Triethylenetetramine pharmacology and its clinical applications

Chelating mitochondrial iron and copper: Recipes, pitfalls and promise

Iron and copper chelation therapy plays a crucial role in treating conditions associated with metal overload, such as hemochromatosis or Wilson's disease. However, conventional chelators face challenges in reaching the core of iron and copper metabolism - the mitochondria. Mitochondria-targeted chelators can specifically target and remove metal ions from mitochondria, showing promise in treating diseases linked to mitochondrial dysfunction, including neurodegenerative diseases and cancer. Additionally, they serve as specific mitochondrial metal sensors. However, designing these new molecules presents its own set of challenges. Depending on the chelator's intended use to prevent or to promote redox cycling of the metals, the chelating moiety must possess different donor atoms and an optimal value of the electrode potential of the chelator-metal complex. Various targeting moieties can be employed for selective delivery into the mitochondria. This review also provides an overview of the current progress in the design of mitochondria-targeted chelators and their biological activity investigation.

Evolving approaches in glioma treatment: harnessing the potential of copper metabolism modulation

The key properties and high versatility of metal nanoparticles have shed new perspectives on cancer therapy, with copper nanoparticles gaining great interest because of the ability to couple the intrinsic properties of metal nanoparticles with the biological activities of copper ions in cancer cells. Copper, indeed, is a cofactor involved in different metabolic pathways of many physiological and pathological processes. Literature data report on the use of copper in preclinical protocols for cancer treatment based on chemo-, photothermal-, or copper chelating-therapies. Copper nanoparticles exhibit anticancer activity via multiple routes, mainly involving the targeting of mitochondria, the modulation of oxidative stress, the induction of apoptosis and autophagy, and the modulation of immune response. Moreover, compared to other metal nanoparticles (e.g. gold, silver, palladium, and platinum), copper nanoparticles are rapidly cleared from organs with low systemic toxicity and benefit from the copper's low cost and wide availability. Within this review, we aim to explore the impact of copper in cancer research, focusing on glioma, the most common primary brain tumour. Glioma accounts for about 80% of all malignant brain tumours and shows a poor prognosis with the five-year survival rate being less than 5%. After introducing the glioma pathogenesis and the limitation of current therapeutic strategies, we will discuss the potential impact of copper therapy and present the key results of the most relevant literature to establish a reliable foundation for future development of copper-based approaches.

Challenges and dilemmas in pediatric hepatic Wilson's disease

Wilson disease is an autosomal recessive disorder affecting the ATP7B gene located on chromosome 13q. This leads to copper deposition in various organs, most importantly in the liver and brain. The genetic mutations are vast, well reported in the West but poorly documented in developing countries. Hence the diagnosis is made with a constellation of clinico-laboratory parameters which have significant overlap with other liver diseases and often pose a significant dilemma for clinicians. Diagnostic scoring systems are not fool-proof. The availability and affordability of chelators in developing countries impact the drug compliance of patients. While D-penicillamine is a potent drug, its side effects lead to drug discontinuation. Trientine is cost-prohibitive in developing countries. There is no single test to assess the adequacy of chelation. Exchangeable urinary copper is an essential upcoming diagnostic and prognostic tool. In the presence of cirrhosis, hypersplenism clouds the assessment of myelosuppression of drugs. Similarly, it may be difficult to distinguish disease tubulopathy from drug-induced glomerulonephritis. Neurological worsening due to chelators may appear similar to disease progression. Presentation as fulminant hepatic failure requires rapid workup. There is a limited window of opportunity to salvage these patients with the help of plasmapheresis and other liver-assisted devices. This review addresses the challenges and clinical dilemmas faced at beside in developing countries.

Effect of Copper Chelators via the TGF-β Signaling Pathway on Glioblastoma Cell Invasion

Glioblastoma multiforme (GBM) is a fast-growing and aggressive type of brain cancer. Unlike normal brain cells, GBM cells exhibit epithelial-mesenchymal transition (EMT), which is a crucial biological process in embryonic development and cell metastasis, and are highly invasive. Copper reportedly plays a critical role in the progression of a variety of cancers, including brain, breast, and lung cancers. However, excessive copper is toxic to cells. D-penicillamine (DPA) and triethylenetetramine (TETA) are well-known copper chelators and are the mainstay of treatment for copper-associated diseases. Following treatment with copper sulfate and DPA, GBM cells showed inhibition of proliferation and suppression of EMT properties, including reduced expression levels of N-cadherin, E-cadherin, and Zeb, which are cell markers associated with EMT. In contrast, treatment with copper sulfate and TETA yielded the opposite effects in GBM. Genes, including TGF-β, are associated with an increase in copper levels, implying their role in EMT. To analyze the invasion and spread of GBM, we used zebrafish embryos xenografted with the GBM cell line U87. The invasion of GBM cells into zebrafish embryos was markedly inhibited by copper treatment with DPA. Our findings suggest that treatment with copper and DPA inhibits proliferation and EMT through a mechanism involving TGF-β/Smad signaling in GBM. Therefore, DPA, but not TETA, could be used as adjuvant therapy for GBM with high copper concentrations.

