Half-sandwich Os(ii) and Ru(ii) bathophenanthroline complexes: anticancer drug candidates with unusual potency and a cellular activity profile in highly invasive triple-negative breast cancer cells

Multifunctional nanocomposites utilizing ruthenium (II) complex/manganese (IV) dioxide nanoparticle for synergistic reinforcing radioimmunotherapy

Radiotherapy (RT) stands as a frontline treatment modality in clinical breast oncology, yet challenges like ROS reduction, high toxicity, non-selectivity, and hypoxia hinder efficacy. Additionally, RT administered at different doses can induce varying degrees of radioimmunotherapy. High doses of radiation (>10 Gy) may result in immune suppression, while moderate doses (4-10 Gy), although capable of mitigating the immune suppression caused by high-dose radiation, are often insufficient in effectively killing tumor cells. Therefore, enhancing the generation of ROS and ameliorating the tumor hypoxic immune-suppressive microenvironment at moderate radiation doses could potentially drive radiation-induced immune responses, offering a fundamental solution to the limitations of RT. In this study, a novel multifunctional nanoplatform, RMLF, integrating a Ru (II) complex into folate-functionalized liposomes with BSA-MnO2 nanoparticles was proposed. Orthogonal experimental optimization enhances radiosensitization via increasing accumulation in cancer cells, elevating ROS, and contributing to a dual enhancement of the cGAS-STING-dependent type I IFN signaling pathway, aimed to overcome the insufficient DAMPs typically seen in the conventional RT at 4 Gy. Such a strategy effectively activated cytotoxic T lymphocytes for infiltration into tumor tissues and promoted the polarization of tumor-associated macrophages from the M2 to M1 phenotype, substantially bolstering immune memory responses. This pioneering approach represents the first use of a ruthenium complex in radioimmunotherapy, activating the cGAS-STING pathway to amplify immune responses, overcome RT resistance, and extend immunotherapeutic potential.

Recent trends in the design and delivery strategies of ruthenium complexes for breast cancer therapy

As the most frequent and deadly type of cancer in women, breast cancer has a high propensity to spread to the brain, bones, lymph nodes, and lungs. The discovery of cisplatin marked the beginning of the development of anticancer metal-based medications, although the drug's severe side effects have limited its usage in clinical settings. The remarkable antimetastatic and anticancer activity of different ruthenium complexes such as NAMI-A, KP1019, KP1339, etc. reported in the 1980s has bolstered the discovery of ruthenium complexes with various types of ligands for anticancer applications. The review meticulously elucidates the cytotoxic and antimetastatic potential of reported ruthenium complexes against breast cancer cells. Notably, arene-based and cyclometalated ruthenium complexes emerge as standout candidates, showcasing remarkable potency with notably low IC50 values. These findings underscore the promising therapeutic avenues offered by ruthenium-based compounds, particularly in addressing the challenges posed by conventional treatments in refractory or aggressive breast cancer subtypes. Moreover, the review comprehensively integrates a spectrum of ruthenium complexes, spanning traditional metal complexes to nano-based formulations and light-activated variants, underscoring the versatility and adaptability of ruthenium chemistry in breast cancer therapy.

A Cyclometalated Ruthenium(II) Complex Induces Oncosis for Synergistic Activation of Innate and Adaptive Immunity

An optimal cancer chemotherapy regimen should effectively address the drug resistance of tumors while eliciting antitumor-immune responses. Research has shown that non-apoptotic cell death, such as pyroptosis and ferroptosis, can enhance the immune response. Despite this, there has been limited investigation and reporting on the mechanisms of oncosis and its correlation with immune response. Herein, we designed and synthesized a Ru(II) complex that targeted the nucleus and mitochondria to induce cell oncosis. Briefly, the Ru(II) complex disrupts the nucleus and mitochondria DNA, which active polyADP-ribose polymerase 1, accompanied by ATP consumption and porimin activation. Concurrently, mitochondrial damage and endoplasmic reticulum stress result in the release of Ca2+ ions and increased expression of Calpain 1. Subsequently, specific pore proteins porimin and Calpain 1 promote cristae destruction or vacuolation, ultimately leading to cell membrane rupture. The analysis of RNA sequencing demonstrates that the Ru(II) complex can initiate the oncosis-associated pathway and activate both innate and adaptive immunity. In vivo experiments have confirmed that oncosis promotes dendritic cell maturation and awakens adaptive cytotoxic T lymphocytes but also activates the innate immune by inducing the polarization of macrophages towards an M1 phenotype.

