Mod Pathol, 20(4), 467–473
April, 2007

A variant TMPRSS2 isoform and ERG fusion product in prostate cancerwith implications for molecular diagnosis.

Jacques Lapointe, Young H. Kim, Melinda A. Miller, Chunde Li, Gulsah Kaygusuz, van de Rijn, Matt, David G. Huntsman, James D. Brooks, Jonathan R. Pollack

<p>Prostate cancer is the most commonly diagnosed cancer among men in the United States. Recently, fusion of <em>TMPRSS2</em> with ETS family oncogenic transcription factors has been identified as a common molecular alteration in prostate cancer, where most often the rearrangement places <em>ERG</em> under the androgen-regulated transcriptional control of <em>TMPRSS2</em>. Here, we carried out rapid amplification of cDNA ends (RACE) on a prostate cancer specimen carrying an atypical aberration discovered by array-based comparative genomic hybridization (array CGH), suggesting an alternative fusion partner of <em>ERG</em>. We identified novel transcribed sequences fused to <em>ERG</em>, mapping 4 kb upstream of the <em>TMPRSS2</em> start site. The sequences derive from an apparent second <em>TMPRSS2</em> isoform, which we found also expressed in some prostate tumors, suggesting similar androgen-regulated control. In a reverse transcription-polymerase chain reaction (RT-PCR)-based survey of 63 prostate tumor specimens (54 primary and nine lymph node metastases), 44 (70%) cases expressed either the known or novel variant <em>TMPRSS2</em>-<em>ERG</em> fusion, 28 (44%) expressed both, 10 (16%) expressed only the known, and notably six (10%) expressed only the variant isoform fusion. In this specimen set, the presence of a <em>TMPRSS2</em>-<em>ERG</em> fusion showed no statistical association with tumor stage, Gleason grade or recurrence-free survival. Nonetheless, the discovery of a novel variant <em>TMPRSS2</em> isoform-<em>ERG</em> fusion adds to the characterization of ETS-family rearrangements in prostate cancer, and has important implications for the accurate molecular diagnosis of <em>TMPRSS2</em>-<em>ETS</em> fusions.</p>

All Publications