Cancer therapeutic strategies based on metal ions

Metal-modulated T cell antitumor immunity and emerging metalloimmunotherapy

In recent years, increasing evidence has shown that metals play important roles in both innate and adaptive immunity. An emerging concept of metalloimmunotherapy has been proposed, which may accelerate the development of immunotherapy for cancers. Here, we discuss how metals affect T cell function through different signaling pathways. Metals impact the fate of T cells, including their activation, proliferation, cytotoxicity, and differentiation. Most importantly, metals also participate in mitochondrial operation by regulating energy production and reactive oxygen species homeostasis in T cells. We also identified the metal-based mutual effects between tumor cells and T cells in the tumor microenvironment. Overall, the antitumor effect of T cells can be improved by targeting metal metabolism and metalloimmunotherapy, which will be a step forward in the treatment of cancers.

Metal ion crosslinked polysaccharide hydrogels: A review on their potential for therapeutic delivery and tissue engineering

Natural polysaccharides are extensively used in pharmaceutical and biomedical fields as carriers of diverse therapeutics and in tissue engineering applications. Apart from their biocompatibility and biodegradability, they can be tailored as per the specific requirements of the delivery carriers. Metal ion cross-linking of polysaccharide chains is a major tailoring technique which alters the rheological, mechanical, tensile, and other physicochemical attributes of the polysaccharides. Metal ions interact with the specific functional groups (carboxyl or sulphate) present in the polysaccharide chains to form water insoluble hydrogels, leading to structural stabilization of the polysaccharides. The concentration and valency of the ions dictate the porosity, rigidity, physicochemical, rheological, and mechanical characteristics of the cross-linked polysaccharide chains, paving the way for tailor-made formulations and delivery carriers. The review aims to explore the role of metal ions in the development of polysaccharide-based tailored matrix/medium. The article will provide comprehensive insights on how metal ions alter the swelling, porosity, mechanical, and dissolution properties of the polysaccharide chains. Finally, the review will serve as a groundwork resource providing valuable insights that can guide researchers in the fundamentals of their projects accordingly, such as achieving predetermined outcomes in areas like drug and cell delivery, tissue engineering, etc.

Rubidium ions as a novel therapeutic approach for glioblastoma

Glioblastoma (GBM) is a highly aggressive brain tumor with limited treatment options, mainly due to challenges such as incomplete resection and blood-brain barrier limitations. Rubidium, a naturally occurring alkali metal with favorable biocompatibility, widely used in myocardial and tumor perfusion imaging as a blood flow tracer, is repurposed in this study to investigate its potential therapeutic effects and mechanisms against GBM. The impacts of rubidium ions (Rb⁺) on GBM cells were assessed through functional assays evaluating proliferation, migration, invasion, and apoptosis. RNA sequencing and Western blot analyses were employed to investigate molecular mechanisms, while in vivo models were used to evaluate therapeutic efficacy and safety. Rb⁺ treatment significantly suppressed GBM cell proliferation, migration, and invasion, while inducing apoptosis and cell cycle arrest at the G2/M phase. Mechanistic studies revealed that Rb⁺ downregulated the phosphatidylinositol 3-kinase/protein kinase B/mammalian target of rapamycin (PI3K/AKT/mTOR) pathway, contributing to the induction of apoptosis in tumor cells. In vivo, Rb⁺ exhibited potent anti-tumor activity with no detectable adverse effects on major organs, physiological functions, or behavior in mice. Our findings highlight Rb⁺ as a promising and innovative candidate for GBM therapy, leveraging the PI3K/AKT/mTOR pathway to inhibit tumor growth and promote apoptosis. This study underscores the potential of Rb⁺ in addressing the urgent need for novel GBM treatments, warranting further preclinical and clinical investigations.

Half-Sandwich Organometallic Ir(III) and Ru(II) Compounds and their Interactions with Biomolecules

This review highlights how a Ir(III) and Ru(II) coordination complexes can change theirs cytotoxic activity by interacting with a biomolecules such as deoxyribonucleic acid (DNA), human albumins (HSA), nicotinamide adenine dinucleotide (NADH), and glutathione (GSH). We have selected biomolecules (DNA, NADH, GSH, and HSA) based on their significant biological roles and importance in cellular processes. Moreover, this review may provide useful information for the development of new half-sandwich Ir(III) and Ru(II) complexes with desired properties and relevant biological activities. Additionally, the examples discussed here may help us better understand what happens to a metal-based drug once it enters the body.

Deep learning based on intratumoral heterogeneity predicts histopathologic grade of hepatocellular carcinoma

OBJECTIVES

The potential of medical imaging to non-invasively assess intratumoral heterogeneity (ITH) is increasingly being recognized. This study aimed to investigate the value of the ITH-based deep learning model for preoperative prediction of histopathologic grade in hepatocellular carcinoma (HCC).

MATERIALS AND METHODS

A total of 858 patients from primary cohort and two external cohorts were included. 3.0T or 1.5T axial portal venous phase MRI images were collected. We conducted radiomics feature-driven K-means clustering for automatic partition to reveal ITH. 2.5D and 3D deep learning models based on ResNet architecture were trained to extract deep learning hidden features of each subregion. The selected features were used to train Random Forest classifier, which constructed the feature-fusion model.

RESULTS

The extracted voxel-level radiomics features were unsupervised clustered by K-means to generate three subregions. In the 2.5D deep learning, the feature-fusion model based on ITH had superior predictive efficacy than the whole-tumor model (AUC: 0.82 vs. 0.72; p = 0.004). Even in the validation and external test sets, this model maintained a high AUC of 0.78-0.83, and net reclassification indices indicated that it could improve prediction by 25-28%. Regarding the prognostic value, overall survival (OS) and recurrence-free survival (RFS) could be significantly stratified by the 2.5D feature-fusion model, and multivariable Cox regressions indicated its signature was identified as a risk predictor for OS and RFS (p < 0.05).

