Aptamer-LYTACs for Targeted Degradation of Extracellular and Membrane Proteins

Membrane-Bounded Intracellular E3 Ubiquitin Ligase-Targeting Chimeras (MembTACs) for Targeted Membrane Protein Degradation

Targeted protein degradation (TPD) represents a potent therapeutic strategy aimed at dismantling disease-associated target proteins. PROTAC is the most widely developed technique for intracellular protein degradation, while its degradation ability on membrane proteins has been hindered by the need for complex synthetic processes and limited permeability. In this study, we developed the membrane-bounded intracellular E3 ubiquitin ligase-targeting chimeras (MembTACs) that simultaneously recruit intracellular E3 ubiquitin ligase and bind to the desired membrane proteins for targeted degradation of membrane proteins. We demonstrate that the MembTACs can effectively utilize intracellular E3 ubiquitin ligase to degrade the therapeutically relevant membrane proteins of EpCAM and Met via the proteasome pathway. We anticipate that the new platform will expand the range of PROTAC applications and provide a new dimension for targeted membrane protein degradation.

Utilizing aptamers in targeted protein degradation strategies for disease therapy

Targeted protein degradation (TPD) has emerged as a promising therapeutic strategy, offering the potential to reduce disease-causing proteins that have traditionally been challenging to target using conventional small molecules. Despite significant advances made with TPD technologies, challenges such as high molecular weight, difficulties in identifying suitable ligands, suboptimal absorption, and metabolic instability remain unresolved. Recently, aptamers - single-stranded DNA or RNA oligonucleotides known for their high specificity and affinity for protein targets - have introduced novel opportunities to expand the scope of TPD, a strategy now referred to as aptamer-based TPD. This approach has demonstrated considerable promise in treating various diseases, such as cancer and ocular disorders. For example, an aptamer-proteolysis-targeting chimera (PROTAC) conjugate (APC) improved tumor targeting and reduced toxicity in a breast cancer model, and a vascular endothelial growth factor-degrading (VED)-lysosome-targeting chimera (LYTAC) molecule effectively inhibited abnormal vascular growth in vascular retinal diseases. These examples highlight the practical relevance and potential in advancing drug discovery efforts. In this review we provide a comprehensive overview of the latest advances in aptamer-based TPD strategies, including proteolysis-targeting and lysosome-targeting chimeras, emphasizing their applications, potential therapeutic benefits, as well as the challenges that must be overcome to fully harness their clinical potential. © 2025 The Pathological Society of Great Britain and Ireland.

Multivalent Aptamer Assembly Enhances Tumor-Specific Degradation of Transforming Growth Factor-Beta to Remodel the Stromal and Immunosuppressive Cancer Microenvironment

Extracellular proteins like transforming growth factor-β (TGFβ) are crucial enforcers in the development of cancer stroma and the tumor immunosuppressive microenvironment. Lysosome-targeting chimera-mediated protein degradation appeared as a promising tool for extracellular signal interference but was limited by several lysosome-trafficking receptors and inadequate in vivo degradation efficiency. Here, we designed a multivalent aptamer assembly with a universal pattern to drag extracellular proteins (e.g., TGFβ1) for lysosome degradation with high tumor specificity. By accelerating cell recognition-internalization and lysosomal delivery, the assembly promoted TGFβ blockade and degradation in pancreatic cancer cells and pancreatic stellate cells (PSCs). In vivo, the assembly exhibited highly tumor-specific accumulation and prolonged retention, which resulted in efficient TGFβ inhibition, stromal remodeling, and reversed polarization of immunosuppressive cells in the tumor microenvironment, as well as synergic therapeutic effects when combined with gemcitabine or ovalbumin. Therefore, this study provides a feasible strategy to construct a multivalent aptamer assembly for tumor-specific extracellular protein degradation, after remodeling the tumor stromal and immunosuppressive microenvironment in a manner that enhances the effects of cancer chemotherapy and immunotherapy.

Structure-Guided Development of Chemically Tailored Peptide Binders of RNF43/ZNRF3 to Enable Versatile Design of Membrane Protein-Targeting PROTACs

Targeted membrane protein degradation using cell surface E3 ligases RNF43/ZNRF3 via proteolysis targeting chimeras (PROTACs) represents an effective strategy for treating membrane drug targets that cannot be fully inhibited using traditional inhibitors. Several ingenious chimeras have been developed to tether RNF43/ZNRF3 to target membrane proteins, resulting in the degradation of targets at sub-nanomolar concentrations both in vitro and in vivo. However, currently available RNF43/ZNRF3 binders are genetically encoded and have poor plasticity, which limits the design and promotion of such PROTACs. Here, we exploited the AlphaFold-predicted complex structures of ligand-bound RNF43/ZNRF3 and developed a class of chemically tailored peptide binders for ZNRF3/RNF43. With these peptide binders that can be conveniently prepared by de novo peptide synthesis, we established a new membrane protein degradation platform that allows versatile modular design and targeted degradation of clinically relevant membrane proteins, i.e., PD-L1 and EGFR. This study presents a new subtype within the PROTAC field to develop therapeutic peptides targeting membrane proteins.

Targeted degradation of extracellular proteins: state of the art and diversity of degrader designs

Selective elimination of proteins associated with the pathogenesis of diseases is an emerging therapeutic modality with distinct advantages over traditional inhibitor-based approaches. This strategy, called targeted protein degradation (TPD), is based on hijacking the cellular proteolytic machinery using chimeric degrader molecules that physically link the target protein of interest with the degradation effectors. The TPD era began with the development of PROteolysis TAtrgeting Chimeras (PROTACs) in 2001, with various methods and applications currently available. Classical PROTAC molecules are heterobifunctional chimeras linking target proteins with E3 ubiquitin ligases. This induced interaction leads to the ubiquitylation of the target protein, which is needed for its recognition and subsequent degradation by the cellular proteasomes. However, this technology is limited to intracellular proteins since the effectors involved (E3 ubiquitin ligases and proteasomes) are located in the cytosol. The related methods for selective destruction of proteins present in the extracellular space have only emerged recently and are collectively termed extracellular TPD (eTPD). The prototypic eTPD technology utilizes LYsosomal TArgeting Chimeras (LYTACs) that link extracellular target proteins (secreted or membrane-associated) to lysosome-targeting receptors (LTRs) on the cell surface. The resulting complex is then internalized by endocytosis and trafficked to lysosomes, where the target protein is degraded. The successful elimination of various extracellular proteins via LYTACs and related approaches has been reported, including several important targets in oncology that drive tumor growth and dissemination. This review summarizes current progress in the eTPD field and focuses primarily on the respective technological developments. It discusses the design principles and diversity of degrader molecules and the landscape of available targets and effectors that can be employed for eTPD. Finally, it emphasizes current open questions, challenges, and perspectives of this technological platform to promote the expansion of the eTPD toolkit and further development of its therapeutic applications.

