Publications > Casado et al

Mol Cancer Ther. 2008 May;7(5):1309-18. doi: 10.1158/1535-7163.MCT-07-2432. PubMed 18483318

Relevance of the Fanconi anemia pathway in the response of human cells to trabectedin.

Jose A Casado, Paula Rio, Esther Marco, Veronica Garcia-Hernandez, Alberto Domingo, Laura Perez, Juan Carlos Tercero, Juan Jose Vaquero, Beatriz Albella, Federico Gago, Juan A Bueren

Division of Hematopoiesis and Gene Therapy Program, Centro de Investigaciones Energeticas, Medioambientales y Tecnologicas, Avenida Complutense 22, 28040 Madrid, Spain.

Abstract

Trabectedin (Yondelis; ET-743) is a potent anticancer drug that binds to DNA by forming a covalent bond with a guanine in one strand and one or more hydrogen bonds with the opposite strand. Using a fluorescence-based melting assay, we show that one single trabectedin-DNA adduct increases the thermal stability of the double helix by >20 degrees C. As deduced from the analysis of phosphorylated H2AX and Rad51 foci, we observed that clinically relevant doses of trabectedin induce the formation of DNA double-strand breaks in human cells and activate homologous recombination repair in a manner similar to that evoked by the DNA interstrand cross-linking agent mitomycin C (MMC). Because one important characteristic of this drug is its marked cytotoxicity on cells lacking a functional Fanconi anemia (FA) pathway, we compared the response of different subtypes of FA cells to MMC and trabectedin. Our data clearly show that human cells with mutations in FANCA, FANCC, FANCF, FANCG, or FANCD1 genes are highly sensitive to both MMC and trabectedin. However, in marked contrast to MMC, trabectedin does not induce any significant accumulation of FA cells in G2-M. The critical relevance of FA proteins in the response of human cells to trabectedin reported herein, together with observations showing the role of the FA pathway in cancer suppression, strongly suggest that screening for mutations in FA genes may facilitate the identification of tumors displaying enhanced sensitivity to this novel anticancer drug.

Publications > Negri et al

J Med Chem. 2007 Jul 12;50(14):3322-33. doi: 10.1021/jm070381s. PubMed 17571868

Antitumor activity, X-ray crystal structure, and DNA binding properties of thiocoraline A, a natural bisintercalating thiodepsipeptide.

Ana Negri, Esther Marco, Veronica Garcia-Hernandez, Alberto Domingo, Antonio L Llamas-Saiz, Silvia Porto-Sanda, Ricardo Riguera, William Laine, Marie-Helene David-Cordonnier, Christian Bailly, Luis F Garcia-Fernandez, Juan Jose Vaquero, Federico Gago

Departamento de Farmacologia, Universidad de AlcalA, E-28871 Madrid, Spain.

Abstract

The marine natural product thiocoraline A displayed approximately equal cytotoxic activity at nanomolar concentrations in a panel of 12 human cancer cell lines. X-ray diffraction analyses of orthorhombic crystals of this DNA-binding drug revealed arrays of docked pairs of staple-shaped molecules in which one pendent hydroxyquinoline chromophore from each cysteine-rich molecule appears intercalated between the two chromophores of a facing molecule. This arrangement is in contrast to the proposed mode of binding to DNA that shows the two drug chromophores clamping two stacked base pairs, in agreement with the nearest-neighbor exclusion principle. Proof of DNA sequence recognition was obtained from both classical DNase I footprinting experiments and determination of the melting temperatures of several custom-designed fluorescently labeled oligonucleotides. A rationale for the DNA-binding behavior was gained when models of thiocoraline clamping a central step embedded in several octanucleotides were built and studied by means of unrestrained molecular dynamics simulations in aqueous solution.

Publications > Martinez et al

J Med Chem. 2004 Feb 26;47(5):1136-48. doi: 10.1021/jm0310434. PubMed 14971893

Benzo[f]azino[2,1-a]phthalazinium cations: novel DNA intercalating chromophores with antiproliferative activity.

Valentin Martinez, Carolina Burgos, Julio Alvarez-Builla, Geronimo Fernandez, Alberto Domingo, Raquel Garcia-Nieto, Federico Gago, Ignacio Manzanares, Carmen Cuevas, Juan J Vaquero

Departamento de Quimica Organica, Universidad de Alcala, 28871-Alcala de Henares, Madrid, Spain.

Abstract

New azaquinolizinium-type cations have been obtained from isochromane. The synthesis was completed over seven steps and included as the key feature an intramolecular Westphal condensation. This first example of the intramolecular process allowed the preparation of benzo[f]pyrido[2,1-a]phthalazinium and benzo[f]quino[2,1-a]phthalazinium salts, which were evaluated as DNA intercalators, DNA topoisomerase I inhibitors, and antiproliferative compounds. Both cationic systems behave as DNA intercalators and exhibit antiproliferative activity. The pentacyclic benzo[f]quino[2,1-a]phthalazinium cations also have an inhibitory effect on the catalytic activity of DNA topoisomerase I, without trapping of cleavage complexes. Structural characterization using density functional theory indicates that the fused ring systems are slightly nonplanar, and additional molecular modeling studies suggest a preferred orientation for the intercalating chromophores within a typical CpG or TpG intercalation site.

