Therapeutic applications of gold complexes: lipophilic gold(III) cations and gold(I) complexes for anti-cancer treatment

Anticancer Activity of Metallodrugs and Metallizing Host Defense Peptides-Current Developments in Structure-Activity Relationship

This article provides an overview of the development, structure and activity of various metal complexes with anti-cancer activity. Chemical researchers continue to work on the development and synthesis of new molecules that could act as anti-tumor drugs to achieve more favorable therapies. It is therefore important to have information about the various chemotherapeutic substances and their mode of action. This review focuses on metallodrugs that contain a metal as a key structural fragment, with cisplatin paving the way for their chemotherapeutic application. The text also looks at ruthenium complexes, including the therapeutic applications of phosphorescent ruthenium(II) complexes, emphasizing their dual role in therapy and diagnostics. In addition, the antitumor activities of titanium and gold derivatives, their side effects, and ongoing research to improve their efficacy and reduce adverse effects are discussed. Metallization of host defense peptides (HDPs) with various metal ions is also highlighted as a strategy that significantly enhances their anticancer activity by broadening their mechanisms of action.

Harnessing the power of gold: advancements in anticancer gold complexes and their functionalized nanoparticles

Cancer poses a formidable challenge, necessitating improved treatment strategies. Metal-based drugs and nanotechnology offer new hope in this battle. Versatile gold complexes and functionalized gold nanoparticles exhibit unique properties like biologically inert behaviour, outstanding light absorption, and heat-conversion abilities. These nanoparticles can be finely tuned for drug delivery, enabling precise and targeted cancer therapy. Their exceptional drug-loading capacity and low toxicity, stemming from excellent stability, biocompatibility, and customizable shapes, make them a promising option for enhancing cancer treatment outcomes and improving diagnostic imaging. Leveraging these attributes, researchers can design more effective and targeted cancer therapeutics. The potential of functionalized gold nanoparticles to advance cancer treatment and diagnostics holds a promising avenue for further exploration and development in the fight against cancer. This review article delves into the finely tuned attributes of functionalized gold nanoparticles, unveiling their potential for application in drug delivery for precise and targeted cancer therapy.

Organogold(III)-dithiocarbamate compounds and their coordination analogues as anti-tumor and anti-leishmanial metallodrugs

The limited chemical stability of gold(III)-based compounds in physiological environment has been a challenge in drug discovery, and organometallic chemistry might provide the solution to overcome this issue. In this work, four novel cationic organogold(III)-dithiocarbamate complexes of general structure [(C^N)AuIIIDTC]PF6 (C1a - C4a, DTC = dithiocarbamate, L1 - L4, C^N = 2-anilinopyridine) are presented, and compared to their coordination gold(III)-dithiocarbamate analogues [AuIIIDTCCl2] (C1b - C4b), as potential anti-cancer and anti-leishmanial drugs. Most of the complexes effectively inhibited cancer cell growth, notably C3a presented anti-proliferative effect in the nanomolar range against breast cancer (MCF-7 and MDA-MB-231 cells with moderate selectivity. Pro-apoptotic studies on treated MCF-7 cells showed a high population of cells in early apoptosis. Reactivity studies of C3a towards model thiols (N-acetyl-L-cysteine) refer to a possible mode of action involving bonding between the organogold(III)-core and the thiolate. In the scope of neglected diseases, gold complexes are emerging as promising therapeutic alternatives against leishmaniasis. In this regard, all gold(III)-dithiocarbamate complexes presented anti-leishmanial activity against at least one Leishmania species. Complexes C1a, C4a, C1b, C4b were active against all tested parasites with IC50 values varying between 0.12 and 42 μM, and, overall, organometallic compounds presented more intriguing inhibition profiles. For C4a selectivity over 500-fold for L. braziliensis; even higher than the reference anti-leishmanial drug amphotericin B. Overall, our findings revealed that the organogold(III) moiety significantly amplified the anti-cancer and anti-leishmanial effects with respect to the coordination analogues; thus, showing the great potential of organometallic chemistry in metallodrug-based chemotherapy for cancer and leishmaniasis.

