Ultrafast Low-Temperature Photothermal Therapy Activates Autophagy and Recovers Immunity for Efficient Antitumor Treatment

Research progress on new physical therapies for cancer (Review)

Currently, the clinical treatment of cancer is mainly based on surgery, chemotherapy and radiotherapy, but there are still problems associated with these treatments, such as disease recurrence and adverse reactions. The complexity and harmful nature of cancer mean that combining multiple treatment methods is an inevitable response. Therefore, it is of theoretical and practical significance to expand upon and study the aforementioned classic and traditional measures. With the advancement of technology, physical therapy has become important in the current research and treatment of cancer, and the physical factors related to cancer deserve in-depth study and discussion. The present review aimed to describe the mechanisms of action of pressure, temperature, photo-, sound and other physical therapies for cancer, which may provide new avenues for cancer treatment.

Tumor microenvironment modulation innovates combinative cancer therapy via a versatile graphene oxide nanosystem

The tumor microenvironment (TME) emerges as a unique challenge to oncotherapy due to its intricate ecosystem containing diverse cell types, extracellular matrix, secreted factors, and neovascularization, which furnish tumor growth, progression, invasion, and metastasis. Graphene oxide (GO)-based materials have garnered increasing attention in cancer therapy owing to their vast specific surface area, flexible lamellar structure, and electronic-photonic properties. Recently, interactions of GO with the TME have been broadly investigated, including trapping biomolecules, catalysis, cancer stem cell targeting, immunoreactions, etc., which inspires combinative therapeutic strategies to overcome TME obstacles. Herein, we summarize TME features, GO modulating various dimensions of the TME, and a TME-triggerable drug delivery system and highlight innovation and merits in combinative cancer therapy based on TME modulation. This review aims to offer researchers deeper insights into the interactions between versatile GO nanomaterials and the TME, facilitating the development of rational and reliable GO-based nanomedicines for advanced oncotherapy.

Utilizing gold nanoparticles in plasmonic photothermal therapy for cancer treatment

In recent decades, significant attention has been directed towards gold nanoparticles due to their exceptional properties, capturing the interest of researchers globally. Their unique characteristics, such as localized surface plasmon resonance, high surface area to volume ratio, biocompatibility, and facile surface functionalization, render them highly suitable for diverse applications, ranging from optoelectronics and sensing to surface-enhanced spectroscopies and biomedical uses, particularly in the realm of photothermal therapy. Plasmonic photothermal therapy, an emerging biomedical technology, has garnered substantial interest for its potential in cancer treatment and management. This approach employs photothermal agents, such as gold nanoparticles, which absorb light in the near-infrared region. When these agents accumulate within cancer cells, the absorbed photon energy is converted into heat, inducing local hyperthermia. This localized effect selectively eliminates damaged cells adjacent to nanoparticles while sparing normal cells. Various shapes and sizes of gold nanoparticles have proven well-suited candidates for photothermal therapy. This paper provides an overview of the distinctive properties of gold nanoparticles. It delves into the surface functionalization techniques crucial for ensuring cancer cells' effective retention and targeting of gold nanoparticles. In this context, the present paper reviews diverse applications of gold nanoparticles with different shapes in plasmonic photothermal therapy, encompassing nanospheres, nanorods, nanoshells, nanostars, and nanocages.

Traditional Chinese Medicine-Based Nanoformulations for Enhanced Photothermal Therapy of Cancer

Photothermal therapy (PTT) has shown promise in the ablation of small, unresectable tumors by boosting the tumor's temperature above 50 °C. However, the high local temperature-induced cancer cell necrosis could create severe local inflammation, which may deteriorate normal tissues and increase tumor spreading. Although mild photothermal therapy (MPTT) at 42-45 °C could avoid the undesired side effect to some extent with minimal nonspecific heat diffusion, the self-protective behavior of tumors during MPTT results in an unsatisfactory therapeutic effect. Inspired by the widespread applications of traditional Chinese medicine (TCM) in various ailments, we also extensively explored the use of TCM in PTT and MPTT. In this Review, we summarize the application and function of TCM in PTT and MPTT, including the following: (1) TCM improves the performance of PTT and MPTT by elevating the photothermal conversion ability of photothermal agents (PTAs) and overcoming the self-protective effect of tumors, (2) PTT enhances TCM-based chemotherapy by improving the sensitivity and cellular uptake of TCM in tumors, and (3) natural TCM and metal-chelated TCM-based nanoparticles could directly act as PTAs for carrier-free combination therapy. We expect this Review will further illuminate TCM's utility and applicability in cancer treatment and create new combination strategies for theragnostic use.

Effective Antitumor Synergistic Treatment with Fiber-Photothermal Therapy and Heat Shock Protein Inhibitors

Effective treatment of malignant tumors remains a thorny issue in current medicine. As a new type of anticancer strategy, photothermal therapy (PTT) has attracted tremendous attention due to its favorable therapeutic effectiveness, high spatial-temporal controllability, and low occurrence of side effects. However, the efficacy of PTT is significantly reduced due to the limited penetration of light and heat-induced overexpression of heat shock protein (Hsp). Herein, we propose an antitumor synergistic therapy that combines fiber-optic PTT and Hsp inhibitors. A rare-earth-doped optical fiber was used as the PTT actuator, and the Hsp inhibitor AT533 was loaded on the fiber surface by use of a hydrogel layer. PTT fibers can be guided to reach tumor lesions directly without being subject to the light penetration limit. The Hsp inhibitor can be released upon the softening of the hydrogel layer under photoheating to deactivate Hsp in the tumor and thus reduce the resistance of the tumor to PTT. This synergistic treatment enhanced the effect of PTT and successfully eradicated tumors in colorectal cancer (CRC) xenograft mouse models, providing a feasible way to realize antitumor and antirecurrence treatment. More importantly, the success of the synergistic treatment of PTT and Hsp inhibition opens new avenues for the development of multimodal and multitype synergistic fiber-optic treatments, which offer pronounced enhancement of therapeutic effectiveness for treating cancer.

A targeting nanoplatform for chemo-photothermal synergistic therapy of small-cell lung cancer

The precise delivery of drugs to tumor sites and the thermoresistance of tumors remain major challenges in photothermal therapy (PTT). Somatostatin receptor 2 (SSTR2) is proposed as an ideal target for the precise treatment of SCLC. We developed a targeting nano-drug delivery system comprising anti-SSTR2 monoclonal antibody (MAb) surface-modified nanoparticles co-encapsulating Cypate and gambogic acid (GA). The formed SGCPNs demonstrated excellent monodispersity, physiological stability, preferable biocompatibility, and resultant efficient photothermal conversion efficacy. SGCPNs were quickly internalized by SSTR2-overexpressing SCLC cells, triggering the release of GA under acidic and near-infrared (NIR) laser irradiation environments, leading to their escape from lysosomes to the cytosol and then diffusion into the nucleus. SGCPNs can not only decrease the cell survival rate but also inhibit the activity of heat shock protein 90 (HSP90). SGCPNs can be precisely delivered to xenograft tumors of SSTR2-positive SCLC in vivo. Upon NIR laser irradiation, therapy of SGCPNs showed significant tumor regression. In conclusion, SGCPNs provide a new chemo-photothermal synergistic treatment strategy for targeting SCLC.

