水飞蓟素在紫外线照射诱导A375-S2细胞凋亡中发挥抑制作用

目的：从天然药物中筛选出抑制紫外线照射诱导人黑色素瘤细胞A375-S2凋亡的有效单体。 方法： MTT法测定细胞生长抑制率；形态学观察，DNA凝胶电泳及LDH法；用半胱天冬酶活力检测试剂盒测定半胱天冬酶活力；用免疫印记法检测Bcl-2家族成员(Bcl-2, Bcl-xL和Bax)的表达。 结果： 紫外线照射(2.4 J/cm2, 5 min) 能显著诱导A375-S2细胞发生凋亡，其作用呈明显时间依赖性。形态学观察可见凋亡小体的形成，琼脂糖凝胶电泳可见凋亡典型的DNA梯带；水飞蓟素具有抑制紫外线照射 (2.4 J/cm2, 5 min) 诱导A375-S2细胞凋亡的作用，水飞蓟素作用于紫外线照射 (2.4 J/cm2, 5 min)的A375-S2细胞，培养12 h，使紫外线照射诱导的半胱天冬酶-9、半胱天冬酶-3的活力降低；免疫印记法检测发现水飞蓟素作用的A375-S2细胞 (紫外线照射) 中Bcl-2 蛋白和Bcl-xL蛋白的表达增加。 结论： 水飞蓟素明显抑制紫外线照射诱导的A375-S2细胞的凋亡，其抑制凋亡作用与半胱天冬酶途径和线粒体途径相关。

Preventive effect of silymarin on UV irradiation-induced A375-S2 cell apoptosis

AIM: To search for the active compound from Chinese herbal medicine which could inhibit ultraviolet (UV) irradiation-induced apoptosis in human malignant cells (A375-S2 cell). METHODS: MTT, photomicroscopical observation, DNA agarose gel electrophoresis, LDH release and Western blot analysis were used. Caspase activation was detected by using caspase apoptosis detection kit. RESULTS: Treatment with silymarin (500 μmol/L) for 12 h significantly inhibited UV irradiation (2.4 J/cm2, 5 min)-induced apoptosis in A375-S2 cells. Activities of caspase-9 and caspase-3 in UV-irradiated A375-S2 cells were effectively reduced by silymarin in a dose-dependent manner, while protein expressions of Bcl-2 and Bcl-xL (Bcl-2 family member) were increased simultaneously. CONCLUSION: Silymarin prevents UV irradiation-induced A375-S2 cell apoptosis through blockage of caspase pathway after protein expression of Bcl-2 and Bcl-xL.