Catalysis-free synthesis of thiazolidine-thiourea ligands for metal coordination (Au and Ag) and preliminary cytotoxic studies

The reaction of propargylamines with isothiocyanates results in the selective formation of iminothiazolidines, aminothiazolines or mixed thiazolidine-thiourea compounds under mild conditions. It has been observed that secondary propargylamines lead to the selective formation of cyclic 2-amino-2-thiazoline derivatives, while primary propargylamines form iminothiazoline species. In addition, these cyclic thiazoline derivatives can further react with an excess of isothiocyanate to give rise to thiazolidine-thiourea compounds. These species can also be achieved by reaction of propargylamines with isothiocynates in a molar ratio of 1 : 2. Coordination studies of these heterocyclic species towards silver and gold with different stoichiometries have been carried out and complexes of the type [ML(PPh₃)]OTf, [ML₂]OTf (M = Ag, Au) or [Au(C₆F₅)L] have been synthesised. Preliminary studies of the cytotoxic activity in lung cancer cells have also been performed in both ligands and complexes, showing that although the ligands do not exhibit anticancer activity, their coordination to metals, especially silver, greatly enhances the cytotoxic activity.

Recent Trends in the Development of Novel Metal-Based Antineoplastic Drugs

Since the accidental discovery of the anticancer properties of cisplatin more than half a century ago, significant efforts by the broad scientific community have been and are currently being invested into the search for metal complexes with antitumor activity. Coordination compounds of transition metals such as platinum (Pt), ruthenium (Ru) and gold (Au) have proven their effectiveness as diagnostic and/or antiproliferative agents. In recent years, experimental work on the potential applications of elements including lanthanum (La) and the post-transition metal gallium (Ga) in the field of oncology has been gaining traction. The authors of the present review article aim to help the reader "catch up" with some of the latest developments in the vast subject of coordination compounds in oncology. Herewith is offered a review of the published scientific literature on anticancer coordination compounds of Pt, Ru, Au, Ga and La that has been released over the past three years with the hope readers find the following article informative and helpful.

Recent Advances in the Discovery of Therapeutics to Curtail Islet Amyloid Polypeptide Aggregation for Type 2 Diabetes Treatment

In humans with type 2 diabetes, at least 70% of patients exhibit islet amyloid plaques formed by misfolding islet amyloid polypeptides (IAPP). The oligomeric conformation and accumulation of the IAPP plaques lead to a panoply of cytotoxic effects on the islet β-cells. Currently, no marketed therapies for the prevention or elimination of these amyloid deposits exist, and therefore significant efforts are required to address this gap. To date, most of the experimental treatments are limited to only in vitro stages of testing. In general, the proposed therapeutics use various targeting strategies, such as binding to the N-terminal region of islet amyloid polypeptide on residues 1-19 or the hydrophobic region of IAPP. Other strategies include targeting the peptide self-assembly through π-stacking. These methods are realized by using several different families of compounds, four of which are highlighted in this review: naturally occurring products, small molecules, organometallic compounds, and nanoparticles. Each of these categories holds immense potential to optimize and develop inhibitor(s) of pancreatic amyloidosis in the near future.

Materials for restoring lost Activity: Old drugs for new bugs

The escalation of bacterial resistance to conventional medical antibiotics is a serious concern worldwide. Improvements to current therapies are urgently needed to address this problem. The synergistic combination of antibiotics with other agents is a strategic solution to combat multi-drug-resistant bacteria. Although these combinations decrease the required high dosages and therefore, reduce the toxicity of both agents without compromising the bactericidal effect, they cannot stop the development of further resistance. Recent studies have shown certain elements restore the ability of antibiotics to destroy bacteria that have acquired resistance to them. Due to these synergistic activities, organic and inorganic molecules have been investigated with the goal of restoring antibiotics in new approaches that mitigate the risk of expanding resistance. Herein, we summarize recent studies that restore antibiotics once thought to be ineffective, but have returned to our armamentarium through innovative, combinatorial efforts. A special focus is placed on the mechanisms that allow the synergistic combinations to combat bacteria. The promising data that demonstrated restoration of antimicrobials, supports the notion to find more combinations that can combat antibiotic-resistant bacteria.

