A nanotherapeutic strategy to overcome chemotherapeutic resistance of cancer stem-like cells

Stemness regulation in prostate cancer: prostate cancer stem cells and targeted therapy

BACKGROUND

Increasing evidence indicates that cancer stem cells (CSCs) and cancer stem-like cells form a special subpopulation of cells that are ubiquitous in tumors. These cells exhibit similar characteristics to those of normal stem cells in tissues; moreover, they are capable of self-renewal and differentiation, as well as high tumorigenicity and drug resistance. In prostate cancer (PCa), it is difficult to kill these cells using androgen signaling inhibitors and chemotherapy drugs. Consequently, the residual prostate cancer stem cells (PCSCs) mediate tumor recurrence and progression.

OBJECTIVE

This review aims to provide a comprehensive and up-to-date overview of PCSCs, with a particular emphasis on potential therapeutic strategies targeting these cells.

METHODS

After searching in PubMed and Embase databases using 'prostate cancer' and 'cancer stem cells' as keywords, studies related were compiled and examined.

RESULTS

In this review, we detail the origin and characteristics of PCSCs, introduce the regulatory pathways closely related to CSC survival and stemness maintenance, and discuss the link between epithelial-mesenchymal transition, tumor microenvironment and tumor stemness. Furthermore, we introduce the currently available therapeutic strategies targeting CSCs, including signaling pathway inhibitors, anti-apoptotic protein inhibitors, microRNAs, nanomedicine, and immunotherapy. Lastly, we summarize the limitations of current CSC research and mention future research directions.

CONCLUSION

A deeper understanding of the regulatory network and molecular markers of PCSCs could facilitate the development of novel therapeutic strategies targeting these cells. Previous preclinical studies have demonstrated the potential of this treatment approach. In the future, this may offer alternative treatment options for PCa patients.

Nanotherapeutic strategies exploiting biological traits of cancer stem cells

Cancer stem cells (CSCs) represent a distinct subpopulation of cancer cells that orchestrate cancer initiation, progression, metastasis, and therapeutic resistance. Despite advances in conventional therapies, the persistence of CSCs remains a major obstacle to achieving cancer eradication. Nanomedicine-based approaches have emerged for precise CSC targeting and elimination, offering unique advantages in overcoming the limitations of traditional treatments. This review systematically analyzes recent developments in nanomedicine for CSC-targeted therapy, emphasizing innovative nanomaterial designs addressing CSC-specific challenges. We first provide a detailed examination of CSC biology, focusing on their surface markers, signaling networks, microenvironmental interactions, and metabolic signatures. On this basis, we critically evaluate cutting-edge nanomaterial engineering designed to exploit these CSC traits, including stimuli-responsive nanodrugs, nanocarriers for drug delivery, and multifunctional nanoplatforms capable of generating localized hyperthermia or reactive oxygen species. These sophisticated nanotherapeutic approaches enhance selectivity and efficacy in CSC elimination, potentially circumventing drug resistance and cancer recurrence. Finally, we present an in-depth analysis of current challenges in translating nanomedicine-based CSC-targeted therapies from bench to bedside, offering critical insights into future research directions and clinical implementation. This review aims to provide a comprehensive framework for understanding the intersection of nanomedicine and CSC biology, contributing to more effective cancer treatment modalities.

Photothermal treatment of prostate tumor with micellar indocyanine green and napabucasin to co-ablate cancer cells and cancer stem cells

Advanced prostate cancer is hassled by relapse and metastasis that are closely associated with cancer stem cells (CSCs). Here, we present micellar indocyanine green and napabucasin (mICG-Nap) that co-ablates cancer cells and CSCs via photothermal therapy (PTT) for the treatment of prostate tumor. mICG-Nap with stable loading of both drugs and favorable size effectively reduced CSC population in RM1-PSMA murine prostate cancer cells and inhibited tumor spheroid formation. mICG-Nap showed an enhanced photothermal effect compared with free ICG and eliminated tumor spheroids under near-infrared (NIR) irradiation. The efficacy of mICG-Nap was further enhanced by decorating with Acupa ligand, which targets to RM1-PSMA cells and tumors via PSMA receptor. The enhanced tumor cell uptake of Acupa-mICG-Nap led to significant survival benefits in both subcutaneous RM1-PSMA tumor models and postoperative models. The tumor analyses demonstrated clear downregulation of CSC-related biomarkers such as OCT4, SOX2, CD133 and pSTAT3 as well as PSMA by Acupa-mICG-Nap. Rational formulated micellar indocyanine green and napabucasin plus NIR appears as an appealing strategy to co-ablate cancer cells and CSCs with rapid tumor de-bulking yet no recurrence.

Smart hydrogel: A new platform for cancer therapy

Cancer is a significant contributor to mortality worldwide, posing a significant threat to human life and health. The unique bioactivity, ability to precisely control drug release, and minimally invasive properties of hydrogels are indispensable attributes that facilitate optimal performance in cancer therapy. However, conventional hydrogels lack the ability to dynamically respond to changes in the surrounding environment, withstand drastic changes in the microenvironment, and trigger drug release on demand. Therefore, this review focuses on smart-responsive hydrogels that are capable of adapting and responding to external stimuli. We comprehensively summarize the raw materials, preparation, and cross-linking mechanisms of smart hydrogels derived from natural and synthetic materials, elucidate the response principles of various smart-responsive hydrogels according to different stimulation sources. Further, we systematically illustrate the important role played by hydrogels in modern cancer therapies within the context of therapeutic principles. Meanwhile, the smart hydrogel that uses machine learning to design precise drug delivery has shown great prospects in cancer therapy. Finally, we present the outlook on future developments and make suggestions for future related work. It is anticipated that this review will promote the practical application of smart hydrogels in cancer therapy and contribute to the advancement of medical treatment.

Advances in nanoplatform-based multimodal combination therapy activating STING pathway for enhanced anti-tumor immunotherapy

Activation of the cyclic GMP-AMP synthase(cGAS)-stimulator of interferon genes (STING) has great potential to promote antitumor immunity. As a major effector of the cell to sense and respond to the aberrant presence of cytoplasmic double-stranded DNA (dsDNA), inducing the expression and secretion of type I interferons (IFN) and STING, cGAS-STING signaling pathway establishes an effective natural immune response, which is one of the fundamental mechanisms of host defense in organisms. In addition to the release of heterologous DNA due to pathogen invasion and replication, mitochondrial damage and massive cell death can also cause abnormal leakage of the body's own dsDNA, which is then recognized by the DNA receptor cGAS and activates the cGAS-STING signaling pathway. However, small molecule STING agonists suffer from rapid excretion, low bioavailability, non-specificity and adverse effects, which limits their therapeutic efficacy and in vivo application. Various types of nano-delivery systems, on the other hand, make use of the different unique structures and surface modifications of nanoparticles to circumvent the defects of small molecule STING agonists such as fast metabolism and low bioavailability. Also, the nanoparticles are precisely directed to the focal site, with their own appropriate particle size combined with the characteristics of passive or active targeting. Herein, combined with the cGAS-STING pathway to activate the immune system and kill tumor tissues directly or indirectly, which help maximize the use of the functions of chemotherapy, photothermal therapy(PTT), chemodynamic therapy(CDT), and radiotherapy(RT). In this review, we will discuss the mechanism of action of the cGAS-STING pathway and introduce nanoparticle-mediated tumor combination therapy based on the STING pathway. Collectively, the effective multimodal nanoplatform, which can activate cGAS-STING pathway for enhanced anti-tumor immunotherapy, has promising avenue clinical applications for cancer treatment.

