Discovery of Ruthenium(II) Metallocompound and Olaparib Synergy for Cancer Combination Therapy.

Synergistic drug combinations can extend the use of poly(ADP-ribose) polymerase inhibitors (PARPi) such as Olaparib to BRCA-proficient tumors and overcome acquired or de novo drug resistance. To identify new synergistic combinations for PARPi, we screened a "micro-library" comprising a mix of commercially available drugs and DNA-binding ruthenium(II) polypyridyl complexes (RPCs) for Olaparib synergy in BRCA-proficient triple-negative breast cancer cells. This identified three hits: the natural product Curcumin and two ruthenium(II)-rhenium(I) polypyridyl metallomacrocycles. All combinations identified were effective in BRCA-proficient breast cancer cells, including an Olaparib-resistant cell line, and spheroid models. Mechanistic studies indicated that synergy was achieved via DNA-damage enhancement and resultant apoptosis. Combinations showed low cytotoxicity toward non-malignant breast epithelial cells and low acute and developmental toxicity in zebrafish embryos. This work identifies RPC metallomacrocycles as a novel class of agents for cancer combination therapy and provides a proof of concept for the inclusion of metallocompounds within drug synergy screens.

A Photoactivated Sorafenib-Ruthenium(II) Prodrug for Resistant Hepatocellular Carcinoma Therapy through Ferroptosis and Purine Metabolism Disruption.

The curative effect of sorafenib in hepatocellular carcinoma (HCC) is limited and sorafenib resistance remains a major obstacle for HCC. To overcome this obstacle, a new photoactive sorafenib-Ru(II) complex Ru-Sora has been designed. Upon irradiation (λ = 465 nm), Ru-Sora rapidly releases sorafenib and generates reactive oxygen species, which can oxidize intracellular substances such as GSH. Cellular experiments show that irradiated Ru-Sora is highly cytotoxic toward Hep-G2 cells, including sorafenib-resistant Hep-G2-SR cells. Compared to sorafenib, Ru-Sora has a significant photoactivated chemotherapeutic effect against Hep-G2-SR cancer cells and 3D Hep-G2 multicellular tumor spheroids. Furthermore, Ru-Sora inducing apoptosis and ferroptosis is proved by GSH depletion, GPX4 downregulation, and lipid peroxide accumulation. Metabolomics results suggest that Ru-Sora exerts photocytotoxicity by disrupting the purine metabolism, which is expected to inhibit tumor development. This study provides a promising strategy for enhancing chemotherapy and combating drug-resistant HCC disease.

Note of Caution for the Aqueous Behaviour of Metal-Based Drug Candidates.

Poor aqueous solubility is one of the recurrent drawbacks of many compounds in medicinal chemistry. To overcome this limitation, the dilution of drug candidates from stock solutions of an organic solvent is common practice. However, the precise characterisation of these compounds in aqueous solutions is often neglected, leading to some uncertainties regarding the nature of the actual active species. In this communication, we demonstrate that two ruthenium complexes previously reported by our group for their chemotherapeutic potential against cancer, namely [Ru(DIP)2 (sq)](PF6 ) and [Ru(DIP)2 (3-methoxysq)](PF6 ), where DIP is 4,7-diphenyl-1,10-phenanthroline, sq=semiquinonate and 3-methoxysq=3-methoxysemiquinonate, form colloids in water-DMSO (1 % v/v) mixtures that are invisible to the naked eyes. [Ru(DIP)2 (3-methoxysq)](PF6 ) was found to form a highly stable and monodispersed colloid with nanoaggregates of ∼25 nm. In contrast, [Ru(DIP)2 (sq)](PF6 ) was found to form large reticulates of mostly spherical aggregates which size was found to increase over time. The difference in size and shape distribution of drug candidates is of tremendous significance as the study of their biological activity might be severely affected. Overall, we strongly believe that these observations should be taken into account by the scientific community working on the development of metal-based drugs with poor water solubility.

Cancer-Targeting Functionalization of Selenium-Containing Ruthenium Conjugate with Tumor Microenvironment-Responsive Property to Enhance Theranostic Effects.