Ligand-enabled oxidation of gold(i) complexes with o-quinones

Chelating P^P and hemilabile P^N ligands were found to trigger the oxidation of Au(i) complexes by o-benzoquinones. The ensuing Au(iii) catecholate complexes have been characterized by NMR spectroscopy, single crystal X-ray diffraction and X-ray absorption spectroscopy. They adopt tetracoordinate square-planar structures. Reactivity studies substantiate the reversibility of the transformation. In particular, the addition of competing ligands such as chloride and alkenes gives back Au(i) complexes with concomitant release of the o-quinone. DFT calculations provide insight about the structure and relative stability of the Au(i) o-quinone and Au(iii) catecholate forms, and shed light on the 2-electron transfer from gold to the o-quinone.

Chelating P^P and hemilabile P^N ligands were found to trigger the oxidation of Au(i) complexes by o-benzoquinones.

Synthesis of New Thiourea-Metal Complexes with Promising Anticancer Properties

In this work, two thiourea ligands bearing a phosphine group in one arm and in the other a phenyl group (T2) or 3,5-di-CF₃ substituted phenyl ring (T1) have been prepared and their coordination to Au and Ag has been studied. A different behavior is observed for gold complexes, a linear geometry with coordination only to the phosphorus atom or an equilibrium between the linear and three-coordinated species is present, whereas for silver complexes the coordination of the ligand as P^S chelate is found. The thiourea ligands and their complexes were explored against different cancer cell lines (HeLa, A549, and Jurkat). The thiourea ligands do not exhibit relevant cytotoxicity in the tested cell lines and the coordination of a metal triggers excellent cytotoxic values in all cases. In general, data showed that gold complexes are more cytotoxic than the silver compounds with T1, in particular the complexes [AuT1(PPh₃)]OTf, the bis(thiourea) [Au(T1)₂]OTf and the gold-thiolate species [Au(SR)T1]. In contrast, with T2 better results are obtained with silver species [AgT1(PPh₃)]OTf and the [Ag(T1)₂]OTf. The role played by the ancillary ligand bound to the metal is important since it strongly affects the cytotoxic activity, being the bis(thiourea) complex the most active species. This study demonstrates that metal complexes derived from thiourea can be biologically active and these compounds are promising leads for further development as potential anticancer agents.

Synthetic Control of Mitochondrial Dynamics: Developing Three-Coordinate Au(I) Probes for Perturbation of Mitochondria Structure and Function

Mitochondrial structure and organization is integral to maintaining mitochondrial homeostasis and an emerging biological target in aging, inflammation, neurodegeneration, and cancer. The study of mitochondrial structure and its functional implications remains challenging in part because of the lack of available tools for direct engagement, particularly in a disease setting. Here, we report a gold-based approach to perturb mitochondrial structure in cancer cells. Specifically, the design and synthesis of a series of tricoordinate Au(I) complexes with systematic modifications to group 15 nonmetallic ligands establish structure-activity relationships (SAR) to identify physiologically relevant tools for mitochondrial perturbation. The optimized compound, AuTri-9 selectively disrupts breast cancer mitochondrial structure rapidly as observed by transmission electron microscopy with attendant effects on fusion and fission proteins. This phenomenon triggers severe depolarization of the mitochondrial membrane in cancer cells. The high in vivo tolerability of AuTri-9 in mice demonstrates its preclinical utility. This work provides a basis for rational design of gold-based agents to control mitochondrial structure and dynamics.

Multi-Targeted Anticancer Activity of Imidazolate Phosphane Gold(I) Compounds by Inhibition of DHFR and TrxR in Breast Cancer Cells

