MicroRNA-200 family regulation by the apical-basal polarity complexes in EMT and

描述（由申请人提供）：肺癌是癌症相关死亡的主要原因，主要是由于转移性疾病。发展更好的转移预防和治疗方案将需要更好地了解肿瘤进展和转移的具体事件。我们已经证明，表达人类肺癌中常见的突变（KrasG12D和p53R172H）的小鼠会发生转移性肺腺癌。从这些小鼠肿瘤中分离的细胞系在皮下注射到同基因小鼠后，转移的频率高或低，这取决于microRNA-200 （miR-200）家族成员的表达。由于miR-200成员抑制Zeb家族的转录抑制因子，miR-200表达的缺失导致上皮-间质转化（EMT）基因和转移的上调。与EMT一致，易转移的肿瘤细胞失去上皮极性复合物的表达，miR-200的强制表达恢复上皮极性并消除转移。反过来，在不具备转移能力的细胞中，低敲低基底侧极性复合物scribble的关键成分会抑制miR-200，增加Zeb-1，并诱导转移。这些发现表明细胞极性、miR-200和转移之间存在明显的相互作用。我们的总体假设是，维持miR-200水平，从而抑制癌细胞EMT和转移需要功能性的顶基底极性复合物。我们将通过完成两个目的来检验这一假设：目的1将确定scribble-deficient肿瘤的侵袭和转移是否完全是由于mir -200介导的Zeb1抑制缺失所致；目的2将确定miR-200抑制和转移在潦草缺失的肿瘤中是否由于潦草本身的缺失，更大的基底外侧复合体的功能障碍，包括潦草（Scrib），大圆盘（Dlg1）和致命的巨型幼虫（Lgl1）蛋白，或基底外侧复合体与尖极性复合体的异常相互作用，包含屑同源物3 （Crb3）或分配缺陷6 （Pard6）。将使用2D和3D体外模型结合以及同基因动物研究来开展这项工作，目的是了解顶基极性因子如何通过miR-200功能调节细胞表型。

DESCRIPTION (provided by applicant): Lung cancer is the leading cause of cancer-related mortality, primarily due to metastatic disease. Developing improved metastasis prevention and treatment options will require a better understanding of the specific events involved in tumor progression and metastasis. We have shown that mice expressing mutations commonly found in human lung cancer (KrasG12D and p53R172H) develop metastatic lung adenocarcinomas. Cell lines isolated from tumors in these mice metastasize with high or low frequency following subcutaneous injection into syngeneic mice, dependent upon the expression of the microRNA-200 (miR-200) family members. Since the miR-200 members repress the Zeb family of transcriptional repressors, loss of miR-200 expression results in upregulation of epithelial-to-mesenchymal transition (EMT) genes and metastasis. Coincident with EMT, the metastasis-prone tumor cells lose expression of epithelial polarity complexes, and forced expression of miR-200 restores epithelial polarity and abrogates metastasis. Reciprocally, knockdown of a key component of the basolateral polarity complex, scribble, in a metastasis-incompetent cell suppresses miR-200, increases Zeb-1, and induces metastasis. These findings demonstrate a clear interplay between cell polarity, miR-200, and metastasis. Our global hypothesis is that functional apical-basal polarity complexes are required to maintain miR-200 levels and thereby suppress cancer cell EMT & metastasis. We will test this hypothesis by completing two Aims: Aim 1 will determine whether invasion and metastasis in scribble-deficient tumors is due entirely to loss of miR-200-mediated suppression of Zeb1; Aim 2 will determine whether miR-200 suppression and metastasis in the scribble-deficient tumors is due to loss of scribble itself, dysfunction of the larger basolateral complex, which includes the scribble (Scrib), discs large (Dlg1), and lethal giant larvae (Lgl1) proteins, or aberrant interactions of the basolateral complex with the apical polarity complexes, containing the crumbs homolog 3 (Crb3) or partitioning defective 6 (Pard6). A combination of 2D and 3D in vitro models, and syngeneic animal studies will be used to carry out this work, with the aim of understanding how the apical- basal polarity factors regulate cell phenotype through miR-200 fucntion. PUBLIC HEALTH RELEVANCE: Lung cancer is the leading cause of cancer mortality in the U.S., due mainly to the impact of disease metastasis to distant organs. Herein we propose to work with a new combination of in vitro and in vivo models to better understand the process of metastasis. Specifically we plan to study how migratory and invasive characteristics of the tumor are controlled by proteins that determine cellular architecture and cell-cell interaction.