👤 Gichumbi J

S: Mercury ions (Hg²⁺) are highly toxic and prone to bioaccumulation, showing a strong attraction to proteins and enzymes that contain sulfur. Even minute quantities of Hg²⁺ can lead to severe health issues. Given that mitochondria are a primary target organelle of Hg²⁺, it is essential to create a probe that can accurately detect Hg²⁺ within intracellular mitochondria. In this study, we developed two innovative Ir(III) complex probes that emit near-infrared light. The crystal structure of Ir2 was determined using X-ray techniques, which reveals that Ir2 contains a pyridine group capable of recognizing Hg²⁺ and targeting mitochondria, allowing for the precise identification of Hg²⁺ both in vitro and within the mitochondria of living cells. Additionally, these two novel near-infrared phosphorescent Ir(III) complexes demonstrate significant capabilities in producing ROS including singlet oxygen, ·O₂^- and ·OH, which renders them effective photosensitizers under visible light exposure for photodynamic therapy (PDT). This research offers a promising approach for detecting Hg²⁺ in vitro and in the mitochondrial microenvironment of living cells, which have some implications for the future development of pertinent transition metal complexes for mitochondria-targeted photodynamic therapy in cancer cells. Show less

Intracellular imaging of anticancer metallodrugs often relies on prelabeling with organic fluorophores, which significantly affects their physicochemical properties and intracellular distribution. On the other hand, the reported postlabeling strategies based on click-chemistry reactions require cell fixation and permeabilization. Here, this study presents a postlabeling approach based on the catalyst-free, inverse electron-demand Diels-Alder reaction (iEDDA) between a strained fluorescein-tagged bicyclononyne derivative (BCN-FAM) and half-sandwich Ir(III) complexes containing bidentate ligands comprising a tetrazine (Tz-R,R') entity. Five half-sandwich Ir(III) complexes with formula [Cp*Ir(Tz-R,R')Cl]^0/+ have been synthesized and fully characterized, including the X-ray crystal structures of three of the five derivatives. Investigations of their stability and their reactivity in aqueous solution and in a model iEDDA reaction reveal the strong influence of the tetrazine ligand structure on the chemical properties of the corresponding complexes. A highly cytotoxic metallodrug candidate (Ir-C,N_Ph,Me) is identified from biological studies, and chemical reactivity studies disclose an unusual preference for binding of methionine over cysteine. Postlabeling of Ir-C,N_Ph,Me in live HeLa cells highlights its preferential accumulation within the nucleus, suggesting its retention through covalent modifications of nuclear proteins in good agreement with other half-sandwich iridium(III) complexes. Show less

Title: A Bioactive Benzimidazole-Cyclometalated Iridium(III) Complex as an Epigenetic Regulator through Effectively Interrupting the EED-EZH2 Interaction. Abstract: Epigenetic regulation plays a fundamental role in controlling gene expression and maintaining cellular identity. Among epigenetic processes, the translocation of methyltransferases is critical for the modification of chromatin structure and transcriptional activity. The regulation of these translocation events and the mechanisms involved are complex, yet critical for understanding and manipulating epigenetic states. Therefore, novel strategies are required for detecting and visualizing the movement and interaction of methyltransferases within cells. Using enhancer of zeste homolog 2 (EZH2) methyltransferase as an example, a bifunctional compound capable of both monitoring and disrupting its translocation process is developed by targeting the protein-protein interaction (PPI) between embryonic ectoderm development (EED) and EZH2. The Ir(III) complex 1 bound enthalpically to EED and effectively inhibited the methyltransferase activity of EZH2. Moreover, disruption of the EED-EZH2 PPI led to increased transcriptional activity of P21 and P27, resulting in the suppression of triple-negative breast cancer (TNBC) cell proliferation. Excitingly, 1 suppressed tumor metastasis in a TNBC mouse model in vivo. To our knowledge, complex 1 is the first metal-based bifunctional therapeutic agent designed to probe and inhibit the EED-EZH2 PPI, highlighting the feasibility and significance of using metal complexes to monitor and influence methyltransferase translocations for therapeutic applications. Show less

A series of iridium(iii) complexes (Ir1-Ir3) with the formula [Ir(F₂ppy)₂(L)] (F₂ppy = 2-(2,4-difluoro-phenyl)pyridine, L = pyridine-2-aldoxime, 2-pyridylamidoxime and di-2-pyridylketoxime) were synthesized through the reaction of [(F₂ppy)₂Ir(μ-Cl)₂Ir(F₂ppy)₂] (SM1) and the respective ancillary ligands (L). All the complexes were characterised by FT-IR, ¹H & ¹⁹F-NMR analysis, electronic absorption-emission spectroscopy and cyclic voltammetric studies. Molecular structures of complexes Ir1 and Ir3 were determined by interpreting single crystal X-ray data. All the complexes were found to be luminescent with low quantum yields. Anticancer studies on cancer cell lines MDAMB, HT-29 and LN-229 revealed their effectiveness as antiproliferative agents. The cytotoxicity of the complexes was evaluated using the MTT assay and complex Ir2 showed activity similar to that of cisplatin towards the three cancer cells. The elevated level of reactive oxygen species (ROS) in the iridium complex-treated cancer cells further supported the antiproliferation efficacy of Ir1-Ir3. Further, the effectiveness of Ir1-Ir3 on cancer cells was established through a cell migration study and apoptotic induction assay on LN-229 and a colony formation assay on HT-29 cancer cells. Immunocytochemistry analysis of LN-229 cancer cells revealed apoptosis through the p53-dependent pathway. Show less