Functionalised electrospun membranes (TETA-PVC) for the removal of lead(ii) from water

Driven by the need for delivering sustainable water purification solutions for the removal of heavy metals from water, electrospun PVC membranes were functionalised with triethylenetetramine (TETA) and were used to remove lead(ii) ions selectively from water. The membranes were characterised and their adsorption behavior towards the removal of lead from water was investigated. The incorporation of TETA on the membrane's surface significantly improved the removal efficiency of lead(ii) up to 99.8% in 30 minutes and under ambient conditions, with the lowest concentration of 50 ppm. The adsorption mechanism was investigated and kinetic data showed a better correlation with the pseudo-second-order model. Similarly, the equilibrium data best fitted with the Langmuir adsorption isotherm model with a relatively high maximum adsorption capacity of 1250 mg g⁻¹ for lead(ii) ions, larger than recently reported adsorption capacities for similar membranes. The functionalised membrane also showed high selectivity to lead(ii) in a mixed solution containing lead(ii), mercury(ii), cadmium(ii), arsenic(iii), copper(ii), and zinc(ii). The functionalised membrane was regenerated, where desorption of lead(ii) was achieved, under mildly acidic conditions. The removal efficiency of the regenerated membrane after six cycles of adsorption/desorption was maintained at a high level of 98%. The proposed design offers a simple yet effective, sustainable, and environmentally friendly solution for water treatment.

Driven by the need for delivering sustainable water purification solutions for the removal of heavy metals from water, TETA functionalised electrospun PVC membranes were fabricated and used to remove lead(ii) ions selectively from water.

Chelation therapy in liver diseases of childhood: Current status and response

Chelation is the mainstay of therapy in certain pediatric liver diseases. Copper and iron related disorders require chelation. Wilson’s disease (WD), one of the common causes of cirrhosis in children is treated primarily with copper chelating agents like D-penicillamine and trientine. D-Penicillamine though widely used due its high efficacy in hepatic WD is fraught with frequent adverse effects resulting discontinuation. Trientine, an alternative drug has comparable efficacy in hepatic WD but has lower frequency of adverse effects. The role of ammonium tetra-thiomolybdate is presently experimental in hepatic WD. Indian childhood cirrhosis is related to excessive copper ingestion, rarely seen in present era. D-Penicillamine is effective in the early part of this disease with reversal of clinical status. Iron chelators are commonly used in secondary hemochromatosis of liver in hemolytic anemias. There are strict chelation protocols during bone marrow transplant. The role of iron chelation in neonatal hemochromatosis is presently not in vogue due to its poor efficacy and availability of other modalities of therapy. Hereditary hemochromatosis is rare in children and the use of iron chelators in this condition is limited.

Comparison of the Pharmacokinetic Profiles of Trientine Tetrahydrochloride and Trientine Dihydrochloride in Healthy Subjects

BACKGROUND AND OBJECTIVE

Wilson disease (WD) is an autosomal recessive inherited disorder of copper metabolism. Chelation of excessive copper is recommended but data on the pharmacokinetics of trientine are limited. The aim of this study was to compare the pharmacokinetics of a new trientine tetrahydrochloride formulation (TETA 4HCl) with those of an established trientine dihydrochloride (TETA 2HCl) salt.

METHODS

A randomised single-centre crossover study to evaluate the pharmacokinetics, safety and tolerability of two different oral formulations of trientine (TETA 4HCl tablets vs TETA 2HCl capsules) in 23 healthy adult subjects receiving a single dose equivalent to 600 mg of trientine base was performed.

RESULTS

Following oral administration, the median time to reach maximum plasma concentration (T_max) was 2.00 h (TETA 4HCl) and 3.00 h (TETA 2HCl). The rate (maximum plasma concentration [C_max]) and extent (area under the plasma concentration-time curve from time zero to infinity [AUC_0-∞]) of absorption of the active moiety, trientine, were greater (by approximately 68% and 56%, respectively) for TETA 4HCl than for the TETA 2HCl formulation. The two formulations presented a similar terminal elimination rate (λ_z) and a similar terminal half-life (t_½) for trientine. Differences between TETA 4HCl and TETA 2HCl in the levels of the two main mono- and diacetylated metabolites were less than seen for trientine. For both tested formulations, healthy male volunteers demonstrated higher trientine plasma levels but lower mono- and diacetylated metabolite levels compared with females, with no sex differences in terminal half-life (t_½) observed. Single oral doses of both formulations were safe and well tolerated.

CONCLUSIONS

Compared with an identical dose of a TETA 2HCl formulation, the TETA 4HCl formulation provided more rapid absorption of trientine and greater systemic exposure in healthy subjects. Clinical Trials Number EudraCT # 2015-002199-25.

Modulation of Intracellular Copper Levels as the Mechanism of Action of Anticancer Copper Complexes: Clinical Relevance

Copper (Cu) is a vital element required for cellular growth and development; however, even slight changes in its homeostasis might lead to severe toxicity and deleterious medical conditions. Cancer patients are typically associated with higher Cu content in serum and tumor tissues, indicating increased demand of cancer cells for this micronutrient. Cu is known to readily cycle between the +1 and +2 oxidation state in biological systems. The mechanism of action of Cu complexes is typically based on their redox activity and induction of reactive oxygen species (ROS), leading to deadly oxidative stress. However, there are a number of other biomolecular mechanisms beyond ROS generation that contribute to the activity of anticancer Cu drug candidates. In this review, we discuss how interfering with intracellular Cu balance via either diet modification or addition of inorganic Cu supplements or Cu-modulating compounds affects tumor development, progression, and sensitivity to treatment modalities. We aim to provide the rationale for the use of Cu-depleting and Cu-overloading conditions to generate the best possible patient outcome with minimal toxicity. We also discuss the advantages of the use of pre-formed Cu complexes, such as Cu-(bis)thiosemicarbazones or Cu-N-heterocyclic thiosemicarbazones, in comparison with the in situ formed Cu complexes with metal-binding ligands. In this review, we summarize available clinical and mechanistic data on clinically relevant anticancer drug candidates, including Cu supplements, Cu chelators, Cu ionophores, and Cu complexes.

