Molecular mechanisms underlying copper homeostasis in Mammalian cells

Involvement of the inhibition of mitochondrial apoptotic, p53, NF-κB pathways and the activation of Nrf2/HO-1 pathway in the protective effects of curcumin against copper sulfate-induced nephrotoxicity in mice

Chronic copper exposure could cause potential nephrotoxicity and effective therapy strategies are limited. This study investigated the protective effects of curcumin on copper sulfate (CuSO4)-induced renal damage in a mouse model and the underlying molecular mechanisms. Mice were administrated orally with CuSO4 (100 mg/kg per day) in combination with or without curcumin (50, 100 or 200 mg/kg per day, orally) for 28 days. Results showed that curcumin supplementation significantly reduce the Cu accumulation in the kidney tissues of mice and improved CuSO4-induced renal dysfunction. Furthermore, curcumin supplantation also significantly ameliorated Cu exposure-induced oxidative stress and tubular necrosis in the kidneys of mice. Moreover, compared to the CuSO4 alone group, curcumin supplementation at 200 mg/kg per day significantly decreased CuSO4-induced the expression of p53, Bax, IL-1β, IL-6, and TNF-α proteins, levels of NF-κB mRNA, levels of caspases-9 and - 3 activities, and cell apoptosis, and significantly increased the levels of Nrf2 and HO-1 mRNAs in the kidney tissues. In conclusion, for the first time, our results reveal that curcumin could trigger the inhibition of oxidative stress, mitochondrial apoptotic, p53, and NF-κB pathways and the activation of Nrf2/HO-1 pathway to ameliorate Cu overload-induced nephrotoxicity in a mouse model. Our study highlights that curcumin supplementation may be a promising treatment strategy for treating copper overload-caused nephrotoxicity.

Cinnamon Extract and Probiotic Supplementation Alleviate Copper-Induced Nephrotoxicity via Modulating Oxidative Stress, Inflammation, and Apoptosis in Broiler Chickens

The present study aimed to assess the potential protective effects of cinnamon (Cinnamomum zeylanicum, Cin) and probiotic against CuSO₄-induced nephrotoxicity in broiler chickens. One-day-old Cobb chicks were assigned into seven groups (15 birds/group): control group, fed basal diet; Cin group, fed the basal diet mixed with Cin (200 mg/kg); PR group, receiving PR (1 g/4 L water); Cu group, fed the basal diets mixed with CuSO₄ (300 mg/kg); Cu + Cin group; Cu + PR group; and Cu + Cin + PR group. All treatments were given daily for 6 weeks. Treatment of Cu-intoxicated chickens with Cin and/or PR reduced (p < 0.05) Cu contents in renal tissues and serum levels of urea, creatinine, and uric acid compared to the Cu group. Moreover, Cin and PR treatment decreased lipid peroxidation and increased antioxidant enzyme activities in chickens' kidney. Additionally, significant reduction (p < 0.05) in the mRNA expression of tumor necrosis factor alpha (TNF-α), interleukin (IL-2) and Bax, and in cyclooxygenase (COX-II) enzyme expression, and significant elevation (p < 0.05) in mRNA expression of IL-10 and Bcl-2 were observed in kidneys of Cu + Cin, Cu + PR, and Cu + Cin + PR groups compared to Cu group. Conclusively, Cin and/or PR afford considerable renal protection against Cu-induced nephrotoxicity in chickens.

