Augmenting Tumor-Starvation Therapy by Cancer Cell Autophagy Inhibition

Ultrasound-Based Micro-/Nanosystems for Biomedical Applications

Due to the intrinsic non-invasive nature, cost-effectiveness, high safety, and real-time capabilities, besides diagnostic imaging, ultrasound as a typical mechanical wave has been extensively developed as a physical tool for versatile biomedical applications. Especially, the prosperity of nanotechnology and nanomedicine invigorates the landscape of ultrasound-based medicine. The unprecedented surge in research enthusiasm and dedicated efforts have led to a mass of multifunctional micro-/nanosystems being applied in ultrasound biomedicine, facilitating precise diagnosis, effective treatment, and personalized theranostics. The effective deployment of versatile ultrasound-based micro-/nanosystems in biomedical applications is rooted in a profound understanding of the relationship among composition, structure, property, bioactivity, application, and performance. In this comprehensive review, we elaborate on the general principles regarding the design, synthesis, functionalization, and optimization of ultrasound-based micro-/nanosystems for abundant biomedical applications. In particular, recent advancements in ultrasound-based micro-/nanosystems for diagnostic imaging are meticulously summarized. Furthermore, we systematically elucidate state-of-the-art studies concerning recent progress in ultrasound-based micro-/nanosystems for therapeutic applications targeting various pathological abnormalities including cancer, bacterial infection, brain diseases, cardiovascular diseases, and metabolic diseases. Finally, we conclude and provide an outlook on this research field with an in-depth discussion of the challenges faced and future developments for further extensive clinical translation and application.

Metal-Coordinated NIR-II Nanoadjuvants with Nanobody Conjugation for Potentiating Immunotherapy by Tumor Metabolism Reprogramming

Immune checkpoint blockade (ICB) immunotherapy remains hampered by insufficient immunogenicity and a high-lactate immunosuppressive tumor microenvironment (TME). Herein, a nanobody-engineered NIR-II nanoadjuvant with targeting metabolic reprogramming capability is constructed for potentiating NIR-II photothermal-ferroptosis immunotherapy. Specifically, the nanoadjuvant (2DG@FS-Nb) is prepared by metallic iron ion-mediated coordination self-assembly of D-A-D type NIR-II molecules and loading of glycolysis inhibitor, 2-deoxy-D-glucose (2DG), followed by modification with aPD-L1 nanobody (Nb), which can effectively target the immunosuppressive TME and trigger in situ immune checkpoint blockade. The nanoadjuvants responsively release therapeutic components in the acidic TME, enabling the precise tumor location by NIR-II fluorescence/photoacoustic imaging while initiating NIR-II photothermal-ferroptosis therapy. The remarkable NIR-II photothermal efficiency and elevated glutathione (GSH) depletion further sensitize ferroptosis to induce severe lipid peroxidation, provoking robust immunogenic cell death (ICD) to trigger anti-tumor immune response. Importantly, the released 2DG markedly inhibits lactate generation through glycolysis obstruction. Decreased lactate efflux remodels the immunosuppressive TME by suppressing M2 macrophage proliferation and downregulating regulatory T cell levels. This work provides a new paradigm for the integration of NIR-II phototheranostics and lactate metabolism regulation into a single nanoplatform for amplified anti-tumor immunotherapy combined with ICB therapy.

Treatment of Rheumatoid Arthritis Based on the Inherent Bioactivity of Black Phosphorus Nanosheets

Rheumatoid arthritis (RA) is an autoimmune disease that affects the living quality of patients, especially the elderly population. RA-related morbidity and mortality increase significantly with age, while current clinical drugs for RA are far from satisfactory and may have serious side effects. Therefore, the development of new drugs with higher biosafety and efficacy is demanding. Black phosphorus nanosheets (BPNSs) have been widely studied because of their excellent biocompatibility. Here, we focus on the inherent bioactivity of BPNSs, report the potential of BPNSs as a therapeutic drug for RA and elucidate the underlying therapeutic mechanism. We find that BPNSs inhibit autophagy at an early stage via the AMPK-mTOR pathway, switch the energy metabolic pathway to oxidative phosphorylation, increase intracellular ATP levels, suppress apoptosis, reduce inflammation and oxidative stress, and down-regulate senescence-associated secretory phenotype (SASP)-related genes in rheumatoid arthritis synovial fibroblasts (RA-SFs). Further, BPNSs induce the apoptosis of macrophages and promote their transition from the M1 to the M2 phenotype by regulating related cytokines. Significantly, the administration of BPNSs can alleviate key pathological features of RA in mice, revealing great therapeutic potential. This study provides a novel option for treating RA, with BPNSs emerging as a promising therapeutic candidate.

Fasting-Mimicking Diet Facilitates Anti-tumor Therapeutic Effects by Nutrient-Sensitive Nanocomposites

Cancer cells support their uncontrolled proliferation primarily by regulating energy metabolism. Inhibiting tumor growth by blocking the supply of nutrients is an effective treatment strategy. Fasting-mimicking diet (FMD), as a low-calorie, low-protein, low-sugar, high-fat diet, can effectively reduce the nutrient supply to tumor cells. However, the significant biological barrier presented by the tumor microenvironment imposes greater demands and challenges for drug design. This study constructs the multifunctional nanocomposite ZnFe2O4@TiO2@CHC@Orl-FA (ZTCOF), which has great potential to overcome the aforementioned drawbacks. ZnFe2O4@TiO2 could produce 1O2 with ultrasound, and stimulate the Fenton-like conversion of endogenous H2O2 to ·OH, achieving a combined therapeutic effect of sonodynamic therapy (SDT) and chemodynamic therapy (CDT). Orl (Orlistat) and CHC (α-cyano-4-hydroxycinnamic acid) not only block tumor cell energy metabolism but also increase sensitivity to reactive oxygen species, enhancing the cytotoxic effect on tumor cells. Furthermore, combining the treatment strategies with FMD condition control can further inhibit cancer cell energy metabolism, achieving significant synergistic anti-tumor therapy. Both in vitro and in vivo experiments confirm that ZTCOF with SDT/CDT/starvation can achieve effective tumor suppression and destruction. This work provides theoretical and technical support for anti-tumor multimodal synergistic therapy.

ATP Inhibition for Starvation/Mild Photothermal/Photodynamic Synergy Therapy Using Polypeptide Nanoparticles Conjugating 2-Deoxy-D-Glucose and Dye under NIR Phototheranostic Strategy

Rapid propagation of tumor cells requires plenty of energy, which is adenosine triphosphate (ATP) dependent. ATP inhibition in tumors not only results in the starvation of tumor cells but also down-regulation of the level of heat shock proteins (HSPs), which usually increase during traditional photothermal therapy (PTT), especially when the temperature is up 50 °C. 2-deoxy-D-glucose (2DG) is an anti-glycolytic reagent and can be used as an efficient agent for ATP inhibition in tumors. Compared with typical PTT, low-temperature mild photothermal therapy (MPTT) is receiving more and more attention because it avoids the high temperatures causing damage to the normal tissue, and the increase of HSPs which decrease PTT. Here, multifunctional polypeptide nanoparticles pDG@Ahx conjugating both a NIR probe Ahx-BDP and 2DG into the side chain of the amphiphilic polypeptide have been prepared. In vitro and in vivo studies reveal that the as-prepared nanoparticles achieve a synergistic effect of starvation/MPTT/PDT (photodynamic therapy), and it provides a new strategy to NIR-I/II fluorescence imaging-guided starvation/MPTT/PDT synergy therapy for tumors.

