Intra/Extracellular Lactic Acid Exhaustion for Synergistic Metabolic Therapy and Immunotherapy of Tumors

Self-Delivery Ternary Bioregulators for Photodynamic Amplified Immunotherapy by Tumor Microenvironment Reprogramming

Abnormal metabolism of cancer cells results in complex tumor microenvironments (TME), which play a dominant role in tumor metastasis. Herein, self-delivery ternary bioregulators (designated as TerBio) are constructed for photodynamic amplified immunotherapy against colorectal cancer by TME reprogramming. Specifically, carrier-free TerBio are prepared by the self-assembly of chlorine e6, SB505124 (SB), and lonidamine (Lon), which exhibit improved tumor accumulation, tumor penetration, and cellular uptake behaviors. Interestingly, TerBio-mediated photodynamic therapy (PDT) could not only inhibit the primary tumor growth but also induce immunogenic cell death of tumors to activate the cascade immune response. Furthermore, TerBio are capable of TME reprograming by SB-triggered transforming growth factor (TGF)-β blockage and Lon-induced lactic acid efflux inhibition. As a consequence, TerBio significantly suppresses distant and metastatic tumor growth by PDT-amplified immunotherapy. This study might advance the development of self-delivery nanomedicine against malignant tumor growth and metastasis.

Cycloruthenated Self-Assembly with Metabolic Inhibition to Efficiently Overcome Multidrug Resistance in Cancers

The synthesis and the evaluation of the efficacy of a cycloruthenated complex, RuZ, is reported, to overcome multi-drug resistance (MDR) in cancer cells. RuZ can self-assemble into nanoaggregates in the cell culture medium, resulting in a high intracellular concentration of RuZ in MDR cancer cells. The self-assembly significantly decreases oxygen consumption and inhibits glycolysis, which decreases cellular adenosine triphosphate (ATP) levels. The decrease in ATP levels and its low affinity for the ABCB1 and ABCG2 transporters (which mediate MDR) significantly increase the retention of RuZ by MDR cancer cells. Furthermore, RuZ increases cellular oxidative stress, inducing DNA damage, and, in combination with the aforementioned effects of RuZ, increases the apoptosis of cancer cells. Proteomic profiling analysis suggests that the RuZ primarily decreases the expression of proteins that mediate glycolysis and aerobic mitochondrial respiration and increases the expression of proteins involved in apoptosis. RuZ inhibits the proliferation of 35 cancer cell lines, of which 7 cell lines are resistant to clinical drugs. It is also active in doxorubicin-resistant MDA-MB-231/Adr mouse tumor xenografts. To the best of our knowledge, the results are the first to show that self-assembled cycloruthenated complexes are efficacious in inhibiting the growth of MDR cancer cells.

Coordination Polymer-Coated CaCO3 Reinforces Radiotherapy by Reprogramming the Immunosuppressive Metabolic Microenvironment

Radiotherapy is widely exploited for the treatment of a large range of cancers in clinic, but its therapeutic effectiveness is seriously crippled by the tumor immunosuppression, mainly driven by the altered metabolism of cancer cells. Here, a pH-responsive nanomedicine is prepared by coating calcium carbonate (CaCO₃ ) nanoparticles with 4-phenylimidazole (4PI), an inhibitor against indoleamine 2,3-dioxygenase 1 (IDO-1), together with zinc ions via the coordination reaction, aiming at reinforcing the treatment outcome of radiotherapy. The obtained pH-responsive nanomedicine, coined as acidity-IDO1-modulation nanoparticles (AIM NPs), is able to instantly neutralize protons, and release 4PI to suppress the IDO1-mediated production of kynurenine (Kyn) upon tumor accumulation. As a result, treatment with AIM NPs can remarkably enhance the therapeutic efficacy of radiotherapy against both murine CT26 and 4T1 tumors by eliciting potent antitumor immunity. Furthermore, it is shown that such combination treatment can effectively suppress the growth of untreated distant tumors via the abscopal effect, and result in immune memory responses to reject rechallenged tumors. This work highlights a novel strategy of simultaneous tumor acidity neutralization and IDO1 inhibition to potentiate radiotherapy, with great promises to suppress tumor metastasis and recurrence by eliciting robust antitumor immunity.

Tumor-Microenvironment-Activated Reactive Oxygen Species Amplifier for Enzymatic Cascade Cancer Starvation/Chemodynamic /Immunotherapy

At present, some progress has been made in the field of cancer theranostics based on nanocatalysts (NCs), but achieving precise theranostics in response to the specific tumor microenvironment (TME) remains a major challenge. Herein, a TME-responsive upconversion nanoparticles (UCNPs)-based smart UCNPs@Cu-Cys-GOx (UCCG) nanosystem is engineered, which combines natural enzymes and nanozymes so as to amplify reactive oxygen species (ROS) generation in situ for cancer starvation/chemodynamic/immunotherapy. One of the biggest merits of this material is that it can be preserved inert (off) in normal tissues, and only in the TME can it be specifically activated (on) through a series of enzymatic cascades to boost ROS production via a strategy of open source (H₂ O₂ self-supplying ability) and reduce expenditure (glutathione (GSH) consuming ability). More importantly, the enhanced oxidative stress by UCCG NCs reverses the immunosuppressive TME, and facilitates antitumor immune responses. Meanwhile, the starvation/chemodynamic synergistic therapy triggered by UCCG combined with PD-L1 antibody effectively inhibits the growth of primary tumors and cancer metastasis. In addition, the UCNPs in UCCG present upconversion luminescence enhancement, which can be exploited to visualize the reinforced ROS generation in real time. Collectively, this work provides an original method for the devising and exploitation of UCNPs-based catalytic immunotherapy.

Tumor-derived biomimetic nanozyme with immune evasion ability for synergistically enhanced low dose radiotherapy

High doses of radiation can cause serious side effects and efficient radiosensitizers are urgently needed. To overcome this problem, we developed a biomimetic nanozyme system (CF) by coating pyrite (FeS2) into tumor-derived exosomes for enhanced low-dose radiotherapy (RT). CF system give FeS2 with immune escape and homologous targeting abilities. After administration, CF with both glutathione oxidase (GSH-OXD) and peroxidase (POD) activities can significantly lower the content of GSH in tumor tissues and catalyze intracellular hydrogen peroxide (H2O2) to produce a large amount of ·OH for intracellular redox homeostasis disruption and mitochondria destruction, thus reducing RT resistance. Experiments in vivo and in vitro showed that combining CF with RT (2 Gy) can provide a substantial suppression of tumor proliferation. This is the first attempt to use exosomes bionic FeS2 nanozyme for realizing low-dose RT, which broaden the prospects of nanozymes.

Nanofactory for metabolic and chemodynamic therapy: pro-tumor lactate trapping and anti-tumor ROS transition

Lactate plays a critical role in tumorigenesis, invasion and metastasis. Exhausting lactate in tumors holds great promise for the reversal of the immunosuppressive tumor microenvironment (TME). Herein, we report on a “lactate treatment plant” (i.e., nanofactory) that can dynamically trap pro-tumor lactate and in situ transformation into anti-tumor cytotoxic reactive oxygen species (ROS) for a synergistic chemodynamic and metabolic therapy. To this end, lactate oxidase (LOX) was nano-packaged by cationic polyethyleneimine (PEI), assisted by a necessary amount of copper ions (PLNP^Cu). As a reservoir of LOX, the tailored system can actively trap lactate through the cationic PEI component to promote lactate degradation by two-fold efficiency. More importantly, the byproducts of lactate degradation, hydrogen peroxide (H₂O₂), can be transformed into anti-tumor ROS catalyzing by copper ions, mediating an immunogenic cell death (ICD). With the remission of immunosuppressive TME, ICD process effectively initiated the positive immune response in 4T1 tumor model (88% tumor inhibition). This work provides a novel strategy that rationally integrates metabolic therapy and chemodynamic therapy (CDT) for combating tumors.