CONCLUSION

The ITH-based feature-fusion model provided a non-invasive method for classifying tumor differentiation in HCC, which may serve as a promising strategy for stratification management.

Developing dual-responsive quinolinium prodrugs of 8-hydroxyquinoline by harnessing the dual chelating sites

The bidentate metal ion chelator 8-hydroxyquinoline (8-HQ) demonstrates significant potential in anticancer therapy but is hindered by adverse effects due to nonspecific chelation in normal tissues. The phenolic hydroxyl oxygen of 8-HQ has been extensively exploited to develop O-masked 8-HQ prodrugs aimed at achieving on-demand chelation. However, the equally crucial quinoline nitrogen for chelation remains underutilized. By alkylating the quinoline nitrogen of 8-HQ, we synthesized a series of N-masked quinolinium (QUM) prodrugs that release 8-HQ upon activation by various stimuli. Comprehensive in vitro and in vivo studies were conducted with QUM-1 and QUM-4, which are activated by H2O2 and β-glucosidase, respectively. Both QUM-1 and QUM-4 exhibit improved cancer cell selectivity compared to 8-HQ or the O-masked isomeric prodrug, attributed to unique properties such as enhanced mitochondrial targeting and increased glucose transporter-mediated cellular uptake. Additionally, by leveraging both chelating sites, we constructed dual-masked 8-HQ prodrugs that are activated non-sequentially by two stimuli to release 8-HQ. QUM-5 demonstrates anticancer activity upon activation by UV/H2O2 and shows improved safety in mice compared to 8-HQ. Our research presents novel applications for the construction of quaternary ammonium prodrugs utilizing aromatic tertiary amines and underscores the potential of dual-responsive prochelators for targeted cancer therapy.

Programmed cell death in nasopharyngeal carcinoma: Mechanisms and therapeutic targets

Programmed cell death is a type of autonomic and orderly cell death mode controlled by genes that maintain homeostasis and growth. Tumor is a typical manifestation of an imbalance in environmental homeostasis in the human body. Currently, several tumor treatments are designed to trigger the death of tumor cells. Nasopharyngeal carcinoma is one of the most common malignant tumors in China. It displays obvious regional and ethnic differences in its incidence, being typically high in the south and low in the north of China. Nasopharyngeal carcinoma is currently considered to be a polygenic inherited disease and is often mediated by the interaction between multiple genes or between genes and the environment. Apoptosis has long been considered the key to tumor treatment, while other cell death pathways have often been overlooked. The current study provides an overview of the relationship among apoptosis, autophagy, pyroptosis, necroptosis, ferroptosis, and nasopharyngeal carcinoma, and the regulatory pathways of nasopharyngeal carcinoma based on five cell death modes were synthesized from the view of molecule. We hope this review will help explore additional, novel programmed cell death targets for the treatment of nasopharyngeal carcinoma and thus promote in-depth research.

A Metal Chelation Therapy to Effectively Eliminate Breast Cancer and Intratumor Bacteria While Suppressing Tumor Metastasis by Copper Depletion and Zinc Ions Surge

The intratumor microbiota results in the immunosuppressive microenvironment and facilitates tumor growth and metastasis. However, developing a synergistic therapy with antitumor, antibacterial, and antimetastatic effects faces enormous challenges. Here, we propose an innovative metal chelation therapy to effectively eliminate tumor and intratumor bacteria and suppress tumor metastasis. Different from traditional chelation therapy that only consumes metal elements, this therapy not only eliminates the crucial metal elements for tumor metabolism but also releases new metal ions with antitumor and antibacterial properties. Based on the high demand for copper in breast cancer, we prepare a fibrous therapeutic nanoagent (Zn-PEN) by chelating the copper chelator D-Penicillamine (D-PEN) with Zn2+. Firstly, Zn-PEN achieves dual inhibition of oxidative phosphorylation (OXPHOS) and glycolysis metabolism in breast cancer through copper depletion and Zn2+ activated cGAS-STING pathway, thus inducing tumor cell death. Secondly, Zn-PEN has the capability to eradicate Fusobacterium nucleatum (F. nucleatum) in breast cancer, thereby mitigating its immunosuppressive impact on the tumor microenvironment. Finally, Zn-PEN effectively inhibits tumor metastasis through multiple routes, including the inhibition of epithelial-mesenchymal transition (EMT) process, activation of cGAS-STING pathway, and elimination with F. nucleatum. Therefore, we verify the feasibility of Zn-PEN mediated metal chelation therapy in a 4T1 model infected with F. nucleatum, providing a new therapeutic strategy for inhibiting tumor metastasis.

Structure-property relations in rheology of cellulose nanofibrils-based hydrogels

Hydrogels prepared from self-assembled cellulose nanofibrils (CNFs) are widely used in biomedicine, electronics and environmental technology. Their ability to serve as inks for extrusion-based 3D printing is conventionally evaluated by means of rheological tests. A model is developed that describes the response of CNF gels in small- and large-amplitude oscillatory tests in a unified manner. The model involves a reasonably small number of material parameters, ensures good agreement between results of simulation and observations in oscillatory tests and correctly predicts the stress-strain Lissajous curves, experimental data in hysteresis loop tests, and measurements of the steady-state viscosity. The model is applied to analyze how composition and preparation conditions for CNF gels affect transition from shear thinning to weak strain overshoot in large-amplitude shear oscillatory tests. Based on the model, simple relations are derived for the fractal dimension of CNF clusters and the storage modulus of gels prepared in aqueous solutions of multivalent salts. The validity of these equations is confirmed by comparison of their predictions with observations in independent tests.

