Loss of Coxsackie and adenovirus receptor downregulates alpha-catenin expression.
BACKGROUND
The Coxsackie and adenovirus receptor (CAR) has been shown to inhibit cancer cell proliferation, migration, and invasion. The underlying mechanisms, however, are poorly understood.


METHODS
The differential gene expression in the human colon cancer cell line DLD1 on RNAi-mediated functional CAR knockdown was analysed using oligo-array technology. Expression of alpha-catenin was determined by quantitative RT-PCR and western blotting. Proliferation, migration, and invasion after CAR knockdown were assessed by in vitro assays, and cell morphology in a three-dimensional context was evaluated using matrigel.


RESULTS
Oligo-array technology identified alpha-catenin as the strongest downregulated gene after CAR knockdown. Western blotting and quantitative RT-PCR confirmed a reduced alpha-catenin expression after CAR knockdown in DLD1 cells and in the rat intestinal cell line IEC-6. Functionally, both cell lines showed a marked increase in proliferation, migration, and invasion on CAR knockdown. In matrigel, both cell lines formed amorphous cell clusters in contrast to well-organised three-dimensional structures of CAR-expressing vector controls. Ectopic 're'-expression of alpha-catenin in DLD1 and IEC-6 CAR knockdown cells reversed these functional and morphological effects.


CONCLUSIONS
These data suggest that an interaction of CAR and alpha-catenin mediates the impact of CAR on cell proliferation, migration, invasion, and morphology.
Division of Gastroenterology and Hepatology, Department of Internal Medicine, Charité Medical School, Campus Virchow, Augustenburgerplatz 1, Berlin 13353, Germany.
K
K
Stecker
A
A
Koschel
B
B
Wiedenmann
M
M
Anders
D045744:Cell Line, Tumor; D002465:Cell Movement; D049109:Cell Proliferation; D062727:Coxsackie and Adenovirus Receptor-Like Membrane Protein; D015536:Down-Regulation; D005786:Gene Expression Regulation; D006801:Humans; D047468:Immunoprecipitation; D009361:Neoplasm Invasiveness; D011991:Receptors, Virus / Q000032:analysis / Q000502:physiology*; D051178:alpha Catenin / Q000032:analysis / Q000235:genetics* / Q000502:physiology
C568771:CLMP protein, human; C568773:Clmp protein, rat; D062727:Coxsackie and Adenovirus Receptor-Like Membrane Protein; D011991:Receptors, Virus; D051178:alpha Catenin