylated proteins and loss of iron-sulfur cluster proteins, which in turn induces proteotoxic stress and ultimately cell death [18]. The imbalance of copper plays an important role in the occurrence and progression of cancer in vivo [19]. Recent studies have found that higher copper levels in lung cancer patients are closely associated with tumor generation, progression, and metastasis [20]. In addition, serum copper ion concentrations were linked to a worse clinical prognosis in patients with lung cancer, and copper ion concentrations were greater in patients with lower clinical stages [21]. As a result, it is anticipated that cuproptosis will provide a novel therapeutic target for the management of lung cancer. In this paper, we reviewed the latest findings on copper homeostasis, cuproptosis mechanism, and cuproptosis and lung cancer, and explored the role of cuproptosis related genes and copper homeostasis-related proteins in lung cancer, with a view to developing new targeted drugs for lung cancer treatment and providing new reference basis for the treatment and prognosis of lung cancer patients.

Literature search strategy

A literature search was conducted in Web of Science, PubMed, and Google Scholar databases. A search strategy combining the keywords “cuproptosis” and “lung cancer” was used. The search results covered publications from January 2020 to May 2025. The study aimed to collect research on the association between lung cancer and cuproptosis, as well as on the anticancer effects of drugs in inducing cuproptosis.

Copper homeostasis

To maintain the organism’s normal physiological function, the intracellular copper concentration must be kept within a relatively narrow range [22, 23]. The occurrence of cuproptosis is predicated on the organism’s metabolic disorders causing excessive intracellular copper accumulation that is not metabolized in a timely and effective manner, resulting in copper in the cells [24]. Copper transporter proteins, chaperone proteins, and enzymes work in concert to maintain intracellular copper homeostasis, which is a complicated and strictly controlled process [25] (Fig. 1). copper transporter 1 (CTR1), copper-transporting ATPase, and copper chaperone proteins are all directly involved in the preservation of intracellular copper homeostasis.

Fig. 1.

Regulation mechanism of copper homeostasis

STEAP is responsible for the reduction of Cu²⁺ to Cu⁺. CTP1 is mainly responsible for the transmembrane uptake of extracellular Cu⁺. ATOX1 is responsible for the intracellular transport of Cu⁺. When the intracellular Cu⁺ is too high, ATOX1 transports Cu⁺ to the TGN via ATP7A/B to promote the efflux of Cu⁺. CCS is responsible for the transfer of Cu⁺ to SOD1. COX17 is responsible for the transporter of Cu⁺ to the mitochondria. which provides Cu⁺ to COX11 and SOD1.

CTR1

A member of the CTR family, CTR1 is primarily in charge of transmembrane absorption of extracellular Cu⁺ [26]. In order to allow copper ions to flow through the plasma membrane, it has been demonstrated that CTR1 proteins are mostly structured in the shape of a trimer in the cell membrane as a pore created by stacking nine helical transmembrane peptides [27]. The majority of extracellular copper exists as Cu²⁺, which is converted to Cu⁺ by cell surface reductases (such as those in the STEAP family) prior to being absorbed by the cell [28]. CTR1 subsequently facilitates the absorption of Cu⁺ into the cell. The expression level of CTR1 protein directly affects the balance of copper homeostasis in vivo and is one of the primary transport proteins for the transmembrane absorption of copper ions by the cell [29]. In vitro experiments have shown that the expression of CTR1 is regulated by the level of copper: a low level of Cu²⁺ inhibits the expression of CTR1 to prevent copper cytotoxicity, and an increase in the extracellular uptake of Cu²⁺ is achieved by up-regulating the expression of CTR1 protein, and a decrease in the extracellular level of Cu²⁺ inhibits the expression of CTR1 [30, 31]. Consequently, CTR1 plays an important role in maintaining copper homeostasis.

Copper chaperones

In order to mediate many physiological processes, copper that enters a cell by Cu⁺ first binds to copper chaperone proteins in the cytoplasm before being transported to other cellular compartments, including the cytoplasm, mitochondria, trans-Golgi network (TGN), and nucleus [32]. Three primary copper chaperones have been found in mammalian cells: copper chaperone for superoxide dismutase 1 (CCS) [33], antioxidant 1 (ATOX1) [34], and cytochrome c oxidase copper chaperone (COX17) [35].

ATOX1

Mainly located in the cytoplasm and nucleus of cells, ATOX1 is an intracellular copper chaperone protein that regulates and transports copper ions [36]. The intracellular copper chaperone protein ATOX1 is in charge of moving and controlling copper ions. Cu⁺ that CTR1 takes up into the cytoplasm binds to ATOX1 and travels to the TGN, where it binds to the conserved N-terminal sequence of ATP7A and ATP7B in the TGN, GMTCXXC [37]. Through ligand exchange, Cu⁺ is transported to ATP7A and ATP7B, and it also encourages the synthesis of copper enzymes, including lysyl oxidase (LOX) and copper blue protein (ceruloplasmin, CP), which in turn mediates the excretion of excess copper ions from cells [38]. For instance, these copper ion transporters pump Cu⁺ from the cytoplasm into the TGN lumen at normal cell copper ion levels; These transporters will be moved from TGN to the vesicle compartment as the intracellular copper ion level rises, where they will fuse with the plasma membrane to produce Cu⁺; Copper will be pumped back to TGN after levels reach normal physiological levels [39]. Consequently, ATOX1 plays a critical role in preserving intracellular copper ion homeostasis and is primarily in charge of the cell’s copper ion secretion route.

CCS

CCS is a soluble copper chaperone protein with three domains; structural domain 1 contains the CXXC sequence of the site for binding copper ions [40]; structural domain 2 has a structure similar to that of superoxide dismutase 1 (SOD1) and has the role of specifically recognizing SOD1 and assisting structural domain 1 in the delivery of copper ions to SOD1 [41]; and structural domain 3 has the role of binding copper ions and transferring them to SOD1 [42, 43]. A significant antioxidant enzyme called SOD1 catalyzes the transformation of superoxide radicals into oxygen and hydrogen peroxide, preserving the balance of reactive oxygen species and shielding cells from the damaging effects of oxidative stress [44]. To preserve copper homeostasis, CCS in the cytoplasm can move Cu⁺ to SOD1’s copper-binding site. As a copper chaperone protein for SOD1, CCS is influenced by copper ions, and its expression is controlled by the concentration of copper ions inside cells; the greater the concentration of copper ions, the more CCS is present, and the lower the concentration of copper ions, the more CCS degradation occurs [45, 46]. Furthermore, SOD1 sensitivity rose and SOD1 activity reduced in vivo when CCS gene mice were knocked out, indicating that CCS is an important mechanism by which SOD1 obtains Cu⁺ [47]. Therefore, CCS can maintain the homeostasis of intracellular copper and reactive oxygen species, thus avoiding oxidative damage caused by copper overload.

COX17

Mainly present in the cytoplasm and the mitochondrial membrane space, COX17 is an essential copper chaperone protein in mitochondria [48]. It is the transporter of Cu⁺ to mitochondria and takes part in the assembly of copper ions from copper-binding proteins in mitochondria [49, 50]. COX17 binds to Cu⁺ and transports it from the cytoplasm to the inner mitochondrial membrane. Subsequently, COX17 delivers Cu⁺ to COX11 and SCO1, important components of COX assembly [51]. COX11 is located in the mitochondrial intermembrane space and mediates the assembly of copper ions to the CUB binding site of the COX1 subunit, while SCO1 in the mitochondrion assembles copper ions to the CUA binding site of the COX2 subunit, which activates cytochrome c oxidase (CCO) [52]. As a result, COX17 is crucial for the normal assembly of COX and serves as a key copper donor for COX11 and SCO1, with the ability to activate CCO.

