Abstract Immune checkpoint inhibitors (ICIs) are effective against many advanced malignancies. However, many patients are nonresponders to immunotherapy, and overcoming this resistance to treatment is important. Boron neutron capture therapy (BNCT) is a local chemoradiation therapy with the combination of boron drugs that accumulate selectively in cancer and the neutron irradiation of the cancer site. Here, we report the first boron neutron immunotherapy (B‐NIT), combining BNCT and ICI immunotherapy, which was performed on a radioresistant and immunotherapy‐resistant advanced‐stage B16F10 melanoma mouse model. The BNCT group showed localized tumor suppression, but the anti‐PD‐1 antibody immunotherapy group did not show tumor suppression. Only the B‐NIT group showed strong tumor growth inhibition at both BNCT‐treated and shielded distant sites. Intratumoral CD8+ T‐cell infiltration and serum high mobility group box 1 (HMGB1) levels were higher in the B‐NIT group. Analysis of CD8⁺ T cells in tumor‐infiltrating lymphocytes (TILs) showed that CD62L‐ CD44⁺ effector memory T cells and CD69⁺ early‐activated T cells were predominantly increased in the B‐NIT group. Administration of CD8‐depleting mAb to the B‐NIT group completely suppressed the augmented therapeutic effects. This indicated that B‐NIT has a potent immune‐induced abscopal effect, directly destroying tumors with BNCT, inducing antigen‐spreading effects, and protecting normal tissue. B‐NIT, immunotherapy combined with BNCT, is the first treatment to overcome immunotherapy resistance in malignant melanoma. In the future, as its therapeutic efficacy is demonstrated not only in melanoma but also in other immunotherapy‐resistant malignancies, B‐NIT can become a new treatment candidate for advanced‐stage cancers.

Multidisciplinary therapy centered on radical surgery for resectable pancreatic cancer is expected to prolong prognosis, but relies on CA19-9 biomarker levels to determine treatment strategy. Boron neutron capture therapy (BNCT) is a chemoradiotherapy using tumor hyperaccumulator boron drugs and neutron irradiation. The purpose of this study is to investigate novel boron drug agents for BNCT for pancreatic cancer. Bioinformatics was used to evaluate the uptake of current boron amino acid (BPA) drugs for BNCT into pancreatic cancer. The expression of the amino acid transporter LAT1, a BPA uptake transporter, was low in pancreatic cancer and even lower in high CA19-9 pancreatic cancer. In contrast, the glucose transporter was high in high CA19-9 pancreatic cancers and inversely correlated with LAT1 expression. Considering the low EPR effect in pancreatic cancer, we synthesized a small molecule Glucose-BSH, which is boron BSH bound to glucose, and confirmed its specific uptake in pancreatic cancer. uptake of Glucose-BSH was confirmed in an environment compatible with the tumor microenvironment. The therapeutic efficacy and safety of Glucose-BSH by therapeutic neutron irradiation were confirmed with BNCT. We report Glucose-BSH boron drug discovery study of a Precision Medicine BNCT with application to high CA19-9 pancreatic cancer.

The detection of metal ions is an option for maintaining water quality and diagnosing metal ion-related diseases. In this study, we successfully detected metal ions using fluorescent peptides in water. First, we prepared seven linear (L1–L7) and seven cyclic (C1–C7) peptides containing two pyrenyl (Pyr) units and assessed the response to various metal ions by fluorescence. The results indicated that C1, which contains a hexameric cyclic peptide moiety consisting of Pyr and Gly units, did not show a fluorescent response to metal ions, while the linear L1 corresponding to C1 showed a response to Cu2+, but its selectivity was found to be poor through a competition assay for each metal ion. We then assessed C2–C7 and L2–L7, in which Gly was replaced by His units at various positions in the same manner. The results showed that C2–C7 responded to Cu2+ in a manner dependent on the His position. Additionally, superior selectivity was observed in C7 through a competition assay. These results demonstrate that the structural restriction of peptides and the sequence affect the selective detection of Cu2+ and reveal that peptides with an appropriate structure can accomplish the fluorescent detection of Cu2+ specifically.

Light that rotates in a circular spiral when viewed from the front is known as circularly polarized luminescence (CPL), and can be divided into two types, namely, left- and right-rotating light. To emit both left- and right-rotating CPLs, two types of optically active luminophores, namely, enantiomer D- and L-bodies, are generally required. This mini-review mainly discusses our latest study on CPL properties via the control of the pyrene ring as the luminescent unit incorporated into chiral peptides. In this study, optically active peptide–pyrene organoluminescent materials that emit CPL were synthesized by combining a peptide as a frame and two pyrene rings as a luminescent unit. By adjusting the interpyrene distance, external conditions, and absolute chiral configuration (D- or L-configuration), the chiral spatial configuration of the luminescent pyrene ring was precisely controlled. Consequently, the direction of CPL rotation from pyrenylalanine-containing peptides with the same configuration was successfully controlled.

A connection of a functional peptide with a cell-penetrating peptide (CPP) used a heterodimeric coiled-coil as a molecular zipper can improve the intracellular delivery and activity of the functional peptide. However, the chain length of the coiled coil required for functioning as the molecular zipper is unknown at present. To solve the problem, we prepared an autophagy-inducing peptide (AIP) that conjugates with the CPP via heterodimeric coiled-coils consisting of 1 to 4 repeating units (K/E zipper; AIP-Kn and En-CPP), and we investigated the optimum length of the K/E zipper for effective intracellular delivery and autophagy induction. Fluorescence spectroscopy showed that K/E zippers with n = 3 and 4 formed a stable 1:1 hybrid (AIP-K3/E3-CPP and AIP-K4/E4-CPP, respectively). Both AIP-K3 and AIP-K4 were successfully delivered into cells by the corresponding hybrid formation with K3-CPP and K4-CPP, respectively. Interestingly, autophagy was also induced by the K/E zippers with n = 3 and 4, more intensively by the former than by the latter. The peptides and K/E zippers used in this study did not show significant cytotoxicity. These results indicate that the effective induction of autophagy occurs via an exquisite balance of the association and dissociation of the K/E zipper in this system.

It is important to optimize the photoexcited-state conformation of chiral luminescent molecules to enhance the intensity of circularly polarized luminescence (CPL) and control the direction of CPL rotation. In pyrenyl peptide luminophores, the intensity and sign of CPL is determined by the solvent and intramolecular distance between pyrenyl units in addition to peptide chirality. However, the control of CPL properties in water is difficult, and new methods to control CPL in water are required. In this study, we achieved amplification and control of the sign of excimer-origin CPL by adding γ-cyclodextrin to a flexible bipyrenyl peptide luminophore with two arginine groups in water.

We assessed a reactivity of chloroacetyl-modified tripeptides consisting of various amino acid residues (Cl-3X) and mercaptoundecahydrododecaborate (BSH) by converting Cl-3X to its reactant (BS-3X). We showed that the Cl-3X consisting of basic amino acid residues (e.g., Arg) reacted with BSH effectively and its conversion decreased as the number of Arg residues in the Cl-3X decreased. Furthermore, a reactivity of the peptides with introduction of an alkyl linker between the triarginine and the chloroacetyl group (Cl-Cn-3R) with BSH decreased with increasing alkyl linker length. These results indicate that an electrostatic attraction of positively charged amino acid residues in the tripeptides and negatively charged BSH causes BSH to gather in a vicinity of the chloroacetyl group, resulting in an accelerated reaction. This work should aid a development of new boron agents using BSH in boron neutron capture therapy.

