Copper is taken up efficiently from albumin and alpha2-macroglobulin by cultured human cells by more than one mechanism

Cuproptosis in cancer: biological implications and therapeutic opportunities

Cuproptosis, a newly identified copper (Cu)-dependent form of cell death, stands out due to its distinct mechanism that sets it apart from other known cell death pathways. The molecular underpinnings of cuproptosis involve the binding of Cu to lipoylated enzymes in the tricarboxylic acid cycle. This interaction triggers enzyme aggregation and proteotoxic stress, culminating in cell death. The specific mechanism of cuproptosis has yet to be fully elucidated. This newly recognized form of cell death has sparked numerous investigations into its role in tumorigenesis and cancer therapy. In this review, we summarized the current knowledge on Cu metabolism and its link to cancer. Furthermore, we delineated the molecular mechanisms of cuproptosis and summarized the roles of cuproptosis-related genes in cancer. Finally, we offered a comprehensive discussion of the most recent advancements in Cu ionophores and nanoparticle delivery systems that utilize cuproptosis as a cutting-edge strategy for cancer treatment.

Copper in colorectal cancer: From copper-related mechanisms to clinical cancer therapies

Copper, a trace element and vital cofactor, plays a crucial role in the maintenance of biological functions. Recent evidence has established significant correlations between copper levels, cancer development and metastasis. The strong redox-active properties of copper offer both benefits and disadvantages to cancer cells. The intestinal tract, which is primarily responsible for copper uptake and regulation, may suffer from an imbalance in copper homeostasis. Colorectal cancer (CRC) is the most prevalent primary cancer of the intestinal tract and is an aggressive malignant disease with limited therapeutic options. Current research is primarily focused on the relationship between copper and CRC. Innovative concepts, such as cuproplasia and cuproptosis, are being explored to understand copper-related cellular proliferation and death. Cuproplasia is the regulation of cell proliferation that is mediated by both enzymatic and nonenzymatic copper-modulated activities. Whereas, cuproptosis refers to cell death induced by excess copper via promoting the abnormal oligomerisation of lipoylated proteins within the tricarboxylic acid cycle, as well as by diminishing the levels of iron-sulphur cluster proteins. A comprehensive understanding of copper-related cellular proliferation and death mechanisms offers new avenues for CRC treatment. In this review, we summarise the evolving molecular mechanisms, ranging from abnormal intracellular copper concentrations to the copper-related proteins that are being discovered, and discuss the role of copper in the pathogenesis, progression and potential therapies for CRC. Understanding the relationship between copper and CRC will help provide a comprehensive theoretical foundation for innovative treatment strategies in CRC management.

Cysteine Rich Intestinal Protein 2 is a copper-responsive regulator of skeletal muscle differentiation

Copper (Cu) is an essential trace element required for respiration, neurotransmitter synthesis, oxidative stress response, and transcriptional regulation. Imbalance in Cu homeostasis can lead to several pathological conditions, affecting neuronal, cognitive, and muscular development. Mechanistically, Cu and Cu-binding proteins (Cu-BPs) have an important but underappreciated role in transcription regulation in mammalian cells. In this context, our lab investigates the contributions of novel Cu-BPs in skeletal muscle differentiation using murine primary myoblasts. Through an unbiased synchrotron X-ray fluorescence-mass spectrometry (XRF/MS) metalloproteomic approach, we identified the murine cysteine rich intestinal protein 2 (mCrip2) in a sample that showed enriched Cu signal, which was isolated from differentiating primary myoblasts derived from mouse satellite cells. Immunolocalization analyses showed that mCrip2 is abundant in both nuclear and cytosolic fractions. Thus, we hypothesized that mCrip2 might have differential roles depending on its cellular localization in the skeletal muscle lineage. mCrip2 is a LIM-family protein with 4 conserved Zn2+-binding sites. Homology and phylogenetic analyses showed that mammalian Crip2 possesses histidine residues near two of the Zn2+-binding sites (CX2C-HX2C) which are potentially implicated in Cu+-binding and competition with Zn2+. Biochemical characterization of recombinant human hsCRIP2 revealed a high Cu+-binding affinity for two and four Cu+ ions and limited redox potential. Functional characterization using CRISPR/Cas9-mediated deletion of mCrip2 in primary myoblasts did not impact proliferation, but impaired myogenesis by decreasing the expression of differentiation markers, possibly attributed to Cu accumulation. Transcriptome analyses of proliferating and differentiating mCrip2 KO myoblasts showed alterations in mRNA processing, protein translation, ribosome synthesis, and chromatin organization. CUT&RUN analyses showed that mCrip2 associates with a select set of gene promoters, including MyoD1 and metallothioneins, acting as a novel Cu-responsive or Cu-regulating protein. Our work demonstrates novel regulatory functions of mCrip2 that mediate skeletal muscle differentiation, presenting new features of the Cu-network in myoblasts.

Revolutionizing breast cancer treatment: Harnessing the related mechanisms and drugs for regulated cell death (Review)

Breast cancer arises from the malignant transformation of mammary epithelial cells under the influence of various carcinogenic factors, leading to a gradual increase in its prevalence. This disease has become the leading cause of mortality among female malignancies, posing a significant threat to the health of women. The timely identification of breast cancer remains challenging, often resulting in diagnosis at the advanced stages of the disease. Conventional therapeutic approaches, such as surgical excision, chemotherapy and radiotherapy, exhibit limited efficacy in controlling the progression and metastasis of the disease. Regulated cell death (RCD), a process essential for physiological tissue cell renewal, occurs within the body independently of external influences. In the context of cancer, research on RCD primarily focuses on cuproptosis, ferroptosis and pyroptosis. Mounting evidence suggests a marked association between these specific forms of RCD, and the onset and progression of breast cancer. For example, a cuproptosis vector can effectively bind copper ions to induce cuproptosis in breast cancer cells, thereby hindering their proliferation. Additionally, the expression of ferroptosis‑related genes can enhance the sensitivity of breast cancer cells to chemotherapy. Likewise, pyroptosis‑related proteins not only participate in pyroptosis, but also regulate the tumor microenvironment, ultimately leading to the death of breast cancer cells. The present review discusses the unique regulatory mechanisms of cuproptosis, ferroptosis and pyroptosis in breast cancer, and the mechanisms through which they are affected by conventional cancer drugs. Furthermore, it provides a comprehensive overview of the significance of these forms of RCD in modulating the efficacy of chemotherapy and highlights their shared characteristics. This knowledge may provide novel avenues for both clinical interventions and fundamental research in the context of breast cancer.

Metalloproteins and metalloproteomics in health and disease

Metalloproteins represents more than one third of human proteome, with huge variation in physiological functions and pathological implications, depending on the metal/metals involved and tissue context. Their functions range from catalysis, bioenergetics, redox, to DNA repair, cell proliferation, signaling, transport of vital elements, and immunity. The human metalloproteomic studies revealed that many families of metalloproteins along with individual metalloproteins are dysregulated under several clinical conditions. Also, several sorts of interaction between redox- active or redox- inert metalloproteins are observed in health and disease. Metalloproteins profiling shows distinct alterations in neurodegenerative diseases, cancer, inflammation, infection, diabetes mellitus, among other diseases. This makes metalloproteins -either individually or as families- a promising target for several therapeutic approaches. Inhibitors and activators of metalloenzymes, metal chelators, along with artificial metalloproteins could be versatile in diagnosis and treatment of several diseases, in addition to other biomedical and industrial applications.

