A dynamic cascade DNA nanocomplex to synergistically disrupt the pyroptosis checkpoint and relieve tumor hypoxia for efficient pyroptosis cancer therapy.

Pyroptosis has attracted widespread concerns in cancer therapy, while the therapeutic efficiency could be significantly restricted by using the crucial pyroptosis checkpoint of autophagy and tumor hypoxia. Herein, a DNA nanocomplex (DNFs@ZnMn), containing cascade DNAzymes, promoter-like ZnO2-Mn nanozymes and photosensitizers, was constructed in one pot through rolling circle amplification reactions to induce pyroptosis through disrupting autophagy. After targeting cancer cells with a high expression of H+ and glutathione, DNFs@ZnMn decomposed to expose DNAzymes and promoter-like ZnO2-Mn nanozymes. Then, sufficient metal ions and O2 were released to promote cascade DNA/RNA cleavage and relieving of tumor hypoxia. The released DNAzyme-1 self-cleaved long DNA strands with Zn2+ as the cofactor and simultaneously exposed DNAzyme-2 to cleave ATG-5 mRNA (with Mn2+ as the cofactor). This cascade DNAzyme-mediated gene regulation process induced downregulation of ATG-5 proteins to disrupt autophagy. Simultaneously, the released ZnO2 donated sufficient H2O2 to generate adequate O2 to relieve tumor hypoxia, obtaining highly cytotoxic 1O2 to trigger pyroptosis. By using dynamic cascade gene silencing to disrupt the pyroptosis checkpoint and synergistic relieving of hypoxia, this DNA nanocomplex significantly weakened cellular resistance to achieve efficient pyroptosis therapy both in vitro and in vivo.

Tumor-activated in situ synthesis of single-atom catalysts for O2-independent photodynamic therapy based on water-splitting.

Single-atom catalysts (SACs) have attracted interest in photodynamic therapy (PDT), while they are normally limited by the side effects on normal tissues and the interference from the Tumor Microenvironment (TME). Here we show a TME-activated in situ synthesis of SACs for efficient tumor-specific water-based PDT. Upon reduction by upregulated GSH in TME, C3N4-Mn SACs are obtained in TME with Mn atomically coordinated into the cavity of C3N4 nanosheets. This in situ synthesis overcomes toxicity from random distribution and catalyst release in healthy tissues. Based on the Ligand-to-Metal charge transfer (LMCT) process, C3N4-Mn SACs exhibit enhanced absorption in the red-light region. Thereby, a water-splitting process is induced by C3N4-Mn SACs under 660 nm irradiation, which initiates the O2-independent generation of highly toxic hydroxyl radical (·OH) for cancer-specific PDT. Subsequently, the ·OH-initiated lipid peroxidation process is demonstrated to devote effective cancer cell death. The in situ synthesized SACs facilitate the precise cancer-specific conversion of inert H2O to reactive ·OH, which facilitates efficient cancer therapy in female mice. This strategy achieves efficient and precise cancer therapy, not only avoiding the side effects on normal tissues but also overcoming tumor hypoxia.

Multienzyme-Like Polyoxometalate-Based Single-Atom Enzymes for Cancer-Specific Therapy Through Acid-Triggered Nontoxicity-to-Toxicity Transition.

Single-atom enzymes (SAzymes) exhibit great potential for chemodynamic therapy (CDT); while, general application is still challenged by their instability and unavoidable side effects during delivery. Herein, a manganese-based polyoxometalate single-atom enzyme (Mn-POM SAE) is first introduced into tumor-specific CDT, which exhibits tumor microenvironment (TME)-activated transition of nontoxicity-to-toxicity. Different from traditional POM materials, the aggregates of low-toxic Mn-POM SAE nanospheres are obtained at neutral conditions, facilitating efficient delivery and avoiding toxicity problems in normal tissues. Under acid TME conditions, these nanospheres are degraded into smaller units of toxic Mn(II)-PW11; thus, initiating cancer cell-specific therapy. The released active units of Mn(II)-PW11 exhibit excellent multienzyme-like activities (including peroxidase (POD)-like, oxidase (OXD)-like, catalase (CAT)-like, and glutathione peroxidase (Gpx)-like activities) for the synergistic cancer therapy due to the stabilized high valence Mn species (MnIII/MnIV). As demonstrated by both intracellular evaluations and in vivo experiments, ROS is generated to cause damage to lysosome membranes, further facilitating acidification and impaired autophagy to enhance cancer therapy. This study provides a detailed investigation on the acid-triggered releasing of active units and the electron transfer in multienzyme-mimic-like therapy, further enlarging the application of POMs from catalytical engineering into cancer therapy.

