The Role of Long Non-coding RNAs in EMT and Cancer Stem Cells

应聘者：Jason Herschkowitz博士是北卡罗来纳大学教堂山分校Charles Perou博士实验室的一名研究生，他的研究生涯始于此。他的研究重点是对人类乳腺癌亚型和基因工程小鼠乳腺肿瘤模型进行大规模基因组比较。这项研究表明，尽管没有一个单一的小鼠模型概括了给定人类亚型的所有表达特征，但人类亚型的许多定义特征在小鼠模型中是保守的，为其临床前应用提供了洞察力。杰森随后转到贝勒医学院(BCM)，在杰弗里·罗森博士的实验室做博士后研究员。在那里，他专注于研究最初在他的研究生工作中发现的克拉丁低亚型乳腺癌。利用一种独特的小鼠模型，他已经确定，与该模型中出现的其他亚型肿瘤相比，克拉丁低的肿瘤富含功能性癌症干细胞(CSCs)。杰森的研究生培训为他提供了癌症基因组学和老鼠模型方面的专业知识。他的博士后工作使他获得了干细胞研究、乳腺发育和肿瘤发生方面的知识和技能。Jason的短期职业目标是现在将他所学的东西应用到长非编码RNA(LncRNAs)领域。为了接受这一新领域的培训，Jason已经确定了另外两位杰出的合作导师：Howard Chang博士和George Calin博士。未来两年的目标是让Jason接受解决这一新研究领域所需的额外研究培训，以及宝贵的职业指导，为他在一家排名靠前的学术机构成为一名成功的独立调查员做好准备。环境：Jason是Jeffrey Rosen博士实验室的博士后研究员，他在分子和细胞生物学系、丹·L·邓肯癌症中心和莱斯特和苏·史密斯乳房中心的乳房研究项目中担任博士后。BCM是培训学员发展成为成功的独立研究人员所需技能的杰出环境。该学院拥有卓越的教员、中心和最先进的核心设施。BCM位于德克萨斯医疗中心的中心，步行即可到达几家杰出的研究和临床机构，包括M.D.安德森癌症中心、德克萨斯大学休斯顿医学院、莱斯大学和卫理公会医院研究所。这些机构作为额外的科学资源、协作来源和研讨会。研究：基因表达谱已被用于将人类乳腺肿瘤分类为不同的、与临床相关的亚组，包括一种罕见的分子亚型，称为Claudin 很低。与其他亚型的肿瘤相比，Claudin低的肿瘤紧密连接基因和黏附连接基因的表达较低，而上皮向间充质转化(EMT)相关基因的表达较高。我们最近发现，克拉丁低的肿瘤富含功能性的CSCs。已经确定，在人乳腺上皮细胞中诱导EMT可以赋予它们干细胞样的特性。总之，这些证据表明EMT和CSC富含克拉丁的低肿瘤之间存在重要的分子和生物学联系。最近的研究表明，尽管只有不到2%的哺乳动物基因组被编码区占据，但大多数基因组都是转录的。这些转录本被称为非编码RNA(NcRNAs)，因为它们没有蛋白质编码能力。人们一直非常关注一类被称为miRNAs的小ncRNAs在发育和癌症中的作用。相比之下，人们对以lncRNA为代表的绝大多数转录本知之甚少。最近的一个主题是许多lncRNA通过与染色质修饰复合体相互作用来发挥作用，并控制着染色质的结构。虽然LncRNAs在许多生物过程中都涉及到各种功能作用，但只有在相对较少的情况下才能很好地定义这些作用。LncRNA功能的确切机制细节仍然是一个需要探索的谜团。正如可以从lncRNAs在转录调节、表观遗传修饰和发育中的作用可以预料到的那样，越来越多的证据表明在癌症中lncRNAs的错误调控。包括我们在内的几个小组已经表明，与非CSCs相比，乳腺CSCs对放射和化疗的抵抗力更强。我们假设lncRNAs在EMT基因表达程序中发挥关键作用，部分原因是由RNA介导的表观遗传调节导致乳腺癌对传统治疗的抵抗。对导致EMT/CSC表型的分子网络的更好的理解对于确定对抗CSCs的治疗耐药的靶点至关重要，这可能特别与克拉丁低的肿瘤有关。这个项目的目标是利用几个模型系统和大规模功能筛选的策略，首先识别并研究调节Claudin-low乳腺肿瘤EMT/CSC表型的lncRNAs的作用机制。 公共卫生相关性： 完成这项提案的目标将增强我们对调控癌症干细胞(CSCs)的分子机制的理解。这对于设计有选择性地针对这些侵袭性和耐药癌细胞的新治疗方法至关重要。这将使我们能够最终将这些发现转化为临床，以通过长的非编码RNA介导的表观遗传机制来靶向EMT/CSC通路的关键调控，从而使肿瘤对传统疗法敏感。

DESCRIPTION (provided by applicant): Candidate: Dr. Jason Herschkowitz began his research career as a graduate student in the laboratory of Dr. Charles Perou at UNC Chapel Hill. His research focus was on a large-scale genomic comparison of human breast cancer subtypes and genetically engineered mouse mammary tumor models. This study showed that although no single mouse model recapitulated all the expression features of a given human subtype, many of the defining characteristics of the human subtypes were conserved among the mouse models providing insight for their preclinical applications. Jason then moved to the Baylor College of Medicine (BCM) as a postdoctoral fellowship in Dr. Jeffrey Rosen's laboratory. There he has concentrated on studying the claudin-low subtype of breast cancer initially identified in his graduate work. Using a unique mouse model, he has determined that claudin-low tumors are enriched for functional cancer stem cells (CSCs) compared to tumors of other subtypes arising in this model. Jason's graduate training has provided him with an expertise in cancer genomics and mouse models. His postdoctoral work has given him the knowledge and skills involved in stem cell research, mammary gland development, and tumorigenesis. Jason's short-term career goals are to now take what he has learned and apply it to the field of long non-coding RNAs (lncRNAs). In order to receive training in this new area, Jason has identified two additional outstanding co-mentors in Dr. Howard Chang and Dr. George Calin. The goal of the next two years is for Jason to receive the additional research training necessary to tackle this new research area as well as valuable career mentorship to prepare him for a successful career as an independent investigator at a highly ranked academic institution. Environment: Jason is a postdoctoral fellow in the laboratory of Dr. Jeffrey Rosen in the department of Molecular and Cellular Biology, part of the Dan L. Duncan