Platelet Membranes Coated Gold Nanocages for Tumor Targeted Drug Delivery and Amplificated Low-Dose Radiotherapy

Continuous high doses of radiation can cause irreversible side effects and radiation resistance; thus, advanced radiosensitizers are urgently needed. To overcome this problem, we developed a nano platelet radiosensitization system (PCA) by coating the chemotherapeutic drug cisplatin (CDDP) loaded gold nanocages (AuNs) within the platelet membrane. The developed PCA system may enable AuNs to have immune escape and targeting capabilities. After administration, PCA will actively target tumor cells and avoid being cleared by the immune system. Subsequently, CDDP, which destroys tumor cell DNA, can not only kill tumor cells directly but also combine with AuNs, which deposit radiation energy into tumor tissues, reducing RT resistance. In vivo and in vitro studies revealed that the combination of PCA with RT (2Gy) efficiently inhibits tumor proliferation without causing side effects such as inflammation. To conclude, this is the first attempt to use platelet membranes to correctly transport AuNs while also accomplishing low-dose RT, which could help AuNs-based tumor RT become more effective.

Dual-Depletion of Intratumoral Lactate and ATP with Radicals Generation for Cascade Metabolic-Chemodynamic Therapy

Increasing evidence has demonstrated that lactate and adenosine triphosphate (ATP) both play important roles in regulating abnormal metabolism in the tumor microenvironment. Herein, an O2 self-supplying catalytic nanoagent, based on tannic acid (TA)-Fe(III) coordination complexes-coated perfluorooctyl bromide (PFOB) nanodroplets with lactate oxidases (LOX) loading (PFOB@TA-Fe(III)-LOX, PTFL), is designed for cascade metabolic-chemodynamic therapy (CDT) by dual-depletion of lactate and ATP with hydroxyl • OH radicals generation. Benefiting from the catalytic property of loaded LOX and O2 self-supplying of PFOB nanodroplets, PTFL nanoparticles (NPs) efficiently deplete tumoral lactate for down-regulation of vascular endothelial growth factor expression and supplement the insufficient endogenous H2 O2 . Simultaneously, TA-Fe(III) complexes release Fe(III) ions and TA in response to intracellular up-regulated ATP in tumor cells followed by TA-mediated Fe(III)/Fe(II) conversion, leading to the depletion of energy source ATP and the generation of cytotoxic • OH radicals from H2 O2 . Moreover, TA-Fe(III) complexes provide photoacoustic contrast as imaging guidance to enhance therapeutic accuracy. As a result, PTFL NPs efficiently accumulate in tumors for suppression of tumor growth and show evidence of anti-angiogenesis and anti-metastasis effects. This multifunctional nanoagent may provide new insight for targeting abnormal tumor metabolism with the combination of CDT to achieve a synergistic therapeutic effect.

Engineered Cell Membrane-Derived Nanoparticles in Immune Modulation

Immune modulation is one of the most effective approaches in the therapy of complex diseases, including public health emergency. However, most immune therapeutics such as drugs, vaccines, and cellular therapy suffer from the limitations of poor efficacy and adverse side effects. Fortunately, cell membrane-derived nanoparticles (CMDNs) have superior compatibility with other therapeutics and offer new opportunities to push the limits of current treatments in immune modulation. As the interface between cells and outer surroundings, cell membrane contains components which instruct intercellular communication and the plasticity of cytomembrane has significantly potentiated CMDNs to leverage our immune system. Therefore, cell membranes employed in immunomodulatory CMDNs have gradually shifted from natural to engineered. In this review, unique properties of immunomodulatory CMDNs and engineering strategies of emerging CMDNs for immune modulation, with an emphasis on the design logic are summarized. Further, this review points out some pressing problems to be solved during clinical translation and put forward some suggestions on the prospect of immunoregulatory CMDNs. It is anticipated that this review can provide new insights on the design of immunoregulatory CMDNs and expand their potentiation in the precise control of the dysregulated immune system.

pH-Regulating Nanoplatform for the "Double Channel Chase " of Tumor Cells by the Synergistic Cascade between Chlorine Treatment and Methionine-Depletion Starvation Therapy

During rapid proliferation and metabolism, tumor cells show a high dependence on methionine. The deficiency of methionine exhibits significant inhibition on tumor growth, which provides a potential therapeutic target in tumor therapy. Herein, ClO₂-loaded nanoparticles (fluvastatin sodium&metformin&bupivacaine&ClO₂@CaSiO₃@MnO₂-arginine-glycine-aspatic acid (RGD) (MFBC@CMR) NPs) were prepared for synergistic chlorine treatment and methionine-depletion starvation therapy. After outer layer MnO₂ was degraded in the high glutathione (GSH) tumor microenvironment (TME), MFBC@CMR NPs released metformin (Me) to target the mitochondria, thus interfering with the tricarboxylic acid (TCA) cycle and promoting the production of lactate. In addition, released fluvastatin sodium (Flu) by the NPs acted on monocarboxylic acid transporter 4 (MCT4) in the cell membrane to inhibit lactate leakage and induce a decrease of intracellular pH, further prompting the NPs to release chlorine dioxide (ClO₂), which then oxidized methionine, inhibited tumor growth, and produced large numbers of Cl^- in the cytoplasm. Cl^- could enter mitochondria through the voltage-dependent anion channel (VDAC) channel, which was opened by bupivacaine (Bup). The disruption of Cl^- homeostasis promotes mitochondrial damage and membrane potential decline, leading to the release of cytochrome C (Cyt-C) and apoptosis inducing factor (AIF) and further inducing cell apoptosis. To sum up, the pH-regulating and ClO₂-loaded MFBC@CMR nanoplatform can achieve cascade chlorine treatment and methionine-depletion starvation therapy toward tumor cells, which is of great significance for improving the clinical tumor treatment effect.

Activatable Biomineralized Nanoplatform Remodels the Intracellular Environment of Multidrug-Resistant Tumors for Enhanced Ferroptosis/Apoptosis Therapy

Ferroptosis is a new form of regulated cell death with significant therapeutic prospect, but its application against drug-resistant tumor cells is challenging due to their ability to effuse antitumor agents via p-glycoprotein (P-gp) and anti-lipid peroxidation alkaline intracellular environment. Herein, an amorphous calcium phosphate (ACP)-based nanoplatform is reported for the targeted combinational ferroptosis/apoptosis therapy of drug resistant tumor cells by blocking the MCT4-mediated efflux of lactic acid (LA). The nanoplatform is fabricated through the biomineralization of doxorubicin-Fe²⁺ (DOX-Fe²⁺ ) complex and MCT4-inhibiting siRNAs (siMCT4) and can release them to the tumor cytoplasm after the hydrolysis of ACP and dissociation of DOX-Fe²⁺ in the acidic lysosomes. siMCT4 can inhibit MCT4 expression and force the glycolysis-generated lactic acid (LA) to remain in cytoplasm for rapid acidification. The nanoplatform-induced remodeling of the tumor intracellular environment can not only interrupt the ATP supply required for P-gp-dependent DOX effusion to enhance H₂ O₂ production, but also increase the overall catalytic efficiency of Fe²⁺ for the initiation and propagation of lipid peroxidation. These features could act in concert to enhance the efficacy of the combinational ferroptosis/chemotherapy and prolong the survival of tumor-bearing mice. This study may provide new avenues for the treatment of multidrug-resistant tumors.