A Preliminary Investigation of Thermally Stable Schiff Base Metal Complexes for Hyperthermia: Synthesis and Biological Evaluation

A novel Schiff base ligand (L), bearing N2O2 donor sites, was derived from the condensation of 5-chloromethylisophthaldehyde and phenylpropanolamine (PPA). Mononuclear Co(II), Cu(II), and Zn(II) complexes were synthesized and were characterized by FTIR, UV-Vis, 1H NMR, ESI-mass spectroscopy, molar conductance, and thermal and electrochemical studies. The thermal investigation revealed that the complexes were stable up to 150-250 °C and began to degrade in stages, resulting in the development of respective metal oxides. The Coats-Redfern integration method was used to calculate the kinetic and thermodynamic parameters, the energy of activation (Ea), and changes in enthalpy (∆H), entropy (∆S), and free energy (∆G) for each step of the degradation processes. For stage I decomposition, the calculated activation energy values of the complexes follow the order of Ea [Cu(L)] > Ea [Co(L)(H2O)2] > Ea [Zn(L)]. The influence of the temperature on the efficacy of antioxidant activities of the complexes with DPPH assay, ABTS assay, and hydroxy radical assay was investigated at various concentrations using ascorbic acid (AA) as the reference. Antioxidant activity was assessed at multiple temperatures to ascertain whether these complexes may be applied in radiation therapy enhanced with hyperthermia and found to be stable. Subsequently, the Cu(II) complex (C2) demonstrated a greater cytotoxicity (IC50 = 5.16 µM) than Co(II), Zn(II), and conventional cisplatin when in vitro cytotoxicity was evaluated against the MCF-7 cell line using the MTT method. Analyses of the thermal stability and ROS scavenging ability of complexes have demonstrated that these complexes have potential in hyperthermic radiation therapy.

Chaperone-Derived Copper(I)-Binding Peptide Nanofibers Disrupt Copper Homeostasis in Cancer Cells

Copper (Cu) is a transition metal that plays crucial roles in cellular metabolism. Cu+ homeostasis is upregulated in many cancers and contributes to tumorigenesis. However, therapeutic strategies to target Cu+ homeostasis in cancer cells are rarely explored because small molecule Cu+ chelators have poor binding affinity in comparison to the intracellular Cu+ chaperones, enzymes, or ligands. To address this challenge, we introduce a Cu+ chaperone-inspired supramolecular approach to disrupt Cu+ homeostasis in cancer cells that induces programmed cell death. The Nap-FFMTCGGCR peptide self-assembles into nanofibers inside cancer cells with high binding affinity and selectivity for Cu+ due to the presence of the unique MTCGGC motif, which is conserved in intracellular Cu+ chaperones. Nap-FFMTCGGCR exhibits cytotoxicity towards triple negative breast cancer cells (MDA-MB-231), impairs the activity of Cu+ dependent co-chaperone super oxide dismutase1 (SOD1), and induces oxidative stress. In contrast, Nap-FFMTCGGCR has minimal impact on normal HEK 293T cells. Control peptides show that the self-assembly and Cu+ binding must work in synergy to successfully disrupt Cu+ homeostasis. We show that assembly-enhanced affinity for metal ions opens new therapeutic strategies to address disease-relevant metal ion homeostasis.

Mechanisms of H2pmen-Induced cell death: Necroptosis and apoptosis in MDA cells, necrosis in MCF7 cells

Breast cancer is the second leading cause of cancer-related deaths in women around the world. Several cancer therapeutics have already been discovered and are being used to treat breast cancer. However, most of them cause severe side effects. H2pmen, a tetradentate ligand, was used in this study to investigate its cytotoxic effects on growth, viability, and induction of cell death in MCF7 and MDA cells. The cell viability was determined by treating cells with different concentrations of H2pmen. MTT assay was used to obtain an IC50, and the cells were then assayed for membrane damage, apoptotic induction, and metabolism. Protein expression of Bax, p53, Bcl2, and xIAP was identified using Western blot analysis. The gene expression of RIPK1, RIPK3, and MKLK was determined using qPCR. In MDA cells, H2pmen increases cytotoxicity, as evidenced by upregulated LDH and JC-10, and enhances apoptosis, indicated by upregulated caspase-3/7 and Bax. In contrast, MCF7 cells exhibit a more stable profile with downregulated LDH and Annexin V Activity. MCF7 cells also show reduced necroptosis and increased necrosis. These findings highlight that H2pmen induces varied cytotoxic effects across MDA and MCF7 cells, with MDA cells exhibiting more pronounced apoptosis and necroptosis alongside complex anti-apoptotic responses.

An encounter between metal ions and natural products: natural products-coordinated metal ions for the diagnosis and treatment of tumors

Natural products-coordinated metal ions to form the nanomedicines are in the spotlight for cancer therapy. Some natural products could be coordinated with metal ions forming nanomedicines via simple and green environmental self-assembly, which not only improved the bioavailability of natural products, but also conferred multiple therapeutic modalities and multimodal imaging. On the one hand, in the weak acidity, glutathione (GSH) and hydrogen peroxide (H2O2) overexpression of tumor microenvironment (TME), such carrier-free nanomedicines could be further enhanced the therapeutic effect via optimizing the species of metal ions. On the other hand, nanomedicines could exert the precise treatment of tumor under the guidance of multiple imaging. Hence, this review summarized the research progress in recent years on the application of natural product-coordinated metal ions in cancer therapy. In addition, the prospects and challenges for the application of natural product-coordinated metal ions were discussed, especially how to improve targeting ability and stability and assess the safety of metal ions, so as to facilitate the clinical translation and application of natural product-coordinated metal ions nanomedicines.

Bimetallic peroxide nanoparticles induce PANoptosis by disrupting ion homeostasis for enhanced immunotherapy

PANoptosis has recently emerged as a potential approach to improve the immune microenvironment. However, current methods for inducing PANoptosis are limited. Herein, through biological screening, the rational use of the nutrient metal ions Cu2+ and Zn2+ had great potential to induce PANoptosis. Inspired by these findings, we successfully developed hydrazided hyaluronic acid-modified zinc copper oxide (HZCO) nanoparticles as a PANoptosis inducer to potentiate immunotherapy. Bioactive HZCO actively delivered Cu2+ and Zn2+ while disrupting the cellular intrinsic ion metabolism pathway, resulting in double-stranded DNA release and organelle damage in cancer cells. Simultaneously, this process triggered the formation of PANoptosome and the activation of PANoptosis. HZCO-induced PANoptosis inhibited tumor growth and activated potent antitumor immune response, thereby enhancing the effectiveness of anti-programmed cell death 1 therapy. Overall, our work provides an insight into the development of PANoptosis inducers and the design of synergistic immunotherapy strategies.