Enhancement of NO release from S-nitrosoalbumin by pollution derived metal ions

S-Nitrosothiols act as a comparatively long-lived reservoir of releasable nitric oxide (NO) present in vivo in a variety of body fluids. Soluble constituents of air-borne particulate matter (PM) can affect S-nitrosothiol stability and deregulate NO-based biological signaling. PM aqueous extracts of standard urban dust (SRM 1648a) were prepared, and their effect on human serum S-nitrosoalbumin (HSA-NO) stability was studied. The results indicated that PM extracts induced a release of NO from HSA-NO in a dose-dependent manner. To identify the inorganic components of urban PM responsible for HSA-NO decomposition, the effects of individual metal ions and metal ion mixtures, detected in the SRM 1648a aqueous extract, were examined. The dominant role of copper ions (specifically Cu+) was confirmed, but the results did not exclude the influence of other water-soluble PM components. Measurements with the application of several common metal ion chelators confirmed that Cu2+ may participate in NO release from HSA-NO and that reduction to monovalent Cu+ (responsible for S-NO bond breaking) may occur with the participation of S-nitrosoalbumin. The addition of ascorbic acid (AscA) significantly enhanced the effectiveness of NO release by PM extracts both kinetically and quantitatively, by inducing an increase in the reduction of Cu2+ to Cu+. These results indicate that AscA present in the respiratory tract lining fluids and plasma may amplify the activity of inorganic components of PM in S-nitrosothiol decomposition.

Copper: An Intracellular Achilles' Heel Allowing the Targeting of Epigenetics, Kinase Pathways, and Cell Metabolism in Cancer Therapeutics

Copper is an essential transition metal frequently increased in cancer known to strongly influence essential cellular processes. Targeted therapy protocols utilizing both novel and repurposed drug agents initially demonstrate strong efficacy, before failing in advanced cancers as drug resistance develops and relapse occurs. Overcoming this limitation involves the development of strategies and protocols aimed at a wider targeting of the underlying molecular changes. Receptor Tyrosine Kinase signaling pathways, epigenetic mechanisms and cell metabolism are among the most common therapeutic targets, with molecular investigations increasingly demonstrating the strong influence each mechanism exerts on the others. Interestingly, all these mechanisms can be influenced by intracellular copper. We propose that copper chelating agents, already in clinical trial for multiple cancers, may simultaneously target these mechanisms across a wide variety of cancers, serving as an excellent candidate for targeted combination therapy. This review summarizes the known links between these mechanisms, copper, and copper chelation therapy.

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.

LC-MS proteomic profiling of Caco-2 human intestinal cells exposed to the copper-chelating agent, triethylenetetramine: A preliminary study

Homeostasis of metal micronutrients such as copper is tightly regulated to ensure deficiency does not occur while restricting damage resulting from excess accumulation. Using LC-MS the effect on the proteome of intestinal Caco-2 cells of exposure to the chelator triethylenetetramine (TETA) was investigated. Continuous exposure of TETA at 25 μM to Caco-2 cells caused decreased cell yields and morphological changes. These effects were reversed when cells were no longer exposed to TETA. Quantitative proteomic analysis identified 957 mostly low-fold differentially expressed proteins, 41 of these returned towards control Caco-2 expression following recovery. Proteins exhibiting this "reciprocal" behaviour included upregulated deoxyhypusine hydroxylase (DOHH, 15.69- fold), a protein essential for eIF-5A factor hypsuination, a post translational modification responsible for eIF-5A maturation, which in turn is responsible for translation elongation. Exposure to TETA also resulted in 87 proteins, the expression of which was stable and remained differentially expressed following recovery. This study helps to elucidate the stable and transient proteomic effects of TETA exposure in intestinal cells.

Current Biomedical Use of Copper Chelation Therapy

Copper is an essential microelement that plays an important role in a wide variety of biological processes. Copper concentration has to be finely regulated, as any imbalance in its homeostasis can induce abnormalities. In particular, excess copper plays an important role in the etiopathogenesis of the genetic disease Wilson's syndrome, in neurological and neurodegenerative pathologies such as Alzheimer's and Parkinson's diseases, in idiopathic pulmonary fibrosis, in diabetes, and in several forms of cancer. Copper chelating agents are among the most promising tools to keep copper concentration at physiological levels. In this review, we focus on the most relevant compounds experimentally and clinically evaluated for their ability to counteract copper homeostasis deregulation. In particular, we provide a general overview of the main disorders characterized by a pathological increase in copper levels, summarizing the principal copper chelating therapies adopted in clinical trials.