A Light-Driven Electrochromic Materials-Based Nanomotor for H2S-Controlled Drug Release in Synergistic Cancer Chemotherapy Immunotherapy

Nanomotors hold tremendous potential for drug delivery. However, current nanomotors face limitations that compromise efficiency of drug utilization, including the use of inorganic materials with suboptimal soft interface and biocompatibility, uncontrollable drug release, insufficient directional control, and slow movement speeds. Herein, we present a novel near-infrared (NIR) light-driven porous unsymmetric nanomotor with ultrafast motion, which utilizes hydrogen sulfide (H2S)-responsive cationic organic π-electron structure-based electrochromic material (F12+) for the payload and controlled release of anionic anticancer drugs, enabling synergistic cancer chemotherapy and immunotherapy. We demonstrate that the nanomotor can precisely target tumors driven by thermophoresis, tumor-targeting peptide (RGD), and H2S (highly expressed in tumors and acted as chemoattractants), which induces chemotactic behavior to guide nanomotors into tumors. Once in the tumors, the cationic F12+ is reduced to the diene F2 upon reaction with H2S, activating the nanomotor's NIR fluorescence for real-time monitoring of drug delivery and release in vivo. Upon exposure to H2S, the nanomotor undergoes disassembly due to the disruption of electrostatic interactions between the anionic anticancer drugs and the cationic F12+, leading to the precise and controlled drug release, ensuring uniform distribution across the tumor. This innovative strategy would open avenues for delivering mRNA vaccines or other anionic drugs.

Oxygen-regulated enzymatic nanoplatform for synchronous intervention in glycolysis and oxidative phosphorylation to augment antitumor therapy

Tumor cells typically undergo metabolic reprogramming to obtain substantial energy via glycolysis and oxidative phosphorylation (OXPHOS). Intervening in this reprogramming is expected to have therapeutic effects, but simultaneous intervention in these two metabolic pathways is challenging. Herein, we developed an "open-source and throttling" oxygen (O₂) modulation strategy by which we can simultaneously intervene in these two metabolic pathways. Our O₂ modulation nanoplatform (denoted as OAGO) is fabricated via the self-assembly of glucose oxidase (GOx) and oligomycin A (OA) and is coated with bacterial outer membrane vesicles (OMVs). OAGO elicits simultaneous GOx-mediated inhibition of glycolysis and OA-induced inhibition of OXPHOS. The resulting production of GOx-catalyzed hydrogen peroxide leads to oxidative stress, which exacerbates the inhibition of mitochondrial function. Meanwhile, OA reduces intratumoral O₂ consumption (i.e., the "throttling" strategy), and OMVs increase the tumor blood O₂ level (i.e., the "open-source" strategy). This results in an increase in O₂ levels for GOx catalysis, thereby exacerbating energy consumption. In addition, OMVs increase intratumoral OAGO accumulation and enable photothermal therapy in the 4T1 mouse model, which also raises the tumor blood O₂ level and benefits GOx catalysis. This synchronous intervention in two metabolic pathways alongside O₂ modulation constitutes a promising approach for efficient antitumor therapy.

Programmable hierarchical hydrogel dressing for sequential release of growth factor and DNase to accelerate diabetic wound healing

Dysregulation of growth factor expression causes impaired healing of diabetic foot ulcer (DFU). Platelet-derived growth factor (PDGF)-containing gel has been clinically applied for topical treatment of DFU. Recruitment of neutrophils stimulated by PDGF favors the wound healing of DFU. However, overactivation of neutrophils induced by hyperglycemia causes massive generation and long-term persistence of neutrophil extracellular traps (NETs), ultimately leading to unexpected skin damage and delayed wound repair. Here, we engineer a hierarchically-assembled hydrogel to achieve local release of the growth factor, PDGF-BB and the NET scavenger, deoxyribonuclease (DNase) I with distinct kinetics for enhanced healing of DFU. The hydrogel is constructed by crosslinking of anti-bacterial quaternized chitosan and hypochlorite-degradable nanogel via a copper-free click reaction, in which PDGF-BB is loaded in the hydrogel matrix while DNase I is encapsulated in the inner nanogel. Programmable release of combinatorial therapeutics is implemented by the hydrogel in response to the wound microenvironment. We show that the hierarchical hydrogel co-loaded with PDGF-BB and DNase I promotes neutrophil recruitment, increases endothelial cell migration, degrades excess NETs, and prevents wound infection for accelerating the wound closure in the diabetic mouse wound models.

Mitigating Doxorubicin-Induced Cardiotoxicity and Enhancing Anti-Tumor Efficacy with a Metformin-Integrated Self-Assembled Nanomedicine

Doxorubicin (Dox) is a potent chemotherapeutic agent commonly used in cancer treatment. However, cardiotoxicity severely limited its clinical application. To address this challenge, a novel self-assembled nanomedicine platform, PMDDH, is developed for the co-delivery of Dox and metformin, an antidiabetic drug with cardioprotective and anti-tumor properties. PMDDH integrates metformin into a polyethyleneimine-based bioactive excipient (PMet), with Dox intercalated into double-stranded DNA and a hyaluronic acid (HA) coating to enhance tumor targeting. The PMDDH significantly improves the pharmacokinetics and tumor-targeting capabilities of Dox, while metformin enhances the drug's anti-tumor activity by downregulating programmed cell death ligand 1 (PD-L1) and activating the AMP-activated protein kinase (AMPK) signaling pathway. Additionally, the DNA component stimulates the cyclic GMP-AMP synthase-stimulator of interferon genes (cGAS-STING) pathway, which synergizes with Dox-induced immunogenic cell death (ICD) to promote a robust anti-tumor immune response. PMDDH markedly reduces Dox-induced cardiotoxicity by preserving mitochondrial function, reducing reactive oxygen species (ROS) production, and inducing protective autophagy in cardiomyocytes. These findings position PMDDH as a promising dual-function nanomedicine that enhances the anti-tumor efficacy of Dox while minimizing its systemic toxicity, offering a safer and more effective alternative for cancer therapy.

Advances in nanocarriers for targeted drug delivery and controlled drug release

Nanocarrier-based drug delivery systems (nDDSs) present significant opportunities for improving disease treatment, offering advantages in drug encapsulation, solubilization, stability enhancement, and optimized pharmacokinetics and biodistribution. nDDSs, comprising lipid, polymeric, protein, and inorganic nanovehicles, can be guided by or respond to biological cues for precise disease treatment and management. Equipping nanocarriers with tissue/cell-targeted ligands enables effective navigation in complex environments, while functionalization with stimuli-responsive moieties facilitates site-specific controlled release. These strategies enhance drug delivery efficiency, augment therapeutic efficacy, and reduce side effects. This article reviews recent strategies and ongoing advancements in nDDSs for targeted drug delivery and controlled release, examining lesion-targeted nanomedicines through surface modification with small molecules, peptides, antibodies, carbohydrates, or cell membranes, and controlled-release nanocarriers responding to endogenous signals such as pH, redox conditions, enzymes, or external triggers like light, temperature, and magnetism. The article also discusses perspectives on future developments.

Smart on-demand drug release strategies for cancer combination therapy

In cancer therapy, enhancing therapeutic indices and patient compliance has been a central focus in recent drug delivery technology development. However, achieving a delicate balance between improving anti-tumor efficacy and minimizing toxicity to normal tissues remains a significant challenge. With the advent of smart on-demand drug release strategies, new opportunities have emerged. These strategies represent a promising approach to drug delivery, enabling precise control over the release of therapeutic agents in a programmed and spatiotemporal manner. Recent studies have focused on designing delivery systems capable of releasing multiple therapeutic agents sequentially, while achieving spatial resolution in vivo. Smart on-demand drug release strategies have demonstrated considerable potential in tumor combination therapy for achieving precision drug delivery and controlled release by responding to specific physiological signals or external physical stimuli in the tumor microenvironment. These strategies not only improve tumor targeting and reduce toxicity to healthy tissues but also enable sequential release in combination therapy, allowing multiple drugs to be released in a specific spatiotemporal order to enhance synergistic treatment effects. In this paper, we systematically reviewed the current research progress of smart on-demand drug release drug delivery strategies in anti-tumor combination therapy. We highlighted representative integrated drug delivery systems and discussed the challenges associated with their clinical application. Additionally, potential future research directions are proposed to further advance this promising field.

