Self-assembly of a ruthenium-based cGAS-STING photoactivator for carrier-free cancer immunotherapy.

The cGAS (cyclic GMP-AMP synthase)-STING (stimulator of interferon genes) pathway promotes antitumor immune responses by sensing cytosolic DNA fragments leaked from nucleus and mitochondria. Herein, we designed a highly charged ruthenium photosensitizer (Ru1) with a ß-carboline alkaloid derivative as the ligand for photo-activating of the cGAS-STING pathway. Due to the formation of multiple non-covalent intermolecular interactions, Ru1 can self-assemble into carrier-free nanoparticles (NPs). By incorporating the triphenylphosphine substituents, Ru1 can target and photo-damage mitochondrial DNA (mtDNA) to cause the cytoplasmic DNA leakage to activate the cGAS-STING pathway. Finally, Ru1 NPs show potent antitumor effects and elicit intense immune responses in vivo. In conclusion, we report the first self-assembling mtDNA-targeted photosensitizer, which can effectively activate the cGAS-STING pathway, thus providing innovations for the design of new photo-immunotherapeutic agents.

Periodate-based molecular perovskites as promising energetic biocidal agents.

Epidemics caused by pathogens in recent years have created an urgent need for energetic biocidal agents with the capacity of detonation and releasing bactericides. Herein we present a new type of energetic biocidal agents based on a series of iodine-rich molecular perovskites, (H2dabco)M(IO4)3 (dabco = 1,4-diazabicyclo[2.2.2]octane, M = Na+/K+/Rb+/NH4 + for DAI-1/2/3/4) and (H2dabco)Na(H4IO6)3 (DAI-X1). These compounds possess a cubic perovskite structure, and notably have not only high iodine contents (49-54 wt%), but also high performance in detonation velocity (6.331-6.558 km s-1) and detonation pressure (30.69-30.88 GPa). In particular, DAI-4 has a very high iodine content of 54.0 wt% and simultaneously an exceptional detonation velocity up to 6.558 km s-1. As disclosed by laser scanning confocal microscopy observation and a standard micro-broth dilution method, the detonation products of DAI-4 exhibit a broad-spectrum bactericidal effect against bacteria (E. coli, S. aureus, and P. aeruginosa). The advantages of easy scale-up synthesis, low cost, high detonation performance, and high iodine contents enable these periodate-based molecular perovskites to be highly promising candidates for energetic biocidal agents. Electronic Supplementary Material: Supplementary material is available in the online version of this article at 10.1007/s40843-022-2257-6.

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.

A novel inhibitor of N 6-methyladenosine demethylase FTO induces mRNA methylation and shows anti-cancer activities.

N 6-methyladenosine (m6A) modification is critical for mRNA splicing, nuclear export, stability and translation. Fat mass and obesity-associated protein (FTO), the first identified m6A demethylase, is critical for cancer progression. Herein, we developed small-molecule inhibitors of FTO by virtual screening, structural optimization, and bioassay. As a result, two FTO inhibitors namely 18077 and 18097 were identified, which can selectively inhibit demethylase activity of FTO. Specifically, 18097 bound to the active site of FTO and then inhibited cell cycle process and migration of cancer cells. In addition, 18097 reprogrammed the epi-transcriptome of breast cancer cells, particularly for genes related to P53 pathway. 18097 increased the abundance of m6A modification of suppressor of cytokine signaling 1 (SOCS1) mRNA, which recruited IGF2BP1 to increase mRNA stability of SOCS1 and subsequently activated the P53 signaling pathway. Further, 18097 suppressed cellular lipogenesis via downregulation of peroxisome proliferator-activated receptor gamma (PPARγ), CCAAT/enhancer-binding protein alpha (C/EBPα), and C/EBPß. Animal studies confirmed that 18097 can significantly suppress in vivo growth and lung colonization of breast cancer cells. Collectively, we identified that FTO can work as a potential drug target and the small-molecule inhibitor 18097 can serve as a potential agent against breast cancer.

A Carbonic Anhydrase IX (CAIX)-Anchored Rhenium(I) Photosensitizer Evokes Pyroptosis for Enhanced Anti-Tumor Immunity.

