Elucidating the role of microRNAs in the initiation of multiple myeloma

描述（由申请人提供）：多发性骨髓瘤（MM）是一种以骨髓浆细胞集落增殖、溶骨性病变和血清单克隆丙种球蛋白病为特征的癌症。MM是美国第二常见的血液癌症。无论是常规化疗加或不加大剂量治疗/自体干细胞移植，还是新机制的新药治疗，MM患者的中位生存期仅为2~6年。越来越多的证据表明，一个超级家庭的小20~24 nt的非编码RNA称为microRNAs（miRNAs），通过靶向蛋白质编码基因mRNAs的3 'UTR参与细胞的分化、增殖和凋亡，因此参与包括MM在内的癌症的发病机制。我们确定了两个miRNA超家族在人MM和癌症干细胞（CSC）区室中最显著地失调：下调的miR-30和上调的miR-222-221。此外，miR-222-221是MM中上调最多的miRNAs。基于我们的初步数据，miR-222-221靶向CD 40 A的过表达导致MM中的地塞米松抗性和CSC积累。然而，miR-222-221是否会在体内引发MM并促进恶性进展仍有待探索。越来越多的证据还表明，miR-222-221在体外作为致癌基因在多种其他癌症中发挥作用，但miR-222-221在肿瘤中的因果作用是不确定的。 MM的发生尚未得到证实。基于我们在MM中的观察，我们假设该miRNA家族可能有助于MM的起始和进展。我们建议联合收割机结合遗传学和药理学方法来研究miR- 222-221在MM起始中的作用及其成为治疗靶点的潜力。首先，我们将利用临床样本和多种计算方法构建miRNA-mRNA相互作用网络，探讨miR-222-221及其调控网络在MM中的功能意义（目的1）。同时，我们将通过使用两种临床前小鼠模型来功能性表征miR-222-221在MM增殖、凋亡和CSC形成中的作用。一种是条件性转基因小鼠模型Tg：（miR-222-221，AID-Cre小鼠），其将激活miR-222-221在晚期B细胞和浆细胞中的表达。另一种是临床前携带人MM细胞的小鼠模型（Aim 2）。此外，我们还将对microRNA关键下游基因进行功能验证，并评估miR-222-221作为体外和体内治疗靶点的潜力（目的3）。我们的长期目标是了解miRNAs在调节MM启动中的作用，并为这种恶性疾病开发新的候选疗法。

DESCRIPTION (provided by applicant): Multiple myeloma (MM) is a cancer characterized by colonial proliferation of plasma cells in bone marrow, lytic bone lesions, and serum monoclonal gammopathy. MM is the 2th most frequent hematological cancer in the US. The median survival span of MM patients is only 2~6 years, despite treatment either with conventional chemotherapy with or without high-dose therapy/autologous stem cell transplantation, or with new drugs which have novel mechanisms. Increasingly evidence shows that a super family of small (20~24 nt) non-coding RNAs named microRNAs (miRNAs) are involved in cell differentiation, proliferation and apoptosis by targeting 3'UTR of mRNAs of protein coding genes, and therefore involved in cancer pathogenesis, including MM. In our previous work, we identified that two miRNA super families were most significantly deregulated in human MM and cancer stem cells (CSCs) compartment: down-regulated miR-30s, and up-regulated miR-222-221. Moreover, miR-222-221 are the most up-regulated miRNAs in MM. Based on our preliminary data, over- expression of miR-222-221 targets PUMA leads to dexamethasone resistance and CSC accumulation in MM. Nevertheless, it remains unexplored whether miR-222-221 will initiate MM and promote malignant progression in vivo. Accumulating evidence also implicated that miR-222-221 plays a role as oncogene in vitro in a large variety of other cancers, but a causal role for miR-222-221 in the initiation of MM has not been demonstrated. Based on our observation in MM, we hypothesize that this miRNA family may contribute to the initiation and progression of MM. We propose to combine genetic and pharmacological approaches to study the role of miR- 222-221 in MM initiation and its potential to be a therapeutic target. Firstly, we will explore the functioal significance of miR-222-221 and their regulatory network in MM by using the clinical samples and several computational approaches to construct a network of miRNA-mRNA interactions (Aim 1). In parallel, we will functional characterize the role miR-222-221 in MM proliferation, apoptosis and CSC formation by using two preclinical mouse models. One is a conditional transgenic mouse model: Tg:(miR-222-221, AID-Cre mice), which will active miR-222-221 expression in late stage of B cells and plasma cell. Another one is a preclinical human MM cell bearing mouse model (Aim 2). Furthermore, we will functional verify the microRNAs key downstream genes and to evaluate the potential of miR-222-221 as a therapeutic target in vitro and in vivo (Aim 3). Our long-term goal is to understand the role of miRNAs in regulating MM initiation, and to develop new candidate therapies for this malignant disease.