Targeting Echinococcus multilocularis PIM kinase for improving anti-parasitic chemotherapy

Background: The potentially lethal zoonosis alveolar echinococcosis (AE) is because the metacestode larval stage from the tapeworm Echinococcus multilocularis. Current AE treatments are restricted and depend on surgery and also on chemotherapy involving benzimidazoles (BZ). BZ treatment, however, is mainly parasitostatic only, should be given for prolonged periods of time, and it is connected with adverse negative effects. Novel treatments therefore are urgently needed.

Methodology/principal findings: By making use of an extensive selection of kinase inhibitors to E. multilocularis stem cell cultures we identified the proto-oncogene PIM kinase like a promising target for anti-AE chemotherapy. The gene encoding the particular E. multilocularis ortholog, EmPim, was characterised as well as in situ hybridization assays indicated its expression in parasite stem cells. By yeast two-hybrid assays we demonstrate interaction of EmPim with E. multilocularis CDC25, indicating an participation of EmPim in parasite cell cycle regulation. Small molecule compounds SGI-1776 and CX-6258, initially found to effectively hinder human PIM kinases, exhibited harmful effects on in vitro cultured parasite metacestode vesicles and avoided the development of mature vesicles from parasite stem cell cultures. To enhance compound specificity for EmPim, we applied a higher throughput in silico modelling approach, resulting in the identification of compound Z196138710. When put on in vitro cultured metacestode vesicles and parasite cell cultures, Z196138710 demonstrated equally harmful as SGI-1776 and CX-6258 but displayed considerably reduced toxicity towards human HEK293T and HepG2 cells.

Conclusions/significance: Repurposing of kinase inhibitors initially made to SGI-1776 affect mammalian kinases for helminth disease treatment methods are frequently hampered by adverse negative effects of particular compounds on human cells. Ideas demonstrate the utility of high throughput in silico methods to design small molecule compounds of greater specificity for parasite cells. We advise EmPim like a promising target for particular approaches towards AE treatment.