Heterogeneous copper concentrations in cancerous human prostate tissues

Targeting cuproptosis for cancer therapy: mechanistic insights and clinical perspectives

Cuproptosis is a newly identified form of cell death induced by excessive copper (Cu) accumulation within cells. Mechanistically, cuproptosis results from Cu-induced aggregation of dihydrolipoamide S-acetyltransferase, correlated with the mitochondrial tricarboxylic acid cycle and the loss of iron-sulfur cluster proteins, ultimately resulting in proteotoxic stress and triggering cell death. Recently, cuproptosis has garnered significant interest in tumor research due to its potential as a crucial therapeutic strategy against cancer. In this review, we summarized the cellular and molecular mechanisms of cuproptosis and its relationship with other types of cell death. Additionally, we reviewed the current drugs or strategies available to induce cuproptosis in tumor cells, including Cu ionophores, small compounds, and nanomedicine. Furthermore, we targeted cell metabolism and specific regulatory genes in cancer therapy to enhance tumor sensitivity to cuproptosis. Finally, we discussed the feasibility of targeting cuproptosis to overcome tumor chemotherapy and immunotherapy resistance and suggested future research directions. This study suggested that targeting cuproptosis could open new avenues for developing tumor therapy.

Cuproptosis: Mechanism, role, and advances in urological malignancies

Prostate, bladder, and kidney cancers are the most common malignancies of the urinary system. Chemotherapeutic drugs are generally used as adjuvant treatment in the middle, late, or recurrence stages after surgery for urologic cancers. However, traditional chemotherapy is plagued by problems such as poor efficacy, severe side effects, and complications. Copper-containing nanomedicines are promising novel cancer treatment modalities that can potentially overcome these disadvantages. Copper homeostasis and cuproptosis play crucial roles in the development, adaptability, and therapeutic sensitivity of urological malignancies. Cuproptosis refers to the direct binding of copper ions to lipoylated components of the tricarboxylic acid cycle, leading to protein oligomerization, loss of iron-sulfur proteins, proteotoxic stress, and cell death. This review focuses on copper homeostasis and cuproptosis as well as recent findings on copper and cuproptosis in urological malignancies. Furthermore, we highlight the potential therapeutic applications of copper- and cuproptosis-targeted therapies to better understand cuproptosis-based drugs for the treatment of urological tumors in the future.

Myricetin causes site-specific DNA damage via reactive oxygen species generation by redox interactions with copper ions

Myricetin (MYR), found in tea and berries, may have preventive effects on diseases, including Alzheimer's disease and cancer. However, MYR is also a mutagen, inducing DNA damage in the presence of metal ions. We have studied the molecular mechanisms of DNA damage by MYR in the presence of Cu(II) (MYR+Cu). Using 32P-5'-end-labeled DNA fragments, we analyzed site-specific DNA damage caused by MYR+Cu. MYR+Cu caused concentration-dependent DNA strand breaks and base alterations, leading to cleavage of DNA at thymine, cytosine, and guanine nucleotides. Formation of the oxidative DNA damage indicator, 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG), in calf thymus DNA was increased by MYR+Cu. The production of 8-oxodG in MYR-treated HL-60 cells was significantly higher than in HP100 cells, which are more resistant to H2O2 than are HL-60 cells. Reactive oxygen species (ROS) scavengers were used to elucidate the mechanism of DNA damage. DNA damage was not inhibited by typical free hydroxyl radical (•OH) scavengers such as ethanol, mannitol, or sodium formate. However, methional, catalase, and bathocuproine inhibited DNA damage induced by MYR+Cu. These results suggest that H2O2, Cu(I), and ROS other than •OH are involved in MYR+Cu-induced DNA damage. We conclude that the Cu(I)/Cu(II) redox cycle and concomitant H2O2 production via autoxidation of MYR generate a complex of H2O2 and Cu(I), probably Cu(I)-hydroperoxide, which induces oxidative DNA damage.