Modulating mitochondrial activity to regulate cancer cell homeostatic recycling presents a promising approach to overcome tumor resistance. Consequently, there is an urgent need for novel mitochondria-targeting agents and innovative strategies. We have developed [((η⁵-Cp∗)Ir(rhod)]²⁺2PF₆^- (Ir-rhod), a new mitochondria-targeted iridium complex that exhibits greater cytotoxicity towards A549R (cisplatin-resistant human lung cancer) cells compared to the ligand rhod. Ir-rhod's mitochondrial targeting ability stems from both rhodamine's inherent mitochondrial affinity and the complex's positive bivalent nature. The positively charged Ir-rhod enters cells and is drawn to mitochondria due to the high transmembrane potential in tumor cells. Notably, rhodamine enables real-time observation of Ir-rhod's dynamic distribution in vivo. Ir-rhod influences mitochondrial function, triggering tumor cell ferroptosis and apoptosis by modulating ACSL4 and GPX4. The targeting effect of Ir-rhod reduces its systemic toxicity in vivo, enhancing its biosafety profile. To our knowledge, Ir-rhod is an effective mitochondria-targeted Ir complex capable of inducing tumor cell death by disrupting mitochondrial function, offering a potent strategy to suppress cisplatin resistance in non-small cell lung cancer. Show less

Photoactivatable systems have received considerable attention in the development of diagnostics and therapeutics due to their noninvasive nature and precise spatiotemporal control. Of particular interest is the 3,6-dithio-1,2,4,5-tetrazine (S,S-tetrazine) unit, which can not only act as a photolabile protecting group for constructing photoactivatable systems but also as a bioorthogonal scaffold that enables the inverse electron-demand Diels-Alder (IEDDA) cycloaddition reaction with strained alkynes. In this study, we designed and synthesised a cyclometallated iridium(iii) complex modified with a 3-chloro-6-thio-1,2,4,5-tetrazine moiety (1) for cysteine conjugation. The complex was conjugated with an integrin-targeting peptide c(RGDfC) to afford a tumour-targeting conjugate (1-RGD) for bioimaging and photoactivated therapy. An RGD-free analogue (2) was also prepared for comparison studies. Unlike common iridium(iii) complexes, excitation of conjugate 1-RGD and complex 2 resulted in weak emission and negligible singlet oxygen (¹O₂) generation due to the quenching effect of the tetrazine unit. Upon continuous light irradiation, the S,S-tetrazine moiety in conjugate 1-RGD and complex 2 underwent efficient photodissociation, yielding thiocyanate (3) and amide (4) complexes as photoproducts with increased emission intensities and enhanced ¹O₂ generation efficiencies. Interestingly, the IEDDA cycloaddition reaction of the S,S-tetrazine-containing conjugate 1-RGD and complex 2 with (1R,8S,9s)-bicyclo[6.1.0]non-4-yn-9-ylmethanol (BCN-OH) led to significant emission enhancement. Notably, conjugate 1-RGD showed higher cellular uptake and (photo)cytotoxicity (IC_50,dark = 26 μM, IC_50,light = 0.08 μM) in U87-MG cells, which overexpress integrin, compared to MCF-7 (IC_50,dark = 52 μM, IC_50,light = 0.22 μM) and HEK293 cells (IC_50,dark > 50 μM, IC_50,light = 1.3 μM) with lower integrin levels. This work will contribute to the development of photoactivatable transition metal complexes for cancer-targeted imaging and therapy. Show less

