title: Cisplatin augments cytotoxic T-lymphocyte-mediated antitumor immunity in poorly immunogenic murine lung cancer.
abstract: OBJECTIVE
  Many tumors are poorly immunogenic and resistant to cytotoxic T-lymphocyte-mediated cell lysis. Because cisplatin has been demonstrated to increase tumor cell Fas receptor expression, we hypothesized that cisplatin will enhance cytotoxic T-lymphocyte tumor cell killing and augment the antitumor effect of an active immunotherapy strategy in a poorly immunogenic murine lung cancer model.
  
  
  METHODS
  Lewis lung carcinoma cells were exposed to cisplatin in vitro, and Fas receptor expression and apoptosis in response to an agonistic anti-Fas antibody were quantified using flow cytometry. Wild-type and Fas ligand-deficient mice bearing Lewis lung carcinoma flank tumors were then treated with intraperitoneal cisplatin as well as an intratumoral injection of an adenovirus gene transfer vector encoding CD40 ligand. End points included tumor size, animal survival, and Fas expression (determined using immunofluorescence). Cytotoxicity assays were performed using splenocytes from adenovirus gene transfer vector encoding CD40 ligand-treated animals as effectors and cisplatin-treated Lewis lung carcinoma cells as targets.
  
  
  RESULTS
  Cisplatin induced heightened expression of Fas receptor on Lewis lung carcinoma cells in vitro and in vivo and enhanced apoptosis in cells exposed to an agonistic anti-Fas antibody. In vivo, the combination of 1 dose of intraperitoneal cisplatin and intratumoral adenovirus gene transfer vector encoding CD40 ligand inhibited tumor growth and prolonged survival compared with adenovirus gene transfer vector encoding CD40 ligand alone, resulting in a higher cure rate. This effect was lost in Fas ligand-deficient mice. Splenocytes from adenovirus gene transfer vector encoding CD40 ligand-treated wild-type mice lysed cisplatin-treated Lewis lung carcinoma cells more efficiently than untreated Lewis lung carcinoma cells, an effect lost in splenocytes from Fas ligand-deficient mice.
  
  
  CONCLUSIONS
  Cisplatin augments the antitumor effect of a cytotoxic T-lymphocyte-mediated immunotherapy strategy, resulting in a higher cure rate than seen with immunotherapy alone. This effect is associated with the enhanced ability of cytotoxic T lymphocytes to lyse tumor cells that have been exposed to cisplatin through Fas/Fas ligand interactions.
authors.affiliation: Department of Cardiothoracic Surgery, Weill Medical College of Cornell University, New York, NY 10021, USA.
authors.forename: Robert E
authors.initials: RE
authors.lastname: Merritt
authors.forename: Ali
authors.initials: A
authors.lastname: Mahtabifard
authors.forename: Reiko E
authors.initials: RE
authors.lastname: Yamada
authors.forename: Ronald G
authors.initials: RG
authors.lastname: Crystal
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Korst
mesh_terms: D000256:Adenoviridae; D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology; D023201:CD40 Ligand; D018827:Carcinoma, Lewis Lung / Q000276:immunology* / Q000628:therapy*; D002945:Cisplatin / Q000494:pharmacology*; D005260:Female; D005434:Flow Cytometry; D005455:Fluorescent Antibody Technique; D018014:Gene Transfer Techniques; D005822:Genetic Vectors; D016219:Immunotherapy, Adoptive / Q000379:methods*; D007274:Injections, Intraperitoneal; D051379:Mice; D008810:Mice, Inbred C57BL; D011336:Probability; D012680:Sensitivity and Specificity; D018709:Statistics, Nonparametric; D015996:Survival Rate; D013602:T-Lymphocytes, Cytotoxic / Q000187:drug effects* / Q000276:immunology; D014407:Tumor Cells, Cultured; D015854:Up-Regulation; D019014:fas Receptor / Q000187:drug effects / Q000276:immunology
chemical_list: D019014:fas Receptor; D023201:CD40 Ligand; D002945:Cisplatin