In a span of less than 3 years since the declaration of the coronavirus pandemic, numerous SARS-CoV-2 variants of concern have emerged all around the globe, fueling a surge in the number of cases and deaths that caused severe strain on the health care system. A major concern is whether viral evolution eventually promotes greater fitness advantages, transmissibility, and immune escape.Mutations at spike protein L452 are recurrently observed in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants of concern (VOC), including omicron lineages. It remains elusive how amino acid substitutions at L452 are selected in VOC. Here, we characterized all 19 possible mutations at this site and revealed that five mutants expressing the amino acids Q, K, H, M, and R gained greater fusogenicity and pseudovirus infectivity, whereas other mutants failed to maintain steady-state expression levels and/or pseudovirus infectivity. Moreover, the five mutants showed decreased sensitivity toward neutralization by vaccine-induced antisera and conferred escape from T cell recognition. Contrary to expectations, sequence data retrieved from the Global Initiative on Sharing All Influenza Data (GISAID) revealed that the naturally occurring L452 mutations were limited to Q, M, and R, all of which can arise from a single nucleotide change. Collectively, these findings highlight that the codon base change mutational barrier is a prerequisite for amino acid substitutions at L452, in addition to the phenotypic advantages of viral fitness and decreased sensitivity to host immunity. IMPORTANCE In a span of less than 3 years since the declaration of the coronavirus pandemic, numerous SARS-CoV-2 variants of concern have emerged all around the globe, fueling a surge in the number of cases and deaths that caused severe strain on the health care system. A major concern is whether viral evolution eventually promotes greater fitness advantages, transmissibility, and immune escape. In this study, we addressed the differential effect of amino acid substitutions at a frequent mutation site, L452 of SARS-CoV-2 spike, on viral antigenic and immunological profiles and demonstrated how the virus evolves to select one amino acid over the others to ensure better viral infectivity and immune evasion. Identifying such virus mutation signatures could be crucial for the preparedness of future interventions to control COVID-19.

Although the Omicron variant of the SARS-CoV-2 virus shows resistance to neutralizing antibody, it retains susceptibility to the cellular immune response. Here we characterize vaccine-induced T cells specific for various SARS-CoV-2 variants and identified HLA-A*24:02-restricted CD8+ T cells that strongly suppress Omicron BA.1 replication in vitro. Mutagenesis analyses revealed that a G446S mutation, located just outside the N-terminus of the cognate epitope, augmented TCR recognition of this variant. In contrast, no enhanced suppression of replication is observed against cells infected with the prototype, Omicron BA.2, and Delta variants that express G446. The enhancing effect of the G446S mutation is lost when target cells are treated with inhibitors of tripeptidyl peptidase II, a protein that mediates antigen processing. These ex vivo analysis and in vitro results demonstrate that the G446S mutation in the Omicron BA.1 variant affects antigen processing/presentation and potentiates antiviral activity by vaccine-induced T cells, leading to enhanced T cell recognition towards emerging variants.

We developed a method for detecting DNA by excimer fluorescence from two peptide nucleic acids (PNAs) modified with a pyrene (Pyr). The two PNA-Pyr probes were prepared by solid-phase peptide synthesis, and we assessed fluorescence from the mixture of probes with DNA. From the results, excimer fluorescence derived from the two PNA-Pyr probes forming hybrids with the complementary DNA was observed, and the two probes showed the maximum excimer/monomer ratio when the probes and DNA were hybridized at a 1:1:1 ratio, indicating that the PNA-Pyr probes can detect target DNA. Furthermore, we adjusted the spatial arrangement between the two PNA-Pyr hybrids formed on the DNA to promote optimal excimer formation. As a result, optimal excimer formation was achieved by spacing the two nucleobases between the formed two hybrids and further inserting a hexamethylene linker (C6) between the PNA and Pyr of the PNA-Pyr probe on one side.

In this study, we performed an elaborate adjustment of the structure of peptide nucleic acid (PNA) molecular beacons as probes for detecting nucleic acids. We synthesized the PNA beacons with various numbers of Glu, Lys, and dabcyl (Dab) quenchers in them, and we investigated their fluorescence changes (F-1/1/F-0) with and without full-match DNA. As the numbers of Glu/Lys or Dab increased, the F-1/1/F-0 tended to decrease. Among the different beacons, the PNA beacon with one Glu and one Lys (P1Q1) showed the largest F-1/1/F-0. On the other hand, a relatively large F-1/1/F-0 was obtained when the number of Glu/Lys and the number of Dab were the same, and the balance between the numbers of Glu/Lys and Dab seemed to affect the F-1/1/F-0. We also investigated the DNA detection by the prehybrid of P1Q1, which consists of the T790M base sequence, [P1Q1(T790M)], with quencher-modified DNA (Q-DNA). We examined the DNA detection with single-base mismatch by P1Q1(T790M), and we clarified that there was difficulty in detecting the sequence with P1Q1 alone, but that the sequence was successfully detected by the prehybrid of P1Q1 with the Q-DNA.

Micro RNAs (miRNAs) are involved in a variety of biological functions and are attracting attention as diagnostic and prognostic markers for various diseases. Highly sensitive RNA detection methods are required to determine miRNA expression levels and intracellular localization. In this study, we designed new double-stranded peptide nucleic acid (PNA)/DNA probes consisting of a fluorophore-PNA-quencher (fPq) and a quencher-DNA (qD) for miR-221 detection. We optimized the fPq structure, PNA-DNA hybrid length, and hybrid position. The resultant fPq-2/qD-6b probe was a 6-bp hybrid probe with a 10-base fPq and a 6-base qD. The signal-to-background ratios of the probes showed that fPq-2/qD-6b had a higher target sensitivity than fPq (PNA beacon)-type and fP/qD-type probes. The results of the detection limit and target specificity indicate that the fPq/qD probe is promising for RNA detection in both cells and cell extracts as well as for miRNA diagnosis.

Pro-apoptotic peptides may be promising agents for cancer therapy owing to their ability to induce apoptosis in cancer cells. TatBim, a fusion peptide of Tat cell-penetrating peptide (CPP) and the BH3 domain derived from Bim apoptosis-inducing protein, is a pro-apoptotic peptide. In this study, based on the TatBim sequence, we attempted to minimize the CPP-Bim peptide while retaining apoptosis-inducing activity. The CPP and Bim parts were systematically shortened, and the pro-apoptotic activities of the shortened peptides were examined. We obtained TatBim-N1C2 and R8Bim-N1C2 as minimized peptides with efficient apoptotic activity. These peptides may have potential applications in future biomedical studies, such as cancer therapeutics.

