Antiprotease strategy in pancreatic cancer treatment: emergence from a preclinical study.

OBJECTIVES: Resistance to gemcitabine is one of the main causes of treatment failure in pancreatic cancer. Compelling evidences have shown the involvement of nuclear factor κB (NF-κB) activation in such phenomenon. The protease inhibitor gabexate mesilate has been shown to inhibit NF-κB. We here investigated if combined treatment with this drug could improve gemcitabine antitumoral efficacy in pancreatic cancer cells. METHODS: The effect of gabexate mesilate and gemcitabine, both used at concentrations achievable in human plasma, was assessed on in vitro pancreatic cancer cell growth, invasion, and tumor angiogenesis. The molecular mechanism at the basis of these effects was also investigated. RESULTS: Gabexate mesilate significantly increased gemcitabine anti-invasive and antiangiogenic efficacy. This effect was related to inhibition of gemcitabine-induced NF-κB activation by gabexate mesilate, which prevented RelA/p65 nuclear translocation and resulted in metalloproteinase 2, metalloproteinase 9, vascular endothelial growth factor, and interleukin 8 down-regulation. Combined treatment with gabexate mesilate also inhibited gemcitabine-induced extracellular-regulated kinase 1/2 and AKT activation by increased expression of Raf kinase inhibitor protein and phosphatase and tensin homolog. CONCLUSIONS: Combined treatment with gabexate mesilate sensitizes pancreatic cancer cells to gemcitabine by inhibition of the NF-κB pathway. The efficacy of this therapeutic strategy in pancreatic cancer patients remains to be established and deserves future clinical investigation.