Oncosis-inducing cyclometalated iridium(iii) complexes

Anticancer behavior of cyclometallated iridium(III)-tributyltin(IV) carboxylate schiff base complexes with aggregation-induced emission

Cyclometallated iridium(III) and organotin(IV) carboxylate complexes have shown potential application value in the field of anticancer. However, the widespread aggregation-caused quenching (ACQ) effect of these complexes is not conducive to the exploration of their targeting and anticancer mechanism, and the idea of aggregation-induced emission (AIE) effect can effectively solve this problem. Then, AIE-activated cyclometallated iridium(III)-tributyltin(IV) carboxylate Schiff base complexes were designed and prepared in this study. Complexes exhibited AIE effect in highly concentrated solution or aggregative state, which facilitated the investigation of subcellular tissue targeting (mitochondria) and cell morphology. Compared with cyclometallated iridium(III) complex and tributyltin(IV) carboxylate monomers, these complexes showed the better in-vitro anti-proliferative activity toward A549 cells, confirming the favorable synergistic anticancer activity. Even for A549/DDP (cisplatin-resistance) cells, these complexes also exhibited the better activity. In addition, complexes showed a mitochondrial apoptotic pathway. Therefore, cyclometallated iridium(III)-tributyltin(IV) carboxylate Schiff base complexes can be used as the potential substitutes for platinum-based drugs and gain further application.

Endoplasmic reticulum-targeted iridium(III) photosensitizer induces pyroptosis for augmented tumor immunotherapy

An ideal tumor treatment strategy involves therapeutic approaches that can enhance the immunogenicity of the tumor microenvironment while simultaneously eliminating the primary tumor. A cholic acid-modified iridium(III) (Ir3) photosensitizer, targeted to the endoplasmic reticulum (ER), has been reported to exhibit potent type I and type II photodynamic therapeutic effects against triple-negative breast cancer (MDA-MB-231). This photosensitizer induces pyroptotic cell death mediated by gasdermin E (GSDME) through photodynamic means and enhances tumor immunotherapy. Mechanistic studies have revealed that complex Ir3 induces characteristics of damage-related molecular patterns (DAMPs) in MDA-MB-231 breast cancer cells under light conditions. These include cell-surface calreticulin (CRT) eversion, extracellular high mobility group box 1 (HMGB1) and ATP release, accompanied by ER stress and increased reactive oxygen species (ROS). Consequently, complex Ir3 promotes dendritic cell maturation and antigen presentation under light conditions, fully activates T cell-dependent immune response in vivo, and ultimately eliminates distant tumors while destroying primary tumors. In conclusion, immune regulation and targeted intervention mediated by metal complexes represent a new and promising approach to tumor therapy. This provides an effective strategy for the development of combined targeted therapy and immunotherapy.

Iridium(III) complexes as novel theranostic small molecules for medical diagnostics, precise imaging at a single cell level and targeted anticancer therapy

Medical applications of iridium (III) complexes include their use as state-of-the-art theranostic agents - molecules that combine therapeutic and diagnostic functions into a single entity. These complexes offer a promising avenue in medical diagnostics, precision imaging at single-cell resolution and targeted anticancer therapy due to their unique properties. In this review we report a short summary of their application in medical diagnostics, imaging at single-cell level and targeted anticancer therapy. The exceptional photophysical properties of Iridium (III) complexes, including their brightness and photostability, make them excellent candidates for bioimaging. They can be used to image cellular processes and the microenvironment within single cells with unprecedented clarity, aiding in the understanding of disease mechanisms at the molecular level. Moreover the iridium (III) complexes can be designed to selectively target cancer cells,. Upon targeting, these complexes can act as photosensitizers for photodynamic therapy (PDT), generating reactive oxygen species (ROS) upon light activation to induce cell death. The integration of diagnostic and therapeutic capabilities in Iridium (III) complexes offers the potential for a holistic approach to cancer treatment, enabling not only the precise eradication of cancer cells but also the real-time monitoring of treatment efficacy and disease progression. This aligns with the goals of personalized medicine, offering hope for more effective and less invasive cancer treatment strategies.

Insights into the antineoplastic activity and mechanisms of action of coumarin-coordinated 8-hydroxyquinoline ruthenium(II/III) compounds

Ruthenium(II/III) coordination compounds have gained widespread attention as chemotherapy drugs, photosensitizers, and photodynamic therapy reagents. Herein, a family of 11 novel coumarin-coordinated 8-hydroxyquinoline ruthenium(II/III) compounds, i.e., [RuII2(μ2-Cl)2(QL1a)2(DMSO)4] (YNU-4a = Yulin Normal University-4a), [RuII2(μ2-Cl)2(QL1b)2(DMSO)4] (YNU-4b), [RuII2(μ2-Cl)2(QL1c)2(DMSO)4] (YNU-4c), [RuII2(μ2-Cl)2(QL1d)2(DMSO)4]⋅2CH3OH (YNU-4d), [RuII(QL1e)2(DMSO)2] (YNU-4e), [RuIII(QL1e)2(QL3a)] (YNU-4f), [RuIII(QL1e)2(QL3b)] (YNU-4g), [RuIII(QL1e)2(QL3c)] (YNU-4h), [RuIICl2(H-QL3a)2(DMSO)2] (YNU-4i), [RuIICl2(H-QL3b)2(DMSO)2] (YNU-4j), and [RuIICl2(H-QL3c)2(DMSO)2] (YNU-4k), featuring the coligands 5,7-diiodo-8-hydroxyquinoline (H-QL1a), 5,7-dichloro-8-quinolinol (H-QL1b), 5-chloro-7-iodo-8-hydroxyquinolin (H-QL1c), 5,7-dibromo-8-hydroxyquinoline (H-QL1d), and 5,7-dichloro-8-hydroxy-2-methylquinoline (H-QL1e) and the main ligands 6,7-dichloro-3-pyridin-2-yl-chromen-2-one (H-QL3a), 6-bromo-3-pyridin-2-yl-chromen-2-one (H-QL3b), and 6-chloro-3-pyridin-2-yl-chromen-2-one (H-QL3c), respectively. The structure of compounds YNU-4a-YNU-4k was fully confirmed by conducting various spectroscopic analyses. The anticancer activity of YNU-4a-YNU-4k was evaluated in cisplatin-resistant A549/DDP lung cancer cells (LC549) versus normal embryonic kidney (HEK293) cells. Notably, compound YNU-4f bearing QL1e and QL3a ligands showed a more pronounced antiproliferative effect against LC549 cells (IC50 = 1.75 ± 0.09 μM) with high intrinsic selectivity toward LC549 cancer cells than YNU-4a-YNU-4e, H-QL1a-H-QL1e, cisplatin (PDD), YNU-4g-YNU-4k, and H-QL3a-H-QL3c. Additionally, a colocalization assay analysis of YNU-4e and YNU-4f showed that these two ruthenium(II/III) compounds were subcellularly accumulated in the mitochondria and other regions of the cytoplasm, where they induce mitophagy, adenosine triphosphate (ATP) reduction, mitochondrial respiratory chain complex I/IV(RC1/RC4) inhibition, and mitochondrial dysfunction. Accordingly, compounds YNU-4a-YNU-4k can be regarded as mitophagy inductors for the eradication of cisplatin-resistant LC549 cancer cells.