Copper Metabolism and Cuproptosis: Molecular Mechanisms and Therapeutic Perspectives in Neurodegenerative Diseases

Copper is an essential trace element, and plays a vital role in numerous physiological processes within the human body. During normal metabolism, the human body maintains copper homeostasis. Copper deficiency or excess can adversely affect cellular function. Therefore, copper homeostasis is stringently regulated. Recent studies suggest that copper can trigger a specific form of cell death, namely, cuproptosis, which is triggered by excessive levels of intracellular copper. Cuproptosis induces the aggregation of mitochondrial lipoylated proteins, and the loss of iron-sulfur cluster proteins. In neurodegenerative diseases, the pathogenesis and progression of neurological disorders are linked to copper homeostasis. This review summarizes the advances in copper homeostasis and cuproptosis in the nervous system and neurodegenerative diseases. This offers research perspectives that provide new insights into the targeted treatment of neurodegenerative diseases based on cuproptosis.

Copper in Cancer: from transition metal to potential target

In recent years, with the continuous in-depth exploration of the molecular mechanisms of tumorigenesis, numerous potential new targets for cancer treatment have been identified, some of which have been further developed in clinical practice and have produced positive outcomes. Notably, researchers' initial motivation for studying copper metabolism in cancer stems from the fact that copper is a necessary trace element for organisms and is closely connected to body growth and metabolism. Moreover, over the past few decades, considerable progress has been made in understanding the molecular processes and correlations between copper and cancer. Certain achievements have been made in the development and use of relevant clinical medications. The concept of "cuproptosis," a novel concept that differs from previous forms of cell death, was first proposed by a group of scientists last year, offering fresh perspectives on the targeting capabilities of copper in the treatment of cancer. In this review, we introduced the fundamental physiological functions of copper, the key components of copper metabolism, and a summary of the current research contributions on the connection between copper and cancer. In addition, the development of new copper-based nanomaterials and their associated mechanisms of action are discussed. Finally, we described how the susceptibility of cancer cells to this metallic nutrition could be leveraged to further improve the existing cancer treatment paradigm in the new setting.

Copper in Gynecological Diseases

Copper (Cu) is an essential micronutrient for the correct development of eukaryotic organisms. This metal plays a key role in many cellular and physiological activities, including enzymatic activity, oxygen transport, and cell signaling. Although the redox activity of Cu is crucial for enzymatic reactions, this property also makes it potentially toxic when found at high levels. Due to this dual action of Cu, highly regulated mechanisms are necessary to prevent both the deficiency and the accumulation of this metal since its dyshomeostasis may favor the development of multiple diseases, such as Menkes' and Wilson's diseases, neurodegenerative diseases, diabetes mellitus, and cancer. As the relationship between Cu and cancer has been the most studied, we analyze how this metal can affect three fundamental processes for tumor progression: cell proliferation, angiogenesis, and metastasis. Gynecological diseases are characterized by high prevalence, morbidity, and mortality, depending on the case, and mainly include benign and malignant tumors. The cellular processes that promote their progression are affected by Cu, and the mechanisms that occur may be similar. We analyze the crosstalk between Cu deregulation and gynecological diseases, focusing on therapeutic strategies derived from this metal.

Current and Future of "Turn-On" Based Small-Molecule Copper Probes for Cuproptosis

Increasing evidence shows that abnormal copper (Cu) metabolism is highly related to many diseases, such as Alzheimer's disease, Wilson's disease, hematological malignancies and Menkes disease. Very recently, cuproptosis, a Cu-dependent, programmed cell death was firstly described by Tsvetkov et al. in 2022. Their findings may provide a new perspective for the treatment of related diseases. However, the concrete mechanisms of these diseases, especially cuproptosis, remain completely unclear, the reason of which may be a lack of reliable tools to conduct highly selective, sensitive and high-resolution imaging of Cu in complex life systems. So far, numerous small-molecular fluorescent probes have been designed and utilized to explore the Cu signal pathway. Among them, fluorescence turn-on probes greatly enhance the resolution and accuracy of imaging and may be a promising tool for research of investigation into cuproptosis. This review summarizes the probes developed in the past decade which have the potential to study cuproptosis, focusing on the design strategies, luminescence mechanism and biological-imaging applications. Besides, we put forward some ideas concerning the design of next-generation probes for cuproptosis, aiming to tackle the main problems in this new field. Furthermore, the prospect of cuproptosis in the treatment of corresponding diseases is also highlighted.

Antioxidant 1 copper chaperone gene expression and copper levels in dog osteosarcoma patients

Twenty-four dogs with OS underwent limb amputation. Serum, OS tumour, and normal bone were harvested at time of surgery. RNA was extracted and gene expression was performed using quantitative polymerase chain reaction (qPCR). Tissue and blood copper concentrations were also determined with spectrophotometry. Compared to bone, tumour samples had significantly higher expressions of antioxidant 1 copper chaperone (ATOX1, p = .0003). OS tumour copper levels were significantly higher than that of serum (p < .010) and bone (p = .038). Similar to our previous observations in mouse and human OS, dog OS demonstrates overexpression of genes that regulate copper metabolism (ATOX1), and subsequent copper levels. Dogs with OS may provide a robust comparative oncology platform for the further study of these factors, as well as potential pharmacologic interventions.

Proteome analysis, bioinformatic prediction and experimental evidence revealed immune response down-regulation function for serum-starved human fibroblasts

Emerging evidence indicates that fibroblasts play pivotal roles in immunoregulation by producing various proteins under health and disease states. In the present study, for the first time, we compared the proteomes of serum-starved human skin fibroblasts and peripheral blood mononuclear cells (PBMCs) using Nano-LC-ESI-tandem mass spectrometry. This analysis contributes to a better understanding of the underlying molecular mechanisms of chronic inflammation and cancer, which are intrinsically accompanied by growth factor deficiency.The proteomes of starved fibroblasts and PBMCs consisted of 307 and 294 proteins, respectively, which are involved in lymphocyte migration, complement activation, inflammation, acute phase response, and immune regulation. Starved fibroblasts predominantly produced extracellular matrix-related proteins such as collagen/collagenase, while PBMCs produced focal adhesion-related proteins like beta-parvin and vinculin which are involved in lymphocyte migration. PBMCs produced a more diverse set of inflammatory molecules like heat shock proteins, while fibroblasts produced human leukocytes antigen-G and -E that are known as main immunomodulatory molecules. Fifty-four proteins were commonly found in both proteomes, including serum albumin, amyloid-beta, heat shock cognate 71 kDa, and complement C3. GeneMANIA bioinformatic tool predicted 418 functions for PBMCs, including reactive oxygen species metabolic processes and 241 functions for starved fibroblasts such as antigen processing and presentation including non-classical MHC -Ib pathway, and negative regulation of the immune response. Protein-protein interactions network analysis indicated the immunosuppressive function for starved fibroblasts-derived human leucocytes antigen-G and -E. Moreover, in an in vitro model of allogeneic transplantation, the immunosuppressive activity of starved fibroblasts was experimentally documented.

Conclusion

Under serum starvation-induced metabolic stress, both PBMCs and fibroblasts produced molecules like heat shock proteins and amyloid-beta, which can have pathogenic roles in auto-inflammatory diseases such as rheumatoid arthritis, type 1 diabetes mellitus, systemic lupus erythematosus, aging, and cancer. However, starved fibroblasts showed immunosuppressive activity in an in vitro model of allogeneic transplantation, suggesting their potential to modify such adverse reactions by down-regulating the immune system.

Correlation between copper speciation and transport pathway in Caco-2 cells

BACKGROUND

Previous studies have demonstrated that, in contrast to the properties of food-derived copper, water-derived copper exerts neurotoxic effects and exhibits different speciation during digestion. The cellular uptake efficiencies of different speciation of copper are distinct. However, it is unclear whether these different speciation share the same transport pathway in intestinal epithelial cells. In the present study, the intracellular accumulation of copper derived from copper ion and copper complex solutions was investigated in Caco-2 cells.

