ognizant Communication Corporation



Oncology Research, Volume 13, pp. 513-520
0965-0407/03 $20.00 + .00
Copyright © 2003 Cognizant Comm. Corp.
Printed in the USA. All rights reserved.

Understanding the Selectivity of Fumagillin for the Methionine Aminopeptidase Type II

Christian D. P. Klein1 and G. Folkers2

1Pharmaceutical and Medicinal Chemistry, University of the Saarland FR 8.5, P.O. Box 151150, D-66111 Saarbruecken, Germany
2Pharmaceutical Chemistry, Department of Applied Biosciences, ETH Zürich, Winterthurerstr. 190, CH-8056 Zürich, Switzerland

The aim of this study is to explain the selectivity of the antiangiogenic drug fumagillin for the eukaryotic enzyme methionine aminopeptidase type II (MetAP-II, EC over the structurally very similar MetAP-I. A homology model for the human MetAP-I is constructed and molecular dynamics simulations are performed on this model with and without a docked fumagillin molecule. These simulations are compared with analogous simulations that were performed on the experimentally determined structure of the human MetAP-II enzyme. We observe an increased flexibility of the active site histidine that is covalently modified by fumagillin in the MetAP-I enzyme. The MetAP-I active site residues, particularly the fumagillin-binding histidine, have a lower probability to be in a conformation that is prone to react with the drug than their MetAP-II counterparts. This result offers an explanation for the selectivity of fumagillin for the eukaryotic MetAP-II enzyme.

Key words: Methionine aminopeptidase; Angiogenesis inhibition; Irreversible inhibitors; Molecular dynamics simulation

Address correspondence to Christian D. P. Klein, Pharmaceutical and Medicinal Chemistry, University of the Saarland FR 8.5, P.O. Box 151150, D-66111 Saarbruecken, Germany. Tel: +49-681-302-2924; Fax: +49-681-302-4386; E-mail: cdpk@mx.uni-sb.de

Oncology Research, Volume 13, pp. 521-528
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Copyright © 2003 Cognizant Comm. Corp.
Printed in the USA. All rights reserved.

In Vitro Antitumor SAR of threo/cis/threo/cis/erythro bis-THF Acetogenins: Correlations With Their Inhibition of Mitochondrial Complex I

Inmaculada Royo,1 Nuria DePedro,1 Ernesto Estornell,2 Diego Cortes,3 Fernando Peláez,1 and José R. Tormo1

1CIBE-Merck Research Laboratories, MERCK, SHARP & DOHME de ESPAÑA S.A., C/ Josefa Valcárcel, 38, Madrid 28027, Spain
2Departament de Bioquímica i Biologia Molecular and 3Departament de Farmacologia Facultat de Farmàcia, Universitat de València, Avgd. Vicent Andrés Estellés s/n, Burjassot 46100, València, Spain

Annonaceous acetogenins (ACG) are a large family of natural products that have been described as the most potent in vitro inhibitors of the mitochondrial respiratory chain Complex I. During the last two decades a large number of related structures have been discovered, increasing the number of members of this family. The large diversity of structural moieties and the general trends observed for inhibiting both growth of tumor cell lines and mitochondrial respiratory chain activity have resulted in the classification of these compounds into several structural groups according to their potency. Among them, the adjacent bis-tetrahydrofuranic acetogenins (bis-THF ACG) with a threo/cis/threo/cis/erythro relative configuration, have been described as the most potent subgroup, the prototypical member of which, rolliniastatin-1, was originally isolated from Rollinia membranacea seeds. In this report we describe the different structure-activity relationships (SAR) observed for some natural ACG and semisynthetic derivatives as growth inhibitors of human tumor breast, lung, liver, and colon cell lines. All the compounds assayed showed potencies in the micromolar range. Trends observed in the cytotoxicity assay have been compared with previous data reported for these compounds as inhibitors of mitochondrial respiratory chain.

Key words: Cancer; Cytotoxicity; Acetogenins; Tumor cell line growth inhibitors; Mitochondrial respiratory chain inhibitors

Address correspondence to Inmaculada Royo, CIBE-Merck Research Laboratories, MERCK, SHARP & DOHME de ESPAÑA S.A., C/ Josefa Valcárcel, 38, Madrid 28027, Spain. Tel: +34 91 321 0600; Fax: +34 91 321 1700; E-mail: inmaculada_royo@merck.com

Oncology Research, Volume 13, pp. 529-535
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Copyright © 2003 Cognizant Comm. Corp.
Printed in the USA. All rights reserved.
SAR: Flavonoids and COX-2 Inhibition

