Boosting chemotherapy of bladder cancer cells by ferroptosis using intelligent magnetic targeting nanoparticles.

A versatile nano-delivery platform was reported to enhance the tumor suppression effect of chemotherapy by augmenting tumor cells' ferroptosis. The platform consists of pomegranate-like magnetic nanoparticles (rPAE@SPIONs) fabricated by encapsulating superparamagnetic iron oxide nanoparticles (SPIONs) within a reduced poly(ß-amino ester)s-PEG amphiphilic copolymer (rPAE). The resulting platform exhibits several functionalities. Firstly, it promotes the doxorubicin (DOX) release by leveraging the mild hyperthermia generated by NIR irradiation. Secondly, it triggers ferroptosis in tumor cells, inducing their demise. Thirdly, it induces polarization of macrophages towards an anti-tumor M1 phenotype, contributing to ferroptosis of tumor cells and enhanced tumor cell suppression. This study effectively capitalizes on the versatility of SPIONs and offers a simple yet powerful strategy for developing a new nanosized ferroptosis-inducing agent, ultimately improving the inhibition of bladder cancer cells.

The nanoformula of zoledronic acid and calcium carbonate targets osteoclasts and reverses osteoporosis.

Osteoporosis is known as an imbalance in bone catabolism and anabolism. Overactive bone resorption causes bone mass loss and increased incidence of fragility fractures. Antiresorptive drugs are widely used for osteoporosis treatment, and their inhibitory effects on osteoclasts (OCs) have been well established. However, due to the lack of selectivity, their off-target and side effects often bring suffering to patients. Herein, an OCs' microenvironment-responsive nanoplatform HA-MC/CaCO3/ZOL@PBAE-SA (HMCZP) is developed, consisting of succinic anhydride (SA)-modified poly(ß-amino ester) (PBAE) micelle, calcium carbonate shell, minocycline-modified hyaluronic acid (HA-MC) and zoledronic acid (ZOL). Results indicate that HMCZP, as compared with the first-line therapy, could more effectively inhibit the activity of mature OCs and significantly reverse the systemic bone mass loss in ovariectomized mice. In addition, the OCs-targeted capacity of HMCZP makes it therapeutically efficient at sites of severe bone mass loss and allows it to reduce the adverse effects of ZOL, such as acute phase reaction. High-throughput RNA sequencing (RNA-seq) reveals that HMCZP could down-regulate a critical osteoporotic target, tartrate-resistant acid phosphatase (TRAP), as well as other potential therapeutical targets for osteoporosis. These results suggest that an intelligent nanoplatform targeting OCs is a promising strategy for osteoporosis therapy.

Chemical transformation and cytotoxicity of iron oxide nanoparticles (IONPs) accumulated in mitochondria.

Iron oxide nanoparticles (IONPs) have been widely used as a nanoscale tool in biomedical research. However, it remains largely unknown how IONPs are transformed at a subcellular level to elicit distinct biological effects. In the present study, we prepared three different IONPs, including two IONPs targeting mitochondria (IONP-TPP) and lysosomes (IONP-APM), respectively, and a control with no specified target (IONP). By MTT assay and JC-1 staining, mitochondria-targeted IONP-TPP was found to produce significant cytotoxicity and severe mitochondrial membrane depolarization in MCF-7 cells. Furthermore, X-ray absorption spectroscopy (XAS) analysis revealed that IONP-TPP underwent remarkable edge defects and oxidation inside the cell. These findings suggest that IONPs are prone to the chemical transformation at mitochondria, and mitochondria are vulnerable to IONPs accumulation in the cell.

Precision Nanomedicines: Targeting Hot Mitochondria in Cancer Cells.

Mitochondrion is a multifunctional organelle in a cell, and it is one of the important targets of antitumor therapy. Conventional mitochondrial targeting strategies can hardly distinguish the mitochondria in cancer cells from those in normal cells, which might raise a concern about the biosafety. Recent studies suggest that a relatively high temperature of mitochondria exists in cancer cells. We named it tumor intrinsic mitochondrial overheating (TIMO). By taking advantage of the difference in mitochondrial temperatures between cancer cells and normal cells, therapeutic agents can be specifically delivered to the mitochondria in cancer cells. Here we will briefly overview the mitochondria-targeted delivery strategies. In addition, the recent discovery of hot mitochondria in cancer cells and the development of mitochondrial temperature-responsive delivery systems for antitumor therapy will be reviewed.

Mitochondrial temperature-responsive drug delivery reverses drug resistance in lung cancer.

Reversal of cancer drug resistance remains a critical challenge in chemotherapy. Mitochondria-targeted drug delivery has been suggested to mitigate drug resistance in cancer. To overcome the intrinsic limitations in conventional mitochondrial targeting strategies, we develop mitochondrial temperature-responsive drug delivery to reverse doxorubicin (DOX) resistance in lung cancer. Results demonstrate that the thermoresponsive nanocarrier can prevent DOX efflux and facilitate DOX accumulation and mitochondrial targeting in DOX-resistant tumors. As a consequence, thermoresponsive nanocarrier enhances the cytotoxicity of DOX and reverses the drug resistance in tumor-bearing mice. This work represents the first example of mitochondrial temperature-responsive drug delivery for reversing cancer drug resistance.

