Cuproptosis: A novel therapeutic target for overcoming cancer drug resistance

Acidity-unlocked glucose oxidase as drug vector to boost intratumor copper homeostatic imbalance-enhanced cuproptosis for metastasis inhibition and anti-tumor immunity

As one of the key tools of biocatalysis, natural enzymes have received extensive attention due to their unique activity. However, the non-selective catalysis and early leakage induced by delivery dependency of natural enzymes can cause side effects on normal tissues. Moreover, although cuproptosis is an emerging tumor-inhibiting programmed cell death, the occurrence of cuproptosis leads to high expression of Cu-dependent lysyl oxidase-like 2 (LOXL2), which promotes tumor metastasis. Herein, in order to intelligently regulate the "OFF-to-ON" catalytic activity of glucose oxidase (a natural enzyme called GOx) and simultaneously inhibit tumor metastasis caused by Cu imbalance, an acidity-unlocked GOx system drug carrier was constructed by co-assembling Cu ions and omeprazole (OPZ) on GOx exposing sulfhydryl and hydrophobic pockets. The GOx activity is significantly inhibited due to the coordination of Cu ions with sulfhydryl groups and the interaction of hydrophobic small molecule OPZ with hydrophobic bags, which results in specificity for tumor cells and ensures the safety of GOx in blood circulation. Meanwhile, dysregulation of intracellular Cu homeostasis that impairs the Cu-dependence of LOXL2 not only inhibits critical signaling during epithelial-mesenchymal transformation (EMT) and extracellular matrix (ECM) remodelling to prevent tumor metastasis, but also exacerbates enhanced cuproptosis induced by tumor metabolic stress, thereby reversing the immunosuppressive microenvironment. This strategy of acidity-unlocked the catalytic function of natural enzymes and LOXL2 activity inhibition provides a novel option for enhancing cuproptosis to inhibit tumor metastasis and anti-tumor immunity.

Integrating cuproptosis and immunosenescence: A novel therapeutic strategy in cancer treatment

Recent advancements in our understanding of cell death mechanisms have progressed beyond traditional apoptosis to encompass various forms of regulated cell death, notably cuproptosis. This copper-dependent cell death occurs when copper interacts with lipoylated enzymes in the tricarboxylic acid cycle, leading to protein aggregation and subsequent cell death. Alongside this, immunosenescence the gradual decline in immune function due to aging has emerged as a significant factor in cancer progression and response to treatment. Innovative strategies that integrate cuproptosis and immunosenescence are showing considerable promise in cancer therapy. By leveraging the altered copper metabolism in cancer cells, cuproptosis can selectively induce cell death, effectively targeting and eliminating tumors. Simultaneously, addressing immunosenescence can rejuvenate the aging immune system, enhancing its capacity to identify and destroy cancer cells. This dual approach creates a synergistic effect, optimizing therapeutic efficacy by directly attacking tumor cells while revitalizing the immune response. Such integration bolsters the defense against cancer progression and recurrence and holds great potential for advancing cancer treatment modalities and improving patient outcomes. This paper delves into the interactions between cuproptosis and immunosenescence, emphasizing their implications for developing innovative cancer therapies.

Cuproptosis: the mechanisms of copper-induced cell death and its implication in colorectal cancer

Colorectal cancer (CRC) represents a prevalent neoplastic disorder of the digestive tract, characterized by elevated incidence and mortality rates. The cellular metabolism of copper within CRC cells is frequently dysregulated, indicating that modifications to copper concentrations may induce cell death and potentially enhance the overall suppression of tumor progression. Cuproptosis, a recently identified form of cellular death, occurs when copper ions bind directly to the lipoylated components of the citric acid cycle (CAC) within mitochondrial respiration, thereby disrupting the balance of iron-sulfur cluster (Fe-S cluster) proteins and ultimately leading to protein toxic stress. The defining traits of cuproptosis include dependence on Cu2+ concentrations and pronounced expression in cells engaged in mitochondrial respiration. This novel mechanism has attracted significant interest within the cancer research community due to its substantial therapeutic potential in oncology. Treatments based on copper demonstrate an inhibitory effect on tumor proliferation and may facilitate approaches for treating tumors that are resistant to conventional chemotherapy. This article aims to review the significance of cuproptosis in CRC, positing that it may serve as a promising strategy for antitumor therapy and an innovative treatment paradigm to address drug resistance in cancer.

Novel Pt@PCN-Cu-induced cuproptosis amplifies αPD-L1 immunotherapy in pancreatic ductal adenocarcinoma through mitochondrial HK2-mediated PD-L1 upregulation

BACKGROUND

Copper accumulation triggers mitochondrial-driven cell death, known as cuproptosis, offering a promising mechanism for targeted cancer therapy. Recent studies have highlighted the critical role of intratumoral copper levels in regulating the expression of programmed cell death ligand-1 (PD-L1), suggesting that copper-induced cuproptosis not only enhances cancer cell death but may also amplify the effects of anti-PD-L1 antibodies (αPD-L1). However, in tumors where monotherapy with αPD-L1 shows limited efficacy, particularly in pancreatic ductal adenocarcinoma (PDAC), the role of copper-induced cuproptosis in enhancing αPD-L1 treatment efficacy and its underlying mechanisms remain unclear. Meanwhile, inadequate tumor drug accumulation and glycolysis significantly restrict the efficacy of cuproptosis. To address these challenges, we have synthesized a novel nanozyme, Pt@PCN-Cu, designed to stabilize intracellular copper accumulation and effectively induce cuproptosis. Additionally, we aim to determine whether this strong induction of cuproptosis can synergize with αPD-L1 to enhance cancer therapy, ultimately paving the way for novel strategies to improve PDAC treatment.

METHODS

Pt@PCN-Cu was synthesized via a one-pot method, and its therapeutic potential was assessed in combination with αPD-L1 for the treatment of PDAC. Initially, the material's properties were characterized, and its efficient cellular uptake was confirmed. Anti-tumor efficacy was evaluated by inducing cuproptosis in PDAC cell lines and xenograft models. RNA sequencing (RNA-seq) was utilized to identify key regulators involved in the modulation of PD-L1 expression by cuproptosis. Lastly, the therapeutic efficacy of Pt@PCN-Cu combined with αPD-L1 was evaluated in vivo, focusing on tumor growth inhibition and immune modulation within the tumor microenvironment (TME).

RESULTS

Pt@PCN-Cu demonstrates excellent physicochemical properties and remarkable cascade catalytic activity, providing a solid foundation for further in vitro and in vivo studies. In vitro, Pt@PCN-Cu efficiently transports copper and induces cuproptosis primarily through mitochondrial dysfunction. Mechanistic studies show that Pt@PCN-Cu triggers the dissociation of hexokinase 2 (HK2) from mitochondria, leading to a reduction in HK2 activity. This decline in HK2 activity impairs glycolysis, a metabolic pathway essential for tumor energy metabolism, which in turn results in elevated PD-L1 levels. In vivo, Pt@PCN-Cu demonstrates excellent safety and accumulates at the tumor site in a subcutaneous PDAC mouse model, inducing cuproptosis. Moreover, the combination of Pt@PCN-Cu with αPD-L1 further enhanced its therapeutic efficacy and effectively reprogrammed the immunosuppressive TME.

CONCLUSION

This study presents strong evidence confirming the safety and therapeutic potential of Pt@PCN-Cu in PDAC treatment. Importantly, Pt@PCN-Cu not only induces cuproptosis but also significantly enhances antitumor efficacy in combination with αPD-L1 by regulating PD-L1 expression through HK2 modulation. These findings underscore a more effective and innovative approach for treating PDAC.

Diethyldithiocarbamate-Cu4O3 nanocomplex induced mitochondrial and telomerase dysfunction in non-small cell lung cancer

BACKGROUND

Targeting cancer stem cells (CSCs)-mediated aggressive features of non-small cell lung cancer (NSCLC) is a promising anticancer approach. This can be accomplished via suppressing critical mediators, such as functional mitochondria, aldehyde dehydrogenase (ALDH)1A, and telomere protectors (telomerase reverse transcriptase (TERT) and telomere repeat binding factor (TRF)1).

MATERIALS & METHODS

Copper nanocomplexes (diethyldithiocarbamate (DE)-Cu4O3 nanoparticles (NPs) and DE-Cu NPs) were prepared using the simplest green chemistry method and assessed for inducing mitochondrial dysfunction-dependent non-apoptotic pathway (cuproptosis) and repressing CSC markers.

RESULTS

DE-Cu4O3 NPs had higher growth inhibition for NSCLC (A549, H520, and H1299) spheroids than DE-Cu NPs. DE-Cu4O3 NPs had higher uptake rate and prooxidant effect resulting in lower mitochondrial membrane potential and mitochondrial DNA copy number, as well as stronger inhibition of telomerase and ALDH1A than DE-Cu NPs. This caused dramatic redox imbalance and lowering AKT pathway (activator of telomere stabilizers and stemness)-mediated repression of TERT and TRF1 protein levels as well as phosphorylated NF-κB subunit (p65) led to collapsing telomeres, as evidenced by downregulating TERT regulators and confocal microscopy. In animal study, this active nanocomplex revealed powerful and selective therapeutic tumor-targeting effects, with no evidence of toxicity to healthy tissues.

CONCLUSION

DE-Cu4O3 nanocomplex is deemed as promising nanomedicine for NSCLC.

