Gemcitabine has limited clinical benefits for pancreatic ductal
adenocarcinoma (PDAC). The phosphatidylinositol-3-kinase (PI3K)/AKT and
mammalian target of rapamycin (mTOR) signaling pathways are frequently dysregulated in PDAC. We investigated the effects of
NVP-BEZ235, a novel dual PI3K/mTOR inhibitor, in combination with
gemcitabine and
endothelial monocyte activating polypeptide II (EMAP) in experimental PDAC. Cell proliferation and
protein expression were analyzed by WST-1 assay and Western blotting. Animal survival experiments were performed in murine xenografts.
BEZ235 caused a decrease in phospho-AKT and phospho-mTOR expression in PDAC (AsPC-1), endothelial (HUVECs), and fibroblast (WI-38) cells.
BEZ235 inhibited in vitro proliferation of all four PDAC cell lines tested. Additive effects on proliferation inhibition were observed in the BEZ235-gemcitabine combination in PDAC cells and in combination of
BEZ235 or EMAP with
gemcitabine in HUVECs and WI-38 cells.
BEZ235, alone or in combination with
gemcitabine and EMAP, induced apoptosis in AsPC-1, HUVECs, and WI-38 cells as observed by increased expression of cleaved
poly (ADP-ribose) polymerase-1 (PARP-1) and
caspase-3 proteins. Compared to controls (median survival: 16 days), animal survival increased after
BEZ235 and EMAP
therapy alone (both 21 days) and
gemcitabine monotherapy (28 days). Further increases in survival occurred in combination
therapy groups
BEZ235 +
gemcitabine (30 days, P = 0.007),
BEZ235 + EMAP (27 days, P = 0.02),
gemcitabine + EMAP (31 days, P = 0.001), and
BEZ235 +
gemcitabine + EMAP (33 days, P = 0.004).
BEZ235 has experimental PDAC antitumor activity in vitro and in vivo that is further enhanced by combination of
gemcitabine and EMAP. These findings demonstrate advantages of combination
therapy strategies targeting multiple pathways in
pancreatic cancer treatment.