VARYING EXPRESSION OF CYTOKERATIN AND NEUROFILAMENTS IN NEURO-ENDOCRINE TUMORS OF HUMAN GASTROINTESTINAL-TRACT

  • 1 January 1985
    • journal article
    • research article
    • Vol. 52  (4) , 429-436
Abstract
Cases (12) of gastrointestinal neuroendocrine tumors, including 8 carcinoids and 4 pancreatic islet cell tumors or their metastases, were immunohistochemically analyzed for the expression of different types of intermediate filament proteins. All of the tumors showed cytokeratin positivity in immunostaining, and the Western blotting technique revealed 45- and 52-kilodalton [kDa] cytokeratins in carcinoid tumors. Three of the islet cell tumors, but none of the carcinoid tumors, showed, in addition, varying numbers of neurofilament-positive tumor cells when evaluated with rabbit and mouse monoclonal antineurofilament antibodies. The presence of only the 70-kDa neurofilament and cytokeratin polypeptides in an islet cell tumor was revealed also by using the Western blotting technique. On the other hand, both fetal and adult pancreatic islet cells showed only cytokeratin positivity. Neurofilament-positive epithelial cells were not found in normal small intestines either. The results show epithelial characteristics in normal gastrointestinal neuroendocrine cells and neuroendocrine tumors by their expression of cytokeratin. In addition, some islet cell tumors display the 70-kDa neurofilament protein which suggests the acquisition of a new type of intermediate filament during the neoplastic change.