Seongmin Cho

Cancer cachexia is a complex metabolic syndrome characterized by progressive skeletal muscle wasting and poor clinical outcomes. Previous studies have mainly focused on the association between cancer-derived extracellular vesicles and atrophy of differentiated myotubes, whereas their effects on myoblast differentiation markers have not been sufficiently elucidated. In this exploratory in vitro study, vesicle fractions isolated from MC38, CT26, MCA205, and B16F10 cancer cell lines under serum-deprived conditions were referred to as small extracellular vesicles (sEVs) and used to treat C2C12 myoblasts during differentiation. Compared with the control group, the sEV-treated groups showed reduced myotube diameter and differentiation area on day 6, while the mRNA expression patterns of MyoD, MyoG (Myogenin), MRF4, Myf5, Pax7, and several MHC isoforms showed time-dependent changes. GO/KEGG analysis of commonly identified proteins revealed enrichment of terms related to mRNA metabolism, the cell cycle, and the proteasome. These findings suggest that treatment with cancer cell-derived sEVs may be associated with impaired in vitro differentiation of C2C12 myoblasts.

The development of effective cancer vaccines remains a major challenge in oncology, largely due to limited antigen delivery and suboptimal T cell priming. Here, we report RMAD1, a novel human-derived cell-penetrating peptide (CPP) originating from the ADARB2 (Adenosine Deaminase RNA Specific B2) protein, identified through an intra-dermal delivery technology (IDDT) platform, and evaluate its potential as a vaccine delivery enhancer. RMAD1 exhibited superior intracellular delivery compared with conventional CPPs and preferential uptake by antigen-presenting cells (APCs), including dendritic cells and macrophages. RMAD1 conjugated vaccines showed enhanced accumulation in draining lymph nodes and facilitated efficient antigen cross-presentation through the MHC class I pathway. In murine E.G7-OVA and TC-1 tumor models, RMAD1 conjugated vaccines induced robust antigen-specific CD8⁺ T cell responses across peripheral blood, lymphoid organs, and tumor tissues. Functional analyses revealed increased IFN-γ and TNF-α production by both CD8⁺ and CD4⁺ T cells, accompanied by a reduction in Foxp3⁺CD25⁺ regulatory T cells. In addition, RMAD1 conjugation promoted epitope spreading and established durable immunological memory, resulting in protection against tumor rechallenge. Therapeutic efficacy was further demonstrated in a TC-1 lung metastasis model, where RMAD1-based vaccination significantly reduced metastatic burden. Importantly, RMAD1-vaccinated mice exhibited therapeutic efficacy comparable to cisplatin treatment, while demonstrating a favorable safety profile. Together, these findings position RMAD1 as a next-generation CPP platform that outperforms existing peptides in enhancing antigen delivery and anti-tumor immunity, offering a promising strategy for advancing cancer vaccine development.

Anti-pigmentation peptides have been developed as alternative skin-lightening agents to replace conventional chemicals that have adverse effects on the skin. However, the maximum size of these peptides is often limited by their low skin and cell penetration. To address this issue, we used our intra-dermal delivery technology (IDDT) platform to identify peptides with hypo-pigmenting and high cell-penetrating activity. Using our cell-penetrating peptides (CPPs) from the IDDT platform, we identified RMNE1 and its derivative RMNE3, “DualPep-Shine”, which showed levels of α-Melanocyte stimulating hormone (α-MSH)-induced melanin inhibition comparable to the conventional tyrosinase inhibitor, Kojic acid. In addition, DualPep-Shine was delivered into the nucleus and regulated the gene expression levels of melanogenic enzymes by inhibiting the promoter activity of microphthalmia-associated transcription factor-M (MITF-M). Using a 3D human skin model, we found that DualPep-Shine penetrated the lower region of the epidermis and reduced the melanin content in a dose-dependent manner. Furthermore, DualPep-Shine showed high safety with little immunogenicity, indicating its potential as a novel cosmeceutical ingredient and anti-pigmentation therapeutic agent.

Glycyl‐tRNA synthetase 1 (GARS1), a cytosolic enzyme secreted from macrophages, promotes apoptosis in cancer cells. However, the mechanism underlying GARS1 secretion has not been elucidated. Here, we report that GARS1 is secreted through unique extracellular vesicles (EVs) with a hydrodynamic diameter of 20–58 nm (mean diameter: 36.9 nm) and a buoyant density of 1.13–1.17 g/ml. GARS1 was anchored to the surface of these EVs through palmitoylated C390 residue. Proteomic analysis identified 164 proteins that were uniquely enriched in the GARS1‐containing EVs (GARS1‐EVs). Among the identified factors, insulin‐like growth factor II receptor, and vimentin also contributed to the anti‐cancer activity of GARS1‐EVs. This study identified the unique secretory vesicles containing GARS1 and various intracellular factors that are involved in the immunological defence response against tumorigenesis.

