Inhibition of SARS-CoV-2 replication by zinc gluconate in combination with hinokitiol.

The Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) pandemic is currently the major challenge to global public health. Two proteases, papain-like protease (PLpro) and the 3-chymotrypsin-like protease (3CLpro or Mpro), are indispensable for SARS-CoV-2 replication, making them attractive targets for antiviral therapy development. Here we screened a panel of essential metal ions using a proteolytic assay and identified that zinc gluconate, a widely-used zinc supplement, strongly inhibited the proteolytic activities of the two proteases in vitro. Biochemical and crystallographic data reveal that zinc gluconate exhibited the inhibitory function via binding to the protease catalytic site residues. We further show that treatment of zinc gluconate in combination with a small molecule ionophore hinokitiol, could lead to elevated intracellular Zn2+ level and thereby significantly impaired the two protease activities in cellulo. Particularly, this approach could also be applied to rescue SARS-CoV-2 infected mammalian cells, indicative of potential application to combat coronavirus infections. Our studies provide the direct experimental evidence that elevated intracellular zinc concentration directly inhibits SARS-CoV-2 replication and suggest the potential benefits to use the zinc supplements for coronavirus disease 2019 (COVID-19) treatment.

Recoding the Cancer Epigenome by Intervening in Metabolism and Iron Homeostasis with Mitochondria-Targeted Rhenium(I) Complexes.

The development and malignancy of cancer cells are closely related to the changes of the epigenome. In this work, a mitochondria-targeted rhenium(I) complex (DFX-Re3), integrating the clinical iron chelating agent deferasirox (DFX), has been designed. By relocating iron to the mitochondria and changing the key metabolic species related to epigenetic modifications, DFX-Re3 can elevate the methylation levels of histone, DNA, and RNA. As a consequence, DFX-Re3 affects the events related to apoptosis, RNA polymerases, and T-cell receptor signaling pathways. Finally, it is shown that DFX-Re3 induces immunogenic apoptotic cell death and exhibits potent antitumor activity in vivo. This study provides a new approach for the design of novel epigenetic drugs that can recode the cancer epigenome by intervening in mitochondrial metabolism and iron homeostasis.

Multifunctional low-temperature photothermal nanodrug with in vivo clearance, ROS-Scavenging and anti-inflammatory abilities.

Harsh photothermal temperatures, long-term body retention of nanoagents, elevated ROS and inflammation induction all threaten the normal tissues, thus hindering the translation of photothermal therapy (PTT) from bench to clinical practice. To resolve these problems, we have developed a disassembled theranostic nanodrug Qu-FeIIP based on the quercetin coordination. Herein, quercetin is not only the heat shock protein (Hsp 70) inhibitor but also the skeleton of Qu-FeIIP, realizing near-infrared light induced low-temperature PTT (45 °C) to ablate tumor completely without heat stress to normal tissues. Owing to the ROS scavenging ability of quercetin, Qu-FeIIP effectively reduces intracellular ROS and in vivo inflammatory factors (TNF-α, IL-6, IFN-γ) levels. Simultaneously, quercetin-Fe coordination is weakened when scavenging ROS, which triggers the Qu-FeIIP disassembling, resulting in effective clearance of nanoparticles from main organs 168 h post intravenous injection. Additionally, the photoacoustic and magnetic resonance dual-imaging capability of Qu-FeIIP offers excellent spatial resolution and imaging depth not only for precise tumor diagnosis but also for monitoring the nanodrug disassembling in vivo. Thus, Qu-FeIIP intrinsically integrates precise diagnosis, excellent low-temperature PTT efficacy, ROS elimination and anti-inflammatory action, dynamic disassembly and renal clearance ability into a single nanodrug, which is very promising for future clinical cancer treatment.

Folate receptor-targeted theranostic IrSx nanoparticles for multimodal imaging-guided combined chemo-photothermal therapy.