A class of phosphane gold(I) compounds, made of azoles and phosphane ligands, was evaluated for a screening on the regards of Breast Cancer cell panels (BC). The compounds possess N-Au-P or Cl-Au-P bonds around the central metal, and they differ for the presence of aprotic or protic polar groups in the azoles and/or the phosphane moieties to tune their hydrophilicity. Among the six candidates, only the compounds having the P-Au-N environment and not displaying neither the hydroxyl nor carboxyl groups in the ligands were found active. The compounds were screened by MTT tests in SKBR3, A17, and MDA-MB231 cancer cells, and two compounds (namely the 4,5-dicyano-imidazolate-1yl-gold(I)-(triphenylphosphane, 5, and 4,5-dichloro-imidazolate-1yl-gold(I)-triphenylphosphane, 6) were found very cytotoxic, with the most active with an IC₅₀ value of 3.46 μM in MDA-MB231 cells. By performing enzymatic assays in the treated cells lysates, the residual enzymatic activity of dihydrofolate reductase (DHFR) has been measured after cell treatment for 4 or 12 h in comparison with control cells. Upon 12 h of treatment, the activity of DHFR was significantly reduced in both SKBR3 and A17 cells by compounds 5 and 6, but not in human MDA-MB231 cells; interestingly, it was found remarkably high after 4 h of treatment, revealing a time dependence for the DHFR enzymatic assays. The DHFR inhibition data have been compared to those for the thioredoxin reductase (TrxR), the most recognized molecular target for gold compounds. For this latter, similar residual activities (i.e., 37 and 49% for the match of SKBR3 cells and compound 5 or 6, respectively) were found. Binding studies on the regards of ct-DNA (calf-thymus-DNA) and of plasma transporters proteins, such as BSA (bovine serum albumin) and ATF (apo transferrin), were performed. As expected for gold compounds, the data support strong binding to proteins (K_sv values range: 1.51 ÷ 2.46 × 10⁴ M⁻¹) and a weaker interaction with ct-DNA's minor groove (K_sv values range: 1.55 ÷ 6.12 × 10³ M⁻¹).

Multifunctional Microparticles Incorporating Gold Compound Inhibit Human Lung Cancer Xenograft

PURPOSE

Gold porphyrin (AuP) is a complex that has been shown to be potent against various tumors. A biocompatible interpenetrating network (IPN) system comprised of polyethyleneglycol diacrylate (PEGdA) and chemically-modified gelatin has been shown to be an effective implantable drug depot to deliver AuP locally. Here we designed IPN microparticles complexed with AuP to facilitate intravenous administration and to diminish systemic toxicity.

METHODS

We have synthesized and optimized an IPN microparticle formulation complexed with AuP. Tumor cell cytotoxicity, antitumor activity, and survival rate in lung cancer bearing nude mice were analyzed.

RESULTS

IPN microparticles maintained AuP bioactivity against lung cancer cells (NCI-H460). In vivo study showed no observable systemic toxicity in nude mice bearing NCI-H460 xenografts after intravenous injection of 6 mg/kg AuP formulated with IPN microparticles. An anti-tumor activity level comparable to free AuP was maintained. Mice treated with 6 mg/kg AuP in IPN microparticles showed 100% survival rate while the survival rate of mice treated with free AuP was much less. Furthermore, microparticle-formulated AuP significantly reduced the intratumoral microvasculature when compared with the control.

CONCLUSION

AuP in IPN microparticles can reduce the systemic toxicity of AuP without compromising its antitumor activity. This work highlighted the potential application of AuP in IPN microparticles for anticancer chemotherapy.

The Ca2+-ATPase Inhibition Potential of Gold(I, III) Compounds

The therapeutic applications of gold are well-known for many centuries. The most used gold compounds contain Au(I). Herein, we report, for the first time, the ability of four Au(I) and Au(III) complexes, namely dichloro (2-pyridinecarboxylate) Au(III) (abbreviated as 1), chlorotrimethylphosphine Au(I) (2), 1,3-bis(2,6-diisopropylphenyl) imidazole-2-ylidene Au(I) chloride (3), and chlorotriphenylphosphine Au(I) (4), to affect the sarcoplasmic reticulum (SR) Ca2+-ATPase activity. The tested gold compounds strongly inhibit the Ca2+-ATPase activity with different effects, being Au(I) compounds 2 and 4 the strongest, with half maximal inhibitory concentration (IC50) values of 0.8 and 0.9 µM, respectively. For Au(III) compound 1 and Au(I) compound 3, higher IC50 values are found (4.5 µM and 16.3 µM, respectively). The type of enzymatic inhibition is also different, with gold compounds 1 and 2 showing a non-competitive inhibition regarding the native substrate MgATP, whereas for Au compounds 3 and 4, a mixed type of inhibition is observed. Our data reveal, for the first time, Au(I) compounds with powerful inhibitory capacity towards SR Ca2+ATPase function. These results also show, unprecedently, that Au (III) and Au(I) compounds can act as P-type ATPase inhibitors, unveiling a potential application of these complexes.

