Purpose: Peroxisome proliferator-activated receptor gamma (PPARgamma) is a ligand-activated transcription factor that has been implicated in carcinogenesis and progression of various solid tumors, including pancreatic carcinoma. We aimed to clarify the expression patterns of PPARgamma in pancreatic ductal carcinomas and to correlate these to clinicopathologic variables, including patient survival.
Experimental design: Array-based expression profiling of 19 microdissected carcinomas and 14 normal ductal epithelia was conducted. Additionally, Western blots of pancreatic cancer cell lines and paraffinized tissue of 129 pancreatic carcinomas were immunostained for PPARgamma. For statistical analysis, Fisher's exact test, chi2 test for trends, correlation analysis, Kaplan-Meier analysis, and Cox's regression were applied.
Results: Expression profiles showed a strong overexpression of PPARgamma mRNA (change fold, 6.9; P=0.04). Immunohistochemically, PPARgamma expression was seen in 71.3% of pancreatic cancer cases. PPARgamma expression correlated positively to higher pT stages and higher tumor grade. Survival analysis showed a significant prognostic value for PPARgamma, which was found to be independent in the clinically important subgroup of node-negative tumors.
Conclusions: PPARgamma is commonly up-regulated in pancreatic ductal adenocarcinoma and might be a prognostic marker in this disease. Both findings corroborate the importance of PPARgamma in tumor progression of pancreatic cancer.