Cyclodextrin Diethyldithiocarbamate Copper II Inclusion Complexes: A Promising Chemotherapeutic Delivery System against Chemoresistant Triple Negative Breast Cancer Cell Lines

Copper homeostasis and Cuprotosis: Exploring novel therapeutic strategies for connective tissue diseases

Copper is an indispensable element for human health, with its balance being critical to prevent the onset of diseases, particularly those affecting connective tissues. Imbalances in copper levels can lead to pathological alterations. Research indicates that copper supplements and chelators hold promise for the treatment of certain conditions, yet the precise mechanisms by which copper imbalances and the cell death mechanism known as cuprotosis contribute to connective tissue diseases remain elusive. This paper delves into the potential role of copper imbalance and cuprotosis in connective tissue diseases and evaluates the underlying cellular mechanisms. The goal is to offer practical insights into targeted therapies for dysregulated copper metabolism, with the aim of devising novel strategies for the treatment of connective tissue diseases.

Cuproptosis: a promising new target for breast cancer therapy

Breast cancer (BC) is the leading cause of cancer-related mortality among women globally, affecting approximately one-quarter of all female cancer patients and accounting for one-sixth of cancer-related deaths in women. Despite significant advancements in diagnostic and therapeutic approaches, breast cancer treatment remains challenging due to issues such as recurrence and metastasis. Recently, a novel form of regulated cell death, termed cuproptosis, has been identified. This process disrupts mitochondrial respiration by targeting the copper-dependent cellular pathways. The role of cuproptosis has been extensively investigated in various therapeutic contexts, including chemotherapy, immunotherapy, radiotherapy, and nanotherapy, with the development of novel drugs significantly improving clinical outcomes. This article aims to further elucidate the connection between cuproptosis and breast cancer, focusing on its therapeutic targets, signaling pathways, and potential biomarkers that could enhance treatment strategies. These insights may offer new opportunities for improved patient care and outcomes in breast cancer therapy.

Exploring Disulfiram's Anticancer Potential: PLGA Nano-Carriers for Prolonged Drug Delivery and Potential Improved Therapeutic Efficacy

Disulfiram (DS) has been shown to have potent anti-cancer activity; however, it is also characterised by its low water solubility and rapid metabolism in vivo. Biodegradable polylactic-co-glycolic acid (PLGA) polymers have been frequently employed in the manufacturing of PLGA nano-carrier drug delivery systems. Thus, to develop DS-loaded PLGA nanoparticles (NPs) capable of overcoming DS's limitations, two methodologies were used to formulate the NPs: direct nanoprecipitation (DNP) and single emulsion/solvent evaporation (SE), followed by particle size reduction. The DNP method was demonstrated to produce NPs of superior characteristics in terms of size (151.3 nm), PDI (0.083), charge (-37.9 mV), and loading efficiency (65.3%). Consequently, NPs consisting of PLGA and encapsulated DS coated with mPEG2k-PLGA at adjustable ratios were prepared using the DNP method. Formulations were then characterised, and their stability in horse serum was assessed. Results revealed the PEGylated DS-loaded PLGA nano-carriers to be more efficient; hence, in-vitro studies testing these formulations were subsequently performed using two distinct breast cancer cell lines, showing great potential to significantly enhance cancer therapy.

Cyclodextrin encapsulation enabling the anticancer repositioning of disulfiram: Preparation, analytical and in vitro biological characterization of the inclusion complexes

Drug repositioning is a high-priority and feasible strategy in the field of oncology research, where the unmet medical needs are continuously unbalanced. Disulfiram is a potential non-chemotherapeutic, adjuvant anticancer agent. However, the clinical translation is limited by the drug's poor bioavailability. Therefore, the molecular encapsulation of disulfiram with cyclodextrins is evaluated to enhance the solubility and stability of the drug. The present work describes for the first time the complexation of disulfiram with randomly methylated-β-cyclodextrin. A parallel analytical andin vitrobiological comparison of disulfiram inclusion complexes with hydroxypropyl-β-cyclodextrin, randomly methylated-β-cyclodextrin and sulfobutylether-β-cyclodextrin is conducted. A significant drug solubility enhancement by about 1000-folds and fast dissolution in 1 min is demonstrated. Thein vitrodissolution-permeation studies and proliferation assays demonstrate the solubility-dependent efficacy of the drug. Throughout the different cancer cell lines' characteristics and disulfiram unspecific antitumoral activity, the inhibitory efficacy of the cyclodextrin encapsulated drug on melanoma (IC50 about 100 nM) and on glioblastoma (IC50 about 7000 nM) cell lines differ by a magnitude. This pre-formulation screening experiment serves as a proof of concept of using cyclodextrin encapsulation as a platform tool for further drug delivery development in repositioning areas.