Sortilin-Mediated Rapid, Precise and Sustained Degradation of Membrane Proteins via mRNA-Encoded Lysosome-Targeting Chimera

Recent advances in lysosome-targeting degradation technologies have introduced strategies to regulate therapeutic membrane proteins (MPs), potentially transforming treatment paradigms. However, challenges persist, including limited degradation precision due to the broad distribution of lysosome-targeting receptors (LTRs), as well as the high cost and complexity of recombinant protein production or chemical synthesis. Herein, it identifies sortilin as a promising LTR, highly expressed in malignancies but minimally present in healthy tissues outside the nervous system. Using AlphaFold-Multimer, it screened for a specific non-endogenous protein binder to sortilin and developed a modular, mRNA-encoded lysosomal targeting chimera (MedTAC) strategy, enabling rapid design and precise degradation of oncogenic MPs. In a breast cancer-bearing mouse model, a single low dose of MedTACPTK7 (0.5 mg kg-1) reduced protein tyrosine kinase-7 (PTK7) levels by up to 80% within 24 h, with sustained degradation of 44% at 72 h, demonstrating excellent pharmacokinetics. MedTACPTK7 significantly extended survival to over 50 days without systemic toxicity, compared to 20-30 days in controls. This MedTAC strategy establishes sortilin as a selective and efficient shuttle for targeted protein degradation, offering a scalable, rapidly producible platform for biochemical research and precise therapeutic applications.

DNA Framework-Based Lysosome-Targeting Chimeras: Intracellular ATP-Facilitated Extracellular Protein Degradation

Targeted protein degradation (TPD) offered a riveting therapeutic paradigm to eradicate pathogenesis-relevant proteins, especially those belonging to the once-considered undruggable proteome. Considering that adenosine triphosphate (ATP) is the primary energy source for cell activities and lysosomes are important ATP storage sites, herein, the first example of dual-function tetrahedral DNA framework-based lysosome-targeting chimeras (TDF-LYTACs) is proposed for elucidating the correlation between extracellular protein degradation via the lysosome pathway and the fluctuations in intracellular ATP levels. In our study, platelet-derived growth factor (PDGF), a driver of cancer invasion and metastasis, was chosen as the protein of interest. To achieve multifunctionality, we employed a tetrahedral DNA framework formed by an aptamer of PDGF, human apurinic/apyrimidinic endonuclease 1 (APE1)-triggered ATP probes, and a ligand of the cell-surface lysosome-shuttling receptor (IGFIIR). TDF-LYTACs efficiently and quickly shuttled PDGF proteins to lysosomes, degraded them through the lysosomal pathway, and further visualized the intracellular ATP level synchronously. Furthermore, we found a significant correlation between the degradation efficiency of PDGF and intracellular ATP levels over time; that is, a higher ATP level corresponded to higher degradation efficiency and vice versa. We anticipate that our versatile TDF-LYTACs will offer a perspective for degrading multifunctional extracellular proteins.

Engineering Covalent Aptamer Chimeras for Enhanced Autophagic Degradation of Membrane Proteins

Targeted degradation of membrane proteins represents an attractive strategy for eliminating pathogenesis-related proteins. Aptamer-based chimeras hold great promise as membrane protein degraders, however, their degradation efficacy is often hindered by the limited structural stability and the risk of off-target effects due to the non-covalent interaction with target proteins. We here report the first design of a covalent aptamer-based autophagosome-tethering chimera (CApTEC) for the enhanced autophagic degradation of cell-surface proteins, including transferrin receptor 1 (TfR1) and nucleolin (NCL). This strategy relies on the site-specific incorporation of sulfonyl fluoride groups onto aptamers to enable the cross-linking with target proteins, coupled with the conjugation of an LC3 ligand to hijack the autophagy-lysosomal pathway for targeted protein degradation. The chemically engineered CApTECs exhibit enhanced on-target retention and improved structural stability. Our results also demonstrate that CApTECs achieve remarkably enhanced and prolonged degradation of membrane proteins compared to the non-covalent designs. Furthermore, the CApTEC targeting TfR1 is combined with 5-fluorouracil (5-FU) for synergistic tumor therapy in a mouse model, leading to substantial suppression of tumor growth. Our strategy may provide deep insights into the LC3-mdiated autophagic degradation, affording a modular and effective strategy for membrane protein degradation and precise therapeutic applications.

Trivalent siRNA-Conjugates with Guanosine as ASGPR-Binder Show Potent Knock-Down In Vivo

To increase the chemical space around the well-known GalNAc-ligand as ASGPR-binder, a high-throughput screening campaign was performed, testing approximately 550,000 compounds. After evaluation of the potential screening hits, only one compound, which showed high similarity with guanosine nucleosides, was chosen for further profiling. Crystal structure analysis revealed the coordination of the Ca2+-ion within the ASGPR-binding site by the cis-diol motif of the ribose unit as well as an additional π-π-interaction of the purine heterocycle to tryptophan-243. Based on these findings, guanosine was attached via the 5'-OH group to a recently described morpholino-based nucleotide using two different linker units. The resulting morpholino-guanosine building blocks were conjugated to the 5'-end of a literature-known transthyretin targeting small interfering RNA (siRNA), leading to trivalent siRNA-guanosine conjugates, which were tested for their TTR knockdown and exhibited similar potencies as the analogous GalNAc-conjugates in vitro and in vivo.

Identification of a non-inhibitory aptameric ligand to CRL2ZYG11B E3 ligase for targeted protein degradation

As a crucial element of proteolysis targeting chimeras (PROTACs), the choice of E3 ubiquitin ligase significantly influences degradation efficacy and selectivity. However, the available arsenal of E3 ligases for PROTAC development remains underexplored, severely limiting the scope of targeted protein degradation. In this study, we identify a non-inhibitory aptamer targeting ZYG11B, a substrate receptor of the Cullin 2-RING ligase complex, as an E3 warhead for targeted protein degradation. This aptamer-based PROTAC platform, termed ZATAC, is facilely produced through bioorthogonal chemistry or self-assembly and shows promise in eliminating several undruggable target proteins, including nucleolin (NCL), SRY-box transcription factor 2 (SOX2), and mutant p53-R175H, underscoring its universality and versatility. To specifically deliver ZATACs into cancer cells, we further develop DNA three-way junction-based ZATACs (3WJ-ZATACs) by integrating an additional aptamer that selectively recognizes the protein overexpressed on the surface of cancer cells. The 3WJ-ZATACs demonstrate in vivo tumor-specific distribution and achieve dual-target degradation, thereby suppressing tumor growth without causing noticeable toxicity. In summary, ZATACs represent a general, modular, and straightforward platform for targeted protein degradation, offering insights into the potential of other untapped E3 ligases.

