title: Correlation of AR, EGFR, and HER2 Expression Levels in Prostate Cancer: Immunohistochemical Analysis and Chromogenic In Situ Hybridization.
abstract: OBJECTIVE
  The androgen receptor (AR) plays a central role in prostate cancer. Evidence from several groups indicates that epidermal growth factor receptor (EGFR) and human epidermal growth factor receptor 2 (HER2) may enhance AR activity in prostate cancer cell lines. This study was designed to investigate the protein expression of AR, EGFR, and HER2 and to determine whether the EGFR and HER2 genes are amplified in prostate cancer tissues.
  
  
  METHODS
  The protein expression levels of AR, EGFR, and HER2 in a tissue microarray block of 66 prostate cancer samples were investigated by immunohistochemical analysis and chromogenic in situ hybridization was used to determine whether the EGFR and HER2 genes were amplified in these tissues.
  
  
  RESULTS
  The AR and EGFR proteins were expressed in 59.1% and 40.9% of prostate cancers, respectively, but their expression levels were not significantly associated with clinicopathologic factors. Of the cases in which tissues were negative for EGFR protein expression, 69.2% were positive for AR protein expression; however, AR protein expression was significantly reduced (44.4%) in tissues in which EGFR protein was expressed. HER2 expression was detected in only 1 case (1.5%). No amplification of the EGFR or HER2 genes was found in prostate cancer specimens.
  
  
  CONCLUSIONS
  This study was limited by small number of subjects, but it can still be inferred that the expression levels of the AR and EGFR proteins are inversely correlated in prostate cancer patients. The potential utility of EGFR and HER2 as prognostic factors or therapeutic targets warrants further study.
authors.affiliation: Department of Pathology, Chung-Ang University College of Medicine, Seoul, Korea.
authors.forename: Kwang Hyun
authors.initials: KH
authors.lastname: Baek
authors.forename: Min Eui
authors.initials: ME
authors.lastname: Hong
authors.forename: Yoon Yang
authors.initials: YY
authors.lastname: Jung
authors.forename: Chung Hun
authors.initials: CH
authors.lastname: Lee
authors.forename: Tae Jin
authors.initials: TJ
authors.lastname: Lee
authors.forename: Eon Sub
authors.initials: ES
authors.lastname: Park
authors.forename: Mi Kyung
authors.initials: MK
authors.lastname: Kim
authors.forename: Jae Hyung
authors.initials: JH
authors.lastname: Yoo
authors.forename: Soo Whan
authors.initials: SW
authors.lastname: Lee