title: Antiangiogenic and antitumor effects of Trypanosoma cruzi Calreticulin.
abstract: BACKGROUND
  In Latin America, 18 million people are infected with Trypanosoma cruzi, the agent of Chagas' disease, with the greatest economic burden. Vertebrate calreticulins (CRT) are multifunctional, intra- and extracellular proteins. In the endoplasmic reticulum (ER) they bind calcium and act as chaperones. Since human CRT (HuCRT) is antiangiogenic and suppresses tumor growth, the presence of these functions in the parasite orthologue may have consequences in the host/parasite interaction. Previously, we have cloned and expressed T. cruzi calreticulin (TcCRT) and shown that TcCRT, translocated from the ER to the area of trypomastigote flagellum emergence, promotes infectivity, inactivates the complement system and inhibits angiogenesis in the chorioallantoid chicken egg membrane. Most likely, derived from these properties, TcCRT displays in vivo inhibitory effects against an experimental mammary tumor.
  
  
  RESULTS
  TcCRT (or its N-terminal vasostatin-like domain, N-TcCRT) a) Abrogates capillary growth in the ex vivo rat aortic ring assay, b) Inhibits capillary morphogenesis in a human umbilical vein endothelial cell (HUVEC) assay, c) Inhibits migration and proliferation of HUVECs and the human endothelial cell line Eahy926. In these assays TcCRT was more effective, in molar terms, than HuCRT: d) In confocal microscopy, live HUVECs and EAhy926 cells, are recognized by FITC-TcCRT, followed by its internalization and accumulation around the host cell nuclei, a phenomenon that is abrogated by Fucoidin, a specific scavenger receptor ligand and, e) Inhibits in vivo the growth of the murine mammary TA3 MTXR tumor cell line.
  
  
  CONCLUSIONS
  We describe herein antiangiogenic and antitumor properties of a parasite chaperone molecule, specifically TcCRT. Perhaps, by virtue of its capacity to inhibit angiogenesis (and the complement system), TcCRT is anti-inflammatory, thus impairing the antiparasite immune response. The TcCRT antiangiogenic effect could also explain, at least partially, the in vivo antitumor effects reported herein and the reports proposing antitumor properties for T. cruzi infection.
authors.affiliation: Institute of Biomedical Sciences, Faculty of Medicine, University of Chile, Santiago, Chile.
authors.forename: Nandy C
authors.initials: NC
authors.lastname: López
authors.forename: Carolina
authors.initials: C
authors.lastname: Valck
authors.forename: Galia
authors.initials: G
authors.lastname: Ramírez
authors.forename: Margarita
authors.initials: M
authors.lastname: Rodríguez
authors.forename: Carolina
authors.initials: C
authors.lastname: Ribeiro
authors.forename: Juana
authors.initials: J
authors.lastname: Orellana
authors.forename: Ismael
authors.initials: I
authors.lastname: Maldonado
authors.forename: Adriana
authors.initials: A
authors.lastname: Albini
authors.forename: Daniel
authors.initials: D
authors.lastname: Anacona
authors.forename: David
authors.initials: D
authors.lastname: Lemus
authors.forename: Lorena
authors.initials: L
authors.lastname: Aguilar
authors.forename: Wilhelm
authors.initials: W
authors.lastname: Schwaeble
authors.forename: Arturo
authors.initials: A
authors.lastname: Ferreira
mesh_terms: D020533:Angiogenesis Inhibitors / Q000302:isolation & purification / Q000494:pharmacology*; D000818:Animals; D000970:Antineoplastic Agents / Q000302:isolation & purification / Q000494:pharmacology*; D037282:Calreticulin / Q000302:isolation & purification / Q000494:pharmacology*; D002478:Cells, Cultured; D042783:Endothelial Cells / Q000187:drug effects; D006801:Humans; D008325:Mammary Neoplasms, Experimental / Q000188:drug therapy / Q000473:pathology; D051379:Mice; D009924:Organ Culture Techniques; D051381:Rats; D017207:Rats, Sprague-Dawley; D014349:Trypanosoma cruzi / Q000737:chemistry*
chemical_list: D020533:Angiogenesis Inhibitors; D000970:Antineoplastic Agents; D037282:Calreticulin