Structure and function of the N-cadherin/catenin complex in retinoblastoma.
OBJECTIVE
To identify in human retinoblastoma and normal retinal tissue the type of cadherin, its relationship with cytoplasmic catenins, and its participation in invasion.


METHODS
The cadherin/catenin complex was characterized in surgical retinoblastoma specimens from five patients and human retinas from four donor eyes by immunocytochemistry, flow cytometry, and coimmunoprecipitation with antibodies against N-cadherin, alpha-catenin, and beta-catenin, followed by Western blot analysis or autoradiography. Y79 and WERI-Rb-1 retinoblastoma cell lines serve the evaluation of the cadherin/catenin complex in aggregation and collagen type I invasion in vitro. The association of the cadherin/catenin complex with the cytoskeleton was examined by an antibody-capping assay.


RESULTS
In retinoblastoma and normal retina N-cadherin associated with alpha-catenin and beta-catenin but not E- or P-cadherin. The N-cadherin/catenin complex formed a regular, linear, and continuous honeycomb pattern in normal retina that was irregular, clustered, and interrupted in retinoblastoma. The N-cadherin/catenin complex was found also in the retinoblastoma cell lines WERI-Rb and Y79, in which it also showed an irregular pattern. Both cell lines were invasive in collagen type I, and invasion was inhibited by the GC-4 antibody, which functionally neutralizes N-cadherin. Less GC-4 antibody was needed to inhibit invasion of Y79 cells, which expressed N-cadherin at a lower level, than to inhibit invasion of WERI-Rb-1 cells. In both cell lines, antibody capping of the N-cadherin/catenin complex indicated that its linkage with the cytoskeleton were weak or absent.


CONCLUSIONS
Retinoblastoma cells, in contrast with normal retina, express an N-cadherin/catenin complex that is irregularly distributed and weakly linked to the cytoskeleton. In retinoblastoma, this complex acts as an invasion promoter.
Van Aken
Elisabeth H
EH
Department of Ophthalmology, Laboratory of Experimental Cancerology, Ghent University Hospital, De Pintelaan 185, B-9000 Gent, Belgium.
Papeleu
Peggy
P
De Potter
Patrick
P
Bruyneel
Erik
E
Philippé
Jan
J
Seregard
Stefan
S
Kvanta
Anders
A
De Laey
Jean-Jacques
JJ
Mareel
Marc M
MM
D001345:Autoradiography; D015153:Blotting, Western; D015820:Cadherins / Q000378:metabolism*; D003598:Cytoskeletal Proteins / Q000378:metabolism*; D005434:Flow Cytometry; D019084:Fluorescent Antibody Technique, Indirect; D006801:Humans; D007124:Immunoenzyme Techniques; D011233:Precipitin Tests; D012160:Retina / Q000378:metabolism; D019572:Retinal Neoplasms / Q000378:metabolism* / Q000473:pathology; D012175:Retinoblastoma / Q000378:metabolism* / Q000473:pathology; D015534:Trans-Activators; D014407:Tumor Cells, Cultured / Q000378:metabolism; D051178:alpha Catenin; D051176:beta Catenin
C495273:CTNNA1 protein, human; C495270:CTNNB1 protein, human; D015820:Cadherins; D003598:Cytoskeletal Proteins; D015534:Trans-Activators; D051178:alpha Catenin; D051176:beta Catenin