Self-Distinguishing and Stimulus-Responsive Carrier-Free Theranostic Nanoagents for Imaging-Guided Chemo-Photothermal Therapy in Small-Cell Lung Cancer

Advances and challenges in the treatment of lung cancer

Lung cancer accounts for a relatively high proportion of malignant tumors. As the most prevalent type of lung cancer, non-small cell lung cancer (NSCLC) is characterized by high morbidity and mortality. Presently, the arsenal of treatment strategies encompasses surgical resection, chemotherapy, targeted therapy and radiotherapy. However, despite these options, the prognosis remains distressingly poor with a low 5-year survival rate. Therefore, it is urgent to pursue a paradigm shift in treatment methodologies. In recent years, the advent of sophisticated biotechnologies and interdisciplinary integration has provided innovative approaches for the treatment of lung cancer. This article reviews the cutting-edge developments in the nano drug delivery system, molecular targeted treatment system, photothermal treatment strategy, and immunotherapy for lung cancer. Overall, by systematically summarizing and critically analyzing the latest progress and current challenges in these treatment strategies of lung cancer, we aim to provide a theoretical basis for the development of novel drugs for lung cancer treatment, and thus improve the therapeutic outcomes for lung cancer patients.

GSH-Responsive Prodrug Nanoassembly as a Carrier-Free Nanoplatform for Tumor-Targeting Delivery and Chemo-Photothermal Therapy

Photothermal therapy, combined with chemotherapy, holds promising prospects for the therapeutic outcome of malignant tumors. However, the synergistic therapeutic effect suffers from low coloading capacity and inefficient synchronous tumor-targeting delivery of chemodrug and photothermal photosensitizers. Herein, we designed a versatile carrier-free nanoplatform to seek improvement for chemo-photothermal therapy. An NIR photosensitizer IR-808 was used for noninvasive cancer imaging, diagnosis, and imaging-guided photothermal therapy. A reduction-sensitive paclitaxel prodrug (PTX-SS-PEG2k) was rationally synthesized by covalently linking paclitaxel with polyethylene glycol 2000 via a disulfide bond. Then, the carrier-free nanoassemblies were constructed with an inner core of IR-808 and an amphiphilic paclitaxel prodrug shell. PTX-SS-PEG2k served as a stabilizer and chemodrug and could facilitate the self-assembly of IR-808 nanoparticles with high coloading efficiency and reduction-sensitive drug release. The versatile nanoplatform exhibited multiple advantages, including high drug payload, reduction-sensitive drug release, tumor-targeting drug delivery, and potent synergistic antitumor effect. We provide a versatile theranostic nanoplatform, which improves the effectiveness of synergetic chemo-photothermal therapy and reduces the off-target toxicity.

Cancer Cell-Specific Fluorescent Prodrug Delivery Platforms

Targeting cancer cells with high specificity is one of the most essential yet challenging goals of tumor therapy. Because different surface receptors, transporters, and integrins are overexpressed specifically on tumor cells, using these tumor cell-specific properties to improve drug targeting efficacy holds particular promise. Targeted fluorescent prodrugs not only improve intracellular accumulation and bioavailability but also report their own localization and activation through real-time changes in fluorescence. In this review, efforts are highlighted to develop innovative targeted fluorescent prodrugs that efficiently accumulate in tumor cells in different organs, including lung cancer, liver cancer, cervical cancer, breast cancer, glioma, and colorectal cancer. The latest progress and advances in chemical design and synthetic considerations in fluorescence prodrug conjugates and how their therapeutic efficacy and fluorescence can be activated by tumor-specific stimuli are reviewed. Additionally, novel perspectives are provided on strategies behind engineered nanoparticle platforms self-assembled from targeted fluorescence prodrugs, and how fluorescence readouts can be used to monitor the position and action of the nanoparticle-mediated delivery of therapeutic agents in preclinical models. Finally, future opportunities for fluorescent prodrug-based strategies and solutions to the challenges of accelerating clinical translation for the treatment of organ-specific tumors are proposed.

