Present
in 50-70% of all prostate carcinomas, ERG oncoprotein expression has been shown
to be a highly specific marker for prostate cancer. Given the lack of ERG
expression in a wide variety of normal epithelial tissues and tumors, and its
robust presence in prostatic adenocarcinoma, detection of ERG by IHC is a
valuable tool for diagnosing prostate cancer or determining prostatic
origin.
In
prostate cancer, the ERG gene locus may undergo a chromosomal translocation with
the androgen-regulated transmembrane protease serine 2 (TMPRSS2) gene, resulting
in the expression of an TMPRSS2-ERG oncoprotein; a new diagnostic marker of
prostate cancer. The TMPRSS2-ERG fusion has been found to be the most common
proto-oncogene present in prostate cancers, occurring in 50-70% of cases.
Molecular methods (FISH, bDNA) have shown a strong correlation between
TMRPSS2-ERG rearrangement status and ERG expression, as detected by IHC.
Developed
in collaboration with scientists at the Center for Prostatic Disease Research
and the Henry M. Jackson Foundation for the Advancement of Military Medicine,
the anti-ERG antibody [9FY] offers a superior method for ERG detection by IHC,
with >99.9% specificity. Importantly, the 9FY antibody does not stain
lymphocytes, offering easier interpretation and increasing diagnostic
confidence. The strong correlation between ERG-positive prostatic
intraepithelial neoplasia (PIN) and associated ERG-positive carcinoma (96.5%)
suggests that in cases of ERG-positive PIN in biopsy samples, carcinoma may be
indicated and additional diagnostic follow-up may be prudent.
Given
the ease of performing IHC vs. FISH, ERG protein expression in formalin fixed
paraffin embedded tissues is an exceptionally useful tool for the routine
determination of ERG rearrangement status and diagnosis of prostate
adenocarcinoma.