The asymmetric total synthesis of (+)-panepophenanthrin, an inhibitor of ubiquitin-activating enzyme (E1), has been accomplished using catalytic asymmetric alpha aminoxylation of 1,4-cyclohexanedione monoethylene ketal as a key step, followed by several diastereoselective reactions. The biomimetic Diels-Alder reaction of a monomer precursor was found to proceed efficiently in water. The investigation of the biological properties of new derivatives of (+)-panepophenanthrin enabled us to develop new cell-permeable E1 inhibitors, RKTS-80, -81, and -82.

We isolated a novel unique pentaketide dimer designated as epoxytwinol A from the fermentation broth of a fungus. The structure of epoxytwinol A was determined to have a new carbon skeleton with C(2) symmetry by elucidation of spectroscopic evidence. Epoxytwinol A inhibited endothelial cell migration stimulated by vascular endothelial growth factor (ED(100)= 2.6 microM).

[reaction: see text] The first asymmetric total synthesis of EI-1941-1, -2, and -3, inhibitors of the interleukin-1beta converting enzyme (ICE), has been accomplished, starting from a chiral epoxy iodoquinone 11, a key intermediate in our total synthesis of epoxyquinols A and B. Despite a failure to synthesize the inhibitors by our postulated biosynthetic route, we were able to diastereoselectively synthesize them via an intramolecular carboxypalladation with the key steps being a 6-endo cyclization mode followed by beta-hydride elimination. The investigation of the biological properties of EI-1941-1, -2, and -3 and their derivatives disclosed them to be potent and effective ICE inhibitors with less cytotoxicity than EI-1941-1 and -2 in a cultured cell system.

We found that a fungus Neosartorya sp. produced an angiogenesis inhibitor, RK-805. By spectroscopic analyses and semi-synthetic methods from fumagillin, the structure of RK-805 was identified as 6-oxo-6-deoxyfumagillol, which has not been reported as a natural product. RK-805 preferentially inhibited the growth of human umbilical vein endothelial cells (HUVECs) rather than that of human normal fibroblast in cell proliferation assays and blocked endothelial cell migration induced by vascular endothelial growth factor (VEGF). Moreover, RK-805 selectively inhibited methionine aminopeptidase-2 (MetAP2), but not methionine aminopeptidase-1 (MetAP1). The docked structure of RK-805 complexed with human MetAP2 indicated that not only a covalent bond between a nucleophilic imidazole nitrogen atom of His231 and the carbon of the reactive spirocyclic epoxide of RK-805, but also a hydrogen bond between NH (Asn329) and the carbonyl group of RK-805 at C-6 promote close contact in the binding pocket of the enzyme. Taken together, these results suggest that structure activity relationships of RK-805 derivatives at both C-4 and C-6, in comparison with ovalicin and TNP-470, would be useful for development of new angiogenesis inhibitors.

[structure: see text] Azaspirene isolated from the fungus Neosartorya sp. is a novel angiogenesis inhibitor with a 1-oxa-7-azaspiro[4.4]non-2-ene-4,6-dione skeleton. Azaspirene inhibits the endothelial migration induced by vascular endothelial growth factor (ED100 = 27.1 microM).

AbstractFor Abstract see ChemInform Abstract in Full Text.

A unique pentaketide dimer structure of a novel fungal metabolite with antiangiogenic activity, designated as epoxyquinol A (1), was determined on the basis of NMR spectral data as well as the X-ray crystallographic analysis. 1 inhibits the endothelial migration induced by vascular endothelial growth factor (ED100 = 3 mug/mL).

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Angiogenesis is an essential event in a variety of physiological and pathological processes. Therefore, effective inhibition of this event is a promising strategy for treating angiogenesis-related diseases, including cancer. The current study investigated two unique bafilomycin-type macrolide inhibitors of angiogenesis, PC-766B' (1) and PC-766B (2). The strain RK97-56 which produced the inhibitors was identified as Nocardia sp. by chemotaxonomic analyses, and the purification of the inhibitors was guided by their anti-angiogenic activities. PC-766B' (1) and PC-766B (2) exhibited potent inhibitory activities towards endothelial cell migration stimulated by the vascular endothelial growth factor (VEGF).

