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Open Access Research article

The HOPE fixation technique - a promising alternative to common prostate cancer biobanking approaches

Martin Braun4, Roopika Menon4, Pavel Nikolov4, Robert Kirsten4, Karen Petersen1, David Schilling2, Christina Schott3, Sibylle Gündisch3, Falko Fend1, Karl-Friedrich Becker3 and Sven Perner14*

Author Affiliations

1 Institute of Pathology, Comprehensive Cancer Center, University Hospital of Tuebingen, Tuebingen, Germany

2 Department of Urology, Comprehensive Cancer Center, University Hospital of Tuebingen, Tuebingen, Germany

3 Institute of Pathology, Technical University of Munich, Munich, Germany

4 Institute of Prostate Cancer Research, Institute of Pathology, University Hospital Bonn, Sigmund-Freud-Straße 25, 53127 Bonn, Germany

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BMC Cancer 2011, 11:511  doi:10.1186/1471-2407-11-511

Published: 7 December 2011

Abstract

Background

The availability of well-annotated prostate tissue samples through biobanks is key for research. Whereas fresh-frozen tissue is well suited for a broad spectrum of molecular analyses, its storage and handling is complex and cost-intensive. Formalin-fixed paraffin-embedded specimens (FFPE) are easy to handle and economic to store, but their applicability for molecular methods is restricted. The recently introduced Hepes-glutamic acid-buffer mediated Organic solvent Protection Effect (HOPE) is a promising alternative, which might have the potential to unite the benefits of FFPE and fresh-frozen specimen. Aim of the study was to compare HOPE-fixed, FFPE and fresh-frozen bio-specimens for their accessibility for diagnostic and research purposes.

Methods

10 prostate cancer samples were each preserved with HOPE, formalin, and liquid nitrogen and studied with in-situ and molecular methods. Samples were H&E stained, and assessed by immunohistochemistry (i.e. PSA, GOLPH2, p63) and FISH (i.e. ERG rearrangement). We assessed DNA integrity by PCR, using control genes ranging from 100 to 600 bp amplicon size. RNA integrity was assessed through qRT-PCR on three housekeeping genes (TBP, GAPDH, β-actin). Protein expression was analysed by performing western blot analysis using GOLPH2 and PSA antibodies.

Results

Of the HOPE samples, morphologic quality of H&E sections, immunohistochemical staining, and the FISH assay was at least equal to FFPE tissue, and significantly better than the fresh-frozen specimens. DNA, RNA, and protein analysis of HOPE samples provided similar results as compared to fresh-frozen specimens. As expected, FFPE-samples were inferior for most of the molecular analyses.

Conclusions

This is the first study, comparatively assessing the suitability of these fixation methods for diagnostic and research utilization. Overall, HOPE-fixed bio-specimens combine the benefits of FFPE- and fresh-frozen samples. Results of this study have the potential to expand on contemporary prostate tissue biobanking approaches and can serve as a model for other organs and tumors.

Keywords:
HOPE technique; HOPE fixation; Prostate cancer