Self-Assembled Triple-Targeted Radiosensitizer Enhances Hypoxic Tumor Targeting and Radio-Immunotherapy Efficacy

Targeted delivery of radiosensitizers and real-time monitoring of hypoxia are crucial for overcoming radiotherapy resistance in hypoxic tumors. Here, we report A-Cy-Ni-RGD, a triple-targeted nitroimidazole (Ni)-linked radiosensitizer that self-assembles into nanoparticles (A-Cy-Ni-RGD NPs) for bimodal near-infrared fluorescence (NIR FL) and photoacoustic (PA) imaging-guided radio-immunotherapy. A-Cy-Ni-RGD NPs specifically accumulate in αvβ3-positive tumors, where they are hydrolyzed by carboxylesterase to form Cy-Ni-RGD NPs, with enhanced FL at 710 nm and dual PA signals at 680 and 730 nm. Under hypoxic conditions, nitroreductase (NTR) further reduces these NPs, covalently labeling endogenous proteins and increasing NP size. This process partially alleviates aggregation-caused quenching effect, increasing the FL710 signal and decreasing the PA730 signal, enabling real-time tracking of tumor-specific delivery and hypoxia. Following low-dose X-ray irradiation (2 Gy), elevated NTR expression promotes further Cy-Ni-RGD NPs reduction, enhancing proteins labeling and causing DNA damage. Moreover, radiosensitization with A-Cy-Ni-RGD NPs triggers robust immunogenic cell death, stimulating antitumor immunity that inhibits tumor growth and metastasis, significantly prolonging survival in mice with orthotopic 4T1 tumors. This work underscores the potential of self-assembling, triple-targeted radiotheranostic agents for improving tumor targeting, imaging, and radiotherapy efficacy in hypoxic tumors.

Tumor Microenvironment-Responsive Polymer Delivery Platforms for Cancer Therapy

Most chemotherapeutic and bioimaging agents struggle with inadequate bioavailability, primarily due to their limited biocompatibility and lack of specificity in targeting, leading to low or decreased anticancer efficacy and inaccurate imaging. To surmount these obstacles, the development of stimuli-responsive polymer delivery platforms, predominantly leveraging the tumor microenvironment (TME), has emerged as a promising strategy. Therapeutic and diagnostic agents can be released controllably at the tumor site by virtue of the bond cleavage or hydrophobic to hydrophilic transformation of TME-sensitive linkages in TME-responsive systems, thus augmenting cancer treatment and imaging precision, while simultaneously attenuating the damage to healthy tissues and false imaging signals caused by non-specific drug leakage. In this comprehensive review, we scrutinize recent studies of TME-responsive polymer delivery platforms, encompassing pH-, ROS-, GSH-, enzyme-, and hypoxia-responsive vectors, significantly from the perspective of their molecular design and responsive mechanism, and further summarizing their bio-application in drug delivery and diagnostic imaging. Moreover, this review encapsulates the critical challenges and offers an insightful perspective on the future prospects of TME-responsive polymer delivery platforms in terms of molecular and vector design.

Sequential drug release nanocomposites for synergistic therapy in disease treatment

Time-sequenced drug release, or sequential drug release, represents a pivotal strategy in the synergistic treatment of diseases using nanocomposites. Achieving this requires the rational integration of multiple therapeutic agents within a single nanocomposite, coupled with precise time-controlled release mechanisms. These nanocomposites offer many advantages, including enhanced therapeutic synergy, reduced side effects, attenuated adverse interactions, improved stability and optimized drug utilization. Consequently, research in the field of drug delivery and synergistic therapy has become increasingly important. Currently, sequential drug release research is still in the data collection and basic research stages, and its potential has not yet been fully explored. Although prior studies have explored the sequential drug release strategy in various contexts, a comprehensive review of the underlying mechanisms and their applications in nanocomposites remains scarce. This review categorizes different types of sequential drug release strategies and summarizes diverse nanocomposites, focusing on both physical approaches driven by structural variations and chemical methods based on stimulus-responsive mechanisms. Furthermore, we highlight the major applications of sequential drug release strategies in the treatment of various diseases and detail their therapeutic efficacy. Finally, emerging trends and challenges in advancing sequential drug release strategies based on nanocomposites for disease treatment are also discussed.

Advances in controlled release drug delivery systems based on nanomaterials in lung cancer therapy: A review

Lung cancer is one of the most common malignant tumors, with the highest morbidity and mortality rates. Currently, significant progress has been made in the treatment of lung cancer, which has effectively improved the overall prognosis of patients, but there are still many problems, such as tumor recurrence, drug resistance, and serious complications. With the rapid development of nanotechnology in the field of medicine, it breaks through the inherent limitations of traditional cancer treatments and shows great potential in tumor treatment. To address the drawbacks of traditional therapeutic means, nanodrug delivery systems can release drugs under specific conditions, thus realizing tumor-targeted drug delivery, which improves the antitumor effect of drugs. In this paper, we review the current treatments for lung cancer and further discuss the advantages and common carriers of nanodrug delivery systems. We also summarize the latest research progress of nanotargeted drug delivery systems in the field of lung cancer therapy, discuss the problems faced in their clinical translation, and look forward to future development opportunities and directions.

Implantable Microneedles Loaded with Nanoparticles Surface Engineered Escherichia coli for Efficient Eradication of Triple-Negative Breast Cancer Stem Cells

Eliminating cancer stem cells (CSCs) is essential for the effective treatment of triple-negative breast cancer (TNBC). This study synthesized Au@cerium-zinc composite core@shell nanoparticles (Au@Zn/CeO) that were subsequently conjugated with Escherichia coli (E. coli) to create the engineered bacterium AZCE, which was then combined with microneedle carriers and freeze-dried to obtain AZCE-MN. Upon implantation into TNBC tumors, the inherent properties of E. coli facilitate AZCE to penetrate the extracellular matrix and break through the basement membrane, enabling effective delivery of AZC to CSCs-enriched regions deep within the tumor. The released Zn2+ induces mitochondrial dysfunction and amplifies reactive oxygen species (ROS) production. The redox cycling between Ce3+/Ce4+ effectively depleted glutathione, which further increased ROS generation. Under near-infrared laser irradiation, Au nanorods initiated photothermal therapy, effectively ablating CSCs while amplifying catalytic reactions and ionic effects. This microneedle-mediated engineered bacteria delivery improved nanodrug penetration in tumor tissues, providing new insights for TNBC clinical treatment.

Hyaluronic acid-functionalized ruthenium photothermal nanoenzyme for enhancing osteosarcoma chemotherapy: Cascade targeting and bidirectional modulation of drug resistance

Insufficient drug delivery efficiency in vivo and robust drug resistance are two major factors to induce suboptimal efficacy in chemotherapy of osteosarcoma (OS). To address these challenges, we developed polysaccharide hyaluronic acid (HA)-functionalized ruthenium nanoaggregates (Ru NAs) to enhance the chemotherapy of doxorubicin (DOX) for OS. These NAs, comprising Ru nanoparticles (NPs) and alendronate-modified HA (HA-ALN), effectively load DOX, resulting in DOX@Ru-HA-ALN NAs. The combination of HA and ALN in NAs ensures outstanding cascade targeting towards tumor-invaded bone tissues and CD44-overexpressing tumor cells, maximizing therapeutic efficacy while minimizing off-target effects. Concurrently, the Ru NPs in NAs function as "smart" photoenzymatic agent to not only in situ relieve hypoxia of OS via the catalysis of overexpressed H2O2 to produce O2, but also generate mild photothermal effect under 808-nm laser irradiation. They can bidirectionally overcome drug resistance of DOX via downregulation of resistance-related factors including multi-drug resistant associate protein, P-glycoprotein, heat shock factor 1, etc. The integration of cascade targeting with bidirectional modulation of drug resistance positions Ru-HA-ALN NAs to substantially enhance DOX chemotherapy for OS. Therefore, the present work highlights the potential of polysaccharide-functionalized nanomaterials in advancing tumor chemotherapy by addressing challenges of both delivery efficiency and drug resistance.

