Effects of Pentamidine on Polyamine Level and Biosynthesis in Wild-Type, Pentamidine-Treated, and Pentamidine-ResistantLeishmania

Basselin, Mireille; Badet‐Denisot, Marie‐Ange; Lawrence, Françoise; Robert-Géro, Malka

doi:10.1006/expr.1996.4131

Cited by 46 publications

(31 citation statements)

References 29 publications

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“…For pentamidine, previously described mechanisms include DNA binding and consequent inhibition of DNA synthesis (41,42), modulation of polyamine levels (43), and calmodulin antagonism (44). Whereas pentamidine is known to possess DNA minor groove-binding activity (42,45), our studies indicate that it does not behave as a classical DNA-damaging agent in this A549 proliferation assay, nor simply as an inhibitor of DNA repair.…”

Section: Chtsmentioning

confidence: 99%

Systematic discovery of multicomponent therapeutics

Borisy

Elliott

Hurst

et al. 2003

Proc. Natl. Acad. Sci. U.S.A.

550

522

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Multicomponent therapies, originating through deliberate mixing of drugs in a clinical setting, through happenstance, and through rational design, have a successful history in a number of areas of medicine, including cancer, infectious diseases, and CNS disorders. We have developed a high-throughput screening method for identifying effective combinations of therapeutic compounds. We report here that systematic screening of combinations of small molecules reveals unexpected interactions between compounds, presumably due to interactions between the pathways on which they act. Through systematic screening of Ϸ120,000 different two-component combinations of reference-listed drugs, we identified potential multicomponent therapeutics, including (i) fungistatic and analgesic agents that together generate fungicidal activity in drug-resistant Candida albicans, yet do not significantly affect human cells, (ii) glucocorticoid and antiplatelet agents that together suppress the production of tumor necrosis factor-␣ in human primary peripheral blood mononuclear cells, and (iii) antipsychotic and antiprotozoal agents that do not exhibit significant antitumor activity alone, yet together prevent the growth of tumors in mice. Systematic combination screening may ultimately be useful for exploring the connectivity of biological pathways and, when performed with reference-listed drugs, may result in the discovery of new combination drug regimens.M odern biological research and much of drug discovery is often driven by the search for new molecularly targeted therapeutics (1-3). In this approach, a specific protein is studied in vitro, in cells and in whole organisms, and evaluated as a drug target for a specific therapeutic indication (3, 4). The refinement of this approach has resulted in the ability to discover compounds with great selectivity for a chosen protein target. The recent success of Gleevec (imatinib mesylate), an inhibitor of the breakpoint cluster regionabelson (BCR-ABL) kinase, and of selective cyclooxygenase-2 (COX-2) inhibitors Vioxx (rofecoxib) and Celebrex (celecoxib) are evidence that the target-based approach can be successful (5, 6).Systems biology, however, has revealed that human cells and tissues are composed of complex, networked systems with redundant, convergent and divergent signaling pathways (7-10). For example, the redundant function of proteins involved in cell-cycle regulation (11) has inspired efforts to intervene simultaneously at multiple points in these signaling pathways (12). A drug discovery approach consonant with this systems biology framework, and complementary to the target-based approach, entails identification of combinations of small molecules that perturb cellular signaling networks in a desired fashion.Recognition of the potential for multipoint intervention in biology and medicine has a long history. As early as 1928, Loewe (13) observed and quantified effects of combinations of compounds that were different from, and not predicted by, the activities of the constituents. The conc...

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Section: Chtsmentioning

confidence: 99%

Systematic discovery of multicomponent therapeutics

Borisy

Elliott

Hurst

et al. 2003

Proc. Natl. Acad. Sci. U.S.A.

550

522

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“…Pentavalent antimony undergoes an in vivo reduction into a trivalent form which is toxic to amastigotes and promastigotes. Pentamidine, which is able to substitute polyamines at their sites of binding to nucleic acids, might produce the inhibition of DNA replication and transcription (3), whereas amphotericin B is selectively toxic to parasites, probably due to its affinity to ergosterol, causing protozoan membrane damage (5).…”

mentioning

confidence: 99%

Differential Effects of Paromomycin on Ribosomes of Leishmania mexicana and Mammalian Cells

Fernández

Malchiodi

Algranati

2011

Antimicrob Agents Chemother

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Paromomycin, an aminoglycoside antibiotic having low mammalian cell toxicity, is one of the drugs currently used in the chemotherapy of cutaneous and visceral leishmaniasis. In order to understand the mode of action of this antibiotic at the molecular level, we have investigated the effects of paromomycin on protein synthesis in Leishmania and its mammalian hosts. We were able to demonstrate that in vivo protein synthesis in the promastigote stage of the parasite and its proliferation rate are markedly inhibited by paromomycin while being only slightly affected by other aminoglycoside antibiotics, such as streptomycin and neomycin B. Furthermore, both in vitro polypeptide synthesis induced by poly(U) as mRNA and accuracy of translation are significantly decreased by paromomycin in cell-free systems containing ribosomal particles of Leishmania promastigotes. Conversely, when ribosomes from mammalian cells are used instead of the protozoan particles, polyphenylalanine synthesis is only barely reduced by the antibiotic and the translation misreading remains almost unaltered. Surface plasmon resonance analysis of the interaction between paromomycin and protozoan or mammalian cell ribosomal RNAs shows a strong binding of antibiotic to the parasite ribosomal decoding site and practically no interaction with the mammalian cell counterpart. Our results indicating differential effects of paromomycin on the translation processes of the Leishmania parasite and its mammalian hosts can explain the therapeutic efficiency of this antibiotic as an antileishmaniasis agent.