Synergistic immunotherapy with a calcium-based nanoinducer: evoking pyroptosis and remodeling tumor-associated macrophages for enhanced antitumor immune response

The challenges posed by low immunogenicity and the immunosuppressive tumor microenvironment (TME) significantly hinder the efficacy of cancer immunotherapy. Pyroptosis, characterized as a pro-inflammatory cell death pathway, emerges as a promising approach to augment immunotherapy by promoting immunogenic cell death (ICD). The predominance of M2 phenotype tumor-associated macrophages (TAMs) in the TME underscores the critical need for TAM reprogramming to mitigate this immunosuppression. Herein, we introduce a calcium-based, intelligent-responsive nanoinducer (CaZCH NPs), designed to concurrently initiate pyroptosis and remodel TAMs, thereby amplifying antitumor immunotherapy effects. Modified with hyaluronic acid, CaZCH NPs can target tumor cells. Once internalized, CaZCH NPs respond to the acidic environment, releasing Ca2+, curcumin and H2O2 to induce mitochondrial Ca2+ overload and oxidation stress, leading to caspase-3/GSDME-mediated cell pyroptosis. Concurrently, O2 produced by CaZCH and pro-inflammatory cytokines from pyroptotic cells work together to shift TAM polarization towards the M1 phenotype, effectively countering TME's immunosuppressive effect. Notably, the synergistic effect of Ca2+-mediated pyroptosis and TAM remodeling demonstrates superior antitumor efficiency in colorectal cancer models. The induced ICD, coupled with M1-type TAMs, effectively enhances immunogenicity and mitigates immunosuppression, promoting dendritic cell maturation and activating CD8+ T cell-dependent systemic antitumor immunity. Our study presents a promising synergistic strategy for achieving highly efficient immunotherapy using a simple calcium-based nanoinducer.

Bone targeted nano-drug and nano-delivery

There are currently no targeted delivery systems to satisfactorily treat bone-related disorders. Many clinical drugs consisting of small organic molecules have a short circulation half-life and do not effectively reach the diseased tissue site. This coupled with repeatedly high dose usage that leads to severe side effects. With the advance in nanotechnology, drugs contained within a nano-delivery device or drugs aggregated into nanoparticles (nano-drugs) have shown promises in targeted drug delivery. The ability to design nanoparticles to target bone has attracted many researchers to develop new systems for treating bone related diseases and even repurposing current drug therapies. In this review, we shall summarise the latest progress in this area and present a perspective for future development in the field. We will focus on calcium-based nanoparticle systems that modulate calcium metabolism and consequently, the bone microenvironment to inhibit disease progression (including cancer). We shall also review the bone affinity drug family, bisphosphonates, as both a nano-drug and nano-delivery system for bone targeted therapy. The ability to target and release the drug in a controlled manner at the disease site represents a promising safe therapy to treat bone diseases in the future.

A Novel CaCu-Metal-Organic-Framework Based Multimodal Treatment Platform for Enhanced Synergistic Therapy of Hepatocellular Carcinoma

Metal ions have attracted a lot of interest in antitumor therapy due to their unique mechanism of action. However, multiple death mechanisms associate with metal ions to synergistic antitumors have few studies mainly due to the serious challenges in designing and building metal-associated multimodal treatment platforms. Hence, a series of glutathione-activatable CaCu-based metal-organic-frameworks loaded with doxorubicin and ovalbumin are successfully designed and synthesized with an "all in one" strategy, which is modified by galactosamine-linked hyaluronic acid to prepare multimodal treatment platform (SCC/DOX@OVA-HG) for targeted delivery and synergistic antitumor therapy. SCC/DOX@OVA-HG can be rapidly degraded by the overexpressed glutathione and then releases the "cargoes" in the tumor microenvironment. The released Cu+ efficiently catalyzes H2O2 to produce highly toxic ROS for CDT, and the up-regulation of calcium ion concentration in tumor cells induced by the released Ca2+ enables calcium overload therapy, which synergically enhances the metal-related death pattern. Meanwhile, OVA combined with Ca2+/Cu2+ further activates macrophages into an M1-like phenotype to accelerate tumor cell death through immunotherapy. Besides, the released DOX can also insert into the DNA double helix for chemotherapy. Consequently, the developed SCC/DOX@OVA-HG reveals significantly improved antitumor efficacy through a multimodal synergistic therapy of chemotherapy, chemodynamic therapy, calcium overload, and immunotherapy.

Copper-mediated siRNA activation for conditional control of gene expression

Copper plays a crucial role in maintaining biological redox balance in living organisms, with elevated levels observed in cancer cells. Short interfering RNAs (siRNAs) are effective in gene silencing and find applications as both research tools and therapeutic agents. A method to regulate RNA interference using copper is especially advantageous for cancer-specific therapy. We present a chemical approach of selective siRNA activation triggered by intracellular copper ions. We designed and synthesized nucleotides containing copper-responsive moieties, which were incorporated into siRNAs. These copper-responsive siRNAs effectively silenced the target cyclin B1 mRNA in living cells. This pioneering study introduces a novel method for conditionally controlling gene silencing using biologically relevant metal ions in human cells, thereby expanding the repertoire of chemical knockdown tools.

Mechanism of metal ion-induced cell death in gastrointestinal cancer

Gastrointestinal (GI) cancer is one of the most severe types of cancer, with a significant impact on human health worldwide. Due to the urgent demand for more effective therapeutic strategies against GI cancers, novel research on metal ions for treating GI cancers has attracted increasing attention. Currently, with accumulating research on the relationship between metal ions and cancer therapy, several metal ions have been discovered to induce cell death. In particular, the three novel modes of cell death, including ferroptosis, cuproptosis, and calcicoptosis, have become focal points of research in the field of cancer. Meanwhile, other metal ions have also been found to trigger cell death through various mechanisms. Accordingly, this review focuses on the mechanisms of metal ion-induced cell death in GI cancers, hoping to provide theoretical support for further GI cancer therapies.

