Defining the role of Taiman, the Drosophila homolog of AIB1, as a super-competitor in developing epithelia

项目总结 浸润性乳腺癌是一种致命的疾病，每年导致约42,000名妇女死亡，给美国造成超过 每年165亿美元。导致乳腺癌的复杂的疾病机制仍然不够。 被理解为自信地设计疗法。一种机制正在成为局部入侵的潜在驱动因素 在乳腺癌和其他癌症中存在“细胞竞争”。这种现象发生在两个不同的细胞群 不同的“健康”水平并列在同一组织中。高健康细胞(称为“赢家”)长得更多 通过细胞凋亡，迅速杀死生长较慢的邻居(称为“失败者”)。癌细胞获得“赢家”地位 通过激活致癌基因。赋予“赢家”地位的癌基因被称为“超级竞争者”。我们的实验室使用 模式生物，黑腹果蝇，研究被改变的保守的生长和增殖途径 在人类癌症中。在以前的工作中，我们发现了果蝇Taiman(TAI，人类中的AIB1)，它是一种 蜕皮激素类固醇激素受体(ECR)，是一种候选的超级竞争者，赋予了 细胞通过分泌的促凋亡蛋白Spätzle(SPZ)产生Toll受体配体。我们还有 研究表明，TAI结合了约克(Yki)共激活蛋白，该蛋白是河马肿瘤抑制途径的主要靶点。 而YKI：TAI协同驱动促生长基因的表达。然而，我们并不完全了解如何 TAI驱动邻居杀戮，或者是否需要与ECR和/或YKI互动。此外，将TAI归类为 “超级竞争者”需要证据表明，降低TAI剂量会导致相对于野生型细胞的“失败者”地位。 在以下三个目标中，我将验证我的假设，即TAI通过其 与YKI(河马途径)或ECR(蜕皮激素途径)相互作用，检验TAI过表达的相对适合性 (TaiHigh)、野生型(Tait)和tai亚型(Tailow)细胞，并进行实验以识别细胞竞争 受TAI调控的因子。在目标1中，我将评估升高或降低TAI对同型细胞存活的影响 与异型环境的对比。为了链接到我们发布的数据，我还将调查SPZ/Toll的要求 在这些上下文中的路径。在目标2中，我将使用基于候选人的方法来测试yki/Hippo的需求 和ECR信号在TAI驱动的对邻近细胞的杀伤中。最后，在目标3中，我将使用不偏不倚、基于发现的 方法翻译核糖体亲和纯化测序(TRAP-SEQ)鉴定TAI诱导的TAI 翼细胞中的翻译蛋白质组和其中的候选“竞争”因子。这些目标将定义 上皮组织中TAI调控细胞竞争的分子机制。这项工作还可以揭示 细胞竞争和类固醇激素信号之间的联系，这可能是癌症生物学的一个新元素。 这项工作将发现的途径将产生长期影响，因为细胞竞争的知识 这种机制可以应用于哺乳动物模型，以了解更多关于癌症发生和进展的信息。 具体地说，从这项研究中获得的知识可以使人们更好地理解人类的作用 AIB1同源基因在乳腺癌中的作用，并导致潜在新疗法的开发。

PROJECT SUMMARY Invasive breast cancer is a deadly disease, killing ~42,000 women each year and costing the United States over $16.5 billion annually. The complicated disease mechanisms that drive breast cancer are still insufficiently understood to confidently design therapeutics. One mechanism emerging as a potential driver for local invasion in breast and other cancers is ‘cell competition.’ This phenomenon occurs when two different cell populations with different ‘fitness’ levels are juxtaposed in the same tissue. High fitness cells (called ‘winners’) grow more rapidly and kill off slower growing neighbors (called ‘losers’) by apoptosis. Cancer cells acquire ‘winner’ status by activating oncogenes. Oncogenes that confer ‘winner’ status are called ‘super-competitors.’ Our lab uses the model organism, Drosophila melanogaster, to study conserved growth and proliferation pathways that are altered in human cancer. In previous work we showed that Drosophila Taiman (Tai, AIB1 in humans), a co-activator of the Ecdysone steroid hormone receptor (EcR), is a candidate super-competitor and imparts ‘winner’ status to cells via production of the secreted, pro-apoptotic protein Spätzle (Spz), a Toll receptor ligand. We have also shown that Tai binds the Yorkie (Yki) coactivator protein, the main target of the Hippo tumor suppressor pathway, and that Yki:Tai collaboratively drive expression of pro-growth genes. However, we do not fully understand how Tai drives neighbor killing, or whether it requires interactions with EcR and/or Yki. Moreover, classifying Tai as a ‘super-competitor’ requires evidence that lowering the Tai dose confers ‘loser’ status relative to wildtype cells. In the following three Aims, I will test my hypothesis that Tai acts as a super-competitor through either its interaction with Yki (Hippo pathway) or EcR (ecdysone pathway), test the relative fitness of Tai-overexpressing (Taihigh), wildtype (Taiwt), and Tai hypomorphic (Tailow) cells, and carry out experiments to identify cell competition factors regulated by Tai. In Aim 1, I will assess the effects of elevated or reduced Tai on cell survival in homotypic vs. heterotypic environments. To link to our published data, I will also investigate the requirement of the Spz/Toll pathway in these contexts. In Aim 2, I will use candidate-based approaches to test the requirements for Yki/Hippo and EcR signaling in Tai-driven killing of neighbor cells. Finally in Aim 3, I will use the unbiased, discovery-based method Translating Ribosome Affinity Purification with sequencing (TRAP-Seq) to identify the Tai-induced translated proteome in wing cells and candidate ‘competition’ factors within it. These aims will define the molecular mechanisms underlying Tai-regulated cell competition in epithelial tissue. This work could also reveal a link between cell competition and steroid hormone signaling, which could be a novel element of cancer biology. The pathways that will be uncovered by this work will have long-term impacts, as knowledge of cell competition mechanisms could be applied to mammalian models to learn more about cancer emergence and progression. Specifically, knowledge gained from this research could lead to greater understanding of the role of the human homolog AIB1 in breast cancer and lead to the development of potential new therapeutics.