Unveiling the Cuproptosis in Colitis and Colitis-Related Carcinogenesis: A Multifaceted Player and Immune Moderator

Cuproptosis represents a novel mechanism of cellular demise characterized by the intracellular buildup of copper ions. Unlike other cell death mechanisms, its distinct process has drawn considerable interest for its promising applications in managing inflammatory bowel disease (IBD) and colorectal cancer (CRC). Emerging evidence indicates that copper metabolism and cuproptosis may exert dual regulatory effects within pathological cellular environments, specifically modulating oxidative stress responses, metabolic reprogramming, and immunotherapeutic efficacy. An appropriate level of copper may promote disease progression and exert synergistic effects, but exceeding a certain threshold, copper can inhibit disease development by inducing cuproptosis in pathological cells. This makes abnormal copper levels a potential new therapeutic target for IBD and CRC. This review emphasizes the dual function of copper metabolism and cuproptosis in the progression of IBD and CRC, while also exploring the potential application of copper-based therapies in disease treatment. The analysis further delineates the modulatory influence of tumor immune microenvironment on cuproptosis dynamics, while establishing the therapeutic potential of cuproptosis-targeted strategies in circumventing resistance to both conventional chemotherapeutic agents and emerging immunotherapies. This provides new research directions for the development of future cuproptosis inducers. Finally, this article discusses the latest advances in potential molecular targets of cuproptosis and their related genes in the treatment of IBD and CRC, highlighting future research priorities and unresolved issues.

The molecular mechanism and therapeutic landscape of copper and cuproptosis in cancer

Copper, an essential micronutrient, plays significant roles in numerous biological functions. Recent studies have identified imbalances in copper homeostasis across various cancers, along with the emergence of cuproptosis, a novel copper-dependent form of cell death that is crucial for tumor suppression and therapeutic resistance. As a result, manipulating copper levels has garnered increasing interest as an innovative approach to cancer therapy. In this review, we first delineate copper homeostasis at both cellular and systemic levels, clarifying copper's protumorigenic and antitumorigenic functions in cancer. We then outline the key milestones and molecular mechanisms of cuproptosis, including both mitochondria-dependent and independent pathways. Next, we explore the roles of cuproptosis in cancer biology, as well as the interactions mediated by cuproptosis between cancer cells and the immune system. We also summarize emerging therapeutic opportunities targeting copper and discuss the clinical associations of cuproptosis-related genes. Finally, we examine potential biomarkers for cuproptosis and put forward the existing challenges and future prospects for leveraging cuproptosis in cancer therapy. Overall, this review enhances our understanding of the molecular mechanisms and therapeutic landscape of copper and cuproptosis in cancer, highlighting the potential of copper- or cuproptosis-based therapies for cancer treatment.

Discovery of Cu(II)-Dipyridophenazine Complex for Synergistic Cuproptosis/Chemodynamic Therapy via Disrupting the Tricarboxylic Acid (TCA) Cycle in Metastatic TNBC

Cuproptosis, a recently recognized regulated cell death, distinct from established death mechanisms, offers promising cancer therapy. However, its efficacy relies on intracellular copper availability and homeostasis. Herein, a novel Copper(II) dipyridohenazine complex, Cu(L1)2Cl acts as an oxidative stress amplifier and glutathione (GSH) disrupter for synergistic cuproptosis/chemodynamic anticancer therapy for the treatment of challenging triple negative breast cancer. Cu(L1)2Cl followed the endocytosis pathway to enter tumor cells and depleted GSH to release Cu+ ions which result in the production of.OH radicals generated from H2O2, leading to chemodynamic therapy. The spike in ROS generation disrupts cellular redox homeostasis, causing impaired mitochondrial function, ATP depletion, and endoplasmic reticulum stress generation. ATP depletion directly affects the function of copper-transporting ATPase 1 (ATP7A), resulting in a large amount of Cu+ trapped inside cancer cells, causing oligomerization of dihydrolipoamide S-acetyltransferase (DLAT), and depletion of Lipoyl synthase (LIAS), and leading to cellular cuproptosis. Subsequently, Cu(L1)2Cl interrupts tumor metastasis and evokes immunogenic cell death (ICD) by promoting high mobility group protein (HMGB1), ATP and lactate dehydrogenase (LDH) release, calreticulin (CRT) exposure, and inhibiting programmed death ligand 1 (PD-L1). The in vivo studies on 4T1 tumor bearing Balb/c mice validate its potent antitumor efficacy, thereby providing a new therapeutic paradigm to augment cuproptosis-related therapies.

Regulation of Different Types of Cell Death by Noncoding RNAs: Molecular Insights and Therapeutic Implications

Noncoding RNAs (ncRNAs) are crucial regulatory molecules in various biological processes, despite not coding for proteins. ncRNAs are further divided into long noncoding RNAs (lncRNAs), microRNAs (miRNAs), and circular RNAs (circRNAs) based on the size of their nucleotides. These ncRNAs play crucial roles in transcriptional, post-transcriptional, and epigenetic regulation. The regulatory roles of noncoding RNAs, including lncRNAs, miRNAs, and circRNAs, are essential in various modalities of cellular death, such as apoptosis, ferroptosis, cuproptosis, pyroptosis, disulfidptosis, and necroptosis. These noncoding RNAs are integral to modulating gene expression and protein functionality during cellular death mechanisms. In apoptosis, lncRNAs, miRNAs, and circRNAs influence the transcription of apoptotic genes. In ferroptosis, these noncoding RNAs target genes and proteins involved in iron homeostasis and oxidative stress responses. For cuproptosis, noncoding RNAs regulate pathways associated with the accumulation of copper ions, leading to cellular death. During pyroptosis, noncoding RNAs modulate inflammatory mediators and caspases, affecting the proinflammatory cell death pathway. In necroptosis, noncoding RNAs oversee the formation and functionality of necrosomes, thereby influencing the balance between cellular survival and death. Disulfidptosis is a unique type of regulated cell death caused by the excessive formation of disulfide bonds within cells, leading to cytoskeletal collapse and oxidative stress, especially under glucose-limited conditions. This investigation highlights the complex mechanisms through which noncoding RNAs coordinate cellular death, emphasizing their therapeutic promise as potential targets, particularly in the domain of cancer treatment.

Cuproptosis-related genes and agents: implications in tumor drug resistance and future perspectives

In the field of tumor treatment, drug resistance remains a significant challenge requiring urgent intervention. Recent developments in cell death research have highlighted cuproptosis, a mechanism of cell death induced by copper, as a promising avenue for understanding tumor biology and addressing drug resistance. Cuproptosis is initiated by the dysregulation of copper homeostasis, which in turn triggers mitochondrial metabolic disruptions and induces proteotoxic stress. This process specifically entails the accumulation of lipoylated proteins and the depletion of iron-sulfur cluster proteins within the context of the tricarboxylic acid cycle. Simultaneously, it is accompanied by the activation of distinct signaling pathways that collectively lead to cell death. Emerging evidence highlights the critical role of cuproptosis in addressing tumor drug resistance. However, the core molecular mechanisms of cuproptosis, regulation of the tumor microenvironment, and clinical translation pathways still require further exploration. This review examines the intersection of cuproptosis and tumor drug resistance, detailing the essential roles of cuproptosis-related genes and exploring the therapeutic potential of copper ionophores, chelators, and nanodelivery systems. These mechanisms offer promise for overcoming resistance and advancing tumor precision medicine. By elucidating the molecular mechanisms underlying cuproptosis, this study aims to identify novel therapeutic strategies and targets, thereby paving the way for the development of innovative anti-cancer drugs.

Associations between plasma and urinary heavy metal concentrations and the risk of prostate cancer

Prostate cancer is a leading cause of morbidity and mortality worldwide, with incidence rates projected to double between 2020 and 2040. This growing health challenge highlights the need for improved diagnostic strategies and risk assessment tools to better understand disease etiology and progression. Among environmental factors, heavy metals have been implicated in inflammation and carcinogenesis, yet their specific role in prostate disease remains insufficiently explored. This novel study analyses the relationship between heavy metal concentrations in plasma and urine of patients with benign prostatic hyperplasia, precancerous lesions and prostate cancer. In addition to evaluating key clinical parameters, including age, total PSA levels, hemoglobin concentrations and monocyte/lymphocyte ratio, it aims to determine whether specific heavy metals contribute to the progression of prostate disease and whether they can serve as potential biomarkers for early diagnosis. Our findings reveal significant differences in vanadium and antimony concentrations in plasma, suggesting a potential role in prostate disease pathophysiology. Notably, lower plasma antimony concentrations are associated with an increased risk of PC, while plasma vanadium concentrations are significantly higher in the PL group. Regression analysis further supports the association between heavy metal concentrations and the risk of PL and PC, highlighting the potential of vanadium and copper as biomarkers or therapeutic targets for prostate health. The study also explores the impact of lead exposure on prostate cancer risk, revealing a significant association between urine lead concentration and PC. These findings underscore the complex interaction between heavy metal concentrations and prostate disease risk, emphasizing the need for further research to elucidate underlying mechanisms and explore therapeutic interventions.