In situ autophagy regulation in synergy with phototherapy for breast cancer treatment

Autophagy is an important factor in reducing the efficacy of tumor phototherapy (including PTT and PDT). Accurate regulation of autophagy in tumor cells is a new strategy to improve the anti-tumor efficiency of PTT/PDT. This project intended to construct a tumor-activated autophagy regulator to efficiently block PTT/PDT-induced autophagy and realize synergistic sensitization to tumor phototherapy. To achieve this goal, we first synthesized TRANSFERRIN (Tf) biomimetic mineralized nano-tellurium (Tf-Te) as photosensitizer and then used disulfide bond reconstruction technology to induce Tf-Te self-assembly. The autophagy inhibitor hydroxychloroquine (HCQ) and iron ions carried by Tf were simultaneously loaded to prepare a tumor-responsive drug reservoir Tf-Te/HCQ. After entering breast cancer cells through the "self-guidance system", Tf-Te/HCQ can generate hyperpyrexia and ROS under NIR laser irradiation, to efficiently induce PTT/PDT effect. Meanwhile, the disulfide bond broke down in response to GSH, and the nanoparticles disintegrated to release Fe2+ and HCQ at fixed points. They simultaneously induce lysosomal alkalinization and increased osmotic pressure, effectively inhibit autophagy, and synergistically enhance the therapeutic effect of phototherapy. In vivo anti-tumor results have proved that the tumor inhibition rate of Tf-Te/HCQ can be as high as 88.6% on 4T1 tumor-bearing mice. This multifunctional drug delivery system might provide a new alternative for more precise and effective tumor phototherapy.

XQZ3, a Chlorella pyrenoidosa polysaccharide suppresses cancer progression by restraining mitochondrial bioenergetics via HSP90/AKT signaling pathway

The mitochondria are known to exert significant influence on various aspects of cancer cell physiology. The suppression of mitochondrial function represents a novel avenue for the advancement of anti-cancer pharmaceuticals. The heat shock protein HSP90 functions as a versatile regulator of mitochondrial metabolism in cancer cells, rendering as a promising target for anticancer interventions. In this work, a novel acid polysaccharide named as XQZ3 was extracted from Chlorella pyrenoidosa and purified by DEAE-cellulose and gel-filtration chromatography. The structural characteristic of XQZ3 was evaluated by monosaccharides composition, methylation analysis, TEM, FT-IR, and 2D-NMR. It was found that XQZ3 with a molecular weight of 29.13 kDa was a complex branched polysaccharide with a backbone mainly composed of galactose and mannose. It exhibited good antitumor activity in vitro and in vivo by patient-derived 3D organoid models and patient-derived xenografts models. The mechanistic investigations revealed that XQZ3 specifically interacted with HSP90, impeding the activation of the HSP90/AKT/mTOR signaling cascade. This, in turn, led to the induction of mitochondrial dysfunction, autophagy, and apoptosis, ultimately resulting in the demise of cancer cells due to nutrient deprivation. This study offers a comprehensive theoretical foundation for the advancement of XQZ3, a novel polysaccharide inhibitor targeting HSP90, with potential as an effective therapeutic agent against cancer.

Dressing and undressing MOF nanophotosensitizers to manipulate phototoxicity for precise therapy of tumors

Photodynamic therapy (PDT) is a clinically approved treatment for tumors, and it relies on the phototoxicity of photosensitizers by producing reactive oxygen species (ROS) to destroy cancer cells under light irradiation. However, such phototoxicity is a double-edged sword, which is also harmful to normal tissues. To manipulate phototoxicity and improve the therapy effect, herein we have proposed a dressing-undressing strategy for de-activating and re-activating therapy functions of photosensitizer nanoparticles. One kind of metal organic framework (PCN-224), which is composed of Zr(IV) cation and tetrakis (4-carboxyphenyl) porphyrin (TCPP), has been prepared as a model of photosensitizer, and it has size of ∼70 nm. These PCN-224 nanoparticles are subsequently coated with a mesoporous organic silica (MOS) shell containing tetrasulfide bonds (-S-S-S-S-), realizing the dressing of PCN-224. MOS shell has the thickness of ∼20 nm and thus can block 1O2 (diffusion distance: <10 nm), deactivating the phototoxicity and preventing the damage to skin and eyes. Furthermore, PCN-224@MOS can be used to load chemotherapy drug (DOX·HCl). When PCN-224@MOS-DOX are mixed with glutathione (GSH), MOS shell with -S-S-S-S- bonds can be reduced by GSH and then be decomposed, which results in the undressing and then confers the exposure of PCN-224 with good PDT function as well as the release of DOX. When PCN-224@MOS-DOX dispersion is injected into the mice and accumulated in the tumor, endogenous GSH also confers the undressing of PCN-224@MOS-DOX, realizing the in-situ activation of PDT and chemotherapy for tumor. Therefore, the present study not only demonstrates a general dressing-undressing strategy for manipulating phototoxicity of photosensitizers, but also provide some insights for precise therapy of tumors without side-effects. STATEMENT OF SIGNIFICANCE: Photosensitizers can generate reactive oxygen species (ROS) under light radiation to destroy cancer cells. However, this phototoxicity is a double-edged sword and also harmful to normal tissues such as the skin and eyes. To control phototoxicity and improve therapeutic efficacy, we prepared a PCN-224@MOS-DOX nanoplatform and proposed a dressing and undressing strategy to deactivate and reactivate the therapeutic function of the photosensitizer nanoparticles. The MOS shell can block the diffusion of 1O2, eliminate phototoxicity, and prevent damage to the skin and eyes. When injected into mice and accumulated in tumors, PCN-224@MOS-DOX dispersions are endowed with an endogenous GSH-driven undressing effect, achieving in situ activation of PDT and tumor chemotherapy.

Advancing Cancer Treatment: Enhanced Combination Therapy through Functionalized Porous Nanoparticles

Cancer remains a major global health challenge, necessitating the development of innovative treatment strategies. This review focuses on the functionalization of porous nanoparticles for combination therapy, a promising approach to enhance cancer treatment efficacy while mitigating the limitations associated with conventional methods. Combination therapy, integrating multiple treatment modalities such as chemotherapy, phototherapy, immunotherapy, and others, has emerged as an effective strategy to address the shortcomings of individual treatments. The unique properties of mesoporous silica nanoparticles (MSN) and other porous materials, like nanoparticles coated with mesoporous silica (NP@MS), metal-organic frameworks (MOF), mesoporous platinum nanoparticles (mesoPt), and carbon dots (CDs), are being explored for drug solubility, bioavailability, targeted delivery, and controlled drug release. Recent advancements in the functionalization of mesoporous nanoparticles with ligands, biomaterials, and polymers are reviewed here, highlighting their role in enhancing the efficacy of combination therapy. Various research has demonstrated the effectiveness of these nanoparticles in co-delivering drugs and photosensitizers, achieving targeted delivery, and responding to multiple stimuli for controlled drug release. This review introduces the synthesis and functionalization methods of these porous nanoparticles, along with their applications in combination therapy.

Nanoplatform-Mediated Autophagy Regulation and Combined Anti-Tumor Therapy for Resistant Tumors

The overall cancer incidence and death toll have been increasing worldwide. However, the conventional therapies have some obvious limitations, such as non-specific targeting, systemic toxic effects, especially the multidrug resistance (MDR) of tumors, in which, autophagy plays a vital role. Therefore, there is an urgent need for new treatments to reduce adverse reactions, improve the treatment efficacy and expand their therapeutic indications more effectively and accurately. Combination therapy based on autophagy regulators is a very feasible and important method to overcome tumor resistance and sensitize anti-tumor drugs. However, the less improved efficacy, more systemic toxicity and other problems limit its clinical application. Nanotechnology provides a good way to overcome this limitation. Co-delivery of autophagy regulators combined with anti-tumor drugs through nanoplatforms provides a good therapeutic strategy for the treatment of tumors, especially drug-resistant tumors. Notably, the nanomaterials with autophagy regulatory properties have broad therapeutic prospects as carrier platforms, especially in adjuvant therapy. However, further research is still necessary to overcome the difficulties such as the safety, biocompatibility, and side effects of nanomedicine. In addition, clinical research is also indispensable to confirm its application in tumor treatment.

