Clinical Significance of Peroxisome Proliferator-Activated Receptor gamma and TRAP220 in Patients with Operable Colorectal Cancer

Purpose The peroxisome proliferator-activated receptor gamma (PPAR gamma) is a nuclear receptor that regulates expression of mediators of lipid metabolism and the inflammatory response. Thyroid hormone receptor-associated proteins 220 (TRAP220) is an essential component of the TRAP/Mediator complex. The objective of this study was to clarify whether PPAR gamma or TRAP220 are significant prognostic markers in resectable colorectal cancer (CRC). Materials and Methods A total of 399 patients who underwent curative resection for CRC were enrolled. We investigated the presence of PPAR gamma and TARP220 in CRC tissues and adjacent normal tissues by immunohistochemistry. Correlation between the expression of these factors and clinicopathologic features and survival was investigated. Results Median age of the patients was 63 years (range, 22 to 87 years), and median follow-up duration 61.1 months (range, 2 to 114 months). PPAR gamma and TRAP220 expression showed significant correlation with depth of invasion (p=0.013 and p=0.001, respectively). Expression of TRAP220 also showed association with lymph node metastasis and TNM stage (p=0.001). Compared with patients with TRAP220 negative tumors, patients with TRAP220 positive tumors had longer 5-year disease-free survival (DFS) tendency (p=0.051). Patients who were PPAR gamma positive combined with TRAP220 positive had a better 5-year DFS (64.8% vs. 79.3%, p=0.013). In multivariate analysis expression of both PPAR gamma and TRAP220 significantly affected DFS (hazard ratio, 0.620; 95% confidence interval, 0.379 to 0.997; p=0.048). Conclusion TRAP220 may be a valuable marker for nodal metastasis and TNM stage. Tumor co-expression of PPAR gamma and TRAP220 represents a biomarker for good prognosis in CRC patients.