Hydrogen Evolution of a Unique DNAzyme Composed of Cobalt-Protoporphyrin IX and G-Quadruplex DNA.

Molecular hydrogen (H2 ) is a clean and renewable fuel that has garnered significant interest in the search for alternatives to fossil fuels. Here, we constructed an artificial DNAzyme composed of cobalt-protoporphyrin IX (CoPP) and G-quadruplex DNA, possessing a unique H2 Oint ligand between the CoPP and G-quartet planes. We show for the first time that CoPP-DNAzyme catalyzes photo-induced H2 production under anaerobic conditions with a turnover number (TON) of 1229 ± 51 over 12 h at pH 6.05 and 10 °C. Compared with free-CoPP, complexation with G-quadruplex DNA resulted in a 4.7-fold increase in H2 production activity. The TON of the CoPP-DNAzyme revealed an optimal acid-base equilibrium with a pKa value of 7.60 ± 0.05, apparently originating from the equilibrium between Co(III)-H- and Co(I) states. Our results demonstrate that the H2 Oint ligand can augment and modulate the intrinsic catalytic activity of H2 production catalysts. These systems pave the way to using DNAzymes for H2 evolution in the direct conversion of solar energy to H2 from water.

Mitochondrial nucleoid condensates drive peripheral fission through high membrane curvature.

Mitochondria are dynamic organelles that undergo fusion and fission events, in which the mitochondrial membrane and DNA (mtDNA) play critical roles. The spatiotemporal organization of mtDNA reflects and impacts mitochondrial dynamics. Herein, to study the detailed dynamics of mitochondrial membrane and mtDNA, we rationally develop a dual-color fluorescent probe, mtGLP, that could be used for simultaneously monitoring mitochondrial membrane and mtDNA dynamics via separate color outputs. By combining mtGLP with structured illumination microscopy to monitor mitochondrial dynamics, we discover the formation of nucleoid condensates in damaged mitochondria. We further reveal that nucleoid condensates promoted the peripheral fission of damaged mitochondria via asymmetric segregation. Through simulations, we find that the peripheral fission events occurred when the nucleoid condensates interacted with the highly curved membrane regions at the two ends of the mitochondria. Overall, we show that mitochondrial nucleoid condensates utilize peripheral fission to maintain mitochondrial homeostasis.

Evoking Ferroptosis by Synergistic Enhancement of a Cyclopentadienyl Iridium-Betulin Immune Agonist.

Ferroptosis is a form of programmed cell death driven by iron-dependent lipid peroxidation (LPO) with the potential for antitumor immunity activation. In this study, a nonferrous cyclopentadienyl metal-based ferroptosis inducer [Ir(Cp*)(Bet)Cl]Cl (Ir-Bet) was developed by a metal-ligand synergistic enhancement (MLSE) strategy involving the reaction of [Ir(Cp*)Cl]2 Cl2 with the natural product Betulin. The fusion of Betulin with iridium cyclopentadienyl (Ir-Cp*) species as Ir-Bet not only tremendously enhanced the antiproliferative activity toward cancer cells, but also activated ferritinophagy for iron homeostasis regulation by PI3K/Akt/mTOR cascade inhibition with a lower dosage of Betulin, and then evoked an immune response by nuclear factor kappa-B (NF-κB) activation of Ir-Cp* species. Further immunogenic cell death (ICD) occurred by remarkable ferroptosis through glutathione (GSH) depletion, glutathione peroxidase 4 (GPX4) deactivation and ferritinophagy. An in vivo vaccination experiment demonstrated desirable antitumor and immunogenic effects of Ir-Bet by increasing the ratio of cytotoxic T cells (CTLs)/regulatory T cells (Tregs).

Detection and tracking of cytoplasmic G-quadruplexes in live cells.

A TTPP probe was developed to distinguish G-quadruplexes (G4s) from other nucleic acid topologies through longer fluorescence lifetimes and higher quantum yields. In fluorescence lifetime imaging microscopy, TTPP enabled the visualization of cytoplasmic G4s in live cells, and showed the potential to detect cell apoptosis and ferroptosis by tracking cytoplasmic G4s.

Engineered Bacteria Labeled with Iridium(III) Photosensitizers for Enhanced Photodynamic Immunotherapy of Solid Tumors.

