Assessment of anti-cancer potential of Hyalomma dromedarii salivary glands extract: in vitro study

Cancer is still one of the deadly diseases worldwide and the need for naturally-derived effectors is a pursued aim in health research. With the outstanding ability to bypass the host's various defense mechanisms, tick saliva constitutes an interesting rich source for the discovery of therapeutically-valuable molecules. Therefore, the present work aimed to evaluate the anti-tumor potential of Hyalomma dromedarii salivary glands extract (SGE). Three cell lines were used in this study, namely HCT116 (colorectal cancer), A549 (lung cancer) and HFB4 (normal skin) cells. MTT assay and light microscopy revealed significant dose-dependent inhibition of proliferation with obvious morphological changes in tested cell lines. Colon cells exhibited more sensitivity than lung ones, therefore they were selected for further investigations. Although cytotoxic effects were observed in treated-HFB4 cells, its IC50 value was much higher than that of HCT116 cells. Flow cytometry analysis of treated HCT116 cells showed accumulation of cellular DNA at the G2/M phase and induction of apoptosis. In addition, RT-qPCR indicated down-regulation in the expression of vascular endothelial growth factor (VEGF), fibroblast growth factor-2 (FGF-2), transforming growth factor-beta (TGF-beta) and interleukin-4 (IL-4) genes. These results demonstrated that H. dromedarii SGE has anti-proliferative, apoptotic and anti-angiogenic potential. Also, they open perspectives for characterization of effective molecules that could be used in developing treatments for colorectal cancer. Further investigations are required to identify the mechanisms, molecules and signaling pathways involved in the inhibitory effect of the SGE.