Upconversion Luminescence-Boosted Escape of DNAzyme from Endosomes for Enhanced Gene-Silencing Efficacy

Despite the enormous potential of DNAzyme for gene therapy, its efficacy is hampered by the limited endosomal escape capability. Here, we develop a near-infrared (NIR) light-controlled DNAzyme delivery platform to achieve enhanced gene-silencing efficacy. The nanoplatform is composed of therapeutic DNAzyme, photosensitizers (PSs) and upconversion nanoparticles (UCNPs) that can convert NIR light to visible light. The system allows NIR light-activatable generation of cytotoxic reactive oxygen species due to the energy transfer from the UCNPs to PSs, which boosts the endosomal escape of DNAzyme for an improved gene-silencing efficacy. We demonstrate that the nanocomposites represent a promising platform to integrate DNAzyme-based gene therapy with NIR light-triggered photodynamic therapy for combinational tumor treatment. This work highlights a robust approach to combat the current limitations of DNAzyme delivery systems.

Facile synthesis of near-infrared responsive on-demand oxygen releasing nanoplatform for precise MRI-guided theranostics of hypoxia-induced tumor chemoresistance and metastasis in triple negative breast cancer

Background

Hypoxia is an important factor that contributes to chemoresistance and metastasis in triple negative breast cancer (TNBC), and alleviating hypoxia microenvironment can enhance the anti-tumor efficacy and also inhibit tumor invasion.

Methods

A near-infrared (NIR) responsive on-demand oxygen releasing nanoplatform (O₂-PPSiI) was successfully synthesized by a two-stage self-assembly process to overcome the hypoxia-induced tumor chemoresistance and metastasis. We embedded drug-loaded poly (lactic-co-glycolic acid) cores into an ultrathin silica shell attached with paramagnetic Gd-DTPA to develop a Magnetic Resonance Imaging (MRI)-guided NIR-responsive on-demand drug releasing nanosystem, where indocyanine green was used as a photothermal converter to trigger the oxygen and drug release under NIR irradiation.

Results

The near-infrared responsive on-demand oxygen releasing nanoplatform O₂-PPSiI was chemically synthesized in this study by a two-stage self-assembly process, which could deliver oxygen and release it under NIR irradiation to relieve hypoxia, improving the therapeutic effect of chemotherapy and suppressed tumor metastasis. This smart design achieves the following advantages: (i) the O₂ in this nanosystem can be precisely released by an NIR-responsive silica shell rupture; (ii) the dynamic biodistribution process of O₂-PPSiI was monitored in real-time and quantitatively analyzed via sensitive MR imaging of the tumor; (iii) O₂-PPSiI could alleviate tumor hypoxia by releasing O₂ within the tumor upon NIR laser excitation; (iv) The migration and invasion abilities of the TNBC tumor were weakened by inhibiting the process of EMT as a result of the synergistic therapy of NIR-triggered O₂-PPSiI.

Conclusions

Our work proposes a smart tactic guided by MRI and presents a valid approach for the reasonable design of NIR-responsive on-demand drug-releasing nanomedicine systems for precise theranostics in TNBC.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s12951-022-01294-z.

Tumor Microenvironment Responsive Single-Atom Nanozymes for Enhanced Antitumor Therapy

Single-atom nanozymes (SAzymes) with specific response to the unique tumor microenvironment (TME) feature providing 100% metal atoms utilization for high-efficient enzyme-catalyzed therapy and accurate template for the study of therapeutic mechanisms. In this review, we first introduce the various synthetic strategies of SAzymes, and the TME-responsive SAzymes activities. Next, the TME-responsive enhanced antitumor therapeutic approaches based on the enzymatic activities of SAzymes are summarized, and the corresponding therapy mechanisms are elaborated. Subsequently, a concise but concentrated summary, and the challenges and opportunities for the future design and engineering of SAzyme are outlined. As a newly-built discipline, SAzymes have vast space for development in enhanced antitumor therapy. This timely review provides guidance and constructive suggestions for the future of SAzymes.

A DNA Nanocomplex Containing Cascade DNAzymes and Promoter-Like Zn-Mn-Ferrite for Combined Gene/Chemo-dynamic Therapy

Sequential control of exogenous chemical events inside cells is a promising way to regulate cell functions and fate. Herein we report a DNA nanocomplex containing cascade DNAzymes and promoter-like Zn-Mn-Ferrite (ZMF), achieving combined gene/chemo-dynamic therapy. The promoter-like ZMF decomposed in response to intratumoral glutathione to release a sufficient quantity of metal ions, thus promoting cascade DNA/RNA cleavage and free radical generation. Two kinds of DNAzymes were designed for sequential cascade enzymatic reaction, in which metal ions functioned as cofactors. The primary DNAzyme self-cleaved the DNA chain with Zn²⁺ as cofactor, and produced the secondary DNAzyme; the secondary DNAzyme afterwards cleaved the EGR-1 mRNA, and thus downregulated the expression of target EGR-1 protein, achieving DNAzyme-based gene therapy. Meanwhile, the released Zn²⁺ , Mn²⁺ and Fe²⁺ induced Fenton/Fenton-like reactions, during which free radicals were catalytically generated and efficient chemo-dynamic therapy was achieved. In a breast cancer mouse model, the administration of DNA nanocomplex led to a significant therapeutic efficacy of tumor growth suppression.

