title: Loss of tight junction proteins (Claudin 1, 4, and 7) correlates with aggressive behavior in colorectal carcinoma.
abstract: BACKGROUND
  Tight junction proteins in the cell organize paracellular permeability and they play a critical role in apical cell-to-cell adhesion and epithelial polarity. Claudins are major integral membrane proteins of tight junctions, especially Claudin 1, 4, and 7, which are known as the impermeability Claudins. In this study, we investigated the importance of loss of Claudin 1, 4, and 7 expression, and their relation to tumor progression in colorectal cancer patients.
  
  
  METHODS
  Loss of Claudin 1, 4, and 7 expression was examined by immunohistochemical method in 70 patients diagnosed with colorectal cancer. Cases with loss of Claudin expression in <1/3 of tumor cells were classified as mild loss, whereas cases with loss of Claudin expression ³1/3 of tumor cells were classified as moderate-to-marked loss in order to evaluate the relation between loss of Claudin 1, 4, and 7 expression and clinicopathologic data.
  
  
  RESULTS
  The severe suppression of Claudin 1, 4, and 7 expression was found to be significantly related to the depth of tumor invasion, positive regional lymph nodes, histological grade, lymphovascular invasion, perineural invasion, and lymphocytic response. Additionally, severity of loss in Claudin 4 expression was found to have a relation with distant metastasis.
  
  
  CONCLUSIONS
  Claudin 1, 4, and 7 are important building blocks of paracellular adhesion molecules. Their decreased expression in colorectal cancer seems to have critical effects on cell proliferation, motility, invasion, and immune response against the tumor.
authors.affiliation: Department of Pathology, Antalya Education and Research Hospital, Antalya, Turkey.
authors.forename: Dinç
authors.initials: D
authors.lastname: Süren
authors.affiliation: Department of Medical Oncology, Ministry of Health Batman Regional Government Hospital, Batman, Turkey.
authors.forename: Mustafa
authors.initials: M
authors.lastname: Yıldırım
authors.affiliation: Department of Radiation Oncology, Süleyman Demirel University, Isparta, Turkey.
authors.forename: Vildan
authors.initials: V
authors.lastname: Kaya
authors.affiliation: Department of Pathology, Antalya Education and Research Hospital, Antalya, Turkey.
authors.forename: Arsenal Sezgin
authors.initials: AS
authors.lastname: Alikanoğlu
authors.affiliation: Department of General Surgery, Antalya Education and Research Hospital, Antalya, Turkey.
authors.forename: Nurullah
authors.initials: N
authors.lastname: Bülbüller
authors.affiliation: Department of Medical Oncology, Antalya Education and Research Hospital, Antalya, Turkey.
authors.forename: Mustafa
authors.initials: M
authors.lastname: Yıldız
authors.affiliation: Department of Pathology, Antalya Education and Research Hospital, Antalya, Turkey.
authors.forename: Cem
authors.initials: C
authors.lastname: Sezer
mesh_terms: D002463:Cell Membrane Permeability / Q000502:physiology*; D002465:Cell Movement / Q000502:physiology; D049109:Cell Proliferation / Q000502:physiology; D062445:Claudin-1 / Q000172:deficiency; D062506:Claudin-4 / Q000172:deficiency; D057167:Claudins / Q000172:deficiency; D015179:Colorectal Neoplasms / Q000378:metabolism / Q000503:physiopathology*; D006801:Humans; D007150:Immunohistochemistry; D009361:Neoplasm Invasiveness / Q000503:physiopathology*; D009362:Neoplasm Metastasis / Q000503:physiopathology*; D062725:Tight Junction Proteins / Q000172:deficiency*
chemical_list: C568108:CLDN1 protein, human; C568157:CLDN4 protein, human; C473255:CLDN7 protein, human; D062445:Claudin-1; D062506:Claudin-4; D057167:Claudins; D062725:Tight Junction Proteins