A Bifunctional Lysosome-Targeting Chimera Nanoplatform for Tumor-Selective Protein Degradation and Enhanced Cancer Immunotherapy

Lysosome-targeting chimeras (LYTACs) have recently emerged as a promising therapeutic strategy for degrading extracellular and membrane-associated pathogenic proteins by hijacking lysosome-targeting receptors. However, the antitumor performance of LYTAC is limited by its insufficient tumor accumulation and nonspecific activation. Additionally, the synergistic effects of LYTACs and other therapeutic modalities are crucial. To address these issues, a bifunctional LYTAC nanoplatform (NLTC) is developed for tumor-selective protein degradation and enhanced cancer immunotherapy. By rationally controlling the surface composition, the NLTC can effectively transport extracellular or membrane proteins into lysosomes for degradation via cation-independent mannose 6-phosphate receptors. With removable surface modification, an NLTC is obtained that efficiently accumulated in tumor tissues and avoided on-target off-tumor toxicity. Moreover, the synthesis method of NLTC is generally applicable to various enzymes. Thus, catalase (CAT) is encapsulated with NLTC to synergistically degrade cancer cell surface programmed death ligand-1 (PD-L1), relieve the immunosuppressive tumor microenvironment for effective cancer immunotherapy, and significantly inhibit tumor growth, recurrence, and metastasis in B16F10-bearing mice. This work presents a bifunctional LYTAC nanoplatform that can not only perform tissue-selective protein degradation but also integrate other therapeutic modalities, providing insights into the design of advanced LYTAC technologies for clinical applications.

Protein-Based Degraders: From Chemical Biology Tools to Neo-Therapeutics

The nascent field of targeted protein degradation (TPD) could revolutionize biomedicine due to the ability of degrader molecules to selectively modulate disease-relevant proteins. A key limitation to the broad application of TPD is its dependence on small-molecule ligands to target proteins of interest. This leaves unstructured proteins or those lacking defined cavities for small-molecule binding out of the scope of many TPD technologies. The use of proteins, peptides, and nucleic acids (otherwise known as "biologics") as the protein-targeting moieties in degraders addresses this limitation. In the following sections, we provide a comprehensive and critical review of studies that have used proteins and peptides to mediate the degradation and hence the functional control of otherwise challenging disease-relevant protein targets. We describe existing platforms for protein/peptide-based ligand identification and the drug delivery systems that might be exploited for the delivery of biologic-based degraders. Throughout the Review, we underscore the successes, challenges, and opportunities of using protein-based degraders as chemical biology tools to spur discoveries, elucidate mechanisms, and act as a new therapeutic modality.

Emerging Trends in DNA Nanotechnology-Enabled Cell Surface Engineering

Cell surface engineering is a rapidly advancing field, pivotal for understanding cellular physiology and driving innovations in biomedical applications. In this regard, DNA nanotechnology offers unprecedented potential for precisely manipulating and functionalizing cell surfaces by virtue of its inherent programmability and versatile functionalities. Herein, this Perspective provides a comprehensive overview of emerging trends in DNA nanotechnology for cell surface engineering, focusing on key DNA nanostructure-based tools, their roles in regulating cellular physiological processes, and their biomedical applications. We first discuss the strategies for integrating DNA molecules onto cell surfaces, including the attachment of oligonucleotides and the higher-order DNA nanostructure. Second, we summarize the impact of DNA-based surface engineering on various cellular processes, such as membrane protein degradation, signaling transduction, intercellular communication, and the construction of artificial cell membrane components. Third, we highlight the biomedical applications of DNA-engineered cell surfaces, including targeted therapies for cancer and inflammation, as well as applications in cell capture/protection and diagnostic detection. Finally, we address the challenges and future directions in DNA nanotechnology-based cell surface engineering. This Perspective aims to provide valuable insights for the rational design of DNA nanotechnology in cell surface engineering, contributing to the development of precise and personalized medicine.

Hepatocyte targeting via the asialoglycoprotein receptor

This review highlights the potential of asialoglycoprotein receptor (ASGPR)-mediated targeting in advancing liver-specific treatments and underscores the ongoing progress in the field. First, we provide a comprehensive examination of the nature of ASGPR ligands, both natural and synthetic. Next, we explore various drug delivery strategies leveraging ASGPR, with a particular emphasis on the delivery of therapeutic nucleic acids such as small interfering RNAs (siRNAs) and antisense oligonucleotides (ASOs). An in-depth analysis of the current status of RNA interference (RNAi) and ASO-based therapeutics is included, detailing approved therapies and those in various stages of clinical development (phases 1 to 3). Afterwards, we give an overview of other ASGPR-targeted conjugates, such as those with peptide nucleic acids or aptamers. Finally, targeted protein degradation of extracellular proteins through ASGPR is briefly discussed.

Nucleic Acid Covalent Tags

The selective and site-specific chemical labeling of proteins has emerged as a pivotal research area in chemical biology and cell biology. An effective protein labeling typically meets several criteria, including high specificity, rapid and robust conjugation under physiological conditions, operation at low concentrations with biocompatibility, and minimal perturbation of the protein function and activity. The conjugation of nucleic acids with proteins has garnered significant attention recently due to the rapid advancements in nucleic acid probe technologies, leveraging the programmable nature of nucleic acids alongside the multifaceted functionalities of proteins. It helps to convert protein-specific information into nucleic acid signals, facilitating upstream versatile recognition and downstream signal amplification for the target protein. This review critically evaluates the recent progress in nucleic acid-based protein labeling methodologies, with a specific focus on covalent labeling using aptamer tags, protein fusion tags or the technique of metabolic oligosaccharide engineering. The tags establish covalent linkages with target proteins through various modalities such as small molecules or metabolic glycan engineering. The insights presented in the review highlight promising avenues for the development of highly specific and versatile protein labeling techniques, which is essential for the improvement of protein-targeted detection and imaging across diverse biological contexts.

PROTACs coupled with oligonucleotides to tackle the undruggable

Undruggable targets account for roughly 85% of human disease-related targets and represent a category of therapeutic targets that are difficult to tackle with traditional methods, but their considerable clinical importance. These targets are generally defined by planar functional interfaces and the absence of efficient ligand-binding pockets, making them unattainable for conventional pharmaceutical strategies. The advent of oligonucleotide-based proteolysis-targeting chimeras (PROTACs) has instilled renewed optimism in addressing these challenges. These PROTACs facilitate the targeted degradation of undruggable entities, including transcription factors (TFs) and RNA-binding proteins (RBPs), via proteasome-dependent mechanisms, thereby presenting novel therapeutic approaches for diseases linked to these targets. This review offers an in-depth examination of recent progress in the integration of PROTAC technology with oligonucleotides to target traditionally undruggable proteins, emphasizing the design principles and mechanisms of action of these innovative PROTACs.