2D nanomaterials-based delivery systems and their potentials in anticancer synergistic photo-immunotherapy

As the field of cancer therapeutics evolves, integrating two-dimensional (2D) nanomaterials with photo-immunotherapy has emerged as a promising approach with significant potential to augment cancer treatment efficacy. These 2D nanomaterials include graphene-based 2D nanomaterials, 2D MXenes, 2D layered double hydroxides, black phosphorus nanosheets, 2D metal-organic frameworks, and 2D transition metal dichalcogenides. They exhibit high load capacities, multiple functionalization pathways, optimal biocompatibility, and physiological stability. Predominantly, they function as anti-tumor delivery systems, amalgamating diverse therapeutic modalities, most notably phototherapy and immunotherapy, and the former is a recognized non-invasive treatment modality, and the latter represents the most promising anti-cancer strategy presently accessible. Thus, integrating phototherapy and immunotherapy founded on 2D nanomaterials unveils a novel paradigm in the war against cancer. This review delineates the latest developments in 2D nanomaterials as delivery systems for synergistic photo-immunotherapy in cancer treatment. We elaborate on the burgeoning realm of photo-immunotherapy, exploring the interplay between phototherapy and enhanced immune cells, immune response modulation, or immunosuppressive tumor microenvironments. Notably, the strategies to augment photo-immunotherapy have also been discussed. Finally, we discuss the challenges and future perspectives of these 2D nanomaterials in photo-immunotherapy.

A polylysine/hyaluronan-based core-shell nanoparticle triggers drug delivery by ATP/hyaluronidase dual stimuli for inducing apoptosis of breast cancer cells

The limitations of self-assembled polymeric nanoparticles for cancer therapy, including instability in the bloodstream, non-specific targeting of cancer cells, and unregulated intracellular drug delivery, were effectively addressed by the development of core-shell SNX@PLL-FPBA/mHA NPs. The core was SNX@PLL-FPBA NPs prepared from polylysine conjugated 3-fluoro-4-carboxyphenylboronic acid (PLL-FPBA) self-assembly and SNX encapsulation, while the shell was methacrylate-modified hyaluronic acid (mHA) adhering to the core by electrostatic interactions and subsequently stabilized by photo-crosslinking, without the use of any organic solvent. SNX@PLL-FPBA/mHA NPs exhibited good stability in varying ionic strengths (0-0.30 M NaCl), pH levels (6.8 and 7.4), and plasma environments mimicking the blood, ensuring their efficacy in systemic circulation. The drug delivery from the nanoparticles was highly sensitive to ATP/Hyals stimuli (82 % within 48 h), closely mimicking the intracellular environment of breast cancer cells. The nanoparticles demonstrated good hemocompatibility and non-toxicity towards human skin fibroblasts. Efficient internalization of SNX@PLL-FPBA/mHA NPs by MCF-7 and MDA-MB-231 breast cancer cells was observed by CLSM and flow cytometry. The intracellular ATP/Hyals stimuli triggered the rapid drug delivery and induced cellular apoptosis. Thus, SNX@PLL-FPBA/mHA NPs were a promising drug nanocarrier for breast cancer therapy, offering improved stability, targeted delivery, and controlled drug release to enhance treatment outcomes.

High-Performance NIR-II Fluorescent Type I/II Photosensitizer Enabling Augmented Mild Photothermal Therapy of Tumors by Disrupting Heat Shock Proteins

NIR-II fluorescent photosensitizers as phototheranostic agents hold considerable promise in the application of mild photothermal therapy (MPTT) for tumors, as the reactive oxygen species generated during photodynamic therapy can effectively disrupt heat shock proteins. Nevertheless, the exclusive utilization of these photosensitizers to significantly augment the MPTT efficacy has rarely been substantiated, primarily due to their insufficient photodynamic performance. Herein, the utilization of high-performance NIR-II fluorescent type I/II photosensitizer (AS21:4) is presented as a simple but effective nanoplatform derived from molecule AS2 to enhance the MPTT efficacy of tumors without any additional therapeutic components. By taking advantage of heavy atom effect, AS21:4 as a type I/II photosensitizer demonstrates superior efficacy in producing 1O2 (1O2 quantum yield = 12.4%) and O2 •- among currently available NIR-II fluorescent photosensitizers with absorption exceeding 800 nm. In vitro and in vivo findings demonstrate that the 1O2 and O2 •- generated from AS21:4 induce a substantial reduction in the expression of HSP90, thereby improving the MPTT efficacy. The remarkable phototheranostic performance, substantial tumor accumulation, and prolonged tumor retention of AS21:4, establish it as a simple but superior phototheranostic agent for NIR-II fluorescence imaging-guided MPTT of tumors.

All Roads Lead to Rome: Comparing Nanoparticle- and Small Molecule-Driven Cell Autophagy

Autophagy, vital for removing cellular waste, is triggered differently by small molecules and nanoparticles. Small molecules, like rapamycin, non-selectively activate autophagy by inhibiting the mTOR pathway, which is essential for cell regulation. This can clear damaged components but may cause cytotoxicity with prolonged use. Nanoparticles, however, induce autophagy, often causing oxidative stress, through broader cellular interactions and can lead to a targeted form known as "xenophagy." Their impact varies with their properties but can be harnessed therapeutically. In this review, the autophagy induced by nanoparticles is explored and small molecules across four dimensions: the mechanisms behind autophagy induction, the outcomes of such induction, the toxicological effects on cellular autophagy, and the therapeutic potential of employing autophagy triggered by nanoparticles or small molecules. Although small molecules and nanoparticles each induce autophagy through different pathways and lead to diverse effects, both represent invaluable tools in cell biology, nanomedicine, and drug discovery, offering unique insights and therapeutic opportunities.

Autophagy-Inducing MoO3-x Nanowires Boost Photothermal-Triggered Cancer Immunotherapy

Autophagy could play suppressing role in cancer therapy by facilitating release of tumor antigens from dying cells and inducing immunogenic cell death (ICD). Therefore, discovery and rational design of more effective inducers of cytotoxic autophagy is expected to develop new strategies for finding innovative drugs for precise and successful cancer treatment. Herein, we develop MoO3-x nanowires (MoO3-x NWs) with high oxygen vacancy and strong photothermal responsivity to ablate tumors through hyperthermia, thus promote the induction of cytotoxic autophagy and severe ICD. As expected, the combination of MoO3-x NWs and photothermal therapy (PTT) effectively induces autophagy to promote the release of tumor antigens from the ablated cells, and induces the maturation and antigen presentation of dendritic cells (DCs), subsequently activates cytotoxic T lymphocytes (CTLs)-mediated adaptive immunity. Furthermore, the combination treatment of MoO3-x NWs with immune checkpoint blockade of PD-1 could promote the tumor-associated macrophages (TAMs) polarization into tumor-killing M1 macrophages, inhibit infiltration of Treg cells at tumor sites, and alleviate immunosuppression in the tumor microenvironment, finally intensify the anti-tumor activity in vivo. This study provides a strategy and preliminary elucidation of the mechanism of using MoO3-x nanowires with high oxygen vacancy to induce autophagy and thus enhance photothermal immunotherapy.

