Copper homeostasis imbalance and cuproptosis: Emerging targets and strategies for gastrointestinal tumor therapy

Table 1 Key cuproptosis regulators in gastrointestinal tumors

Regulator	Main role in cuproptosis	Relevance in gastrointestinal tumors	Evidence level	Ref.
SLC31A1/CTR1	Mediates copper influx and contributes to intracellular copper accumulation	Associated with copper and platinum drug uptake; altered expression may affect therapeutic response in digestive tumors	Clinical association + preclinical evidence	[29,68]
ATP7A/ATP7B	Copper efflux transporters that reduce intracellular copper accumulation	Upregulation is associated with platinum resistance and altered copper homeostasis in GC, CRC, and esophageal cancer	Clinical association + functional studies	[66,67,69-74]
ATOX1	Copper chaperone involved in copper transport and transcriptional regulation	Supports tumor proliferation and copper-dependent signaling in gastrointestinal malignancies	Preclinical + clinical association	[29,32,34]
FDX1	Reduces Cu2+ to Cu+ and supports LIAS-dependent protein lipoylation	Frequently downregulated in GC/CRC; low expression is associated with poor prognosis and reduced cuproptosis sensitivity	Bioinformatic cohorts + mechanistic studies	[44,87-93]
LIAS	Catalyzes lipoic acid biosynthesis required for mitochondrial protein lipoylation	LIAS regulation affects cellular sensitivity to elesclomol and copper-induced cuproptosis	Preclinical mechanistic evidence	[44,121,123]
DLAT	Lipoylated TCA-cycle protein and key substrate for copper-induced aggregation	DLAT abundance may influence mitochondrial metabolism, prognosis, immune features, and response to cuproptosis induction	Preclinical + clinical association	[42,43,94,235,236]
MTF1/FTH1/ISCA2	Regulates metal stress, iron storage, and Fe-S cluster homeostasis	May suppress both ferroptosis and cuproptosis sensitivity in GC by promoting iron storage and Fe-S cluster assembly	Preclinical mechanistic evidence	[106]
HIF-1α	Promotes glycolytic reprogramming and reduces mitochondrial dependence	Hypoxia/HIF-1α activation may reduce cuproptosis sensitivity by suppressing TCA-cycle activity and FDX1/DLAT expression	Preclinical evidence	[47,76,269]
CDKN2A/SNHG26/E2F3	Resistance-associated regulators of elesclomol-induced cuproptosis	Associated with resistance to cuproptosis induction in CRC models	Preclinical evidence	[125,126,240,241]
PTBP3/COX11 axis	Alters mitochondrial copper handling	PTBP3-mediated COX11 exon skipping may reduce mitochondrial copper content and contribute to cuproptosis evasion in GC	Preclinical evidence	[243]

SLC31A1: Solute carrier family 31 member 1; CTR1: Copper transporters; ATP7A: ATPase copper transporting alpha; ATP7B: ATPase copper transporting beta; GC: Gastric cancer; CRC: Colorectal cancer; ATOX1: Antioxidant 1 copper chaperone; FDX1: Ferredoxin 1; LIAS: Lipoic acid synthase; DLAT: Dihydrolipoamide S-acetyltransferase; TCA: Tricarboxylic acid cycle; MTF1: Metal regulatory transcription factor 1; FTH1: Ferritin heavy chain 1; ISCA2: Iron-sulfur cluster assembly 2; HIF-1α: Hypoxia-inducible factor-1α; CDKN2A: Cyclin dependent kinase inhibitor 2A; SNHG26: Small nucleolar RNA host gene 26; E2F3: E2F transcription factor 3; PTBP3: Polypyrimidine tract binding protein 3; COX11: Cytochrome c oxidase assembly factor 11.

Table 2 Magnetic resonance imaging-guided copper-based theragnostic strategies

Imaging strategy	Representative platform	Main therapeutic mechanism	Evidence status/limitation	Ref.
MRI-guided copper delivery	Copper-DNA nanoparticles	Tumor imaging, Fenton-like ROS generation, mitochondrial dysfunction, ICD	Shows imaging-therapy integration, but cuproptosis specificity requires further validation	[270]
T1-weighted MRI + PTT/CDT	CuS/Mn2+ hybrid nanogels	MRI-guided photothermal and chemodynamic therapy	Strong imaging signal and synergistic therapy; mainly preclinical	[271]
T1-weighted MRI + PTT	Ultrasmall Cu1.2O nanoparticles	MRI-guided photothermal ablation	Demonstrates copper-based imaging potential; direct cuproptosis markers are limited	[272]
MRI-guided multi-metal therapy	Fe3O4@C/CuOx nanoenzymes	MRI guidance, chemotherapy, PTT, copper/iron-mediated cytotoxicity	Multifunctional but mechanistically complex	[273]
TME-responsive MRI	Cu-Fe peroxide-containing nanoparticles	Cu-assisted iron cycling and Fenton amplification	Strong redox rationale; biosafety and clearance need validation	[274]
MRI-guided PDAC therapy	Collagenase-modified copper-containing hollow mesoporous silica nanoparticles	Stromal modulation and copper-induced cytotoxicity	Tumor-specific design for PDAC; translation remains early	[255]
MRI-guided ferroptosis/cuproptosis/CDT	CuO2-loaded dendritic macromolecule/metal-polysaccharide nanocomposites	TME regulation, ROS amplification, ferroptosis and cuproptosis	Promising combination design, but pathway attribution remains challenging	[275]
MRI + NIR-triggered cascade therapy	Cu/Mn-doped iron oxide nanocrystals	Drug release, Cu2+ chelation, ferroptosis/cuproptosis cascade	Integrates imaging and cascade therapy; preclinical validation needed	[276]
Activatable MRI + PDT/CDT	GSH/H2O2-responsive magnetic Cu2+ nanocomplex	“On-off” MRI activation, Cu+ release, hydroxyl radical generation, PDT enhancement	Smart activation design; in vivo specificity requires further testing	[277]
MRI-guided chemo-immunotherapy	Phosphorus dendrimer-copper complexes	Mitochondrial dysfunction, ER stress, immunotherapy enhancement	Illustrates theragnostic potential, but not exclusively cuproptosis-driven	[278]

