Hedgehog signaling drives cellular survival in human colon carcinoma cells.
Hedgehog signaling drives cellular survival in human colon carcinoma cells.
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DOI：
10.1158/0008-5472.can-10-2315
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发表时间：
2011-02-01
期刊：
影响因子：
11.2
通讯作者：
Houghton JA
中科院分区：
文献类型：
--
作者：
Mazumdar T;DeVecchio J;Shi T;Jones J;Agyeman A;Houghton JA
Hedgehog（HH）信号传导的异常激活涉及许多人类癌症。经典HH信号传导的特征在于Gli 1和Gli 2的Smoothened（Smo）依赖性激活，其转录调节靶基因。Gli 1和Gli 2的小分子抑制剂GANT 61用于阻断表达HH信号传导组分的人结肠癌细胞系中的HH信号传导。GANT 61给药在5/6个细胞系中诱导稳健的细胞毒性，在剩余的1个细胞系中诱导中等的细胞毒性。相比之下，经典的Smo抑制剂，环巴胺，诱导适度的细胞毒性。此外，GANT 61处理消除了所有6种人结肠癌细胞系的克隆形成性。对GANT 61诱导HT 29细胞毒性的分子机制的分析表明，Fas表达增加，PDGFRα表达减少，PDGFRα也调节Fas。此外，GANT 61处理后，DR 5表达增加，而Bcl-2（Gli 2的直接靶点）下调。shRNA对Gli 1的抑制模拟了GANT 61处理细胞中观察到的基因表达变化。显性负性FADD（消除Fas/DR 5介导的死亡受体信号传导）和/或Bcl-2（阻断Fas介导的细胞凋亡）的过表达部分挽救了GANT 61诱导的HT 29细胞的细胞毒性。因此，激活的Gli基因抑制DR 5和Fas的表达，同时上调Bcl-2和PDGFRα的表达，以抑制Fas并促进细胞存活。总的来说，这些结果突出了Smo下游Gli激活作为人结肠癌模型中治疗靶点的重要性。
Aberrant activation of Hedgehog (HH) signaling is implicated in many human cancers. Classical HH signaling is characterized by Smoothened (Smo)-dependent activation of Gli1 and Gli2, which transcriptionally regulate target genes. A small molecule inhibitor of Gli1 and Gli2, GANT61, was used to block HH signaling in human colon carcinoma cell lines that express HH signaling components. GANT61 administration induced robust cytotoxicity in 5/6 cell lines and moderate cytotoxicity in the remaining 1 cell line. In comparison, the classical Smo inhibitor, cyclopamine, induced modest cytotoxicity. Further, GANT61 treatment abolished the clonogenicity of all 6 human colon carcinoma cell lines. Analysis of the molecular mechanisms of GANT61-induced cytotoxicity in HT29 cells, demonstrated increased Fas expression and decreased expression of PDGFRα, which also regulates Fas. Furthermore, DR5 expression was increased while Bcl-2 (direct target of Gli2) was down-regulated following GANT61 treatment. Suppression of Gli1 by shRNA mimicked the changes in gene expression observed in GANT61-treated cells. Overexpression of dominant negative FADD (to abrogate Fas/DR5-mediated death receptor signaling) and/or Bcl-2 (to block mitochondria-mediated apoptosis) partially rescued GANT61-induced cytotoxicity in HT29 cells. Thus, activated Gli genes repress DR5 and Fas expression while up-regulating Bcl-2 and PDGFRα expression to inhibit Fas and facilitate cell survival. Collectively, these results highlight the importance of Gli activation downstream of Smo as a therapeutic target in models of human colon carcinoma.