Title: Highly effective Ru(II) and Os(II) half-sandwich complexes induce cytotoxicity in cancer cells through combined mitochondrial and endoplasmic reticulum stress. Abstract: A series of ruthenium(II) and osmium(II) half-sandwich complexes was synthesized and characterized for its potential as a new class of anticancer agents. The complexes feature polycyclic aromatic hydrocarbon (PAH)-substituted Schiff bases and were rationally designed to combine the redox-modulating MoA of half-sandwich Ru, Rh, Os and Ir complexes, connected with their ability to induce the formation of various reactive oxygen species (ROS), with the ability of PAH-substituents to target and disrupt DNA. The complexes [Ru(η6-pcym)Cl(L)]PF6 (1-4) and [Os(η6-pcym)Cl(L)]PF6 (5-8) were stable in aqueous environments, in contrast to the rapid degradation observed for the co-studied rhodium(III) (9-12) and iridium(III) (13-16) [M(η5-Cp∗)Cl(L)]PF6 complexes; L = ethane-1,2-diamine-based Schiff bases (L1-L4) bearing two terminal PAH substituents 2-naphtyl (for L1), 9-anthracenyl (for L2), 9-phenanthrenyl (L3) or 1-pyrenyl (L4); pcym = 1-methyl-4-(propan-2-yl)benzene (p-cymene), Cp∗ = pentamethylcyclopentadienyl. Biological testing demonstrated that 1-8 possess significant antiproliferative activity against various lung cancer cell lines, including those resistant to cisplatin, with Os(II) complex 5 showing the highest cytotoxicity. Treatment with these complexes led to the activation of stress-related gene pathways, including unconventional endoplasmic reticulum stress, apoptotic signalling, and mitochondrial membrane depolarization. Activation of p21/GADD45A pathway indicates DNA-damage response, as well. Notably, these complexes did not induce significant inflammatory responses, a notable advantage over cisplatin. The results highlight the potential of Ru and Os half-sandwich complexes as alternative metallodrugs, capable of overcoming platinum resistance and minimizing inflammatory side effects. This study suggests that these compounds could serve as a promising class of anticancer agents for future clinical development. Show less

Title: Aggregation-Induced Photosensitization of Long-Chain-Substituted Osmium Complexes for Lysosomes Targeting Photodynamic Therapy. Abstract: Photodynamic therapy (PDT) has been demonstrated to be an effective tool for cancer treatment. Seeking organelle-targeting photosensitizers (PSs) with robust reactive oxygen species (ROS) production is extremely in demand. Herein, we propose an aggregation-induced photosensitization strategy for effective PDT with osmium complexes. We designed and synthesized three osmium complexes (Os-Me, Os-tBu, and Os-Nonly) with ligands of different alkyl chains. In phosphate-buffered saline solution, the complex Os-Nonly formed a spherical aggregate with diameters of around 220 nm. The results from ROS assays indicate that Os-Nonly showed the highest efficiency in generating superoxide anions and singlet oxygen, demonstrating its role as a type I/II photosensitizer. Additionally, Os-Nonly specifically targeted lysosomes in 4T1 and MCF-7 cells, producing ROS in a sustained and efficient manner with high phototoxicity (IC50 = 6.999 μM in MCF-7 cells), thereby inducing cancer cell death. In 4T1-tumor-bearing mice models, Os-Nonly effectively inhibited tumor growth with a minimal impact on normal organs. Show less

Oxaliplatin is successfully used on advanced colorectal cancer to eradicate micro-metastasis, whereas its benefits in the early stages of colorectal cancer remains controversial since approximately 30% of patients experience unexpected relapses. Herein, we evaluate the efficacy of oxidative phosphorylation as a predictive biomarker of oxaliplatin response in colorectal cancer. We found that non-responding patients exhibit low oxidative phosphorylation activity, suggesting a poor prognosis. To reach this conclusion, we analyzed patient samples of individuals treated with oxaliplatin from the GSE83129 dataset, and a set of datasets validated using ROCplotter, selecting them based on their response to the drug. By analyzing multiple oxaliplatin-resistant and -sensitive cell lines, we identified oxidative phosphorylation KEGG pathways as a valuable predictive biomarker of oxaliplatin response with a high area under the curve (AUC = 0.843). Additionally, some oxidative phosphorylation-related biomarkers were validated in primary- and metastatic-derived tumorspheres, confirming the results obtained in silico. The low expression of these biomarkers is clinically relevant, indicating poor prognosis with decreased overall and relapse-free survival. This study proposes using oxidative phosphorylation-related protein expression levels as a predictor of responses to oxaliplatin-based treatments to prevent relapse and enable a more personalized therapy approach. Our results underscore the value of oxidative phosphorylation as a reliable marker for predicting the response to oxaliplatin treatment in colorectal cancer. Show less

Drug-target interaction (DTI) prediction is a relevant but challenging task in the drug repurposing field. In-silico approaches have drawn particular attention as they can reduce associated costs and time commitment of traditional methodologies. Yet, current state-of-the-art methods present several limitations: existing DTI prediction approaches are computationally expensive, thereby hindering the ability to use large networks and exploit available datasets and, the generalization to unseen datasets of DTI prediction methods remains unexplored, which could potentially improve the development processes of DTI inferring approaches in terms of accuracy and robustness. Show less

Drug-drug interactions (DDIs) can produce unpredictable pharmacological effects and lead to adverse events that have the potential to cause irreversible damage to the organism. Traditional methods to detect DDIs through biological or pharmacological analysis are time-consuming and expensive, therefore, there is an urgent need to develop computational methods to effectively predict drug-drug interactions. Currently, deep learning and knowledge graph techniques which can effectively extract features of entities have been widely utilized to develop DDI prediction methods. In this research, we aim to systematically review DDI prediction researches applying deep learning and graph knowledge. The available biomedical data and public databases related to drugs are firstly summarized in this review. Then, we discuss the existing drug-drug interactions prediction methods which have utilized deep learning and knowledge graph techniques and group them into three main classes: deep learning-based methods, knowledge graph-based methods, and methods that combine deep learning with knowledge graph. We comprehensively analyze the commonly used drug related data and various DDI prediction methods, and compare these prediction methods on benchmark datasets. Finally, we briefly discuss the challenges related to drug-drug interactions prediction, including asymmetric DDIs prediction and high-order DDI prediction. Show less

