Expression of Alpha - Methylacyl - Coenzyme A Racemase (AMACR) in Colorectal Neoplasia.

INTRODUCTION: Red meat and dairy products have been implicated in colonic cancers. They are rich in branched chain fatty acids which require an enzyme Alpha-Methylacyl-Coenzyme A Racemase (AMACR) for their oxidation. Increased expression of AMACR in colorectal premalignant lesions and carcinomas suggests its possible role in carcinogenesis.

AIM: To study the expression of AMACR in colorectal neoplasia and its correlation with the histological grade, stage and nodal status of colorectal malignancy.

MATERIALS AND METHODS: All cases of colorectal neoplasms were included in the study. AMACR expression was studied in 56 cases which included 44 cases of adenocarcinoma and 12 cases of adenoma and a normal colonic mucosal tissue was used as a control. A tissue microarray was prepared by manual method. AMACR expression was studied by Immunohistochemistry (IHC) and it was correlated with the grade, stage and nodal status of the cancer. Chi-square test was used for analysis or results. The p-value of <0.05 was considered significant.

RESULTS: Out of 12 cases of adenoma 25% (3/12) were negative; 50% (6/12) showed poor expression, 25% (3/12) had moderate expression and none showed strong expression. Nearly, 34.1% (15/44) case of carcinoma were negative; 45.45% (20/44) had poor; 13.63% (6/44) had moderate and 6.81% (3/44) had a strong expression. Normal colonic tissue showed no expression. There was no significant difference of AMACR expression between adenoma and carcinoma cases. AMACR expression was found to be increased in low grade carcinomas (G1 and G2). G1 showed AMACR positivity in 62% cases and G2 showed 71.4% positivity. No association was found between AMACR expression and different American Joint Committee on Cancer (AJCC) stages and nodal status of CRC.

CONCLUSION: Increased expression of AMACR in adenomas and carcinomas as compared to non-neoplastic epithelium of colon implies that, it plays a role in colorectal neoplasia. Decreased expression of AMACR in high grade carcinomas suggests its role in differentiation of the tumour.