title: Comparison between the antiproliferative effect and intracellular glutathione depletion induced by Casiopeína IIgly and cisplatin in murine melanoma B16 cells.
abstract: BACKGROUND
  Casiopeína IIgly (Cas IIgly) [Cu(4,7-dimethyl-1,10-phenanthroline)(glycinate)]NO(3) induce oxidative damage in different human tumour cell strains, as the known anticancer agent cisplatin (CDDP) does.
  
  
  OBJECTIVE
  To compare glutathione (GSH) depletion induced by Cas IIgly and CDDP in murine melanoma B16 cells and its relationship with their antiproliferative effect.
  
  
  METHODS
  Cell growth was determined according to the sulforhodamine B assay. Intracellular GSH levels were measured by the reduction of Ellman's reagent (DTNB).
  
  
  RESULTS
  Cas IIgly IC50 in B16 cells was 54.5 μM (24.21 μg/mL), which depleted GSH from 1092 to 585 ng per million cells in a 30 min incubation period. In the other hand, CDDP was less toxic at the same conditions with an IC50 equal to 197.76 μM (59.33 μg/mL), and depleted GSH to 50% of the normal only after a longer exposure period (4h). The addition of 1.8mM ascorbic acid (Asc) or 1mM buthionine sulfoximine (BSO) enhanced Cas IIgly toxicity, whereas it was prevented by 100 U/mL catalase. BSO sensitised B16 cells to CDDP, but neither Asc or catalase modified CDDP effects.
  
  
  CONCLUSIONS
  The antiproliferative effect of both drugs correlated to intracellular GSH levels. Unlike CDDP, GSH depletion induced by Cas IIgly occurs earlier, it is enhanced by ascorbic acid and preventable by catalase. Redox cycles, feasible only with Cas IIgly, may be an important difference in their mode of action.
authors.affiliation: Unidad de Experimentación Animal, Facultad de Química, Universidad Nacional Autónoma de México, Z.P. 04510 Mexico City, Mexico; Laboratorio de Farmacología, Instituto Nacional de Pediatría, SSA Mexico City Z.P. 04530, Mexico.
authors.forename: Radamés
authors.initials: R
authors.lastname: Alemón-Medina
authors.forename: María Elena
authors.initials: ME
authors.lastname: Bravo-Gómez
authors.forename: María Isabel
authors.initials: MI
authors.lastname: Gracia-Mora
authors.forename: Lena
authors.initials: L
authors.lastname: Ruiz-Azuara
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology*; D001205:Ascorbic Acid / Q000494:pharmacology; D002374:Catalase / Q000494:pharmacology; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D002945:Cisplatin / Q000494:pharmacology*; D005978:Glutathione / Q000187:drug effects / Q000378:metabolism; D020128:Inhibitory Concentration 50; D008546:Melanoma, Experimental / Q000188:drug therapy* / Q000473:pathology; D051379:Mice; D009942:Organometallic Compounds / Q000494:pharmacology*; D013997:Time Factors
chemical_list: D000970:Antineoplastic Agents; D009942:Organometallic Compounds; C505569:casiopeina II-glycine; D002374:Catalase; D005978:Glutathione; D001205:Ascorbic Acid; D002945:Cisplatin