Cascade specific endogenous Fe3+ interference and in situ catalysis for tumor therapy with stemness suppression

Cancer stem-like cells (CSCs), featuring high tumorigenicity and invasiveness, are one of the critical factors leading to the failure of clinical cancer treatment such as metastasis and recurrence. However, current strategies suffer from the low stemness-inhibiting efficacy on CSCs by conventional molecular agents and the poor lethal effects against bulk tumor cells. Here we engineer a coordination nanomedicine by 2,5-dihydroxyterephthalic acid (DHT) complexing zinc ions (Zn2+) as a double-effect nanodisrupter of tumor iron (Fe) and redox homeostasis for catalysis-boosted tumor therapy with stemness inhibition. Taking advantage of the much higher binding force of DHT toward Fe3+, this nanomedicine can specifically chelate endogenous Fe3+ into its nanostructure and release Zn2+, and the in situ formed hexacoordinated Fe-DHT conformation is of much enhanced reducibility in order to promote reactive oxygen species (ROS) production in tumors. The nanomedicine-mediated Fe depletion and ROS generation collectively induce CSC differentiation via downregulating the Wnt signaling and inducing forkhead box O3 (FoxO3) activation, respectively. Notably, the combined tumor-selective ROS generation and Zn2+-induced antioxidation dysfunction potently trigger intratumoral oxidative damage leading to both cellular apoptosis and ferroptosis. This nanomedicine, capable of synchronously treating CSCs and bulk tumor cells, has been demonstrated to effectively inhibit the growth, postoperative recurrence and metastasis of orthotopic triple-negative breast tumors in vivo, offering an encouraging candidate of cancer therapeutic agents for treating CSCs-enriched malignancy.

Harnessing nanotechnology for cancer treatment

Nanotechnology has become a groundbreaking innovation force in cancer therapy, offering innovative solutions to the limitations of conventional treatments such as chemotherapy and radiation. By manipulating materials at the nanoscale, researchers have developed nanocarriers capable of targeted drug delivery, improving therapeutic efficacy while reducing systemic toxicity. Nanoparticles like liposomes, dendrimers, and polymeric nanomaterials have shown significant promise in delivering chemotherapeutic agents directly to tumor sites, enhancing drug bioavailability and minimizing damage to healthy tissues. In addition to drug delivery, with the utilization of tools such as quantum dots and nanosensors that enables more precise identification of cancer biomarkers, nanotechnology is also playing a pivotal role in early cancer detection and diagnosis. Furthermore, nanotechnology-based therapeutic strategies, including photothermal therapy, gene therapy and immunotherapy are offering novel ways to combat cancer by selectively targeting tumor cells and enhancing the immune response. Nevertheless, despite these progressions, obstacles still persist, particularly in the clinical translation of these technologies. Issues such as nanoparticle toxicity, biocompatibility, and the complexity of regulatory approval hinder the widespread adoption of nanomedicine in oncology. This review discusses different applications of nanotechnology in cancer therapy, highlighting its potential and the hurdles to its clinical implementation. Future research needs to concentrate on addressing these obstacles to unlock the full potential of nanotechnology in providing personalized, effective, and minimally invasive cancer treatments.

Enhanced targeted treatment of cervical cancer using nanoparticle-based doxycycline delivery system

This study investigates a nanoparticle-based doxycycline (DOX) delivery system targeting cervical cancer cells via the CD44 receptor. Molecular docking revealed a strong binding affinity between hyaluronic acid (HA) and CD44 (binding energy: -7.2 kJ/mol). Characterization of the HA-Chitosan nanoparticles showed a particle size of 284.6 nm, a zeta potential of 16.9 mV, and a polydispersity index of 0.314, with SEM confirming smooth surface morphology. The encapsulation efficiency of DOX-loaded nanoparticles was 89.32%, exhibiting a sustained release profile, with 67.45% released over 72 h in acidic conditions (pH 5.5). Cytotoxicity assays demonstrated a significant reduction in HeLa cell viability to 22% at 72 h, compared to 67% in normal HEK cells. Stability tests confirmed the maintenance of nanoparticle integrity and a consistent drug release profile over three months. Cell migration was reduced by 45%, and RT-PCR analysis revealed a 53% downregulation of TNF-α expression, suggesting effective targeting of inflammatory pathways. These results underscore the potential of HA-Chitosan-based DOX nanoparticles in improving cervical cancer treatment through enhanced targeted delivery and inhibition of tumor-promoting mechanisms.

Dual-phase nanoscissors disrupt vasculature-breast cancer stem cell crosstalk for breast cancer treatment

Clinical treatment effects of breast cancer are heavily frustrated by the malignant crosstalk between tumor vasculature and breast cancer stem cells (BCSCs). This study introduces a two-phase therapeutic strategy targeting the interplay between tumor vasculature and BCSCs to overcome this challenge. Here, we an FLG/ZnPc nanoscissor, which combines mild photodynamic therapy (PDT) to generate reactive oxygen species (ROS) with vascular normalization therapy (VNT) to break the crosstalk between tumor vasculature and BCSCs. In the first phase, our approach breaks the vascular niche that supports BCSCs by restoring tumor vascular function and promoting ROS-induced BCSCs differentiation into less malignant forms, enhancing treatment sensitivity. The second phase employs high-impact photothermal therapy (PTT) to ablate tumor masses. This integrated "mild PDT-PTT" approach aims to reduce tumor growth and metastasis, offering a comprehensive strategy for effective breast cancer management.

Notch Pathway Deactivation Sensitizes Breast Cancer Stem Cells toward Chemotherapy Using NIR Light-Responsive Nanoparticles

Chemotherapy remains a major therapeutic approach to cancer treatment. However, its effectiveness can be compromised by the heterogeneity of a solid tumor, in which different cancer cell populations display varied responses to chemotherapy. Such an intratumor heterogeneous structure is maintained by the cancer stem-like cells (CSCs) with inherent capacities for self-renewal and differentiation, giving rise to diverse cell populations. To address this, we proposed a combinational strategy in which tumor lesion-targeted Notch signaling regulation was achieved to disrupt CSC-mediated cancer heterogeneity, thereby sensitizing solid tumors toward paclitaxel (PTX). Specifically, gamma-secretase inhibitor LY-411,575 was co-delivered with PTX using a near-infrared (NIR) light-controlled drug delivery system to realize targeted ablation of both differentiated cancer cells and undifferentiated CSCs. By enabling precise regulation of the Notch pathway at the tumor site through NIR light, we observed significantly elevated efficacy of chemotherapy and notable prevention of postsurgical tumor relapse while minimizing systemic side effects. The devised strategy shows promise in addressing the nonspecific inhibition of stemness across various organs, a challenge that hampers the clinical translation of gamma-secretase inhibitors in cancer therapy.

Recent advances in reactive oxygen species (ROS)-responsive drug delivery systems for photodynamic therapy of cancer

Reactive oxygen species (ROS)-responsive drug delivery systems (DDSs) have garnered significant attention in cancer research because of their potential for precise spatiotemporal drug release tailored to high ROS levels within tumors. Despite the challenges posed by ROS distribution heterogeneity and endogenous supply constraints, this review highlights the strategic alliance of ROS-responsive DDSs with photodynamic therapy (PDT), enabling selective drug delivery and leveraging PDT-induced ROS for enhanced therapeutic efficacy. This review delves into the biological importance of ROS in cancer progression and treatment. We elucidate in detail the operational mechanisms of ROS-responsive linkers, including thioether, thioketal, selenide, diselencide, telluride and aryl boronic acids/esters, as well as the latest developments in ROS-responsive nanomedicines that integrate with PDT strategies. These insights are intended to inspire the design of innovative ROS-responsive nanocarriers for enhanced cancer PDT.