Tyrosine kinase inhibitors (TKIs) for ovarian cancer treatment: from organic to inorganic chemotherapeutics towards selectivity-a perspective overview

Ovarian cancer (OC) is a lethal gynecologic cancer in industrialized countries. Treatments for OC include the surgical removal and chemotherapy. In the last decades, improvements have been made in the surgery technologies, drug combinations and administration protocols, and in diagnosis. However, mortality from OC is still high owing to recurrences and insurgence of drug resistance. Accordingly, it is urgent the development of novel agents capable to effectively target OC. In this respect, tyrosine kinase inhibitors (TKIs) may play an important role. Most of TKIs developed and tested so far are organic. However, owing to their chemical versatility, also metals can be exploited to design selective and potent TKIs. We provide a short and easy-to-read overview on the main organic TKIs with a summary of those that entered clinical trials. Additionally, we describe the potential of metal-based TKIs, focusing on this overlooked family of compounds that may significantly contribute towards the concept of precision-medicine.

Recent advances in nanomedicine for metabolism-targeted cancer therapy

Metabolism denotes the sum of biochemical reactions that maintain cellular function. Different from most normal differentiated cells, cancer cells adopt altered metabolic pathways to support malignant properties. Typically, almost all cancer cells need a large number of proteins, lipids, nucleotides, and energy in the form of ATP to support rapid division. Therefore, targeting tumour metabolism has been suggested as a generic and effective therapy strategy. With the rapid development of nanotechnology, nanomedicine promises to have a revolutionary impact on clinical cancer therapy due to many merits such as targeting, improved bioavailability, controllable drug release, and potentially personalized treatment compared to conventional drugs. This review comprehensively elucidates recent advances of nanomedicine in targeting important metabolites such as glucose, glutamine, lactate, cholesterol, and nucleotide for effective cancer therapy. Furthermore, the challenges and future development in this area are also discussed.

Controlled Sr(ii) ion release from in situ crosslinking electroactive hydrogels with potential for the treatment of infections

The development of electrochemical stimuli-responsive drug delivery systems is of both academic and industrial interest due to the ease with which it is possible to trigger payload release, providing drug delivery in a controllable manner. Herein, the preparation of in situ forming hydrogels including electroactive polypyrrole nanoparticles (PPy-NPs) where Sr2+ ions are electrochemically loaded for electrically triggered release of Sr2+ ions is reported. The hydrogels were characterized by a variety of techniques including Fourier-transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), thermogravimetric analysis (TGA), X-ray diffraction (XRD), cyclic voltammetry (CV), etc. The cytocompatibility towards human mesenchymal stem cells (MSCs) and fibroblasts were also studied. The Sr2+ ion loaded PEC-ALD/CS/PPy-NPs hydrogel showed no significant cytotoxicity towards human mesenchymal stem cells (MSCs) and fibroblasts. Sr2+ ions were electrochemically loaded and released from the electroactive hydrogels, and the application of an electrical stimulus enhanced the release of Sr2+ ions from gels by ca. 2-4 fold relative to the passive release control experiment. The antibacterial activity of Sr2+ ions against E. coli and S. aureus was demonstrated in vitro. Although these prototypical examples of Sr2+ loaded electroactive gels don't release sufficient Sr2+ ions to show antibacterial activity against E. coli and S. aureus, we believe future iterations with optimised physical properties of the gels will be capable of doing so.

Fluorinated Iron Metal-Organic Frameworks for Activatable 19F Magnetic Resonance Imaging and Synergistic Therapy of Tumors

Due to their appealing physiochemical properties, metal-organic frameworks (MOFs) have been widely employed in biomedical fields. In this study, we utilize ferric ions and fluorine-containing organic ligands as both structural and functional units to develop a stimulus-responsive nanoagent, 19FIMOF-TA nanoparticles, for activatable 19F magnetic resonance imaging (MRI) and synergistic therapy of tumors. This nanoagent could respond to excess GSH in a tumor microenvironment, discharging fluorinated organic ligands and reduced ferrous ions. The release of these fluorine-containing small molecules results in boosting of the 19F MRI signals, which could be further enhanced by the photothermal effect of this nanoagent to achieve a responsive cascaded amplification of 19F MRI signals for tumor visualization. Meanwhile, ferroptosis promoted by the ferrous ions leads to significant tumor cell death, which is synergistically aggravated by the photothermal effect. The encouraging results illustrate the promising potential of our nanoagent for effective tumor imaging and combinative cancer therapy.

Rational Design of Guanidinium-Based Bio-MCOF as a Multifunctional Nanocatalyst in Tumor Cells for Enhanced Chemodynamic Therapy

Chemodynamic therapy (CDT) has emerged as a promising approach to cancer treatment, which can break the intracellular redox state balance and result in severe oxidative damage to biomolecules and organelles with the advantages of being less dependent on external stimulation, having deep tissue-healing abilities, and being resistant to drug resistance. There is considerable interest in developing CDT drugs with high efficiency and low toxicity. In this study, a new guanidinium-based biological metal covalent organic framework (Bio-MCOF), GZHMU-1@Mo, is rationally designed and synthesized as a multifunctional nanocatalyst in tumor cells for enhanced CDT. The DFT calculation and experimental results showed that due to the ability of MoO42- ion to promote electron transfer and increase the redox active site, Cu3 clusters and MoO42- ions in GZHMU-1@Mo can synergistically catalyze the production of reactive oxygen species (ROS) from oxygen and H2O2 in tumor cells, as well as degrade intracellular reducing substances, GSH and NADH, so as to disrupt the redox balance in tumor cells. Moreover, GZHMU-1@Mo exhibits a potent killing effect on tumor cells under both normal oxygen and anaerobic conditions. Further in vitro and in vivo antiproliferation studies revealed that the GZHMU-1@Mo nanoagent displays a remarkable antiproliferation effect and effectively inhibits tumor growth. Taken together, our study provides an insightful reference benchmark for the rational design of Bio-MCOF-based nanoagents with efficient CDT.

