Anti-neoplastic activity of Amblyomma sculptum, Amblyomma parvum and Rhipicephalus sanguineus tick saliva on breast tumor cell lines

Abstract

Cancer is one of the most troubling diseases and is becoming increasingly common. Breast cancer has a high cure rate when diagnosed early, but when diagnosed late, treatment is frequently painful, devastating and unsuccessful. The search for new treatments that are more effective and less harmful has led to several substances and biomolecules from plants and animals with potential anti-tumor activity. Within this context, ticks have emerged as an excellent source of new molecules with a wide array of therapeutic properties. Various molecules in tick saliva have immunomodulatory, anticoagulant, anti-inflammatory and anti-tumor effects across different tumor cell lines. Our study evaluates the effect of saliva from three widespread and important tick species in Brazil (Amblyomma sculptum, Amblyomma parvum and Rhipicephalus sanguineus) on MCF-7, MDA-MB-231 breast cancer cell lines and on the non-neoplastic MCF-10A cell line. We found that tick saliva from all three tick species showed cytotoxicity to tumor cells (MCF-7, MDA-MB-231) but not to the non-tumor cells (MCF-10A). Morphological changes on the surface of MCF-7 and MDA-MB-231 tumor cells did not occur on the MCF-10A cells. We also demonstrated that tumor cells die by apoptosis induced by caspase-3 and caspase 7 activity, suggesting that intrinsic pathway apoptosis may be triggered by tick saliva. These changes were not observed in MCF10A cells, which remained broadly unchanged even after exposure to diverse types of saliva. These results suggest that tick saliva from these tick species is a source of molecules, or biomolecules, useful for the potential source for the development of new breast cancer drugs.