Capsaicin indirectly regulates TRPA1 via the arachidonic acid cascade, resulting in TJ opening.

Capsaicin induces the reversible opening of tight junctions (TJs) and enhances the delivery of hydrophilic macromolecules through a paracellular route. We previously revealed that TRPA1 is involved in the capsaicin-induced Ca2+ influx and TJ permeability increase, although there are no reports that capsaicin directly activates TRPA1. In this study, we investigated the upstream factors of TRPA1 using RNA-seq analysis, and found that the cyclooxygenase 2 (COX2) gene was upregulated by capsaicin.

RSK4 confers paclitaxel resistance to ovarian cancer cells, which is resensitized by its inhibitor BI-D1870.

Many ovarian cancers initially respond well to chemotherapy, but often become drug-resistant after several years. Therefore, analysis of drug resistance mechanisms and overcoming resistance are urgently needed. Paclitaxel is one of the first-choice and widely-used drugs for ovarian cancer, but like most drugs, drug resistance is observed in subsequent use.

X-Ray Conformation and Structure-Activity Relationships of MA026, a Reversible Tight Junction Opener.

MA026, a cyclic lipodepsipeptide, opens the tight junction (TJ) probably via binding to claudin-1. We reported that (1) TJ-opening activity is dependent on the amino acid sequence order at Glu10-Leu11; (2) an epimer at the C3 position of the -terminal acyl tail decreased the TJ-opening activity; and (3) the epimers D-Leu1/L-Gln6 and L-Leu1/D-Gln6 showed more potent TJ-opening activity than natural MA026, although no systematic structure-activity relationship (SAR) study was conducted. Here, we report the three-dimensional structure and systematic SAR study of MA026.

Mutational Biosynthesis of Hitachimycin Analogs Controlled by the β-Amino Acid-Selective Adenylation Enzyme HitB.

Hitachimycin is a macrolactam antibiotic with an ()-β-phenylalanine (β-Phe) at the starter position of its polyketide skeleton. ()-β-Phe is formed from l-α-phenylalanine by the phenylananine-2,3-aminomutase HitA in the hitachimycin biosynthetic pathway. In this study, we produced new hitachimycin analogs via mutasynthesis by feeding various ()-β-Phe analogs to a Δ strain.

Dual Inhibition of γ-Tubulin and Plk1 Induces Mitotic Cell Death.

α/β-Tubulin inhibitors that alter microtubule (MT) dynamics are commonly used in cancer therapy, however, these inhibitors also cause severe side effects such as peripheral neuropathy. γ-Tubulin is a possible target as antitumor drugs with low side effects, but the antitumor effect of γ-tubulin inhibitors has not been reported yet. In this study, we verified the antitumor activity of gatastatin, a γ-tubulin specific inhibitor.

A novel translation inhibitor, mersicarpine, inhibits S-phase progression and induces apoptosis in HL60 cells.

Mersicarpine is an aspidosperma alkaloid isolated from the Kopsia genus of plants. Its intriguing structural features have attracted much attention in synthetic organic chemistry, but no biological activity has been reported. Here, we report the effects of mersicarpine on human leukemia cell line HL60.

Structural Revision of Natural Cyclic Depsipeptide MA026 Established by Total Synthesis and Biosynthetic Gene Cluster Analysis.

A revised structure of natural 14-mer cyclic depsipeptide MA026, isolated from Pseudomonas sp. RtlB026 in 2002 was established by physicochemical analysis with HPLC, MS/MS, and NMR and confirmed by total solid-phase synthesis. The revised structure differs from that previously reported in that two amino acid residues, assigned in error, have been replaced.

Structure Optimization of Gatastatin for the Development of γ-Tubulin-Specific Inhibitor.

Gatastatin ( -benzyl glaziovianin A) is a γ-tubulin-specific inhibitor that is used to investigate γ-tubulin function in cells. We have previously reported that the unsubstituted phenyl ring of the -benzyl group in gatastatin is important for γ-tubulin inhibition. To obtain further structural information regarding γ-tubulin inhibition, we synthesized several gatastatin derivatives containing a fixed -benzyl moiety.