Copper-transporting ATPases

Copper-transporting ATPases (Cu-ATPases) are a class of metal ion-transporting proteins distributed in the plasma membrane [53–55]. Among them, ATPase copper-transporting α (ATP7A) and ATPase copper-transporting β (ATP7B) proteins are highly conserved transmembrane proteins of the ATPase family, whose main function is to induce ATP hydrolysis by binding to Cu⁺ to provide energy for transporting excess copper ions out of the cell membrane [56]. ATP7’s primary job is to attach to copper and cause ATP hydrolysis, which releases energy for the movement of extra copper ions out of the cell membrane [57, 58]. Copper ions are transported by ATP7A and ATP7B to the TGN and other cellular compartments for a variety of cellular functions under normal circumstances [59]. ATP7A and ATP7B are triggered when intracellular copper levels become too high [60]. They export excess copper ions from the TGN and store them in copper-binding proteins, such as metallothionein, before recycling them back to the TGN when copper levels return to normal. These proteins mainly control intracellular copper homeostasis by enhancing efflux and reducing absorption [61]. Thus, ATP7A and ATP7B are primarily associated with the efflux of intracellular copper ions and are key regulators in the maintenance of intracellular copper homeostasis.

In conclusion, the copper transporter protein CTR1 is primarily responsible for the uptake of extracellular copper ions; the copper chaperone proteins ATOX1, CCS, and COX17 are primarily responsible for the secretion and utilization of intracellular copper ions; and ATP7A and ATP7B are primarily responsible for the efflux of intracellular copper ions. Thus, the balance of intracellular copper homeostasis is maintained by the combined actions of CTR1, ATOX1, CCS, COX17, ATP7A, and ATP7B in the intake, transport, use, and outflow of copper ions (Table 1).

Table 1.

Function of copper homeostasis associated proteins

Protein	Full name	Subcellular locations	Functions
CTR1	Copper transporter 1	cytomembrane	Intake of extracellular Cu+
ATOX1	Antioxidant 1	Cytoplasm and nucleus	Combined with Cu+ and transported to the trans-Golgi network
CCS	Copper chaperone for superoxide dismutase 1	Cytoplasm	Transfer Cu+ to the copper binding site of SOD1
COX17	Cytochrome c oxidase copper chaperone	Cytoplasm and mitochondrial membrane	Combined with Cu+ and transported to the mitochondrial inner membrane, participating in the assembly of COX
ATP7A/B	ATPase copper-transporting α/β	Cytoplasm	Transport Cu+ to TGN and transport excess Cu+ to the outside of the cell

Cuproptosis and other forms of programmed cell death

Regulatory mechanisms of Cuproptosis

Copper is a vital trace element that plays a crucial role in numerous biological processes [62]. It functions as a cofactor in the active sites of several important enzymes including cytochrome c oxidase (part of the electron transport chain complex IV), copper-zinc superoxide dismutase (Cu/Zn-SOD), dopamine β-hydroxylase, and ceruloplasmin [63]. These enzymes that contain copper are significantly involved in essential physiological functions in the body, such as mitochondrial energy production, the elimination of reactive oxygen species, the regulation of apoptosis, and the upkeep of cellular viability [64]. Regarding its absorption and metabolism, the primary regions for copper ion uptake are the duodenum and jejunum, while the liver serves as the principal storage organ for copper within the body [65]. Excess copper is excreted into the intestine through bile, and is ultimately removed from the body via feces [66]. Furthermore, a minor quantity of copper can be secreted through the gastrointestinal mucosa or eliminated via urine by the kidneys [67] This intricate balance of copper ions, upheld by precisely controlled mechanisms of absorption, transport, and excretion, is known as copper homeostasis [68]. It is important to maintain intracellular copper concentrations within appropriate physiological limits; imbalances such as copper deficiency or overload can result in cellular dysfunction [69]. Recent research has demonstrated that disruptions in copper homeostasis are strongly linked to the onset and progression of various pathological conditions, including neurodegenerative diseases, metabolic disorders, and malignant tumors [70, 71]. The management of copper homeostasis is intricate; when copper ion levels surpass a certain threshold, they can induce cytotoxic effects and excessive respiration, leading to cell death. Key components involved in copper homeostasis include CTR1, ATOX1, CCS, COX11, COX17, ATP7A, and ATP7B.

Cuproptosis represents a new type of cell death that relies on copper and was introduced by Tsvetkov. This mechanism is distinct from previously recognized forms of cell death, including apoptosis, pyroptosis, necrosis, autophagy, and ferroptosis (Table 2) [72–75]. A fundamental characteristic of this process is its dependence on energy, specifically requiring a steady supply of adenosine triphosphate (ATP), which is facilitated by the targeted action of copper ions on mitochondrial metabolic pathways [76]. Research indicates that the selective accumulation of copper ions in the mitochondria initiates a cascade reaction by interacting with acylated metabolic enzymes involved in the TCA cycle [77–79]. This conserved post-translational modification on lysine residues can profoundly impact the biological roles of four essential enzymes within the TCA cycle. In particular, copper ions induce abnormal oligomerization of acylated proteins and inhibit the synthesis of iron-sulfur (Fe-S) proteins, which ultimately disrupts protein homeostasis and leads to cell death. At the molecular level of regulation, ferredoxin 1 (FDX1) plays a crucial role in apoptosis, facilitating the acylation of dihydrolipoamide S-acetyltransferase (DLAT) by reducing Cu²⁺ to Cu⁺, thereby inducing cell death through a decrease in the levels of iron-sulfur (Fe-S) clusters [80]. Genetic investigations have demonstrated that the loss of the FDX1 gene significantly reduces protein acylation levels, effectively preventing copper-induced cell death [81]. Additionally, lipoic acid synthase (LIAS), a key enzyme in the acylation modification pathway, also reduces the copper metabolic process when knocked out [82, 83]. Importantly, the simultaneous knockout of both FDX1 and LIAS results in the degradation of iron-sulfur cluster proteins that serve as copper carriers, causing significant disruptions in protein homeostasis and leading to cell death [84]. DLAT, recognized as a typical acylated protein [85], interacts with divalent copper ions (Cu²⁺), leading to three significant effects: (1) a reduction in the stability of iron-sulfur cluster proteins; (2) stimulation of abnormal protein oligomerization; and (3) increased reducing activity of copper ions. Collectively, these alterations result in disruptions of TCA cycle metabolism, evident through abnormal aggregation of acylated proteins and a decline in iron-sulfur cluster protein levels, ultimately causing cell death via protein toxicity stress pathways [86, 87]. Thus, the intracellular buildup of copper ions constitutes a primary mechanism by which copper ion carriers promote apoptosis. The proteins CTR1, ATOX1, CCS, COX17, ATP7A, and ATP7B play crucial roles in maintaining cellular copper homeostasis. Following overexpression of SLC31A1 (known as CTR1) in HEK293T cells, Tsvetkov discovered that these cells became increasingly vulnerable to the effects of physiological copper ion concentrations, and employing copper ion chelators could avert cell apoptosis. Additionally, intracellular copper chaperone glutathione levels further decreased with the use of glutathione synthase inhibitors, resulting in apoptosis. Lastly, research using an ATP7B-deficient mouse model showed that, in comparison to wild-type mice, the expression of heat shock protein 70 (HSP70) increased, while both the accumulation of acetylated proteins and iron-sulfur cluster protein levels diminished, creating a disruption in cellular copper homeostasis that led to copper accumulation and elevated cellular copper concentrations [17]. These observations provide substantial evidence for comprehending the pathological damage resulting from copper homeostasis imbalances (Fig. 2). In summary, the intracellular copper overload induced by disorders in copper metabolism is the fundamental cause of cuproptosis, and this finding reveals new molecular targets for treating associated diseases.

Table 2.