Cuproptosis: A novel therapeutic target for overcoming cancer drug resistance

Cuproptosis is a newly identified form of cell death driven by copper. Recently, the role of copper and copper triggered cell death in the pathogenesis of cancers have attracted attentions. Cuproptosis has garnered enormous interest in cancer research communities because of its great potential for cancer therapy. Copper-based treatment exerts an inhibiting role in tumor growth and may open the door for the treatment of chemotherapy-insensitive tumors. In this review, we provide a critical analysis on copper homeostasis and the role of copper dysregulation in the development and progression of cancers. Then the core molecular mechanisms of cuproptosis and its role in cancer is discussed, followed by summarizing the current understanding of copper-based agents (copper chelators, copper ionophores, and copper complexes-based dynamic therapy) for cancer treatment. Additionally, we summarize the emerging data on copper complexes-based agents and copper ionophores to subdue tumor chemotherapy resistance in different types of cancers. We also review the small-molecule compounds and nanoparticles (NPs) that may kill cancer cells by inducing cuproptosis, which will shed new light on the development of anticancer drugs through inducing cuproptosis in the future. Finally, the important concepts and pressing questions of cuproptosis in future research that should be focused on were discussed. This review article suggests that targeting cuproptosis could be a novel antitumor therapy and treatment strategy to overcome cancer drug resistance.

Preparation and Characterisation of Zinc Diethyldithiocarbamate-Cyclodextrin Inclusion Complexes for Potential Lung Cancer Treatment

Zinc diethyldithiocarbamate (Zn (DDC)2), a disulfiram metabolite (anti-alcoholism drug), has shown a strong anti-cancer activity in vitro. However, its application was limited by its low aqueous solubility and rapid metabolism. In this study, the solubility enhancement of Zn (DDC)2 is investigated by forming inclusion complexes with cyclodextrins. The inclusion complexes were prepared using two different types of beta-cyclodextrins, SBE-CD and HP-CD. Phase solubility diagrams for the resulting solutions were assessed; subsequently, the solutions were freeze-dried for further characterisation studies using DSC, TGA, XRD, and FTIR. The cytotoxic activity of the produced inclusion complexes was evaluated on human lung carcinoma cells using the MTT assay. The solubility of Zn (DDC)2 increased significantly upon adding beta-cyclodextrins, reaching approximately 4 mg/mL for 20% w/w CD solutions. The phase solubility diagram of Zn (DDC)2 was of the Ap-type according to the Higuchi and Connors model. Characterisation studies confirmed the inclusion of the amorphous drug in the CD-Zn (DDC)2 complexes. The cytotoxicity of Zn (DDC)2 was enhanced 10-fold by the inclusion complexes compared to the free drug. Overall, the resulting CD-Zn (DDC)2 inclusion complexes have a potential for treatment against lung cancer.

In vitro and in vivo evaluation of diethyldithiocarbamate with copper ions and its liposomal formulation for the treatment of Staphylococcus aureus and Staphylococcus epidermidis biofilms