Effects induced by η6-p-cymene ruthenium(II) complexes on Langmuir monolayers mimicking cancer and healthy cell membranes do not correlate with their toxicity

The mechanism of chemotherapeutic action of Ru-based drugs involves plasma membrane disruption and valuable insights into this process may be gained using cell membrane models. The interactions of a series of cytotoxic η6-p-cymene ruthenium(II) complexes, [Ru(η6-p-cymene)P(3,5-C(CH3)3-C6H3)3Cl2] (1), [Ru(η6-p-cymene)P(3,5-CH3-C6H3)3Cl2] (2), [Ru(η6-p-cymene)P(4-CH3O-3,5-CH3-C6H2)3Cl2] (3), and [Ru(η6-p-cymene)P(4-CH3O-C6H4)3Cl2] (4), were examined using Langmuir monolayers as simplified healthy and cancerous outer leaflet plasma membrane models. The cancerous membrane (CM1 and CM2) models contained either 40 % 1,2- dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) or 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC), 30 % cholesterol (Chol), 20 % 1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine (DPPE), and 10 % 1,2-dipalmitoyl-sn-glycero-3-phospho-l-serine (DPPS). Meanwhile, the healthy membrane (HM1 and HM2) models were composed of 60 % DPPC or DOPC, 30 % Chol and 10 % DPPE. The complexes affected surface pressure isotherms and decreased compressional moduli of cancerous and healthy membrane models, interacting with the monolayers headgroup and tails according to data from polarization-modulated infrared reflection absorption spectroscopy (PM-IRRAS). However, the effects did not correlate with the toxicity of the complexes to cancerous and healthy cells. Multidimensional projection technique showed that the complex (1) induced significant changes in the CM1 and HM1 monolayers, though it had the lowest cytotoxicity against cancer cells and is not toxic to healthy cells. Moreover, the most toxic complexes (2) and (4) were those that least affected CM2 and HM2 monolayers. The findings here support that the ruthenium complexes interact with lipids and cholesterol in cell membrane models, and their cytotoxic activities involve a multifaceted mode of action beyond membrane disruption.

Lysosome-targeted ruthenium(II) complex encapsulated with pluronic® F-127 induces oncosis in A549 cells

Transition metal complexes with characteristics of unique packaging in nanoparticles and remarkable cancer cell cytotoxicity have emerged as potential alternatives to platinum-based antitumor drugs. Here we report the synthesis, characterization, and antitumor activities of three new Ruthenium complexes that introduce 5-fluorouracil-derived ligands. Notably, encapsulation of one such metal complex, Ru3, within pluronic® F-127 micelles (Ru3-M) significantly enhanced Ru3 cytotoxicity toward A549 cells by a factor of four. To determine the mechanisms underlying Ru3-M cytotoxicity, additional in vitro experiments were conducted that revealed A549 cell treatment with lysosome-targeting Ru3-M triggered oxidative stress, induced mitochondrial membrane potential depolarization, and drastically reduced intracellular ATP levels. Taken together, these results demonstrated that Ru3-M killed cells mainly via a non-apoptotic pathway known as oncosis, as evidenced by observed Ru3-M-induced cellular morphological changes including cytosolic flushing, cell swelling, and cytoplasmic vacuolation. In turn, these changes together caused cytoskeletal collapse and activation of porimin and calpain1 proteins with known oncotic functions that distinguished this oncotic process from other cell death processes. In summary, Ru3-M is a potential anticancer agent that kills A549 cells via a novel mechanism involving Ru(II) complex triggering of cell death via oncosis.

