title: Myeloid-derived suppressor cells and associated events in urethane-induced lung cancer.
abstract: OBJECTIVE
  Myeloid-derived suppressor cells contribute to the immunosuppressive microenvironment during tumor development and limit the efficacy of cancer immunotherapy. Identifying myeloid-derived suppressor cells and associated factors is the first step in creating strategies to reverse the suppressive effects of these cells on the immune system.
  
  
  METHODS
  To induce lung cancer, we administered 2 doses of urethane to BALB/c mice and observed these animals for 120 days. After this period, we evaluated the percentage of myeloid-derived suppressor cells in the blood, lung and bone marrow. The expression of alpha-smooth muscle actin, transforming growth factor-β, Toll-like receptor 2, Toll-like receptor 4, and interleukin-6 was also determined in the lung tissue.
  
  
  RESULTS
  Myeloid-derived suppressor cells were increased in all evaluated tissues after lung cancer development in association with increased Toll-like receptor 4 expression and decreased interleukin-6 expression in the lung. We observed alpha-smooth muscle actin and transforming growth factor-β expression in lung nodules.
  
  
  CONCLUSIONS
  We believe that the early diagnosis of cancer through determining the blood levels of myeloid-derived suppressor cells followed by the depletion of these cells should be further investigated as a possible approach for cancer treatment.
authors.affiliation: Federal University of São Paulo, Immunology Division, São Paulo/SP, Brazil.
authors.forename: Daniela
authors.initials: D
authors.lastname: Teixeira
authors.forename: Joaquim Soares de
authors.initials: JS
authors.lastname: Almeida
authors.forename: Bruna
authors.initials: B
authors.lastname: Visniauskas
authors.forename: Guiomar Nascimento
authors.initials: GN
authors.lastname: Gomes
authors.forename: Aparecida Emiko
authors.initials: AE
authors.lastname: Hirata
authors.forename: Valquiria
authors.initials: V
authors.lastname: Bueno
mesh_terms: D000199:Actins / Q000378:metabolism; D000818:Animals; D015153:Blotting, Western; D002273:Carcinogens; D005434:Flow Cytometry; D007150:Immunohistochemistry; D015850:Interleukin-6 / Q000378:metabolism; D008168:Lung / Q000187:drug effects / Q000473:pathology; D008175:Lung Neoplasms / Q000139:chemically induced / Q000276:immunology / Q000473:pathology*; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D022423:Myeloid Cells / Q000276:immunology / Q000473:pathology*; D013997:Time Factors; D051197:Toll-Like Receptor 4 / Q000378:metabolism; D014520:Urethane
chemical_list: D000199:Actins; D002273:Carcinogens; D015850:Interleukin-6; C493487:Tlr4 protein, mouse; D051197:Toll-Like Receptor 4; C544013:alpha-smooth muscle actin, mouse; C577686:interleukin-6, mouse; D014520:Urethane