White light increases anticancer effectiveness of iridium(III) complexes toward lung cancer A549 cells

Anticancer activity has been extensively studies. In this article, three ligands 2-(6-bromobenzo[d][1,3]dioxol-5-yl)-1H-imidazo[4,5-f][1,10]phenanthroline (BDIP), 2-(7-methoxybenzo[d][1,3]dioxol-5-yl)-1H-imidazo[4,5-f][1,10]phenanthroline (MDIP), 2-(6-nitrobenzo[d][1,3]dioxol-5-yl)-1H-imidazo[4,5-f][1,10]phenanthroline (NDIP) and their iridium(III) complexes: [Ir(ppy)2(BDIP)](PF6) (ppy = deprotonated 2-phenylpyridine, 3a), [Ir(ppy)2(MDIP)](PF6) (3b) and [Ir(ppy)2(NDIP)](PF6) (3c) were synthesized. The cytotoxicity of 3a, 3b, 3c against Huh7, A549, BEL-7402, HepG2, HeLa, and non-cancer NIH3T3 was tested using 3-(4,5-dimethylthiazole-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) method. The results obtained from the MTT test stated clearly that these complexes demonstrated moderate or non-cytotoxicity toward Huh7, BEL-7402, HepG2 and HeLa except A549 cells. To improve the anticancer efficacy, we used white light to irradiate the mixture of cells and complexes for 30 min, the anticancer activity of the complexes was greatly enhanced. Particularly, 3a and 3b exhibited heightened capability to inhibit A549 cells proliferation with IC50 (half maximal inhibitory concentration) values of 0.7 ± 0.3 μM and 1.8 ± 0.1 μM, respectively. Cellular uptake has shown that 3a and 3b can be accumulated in the cytoplasm. Wound healing and colony forming showed that 3a and 3b significantly hinder the cell migration and growth in the S phase. The complexes open mitochondrial permeability transition pore (MPTP) channel and cause the decrease of membrane potential, release of cytochrome C, activation of caspase 3, and finally lead to apoptosis. In addition, 3a and 3b cause autophagy, increase the lipid peroxidation and lead to ferroptosis. Also, 3a and 3b increase the expression of calreticulin (CRT), high mobility group box 1 (HMGB1), heat shock protein 70 (HSP70), thereby inducing immunogenic cell death.

Photoinduction of Ferroptosis and cGAS-STING Activation by a H2S-Responsive Iridium(III) Complex for Cancer-Specific Therapy

Triggering ferroptosis represents a promising anticancer therapeutic strategy, but the development of a selective ferroptosis inducer for cancer-specific therapy remains a great challenge. Herein, a H2S-responsive iridium(III) complex NA-Ir has been well-designed as a ferroptosis inducer. NA-Ir could selectively light up H2S-rich cancer cells, primarily localize in mitochondria, intercalate into mitochondrial DNA (mtDNA), and induce mtDNA damage, exhibiting higher anticancer activity under light irradiation. Mechanistic studies showed that NA-Ir-mediated PDT triggered lipid peroxidation and glutathione peroxidase 4 downregulation through ROS production and GSH depletion, resulting in ferroptosis through multiple pathways. Moreover, the intense mtDNA damage can activate the cyclic GMP-AMP synthase-stimulator of the interferon gene (cGAS-STING) pathway, leading to ferritinophagy and further ferroptosis. RNA-sequencing analysis showed that NA-Ir-mediated PDT mainly affects the expression of genes related to ferroptosis, autophagy, and cancer immunity. This study demonstrates the first cancer-specific example with ferroptosis and cGAS-STING activation, which provides a new strategy for multimodal synergistic therapy.

Pt(II) Bis(pyrrole-imine) complexes: Luminescent probes and cytotoxicity in MCF-7 cells†

Four Pt(II) bis(pyrrole-imine) Schiff base chelates (1-4) were synthesised by previously reported methods, through a condensation reaction, and the novel crystal structure of 2,2'-{propane-1,3-diylbis[nitrilo(E)methylylidene]}bis(pyrrol-1-ido)platinum(II) (1) was obtained. Pt(II) complexes 1-4 exhibited phosphorescence, with increased luminescence in anaerobic solvents or when bound to human serum albumin (HSA). One of the complexes shows a 15.6-fold increase in quantum yield when bound to HSA and could be used to detect HSA concentrations as low as 5 nM. Pt(II) complexes 1-3 was investigated as potential theranostic agents in MCF-7 breast cancer cells, but only complex 3 exhibited cytotoxicity when irradiated with UV light (λ355nmExcitation). Interestingly, the cytotoxicity of complex 1 was unresponsive to UV light irradiation. This indicates that only complex 3 can be considered a potential photosensitising agent.

Unravelling oncosis: morphological and molecular insights into a unique cell death pathway

Programmed cell death (PCD) is a fundamental biological process for maintaining cellular equilibrium and regulating development, health, and disease across all living organisms. Among the various types of PCD, apoptosis plays a pivotal role in numerous diseases, notably cancer. Cancer cells frequently develop mechanisms to evade apoptosis, increasing resistance to standard chemotherapy treatments. This resistance has prompted extensive research into alternative mechanisms of programmed cell death. One such pathway is oncosis, characterized by significant energy consumption, cell swelling, dilation of the endoplasmic reticulum, mitochondrial swelling, and nuclear chromatin aggregation. Recent research suggests that oncosis can impact conditions such as chemotherapeutic cardiotoxicity, myocardial ischemic injury, stroke, and cancer, mediated by specific oncosis-related proteins. In this review, we provide a detailed examination of the morphological and molecular features of oncosis and discuss various natural or small molecule compounds that can induce this type of cell death. Additionally, we summarize the current understanding of the molecular mechanisms underlying oncosis and its role in both normal physiology and pathological conditions. These insights aim to illuminate future research directions and propose innovative strategies for leveraging oncosis as a therapeutic tool against human diseases and cancer resistance.

Design and anticancer behaviour of cationic/neutral half-sandwich iridium(III) imidazole-phenanthroline/phenanthrene complexes

Considerable attention has been devoted to the exploration of organometallic iridium(III) (IrIII) complexes for their potential as metallic anticancer drugs. In this study, twelve half-sandwich IrIII imidazole-phenanthroline/phenanthrene complexes were prepared and characterized. Complexes exhibited promising in-vitro anti-proliferative activity, and some are obviously superior to cisplatin towards A549 cells. These complexes possessed suitable fluorescence, and a non-energy-dependent uptake pathway was identified, subsequently leading to their accumulation in the lysosome and the lysosomal damage. Additionally, complexes could inhibit the cell cycle (G1-phase) and catalyze intracellular NADH oxidation, thus substantiating the elevation of intracellular reactive oxygen species (ROS) level, which confirming the oxidative mechanism. Western blotting further confirmed that complexes could induce A549 cell apoptosis through the lysosomal-mitochondrial anticancer pathway, which was inconsistent with cisplatin. In summary, these complexes offer fresh concepts for the development of organometallic non‑platinum anticancer drugs.

Mitochondria-Targeting Metallodrugs for Cancer Therapy: Perspectives from Cell Death Modes

Mitochondria, recognized as the cellular powerhouses, are indispensable organelles responsible for crucial cellular processes, such as energy metabolism, material synthesis, and signaling transduction. Their intricate involvement in a broad spectrum of diseases, particularly cancer, has propelled the exploration of mitochondria-targeting treatment as a promising strategy for cancer therapy. Since the groundbreaking discovery of cisplatin, the trajectory of research on the development of metal complexes have been marked by continuous advancement, giving rise to a diverse array of metallodrugs characterized by variations in ligand types, metal center properties, and oxidation states. By specifically targeting mitochondria, these metallodrugs exhibit the remarkable ability to elicit various programmed cell death pathways, encompassing apoptosis, autophagy, and ferroptosis. This review primarily focuses on recent developments in transition metal-based mitochondria-targeting agents, offering a comprehensive exploration of their capacity to induce distinct cell death modes. The aim is not only to disseminate knowledge but also to stimulate an active field of research toward new clinical applications and novel anticancer mechanisms.

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.