Despite metal-based photosensitizers showing great potential in photodynamic therapy for tumor treatment, the application of the photosensitizers is intrinsically limited by their poor cancer-targeting properties. Herein, we reported a metal-based photosensitizer-bacteria hybrid, Ir-HEcN, via covalent labeling of an iridium(III) photosensitizer to the surface of genetically engineered bacteria. Due to its intrinsic self-propelled motility and hypoxia tropism, Ir-HEcN selectively targets and penetrates deeply into tumor tissues. Importantly, Ir-HEcN is capable of inducing pyroptosis and immunogenic cell death of tumor cells under irradiation, thereby remarkably evoking anti-tumor innate and adaptive immune responses in vivo and leading to the regression of solid tumors via combinational photodynamic therapy and immunotherapy. To the best of our knowledge, Ir-HEcN is the first metal complex decorated bacteria for enhanced photodynamic immunotherapy.

A Golgi-Targeted Platinum Complex Plays a Dual Role in Autophagy Regulation for Highly Efficient Cancer Therapy.

Regulating autophagy to control the homeostatic recycling process of cancer cells is a promising anticancer strategy. Golgi apparatus is a substrate of autophagy but the Golgi-autophagy (Golgiphagy) mediated antitumor pathway is rarely reported. Herein, we have developed a novel Golgi-targeted platinum (II) complex Pt3, which is ca. 20 times more cytotoxic to lung carcinoma than cisplatin and can completely eliminate tumors after intratumoral administration in vivo. Its nano-encapsulated system for tail vein administration also features a good anti-tumor effect. Mechanism studies indicate that Pt3 induces substantial Golgi stress, indicated by the fragmentation of Golgi structure, down-regulation of Golgi proteins (GM130, GRASP65/55), loss of Golgi-dependent transport and glycosylation. This triggers Golgiphagy but blocks the subsequent fusion of autophagosomes with lysosomes, that is a dual role in autophagy regulation, resulting in loss of proteostasis and apoptotic cell death. As far as we know, Pt3 is the first Golgi-targeted Pt complex that can trigger Golgi stress-mediated dual-regulation of autophagic flux and autophagy-apoptosis crosstalk for highly efficient cancer therapy.

A Nanobody-Bioorthogonal Catalyst Conjugate Triggers Spatially Confined Prodrug Activation for Combinational Chemo-immunotherapy.

Checkpoint inhibitors have been used with chemotherapy to improve antitumor efficacy. However, overcoming the immunosuppressive effect of chemotherapeutics remains a challenge. We report a nanobody-catalyst conjugate Ru-PD-L1 by fusing a ruthenium catalyst to an anti-PD-L1 nanobody. After administration of Ru-PD-L1 and a doxorubicin (DOX) prodrug, Ru-PD-L1 disrupts the PD-L1/PD-1 interaction and catalyzes the uncaging of the DOX prodrug. The spatially confined release of DOX reduces its systemic toxicity and leads to immunogenic cell death (ICD). The induced ICD triggers antitumor immune responses, which are further amplified by PD-L1 blockade to elicit synergistic chemo-immunotherapy, substantially increasing the number of tumor-infiltrating T-cells by 49.7% compared with the controls, thereby exhibiting high antitumor activity and low cytotoxicity in murine models. The combinational treatment could inhibit the growth of mice tumors by 67.7% compared to the control group. This combinational approach circumvents the negative immunogenic effects of chemotherapeutics and provides a potential chemo-immunotherapy strategy for human cancer treatment.

Organic-Platinum Hybrids for Covalent Binding of G-Quadruplexes: Structural Basis and Application to Cancer Immunotherapy.

G-quadruplexes (G4s) have been revived as promising therapeutic targets with the development of immunotherapy, but the G4-mediated immune response remains unclear. We designed a novel class of G4-binding organic-platinum hybrids, L1 -cispt and L1 -transpt, with spatial matching for G4 binding and G4 DNA reactivity for binding site locking. The solution structure of L1 -transpt-MYT1L G4 demonstrated the effectiveness of the covalent binding and revealed the covalent binding-guided dynamic balance, accompanied by the destruction of the A5-T17 base pairs to achieve the covalent binding of the platinum unit to N7 of the G6 residue. Furthermore, L1 -cispt- and L1 -transpt-mediated genomic dysfunction could activate the retinoic acid-induced gene I (RIG-I) pathway and induce immunogenic cell death (ICD). The use of L1 -cispt/L1 -transpt-treated dying cells as therapeutic vaccines stimulated a robust immune response and effectively inhibited tumor growth in vivo. Our findings highlight the importance of the rational combination of specific spatial recognition and covalent locking in G4-trageting drug design and their potential in immunotherapy.