Biological differences in programmed cell death modes

Type	Morphological characteristics	Biochemical characteristics	Main regulatory factors
Apoptosis	Cell volume shrinks, apoptotic bodies form, cytoskeleton collapses, and mitochondrial membrane potential disappears	Caspase-dependent, Bax/Bcl-2 mediated formation of mitochondrial outer membrane permeable oligomers	Positive regulation: Bax Negative Regulation: Bcl-2、p53、caspase-3/7/8/9
Necroptosis	Cell swelling, rupture of cell membrane, release of cellular contents, and infiltration of inflammatory cells	Caspase-independent, RIPK1/RIPK3 mediated MLKL phosphorylation and assembly of necrotic bodies	Positive regulation: RIPK1、RIPK3、MLKL Negative Regulation: AURKA
Pyroptosis	Cell swelling, formation of pores on the cell membrane, foaming and rupture of the plasma membrane, and release of cytoplasmic contents	Caspase-dependent, GSDMD cleavage, inflammasome formation, IL-18 and IL-1 β release	Positive regulation: CASP1、CASP4、CASP5、CASP11、GSDMD Negative Regulation: GPX4
Autophagy	Autophagosomes form and encapsulate damaged organelles or proteins within cells. Autophagosomes fuse with lysosomes to form autolysosomes, and organelles and cytoplasm are degraded.	Caspase-independent, LC3 lipidation, autophagosome formation, increased autophagic flux, and lysosomal activity	Positive regulation: AMPK、ULK、VPS34 Negative Regulation: mTOR
Ferroptosis	Cell swelling, formation of pores on the cell membrane, mitochondrial shrinkage, reduction of mitochondrial cristae, and increase in mitochondrial membrane density	Caspase-independent, iron accumulation, lipid peroxidation, System Xc -/GSH/GPX4 pathway inhibition	Positive regulation: TFRC、ALOX、ACSL4、LPCAT3 Negative Regulation: GPX4、AIFM2
Cuproptosis	Cell volume shrinks, mitochondrial membrane and cell membrane rupture, nuclear shrinkage, and chromatin rupture	Copper-dependent, acylation protein aggregation, and loss of Fe-S cluster cluster	Positive regulation: FDX1、SLC31A1 Negative Regulation: ATP7A、 ATP7B、COX17

Fig. 2.

Regulatory mechanism of cuproptosis

Regulatory mechanisms of programmed cell death in other cells

Apoptosis

The process of programmed cell death, known as apoptosis, is a biological event that is tightly controlled by genetic mechanisms. This phenomenon is primarily distinguished by a reaction cascade that involves the cysteine protease family, commonly referred to as Caspases [88, 89]. Depending on the source of the triggering signals, apoptosis can be categorized into two pathways: the intrinsic pathway driven by mitochondria and the extrinsic pathway initiated by death receptors [90, 91]. Both pathways eventually lead to the activation of initiator Caspases, such as Caspase-8 and Caspase-9, which subsequently activate the effector Caspases-3 and − 7. By cleaving specific proteins, these Caspases degrade essential cellular structural elements, resulting in characteristic morphological alterations like blebbing of the cell membrane and margination of chromatin. This cascade culminates in the orderly dismantling of intracellular structures [92, 93].

Necroptosis

Programmed necrosis refers to a controlled form of necrotic cell death that displays both regulatory features and inflammatory reactions [94, 95]. This process is initiated when TNF-α attaches to TNFR1, subsequently bringing together the receptor’s intracellular domain to create complex I, which includes RIPK1, TRAF2, and cIAP1/2 [96, 97]. If the functionality of cIAP1/2 is compromised or if ubiquitination is blocked, then complex I re’organizes, resulting in the deubiquitination of RIPK1. This modified RIPK1 subsequently associates with FADD and procaspase-8 to form complex IIa [98]. Should there be any inhibition of caspase-8 activity, the phosphorylated RIPK1 activates RIPK3, which leads to the generation of necrosomes (complex IIb) [99]. The phosphorylation of RIPK3 facilitates multi-site phosphorylation of MLKL, causing a change in its conformation and leading to its oligomerization into a transmembrane pore, thereby compromising cell membrane integrity, releasing DAMPs, and initiating inflammatory responses [100, 101].

Pyroptosis

Pyroptosis represents a type of programmed necrosis that is driven by the inflammasome, which causes the perforation of cell membranes by cleaving gasdermin D (GSDMD) [102]. This process releases intracellular components and instigates inflammatory reactions. Pyroptosis can be categorized into two pathways: classical and non-classical [103, 104]. The classical pathway begins when pattern recognition receptors (NLR) detect signals indicating pathogens or cell damage, prompting the formation of the inflammasome, which consists of ASC and pro-caspase-1. Once caspase-1 is activated, it cleaves IL-1β/IL-18 and gasdermin D, allowing the N-terminal fragment of GSDMD to embed into the membrane and create pores, leading to cell lysis [105, 106]. Conversely, the non-classical pathway involves the direct interaction of LPS with the CARD domain of caspase-4/5/11, which activates GSDMD cleavage and similarly triggers membrane damage along with inflammatory responses [107]. Both pathways rely on proteins from the gasdermin family to facilitate membrane disruption, culminating in cell swelling, rupture of the plasma membrane, and the release of pro-inflammatory mediators [108, 109].

Autophagy

Autophagy serves as a mechanism for intracellular recycling that depends on lysosomes and is vital for maintaining cellular homeostasis by assisting in the degradation of dysfunctional protein aggregates and damaged organelles [110, 111]. When faced with nutrient limitation, stress, or hypoxic conditions, the activity of mTORC1 (mammalian target of rapamycin complex 1) decreases, leading to a reduction in its inhibitory effect on ULK1 kinase [112]. Concurrently, AMP-activated protein kinase (AMPK) enhances the assembly of the ULK1-FIP200-ATG13 complex by phosphorylating ULK1 at the Ser317 and Ser777 residues, which kickstarts the formation of the isolation membrane, also known as the autophagic precursor membrane [113]. The activated ULK1 complex recruits critical components of class III phosphatidylinositol 3-kinase (PI3KC3), including Beclin1 and VPS34, which aids in the production of phosphatidylinositol 3-phosphate (PI3P) [114, 115]. Consequently, this process draws in ATG5-ATG12-ATG16 and LC3-I, ultimately resulting in the formation of the autophagosome [116, 117]. The transition of LC3-I to its membrane-bound form, LC3-II, takes place through ATG4-mediated cleavage and a lipidation mechanism involving ATG7 and ATG3, indicating the maturation of the autophagosome [118, 119]. In the end, the autophagosome fuses with the lysosome to create the autolysosome, which degrades its contents and releases materials for recycling within the cell [120, 121].

Ferroptosis

Ferroptosis represents a form of programmed cell death that is non-apoptotic and reliant on iron, marked by disruptions in iron metabolism and damage to membranes driven by lipid peroxidation [122, 123]. The accumulation of intracellular iron produces ROS via the Fenton reaction and stimulates iron-containing enzymes like ALOX, which in turn enhances lipid peroxidation [124, 125]. The action of long-chain fatty acid-CoA ligase (ACSL4) and lysophosphatidylcholine acyltransferase (LPCAT) facilitates the transformation of polyunsaturated fatty acids (PUFAs) into phospholipid-polyunsaturated fatty acids (PUFA-PLs), which are subsequently converted into phospholipid hydroperoxides (PL-PUFA-OOH) by oxidizing agents such as ALOX. This series of reactions culminates in structural damage and reduced functionality of the cell membrane, ultimately initiating ferroptosis [126, 127].

SLC31A1 (CTR1) facilitates the intracellular uptake of Cu⁺, which is then carried to the mitochondria by COX17. FDX1 causes lipid acylation of DLAT and decreases Cu²⁺ to Cu⁺. Cu⁺ inhibits the production of Fe-S cluster and binds to lipid-acylated proteins in the tricarboxylic acid cycle (TAC), which causes the aggregation of lipid acylation-modified proteins. These actions together cause proteotoxic stress and, eventually, cellular cuproptosis.

Cuproptosis and lung cancer

As research on cuproptosis has progressed, it has been shown that copper buildup increases the development, angiogenesis, and spread of tumors. Additionally, copper concentrations in serum and many cancer tissues are much higher than those in normal tissues [128]. Thus, there is a connection between the growth of tumors and intracellular copper ion levels. Although its exact involvement in lung cancer is unknown, an increasing number of studies have discovered a strong correlation between the mortality rate of lung cancer patients and copper [129–131]. Therefore, novel treatment approaches for lung cancer patients may result from an understanding of the mechanism of cuproptosis in lung cancer from copper homeostasis-related proteins and genes connected to cuproptosis.