Non-electrophilic TRPA1 agonists, menthol, carvacrol and clotrimazole, open epithelial tight junctions via TRPA1 activation.

Activation of the transient receptor potential A1 channel (TRPA1) by electrophilic agonists was reported to induce the opening of tight junctions (TJs). Because compounds that increase TJ permeability can be paracellular permeability enhancers, we investigated the effect of non-electrophilic TRPA1 activators, including food ingredients (menthol and carvacrol) and medication (clotrimazole), on epithelial permeability. We show that all three compounds induced increase of the permeability of fluorescein isothiocyanate-conjugated dextran (4 kDa) and decrease of transepithelial electrical resistance, accompanied by Ca2+ influx and cofilin activation in epithelial MDCK II monolayers.

Transient receptor potential V4 channel stimulation induces reversible epithelial cell permeability in MDCK cell monolayers.

The transient receptor potential V4 channel (TRPV4) is responsive to a variety of physical and chemical stimuli, including a synthetic agonist GSK1016790A (GSK). Here, we show that TRPV4 is functionally expressed in, and that GSK induces the reversible opening of tight junctions (TJs) in epithelial Madin-Darby canine kidney II monolayers. Stimulation of TRPV4 by GSK induces an increase in fluorescein isothiocyanate-conjugated dextran (4 kDa) permeability and a reduction in transepithelial resistance, and these responses are blocked by pretreatment with the specific TRPV4 antagonist.

TRPA1-dependent reversible opening of tight junction by natural compounds with an α,β-unsaturated moiety and capsaicin.

The delivery of hydrophilic macromolecules runs into difficulties such as penetration of the cell membrane lipid bilayer. Our prior experiment demonstrated that capsaicin induces the reversible opening of tight junctions (TJs) and enhances the delivery of hydrophilic macromolecules through a paracellular route. Herein, we screened paracellular permeability enhancers other than capsaicin.

MA026, an anti-hepatitis C virus compound, opens tight junctions of the epithelial cell membrane.

MA026 is an antiviral natural compound against hepatitis C virus (HCV). It was recently reported that MA026 binds claudin-1 (CLDN1) and inhibits HCV infection. Although CLDN1 is an important component of tight junctions (TJ) in the epithelial cell layer, the effects of MA026 on the TJ barrier function remained to be revealed.

Eudistomin C, an Antitumor and Antiviral Natural Product, Targets 40S Ribosome and Inhibits Protein Translation.

Eudistomin C (EudiC), a natural product, shows potent antitumor and antiviral activities, but the target molecule and the mechanism of action remain to be revealed. Here, we show that the 40S ribosome is the target in EudiC cytotoxicity. We isolated EudiC-resistant mutants from a multidrug-sensitive yeast strain, and a genetic analysis classified these YER (yeast EudiC resistance) mutants into three complementation groups.

Tetrandrine induces lipid accumulation through blockade of autophagy in a hepatic stellate cell line.

Macroautophagy, or autophagy, is a cellular response in which unnecessary cytoplasmic components, including lipids and organelles, are self-degraded. Recent studies closely related autophagy to activation of hepatic stellate cells (HSCs), a process critical in the pathogenesis of liver fibrosis. During HSC activation, cytoplasmic lipid droplets (LDs) are degraded as autophagic cargo, and then cells express fibrogenic genes.

Vicenistatin induces early endosome-derived vacuole formation in mammalian cells.

Homotypic fusion of early endosomes is important for efficient protein trafficking and sorting. The key controller of this process is Rab5 which regulates several effectors and PtdInsPs levels, but whose mechanisms are largely unknown. Here, we report that vicenistatin, a natural product, enhanced homotypic fusion of early endosomes and induced the formation of large vacuole-like structures in mammalian cells.

Total Synthesis and Biological Evaluation of Irciniastatin A (a.k.a. Psymberin) and Irciniastatin B.

Irciniastatin A (a.k.a.

Increased CD112 expression in methylcholanthrene-induced tumors in CD155-deficient mice.