The co-administration of drugs known to interact greatly impacts morbidity, mortality, and health economics. This study aims to examine the drug-drug interaction (DDI) phenomenon with a large-scale longitudinal analysis of age and gender differences found in drug administration data from three distinct healthcare systems. Show less

Ferroptosis, a regulated form of cell death, is intricately linked to iron‑dependent lipid peroxidation. Recent evidence strongly supports the induction of ferroptosis as a promising strategy for treating cancers resistant to conventional therapies. A key player in ferroptosis regulation is ferroptosis suppressor protein 1 (FSP1), which promotes cancer cell resistance by promoting the production of the antioxidant form of coenzyme Q10. Of note, FSP1 confers resistance to ferroptosis independently of the glutathione (GSH) and glutathione peroxidase‑4 pathway. Therefore, targeting FSP1 to weaken its inhibition of ferroptosis may be a viable strategy for treating refractory cancer. This review aims to clarify the molecular mechanisms underlying ferroptosis, the specific pathway by which FSP1 suppresses ferroptosis and the effect of FSP1 inhibitors on cancer cells. Show less

Brain cancer is regarded as one of the most life-threatening forms of cancer worldwide. Oxidative stress acts to derange normal brain homeostasis, thus is involved in carcinogenesis in brain. The Nrf2/Keap1/ARE pathway is an important signaling cascade responsible for the maintenance of redox homeostasis, and regulation of anti-inflammatory and anticancer activities by multiple downstream pathways. Interestingly, Nrf2 plays a somewhat, contradictory role in cancers, including brain cancer. Nrf2 has traditionally been regarded as a tumor suppressor since its cytoprotective functions are considered to be the principle cellular defense mechanism against exogenous and endogenous insults, such as xenobiotics and oxidative stress. However, hyperactivation of the Nrf2 pathway supports the survival of normal as well as malignant cells, protecting them against oxidative stress, and therapeutic agents. Plants possess a pool of secondary metabolites with potential chemotherapeutic/chemopreventive actions. Modulation of Nrf2/ARE and downstream activities in a Keap1-dependant manner, with the aid of plant-derived secondary metabolites exhibits promise in the management of brain tumors. Current article highlights the effects of Nrf2/Keap1/ARE cascade on brain tumors, and the potential role of secondary metabolites regarding the management of the same. Show less

The NCI60 human tumor cell line screen has been in operation as a service to the cancer research community for more than 30 years. The screen operated with 96-well plates, a 2-day exposure period to test agents, and following cell fixation, a visible absorbance endpoint by the protein-staining dye sulforhodamine B. In this study, we describe the next phase of this important cancer research tool, the HTS384 NCI60 screen. Although the cell lines remain the same, the updated screen is performed with 384-well plates, a 3-day exposure period to test agents, and a luminescent endpoint to measure cell viability based upon cellular ATP content. In this study, a library of 1,003 FDA-approved and investigational small-molecule anticancer agents was screened by the two NCI60 assays. The datasets were compared with a focus on targeted agents with at least six representatives in the library. For many agents, including inhibitors of EGFR, BRAF, MEK, ERK, and PI3K, the patterns of GI50 values were very similar between the screens with strong correlations between those patterns within the dataset from each screen. However, for some groups of targeted agents, including mTOR, BET bromodomain, and NAMPRTase inhibitors, there were limited or no correlations between the two datasets, although the patterns of GI50 values and correlations between those patterns within each dataset were apparent. Beginning in January 2024, the HTS384 NCI60 screen became the free screening service of the NCI to facilitate drug discovery by the cancer research community. Significance: The new NCI60 cell line screen HTS384 shows robust patterns of response to oncology agents and substantial overlap with the classic screen, providing an updated tool for studying therapeutic agents. See related commentary by Colombo and Corsello, p. 2397. Show less

Lysosome-targeted photodynamic therapy, which enhances reactive oxygen species (ROS)-responsive tumor cell death, has emerged as a promising strategy for cancer treatment. Herein, a uridine (dU)-modified Ru(II) complex (RdU) was synthesized by click chemistry. It was found that RdU exhibits impressive photo-induced inhibition against the growth of triple-negative breast cancer (TNBC) cells in normoxic and hypoxic microenvironments through ROS production. It was further revealed that RdU induces ferroptosis of MDA-MB-231 cells under light irradiation (650 nm, 300 mW/cm²). Additional experiments showed that RdU binds to lysosomal integral membrane protein 2 (LIMP-2), which was confirmed by the fact that RdU selectively localizes in the lysosomes of MDA-MB-231 cells and significantly augments the levels of LIMP-2. Molecular docking simulations and an isothermal titration calorimetry assay also showed that RdU has a high affinity to LIMP-2. Finally, in vivo studies in tumor-bearing (MDA-MB-231 cells) nude mice showed that RdU exerts promising photodynamic therapeutic effects on TNBC tumors. In summary, the uridine-modified Ru(II) complex has been developed as a potential LIMP-2 targeting agent for TNBC treatment through enhancing ROS production and promoting ferroptosis. Show less

