Objective To investigate the impact of hypoxia inducible factor (HIF)-1α gene silencing on cell growth,invasion and apoptosis in human pancreatic cancer cell line (BxPC-3) under hypoxia condition.Methods The small interfering RNA (siRNA) was synthesized in order to silence the expression of HIF-1α in BxPC-3 cell line.The cells were divided into three groups:blank control group (BxPC-3),empty plasmid vector transfection group (GFP) and HIF-1α gene silencing group (sh-HIF-1α).All cells were cultured under either normal (21.0％ O2) or hypoxia (0.5％-1.0％ O2) condition for 48 h.Then the cell growth curve was plotted.The invasion ability and apoptosis among three groups were compared respectively.Results HIF-1α mRNA expression in BxPC-3 group and GFP group was upregulated by 78.4％ and 67.6％ (P ＜0.05) under hypoxic conditions,and HIF-1α protein level was increased correspondingly (7.1 folds and 6.2 folds respectively).However,HIF-1α expression in sh-HIF-1α group was dramatically reduced as compared with other two control groups (P ＜ 0.05).The cell growth rate in the sh-HIF-1α group was significantly slower than in BxPC-3 and GFP groups (P ＜ 0.05).The number of transmembrane cells in sh-HIF-1α group [(48.8 ± 3.8)/HP] was also less than in BxPC-3 group [(118.0 ± 6.8)/HP] and GFP group [(116.3 ± 6.4)/HP,P ＜ 0.01].On the contrary,the apoptosis rate induced by hypoxia in sh-HIF-1α group was (20.6 ± 1.3)％,which was 14.8 folds as great as that in normoxic conditions,and significantly higher than in BxPC-3 group [(2.3 ± 0.3) ％] and GFP group [(2.8 ± 0.9) ％] (P ＜ 0.01).Conclusion Hypoxia could induce the expression of HIF-1 α in BxPC-3 cells and increase the tolerant ability of cells to hypoxia stress.HIF-1α knockout would greatly inhibit the cell growth rate and the invasion ability of BxPC-3 cells,and the apoptosis rate induced by hypoxia was significantly enhanced.