Current Advances on Nanomaterials Interfering with Lactate Metabolism for Tumor Therapy

Increasing numbers of studies have shown that tumor cells prefer fermentative glycolysis over oxidative phosphorylation to provide a vast amount of energy for fast proliferation even under oxygen-sufficient conditions. This metabolic alteration not only favors tumor cell progression and metastasis but also increases lactate accumulation in solid tumors. In addition to serving as a byproduct of glycolytic tumor cells, lactate also plays a central role in the construction of acidic and immunosuppressive tumor microenvironment, resulting in therapeutic tolerance. Recently, targeted drug delivery and inherent therapeutic properties of nanomaterials have attracted great attention, and research on modulating lactate metabolism based on nanomaterials to enhance antitumor therapy has exploded. In this review, the advanced tumor therapy strategies based on nanomaterials that interfere with lactate metabolism are discussed, including inhibiting lactate anabolism, promoting lactate catabolism, and disrupting the "lactate shuttle". Furthermore, recent advances in combining lactate metabolism modulation with other therapies, including chemotherapy, immunotherapy, photothermal therapy, and reactive oxygen species-related therapies, etc., which have achieved cooperatively enhanced therapeutic outcomes, are summarized. Finally, foreseeable challenges and prospective developments are also reviewed for the future development of this field.

Phenylboronic Acid-Modified Near-Infrared Region II Excitation Donor-Acceptor-Donor Molecule for 2-Deoxy-d-Glucose Improved Starvation/Chemo/Photothermal Combination Therapy

Synergistic chemotherapy and photothermal therapy (PTT) have emerged as a promising anticancer paradigm to achieve expected therapeutic effects while mitigating side effects. However, the chemo/PTT combination therapy suffers from limited penetration depth, thermoresistance performance of tumor cells, and low drug bioavailability. Herein, multifunctional nanoparticles (BTP/DOX/2DG NPs) coloaded with near-infrared region II (NIR-II) light excitation donor-acceptor-donor (D-A-D) small molecules, doxorubicin (DOX), and 2-deoxy-d-glucose (2-DG) are developed for reinforced starvation/chemo/NIR-II PTT combination therapy. The synthesized phenylboronic acid (PBA)-modified water-soluble D-A-D molecule (BBT-TF-PBA) not only exhibits high binding ability to DOX and 2-DG through donor-acceptor coordination interactions PBA-diol bonds but also serves as a photoactive agent for NIR-II fluorescence imaging, NIR-II photoacoustic imaging, and NIR-II PTT. Under the acidic and oxidizing conditions in the tumor microenvironment, donor-acceptor coordination interactions and PBA-diol bond are decomposed, simultaneously releasing DOX and 2-DG from BTP/DOX/2DG NPs to achieve effective chemotherapy and starvation therapy. 2-DG also effectively inhibits the expression of heat shock protein and further enhances NIR-II PTT and chemotherapy efficiency. In vitro and in vivo experiments demonstrate the combination effect of BTP/DOX/2DG NPs for chemotherapy, NIR-II PTT, and starvation therapy.

A Nano-Autophagy Inhibitor Triggering Reciprocal Feedback Control of Cholesterol Depletion for Solid Tumor Therapy

Solid tumors are characterized by enhanced metabolism of lipid, particularly cholesterol, inspiring the exploration of metabolic therapy through cholesterol oxidase (COD)-mediated cholesterol deprivation. However, the therapeutic efficacy of COD is limited due to the hypoxic tumor microenvironment and the protective autophagy triggered by cholesterol deprivation. Herein, a combination therapy for metabolically treating solid tumors through COD in conjunction with molybdenum oxide nanodots (MONDs), which serve as both potent oxygen generators and autophagy inhibitors, is reported. MONDs convert H2 O2 (arising from COD-mediated cholesterol oxidation) into O2 , which is then recycled by COD to form reciprocal feedback for cholesterol depletion. Concurrently, MONDs can overcome autophagy-induced therapeutic resistance frequently occurring in conventional nutrient deprivation therapy by activating AKT/mTOR pathway phosphorylation. Combination therapy in the xenograft model results in an ≈5-fold increase in therapeutic efficiency as compared with COD treatment alone. This functionally cooperative metabolic coupling strategy holds great promise as a novel polytherapy approach that will benefit patients with solid tumors.

Acidity-Responsive Nanoreactors Destructed "Warburg Effect" for Toxic-Acidosis and Starvation Synergistic Therapy

"Warburg Effect" shows that most tumor cells rely on aerobic glycolysis for energy supply, leading to malignant energy deprivation and an "internal alkaline external acid" tumor microenvironment. Destructing the "Warburg Effect" is an effective approach to inhibit tumor progression. Herein, an acidity-responsive nanoreactor (Au@CaP-Flu@HA) is fabricated for toxic acidosis and starvation synergistic therapy. In the nanoreactor, the fluvastatin (Flu) could reduce lactate efflux by inhibiting the lactate-proton transporter (monocarboxylate transporters, MCT4), resulting in intracellular lactate accumulation. Meanwhile, the glucose oxidase-mimic Au-nanocomposite consumes glucose to induce cell starvation accompanied by gluconic acid production, coupling with lactate to exacerbate toxic acidosis. Also, the up-regulated autophagic energy supply of tumor cells under energy deprivation and hypoxia aggravation is blocked by autophagy inhibitor CaP. Cellular dysfunction under pHi acidification and impaired Adenosine Triphosphate (ATP) synthesis under starvation synergistically promote tumor cell apoptosis. Both in vitro and in vivo studies demonstrate that this combinational approach of toxic-acidosis/starvation therapy could effectively destruct the "Warburg Effect" to inhibit tumor growth and anti-metastatic effects.

Recent Advances in the Biological Responses to Nano-black Phosphorus: Understanding the Importance of Intrinsic Properties and Cell Types

The production scalability and increasing demand for nano-black phosphorus materials (nano-BPs) inevitably lead to their environmental leakage, thereby raising the risk of human exposure through inhalation, ingestion, dermal, and even intravenous pathways. Consequently, a systematic evaluation of their potential impacts on human health is necessary. This Review outlines recent progress in the understanding of various biological responses to nano-BPs. Attention is particularly given to the inconsistent toxicological findings caused by a wide variation of nano-BPs' physicochemical properties, toxicological testing methods, and cell types examined in each study. Additionally, cellular uptake and intracellular trafficking, cell death modes, immunological effects, and other biologically relevant processes are discussed in detail, providing evidence for the potential health implications of nano-BPs. Finally, we address the remaining challenges related to the health risk evaluation of nano-BPs and propose a broader range of applications for these promising nanomaterials.

Bioorthogonal Disruption of Pyroptosis Checkpoint for High-Efficiency Pyroptosis Cancer Therapy

Pyroptosis is an inflammatory form of programmed cell death that holds great promise in cancer therapy. However, autophagy as the crucial pyroptosis checkpoint and the self-protective mechanism of cancer cells significantly weakens the therapeutic efficiency. Here, a bioorthogonal pyroptosis nanoregulator is constructed to induce pyroptosis and disrupt the checkpoint, enabling high-efficiency pyroptosis cancer therapy. The nanoregulator allows the in situ synthesis and accumulation of the photosensitizer PpIX in the mitochondria of cancer cells to directly produce mitochondrial ROS, thus triggering pyroptosis. Meanwhile, the in situ generated autophagy inhibitor via palladium-catalyzed bioorthogonal chemistry can disrupt the pyroptosis checkpoint to boost the pyroptosis efficacy. With the biomimetic cancer cell membrane coating, this platform for modulating pyroptosis presents specificity to cancer cells and poses no harm to normal tissue, resulting in a highly efficient and safe antitumor treatment. To our knowledge, this is the first report on a disrupting intrinsic protective mechanism of cancer cells for tumor pyroptosis therapy. This work highlights that autophagy as a checkpoint plays a key regulative role in pyroptosis therapy, which would motivate the future design of therapeutic regimens.

