Inhibition of mammary carcinoma cell proliferation in vitro by crotamin

P. Castanheira¹; L.M. Andrade¹; A.M. Góes¹; C. Chávez-Olórtegui¹

1 Departamento de Bioquímica-Imunologia, ICB, Universidade Federal de Minas Gerais, CEP: 31270901, Belo Horizonte-MG, Brasil

In this present work, we evaluated the effects of several venoms from poisonous animals on tumor growth, cytotoxicity to tumor cells and possible mechanism of antitumor activity. In vitro experiments were carried out using human cells in culture from mammary carcinoma (MDAMB-231 cells). To determine the cell viability and also cytotoxic effects of 4 different venoms in different concentrations, MTT (3-[4,5- Dimethylthiazol-2-yl]-2,5-diphenyl-tetrazolium bromide) assay was used. We observed that only the snake venom Crotalus durissus terrificus known as cascavel sul-americana has significant inhibitory effect upon cell viability. Fractions purified from C.durissusterrificus were than tested separately in the MTT assay and the inhibitory effect was addressed to crotamin, a 4.8 KDa basic protein. In order to verify if apoptosis is the mechanism by which crotamin inhibits cell growth and viability, propidium iodide (PI) assay was done. After incubation of the toxin with MDAMB-231 cells, 15 to 30% of them triggered apoptotic mechanism, against 5% in the control group (without toxin). The proliferation of MDAMB-231 cells and human peripheral blood mononuclear cells  were evaluated by H³-methyl thimidine (³H-TdR) incorporation after incubation with the toxin. We observed that  (³H-TdR) incorporation by both cells decreased severally when crotamin was present, indicating that crotamin may also inhibit cell proliferation. Our initial results suggests that  crotamin has an negative effect on tumor growth.

Support  by: CNPq, and FAPEMIG

Correspondence to: p_castanheira@yahoo.com.br