[808] Improved Method of Detecting the ERG Gene Rearrangement in Prostate Cancer Using Combined Dual-Color Chromogenic and Silver In-Situ Hybridization

Martin Braun, Julia Stomper, Diana Boehm, Wenzel Vogel, Veit Scheble, Nicolas Wernert, Zaki Shaikibrahim, Falko Fend, Glen Kristiansen, Sven Perner. University Hospital of Bonn, Bonn, Germany; University Hospital of Tuebingen, Tuebingen, Germany

Background: The recently detected TMPRSS2-ERG fusion revealed as a recurrent and prevalent prostate cancer (PCa) specific event, which potentially qualifies it for clinical utilizations. To detect this alteration, fluorescence in-situ hybridization (FISH) is the method of choice. However, FISH harbors some disadvantages for widespread adoption in clinical practice. Subsequently, the chromogenic in-situ hybridization (CISH), that uses organic chromogens, and the enzymatic metallography silver in-situ hybridization (SISH) emerged as promising bright-field alternatives. Compared to CISH, SISH signals are very distinct and superior with regard to signal clarity and resolution, but rule out a multi-color protocol. However, the precise localization of genomic targets using a dual-color approach is indispensable for gene break-apart and fusion assays. In order to bridge this gap, we aimed to develop a dual-colour combined CISH and SISH (CS-ISH) gene break-apart assay on the example of the ERG gene commonly rearranged in PCa.
Design: On the basis of the ERG break-apart FISH assay, we established a dual-colour ERG break-apart CS-ISH assay and compared these results with those obtained by FISH. We assessed 178 PCa and 10 benign specimens for their ERG rearrangement status applying a dual-colour FISH and CS-ISH ERG break-apart assay on consecutive sections.
Results: We observed a highly significant concordance (97,7%) between FISH-based and CS-ISH-based results (Pearson's correlation coefficient 0.955, P<0.001).
Conclusions: Our findings demonstrate that the ERG rearrangement status can reliably be assesed by CS-ISH. Further, we confirm that the CS-ISH technique combines the accuracy and precision of FISH with the ease of bright field microscopy. We developed a tool which allows a much broader spectrum of applicants to study the biological role and clinical utilization of ERG rearrangements in PCa. Moreoever, our study is the first proof-of-principle for bright-field CS-ISH gene fusion or break-apart assays.
Category: Genitourinary (including renal tumors)

Tuesday, March 20, 2012 8:00 AM

Platform Session: Section A, Tuesday Morning


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