Zearalenones are mycotoxins with estrogenic activity consisting of a resorcinol moiety fused to a 14-membered macrocyclic lactone and are produced by various Fusarium species. We found that Clonostachys rosea IFO 7063 was effectively capable of converting zearalenone (1) to cleavage product (2), 1-(3,5-dihydroxyphenyl)-10'-hydroxy-1'E-undecene-6'-one. Moreover, cleavage product 2 did not show potent estrogenic activity like that of 1 and 17beta-estradiol in the human breast cancer MCF-7 cell proliferation assay.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

A new cell growth inhibitor, curvularol, was isolated from the fermentation broth of Curvularia sp. RK97-F166. Curvularol showed no antibacterial activity, and very weak antifungal activity. However, curvularol inhibited the cell cycle progression of normal rat kidney (NRK) cells in G1 phase at 150 ng/ml. Curvularol induced the morphological reversion of srcts-transformed NRK cells at 100 ng/ml, and inhibited protein synthesis same as cycloheximide.

We found that antitumor drugs such as cytotrienin A, camptothecin, taxol, and 5-fluorouracil induced the activation of a 36-kDa protein kinase (p36 myelin basic protein (MBP) kinase) during apoptosis in human promyelocytic leukemia HL-60 cells. This p36 MBP kinase, which phosphorylates MBP in an in-gel kinase assay, results from the caspase-3-mediated proteolytic cleavage of MST/Krs protein, a mammalian Ste20-like serine/threonine kinase. Herein the correlation between cytotrienin A-induced apoptosis and the activation of MST/Krs proteins was examined in human tumor cell lines, including leukemia-, lung-, epidermoid-, cervix-, stomach-, and brain-derived cell lines. In cytotrienin A-sensitive cell lines, we observed a strong activation of p36 MBP kinase by cleavage of the C-terminal regulatory domain of full-length MST/Krs proteins by caspase-3. When the kinase-inactive mutant form of MST/Krs protein was overexpressed in cytotrienin A-sensitive HL-60 cells, the cytotrienin A-induced apoptosis was partially inhibited. Because cytotrienin A also activated c-Jun N-terminal kinase, we examined the effect of the expression of dominant negative c-Jun on cytotrienin A-induced apoptosis. The expression of dominant negative c-Jun also partially inhibited cytotrienin A-induced apoptosis. Furthermore, coexpression of kinase-inactive MST/Krs protein and dominant negative c-Jun completely suppressed cytotrienin A-induced apoptosis. These findings suggest that the proteolytic activation of MST/Krs and c-Jun N-terminal kinase activation are involved in cytotrienin A-induced apoptosis in human tumor cell lines.