Pan-cancer analysis of T-cell proliferation regulatory genes as potential immunotherapeutic targets

T cells are the key to killing tumor cells. However, the exact mechanism of their role in cancer is not fully understood. Therefore, a comprehensive understanding of the role of T-cell proliferation regulatory genes in tumors is needed. In our study, we investigated the expression levels of genes controlling T-cell proliferation, their impact on prognosis, and their genetic variations. Additionally, we explored their associations with TMB, MSI, ESTIMATEScore, ImmuneScore, StromalScore, and immune cell infiltration. We examined the role of these genes in cancer-related pathways using GSEA. Furthermore, we calculated their activity levels across various types of cancer. Drug analysis was also conducted targeting these genes. Single-cell analysis, LASSO Cox model construction, and prognosis analysis were performed. We observed distinct expression patterns of T-cell proliferation regulatory genes across different malignant tumors. Their abnormal expression may be caused by CNA and DNA methylation. In certain cancers, they also showed complex associations with TMB and MSI. Moreover, in many tumors, they exhibited significant positive correlations with ESTIMATEScores, ImmuneScore, and StromalScore. Additionally, in most tumors, their GSVA scores were significantly positively correlated with various T-cell subtypes. GSEA analysis revealed their involvement in multiple immune pathways. Furthermore, we found that model scores were associated with patient prognosis and related to tumor malignancy progression. T-cell proliferation regulatory genes are closely associated with the tumor immune microenvironment (TIM), especially T cells. Targeting them may be an essential approach for cancer immunotherapy.

Nanotherapeutics targeting autophagy regulation for improved cancer therapy

The clinical efficacy of current cancer therapies falls short, and there is a pressing demand to integrate new targets with conventional therapies. Autophagy, a highly conserved self-degradation process, has received considerable attention as an emerging therapeutic target for cancer. With the rapid development of nanomedicine, nanomaterials have been widely utilized in cancer therapy due to their unrivaled delivery performance. Hence, considering the potential benefits of integrating autophagy and nanotechnology in cancer therapy, we outline the latest advances in autophagy-based nanotherapeutics. Based on a brief background related to autophagy and nanotherapeutics and their impact on tumor progression, the feasibility of autophagy-based nanotherapeutics for cancer treatment is demonstrated. Further, emerging nanotherapeutics developed to modulate autophagy are reviewed from the perspective of cell signaling pathways, including modulation of the mammalian target of rapamycin (mTOR) pathway, autophagy-related (ATG) and its complex expression, reactive oxygen species (ROS) and mitophagy, interference with autophagosome-lysosome fusion, and inhibition of hypoxia-mediated autophagy. In addition, combination therapies in which nano-autophagy modulation is combined with chemotherapy, phototherapy, and immunotherapy are also described. Finally, the prospects and challenges of autophagy-based nanotherapeutics for efficient cancer treatment are envisioned.

Self-Delivery Nanomedicines Reverse Thermal Resistance to Enhance Tumor Mild-Temperature Photothermal Therapy

Tumoral thermal defense mechanisms considerably attenuate the therapeutic outcomes of mild-temperature photothermal therapy (PTT). Thus, developing a simple, efficient, and universal therapeutic strategy to sensitize mild-temperature PTT is desirable. Herein, we report self-delivery nanomedicines ACy NPs comprising a near-infrared (NIR) photothermal agent (Cypate), mitochondrial oxidative phosphorylation inhibitor (ATO), and distearoylphosphatidylethanolamine-polyethylene glycol 2000 (DSPE-PEG2000), which have a high drug-loading efficiency that can reverse tumoral thermal resistance, thereby increasing mild-temperature PTT efficacy. ACy NPs achieved targeted tumor accumulation and performed NIR fluorescence imaging capability in vivo to guide tumor PTT for optimized therapeutic outcomes. The released ATO reduced intracellular ATP levels to downregulate multiple heat shock proteins (including HSP70 and HSP90) before PTT, which reversed the thermal resistance of tumor cells, contributing to the excellent results of mild-temperature PTT in vitro and in vivo. Therefore, this study provides a simple, biosafe, advanced, and universal heat shock protein-blocking strategy for tumor PTT.

The Emerging Landscape for Combating Resistance Associated with Energy-Based Therapies via Nanomedicine

Cancer represents a serious disease with significant implications for public health, imposing substantial economic burden and negative societal consequences. Compared to conventional cancer treatments, such as surgery and chemotherapy, energy-based therapies (ET) based on athermal and thermal ablation provide distinct advantages, including minimally invasive procedures and rapid postoperative recovery. Nevertheless, due to the complex pathophysiology of many solid tumors, the therapeutic effectiveness of ET is often limited. Nanotechnology offers unique opportunities by enabling facile material designs, tunable physicochemical properties, and excellent biocompatibility, thereby further augmenting the outcomes of ET. Numerous nanomaterials have demonstrated the ability to overcome intrinsic therapeutic resistance associated with ET, leading to improved antitumor responses. This comprehensive review systematically summarizes the underlying mechanisms of ET-associated resistance (ETR) and highlights representative applications of nanoplatforms used to mitigate ETR. Overall, this review emphasizes the recent advances in the field and presents a detailed account of novel nanomaterial designs in combating ETR, along with efforts aimed at facilitating their clinical translation.

POSS Engineering of Multifunctional Nanoplatforms for Chemo-Mild Photothermal Synergistic Therapy

Chemo-mild photothermal synergistic therapy can effectively inhibit tumor growth under mild hyperthermia, minimizing damage to nearby healthy tissues and skin while ensuring therapeutic efficacy. In this paper, we develop a multifunctional study based on polyhedral oligomeric sesquisiloxane (POSS) that exhibits a synergistic therapeutic effect through mild photothermal and chemotherapy treatments (POSS-SQ-DOX). The nanoplatform utilizes SQ-N as a photothermal agent (PTA) for mild photothermal, while doxorubicin (DOX) serves as the chemotherapeutic drug for chemotherapy. By incorporating POSS into the nanoplatform, we successfully prevent the aggregation of SQ-N in aqueous solutions, thus maintaining its excellent photothermal properties both in vitro and in vivo. Furthermore, the introduction of polyethylene glycol (PEG) significantly enhances cell permeability, which contributes to the remarkable therapeutic effect of POSS-SQ-DOX NPs. Our studies on the photothermal properties of POSS-SQ-DOX NPs demonstrate their high photothermal conversion efficiency (62.3%) and stability, confirming their suitability for use in mild photothermal therapy. A combination index value (CI = 0.72) verified the presence of a synergistic effect between these two treatments, indicating that POSS-SQ-DOX NPs exhibited significantly higher cell mortality (74.7%) and tumor inhibition rate (72.7%) compared to single chemotherapy and mild photothermal therapy. This observation highlights the synergistic therapeutic potential of POSS-SQ-DOX NPs. Furthermore, in vitro and in vivo toxicity tests suggest that the absence of cytotoxicity and excellent biocompatibility of POSS-SQ-DOX NPs provide a guarantee for clinical applications. Therefore, utilizing near-infrared light-triggering POSS-SQ-DOX NPs can serve as chemo-mild photothermal PTA, while functionalized POSS-SQ-DOX NPs hold great promise as a novel nanoplatform that may drive significant advancements in the field of chemo-mild photothermal therapy.