Targeted cancer therapy potential of quercetin-conjugated with folic acid-modified nanocrystalline cellulose nanoparticles: a study on AGS and A2780 cell lines

This study investigates the effects of quercetin-conjugated nanocrystalline cellulose/cetyltrimethylammonium bromide/folic acid nanoparticles (NCC/CTAB/FA NPs) on AGS and A2780 cancer cell lines, focusing on their cytotoxicity and antioxidant capacity. Dynamic light scattering (DLS) analysis revealed an average particle size of 388.70 nm, suitable for cellular uptake and release kinetics. The NCC/CTAB/FA NPs exhibited a rod and spherical morphology and uniform distribution, as confirmed by field emission scanning electron microscopy (FESEM). Fourier-transform infrared (FTIR) spectroscopy confirmed the successful synthesis and functional group integration, supporting the NPs' ability for drug delivery. The encapsulation efficiency value was 81.17%, demonstrating the effective incorporation of Quercetin. Cytotoxicity assays indicated significant reductions in cell viability for AGS and A2780 cells with IC50 values of 3.2 µg/mL and 16.04 µg/mL, respectively, while HDF cells exhibited higher viability. Flow cytometry analysis revealed a dose-dependent induction of apoptosis in AGS cells, supported by changes in gene expression related to apoptosis and inflammation. Furthermore, antioxidant capacity assays demonstrated practical free radical scavenging abilities, with IC50 values of 151.65 µg/mL for ABTS and 349.54 µg/mL for DPPH. NCC/CTAB/FA/Quercetin NPs exhibit promising characteristics for targeted cancer therapy and antioxidant applications.

Cuproptosis and its potential role in musculoskeletal disease

Cuproptosis, a recently identified form of copper-dependent cell death, arises from intracellular copper dyshomeostasis. As an essential trace element, copper plays a critical role in bioenergetic metabolism, redox regulation, and synaptic transmission. However, excessive copper exerts cytotoxic effects through multiple pathways, including increased reactive oxygen species (ROS) production, apoptotic cascade activation, necrotic membrane rupture, inflammatory responses, and mitochondrial dysfunction. Distinct from other cell death mechanisms, cuproptosis is characterized by copper ion binding to acetylated mitochondrial respiratory chain proteins, leading to pathogenic protein aggregation, iron-sulfur cluster depletion, and cellular collapse. Emerging evidence underscores aberrant copper accumulation and resultant proteotoxic stress as pivotal contributors to the pathogenesis of multiple musculoskeletal pathologies, including osteoporosis, osteoarthritis, sarcopenia, osteosarcoma, intervertebral disc degeneration, spinal cord injury, and biofilm-associated orthopedic infections. Understanding the spatiotemporal regulation of cuproptosis may provide novel opportunities for advancing diagnostic and therapeutic approaches in orthopedic medicine. This review synthesizes current insights into the molecular mechanisms of cuproptosis, its pathogenic role in musculoskeletal diseases, and the potential for biomarker-driven therapeutic interventions.

The Regulation of Trace Metal Elements in Cancer Ferroptosis

Ferroptosis, as novel type of regulated cell death that has garnered widespread attention over the past decade, has witnessed the continuous discovery of an increasing number of regulatory mechanisms. Trace metal elements play a multifaceted and crucial role in oncology. Interestingly, it has been increasingly evident that these elements, such as copper, are involved in the regulation of iron accumulation, lipid peroxidation and antiferroptotic systems, suggesting the existence of "nonferrous" mechanisms in ferroptosis. In this review, a comprehensive overview of the composition and mechanism of ferroptosis is provided. The interaction between copper metabolism (including cuproptosis) and ferroptosis in cancer, as well as the roles of other trace metal elements (such as zinc, manganese, cobalt, and molybdenum) in ferroptosis are specifically focused. Furthermore, the applications of nanomaterials based on these metals in cancer therapy are also reviewed and potential strategies for co-targeting ferroptosis and cuproptosis are explored. Nevertheless, in light of the intricate and ambiguous nature of these interactions, ongoing research is essential to further elucidate the "nonferrous" mechanisms of ferroptosis, thereby facilitating the development of novel therapeutic targets and approaches for cancer treatment.

Chlorophyllin exerts synergistic anti-tumor effect with gemcitabine in pancreatic cancer by inducing cuproptosis

Pancreatic cancer (PC) has high lethality due to multiple reasons, and its limited response to conventional chemotherapy like gemcitabine (GEM) is a non-negligible one. Therefore, our study introduces Chlorophyllin (CHL) as an effective therapeutic candidate to enhance the therapeutic efficacy of GEM. Our results demonstrate that the combination of CHL and GEM exhibits a significant synergistic anti-tumor effect by targeting multiple oncogenic processes in PC, including inhibiting cell proliferation, invasion, and migration, as well as inducing cell apoptosis. Further investigations of mechanism have revealed that CHL induces cuproptosis in PC cells through a multifaceted process, involving depleting cellular intracellular glutathione (GSH), increasing reactive oxygen species (ROS) levels, and subsequently upregulating the HSP70 protein in response to heightened oxidative stress. Additionally, CHL releases free Cu2+, binds to the Ferredoxin 1 (FDX1) protein, and ultimately leads to the oligomerization of Dihydrolipoamide S-Acetyltransferase (DLAT) proteins to amplify the copper toxicity within PC cells. Moreover, in vivo experiments have demonstrated that the combination of CHL and GEM effectively inhibits the growth of subcutaneously transplanted tumors while maintaining a favorable biosafety profile. In conclusion, our study identifies CHL as a potent enhancer of GEM's anti-tumor effects in PC through the induction of cuproptosis, thus providing a novel therapeutic avenue for patients with PC.

Cuproptosis-related gene ACAD8 inhibits the metastatic ability of colorectal cancer by inducing cuproptosis

Background

Distant metastasis of colorectal cancer (CRC) significantly impacts patient prognosis. Cuproptosis is a new form of copper ion-dependent cell death. However, whether cuproptosis-related genes (CRGs) play a role in the metastatic potential of CRC remains unclear. This study focuses on CRGs-ACAD8 to explore its role and mechanism in metastatic CRC (mCRC).

Methods

Clinical sample data from TCGA, GEO, and Fujian Provincial Hospital patients were integrated to analyze ACAD8 expression and its association with the diagnosis and prognosis of CRC. Small interfering RNA, immunohistochemistry, colony formation, wound-healing assays and so on were used to evaluate the biological functions of ACAD8. Bioinformatics was applied to investigate its relationships with immune infiltration, chemotherapy sensitivity, and signaling pathways.

Results

ACAD8 expression was significantly reduced in mCRC and demonstrated excellent diagnostic performance. Patients with high ACAD8 expression had significantly better survival. ACAD8 was closely associated with immune cell infiltration, and enhanced chemotherapy sensitivity. Pathway enrichment analysis suggested that ACAD8 might inhibit the metastasis of CRC by regulating pathways such as response to metal ions and tight junction organization. Finally, experiments confirmed a positive correlation between copper levels and ACAD8 mRNA expression, with CuCl2 upregulating ACAD8 expression. Knockdown of ACAD8 induced cuproptosis. CuCl2 inhibited the proliferation, stemness, and migratory abilities of CRC cells, while si ACAD8 attenuated these effects. Moreover, CuCl2 enhanced the sensitivity of CRC cells to oxaliplatin and 5-fluorouracil, whereas si ACAD8 diminished this chemosensitizing effect.

Conclusion

As a novel tumor suppressor, low expression of CRGs-ACAD8 is associated with the metastasis of CRC. ACAD8 holds potential diagnostic and prognostic value and may contribute to the precise treatment of CRC by regulating immune infiltration and chemotherapy sensitivity.

o8G-modified circKIAA1797 promotes lung cancer development by inhibiting cuproptosis

BACKGROUND

Lung cancer is a serious threat to human life and health, but effective screening and treatment methods are lacking. Circular RNAs (circRNAs) have important biological functions and are closely related to tumour development. Some studies have shown that the 8-oxo-7,8-dihydroguanosine (o8G) modification plays a key role in the disease process, but the effect of the o8G modification on circRNAs has not been elucidated. Moreover, cuproptosis is a novel mode of cell death in which copper ions directly promote protein aggregation and the disruption of cellular metabolic pathways. The present study revealed that the o8G modification of circKIAA1797 occurs and promotes lung cancer development by inhibiting cuproptosis, which provides new perspectives for epitranscriptomic studies and the development of novel therapeutic approaches for lung cancer.

METHODS

circRNA differential expression profiles in lung cancer were revealed via RNA high-throughput sequencing, and circKIAA1797 expression in lung cancer cell lines and tissues was detected using qPCR. Experiments such as o8G RNA immunoprecipitation (o8G RIP) and crosslinking immunoprecipitation (CLIP) were performed to explore the presence of o8G on circKIAA1797. The regulation of circKIAA1797 by the o8G reader Y-box binding protein 1 (YBX1) was explored using nuclear-cytoplasmic fractionation, actinomycin D (Act D) stability experiments and other experiments. circKIAA1797 silencing and overexpression systems were constructed for in vivo and in vitro experiments to study the role of circKIAA1797 in lung cancer development. Tagged RNA affinity purification (TRAP), RNA immunoprecipitation (RIP), coimmunoprecipitation (Co-IP), and immunofluorescence (IF) staining were subsequently conducted to reveal the molecular mechanism by which circKIAA1797 regulates cuproptosis and promotes lung cancer development.

RESULTS

This study is the first to reveal the presence of o8G on circKIAA1797 and that YBX1 is a reader that recognises ROS-induced circKIAA1797 o8G modifications and increases the stability and cytoplasmic expression of circKIAA1797. circKIAA1797, which is associated with the tumour stage and prognosis, has been shown to significantly promote the biological function of lung cancer development both in vivo and in vitro. This study revealed that circKIAA1797 inhibits intracellular cuproptosis by binding to the ferredoxin 1 (FDX1) mRNA, decreasing FDX1 mRNA stability, inhibiting FDX1 expression, and binding to the signal transducer and activator of transcription 1 (STAT1) protein and inhibiting lipoyltransferase 1 (LIPT1) transcription; moreover, circKIAA1797 promotes the closure of the mitochondrial permeability transition pore (mPTP), inhibits cuproptosis, and ultimately promotes lung cancer development.

