Frequent discordance between ERG gene rearrangement and ERG protein expression in a rapid autopsy cohort of patients with lethal, metastatic, castration-resistant prostate cancer

Aaron M. Udager, Yang Shi, Scott A. Tomlins, Ajjai Alva, Javed Siddiqui, Xuhong Cao, Kenneth J. Pienta, Hui Jiang, Arul M. Chinnaiyan, Rohit Mehra

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BACKGROUND. ERG rearrangements in localized prostate cancer can be detected with high sensitivity and specificity by immunohistochemistry (IHC). However, recent data suggest that ERG IHC may be less sensitive for ERG rearrangements in castration-resistant prostate cancer (CRPC). Thus, we sought to examine ERG protein expression in a cohort of rapid autopsy patients with lethal metastatic CRPC (mCRPC). METHODS. A tissue microarray (TMA) of tumor sites from these patients was evaluated for ERG, prostate-specific antigen (PSA), and androgen receptor (AR) expression by IHC and correlated with ERG rearrangement status by fluorescent in situ hybridization (FISH). IHC was scored as the product of tumor cell staining intensity (0-3) and percentage of cells positive (0-100) (overall product score range = 0-300). RESULTS. All 16 (100%) ERG rearrangement negative (ERGneg) patients were also negative for ERG tumor cell expression (i.e., IHC product score = 0). Of the 10 ERG rearrangement positive (ERG pos) patients, two (20%) were completely negative for ERG tumor cell expression, while eight (80%) had weak ERG expression (median IHC product score = 5-110). Of these eight ERGpos patients, five (63%) had at least one tumor site without any detectable ERG expression. For a given ERGpos patient, ERG expression varied both between and within tumor sites; AR and PSA expression also varied between tumor sites, and there was no significant correlation between ERG and AR or PSA expression. CONCLUSIONS. These data reveal frequent discordance between ERG IHC and ERG FISH in ERGpos patients from this unique cohort of heavily treated lethal mCRPC.

Original languageEnglish (US)
Pages (from-to)1199-1208
Number of pages10
Issue number12
StatePublished - Sep 2014



  • androgen receptor (AR)
  • fluorescent in situ hybridization (FISH)
  • immunohistochemistry (IHC)
  • rapid autopsy

ASJC Scopus subject areas

  • Oncology
  • Urology

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