Molecular Insights of Copper Sulfate Exposure-Induced Nephrotoxicity: Involvement of Oxidative and Endoplasmic Reticulum Stress Pathways

The precise pathogenic mechanism in Cu exposure-cause nephrotoxicity remains unclear. This study investigated the underlying molecular mechanism of copper sulfate (CuSO₄)-induced nephrotoxicity. Mice were treated with CuSO₄ at 50, 100, 200 mg/kg/day or co-treated with CuSO₄ (200 mg/kg/day) and 4-phenylbutyric acid (4-PBA, 100 mg/kg/day) for 28 consecutive days. HEK293 cells were treated with CuSO₄ (400 μM) with or without superoxide dismutase, catalase or 4-PBA for 24 h. Results showed that CuSO₄ exposure can cause renal dysfunction and tubular necrosis in the kidney tissues of mice. CuSO₄ exposure up-regulated the activities and mRNA expression of caspases-9 and -3 as well as the expression of glucose-regulated protein 78 (GRP78), GRP94, DNA damage-inducible gene 153 (GADD153/CHOP), caspase-12 mRNAs in the kidney tissues. Furthermore, superoxide dismutase and catalase pre-treatments partly inhibited CuSO₄-induced cytotoxicity by decreasing reactive oxygen species (ROS) production, activities of caspases-9 and -3 and DNA fragmentations in HEK293 cells. 4-PBA co-treatment significantly improved CuSO₄-induced cytotoxicity in HEK293 cells and inhibited CuSO₄ exposure-induced renal dysfunction and pathology damage in the kidney tissues. In conclusion, our results reveal that oxidative stress and endoplasmic reticulum stress contribute to CuSO₄-induced nephrotoxicity. Our study highlights that targeting endoplasmic reticulum and oxidative stress may offer an approach for Cu overload-caused nephrotoxicity.

Exploring the Extended Biological Functions of the Human Copper Chaperone of Superoxide Dismutase 1

The human copper chaperone of SOD1 (designated as CCS) was discovered more than two decades ago. It is an important copper binding protein and a homolog of Saccharomyces cerevisiae LYS7. To date, no studies have systematically or specifically elaborated on the functional development of CCS. This review summarizes the essential information about CCS, such as its localization, 3D structure, and copper binding ability. An emphasis is placed on its interacting protein partners and its biological functions in vivo and in vitro. Three-dimensional structural analysis revealed that CCS is composed of three domains. Its primary molecular function is the delivery of copper to SOD1 and activation of SOD1. It has also been reported to bind to XIAP, Mia40, and X11α, and other proteins. Through these protein partners, CCS is implicated in several vital biological processes in vivo, such as copper homeostasis, apoptosis, angiogenesis and oxidative stress. This review is anticipated to assist scientists in systematically understanding the latest research developments of CCS for facilitating the development of new therapeutics targeting CCS in the future.

Minerals in thalassaemia major patients: An overview

Thalassaemia major (TM) is a hereditary blood disease characterised by reduced or absent production of beta globin chains. Erythrocyte transfusions are given to raise the haemoglobin level in patients with thalassaemia major. However, transfusions have been related to increased risk of iron overload and tissue damage related to excess iron. Both elevated oxidative stress due to iron overload and increased hemolysis lead to over utilisation of minerals required for antioxidant enzymes activities. Iron chelators have been used to prevent iron overload in thalassaemia major patients, but these chelators have the possibility of removing minerals from the body. Thalassaemia patients are more at risk for mineral deficiency because of increased oxidative stress and iron chelation therapies. Growth and maturational delay, cardiomyopathy, endocrinopathies and osteoporosis are the complications of thalassaemia. Minerals may play a particular role to prevent these complications. In the current review, we provide an overview of minerals including zinc (Zn), copper (Cu), selenium (Se), magnesium (Mg) and calcium (Ca) in thalassaemia major patients. We, also, underline that some complications of thalassaemia can be caused by an increased need for minerals or lack of the minerals.

