Significance of overexpression of alpha methylacyl-coenzyme A racemase in hepatocellular carcinoma

BACKGROUND: alpha-Methylacyl-CoA racemase (AMACR), an immunomarker for prostatic adenocarcinoma, has been shown to be expressed in a variety of other neoplasms. This study aims to evaluate immunohistochemical expression of the AMACR in neoplastic and nonneoplastic liver lesions, and assess its value in the diagnosis of hepatocellular carcinoma (HCC). METHODS: Formalin-fixed paraffin-embedded tissue sections of 51 HCC (14 well, 22 moderately and 15 poorly differentiated), 9 hepatocellular adenoma (HCA), 48 cirrhotic nodules (CN) and 16 normal liver tissues (NLT) were immunostained for AMACR. RESULTS: Expression of AMACR is significantly enhanced in HCC tissue compared with non-HCC tissue. High expression of AMACR was found in 82% of HCC including 86% of well-differentiated HCC. In contrast, only 11% of HCA, 13% of CN and 6% of NLT showed high expression for AMACR. Clinicopathological evaluation showed a significant correlation between AMACR expression and venous invasion and capsular invasion by HCC. CONCLUSION: Our results suggest that AMACR staining may serve as a useful marker for the differential diagnosis of well-differentiated HCC from HCA. Increased AMACR expression and its association with tumor venous invasion suggest that AMACR may play a role in HCC development and progression.