Synergistically remodulating H+/Ca2+ gradients to induce mitochondrial depolarization for enhanced synergistic cancer therapy.

The remodulation of H+/Ca2+ gradients in the mitochondria matrix could be effective to induce mitochondria depolarization for the enhancement of cancer therapy. However, it is still challenged by H+ homeostasis, insufficient Ca2+, uncoordinated regulations, and inefficient loading/delivery strategies. Herein, a supramolecular DNA nanocomplex (Ca@DNA-MF) was prepared to synergistically remodulate H+/Ca2+ gradients for mitochondrial depolarization. Upon targeted functionalization and TME-triggered delivery, multiple reagents were released in cancer cells for synergistic three-channel mitochondrial depolarization: the gene reagent of siMCT4 blocked the LA metabolism to induce mitochondrial acidification by downregulating monocarboxylate transporter 4 (MCT4); released Ca2+ disrupted Ca2+ homeostasis to facilitate Ca2+-based mitochondrial depolarization; specifically, TME-activated glutathione (GSH) depletion facilitated efficient generation of hydroxyl radicals (˙OH), further enhancing the mitochondrial depolarization. The remodulation not only triggered apoptosis but also led to ferroptosis to generate abundant ROS for efficient LPO-based apoptosis, providing a synergistic strategy for enhanced synergistic cancer therapy.

Ultrathin 2D Pd/Cu Single-Atom MOF Nanozyme to Synergistically Overcome Chemoresistance for Multienzyme Catalytic Cancer Therapy.

Single-atom nanozymes (SAzymes) have obtained increasing interest to mimic natural enzymes for efficient cancer therapy, while challenged by chemoresistance from cellular redox homeostasis and the interface of reductive species in tumor microenvironment (TME). Herein, a dual single-atomic ultrathin 2D metal organic framework (MOF) nanosheet of multienzyme (Pd/Cu SAzyme@Dzy) is prepared to synergistically overcome chemoresistance for multienzyme enhanced cancer catalytic therapy. The Pd SAzyme exhibits peroxidase (POD)-like catalytic activity for overcoming chemoresistance via disturbing cellular redox balance. This is further enhanced by cascade generation of more ∙OH via Cu+ -catalyzed POD-like reactions, initiated by in situ-reduction of Cu2+ into Cu+ upon GSH depletion. This process can also avoid the consumption of ∙OH by endogenous reductive GSH in TME, ensuring the adequate amount of ∙OH for highly efficient therapy. Besides, the DNAzyme is also delivered for gene therapy of silencing cancer-cell-targeting VEGFR2 protein to further enhance the therapy. Based on both experiments and theoretical calculations, the synergetic multienzyme-based cancer therapy is examined and the enhancement by the cascade tumor antichemoresistance is revealed.

Biomineralization of DNA Nanoframeworks for Intracellular Delivery, On-Demand Diagnosis, and Synergistic Cancer Treatments.

DNA nanoframeworks, with great biological information and controlled framework structures, exhibit great potentials in biological applications. Their applications are normally limited by unstable structures susceptible to hydrolysis, depurination, depyrimidination, oxidation, alkylation, or nuclease degradations. Herein, to ensure the mechanical and chemical stabilities of DNA nanoframeworks for intracellular applications, biomineralization of multifunctional DNA nanoframeworks with a tetrahedral skeleton is employed. Via silicification, the S-S bond is simultaneously introduced to obtain the silica-armored DNA nanoframeworks (Si-DNA nanoframeworks), mechanically and chemically stabilized for efficient intracellular deliveries. This successfully prevents degradations and leakages of reagents loaded on Si-DNA nanoframeworks, including biomolecular siRNA and small DOX drugs. Furthermore, the nucleic acid strands of the nanoframeworks are labeled with FAM and the quencher, facilitating miRNA detection upon "turn-on" signals from hybridizations. Therefore, the nanoframeworks collapse via double responses of the silica coating (silica acidic dissolution and S-S reduction by GSH) in cancer cells, realizing on-demand reagent release for miRNA detection and synergistic treatments (by siRNA and DOX). Demonstrated by both in vivo and in vitro experiments, the biomineralization has stabilized DNA nanomaterials for biological applications.