An ideal cancer treatment should not only destroy primary tumors but also improve the immunogenicity of the tumor microenvironment to achieve a satisfactory anti-tumor immune effect. We designed a carbonic anhydrase IX (CAIX)-anchored rhenium(I) photosensitizer, named CA-Re, that not only performs type-I and type-II photodynamic therapy (PDT) with high efficiency under hypoxia (nanomolar-level phototoxicity), but also evokes gasdermin D (GSDMD) mediated pyroptotic cell death to effectively stimulate tumor immunogenicity. CA-Re could disrupt and self-report the loss of membrane integrity simultaneously. This promoted the maturation and antigen-presenting ability of dendritic cells (DCs), and fully activated T cells dependent adaptive immune response in vivo, eventually eliminating distant tumors at the same time as destroying primary tumors. To the best of our knowledge, CA-Re is the first metal complex-based pyroptosis inducer.

Ferroptosis-Enhanced Cancer Immunity by a Ferrocene-Appended Iridium(III) Diphosphine Complex.

Ferroptosis is a programmed cell death pathway discovered in recent years, and ferroptosis-inducing agents have great potential as new antitumor candidates. Here, we report a IrIII complex (Ir1) containing a ferrocene-modified diphosphine ligand that localizes in lysosomes. Under the acidic environments of lysosomes, Ir1 can effectively catalyze Fenton-like reaction, produce hydroxyl radicals, induce lipid peroxidation, down-regulate glutathione peroxidase 4, and result in ferroptosis. RNA sequencing analysis shows that Ir1 can significantly affect pathways related to ferroptosis and cancer immunity. Accordingly, Ir1 can induce immunogenic cells death and suppress tumor growth in vitro, regulate T cell activity and immune microenvironments in vivo. In conclusion, we show the potential of small molecules with ferroptosis-inducing capabilities for effective cancer immunotherapy.

Regulating Tumor N6 -Methyladenosine Methylation Landscape using Hypoxia-Modulating OsSx Nanoparticles.

The epigenetic dysregulation and hypoxia are two important factors that drive tumor malignancy, and N6 -methyladenosine (m6 A) in mRNA is involved in the regulation of gene expression. Herein, a nanocatalyst OsSx -PEG (PEG = poly(ethylene glycol)) nanoparticles (NPs) as O2 modulator is developed to improve tumor hypoxia. OsSx -PEG NPs can significantly downregulate genes involved in hypoxia pathway. Interestingly, OsSx -PEG NPs elevate RNA m6 A methylation levels to cause the m6 A-dependent mRNA degradation of the hypoxia-related genes. Moreover, OsSx -PEG NPs can regulate the expression of RNA m6 A methyltransferases and demethylases. Finally, DOX@OsSx -PEG (DOX = doxorubicin; utilized as a model drug) NPs modulate tumor hypoxia and regulate mRNA m6 A methylation of hypoxia-related genes in vivo. As the first report about relationship between catalytic nanomaterials and RNA modifications, the research opens a new avenue for unveiling the underlying action mechanisms of hypoxia-modulating nanomaterials and shows potential of regulating RNA modification to overcome chemoresistance.

HDAC8 promotes the dissemination of breast cancer cells via AKT/GSK-3ß/Snail signals.

The mechanistic action of histone deacetylase 8 (HDAC8) in cancer motility, including epithelial-mesenchymal transition (EMT), remains largely undefined. We found that the expression of HDAC8 was upregulated in breast cancer (BC) cells and tissues as compared to the controls. Further, BC tissues had the highest values of HDAC8 expression among 31 kinds of cancers. Cellular study indicated that HDAC8 can positively regulate the dissemination and EMT of BC cells. It increased the protein stability of Snail, an important regulator of EMT, by phosphorylation of its motif 2 in serine-rich regions. There are 21 factors that have been reported to regulate the protein stability of Snail. Among them, HDAC8 can decrease the expression of GSK-3ß through increasing its Ser9-phosphorylation. Mass spectrum analysis indicated that HDAC8 interact with AKT1 to decrease its acetylation while increase its phosphorylation, which further increased Ser9-phosphorylation of GSK-3ß. The C-terminal of AKT1 was responsible for the interaction between HDAC8 and AKT1. Further, Lys426 was the key residue for HDAC8-regulated deacetylation of AKT1. Moreover, HDAC8/Snail axis acted as adverse prognosis factors for in vivo progression and overall survival (OS) rate of BC patients. Collectively, we found that HDAC8 can trigger the dissemination of BC cells via AKT/GSK-3ß/Snail signals, which imposed that inhibition of HDAC8 is a potential approach for BC treatment.

