title: Immunotherapeutic effect of Concholepas hemocyanin in the murine bladder cancer model: evidence for conserved antitumor properties among hemocyanins.
abstract: OBJECTIVE
  We determined the antitumor properties of a newly available hemocyanin obtained from the Chilean gastropod Concholepas concholepas (Biosonda Corp., Santiago, Chile) in a syngeneic heterotopic mouse bladder carcinoma model. Since keyhole limpet hemocyanin (Pierce, Rockford, Illinois) is used increasingly in biomedicine as a carrier for vaccines and an immunotherapeutic agent for bladder transitional cell carcinoma, there is a growing interest in finding new substances that share its potent immunomodulatory properties. Considering that keyhole limpet hemocyanin and Concholepas concholepas hemocyanin differ significantly, it was not possible to predict a priori the antitumor properties of Concholepas concholepas hemocyanin.
  
  
  METHODS
  C3H/He mice were primed with Concholepas concholepas hemocyanin before subcutaneous implantation of mouse bladder tumor-2 cells. Treatment consisted of a subcutaneous dose of Concholepas concholepas hemocyanin (1 mg or 100 mug) at different intervals after implantation. Keyhole limpet hemocyanin and phosphate buffered saline served as positive and negative controls, respectively. In addition, experiments were designed to determine which elements of the immune response were involved in its adjuvant immunostimulatory effect.
  
  
  RESULTS
  Mice treated with Concholepas concholepas hemocyanin showed a significant antitumor effect, as demonstrated by decreased tumor growth and incidence, prolonged survival and lack of toxic effects. These effects were similar to those achieved with keyhole limpet hemocyanin. We found that each hemocyanin increased natural killer cell activity but the effect of Concholepas concholepas hemocyanin was stronger. Analysis of serum from treated mice showed an increased interferon-gamma and low interleukin-4, which correlated with antibody isotypes, confirming that hemocyanins induce a T helper type 1 cytokine profile.
  
  
  CONCLUSIONS
  To our knowledge our results are the first demonstration of the antitumor effect of a hemocyanin other than keyhole limpet hemocyanin. They suggest that this is an ancient conserved immunogenic mechanism shared by those hemocyanins that is able to enhance T helper type 1 immunity and lead to antitumor activity. Therefore, Concholepas concholepas hemocyanin may be an alternative candidate for providing safe and effective immunotherapy for human superficial bladder cancer.
authors.affiliation: Department of Research and Development, Biosonda Corporation, Avenida Alcalde Eduardo Castillo Velasco 2902, Nuñoa, Santiago, Chile.
authors.forename: Bruno
authors.initials: B
authors.lastname: Moltedo
authors.forename: Fernando
authors.initials: F
authors.lastname: Faunes
authors.forename: Denise
authors.initials: D
authors.lastname: Haussmann
authors.forename: Pablo
authors.initials: P
authors.lastname: De Ioannes
authors.forename: Alfredo E
authors.initials: AE
authors.lastname: De Ioannes
authors.forename: Javier
authors.initials: J
authors.lastname: Puente
authors.forename: María Inés
authors.initials: MI
authors.lastname: Becker
mesh_terms: D000818:Animals; D002295:Carcinoma, Transitional Cell / Q000276:immunology / Q000628:therapy*; D003602:Cytotoxicity, Immunologic; D004195:Disease Models, Animal; D049851:Gastropoda; D006433:Hemocyanins / Q000276:immunology / Q000627:therapeutic use*; D051379:Mice; D008809:Mice, Inbred C3H; D014407:Tumor Cells, Cultured; D001749:Urinary Bladder Neoplasms / Q000276:immunology / Q000628:therapy*
chemical_list: D006433:Hemocyanins