Objective To investigate the effect of PDTC (inhibitor of NF-κb) on apoptosis of human gastric cancer cell line SGC-7901 induced by tumor necrosis factor α (TNF-α) and explore the related mechanisms.Methods After the treatment with different concentrations of PDTC,TNF-α or PDTC combined with TNF-α on gastric cancer cell line SGC-7901,the growth inhibition of SGC-7901 was measured by MTT assay.Hoechst was used to assess SGC-7901 cell apoptosis.The protein expressions of survivin and caspase-3 were detected by Western blot assay.Results The growth inhibition rate of SGC-7901 induced by PDTC (15,30,60,100 μmol/L) was (12.14Π0.91)％,(20.00±1.11)％,(37.63±1.01)％ and (41.46±1.07)％.Different concentrations of PDTC all inhibited the growth of SGC-7901 significantly (all P＜0.01),The growth inhibition rate of SGC-7901 induced by 25 mg/L TNF-α was (2.38±0.67)％,which could not significantly inhibit the growth of SGC-7901 [control (1.50±0.81)％],while TNF-α of 50,100,150 mg/L could inhibit the growth of SGC-7901 significantly [(4.53±0.85)％,(4.43±0.70)％ and(4.74±1.07)％,all P＜0.05].PDTC (15 μmol/L) combined with TNF-α (25,50,100,150 mg/L) significantly increased the cell growth inhibition rate compared with TNF-α alone or PDTC 15 μmol/L alone (all P＜0.01).Hoechst assay showed that 100 mg/L TNF-α,15 μmol/L PDTC and combination of above two all induced cell apoptosis (P＜0.01),and the combination group had significantly higher percentage of cell apoptosis(P＜0.01).Survivin protein was significantly down-regulated in combination group as compared with single TNF-α (100 mg/L) group,but was not significant down-regulated as compared with single PDTC (15 μmol/L) group.Caspase-3 protein expression was significantly increased in combination group as compared with other two groups.Conclusion PDTC can enhance the cell apoptosis induced by TNF-α,which may be associated with the blocking of TNF-α-activated NF-κB signaling pathway by PDTC,the down-regulation of survivin expression,and up-regulation of caspase-3 expression.%目的 研究核转录因子-κb(NF-κb)抑制剂吡咯烷二硫代氨基甲酸盐(PDTC)对肿瘤坏死因子α(TNF-α)诱导的人胃癌细胞株SGC-7901生长抑制及凋亡的影响,并探讨其作用机制.方法 应用噻唑蓝(MTT)法检测不同浓度的PDTC和TNF-α以及两者联合应用对SGC-7901细胞增殖的抑制率；采用Hoechst检测SGC-7901细胞凋亡情况；Western blot检测SGC-7901细胞survivin和caspase-3蛋白的表达.结果 PDTC在15、30、60和100 μmol/L浓度时,对SGC-7901的细胞生长抑制率分别为(12.14±0.91)％、(20.00±1.11)％、(37.63±1.01)％和(41.46±1.07)％,均可抑制细胞增殖(P＜0.01).TNF-α为25 mg/L时,对SGC-7901细胞的生长抑制率为(2.38±0.67)％,与对照组(1.50±0.81)％相比,差异无统计学意义(F=28.28,P＞0.05)；而在50、100和150 mg/L浓度时,对SGC-7901细胞的生长抑制率分别为(4.53±0.85)％、(4.43±0.70)％和(4.74±1.07)％,与对照组相比,差异有统计学意义(P＜0.05).PDTC 15 μmol/L分别与25、50、100和150 mg/L的TNF-α联合应用时,对SGC-7901的细胞生长抑制率则分别为(18.94±1.10)％、(30.23±0.89)％、(41.55±0.94)％和(53.34±0.98)％,与单用TNF-α或单用15 μmol/L PDTC比较,细胞生长抑制率增加(P＜0.01).Hoechst检测结果显示,TNF-α 100 mg/L组、PDTC 15 μmol/L组及两者联合应用组细胞凋亡率均显著增加(P＜0.01),且联合用药组细胞凋亡率增高最为显著(P＜0.01).PDTC(15μmol/L)与TNF-α(100 mg/L)联合用药与单用TNF-α(100 mg/L)比较,细胞survivin蛋白表达明显降低(P＜0.01),与单用PDTC(15 μmol/L)比较,差异无统计学意义(P＞0.05)；但caspase-3蛋白的表达联合用药组较两者分别单用时显著增加(P＜0.01).结论 PDTC可增强TNF-α对人SGC-7901细胞的促凋亡作用,其机制可能与PDTC阻断TNF-α诱导的NF-κb活性、下调survivin表达并最终上调凋亡蛋白caspase-3的表达有关.
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