Effect of topoisomerase inhibitors and DNA-binding drugs on the cell proliferation and ultrastructure of Trypanosoma cruzi

Abstract

Trypanosomatids present unusual organelles, such as the kinetoplast that contains the mitochondrial DNA arranged in catenated circles. The nucleus of these protozoa presents distinct domains during interphase as well as a closed mitosis. DNA topoisomerases modulate the topological state of DNA by regulating supercoiling of the double-stranded DNA during replication, transcription, recombination and repair. Because topoisomerases play essential roles in cellular processes, they constitute a potential target for antitumour and antimicrobial drugs. In this study, the effects of various topoisomerase inhibitors and DNA-binding drugs were tested on the cellular proliferation and ultrastructure of the Trypanosoma cruzi epimastigote form Blastocrithidia culicis was used as a comparative model, which has a more relaxed kinetoplast DNA (kDNA) organization. The results showed that the eukaryotic topoisomerase I inhibitors camptothecin and rebeccamycin were the most effective compounds in the arrest of T. cruzi proliferation. Of the eukaryotic topoisomerase II inhibitors, mitoxantrone, but not merbarone, was effective against cell proliferation. The prokaryotic topoisomerase II inhibitors norfloxacin and enoxacin targeted the kinetoplast specifically, thus promoting ultrastructural kDNA rearrangement in B. culicis. Of the DNA-binding drugs, berenil caused remarkable kDNA disorganization. With the exception of camptothecin, there have been no previous evaluations of the compounds tested here on trypanosomatid ultrastructure. In conclusion, inhibitors of the same class may have different effects on trypanosomatid proliferation and ultrastructure. The results obtained in this work may help to reveal the mechanism of action of different topoisomerase inhibitors in trypanosomatids.

Unveiling the effects of berenil, a DNA-binding drug, on Trypanosoma cruzi: implications for kDNA ultrastructure and replication

“…1). Such an effect, as previously reported by Zuma et al (2011), may be related to the fact that this drug promotes remarkable modifications on kinetoplast DNA arrangement, but does not impair cell division. The control cells presented a typical organization, such as a nucleus containing condensed heterochromatin, one mitochondrion, a bar-shaped kinetoplast, a Golgi complex, and a flagellum (Fig.…”

“…The drug concentrations used in this work (2, 10, 20, and 50 μM) were determined according to data presented in previous reports (Portugal 1994;Witola et al 2005;Zuma et al 2011).…”

Indotecan (LMP400) and AM13-55: Two Novel Indenoisoquinolines Show Potential for Treating Visceral Leishmaniasis

“…The other subunit contains the catalytic amino acid (Tyr222), which acts by breaking one DNA strand by a specific nucleotide sequence (13). All of these features have also been found in the other protozoanborne NTDs pathogens: Trypanosoma brucei, the agent responsible for sleeping sickness in Africa (11), and T. cruzi, responsible for Chagas' disease in South America (36). However, despite the fact that these enzymes conserve their catalytic domains unchanged, they display two nonconserved regions, one at the C-terminal end of the large protomer and the other at the N-terminal end of the small protomer, which are extremely important in sensitivity to topoisomerase poisons (12).…”

New Treatments for Chagas Disease and the Relationship between Chagasic Patients and Cancers

“…The type I enzymes make a transient single stranded nick in absence of any high energy cofactor, whereas the type II enzymes make double-stranded breaks in the presence of ATP, which allows supercoils to be removed from the circular DNAs. Both types of enzymes have been characterized in kinetoplastid hemoflagellated protozoan parasites [123].…”