bims-cepepe Biomed News
on Cell-penetrating peptides
Issue of 2025–01–26
fourteen papers selected by
Henry Lamb, Queensland University of Technology



  1. Chem Biol Drug Des. 2025 Jan;105(1): e70051
      Drug targeting strategies, such as peptide-drug conjugates (PDCs), have arisen to combat the issue of off-target toxicity that is commonly associated with chemotherapeutic small molecule drugs. Here we investigated the ability of PDCs comprising a human protein-derived cell-penetrating peptide-platelet factor 4-derived internalization peptide (PDIP)-as a targeting strategy to improve the selectivity of camptothecin (CPT), a topoisomerase I inhibitor that suffers from off-target toxicity. The intranuclear target of CPT allowed exploration of PDC design features required for optimal potency. A suite of PDCs with various structural characteristics, including alternative conjugation strategies (such as azide-alkyne cycloaddition and disulfide conjugation) and linker types (non-cleavable or cleavable), were synthesized and investigated for their anticancer activity. Membrane permeability and cytotoxicity studies revealed that intact PDIP-CPT PDCs can cross membranes, and that PDCs with disulfide- and protease-cleavable linkers liberated free CPT and killed melanoma cells with nanomolar potency. However, selectivity of the PDIP carrier peptide for melanoma compared to noncancerous epidermal cells was not maintained for the PDCs. This study emphasizes the distinct role of the peptide, linker, and drug for optimal PDC activity and highlights the need to carefully match components when assembling PDCs as targeted therapies.
    Keywords:  camptothecin; cell‐penetrating peptide; cleavable linker; melanoma; peptide–drug conjugate
    DOI:  https://doi.org/10.1111/cbdd.70051
  2. Chem Commun (Camb). 2025 Jan 24.
      A two-step, biocompatible strategy enables site-specific generation of branched and macrocyclic peptide-protein conjugates. Solvent-exposed cysteines on proteins are modified by a small bifunctional reagent at near-physiological pH, followed by cyanopyridine-aminothiol click reactions to create branched or macrocyclic peptide architectures. This method offers design strategies for next-generation protein therapeutics.
    DOI:  https://doi.org/10.1039/d4cc06442a
  3. Sci Adv. 2025 Jan 24. 11(4): eadr8638
      Designing binders to target undruggable proteins presents a formidable challenge in drug discovery. In this work, we provide an algorithmic framework to design short, target-binding linear peptides, requiring only the amino acid sequence of the target protein. To do this, we propose a process to generate naturalistic peptide candidates through Gaussian perturbation of the peptidic latent space of the ESM-2 protein language model and subsequently screen these novel sequences for target-selective interaction activity via a contrastive language-image pretraining (CLIP)-based contrastive learning architecture. By integrating these generative and discriminative steps, we create a Peptide Prioritization via CLIP (PepPrCLIP) pipeline and validate highly ranked, target-specific peptides experimentally, both as inhibitory peptides and as fusions to E3 ubiquitin ligase domains. PepPrCLIP-derived constructs demonstrate functionally potent binding and degradation of conformationally diverse, disease-driving targets in vitro. In total, PepPrCLIP empowers the modulation of previously inaccessible proteins without reliance on stable and ordered tertiary structures.
    DOI:  https://doi.org/10.1126/sciadv.adr8638
  4. RSC Chem Biol. 2025 Jan 15.
      Peptide stapling is an effective strategy to stabilise α-helical peptides, enhancing their bioactive conformation and improving physiochemical properties. In this study, we apply our novel diyne-girder stapling approach to the MDM2/MDMX α-helical binding region of the p53 transactivation domain. By incorporation of an unnatural amino acid to create an optimal i, i + 7 bridge length, we developed a highly α-helical stapled peptide, 4, confirmed via circular dichroism. This diyne-girder-stapled peptide demonstrated enhanced helicity and nanomolar binding affinity for MDM2, as assessed by fluorescence polarisation. Crucially, peptide 4 exhibited strong selectivity for MDM2, with approximately 100-fold reduced affinity for MDMX. Molecular modeling and docking studies suggested that this selectivity arose from diminished hydrophobic interactions at the MDMX binding site, driven by the diyne-girder's constrained geometry. The use of the diyne-girder, a unique feature amongst stapled peptide analogues, for cellular visualisation using Raman spectroscopy in the "cell-silent" region was explored. This capability potentially offers a novel method for tracking stapled peptides in biological systems without the need for large fluorophores. Overall, peptide 4 represents a promising tool for probing MDM2 activity and a valuable addition to the arsenal of peptide-based therapeutic strategies.