The Emergence of Oligonucleotide Building Blocks in the Multispecific Proximity-Inducing Drug Toolbox of Destruction

Oligonucleotides are a rapidly emerging class of therapeutics. Their most well-known examples are informational drugs that modify gene expression by binding mRNA. Despite inducing proximity between biological machinery and mRNA when applied to modulating gene expression, oligonucleotides are not typically labeled as "proximity-inducing" in literature. Yet, they have recently been explored as building blocks for multispecific proximity-inducing drugs (MPIDs). MPIDs are unique because they can direct endogenous biological machinery to destroy targeted molecules and cells, in contrast to traditional drugs that inhibit only their functions. The unique mechanism of action of MPIDs has enabled the targeting of previously "undruggable" molecular entities that cannot be effectively inhibited. However, the development of MPIDs must ensure that these molecules will selectively direct a potent, destruction-based mechanism of action toward intended targets over healthy tissues to avoid causing life-threatening toxicities. Oligonucleotides have emerged as promising building blocks for the design of MPIDs because they are sequence-controlled molecules that can be rationally designed to program multispecific binding interactions. In this Review, we examine the emergence of oligonucleotide-containing MPIDs in the proximity induction space, which has been dominated by antibody and small molecule MPID modalities. Moreover, examples of oligonucleotides developed as MPID candidates in immunotherapy and protein degradation are discussed to demonstrate the utility of oligonucleotides in expanding the scope and selectivity of the MPID toolbox. Finally, we discuss the utility of programming "AND" gates into oligonucleotide scaffolds to encode conditional responses that have the potential to be incorporated into MPIDs, which can further enhance their selectivity, thus increasing the scope of this drug category.

Specifically Editing Cancer Sialoglycans for Enhanced In Vivo Immunotherapy through Aptamer-Enzyme Chimeras

Immune checkpoint blockade (ICB) therapies have demonstrated remarkable clinical success in treating cancer. However, their objective response rate remains suboptimal because current therapies rely on limited immune checkpoints that fail to cover the multiple immune evasion pathways of cancer. To explore potential ICB strategies, we propose a glycoimmune checkpoint elimination (glycoICE) therapy based on targeted editing of sialoglycans on the tumor cell surface using an aptamer-enzyme chimera (ApEC). The ApEC can be readily generated via a one-step bioorthogonal procedure, allowing for large-scale and uniform production. It specifically targets and desialylates cancer cells, disrupting the sialoglycan-Siglec axis to activate immune cells and enhance immunotherapy efficacy, while its high tumor selectivity minimizes side effects from indiscriminate desialylation of normal tissues. Furthermore, the ApEC has the potential to be a versatile platform for specific editing of sialoglycans in different tumor models by adjusting the aptamer sequences to target specific protein markers. This research not only introduces a novel molecular tool for the effective editing of sialoglycans in complex environments, but also provides valuable insights for advancing DNA-based drugs towards in vivo and clinical applications.

Chemically engineered antibodies for autophagy-based receptor degradation

Cell surface receptor-targeted protein degraders hold promise for drug discovery. However, their application is restricted because of the complexity of creating bifunctional degraders and the reliance on specific lysosome-shuttling receptors or E3 ubiquitin ligases. To address these limitations, we developed an autophagy-based plasma membrane protein degradation platform, which we term AUTABs (autophagy-inducing antibodies). Through covalent conjugation with polyethylenimine (PEI), the engineered antibodies acquire the capacity to degrade target receptors through autophagy. The degradation activities of AUTABs are self-sufficient, without necessitating the participation of lysosome-shuttling receptors or E3 ubiquitin ligases. The broad applicability of this platform was then illustrated by targeting various clinically important receptors. Notably, combining specific primary antibodies with a PEI-tagged secondary nanobody also demonstrated effective degradation of target receptors. Thus, our study outlines a strategy for directing plasma membrane proteins for autophagic degradation, which possesses desirable attributes such as ease of generation, independence from cell type and broad applicability.

Aptamer-based Immune Checkpoint Inhibition for Cancer Immunotherapy

Cancer has long been a significant threat to human life and health. The advent of immune checkpoint blockade strategies has reversed cancer-induced immune suppression, advanced the development of immunotherapy, and offered new hope in the fight against cancer. Aptamers, which possess the same specificity and affinity as antibodies, are advantageous due to their synthetic accessibility and ease of modification, providing novel insights for immune checkpoint research. In this review, we outline the key aptamers currently developed for immune checkpoints such as CTLA-4, PD-1, PD-L1 and Siglec-15. We explore their potential in therapeutic strategies, including functionalizing or engineering aptamers for covalent binding, valency control, and nanostructure assembly, as well as investigating molecular mechanisms such as glycosylated protein functions and cell-cell interactions. Finally, the future applications of aptamers in immunotherapy are discussed.

Controllable multivalent LYTACs enhance targeted protein degradation

We present a versatile DNA-based LYTAC framework that allows control over the valency of chimeras and the distance between ligands through DNA self-assembly. By evaluating the degradation capabilities of LYTACs with 1, 3, and 9 valences, we confirm the broad applicability of the multivalent enhancement effect across different lysosome-targeting receptor-mediated degradation pathways. Our findings provide valuable insights into improving the degradation efficiency of LYTACs.

Molecular Programming Design of Glyconucleic Acid Aptamer with High Stability

Functional nucleic acids (FNAs), possessing specific biological functions beyond their informational roles, have gained widespread attention in disease therapeutics. However, their clinical application is severely limited by their low serum stability in complex physiological environments. In this work, a precise molecular programming strategy is explored to prepare glyconucleic acid aptamers (GNAAs) with high serum stability. Four glyconucleic acid modules compatible with commercial solid-phase synthesis are designed and synthesized. Through precise molecular design, the accurate modification of four different carbohydrate ligands at specific sites of DNA aptamers is achieved. It is demonstrated that glycosylation modification can significantly increase DNA aptamers' serum stability while maintaining their structures and high affinity. The stabilization effect is superior to that of currently commonly used commercial chemical modifications. Moreover, it is confirmed that this approach displays insignificant effects on the DNA aptamers' tumor-targeting ability and metabolism in vivo. This method offers a simple, economical, and efficient strategy for precise glycosylation modification of nucleic acids. This allows to prepare glycosyl functional nucleic acids with high serum stability, which can expand the application scope of functional nucleic acids and promote the practical transformation of functional nucleic acids.

Targeted degradation of membrane and extracellular proteins with LYTACs

Targeted protein degradation technology has gained substantial momentum over the past two decades as a revolutionary strategy for eliminating pathogenic proteins that are otherwise refractory to treatment. Among the various approaches developed to harness the body's innate protein homeostasis mechanisms for this purpose, lysosome targeting chimeras (LYTACs) that exploit the lysosomal degradation pathway by coupling the target proteins with lysosome-trafficking receptors represent the latest innovation. These chimeras are uniquely tailored to degrade proteins that are membrane-bound and extracellular, encompassing approximately 40% of all proteome. Several novel LYTAC formulas have been developed recently, providing valuable insights for the design and development of therapeutic degraders. This review delineates the recent progresses of LYTAC technology, its practical applications, and the factors that dictate target degradation efficiency. The potential and emerging trends of this technology are discussed as well. LYTAC technology offers a promising avenue for targeted protein degradation, potentially revolutionizing the therapeutic landscape for numerous diseases.