Neuroprotective Effects and Therapeutic Potential of Dichloroacetate: Targeting Metabolic Disorders in Nervous System Diseases

Dichloroacetate (DCA) is an investigational drug used to treat lactic acidosis and malignant tumours. It works by inhibiting pyruvate dehydrogenase kinase and increasing the rate of glucose oxidation. Some studies have documented the neuroprotective benefits of DCA. By reviewing these studies, this paper shows that DCA has multiple pharmacological activities, including regulating metabolism, ameliorating oxidative stress, attenuating neuroinflammation, inhibiting apoptosis, decreasing autophagy, protecting the blood‒brain barrier, improving the function of endothelial progenitor cells, improving mitochondrial dynamics, and decreasing amyloid β-protein. In addition, DCA inhibits the enzyme that metabolizes it, which leads to peripheral neurotoxicity due to drug accumulation that may be solved by individualized drug delivery and nanovesicle delivery. In summary, in this review, we analyse the mechanisms of neuroprotection by DCA in different diseases and discuss the causes of and solutions to its adverse effects.

A Family of Cagelike Mn-Silsesquioxane/Bathophenanthroline Complexes: Synthesis, Structure, and Catalytic and Antifungal Activity

This study reports a novel family of cage manganesesilsesquioxanes prepared via complexation with bathophenanthroline (4,7-diphenyl-1,10-phenanthroline). The resulting Mn4-, Mn6Li2-, and Mn4Na-compounds exhibit several unprecedented cage metallasilsesquioxane structural features, including intriguing self-assembly of silsesquioxane ligands. Complexes were tested in vitro for fungicidal activity against seven classes of phytopathogenic fungi. The representative Mn4Na-complex acts as a catalyst in the cycloaddition of CO2 to epoxides under solvent-free conditions to form cyclic carbonates in good yields.

Chemistry towards Biology-Instruct: Snapshot

The knowledge of interactions between different molecules is undoubtedly the driving force of all contemporary biomedical and biological sciences. Chemical biology/biological chemistry has become an important multidisciplinary bridge connecting the perspectives of chemistry and biology to the study of small molecules/peptidomimetics and their interactions in biological systems. Advances in structural biology research, in particular linking atomic structure to molecular properties and cellular context, are essential for the sophisticated design of new medicines that exhibit a high degree of druggability and very importantly, druglikeness. The authors of this contribution are outstanding scientists in the field who provided a brief overview of their work, which is arranged from in silico investigation through the characterization of interactions of compounds with biomolecules to bioactive materials.

Stability of a half-sandwich Os(II) complex with indomethacin-functionalized ligand in the presence of carboxypeptidase A

In the presence of carboxypeptidase, the hydrolytically stable complex [Os(η⁶-pcym)(L2)Cl]PF₆ (2) partially released the bioactive substituent indomethacin, bound through the amide bond to the chelating 2-(1,3,4-thiadiazol-2-yl)pyridine-based moiety of L2. Stability in the presence of other relevant biomolecules (GSH, NADH, GMP) and cancer cell viability were also studied.

Structural and morphological changes of breast cancer cells induced by iron(II) complexes

Metal-based complexes are well-established cancer chemotherapeutic drug candidates. Although our knowledge regarding their exact activity vs. toxicity profile is incomplete, changes in cell membrane biophysical properties and cytoskeletal structures have been implicated as part of the mechanism of action. Thus, in this work, we characterised the effects of iron(II)-based complexes on the structural and morphological properties of epithelial non-tumorigenic (MCF 10A) and tumorigenic (MDA-MB-231) breast cell lines using atomic force microscopy (AFM), flow cytometry and immunofluorescence microscopy. At 24 h of exposure, both the MCF 10A and MDA-MB-231 cells experienced a cell softening, and an increase in size followed by a re-stiffening at 96 h. In addition, the triple negative breast cancer cell line, MDA-MB-231, sustained a notable cytoskeletal and mitochondrial reorganization with increased actin stress fibers and cell-to-cell communication structures. An extensive all-atom molecular dynamic simulation suggests a possible direct and unassisted internalization of the metallodrug candidate, and confirmed that the cellular effects could not be ascribed to the simple physical interaction of the iron-based complexes with the biological membrane. These observations provide an insight into a link between the mechanisms of action of such iron-based complexes as anti-cancer treatment and cytoskeletal architecture.

