Copper Transport Research Articles

Bioactive copper(II) agents and their potential involvement in the treatment of copper deficiency-related orphan diseases

The deregulation of copper homoeostasis can promote various diseases such as Menkes disease or hypertrophic cardioencephalomyopathy. We have recently synthesized solid copper(II) complexes ([Cu(His)2Cl2] and [Cu(Ser)2]), stable in physiological media and with potential as therapeutic agents. This report describes: i) the biocompatibility of these complexes at concentrations up to 100 μM using a differentiated Caco-2 cells model; ii) their transport across the intestinal epithelium using a transepithelial resistance assay and monitoring the amount of copper complexes at the apical and basolateral sides of the cells. The results suggest that the flow occurs through paracellular routes. The intracellular copper retention was <2.7% with no significant differences in intracellular copper content between 6 h and 48 h, suggesting an early copper retention process. Furthermore, this is the first evidence that demonstrates [Cu(His)2Cl2] and [Cu(Ser)2] induce transcriptional downregulation of the four major copper transporters (CTR1, DMT1, ATP7A, ATP7B), and the upregulation of the metallothionein gene expression. A remarkable finding was the increase in cytochrome c oxidase activity observed after the treatment of differentiated Caco-2 cells with copper(II) complexes at concentrations of 50–100 μM. The understanding of the transport mechanisms of these copper(II) complexes across the intestinal epithelium and of their subsequent biological activities could contribute to the development of optimal pharmaceutical formulations for the therapy of copper deficiency-related diseases.

Copper metabolism and hepatocellular carcinoma: current insights.

Copper is an essential trace element that acts as a cofactor in various enzyme active sites in the human body. It participates in numerous life activities, including lipid metabolism, energy metabolism, and neurotransmitter synthesis. The proposal of "Cuproptosis" has made copper metabolism-related pathways a research hotspot in the field of tumor therapy, which has attracted great attention. This review discusses the biological processes of copper uptake, transport, and storage in human cells. It highlights the mechanisms by which copper metabolism affects hepatocellular carcinogenesis and metastasis, including autophagy, apoptosis, vascular invasion, cuproptosis, and ferroptosis. Additionally, it summarizes the current clinical applications of copper metabolism-related drugs in antitumor therapy.

The 100 top-cited articles in the field of Wilson’s disease from 1990 to 2022: A bibliometric study

ObjectivesTo characterize the 100 most-cited articles in the field of Wilson’s Disease (WD) to provide a general overview and reveal the historical developments classical studies, and new findings. DesignWD-related articles were searched on the Web of Science database. The 100 most-cited articles were retrieved and their descriptive statistics were analyzed. Data extraction and synthesisThe 100 most-cited articles in the field of WD were selected and several parameters, including citation count, citation density, first author, corresponding author, journal, country, institution, and keywords were extracted to assess the overall quality and impact of the articles. ResultsMost of the selected 100 articles were published in the 1990s and 2000s, with the highest number of articles published in 2005. Citations per paper ranged from 100 to 1,631, with a mean number of citations of 199.03. The top 100 articles were published in 38 journals, and the majority were published in the Journal of Biological Chemistry. The most prominent research themes were clinical presentations, clinical trials, copper transport mechanisms, and dysregulation of copper metabolism. Prof. Svetlana Lutsenko, Prof. Peter Ferenci, Prof. George J. Brewer, and Prof. Diane W. Cox were among the most influential researchers in this field, while Euro-American countries were the most dominant in terms of research output. Keywords network analysis identified "Transporting ATPase," "ATP7B," and “Menkes disease” as the most influential keywords. Moreover, disease management, WD clinical phenotype, ATP7B function, and copper metabolism are potential hotspots in future WD research. ConclusionsThis study reveals the most influential articles in the field of WD research. In addition, the major research themes and technological innovations in the field of WD worldwide are presented.