Anticancer Potential of the S-Heterocyclic Ring Containing Drugs and its Bioactivation to Reactive Metabolites

Sulfur-containing heterocyclic derivatives have been disclosed for binding with a wide range of cancer-specific protein targets. Various interesting derivatives of sulfur-containing heterocyclics such as benzothiazole, thiazole, thiophene, thiazolidinedione, benzothiophene, and phenothiazine, etc have been shown to inhibit diverse signaling pathways implicated in cancer. Significant progress has also been made in molecular targeted therapy against specific enzymes such as kinase receptors due to potential binding interactions inside the ATP pocket. Sulfur-containing heterocyclic ring metal complexes i. e., benzothiazole, thiazole, thiophene, benzothiophene and phenothiazines are among the most promising active anticancer compounds. However, sulfur heteroaromatic rings, particularly thiophene, are of high structural alert due to their metabolism to reactive metabolites. The mere presence of a structural alert itself does not determine compound toxicity therefore, this review focuses on some specific findings that shed light on factors influencing the toxicity. In the current review, synthetic strategies of introducing the sulfur core ring in the synthesized derivatives are discussed with their structure-activity relationships to enhance our understanding of toxicity mechanisms and develop safer therapeutic options. The sulfur-containing marketed anticancer drugs included in this review direct the synthesis of novel compounds and will help in the development of potent, safer sulfur-based anticancer drugs in near future.

Iridium(III) complexes conjugated with naproxen exhibit potent anti-tumor activities by inducing mitochondrial damage, modulating inflammation, and enhancing immunity

A series of Ir(III)-naproxen (NPX) conjugates with the molecular formula [Ir(C^N)2bpy(4-CH2ONPX-4'-CH2ONPX)](PF6) (Ir-NPX-1-3) were designed and synthesized, including C^N = 2-phenylpyridine (ppy, Ir-NPX-1), 2-(2-thienyl)pyridine (thpy, Ir-NPX-2) and 2-(2,4-difluorophenyl)pyridine (dfppy, Ir-NPX-3). Cytotoxicity tests showed that Ir-NPX-1-3 exhibited excellent antitumor activity, especially in A549R cells. The cellular uptake experiment showed that the complexes were mainly localized in mitochondria, and induced apoptosis in A549R cells by damaging the structure and function of mitochondria. The main manifestations are a decrease in the mitochondrial membrane potential (MMP), an increase in reactive oxygen species (ROS) levels, and cell cycle arrest. Furthermore, Ir-NPX-1-3 could inhibit the migration and colony formation of cancer cells, demonstrating potential anti-metastatic ability. Finally, the anti-inflammatory and immunological applications of Ir-NPX-1-3 were verified. The downregulation of cyclooxygenase-2 (COX-2) and programmed death-ligand 1 (PD-L1) expression levels and the release of immunogenic cell death (ICD) related signaling molecules such as damage-associated molecular patterns (DAMPs) (cell surface calreticulin (CRT), high mobility group box 1 (HMGB1), and adenosine triphosphate (ATP)) indicate that these Ir(III) -NPX conjugates are novel ICD inducers with synergistic effects in multiple anti-tumor pathways.

Consolidating Organometallic Complex Empowers Mitochondria-Directed Chemotherapy against Resistant Cancer via Stemness and Metastasis Inhibition

Cancer treatment has faced severe obstacles due to the smart biological system of cancer cells. Herein, we report a three-in-one agent Ir-CA via attenuation of cancer cell stemness with the down-regulated biomarker CD133 expression from the mitochondria-directed chemotherapy. Over 80% of Ir-CA could accumulate in mitochondria, result in severe mitochondrial dysfunctions, and subsequently initiate mitophagy and cell cycle arrest to kill cisplatin-resistant A549R cells. In vitro and in vivo antimetastatic experiments demonstrated that Ir-CA can effectively inhibit metastasis with down-regulated MMP-2/MMP-9. RNA seq analysis and Western blotting indicated that Ir-CA also suppresses the GSTP1 expression to decrease the intracellular Pt-GS adducts, resulting in the detoxification and resensitization to cisplatin of A549R cells. In vivo evaluation indicated that Ir-CA restrains the tumor growth and has minimal side effects and superior biocompatibility. This work not only provides the first three-in-one agent to attenuate cancer cell stemness and simultaneously realize anticancer, antimetastasis, and conquer metallodrug resistance but also demonstrates the effectiveness of the mitochondria-directed strategy in cancer treatment.

Designing a Mitochondria-Targeted Theranostic Cyclometalated Iridium(III) Complex: Overcoming Cisplatin Resistance and Inhibiting Tumor Metastasis through Necroptosis and Immune Response

To develop a potential theranostic metal agent to reverse the resistance of cancer cells to cisplatin and effectively inhibit tumor growth and metastasis, we proposed to design a cyclometalated iridium (Ir) complex based on the properties of the tumor environment (TME). To the end, we designed and synthesized a series of Ir(III) 2-hydroxy-1-naphthaldehyde thiosemicarbazone complexes by modifying the hydrogen atom(s) of the N-3 position of 2-hydroxy-1-naphthaldehyde thiosemicarbazone compounds and the structure of cyclometalated Ir(III) dimers and then investigated their structure-activity and structure-fluorescence relationships to obtain an Ir(III) complex (Ir5) with remarkable fluorescence and cytotoxicity to cancer cells. Ir5 not only possesses mitochondria-targeted properties but also overcomes cisplatin resistance and effectively inhibits tumor growth and metastasis in vivo. Besides, we confirmed the anticancer mechanisms of Ir5 acting on different components in the TME: directly killing liver cancer cells by inducing necroptosis and activating the necroptosis-related immune response.

Apoferritin-Cu(II) Nanoparticles Induce Oncosis in Multidrug-Resistant Colon Cancer Cells

Multidrug resistance (MDR) limits the application of clinical chemotherapeutic drugs. There is an urgent need to develop non-apoptosis-inducing agents that circumvent drug resistance. Herein, four therapeutic copper complexes encapsulated in natural nanocarrier apoferritin (AFt-Cu1-4) are reported. Although they are isomers, they exhibit significantly different organelle distributions and cell death mechanisms. AFt-Cu1 and AFt-Cu3 accumulate in the cytoplasm and induce autophagy, whereas AFt-Cu2 and AFt-Cu4 can quickly enter the nucleus and trigger oncosis. Excitedly, AFt-Cu2 and AFt-Cu4 show a strong tumor growth inhibition effect in mice models bearing multidrug-resistant colon xenograft via intravenous injection. To the best of the authors' knowledge, this is the first example of metal-based nucleus-targeted oncosis inducers overcoming multidrug resistance in vivo.

Novel 2-(5-Arylthiophen-2-yl)-benzoazole Cyclometalated Iridium(III) dppz Complexes Exhibit Selective Phototoxicity in Cancer Cells by Lysosomal Damage and Oncosis

A second-generation series of biscyclometalated 2-(5-aryl-thienyl)-benzimidazole and -benzothiazole Ir(III) dppz complexes [Ir(C^N)2(dppz)]+, Ir1-Ir4, were rationally designed and synthesized, where the aryl group attached to the thienyl ring was p-CF3C6H4 or p-Me2NC6H4. These new Ir(III) complexes were assessed as photosensitizers to explore the structure-activity correlations for their potential use in biocompatible anticancer photodynamic therapy. When irradiated with blue light, the complexes exhibited high selective potency across several cancer cell lines predisposed to photodynamic therapy; the benzothiazole derivatives (Ir1 and Ir2) were the best performers, Ir2 being also activatable with green or red light. Notably, when irradiated, the complexes induced leakage of lysosomal content into the cytoplasm of HeLa cancer cells and induced oncosis-like cell death. The capability of the new Ir complexes to photoinduce cell death in 3D HeLa spheroids has also been demonstrated. The investigated Ir complexes can also catalytically photo-oxidate NADH and photogenerate 1O2 and/or •OH in cell-free media.

The anticancer application of half-sandwich iridium(III) ferrocene-thiosemicarbazide Schiff base complexes

Ferrocenyl derivatives and organometallic iridium(III) complexes have been prospective substitutes for platinum-based anticancer drugs. Eight half-sandwich iridium(III) ferrocene-thiosemicarbazide (Fc-TSC) Schiff base anticancer complexes were prepared in this study. These complexes displayed a dimeric structure and exhibited a particular fluorescence due to the "enol" orientation of the TSC pro-ligand. An energy-dependent pathway of the uptake mechanism was ascertained, which ended in the lysosome and led to lysosome damage and apoptosis. Flow cytometry confirmed that the complexes could block the cell cycle (G1 phase) and improve the levels of intracellular reactive oxygen species, indicating an anticancer mechanism of oxidation. Then, a lysosomal-mitochondrial anticancer pathway was verified through western blotting. In vivo toxicity assays confirmed that these complexes showed better anti-migration ability and less toxicity in comparison to cisplatin. Thus, these complexes provide a new strategy for the design of non-platinum organometallic anticancer drugs.

