Medical Genome Research Center, Korea Research Institute of Bioscience and Biotechnology, Yuseong, Daejeon 305-806, Korea.
Carcinogenesis. 2011 Mar;32(3):254-61. doi: 10.1093/carcin/bgq244. Epub 2010 Nov 17.
RhoB expression is reduced in most invasive tumors, with loss of RhoB expression correlating significantly with tumor stage. Here, we demonstrate that upregulation of RhoB by the potent anticancer agent NSC126188 induces apoptosis of NUGC-3 human gastric carcinoma cells. The crucial role of RhoB in NSC126188-induced apoptosis is indicated by the rescue of NUGC-3 cells from apoptosis by knockdown of RhoB. In the presence of NSC126188, c-Jun N-terminal kinase (JNK) signaling was activated, and the JNK inhibitor SP600125 reduced RhoB expression and suppressed the apoptosis of NUGC-3 cells. Knockdowns of mitogen-activated protein kinase kinase (MKK) 4/7, JNK1/2 and c-Jun downregulated RhoB expression and rescued cells from apoptotic death in the presence of NSC126188. The JNK inhibitor SP600125 suppressed transcriptional activation of RhoB in the presence of NSC126188, as indicated by a reporter assay that used luciferase under the RhoB promoter. The ability of NSC126188 to increase luciferase activity through both the p300-binding site and the inverted CCAAT sequence (iCCAAT box) suggests that JNK signaling to upregulate RhoB expression is mediated through both the p300-binding site and the iCCAAT box. However, the JNK inhibitor SP600125 did not inhibit the upregulation of RhoB by farnesyltransferase inhibitor (FTI)-277. The p300-binding site did not affect activation of the RhoB promoter by FTI-277 in NUGC-3 cells, suggesting that the transcriptional activation of RhoB by NSC126188 occurs by a different mechanism than that reported for FTIs. Our data indicate that NSC126188 increases RhoB expression via JNK-mediated signaling through a p300-binding site and iCCAAT box resulting in apoptosis of NUGC-3 cells.
RhoB 表达在大多数侵袭性肿瘤中降低，RhoB 表达的缺失与肿瘤分期显著相关。在这里，我们证明了强效抗癌药物 NSC126188 通过上调 RhoB 诱导 NUGC-3 人胃癌细胞凋亡。通过 RhoB 敲低挽救 NUGC-3 细胞免于凋亡，表明 RhoB 在 NSC126188 诱导的凋亡中起着关键作用。在 NSC126188 的存在下，c-Jun N 端激酶 (JNK) 信号被激活，而 JNK 抑制剂 SP600125 降低了 RhoB 的表达并抑制了 NUGC-3 细胞的凋亡。丝裂原活化蛋白激酶激酶 (MKK) 4/7、JNK1/2 和 c-Jun 的敲低下调了 RhoB 的表达，并在 NSC126188 存在的情况下挽救细胞免于凋亡性死亡。JNK 抑制剂 SP600125 抑制了 RhoB 的转录激活，这在 RhoB 启动子下使用荧光素酶的报告基因实验中得到了证实。NSC126188 通过 p300 结合位点和反向 CCAAT 序列 (iCCAAT 盒) 增加荧光素酶活性的能力表明，JNK 信号转导上调 RhoB 表达是通过 p300 结合位点和 iCCAAT 盒介导的。然而，JNK 抑制剂 SP600125 并没有抑制 Farnesyltransferase 抑制剂 (FTI)-277 对 RhoB 的上调。在 NUGC-3 细胞中，p300 结合位点并不影响 FTI-277 对 RhoB 启动子的激活，这表明 NSC126188 通过不同于 FTI 的机制激活 RhoB 启动子。我们的数据表明，NSC126188 通过 JNK 介导的信号转导通过 p300 结合位点和 iCCAAT 盒增加 RhoB 的表达，导致 NUGC-3 细胞凋亡。
