Identification and characterization of genetic regulators in cancer stem cell

描述（由申请人提供）：乳腺癌干细胞已被鉴定为CD 44？/低乳腺肿瘤细胞，仅保留在小鼠模型中形成新肿瘤的能力。癌症干细胞可以直接由正常干细胞的突变产生，或者由导致干细胞特性恢复的祖细胞的突变产生。虽然在乳腺上皮分化过程中通常下调，但CD 44在高达85%的人乳腺癌中表达，并且已显示CD 44的异位表达促进转移。乳腺干细胞中CD 44的失调可能与由于调节CD 44表达的途径突变而导致的致瘤性转化有关。因此，研究乳腺干细胞中调节CD 44表达和干细胞分化过程中控制CD 44下调的分子机制是非常重要的。基因表达可以由遗传元件（例如，顺式调节剂，即，控制基因的细胞类型特异性表达/抑制的非编码DNA序列），以及表观遗传控制如DNA甲基化。由于基因组的高度复杂性，在脊椎动物中发现决定细胞类型特异性（干细胞与分化细胞）基因表达的顺式调节子仍然是一项艰巨的任务。然而，事实上，许多顺式调节剂往往是进化保守的物种提供了一个基础，这些顺式调节剂的鉴定使用比较基因组学方法。我们的方法采用计算机预测和“湿实验室”验证方法，以确定关键的顺式调节和反式作用因子的CD 44基因是高度创新的。进化保守的非编码区的预测顺式调节大大减少了假阳性，因此，实验验证的工作量。它提供了一个完整的方法来解码复杂的转录调控的CD 44。了解CD 44表达的调控机制可能最终导致识别在乳腺干细胞或分化层次进一步下降的细胞的致瘤转化期间可能发生突变的途径，从而可能为乳腺癌的治疗提供新的治疗靶点。公共卫生相关性：该提案的目标是剖析调节乳腺癌干细胞标志物CD 44表达的分子机制。了解CD 44表达的调节机制可能最终导致识别在乳腺干细胞或分化层次进一步下降的细胞的致瘤转化期间可能发生突变的途径，从而为乳腺癌的治疗提供新的治疗靶点，直接瞄准肿瘤的起源

DESCRIPTION (provided by applicant): Breast cancer stem cells have been identified as CD44?/low breast tumor cells that exclusively retain the ability to form new tumors in mouse models. Cancer stem cells can arise from mutations in normal stem cells directly, or from mutations in progenitor cells that lead to the regaining of stem cell property. Although normally down-regulated during mammary epithelial differentiation, CD44 is expressed in up to 85% human breast cancers and the ectopic expression of CD44 has been shown to promote metastasis. It is possible that the deregulation of CD44 in breast stem cell is associated with tumorigenic transformation due to mutations in pathways that regulate CD44 expression. Therefore it is extremely important to dissect the molecular mechanism(s) that regulates CD44 expression in breast stem cells and controls CD44 down-regulation during stem cell differentiation. Gene expression can be controlled by genetic elements (e.g., cis-regulators, i.e., non- coding DNA sequences that control cell type-specific expression/suppression of genes), in addition to epigenetic controls such as DNA methylation. Due to the highly complex nature of the genome, finding cis-regulators, which determine cell type-specific (stem cells versus differentiated cell) gene expression, in vertebrates remains a difficult task. However, the fact that many cis-regulators are often evolutionarily conserved across species provides a basis for the identification of these cis-regulators using comparative genomic method. Our approach employing in silico predication and "wet lab" verification methods to identify crucial cis-regulators and trans-acting factors of the CD44 gene is highly innovative. Evolutionarily conserved non-coding regions for the prediction of cis-regulators greatly reduced false positives, hence, work load for experimental verification. It provides an integrative way to decode the complicated transcriptional regulation of CD44. Understanding regulatory mechanisms of CD44 expression could ultimately lead to the identification of pathways that could be mutated during the tumorigenic transformation of breast stem cells or cells further down the differentiation hierarchy and thus may provide new therapeutic targets for treatment of breast cancer. PUBLIC HEALTH RELEVANCE: The goal of this proposal is to dissect molecular mechanisms that regulate the expression of the breast cancer stem cell marker CD44 .Understanding regulatory mechanisms of CD44 expression could ultimately lead to the identification of pathways that could be mutated during tumorigenic transformation of breast stem cells or cells further down the differentiation hierarchy and thus provide novel therapeutic targets for treatment of breast cancer, aimed directly at the origin of the tumor.