Cell death classification: A new insight based on molecular mechanisms

Cells tend to disintegrate themselves or are forced to undergo such destructive processes in critical circumstances. This complex cellular function necessitates various mechanisms and molecular pathways in order to be executed. The very nature of cell death is essentially important and vital for maintaining homeostasis, thus any type of disturbing occurrence might lead to different sorts of diseases and dysfunctions. Cell death has various modalities and yet, every now and then, a new type of this elegant procedure gets to be discovered. The diversity of cell death compels the need for a universal organizing system in order to facilitate further studies, therapeutic strategies and the invention of new methods of research. Considering all that, we attempted to review most of the known cell death mechanisms and sort them all into one arranging system that operates under a simple but subtle decision-making (If \ Else) order as a sorting algorithm, in which it decides to place and sort an input data (a type of cell death) into its proper set, then a subset and finally a group of cell death. By proposing this algorithm, the authors hope it may solve the problems regarding newer and/or undiscovered types of cell death and facilitate research and therapeutic applications of cell death.

Mitochondria-targeted cyclometalated iridium (III) complexes: Dual induction of A549 cells apoptosis and autophagy

In this study, we synthesized 4 cyclometalated iridium complexes using N-(1,10-phenanthrolin-5-yl)picolinamide (PPA) as the main ligand, denoted as [Ir(ppy)2PPA]PF6 (ppy = 2-phenylpyridine, Ir1), [Ir(bzq)2PPA]PF6 (bzq = benzo[h]quinoline, Ir2), [Ir(dfppy)2PPA]PF6 (dfppy = 2-(3,5-difluorophenyl)pyridine, Ir3), and [Ir(thpy)2PPA]PF6 (thpy = 2-(thiophene-2-yl)pyridine, Ir4). Compared to cisplatin and oxaliplatin, all four complexes exhibited significant anti-tumor activity. Among them, Ir2 demonstrated higher cytotoxicity against A549 cells, with an IC50 value of 1.6 ± 0.2 μM. The experimental results indicated that Ir2 primarily localized in the mitochondria, inducing a large amount of reactive oxygen species (ROS) generation, that decreased in mitochondrial membrane potential (MMP), reduced ATP production, and further impaired mitochondrial function, leading to cytochrome c release. Additionally, Ir2 caused cell cycle arrest at the S phase and induced apoptosis through the AKT-mediated signaling pathway. Further investigations revealed that Ir2 could simultaneously induce both apoptosis and autophagy in A549 cells, with the latter acting as a non-protective mechanism that promoted cell death. More importantly, Ir2 exhibited low toxicity to both normal LO2 cells in vitro and zebrafish embryos in vivo. Consequently, these newly developed Ir(III) complexes show great potential in the development of novel and low-toxicity anticancer agents.

Inducing and monitoring mitochondrial pH changes with an iridium(III) complex via two-photon lifetime imaging

Real-time monitoring of mitochondrial dynamic changes plays a key role in the development of mitochondria-targeted anticancer theranostic agents. In this work, a pH-responsive and mitochondria-targeted cyclometalated iridium(III) complex MitoIr-NH has been explored as a novel anticancer agent. MitoIr-NH displayed pH-responsive phosphorescence intensity and lifetime, accumulated in mitochondria, showed higher antiproliferative activity and induced a series of mitochondria-related events. Moreover, MitoIr-NH could simultaneously induce mitophagy and quantitatively monitor mitochondrial pH changes through two-photon phosphorescence lifetime imaging microscopy (TPPLIM) in a real-time manner.

A Series of Planar Phosphorescent Cyclometalated Platinum(II) Complexes as New Anticancer Theranostic Agents That Induce Oncosis

Herein, four planar cyclometalated platinum(II) complexes with a main ligand of enlarged aromatic rings have been assessed as effective anticancer theranostic agents for the first time. With an increased number of aromatic rings in the N∧N ligand, 1a-1d exhibit increased lipophilicity and cytotoxicity selectivity. The intensity of the Pt-Pt interaction of each complex can be indicated by an enhanced near-infrared (NIR) emission in phosphate-buffered saline (PBS), their binding activity with biomolecules of bovine serum albumin (BSA) is accompanied by a vivid turn-on green emission, and the intensity gradually decreased from 1a to 1d, which is consistent with the docking of two complexes with BSA. Both "turn-on" NIR and green emission of 1d can be mainly observed in nuclei of living cell within 24 h, while two phosphorescence traces of 1b were recorded in lysosomes by confocal imaging. Moreover, 1d shows the highest efficiency in inducing oncosis of Hela cells, and the relative process was investigated.

Single neurons on microelectrode array chip: manipulation and analyses

Chips-based platforms intended for single-cell manipulation are considered powerful tools to analyze intercellular interactions and cellular functions. Although the conventional cell co-culture models could investigate cell communication to some extent, the role of a single cell requires further analysis. In this study, a precise intercellular interaction model was built using a microelectrode array [microelectrode array (MEA)]-based and dielectrophoresis-driven single-cell manipulation chip. The integrated platform enabled precise manipulation of single cells, which were either trapped on or transferred between electrodes. Each electrode was controlled independently to record the corresponding cellular electrophysiology. Multiple parameters were explored to investigate their effects on cell manipulation including the diameter and depth of microwells, the geometry of cells, and the voltage amplitude of the control signal. Under the optimized microenvironment, the chip was further evaluated using 293T and neural cells to investigate the influence of electric field on cells. An examination of the inappropriate use of electric fields on cells revealed the occurrence of oncosis. In the end of the study, electrophysiology of single neurons and network of neurons, both differentiated from human induced pluripotent stem cells (iPSC), was recorded and compared to demonstrate the functionality of the chip. The obtained preliminary results extended the nature growing model to the controllable level, satisfying the expectation of introducing more elaborated intercellular interaction models.

Exploring the Potential of Metal-Based Candidate Drugs as Modulators of the Cytoskeleton

During recent years, accumulating evidence suggested that metal-based candidate drugs are promising modulators of cytoskeletal and cytoskeleton-associated proteins. This was substantiated by the identification and validation of actin, vimentin and plectin as targets of distinct ruthenium(II)- and platinum(II)-based modulators. Despite this, structural information about molecular interaction is scarcely available. Here, we compile the scattered reports about metal-based candidate molecules that influence the cytoskeleton, its associated proteins and explore their potential to interfere in cancer-related processes, including proliferation, invasion and the epithelial-to-mesenchymal transition. Advances in this field depend crucially on determining binding sites and on gaining comprehensive insight into molecular drug-target interactions. These are key steps towards establishing yet elusive structure-activity relationships.

