title: Purification and partial characterization of a ribosome-inactivating protein from the latex of Euphorbia trigona Miller with cytotoxic activity toward human cancer cell lines.
abstract: BACKGROUND
  The objective of this study is to investigate the cytotoxic activity of three isolectins purified from the latex of Euphorbia trigona Miller.
  
  
  OBJECTIVE
  Among lectins are the ribosome-inactivating proteins (RIPs), which are potent inhibitors of protein synthesis in cells and in cell-free systems.
  
  
  RESULTS
  Three isolectins, ETR1, ETR2 and ETR3, were purified by anion exchange chromatography. Both ETR1 and ETR3 yielded a single band on SDS-PAGE under reducing conditions, corresponding to a molecular weight of 32 g mol(-1), while ETR2 yielded two bands corresponding to 31 and 33 g mol(-1). When non-reducing conditions were used molecular weight decreased, indicating the presence of intrachain disulfide bonds. Size-exclusion chromatography revealed proteins of apparent molecular weight of 59-63 g mol(-1), suggesting a dimeric nature, with subunits not being held together by disulfide linkage. ETR1, ETR2 and ETR3 hemagglutinated human, sheep and rat erythrocytes and this hemagglutination was specifically inhibited by galactose and its derivatives. The lectins studied were thermostable up to 60 °C and their observed activity was maintained across pH range 5-12. These lectins, from the latex of Euphorbia trigona, are potent inhibitors of eukaryotic protein synthesis in a cell-free system. Flow cytometry analysis revealed the antiproliferative activity of them toward A549, HeLa, H116, HL-60 cell lines.
  
  
  CONCLUSIONS
  Euphorbia trigona isolectins are RIPs with cytotoxic activity toward human cancer cell lines.
authors.affiliation: Neiker-Tecnalia, Biotechnology Department, Arkaute Agrifood Campus, PO Box 46, 01080 Vitoria-Gasteiz, Álava, Spain.
authors.forename: Judith
authors.initials: J
authors.lastname: Villanueva
authors.affiliation: University Institute of Oncology of Asturias and Department of Functional Biology, University of Oviedo, Julian Claveria s/n, Oviedo 33006, Spain.
authors.forename: Luis Manuel
authors.initials: LM
authors.lastname: Quirós
authors.affiliation: Neiker-Tecnalia, Biotechnology Department, Arkaute Agrifood Campus, PO Box 46, 01080 Vitoria-Gasteiz, Álava, Spain . Electronic address: scdelatorre@neiker.net.
authors.forename: Sonia
authors.initials: S
authors.lastname: Castañón
mesh_terms: D000818:Animals; D000972:Antineoplastic Agents, Phytogenic / Q000302:isolation & purification / Q000494:pharmacology; D045744:Cell Line, Tumor / Q000187:drug effects; D002850:Chromatography, Gel; D004591:Electrophoresis, Polyacrylamide Gel; D004912:Erythrocytes; D028481:Euphorbia / Q000737:chemistry*; D006384:Hemagglutination / Q000187:drug effects; D006386:Hemagglutination Tests; D006801:Humans; D007840:Latex / Q000737:chemistry*; D008970:Molecular Weight; D037121:Plant Lectins / Q000302:isolation & purification / Q000494:pharmacology*; D014176:Protein Biosynthesis / Q000187:drug effects; D051381:Rats; D012270:Ribosomes / Q000187:drug effects*; D012756:Sheep
chemical_list: D000972:Antineoplastic Agents, Phytogenic; D007840:Latex; D037121:Plant Lectins
keywords: Antitumoral; Cytotoxic; Hemagglutination; Lectin; Ribosome-inactivating proteins (RIPs)