Function of nuclear factor kappaB in pancreatic cancer metastasis

We seek to elucidate the role of constitutive nuclear factor kappaB (NFkappaB) activity in human pancreatic cancer cells. We have demonstrated that the transcription factor NFkappaB is activated constitutively in human pancreatic adenocarcinoma and human pancreatic cancer cell lines but not in normal pancreatic tissues or in immortalized/nontumorigenic pancreatic epithelial cells, suggesting that NFkappaB plays a critical role in development of pancreatic adenocarcinoma.

By pooling all of the puromycin resistant clones after inhibitor of nuclear factor-kappaB phosphorylation mutant (IkappaBalphaM) retroviral infection, we generated pancreatic tumor cell lines that express a IkappaBalphaM (S32, 36A) that blocks NFkappaB activity. Inhibition of metastatic phenotype was assayed in an orthotopic nude mouse model. NFkappaB activity was determined by electrophoretic mobility shift assay, and the expression of NFkappaB downstream target genes was analyzed by Northern, Western, and immunohistochemical analyses.

We showed that inhibiting constitutive NFkappaB activity by expressing IkappaBalphaM suppresses liver metastasis, but not tumorigenesis, from the metastatic human pancreatic tumor cell line AsPc-1 in an orthotopic nude mouse model. Furthermore, inhibiting NFkappaB activation by expressing IkappaBalphaM significantly reduced in vivo expression of a major proangiogenic molecule, vascular endothelial growth factor, and, hence, decreased neoplastic angiogenesis. Inhibiting NFkappaB activation by expressing IkappaBalphaM and using pharmacologic NFkappaB inhibitor PS-341 also significantly reduced cytokine-induced vascular endothelial growth factor and interleukin-8 expression in AsPc-1 pancreatic cancer cells.

These results demonstrated that the inhibition of NFkappaB signaling can suppress the angiogenic potential and metastasis of pancreatic cancer, and suggest that the NFkappaB signaling pathway is a potential target for anticancer agents.