A novel kind of tumor type-characteristic junction: plakophilin-2 as a major protein of adherens junctions in cardiac myxomata.
Using novel antibodies of high avidity to--and specificity for--the constitutive desmosomal plaque protein, plakophilin-2 (Pkp2), in a systematic study of the molecular composition of junctions connecting the cells of soft tissue tumors, we have discovered with immunocytochemical, biochemical and electron microscopical methods, a novel type of adherens junctions in all 32 cardiac myxomata examined. These junctions contain cadherin-11 as their major transmembrane glycoprotein, which we could repeatedly show in colocalization with N-cadherin, anchored in a cytoplasmic plaque formed by α- and β-catenin, together with the further armadillo-type proteins plakoglobin, p120, p0071 and ARVCF. Surprisingly, all adherens junctions of these tumors contained, in addition, another major armadillo protein Pkp2, hitherto known as an obligatory and characteristic constituent of desmosomes in epithelium-derived tumors. We have not detected Pkp2 in a series of noncardiac myxomata studied in parallel. Therefore, we conclude that this acquisition of Pkp2, which we have recently also observed in some mesenchymally derived cells growing in culture, can also occur in tumorigenic transformations in situ. We propose to examine the marker value of Pkp2 in clinical diagnoses of cardiac myxomata and to develop Pkp2-targeted therapeutic reagents.
Rickelt
Steffen
S
Helmholtz Group for Cell Biology, German Cancer Research Center, Heidelberg, Germany.
Rizzo
Stefania
S
Doerflinger
Yvette
Y
Zentgraf
Hanswalter
H
Basso
Cristina
C
Gerosa
Gino
G
Thiene
Gaetano
G
Moll
Roland
R
Franke
Werner W
WW
D022005:Adherens Junctions / Q000737:chemistry* / Q000648:ultrastructure; D015703:Antigens, CD / Q000032:analysis; D051186:Armadillo Domain Proteins / Q000032:analysis; D014408:Biomarkers, Tumor / Q000032:analysis*; D015820:Cadherins / Q000032:analysis; D015815:Cell Adhesion Molecules / Q000032:analysis; D045744:Cell Line, Tumor; D051180:Desmoplakins / Q000032:analysis; D004591:Electrophoresis, Polyacrylamide Gel; D006338:Heart Neoplasms / Q000737:chemistry* / Q000648:ultrastructure; D006801:Humans; D007150:Immunohistochemistry; D008854:Microscopy, Electron; D009232:Myxoma / Q000737:chemistry* / Q000648:ultrastructure; D010750:Phosphoproteins / Q000032:analysis; D051191:Plakophilins / Q000032:analysis*; D051178:alpha Catenin / Q000032:analysis; D051176:beta Catenin / Q000032:analysis; D051185:gamma Catenin
C411307:ARVCF protein, human; D015703:Antigens, CD; D051186:Armadillo Domain Proteins; D014408:Biomarkers, Tumor; C050361:CDH2 protein, human; C495270:CTNNB1 protein, human; D015820:Cadherins; D015815:Cell Adhesion Molecules; D051180:Desmoplakins; C495292:JUP protein, human; C495337:PKP2 protein, human; C105677:PKP4 protein, human; D010750:Phosphoproteins; D051191:Plakophilins; D051178:alpha Catenin; D051176:beta Catenin; D051185:gamma Catenin; C086960:osteoblast cadherin