Immunolocalisation of β catenin in intestinal polyps of Peutz-Jeghers and juvenile polyposis syndromes

Abstract

Aim-To examine the membranous and nuclear distribution of β catenin in the epithelial cells of gut polyps from Peutz-Jeghers syndrome and juvenile polyposis in comparison with other types of polyps and tumours. Methods- Immunohistochemistry for β catenin and proliferation markers was performed on conventional paraffin sections. Immunohistological staining was carried out on Peutz-Jeghers syndrome polyps from four different families, on juvenile polyposis polyps from two different families, on solitary juvenile polyps, and on hyperplastic polyps. The immunohistochemistry was evaluated qualitatively in relation to defined areas of the polyps. Results-All polyps from the hamartomatous polyposis syndromes (Peutz-Jeghers syndrome and juvenile polyposis) showed nuclear localisation of β catenin in some epithelial cell nuclei. In Peutz-Jeghers syndrome polyps β catenin positive nuclei were seen at the base of the deep crypt infoldings. In juvenile polyposis polyps and in some solitary juvenile polyps they were found in irregularly distributed cryptal epithelial cells corresponding to the proliferative compartments. Normal mucosa of the gut and hyperplastic polyps of the colon do not show nuclear staining for β catenin. Conclusions-The dysregulation of cellular β catenin distribution is not only a phenomenon of adenoma formation and adenoma progression in the colon-it is at least locally present in polyps of the hamartomatous type and is related to the proliferation zones of these polyps. The nuclear translocation of β catenin most probably reflects a disturbed β catenin metabolism. In view of the different functions of β catenin during development and cell differentiation, the nuclear translocation of β catenin is likely to be an important factor in enhanced cell proliferation which escapes local control mechanisms.