Annals of the New York Academy of SciencesVolume 886, Issue 1 p. 273-275 Activation of a 36-kD MBP Kinase, an Active Proteolytic Fragment of MST/Krs Proteins, during Anticancer Drug-Induced Apoptosis HIDEAKI KAKEYA, HIDEAKI KAKEYA Antibiotics Laboratory, The Institute of Physical and Chemical Research (RIKEN), 2–1 Hirosawa, Wako-shi, Saitama 351–0198, JapanSearch for more papers by this authorRIE ONOSE, RIE ONOSE Antibiotics Laboratory, The Institute of Physical and Chemical Research (RIKEN), 2–1 Hirosawa, Wako-shi, Saitama 351–0198, JapanSearch for more papers by this authorHIROYUKI OSADA, Corresponding Author HIROYUKI OSADA Antibiotics Laboratory, The Institute of Physical and Chemical Research (RIKEN), 2–1 Hirosawa, Wako-shi, Saitama 351–0198, Japan To whom correspondence should be addressed. Phone, +81-48-467-9541; fax, +81-48-462-4669. e-mail, [email protected]Search for more papers by this author HIDEAKI KAKEYA, HIDEAKI KAKEYA Antibiotics Laboratory, The Institute of Physical and Chemical Research (RIKEN), 2–1 Hirosawa, Wako-shi, Saitama 351–0198, JapanSearch for more papers by this authorRIE ONOSE, RIE ONOSE Antibiotics Laboratory, The Institute of Physical and Chemical Research (RIKEN), 2–1 Hirosawa, Wako-shi, Saitama 351–0198, JapanSearch for more papers by this authorHIROYUKI OSADA, Corresponding Author HIROYUKI OSADA Antibiotics Laboratory, The Institute of Physical and Chemical Research (RIKEN), 2–1 Hirosawa, Wako-shi, Saitama 351–0198, Japan To whom correspondence should be addressed. Phone, +81-48-467-9541; fax, +81-48-462-4669. e-mail, [email protected]Search for more papers by this author First published: 06 February 2006 https://doi.org/10.1111/j.1749-6632.1999.tb09434.xCitations: 7Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onEmailFacebookTwitterLinkedInRedditWechat REFERENCES 1 Nagata, S. 1997. Apoptosis by death factor. Cell 88: 355–365. 10.1016/S0092-8674(00)81874-7 CASPubMedWeb of Science®Google Scholar 2 Nicholson, D.W. et al. 1997. Caspases: Killer proteases. Trends Biochem. Sci. 22: 299–306. 10.1016/S0968-0004(97)01085-2 CASPubMedWeb of Science®Google Scholar 3 Kakeya, H. et al. 1997. Cytotrienin A, a novel apoptosis inducer in human leukemia HL-60 cells. J. Antibiot. 50: 370–372. 10.7164/antibiotics.50.370 CASPubMedWeb of Science®Google Scholar 4 Zhang, H.-P. et al. 1997. Novel Triene-ansamycins, cytotrienins A and B inducing apoptosis on human leukaemia HL-60 Cells. Tetrahedron Lett. 38: 1789–1792. 10.1016/S0040-4039(97)00170-6 CASWeb of Science®Google Scholar 5 Creasy, C.L. et al. 1995. Cloning and characterization of a human protein kinase with homology to Ste20. J. Biol. Chem. 270: 21695–21700. 10.1074/jbc.270.37.21695 CASPubMedWeb of Science®Google Scholar 6 Creasy, C.L. et al. 1996. The Ste20-like protein kinase, Mst1, dimerizes and contains an inhibitory domain. J. Biol. Chem. 271: 21049–21053. 10.1074/jbc.271.35.21049 CASPubMedWeb of Science®Google Scholar 7 Taylor, L.K. et al. 1996. Newly identified stress-responsive protein kinases, Krs-1 and Krs-2. Proc. Natl. Acad. Sci. USA 93: 10099–10104. 10.1073/pnas.93.19.10099 CASPubMedWeb of Science®Google Scholar 8 Kakeya, H. et al. 1997. Neuritogenic effect of epolactaene derivatives on human neuroblastoma cells which lack high-affinity nerve growth factors. J. Med. Chem. 40: 391–394. 10.1021/jm960719a CASPubMedWeb of Science®Google Scholar 9 Watabe, M. et al. 1999. Requirement of protein kinase (Krs/MST) activation for MT-21-induced apoptosis. Oncogene 18: 5211–5220. 10.1038/sj.onc.1202901 CASPubMedWeb of Science®Google Scholar 10 Graves, J. D. et al. 1998. Caspase-mediated activation and identification of apoptosis by the mammalian Ste20-like kinase Mst1. EMBO J. 17: 2224–2234. 10.1093/emboj/17.8.2224 CASPubMedWeb of Science®Google Scholar 11 Lee, K.-K. et al. 1998. Proteolytic activation of MST/Krs, STE-20-related protein kinase, by caspase during apoptosis. Oncogene 16: 3029–3037. 10.1038/sj.onc.1201840 CASPubMedWeb of Science®Google Scholar 12 Kakeya, H. et al. 1998. Caspase-mediated activation of a p36 myelin basic protein kinase during anticancer drug-induced apoptosis. Cancer Res. 58: 4888–4894. CASPubMedWeb of Science®Google Scholar Citing Literature Volume886, Issue1ANTICANCER MOLECULES: STRUCTURE, FUNCTION, AND DESIGNDecember 1999Pages 273-275 ReferencesRelatedInformation

