Kunnimalaiyaan Muthusamy, Ndiaye Mary, Chen Herbert
Endocrine Surgery Research Laboratories, Section of Endocrine Surgery, Department of Surgery, Madison, Wisconsin, USA.
Surgery. 2007 Dec;142(6):959-64; discussion 959-64. doi: 10.1016/j.surg.2007.09.020.
We have shown previously that activation of the Raf-1/mitogen-activated protein kinase (MEK)/extracellular signal-regulated kinase (ERK)1/2 signaling pathway by ZM336372 inhibits carcinoid cells growth. In the present study, we further characterize the molecular details of the growth inhibition by the signaling-based compound ZM336372 in neuroendocrine neoplasms (NENs).
NEN cells were treated with ZM336372 (20 to 100 mumol/L) or carrier (DMSO). Western Blot was used to determine the activation of the Raf-1/MEK/ERK, other pathways activation, and cellular bioactive hormone production.
ZM336372 in NEN cells resulted in increasing raf-1 activation and inactivation of glycogen synthase kinase-3 beta (GSK-3beta) as measured by phosphorylation of ERK1/2 and GSK-3beta, respectively. There was no alteration in the levels of phosphorylated Akt, an important mediator of the phosphatidyl inositol 3 kinase pathway. Importantly, blocking of raf-1 pathway by U0126, a potent inhibitor, in the presence of ZM336372 did not reduce the levels of p-GSK-3beta, indicating that GSK-3beta inactivation is independent of raf-1 pathway activation. Moreover, the levels of chromogranin A and achaete-scute complex like-1 reductions were persistent even after blocking the raf-1 pathway. Treatment with ZM336372 in the presence of small interfering RNA against raf-1 resulted in an increase in Raf-1 production, suggesting that ZM336372 upregulates raf-1 at the transcriptional level.
This is the first description of a novel compound ZM336372 that regulates multiple pathways in NEN cells.
我们之前已经表明，ZM336372激活Raf-1/丝裂原活化蛋白激酶（MEK）/细胞外信号调节激酶（ERK）1/2信号通路可抑制类癌细胞生长。在本研究中，我们进一步阐述基于信号传导的化合物ZM336372在神经内分泌肿瘤（NENs）中抑制生长的分子细节。
用ZM336372（20至100μmol/L）或载体（二甲基亚砜）处理NEN细胞。采用蛋白质免疫印迹法测定Raf-1/MEK/ERK的激活、其他通路的激活以及细胞生物活性激素的产生。
在NEN细胞中，ZM336372分别通过ERK1/2和GSK-3β的磷酸化导致raf-1激活增加以及糖原合酶激酶-3β（GSK-3β）失活。磷脂酰肌醇3激酶途径的重要介质磷酸化Akt水平没有改变。重要的是，在存在ZM336372的情况下，用强效抑制剂U0126阻断raf-1途径并没有降低p-GSK-3β的水平，这表明GSK-3β失活独立于raf-1途径激活。此外，即使在阻断raf-1途径后，嗜铬粒蛋白A和achaete-scute复合体样-1的减少水平仍然持续存在。在存在针对raf-1的小干扰RNA的情况下用ZM336372处理导致Raf-1产生增加，这表明ZM336372在转录水平上调raf-1。
这是对新型化合物ZM336372调节NEN细胞中多种途径的首次描述。
