title: Expression of co-stimulator 4-1BB molecule in hepatocellular carcinoma and adjacent non-tumor liver tissue, and its possible role in tumor immunity.
abstract: OBJECTIVE
  To investigate the expression of 4-1BB molecule in hepatocellular carcinoma (HCC) and its adjacent tissues.
  
  
  METHODS
  Reverse transcription-polymerase chain reaction (RT-PCR) was used to determine the gene expression of 4-1BB in hepatocarcinoma and its adjacent tissues, and peripheral blood mononuclear cells (PBMCs) from both HCC and health control groups. Flow cytometry was used to analyse the phenotypes of T cell subsets from the blood of HCC patients and healthy volunteers, and further to determine whether 4-1BB molecules were also expressed on the surface of CD4+ and CD8+ T cells. The localization of 4-1BB proteins on tumor infiltrating T cells was determined by direct immunofluorescence cytochemical staining and detected by confocal microscopy.
  
  
  RESULTS
  4-1BB mRNA, which was not detectable in normal liver, was found in 19 liver tissues adjacent to tumor edge (<1.0 cm). Low expression of 4-1BB mRNA was shown in 8 tumor tissues and 6 liver tissues located within 1 to 5 cm away from tumor edge. In PBMCs, 4-1BB mRNA was almost not detected. Percentage of CD4+, CD8+ and CD3+/CD25+ T cells, as well as ratio of CD4 to CD8 revealed no difference between groups (P>0.05, respectively), while a significant lower percentage of CD3+ T cell was found in HCC group as compared to healthy control group (P<0.05). However, 4-1BB molecules were almost not found on the surface of CD4+ and CD8+ T cells in HCC and healthy control group. Double-staining of 4-1BB+/CD4+ and 4-1BB+/CD8+ immunofluorescence on tumor infiltrating T cells was detected in 13 liver tissues adjacent to tumor edge (<1.0 cm) by confocal microscopy.
  
  
  CONCLUSIONS
  Although HCC may escape from immune attack by weak immunogenicity or downregulated expression of MHC-1 molecules on the tumor cell surface, tumor infiltrating T cells can be activated via other costimulatory signal pathways to exert a limited antitumor effect on local microenvironment. The present study also implicates that modulating 4-1BB/4-1BBL costimulatory pathway may be an effective immunotherapy strategy to augment the host response.
authors.affiliation: Department of Hepatobiliary and Pancreatic Surgery, First Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou 310000, Zhejiang Province, China. wanyl036@sina.com
authors.forename: Yun-Le
authors.initials: YL
authors.lastname: Wan
authors.forename: Shu-Sen
authors.initials: SS
authors.lastname: Zheng
authors.forename: Zhi-Cheng
authors.initials: ZC
authors.lastname: Zhao
authors.forename: Min-Wei
authors.initials: MW
authors.lastname: Li
authors.forename: Chang-Ku
authors.initials: CK
authors.lastname: Jia
authors.forename: Hao
authors.initials: H
authors.lastname: Zhang
mesh_terms: D000328:Adult; D000368:Aged; D015703:Antigens, CD; D015496:CD4-Positive T-Lymphocytes / Q000502:physiology; D018414:CD8-Positive T-Lymphocytes / Q000502:physiology; D006528:Carcinoma, Hepatocellular / Q000276:immunology* / Q000503:physiopathology; D005260:Female; D015972:Gene Expression Regulation, Neoplastic / Q000276:immunology; D006801:Humans; D008113:Liver Neoplasms / Q000276:immunology* / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D010641:Phenotype; D012333:RNA, Messenger / Q000032:analysis; D017475:Receptors, Nerve Growth Factor / Q000235:genetics* / Q000276:immunology*; D018124:Receptors, Tumor Necrosis Factor / Q000235:genetics* / Q000276:immunology*; D053261:Tumor Necrosis Factor Receptor Superfamily, Member 9
chemical_list: D015703:Antigens, CD; D012333:RNA, Messenger; D017475:Receptors, Nerve Growth Factor; D018124:Receptors, Tumor Necrosis Factor; C505714:TNFRSF9 protein, human; D053261:Tumor Necrosis Factor Receptor Superfamily, Member 9