Mutual action of anticancer and antiparasitic drugs: are there any shared targets?

Giardia telomeres and telomerase

Giardia duodenalis, the protozoan responsible for giardiasis, is a significant contributor to millions of diarrheal diseases worldwide. Despite the availability of treatments for this parasitic infection, therapeutic failures are alarmingly frequent. Thus, there is a clear need to identify new therapeutic targets. Giardia telomeres were previously identified, but our understanding of these structures and the critical role played by Giardia telomerase in maintaining genomic stability and its influence on cellular processes remains limited. In this regard, it is known that all Giardia chromosomes are capped by small telomeres, organized and protected by specific proteins that regulate their functions. To counteract natural telomere shortening and maintain high proliferation, Giardia exhibits constant telomerase activity and employs additional mechanisms, such as the formation of G-quadruplex structures and the involvement of transposable elements linked to telomeric repeats. Thus, this study aims to address the existing knowledge gap by compiling the available information (until 2023) about Giardia telomeres and telomerase, focusing on highlighting the distinctive features within this parasite. Furthermore, the potential feasibility of targeting Giardia telomeres and/or telomerase as an innovative therapeutic strategy is discussed.

A novel palladium complex with a coumarin-thiosemicarbazone hybrid ligand inhibits Trypanosoma cruzi release from host cells and lowers the parasitemia in vivo

In this work, two analogous coumarin-thio and semicarbazone hybrid compounds were prepared and evaluated as a potential antichagasic agents. Furthermore, palladium and platinum complexes with the thiosemicarbazone derivative as ligand (L1) were obtained in order to establish the effect of metal complexation on the antiparasitic activity. All compounds were fully characterized both in solution and in solid state including the resolution of the crystal structure of the palladium complex by X-ray diffraction methods. Unexpectedly, all experimental and theoretical characterizations in the solid state, demonstrated that the obtained palladium and platinum complexes are structurally different: [PdCl(L1)] and [PtCl2(HL1)]. All the studied compounds lower the proliferation of the amastigote form of Trypanosoma cruzi while some of them also have an effect on the trypomastigote stage. Additionally, the compounds inhibit T. cruzi release from host cells in variable extents. The Pd compound presented a remarkable profile in all the in vitro experiments, and it showed no toxicity for mammalian cells in the assayed concentrations. In this sense, in vivo experiments were performed for this compound using an acute model of Chagas disease. Results showed that the complex significantly lowered the parasite count in the mice blood with no significant toxicity.

Polyaromatic Bis(indolyl)methane Derivatives with Antiproliferative and Antiparasitic Activity

Bis(indolyl)methanes (BIMs) are a class of compounds that have been recognized as an important core in the design of drugs with important pharmacological properties, such as promising anticancer and antiparasitic activities. Here, we explored the biological activity of the BIM core functionalized with different (hetero)aromatic moieties. We synthesized substituted BIM derivatives with triphenylamine, N,N-dimethyl-1-naphthylamine and 8-hydroxylquinolyl groups, studied their photophysical properties and evaluated their in vitro antiproliferative and antiparasitic activities. The triphenylamine BIM derivative 2a displayed an IC50 of 3.21, 3.30 and 3.93 μM against Trypanosoma brucei, Leishmania major and HT-29 cancer cell line, respectively. The selectivity index demonstrated that compound 2a was up to eight-fold more active against the parasites and HT-29 than against the healthy cell line MRC-5. Fluorescence microscopy studies with MRC-5 cells and T. brucei parasites incubated with derivative 2a indicate that the compound seems to accumulate in the cell's mitochondria and in the parasite's nucleus. In conclusion, the BIM scaffold functionalized with the triphenylamine moiety proved to be the most promising antiparasitic and anticancer agent of this series.

The nucleolus of Giardia and its ribosomal biogenesis

Giardia duodenalis is a protozoan intestinal parasite that causes a significant number of infections worldwide each year, particularly in low-income and developing countries. Despite the availability of treatments for this parasitic infection, treatment failures are alarmingly common. As a result, new therapeutic strategies are urgently needed to effectively combat this disease. On the other hand, within the eukaryotic nucleus, the nucleolus stands out as the most prominent structure. It plays a crucial role in coordinating ribosome biogenesis and is involved in vital processes such as maintaining genome stability, regulating cell cycle progression, controlling cell senescence, and responding to stress. Given its significance, the nucleolus presents itself as a valuable target for selectively inducing cell death in undesirable cells, making it a potential avenue for anti-Giardia treatments. Despite its potential importance, the Giardia nucleolus remains poorly studied and often overlooked. In light of this, the objective of this study is to provide a detailed molecular description of the structure and function of the Giardia nucleolus, with a primary focus on its involvement in ribosomal biogenesis. Likewise, it discusses the targeting of the Giardia nucleolus as a therapeutic strategy, its feasibility, and the challenges involved.