Nicotianamine: A Key Player in Metal Homeostasis and Hyperaccumulation in Plants

Nicotianamine (NA) is a low-molecular-weight N-containing metal-binding ligand, whose accumulation in plant organs changes under metal deficiency or excess. Although NA biosynthesis can be induced in vivo by various metals, this non-proteinogenic amino acid is mainly involved in the detoxification and transport of iron, zinc, nickel, copper and manganese. This review summarizes the current knowledge on NA biosynthesis and its regulation, considers the mechanisms of NA secretion by plant roots, as well as the mechanisms of intracellular transport of NA and its complexes with metals, and its role in radial and long-distance metal transport. Its role in metal tolerance is also discussed. The NA contents in excluders, storing metals primarily in roots, and in hyperaccumulators, accumulating metals mainly in shoots, are compared. The available data suggest that NA plays an important role in maintaining metal homeostasis and hyperaccumulation mechanisms. The study of metal-binding compounds is of interdisciplinary significance, not only regarding their effects on metal toxicity in plants, but also in connection with the development of biofortification approaches to increase the metal contents, primarily of iron and zinc, in agricultural plants, since the deficiency of these elements in food crops seriously affects human health.

Copper transporter protein (MctB) as a therapeutic target to elicit antimycobacterial activity against tuberculosis

Tuberculosis (TB) is a prehistoric infection and major etiologic agent of TB, Mycobacterium tuberculosis, which is considered to have advanced from an early progenitor species found in Eastern Africa. By the 1800s, there were approximately 800 to 1000 fatality case reports per 100,000 people in Europe and North America. This research suggests an In-silico study to identify potential inhibitory compounds for the target Mycobacterial copper transport protein (Mctb). ADME-based virtual screening, molecular docking, and molecular dynamics simulations were conducted to find promising compounds to modulate the function of the target protein. Four chemical compounds, namely Anti-MCT1, Anti-MCT2, Anti-MCT3 and Anti-MCT4 out of 1500 small molecules from the Diverse-lib of MTiOpenScreen were observed to completely satisfy Lipinski rule of five and Veber’s rule. Further, significantly steady interactions with the MctB target protein were observed. Docking experiments have presented 9 compounds with less than −9.0 kcal/mol free binding energies and further MD simulation eventually gave 4 compounds having potential interactions and affinity with target protein and favorable binding energy ranging from −9.2 to −9.3 kcal/mol. We may propose these compounds as an effective candidate to reduce the growth of M. tuberculosis and may also assist present a novel therapeutic approach for Tuberculosis. In vivo and In vitro validation would be needed to proceed further in this direction. Communicated by Ramaswamy H. Sarma

Copper deprivation enhances the chemosensitivity of pancreatic cancer to rapamycin by mTORC1/2 inhibition

Cuproplasia, or copper-dependent cell proliferation, has been observed in varieties of solid tumors along with aberrant copper homeostasis. Several studies reported good response of patients to copper chelator assisted neoadjuvant chemotherapy, however, the internal target molecules are still undetermined. Unravel copper-associated tumor signaling would be valuable to forge new links to translate biology of copper into clinical cancer therapies. We evaluated the significance of high-affinity copper transporter-1 (CTR1) by bioinformatic analysis, and in 19 pairs of clinical specimens. Then, with the help of gene interference and chelating agent, enriched signaling pathways were identified by KEGG analysis and immunoblotting. Accompanying biological capability of pancreatic carcinoma-associated proliferation, cell cycle, apoptosis, and angiogenesis were investigated. Furthermore, a combination of mTOR inhibitor and CTR1 suppressor has been assessed in xenografted tumor mouse models. Hyperactive CTR1 was investigated in pancreatic cancer tissues and proven to as the key point of cancer copper homeostasis. Intracellular copper deprivation induced by CTR1 gene knock-down or systematic copper chelation by tetrathiomolybdate suppressed proliferation and angiogenesis of pancreatic cancer cell. PI3K/AKT/mTOR signaling pathway was suppressed by inhibiting the activation of p70(S6)K and p-AKT, and finally inhibited mTORC1 and mTORC2 after copper deprivation. Additionally, CTR1 gene silencing successfully improved the anti-cancer effect of mTOR inhibitor rapamycin. Our study reveals that CTR1 contributes to pancreatic tumorigenesis and progression, by up-regulating the phosphorylation of AKT/mTOR signaling molecules. Recovering copper balance by copper deprivation addresses as promising strategy for improved cancer chemotherapy.

