title: Down-regulated claudin-7 immunoexpression in urothelial carcinoma of the urinary bladder.
abstract: OBJECTIVE
  To analyse the gene-expression level of claudin-7 in urothelial carcinoma (UC) of the urinary bladder, and its relationship with clinicopathological variables.
  
  
  METHODS
  This study included 68 specimens of UC of the bladder, comprising 35 with non-muscle-invasive (NMI), stage Ta-T1, and 33 with muscle-invasive (MI) tumours, T2-T4, and 26 of normal urothelium (NU). Total RNA was extracted and 1 μg was reverse transcribed using a cDNA kit. RT-PCR was conducted using SYBR Green I dye to examine the expression levels of the target gene (claudin-7) and the housekeeping gene glyceraldehyde-3-phosphate dehydrogenase. Using confocal-laser scanning light microscopy, immunohistochemistry (IHC) was used to validate the RT-PCR data. The correlation between claudin-7 and the clinicopathological variables was assessed.
  
  
  RESULTS
  Claudin-7 was down-regulated in UC samples compared to NU samples (P < 0.001). NMI (Ta-T1) tumours had significantly higher claudin-7 expression than MI (⩾pT2) tumours (P = 0.012). There was no significant difference between patients with G1-2 tumours and those with G3 tumours (P = 0.19). There was no significant difference between patients with recurrent NMI UC and those with no recurrence (P = 0.61). IHC showed a lower expression of claudin-7 in the UC samples than NU samples, and in MI UC than in NMI UC.
  
  
  CONCLUSIONS
  These results indicate that a reduced expression of claudin-7 correlates with the invasiveness and progression of UC of the urinary bladder. Further studies are needed to validate claudin-7 as a marker for UC.
authors.affiliation: Urology Department, Assiut University Hospitals, Assiut, Egypt.
authors.forename: Mohamed
authors.initials: M
authors.lastname: Gadelmoula
authors.affiliation: Department of Urology, Institute of Health Biosciences, The University of Tokushima Graduate School of Medicine, Tokushima, Japan.
authors.forename: Tomoharu
authors.initials: T
authors.lastname: Fukumori
authors.affiliation: Department of Urology, Institute of Health Biosciences, The University of Tokushima Graduate School of Medicine, Tokushima, Japan.
authors.forename: Hiroyoshi
authors.initials: H
authors.lastname: Nakatsuji
authors.affiliation: Urology Department, Assiut University Hospitals, Assiut, Egypt.
authors.forename: Mohammed
authors.initials: M
authors.lastname: Elgammal
authors.affiliation: Department of Anatomy, Kawasaki Medical School, Kurashiki, Okayama, Japan.
authors.forename: Kazunori
authors.initials: K
authors.lastname: Toida
authors.affiliation: Department of Urology, Institute of Health Biosciences, The University of Tokushima Graduate School of Medicine, Tokushima, Japan.
authors.forename: Hiro-Omi
authors.initials: HO
authors.lastname: Kanayama
keywords: (N)MI, (non-)muscle-invasive; Bladder cancer; Claudin-7; GAPDH, glyceraldehyde-3-phosphate dehydrogenase; NU, normal urothelium; Real-time PCR; Tight junction proteins; UC, urothelial carcinoma; Urothelial carcinoma