Active-targeting long-acting protein-glycopolymer conjugates for selective cancer therapy

All-in-one multifunctional tri-block glycopolymers for targeted delivery of cisplatin and cancer chemotherapy

Cisplatin (CDDP) as a first-line chemotherapy drug has long suffered drawbacks of severe side effects and poor pharmacokinetics. Thus, various nano-carriers of complex architectures and multi-step modifications have been developed to overcome these challenges, but a simple delivery system with integrated multi-functions is still in demand. Herein, we synthesized a new type of glyco-based triple hydrophilic block copolymers for the delivery of CDDP and thereof cancer therapy. The incorporated glucuronic acid part is complexed with CDDP with high entrapment efficiency, while providing pH-responsive release in the acidic tumor microenvironment. The galactose segment is implanted for liver-targeting effect, which can also significantly lower the side effects of CDDP. As a result, the CDDP-loaded nanoparticle PGG2/Pt showed selectively faster endocytosis rates into HepG2 cells in vitro, with the calculated IC50 value even comparable to that of free CDDP. The in vivo experiments on a HepG2-bearing mouse model, PGG2/Pt showed excellent anti-tumor activity and enhanced drug accumulation on tumor, together with much lowered nephrotoxicity, hepatotoxicity, and splenic toxicity. This work provides a new strategy for CDDP delivery with higher loading efficiency as well as biosafety.

Synthetic Glycopolymers in Tumor Immunotherapy

Glycopolymers, as an emerging immunomodulatory material, exhibit considerable promise in the field of tumor immunotherapy. Compared to native saccharides, they offer significant advantages, including enhanced immune activity, controllable structure and sequence, elevated stability, and high purity. By mimicking the multivalency of native sugar chains, glycopolymers significantly enhance their interactions with receptors, a phenomenon known as the "glycocluster effect." Glycopolymers are capable of modulating immune cell functions, inhibiting tumor immune evasion, and reconfiguring the tumor microenvironment. This review provides a comprehensive overview of recent advancements in the application of glycopolymers, protein-glycopolymer conjugates, glycopolymer-based micro/nanoparticles, and glycopolymer-engineered cells in tumor immunotherapy. These glycopolymer-based materials enhance antitumor immune responses by specifically interacting with immune cell surface receptors, significantly improving the precision and efficacy of immunotherapy, and providing valuable insights for the development of innovative therapeutic strategies in cancer treatment.

Thiol-selective native grafting from polymerization for the generation of protein-polymer conjugates

Protein-polymer conjugates combine properties of biopolymers and synthetic polymers, such as specific bioactivity and increased stability, with great benefits for various applications from catalysis to biomedicine. Furthermore, polymer conjugation can mimic important posttranslational modifications of proteins such as glycosylation. There are typically two approaches to create protein-polymer conjugates: the protein is functionalized in advance with an initiator for a grafting-from method or a previously produced polymer is conjugated to the protein via a grafting-to method. In this study, we present a new approach that uses native proteins and allows for direct grafting-from using a thiol-induced, light-activated controlled radical polymerization (TIRP) that is initiated at thiols from specific cysteine residues of the protein. This straightforward method is employed to introduce polymers onto proteins and enzymes without any prior protein modifications, it works in aqueous buffer and maintains the protein's native structure and activity. The resulting protein-polymer conjugates exhibit high molar masses and low dispersities. We demonstrate the versatility of this approach by introducing different types of polymers such as hydrophilic poly(2-hydroxyethyl acrylate) (pHEAA), temperature-responsive poly(N-isopropylacrylamide) (pNIPAM) as well as glycopolymers mimicking the natural protein glycosylation and enabling selective interactions. We present successful combinations of the protein and polymer functions e.g., temperature-induced aggregation leading to an increase in enzyme activity and the introduction of artificial glycosylation inducing specific protein-protein cluster formation and giving straightforward access to glycosurfaces. Based on this straightforward, potentially scalable yet highly controlled synthesis of protein-polymer conjugates, various areas of applications are envisioned ranging from biomedicine to material sciences.