Addressing the gaps in homeostatic mechanisms of copper and copper dithiocarbamate complexes in cancer therapy: a shift from classical platinum-drug mechanisms

The platinum drug, cisplatin, is considered as among the most successful medications in cancer treatment. However, due to its inherent toxicity and resistance limitations, research into other metal-based non-platinum anticancer medications with diverse mechanisms of action remains an active field. In this regard, copper complexes feature among non-platinum compounds which have shown promising potential as effective anticancer drugs. Moreover, the interesting discovery that cancer cells can alter their copper homeostatic processes to develop resistance to platinum-based treatments leads to suggestions that some copper compounds can indeed re-sensitize cancer cells to these drugs. In this work, we review copper and copper complexes bearing dithiocarbamate ligands which have shown promising results as anticancer agents. Dithiocarbamate ligands act as effective ionophores to convey the complexes of interest into cells thereby influencing the metal homeostatic balance and inducing apoptosis through various mechanisms. We focus on copper homeostasis in mammalian cells and on our current understanding of copper dysregulation in cancer and recent therapeutic breakthroughs using copper coordination complexes as anticancer drugs. We also discuss the molecular foundation of the mechanisms underlying their anticancer action. The opportunities that exist in research for these compounds and their potential as anticancer agents, especially when coupled with ligands such as dithiocarbamates, are also reviewed.

Disordered serum essential element levels are associated with increased risk of kidney tumors

Essential elements play vital roles in the regulation of carcinogenesis. We aimed to investigate the relationship between essential elements and kidney tumors. This study included 72 healthy individuals and 100 kidney tumor patients. The concentrations of cobalt (Co), chromium (Cr), copper (Cu), iron (Fe), manganese (Mn), nickel (Ni), selenium (Se), and zinc (Zn) were determined by inductively coupled plasma mass spectrometry. The random forest model was used to evaluate the importance of each variable by using the randomForest package. The associations between essential elements and clinical tumor characteristics were examined by the Mann-Whitney U-test, and the log-rank test was used to assess the Kaplan-Meier curves. The levels of Co, Cr, Fe, Mn, Ni, and Zn in patients with kidney tumors were significantly lower. In the random forest model, the top two metallic features were Co and Zn. The Kaplan-Meier curve showed that patients with lower Co, Se, and Zn levels exhibited lower progression-free survival. In summary, this study gathered evidence that disordered essential elements are associated with kidney tumors and thus opens a new path to elucidate the etiology of kidney tumors from the perspective of environmental health and safety.

Effect of Copper and Selenium Supplementation on the Level of Elements in Rats' Femurs under Neoplastic Conditions

A study was conducted to determine the effect of long-term supplementation with selenium and copper, administered at twice the level used in the standard diet of rats, on the content of selected elements in the femoral bones of healthy rats and rats with implanted LNCaP cancer cells. After an adaptation period, the animals were randomly divided into two experimental groups. The rats in the experimental group were implanted with prostate cancer cells. The rats in the control group were kept in the same conditions as those in the experimental group and fed the same diet, but without implanted cancer cells. The cancer cells (LNCaP) were intraperitoneally implanted in the amount of 1 × 106 (in PBS 0.4 mL) at the age of 90 days. The content of elements in the samples was determined by a quadrupole mass spectrometer with inductively coupled plasma ionization (ICP-MS). In the femoral bones of rats with implanted LNCaP cells, in the case of the standard diet and the copper-enriched diet, there was a marked decreasing trend in the content of the analysed elements relative to the control rats. This may indicate slow osteolysis taking place in the bone tissue. Contrasting results were obtained for the diet enriched with selenium; there was no significant reduction in the level of these elements, and there was even an increase in the concentrations of Fe and K in the bones of rats with implanted LNCaP cells. Particularly, numerous changes in the mineral composition of the bones were generated by enriching the diet with copper. The elements that most often underwent changes (losses) in the bones were cobalt, iron, manganese and molybdenum. The changes observed, most likely induced by the implantation of LNCaP cells, may indicate a disturbance of mineral homeostasis.

