Abstracts Poster Abstracts - Dr Falk

16Different expressions of claudins in endocrine and exocrinetumors of the pancreasBorka Katalin, Kiss András, Kaliszky Péter*, Kupcsulik Péter*, Schaff Zsuzsa2nd Department of Pathology and *1st Department of Surgery, Semmelweis University,Budapest, HungaryIntroduction: A new family of tight junction (TJ) proteins called claudins are responsiblefor cell adhesion, polarity and paracellular permeability. Although changes inpermeability of TJs were noted in several cancers, the role of claudins in carcinogenesisis controversial. Claudin 4 overexpression was reported in primary and metastaticpancreatic adenocarcinomas. These findings support use of claudin 4 as target for noveltherapeutics of pancreatic cancers.Aims: To analyse different claudin expressions in human pancreatic endocrine tumorsand ductal carcinomas using a panel of polyclonal (claudins 1, 3, 7) and monoclonal(claudins 2, 4) antibodies.Methods: Twenty formalin fixed, paraffin embedded pancreatic endocrine tumors andten pancreatic ductal carcinomas were studied, and immunohistochemical evaluationperformed to analyse claudin 1, 2, 3, 4 and 7 expressions. Semiquantitative evaluationwas used for the area of extension (0-5) and intensity (0-3) of reaction.Results: Claudins 1, 2 proved negative in all endocrine tumors. The majority (7/10) ofductal carcinomas was positive for claudin 4, while endocrine tumors were negative. Incontrast, claudin 7 showed high expression in all endocrine tumors, however, ductalcarcinomas did not express the protein. Claudin 3 was detected in 80% (16/20) ofendocrine tumors, while ductal carcinomas were negative. Claudin 7 expression wassignificantly higher in endocrine tumor cells, compared with claudin 3 (p < 0.0032).Conclusion: Our findings support that claudins 3 and 7 are specific marker forendocrine pancreatic tumors in contrast to ductal carcinomas. Further studies arenecessary to assess the biological role of these proteins in pancreatic carcinogenesis.Supported by grants NKFP-1A/0023/2002, NKFP-1A/002/2004, OTKA-T037838