The aim of this study was to evaluate the anti-tumor activity of Amblyomin-X, a serine protease Kunitz-type inhibitor. Amblyomin-X induced tumor mass regression and decreased number of metastatic events in a B16F10 murine melanoma model. Alterations on expression of several genes related to cell cycle were observed when two tumor cell lines were treated with Amblyomin-X. PSMB2, which encodes a proteasome subunit, was differentially expressed, in agreement to inhibition of proteasomal activity in both cell lines. In conclusion, our results indicate that Amblyomin-X selectively acts on tumor cells by inducing apoptotic cell death, possibly by targeting the ubiquitin-proteasome system.

The search for molecules with therapeutic potential against cancer is a crucial issue to reduce the amount of death in human population around the world. Previously, we showed that crotamine, a natural polypeptide from the venom of the rattlesnake Crotalus durissus terrificus, has ability to induce cancer cells apoptosis in vitro, as well as, delay and inhibit melanomas formation in vivo in mice. In order to reduce crotamine length and toxicity, while maintaining its anti-cancer properties, two short peptides were designed and synthetized. Such short peptides represent an intermediate potential step toward to the development of drugs targeted cancer death. The aim of present study was to analyze pro-apoptotic activity of both of these peptides (1 and 2), composed by crotamine (crot.) and BAX (pro-apoptotic protein from BCL2 family) both derived sequences in melanoma and breast cancer cells in vitro. Melanoma and breast cancer cells (MEL-85, A2058, B16-F10 and SKBR3) were used. The MTT assay was performed after addition of both of these peptides used in different concentrations into cancer cells. The expression of proteins (PARP, Cleaved - Caspase 3, Caspase 3, Phospho - BAD) was evaluated by western blotting. Flow cytometry was performed to evaluate the cell cycle. The mitochondria potential was also verified before and after peptides addition. Morphologic changes, such as, detachment from substrate, cell contraction, loss of inter-cell elongations and several others effects were observed in cancer cells after 24 hours of incubation with peptides. At that time, the peptides exhibit cytotoxic activity as verified by MTT assay. Cell cycle analyses demonstrated that they decrease the timing of G2/M phases, while increasing a sub-G0/G1 phase. Unexpectedly, both peptides increase mitochondria potential of cancer cells, when compared with control cultures (without addition of peptides). Increase of expression pro-apoptotic proteins, such as, cleaved Caspase 3 and PARP was evidenced in cancer cells after addition of peptide -1, while Phospho-BAD was increased after addition of peptide - 2. Our data suggest that both peptides are efficient to trigger cell death in melanoma and breast cancer cells in vitro. Crot alone was not able to induce such changes in cancer cells. Citation Format: Nicole Caroline Mambelli, Paulo Luis De-Sá-Júnior, Jr., Adilson Kleber Ferreira, Ricardo Alexandre Azevedo, Diana Aparecida Câmara, Irina Kerkis, Sr.. Crotamine derived fusion short-peptides and their effect on melanoma and breast cancer cells cultured in vitro. [abstract]. In: Proceedings of the AACR Precision Medicine Series: Drug Sensitivity and Resistance: Improving Cancer Therapy; Jun 18-21, 2014; Orlando, FL. Philadelphia (PA): AACR; Clin Cancer Res 2015;21(4 Suppl): Abstract nr A50.