A tRNA synthase in metabolic control: Leucyl-tRNA synthetase 1 (LARS1), which covalently couples leucine to its cognate transfer RNAs (tRNAs), appears to have broader roles in the control of leucine metabolism. The enzyme also serves as a leucine sensor for the mechanistic target of rapamycin complex 1 (mTORC1), which regulates protein synthesis, metabolism, autophagy, and cell growth. Yoon et al. show that in cells deprived of glucose, LARS1 is phosphorylated by Unc-51 like autophagy activating kinase 1 (see the Perspective by Lehman and Abraham). This phosphorylation decreases leucine binding to LARS1 and, in turn, should decrease translation, reduce activation of mTORC1, and perhaps free up leucine for use in the generation of adenosine triphosphate in glucose-starved cells. Science , this issue p. 205 ; see also p. 146

Background The generation of antigen-specific cytotoxic T lymphocyte (CTL) responses is required for successful cancer vaccine therapy. In this regard, ligands of Toll-like receptors (TLRs) have been suggested to activate adaptive immune responses by modulating the function of antigen-presenting cells (APCs). Despite their therapeutic potential, the development of TLR ligands for immunotherapy is often hampered due to rapid systemic toxicity. Regarding the safety concerns of currently available TLR ligands, finding a new TLR agonist with potent efficacy and safety is needed. Methods A unique structural domain (UNE-C1) was identified as a novel TLR2/6 in the catalytic region of human cysteinyl-tRNA synthetase 1 (CARS1) using comprehensive approaches, including RNA sequencing, the human embryonic kidney (HEK)-TLR Blue system, pull-down, and ELISA. The potency of its immunoadjuvant properties was analyzed by assessing antigen-specific antibody and CTL responses. In addition, the efficacy of tumor growth inhibition and the presence of the tumor-infiltrating leukocytes were evaluated using E.G7-OVA and TC-1 mouse models. The combined effect of UNE-C1 with an immune checkpoint inhibitor, anti-CTLA-4 antibody, was also evaluated in vivo. The safety of UNE-C1 immunization was determined by monitoring splenomegaly and cytokine production in the blood. Results Here, we report that CARS1 can be secreted from cancer cells to activate immune responses via specific interactions with TLR2/6 of APCs. A unique domain (UNE-C1) inserted into the catalytic region of CARS1 was determined to activate dendritic cells, leading to the stimulation of robust humoral and cellular immune responses in vivo. UNE-C1 also showed synergistic efficacy with cancer antigens and checkpoint inhibitors against different cancer models in vivo. Further, the safety assessment of UNE-C1 showed lower systemic cytokine levels than other known TLR agonists. Conclusions We identified the endogenous TLR2/6 activating domain from human cysteinyl-tRNA synthetase CARS1. This novel TLR2/6 ligand showed potent immune-stimulating activity with little toxicity. Thus, the UNE-C1 domain can be developed as an effective immunoadjuvant with checkpoint inhibitors or cancer antigens to boost antitumor immunity.

Exosomal secretion of truncated cytosolic lysyl-tRNA synthetase induces inflammation during cell starvation –

Aminoacyl-tRNA synthetases (ARSs), enzymes that normally control protein synthesis, can be secreted and have different activities in the extracellular space, but the mechanism of their secretion is not understood. This study describes the secretion route of the ARS lysyl-tRNA synthetase (KRS) and how this process is regulated by caspase activity, which has been implicated in the unconventional secretion of other proteins. We show that KRS is secreted from colorectal carcinoma cells within the lumen of exosomes that can trigger an inflammatory response. Caspase-8 cleaved the N-terminal of KRS, thus exposing a PDZ-binding motif located in the C terminus of KRS. Syntenin bound to the exposed PDZ-binding motif of KRS and facilitated the exosomic secretion of KRS dissociated from the multi-tRNA synthetase complex. KRS-containing exosomes released by cancer cells induced macrophage migration, and their secretion of TNF-α and cleaved KRS made a significant contribution to these activities, which suggests a novel mechanism by which caspase-8 may promote inflammation.