Surgical site infections (SSIs) are mainly caused by Staphylococcus aureus (S. aureus) and Staphylococcus epidermidis (S. epidermidis) biofilms. Biofilms are aggregates of bacteria embedded in a self-produced matrix that offers protection against antibiotics and promotes the spread of antibiotic-resistance in bacteria. Consequently, antibiotic treatment frequently fails, resulting in the need for alternative therapies. The present study describes the in vitro efficacy of the Cu(DDC)₂ complex (2:1 M ratio of diethyldithiocarbamate (DDC^-) and Cu²⁺) with additional Cu²⁺ against S. aureus and S. epidermidis biofilms in models mimicking SSIs and in vitro antibacterial activity of a liposomal Cu(DDC)₂ + Cu²⁺ formulation. The in vitro activity on S. aureus and S. epidermidis biofilms grown on two hernia mesh materials and in a wound model was determined by colony forming unit (CFU) counting. Cu²⁺-liposomes and Cu(DDC)₂-liposomes were prepared, and their antibacterial activity was assessed in vitro using the alamarBlue assay and CFU counting and in vivo using a Galleria mellonella infection model. The combination of 35 μM DDC^- and 128 μM Cu²⁺ inhibited S. aureus and S. epidermidis biofilms on meshes and in a wound infection model. Cu(DDC)₂-liposomes + free Cu²⁺ displayed similar antibiofilm activity to free Cu(DDC)₂ + Cu²⁺, and significantly increased the survival of S. epidermidis-infected larvae. Whilst Cu(DDC)₂ + Cu²⁺ showed substantial antibiofilm activity in vitro against clinically relevant biofilms, its application in mammalian in vivo models is limited by solubility. The liposomal Cu(DDC)₂ + Cu²⁺ formulation showed antibiofilm activity in vitro and antibacterial activity and low toxicity in G. mellonella, making it a suitable water-soluble formulation for future application on infected wounds in animal trials.

Copper (II) Species with Improved Anti-Melanoma and Antibacterial Activity by Inclusion in β-Cyclodextrin

To improve their biological activity, complexes [Cu(bipy)(dmtp)₂(OH₂)](ClO₄)₂·dmtp (1) and [Cu(phen)(dmtp)₂(OH₂)](ClO₄)₂·dmtp (2) (bipy 2,2'-bipyridine, phen: 1,10-phenantroline, and dmtp: 5,7-dimethyl-1,2,4-triazolo [1,5-a]pyrimidine) were included in β-cyclodextrins (β-CD). During the inclusion, the co-crystalized dmtp molecule was lost, and UV-Vis spectra together with the docking studies indicated the synthesis of new materials with 1:1 and 1:2 molar ratios between complexes and β-CD. The association between Cu(II) compounds and β-CD has been proven by the identification of the components' patterns in the IR spectra and powder XRD diffractograms, while solid-state UV-Vis and EPR spectra analysis highlighted a slight modification of the square-pyramidal stereochemistry around Cu(II) in comparison with precursors. The inclusion species are stable in solution and exhibit the ability to scavenge or trap ROS species (O₂·^- and HO·) as indicated by the EPR experiments. Moreover, the two inclusion species exhibit anti-proliferative activity against murine melanoma B16 cells, which has been more significant for (2)@β-CD in comparison with (2). This behavior is associated with a cell cycle arrest in the G0/G1 phase. Compared with precursors, (1a)@β-CD and (2a)@β-CD exhibit 17 and 26 times more intense activity against planktonic Escherichia coli, respectively, while (2a)@β-CD is 3 times more active against the Staphylococcus aureus strain.

The treatment of hepatocellular carcinoma with SP94 modified asymmetrical bilayer lipid-encapsulated Cu(DDC)2 nanoparticles facilitating Cu accumulation in the tumor

BACKGROUND

Copper diethyldithiocarbamate (Cu(DDC)₂) has been demonstrated to possess excellent antitumor activity. However, the extremely poor water solubility of Cu(DDC)₂ bring difficulty for its formulation research. In this study, we aim to develop a novel nanocarrier for Cu(DDC)₂ delivery to overcome this obstacle and enhance antitumor activity.

METHODS

The SP94 modified asymmetrical bilayer lipid-encapsulated Cu(DDC)₂ nanoparticles (DCDP) was established by combining the method of inverse microemulsion aggregation and thin-film dispersion. In vitro cellular assays and in vivo tumor-xenograft experiments were conducted to evaluate the tumor chemotherapeutic effect of DCDP. And the vital role of copper ions played in DSF or DDC (DSF/DDC)-based cancer chemotherapy was also explored.

