Nano-medicine therapy reprogramming metabolic network of tumour microenvironment: new opportunity for cancer therapies

Metabolic heterogeneity is one of the characteristics of tumour cells. In order to adapt to the tumour microenvironment of hypoxia, acidity and nutritional deficiency, tumour cells have undergone extensive metabolic reprogramming. Metabolites involved in tumour cell metabolism are also very different from normal cells, such as a large number of lactate and adenosine. Metabolites play an important role in regulating the whole tumour microenvironment. Taking metabolites as the target, it aims to change the metabolic pattern of tumour cells again, destroy the energy balance it maintains, activate the immune system, and finally kill tumour cells. In this paper, the regulatory effects of metabolites such as lactate, glutamine, arginine, tryptophan, fatty acids and adenosine were reviewed, and the related targeting strategies of nano-medicines were summarised, and the future therapeutic strategies of nano-drugs were discussed. The abnormality of tumour metabolites caused by tumour metabolic remodelling not only changes the energy and material supply of tumour, but also participates in the regulation of tumour-related signal pathways, which plays an important role in the survival, proliferation, invasion and metastasis of tumour cells. Regulating the availability of local metabolites is a new aspect that affects tumour progress. (The graphical abstract is by Figdraw).

Nano-drug delivery system for the treatment of multidrug-resistant breast cancer: Current status and future perspectives

Breast cancer (BC) is one of the most frequently diagnosed cancers in women. Chemotherapy continues to be the treatment of choice for clinically combating it. Nevertheless, the chemotherapy process is frequently hindered by multidrug resistance, thereby impacting the effectiveness of the treatment. Multidrug resistance (MDR) refers to the phenomenon in which malignant tumour cells develop resistance to anticancer drugs after one single exposure. It can occur with a broad range of chemotherapeutic drugs with distinct chemical structures and mechanisms of action, and it is one of the major causes of treatment failure and disease relapse. Research has long been focused on overcoming MDR by using multiple drug combinations, but this approach is often associated with serious side effects. Therefore, there is a pressing need for in-depth research into the mechanisms of MDR, as well as the development of new drugs to reverse MDR and improve the efficacy of breast cancer chemotherapy. This article reviews the mechanisms of multidrug resistance and explores the application of nano-drug delivery system (NDDS) to overcome MDR in breast cancer. The aim is to offer a valuable reference for further research endeavours.

Optimization of boronic ester-based amphiphilic copolymers for ROS-responsive drug delivery

This study introduces boronic ester-based ROS-responsive amphiphilic copolymers for antioxidant drug delivery. Tuning the hydrophobic/hydrophilic balance optimized the size, curcumin encapsulation, ROS-triggered release, cellular uptake, and intracellular ROS scavenging. The lead P1b formulation self-assembled into stable 10 nm micelles enabling rapid ROS-triggered curcumin release and preferential cellular internalization. P1b eliminated over 90% of pathogenic intracellular ROS within 10 minutes, demonstrating a rapid antioxidant therapy.

Reversal of Chemoresistance via Staged Liberation of Chemodrug and siRNA in Hierarchical Response to ROS Gradient

P-glycoprotein (P-gp)-mediated multidrug resistance (MDR) often leads to the failure of antitumor chemotherapy, and codelivery of chemodrug with P-gp siRNA (siP-gp) represents a promising approach for treating chemoresistant tumors. To maximize the antitumor efficacy, it is desired that the chemodrug be latently released upon completion of siP-gp-mediated gene silencing, which however, largely remains an unmet demand. Herein, core-shell nanocomplexes (NCs) are developed to overcome MDR via staged liberation of siP-gp and chemodrug (doxorubicin, Dox) in hierarchical response to reactive oxygen species (ROS) concentration gradients. The NCs are constructed from mesoporous silica nanoparticles (MSNs) surface-decorated with cRGD-modified, PEGylated, ditellurium-crosslinked polyethylenimine (RPPT), wherein thioketal-linked dimeric doxorubicin (TK-Dox2) and photosensitizer are coencapsulated inside MSNs while siP-gp is embedded in the RPPT polymeric layer. RPPT with ultrahigh ROS-sensitivity can be efficiently degraded by the low-concentration ROS inside cancer cells to trigger siP-gp release. Upon siP-gp-mediated gene silencing and MDR reversal, light irradiation is performed to generate high-concentration, lethal amount of ROS, which cleaves thioketal with low ROS-sensitivity to liberate the monomeric Dox. Such a latent release profile greatly enhances Dox accumulation in Dox-resistant cancer cells (MCF-7/ADR) in vitro and in vivo, which cooperates with the generated ROS to efficiently eradicate MCF-7/ADR xenograft tumors.