MRI: Magnetic resonance imaging; ROS: Reactive oxygen species; ICD: Immunogenic cell death; PTT: Photothermal therapy; CDT: Chemodynamic therapy; PDAC: Pancreatic ductal adenocarcinoma; TME: Tumor microenvironment; NIR: Near-infrared; GSH: Glutathione; ER: Endoplasmic reticulum.

Table 3 Positron emission tomography and multimodal imaging strategies for copper-based theragnostics

Imaging strategy	Representative platform	Main therapeutic mechanism	Evidence status/limitation	Ref.
64Cu-PET + phototherapy	64Cu-labeled porphyrin-lipid nanoparticles	PET tracking of tumor uptake and photochemical ablation	Useful for biodistribution monitoring; cuproptosis relevance is indirect
64Cu-PET + chemotherapy	CCR2-targeted Cu@CuOx nanoparticles loaded with gemcitabine	PET imaging and drug delivery in PDAC	Tumor-targeted strategy; clinical validation required	[279]
64Cu-PET + chemo/radiotherapy	Albumin-binding camptothecin nanoprodrug	Tumor retention, PET imaging, chemotherapy and radiotherapy	Strong theragnostic design; mainly proof-of-concept	[280]
64Cu-PET targeted therapy	64Cu-labeled immunoliposomes	EGFR-targeted PET imaging and therapy	Applicable to receptor-high tumors; tumor selectivity is key	[281]
PET-guided BNCT	64Cu-chelated boron neutron capture therapy platform	PET tracking of boron agent accumulation	Supports treatment planning; not primarily cuproptosis-based	[282]
UCL/CT/MRI-guided therapy	Upconversion nanoplatforms encapsulating CuS	Radiotherapy and PTT	Multimodal imaging enables guidance, but platform complexity is high	[283]
Four-modal imaging	CuS and rare-earth nanoparticle-loaded zeolitic imidazolate composites	Imaging-guided chemoradiotherapy	Broad imaging capacity; translational reproducibility uncertain
MRI-guided X-ray PDT	Copper-cysteine nanoparticles	Deep-tumor PDT under X-ray irradiation	Suitable for deep lesions; mechanism is mainly ROS-based	[284]
Fluorescence/MRI-guided CDT	CuS/Gd2O3based nanoprobes	Thermally enhanced CDT	Useful dual-modal design; cuproptosis specificity remains to be proven	[285]
Multiparametric MRI response monitoring	CuS@GOD nanoparticles	Starvation therapy, ROS generation, treatment response assessment	Imaging mainly monitors response rather than directly proving cuproptosis	[286]

PET: Positron emission tomography; CCR2: C-C motif chemokine receptor 2; PDAC: Pancreatic ductal adenocarcinoma; EGFR: Epidermal growth factor receptor; BNCT: Boron neutron capture therapy; UCL: University College London; CT: Computed tomography; MRI: Magnetic resonance imaging; PTT: Photothermal therapy; PDT: Photodynamic therapy; ROS: Reactive oxygen species; CDT: Chemodynamic therapy.