Copper homeostasis related protein and lung cancer

Copper homeostasis is essential for sustaining fundamental cellular activities [132, 133]. The absorption, transport, utilization, and efflux of copper ions in the body are closely associated with copper homeostasis-related proteins, including CTR1, ATOX1, CCS, COX17, ATP7A, and ATP7B. A meta-analysis indicated that the clinical stage in patients with lung adenocarcinoma is linked to higher concentrations of copper ions in the blood, which promote angiogenesis by activating various angiogenic factors such as HIF-1 and IL-8, ultimately leading to angiogenesis, growth, and metastasis [134]. CTR1 acts as a crucial regulatory protein for copper and exhibits elevated expression levels in breast, esophageal, and gastric cancers [135]. A study by Cao et al. suggests that the diagnostic effectiveness of carcinoembryonic antigen (CEA) for benign pulmonary nodules in NSCLC can be enhanced by combining anti-CTR1 autoantibodies IgG and IgM [136]. In a clinical data study, it was observed that patients with stage III NSCLC selected for platinum-based chemotherapy had their tumor tissues analyzed through immunohistochemistry experiments, which revealed that high expression of CTR1 correlated with improved therapeutic efficacy against cisplatin and a favorable prognosis [137]. Therefore, CTR1 is not only an independent predictor of response to platinum-based chemotherapy but also a prognostic factor for patients with stage III NSCLC, making it a potential new target for overcoming platinum-based drug resistance. An increasing body of research indicates that copper chaperonin plays a critical role in the development of lung cancer. Notably, COX17 is highly expressed in lung cancer patients, making its inhibition a promising therapeutic target [138]. Additionally, ATOX1 expression levels are significantly elevated in NSCLC tissues compared to normal tissues, and this upregulation is strongly correlated with patient survival and cancer metastasis [139, 140]. Evidence suggests that inhibiting ATOX1 and CCS disrupts intracellular copper ion transport, which directly reduces tumor cell proliferation [141]. Furthermore, ATP7A and ATP7B are pivotal in tumor progression, as they promote the synthesis of LOX family members, facilitating extracellular matrix remodeling essential for tumor cell migration [142]. Petri et al. [143] demonstrated that silencing ATP7A using CRISPR-Cas9 technology suppressed LOX activity, thereby inhibiting the progression and metastasis of lung cancer cells. SLC31A1, a key protein that regulates intracellular copper ion concentration and transports Cu⁺ to the extracellular compartment, is associated with ATP7B and the risk of lung adenocarcinoma, suggesting that lung cancer progression is influenced by the expression levels of both proteins [144, 145]. Li et al. [146] reported that the combination of disulfiram and JQ-1 (a PD-L1 inhibitor) upregulated the expression of FDX1 and SLC31A1 while downregulating ATP7B, SDHB, PD-L1, and HIF-1 A in A549 cells, thereby inducing cuproptosis in NSCLC cells. The normal functioning of copper homeostatic proteins, including CTR1, ATOX1, FDX1, CCS, COX17, ATP7A, and ATP7B, is crucial for maintaining intracellular copper ion homeostasis. When this balance is disrupted in lung cancer cells, the expression of copper homeostatic proteins is also altered. Consequently, manipulating their levels can induce cuproptosis in lung cancer cells, thereby inhibiting tumor progression.

Cuproptosis related genes and lung cancer

Cuproptosis currently demonstrates significant potential in the treatment of lung cancer [147–149]. The molecular characterization of genes associated with cuproptosis will enhance our understanding of the heterogeneity of lung cancer, which is vital for the diagnosis, prognosis, and treatment of lung cancer patients in clinical settings. One study indicated that LIPT1 expression was lower in NSCLC, and higher LIPT1 levels were correlated with a better prognosis for NSCLC patients. Lung cancer cells underwent cuproptosis and experienced growth inhibition when LIPT1 was overexpressed. Further research indicated that LIPT1 inhibited the growth of NSCLC by downregulating ATOX1 expression [150–152]. Consequently, LIPT1 has been identified as having an inhibitory effect on lung cancer by regulating ATOX1, positioning it as a potential predictive biomarker for NSCLC. Long non-coding RNA (lncRNA), an essential component of the non-coding genome, is defined as an RNA molecule longer than 200 nucleotides that does not code for proteins. Many cancers exhibit mutations or aberrant expression of lncRNAs [153, 154]. Some studies have shown that lncRNA levels in NSCLC patients are positively correlated with tumor size, metastasis, and stage [155]. Ma et al. [156] identified eight lncRNAs associated with cuproptosis by constructing CoCuLncSig, a clinical model for LUAD, and confirmed through qRT-PCR that seven genes exhibited differential expression in tumor and normal tissue samples: AL691432.2, AC093010.2, AC107464.3, COLCA1, AC026471.3, LINC01833, and ITGB1-DT. Higher expression levels of LINC01833 and ITGB1-DT in cancer tissues adversely affected the prognosis of LUAD, while AL691432.2, AC093010.2, AC107464.3, COLCA1, and AC026471.3 had a protective effect. Notably, LncRNA LINC01833 was significantly differentially expressed between tumor and normal tissues and demonstrated stronger prognostic potential in lung adenocarcinoma. Zhao et al. [157] found that AC253536.6 was highly expressed in lung cancer cells, while MIR3945HG, AC008972.2, and AC010328.1 were expressed at lower levels, as indicated by data from The Cancer Genome Atlas (TCGA) database. The subsequent construction of a prognostic prediction model demonstrated that these four cuproptosis-associated LncRNAs could serve as valuable indicators for assessing the prognosis of lung cancer patients. Consequently, the investigation of cuproptosis-associated LncRNAs is anticipated to yield new therapeutic targets and biomarkers in lung cancer research. Research findings indicate that LUAD tissues exhibited down-regulated DβH expression, whereas cuproptosis-associated genes LOXL2, UBE2D1, and UBE2D3 showed significantly higher expression levels compared to normal tissues. Additionally, a longer lifespan was associated with high DβH expression, but not with the low expression of LOXL2, SOD1, UBE2D1, or UBE2D3 [158].

The gene XBP1s, associated with endoplasmic reticulum stress, is recognized as an oncogene in lung carcinoma [159]. Findings by Gu et al. demonstrate that the overexpression of XBP1s leads to a reduction in the protein levels of LIPT1, which in turn inhibits cuproptosis in LUAD cells triggered by the copper ionophore elesclomol [160]. According to Xu et al., the circular RNA circKIAA1797 binds to FDX1 mRNA, decreasing its stability and thereby downregulating FDX1 expression. Additionally, circKIAA1797 binds to the protein signal transducer and activator of transcription 1 (STAT1), which suppresses LIPT1 transcription, consequently hindering cuproptosis in lung cancer cells. Moreover, circKIAA1797 facilitates the closure of the mitochondrial permeability transition pore (mPTP), which inhibits cuproptosis and ultimately promotes lung cancer progression [161]. Glutathione S-transferase (GST) serves as a detoxification enzyme primarily engaged in glutathione metabolism, contributing to the elimination of free radicals and peroxides, thus safeguarding cells against oxidative injury [162, 163]. GSTP1, part of the GST family, is overexpressed in a majority of tumor cells and correlates with negative prognoses in patients [164]. One study indicated that waterpipe tobacco smoking (WP) and genetic variations in GSTs might be associated with a heightened risk of developing lung cancer [165]. Research reveals that after exposure to a copper-zinc alloy, the expression levels of DLAT and ACO1 were elevated, while GR expression was increased and GST and GPx expressions diminished, suggesting that an excess of copper ions impairs the antioxidant defense system of glutathione (GSH), potentially resulting in copper-induced cell death [166]. Research conducted by Cina et al. indicates that NDT-05-1040 (a siRNA inhibitor of GSTP) can effectively diminish the phosphorylation activities within the MAPK and PI3K pathways in KRAS mutant NSCLC cells, thereby inhibiting the proliferation and inducing apoptosis of lung cancer cells [167]. Liu et al. [168] found that DARS2 expression was elevated in LUAD patients, as demonstrated through genomic analyses and in vitro experiments. They reported that down-regulation of DARS2 significantly inhibited tumor cell growth and reduced the infiltration of B cells and T follicular helper (Tfh) cells. The mechanism underlying this effect may be linked to the down-regulation of DLAT, which affects the imbalance of copper ions in LUAD, inducing cuproptosis and subsequently influencing the progression of LUAD. Additionally, a study examining cuproptosis-related gene polymorphisms in lung cancer patients and healthy individuals identified SLC31A1-rs10981694 and FDX1-rs10488764 as associated with an increased risk of lung cancer, while rs9535826 and rs9535828 in ATP7B were linked to a decreased risk. This finding highlights the relevance of cuproptosis-related genes in assessing lung cancer risk, providing a novel reference for early detection and diagnosis of the disease [144]. Consequently, genes such as LIPT1, various long non-coding RNAs (including AL691432.2, AC093010.2, AC107464.3, COLCA1, AC026471.3, LINC01833, and ITGB1-DT), XBP1s, cirKIAA1797, GST, DβH, LOXL2, SOD1, UBE2D1, and UBE2D3 emerge as potential candidate genes for lung cancer, serving as promising clinical biomarkers for diagnosis, treatment, and prognosis.