Synthesis, Structure and Cytotoxicity of N,N and N,O-Coordinated RuII Complexes of 3-Aminobenzoate Schiff Bases against Triple-negative Breast Cancer

Half-sandwich Ru^II complexes, [(YZ)Ru^II (η⁶ -arene)(X)]+, (YZ=chelating bidentate ligand, X=halide), with N,N and N,O coordination (1-9) show significant antiproliferative activity against the metastatic triple-negative breast carcinoma (MDA-MB-231). 3-aminobenzoic acid or its methyl ester is used in all the ligands while varying the aldehyde for N,N and N,O coordination. In the N,N coordinated complex the coordinated halide(X) is varied for enhancing stability in solution (X=Cl, I). Rapid aquation and halide exchange of the pyridine analogues, 2 and 3, in solution are a major bane towards their antiproliferative activity. Presence of free -COOH group (1 and 4) make complexes hydrophilic and reduces toxicity. The imidazolyl 3-aminobenzoate based N,N coordinated 5 and 6 display better solution stability and efficient antiproliferative activity (IC₅₀ ca. 2.3-2.5 μM) compared to the pyridine based 2 and 3 (IC₅₀ >100 μM) or the N,O coordinated complexes (7-9) (IC₅₀ ca. 7-10 μM). The iodido coordinated, 6, is resistant towards aquation and halide exchange. The N,O coordinated 7-9 underwent instantaneous aquation at pH 7.4 generating monoaquated complexes stable for at least 6 h. Complexes 5 and 6, bind to 9-ethylguanine (9-EtG) showing propensity to interact with DNA bases. The complexes may kill via apoptosis as displayed from the study of 8. The change in coordination mode and the aldehyde affected the solution stability, antiproliferative activity and mechanistic pathways. The N,N coordinated (5 and 6) exhibit arrest in the G2/M phase while the N,O coordinated 8 showed arrest in the G0/G1 phase.

Metal complexes against breast cancer stem cells

With the highest incidence, breast cancer is the leading cause of cancer deaths among women in the world. Tumor metastasis is the major contributor of high mortality in breast cancer, and the existence of cancer stem cells (CSCs) has been proven to be the cause of tumor metastasis. CSCs are a small proportion of tumor cells, and they are associated with self-renewal and tumorigenic potential. Given the significance of CSCs in tumor initiation, expansion, relapse, resistance, and metastasis, studies should investigate and discover effective anticancer agents that can not only inhibit the proliferation of differentiated tumor cells but also reduce the tumorigenic capability of CSCs. Thus, new therapies must be discovered to treat and prevent this severely hazardous disease of human beings. The success of platinum complexes in cancer treatment has laid the basic foundation for the utilization of metal complexes in the treatment of malignant cancers, in particular the highly aggressive triple-negative breast cancer. Importantly, metal complexes currently have diverse and versatile competences in the therapeutic targeting of CSCs. The anti-CSC properties provide a strong impetus for the development of novel metal-based compounds for the targeting of CSCs and treatment of chemotherapy-resistant and relapsed tumors. In this review, we provide the latest advances in metal complexes including platinum, ruthenium, osmium, iridium, manganese, cobalt, nickel, copper, zinc, palladium, and tin complexes against breast CSCs obtained over the past decade, with pertinent literature including those published until 2021.

Covalent and noncovalent interactions of coordination compounds with DNA: An overview

Deoxyribonucleic acid plays a central role in crucial cellular processes, and many drugs exert their effects through binding to DNA. Since the discovery of cisplatin and its derivatives considerable attention of researchers has been focused on the development of novel anticancer metal-based drugs. Transition metal complexes, due to their great diversity in size and structure, have a big potential to modify DNA through diverse types of interactions, making them the prominent class of compounds for DNA targeted therapy. In this review we describe various binding modes of metal complexes to duplex DNA based on covalent and noncovalent interactions or combination of both. Specific examples of each binding mode as well as possible cytotoxic effects of metal complexes in tumor cells are presented.