Aggregation-Induced Emission (AIE), Life and Health.

Light has profoundly impacted modern medicine and healthcare, with numerous luminescent agents and imaging techniques currently being used to assess health and treat diseases. As an emerging concept in luminescence, aggregation-induced emission (AIE) has shown great potential in biological applications due to its advantages in terms of brightness, biocompatibility, photostability, and positive correlation with concentration. This review provides a comprehensive summary of AIE luminogens applied in imaging of biological structure and dynamic physiological processes, disease diagnosis and treatment, and detection and monitoring of specific analytes, followed by representative works. Discussions on critical issues and perspectives on future directions are also included. This review aims to stimulate the interest of researchers from different fields, including chemistry, biology, materials science, medicine, etc., thus promoting the development of AIE in the fields of life and health.

Activation of the cGAS-STING pathway by a mitochondrial DNA-targeted emissive rhodium(iii) metallointercalator.

The cyclic GMP-AMP synthase (cGAS)-stimulator of interferon (STING) pathway is a key mediator of innate immunity involved in cancer development and treatment. The roles of mitochondrial DNA (mtDNA) in cancer immunotherapy have gradually emerged. Herein, we report a highly emissive rhodium(iii) complex (Rh-Mito) as the mtDNA intercalator. Rh-Mito can specifically bind to mtDNA to cause the cytoplasmic release of mtDNA fragments to activate the cGAS-STING pathway. Moreover, Rh-Mito activates the mitochondrial retrograde signaling by disturbing the key metabolites involved in epigenetic modifications, which alters the nuclear genome methylation landscape to influence the expression of genes related to immune signaling pathways. Finally, we demonstrate that ferritin-encapsulated Rh-Mito elicits potent anticancer activities and evokes intense immune responses in vivo by intravenous injection. Overall, we report for the first time that small molecules targeting mtDNA can activate the cGAS-STING pathway, which gives insights into the development of biomacromolecule-targeted immunotherapeutic agents.

Identification of Substrates of Secreted Bacterial Protease by APEX2-Based Proximity Labeling.

The interactions between bacterial virulence factors and host receptors play a critical role during bacterial infection. Therefore, the identification of interactions between host receptor and bacterial virulence factors can not only elucidate the molecular mechanisms of bacterial infection but also provide a framework for new therapeutic and prevention strategies. Herein, we report an APEX2-based live cell proximity labeling strategy in combination with high-resolution quantitative mass spectrometry to profile the substrates of Helicobacter pylori HtrA protease on the membrane of human stomach epithelial cells. This strategy can be further applied to identify other interactions between secreted bacterial virulence factors and host receptors on live cells.

Metals and inorganic molecules in regulating protein and nucleic acid phase separation.

The realization that liquid-liquid phase separation (LLPS) underlies the formation of membraneless compartments in cells has motivated efforts to modulate the condensation process of biomolecules. Increasing evidence shows that metals and inorganic molecules abundantly distributed in cells play important roles in the regulation of biomolecular condensation. Herein, we briefly reviewed the background of biomacromolecular phase separation and summarized the recent research progress on the roles of metals and inorganic molecules in regulating protein and nucleic acid phase separation in vitro and in cells.

Organometallic anti-tumor agents: targeting from biomolecules to dynamic bioprocesses.