Matrigel-based organoid culture of malignant mesothelioma reproduces cisplatin sensitivity through CTR1

Organoids are a three-dimensional (3D) culture system that simulate actual organs. Therefore, tumor organoids are expected to predict precise response to chemotherapy in patients. However, to date, few studies have studied the drug responses in organoids of malignant mesothelioma (MM). The poor prognosis of MM emphasizes the importance of establishing a protocol for generating MM-organoid for research and clinical use. Here, we established murine MM organoids from p53+/-or wild-type C57BL/6 strain by intraperitoneal injection either with crocidolite or carbon nanotube. Established MM-organoids proliferated in Matrigel as spheroids. Subcutaneous injection assays revealed that the MM-organoids mimicked actual tissue architecture and maintained the original histological features of the primary MM. RNA sequencing and pathway analyses revealed that the significant expressional differences between the 2D- and 3D-culture systems were observed in receptor tyrosine kinases, including IGF1R and EGFR, glycosylation and cholesterol/steroid metabolism. MM-organoids exhibited a more sensitive response to cisplatin through stable plasma membrane localization of a major cisplatin transporter, copper transporter 1/Slc31A1 (Ctr1) in comparison to 2D-cultures, presumably through glycosylation and lipidation. The Matrigel culture system facilitated the localization of CTR1 on the plasma membrane, which simulated the original MMs and the subcutaneous xenografts. These results suggest that the newly developed protocol for MM-organoids is useful to study strategies to overcome chemotherapy resistance to cisplatin.

Environment, subsistence strategies and settlement seasonality in the Negev Highlands (Israel) during the Bronze and Iron Ages: The palynological evidence.

The Negev Highlands arid region (southern Levant) shows evidence of sharp settlement fluctuations, with several periods of strong human activity separated by centuries with no evidence of sedentary life. In this study, we used the palynological method in order to shed light on the region's demographic history in the Bronze and Iron Ages. Fifty-four samples of pollen were collected and analyzed from secure archaeological contexts in four Negev Highlands sites: Nahal Boqer 66, dated to the Early Bronze Age and Early Intermediate Bronze Age (ca. 3200-2200 BCE); Ein Ziq, dated to the Early Intermediate Bronze Age (ca. 2500-2200 BCE); Mashabe Sade, dated to the Intermediate Bronze Age (ca. 2500-2000 BCE); and Haroa, dated to the Iron Age IIA (ca. late 10th through 9th centuries BCE). Our study revealed no evidence of cereal cultivation, with some hints that the inhabitants' diets may have included plants gathered from the wild. Only one of the sites, Nahal Boqer 66, showed micro-indicators of animal dung remains, suggesting that the inhabitants herded animals. The palynological evidence did, however, emphasize that the livestock there were not fed or supplemented with agricultural by-products but rather grazed freely on wild vegetation. The pollen data also suggest that all four sites were occupied only during late winter and spring. The activity in the Negev Highlands during the third millennium BCE was probably related to the copper industry in the Arabah and to copper transportation to settled neighboring lands, especially Egypt. A relatively humid climate supported the trade through the Negev Highlands. Deterioration in both climate conditions and settlement activity was documented in the second half of the Intermediate Bronze Age.

A ceRNA network-mediated over-expression of cuproptosis-related gene SLC31A1 correlates with poor prognosis and positive immune infiltration in breast cancer.

Solute carrier family 31 member 1(SLC31A1) has been reported as the copper importer, and was identified to be involved in the process of "cuproptosis". However, the mechanism of SLC31A1 in breast cancer remains unclear. We examined the expression of SLC31A1 mRNA in breast cancer tissues and cell lines using Real-time PCR. The data for this study were obtained from The Cancer Genome Atlas (TCGA) database and analyzed via R 3.6.3. TIMER, UALCAN, GEPIA2, STRING, Metascape, Kaplan-Meier Plotter, starBase and miRNet websites were used for a comprehensive analysis of SLC31A1. Our study suggested that SLC31A1 mRNA was over-expressed in breast tumor tissue and breast cancer cell lines, and which was closely related to poor relapse-free survival (RFS) and distant metastasis-free survival (DMFS). In addition, we constructed a co-expression network of SLC31A1. Functional enrichment analysis indicated that they were mainly involved in copper ion transport. Interestingly, SLC31A1 expression was positively associated with all m6A-related genes, especially with YTHDF3 (r = 0.479). Importantly, the LINC00511/miR-29c-3p/SLC31A1 axis was identified as the most potential pathway promoting breast cancer progress by affecting copper transport. Furthermore, the expression level of SLC31A1 in breast cancer was positively correlated with tumor immune cell infiltration, immune cell biomarkers and cancer-associated fibroblast (CAF). Up-regulation of SLC31A1 expression and regulation of copper ion transport mediated by LINC00511-miR-29-3p axis is related to poor prognosis and positively correlated with tumor immune infiltration in breast cancer.

