title: Glutathione and Bcl-2 targeting facilitates elimination by chemoradiotherapy of human A375 melanoma xenografts overexpressing bcl-xl, bcl-2, and mcl-1.
abstract: BACKGROUND
  Bcl-2 is believed to contribute to melanoma chemoresistance. However, expression of Bcl-2 proteins may be different among melanomas. Thus correlations among expression of Bcl-2-related proteins and in vivo melanoma progression, and resistance to combination therapies, was investigated.
  
  
  METHODS
  Human A375 melanoma was injected s.c. into immunodeficient nude mice. Protein expression was studied in tumor samples obtained by laser microdisection. Transfection of siRNA or ectopic overexpression were applied to manipulate proteins which are up- or down-regulated, preferentially, during melanoma progression. Anti-bcl-2 antisense oligonucleotides and chemoradiotherapy (glutathione-depleting agents, paclitaxel protein-binding particles, daunorubicin, X rays) were administered in combination.
  
  
  RESULTS
  In vivo A375 cells down-regulated pro-apoptotic bax expression; and up-regulated anti-apoptotic bcl-2, bcl-xl, and mcl-1, however only Bcl-2 appeared critical for long-term tumor cell survival and progression in vivo. Reduction of Bcl-2, combined with partial therapies, decreased melanoma growth. But only Bcl-2 targeting plus the full combination of chemoradiotherapy eradicated A375 melanoma, and led to long-term survival (> 120 days) without recurrence in 80% of mice. Tumor regression was not due to immune stimulation. Hematology and clinical chemistry data were within accepted clinical toxicities.
  
  
  CONCLUSIONS
  Strategies to target Bcl-2, may increase the effectiveness of antitumor therapies against melanomas overexpressing Bcl-2 and likely other Bcl-2-related antiapoptotic proteins.
authors.affiliation: Department of Physiology, University of Valencia, Valencia, Spain.
authors.forename: Salvador
authors.initials: S
authors.lastname: Mena
authors.forename: María L
authors.initials: ML
authors.lastname: Rodriguez
authors.forename: Angel
authors.initials: A
authors.lastname: Ortega
authors.forename: Sonia
authors.initials: S
authors.lastname: Priego
authors.forename: Elena
authors.initials: E
authors.lastname: Obrador
authors.forename: Miguel
authors.initials: M
authors.lastname: Asensi
authors.forename: Ignacio
authors.initials: I
authors.lastname: Petschen
authors.forename: Miguel
authors.initials: M
authors.lastname: Cerdá
authors.forename: Bob D
authors.initials: BD
authors.lastname: Brown
authors.forename: José M
authors.initials: JM
authors.lastname: Estrela
mesh_terms: D000068196:Albumin-Bound Paclitaxel; D000418:Albumins / Q000494:pharmacology / Q000627:therapeutic use; D000818:Animals; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D059248:Chemoradiotherapy; D016207:Cytokines / Q000097:blood; D003630:Daunorubicin / Q000494:pharmacology / Q000627:therapeutic use; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D020868:Gene Silencing / Q000187:drug effects; D005978:Glutathione / Q000378:metabolism*; D006801:Humans; D007555:Isoxazoles / Q000494:pharmacology / Q000627:therapeutic use; D008545:Melanoma / Q000097:blood / Q000235:genetics / Q000473:pathology / Q000628:therapy*; D051379:Mice; D008819:Mice, Nude; D064549:Myeloid Cell Leukemia Sequence 1 Protein; D017239:Paclitaxel / Q000494:pharmacology / Q000627:therapeutic use; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism*; D012074:Remission Induction; D016019:Survival Analysis; D023041:Xenograft Model Antitumor Assays; D051020:bcl-X Protein / Q000378:metabolism*
chemical_list: D000068196:Albumin-Bound Paclitaxel; D000418:Albumins; D016207:Cytokines; D007555:Isoxazoles; C579094:Mcl1 protein, mouse; D064549:Myeloid Cell Leukemia Sequence 1 Protein; D019253:Proto-Oncogene Proteins c-bcl-2; D051020:bcl-X Protein; D005978:Glutathione; C006303:acivicin; D017239:Paclitaxel; D003630:Daunorubicin