A heterodimeric leucine zipper composed of a pair of leucine zipper peptides containing acidic or basic amino acid residues at appropriate positions in each peptide was used as a molecular glue to connect protein cargos to a cell-penetrating peptide (CPP) carrier. To investigate the hybridization properties by fluorescence experiments, we prepared an enhanced green fluorescent protein (EGFP) fused with an acidic leucine zipper (LzK), EGFP-LzK, and a basic leucine zipper (LzE) modified with a CPP, LzE-CPP. The LzK and LzE formed a 1:1 hybrid when EGFP-LzK and LzE-CPP were mixed in phosphate buffer saline, thereby conjugating the EGFP with the CPP. The formation of the 1:1 hybrid was confirmed by fluorescence spectra and fluorescence titration curves. Results from fluorescence microscopy experiments showed that EGFP was successfully delivered into cells by conjugating with the CPP via formation of the LzK/LzE hybrid. We also fused the apoptotic protein p53 with LzK (p53-LzK) and investigated the inhibition of cell proliferation of various cell lines by incubation with the p53-LzK/LzE-CPP hybrid. This hybrid was found to localize in nuclei and successfully inhibited cell-specific proliferation. The LzE/LzK zipper system inhibited cell proliferation more efficiently than the directly fused conjugate, p53-CPP. Our method will be a useful drug delivery system for delivering bioactive proteins to treat various diseases.

We previously developed a conjugate consisting of B cluster BSH and tri-arginine peptide (BSH-3R). This could potentially be used as a boron agent for boron neutron capture therapy; however, it possesses poor water solubility and thus needs to be improved for use as medicine. In this study, we devised several means of improving the water solubility of BSH-3R. As one of them, we used cyclodextrin (CD), which was expected to improve the water solubility resulting from interaction of the BSH-3R with CD. We evaluated the solubility of BSH-3R in aqueous CD solution by using reverse-phase high-performance liquid chromatography. As we expected, the solubility of BSH-3R was increased in a manner dependent on the addition of β-CD and γ-CD in aqueous solution. Furthermore, we synthesized BSH conjugated to oligoarginine having various chain lengths (BSH-nR) and BSH-3R with ethylene glycol linkers introduced between BSH and 3R (BSH-nEg-3R). The water solubility of these BSH peptides was also evaluated and the results showed that the introduction of nEg to BSH-3R markedly improved the water solubility. Furthermore, we found that the water solubility of these peptides can be further improved by also applying CD. 10

Chiral organic and organometallic luminophores that possess circularly polarized luminescence (CPL) properties in the near-ultraviolet to near-infrared region have several useful applications. However, the CPL properties are subject to inherent factors of the compounds; to date, studies on the CPL properties influenced by amino acids and peptides are scarce. Consequently, we developed peptide-pyrene organic luminophores exhibiting various CPL properties. It is conceivable that the peptide-pyrene organic luminophores can be obtained as aggregates when dissolved in a solution. It is also possible that the formation of aggregates makes it difficult to accurately examine the CPL of the peptide in the solution. This study showed that the introduction of sterically hindered 2-aminoisobutyric acid (Aib) units into the peptide backbone inhibits aggregate formation. The resulting luminophores exhibit CPL properties owing to the presence of pyrene units. The results of this study can form a basis for the design of future materials that use peptide-pyrene organic luminophores.

Boron neutron capture therapy (BNCT) is a tumor selective therapy, the effectiveness of which depends on sufficient 10B delivery to and accumulation in tumors. In this study, we used self-assembling A6K peptide nanotubes as boron carriers and prepared new boron agents by simple mixing of A6K and BSH. BSH has been used to treat malignant glioma patients in clinical trials and its drug safety and availability have been confirmed; however, its contribution to BNCT efficacy is low. A6K nanotube delivery improved two major limitations of BSH, including absence of intracellular transduction and non-specific drug delivery to tumor tissue. Varying the A6K peptide and BSH mixture ratio produced materials with different morphologies-determined by electron microscopy-and intracellular transduction efficiencies. We investigated the A6K/BSH 1:10 mixture ratio and found high intracellular boron uptake with no toxicity. Microscopy observation showed intracellular localization of A6K/BSH in the perinuclear region and endosome in human glioma cells. The intracellular boron concentration using A6K/BSH was almost 10 times higher than that of BSH. The systematic administration of A6K/BSH via mouse tail vein showed tumor specific accumulation in a mouse brain tumor model with immunohistochemistry and pharmacokinetic study. Neutron irradiation of glioma cells treated with A6K/BSH showed the inhibition of cell proliferation in a colony formation assay. Boron delivery using A6K peptide provides a unique and simple strategy for next generation BNCT drugs.

Investigation of the relevance between cell cycle status and the bioactivity of exogenously delivered biomacromolecules is hindered by their time-consuming cell internalization and the cytotoxicity of transfection methods. In this study, we addressed these problems by utilizing the photochemical internalization (PCI) method using a peptide/protein-photosensitizer conjugate, which enables immediate cytoplasmic internalization of the bioactive peptides/proteins in a light-dependent manner with low cytotoxicity. To identify the cell-cycle dependent apoptosis, a TatBim peptide-photosensitizer conjugate (TatBim-PS) with apoptotic activity was photo-dependently internalized into HeLa cells expressing a fluorescent ubiquitination-based cell cycle indicator (Fucci2). Upon irradiation, cytoplasmic TatBim-PS internalization exceeded 95% for all cells classified in the G1, S, and G2/M cell cycle phases with no significant differences between groups. TatBim-PS-mediated apoptosis was more efficiently triggered by photoirradiation in the G1/S transition than in the G1 and S/G2/M phases, suggesting high sensitivity of the former phase to Bim-induced apoptosis. Thus, the cell cycle dependence of Bim peptide-induced apoptosis was successfully investigated using Fucci2 indicator and the PCI method. Since PCI-mediated cytoplasmic internalization of peptides is rapid and does not span multiple cell cycle phases, the Fucci-PCI method constitutes a promising tool for analyzing the cell cycle dependence of peptides/protein functions.

Determining the conformation of a chiral luminescent molecule in its ground state as well as in its photoexcited state is difficult. In the case of a pyrenyl peptide, the sign of its circularly polarised luminescence (CPL) is determined by the solvent or the intramolecular distance between its pyrenyl units; consequently, a new method for controlling CPL in water is required. Herein, we report that chiral LL-oligopeptide luminophores bearing two fluorescent pyrenyl and hydrophilic arginine units exhibit clear excimer-origin circularly polarised luminescence (CPL) at 480-510 nm in aqueous solution. The CPL sign is tuneable by altering the number and positions of the arginine units on the edges of the chiral peptide backbone.

We prepared eight novel chiral arginine-bipyrenyl oligopeptides with different intramolecular distances between two organic luminophore fluorescent pyrene units and investigated their chiroptical properties in water at ambient temperature. These luminophores are highly soluble in water because of the presence of two arginine units; because they carry two pyrene units, they emit strong excimer circularly polarized luminescence (CPL) in the range of 450-600 nm (vertical bar gCPL vertical bar approximate to (0.1-0.5) x 10(-2)). When the number of atoms between the two intramolecular pyrenes units was even, the sign of the CPL signals was negative (-), whereas when the atom number was odd, the sign of the CPL signals was positive (+), even in water. (C) 2020 Elsevier Ltd. All rights reserved.

Research into cancer cells that harbor gene mutations relating to anticancer drug-resistance at the single-cell level has focused on the diagnosis of, or treatment for, cancer. Several methods have been reported for detecting gene-mutated cells within a large number of non-mutated cells; however, target single nucleotide-mutated cells within a large number of cell samples, such as cancer tissue, are still difficult to analyze. In this study, a new system is developed to detect and isolate single-cancer cells expressing the T790M-mutated epidermal growth factor receptor (EGFR) mRNA from multiple non-mutated cancer cells by combining single-cell microarray chips and peptide nucleic acid (PNA)-DNA probes. The single-cell microarray chip is made of polystyrene with 62,410 microchambers (31-40 µm diameter). The T790M-mutated lung cancer cell line, NCI-H1975, and non-mutated lung cancer cell line, A549, were successfully separated into single cells in each microchambers on the chip. Only NCI-H1975 cell was stained on the chip with a fluorescein isothiocyanate (FITC)-conjugated PNA probe for specifically detecting T790M mutation. Of the NCI-H1975 cells that spiked into A549 cells, 0-20% were quantitatively analyzed within 1 h, depending on the spike concentration. Therefore, our system could be useful in analyzing cancer tissue that contains a few anticancer drug-resistant cells.

