title: Topoisomerase I-mediated DNA cleavage as a guide to the development of antitumor agents derived from the marine alkaloid lamellarin D: triester derivatives incorporating amino acid residues.
abstract: The marine alkaloid lamellarin D (LAM-D) has been recently characterized as a potent poison of human topoisomerase I endowed with remarkable cytotoxic activities against tumor cells. We report here the first structure-activity relationship study in the LAM-D series. Two groups of triester compounds incorporating various substituents on the three phenolic OH at positions 8, 14 and 20 of 6H-[1]benzopyrano[4',3':4,5]pyrrolo[2,1-a]isoquinolin-6-one pentacyclic planar chromophore typical of the parent alkaloid were tested as topoisomerase I inhibitors. The non-amino compounds in group A showed no activity against topoisomerase I and were essentially non cytotoxic. In sharp contrast, compounds in group B incorporating amino acid residues strongly promoted DNA cleavage by human topoisomerase I. LAM-D derivatives tri-substituted with leucine, valine, proline, phenylalanine or alanine residues, or a related amino side chain, stabilize topoisomerase I-DNA complexes. The DNA cleavage sites detected at T downward arrow G or C downward arrow G dinucleotides with these molecules were identical to that of LAM-D but slightly different from those seen with camptothecin which stimulates topoisomerase I-mediated cleavage at T downward arrow G only. In the DNA relaxation and cleavage assays, the corresponding Boc-protected compounds and the analogues of the non-planar LAM-501 derivative lacking the 5-6 double bond in the quinoline B-ring showed no effect on topoisomerase I and were considerably less cytotoxic than the corresponding cationic compounds in the LAM-D series. The presence of positive charges on the molecules enhances DNA interaction but melting temperature studies indicate that DNA binding is not correlated with topoisomerase I inhibition or cytotoxicity. Cell growth inhibition by the 41 lamellarin derivatives was evaluated with a panel of tumor cells lines. With prostate (DU-145 and LN-CaP), ovarian (IGROV and IGROV-ET resistant to ecteinascidin-743) and colon (LoVo and LoVo-Dox cells resistant to doxorubicin) cancer cells (but not with HT29 colon carcinoma cells), the most cytotoxic compounds correspond to the most potent topoisomerase I poisons. The observed correlation between cytotoxicity and topoisomerase I inhibition strongly suggests that topoisomerase I-mediated DNA cleavage assays can be used as a guide to the development of superior analogues in this series. LAM-D is the lead compound of a new promising family of antitumor agents targeting topoisomerase I and the amino acid derivatives appear to be excellent candidates for a preclinical development.
authors.affiliation: INSERM UR-524 and Laboratoire de Pharmacologie Antitumorale du Centre Oscar Lambret, IRCL, Place de Verdun, 59045 Lille, France.
authors.forename: Christelle
authors.initials: C
authors.lastname: Tardy
authors.forename: Michaël
authors.initials: M
authors.lastname: Facompré
authors.forename: William
authors.initials: W
authors.lastname: Laine
authors.forename: Brigitte
authors.initials: B
authors.lastname: Baldeyrou
authors.forename: Dolores
authors.initials: D
authors.lastname: García-Gravalos
authors.forename: Andrés
authors.initials: A
authors.lastname: Francesch
authors.forename: Cristina
authors.initials: C
authors.lastname: Mateo
authors.forename: Alfredo
authors.initials: A
authors.lastname: Pastor
authors.forename: José A
authors.initials: JA
authors.lastname: Jiménez
authors.forename: Ignacio
authors.initials: I
authors.lastname: Manzanares
authors.forename: Carmen
authors.initials: C
authors.lastname: Cuevas
authors.forename: Christian
authors.initials: C
authors.lastname: Bailly
mesh_terms: D000470:Alkaloids / Q000138:chemical synthesis / Q000737:chemistry* / Q000494:pharmacology; D000596:Amino Acids / Q000737:chemistry*; D000818:Animals; D000970:Antineoplastic Agents / Q000138:chemical synthesis / Q000737:chemistry* / Q000494:pharmacology; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D003374:Coumarins / Q000138:chemical synthesis / Q000737:chemistry* / Q000494:pharmacology; D004247:DNA / Q000737:chemistry* / Q000378:metabolism; D004264:DNA Topoisomerases, Type I / Q000737:chemistry* / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D015195:Drug Design; D004354:Drug Screening Assays, Antitumor; D004952:Esters / Q000737:chemistry; D006576:Heterocyclic Compounds, 4 or More Rings / Q000138:chemical synthesis / Q000737:chemistry* / Q000494:pharmacology; D006801:Humans; D007546:Isoquinolines / Q000138:chemical synthesis / Q000737:chemistry* / Q000494:pharmacology; D015394:Molecular Structure; D013329:Structure-Activity Relationship; D059004:Topoisomerase I Inhibitors
chemical_list: D000470:Alkaloids; D000596:Amino Acids; D000970:Antineoplastic Agents; D003374:Coumarins; D004952:Esters; D006576:Heterocyclic Compounds, 4 or More Rings; D007546:Isoquinolines; D059004:Topoisomerase I Inhibitors; C455554:lamellarin D; D004247:DNA; D004264:DNA Topoisomerases, Type I