Published papers

作用機構の異なる種々の制癌剤が共通してカスパーゼ３の活性化、NADPH oxidaseの活性化に伴う過酸化水素の生成という過程をへて、アポトーシスを誘導することを報告した。(8ページ)

イノスタマイシンが小細胞肺癌細胞に対して、タキソールの殺細胞効果を増強することを報告した。(7ページ)

新規ホスホリパーゼＣ阻害剤フォリペプチンの構造決定について報告した。(6ページ)

ホスファチジルイノシトールキナーゼ阻害物質の探索方法を開発し、報告した。(3ページ)

新規インドールアルカロイド化合物ペンドールマイシンの細胞に対する影響を報告した。(4ページ)

新規制癌物質バルミノマイシンIとIIを単離し、それらの制癌活性を報告した。(5ページ)

新規制癌物質サクワヤマイシンを単離し、それらの制癌活性を報告した。(4ページ)

新規制癌物質セリルビシンおよび1-ヒドロキシセリルビシンを単離し、それらの制癌活性を報告した。(4ページ)

A new compound, MK800-62F1, was isolated from a cultured broth of Streptomyces diastatochromogenes MK800-62F1. It inhibited H2O2-induced apoptosis in human small cell lung carcinoma Ms-1 cells as well as in human T-cell leukemia Jurkat cells. In addition, MK800-62F1 also inhibited camptothecin-induced apoptosis in Jurkat cells, which was mediated by intracellular H2O2 generation. MK800-62F1 did not exhibit antioxidative activity in vitro, suggesting that inhibition of apoptosis by MK800-62F1 was not due to the scavenging of H2O2, rather it was due to the modulation of the downstream event of H2O2 generation.

Here, we show that mesenchyme cells have a novel morphogenetic function in epithelial cell proliferation in starfish embryos. Blastula embryos were injected with pure populations of mesenchyme cells and the total cell numbers in the treated embryos were subsequently determined at different developmental stages. When a total of 40-50 mesenchyme cells was injected, total cells numbers in mid-gastrula embryos and 3-day-old bipinnaria larvae increased significantly (by 1.3-fold) compared with controls, with no indication of any mitotic activity in the injected mesenchyme cells. However, injection of more than 150 mesenchyme cells failed to induce proliferation of the epithelial cells and, moreover, interfered with normal morphogenesis. These developmental abnormalities occurred concomitantly with a severe condensation of the fibrous component of the extracellular matrix. Our data suggest that epithelial cell proliferation is induced by an appropriate number of mesenchyme cells in concert with the fibrous component of the extracellular matrix. © 2010 Wiley-Liss, Inc.

Identifying the targets of bioactive compounds is a major challenge in chemical biological research. Here, we identified the functional target of the natural bioactive compound glucopiericidin A (GPA) through metabolomic analysis. We isolated GPA while screening microbial samples for a filopodia protrusion inhibitor. Interestingly, GPA alone did not inhibit filopodia protrusion, but synergistically inhibit protrusion with the mitochondrial respiration inhibitor, piericidin A (PA). These results suggested that GPA might inhibit glycolysis. Capillary electrophoresis time-of-flight mass spectrometry (CE-TOFMS) provided strong evidence that GPA suppresses glycolysis by functionally targeting the glucose transporter. GPA may therefore serve as a glucose transporter chemical probe. Simultaneous inhibition of both glycolysis and mitochondrial respiration dramatically decreased intracellular ATP levels, indicating that GPA inhibits ATP-dependent filopodia protrusion with PA. Our results represent a challenge of molecular target identification using metabolomic analysis. © 2010 Elsevier Ltd. All rights reserved.

Metabolomics is defined as the quantitative measurement of the dynamic multiparametric metabolites. Recent technological advances in the quantification of cellular metabolites, such as capillary electrophoresis (CE) -TOFMS, have prompted the comprehensive analysis of the global metabolism. Now, metabolomics has been used in the identification of new biomarker for toxicology and disease diagnosis, and the elucidation of fermentation processes. Moreover, it is considered that metabolomics would be a powerful tool for the target identification of small molecular bioactive compounds. Here we introduce our recent study that metabolomics was applied to identify the molecular target of glucopiericidin A, which was isolated through a screening of natural products for an inhibitor of cellular filopodia protrusion in carcinoma cells.

A new compound, migrastatin, was isolated from a cultured broth of Streptomyces sp. MK929-43F1, as an inhibitor of tumor cell migration. It was purified by column chromatographies on silica gel and Sephadex LH-20 and HPLC. Migrastatin has the molecular formula of C27H39NO7 consisting of 14-membered macrolide and glutarimide moiety. It inhibited spontaneous migration of human esophageal cancer EC17 cells. Migration inhibitory activity of migrastatin was not dependent on cytotoxicity or inhibition of protein synthesis.

A new compound, MK800-62F1, was isolated from a cultured broth of Streptomyces diastatochromogenes MK800-62F1. The structure was determined by NMR analysis and degradation experiments.