Liver cancer is one of the leading causes of death that motivating scientists worldwide to synthesize novel chemotherapeutics. Ru(II)-polypyridyl complexes are extensively studied for possible therapeutic and cellular applications due to their tunable coordination chemistry, structural diversity, ligand-exchange kinetics, accessible redox states, and rich photophysical or photochemical properties. Herein, we have synthesized a series of Ru(II) polypyridyl complexes [Ru^II(N^N)₂(ox)] (1-3), where ox is oxalate (C₂O₄^2-) and N^N is 1,10-phenanthroline (phen) (1), dipyrido[3,2-d:2',3'-f]quinoxaline (dpq) (2), and dipyrido[3,2,-a:2',3'-c]phenazine (dppz) (3). Oxalate (ox^2-) was opted as a bioactive dioxo ligand to prevent facile hydrolysis in aqueous media, thereby increasing the stability of the Ru(II)-polypyridyl complexes in physiological media. We thoroughly characterized all the complexes using ESI-MS, FT-IR, UV-vis, and ¹H NMR spectroscopy and other physicochemical methods. The complexes were stable under physiological conditions and under low-energy green LED light (λ_irr = 530 nm). However, the photoirradiation of complexes resulted in the efficient generation of singlet oxygen (¹O₂) as a major reactive oxygen species (ROS). The role of the extended aromatic conjugation of the N^N-donor ligands in the complexes was demonstrated by their binding propensities with CT-DNA and bovine serum albumin (BSA). Both DNA intercalation and groove binding were evidenced, while tryptophan (Trp) and tyrosine (Tyr) binding site preferences were revealed from the synchronous fluorescence spectra (SFS) of BSA. The cytotoxic profiling of the complexes performed on hepatocellular carcinoma cells (HepG2) in the dark and in the presence of green light indicated their dose-dependent cytotoxicity. The [Ru^II(N^N)₂(ox)] complexes exhibited enhanced photocytotoxicity mediated by efficient generation of cytotoxic ¹O₂ and effective interaction with DNA. All the complexes were internalized by the HepG2 liver cancer cells efficiently and localized to the cytoplasm and nucleus. The complexes exhibited potent anti-proliferative, anti-clonogenic, and anti-migratory effects on the cancer cells, suggesting their potential for therapeutic applications. Show less

Organometallic η⁶-arene ruthenium(II) complexes with 3-chloro-6-(1H-pyrazol-1-yl)pyridazine (Ru1, Ru2, and Ru5) and 3-chloro-6-(3,5-dimethyl-1H-pyrazol-1-yl)pyridazine (Ru3-4) N,N' heterocyclic and η⁶-arene (cymene (Ru1-4) or toluene (Ru 5)) have been synthesized. The ruthenium(II) complexes have common "three-legged piano-stool" pseudo-octahedral structures known for half-sandwich complexes. Evolution of their UV-Visible absorption spectra in PBS buffer or DMSO over 24 h confirmed their good solvolysis stability. Titrations of the complexes with the calf thymus DNA (CT-DNA) were monitored using UV-Visible absorption and fluorescence spectroscopies. The complexes interact moderately with CT-DNA and their binding constants are in the order of 10⁴ M^-1. Competitive binding of the complexes to a DNA-Hoechst 33,258 depicted competitive displacement of Hoechst from DNA's minor grooves. These complexes bind to glutathione forming GSH-adducts through S coordination by replacement of a halide, with the iodo-analogues having higher binding constants than the chloro-complexes. Cyclic voltammograms of the complexes exhibited one electron-transfer quasi-reversible process. Trends in the molecular docking data of Ru1-5/DNA were similar to those for DNA binding constants. Of the five, only Ru1, Ru3 and Ru5 showed some activity (moderate) against the MCF-7 breast cancer cells with IC₅₀ values in the range of 59.2-39.9 for which Ru5 was the most active. However, the more difficult-to-treat cell line, MDA-MB 231 cell was recalcitrant to the treatment by these complexes. Show less

