Role of Necl-5 in the pathophysiology of colorectal lesions induced by dimethylhydrazine and/or dextran sodium sulphate.

Necl-5 is an immunoglobulin-like molecule that was originally identified as a poliovirus receptor. Although Necl-5 expression is often up-regulated in cancer cells, its pathophysiological significance in the development of cancer remains unclear. We investigated the roles of Necl-5 in the development of colitis-associated neoplasia. Necl-5-deficient mice were generated and treated with dimethylhydrazine (DMH) and/or dextran sodium sulphate (DSS) to induce colitis and its associated neoplasias. Colon tissues were examined for histology, Ki-67 expression by immunohistochemistry and K-ras gene mutation. Colon tumours occurred significantly less frequently in heterozygous (Necl-5+/−) or homozygous Necl-5-deficient (Necl-5−/−) mice than in wild-type (WT) mice with DMH/DSS treatment. Total ulcer index and inflammatory cell infiltration were significantly lower in Necl-5−/− mice than in WT mice with DSS alone or DMH/DSS treatment. Colon tumours in both WT and Necl-5−/− mice showed high cell proliferation ability but lacked K-ras mutation. The total Ki-67 labelling index in non-neoplastic colon epithelium was significantly higher in WT (45.9 ± 0.94) than in Necl-5+/− (34.3 ± 1.40) or Necl-5−/− (27.7 ± 1.15) mice with DMH/DSS treatment (p < 0.001). Necl-5 plays a role in the development of colitis-associated cancer by up-regulating colonic mucosal cell proliferation. Copyright © 2008 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.