Versatile Nano-PROTAC-Induced Epigenetic Reader Degradation for Efficient Lung Cancer Therapy

Bromodomain and Extraterminal Domain Protein 2 in Multiple Human Diseases

Bromodomain and extraterminal domain protein 2 (BRD2), a member of the bromodomain and extraterminal domain (BET) protein family, is a crucial epigenetic regulator with significant function in various diseases and cellular processes. The central function of BRD2 is modulating gene transcription by binding to acetylated lysine residues on histones and transcription factors. This review highlights key findings on BRD2 in recent years, emphasizing its roles in maintaining genomic stability, influencing chromatin spatial organization, and participating in transcriptional regulation. BRD2's diverse functions are underscored by its involvement in diseases such as malignant tumors, neurologic disorders, inflammatory conditions, metabolic diseases, and virus infection. Notably, the potential role of BRD2 as a diagnostic marker and therapeutic target is discussed in the context of various diseases. Although pan inhibitors targeting the BET family have shown promise in preclinical studies, a critical need exists for the development of highly selective BRD2 inhibitors. In conclusion, this review offers insights into the multifaceted nature of BRD2 and calls for continued research to unravel its intricate mechanisms and harness its therapeutic potential. SIGNIFICANCE STATEMENT: BRD2 is involved in the occurrence and development of diseases through maintaining genomic stability, influencing chromatin spatial organization, and participating in transcriptional regulation. Targeting BRD2 through protein degradation-targeting complexes technology is emerging as a promising therapeutic approach for malignant cancer and inflammatory diseases.

Restraining the power of Proteolysis Targeting Chimeras in the cage: A necessary and important refinement for therapeutic safety

Proteolysis Targeting Chimeras (PROTACs) represent a significant advancement in therapeutic drug development by leveraging the ubiquitin-proteasome system to enable targeted protein degradation, particularly impacting oncology. This review delves into the various types of PROTACs, such as peptide-based, nucleic acid-based, and small molecule PROTACs, each addressing distinct challenges in protein degradation. It also discusses innovative strategies like bridged PROTACs and conditional switch-activated PROTACs, offering precise targeting of previously "undruggable" proteins. The potential of PROTACs extends beyond oncology, with ongoing research and technological advancements needed to maximize their therapeutic potential. Future progress in this field relies on interdisciplinary collaboration and the integration of advanced computational tools to open new treatment avenues across various diseases.

Application of PLGA in Tumor Immunotherapy

Biodegradable polymers have been extensively researched in the field of biomedicine. Polylactic-co-glycolic acid (PLGA), a biodegradable polymer material, has been widely used in drug delivery systems and has shown great potential in various medical fields, including vaccines, tissue engineering such as bone regeneration and wound healing, and 3D printing. Cancer, a group of diseases with high mortality rates worldwide, has recently garnered significant attention in the field of immune therapy research. In recent years, there has been growing interest in the delivery function of PLGA in tumor immunotherapy. In tumor immunotherapy, PLGA can serve as a carrier to load antigens on its surface, thereby enhancing the immune system's ability to attack tumor cells. Additionally, PLGA can be used to formulate tumor vaccines and immunoadjuvants, thereby enhancing the efficacy of tumor immunotherapy. PLGA nanoparticles (NPs) can also enhance the effectiveness of tumor immunotherapy by regulating the activity and differentiation of immune cells, and by improving the expression and presentation of tumor antigens. Furthermore, due to the diverse physical properties and surface modifications of PLGA, it has a wider range of potential applications in tumor immunotherapy through the loading of various types of drugs or other innovative substances. We aim to highlight the recent advances and challenges of plga in the field of oncology therapy to stimulate further research and development of innovative PLGA-based approaches, and more effective and personalized cancer therapies.

Sulfatase-Induced In Situ Formulation of Antineoplastic Supra-PROTACs

Proteolysis targeting chimera (PROTAC) technology is an innovative strategy for cancer therapy, which, however, suffers from poor targeting delivery and limited capability for protein of interest (POI) degradation. Here, we report a strategy for the in situ formulation of antineoplastic Supra-PROTACs via intracellular sulfatase-responsive assembly of peptides. Coassembling a sulfated peptide with two ligands binding to ubiquitin VHL and Bcl-xL leads to the formation of a pro-Supra-PROTAC, in which the ratio of the two ligands is rationally optimized based on their protein binding affinity. The resulting pro-Supra-PROTAC precisely undergoes enzyme-responsive assembly into nanofibrous Supra-PROTACs in cancer cells overexpressing sulfatase. Mechanistic studies reveal that the pro-Supra-PROTACs selectively cause apparent cytotoxicity to cancer cells through the degradation of Bcl-xL and the activation of caspase-dependent apoptosis, during which the rationally optimized ligand ratio improves the bioactivity for POI degradation and cell death. In vivo studies show that in situ formulation enhanced the tumor accumulation and retention of the pro-Supra-PROTACs, as well as the capability for inhibiting tumor growth with excellent biosafety when coadministrating with chemodrugs. Our findings provide a new approach for enzyme-regulated assembly of peptides in living cells and the development of PROTACs with high targeting delivering and POI degradation efficiency.