Dysregulation of Fibroblast Growth Factor Receptors (FGFRs) signaling has been associated with breast cancer, yet employing FGFR-targeted delivery systems to improve the efficacy of cytotoxic agents is still sparsely exploited. Herein, we report four new bi-functional ruthenium-peptide conjugates (RuPCs) with FGFR-targeting and pH-dependent releasing abilities, envisioning the selective delivery of cytotoxic Ru complexes to FGFR(+)-breast cancer cells, and controlled activation at the acidic tumoral microenvironment. The antiproliferative potential of the RuPCs and free Ru complexes was evaluated in four breast cancer cell lines with different FGFR expression levels (SKBR-3, MDA-MB-134-VI, MCF-7, and MDA-MB-231) and in human dermal fibroblasts (HDF), at pH 6.8 and pH 7.4 aimed at mimicking the tumor microenvironment and normal tissues/bloodstream pHs, respectively. The RuPCs showed higher cytotoxicity in cells with higher level of FGFR expression at acidic pH. Additionally, RuPCs showed up to 6-fold higher activity in the FGFR(+) breast cancer lines compared to the normal cell line. The release profile of Ru complexes from RuPCs corroborates the antiproliferative effects observed. Remarkably, the cytotoxicity and releasing ability of RuPCs were shown to be strongly dependent on the conjugation of the peptide position in the Ru complex. Complementary molecular dynamic simulations and computational calculations were performed to help interpret these findings at the molecular level. In summary, we identified a lead bi-functional RuPC that holds strong potential as a FGFR-targeted chemotherapeutic agent. Show less

To effectively inhibit the growth and metastasis of triple-negative breast cancer (TNBC), we developed a high-efficiency and low-toxicity arene ruthenium (Ru) complex based on apoferritin (AFt). To achieve this, we optimized a series of Ru(II) 1,10-phenanthroline-2,9-diformaldehyde thiosemicarbazone complexes by studying their structure-activity relationships to obtain an arene binuclear Ru(II) complex (C5) with significant cytotoxicity and high accumulation in the mitochondria of tumor cells. Subsequently, a C5-AFt nanoparticle (NPs) delivery system was constructed. We found that the C5/C5-AFt NPs effectively inhibited TNBC growth and metastasis with few side effects. The C5-AFt NPs improved the anticancer and targeting abilities of C5 in vivo. Moreover, we confirmed the mechanism by which C5/C5-AFt NPs inhibit tumor growth and metastasis via mitochondrial damage-mediated ferroptosis and activation of the cGAS-STING pathway. Show less

A synthetic procedure was designed for the preparation and characterization of Ag and Ru complexes containing NHC ligands functionalized with PEG fragments. Stability studies were conducted to gain insight of the species in water and other solvents like DMSO, or with reagents like imidazole as representative group for histidine amino acid. The presence of Cl atoms instead of H in the 4,5 positions of the N-heterocyclic carbene afforded higher water stability. The complexes containing PEG units must be considered inactive as anticancer agents. To enhance the anticancer activity of PEG-containing complexes, the balance between hydrophilicity and hydrophobicity was adjusted using a silane moiety, and an anionic carbosilane dendrimer as a lipophilic carrier. Show less

A new family of ethacrynic acid-functionalized, chalcone-hydroxypyrone hybrid ruthenium(II)-arene complexes (4a-4e) have been designed, synthesis and fully characterized by ¹H and ¹³C NMR, ESI-MS, elemental analysis, and melting point tests. The molecular structure of 3a, one of the precursor complexes, has been determined by single-crystal X-ray diffraction. The cytotoxicity of the obtained complexes toward human cancer cell lines such as HeLa, MGC803, A549, MDA-MB-231, and MCF-7 cells have been investigated by MTT assay. Whereas complexes 4d and 4e showed significantly higher cytotoxicity than cisplatin (the positive control group) and complexes 3a-3e. Moreover, complexes 4d and 4e exhibited a certain selectivity (selectivity index: 7.33 and 7.57) toward MCF-7 cells over MCF-10a normal cells. Glutathione S-transferases (GSTs) activity assay indicate that complexes 4d and 4e exhibited higher GST inhibitory activity than ethacrynic acid (EA, the best characterized GST inhibitor), consistent with their higher cytotoxicity. Further mechanistic studies showed that 4e-induced cell apoptosis may be aroused by the production of ROS, the loss of mitochondrial membrane potential and G2/M phase cell arrest in MCF-7 cells. In addition, the in vivo antitumor effect study on the xenograft mouse models of MCF-7 cells reveal that complex 4e significantly inhibited tumor growth with a higher inhibition efficiency of 68.80 %, in comparison with the groups treated with cisplatin (59.25 %). These results highlight the strong possibility to develop positively-charged, chalcone-hydroxypyrone hybrid ruthenium(II)-arene complexes funcionalized with GST inhibitor as promising anticancer agents. Show less

Chemoresistance remains an arduous challenge in oncology, but ferroptosis shows potential for overcoming it by stimulating the immune system. Herein, a novel high-performance ruthenium(II)-based arene complex [Ru(η⁶-p-cym)(BTBpy)Cl] (RuBTB) is developed for ferroptosis-enhanced antitumor immunity and drug resistance reversal via glutathione (GSH) metabolism imbalance. RuBTB shows significantly enhanced antiproliferation activity against cisplatin (CDDP)-resistant lung cancer cells (A549R), with 26.35-fold better anticancer effects than CDDP. Immunogenic ferroptosis is induced by GSH depletion/glutathione peroxidase 4 (GPX4) inactivation, mitochondrial dysfunction, and endoplasmic reticulum (ER) stress in RuBTB-treated cells. Mechanism studies indicate that RuBTB regulates ferroptosis and immune-related pathways, coordinating with GSH metabolism-mediated glutathione S-transferase (GST) inhibition to reverse drug resistance in platinum-combined therapy. Tumor vaccination experiments demonstrate the intensified antitumor effects endowed by highly immunogenic ferroptosis in vivo. This study provides the first example of a metal-arene complex for achieving satisfactory ferroptosis therapeutic effects with efficient immunogenicity to overcome drug resistance in metal-based immunochemotherapy. Show less