Laser Ablation ICP-MS Analysis of Chemically Different Regions of Rat Prostate Gland with Implanted Cancer Cells

The comparison of tissues analyzed by LA-ICP-MS is challenging in many aspects, both medical and mathematical. The concept of distinguishing regions of interest (ROIs) was proposed in the literature, allowing for data reduction and targeted comparative analysis. ROIs can be drawn before any analysis, by indicating the anatomical parts of tissue, or after the first step of analysis, by using elemental distribution maps and characteristic regions of enrichment in selected elements. A simple method for identifying different regions, without the manual extraction of image fragments, is highly needed in biological experiments, where large groups of individuals (with samples taken from each of them) is very common. In the present study, two ROIs were distinguished: (1) tissue-rich in fat (and tissue-poor in water); and (2) tissue-rich in water (and tissue-poor in fat). ROIs were extracted mathematically, using an algorithm based on the relationship between 13C and 23Na signal intensities. A cut-off point was indicated in the point of the simultaneous decrease in 13C and increase in 23Na signal intensity. Separate analyses of chemically different ROIs allow for targeted comparison, which is a great advantage of laser ablation over liquid introductions to ICP-MS. In the present experiment, tissues were provided from animals with implanted prostate cancer cells as well as supplemented with mineral compounds particularly important both for prostate gland functions (Zn and Se) and neoplastic processes (Ca, Fe, and Cu). One of the goals was to try to determine whether dietary supplementation qualitatively and quantitatively affects the mineral composition of the prostate gland.

Dynamic nanoassembly-based drug delivery system (DNDDS): Learning from nature

Dynamic nanoassembly-based drug delivery system (DNDDS) has evolved from being a mere curiosity to emerging as a promising strategy for high-performance diagnosis and/or therapy of various diseases. However, dynamic nano-bio interaction between DNDDS and biological systems remains poorly understood, which can be critical for precise spatiotemporal and functional control of DNDDS in vivo. To deepen the understanding for fine control over DNDDS, we aim to explore natural systems as the root of inspiration for researchers from various fields. This review highlights ingenious designs, nano-bio interactions, and controllable functionalities of state-of-the-art DNDDS under endogenous or exogenous stimuli, by learning from nature at the molecular, subcellular, and cellular levels. Furthermore, the assembly strategies and response mechanisms of tailor-made DNDDS based on the characteristics of various diseased microenvironments are intensively discussed. Finally, the current challenges and future perspectives of DNDDS are briefly commented.

Age-Related Changes in Zinc, Copper and Selenium Levels in the Human Prostate

Pathophysiological changes in the prostate gland-benign prostatic hyperplasia (BPH) and prostatic adenocarcinoma (PCa)-are closely related to the age of men. In the prostate gland, zinc is of particular importance for its proper functioning, especially with regard to the effects of hormonal disorders. The aim of this study was to evaluate zinc, copper and selenium concentrations in different parts of the prostate gland in relation to age and the nature of pathological changes. Zinc and copper were determined by the AAS method and selenium by the spectrofluorometric method. The concentration of zinc in the central part of the prostate increases with age, and in patients over 36 years it is twice as high as in the peripheral part, where no increase in the level of this element was observed with the age of patients. The above data confirm a possible influence of zinc on the formation of PCa (located mostly in the peripheral part of the prostate, with low levels of zinc) and BPH in the central part where the levels of this element are the highest. The results apparently confirm the disturbed homeostasis of zinc and other essential elements in the etiology of BPH and PCa.

64CuCl2 PET/CT as a potential new imaging method in prostate cancer: illusion or reality?