RESULTS

DCDP with an encapsulation efficiency (EE%) of 74.0% were successfully prepared. SP94 modification facilitated cellular intake for DCDP, and promoted apoptosis to repress tumor cell proliferation (IC₅₀, 200 nM). And DCDP effectively inhibited tumor growth with a high tumor inhibition rate of 74.84%. Furthermore, Cu(DDC)₂ was found to facilitate the copper ion accumulation in tumor tissues, which is beneficial to therapy with high potency.

CONCLUSION

DCDP exhibited high-efficient tumor chemotherapeutic efficacy and provided a novel strategy for investigating the anticancer mechanism of Cu(DDC)₂.

Preparation and Characterization of Disulfiram and Beta Cyclodextrin Inclusion Complexes for Potential Application in the Treatment of SARS-CoV-2 via Nebulization

Disulfiram (DS), known as an anti-alcoholism drug, has shown a potent antiviral activity. Still, the potential clinical application of DS is limited by its low water solubility and rapid metabolism. Cyclodextrins (CDs) have been widely used to improve the solubility of drugs in water. In this study, five concentrations of hydroxypropyl β-cyclodextrin (HP) and sulfobutyl ether β-cyclodextrin (SBE) were used to form inclusion complexes of DS for enhanced solubility. Solutions were freeze-dried, and the interaction between DS and CD was characterized using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and Fourier transform infrared spectroscopy (FTIR). In addition, the nebulization properties of the DS–CD solutions were studied. The aqueous solubility of DS increased significantly when loaded to either of both CDs. The phase solubility of both complexes was a linear function of the CD concentration (A_L type). Furthermore, physicochemical characterization studies showed a potent inclusion of the drug in the CD–DS complexes. Aerosolization studies demonstrated that these formulations are suitable for inhalation. Overall, the CD inclusion complexes have great potential for the enhancement of DS solubility. However, further studies are needed to assess the efficacy of DS–CD inclusion complexes against SARS-CoV-2 via nebulization.

Disulfiram: A Food and Drug Administration-approved multifunctional role in synergistically drug delivery systems for tumor treatment

Disulfiram (DSF), a Food and Drug Administration (FDA)-approved drug for the treatment of alcoholism, has been found to have antitumor activity. DSF showed better antitumor efficiency when it was used in combination with certain antitumor drugs. DSF plays an important role in cancer treatment. It has been used as multidrug resistance (MDR) modulator to reverse MDR and can also combine with copper ions (Cu²⁺), which will produce copper diethyldithiocarbamate (Cu[DDC]₂) complex with antitumor activity. The synergistic targeted drug delivery for cancer treatment based on DSF, especially the combination with exogenous Cu²⁺ and its forms of administration, has attracted extensive attention in the biomedical field. In this review, we summarize these synergistic delivery systems, in the hope that they will contribute to the continuous optimization and development of more advanced drug delivery systems. Furthermore, we discuss the current limitation and future directions of DSF-based drug delivery systems in the field of tumor therapy. Hopefully, our work may inspire further innovation of DSF-based antitumor drug delivery systems.

Preparation and characterisation of ethambutol with β-cyclodextrin: a comprehensive molecular insight into host-guest interaction

The increase in new cases of drug resistance to first-line drugs such as ethambutol (ETB) makes it necessary to develop improvements for antituberculosis drugs. A new method for improving the bioavailability of active pharmaceutical ingredient (API) was investigated for preventing drug resistance and side-effects of antituberculosis drugs. In this study, an antituberculosis drug delivery system using β-cyclodextrin (β-CD) as the supramolecular carrier of ETB was prepared using the kneading method. The inclusion behaviour of β-CD/ETB inclusion complex in solid and liquid state was investigated. The inclusion complex was characterized using Fourier transform infrared spectroscopy, thermogravimetric analysis, nuclear magnetic resonance (NMR) spectroscopy, and UV-visible spectroscopy. The 1H and nuclear Overhauser effect spectroscopy NMR results indicated the hydrophobic interaction between β-CD and ETB. Meanwhile, the Benesi-Hildebrand equation was used to calculate the formation constant (K) of β-CD/ETB complex in natural condition, pH4, and pH9, which were 105.43, 107.06, and 119.11, respectively. The stoichiometry ratio of β-CD/ETB complex was proven to be 1:1.

