Immunohistochemical expression profile of β-catenin, E-cadherin, P-cadherin, laminin-5γ2 chain, and SMAD4 in colorectal serrated adenocarcinoma.

The immunohistochemical expression of cell adhesion molecules in colorectal serrated adenocarcinoma is still unknown. The immunostaining patterns of β-catenin, E-cadherin, P-cadherin, laminin 5γ2, and SMAD4 and their relationship to survival were studied in different tumor areas, namely, tumor center and invasive front, the latter comprising tumor bud and non-tumor bud clusters, as described in a previous study of 66 serrated adenocarcinomas and matched conventional carcinomas. Compared with conventional carcinomas, serrated adenocarcinomas showed significantly reduced nuclear β-catenin, membranous E-cadherin, and nuclear SMAD4 but an increased cytoplasmic expression of laminin-5γ2 at the invasive front that was particularly pronounced in the tumor buds. E-cadherin loss at the invasive front was identified as an independent prognostic factor for a poorer outcome in serrated adenocarcinoma. Serrated adenocarcinoma shows a distinct immunohistochemical profile at the invasive front compared with conventional carcinoma, which may account for its less favorable outcome. The lower frequency of nuclear β-catenin in SAC, especially in right-sided tumors, suggests that molecular mechanisms other than the canonical Wnt/β-catenin pathway may have a role in tumor bud formation.