Tumor-Targeted Oxaliplatin(IV) Prodrug Delivery Based on ROS-Regulated Cancer-Selective Glycan Labeling

Platinum-drug-based chemotherapy in clinics has achieved great success in clinical malignancy therapy. However, unpredictable off-target toxicity and the resulting severe side effects in the treatment are still unsolved problems. Although metabolic glycan labeling-mediated tumor-targeted therapy has been widely reported, less selective metabolic labeling in vivo limited its wide application. Herein, a novel probe of B-Ac3ManNAz that is regulated by reactive oxygen species in tumor cells is introduced to enhance the recognition and cytotoxicity of DBCO-modified oxaliplatin(IV) via bioorthogonal chemistry. B-Ac3ManNAz was synthesized from Ac4ManNAz by incorporation with 4-(hydroxymethyl) benzeneboronic acid pinacol ester (HBAPE) at the anomeric position, which is confirmed to be regulated by ROS and could robustly label glycans on the cell surface. Moreover, N3-treated tumor cells could enhance the tumor accumulation of DBCO-modified oxaliplatin(IV) via click chemistry meanwhile reduce the off-target distribution in normal tissue. Our strategy provides an effective metabolic precursor for tumor-specific labeling and targeted cancer therapies.

Multifunctional nanoparticles inhibit tumor and tumor-associated macrophages for triple-negative breast cancer therapy

HYPOTHESIS

Tumor-associated macrophages (TAM) are the mainstay of immunosuppressive cells in the tumor microenvironment, and elimination of M2-type macrophages (M2-TAM) is considered as a potential immunotherapy. However, the interaction of breast cancer cells with macrophages hinders the effectiveness of immunotherapy. In order to improve the efficacy of triple-negative breast cancer (TNBC) therapy, strategies that simultaneously target the elimination of M2-TAM and breast cancer cells may be able to achieve a better therapy.

EXPERIMENTS

LyP-SA/AgNP@Dox multifunctional nanoparticles were synthesized by electrostatic adsorption. They were characterized by particle size, potential and spectroscopy. And the efficacy of multifunctional nanoparticles was evaluated in 4 T1 cell lines and M2 macrophages, including their cell uptake intracellular reactive oxygen species (ROS) production and the therapeutic effect. Furthermore, based on the orthotopic xenotransplantation model of triple negative breast cancer, the biological distribution, fluorescence imaging, biosafety evaluation and combined efficacy evaluation of the nanoplatform were performed.

FINDINGS

We have successfully prepared LyP-SA/AgNP@Dox and characterized. Administering the nanosystem to 4 T1 tumor cells or M2 macrophages in culture induced accumulation of reactive oxygen species, destruction of mitochondria and apoptosis, and inhibited replication and transcription. Animal experiments demonstrated the nanoparticle had favorable targeting and antitumor activity. Our nanosystem may be useful for simultaneously inhibiting tumor and tumor-associated macrophages in breast cancer and, potentially, other malignancies.

ROS-Responsive Prodrug Micelle Co-Delivery System for Synergistic Antiatherosclerotic Therapy

Tanshinone IIA (TS-IIA) and salvianic acid A (SAA) are the main pharmacological active constituents of Danshen, which exhibit potent effects on atherosclerosis. A combination of TS-IIA and SAA might exert a synergistic antiatherosclerotic effect. However, the opposite solubility profiles of TS-IIA and SAA might lead to difficulty in achieving a synergistic combined effect of the two active components. Therefore, in this work, we fabricated a ROS-responsive prodrug micelle for the codelivery of TS-IIA and SAA (TS-IIA-PM) by self-assembling amphiphilic block copolymer PEG5000-SAA/PLA10000-APBA. The amphiphilic polymer was characterized by 1H NMR, FTIR, and alizarin red S competition tests. The ROS responsiveness of TS-IIA-PM was evidenced by time-course monitoring of particle size and morphology changes and drug release behavior in the presence of 1 mM H2O2. We found TS-IIA-PM was stable according to its critical micelle concentration and the unchanged particle sizes in 10% FBS for 7 days. The results of in vitro and in vivo tests revealed that TS-IIA-PM was safe and biocompatible. Furthermore, it was observed that TS-IIA and prodrug micelle could produce synergistic antiatherosclerotic effect based on the results of the antioxidant study, which was further confirmed by a series of pharmocodynamics studies, such as in vitro DiI-oxLDL uptake study, oil red O staining, cholesterol efflux study, inflammatory cytokine analysis, in vivo CD68 immunostaining, and lipid disposition staining studies. Collectively, TS-IIA-PM holds great potential for the safe and efficient codelivery of TS-IIA and SAA for synergistic antiatherosclerosis.