Rhenium(I) Tricarbonyl Complexes of 1,10-Phenanthroline Derivatives with Unexpectedly High Cytotoxicity

Eight rhenium(I) tricarbonyl aqua complexes with the general formula fac-[Re(CO)3(N,N'-bid)(H2O)][NO3] (1-8), where N,N'-bid is (2,6-dimethoxypyridyl)imidazo[4,5-f]1,10-phenanthroline (L1), (indole)imidazo[4,5-f]1,10-phenanthroline (L2), (5-methoxyindole)-imidazo[4,5-f]1,10-phenanthroline (L3), (biphenyl)imidazo[4,5-f]1,10-phenanthroline (L4), (fluorene)imidazo[4,5-f]1,10-phenanthroline (L5), (benzo[b]thiophene)imidazo[4,5-f]1,10-phenanthroline (L6), (5-bromothiazole)imidazo[4,5-f]1,10-phenanthroline (L7), and (4,5-dimethylthiophene)imidazo[4,5-f]1,10-phenanthroline (L8), were synthesized and characterized using 1H and 13C{1H} NMR, FT-IR, UV/Vis absorption spectroscopy, and ESI-mass spectrometry, and their purity was confirmed by elemental analysis. The stability of the complexes in aqueous buffer solution (pH 7.4) was confirmed by UV/Vis spectroscopy. The cytotoxicity of the complexes (1-8) was then evaluated on prostate cancer cells (PC3), showing a low nanomolar to low micromolar in vitro cytotoxicity. Worthy of note, three of the Re(I) tricarbonyl complexes showed very low (IC50 = 30-50 nM) cytotoxic activity against PC3 cells and up to 26-fold selectivity over normal human retinal pigment epithelial-1 (RPE-1) cells. The cytotoxicity of both complexes 3 and 6 was lowered under hypoxic conditions in PC3 cells. However, the compounds were still 10 times more active than cisplatin in these conditions. Additional biological experiments were then performed on the most selective complexes (complexes 3 and 6). Cell fractioning experiments followed by ICP-MS studies revealed that 3 and 6 accumulate mostly in the mitochondria and nucleus, respectively. Despite the respective mitochondrial and nuclear localization of 3 and 6, 3 did not trigger the apoptosis pathways for cell killing, whereas 6 can trigger apoptosis but not as a major pathway. Complex 3 induced a paraptosis pathway for cell killing while 6 did not induce any of our other tested pathways, namely, necrosis, paraptosis, and autophagy. Both complexes 3 and 6 were found to be involved in mitochondrial dysfunction and downregulated the ATP production of PC3 cells. To the best of our knowledge, this report presents some of the most cytotoxic Re(I) carbonyl complexes with exceptionally low nanomolar cytotoxic activity toward prostate cancer cells, demonstrating further the future viability of utilizing rhenium in the fight against cancer.

Dihydrotanshinone Triggers Porimin-Dependent Oncosis by ROS-Mediated Mitochondrial Dysfunction in Non-Small-Cell Lung Cancer

Lung cancer is one of the leading causes of cancer death. Non-small-cell lung cancer (NSCLC) accounts for the majority of lung cancer diagnoses. Dihydrotanshinone (DHT) is a compound extract from Salvia miltiorrhiza, which has favorable anti-inflammatory and anti-cancer activities. However, the role of DHT in NSCLC has not been fully studied. The anti-cancer drugs used for treating lung cancer often lead to apoptosis; however, the drug resistance of apoptosis restricts the effect of these drugs. Oncosis is a passive form of cell death that is different from apoptosis. It is characterized by cell swelling, and Porimin is a specific marker for oncosis. In this study, the role of DHT in mediating oncosis in A549 cells was investigated. In vitro, the MTS assay was used to detect cell activity after DHT treatment. Microscopy and electron microscopy were used to observe cell morphology changes. Western blotting was used to detect protein expression. Flow cytometry was used to detect intracellular reactive oxygen species (ROS) level, calcium ion (Ca2+) level, and cell mortality. The intracellular Lactic dehydrogenase (LDH) level was detected by an LDH detection kit after DHT treatment. The ATP level was detected using an ATP detection kit. In vivo, Lewis lung cancer (LLC) xenograft mice were used to evaluate the anti-tumor effect of DHT. Hematoxylin and eosin (HE) staining was used to detect the pathology of lung cancer tumors. The detection of Porimin in the tumor tissues of the mice after DHT administration was assessed by immunohistochemistry (IHC). The results of this study showed that DHT treatment changed the cell morphology; destroyed the mitochondrial structure; increased the expression of Porimin; increased the levels of LDH, ROS, and Ca2+; decreased the mitochondrial membrane potential and ATP level; and played an anti-tumor role in vitro by mediating oncosis in A549 cells. The in vivo studies showed that DHT could effectively inhibit tumor growth. The results of protein detection and IHC detection in the tumor tissues showed that the expression of Porimin was increased and that oncosis occurred in the tumor tissues of mice. DHT triggered Porimin-dependent oncosis by ROS-mediated mitochondrial dysfunction in NSCLC. The in vivo studies showed that DHT could inhibit tumor growth in LLC xenograft mice by triggering oncosis. This study indicates the potential for DHT to treat NSCLC.

Self-Immolative Photosensitizers for Self-Reported Cancer Phototheranostics

Photosensitizers to precise target and change fluorescence upon light illumination could accurately self-report where and when the photosensitizers work, enabling us to visualize the therapeutic process and precisely regulate treatment outcomes, which is the unremitting pursuit of precision and personalized medicine. Here, we report self-immolative photosensitizers by adopting a strategy of light-manipulated oxidative cleavage of C═C bonds that can generate a burst of reactive oxygen species, to cleave to release self-reported red-emitting products and trigger nonapoptotic cell oncosis. Strong electron-withdrawing groups are found to effectively suppress the C═C bond cleavage and phototoxicity via studying the structure-activity relationship, allowing us to elaborate NG1-NG5 that could temporarily inactivate the photosensitizer and quench the fluorescence by different glutathione (GSH)-responsive groups. Thereinto, NG2 with 2-cyano-4-nitrobenzene-1-sulfonyl group displays excellent GSH responsiveness than the other four. Surprisingly, NG2 shows better reactivity with GSH in weakly acidic condition, which inspires the application in weakly acidic tumor microenvironment where GSH elevates. To this end, we further synthesize NG-cRGD by anchoring integrin α_vβ₃ binding cyclic pentapeptide (cRGD) for tumor targeting. In A549 xenografted tumor mice, NG-cRGD successfully deprotects to restore near-infrared fluorescence because of elevated GSH in tumor site, which is subsequently cleaved upon light irradiation releasing red-emitting products to report photosensitizer working, while effectively ablating tumors via triggered oncosis. The advanced self-immolative organic photosensitizer may accelerate the development of self-reported phototheranostics in future precision oncology.

Multifunctional nanomedicines-enabled chemodynamic-synergized multimodal tumor therapy via Fenton and Fenton-like reactions

Chemodynamic therapy (CDT) is well-known for using the tumor microenvironment to activate the Fenton reaction or Fenton-like reaction to generate strong oxidative hydroxyl radicals for tumor-specific treatment. It is highly selective and safe, without depth limitation of tissue penetration, and shows its potential as a new green therapeutic method with great clinical application. However, the catalytic efficiency of reagents involved in the Fenton reaction is severely affected by the inherent microenvironmental limitations of tumors and the strict Fenton reaction-dependent conditions. With the increasing application of nanotechnology in the medical field, combined therapies based on different types of functional nanomaterials have opened up new avenues for the development of next-generation CDT-enhanced system. This review will comprehensively exemplify representative results of combined therapies of CDT with other antitumor therapies such as chemotherapy, phototherapy, sonodynamic therapy, radiation therapy, magnetic hyperthermia therapy, immunotherapy, starvation therapy, gas therapy, gene therapy, oncosis therapy, or a combination thereof for improving antitumor efficiency from hundreds of the latest literature, introduce strategies such as the ingenious design of nanomedicines and tumor microenvironment regulations to enhance the combination therapy, and further summarize the challenges and future perspective of CDT-based multimodal anticancer therapy.

Electroacupuncture ameliorates surgery-induced spatial memory deficits by promoting mitophagy in rats

Background

This study sought to explore the mechanism underlying the therapeutic effects of electroacupuncture (EA) on spatial memory deficits caused by surgery.

Methods

Hepatic apex resection was performed under propofol-based total intravenous anesthesia. Male Sprague-Dawley rats were subjected to EA treatment or EA + mitochondrial division inhibitor-1 (mdivi-1) treatment once a day for three consecutive days after surgery. The Morris water maze test was used to evaluate the spatial memory of the rats after surgery. Tissue from the hippocampus of each rat was frozen and used for transcriptomic and proteomic analyses to identify potential targets for EA treatment. Western blotting was used to confirm the protein expression levels. The levels of reactive oxygen species (ROS) and adenosine triphosphate (ATP) were detected using commercial kits. The rat mitochondria were then isolated, and the activity of mitochondrial complex V was assessed.