Transcriptional profiles in zebrafish atp7a mutants and responses of atp7a mutants to Cu stress

As a copper (Cu) transport ATPase, ATP7A plays an important role in maintaining Cu homeostasis in the body, but the developmental and physiological roles of atp7a in zebrafish embryogenesis are rarely studied. In this study, normal morphological phenotypes of atp7a−/− homozygous zebrafish were observed at both embryonic and adult stages, however, atp7a−/− larvae exhibited delayed touch response and obvious transcriptome changes. Compared with the WT (wild type), differentially expressed genes (DEGs) in atp7a−/− larvae showed the enrichment in gene ontology (GO) terms related to several processes including ATPase activity, oxidoreductase activity, active transmembrane transporter activity, ion binding, and the citrate cycle. Furthermore, decreases in both ATP content and Na+/K+-ATPase activity in atp7a−/− embryos and larvae were unveiled. 57 overlapping DEGs were found both in WT stressed with Cu and in WT mutated with atp7a, and GO term analysis indicated the enrichment in the genes related to neurexin family protein binding and neuronal cell-cell adhesion. Moreover, 42 overlapping DEGs in Cu stressed WT and Cu stressed atp7a−/− were identified. GO term analysis showed an enrichment in the genes related to heme binding, implying that Cu was independent of the integral function of atp7a to affect heme binding. In addition, genes involved in the negative regulation of angiogenesis were down-regulated in atp7a−/− mutants with and without Cu stress, which failed to occur in WT, implying that the integral function of atp7a is required for maintaining the normal expression of angiogenesis genes. The integrative data in this study demonstrated that atp7a is required for ion transport and angiogenesis, and for Cu-induced neurexin family protein binding defects, rather than for Cu-induced heme binding defects, during zebrafish embryogenesis. These findings provide possible clues for human diseases with ATP7A dysfunction and imbalanced Cu homeostasis.

The pathogenesis of DLD-mediated cuproptosis induced spinal cord injury and its regulation on immune microenvironment.

Spinal cord injury (SCI) is a severe central nervous system injury that leads to significant sensory and motor impairment. Copper, an essential trace element in the human body, plays a vital role in various biological functions and is strictly regulated by copper chaperones and transporters. Cuproptosis, a novel type of metal ion-induced cell death, is distinct from iron deprivation. Copper deprivation is closely associated with mitochondrial metabolism and mediated by protein fatty acid acylation. In this study, we investigated the effects of cuproptosis-related genes (CRGs) on disease progression and the immune microenvironment in acute spinal cord injury (ASCI) patients. We obtained the gene expression profiles of peripheral blood leukocytes from ASCI patients using the Gene Expression Omnibus (GEO) database. We performed differential gene analysis, constructed protein-protein interaction networks, conducted weighted gene co-expression network analysis (WGCNA), and built a risk model. Our analysis revealed that dihydrolipoamide dehydrogenase (DLD), a regulator of copper toxicity, was significantly associated with ASCI, and DLD expression was significantly upregulated after ASCI. Furthermore, gene ontology (GO) enrichment analysis and gene set variation analysis (GSVA) showed abnormal activation of metabolism-related processes. Immune infiltration analysis indicated a significant decrease in T cell numbers in ASCI patients, while M2 macrophage numbers were significantly increased and positively correlated with DLD expression. In summary, our study demonstrated that DLD affects the ASCI immune microenvironment by promoting copper toxicity, leading to increased peripheral M2 macrophage polarization and systemic immunosuppression. Thus, DLD has potential as a promising biomarker for ASCI, providing a foundation for future clinical interventions.