A pro-death autophagy-based nanoplatform for enhancing antitumour efficacy with improved immune responses

Due to the pro-survival effect of mild autophagy, the therapeutic effect of chemo-immunotherapy is unsatisfactory. In addition, the adverse tumour microenvironment (TME), including the lack of antigen presentation, the deficiency of oxygen supply and immunosuppressive cells, results in immune escape and metastasis. Herein, a novel nanoplatform (CS-3BP/PA@DOX) based on the autophagy cascade is proposed for the first time to deliver the chemotherapeutic doxorubicin (DOX) and respiration inhibitor 3-bromopyruvic acid (3BP) to overcome the above obstacles. CS-3BP/PA@DOX exerts a synergistic therapeutic effect to initiate pro-death autophagy and facilitate the antigen presentation process by combining DOX chemotherapy and starvation therapy with 3BP. Additionally, CS-3BP/PA@DOX remodelled the immunosuppressive TME by alleviating hypoxia, damaging dense ECM, and downregulating PD-L1 to enhance antitumour immunity. 3BP was found to promote GSH depletion by inhibiting respiration for the first time, which reduces the chemical resistance of cancer and increases the sensitivity of cells to ROS, providing a new therapeutic direction of 3BP for antitumour treatment. Collectively, this study offers an opportunity to magnify pro-death autophagy, augment antitumour efficacy, facilitate anti-metastatic effects, and boost immune responses.

Mitochondria-targeting Cu3VS4 nanostructure with high copper ionic mobility for photothermoelectric therapy

Thermoelectric therapy has emerged as a promising treatment strategy for oncology, but it is still limited by the low thermoelectric catalytic efficiency at human body temperature and the inevitable tumor thermotolerance. We present a photothermoelectric therapy (PTET) strategy based on triphenylphosphine-functionalized Cu3VS4 nanoparticles (CVS NPs) with high copper ionic mobility at room temperature. Under near-infrared laser irradiation, CVS NPs not only generate hyperthermia to ablate tumor cells but also catalytically yield superoxide radicals and induce endogenous NADH oxidation through the Seebeck effect. Notably, CVS NPs can accumulate inside mitochondria and deplete NADH, reducing ATP synthesis by competitively inhibiting the function of complex I, thereby down-regulating the expression of heat shock proteins to relieve tumor thermotolerance. Both in vitro and in vivo results show notable tumor suppression efficacy, indicating that the concept of integrating PTET and mitochondrial metabolism modulation is highly feasible and offers a translational promise for realizing precise and efficient cancer treatment.

A plasmonic fluorescent ratiometric temperature sensor for self-limiting hyperthermic applications utilizing FRET enhancement in the plasmonic field

Nanoparticle mediated photo-induced hyperthermia holds much promise as a therapeutic solution for the management of diseases like cancer. The conventional methods of temperature measurements do not measure the actual temperature generated in the vicinity of the nanoparticles during illumination. In contrast, nano temperature sensors built on hyperthermic nanoparticles can relay local temperatures around the nanoparticles during thermal induction. In this study, we present a core shell construct consisting of a plasmonic core and a silica shell encapsulating a FRET pair of organic dyes for such application. The plasmonic core imparts photo-induced hyperthermic properties to the nanoconstruct, while the fluorescent shell enables ratiometric sensing of temperature. We see that even at a low dye encapsulation concentration, the shell displays a linear ratiometric fluorescence response to temperature and high energy transfer between the dye pair. Interestingly, Monte Carlo simulations, without considering the plasmonic core, show that the energy transfer in the system should be much smaller than that observed, confirming plasmon enhancement in the FRET energy transfer. We also show the ratiometric temperature measurement using these particles during photoinduced hyperthermia. This study suggests the use of plasmonic nanoparticles in the next generation "self-limiting" photothermal therapy.

Folate targeting self-limiting hyperthermic nanoparticles for controlled photothermal therapy

Photothermal therapy utilizes photothermal agents and the use of nanoparticle agents is deemed advantageous for multiple reasons. Common nano-photothermal agents normally have high conversion efficiencies and heating rates, but bulk temperature measurement methods do not adequately represent the nanoscale temperatures of these nanoheaters. Herein, we report on the fabrication of self-limiting hyperthermic nanoparticles that can simultaneously photoinduce hyperthermia and report back temperature ratiometrically. The synthesized nanoparticles utilize a plasmonic core to achieve the photoinduced hyperthermic property and fluorescent FRET pairs entrapped in a silica shell to impart the ratiometric temperature sensing ability. The studies demonstrate the photoinduced hyperthermia with simultaneous temperature measurement using these particles and show that the particles can achieve a conversion efficiency of 19.5% despite the shell architecture. These folate-functionalized self-limiting photothermal agents are also used to demonstrate targeted photoinduced hyperthermia in a HeLa cell model.

Multifunctional gold nanorods in low-temperature photothermal interactions for combined tumor starvation and RNA interference therapy

Collateral damage to healthy tissue, uneven heat distribution, inflammatory diseases, and tumor metastasis induction hinder the translation of high-temperature photothermal therapy (PTT) from bench to practical clinical applications. In this report, a multifunctional gold nanorod (GNR)-based nanosystem was designed by attaching siRNA against B7-H3 (B7-H3si), glucose oxidase (GOx), and hyaluronic acid (HA) for efficient low-temperature PTT. Herein, GOx can not only exhaust glucose to induce starvation therapy but also reduce the heat shock protein (HSP), realizing the ablation of tumors without damage to healthy tissues. Evidence shows that B7-H3, a type I transmembrane glycoprotein molecule, plays essential roles in growth, metastasis, and drug resistance. By initiating the downregulation of B7-H3 by siRNA, siRNA-GOx/GNR@HA NPs may promote the effectiveness of treatment. By targeting cluster of differentiation 44 (CD44) and depleting B7-H3 and HSPs sequentially, siRNA-GOx/GNR@HA NPs showed 12.9-fold higher lung distribution than siRNA-GOx/GNR NPs. Furthermore, 50% of A549-bearing mice in the siRNA-GOx/GNR NPs group survived over 50 days. Overall, this low-temperature phototherapeutic nanosystem provides an appropriate strategy for eliminating cancer with high treatment effectiveness and minimal systemic toxicity. STATEMENT OF SIGNIFICANCE: To realize efficient tumor ablation under mild low-temperature (42-45 ℃) and RNA interference simultaneously, here we developed a multifunctional gold nanorod (GNR)-based nanosystem (siRNA-GOx/GNR@HA NPs). This nanoplatform can significantly inhibit tumor cell proliferation and induce cell apoptosis by downregulation of HSP90α, HSP70, B7-H3, p-AKT, and p-ERK and upregulation of cleaved caspase-9 at mild low-temperature due to its superior tumor homing ability and the combined effect of photothermal effect, glucose deprivation-initiated tumor starvation, and B7-H3 gene silence effect. It is believed that this multifunctional low-temperature photothermal nanosystem with efficient and specific anticancer properties, shows a potential application in clinical tumor treatment.

Molecular Engineering of pH-Responsive NIR Oxazine Assemblies for Evoking Tumor Ferroptosis via Triggering Lysosomal Dysfunction

Ferroptosis, a newly discovered form of regulated cell death, is emerging as a promising approach to tumor therapy. However, the spatiotemporal control of cell-intrinsic Fenton chemistry to modulate tumor ferroptosis remains challenging. Here, we report an oxazine-based activatable molecular assembly (PTO-Biotin Nps), which is capable of triggering the lysosomal dysfunction-mediated Fenton pathway with excellent spatiotemporal resolution via near-infrared (NIR) light to evoke ferroptosis. In this system, a pH-responsive NIR photothermal oxazine molecule was designed and functionalized with a tumor-targeting hydrophilic biotin-poly(ethylene glycol) (PEG) chain to engineer well-defined nanostructured assemblies within a single-molecular framework. PTO-Biotin Nps possesses a selective tropism to lysosome accumulation inside tumor cells, accommodated by its enhanced photothermal activity in the acidic microenvironment. Upon NIR light activation, PTO-Biotin Nps promoted lysosomal dysfunction and induced cytosolic acidification and impaired autophagy. More importantly, photoactivation-mediated lysosomal dysfunction via PTO-Biotin Nps was found to markedly enhance cellular Fenton reactions and evoke ferroptosis, thereby improving antitumor efficacy and mitigating systemic side effects. Overall, our study demonstrates that the molecular engineering approach of pH-responsive photothermal oxazine assemblies enables the spatiotemporal modulation of the intrinsic ferroptosis mechanism, offering a novel strategy for the development of metal-free Fenton inducers in antitumor therapy.