Characterisation and proteomic profiling of continuously exposed Cu-resistant variants of the Caco-2 cell line

Studies in hepatic systems identify multiple factors involved in the generation of copper resistance. As the intestine is the route of exposure to dietary copper, we wanted to understand how intestinal cells overcome the toxic effects of high copper and what mechanisms of resistance develop. Using the intestinal cell line Caco-2, resistance was developed by serial subculture in 50 μM copper in inorganic (CuSO₄) or organic (Cu proteinate) forms. Caco-2 variants exhibited resistance to copper and retained the non-monotonic dose response while displaying stable phenotypes following repeated subculture in the absence of copper. Phenotypic changes on exposure to copper in parental Caco-2 cells included significantly increased total protein yield, ROS, SOD, metallothionein expression, GSH and total glutathione. These phenotypic changes were not replicated in resistant variants on a per cell basis. Quantitative label-free LC-MS/MS proteomic analysis identified 1113 differentially expressed proteins (DEPs) between parental Caco-2 and resistant cells. With some exceptions, most of the DEPs were overexpressed to a low level around 2-fold suggesting resistance was supported by multiple small changes in protein expression. These variants may be a useful tool in studying the toxicity of stress responses in further Cu-related studies.

Octahedral copper(ii)-diimine complexes of triethylenetetramine: effect of stereochemical fluxionality and ligand hydrophobicity on CuII/CuIredox, DNA binding and cleavage, cytotoxicity and apoptosis-inducing ability

Stereochemical fluxionality of octahedral [Cu(trien)(diimine)]²⁺complexes determines the Cu^II/Cu^Iredox potential, DNA binding affinity, ROS generation, cytotoxicity and apoptosis-inducing ability.

Trientine-induced Rhabdomyolysis in an Adolescent with Wilson\'s Disease

Background

Drugs are very important in the etiology of nontraumatic rhabdomyolysis.

Case descriptions

A 16-year-old male patient with Wilson's disease was admitted for myoclonic contractions. Oral trientine was started for neurological problems and tremor on the hands due to D-penicillamine 1 month ago. Patient was oligoanuric, and his creatine kinase level was 15197 U/L. Rhabdomyolysis was associated with trientine, and trientine treatment was stopped. Hemodiafiltration was performed. The patient began to urinate on the 24th day.

Conclusion

This is the first pediatric patient with rhabdomyolysis induced by trientine. Drugs used should be questioned carefully in patients with rhabdomyolysis.

How to cite this article

Aslan N, Yavuz S, Yildizdas D, Horoz OO, Coban Y, Tumgor G, et al. Trientine-induced Rhabdomyolysis in an Adolescent with Wilson's Disease. Indian J Crit Care Med 2019;23(10):489–490.

A Dose Escalation Study of Trientine Plus Carboplatin and Pegylated Liposomal Doxorubicin in Women With a First Relapse of Epithelial Ovarian, Tubal, and Peritoneal Cancer Within 12 Months After Platinum-Based Chemotherapy

Background: Epithelial ovarian cancer (EOC) is the leading cause of gynecological cancer-related deaths worldwide. Preclinical studies found that copper-lowering agents could re-sensitize platinum-resistant cancer cells by enhancing the human copper transporter 1 (hCtr1)-mediated uptake of platinum. In the clinic, re-sensitization of platinum-resistance in relapsed EOC has been discovered by the application of trientine plus platinum (NCT01178112). However, no pharmacokinetic data of trientine has been reported in cancer patients.

Purpose: Our study aimed to explore the safety and activity of trientine combined with carboplatin and pegylated liposomal doxorubicin (PLD) in patients with EOC, tubal, and peritoneal cancer who experienced disease progression during platinum-based chemotherapy or showed relapse <12 months after completing first-line chemotherapy. Also, we aimed to demonstrate pharmacokinetic parameters and to discover potential biomarkers in our EOC patients.

Methods: In this dose escalation study, 18 Asian patients in six dosing cohorts received fixed doses of carboplatin (AUC 4) and PLD (LipoDox®, TTY Biopharm Co. Ltd., Taipei, Taiwan) (40 mg/m², day 1 per 4-week cycle), and escalated daily trientine doses (range: 300–1800 mg; initiated 7 days before the 1st combination cycle) according to a 3 + 3 design.

Results: No dose-limiting toxicity or treatment-related death was observed. Four patients (22.2%) developed grade 3 drug-related adverse events (AEs), whereas no grade 4 AEs were encountered. Anemia and grade 2 dizziness were the most common hematological toxicity and neurotoxicity, respectively. In a pharmacokinetics comparison with healthy volunteers in the literature, our patients achieved greater absorption after oral trientinem, and more rapid elimination of triethylenetetramine dihydrochloride at high doses. The clinical benefit rate was 33.3 and 50.0% in the platinum-resistant and the partially platinum-sensitive group, respectively. A high baseline serum iron level and low serum copper level might help differentiate subgroups of patients with different clinical responses. Nevertheless, no associations of the clinical response with the levels of serum hCtr1, ceruloplasmin, or copper were observed.

Conclusion: Combination therapy with carboplatin, trientine, and PLD was well-tolerated and safe. Our results encourage the development of a future phase II trial.

Clinical trial registration:ClinicalTrials.gov # NCT03480750.