RESULTS

The cellular accumulation of copper derived from copper ions was higher than that of copper derived from the copper complex. Treatment with carboplatin and Ag⁺ , which are copper transporter receptor 1 (Ctr1, LC31A1) inhibitors, did not inhibit copper accumulation in Caco-2 cells, but inhibited copper accumulation in HepG2 cells. Zinc ion significantly decreased the intracellular copper content from 114 ± 7 μg g^-1 protein to 88 ± 4 μg g^-1 protein in the copper ion-treated Caco-2 cells, but not in the copper complex-treated Caco-2 cells (84.6 ± 14 μg g^-1 protein versus 87.7 ± 20 μg g^-1 protein, P > 0.05). Additionally, copper accumulation in Caco-2 and HepG2 cells significantly differed depending on different solvents (Hanks' balanced salt solution and NaNO₃ , P < 0.05).

CONCLUSION

These results indicate that the intracellular accumulation of copper derived from copper ion and copper complex is mediated by distinct copper transport pathways. Copper speciation may be an important factor that affects copper absorption and toxicity. © 2022 Society of Chemical Industry.

Properties of recombinant extracellular N-terminal domain of human high-affinity copper transporter 1 (hNdCTR1) and its interactions with Cu(II) and Ag(I) ions

High-affinity copper transporter 1 (CTR1) is a key link in the transfer of copper (Cu) from the extracellular environment to the cell. Violation in the control system of its expression, or mutations in this gene, cause a global copper imbalance. However, the mechanism of copper transfer via CTR1 remains unclear. It has been shown that transformed bacteria synthesizing the fused GB1-NdCTR become resistant to toxic silver ions. According to UV-Vis spectrophotometry and isothermal titration calorimetry, electrophoretically pure GB1-NdCTR specifically and reversibly binds copper and silver ions, and binding is associated with aggregation. Purified NdCTR1 forms SDS-resistant oligomers. The link between nontrivial properties of NdCTR1 and copper import mechanism from extracellular space, as well as potential chelating properties of NdCTR1, are discussed.

Exploration of the Potential Role of Serum Albumin in the Delivery of Cu(I) to Ctr1

Human serum albumin (HSA) is the major copper (Cu) carrier in blood. The majority of previous studies that have investigated Cu interactions with HSA have focused primarily on the Cu(II) oxidation state. Yet, cellular Cu uptake by the human copper transport protein (Ctr1), a plasma membrane-embedded protein responsible for Cu uptake into cells, requires Cu(I). Recent in vitro work has determined that reducing agents, such as the ascorbate present in blood, are sufficient to reduce the Cu(II)HSA complex to form Cu(I)HSA and that Cu(I) is bound to HSA with pM affinity. The biological accessibility of Cu(I)HSA suggests that HSA-bound Cu(I) may be an unappreciated form of Cu cargo and a key player in extracellular Cu trafficking. To better understand Cu trafficking by HSA, we sought to investigate the exchange of Cu(I) from HSA to a model peptide of the Cu-binding ectodomain of Ctr1. In this study, we used X-ray absorption near-edge spectroscopy to show that Cu(I) becomes more highly coordinated as increasing amounts of the Ctr_1-14 model peptide are added to a solution of Cu(I)HSA. Extended X-ray absorption fine structure (EXAFS) spectroscopy was used to further characterize the interaction of Cu(I)HSA with Ctr_1-14 by determining the ligands coordinating Cu(I) and their bond lengths. The EXAFS data support that some Cu(I) likely undergoes complete transfer from HSA to Ctr_1-14. This finding of HSA interacting with and releasing Cu(I) to an ectodomain model peptide of Ctr1 suggests a mechanism by which HSA delivers Cu(I) to cells under physiological conditions.

Pan-cancer analyses reveal molecular and clinical characteristics of cuproptosis regulators

Imbalance in copper homeostasis can be lethal. A recent study found that excess copper induces cell death in a way that has never been characterized before, which is dependent on mitochondrial stress and is referred to as "cuproptosis." The role of cuproptosis in tumors has not yet been elucidated. In this study, we revealed the complex and important roles of cuproptosis regulators and cuproptosis activity in tumors via a comprehensive analysis of multiomics data from more than 10,000 samples of 33 tumor types. We found that the cyclin-dependent kinase inhibitor 2A is the most frequently altered cuproptosis regulator, and the cuproptosis regulator expression is dysregulated in various tumors. Additionally, we developed a cuproptosis activity score to reflect the overall cuproptosis level. On the basis of the expression levels of cuproptosis regulators, tumors can be divided into two clusters with different cuproptosis activities and survival outcomes. Importantly, cuproptosis activity was found to be associated with the prognosis of multiple tumors and multiple tumor-related pathways, including fatty acid metabolism and remodeling of the tumor microenvironment. Furthermore, cuproptosis increased the sensitivity to multiple drugs and exhibited potential to predict the outcome of immunotherapy. We also comprehensively identified cuproptosis-related microRNAs, long noncoding RNAs, and transcription factors. We provided the code corresponding to the results of this study in GitHub (https://github.com/Changwuuu/Cuproptosis-pancancer.git) for reference. In summary, this study reveals important molecular and clinical characteristics of cuproptosis regulators and cuproptosis activity in tumors, and suggests the use of cuproptosis as a promising tumor therapeutic approach. This study provides an important reference point for future cuproptosis-related research.

Copper homeostasis and cuproptosis in health and disease

As an essential micronutrient, copper is required for a wide range of physiological processes in virtually all cell types. Because the accumulation of intracellular copper can induce oxidative stress and perturbing cellular function, copper homeostasis is tightly regulated. Recent studies identified a novel copper-dependent form of cell death called cuproptosis, which is distinct from all other known pathways underlying cell death. Cuproptosis occurs via copper binding to lipoylated enzymes in the tricarboxylic acid (TCA) cycle, which leads to subsequent protein aggregation, proteotoxic stress, and ultimately cell death. Here, we summarize our current knowledge regarding copper metabolism, copper-related disease, the characteristics of cuproptosis, and the mechanisms that regulate cuproptosis. In addition, we discuss the implications of cuproptosis in the pathogenesis of various disease conditions, including Wilson's disease, neurodegenerative diseases, and cancer, and we discuss the therapeutic potential of targeting cuproptosis.

Comprehensive analysis of cuproptosis-related genes and tumor microenvironment infiltration characterization in breast cancer

Background

Cuproptosis is a newly discovered programmed cell death dependent on overload copper-induced mitochondrial respiration dysregulation. The positive response to immunotherapy, one of the most important treatments for invasive breast cancer, depends on the dynamic balance between tumor cells and infiltrating lymphocytes in the tumor microenvironment (TME). However, cuproptosis-related genes (CRGs) in clinical prognosis, immune cell infiltration, and immunotherapy response remain unclear in breast cancer progression.

Methods

The expression and mutation patterns of 12 cuproptosis-related genes were systematically evaluated in the BRCA training group. Through unsupervised clustering analysis and developing a cuproptosis-related scoring system, we further explored the relationship between cuproptosis and breast cancer progression, prognosis, immune cell infiltration, and immunotherapy.