Tumor recognition by immune effector cells is mediated by antigen receptors and a variety of adhesion and costimulatory molecules. The evidence accumulated since the identification of CD155 and CD112 as ligands for DNAM-1 in humans and mice has suggested that the interactions between DNAM-1 and its ligands play an important role in T cell- and natural killer (NK) cell-mediated recognition and lysis of tumor cells. We have previously demonstrated that methylcholanthrane (MCA) accelerates tumor development in DNAM-1-deficient mice, and the Cd155 level on MCA-induced tumors is significantly higher in DNAM-1-deficient mice than in wild-type (WT) mice.

Terpendole E and its derivative inhibit STLC- and GSK-1-resistant Eg5.

Terpendole E is first natural product found to inhibit mitotic kinesin Eg5, but its inhibitory mechanism remains to be revealed. Here, we report the effects of terpendole E and 11ketopaspaline (a new natural terpendole E analogue) on the Eg5-microtubule interaction and in several Eg5 mutants. 11-Ketopaspaline is a shunt product from terpendole E, and it shows potent inhibitory activity against the microtubule-stimulated ATPase activity of Eg5.

The reversible increase in tight junction permeability induced by capsaicin is mediated via cofilin-actin cytoskeletal dynamics and decreased level of occludin.

Previous results demonstrated that capsaicin induces the reversible tight junctions (TJ) opening via cofilin activation. The present study investigated the mechanisms underlying the reversible TJ opening and compared the effect to the irreversible opening induced by actin inhibitors. Capsaicin treatment induced the F-actin alteration unique to capsaicin compared to actin-interacting agents such as latrunculin A, which opens TJ irreversibly.

Glaziovianin A prevents endosome maturation via inhibiting microtubule dynamics.

Glaziovianin A, an isoflavone isolated from the leaves of Ateleia glazioviana, inhibits the cell cycle progression in M-phase with an abnormal spindle structure, but its inhibitory mechanism has not been revealed. Here, we report that glaziovianin A and its derivatives are microtubule dynamics inhibitors. Glaziovianin A extended the time lag of tubulin polymerization without changing the net amount of polymerized tubulin in vitro and suppressed microtubule dynamics in cells.

Construction of multidrug-sensitive yeast with high sporulation efficiency.

Budding yeast is often used in chemical genetics for screening, target identification, and compound verification, but its high-level drug resistance has made the analysis of compounds difficult. Here we report the construction of 12geneΔ0HSR, a strain that lacks eight efflux pumps located on the plasma membrane and four transcription factors involved in expression of efflux pumps, and contains the RME1(ins-308A) mutation. This strain retained sufficient transformation, mating, and sporulation efficiency for genetic analysis in addition to hypersensitivity against several compounds.

Trastuzumab and pertuzumab produce changes in morphology and estrogen receptor signaling in ovarian cancer xenografts revealing new treatment strategies.

Purpose: The aim of this study was to investigate the antitumor effects of HER2-directed combination therapy in ovarian cancer xenograft models to evaluate their potential. The combinations of trastuzumab and pertuzumab, and trastuzumab and aromatase inhibitor therapy were investigated.

Experimental Design: The effects of trastuzumab, pertuzumab, and letrozole on growth response, apoptosis, morphology, and gene and protein expression were evaluated in the SKOV3 ovarian cancer cell line xenograft and a panel of five human ovarian xenografts derived directly from clinical specimens.

Irciniastatin A induces JNK activation that is involved in caspase-8-dependent apoptosis via the mitochondrial pathway.

Irciniastatin A (ISA)/psymberin, a pederin-type natural product isolated from marine sponge, exhibits extremely potent and selective cytotoxicity against certain human cancer cell lines, but its molecular target and cytotoxic mechanisms are still unknown. Here we show that ISA is a potent inhibitor of protein translation, and induces apoptosis accompanied with activation of the stress-activated protein kinases via the mitochondrial pathway in human leukemia Jurkat cells. ISA potently inhibited protein translation, and induced a slow but prolonged activation of the stress-activated protein kinases, JNK and p38, at between 1h and 6h after treatment.