Targeting copper in cancer therapy: 'Copper That Cancer'

Biofunctional magnesium-coated Ti6Al4V scaffolds promote autophagy-dependent apoptosis in osteosarcoma by activating the AMPK/mTOR/ULK1 signaling pathway

The recurrence of osteosarcoma (OS) after reconstruction using Ti6Al4V prostheses remains a major problem in the surgical treatment of OS. Modification of the surfaces of Ti6Al4V prostheses with antitumor functions is an important strategy for improving therapeutic outcomes. Magnesium (Mg) coating has been shown to be multifunctional: it exhibits osteogenic and angiogenic properties and the potential to inhibit OS. In this study, we determined the proper concentration of released Mg²⁺ with respect to OS inhibition and biosafety and evaluated the anti-OS effects of Mg-coated Ti6Al4V scaffolds. We found that the release of Mg²⁺ during short-term and long-term degradation could significantly inhibit the proliferation and migration of HOS and 143B cells. Increased cell apoptosis and excessive autophagy were also observed, and further evidence of AMPK/mTOR/ULK1 signaling pathway activation was obtained both in vitro and in vivo, which suggested that the biofunctional scaffolds induce OS inhibition. Our study demonstrates the ability of an Mg coating to inhibit OS and may contribute to the further application of Mg-coated Ti6Al4V prostheses.

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Multifunctional Mg coating is considerable surface modification for Ti6Al4V prostheses.

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Mg²⁺ releasing by the scaffolds could significantly inhibit the proliferation and migration of OS cells.

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The biofunctional scaffolds could inhibit OS by activating autophagy-dependent apoptosis.

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The AMPK/mTOR/ULK-1 pathway was involved in autophagy-depended apoptosis induced by the scaffolds.

Prospective Selective Mechanism of Emerging Senolytic Agents Derived from Flavonoids

Senescent cells (SCs) are associated with the onset and development of multiple chronic diseases. Selective clearance of SCs by senolytic drugs is a potential therapeutic option for a number of age-related diseases. Among senolytic candidates, only dasatinib with quercetin and fisetin meet the rigorous criteria for senolytic drugs, according to a modified version of Koch's postulates. It is astonishing that two of the three agents, i.e., quercetin and fisetin, are flavonoids, although the mechanism by which they preferentially eliminate SCs is unclear. Herein, we propose a possible selective mechanism; prooxidant activities of quercetin or fisetin are inevitably involved in killing apoptosis-resistant SCs. Among the dietary flavonoids, quercetin is a potent redox-active flavonoid with strong prooxidant activities, and transition metals, such as copper and iron, hugely amplify its prooxidant activities. Fisetin, which has higher senolytic activities than quercetin, has higher prooxidant effects than quercetin in the absence or presence of copper. It appears that the prooxidant activity of flavonoids is an important consideration for screening senolytics. SCs accumulate high levels of copper and iron, and the selective mechanism of quercetin or fisetin is probably associated with copper/iron-promoted oxidative damage in SCs. Copper and iron dramatically enhanced the prooxidant effects of the flavonoid, epigallocatechin-3-gallate, having shown a depletion effect on SCs in rats and high therapeutic efficacy in patients with idiopathic pulmonary fibrosis, largely caused by SCs. Further investigation to evaluate whether epigallocatechin-3-gallate is a senolytic drug, according to Koch's postulates, is warranted.

Revealing the Underestimated Anticancer Effect of Azurin by Mechanical Unfolding

As a potential anticancer agent, azurin has attracted extensive attraction among chemists, physicists, and material scientists. Its structural and unfolding/folding information has been partially understood, but some detailed information, such as the difference in the unfolding processes between apo-azurin and holo-azurin, the mechanical stability, and the role of the copper cluster in its stability, has not been addressed adequately, especially at the single-molecule level. Here, we employed AFM-based single-molecule force spectroscopy to investigate the unfolding process of azurin in the apo and holo forms under an external force. The results indicated that the unfolding processes of apo-azurin and holo-azurin are different, and holo-azurin requires a stronger force to unfold than does apo-azurin. The copper cluster exhibited a more significant impact on the stability and the folding process of holo-azurin: the copper cluster was completely broken, and the copper ion left the unfolded azurin during the unfolding process of azurin. We suspected that the presence of the disulfide bond in azurin made the unfolding of the copper cluster different from that in pseudoazurin, which is also a type I copper protein like azurin. Rarely reported in previous studies, the mechanical strength of the Cu-N(His) bond of the copper cluster was obtained in this study, which is weaker than that of most metal-S(Cys) bonds but higher than that of the Fe-N(His) bond. Altogether, our results offer a possible new scenario for azurin to widely extend its anticancer activity.

Tetrahedral Framework Nucleic Acid Delivered RNA Therapeutics Significantly Attenuate Pancreatic Cancer Progression via Inhibition of CTR1-Dependent Copper Absorption

Copper is vital for various life processes, whereas severely toxic at excess level. Intracellular copper homeostasis is strictly controlled by a set of transporters and chaperones encoded by the copper homeostasis genes. Increasing evidence has shown that copper is usually overloaded in multiple malignancies, including pancreatic cancer, which has an extremely poor prognosis. Recently, silencing the SLC31A1 gene, which encodes a major transmembrane copper transporter (CTR1), has been demonstrated to be an effective means for reducing the malignant degree of pancreatic cancer by downregulating the cellular copper levels. Herein, we utilized tetrahedral framework nucleic acids (tFNAs) as vehicles to overcome the biological barriers for delivering small molecular RNAs and efficiently transferred two kinds of CTR1 mRNA-targeted RNA therapeutics, siCTR1 or miR-124, into PANC-1 cells. Both therapeutic tFNAs, termed t-siCTR1 and t-miR-124, prevented copper intake more effective than the free RNA therapeutics via efficiently suppressing the expression of CTR1, thereby significantly attenuating the progression of PANC-1 cells. In this study, therapeutic tFNAs are constructed to target metal ion transporters for the first time, which may provide an effective strategy for future treatment of other metal metabolism disorders.

Angiogenin and Copper Crossing in Wound Healing

Angiogenesis plays a key role in the wound healing process, involving the migration, growth, and differentiation of endothelial cells. Angiogenesis is controlled by a strict balance of different factors, and among these, the angiogenin protein plays a relevant role. Angiogenin is a secreted protein member of the ribonuclease superfamily that is taken up by cells and translocated to the nucleus when the process of blood vessel formation has to be promoted. However, the chemical signaling that activates the protein, normally present in the plasma, and the transport pathways through which the protein enters the cell are still largely unclear. Copper is also an angiogenic factor that regulates angiogenin expression and participates in the activation of common signaling pathways. The interaction between angiogenin and copper could be a relevant mechanism in regulating the formation of new blood vessel pathways and paving the way to the development of new drugs for chronic non-healing wounds.

