Department of Molecular Biology, College of Natural Science, Pusan National University, Busan 609-735, Korea.
Exp Mol Med. 2009 Sep 30;41(9):678-85. doi: 10.3858/emm.2009.41.9.074.
In spite of the importance of phospholipase D (PLD) in cell proliferation and tumorigenesis, little is known about the molecules regulating PLD expression. Thus, identification of small molecules inhibiting PLD expression would be an important advance for PLD- mediated physiology. We examined one such here, denoted Triptolide, which was identified in a chemical screen for inhibitors of PLD expression using cell assay system based on measurement of PLD promoter activity. Triptolide significantly suppressed the expression of both PLD1 and PLD2 with sub-mM potency in MDA-MB-231 breast cancer cells as analyzed by promoter assay and RT-PCR. Moreover, triptolide abolished the protein level of PLD in a time and dose-dependent manner. Triptolide-induced PLD1 downregulation was also observed in all the cancer cells examined, suggesting a general phenomenon detected in various cancer cells. Decrease of PLD expression by triptolide suppressed both basal and PMA-induced PLD activity. In addition, triptolide inhibited activation of NFkB which increased PLD1 expression. Ultimately, downregulation of PLD by triptolide inhibited proliferation of breast cancer cells. Taken together, we demonstrate that triptolide suppresses the expression of PLD via inhibition of NFkappaB activation and then decreases cell proliferation.
尽管磷脂酶 D（PLD）在细胞增殖和肿瘤发生中具有重要作用，但对于调节 PLD 表达的分子知之甚少。因此，鉴定抑制 PLD 表达的小分子将是 PLD 介导的生理学的重要进展。我们在这里研究了一种这样的小分子，称为雷公藤内酯，它是在使用基于 PLD 启动子活性测量的细胞测定系统筛选 PLD 表达抑制剂时发现的。雷公藤内酯在 MDA-MB-231 乳腺癌细胞中以亚毫摩尔效力显着抑制 PLD1 和 PLD2 的表达，如启动子测定和 RT-PCR 分析所示。此外，雷公藤内酯以时间和剂量依赖的方式消除 PLD 的蛋白水平。在所有检查的癌细胞中也观察到雷公藤内酯诱导的 PLD1 下调，这表明在各种癌细胞中检测到了一种普遍现象。雷公藤内酯降低 PLD 表达可抑制基础和 PMA 诱导的 PLD 活性。此外，雷公藤内酯抑制了增加 PLD1 表达的 NFkB 的激活。最终，雷公藤内酯下调 PLD 抑制了乳腺癌细胞的增殖。总之，我们证明雷公藤内酯通过抑制 NFkappaB 激活来抑制 PLD 的表达，从而降低细胞增殖。