    DOI:  https://doi.org/10.1039/d4cb00288a
  5. ACS Infect Dis. 2025 Jan 22.
      Plants provide an abundant source of potential therapeutic agents, including a diverse array of compounds, such as cyclotides, which are peptides known for their antimicrobial activity. Cyclotides are multifaceted molecules with a wide range of biological activities. Their unique topology forms a head-to-tail cyclic structure reinforced by a cysteine knot, which confers chemical and thermal stability. These molecules can directly target membranes of infectious agents by binding to phosphatidylethanolamine in lipid membranes, leading to membrane permeabilization. Additionally, they function as carriers and cell-penetrating molecules, demonstrating antiviral, antibacterial, antifungal, and nematicidal properties. The structure of cyclotides is also amenable to chemical synthesis, facilitating drug design through residue substitutions or grafting of bioactive epitopes within the cyclotide scaffold to enhance peptide stability. In this review, we explore the multifunctionality of these biomolecules as anti-infective agents, emphasizing their potential as a novel class of antimicrobial drugs.
    Keywords:  Cyclotides; PAMPs; anti-infectives; multifunctionality
    DOI:  https://doi.org/10.1021/acsinfecdis.4c00957
  6. Chem Asian J. 2025 Jan 20. e202401734
      Intracellular delivery of proteins is an important barrier in the development of strategies to deliver functional proteins and protein therapeutics into the cells to realize their full potential in biotechnology, biomedicine, cell-based therapies, and gene editing protein systems. Most of the intracellular protein delivery strategies involve the conjugation of cell penetrating peptides to enable and enhance the permeability of plasma membrane of mammalian cells to allow proteins to enter cytosol. Small molecules conjugations such as (p-methylphenyl) glycine, pyrenebutyrate and cysteines are used for the same purpose. The molecular level interactions are governed mostly by ionic (cationic/anionic), covalent and non-covalent interactions with various molecular entities of glycocalyx matrix on plasma membrane lipid bilayer. Although the role of non-covalent interactions is not fully understood, it is intriguing to see the recent advances in the non-covalent interaction-based strategies of intracellular delivery of small molecules and proteins into mammalian cells. These are achieved by simple modification of proteins' surface with chemical moieties which can form non-covalent interactions other than hydrogen bonding. In this review, we describe the recent advances and the mechanistic aspects of intracellular delivery and role of non-covalent interactions during the cellular uptake of proteins and small molecules.
    Keywords:  cellular uptake; chalcogen bonding; halogen bonding; membrane transport; unnatural amino acids
    DOI:  https://doi.org/10.1002/asia.202401734
  7. Drug Discov Today. 2025 Jan 20. pii: S1359-6446(25)00013-3. [Epub ahead of print] 104300
      Protein-protein interactions (PPIs) are fundamental to a variety of biological processes, but targeting them with small molecules is challenging because of their large and complex interaction interfaces. However, peptides have emerged as highly promising modulators of PPIs, because they can bind to protein surfaces with high affinity and specificity. Nonetheless, computational peptide design remains difficult, hindered by the intrinsic flexibility of peptides and the substantial computational resources required. Recent advances in artificial intelligence (AI) are paving new paths for peptide-based drug design. In this review, we explore the advanced deep generative models for designing target-specific peptide binders, highlight key challenges, and offer insights into the future direction of this rapidly evolving field.