Copper Isotopes and Copper to Zinc Ratio as Possible Biomarkers for Thyroid Cancer

Thyroid cancer is the most common endocrine cancer. There is no systematic screening for such cancer, and the current challenge is to find potential biomarkers to facilitate an early diagnosis. Copper (Cu) and zinc (Zn) are essential micronutrients involved in the proper functioning of the thyroid gland, and changes in their concentrations have been observed in the development of cancer. Previous studies have highlighted the potential ⁶⁵Cu/⁶³Cu ratio (δ⁶⁵Cu) to be a cancer biomarker. This study tests its sensitivity on plasma samples (n = 46) of Algerian patients with papillary thyroid carcinoma and a set of corresponding biopsies (n = 11). The δ⁶⁵Cu ratio in blood and tumor samples was determined using multi collector inductively coupled plasma-mass spectrometry (MC-ICP-MS), and their corresponding Cu and Zn plasma total concentrations using total reflection X-ray fluorescence (TXRF). Plasma concentrations of Cu were significantly higher (1346.1 ± 328.3 vs. 1060.5 ± 216.1 μg/L, p < 0.0001), and Zn significantly lower (942.1 ± 205.2 vs. 1027.9 ± 151.4 μg/L, p < 0.05) in thyroid cancer patients as compared to healthy controls (n = 50). Accordingly, the Cu/Zn ratio was significantly different between patients and controls (1.5 ± 0.4 vs. 1.0 ± 0.3, p < 0.0001). Furthermore, the δ⁶⁵Cu plasma levels of patients were significantly lower than healthy controls (p < 0.0001), whereas thyroid tumor tissues presented high δ⁶⁵Cu values. These results support the hypothesis that Cu isotopes and plasma trace elements may serve as suitable biomarkers of thyroid cancer diagnosis.

Ternary Copper Complex of L-Glutamine and Phenanthroline as Counterions of Cyclo-Tetravanadate Anion: Experimental–Theoretical Characterization and Potential Antineoplastic Activity

Over the last decade, therapeutic metallodrugs have become substantially effective in the treatment of cancer. Thus, developing new effective anticancer drugs is a significant research area against the continuing increase in cancers worldwide. In the search for heterobimetallic prodrugs containing V/Cu, a new cyclo-tetravanadate was synthesized and characterized by UV-visible and FTIR spectroscopies and single-crystal X-ray diffraction. L-Glutamine and 1,10-phenanthroline allow the crystallization of [Cu(L-Gln)(phen)(H2O)]4[V4O12]∙8(H2O) (1), in which the cyclo-tetravanadate acts as a free anion. Density functional theory (DFT) calculations were carried out to characterize the frontier molecular orbitals and molecular electrostatic potential. Global reactivity indexes were calculated and analyzed to give insight into the cyclo-tetravanadate anion and complex counterions interactions. Also, using Bader’s theory of atoms in molecules (AIM), non-covalent interactions were analyzed. Docking analysis with the Casiopeina-like complex resulting from the hydrolysis of compound 1 provided insights into these complex potential anticancer activities by interacting with DNA/tRNA via H-bonds and hydrophobic interactions. The release of both components could act together or separately, acting as prodrugs with potential dual antineoplastic activities.

SPAAC iClick: progress towards a bioorthogonal reaction in-corporating metal ions

Combining strain-promoted azide-alkyne cycloaddition (SPAAC) and inorganic click (iClick) reactivity provides access to metal 1,2,3-triazolates. Experimental and computational insights demonstrate that iClick reactivity of the tested metal azides (LM-N₃, M = Au, W, Re, Ru and Pt) depends on the accessibility of the azide functionality rather than electronic effects imparted by the metal. SPAAC iClick reactivity with cyclooctyne is observed when the azide functionality is sterically unencumbered, e.g. [Au(N₃)(PPh₃)] (Au-N3), [W(η³-allyl)(N₃)(bpy)(CO)₂] (W-N3), and [Re(N₃)(bpy)(CO)₃] [bpy = 2,2'-bipyridine] (Re-N3). Increased steric bulk and/or preequilibria with high activation barriers prevent SPAAC iClick reactivity for the complexes [Ru(N₃)(Tp)(PPh₃)₂] [Tp = tris(pyrazolyl)borate] (Ru-N3), [Pt(N₃)(CH₃)(PⁱPr₃)₂] [ⁱPr = isopropyl] (Pt(II)-N3), and [Pt(N₃)(CH₃)₃]₄ ((PtN3)4). Based on these computational insights, the SPAAC iClick reactivity of [Pt(N₃)(CH₃)₃(P(CH₃)₃)₂] (Pt(IV)-N3) was successfully predicted.

Innovative therapies for neuroblastoma: The surprisingly potent role of iron chelation in up-regulating metastasis and tumor suppressors and down-regulating the key oncogene, N-myc

Iron is an indispensable requirement for essential biological processes in cancer cells. Due to the greater proliferation of neoplastic cells, their demand for iron is considerably higher relative to normal cells, making them highly susceptible to iron depletion. Understanding this sensitive relationship led to research exploring the effect of iron chelation therapy for cancer treatment. The classical iron-binding ligand, desferrioxamine (DFO), has demonstrated effective anti-proliferative activity against many cancer-types, particularly neuroblastoma tumors, and has the surprising activity of down-regulating the potent oncogene, N-myc, which is a major oncogenic driver in neuroblastoma. Even more significant is the ability of DFO to simultaneously up-regulate the potent metastasis suppressor, N-myc downstream-regulated gene-1 (NDRG1), which plays a plethora of roles in suppressing a variety of oncogenic signaling pathways. However, DFO suffers the disadvantage of demonstrating poor membrane permeability and short plasma half-life, requiring administration by prolonged subcutaneous or intravenous infusions. Considering this, the specifically designed di-2-pyridylketone thiosemicarbazone (DpT) series of metal-binding ligands was developed in our laboratory. The lead agent from the first generation DpT series, di-2-pyridylketone-4,4-dimethyl-3-thiosemicarbazone (Dp44mT), showed exceptional anti-cancer properties compared to DFO. However, it exhibited cardiotoxicity in mouse models at higher dosages. Therefore, a second generation of agents was developed with the lead compound being di-2-pyridylketone-4-cyclohexyl-4-methyl-3-thiosemicarbazone (DpC) that progressed to Phase I clinical trials. Importantly, DpC showed better anti-proliferative activity than Dp44mT and no cardiotoxicity, demonstrating effective anti-cancer activity against neuroblastoma tumors in vivo.

Curcumin and Nano-Curcumin Mitigate Copper Neurotoxicity by Modulating Oxidative Stress, Inflammation, and Akt/GSK-3β Signaling

Copper (Cu) is essential for multiple biochemical processes, and copper sulphate (CuSO₄) is a pesticide used for repelling pests. Accidental or intentional intoxication can induce multiorgan toxicity and could be fatal. Curcumin (CUR) is a potent antioxidant, but its poor systemic bioavailability is the main drawback in its therapeutic uses. This study investigated the protective effect of CUR and N-CUR on CuSO₄-induced cerebral oxidative stress, inflammation, and apoptosis in rats, pointing to the possible involvement of Akt/GSK-3β. Rats received 100 mg/kg CuSO₄ and were concurrently treated with CUR or N-CUR for 7 days. Cu-administered rats exhibited a remarkable increase in cerebral malondialdehyde (MDA), NF-κB p65, TNF-α, and IL-6 associated with decreased GSH, SOD, and catalase. Cu provoked DNA fragmentation, upregulated BAX, caspase-3, and p53, and decreased BCL-2 in the brain of rats. N-CUR and CUR ameliorated MDA, NF-κB p65, and pro-inflammatory cytokines, downregulated pro-apoptotic genes, upregulated BCL-2, and enhanced antioxidants and DNA integrity. In addition, both N-CUR and CUR increased AKT Ser473 and GSK-3β Ser9 phosphorylation in the brain of Cu-administered rats. In conclusion, N-CUR and CUR prevent Cu neurotoxicity by attenuating oxidative injury, inflammatory response, and apoptosis and upregulating AKT/GSK-3β signaling. The neuroprotective effect of N-CUR was more potent than CUR.

