Morte de células de adenocarcinoma de mama humano por BnSP-6, uma fosfolipase A2 Lys-49 homóloga da peçonha de Bothrops pauloensis

Abstract

CHAPTER II: PLA2s from snake venom display various biological activities and currently, has been reported that have antitumor and antiangiogenic properties. This work shows the effects of phospholipase A2 (BnSP-6), a Lys 49 isolated from Bothrops pauloensis venom, on human breast cancer MDA-MB-231cell. PLA2 BnSP-6 caused a dose-dependent cytotoxicity at concentrations of 12.5 - 100 μg/mL and inhibited the cell adhesion. Interestingly the cytotoxic potential of BnSP-6 was significantly lower against MCF10A, a non-tumorigenic breast epithelial cell line, suggesting that the PLA2 presented a possible preference for targets in cancer cells. Analysis of cell death showed that BnSP-6 stimulated the autophagy process on MDA-MB-231 cell, as evidenced by labeling of autophagic vacuoles. Moreover, apoptosis/necrosis assays showed that MDA-MB-231 cell cultured in presence of BnSP-6 (10 and 50μg/mL) presented induction of both early and late apoptosis. Apoptosis of MDA-MB-231 cells was also confirmed by up regulation of different genes related to apoptosis pathway, such as TNF, TNFRSF10B, TNFRSF1A and CASP8 and decrease of anti-apoptotic genes expression (BCL2 and BCL2L). In addition, BnSP-6 caused remarkable gene expression increased of tumors suppressor BRCA2 and TP53. Finally, BnSP-6 induced down-regulation of Angiopoetin 1 gene (potent pro-angiogenic factor) and inhibited adhesion and migration of MDA-MB-231 cells suggesting pharmaceutical applications to this PLA2 as an antiangiogenic and anti-metastatic therapeutic agent. Taken together our results showed that PLA2 BnSP-6 presented antitumor potential that can be exploited as prototype for the design of new anticancer therapies.