Aptamer and N-Degron Ensemble (AptaGron) as a Target Protein Degradation Strategy

Target protein degradation (TPD) is a promising strategy for catalytic downregulation of target proteins through various cellular proteolytic pathways. Despite numerous reports on novel TPD mechanisms, the discovery of target-specific ligands remains a major challenge. Unlike small-molecule ligands, aptamers offer significant advantages, owing to their SELEX-based systematic screening method. To fully utilize aptamers for TPD, we designed an aptamer and N-degron ensemble system (AptaGron) that circumvents the need for synthetic conjugations between aptamers and proteolysis-recruiting units. In our AptaGron system, a peptide nucleic acid containing an N-degron peptide and a sequence complementary to the aptamer was designed. Using this system, we successfully degraded three target proteins, tau, nucleolin, and eukaryotic initiation factor 4E (eIF4E), which lack specific small-molecule ligands. Our results highlight the potential of the AptaGron approach as a robust platform for targeted protein degradation.

Nanomotor-Driven Targeting Chimeras as Accelerators for the Degradation of Extracellular Proteins

Targeted protein degradation (TPD) is emerging as a therapeutic paradigm and a serviceable research tool in chemical biology and disease treatment. However, without driving sources, most targeting chimeras (TACs) lack the capability of self-diffusion and active searching in biological environments, which significantly impedes degradation efficiency. Herein, nanomotor-driven targeting chimeras (MotorTACs) are ingeniously designed to achieve effective internalization and degradation of extracellular platelet-derived growth factor (PDGF), a driver to cancer invasion and metastasis. Catalyzed by endogenous H2O2, MotorTACs diffused rapidly and searched actively in living cells, as visualized at the single-particle level under the dark-field mode. Hydrolysis efficiency is significantly enhanced as target protein degradation is complete in only 4 h. Furthermore, MotorTACs-mediated degradation of PDGF is found to be via the lysosome and ubiquitin-proteasome dual-degradation pathways. Taking advantage of the properties, it is anticipated that MotorTACs provide a unique strategy against extracellular undruggable proteins, thus advancing the development of therapeutic interventions in chemical biology and disease treatment.

DNA Nanotechnology for Application in Targeted Protein Degradation

DNA is a kind of flexible and versatile biomaterial for constructing nanostructures and nanodevices. Due to high biocompatibility and programmability and easy modification and fabrication, DNA nanotechnology has emerged as a powerful tool for application in intracellular targeted protein degradation. In this review, we summarize the recent advances in the design and mechanism of targeted protein degradation technologies such as protein hydrolysis targeted chimeras, lysosomal targeted chimeras, and autophagy based protein degradation. Subsequently, we introduce the DNA nanotechnologies of DNA cascade circuits, DNA nanostructures, and dynamic machines. Moreover, we present the latest developments in DNA nanotechnologies in targeted protein degradation. Finally, the vision and challenges are discussed.

Lysosome Targeted Nanoparticle Aggregation Reverses Immunosuppressive Tumor Microenvironment for Cancer Immunotherapy

Nanotechnology has proven its enormous application value in clinical practice. However, current research on nanomedicines mainly focuses on developing nanoparticles as delivery carriers to maximize the bioavailability of therapeutic agents, with little attention on exploring their potential to directly regulate physiological processes. In this study, inspired by the lysosomal swelling caused by excessive accumulation of undegraded substances, this work presents a lysosomal-targeting aggregated nanoparticle (LTANP) for cancer treatment. By rationally engineering surface composition, properties, and interparticle interactions, LTANP achieves efficient tumor accumulation and selective targeted aggregation in lysosomes of cancer cells, leading to unrelievable lysosomal swelling, and ultimately inducing lysosomal membrane permeabilization (LMP) of cancer cells. Further analysis shows that nanoparticle aggregation-mediated LMP can effectively trigger immunogenic cell death (ICD) by impairing autophagy-lysosome pathway, evoking robust antitumor immune responses and reversing tumor immunogenicity from "cold" to "hot" in a melanoma model. Additionally, LTANP can combine with clinically approved programmed death ligand-1 (PD-L1) antibodies to further unleash T cell-mediated antitumor immunity, significantly enhancing antitumor performance, inhibiting tumor recurrence and metastasis. This work demonstrates the potential of rationally engineered nanostructures in directly combating cancer and provides novel insights for the development of advanced nanoparticle-based cancer treatment.

Nanotechnology-Enabled Targeted Protein Degradation for Cancer Therapeutics

Targeted protein degradation (TPD) represents an innovative therapeutic strategy that has garnered considerable attention from both academic and industrial sectors due to its promising developmental prospects. Approximately 85% of human proteins are implicated in disease pathogenesis, and the FDA has approved around 400 drugs targeting these disease-related proteins, predominantly enzymes, transcription factors, and non-enzymatic proteins. However, existing therapeutic modalities fail to address certain "high-value" targets, such as c-Myc and Ras. The emergence of proteolysis-targeting chimeras (PROTAC) technology has introduced TPD into a new realm. The capability to target non-druggable sites has expanded the therapeutic horizon of protein-based drugs, although challenges related to bioavailability, safety, and adverse side effects have constrained their clinical progression. Nano-delivery systems and emerging TPD modalities, such as molecular glues, lysosome-targeted chimeras (LYTACs), autophagy system compounds (ATTEC), and antibody PROTAC (AbTACs), have mitigated some of these limitations. This paper reviews the latest advancements in TPD, highlighting their applications and benefits in cancer therapy, and concludes with a forward-looking perspective on the future development of this field.

Flower-Shaped PCR Scaffold-Based Lateral Flow Bioassay for Bacillus cereus Endospores Detection

Bacillus cereus, a foodborne pathogen, produces resilient endospores that are challenging to detect with conventional methods. This study presents a novel Flower-Shaped PCR Scaffold-based Lateral Flow Biosensor (FSPCRS-LFB), which employs an aptamer-integrated PCR scaffold as capture probes, replacing the traditional streptavidin-biotin (SA-Bio) approach. The FSPCRS-LFB demonstrates high sensitivity and cost-efficiency in detecting B. cereus endospores, with a limit of detection (LOD) of 4.57 endospores/mL a visual LOD of 102 endospores/mL, and a LOD of 6.78 CFU/mL for endospore-cell mixtures. In chicken and tea samples, the platform achieved LODs of 74.5 and 52.8 endospores/mL, respectively, with recovery rates of 82.19% to 97.88%. Compared to existing methods, the FSPCRS-LFB offers a 3.7-fold increase in sensitivity while reducing costs by 26% over the SA-Bio strategy and 87.5% over rolling circle amplification (RCA). This biosensor provides a rapid, sensitive and cost-effective solution for point-of-care testing (POCT) of B. cereus endospores, expanding detection capabilities and offering novel approaches for pathogen detection.

