title: Combinatorial cytotoxicity of gemcitabine and cytokine-activated killer cells in hepatocellular carcinoma via the NKG2D-MICA/B system.
abstract: OBJECTIVE
  Natural-killer group 2, member D (NKG2D) is an activating receptor on natural killer cells and activated T-cells, designated cytokine-activated killer (CAK) cells here. The MHC class I chain-related A and B (MICA and MICB, respectively) are ligands of NKG2D and are expressed on various human tumor cells, including hepatocellular carcinoma (HCC) cells. Here, we investigate whether gemcitabine, a chemotherapeutic agent, affects MICA/B expression in HCC.
  
  
  METHODS
  We used ELISA, RT-PCR and adherent target detachment assays to determine expression of MICA/B in HepG2 HCC cells and the level of cellular cytotoxicity generated by treatment with gemcitabine and/or CAK cells.
  
  
  RESULTS
  Surface expression of MICA/B was evident after gemcitabine treatment, and MICB-specific mRNA was up-regulated. Pre-treatment with gemcitabine and subsequent exposure to CAK cells induced greater cytotoxicity than either treatment alone. Inclusion of soluble MICB significantly reduced cytotoxicity.
  
  
  CONCLUSIONS
  Gemcitabine induced MICA/B expression in HepG2 cells, resulting in synergistic enhancement of the cytotoxic effects of NKG2D-high CAK cells. The combination of gemcitabine and CAK cells may have clinical therapeutic significance for HCC.
authors.affiliation: Fukuoka General Cancer Clinic, 3-1-1 Sumiyoshi, Hakata-ku, Fukuoka 812-0018, Japan. tmorisaki@cancer-clinic.jp
authors.forename: Takashi
authors.initials: T
authors.lastname: Morisaki
authors.forename: Hideya
authors.initials: H
authors.lastname: Onishi
authors.forename: Norihiro
authors.initials: N
authors.lastname: Koya
authors.forename: Akifumi
authors.initials: A
authors.lastname: Kiyota
authors.forename: Hiroto
authors.initials: H
authors.lastname: Tanaka
authors.forename: Masayo
authors.initials: M
authors.lastname: Umebayashi
authors.forename: Toshitatsu
authors.initials: T
authors.lastname: Ogino
authors.forename: Iori
authors.initials: I
authors.lastname: Nagamatsu
authors.forename: Mitsuo
authors.initials: M
authors.lastname: Katano
mesh_terms: D000964:Antimetabolites, Antineoplastic / Q000494:pharmacology*; D006528:Carcinoma, Hepatocellular / Q000097:blood / Q000473:pathology* / Q000628:therapy; D045744:Cell Line, Tumor / Q000187:drug effects / Q000276:immunology; D002478:Cells, Cultured / Q000187:drug effects; D003131:Combined Modality Therapy; D003602:Cytotoxicity, Immunologic; D003841:Deoxycytidine / Q000031:analogs & derivatives* / Q000494:pharmacology; D005434:Flow Cytometry; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D015395:Histocompatibility Antigens Class I / Q000096:biosynthesis* / Q000235:genetics; D006801:Humans; D066298:In Vitro Techniques; D007376:Interleukin-2 / Q000494:pharmacology; D008113:Liver Neoplasms / Q000097:blood / Q000473:pathology* / Q000628:therapy; D016260:Monocytes, Activated Killer / Q000276:immunology*; D016853:Muromonab-CD3 / Q000494:pharmacology; D055655:NK Cell Lectin-Like Receptor Subfamily K / Q000276:immunology*; D011994:Recombinant Proteins / Q000494:pharmacology; D000093542:Gemcitabine
chemical_list: D000964:Antimetabolites, Antineoplastic; D015395:Histocompatibility Antigens Class I; D007376:Interleukin-2; C527085:KLRK1 protein, human; C099187:MHC class I-related chain A; C098080:MICB antigen; D016853:Muromonab-CD3; D055655:NK Cell Lectin-Like Receptor Subfamily K; D011994:Recombinant Proteins; D003841:Deoxycytidine; D000093542:Gemcitabine