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“…Our reverse genetic stratagem clearly indicates that the primary intracellular targets of DFMO and MDL73811 are ODC and ADOMETDC, respectively. Conversely, the cellular toxicities of pentamidine, berenil, and MGBG, all drugs postulated to inhibit polyamine metabolism (7,11,45), do not appear to be mediated through the targeting of the polyamine biosynthetic machinery in L. donovani promastigotes since the cytotoxicity profiles of the overproducer strains are virtually identical to those of wildtype parasites. These results reinforce previous observations that pentamidine, berenil, and MGBG have other cellular targets (8,9,41,62).…”

Section: Discussionmentioning

confidence: 99%

“…Effect of pentamidine, berenil, and MGBG on wild-type and polyamine biosynthetic enzyme overproducer strains. Pentamidine, berenil, and MGBG have previously been postulated to exert their toxicity by inhibiting the polyamine biosynthetic pathway (7,11,45). However, other cellular targets have also been proposed (8,9,41,43,62).…”

Section: Generationmentioning

confidence: 99%

Leishmania donovani Polyamine Biosynthetic Enzyme Overproducers as Tools To Investigate the Mode of Action of Cytotoxic Polyamine Analogs

Roberts

Jiang

Gasteier

et al. 2007

Antimicrob Agents Chemother

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A number of anticancer and antiparasitic drugs are postulated to target the polyamine biosynthetic pathway and polyamine function, but the exact mode of action of these compounds is still being elucidated. To establish whether polyamine analogs specifically target enzymes of the polyamine pathway, a model was developed using strains of the protozoan parasite Leishmania donovani that overproduce each of the polyamine biosynthetic enzymes. Promastigotes overexpressing episomal constructs encoding ornithine decarboxylase (ODC), Sadenosylmethionine decarboxylase (ADOMETDC), or spermidine synthase (SPDSYN) revealed robust overproduction of the corresponding polyamine biosynthetic enzyme. Polyamine pools, however, were either unchanged or only marginally affected, implying that regulatory mechanisms must exist. The ODC, ADOMETDC, and SPDSYN overproducer strains exhibited a high level of resistance to difluoromethylornithine, 5-{[(Z)-4-amino-2-butenyl]methylamino}-5-deoxyadenosine, and n-butylamine, respectively, confirming previous observations that these agents specifically target polyamine enzymes. Conversely, augmented levels of polyamine biosynthetic enzymes did not affect the sensitivity of L. donovani promastigotes to pentamidine, berenil, and mitoguazone, drugs that were postulated to target the polyamine pathway, implying alternative and/or additional targets for these agents. The sensitivities of wild-type and overproducing parasites to a variety of polyamine analogs were also tested. The polyamine enzyme-overproducing lines offer a rapid cell-based screen for assessing whether synthetic polyamine analogs exert their mechanism of action predominantly on the polyamine biosynthetic pathway in L. donovani. Furthermore, the drug resistance engendered by the amplification of target genes and the overproduction of the encoded protein offers a general strategy for evaluating and developing therapeutic agents that target specific proteins in Leishmania.Polyamines are ubiquitous organic cations that play critical but still not completely defined roles in key cellular processes such as cell proliferation, differentiation, and nucleic acid synthesis (6,17,19,34,35,59,65). Since polyamines are especially important to rapidly growing cells, the polyamine pathway has been targeted in a multiplicity of antineoplastic and antiparasitic drug regimens. Most notably, DL-␣-difluoromethylornithine (DFMO), an irreversible inhibitor of ornithine decarboxylase (ODC), the first enzyme in the polyamine biosynthesis pathway, is effectively curative against late-stage African sleeping sickness caused by the protozoan parasite Trypanosoma brucei gambiense (3,14,57). Interestingly, the selectivity of DFMO for the metabolic machinery of the parasite is not brought about by differential sensitivities of the parasite and human ODC enzymes to inactivation by DFMO but is rather due to a novel mechanism involving disparities in ODC turnover rates between T. brucei and the mammalian host (22,23). DFMO is also active against other trypanosome spe...

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Effects of Pentamidine on Polyamine Level and Biosynthesis in Wild-Type, Pentamidine-Treated, and Pentamidine-ResistantLeishmania

Cited by 46 publications

References 29 publications

Systematic discovery of multicomponent therapeutics

Systematic discovery of multicomponent therapeutics

Differential Effects of Paromomycin on Ribosomes of Leishmania mexicana and Mammalian Cells

Leishmania donovani Polyamine Biosynthetic Enzyme Overproducers as Tools To Investigate the Mode of Action of Cytotoxic Polyamine Analogs

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