Parasites as potential targets for cancer immunotherapy

Parasites and cancers have some common antigens. Much scientific evidence in the human population, animal models, and in vitro experiments exhibit that parasites have significant anti-cancer effects. The larval stage of the tapeworm Echinococcus granulosus, Toxoplasma gondii, Trypanosoma cruzy, Plasmodium's, and Trichinella spiralis are among the parasites that have been subjects of anti-cancer research in the last decades. Anti-tumor effects of parasites may be due to the direct impact of the parasites per se or indirectly due to the immune response raised against common antigens between malignant cells and parasites. This manuscript reviews the anti-cancer effects of parasites and possible mechanisms of these effects. Options for using parasites or their antigens for cancer treatment in the future have been discussed.

Facing Diseases Caused by Trypanosomatid Parasites: Rational Design of Pd and Pt Complexes With Bioactive Ligands

Human African Trypanosomiasis (HAT), Chagas disease or American Trypanosomiasis (CD), and leishmaniases are protozoan infections produced by trypanosomatid parasites belonging to the kinetoplastid order and they constitute an urgent global health problem. In fact, there is an urgent need of more efficient and less toxic chemotherapy for these diseases. Medicinal inorganic chemistry currently offers an attractive option for the rational design of new drugs and, in particular, antiparasitic ones. In this sense, one of the main strategies for the design of metal-based antiparasitic compounds has been the coordination of an organic ligand with known or potential biological activity, to a metal centre or an organometallic core. Classical metal coordination complexes or organometallic compounds could be designed as multifunctional agents joining, in a single molecule, different chemical species that could affect different parasitic targets. This review is focused on the rational design of palladium(II) and platinum(II) compounds with bioactive ligands as prospective drugs against trypanosomatid parasites that has been conducted by our group during the last 20 years.

Encapsulating Anti-Parasite Benzimidazole Drugs into Lipid-Coated Calcium Phosphate Nanoparticles to Efficiently Induce Skin Cancer Cell Apoptosis

Benzimidazole (BMZ) family of anti-worm drugs has been now repurposed as anti-cancer drugs. However, offering a general reformulation method for these drugs is essential due to their hydrophobicity and low aqueous solubility. In this work, we developed a general approach to load typical BMZ drugs as tiny nanocrystals within lipid-coated calcium phosphate (LCP) nanoparticles. BMZ drug-loaded LCP nanoparticles increased their solubility in PBS by 100–200% and significantly enhanced the anti-cancer efficacy in the treatment of B16F0 melanoma cells. These drug-LCP nanoparticles induced much more cancer cell apoptosis, generated much more reactive oxygen species (ROS) and inhibited Bcl-2 expression of cancer cells. Moreover, BMZ drug-loaded LCP nanoparticles caused morphological change and extension disruption of cancer cells, and significantly reduced migration activity, representing high possibility for inhibition of tumor dissemination and metastasis. Very advantageously, BMZ drug-loaded LCP nanoparticles did not show any obvious toxicity, Bcl-2 inhibition and morphological changes in HEK293T healthy cells. In conclusion, BMZ drug-incorporated LCP nanoformulations may be a valuable nanomedicine that is able to inhibit primary tumors and prevent tumor dissemination with minimum side effects on healthy cells and tissues.

Repositioning of Antiparasitic Drugs for Tumor Treatment

Drug repositioning is a strategy for identifying new antitumor drugs; this strategy allows existing and approved clinical drugs to be innovatively repurposed to treat tumors. Based on the similarities between parasitic diseases and cancer, recent studies aimed to investigate the efficacy of existing antiparasitic drugs in cancer. In this review, we selected two antihelminthic drugs (macrolides and benzimidazoles) and two antiprotozoal drugs (artemisinin and its derivatives, and quinolines) and summarized the research progresses made to date on the role of these drugs in cancer. Overall, these drugs regulate tumor growth via multiple targets, pathways, and modes of action. These antiparasitic drugs are good candidates for comprehensive, in-depth analyses of tumor occurrence and development. In-depth studies may improve the current tumor diagnoses and treatment regimens. However, for clinical application, current investigations are still insufficient, warranting more comprehensive analyses.

