Copper Overload Disorder Research Articles

Abstract 2673: Copper chelation overcomes the immunosuppressive neuroblastoma microenvironment to potentiate anti-GD2 antibody therapy

Abstract Neuroblastoma is the most frequent extra-cranial pediatric cancer with high-risk disease possessing a dismal five-year survival rate <50%. Antibody-based therapies targeting the surface disialoganglioside GD2 have shown promising anti-tumor activity in patients however efficacy is strongly hampered by immunosuppressive mechanisms present in the tumor microenvironment. Neuroblastomas typically feature low mutational burdens, limited major histocompatibility complex class I expression, increased immune checkpoint markers, sparse immune infiltration, and soluble mediators which drastically limit anti-tumor immunity. Given the emerging link between elevated copper levels and tumoral immune evasion, we explored copper chelation as a therapeutic strategy using the agents tetraethylenepentamine (TEPA) and the clinically approved analogue triethylenetetramine (TETA). Using the immunocompetent TH-MYCN model, we performed single-cell RNA sequencing supported by OPAL multiplex immunohistochemistry and cytokine profiling of resected tumors to assess cellular and molecular changes occurring after one week of TEPA treatment. Therapy was observed to successfully deplete intratumoral copper and reinvigorate anti-tumor immunity with increased infiltration and activity of pro-inflammatory immune cells, and was specifically found to induce egress and N1-polarisation of neutrophils. Further mechanistic studies in vitro revealed the sequestration of copper by neuroblastoma cells attenuated neutrophil function, which could be successfully reversed upon TEPA treatment. Findings propose a novel mechanism of immune evasion, highlighting copper chelation as a therapeutic strategy to counteract immunosuppression. Using the TH-MYCN model, TEPA was employed as a priming agent to effectively potentiate anti-GD2 antibody therapy and achieve durable tumor control. Importantly, this was associated with increased Fc-receptor-bearing natural killer and myeloid cells, which elicit tumor clearance via antibody-dependent cellular cytotoxicity. Currently indicated for the treatment of copper overload disorder Wilson’s disease, TETA was evaluated for potential repurposing as a novel immunomodulatory agent. Using the syngeneic NXS2 model, TETA exhibited an exceptional safety profile and combination therapy achieved durable tumor control with no relapses occurring after treatment cessation. This result was similarly associated with the infiltration of pro-inflammatory immune cells, including N1 neutrophils. Collectively, this study credentials copper chelation as a non-toxic strategy to disrupt the immunosuppressive tumor microenvironment and reinvigorate anti-tumour immunity. Findings provide crucial translational evidence for repurposing TETA to potentiate anti-GD2 antibody therapy and improve neuroblastoma patient responses. Citation Format: Jourdin R. Rouaen, Antonella Salerno, Fabio Luciani, Jayne Murray, Tyler Shai-Hee, Nicodemus Tedla, Michelle Haber, Toby N. Trahair, Orazio Vittorio. Copper chelation overcomes the immunosuppressive neuroblastoma microenvironment to potentiate anti-GD2 antibody therapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 2673.

Challenges in the diagnosis of Wilson disease.

The understanding and management of Wilson disease (WD) have dramatically improved since the first description of the disease by K. Wilson more than a century ago. However, the persistent long delay between the first symptoms and diagnosis emphasizes challenges in diagnosing earlier this copper overload disorder. As a treatable disease, WD should be detected early in the course of the disease by any health professionals at any care level, but the rare prevalence of the disease explains the lack of awareness of referring physicians. The most important challenge is to train physicians to recognize atypical or rare symptoms of WD that will lead to discuss the diagnosis more systematically. Atypia can come from the age of onset, the liver [non-alcoholic steatohepatitis (NASH) presentation], the central or peripheral nervous system (neuropathy, epilepsy, sleep disorders…) or may be due to lesions of other organs (renal manifestations, osteo-articular disorders or endocrine disturbances). Isolated biological anomalies, rare radiological findings or inadequate interpretation of copper test may also lead to misdiagnosis. The second challenge is to confirm the diagnosis faster and more effectively so as not to delay the initiation of treatment, and expand family screening as the genetic prevalence is higher than previously expected. Generalization of the exchangeable copper assay and the next generation sequencing (NGS) are two promising ways to overcome this ultimate challenge. By drawing attention to the earliest and rare symptoms and to new biomarkers and diagnostic tools, we hope that this article will increase diagnostic awareness and reduce delays so that patients can start their treatment earlier in the course of the illness and thus have a better disease prognosis.