Lysosome-targeting chimeras containing an endocytic signaling motif trigger endocytosis and lysosomal degradation of cell-surface proteins

Lysosome-targeting degradation technologies have emerged as a promising therapeutic strategy for the selective depletion of target extracellular and cell-surface proteins by harnessing a cell-surface effector protein such as lysosome-targeting receptors (LTRs) or transmembrane E3 ligases that direct lysosomal degradation. We recently developed a lysosome-targeting degradation platform termed signal-mediated lysosome-targeting chimeras (SignalTACs) that functions independently of an LTR or E3 ligase; these are engineered fusion proteins comprising a target binder, a cell-penetrating peptide (CPP), and a lysosomal sorting signal motif (P1). Herein, we present the next-generation SignalTACs containing a single endocytic signal that bypasses the need for a CPP. We demonstrate that the fusion with a 10-amino acid endocytic signaling peptide (P3) derived from the cation-independent mannose-6-phosphate receptor (CI-M6PR) induces robust internalization and lysosomal degradation of the target protein. The P3-based SignalTAC exhibited enhanced antitumor efficacy compared to the parent antibody. We envision that the fusion of the endocytic signaling peptide P3 to a target binder may allow the construction of an effective degrader for membrane-associated targets. Furthermore, mechanistic studies identified different drivers for the activities of the P3- and P1-based SignalTACs, which is expected to provide crucial insights toward the harnessing of the intrinsic signaling pathways to direct protein trafficking and degradation.

Cascade Enzymes Confined in DNA Nanoanchors for Antitumor Therapy

Cascade-enzyme reaction systems have emerged as promising tools for treating malignant tumors by efficiently converting nutrients into toxic substances. However, the challenges of poor localized retention capacity and utilization of highly active enzymes often result in extratumoral toxicity and reduced therapeutic efficacy. In this study, we introduced a cell membrane-DNA nanoanchor (DNANA) with a spatially confined cascade enzyme for in vivo tumor therapy. The DNANAs are constructed using a polyvalent cholesterol-labeled DNA triangular prism, ensuring high stability in cell membrane attachment. Glucose oxidase (GOx) and horseradish peroxidase (HRP), both modified with streptavidin, are precisely confined to biotin-labeled DNANAs. Upon intratumoral injection, DNANA enzymes efficiently colonize the tumor site through cellular membrane engineering strategies, significantly reducing off-target enzyme leakage and the associated risks of extratumoral toxicity. Furthermore, DNANA enzymes demonstrated effective cancer therapy in vitro and in vivo by depleting glucose and producing highly cytotoxic hydroxyl radicals in the vicinity of tumor cells. This membrane-engineered cascade-enzyme reaction system presents a conceptual approach to tumor treatment.

Programming DNA Nanoassemblies into Polyvalent Lysosomal Degraders for Potent Degradation of Pathogenic Membrane Proteins

Lysosome-targeting chimera (LYTAC) shows great promise for protein-based therapeutics by targeted degradation of disease-associated membrane or extracellular proteins, yet its efficiency is constrained by the limited binding affinity between LYTAC reagents and designated proteins. Here, we established a programmable and multivalent LYTAC system by tandem assembly of DNA into a high-affinity protein degrader, a heterodimer aptamer nanostructure targeting both pathogenic membrane protein and lysosome-targeting receptor (insulin-like growth factor 2 receptor, IGF2R) with adjustable spatial distribution or organization pattern. The DNA-based multivalent LYTACs showed enhanced efficacy in removing immune-checkpoint protein programmable death-ligand 1 (PD-L1) and vascular endothelial growth factor receptor 2 (VEGFR2) in tumor cell membrane that respectively motivated a significant increase in T cell activity and a potent effect on cancer cell growth inhibition. With high programmability and versatility, this multivalent LYTAC system holds considerable promise for realizing protein therapeutics with enhanced activity.

A plug-and-play monofunctional platform for targeted degradation of extracellular proteins and vesicles

Existing strategies use bifunctional chimaeras to mediate extracellular protein degradation. However, these strategies rely on specific lysosome-trafficking receptors to facilitate lysosomal delivery, which may raise resistance concerns due to intrinsic cell-to-cell variation in receptor expression and mutations or downregulation of the receptors. Another challenge is establishing a universal platform applicable in multiple scenarios. Here, we develop MONOTAB (MOdified NanOparticle with TArgeting Binders), a plug-and-play monofunctional degradation platform that can drag extracellular targets into lysosomes for degradation. MONOTAB harnesses the inherent lysosome-targeting ability of certain nanoparticles to obviate specific receptor dependency and the hook effect. To achieve high modularity and programmable target specificity, we utilize the streptavidin-biotin interaction to immobilize antibodies or other targeting molecules on nanoparticles, through an antibody mounting approach or by direct binding. Our study reveals that MONOTAB can induce efficient degradation of diverse therapeutic targets, including membrane proteins, secreted proteins, and even extracellular vesicles.

Inhibitors to degraders: Changing paradigm in drug discovery

The chemical understanding of biological processes provides not only a deeper insight but also a solution to abnormal biological functioning. Protein degradation, a natural biological process for debris removal in the cell, has been studied for years. The recent finding that natural degradation pathways can be utilized for therapeutic purposes is a paradigm shift in the drug discovery approach. Methods such as Proteolysis Targeting Chimera (PROTAC), lysosomal targeting chimera, hydrophobic tagging, AUtophagy TArgeting Chimera, AUTOphagy TArgeting Chimera and several other variants of these methods have made a considerable impact on the way of drug design. Few selected examples testify that a huge wave of change is on the way. The drug design based on the targeted protein degradation is a powerful tool in our arsenal. More molecules will be invented that will uncover the hidden secrets of biological functioning and provide enduring solutions to several unmet medical needs.

Multivalent Aptamer-Based Lysosome-Targeting Chimeras (LYTACs) Platform for Mono- or Dual-Targeted Proteins Degradation on Cell Surface

Selective protein degradation platforms have opened novel avenues in therapeutic development and biological inquiry. Antibody-based lysosome-targeting chimeras (LYTACs) have emerged as a promising technology that extends the scope of targeted protein degradation to extracellular targets. Aptamers offer an advantageous alternative owing to their potential for modification and manipulation toward a multivalent state. In this study, a chemically engineered platform of multivalent aptamer-based LYTACs (AptLYTACs) is established for the targeted degradation of either single or dual protein targets. Leveraging the biotin-streptavidin system as a molecular scaffold, this investigation reveals that trivalently mono-targeted AptLYTACs demonstrate optimum efficiency in degrading membrane proteins. The development of this multivalent AptLYTACs platform provides a principle of concept for mono-/dual-targets degradation, expanding the possibilities of targeted protein degradation.

Cell Membrane as A Promising Therapeutic Target: From Materials Design to Biomedical Applications

The cell membrane is a crucial component of cells, protecting their integrity and stability while facilitating signal transduction and information exchange. Therefore, disrupting its structure or impairing its functions can potentially cause irreversible cell damage. Presently, the tumor cell membrane is recognized as a promising therapeutic target for various treatment methods. Given the extensive research focused on cell membranes, it is both necessary and timely to discuss these developments, from materials design to specific biomedical applications. This review covers treatments based on functional materials targeting the cell membrane, ranging from well-known membrane-anchoring photodynamic therapy to recent lysosome-targeting chimaeras for protein degradation. The diverse therapeutic mechanisms are introduced in the following sections: membrane-anchoring phototherapy, self-assembly on the membrane, in situ biosynthesis on the membrane, and degradation of cell membrane proteins by chimeras. In each section, we outline the conceptual design or general structure derived from numerous studies, emphasizing representative examples to understand advancements and draw inspiration. Finally, we discuss some challenges and future directions in membrane-targeted therapy from our perspective. This review aims to engage multidisciplinary readers and encourage researchers in related fields to advance the fundamental theories and practical applications of membrane-targeting therapeutic agents.