A mutifunctional ruthenium-based conjugate Ru-BSe was designed and synthesized. The Ru complex with favorable bioimaging function was covalently linked with a cancer-targeted molecule that could be effectively internalized by the tumor to realize enhanced theranostic effects. The pH-response of the Ru conjugate in tumor acidic microenvironment causes ligand substitution and release of therapeutic complex. This activated complex remains inert to the reducing biomolecule-glutathione and terminally locates in mitochondria, in which it triggers oxidative stress, and activates intrinsic apoptosis. Real-time monitoring reveals that this Ru conjugate could selectively accumulate in tumor tissue in vivo, which significantly suppresses tumor progression and alleviate the damage to normal organs, realizing the precise cancer theranosis.

Ruthenium complexes/polypeptide self-assembled nanoparticles for identification of bacterial infection and targeted antibacterial research.

Bacterial infection has been a threat to human health, and so early diagnosis and treatment of bacterial infection is an urgent problem that needs to be solved. In this work, a multifunctional theranostic selenium nanoplatform (Se@PEP-Ru NPs) with early imaging diagnosis and efficient treatment of bacterial infections was designed and constructed. First, the antibacterial peptide UBI29-41 (PEP) was linked to functionalized Selenium nanoparticles (NPs), which enhanced the stability of the antimicrobial peptide and also caused the nanocomposites to specifically target bacterial infection. Ruthenium complexes with good antibacterial activity and fluorescence properties were then coated on to their outer layers. It was worth mentioning that, when the resulting nanoprobe was injected into mice by intravenous injection it was found to be sensitive to sites of bacterial infection for selective fluorescence imaging and targeted therapy. Thus, it can be used to distinguish between bacterial infection, inflammation, and tumor-induced tissue infection with high specificity. In the further antibacterial activity experiments, Ruthenium complexes showed synergistic antimicrobial activity with Se NPs, which indicated that the antibacterial activity of Se@PEP-Ru NPs was the strongest that could promote wound healing. Thus, Se@PEP-Ru NPs appears to be a promising antimicrobial with good biocompatibility, excellent selectivity, and potent antimicrobial activity.

The water soluble ruthenium(II) organometallic compound [Ru(p-cymene)(bis(3,5 dimethylpyrazol-1-yl)methane)Cl]Cl suppresses triple negative breast cancer growth by inhibiting tumor infiltration of regulatory T cells.

Ruthenium compounds have become promising alternatives to platinum drugs by displaying specific activities against different cancers and favorable toxicity and clearance properties. Here, we show that the ruthenium(II) complex [Ru(p-cymene)(bis(3,5-dimethylpyrazol-1-yl)methane)Cl]Cl (UNICAM-1) exhibits potent in vivo antitumor effects. When administered as four-dose course, by repeating a single dose (52.4mgkg-1) every three days, UNICAM-1 significantly reduces the growth of A17 triple negative breast cancer cells transplanted into FVB syngeneic mice. Pharmacokinetic studies indicate that UNICAM-1 is rapidly eliminated from kidney, liver and bloodstream thanks to its high hydrosolubility, exerting excellent therapeutic activity with minimal side effects. Immunohistological analysis revealed that the efficacy of UNICAM-1, mainly relies on its capacity to reverse tumor-associated immune suppression by significantly reducing the number of tumor-infiltrating regulatory T cells. Therefore, UNICAM-1 appears very promising for the treatment of TNBC.

Unexpected high photothemal conversion efficiency of gold nanospheres upon grafting with two-photon luminescent ruthenium(II) complexes: A way towards cancer therapy?

The design and development of functional hybrid nanomaterials is currently a topic of great interest in biomedicine. Herein we investigated the grafting of Ru(II) polypyridyl complexes onto gold nanospheres (Ru@AuNPs) to improve the particles' near infrared (NIR) absorption, and ultimately allow for application in photothermal cancer therapy. As demonstrated in this article, these ruthenium(II) complexes could indeed significantly enhance gold nanospheres' two-photon luminescence (PTL) intensity and photothermal therapy (PTT) efficiency. The best dual functional nanoparticles of this study were successfully used for real-time luminescent imaging-guided PTT in live cancer cells. Furthermore, in vivo tumor ablation was achieved with excellent treatment efficacy under a diode laser (808 nm) irradiation at the power density of 0.8 W/cm(2) for 5 min. This study demonstrates that the coupling of inert Ru(II) polypyridyl complexes to gold nanospheres allows for the enhancement of two-photon luminescence and for efficient photothermal effect.

