Altered differentiation and paracrine stimulation of mammary epithelial cell proliferation by conditionally activated Smoothened.
Altered differentiation and paracrine stimulation of mammary epithelial cell proliferation by conditionally activated Smoothened.
复制标题
通过条件激活的 Smoothened 改变乳腺上皮细胞增殖的分化和旁分泌刺激。
DOI：
10.1016/j.ydbio.2011.01.025
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发表时间：
2011
影响因子：
2.7
通讯作者：
Lewis,MichaelT
中科院分区：
文献类型：
--
作者：
Visbal,AdrianaP;LaMarca,HeatherL;Villanueva,Hugo;Toneff,MichaelJ;Li,Yi;Rosen,JeffreyM;Lewis,MichaelT
Hedgehog（Hh）信号网络对于哺乳动物的模式化和器官形成至关重要，并且已经涉及多种癌症。Smoothened（Smo），编码主要信号转导的基因，在乳腺癌中频繁过表达，MMTV-SmoM 2转基因小鼠中的组成性激活引起乳腺形态学改变，增殖增加和干/祖细胞数量变化。在转基因小鼠和临床标本中，增殖细胞通常不表达可检测的Smo，这表明Smo以非细胞自主方式刺激增殖的假设。在这里，我们采用了一个基因标记的小鼠模型携带Cre重组酶依赖条件等位基因的组成型活性Smo（SmoM 2）来测试这一假设。MMTV-Cre-或腺病毒-Cre-介导的SmoM 2在腔上皮中的表达，而不是在肌上皮中的表达，是过度增殖表型所需的。在邻近或紧邻Smo表达细胞的细胞中观察到高水平的增殖，表明SmoM 2表达细胞通过旁分泌或旁分泌机制刺激增殖。与此相反，Smo表达改变了细胞自主的方式管腔细胞分化。与野生型细胞相比，通过荧光激活细胞分选（FACS）经由遗传荧光标签纯化的SmoM 2表达细胞表达高水平的Ptch 2、Gli 1、Gli 2、Jag 2和Dll-1，以及较低水平的Notch 4和Hes 6。这些研究为Smo在乳腺中的激活机制及其在乳腺肿瘤发生中的可能作用提供了新的见解。此外，这些结果也有潜在的影响，通常在其他器官中观察到的刺猬信号激活的结果的增殖表型的解释。
The Hedgehog (Hh) signaling network is critical for patterning and organogenesis in mammals, and has been implicated in a variety of cancers. Smoothened (Smo), the gene encoding the principal signal transducer, is overexpressed frequently in breast cancer, and constitutive activation in MMTV-SmoM2 transgenic mice caused alterations in mammary gland morphology, increased proliferation, and changes in stem/progenitor cell number. Both in transgenic mice and in clinical specimens, proliferative cells did not usually express detectable Smo, suggesting the hypothesis that Smo functioned in a non-cell autonomous manner to stimulate proliferation. Here, we employed a genetically tagged mouse model carrying a Cre-recombinase-dependent conditional allele of constitutively active Smo (SmoM2) to test this hypothesis. MMTV-Cre- or adenoviral-Cre-mediated SmoM2 expression in the luminal epithelium, but not in the myoepithelium, was required for the hyper-proliferative phenotypes. High levels of proliferation were observed in cells adjacent or in close-proximity to Smo expressing cells demonstrating that SmoM2 expressing cells were stimulating proliferation via a paracrine or juxtacrine mechanism. In contrast, Smo expression altered luminal cell differentiation in a cell-autonomous manner. SmoM2 expressing cells, purified by fluorescence activated cell sorting (FACS) via the genetic fluorescent tag, expressed high levels of Ptch2, Gli1, Gli2, Jag2 and Dll-1, and lower levels of Notch4 and Hes6, in comparison to wildtype cells. These studies provide insight into the mechanism of Smo activation in the mammary gland and its possible roles in breast tumorigenesis. In addition, these results also have potential implications for the interpretation of proliferative phenotypes commonly observed in other organs as a consequence of hedgehog signaling activation.