Prognostic significance and therapeutic implications of peroxisome proliferator-activated receptor γ overexpression in human pancreatic carcinoma.

Peroxisome proliferator-activated receptor γ (PPARγ) is a ligand-activated nuclear receptor which has been implicated in carcinogenesis and angiogenesis in a wide range of cancers, including pancreatic carcinoma (PC). We aimed to characterize the prognosis and potential therapeutic implications of PPARγ in PC. Real-time RT-PCR and western blotting were used to quantify PPARγ expression in immortalized pancreatic epithelial cells, PC cell lines and freshly isolated matched tumor and non-tumor tissues. PPARγ protein expression was analyzed by immunohistochemistry (IHC) in archived tumor tissues from 101 PC patients. Furthermore, the effect of PPARγ on the cytotoxic action of gemcitabine (Gem) and 5-fluorouracil (5-FU) in PC cell lines was investigated in vitro using RNA interference techniques. Both PPARγ protein and mRNA were expressed at markedly higher levels in all of the PC cell lines and freshly isolated PC tissues, compared to normal immortalized pancreatic epithelial cells and the matched adjacent non-tumor tissues. High levels of PPARγ expression correlated significantly with tumor-node-metastasis (TNM) staging (P<0.001) and poor overall survival (P<0.001), especially in patients with advanced disease who received postoperative chemotherapy. While silencing of PPARγ significantly inhibit the cytotoxic effects of both gemcitabine and 5-fluorouracil in PC cells in vitro. This study suggests that high levels of PPARγ expression are associated with poor overall survival in PC. Additionally, PPARγ promotes chemoresistance in PC cells, indicating that PPARγ may represent a novel therapeutic target for PC.