Oxidative stress induced by berberine-based mitochondria-targeted low temperature photothermal therapy

Introduction: Mitochondria-targeted low-temperature photothermal therapy (LPTT) is a promising strategy that could maximize anticancer effects and overcome tumor thermal resistance. However, the successful synthesis of mitochondria-targeted nanodrug delivery system for LPTT still faces diverse challenges, such as laborious preparations processes, low drug-loading, and significant systemic toxicity from the carriers. Methods: In this study, we used the tumor-targeting folic acid (FA) and mitochondria-targeting berberine (BBR) derivatives (BD) co-modified polyethylene glycol (PEG)-decorated graphene oxide (GO) to synthesize a novel mitochondria-targeting nanocomposite (GO-PEG-FA/BD), which can effectively accumulate in mitochondria of the osteosarcoma (OS) cells and achieve enhanced mitochondria-targeted LPTT effects with minimal cell toxicity. The mitochondria-targeted LPTT effects were validated both in vitro and vivo. Results: In vitro experiments, the nanocomposites (GO-PEG-FA/BD) could eliminate membrane potential (ΔΨm), deprive the ATP of cancer cells, and increase the levels of reactive oxygen species (ROS), which ultimately induce oxidative stress damage. Furthermore, in vivo results showed that the enhanced mitochondria-targeted LPTT could exert an excellent anti-cancer effect with minimal toxicity. Discussion: Taken together, this study provides a practicable strategy to develop an ingenious nanoplatform for cancer synergetic therapy via mitochondria-targeted LPTT, which hold enormous potential for future clinical translation.

Inhibition of autophagy and MEK promotes ferroptosis in Lkb1-deficient Kras-driven lung tumors

LKB1 and KRAS are the third most frequent co-mutations detected in non-small cell lung cancer (NSCLC) and cause aggressive tumor growth. Unfortunately, treatment with RAS-RAF-MEK-ERK pathway inhibitors has minimal therapeutic efficacy in LKB1-mutant KRAS-driven NSCLC. Autophagy, an intracellular nutrient scavenging pathway, compensates for Lkb1 loss to support Kras-driven lung tumor growth. Here we preclinically evaluate the possibility of autophagy inhibition together with MEK inhibition as a treatment for Kras-driven lung tumors. We found that the combination of the autophagy inhibitor hydroxychloroquine (HCQ) and the MEK inhibitor Trametinib displays synergistic anti-proliferative activity in KrasG12D/+;Lkb1-/- (KL) lung cancer cells, but not in KrasG12D/+;p53-/- (KP) lung cancer cells. In vivo studies using tumor allografts, genetically engineered mouse models (GEMMs) and patient-derived xenografts (PDXs) showed anti-tumor activity of the combination of HCQ and Trametinib on KL but not KP tumors. We further found that the combination treatment significantly reduced mitochondrial membrane potential, basal respiration, and ATP production, while also increasing lipid peroxidation, indicative of ferroptosis, in KL tumor-derived cell lines (TDCLs) and KL tumors compared to treatment with single agents. Moreover, the reduced tumor growth by the combination treatment was rescued by ferroptosis inhibitor. Taken together, we demonstrate that autophagy upregulation in KL tumors causes resistance to Trametinib by inhibiting ferroptosis. Therefore, a combination of autophagy and MEK inhibition could be a novel therapeutic strategy to specifically treat NSCLC bearing co-mutations of LKB1 and KRAS.

Research Progress of Nanomedicine-Based Mild Photothermal Therapy in Tumor

With the booming development of nanomedicine, mild photothermal therapy (mPTT, 42-45°C) has exhibited promising potential in tumor therapy. Compared with traditional PTT (>50°C), mPTT has less side effects and better biological effects conducive to tumor treatment, such as loosening the dense structure in tumor tissues, enhancing blood perfusion, and improving the immunosuppressive microenvironment. However, such a relatively low temperature cannot allow mPTT to completely eradicate tumors, and therefore, substantial efforts have been conducted to optimize the application of mPTT in tumor therapy. This review extensively summarizes the latest advances of mPTT, including two sections: (1) taking mPTT as a leading role to maximize its effect by blocking the cell defense mechanisms, and (2) regarding mPTT as a supporting role to assist other therapies to achieve synergistic antitumor curative effect. Meanwhile, the special characteristics and imaging capabilities of nanoplatforms applied in various therapies are discussed. At last, this paper puts forward the bottlenecks and challenges in the current research path of mPTT, and possible solutions and research directions in future are proposed correspondingly.

Enhancing the Efficiency of Mild-Temperature Photothermal Therapy for Cancer Assisting with Various Strategies

Conventional photothermal therapy (PTT) irradiates the tumor tissues by elevating the temperature above 48 °C to exert thermal ablation, killing tumor cells. However, thermal ablation during PTT harmfully damages the surrounding normal tissues, post-treatment inflammatory responses, rapid metastasis due to the short-term mass release of tumor-cellular contents, or other side effects. To circumvent this limitation, mild-temperature photothermal therapy (MTPTT) was introduced to replace PTT as it exerts its activity at a therapeutic temperature of 42-45 °C. However, the significantly low therapeutic effect comes due to the thermoresistance of cancer cells as MTPTT figures out some of the side-effects issues. Herein, our current review suggested the mechanism and various strategies for improving the efficacy of MTPTT. Especially, heat shock proteins (HSPs) are molecular chaperones overexpressed in tumor cells and implicated in several cellular heat shock responses. Therefore, we introduced some methods to inhibit activity, reduce expression levels, and hinder the function of HSPs during MTPTT treatment. Moreover, other strategies also were emphasized, including nucleus damage, energy inhibition, and autophagy mediation. In addition, some therapies, like radiotherapy, chemotherapy, photodynamic therapy, and immunotherapy, exhibited a significant synergistic effect to assist MTPTT. Our current review provides a basis for further studies and a new approach for the clinical application of MTPTT.

Nanomaterial-mediated low-temperature photothermal therapy via heat shock protein inhibition

With the continuous development of nanobiotechnology in recent years, combining photothermal materials with nanotechnology for tumor photothermal therapy (PTT) has drawn many attentions nanomedicine research. Although nanomaterial-mediated PTT is more specific and targeted than traditional treatment modalities, hyperthermia can also damage normal cells. Therefore, researchers have proposed the concept of low-temperature PTT, in which the expression of heat shock proteins (HSPs) is inhibited. In this article, the research strategies proposed in recent years based on the inhibition of HSPs expression to achieve low-temperature PTT was reviewed. Folowing this, the synthesis, properties, and applications of these nanomaterials were introduced. In addition, we also summarized the problems of nanomaterial-mediated low-temperature PTT at this stage and provided an outlook on future research directions.