Carbonic anhydrase IX-targeted nanovesicles potentiated ferroptosis by remodeling the intracellular environment for synergetic cancer therapy

Ferroptosis is one critical kind of regulated cell death for tumor suppression, yet it still presents challenges of low efficiency due to the intracellular alkaline pH and aberrant redox status. Herein, we reported a carbonic anhydrase IX (CA IX)-targeted nanovesicle (PAHC NV) to potentiate ferroptosis by remodeling the intracellular environment. CA IX inhibitor 4-(2-aminoethyl) benzene sulfonamide (AEBS) was anchored onto nanovesicles loaded with hemoglobin (Hb) and chlorin e6 (Ce6). Upon reaching tumor regions, PAHC could be internalized by cancer cells specifically by means of CA IX targeting and intervention. Afterwards, the binding of AEBS could elicit intracellular acidification and alter redox homeostasis to boost the lipid peroxidation (LPO) level, thus aggravating the ferroptosis process. Meanwhile, Hb served as an iron reservoir that could efficiently evoke ferroptosis and release O₂ to ameliorate tumor hypoxia. With the help of self-supplied O₂, Ce6 produced a plethora of ¹O₂ for enhanced photodynamic therapy, which in turn favored LPO accumulation to synergize ferroptosis. This study presents a promising paradigm for designing nanomedicines to heighten ferroptosis-based synergetic therapeutics through remodeling the intracellular environment.

A Self-Assembly ICG Nanoparticle Potentiating Targeted Photothermal and Photodynamic Therapy in NSCLC

In nonsmall cell lung cancers (NSCLC), near-infrared (NIR) fluorescence imaging using indocyanine green (ICG) has proven to be an efficient approach for locating pulmonary nodules and pulmonary sentinel lymph nodes. However, due to a lack of tumor selectivity, ICG's use as a photosensitizer for photothermal therapy (PTT) and photodynamic therapy (PDT) is restricted. In the current study, we aimed to develop a type of high-performance NIR nanoparticle formulated with ICG to enhance its targeted efficacy and tumor specificity on NSCLC. An ICG-osimertinib nanoparticle (ICG-Osi) was self-assembled through π-π stacking, with a size of 276 nm and a surface charge of -7.4 mV. The NIR visibility and epidermal growth factor receptor (EGFR) targetability of the ICG-Osi was confirmed by its binding efficiency to EGFR-expressing NSCLC cells in vitro and in vivo, regardless of EGFR mutation status. The targeted effect was further confirmed in mouse xenograft models and showed an extended tumor retention time (>96 h). We demonstrated a significantly enhanced hyperthermia effect and a retained reactive oxygen species (ROS) generating ability of ICG-Osi, resulting in a 2-fold higher cell death rate than ICG alone. The ICG-Osi down-regulated GPX4 and p62 expression while up-regulating caspase-3 and beclin1 expression in NSCLC cells, indicating a complex network of cell death-related proteins. Considering the merits of simple assembly, EGFR binding efficacy, improved hyperthermia effect, and efficient cancer cell suppression, the ICG-Osi exhibits great potential for clinical application in EGFR-expressing NSCLC therapy.

pH/Thermal-Sensitive Nanoplatform Capable of On-Demand Specific Release to Potentiate Drug Delivery and Combinational Hyperthermia/Chemo/Chemodynamic Therapy

Therapeutic platforms with spatiotemporal control were recently of considerable interest. However, the site-specific regulation of chemotherapeutics release remains an enormous challenge. Herein, a versatile nanoplatform capable of tumor-specific delivery and controlled drug release, coined as PDDFe, was constructed for elevating cancer theranostics. Iron-oxide nanoparticles (IONPs) and doxorubicin (Dox) were encapsulated in pH/thermal-sensitive micelles composed of poly(ethylene)glycol-poly(β-amino esters) and dipalmitoyl phosphatidylcholine to obtain tumor-targeted dual-responsive nanoplatforms. With remarkable magnetic targeting effects, PDDFe specifically accumulated at tumor locations. After internalization by cancer cells, the acidic environment and localized heat generated by hyperthermia therapy would spur PDDFe to become loose and collapse to liberate its payload. In addition to boosting the release, the increased temperature also resulted in direct tumor damage. Meanwhile, the released Dox and IONPs, respectively, stimulated chemotherapy and chemodynamic therapy to jointly destroy cancer, thus leading to a pronounced therapeutic effect. In vivo magnetic resonance/fluorescence/photoacoustic imaging experiments validated that the dual-sensitive nanoplatforms were able to accumulate at the tumor sites. Treatment with PDDFe followed by alternating magnetic field and laser irradiation could prime hyperthermia/chemo/chemodynamic therapy to effectively retard tumor growth. This work presents a nanoplatform with a site-specific controlled release characteristic, showing great promises in potentiating drug delivery and advancing combinational cancer therapy.

