Nuclear factor-kappaB p65/relA silencing induces apoptosis and increases gemcitabine effectiveness in a subset of pancreatic cancer cells.

PURPOSE

Nuclear factor kappaB (NFkappaB) activity may increase survival and protect cancer cells from chemotherapy. Therefore, NFkappaB activity may be prognostic, and inhibition of NFkappaB may be useful for pancreatic cancer therapy. To test these hypotheses, we examined NFkappaB activity and the effects of inhibiting NFkappaB in several pancreatic cancer cell lines with differing sensitivities to gemcitabine.

EXPERIMENTAL DESIGN

The gemcitabine sensitivity of pancreatic cancer cell lines BxPC-3, L3.6pl, CFPAC-1, MPanc-96, PANC-1, and MIA PaCa-2 were determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide and fluorescence-activated cell sorting assays. NFkappaB levels were determined by electrophoretic mobility shift assay and reporter assays. The effects of gemcitabine on NFkappaB activity were determined in vitro and in vivo. NFkappaB was inhibited by silencing of the p65/relA subunit using small interfering RNA in vitro and by neutral liposomal delivery of small interfering RNA in vivo, and the effects were evaluated on gemcitabine sensitivity.

RESULTS

The cell lines L3.6pl, BxPC-3, and CFPAC-1 were sensitive, whereas MPanc-96, PANC-1, and MIA PaCa-2 were resistant to gemcitabine. No significant correlation was observed between basal NFkappaB activity and gemcitabine sensitivity. Gemcitabine treatment did not activate NFkappaB either in vitro or in vivo. Silencing of p65/relA induced apoptosis and increased gemcitabine killing of all gemcitabine-sensitive pancreatic cancer cells. No significant effects, however, were observed on gemcitabine-resistant pancreatic cancer cell lines either in vitro or in vivo.

CONCLUSIONS

NFkappaB activity did not correlate with sensitivity to gemcitabine. Silencing of p65/relA was effective alone and in combination with gemcitabine in gemcitabine-sensitive but not gemcitabine-resistant pancreatic cancer cells. Thus, NFkappaB may be a useful therapeutic target for a subset of pancreatic cancers.