Metal-Phenolic Network-Enabled Lactic Acid Consumption Reverses Immunosuppressive Tumor Microenvironment for Sonodynamic Therapy

Nanomedicine has revolutionized cancer therapeutic strategies but has not completely changed the outcomes of tricky tumors that evolve a sophisticated immunosuppressive tumor microenvironment (TME) such as acidification. Here, a metal-phenolic network-based nanocomplex embedded with lactate oxidase (LOX) and a mitochondrial respiration inhibitor atovaquone (ATO) was constructed for immunosuppressive TME remodeling and sonodynamic therapy (SDT). In this nanocomplex, the sonosensitizer chlorin e6-conjugated polyphenol derivative can induce the generation of tumor lethal reactive oxygen species upon ultrasound irradiation. LOX served as a catalyst for intracellular lactic acid exhaustion, and ATO led to mitochondrial dysfunction to decrease oxygen consumption. This nanocomplex reversed the tumor immunosuppressive status by alleviating tumor hypoxia and acidic TME, achieving the characteristic enhancement of SDT and the inhibition of tumor proliferation and metastasis.

Fenton/Fenton-like metal-based nanomaterials combine with oxidase for synergistic tumor therapy

Chemodynamic therapy (CDT) catalyzed by transition metal and starvation therapy catalyzed by intracellular metabolite oxidases are both classic tumor treatments based on nanocatalysts. CDT monotherapy has limitations including low catalytic efficiency of metal ions and insufficient endogenous hydrogen peroxide (H₂O₂). Also, single starvation therapy shows limited ability on resisting tumors. The “metal-oxidase” cascade catalytic system is to introduce intracellular metabolite oxidases into the metal-based nanoplatform, which perfectly solves the shortcomings of the above-mentioned monotherapiesIn this system, oxidases can not only consume tumor nutrients to produce a “starvation effect”, but also provide CDT with sufficient H₂O₂ and a suitable acidic environment, which further promote synergy between CDT and starvation therapy, leading to enhanced antitumor effects. More importantly, the “metal-oxidase” system can be combined with other antitumor therapies (such as photothermal therapy, hypoxia-activated drug therapy, chemotherapy, and immunotherapy) to maximize their antitumor effects. In addition, both metal-based nanoparticles and oxidases can activate tumor immunity through multiple pathways, so the combination of the “metal-oxidase” system with immunotherapy has a powerful synergistic effect. This article firstly introduced the metals which induce CDT and the oxidases which induce starvation therapy and then described the “metal-oxidase” cascade catalytic system in detail. Moreover, we highlight the application of the “metal-oxidase” system in combination with numerous antitumor therapies, especially in combination with immunotherapy, expecting to provide new ideas for tumor treatment.

Advanced Cancer Starvation Therapy by Simultaneous Deprivation of Lactate and Glucose Using a MOF Nanoplatform

Recent investigations reveal that lactate is not a waste product but a major energy source for cells, especially in the mitochondria, which can support cellular survival under glucose shortage. Accordingly, the new understanding of lactate prompts to target it together with glucose to pursue a more efficient cancer starvation therapy. Herein, zeolitic imidazolate framework-8 (ZIF-8) nanoplatforms are used to co-deliver α-cyano-4-hydroxycinnamate (CHC) and glucose oxidase (GOx) and fulfill the task of simultaneous depriving of lactate and glucose, resulting in a new nanomedicine CHC/GOx@ZIF-8. The synthesis conditions are carefully optimized in order to yield monodisperse and uniform nanomedicines, which will ensure reliable and steady therapeutic properties. Compared with the strategies aiming at a single carbon source, improved starvation therapy efficacy is observed. Besides, more than boosting the energy shortage, CHC/GOx@ZIF-8 can block the lactate-fueled respiration and relieve solid tumor hypoxia, which will enhance GOx catalysis activity, depleting extra glucose, and producing more cytotoxic H2 O2 . By the synergistically enhanced anti-tumor effect, both in vitro and in vivo cancer-killing efficacies of CHC/GOx@ZIF-8 show twice enhancements than the GOx mediated therapy. The results demonstrate that the dual-depriving of lactate and glucose is a more advanced strategy for strengthening cancer starvation therapy.

A Versatile Nanoplatform for Broad-Spectrum Immunotherapy by Reversing the Tumor Microenvironment

Immunotherapy is currently an important adjuvant therapy for malignant tumors besides surgical treatment. However, the heterogeneity and low immunogenicity of the tumor are two main challenges of the immunotherapy. Here, we have constructed a nanoplatform (CP@mRBC-PpIX) to realize reversion of the tumor acidosis and hypoxia through alkali and oxygen generation triggered by tumor acidosis. By targeting tumor universal features other than endogenous biomarkers, it was found that CP@mRBC-PpIX could polarize tumor-associated macrophages to anti-tumor M1 phenotype macrophages to enhance tumor immune response. Furthermore, under regional light irradiation, the reactive oxygen species produced by photosensitizers located in CP@mRBC-PpIX could increase the immunogenicity of tumors, so that tumor changes from an immunosuppressive "cold tumor" to an immunogenic "hot tumor," thereby increasing the infiltration and response of T cells, further amplifying the effect of immunotherapy. This strategy circumvented the problem of tumor heterogeneity to realize a kind of broad-spectrum immunotherapy, which could effectively prevent tumor metastasis and recurrence.

An Injectable Hydrogel for Enhanced FeGA-Based Chemodynamic Therapy by Increasing Intracellular Acidity

Hydroxyl radical (•OH)-mediated chemodynamic therapy (CDT) is an emerging antitumor strategy, however, acid deficiency in the tumor microenvironment (TME) hampers its efficacy. In this study, a new injectable hydrogel was developed as an acid-enhanced CDT system (AES) for improving tumor therapy. The AES contains iron-gallic acid nanoparticles (FeGA) and α-cyano-4-hydroxycinnamic acid (α-CHCA). FeGA converts near-infrared laser into heat, which results in agarose degradation and consequent α-CHCA release. Then, as a monocarboxylic acid transporter inhibitor, α-CHCA can raise the acidity in TME, thus contributing to an increase in ·OH-production in FeGA-based CDT. This approach was found effective for killing tumor cells both in vitro and in vivo, demonstrating good therapeutic efficacy. In vivo investigations also revealed that AES had outstanding biocompatibility and stability. This is the first study to improve FeGA-based CDT by increasing intracellular acidity. The AES system developed here opens new opportunities for effective tumor treatment.

Reinforcing the Induction of Immunogenic Cell Death Via Artificial Engineered Cascade Bioreactor-Enhanced Chemo-Immunotherapy for Optimizing Cancer Immunotherapy

Traditional chemo-immunotherapy can elicit T cell immune response by inducing immunogenic cell death (ICD), however, insufficient ICD limits the lasting antitumor immunotherapeutic efficacy. Herein, tadpole-ovoid manganese-doped hollow mesoporous silica coated gold nanoparticles (Au@HMnMSNs) as biodegradable catalytic cascade nanoreactors are constructed to generate intratumoral high-toxic hydroxyl radicals combined with DOX and Aspirin (ASA) for enhancing the induction of ICD and maturation of dendritic cells (DCs). The released Mn²⁺ can catalyze endogenous H₂ O₂ to hydroxyl radicals, while internal gold nanoparticles mimetic glucose oxidase (GOx) converted glucose into H₂ O₂ to accelerate the generation of hydroxyl radicals. On the other hand, tadpole oval-structured Au@HMnMSNs can avoid the inactivation of gold nanoparticles due to strong protein adsorption. The introduction of ASA is to recruit DCs and cytotoxic T lymphocytes (CTLs) to tumor sites and restrain the intratumoral infiltration of immunosuppressive cells by decreasing the expression of prostaglandin E2 (PGE₂ ). Accordingly, this work presents a novel insight to introduce GOx-like catalytic cascade ICD nano-inducer into antitumor immunotherapy for synergistic tumor therapy.