Targeted contrast agents and activatable probes for photoacoustic imaging of cancer

Photoacoustic (PA) imaging has emerged as a powerful technique for the high resolution visualization of biological processes within deep tissue. Through the development and application of exogenous targeted contrast agents and activatable probes that can respond to a given cancer biomarker, researchers can image molecular events in vivo during cancer progression. This information can provide valuable details that can facilitate cancer diagnosis and therapy monitoring. In this tutorial review, we provide a step-by-step guide to select a cancer biomarker and subsequent approaches to design imaging agents for in vivo use. We envision this information will be a useful summary to those in the field, new members to the community, and graduate students taking advanced imaging coursework. We also highlight notable examples from the recent literature, with emphasis on the molecular designs and their in vivo PA imaging performance. To conclude, we provide our outlook and future perspective in this exciting field.

Stimuli-Responsive Drug Delivery Systems for the Diagnosis and Therapy of Lung Cancer

Lung cancer is the most commonly diagnosed cancer and the leading cause of cancer death worldwide. Numerous drugs have been developed to treat lung cancer patients in recent years, whereas most of these drugs have undesirable adverse effects due to nonspecific distribution in the body. To address this problem, stimuli-responsive drug delivery systems are imparted with unique characteristics and specifically deliver loaded drugs at lung cancer tissues on the basis of internal tumor microenvironment or external stimuli. This review summarized recent studies focusing on the smart carriers that could respond to light, ultrasound, pH, or enzyme, and provided a promising strategy for lung cancer therapy.

Chelerythrine inhibits the progression of glioblastoma by suppressing the TGFB1-ERK1/2/Smad2/3-Snail/ZEB1 signaling pathway

AIMS

Glioblastoma (GBM) is the most common and aggressive intracranial tumor with poor prognosis. A large majority of clinical chemotherapeutic agents cannot achieve the desired therapeutic effect. Chelerythrine (CHE), a natural component with multitudinous pharmacological functions, has been proven to have outstanding antitumor effects in addition to antibacterial, anti-inflammatory, and hypotensive effects. However, the anti-GBM effect of CHE has not been reported to date. The purpose of this paper is to observe the anti-GBM effect of CHE and further explore the related mechanism.

MATERIALS AND METHODS

GBM cell lines (U251 and T98G) and BALB/c nude mice were used in the experiments. Methyl thiazolyl tetrazolium (MTT) and clone formation assays were applied to detect the viability, proliferation and stemness of GBM cells. Flow cytometry was utilized to identify the effect of CHE on GBM apoptosis. Scratch and Transwell experiments reflected the migration and invasion of cells. In vivo, xenograft tumors were implanted subcutaneously in nude mice. The progression of tumors was assessed by ultrasound and magnetic resonance imaging. Finally, western blot, bioinformatics, and immunohistochemistry experiments were used to explore the molecular mechanisms in depth.

KEY FINDINGS

In vitro tests showed that CHE inhibited the proliferation, stemness, migration, and invasion of GBM cells and induced apoptosis. In vitro, CHE was observed to restrain the progression of xenograft tumors. We eventually proved that the cytotoxicity of CHE was relevant to the TGFB1-ERK1/2/Smad2/3-Snail/ZEB1 signaling pathway.

SIGNIFICANCE

CHE inhibited GBM progression by inhibiting the TGFB1-ERK1/2/Smad2/3-Snail/ZEB1 signaling pathway and is a potential chemotherapeutic drug for GBM.

A carrier-free supramolecular nanoprodrug based on lactose-functionalized dimeric camptothecin via self-assembly in water for targeted and fluorescence imaging-guided chemo-photodynamic therapy

Most carrier-based nano drug delivery systems (nano-DDSs) are subjected to complex preparation or purification processes, metabolic instability and potential systemic toxicity. To overcome these issues, it is urgent to develop a multifunctional carrier-free nano-DDS that can be fabricated by a simple approach for enhanced anticancer efficacy. In this work, the carrier-free supramolecular nanoprodrug (CF SNPD) based on lactose (Lac) functionalized dimeric camptothecin (CPT) was developed, in which Lac and CPT were conjugated by the aromatized thioacetal (ATA, a reactive oxygen species (ROS)-responsive bond). The obtained Lac-ATA-CPT₂ prodrug and the photosensitizer Chlorin e6 (Ce6) formed CF SNPD (denoted as Ce6@Lac-ATA-CPT₂ NPs) in water by supramolecular self-assembly. The design of dimeric CPT endowed Ce6@Lac-ATA-CPT₂ NPs with ultrahigh drug-loading capacity (up to 94%) and excellent stability. The Lac-functionalized CF SNPD displayed active specific targetability to HepG2 cells resulting from the carbohydrate-protein interactions. Furthermore, the fluorescence signal of Ce6 facilitated the precise tracking and localization of Ce6@Lac-ATA-CPT₂ NPs within the cell. Meanwhile, the ROS generated by Ce6 not only cleaved ATA linker to trigger on-demand CPT release, but also exhibited a killing effect on tumor cells, enabling synergistic therapy via CPT-mediated chemotherapy (CT) and Ce6-induced photodynamic therapy (PDT). Therefore, the multifunctional CF SNPD may be one of the promising therapeutic options for liver cancer.