Fluorogens or luminescence materials that show manipulatable emissive responses toward various external stimuli, such as, temperature, solvent, salt, and pH, hold great promise for some applications. Hydrostatic pressure, as one external stimulus, can manipulate conformational changes in the ground state and subsequent photophysical properties in the excited state of an appropriately designed material. In this study, we controlled not only the chiroptical but also the emissive properties of smart fluorescence materials, namely peptide-pyrene conjugates, and also examined the origins of the optical properties by means of several spectroscopic techniques under high pressure. The location of the chromophores and the appended bulky substituent on the peptide scaffold play pivotal roles in influencing the pressure-induced properties. The present work gives new perspectives for energy-related luminescent materials which respond to hydrostatic pressure, providing an attractive alternative to other common external stimuli.

Cell-penetrating peptides (CPPs) are widely used for the intracellular delivery of peptides and proteins, but CPP fusion peptides and proteins are often transported by endocytosis and trapped in endosomes. Photochemical internalization (PCI) is a method for the endosomal escape of the trapped peptide or protein and release into the cytosol using light and photosensitizers. In PCI, endosomal membranes are thought to be destabilized by singlet oxygen (1O2) photogenerated from photosensitizers localized in endosomes. We previously developed CPP-cargo-photosensitizer (PS) conjugates able to photodependently enter the cytosol via the PCI mechanism. For example, TatU1A-PS (a covalent complex of Tat [CPP], U1A RNA-binding protein [cargo], and PS) can photodependently deliver RNAs into the cytosol, and TatBim-PS (a covalent complex of Tat, Bim [cargo], and PS) can photoinduce apoptosis in mammalian cells. However, for many newly created conjugates, the induction of PCI has been insufficient. We hypothesized that the amino acid linker sequence (XX) adjacent to the photosensitizer is an important determinant of PCI efficiency. In this study, using CPP-cargo-XX-PS platforms, we examined the relationship between PCI efficiency and the linker amino acid sequence near the photosensitizer. We found that hydrophobic FF and LL linkers enhanced the PCI efficiencies of both TatBim-XX-PS and TatU1A-XX-PS. The effectiveness of the linker depended, in part, on both the cargo moiety and the photosensitizer. These results may guide the design of CPP-cargo-PS conjugates conferring broad target functions for PCI and photodynamic therapy.

Development of an intracellular delivery method for functional peptides via cell-penetrating peptides (CPPs) expands peptide use in basic research and therapeutic applications. Although direct conjugation of a functional peptide with a CPP is the simplest method for delivery, this method has not always been reliable. CPPs usually contain several positively charged amino acids that potentially interact non-specifically with negatively charged molecules in cells and subsequently interfere with conjugated functional peptide function. Here we demonstrate a new intracellular delivery method for peptides in which a functional peptide is released from a positively charged CPP via peptide nucleic acids (PNAs). We prepared an 8-mer PNA conjugated to octa-arginine in tandem (PNA1-CPP) and linked its complementary PNA to an autophagy inducing peptide (PNA2-AIP) by solid-phase peptide synthesis. PNA1-CPP and PNA2-AIP formed a 1 : 1 hybrid via PNA1/PNA2 interaction, thereby indirectly but stably connecting the AIP to the CPP. PNA2-AIP was successfully delivered into cells in a hybrid formation-dependent manner and at least some portion of the PNA1-CPP/PNA2-AIP hybrids dissociated into PNA2-AIP and PNA1-CPP inside the cells. Notably, PNA2-AIP delivered to cells induced more autophagy than AIP directly conjugated to CPP (CPP-AIP). Further, the PNA hybrid did not induce significant cell death. These findings indicate that the PNA1/PNA2 hybrid can function as a molecular glue enabling the delivery of functional peptides into cells.

Chiral oligopeptide-naphthalene/Eu(III) hybridized luminophores emit strong circularly polarised solution-state luminescence (CPL) from Eu(III) at 592 and 614 nm (vertical bar g(CPL)vertical bar <= 2.1 x 10(-2)). Although the peptide ligands have matching absolute configurations, the CPL sign is controllable by varying the number of naphthalene units and peptide/Eu(iii) coordination ratio.

The present study investigated combined biological effects of peptide and miRNA in a peptide/miRNA nanocomplex. We utilized TatBim peptide as a cell-penetrating peptide-based RNA carrier with apoptotic activity. miRNA with apoptotic activity (miR-34a) was used for complex formation to investigate the additional effects of the combination with TatBim peptide. TatBim peptide and the miRNA formed nanocomplexes (approximately 250 nm in diameter), and these complexes were efficiently internalized by cells. Despite its efficient cell internalization, apoptotic activity of the nanocomplex decreased with increasing RNA content. However, photosensitizer-attachment to TatBim and photo irradiation significantly improved the apoptotic activity of the nanocomplex by facilitating dispersion of the peptide and RNA in the cytoplasm. Combined apoptotic activity of both TatBim peptide and miR-34a in the nanocomplex was demonstrated by substituting TatBim with Lipofectamine and by substituting miR-34a with scrambled siRNA. (C) 2019, The Society for Biotechnology, Japan. All rights reserved.

We synthesized a pair of compounds containing leucine zipper peptides to deliver protein cargo into cells. One is a cell-penetrating peptide (CPP) with Lz(E), a leucine zipper peptide containing negatively charged amino acids, and the other is a Nanog protein with Lz(K), a leucine zipper peptide containing positively charged amino acids. When cells were treated with these equimolar mixtures, Nanog-Lz(K) hybridized with Lz(E)-CPP was successfully delivered into the cells. Furthermore, Nanog-Lz(K) exerted its proper function after nuclear transport.

Atopic dermatitis is a chronic inflammatory skin disease involving T-helper (Th) 2 cells, eosinophils, and mast cells. Although CCR4 is a major chemokine receptor expressed on Th2 cells and regarded as a potential therapeutic target for allergic diseases, its role in atopic dermatitis remains unclear. Here, by using a hydrogel patch as a transcutaneous delivery device for ovalbumin (an antigen) and Staphylococcus aureus δ-toxin (a mast cell activator), we efficiently induced acute atopic dermatitis-like skin lesions in BALB/c mice, a strain prone to Th2 responses, which were characterized by increased numbers of eosinophils, mast cells, and CCR4-expressing Th2 cells in the skin lesions; elevated levels of total and ovalbumin-specific IgE in the sera; and increased expression of IL-4, IL-17A, IL-22, CCL17, CCL22, and CCR4 in the skin lesions. Of note, the same model was less efficient in C57BL/6 mice, a strain prone to Th1 responses. Using this atopic dermatitis model in BALB/c mice, we demonstrated that CCR4-deficiency or a CCR4 antagonist ameliorated the allergic responses. Collectively, these results demonstrate that CCR4 plays a pivotal role in skin allergic inflammation of BALB/c mice by recruiting CCR4-expressing Th2 cells and Th17 cells.