Mitochondria-Anchoring Self-assembled Nanoparticles for Multi-Path Energy Depletion: A "Nano Bomb" in Chemo-co-Starvation Therapy

As the main systemic treatment for triple-negative breast cancer (TNBC), the bleak medical prognosis of chemotherapy resulted in impaired life quality by tumor recurrence and metastasis. The feasible cancer starvation therapy could inhibit tumor progression by blocking energy supplements, however, the mono-therapeutic modality showed limited curing efficacy due to heterogeneity and abnormal energy metabolism of TNBC. Thus, the development of a synergistic nano-therapeutic modality involving different anti-tumor mechanisms to simultaneously transport medicines to the organelle where metabolism took place, might remarkably improve curing efficacy, targeting ability, and bio-safety. Herein, the hybrid BLG@TPGS NPs were prepared by doping multi-path energy inhibitors Berberine (BBR) and Lonidamine (LND) as well as the chemotherapeutic agent Gambogic acid (GA). Our research indicated that Nanobomb\mathord{-} BLG@TPGS NPs inherited the mitochondria targeting ability from BBR to accumulate precisely at the "energy factory" mitochondria, and then induce starvation therapy to efficiently eradicated cancer cells by coordinately powered off tumor cells via a "three-prone strategy" to cut off mitochondrial respiration, glycolysis, and glutamine metabolism. The inhibition of tumor proliferation and migration was enlarged by the synergistic combination with chemotherapy. Besides, apoptosis via mitochondria pathway and mitochondria fragmentation supported the hypothesis that NPs eliminated MDA-MB-231 cells by violently attacking MDA-MB-231 cells and especially the mitochondria. In summary, this synergistic chemo-co-starvation nanomedicine proposed an innovative site-specific targeting strategy for improved tumor treatment and decreased toxicity to normal tissues, which provided an option for clinical TNBC-sensitive treatment.

Stimuli-responsive cancer nanomedicines inhibit glycolysis and impair redox homeostasis

The solid tumors are characterized with oxidative stress and metabolic reprogramming, which has been independently used for targeted tumor monotherapy. However, the potential of targeting metabolism-redox circuit in tumor therapy has long been neglected. Herein, we report a hybrid nanocarrier for concurrent targeting of glycolysis and redox balance in the current work. The nanocarriers are made of pH- and ATP-responsive zeolitic imidazolate framework (ZIF-8) as the porous core that was further coated with poloxamer 407 as the steric stabilizer. Two active cargos, glucose oxidase (GOx) and 3-bromopyruvate (3-BrPA) were co-loaded in the core of nanocarrier. GOx is well-known for its ability of producing hydrogen peroxide at the expense of glucose and oxygen. 3-BrPA can reduce oxygen and glucose consumption through glycolysis, which sensitized cancer cells to GOx-induced apoptosis. At the cellular level, the hybrid nanocarrier significantly impaired the redox balance in the liver hepatocellular carcinoma cell line (HepG2), as evidenced by the depletion of glutathione and boost of reactive oxygen species. The potency of hybrid nanocarrier in terms of suppressing HepG2 cell energy metabolism was proven by the exhaustion of ATP. As a consequence, cell viability was greatly reduced. The in vivo efficacy of hybrid nanocarriers was demonstrated in HepG2 tumor-bearing mice. The current work presents an approach of targeting metabolism-redox circuit for tumor treatment, which may enrich the available anti-tumor strategies. STATEMENT OF SIGNIFICANCE: Metabolic alterations and elevated reactive oxygen species (ROS) are two characteristics of cancer. The metabolic patterns of cancer cells are elaborately reprogrammed to enable the rapid propagation of cancer cells. However, the potential of targeting the metabolism-redox circuit in anti-tumor therapy has long been neglected. As a proof-of-concept, we report an engineered stimuli-responsive nanomedicine that can eradicate cancer cells via cooperative glycolysis inhibition and redox impairment. The current work presents an approach of targeting the metabolism-redox circuit for tumor treatment, which may enrich the available anti-tumor strategies.

Autophagy-Activated Self-reporting Photosensitizer Promoting Cell Mortality in Cancer Starvation Therapy

Cancer starvation therapy have received continuous attention as an efficient method to fight against wide-spectrum cancer. However, during cancer starvation therapy, the protective autophagy promotes cancer cells survival, compromising the therapeutic effect. Herein, a novel strategy by combination of autophagy-activated fluorescent photosensitizers (PSs) and cancer starvation therapy to realize the controllable and efficient ablation of tumor is conceived. Two dual-emissive self-reporting aggregation-induced emission luminogens (AIEgens), TPAQ and TPAP, with autophagy-activated reactive oxygen species (ROS) generation are prepared to fight against the protective autophagy in cancer starvation therapy. When protective autophagy occurs, a portion of TPAQ and TPAP will translocate from lipid droplets to acidic lysosomes with significant redshift in fluorescence emission and enhanced ROS generation ability. The accumulation of ROS induced by TPAQ-H and TPAP-H causes lysosomal membrane permeabilization (LMP), which further results in cell apoptosis and promotes cell death. In addition, TPAQ and TPAP can enable the real-time self-reporting to cell autophagy and cell death process by observing the change of red-emissive fluorescence signals. Particularly, the efficient ablation of tumor via the combination of cancer starvation therapy and photodynamic therapy (PDT) induced by TPAQ has been successfully confirmed in 3D tumor spheroid chip, suggesting the validation of this strategy.

Mitochondria-Targeting Pyroptosis Amplifier of Lonidamine-Modified Black Phosphorus Nanosheets for Glioblastoma Treatments

Pyroptosis is accompanied by immunogenic mediators' release and serves as an innovative strategy to reprogram tumor microenvironments. However, damaged mitochondria, the origin of pyroptosis, are frequently eliminated by mitophagy, which will severely impair pyroptosis-elicited immune activation. Herein, black phosphorus nanosheets (BP) are employed as a pyroptosis inducer delivery and mitophagy flux blocking system since the degradation of BP could impair lysosomal function by altering the pH within lysosomes. The pyroptosis inducer of lonidamine (LND) was precoupled with the mitochondrial target moiety of triphenylphosphonium to facilitate the occurrence of pyroptosis. The mitochondria-targeting LND-modified BP (BP_TLD) were further encapsulated into the macrophage membrane to endow the BP_TLD with blood-brain barrier penetration and tumor-targeting capability. The antitumor activities of membrane-encapsulated BP_TLD (M@BP_TLD) were investigated using a murine orthotopic glioblastoma model. The results demonstrated that the engineered nanosystem of M@BP_TLD could target the mitochondria, and induce as well as reinforce pyroptosis via mitophagy flux blocking, thereby boosting the release of immune-activated factors to promote the maturation of dendritic cells. Furthermore, upon near-infrared (NIR) irradiation, M@BP_TLD induced stronger mitochondrial oxidative stress, which further advanced robust immunogenic pyroptosis in glioblastoma cells. Thus, this study utilized the autophagy flux inhibition and phototherapy performance of BP to amplify LND-mediated pyroptosis, which might greatly contribute to the development of pyroptosis nanomodulators.

Recent Development of Rhenium-Based Materials in the Application of Diagnosis and Tumor Therapy

Rhenium (Re) is widely used in the diagnosis and treatment of cancer due to its unique physical and chemical properties. Re has more valence electrons in its outer shell, allowing it to exist in a variety of oxidation states and to form different geometric configurations with many different ligands. The luminescence properties, lipophilicity, and cytotoxicity of complexes can be adjusted by changing the ligand of Re. This article mainly reviews the development of radionuclide 188Re in radiotherapy and some innovative applications of Re as well as the different therapeutic approaches and imaging techniques used in cancer therapy. In addition, the current application and future challenges and opportunities of Re are also discussed.

Short-Term Starvation Weakens the Efficacy of Cell Cycle Specific Chemotherapy Drugs through G1 Arrest

Short-term starvation (STS) during chemotherapy can block the nutrient supply to tumors and make tumor cells much more sensitive to chemotherapeutic drugs than normal cells. However, because of the diversity of starvation methods and the heterogeneity of tumors, this method's specific effects and mechanisms for chemotherapy are still poorly understood. In this study, we used HeLa cells as a model for short-term starvation and etoposide (ETO) combined treatment, and we also mimicked the short-term starvation effect by knocking down the glycolytic enzyme GAPDH to explore the exact molecular mechanism. In addition, our study demonstrated that short-term starvation protects cancer cells against the chemotherapeutic agent ETO by reducing DNA damage and apoptosis due to the STS-induced cell cycle G1 phase block and S phase reduction, thereby diminishing the effect of ETO. Furthermore, these results suggest that starvation therapy in combination with cell cycle-specific chemotherapeutic agents must be carefully considered.

