Daejin Kim

Gold Nanoparticles Displaying Tumor‐Associated Self‐Antigens as a Potential Vaccine for Cancer Immunotherapy

Golden vaccine for cancers. Gold nanoparticles enable efficient antigen delivery to dendritic cells and then activate the cells to facilitate cross-presentation, inducing antigen-specific cytotoxic T-lymphocyte responses for effective cancer therapy.

Synthesis and therapeutic evaluation of an aptide-docetaxel conjugate targeting tumor-associated fibronectin

Targeted delivery of anticancer drugs to tumors has attracted considerable research interest because of its potential to reduce adverse toxicity while improving therapeutic efficacy. In this study, we synthesized and evaluated the therapeutic efficacy of a conjugate of a high-affinity peptide (aptide) and the anticancer drug docetaxel (DTX). A fibronectin extra domain B (EDB)-specific aptide (APTEDB) was used as a cancer-specific targeting ligand. An APTEDB-DTX conjugate was synthesized from an alkyne-modified aptide and azide-modified DTX via click chemistry. A microscopy study revealed selective binding of dye-labeled APTEDB to EDB-overexpressing cancer cells. The cytotoxicity of the conjugate toward EDB-overexpressing murine lung carcinoma (LLC) and human glioblastoma (U87MG) was similar to that of free DTX. In a pharmacokinetic study, APTEDB-DTX formulated with PEG400/ethanol(5%) exhibited a circulation half-life similar to that of a Tween-80/ethanol formulation of parent DTX. Finally, an evaluation of intravenously injected APTEDB-DTX in mice bearing EDB-positive tumors showed that APTEDB-DTX inhibited the growth of both LLC allograft and U87MG xenograft tumors with an efficacy better than the parent-DTX formulation but with much lower toxicity, as evidenced by reduced body weight loss. Taken together, these results indicate that the aptide-drug conjugate system described here may hold potential as a targeted therapy regimen.

Bioengineered yeast-derived vacuoles with enhanced tissue-penetrating ability for targeted cancer therapy

Significance Tumor tissues have formidable physiological barriers, such as a high interstitial pressure and a densely entangled ECM. Most synthetic nanomaterials used for drug delivery fail to penetrate tumor tissues deeply and localize only in perivascular areas, thereby limiting their therapeutic efficacy. This report describes bioengineered yeast-derived natural nanocarriers for cancer-specific targeting and drug delivery. Budding yeast was genetically engineered to produce large numbers of nanosized compartments—vacuoles that display cancer—targeting ligands on their surface. The nanosized vacuoles significantly enhanced drug penetration in tumor xenografts, and consequently prevented tumor growth without eliciting immune responses. This result shows that the biological nanocarriers overcome the limitations associated with synthetic cancer-targeting nanomaterials, and thus can be used to treat various cancers. Despite the appreciable success of synthetic nanomaterials for targeted cancer therapy in preclinical studies, technical challenges involving their large-scale, cost-effective production and intrinsic toxicity associated with the materials, as well as their inability to penetrate tumor tissues deeply, limit their clinical translation. Here, we describe biologically derived nanocarriers developed from a bioengineered yeast strain that may overcome such impediments. The budding yeast Saccharomyces cerevisiae was genetically engineered to produce nanosized vacuoles displaying human epidermal growth factor receptor 2 (HER2)-specific affibody for active targeting. These nanosized vacuoles efficiently loaded the anticancer drug doxorubicin (Dox) and were effectively endocytosed by cultured cancer cells. Their cancer-targeting ability, along with their unique endomembrane compositions, significantly enhanced drug penetration in multicellular cultures and improved drug distribution in a tumor xenograft. Furthermore, Dox-loaded vacuoles successfully prevented tumor growth without eliciting any prolonged immune responses. The current study provides a platform technology for generating cancer-specific, tissue-penetrating, safe, and scalable biological nanoparticles for targeted cancer therapy.

