中文摘要：

目的探讨IL-21对弥漫大B淋巴瘤（DLBCL）细胞系SUDHL4细胞凋亡的影响及其相关机制。方法用不同浓度IL-21（终浓度1、10、100、1000ng／m1）处理SUDHL4细胞不同时间（24、48、72h），用CCK-8试剂盒检测细胞增殖抑制率，绘制细胞增殖抑制曲线，计算IC50值；用流式细胞术检测细胞凋亡；用Westernblot法检测IL-21处理后SUDHL-d细胞caspase-9、caspase-3、cleavedcaspase-3、Bcl-2、Bcl-XL、Bid、Bax和c-myc蛋白表达。用RT-PCR法检测Bcl-2、Bcl-XL、Bid、Bax、c-myc和Sur-vivin基因mRNA表达。结果IL-21可明显抑制SUDHL4细胞增殖，且呈时间-剂量依赖性，其48h半数抑制浓度（IC50）为140．9ng／ml。流式细胞术分析发现100ng／mlIL-21处理的SUDHL-4细胞48h凋亡率（AnnexinV-FITC^＋细胞率）明显增加[（19．7±2．3）％]，同时caspase-9、caspase-3、Bcl-2和Bcl-XL蛋白表达减低，均呈时间依赖性。cleavedcaspase-3从48h开始出现明显的剪切带；Bax和c-myc蛋白表达明显增高，而Bid蛋白表达变化不明显。RT-PCR检测显示IL-21上调c-myc和Bax基因mRNA的表达，下调Bcl-2和Bcl-XL基因mRNA的表达，Bid和Survivin基因mRNA表达变化不明显。结论IL-21可抑制SUDHL-4细胞增殖，诱导细胞凋亡，其作用可能是通过c-myc和Bcl-2基因调节的线粒体途径实现。

英文摘要：

Objective To investigate the apoptosis effect of diffuse large B-cell lymphoma cell line （DLBCL） SUDHL-4 induced by IL-21 and its related mechanism. Methods SUDHL-4 cells were treated with IL-21 at different concentration （ 1,10,100,1000 ng/ml） for 24, 48,72 h, respectively. The inhibitory rate of cell proliferation was detected by CCK-8 assay. The cell growth curves were drawn and half inhibitory concentration （IC50） values were calculated. The cell apoptosis were detected by flow cytometry （FCM） , the expression of the caspase-9, caspase-3, cleaved caspase-3, Bcl-2, Bcl-XL, Bid, Bax and c-myc protein in SUDHL-4 cells treated with IL-21 by western blot, the mRNA expression of Bcl-2,Bcl-XL, Bid, Bax,c-myc by Survivin gene with RT-PCR. Results IL-21 markedly inhibited SUDHL-4 cell growth in a time- and dose- dependent manner. The 48 h IC5o was 140.9ng/ml;The FCM showed that the apoptosis proportion of SUDHL- 4 cells treated with 100 ng/ml of IL-21 apoptosis （Annexin V-FITC^＋ positive cells） gradually increased （48 h：19.7±2.3% ）. The protein expression of caspase-9, caspase-3, Bcl-2 and Bcl-XL decreased in a time-dependent manner. The Bax and c-myc protein markedly increased, but the Bid protein level did not change. IL-21 up regulated c-myc and Bax gene expression, however down regulated Bcl-2 and Bcl- XL gene expression, but the gene expression of Bid and Survivin hadn＇ t been changed significantly. Conclusions IL-21 can inhibit proliferation and induce apoptosis of SUDHL-4 cell. The mechanism may involve in endoge- nous mitochondrial pathway mediated by the c-myc and the Bcl-2 genes.