CONCLUSIONS

This study revealed the presence of the o8G modification in circKIAA1797, which plays an important role in the development of lung cancer. circKIAA1797 can inhibit cuproptosis by inhibiting key cuproptosis proteins and promoting mPTP closure, ultimately promoting the development of lung cancer. This study provides not only a new theoretical basis for an in-depth understanding of the molecular mechanisms of lung cancer development but also a potential target for lung cancer treatment.

Shikonin-Cu(II) Supramolecular Polymers Exhibit Antitumor Activity via Necrosis and Cuproptosis

Supramolecular polymers driven by the metal-ligand coordination possess reversible bonds, making them promising candidates for integrating the therapeutic functions of metal ions and small-molecule drugs, and subsequently releasing these components within cells after endocytosis. In this study, a kind of supramolecular polymer, SHICU, is developed, composed of Shikonin ligand and Cu(II) ion. Upon reduction by intracellular glutathione (GSH), SHICU dissociates to release Shikonin, Cu(II), and SHICU fragments. The released Shikonin and Cu(II) exhibit a synergistic antitumor effect through the reactive oxygen species (ROS)-dependent necrosis. Meanwhile, the released SHICU that remains structural integrity induces a distinct antitumor mechanism by triggering cuproptosis in tumor cells. This dual functionality, combining ROS-dependent necrosis and cuproptosis, highlights the potential of SHICU in advancing antitumor therapies, while the integration of supramolecular polymers with the emerging cell death mechanism of cuproptosis facilitates the development of innovative cancer drugs.

Characterization of Active Compounds in Sanhuang Shu'ai Decoction for the Management of Ulcerative Colitis: A UHPLC-MS Study

OBJECTIVE

The effectiveness of Sanhuang Shu'ai decoction (SSD), a traditional Chinese medicine used to treat diarrhea and colitis, especially ulcerative colitis (UC), is not well understood regarding how its chemical components work.

METHODS

This research used ultra-high-performance liquid chromatography (UHPLC)-tandem mass spectrometry (MS), network pharmacology, and molecular docking to understand the active substances and potential mechanisms of SSD in treating UC.

RESULTS

UHPLC and MS analyses identified 710 active components in SSD extracts (ZYTQY) and 387 in SSD-containing serum (HYXQ), with 35 active compounds found in both ZYTQY and HYXQ and 67 active compounds from SSDD (SSD compound obtained directly from the database), along with 6 metabolites that may be key components in its function. Subsequently, we used PubChem, DrugBank, and TTD to identify 108 potential targets from SSDD, and 27 hub genes were found by constructing the PPI network. GO and KEGG pathway analyses confirmed that SSDD may be effective in treating UC through the PI3K/AKT and HIF-1 signaling pathways. The pathway analysis of 4 metabolites in SSD highlights the continued importance of the PI3K/AKT pathway. Molecular docking and simulations indicate that baicalein, oroxylin A, quercetin, and wogonin may aid in treating UC by regulating the MAPK3 and NFKB1 genes. Baicalein interacts with several specific targets, including EGFR, MAPK1, MAPK3, NFKB1, PTGS2, and TP53.

CONCLUSIONS

SSD treats UC through various compounds and pathways targeting multiple areas, whereas baicalein specifically promotes intestinal repair in UC by modulating EGFR-PI3K/AKT/NFκB, EGFR/PI3K/AKT-/TP53, and EGFR/PI3K/A KT/MAPK signaling pathways.

Strategies to combat cancer drug resistance: focus on copper metabolism and cuproptosis

Cancer cells often develop tolerance to chemotherapy, targeted therapy, and immunotherapy drugs either before or during treatment. The significant heterogeneity among various tumors poses a critical challenge in modern cancer research, particularly in overcoming drug resistance. Copper, as an essential trace element in the body, participates in various biological processes of diseases, including cancers. The growth of many types of tumor cells exhibits a heightened dependence on copper. Thus, targeting copper metabolism or inducing cuproptosis may be potential ways to overcome cancer drug resistance. Copper chelators have shown potential in overcoming cancer drug resistance by targeting copper-dependent processes in cancer cells. In contrast, copper ionophores, copper-based nanomaterials, and other small molecules have been used to induce copper-dependent cell death (cuproptosis) in cancer cells, including drug-resistant tumor cells. This review summarizes the regulation of copper metabolism and cuproptosis in cancer cells and the role of copper metabolism and cuproptosis in cancer drug resistance, providing ideas for overcoming cancer resistance in the future.

M6A-modified BFSP1 induces aerobic glycolysis to promote liver cancer growth and metastasis through upregulating tropomodulin 4

RNA N6-methyladenosine (m6A) is a common RNA modification in eukaryotes, and its abnormal regulation is closely related to cancer progression. Aerobic glycolysis is a main way for cancer cells to obtain energy. It was found that beaded filament structural protein 1 (BFSP1) is a m6A related gene in liver cancer. However, the effect of m6A-modified BFSP1 on aerobic glycolysis and how it is regulated in liver cancer progression have not been explored. Here, we found that BFSP1 was upregulated in liver cancer cells and tissues. Overexpression of BFSP1 promoted the viability, invasion, and aerobic glycolysis of liver cancer cells, whereas knockdown of BFSP1 showed the opposite effects. Co-immunoprecipitation, immunofluorescence and GST pull down analyses showed that BFSP1 directly interacted with tropomodalin 4 (TMOD4), and knockdown of TMOD4 reversed BFSP1 overexpression-induced malignant phenotypes and aerobic glycolysis in liver cancer cells. Moreover, methyltransferase-like 3 (METTL3) enhanced BFSP1 stability by augmenting m6A modification of BFSP1 mRNA, which is achieved in a YTHDF1-dependent manner. In vivo experiments in mice confirmed that METTL3 increased BFSP1 stability by promoting m6A modification of BFSP1 mRNA, and knockdown of BFSP1 inhibited tumor growth and metastasis. In summary, METTL3-mediated m6A methylation of BFSP1 mRNA plays an important role in the aerobic glycolysis and progression of liver cancer, providing a potential therapeutic strategy for liver cancer.

Role of the sulfur-containing amino acid-ROS axis in cancer chemotherapeutic drug resistance

Chemotherapeutic drug resistance remains a major barrier to effective cancer treatment. Drug resistance could be driven in part by adaptive redox remodeling of cancer cells. Paradoxically, drug-resistant malignancies exhibit elevated reactive oxygen species (ROS), as well as amplified antioxidant defenses, which enable cancer cell survival under therapeutic stress. Central to this adaptation is glutathione (GSH), the predominant cellular antioxidant, whose synthesis relies on sulfur-containing amino acids (SAAs) - methionine and cysteine. This review delineates the metabolic interplay between methionine and cysteine in the transsulfuration pathway, highlighting their roles as precursors in GSH biosynthesis. We systematically summarize the key enzymes that drive GSH production and their contributions to resistance against platinum-based drugs and other chemotherapeutics. In addition to GSH synthesis, we summarize the roles of GSH antioxidant systems, including glutathione peroxidases (GPXs), peroxiredoxins (PRDXs), and thioredoxins (TRXs), which are critical in chemotherapeutic drug resistance through ROS scavenging. Recent advances reveal that targeting these enzymes, by pharmacologically inhibiting transsulfuration enzymes or disrupting GSH-dependent antioxidant cascades, can sensitize resistant cancer cells to ROS-mediated therapies. These findings not only clarify the mechanistic links between SAA metabolism and redox adaptation but also provide practical approaches to overcome chemotherapeutic drug resistance. By analyzing metabolic and redox vulnerabilities, this review highlights the therapeutic potential to restore chemosensitivity, offering new options in precision oncology medicine.

Cell death in tumor microenvironment: an insight for exploiting novel therapeutic approaches

Cell death is critical in tumor biology. The common cancer therapies can cause cell death and alleviate tumor, while the cancer cells can develop a resistance to cell death and survive from the therapies. Thus, not only observing the alternative mechanisms of tumor cells resistant to cell death, but also understanding the intricate dynamics of cell death processes within the tumor microenvironment (TME), are essential for tailoring effective therapeutic strategies. High-throughput sequencing technologies have revolutionized cancer research by enabling comprehensive molecular profiling. Recent advances in single cell sequencing have unraveled the heterogeneity of TME components, shedding light on their complex interactions. In this review, we explored the interplay between cell death signaling and the TME, summarised the potential drugs inducing cell death in pre-clinical stage, reviewed some studies applying next-generation sequencing technologies in cancer death research, and discussed the future utilization of updated sequencing platforms in screening novel treatment methods targeted cell death. In conclusion, leveraging multi-omics technologies to dissect cell death signaling in the context of the TME holds great promise for advancing cancer research and therapy development.

Epigallocatechin Gallate Promotes Cuproptosis via the MTF1/ATP7B Axis in Hepatocellular Carcinoma

BACKGROUND

Cuproptosis is a form of copper-dependent non-apoptotic cell death. Cancer cells that prefer to use aerobic glycolysis for energy generation are commonly insensitive to cuproptosis, which hinders its application for cancer treatment. Epigallocatechin gallate (EGCG) possesses diverse pharmacological activities. However, the association between EGCG and cuproptosis has not been studied.