Tobacco smoking induces metabolic reprogramming of renal cell carcinoma

BACKGROUNDClear cell renal cell carcinoma (ccRCC) is the most common histologically defined renal cancer. However, it is not a uniform disease and includes several genetic subtypes with different prognoses. ccRCC is also characterized by distinctive metabolic reprogramming. Tobacco smoking (TS) is an established risk factor for ccRCC, with unknown effects on tumor pathobiology.METHODSWe investigated the landscape of ccRCCs and paired normal kidney tissues using integrated transcriptomic, metabolomic, and metallomic approaches in a cohort of white males who were long-term current smokers (LTS) or were never smokers (NS).RESULTSAll 3 Omics domains consistently identified a distinct metabolic subtype of ccRCCs in LTS, characterized by activation of oxidative phosphorylation (OXPHOS) coupled with reprogramming of the malate-aspartate shuttle and metabolism of aspartate, glutamate, glutamine, and histidine. Cadmium, copper, and inorganic arsenic accumulated in LTS tumors, showing redistribution among intracellular pools, including relocation of copper into the cytochrome c oxidase complex. A gene expression signature based on the LTS metabolic subtype provided prognostic stratification of The Cancer Genome Atlas ccRCC tumors that was independent of genomic alterations.CONCLUSIONThe work identified the TS-related metabolic subtype of ccRCC with vulnerabilities that can be exploited for precision medicine approaches targeting metabolic pathways. The results provided rationale for the development of metabolic biomarkers with diagnostic and prognostic applications using evaluation of OXPHOS status. The metallomic analysis revealed the role of disrupted metal homeostasis in ccRCC, highlighting the importance of studying effects of metals from e-cigarettes and environmental exposures.FUNDINGDepartment of Defense, Veteran Administration, NIH, ACS, and University of Cincinnati Cancer Institute.

Nano-Curcumin Prevents Cardiac Injury, Oxidative Stress and Inflammation, and Modulates TLR4/NF-κB and MAPK Signaling in Copper Sulfate-Intoxicated Rats

Copper (Cu) is essential for a plethora of biological processes; however, its high redox reactivity renders it potentially toxic. This study investigated the protective effect of curcumin (CUR) and nano-CUR (N-CUR) against Cu cardiotoxicity, emphasizing the role of oxidative stress, TLR4/NF-κB and mitogen-activated protein kinase (MAPK) signaling and cell death in rats. Rats received 100 mg/kg copper sulfate (CuSO₄), a pesticide used for repelling pests, and were concurrently treated with CUR or N-CUR for 7 days. Cu caused cardiac injury manifested by elevated serum cardiac troponin I (cTnI), creatine kinase (CK)-MB, and lactate dehydrogenase (LDH), as well as histopathological alterations. Cardiac malondialdehyde (MDA), NF-κB p65, TNF-α, and IL-6 were increased, and reduced glutathione (GSH), superoxide dismutase (SOD) and catalase were decreased in Cu-treated rats. CUR and N-CUR prevented cardiac tissue injury, decreased serum cTnI, CK-MB, and LDH, and cardiac MDA, NF-κB p65, TNF-α, and IL-6, and enhanced cellular antioxidants. CUR and N-CUR downregulated TLR4 and AP-1, and decreased the phosphorylation levels of p38 MAPK, JNK, and ERK1/2. In addition, CUR and N-CUR increased cardiac Bcl-2 and BAG-1, decreased Bax and caspase-3, and prevented DNA fragmentation. In conclusion, N-CUR prevents Cu cardiotoxicity by attenuating oxidative injury, inflammatory response, and apoptosis, and modulating TLR4/NF-κB and MAPK signaling. The cardioprotective effect of N-CUR was more potent than the native form.

Estrone-salicylaldehyde N-methylated thiosemicarbazone hybrids and their copper complexes: solution structure, stability and anticancer activity in tumour spheroids

The terminal N-mono- and dimethylated derivatives of an estrone-salicylaldehyde thiosemicarbazone hybrid and their highly cytotoxic Cu(II) complexes were synthesized and characterized in addition to their structurally related simpler bicyclic analogues. Solution stability and structure of the complexes were determined by UV-visible spectrophotometry and electron paramagnetic resonance spectroscopy. The monomethylation has a minor influence on the pK_a values, while the dimethylation results in somewhat more acidic derivatives compared to the non-methylated derivatives, although all the compounds are neutral at physiological pH. Based on the speciation studies performed in a 30% (v/v) dimethyl sulfoxide/water mixture, the four novel ligands form fairly high-stability complexes with Cu(II) ions, in which they coordinate in mono-anionic (O^‒,N,S) or di-anionic (O^‒,N,S^‒) binding modes. [CuLH_‒1] species with (O^‒,N,S^‒)(H₂O) coordination mode are present in solution at neutral pH, and these complexes were isolated and further studied. The Cu(II) complexes formed with the estrone hybrids were more stable in comparison with the bicyclic analogues. The terminal N-dimethylation results in the most stable complexes in a given ligand series. In vitro cytotoxicity of all the Cu(II) complexes was measured in 3D spheroids of HCT-116, A-549 and CH-1 human cancer cells which showed fairly low IC₅₀ values (3.9‒17.1 μM). The Cu(II) complexes caused reduced tumour growth, and they activated the caspase-3 and caspase-7 endoproteases leading to apoptosis except the case of the complex formed with the monomethylated bicyclic derivative, where other type of mechanisms of action seems to induce the cell death. Anticancer Cu(II) complexes of mono- and dimethylated salicylaldehyde thiosemicarbazone-estrone hybrids possessing high solution stability and strong cytotoxic effect against 3D spheroids of a series of human cancer cells. 398x273 mm (150 x 150 DPI).

The molecular and cellular basis of copper dysregulation and its relationship with human pathologies

Copper (Cu) is an essential micronutrient required for the activity of redox-active enzymes involved in critical metabolic reactions, signaling pathways, and biological functions. Transporters and chaperones control Cu ion levels and bioavailability to ensure proper subcellular and systemic Cu distribution. Intensive research has focused on understanding how mammalian cells maintain Cu homeostasis, and how molecular signals coordinate Cu acquisition and storage within organs. In humans, mutations of genes that regulate Cu homeostasis or facilitate interactions with Cu ions lead to numerous pathologic conditions. Malfunctions of the Cu⁺ -transporting ATPases ATP7A and ATP7B cause Menkes disease and Wilson disease, respectively. Additionally, defects in the mitochondrial and cellular distributions and homeostasis of Cu lead to severe neurodegenerative conditions, mitochondrial myopathies, and metabolic diseases. Cu has a dual nature in carcinogenesis as a promotor of tumor growth and an inducer of redox stress in cancer cells. Cu also plays role in cancer treatment as a component of drugs and a regulator of drug sensitivity and uptake. In this review, we provide an overview of the current knowledge of Cu metabolism and transport and its relation to various human pathologies.

The Relationship between Serum Trace Elements and Oxidative Stress of Patients with Different Types of Cancer

Objective

Many studies have identified causal and promotive roles of oxidative stress (OxS) and oxidative damage caused by OxS in the occurrence and progression of cancer. Many biomarkers in the blood circulation of patients may change correspondingly with the development of tumors. This study is aimed at investigating the correlation between OxS and serum trace element (TE) levels of patients with different types of cancer.

Methods

1143 different types of cancer patients and 178 healthy controls from Mar. 2018 to Aug. 2020 in Mianyang Central Hospital were involved in this study. Their levels of OxS parameters (including total oxidant status (TOS), total antioxidant status (TAS), and oxidant stress index (OSI)) and the concentrations of serum TEs (including Cu, Zn, Fe, and Se) were determined.