The great clinical success of cisplatin and its derivatives has convinced people that metal complexes could play a more significant role in human cancer therapy. However, targeting and drug resistance are still two dominant problems that need to be urgently solved for metallodrugs' efficacy and clinical translation. As an important component of metal complexes, organometallics have been experiencing rapid development in recent years. Compared with platinum drugs, emerging anti-tumor organometallics targeting dynamic bioprocesses provide an effective strategy to overcome conventional problems. This review focuses on burgeoning anti-tumor strategies and provides up-to-date advances in anti-tumor organometallics development based on their action mechanisms. Specifically, important tumor-overexpressed proteins and nucleic acids as organometallics' anti-tumor targets are systematically presented, followed by organometallics that exert their anti-tumor activity by perturbing tumor intracellular energy/redox/metal/immune homeostasis. Finally, nine cell death pathways including apoptosis, paraptosis, autophagy, oncosis, necrosis, necroptosis, ferroptosis, pyroptosis, and immunogenic cell death (ICD) that can be induced by organometallics are reviewed, and their morphological and biochemical features are summarised. This review at the interface of chemistry, biology, and medicine aims to enlighten the rational development of organometallic anti-tumor agents.

Disruption of Zinc Homeostasis by a Novel Platinum(IV)-Terthiophene Complex for Antitumor Immunity.

Zinc homeostatic medicine is of great potential for cancer chemo-immunotherapy; however, there are few reports on antitumor compounds that can trigger Zn2+ -mediated immune responses. In this work, we developed a novel cyclometalated PtIV -terthiophene complex, Pt3, that not only induces DNA damage and cellular metabolism dysregulation, but also disrupts zinc homeostasis as indicated by the abnormal transcriptional level of zinc regulatory proteins, excess accumulation of Zn2+ in cytoplasm, and down-regulation of metallothioneins (MTs), which further caused redox imbalance. The simultaneous disruption of zinc and redox homeostasis in response to Pt3 treatment activated gasdermin-D mediated pyroptosis accompanied by cytoskeleton remodeling, thus releasing pro-inflammatory cytokines to promote dendritic cell (DC) maturation and T cell tumor-infiltration, eventually eliminating both primary and distant tumors in vivo. As far as we know, this is the first metal complex that can regulate zinc homeostasis to activate antitumor immunity.

A platinum-ruthenium hybrid prodrug with multi-enzymatic activities for chemo-catalytic therapy of hypoxic tumors.

Regulation of tumor hypoxia and redox homeostasis is a promising strategy for cancer therapy. Nanocatalytic medicine has played more and more important roles in this field because it can cleverly convert the efficiency and selectivity of catalysis into high therapeutic efficiency. Herein, we developed a platinum(iv)-ruthenium hybrid prodrug, named as Pt-Ru, for efficient chemo-catalytic synergistic therapy of hypoxic tumors. The ruthenium hybridization endowed the Pt(iv) prodrug with multi-enzyme catalytic activity, that is, mimicking catalase (CAT) to generate O2 in situ, mimicking peroxidase (POD) to produce reactive oxygen species, and mimicking glutathione peroxidase (GPx) to deplete GSH, thus effectively overcoming tumor hypoxia and cisplatin resistance. As a result, Pt-Ru treatment led to a superior anticancer efficacy to cisplatin both in vitro and in vivo. This work suggested redox homeostasis regulation as a tantalizing angle for developing the next generation of platinum drugs.

Pt(IV)-Deferasirox Prodrug Combats DNA Damage Repair by Regulating RNA N6-Methyladenosine Methylation.

DNA damage repair is considered to be an important mechanism of cisplatin resistance, and the roles of iron homeostasis in action mechanisms of cisplatin have not been studied yet. Herein, a Pt(IV) prodrug (DFX-Pt) integrating cisplatin and the clinical oral iron-chelating agent deferasirox (DFX) is found to be highly active toward cisplatin-insensitive triple-negative breast cancer cells both in vitro and in vivo. RNA-sequencing shows that DFX-Pt can downregulate genes related to the double-strand break (DSB) damage pathway significantly. DFX-Pt can reduce cellular free iron, regulate the expression of the RNA demethylase, and elevate the levels of RNA N6-methyladenosine (m6A), which degrades the DSB-related genes in an m6A-dependent manner. In all, we first reveal the roles of RNA modification in mechanisms of combating DNA damage repair and show that the combination of iron homeostasis intervention may bring new treatment regimens for cisplatin resistance.

Self-Amplifying Iridium(III) Photosensitizer for Ferroptosis-Mediated Immunotherapy Against Transferrin Receptor-Overexpressing Cancer.