Cancer Center and the Breast Research Program of the Lester and Sue Smith Breast Center. BCM is an outstanding environment for trainees to develop the necessary skills to become successful independent researchers. The college has exceptional faculty, centers, and state of the art core facilities. BCM is located in the heart of the Texas Medical Center and is walking distance to several outstanding research and clinical institutions including M.D. Anderson Cancer Center, UT Houston Medical School, Rice University, and the Methodist Hospital Research Institute. These institutions serve as additional scientific resources, sources of collaboration, and seminars. Research: Gene expression profiling has been used to classify human breast tumors into distinct, clinically- relevant subgroups, including a rare molecular subtype referred to as claudin low. Compared to tumors of other subtypes, claudin-low tumors have lower expression of tight and adherens junction genes, including claudin 3 and E-cadherin, and higher expression of epithelial to mesenchymal transition (EMT) associated genes. We recently found that claudin-low tumors are enriched for functional CSCs. It has been determined that inducing EMT in human mammary epithelial cells endows them with stem cell-like properties. Together these lines of evidence suggest important molecular and biological links between EMT and the CSC-enriched claudin-low tumors. Recent studies suggest that the majority of the genome is transcribed even though less than 2% of the mammalian genome is occupied by coding regions. These transcripts are called non-coding RNAs (ncRNAs) because they have no protein coding capacity. There has been a great deal of focus on the role of a class of small ncRNAs, called miRNAs, in development and cancer. In contrast, much less is known about the vast majority of transcripts represented by lncRNAs. One recent theme is that many lncRNAs function through interactions with chromatin modifying complexes and control chromatin architecture. While a variety of functional roles for lncRNAs have been implicated in many biological processes, only in relatively few cases have these been well defined. The precise mechanistic details of lncRNA function remain a mystery that needs exploration. As might be expected from the roles of lncRNAs in transcriptional regulation, epigenetic modifications, and development, there is increasing evidence of the misregulation of lncRNAs in cancer. Several groups, including ours, have shown that breast CSCs are more resistant to radiation and chemotherapy compared to non-CSCs. We hypothesize lncRNAs play a critical role in an EMT gene expression program governed in part by RNA-mediated epigenetic regulation leading to resistance to conventional therapies in breast cancer. An improved understanding of the molecular networks responsible for the EMT/CSC phenotype is critical for defining targets for combating the therapeutic resistance of CSCs, which may be especially pertinent to claudin-low tumors. The goal of this project, using several model systems and a strategy for large-scale functional screening, is to first identify and then investigate the mechanisms of action of lncRNAs that regulate the EMT/CSC phenotype of claudin-low breast tumors. PUBLIC HEALTH RELEVANCE: Completing the goals of this proposal will enhance our understanding of the molecular mechanisms that regulate cancer stem cells (CSCs). This will be critical for devising new treatments that selectively target these aggressive and therapy-resistant cancer cells. This will enable us to ultimately translate these findings into the clinic in order to sensitize tumors to conventional therapies by targeting critical regulation of EMT/CSC- pathways by long non-coding RNA mediated epigenetic mechanisms.