Deshpande Vaidehee S, Kehrer James P
Division of Pharmacology and Toxicology, College of Pharmacy, The University of Texas at Austin, 1 University Station, A1915, Austin, TX 78712, USA.
Toxicol Appl Pharmacol. 2006 Aug 1;214(3):230-6. doi: 10.1016/j.taap.2005.12.011. Epub 2006 Feb 10.
Nordihydroguaiaretic acid (NDGA), a general lipoxygenase (LOX) enzyme inhibitor, induces apoptosis independently of its activity as a LOX inhibitor in murine pro-B lymphocytes (FL.12 cells) by a mechanism that is still not fully understood. Glutathione depletion, oxidative processes and mitochondrial depolarization appear to contribute to the apoptosis induced by NDGA. The current data demonstrate that NDGA (20 microM)-induced apoptosis in FL5.12 cells is partially protected by N-acetylcysteine (NAC) (10 mM) and dithiothreitol (DTT) (500 microM) pretreatment, confirming a role for oxidative processes. In addition, the treatment of FL5.12 cells with NDGA led to an increase in phosphorylation and activation of the MAP kinases ERK, JNK and p38. Although pretreatment with ERK inhibitors (PD98059 or U0126) abolished ERK phosphorylation in response to NDGA, neither inhibitor had any effect on NDGA-induced apoptosis. SP600125, a JNK inhibitor, did not have any effect on NDGA-induced phosphorylation of JNK nor apoptosis. Pretreatment with the p38 inhibitor SB202190 attenuated NDGA-induced apoptosis by 30% and also abolished p38 phosphorylation, compared to NDGA treatment alone. NAC, but not DTT, also decreased the phosphorylation of p38 and JNK supporting a role for oxidative processes in activating these kinases. Neither NAC nor DTT blocked the phosphorylation of ERK suggesting that this activation is not related to oxidative stress. The release of cytochrome c and activation of caspase-3 induced by NDGA were inhibited by NAC. SB202190 slightly attenuated caspase-3 activation and had no effect on the release of cytochrome c. These data suggest that several independent mechanisms, including oxidative reactions, activation of p38 kinase and cytochrome c release contribute to NDGA-induced apoptosis.
去甲二氢愈创木酸（NDGA）是一种通用的脂氧合酶（LOX）抑制剂，它在小鼠前B淋巴细胞（FL.12细胞）中通过一种尚未完全了解的机制诱导细胞凋亡，这种诱导作用与其作为LOX抑制剂的活性无关。谷胱甘肽耗竭、氧化过程和线粒体去极化似乎都与NDGA诱导的细胞凋亡有关。目前的数据表明，用N - 乙酰半胱氨酸（NAC）（10 mM）和二硫苏糖醇（DTT）（500 microM）预处理可部分保护FL5.12细胞免受NDGA（20 microM）诱导的细胞凋亡，这证实了氧化过程在其中的作用。此外，用NDGA处理FL5.12细胞导致丝裂原活化蛋白激酶ERK、JNK和p38的磷酸化和活化增加。尽管用ERK抑制剂（PD98059或U0126）预处理可消除NDGA诱导的ERK磷酸化，但两种抑制剂对NDGA诱导的细胞凋亡均无影响。JNK抑制剂SP600125对NDGA诱导的JNK磷酸化和细胞凋亡均无影响。与单独用NDGA处理相比，用p38抑制剂SB202190预处理可使NDGA诱导的细胞凋亡减少30%，并消除p38磷酸化。NAC而非DTT也可降低p38和JNK的磷酸化，这支持了氧化过程在激活这些激酶中的作用。NAC和DTT均未阻断ERK的磷酸化，表明这种活化与氧化应激无关。NAC抑制了NDGA诱导的细胞色素c释放和caspase - 3活化。SB202190略微减弱了caspase - 3活化，对细胞色素c释放无影响。这些数据表明，包括氧化反应、p38激酶活化和细胞色素c释放在内的几种独立机制都与NDGA诱导的细胞凋亡有关。