Smart Nanozyme Platform with Activity-Correlated Ratiometric Molecular Imaging for Predicting Therapeutic Effects

Nanozymes with intrinsic enzyme-like characteristics have attracted enormous research interest in biological application. However, there is a lack of facile approach for evaluating the catalytic activity of nanozymes in living system. Herein, we develop a novel manganese-semiconducting polymer-based nanozyme (MSPN) with oxidase-like activity for reporting the catalytic activity of itself in acid-induced cancer therapy via ratiometric near-infrared fluorescence (NIRF)-photoacoustic (PA) molecular imaging. Notably, MSPN possess oxidase-like activity in tumor microenvironment, owing to the mixed-valent MnOx nanoparticles, which can effectively kill cancer cells. Because the semiconducting polymer (PFODBT) is conjugated with oxidase-responsive molecule (ORM), the catalytic activity of nanozyme can be correlated with the ratiometric signals of NIRF (FL₆₉₅ /FL₈₂₅ ) and PA (PA₆₈₀ /PA₇₈₀ ), which may provide new ideas for predicting anticancer efficacy of nanozymes in living system.

DNAzyme-Catalyzed Cellular Oxidative Stress Amplification for Pro-protein Activation in Living Cells

The conditional control of protein function in response to the physiological change of cells is of great interest for studying protein function in biological settings and developing protein therapeutics. We report herein that catalase (CAT) DNAzyme can potentiate the generation of reactive oxygen species (ROS) in living cells by knocking down catalase expression, which could further activate a reactive oxygen species (ROS)-responsive pro-protein, RNase A-NBC, in situ. Using an optimized lipid nanoparticle delivery system to simultaneously introduce CAT DNAzyme and RNase A-NBC into cells, we show that the pro-protein, RNase A-NBC, could be activated in a significantly enhanced manner to prohibit tumor cell growth in different types of cancer cells. We believe the methodology of regulating pro-protein activity using DNAzyme biocatalysis to differentiate intracellular environment could further be extended to other functional proteins, and even fundamental investigations in living systems to develop pro-protein therapeutics.

ZIF-Based Nanoparticles Combine X-Ray-Induced Nitrosative Stress with Autophagy Management for Hypoxic Prostate Cancer Therapy

Although reactive oxygen species (ROS)-mediated tumor treatments are predominant in clinical applications, ROS-induced protective autophagy promotes cell survival, especially in hypoxic tumors. Herein, X-ray triggered nitrite (NO₂ ^- ) is used for hypoxic prostate cancer therapy by inhibiting autophagy and inducing nitrosative stress based on an electrophilic zeolitic imidazole framework (ZIF-82-PVP). After internalization of pH-responsive ZIF-82-PVP nanoparticles, electrophilic ligands and Zn²⁺ are delivered into cancer cells. Electrophilic ligands can not only consume GSH under hypoxia but also capture low-energy electrons derived from X-rays to generate NO₂ ^- , which inhibits autophagy and further elevates lethal nitrosative stress levels. In addition, dissociated Zn²⁺ specifically limits the migration and invasion of prostate cancer cells through ion interference. In vitro and in vivo results indicate that ZIF-82-PVP nanoparticles under X-ray irradiation can effectively promote the apoptosis of hypoxic prostate cancer cells. Overall, this nitrosative stress-mediated tumor therapy strategy provides a novel approach targeting hypoxic tumors.

Self-Assembly of Copper-DNAzyme Nanohybrids for Dual-Catalytic Tumor Therapy

Despite the great efforts of using DNAzyme for gene therapy, its clinical success is limited by the lack of simple delivery systems and limited anticancer efficacy. Here, we develop a simple approach for the synthesis of hybrid nanostructures that exclusively consist of DNAzyme and Cu²⁺ with ultra-high loading capacity. The Cu-DNAzyme nanohybrids allow to effectively co-deliver DNAzyme and Cu²⁺ into cancer cells for combinational catalytic therapy. The released Cu²⁺ can be reduced to Cu⁺ by glutathione and then catalyze endogenous H₂ O₂ to form cytotoxic hydroxyl radicals for chemodynamic therapy (CDT), while the 10-23 DNAzyme enables the catalytic cleavage of VEGFR2 mRNA and activates gene silencing for gene therapy. We demonstrate that the system can efficiently accumulate in the tumor and exhibit amplified cascade antitumor effects with negligible systemic toxicity. Our work paves an extremely simple way to integrate DNAzyme with CDT for the dual-catalytic tumor treatment.

A Bimetallic Metal-Organic Framework Encapsulated with DNAzyme for Intracellular Drug Synthesis and Self-Sufficient Gene Therapy

Although chemotherapy is one of the most widely used cancer treatments, there are serious side effects, drug resistance, and secondary metastasis. To address these problems, herein we designed a bimetallic metal-organic framework (MOF) encapsulated with DNAzyme for co-triggered in situ cancer drug synthesis and DNAzyme-based gene therapy. Once in cancer cells, MOFs would disassemble and liberate copper ions, zinc ions, and DNAzyme under the acidic environment of lysosomes. Copper ions can catalyze the synthesis of the chemotherapeutic drug through copper-catalyzed azide-alkyne cycloaddition (CuAAC) reaction after being reduced to Cu^I ; zinc ions act as the cofactor to activate the cleavage activity of DNAzyme. The anticancer drug is synthesized intracellularly and can kill cancer cells on site to minimize side effects to normal organisms. The activated DNAzyme starts gene therapy to inhibit tumor proliferation and metastasis by targeting and cleaving oncogene substrates.