Metal ions as effectual tools for cancer with traditional Chinese medicine

Malignant tumor has become a major threat affecting human health, and is one of the main causes of human death. Recent studies have shown that many traditional Chinese medicines (TCM) have good anti-tumor activity, which may improve the therapeutic effect of routine treatment and quality of life with lower toxicity. However, the efficacy of TCM alone for the treatment of tumors is limited. Metal ions are essential substances for maintaining normal physiological activities. This article summarized the multiple mechanisms in which metal ions are involved in the prevention and treatment of tumors in TCM.

Mild-Photothermal Effect Induced High Efficiency Ferroptosis-Boosted-Cuproptosis Based on Cu2 O@Mn3 Cu3 O8 Nanozyme

A core-shell-structured Cu2 O@Mn3 Cu3 O8 (CMCO) nanozyme is constructed to serve as a tumor microenvironment (TME)-activated copper ionophore to achieve safe and efficient cuproptosis. The Mn3 Cu3 O8 shell not only prevents exposure of normal tissues to the Cu2 O core to reduce systemic toxicity but also exhibits enhanced enzyme-mimicking activity owing to the better band continuity near the Fermi surface. The glutathione oxidase (GSHOx)-like activity of CMCO depletes glutathione (GSH), which diminishes the ability to chelate Cu ions, thereby exerting Cu toxicity and inducing cuproptosis in cancer cells. The catalase (CAT)-like activity catalyzes the overexpressed H2 O2 in the TME, thereby generating O2 in the tricarboxylic acid (TCA) cycle to enhance cuproptosis. More importantly, the Fenton-like reaction based on the release of Mn ions and the inactivation of glutathione peroxidase 4 induced by the elimination of GSH results in ferroptosis, accompanied by the accumulation of lipid peroxidation and reactive oxygen species that can cleave stress-induced heat shock proteins to compromise their protective capacity of cancer cells and further sensitize cuproptosis. CMCO nanozymes are partially sulfurized by hydrogen sulfide in the colorectal TME, exhibiting excellent photothermal properties and enzyme-mimicking activity. The mild photothermal effect enhances the enzyme-mimicking activity of the CMCO nanozymes, thus inducing high-efficiency ferroptosis-boosted-cuproptosis.

Trinuclear rhenium(I)-based metallocages as anticancer agents towards human cervical cancer cells

The first examples of spherical-shaped trinuclear rhenium(I) organometallic cages displaying cytotoxic, antimetastatic, antiproliferative and DNA-damaging behavior towards a human cervical (HeLa) cancer cell line are reported. The compact design of the metallocages facilitates their interactions with biosystems leading to comparable efficiency to that of the commonly used anticancer drug cisplatin.

A new family of luminescent [Pt(pbt)2(C6F5)L]n+ (n = 1, 0) complexes: synthesis, optical and cytotoxic studies

Given the widely recognized bioactivity of 2-arylbenzothiazoles against tumor cells, we have designed a new family of luminescent heteroleptic pentafluorophenyl-bis(2-phenylbenzothiazolyl) PtIV derivatives, fac-[Pt(pbt)2(C6F5)L]n+ (n = 1, 0) [L = 4-Mepy 1, 4-pyridylbenzothiazole (pybt) 2, 4,4'-bipyridine (4,4'-bpy) 3, 1,2-bis-(4-pyridyl)ethylene (bpe) 4 (E/Z ratio: 90/10), 1,4-bis-(pyridyl)butadiyne (bpyb) 5, trifluoroacetate (-OCOCF3) 6] and a dinuclear complex [{Pt(pbt)2(C6F5)}2(μ-bpyb)](PF6)27, in which the trans ligand to the metalated C-(pbt) was varied to modify the optical properties and lipophilicity. Their photophysical properties were systematically studied through experimental and theoretical investigations, which were strongly dependent on the identity of the N-bonded ligand. Thus, complexes 1, 3 and 6 display, in different media, emission from the triplet excited states of primarily intraligand 3ILCT nature localized on the pbt ligand, while the emissions of 2, 5 and 7 were ascribed to a mixture of close 3IL'(N donor)/3ILCT(pbt) excited states, as supported by lifetime measurements and theoretical calculations. Irradiation of the initial E/Z mixture of 4 (15 min) led to a steady state composed of roughly 1 : 1.15 (E : Z) and this complex was not emissive at room temperature due to an enhanced intramolecular E to Z isomerization process of the 1,2-bis-(4-pyridyl)ethylene ligand. Complexes 1-3 and 6 showed excellent quantum yields for the generation of singlet oxygen in aerated MeCN solution with the values of ϕ(1O2) ranging from 0.66 to 0.86 using phenalenone as a reference. Cationic complexes 1-3 exhibited remarkable efficacy in the nanomolar range against A549 (lung carcinoma) and HeLa (cervix carcinoma) cell lines with notable selectivity relative to the non-tumorigenic BEAS-2B (bronchial epithelium) cells. In the A549 cell line, the neutral complex 6 showed low cytotoxicity (IC50: 29.40 μM) and high photocytotoxicity (IC50: 5.75) when cells were irradiated with blue light for 15 min. These complexes do not show evidence of DNA interaction.