H2O2 Self-Supplying and GSH-Depleting Nanoplatform for Chemodynamic Therapy Synergetic Photothermal/Chemotherapy

Chemodynamic therapy (CDT) that utilizes Fenton-type reactions to convert endogenous hydrogen peroxide (H₂O₂) into hydroxyl radicals (^•OH) is a promising strategy in anticancer treatment, but the overexpression of glutathione (GSH) and limited endogenous H₂O₂ make the efficiency of CDT unsatisfactory. Here, an intelligent nanoplatform CuO₂@mPDA/DOX-HA (CPPDH), which induced the depletion of GSH and the self-supply of H₂O₂, was proposed. When CPPDH entered tumor cells through the targeting effect of hyaluronic acid (HA), a release of Cu²⁺ and produced H₂O₂ were triggered by the acidic environment of lysosomes. Then, the Cu²⁺ was reduced by GSH to Cu⁺, and the Cu⁺ catalyzed H₂O₂ to produce ^•OH. The generation of ^•OH could be distinctly enhanced by the GSH depletion and H₂O₂ self-sufficiency. Besides, an outstanding photothermal therapy (PTT) effect could be stimulated by NIR irradiation on mesoporous polydopamine (mPDA). Meanwhile, mPDA was an excellent photoacoustic reagent, which could monitor the delivery of nanocomposite materials through photoacoustic (PA) imaging. Moreover, the successful delivery of doxorubicin (DOX) realized the integration of chemotherapy, PTT, and CDT. This strategy could solve the problem of insufficient CDT efficacy caused by the limited H₂O₂ and overexpression of GSH. This multifunctional nanoplatform may open a broad path for self-boosting CDT and synergistic therapy.

A carrier-free nanoparticle with dual NIR/acid responsiveness by co-assembly of enediyne and IR820 for combined PTT/chemotherapy

Combined photothermal therapy/chemotherapy by co-delivery of a photosensitizer (PS) and a chemotherapeutic drug has demonstrated great potential for cancer treatment. The intrinsic drawbacks of traditional drug delivery systems (DDSs), such as tedious synthetic procedures, side effects originated from the carrier materials, low loading efficiency, and uncontrolled drug release, however, have impaired their further advancement. On the other hand, enediyne antibiotics are highly cytotoxic toward cancer cells through the generation of lethal carbon radicals via thermal-induced cyclization, endowing them with great potential to achieve enhanced synergistic anticancer performance by incorporation with the photothermal effect of PS. To this end, a carrier-free and NIR/acid dual-responsive DDS was constructed for combined photothermal therapy/chemotherapy. The facile co-assembly of maleimide-based enediyne and PS IR820 was achieved in aqueous solution to give nanoparticles (EICN) with a hydrodynamic diameter of 90 nm and high stability. In vitro study confirmed the acid/NIR dual-responsive degradation and drug release, free radical generation and DNA-cleaving ability of EICN, which was accomplished by the corporation of enediyne and IR820 moieties. Further tests on HeLa cells verified the excellent synergistic anticancer performance of EICN including the improved cellular uptake, NIR-enhanced drug release, DNA damage and histone deacetylase inhibitor capacity. Overall, this carrier-free DDS with dual acid/NIR-responsivity would potentially provide new insights for the development of combined photothermal/chemotherapy.