Immobilized photosensitizers for antimicrobial applications.

Photodynamic antimicrobial chemotherapy (PACT) is a very promising alternative to conventional antibiotics for the efficient inactivation of pathogenic microorganisms; this is due to the fact that it is virtually impossible for resistant strains to develop due to the mode of action employed. PACT employs a photosensitizer, which preferentially associates with the microorganism, and is then activated with non-thermal visible light of appropriate wavelength(s) to generate high localized concentrations of reactive oxygen species (ROS), inactivating the microorganism. The concept of using photosensitizers immobilized on a surface for this purpose is intended to address a range of economic, ecological and public health issues. Photosensitising molecules that have been immobilized on solid support for PACT applications are described herein. Different supports have been analyzed as well as the target microorganism and the effectiveness of particular combinations of support and photosensitizer.

In vitro and in vivo evaluation of water-soluble iminophosphorane ruthenium(II) compounds. A potential chemotherapeutic agent for triple negative breast cancer.

A series of organometallic ruthenium(II) complexes containing iminophosphorane ligands have been synthesized and characterized. Cationic compounds with chloride as counterion are soluble in water (70-100 mg/mL). Most compounds (especially highly water-soluble 2) are more cytotoxic to a number of human cancer cell lines than cisplatin. Initial mechanistic studies indicate that the cell death type for these compounds is mainly through canonical or caspase-dependent apoptosis, nondependent on p53, and that the compounds do not interact with DNA or inhibit protease cathepsin B. In vivo experiments of 2 on MDA-MB-231 xenografts in NOD.CB17-Prkdc SCID/J mice showed an impressive tumor reduction (shrinkage) of 56% after 28 days of treatment (14 doses of 5 mg/kg every other day) with low systemic toxicity. Pharmacokinetic studies showed a quick absorption of 2 in plasma with preferential accumulation in the breast tumor tissues when compared to kidney and liver, which may explain its high efficacy in vivo.

Searching for new chemotherapies for tropical diseases: ruthenium-clotrimazole complexes display high in vitro activity against Leishmania major and Trypanosoma cruzi and low toxicity toward normal mammalian cells.

Eight new ruthenium complexes of clotrimazole (CTZ) with high antiparasitic activity have been synthesized, cis,fac-[Ru(II)Cl(2)(DMSO)(3)(CTZ)] (1), cis,cis,trans-[Ru(II)Cl(2)(DMSO)(2)(CTZ)(2)] (2), Na[Ru(III)Cl(4)(DMSO)(CTZ)] (3), Na[trans-Ru(III)Cl(4)(CTZ)(2)] (4), [Ru(II)(η(6)-p-cymene)Cl(2)(CTZ)] (5), [Ru(II)(η(6)-p-cymene)(bipy)(CTZ)][BF(4)](2) (6), [Ru(II)(η(6)-p-cymene)(en)(CTZ)][BF(4)](2) (7), and [Ru(II)(η(6)-p-cymene)(acac)(CTZ)][BF(4)] (8) (bipy = bipyridine; en = ethlylenediamine; acac = acetylacetonate). The crystal structures of compounds 4-8 are described. Complexes 1-8 are active against promastigotes of Leishmania major and epimastigotes of Trypanosoma cruzi. Most notably, complex 5 increases the activity of CTZ by factors of 110 and 58 against L. major and T. cruzi, with no appreciable toxicity to human osteoblasts, resulting in nanomolar and low micromolar lethal doses and therapeutic indexes of 500 and 75, respectively. In a high-content imaging assay on L. major-infected intraperitoneal mice macrophages, complex 5 showed significant inhibition on the proliferation of intracellular amastigotes (IC(70) = 29 nM), while complex 8 displayed some effect at a higher concentration (IC(40) = 1 µM).

[Tumor regression in malignant choroidal melanomas after transpupillary thermotherapy (TTT) versus ruthenium brachytherapy and sandwich therapy - a comparative analysis]. / Tumorregression maligner Aderhautmelanome nach Transpupillarer Thermotherapie (TTT) versus Ruthenium-Brachytherapie und Sandwichtherapie - eine vergleichende Analyse.