METHODS

The cell viability, proliferation, and cuproptosis-related protein levels were detected to investigate whether EGCG enhances the sensitivity of HCC cells to cuproptosis. The intracellular copper level, related copper metabolism proteins, and gene expression were detected to explore the mechanisms. In addition, a nude mouse xenograft model was established to determine the effects of EGCG on cuproptosis in tumor tissues.

RESULTS

The combination of EGCG and copper ionophores significantly enhanced the mortality of HCC cells and heightened the sensitivity of HCC cells to cuproptosis. There was a notable reduction in the expression of copper export protein copper-transporting P-type ATPase (ATP7B). EGCG effectively suppressed metal regulatory transcription factor (MTF1) expression and subsequently hindered the transcriptional regulation of ATP7B. EGCG also facilitated the intratumoral accumulation of copper and augmented susceptibility to cuproptosis in vivo.

CONCLUSIONS

EGCG can increase the sensitivity of hepatocellular carcinoma cells to cuproptosis by promoting intracellular copper accumulation through the MTF1/ATP7B axis.

Cu-Mn nanocomposite for enhanced tumor cuproptosis achieved by remodeling the tumor microenvironment and activating the antitumor immunogenic responses

Cuproptosis is a newly discovered mode of cell death, which is caused by excess copper and results in cell death via the mitochondrial pathway. However, the complex tumor microenvironment (TME) is characterized by many factors, including high levels of glutathione and lack O2, limit the application of traditional cuproptosis agents in antitumor therapy. Herein, we report a hyaluronic acid modified copper-manganese composite nanomedicine (CMCNs@HA) to remodel the TME and facilitate efficient cuproptosis in tumor. The integration of CuO2 and MnO2 into CMCNs@HA endows this nanoplatform to generate O2 and deplete GSH in tumor site, ensuring the environment is beneficial to the cuproptosis of tumor. The glutathione (GSH) depletion process is accompanied by the release of Mn2+ ions. The released Mn2+ ions improve the cuproptosis through efficient chemodynamic therapy and initiate immune response via activating the cyclic GMP-AMP synthase-stimulator of interferon genes (cGAS-STING) pathway, which significantly suppresses tumor growth and inhibits tumor metastases. In addition, the Mn2+ ions release process enables this nanoplatform to work as activable T1 contrast agent to achieve accurate tumor diagnosis. This functionally complementary composite metal nanomaterial may provide effective ideas regarding the application of cuproptosis in designing tumor therapeutic regimens. STATEMENT OF SIGNIFICANCE: Cuproptosis in combination with cGAS-STING offers significant potential for tumor treatment. Here, we constructed TME responsive copper-manganese composite nanomaterials (CMCNs@HA) to augment tumor cuproptosis. GSH depletion, hypoxia relief, and effective chemodynamic therapy caused by CMCNs@HA facilitate the progression of cuproptosis. Besides, CMCNs@HA successfully initiate immune response via activating the cyclic GMP-AMP synthase-stimulator of interferon genes pathway and significantly inhibits tumor metastases. Simultaneously, released Mn2+ ions provide real-time magnetic resonance imaging (MRI) signal changes, enabling accurate tumor diagnosis and monitoring of the therapeutic process.

Pharmacologically Targeting Ferroptosis and Cuproptosis in Neuroblastoma

Neuroblastoma is a deadly pediatric cancer that originates from the neural crest and frequently develops in the abdomen or adrenal gland. Although multiple approaches, including chemotherapy, radiotherapy, targeted therapy, and immunotherapy, are recommended for treating neuroblastoma, the tumor will eventually develop resistance, leading to treatment failure and cancer relapse. Therefore, a firm understanding of the molecular mechanisms underlying therapeutic resistance is vital for the development of new effective therapies. Recent research suggests that cancer-specific modifications to multiple subtypes of nonapoptotic regulated cell death (RCD), such as ferroptosis and cuproptosis, contribute to therapeutic resistance in neuroblastoma. Targeting these specific types of RCD may be viable novel targets for future drug discovery in the treatment of neuroblastoma. In this review, we summarize the core mechanisms by which the inability to properly execute ferroptosis and cuproptosis can enhance the pathogenesis of neuroblastoma. Therefore, we focus on emerging therapeutic compounds that can induce ferroptosis or cuproptosis, delineating their beneficial pharmacodynamic effects in neuroblastoma treatment. Cumulatively, we suggest that the pharmacological stimulation of ferroptosis and ferroptosis may be a novel and therapeutically viable strategy to target neuroblastoma.

Rational design of peptides to overcome drug resistance by metabolic regulation

Chemotherapy is widely used clinically, however, its efficacy is often compromised by the development of drug resistance, which arises from prolonged administration of drugs or other stimuli. One of the driven causes of drug resistance in tumors or bacterial infections is metabolic reprogramming, which alters mitochondrial metabolism, disrupts metabolic pathways and causes ion imbalance. Bioactive peptide materials, due to their biocompatibility, diverse bioactivities, customizable sequences, and ease of modification, have shown promise in overcoming drug resistance. This review provides an in-depth analysis of metabolic reprogramming and associated microenvironmental changes that contribute to drug resistance in common tumors and bacterial infections, suggesting potential therapeutic targets. Additionally, we explore peptide-based materials for regulating metabolism and their potential synergic effect with other therapies, highlighting the mechanisms by which these peptides reverse drug resistance. Finally, we discuss future perspectives and the clinical challenges in peptide-based treatments, aiming to offer insights for overcoming drug-resistant diseases.

Aberrant DNA methylation as a key modulator of cell death pathways: insights into cancer progression and other diseases

Cell death plays a significant role in the physiology of all living organisms, and its disruption is the underlying cause of various diseases. Previously, it was assumed that apoptosis and necrosis were the only means of cell death. Recent discoveries of alternative cell death pathways highlighted a complicated interplay between cell death regulation and its role in numerous human pathologies. DNA methylation is a universal epigenetic mechanism characterized by the covalent addition of a methyl group to cytosine in CpG dinucleotides. Alterations in DNA methylation patterns lead to the dysregulation of multiple cell death pathways. DNA methylome studies on cell death pathways have improved our understanding of the mechanism of various types of cell death, such as apoptosis, pyroptosis, necroptosis, ferroptosis, anoikis, autophagy, and cuproptosis. The irregular DNA methylation patterns of genes encoding proteins linked to multiple cell death pathways could underlie resistance to cell death. Dysregulation of cell death is linked to ailments in humans, such as cancer. However, unlike genetic alterations, DNA methylation is reversible, making it extremely interesting for therapeutics considering the potential use of DNA methyltransferase inhibitors. Furthermore, tumor microenvironment and genetic heterogeneity of cancers may influence the methylation-dependent regulation of cell death, contributing to tumor progression and therapeutic resistance. Understanding how DNA methylation influences cell death pathways may illuminate the underlying causes of cancer. This review explores the significance of the DNA methylation patterns of key genes involved in cell death pathways, emphasizing their connections and identifying potential gaps that could be exploited for developing epigenetic therapies targeting cancer.

Role of circular RNAs in cancer therapy resistance

Over the past decade, circular RNAs (circRNAs) have gained recognition as a novel class of genetic molecules, many of which are implicated in cancer pathogenesis via different mechanisms, including drug resistance, immune escape, and radio-resistance. ExosomalcircRNAs, in particular, facilitatecommunication between tumour cells and micro-environmental cells, including immune cells, fibroblasts, and other components. Notably, micro-environmental cells can reportedly influence tumour progression and treatment resistance by releasing exosomalcircRNAs. circRNAs often exhibit tissue- and cancer-specific expression patterns, and growing evidence highlights their potential clinical relevance and utility. These molecules show strong promise as potential biomarkers and therapeutic targets for cancer diagnosis and treatment. Therefore, this review aimed to briefly discuss the latest findings on the roles and resistance mechanisms of key circRNAs in the treatment of various malignancies, including lung, breast, liver, colorectal, and gastric cancers, as well as haematological malignancies and neuroblastoma.This review will contribute to the identification of new circRNA biomarkers for the early diagnosis as well as therapeutic targets for the treatment of cancer.

Impact of cuproptosis in gliomas pathogenesis with targeting options

Gliomas constitute the most prevalent primary central nervous system tumors, often characterized by complex metabolic profile, genomic instability, and aggressiveness, leading to frequent relapse and high mortality rates. Traditional treatments are commonly ineffective because of gliomas increased heterogeneity, invasive characteristics and resistance to chemotherapy. Among several pathways affecting cellular homeostasis, cuproptosis has recently emerged as a novel type of programmed cell death, triggered by accumulation of copper ions. Although the precise molecular mechanisms of cuproptosis are not fully elucidated, there is evidence that copper ions can target mitochondrial lipoylated proteins, disrupting the tricarboxylic acid cycle and electron transport chain, thus leading to deregulated mitochondrial metabolism, protein aggregation and cell death. Of importance, altered expression of copper transporters and abnormally high intracellular copper levels have been observed in several cancer types, including gliomas, contributing to tumor growth and metastasis. Furthermore, a range of prognostic models incorporating cuproptosis-related genes and lncRNAs have been proposed and are currently under clinical validation. Drugs modulating cuproptosis or interfering with copper-binding proteins are under development, causing metabolic failure and cell death, thus offering potential new avenues for glioma diagnosis and therapy. In this article, we explore the role of copper metabolism in gliomas and the potential synergistic effects of cuproptosis-based treatments with current therapies, in effective targeting of tumor progression and chemoresistance.

