Characterization of a mutant E-cadherin protein encoded by a mutant gene frequently seen in diffuse-type human gastric carcinoma

Citation
Y. Fukudome et al., Characterization of a mutant E-cadherin protein encoded by a mutant gene frequently seen in diffuse-type human gastric carcinoma, INT J CANC, 88(4), 2000, pp. 579-583
Citations number
34
Categorie Soggetti
Onconogenesis & Cancer Research
Journal title
INTERNATIONAL JOURNAL OF CANCER
ISSN journal
00207136 → ACNP
Volume
88
Issue
4
Year of publication
2000
Pages
579 - 583
Database
ISI
SICI code
0020-7136(20001115)88:4<579:COAMEP>2.0.ZU;2-H
Abstract
The cell-cell adhesion molecule E-cadherin plays an essential role in the m aintenance and function of epithelial tissues. Altered expression of E-cadh erin has been implicated in tumor invasion. Analysis of mutations of the hu man E-cadherin gene in gastric carcinoma of the diffuse type has revealed t hat deletion of exon 8 or 9 in its cDNA appears to be predominant. In this study, we carried out structural and functional analyses of a mutant form o f E-cadherin in a cell line, HSC45-M2, established from a human signet ring -cell carcinoma, Although immunohistochemical analysis showed that the muta nt cadherin was localized at cell-cell contact sites as usually seen with t he wild type, these cells did not form compact colonies. HSC45-M2 cells exp ressed aberrant E-cadherin with an m.w. larger than that of the wild type. In these cells, we found deletion of the exon 9-intron 9 boundary including the splicing donor site in E-cadherin genomic DNA, RT-PCR indicated 2 tran scripts, which appeared to be caused by the splicing defect. Northern blott ing, however, showed that the transcript lacking exon 9 was predominantly d etected in these cells. The electrophoretic mobilities on SDS-PACE of the m utant E-cadherin protein in HSC45-M2 cells and the protein expressed from c DNA lacking exon 9 appeared identical. Analysis of the amino-terminal regio n of the mutant E-cadherin protein revealed that the cadherin was capable o f becoming a mature form by removal of its amino-terminal peptide. However, the mutant E-cadherin was susceptible to trypsinization in the presence of Ca2+ which is not the case for wild-type E-cadherin, suggesting that the m utant E-cadherin frequently found in diffuse-type gastric carcinoma may hav e lost its Ca2+-binding ability, leading to disruption of the tight cell-ce ll association. (C) 2000 Wiley-Liss, Inc.