Tumour-associated E-cadherin mutations alter cellular morphology, decrease cellular adhesion and increase cellular motility.
A major function of the cell-to-cell adhesion molecule E-cadherin is the maintenance of cell adhesion and tissue integrity. E-cadherin deficiency in tumours leads to changes in cell morphology and motility, so that E-cadherin is considered to be a suppressor of invasion. In this study we investigated the functional consequences of three tumour-associated gene mutations that affect 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 fibroblasts 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 E-cadherin 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 filaments were drastically reduced. MDA-MB-435S cells with initial calcium-dependent 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 affect 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 affecting exons 8 or 9 are the cause of multiple morphological and functional disorders and could induce the scattered morphology and the invasive behaviour of diffuse type-gastric carcinomas.
Handschuh
G
G
GSF-Forschungszentrum für Umwelt and Gesundheit, Institut für Pathologie, Neuherberg, Germany.
Candidus
S
S
Luber
B
B
Reich
U
U
Schott
C
C
Oswald
S
S
Becke
H
H
Hutzler
P
P
Birchmeier
W
W
Höfler
H
H
Becker
K F
KF
D000199:Actins / Q000648:ultrastructure*; D000818:Animals; D015820:Cadherins / Q000235:genetics* / Q000378:metabolism; D002448:Cell Adhesion; D002465:Cell Movement; D005091:Exons; D005347:Fibroblasts / Q000166:cytology; D005455:Fluorescent Antibody Technique; D006801:Humans; D015674:Mammary Neoplasms, Animal / Q000235:genetics; D051379:Mice; D018613:Microscopy, Confocal; D008957:Models, Genetic; D009154:Mutation; D017354:Point Mutation; D013274:Stomach Neoplasms / Q000235:genetics* / Q000473:pathology; D014162:Transfection; D014407:Tumor Cells, Cultured; D014945:Wound Healing
D000199:Actins; D015820:Cadherins