Screening of a composite library of clinically used drugs and well-characterized pharmacological compounds for cystathionine β-synthase inhibition identifies benserazide as a drug potentially suitable for repurposing for the experimental therapy of colon cancer

Cystathionine-β-synthase (CBS) has been recently identified as a drug target for several forms of cancer. Currently no potent and selective CBS inhibitors are available. Using a composite collection of 8871 clinically used drugs and well-annotated pharmacological compounds (including the LOPAC library, the FDA Approved Drug Library, the NIH Clinical Collection, the New Prestwick Chemical Library, the US Drug Collection, the International Drug Collection, the ‘Killer Plates’ collection and a small custom collection of PLP-dependent enzyme inhibitors), we conducted an in vitro screen in order to identify inhibitors for CBS using a primary 7-azido-4-methylcoumarin (AzMc) screen to detect CBS-derived hydrogen sulfide (H₂S) production. Initial hits were subjected to counterscreens using the methylene blue assay (a secondary assay to measure H₂S production) and were assessed for their ability to quench the H₂S signal produced by the H₂S donor compound GYY4137. Four compounds, hexachlorophene, tannic acid, aurintricarboxylic acid and benserazide showed concentration-dependent CBS inhibitory actions without scavenging H₂S released from GYY4137, identifying them as direct CBS inhibitors. Hexachlorophene (IC₅₀: ∼60 μM), tannic acid (IC₅₀: ∼40 μM) and benserazide (IC₅₀: ∼30 μM) were less potent CBS inhibitors than the two reference compounds AOAA (IC₅₀: ∼3 μM) and NSC67078 (IC₅₀: ∼1 μM), while aurintricarboxylic acid (IC₅₀: ∼3 μM) was equipotent with AOAA. The second reference compound NSC67078 not only inhibited the CBS-induced AzMC fluorescence signal (IC₅₀: ∼1 μM), but also inhibited with the GYY4137-induced AzMC fluorescence signal with (IC₅₀ of ∼6 μM) indicative of scavenging/non-specific effects. Hexachlorophene (IC₅₀: ∼6 μM), tannic acid (IC₅₀: ∼20 μM), benserazide (IC₅₀: ∼20 μM), and NSC67078 (IC₅₀: ∼0.3 μM) inhibited HCT116 colon cancer cells proliferation with greater potency than AOAA (IC₅₀: ∼300 μM). In contrast, although a CBS inhibitor in the cell-free assay, aurintricarboxylic acid failed to inhibit HCT116 proliferation at lower concentrations, and stimulated cell proliferation at 300 μM. Copper-containing compounds present in the libraries, were also found to be potent inhibitors of recombinant CBS; however this activity was due to the CBS inhibitory effect of copper ions themselves. However, copper ions, up to 300 μM, did not inhibit HCT116 cell proliferation. Benserazide was only a weak inhibitor of the activity of the other H₂S-generating enzymes CSE and 3-MST activity (16% and 35% inhibition at 100 μM, respectively) in vitro. Benserazide suppressed HCT116 mitochondrial function and inhibited proliferation of the high CBS-expressing colon cancer cell line HT29, but not the low CBS-expressing line, LoVo. The major benserazide metabolite 2,3,4-trihydroxybenzylhydrazine also inhibited CBS activity and suppressed HCT116 cell proliferation in vitro. In an in vivo study of nude mice bearing human colon cancer cell xenografts, benserazide (50 mg/kg/day s.q.) prevented tumor growth. In silico docking simulations showed that benserazide binds in the active site of the enzyme and reacts with the PLP cofactor by forming reversible but kinetically stable Schiff base-like adducts with the formyl moiety of pyridoxal. We conclude that benserazide inhibits CBS activity and suppresses colon cancer cell proliferation and bioenergetics in vitro, and tumor growth in vivo. Further pharmacokinetic, pharmacodynamic and preclinical animal studies are necessary to evaluate the potential of repurposing benserazide for the treatment of colorectal cancers.

Design, synthesis and biological evaluation of a novel Cu2+-selective fluorescence sensor for bio-detection and chelation

A new coumarin-based Cu²⁺-selective fluorescent sensor was designed and synthesized and the ability of this fluorescent sensor for the detection and chelation of Cu²⁺ in cultured cells was investigated.