Chapter 19 - Novel perspectives on Wilson disease treatment

Wilson disease is an autosomal-recessive copper overload disorder causing hepatic and neurologic symptoms. Commonly used medical therapy shows satisfactory results with regard to hepatic disease but only limited effects in neurologically affected patients. In recent years several new therapy options have been developed, showing promising results that might improve the management of Wilson disease in the near future. Optimization of treatment regimens depending on biochemical response pattern seems worthwhile, especially in the decoppering phase of therapy. The chelator tetrathiomolybdate (TTM) is a promising therapy option, currently under clinical investigation. TTM is a fast-acting and very potent chelator and appears to be associated with early neurologic deterioration after initiation of therapy to a lower extent than the drugs currently used. Treatment with nonchelating drugs characterized by alternative modes of action is under investigation, but restricted to animal or in vitro studies to date. This includes basic research studies demonstrating proof of principle for successful cell or gene therapy in Wilson disease in order to restore sufficient biliary copper excretion, even before the onset of disease.

Tetrathiomolybdate inhibits mitochondrial complex IV and mediates degradation of hypoxia-inducible factor-1α in cancer cells.

Hypoxia-inducible factor-1α (HIF-1α) is a transcription factor that triggers adaptive responses upon low oxygen conditions and plays a crucial role in cancer metabolism and therapy resistance. Tetrathiomolybdate (TM), a therapy option for copper overload disorder, has also been shown to be capable of limiting tumor angiogenesis, although its underlying mechanism remains unclear. Using ovarian and endometrial cancer cell lines, we observed that TM downregulates HIF-1α protein levels and HIF-transcriptional targets involved in tumor angiogenesis and glycolysis, but did not affect HIF-1α protein synthesis. TM-mediated HIF-1α downregulation was suppressed when HIF-prolyl hydroxylase activity was pharmacologically inhibited using deferoxamine or dimethyloxaloylglycine, and also when the oxygen-dependent degradation domains of HIF-1α, which are responsible for the interaction with HIF-prolyl hydroxylase, were deleted. These findings suggest that TM causes HIF-1α downregulation in a HIF-prolyl hydroxylase-dependent manner. Our studies showed that TM inhibits the activity of the copper-dependent mitochondrial complex IV and reduces mitochondrial respiration, thereby possibly increasing oxygen availability, which is crucial for HIF-prolyl hydroxylase activity. Pimonidazole staining also showed that TM elevates oxygen tension in hypoxic cells. Our studies provide mechanistic evidence for TM-mediated HIF-1α regulation and suggest its therapeutic potential as a method of blocking angiogenesis in ovarian and endometrial tumors.

Clinical considerations for an effective medical therapy in Wilson's disease.

Wilson's disease is an autosomal recessively inherited copper overload disorder that leads to hepatic and/or neurologic symptoms. More than a century after the first description of Wilson's disease, the available medical treatment options have not been standardized. The efficacy of the commonly used drugs is satisfactory for hepatic disease, but disappointing in the neurologic patients, including the risk of neurologic deterioration after the initiation of chelation therapy. An approach to overcome this problem is the careful and systematic assessment of biochemical response patterns and the quantitative monitoring of symptoms using validated rating scales. Standardized dosage strategies that address changes in copper pools might improve adherence and reduce side effects. Such an approach may reduce long-term morbidity. In this paper, we discuss considerations for an effective medical treatment and requirements for future studies in Wilson's disease.

Hepatobiliary malignancies in Wilson disease

Wilson disease (WD) is a rare inherited copper overload disorder leading to chronic liver failure. While hepatobiliary malignancies are common in patients with chronic end stage liver diseases, reports on liver tumors in Wilson disease patients are scarce. The present study aims to determine the frequency and type of hepatobiliary malignancies in WD patients.