Solvent engineering based on triethylenetetramine (TETA) for perovskite solar cells processed in ambient-air

Solvent engineering as a crucial factor in determining the photovoltaic performance of perovskite solar cells has attracted much attention in recent years. Herein, we treat PbI2 and perovskite films with isopropyl alcohol, acetone, diethyl ether and dichloromethane, as standard solvents, in a modified two-step method. Meanwhile, triethylenetetramine (TETA) is introduced as a new reagent in solvent engineering for perovskite solar cell devices. Structural, optical and photovoltaic characteristics of the TETA-treated perovskite films are compared with those of the ones treated with different solvents. A shiny, pinhole-free and full-coverage texture with sufficiently large grain sizes is obtained in the presence of TETA, suggesting an efficient solvent engineering for perovskite layers. Moreover, the results reveal that residual PbI2 is completely removed and converted to a crystalline perovskite film. Amongst the PSC devices engineered with various solvents, the TETA-treated film exhibits a 55% increase in photoconversion efficiency compared to the control device with no solvent engineering.

A human vision inspired adaptive platform for one-on-multiple recognition

The fluorescence of a coordinative molecule DCM displaying an intramolecular charge transfer (ICT) effect is regulated by several metal ions. These DCM-metal complexes were adopted to recognize different chemicals, including the recognition of triethylenetetramine, thiol-containing amino acids, and H2S upon binding DCM with Zn2+, Ag+, and Pb2+, respectively. This is in analogy to the general mode of human trichromatic color vision.

Chelating principles in Menkes and Wilson diseases: Choosing the right compounds in the right combinations at the right time

Dysregulation of copper homeostasis in humans is primarily found in two genetic diseases of copper transport, Menkes and Wilson diseases, which show symptoms of copper deficiency or overload, respectively. However, both diseases are copper storage disorders despite completely opposite clinical pictures. Clinically, Menkes disease is characterized by copper deficiency secondary to poor loading of copper-requiring enzymes although sufficient body copper. Copper accumulates in non-hepatic tissues, but is deficient in blood, liver, and brain. In contrast, Wilson disease is characterized by symptoms of copper toxicity secondary to accumulation of copper in several organs most notably brain and liver, and a saturated blood copper pool. It is a challenge to correct copper dyshomeostasis in either disease though copper depletion in Menkes disease is most challenging. Both diseases are caused by defective copper export from distinct cells, and we seek to give new angles and guidelines to improve treatment of these two complementary diseases. Therapy of Menkes disease with copper-histidine, thiocarbamate, nitrilotriacetate or lipoic acid is discussed. In Wilson disease combination of a hydrophilic chelator e.g. trientine or dimercaptosuccinate with a brain shuttle e.g. thiomolybdate or lipoate, is discussed. New chelating principles for copper removal or delivery are outlined.

A Perspective - can copper complexes be developed as a novel class of therapeutics?

Although copper-ligand complexes appear to be promising as a new class of therapeutics, other than the family of copper(ii) coordination compounds referred to as casiopeínas these compounds have yet to reach the clinic for human use. The pharmaceutical challenges associated with developing copper-based therapeutics will be presented in this article along with a discussion of the potential for high-throughput chemistry, computer-aided drug design, and nanotechnology to address the development of this important class of drug candidates.

DPM-1001 decreased copper levels and ameliorated deficits in a mouse model of Wilson's disease

In this study, Krishnan et al. present the characterization of DPM-1001 as a potent and highly selective chelator of copper that is orally bioavailable. Treatment of the toxic milk mouse model of Wilson's disease with DPM-1001 lowered the levels of copper in the liver and brain, removing excess copper by excretion in the feces while ameliorating symptoms associated with the disease, suggesting that DPM-1001 should be investigated further as a new therapeutic agent for the treatment of Wilson's disease.

The levels of copper, which is an essential element in living organisms, are under tight homeostatic control. Inactivating mutations in ATP7B, a P-type Cu-ATPase that functions in copper excretion, promote aberrant accumulation of the metal, primarily the in liver and brain. This condition underlies Wilson's disease, a severe autosomal recessive disorder characterized by profound hepatic and neurological deficits. Current treatment regimens rely on the use of broad specificity metal chelators as “decoppering” agents; however, there are side effects that limit their effectiveness. Here, we present the characterization of DPM-1001 {methyl 4-[7-hydroxy-10,13-dimethyl-3-({4-[(pyridin-2-ylmethyl)amino]butyl}amino)hexadecahydro-1H-cyclopenta[a]phenanthren-17-yl] pentanoate} as a potent and highly selective chelator of copper that is orally bioavailable. Treatment of cell models, including fibroblasts derived from Wilson's disease patients, eliminated adverse effects associated with copper accumulation. Furthermore, treatment of the toxic milk mouse model of Wilson's disease with DPM-1001 lowered the levels of copper in the liver and brain, removing excess copper by excretion in the feces while ameliorating symptoms associated with the disease. These data suggest that it may be worthwhile to investigate DPM-1001 further as a new therapeutic agent for the treatment of Wilson's disease, with potential for application in other indications associated with elevated copper, including cancer and neurodegenerative diseases.

Biodegradation of CuTETA, an effluent by-product in mineral processing

Polyamines such as triethylenetetramine (TETA) and other amine chelators are used in mineral processing applications. Formation of heavy metal complexes of these reagents as a by-product in effluent water is a recent environmental concern. In this study, Paecilomyces sp. was enriched from soil on TETA as the sole source of carbon and nitrogen and was found to degrade > 96 and 90% CuTETA complexes at initial concentrations of 0.32 and 0.79 mM respectively, following 96-h incubation. After destabilization, most of the copper (> 78%) was complexed extracellularly and the rest was associated with the cell. Mass spectroscopy results provided confirmation that copper re-complexed with small, extracellular, and organic molecules. There are no reports in the literature that Paecilomyces or any other organism can grow on TETA or CuTETA. This study is the first to show that biological destabilization of CuTETA complexes in mineral processing effluents is feasible.

