Pancreatitis is associated with release of proinflammatory
cytokines and
reactive oxygen species and plays an important role in the development of
pancreatic cancer. We recently demonstrated that
dual oxidase (Duox)2, an
NADPH oxidase essential for
reactive oxygen species-related, gastrointestinal host defense, is regulated by IFN-γ-mediated Stat1 binding to the
Duox2 promoter in pancreatic
tumor lines. Because LPS enhances the development and invasiveness of
pancreatic cancer in vivo following TLR4-related activation of NF-κB, we examined whether LPS, alone or combined with IFN-γ, regulated
Duox2. We found that upregulation of TLR4 by IFN-γ in BxPC-3 and CFPAC-1
pancreatic cancer cells was augmented by LPS, resulting in activation of NF-κB, accumulation of NF-κB (p65) in the nucleus, and increased binding of p65 to the
Duox2 promoter. TLR4 silencing with small interfering RNAs, as well as two independent NF-κB inhibitors, attenuated LPS- and IFN-γ-mediated
Duox2 upregulation in BxPC-3 cells. Induction of
Duox2 expression by IFN-γ and LPS may result from IFN-γ-related activation of Stat1 acting in concert with NF-κB-related upregulation of
Duox2. Sustained extracellular accumulation of H(2)O(2) generated by exposure to both LPS and IFN-γ was responsible for an ∼50% decrease in BxPC-3 cell proliferation associated with a G(1) cell cycle block, apoptosis, and DNA damage. We also demonstrated upregulation of Duox expression in vivo in
pancreatic cancer xenografts and in patients with
chronic pancreatitis. These results suggest that inflammatory
cytokines can interact to produce a Duox-dependent
pro-oxidant milieu that could increase the pathologic potential of pancreatic
inflammation and
pancreatic cancer cells.