A Reduction Active Theranostic Nanoparticle for Enhanced Near-Infrared Imaging and Phototherapy by Reducing Glutathione Level in Cancer Cells.

Facile preparation of a tumoral-stimuli-activated theranostic nanoparticle with simple constituents remains a challenge for tumor theranostic nanosystems. Herein we design a simple reductionresponsive turn-on theranostic nanoparticle for achieving fluorescent imaging and phototherapy combination. The theranostic nanoparticle is prepared by a simple one-step dialysis method of reduction active amphiphilic hyperbranched poly(ß-amidoamines) and a near-infrared (NIR) dye indocyanine green (ICG). The fluorescence of ICG is quenched by the aggregation-caused quenching (ACQ) effect. The fluorescent intensity of free ICG at 816 nm was ∼40 times as high as that of particulate ICG. After reductive nanoparticles incubated with dithiothreitol (DTT), the size of the nanoparticles increased from 160 nm to 610 nm by Dynamic light scattering (DLS). As nanoparticles were internalized by cancer cells, the disulfide bonds would be cleaved by intracellular reduction agents like glutathione (GSH), leading to the release of entrapped ICG. The released ICG regained its fluorescence for self-monitoring the release and therapeutic effect of ICG by fluorescence spectra and the quantitative evaluation of NIR fluorescence intensity. Remarkably, nanoparticles can also reinforce antitumor efficacy through photodynamic therapy and GSH depletion property. This study provides new insights into designing turn-on theranostic systems.

The proximity of the G-quadruplex to hemin impacts the intrinsic DNAzyme activity in mitochondria.

The DNAzyme activity of G-quadruplex/hemin in mitochondria has not been characterized. Herein, we report an unexpected difference in the DNAzyme activity between in vitro assays and in mitochondria. Molecular dynamic simulations illustrate how the interaction of the G-quadruplex with hemin may modulate the DNAzyme activity. These results might facilitate a better understanding of the catalytic mechanism of the DNAzyme and help the rational design of stable and active DNAzymes suitable for intracellular catalysis.

D-arginine-loaded metal-organic frameworks nanoparticles sensitize osteosarcoma to radiotherapy.

Osteosarcoma is a common type of bone cancers with a high rate of pulmonary recurrence. High-dose radiation therapy is useful for the ablation of unresectable osteosarcoma. However, it may cause severe adverse effects. To address this problem, we developed D-arginine-loaded metal-organic frameworks (MOF) nanoparticles for improving the radiosensitivity of osteosarcoma. D-arginine, a metabolically inert enantiomer of L-arginine, could produce nitric oxide and down-regulate hypoxia-inducible factor-1alpha (HIF-1α) to alleviate tumor hypoxia. In addition, MOF could also generate free radicals to kill the tumor cells. Results demonstrate that D-arginine-loaded nanoparticles enhanced tumor ablation and prevented the lung metastasis in mice upon radiation therapy. Furthermore, the nanoparticles or radiation alone had relatively low toxicity in cells and mice. Therefore, D-arginine-loaded MOF nanoparticles are relatively safe and highly effective in sensitizing osteosarcoma to radiotherapy.

A surface convertible nanoplatform with enhanced mitochondrial targeting for tumor photothermal therapy.

Photothermal therapy emerges as a promising approach in antitumor treatment. A major challenge for conventional photothermal therapy is its unselective hyperthermia distribution within tumor tissues, which leads to detrimental effects on surrounding healthy tissues and compromised therapeutic effectiveness. In this study, a targeted photothermal delivery nanoplatform (P-D-CS-CNTs) was facilely fabricated by decoration of an acidity-labile polyethylene glycol (PEG) derivative onto chitosan nanoparticles encapsulating single-walled carbon nanotubes. P-D-CS-CNTs displayed a good stability in serum at normal physiological pH and convertibility of surface charges upon exposure to tumoral acidic pH, which was attributed to the acidity-triggered dePEGylation. The confocal laser scanning microscopic observations suggested that such surface-convertibility of nanoparticles facilitated tumor cell uptake, endo/lyososomal escape, and enhanced mitochondrial targeting. Furthermore, upon irradiation with an 808 nm laser, P-D-CS-CNTs could sabotage mitochondria with mild hyperthermia, which further induced the ROS burst from damaged mitochondria. The overdosed ROS ultimately resulted in mitochondrial damage and cell death. These findings indicate that the surface-convertible nanoplatform is promising for improved photothermal anticancer therapy.

Photo/thermo-responsive and size-switchable nanoparticles for chemo-photothermal therapy against orthotopic breast cancer.

