Inhibition of melanoma cells tumorigenicity by the snake venom toxin jararhagin.

Skmel-28 human melanoma cells were treated with jararhagin (Jara), a metalloproteinase disintegrin isolated from Bothrops jararaca snake venom, and Jari (Jara with the catalytic domain inactivated). Following treatments, monolayer cells lost cytoplasmic expansions acquiring round shapes, detached and formed cell clusters in suspension. Cytotoxicity effect of Jari was dramatically increased at concentrations higher than 0.4 microM, whereas cell adhesion responses did not differ significantly between similar concentrations of Jara and Jari. Treated cells were significantly inhibited to adhere to non-coated wells, as to ECM proteins-coated plates. Migration and invasion were also significantly inhibited in vitro. A decreased proliferation rate was observed in toxin-treated cells. Immunofluorescence staining showed a wide distribution of Jari across the cells. Jara treated cells (67.5%) steady bound anti-jara antibodies after 90 min, while Jari treated cells steady bound only after 6h (57.3%), as determined by FACS. Skmel-28 melanoma cells tumorigenicity was evaluated 180 days after s.c. injections in AIRmin mice. A statistically significant decrease in the ability of Jara and Jari treated cells to promote lung metastasis was observed. These results point to the potential use of this toxin as a tool for applied researches in the clinical field.