Self-assembled aldehyde dehydrogenase-activatable nano-prodrug for cancer stem cell-enriched tumor detection and treatment

Cancer stem cells, characterized by high tumorigenicity and drug-resistance, are often responsible for tumor progression and metastasis. Aldehyde dehydrogenases, often overexpressed in cancer stem cells enriched tumors, present a potential target for specific anti-cancer stem cells treatment. In this study, we report a self-assembled nano-prodrug composed of aldehyde dehydrogenases activatable photosensitizer and disulfide-linked all-trans retinoic acid for diagnosis and targeted treatment of cancer stem cells enriched tumors. The disulfide-linked all-trans retinoic acid can load with photosensitizer and self-assemble into a stable nano-prodrug, which can be disassembled into all-trans retinoic acid and photosensitizer in cancer stem cells by high level of glutathione. As for the released photosensitizer, overexpressed aldehyde dehydrogenase catalyzes the oxidation of aldehydes to carboxyl under cancer stem cells enriched microenvironment, activating the generation of reactive oxygen species and fluorescence emission. This generation of reactive oxygen species leads to direct killing of cancer stem cells and is accompanied by a noticeable fluorescence enhancement for real-time monitoring of the cancer stem cells enriched microenvironment. Moreover, the released all-trans retinoic acid, as a differentiation agent, reduce the cancer stem cells stemness and improve the cancer stem cells enriched microenvironment, offering a synergistic effect for enhanced anti-cancer stem cells treatment of photosensitizer in inhibition of in vivo tumor growth and metastasis.

Multifunctional nano co-delivery system for efficiently eliminating neuroblastoma by overcoming cancer heterogeneity

The high heterogeneity of neuroblastoma (NB) is currently the main challenge in clinical treatment, impeding the complete eradication of the tumor through monotherapy alone. In this study, we propose a combination strategy using a targeted nano co-delivery system (ADRF@Ag2Se) comprising phototheranostic agents, differentiation inducers and chemotherapy drugs for sequential therapy of NB. Upon intravenous injection, ADRF@Ag2Se demonstrates effective tumor targeting by the specific binding of AF7P to MMP14, which is overexpressed on the surface of NB cells. Subsequent implementation of local photothermal therapy (PTT) leverages the robust photothermal conversion capabilities of the amphiphilic photothermal reagent PF. This is followed by the temperature-triggered release of differentiation-inducing agent 13-cis-retinoic acid and chemo-drug doxorubicin to synergistically eliminate the residual lesions. This nanotherapeutic strategy facilitatesin vivotargeted delivery and PTT under the supervision of NIR-II fluorescence, and it also enhances the chemotherapeutic response through differentiation induction of poorly differentiated cancer cells. In the NB tumor model, this co-delivery strategy effectively inhibited tumor growth and significantly prolonged the survival of the mice.

Stabilized Cell Membrane-Derived Vesicles by Lipid Anchoring for Enhanced Drug Delivery

A cell membrane-derived vesicle (MV) that has cell-mimicking features with characteristic functionalities holds vast appeal for biomimetic nanomedicine and drug delivery but suffers from a major limitation of innate fragility and poor stability. Herein, we report a lipid-anchoring strategy for stabilizing MV for enhanced drug delivery. An array of amphiphilic mono-acyl phosphatidylcholines (MPCs) with specific hydrophobic moieties are synthesized and readily engineered on MV based on their commendable aqueous solubility and efficient membrane insertability. Incorporation of MPCs containing rigid ring structures in the hydrophobic segment demonstrates the potency of stabilizing MV by the combined ordering and condensing effects. The optimized MPC-stabilized MV exhibits prolonged circulation in the bloodstream, elevated accumulation within a tumor, and enhanced therapeutic effects of chemotherapeutic and photothermal drugs. Moreover, doxorubicin-loaded MV, engineered with mono-all-trans retinoyl phosphatidylcholine as an MV stabilizer and a therapeutic prodrug, potently suppresses growth and metastasis of high-stemness tumors.

Multi-stage mechanisms of tumor metastasis and therapeutic strategies

The cascade of metastasis in tumor cells, exhibiting organ-specific tendencies, may occur at numerous phases of the disease and progress under intense evolutionary pressures. Organ-specific metastasis relies on the formation of pre-metastatic niche (PMN), with diverse cell types and complex cell interactions contributing to this concept, adding a new dimension to the traditional metastasis cascade. Prior to metastatic dissemination, as orchestrators of PMN formation, primary tumor-derived extracellular vesicles prepare a fertile microenvironment for the settlement and colonization of circulating tumor cells at distant secondary sites, significantly impacting cancer progression and outcomes. Obviously, solely intervening in cancer metastatic sites passively after macrometastasis is often insufficient. Early prediction of metastasis and holistic, macro-level control represent the future directions in cancer therapy. This review emphasizes the dynamic and intricate systematic alterations that occur as cancer progresses, illustrates the immunological landscape of organ-specific PMN creation, and deepens understanding of treatment modalities pertinent to metastasis, thereby identifying some prognostic and predictive biomarkers favorable to early predict the occurrence of metastasis and design appropriate treatment combinations.

Bioresponsive Immunotherapeutic Materials

The human immune system is an interaction network of biological processes, and its dysfunction is closely associated with a wide array of diseases, such as cancer, infectious diseases, tissue damage, and autoimmune diseases. Manipulation of the immune response network in a desired and controlled fashion has been regarded as a promising strategy for maximizing immunotherapeutic efficacy and minimizing side effects. Integration of "smart" bioresponsive materials with immunoactive agents including small molecules, biomacromolecules, and cells can achieve on-demand release of agents at targeted sites to reduce overdose-related toxicity and alleviate off-target effects. This review highlights the design principles of bioresponsive immunotherapeutic materials and discusses the critical roles of controlled release of immunoactive agents from bioresponsive materials in recruiting, housing, and manipulating immune cells for evoking desired immune responses. Challenges and future directions from the perspective of clinical translation are also discussed.

Glypican-3-targeted macrophages delivering drug-loaded exosomes offer efficient cytotherapy in mouse models of solid tumours

Cytotherapy is a strategy to deliver modified cells to a diseased tissue, but targeting solid tumours remains challenging. Here we design macrophages, harbouring a surface glypican-3-targeting peptide and carrying a cargo to combat solid tumours. The anchored targeting peptide facilitates tumour cell recognition by the engineered macrophages, thus enhancing specific targeting and phagocytosis of tumour cells expressing glypican-3. These macrophages carry a cargo of the TLR7/TLR8 agonist R848 and INCB024360, a selective indoleamine 2,3-dioxygenase 1 (IDO1) inhibitor, wrapped in C16-ceramide-fused outer membrane vesicles (OMV) of Escherichia coli origin (RILO). The OMVs facilitate internalization through caveolin-mediated endocytosis, and to maintain a suitable nanostructure, C16-ceramide induces membrane invagination and exosome generation, leading to the release of cargo-packed RILOs through exosomes. RILO-loaded macrophages exert therapeutic efficacy in mice bearing H22 hepatocellular carcinomas, which express high levels of glypican-3. Overall, we lay down the proof of principle for a cytotherapeutic strategy to target solid tumours and could complement conventional treatment.

Trapped in Cells: A Selective Accumulation Approach for Type-I Photodynamic Ablation of Cancer Stem-like Cells

Aldehyde dehydrogenase (ALDH) is an enzyme responsible for converting aldehyde functional groups into carboxylate metabolites. Elevated ALDH activity is a characteristic feature of cancer stem-like cells (CSCs). As a novel approach to target the CSC trait of overexpressing ALDH, we aimed to utilize ALDH activity for the selective accumulation of a photosensitizer in ALDHHigh CSCs. A novel ALDH substrate photosensitizer, SCHO, with thionylated coumarin and N-ethyl-4-(aminomethyl)benzaldehyde was developed to achieve this goal. Our study demonstrated the efficient metabolism of the aldehyde unit of SCHO into carboxylate, leading to its accumulation in ALDHHigh MDA-MB-231 cells. Importantly, we established the selectivity of SCHO as an ALDHHigh cell photosensitizer as it is not a substrate for ABC transporters. SCHO-based photodynamic therapy triggers apoptosis and pyroptosis in MDA-MB-231 cells and further reduces the characteristics of CSCs. Our study presents a novel strategy to target CSCs by exploiting their cellular metabolism to enhance photosensitizer accumulation, highlighting the potential of photodynamic therapy as a powerful tool for eliminating ALDHHigh CSCs.

