title: H₂O₂ production within tumor microenvironment inversely correlated with infiltration of CD56(dim) NK cells in gastric and esophageal cancer: possible mechanisms of NK cell dysfunction.
abstract: Human NK cells can be divided into two subsets, CD56(dim)CD16(+)NK and CD56(bright)CD16(-)NK cells, based on their expression of CD56 and CD16. In the present study, we analyzed the relationship between CD56(dim)/CD56(bright) NK cells and H₂O₂ in tumor-infiltrating NK cells in patients with gastric (n = 50) and esophageal (n = 35) cancer. The ratio of CD56(dim) NK cells infiltrating tumors gradually decreased according to disease progression. H₂O₂ was abundantly produced within tumor microenvironments, and there was an inverse correlation between CD56(dim) NK cell infiltration and H₂O₂ production. CD56(dim) NK cells are more sensitive to apoptosis induced by physiological levels of H₂O₂ than CD56(bright) NK cells. Furthermore, the exposure of NK cells to H₂O₂ resulted in the impairment of ADCC activity. In conclusion, H₂O₂ produced within tumor microenvironments inversely correlated with the infiltration of CD56(dim) NK cells, possibly due to their preferentially induced cell death. These observations may explain one of the mechanisms behind NK cell dysfunction frequently observed in tumor microenvironments.
authors.affiliation: First Department of Surgery, University of Yamanashi, 1110 Shimokato, Chuo-city, Yamanashi 409-3898, Japan.
authors.forename: Shinichirou
authors.initials: S
authors.lastname: Izawa
authors.forename: Koji
authors.initials: K
authors.lastname: Kono
authors.forename: Kousaku
authors.initials: K
authors.lastname: Mimura
authors.forename: Yoshihiko
authors.initials: Y
authors.lastname: Kawaguchi
authors.forename: Mitsuaki
authors.initials: M
authors.lastname: Watanabe
authors.forename: Takanori
authors.initials: T
authors.lastname: Maruyama
authors.forename: Hideki
authors.initials: H
authors.lastname: Fujii
mesh_terms: D000368:Aged; D019002:CD56 Antigen / Q000096:biosynthesis / Q000276:immunology; D002294:Carcinoma, Squamous Cell / Q000276:immunology / Q000378:metabolism / Q000473:pathology; D002469:Cell Separation; D004938:Esophageal Neoplasms / Q000276:immunology* / Q000378:metabolism / Q000473:pathology; D005260:Female; D005434:Flow Cytometry; D006801:Humans; D006861:Hydrogen Peroxide / Q000378:metabolism*; D007150:Immunohistochemistry; D007694:Killer Cells, Natural / Q000276:immunology*; D016131:Lymphocyte Subsets / Q000276:immunology* / Q000378:metabolism; D016246:Lymphocytes, Tumor-Infiltrating / Q000276:immunology; D008297:Male; D009367:Neoplasm Staging; D013274:Stomach Neoplasms / Q000276:immunology* / Q000378:metabolism / Q000473:pathology; D059016:Tumor Microenvironment / Q000276:immunology*
chemical_list: D019002:CD56 Antigen; D006861:Hydrogen Peroxide