    Keywords:  artificial intelligence; deep generative models; peptide design; protein-peptide interactions; protein-protein interactions
    DOI:  https://doi.org/10.1016/j.drudis.2025.104300
  8. Front Artif Intell. 2024 ;7 1497307
      Cell-penetrating peptides (CPPs) are highly effective at passing through eukaryotic membranes with various cargo molecules, like drugs, proteins, nucleic acids, and nanoparticles, without causing significant harm. Creating drug delivery systems with CPP is associated with cancer, genetic disorders, and diabetes due to their unique chemical properties. Wet lab experiments in drug discovery methodologies are time-consuming and expensive. Machine learning (ML) techniques can enhance and accelerate the drug discovery process with accurate and intricate data quality. ML classifiers, such as support vector machine (SVM), random forest (RF), gradient-boosted decision trees (GBDT), and different types of artificial neural networks (ANN), are commonly used for CPP prediction with cross-validation performance evaluation. Functional CPP prediction is improved by using these ML strategies by using CPP datasets produced by high-throughput sequencing and computational methods. This review focuses on several ML-based CPP prediction tools. We discussed the CPP mechanism to understand the basic functioning of CPPs through cells. A comparative analysis of diverse CPP prediction methods was conducted based on their algorithms, dataset size, feature encoding, software utilities, assessment metrics, and prediction scores. The performance of the CPP prediction was evaluated based on accuracy, sensitivity, specificity, and Matthews correlation coefficient (MCC) on independent datasets. In conclusion, this review will encourage the use of ML algorithms for finding effective CPPs, which will have a positive impact on future research on drug delivery and therapeutics.
    Keywords:  artificial neural network; cell-penetrating peptides; machine learning; mechanism; random forest; support vector machine
    DOI:  https://doi.org/10.3389/frai.2024.1497307
  9. Adv Sci (Weinh). 2025 Jan 22. e2410288
      In triple-negative breast cancer (TNBC), pro-tumoral macrophages promote metastasis and suppress the immune response. To target these cells, a previously identified CD206 (mannose receptor)-binding peptide, mUNO was engineered to enhance its affinity and proteolytic stability. The new rationally designed peptide, MACTIDE, includes a trypsin inhibitor loop, from the Sunflower Trypsin Inhibitor-I. Binding studies to recombinant CD206 revealed a 15-fold lower KD for MACTIDE compared to parental mUNO. Mass spectrometry further demonstrated a 5-fold increase in MACTIDE's half-life in tumor lysates compared to mUNO. Homing studies in TNBC-bearing mice shows that fluorescein (FAM)-MACTIDE precisely targeted CD206+ tumor-associated macrophages (TAM) upon intravenous, intraperitoneal, and even oral administration, with minimal liver accumulation. MACTIDE was conjugated to Verteporfin, an FDA-approved photosensitizer and YAP/TAZ pathway inhibitor to create the conjugate MACTIDE-V. In the orthotopic 4T1 TNBC mouse model, non-irradiated MACTIDE-V-treated mice exhibited anti-tumoral effects comparable to those treated with irradiated MACTIDE-V, with fewer signs of toxicity, prompting further investigation into the laser-independent activity of the conjugate. In vitro studies using bone marrow-derived mouse macrophages showed that MACTIDE-V excluded YAP from the nucleus, increased phagocytic activity, and upregulated several genes associated with cytotoxic anti-tumoral macrophages. In mouse models of TNBC, MACTIDE-V slowed primary tumor growth, suppressed lung metastases, and increased markers of phagocytosis and antigen presentation in TAM and monocytes, increasing the tumor infiltration of several lymphocyte subsets. MACTIDE-V is proposed as a promising peptide-drug conjugate for modulating macrophage function in breast cancer immunotherapy.
    Keywords:  CD206; peptide‐drug conjugate; targeting peptides; triple negative breast cancer; tumor‐associated macrophages
    DOI:  https://doi.org/10.1002/advs.202410288
  10. RSC Med Chem. 2024 Dec 21.
      A peptide segment that is 10 residues long at the C-terminal (CT) region of Cx43 is known to be involved in interactions, both with the Cx43 protein itself and with other proteins, that result in hemichannel (HC) activity regulation. Previously reported mimetic peptides based on this region (e.g., αCT1, CT10) have been revealed to be promising therapeutic agents in the context of cardiovascular diseases. In this work, novel approaches, such as C- and N-terminal modification and cyclization, to improve the proteolytic stability and bioavailability of the CT10 peptide are presented. These efforts resulted in a set of unprecedented potent cyclic inhibitors of HC-mediated ATP release with a half-life largely exceeding 24 hours. Additionally, the introduction of a lipophilic moiety with different solubilizing linkers led to the generation of a novel series of water-soluble and lipidated peptides that exhibited high inhibitory capacity in in vitro assays at submicromolar concentrations. A cardiac endothelium targeting strategy was also adopted, exploiting the ability of the CRPPR peptide to selectively deliver the peptides to endothelial cells.
