title: Inverse correlation of HER2 with MHC class I expression on oesophageal squamous cell carcinoma.
abstract: BACKGROUND
  As HER2 is expressed in 30% of oesophageal squamous cell carcinomas (ESCCs), T-cell-based immunotherapy and monoclonal antibodies targeted against HER2 are attractive, novel approaches for ESCCs. However, it was shown that there is an inverse correlation between HER2 and MHC class I expression on tumours. Thus, the correlation between HER2 and MHC class I expressions on ESCC was evaluated.
  
  
  METHODS
  Expressions of MHC class I and HER2 in ESCC tissues (n=80) and cell lines were assessed by immunohistochemistry, fluorescence in situ hybridisation (FISH), and flow cytometry. We investigated whether HER2 downregulation with small interfering RNA (siRNA) in ESCC cell lines could upregulate the expression of MHC class I and the antigen presentation machinery components, and could increase their sensitivity for tumour antigen-specific CTLs.
  
  
  RESULTS
  There was an inverse correlation between HER2 and MHC class I expressions in both tumour tissues and cell lines. Downregulation of HER2 with siRNA resulted in the upregulation of MHC class I expression, leading to increased CTL recognition by tumour antigen-specific CTLs.
  
  
  CONCLUSIONS
  HER2-overexpressing ESCC tumour cells showed a reduced sensitivity for CTLs through the downregulation of MHC class I.
authors.affiliation: First Department of Surgery, University of Yamanashi, 1110 Shimokato, Chuo-city, Yamanashi 409-3898, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Maruyama
authors.forename: K
authors.initials: K
authors.lastname: Mimura
authors.forename: E
authors.initials: E
authors.lastname: Sato
authors.forename: M
authors.initials: M
authors.lastname: Watanabe
authors.forename: Y
authors.initials: Y
authors.lastname: Mizukami
authors.forename: Y
authors.initials: Y
authors.lastname: Kawaguchi
authors.forename: T
authors.initials: T
authors.lastname: Ando
authors.forename: H
authors.initials: H
authors.lastname: Kinouchi
authors.forename: H
authors.initials: H
authors.lastname: Fujii
authors.forename: K
authors.initials: K
authors.lastname: Kono
mesh_terms: D002294:Carcinoma, Squamous Cell / Q000235:genetics* / Q000378:metabolism; D045744:Cell Line, Tumor; D004938:Esophageal Neoplasms / Q000235:genetics* / Q000378:metabolism; D015870:Gene Expression; D005805:Genes, MHC Class I / Q000235:genetics*; D006801:Humans; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000096:biosynthesis / Q000235:genetics*
chemical_list: D018719:Erb-b2 Receptor Tyrosine Kinases