The interaction between cuproptosis and other cell death pathways in lung cancer

In recent years, advancements in tumor research have revealed that various types of programmed cell death are prevalent in lung cancer, with established connections among them. Both cuproptosis and ferroptosis contribute to cell lysis by facilitating the release of high levels of ROS, which damage cellular membranes. This process can effectively reverse the immunosuppressive conditions of the tumor microenvironment (TME) [169–171]. Studies indicate that the overexpression of reducing GSH and glutathione peroxidase 4 (GPX4) within the TME can readily eliminate ROS and lipid peroxides associated with ROS, thereby preventing the onset of ferroptosis and cuproptosis [17, 172]. Jiang et al. introduced a dual depletion strategy aimed at targeting GSH/GPX4 in tumor locales. Their findings demonstrated that Cu²⁺ in lung cancer cell lines with KRAS-TP53 mutations (KP cells) not only suppressed xCT expression via GSH but also directly led to the degradation of GPX4, triggering ferroptosis. Furthermore, it was established that Cu²⁺ primarily induces cuproptosis in lung cancer KP cells by reducing FDX1 expression levels [173]. Additionally, Gu et al. engineered a functional nanoenzyme system called CussOMEp, which corroborated that Cu²⁺ concentrations can induce ferroptosis while facilitating cuproptosis [174]. Consequently, an interaction exists between cuproptosis and ferroptosis, with both working together to provide anti-cancer effects in lung cancer. Thus, harnessing their synergistic potential for anti-tumor immunotherapy presents a highly promising therapeutic approach.

Disulfidposis represents an alternative form of cellular death, mainly identified by its impact on the intracellular redox equilibrium. This imbalance results in a reduction of antioxidants like glutathione, which can lead to the improper formation of disulfide bonds. Such changes disrupt protein folding and functionality, ultimately resulting in cellular malfunctions and death [175]. You et al. discovered several prognostic genes linked to both cuproptosis and disulfidposis, including FURIN, RHOV, ARNTL2, and HLA-DQA1, by analyzing an external dataset. They further confirmed a notable increase in FURIN and RHOV expression in the A549 and H1650 cell lines through experimental methods [176]. This research contributes to identifying new biomarkers for predicting LUAD mechanisms that involve cuproptosis and disulfidposis, highlighting a potential relationship between the two. However, additional studies are needed to determine whether their interaction is synergistic or antagonistic.

Apoptosis refers to the programmed cell death mechanism, which incorporates both intrinsic (mitochondrial) and extrinsic (death receptor) pathways [177]. Research indicates a significant correlation between heightened levels of ROS and mitochondrial damage during apoptosis [178]. In their study, Li et al. demonstrated that Hydrazone copper(II) complexes promote cuproptosis by diminishing GSH levels, resulting in DLAT aggregation and a reduction in FDX1 protein expression, which in turn triggers protein toxicity stress. Additionally, these complexes elevate the expression of apoptosis-related proteins, specifically cleaved PARP and cleaved caspase 3, thus activating the apoptosis pathway. This evidence implies that Hydrazone copper(II) complexes have anti-lung cancer effects through various mechanisms, which include cuproptosis and apoptosis [179]. Further investigations revealed that a biological complex comprised of Cu²⁺-coordinated lignosulfonate (CLS)/doxorubicin (DOX) biological complex (LCD) releases both DOX and Cu²⁺ in the context of high GSH and low pH within lung cancer cells, triggering copper-mediated cell death. This occurs through the reduction of the mitochondrial membrane potential and the downregulation of FDK1 and DLAT protein expressions. The experiment also showed an increase in Bax and cleaved caspase 3 levels, alongside a decrease in Bcl-2, thereby confirming that ROS promotes apoptosis via Fenton reactions involving Cu²⁺ [180]. Another investigation showed that a copper-based metal-organic framework (Cu-MOF) liberates copper ions in NSCLC, which not only enhances Fenton reactions to produce excessive hydroxyl radicals—leading to oxidative damage and hastening caspase-3 activation—but also binds with DLAT, resulting in the loss of Fe-S cluster proteins and the accumulation of acylated proteins, ultimately causing protein toxicity stress-induced cuproptosis [181]. Consequently, a synergistic interaction between apoptosis and cuproptosis exists, and their combined application can effectively hinder the proliferation of lung cancer cells.

The anti-cuproptosis mechanism in lung cancer

Regulate proteins related to copper metabolism

Lung cancer cells may bolster their capacity to expel copper ions through the upregulation of copper transport proteins ATP7A and ATP7B, alongside an increase in ATOX1 levels and a reduction in the expression of CTR1 and Divalent Metal Transporter 1 (DMT1). This process diminishes intracellular copper ion levels, thereby preventing them from reaching a threshold that could trigger copper-induced apoptosis, thus avoiding cell death. Research has indicated that elevated expression of ATP7A and ATP7B is linked to the emergence of resistance against platinum-based chemotherapy agents in ovarian cancer cells [182]. Investigations conducted by Zhu et al. have revealed that the levels of ATP7A in diverse tumor cell lines are associated with heightened resistance to cisplatin. Additional experiments validated that tumor populations lacking ATP7A displayed greater sensitivity to cisplatin chemotherapy than those with typical ATP7A expression [183]. Consequently, a similar mechanism could be implicated in lung cancer, although further investigation is required to verify this hypothesis. ATOX1 interacts with Cu⁺, thereby aiding in its export. Studies by Jin et al. demonstrate that the deletion and inhibition of ATOX1 increase the sensitivity of tumor cells to gemcitabine, while heightened ATOX1 levels contribute to resistance against genotoxic agents [184]. Reducing ATOX1 expression facilitates the buildup of cisplatin and copper within cells, thereby augmenting the therapeutic impact of cisplatin [185]. Research indicates that heightened expression of CTR1 leads to increased levels of intracellular copper and makes cells more vulnerable to both copper-induced toxicity and radiotherapy. Intriguingly, when CTR1 is absent, copper levels remain unchanged, and sensitivity to copper-induced toxicity and radiotherapy is not impacted. Additional investigations conducted by Lei et al. established that DMT1 might offset the absence of CTR1 by enhancing copper transport, with DMT1 levels indeed showing an upregulation following CTR1 loss. Significantly, it is only when both CTR1 and DMT1 are simultaneously deficient that there is a notable decrease in copper accumulation, as well as diminished copper-induced toxicity and sensitivity to radiotherapy [186].

