Expression of claudin-1, -3, -4, -5 and -7 proteins in low grade colorectal carcinoma of canines
Cs. Jakab1, M. Rusvai1, P. Gálfi3, Z. Szabó4, Á. Szabára1 and J. Kulka2
1Szent István University, Faculty of Veterinary Science, Department of Pathology and Forensic Veterinary Medicine, Budapest, Hungary, 22nd Department of Pathology, Semmelweis University, Budapest, Hungary and 3Szent István University, Faculty of Veterinary Science, Department of Pharmacology and Toxicology Budapest, Hungary and 4Szent István University, Faculty of Veterinary Science, Department and Clinic of Internal Medicine.
Offprint requests to: Csaba Jakab, Szent István University, Faculty of Veterinary Medicine, Department of Pathology and Forensic Veterinary Medicine, 1078 István utca 2., Budapest, Hungary. e-mail: Jakab.Csaba@aotk.szie.hu
Summary. The aim of the present study was to characterise the expression pattern of claudin-1, -3, -4, -5 and -7 tight junction proteins in canine normal colorectum and in the low-grade, tubulopapillary colorectal carcinoma in canines. Methods and results: The biopsy samples included 10 canine normal colorectal tissues and 20 canine low grade colorectal carcinomas (CLGCCs). The canine normal colorectal mucosa was negative for claudin-1. Claudin-1 was detected as a non-diffuse intense membrane labelling of neoplastic epithelial cells in low grade colorectal cancer in canines. Fifty five per cent of all tumours showed a weak cytoplasmic pattern of staining for claudin-1 protein. The normal colorectal mucosa showed diffuse punctate positivity for claudin-3. Claudin-3 was detected as an intense lateral membrane labelling of tumour cells in CLGCCs. Claudin-4 expression in surface and crypt epithelial cells of the intact colorectal mucosa in canines was punctate. Claudin-4 molecule was detected as a lateral membrane labelling of neoplastic cells in CLGCCs. The epithelium of the CLGCCs and the low grade colorectal carcinoma were negative for claudin-5. The surface and crypt epithlial cells of the canine normal colorectal mucosa showed a diffuse lateral membranous pattern of staining for claudin-7. Claudin-7 molecule was detected as an intense membrane labelling of neoplastic cells in CLGCCs. Seventy per cent of all tumours showed weak cytoplasmic positivity for claudin-7. Conclusion: Consequently, we hypothesize that claudin-1 plays a role in the progression of CLGCCs. Further functional studies are needed to clarify the biological role of the mislocalization of the claudin-1 molecule from cell membrane to the cytoplasm in CLGCCs. Lower claudin-4 expression suggests that reduced expression of claudin-4 molecule may lead to cellular disorientation, detachment and invasion of CLGCCs. Further functional studies are needed to clarify the biological role of overexpression and mislocalisation of claudin-7 in CLGCCs. Histol Histopathol 25, 55-62 (2010)
Key words: Canine low grade colorectal carcinoma, Immunohistochemistry, Claudin-1, -3, -4, -5, -7