2-Phenylquinoline (1) degraded proteins under photo-irradiation with long-wavelength UV light without additives and under neutral conditions. We designed and synthesized a 2-phenylquinoline-estrogen receptor-α (ER-α) agonist (hybrid 2) and a 2-phenylquinoline-ER-α antagonist (hybrid 3) containing estradiol and 4-hydroxytamoxifen moieties, respectively. These 2-phenylquinoline hybrids effectively and selectively photo-degraded the target transcription factor, ER-α, which has a high affinity for estradiol and 4-hydroxytamoxifen. Target-selective photo-degradation was examined in both glass vessels and MCF-7 breast cancer cells, which are dependent upon ER-α for growth. In addition, 2-phenylquinoline-estradiol hybrid 2 functioned as an agonist of ER-α and promoted growth of MCF-7 in the absence of photo-irradiation, while it inhibited the growth of MCF-7 cells upon photo-irradiation due to the photo-degradation of ER-α. In contrast, 2-phenylquinoline-4-hydroxytamoxifen hybrid 3 inhibited growth of MCF-7 cells in the absence of photo-irradiation due to the antagonist effect of the 4-hydroxytamoxifen moiety against ER-α, and upon photo-irradiation significantly inhibited cell growth due to the dual antagonist effect of the 4-hydroxytamoxifen moiety and photo-degradation of ER-α. © 2011 The Royal Society of Chemistry.

Viral protein R (Vpr), one of the accessory gene products of human immunodeficiency virus type 1 (HIV-1), is responsible for the incorporation of a viral genome into the nucleus upon infection. Vpr also arrests the cell cycle and induces apoptosis in infected cells. Similarly, in yeast, Vpr localizes in the nucleus and shows growth inhibitory activity; however, the molecular mechanism of growth inhibition remains unknown. To elucidate this mechanism, several point mutations of Vpr, which are known to perturb several phenotypes of Vpr in mammalian cells, were introduced in the budding yeast, Saccharomyces cerevisiae. For the first time, we found that growth inhibition by Vpr occurred independently of intracellular localization in yeast, as has previously been reported in mammals. We also indentified several amino acid residues, the mutation of which cancels growth inhibitory activity, and/or alters localization, both in yeast and mammalian cells, suggesting the importance of these residues for the phenotypes. Copyright © 2005 by The Microbiology Research Foundation.

Pro-inflammatory cytokines, such as tumor necrosis factor (TNF)-α and interleukin-1α (IL-1α), trigger the activation of the transcription factor nuclear factor-B, a molecule that induces the expression of a variety of genes, including intercellular adhesion molecule-1 (ICAM-1). Here, we report that mycotrienin II, a member of the triene-ansamycin group, inhibited the cell-surface ICAM-1 expression induced by TNF-α more strongly than that induced by IL-1α in human lung carcinoma A549 cells. Mycotrienin II was found to inhibit protein synthesis in intact living cells, as well as in cell-free translation systems. Among translation inhibitors tested, acetoxycycloheximide and anisomycin, but neither puromycin nor emetine, inhibited the TNF-α-induced ICAM-1 expression at lower concentrations than the IL-1α-induced ICAM-1 expression. Several compounds of the triene-ansamycin group (that is, mycotrienin I, trienomycin A, trierixin, quinotrierixin and quinotrierixin HQ) also inhibited ICAM-1 expression, as well as cell-free translation in a manner similar to mycotrienin II. These results indicate that mycotrienin II is a direct inhibitor of translation, thereby inhibiting ICAM-1 expression induced by pro-inflammatory cytokines. © 2011 Japan Antibiotics Research Association. All rights reserved.

Aim Hepatic fibrosis and angiogenesis occur in parallel during the progression of liver disease. Fibrosis promotes angiogenesis via inducing vascular endothelial growth factor (VEGF) from the activated hepatic stellate cells (HSCs). In turn, increased neovessel formation causes fibrosis, although the underlying molecular mechanism remains undetermined. In the current study, we aimed to address a role of endothelial cells (ECs) as a source of latent transforming growth factor (TGF)-β, the precursor of the most fibrogenic cytokine TGF-β. Methods After recombinant VEGF was administered to mice via the tail vein, hepatic angiogenesis and fibrogenesis were evaluated using immunohistochemical and biochemical analyses in addition to investigation of TGF-β activation using primary cultured HSCs and liver sinusoidal ECs (LSECs). Results In addition to increased hepatic levels of CD31 expression, VEGF-treated mice showed increased α-smooth muscle actin (α-SMA) expression, hepatic contents of hydroxyproline, and latency associated protein degradation products, which reflects cell surface activation of TGF-β via plasma kallikrein (PLK). Liberating the PLK-urokinase plasminogen activator receptor complex from the HSC surface by cleaving a tethering phosphatidylinositol linker with its specific phospholipase C inhibited the activating latent TGF-β present in LSEC conditioned medium and subsequent HSC activation. Conclusion Neovessel formation (angiogenesis) accelerates liver fibrosis at least in part via provision of latent TGF-β that activated on the surface of HSCs by PLK, thereby resultant active TGF-β stimulates the activation of HSCs. © 2013 Elsevier Inc. All rights reserved.