Recent Advances in Engineered Materials for Immunotherapy-Involved Combination Cancer Therapy

Immunotherapy that can activate immunity or enhance the immunogenicity of tumors has emerged as one of the most effective methods for cancer therapy. Nevertheless, single-mode immunotherapy is still confronted with several critical challenges, such as the low immune response, the low tumor infiltration, and the complex immunosuppression tumor microenvironment. Recently, the combination of immunotherapy with other therapeutic modalities has emerged as a powerful strategy to augment the therapeutic outcome in fighting against cancer. In this review, recent research advances of the combination of immunotherapy with chemotherapy, phototherapy, radiotherapy, sonodynamic therapy, metabolic therapy, and microwave thermotherapy are summarized. Critical challenges and future research direction of immunotherapy-based cancer therapeutic strategy are also discussed.

Lactic acid in macrophage polarization: The significant role in inflammation and cancer

Metabolite lactic acid has always been regarded as a metabolic by-product rather than a bioactive molecule. Recently, this view has changed since it was discovered that lactic acid can be used as a signal molecule and has novel signal transduction functions both intracellular and extracellular, which can regulate key functions in the immune system. In recent years, more and more evidence has shown that lactic acid is closely related to the metabolism and polarization of macrophages. During inflammation, lactic acid is a regulator of macrophage metabolism, and it can prevent excessive inflammatory responses; In malignant tumors, lactic acid produced by tumor tissues promotes the polarization of tumor-associated macrophages, which in turn promotes tumor progression. In this review, we examined the relationship between lactic acid and macrophage metabolism. We further discussed how lactic acid plays a role in maintaining the homeostasis of macrophages, as well as the biology of macrophage polarization and the M1/M2 imbalance in human diseases. Potential methods to target lactic acid in the treatment of inflammation and cancer will also be discussed so as to provide new strategies for the treatment of diseases.

Manganese oxide nanomaterials boost cancer immunotherapy

Immunotherapy, a strategy that leverages the host immune function to fight against cancer, plays an increasingly important role in clinical tumor therapy. In spite of the great success achieved in not only clinical treatment but also basic research, cancer immunotherapy still faces many huge challenges. Manganese oxide nanomaterials (MONs), as ideal tumor microenvironment (TME)-responsive biomaterials, are able to dramatically elicit anti-tumor immune responses in multiple ways, indicating great prospects for immunotherapy. In this review, on the basis of different mechanisms to boost immunotherapy, major highlighted topics are presented, covering adjusting an immunosuppressive TME by generating O2 (like O2-sensitized photodynamic therapy (PDT), programmed cell death ligand-1 (PD-L1) expression downregulation, reprogramming tumor-associated macrophages (TAMs), and restraining tumor angiogenesis and lactic acid exhaustion), inducing immunogenic cell death (ICD), photothermal therapy (PTT) induction, activating the stimulator of interferon gene (STING) pathway and immunoadjuvants for nanovaccines. We hope that this review will provide holistic understanding about MONs and their application in cancer immunotherapy, and thus pave the way to the translation from bench to bedside in the future.

Zwitterion-Based Hydrogen Sulfide Nanomotors Induce Multiple Acidosis in Tumor Cells by Destroying Tumor Metabolic Symbiosis

Destruction of tumor metabolism symbiosis is an attractive cancer treatment method which targets tumor cells with little harm to normal cells. Yet, a single intervention strategy and poor penetration of the drug in tumor tissue result in limited effect. Herein, we propose a zero-waste zwitterion-based hydrogen sulfide (H2 S)-driven nanomotor based on the basic principle of reaction in human body. When loaded with monocarboxylic acid transporter inhibitor α-cyano-4-hydroxycinnamic acid (α-CHCA), the nanomotor can move in tumor microenvironment and induce multiple acidosis of tumor cells and inhibit tumor growth through the synergistic effect of motion effect, driving force H2 S and α-CHCA. Given the good biosafety of the substrate and driving gas of this kind of nanomotor, as well as the limited variety of nanomotors currently available to move in the tumor microenvironment, this kind of nanomotor may provide a competitive candidate for the active drug delivery system of cancer treatment.

Hollow structures as drug carriers: Recognition, response, and release

Hollow structures have demonstrated great potential in drug delivery owing to their privileged structure, such as high surface-to-volume ratio, low density, large cavities, and hierarchical pores. In this review, we provide a comprehensive overview of hollow structured materials applied in targeting recognition, smart response, and drug release, and we have addressed the possible chemical factors and reactions in these three processes. The advantages of hollow nanostructures are summarized as follows: hollow cavity contributes to large loading capacity; a tailored structure helps controllable drug release; variable compounds adapt to flexible application; surface modification facilitates smart responsive release. Especially, because the multiple physical barriers and chemical interactions can be induced by multishells, hollow multishelled structure is considered as a promising material with unique loading and releasing properties. Finally, we conclude this review with some perspectives on the future research and development of the hollow structures as drug carriers.

C. tropicalis promotes chemotherapy resistance in colon cancer through increasing lactate production to regulate the mismatch repair system

Due to chemotherapeutic drug resistance, tumor recurrence is common in patients with colorectal cancer (CRC) and chemo-resistant patients are often accompanied by defects in the mismatch repair system (MMR). Our previous study has shown that Candida tropicalis (C. tropicalis) is closely related to the occurrence and development of colorectal cancer, but whether this conditional pathogenic fungus is involved in chemotherapy needs further investigation. Here we found that C. tropicalis promoted chemotherapy resistance of colon cancer to oxaliplatin. Compared with oxaliplatin-treated group, the expression of functional MMR proteins in tumors were decreased in C.tropicalis/oxaliplatin -treated group, while the glycolysis level of tumors was up-regulated and the production of lactate was significantly increased in C.tropicalis/oxaliplatin -treated group. Inhibiting lactate production significantly alleviated the chemoresistance and rescued the decreased expression of MMR caused by C. tropicalis. Furthermore, we found that lactate down-regulated the expression of MLH1 through the GPR81-cAMP-PKA-CREB axis. This study clarified that C. tropicalis promoted chemoresistance of colon cancer via producing lactate and inhibiting the expression of MLH1, which may provide novel ideas for improving CRC chemotherapy effect.

Transformable Spinose Nanodrums with Self-Supplied H2 O2 for Photothermal and Cascade Catalytic Therapy of Tumor

Advances in enzymes involve an efficient biocatalytic process, which has demonstrated great potential in biomedical applications. However, designing a functional carrier for enzymes equipped with satisfactory degradability and loading efficiency, remains a challenge. Here, based on transformable liquid metal (LM), a spinose nanodrum is designed as protein carrier to deliver enzyme for tumor treatment. With the assistance of spines and a special drum-like shape, it is found that the spiny LM can carry much more enzymes than spherical LM under the same condition. Benefiting from the satisfactory enzyme loading efficiency of spiny LM, a plasma amine oxidase immobilized spinose LM nanosystem enveloped with epigallocatechin gallate (EGCG)-Fe³⁺ (LMPE) is fabricated for photothermal and cascade catalytic tumor therapy. Activated by the acidic condition in the tumor microenvironment, the LMPE can oxidize spermine (Spm) and spermidine (Spd) to generate hydrogen peroxide (H₂ O₂ ) for Fenton catalytic reaction to produce the lethal hydroxyl radical (•OH) for tumor cell killing. Combined with remarkable photothermal performance of LM, LMPE exhibits significant inhibition of tumor in vivo.