Effects of dietary copper (Cu) on growth performance, body composition, mineral content, hepatic histology and Cu transport of the GIFT strain of Nile tilapia (Oreochromis niloticus)

This study determined the influence of dietary copper (Cu) levels on growth and feed utilization, body composition, mineral content, liver histology and intestinal Cu transport, and identify dietary Cu requirement of the GIFT strain of Nile tilapia (Oreochromis niloticus). Six diets were prepared with Cu sulfate addition at levels of 0 (control), 5, 10, 20, 40, and 80 mg/kg, respectively. Analytical dietary Cu contents were 1.55, 2.97, 4.51, 7.25, 11.30, and 19.24 mg Cu/kg diet, respectively. Each experimental diet was fed to three replicates of GIFT tilapia (25 fish per tank, initial body weight 4.34 ± 0.01 g) in a recirculating freshwater system for eight weeks. GIFT tilapia fed 4.51 mg Cu/kg diet had higher growth performance and feed utilization. Cu contents in the whole-body, the liver and intestinal tract increased with dietary Cu levels. Moreover, dietary Cu addition also affected whole-body Mg content significantly, but did not affect whole body crude protein, lipid, zinc (Zn), iron (Fe), and calcium (Ca) content. GIFT tilapia fed with 4.51 mg Cu/kg diet had lower liver vacuoles relative area. Furthermore, dietary Cu addition also significantly influenced mRNA expression of genes involved in intestinal Cu transport, such as copper transporter 1 (ctr1), copper transporter 2 (ctr2), antioxidant 1 copper chaperone (atox1), cytochrome c oxidase copper chaperone (cox17) and copper-transporting ATPase alpha (atp7a). The regression analysis of weight gain and whole-body Cu retention against the dietary Cu levels suggested that 4.23 to 4.57 mg Cu/kg diet was optimal for GIFT tilapia. Statement of relevanceOur study determined the optimal dietary Cu requirement of GIFT strain of tilapia, which provided good references for dietary Cu addition for the fish species, and accordingly was helpful for its feed formulation and aquaculture production. Our study also demonstrated that dietary Cu addition influenced mRNA expression of genes involved in Cu transport, which provides a good basis for exploring Cu metabolism in fish.

The critical role of copper homeostasis during the immune response

Abstract Copper homeostasis is tightly regulated in living organisms, as copper is essential to numerous cellular processes but toxic in excess. Dysregulated copper homeostasis is associated with numerous human diseases, including genetic diseases of copper transport, cancer, autoimmune disease, and infection. Although patients with mutations in copper transporters have an increased susceptibility to infection, little is known about the changes in immune function in these diseases. Further, altering copper availability has shown promise in treating either autoimmunity or infection, but the mechanisms underlying this effect are unresolved. We examined serum copper levels in human samples during acute influenza or SARS-CoV-2 virus infections, revealing unique virus-dependent copper dynamics. As copper is required for important immune cell processes such as metabolism, signaling and maintenance of reactive oxygen species, we next investigated the effect of modulating copper levels on T cell activation. We found that copper chelation impaired T cell proliferation, reduced expression of T cell activation markers, and altered gene expression following stimulation. To determine the impact of copper levels during the immune response in vivo, we then treated mice with copper chelation prior to and during an influenza A virus infection. Notably, mice treated with copper chelation prior to infection had altered serum copper dynamics, greater weight loss, and more flu-specific T cells compared to untreated mice. Overall, our results demonstrate the importance of copper homeostasis during the immune response. Ongoing experiments will investigate the mechanisms underlying this role in immune function during disease. Supported by ALSAC and NIH (5T32AI106700).

SLC31 family of copper transporters in GtoPdb v.2023.1

SLC31 family members, alongside the Cu-ATPases are involved in the regulation of cellular copper levels. The CTR1 transporter is a cell-surface transporter to allow monovalent copper accumulation into cells, while CTR2 appears to be a vacuolar/vesicular transporter [5]. Functional copper transporters appear to be trimeric with each subunit having three TM regions and an extracellular N-terminus. CTR1 is considered to be a higher affinity copper transporter compared to CTR2. The stoichiometry of copper accumulation is unclear, but appears to be energy-independent [4].