Results

We identified two distinct CuproptosisClusters, which were correlated with the different patterns between clinicopathological features, prognosis, and immune cell infiltration. Moreover, the differences of the three cuproptosis-related gene subtypes were evaluated based on the CuproptosisCluster-related DEGs. Then, a cuproptosis-related gene signature (PGK1, SLC52A2, SEC14L2, RAD23B, SLC16A6, CCL5, and MAL2) and the scoring system were constructed to quantify the cuproptosis pattern of BRCA patients in the training cohort, and the testing cohorts validated them. Specifically, patients from the low-CRG_score group were characterized by higher immune cell infiltration, immune checkpoint expression, immune checkpoint inhibitor (ICI) scores, and greater sensitivity to immunotherapy. Finally, we screened out RAD23B as a favorable target and indicated its expression was associated with breast cancer progression, drug resistance, and poor prognosis in BRCA patients by performing real-time RT-PCR, cell viability, and IC50 assay.

Conclusions

Our results confirmed the essential function of cuproptosis in regulating the progression, prognosis, immune cell infiltration, and response to breast cancer immunotherapy. Quantifying cuproptosis patterns and constructing a CRG_score could help explore the potential molecular mechanisms of cuproptosis regulating BRCA advancement and provide more effective immunotherapy and chemotherapy targets.

Comprehensive Analysis of Cuproptosis-Related Genes in Immune Infiltration and Prognosis in Melanoma

Skin cutaneous melanoma (SKCM, hereafter referred to as melanoma) is the most lethal skin cancer with increasing incidence. Regulated cell death plays an important role in tumorigenesis and serves as an important target for almost all treatment strategies. Cuproptosis is the most recently identified copper-dependent regulated cell death form that relies on mitochondria respiration. However, its role in tumorigenesis remains unknown. The correlation of cuproptosis-related genes with tumor prognosis is far to be understood, either. In the present study, we explored the correlation between cuproptosis-related genes with the prognosis of melanoma by accessing and analyzing a public database and found 11 out 12 genes were upregulated in melanoma tissues and three genes (LIPT1, PDHA1, and SLC31A1) have predictive value for the prognosis. The subgroup of melanoma patients with higher cuproptosis-related gene expression showed longer overall survival than those with lower gene expression. We chose LIPT1 for further exploration. LIPT1 expression was increased in melanoma biopsies and was an independent favorable prognostic indicator for melanoma patients. Moreover, LIPT1 expression was positively correlated with PD-L1 expression and negatively associated with Treg cell infiltration. The melanoma patients with higher LIPT1 expression showed longer overall survival than those with lower LIPT1 expression after receiving immunotherapy, indicating the prognostic predictive value of LIPT1. Finally, a pan-cancer analysis indicated that LIPT1 was differentially expressed in diverse cancers as compared to normal tissues and correlated with the expression of multiple immune checkpoints, especially PD-L1. It could serve as a favorable prognosis indicator in some cancer types. In conclusion, our study demonstrated the prognostic value of cuproptosis-related genes, especially LIPT1, in melanoma, and revealed the correlation between LIPT1 expression and immune infiltration in melanoma, thus providing new clues on the prognostic assessment of melanoma patients and providing a new target for the immunotherapy of melanoma.

Construction of pH-sensitive targeted micelle system co-delivery with curcumin and dasatinib and evaluation of anti-liver cancer

Nanomedicine delivery systems can achieve precise drug delivery and reduce toxic side effects compared with traditional drug delivery methods, but further development is still needed to eliminate obstacles such as multiple drug co-delivery, uncontrolled drug-release, and drug-resistance. Herein, we designed a dual drug-loaded nanosystem (THCD-NPs) that selectively transports and targets tumor cells for the treatment of liver cancer. In this drug delivery system, hyaluronic acid (HA)-conjugated curcumin (Cur) and d-α-tocopherol acid polyethylene glycolsuccinate (TPGS) were used as selective drug-carrying vehicles to deliver dasatinib (DAS) to cancer cells for combined administration. The mean size of the nanoparticles was approximately 66.14 ± 4.02 nm with good in vitro stability. The nanoparticles were pH sensitive and could accelerate drug release at low pH conditions. In vitro experiments showed that THCD-NPs were significantly cytotoxic to HepG2 cells and could be effectively taken up by these cells. Detailed investigations also demonstrated its pro-apoptotic activity. In vivo NIR fluorescence imaging showed that the nanoparticles could accumulate efficiently at the tumor site. Meanwhile, in vivo experiments showed that THCD-NPs significantly inhibited tumor growth and reduced the toxic side effects of free drugs in a mouse solid tumor model. In short, the nanoparticles we prepared provide a new idea for the treatment of liver cancer.

Secretion and Uptake of Copper via a Small Copper Carrier in Blood Fluid

Studies with Wilson disease model mice that accumulate excessive copper, due to a dysfunctional ATP7B “copper pump” resulting in decreased biliary excretion, showed that the compensatory increase in urinary copper loss was due to a small copper carrier (∼1 kDa) (SCC). We show here that SCC is also present in the blood plasma of normal and Wilson disease model mice and dogs, as determined by ultrafiltration and size exclusion chromatography (SEC). It is secreted by cultured hepatic and enterocytic cells, as determined by pretreatment with ⁶⁷Cu nitrilotriacetate (NTA) or nonradioactive 5–10 μM Cu-NTA, and collecting and examining 3 kDa ultrafiltrates of the conditioned media, where a single major copper peak is detected by SEC. Four different cultured cell types exposed to the radiolabeled SCC all took up the ⁶⁷Cu at various rates. Rates differed somewhat when uptake was from Cu-NTA. Uptake of SCC-⁶⁷Cu was inhibited by excess nonradioactive Cu(I) or Ag(I) ions, suggesting competition for uptake by copper transporter 1 (CTR1). Knockout of CTR1 in fibroblasts reduced uptake rates by 60%, confirming its participation, but also involvement of other transporters. Inhibitors of endocytosis, or an excess of metal ions taken up by divalent metal transporter 1, did not decrease SCC-⁶⁷Cu uptake. The results imply that SCC may play a significant role in copper transport and homeostasis, transferring copper particularly from the liver (but also intestinal cells) to other cells within the mammalian organism, as well as spilling excess into the urine in copper overload—as an alternative means of copper excretion.

Molecular Functions of Ceruloplasmin in Metabolic Disease Pathology

Ceruloplasmin (CP) is a multicopper oxidase and antioxidant that is mainly produced in the liver. CP not only plays a crucial role in the metabolic balance of copper and iron through its oxidase function but also exhibits antioxidant activity. In addition, CP is an acute-phase protein. In addition to being associated with aceruloplasminemia and neurodegenerative diseases such as Wilson's disease, Alzheimer's disease, and Parkinson's disease, CP also plays an important role in metabolic diseases, which are caused by metabolic disorders and vigorous metabolism, mainly including diabetes, obesity, hyperlipidemia, etc. Based on the physiological functions of CP, we provide an overview of the association of type 2 diabetes, obesity, hyperlipidemia, coronary heart disease, CP oxidative stress, inflammation, and metabolism of copper and iron. Studies have shown that metabolic diseases are closely related to systemic inflammation, oxidative stress, and disorders of copper and iron metabolism. Therefore, we conclude that CP, which can reduce the formation of free radicals in tissues, can be induced during inflammation and infection, and can correct the metabolic disorder of copper and iron, has protective and diagnostic effects on metabolic diseases.