Targeted protein degradation directly engaging lysosomes or proteasomes

Targeted protein degradation (TPD) has been established as a viable alternative to attenuate the function of a specific protein of interest in both biological and clinical contexts. The unique TPD mode-of-action has allowed previously undruggable proteins to become feasible targets, expanding the landscape of "druggable" properties and "privileged" target proteins. As TPD continues to evolve, a range of innovative strategies, which do not depend on recruiting E3 ubiquitin ligases as in proteolysis-targeting chimeras (PROTACs), have emerged. Here, we present an overview of direct lysosome- and proteasome-engaging modalities and discuss their perspectives, advantages, and limitations. We outline the chemical composition, biochemical activity, and pharmaceutical characteristics of each degrader. These alternative TPD approaches not only complement the first generation of PROTACs for intracellular protein degradation but also offer unique strategies for targeting pathologic proteins located on the cell membrane and in the extracellular space.

Extracellular targeted protein degradation: an emerging modality for drug discovery

Targeted protein degradation (TPD) has emerged in the past decade as a major new drug modality to remove intracellular proteins with bispecific small molecules that recruit the protein of interest (POI) to an E3 ligase for degradation in the proteasome. Unlike classic occupancy-based drugs, intracellular TPD (iTPD) eliminates the target and works catalytically, and so can be more effective and sustained, with lower dose requirements. Recently, this approach has been expanded to the extracellular proteome, including both secreted and membrane proteins. Extracellular targeted protein degradation (eTPD) uses bispecific antibodies, conjugates or small molecules to degrade extracellular POIs by trafficking them to the lysosome for degradation. Here, we focus on recent advances in eTPD, covering degrader systems, targets, molecular designs and parameters to advance them. Now almost any protein, intracellular or extracellular, is addressable in principle with TPD.

Insulin-like Growth Factor 2-Tagged Aptamer Chimeras (ITACs) Modular Assembly for Targeted and Efficient Degradation of Two Membrane Proteins

Overexpression of pathogenic membrane proteins drives abnormal proliferation and invasion of tumor cells. Various strategies to durably knockdown membrane proteins with heterobifunctional degraders have been successfully developed, including LYTAC, KineTAC, and AbTAC. However, challenges including complicated synthetic procedures and the inability to simultaneously degrade multiple pathogenic proteins still exist. Herein, we developed insulin-like growth factor 2 (IGF2)-tagged aptamer chimeras (ITACs) that link the cell-surface lysosome-targeting receptor IGF2R and membrane proteins of interest (POIs) based on specific recognition of aptamers to the POIs and high-affinity binding of IGF2 to IGF2R. We demonstrated that ITACs exhibit robust degradation efficiency of various membrane proteins in multiple cell lines. Furthermore, systematic studies revealed that a moderate cell-surface IGF2R level is responsible for the excellent degradation performance of ITACs. Importantly, we further established a modular assembly strategy that allows assembly of one IGF2 with two aptamers with precise stoichiometry (dITACs), enabling cooperative and simultaneous degradation of two membrane proteins. This work provides an efficient and facile target membrane protein degradation platform and will shed light on the treatment of diseases related to the overexpression of membrane proteins.

Aptamer-Based Smart Targeting and Spatial Trigger-Response Drug-Delivery Systems for Anticancer Therapy

In recent years, the field of drug delivery has witnessed remarkable progress, driven by the quest for more effective and precise therapeutic interventions. Among the myriad strategies employed, the integration of aptamers as targeting moieties and stimuli-responsive systems has emerged as a promising avenue, particularly in the context of anticancer therapy. This review explores cutting-edge advancements in targeted drug-delivery systems, focusing on the integration of aptamers and stimuli-responsive platforms for enhanced spatial anticancer therapy. In the aptamer-based drug-delivery systems, we delve into the versatile applications of aptamers, examining their conjugation with gold, silica, and carbon materials. The synergistic interplay between aptamers and these materials is discussed, emphasizing their potential in achieving precise and targeted drug delivery. Additionally, we explore stimuli-responsive drug-delivery systems with an emphasis on spatial anticancer therapy. Tumor microenvironment-responsive nanoparticles are elucidated, and their capacity to exploit the dynamic conditions within cancerous tissues for controlled drug release is detailed. External stimuli-responsive strategies, including ultrasound-mediated, photo-responsive, and magnetic-guided drug-delivery systems, are examined for their role in achieving synergistic anticancer effects. This review integrates diverse approaches in the quest for precision medicine, showcasing the potential of aptamers and stimuli-responsive systems to revolutionize drug-delivery strategies for enhanced anticancer therapy.

Conjugation with glucagon like peptide-1 enables targeted protein degradation

Lysosome-targeting chimeras (LYTACs) have emerged as a promising technique to extend the scope of targeted protein degradation to extracellular proteins, e.g., secreted proteins and membrane-anchored proteins. However, up to now, only a small number of lysosomal targeting receptors (LTRs), such as cation-independent mannose 6-phosphate receptor (CI-M6PR) and asialoglycoprotein receptor (ASGPR), were reported to build LYTACs for degradation of extracellular proteins. Therefore, it is important to explore more functionalized ligands for the relevant LTRs to expand the LYTAC framework. Herein, we demonstrate a new LTR ligand-glucagon like peptide 1 (GLP-1) based targeted degradation platform, termed GLP-1 receptor-targeting chimeras (GLP-1-LYTAC). GLP-1-LYTACs are formed by conjugating GLP-1 with targeted binder (such as antibody) through Click Chemistry, showing efficiently lysosomal degradation of both extracellular proteins (GFP and Neutravidin) as well as cell membrane proteins (EGFR and PD-L1). We believe that this novel GLP-1-LYTAC will open up a new dimension for targeted protein breakdown.

IGF2 Peptide-Based LYTACs for Targeted Degradation of Extracellular and Transmembrane Proteins

Lysosome-targeting chimeras (LYTACs) have recently been developed to facilitate the lysosomal degradation of specific extracellular and transmembrane molecular targets. However, the LYTAC particles described to date are based on glycopeptide conjugates, which are difficult to prepare and produce on a large scale. Here, we report on the development of pure protein LYTACs based on the non-glycosylated IGF2 peptides, which can be readily produced in virtually any facility capable of monoclonal antibody production. These chimeras utilize the IGF2R/CI-M6PR pathway for lysosomal shuttling and, in our illustrative example, target programmed death ligand 1 (PD-L1), eliciting physiological effects analogous to immune checkpoint blockade. Results from in vitro assays significantly exceed the effects of anti-PD-L1 antibodies alone.