Heterofunctional ruthenium(II) carbosilane dendrons, a new class of dendritic molecules to fight against prostate cancer

A family of heterofunctional Schiff base carbosilane metallodendrons with [Ru(η⁵-C₅H₅)(PTA)Cl] (PTA = 1,3,5-triaza-7-phosphatricyclo-[3.3.1.1]decane) at the focal point and dimethylamino groups on the periphery are described. The new systems have proved their ability to interact with biological molecules such as Human Serum Albumin (HSA) without affecting its secondary structure and erythrocytes membranes, causing haemolysis in a dose and generation dependent way. The combination of two active functional groups in one single dendritic platform has shown a cooperative effect in the viability of HeLa and PC-3 cells, with the second generation derivative standing out as the most promising with the lowest IC₅₀. Experiments focused on advanced prostate cancer have shown an antimetastasic activity for those metallodendrons, hindering the adhesion of cells in one of the main targets of metastasis, bones, and inhibiting cell migration. Finally, the second generation metallodendron with one single metal centre and four dimethylamino groups on the dendritic wedge, was selected for an ex vivo experiment in nude mice with advanced prostate cancer inhibiting the tumour growth in a 40% compared to control mice.

Mild and Efficient Synthesis of Diverse Organo-AuI -L Complexes in Green Solvents

An exceptionally mild and efficient method was developed for the preparation of (hetero)aryl-Au^I -L complexes using ethanol or water as the reaction medium at room temperature and Ar-B(triol)K boronates as the transmetalation partner. The reaction does not need an exogeneous base or other additives, and quantitative yields can be achieved through a simple filtration as the only required purification method, which obviates considerable waste associated with alternative workup methods. A broad reaction scope was demonstrated with respect to both the L and (hetero)aryl ligands on product Au complexes. Despite the polar reaction medium, large polycyclic aromatic hydrocarbon units can be incorporated on the Au complexes in very good to excellent yields. The approach was demonstrated for the chemoselective manipulation of orthogonally protected aryl boronates to afford a new class of N-heterocyclic carbene-Au-aryl complexes. A mechanistic rationale was proposed.

Novel phosphine sulphide gold(i) complexes: topoisomerase I inhibitors and antiproliferative agents

Gold(i) increases the cytotoxicity of phosphine sulfide quinolines against cancer cell lines, while heterocycles maintain the TopI inhibitory activity.

Synthesis, characterization, and biological studies of multidentate gold(i) and gold(iii) NHC complexes

The synthesis and characterization of a novel macrocyclic Au(iii) N-heterocyclic carbene (NHC) imidazolyl complex, a novel macrocyclic tetra-NHC benzimidazole ligand, and the corresponding Ag(i) and Au(i) complexes are presented. Single-crystal X-ray diffraction analysis of the Au(i) benzimidazolyl complex 3 reveals an unusual structure, differing from the respective Au(i) imidazolyl complex 4. Both complexes have a Au₄L₂ composition; however, 3 has two C-Au(i)-C units acting as a connection between the two ligands with two Au(i) atoms being linearly coordinated inside the cavity of the macrocyclic ligand. In the case of complex 4, the structure shows a box-type coordination with all four Au(i) atoms being located between the two ligands. Stability studies in cell culture medium are performed for subsequent MTT assays and they show an unprecedented proton-to-deuterium exchange of the methylene bridge of the Au(iii) imidazolyl complex. In MTT assays, the tetranuclear acyclic Au(i) complex 5 displays the lowest IC₅₀ values in MCF-7, PC3, and A2780cisR cells with a selective cytotoxicity for MCF-7 and A2780cisR cells.

Anticancer auranofin engages 3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMGCR) as a target

Auranofin (AuRF) has been reported to display anticancer activity and has entered several clinical trials; however, its mechanism of action remains largely unknown. In this work, the anticancer mechanism of auranofin was investigated using a proteomics strategy entailing subcellular fractionation prior to mass spectrometric analysis. Bioinformatics analysis of the nuclear sub-proteomes revealed that tumor suppressor p14^ARF is a key regulator of transcription. Through independent analysis, we validated that up-regulation of p14^ARF is associated with E2F-dependent transcription and increased p53 expression. Our analyses further reveal that 3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMGCR), which is the rate-determining enzyme of the mevalonate pathway, is a novel target of auranofin with half maximal inhibitory concentration at micromolar levels. The auranofin-induced cancer cell death could be partially reverted by the addition of downstream products of the mevalonate pathway (mevalonolactone or geranyleranyl pyrophosphate (GGPP)), implying that auranofin may target the mevalonate pathway to exert its anticancer effect.