    DOI:  https://doi.org/10.1039/d4md00850b
  11. J Nucl Med. 2025 Jan 23. pii: jnumed.124.268689. [Epub ahead of print]
      Fibroblast activation protein (FAP) has been considered a promising target for tumor imaging and therapy. This study designed a novel peptide, FAP-HXN, specifically targeting FAP and exhibiting significant potential as a radionuclide-labeled theranostic agent. Preclinical studies were conducted to evaluate the potency, selectivity, and efficacy of FAP-HXN. Methods: FAP-HXN was synthesized and characterized for selectivity and specificity toward FAP. Cellular uptake of the radiolabeled FAP-HXN in human embryonic kidney (HEK)-293-FAP cells with high expressions of FAP was evaluated. The diagnostic and therapeutic potential of 68Ga- and 177Lu-labeled radioligands was evaluated in HEK-293-FAP tumor-bearing mice compared with the FAP-targeting peptide FAP-2286. Results: FAP-HXN demonstrated high binding ability to human and mouse sources of FAP. Moreover, the in vivo studies confirmed the high affinity and specificity of radiolabeled FAP-HXN. Small-animal PET imaging demonstrated that [68Ga]Ga-FAP-HXN had continuous tumor uptake in FAP-positive tumors after administration compared with [68Ga]Ga-FAP-2286. In the therapeutic experiments, [177Lu]Lu-FAP-HXN showed significant antitumor activity in HEK-293-FAP xenografts at well-tolerated doses, which also exhibited longer tumor retention and better tumor growth inhibition compared with [177Lu]Lu-FAP-2286. Conclusion: The preclinical studies revealed that radiolabeled FAP-HXN had high tumor uptake, prolonged retention, and significant anticancer efficacy in HEK-293-FAP xenografts. FAP-HXN shows promising potential as a novel theranostic radioligand for FAP-positive tumors.
    Keywords:  FAP; cancer-associated fibroblasts; peptide; radiopharmaceutical; theranostic
    DOI:  https://doi.org/10.2967/jnumed.124.268689
  12. EJNMMI Radiopharm Chem. 2025 Jan 22. 10(1): 5
       BACKGROUND: Cancer immunotherapy is a relatively new approach to cancer treatment. Peptides that target specific pathways and cells involved in immunomodulation can potentially improve the efficacy of cancer therapy. Recently, we reported iPD-L1 as a novel inhibitor peptide that specifically targets the cancer cell ligand PD-L1 (programmed death ligand 1). PD-L1 is responsible for inhibiting the immune checkpoint protein PD-1 expressed by regulatory T cells. On the other hand, anti-PD-L1 immunotherapy in combination with external beam radiotherapy has shown improved outcomes in the treatment of breast and lung cancer. The aim of this research was to prepare 177Lu-labeled iPD-L1 and to preclinically evaluate its radiotherapeutic potential and role as a tumor immunomodulator by measuring macrophage activation, IL-10, TGFβ, and PD-L1 expression in 4T1 triple-negative breast cancer cells and murine 4T1 tumors after treatment with 177Lu-iPD-L1.
    RESULTS: The iPD-L1 ligand, characterized by UPLC mass, UV-Vis, and FT-IR spectroscopies, showed a chemical purity of 99%. The 177Lu-iPD-L1 radiochemical purity was 98.9 ± 1.1%. In vitro and in vivo studies demonstrated radiotracer stability in human serum (> 97% after 24 h evaluated by radio-HPLC), adequate affinity by the PDL1 protein (IC50 = 4.21 nM), and specific detection for PD-L1 assessed in 4T1, HCT116, and AR42J cancer cells, in which PD-L1 expression was verified by immunofluorescence and Western Blot assays. After treatment with 177Lu-iPD-L1 (0.4 Bq/cell), flow cytometry results showed a significant decrease in cell viability of 4T1 cells (dead 56.2%) compared to 177LuCl3 (dead 34.2%) and untreated cells (dead 9.4%). With high tumor uptake (6.97 ± 1.04%ID) and hepatobiliary and renal clearance, lutetium-177-labeled iPD-L1 delivered a tumor dose of 27 Gy/37 MBq and less than 0.36 Gy/37 MBq to non-source organs. PD-L1 positive tumors showed a significant increase in activated macrophages, PD-L1, IL-10, and TGFβ expression levels after 177Lu-iPD-L1 treatment as evaluated by ELISA assay and immunohistochemistry.