Results

EA attenuated surgery-induced spatial memory deficits on postoperative day 3, while these effects were reversed by treatment with the mdivi-1 (P<0.05). Ribonucleic acid (RNA)-sequencing revealed that EA upregulated multiple metabolic pathways and the phosphatidylinositol 3‑kinas/protein kinase B signaling pathway. The proteomic and western blotting results suggested that the EA treatment substantially downregulated coiled-coil-helix-coiled-coil-helix domain containing 3 (ChChd3) expression in the hippocampus. The EA treatment significantly increased the autophagy-related protein levels, including phosphatase and tensin homolog-induced kinase 1, Parkin, MAP1LC3 (LC3), and Beclin1, and inhibited the production of ROS and inflammatory cytokine interleukin-1β in the hippocampus (P<0.05).

Conclusions

These results suggest that EA ameliorates postoperative spatial memory deficits and protects hippocampus from oxidative stress and inflammation through enhanced autophagy in an animal model of perioperative neurocognitive disorders (PNDs).

N-Heterocyclic Carbene-Iridium Complexes as Photosensitizers for In Vitro Photodynamic Therapy to Trigger Non-Apoptotic Cell Death in Cancer Cells

A series of seven novel iridium complexes were synthetized and characterized as potential photosensitizers for photodynamic therapy (PDT) applications. Among them, four complexes were evaluated in vitro for their anti-proliferative activity with and without irradiation on a panel of five cancer cell lines, namely PC-3 (prostate cancer), T24 (bladder cancer), MCF7 (breast cancer), A549 (lung cancer) and HeLa (cervix cancer), and two non-cancerous cell models (NIH-3T3 fibroblasts and MC3T3 osteoblasts). After irradiation at 458 nm, all tested complexes showed a strong selectivity against cancer cells, with a selectivity index (SI) ranging from 8 to 34 compared with non-cancerous cells. The cytotoxic effect of all these complexes was found to be independent of the anti-apoptotic protein Bcl-xL. The compound exhibiting the best selectivity, complex 4a, was selected for further investigations. Complex 4a was mainly localized in the mitochondria. We found that the loss of cell viability and the decrease in ATP and GSH content induced by complex 4a were independent of both Bcl-xL and caspase activation, leading to a non-apoptotic cell death. By counteracting the intrinsic or acquired resistance to apoptosis associated with cancer, complex 4a could be an interesting therapeutic alternative to be studied in preclinical models.

Construction and validation of a novel algorithm based on oncosis-related lncRNAs comprising the immune landscape and prediction of colorectal cancer prognosis

Colorectal cancer (CRC) has high morbidity and mortality, particularly if diagnosed at an advanced stage. Although there have been several studies on CRC, few have investigated the relationship between oncosis and CRC. Thus, the purpose of the present study was to identify oncosis-related long noncoding RNAs (lncRNAs) and to establish a clinical prognostic model. Original data were acquired from The Cancer Genome Atlas database and PubMed. Differentially expressed oncosis-related lncRNAs (DEorlncRNAs) were identified and were subsequently formed into pairs. Next, a series of tests and analyses, including both univariate and multivariate analyses, as well as Lasso and Cox regression analyses, were performed to establish a receiver operating characteristic curve. A cut-off point was subsequently used to divide the samples into groups labelled as high- or low-risk. Thus, a model was established and evaluated in several dimensions. Six pairs of DEorlncRNAs associated with prognosis according to the algorithm were screened out and the CRC cases were divided into high- and low-risk groups. Significant differences between patients in the different risk groups were observed for several traits, including survival outcomes, clinical pathology characteristics, immune cell infiltration status and drug sensitivity. In addition, PCR and flow cytometry were performed to further verify the model. In summary, a new risk model algorithm based on six pairs of DEorlncRNAs in CRC, which does not require specific data regarding the level of gene expression, was established and validated. This algorithm may be used to predict patient prognosis, immune cell infiltration and drug sensitivity.

The role of autophagy in the treatment of colon cancer by chlorin e6 photodynamic therapy combined with oxaliplatin

BACKGROUND

Photodynamic therapy is a tumour treatment method. Its mechanism mainly induces apoptosis, autophagy, and other ways to cause cell death. Therefore, this study aims to evaluate the therapeutic effect of chlorine e6 photodynamic therapy (Ce6-PDT) combined with oxaliplatin (L-OHP) in colon cancer and to investigate the role of autophagy in L-OHP treatment and Ce6-PDT combined with L-OHP in colon cancer.

METHODS

CCK-8 assay, Scratch wound healing assay, and Western Blot (WB) were used to identify drug-resistant colon cancer cell line SW620/L-OHP. Annexin V/FITC assay, laser confocal double immunofluorescence staining method and WB were employed to investigate the apoptosis and autophagy changes in Ce6-PDT combined with L-OHP.

RESULTS

Drug resistance cells SW620/L-OHP were developed under the continuous multi-generation of L-OHP treatment, and the expression of ATP-binding cassette subfamily B member 1 (ABCB1) and ATG5 proteins were increased. The results of immunofluorescence showed that LC3B accumulated in SW620 cells and SW620/L-OHP cells under the treatment of L-OHP. The WB results indicated that LC3B and ATG5 protein expression was increasing in SW620 cells and SW620/L-OHP cells. Inhibition of L-OHP-induced autophagy reduces SW620 cells and SW620/L-OHP cells' viability while increasing apoptosis and the Pro Caspase-3 protein expression. The combination of Ce6-PDT and L-OHP decreased the cell viability, the cell migration ability, the Bcl-2 protein expression, and increased the apoptosis rate, Pro Caspase-3 protein expression in SW620 cells.

CONCLUSIONS

L-OHP can cause SW620 cells drug resistance. Autophagy plays a protective role in the L-OHP treatment of SW620 cells and SW620/L-OHP cells, and inhibition of autophagy can increase the efficacy of L-OHP. Ce6-PDT combined with L-OHP can further improve the tumor's therapeutic effect, and autophagy inhibition can improve the efficacy of combined therapy.

Potent anticancer activity of a novel iridium metallodrug via oncosis

Oncosis (from Greek ónkos, meaning "swelling") is a non-apoptotic cell death process related to energy depletion. In contrast to apoptosis, which is the main form of cell death induced by anticancer drugs, oncosis has been relatively less explored but holds potential to overcome drug resistance phenomena. In this study, we report a novel rationally designed mitochondria-targeted iridium(III) complex (OncoIr3) with advantageous properties as a bioimaging agent. OncoIr3 exhibited potent anticancer activity in vitro against cancer cells and displayed low toxicity to normal dividing cells. Flow cytometry and fluorescence-based assays confirmed an apoptosis-independent mechanism involving energy depletion, mitochondrial dysfunction and cellular swelling that matched with the oncotic process. Furthermore, a Caenorhabditis elegans tumoral model was developed to test this compound in vivo, which allowed us to prove a strong oncosis-derived antitumor activity in animals (with a 41% reduction of tumor area). Indeed, OncoIr3 was non-toxic to the nematodes and extended their mean lifespan by 18%. Altogether, these findings might shed new light on the development of anticancer metallodrugs with non-conventional modes of action such as oncosis, which could be of particular interest for the treatment of apoptosis-resistant cancers.

Phosphorescent Ir(III) Complexes for Biolabeling and Biosensing

Cyclometalated Ir(III) complexes exhibit strong phosphorescence emission with lifetime of submicroseconds to several microseconds at room temperature. Their synthetic versatility enables broad control of physical properties, such as charge and lipophilicity, as well as emission colors. These favorable properties have motivated the use of Ir(III) complexes in luminescent bioimaging applications. This review examines the recent progress in the development of phosphorescent biolabels and sensors based on Ir(III) complexes. It begins with a brief introduction about the basic principles of the syntheses and photophysical processes of cyclometalated Ir(III) complexes. Focus is placed on illustrating the broad imaging utility of Ir(III) complexes. Phosphorescent labels illuminating intracellular organelles, including mitochondria, lysosomes, and cell membranes, are summarized. Ir(III) complexes capable of visualization of tumor spheroids and parasites are also introduced. Facile chemical modification of the cyclometalating ligands endows the Ir(III) complexes with strong sensing ability. Sensors of temperature, pH, CO₂, metal ions, anions, biosulfur species, reactive oxygen species, peptides, and viscosity have recently been added to the molecular imaging tools. This diverse utility demonstrates the potential of phosphorescent Ir(III) complexes toward bioimaging applications.

