α-methylacyl-CoA racemase (AMACR)
AMACR (P504S protein, 48 kDa) plays a role in the beta-oxidation of branched-chain fatty acids and their derivatives. AMACR is found in mitochondria and peroxisomes of numerous tissues such as prostate, liver, biliary tract, kidney and lung. Using immunohistochemistry, non-neoplastic prostate show a weak or focal staining reaction in about 20% of the cases (Fig. 1B). The reactivity tends to decrease with age but the correlation coefficient is low.
A diffuse staining pattern for AMACR has been found in more than 90% of prostate carcinomas irrespective of Gleason score (Fig. 1C-E). Particularly foamy, pseudohyperplastic and atrophic variants of carcinoma may be negative. In prostatic intraepithelial neoplasia (PIN), the positive rate of AMACR ranges from 13% to 72%.
AMACR is mainly used in prostate lesions. Since negative staining for high molecular weight cytokeratin (HMW-CK) in atypical prostate glands may not be sufficient for a definitive diagnosis of malignancy, p63 may enhance the ability to diagnose limited prostate cancer. However, AMACR should always be used in conjunction with (HMW-CK) and/or p63. A cocktail staining is applicable. It is also important to note that AMACR positive glands in a prostate biopsy may represent seminal vesicle or periurethral glands.
rmAb clone 13H4 and pAbs CP200/PP200 and ab12498 have been used in optimal protocols. HIER is necessary.
Control tissue: A multitissue block containing both normal prostate, prostate in situ neoplasia (PIN) and prostate adenocarcinoma is appropriate.
Gologan A, Bastacky S, McHale T, Yu J, Cai C, Monzon-Bordonaba F, Dhir R. Age-Associated Changes in Alpha-Methyl CoA Racemase (AMACR) Expression in Nonneoplastic Prostatic Tissues. Am J Surg Pathol. 2005 Nov;29(11):1435-41.
O, Humphrey PA. p63/AMACR antibody cocktail restaining of prostate
needle biopsy tissues after
Woda BA. Diagnostic utility of alpha-methylacyl CoA racemase (P504S)
on prostate needle
LP, Chinnaiyan AM, Shah RB. Comparison of monoclonal antibody
(P504S) and polyclonal antibody to alpha
Jasani B. Diagnostic utility of immunohistochemistry in