One-Step Synthesis of Nanoliposomal Copper Diethyldithiocarbamate and Its Assessment for Cancer Therapy

The metal complex copper diethyldithiocarbamate (CuET) induces cancer cell death by inhibiting protein degradation and induces proteotoxic stress, making CuET a promising cancer therapeutic. However, no clinical formulation of CuET exists to date as the drug is insoluble in water and exhibits poor bioavailability. To develop a scalable formulation, nanoliposomal (LP) CuET was synthesized using ethanol injection as a facile one-step method that is suitable for large-scale manufacturing. The nanoparticles are monodispersed, colloidally stable, and approximately 100 nm in diameter with an encapsulation efficiency of over 80%. LP-CuET demonstrates excellent stability in plasma, minimal size change, and little drug release after six-month storage at various temperatures. Additionally, melanoma cell lines exhibit significant sensitivity to LP-CuET and cellular uptake occurs predominantly through endocytosis in YUMM 1.7 cancer cells. Intracellular drug delivery is mediated by vesicle acidification with more nanoparticles being internalized by melanoma cells compared with RAW 264.7 macrophages. Additionally, the nanoparticles preferentially accumulate in YUMM 1.7 tumors where they induce cancer cell death in vivo. The development and characterization of a stable and scalable CuET formulation illustrated in this study fulfils the requirements needed for a potent clinical grade formulation.

Copper-induced tumor cell death mechanisms and antitumor theragnostic applications of copper complexes

Recent studies found that unbalanced copper homeostasis affect tumor growth, causing irreversible damage. Copper can induce multiple forms of cell death, including apoptosis and autophagy, through various mechanisms, including reactive oxygen species accumulation, proteasome inhibition, and antiangiogenesis. Hence, copper in vivo has attracted tremendous attention and is in the research spotlight in the field of tumor treatment. This review first highlights three typical forms of copper's antitumor mechanisms. Then, the development of diverse biomaterials and nanotechnology allowing copper to be fabricated into diverse structures to realize its theragnostic action is discussed. Novel copper complexes and their clinical applications are subsequently described.

Novel nanoformulated diethyldithiocarbamate complexes with biosynthesized or green chemosynthesized copper oxide nanoparticles: An in vitro comparative anticancer study

Developing more soluble and stable nanoformulation for the potent anticancer complex of copper diethyldithiocarbamate (CD) is extremely desired. Herein, for the first time, CD nanoparticles (NPs) were formulated by chelating diethyldithiocarbamate to bacterially and green chemically prepared copper oxide NPs (Bio CO NPs and Chemo CO NPs, respectively). Chemo CO NPs were produced in simpler and less time-consuming manner with higher NPs homogeneity. These CO NPs were identified, by X-ray diffractometer, as CuO and Cu₂O, respectively. The nanoformulated CD complexes (Bio CD NPs and Chemo CD NPs) which have nanosizes (215.7 nm and 148.1 nm, respectively) with negative zeta potentials (∼-20 mv), exhibited not only high serum stability and solubility but also a potent anticancer effect. More importantly, Chemo CD NPs outperformed Bio CD NPs in the terms of synergistic anticancer index, apoptosis induction (>81% and <54%, respectively) and anti-migration efficacy (≥80% and <71%, respectively). This could be attributed to smaller nanosize and Cu₂O of Chemo CD NPs causing higher cellular uptake with stronger inhibition of aldehyde dehydrogenase 1A1 and more free radical generation in Chemo CD NPs-treated cancer cells than Bio CD NPs. This distinct anticancer efficacy of novel Chemo CD NPs deserves further investigation using animal models.