Precisely NIR-II-activated and pH-responsive cascade catalytic nanoreactor for controlled drug release and self-enhanced synergetic therapy

Mesoporous polydopamine (MPDA) and MPDA-based nanosystems have been widely used in the field of photothermal therapy (PTT) and drug delivery. However, synthesis of the corresponding nanoplatforms for efficient PTT and controlled drug release simultaneously in the second near infrared (NIR-II) region remains a great challenge. Herein, a NIR-II and pH dual-responsive HMPDA@Cu_2-xSe cascade catalytic nanoplatform was constructed by assembling hollow mesoporous polydopamine (HMPDA) with ultra-small Cu_2-xSe, which could compensate the inadequate NIR-II-induced PTT effect of HMPDA and enhance the efficacy of chemodynamic therapy (CDT) simultaneously under NIR-II laser irradiation. Meanwhile, doxorubicin (DOX) and glucose oxidase (GOx) were encapsulated into the synthesized HMPDA@Cu_2-xSe using the photothermal-induced phase change material (PCM) tetradecyl (1-TD) as a gatekeeper to achieve the controlled release of the cargo. Under 1064 nm laser, the generated heat could cause 1-TD melting, resulting in the release of large amounts of DOX and GOx. The released GOx could further catalyze glucose to H₂O₂ and gluconic acid, which in turn promoted the effects of PTT/CDT and the release of drugs. In vitro and in vivo experiments showed that the synthesized HMPDA@Cu_2-xSe-DOX-GOx@PCM (HMPC-D/G@PCM) nanosystem exhibited a significant tumor cell inhibition effect by combining different treatment modes. Thus, this smart nanoplatform with multiple stimuli-activated cascade reactions provided a new idea for designing effective multi-modal combination therapy for tumors.

Eutectic Gallium-Indium Nanoparticles for Photodynamic Therapy of Pancreatic Cancer

Developing a cancer theranostic nanoplatform with diagnosis and treatment capabilities to effectively treat tumors and reduce side effects is of great significance. Herein, we present a drug delivery strategy for photosensitizers based on a new liquid metal nanoplatform that leverages the tumor microenvironment to achieve photodynamic therapeutic effects in pancreatic cancer. Eutectic gallium indium (EGaIn) nanoparticles were successfully conjugated with a water-soluble cancer targeting ligand, hyaluronic acid, and a photosensitizer, benzoporphyrin derivative, creating EGaIn nanoparticles (EGaPs) via a simple green sonication method. The prepared sphere-shaped EGaPs, with a core-shell structure, presented high biocompatibility and stability. EGaPs had greater cellular uptake, manifested targeting competence, and generated significantly higher intracellular ROS. Further, near-infrared light activation of EGaPs demonstrated their potential to effectively eliminate cancer cells due to their single oxygen generation capability. Finally, from in vivo studies, EGaPs caused tumor regression and resulted in 2.3-fold higher necrosis than the control, therefore making a good vehicle for photodynamic therapy. The overall results highlight that EGaPs provide a new way to assemble liquid metal nanomaterials with different ligands for enhanced cancer therapy.

Nanoparticle-Mediated Photothermal Therapy Limitation in Clinical Applications Regarding Pain Management

The development of new effective cancer treatment methods has attracted much attention, mainly due to the limited efficacy and considerable side effects of currently used cancer treatment methods such as radiation therapy and chemotherapy. Photothermal therapy based on the use of plasmonically resonant metallic nanoparticles has emerged as a promising technique to eradicate cancer cells selectively. In this method, plasmonic nanoparticles are first preferentially uptaken by a tumor and then selectively heated by exposure to laser radiation with a specific plasmonic resonant wavelength, to destroy the tumor whilst minimizing damage to adjacent normal tissue. However, several parameters can limit the effectiveness of photothermal therapy, resulting in insufficient heating and potentially leading to cancer recurrence. One of these parameters is the patient's pain sensation during the treatment, if this is performed without use of anesthetic. Pain can restrict the level of applicable laser radiation, cause an interruption to the treatment course and, as such, affect its efficacy, as well as leading to a negative patient experience and consequential general population hesitancy to this type of therapy. Since having a comfortable and painless procedure is one of the important treatment goals in the clinic, along with its high effectiveness, and due to the relatively low number of studies devoted to this specific topic, we have compiled this review. Moreover, non-invasive and painless methods for temperature measurement during photothermal therapy (PTT), such as Raman spectroscopy and nanothermometry, will be discussed in the following. Here, we firstly outline the physical phenomena underlying the photothermal therapy, and then discuss studies devoted to photothermal cancer treatment concerning pain management and pathways for improved efficiency of photothermal therapy whilst minimizing pain experienced by the patient.

Nanomaterials for photothermal and photodynamic cancer therapy

In recent years, the role of optically sensitive nanomaterials has become powerful moieties in therapeutic techniques and has become particularly emphasized. Currently, by the extraordinary development of nanomaterials in different fields of medicine, they have found new applications. Phototherapy modalities, such as photothermal therapy (PTT) by toxic heat generation and photodynamic therapy (PDT) by reactive oxygen species, are known as promising phototherapeutic techniques, which can overcome the limitations of conventional protocols. Moreover, nanomaterial-based PDT and PTT match the simultaneous immune therapy and increase the immune system stimulation resulting from the denaturation of cancer cells. Nevertheless, nanomaterials should have sufficient biocompatibility and efficiency to meet PDT and PTT requirements as therapeutic agents. The present review focuses on the therapeutic potency of PDT, PTT, and also their combined modalities, which are known alternative protocols with minimal morbidity integrated into gold standard treatments such as surgery, chemotherapy, and radiation therapy at tumor treatment and cancer-related infectious diseases. In addition, for deeper understanding, photoablation effects with emphasis on the nature, morphology, and size of photosensitive nanomaterials in PDT and PTT were studied. Finally, transportation techniques and moieties needed as carriers of photosensitizers and photothermal therapy agents to hard-accessed regions, for example, cancerous regions, were investigated.

Recent Advancements in Mitochondria-Targeted Nanoparticle Drug Delivery for Cancer Therapy

Mitochondria are critical subcellular organelles that produce most of the adenosine triphosphate (ATP) as the energy source for most eukaryotic cells. Moreover, recent findings show that mitochondria are not only the "powerhouse" inside cells, but also excellent targets for inducing cell death via apoptosis that is mitochondria-centered. For several decades, cancer nanotherapeutics have been designed to specifically target mitochondria with several targeting moieties, and cause mitochondrial dysfunction via photodynamic, photothermal, or/and chemo therapies. These strategies have been shown to augment the killing of cancer cells in a tumor while reducing damage to its surrounding healthy tissues. Furthermore, mitochondria-targeting nanotechnologies have been demonstrated to be highly efficacious compared to non-mitochondria-targeting platforms both in vitro and in vivo for cancer therapies. Moreover, mitochondria-targeting nanotechnologies have been intelligently designed and tailored to the hypoxic and slightly acidic tumor microenvironment for improved cancer therapies. Collectively, mitochondria-targeting may be a promising strategy for the engineering of nanoparticles for drug delivery to combat cancer.