Multivalent cell-penetrating peptides (CPPs) have been reported to show enhancement in cellular uptake and endosomolytic activity. However, its application was limited to trans-delivery of cargo which is lower in cellular uptake efficiency of cargo than cis-delivery. Here, we tried the cis-delivery of cargo with multivalent CPP by preparing bioreducible dimeric CPP–cargo with apoptotic activity using TatBim peptide, a fusion of Tat CPP and Bim peptide derived from Bim apoptosis-inducing protein. Dimeric TatBim was almost twice as highly internalized by cells and significantly induced apoptosis compared to monomeric TatBim. Contribution of bioreducible linkage of dimeric TatBim towards apoptotic activity was also confirmed.

The photoexcited and ground state chiralities of enantiopure oligopeptides bearing two pyrenyl groups (DD-2/LL-2: four methylene spacer between two pyrenyl groups and DD-1/LL-1: no methylene spacer thereof) in eight common organic solvents (CHCl3, CH2Cl2, MeOH, CH3CN, DMF, NMP, DMAc, and acetone) were investigated by means of circularly polarized luminescence (CPL) and circular dichroism (CD) spectroscopies. It was found that chiroptical signs of pyrene-origin CPL and CD signals largely depend on the nature of solvents and are susceptible to the methylene spacer. Actually, the excimer-origin CPL signs at 450-510 nm of DD-1/LL-1 in DMF were (-)/(+), respectively, while those in other solvents were oppositely (+)/(-), respectively. On the other hand, in DD-2/LL-2, the excimer-origin CPL signs were (-)/(+) in CH2Cl2 (and CHCl3), respectively, and (+)/(-) in MeOH/DMF/NMP/DMAc, respectively. The solvent dependent and the methylene spacer dependent CD sign inversion of DD-1/LL-1 and DD-2/LL-2 were also found. These results led to conclude that the solvent molecule and the methylene spacer collaboratively affect both the ground state chirality and the photoexcited chirality.

A method to induce cytoplasmic peptide delivery, using ultrasound, was demonstrated using a molecular conjugate of a cell-penetrating peptide (CPP), a functional peptide, and a sonosensitizer. As a model of such molecular conjugates, TatBim-RB, consisting of the Tat CPP, the Bim apoptosis inducing peptide, and the sonosensitizer rose bengal was synthesized. CPPs have been widely used for intracellular delivery of various cargos; however, CPP-fused molecules tend to become entrapped in endosomes, as was observed for TatBim-RB molecules applied to cells. To promote escape of the entrapped TatBim-RB molecules, cells were irradiated with ultrasound, which successfully induced endosomal escape and cytoplasmic dispersion of TatBim-RB, and subsequently apoptosis. Our results suggest that this peptidesonosensitizer conjugate strategy may facilitate numerous kinds of medicinal chemistry studies, and furthermore, this specific conjugate may exhibit potential as a novel therapeutic agent for the promotion of apoptosis. (C) 2017 Elsevier Ltd. All rights reserved.

Multiple pyrenes as pendants of enantioimpure di-/tripeptides (abbreviated as N-LD-C, N-DL-C, N-LLD-C and N-DDL-C) showed pyrene-origin CPL and CD signals, which were associated with conflicting CPL-/CD-signs, compared to the corresponding enantiopure di-/tri-peptides.

A novel molecule, TatBim-Alexa, consisting of the HIV1 Tat cell-penetrating peptide, the Bim apoptosis-inducing peptide, and Alexa Fluor 546 was synthesized for photoinducion of apoptosis. The Alexa Fluor 546 was used as a photosensitizer and covalently attached at the C-terminus of TatBim peptide by the thiol-maleimide reaction. Photo-dependent cytosolic internalization of TatBim-Alexa and photo-dependent apoptosis using TatBim-Alexa were demonstrated in several kinds of mammalian cells including human cancer cell lines. (C) 2016 Elsevier Ltd. All rights reserved.

We prepared 16 novel chiral peptide-pyrene organic luminophores with different distances between the fluorescent pyrene groups and investigated their properties in CHCl3 at room temperature. The peptide-pyrene organic luminophores bearing two pyrene groups emit strong excimer circularly polarized luminescence (CPL) in the solution state. Two pendant pyrenyl groups in a series of chiral oligopeptides clearly revealed excimer CPL in chloroform at 480-490 nm (vertical bar g(em)vertical bar approximate to (2-8) x 10(-3)). When the distance between the two pyrenes increased, the sign of the CPL signals was inverted twice, while the sign of the corresponding circular dichroism (CD) signals was retained, (vertical bar g(CD)vertical bar approximate to (3-8) x 10(-5)).

Among L- and D-oligopeptides with multiple pyrenes as pendants, the dipeptides with two and three pyrenes showed blue-coloured circularly polarised luminescence as high as vertical bar g(em)vertical bar approximate to (0.86-1.1) x 10(-2) at around 450 nm, reflecting from exciton couplets of twisted pyrenes.

Glioblastoma, a malignant brain tumor with poor disease outcomes, is managed in modern medicine by multimodality therapy. Boron neutron capture therapy (BNCT) is an encouraging treatment under clinical investigation. In malignant cells, BNCT consists of two major factors: neutron radiation and boron uptake. To increase boron uptake in cells, we created a mercapto-closo-undecahydrododecaborate ([B12HnSH](2-)2Na(+), BSH) fused with a short arginine peptide (1R, 2R, 3R) and checked cellular uptake in vitro and in vivo. In a mouse brain tumor model, only BSH with at least three arginine domains could penetrate cell membranes of glioma cells in vitro and in vivo. Furthermore, to monitor the pharmacokinetic properties of these agents in vivo, we fused BSH and BSI-3R with 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA); DOTA is a metal chelating agent for labeling positron emission tomography (PET) probe with Cu-64. We administered BSH-DOTA-Cu-64 and BSH-3R-DOTA-Cu-64 to the tumor model through a mouse tail vein and determined the drugs' pharmacokinetics by PET imaging. BSH-3R showed a high uptake in the tumor area on PET imaging. We concluded that BSH-3R is the ideal boron compound for clinical use during BNCT and that in developing this compound for clinical use, the BSH-3R PET probe is essential for pharmacokinetic imaging. (C) 2015 Elsevier Ltd. All rights reserved.

An amorphous matrix of a sugar is frequently used as a bulk-forming and stabilizing agent in the food industry but tends to crystallize as the result of water uptake and increase in temperature. Additives and methods used to inhibit the crystallization of amorphous sugar (sucrose) were screened in this study. Freeze-dried amorphous sucrose containing 0.5-5 wt% of additive, including salts, different types of sugars, and polymers, the crystallization temperature (T-cry) and isothermal crystallization characteristics were examined. Certain types of salts markedly increased the Tcry and prolonged the induction period for crystal nucleation. The use of 1 wt% MgCl2 was particularly effective in inhibiting sugar crystallization. The heat treatment of crystalline sucrose under appropriate conditions was also found to result in diminished sucrose crystallization. MALDI-TOF mass spectra of the heat-treated sucrose suggested that sucrose derivatives containing multiple pyranose groups were formed, which would closely relate to the crystallization inhibition. Finally, the protein stabilizing effects of the matrices were evaluated. The results indicated that both the addition of additives and the heat treatment resulted in an improvement of the protein stabilizing effect of amorphous sugar matrix, compared to that of sucrose alone. (C) 2015 Elsevier Ltd. All rights reserved.

