title: The natural cell-penetrating peptide crotamine targets tumor tissue in vivo and triggers a lethal calcium-dependent pathway in cultured cells.
abstract: Our goal was to demonstrate the in vivo tumor specific accumulation of crotamine, a natural peptide from the venom of the South American rattlesnake Crotalus durissus terrificus, which has been characterized by our group as a cell penetrating peptide with a high specificity for actively proliferating cells and with a concentration-dependent cytotoxic effect. Crotamine cytotoxicity has been shown to be dependent on the disruption of lysosomes and subsequent activation of intracellular proteases. In this work, we show that the cytotoxic effect of crotamine also involves rapid intracellular calcium release and loss of mitochondrial membrane potential as observed in real time by confocal microscopy. The intracellular calcium overload induced by crotamine was almost completely blocked by thapsigargin. Microfluorimetry assays confirmed the importance of internal organelles, such as lysosomes and the endoplasmic reticulum, as contributors for the intracellular calcium increase, as well as the extracellular medium. Finally, we demonstrate here that crotamine injected intraperitoneally can efficiently target remote subcutaneous tumors engrafted in nude mice, as demonstrated by a noninvasive optical imaging procedure that permits in vivo real-time monitoring of crotamine uptake into tumor tissue. Taken together, our data indicate that the cytotoxic peptide crotamine can be used potentially for a dual purpose: to target and detect growing tumor tissues and to selectively trigger tumor cell death.
authors.affiliation: Grupo de Estudos em Odontologia,  Universidade Bandeirante de São Paulo  (UNIBAN), São Paulo, SP, Brazil.
authors.forename: Fabio D
authors.initials: FD
authors.lastname: Nascimento
authors.forename: Lucie
authors.initials: L
authors.lastname: Sancey
authors.forename: Alexandre
authors.initials: A
authors.lastname: Pereira
authors.forename: Claire
authors.initials: C
authors.lastname: Rome
authors.forename: Vitor
authors.initials: V
authors.lastname: Oliveira
authors.forename: Eduardo B
authors.initials: EB
authors.lastname: Oliveira
authors.forename: Helena B
authors.initials: HB
authors.lastname: Nader
authors.forename: Tetsuo
authors.initials: T
authors.lastname: Yamane
authors.forename: Irina
authors.initials: I
authors.lastname: Kerkis
authors.forename: Ivarne L S
authors.initials: IL
authors.lastname: Tersariol
authors.forename: Jean-Luc
authors.initials: JL
authors.lastname: Coll
authors.forename: Mirian A F
authors.initials: MA
authors.lastname: Hayashi
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents; D016466:CHO Cells; D002118:Calcium / Q000378:metabolism*; D020013:Calcium Signaling / Q000187:drug effects*; D016923:Cell Death / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D057846:Cell-Penetrating Peptides / Q000008:administration & dosage* / Q000493:pharmacokinetics; D006224:Cricetinae; D003412:Cricetulus; D003435:Crotalid Venoms / Q000008:administration & dosage* / Q000493:pharmacokinetics; D017839:Crotalus; D004721:Endoplasmic Reticulum / Q000187:drug effects / Q000378:metabolism; D005434:Flow Cytometry; D057809:HEK293 Cells; D006801:Humans; D007274:Injections, Intraperitoneal; D008247:Lysosomes / Q000187:drug effects / Q000378:metabolism; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects; D051379:Mice; D008819:Mice, Nude; D018613:Microscopy, Confocal; D009369:Neoplasms / Q000175:diagnosis / Q000188:drug therapy / Q000378:metabolism*; D019284:Thapsigargin / Q000494:pharmacology; D014407:Tumor Cells, Cultured; D023041:Xenograft Model Antitumor Assays
chemical_list: D000970:Antineoplastic Agents; D057846:Cell-Penetrating Peptides; D003435:Crotalid Venoms; D019284:Thapsigargin; C010563:crotamine; D002118:Calcium