Results

Compared with healthy controls, all types of cancer patients had higher TOS level (all P_adj < 0.001) and OSI level (z = 6.228 ~ 9.909, all P_adj < 0.001) and lower TAS level (all P_adj < 0.001). Compared with healthy controls, the changes of four TE levels in serum were different in different types of cancer patients, among which Cu increased in all groups, but there was no statistical difference in gastric and brain cancer; Se decreased in all groups, but there was no statistical difference in gastric, colorectal, esophageal, and other cancer; Zn was significantly decreased in breast cancer patients (P_adj < 0.001); there was no statistical difference in the change of Fe in liver, kidney, and other cancer. Spearman correlation showed that the change of Cu concentration was most closely related to the three OxS parameters and was strongly correlated in the observed several types of tumors (r_s > 0.6). Multinomial logistic regression showed that the risks of different tumors are related to the level change of multiple TEs and OxS parameters (OR_TOS = 1.19 ~ 2.82, OR_OSI = 2.56 ~ 4.70, OR_TAS = 0.20 ~ 0.46, OR_Cu = 0.73 ~ 1.44, OR_Zn = 0.81 ~ 0.91, OR_Fe = 0.68 ~ 1.18, and OR_Se = 0.22 ~ 0.45, all P < 0.006).

Conclusions

The OxS exists in the occurrence and development of cancer, which may be related to the changes of certain trace elements. In order to evaluate OxS correctly, it is necessary to detect TAS and TOS and at the same time, their ratio OSI should be detected. Assessment of markers representing the overall level of OxS and TEs may guarantee improved the monitoring of disease occurrence and development risk in cancer patients.

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.

From solid state to in vitro anticancer activity of copper(II) compounds with electronically-modulated NNO Schiff base ligands

The copper(ii) complexes of general formula [Cu(GL)(Cl)] (1-3, G = OMe, H and NO2, respectively), bearing tridentate Schiff base ligands (GL-) and a chloride as a fourth labile one, are here reported. The Schiff bases derive from the monocondensation of ethylenediamine and substituted salicylaldehyde, where the electronic properties are modulated by the releasing or withdrawing power of the G group. The compounds were structurally characterized through single crystal Synchrotron X-ray diffraction experiments in the solid state, revealing that 1 (OMe) and 2 (H) adopt a dimeric assembly [Cu(μ-Cl)(GL)]2 through apical interaction of the chloride ions of two monomeric units, while 3 embraces a 1D polymeric chain structure [Cu(μ-Cl)(NO2L)]n with a similar bridging fashion, all supported by extended intramolecular or intrachain hydrogen bonds. The redox properties of the complexes were also studied by cyclic voltammetry with no marked effect of the substituent on the potential of the CuII/CuI redox system. UV/Vis spectroscopic studies in mimicked physiological conditions highlighted the intactness and stability of the coordinated NNO tridentate ligand in 1-3 and the lability of the coordinated chloride ion with the formation of the aquo-complexes [Cu(GL)(H2O)]+ in aqueous solution, as confirmed by conductance measurements with a 1 : 1 electrolyte molar conductivity. In vitro tests on cell viability were conducted on malignant cell lines typical for their poor prognosis and curability, revealing time-dependent and differential cytotoxicity given by the substituent G. All compounds were capable of formation of intracellular reactive oxygen species and DNA intercalation, acting as nuclease and producing double-strand DNA breaks. This is especially effective for 3 (NO2), which revealed the highest anticancer activity against malignant triple-negative breast cancer MDA-MB-231 cells, with a two-to-four-fold cytotoxicity enhancement with respect to 1 (OMe) and 2 (H), and, most important, substantial differentiation of cytotoxicity with respect to healthy endothelial HUVEC cell line.

Structure prediction of neutral physiological copper(II) compounds with l-cysteine and l-histidine

Bis(aminoacidato)copper(II) [Cu^II(aa)₂] coordination compounds are the physiological species of copper(II) amino acid compounds in blood plasma. Since there are no experimental data in the literature about the geometries that physiological Cu^II(aa)₂ could form with l-cysteine (Cys), that is, for bis(l-cysteinato)copper(II) [Cu(Cys)₂] and the ternary (l-histidinato)(l-cysteinato)copper(II) [Cu(His)(Cys)], this paper computationally examines the possible conformations that the two compounds could form with the Cys ligand having a protonated sulfur, as in the conventional zwitterion, which was determined to be prevailing in aqueous solution. These two amino acids can bind metals in a tridentate fashion and thus form many possible coordination patterns. Density functional calculations were performed for the conformational analyses in the gas phase and in implicitly modeled aqueous solution using a polarizable continuum model. Additionally, we examine which coordination mode, with thiol or thiolate group, is more stable. The Cys coordination via the amino N and carboxylato O atoms (a glycinato mode) is obtained as the most stable one in aqueous Cu(Cys)₂, and also in Cu(His)(Cys) when the His glycinato or histaminato mode combines with the intact thiol group. Whereas the conformers with N and thiol S as the copper(II) donor atoms are predicted to be the least stable, those with the Cu-N and Cu-S(thiolate) bonding (and protonated carboxylato group) are the most stable. The differences are explained by different covalent and ionic contributions of Cu-S(thiol) vs. Cu-S(thiolate). The study can contribute to the insight into formation and reactivity of the copper(II) cysteinato complexes in solution.

Ternary Copper (II) Complex Induced Apoptosis and Cell Cycle Arrest in Colorectal Cancer Cells

BACKGROUND

The lack of specificity, severe side effects, and development of drug resistance have largely limited the use of platinum-based compounds in cancer treatment. Therefore, copper complexes have emerged as potential alternatives to platinum-based compounds.

OBJECTIVE

Ternary copper (II) complex incorporated with 1-10-phenanthroline and L-tyrosine was investigated for its anti-cancer effects in HT-29 colorectal cancer cells.

METHODS

Cytotoxic effects of ternary copper (II) complex in HT-29 cells were evaluated using MTT assay, Real-Time Cell Analysis (RTCA), and lactate dehydrogenase (LDH) assay. Cell cycle analysis was performed using flow cytometry. Apoptosis induction was studied by Annexin V-FITC/propidium iodide (PI) staining and mitochondrial membrane potential analysis (JC-10 staining) using flow cytometry. Intracellular reactive oxygen species (ROS) were detected by DCFH-DA assay. The expression of proteins involved in the apoptotic signalling pathway (p53, caspases, and PARP-1) was evaluated by western blot analysis.

RESULTS

Ternary copper (II) complex reduced the cell viability of HT-29 cells in a time- and dose-dependent manner, with IC50 of 2.4 ± 0.4 and 0.8 ± 0.04 µM at 24 and 48 hours, respectively. Cell cycle analysis demonstrated induction of S-phase cell cycle arrest. Morphological evaluation and Annexin V-FITC/PI flow cytometry analysis confirmed induction of apoptosis that was further supported by cleavage and activation of caspase-8, caspase-9, caspase-3, and PARP-1. Mutant p53 was also downregulated in a dose-dependent manner. No LDH release, mitochondrial membrane potential disruption, and ROS production were observed.

CONCLUSION

Ternary copper (II) complex holds great potential to be developed for colorectal cancer treatment.