Publications > Cary et al

J Cell Sci. 1994 Jun;107 ( Pt 6):1609-22. PubMed 7962201

Vimentin's tail interacts with actin-containing structures in vivo.

R B Cary, M W Klymkowsky, R M Evans, A Domingo, J A Dent, L E Backhus

University of Colorado, Boulder 80309-0347.

Abstract

The tail domain of the intermediate filament (IF) protein vimentin is unnecessary for IF assembly in vitro. To study the role of vimentin's tail in vivo, we constructed a plasmid that directs the synthesis of a 'myc-tagged' version of the Xenopus vimentin-1 tail domain in bacteria. This polypeptide, mycVimTail, was purified to near homogeneity and injected into cultured Xenopus A6 cells. In these cells the tail polypeptide co-localized with actin even in the presence of cytochalasin. Two myc-tagged control polypeptides argue for the specificity of this interaction. First, a similarly myc-tagged lamin tail domain localizes to the nucleus, indicating that the presence of the myc tag did not itself confer the ability to co-localize with actin (Hennekes and Nigg (1994) J. Cell Sci. 107, 1019-1029). Second, a myc-tagged polypeptide with a molecular mass and net charge at physiological pH (i.e. -4) similar to that of the mycVimTail polypeptide, failed to show any tendency to associate with actin-containing structures, indicating that the interaction between mycVimTail and actin-containing structures was not due to a simple ionic association. Franke (1987; Cell Biol. Int. Rep. 11, 831) noted a similarity in the primary sequence between the tail of the type I keratin DG81A and vimentin. To test whether the DG81A tail interacted with actin-containing structures, we constructed and purified myc-tagged DG81A tail polypeptides. Unexpectedly, these keratin tail polypeptides were largely insoluble under physiological conditions and formed aggregates at the site of injection. While this insolubility made it difficult to determine if they associated with actin-containing structures, it does provide direct evidence that the tails of vimentin and DG81A differ dramatically in their physical properties. Our data suggest that vimentin's tail domain has a highly extended structure, binds to actin-containing structures and may mediate the interaction between vimentin filaments and microfilaments involved in the control of vimentin filament organization (Hollenbeck et al. (1989) J. Cell Sci. 92, 621; Tint et al. (1991) J. Cell Sci. 98, 375).

Publications > Dent et al

J Cell Biol. 1992 Nov;119(4):855-66. doi: 10.1083/jcb.119.4.855. PubMed 1429840

Host cell factors controlling vimentin organization in the Xenopus oocyte.

J A Dent, R B Cary, J B Bachant, A Domingo, M W Klymkowsky

Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder 80309-034.

Abstract

To study vimentin filament organization in vivo we injected Xenopus oocytes, which have no significant vimentin system of their own, with in vitro-synthesized RNAs encoding Xenopus vimentins. Exogenous vimentins were localized primarily to the cytoplasmic surface of the nucleus and to the subplasma membrane "cortex." In the cortex of the animal hemisphere, wild-type vimentin forms punctate structures and short filaments. In contrast, long anastomosing vimentin filaments are formed in the vegetal hemisphere cortex. This asymmetry in the organization of exogenous vimentin is similar to that of the endogenous keratin system (Klymkowsky, M. W., L. A. Maynell, and A. G. Polson. 1987. Development (Camb.). 100:543-557), which suggests that the same cellular factors are responsible for both. Before germinal vesicle breakdown, in the initial stage of oocyte maturation, large vimentin and keratin filament bundles appear in the animal hemisphere. As maturation proceeds, keratin filaments fragment into soluble oligomers (Klymkowsky, M. W., L. A. Maynell, and C. Nislow. 1991. J. Cell Biol. 114:787-797), while vimentin filaments remain intact and vimentin is hyperphosphorylated. To examine the role of MPF kinase in the M-phase reorganization of vimentin we deleted the conserved proline of vimentin's single MPF-kinase site; this mutation had no apparent effect on the prophase or M-phase behavior of vimentin. In contrast, deletion of amino acids 19-68 or 18-61 of the NH2-terminal "head" domain produced proteins that formed extended filaments in the animal hemisphere of the prophase oocyte. We suggest that the animal hemisphere cortex of the prophase oocyte contains a factor that actively suppresses the formation of extended vimentin filaments through a direct interaction with vimentin's head domain. During maturation this "suppressor of extended filaments" appears to be inactivated, leading to the formation of an extended vimentin filament system.

Publications > Klymkowsky et al

Cell Motil Cytoskeleton. 1989;14(3):309-31. doi: 10.1002/cm.970140302. PubMed 2684432

Functions of intermediate filaments.

M W Klymkowsky, J B Bachant, A Domingo

Department of Molecular, Cellular & Developmental Biology, University of Colorado, Boulder 80309-0347.

Abstract

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