Photoimmunotherapy is attractive for cancer treatment due to its spatial controllability and sustained responses. This work presents a ferrocene-containing Ir(III) photosensitizer (IrFc1) that can bind with transferrin and be transported into triple-negative breast cancer (TNBC) cells via a transferrin receptor-mediated pathway. When the ferrocene in IrFc1 is oxidized by reactive oxygen species, its capability to photosensitize both type I (electron transfer) and type II (energy transfer) pathways is activated through a self-amplifying process. Upon irradiation, IrFc1 induces the generation of lipid oxidation to cause ferroptosis in TNBC cells, which promotes immunogenic cell death (ICD) under both normoxia and hypoxia. In vivo, IrFc1 treatment elicits a CD8+ T-cell response, which activates ICD in TNBC resulting in enhanced anticancer immunity. In summary, this work reports a small molecule-based photosensitizer with enhanced cancer immunotherapeutic properties by eliciting ferroptosis through a self-amplifying process.

Ru(II)-modified TiO2 nanoparticles for hypoxia-adaptive photo-immunotherapy of oral squamous cell carcinoma.

The alternations in the hypoxic and immune microenvironment are closely related to the therapeutic effect and prognosis of oral squamous cell carcinoma (OSCC). Herein, a new nanocomposite, TiO2@Ru@siRNA is constructed from a ruthenium-based photosensitizer (Ru) modified-TiO2 nanoparticles (NPs) loaded with siRNA of hypoxia-inducible factor-1α (HIF-1α). Under visible light irradiation, TiO2@Ru@siRNA can elicit both Type I and Type II photodynamic effects, which causes lysosomal damage, HIF-1α gene silencing, and OSCC cell elimination efficiently. As a consequence of hypoxia relief and pyroptosis induction, TiO2@Ru@siRNA reshapes the immune microenvironment by downregulation of key immunosuppressive factors, upregulation of immune cytokines, and activation of CD4+ and CD8+ T lymphocytes. Furthermore, patient-derived xenograft (PDX) and rat oral experimental carcinogenesis models prove that TiO2@Ru@siRNA-mediated photodynamic therapy significantly inhibits the tumor growth and progression, and markedly enhances cancer immunity. In all, this study presents an effective hypoxia-adaptive photo-immunotherapeutic nanosystem with great potential for OSCC prevention and treatment.

Real-time tracking of ER turnover during ERLAD by a rhenium complex via lifetime imaging.

Endoplasmic reticulum (ER) degradation by autophagy (ER-phagy) is a recently revealed selective autophagy pathway that plays important roles in organelle turnover and protein degradation, but the biological functions of ER-phagy are largely unknown. Here, we present an ER-targeting Re(I) tricarbonyl complex (Re-ERLAD) that can accumulate in the ER, induce ER-to-lysosome-associated degradation (ERLAD) upon visible light irradiation, and label ER buds and track their morphological alterations during ER-phagy. The emission of Re-ERLAD is sensitive to viscosity, which is a key parameter reflecting the amount of unfolded protein in the ER. Quantitative detection using two-photon fluorescence lifetime imaging microscopy shows that ER viscosity initially increases and then decreases during ERLAD, which reveals that ERLAD is a pathway for alleviating ER stress caused by unfolded proteins. In conclusion, our work presents the first specific photoinducer and tracker of ERLAD, which can be used in studying the regulatory mechanism and function of this process.

Simultaneous Photoactivation of cGAS-STING Pathway and Pyroptosis by Platinum(II) Triphenylamine Complexes for Cancer Immunotherapy.

Activation of the cyclic GMP-AMP synthase-stimulator of the interferon gene (cGAS-STING) pathway is a potent anticancer immunotherapeutic strategy, and the induction of pyroptosis is a feasible way to stimulate the anticancer immune responses. Herein, two PtII complexes (Pt1 and Pt2) were designed as photoactivators of the cGAS-STING pathway. In response to light irradiation, Pt1 and Pt2 could damage mitochondrial/nuclear DNA and the nuclear envelope to activate the cGAS-STING pathway, and concurrently induce pyroptosis in cancer cells, which evoked an intense anticancer immune response in vitro and in vivo. Overall, we present the first photoactivator of the cGAS-STING pathway, which may provide an innovative design strategy for anticancer immunotherapy.