A hybrid comprising an autophagy-inducing peptide (AIP) and a cell-penetrating peptide (CPP) connected via heterodimeric leucine zippers was generated and delivered into cells. The hybrid successfully induced autophagy without significant cell death, while the same AIP directly connected to a CPP caused both autophagy and significant cell death.

Topical therapy is the most favored form of treatment for whitening against hyper-pigmentation and sunburn because it lends itself to self-administration, patient compliance and an absence of systemic adverse effects. However, high-molecular-weight, hydrophilic chemicals are difficult to use as transdermal delivery drugs and the use of topical drugs has been highly limited. There are now many potent tyrosinase inhibitors, for example, sulfite or kojic acid, but the efficacy of their skin transduction remains a big problem. Furthermore, melanogenesis inhibitors from natural sources have great potential, as they are considered to be safe and largely free from adverse side effects. We applied 11-arginine (11R), a cell-membrane-permeable peptide, as a transdermal delivery system with a skin delivery enhancer, pyrenbutyrate. We performed intracellular screening for melanogenesis inhibitors with 11R fused with several kinds of tyrosinase inhibitory peptides from natural sources. Of 28 tyrosinase peptides, 13 melanin synthesis inhibitory peptides were selected. Peptide No. 10 found in gliadin protein, a wheat component, most strongly inhibited melanin production. This No. 10 peptide, of only 8 amino acids, fused to 11R showed no cytotoxicity and inhibited melanin synthesis as determined through melanin content measured using an absorption spectrometer and observation with a transmission electron microscope. Next, we transduced this 11R-No. 10 into skin with an 11R transdermal delivery system after previous treatment with pyrenbutyrate and performed daily repetitive topical application for two weeks against a UV-induced sun-tanning guinea pig model. We observed a whitening effect in a model skin sample by Masson-Fontana staining and the 11R-No. 10 peptide-applied area showed significant melanogenesis inhibition. These results show that 11R using a transdermal drug delivery system with melanogenesis inhibitory peptide is a very safe and promising method for applications from cosmetics to the pharmaceutical industry. (C) 2014 Elsevier Ltd. All rights reserved.

New anti-cancer therapy with boron neutron capture therapy (BNCT) is based on the nuclear reaction of boron-10 with neutron irradiation. The median survival of BNCT patients with glioblastoma was almost twice as long as those receiving standard therapy in a Japanese BNCT clinical trial. In this clinical trial, two boron compounds, BPA (boronophenylalanine) and BSH (sodium borocaptate), were used for BNCT. BPA is taken up into cells through amino acid transporters that are expressed highly in almost all malignant cells, but BSH cannot pass through the cell membrane and remains outside the cell. We simulated the energy transfer against the nucleus at different locations of boron from outside the cell to the nuclear region with neutron irradiation and concluded that there was a marked difference between inside and outside the cell in boron localization. To overcome this disadvantage of BSH in BNCT, we used a cell-penetrating peptide system for transduction of BSH. CPP (cell-membrane penetrating peptide) is very common peptide domains that transduce many physiologically active substances into cells in vitro and in vivo. BSH-fused CPPs can penetrate the cell membrane and localize inside a cell. To increase the boron ratio in one BSH-peptide molecule, 8BSH fused to 11R with a dendritic lysine structure was synthesized and administrated to malignant glioma cells and a brain tumor mouse model. 8BSH-11R localized at the cell nucleus and showed a very high boron value in ICP results. With neutron irradiation, the 8BSH-11R administrated group showed a significant cancer killing effect compared to the 100 times higher concentration of BSH-administrated group. We concluded that BSH-fused CPPs were one of the most improved and potential boron compounds in the next-stage BNCT trial and 8BSH-11R may be applied in the clinical setting. (C) 2013 Elsevier Ltd. All rights reserved.

An indole compound with a strong purple-red color was produced by boiling a solution of indican under acidic conditions and purified by chromatographies on DEAE-650S Toyopearl TSK-gel and silica-gel columns. The purple-red compound purified was identified as indoxyl red, on the basis of FAB Mass, C-13 NMR, H-1 NMR, UV-visible spectra, and IR spectra. Although indoxyl red was first synthesized by Seidel(9) 70 years ago, very little information has been available on its characteristics. We repot here that the compound was purple-red colored at acidic pH and green at pH 13, and showed antiproliferative and cytotoxic activities to the mouse B cell lymphoma cell line NSF202. (c) 2012 Elsevier Ltd. All rights reserved.

In this report, we describe dendritic peptides possessing central fluorescent amino acids with adjacent branched amino acids. These fluorescent-peptide dendrimers were prepared using (9-fluorenyl)methoxycarbonyl (Fmoc)-based solid-phase peptide synthesis and Fmoc-derivative fluorescent and branched amino acids. The branched amino acids featured multiple carboxylic acids in their side chains, making the fluorescent-peptide dendrimers highly water-soluble compared with the analogous peptides containing the fluorescent amino acids only. The branched amino acid units also improved the fluorescence intensity of the dendrimers. Based on high-pressure liquid chromatography and fluorescence spectroscopy results, we determined that the fluorescent groups were located in the core and that the carboxylic acids were located on the surface of the dendrimers. Fluorescence resonance energy transfer was achieved among the three proximal fluorescent groups in one of the fabricated fluorescent-peptide dendrimers. (C) 2012 Wiley Periodicals, Inc.

Neutrophil serine proteases, including elastase, proteinase 3, and cathepsin G, are closely related enzymes stored in similar amounts in azurophil granules and released at the same time from triggered neutrophils at inflammatory sites. We have synthesized new fluorescence resonance energy transfer (FRET) substrates with different fluorescence donor-acceptor pairs that allow all three proteases to be quantified at the same time and in the same reaction mixture. This was made possible because the fluorescence emission spectra of the fluorescence donors do not overlap and because the values of the specificity constants were in the same range. Thus, similar activities of proteases can be measured with the same sensitivity. In addition, these substrates contain an N-terminal 2-(2-(2-aminoethoxy)ethoxy)acetic acid (PEG) moiety that makes them cell permeable. Using the mixture of these selected substrates, we were able to detect the neutrophil serine protease (NSP) activity on the activated neutrophil membrane and in the neutrophil lysate in a single measurement. Also, using the substrate mixture, we were in a position to efficiently determine NSP activity in human serum of healthy individuals and patients with diagnosed Wegener disease or microscopic polyangiitis.

Protein transduction with cell-penetrating peptides such as poly-arginine and HIV TAT peptides is widely used to deliver proteins, peptides, siRNA and biologically active compounds. It has been thought that poly-arginine peptides transduce proteins in a manner dependent on the number of arginine residues and oligo-peptides such as three arginines (3R) are ineffective. Here we showed that 3R-fused proteins were effectively delivered and functioned in cells co-treated with pyrenebutyrate, a counteranion bearing an aromatic hydrophobic moiety. Little 3R was transduced in glioma cells without pyrenebutyrate whereas the oligo-arginine was effectively delivered with pyrenebutyrate. Enhanced green fluorescence protein (eGFP) fused with 3R was effectively delivered into various kinds of cells including primary cultured cells and suspended cells in the presence of pyrenebutyrate. p53 fused with 3R (3R-p53) was delivered into glioma cells without pyrenebutyrate but could not be translocated into the ncleus. In contrast, 3R-p53 was observed in nuclei of glioma cells when co-applied with pyrenebutyrate. Although 3R-p53 was delivered less effectively than 11R-p53 with pyrenebutyrate, its transcriptional activity was higher than that of 11R-p53. Moreover, a single administration of 3R-p53 with pyrenebutyrate significantly inhibited the growth of cancer cells. These results suggest protein transduction using an oligo-arginine (3R) with pyrenebutyrate to be a good tool for the delivery of functional transcription factors and a promising method of treating cancer. (C) 2012 Elsevier Ltd. All rights reserved.