PURPOSE: The aim of this study was to evaluate tumour regression in a large series of choroidal melanomas, which were treated with three different eye-sparing treatment modalities. PATIENTS AND METHODS: Retrospective review of the treatment results in all eyes with malignant choroidal melanoma, which were treated in the University Eye Clinic of Mainz consecutively in the time span 1.1992 to 12.2000 with transpupillary thermotherapy (TTT, standard protocol Oosterhuis JA 1995), ruthenium brachytherapy (RB, tumor apex dose 150 Gy) or sandwich therapy (ST). One-step ST was defined as TTT followed by RB with 100 Gy tumor apex dose within 48 hours. The treatment of residual prominences with TTT secondary to RB after different time spans was called two-step ST. Follow-up was 2 years. RESULTS: 131 eyes with malignant choroidal melanoma (mean tumour thickness: 4.5 mm) were treated with RB (66 eyes), TTT (26 eyes) or ST (39 eyes). Preservation of the globe was achieved in 109 eyes (81 %). Local tumour control was found in small melanomas (prominence up to 3 mm) in 89 %, in large tumors (prominence 8 mm and higher) in 50 %. In a subgroup of small posterior melanomas (n = 70 eyes, prominence up to 4.5 mm, located posterior to the equator) local tumour control was noted in 91 %. The time span to reach local tumour control (Kaplan-Meier estimates) was the shortest after TTT (median: 20 weeks), compared with RB (48 weeks) and one-step ST (29 weeks). CONCLUSIONS: In choroidal melanomas the chance of local tumour control and preservation of the globe decreases with increase of the tumour prominence. In small choroidal melanomas with posterior location local tumour control was achieved significantly faster after TTT than after RB.

[Treatment of intraocular metastatic tumors]. / Leczenie wewnatrzgalkowych guzów przerzutowych.

PURPOSE: Analysis of the clinical picture of intraocular metastatic tumors and the results of the treatment with various methods. MATERIAL AND METHODS: Between 1994-1997 intraocular metastatic tumors were diagnosed in 14 patients (19 eyes). There were 13 females and 1 male, aged 28 to 69 years (average 50). The primary tumor in 8 patients developed in the breast, in 4 cases in the lungs, 1 in the brain, and 1 in the kidney. In all patients the primary tumor was excised, then chemotherapy was applied in 9 cases, radiotherapy in 3 cases, and hormonal treatment in 2 cases. In 7 patients the metastatic process concerned also other organs: bones, liver, lungs, hypophysis, and lymphatic glands. Metastases developed in 10 months to 11 years since the diagnosis and treatment of the primary tumor. Intraocular tumors were the most often located near the optic disc (8 cases), or near the macula (4 cases). There were usually flat tumors (in 12 cases < 5 mm in thickness), creamy white, sometimes with pigment clamping. In order, to confirm the diagnosis of the tumor, USG was always performed and in 8 cases fluorescein angiography. In all cases topical treatment was applied, which consisted of irradiation with ruthenium (106Ru) in 6 eyes (in 1 case two times), laser coagulation in 3 eyes, and thermotherapy (TTT) with diode laser in 4 eyes, combined treatment (106Ru + TTT) in 2 eyes, 106Ru and 125I brachytherapy in one eye. The dose of radiation for the apex of the tumor was 60-90 Gy (av. 65). The eyeball was enucleated in 3 patients, 4 patients received chemotherapy. 2 patients received hormonal therapy, applied together with the topical treatment. RESULTS: In the majority of cases (14 eyes), a flat scar or the significant decrease of the volume of the tumor was obtained. 8 patients died, two are currently observed, the remaining 4 do not come to the control examination, and there is no information as to their fate. CONCLUSIONS: Good results of the treatment encourage further application of brachy and thermotherapy in the treatment of intraocular metastatic tumors. It allows for the conservative treatment of the eyeball, and also useful visual acuity is retained often.

Antitumor activity of imidazolium-bisimidazole-tetrachlororuthenate (III). A representative of a new class of inorganic antitumor agents.

The antitumor activity of imidazolium-bisimidazole-tetrachlororuthenate (III) against the P388 leukemia and against the B16 melanoma was investigated. The test compound showed high activity against these tumor models. The tumor inhibiting effect was in the range or better than the effects of the compounds cyclophosphamide, cisplatin, or 5-fluorouracil, which were tested as positive controls. The effective substance is a new, water soluble, anionic, nitrogen-heterocyclic coordinated, ruthenium species, exhibiting antitumor activity.