Role of microRNAs in intestinal stem cell regulation and cancer initiation

 描述（由申请人提供）：Wnt/β-连环蛋白信号传导对于肠干细胞（ISC）的维持和活化至关重要。导致不受调节的Wnt/β-连环蛋白的突变与肿瘤的发生和生长有关。最近的证据表明，该途径也可能是ISC向癌症干细胞（CSC）转变的关键介导物，其表现出干细胞样特征并有助于转移和对治疗的抗性。经典Wnt信号传导介导肿瘤形成的潜在机制在很大程度上是未知的，但新出现的证据表明APC的缺失或β-连环蛋白的稳定化导致微小RNA（miRNA）的异常表达。miRNAs是一类高度保守的非编码小分子RNA（长度约22个核苷酸），在细胞的稳态和发育中起着重要作用，也可能与肿瘤发生有关。miRNAs是否直接介导Lgr 5 + ISCs的转化尚未研究。为了研究miRNA在Wnt介导的肿瘤形成中的作用，我们对β-连环蛋白稳定后肠隐窝的miRNA表达进行了全面分析。我们的分析确定了五种差异表达的miRNA（let-7 e、miR-96、miR-223、miR-411和miR-423- 5 p），并确定了miRNA下调的总体趋势，这是在人类癌症中观察到的现象。以下具体目的旨在进一步研究miRNA在肠道干细胞调控和癌症发生中的作用。目标1.为了研究通过整体隐窝分析鉴定的特异性miRNAs在 ISC行为。目标二。确定总体miRNA下调对ISC行为和腺瘤形成的影响。总之，该建议旨在描述miRNA及其靶点对ISC行为和腺瘤形成的作用。我们预计这可以为开发新的基于Wnt的生物标志物和肠癌治疗方法提供基础。

 DESCRIPTION (provided by applicant): Wnt/ß-catenin signaling is crucial for maintenance and activation of intestinal stem cells (ISCs). Mutations resulting in unregulated Wnt/ß-catenin have been linked to tumor initiation and growth. Recent evidence suggests that this pathway may also be a key mediator of the transition of ISCs to cancer stem cells (CSCs), which exhibit stem like features and contribute to metastasis and resistance to treatment. The underlying mechanisms by which canonical Wnt signaling mediates tumor formation are largely unknown, but emerging evidence suggests that deletion of APC or stabilization of ß-catenin results in aberrant expression of microRNAs (miRNAs). MiRNAs, a diverse class of highly conserved small non-coding RNAs (~22 nucleotides long), have been shown to play a critical role in cellular homeostasis and development and may also contribute to carcinogenesis. Whether miRNAs directly mediate the transformation of Lgr5+ ISCs has not been explored. To investigate the role of miRNAs in Wnt-mediated tumor formation, we performed global profiling of miRNA expression from intestinal crypts following stabilization of ß-catenin. Our analysis identified five miRNAs (let- 7e, miR-96, miR-223, miR-411 and miR-423-5p) that were differentially expressed and identified a general trend towards down-regulation of miRNAs, a phenomenon observed in human cancers. The following specific aims are designed to further investigate the role of miRNAs in the regulation of intestinal stem cells and the initiation of cancer. Aim 1. To investigate the role of specific miRNAs, identified by global crypt profiling, on ISC behavior. Aim 2. To determine the impact of global miRNA down-regulation on ISC behavior and adenoma formation. In summary, this proposal seeks to delineate the role of miRNAs and their targets on ISC behavior and adenoma formation. We anticipate that this could provide the basis for the development of novel Wnt-based biomarkers and therapeutics for intestinal cancer.