Gold(III) complexes with thiosemicarbazonate ligands as potential anticancer agents: Cytotoxicity and interactions with biomolecular targets

Gold(III) complexes have been studied for the past years due to their anticancer properties and great affinity to biotargets, such as enzymes and proteins, which support their pharmacological applications. Within this scope, in this work the antiproliferative activities of two Au(III)-thiosemicarbazonate complexes, [AuClL₁] (1, L₁: (E,Z)-N-ethyl-N'-(3-nitroso-kN)butan-2-ylidene)carbamohydrazonothioato-k²N²,S) and [Au(Hdamp)L₂]Cl (2, L₂: N-(N'',N''-diethylaminothiocarbonyl)-N'(N''', N'''-dimethylcarbothioamide)benzamidineto-kN,k²S and Hdamp: 2-(N,N-dimethylaminomethyl)-phenyl-C¹), and their affinities to possible biological targets were investigated. Three different tumor cell lines were used to perform the cytotoxicity assays, including one cisplatin-resistant model, and the results showed lower EC₅₀ for 1 over 2 in every case: B16F10 (4.1 μM and 15.6 μM), A431 (4.0 μM and >50 μM) and OVCAR3 (4.2 μM and 24.5 μM). However, a lower toxicity to fibroblast 3T3 cell line was observed for 2 (30.58 μM) when compared to 1 (7.17 μM), resulting in comparable therapeutic indexes. Both complexes presented strong affinity to HSA: they distorted the secondary structure of the protein, as verified by circular dichroism, but 1 additionally presented the apparent fluorescence quenching constant (K_app) ten times greater than 2, which was probably due to the fact of 1 being able to denature HSA. The ethidium bromide displacement assay showed that neither 1 nor 2 are strong DNA intercalators, which is in agreement with what was observed through the UV-vis titration. In both cases, the 260 nm band presented hyperchromism, which can indicate ionic interactions or DNA damage. In fact, 1 was able to damage the pGEM plasmid, similarly to cisplatin, as verified by agarose gel electrophoresis and Atomic Force Microscopy. Biophysical studies in cancer cells model membranes were also performed in order to investigate the interaction of the gold complexes to lipid bilayers and revealed that the compounds interact with the membranes by exhibiting partition coefficients of 10³ order of magnitude. Overall, both complexes were found to be promising candidates for the development of a future anticancer drug against low sensitive or cisplatin resistant tumors.

Marine-Derived Macrocyclic Alkaloids (MDMAs): Chemical and Biological Diversity

The curiosity and attention that researchers have devoted to alkaloids are due to their bioactivities, structural diversity, and intriguing chemistry. Marine-derived macrocyclic alkaloids (MDMAs) are considered to be a potential source of drugs. Trabectedin, a tetrahydroisoquinoline derivative, has been approved for the treatment of metastatic soft tissue sarcoma and ovarian cancers. MDMAs displayed potent activities that enabled them to be used as anticancer, anti-invasion, antimalarial, antiplasmodial, and antimicrobial. This review presents the reported chemical structures, biological activities, and structure-activity relationships of macrocyclic alkaloids from marine organisms that have been published since their discovery until May 2020. This includes 204 compounds that are categorized under eight subclasses: pyrroles, quinolines, bis-quinolizidines, bis-1-oxaquinolizidines, 3-alkylpiperidines, manzamines, 3-alkyl pyridinium salts, and motuporamines.

Multi-target heteroleptic palladium bisphosphonate complexes

Bisphosphonates are the most commonly prescribed drugs for the treatment of osteoporosis and other bone illnesses. Some of them have also shown antiparasitic activity. In search of improving the pharmacological profile of commercial bisphosphonates, our group had previously developed first row transition metal complexes with N-containing bisphosphonates (NBPs). In this work, we extended our studies to heteroleptic palladium-NBP complexes including DNA intercalating polypyridyl co-ligands (NN) with the aim of obtaining potential multi-target species. Complexes of the formula [Pd(NBP)₂(NN)]·2NaCl·xH₂O with NBP = alendronate (ale) or pamidronate (pam) and NN = 1,10 phenanthroline (phen) or 2,2'-bipyridine (bpy) were synthesized and fully characterized. All the obtained compounds were much more active in vitro against T. cruzi (amastigote form) than the corresponding NBP ligands. In addition, complexes were nontoxic to mammalian cells up to 50-100 µM. Compounds with phen as ligand were 15 times more active than their bpy analogous. Related to the potential mechanism of action, all complexes were potent inhibitors of two parasitic enzymes of the isoprenoid biosynthetic pathway. No correlation between the anti-T. cruzi activity and the enzymatic inhibition results was observed. On the contrary, the high antiparasitic activity of phen-containing complexes could be related to their ability to interact with DNA in an intercalative-like mode. These rationally designed compounds are good candidates for further studies and good leaders for future drug developments. Four new palladium heteroleptic complexes with N-containing commercial bisphosphonates and DNA intercalating polypyridyl co-ligands were synthesized and fully characterized. All complexes displayed high anti-T. cruzi activity which could be related to the inhibition of the parasitic farnesyl diphosphate synthase enzyme but mainly to their ability to interact DNA.

