A major function of the cell-to-cell adhesion molecule Ecadherin is the maintenance of cell adhesion and tissue integrity. E-cadherin de®ciency in tumours leads to changes in cell morphology and motility, so that Ecadherin is considered to be a suppressor of invasion. In this study we investigated the functional consequences of three tumour-associated gene mutations that aect the extracellular portion of E-cadherin: in-frame deletions of exons 8 or 9 and a point mutation in exon 8, as they were found in human gastric carcinomas. Human MDA-MB-435S breast carcinoma cells and mouse L ®broblasts were stably transfected with the wild-type and mutant cDNAs, and the resulting changes in localization of E-cadherin, cell morphology, strength of calcium-dependent aggregation as well as cell motility and actin cytoskeleton organization were studied. We found that cells transfected with wild-type E-cadherin showed an epitheloid morphology, while all cell lines expressing mutant E-cadherin exhibited more irregular cell shapes. Cells expressing Ecadherin mutated in exon 8 showed the most scattered appearance, whereas cells with deletion of exon 9 had an intermediate state. Mutant E-cadherins were localized to the lateral regions of cell-to-cell contact sites. Additionally, both exon 8-mutated E-cadherins showed apical and perinuclear localization, and actin ®laments were drastically reduced. MDA-MB-435S cells with initial calciumdependent cell aggregation exhibited decreased aggregation and, remarkably, increased cell motility, when mutant E-cadherin was expressed. Therefore, we conclude that these E-cadherin mutations may not simply aect cell adhesion but may act in a trans-dominant-active manner, i.e. lead to increased cell motility. Our study suggests that E-cadherin mutations aecting exons 8 or 9 are the cause of multiple morphological and functional disorders and could induce the scattered morphology and the invasive behaviour of diuse type-gastric carcinomas.

In-frame deletions from the E-cadherin mRNA, coding for a homophilic cell adhesion molecule, are characteristic for diffuse-type gastric carcinomas. Using immunohistochemical analysis the mutant form cannot be distinguished from normal E-cadherin, making results difficult to interpret. In this study, a rat monoclonal antibody , designated E-cad delta 9 -1, was generated against a peptide spanning the fusion junction region between exons 8 and 10. This new epitope is present in an E-cadherin variant that lacks exon 9 from the mRNA due to different splice-site gene mutations. Using Western blotting and immunohistochemistry of E-cadherin-transfected cells, we demonstrate that E-cad delta 9 -1 specifically reacts with E-cadherin lacking exon 9 but not with the wildtype protein. No immunoreactivity was observed in 31 nontumorous and embryonal tissues analyzed. In gastric carcinoma specimens known to express mutant E-cadherin mRNA lacking exon 9 , E-cad delta 9 -1 targets exclusively tumor cells in routine formalinfixed and paraffin-embedded material from biopsies, primary tumors , and lymph node metastases. In a retrospective series of 172 diffuse-type gastric carcinomas expressing E-cadherin , E-cad delta 9 -1 reacted with 22 tumors (13%). This new tumor marker- The calcium-dependent homophilic cell adhesion molecule E-cadherin and associated catenins, cytoplasmic plaque proteins, link polarized epithelial cells and maintain the structural integrity of an epithelial monolayer. Moreover, the cadherin/catenin multiprotein complex is implicated in developmental processes and cell signaling.

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Struvite, MgNH(4)PO(4).6H(2)O, rather than apatite or amorphous calcium phosphate is precipitated when phosphate is added to seawater containing more than 0.01M NH(4)(+) ions. Struvite may have precipitated from evaporating seawater on the primitive earth, and may have been important for prebiotic phosphorylation.

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