Targeted mRNA demethylation using an engineered dCas13b-ALKBH5 fusion protein.

Studies on biological functions of N6-methyladenosine (m6A) modification in mRNA have drawn significant attention in recent years. Here we describe the construction and characterization of a CRISPR-Cas13b-based tool for targeted demethylation of specific mRNA. A fusion protein, named dm6ACRISPR, was created by linking a catalytically inactive Type VI-B Cas13 enzyme from Prevotella sp. P5-125 (dPspCas13b) to m6A demethylase AlkB homolog 5 (ALKBH5). dm6ACRISPR specifically demethylates m6A of targeted mRNA such as cytochrome b5 form A (CYB5A) to increase its mRNA stability. It can also demethylate ß-catenin-encoding CTNNB1 mRNA that contains multiple m6A sites to trigger its translation. In addition, the dm6ACRISPR system incurs efficient demethylation of targeted epitranscriptome transcripts with limited off-target effects. Targeted demethylation of transcripts coding for oncoproteins such as epidermal growth factor receptor (EGFR) and MYC can suppress proliferation of cancer cells. Together, we provide a programmable and in vivo manipulation tool to study mRNA modification of specific genes and their related biological functions.

N6-methyladenosine induced miR-143-3p promotes the brain metastasis of lung cancer via regulation of VASH1.

BACKGROUND: Brain metastasis (BM) is one of the principal causes of mortality for lung cancer patients. While the molecular events that govern BM of lung cancer remain frustrating cloudy. METHODS: The miRNA expression profiles are checked in the paired human BM and primary lung cancer tissues. The effect of miR-143-3p on BM of lung cancer cells and its related mechanisms are investigated. RESULTS: miR-143-3p is upregulated in the paired BM tissues as compared with that in primary cancer tissues. It can increase the invasion capability of in vitro blood brain barrier (BBB) model and angiogenesis of lung cancer by targeting the three binding sites of 3'UTR of vasohibin-1 (VASH1) to inhibit its expression. Mechanistically, VASH1 can increase the ubiquitylation of VEGFA to trigger the proteasome mediated degradation, further, it can endow the tubulin depolymerization through detyrosination to increase the cell motility. m6A methyltransferase Mettl3 can increase the splicing of precursor miR-143-3p to facilitate its biogenesis. Moreover, miR-143-3p/VASH1 axis acts as adverse prognosis factors for in vivo progression and overall survival (OS) rate of lung cancer. CONCLUSIONS: Our work implicates a causal role of the miR-143-3p/VASH1 axis in BM of lung cancers and suggests their critical roles in lung cancer pathogenesis.

Histone deacetylase 8 triggers the migration of triple negative breast cancer cells via regulation of YAP signals.

Triple-negative breast cancer (TNBC) shows highly aggressive clinical behaviors and poor prognosis compared to other breast cancer subtypes. Histone deacetylases (HDACs) can regulate the progression of various cancers, but the role of HDAC8 in TNBC remains unexplored. Here, we found that HDAC8 enhanced the in vitro migration abilities of breast cancer cells. Targeted inhibition of HDAC8 via si-HDAC8 and its selective inhibitor PCI34051 could suppress the migration of cells. In TNBC cells, HDAC8 stabilized the expression and increased the nuclear localization of YAP, a major downstream effector of Hippo pathway. While silencing YAP could attenuate HDAC8 triggered migration of TNBC cells. Mechanistically, HDAC8 suppressed the phosphorylation of YAPSer127, which was related to its cytoplasmic sequestration degradation. Our data revealed that HDAC8 could trigger the migration of TNBC cells via regulation of Hippo-YAP signals, suggesting that HDAC8 might be a potential target for TNBC therapy.