Multifunctional Nanodrug Mediates Synergistic Photodynamic Therapy and MDSCs-Targeting Immunotherapy of Colon Cancer

An ideal tumor treatment is supposed to eliminate the primary tumor and simultaneously trigger the host antitumor immune responses to prevent tumor recurrence and metastasis. Herein, a liposome encapsulating phosphoinositide 3-kinase gamma (PI3Kγ) inhibitor IPI-549 and photosensitizer chlorin e6 (Ce6), denoted by LIC, is prepared for colon cancer treatment. LIC internalized into CT26 cells generates reactive oxygen species (ROS) under laser irradiation to cause immunogenic tumor cell death, during which immunostimulatory signals such as calreticulin are released to further induce T lymphocyte-mediated tumor cell killing. Meanwhile, IPI-549 transported by liposome can inhibit PI3Kγ in the myeloid-derived suppressive cells (MDSCs), resulting in downregulation of arginase 1 (Arg-1) and ROS to promote MDSCs apoptosis and reduce their immunosuppressive activity to CD8⁺ T cells. LIC-mediated immunogenic photodynamic therapy synergizes with MDSCs-targeting immunotherapy, which significantly inhibits tumor growth via facilitating the dendritic cell maturation and tumor infiltration of CD8⁺ T cells while decreasing the tumor infiltration of immunosuppressive regulatory T cells, MDSCs, and M2-like tumor-associated macrophages. Moreover, the synergistic therapy increases the number of effector memory T cells (T_EM ) in spleen, which suggests a favorable immune memory to prevent tumor recurrence and metastasis. The Ce6 and IPI-549-coloaded multifunctional nanodrug demonstrates high efficacy in colon cancer treatment.

A biomimetic nanozyme/camptothecin hybrid system for synergistically enhanced radiotherapy

Although radiotherapy (RT) has been an effective therapeutic regimen against most solid tumors, its effect is limited by the hypoxic tumor microenvironment and radio-tolerance of tumor cells to a large extent. Here we have designed a biomimetic nanozyme/camptothecin hybrid system for synergistically enhanced radiotherapy, which consists of an internal camptothecin (CPT)-loaded hollow MnO2 core and an external tumor cell membrane. The tumor cell membrane endows the system with excellent tumor targeting ability. The hollow MnO2 core can deliver the hydrophobic drug CPT and catalyze the production of oxygen from hydrogen peroxide in tumor tissues, which was finally degraded into Mn2+, a T1-weighted contrast agent. The anti-tumor mechanism of this system includes two aspects: (i) the generated oxygen can improve the hypoxic state of the tumor microenvironment and enhance the radiotherapy sensitivity and (ii) CPT can induce cell cycle arrest in the S-phase at a low dose, which further increases the radio-sensitivity of tumor cells and augmented radiation-induced tumor damage. The results of in vivo experiments showed that the biomimetic nanozyme drug delivery system improved the hypoxic microenvironment of the tumor tissue with a high tumor inhibition rate in a murine model. This platform achieved synergistic radiotherapy sensitization and provided a novel idea for the design of a radiotherapy sensitization system.

Self-Assembled Hybrid Nanogel as a Multifunctional Theranostic Probe for Enzyme-Regulated Ultrasound Imaging and Tumor Therapy

Multifunctional theranostic nanoprobes integrated with stimuli-responsive imaging and therapeutic capabilities have shown great potential to enhance the early cancer diagnostic efficacy and therapeutic efficiency. Elevated levels of lactate and hydrogen peroxide have been considered as the characteristic feature of the tumor microenvironment and can thus be exploited for developing promising theranostic strategies. We demonstrate here that the biocompatible and responsive enzyme-based nanogel probe has been designed as a promising theranostic tool to target high lactate and hydrogen peroxide for ultrasound imaging (US) and cancer treatment. We encapsulate the dual enzyme lactate oxidase (LOD) and catalase (CAT) into the self-assembled nanogels to fabricate responsive nanoprobe LOD/CAT-loaded nanogels (LCNGs). The nanoprobes can respond to the lactate and H₂O₂ rich tumor microenvironment to generate abundant oxygen, which further accumulates into microbubbles for enhanced US imaging. Besides, LCNGs@DOX has been further created by integrating the nanoprobes with doxorubicin (DOX) for cancer therapy. Both in vitro and in vivo results demonstrate enhanced US imaging and effective cell proliferation inhibition of LCNGs@DOX, allowing the preparation of safe and efficient theranostic nanoprobes capable of responsive US imaging and treating tumors.

Glycyrrhizic Acid Nanoparticles as Antiviral and Anti-inflammatory Agents for COVID-19 Treatment

COVID-19 has been diffusely pandemic around the world, characterized by massive morbidity and mortality. One of the remarkable threats associated with mortality may be the uncontrolled inflammatory processes, which were induced by SARS-CoV-2 in infected patients. As there are no specific drugs, exploiting safe and effective treatment strategies is an instant requirement to dwindle viral damage and relieve extreme inflammation simultaneously. Here, highly biocompatible glycyrrhizic acid (GA) nanoparticles (GANPs) were synthesized based on GA. In vitro investigations revealed that GANPs inhibit the proliferation of the murine coronavirus MHV-A59 and reduce proinflammatory cytokine production caused by MHV-A59 or the N protein of SARS-CoV-2. In an MHV-A59-induced surrogate mouse model of COVID-19, GANPs specifically target areas with severe inflammation, such as the lungs, which appeared to improve the accumulation of GANPs and enhance the effectiveness of the treatment. Further, GANPs also exert antiviral and anti-inflammatory effects, relieving organ damage and conferring a significant survival advantage to infected mice. Such a novel therapeutic agent can be readily manufactured into feasible treatment for COVID-19.

Multifunctional MnO2 nanoparticles for tumor microenvironment modulation and cancer therapy

Tumor microenvironment (TME) is generally featured by low pH values, high glutathione (GSH) concentrations, overproduced hydrogen peroxide (H₂ O₂ ), and severe hypoxia. These characteristics could provide an interior environment for origination and residence of tumor cells and would lead to tumor progression, metastasis, and drug resistance. Therefore, the development of TME-responsive smart nanosystems has shown significant potential to enhance the efficacy of current cancer treatments. Manganese dioxide (MnO₂ )-based nanosystems have attracted growing attentions for applications in cancer treatment as an excellent TME-responsive theranostic platform, due to their tunable structures/morphologies, pH responsive degradation, and excellent catalytic activities. In this review, we mainly summarize the strategies of MnO₂ and its nanocomposites to modulate TME, such as tumor hypoxia relief, excessive GSH depletion, glucose consumption, and tumor immunosuppressive microenvironment moderation. Such MnO₂ -based TME modulation would be beneficial for a wide range of cancer therapies including photodynamic therapy, radiotherapy, sonodynamic therapy, chemodynamic therapy, starvation therapy, and immunotherapy. Next, some representative designs of MnO₂ -based nanoplatforms in other tumor therapies are highlighted. Moreover, we will discuss the challenges and future perspectives of these MnO₂ -based nanosystems for enhanced tumor treatment. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease.

