TRAIL-induced expression of uPA and IL-8 strongly enhanced by overexpression of TRAF2 and Bcl-xL in pancreatic ductal adenocarcinoma cells

BACKGROUND:The death ligand,tumor necrosis factor(TNF)related apoptosis-inducing ligand(TRAIL),induces apoptosis and non-apoptotic signaling in some tumor cells.The purpose of this study was to investigate the roles of the pro-apoptotic TRAIL receptors,TRAIL-R1 and TRAIL-R2,as well as Bcl-xL and TRAF2 in TRAIL-induced expression of the pro-inflammatory cytokine IL-8 and the invasion-promoting protein urokinase(uPA) in pancreatic ductal adenocarcinoma(PDAC) cells.METHODS:Colo357wt,Colo357/TRAF2,Colo357/Bcl-xL,Panc89 and PancTuI cells were stimulated with TRAIL and uPA and IL-8 expression was detected using real-time PCR.Antagonistic,receptor-specific antibodies were used to investigate the effects of TRAIL-R1 or TRAIL-R2 inhibition.RESULTS:Dose-dependent increases in uPA and IL-8 expression were detected following TRAIL stimulation in PDAC cells.These effects were inhibited when TRAIL-R1 but not TRAIL-R2 was blocked.Overexpression of TRAF2 or Bcl-xL strongly increased TRAIL-mediated upregulation of uPA and IL-8.CONCLUSIONS:In PDAC cells,TRAIL strongly induced uPA and IL-8 via TRAIL-R1.This response was further enhanced in cells overexpressing TRAF2 and Bcl-xL.Therefore,inhibition of the non-apoptotic "side-effects" of TRAIL treatments by inactivation of TRAF2 and Bcl-xL might represent additional relevant strategies for the treatment of pancreatic cancer.