The p38/MAPK pathway as a therapeutic target to prevent therapeutic escape of breast cancer stem cells

Cancer stem cells (CSCs) play an important role in metastasis development, tumor recurrence, and treatment resistance, and are essential for the eradication of cancer. Currently, therapies fail to eradicate CSCs due to their therapeutic stress-induced cellular escape, which leads to enhanced aggressive behaviors compared with CSCs that have never been treated. However, the underlying mechanisms regulating the therapeutic escape remain unknown. To this end, we established a model to isolate the therapeutic escaped CSCs (TSCSCs) from breast CSCs and performed the transcription profile to reveal the mechanism. Mechanistically, we demonstrated that the behavior of therapeutic escape was regulated through the p38/MAPK signaling pathway, resulting in TSCSCs exhibiting enhanced motility and metastasis. Notably, blocking the p38/MAPK signaling pathway effectively reduced motility and metastasis ability both in vitro and in vivo, which were further supported by downregulated motility-related genes and epithelial-mesenchymal transition (EMT)-related proteins vimentin and N-cadherin. The obtained findings reveal the p38/MAPK pathway as a potential therapeutic target for TSCSCs and would provide profound implications for cancer therapy.

A region-confined PROTAC nanoplatform for spatiotemporally tunable protein degradation and enhanced cancer therapy

The antitumor performance of PROteolysis-TArgeting Chimeras (PROTACs) is limited by its insufficient tumor specificity and poor pharmacokinetics. These disadvantages are further compounded by tumor heterogeneity, especially the presence of cancer stem-like cells, which drive tumor growth and relapse. Herein, we design a region-confined PROTAC nanoplatform that integrates both reactive oxygen species (ROS)-activatable and hypoxia-responsive PROTAC prodrugs for the precise manipulation of bromodomain and extraterminal protein 4 expression and tumor eradication. These PROTAC nanoparticles selectively accumulate within and penetrate deep into tumors via response to matrix metalloproteinase-2. Photoactivity is then reactivated in response to the acidic intracellular milieu and the PROTAC is discharged due to the ROS generated via photodynamic therapy specifically within the normoxic microenvironment. Moreover, the latent hypoxia-responsive PROTAC prodrug is restored in hypoxic cancer stem-like cells overexpressing nitroreductase. Here, we show the ability of region-confined PROTAC nanoplatform to effectively degrade BRD4 in both normoxic and hypoxic environments, markedly hindering tumor progression in breast and head-neck tumor models.

Genetically engineered nanomodulators elicit potent immunity against cancer stem cells by checkpoint blockade and hypoxia relief

Rapid development of checkpoint inhibitors has provided significant breakthroughs for cancer stem cell (CSC) therapy, while the therapeutic efficacy is restricted by hypoxia-mediated tumor immune evasion, especially hypoxia-induced CD47 overexpression in CSCs. Herein, we developed a genetically engineered CSC membrane-coated hollow manganese dioxide (hMnO2@gCMs) to elicit robust antitumor immunity by blocking CD47 and alleviating hypoxia to ultimately achieve the eradication of CSCs. The hMnO2 core effectively alleviated tumor hypoxia by inducing decomposition of tumor endogenous H2O2, thus suppressing the CSCs and reducing the expression of CD47. Cooperating with hypoxia relief-induced downregulation of CD47, the overexpressed SIRPα on gCM shell efficiently blocked the CD47-SIRPα "don't eat me" pathway, synergistically eliciting robust antitumor-mediated immune responses. In a B16F10-CSC bearing melanoma mouse model, the hMnO2@gCMs showed an enhanced therapeutic effect in eradicating CSCs and inhibiting tumor growth. Our work presents a simple, safe, and robust platform for CSC eradication and cancer immunotherapy.

Oridonin, a small molecule inhibitor of cancer stem cell with potent cytotoxicity and differentiation potential

Cancer stem cells (CSCs) drive malignant tumor progression, recurrence, and metastasis with unique characteristics, including self-renewal and resistance to conventional treatments. Conventional differentiation inducers, although promising, have limited cytotoxicity and may inadvertently enhance CSC stemness. To address these challenges, ongoing efforts are dedicated to developing strategies that can effectively combine both cytotoxicity and differentiation-inducing effects. In this study, we introduce oridonin (Ori), a small molecule with dual differentiation-inducing and cytotoxicity properties capable of eliminating tumor CSCs. We isolated CSCs in B16F10 cells using the Hoechst side population method and assessed the differentiation effect of Ori. Ori's differentiation-inducing effect was further evaluated using human acute promyelocytic leukemia. The cytotoxic potential of Ori against MCF-7 and B16F10 cell lines was assessed through various methods. In vivo anti-tumor and anti-CSC efficacy of Ori was investigated using mouse melanoma and CSCs melanoma models. Safety evaluation included zebrafish embryotoxicity and mouse acute toxicity experiments. As a result, Ori effectively dismantles tumorspheres, inhibits proliferation, and reduces the expression of CSC-specific markers. It induces significant differentiation, especially in the case of NB4. Additionally, Ori upregulates TP53 expression, mitigates the hypoxic tumor microenvironment, suppresses stemness, and inhibits PD-L1 expression, prompting a robust anti-cancer immune response. Ori demonstrates pronounced cytotoxicity, inducing notable pro-apoptotic effects on B16F10 and MCF-7 cells, with specific triggering of mitochondrial apoptosis. Importantly, Ori maintains a commendable biosafety record. The dual-action prowess of Ori not only induces the differentiation of CSCs but also dispatches differentiated and residual tumor cells, effectively thwarting the relentless march of tumor progression.

Cancer stem cells: advances in knowledge and implications for cancer therapy

Cancer stem cells (CSCs), a small subset of cells in tumors that are characterized by self-renewal and continuous proliferation, lead to tumorigenesis, metastasis, and maintain tumor heterogeneity. Cancer continues to be a significant global disease burden. In the past, surgery, radiotherapy, and chemotherapy were the main cancer treatments. The technology of cancer treatments continues to develop and advance, and the emergence of targeted therapy, and immunotherapy provides more options for patients to a certain extent. However, the limitations of efficacy and treatment resistance are still inevitable. Our review begins with a brief introduction of the historical discoveries, original hypotheses, and pathways that regulate CSCs, such as WNT/β-Catenin, hedgehog, Notch, NF-κB, JAK/STAT, TGF-β, PI3K/AKT, PPAR pathway, and their crosstalk. We focus on the role of CSCs in various therapeutic outcomes and resistance, including how the treatments affect the content of CSCs and the alteration of related molecules, CSCs-mediated therapeutic resistance, and the clinical value of targeting CSCs in patients with refractory, progressed or advanced tumors. In summary, CSCs affect therapeutic efficacy, and the treatment method of targeting CSCs is still difficult to determine. Clarifying regulatory mechanisms and targeting biomarkers of CSCs is currently the mainstream idea.

A "Ferroptosis-Amplifier" Hydrogel for Eliminating Refractory Cancer Stem Cells Post-lumpectomy

The unique "Iron Addiction" feature of cancer stem cells (CSCs) with tumorigenicity and plasticity generally contributes to the tumor recurrence and metastasis after a lumpectomy. Herein, a novel "Ferroptosis Amplification" strategy is developed based on integrating gallic acid-modified FeOOH (GFP) and gallocyanine into Pluronic F-127 (F127) and carboxylated chitosan (CC)-based hydrogel for CSCs eradication. This "Ferroptosis Amplifier" hydrogel is thermally sensitive and achieves rapid gelation at the postsurgical wound in a breast tumor model. Specifically, gallocyanine, as the Dickkopf-1 (DKK1) inhibitor, can decrease the expression of SLC7A11 and GPX4 and synergistically induce ferroptosis of CSCs with GFP. Encouragingly, it is found that this combination suppresses the migratory and invasive capability of cancer cells via the downregulation of matrix metalloproteinase 7 (MMP7). The in vivo results further confirm that this "Ferroptosis Amplification" strategy is efficient in preventing tumor relapse and lung metastasis, manifesting an effective and promising postsurgical treatment for breast cancer.