    CONCLUSIONS: Therefore, this study warrants further dosimetric and clinical studies to determine the immunomodulatory effect and therapeutic efficacy of 177Lu-iPD-L1 in treating PD-L1-positive tumors in combination with anti-PD-1/PD-L1 immunotherapy protocols.
    Keywords:   177Lu targeted radiation therapy; 177Lu-labeled iPD-L1; Immunotherapy; PD-1
    DOI:  https://doi.org/10.1186/s41181-025-00328-9
  13. Anticancer Agents Med Chem. 2025 Jan 23.
       OBJECTIVE: In this study, 25 synthetic cyclic lipopeptides (CLPs) were investigated for their anticancer potential against mouse melanoma (B16F10) cells, human prostate cancer (PC-3), human colorectal adenocarcinoma (HT-29) and mouse embryonic fibroblast (NIH3T3) cells.
    METHODS: The cytotoxic activity of investigated compounds was evaluated using MTT and CV assays. In order to examine the mechanism of action of the most potent compound cell cycle analysis, apoptosis assay, caspase activity, CFSE and DHR staining, DAF-FM, autophagy and immunocytochemistry caspase-3 assays were performed.
    RESULTS: During the fast screening, compound 9, was identified as prospective active CLP against B16F10 cell line at 10 μM concentration. MTT and CV assays exhibited at least four times higher cytotoxic potential of 9 (IC50 = 8.4±1.3 μM, MTT; 10.6±1.1 μM, CV) in comparison to control drug natural occurring CLP surfactin (IC50 = 50.3±0.6 μM, MTT; 40.4±0.3 μM, CV). The use of flow cytometry analysis confirmed that apoptosis was involved in the death of B16F10 cells after treatment with 9, as demonstrated also by DAPI staining. Caspase activity could be detected during cell death (ApoStat assay, immunocytochemistry caspase-3 assay). Compound 9 provokes enhancement of nitric oxide (NO) production in B16F10 cells but does not trigger ROS/RNS generation or autophagy.
    CONCLUSION: The study highlights synthetic compound 9 superior tumor-specificity and potential as an anticancer agent compared to surfactin and cisplatin. These findings could guide the development of more selective and less harmful macrocyclic lipopeptides for cancer therapy.
    Keywords:  Macrocycles; ROS/RNS production.; apoptosis; caspase; cell cycle analysis; cytotoxicity; lipopeptides
    DOI:  https://doi.org/10.2174/0118715206351208250102114944
  14. Anal Bioanal Chem. 2025 Jan 21.
      Extracellular vesicles (EVs) have been demonstrated to own the advantages in evading phagocytosis, crossing biological barriers, and possessing excellent biocompatibility and intrinsic stability. Based on these characteristics, EVs have been used as effective therapeutic carriers for drug delivery, but the low drug loading capacity greatly limits further applications. Herein, we developed a drug loading method based on cell-penetrating peptide (CPP) to enhance the encapsulation of therapeutic reagents in EVs, and EVs-based drug delivery system achieved higher killing efficacy to tumor cells. Urinary EVs and chemotherapy reagent doxorubicin (DOX) were used as model. It is easy to conjugate CPP with DOX (CPP-DOX) through the linker N-succinimidyl 3-maleimidopropionate (SMP). CPP-DOX was incubated with EVs under a mild condition, promoting the encapsulation of DOX into EV cavities. CPP-DOX-EVs showed strong anticancer ability since EVs delivery facilitated the uptake by cancer cells. EVs loading of CPP-DOX exhibited higher drug loading efficiency at 37.18%, presenting about 2.5 times increase in efficiency over EVs loading of DOX through passive incubation. Easy operation and controllable condition further reinforce the advantages compared with other loading methods. CPP-based drug loading method provides an effective strategy for EVs-based drug delivery system.
    Keywords:  Cell-penetrating peptide; Doxorubicin; Extracellular vesicles; Loading method
    DOI:  https://doi.org/10.1007/s00216-025-05742-1