In this report, we studied the effect of phosmidosine, a proline-containing nucleotide on the serum-induced cell cycle progression in human lung fibroblast WI-38 cells. Phosmidosine suppressed S-phase entry and arrested cell cycle progression at the G1 phase. In serum-stimulated cells, phosmidosine did not affect the activation of the mitogen-activated protein kinase cascade. However, phosmidosine inhibited hyperphosphorylation of retinoblastoma (RB) protein by RB-kinases such as cyclin-dependent kinase 4 and cyclin-dependent kinase 2, probably as a result of the inhibition of cyclin D1 expression. Furthermore, in tsFT210 cells, a temperature-sensitive cdc2 mutant isolated from the mouse mammary carcinoma cell line FM3A, phosmidosine, irreversibly inhibited the cell cycle progression at G1 without affecting the G2 to M transition. Phosmidosine acts at an earlier point in G1 compared with mimosine or aphidicolin, well-known cell cycle blockers at the G1-S boundary. Taken together, phosmidosine arrested cells at a specific point between the start point and restriction point in G1 and is a useful drug that may contribute to the understanding of the regulatory mechanisms of G1 progression.

A novel anticancer drug, cytotrienin A, isolated from Streptomyces sp., induces apoptosis (or programmed cell death) in human promyelocytic leukemia HL-60 cells within 4 h. To elucidate the mechanism of this process, we performed an in-gel kinase assay using myelin basic protein (MBP) as a substrate and found the activation of kinase with an apparent molecular mass of 36 kDa (p36 MBP kinase). The dose of cytotrienin A required to activate p36 MBP kinase was consistent with that required to induce apoptotic DNA fragmentation in HL-60 cells. This p36 MBP kinase was activated with kinetics distinct from the activation of JNK (c-Jun N-terminal kinase)/stress-activated protein kinase and p38 MAPK (mitogen-activated protein kinase). Importantly, the p36 MBP kinase was immunologically different from MAPK superfamily molecules such as ERK1, JNK isoforms, and p38 MAPK. In addition, the p36 MBP kinase activation and apoptotic DNA fragmentation were inhibited by antioxidants such as N-acetylcysteine and reduced-form glutathione. The p36 MBP kinase activation was also observed during hydrogen peroxide (H2O2) and okadaic acid-induced apoptosis. Although a specific inhibitor of caspase-3-like proteases (Ac-DEVD-CHO) or a specific inhibitor of caspase-1-like proteases (Ac-YVAD-CHO) did not block the cytotrienin A-, H2O2-, or okadaic acid-induced apoptosis, a broad specificity inhibitor of caspases (Z-Asp-CH2-DCB) strongly inhibited the apoptosis of HL-60 cells. Surprisingly, Z-Asp-CH2-DCB inhibited the activation of p36 MBP kinase induced by cytotrienin A or H2O2, but did not inhibit the activation of JNK/stress-activated protein kinase and p38 MAPK. Taken together, these results indicate that p36 MBP kinase activation is downstream of the activation of Z-Asp-CH2-DCB-sensitive caspases, and reactive oxygen species could be included in the apoptotic events. Moreover, according to the Western blotting using the antibodies against MST1/Krs2 or MST2/Krs1, it is suggested that the p36 MBP kinase is an active proteolytic product of MST1/Krs2 and MST2/Krs1, which are originally cloned by virtue of its homology to the budding yeast Ste20 kinase. Thus, the p36 MBP kinase might be a common component of the diverse signaling pathways leading to apoptosis, and controlling this p36 MBP kinase pathway might be a novel strategy for cancer chemotherapy.