Self-targeting nanotherapy based on functionalized graphene oxide for synergistic thermochemotherapy

Nanotherapy based on thermochemotherapy has boomed as a promising alternative for oncotherapy due to the enhanced permeability and retention (EPR) effect. However, a lack of self-targeting capacity prevents nanotherapy from efficiently accumulating in tumor tissue and internalizing into tumor cells, resulting in a suboptimal therapeutic effect. To overcome these bottlenecks, a kind of methotrexate (MTX)-soybean phospholipid (SPC) inclusion complex (MTX-SPC)-modified graphene oxide (CGO) nanotherapy (CGO-MTX-SPC) is constructed by CGO nanosheets as a supporter for MTX-SPC, thereby realizing active-targeting and synergistic thermochemotherapy. As an FDA-approved chemotherapeutic drug, MTX can be regarded as a tumor-targeting enhancer against the folate receptor on account of its similar structure to folic acid (FA). The fabricated CGO-MTX-SPC has a sheet shape with a size of ca. 109 nm and tumor microenvironment-responsive on-demand drug release. It is worth noting that the physiological stability of CGO-MTX-SPC is better than that of CGO while displaying an improved photothermal effect. In addition, CGO-MTX-SPC can specifically recognize tumor cells and then achieve on-demand drug burst release by dual stimuli of internal lysosomal acidity and an external laser. Moreover, in vivo experimental results further demonstrate that CGO-MTX-SPC displays significant enrichment at the tumor location by active targeting mechanisms due to the introduction of MTX-SPC, endowing the synergistic thermochemotherapy effect upon 808 nm laser irradiation and almost thorough tumor elimination while significantly erasing undesirable side effects. Taken together, the design idea of our nanotherapy not only provides a potential tumor-targeting therapeutic strategy but also broadens the drug payload method of two-dimensional nanomaterials.

Advances in Indocyanine Green-Based Codelivery Nanoplatforms for Combinatorial Therapy

Indocyanine green (ICG), a near-infrared (NIR) agent with an excellent imaging performance, has captivated enormous interest from researchers owing to its excellent therapeutic and imaging abilities. Although various nanoplatforms-based drug delivery systems (DDS) with the ability to overcome the clinical limitations of ICG has been reported, ICG-medicated conventional cancer diagnosis and photorelated therapies still lack in exhibiting the therapeutic efficacy, resulting in incomplete or partly tumor elimination. In the view of addressing these concerns, various DDSs have been engineered for the efficient codelivery of combined therapeutic agents with ICG, aiming to achieve promising therapeutic results due to multifunctional imaging-guided synergistic antitumor effects. In this article, we will systematically review currently available nanoplatforms based on polymers, inorganic, proteins, and metal-organic frameworks (MOFs), among others, for codelivery of ICG along with other therapeutic agents, providing a foundation for future clinical development of ICG. In addition, codelivery systems for ICG and different mechanism-based therapeutic agents will be illustrated. In summary, we conclude the review with the challenges and perspectives of ICG-based versatile nanoplatforms in detail.

Polydopamine-Coated Laponite Nanoplatforms for Photoacoustic Imaging-Guided Chemo-Phototherapy of Breast Cancer

Theranostic nanoplatforms combining photosensitizers and anticancer drugs have aroused wide interest due to the real-time photoacoustic (PA) imaging capability and improved therapeutic efficacy by the synergistic effect of chemotherapy and phototherapy. In this study, polydopamine (PDA) coated laponite (LAP) nanoplatforms were synthesized to efficiently load indocyanine green (ICG) and doxorubicin (DOX), and modified with polyethylene glycol-arginine-glycine-aspartic acid (PEG-RGD) for PA imaging-guided chemo-phototherapy of cancer cells overexpressing α_vβ₃ integrin. The formed ICG/LAP-PDA-PEG-RGD/DOX nanoplatforms showed significantly higher photothermal conversion efficiency than ICG solution and excellent PA imaging capability, and could release DOX in a pH-sensitive and NIR laser-triggered way, which is highly desirable feature in precision chemotherapy. In addition, the ICG/LAP-PDA-PEG-RGD/DOX nanoplatforms could be uptake by cancer cells overexpressing α_vβ₃ integrin with high specificity, and thus serve as a targeted contrast agent for in vivo PA imaging of cancer. In vivo experiments with 4T1 tumor-bearing mouse model demonstrated that ICG/LAP-PDA-PEG-RGD/DOX nanoplatforms exhibited much stronger therapeutic effect and higher survival rate than monotherapy due to the synergetic chemo-phototherapy under NIR laser irradiation. Therefore, the reported ICG/LAP-PDA-PEG-RGD/DOX represents a promising theranostic nanoplatform for high effectiveness PA imaging-guided chemo-phototherapy of cancer cells overexpressing α_vβ₃ integrin.