Tumor penetration of nanocarriers is still an unresolved challenge for effective drug delivery. Herein, we described a size-switchable nanoplatform in response to an external near-infrared (NIR) laser for transcellular drug delivery. The nanoplatform was constructed with a poly(N-isopropylacrylamide) (PNIPAM)-based nanogel encapsulating chitosan-coated single-walled carbon nanotubes, followed by loading a chemotherapeutic drug, doxorubicin (DOX). In mice bearing orthotopic breast tumors, the photothermal effect from single-walled carbon nanotubes upon NIR irradiation potently inhibited tumor growth. The antitumor effect of the nanomedicine with NIR irradiation might be attributed to its capability of transcellular transport and tumor penetration in mice. In addition, the nanomedicine with NIR irradiation could elicit an antitumor response by increasing cytotoxic T cells and decreasing myeloid-derived suppressor cells. These results validated the application of photo/thermo-responsive nanomedicine in the orthotopic model of breast cancer.

Thermoresponsive drug delivery to mitochondria in vivo.

Mitochondrial targeting of drugs largely relies on delocalized lipophilic cations. Nevertheless, mitochondrial membrane potentials in cancer cells are inconstant, which could compromise stable mitochondrial targeting. Herein, we further validated a mitochondrial temperature-dependent drug delivery strategy in vivo. Thermoresponsive drug delivery to mitochondria may represent a promising strategy for cancer therapy.

AMPK mediates the neurotoxicity of iron oxide nanoparticles retained in mitochondria or lysosomes.

Environmental factors may play a critical role in the etiology and pathogenesis of Parkinson's disease (PD). However, the association of PD with specific chemical species remains largely unknown. Here we prepared three kinds of iron oxide nanoparticles and examined their cytotoxicity in a cellular model of PD. We found that lysosome-targeted nanoparticles showed significant cytotoxicity in SH-SY5Y cells. Inhibition of AMPK could aggravate the neurotoxicity of lysosome-targeted nanoparticles as well as mitochondrion-targeted nanoparticles. Alteration of mitochondrial membrane potentials was found to be in agreement with the neurotoxicity of iron nanoparticles. These results suggested an important role of AMPK in regulating iron nanoparticle-associated neurotoxicity.

Doxorubicin-Metal Coordinated Micellar Nanoparticles for Intracellular Codelivery and Chemo/Chemodynamic Therapy in Vitro.

Low cargo-loading capacity and inadequate stability have severely retarded the clinical translation of micellar nanomedicines. Herein, we present a nanosystem prepared by self-assembly of doxorubicin (DOX) and Fe2+ with drug-metal coordination interactions, followed by a surface decoration of multiarmed PEG-dipyridine. The micellar nanoparticles possessed high drug-loading capability and stability in physiological conditions. Results showed that nanoparticles facilitated the intracellular codelivery of Fe2+ and DOX. Moreover, intracellular overload of Fe2+ significantly enhanced the generation of ROS via the Fenton reaction. This strategy provides a facile method of preparing metal coordinated micellar nanoparticles for synergistic chemo/chemodynamic therapy.

Gold Nanoparticle-Based Probe for Analyzing Mitochondrial Temperature in Living Cells.

Validation of recent findings of hot mitochondria in cancer cells is critically needed, since a single fluorescent probe cannot rule out the possibility of varied cellular uptake efficiencies. Here we developed a ratiometric nanoprobe, named the mitochondria-targeted thermoresponsive-gold nanoparticle (MTT-AuNP), for analyzing mitochondrial temperatures. Results confirmed a relatively high mitochondrial temperature in murine bladder cancer MB49 cells. High temperatures in mitochondria might have far-reaching implications for developing mitochondria-targeted therapeutics.

Near-Infrared/pH Dual-Sensitive Nanocarriers for Enhanced Intracellular Delivery of Doxorubicin.

Herein, we designed near-infrared (NIR)/pH dual-sensitive nanocarriers and evaluated its application to intracellular drug delivery. The nanocarriers were prepared based on amphiphilic poly(ß-amino ester) (PBAE) containing o-nitrobenzyl moieties in the backbones and upconversion nanoparticles (UCNPs). UCNPs can convert NIR to UV that subsequently removes PEG segments from PBAE copolymers, which could enhance the protonation of PBAE in endo/lysosomes and facilitate the escape of the nanoparticles from lysosomes. In addition, we found the colocalization of the nanoparticles with mitochondria inside the cells, presumably resulting from high hydrophobicity and positive charges of the nanoparticles. The results showed that the nanocarriers with the aid of NIR could enhance the intracellular delivery of DOX, as compared with free DOX and NIR-free control. Furthermore, PBAE@UCNPs-DOX with NIR potently inhibited tumor growth in mice. Therefore, the intelligent micellar nanoparticles might provide a simple yet effective nanoplatform to achieve mitochondrion-targeting drug delivery.