Herbert S. Rosenkranz1,2 and Bhavani P. Thampatty2

1Department of Biomedical Sciences, Florida Atlantic University, Boca Raton, FL 33431-0991
2Department of Environmental and Occupational Health, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, PA 15261

An analysis based upon structure-activity relationships (SAR) of the COX-2-inhibiting properties of flavonoids, a group of potential cancer chemopreventative agents, reveals that there is a dual structural basis for these activities. Each of these structural determinants (pharmacophores) alone is sufficient for activity. One of the pharmacophores is a 2D 6.9 Å distance descriptor that spans the A and C rings and includes the 4-OXO and 7-hydroxyl moieties. The potency associated with that pharmacophore is determined by a series of structural modulators that can increase, decrease, or even abolish the COX-2-inhibiting potential associated with that pharmacophore. The second pharmacophore describes a para-substituted phenolic B ring that requires unsubstituted meta and ortho positions. Based upon this, it indicates that hydroxylation at the 4´-position and a free 5´-position are sufficient for COX-2-inhibiting activity. The potency associated with this pharmacophore is modulated by log P2 and by the molecular weight.

Key words: Flavonoids; COX-2 inhibition; Structure-activity relationship; Pharmacophores

Address correspondence to H. S. Rosenkranz, Department of Biomedical Sciences, Florida Atlantic University, 777 Glades Road, P.O. Box 3091, Boca Raton, FL 33431. Tel: (561) 297-1188; Fax: (561) 297-2221; E-mail: rosenkra@fau.edu

Oncology Research, Volume 13, pp. 537-549
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Copyright © 2003 Cognizant Comm. Corp.
Printed in the USA. All rights reserved.
Synthesis and Antiproliferative Activity of Basic Ethers of 1,2-Dihydropyrrolo[1,2-a]indole, 6H-Isoindolo[2,1-a]indole, and 6H-Benz[5,6]isoindolo[2,1-a]indole

Jean Guillaumel,1 Stéphane Léonce,2 Alain Pierré,2 Pierre Renard,3 Bruno Pfeiffer,3 Laure Peruchon,4 Paola B. Arimondo,4 and Claude Monneret1

1Service de Chimie de l'Institut Curie, UMR 176 CNRS, 26 rue d'Ulm, F-75248 Paris Cedex 05, France
2Institut de Recherches Servier 11 rue des Moulineaux, 92450 Suresnes, France
3Laboratoire Servier, 1 rue Carl Hébert, 92415 Courbevoie cedex, France
4Laboratoire de Biophysique, CNRS UMR8646-MNHN USM0503, INSERM UR565, 43 rue Cuvier, 75231 Paris cedex 05, France

Monobasic ethers of 1,2-dihydropyrrolo[1,2-a]indole, 6H-isoindolo[2,1-a]indole, and 6H-benz[5,6]isoindolo[2,1-a]indole and bis-basic ethers of 6H-isoindolo[2,1-a]indole were prepared using an intramolecular Wittig cyclization as a key step. All these compounds were firstly evaluated for their cytotoxicity effects against L1210 cell line. Only the tetracyclic bis-basic ether 14d displayed submicromolar cytotoxic effect. Moreover, despite the fact that the presence of these two amino side chains in 14c, 14d, and 14f led to strong DNA binding effect, they are not topoisomerase II inhibitors. Among the monobasic ethers 14a, 14b, 22, and 29, which do not bind to DNA, the pentacyclic analog 29 exhibited micromolar cytotoxic activity against L1210 and HT-29 cell lines and induced a weak topoisomerase II inhibition.

Key words: Pyrrolo[1,2-a]indole; Isoindolo[2,1-a]indole; Benz[5,6]isoindolo[2,1-a]indole; Wittig reaction; Cancer; Basic ether; Intercalating agent

Address correspondence to Claude Monneret, Service de Chimie de l'Institut Curie, UMR 176 CNRS, 26 rue d'Ulm, F-75248 Paris Cedex 05, France. Tel: +33 142346655; Fax: +33 142346631; E-mail: claude.monneret@curie.fr

Oncology Research, Volume 13, pp. 551-559
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Copyright © 2003 Cognizant Comm. Corp.
Printed in the USA. All rights reserved.
Molecular and Functional Characterization of the Extracellular Calcium-Sensing Receptor in Human Colon Cancer Cells

Enikö Kállay,1 Elisabeth Bonner,3 Friedrich Wrba,2 Rajesh V. Thakker,4 Meinrad Peterlik,1 and Heide S. Cross1