Strengthen the antioxidant defense system

Excessive copper can lead to a notable increase in the production of ROS [187]. Consequently, lung cancer cells may boost their capacity to detoxify ROS by enhancing the expression of antioxidant enzymes like SOD and GPX. This response helps alleviate oxidative harm induced by ROS and provides resistance against cell death triggered by copper. Research conducted by Miyake and colleagues revealed that the overexpression of SOD1 plays a crucial role in developing resistance to alectinib within ALK-positive lung adenocarcinoma cell lines. To suppress SOD1 expression, they utilized siSOD1, and the outcomes demonstrated that the combination of siSOD1 and alectinib exhibited superior effectiveness compared to using alectinib alone [188]. In a related study, it was observed that chemoresistant A549 cells showed a significant upregulation of GPX2 protein levels and the drug resistance marker multidrug resistance protein 1 (MPP1) when compared to A549 cells, while ROS levels were markedly lower. This suggests that elevated GPX2 expression contributes to reduced ROS levels in lung cancer, thereby promoting chemoresistance [189].

Regulate cellular metabolic pathways

Cuproptosis plays a crucial role in mitochondrial function, leading lung cancer cells to modify their energy metabolic pathways in order to decrease reliance on mitochondrial oxidative respiration, thus minimizing the probability of copper-dependent cell death. Cancer cells enhance glucose absorption to generate lactate, a phenomenon commonly referred to as the Warburg effect. The buildup of lactate subsequently alters the immune microenvironment and facilitates the cancer cells’ ability to evade immune detection [190, 191]. A study by Li et al. revealed that circumRUNX1 is upregulated in NSCLC and promotes both glycolysis and lactate production via the miR-145/HK2 pathway, aiding in tumor cell immune evasion [192]. Furthermore, high levels of circRUNX1 expression have been correlated with unfavorable outcomes in lung adenocarcinoma, increased tumor size, and resistance to anti-PD-1 immunotherapy [193]. CircRUNX1 also accelerates lung adenocarcinoma cell proliferation and metastasis by targeting the miR-5195-3p/HMGB3 pathway [194]. Consequently, lung cancer cells are able to sustain their energy requirements through enhanced glycolytic pathways, ensuring a constant energy supply even when copper levels interfere with mitochondrial functionality, which is essential for cell survival. The mitochondrial uncoupling protein 2 (UCP2) is significantly elevated in lung cancer, contributing to tumor development, progression, and chemotherapy resistance [195]. UCP2 not only facilitates a metabolic transition towards glycolysis that supports cancer advancement but also diminishes oxidative stress and ROS production by modulating energy metabolism [196, 197]. Copper functions as a vital regulatory factor for the autophagic kinases ULK1 and ULK2. Increased intracellular copper concentrations can boost the function of ULK1 and ULK2 kinases, thereby enhancing autophagic flux and fostering the growth and survival of lung tumor cells. However, in mouse models of KRASG12D-driven lung cancer, the lack of CTR1 has been shown to diminish both autophagy and cellular proliferation [129].

Activate the cellular stress response and repair mechanism

Heat shock proteins (HSPs) are essential for cellular responses to stress and are found to be overexpressed in various types of tumors, playing significant roles in tumorigenesis, progression, and resistance to treatment [198]. DNAJC24 belongs to the HSP family, and a study conducted by Liu et al. identified a high expression level of DNAJC24 in tissue samples from LUAD. They also established that increased expression of DNAJC24 facilitates the proliferation and invasion of LUAD cells [199]. This indicates that lung cancer cells might improve their survival mechanisms by activating HSP family members’ protein expression, which assists in managing copper-induced protein damage and stress responses, thus stabilizing the structure and function of intracellular proteins. Additionally, research by Choi et al. utilized both in vivo and in vitro methods, demonstrating that the combination of NK16 (an HSP27 inhibitor) with either cisplatin or paclitaxel is more effective in inhibiting tumor growth than using cisplatin or paclitaxel alone, which is linked to HSP27’s role in enhancing sensitizing activities [200].

Copper overload can lead to DNA damage, prompting lung cancer cells to upregulate DNA repair-related gene expression. This upregulation enhances their ability to repair DNA and minimizes cell death due to DNA damage, thereby mitigating the effects of copper-induced cytotoxicity. Recent research has pinpointed ALDH7A1 as a novel driver gene influencing DNA methylation, revealing notably high expression levels in lung squamous cell carcinoma (LUSC) cell lines and clinical specimens, with a negative correlation observed with methylation status. In vitro investigations demonstrated that silencing ALDH7A1 reduced the proliferation of lung cancer cells, while increased expression of this gene facilitated cellular progression [201]. EIPR1, also referred to as tumor suppressor subchromosomal candidate gene 1 (TSSC1), is an oncogene that is overexpressed in lung cancer, playing a significant role in DNA damage and repair processes [202]. A study conducted by Zheng et al. established that EIPR1 is overexpressed in LUAD, and the silencing of EIPR1 resulted in the inhibition of growth, invasion, and migration in LUAD cells [203].

Impact of genetic variations in copper metabolism on programmed cell death-based therapeutic strategies

Variations in genetic factors related to copper metabolism regulation significantly affect the response to tumor therapies. Large-scale sequencing studies in clinical settings have demonstrated that the A > C polymorphism located at the CTR1 rs10981694 site notably heightens the risk of cisplatin-induced ototoxicity in patients with NSCLC, with individuals carrying the C allele presenting with dose-limiting toxicity traits [204]. Importantly, structural alterations in the copper transporter CTR1 can disrupt transmembrane transport, leading to cross-resistance in tumor cells against platinum-based chemotherapy agents [205]. In the context of hereditary disorders related to copper metabolism, mutations in the ATP7A and ATP7B genes result in Menkes disease and Wilson’s disease, respectively, both of which are marked by impaired transmembrane transport of copper ions, potentially resulting in copper accumulation across various organs [60, 206]. Research into the mechanisms reveals that the accumulation of copper in lysosomes, due to the inactivation of ATP7B, can modify patterns of cell death through the activation of the autophagy pathway mediated by TFEB [71]. Genetic variations in FDX1, a key regulator of copper-induced cell death, demonstrate considerable clinical diversity. Loss-of-function mutations in this gene can obstruct the acylation process of the DLAT protein, leading to the silencing of the copper death signaling pathway. Moreover, lung cancer patients with reduced FDX1 expression show significantly less sensitivity to treatments involving copper ion carriers [146, 181, 207]. Notably, the copper metabolism regulatory network has a close interplay with the ferroptosis pathway: COMMD10 promotes sensitivity to ferroptosis by chelating intracellular copper ions, while disruptions in copper homeostasis can hinder the ferroptosis process through the HIF1α-CP/SLC7A11 signaling pathway [208]. These discoveries indicate that variations in genes associated with copper metabolism play a crucial role in selectively activating programmed cell death pathways through various mechanisms.

Potential drugs targeting cuproptosis therapy for lung cancer

Among the copper ion carrier drugs, elesclomol [209]and disulfiram [210] have received the most attention. They can cause cell death by transferring copper ions into cells and mitochondria, which also leads to DLAT oligomerization, reduced Fe-S stability, and interactions with NPL4 [211]. Elesclomol, an anticancer drug that targets mitochondrial metabolism, has been found in modern research to inhibit cancer by inducing cuproptosis through modulation of extracellular copper ion transport [212]. UCP2 plays a role in tumor aggressiveness and anticancer drug resistance by attenuating ROS production. A study showed that high expression of UCP2 may limit the antitumor effects of elesclomol by attenuating the ROS response, whereas treatment of A549 lung cancer cells with elesclomol and genipin blocked the UCP2 pathway to reduce glucose uptake and increase the production of intracellular and mitochondrial ROS, which induced cell death and thus inhibited tumor growth, which may be related to the induction of cellular cuproptosis, but this needs to be verified by further experiments [213]. In addition, elesclomol increased ROS levels to selectively kill cisplatin-resistant lung cancer cells [214]. The most recent study found that in vivo and vitro experiments Osimertinib (Osi) combined with elesclomol significantly down-regulated the expression of iron-sulfur cluster (ISC) protein and mitochondrial acyltransferase protein in lung cancer cells in both in vivo and ex vivo experiments, which induced cuproptosis and inhibited the growth of tumors. In addition, the combined treatment of the two also effectively inhibited oxidative phosphorylation (OXPHOS) activity in adaptive-resistant cells [215]. Liu et al. [216] found that FDX1 was significantly downregulated in LUAD tissues and was associated with lower survival cycles. The proliferation, migration and invasion of LUAD cells were impaired by high expression of FDX1 leading to a GPRIN2 expression-dependent increase, which induced cuproptosis. Li et al. [146] found that disulfiram upregulated ATP7B and PD-L1 expression in A549 cells and inhibited cell viability. Further experiments demonstrated that the combination of disulfiram and JQ-1 (a PD-L1 inhibitor) increased ROS and malondialdehyde (MDA), decreased superoxide dismutase (SOD) to promote oxidative stress, and upregulated solute carrier family 31 member 1 (SLC31A1) and FDX1 expression, inhibiting ATPase copper-transporting β (ATP7B), succinate dehydrogenase B (SDHB), programmed death-ligand 1 (PD-L1), and hypoxiainducible factor-1 A (HIF-1 A) expression to induce cuproptosis.