Copper-Binding Small Molecule Induces Oxidative Stress and Cell-Cycle Arrest in Glioblastoma-Patient-Derived Cells

Transition metals are essential, but deregulation of their metabolism causes toxicity. Here, we report that the compound NSC319726 binds copper to induce oxidative stress and arrest glioblastoma-patient-derived cells at picomolar concentrations. Pharmacogenomic analysis suggested that NSC319726 and 65 other structural analogs exhibit lethality through metal binding. Although NSC319726 has been reported to function as a zinc ionophore, we report here that this compound binds to copper to arrest cell growth. We generated and validated pharmacogenomic predictions: copper toxicity was substantially inhibited by hypoxia, through an hypoxia-inducible-factor-1α-dependent pathway; copper-bound NSC319726 induced the generation of reactive oxygen species and depletion of deoxyribosyl purines, resulting in cell-cycle arrest. These results suggest that metal-induced DNA damage may be a consequence of exposure to some xenobiotics, therapeutic agents, as well as other causes of copper dysregulation, and reveal a potent mechanism for targeting glioblastomas.

Triethylenetetramine Synergizes with Pharmacologic Ascorbic Acid in Hydrogen Peroxide Mediated Selective Toxicity to Breast Cancer Cell

Breast cancer is characterized by overexpression of superoxide dismutase (SOD) and downregulation of catalase and more resistance to hydrogen peroxide (H₂O₂) than normal cells. Thus, relatively high H₂O₂ promotes breast cancer cell growth and proliferation. However, excessive intracellular H₂O₂ leads to death of breast cancer cells. In cancer cells, high level ascorbic acid (Asc) is able to be autoxidized and thus provides an electron to oxygen to generate H₂O₂. In the present study, we demonstrated that triethylenetetramine (TETA) enhances Asc autoxidation and thus elevates H₂O₂ production in MCF-7 cells. Furthermore, Asc/TETA combination significantly impaired cancer cell viability, while having much milder effects on normal cells, indicating Asc/TETA could be a promising therapy for breast cancer. Moreover, SOD1 and N-acetyl-L-cysteine failed to improve MCF-7 cells viability in the presence of Asc/TETA, while catalase significantly inhibited the cytotoxicity of Asc/TETA to breast cancer cells, strongly suggesting that the selective cytotoxicity of Asc/TETA to cancer cells is H₂O₂-dependent. In addition, Asc/TETA induces RAS/ERK downregulation in breast cancer cells. Animal studies confirmed that Asc/TETA effectively suppressed tumor growth in vivo. In conclusion, TETA synergizes pharmacologic Asc autoxidation and H₂O₂ overproduction in breast cancer cells, which suppresses RAS/ERK pathway and results in apoptosis.

Triethylenetetramine modulates polyamine and energy metabolism and inhibits cancer cell proliferation

Copper chelators show anticancer effects by preventing neo-angiogenesis. In the present study, we show that triethylenetetramine (TETA) is a multi-targeting drug, which modulates several key regulatory proteins of polyamine metabolism that contributes to its anticancer effect.

A case of Trientine Overdose

Wilson disease is a rare genetic hepatic and neurological disorder of copper accumulation. Trientine is usually used as a second line in the management of patients with this condition. We present a case of a large overdose of Trientine (60 g) resulting in self-limiting dizziness and vomiting with no further clinical sequelae or significant biochemical abnormalities. This case shows that Trientine has a good safety profile and hence could be used as a first line treatment in patients with Wilson's disease who suffer from psychiatric complications and who might be at risk of self-harm.

A novel enzyme with spermine oxidase properties in bovine liver mitochondria: identification and kinetic characterization

The uptake of spermine into mammalian mitochondria indicated the need to identify its catabolic pathway in these organelles. Bovine liver mitochondria were therefore purified and their capacity for natural polyamine uptake was verified. A kinetic approach was then used to determine the presence of an MDL 72527-sensitive enzyme with spermine oxidase activity in the matrix of bovine liver mitochondria. Western blot analysis of mitochondrial fractions and immunogold electron microscopy observations of purified mitochondria unequivocally confirmed the presence of a protein recognized by anti-spermine oxidase antibodies in the mitochondrial matrix. Preliminary kinetic characterization showed that spermine is the preferred substrate of this enzyme; lower activity was detected with spermidine and acetylated polyamines. Catalytic efficiency comparable to that of spermine was also found for 1-aminododecane. The considerable effect of ionic strength on the Vmax/KM ratio suggested the presence of more than one negatively charged zone inside the active site cavity of this mitochondrial enzyme, which is probably involved in the docking of positively charged substrates. These findings indicate that the bovine liver mitochondrial matrix contains an enzyme belonging to the spermine oxidase class. Because H2O2 is generated by spermine oxidase activity, the possible involvement of the latter as an important signaling transducer under both physiological and pathological conditions should be considered.

