Differential expression of desmosomal plakophilins in various types of carcinomas: correlation with cell type and differentiation.
Plakophilins (PKPs) are a set of 3 constitutive armadillo repeat proteins of the desmosomal plaque, termed PKP 1, PKP 2, and PKP 3, which have been shown to be functionally relevant for desmosomal adhesion. We have performed a systematic immunohistochemical study of the 3 PKPs in oral and pharyngeal squamous cell carcinomas (SqCCs; n = 40); colorectal, pancreatic, and prostate adenocarcinomas (n = 31), and hepatocellular carcinomas (HCCs; n = 8). In SqCCs, PKP 1 and PKP 3 revealed common desmosome-type immunostaining, their expression level being inversely correlated with the degree of malignancy. Instead, staining for PKP 2 was limited. In contrast, all adenocarcinomas contained PKP 2 and-often abundantly-PKP 3 in desmosome-typical pattern, whereas PKP 1 was expressed only in prostate tumors. The presence of PKP 3 in adenocarcinomas was confirmed by immunoblotting. In HCCs, only PKP 2 was detected. Under certain staining conditions, focal nuclear immunoreactivity for PKP 1 was observed in some SqCCs and HCCs. Our results, which are inconsistent with previously published data to some extent, indicate a principal preservation of the cell type and differentiation-related expression patterns of PKPs in normal epithelia. For PKP 1, a suppressor function of malignant behavior seems conceivable, whereas the putative functional significance of its occurrence in tumor cell nuclei requires further studies.
Schwarz
Juliane
J
Department of Pathology, Philipps-University of Marburg Medical School, D-35033 Marburg, Germany.
Ayim
Amma
A
Schmidt
Ansgar
A
Jäger
Stephanie
S
Koch
Sabine
S
Baumann
Renate
R
Dünne
Anja A
AA
Moll
Roland
R
D000230:Adenocarcinoma / Q000378:metabolism* / Q000473:pathology; D003896:Desmosomes / Q000378:metabolism*; D006801:Humans; D015151:Immunoblotting; D007124:Immunoenzyme Techniques; D008297:Male; D009369:Neoplasms / Q000378:metabolism* / Q000473:pathology; D051191:Plakophilins / Q000378:metabolism*
D051191:Plakophilins