Alpha-Methylacyl-CoA racemase catalyzes the racemization of alpha-methyl, branched carboxylic coenzyme A thioesters.
It is overexpressed in a variety of neoplasms, such as prostate and colon cancer.
Dr Russell Dorer and colleagues evaluated alpha-methylacyl-CoA racemase expression in the metaplasia-dysplasia-carcinoma sequence in Barrett's, ulcerative colitis, and Crohn's.
The researchers determined whether its expression can be used to detect dysplastic epithelium in these conditions.
The research team immunostained 134 routinely processed biopsy and/or resection specimens from 134 patients with Barretts.
Immunostainings in 14 specimens were indefinite for dysplasia, 16 were low-grade dysplasia, and 32 were high-grade dysplasia.
The team also immunostained 36 invasive adenocarcinoma, and 74 specimens from 74 patients with inflammatory bowel disease (IBD).
|Alpha-methylacyl-CoA racemase was expressed in 81% with high-grade dysplasia|
|American Journal of Surgical Pathology|
The researchers immunostained the specimens with a monoclonal alpha-methylacyl-CoA racemase antibody.
The degree of cytoplasmic staining in all cases was evaluated in a blinded fashion according to a grading system.
In patients with Barrett's, alpha-methylacyl-CoA racemase was not expressed in any negative foci but was increased in foci of low-grade dysplasia by 38%.
The team found that alpha-methylacyl-CoA racemase was expressed in 81% with high-grade dysplasia, and 72% in invasive adenocarcinoma.
The researchers noted that 23% of indefinite for dysplasia foci from 3 Barrett's Esophagus patients were only focally positive.
However, 1 of these 3 patients had follow-up information available, and had developed invasive adenocarcinoma subsequently.
Similarly, in patients with IBD, the team noted that alpha-methylacyl-CoA racemase was not expressed in any foci considered negative for dysplasia.
It was significantly increased in 96% of foci with low-grade dysplasia, 80% with high-grade dysplasia, and 71% with invasive adenocarcinoma.
Only 14% of indefinite for dysplasia focus from 1 patient was focally positive.
The sensitivity for the detection of low-grade dysplasia and high-grade dysplasia in Barrett's and IBD was 38% and 81%, and 96% and 80%, respectively.
The researchers observed that the specificity was 100% for both Barrett's Esophagus and IBD.
Dr Dorer's team concludes, “Alpha-methylacyl-CoA racemase is involved in the neoplastic progression in Barrett's Esophagus and IBD.”
“The high degree of specificity of alpha-methylacyl-CoA racemase for dysplasia/carcinoma in Barrett's Esophagus and IBD suggests that it may be useful to detect neoplastic epithelium in these conditions.”