Herein, we describe and investigate biological activity of three octahedral ruthenium(II) complexes of the type [Ru(C^∧N)(phen)₂]⁺, RuL1-RuL3, containing a π-expansive cyclometalating substituted benzo[g]quinoxaline ligand (C^∧N ligand) (phen = 1,10-phenanthroline). Compounds RuL1-RuL3 in cervical, melanoma, and colon human cancer cells exhibit high phototoxicity after irradiation with light (particularly blue), with the phototoxicity index reaching 100 for the complex RuL2 in most sensitive HCT116 cells. RuL2 accumulates in the cellular membranes. If irradiated, it induces lipid peroxidation, likely connected with photoinduced ROS generation. Oxidative damage to the fatty acids leads to the attenuation of the membranes, the activation of caspase 3, and the triggering of the apoptotic pathway, thus implementing membrane-localized photodynamic therapy. RuL2 is the first photoactive ruthenium-based complex capable of killing the hardly treatable colon cancer stem cells, a highly resilient subpopulation within a heterogeneous tumor mass, responsible for tumor recurrence and the metastatic progression of cancer. Show less

Title: Insights into the anticancer photodynamic activity of Ir(III) and Ru(II) polypyridyl complexes bearing β-carboline ligands. Abstract: Ir(III) and Ru(II) polypyridyl complexes are promising photosensitizers (PSs) for photodynamic therapy (PDT) due to their outstanding photophysical properties. Herein, one series of cyclometallated Ir(III) complexes and two series of Ru(II) polypyridyl derivatives bearing three different thiazolyl-β-carboline N^N' ligands have been synthesized, aiming to evaluate the impact of the different metal fragments ([Ir(C^N)2]+ or [Ru(N^N)2]2+) and N^N' ligands on the photophysical and biological properties. All the compounds exhibit remarkable photostability under blue-light irradiation and are emissive (605 < λem < 720 nm), with the Ru(II) derivatives displaying higher photoluminescence quantum yields and longer excited state lifetimes. The Ir PSs display pKa values between 5.9 and 7.9, whereas their Ru counterparts are less acidic (pKa > 9.3). The presence of the deprotonated form in the Ir-PSs favours the generation of reactive oxygen species (ROS) since, according to theoretical calculations, it features a low-lying ligand-centered triplet excited state (T1 = 3LC) with a long lifetime. All compounds have demonstrated anticancer activity. Ir(III) complexes 1-3 exhibit the highest cytotoxicity in dark conditions, comparable to cisplatin. Their activity is notably enhanced by blue-light irradiation, resulting in nanomolar IC50 values and phototoxicity indexes (PIs) between 70 and 201 in different cancer cell lines. The Ir(III) PSs are also activated by green (with PI between 16 and 19.2) and red light in the case of complex 3 (PI = 8.5). Their antitumor efficacy is confirmed by clonogenic assays and using spheroid models. The Ir(III) complexes rapidly enter cells, accumulating in mitochondria and lysosomes. Upon photoactivation, they generate ROS, leading to mitochondrial dysfunction and lysosomal damage and ultimately cell apoptosis. Additionally, they inhibit cancer cell migration, a crucial step in metastasis. In contrast, Ru(II) complex 6 exhibits moderate mitochondrial activity. Overall, Ir(III) complexes 1-3 show potential for selective light-controlled cancer treatment, providing an alternative mechanism to chemotherapy and the ability to inhibit lethal cancer cell dissemination. Show less

Title: Biomolecular Interactions and Anticancer Mechanisms of Ru(II)-Arene Complexes of Cinnamaldehyde-Derived Thiosemicarbazone Ligands: Analysis Combining In Silico and In Vitro Approaches. Abstract: Our study focuses on synthesizing and exploring the potential of three N-(4) substituted thiosemicarbazones derived from cinnamic aldehyde, alongside their Ru(II)-(η6 -p-cymene)/(η6-benzene) complexes. The synthesized compounds were comprehensively characterized using a range of analytical techniques, including FT-IR, UV-visible spectroscopy, NMR (1H, 13C), and HRMS. We investigated their electronic and physicochemical properties via density functional theory (DFT). X-ray crystal structures validated structural differences identified by DFT. Molecular docking predicted promising bioactivities, supported by experimental observations. Notably, docking with EGFR suggested an inhibitory potential against this cancer-related protein. Spectroscopic titrations revealed significant DNA/BSA binding affinities, particularly with DNA intercalation and BSA hydrophobic interactions. RuPCAM displayed the strongest binding affinity with DNA (Kb = 6.23 × 107 M-1) and BSA (Kb = 9.75 × 105 M-1). Assessed the cytotoxicity of the complexes on cervical cancer cells (HeLa), and breast cancer cells (MCF-7 and MDA-MB 231), revealing remarkable potency. Additionally, selectivity was assessed by examining MCF-10a normal cell lines. The active complexes were found to trigger apoptosis, a vital cellular process crucial for evaluating their potential as anticancer agents utilizing staining assays and flow cytometry analysis. Intriguingly, complexation with Ru(II)-arene precursors significantly amplified the bioactivity of thiosemicarbazones, unveiling promising avenues toward the creation of powerful anticancer agents. Show less