Liposomal STAT3-Degrading PROTAC Prodrugs Promote Anti-Hepatocellular Carcinoma Immunity via Chemically Reprogramming Cancer Stem Cells

Cancer stem cells (CSCs) with hyperactivated signal transducer and activator of transcription 3 (STAT3) are a major driver of hepatocellular carcinoma (HCC). Herein, we report a nanointegrative proteolysis-targeting chimera (PROTAC)-based STAT3 degradation strategy that enables efficient chemical reprogramming of HCC-associated CSCs, which potently inhibits CSC growth while evoking anti-HCC immune responses. The PROTAC prodrug was synthesized by conjugating the STAT3 binding domain (inS3) with a thioketal-caged E3 ligase ligand (VL-TK) via an oligo(ethylene glycol) linker (OEG) with tuned length and flexibility and encapsulating it in cRGD-modified cationic liposomes for CSC-targeted delivery while facilitating their lysosomal escape. The PROTAC prodrugs were activated by the upregulated ROS levels in CSCs and efficiently degraded STAT3 for chemical reprogramming, which would not only impair their stemness features but also remodel the immunosuppressive TME into an immunosupportive state to boost anti-HCC immunity. This strategy provides an approach for improving HCC treatment in clinics.

Apoptotic body-inspired nanotherapeutics efficiently attenuate osteoarthritis by targeting BRD4-regulated synovial macrophage polarization

Bromodomain-containing protein 4 (BRD4) is the most well-studied BET protein that is important for the innate immune response. We recently revealed that targeting BRD4 triggers apoptosis in tumor-associated macrophages, but its role in synovial macrophages and joint inflammation is largely unknown. Herein, we demonstrated that BRD4 was highly expressed in the iNOS-positive M1 macrophages in the human and mouse osteoarthritis (OA) synovium, and conditional knockout of BRD4 in the myeloid lineage using Lyz2-cre; BRD4flox/flox mice significantly abolished anterior cruciate ligament transection (ACLT)-induced M1 macrophage accumulation and synovial inflammation. Accordingly, we successfully constructed apoptotic body-inspired phosphatidylserine-containing nanoliposomes (PSLs) loaded with the BRD4 inhibitor JQ1 to regulate inflammatory macrophages. JQ1-loaded PSLs (JQ1@PSLs) exhibited a higher cellular uptake by macrophages than fibroblast-like synoviocytes (FLSs) in vitro and in vivo, as well as the reduction in proinflammatory M1 macrophage polarization. Intra-articular injections of JQ1@PSLs showed prolonged retention within the joint, and remarkably reduced synovial inflammation and joint pain via suppressing M1 polarization accompanied by reduced TRPA1 expression by targeted inhibition of BRD4 in the macrophages, thus attenuating cartilage degradation during OA development. The results show that BRD4-inhibiting JQ1@PSLs can targeted-modulate macrophage polarization, which opens a new avenue for efficient OA therapy via a "Trojan horse".

Potential of the nanoplatform and PROTAC interface to achieve targeted protein degradation through the Ubiquitin-Proteasome system

In eukaryotic cells, the ubiquitin-proteasome system (UPS) plays a crucial role in selectively breaking down specific proteins. The ability of the UPS to target proteins effectively and expedite their removal has significantly contributed to the evolution of UPS-based targeted protein degradation (TPD) strategies. In particular, proteolysis targeting chimeras (PROTACs) are an immensely promising tool due to their high efficiency, extensive target range, and negligible drug resistance. This breakthrough has overcome the limitations posed by traditionally "non-druggable" proteins. However, their high molecular weight and constrained solubility impede the delivery of PROTACs. Fortunately, the field of nanomedicine has experienced significant growth, enabling the delivery of PROTACs through nanoscale drug-delivery systems, which effectively improves the stability, solubility, drug distribution, tissue-specific accumulation, and stimulus-responsive release of PROTACs. This article reviews the mechanism of action attributed to PROTACs and their potential implications for clinical applications. Moreover, we present strategies involving nanoplatforms for the effective delivery of PROTACs and evaluate recent advances in targeting nanoplatforms to the UPS. Ultimately, an assessment is conducted to determine the feasibility of utilizing PROTACs and nanoplatforms for UPS-based TPD. The primary aim of this review is to provide innovative, reliable solutions to overcome the current challenges obstructing the effective use of PROTACs in the management of cancer, neurodegenerative diseases, and metabolic syndrome. Therefore, this is a promising technology for improving the treatment status of major diseases.