The Effects on Angiogenesis of Relevant Inorganic Chemotherapeutics

Angiogenesis is a key process allowing the formation of blood vessels. It is crucial for all the tissues and organs, ensuring their function and growth. Angiogenesis is finely controlled by several mechanisms involving complex interactions between pro- or antiangiogenic factors, and an imbalance in this control chain may result in pathological conditions. Metals as copper, zinc and iron cover an essential role in regulating angiogenesis, thus therapies having physiological metals as target have been proposed. In addition, some complexes of heavier metal ions (e.g., Pt, Au, Ru) are currently used as established or experimental anticancer agents targeting genomic or non-genomic targets. These molecules may affect the angiogenic mechanisms determining different effects that have been only poorly and non-systematically investigated so far. Accordingly, in this review article, we aim to recapitulate the impact on the angiogenic process of some reference anticancer drugs, and how it is connected to the overall pharmacological effects. In addition, we highlight how the activity of these drugs can be related to the role of biological essential metal ions. Overall, this may allow a deeper description and understanding of the antineoplastic activity of both approved or experimental metal complexes, providing important insights for the synthesis of new inorganic drugs able to overcome resistance and recurrence phenomena.

A modifiable risk factors atlas of lung cancer: A Mendelian randomization study

BACKGROUND

There has been no study systematically assessing the causal effects of putative modifiable risk factors on lung cancer. In this study, we aimed to construct a modifiable risk factors atlas of lung cancer by using the two-sample Mendelian randomization framework.

METHODS

We included 46 modifiable risk factors identified in previous studies. Traits with p-value smaller than 0.05 were considered as suggestive risk factors. While the Bonferroni corrected p-value for significant risk factors was set to be 8.33 × 10-4 .

RESULTS

In this two-sample Mendelian randomization analysis, we found that higher socioeconomic status was significantly correlated with lower risk of lung cancer, including years of schooling, college or university degree, and household income. While cigarettes smoked per day, time spent watching TV, polyunsaturated fatty acids, docosapentaenoic acid, eicosapentaenoic acid, and arachidonic acid in blood were significantly associated with higher risk of lung cancer. Suggestive risk factors for lung cancer were found to be serum vitamin A1, copper in blood, docosahexaenoic acid in blood, and body fat percentage.

CONCLUSIONS

This study provided the first Mendelian randomization assessment of the causality between previously reported risk factors and lung cancer risk. Several modifiable targets, concerning socioeconomic status, lifestyle, dietary, and obesity, should be taken into consideration for the development of primary prevention strategies for lung cancer.

A Self-Assembled Nanoindicator from Alizarin Red S-Borono-Peptide for Potential Imaging of Cellular Copper(II) Ions

Recently, smart nanomaterials from peptide self-assembly have received extensive attention in the field of biological and medical applications. Through rationally designing the molecular structure, we constructed a borono-peptide that self-assembled into well-defined nanofibers. Relying on the specific recognition between the vicinal diol compound and boronic acid, a novel alizarin red S (ARS)-borono-peptide (BP) spherical nanoindicator was fabricated, accompanying with the emission of strong fluorescent signal. The fluorescent nanoindicator displayed an intense response to copper(II) ions and underwent the fluorescent "turn-off" due to the strong binding-induced displacement. Originating from the high selectivity toward copper(II) ions, good biocompatibility and cancer cell targeting, the nanoindicator offered the opportunity to image copper(II) ions in cancer cells via fluorescent change.

The radioenhancement potential of Schiff base derived copper (II) compounds against lung carcinoma in vitro

For the last years, copper complexes have been intensively implicated in biomedical research as components of cancer treatment. Herewith, we provide highlights of the synthesis, physical measurements, structural characterization of the newly developed Cu(II) chelates of Schiff Bases, Cu(Picolinyl-L-Tryptopahanate)2, Cu(Picolinyl-L-Tyrosinate)2, Cu(Isonicotinyl-L-Tyrosinate)2, Cu(Picolinyl-L-Phenylalaninate)2, Cu(Nicotinyl-L-Phenylalaninate)2, Cu(Isonicotinyl-L-Phenylalaninate)2, and their radioenhancement capacity at kV and MV ranges of irradiation of human lung carcinoma epithelial cells in vitro. The methods of cell growth, viability and proliferation were used. All compounds exerted very potent radioenhancer capacities in the irradiated lung carcinoma cells at both kV and MV ranges in a 100 μM concentration. At a concentration of 10 μM, only Cu(Picolinyl-L-Tyrosinate)2, Cu(Isonicotinyl-L-Tyrosinate)2, Cu(Picolinyl-L-Phenylalaninate)2 possessed radioenhancer properties at kV and MV ranges. Cu(Picolinyl-L-Tryptophanate)2 showed radioenhancer properties only at kV range. Cu(Nicotinyl-L-Phenylalaninate)2 and Cu(Isonicotinyl-L-Phenylalaninate)2 showed remarkable radioenhancer activity only at MV range. All compounds acted in dose-dependent manner at both tested energy ranges. These copper (II) compounds, in combination with 1 Gy irradiation at either 120 kV or 6 MV, are more efficient at delaying cell growth of lung cancer cells and at reducing cell viability in vitro than the irradiation administered alone. Thus, we have demonstrated that the studied copper compounds have a good potential for radioenhancement.

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.

Efficacy and Safety of the 64Cu(II)Cl2 PET/CT for Urological Malignancies: Phase IIa Clinical Study

PURPOSE OF THE REPORT

The aim of this study was to evaluate safety and efficacy of copper-64(II)dichloride (64Cu(II)Cl2) as a new PET tracer for urological malignancies (UMs).

METHODS

Patients with UM were enrolled in a prospective study. All patients were staged with preoperative CT and 64Cu(II)Cl2 PET/CT. Patient characteristics, anatomical and functional imaging, and final histopathology were recorded. Surgical specimens for histopathological examination were collected. To determine time-activity curves for 64Cu(II)Cl2 uptake in UM and normal tissues, SUVs were calculated. The safety of 64Cu(II)Cl2 was assessed.

RESULTS

Twenty-three patients were included. An administered activity of 174.7 MBq (4.72 mCi) for 64Cu(II)Cl2 was equal to 9.80 mSv of the effective dose. The median SUVmax values were 5.7, 0.9, 1.8, and 9.8 for the prostate, bladder, penis, and kidney, respectively. Median SUVmax values were higher in organs with a malignancy in comparison with healthy tissue (prostate [11.5 vs 5.3, P < 0.001], bladder [6.2 vs 0.9, P = 0.007], and penis [3.9 vs 1.3, P = 0.027]), but not in the kidneys (5.0 vs 10.4, P = 0.998). The highest area under the curve (AUC) was reported for prostate cancer (AUC, 0.978), and the lowest for penile cancer (AUC, 0.775). The detection rates based on the best suggested cutoff according to the SUVmax were 85.7% (6/7) for prostate and bladder and 83.3% (5/6) for penile cancer. Neither drug-related effects nor physiologic responses occurred, nor adverse reactions.

CONCLUSIONS

64Cu(II)Cl2 is an effective and well-tolerated tracer in patients with UM. Our results show higher SUVmax in cancer patients than in healthy subjects. Our findings suggest that 64Cu(II)Cl2 PET/CT is useful in patients affected by prostate, bladder, and penis cancer.

Are trace element concentrations suitable biomarkers for the diagnosis of cancer?