Therapeutic role of nitroglycerin against copper-nitrilotriacetate induced hepatic and renal damage

Earlier we have shown that exposure to copper-nitrilotriacetate (Cu-NTA) manifests toxicity by generating oxidative stress and potent induction of proliferative reaction in the liver and kidney. In the study, we look at the impact of nitroglycerin (GTN) administration on Cu-NTA-induced oxidative stress and hyperproliferative response in the liver and kidney. GTN administration intraperitoneally to male Wistar rats after Cu-NTA administration intraperitoneally caused substantial protection against Cu-NTA-induced tissue injury, oxidative stress and hyperproliferative response. Cu-NTA administration at a dose of 4.5 mg/kg body weight produces significant ( p < .001) elevation in biochemical parameters including aspartate aminotransferase (AST), alanine aminotransferase (ALT), blood urea nitrogen (BUN) and creatinine (CREA) with a concomitant increase in microsomal lipid peroxidation. Along with these alterations, we discovered a substantial increment in [3H]thymidine incorporation into hepatic and renal DNA synthesis ( p < .001). Cu-NTA-induced tissue damage and lipid peroxidation in hepatic and renal tissues were inhibited by GTN treatment in a dose-dependent manner ( p < .05–0.001). Furthermore, GTN can suppress the hyperproliferative response elicited by Cu-NTA by down-regulating the rate of [3H]thymidine incorporation into hepatic and renal DNA ( p < .01–0.001). Protective effect of GTN against Cu-NTA was also confirmed by histopathological changes in liver and kidney. This result suggests that GTN may serve as a scavenger for reactive oxygen species (ROS) and reduces toxic metabolites of Cu-NTA, thereby avoiding tissue injury and oxidative stress. Further, administration of NO inhibitor, NG-Nitroarginine methyl ester (L-NAME), exacerbated Cu-NTA induced oxidative tissue damage and cell proliferation. Overall, GTN reduces Cu-NTA-induced tissue damage, oxidative stress, and proliferative response in the rat liver and kidney, according to these findings. On the basis of the above results, present study suggests that GTN may be a potential therapeutic agent for restoration of oxidative damage and proliferation to liver and kidney.

Kinetics of Cu(II) complexation by ATCUN/NTS and related peptides: a gold mine of novel ideas for copper biology

Cu(II)-peptide complexes are intensely studied as models for biological peptides and proteins and for their direct importance in copper homeostasis and dyshomeostasis in human diseases. In particular, high-affinity ATCUN/NTS (amino-terminal copper and nickel/N-terminal site) motifs present in proteins and peptides are considered as Cu(II) transport agents for copper delivery to cells. The information on the affinities and structures of such complexes derived from steady-state methods appears to be insufficient to resolve the mechanisms of copper trafficking, while kinetic studies have recently shown promise in explaining them. Stopped-flow experiments of Cu(II) complexation to ATCUN/NTS peptides revealed the presence of reaction steps with rates much slower than the diffusion limit due to the formation of novel intermediate species. Herein, the state of the field in Cu(II)-peptide kinetics is reviewed in the context of physiological data, leading to novel ideas in copper biology, together with the discussion of current methodological issues.

The molecular and cellular basis of copper dysregulation and its relationship with human pathologies

Copper (Cu) is an essential micronutrient required for the activity of redox-active enzymes involved in critical metabolic reactions, signaling pathways, and biological functions. Transporters and chaperones control Cu ion levels and bioavailability to ensure proper subcellular and systemic Cu distribution. Intensive research has focused on understanding how mammalian cells maintain Cu homeostasis, and how molecular signals coordinate Cu acquisition and storage within organs. In humans, mutations of genes that regulate Cu homeostasis or facilitate interactions with Cu ions lead to numerous pathologic conditions. Malfunctions of the Cu⁺ -transporting ATPases ATP7A and ATP7B cause Menkes disease and Wilson disease, respectively. Additionally, defects in the mitochondrial and cellular distributions and homeostasis of Cu lead to severe neurodegenerative conditions, mitochondrial myopathies, and metabolic diseases. Cu has a dual nature in carcinogenesis as a promotor of tumor growth and an inducer of redox stress in cancer cells. Cu also plays role in cancer treatment as a component of drugs and a regulator of drug sensitivity and uptake. In this review, we provide an overview of the current knowledge of Cu metabolism and transport and its relation to various human pathologies.

Copper Preserves Vasculature Structure and Function by Protecting Endothelial Cells from Apoptosis in Ischemic Myocardium

The present study was undertaken to investigate whether Cu protects vasculatures from ischemic injury in the heart. C57/B6 mice were introduced to myocardial ischemia (MI) by permanent ligation of the left anterior descending (LAD) coronary artery. Two hours post-LAD ligation, mice were intravenously injected with a Cu-albumin (Cu-alb) solution, or saline as control. At 1, 4, or 7 days post-MI, hearts were collected for further analysis. A dramatic decrease in CD31-positive endothelial cells concomitantly with abundant apoptosis, along with obstruction of blood flow, was observed in ischemic myocardium 1 day post-MI. The early Cu-alb treatment protected CD31-positive cells from apoptosis, along with a preservation of micro-vessels and a decrease in infarct size. This early vasculature preservation ensured myocardial blood perfusion and protected cardiac contractile function until 28 days post-MI. This strategy of Cu-alb treatment immediately following MI would help develop a therapeutic approach for acute heart attack patients in a clinical setting.

"Metal elements and pesticides as risk factors for Parkinson's disease - A review"

Essential metals including iron (Fe) and manganese (Mn) with known physiological functions in human body play an important role in cell homeostasis. Excessive exposure to these essential as well as non-essential metals including mercury (Hg) and Aluminum (Al) may contribute to pathological conditions, including PD. Each metal could be toxic through specific pathways. Epidemiological evidences from occupational and ecological studies besides various in vivo and in vitro studies have revealed the possible pathogenic role and neurotoxicity of different metals. Pesticides are substances that aim to mitigate the harm done by pests to plants and crops, and are extensively used to boost agricultural production. This review provides an outline of our current knowledge on the possible association between metals and PD. We have discussed the potential association between these two, furthermore the chemical properties, biological and toxicological aspects as well as possible mechanisms of Fe, Mn, Cu, Zn, Al, Ca, Pb, Hg and Zn in PD pathogenesis. In addition, we review recent evidence on deregulated microRNAs upon pesticide exposure and possible role of deregulated miRNA and pesticides to PD pathogenesis.

Dextran-modified Quercetin-Cu(II)/hyaluronic acid nanomedicine with natural poly(ADP-ribose) polymerase inhibitor and dual targeting for programmed synthetic lethal therapy in triple-negative breast cancer

Serious side effects from chemotherapies are the main problem with cancer treatments. To solve these issues, precision cancer nanomedicine based on natural therapeutic materials is developed, which enables specifically apoptosis by interacting with genetic mutation in cancer cells, while leaving normal cells unaffected. Here, we report a novel nanomedicine (CuQDA/IO@HA) composed of hyaluronic acid (HA) / copper ion (Cu(II))-chelated dextran-aldehyde (DA)-quercetin (Q) with dual targeting for synthetic lethal therapy. The CuQDA/IO@HA prepared using a ratio of metal/Q at 0.5:1 resulted in a stable particle structure with uniform particle distribution. The CuQDA/IO@HA can specifically target and induce specific cytotoxicity in BRCA-mutant cancer cells in vitro. Combination treatment with CuQDA/IO@HA and magnetic navigation can induce poly (ADP-ribose) polymerase (PARP) inhibition and DNA damage in BRCA-mutant triple-negative breast cancer (TNBC) via CD44 targeting. The dual-targeting CuQDA/IO@HA can extend the median survival of the BRCA-mutant xenograft mice from 34 to 61 days in comparison to Q treatment alone in vivo, which is attributed to the significant increase in γH2AX, leading to significant apoptosis. More importantly, the CuQDA/IO@HA displayed biocompatibility and no obvious side-effect in normal organs. These results demonstrate the promising potential of integrating natural and metal ions into a nanomedicine that can provide precision medicine through synthetic lethality.