Nano-PROTACs: state of the art and perspectives

PROteolysis TArgeting Chimeras (PROTACs), as a recently identified technique in the field of new drug development, provide new concepts for disease treatment and are expected to revolutionize drug discovery. With high specificity and flexibility, PROTACs serve as an innovative research tool to target and degrade disease-relevant proteins that are not currently pharmaceutically vulnerable to eliminating their functions by hijacking the ubiquitin-proteasome system. To date, PROTACs still face the challenges of low solubility, poor permeability, off-target effects, and metabolic instability. The combination of nanotechnology and PROTACs has been explored to enhance the in vivo performance of PROTACs regarding overcoming these challenging hurdles. In this review, we summarize the latest advancements in the building-block design of PROTAC prodrug nanoparticles and provide an overview of existing/potential delivery systems and loading approaches for PROTAC drugs. Furthermore, we discuss the current status and prospects of the split-and-mix approach for PROTAC drug optimization. Additionally, the advantages and translational potentials of carrier-free nano-PROTACs and their combinational therapeutic effects are highlighted. This review aims to foster a deeper understanding of this rapidly evolving field and facilitate the progress of nano-PROTACs that will continue to push the boundaries of achieving selectivity and controlled release of PROTAC drugs.

Chemoimmunotherapeutic Nanogel for Pre- and Postsurgical Treatment of Malignant Melanoma by Reprogramming Tumor-Associated Macrophages

Surgery is the primary method to treat malignant melanoma; however, the residual microtumors that cannot be resected completely often trigger tumor recurrence, causing tumor-related mortality following melanoma resection. Herein, we developed a feasible strategy based on the combinational chemoimmunotherapy by cross-linking carboxymethyl chitosan (CMCS)-originated polymetformin (PolyMetCMCS) with cystamine to prepare stimuli-responsive nanogel (PMNG) owing to the disulfide bond in cystamine that can be cleaved by the massive glutathione (GSH) in tumor sites. Then, chemotherapeutic agent doxorubicin (DOX) was loaded in PMNG, which was followed by a hyaluronic acid coating to improve the overall biocompatibility and targeting ability of the prepared nanogel (D@HPMNG). Notably, PMNG effectively reshaped the tumor immune microenvironment by reprogramming tumor-associated macrophage phenotypes and recruiting intratumoral CD8+ T cells owing to the inherited immunomodulatory capability of metformin. Consequently, D@HPMNG treatment remarkably suppressed melanoma growth and inhibited its recurrence after surgical resection, proposing a promising solution for overcoming lethal melanoma recurrence.

Cell Death Pathway Regulation by Functional Nanomedicines for Robust Antitumor Immunity

Cancer immunotherapy has become a mainstream cancer treatment over traditional therapeutic modes. Cancer cells can undergo programmed cell death including ferroptosis, pyroptosis, autophagy, necroptosis, apoptosis and cuproptosis which are find to have intrinsic relationships with host antitumor immune response. However, direct use of cell death inducers or regulators may bring about severe side effects that can also be rapidly excreted and degraded with low therapeutic efficacy. Nanomaterials are able to carry them for long circulation time, high tumor accumulation and controlled release to achieve satisfactory therapeutic effect. Nowadays, a large number of studies have focused on nanomedicines-based strategies through modulating cell death modalities to potentiate antitumor immunity. Herein, immune cell types and their function are first summarized, and state-of-the-art research progresses in nanomedicines mediated cell death pathways (e.g., ferroptosis, pyroptosis, autophagy, necroptosis, apoptosis and cuproptosis) with immune response provocation are highlighted. Subsequently, the conclusion and outlook of potential research focus are discussed.

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.

Cell Membrane-Camouflaged Nanoparticles Mediated Nucleic Acids Delivery

Nucleic acids have emerged as promising therapeutic agents for many diseases because of their potential in modulating gene expression. However, the delivery of nucleic acids remains a significant challenge in gene therapy. Although viral vectors have shown high transfection efficiency, concerns regarding teratogenicity or carcinogenicity have been raised. Non-viral vehicles, including cationic polymers, liposomes, and inorganic materials possess advantages in terms of safety, ease of preparation, and low cost. Nevertheless, they also face limitations related to immunogenicity, quick clearance in vivo, and lack of targeting specificity. On the other hand, bioinspired strategies have shown increasing potential in the field of drug delivery, yet there is a lack of comprehensive reviews summarizing the rapid development of bioinspired nanoparticles based on the cell membrane camouflage to construct the nucleic acids vehicles. Herein, we enumerated the current difficulties in nucleic acid delivery with various non-viral vehicles and provided an overview of bioinspired strategies for nucleic acid delivery.

