Human epidermal receptor-2 expression in prostate cancer.
OBJECTIVE
Efforts to conclusively establish that human epidermal receptor (HER)-2 overexpression is important to androgen-dependent carcinoma of the prostate (AD-CaP) or to progression to androgen independence (AI-CaP) have failed because of variability in tissue procurement, antibodies, immunostaining procedures, and assessment methods. However, because some in vitro and animal model data correlate HER-2 overexpression with progression to androgen independence, trials of agents that target the HER-2 receptor are under way. To clarify human tumor findings, we studied HER-2 expression at the gene (DNA), mRNA, and protein levels in well-characterized CaP specimens.


METHODS
Fifty AD-CaP and 25 AI-CaP specimens from similar numbers of Caucasian and African Americans were immunostained for HER-2 receptor. HER-2 mRNA levels were measured using real-time fluorescence quantitative PCR in patients for whom frozen specimens were available. HER-2 amplification was evaluated using fluorescent in situ hybridization.


RESULTS
HER-2 receptor immunostained in 52% of androgen-dependent and one (4%) androgen-independent tumor. HER-2 immunostaining was not related to age, race, serum prostate-specific antigen levels, or pathologic stage and Gleason grade. HER-2 overexpression was not detected in AI-CaP at the mRNA or gene level. Mean HER-2 mRNA expression was higher (P < 0.05) in AD-CaP than AI-CaP (22,080 versus 15,496 HER-2 copies). HER-2 was not amplified in any of 20 AD-CaP or 19 AI-CaP specimens.


CONCLUSIONS
HER-2 protein and message overexpression and HER-2 amplification were not found in AI-CaP.
Calvo
Benjamin F
BF
Department of Surgery, Divisions of Surgical Oncology, University of North Carolina-Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.
Levine
Aaron M
AM
Marcos
Mavie
M
Collins
Qu F
QF
Iacocca
Mary V
MV
Caskey
Laura S
LS
Gregory
Christopher W
CW
Lin
Yuhua
Y
Whang
Young E
YE
Earp
H Shelton
HS
Mohler
James L
JL
D000728:Androgens / Q000378:metabolism; D002277:Carcinoma / Q000378:metabolism*; D018450:Disease Progression; D018734:Genes, erbB-2 / Q000235:genetics*; D006801:Humans; D007150:Immunohistochemistry; D017404:In Situ Hybridization, Fluorescence; D008024:Ligands; D008297:Male; D016133:Polymerase Chain Reaction; D011471:Prostatic Neoplasms / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000096:biosynthesis* / Q000502:physiology; D020133:Reverse Transcriptase Polymerase Chain Reaction
D000728:Androgens; D008024:Ligands; D012333:RNA, Messenger; D018719:Erb-b2 Receptor Tyrosine Kinases