Tetrathiomolybdate sensitizes ovarian cancer cells to anticancer drugs doxorubicin, fenretinide, 5-fluorouracil and mitomycin C

BackgroundOur recent study showed that tetrathiomolybdate (TM), a drug to treat copper overload disorders, can sensitize drug-resistant endometrial cancer cells to reactive oxygen species (ROS)-generating anticancer drug doxorubicin. To expand these findings in the present study we explore TM efficacy in combination with a spectrum of ROS-generating anticancer drugs including mitomycin C, fenretinide, 5-fluorouracil and doxorubicin in ovarian cancer cells as a model system.MethodsThe effects of TM alone or in combination with doxorubicin, mitomycin C, fenretinide, or 5-fluorouracil were evaluated using a sulforhodamine B assay. Flow cytometry was used to detect the induction of apoptosis and ROS generation. Immunoblot analysis was carried out to investigate changes in signaling pathways.ResultsTM potentiated doxorubicin-induced cytotoxicity and modulated key regulators of apoptosis (PARP, caspases, JNK and p38 MAPK) in SKOV-3 and A2780 ovarian cancer cell lines. These effects were linked to the increased production of ROS, as shown in SKOV-3 cells. ROS scavenging by ascorbic acid blocked the sensitization of cells by TM. TM also sensitized SKOV-3 to mitomycin C, fenretinide, and 5-fluorouracil. The increased cytotoxicity of these drugs in combination with TM was correlated with the activity of ROS, loss of a pro-survival factor (e.g. XIAP) and the appearance of a pro-apoptotic marker (e.g. PARP cleavage).ConclusionsOur data show that TM increases the efficacy of various anticancer drugs in ovarian cancer cells in a ROS-dependent manner.

Evolving Perspectives in Wilson Disease: Diagnosis, Treatment and Monitoring

Wilson disease (WD), the autosomal recessively inherited copper overload disorder, remains a diagnostic and therapeutic challenge. In the last decade, direct sequencing of the affected gene ATP7B became commercially available, but interpretation of the results still requires careful attention. Thus, a combination of tests reflecting the disturbed copper metabolism is needed to make the final diagnosis. Because of the low disease frequency, the existing treatment concepts are not based on controlled trails. Here, recent outcome reports of larger cohort studies challenge the recommended therapies and call for individualized treatment strategies. The notion, that certain medical regimens may either be insufficient to upkeep copper homeostasis or may lead to a clinically relevant overtreatment, demand a continuous monitoring of patients even after decades of therapy. In this article, we review current diagnostic and therapeutic approaches in WD.

Genetic analysis of BIRC4/XIAP as a putative modifier gene of Wilson disease

Wilson disease (WD) is an autosomal-recessive copper overload disorder caused by mutations in the copper-transporting adenosine triphosphatase (ATPase) ATP7B. It presents with a highly variable clinical phenotype ranging from asymptomatic to fulminant hepatic failure or progressive neurological involvement. No clear genotype-phenotype correlation has been established. Thus, variants in modifier genes could have an impact on WD manifestation and severity. Recently, the antiapoptotic protein baculoviral IAP repeat-containing protein 4 BIRC4/XIAP has been suggested as a regulator of copper-induced cell death. With the aim of investigating a putative role of BIRC4/XIAP as modifier gene in individuals with copper overload, we analyzed a WD patient cohort (n = 98) for sequence variants at the BIRC4/XIAP locus. When compared with clinical data, the previously described coding single nucleotide polymorphisms (SNPs) at the BRIC4/XIAP locus (rs28382721, rs28382722, rs28382723, rs5956583, rs28382740, rs12838858, rs28382741) did not correlate with age of onset or clinical presentation in our collective. However, three previously unreported variants in the BIRC4/XIAP gene were identified (c.1-26 T > G; c.1408A > T; p.T470S; c.1019A > G; p.N340S). The two patients with variants leading to amino acid exchanges in the BIRC4/XIAP protein showed a remarkably early disease onset at the age of 5 years. Furthermore, one of these patients was only heterozygous for disease-causing mutations in the ATP7B gene. In summary, these data emphasize the need to further elucidate a role of BIRC4/XIAP variants as putative pathogenetic factors in copper overload disorders.