Patient-derived microvesicles/AIE luminogen hybrid system for personalized sonodynamic cancer therapy in patient-derived xenograft models

Sonodynamic therapy (SDT), as an efficient way of tumor treatment, has the advantages of deep tumor penetration and high therapeutic efficacy. However, developing efficient sonosensitizers are still challenging. AIEgen-based SDT is rarely reported and it is urgent to develop novel AIEgen-active sonosensitizers. Furthermore, the AIEgen-based theranostic system is promisingly needed to be proved on PDX models to be closer to the clinic. Herein, we constructed a novel AIEgen based SDT system and found that DCPy has advantages over traditional sonosensitizers in SDT. Then, a patient-derived MVs/AIEgen hybrid system (AMVs) prepared by electroporation was used for personalized SDT in bladder cancer patient-derived xenograft (PDX) models. Impressively, AMVs displayed the superior tumor targeting ability and efficient personalized SDT therapy on PDX models, both of which were much more improved compared with PLGA/AIEgens nanoparticles and cell line-derived micro vesicles. This work provides new ideas for both the design of AIE-active sonosensitizers and the SDT treatment of cancers, further expanding the potential clinical application of AIEgens in the future.

Functionalized nanoprobes for in situ detection of telomerase

Telomerase, a special ribonucleoprotein reverse transcriptase, can maintain the length and stability of telomeres and plays an important role in cell proliferation and differentiation. Due to the distinguishable expression level in normal cells and cancer cells, telomerase has become an important biomarker for cancer diagnosis and prognosis evaluation. Despite major breakthroughs in the field of telomerase detection, the extracts in the cell lysate are still the first choice as the analyte nevertheless, which will bring serious inaccuracies compared with the real intracellular activity. With the development of nanotechnology and nanomaterials, extraordinary progress has been made in telomerase detection by employing different versatile nanoprobes. In this review, we list the superiority of nanoprobes and systematically summarize the applications of nanoprobes in telomerase detection from the aspects of various nanomaterials and discuss the current challenges and potential trends in the future design of nanoprobes.

Tumor acidic microenvironment-induced drug release of RGD peptide nanoparticles for cellular uptake and cancer therapy

Spatial accuracy is crucial in drug delivery, especially to increase the efficacy and reduce the side effects of antitumor drugs. In this study, we developed a simple and broadly applicable strategy in which a target peptide ligand was introduced to construct a pH-responsive drug-loading system to achieve targeted delivery and drug release in lesions. In addition to reaching the tumor tissue through passive targeting modalities such as the enhanced permeability and retention (EPR) effect, active targeting nanoparticles used RGD motifs coupled to nanocarriers to specifically bind certain integrins, such as ανβ3, which is expressed on the surface of tumor cells, to achieve active tumor cell targeting. Self-assembling peptides have significant advantages in their structural design. The amphiphilic peptide LKR could form a spherical and self-assembled nanoparticle, which encapsulated the fat-soluble antitumor drug doxorubicin (Dox) in neutral medium. The Dox-encapsulating peptide nanoparticles swelled and burst, rapidly releasing Dox in an acidic microenvironment. Flow cytometry and fluorescence detection showed that the self-assembled LKR nanoparticles enhanced the drug accumulation in tumor cells compared with normal mammalian cells. The Dox-encapsulating peptide nanoparticles exhibited desirable antitumor effects in vivo. In summary, the acidic microenvironment of tumors was used to induce drug release from a targeted peptide drug-loading system to enhance cellular uptake and therapeutic effects in situ, providing a promising therapeutic approach for the treatment of major diseases such as hepatoma.

Nanomedicine-based cancer immunotherapies developed by reprogramming tumor-associated macrophages

Tumor microenvironment is a complex ecosystem composed of tumor extracellular matrix, fibroblasts, blood vessels, and immune cells, promoting tumor development by secreting various growth factors, hydrolase, and inflammatory factors. Tumor-associated macrophages (TAMs) constitute the largest number of immune cells in the TME, and they have a "double-edged sword" effect on tumor growth, invasion, metastasis, angiogenesis, and immunosuppression. Under the regulation of different cytokines in the TME, the bidirectional TAMs can switch their phenotypes between tumoricidal M1-like and pro-tumorigenic M2-like macrophages. TAM polarization suggests that scientists can use this property to design drugs targeting this regulation as a promising immunotherapy strategy to enhance tumor therapy efficiency. In this review, we summarize a brief introduction of TAMs and their implications for tumorigenesis. Next, we review recent advances in designing various functionalized nanomedicines and their applications in nanomedicine-based cancer therapies that target TAMs by killing them, inhibiting macrophage recruitment, and repolarizing them from pro-tumorigenic M2-like to tumoricidal M1-like macrophages. Simultaneously, the regulation of nanomedicines on the signaling pathways accounting for these effects is also summarized. This review will not only provide background scientific information for the understanding of TAMs and their roles in cancer treatment but also help scientists design nanomedicines based on tumor TAMs, which can help achieve better clinical treatment outcomes for tumors.

Lactate-induced M2 polarization of tumor-associated macrophages promotes the invasion of pituitary adenoma by secreting CCL17

Background: Lactate greatly contributes to the regulation of intracellular communication within the tumor microenvironment (TME). However, the role of lactate in pituitary adenoma (PA) invasion is unclear. In this study, we aimed to clarify the effects of lactate on the TME and the effects of TME on PA invasion.

Methods: To explore the correlation between TME acidosis and tumor invasion, LDHA and LAMP2 expression levels were quantified in invasive (n = 32) and noninvasive (n = 32) PA samples. The correlation between immune cell infiltration and tumor invasion was evaluated in 64 PAs. Critical chemokine and key signaling pathway components were detected by qPCR, Western blotting, siRNA knockdown, and specific inhibitors. The functional consequences of CCR4 signaling inhibition were evaluated in vitro and in vivo.

Results: Lactate was positively associated with PA invasion. Of the 64 PA tissues, invasive PAs were related to high infiltration of M2-like tumor-associated macrophages (TAMs) (P < 0.05). Moreover, lactate secreted from PA cells facilitated M2 polarization via the mTORC2 and ERK signaling pathways, while activated TAMs secreted CCL17 to promote PA invasion via the CCL17/CCR4/mTORC1 axis. According to univariate analysis of clinical data, high CCL17 expression was associated with larger tumor size (P = 0.0438), greater invasion (P = 0.0334), and higher susceptibility to postoperative recurrence (P = 0.0195) in human PAs.

Conclusion: This study illustrates the dynamics between PA cells and immune TME in promoting PA invasion via M2 polarization. CCL17 levels in the TME are related to the PA invasiveness and clinical prognosis, and the CCL17/CCR4/mTOCR1 axis may serve as potential therapeutic targets for Pas.

Regulating glucose metabolism using nanomedicines for cancer therapy

The regulation of glucose metabolism is a research focus in cancer treatment. Glucose metabolism is essential for maintaining the growth and proliferation of tumor cells, thus offering us great opportunities for tumor treatment. Recently, much progress has been made in efficient cancer treatment by regulating the pathway of glucose metabolism with nanomedicines due to the rapid development of nanotechnology and promising drug targets. In this review, we first introduced the pathway of cell energy supply from the perspective of aerobic and anaerobic processes. Then, we discussed the recent research progress in regulating glucose metabolism for various tumor resistance strategies including heat resistance, multiple drug resistance, and hypoxia. Finally, we presented the prospects and challenges of developing multifunctional nanoagents for efficient chemotherapy, hyperthermia, dynamic therapy and so on by regulating glucose metabolism.