Nanozyme-laden intelligent macrophage EXPRESS amplifying cancer photothermal-starvation therapy by responsive stimulation

Precise delivery and responsive activation of therapeutic agents are critical for tumor precise therapy. Herein, inspired by intelligent express, a nanozyme-laden intelligent macrophage express was fabricated based on IR 820-macrophage loaded with GOx nanozymes for tumor-targeted photothermal-amplified starvation therapy with fluorescence imaging guidance. The nanozyme-laden intelligent macrophage express exerted precise delivery through cargo loading, conveying and unloading. For efficient cargo loading, H₂O₂-sensitive GOx nanozymes with blocked enzymatic activity were packaged on macrophage expresses with excellent phagocytic ability. Due to the inherent tumor tropism, the therapeutic agents-laden macrophage expresses naturally accumulated at tumor site with fluorescence navigation to track the conveying process. The spatiotemporal unpacking of the laden therapeutic agents at tumor site was triggered by the external laser for the macrophage express photothermal property. The released special tumor-microenvironment responsive GOx nanozymes were activated by H₂O₂ in tumor to start starvation therapy. Photothermal therapy generated mild hyperthermia and starvation therapy produced H₂O₂ further increased the nanozymes enzymatic activity, enhancing GOx-mediated starvation therapy. The nanozyme-laden intelligent macrophage express integrated laser-induce drug release and activation, tumor microenvironment-responsiveness, and circular amplification property, achieving the synergistic effects of PTT and starvation therapy in vitro and in vivo.

New Visions on Natural Products and Cancer Therapy: Autophagy and Related Regulatory Pathways

Macroautophagy (autophagy) has been a highly conserved process throughout evolution and allows cells to degrade aggregated/misfolded proteins, dysfunctional or superfluous organelles and damaged macromolecules, in order to recycle them for biosynthetic and/or energetic purposes to preserve cellular homeostasis and health. Changes in autophagy are indeed correlated with several pathological disorders such as neurodegenerative and cardiovascular diseases, infections, cancer and inflammatory diseases. Conversely, autophagy controls both apoptosis and the unfolded protein response (UPR) in the cells. Therefore, any changes in the autophagy pathway will affect both the UPR and apoptosis. Recent evidence has shown that several natural products can modulate (induce or inhibit) the autophagy pathway. Natural products may target different regulatory components of the autophagy pathway, including specific kinases or phosphatases. In this review, we evaluated ~100 natural compounds and plant species and their impact on different types of cancers via the autophagy pathway. We also discuss the impact of these compounds on the UPR and apoptosis via the autophagy pathway. A multitude of preclinical findings have shown the function of botanicals in regulating cell autophagy and its potential impact on cancer therapy; however, the number of related clinical trials to date remains low. In this regard, further pre-clinical and clinical studies are warranted to better clarify the utility of natural compounds and their modulatory effects on autophagy, as fine-tuning of autophagy could be translated into therapeutic applications for several cancers.

Enhanced Sensitivity of Tumor Cells to Autophagy Inhibitors Using Fasting-Mimicking Diet and Targeted Lysosomal Delivery Nanoplatform

Autophagy is one of the key pathways for tumor cell survival and proliferation. Therefore, inhibition of autophagy has been extensively studied for cancer therapy. However, current autophagy inhibitors lack specificity and are ineffective in limiting tumor progression. Herein, we report a nanoplatform for tumor-site-targeted delivery of hydroxychloroquine (HCQ) using insulin-like growth factors 2 receptor (IGF2R)-targeted liposomes (iLipo-H). A fasting-mimicking diet (FMD) is used to increase the autophagy levels in tumor cells, thereby increasing the sensitivity of tumor cells to HCQ. In addition, FMD treatment upregulates the expression of IGF2R in tumor cells, but not normal cells. Consequently, iLipo-H nanoparticles efficiently accumulate at the tumor site under FMD condition. In vivo studies demonstrate that iLipo-H nanoparticles efficiently inhibit 4T1 tumor growth without obvious side effects, especially under FMD condition. This study provides a promising strategy to increase the sensitivity of tumor cells to autophagy inhibitors for effective cancer therapy.

Biodegradable Ferrous Sulfide-Based Nanocomposites for Tumor Theranostics through Specific Intratumoral Acidosis-Induced Metabolic Symbiosis Disruption

Abnormal metabolic symbiosis is a typical characteristic that differentiates the tumor regions from healthy tissues and meanwhile maintains tumor survival. It is of great potential to disrupt intratumoral metabolic symbiosis in tumor therapy. Herein, we report a specific tumor therapy strategy through inducing acidosis to disrupt intratumoral metabolic symbiosis for tumor elimination, which is based on carbonic anhydrase inhibitor (CAI)-modified ferrous sulfide nanoparticles (FeS-PEG-CAI NPs). The FeS-PEG-CAI NPs show the acid-responsive degradation capacity to release functional components, including CAI, Fe²⁺, and H₂S, while remaining quite stable under normal physiological conditions. The generated CAI and H₂S gas can not only disrupt the intracellular metabolic symbiosis to induce acidosis but also provide suitable circumstances for Fe²⁺-mediated Fenton reaction, producing abundant toxic hydroxyl radicals. Meanwhile, these NPs also show the dual-mode imaging capacity with photoacoustic and magnetic resonance imaging, which can dynamically monitor tumor location in the process of synergistic chemodynamic/photothermal/gas therapy. Overall, the developed FeS-PEG-CAI NPs exert their role of disrupting intratumoral metabolic symbiosis and other synergistic effects, which further enrich tumor treatment strategies.

Electron attachment to fluorodeoxyglucose: Dissociation dynamics in a molecule of near-zero electron affinity

Fluorodeoxyglucose (FDG) is a glucose derivative with fluorine at the C₂ position. The molecule containing the radioactive F-18 isotope is well known from its application in positron emission tomography as a radiotracer in tumor examination. In the stable form with the F-19 isotope, FDG was proposed as a potential radiosensitizer. Since reduction processes may be relevant in radiosensitization, we investigated low-energy electron attachment to FDG with a crossed electron-molecule beam experiment and with quantum chemical calculations as well as molecular dynamics at elevated temperatures to reveal statistical dissociation. We experimentally find that the susceptibility of FDG to low-energy electrons is relatively low. The calculations indicate that upon attachment of an electron with a kinetic energy of ∼0 eV, only dipole-bound states are accessible, which agrees with the weak ion yields observed in the experiment. The temporary negative ions formed upon electron attachment to FDG may decay by a large variety of dissociation reactions. The major fragmentation channels include H₂O, HF, and H₂ dissociation, accompanied by ring opening.

Oncolytic Impediment/Promotion Balance Disruption by Sonosensitizer-Free Nanoplatforms Unfreezes Autophagy-Induced Resistance to Sonocatalytic Therapy

Autophagy as a double-edged sword features an oncolytic impediment/promotion balance, which manipulates tumor progression. From this perspective, a sonosensitizer-free targeting oncolytic nanoplatform (SFTON) consisting of chloroquine (CQ) and porphyrin-structured metal centers (PMCS) was engineered to break this balance for enhancing antitumor activity. Porphyrin structure retention in a ZIF-8-derived hydrophobic carbon skeleton retained high stability and high sonocatalytic activity, and the hydrophobic carbon skeleton capable of adsorbing air provided cavitation nuclei for further elevating sonocatalytic activity. More significantly, the encapsulated CQ as the autophagy inhibitor reprogrammed autophagy, terminated the autophagy-induced self-protection or self-detoxification, and unfroze the resistances to reactive oxygen species (ROS) therapy associated with ROS accumulation and ROS activity. Systematic experiments reveal the action principles and validate that the induced apoptosis and blockaded autophagosome escalation into the autolysosome were two activated pathways to magnify the antitumor sonocatalytic therapy. Contributed by these actions, the SFTON-unlocked oncolytic impediment/promotion balance disruption strategy acquired considerable antitumor outcomes in vivo and in vitro against liver tumor progression, especially after combining with AS1411-mediated active targeting. This impediment/promotion balance disruption enabled by the SFTON can serve as a general method to elevate ROS-based antitumor activity.