Lysosome Targeting Chimaeras for Glut1-Facilitated Targeted Protein Degradation

Targeted protein degradation technology holds great potential in biomedicine, particularly in treating tumors and other protein-related diseases. Research on intracellular protein degradation using molecular glues and PROTAC technology is leading, while research on the degradation of membrane proteins and extracellular proteins through the lysosomal pathway is still in the preclinical stage. The scarcity of useful targets is an immense limitation to technological advancement, making it essential to explore novel, potentially effective approaches for targeted lysosomal degradation. Here, we employed the glucose transporter Glut1 as an innovative lysosome-targeting receptor and devised the Glut1-Facilitated Lysosomal Degradation (GFLD) strategy. We synthesized potential Glut1 ligands via reversible addition-fragmentation chain transfer (RAFT) polymerization and acquired antibody-glycooligomer conjugates through bioorthogonal reactions as lysosome-targeting protein degradation molecules, utilized in the management of PD-L1 high-expressing triple-negative breast cancer. The glucose transporter Glut1 as a lysosome-targeting receptor exhibits potential for the advancement of a broader array of medications in the future.

Biomaterial-Based Responsive Nanomedicines for Targeting Solid Tumor Microenvironments

Solid tumors are composed of a highly complex and heterogenic microenvironment, with increasing metabolic status. This environment plays a crucial role in the clinical therapeutic outcome of conventional treatments and innovative antitumor nanomedicines. Scientists have devoted great efforts to conquering the challenges of the tumor microenvironment (TME), in respect of effective drug accumulation and activity at the tumor site. The main focus is to overcome the obstacles of abnormal vasculature, dense stroma, extracellular matrix, hypoxia, and pH gradient acidosis. In this endeavor, nanomedicines that are targeting distinct features of TME have flourished; these aim to increase site specificity and achieve deep tumor penetration. Recently, research efforts have focused on the immune reprograming of TME in order to promote suppression of cancer stem cells and prevention of metastasis. Thereby, several nanomedicine therapeutics which have shown promise in preclinical studies have entered clinical trials or are already in clinical practice. Various novel strategies were employed in preclinical studies and clinical trials. Among them, nanomedicines based on biomaterials show great promise in improving the therapeutic efficacy, reducing side effects, and promoting synergistic activity for TME responsive targeting. In this review, we focused on the targeting mechanisms of nanomedicines in response to the microenvironment of solid tumors. We describe responsive nanomedicines which take advantage of biomaterials' properties to exploit the features of TME or overcome the obstacles posed by TME. The development of such systems has significantly advanced the application of biomaterials in combinational therapies and in immunotherapies for improved anticancer effectiveness.

Glycopolymer-grafted nanoparticles as glycosaminoglycan mimics with cell proliferation and anti-tumor metastasis activities

Glycosaminoglycans (GAGs) are naturally existing extracellular components with a variety important biological functions. However, their heterogeneous chemical compositions and the challenges in purification have become the main disadvantages for clinical applications. Thus, various synthetic glycopolymers have been designed to mimic the structures and functions of natural GAGs. In the current study, glycopolymers from structurally simple glucose or N-acetylglucosamine monomers were synthesized, which were further subjected to sulfation of different degrees and grafting onto silica nanoparticles, leading to spherical-shaped nano-structures of uniform diameters. With the successively strengthened multivalent effect, the obtained glycopolymer nanoparticles not only showed excellent effects on promotion of cell proliferation by stabilizing growth factors, but also significantly inhibited tumor metastasis by weakening the adhesion between tumor cells and activated platelets. Among the prepared nanoparticles, S3-PGNAc@Si with N-acetylglucosamine segment and the highest sulfation degree exhibited the strongest bioactivities, which were even close to those of heparin. This work presents a novel approach for structural and functional mimicking of natural GAGs from simple and low-cost monosaccharides, holding great potential for a range of biomedical applications.

The role of protein corona on nanodrugs for organ-targeting and its prospects of application

Nowadays, nanodrugs become a hotspot in the high-end medical field. They have the ability to deliver drugs to reach their destination more effectively due to their unique properties and flexible functionalization. However, the fate of nanodrugs in vivo is not the same as those presented in vitro, which indeed influenced their therapeutic efficacy in vivo. When entering the biological organism, nanodrugs will first come into contact with biological fluids and then be covered by some biomacromolecules, especially proteins. The proteins adsorbed on the surface of nanodrugs are known as protein corona (PC), which causes the loss of prospective organ-targeting abilities. Fortunately, the reasonable utilization of PC may determine the organ-targeting efficiency of systemically administered nanodrugs based on the diverse expression of receptors on cells in different organs. In addition, the nanodrugs for local administration targeting diverse lesion sites will also form unique PC, which plays an important role in the therapeutic effect of nanodrugs. This article introduced the formation of PC on the surface of nanodrugs and summarized the recent studies about the roles of diversified proteins adsorbed on nanodrugs and relevant protein for organ-targeting receptor through different administration pathways, which may deepen our understanding of the role that PC played on organ-targeting and improve the therapeutic efficacy of nanodrugs to promote their clinical translation.