Cooperatively designed aptamer-PROTACs for spatioselective degradation of nucleocytoplasmic shuttling protein for enhanced combinational therapy

Nucleocytoplasmic shuttling proteins (NSPs) have emerged as a promising class of therapeutic targets for many diseases. However, most NSPs-based therapies largely rely on small-molecule inhibitors with limited efficacy and off-target effects. Inspired by proteolysis targeting chimera (PROTAC) technology, we report a new archetype of PROTAC (PS-ApTCs) by introducing a phosphorothioate-modified aptamer to a CRBN ligand, realizing tumor-targeting and spatioselective degradation of NSPs with improved efficacy. Using nucleolin as a model, we demonstrate that PS-ApTCs is capable of effectively degrading nucleolin in the target cell membrane and cytoplasm but not in the nucleus, through the disruption of nucleocytoplasmic shuttling. Moreover, PS-ApTCs exhibits superior antiproliferation, pro-apoptotic, and cell cycle arrest potencies. Importantly, we demonstrate that a combination of PS-ApTCs-mediated nucleolin degradation with aptamer-drug conjugate-based chemotherapy enables a synergistic effect on tumor inhibition. Collectively, PS-ApTCs could expand the PROTAC toolbox to more targets in subcellular localization and accelerate the discovery of new combinational therapeutic approaches.

Delivering on Cell-Selective Protein Degradation Using Chemically Tailored PROTACs

PROTACs (Proteolysis-Targeting Chimeras) have emerged as a groundbreaking class of chemical tools that facilitate the degradation of target proteins by leveraging the ubiquitin-proteasome system (UPS). However, the effective utilization of PROTACs in chemical biology studies and therapeutics encounters significant challenges when it comes to achieving cell-selective protein degradation and in vivo applications. This review article aims to shed light on recent advancements in the development of Pro-PROTACs, which exhibit controlled protein degradation capabilities in response to external stimuli or disease-related endogenous biochemical signals. The article delves into the specific chemical strategies employed to regulate the interaction between PROTACs and E3 ubiquitin ligases or target proteins. These strategies enable spatial and temporal control over the protein degradation potential of Pro-PROTACs. Furthermore, the review summarizes recent investigations regarding the delivery of PROTACs using biodegradable nanoparticles for in vivo applications and targeted protein degradation. Such delivery systems hold great promise for enabling efficient and selective protein degradation in vivo. Lastly, the article provides a perspective on the future design of multifunctional PROTACs and their intracellular delivery mechanisms, with a particular focus on achieving cell-selective protein degradation.

Bioinspired PROTAC-induced macrophage fate determination alleviates atherosclerosis

Atherosclerosis is a major cause of death and disability in cardiovascular disease. Atherosclerosis associated with lipid accumulation and chronic inflammation leads to plaques formation in arterial walls and luminal stenosis in carotid arteries. Current approaches such as surgery or treatment with statins encounter big challenges in curing atherosclerosis plaque. The infiltration of proinflammatory M1 macrophages plays an essential role in the occurrence and development of atherosclerosis plaque. A recent study shows that TRIM24, an E3 ubiquitin ligase of a Trim family protein, acts as a valve to inhibit the polarization of anti-inflammatory M2 macrophages, and elimination of TRIM24 opens an avenue to achieve the M2 polarization. Proteolysis-targeting chimera (PROTAC) technology has emerged as a novel tool for the selective degradation of targeting proteins. But the low bioavailability and cell specificity of PROTAC reagents hinder their applications in treating atherosclerosis plaque. In this study we constructed a type of bioinspired PROTAC by coating the PROTAC degrader (dTRIM24)-loaded PLGA nanoparticles with M2 macrophage membrane (MELT) for atherosclerosis treatment. MELT was characterized by morphology, size, and stability. MELT displayed enhanced specificity to M1 macrophages as well as acidic-responsive release of dTRIM24. After intravenous administration, MELT showed significantly improved accumulation in atherosclerotic plaque of high fat and high cholesterol diet-fed atherosclerotic (ApoE-/-) mice through binding to M1 macrophages and inducing effective and precise TRIM24 degradation, thus resulting in the polarization of M2 macrophages, which led to great reduction of plaque formation. These results suggest that MELT can be considered a potential therapeutic agent for targeting atherosclerotic plaque and alleviating atherosclerosis progression, providing an effective strategy for targeted atherosclerosis therapy.