Reduced expression of ATP7B affected by Wilson disease-causing mutations is rescued by pharmacological folding chaperones 4-phenylbutyrate and curcumin

Wilson disease (WD) is an autosomal recessive copper overload disorder of the liver and basal ganglia. WD is caused by mutations in the gene encoding ATP7B, a protein localized to the trans-Golgi network that primarily facilitates hepatic copper excretion. Current treatment comprises reduction of circulating copper by zinc supplementation or copper chelation. Despite treatment, a significant number of patients have neurological deterioration. The aim of this study was to investigate the possibility that defects arising from some WD mutations are ameliorated by drug treatment aimed at improvement of protein folding and restoration of protein function. This necessitated systematic characterization of the molecular consequences of distinct ATP7B missense mutations associated with WD. With the exception of p.S1363F, all mutations tested (p.G85V, p.R778L, p.H1069Q, p.C1104F, p.V1262F, p.G1343V, and p.S1363F) resulted in reduced ATP7B protein expression, whereas messenger RNA abundance was unaffected. Retention of mutant ATP7B in the endoplasmic reticulum, increased protein expression, and normalization of localization after culturing cells at 30 degrees C, and homology modeling suggested that these proteins were misfolded. Four distinct mutations exhibited residual copper export capacity, whereas other mutations resulted in complete disruption of copper export by ATP7B. Treatment with pharmacological chaperones 4-phenylbutyrate (4-PBA) and curcumin, a clinically approved compound, partially restored protein expression of most ATP7B mutants. These findings might enable novel treatment strategies in WD by directly enhancing the protein expression of mutant ATP7B with residual copper export activity. 1795.).

Increased activity of hypoxia-inducible factor 1 is associated with early embryonic lethality in Commd1 null mice.

COMMD1 (previously known as MURR1) belongs to a novel family of proteins termed the copper metabolism gene MURR1 domain (COMMD) family. The 10 COMMD family members are well conserved between vertebrates, but the functions of most of the COMMD proteins are unknown. We recently established that COMMD1 is associated with the hepatic copper overload disorder copper toxicosis in Bedlington terriers. Recent in vitro studies indicate that COMMD1 has multiple functions, including sodium transport and NF-kappaB signaling. To elucidate the function of Commd1 in vivo, we generated homozygous Commd1 null (Commd1(-/-)) mice. Commd1(-/-) embryos died in utero between 9.5 and 10.5 days postcoitum (dpc), their development was generally retarded, and placenta vascularization was absent. Microarray analysis identified transcriptional upregulation of hypoxia-inducible factor 1 (HIF-1) target genes in 9.5-dpc Commd1(-/-) embryos compared to normal embryos, a feature that was associated with increased Hif-1alpha stability. Consistent with these observations, COMMD1 physically associates with HIF-1alpha and inhibits HIF-1alpha stability and HIF-1 transactivation in vitro. Thus, this study identifies COMMD1 as a novel regulator of HIF-1 activity and shows that Commd1 deficiency in mice leads to embryonic lethality associated with dysregulated placenta vascularization.

Perspectives for Gene Therapy of Wilson Disease

Wilson disease is a rare autosomal-recessive copper overload disorder due to mutations of the Wilson disease gene ATP7B. The disease typically manifests at late childhood or in young adults with hepatic and/or neurological symptoms. Being fatal without medical treatment or liver transplantation the long-term outcome of Wilson disease depends on the adherence to an effective treatment. Because current medical treatment options are not effective in all Wilson disease patients and adherence to therapy is a problem, gene therapy might represent an alternative curative future therapy. In the rat model of Wilson disease adenoviral and lentiviral gene transfer studies could prove that viral gene transfer is therapeutically effective and can reverse clinical symptoms. However, both approaches were limited by a more or less transient transgene expression. As several tactics can be used to overcome these current limitations, gene therapy approaches may become more efficient than standard medical treatment for Wilson disease in the future. This review discusses both, existing vectors and strategies and prospective developments towards liver-directed gene therapy, although there is still a long way to go until gene therapy can be used for safe treatment of Wilson disease in humans.