Arginine analogs were incorporated site-specifically into proteins using an in vitro translation system. In this system, mRNAs containing a CGGG codon were translated by an aminoacyl-tRNA(CCCG), which was charged with arginine analogs using yeast arginyl-tRNA synthetase. N(G)-monomethyl-L-arginine, L-citrulline and L-homoarginine were incorporated successfully into proteins using this method. The influence of arginine monomethylation in histone H3 on the acetylation of lysine residues by histone acetyltransferase hGCN5 was investigated, and the results demonstrated that K9 acetylation was suppressed by the methylation of R8 and R17 but not by R26 methylation. K18 acetylation was not affected by the methylation of R8. R17 and R26. This site-specific modification strategy provides a way to explore the roles of post-translational modifications in the absence of heterogeneity due to other modifications. (C) 2011 Elsevier Inc. All rights reserved.

We describe the fluorescence quenching-based quantification of complementary parallel and antiparallel hybrids of DNAs with pyrrolidine-based oxypeptide nucleic acids (POPNAs). When BODIPY-modified DNAs as fluorescent probe formed hybrids with complementary POPNAs, fluorescence of the BODIPY was effectively quenched by the guanine unit and the Lys unit on the POPNAs. The orientations of hybrids of POPNA with DNA were estimated by the quenching efficiencies of two BODIPY-modified DNAs. As a result, we clarified that configurations of POPNAs affect the extent of orientation of the hybrid duplexes.

To investigate the antisense effect of a pyrrolidine-based oxy-peptide nucleic acid (POPNA), we carried out the LacZ reporter assay using a 12-mer trans-L-POPNA conjugated with a cell-penetrating peptide (antisense reagent). The antisense effect of the conjugated POPNA (inhibition of LacZ activity) was comparable to that shown by a Nielsen-type peptide nucleic acid. Furthermore, the conjugated POPNA could switch the LacZ activity over a wide range of ambient temperatures. (C) 2010 Elsevier Ltd. All rights reserved.

We synthesized two dendritic ammo acids containing two or four carboxylic acids in the side chain Using these amino acids, we prepared dendritic peptides that could wrap fluorescent amino acids Because of the steric hindrance in the dendritic amino acid units present in the peptides, nonspecific adsorption of the fluorescent amino acid to gels was prevented

We synthesized 16 pyrrolidine-based oxy-peptide nucleic acid (POPNA) monomers carrying four different nucleobases onto four different stereoisomers of pyrrolidine rings. Using these monomers, we prepared POPNA oligomers, which formed sequence-specific hybrids with DNAs. The oligomer configurations influenced the hybrid stability. The oligomers were not taken into CHO cells. However, they could enter the cell cytoplasm when mixed with the influenza virus hemagglutinin peptide-arginine heptamer conjugate. (C) 2010 Elsevier Ltd. All rights reserved.

EGF receptor-binding peptides could be found by a peptide screening method using fifteen fluorescent amino acids as fluorescent tags. Of 225 peptides, we found an 8-mer peptide containing a dipeptide unit, Y-F, which was the strongest binding peptide to the EGF receptor. (c) 2010 Elsevier Ltd. All rights reserved.

We describe a new screening method for simultaneously detecting peptides that bind to a target protein by fluorescence obtained from fluorescent amino acid-modified peptides.

A peptide nucleic acid (PNA)-cell-penetrating peptide (CPP) conjugate (carrier PNA) was used as 'bridgebuilder' to connect a CPP with an shRNA. The carrier PNA successfully formed a hybrid with an shRNA bearing complementary dangling bases and the shRNA was introduced into cells by the carrier PNA, and RNAi was induced by the shRNA. Crown Copyright (C) 2009 Published by Elsevier Ltd. All rights reserved.

The profiling of microRNAs (miRNAs) using microarray technology has been used in many recent biological and medical studies. In this study, arrays of peptide nucleic acids (PNAs) were prepared and their miRNA capture abilities were evaluated. We found that the sensitivity of 10-mer PNA probes in targeting miRNAs was much higher than that of the corresponding DNA probes and also of longer (20-mer) DNA probes.

In this study, an RNA isolation method was developed using a biotinylated peptide nucleic acid (PNA) that is complementary to the target RNA. Using the biotinylated PNA method, we successfully isolated several RNAs from Escherichia coli and from human total RNA in pure form. Damage to the RNA appears to be negligible by this method because the method is rapid and does not require a high temperature treatment to facilitate RNA-PNA binding.

A novel thymine monomer of pyrrolidine-based peptide nucleic acid that contains tertiary amines in the main chain (pyrrolidine-based amino peptide nucleic acid = PAPNA) was synthesized. A mixed oligomer of two PAPNA(T) units and seven units of pyrrolidine-based oxypeptide nucleic acid (POPNA), was synthesized by a solid-phase method. The mixed oligomer was internalized into CHO cells more readily than the previous version of POPNA oligomers.

When an oxy-peptide nucleic acid that contains pyrrolidine rings (pyrrolidine-based oxy-PNA = POPNA) hybridized with its complementary DNA, a fluorophore, DiSC(2)(5), bound specifically to the hybrid in aqueous solution. Free DiSC(2)(5) did not fluoresce by itself, but the bound DiSC(2)(5) showed strong fluorescence. The fluorescence was observed only on a fully-matched POPNA-DNA hybrid, but not on hybrids with even single mismatches. This finding provides bases for highly sensitive and highly specific detection of single nucleotide polymorphisms.

A new series of oxy-peptide nucleic acids (pyrrolidine-based oxy-peptide nucleic acids = POPNAs) of four different stereoisomeric forms (cis-(L), cis-(D), trans-(L), trans-(D)) have been synthesized. To find a favorable stereoisomer of POPNA for hybridiZation with DNA or RNA, thermodynamic parameters and conformations of the hybrids between the four stereoisomers with 9 adenine bases [po(A(9))s] and dT(9) or rU(9) were investigated from ultraviolet (UV) melting curves and circular dichroism (CD) spectra. The cis-(L)-po(A(9)) formed the most stable hybrid with dT9, because of the smallest entropy loss, despite the smallest enthalpy gain. In contrast, trans-(L)-po(A(9)) formed the most stable hybrid with rU(9), because of the largest enthalpy gain, despite the largest entropy loss. The hybrid stability of trans-(L)-po(A(9)) with rU(9) was significantly improved as compared with a previous version of oxy-peptide nucleic acid (OPNA) that lacks the pyrrolidine ring. (c) 2005 Wiley Periodicals, Inc.

Four stereoisomers of oxy-peptide nucleic acids containing ether linkages in the main chain and conformationally-restricted pyrrolidine rings (pyrrolidine-based oxy-PNA = POPNA) were newly synthesized and investigated for binding to DNA. CiS-L-POPNA with 9 adenine bases formed the most stable hybrid with dT(9). The POPNA showed high sequence specificity similar to that of the Nielsen-type PNA and sharper melting behavior in hybridization with DNA than the Nielsen-type PNA.

