Amblyomin-X induces ER stress, mitochondrial dysfunction, and caspase activation in human melanoma and pancreatic tumor cell

During the last two decades, new insights into proteasome function and its role in several human diseases made it a potential therapeutic target. In this context, Amblyomin-X is a Kunitz-type FXa inhibitor similar to endogenous tissue factor pathway inhibitor (TFPI) and is a novel proteasome inhibitor. Herein, we have demonstrated Amblyomin-X cytotoxicity to different tumor cells lines such as pancreatic (Panc1, AsPC1BxPC3) and melanoma (SK-MEL-5 and SK-MEL-28). Of note, Amblyomin-X was not cytotoxic to normal human fibroblast cells. In addition, Amblyomin-X promoted accumulation of ER stress markers (GRP78 and GADD153) in sensitive (SK-MEL-28) and bortezomib-resistant (Mia-PaCa-2) tumor cells. The intracellular calcium concentration [Ca2+] (i) was slightly modulated in human tumor cells (SK-MEL-28 and Mia-PaCa-2) after 24 h of Amblyomin-X treatment. Furthermore, Amblyomin-X induced mitochondrial dysfunction, cytochrome-c release, PARP cleavage, and activation of caspase cascade in both human tumor (SK-MEL-28 and Mia-PaCa-2) cells. These investigations might help in further understanding of the antitumor properties of Amblyomin-X.Sao Paulo Research Foundation (FAPESP)National Council of Technological and Scientific Development (CNPq, INCTTox)Coordination of Improvement of Higher Education Personnel (CAPES)Uniao Quimica Farmaceutica NacionalButantan Inst, Biochem & Biophys Lab, Ave Vital Brazil 1500, BR-05503900 Sao Paulo, SP, BrazilUniv Fed Sao Paulo, Dept Biochem, Sao Paulo, SP, BrazilUniv Sao Paulo, Inst Chem, Dept Biochem, Sao Paulo, BrazilUniv Sao Paulo, Sch Med, Expt Oncol Med Invest Lab, LIM 24, Sao Paulo, SP, BrazilUniv Fed Sao Paulo, Dept Biochem, Sao Paulo, SP, BrazilFAPESP: 2010/52669-3FAPESP: 2010/07958-7FAPESP: 2011/05969-4FAPESP: CAT/CEPID 1998/14307-9FAPESP: CETICs 2013/07467-1Web of Scienc

Tick salivary gland as potential natural source for the discovery of promising antitumor drug candidates

Nowadays, the relationship between cancer blood coagulation is well established. Regarding biodiversity and bioprospection, the tick biology has become quite attractive natural source for coagulation inhibitors, since its saliva has a very rich variety of bioactive molecules. For instance, a Kunitz-type FXa inhibitor, named Amblyomin-X, was found through transcriptome of the salivary gland of the Amblyomma cajennense. tick. This TFPI-like inhibitor, after obtained as recombinant protein, has presented anticoagulant, antigionenic, and antitumor properties. Although its effects on blood coagulation could be relevant for antitumor effect, Amblyomin-X acts by non-hemostatic mechanisms, such as proteasome inhibition and autophagy inhibition. Notably, cytotoxicity was not observed on non-tumor cells treated with this protein, suggesting some selectivity for tumor cells. Considering the current efforts in order to develop effective anticancer therapies, the findings presented in this review strongly suggest Amblyomin-X as a promising novel antitumor drug candidate. (C) 2015 Elsevier Masson SAS. All rights reserved.Sao Paulo Research Foundation (FAPESP)Butantan Inst, Biochem & Biophys Lab, BR-05503900 Sao Paulo, SP, BrazilUniv Fed Sao Paulo, Dept Biochem, Sao Paulo, SP, BrazilUniv Fed Sao Paulo, Dept Biochem, Sao Paulo, SP, BrazilFAPESP: 2010/52669-3FAPESP: 2010/07958-7FAPESP: 2011/05969-4FAPESP CAT/CEPID: 1998/14307-9FAPESP CETICs: 2013/07467-1Web of Scienc