Premium
Close localization of DAP‐kinase positive tumour‐associated macrophages and apoptotic colorectal cancer cells
Author(s) -
SchneiderStock R,
Kuester D,
Ullrich O,
Mittag F,
Habold C,
Boltze C,
Peters B,
Krueger S,
Hintze C,
Meyer F,
Hartig R,
Roessner A
Publication year - 2006
Publication title -
the journal of pathology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.964
H-Index - 184
eISSN - 1096-9896
pISSN - 0022-3417
DOI - 10.1002/path.1951
Subject(s) - fas ligand , cancer research , biology , apoptosis , dna methylation , kinase , carcinogenesis , microbiology and biotechnology , protein kinase a , programmed cell death , protein kinase r , cyclin dependent kinase 2 , cancer , gene expression , gene , biochemistry , genetics
The death‐associated protein kinase (DAP‐kinase) is a cytoskeleton‐associated protein crucially involved in the induction of early apoptotic pathways. Aberrant hypermethylation of the DAP‐kinase promoter plays a major role in tumorigenesis. We aimed to investigate the inactivation of DAP‐kinase and its association with apoptotic cell death in 94 colorectal carcinomas. DAP‐kinase promoter hypermethylation and mRNA expression were investigated using methylation‐specific PCR and real‐time RT‐PCR, respectively. The expression of DAP‐kinase, Fas, and Fas‐ligand (FasL) proteins was studied by immunohistochemistry and immunofluorescence. Apoptosis of tumour cells was investigated using the TUNEL assay. DAP‐kinase was expressed in tumour cells and tumour‐invading macrophages and was closely associated with high numbers of apoptotic tumour cells. DAP‐kinase expression co‐localized with FasL overexpression in tumour‐associated macrophages, and aberrant promoter hypermethylation was verified in more than 50% of carcinomas. There was a tendency for proximal tumours to show DAP‐kinase promoter methylation more frequently ( p = 0.07). Promoter methylation resulted in a decrease or loss of DAP‐kinase protein expression in tumour cells and tumour‐associated macrophages. Simultaneously, a decreased apoptotic count and loss of Fas/FasL expression was observed in tumour cells. Our study is the first to demonstrate DAP‐kinase expression in invading tumour‐associated macrophages in colorectal cancer. The presence of similar expression levels of DAP‐kinase in tumour cells and associated macrophages, and their dependence on the promoter methylation status of the tumour cells, suggests cross talk between these cell types during apoptotic cell death. Copyright © 2006 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.