Dermacentor variabalis: Tick saliva inhibits osteosarcoma (Saos) cell migration and invasion

Abstract

Previous studies from our laboratory show that tick saliva inhibits fibroblast migration in both wound healing and chemotaxis assays. These results lead us to examine the effect of tick saliva on the invasiveness of Saos cells. Assessment of cell migration using a blind well assay showed that saliva decreased basal cell migration by 57.78+5.17% and inhibited stimulated migration by 67.41+8.87%. In addition[j1], saliva reduced SaOS invasiveness by 40% as measured by a matrigel invasion assay. Since extracellular signal‐regulated kinase (Erk) is involved in cellular movement and aberrant Akt activation contributes to increased cell invasiveness, we measured the effects of tick saliva on Akt and ERK activation by EGF. While EGF stimulation of ERK was not affected by tick saliva, Akt activation [j2]by 1 ng/ml EGF was inhibited ~55% (from 2.21+0.37 to 1.22+0.32). Our data indicate that a constituent(s) in tick saliva inhibits the invasiveness of an osteosarcoma cell and suggest that suppression of Akt signaling may be involved. Since metastasis of primary tumors often occurs in cancer, our data suggest the possibility of therapeutic agent(s) in tick saliva.