title: Gimatecan and other camptothecin derivatives poison Leishmania DNA-topoisomerase IB leading to a strong leishmanicidal effect.
abstract: The aim of this work is the in vitro and ex vivo assessment of the leishmanicidal activity of camptothecin and three analogues used in cancer therapy: topotecan (Hycantim®), gimatecan (ST1481) and the pro-drug irinotecan (Camptosar®) as well as its active metabolite SN-38 against Leishmania infantum. The activity of camptothecin and its derivatives was studied on extracellular L. infantum infrared-emitting promastigotes and on an ex vivo murine model of infected splenocytes with L. infantum fluorescent amastigotes. In situ formation of SDS/KCl precipitable DNA-protein complexes in Leishmania promastigotes indicated that these drugs are DNA topoisomerase IB poisons. The inhibitory potency of camptothecin derivatives on recombinant L. infantum topoisomerase IB was assessed in vitro showing that gimatecan is the most active compound preventing the relaxation of supercoiled DNA at submicromolar concentrations. Cleavage equilibrium assays in Leishmania topoisomerase IB show that gimatecan changes the equilibrium towards cleavage at much lower concentrations than the other camptothecin derivatives and that this effect persists over time. Gimatecan and camptothecin were the most powerful compounds preventing cell growth of free-living L. infantum promastigotes within the same concentration range. All these compounds killed L. infantum splenocyte-infecting amastigotes within the nanomolar range. The amastigote form showed higher sensitivity to topoisomerase IB poisons (with high therapeutic selectivity indexes) than free-living promastigotes. All the compounds assayed poisoned L. infantum DNA topoisomerase IB leading to a strong leishmanicidal effect. Camptothecin derivatives are suitable for reducing the parasitic burden of ex vivo infected splenocytes. The selectivity index of gimatecan makes it a promising drug against this neglected disease.
authors: Departamento de Ciencias Biomédicas, Universidad de León, Campus de Vegazana s/n, 24071 León, Spain.
authors: Christopher F
authors: CF
authors: Prada
authors: Raquel
authors: R
authors: Alvarez-Velilla
authors: Rafael
authors: R
authors: Balaña-Fouce
authors: Carlos
authors: C
authors: Prieto
authors: Estefania
authors: E
authors: Calvo-Álvarez
authors: Jose Miguel
authors: JM
authors: Escudero-Martínez
authors: José María
authors: JM
authors: Requena
authors: César
authors: C
authors: Ordóñez
authors: Alessandro
authors: A
authors: Desideri
authors: Yolanda
authors: Y
authors: Pérez-Pertejo
authors: Rosa M
authors: RM
authors: Reguera
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology; D002166:Camptothecin / Q000031:analogs & derivatives* / Q000494:pharmacology*; D002478:Cells, Cultured; D004264:DNA Topoisomerases, Type I / Q000378:metabolism; D017930:Genes, Reporter; D020128:Inhibitory Concentration 50; D000077146:Irinotecan; D007700:Kinetics; D018314:Leishmania infantum / Q000187:drug effects* / Q000201:enzymology / Q000254:growth & development; D008018:Life Cycle Stages / Q000187:drug effects*; D008164:Luminescent Proteins; D051379:Mice; D011355:Prodrugs / Q000494:pharmacology*; D015800:Protozoan Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism; D013154:Spleen / Q000187:drug effects / Q000469:parasitology / Q000473:pathology; D059004:Topoisomerase I Inhibitors / Q000494:pharmacology*; D014344:Trypanocidal Agents / Q000494:pharmacology*; D000097573:Red Fluorescent Protein
chemical_list: D000970:Antineoplastic Agents; D002166:Camptothecin; D004264:DNA Topoisomerases, Type I; D000077146:Irinotecan; D008164:Luminescent Proteins; D011355:Prodrugs; D015800:Protozoan Proteins; D059004:Topoisomerase I Inhibitors; D014344:Trypanocidal Agents; D000097573:Red Fluorescent Protein; C433984:ST 1481