Size-Dependent Bioactivity of Silver Nanoparticles: Antibacterial Properties, Influence on Copper Status in Mice, and Whole-Body Turnover

Purpose

The ability of silver nanoparticles (AgNPs) of different sizes to influence copper metabolism in mice is assessed.

Materials and Methods

AgNPs with diameters of 10, 20, and 75 nm were fabricated through a chemical reduction of silver nitrate and characterized by UV/Vis spectrometry, transmission and scanning electronic microscopy, and laser diffractometry. To test their bioactivity, Escherichia coli cells, cultured A549 cells, and C57Bl/6 mice were used. The antibacterial activity of AgNPs was determined by inhibition of colony-forming ability, and cytotoxicity was tested using the MTT test (viability, %). Ceruloplasmin (Cp, the major mammalian extracellular copper-containing protein) concentration and enzymatic activity were measured using gel-assay analyses and WB, respectively. In vitro binding of AgNPs with serum proteins was monitored with UV/Vis spectroscopy. Metal concentrations were measured using atomic absorption spectrometry.

Results

The smallest AgNPs displayed the largest dose- and time-dependent antibacterial activity. All nanoparticles inhibited the metabolic activity of A549 cells in accordance with dose and time, but no correlation between cytotoxicity and nanoparticle size was found. Nanosilver was not uniformly distributed through the body of mice intraperitoneally treated with low AgNP concentrations. It was predominantly accumulated in liver. There, nanosilver was included in ceruloplasmin, and Ag-ceruloplasmin with low oxidase activity level was formed. Larger nanoparticles more effectively interfered with the copper metabolism of mice. Large AgNPs quickly induced a drop of blood serum oxidase activity to practically zero, but after cancellation of AgNP treatment, the activity was rapidly restored. A major fraction of the nanosilver was excreted in the bile with Cp. Nanosilver was bound by alpha-2-macroglobulin in vitro and in vivo, but silver did not substitute for the copper atoms of Cp in vitro.

Conclusion

The data showed that even at low concentrations, AgNPs influence murine copper metabolism in size-dependent manner. This property negatively correlated with the antibacterial activity of AgNPs.

PBT2 acts through a different mechanism of action than other 8-hydroxyquinolines: an X-ray fluorescence imaging study

8-Hydroxyquinolines (8HQs) comprise a family of metal-binding compounds that have been used or tested for use in numerous medicinal applications, including as treatments for bacterial infection, Alzheimer's disease, and cancer. Two key 8HQs, CQ (5-chloro-7-iodo-8-hydroxyquinoline) and PBT2 (2-(dimethylamino)methyl-5,7-dichloro-8-hydroxyquinoline), have drawn considerable interest and have been the focus of many studies investigating their in vivo properties. These drugs have been described as copper and zinc ionophores because they do not cause metal depletion, as would be expected for a chelation mechanism, but rather cellular accumulation of these ions. In studies of their anti-cancer properties, CQ has been proposed to elicit toxic intracellular copper accumulation and to trigger apoptotic cancer cell death through several possible pathways. In this study we used synchrotron X-ray fluorescence imaging, in combination with biochemical assays and light microscopy, to investigate 8HQ-induced alterations to metal ion homeostasis, as well as cytotoxicity and cell death. We used the bromine fluorescence from a bromine labelled CQ congener (5,7-dibromo-8-hydroxyquinoline; B2Q) to trace the intracellular localization of B2Q following treatment and found that B2Q crosses the cell membrane. We also found that 8HQ co-treatment with Cu(ii) results in significantly increased intracellular copper and significant cytotoxicity compared with 8HQ treatments alone. PBT2 was found to be more cytotoxic, but a weaker Cu(ii) ionophore than other 8HQs. Moreover, treatment of cells with copper in the presence of CQ or B2Q resulted in copper accumulation in the nuclei, while PBT2-guided copper was distributed near to the cell membrane. These results suggest that PBT2 may be acting through a different mechanism than that of other 8HQs to cause the observed cytotoxicity.

Copper Dyshomeostasis in Neurodegenerative Diseases-Therapeutic Implications

Copper is one of the most abundant basic transition metals in the human body. It takes part in oxygen metabolism, collagen synthesis, and skin pigmentation, maintaining the integrity of blood vessels, as well as in iron homeostasis, antioxidant defense, and neurotransmitter synthesis. It may also be involved in cell signaling and may participate in modulation of membrane receptor-ligand interactions, control of kinase and related phosphatase functions, as well as many cellular pathways. Its role is also important in controlling gene expression in the nucleus. In the nervous system in particular, copper is involved in myelination, and by modulating synaptic activity as well as excitotoxic cell death and signaling cascades induced by neurotrophic factors, copper is important for various neuronal functions. Current data suggest that both excess copper levels and copper deficiency can be harmful, and careful homeostatic control is important. This knowledge opens up an important new area for potential therapeutic interventions based on copper supplementation or removal in neurodegenerative diseases including Wilson’s disease (WD), Menkes disease (MD), Alzheimer’s disease (AD), Parkinson’s disease (PD), and others. However, much remains to be discovered, in particular, how to regulate copper homeostasis to prevent neurodegeneration, when to chelate copper, and when to supplement it.

L-Cysteine-mediated modulation of copper trafficking in prostate cancer cells: an in vitro and in vivo investigation with 64Cu and 64Cu-PET

Copper imbalance is implicated in many diseases, including cancer. Copper in blood is mainly transported by carrier proteins but a small fraction is bound to low molecular weight species, possibly amino acids. Their roles in cellular copper delivery are unknown. Our aim was to test whether accumulation of 64Cu into cancer-derived cells can be influenced by copper-binding serum amino acids. In vitro cellular accumulation of 64Cu was measured in Hank's Balanced Salt Solution in the presence of 100 μM l-histidine, l-methionine, l-cysteine and l-threonine. l-Cysteine markedly increased 64Cu accumulation and retention in DU145, PC3 and SK-OV-3 cells, while some other cell lines did not show an effect. This effect was not due to 64Cu delivery in the form of a 64Cu-cysteine complex, nor to reduction of 64Cu(ii) to 64Cu(i) by l-cysteine. Pre-incubation of cells with l-cysteine increased 64Cu accumulation, even if l-cysteine was removed from HBSS before 64Cu was added. The effect of l-cysteine on 64Cu accumulation was not mediated by increased glutathione synthesis. Despite the demonstrable in vitro effect, pre-injection of l-cysteine precursor N-acetyl-cysteine (NAC) in vivo did not enhance 64Cu delivery to DU145 xenografts in mice. Instead, it decreased 64Cu accumulation in the DU145 tumour and in brain, as assessed by PET imaging. We conclude that 64Cu is not delivered to DU145 cancer cells in vitro as a complex with amino acids but its cellular accumulation is enhanced by l-cysteine or NAC influx to cells. The latter effect was not demonstrable in vivo in the DU145 xenograft.

Copper Homeostasis in Mammals, with Emphasis on Secretion and Excretion. A Review

One of the hallmarks of Cu metabolism in mammals is that tissue and fluid levels are normally maintained within a very narrow range of concentrations. This results from the ability of the organism to respond to variations in intake from food and drink by balancing excretion, which occurs mainly via the bile and feces. Although this sounds straightforward and we have already learned a great deal about aspects of this process, the balance between overall intake and excretion occurs over a high background of Cu recycling, which has generally been ignored. In fact, most of the Cu absorbed from the GI tract actually comes from digestive fluids and is constantly “re-used”. A great deal more recycling of Cu probably occurs in the interior, between cells of individual tissues and the fluid of the blood and interstitium. This review presents what is known that is pertinent to understanding these complexities of mammalian Cu homeostasis and indicates where further studies are needed.