Pigmentation and TYRP1 expression are mediated by zinc through the early secretory pathway-resident ZNT proteins

Tyrosinase (TYR) and tyrosinase-related proteins 1 and 2 (TYRP1 and TYRP2) are essential for pigmentation. They are generally classified as type-3 copper proteins, with binuclear copper active sites. Although there is experimental evidence for a copper cofactor in TYR, delivered via the copper transporter, ATP7A, the presence of copper in TYRP1 and TYRP2 has not been demonstrated. Here, we report that the expression and function of TYRP1 requires zinc, mediated by ZNT5–ZNT6 heterodimers (ZNT5–6) or ZNT7–ZNT7 homodimers (ZNT7). Loss of ZNT5–6 and ZNT7 function results in hypopigmentation in medaka fish and human melanoma cells, and is accompanied by immature melanosomes and reduced melanin content, as observed in TYRP1 dysfunction. The requirement of ZNT5–6 and ZNT7 for TYRP1 expression is conserved in human, mouse, and chicken orthologs. Our results provide novel insights into the pigmentation process and address questions regarding metalation in tyrosinase protein family.

Structures of the human Wilson disease copper transporter ATP7B

The P-type ATPase ATP7B exports cytosolic copper and plays an essential role in the regulation of cellular copper homeostasis. Mutants of ATP7B cause Wilson disease (WD), an autosomal recessive disorder of copper metabolism. Here, we present cryoelectron microscopy (cryo-EM) structures of human ATP7B in the E1 state in the apo, the putative copper-bound, and the putative cisplatin-bound forms. In ATP7B, the N-terminal sixth metal-binding domain (MBD6) binds at the cytosolic copper entry site of the transmembrane domain (TMD), facilitating the delivery of copper from the MBD6 to the TMD. The sulfur-containing residues in the TMD of ATP7B mark the copper transport pathway. By comparing structures of the E1 state human ATP7B and E2-Pi state frog ATP7B, we propose the ATP-driving copper transport model of ATP7B. These structures not only advance our understanding of the mechanisms of ATP7B-mediated copper export but can also guide the development of therapeutics for the treatment of WD.

Atp7b deficiency induces zebrafish eye developmental defects.

As a copper (Cu) transport ATPase, ATP7B plays an important role in maintaining Cu homeostasis in the body and its dysfunction is associated with retinal disease. How ATP7B dysfunction and the subsequent Cu overload induce retinal damage, however, are unknown. Here, we show that atp7b-/- homozygous zebrafish larvae are insensitive to light stimulation, with a reduction in retinal cells but normal like morphological phenotypes. Additionally, a series of differentially expressed genes are unveiled in atp7b-/- mutated larvae, which enrich in photo-transduction, structural constituent of eye lens, sensory perception of light stimulus, oxidative phosphorylation, and ATPase activity. Moreover, we show the Cu accumulation in retinal cells in atp7b-/- mutated larvae, which results in endoplasmic reticulum (ER) stress and retinal cell apoptosis and subsequent retinal defects. The integral data in this study demonstrate that atp7b mutation leads to Cu accumulation in zebrafish retinal cells and the consequence ER stress and retinal cell death. These data may give some possible hints to explain retinal disease occurred in the Cu dysregulation syndromes Wilson's disease with ATP7B mutation.

Arabidopsis COPT1 copper transporter uses a single histidine to regulate transport activity and protein stability

Copper acquisition and subsequent delivery to target proteins are essential for many biological processes. However, the cellular levels of this trace element must be controlled because of its potential toxicity. The COPT1 protein rich in potential metal-binding amino acids functions in high affinity copper uptake at the plasma membrane of Arabidopsis cells. The functional role of these putative metal-binding residues is largely unknown. Through truncations and site-directed mutagenesis, we identified His43, a single residue within the extracellular N-terminal domain as absolutely critical for copper uptake of COPT1. Substitution of this residue with leucine, methionine or cysteine almost inactivated transport function of COPT1, implying that His43 fails to serves as a copper ligand in the regulation of COPT1 activity. Deletion of all extracellular N-terminal metal-binding residues completely blocked copper-stimulated degradation but did not alter the subcellular distribution and multimerization of COPT1. Although mutation of His43 to alanine and serine retained the transporter activity in yeast cells, the mutant protein was unstable and degraded in the proteasome in Arabidopsis cells. Our results demonstrate a pivotal role for the extracellular residue His43 in high affinity copper transport activity, and suggest common molecular mechanisms for regulating both metal transport and protein stability of COPT1.