Ruthenium complexes are one of the most promising anticancer drugs and ferroptosis is a novel form of regulated cell death, the study on the effect of Ru complexes on ferroptosis is helpful to find more effective antitumor drugs. Here, the synthesis and characterization of two Ru complexes containing 8-hydroxylquinoline and triphenylphosphine as ligands, [Ru(L₁) (PPh₃)₂Cl₂] (Ru-1), [Ru(L₂) (PPh₃)₂Cl₂] (Ru-2), were reported. Complexes Ru-1 ∼ Ru-2 showed good anticancer activity in Hep-G2 cells. Researches indicated that complexes Ru-1 ∼ Ru-2 could be enriched and appear as red fluorescence in the mitochondria, arouse dysfunction of mitochondria, induce the accumulation of reactive oxygen species (ROS) and lipid peroxidation (LPO), while the morphology of nuclei and cell apoptosis had no significant change. Further experiments proved that GPX4 and Ferritin were down-regulated, which eventually triggered ferroptosis in Hep-G2 cells. Remarkably, Ru-1 showed high inhibitory activity against xenograft tumor growth in vivo (TGIR = 49%). This study shows that the complex Ru-1 could act as a novel drug candidate by triggering cell ferroptosis. Show less

Metastatic cancer remains a formidable challenge in anticancer therapy. Despite efforts to develop effective antimetastasis drugs over the past half-century, currently approved treatments fall short of expectations. This report highlights the promising antiproliferative activity of a ruthenium-based therapeutic agent, namely dichlorido(p-cymene)[2-amino-4-(pyridin-3-yl)-4H-benzo[h]-chromene-3-carbonitrile]ruthenium(II) (complex 1) against metastatic cell lines. Complex 1 shows significant efficacy in metastatic LoVo and Du-145 cell lines at nanomolar concentrations, being markedly more active than clinically used anticancer cisplatin. Studies on the MDA-MB-231 cell line, which displays invasive characteristics, demonstrated that 1 significantly reduces cell invasion. This efficacy was confirmed by its impact on matrix metalloproteinase production in MDA-MB-231 cells. Given that cell migration drives cancer invasion and metastasis, complex 1's effect on MDA-MB-231 cell migration was evaluated via wound healing assay and vimentin network analysis. Results indicated a strong reduction in migration. A re-adhesion assay further demonstrated that 1 significantly lowers the re-adhesion ability of MDA-MB-231 cells compared to cisplatin. To better simulate the human body environment, a 3D spheroid invasion assay was used. This method showed that 1 effectively inhibits tumor spheroids from infiltrating the surrounding extracellular matrix. This study underscores the potential of (arene)ruthenium(II) complexes with naphthopyran ligands as potent antimetastatic agents for chemotherapy. Show less

Despite advances in Ir(III) and Ru(II) photosensitizers (PSs), their lack of selectivity for cancer cells has hindered their use in photodynamic therapy (PDT). We disclose the synthesis and characterization of two pairs of Ir(III) and Ru(II) polypyridyl complexes bearing two β-carboline ligands (N^N') functionalized with -COOMe (L1) or -COOH (L2), resulting in PSs of formulas [Ir(C^N)₂(N^N')]Cl (Ir-Me: C^N = ppy, N^N' = L1; Ir-H: C^N = ppy, N^N' = L2) and [Ru(N^N)₂(N^N')](Cl)₂ (Ru-Me: N^N = bpy, N^N' = L1; Ru-H: N^N = bpy, N^N' = L2). To enhance their selectivity toward cancer cells, Ir-H and Ru-H were coupled to a bombesin derivative (BN3), resulting in the metallopeptides Ir-BN and Ru-BN. Ir(III) complexes showed higher anticancer activity than their Ru(II) counterparts, particularly upon blue light irradiation, but lacked cancer cell selectivity. In contrast, Ir-BN and Ru-BN exhibited selective photocytoxicity against prostate cancer cells, with a lower effect against nonmalignant fibroblasts. All compounds generated ROS and induced severe mitochondrial toxicity upon photoactivation, leading to apoptosis. Additionally, the ability of Ir-Me to oxidize NADH was demonstrated, suggesting a mechanism for mitochondrial damage. Our findings indicated that the conjugation of metal PSs with BN3 creates efficient PDT agents, achieving selectivity through targeting bombesin receptors and local photoactivation. Show less