Expanding the biological utility of bis-NHC gold(i) complexes through post synthetic carbamate conjugation

We report the synthesis of a novel hydroxyl-functionalised heteroleptic bis-NHC gold(i) complex that permits conjugation to various amines via carbamate bond formation. The resulting derivatives were studied in vitro using cell proliferation assays and fluorescent microscopic imaging of human cancer cell lines.

Chiral Cyclometalated Oxazoline Gold(III) Complex-Catalyzed Asymmetric Carboalkoxylation of Alkynes

Asymmetric catalysis by using novel chiral O,O'-chelated 4,4'-biphenol cyclometalated oxazoline gold(III) complexes has been developed. A high yield (≤89%) and a high enantioselectivity (≤90% ee) were achieved in asymmetric carboalkoxylation of alkynes. Enantioselectivity could be significantly improved from 19% to 90% ee by increasing the steric size of the substituent on the chiral oxazoline ligand. Catalytically active Au^III species and the origin of chiral induction are proposed.

Reactivity of Gold(I) Monocarbene Complexes with Protein Targets: A Theoretical Study

Neutral N–heterocyclic carbene gold(I) compounds such as IMeAuCl are widely used both in homogeneous catalysis and, more recently, in medicinal chemistry as promising antitumor agents. In order to shed light on their reactivity with protein side chains, we have carried out density functional theory (DFT) calculations on the thermodynamics and kinetics of their reactions with water and various nucleophiles as a model of plausible protein binding sites such as arginine, aspartic acid, asparagine, cysteine, glutamic acid, glutamine, histidine, lysine, methionine, selenocysteine, and the N-terminal group. In agreement with recent experimental data, our results suggest that IMeAuCl easily interacts with all considered biological targets before being hydrated—unless sterically prevented—and allows the establishment of an order of thermodynamic stability and of kinetic reactivity for its binding to protein residues.

Synthesis and biological evaluation of thiolate gold(i) complexes as thioredoxin reductase (TrxR) and glutathione reductase (GR) inhibitors

Au(i) complexes with PPh₂py and thiolate ligands are prepared. The complexes are shown considerable cytotoxic activities and those efficiently inhibit the TrxRs and GR.

Theoretical insight into joint photodynamic action of a gold(i) complex and a BODIPY chromophore for singlet oxygen generation

Inclusion of a heavy gold atom in a peripheral position of BODIPY is enough to promote ISC.

Anticancer properties of gold complexes with biologically relevant ligands

The present review highlights our findings in the field of antitumor gold complexes bearing biologically relevant molecules, such as DNA-bases, amino acids or peptide derivatives. The results show that very active complexes are achieved with this sort of ligands in several cancer cells. In these compounds the gold center is bonded to these biological molecules mainly through a sulfur atom belonging to a cysteine moiety or to a thionicotinic moiety as result of the functionalization of the biological compounds, and additionally phosphines or N-heterocyclic carbenes are present as ancillary ligands. These robust compounds are stable in the biological media and can be transported to their targets without previous deactivation. The presence of these scaffolds represents a good approach to obtain complexes with improved biologically activity, better transport and biodistribution to cancer cells. Thioredoxin reductase (TrxR) has been shown as the main target for these complexes and in some cases, DNA interactions has been also observed.

Gold-containing compound BDG-I inhibits the growth of A549 lung cancer cells through the deregulation of miRNA expression

Gold complex bis(diethyldithiocarbamato-gold(I)) bis(diphenylphosphino) methane (BDG-I) is cytotoxic toward different cancer cell lines. We compared the cytotoxic effect of BDG-I with that of cisplatin in the A549 lung cancer cell line. Additionally, we investigated the molecular mechanism underlying the toxic effect of BDG-I toward the A549 cell line and the identification of cancer-related miRNAs likely to be involved in killing the lung cancer cells. Further, X-ray crystallographic data of the compound were acquired. Using microarray, global miRNA expression profiling in BDG-I-treated A549 cells revealed 64 upregulated and 86 downregulated miRNAs, which targeted 4689 and 2498 genes, respectively. Biological network connectivity of the miRNAs was significantly higher for the upregulated miRNAs than for the downregulated miRNAs. Two of the 10 most upregulated miRNAs (hsa-mir-20a-5p and hsa-mir-15b-5p) were associated with lung cancer. AmiGo2 server and Panther pathway analyses indicated significant enrichment in transcription regulation of miRNA target genes that promote intrinsic kinase-mediated signaling, TGF-β, and GnRH signaling pathways, as well as oxidative stress responses. BDG-I crystal structure X-ray diffraction studies revealed gold–gold intramolecular interaction [Au…Au = 3.1198 (3) Å] for a single independent molecule, reported to be responsible for its activity against cancer. Our present study sheds light on the development of novel gold complex with favorable anti-cancer therapeutic functionality.

