DISTRIBUTION OF THE CADHERIN-CATENIN COMPLEX IN NORMAL HUMAN THYROID EPITHELIUM AND A THYROID-CARCINOMA CELL-LINE

E-cadherin is the major cell-cell adhesion molecule expressed by epith elial cells. Cadherins form a complex with three cytoplasmic proteins, alpha-, beta-, and gamma-catenin, and the interaction between them is crucial for anchoring the actin cytoskeleton to the intercellular adh erens junctions. The invasive behavior of cancer cells has been attrib uted to a dysfunction of these molecules, In this study, we examined t he distribution of the cadherin-catenin complex in a Chinese human thy roid cancer cell line, CGTH W-2, compared with that in normal human th yroid epithelial cells. In the normal cells, using immunofluorescence staining, E-cadherin and alpha-, beta-, and gamma-catenin were Found t o be localized at the intercellular junction and appeared as 135, 102, 90, and 80 kD proteins on Western blots. In CGTH W-2 cells, no E-cadh erin and gamma-catenin immunoreactivity was detected by immunofluoresc ence or Western blotting; alpha- and beta-catenin were detected as 102 and 90 kD proteins on blots brit gave a diffuse cytoplasmic immunoflu orescence staining pattern in most cells, while beta-catenin was also distributed throughout the cytoplasm in most cells but was found at th e cell junction in some, where it colocalized with alpha-actinin. The present data indicate that the loss of cell adhesiveness in these canc er cells may be due to incomplete assembly of the cadherin-catenin com plex at the cell junction. However, this defect did not affect the lin kage of actin bundles to vinculin-enriched intercellular junctions. J. Cell. Biochem. 70:330-337, 1998. (C)1998 Wiley-Liss, Inc.