Increased translocator protein (TSPO) mRNA levels in colon but not in rectum carcinoma

Background: The peripheral-type benzodiazepine receptor or translocator protein (TSPO) is an 18-kDa protein involved in cell proliferation and apoptosis. TSPO was shown to be overexpressed in malignant tumors and cancer cell lines, correlating with enhanced malignant behavior. The present study analyzed the role of TSPO in patients with colorectal carcinomas. Methods: Tumor tissues and corresponding normal mucosa from 55 patients who underwent resection for colorectal carcinomas were analyzed for TSPO expression in correlation to GAPDH expression (glyceraldehyde-3-phosphate dehydrogenase) using a multiplex RT-PCR assay. Results: TSPO was overexpressed in 67% of the tumors in comparison to corresponding normal mucosa, and positivity as well as expression levels in colon carcinomas were significantly higher than in the rectum carcinomas. In contrast, TSPO expression was not different in intermediate versus high-grade tumors or in lymph node-positive versus-negative patients. Conclusion: The differences in TSPO expression between colon and rectum carcinoma may imply that these tumors are of different biological behavior. Copyright (c) 2007 S. Karger AG, Basel.