Evaluation of the In Vitro and In Vivo Efficacy of Ruthenium Polypyridyl Compounds against Breast Cancer

The clinical success of cisplatin, carboplatin, and oxaliplatin has sparked the interest of medicinal inorganic chemistry to synthesize and study compounds with non-platinum metal centers. Despite Ru(II)-polypyridyl complexes being widely studied and well established for their antitumor properties, there are not enough in vivo studies to establish the potentiality of this type of compound. Therefore, we report to the best of our knowledge the first in vivo study of Ru(II)-polypyridyl complexes against breast cancer with promising results. In order to conduct our study, we used MCF7 zebrafish xenografts and ruthenium complexes [Ru(bipy)₂(C₁₂H₈N₆-N,N)][CF₃SO₃]₂Ru1 and [{Ru(bipy)₂}₂(μ-C₁₂H₈N₆-N,N)][CF₃SO₃]₄Ru2, which were recently developed by our group. Ru1 and Ru2 reduced the tumor size by an average of 30% without causing significant signs of lethality when administered at low doses of 1.25 mg·L^-1. Moreover, the in vitro selectivity results were confirmed in vivo against MCF7 breast cancer cells. Surprisingly, this work suggests that both the mono- and the dinuclear Ru(II)-polypyridyl compounds have in vivo potential against breast cancer, since there were no significant differences between both treatments, highlighting Ru1 and Ru2 as promising chemotherapy agents in breast cancer therapy.

Metal- and metalloid-based compounds to target and reverse cancer multidrug resistance

Drug resistance remains the major cause of cancer treatment failure especially at the late stage of the disease. However, based on their versatile chemistry, metal and metalloid compounds offer the possibility to design fine-tuned drugs to circumvent and even specifically target drug-resistant cancer cells. Based on the paramount importance of platinum drugs in the clinics, two main areas of drug resistance reversal strategies exist: overcoming resistance to platinum drugs as well as multidrug resistance based on ABC efflux pumps. The current review provides an overview of both aspects of drug design and discusses the open questions in the field. The areas of drug resistance covered in this article involve: 1) Altered expression of proteins involved in metal uptake, efflux or intracellular distribution, 2) Enhanced drug efflux via ABC transporters, 3) Altered metabolism in drug-resistant cancer cells, 4) Altered thiol or redox homeostasis, 5) Altered DNA damage recognition and enhanced DNA damage repair, 6) Impaired induction of apoptosis and 7) Altered interaction with the immune system. This review represents the first collection of metal (including platinum, ruthenium, iridium, gold, and copper) and metalloid drugs (e.g. arsenic and selenium) which demonstrated drug resistance reversal activity. A special focus is on compounds characterized by collateral sensitivity of ABC transporter-overexpressing cancer cells. Through this approach, we wish to draw the attention to open research questions in the field. Future investigations are warranted to obtain more insights into the mechanisms of action of the most potent compounds which target specific modalities of drug resistance.

Unexpected solution behaviour of ester-functionalized half-sandwich Ru(II) and Ir(III) complexes

Complexes [Ru(η6-pcym)(bpydca)Cl]PF6 (Rudca) and [Ir(η5-Cp*)(bpydca)Cl]PF6 (Irdca) were developed as model compounds for the investigation of multi-targeted ester-functionalized half-sandwich ruthenium(ii) and iridium(iii) complexes; pcym = 1-methyl-4-(propan-2-yl)benzene (p-cymene), bpydca = 2,2'-bipyridine-4,4'-diyldimethanediyl bis(dichloroacetate), Cp* = pentamethylcyclopentadienyl. Aiming to understand the in-solution behaviour of these first-in-class complexes containing the pyruvate dehydrogenase kinase inhibitor dichloroacetate (dca) as the terminal bioactive substituent, several experiments were performed under aqueous conditions for Rudca and Irdca, as well as for compounds [Ru(η6-pcym)(bpyOH)Cl]PF6 (RuOH) and [Ir(η5-Cp*)(bpyOH)Cl]PF6 (IrOH), and acetyl analogues [Ru(η6-pcym)(bpyac)Cl]PF6 (Ruac) and [Ir(η5-Cp*)(bpyac)Cl]PF6 (Irac) bearing a different (biologically inactive) terminal substituent; bpyOH = 2,2'-bipyridine-4,4'-diyldimethanol, bpyac = 2,2'-bipyridine-4,4'-diyldimethanediyl diacetate. The experiments were also conducted in the presence of porcine liver esterase (PLE). All the six complexes were characterized by relevant techniques (e.g., NMR and mass spectrometry), including a single-crystal X-ray analysis of complexes Rudca, Ruac, RuOH and IrOH. Although designed as model compounds, Rudca, Irdca, RuOH and IrOH were also screened for their antiproliferative activity in four human cancer cell lines (HCT116 colon carcinoma, MDA-MB-231 and MCF-7 breast adenocarcinomas, DU145 prostate carcinoma), where the tested complexes did not show any effect (IC50 > 100 μM).