Engineering Electronic Band Structure of Binary Thermoelectric Nanocatalysts for Augmented Pyrocatalytic Tumor Nanotherapy

Photothermal therapy (PTT) has emerged as a distinct therapeutic modality owing to its noninvasiveness and spatiotemporal selectivity. However, heat-shock proteins (HSPs) endow tumor cells with resistance to heat-induced apoptosis, severely lowering the therapeutic efficacy of PTT. Here, a high-performance pyroelectric nanocatalyst, Bi₁₃ S₁₈ I₂ nanorods (NRs), with prominent pyroelectric conversion and photothermal conversion performance for augmented pyrocatalytic tumor nanotherapy, is developed. Canonical binary compounds are reconstructed by inserting a third biocompatible agent, thus facilitating the formation of Bi₁₃ S₁₈ I₂ NRs with enhanced pyrocatalytic conversion efficiency. Under 808 nm laser irradiation, Bi₁₃ S₁₈ I₂ NRs induce a conspicuous temperature elevation for photonic hyperthermia. In particular, Bi₁₃ S₁₈ I₂ NRs harvest pyrocatalytic energy from the heating and cooling alterations to produce abundant reactive oxygen species, which results in the depletion of HSPs and hence the reduction of thermoresistance of tumor cells, thereby significantly augmenting the therapeutic efficacy of photothermal tumor hyperthermia. By synergizing the pyroelectric dynamic therapy with PTT, tumor suppression with a significant tumor inhibition rate of 97.2% is achieved after intravenous administration of Bi₁₃ S₁₈ I₂ NRs and subsequent exposure to an 808 nm laser. This work opens an avenue for the design of high-performance pyroelectric nanocatalysts by reconstructing canonical binary compounds for therapeutic applications in biocatalytic nanomedicine.

Symphony of nanomaterials and immunotherapy based on the cancer-immunity cycle

The immune system is involved in the initiation and progression of cancer. Research on cancer and immunity has contributed to the development of several clinically successful immunotherapies. These immunotherapies often act on a single step of the cancer–immunity cycle. In recent years, the discovery of new nanomaterials has dramatically expanded the functions and potential applications of nanomaterials. In addition to acting as drug-delivery platforms, some nanomaterials can induce the immunogenic cell death (ICD) of cancer cells or regulate the profile and strength of the immune response as immunomodulators. Based on their versatility, nanomaterials may serve as an integrated platform for multiple drugs or therapeutic strategies, simultaneously targeting several steps of the cancer–immunity cycle to enhance the outcome of anticancer immune response. To illustrate the critical roles of nanomaterials in cancer immunotherapies based on cancer–immunity cycle, this review will comprehensively describe the crosstalk between the immune system and cancer, and the current applications of nanomaterials, including drug carriers, ICD inducers, and immunomodulators. Moreover, this review will provide a detailed discussion of the knowledge regarding developing combinational cancer immunotherapies based on the cancer–immunity cycle, hoping to maximize the efficacy of these treatments assisted by nanomaterials.

IR-808 loaded nanoethosomes for aggregation-enhanced synergistic transdermal photodynamic/photothermal treatment of hypertrophic scars

Synergistic transdermal photodynamic therapy (PDT)/photothermal therapy (PTT) has emerged as a novel strategy for improving hypertrophic scar (HS) therapeutic outcomes. Herein, a near-infrared heptamethine cyanine dye, named IR-808, has been selected as the desirable photosensitizer owing to its PDT and PTT properties. Benefitting from the transdermal delivery ability of ethosomes (ESs), IR-808 loaded nanoethosomes (IR-808-ES) have been prepared as a novel nanophotosensitizer for the transdermal PDT/PTT of HSs. The special structure of IR-808 aggregate distribution in the ES lipid membrane enhances ROS generation and hyperthermia. The in vitro experiments indicate that the IR-808-ES enhances the PDT/PTT efficacy for inducing the HS fibroblast (HSF) apoptosis via the intrinsic mitochondrial pathway. Furthermore, the in vivo transdermal delivery studies reveal that the IR-808-ES efficiently delivers IR-808 into HSFs in the HS tissue. Systematic assessments in the rabbit ear HS models demonstrate that the enhanced PDT/PTT performance of the IR-808-ES has remarkable therapeutic effects on improving the HS appearance, promoting HSF apoptosis and remodeling collagen fibers. Therefore, the IR-808-ES integrates both the transdermal delivery ability and the aggregation-enhanced PDT/PTT effect, and these features endow the IR-808-ES with significant potential as a novel nanophotosensitizer for the transdermal phototherapy of HSs in the clinical field.

Nanomedicine potentiates mild photothermal therapy for tumor ablation

The booming photothermal therapy (PTT) has achieved great progress in non-invasive oncotherapy, and paves a novel way for clinical oncotherapy. Of note, mild temperature PTT (mPTT) of 42–45 °C could avoid treatment bottleneck of the traditional PTT, including nonspecific injury to normal tissues, vasculature and host antitumor immunity. However, cancer cells can resist mPTT via heat shock response and autophagy, thus leading to insufficient mPTT monotherapy to ablate tumor. To overcome the deficient antitumor efficacy caused by thermo-resistance of cancer cells and mono mPTT, synergistic therapies towards cancer cells have been conducted with mPTT. This review summarizes the recent advances in nanomedicine-potentiated mPTT for cancer treatment, including strategies for enhanced single-mode mPTT and mPTT plus synergistic therapies. Moreover, challenges and prospects for clinical translation of nanomedicine-potentiated mPTT are discussed.

Molecularly engineered carrier-free co-delivery nanoassembly for self-sensitized photothermal cancer therapy

BACKGROUND

Photothermal therapy (PTT) has been extensively investigated as a tumor-localizing therapeutic modality for neoplastic disorders. However, the hyperthermia effect of PTT is greatly restricted by the thermoresistance of tumor cells. Particularly, the compensatory expression of heat shock protein 90 (HSP90) has been found to significantly accelerate the thermal tolerance of tumor cells. Thus, a combination of HSP90 inhibitor and photothermal photosensitizer is expected to significantly enhance antitumor efficacy of PTT through hyperthermia sensitization. However, it remains challenging to precisely co-deliver two or more drugs into tumors.

METHODS

A carrier-free co-delivery nanoassembly of gambogic acid (GA, a HSP90 inhibitor) and DiR is ingeniously fabricated based on a facile and precise molecular co-assembly technique. The assembly mechanisms, photothermal conversion efficiency, laser-triggered drug release, cellular uptake, synergistic cytotoxicity of the nanoassembly are investigated in vitro. Furthermore, the pharmacokinetics, biodistribution and self-enhanced PTT efficacy were explored in vivo.

RESULTS

The nanoassembly presents multiple advantages throughout the whole drug delivery process, including carrier-free fabrication with good reproducibility, high drug co-loading efficiency with convenient dose adjustment, synchronous co-delivery of DiR and GA with long systemic circulation, as well as self-tracing tumor accumulation with efficient photothermal conversion. As expected, HSP90 inhibition-augmented PTT is observed in a 4T1 tumor BALB/c mice xenograft model.

CONCLUSION

Our study provides a novel and facile dual-drug co-assembly strategy for self-sensitized cancer therapy.