Despite advances in cancer research, cancer is still one of the leading causes of death worldwide. An early diagnosis substantially increases the survival rate and treatment success. Thus, it is important to establish biomarkers which could reliably identify cancer patients. As cancer is associated with changes in the systemic trace element status and distribution, serum concentrations of selenium, iron, copper, and zinc could contribute to an early diagnosis. To test this hypothesis, case control studies measuring trace elements in cancer patients vs. matched controls were selected and discussed focusing on lung, prostate, breast, and colorectal cancer. Overall, cancer patients had elevated serum copper and diminished zinc levels, while selenium and iron did not show consistent changes for all four cancer types. Within the tumor tissue, mainly copper and selenium are accumulating. Whether these concentrations also predict the survival probability of cancer patients needs to be further investigated.

Identification METTL18 as a Potential Prognosis Biomarker and Associated With Immune Infiltrates in Hepatocellular Carcinoma

Methyltransferase-like 18 (METTL18), a METTL family member, is abundant in hepatocellular carcinoma (HCC). Studies have indicated the METTL family could regulate the progress of diverse malignancies while the role of METTL18 in HCC remains unclear. Data of HCC patients were acquired from the cancer genome atlas (TCGA) and gene expression omnibus (GEO). The expression level of METTL18 in HCC patients was compared with normal liver tissues by Wilcoxon test. Then, the logistic analysis was used to estimate the correlation between METTL18 and clinicopathological factors. Besides, Gene Ontology (GO), Gene Set Enrichment Analysis (GSEA), and single-sample Gene Set Enrichment Analysis (ssGSEA) were used to explore relevant functions and quantify the degree of immune infiltration for METTL18. Univariate and Multivariate Cox analyses and Kaplan-Meier analysis were used to estimate the association between METTL18 and prognosis. Besides, by cox multivariate analysis, a nomogram was conducted to forecast the influence of METTL18 on survival rates. METTL18-high was associated with Histologic grade, T stage, Pathologic stage, BMI, Adjacent hepatic tissue inflammation, AFP, Vascular invasion, and TP53 status (P < 0.05). HCC patients with METTL18-high had a poor Overall-Survival [OS; hazard ratio (HR): 1.87, P < 0.001), Disease-Specific Survival (DSS, HR: 1.76, P = 0.015), and Progression-Free Interval (PFI, HR: 1.51, P = 0.006). Multivariate analysis demonstrated that METTL18 was an independent factor for OS (HR: 2.093, P < 0.001), DSS (HR: 2.404, P = 0.015), and PFI (HR: 1.133, P = 0.006). Based on multivariate analysis, the calibration plots and C-indexes of nomograms showed an efficacious predictive effect for HCC patients. GSEA demonstrated that METTL18-high could activate G2M checkpoint, E2F targets, KRAS signaling pathway, and Mitotic Spindle. There was a positive association between the METTL18 and abundance of innate immunocytes (T helper 2 cells) and a negative relation to the abundance of adaptive immunocytes (Dendritic cells, Cytotoxic cells etc.). Finally, we uncovered knockdown of METTL18 significantly suppressed the proliferation, invasion, and migration of HCC cells in vitro. This research indicates that METTL18 could be a novel biomarker to evaluate HCC patients' prognosis and an important regulator of immune responses in HCC.

Therapeutic perspective of thiosemicarbazones derivatives in inflammatory pathologies: A summary of in vitro/in vivo studies

Following induction of inflammation, the nuclear factor kappa B (NF-κB) in activated macrophages induces the transcription of pro-inflammatory cytokines such as tumor necrosis factor-alpha (TNF-α), interleukin-1β (IL-1β), interleukin-6 (IL-6), and cyclooxygenase (COX), an inflammatory enzyme implicated in the synthesis of prostaglandins (PGs). The latter are involved in the transition and the maintenance of chronic inflammation underling various chronic disorders that require treatment. Concerning this, many anti-inflammatory drugs are available to treat the inflammatory disorders, but their therapeutic use is associated with a variety of side effects. Therefore, the discovery of new safer and potential anti-inflammatory drugs is necessary. In this regard, thiosemicarbazones (TSC) compounds and their metals complexes attracted high interest due to their wide range of biological activities, interestingly, the anti-inflammatory activity. They are formed by the action of thiosemicarbazide on an aldehyde or ketone, and contain a sulfur atom in place of the oxygen atom. Their ability to form a stable complex with transition metal is known to enhances the biological activity and reduces the side effects of the parent compound. Thus, this review article describes the inflammatory response mediated by NF-κB-COX-PGs and summarizes the anti-inflammatory activity of different thiosemicarbazones derivatives synthesized in research area.

Epithelial-mesenchymal transition and metastasis of colon cancer cells induced by the FAK pathway in cancer-associated fibroblasts

Objective

The role and mechanism of tetrathiomolybdate (TM) in cancer-associated fibroblasts (CAFs) in colon cancer using three-dimensional (3D) culture were investigated, and the associations between the focal adhesion kinase (FAK) pathway and epithelial–mesenchymal transition (EMT) in CAFs were explored.

Methods

A 3D co-culture model of colon cancer LOVO cells with CAFs and normal fibroblasts (NFs) was established using Matrigel as a scaffold material. The differential expression of LOXL2 (lysyl oxidase-like 2) in the supernatant of CAFs and NFs was determined using ELISA, and expression levels of EMT-related proteins and FAK signaling pathway-related proteins were determined using western blot.

Results

LOXL2 levels secreted by CAFs were higher compared with that secreted by NFs. In the CAF + LOVO group, compared with the LOVO group, E-cadherin expression decreased significantly, while N-cadherin and F-PAK expression increased significantly. TM results were opposite compared with the above results.

Conclusions

CAFs stimulate EMT in human colon cancer LOVO cells by secreting LOXL2 to activate the FAK signaling pathway, thereby promoting tumor metastasis. TM inhibited the occurrence of EMT in the CAF-induced colon cancer LOVO cell line, thereby reducing the invasion and metastasis of colon cancer cells.

Roles of Ion Fluxes, Metabolism, and Redox Balance in Cancer Therapy

Recent Advances: The 2019 Nobel Prize awarded to the mechanisms for oxygen sensing and adaptation according to oxygen availability, highlighting the fundamental importance of gaseous molecules. Gaseous molecules, including reactive oxygen species (ROS), can interact with different cations generated during metabolic and redox dysregulation in cancer cells. Cross talk between calcium signaling and metabolic/redox pathways leads to network-based dyregulation in cancer. Significance: Recent discovery on using small molecules targeting the ion channels, redox signaling, and protein modification on metabolic enzymes can effectively inhibit cancer growth. Several FDA-approved drugs and clinical trials are ongoing to target the calcium channels, such as TRPV6 and TRPM8. Multiple small molecules from natural products target metablic and redox enzymes to exert an anticancer effect. Critical Issues: Small molecules targeting key ion channels, metabolic enzymes that control key aspects of metabolism, and redox proteins are promising, but their action mechanisms of the target are needed to be elucidated with advanced-omic technologies, which can give network-based and highly dimensioal data. In addition, small molecules that can directly modify the protein residues have emerged as a novel anticancer strategy. Future Directions: Advanced technology accelerates the detection of ions and metabolic and redox changes in clinical samples for diagnosis and informs the decision of cancer treatment. The improvement of ROS detection, ROS target identification, and computational-aid drug discovery also improves clincal outcome.Overall, network-based or holistic regulations of cancer via ion therapy and metabolic and redox intervention are promising as new anticancer strategies. Antioxid. Redox Signal. 34, 1108-1127.

A Phase 1 dose-escalation study of disulfiram and copper gluconate in patients with advanced solid tumors involving the liver using S-glutathionylation as a biomarker

BACKGROUND

Disulfiram and metals inactivate key oncoproteins resulting in anti-neoplastic activity. The goal of this study was to determine the maximum tolerated dose of copper when administered with disulfiram in patients with advanced solid tumors and liver involvement.

