Objective To investigate the effects of E2F-1 gene silencing on the chemosensitivity of human gastric cancer SGC-7901/DDP cells to cisplatin and explore the underlying mechanism. Methods Gastric cancer SGC-7901/DDP cells were transfected with the recombinant lentivirirus vector Lv-shRNA-E2F-1 for E2F-1 gene silencing, with cells transfected with the control recombinant lentivirirus vector Lv- shRNA- NC as the negative control. MTT assay was used to evaluate cisplatinchemosensitivity of the cells, and the cell apoptosis rate and cell cycle distribution were detected by flow cytometry. The mRNA and protein expressions of E2F-1 and apoptosis-related genes (survivin and Bcl-2) were detected by RT-PCR and Western blotting. Results MTT assay showed that the IC50 of cisplatinwas significantly lowered in Lv-shRNA-E2F-1-transfected cells compared with the negative and blank control cells (P<0.05). Lv-shRNA-E2F-1 transfection caused significant cell cycle arrest in G0/G1 phase and induced obvious cell apoptosis. Compared with Lv-shRNA-NC group and the blank control group, Lv-shRNA-E2F-1 group showed significantly lowered expressions of E2F-1 mRNA by 45.0%and 41.3%and E2F-1 protein by 66.7%and 70.5%, survivin mRNA by 30.3%and 28.7%and survivin protein by 56.5%and 53.6%, and Bcl-2 mRNA by 76.6%and 76.8% and Bcl-2 protein by 74.6% and 79.9%, respectively. No significant difference was found in the measurements between Lv-shRNA-NC group and the blank control group (P>0.05). Conclusion E2F-1 gene silencing can enhance cisplatinchemosensitivity of gastric cancer SGC-7901/DDP cells possibly by down-regulating survivin and Bcl-2 expressions, suggesting the value of E2F-1 as a new chemotherapeutic target for gastric cancer.%目的：探讨E2F转录因子1（E2F transcription factor 1, E2F-1）基因沉默对人胃癌耐药细胞株SGC-7901/DDP对顺铂敏感性的影响及可能机制。方法将SGC-7901/DDP细胞接种于六孔板，分为3组：以E2F-1沉默重组慢病毒颗粒（Lv-shRNA-E2F-1）感染SGC-7901/DDP，作为Lv-shRNA-E2F-1组；以阴性对照慢病毒颗粒（Lv-shRNA-NC）感染SGC-7901/DDP，作为Lv-shRNA-NC组；空白对照组不做任何处理。以MTT法测定转染后各组细胞对DDP的半数抑制浓度（IC50），并以AxnnexinV-PE/7-AAD双染色流式细胞术检测各组细胞凋亡率及周期分布。应用Western blot和半定量RT-PCR技术分别对各组细胞中E2F-1、survivin、Bcl-2的mRNA及蛋白水平进行检测。结果与Lv-shRNA-NC组和空白对照组相比，Lv-shRNA-E2F-1组细胞对顺铂的IC50显著降低，细胞凋亡率显著提高，细胞周期阻滞于G0/G1期，差别均有统计学意义（P<0.05）；Lv-shRNA-E2F-1组E2F-1 mRNA水平较Lv-shRNA-NC组和空白对照组分别下降45.0%和41.3%，蛋白水平分别下降66.7%和70.5%（均P<0.01）；Lv-shRNA-E2F-1组survivin mRNA水平较Lv-shRNA-NC组和空白对照组分别下降30.3%和28.7%，蛋白水平分别下降56.5%和53.6%（均P<0.01）；Lv-shRNA-E2F-1组Bcl-2 mRNA水平较Lv-shRNA-NC组和空白对照组分别下降76.6%和76.8%，蛋白水平分别下降74.6%和79.9%（均P<0.01）；Lv-shRNA-NC组与空白对照组比较，上述指标差别均无统计学意义（均P>0.05）。结论：沉默E2F-1基因可有效提高人胃癌耐药细胞株SGC-7901/DDP对顺铂的敏感性，其机制可能与survivin及Bcl-2表达下调有关，提示E2F-1可能成为胃癌药物治疗的新靶点。
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