Department of Pharmacology and Department of Biochemistry and Molecular Biology, Faculty of Medicine, Dalhousie University, Halifax, NS, CA.
Cancer Biol Ther. 2009 Nov;8(21):2054-62. doi: 10.4161/cbt.8.21.9803. Epub 2009 Nov 14.
Triptolide, a diterpene triepoxide derived from Trypterygium wilfordii, is documented to have antitumor activity in a broad range of solid tumors and leukemia. The mechanisms that are involved in triptolide-mediated apoptosis or growth inhibition in cancer cells are not fully understood. We identified a disintegrin and metalloproteinase 10 (ADAM10) as a novel molecular target of triptolide using affinity chromatography and mass spectrometry. The identification was confirmed by western blot analysis using an anti-ADAM10 antibody. The expression of ADAM10 is enhanced in several tumors including leukemia and is involved in malignant cell growth and cancer progression. ADAM10 is a type 1 transmembrane glycoprotein that cleaves several plasma membrane proteins. We show that triptolide, at concentrations in the nM range, resulted in a significant decrease in ADAM10 expression followed by the appearance of ADAM10 cleaved product. Furthermore, triptolide reduced the viability of monocytic leukemic U937 cells. Triptolide treatment of MCF-7 breast cancer cells expressing ectopic ADAM10 or dominant negative ADAM10 (DN ADAM10) resulted in a decreased expression of ADAM10 with a concomitant increase in ADAM10 cleaved products. Moreover, siRNA-mediated knockdown of ADAM10 mRNA significantly affected the growth of MCF-7 cells. Interestingly, the combination of siRNA-mediated knockdown of ADAM10 mRNA expression and triptolide treatment lead to a further reduction in cell growth. Taken together, we provide evidence that ADAM10 is a novel target of triptolide, presenting a novel strategy to inhibit ADAM10 activity in tumorigenesis.
雷公藤红素是从雷公藤中提取的二萜三环氧化合物，已被证实具有广泛的实体瘤和白血病的抗肿瘤活性。雷公藤红素介导的癌细胞凋亡或生长抑制的机制尚未完全阐明。我们使用亲和层析和质谱法鉴定了去整合素金属蛋白酶 10（ADAM10）是雷公藤红素的一个新的分子靶点。使用抗 ADAM10 抗体的 Western blot 分析证实了这一鉴定。ADAM10 的表达在包括白血病在内的几种肿瘤中增强，并且涉及恶性细胞生长和癌症进展。ADAM10 是一种 1 型跨膜糖蛋白，可切割几种质膜蛋白。我们表明，雷公藤红素在纳摩尔浓度范围内导致 ADAM10 表达显著下降，随后出现 ADAM10 切割产物。此外，雷公藤红素降低单核白血病 U937 细胞的活力。雷公藤红素处理表达异位 ADAM10 或显性负 ADAM10（DN ADAM10）的 MCF-7 乳腺癌细胞导致 ADAM10 表达减少，同时 ADAM10 切割产物增加。此外，siRNA 介导的 ADAM10 mRNA 敲低显著影响 MCF-7 细胞的生长。有趣的是，siRNA 介导的 ADAM10 mRNA 表达敲低和雷公藤红素处理的组合导致细胞生长进一步减少。总之，我们提供了证据表明 ADAM10 是雷公藤红素的一个新靶点，为抑制肿瘤发生中的 ADAM10 活性提供了一种新策略。