Double-Layered Hollow Mesoporous Cuprous Oxide Nanoparticles for Double Drug Sequential Therapy of Tumors

Cancer stem cells (CSCs) are one of the determinants of tumor heterogeneity and are characterized by self-renewal, high tumorigenicity, invasiveness, and resistance to various therapies. To overcome the resistance of traditional tumor therapies resulting from CSCs, a strategy of double drug sequential therapy (DDST) for CSC-enriched tumors is proposed in this study and is realized utilizing the developed double-layered hollow mesoporous cuprous oxide nanoparticles (DL-HMCONs). The high drug-loading contents of camptothecin (CPT) and all-trans retinoic acid (ATRA) demonstrate that the DL-HMCON can be used as a generic drug delivery system. ATRA and CPT can be sequentially loaded in and released from CPT3@ATRA3@DL-HMCON@HA. The DDST mechanisms of CPT3@ATRA3@DL-HMCON@HA for CSC-containing tumors are demonstrated as follows: 1) the first release of ATRA from the outer layer induces differentiation from CSCs with high drug resistance to non-CSCs with low drug resistance; 2) the second release of CPT from the inner layer causes apoptosis of non-CSCs; and 3) the third release of Cu+ from DL-HMCON itself triggers the Fenton-like reaction and glutathione depletion, resulting in ferroptosis of non-CSCs. This CPT3@ATRA3@DL-HMCON@HA is verified to possess high DDST efficacy for CSC-enriched tumors with high biosafety.

Chitosan- and hyaluronic acid-based nanoarchitectures in phototherapy: Combination cancer chemotherapy, immunotherapy and gene therapy

Cancer phototherapy has been introduced as a new potential modality for tumor suppression. However, the efficacy of phototherapy has been limited due to a lack of targeted delivery of photosensitizers. Therefore, the application of biocompatible and multifunctional nanoparticles in phototherapy is appreciated. Chitosan (CS) as a cationic polymer and hyaluronic acid (HA) as a CD44-targeting agent are two widely utilized polymers in nanoparticle synthesis and functionalization. The current review focuses on the application of HA and CS nanostructures in cancer phototherapy. These nanocarriers can be used in phototherapy to induce hyperthermia and singlet oxygen generation for tumor ablation. CS and HA can be used for the synthesis of nanostructures, or they can functionalize other kinds of nanostructures used for phototherapy, such as gold nanorods. The HA and CS nanostructures can combine chemotherapy or immunotherapy with phototherapy to augment tumor suppression. Moreover, the CS nanostructures can be functionalized with HA for specific cancer phototherapy. The CS and HA nanostructures promote the cellular uptake of genes and photosensitizers to facilitate gene therapy and phototherapy. Such nanostructures specifically stimulate phototherapy at the tumor site, with particle toxic impacts on normal cells. Moreover, CS and HA nanostructures demonstrate high biocompatibility for further clinical applications.

Hierarchical self-recognition and response in CSC and non-CSC micro-niches for cancer therapy

Cancer stem cells (CSCs) characterized by self-renewal, invasiveness, tumorigenicity and resistance to treatment are regarded as the thorniest issues in refractory tumors. We develop a targeted and hierarchical controlled release nano-therapeutic platform (SEED-NPs) that self-identifies and responds to CSC and non-CSC micro-niches of tumors. In non-CSC micro-niche, reactive oxygen species (ROS) trigger the burst release of the chemotherapeutic drug and photosensitizer to kill tumor cells and reduce tumor volume by combining chemotherapy and photodynamic therapy (PDT). In CSC micro-niche, the preferentially released differentiation drug induces CSC differentiation and transforms CSCs into chemotherapy-sensitive cells. SEED-NPs exhibit an extraordinary capacity for downregulating the stemness of CD44+/CD24- SP (side population) cell population both in vitro and in vivo, and reveal a 4-fold increase of tumor-targeted accumulation. Also, PDT-generated ROS promote the formation of tunneling nanotubes and facilitate the divergent network transport of drugs in deep tumors. Moreover, ROS in turn promotes CSC differentiation and drug release. This positive-feedback-loop strategy enhances the elimination of refractory CSCs. As a result, SEED-NPs achieve excellent therapeutic effects in both 4T1 SP tumor-bearing mice and regular 4T1 tumor-bearing mice without obvious toxicities and eradicate half of mice tumors. SEED-NPs integrate differentiation, chemotherapy and PDT, which proved feasible and valuable, indicating that active targeting and hierarchical release are necessary to enhance antitumor efficacy. These findings provide promising prospects for overcoming barriers in the treatment of CSCs.

Sonodynamic and sonomechanical effect on cellular stemness and extracellular physicochemical environment to potentiate chemotherapy

BACKGROUND

Hypoxia-activated prodrug (HAP) is a promising candidate for highly tumor-specific chemotherapy. However, the oxygenation heterogeneity and dense extracellular matrix (ECM) of tumor, as well as the potential resistance to chemotherapy, have severely impeded the resulting overall efficacy of HAP.

RESULTS

A HAP potentiating strategy is proposed based on ultrasound responsive nanodroplets (PTP@PLGA), which is composed of protoporphyrin (PpIX), perfluoropropane (PFP) and a typical HAP, tirapazamine (TPZ). The intense vaporization of PFP upon ultrasound irradiation can magnify the sonomechanical effect, which loosens the ECM to promote the penetration of TPZ into the deep hypoxic region. Meanwhile, the PpIX enabled sonodynamic effect can further reduce the oxygen level, thus activating the TPZ in the relatively normoxic region as well. Surprisingly, abovementioned ultrasound effect also results in the downregulation of the stemness of cancer cells, which is highly associated with drug-refractoriness.

CONCLUSIONS

This work manifests an ideal example of ultrasound-based nanotechnology for potentiating HAP and also reveals the potential acoustic effect of intervening cancer stem-like cells.

Strategies for the Isolation and Identification of Gastric Cancer Stem Cells

Gastric cancer stem cells (GCSCs) originate from both gastric adult stem cells and bone marrow cells and are conspicuously present within the histological milieu of gastric cancer tissue. GCSCs play pivotal and multifaceted roles in the initiation, progression, and recurrence of gastric cancer. Hence, the characterization of GCSCs not only facilitates precise target identification for prospective therapeutic interventions in gastric cancer but also has significant implications for targeted therapy and the prognosis of gastric cancer. The prevailing techniques for GCSC purification involve their isolation using surface-specific cell markers, such as those identified by flow cytometry and immunomagnetic bead sorting techniques. In addition, in vitro culture and side-population cell sorting are integral methods in this context. This review discusses the surface biomarkers, isolation techniques, and identification methods of GCSCs, as well as their role in the treatment of gastric cancer.

Degradable bifunctional phototherapy composites based on upconversion nanoparticle-metal phenolic network for multimodal tumor therapy in the near-infrared biowindow

Phototherapy has garnered increasing attention as it allows for precise treatment of tumor sites with its accurate spatiotemporal control. In this study, we have successfully synthesized degradable bifunctional phototherapy agents (UCNPs@mSiO2@MPN-MC540/DOX) based on upconversion nanoparticle (UCNPs) and metal phenolic network (MPN), serving as a novel nanoplatform for multimodal tumor treatment in the near-infrared (NIR) biological window. To address the issue of low light penetration depth, the UCNPs we synthesized exhibited efficient light conversion ability under 808 nm laser irradiation to activate the photosensitizer Merocyanine 540 (MC540) for photodynamic therapy. Simultaneously, the 808 nm NIR light can also excite the MPN layer to achieve photothermal therapy for tumors. Additionally, the MPN layer possesses the capability of self-degradation under weakly acidic conditions. Within the tumor microenvironment, the MPN layer gradually degrades, facilitating the controlled release of the chemotherapy drug doxorubicin (DOX), thus achieving pH-responsive drug release and reducing the side effects of chemotherapy. This study provides an example of NIR-excited multimodal tumor treatment and pH-responsive drug release, offering a therapy model for precise tumor therapy.