Copper (Cu) is an essential element for many cellular functions, including proliferation and angiogenesis. High serum Cu levels have been demonstrated in patients with neoplasia as well as high intra-tumoral Cu levels have been reported. Preclinical and clinical evidences suggest its use, in the form of ⁶⁴Copper chloride (⁶⁴CuCl<inf>2</inf>), as metabolic PET tracer in cancer diagnosis and therapy. Specifically, the use of ⁶⁴CuCl<inf>2</inf> in human prostate cancer (PCa) evidenced a high uptake of ⁶⁴CuCl<inf>2</inf> in tumoral prostate and involved regional lymph nodes in a staging setting and high sensitivity for local recurrence and lymph nodes detection in restaging, indicating its great potential. However, further and more solid clinical evidences are needed. On the other hand, ⁶⁴CuCl<inf>2</inf> seems to be a promising radiometabolic drug with great cytotoxic abilities on PCa cells. We have collected the most recent and relevant findings on its potential uses and limitations for the study and treatment of PCa, together with its possible translation in daily clinical practice.

Isoquinoline thiosemicarbazone displays potent anticancer activity with in vivo efficacy against aggressive leukemias

A potent class of isoquinoline-based α-N-heterocyclic carboxaldehyde thiosemicarbazone (HCT) compounds has been rediscovered; based upon this scaffold, three series of antiproliferative agents were synthesized through iterative rounds of methylation and fluorination modifications, with anticancer activities being potentiated by physiologically relevant levels of copper. The lead compound, HCT-13, was highly potent against a panel of pancreatic, small cell lung carcinoma, prostate cancer, and leukemia models, with IC₅₀ values in the low-to-mid nanomolar range. Density functional theory (DFT) calculations showed that fluorination at the 6-position of HCT-13 was beneficial for ligand-copper complex formation, stability, and ease of metal-center reduction. Through a chemical genomics screen, we identify DNA damage response/replication stress response (DDR/RSR) pathways, specifically those mediated by ataxia-telangiectasia and Rad3-related protein kinase (ATR), as potential compensatory mechanism(s) of action following HCT-13 treatment. We further show that the cytotoxicity of HCT-13 is copper-dependent, that it promotes mitochondrial electron transport chain (mtETC) dysfunction, induces production of reactive oxygen species (ROS), and selectively depletes guanosine nucleotide pools. Lastly, we identify metabolic hallmarks for therapeutic target stratification and demonstrate the in vivo efficacy of HCT-13 against aggressive models of acute leukemias in mice.

Association between serum heavy metals and prostate cancer risk - A multiple metal analysis

BACKGROUND

Prostate cancer is one of the most prevalent cancers in men. Exposure to heavy metals and their association with prostate cancer risk has been studied extensively, but combined effects remain largely inconclusive.

OBJECTIVES

To elucidate the association between serum concentrations of heavy metals and prostate cancer risk.

METHODS

Inductively coupled plasma mass spectrometry (ICP-MS) was used to determine the concentrations of a panel of 10 heavy metals (Mn, Cu, Zn, As, Se, Sb, Co, Cu, Cd and Pb) in serum samples of 141 cases and 114 controls in the Singapore Prostate Cancer Study. Linear probit regression models were used to estimate risk differences (RDs) and 95% confidence intervals (CIs) for the associations between log-centered serum metal concentrations and prostate cancer risk with adjustment for potential confounders. Bayesian kernel machine regression (BKMR) models were used to account for nonlinear, interactive, and joint metal effects.

RESULTS

Using probit regression, four heavy metals (As, Zn, Mn, Sb) were significantly and positively associated with prostate cancer risk in the unadjusted models. Using BKMR analysis, both As and Zn had positive risk differences on prostate cancer risk when all other metals were held fixed at the 25th and 50th percentiles (RD, 25th percentile: As: 0.15, Zn: 0.19, RD, 50th percentile: As: 0.45, Zn: 0.37). In addition, the overall mixture risk difference was positive and the 95% credible intervals did not include 0 when all metals in the mixture were jointly above their 55th percentile, as compared to when all metals were below their median values.