Departments of 1Pathophysiology, and 2Clinical Pathology, University of Vienna Medical School, Währinger Gürtel 18-20, A-1090 Vienna, Austria
3Department of Pathology, Krankenhaus Rudolfstiftung, Juchgasse 25, A-1030 Vienna, Austria
4Molecular Endocrinology Group, Nuffield Department of Clinical Medicine, Botnar Centre, Nuffield Orthopaedic Centre, Headington, Oxford, OX3 7LD, UK

Presence of a functional extracellular calcium-sensing receptor (CaR) is of particular relevance for the growth-inhibitory action of Ca2+ on human colon carcinoma cells. In order to detect CaR gene alterations that may have occurred during the tumorigenic process, we applied Southern blot, DNA sequence, and RT-PCR analysis to DNA from normal human colon mucosa and from cancerous lesions of different grading, as well as from primary cultured and established colonic carcinoma cell lines (e.g., Caco-2). No evidence was obtained for mutations or other sequence alterations in the CaR gene in any of the colon carcinoma cells analyzed. Only a differential expression of two splice variants of the CaR gene, which are generated by usage of different promoters in the 5´-untranslated region, was detected in colon carcinomas of different grade. From Western blot analysis a tendency towards lower CaR protein levels in carcinoma cells in parallel with tumor progression became apparent. Activation of the CaR by extracellular Ca2+ or by specific receptor agonists resulted in substantial growth inhibition in Caco-2 cells. Activation of the CaR was transduced into inhibition of phospholipase A2-mediated arachidonic acid formation, but also into increased production of cAMP and IP3. This provides evidence for a cell type-specific function of the CaR in human colonocytes. We conclude that neoplastic colon epithelial cells can respond to antimitogenic signals generated by activation of the CaR as long as they express sufficient amounts of the CaR protein. This provides a rationale for the use of calcium in chemoprevention of colon tumor development.

Key words: Colon carcinoma progression; CaR gene expression; Caco-2 cells; Signal transduction; Proliferation

Address correspondence to Dr. Enikö Kállay, Department of Pathophysiology, Währinger Gürtel 18-20, A-1090 Vienna, Austria. Tel: +43-1-40400-5133; Fax: +43-1-40400-5130; E-mail: kallay.enikoe@akh-wien.ac.at

Oncology Research, Volume 13, pp. 561-566
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Copyright © 2003 Cognizant Comm. Corp.
Printed in the USA. All rights reserved.
Synergistic Interaction Between Cyclophosphamide or Paclitaxel and the Bioreductive Compound NLCPQ-1, In Vivo

M. V. Papadopoulou, M. Ji, and W. D. Bloomer

The Department of Radiation Medicine at Evanston Northwestern Healthcare, 2650 Ridge Avenue, Evanston, IL 60201

The antitumor effect of cyclophosphamide (CPM) and paclitaxel was investigated in BALB/c mice bearing EMT6 tumors, in combination with the bioreductive compound NLCPQ-1 by using the in vivo/in vitro assay as the endpoint. An optimum administration schedule for a synergistic interaction between NLCPQ-1 and CPM/paclitaxel was determined and dose modification factors (DMF) were calculated for antitumor effect and bone marrow toxicity. All drugs were given by IP injection; NLCPQ-1 at 15 mg/kg, which is much less than its maximally tolerated dose (MTD greater than 50 mg/kg), paclitaxel up to 25 mg/kg, and CPM up to 200 mg/kg. Bone marrow toxicity studies were performed in parallel by using a modified CFU-GM assay. A schedule-dependent synergistic interaction was observed for both chemotherapeutic agents combined with NLCPQ-1 but with entirely different patterns, as has been previously seen with the analog NLCQ-1. The optimal degree of potentiation, P (percentage of tumor cells that were killed due to clear potentiation), was 31 and 33 when NLCPQ-1 was administered 2 h before CPM and 3-3.5 h after paclitaxel, respectively. At the above time schedules, NLCPQ-1 modified the dose of CPM and paclitaxel, for 60% tumor cell killing, by a factor of 1.8 and 2.1, respectively. Bone marrow toxicity was not enhanced by combining either chemotherapeutic agent with NLCPQ-1. Comparison with results from previous similar studies with NLCQ-1 revealed that, on a molar basis, NLCPQ-1 was a less potent chemosensitizer than NLCQ-1. However, the results still suggest a potential clinical use of NLCPQ-1 as an adjuvant to CPM or paclitaxel therapy against solid tumors.

Key words: NLCPQ-1; Bioreductive drugs; Chemotherapeutic agents; Potentiation

Address correspondence to M. V. Papadopoulou, Evanston Northwestern Healthcare, The Department of Radiation Medicine, 2650 Ridge Avenue, Evanston, IL 60201. Tel: (847) 570-2262; Fax: (847) 570-1878; E-mail: m-papadopoulou@nwu.edu