Reciprocal regulation of RhoA and RhoC characterizes the EMT and identifies RhoC as a prognostic marker of colon carcinoma
Reciprocal regulation of RhoA and RhoC characterizes the EMT and identifies RhoC as a prognostic marker of colon carcinoma
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DOI：
10.1038/sj.onc.1209682
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发表时间：
2006-11-01
期刊：
影响因子：
8
通讯作者：
Mercurio, A. M.
中科院分区：
文献类型：
--
作者：
Bellovin, D. I.;Simpson, K. J.;Mercurio, A. M.
了解 RhoC 表达和激活的调节机制对于破译 RhoC 对肿瘤发生的贡献至关重要。在这里，我们报道 RhoC 表达和激活是由结肠癌的上皮间质转化 (EMT) 诱导的。使用 LIM 1863 结肠癌细胞，检测到 RhoC 蛋白表达和随后的激活与 E-钙粘蛋白的丢失和间充质特征的获得同时发生。在 RhoC 启动子中鉴定出了几个 Ets-1 结合位点，并通过染色质免疫沉淀获得了 Ets-1 可以在 EMT 期间调节 RhoC 表达的证据。有趣的是，观察到与 EMT 相关的 RhoA 激活显着减少，这对应于 RhoC 表达的增加。 shRNA 的使用证实 RhoA 抑制 EMT 后细胞迁移，而 RhoC 促进 EMT 后细胞迁移，证明它们的协调调节具有功能意义。为了评估 RhoC 表达在结肠癌中的重要性，对 566 个临床结果已知的结直肠肿瘤进行了免疫组织化学分析。 RhoC 水平从无表达到高表达，统计分析表明，RhoC 表达升高与不良预后以及 E-钙粘蛋白的异常表达和定位相关。这些数据提供了 RhoC 表达在结肠癌中如何调节的一种机制，并证实了其作为预后标志物的实用性。
Understanding how RhoC expression and activation are regulated is essential for deciphering its contribution to tumorigenesis. Here, we report that RhoC expression and activation are induced by the epithelial to mesenchymal transition (EMT) of colon carcinoma. Using LIM 1863 colon cancer cells, RhoC protein expression and subsequent activation were detected coincident with the loss of E-cadherin and acquisition of mesenchymal characteristics. Several Ets-1 binding sites were identified in the RhoC promoter, and evidence was obtained using chromatin immunoprecipitation that Ets-1 can regulate RhoC expression during the EMT. Interestingly, a marked decrease in RhoA activation associated with the EMT was observed that corresponds to the increase in RhoC expression. Use of shRNA established that RhoA inhibits and RhoC promotes post-EMT cell migration, demonstrating functional significance for their coordinate regulation. To assess the importance of RhoC expression in colon cancer, immunohistochemistry was performed on 566 colorectal tumors with known clinical outcome. The level of RhoC ranged from no expression to high expression, and statistical analysis revealed that elevated RhoC expression correlates with poor outcome as well as aberrant expression and localization of E-cadherin. These data provide one mechanism for how RhoC expression is regulated in colon carcinoma and substantiate its utility as a prognostic marker.