OBJECTIVETo investigate the effect of down-regulation of Notch1 by Notch1 small interfering RNA (siRNA) on chemosensitivity to gemcitabine in pancreatic cancer cells and its mechanism.

METHODSNotch1 siRNA was transfected to pancreatic cancer cell lines AsPC-1, BxPC-3, MIAPaCa-2 and Panc-1. The transfected pancreatic cancer cells were treated with 10 μmol/L gemcitabine in vitro. The relative quantity of Notch1 mRNA of pancreatic cancer cells was detected by real-time PCR. The inhibition rates of gemcitabine-treated cells were evaluated by CCK-8 method. The expression of Bax protein was examined by Western blot, and the caspase 3 activity was detected by CaspACETM assay system kit.

RESULTSThe relative quantity of Notch1 mRNA was the highest in BxPC-3 cell line and the lowest in Panc-1 cells. The inhibition rates of gemcitabine treated-cells were significantly higher in Notch1 siRNA transfection groups than in corresponding siRNA control groups (AsPC-1: 67.5±6.7 vs 47.5±6.8; BxPC-3: 90.5±4.4 vs 70.2±4.2; MIAPaCa-2: 80.9±5.7 vs 58.1±6.0; Ps<0.05), with the overexpression of protein Bax. The activity of caspase 3 was also significantly increased in Notch1 siRNA transfection groups compared with corresponding siRNA control groups (AsPC-1: 28.90±2.70 vs 12.82±3.44; BxPC-3: 59.87±6.77 vs 27.27±11.88; MIAPaCa-2: 29.34±4.06 vs 14.59±4.25; P<0.05).

CONCLUSIONInhibition of Notch signaling pathway by Notch1 siRNA can enhance chemosensitivity to gemcitabine in pancreatic cancer cells through activating apoptosis activity．