Intracellular Delivery of Bioactive Cargos to Hard-to-Transfect Cells Using Carbon Nanosyringe Arrays under an Applied Centrifugal g-Force.

There is considerable interest in developing a common, universal platform for delivering biomacromolecules such as proteins and RNAs into diverse cells with high efficiency. Here, it is shown that carbon nanosyringe arrays (CNSAs) under an applied centrifugal g-force (cf-CNSAs) can deliver diverse bioactive cargos directly into the cytosol of hard-to-transfect cells with relatively high efficiency and reproducibility. The cf-CNSA platform, an optimized version of a previous CNSA-mediated intracellular delivery platform that adds a g-force feature, exhibits more rapid and superior delivery of cargos to various hard-to-transfect cells than is the case in the absence of g-force. Active species, including small interfering RNAs, plasmids, and proteins are successfully transported across plasma membrane barriers into various cells. By overcoming the limitations of currently available transfection methods, the cf-CNSA platform paves the way to universal delivery of a variety of cargos, facilitating the analysis of cellular responses in diverse cell types.

Conversion of Low‐Affinity Peptides to High‐Affinity Peptide Binders by Using a β‐Hairpin Scaffold‐Assisted Approach

Affinity maturation of protein‐targeting peptides is generally accomplished by homo‐ or heterodimerization of known peptides. However, applying a heterodimerization approach is difficult because it is not clear a priori what length or type of linker is required for cooperative binding to a target. Thus, an efficient and simple affinity maturation method for converting low‐affinity peptides into high‐affinity peptides would clearly be advantageous for advancing peptide‐based therapeutics. Here, we describe the development of a novel affinity maturation method based on a robust β‐hairpin scaffold and combinatorial phage‐display technology. With this strategy, we were able to increase the affinity of existing peptides by more than four orders of magnitude. Taken together, our data demonstrate that this scaffold‐assisted approach is highly efficient and effective in generating high‐affinity peptides from their low‐affinity counterparts.

Preparation and therapeutic evaluation of paclitaxel-conjugated low-molecular-weight chitosan nanoparticles

Synthetic and natural polymers have been widely utilized as raw materials for manufacturing drug-delivery vehicles to treat diseases. This widespread use reflects several favorable features of these polymers, including facile chemical modification, ease of creating nano-sized particles through a self-assembly process, the ability to solubilize or encapsulate hydrophobic drugs within the core, and enhanced accumulation in tumors by the so-called enhance permeability and retention (EPR) effect. Among such polymeric materials, natural polymers such as dextran, chitosan, and hyaluronic acid may have advantages over synthetic polymers in the preparation of nanoparticle (NP)-based drug delivery systems in terms of biocompatibility. Because such natural polysaccharide components are water-soluble, their polymers require modification with hydrophobic components before NP formation via a self-assembly process. It has been shown that hydrophobically modified dextran, hyaluronic acid, and high-molecular-weight chitosan self-assemble into NPs that exhibit effective anticancer efficacy through EPR effectmediated, passive tumor targeting. In fact, chitosan has been widely used in the pharmaceutical field because it is known to be biocompatible and biodegradable, and increases the solubility of hydrophobic drugs. Very recently, we utilized water-soluble, low-molecular-weight chitosan (LMWC) as a carrier to achieve oral delivery of anticancer drugs, such as paclitaxel (PTX) and docetaxel, and anti-diabetic peptide drugs, such as insulin and exendin-4. All conjugates between LMWC and drugs of interest in our previous studies showed high oral bioavailability with little toxicity, suggesting the potential of LMWC as a biocompatible carrier for drug-delivery applications. In the present study, we prepared conjugates between LMWC and PTX with different drug content and evaluated the therapeutic efficacy of self-assembled NPs formed from these conjugates (Figure 1(a)).

