p120-catenin expression in human colorectal cancer.
Recent data suggest that p120-catenin plays a role in the regulation of functionality of E-cadherin, a protein essential for the establishment and maintenance of cell-cell contacts. Since dysfunction of intercellular adhesiveness is an alteration frequently observed in colon cancer we have studied the expression and distribution of p120-catenin in human colorectal tumors. In normal colon, p120-catenin was observed in the crypt and surface epithelium; the cells showed reactivity both in the membrane and in the cytosol. Thirteen primary tumors were examined for p120-catenin expression: they were graded as uniformly positives (+) (4); heterogeneous (+/-) (6), with a diminished expression, detected mainly in the cytosol; and negatives (-) (3). Although the number of tumors was low, the reduction in p120-catenin correlated with a larger size of the tumors (p = 0.038). Association of p120-catenin to the cytoskeleton was also determined in 5 tumors by detergent extraction and Western blot; this analysis shows that lack of reactivity in the membrane was accompanied by absence of p120-catenin in the cytoskeleton-associated fraction. Analysis of E-cadherin was performed in order to compare the distribution of this protein and p120-catenin. Although no complete correlation was found between the expression of both proteins (p = 0.077), our results showed that alterations in the level or distribution of p120-catenin were accompanied by lack of E-cadherin reactivity in the membrane, whereas absence of p120-catenin in the cytoskeleton fraction was associated with important decreases in the amount of E-cadherin in this same fraction. These results show that alterations in p120-catenin levels are a common event in colorectal tumors, and suggest that the distribution of this protein and E-cadherin is coordinately regulated.
Unitat de Biologia Cel.lular i Molecular, Institut Municipal d'Investigació Mèdica, Universitat Autònoma de Barcelona, Spain.
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Skoudy
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S
Gomez
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M
Fabre
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Garcia de Herreros
D000911:Antibodies, Monoclonal; D015153:Blotting, Western; D015820:Cadherins / Q000032:analysis; D051177:Catenins; D015815:Cell Adhesion Molecules / Q000032:analysis*; D002462:Cell Membrane / Q000737:chemistry; D015179:Colorectal Neoplasms / Q000737:chemistry* / Q000648:ultrastructure; D003599:Cytoskeleton / Q000737:chemistry; D005455:Fluorescent Antibody Technique; D006801:Humans; D007150:Immunohistochemistry; D010750:Phosphoproteins / Q000032:analysis*; D000095002:Delta Catenin
D000911:Antibodies, Monoclonal; D015820:Cadherins; D051177:Catenins; D015815:Cell Adhesion Molecules; D010750:Phosphoproteins; D000095002:Delta Catenin; C000722347:CTNND1 protein, human