Copper Complexes with 1,10-Phenanthroline Derivatives: Underlying Factors Affecting Their Cytotoxicity

The interpretation of in vitro cytotoxicity data of Cu(II)-1,10-phenanthroline (phen) complexes normally does not take into account the speciation that complexes undergo in cell incubation media and its implications in cellular uptake and mechanisms of action. We synthesize and test the activity of several distinct Cu(II)-phen compounds; up to 24 h of incubation, the cytotoxic activity differs for the Cu complexes and the corresponding free ligands, but for longer incubation times (e.g., 72 h), all compounds display similar activity. Combining the use of several spectroscopic, spectrometric, and electrochemical techniques, the speciation of Cu-phen compounds in cell incubation media is evaluated, indicating that the originally added complex almost totally decomposed and that Cu(II) and phen are mainly bound to bovine serum albumin. Several methods are used to disclose relationships between structure, activity, speciation in incubation media, cellular uptake, distribution of Cu in cells, and cytotoxicity. Contrary to what is reported in most studies, we conclude that interaction with cell components and cell death involves the separate action of Cu ions and phen molecules, not [Cu(phen)_n] species. This conclusion should similarly apply to many other Cu-ligand systems reported to date.

Effects of Organic Copper on Growth Performance and Oxidative Stress in Mice

Copper (Cu) has been used as a feed additive for many years. However, high Cu amounts can cause oxidative stress and adversely affect animal performance. Such negative effects may depend on the amounts and forms of Cu. In the present study, the effects of inorganic Cu (CuSO₄) and organic Cu (chelate-Cu) present in mice feed on daily growth rate and Cu deposition in the liver, kidneys, spleen, brain, and serum were assessed in addition to the oxidative stress levels in the liver and brain. Organic Cu at a concentration of 15 mg/kg significantly enhanced daily growth rate in mice, whereas Cu deposition in the livers was significantly lower than that in the inorganic Cu group. Glutathione peroxidase activity in the liver of the mice fed with organic Cu significantly improved, whereas malondialdehyde levels in the brain and liver were significantly lower than that in the inorganic Cu group. The different effects of organic Cu and inorganic Cu provide key evidence supporting the use of organic Cu in animal feeds.

Copper(II)-binding equilibria in human blood

It has been reported that Cu(II) ions in human blood are bound mainly to serum albumin (HSA), ceruloplasmin (CP), alpha-2-macroglobulin (α2M) and His, however, data for α2M are very limited and the thermodynamics and kinetics of the copper distribution are not known. We have applied a new LC-ICP MS-based approach for direct determination of Cu(II)-binding affinities of HSA, CP and α2M in the presence of competing Cu(II)-binding reference ligands including His. The ligands affected both the rate of metal release from Cu•HSA complex and the value of K_D. Slow release and K_D = 0.90 pM was observed with nitrilotriacetic acid (NTA), whereas His showed fast release and substantially lower K_D = 34.7 fM (50 mM HEPES, 50 mM NaCl, pH 7.4), which was explained with formation of ternary His•Cu•HSA complex. High mM concentrations of EDTA were not able to elicit metal release from metallated CP at pH 7.4 and therefore it was impossible to determine the K_D value for CP. In contrast to earlier inconclusive evidence, we show that α2M does not bind Cu(II) ions. In the human blood serum ~75% of Cu(II) ions are in a nonexchangeable manner bound to CP and the rest exchangeable copper is in an equilibrium between HSA (~25%) and Cu(II)-His-Xaa ternary complexes (~0.2%).

Interplays between copper and Mycobacterium tuberculosis GroEL1

The chaperone GroEL1 enhances copper tolerance during Mycobacterium bovis BCG biofilm formation. The binding of copper ions to the GroEL1 histidine-rich region protects the chaperone from destabilization and increases its ATPase activity.

Does Ceruloplasmin Defend Against Neurodegenerative Diseases?

Ceruloplasmin (CP) is the major copper transport protein in plasma, mainly produced by the liver. Glyco-sylphosphatidylinositol-linked CP (GPI-CP) is the predominant form expressed in astrocytes of the brain. A growing body of evidence has demonstrated that CP is an essential protein in the body with multiple functions such as regulating the home-ostasis of copper and iron ions, ferroxidase activity, oxidizing organic amines, and preventing the formation of free radicals. In addition, as an acute-phase protein, CP is induced during inflammation and infection. The fact that patients with genetic disorder aceruloplasminemia do not suffer from tissue copper deficiency, but rather from disruptions in iron metabolism shows essential roles of CP in iron metabolism rather than copper. Furthermore, abnormal metabolism of metal ions and ox-idative stress are found in other neurodegenerative diseases, such as Wilson’s disease, Alzheimer’s disease and Parkinson’s disease. Brain iron accumulation and decreased activity of CP have been shown to be associated with neurodegeneration. We hypothesize that CP may play a protective role in neurodegenerative diseases. However, whether iron accumulation is a cause or a result of neurodegeneration remains unclear. Further research on molecular mechanisms is required before a con-sensus can be reached regarding a neuroprotective role for CP in neurodegeneration. This review article summarizes the main physiological functions of CP and the current knowledge of its role in neurodegenerative diseases.

Serum and brain natural copper stable isotopes in a mouse model of Alzheimer's disease

Alzheimer’s disease is associated with the production of Cu rich aβ fibrils. Because monitoring the changes in Cu level of organs has been proposed to follow the evolution of the disease, we analyzed the copper isotopic composition of serum and brain of APPswe/PSEN1dE9 transgenic mice, a model of Alzheimer’s disease, and wild-type (WT) controls. Serum composition of 3, 6, 9 and 12-month-old mice, as well as the composition of 9 brains of 12-month-old mice are reported. In WT mice, brains were ~1‰ isotopically heavier than serum, and the Cu isotopic composition of the serum was isotopically different between males and females. We propose that this effect of sex on the Cu isotopic budget of the serum may be related to a difference of Cu speciation and relative abundance of Cu carriers. Brains of APPswe/PSEN1dE9 mice were slightly lighter than brains of WT mice, while not statistically significant. This trend may reflect an increase of Cu(I) associated with the formation of Aβ fibrils. The Cu isotopic composition of the brains and serum were correlated, implying copper transport between these two reservoirs, in particular a transfer of Cu(I) from the brain to the serum. Altogether, these data suggest that Cu stable isotopic composition of body fluid may have the potential to be used as detection tools for the formation of Aβ fibrils in the brain, but further work has to be done.

Copper Metabolism of Newborns Is Adapted to Milk Ceruloplasmin as a Nutritive Source of Copper: Overview of the Current Data

Copper, which can potentially be a highly toxic agent, is an essential nutrient due to its role as a cofactor for cuproenzymes and its participation in signaling pathways. In mammals, the liver is a central organ that controls copper turnover throughout the body, including copper absorption, distribution, and excretion. In ontogenesis, there are two types of copper metabolism, embryonic and adult, which maintain the balance of copper in each of these periods of life, respectively. In the liver cells, these types of metabolism are characterized by the specific expression patterns and activity levels of the genes encoding ceruloplasmin, which is the main extracellular ferroxidase and copper transporter, and the proteins mediating ceruloplasmin metalation. In newborns, the molecular genetic mechanisms responsible for copper homeostasis and the ontogenetic switch from embryonic to adult copper metabolism are highly adapted to milk ceruloplasmin as a dietary source of copper. In the mammary gland cells, the level of ceruloplasmin gene expression and the alternative splicing of its pre-mRNA govern the amount of ceruloplasmin in the milk, and thus, the amount of copper absorbed by a newborn is controlled. In newborns, the absorption, distribution, and accumulation of copper are adapted to milk ceruloplasmin. If newborns are not breast-fed in the early stages of postnatal development, they do not have this natural control ensuring alimentary copper balance in the body. Although there is still much to be learned about the neonatal consequences of having an imbalance of copper in the mother/newborn system, the time to pay attention to this problem has arrived because the neonatal misbalance of copper may provoke the development of copper-related disorders.