Exploring the Potential of Metallodrugs as Chemotherapeutics for Triple Negative Breast Cancer

This review focuses on studies of coordination and organometallic compounds as potential chemotherapeutics against triple negative breast cancer (TNBC) which has one of the poorest prognoses and worst survival rates from all breast cancer types. At present, chemotherapy is still the standard of care for TNBC since only one type of targeted therapy has been recently developed. References for metal-based compounds studied in TNBC cell lines will be listed, and those of metal-specific reviews, but a detailed overview will also be provided on compounds studied in vivo (mostly in mice models) and those compounds for which some preliminary mechanistic data was obtained (in TNBC cell lines and tumors) and/or for which bioactive ligands have been used. The main goal of this review is to highlight the most promising metal-based compounds with potential as chemotherapeutic agents in TNBC.

Cis,cis,trans-[PtIVCl2(NH3)2(perillato)2], a dual-action prodrug with excellent cytotoxic and antimetastatic activity

Two Pt(iv) conjugates containing one or two molecules of perillic acid (4-isopropenylcyclohexene-1-carboxylic acid), an active metabolite of limonene, were synthesized both with traditional and microwave-assisted methods and characterized. Their antiproliferative activity was tested on a panel of human tumor cell lines. In particular, cis,cis,trans-[Pt^IVCl₂(NH₃)₂(perillato)₂] exhibited excellent antiproliferative and antimetastatic activity on A-549 lung tumor cells at nanomolar concentrations. A number of in vitro biological tests were performed to decipher some aspects of its mechanism of action, including transwell migration and invasion as well as wound healing assay.

Elemental mapping of half-sandwich azopyridine osmium arene complexes in cancer cells

Nanofocused synchrotron X-ray fluorescence and inductively coupled plasma-mass spectrometry provide insights into time-dependent ligand exchange reactions of organo-osmium anticancer complexes in cancer cells. Created with Biorender.com.

A cytotoxic nitrido-osmium(VI) complex induces caspase-mediated apoptosis in HepG2 cancer cells

The osmium(vi) nitrido complex [OsVI(N)(sap)(py)Cl] is a potential anti-cancer drug with promising in vitro antiproliferative activities toward a panel of cancer cell lines, including cisplatin-resistant cells (IC50 values of 2.8-13.8 μM). This drug targets DNA and changes its conformation via covalent binding and insertion. In vitro studies indicate that the drug induces HepG2 cells G2/M phase arrest, disrupts the mitochondrial membrane potential and causes caspase-mediated apoptosis. Further in vivo studies using HepG2-bearing nude mice reveal that this drug not only shows good antitumor efficacy of inhibiting tumor growth, but also does not show the side effect of weight loss.

