INTERMEDIATE FILAMENTS AS DIFFERENTIATION MARKERS OF EXOCRINE PANCREAS .2. EXPRESSION OF CYTOKERATINS OF COMPLEX AND STRATIFIED EPITHELIA IN NORMAL PANCREAS AND IN PANCREAS CANCER

Cytokeratin (CK) expression in tumors generally reflects the CK patter n of the corresponding normal epithelium. Pancreas cancers express CK of simple epithelia 7, 8, 18 and 19, as normal ductal cells. To analyz e whether CK of complex or stratified epithelia are abnormally express ed in pancreas cancers, we have used polypeptide-specific mouse monocl onal antibodies (MAbs) detecting CK 5, CK 10, CK 13, CK 14 and CK 17, and an antibody detecting CK 13, CK 1 5 and CK 16. The streptavidin-pe roxidase technique was applied on sections of fresh-frozen specimens o f normal pancreas and of pancreas cancer. None of these polypeptides w ere expressed by normal acinar and centro-acinar cells. CK 5, CK 14 an d CK 17 were expressed by less than 5% of cells in normal ducts, where as CK 10, CK 13, CK 15 and CK 16 were not expressed at all. In tumors, CK 14, CK 15/16 and CK 17 were detected in the majority of cases stud ied; CK 5, CK 10 and CK 13 were present in a sub-population of pancrea s cancers. CK of complex/stratified epithelia were detected in areas o f glandular differentiation, but expression was more intense in areas of squamous differentiation. In pancreatitis adjacent to cancer, CK of complex/stratified epithelia were weakly detected or undetectable. Th ese results suggest that up-regulation of these CK takes place in panc reas cancer. The CK phenotype may be of help in the differential diagn osis of this tumor. (C) 1993 Wiley-Liss, Inc.