Antitumor and anti-nematode activities of α-mangostin

α-Mangostin, one of the major xanthones isolated from pericarp of mangosteen (Garcinia mangostana Linn), exhibits a wide range of pharmacological activities, including antioxidant, anti-inflammatory, antimicrobial as well as anticancer, both in in vitro and in vivo studies. In the present study, α-mangostin' anti-cancer and anti-parasitic properties were tested in vitro against three human cell lines, including squamous carcinoma (SCC-15) and glioblastoma multiforme (U-118 MG), compared to normal skin fibroblasts (BJ), and in vivo against Caenorhabditis elegans. The drug showed cytotoxic activity, manifested by decrease of cell viability, inhibition of proliferation, induction of apoptosis and reduction of adhesion at concentrations lower than 10 μM (the IC₅₀ values were 6.43, 9.59 and 8.97 μM for SCC-15, U-118 MG and BJ, respectively). The toxicity, causing cell membrane disruption and mitochondria impairment, was selective against squamous carcinoma with regard to normal cells. Moreover, for the first time anti-nematode activity of α-mangostin toward C. elegans was described (the LC₅₀ = 3.8 ± 0.5 μM), with similar effect exerted by mebendazole, a well-known anthelmintic drug.

Quantitative high-throughput phenotypic screening of pediatric cancer cell lines identifies multiple opportunities for drug repurposing

Drug repurposing approaches have the potential advantage of facilitating rapid and cost-effective development of new therapies. Particularly, the repurposing of drugs with known safety profiles in children could bypass or streamline toxicity studies. We employed a phenotypic screening paradigm on a panel of well-characterized cell lines derived from pediatric solid tumors against a collection of ∼3,800 compounds spanning approved drugs and investigational agents. Specifically, we employed titration-based screening where compounds were tested at multiple concentrations for their effect on cell viability. Molecular and cellular target enrichment analysis indicated that numerous agents across different therapeutic categories and modes of action had an antiproliferative effect, notably antiparasitic/protozoal drugs with non-classic antineoplastic activity. Focusing on active compounds with dosing and safety information in children according to the Children's Pharmacy Collaborative database, we identified compounds with therapeutic potential through further validation using 3D tumor spheroid models. Moreover, we show that antiparasitic agents induce cell death via apoptosis induction. This study demonstrates that our screening platform enables the identification of chemical agents with cytotoxic activity in pediatric cancer cell lines of which many have known safety/toxicity profiles in children. These agents constitute attractive candidates for efficacy studies in pre-clinical models of pediatric solid tumors.

Nanoformulations of albendazole as effective anticancer and antiparasite agents

Initially emerging as a widely used clinical antiparasitic drug, albendazole (ABZ) has been increasingly recognized as an effective anticancer agent due to its outstanding advantage, in other words, low toxicity to normal cells but high effectiveness against parasites and some tumors. The major challenge is its poor water solubility and subsequently low bioavailability. This article thus first reviews the brief achievements in using ABZ to treat parasites and cancers, and summarizes the basic mechanisms of action of ABZ. Then this article critically reviews recent nanotechnological strategies, in other words, formulating/conjugating it with carriers into nanoformulations, in practices of improving aqueous solubility and efficacy in treatment of tumors and parasites. Our expert opinions in this field are provided for more effective delivery of ABZ to treat tumors and parasites in vivo.

The Antileishmanial Potential of C-3 Functionalized Isobenzofuranones against Leishmania (Leishmania) Infantum Chagasi

Leishmaniases are diseases caused by protozoan parasites of the genus Leishmania. Clinically, leishmaniases range from cutaneous to visceral forms, with estimated global incidences of 1.2 and 0.4 million cases per year, respectively. The treatment of these diseases relies on multiple parenteral injections with pentavalent antimonials or amphotericin B. However, these pharmaceuticals are either too toxic or expensive for routine use in developing countries. These facts call for safer, cheaper, and more effective new antileishmanial drugs. In this investigation, we describe the results of the assessment of the activities of a series of isobenzofuran-1(3H)-ones (phtalides) against Leishmania (Leishmania) infantum chagasi, which is the main causative agent of visceral leishmaniasis in the New World. The compounds were tested at concentrations of 100, 75, 50, 25 and 6.25 µM over 24, 48, and 72 h. After 48 h of treatment at the 100 µM concentration, compounds 7 and 8 decreased parasite viability to 4% and 6%, respectively. The concentration that gives half-maximal responses (LC50) for the antileishmanial activities of compounds 7 and 8 against promastigotes after 24 h were 60.48 and 65.93 µM, respectively. Additionally, compounds 7 and 8 significantly reduced parasite infection in macrophages.