We have established a bioassay system using a mouse cdc2 mutant cell line, tsFT210, to detect inhibitors of the mammalian cell cycle. When cultured at the high temperature, restrictive temperature at 39.4 degrees C, tsFT210 cells can be arrested at G2 phase and are large in size. Four hours after release from G2 arrest, the cells entered into the G1 phase. At this time, G1 phase cells were easily discriminated from the G2/M-cells by their size under microscopic observation. The cell-morphology-based bioassay utilizing tsFT210 cells is very simple and sensitive for detecting cdc2 kinase inhibitors and also G2/M-phase inhibitors of the mammalian cell cycle. To demonstrate the merits of this bioassay, the effects of protein kinase inhibitors isolated from actinomycetes were investigated. RK-286C and RK-1409, which are structurally related to staurosporine, inhibited cell cycle progression at the G2 phase in both G2-synchronized and nonsynchronized cultures of tsFT210 cells. Another kinase inhibitor, sangivamycin, inhibited cell cycle progression at the G2 phase of cells released from temperature arrest but did not inhibit that of the exponentially growing cells. Using the bioassay system, we carried out screening of the cell cycle inhibitors from the microbial metabolites and have discovered several new inhibitors, including novel compounds such as tryprostatins A, B and acetophthalidin. Thus, this bioassay allowed for the detection of cell cycle inhibitors and provided a convenient and useful method for the screening of new inhibitors from the microbial metabolites.

This report describes the biological effects of our original compound, Ki6783 ((3,4-dimethoxy)-4-phenoxy-6,7-dimethoxyquinoline), a potent and selective inhibitor of platelet-derived growth factor (PDGF) receptor autophosphorylation. This compound strongly inhibited autophosphorylation of the PDGF β-receptor in cultured rat glomerular mesangial cells (MC) bearing this receptor (IC500.1 μM), although it did not inhibit autophosphorylation of other growth factor receptors even at 100 μM.In a cell-free kinase experiment, it showed selective inhibition of PDGF β-receptor tyrosine kinase. A kinetic study of the compound to this tyrosine kinase revealed a competitive mode of action to ATP. [3H]Thymidine incorporation and cell proliferation of MC were inhibited by Ki6783 in a dose-dependent manner after Ki6783 and PDGF-BB were added to the culture medium. Furthermore, this compound normalized the fibrotic cell shape of v-sis-transformed NIH3T3 cells, which grow in an autocrine manner via the PDGF receptor. These effects could be explained by the inhibition of intracellular signal transduction triggered by PDGF receptor autophosphorylation, in which activation of mitogen-activated protein kinase occurs. These results suggest that Ki6783 is one of the more potent and selective inhibitors of PDGF receptor autophosphorylation and that it may be useful in ameliorating cell abnormalities due to excess action of PDGF and its receptor systems in several diseases.

response to various physiological or pathological stimuli. Apoptosis is involved in embryonic development, tissue remodeling, and tumor regression. Autoreactive T cells are selectively depleted by apoptosis during clonal selection in the immune system.2 ~4) Recently, it has been shownthat the efficacy of various anticancer agents is dependent on the intrinsic propensity of the target cells whether if the cells respond to the anticancer agents by apoptosis or not. In fact, apoptosis is induced by various anticancer agents such as cisplatin5), camptothecin6), etoposide7), and taxol8). The compounds which induced apoptosis in tumor cells might be a good candidate for anticancer drugs. From this point of view, we started to explore new apoptosis inducers derived from microorganisms by utilizing a human promyelocytic leukaemia cell line, HL-60 as an indicator ofapoptosis. In the course of our screening, we found that an actinomycete strain RK95-74 isolated from a soil sample collected in Shiki City, Saitama Prefecture, Japan, produced a new potent apoptosis inducer, cytotrienin A (1) containing a trieneansamycin, a 1-aminocyclopropane carboxylic acid and a 1-cyclohexene-l-carboxylic acid moieties. (Fig. 1). The strain RK95-74 was identified to be Streptomyces sp. and deposited in the National Institute of Bioscience APR. 1997