Progress on the pathological tissue microenvironment barrier-modulated nanomedicine

Imbalance in the tissue microenvironment is the main obstacle to drug delivery and distribution in the human body. Before penetrating the pathological tissue microenvironment to the target site, therapeutic agents are usually accompanied by three consumption steps: the first step is tissue physical barriers for prevention of their penetration, the second step is inactivation of them by biological molecules, and the third step is a cytoprotective mechanism for preventing them from functioning on specific subcellular organelles. However, recent studies in drug-hindering mainly focus on normal physiological rather than pathological microenvironment, and the repair of damaged physiological barriers is also rarely discussed. Actually, both the modulation of pathological barriers and the repair of damaged physiological barriers are essential in the disease treatment and the homeostasis maintenance. In this review, we present an overview describing the latest advances in the generality of these pathological barriers and barrier-modulated nanomedicine. Overall, this review holds considerable significance for guiding the design of nanomedicine to increase drug efficacy in the future.

Facile synthesis of poly(disulfide)s through one-step oxidation polymerization for redox-responsive drug delivery

Poly(disulfide)s-based systems with repetitive disulfide bonds in their backbones are emerging as promising tumor microenvironment responsive platforms for drug delivery. However, complicated synthesis and purification processes have restricted their further application. Herein, we developed redox-responsive poly(disulfide)s (PBDBM) by one-step oxidation polymerization of a commercially available monomer, 1,4-butanediol bis(thioglycolate) (BDBM). PBDBM can self-assemble with 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-poly(ethylene glycol)₃₄₀₀ (DSPE-PEG_3.4k) by the nanoprecipitation method and be formulated into PBDBM NPs (sub 100 nm). It can also be loaded with docetaxel (DTX), a first-line chemotherapy agent for breast cancer, to form DTX@PBDBM NPs with a loading capacity of 6.13%. DTX@PBDBM NPs with favorable size stability and redox-responsive capability exhibit superior antitumor activity in vitro. In addition, owing to the different glutathione (GSH) levels in normal and tumor cells, PBDBM NPs with disulfide bonds could synergistically increase intracellular ROS levels, further inducing apoptosis and cell cycle arrest in the G2/M phase. Moreover, in vivo studies revealed that PBDBM NPs could accumulate in tumors, suppress 4T1 tumor growth, and significantly attenuate the systemic toxicity of DTX. Thus, a novel redox-responsive poly(disulfide)s nanocarrier was successfully and facilely developed for cancer drug delivery and effective breast cancer therapy.

Nanocarriers overcoming biological barriers induced by multidrug resistance of chemotherapeutics in 2D and 3D cancer models

Multidrug resistance (MDR) is currently a big challenge in cancer therapy and limits its success in several patients. Tumors use the MDR mechanisms to colonize the host and reduce the efficacy of chemotherapeutics that are injected as single agents or combinations. MDR mechanisms are responsible for inactivation of drugs and formbiological barriers in cancer like the drug efflux pumps, aberrant extracellular matrix, hypoxic areas, altered cell death mechanisms, etc. Nanocarriers have some potential to overcome these barriers and improve the efficacy of chemotherapeutics. In fact, they are versatile and can deliver natural and synthetic biomolecules, as well as RNAi/DNAi, thus providing a controlled release of drugs and a synergistic effect in tumor tissues. Biocompatible and safe multifunctional biopolymers, with or without specific targeting molecules, modify the surface and interface properties of nanocarriers. These modifications affect the interaction of nanocarriers with cellular models as well as the selection of suitable models for in vitro experiments. MDR cancer cells, and particularly their 2D and 3D models, in combination with anatomical and physiological structures of tumor tissues, can boost the design and preparation of nanomedicines for anticancer therapy. 2D and 3D cancer cell cultures are suitable models to study the interaction, internalization, and efficacy of nanocarriers, the mechanisms of MDR in cancer cells and tissues, and they are used to tailor a personalized medicine and improve the efficacy of anticancer treatment in patients. The description of molecular mechanisms and physio-pathological pathways of these models further allow the design of nanomedicine that can efficiently overcome biological barriers involved in MDR and test the activity of nanocarriers in 2D and 3D models of MDR cancer cells.