We have developed a new series of oxy-peptide nucleic acids with pyrrolidine rings of four different types of structural isomers (cis L, cis D, trans L, trans D configurations POPNAs). Melting curves of adenine nanomers of POPNAs in the presence of the complementary DNA showed the highest Tm value for cis L-POPNA, but in the case of RNA, the highest Tm value was observed for trans L-POPNA. Thermodynamic parameters (delta H and delta S) of POPNA/DNA and POPNA/RNA hybridizations were evaluated from concentration dependence of Tm values. The POPNA/DNA and POPNA/RNA hybridizations were governed by entropy and enthalpy terms, respectively.

We describe the preparation and characterization of surface-block dendrimer, which consists of photoinitiatable xanthate groups and gold-adsorbable mercapto groups. A xanthate-modified poly(amido amine) dendrimer(generation 4, ethylenediamine core) (G 4-X) was newly prepared. G 4-X was found to form a monolayer at the air-water interface from pi -A isotherm and reflection-absorption spectroscopy. Xanthate groups of this monolayer attached to the water surface were then partially hydrolyzed with addition of the aqueous KOH to the subphase. As a result, surface-block dendrimer containing xanthate groups and mercapto groups(G 4-X-SH) was easily obtained. Quartz Crystal Microbalance measurement showed that G 4-X-SH could be immobilized onto gold substrate by using Langmuir-Blodgett method and Self-assembling method. In addition, surface property of G 4-X-SH monolayer was examined from AFM measurements.

A novel gold-adsorbable poly(gamma-benzyl-L-glutamate) has been prepared, and its adsorption processes onto gold substrates from CHCl(3) solutions have been examined by means of a quartz crystal microbalance technique, The aggregation state of the resultant polypeptide assemblies was found to be controllable on the basis of the helix-helix macrodipole interaction.

本研究は、活性を損なうことなく機能性ペプチドを細胞内へ運搬することを目的としている。そのためにペプチド核酸（以下PNA）を介して機能性ペプチドと細胞内運搬ペプチド（以下CPP）を連結-分離させる方法（PNAジッパー法）を開発している。本法によって運搬された機能性ペプチドの細胞内での活性を評価して、その有用性・汎用性を調べている。本法は細胞表面上ではなく細胞内の物質を標的にすることができ、その成果は革新的な医薬開発につながる。 今年度は、下記のように研究を実施した。 ①ペプチド合成；前年度の研究成果より機能性ペプチド修飾PNAが比較的水溶性が低いのではという懸念があらわれたので、これらの水溶性の向上を目的として機能性ペプチドとPNAの間にエチレングリコールリンカーを導入したペプチドを合成した。 ②細胞内での活性評価；①で合成したエチレングリコールリンカーを導入した機能性ペプチド（オートファジー誘導ペプチド）修飾PNAとCPP修飾PNAを用いてオートファジー誘導評価を行ったところ、エチレングリコールリンカーを挿入してもオートファジー誘導の能力はPNA間の鎖長に依存することが示唆された。一方で、エチレングリコールリンカーを導入してもそのオートファジー誘導能力には、大きな変化は見られなかったともいえた。 ③新規ペプチドジッパーの開発；PNAジッパーに代わる新しいペプチドリンカーとしてヘテロ二量体化ロイシンジッパーのロイシン部分をナフチルアラニンに置換したペプチドリンカーを合成し、そのハイブリッド形成能力について検討した。また、このヘテロ二量体化ロイシンジッパーのヘリックス含率を向上かさせるためにステイプル化にも挑戦した。

我々は、先行研究にて細胞膜透過機能を有するペプチド CPPを複数個のBSHと結合させたmulti-BSH-CPPを作成した。本プロジェクトにて、臨床応用へ向けて、さらに臨床応用へ向けたホウ素製剤へ向けて発展を行った。 a) 最小CPPを結合させたホウ素化合物BSH-3Rの開発に成功した。合成上非常に簡便であり、臨床応用な化合物である。 b)BSH-３Rは腫瘍内部への取り込み能を有しており、さらに時間経過により、核へと導入が確認された。c)本薬剤の動物における薬物動態評価を行うために、金属キレーター及び放射線各種64Cuを用いた、BSH-3R-DOTA-64CuのPET用プローブを作成した。

自己会合性ペプチドを薬剤送達方法として利用し、これにホウ素剤を添加して送達する技術を創生した。この手法により培養した悪性神経膠芽腫ならびに培養乳がん細胞に対しホウ素剤を導入できる事を示した。本法はがん幹細胞への特異性がより高いことを示した。In vivo脳腫瘍モデルマウスを作成し、このモデルマウスに対して、ホウ素導入薬剤を尾静脈から注射すると、ホウ素が腫瘍内に導入され蓄積する事を示した。ホウ素剤に陽イオンキレータを結合させ、これを介して64Cu同位体を結合させ、これが分子イメージング試薬として機能する事を示した。

私は、様々な光で励起することによって様々な光に発光するたくさんの色素(蛍光色素)を色々な配列のペプチドに連結させた。私は、そのペプチドをまとめてアルツハイマー病の原因と考えられているアミロイドβの集合体と水溶液中で混合させた。私は、そのペプチドの中からアミロイドβの集合体により強く結合するペプチドをそのペプチドに連結させた蛍光色素の蛍光発光から一度に見つけることに成功した。

水溶性の高いペプチド核酸の開発を行った。水溶性の高いペプチド核酸は細胞内に単独で導入できることが明らかとなった。しかし種々の塩基を含むペプチド核酸は天然の核酸を十分に認識することはできなかった。そこで次に、親水性が高く、そして細胞内導入能をもつペプチドを修飾したペプチド核酸を開発し、これをsiRNA のキャリアーとして用いた。これによりうまく細胞内でのmRNA の機能発現制御に成功した。

主鎖骨格中にピロリジン環を含んだオキシペプチド核酸(ピロリジン環型オキシペプチド核酸=POPNA)オリゴマーには4種類の立体構造異性体(cis-L,trans-L,cis-D,およびtrans-D)がある.我々はこれら4種類のオリゴマーを哺乳類細胞であるCHO細胞内に導入した.これらPOPNAオリゴマーは単独では細胞内に導入することができなかったが,細胞内導入ペプチドとPOPNAオリゴマーとを連結させることにより,効率よく細胞内に導入することができた.さらに,細胞内導入ペプチドとエンドソーム破壊ペプチドであるHA2を連結させたオリゴマーと共存させることにより,細胞質内に速やかに移行させることに成功した.これらの結果はPOPNAのいずれの立体構造異性体からも得られた.我々はさらに大腸菌内へも効率的にPOPNAオリゴマーを導入することについても検討した.上述の結果を参考に,POPNAオリゴマーに細胞膜破壊ペプチドであるKFF配列を連結させたコンジュゲートを作製し,そのコンジュゲートによる大腸菌内でのアンチセンス効果を調べたところ,POPNAオリゴマーがうまく細胞膜破壊ペプチドにより大腸菌内に輸送され,POPNAの塩基配列に対して特異的にアンチセンス効果が得られることがわかった.これらの結果はPOPNAオリゴマーがアンチセンス試薬として細胞内で利用できることを示しており,将来的に核酸医薬として期待できることを示唆している.