CONCLUSIONS

In summary, we found positive associations between the serum levels of As and Zn and prostate cancer risk on the risk difference scale using BKMR models. The overall mixture effect was also associated with increased prostate cancer risk. Future studies are warranted to validate these findings in prospective studies.

Copper homeostasis as target of both consolidated and innovative strategies of anti-tumor therapy

BACKGROUND

Copper was reported to be involved in the onset and progression of cancer. Proteins in charge of copper uptake and distribution, as well as cuproenzymes, are altered in cancer. More recently, proteins involved in signaling cascades, regulating cell proliferation, and anti-apoptotic protein factors were found to interact with copper. Therefore, therapeutic strategies using copper complexing molecules have been proposed for cancer therapy and used in clinical trials.

OBJECTIVES

This review will focus on novel findings about the involvement of copper and cupro-proteins in cancer dissemination process, epithelium to mesenchymal transition and vascularization. Particularly, implication of well-established (e.g. lysil oxidase) or newly identified copper-binding proteins (e.g. MEMO1), as well as their interplay, will be discussed. Moreover, we will describe recently synthesized copper complexes, including plant-derived ones, and their efficacy in contrasting cancer development.

CONCLUSIONS

The research on the involvement of copper in cancer is still an open field. Further investigation is required to unveil the mechanisms involved in copper delivery to the novel copper-binding proteins, which may identify other possible gene and protein targets for cancer therapy.

Oxidative damage in patients with benign prostatic hyperplasia and prostate cancer co-exposed to phthalates and to trace elements

Evidence indicates that prostates exposed to environmental endocrine disruptors and trace metals will cause adverse health outcomes. We assessed the association between urinary phthalate metabolites and serum trace metal levels, and oxidative damage in benign prostatic hyperplasia (BPH) patients, prostate cancer (PCa) patients, and healthy controls. Levels of cadmium (Cd), nickel (Ni), and copper (Cu) were significantly higher in BPH patients than in controls, and mercury (Hg) was highest in PCa patients. An Hg level >1 μg/L posed a significant risk (OR: 42.86, 95% CI: 1.092-1684) for PCa, but a zinc (Zn) level >1 μg/L was marginally negative (OR: 0.979, 95% CI: 0.957-1.002). We also found strong associations between PCa and mono-isononyl phthalate (MiNP), and between BPH and mono-isodecyl phthalate (MiDP), malonyldialdehyde (MDA) were significantly higher in PCa and BPH patients than in controls; 8‑hydroxydeoxyguanosine (8‑OH‑dG) and DNA strand breakage were highest in BPH patients and lowest in controls. When the prostate was simultaneously co-exposed to phthalates and trace metals, phthalates had a less significant effect on PCa and BPH. Thus, we hypothesize that, for patients with prostate disease, exposure to trace metals is more significant than is exposure to phthalates.

Copper as a target for prostate cancer therapeutics: copper-ionophore pharmacology and altering systemic copper distribution

Copper-ionophores that elevate intracellular bioavailable copper display significant therapeutic utility against prostate cancer cells in vitro and in TRAMP (Transgenic Adenocarcinoma of Mouse Prostate) mice. However, the pharmacological basis for their anticancer activity remains unclear, despite impending clinical trails. Herein we show that intracellular copper levels in prostate cancer, evaluated in vitro and across disease progression in TRAMP mice, were not correlative with copper-ionophore activity and mirrored the normal levels observed in patient prostatectomy tissues (Gleason Score 7 & 9). TRAMP adenocarcinoma cells harbored markedly elevated oxidative stress and diminished glutathione (GSH)-mediated antioxidant capacity, which together conferred selective sensitivity to prooxidant ionophoric copper. Copper-ionophore treatments [CuII(gtsm), disulfiram & clioquinol] generated toxic levels of reactive oxygen species (ROS) in TRAMP adenocarcinoma cells, but not in normal mouse prostate epithelial cells (PrECs). Our results provide a basis for the pharmacological activity of copper-ionophores and suggest they are amendable for treatment of patients with prostate cancer. Additionally, recent in vitro and mouse xenograft studies have suggested an increased copper requirement by prostate cancer cells. We demonstrated that prostate adenocarcinoma development in TRAMP mice requires a functional supply of copper and is significantly impeded by altered systemic copper distribution. The presence of a mutant copper-transporting Atp7b protein (tx mutation: A4066G/Met1356Val) in TRAMP mice changed copper-integration into serum and caused a remarkable reduction in prostate cancer burden (64% reduction) and disease severity (grade), abrogating adenocarcinoma development. Implications for current clinical trials are discussed.

