Role of microRNAs in malignant progression

描述（由申请人提供）：越来越明显的是，癌症发病机制可能涉及称为microRNA的小的非编码RNA超家族。虽然许多microRNA的致癌或肿瘤抑制功能已被表征，但microRNA在介导转移中所起的作用最近才由我们实验室和其他几个小组的工作解决。我目前是生命科学研究基金会博士后研究员，近期目标是在怀特黑德生物医学研究所与鲍勃温伯格博士一起完成额外的1-2年指导研究。在我最初的筛选中，我确定了三种在人类乳腺癌细胞系中最显著上调的microRNA：miR-155，miR-9和miR-10 b。随后，我鉴定了miR-10 b作为Twist调节的microRNA，其在转移性癌细胞以及来自患者的转移性乳腺肿瘤中高度表达。这种microRNA抑制HOXD 10蛋白的合成，允许促转移基因产物RhoC的表达。重要的是，miR-10 b在其他非转移性乳腺癌细胞中的过表达使它们能够在体内侵袭和转移。这些发现代表了microRNA过表达有助于转移发展的第一个功能性证据。由于靶向miR-10 b是否会阻止恶性进展仍未探索，我现在提出将联合收割机遗传学和药理学方法结合来研究miR-10 b在发育和乳腺癌转移中的功能丧失作用。此外，基于先前未描述的观察结果，即原发性乳腺肿瘤中的miR-10 b过表达导致在组织学可检测的肺微转移的证据之前肺巨噬细胞积聚，我将探索miR-10 b在转移进展中的细胞非自主作用。与此同时，我将描述第二个在我的初步筛选中脱颖而出的候选microRNA，miR-9，在上皮-间充质转化，血管生成和转移中的作用，因为miR-9是唯一预测靶向E-cadherin的microRNA，E-cadherin是一种主要的粘附分子，其丢失与肿瘤侵袭和转移密切相关。长期目标是了解microRNA在调节转移中的作用，并开发恶性疾病的新候选疗法。 相关性：这项研究不仅阐明了肿瘤转移的遗传和分子基础，而且对乳腺癌的治疗也有意义。这将是第一个关于抑制特定microRNA是否可以预防转移的概念验证研究。对转移介导的microRNA的细胞非自主作用的研究可能导致发现具有治疗潜力的内分泌蛋白。

DESCRIPTION (provided by applicant): It has become increasingly evident that cancer pathogenesis can involve a superfamily of small non-coding RNAs named microRNAs. While the oncogenic or tumor-suppressing functions of a number of microRNAs have been characterized, the role played by microRNAs in mediating metastasis was addressed only recently by work from our laboratory and several other groups. I am currently a Life Sciences Research Foundation Postdoctoral Fellow with the immediate goal of completing additional 1-2 years of mentored research with Dr. Bob Weinberg at the Whitehead Institute for Biomedical Research. In my initial screening, I identified three microRNAs that are most significantly upregulated in human breast cancer cell lines: miR-155, miR-9, and miR-l0b. Subsequently, I identified miR-l0b as a Twist-regulated microRNA that is highly expressed in metastatic cancer cells as well as in metastatic breast tumors from patients. This microRNA inhibits synthesis of the HOXD10 protein, permitting the expression of the pro-metastatic gene product, RhoC. Importantly, overexpression of miR-l0b in otherwise-non- metastatic breast cancer cells enables them to invade and metastasize in vivo. These findings represent the first functional evidence that overexpression of a microRNA can contribute to the development of metastasis. Since it remains unexplored whether targeting miR-l0b will inhibitmalignant progression, I now propose to combine genetic and pharmacological approaches to study miR-l0b loss-of-function effects in development and in breast cancer metastasis. Moreover, based on a previously undescribed observation that miR-l0b overexpression in the primary mammary tumor leads to lung macrophage accumulation prior to evidence of histologically detectable pulmonary micrometastases, I will explore the cell non-autonomous effects of miR-l0b in metastatic progression. In parallel, I will characterize the role of a second candidate microRNA that stood out in my initial screen, miR-9, in epithelial-mesenchymal transitions, angiogenesis, and metastasis, given that miR-9 is the only microRNA that is predicted to target E-cadherin, a major adhesion molecule whose loss is strongly implicatedin tumor invasion and metastasis. The long-term goal is to understand the role of microRNAs in regulating metastasis, and to develop new candidatetherapies for malignant diseases. RELEVANCE: Not only does this study illuminate the genetic and molecular basis of tumor metastasis, but it also has implications for breast cancer treatment. This will be the first proof-of-concept study of whether inhibiting a specific microRNA can prevent metastasis. Investigation of the cell non-autonomous effects of metastasis- mediating microRNAs may lead to discovery of endocrine proteins that have therapeutic potentials.