Supramolecular Theranostic Nanomedicine for In Situ Self-Boosting Cancer Photochemotherapy

Although traditional nanomedicines have enhanced the therapeutic efficacy and improved the survival quality of cancer patients, random drug release and drug resistance are deep-rooted problems hindering their clinical application. A precise nanoplatform combing chemotherapy and photodynamic therapy (PDT) is developing as a new therapeutic strategy to overcome the above challenges. Herein, a novel supramolecular nanomedicine is ingeniously constructed for in situ self-boosting cancer photochemotherapy. Hydrophilic polyethylene glycol (PEG) chains or β-cyclodextrin (β-CD) hosts are first conjugated onto tetraphenyl porphyrin (TCPP) to improve the solubility of TCPP and decrease their π-π stacking interactions, guaranteeing a high-efficiency PDT. Then, two camptothecin (CPT) molecules are linked together via a reactive oxygen species (ROS)-responsive thioketal bond, which averts the premature burst release of CPT and realizes in situ drug release at the tumor site where PDT is performed, resulting in an enhanced chemotherapy. Benefiting from the collaboration of host-guest complexation between β-CD and CPT, multiple intermolecular hydrogen bonds of β-CD, π-π stacking interactions among CPT and TCPP as well as PEG shell protection, a prolonged blood circulation time, and a selective tumor accumulation are acquired, which facilitate the synergistic photochemotherapy and bring a pre-eminent antitumor response with a low systemic toxicity.

Multifunctional nanoparticle for cancer therapy

Cancer is a complex disease associated with a combination of abnormal physiological process and exhibiting dysfunctions in multiple systems. To provide effective treatment and diagnosis for cancer, current treatment strategies simultaneously focus on various tumor targets. Based on the rapid development of nanotechnology, nanocarriers have been shown to exhibit excellent potential for cancer therapy. Compared with nanoparticles with single functions, multifunctional nanoparticles are believed to be more aggressive and potent in the context of tumor targeting. However, the development of multifunctional nanoparticles is not simply an upgraded version of the original function, but involves a sophisticated system with a proper backbone, optimized modification sites, simple preparation method, and efficient function integration. Despite this, many well-designed multifunctional nanoparticles with promising therapeutic potential have emerged recently. Here, to give a detailed understanding and analyzation of the currently developed multifunctional nanoparticles, their platform structures with organic or inorganic backbones were systemically generalized. We emphasized on the functionalization and modification strategies, which provide additional functions to the nanoparticle. We also discussed the application combination strategies that were involved in the development of nanoformulations with functional crosstalk. This review thus provides an overview of the construction strategies and application advances of multifunctional nanoparticles.

Tumor Microenvironment-Based Stimuli-Responsive Nanoparticles for Controlled Release of Drugs in Cancer Therapy

With the development of nanomedicine technology, stimuli-responsive nanocarriers play an increasingly important role in antitumor therapy. Compared with the normal physiological environment, the tumor microenvironment (TME) possesses several unique properties, including acidity, high glutathione (GSH) concentration, hypoxia, over-expressed enzymes and excessive reactive oxygen species (ROS), which are closely related to the occurrence and development of tumors. However, on the other hand, these properties could also be harnessed for smart drug delivery systems to release drugs specifically in tumor tissues. Stimuli-responsive nanoparticles (srNPs) can maintain stability at physiological conditions, while they could be triggered rapidly to release drugs by specific stimuli to prolong blood circulation and enhance cancer cellular uptake, thus achieving excellent therapeutic performance and improved biosafety. This review focuses on the design of srNPs based on several stimuli in the TME for the delivery of antitumor drugs. In addition, the challenges and prospects for the development of srNPs are discussed, which can possibly inspire researchers to develop srNPs for clinical applications in the future.

Progress in the studies on the molecular mechanisms associated with multidrug resistance in cancers

Chemotherapy is one of the important methods to treat cancer, and the emergence of multidrug resistance (MDR) is one major cause for the failure of cancer chemotherapy. Almost all anti-tumor drugs develop drug resistance over a period of time of application in cancer patients, reducing their effects on killing cancer cells. Chemoresistance can lead to a rapid recurrence of cancers and ultimately patient death. MDR may be induced by multiple mechanisms, which are associated with a complex process of multiple genes, factors, pathways, and multiple steps, and today the MDR-associated mechanisms are largely unknown. In this paper, from the aspects of protein-protein interactions, alternative splicing (AS) in pre-mRNA, non-coding RNA (ncRNA) mediation, genome mutations, variance in cell functions, and influence from the tumor microenvironment, we summarize the molecular mechanisms associated with MDR in cancers. In the end, prospects for the exploration of antitumor drugs that can reverse MDR are briefly discussed from the angle of drug systems with improved targeting properties, biocompatibility, availability, and other advantages.