Pump proton inhibitors display anti-tumour potential in glioma

OBJECTIVES

Glioma is one of the most aggressive brain tumours with poor overall survival despite advanced technology in surgical resection, chemotherapy and radiation. Progression and recurrence are the hinge causes of low survival. Our aim is to explain the concrete mechanism in the proliferation and progression of tumours based on tumour microenvironment (TME). The main purpose is to illustrate the mechanism of proton pump inhibitors (PPIs) in affecting acidity, hypoxia, oxidative stress, inflammatory response and autophagy based on the TME to induce apoptosis and enhance the sensitivity of chemoradiotherapy.

FINDINGS

TME is the main medium for tumour growth and progression. Acidity, hypoxia, inflammatory response, autophagy, angiogenesis and so on are the main causes of tumour progress. PPIs, as a common clinical drug to inhibit gastric acid secretion, have the advantages of fast onset, long action time and small adverse reactions. Nowadays, several kinds of literature highlight the potential of PPIs in inhibiting tumour progression. However, long-term use of PPIs alone also has obvious side effects. Therefore, till now, how to apply PPIs to promote the effect of radio-chemotherapy and find the concrete dose and concentration of combined use are novel challenges.

CONCLUSIONS

PPIs display the potential in enhancing the sensitivity of chemoradiotherapy to defend against glioma based on TME. In the clinic, it is also necessary to explore specific concentrations and dosages in synthetic applications.

A Nanounit Strategy Disrupts Energy Metabolism and Alleviates Immunosuppression for Cancer Therapy

Aberrant energy metabolism not only endows tumor cells with unlimited proliferative capacity but also contributes to the establishment of the glucose-deficient/lactate-rich immunosuppressive tumor microenvironment (ITM) impairing antitumor immunity. Herein, a novel metabolic nanoregulator (D/B/CQ@ZIF-8@CS) was developed by enveloping 2-deoxy-d-glucose (2-DG), BAY-876, and chloroquine (CQ) into zeolitic imidazolate framework-8 (ZIF-8) to simultaneously deprive the energy/nutrition supply of tumor cells and relieve the ITM for synergetic tumor starvation-immunotherapy. Aerobic glycolysis, glucose uptake, and autophagy flux could be concurrently blocked by D/B/CQ@ZIF-8@CS, cutting off the nutrition/energy supply and the source of lactate. Furthermore, inhibition of glucose uptake and aerobic glycolysis could effectively reverse the glucose-deficient/lactate-rich ITM, thus functionally inactivating regulatory T cells and augmenting anti-CTLA-4 immunotherapy. Such a two-pronged strategy would provide new insights for the design of metabolic intervention-based synergistic cancer therapy.

Glucose Metabolism Intervention-Facilitated Nanomedicine Therapy

Ordinarily, cancer cells possess features of abnormally increased nutrient intake and metabolic pathways. The disorder of glucose metabolism is the most important among them. Therefore, starvation therapy targeting glucose metabolism specifically, which results in metabolic disorders, restricted synthesis, and inhibition of tumor growth, has been developed for cancer therapy. However, issues such as inadequate targeting effectiveness and drug tolerance impede their clinical transformation. In recent years, nanomaterial-assisted starvation treatment has made significant progress in addressing these challenges, whether as a monotherapy or in combination with other medications. Herein, representative researches on the construction of nanosystems conducting starvation therapy are introduced. Elaborate designs and interactions between different treatment mechanisms are meticulously mentioned. Not only are traditional treatments based on glucose oxidase involved, but also newly sprung small molecule agents targeting glucose metabolism. The obstacles and potential for advancing these anticancer therapies were also highlighted in this review.

Cascade nanozymes based on the "butterfly effect" for enhanced starvation therapy through the regulation of autophagy

Although tumor starvation therapy has been proven to be an excellent method for tumor therapy, its efficiency may be weakened by autophagy, a self-protection mechanism exerted by tumors under starvation stress. Interestingly, over-activated autophagy not only improves the efficacy of starvation therapy, but also induces autophagic death. Herein, we report cascade nanozymes for enhanced starvation therapy by inducing over-activated autophagy. First, glucose oxidase (GOx) modified metal-organic frameworks (NH₂-MIL88, MOF) were constructed (MOF-GOx). After loading with curcumin (Cur), Cur@MOF-GOx was further decorated with tumor-targeting hyaluronic acid (HA) to obtain Cur@MOF-GOx/HA nanozymes. GOx can catalyze glucose into H₂O₂ and gluconic acid, which not only leads to tumor starvation, but also provides reactants for the Fenton reaction mediated by the MOF to generate hydroxyl radicals (˙OH) for chemo-dynamic therapy. Most importantly, protective autophagy caused by tumor starvation can be over-activated by Cur to convert autophagy from pro-survival to pro-death, realizing augmented anticancer therapy efficacy. With these cascade reactions, the synergistic action of starvation, autophagy and chemo-dynamic therapy was realized. Generally, the introduction of Cur@MOF-GOx/HA into tumor cells leads to a "butterfly effect", which induces enhanced starvation therapy through subsequent autophagic cell death to completely break the self-protective mechanism of cancer cells, and generate ˙OH for chemo-dynamic therapy. Precise design allows for the use of cascade nanozymes to realize efficient cancer treatment and restrain metastasis.

Tumor metabolism destruction via metformin-based glycolysis inhibition and glucose oxidase-mediated glucose deprivation for enhanced cancer therapy

Cancer cells rely on glycolysis to support a high proliferation rate. Metformin (Met) is a promising drug for tumor treatment that targets hexokinase 2 (HK2) to block the glycolytic process, thereby further disrupting the metabolism of cancer cells. Herein, an intelligent nanomedicine based on glucose deprivation and glycolysis inhibition is creatively constructed for enhanced cancer synergistic treatment. In brief, Met and glucose oxidase (GOx) was encapsulated into histidine/zeolitic imidazolate framework-8 (His/ZIF-8), which was followed by coating with Arg-Gly-Asp (RGD) peptides to obtain the desired nanomedicine (Met/GOx@His/ZIF-8∼RGD). This smart nanomedicine presents the controllable Met and GOx release behavior in an acidic responsive manner. The liberated Met blocks the glycolysis process via suppressing the activity of HK2 and impairing ATP production, which activates the AMP-activated protein kinase (AMPK) pathway and p53 pathway and damages the Warburg effect, eventually leading to cells apoptosis. And the GOx boosts the glucose shortage for starvation therapy by depleting accumulated glucose. According to in vitro and in vivo assays, the combination of glycolysis inhibition and starvation therapy demonstrates efficient cancer cells growth suppression and superior antitumor properties compared to the Met based or GOx-mediated monotherapy. This work provides an advanced therapeutic strategy via disrupting cellular metabolism against cancer. STATEMENT OF SIGNIFICANCE: The obtained nanomedicine (Met/GOx@His/ZIF-8∼RGD) presents the controllable Met and glucose oxidase (GOx) release behavior in an acidic responsive manner. The liberated Met blocks the glycolysis process via suppressing the activity of HK2 and impairing ATP production, which activates the AMP-activated protein kinase (AMPK) pathway and p53 pathway and damages the Warburg effect, eventually leading to cells apoptosis. And the GOx boosts the glucose shortage for starvation therapy by depleting accumulated glucose. The combination of glycolysis inhibition and starvation therapy demonstrate the efficient suppression of cancer cells growth and the superior antitumor properties when compared to the Met based or GOx-mediated monotherapy.