It was recently discovered that copper(II) bis(diethyldithiocarbamate) (CuET), a strong anticancer agent, is a physiologically active metabolite of the medication disulfiram, which is used to misuse alcohol [217]. Through experimentation, it was discovered that CuET and CuET nanoparticles (NPs) had strong resistance to GSH reduction and cytotoxicity, which resulted in both cellular DNA damage and NPL4 immobilization. Further research revealed that they could also up-regulate the expression of FDX1, which results in cellular cuproptosis. This suggests that CuET and CuET NPs target NPL4 and cuproptosis to prevent the proliferation of A549/DDP cells [218].

There is a syphilis mimetic TP0751-peptide decorated stem cell membrane-coated copper-based metal organic framework (Cu-MOF) nanodelivery platform for the targeted delivery of siATP7a in vivo, while SiATP7a was loaded in a syphilis mimetic TP0751-peptide decorated stem cell membrane-coated copper-based metal organic framework to obtain TP-M − Cu − MOF/siATP7a nanoparticles. Research has demonstrated that TP-M-Cu − MOF/siATP7a can block copper transporters by up-regulating FDX1 and down-regulating COX1, COX17, and SOD. This leads to intracellular copper buildup, which in turn causes cuproptosis and prevents brain metastasis of SCLC [219].

Copper chelators are compounds that can form chelates with copper ions, and common copper chelators include D-penicillamine (DPEN) [220], ammonium tetrathiomolybdate (ATTM) [221], and triethylenetetramine (TETA) [222], etc. ATTM, a potent copper chelator, has been widely utilized for the treatment of Wilson’s disease in the clinic. According to Li et al. [223], PRPF6 m⁶ A methylation, which is reliant on YTHDF1, is facilitated by low levels of ATTM and leads to the proliferation, migration, and invasion of lung adenocarcinoma cells. H₂S was also shown to be an effector in this process, and it is interesting that eliminating H₂S might mitigate the adverse effects of ATTM in the treatment of lung cancer. Tetrathiomolybate (TM) also caused cisplatin-resistant lung cancer cells to produce more ROS and less GSH, which increased Pt DNA adducts and caused death [224]. DPEN is a copper chelating agent and amino mercaptan that is used to treat rheumatoid arthritis, cystinuria, and Wilson’s disease. Research has demonstrated that the co-administration of DPEN and CuSO₄ led to an elevation in H₂O₂ content inside cancer cells and a reduction in lung cancer cell viability. Tumor development was inhibited by the enhancement of H₂O₂ induced cell death when 250 µM Fe sucrose was added. These findings imply that DPEN induced H₂O₂ mediated cell death is mostly dependent on redox-active Fe and Cu [70]. To improve the effectiveness and possible use of tetravalent platinum in NSCLC, Fang et al. created nanoscale tetravalent platinum (HSA@Pt) that is responsive to GSH and based on albumin. By combining it with TM in experiments, they increased the concentrations of platinum and copper in lung cancer cells by decreasing the expression levels of ATP7B and PD-L1, which led to cellular stress and produced an antitumor effect [225]. Therefore, disrupting copper homeostasis as well as inducing cuproptosis induces lung cancer cell death and inhibits its proliferation, migration and invasion, which is a very promising therapeutic approach (Table 3).

Table 3.

Potential drugs for treating lung cancer visa Cuproptosis

Drugs	Research subject	Dose	Effects/mechanisms	Cuproptosis biomarkers	Ref
Elesclomol and Genipin	A549 human lung cancer cells	20 mM; 250 mM	Blocking the UCP2 pathway, reducing glucose uptake, and increasing ROS production in cells and mitochondria.	UCP2↓	[213]
Elesclomol	SCLC1, SCLCSR2, SCLCB, SCLCBC, NSCLCS, and NSCLCSC cell lines	10 mM	Increasing ROS production.	-	[214]
Osi and Elesclomol	NSCLC cell lines and BALB/c nude mice	0.1 nM (in vitro); 5 mg/kg (in vivo)	Downregulate the expression of ISC protein and mitochondrial acyltransferase protein, suppressing OXPHOS activity.	-	[215]
CuET and CuET nanoparticles	A549 cells, A549/DDP cells, and athymic nude mice	500 nM; 917 nM	Immobilizing NPL4, damaging DNA, and up-regulated FDX1 expression to induce cuproptosis.	FDX1↑	[218]
The FDX1 overexpression plasmid	A549 cells, H1975 cells, and BALB/c nude mice	Constructed using the pLVX-puro lentiviral vector and targeting FDX1 was generated	A GPRIN2-dependent increase induces cuproptosis, impairing the proliferation, migration, and invasion ability of LUAD cells.	-	[216]
Disulfiram and JQ-1(a PD-L1 inhibitor)	A549 cells	1 µL and 5 µL	Raise ROS and MDA, reduce SOD to promote oxidative stress, and upregulate SLC31A1 and FDX1, while inhibiting ATP7B, SDHB, PDL-1, and HIF-1 A to induce cuproptosis.	SLC31A1↑、FDX1↑、ATP7B↓、SDHB↓	[146]
TP-M − Cu − MOF/siATP7a	H69, HBE, and bEnd.3 cells	200 nM siATP7a (in vitro); 1 mg siATP7a equiv./kg (in vivo)	Upregulation of FDX1, downregulation of COX1, COX17, and SOD to inhibit copper transporters, leading to intracellular copper accumulation and inducing cuproptosis	FDX1↑、COX1↓、COX17↓、SOD↓	[219]
ATTM	A549, HCC827, and PC9 cells	60 µM	Low ATTM levels promote lung adenocarcinoma cell growth, migration, and invasion through YTHDF1-dependent PRPF6 m6A methylation. H2S was involved in the above effects of ATTM	-	[223]
TM	H1299 cells, A549 cells, and athymic NCR nu/nu-nude mice	TM/DDP combination at a constant ratio	The decrease of GSH, and the increase of ROS and Pt DNA adducts, thus inducing apoptosis.	-	[224]
DPEN	MB231 cells, H1299 cells, H292 cells, and athymic nude mice	100 µM (in vitro); 150 mg/kg (in vivo)	Increase H2O2 concentration in lung cancer cells and induce cell death	-	[147]
TM + HSA@Pt	A549 细胞	HSA@Pt: 10 µM Pt and TM: 100 µM	Inhibit the expression of copper transporter proteins ATP7B and PD-L1, and block the excretion of platinum and copper	ATP7B↓、PD-L1↓	[225]

Discussion

Copper serves as a vital trace element within organisms, making it crucial to maintain copper homeostasis for the proper functioning of biological processes. Recently, cuproptosis has emerged as a distinct mode of cell death, separate from apoptosis, necrosis, autophagy, and ferroptosis. Its unique mechanism of action is essential in cancer treatment. In China, the incidence and mortality rates of lung cancer are alarmingly high, posing a significant threat to public health. This situation underscores the urgent need to explore novel therapeutic approaches for lung cancer, as current treatments often fall short of effectiveness. The identification of cuproptosis has paved the way for innovative strategies in lung cancer therapy; however, research into the relationship between lung cancer pathogenesis and cuproptosis remains limited. Cuproptosis is characterized by a complex set of processes, and the underlying molecular mechanisms are not yet fully understood. Gaining deeper insights into the signaling pathways and regulatory aspects of copper-induced cell death is critical for the advancement of new anti-lung cancer therapies.

