ABSTRACT
Beta-catenin is an ubiquitously expressed cytoplasmic protein that has a crucial role in both E-cadherin-mediated cell-cell adhesion and as a downstream signaling molecule in the wingless pathway. Stabilization of beta-catenin followed by nuclear translocation and subsequent T-cell factor/lymphoid-enhancing factor-mediated transcriptional activation has been proposed as an important step in oncogenesis. Stabilization may occur through activating mutations in exon-3 at the phosphorylation sites for ubiquitination and degradation of beta-catenin. Immunohistochemical subcellular localization of beta-catenin and mutational analysis of exon-3 of the beta-catenin gene by single-strand conformational polymorphism followed by DNA sequencing was performed on 37 samples from 31 patients with anaplastic thyroid carcinoma. Immunofluorescent staining showed nuclear localization in 15 (42%) of the 36 samples examined. Nucleotide sequencing of mobility shifts detected by single-strand conformational polymorphism revealed somatic alterations in 19 (61%) of the 31 patients analyzed. We conclude that mutations in beta-catenin are common in anaplastic thyroid cancer and that they may activate transcription, as illustrated by frequent nuclear localization of the protein. These findings support the idea that beta-catenin acts as an oncogene and contributes to the highly aggressive behavior of this tumor.
Subject(s)
Carcinoma/genetics , Cytoskeletal Proteins/genetics , Thyroid Neoplasms/genetics , Trans-Activators , Amino Acid Sequence , Calcium-Calmodulin-Dependent Protein Kinases/genetics , Calcium-Calmodulin-Dependent Protein Kinases/metabolism , Carcinoma/metabolism , Carcinoma/pathology , Cell Nucleus/metabolism , Cytoskeletal Proteins/metabolism , Exons/genetics , Fluorescent Antibody Technique , Glycogen Synthase Kinase 3 , Humans , Molecular Sequence Data , Mutation , Phosphorylation , Thyroid Neoplasms/metabolism , Thyroid Neoplasms/pathology , beta CateninABSTRACT
Enzyme-linked immunosorbent assays (ELISA) have enabled earlier identification of Mycobacterium tuberculosis (TB) in clinical settings by utilizing both TB antibody and antigen detection. We studied the sensitivity and specificity of ELISA detection of TB antigen by using a commercially available anti-BCG antibody in conjunction with BACTEC 7H12B culture bottles. We compared these results against those obtained with cultures of Mycobacterium avium-intracellulare and Mycobacterium kansasii. All BACTEC bottles were inoculated with known concentrations of organisms. TB antigen was detected by ELISA in BACTEC culture bottles of TB 12 days before the BACTEC system could itself identify the species. A growth index of greater than or equal to 10 reliably indicated that tuberculosis antigen was detectable by ELISA. The correlation between growth index and antigen concentration was extremely high (r = 0.95 and p less than 0.001). There was insignificant cross-reactivity with the other atypical mycobacteria at the levels of growth tested. This technique potentially offers a sensitive and specific means for the early identification of TB in BACTEC culture bottles.