Insulin-like Growth Factor 2 (IGF2)-Fused Lysosomal Targeting Chimeras for Degradation of Extracellular and Membrane Proteins

Targeted degradation of the cell-surface and extracellular proteins via the endogenous lysosomal degradation pathways, such as lysosome-targeting chimeras (LYTACs), has recently emerged as an attractive tool to expand the scope of extracellular chemical biology. Herein, we report a series of recombinant proteins genetically fused to insulin-like growth factor 2 (IGF2), which we termed iLYTACs, that can be conveniently obtained in high yield by standard cloning and bacterial expression in a matter of days. We showed that both type-I iLYTACs, in which IGF2 was fused to a suitable affibody or nanobody capable of binding to a specific protein target, and type-II iLYTAC (or IGF2-Z), in which IGF2 was fused to the IgG-binding Z domain that served as a universal antibody-binding adaptor, could be used for effective lysosomal targeting and degradation of various extracellular and membrane-bound proteins-of-interest. These heterobifunctional iLYTACs are fully genetically encoded and can be produced on a large scale from conventional E. coli expression systems without any form of chemical modification. In the current study, we showed that iLYTACs successfully facilitated the cell uptake, lysosomal localization, and efficient lysosomal degradation of various disease-relevant protein targets from different mammalian cell lines, including EGFR, PD-L1, CD20, and α-synuclein. The antitumor properties of iLYTACs were further validated in a mouse xenograft model. Overall, iLYTACs represent a general and modular strategy for convenient and selective targeted protein degradation, thus expanding the potential applications of current LYTACs and related techniques.

Covalent LYTAC Enabled by DNA Aptamers for Immune Checkpoint Degradation Therapy

Immune checkpoint blockade (ICB) therapy, while achieving tremendous clinical successes, still suffers from a low objective response rate in clinical cancer treatment. As a proof-of-concept study, we propose a new immune checkpoint degradation (ICD) therapy relying on lysosome-targeting chimera (LYTAC) to deplete immune checkpoint programmed death ligand-1 (PD-L1) on the tumor cell surface. Our designed chimeric aptamer on one side targets lysosome-trafficking receptor, and on the other side allows biorthogonal covalent-conjugation-reinforced specific binding of PD-L1. This covalent LYTAC is able to hijack PD-L1 for lysosomal degradation with greatly improved efficiency over its noncovalent counterpart in complex in vivo environment. Beyond abolishing the PD-1/PD-L1 axis associated immune resistance, we demonstrate for the first time that LYTAC-triggered PD-L1 degradation could directly cause immunogenic apoptosis of tumor cells to elicit tumor-specific immune responses, offering unparalleled advantages over ICB antibody therapy. Remarkably, ICD therapy with covalent LYTAC achieves comparable or higher antitumor efficacy while causing significantly less inflammatory injury compared to antibody-based ICB therapy. Moreover, covalent LYTAC can serve as a general platform for specifically degrading other membrane-associated proteins, making it a promising tool for future applications. Our work presents a novel molecular tool for effective LYTAC in complex environments, offering valuable insights in pushing DNA-based LYTAC drugs toward in vivo and clinical applications.

Selective Proteolysis of Activated Transcriptional Factor by NIR-Responsive Palindromic DNA Thalidomide Conjugate Inhibits the Canonical Smad Pathway

Dysfunctional transcription factors that activate abnormal expressions of specific proteins are often associated with the progression of various diseases. Despite being attractive drug targets, the lack of druggable sites has dramatically hindered their drug development. The emergence of proteolysis targeting chimeras (PROTACs) has revitalized the drug development of many conventional hard-to-drug protein targets. Here, the use of a palindromic double-strand DNA thalidomide conjugate (PASTE) to selectively bind and induce proteolysis of targeted activated transcription factor (PROTAF) is reported. The selective proteolysis of the dimerized phosphorylated receptor-regulated Smad2/3 and inhibition of the canonical Smad pathway validates PASTE-mediated PROTAF. Further aptamer-guided active delivery of PASTE and near-infrared light-triggered PROTAF are demonstrated. Great potential in using PASTE for the selective degradation of the activated transcription factor is seen, providing a powerful tool for studying signaling pathways and developing precision medicines.

Chemical Tailoring of Aptamer Glues with Significantly Enhanced Recognition Ability for Targeted Membrane Protein Degradation

Cell membrane proteins play a crucial role in the development of early cancer diagnosis strategies and precision medicine techniques. However, the application of aptamers in cell membrane protein-based biomedical research is limited by their inherent drawbacks, such as sensitivity to the recognition environment and susceptibility to enzymatic degradation, which leads to the loss of recognition ability. To address these challenges, this study presents a subzero-temperature-enabled molecule stacking strategy for the on-demand tailoring of aptamer glues for the precision recognition and efficient degradation of membrane protein. Mechanistic studies revealed that nucleic acid molecule stacking occurred during the freezing and melting processes, facilitating a rapid click reaction by bringing two reactive groups together. In vitro investigations demonstrated that the strategy confers aptamer glues with significantly enhanced specific recognition ability and binding affinity, allowing the distinction of a targeted cell line from a nontargeted cell line. Moreover, the engineered aptamer glue exhibited impressive targeted cell membrane protein degradation ability; around 74% of the c-Met protein was degraded in 24 h. These findings hold great potential for advancing cancer diagnosis and targeted therapy through the development of more stable and reliable aptamer probes.

Tools and techniques for the discovery of therapeutic aptamers: recent advances

INTRODUCTION

The pursuit of novel therapeutic agents for serious diseases such as cancer has been a global endeavor. Aptamers characteristic of high affinity, programmability, low immunogenicity, and rapid permeability hold great promise for the treatment of diseases. Yet obtaining the approval for therapeutic aptamers remains challenging. Consequently, researchers are increasingly devoted to exploring innovative strategies and technologies to advance the development of these therapeutic aptamers.

AREAS COVERED

The authors provide a comprehensive summary of the recent progress of the SELEX (Systematic Evolution of Ligands by EXponential enrichment) technique, and how the integration of modern tools has facilitated the identification of therapeutic aptamers. Additionally, the engineering of aptamers to enhance their functional attributes, such as inhibiting and targeting, is discussed, demonstrating the potential to broaden their scope of utility.

EXPERT OPINION

The grand potential of aptamers and the insufficient development of relevant drugs have spurred countless efforts for stimulating their discovery and application in the therapeutic field. While SELEX techniques have undergone significant developments with the aid of advanced analysis instruments and ingeniously updated aptameric engineering strategies, several challenges still impede their clinical translation. A key challenge lies in the insufficient understanding of binding conformation and susceptibility to degradation under physiological conditions. Despite the hurdles, our opinion is optimistic. With continued progress in overcoming these obstacles, the widespread utilization of aptamers for clinical therapy is envisioned to become a reality soon.