Valproic acid activates notch-1 signaling and regulates the neuroendocrine phenotype in carcinoid cancer cells
Valproic acid activates notch-1 signaling and regulates the neuroendocrine phenotype in carcinoid cancer cells
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DOI：
10.1634/theoncologist.12-8-942
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发表时间：
2007-01-01
期刊：
影响因子：
5.8
通讯作者：
Chen, Herbert
中科院分区：
文献类型：
--
作者：
Greenblatt, David Yu;Vaccaro, Abram M.;Chen, Herbert
类癌是一种神经内分泌恶性肿瘤，它经常转移并分泌激素，导致患者出现衰弱症状。在这项研究中，我们报道了丙戊酸(VPA)，一种长期用于治疗癫痫的药物，对人类类癌癌细胞的生长和神经内分泌表型的影响。VPA处理胃肠道和肺类癌细胞后，癌细胞的生长受到剂量依赖性的抑制。Western印迹分析显示，VPA处理后细胞周期蛋白D1降解，细胞周期蛋白依赖性蛋白激酶p21和p27表达增加。流式细胞仪检测证实VPA抑制细胞生长的机制是使细胞周期停滞于G1期。此外，VPA抑制神经内分泌肿瘤标志物嗜铬粒蛋白A的表达。除了这些作用外，VPA还增加了全长Notch-1和活性Notch-1细胞内结构域的水平。荧光素酶报告基因结合着丝粒结合因子1(CBF-1)结合位点和ASCL-1启动子证实了VPA诱导的Notch-1的功能活性。将Notch-1小干扰RNA导入类癌细胞，可阻断VPA对Notch-1激活、ASCL-1抑制、p21诱导和细胞生长抑制的作用。在小鼠肿瘤异种移植实验中，VPA还抑制了体内类癌肿瘤的生长。这些发现证实了Notch-1在调节类癌细胞生长和神经内分泌表型中的重要作用。在这项研究的基础上，将进行VPA治疗晚期类癌患者的临床试验。
Carcinoid tumors are neuroendocrine malignancies that frequently metastasize and secrete hormones that cause debilitating symptoms in patients. In this study we report the effects of valproic acid (VPA), a drug long used for the treatment of epilepsy, on the growth and neuroendocrine phenotype of human carcinoid cancer cells. VPA treatment of gastrointestinal and pulmonary carcinoid cells resulted in a dose-dependent inhibition of cancer cell growth. Western blot analysis revealed degradation of cyclin D1 and an increase in cyclin-dependent kinases p21 and p27 with VPA treatment. Flow cytometry confirmed that the mechanism of VPA-induced growth inhibition is G1 phase cell cycle arrest. Furthermore, VPA suppressed expression of the neuroendocrine tumor marker chromogranin A. In addition to these effects, VPA also increased levels of full-length Notch-1 and the active Notch-1 intracellular domain. Luciferase reporter assays incorporating the centromere-binding factor 1 (CBF-1) binding site and the achaete-scute complex-like 1 (ASCL-1) promoter confirmed the functional activity of VPA-induced Notch-1. Transfection of Notch-1 small-interfering RNA into carcinoid tumor cells blocked the effects of VPA on Notch-1 activation, ASCL-1 suppression, p21 induction, and cell growth inhibition. VPA also suppressed growth of carcinoid tumors in vivo in a mouse tumor xenograft experiment. These findings confirm the important role of Notch-1 in regulating the growth and neuroendocrine phenotype of carcinoid tumor cells. On the basis of this study, a clinical trial of VPA for patients with advanced carcinoid cancer will be conducted.