Integrin αvβ3-targeted polydopamine-coated gold nanostars for photothermal ablation therapy of hepatocellular carcinoma

Photothermal therapy (PTT) has emerged as a promising cancer therapeutic method. In this study, Arg-Gly-Asp (RGD) peptide-conjugated polydopamine-coated gold nanostars (Au@PDA-RGD NPs) were prepared for targeting PTT of hepatocellular carcinoma (HCC). A polydopamine (PDA) shell was coated on the surface of gold nanostars by the oxidative self-polymerization of dopamine (termed as Au@PDA NPs). Au@PDA NPs were further functionalized with polyethylene glycol and RGD peptide to improve biocompatibility as well as selectivity toward the HCC cells. Au@PDA-RGD NPs showed an intense absorption at 822 nm, which makes them suitable for near-infrared-excited PTT. Our results indicated that the Au@PDA-RGD NPs were effective for the PTT therapy of the α_Vβ₃ integrin receptor-overexpressed HepG2 cells in vitro. Further antitumor mechanism studies showed that the Au@PDA-RGD NPs-based PTT induced human liver cancer cells death via the mitochondrial–lysosomal and autophagy pathways. In vivo experiments showed that Au@PDA-RGD NPs had excellent tumor treatment efficiency and negligible side effects. Thus, our study showed that Au@PDA-RGD NPs could offer an excellent nanoplatform for PTT of HCC.

Modulation of Cancer Cell Autophagic Responses by Graphene-Based Nanomaterials: Molecular Mechanisms and Therapeutic Implications

Simple Summary

Graphene-based nanomaterials (GNM) are one-to-several carbon atom-thick flakes of graphite with at least one lateral dimension <100 nm. The unique electronic structure, high surface-to-volume ratio, and relatively low toxicity make GNM potentially useful in cancer treatment. GNM such as graphene, graphene oxide, graphene quantum dots, and graphene nanofibers are able to induce autophagy in cancer cells. During autophagy the cell digests its own components in organelles called lysosomes, which can either kill cancer cells or promote their survival, as well as influence the immune response against the tumor. However, a deeper understanding of GNM-autophagy interaction at the mechanistic and functional level is needed before these findings could be exploited to increase GNM effectiveness as cancer therapeutics and drug delivery systems. In this review, we analyze molecular mechanisms of GNM-mediated autophagy modulation and its possible implications for the use of GNM in cancer therapy.

Abstract

Graphene-based nanomaterials (GNM) are plausible candidates for cancer therapeutics and drug delivery systems. Pure graphene and graphene oxide nanoparticles, as well as graphene quantum dots and graphene nanofibers, were all able to trigger autophagy in cancer cells through both transcriptional and post-transcriptional mechanisms involving oxidative/endoplasmic reticulum stress, AMP-activated protein kinase, mechanistic target of rapamycin, mitogen-activated protein kinase, and Toll-like receptor signaling. This was often coupled with lysosomal dysfunction and subsequent blockade of autophagic flux, which additionally increased the accumulation of autophagy mediators that participated in apoptotic, necrotic, or necroptotic death of cancer cells and influenced the immune response against the tumor. In this review, we analyze molecular mechanisms and structure–activity relationships of GNM-mediated autophagy modulation, its consequences for cancer cell survival/death and anti-tumor immune response, and the possible implications for the use of GNM in cancer therapy.

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.

Solutions to the Drawbacks of Photothermal and Photodynamic Cancer Therapy

Phototherapy such as photothermal therapy and photodynamic therapy in cancer treatment has been developed quickly over the past few years for its noninvasive nature and high efficiency. However, there are still many drawbacks in phototherapy that prevent it from clinical applications. Thus, scientists have designed different systems to overcome the issues associated with phototherapy, including enhancing the targeting ability of phototherapy, low-temperature photothermal therapy, replacing near-infrared light with other excitation sources, and so on. This article discusses the problems and shortcomings encountered in the development of phototherapy and highlights possible solutions to address them so that phototherapy may become a useful cancer treatment approach in clinical practice. This article aims to give a brief summary about current research advancements in phototherapy research and provides a quick guideline toward future developments in the field.

Antitumorigenic Effect of Hsp90 Inhibitor SNX-2112 on Tongue Squamous Cell Carcinoma is Enhanced by Low-Intensity Ultrasound

Purpose

The novel Hsp90 inhibitor SNX-2112 showed broad antitumor activity. However, it was still necessary to optimize the therapeutic dosage of SNX-2112 applied on tumors to obtain effective therapy with minimal dose to reduce toxicity. We investigated the role of low-intensity US in promoting antitumorigenic effect of low doses of SNX-2112 on tongue squamous cell carcinoma.

Methods

Cell viability was measured using CCK-8 assay or staining with Calcein AM/PI. Relative cumulative levels of SNX-2112 in cells were detected using high-performance liquid chromatography. The production of ROS was analyzed using fluorescence microscope and flow cytometer. Cellular apoptosis was detected using flow cytometer. The expression levels of proteins of the ERS-associated apoptosis signaling pathway were detected using Western blotting analysis. The efficacy and biosafety of SNX-2112 were also investigated in a mouse xenograft model.

Results

Low-intensity US combined with SNX-2112 exhibited significant antitumor effect, increased the absorption of SNX-2112 by cells even with a low dose, enhanced ROS generation and apoptosis. The combination regimen also inhibited the protein expression of Hsp90 and triggered apoptosis through endoplasmic reticulum stress (ERS) by enhancing PERK, CHOP and Bax protein levels, while downregulating the level of Bcl-2. Additionally, N-acetyl-L-cysteine (NAC), ROS scavenger, was able to reverse these results. Low-intensity US combined with SNX-2112 significantly inhibited tumor growth, prolonged survival of mice, decreased proliferation and promoted apoptosis with no visible damage or abnormalities in major organs in the mouse xenograft model with tongue squamous cell carcinoma.

Conclusion

The antitumor effects of SNX-2112 were enhanced by low-intensity US. The most probable mechanism was that US sonoporation induced more SNX-2112 delivery to the cells and enhanced ROS production, triggering the ERS-associated apoptosis signaling pathway. Therefore, low-intensity US may increase the efficiency of conventional chemotherapy and reduce the dosage of SNX-2112 required and its side effects.

Hydroxysafflor yellow A induces autophagy in human liver cancer cells by regulating Beclin 1 and ERK expression

Hydroxysafflor yellow A (HSYA) is a water-soluble component of the safflower (Carthamus tinctorius), and research has revealed that HSYA exhibits antitumor effects. In the present study, the effects of HSYA on the autophagy of a Hep-G2 liver cancer cell line, as well as the underlying mechanisms, were investigated. Hep-G2 cells were treated with HSYA and the viability of cells was measured using an MTT assay. Western blotting and immunofluorescence assays were performed to determine the expression of light chain 3 II (LC3-II) and p62, as well as the autophagy regulators Beclin 1 and ERK1/2. Transmission electron microscopy was performed to observe the formation of autophagosomes. The combined effects of HSYA and the autophagy inhibitor chloroquine (CQ) were also determined. The results revealed that the viability of Hep-G2 cells decreased with increasing concentrations of HSYA. Furthermore, LC3-II expression increased significantly and the level of p62 decreased significantly in the HYSA group compared with the control group. Additionally, an increase in Beclin 1 expression and a decrease in phosphorylated-ERK1/2 expression was observed in Hep-G2 cells treated with HYSA. Following treatment with CQ and HSYA, a significant increase in the viability of Hep-G2 cells was observed compared with the HSYA group. Collectively, the results indicated that HSYA induced autophagy by promoting the expression of Beclin 1 and inhibiting the phosphorylation of ERK in liver cancer cells. Therefore, HSYA may serve as a potential therapeutic agent for liver cancer.