Glycolysis reprogramming in CAFs promotes oxaliplatin resistance in pancreatic cancer through circABCC4 mediated PKM2 nuclear translocation

Cancer-associated fibroblasts (CAFs) play a key role in oxaliplatin resistance in pancreatic ductal adenocarcinoma (PDAC). However, the potential mechanisms by which CAFs promote chemotherapy resistance have not yet been explored. In this study, we found that circABCC4 (hsa_circ_0030582) was positively correlated with poor platinum-chemotherapeutic response and a shorter progression-free survival (PFS) time in late-stage PDAC patients. CircABCC4 enhanced the ability of CAFs to induce oxaliplatin resistance in pancreatic cancer cells through glycolysis reprogramming. Mechanistically, circABCC4 enhanced the interaction between PKM2 and KPNA2 to promote PKM2 nuclear translocation in CAFs, leading to the transcription of glycolysis-related genes. The glycolytic reprogramming of CAFs promoted the secretion of IL-8, which in turn enhanced DNA damage repair in pancreatic cancer. Blocking PKM2 nuclear translocation abolished circABCC4-driven oxaliplatin resistance of pancreatic cancer in vivo. Collectively, our study reveals a circRNA-mediated glycolysis reprogramming of CAFs to induce oxaliplatin resistance and highlights circABCC4 as a potential therapeutic target.

SRF/SLC31A1 signaling promotes cuproptosis induced by celastrol in NSCLC

Faced with the highly malignant challenge of lung cancer, traditional chemotherapeutic agents, although predominantly inducing apoptosis, are severely limited in their therapeutic effect by the overexpression of anti-apoptotic proteins in lung cancer. Recently discovered copper-induced non-apoptotic cell death, known as cuproptosis, represents a novel mechanism for regulating cell death. Whether Celastrol (Cel), a potential anti-tumor drug, can counter non-small cell lung cancer (NSCLC) through inducing cuproptosis remains to be thoroughly investigated. This study demonstrates that the copper chelator tetrathiomolybdate (TTM) is more effective in rescuing Cel-induced NSCLC cell death compared to other inhibitors. RNA sequencing revealed that Cel significantly upregulates the copper transporter protein SLC31A1. In addition, Cel also promotes intracellular copper accumulation, reduces GSH levels, and exhibits features of cuproptosis, including loss of iron-sulfur cluster proteins (FDX1, SDHB, POLD1), increased HSP70, and DLAT oligomerization. Experiments also found that Cel significantly increases reactive oxygen species (ROS) levels, reduces mitochondrial membrane potential, and lowers ATP levels. It was predicted through online databases that SRF may be the transcription factor for SLC31A1, and this was validated through overexpression experiments. In vivo data demonstrated that Cel significantly inhibits tumor growth without damaging the heart, liver, or kidneys of mice. This study first reveals that celastrol disrupts intracellular copper homeostasis through the SRF/SLC31A1 pathway, promoting cuproptosis in NSCLC cells, providing support for Cel as a potential safe and effective chemotherapeutic agent.

Aprocitentan mitigates doxorubicin-induced cardiotoxicity by inhibiting cuproptosis, oxidative stress, and mitochondrial impairments via the activation of sirtuin 7

Doxorubicin (DOX) is a widely used chemotherapy drug for cancer while leads to several cardiac disorders including cardiomyopathy and heart failure. Aprocitentan is a novel dual endothelin-1 receptor antagonist and functions as an effective antihypertensive drug for resistant hypertension. However, the exact roles of aprocitentan in DOX-induced cardiotoxicity remains largely unclear.In this work, we explored potential participants of aprocitentan in DOX-induced cardiotoxicity. Mice were treated with DOX to induce cardiotoxicity, and then received either aprocitentan or tetrathiomolybdate interventions respectively. Compared with controls, DOX-treated mice exhibited cardiac impairments and dysfunction. Notably, aprocitentan or tetrathiomolybdate intervention remarkably mitigated DOX-mediated cardiac cardiotoxicity, as evidenced by alleviated myocardial fibrosis and improved cardiac function. Furthermore, aprocitentan or tetrathiomolybdate administration significantly mitigated myocardial cuproptosis, oxidative stress, cardiac aging and inflammation in DOX-treated mice with decreased levels of DLAT accumulation, as well as downregulated expressions of HSP70, P16 and P21, respectively. In cultured primary rat cardiomyocytes, treatment with aprocitentan alleviated DOX-induced augmentation of cuproptosis and oxidative stress with reduced DLAT accumulation. Moreover, aprocitentan administration strikingly reversed DOX-induced and elesclomol-aggravated cellular senescence and mitochondrial injury in cardiomyocytes. More importantly, knock-down of sirtuin 7 (SIRT7) by SIRT7 siRNA blocked the beneficial effects of aprocitentan on DOX-associated cuproptosis, oxidative stress, mitochondrial injury, and senescence in cardiomyocytes. In summary, aprocitentan exerts as a novel therapeutic agent for alleviation of DOX-induced cardiotoxicity through the inhibition of cuproptosis, oxidative stress, cardiac aging and mitochondrial injuries via the activation of SIRT7, offering new possibilities for prevention and treatment of DOX-induced cardiac disorders.

Biometallic ions and derivatives: a new direction for cancer immunotherapy

Biometallic ions play a crucial role in regulating the immune system. In recent years, cancer immunotherapy has become a breakthrough in cancer treatment, achieving good efficacy in a wide range of cancers with its specificity and durability advantages. However, existing therapies still face challenges, such as immune tolerance and immune escape. Biometallic ions (e.g. zinc, copper, magnesium, manganese, etc.) can assist in enhancing the efficacy of immunotherapy through the activation of immune cells, enhancement of tumor antigen presentation, and improvement of the tumor microenvironment. In addition, biometallic ions and derivatives can directly inhibit tumor cell progression and offer the possibility of effectively overcoming the limitations of current cancer immunotherapy by promoting immune responses and reducing immunosuppressive signals. This review explores the role and potential application prospects of biometallic ions in cancer immunotherapy, providing new ideas for future clinical application of metal ions as part of cancer immunotherapy and helping to guide the development of more effective and safe therapeutic regimens.

Targeting the initiator to activate both ferroptosis and cuproptosis for breast cancer treatment: progress and possibility for clinical application

Breast cancer is the most commonly diagnosed cancer worldwide. Metal metabolism is pivotal for regulating cell fate and drug sensitivity in breast cancer. Iron and copper are essential metal ions critical for maintaining cellular function. The accumulation of iron and copper ions triggers distinct cell death pathways, known as ferroptosis and cuproptosis, respectively. Ferroptosis is characterized by iron-dependent lipid peroxidation, while cuproptosis involves copper-induced oxidative stress. They are increasingly recognized as promising targets for the development of anticancer drugs. Recently, compelling evidence demonstrated that the interplay between ferroptosis and cuproptosis plays a crucial role in regulating breast cancer progression. This review elucidates the converging pathways of ferroptosis and cuproptosis in breast cancer. Moreover, we examined the value of genes associated with ferroptosis and cuproptosis in the clinical diagnosis and treatment of breast cancer, mainly outlining the potential for a co-targeting approach. Lastly, we delve into the current challenges and limitations of this strategy. In general, this review offers an overview of the interaction between ferroptosis and cuproptosis in breast cancer, offering valuable perspectives for further research and clinical treatment.

In Situ Transformable Fibrillar Clusters Disrupt Intracellular Copper Metabolic Homeostasis by Comprehensive Blockage of Cuprous Ions Efflux

Dysregulation of copper metabolism is intricately associated with the occurrence and therapeutic management of colorectal cancer. Previous studies have attempted to induce cuproptosis by delivering lethal doses of copper ions into tumor cells, often with systemic safety risks. In vivo, transformable peptide is modular and designed for various tumor-related proteins, which can affect protein function and distribution. Here, a fibrillar transformation peptidic (FTP) nanoparticle is synthesized, which can bind ATP7B membrane proteins (cuprous ions transporter) and transform into nanofibrils/ATP7B clusters, inducing "copper-free cuproptosis" in vivo. Without adding exogenous copper ions, the spherical FTP nanoparticles bound the high distribution regions of ATP7B membrane proteins, transforming into fibrillar networks in situ with prolonged retention. The cage-like fibrillar network would further capture unbound or newly generated free ATP7B membrane proteins, thereby significantly and consistently preventing cuprous ions efflux. The FTP nanoparticles would not undergo in situ fibrillar transformation on the low expression region of ATP7B membrane proteins but enter the cell for safe degradation, which exhibited high specificity and safety in vivo. By disrupting intracellular copper homeostasis, the transformable fibrillar clusters displayed a long-term anti-tumor effect on subcutaneous transplantation and liver metastatic CRC models.

Development of a prognostic gene signature and exploration of P4HA1 in the modulation of cuproptosis in colorectal cancer

Cuproptosis, a newly identified form of cell death, has drawn increasing attention for its association with various cancers, though its specific role in colorectal cancer (CRC) remains unclear. In this study, transcriptomic and clinical data from CRC patients available in the TCGA database were analyzed to investigate the impact of cuproptosis. Differentially expressed genes linked to cuproptosis were identified using Weighted Gene Co-Expression Network Analysis (WGCNA). Key genes were further refined through LASSO regression and random forest approaches, culminating in the development of a prognostic model comprising six critical genes. The predictive accuracy of the model was validated using two independent external datasets. This model effectively stratified patients into high- and low-risk groups, which exhibited significant differences in disease stage, immune landscape, tumor mutational burden, and therapeutic response, underscoring the robustness of the model. P4HA1 was identified as a key gene of interest, where downregulation was found to inhibit tumor progression in single-cell sequencing analyses and in vitro experiments. Additionally, suppression of P4HA1 enhanced the sensitivity of CRC cells to the cuproptosis inducer elesclomol (ES), potentially through oxidative stress mechanisms. In conclusion, this study proposes a prognostic model based on six cuproptosis-related genes that could aid in personalizing CRC treatment. Furthermore, P4HA1 emerges as a promising therapeutic target.

