title: Nuclear beta-catenin in colorectal tumors: to freeze or not to freeze? Colon Cancer Team at IMAS.
abstract: beta-Catenin mediates the interaction of E-cadherin with alpha-catenin and the actin cytoskeleton. Recent evidence indicates that when the tumor suppressor gene APC is inactivated, beta-catenin can translocate to the nucleus, where it acts as a transcriptional regulator. Because APC is inactivated in most colorectal cancers, beta-catenin nuclear localization would be expected in these tumors. In a study of adhesion molecule expression in frozen colorectal cancer tissues, we were surprised by failure to detect nuclear beta-catenin. Here we compared the reactivity of an anti-beta-catenin monoclonal antibody with 11 colorectal cancers using immunohistochemistry on sections of frozen or paraffin-embedded samples. beta-Catenin was never detected in the nuclei of normal or tumor cells in frozen tissue sections. By contrast, in 8/11 cases it was detected in the nuclei of tumor cells but not of normal cells in paraffin-embedded tissue sections. These results were confirmed with an independent rabbit polyclonal anti-beta-catenin serum. We also examined beta-catenin distribution in SW480 colon cancer cells, in which its nuclear accumulation has been reported. As in tissues, nuclear beta-catenin was detected in paraffin-embedded but not in frozen samples. These findings are relevant because of the increasing interest in the study of beta-catenin in tumors, based on its dual role in cell adhesion and transcriptional regulation.
authors.affiliation: Unit of Cellular and Molecular Biology, Municipal Institute of Medical Investigation, Barcelona, Spain.
authors.forename: A
authors.initials: A
authors.lastname: Munné
authors.forename: M
authors.initials: M
authors.lastname: Fabre
authors.forename: M L
authors.initials: ML
authors.lastname: Mariñoso
authors.forename: M
authors.initials: M
authors.lastname: Gallén
authors.forename: F X
authors.initials: FX
authors.lastname: Real
mesh_terms: D002467:Cell Nucleus / Q000378:metabolism*; D003106:Colon / Q000378:metabolism / Q000648:ultrastructure; D015179:Colorectal Neoplasms / Q000378:metabolism* / Q000648:ultrastructure; D003598:Cytoskeletal Proteins / Q000378:metabolism*; D005629:Frozen Sections; D019073:HT29 Cells; D006801:Humans; D007413:Intestinal Mucosa / Q000378:metabolism / Q000648:ultrastructure; D016612:Paraffin Embedding; D015534:Trans-Activators; D014407:Tumor Cells, Cultured; D051176:beta Catenin
chemical_list: C495270:CTNNB1 protein, human; D003598:Cytoskeletal Proteins; D015534:Trans-Activators; D051176:beta Catenin