Zn2+-interference and H2S-mediated gas therapy based on ZnS-tannic acid nanoparticles synergistic enhancement of cell apoptosis for specific treatment of prostate cancer

Zn²⁺ and H₂S are essential to maintain normal prostate function, and sometimes can evolve into weapons to attack and destroy prostate cancer (PCa) cells. Nevertheless, how to achieve the targeted and effective release of Zn²⁺ and H₂S, and reverse the concentration distribution within PCa tumor cells still highly challenging. Herein, combined with these pathological characteristics of prostate, we proposed a tumor microenvironment (TME) responsive Zn²⁺-interference and H₂S-mediated gas synergistic therapy strategy based on a nanoplatform of tannic acid (TA) modified zinc sulfide nanoparticles (ZnS@TA) for the specific treatment of PCa. Once the constructed pH-responsive ZnS@TA internalized by cancer cells, it would instantaneously decomposed in acidic TME, and explosively release excess Zn²⁺ and H₂S exceeding the cell self-regulation threshold. Meanwhile, the in situ produced Zn²⁺ and H₂S synergistic enhancement of cell apoptosis, which is evidenced to increase levels of Bax and Bax/Bcl-2 ratio, release of Cytochrome c in cancer cells, contributing to inhibit the growth of tumor. Moreover, the TA in cooperation with Zn²⁺ specifically limits the migration and invasion of PCa cells. Both in vitro and in vivo results demonstrate that the Zn²⁺-interference in combination with H₂S-mediated gas therapy achieves an excellent anti-tumor performance. Overall, this nanotheranostic synergistic therapy provides a promising direction for exploring new strategies for cancer treatment based on specific tumor pathological characteristics, and provides a new vision for promoting practical cancer therapy.

Lithium in Cancer Therapy: Friend or Foe?

Lithium, a trace element important for fetal health and development, is considered a metal drug with a well-established clinical regime, economical production process, and a mature storage system. Several studies have shown that lithium affects tumor development by regulating inositol monophosphate (IMPase) and glycogen synthase kinase-3 (GSK-3). Lithium can also promote proliferation and programmed cell death (PCD) in tumor cells through a number of new targets, such as the nuclear receptor NR4A1 and Hedgehog-Gli. Lithium may increase cancer treatment efficacy while reducing side effects, suggesting that it can be used as an adjunctive therapy. In this review, we summarize the effects of lithium on tumor progression and discuss the underlying mechanisms. Additionally, we discuss lithium's limitations in antitumor clinical applications, including its narrow therapeutic window and potential pro-cancer effects on the tumor immune system.

BSA-coated β-FeOOH nanoparticles efficiently deliver the photosensitizer chlorin e6 for synergistic anticancer PDT/CDT

Photodynamic therapy (PDT) has many exceptional advantages in cancer treatment, such as minor trauma, low toxicity side effects, and strong adaptability, effectively overcoming some obstacles of traditional therapy and providing more revolutionary opportunities for curing cancer. Chlorin e6 (Ce6) exhibits excellent singlet oxygen generation and conversion efficiency under near-infrared laser irradiation and is a promising PDT photosensitizer. However, its hydrophobicity, short half-life and lack of tumor specificity limit its in vivo anticancer application. Therefore, this work has designed and prepared a multifunctional nanoplatform, Ce6/FeOOH@BSA, to efficiently deliver Ce6. Nanoparticles exhibit excellent dispersion and stability in deionized water, PBS and DMEM, and the blood half-life is 3.98 ± 0.31 h. The nanoplatform demonstrates effective tumor targeting and accumulation, overcoming the obstacles of the biological application of Ce6. Iron ions can exert a chemodynamic therapy (CDT) effect by reacting with overexpressed H₂O₂ in the tumor to generate toxic hydroxyl radicals (·OH). Moreover, FeOOH nanoparticles effectively promote glutathione (GSH) consumption in tumor cells, which is conducive to accumulating reactive oxygen species (ROS). In brief, Ce6/FeOOH@BSA nanoparticles realize the targeted delivery of Ce6 and mediate synergistic PDT/CDT against tumors, broadening the biomedical application of nanomaterials.

Mitochondrial dysfunction-targeted nanosystems for precise tumor therapeutics

Mitochondria play critical roles in the regulation of the proliferation and apoptosis of cancerous cells. Targeted induction of mitochondrial dysfunction in cancer cells by multifunctional nanosystems for cancer treatment has attracted increasing attention in the past few years. Numerous therapeutic nanosystems have been designed for precise tumor therapy by inducing mitochondrial dysfunction, including reducing adenosine triphosphate, breaking redox homeostasis, inhibiting glycolysis, regulating proteins, membrane potential depolarization, mtDNA damage, mitophagy dysregulation and so on. Understanding the mechanisms of mitochondrial dysfunction would be helpful for efficient treatment of diseases and accelerating the translation of these therapeutic strategies into the clinic. Then, various strategies to construct mitochondria-targeted nanosystems and induce mitochondrial dysfunction are summarized, and the recent research progress regarding precise tumor therapeutics is highlighted. Finally, the major challenges and an outlook in this rapidly developing field are discussed. This review is expected to inspire further development of novel mitochondrial dysfunction-based strategies for precise treatments of cancer and other human diseases.

Trends in metabolic signaling pathways of tumor drug resistance: A scientometric analysis

Background

Cancer chemotherapy resistance is one of the most critical obstacles in cancer therapy. Since Warburg O first observed alterations in cancer metabolism in the 1950s, people gradually found tumor metabolism pathways play a fundamental role in regulating the response to chemotherapeutic drugs, and the attempts of targeting tumor energetics have shown promising preclinical outcomes in recent years. This study aimed to summarize the knowledge structure and identify emerging trends and potential hotspots in metabolic signaling pathways of tumor drug resistance research.

Methods

Publications related to metabolic signaling pathways of tumor drug resistance published from 1992 to 2022 were retrieved from the Web of Science Core Collection database. The document type was set to articles or reviews with language restriction to English. Two different scientometric software including Citespace and VOS viewer were used to conduct this scientometric analysis.

