Mechanism of ATF5 addition in breast cancer

项目摘要 ATF 5是乳腺癌细胞存活所必需的，但在其非转化的乳腺癌细胞中是不稳定的。 同行ATF 5具有这种转化依赖性促存活功能的原因完全是 未知了解如何ATF 5是乳腺癌细胞生存的独特需要将新的 癌细胞的脆弱性，并帮助他们的选择性建设设计策略。我们的研究表明， 当ATF 5被Src磷酸化并与NF κ B复合时，激活ATF 5、NF κ B和NF κ B的转录， c-Src。因此，我们假设1）NFkB是ATF 5-NFkB异二聚体的强制性配偶体 转录因子，其负责ATF 5、NFkB和c-Src的转录; 2）c-Src激活 通过磷酸化ATF 5上的免疫受体酪氨酸激活基序（ITAM）， 一种自我刺激反馈机制，维持ATF 5和Src活性的升高，使Src-Ras 信号传导;和3）由于转化细胞中异常的Src活化，ATF 5被ITAM磷酸化，即， 只有在转化的细胞中才被激活。ATF 5激活与Src-Ras升高之间的相互依赖性 促进细胞存活和转化细胞增殖的信号传导使ATF 5“成瘾”， 癌细胞我们将进一步测试破坏ATF 5-NFkB相互作用或阻断ATF 5 ITAM的想法， 磷酸化消除转化细胞中的Ras信号传导并引起细胞死亡。我们的长期目标是 确定ATF 5的转化依赖性促存活功能的分子机制 并开发新的策略来选择性地杀死乳腺癌细胞。在此，我们提出两个具体目标： 目的1：确定ATF 5激活乳腺癌细胞Ras信号的机制。具体地说， 我们将a）确定ATF 5和NFkB如何协同调节ATF 5、NFkB和c-Src的转录， B）确定ATF 5 ITAM磷酸化对ATF 5依赖性基因的影响 在乳腺癌细胞中的ATF 5、NFkB和c-Src的转录。目的2：选择性破坏乳腺癌细胞， 靶向ATF 5/Ras通路。具体地，我们将a）确定中断ATF 5-NFkB相互作用是否 在转化的HBEC中有效阻断Ras信号传导并诱导细胞死亡，但在非转化的HBEC中不诱导细胞死亡。 B）确定阻断ATF 5 ITAM磷酸化是否选择性地诱导乳腺癌中的细胞死亡; 癌细胞和抑制小鼠模型中乳腺癌的发展。这些目标的实现将揭示 ATF 5的转化依赖性促生存功能的基础机制，并找到新的策略 用于选择性破坏乳腺癌细胞的癌症治疗。这项研究将为本科生提供 学生和药学博士的学生在科学和医学的研究机会，缓解了在 我们的地区-西北内陆-在那里，这些学生中的大多数没有获得研究以外， 本科实验课程。

Project Summary ATF5 is required for the survival of breast cancer cells but is dispensable in their non-transformed counterparts. The reason for ATF5 to have such transformation-dependent pro-survival function is completely unknown. Understanding how ATF5 is uniquely required for the survival of breast cancer cells will new vulnerabilities of cancer cells and help design strategies for their selective construction. Our studies show that ATF5, when phosphorylated by Src and complexed with NFkB, activates the transcription of ATF5, NFkB, and c-Src. Consequently, we hypothesize that 1) NFkB is an obligatory partner for an ATF5-NFkB heterodimer transcription factor, which is responsible for the transcription of ATF5, NFkB, and c-Src; 2) c-Src activates ATF5 by phosphorylating the immunoreceptor tyrosine-based activation motif (ITAM) on ATF5, which creates an auto-stimulatory feedback mechanism sustaining elevated ATF5 and Src activity, perpetuating Src-Ras signaling; and 3) Due to aberrant Src activation in transformed cells, ATF5 is ITAM-phosphorylated, i.e., activated, only in transformed cells. The interdependence between activation of ATF5 and elevated Src-Ras signaling, which promotes cell survival and proliferation of transformed cells, renders ATF5 “addicted” in cancer cells. We will further test the ideas that disruption of ATF5-NFkB interaction or blocking ATF5 ITAM phosphorylation abrogate Ras signaling in transformed cells and cause cell death. Our long-term goal is to determine the molecular mechanism that underlies the transformation-dependent pro-survival function of ATF5 and to develop new strategies to selectively kill breast cancer cells. Here, we propose the two Specific Aims: Aim 1: Determine the mechanism by which ATF5 activates Ras signaling in breast cancer cells. Specifically, we will a) determine how ATF5 and NFkB cooperate to regulate the transcription of the ATF5, NFkB, and c-Src genes in breast cancer cells; b) determine the effect of ATF5 ITAM phosphorylation on ATF5-dependent gene transcription of ATF5, NFkB, and c-Src in breast cancer cells. Aim 2: Selectively destroy breast cancer cells by targeting the ATF5/Ras pathway. Specifically, we will a) determine whether interrupting ATF5-NFkB interaction effectively blocks Ras signaling and induce cell death in transformed HBECs but not in non-transformed HBECs; b) determine whether blocking ATF5 ITAM phosphorylation selectively induces cell death in breast cancer cells and inhibit breast cancer development in mouse models. Completion of these aims will reveal the mechanism that underlies the transformation-dependent pro-survival function of ATF5 and find new strategies for cancer therapy that can selectively destroy breast cancer cells. This research will provide undergraduate students and PharmD students with research opportunities in science and medicine, alleviating a situation in our area—the Inland Northwest—where most of these students have no access to research other than undergraduate laboratory courses.