Dual Targeting of Insulin and Venus Kinase Receptors of Schistosoma mansoni for Novel Anti-schistosome Therapy

Abstract

BackgroundChemotherapy of schistosomiasis relies on a single drug, Praziquantel (PZQ) and mass-use of this compound has led to emergence of resistant strains of Schistosoma mansoni, therefore pointing out the necessity to find alternative drugs. Through their essential functions in development and metabolism, receptor tyrosine kinases (RTK) could represent valuable drug targets for novel anti-schistosome chemotherapies. Taking advantage of the similarity between the catalytic domains of S. mansoni insulin receptors (SmIR1 and SmIR2) and Venus Kinase Receptors (SmVKR1 and SmVKR2), we studied the possibility to fight schistosomes by targeting simultaneously the four receptors with a single drug.Methodology/Principal FindingsSeveral commercial RTK inhibitors were tested for their potential to inhibit the kinase activities of SmIR1, SmIR2, SmVKR1 and SmVKR2 intracellular domains (ICD) expressed in Xenopus oocytes. We measured the inhibitory effect of chemicals on meiosis resumption induced by the active ICD of the schistosome kinases in oocytes. The IR inhibitor, tyrphostin AG1024, was the most potent inhibitory compound towards SmIR and SmVKR kinases. In vitro studies then allowed us to show that AG1024 affected the viability of both schistosomula and adult worms of S. mansoni. At micromolar doses, AG1024 induced apoptosis and caused schistosomula death in a dose-dependent manner. In adult worms, AG1024 provoked alterations of reproductive organs, as observed by confocal laser scanner microscopy. With 5 µM AG1024, parasites were no more feeding and laying eggs, and they died within 48 h with 10 µM.Conclusion/SignificanceIRs and VKRs are essential in S. mansoni for key biological processes including glucose uptake, metabolism and reproduction. Our results demonstrate that inhibiting the kinase potential and function of these receptors by a single chemical compound AG1024 at low concentrations, leads to death of schistosomula and adult worms. Thus, AG1024 represents a valuable hit compound for further design of anti-kinase drugs applicable to anti-schistosome chemotherapy.

Compound library screening identified Akt/PKB kinase pathway inhibitors as potential key molecules for the development of new chemotherapeutics against schistosomiasis

“…Most of them are ATP-competitive. S. mansoni adult worm couples, freshly recovered from infected hamsters, were maintained in the culture conditions previously defined ( Vanderstraete et al, 2013b ), and we analyzed the level of male-female pairing and egg laying following 24, 48 or 72 h of exposure to each inhibitor added at a 10 μM final concentration. Results ( Table S1 ) indicated a highly variable effect of each inhibitor on worms, ranging from a complete (100%) inhibition of pairing and/or egg laying at 24 h to a totally unaffected, as compared to untreated parasites, worm behaviour following 72 h of culture.…”

Effect of clinically approved HDAC inhibitors on Plasmodium, Leishmania and Schistosoma parasite growth

“…Negative and positive controls, including untreated schistosomula, killed larvae (70% ethanol) and schistosomula exposed to praziquantel (PZQ) were included in each assay. The stability of adult worm pairs and egg laying in culture were measured as previously described (Vanderstraete et al., 2013). All assays were performed in triplicate on two separate occasions.…”

Schistosoma mansoni Sirtuins: Characterization and Potential as Chemotherapeutic Targets

“…To measure the effect of sirtuin inhibitors on adult worm pairing in culture [45] S. mansoni adult worms obtained from hamsters were washed in M199 medium and ten pairs of adult worms were transferred to each well of a 6-well culture plate containing 2 mL of M199 completed medium. The worms were cultured during 6 days at 37°C in a humid atmosphere containing 5% CO 2 , and then two different concentrations of sirtuin inhibitors (10 and 20 µM) were tested.…”