Ruthenium(II)-Arene Thiocarboxylates: Identification of a Stable Dimer Selectively Cytotoxic to Invasive Breast Cancer Cells

Ru^II -arene complexes provide a versatile scaffold for novel anticancer drugs. Seven new Ru^II -arene-thiocarboxylato dimers were synthesized and characterized. Three of the complexes (2 a, b and 5) showed promising antiproliferative activities in MDA-MB-231 (human invasive breast cancer) cells, and were further tested in a panel of fifteen cancerous and noncancerous cell lines. Complex 5 showed moderate but remarkably selective activity in MDA-MB-231 cells (IC₅₀ =39±4 μm Ru). Real-time proliferation studies showed that 5 induced apoptosis in MDA-MB-231 cells but had no effect in A549 (human lung cancer, epithelial) cells. By contrast, 2 a and b showed moderate antiproliferative activity, but no apoptosis, in either cell line. Selective cytotoxicity of 5 in aggressive, mesenchymal-like MDA-MB-231 cells over many common epithelial cancer cell lines (including noninvasive breast cancer MCF-7) makes it an attractive lead compound for the development of specifically antimetastatic Ru complexes with low systemic toxicity.

AqF026 may act as a cancer therapeutic agent via inducing cancer cell oncosis

Cancer is one of the leading causes of death worldwide, and metastasis is the major cause of death in cancer, therefore, treatments to attenuate metastasis are urgently needed. Cell migration is indispensable in metastatic cascade, and aquaporins (AQPs) promote cell migration by facilitating water influx at cell front (lamellipodia). In fact, AQPs overexpressed widely among many cancer types. Accordingly, previous efforts of targeting AQPs as strategies of cancer treatments were based on AQP inhibitors, yet the efficacy of AQP inhibition was limited based on recent surveys. On the contrary, whether AQP agonist has role in cancer treatments has not been explored. AqF026, an AQP1 agonist, was initially applied to a mouse model of peritoneal dialysis. Herein, we aimed to apply AqF026 to magnify the water influx into lamellipodia of migrating cancer cells so as to induce oncosis by causing overloaded cancer cell swelling in advance of metastatic cascade. Cell swelling is a characteristic of oncosis. With impairment or insufficient regulatory volume decrease (RVD), cell swelling can lead to oncosis. Cancer cells with metastatic potentials shared the same population of cancer cells with multidrug resistance (MDR) lineage, and the impairment or insufficient RVD is shown in cancer cells with MDR. Taken together, the author hypothesized that given appropriate concentration or dose of AQP1 agonist AqF026, the AqF026 may induce oncosis of cancer cells preferentially rather than normal cells by causing overloaded water influx via AQP1 and consequent irreversible cell swelling.

Rationally Designed Ruthenium Complexes for Breast Cancer Therapy

Since the discovery of the anticancer potential of ruthenium-based complexes, several species were reported as promising candidates for the treatment of breast cancer, which accounts for the greatest number of new cases in women every year worldwide. Among these ruthenium complexes, species containing bioactive ligand(s) have attracted increasing attention due to their potential multitargeting properties, leading to anticancer drug candidates with a broader range of cellular targets/modes of action. This review of the literature aims at providing an overview of the rationally designed ruthenium-based complexes that have been reported to date for which ligands were carefully selected for the treatment of hormone receptor positive breast cancers (estrogen receptor (ER+) or progesterone receptor (PR+)). In addition, this brief survey highlights some of the most successful examples of ruthenium complexes reported for the treatment of triple negative breast cancer (TNBC), a highly aggressive type of cancer, regardless of if their ligands are known to have the ability to achieve a specific biological function.

Dichloroacetate (DCA) and Cancer: An Overview towards Clinical Applications

An extensive body of literature describes anticancer property of dichloroacetate (DCA), but its effective clinical administration in cancer therapy is still limited to clinical trials. The occurrence of side effects such as neurotoxicity as well as the suspicion of DCA carcinogenicity still restricts the clinical use of DCA. However, in the last years, the number of reports supporting DCA employment against cancer increased also because of the great interest in targeting metabolism of tumour cells. Dissecting DCA mechanism of action helped to understand the bases of its selective efficacy against cancer cells. A successful coadministration of DCA with conventional chemotherapy, radiotherapy, other drugs, or natural compounds has been tested in several cancer models. New drug delivery systems and multiaction compounds containing DCA and other drugs seem to ameliorate bioavailability and appear more efficient thanks to a synergistic action of multiple agents. The spread of reports supporting the efficiency of DCA in cancer therapy has prompted additional studies that let to find other potential molecular targets of DCA. Interestingly, DCA could significantly affect cancer stem cell fraction and contribute to cancer eradication. Collectively, these findings provide a strong rationale towards novel clinical translational studies of DCA in cancer therapy.