Enhanced Cancer Starvation Therapy Enabled by an Autophagy Inhibitors-Encapsulated Biomimetic ZIF-8 Nanodrug: Disrupting and Harnessing Dual Pro-Survival Autophagic Responses

Autophagy is an important protective mechanism in maintaining or restoring cell homeostasis under physiological and pathological conditions. Nanoparticles (NPs) with certain components and morphologies can induce autophagic responses in cancer cells, providing a new perspective for establishing cancer therapy strategies. Herein, a novel nanodrug system, cell membranes-coated zeolitic imidazolate framework-8 (ZIF-8) NPs encapsulating chloroquine (CQ) and glucose oxidase (GOx) (defined as mCG@ZIF), is designed to achieve an enhanced anticancer effect with the combination of starvation therapy and an autophagy regulation strategy. It is found that ZIF-8 as a nanocarrier can induce autophagy to promote survival of cancer cells via the upstream Zn²⁺-stimulated mitochondrial reactive oxygen species (ROS) so that the anticancer effect is directly achieved by inhibiting this pro-survival autophagy using CQ released from mCG@ZIF under a tumor acidic microenvironment. Moreover, a cancer cell under starvation caused by GOx harnesses autophagy to maintain intracellular ATP levels and resist starvation therapy. The released CQ further inhibits the starvation-induced pro-survival autophagy and cuts off the protective pathway of cancer cells, enhancing the anticancer efficiency of GOx-based starvation therapy. Significantly, the cell membrane coating endows mCG@ZIF with excellent in vivo homotypic targeting ability. Both in vitro and in vivo results have confirmed the enhanced anticancer effect achieved by mCG@ZIF with a negligible side effect.

Boosting nutrient starvation-dominated cancer therapy through curcumin-augmented mitochondrial Ca2+ overload and obatoclax-mediated autophagy inhibition as supported by a novel nano-modulator GO-Alg@CaP/CO

BACKGROUND

By hindering energy supply pathway for cancer cells, an alternative therapeutic strategy modality is put forward: tumor starvation therapy. And yet only in this blockade of glucose supply which is far from enough to result in sheer apoptosis of cancer cells.

RESULTS

In an effort to boost nutrient starvation-dominated cancer therapy, here a novel mitochondrial Ca²⁺ modulator Alg@CaP were tailor-made for the immobilization of Glucose oxidase for depriving the intra-tumoral glucose, followed by the loading of Curcumin to augment mitochondrial Ca²⁺ overload to maximize the therapeutic efficiency of cancer starvation therapy via mitochondrial dysfunctions. Also, autophagy inhibitors Obatoclax were synchronously incorporated in this nano-modulator to highlight autophagy inhibition.

CONCLUSION

Here, a promising complementary modality for the trebling additive efficacy of starvation therapy was described for cutting off the existing energy sources in starvation therapy through Curcumin-augmented mitochondrial Ca²⁺ overload and Obatoclax-mediated autophagy inhibition.

Oxygen-deficient titanium dioxide-loaded black phosphorus nanosheets for synergistic photothermal and sonodynamic cancer therapy

Malignant tumors, particularly those located in deep tissues, have always been a grievous threat to human health. Sonodynamic therapy (SDT) has recently attracted great attention due to deep tissue penetration. However, the lack of effective sonosensitizers and the poor therapeutic efficacy severely limit their wider use. Herein, dual-functionalized black phosphorus nanosheets (BP@PEI-PEG, i.e., PPBP) integrating black oxygen-deficient titanium dioxide particles (B-TiO₂) were successfully constructed (PPBP-B-TiO₂) for synergistic photothermal (PTT)/sonodynamic therapy. In these nanocomposites, black titanium dioxide can enhance the separation of electrons (e^-) and holes (h⁺) due to the oxygen-deficient structure and significantly improves the production of reactive oxygen species (ROS) for SDT, while the BP nanosheets endow the nanocomposites with a higher photothermal conversion capability for photothermal therapy (η = 44.1%) which can prolong the blood circulation and improve the O₂ supply. In vivo experiments prove that PPBP-B-TiO₂ nanocomposites exhibited outstanding tumor inhibition efficacy and excellent biocompatibility. This work provides a prospective platform for combined photothermal/sonodynamic cancer therapy.

Two-Dimensional Nanomaterial-based catalytic Medicine: Theories, advanced catalyst and system design

Two-dimensional nanomaterial-based catalytic medicines that associate the superiorities of novel catalytic mechanisms with nanotechnology have emerged as absorbing therapeutic strategies for cancer therapy. Catalytic medicines featuring high efficiency and selectivity have been widely used as effective anticancer strategies without applying traditional nonselective and highly toxic chemodrugs. Moreover, two-dimensional nanomaterials are characterized by distinctive physicochemical properties, such as a sizeable bandgap, good conductivity, fast electron transfer and photoelectrochemical activity. The introduction of two-dimensional nanomaterials into catalytic medicine provides a more effective, controllable, and precise antitumor strategy. In this review, different types of two-dimensional nanomaterial-based catalytic nanomedicines are generalized, and their catalytic theories, advanced catalytic pathways and catalytic nanosystem design are also discussed in detail. Notably, future challenges and obstacles in the design and further clinical transformation of two-dimensional nanomaterial-based catalytic nanomedicine are prospected.

Current status of cancer starvation therapy

Conventional therapies for malignant tumors have limitations and disadvantages. In recent years, the cancer starvation therapy has emerged which intends to deprive cancer cells of nutritional supply. There are several approaches to"starve" cancer cells: to intervene tumor angiogenesis by targeted inhibition of angiogenic factors or their receptors and integrins; to block the blood supply of cancer cells by embolizing or compressing blood vessels; to intervene metabolic process of cancer cells by inhibition of the signal pathways of mitochondrial serine-glycine-one earbon metabolism, glycolysis and amino acid metabolism; cancer starvation therapy can be employed with oxidation therapy, chemotherapy, sonodynamic therapy, anti-autophagy therapy or other therapies to achieve synergistic effects. This article reviews the research progress of cancer starvation therapy in recent years and discusses the existing problems.

Engineering the Surface of Ti3C2 MXene Nanosheets for High Stability and Multimodal Anticancer Therapy

The surface of Ti₃C₂ MXene nanosheets (TC NSs) was first modified with the antioxidants sodium ascorbate (SA) and dopamine (DA) (DSTC NS) to improve their stability in oxidative and hydration environments and thereby improve their bioapplications. This novel approach not only improved MXene stability by arresting oxidation but also increased the available functional groups for further functionalization with various biomolecules. The DSTC NSs were then sequentially conjugated with enzyme glucose oxidase (GOx) and photosensitizer Ce6 to render the obtained CGDSTC NSs with glucose starvation and photodynamic therapeutic properties and thus attain high efficiency in killing cancer cells through the cooperative effect. The as-synthesized CGDSTC NSs demonstrated tremendous photothermal effect with conversion efficiency of 45.1% and photodynamic (ROS generation) properties upon irradiation with 808 and 671 nm lasers. Furthermore, it was observed that the enzymatic activity of CGDSTC NSs increased upon laser irradiation due to enhanced solution temperature. During in vitro studies, the CGDSTC NSs exhibited cytocompatability to HePG2 and HeLa cells under nonstimulus conditions. However, they elicited more than 90% cell-killing efficiency in the presence of glucose and laser irradiation via the cooperative effect between starvation therapy and phototherapy. These results indicate that CGDSTC NSs could be used as potential therapeutic agents to eradicate cancers with no or few adverse effects. This surface modification approach is also simple and facile to adopt in MXene-based research.

Smart Tumor Microenvironment-Responsive Nano-Prodrug for Disulfiram Toxification In Situ and the Exploration of Lethal Mechanisms in Cells

Disulfiram (DSF) is a clinical antialcoholism drug that has been confirmed to show anticancer bioactivity after chelating with Cu²⁺. Therefore, how to co-deliver DSF and Cu²⁺ to tumor tissues and generate a smart response to the tumor microenvironment (TME) are the focus of repurposing DSF for the effective treatment of cancer. Herein, we fabricated facilely a smart nanosystem by coating tannic acid (TA) and Cu²⁺ network on DSF, denoted as DSF@TA-Cu, which responses well to TME and forms CuET complex in situ. In such a way, besides the chemotherapy effect of CuET, the anticancer efficacy of the resulting nano-prodrug can further be augmented by a continuous Fenton-like reaction. We then tested the cytotoxicity DSF@TA-Cu with normal and cancerous cell lines. Finally, by constructing mitochondria-targeted nanoprobes, we monitored the changes in mitochondrial metabolism and explored the lethal mechanisms in A549 cells. We found that DSF@TA-Cu showed higher toxicity to cancerous cells. By analyzing the fluorescence images and surface-enhanced Raman scattering (SERS) spectra of mitochondria, we found that the DNA damage and the decrease in mitochondrial membrane potential (MMP) were closely related to the generation and accumulation of reactive oxygen species (ROS). Although activated related pathways try to counteract the effects of elevation of ROS, excessive ROS inevitably leads to apoptosis of cancer cells.