Aptamer-Functionalized Dendrimer Delivery of Plasmid-Encoding lncRNA MEG3 Enhances Gene Therapy in Castration-Resistant Prostate Cancer

Purpose

The clinical management of patients with castration-resistant prostate cancer (CRPC) is difficult. However, novel treatment methods are gradually being introduced. Considering the adverse effects of traditional treatments, recent studies have investigated gene therapy as a method to combat CRPC; but, the application of long non-coding (lnc) RNA in gene therapy remains scarce, despite their promise. Therefore, it is imperative to develop a system that can efficiently deliver lncRNA for the treatment of CRPC. Here, we investigated the efficacy of a delivery system by introducing the plasmid-encoding tumor suppressor lncRNA MEG3 (pMEG3) in CRPC cells.

Materials and Methods

An EpDT3 aptamer-linked poly(amidoamine) (PAMAM) dendrimer targeting EpCAM was used to deliver pMEG3 in CRPC cells. The PAMAM-PEG-EpDT3/pMEG3 nanoparticles (NPs) were tested using in vitro cellular assays including cellular uptake, entry, and CCK-8 measurement, and tumor growth inhibition, histological assessment, and safety evaluations in in vivo animal models.

Results

The EpDT3 aptamer promoted endocytosis of PAMAM and PAMAM-PEG-EpDT3/pMEG3 NPs in CRPC cells. PAMAM-PEG-EpDT3/pMEG3 NPs exhibited a significant anti-CRPC effect, both in vivo and in vitro, when compared to that of unfunctionalized PAMAM-PEG/pMEG3 NPs.

Conclusion

PAMAM-PEG-EpDT3/pMEG3 NPs can potentially improve gene therapy in CRPC cells.

Thrombospondin 2/Toll-Like Receptor 4 Axis Contributes to HIF-1α-Derived Glycolysis in Colorectal Cancer

Background

Aerobic glycolysis is a typical metabolic reprogramming in tumor cells, which contributes to the survival and proliferation of tumor cells. The underlying mechanisms controlling this metabolic switch in colorectal cancer (CRC), however, remain only partially understood.

Methods

The Cancer Genome Atlas (TCGA) dataset and Gene Expression Omnibus (GEO) (GDS4382, GSE6988, GSE35834) were used to analyzed the mRNA expression of THBS2. 392 paired samples of CRC and adjacent non-cancerous tissues were collected to detect the expression of THBS2 by IHC. The correlation of THBS2 expression with categorical clinical variables in patients with CRC was evaluated using chi-square analysis or Student's t-test. CCK-8, colony formation, and animal CT scan were used to functional analysis of THBS2 in CRC.

Results

Thrombospondin 2 (THBS2) is aberrantly upregulated and linked to a poor prognosis in CRC. Subsequent experiments also showed that THBS2 promotes the proliferation of CRC cells. In terms of mechanism, THBS2 interacted with Toll-like receptor 4 (TLR4), but not with the other toll-like receptors (TLRs), which upregulated the mRNA expression of GLUT1, HK2, ALDOA, PKM2, and LDHA and enhanced glycolytic capacity in CRC cells. Moreover, THBS2/TLR4 axis significantly increased the protein level of HIF-1α and blocking HIF-1α by siRNA reversed the enhanced glycolytic capacity and the upregulated expression of glycolytic enzymes in CRC cells.

Conclusion

Our findings revealed that the THBS2/TLR4 axis contributes to HIF-1α derived glycolysis and eventually promotes CRC progress.

A pH-Responsive Polymer-CeO2 Hybrid to Catalytically Generate Oxidative Stress for Tumor Therapy

Catalytic generation of reactive oxygen species has been developed as a promising methodology for tumor therapy. Direct O₂^•- production from intratumor oxygen exhibits exceptional tumor therapeutic efficacy. Herein, this therapy strategy is demonstrated by a pH-responsive hybrid of porous CeO₂ nanorods and sodium polystyrene sulfonate that delivers high oxidative activity for O₂^•- generation within acidic tumor microenvironments for chemodynamic therapy and only limited oxidative activity in neutral media to limit damage to healthy organs. The hydrated polymer-nanorod hybrids with large hydrodynamic diameters form nanoreactors that locally trap oxygen and biological substrates inside and improve the charge transfer between the catalysts and substrates in the tumor microenvironment, leading to enhanced catalytic O₂^•- production and consequent oxidation. Together with successful in vitro and in vivo experiments, these data show that the use of hybrids provides a compelling opportunity for the delivery selective chemodynamic tumor therapy.

Engineering of Cascade-Responsive Nanoplatform to Inhibit Lactate Efflux for Enhanced Tumor Chemo-Immunotherapy

As an increased product of high-rate aerobic glycolysis in tumors, lactate could regulate the immunosuppressive tumor microenvironment (TME). A PEG-CDM surface modified, GSH-dependent responsive hollow mesoporous organosilica nanoplatform loaded with hydroxycamptothecin (HCPT) and siMCT-4 was administrated for synergistic tumor chemo-immunotherapy. The nanoplatform cascaded responded to the weak acid TME and the high level of GSH in tumor cells. HCPT and siMCT-4 were continuously released from the nanoplatform for chemotherapy and inhibiting intracellular lactate efflux. The increased intracellular lactate and HCPT effectively induced tumor cell apoptosis. Moreover, the decreased extracellular lactate polarized tumor-associated macrophages (TAMs) phenotype from M2 type to M1 type and restored CD8⁺ T cell activity in vivo. The results demonstrated that the nanoplatform effectively removed the immunosuppressive TME, inhibited tumor growth, and suppressed lung metastasis of B16F10 cells and 4T1 cells via the combination of inhibiting lactate efflux and chemotherapy. Accordingly, it suggested a strategy to transform immunosuppressive tumors into "hot" tumors and inhibit the tumor growth with high efficiency in vivo.

Nanostructured manganese dioxide for anticancer applications: preparation, diagnosis, and therapy

Nanostructured manganese dioxide (MnO₂) has attracted extensive attention in the field of anticancer applications. As we all know, the tumor microenvironment is usually characterized by a high glutathione (GSH) concentration, overproduced hydrogen peroxide (H₂O₂), acidity, and hypoxia, which affect the efficacy of many traditional treatments such as chemotherapy, radiotherapy, and surgery. Fortunately, as one kind of redox-active nanomaterial, nanostructured MnO₂ has many excellent properties such as strong oxidation ability, excellent catalytic activity, and good biodegradability. It can be used effectively in diagnosis and treatment when it reacts with some harmful substances in the tumor site. It can not only enhance the therapeutic effect but also adjust the tumor microenvironment. Therefore, it is necessary to present the recent achievements and progression of nanostructured MnO₂ for anticancer applications, including preparation methods, diagnosis, and treatment. Special attention was paid to photodynamic therapy (PDT), bioimaging and cancer diagnosis (BCD), and drug delivery systems (DDS). This review is expected to provide helpful guidance on further research of nanostructured MnO₂ for anticancer applications.