Discovery of selective, antimetastatic and anti-cancer stem cell metallohelices via post-assembly modification

Helicates and related metallofoldamers, synthesised by dynamic self-assembly, represent an area of chemical space inaccessible by traditional organic synthesis, and yet with potential for discovery of new classes of drug. Here we report that water-soluble, optically pure Fe(ii)- and even Zn(ii)-based triplex metallohelices are an excellent platform for post-assembly click reactions. By these means, the in vitro anticancer activity and most importantly the selectivity of a triplex metallohelix Fe(ii) system are dramatically improved. For one compound, a remarkable array of mechanistic and pharmacological behaviours is discovered: inhibition of Na+/K+ ATPase with potency comparable to the drug ouabain, antimetastatic properties (including inhibition of cell migration, re-adhesion and invasion), cancer stem cell targeting, and finally colonosphere inhibition competitive with the drug salinomycin.

An anticancer Os(II) bathophenanthroline complex as a human breast cancer stem cell-selective, mammosphere potent agent that kills cells by necroptosis

Conventional chemotherapy is mostly effective in the treatment of rapidly-dividing differentiated tumor cells but has limited application toward eliminating cancer stem cell (CSC) population. The presence of a very small number of CSCs may contribute to the development of therapeutic resistance, metastases, and relapse. Thus, treatment failure by developing novel anticancer drugs capable of effective targeting of CSCs is at present a major challenge for research focused on chemotherapy of cancer. Here, we show that Os(II) complex 2 [Os(η⁶-pcym)(bphen)(dca)]PF₆ (pcym = p-cymene, bphen = bathophenanthroline, and dca = dichloroacetate), is capable of efficient and selective killing CSCs in heterogeneous populations of human breast cancer cells MCF-7 and SKBR-3. Notably, its remarkable submicromolar potency to kill CSCs is considerably higher than that of its Ru analog, [Ru(η⁶-pcym)(bphen)(dca)]PF₆ (complex 1) and salinomycin, one of the most selective CSC-targeting compounds hitherto identified. Furthermore, Os(II) complex 2 reduces the formation, size, and viability of three-dimensional mammospheres which more closely reflect the tumor microenvironment than cells in traditional two-dimensional cultures. The antiproliferation studies and propidium iodide staining using flow cytometry suggest that Os(II) complex 2 induces human breast cancer stem cell death predominantly by necroptosis, a programmed form of necrosis. The results of this study demonstrate the promise of Os(II) complex 2 in treating human breast tumors. They also represent the foundation for further preclinical and clinical studies and applications of Os(II) complex 2 to comply with the emergent need for human breast CSCs-specific chemotherapeutics capable to treat chemotherapy-resistant and relapsed human breast tumors.

Luminescent ruthenium(II) polypyridyl complexes acted as radiosensitizer for pancreatic cancer by enhancing radiation-induced DNA damage

Background: Pancreatic cancer is a highly lethal malignancy which ranks 4th most common cause of cancer death in US and 6th in China. Novel drugs are required to improve the survival and prognosis of patients. Methods: Ruthenium(II) complexes with variation number of DIP ligand were synthesized and further adopted as radiosensitizer for pancreatic cancer. The influence of ruthenium(II) complexes on cell behaviors and tumor growth were investigated. The DNA binding affinity of ruthenium(II) complexes and plasmid was measured by using agarose gel electrophoresis. Results: Luminescent ruthenium(II) complex can rapidly enter into cell nuclei and consequently combine with DNA, resulting in the enhanced DNA damage induced by X-ray irradiation. Upon intratumoral injection of ruthenium(II) complex, excellent tumor growth inhibition was accomplished under ionizing radiation of human pancreatic cancer xenograft nude mice. Conclusions: Taken together, our study suggest that the ruthenium(II) polypyridyl complexes can effectively enhance radiation-induced DNA damage, which is likely to benefit the imaging-guided cancer radio-chemotherapy.