Potential involvement of cuproptosis induced by m6A-modified autophagy gene ATG10 in KICH : Cuproptosis induced by m6A-modified ATG10 in KICH

Kidney Chromophobe (KICH) is the third most prevalent renal malignancy, with research challenges due to a dearth of cell lines and clinical samples. There is no specific treatment regimen tailored exclusively for KICH. This study employed gene expression analysis, immunohistochemistry (IHC), Spearman's correlation, immune cell infiltration assessment, and molecular network construction to investigate the autophagy gene ATG10 in KICH. ATG10 was uniquely downregulated in KICH, predominantly regulated by RNA m6A methylation. This downregulation correlated with patient survival, suggesting a potential tumor-regulatory role. ATG10's involvement in the protein lipidation pathway, essential for cuproptosis, was identified. B cells and CD8 + T cells were key immune cells in KICH tumorigenesis associated with ATG10. Examination of molecular networks identified several key molecules and mechanisms, including ceRNA, interplaying proteins, and transcription factors. Additionally, drug targeting analysis pointed to specific amino acids and metabolites as potential therapeutic agents. This study elucidates the significance of ATG10 in KICH, implicating m6A methylation and cuproptosis as novel targets for therapeutic intervention. The identification of B cells and CD8 + T cells as key immune components, along with specific amino acids, suggests that a combination of targeted immune therapies and dietary interventions could provide a multifaceted approach to KICH treatment. Given the limited understanding of KICH pathogenesis, our analysis has unveiled new theoretical insights and potential clinical significances for KICH, expected to broaden the research horizon in this field.

Mitochondrial pathways of copper neurotoxicity: focus on mitochondrial dynamics and mitophagy

Copper (Cu) is essential for brain development and function, yet its overload induces neuronal damage and contributes to neurodegeneration and other neurological disorders. Multiple studies demonstrated that Cu neurotoxicity is associated with mitochondrial dysfunction, routinely assessed by reduction of mitochondrial membrane potential. Nonetheless, the role of alterations of mitochondrial dynamics in brain mitochondrial dysfunction induced by Cu exposure is still debatable. Therefore, the objective of the present narrative review was to discuss the role of mitochondrial dysfunction in Cu-induced neurotoxicity with special emphasis on its influence on brain mitochondrial fusion and fission, as well as mitochondrial clearance by mitophagy. Existing data demonstrate that, in addition to mitochondrial electron transport chain inhibition, membrane damage, and mitochondrial reactive oxygen species (ROS) overproduction, Cu overexposure inhibits mitochondrial fusion by down-regulation of Opa1, Mfn1, and Mfn2 expression, while promoting mitochondrial fission through up-regulation of Drp1. It has been also demonstrated that Cu exposure induces PINK1/Parkin-dependent mitophagy in brain cells, that is considered a compensatory response to Cu-induced mitochondrial dysfunction. However, long-term high-dose Cu exposure impairs mitophagy, resulting in accumulation of dysfunctional mitochondria. Cu-induced inhibition of mitochondrial biogenesis due to down-regulation of PGC-1α further aggravates mitochondrial dysfunction in brain. Studies from non-brain cells corroborate these findings, also offering additional evidence that dysregulation of mitochondrial dynamics and mitophagy may be involved in Cu-induced damage in brain. Finally, Cu exposure induces cuproptosis in brain cells due mitochondrial proteotoxic stress, that may also contribute to neuronal damage and pathogenesis of certain brain diseases. Based on these findings, it is assumed that development of mitoprotective agents, specifically targeting mechanisms of mitochondrial quality control, would be useful for prevention of neurotoxic effects of Cu overload.

Metal-based smart nanosystems in cancer immunotherapy

Metals are an emerging topic in cancer immunotherapy that have shown great potential in modulating cancer immunity cycle and promoting antitumor immunity by activating the intrinsic immunostimulatory mechanisms which have been identified in recent years. The main challenge of metal-assisted immunotherapy lies in the fact that the free metals as ion forms are easily cleared during circulation, and even cause systemic metal toxicity due to the off-target effects. With the rapid development of nanomedicine, metal-based smart nanosystems (MSNs) with unique controllable structure become one of the most promising delivery carriers to solve the issue, owing to their various endogenous/external stimuli-responsiveness to release free metal ions for metalloimmunotherapy. In this review, the state-of-the-art research progress in metal-related immunotherapy is comprehensively summarized. First, the mainstream mechanisms of MSNs-assisted immunotherapy will be delineated. The immunological effects of certain metals and categorization of MSNs with different characters and compositions are then provided, followed by the representative exemplar applications of MSNs in cancer treatment, and synergistic combination immunotherapy. Finally, we conclude this review with a summary of the remaining challenges associated with MSNs and provide the authors' perspective on their further advances.

BIRC5 knockdown ameliorates hepatocellular carcinoma progression via regulating PPARγ pathway and cuproptosis

BACKGROUND

Hepatocellular carcinoma (HCC) with complex molecular carcinogenesis represents a kind of prevalent neoplasm occurring in the liver. The objective of this study is to illustrate the function of baculoviral inhibitor of apoptosis repeat containing 5 (BIRC5) and underlying action mechanisms in HCC progression.

METHODS

Comprehensive bioinformatics methods were conducted to screen differentially expressed genes (DEGs), cuproptosis-associated DEGs, and hub genes. The correlation between BIRC5 and immune cell infiltration, prognosis value was evaluated. The specific effects of BIRC5 silencing on HCC cells was validated by functional assays, and the impact on tumorigenicity and cuproptosis was also elucidated in vivo. Additionally, the effects of BIRC5 deficiency on PPAR pathway were determined using Oroxin A in vitro.

RESULTS

A total of 45 cuproptosis-associated DEGs and 9 hub genes were discovered through bioinformatics. Then 6 core genes were confirmed in Hep-3B and SK-Hep-1 cells with 4 genes upregulated and 2 genes downregulated. Therein, BIRC5 was positively correlated with the infiltration of CD8+ T cells, macrophages, and highly expressed BIRC5 exhibited poor prognosis of overall survival in HCC. Furthermore, BIRC5 deletion inhibited the PPARγ pathway, thereby restraining the malignant phenotypes of HCC cells and tumorigenesis in vivo. Additionally, silencing of BIRC5 contributed to the initiation of cuproptosis in HCC.

CONCLUSIONS

BIRC5 silencing attenuated HCC through blocking PPARγ pathway and regulating cuproptosis, which may offer therapeutic implications against HCC.

Cuproptosis and Cuproptosis-Based Synergistic Therapy for Cancer Treatment

Copper, as an essential trace nutrient for human, plays a crucial role in numerous cellular activities, and is vital for maintaining homeostasis in organisms. Deviations from normal intracellular copper concentration range can disrupt the cellular homeostasis and lead to cell death. Cell death is the process in which cells lose their vitality and cannot sustain normal metabolism, which has various forms. The recently discovered cuproptosis mechanism differs from the previously recognized forms, which is triggered by intracellular copper accumulation. The discovery of cuproptosis has sparked interest among researchers, and this mechanism has been applied in the treatment of various intractable diseases, including different types of cancer. However, the developed cuproptosis-based therapies have revealed certain limitations, such as low immunostimulatory efficiency, poor tumor targeting, and inhibition by the tumor microenvironment. Therefore, researchers are devoted to combining cuproptosis with existing cancer therapies to develop more effective synergistic cancer therapies. This review summarizes the latest research advancements in the cuproptosis-based therapies for various types of cancer, with a focus on the synergistic cancer therapies. Finally, it provides an outlook on the future development of cuproptosis in anti-tumor therapy.

Unveiling Cuproptosis: Mechanistic insights, roles, and leading advances in oncology

Copper, a vital micronutrient, performs essential functions in numerous biological settings. Its disrupted metabolism is implicated in both the initiation of tumors and therapeutic interventions for cancer, underscoring the critical necessity of preserving copper homeostasis. Cuproptosis, a regulated cell death (RCD) modulated by copper, is activated in response to elevated copper concentrations, prompting an investigation into its implication in oncogenesis. Within this review, an exploration is conducted into copper dynamics and homeostasis maintenance within cells. Furthermore, it delves into the mechanisms underlying cuproptosis and its interplay with signaling pathways implicated in cancer. The potential synergy between cuproptosis and ferroptosis and its impact on tumor immunomodulation is discussed. Additionally, promising avenues for addressing cuproptosis in cancer involve assessing the utility of copper chelators and ionophores. By addressing pressing questions surrounding cuproptosis and outlining its pivotal role in cancer pathogenesis and treatment, this review propounds targeting cuproptosis as a promising frontier in antitumor therapy, potentially revolutionizing cancer treatment strategies.