Highly Enhanced Antitumor Immunity by a Three-Barreled Strategy of the l-Arginine-Promoted Nanovaccine and Gene-Mediated PD-L1 Blockade

Weak T cell responses and immune checkpoints within tumors could be two key factors for limiting antitumor efficacy in the field of cancer immunotherapy. Thus, the combined strategy of tumor vaccines and immune checkpoint blockade has been widely studied and expected to boost antitumor immune responses. Herein, we first developed a two-barreled strategy to combine the nanovaccine with a gene-mediated PD-L1 blockade. On the one hand, polyethyleneimine (PEI) worked as a vaccine carrier to codeliver the antigen ovalbumin (OVA) and the adjuvant unmethylated cytosine-phosphate-guanine (CpG) to formulate the PEI/OVA/CpG nanovaccine through electrostatic binding, which realized both dendritic cell activation and antigen cross-presentation enhancement. On the other hand, the PD-L1 silence gene was loaded by PEI to form PEI/pshPD-L1 complexes, which were further in situ shielded by aldehyde-modified polyethylene glycol (OHC-PEG-CHO) via pH-responsive Schiff base bonds. The formed pshPD-L1@NPs could decrease PD-L1 expression on the tumor cells. However, such a combined two-barreled strategy improved feebly for tumor inhibition in comparison with monotherapy, exhibiting the antagonistic effect, which might be due to the limited T cell response enhancement in the tumor microenvironment. To solve this problem, we have further developed a three-barreled strategy to combine oral administration of l-arginine, which worked as an amplifier to induce robust T cell response enhancement, without causing the upregulation of other negative immune regulators. Superior antitumor behavior and tumor rechallenge protection were realized by the three-barreled strategy in B16F10-OVA (B16-OVA)-bearing mice. The unique three-barreled strategy we developed might offer a novel clinical therapeutic treatment.

Click Reaction-Assisted Peptide Immune Checkpoint Blockade for Solid Tumor Treatment

One of the major challenges of immune checkpoint blockade (ICB) is the poor penetration of antibody for solid tumor treatment. Herein, peptides with deeper penetration capability are used to develop a click reaction-assisted peptide immune checkpoint blockade (CRICB) strategy that could in situ construct assemblies, enabling enhanced accumulation and prolonged PD-L1 occupancy, ultimately realizing high-performance tumor inhibition. First, the free DBCO-modified targeting peptide (TP) efficiently recognizes and binds PD-L1 in a deep solid tumor. Upon a reagent-free click reaction with a subsequently introduced azide-tethered assembled peptide (AP), the click reaction results in spontaneous self-aggregation in situ with enhanced accumulation and prolonged occupancy. In addition, the penetration of TP-AP (121.2 ± 15.5 μm) is significantly enhanced compared with that of an antibody (19.9 ± 5.6 μm) in a solid tumor tissue. More importantly, significant immunotherapy effects and negligible side effects are observed in 4T1 and CT26 tumor-bearing mice models treated with TP-AP, suggesting the high-performance tumor inhibition attributed to the CRICB strategy. In summary, this CRICB strategy manifest the preferable effects of immune checkpoint blockade, thereby extending the biomedical application of assembling peptides.

Chemistry of Advanced Nanomedicines in Cancer Cell Metabolism Regulation

Tumors reprogram their metabolic pathways to meet the bioenergetic and biosynthetic demands of cancer cells. These reprogrammed activities are now recognized as the hallmarks of cancer, which not only provide cancer cells with unrestricted proliferative and metastatic potentials, but also strengthen their resistance against stress conditions and therapeutic challenges. Although recent progress in nanomedicine has largely promoted the developments of various therapeutic modalities, such as photodynamic therapy, photothermal therapy, nanocatalytic therapy, tumor-starving/suffocating therapy, etc., the therapeutic efficacies of nanomedicines are still not high enough to achieve satisfactory tumor-suppressing effects. Therefore, researchers are obliged to look back to the essence of cancer cell biology, such as metabolism, for tailoring a proper therapeutic regimen. In this work, the characteristic metabolic pathways of cancer cells, such as aerobic respiration, glycolysis, autophagy, glutaminolysis, etc. are reviewed, to summarize the very recent advances in the smart design of nanomedicines that can regulate tumor metabolism for enhancing conventional therapeutic modalities. The underlying chemistry of these nanomedicines by which tumor metabolism is harnessed, is also discussed in a comprehensive manner. It is expected that by harnessing tumor metabolism cancer nanotherapeutics will be substantially improved in the future.

GSH depletion liposome adjuvant for augmenting the photothermal immunotherapy of breast cancer

The high redox level of tumor microenvironment inhibits the oxidation treatment and the immune response. Here, we innovatively develop maleimide liposome (ML) adjuvants to promote immunogenic cell death (ICD) induction and dendritic cells (DCs) maturation by glutathione (GSH) depletion for augmenting the photothermal immunotherapy of breast cancer. The ML effectively depletes the intracellular GSH and up-regulates reactive oxygen species (ROS) in both tumor cells and DCs. In tumor cells, the ROS boosted the ABTS·⁺ production to activate photothermal-induced ICD. In DCs, it relieved the immunosuppression, promoting DC maturation (57%) and antigen presenting. As a result of the ML assistant, the therapeutic systems improved the infiltration of CD8⁺ T cells to 53% in tumor tissues, eliciting strong abscopal effect and antimetastasis effect. The MLs were believed to be a superior candidate of adjuvants for enhancing immune response and cancer therapeutic efficacy.

Dual-Modal Therapeutic Role of the Lactate Oxidase-Embedded Hierarchical Porous Zeolitic Imidazolate Framework as a Nanocatalyst for Effective Tumor Suppression

The increasing evidence supports the fact that lactate in the tumor microenvironment (TME) plays a vital role in tumor proliferation, metastasis, and recurrence, which in turn is emerging as one of the most interesting molecular targets for tumor treatment. Here, hierarchical porous zeolitic imidazolate framework-8 (ZIF-8) as the nanocarrier is fabricated to simultaneously load lactate oxidase (LOD) and Fe₃O₄ nanoparticles (NPs), called LOD & Fe₃O₄@ZIF-8 NPs (LFZ NPs), for tumor therapy. On one hand, the sharp consumption of lactate in the TME by LOD will change the essential "soil" where tumor cells live so as to suppress tumor rapid growth. On the other hand, hydrogen peroxide (H₂O₂) is produced in the TME from the oxidation of lactate catalyzed by LOD and subsequently converted to highly toxic hydroxyl radicals (^•OH) catalyzed by Fe₃O₄ NPs via Fenton-like reactions to kill tumor cells. Based on the endogenous catalysis, this dual-modal strategy of tumor therapy based on lactate is simple, safe, and effective, which deserves to be well concerned.

Magnetic nanoparticles coated with polyphenols for spatio-temporally controlled cancer photothermal/immunotherapy

As the combination of photothermal therapy (PTT) with immunotherapy provides an effective strategy in cancer treatment, a magnetic nanoparticle delivery system was constructed to load indocyanine green (ICG) and immunostimulator R837 hydrochloride (R837) for spatio-temporally PTT/immunotherapy synergism in cancer. This delivery system is composed of Fe₃O₄ magnetic nanoparticles (MPs) as the core to load ICG and polyethylene glycol polyphenols (DPA-PEG) as the coating layer to load R837, which formed R837 loaded polyphenols coating ICG loaded magnetic nanoparticles (MIRDs). After intravenous injection, the formed MIRDs resulted in long circulation, magnetic resonance imaging (MRI) guides, and magnetic targeting. Once targeting to the tumor, the MIRDs with the near-infrared (NIR) irradiation caused tumor ablation and resulted in tumor-associated antigens releasing to induce the body's immunological response, which was markedly improved it to attack the tumors with the R837 releasing from the outer DPA-PEG. In this case, the synergism of the PTT and immunotherapy inhibited tumor growth, metastasis and recurrence, which resulted in potent anticancer therapeutic effects with few side effect.