p504S/Alpha-Methylacyl-CoA Racemase (AMACR)

P504S (AMACR) is an essential enzyme in the β-oxidation of branched-chain fatty acids. Recently, P504S was identified through cDNA library subtraction and microarrays in malignant prostate tissues. High expression of P504S protein is found in prostatic adenocarcinoma but not in benign prostatic tissue by immunohistochemical staining in paraffin-embedded tissues. The expression of P504S is also detected in two premalignant lesions of the prostate: high-grade prostatic intraepithelial neoplasia (PIN) and atypical adenomatous hyperplasia. Using P504S as a positive marker along with basal cell staining (34 βE12 or P63) as a negative marker could help to confirm the diagnosis of small focus of prostate carcinoma on needle biopsy.