Targeting regulated cell death in tumor nanomedicines

Nanomedicines hold great potential in anticancer therapy by modulating the biodistribution of nanomaterials and initiating targeted oxidative stress damage, but they are also limited by the inherent self-protection mechanism and the evolutionary treatment resistance of cancer cells. New emerging explorations of regulated cell death (RCD), including processes related to autophagy, ferroptosis, pyroptosis, and necroptosis, substantially contribute to the augmented therapeutic efficiency of tumors by increasing the sensitivity of cancer cells to apoptosis. Herein, paradigmatic studies of RCD-mediated synergistic tumor nanotherapeutics are introduced, such as regulating autophagy-enhanced photodynamic therapy (PDT), targeting ferroptosis-sensitized sonodynamic therapy (SDT), inducing necroptosis-augmented photothermal therapy (PTT), and initiating pyroptosis-collaborative chemodynamic therapy (CDT), and the coordination mechanisms are discussed in detail. Multiangle analyses addressing the present challenges and upcoming prospects of RCD-based nanomedicines have also been highlighted and prospected for their further strengthening and the broadening of their application scope. It is believed that up-and-coming coadjutant therapeutic methodologies based on RCDs will considerably impact precision nanomedicine for cancer.

Inhibiting autophagy flux and DNA repair of tumor cells to boost radiotherapy of orthotopic glioblastoma

Radio-resistance of glioblastoma (GBM) remains a leading cause of radiotherapy failure because of the protective autophagy induced by X-Ray irradiation and tumor cells' strong capability of repairing damaged DNA. It is of great importance to overcome the radio-resistance for improving the efficacy of radiotherapy. Herein, we report the novel mechanism of core-shell copper selenide coated gold nanoparticles (Au@Cu_2-xSe NPs) inhibiting the protective autophagy and DNA repair of tumor cells to drastically boost the radiotherapy efficacy of glioblastoma. We reveal that the core-shell Au@Cu_2-xSe NPs can inhibit the autophagy flux by effectively alkalizing lysosomes. They can increase the SQSTM1/p62 protein levels of tumor cells without influencing their mRNA. We also reveal that Au@Cu_2-xSe NPs can increase the ubiquitination of DNA repair protein Rad51, and promote the degradation of Rad51 by proteasomes to prevent the DNA repair. The simultaneous inhibition of protective autophagy and DNA repair significantly suppress the growth of orthotopic GBM by using radiotherapy and our novel Au@Cu_2-xSe NPs. Our work provides a new insight and paradigm to significantly improve the efficacy of radiotherapy by rationally designing theranostic nano-agents to simultaneously inhibit protective autophagy and DNA repair of tumor cells.

Enhanced Cancer Starvation Therapy Based on Glucose Oxidase/3-Methyladenine-Loaded Dendritic Mesoporous OrganoSilicon Nanoparticles

Cell autophagy is a well-known phenomenon in cancer, which limits the efficacy of cancer therapy, especially cancer starvation therapy. Glucose oxidase (GOx), which is considered as an attractive starvation reagent for cancer therapy, can effectively catalyze the conversion of glucose into gluconic acid and hydrogen peroxide (H2O2) in the presence of O2. However, tumor cells adapt to survive by inducing autophagy, limiting the therapy effect. Therefore, anti-cell adaptation via autophagy inhibition could be used as a troubleshooting method to enhance tumor starvation therapy. Herein, we introduce an anti-cell adaptation strategy based on dendritic mesoporous organosilica nanoparticles (DMONs) loaded with GOx and 3-methyladenine (3-MA) (an autophagy inhibition agent) to yield DMON@GOx/3-MA. This formulation can inhibit cell adaptative autophagy after starvation therapy. Our in vitro and in vivo results demonstrate that autophagy inhibition enhances the efficacy of starvation therapy, leading to tumor growth suppression. This anti-cell adaptation strategy will provide a new way to enhance the efficacy of starvation cancer therapy.

NIR-II fluorescence imaging guided tumor-specific NIR-II photothermal therapy enhanced by starvation mediated thermal sensitization strategy

Photothermal therapy (PTT) is hampered by limited light penetration depth and cell thermoresistance induced by over-expressed heat shock proteins (HSPs). Herein, we proposed a tumor-specific enhanced NIR-II PTT through the starvation mediated thermal sensitization strategy. A semiconducting polymer with superior NIR-II fluorescence imaging (FI) performance and NIR-II PTT efficacy was synthesized and encapsulated into folate modified liposomes, together with a glycolysis inhibitor, 2-deoxy-d-glucose (2DG). Upon specifically targeting folate receptors and guidance of NIR-II FI, spatiotemporal 2DG release could be achieved by the trigger of NIR-II photothermal effect. The released 2DG could not only deplete the energy supply of tumor cells by inhibiting tumor anaerobic glycolysis, but also decrease the ATP levels and hamper the production of HSPs, ultimately enhancing the tumor thermal sensitivity toward PTT. Owing to the sensitization effect of 2DG, tumor cells with overexpressed folate receptors could be significantly damaged by NIR-II PTT with an enhanced therapeutic efficiency. The work provided a promising strategy for specific starvation/NIR-II PTT synergistic therapy towards tumors.

Low-Temperature Photothermal Therapy: Strategies and Applications

Although photothermal therapy (PTT) with the assistance of nanotechnology has been considered as an indispensable strategy in the biomedical field, it still encounters some severe problems that need to be solved. Excessive heat can induce treated cells to develop thermal resistance, and thus, the efficacy of PTT may be dramatically decreased. In the meantime, the uncontrollable diffusion of heat can pose a threat to the surrounding healthy tissues. Recently, low-temperature PTT (also known as mild PTT or mild-temperature PTT) has demonstrated its remarkable capacity of conquering these obstacles and has shown excellent performance in bacterial elimination, wound healing, and cancer treatments. Herein, we summarize the recently proposed strategies for achieving low-temperature PTT based on nanomaterials and introduce the synthesis, characteristics, and applications of these nanoplatforms. Additionally, the combination of PTT and other therapeutic modalities for defeating cancers and the synergistic cancer therapeutic effect of the combined treatments are discussed. Finally, the current limitations and future directions are proposed for inspiring more researchers to make contributions to promoting low-temperature PTT toward more successful preclinical and clinical disease treatments.

Near-infrared Zn-doped Cu2S quantum dots: an ultrasmall theranostic agent for tumor cell imaging and chemodynamic therapy

Theranostic agents that integrated chemodynamic therapy (CDT) and imaging functions have great potential application in personalized cancer therapy. However, most theranostic agents were fabricated by chemically coupling two or more independent functional units with diagnostic or therapeutic capabilities, and therefore have a large size. To date, one-step synthesis of unmodified ultrasmall quantum dots (QDs) integrating CDT and fluorescence imaging capabilities remains a challenge. Herein, we reported a simple one-step synthesis method of ultrasmall (2.46 nm) Zn-doped Cu₂S (Zn:Cu₂S) QDs with inherent properties of both high CDT activity and near-infrared fluorescence imaging capability. The fluorescence of Cu₂S QDs was significantly enhanced approximately tenfold after Zn doping due to the compensation of defects. In vitro and in vivo experiments demonstrated that the Zn:Cu₂S QDs could specifically and significantly inhibit the cancer cell growth (inhibition rate exceeded 65%) without damaging the normal cells. Furthermore, the CDT mechanism study suggested that a Fenton-like reaction occurred after the Zn:Cu₂S QDs entered the tumor cells, inducing apoptosis via the mitochondrial signaling pathway, and activating the production of reactive oxygen species (ROS) and autophagy to selectively eliminate tumor cells to achieve CDT. This work proposed a simple one-step synthesis of unmodified ultrasmall QDs with fluorescence imaging and CDT, which provides a promising strategy for QDs to act as multi-functional theranostic agents.