Critical assessment of different methods for quantitative measurement of metallodrug-protein associations

Quantitative screening for potential drug-protein binding is an essential step in developing novel metal-based anticancer drugs. ICP-MS approaches are at the core of this task; however, many applications lack in the capability of large-scale high-throughput screenings and proper validation. In this work, we critically discuss the analytical figures of merit and the potential method-based quantitative differences applying four different ICP-MS strategies to ex vivo drug-serum incubations. Two candidate drugs, more specifically, two Pt(IV) complexes with known differences of binding affinity towards serum proteins were selected. The study integrated centrifugal ultrafiltration followed by flow injection analysis, turbulent flow chromatography (TFC), and size exclusion chromatography (SEC), all combined with inductively coupled plasma-mass spectrometry (ICP-MS). As a novelty, for the first time, UHPLC SEC-ICP-MS was implemented to enable rapid protein separation to be performed within a few minutes at > 90% column recovery for protein adducts and small molecules. Graphical abstract Quantitative screening for potential drug-protein binding is an essential step in developingnovel metal-based anticancer drugs.

The Next Generation of Anticancer Metallopharmaceuticals: Cancer Stem Cell-Active Inorganics

Cancer stem cells (CSCs) are heavily linked to fatal incidences of cancer relapse and metastasis. Conventional cancer therapies such as surgery, chemotherapy and radiation are largely futile against CSCs. Therefore, highly original approaches are needed to overcome CSCs and to provide durable, long-term clinical outcomes. Many academia- and pharmaceutical-led studies aimed at developing chemical or biological anti-CSC agents are ongoing; however, the application of inorganic compounds is rare. In this minireview, we discuss how the chemical diversity and versatility offered by metals has been harnessed to develop an unprecedented, emerging class of metallopharmaceuticals: CSC-active inorganics. A detailed account of their mechanism(s) of action is provided, and possible future directions for exploration are also put forward.

A clickable NHC-Au(i)-complex for the preparation of stimulus-responsive metallopeptide amphiphiles

We report the synthesis of an alkyne functionalised NHC-Au(i)-complex which is conjugated with amphiphilic oligopeptides using a copper(i) catalysed cycloaddition. The resulting Au(i)-metalloamphiphiles are shown to self-assemble into charge-regulated stimulus-responsive supramolecular polymers in water via a weakly cooperative polymerisation mechanism.

Pharmacomodulation on Gold-NHC complexes for anticancer applications - is lipophilicity the key point?

A series of four new mononuclear cationic gold(I) complexes containing nitrogen functionalized N-heterocyclic carbenes (NHCs) was synthesized and fully characterized by spectroscopic methods. The X-ray structures of three complexes are presented. These lipophilic gold(I) complexes originate from a pharmacomodulation of previously described gold(I)-NHC complexes, by replacing an aliphatic spacer with an aromatic one. The Log P values of the resulting complexes increased by 0.7-1.5, depending on the substituents in comparison to the aliphatic-linker systems. The new series of complexes has been investigated in vitro for their anti-cancer activities in PC-3 (prostate cancer) and T24 (bladder cancer) cell lines and in the non-cancerous MC3T3 (osteoblast) cell line. All tested complexes show high activities against the cancer cell lines with GI₅₀ values lower than 500 nM. One complex (11) has been selected for further investigations. It has been tested in vitro in six cancer cell lines from different origins (prostate, bladder, lung, bone, liver and breast) and two non-cancerous cell lines (osteoblasts, fibroblasts). Moreover, cellular uptake measurements were indicative of a good bioavailability. By various biochemical assays, this complex was found to effectively inhibit the thioredoxin reductase (TrxR) and its cytotoxicity towards prostate PC-3, bladder T24 and liver HepG2 cells was found to be ROS-dependent.