Several COMMD proteins interact with ATP7B; possible candidate genes for hepatic copper overload disorders with unknown etiology

de Bie, P1 2; Burstein, E3; van de Sluis, B1 2; Berger, R1; Wijmenga, C2; Duckett, CS3 4; Klomp, LWJ1Author Information

Current and future therapy in haemochromatosis and Wilson?s disease

There have been several new developments in the treatment of iron and copper overload disorders, such as haemochromatosis, thalassaemia and Wilson’s disease. Clinical trials of orally administered iron chelators, both as monotherapy and in combination with deferoxamine, are in progress around the world. Several new chelators are now being introduced in clinical trials. Future therapies for iron overload may comprise of oral iron binding agents capable of preventing dietary iron absorption from the diet. The characterisation of specific iron transporters such as the divalent metallic transporter and ferroportin may hold promise for the development of ‘smart’ compounds capable of blocking iron transport. Several new agents are now available for the management of Wilson’s disease, including trientine, zinc and tetrathiomolybdate. This review, will discuss the pathogenesis, and current and future therapies for iron and copper overload disorders.

Animal models of Wilson's disease.

Wilson’s disease is an autosomal recessive, copper overload disorder, characterised by the co-existence of progressive neurological findings, chronic liver disease with cirrhosis, renal tubular dysfunction and pigmented corneal rings. The concentration of copper in the liver may be of the order of 200 – 3000 μg/g dry weight whereas the concentration in the liver of normal adults varies from 20 – 50 μg/g dry weight. (Danks 1995; Seymour 1987). The gene for Wilson’s disease (ATP7B) maps to the long arm of chromosome 13 (Bowcock et al, 1987; Yuzbasiyan-Gurkan et al., 1987) and encodes a putative P type copper transporting ATPase (Bull et al., 1993; Tanzi et al., 1993). In humans the gene is expressed in liver, kidney, placenta and brain (Bull et al., 1993; Tanzi et al., 1993), and the mutations causing Wilson’s disease have been found to be single base changes or small deletions causing frame shifts and protein truncations (Thomas et al., 1995). The disease was first described by Wilson (1912) as a familial neurological disorder, which he called lenticular degeneration. He was far sighted enough to note that “the morbid agent is probably a toxin associated with hepatic cirrhosis”. It took thirty years for the association with copper overload to be established and it took eighty years before the gene was determined. It has been found useful to break Wilson’s disease down into 4 stages which are: Presymptomatic, in which copper accumulates and there are no clinical signs; Copper Toxic, in which signs are present and, if untreated, the patient will die; Symptomatic but treated, in which the patient is recovering and Maintenance therapy, in which there is clinical stability but anticopper medication must continue (Brewer and Yuzbasian-Gurkan, 1989).

Oxidant injury to hepatic mitochondrial lipids in rats with dietary copper overload: Modification by vitamin E deficiency

To examine the role of oxidant damage to subcellular membranes in the pathogenesis of copper hepatotoxicity, the effects of dietary copper overload and varying states of vitamin E on biochemical, histological, and ultrastructural features of rat liver were investigated. Weanling male rats were pair-fed for 8 weeks on diets containing normal or high levels of copper in combination with either deficient, sufficient, or excessive vitamin E. Hepatic microsomes and mitochondria, isolated by differential centrifugation, showed similar enrichment and recovery among all experimental groups. Evidence of in vivo peroxidation of membrane lipids (generation of conjugated dienes and thiobarbituric acid reacting substances) was present in mitochondrial but not microsomal preparations from copper-overloaded rats. Serum aspartate aminotransferase, alanine aminotransferase, and cholylglycine (which were increased in all copper-overloaded rats), as well as mitochondrial thiobarbituric acid-reacting substances, were more elevated in vitamin E-deficient rats. In copperoverloaded rats, liver histology showed changes of acute and chronic hepatocyte injury with mild periportal fibrosis; electron microscopy showed abundant copper-containing lysosomes and dilated cristae of hepatocyte mitochondria, findings similar to those in the liver of humans with copper-overload disorders. These findings suggest that an oxidant injury to hepatocyte mitochondria may be one of the initiating factors in hepatocellular damage that leads to hepatic lesions in copper-overload states in humans.