Spinning-induced Rhabdomyolysis: Eleven Case Reports and Review of the Literature

Non-traumatic exertional rhabdomyolysis (exRML) occurs in individuals with normal muscles when the energy supplied to the muscle is insufficient. Here, we report 11 cases of spinning-induced rhabdomyolysis and review related literature. Spinning is a kind of indoor bicycle sport. The 11 patients who were diagnosed with exRML and admitted to CHA Bundang Medical Center were female and their ages ranged from 15 to 46 years. Two to three days prior to the presentation, the patients had attended a spinning class for the first time. All the patients had been otherwise healthy without any known medical illnesses. They were successfully treated without any complications, except mild non-symptomatic hypocalcemia. However, in the literature, severe complications such as compartment syndrome or acute kidney injury had been reported in relation to exRML including spinning-induced rhabdomyolysis. This spinning exercise needs prior guidelines and specific warnings to prevent exertional rhabdomyolysis.

Targeted cancer therapy using a fusion protein of TNFα and a tumor-associated fibronectin-specific aptide

Tumor necrosis factor-α has shown potent antitumor effects in preclinical and clinical studies. However, severe side effects at less than therapeutic doses have limited its systemic delivery, prompting the need for a new strategy for targeted delivery of the protein to tumors. Here, we report a fusion protein of mouse tumor necrosis factor (TNF)-α (mTNFα) and a cancer-targeting, high-affinity aptide and investigate its therapeutic efficacy in tumor-bearing mice. A fusion protein consisting of mTNFα, a linker, and an aptide specific to extra domain B (EDB) of fibronectin (APTEDB), designated mTNFα-APTEDB, was successfully produced by expression in Escherichia coli. mTNFα-APTEDB retained specificity and affinity for its target, EDB. In mice bearing EDB-overexpressing fibrosarcomas, mTNFα-APTEDB showed greater efficacy in inhibiting tumor growth than mTNFα alone or mTNFα linked to a nonrelevant aptide, without causing an appreciable loss in body weight. Moreover, in vivo antitumor efficacy was further significantly increased by combination treatment with the chemotherapeutic drug, melphalan, suggesting a synergistic effect attributable to enhanced drug uptake into the tumor as a result of TNFα-mediated enhanced vascular permeability. These results suggest that a fusion protein of mTNFα with a cancer-targeting peptide could be a new anticancer therapeutic option for ensuring potent antitumor efficacy after systemic delivery.

An approach for half-life extension and activity preservation of an anti-diabetic peptide drug based on genetic fusion with an albumin-binding aptide

Abstract Although the peptide, exenatide, has been widely used as a drug for the treatment of type 2 diabetes, its short plasma half‐life requires frequent subcutaneous injection, resulting in poor patient compliance in addition to side effects such as infection at the sites of injection. Here, we report a novel long‐acting fusion peptide comprising exenatide and a human serum albumin (HSA)‐binding aptide. A phage display screen of a library of aptides, yielded an HSA‐specific aptide (APTHSA) that bound HSA with a Kd of 188 nM. The recombinant fusion peptide comprising exenatide and APTHSA (exenatide‐APTHSA) was expressed in Escherichia coli and purified by affinity and size‐exclusion chromatography. The resulting exenatide‐APTHSA fusion peptide showed glucose‐induced insulin secretion activity similar to that of native exenatide when tested in vitro using the INS‐1 cell line. A pharmacokinetic analysis of exenatide‐APTHSA after subcutaneous administration revealed a 4‐fold longer plasma half‐life (1.3 vs. 0.35 h) compared with exenatide. Furthermore, exenatide‐APTHSA showed significantly improved anti‐hyperglycemic effects in oral glucose tolerance tests and enhanced hypoglycemic effects compared with exenatide in a db/db type 2 diabetes mouse model. These results suggest that the exenatide‐APTHSA fusion peptide could be used as a potential anti‐diabetic agent for the treatment of type 2 diabetes. Graphical abstract Figure. No Caption available.