METHODS

Disulfiram 250 mg was administered daily in 28-day cycles. Four doses of copper gluconate were tested (2, 4, 6, and 8 mg of elemental copper) in a standard 3 + 3 dose escalation design. Patients were evaluated for dose limiting toxicities and response. Protein S-glutathionylation was evaluated as a pharmacodynamic marker.

RESULTS

Twenty-one patients were enrolled and 16 patients were evaluable for dose limiting toxicities. Among the 21 patients, there was a median of 4 lines of prior chemotherapy. Five Grade 3 toxicities were observed (anorexia, elevated aspartate aminotransferase or AST, elevated alkaline phosphatase, fever, and fatigue). Response data was available for 15 patients. Four patients had stable disease with the longest duration of disease control being 116 days. The median duration of treatment for evaluable patients was 55 days (range 28-124). Reasons for discontinuation included functional decline, disease progression, and disease-associated death. Increased S-glutathionylation of serum proteins was observed with treatment.

CONCLUSION

Disulfiram 250 mg daily with copper gluconate (8 mg of elemental copper) was well-tolerated in patients with solid tumors involving the liver and was not associated with dose limiting toxicities. While temporary disease stabilization was noted in some patients, no objective responses were observed. Treatment was associated with an increase in S-glutathionylation suggesting that this combination could exert a suppressive effect on cellular growth and protein function.

TRIAL REGISTRATION

NCT00742911 , first posted 28/08/2008.

A luminescent ATCUN peptide variant with enhanced properties for copper(II) sensing in biological media

The measurement of labile Cu^II in biological samples is fundamental for understanding Cu metabolism and has been emerging as a promising diagnostic marker for Cu-related pathologies such as Wilson's and Alzheimer's diseases. The use of fluorescent chelators may be useful to circumvent separation steps employed by current methods. For this purpose, we recently designed a selective and suited-affinity turn-off luminescent probe based on a peptide bearing the Cu^II-binding Xxx-Zzz-His (Amino-Terminal Cu^II- and Ni^II-binding, ATCUN) motif and a Tb^III-DOTA (1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid) complex. Here, we present an analogue probe bearing the ATCUN motif variant Xxx-His-His. This probe showed much faster response in biologically-relevant media and higher stability than the previous motif at low pH. These features could be beneficial to the measurement of dynamic Cu^II fluctuations and the application in slightly acidic media, such as urine.

Thiosemicarbazone(s)-anchored water soluble mono- and bimetallic Cu(ii) complexes: enzyme-like activities, biomolecular interactions, anticancer property and real-time live cytotoxicity

The reactions of CuCl2·2H2O with chromone thiosemicarbazone ligands containing a -H or -CH3 substituent on terminal N yielded monometallic Cu(ii) complexes [Cu(HL1)Cl2] (1) and [Cu(HL2)Cl2] (2), whereas bimetallic Cu(ii) complexes [Cu(μ-Cl)(HL3)]2Cl2 (3), [Cu(μ-Cl)(HL4)]2Cl2 (4) and [Cu(μ-Cl)(L5)]2 (5) were obtained when a -C2H5, -C6H11 or -C6H5 substituent was present, respectively, in the ligands. The complexes were characterized using elemental analyses, UV-Vis, FT-IR, EPR, mass and TGA studies. The structures of neutral monometallic and dicationic bimetallic complexes were confirmed by single crystal X-ray diffraction, and they exhibited a distorted square pyramidal geometry around Cu(ii) ions. The catecholase-mimicking activity of complexes 1-5 was examined spectrophotometrically, and the results revealed that all the complexes except 5 had the ability to oxidize 3,5-di-tert-butylcatechol (3,5-DTBC) to 3,5-di-tert-butylquinone (3,5-DTBQ) under aerobic conditions with moderate turnover numbers. In order to find the possible complex-substrate intermediates, a mass spectrometry study was carried out for complexes 1-4 in the presence of 3,5-DTBC. The phosphatase-like activity of 1-5 was also investigated using 4-nitrophenylphosphate (4-NPP) as a model substrate. All the complexes exhibited excellent phosphatase activity in DMF-H2O medium. The complexes displayed significant biomolecular interactions and antioxidant potential. Complex 3 showed good interaction with apoptotic CASP3 protein, VEGFR2 and PIM-1 kinase receptors as revealed by a molecular docking study. Complexes (3-5) exhibited promising cytotoxicity against HeLa-cervical cancer cells with IC50 values of 2.24 (3), 2.25 (4) and 3.77 (5) μM, respectively, and showed a two-fold higher activity than cisplatin. The active complex 3 showed complete inhibition of colony formation at 10 μM concentration. In addition, the acridine orange (AO)/ethidium bromide (EB) staining and real-time live cell imaging results confirmed that complex 3 induced cell death in HeLa cells.

Update on Osteosarcoma

PURPOSE OF REVIEW

Osteosarcoma (OSA) is the most common primary tumor of bone, mainly affecting children and adolescents. Here we discuss recent advances in surgical and systemic therapies, and highlight potentially new modalities in preclinical evaluation and prognostication.

RECENT FINDINGS

The advent of neoadjuvant and adjuvant chemotherapy has markedly improved the disease-free recurrence and overall survival of OSA. However, treatment efficacy has been stagnant since the 1980s. This plateau has prompted preclinical and clinical research into in precision surgery, inhaled chemotherapy to increase pulmonary drug concentration without systemic side effects, and novel immunomodulators intended to block molecular pathways associated with OSA proliferation and metastasis. With the advent of novel surgical techniques and new forms and vectors for chemotherapy, it is hoped that OSA treatment outcomes will exceed their currently sustained plateau in the near future.

Targeting Ubiquitin-Proteasome System With Copper Complexes for Cancer Therapy

Characterizing mechanisms of protein homeostasis, a process of balancing between protein synthesis and protein degradation, is important for understanding the potential causes of human diseases. The ubiquitin–proteasome system (UPS) is a well-studied mechanism of protein catabolism, which is responsible for eliminating misfolded, damaged, or aging proteins, thereby maintaining quality and quantity of cellular proteins. The UPS is composed of multiple components, including a series of enzymes (E1, E2, E3, and deubiquitinase [DUB]) and 26S proteasome (19S regulatory particles + 20S core particle). An impaired UPS pathway is involved in multiple diseases, including cancer. Several proteasome inhibitors, such as bortezomib, carfilzomib, and ixazomib, are approved to treat patients with certain cancers. However, their applications are limited by side effects, drug resistance, and drug–drug interactions observed in their clinical processes. To overcome these shortcomings, alternative UPS inhibitors have been searched for in many fields. Copper complexes (e.g., CuET, CuHQ, CuCQ, CuPDTC, CuPT, and CuHK) are found to be able to inhibit a core component of the UPS machinery, such as 20S proteasome, 19S DUBs, and NPLOC4/NPL4 complex, and are proposed to be one class of metal-based anticancer drugs. In this review, we will summarize functions and applications of copper complexes in a concise perspective, with a focus on connections between the UPS and cancer.

