Antitumor Effect of Angiotensin II Type 1 Receptor Blocker Losartan for Orthotopic Rat Pancreatic Adenocarcinoma

Objective: The aim of this study was to investigate the synergistic inhibitory effects of gemcitabine and losartan, angiotensin II type 1 (AT1) receptor blockers, on an orthotopic rat pancreatic cancer model. Methods: The rat orthotopic pancreatic cancer model was prepared using DSL-6A/C cells, a rat ductal pancreatic adenocarcinoma cell line. The rats were treated with gemcitabine alone (100 mg/kg per week), losartan alone (100 mg/kg per day), or gemcitabine plus losartan. Results: Survival was significantly improved by treatment with gemcitabine (89.6 +/- 21.8 days) or losartan (76.9 +/- 18.7 days) alone compared with that in the control group (59.6 +/- 13.4 days; P < 0.05). Treatment with gemcitabine plus losartan further prolonged the survival time to 102.6 +/- 16.5 days compared with that in the control group (P < 0.0001). Gemcitabine or losartan significantly and dose-dependently reduced the proliferation of DSL-6A/C cells in vitro. Both drugs inhibited pancreatic vascular endothelial growth factor expression compared with that in the control group (P < 0.05). Conclusions: The results of this study indicate that combined treatment with gemcitabine and losartan significantly improved the survival of rats with orthotopic pancreatic cancer by inhibiting vascular endothelial growth factor synthesis and suppressing cancer cell proliferation via AT1 receptor blockade. Thus, an AT1 receptor blocker in combination with gemcitabine might improve the clinical outcomes of patients with advanced pancreatic cancer.