Elucidating the role of microRNAs in the initiation of multiple myeloma

描述(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性伽马病为特征的癌症。多发性骨髓瘤在美国最常见的血液病中排名第二。MM患者的中位生存期仅为2~6年，无论采用常规化疗加或不加大剂量治疗/自体干细胞移植，或采用具有新机制的新药治疗。越来越多的证据表明，一个小的(20~24个核苷酸)非编码RNA超家族microRNAs(MiRNAs)通过靶向蛋白编码基因mRNAs的3‘端非编码区参与细胞的分化、增殖和凋亡，从而参与包括MM在内的肿瘤发病机制。在我们之前的工作中，我们发现有两个miRNA超家族在人类多发性骨髓瘤和肿瘤干细胞(CSCs)中表达最显著的下调：下调的miR-30s和上调的miR-222-221。此外，miR-222-221是MM中上调最多的miRNAs，根据我们的初步数据，miR-222-221靶标PUMA的过度表达导致MM对地塞米松的耐药和CSC的积聚。然而，目前尚不清楚miR-222-221是否会启动MM并促进体内的恶性进展。越来越多的证据还表明，miR-222-221在体外作为癌基因在许多其他癌症中发挥作用，但miR-222-221在 多发性硬化症的启动尚未得到证实。基于我们在MM中的观察，我们假设这个miRNA家族可能在MM的发生和发展中起作用。我们建议结合遗传学和药理学的方法来研究miR-222-221在MM启动中的作用及其作为治疗靶点的可能性。首先，我们将通过临床样本和几种构建miRNA-mRNA相互作用网络的计算方法来探索miR-222-221及其调控网络在多发性骨髓瘤中的功能意义(目标1)。同时，我们将使用两个临床前小鼠模型来研究miR-222-221在多发性骨髓瘤增殖、凋亡和CSC形成中的作用。一种是条件转基因小鼠模型：Tg：(MIR-222-221，AID-CRE小鼠)，它将激活B细胞和浆细胞晚期miR-222-221的表达。另一种是临床前人MM细胞荷小鼠模型(Aim 2)。此外，我们将验证microRNAs关键下游基因的功能，并评估miR-222-221作为体外和体内治疗靶点的潜力(目标3)。我们的长期目标是了解miRNAs在调节MM启动中的作用，并开发这种恶性疾病的新候选疗法。

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.