Results

A total of 2,537 publications including 1,704 articles and 833 reviews were retrieved in the final analysis. The USA made the most contributions to this field. The leading institution was the University of Texas MD Anderson Cancer Center. Avan A was the most productive author, and Hanahan D was the key researcher with the most co-citations, but there is no leader in this field yet. Cancers was the most influential academic journal, and Oncology was the most popular research field. Based on keywords occurrence analysis, these selected keywords could be roughly divided into five main topics: cluster 1 (study of cancer cell apoptosis pathway); cluster 2 (study of resistance mechanisms of different cancer types); cluster 3 (study of cancer stem cells); cluster 4 (study of tumor oxidative stress and inflammation signaling pathways); and cluster 5 (study of autophagy). The keywords burst detection identified several keywords as new research hotspots, including “tumor microenvironment,” “invasion,” and “target”.

Conclusion

Tumor metabolic reprogramming of drug resistance research is advancing rapidly. This study serves as a starting point, providing a thorough overview, the development landscape, and future opportunities in this field.

New anti-cancer explorations based on metal ions

Due to the urgent demand for more anti-cancer methods, the new applications of metal ions in cancer have attracted increasing attention. Especially the three kinds of the new mode of cell death, including ferroptosis, calcicoptosis, and cuproptosis, are of great concern. Meanwhile, many metal ions have been found to induce cell death through different approaches, such as interfering with osmotic pressure, triggering biocatalysis, activating immune pathways, and generating the prooxidant effect. Therefore, varieties of new strategies based on the above approaches have been studied and applied for anti-cancer applications. Moreover, many contrast agents based on metal ions have gradually become the core components of the bioimaging technologies, such as MRI, CT, and fluorescence imaging, which exhibit guiding significance for cancer diagnosis. Besides, the new nano-theranostic platforms based on metal ions have experimentally shown efficient response to endogenous and exogenous stimuli, which realizes simultaneous cancer therapy and diagnosis through a more controlled nano-system. However, most metal-based agents have still been in the early stages, and controlled clinical trials are necessary to confirm or not the current expectations. This article will focus on these new explorations based on metal ions, hoping to provide some theoretical support for more anti-cancer ideas.

Arsenic Prodrug-Mediated Tumor Microenvironment Modulation Platform for Synergetic Glioblastoma Therapy

Glioblastoma (GBM) has a distinct internal environment characterized by high levels of glutathione (GSH) and low oxygen partial pressure, which significantly restrict most drugs' effectiveness. Arsenic-based drugs are emerging candidates for treating solid tumors; however, relatively high doses in solo systems and inconsistent complementary systems severely damage the normal tissues. We proposed a novel covalently conjugated strategy for arsenic-based therapy via arsenic-boronic acid complex formation. The boronic acid was modified on silver (AgL) to capture As^V under an alkaline condition named arsenate plasmonic complex (APC) with a distinct Raman response. The APC can precisely release the captured As^V in lysosomal acidic pH that specifically targets TME to initiate a multimodal therapeutic effect such as GSH depletion and reactive oxygen species generation. In addition, GSH activation leads to subconverted As^V into As^III, which further facilitated glutathione peroxidase (GPx) and superoxide dismutase inhibition, whereas the tumor selective etching of the silver core triggered by endogenous H₂O₂ that can oxidize to generate highly toxic Ag ions produces and supplies O₂ to help the alleviated hypoxia. Both in vitro and in vivo data verify the APC-based chemotherapy paving the way for efficient nanomedicine-enabled boronate affinity-based arsenic chemotherapeutics for on demand site-specific cancer combination treatment of GBM tumors.

Zinc-doped Prussian blue nanoparticles for mutp53-carrying tumor ion interference and photothermal therapy

Quite a great proportion of known tumor cells carry mutation in TP53 gene, expressing mutant p53 proteins (mutp53) missing not only original genome protective activities but also acquiring gain-of-functions that favor tumor progression and impede treatment of cancers. Zinc ions were reported as agents cytocidal to mutp53-carrying cells by recovering p53 normal functions and abrogating mutp53. Meanwhile in a hyperthermia scenario, the function of wild type p53 is required to ablate tumors upon heat treatment hence the effects might be hindered in a mutp53 background. We herein synthesized zinc-doped Prussian blue (ZP) nanoparticles (NPs) to combine Zn²⁺ based and photothermal therapeutic effects. An efficient release of Zn²⁺ in a glutathione-enriched tumor intracellular microenvironment and a prominent photothermal conversion manifested ZP NPs as zinc ion carriers and photothermal agents. Apoptotic death and autophagic mutp53 elimination were found to be induced by ZP NPs in R280K mutp53-containing MDA-MB-231 cells and hyperthermia was rendered to ameliorate the treatment in vitro through further mutp53 elimination and increased cell death. The combinatorial therapeutic effect was also confirmed in vivo in a mouse model. This study might expand zinc delivery carriers and shed a light on potential interplay of hyperthermia and mutp53 degradation in cancer treatment.

Metallopolysaccharide-Based Smart Nanotheranostic for Imaging-Guided Precise Phototherapy and Sequential Enzyme-Activated Ferroptosis

Phototheranostic offers a regional-focused tumor treatment upon photoirradiation. However, it is difficult to completely eradicate solid tumors using a conventional phototheranostic owing to the residual tumor cells outside the laser irradiation range. Herein, we fabricated a metallopolysaccharide-based smart nanotheranostic (Fe-^dHA) via a nanoassembly-driven method, in which Fe³⁺ ions were coordinated to dopamine-modified biopolysaccharide hyaluronic acid (^dHA). Taking advantage of the structural backbone and intrinsic dual-information-related functions of HA as well as the bi-functional Fe(III)-coordination centers, Fe-^dHA can efficiently target tumor cells for phototheranostic. Additionally, it can be activated by endogenous overexpressed hyaluronidase to achieve sequential ferroptosis in tumor cells. The precise imaging and effective tumor inhibition using this metallopolysaccharide-based nanotheranostic were significantly demonstrated in vivo and in vitro. Thus, this rationally designed Fe-^dHA provided a simple metallopolysaccharide strategy to develop an "all-in-one" smart nanotheranostic to synergize different therapeutic modalities for improving cancer therapy.