Absorption Mechanisms of Iron, Copper, and Zinc: An Overview

Essential trace elements play pivotal roles in numerous structural and catalytic functions of proteins. Adequate intake of essential trace elements from the daily diet is indispensable to the maintenance of health, and their deficiency leads to a variety of conditions. However, excessive amounts of these trace elements may be highly toxic, and in some cases, may cause damage by the production of harmful reactive oxygen species. Homeostatic dysregulation of their metabolism increases the risk of developing diseases. Specific transport proteins that facilitate influx or efflux of trace elements play key roles in maintaining the homeostasis. Recent elucidation of their crucial functions significantly facilitated our understanding of the molecular mechanisms of iron (Fe), copper (Cu), and zinc (Zn) absorption in the small intestine. This paper summarizes their absorption mechanisms, with a focus on indispensable functions of the molecules involved in it, and briefly discusses the mechanisms of homeostatic control of each element at the cellular and systemic levels.

Engineered nanomaterials and oxidative stress: current understanding and future challenges

Engineered nanomaterials (ENMs) are being incorporated at an unprecedented rate into consumer and biomedical products. This increased usage will ultimately lead to increased human exposure; therefore, understanding ENM safety is an important concern to the public. Although ENMs may exert toxicity through multiple mechanisms, one common mechanism of toxicity recognized across a range of ENMs with varying physicochemical properties is oxidative stress. Further, it is recognized that several key physicochemical properties of ENMs including size, material composition, surface chemistry, band gap, and level of ionic dissolution for example contribute to ENM driven oxidative stress. While it has been shown that exposure of cells to ENMs at high acute doses produce reactive oxygen species at a toxic level often leading to cytotoxicity, there is little research looking at oxidative stress caused by ENM exposure at more relevant low or non-toxic doses. Although the former can lead to apoptosis, genotoxicity, and inflammation, the latter can potentially be damaging as chronic changes to the intracellular redox state leads to cellular reprogramming, resulting in disease initiation and progression among other systemic damage. This current opinions article will review the physicochemical properties and mechanisms associated with ENM-driven oxidative stress and will discuss the need for research investigating effects on the redox proteome that may lead to cellular dysfunction at low or chronic doses of ENMs.

An endoplasmic reticulum-selective ratiometric fluorescent probe for imaging a copper pool

Hydrazide-linked naphthalimides undergo copper ion-selective hydrolysis with concomitant ratiometric fluorescence change. In addition, probe 1 is biocompatible and mainly localized to the endoplasmic reticulum (ER) in live HeLa cells. It thus can be used for imaging copper accumulation in the ER of live cells, as implied in copper-overloaded situations.

Ceruloplasmin gene expression profile changes in the rat mammary gland during pregnancy, lactation and involution

Copper metabolism disturbances in mammary gland (MG) cells have severe consequences in newborns. The mechanism that controls the balance of copper in the MG has not been thoroughly characterized. Four primary copper homeostasis genes in mammals: (1) ceruloplasmin (Cp) encoding multifunction multicopper blue (ferr)oxidase; (2) CTR1 encoding high affinity copper importer 1; and (3 and 4) two similar genes encoding Cu(I)/Cu(II)-ATPases P1 type (ATP7A and ATP7B) responsible for copper efflux from the cells and metallation of cuproenzymes formed in the Golgi complex are expressed in MG. This study aimed to characterize expression of these genes during pregnancy, lactation and forced involution in the rat MG. We found that Cp anchored to the plasma membrane and ATP7A were expressed during pregnancy and lactation. Soluble Cp and ATP7B were highly expressed in lactating MG decreasing to its ending. CTR1 activity increased during MG growth and reached its maximum at postpartum and then it decreased until the end of lactation. During early forced MG involution, Cp gene expression persisted; while a form of Cp that lacked exon 18 appeared. We suggest that Cp gene expressional changes at the transcriptional and posttranscriptional level reflect various physiological functions of Cp proteins during MG remodeling.

Neurotoxicity of Copper

Copper is an essential trace metal that is required for several important biological processes, however, an excess of copper can be toxic to cells. Therefore, systemic and cellular copper homeostasis is tightly regulated, but dysregulation of copper homeostasis may occur in disease states, resulting either in copper deficiency or copper overload and toxicity. This chapter will give an overview on the biological roles of copper and of the mechanisms involved in copper uptake, storage, and distribution. In addition, we will describe potential mechanisms of the cellular toxicity of copper and copper oxide nanoparticles. Finally, we will summarize the current knowledge on the connection of copper toxicity with neurodegenerative diseases.

In Vitro and In Vivo Effectiveness of an Innovative Silver-Copper Nanoparticle Coating of Catheters To Prevent Methicillin-Resistant Staphylococcus aureus Infection

In this study, silver/copper (Ag/Cu)-coated catheters were investigated for their efficacy in preventing methicillin-resistant Staphylococcus aureus (MRSA) infection in vitro and in vivo Ag and Cu were sputtered (67/33% atomic ratio) on polyurethane catheters by direct-current magnetron sputtering. In vitro, Ag/Cu-coated and uncoated catheters were immersed in phosphate-buffered saline (PBS) or rat plasma and exposed to MRSA ATCC 43300 at 10(4) to 10(8) CFU/ml. In vivo, Ag/Cu-coated and uncoated catheters were placed in the jugular vein of rats. Directly after, MRSA (10(7) CFU/ml) was inoculated in the tail vein. Catheters were removed 48 h later and cultured. In vitro, Ag/Cu-coated catheters preincubated in PBS and exposed to 10(4) to 10(7) CFU/ml prevented the adherence of MRSA (0 to 12% colonization) compared to uncoated catheters (50 to 100% colonization; P < 0.005) and Ag/Cu-coated catheters retained their activity (0 to 20% colonization) when preincubated in rat plasma, whereas colonization of uncoated catheters increased (83 to 100%; P < 0.005). Ag/Cu-coating protection diminished with 10(8) CFU/ml in both PBS and plasma (50 to 100% colonization). In vivo, Ag/Cu-coated catheters reduced the incidence of catheter infection compared to uncoated catheters (57% versus 79%, respectively; P = 0.16) and bacteremia (31% versus 68%, respectively; P < 0.05). Scanning electron microscopy of explanted catheters suggests that the suboptimal activity of Ag/Cu catheters in vivo was due to the formation of a dense fibrin sheath over their surface. Ag/Cu-coated catheters thus may be able to prevent MRSA infections. Their activity might be improved by limiting plasma protein adsorption on their surfaces.

Ceruloplasmin and other copper binding components of blood plasma and their functions: an update

We know that blood plasma contains many proteins and also other components that bind copper. The largest contributor to copper in the plasma is ceruloplasmin, which accounts for 40-70 percent. Apart from ceruloplasmin and albumin, most of these components have not been studied extensively, and even for ceruloplasmin and albumin, much remains to be discovered. New components with new functions, and new functions of known components are emerging, some warranting reconsideration of earlier findings. The author's laboratory has been actively involved in research on this topic. This review summarizes and updates our knowledge of the nature and functions of ceruloplasmin and the other known and emerging copper-containing molecules (principally proteins) in this fluid, to better understand how they contribute to copper homeostasis and consider their potential significance to health and disease.