Anticancer performance of Ir(III)-based anticancer agents in the treatment of cisplatin resistant cancer cells

The resistance to cisplatin of cancer cells have dramatically blocked its further application in the practical treatment. The generation of cisplatin resistance was a complicated physiological process, even several mechanisms have been reported. New metal-based agents with distinct anticancer mechanisms were still highly desired. In this concept, we have described Ir(III)-based anticancer agents and the underlying anticancer mechanisms, which could inhibit the antiproliferation of cisplatin resistant tumors. This work could benefit the society to develop more effective Ir(III)-based agents to combat cisplatin resistance.

Synthesis, physicochemical characterization and antiproliferative activity of phosphino Ru(II) and Ir(III) complexes

Herein, we present the synthesis of new complexes based on ruthenium(II) (Ru(η⁶-p-cymene)Cl₂PPh₂CH₂OH (RuPOH) and Ru(η⁶-p-cymene)Cl₂P(p-OCH₃Ph)₂CH₂OH (RuMPOH)) and iridium(III) (Ir(η⁵-Cp*)Cl₂P(p-OCH₃Ph)₂CH₂OH (IrMPOH) and Ir(η⁵-Cp*)Cl₂PPh₂CH₂OH (IrPOH)) containing phosphine ligands with/without methoxy motifs on phenyl rings (P(p-OCH₃Ph)₂CH₂OH (MPOH) and PPh₂CH₂OH (POH)). The complexes were characterized by mass spectrometry, NMR spectroscopy (1D: ¹H, ¹³C{¹H}, and ³¹P{¹H} and 2D: HMQC, HMBC, and COSY NMR) and elemental analysis. All the complexes were structurally identified by single-crystal X-ray diffraction analysis. The Ru(II) and Ir(III) complexes have a typical piano-stool geometry with an η⁶-coordinated arene (Ru^II complexes) or η⁵-coordinated (Ir^III compounds) and three additional sites of ligation occupied by two chloride ligands and the phosphine ligand. Oxidation of NADH to NAD⁺ with high efficiency was catalyzed by complexes containing P(p-OCH₃Ph)₂CH₂OH (IrMPOH and RuMPOH). The catalytic property might have important future applications in biological and medical fields like production of reactive oxygen species (ROS). Furthermore, the redox activity of the complexes was confirmed by cyclic voltamperometry. Biochemical assays demonstrated the ability of Ir(III) and Ru(II) complexes to induce significant cytotoxicity in various cancer cell lines. Furthermore, we found that RuPOH and RuMPOH selectively inhibit the proliferation of skin cancer cells (WM266-4; IC₅₀, after 24 h: av. 48.3 μM; after 72 h: av. 10.2 μM) while Ir(III) complexes were found to be moderate against prostate cancer cells (DU145).

Novel heterobimetallic Ir(III)-Re(I) complexes: design, synthesis and antitumor mechanism investigation

The reasonable design of binuclear or multinuclear metal complexes has demonstrated their potential advantages in the anticancer field. Herein, three heterobimetallic Ir(III)-Re(I) complexes, [Ir(C^N)₂LRe(CO)₃DIP](PF₆)₂ (C^N = 2-phenylpyridine (ppy, in IrRe-1), 2-(2-thienyl)pyridine (thpy, in IrRe-2) and 2-(2,4-difluorophenyl)pyridine (dfppy, in IrRe-3); L = pyridylimidazo[4,5-f][1,10]phenanthroline; DIP = 4,7-diphenyl-1,10-phenanthroline), were designed and synthesized. The heterobimetallic IrRe-1-3 complexes show pH-sensitive emission properties, which can be used for specific imaging of lysosomes. Additionally, IrRe-1-3 display higher cytotoxicity against tested tumor cell lines than the clinical chemotherapeutic drug cisplatin. Further mechanisms indicate that IrRe-1-3 can induce apoptosis and autophagy, increase intracellular reactive oxygen species (ROS), depolarize the mitochondrial membrane (MMP), block the cell cycle at the G0/G1 phase and inhibit cell migration. To the best of our knowledge, this is the first example of the synthesis of heterobimetallic Ir(III)-Re(I) complexes with superior anticancer activities and evaluation of their anticancer mechanisms.

Construction of an algorithm based on oncosis-related LncRNAs comprising the molecular subtypes and a risk assessment model in lung adenocarcinoma

Background

As an important non‐apoptotic cell death method, oncosis has been reported to be closely associated with tumors in recent years. However, few research reported the relationship between oncosis and lung cancer.

Methods

In this study, we established an oncosis‐based algorithm comprised of cluster grouping and a risk assessment model to predict the survival outcomes and related tumor immunity of patients with lung adenocarcinomas (LUAD). We selected 11 oncosis‐related lncRNAs associated with the prognosis (CARD8‐AS1, LINC00941, LINC01137, LINC01116, AC010980.2, LINC00324, AL365203.2, AL606489.1, AC004687.1, HLA‐DQB1‐AS1, and AL590226.1) to divide the LUAD patients into different clusters and different risk groups. Compared with patients in clsuter1, patients in cluster2 had a survival advantage and had a relatively more active tumor immunity. Subsequently, we constructed a risk assessment model to distinguish between patients into different risk groups, in which low‐risk patients tend to have a better prognosis. GO enrichment analysis revealed that the risk assessment model was closely related to immune activities. In addition, low‐risk patients tended to have a higher content of immune cells and stromal cells in tumor microenvironment, higher expression of PD‐1, CTLA‐4, HAVCR2, and were more sensitive to immune checkpoint inhibitors (ICIs), including PD‐1/CTLA‐4 inhibitors. The risk score had a significantly positive correlation with tumor mutation burden (TMB). The survival curve of the novel oncosis‐based algorithm suggested that low‐risk patients in cluster2 have the most obvious survival advantage.

Conclusion

The novel oncosis‐based algorithm investigated the prognosis and the related tumor immunity of patients with LUAD, which could provide theoretical support for customized individual treatment for LUAD patients.

Challenges and opportunities in the development of metal-based anticancer theranostic agents

Around 10 million fatalities were recorded worldwide in 2020 due to cancer and statistical projections estimate the number to increase by 60% in 2040. With such a substantial rise in the global cancer burden, the disease will continue to impose a huge socio-economic burden on society. Currently, the most widely used clinical treatment modality is cytotoxic chemotherapy using platinum drugs which is used to treat variety of cancers. Despite its clinical success, critical challenges like resistance, off-target side effects and cancer variability often reduce its overall therapeutic efficiency. These challenges require faster diagnosis, simultaneous therapy and a more personalized approach toward cancer management. To this end, small-molecule ‘theranostic’ agents have presented a viable solution combining diagnosis and therapy into a single platform. In this review, we present a summary of recent efforts in the design and optimization of metal-based small-molecule ‘theranostic’ anticancer agents. Importantly, we highlight the advantages of a theranostic candidate over the purely therapeutic or diagnostic agent in terms of evaluation of its biological properties.

Osmium(VI) nitride triggers mitochondria-induced oncosis and apoptosis

We report a new osmium(VI) nitrido complex bearing a nonplanar tetradentate ligand with potent anticancer activity. This complex causes mitochondrial damage, which induces liver cancer cell death via oncosis and apoptosis. This is the first osmium-based anticancer candidate that induces oncosis.

