Peroxisome proliferator-activated receptor-gamma and retinoid X receptor-alpha expression in pancreatic ductal adenocarcinoma: association with clinicopathological parameters, tumor proliferative capacity, and patients' survival
Constantinos Giaginis, Eleftheria Katsamangou, Gerasimos Tsourouflis, Diamanto Zizi-Serbetzoglou, Gregorios Kouraklis, Stamatios Theocharis
Med Sci Monit 2009; 15(5): BR148-156
Available online: 2009-04-23
Peroxisome proliferator-activated receptor-gamma (PPAR-gamma), a ligand-activated transcription factor that forms heterodimers with the retinoid X receptors (RXRs), is overexpressed in various tumors, regulating many aspects of cancer biology. The aim of the present study was to evaluate the clinical significance of PPAR-gamma and RXR-alpha expression in pancreatic adenocarcinoma.
Material and Method: PPAR-gamma and RXR-alpha protein expression was assessed immunohistochemically in tumoral samples of 65 pancreatic adenocarcinoma patients and statistically analyzed in relation to clinicopathological characteristics, tumor proliferative capacity, and patients' survival.
Results: Of the 65 adenocarcinoma patients, 49 (75%) tested positive for PPAR-gamma and 55 (85%) stained positive for RXR-alpha. RXR-alpha positivity was significantly associated with tumor proliferative capacity and PPAR-gamma positivity (p=0.022 and p=0.043, respectively). PPAR-gamma and RXR-alpha staining intensity were associated with the histopathological tumor grade (p=0.003 and p=0.038, respectively). Significant associations of PPAR-gamma staining intensity and RXR-alpha expression with tumor size were also noted (p=0.041 and p=0.038, respectively). Moderate and intense PPAR-gamma staining intensity was associated with shorter overall survival in univariate analysis (log-rank test, p=0.023) and proved to be an independent prognostic factor in multivariate analysis (p=0.045), whereas RXR-alpha failed to predict patients' survival.
Conclusions: These data revealed that both PPAR-gamma and RXR-alpha were associated with pancreatic cancer characteristics. PPAR-gamma, but not RXR-alpha, was found to be an independent prognostic indicator. However, further molecular and clinical studies are required to delineate the potential clinical application of PPAR-gamma and RXR-alpha in the prognosis and management of pancreatic adenocarcinoma patients.
Keywords: Retinoid X Receptors - metabolism, Pancreatic Neoplasms - pathology, PPAR gamma - metabolism, Cell Proliferation, Carcinoma, Pancreatic Ductal - pathology, Adenocarcinoma - pathology, Survival Analysis