Cardiac Myxomas and Plakophilin-2 Positive Cell-Cell Junctions: A Possible Novel Immunocytochemical Marker
S Rizzo, C Basso, G Thiene, S Rickelt, M Barth, WW Franke. University of Padua Medical School, Padua, Italy; German Cancer Research Center, Heidelberg, Germany
Background: As the histogenesis and the differential diagnosis of subforms of cardiac myxomas are still controversial subjects, we applied immunocytochemistry using molecular markers for cytoskeletal and junctional proteins, to improve the cell biological basis for myxoma characterization.
Design: We studied 21 cardiac myxomas (10 M, 11F; mean age 56,5±17,13). To examine the mesenchymal differentiation state and the junction proteins antisera against vimentin, desmin, actin, myosin or keratin 8 and 18; N-and E-cadherin, cadherin-11, VE-cadherin, α- and β-catenin, p120, vinculin, α-actinin, afadin, p0071, ARVCF, desmoplakins-1,-2, plakophilin-1,-2,-3, desmocollins1,3 and desmogleins1,2,3 were used.
Results: All myxoma cells were positive for vimentin and also contained smooth muscle α-actin. The tumor cells were connected by adhering junctions (AJs) positive for the arm-repeat proteins β-catenin, plakoglobin, protein ARVCF and protein p0071, as well as for α-catenin and afadin. Surprisingly, however, a considerable proportion of the myxoma cells were connected by AJs that in addition also contained plakophilin-2 (PKP2), generally known as an obligatory component of desmosomes of proliferatively active epithelial and carcinoma tissues and cell cultures.
Conclusions: The existence of a subpopulation of PKP2-positive AJs has recently also been noted in certain other soft tissue tumors and mesenchymally derived cells of high proliferative activity. These findings are also important in view of the architectonically organizing role of PKP2 in diverse cell types. These results are discussed in relation to current concepts of origins of cardiac myxomas, the potential value of a differential diagnosis of molecularly defined myxoma subclasses and the molecular functions of PKP2.
Wednesday, March 24, 2010 1:00 PM
Poster Session VI # 25, Wednesday Afternoon