Visualization Tools for Detecting Microcystin-LR in the Biological System via Near-Infrared Fluorescent Probes

Numerous toxicological and epidemiological studies have shown that microcystin-LR (MC-LR) could cause a variety of toxicity to humans and animals. However, the absence of effective methods to trace MC-LR in biological systems has hindered the in-depth understanding of the mechanism of MC-LR toxicity. Near-infrared (NIR) fluorescent probes are crucial tools for accurate visualization and in-depth study of specific molecules in biological systems. Due to the lack of effective design strategies, NIR fluorescent probes for imaging MC-LR specifically in biological systems have not been reported yet. In order to address this pressing issue, herein, we have introduced a new and facile strategy to improve MC-LR detection and imaging in biological systems, and based on this design strategy, three NIR fluorescence probes (MC-RdTPA1, MC-RdTPA2, and MC-RdTPE1) have been constructed. These probes have several advantages: (i) have long emission wavelength and large Stokes shifts, which have great potential in vivo imaging applications; (ii) could selectively visualize MC-LR in cells; and (iii) showed stable fluorescence intensity in the pH range of 5.0-7.0. This work may provide a new avenue for the detection of MC-LR in biological systems and new tool to advance our knowledge of the mechanism of MC-LR toxicity.

Targeted Protein Degradation Technology and Nanomedicine: Powerful Allies against Cancer

Targeted protein degradation (TPD) is an emerging therapeutic strategy with the potential of targeting undruggable pathogenic proteins. After the first proof-of-concept proteolysis-targeting chimeric (PROTAC) molecule was reported, the TPD field has entered a new era. In addition to PROTAC, numerous novel TPD strategies have emerged to expand the degradation landscape. However, their physicochemical properties and uncontrolled off-target side effects have limited their therapeutic efficacy, raising concerns regarding TPD delivery system. The combination of TPD and nanotechnology offers great promise in improving safety and therapeutic efficacy. This review provides an overview of novel TPD technologies, discusses their clinical applications, and highlights the trends and perspectives in TPD nanomedicine.

Targeted therapy based on ubiquitin-specific proteases, signalling pathways and E3 ligases in non-small-cell lung cancer

Lung cancer is one of the most common malignant tumours worldwide, with the highest mortality rate. Approximately 1.6 million deaths owing to lung cancer are reported annually; of which, 85% of deaths occur owing to non-small-cell lung cancer (NSCLC). At present, the conventional treatment methods for NSCLC include radiotherapy, chemotherapy, targeted therapy and surgery. However, drug resistance and tumour invasion or metastasis often lead to treatment failure. The ubiquitin–proteasome pathway (UPP) plays an important role in the occurrence and development of tumours. Upregulation or inhibition of proteins or enzymes involved in UPP can promote or inhibit the occurrence and development of tumours, respectively. As regulators of UPP, ubiquitin-specific proteases (USPs) primarily inhibit the degradation of target proteins by proteasomes through deubiquitination and hence play a carcinogenic or anticancer role. This review focuses on the role of USPs in the occurrence and development of NSCLC and the potential of corresponding targeted drugs, PROTACs and small-molecule inhibitors in the treatment of NSCLC.

BRD4 Protein as a Target for Lung Cancer and Hematological Cancer Therapy: A Review

The BET protein family plays a crucial role in regulating the epigenetic landscape of the genome. Their role in regulating tumor-related gene expression and its impact on the survival of tumor cells is widely acknowledged. Among the BET family constituents, BRD4 is a significant protein. It is a bromodomain-containing protein located at the outer terminal that recognizes histones that have undergone acetylation. It is present in the promoter or enhancer region of the target gene and is responsible for initiating and sustaining the expression of genes associated with tumorigenesis. BRD4 expression is significantly elevated in various tumor types. Research has indicated that BRD4 plays a significant role in regulating various transcription factors and chromatin modification, as well as in repairing DNA damage and preserving telomere function, ultimately contributing to the survival of cancerous cells. The protein BRD4 has a significant impact on antitumor therapy, particularly in the management of lung cancer and hematological malignancies, and the promising potential of BRD4 inhibitors in the realm of cancer prevention and treatment is a topic of great interest. Therefore, BRD4 is considered a promising candidate for prophylaxis and therapy of neoplastic diseases. However, further research is required to fully comprehend the significance and indispensability of BRD4 in cancer and its potential as a therapeutic target.