Topoisomerase IIα in Wilms’ tumour: gene alterations and immunoexpression
- 1Department of Pathology, University of Chicago, Chicago, Illinois, USA
- 2Department of Hematology and Oncology, University of Chicago
- 3Department of Health Studies, University of Chicago
- 4Department of Pediatrics, University of Chicago
- 5Van Andel Research Institute, Grand Rapids, Michigan, USA
- 6Department of Pathology, Northwestern Memorial Hospital, Northwestern University, Feinberg School of Medicine, Chicago
- Correspondence to: X J Yang Department of Pathology, Feinberg 7-334, Northwestern Memorial Hospital, Northwestern University, Feinberg School of Medicine, 251 E Huron Street, Chicago, IL 60611,USA; xyang{at}northwestern.edu
- Accepted 24 November 2005
- Published Online First 23 March 2006
Abstract
Background: Topoisomerase IIα (topoIIα) is an essential enzyme gene in regulating DNA structure and cell proliferation and is encoded by the TOP2A. Using cDNA microarray analysis, TOP2A has been reported to be one of the top genes overexpressed in Wilms’ tumour.
Aim: To evaluate the role of TopoIIα in Wilms’ tumorigenesis and its prognostic value.
Methods:TOP2A gene copy numbers were determined using the fluorescence in situ hybridisation technique, and protein expression levels of TopoIIα by immunostaining in 39 samples of primary and 18 samples of metastatic Wilms’ tumour.
Results:TOP2A gene amplification was detected only in anaplastic Wilms’ tumours, and none of the Wilms’ tumours showed deletion of the TOP2A gene. TopoIIα protein overexpression was detected in 97% of Wilms’ tumours, and correlated strongly with proliferation, as measured by Ki-67 (r = 0.85). The high TopoIIα expression was associated with the presence of vascular invasion, prominent apoptosis, metastases and adverse clinical outcomes (p<0.05).
Conclusions: Our findings suggest that TopoIIα overexpression in Wilms’ tumours is caused by a change at the transcription level, except for anaplastic Wilms’ tumours, in which gene amplification was present. High levels of TopoIIα protein are correlated with tumour aggressiveness. The assessment of TopoIIα expression in Wilms’ tumour may have prognostic value.
- FISH, fluorescence in situ hybridisation
- IHC, immunohistochemistry
- PFS, progression-free survival
- TMA, tissue microarray
- topoIIα, topoisomerase IIα
Footnotes
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Published Online First 23 March 2006
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Competing interests: None declared.
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Presented in abstract form at the 95th Annual Meeting of the United States and Canadian Academy of Pathology, San Antonio, March 2005.