Chelation in metal intoxication--Principles and paradigms

The present review provides an update of the general principles for the investigation and use of chelating agents in the treatment of intoxications by metals. The clinical use of the old chelators EDTA (ethylenediamine tetraacetate) and BAL (2,3-dimercaptopropanol) is now limited due to the inconvenience of parenteral administration, their own toxicity and tendency to increase the neurotoxicity of several metals. The hydrophilic dithiol chelators DMSA (meso-2,3-dimercaptosuccinic acid) and DMPS (2,3-dimercapto-propanesulphonate) are less toxic and more efficient than BAL in the clinical treatment of heavy metal poisoning, and available as capsules for oral use. In copper overload, DMSA appears to be a potent antidote, although d-penicillamine is still widely used. In the chelation of iron, the thiols are inefficient, since iron has higher affinity for ligands with nitrogen and oxygen, but the new oral iron antidotes deferiprone and desferasirox have entered into the clinical arena. Comparisons of these agents and deferoxamine infusions are in progress. General principles for research and development of new chelators are briefly outlined in this review.

Exploratory study of carboplatin plus the copper-lowering agent trientine in patients with advanced malignancies

PURPOSE

Preclinical data showed that trientine, a copper-lowering agent, re-sensitized cancer cells to carboplatin through enhanced human copper transporter 1 (hCtr1) -mediated platinum uptake.

EXPERIMENTAL DESIGN

We studied carboplatin and trientine in patients (n = 55; 45 who had failed platinum) with advanced malignancies (Phase I, modified 3 + 3 design).

RESULTS

The most common cancers were head and neck (n = 13), non-small cell lung (n = 10) and epithelial ovarian (n = 8). The median number of prior regimens was four. No dose-limiting toxicity or treatment-related deaths were observed at doses up to carboplatin AUC 6 given with trientine. Eight patients achieved stable disease (SD) ≥ 6 months (six platinum failures) and one patient with platinum-resistant ovarian cancer, partial response (PR) (total SD ≥ 6 months/PR = 9, 16.4 %). The mean nadir serum copper level in the nine patients with SD ≥ 6 months/PR was 0.55 μg/mL (95 % CI, 0.34-0.75) versus 1.22 μg/mL (95 % CI, 1.02-1.42) (p < 0.001) in 38 tested patients with progression. In patients who maintained their ceruloplasmin (major copper-carrying protein) levels at 5-15 mg/dL (n = 9), the median progression-free and overall survivals were 9.2 and 15.2 months versus 1.9 (p = 0.001) and 5.7 months (p = 0.033) in patients who did not (n = 38), respectively.

CONCLUSIONS

The combination of a copper-lowering agent with carboplatin was well tolerated and associated with antitumor activity, especially in patients in whom copper and/or ceruloplasmin levels were lowered. Further investigation of this strategy for reversing platinum resistance is warranted.

Molecular strategies to prevent, inhibit, and degrade advanced glycoxidation and advanced lipoxidation end products

The advanced glycoxidation end products (AGEs) and lipoxidation end products (ALEs) contribute to the development of diabetic complications and of other pathologies. The review discusses the possibilities of counteracting the formation and stimulating the degradation of these species by pharmaceuticals and natural compounds. The review discusses inhibitors of ALE and AGE formation, cross-link breakers, ALE/AGE elimination by enzymes and proteolytic systems, receptors for advanced glycation end products (RAGEs) and blockade of the ligand-RAGE axis.

The treatment of Wilson's disease, a rare genetic disorder of copper metabolism

Wilson's disease is a rare autosomal recessive disease characterised by the deposition of copper in the brain, liver; cornea, and other organs. The overload of copper inevitably leads to progressive liver and neurological dysfunction. Copper overload in patients with Wilson's disease is caused by impairment to the biliary route for excretion of dietary copper A combination of neurological, psychiatric and hepatic symptoms can make the diagnosis of Wilson's disease challenging. Most symptoms appear in the second and third decades of life. The disease affects between one in 30,000 and one in 100,000 individuals, and is fatal if left untreated. Five drugs are currently available to treat Wilson's disease: British Anti-Lewisite; D-penicillamine; trientine; zinc sulfate or acetate; and ammonium tetrathiomolybdate. Each drug can reduce copper levels and/or transform copper into a metabolically inert and unavailable form in the patient. The discovery and introduction of these five drugs owes more to the inspiration of a few dedicated physicians and agricultural scientists than to the resources of the pharmaceutical industry.

Metabolomic analysis of rat serum in streptozotocin-induced diabetes and after treatment with oral triethylenetetramine (TETA)

Background

The prevalence, and associated healthcare burden, of diabetes mellitus is increasing worldwide. Mortality and morbidity are associated with diabetic complications in multiple organs and tissues, including the eye, kidney and cardiovascular system, and new therapeutics to treat these complications are required urgently. Triethylenetetramine (TETA) is one such experimental therapeutic that acts to chelate excess copper (II) in diabetic tissues and reduce oxidative stress and cellular damage.

Methods

Here we have performed two independent metabolomic studies of serum to assess the suitability of the streptozotocin (STZ)-induced rat model for studying diabetes and to define metabolite-related changes associated with TETA treatment. Ultraperformance liquid chromatography-mass spectrometry studies of serum from non-diabetic/untreated, non-diabetic/TETA-treated, STZ-induced diabetic/untreated and STZ-induced diabetic/TETA-treated rats were performed followed by univariate and multivariate analysis of data.