A cocktail of 165Er(iii) and Gd(iii) complexes for quantitative detection of zinc using SPECT and MRI

Quantitative zinc determination by nuclear and MR imaging using two Ln³⁺ complexes, including purified ¹⁶⁵Er³⁺, indispensable for metal ion quantification.

Recent views of heavy metals as possible risk factors and potential preventive and therapeutic agents in prostate cancer

Prostate cancer is the most common cancer in men in many industrialized countries. A role for androgens in prostate tumor progression is well recognized, while estrogens may cooperate with androgens in prostate carcinogenesis. The incidence of prostate cancer is highly variable in the different countries, suggesting an important role of environmental factors. Heavy metals are common environmental contaminants and some of them are confirmed or suspected human carcinogens. Some metals are endowed with estrogenic and/or androgenic activities and may play a role as cancer risk factors through this mechanism. Moreover, prostate cancer may present alterations in the intracellular balance of trace metals, such as zinc and copper, which are involved in several regulatory proteins. Herein, we review the possible role of environmental heavy metals and of metal-dyshomeostasis in prostate cancer development and promotion as well as the potential use of some metals in the prevention and therapy of prostate cancer.

Exploring saccharinate-tetrazoles as selective Cu(ii) ligands: structure, magnetic properties and cytotoxicity of copper(ii) complexes based on 5-(3-aminosaccharyl)-tetrazoles

Saccharinate-tetrazolesTSand2MTSbind selectively to copper(ii). The resulting copper complexes have shown a huge increase in thein vitrocytotoxicity against hepatic carcinoma cells (HepG2) compared to the corresponding nontoxic free ligands.

Targeting copper in cancer therapy: 'Copper That Cancer'

Copper is an essential micronutrient involved in fundamental life processes that are conserved throughout all forms of life. The ability of copper to catalyze oxidation-reduction (redox) reactions, which can inadvertently lead to the production of reactive oxygen species (ROS), necessitates the tight homeostatic regulation of copper within the body. Many cancer types exhibit increased intratumoral copper and/or altered systemic copper distribution. The realization that copper serves as a limiting factor for multiple aspects of tumor progression, including growth, angiogenesis and metastasis, has prompted the development of copper-specific chelators as therapies to inhibit these processes. Another therapeutic approach utilizes specific ionophores that deliver copper to cells to increase intracellular copper levels. The therapeutic window between normal and cancerous cells when intracellular copper is forcibly increased, is the premise for the development of copper-ionophores endowed with anticancer properties. Also under investigation is the use of copper to replace platinum in coordination complexes currently used as mainstream chemotherapies. In comparison to platinum-based drugs, these promising copper coordination complexes may be more potent anticancer agents, with reduced toxicity toward normal cells and they may potentially circumvent the chemoresistance associated with recurrent platinum treatment. In addition, cancerous cells can adapt their copper homeostatic mechanisms to acquire resistance to conventional platinum-based drugs and certain copper coordination complexes can re-sensitize cancer cells to these drugs. This review will outline the biological importance of copper and copper homeostasis in mammalian cells, followed by a discussion of our current understanding of copper dysregulation in cancer, and the recent therapeutic advances using copper coordination complexes as anticancer agents.