Background and objective: Bufalin, a component of the Chinese medicine chan'su, induces apoptosis in various human tumor cell lines. The aim of this study is to investigate the mechanism of anti-proliferation and the induction of apoptosis of Bufalin on non-small cell lung cancer cell.
Methods: The effect of Bufalin on A549 cell proliferation was measured using MTT assay; the morphological change was observed with Wright-Giemsa stain; cell cycle phase distribution and hypodiploid DNA were determined by flow cytometry with PI; expressions of Livin, Caspase-3 were detected by Western blot.
Results: MTT assay showed that Bufalin inhibited A549 cell proliferation in time and dose-dependent manner. The inhibition concentration of 50% cell growth (IC50) at 48 h, 72 h and 96 h were (56.14+/-6.72) nmol/L, (15.57+/-4.28) nmol/L and (7.39+/-4.16) nmol/L, respectively; apoptosis of A549 cells could be effectively induced by Bufalin; apoptotic bodies and sub-G1 peak (representing apoptosis) emerged when cells were treated with different concentrations, compared with the untreated control group (P < 0.01). The expression of Livin protein was downregulated (P < 0.01) and Caspase-3 protein was activated during Bufalin-induced apoptosis in A549 cells.
Conclusions: Bufalin suppresses the growth of A549 cells and induces apoptosis; inhibition of Livin and activation of Caspase-3 may be involved in its mechanism.
背景与目的: 蟾蜍灵是从中药蟾酥中提取出来的有效成分，其抗肿瘤作用已经在许多体外肿瘤细胞中得到证实，本研究旨在探讨蟾蜍灵对人非小细胞肺癌细胞的增殖抑制、诱导凋亡作用及其机制。
方法: 采用MTT法测定细胞活力，绘制细胞增殖抑制曲线；瑞氏-吉姆萨染色法观察细胞形态学的变化；流式细胞仪通过PI染色进行细胞周期分析及凋亡判定；Western blot法检测Livin及Caspase-3蛋白的表达。
结果: 蟾蜍灵以时间、剂量依赖方式抑制A549细胞增殖，48 h、72 h及96 h抑制细胞增殖50%的药物浓度（half maximal inhibitory concentration, IC50）分别为（56.14±6.72）nmol/L、（15.57±4.28）nmol/L及（7.39±4.16）nmol/L；蟾蜍灵能诱导肺癌细胞凋亡，形态学表现为出现凋亡小体及流式细胞仪检测到的亚二倍体凋亡峰，凋亡率与对照组比较差异有统计学意义（均P < 0.01）；蟾蜍灵诱导细胞凋亡过程中，下调Livin蛋白表达（P < 0.01），同时活化Caspase-3蛋白。
结论: 蟾蜍灵能够抑制肺癌细胞A549的增殖，并诱导其凋亡；抑制凋亡抑制蛋白Livin的活性及活化Caspase-3可能在其抑癌机制中发挥重要作用。