The mode of action of sorafenib in MDA-MB-231 breast carcinoma cells involves components of apoptotic, necroptotic and autophagy-dependent cell death pathways

We report the identification of an interesting mode of action by sorafenib (SF) (Nexavar) in triple-negative breast adenocarcinoma MDA-MB-231 cells. The dying cells presented features of apoptosis, such as externalization of phosphatidylserine and cleaved caspase-3, and autophagy-mediated cell death, such as formation of autophagosomes and autolysosomes, the overexpression of LC3-II, and the presence of LAMP1-positive vacuoles, while displaying insufficient autophagic flux. Components of endoplasmic reticulum stress (ER stress; PERK and CHOP) and of necroptosis (p-MLKL) were also elevated considerably. Investigating potential target proteins that could modulate this form of cell death, we next investigated the role of tubulin disruption, which is known to induce necroptosis, apoptosis, and autophagy-dependent cell death. Interactions of SF with purified tubulin were investigated in detail using a combination of cellular and biophysical assays, transmission electron microscopy, and computer simulations. A marked reduction in the intrinsic tryptophan fluorescence of tubulin, a concentration-dependent elevation of anilinonaphthalene sulfonate-tubulin complex fluorescence, electron micrographs of deformed in vitro-assembled microtubules, and disrupted and hyper-stabilized cellular microtubules evinced the ability of SF to target tubulin and disrupt cellular microtubules. Molecular docking and molecular dynamic simulations positioned the drug between the α and β subunits of tubulin with considerable stability (ΔGbind, -31.43 kcal/mol), suggesting that drug-induced perturbation of tubulin could contribute to this mode of cell death.

Phenanthroline and phenyl carboxylate mixed ligand copper complexes in developing drugs to treat cancer

The success of a classic inorganic coordination compound, Cisplatin, cis-[Pt(NH3)2Cl2], as the first anticancer metallodrug started a field of research dedicated to discovering coordination compounds with antitumor activity, encompassing various metals. Among these, copper complexes have emerged as interesting candidates to develop drugs to treat cancer. In this work, mixed ligand complexes of Cu(II) with diimines (phenanthroline or 4-methylphenanthroline) and 3-(4-hydroxyphenyl)propanoate, phenylcarboxylate or phenylacetate were synthesized. They were characterized in the solid state, including a new crystal structure of [Cu2(3-(4-hydroxyphenyl)propanoate)3(phenanthroline)2]Cl·H2O. The obtained complexes presented a variety of stoichiometries. In solution, complexes were partially dissociated in the corresponding Cu-diimine complex. The complexes bound to the DNA by partial intercalation and groove binding, as assessed by Circular Dichroism, relative viscosity change and UV-Vis titration. The cytotoxicity of the complexes was determined in vitro on MDA-MB-231, MCF-7 (human metastatic breast adenocarcinomas, the first triple negative), MCF-10A (breast nontumoral), A549 (human lung epithelial carcinoma), and MRC-5 (human nontumoral lung epithelial cells), finding an activity higher than that of Cisplatin, although with less selectivity.

Un-methylation of NUDT21 represses docosahexaenoic acid biosynthesis contributing to enzalutamide resistance in prostate cancer

AIMS

The recent approval of enzalutamide for metastatic castration-sensitive prostate cancer underscores its growing clinical significance, raising concerns about emerging resistance and limited treatment options. While the reactivation of the androgen receptor (AR) and other genes plays a role in enzalutamide resistance, identifications of novel underlying mechanism with therapeutic potential in enzalutamide-resistant (EnzaR) cells remain largely elusive.

METHODS

Drug-resistant prostate cancer cell lines, animal models, and organoids were utilized to examine NUDT21 function by transcriptomic and metabolomic analyses through loss-of-function and gain-of-function assays. Notably, a mono-methylation monoclonal antibody and conditional-knockin transgenic mouse model of NUDT21 were generated for evaluating its function.

RESULTS

NUDT21 overexpression acts as a crucial alternative polyadenylation (APA) mediator, supported by its oncogenic role in prostate cancer. PRMT7-mediated mono-methylation of NUDT21 induces a shift in 3'UTR usage, reducing oncogenicity. In contrast, its un-methylation promotes cancer growth and cuproptosis insensitivity in EnzaR cells by exporting toxic copper and suppressing docosahexaenoic acid (DHA) biosynthesis. Crucially, NUDT21 inhibition or DHA supplementation with copper ionophore holds therapeutic promise for EnzaR cells.

CONCLUSIONS

The un-methylation of NUDT21-mediated 3'UTR shortening unveils a novel mechanism for enzalutamide resistance, and our findings offer innovative strategies for advancing the treatment of prostate cancer patients experiencing enzalutamide resistance.

Copper and Colorectal Cancer

Minerals constitute only 5% of the typical human diet but are vital for health and functionality. Copper, a trace element, is absorbed by the human gut at 30-40% from diets typical of industrialized countries. The liver produces metallothioneins, which store copper. Copper is crucial for mitochondrial respiration, pigmentation, iron transport, antioxidant defense, hormone production, and extracellular matrix biosynthesis. Copper deficiency, often caused by mutations in the ATP7A gene, results in Menkes disease, an X-linked recessive disorder. On the contrary, Wilson disease is characterized by toxic copper accumulation. Cuproptosis, a unique form of cell death regulated by copper, is a subtype of necrosis induced by enhanced mitochondrial metabolism and intracellular copper accumulation. This process can reduce the malignant potential of tumor cells by inhibiting glucose metabolism. Therapeutically, copper and its complexes have shown efficacy in malignancy treatments. The disruption of copper homeostasis and excessive cuproplasia are significant in colorectal cancer development and metastasis. Therefore, manipulating copper status presents a potential therapeutic target for colorectal cancer, using copper chelators to inhibit copper formation or copper ion carriers to promote cuproptosis. This review highlights the role of copper in human physiology and pathology, emphasizing its impact on colorectal cancer and potential therapeutic strategies. Future AI-based approaches are anticipated to accelerate the development of new compounds targeting cuproptosis and copper disruption in colorectal cancer.

Copper homeostasis and copper-induced cell death in tumor immunity: implications for therapeutic strategies in cancer immunotherapy

Copper is an important trace element for maintaining key biological functions such as cellular respiration, nerve conduction, and antioxidant defense. Maintaining copper homeostasis is critical for human health, and its imbalance has been linked to various diseases, especially cancer. Cuproptosis, a novel mechanism of copper-induced cell death, provides new therapeutic opportunities for metal ion regulation to interact with cell fate. This review provides insights into the complex mechanisms of copper metabolism, the molecular basis of cuproptosis, and its association with cancer development. We assess the role of cuproptosis-related genes (CRGs) associated with tumorigenesis, their importance as prognostic indicators and therapeutic targets, and the impact of copper homeostasis on the tumor microenvironment (TME) and immune response. Ultimately, this review highlights the complex interplay between copper, cuproptosis, and cancer immunotherapy.

The role of cuproptosis in gastric cancer

As a biologically essential transition metal, copper is widely involved in various enzymatic reactions and crucial biological processes in the body. It plays an increasingly important role in maintaining normal cellular metabolism and supporting the growth and development of the human body. As a trace element, copper maintains the dynamic balance of its concentration in body fluids through active homeostatic mechanisms. Both excess and deficiency of copper ions can impair cell function, ultimately leading to cell damage and death. Cuproptosis is a novel form of cell death where copper ions cause cell death by directly binding to the lipoylated components of the citric acid cycle (CAC) in mitochondrial respiration and interfering with the levels of iron-sulfur cluster (Fe-S cluster) proteins, ultimately causing protein toxic stress. Its primary characteristics are Cu2+ concentration dependence and high expression in mitochondrial respiratory cells. Recent research has revealed that, compared to other forms of programmed cell death such as apoptosis, necrosis, and autophagy, cuproptosis has unique morphological and biochemical features. Cuproptosis is associated with the occurrence and development of various diseases, including cancer, neurodegenerative diseases, and cardiovascular diseases. This article focuses on a review of the relevance of cuproptosis in gastric cancer (GC).

Hollow Calcium/Copper Bimetallic Amplifier for Cuproptosis/Paraptosis/Apoptosis Cancer Therapy via Cascade Reinforcement of Endoplasmic Reticulum Stress and Mitochondrial Dysfunction

The endoplasmic reticulum (ER) and mitochondria are essential organelles that play crucial roles in maintaining cellular homeostasis. The simultaneous induction of ER stress and mitochondrial dysfunction represents a promising yet challenging strategy for cancer treatment. Herein, a hollow calcium-copper bimetallic nanoplatform is developed as a cascade amplifier to reinforce ER stress and mitochondrial dysfunction for breast cancer treatment. For this purpose, we report a facile method for preparing hollow CaCO3 (HCC) nanoparticles by regulating the dissolution-recrystallization process of amorphous CaCO3, and the amplifier D@HCC-CuTH is meticulously fabricated by sequentially coating disulfiram-loaded HCC nanoparticles with a copper coordination polymer and hyaluronan. In tumor cells, the dithiocarbamate-copper complex generated in situ by liberated disulfiram and Cu2+ inhibits the ubiquitin-proteasome system, causing irreversible ER stress and intracellular Ca2+ redistribution. Meanwhile, the amplifier induces mitochondrial dysfunction via triggering a self-amplifying loop of mitochondrial Ca2+ burst, and reactive oxygen species augment. Additionally, Cu2+ induces dihydrolipoamide S-acetyltransferase oligomerization in mitochondria, further exacerbating mitochondrial damage via cuproptosis. Collectively, ER stress amplification and mitochondrial dysfunction synergistically induce a cuproptosis-paraptosis-apoptosis trimodal cell death pathway, which demonstrates significant efficacy in suppressing tumor growth. This study presents a paradigm for synchronously inducing subcellular organelle disorders to boost cancer multimodal therapy.