Results

Multiple metabolic changes related to STZ-induced diabetes, some of which have been reported previously in other animal and human studies, were observed, including changes in amino acid, fatty acid, glycerophospholipid and bile acid metabolism. Correlation analysis suggested that treatment with TETA led to a reversal of diabetes-associated changes in bile acid, fatty acid, steroid, sphingolipid and glycerophospholipid metabolism and proteolysis.

Conclusions

Metabolomic studies have shown that the STZ-induced rat model of diabetes is an appropriate model system to undertake research into diabetes and potential therapies as several metabolic changes observed in humans and other animal models were also observed in this study. Metabolomics has also identified several biological processes and metabolic pathways implicated in diabetic complications and reversed following treatment with the experimental therapeutic TETA.

Overcoming platinum resistance through the use of a copper-lowering agent

Low levels of human copper transporter 1 (hCtr1) mRNA are associated with a shorter progression-free survival after platinum-based therapy. Pretreatment with a copper-lowering agent such as trientine enhanced hCtr1-mediated platinum uptake. Therefore, we conducted a pilot study (NCT01178112) of carboplatin and trientine with the goal of resensitizing patients with advanced cancer to platinum chemotherapy. This case report reviews the outcomes of 5 patients with platinum-resistant high-grade epithelial ovarian cancer enrolled on the study to date. Overall, they tolerated treatment well. Severe adverse events that occurred in 2 patients were myelosuppression, notably anemia requiring transfusion. Dose-limiting toxicity was not observed within the first 28 days (cycle 1). After 2 cycles of therapy, partial remission was achieved in 1 patient (10+ months), stable disease in 3 patients (2, 3.5+, and 5 months, respectively), and 1 patient had progressive disease. These cases provide preliminary clinical evidence that the role of decreasing copper levels in reversing platinum resistance merits additional clinical investigation. Evaluation of this novel strategy is warranted in larger studies to assess the efficacy of this approach for treating platinum-resistant advanced epithelial ovarian cancer in patients with high copper levels.

Complex N-acetylation of triethylenetetramine

Triethylenetetramine (TETA) is an efficient copper chelator that has versatile clinical potential. We have recently shown that spermidine/spermine-N(1)-acetyltransferase (SSAT1), the key polyamine catabolic enzyme, acetylates TETA in vitro. Here, we studied the metabolism of TETA in three different mouse lines: syngenic, SSAT1-overexpressing, and SSAT1-deficient (SSAT1-KO) mice. The mice were sacrificed at 1, 2, or 4 h after TETA injection (300 mg/kg i.p.). We found only N(1)-acetyltriethylenetetramine (N(1)AcTETA) and/or TETA in the liver, kidney, and plasma samples. As expected, SSAT1-overexpressing mice acetylated TETA at an accelerated rate compared with syngenic and SSAT1-KO mice. It is noteworthy that SSAT1-KO mice metabolized TETA as syngenic mice did, probably by thialysine acetyltransferase, which had a K(m) value of 2.5 ± 0.3 mM and a k(cat) value of 1.3 s(-1) for TETA when tested in vitro with the human recombinant enzyme. Thus, the present results suggest that there are at least two N-acetylases potentially metabolizing TETA. However, their physiological significance for TETA acetylation requires further studies. Furthermore, we detected chemical intramolecular N-acetyl migration from the N(1) to N(3) position of N(1)AcTETA and N(1),N(8)-diacetyltriethylenetetramine in an acidified high-performance liquid chromatography sample matrix. The complex metabolism of TETA together with the intramolecular N-acetyl migration may explain the huge individual variations in the acetylation rate of TETA reported earlier.

Enhancement of cyclophosphamide-induced antitumor effect by a novel polysaccharide from Ganoderma atrum in sarcoma 180-bearing mice

The aim of this study was to investigate the enhancement of Ganoderma atrum polysaccharide (PSG-1) on cyclophosphamide (CTX)-induced antitumor effect in sarcoma 180 (S-180)-bearing mice. Results showed that both CTX and PSG-1 delayed tumor growth and resulted in tumor apoptosis. The combined regimen was superior to either modality alone. Moreover, the combined treatment-induced apoptosis was mediated via mitochondrial pathway, as evidenced by alterations of Bcl-2 family proteins, loss of mitochondrial membrane potential (Δψ(m)), cytochrome c release, and caspases activation. Our results also showed that thymus and spleen indexes, lymphocytes proliferation, and concentrations of cytokine in the CTX group were decreased, which were alleviated by PSG-1. Additionally, the combined treatment ameliorated oxidative stress as compared with CTX alone. Taken together, we conclude that PSG-1 improved the antitumor effect of CTX, possibly in part mediated by enhancing the induction of apoptosis via mitochondrial pathways, activating host immune function, and modifying the redox system in S-180-bearing mice.

The adaptive stroma joining the antiangiogenic resistance front

Resistance to antiangiogenic therapies in cancer involves both tumor cells and stromal components, but their relative contributions differ in each cancer subtype. In this issue of the JCI, Cascone et al. describe a stromal adaptation to antiangiogenic therapy in non-small cell lung carcinoma (NSCLC) models that include EGFR-driven vascular remodeling promoting resistance to VEGF inhibition. Their results suggest that the added benefit of dual VEGF/R and EGFR targeting in these models could be clinically relevant to fight resistance in NSCLC patients.