In this study, we examined the concept of copper homeostasis, the processes involved in cuproptosis, and the connection between cuproptosis and lung cancer. Additionally, we investigated the involvement of genes and proteins associated with cuproptosis in lung cancer. Our results indicated a significant correlation between copper levels and the progression of lung cancer in patients, suggesting a partial link between cuproptosis and lung cancer, with evidence that cuproptosis is inhibited in lung cancer patients due to disruptions in their copper ion balance. Consequently, inducing cuproptosis in lung cancer cells emerges as a highly promising therapeutic strategy. We offer a summary of the mechanisms that identify proteins related to copper homeostasis and genes involved in cuproptosis in the context of lung cancer. These can be influenced by modulating proteins such as CTR1, ATOX1, FDX1, CCS, COX17, ATP7A, and ATP7B, alongside LIPT1, various LncRNAs (including AL691432.2, AC093010.2, AC107464.3, COLCA1, AC026471.3, LINC01833, and ITGB1-DT), as well as genes like DβH, LOXL2, SOD1, UBE2D1, and UBE2D3 for assessing clinical treatments for lung cancer patients, predicting risk, and identifying drug resistance. We discovered that copper ion carrier medications (such as elesclomol and disulfiram), copper chelators (including DPEN, ATTM, and TETA), and nanoparticles designed for copper transport can effectively modulate copper ion levels in lung cancer cells, thus triggering cuproptosis as a potential lung cancer treatment. Moreover, our research indicates that lung cancer cells might overcome the detrimental impacts of cuproptosis via various compensatory survival strategies. These strategies encompass the modulation of proteins associated with copper metabolism (such as ATP7A, ATP7B, ATOX1, CTR1, and DMT1), bolstering the antioxidant defense system (including SOD and GPX), modifying metabolic pathways (specifically the glycolytic pathway), and initiating cellular stress responses and repair processes (such as HSP activation and the upregulation of genes related to DNA repair). Consequently, it is crucial to take these mechanisms into account in future basic and clinical studies to assess whether cuproptosis inducers can successfully impede the compensatory copper metabolism mechanisms in lung cancer cells, with the goal of achieving enhanced anti-cancer efficacy. Additionally, upcoming research could focus on establishing lung cancer cell models that are subjected to prolonged exposure to cuproptosis inducers, in order to investigate how cells progressively gain resistance and if the compensatory survival strategies evolve throughout the resistance development. This approach will provide valuable insights into the potential resistance pathways in lung cancer cells, laying the foundation for future modifications in treatment approaches.

Currently, the exploration of the cuproptosis mechanism remains largely undeveloped, and several critical factors must be addressed. To begin with, there is a paucity of experiments investigating the cuproptosis mechanism. The pathways for intervention are relatively narrow, and the explanation of this mechanism lacks depth, highlighting the need for more researchers to engage and conduct thorough studies at a more advanced level across various pathways, thereby examining the connections between different phases of cuproptosis and lung cancer. Moreover, much of the cuproptosis research tends to be centered around fundamental experiments involving cells and animals, with insufficient clinical trials assessing patients alongside cuproptosis-related proteins and genes. This limitation diminishes its clinical significance, and the practical application of cuproptosis faces numerous hurdles ahead. Finally, it is essential to recognize that the induction of cuproptosis in lung cancer cells is influenced by various factors, including dosage, cell type, individual variability, and interactions with other medications. Additional experimental investigations are crucial to enhance the specificity and targeting of cuproptosis modulation in lung cancer cells, evaluate safety and toxicity, and meet therapeutic objectives while minimizing adverse effects. When inducing cuproptosis in lung cancer cells, it is vital to prevent carcinogenic inflammation while promoting effective anti-cancer immune responses. The conversion of research findings into practical applications for lung cancer encounters various obstacles. A significant challenge is the absence of a unified molecular typing system; at present, there are no distinctive biomarkers that can be utilized for diagnostic monitoring, efficacy assessment, and prognostic decisions. Additionally, current regulators of copper homeostasis (including carriers and chelators of copper ions) demonstrate antitumor properties, yet their unintended side effects causing cytotoxicity considerably hinder their clinical use. There is a pressing necessity to create delivery systems that are specific to tumors and to define safe dosage levels. Moreover, the adaptive evolution of tumor cells towards a singular method of cell death may result in resistance to treatment, which underscores the requirement for comprehensive investigations into the combined effects of copper-induced cell death and immunogenic cell death processes. Tackling these pivotal scientific challenges depends on the validation provided by extensive multicenter randomized controlled trials, with a particular emphasis on developing a translational medical research framework that integrates molecular typing, precise drug delivery, and combination therapy approaches.

In conclusion, the targeted manipulation of cuproptosis represents an emerging avenue for lung cancer treatment, indicating significant potential. Although advancements have been made in understanding the relationship between cuproptosis and lung cancer, the investigation into the fundamental mechanisms remains nascent. It is essential to further examine copper homeostasis and the possible molecular pathways of cuproptosis related to lung cancer. Consequently, it is anticipated that future clinical and fundamental research will delve deeper into the association between cuproptosis and lung cancer, thereby enhancing its clinical relevance within the realms of respiratory medicine and oncology. This exploration could prove vital for developing effective treatment strategies and pioneering new pharmaceutical interventions.

In summary, the strategic manipulation of cuproptosis has emerged as a hopeful new direction for lung cancer treatment. While advancements have been made in comprehending the fundamental mechanisms of cuproptosis and lung cancer, further investigation is necessary to thoroughly grasp the intricacies of copper homeostasis and the potential molecular pathways linking cuproptosis to lung cancer. To better elucidate the connection between lung cancer and cuproptosis, additional basic and clinical studies are expected in the future. This will enhance the clinical relevance in the domains of oncology and respiratory health, which could lead to meaningful consequences for the development of innovative therapies and effective treatment strategies.

Conclusion

Cuproptosis represents a new copper-dependent mechanism of cellular death, showcasing significant promise for lung cancer therapy. The primary process involves an overload of copper ions, resulting in the abnormal oligomerization of mitochondrial acylated proteins (including DLAT) and the destabilization of Fe-S cluster proteins. This sequence leads to proteotoxic stress and a collapse of energy metabolism. Additionally, the irregular expression of critical regulatory genes (including FDX1 and LIPT1) and transport proteins (such as CTR1 and ATP7A/B) is strongly linked to lung cancer progression. Therapeutic approaches should prioritize copper ion carriers (like Elesclomol and disulfiram) as well as targeted delivery systems (such as nanoparticles). When combined with immune checkpoint inhibitors, these strategies can work together to effectively induce cuproptosis and potentially overcome treatment resistance. Such findings open up new avenues for lung cancer therapy, with the possibility of enhancing patient outcomes. Future investigations ought to explore the synergistic interactions of cuproptosis with other cell death mechanisms and to create personalized biomarkers aimed at optimizing treatment protocols for targeted lung cancer care.

Author contributions

Cheng Luo: Conceptualization, Formal analysis, Writing - original draft, Writing - review & editing. Xinhui Wu: Writing - original draft, Software. Shipeng Zhang: Writing - original draft. Junwen Tan: Formal analysis. Bo Ning: Writing - original draft. Xinyue Zhang: Writing - original draft. Yuzhi Huo: Writing - original draft. Yuanhang Ye: Formal analysis, Software, Writing - original draft. Fei Wang: Conceptualization, Project administration, Supervision, Funding acquisition, Writing - review & editing.

Funding

This work was funded by Joint Innovation Fund of Health Commission of Chengdu and Chengdu University of Traditional Chinese Medicine (2024120973), National Science and Technology Major Project (2020YFC2003104) and National Natural Science Foundation of China (82174347).

Data availability

No datasets were generated or analysed during the current study.

Declarations

Ethical approval and consent to participate

Not applicable.

Consent for publication

All authors are aware and have agreed to publish.

Competing interests

The authors declare no competing interests.