Pyroptosis-Mediated Periodontal Disease

Pyroptosis is a caspase-dependent process relevant to the understanding of beneficial host responses and medical conditions for which inflammation is central to the pathophysiology of the disease. Pyroptosis has been recently suggested as one of the pathways of exacerbated inflammation of periodontal tissues. Hence, this focused review aims to discuss pyroptosis as a pathological mechanism in the cause of periodontitis. The included articles presented similarities regarding methods, type of cells applied, and cell stimulation, as the outcomes also point to the same direction considering the cellular events. The collected data indicate that virulence factors present in the diseased periodontal tissues initiate the inflammasome route of tissue destruction with caspase activation, cleavage of gasdermin D, and secretion of interleukins IL-1β and IL-18. Consequently, removing periopathogens’ virulence factors that trigger pyroptosis is a potential strategy to combat periodontal disease and regain tissue homeostasis.

In Vitro and In Vivo of Triphenylamine-Appended Fluorescent Half-Sandwich Iridium(III) Thiosemicarbazones Antitumor Complexes

Half-sandwiched structure iridium(III) complexes appear to be an attractive organometallic antitumor agents in recent years. Here, four triphenylamine-modified fluorescent half-sandwich iridium(III) thiosemicarbazone (TSC) antitumor complexes were developed. Because of the "enol" configuration of the TSC ligands, these complexes formed a unique dimeric configuration. Aided by the appropriate fluorescence properties, studies found that complexes could enter tumor cells in an energy-dependent mode, accumulate in lysosomes, and result in the damage of lysosome integrity. Complexes could block the cell cycle, improve the levels of intrastitial reactive oxygen species, and lead to apoptosis, which followed an antitumor mechanism of oxidation. Compared with cisplatin, the antitumor potential in vivo and vitro confirmed that Ir4 could effectively inhibit tumor growth. Meanwhile, Ir4 could avoid detectable side effects in the experiments of safety evaluation. Above all, half-sandwich iridium(III) TSC complexes are expected to be an encouraging candidate for the treatment of malignant tumors.

A Continuous Add-On Probe Reveals the Nonlinear Enlargement of Mitochondria in Light-Activated Oncosis

Oncosis, depending on DNA damage and mitochondrial swelling, is an important approach for treating cancer and other diseases. However, little is known about the behavior of mitochondria during oncosis, due to the lack of probes for in situ visual illumination of the mitochondrial membrane and mtDNA. Herein, a mitochondrial lipid and mtDNA dual-labeled probe, MitoMN, and a continuous add-on assay, are designed to image the dynamic process of mitochondria in conditions that are unobservable with current mitochondrial probes. Meanwhile, the MitoMN can induce oncosis in a light-activated manner, which results in the enlargement of mitochondria and the death of cancer cells. Using structured illumination microscopy (SIM), MitoMN-stained mitochondria with a dual-color response reveals, for the first time, how swelled mitochondria interacts and fuses with each other for a nonlinear enlargement to accelerate oncosis into an irreversible stage. With this sign of irreversible oncosis revealed by MitoMN, oncosis can be segregated into three stages, including before oncosis, initial oncosis, and accelerated oncosis.

Autophagy-Dependent Apoptosis Induced by Apoferritin-Cu(II) Nanoparticles in Multidrug-Resistant Colon Cancer Cells

Chemotherapy continues to be the most commonly applied strategy for cancer. Despite the impressive clinical success obtained with several drugs, increasing numbers of (multi)drug-resistant tumors are reported. To overcome this shortcoming, novel drug candidates and delivery systems are urgently needed. Herein, a therapeutic copper polypyridine complex encapsulated in natural nanocarrier apoferritin is reported. The generated nanoparticles showed higher cytotoxicity toward various (drug-resistant) cancer cell lines than noncancerous cells. The study of the mechanism revealed that the compound triggers cell autophagy-dependent apoptosis. Promisingly, upon injection of the nanodrug conjugate into the bloodstream of a mouse model bearing a multidrug-resistant colon tumor, a strong tumor growth inhibition effect was observed. To date, this is the first study describing the encapsulation of a copper complex in apoferritin that acts by autophagy-dependent apoptosis.

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.

Cancer cell membrane camouflaged iridium complexes functionalized black-titanium nanoparticles for hierarchical-targeted synergistic NIR-II photothermal and sonodynamic therapy

The diagnosis and treatment of cancer is one of the biggest medical challenges of the century. Despite significant improvements, there remains an urgent need for novel anticancer procedures. Among the most promising approaches, increasing attention has been devoted towards photothermal and sonodynamic therapy in which sensitizers are activated upon light/ultrasound radiation to generate a cytotoxic effect. While these methods have undoubtedly shown a high therapeutic success, these techniques are intrinsically limited. Herein, the functionalization of black-titanium nanoparticle with iridium complexes and cancer cell membranes in a nanoplatform for hierarchical targeted synergistic photothermal and sonodynamic cancer imaging and therapy is proposed. The particles showed to generate efficiently heat upon irradiation and catalytically form reactive oxygen species upon ultrasound radiation. The nanoparticle formulation demonstrated to selectively localize in the mitochondria as well as to preferentially accumulate in cancerous over non-cancerous cells as well as in the tumor inside a mouse model, presenting a hierarchical targeting strategy. Upon synergistic irradiation at 1064 nm and ultrasound radiation, the nanoparticles were able to act as an imaging agent and identify the tumor site with high spatial resolution as well as act as a therapeutic agent and completely eradicate a tumor inside a mouse model.

Rational design of iridium-porphyrin conjugates for novel synergistic photodynamic and photothermal therapy anticancer agents

Near-infrared (NIR) emitters are important probes for biomedical applications. Nanoparticles (NPs) incorporating mono- and tetranuclear iridium(iii) complexes attached to a porphyrin core have been synthesized. They possess deep-red absorbance, long-wavelength excitation (635 nm) and NIR emission (720 nm). TD-DFT calculations demonstrate that the iridium-porphyrin conjugates herein combine the respective advantages of small organic molecules and transition metal complexes as photosensitizers (PSs): (i) the conjugates retain the long-wavelength excitation and NIR emission of porphyrin itself; (ii) the conjugates possess highly effective intersystem crossing (ISC) to obtain a considerably more long-lived triplet photoexcited state. These photoexcited states do not have the usual radiative behavior of phosphorescent Ir(iii) complexes, and they play a very important role in promoting the singlet oxygen (1O2) and heat generation required for photodynamic therapy (PDT) and photothermal therapy (PTT). The tetranuclear 4-Ir NPs exhibit high 1O2 generation ability, outstanding photothermal conversion efficiency (49.5%), good biocompatibility, low half-maximal inhibitory concentration (IC50) (0.057 μM), excellent photothermal imaging and synergistic PDT and PTT under 635 nm laser irradiation. To our knowledge this is the first example of iridium-porphyrin conjugates as PSs for photothermal imaging-guided synergistic PDT and PTT treatment in vivo.

BSA-encapsulated cyclometalated iridium complexes as nano-photosensitizers for photodynamic therapy of tumor cells

Photodynamic therapy is a promising treatment method. The development of suitable photosensitizers can improve therapeutic efficacy. Herein, we report three iridium complexes (Ir1, Ir2, and Ir3), and encapsulate them within bovine serum albumin (BSA) to form nano-photosensitizers (Ir1@BSA, Ir2@BSA, and Ir3@BSA) for photodynamic therapy (PDT) of tumor cells. In the structures of Ir(iii) complexes, we use the pyrazine heterocycle as part of the C^N ligands and explore the effect of different ligands on the ability to generate singlet oxygen (¹O₂) by changing the conjugation length of the ligand and increasing the coplanarity of the ligand. Besides, the fabricated nano-photosensitizers are beneficial to improve water dispersibility and increase cellular uptake ability. Through studying photophysical properties, ¹O₂ generation capacity, and cellular uptake performance, the results show that Ir1@BSA has the best photodynamic therapeutic effect on 4T1 tumor cells. This study provides an effective research basis for the further design of new nano-photosensitizers.

Three new iridium complexes were synthesized and fabricated with BSA to form nano-photosensitizers, which can catalyze oxygen to produce singlet oxygen to achieve photodynamic therapy of tumor cells.