Detection of Merkel Cell Polyomavirus in Chronic Lymphocytic Leukemia Cells by Fluorescent In Situ Hybridization (FISH).
Axel zur Hausen, N Deepa Pantulu, Christian P Pallasch, Anna Kordelia Kurz, Anke Haugg, Ahmad Kassem, Lukas Frenzel, Sebastian Sodenkamp, Hans Michael Kvasnicka, Ernst-Jan M Speel, Clemens M Wendtner. Maastricht University Medical Center, Maastricht, Netherlands; University Hospital Freiburg, Germany; University Hospital Cologne, Germany
Background: Merkel cell polyomavirus (MCPyV) is detected in approximately 80% of Merkel cell carcinomas (MCC). A number of previous studies have shown that MCC patients are at a significantly increased risk to develop chronic lymphocytic leukemia (CLL) and vice versa. Until recently, clonal integration and truncating mutations of the Large T antigen (LTAg) of MCPyV were restricted to MCC. We have recently reported the presence of the MCPyV in highly purified tumor cells of CLL (n= 19/70, 27.1%) (Blood. 2010 Sep 3). Of these, six revealed revealed a novel 246bp deletion in the helicase gene of the large T antigen (LTAg). The presence of MCPyV was confirmed by immunohistochemistry.
Design: Here we aimed to determine the presence of MCPyV by FISH analysis in CLL cells in order to evaluate whether MCPyV was integrated or episomal. For this purpose we performed FISH analysis as previously described (Int J Cancer. 2005 Jun 20;115(3):419-28) using MCPyV genome as FISH probe. We tested 2 of the previously reported MCPyV positive CLL cases (EDTA decalcified bone marrow trephines) and MCPyV positive MCC (n= 5). In addition, we tested MCPyV negative tumors, e.g. breast and colon cancers. All tissues were formaline fixed and paraffine embedded.
Results: Specific MCPyV DNA by FISH analysis was detected in the nuclei of MCPyV-positive CLL and MCC cells. In contrast to MCC, the FISH signals of the CLL cases revealed more granular signals. However, the CLL specimens derived from EDTA decalcified bone marrow trephines in contrast to the non decalcified specimens of MCCs. No signals were obtained by MCPyV FISH in breast or colon cancer specimens.
Conclusions: The specific detection of MCPyV in CLL cells further supports our previous report of a possible involvement of MCPyV in a significant subset of CLL. The specific but rather granular nuclear FISH signals in MCPyV positive CLL cells point to an episomal presence of MCPyV in CLL cells. Currently we are optimizing the MCPyV FISH protocol including RNase pretreatments in order to test the granular FISH results and to assess further CLL cases for the presence of MCPyV.
Wednesday, March 2, 2011 9:30 AM
Poster Session V # 165, Wednesday Morning