Nano-drug delivery systems with multi-modality imaging capacities are worth pursuing because they integrate diagnostic and therapeutic functions. Herein, we report the design, synthesis and evaluation of modified iridium sulfide (IrSx) nanoparticles (NPs) for cancer therapy in vitro and in vivo. This nanosystem was prepared by modifying IrSx with polyethylene glycol (PEG) conjugated to the targeting ligand folate (FA) for multimodal imaging-guided combined chemo-photothermal therapy. Upon PEG modification, the small IrSx NPs (about 4 nm) self-assembled into much larger (about 120 nm) IrSx-PEG-FA NPs, which exhibited high photostability, ideal photothermal effect, high drug loading and pH-/photothermal-responsive drug release properties. By using the model anticancer drug camptothecin (CPT), we demonstrated that CPT@IrSx-PEG-FA can effectively target FA-receptor-positive cancer cells in vitro and show efficient tumor accumulation in vivo. The combination of CPT@IrSx-PEG-FA treatment and irradiation with an 808 nm laser resulted in complete tumor elimination. Moreover, photothermal/photoacoustic (PA)/computed tomography (CT) imaging provided an effective means to monitor the therapeutic effects. Interestingly, the nanoparticles can be cleared, resulting in low systematic toxicity of CPT@IrSx-PEG-FA. Our work demonstrates that the as-prepared IrSx-PEG-FA NPs present a promising platform for the construction of multifunctional theranostic agents for cancer therapy.

Chitosan layered gold nanorods as synergistic therapeutics for photothermal ablation and gene silencing in triple-negative breast cancer.

Small interfering RNAs (siRNAs) are extensively studied due to their promising potential as therapeutic agents for a wide variety of diseases, including cancer. However, efficient delivery of siRNAs to target cells and tissues is problematic due to a lack of suitable delivery vehicles. In this work, we developed a layer-by-layer assembled chitosan-gold nanorods (Chit-Au NRs) siRNA delivery system to overcome biological barriers upon systemic injection. This platform was able to protect siRNAs form degradation upon exposure to ribonuclease (RNase) or serum. Confocal and intravital microscopy reveals that Chit-Au NRs/siRNAs are successfully delivered into target cells and tissue, and can efficiently escape from endosomal/lysosomal structures. Furthermore, Chit-Au NRs/siRNA were found to accumulate in high levels in tumor tissue. The delivery system was able to inhibit the oncogene expression (pyruvate kinase isozymeM2, PKM2) in MDA-MB-231 triple negative breast cancer cells, resulting in suppression of cell proliferation and migration. Moreover, the anticancer efficacy was further enhanced through NR-mediated photothermal ablation. In conclusion, the synergistic therapeutic properties of Chit-Au NRs/siRNA enable effective suppression of cancer growth. STATEMENT OF SIGNIFICANCE: Small interfering RNA (siRNA) therapy has promising therapeutic applications, since the expression of any protein can be suppressed. However the successful implementation of siRNA has been challenging, due to rapid degradation, poor intracellular uptake and insufficient endosomal escape. Here, we have developed a gold nanorod/chitosan-based delivery vehicle for siRNA therapy. This platform successfully overcomes the afore-mentioned challenges and can simultaneously be used for photothermal therapy, due to the optical properties of gold nanorods. We show that the anticancer activity is dramatically improved by combining thermal therapy with gene silencing. Furthermore, the Au NRs carrier shows high accumulation in tumor tissue and high transfection efficiency. This manuscript has been reviewed and approved by all co-authors. The research has not been disclosed or published and is not under consideration for publication elsewhere. We would appreciate if the manuscript could be reviewed and considered for publication in Acta BIOMATERIALIA.

Multifunctional gold nanorods for siRNA gene silencing and photothermal therapy.

Cancer is a complex disease that usually requires several treatment modalities. A multifunctional nanotherapeutic system is designed, incorporating small interfering RNA (siRNA) and gold nanorods (Au NRs) for photothermal therapy. Surface-engineered Au NRs with polyethylenimine are synthesized using a layer-by-layer assembly and siRNA is absorbed on the surface. The siRNA is efficiently delivered into breast cancer cells, resulting in subsequent gene silencing. Cells are then irradiated with near-infrared (NIR) light, causing heat-induced anticancer activity. The combination of gene silencing and photothermal therapy results in effective inhibition of cell proliferation.