Monotherapy and Combination Therapy Using Anti-Angiogenic Nanoagents to Fight Cancer

Anti-angiogenic therapy, targeting vascular endothelial cells (ECs) to prevent tumor growth, has been attracting increasing attention in recent years, beginning with bevacizumab (Avastin) through its Phase II/III clinical trials on solid tumors. However, these trials showed only modest clinical efficiency; moreover, anti-angiogenic therapy may induce acquired resistance to the drugs employed. Combining advanced drug delivery techniques (e.g., nanotechnology) or other therapeutic strategies (e.g., chemotherapy, radiotherapy, phototherapy, and immunotherapy) with anti-angiogenic therapy results in significantly synergistic effects and has opened a new horizon in fighting cancer. Herein, clinical difficulties in using traditional anti-angiogenic therapy are discussed. Then, several promising applications of anti-angiogenic nanoagents in monotherapies and combination therapies are highlighted. Finally, the challenges and perspectives of anti-angiogenic cancer therapy are summarized. A useful introduction to anti-angiogenic strategies, which may significantly improve therapeutic outcomes, is thus provided.

Biological activities of polypyridyl-type ligands: implications for bioinorganic chemistry and light-activated metal complexes

Polypyridyl coordinating ligands are common in metal complexes used in medicinal inorganic chemistry. These ligands possess intrinsic cytotoxicity, but detailed data on this phenomenon are sparse, and cytotoxicity values vary widely and are often irreproducible. To provide new insights into the biological effects of bipyridyl-type ligands and structurally related metal-binding systems, reports of free ligand cytotoxicity were reviewed. The cytotoxicity of 25 derivatives of 2,2'-bipyridine and 1,10-phenanthroline demonstrates that there is no correlation between IC₅₀ values and ligand properties such as pKa, log D, polarizability volume, and electron density, as indicated by NMR shifts. As a result of these observations, as well as the various reported mechanisms of action of polypyridyl ligands, we offer the hypothesis that biological effects are governed by the availability of and affinity for specific metal ions within the experimental model.

Bioactive Tryptophan-Based Copper Complex with Auxiliary β-Carboline Spectacle Potential on Human Breast Cancer Cells: In Vitro and In Vivo Studies

Biocompatible tryptophan-derived copper (1) and zinc (2) complexes with norharmane (β-carboline) were designed, synthesized, characterized, and evaluated for the potential anticancer activity in vitro and in vivo. The in vitro cytotoxicity of both complexes 1 and 2 were assessed against two cancerous cells: (human breast cancer) MCF7 and (liver hepatocellular cancer) HepG2 cells with a non-tumorigenic: (human embryonic kidney) HEK293 cells. The results exhibited a potentially decent selectivity of 1 against MCF7 cells with an IC50 value of 7.8 ± 0.4 μM compared to 2 (less active, IC50 ~ 20 μM). Furthermore, we analyzed the level of glutathione, lipid peroxidation, and visualized ROS generation to get an insight into the mechanistic pathway and witnessed oxidative stress. These in vitro results were ascertained by in vivo experiments, which also supported the free radical-mediated oxidative stress. The comet assay confirmed the oxidative stress that leads to DNA damage. The histopathology of the liver also ascertained the low toxicity of 1.

Novel Copper(II) Complex with a 4-Acylpyrazolone Derivative and Coligand Induce Apoptosis in Liver Cancer Cells

A novel pyrazolone-based copper complex [CuL(phen)(CH₃OH)][CuL(phen)]·CH₃CH₂OH·CH₃OH (P-FAH-Cu-phen) was synthesized and characterized. The asymmetric structural unit of P-FAH-Cu-phen was composed of two independent complex units [CuL(phen)(CH₃OH)] and [CuL(phen)]:Cu1²⁺ center with six coordination mode and Cu2²⁺ center with five coordination mode. The growth of BEL-7404 cells and H22 cells was significantly inhibited by P-FAH-Cu-phen with IC₅₀ values of 1.175 μg/mL and 1.097 μg/mL, respectively, which were much lower than IC₅₀ of cisplatin for BEL-7404 cells (23.32 μg/mL) and H22 cells (27.5 μg/mL). P-FAH-Cu-phen induced cell cycle arrest at G2/M and apoptosis in BEL-7404 cells through mitochondria- and endoplasmic reticulum stress-associated pathways. Moreover, P-FAH-Cu-phen significantly suppressed the migration of BEL-7404 cells and the tumor growth in H22 tumor mouse model without severe side effects and improved the survival of tumor mice. The results suggested that P-FAH-Cu-phen might be a potential drug candidate for the treatment of live cancer.

Biocompatibility of nanomaterials and their immunological properties

Nanomaterials (NMs) have revolutionized multiple aspects of medicine by enabling novel sensing, diagnostic, and therapeutic approaches. Advancements in processing and fabrication have also allowed significant expansion in the applications of the major classes of NMs based on polymer, metal/metal oxide, carbon, liposome, or multi-scale macro-nano bulk materials. Concomitantly, concerns regarding the nanotoxicity and overall biocompatibility of NMs have been raised. These involve putative negative effects on both patients and those subjected to occupational exposure during manufacturing. In this review, we describe the current state of testing of NMs including those that are in clinical use, in clinical trials, or under development. We also discuss the cellular and molecular interactions that dictate their toxicity and biocompatibility. Specifically, we focus on the reciprocal interactions between NMs and host proteins, lipids, and sugars and how these induce responses in immune and other cell types leading to topical and/or systemic effects.

Mitochondrial copper depletion suppresses triple-negative breast cancer in mice

Depletion of mitochondrial copper, which shifts metabolism from respiration to glycolysis and reduces energy production, is known to be effective against cancer types that depend on oxidative phosphorylation. However, existing copper chelators are too toxic or ineffective for cancer treatment. Here we develop a safe, mitochondria-targeted, copper-depleting nanoparticle (CDN) and test it against triple-negative breast cancer (TNBC). We show that CDNs decrease oxygen consumption and oxidative phosphorylation, cause a metabolic switch to glycolysis and reduce ATP production in TNBC cells. This energy deficiency, together with compromised mitochondrial membrane potential and elevated oxidative stress, results in apoptosis. CDNs should be less toxic than existing copper chelators because they favorably deprive copper in the mitochondria in cancer cells instead of systemic depletion. Indeed, we demonstrate low toxicity of CDNs in healthy mice. In three mouse models of TNBC, CDN administration inhibits tumor growth and substantially improves survival. The efficacy and safety of CDNs suggest the potential clinical relevance of this approach.

Study of Essential and Toxic Metal Imbalances in the Scalp Hair of Thyroid Cancer Patients in Comparison with Healthy Donors

Thyroid cancer is among the most common type of head and neck cancer; diet, age, gender and environmental factors play vital roles in its malignancy. The present study was carried out to assess the imbalances in the contents of trace metals due to onset and progression of thyroid cancer. Scalp hair was used as matrix for the evaluation of toxic and trace metals. Quantification of the metals was done through atomic absorption spectrometry. In comparison with healthy subjects, the thyroid cancer patients revealed significantly higher median levels of Mn (71%), Co (64%), Cr (55%), K (49%), Fe (45%), Mg (42%), Pb (36%), Na (30%), and Ni (26%), while the median level of Zn was considerably lower in the patients. The correlation coefficients among the metals in the patients demonstrated significantly different communal relationships compared with the healthy counterparts. Multivariate methods exhibited noticeably dissimilar apportionment among the metals in the patients than the controls. Significant disparities in the metal levels were also noticed for various types (anaplastic thyroid cancer, follicular thyroid cancer, papillary thyroid cancer, and medullary thyroid cancer) as well as stages (I, II, III, and IV) among the thyroid cancer patients. Majority of the metals revealed perceptible disparities in their contents based on gender, habitat, dietary habits, and smoking habits of the patients and controls. Overall, the study showed significantly divergent distribution and associations of the essential and toxic metal levels in the scalp hair of the patients in comparison with the levels in controls.