Lead exposure disturbs ATP7B-mediated copper export from brain barrier cells by inhibiting XIAP-regulated COMMD1 protein degradation

The brain barrier is an important structure for metal ion homeostasis. According to studies, lead (Pb) exposure disrupts the transportation of copper (Cu) through the brain barrier, which may cause impairment of the nervous system; however, the specific mechanism is unknown. The previous studies suggested the X-linked inhibitor of apoptosis (XIAP) is a sensor for cellular Cu level which mediate the degradation of the MURR1 domain-containing 1 (COMMD1) protein. XIAP/COMMD1 axis was thought to be an important regulator in Cu metabolism maintenance. In this study, the role of XIAP-regulated COMMD1 protein degradation in Pb-induced Cu disorders in brain barrier cells was investigated. Pb exposure significantly increased Cu levels in both cell types, according to atomic absorption technology testing. Western blotting and reverse transcription PCR (RT-PCR) showed that COMMD1 protein levels were significantly increased, whereas XIAP, ATP7A, and ATP7B protein levels were significantly decreased. However, there were no significant effects at the messenger RNA (mRNA) level (XIAP, ATP7A, and ATP7B). Pb-induced Cu accumulation and ATP7B expression were reduced when COMMD1 was knocked down by transient small interfering RNA (siRNA) transfection. In addition, transient plasmid transfection of XIAP before Pb exposure reduced Pb-induced Cu accumulation, increased COMMD1 protein levels, and decreased ATP7B levels. In conclusion, Pb exposure can reduce XIAP protein expression, increase COMMD1 protein levels, and specifically decrease ATP7B protein levels, resulting in Cu accumulation in brain barrier cells.

Abstract 1687: ATPase copper transporting beta (ATP7B) contributes to acquired docetaxel resistance in human prostate cancer

Abstract Docetaxel has been the standard first-line chemotherapy for lethal metastatic prostate cancer (mPCa) since 2004, but the resistance to docetaxel treatment is common. The molecular mechanisms of docetaxel resistance remain largely unknown and could be amenable to interventions that mitigate resistance. We have recently discovered that several docetaxel resistant mPCa cell lines exhibit less uptake of cellular copper and express markedly higher levels of ATP7B protein without significant changes in the protein expression levels of other copper transporters, such as ATPase copper transporting alpha (ATP7A) and high affinity copper uptake protein 1 (CTR1). Knock-down of ATP7B by silencing RNAs sensitized docetaxel resistant-mPCa cells to the growth inhibitory and apoptotic effects of docetaxel. Importantly, deletions of ATP7B in mPCa tissues predict significantly better survival of patients after their first chemotherapy than those with wild-type ATP7B (P = 0.0006). In addition, Disulfiram (DSF), an FDA approved drug for treatment of alcohol dependence, in combination with copper, significantly enhanced the in vivo antitumor effects of docetaxel in a docetaxel resistant xenograft tumor model. Our analyses also revealed that DSF and copper engaged with ATP7B to decrease protein levels of COMM domain-containing protein 1 (COMMD1), S-phase kinase associated protein 2 (Skp2) and clusterin and markedly increase protein expression of cyclin-dependent kinase inhibitor 1 (p21/WAF1). Taken together, our results suggest that ATP7B is a clinically relevant and key target for improving the efficacy of docetaxel for treatment of mPCa. Citation Format: Liankun Song, Vyvyan Nguyen, Jun Xie, Matthew Tippin, Le TP Truong, Christopher A. Blair, Beverly Wang, Edward Uchio, Xiaolin Zi. ATPase copper transporting beta (ATP7B) contributes to acquired docetaxel resistance in human prostate cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 1687.