Table 4 Therapeutic strategies targeting cuproptosis and their evidence level

Strategy	Representative mechanism	Current evidence level	Main limitation	Ref.
Copper ionophores	Increase intracellular copper and induce mitochondrial copper toxicity	Mainly preclinical tumor models	Systemic toxicity, delivery instability, and patient selection remain unresolved	[119,120,122-127]
Disulfiram/CuET-based therapy	Forms cytotoxic copper complexes and induces oxidative/mitochondrial stress	Preclinical and organoid evidence	Stability, specificity, and mechanism heterogeneity	[128-134]
FDX1-LIAS-DLAT axis modulation	Enhances lipoylated substrate availability and copper sensitivity	Preclinical mechanistic evidence	Requires validated biomarkers and rescue experiments	[92-98,137-146]
Metabolic sensitization	Shifts tumor cells from glycolysis toward OXPHOS to increase cuproptosis susceptibility	Preclinical evidence	Tumor metabolic states are heterogeneous and context-dependent	[47,50,140,269]
Chemotherapy sensitization	Combines copper stress with platinum drugs, 5-FU, gemcitabine, or metabolic stress	Preclinical evidence in GC, CRC, and PDAC models	Optimal tumor subtype and treatment sequence remain unclear	[147-150]
Immunotherapy combination	Cuproptosis-associated mitochondrial stress may enhance cGAS-STING activation, ICD-like responses, and immune checkpoint blockade	Preclinical evidence	Immune activation is context-dependent and should not be considered the defining mechanism of cuproptosis	[151-160,287,288]
TME-responsive nanomedicine	pH/GSH/H2O2-triggered copper release, ROS amplification, and mitochondrial injury	Preclinical nanoplatform studies	Platform complexity, biodistribution, clearance, and reproducibility	[203-220,289-293]
PTT/PDT/CDT-enhanced cuproptosis	Uses external energy and redox cycling to enhance ROS production, copper release, and cuproptosis-related cytotoxicity	Preclinical nanomedicine evidence	Difficult to distinguish cuproptosis from CDT/PDT/PTT-induced nonspecific oxidative injury	[227,230-232]
Theranostic platforms	Imaging-guided copper delivery and response monitoring	Preclinical imaging studies	Imaging signal does not directly prove cuproptosis activation	[255,270-277,279-286,294,295]

CuET: Copper diethyldithiocarbamate; FDX1: Ferredoxin 1; LIAS: Lipoic acid synthase; DLAT: Dihydrolipoamide S-acetyltransferase; OXPHOS: Oxidative phosphorylation; GC: Gastric cancer; CRC: Colorectal cancer; PDAC: Pancreatic ductal adenocarcinoma; cGAS: Cyclic GMP-AMP synthase; STING: Stimulator of interferon genes; ICD: Immunogenic cell death; TME: Tumor microenvironment; GSH: Glutathione; ROS: Reactive oxygen species; PTT: Photothermal therapy; PDT: Photodynamic therapy; CDT: Chemodynamic therapy.

Table 5 Major resistance mechanisms and possible sensitization approaches

Resistance mechanism	Biological basis	Possible sensitization approach	Ref.
Low mitochondrial respiration/Warburg phenotype	Reduced TCA-cycle activity limits lipoylated substrate abundance and cuproptosis sensitivity	Inhibit glycolysis or shift metabolism toward OXPHOS	[46-51,75-86,269,296-306]
FDX1 downregulation	Reduces Cu2+ reduction and decreases lipoylation-related cuproptosis susceptibility	Restore FDX1 expression or block negative regulators	[87-98,143-146,307-311]
LIAS suppression	Reduces mitochondrial protein lipoylation and limits cuproptosis substrate formation	Restore LIAS expression or combine with OGT/epigenetic modulators	[121,123]
DLAT insufficiency or altered mitochondrial substrate availability	Limits aggregation of lipoylated DLAT and downstream proteotoxic stress	Increase mitochondrial TCA-cycle dependence or select DLAT-high tumors	[42,43,94,235,236]
Copper efflux activation	ATP7A/ATP7B-mediated copper export lowers intracellular copper accumulation	Inhibit copper efflux or enhance tumor copper retention	[66-74,312]
Hypoxia and HIF-1α activation	Promotes glycolysis and reduces mitochondrial respiration-dependent cuproptosis sensitivity	Combine with hypoxia modulation or metabolic reprogramming strategies	[47,245-247,269]
Dense ECM/stromal barriers	Limits penetration of copper ionophores and nanodrugs, especially in PDAC and GC	Use matrix-remodeling delivery systems or stromal-modulating strategies	[249-254,256-258]
Antioxidant buffering/high GSH	Scavenges ROS and weakens copper-dependent oxidative stress	Use GSH-depleting or redox-active nanoplatforms	[206-220,232,290-293,313]
Alternative death pathway dominance	Ferroptosis, apoptosis, ICD, or CDT-induced oxidative injury may coexist with cuproptosis, complicating mechanism attribution	Use pathway-specific inhibitors, copper chelation rescue, FDX1/LIAS/DLAT validation, and lipoylated protein aggregation assays	[62,106,114-118,221-232,312-316]
Systemic copper toxicity	Off-target copper accumulation may injure liver, kidney, brain, or other organs	Develop tumor-selective activation systems and evaluate long-term clearance and organ toxicity	[259-268]

TCA: Tricarboxylic acid cycle; OXPHOS: Oxidative phosphorylation; FDX1: Ferredoxin 1; LIAS: Lipoic acid synthase; OGT: O-GlcNAc transferase; DLAT: Dihydrolipoamide S-acetyltransferase; ATP7A: ATPase copper transporting alpha; ATP7B: ATPase copper transporting beta; HIF-1α: Hypoxia-inducible factor-1α; ECM: Extracellular matrix; PDAC: Pancreatic ductal adenocarcinoma; GC: Gastric cancer; GSH: Glutathione; ROS: Reactive oxygen species; ICD: Immunogenic cell death; CDT: Chemodynamic therapy.