Roles of E2F3 and SGO1 in the Epithelial-to-Mesenchymal Transition and Metastasis of Breast Cancer

摘要/摘要 尽管乳腺癌的研究和治疗取得了很大进展，但大约有42,000人 预计2019年美国女性将死于乳腺癌。尤其致命的是基本的，三重的 阴性(TN)乳腺癌。基本的TNBC在非裔美国人和西班牙裔美国人中更为普遍 而且没有生物疗法可用来治疗她们。E2启动子结合 因子(E2F)是一组受视网膜母细胞瘤(RB)控制的八种转录因子， 调节几个细胞过程，包括DNA复制、基因组稳定性和细胞凋亡。 广义地讲，E2F可以分为转录激活剂(那些促进基因的激活剂 转录)和抑制因子(那些停止基因转录的因子)。我在这里提供的初步数据 显示67%的基底/TN乳腺癌过度表达E2F激活子。众所周知，RB 通路参与了上皮向间充质转化(EMT)，这是导致 转移；然而，推动乳腺癌EMT的E2F激活物的参与仍不清楚。 调查。我们发表的数据表明，E2F激活子(E2F1-3)的过度表达 导致有丝分裂调节因子(Mps1、NEK2、SGO1等)表达增加。 此外，我们最近发表了Mps1促进EMT和侵袭以及NEK2(AN E2F靶)在3D培养模型中产生侵袭前突起。因此，我们质疑的是 E2FS激活剂在一定程度上通过SGO1促进EMT、侵袭和转移。 具体地说，我们将重点研究E2F3，因为它在42%的基础乳房中过度表达 癌症和它，我们已经表明，E2F调节SGO1蛋白水平的稳定性。我们的 中心假说是E2F3的过度表达通过促进肿瘤的发生 EMT通过诱导SGO1的转录，从而导致侵袭性增加和 转移。为了验证我们的中心假设，我们将制定以下两个具体目标：(1) 确定E2F3和SGO1在转移性卵巢癌EMT、侵袭和迁移中的作用 阴性的乳腺癌细胞。(2)检测E2F3基因敲除对MDA-MB-231细胞的影响 在NOD SCID伽马小鼠模型中使用CRISPR/Cas9基因组编辑的品系。我们希望 确定E2F3过表达如何通过SGO1促进乳腺EMT的机制 癌症，从而促进迁移、侵袭和转移。如果预期结果是 MET，小分子可能被设计来改进目前的治疗方法，以针对下游 E2F3的效应器，因为E2F不能作为目标。

SUMMARY/ ABSTRACT Despite the great advancements in breast cancer research and treatment, approximately 42,000 US women are expected to die from breast cancer in 2019. Especially deadly are basal, triple- negative (TN) breast cancers. Basal TNBC are more prevalent in African American and Hispanic women and there are no biological therapies available to treat them. The E2 Promoter Binding Factors (E2Fs) are a group of eight transcription factors under retinoblastoma (Rb) control that regulate several cellular processes including DNA replication, genomic stability and apoptosis. Broadly, E2Fs can be divided into transcriptional activators (those that promote gene transcription) and repressors (those that halt gene transcription). Preliminary data I present here shows 67% basal/TN breast cancers overexpress the E2F activators. It is known that the Rb pathway is involved in the epithelial-to-mesenchymal transition (EMT), an early process that lead to metastasis; yet the involvement of the E2F activators driving EMT in breast cancer is still under investigation. Our published data demonstrated that overexpression of E2F activators (E2F1-3) leads to increased expression of mitotic regulators (MPS1, NEK2, SGO1, among others). Furthermore, we recently published that that MPS1 promotes EMT and invasion and NEK2 (an E2F target) generates pre-invasive protrusions in 3D culture models. Hence, we question to what extent deregulation of E2Fs activators promotes EMT, invasion, and metastasis through SGO1. Specifically, we will focus our research in E2F3 because it is overexpressed in 42% basal breast cancers and it we already showed that E2Fs regulate the stability of SGO1 protein levels. Our central hypothesis is that the overexpression of E2F3 contributes to tumorigenesis by promoting EMT through the induction of the transcription of SGO1, thus leading to increased invasion and metastasis. To test our central hypothesis, we will develop the following two specific aims: (1) Determine the effects of E2F3 and SGO1 in EMT, invasion, and migration in metastatic, triple- negative breast cancer cells. (2) Determine the effects of E2F3 knockout in MDA-MB-231 cell lines using CRISPR/Cas9 genome editing in NOD scid gamma mouse models. We expect to identify a mechanism of how E2F3 overexpression promotes EMT through SGO1 in breast cancer, thus contributing to migration, invasion, and metastasis. If the expected outcomes are met, small molecules may be designed to improve current therapies to target downstream effectors of E2F3, since E2Fs cannot be targeted.