Recent Advances in Repurposing Disulfiram and Disulfiram Derivatives as Copper-Dependent Anticancer Agents

Copper (Cu) plays a pivotal role in cancer progression by acting as a co-factor that regulates the activity of many enzymes and structural proteins in cancer cells. Therefore, Cu-based complexes have been investigated as novel anticancer metallodrugs and are considered as a complementary strategy for currently used platinum agents with undesirable general toxicity. Due to the high failure rate and increased cost of new drugs, there is a global drive towards the repositioning of known drugs for cancer treatment in recent years. Disulfiram (DSF) is a first-line antialcoholism drug used in clinics for more than 65 yr. In combination with Cu, it has shown great potential as an anticancer drug by targeting a wide range of cancers. The reaction between DSF and Cu ions forms a copper diethyldithiocarbamate complex (Cu(DDC)₂ also known as CuET) which is the active, potent anticancer ingredient through inhibition of NF-κB and ubiquitin-proteasome system as well as alteration of the intracellular reactive oxygen species (ROS). Importantly, DSF/Cu inhibits several molecular targets related to drug resistance, stemness, angiogenesis and metastasis and is thus considered as a novel strategy for overcoming tumour recurrence and relapse in patients. Despite its excellent anticancer efficacy, DSF has proven unsuccessful in several cancer clinical trials. This is likely due to the poor stability, rapid metabolism and/or short plasma half-life of the currently used oral version of DSF and the inability to form Cu(DDC)₂ at relevant concentrations in tumour tissues. Here, we summarize the scientific rationale, molecular targets, and mechanisms of action of DSF/Cu in cancer cells and the outcomes of oral DSF ± Cu in cancer clinical trials. We will focus on the novel insights on harnessing the immune system and hypoxic microenvironment using DSF/Cu complex and discuss the emerging delivery strategies that can overcome the shortcomings of DSF-based anticancer therapies and provide opportunities for translation of DSF/Cu or its Cu(DDC)₂ complex into cancer therapeutics.

Expediting Disulfiram Assays through a Systematic Analytical Quality by Design Approach

An Analytical Quality by Design (AQbD) approach is presented, aiming at the development and validation of an HPLC method for the quantification of disulfiram and copper diethyldithiocarbamate in lipid nanoparticles. Following the definition of the analytical target profile (ATP), encompassing the critical analytical attributes (CAA), a two-level risk assessment strategy (Ishikawa diagram—failure mode and effect analysis (FMEA)) was employed to identify the critical method parameters (CMPs) with an extensive impact on method performance. The behavior of the CMPs (flow rate and mobile phase composition) was further characterized by experimental design, resorting to a face-centered central composite design (FcCCD). Statistical modeling, response surface analysis, and Monte Carlo simulations led to the definition of the Method Operable Design Region (MODR), associated with a negligible risk of failing the predefined CAA specifications. The optimal method was validated according to international regulatory recommendations. Apart from guaranteeing linearity, accuracy, precision, specificity, robustness, and stability, these conditions were found to be suitable for analysis using a different HPLC column and equipment. In a nutshell, the development and optimization strategies, under the comprehensive framework of AQbD, provided an effective, simple, rapid, reliable, and flexible method for routine analysis of the compounds in research or industrial environments.

Sunscreens Containing Cyclodextrin Inclusion Complexes for Enhanced Efficiency: A Strategy for Skin Cancer Prevention

Unprotected exposure of skin to solar ultraviolet radiation (UVR) may damage the DNA of skin cells and can lead to skin cancer. Sunscreens are topical formulations used to protect skin against UVR. The active ingredients of sunscreens are UV filters that absorb, scatter, and/or reflect UVR. Preventing the formation of free radicals and repairing DNA damages, natural antioxidants are also added to sunscreens as a second fold of protection against UVR. Antioxidants can help stabilise these formulations during the manufacturing process and upon application on skin. However, UV filters and antioxidants are both susceptible to degradation upon exposure to sunlight and oxygen. Additionally, due to their poor water solubility, natural antioxidants are challenging to formulate and exhibit limited penetration and bioavailability in the site of action (i.e., deeper skin layers). Cyclodextrins (CDs) are cyclic oligosaccharides that are capable of forming inclusion complexes with poorly soluble drugs, such as antioxidants. In this review, we discuss the use of CDs inclusion complexes to enhance the aqueous solubility of antioxidants and chemical UV filters and provide a protective shield against degradative factors. The role of CDs in providing a controlled drug release profile from sunscreens is also discussed. Finally, incorporating CDs inclusion complexes into sunscreens has the potential to increase their efficiency and hence improve their skin cancer prevention.