Electrically activated polymetallic nanocrystals for long-term tumor suppression via oxygen-independent ROS generation and electro-immunotherapy

The low oxidation level and immunosuppressive microenvironment within hypoxic tumor tissue are critical factors contributing to the inefficacy of various anti-tumor strategies. Herein, we have designed a novel intravenous injection nanoplatform to conduct electro-immunotherapy, based on phospholipid-modified PtPd nanocrystals loaded with the immunoregulator IPI549 (LP@Pt-Pd@IPI549 nanoparticles, LPPI). LPPI responds to reactive oxygen species (ROS), triggering a cascade of therapeutic effects that overcome hypoxia-related resistance and effectively eradicate hypoxic tumors. Firstly, under electric field exposure, LPPI relied on water rather than oxygen to generate abundant ROS under hypoxic conditions for tumor electrodynamic therapy (EDT). Moreover, the generated ROS further induced the disintegration of the outer phospholipid membrane of LPPI, leading to the release of the immunoregulator and inhibition of myeloid-derived suppressor cells (MDSCs), triggering cascade immune responses. Additionally, the immunomodulatory effects of IPI549, in synergy with the immunogenic cell death (ICD) induced by EDT, reversed the immunosuppressive microenvironment contributing to tumor resistance. In summary, EDT transiently killed tumor cells while simultaneously generating antigen release, instigating an adaptive immune response for electro-immunotherapy, resulting in a potent and long-lasting tumor inhibition effect.

Single Molecular Nanomedicines Based on Macrocyclic Carrier-Drug Conjugates for Concentration-Independent Encapsulation and Precise Activation of Drugs

Nanomedicines often rely on noncovalent self-assembly and encapsulation for drug loading and delivery. However, challenges such as reproducibility issues due to the multicomponent nature, off-target activation caused by premature drug release, and complex pharmacokinetics arising from assembly dissociation have hindered their clinical translation. In this study, we introduce an innovative design concept termed single molecular nanomedicine (SMNM) based on macrocyclic carrier-drug conjugates. Through the covalent linkage of two chemotherapy drugs to a hypoxia-cleavable macrocyclic carrier, azocalix[4]arene, we obtained two self-included complexes to serve as SMNMs. The intramolecular inclusion feature of the SMNMs has not only demonstrated comprehensive shielding and protection for the drugs but also effectively prevented off-target drug leakage, thereby significantly reducing their side effects and enhancing their antitumor therapeutic efficacy. Additionally, the attributes of being a single component and molecularly dispersed confer advantages such as ease of preparation and good reproducibility for SMNMs, which is desirable for clinical applications.

Nanocarriers address intracellular barriers for efficient drug delivery, overcoming drug resistance, subcellular targeting and controlled release

The cellular barriers are major bottlenecks for bioactive compounds entering into cells to accomplish their biological functions, which limits their biomedical applications. Nanocarriers have demonstrated high potential and benefits for encapsulating bioactive compounds and efficiently delivering them into target cells by overcoming a cascade of intracellular barriers to achieve desirable therapeutic and diagnostic effects. In this review, we introduce the cellular barriers ahead of drug delivery and nanocarriers, as well as summarize recent advances and strategies of nanocarriers for increasing internalization with cells, promoting intracellular trafficking, overcoming drug resistance, targeting subcellular locations and controlled drug release. Lastly, the future perspectives of nanocarriers for intracellular drug delivery are discussed, which mainly focus on potential challenges and future directions. Our review presents an overview of intracellular drug delivery by nanocarriers, which may encourage the future development of nanocarriers for efficient and precision drug delivery into a wide range of cells and subcellular targets.

Glutathione Depletion-Induced Versatile Nanomedicine for Potentiating the Ferroptosis to Overcome Solid Tumor Radioresistance and Enhance Immunotherapy

A high level of reduced glutathione is a major factor contributing to the radioresistance observed in solid tumors. To address this radioresistance associated with glutathione, a cinnamaldehyde (CA) polymer prodrug, referred to as PDPCA, is fabricated. This prodrug is created by synthesizing a pendent CA prodrug with acetal linkages in a hydrophobic block, forming a self-assembled into a core-shell nanoparticle in aqueous media. Additionally, it encapsulates all-trans retinoic acid (ATRA) for synchronous delivery, resulting in PDPCA@ATRA. The PDPCA@ATRA nanoparticles accumulate reactive oxygen species through both endogenous and exogenous pathways, enhancing ferroptosis by depleting glutathione. This approach demonstrates efficacy in overcoming tumor radioresistance in vivo and in vitro, promoting the ferroptosis, and enhancing the cytotoxic T lymphocyte (CTL) response for lung tumors to anti-PD-1 (αPD-1) immunotherapy. Furthermore, this study reveals that PDPCA@ATRA nanoparticles promote ferroptosis through the NRF2-GPX4 signaling pathway, suggesting the potential for further investigation into the combination of radiotherapy and αPD-1 immune checkpoint inhibitors in cancer treatment.

In situ injectable hydrogel encapsulating Mn/NO-based immune nano-activator for prevention of postoperative tumor recurrence

Postoperative tumor recurrence remains a predominant cause of treatment failure. In this study, we developed an in situ injectable hydrogel, termed MPB-NO@DOX + ATRA gel, which was locally formed within the tumor resection cavity. The MPB-NO@DOX + ATRA gel was fabricated by mixing a thrombin solution, a fibrinogen solution containing all-trans retinoic acid (ATRA), and a Mn/NO-based immune nano-activator termed MPB-NO@DOX. ATRA promoted the differentiation of cancer stem cells, inhibited cancer cell migration, and affected the polarization of tumor-associated macrophages. The outer MnO2 shell disintegrated due to its reaction with glutathione and hydrogen peroxide in the cytoplasm to release Mn2+ and produce O2, resulting in the release of doxorubicin (DOX). The released DOX entered the nucleus and destroyed DNA, and the fragmented DNA cooperated with Mn2+ to activate the cGAS-STING pathway and stimulate an anti-tumor immune response. In addition, when MPB-NO@DOX was exposed to 808 nm laser irradiation, the Fe-NO bond was broken to release NO, which downregulated the expression of PD-L1 on the surface of tumor cells and reversed the immunosuppressive tumor microenvironment. In conclusion, the MPB-NO@DOX + ATRA gel exhibited excellent anti-tumor efficacy. The results of this study demonstrated the great potential of in situ injectable hydrogels in preventing postoperative tumor recurrence.

Lymph-targeted high-density lipoprotein-mimetic nanovaccine for multi-antigenic personalized cancer immunotherapy

Cancer vaccines show huge potential for cancer prevention and treatment. However, their efficacy remains limited due to weak immunogenicity regarding inefficient stimulation of cytotoxic T lymphocyte (CTL) responses. Inspired by the unique characteristic and biological function of high-density lipoprotein (HDL), we here develop an HDL-mimicking nanovaccine with the commendable lymph-targeted capacity to potently elicit antitumor immunity using lipid nanoparticle that is co-loaded with specific cancer cytomembrane harboring a collection of tumor-associated antigens and an immune adjuvant. The nanoparticulate impact is explored on the efficiency of lymphatic targeting and dendritic cell uptake. The optimized nanovaccine promotes the co-delivery of antigens and adjuvants to lymph nodes and maintains antigen presentation of dendritic cells, resulting in long-term immune surveillance as the elevated frequency of CTLs within lymphoid organs and tumor tissue. Immunization of nanovaccine suppresses tumor formation and growth and augments the therapeutic efficacy of checkpoint inhibitors notably on the high-stemness melanoma in the mouse models.

Unleashing the Potential of Camptothecin: Exploring Innovative Strategies for Structural Modification and Therapeutic Advancements

Camptothecin (CPT) is a potent anti-cancer agent targeting topoisomerase I (TOP1). However, CPT has poor pharmacokinetic properties, causes toxicities, and leads to drug resistance, which limit its clinical use. In this paper, to review the current state of CPT research. We first briefly explain CPT's TOP1 inhibition mechanism and the key hurdles in CPT drug development. Then we examine strategies to overcome CPT's limitations through structural modifications and advanced delivery systems. Though modifications alone seem insufficient to fully enhance CPT's therapeutic potential, structure-activity relationship analysis provides insights to guide optimization of CPT analogs. In comparison, advanced delivery systems integrating controlled release, imaging capabilities, and combination therapies via stimulus-responsive linkers and targeting moieties show great promise for improving CPT's pharmacological profile. Looking forward, multifaceted approaches combining selective CPT derivatives with advanced delivery systems, informed by emerging biological insights, hold promise for fully unleashing CPT's anti-cancer potential.