LIN28 and RNA Uridylation in Breast Cancer: Mouse Models and Molecular Analyses

项目总结/摘要 寻找更有效的癌症疗法的一个主要限制是识别和开发新的靶点， 合理的药物设计最近的和挑衅性的证据暗示了一种新的形式的转录后基因调控 涉及由末端尿苷酰转移酶（TUTases）介导的3' RNA尿苷酸化作为关键基因调节剂， 肿瘤发生的驱动因素。这些数据表明，TUTase活性失调单独和与癌胎儿 LIN 28/let-7通路是多种癌症类型预后不良的标志。大约15%的癌症 重新激活致癌LIN 28表达（LIN 28 A或LIN 28 B），并且这些癌症的典型特征是低表达性。 预后在功能上，LIN 28直接阻断肿瘤抑制因子let-7 microRNA家族的生物发生。最近， 我们发现了封锁背后的机制值得注意的是，TUTase ZCCHC 11通过与LIN 28 A 通过阻止前体let-7转化成其成熟的肿瘤抑制剂形式而使let-7失活。此外，本发明还提供了一种方法， TUTase ZCCHC 11的过表达与预后不良的乳腺癌有关，与LIN 28/let-7无关。 通路引人注目的是，最近的一份报告表明，许多多聚腺苷酸化的mRNA经常在其3'端尿苷酸化 以基因特异性的方式并靶向降解;然而，这一观察结果与癌症的相关性目前尚不清楚。 未知因此，我们的研究有三个主要目标。第一个目标是开发新的临床前小鼠模型 对于LIN 28阳性乳腺癌。这些小鼠模型将阐明LIN 28如何改变疾病进展， 成为评估针对这种癌症类型的新药的宝贵资源。第二个目标是确定是否 使用条件性小鼠敲除，在成年小鼠中Zcchc 11的生物体范围的损失具有表型后果。我们 已发表的关于成年小鼠中Lin 28 A或Lin 28 B的条件失活的工作表明， 这表明抑制任何一种基因都不太可能对患者造成有害的副作用。的 最后一个目标是确定TUTase Zcchc 11的缺失是否抑制Lin 28 A +/Her 2+和Lin 28 A-/Her 2+小鼠乳腺癌 肿瘤的这项研究将是第一个证明TUTase损失在免疫活性细胞中影响肿瘤的原理。 哺乳动物的研究，并解决了用TUTase ZCCHC 11的特异性抑制剂治疗的癌症患者中可能的副作用。 这项工作为癌症研究的新领域奠定了基础， 包括TUTases作为癌症基因调节剂，并探索了靶向抑制肿瘤的新型药物类别的可行性。 LIN 28或TUTases。除了癌症，我们对LIN 28/let-7通路调节因子的研究对于癌症的发生和发展具有重要意义。 干细胞生物学、组织修复、生育力、生长、葡萄糖代谢、2型糖尿病以及诱导的 多能干细胞此外，我们对3' RNA尿苷化的全基因组分析对其他人类 其中功能失调的RNA周转促成病理学的疾病，如多发性骨髓瘤和帕尔曼综合征。

PROJECT SUMMARY / ABSTRACT A major limitation in finding more effective cancer therapies is the identification and exploitation of novel targets for rational drug design. Recent and provocative evidence implicates a novel form of post-transcriptional gene regulation involving 3’ RNA uridylation mediated by Terminal Uridylyl Transferases (TUTases) as a critical gene regulator and driver of tumorigenesis. These data indicate that dysregulated TUTase activity alone and in concert with the onco-fetal LIN28/let-7 pathway are hallmarks of poor prognosis in multiple cancer types. Approximately 15% of all cancers reactivate oncogenic LIN28 expression (either LIN28A or LIN28B) and these cancers are typically characterized by poor prognosis. Functionally, LIN28 directly blocks the biogenesis of the tumor suppressor let-7 microRNA family. Recently, we discovered the mechanism behind this blockade. Notably, the TUTase ZCCHC11 through an association with LIN28A inactivates let-7 by preventing the conversion of precursor let-7 into its mature, tumor suppressor form. In addition, overexpression of the TUTase ZCCHC11 is implicated in poor prognosis breast cancer independently of the LIN28/let-7 pathway. Strikingly, a recent report has shown that many polyadenylated mRNAs are frequently uridylated at their 3’ ends in a gene-specific manner and targeted for degradation; however, this observation’s relevance to cancer is currently unknown. Therefore, our research has three major objectives. The first goal is to develop novel preclinical mouse models for LIN28-positive breast cancers. These mouse models will elucidate how LIN28 modifies disease progression and will be an invaluable resource to evaluate new drugs targeted to this cancer type. The second goal is to determine whether organism-wide loss of Zcchc11 in adult mice has phenotypic consequences using a conditional mouse knockout. Our published work on conditional inactivation of either Lin28A or Lin28B in adult mice demonstrate that both genes are dispensable in adults, suggesting that inhibiting either gene is unlikely to cause deleterious side effects in patients. The last goal is to determine if loss of the TUTase Zcchc11 inhibits Lin28A+/Her2+ and Lin28A-/Her2+ mouse mammary tumors. This research will be the first proof-of-principle that TUTase loss affects tumors in an immunocompetent mammal and addresses possible side-effects in cancer patients treated with specific inhibitors of the TUTase ZCCHC11. This work lays the foundation for new fields of cancer investigations by dramatically shifting the current paradigm to include TUTases as cancer gene regulators and explores the feasibility of a novel drug class targeted at inhibition of LIN28 or TUTases. In addition to cancer, our investigation of regulators of the LIN28/let-7 pathway holds significance for stem cell biology, tissue repair, fertility, growth, glucose metabolism, Type 2 diabetes, and the generation of induced pluripotent stem cells. Moreover, our genome-wide analysis of 3’ RNA uridylation has implications for other human diseases where dysfunctional RNA turnover contributes to pathology such as multiple myeloma and Perlman syndrome.