Characterization of the Multiple Myeloma Cancer Stem Cell and its Niche

描述(由申请人提供)：这项R21干细胞和癌症提案的广泛目标是1)确定MM-CSC的身份和致瘤潜能，以及2)确定MM-CSC和基质之间的N-钙粘素相互作用是否需要维持MM-CSC的增殖停滞。这项工作将为研究调控MM-CSC增殖和分化的信号通路打开大门，一旦鉴定出这些信号通路，就可以设计新的药物来阻止分化诱导因子与MM-CSC之间的相互作用，从而创造第一个能够防止肿瘤起始和复发的MM-CSC靶向治疗药物。理论基础：在过去的十年里，支持癌症干细胞(CSC)理论的强有力的证据一直在稳步积累。除了具有致瘤能力外，CSC还具有正常干细胞的特性，包括静止和自我更新能力。当从微环境接收到增殖信号(S)时，CSC将其程序从静止状态切换到分化和增殖，从而启动肿瘤生长。虽然实体瘤患者可能受益于手术切除他们的恶性生长，希望与耐药肿瘤启动的CSC一起，但手术选择不适用于血液系统恶性肿瘤患者。由于目前使用的治疗方法不能成功地针对CSC，这类患者的复发率很高。因此，确定CSC的哪些特征可以用于治疗是至关重要的。多发性骨髓瘤(MM)是一种无法治愈的骨髓恶性肿瘤。几乎所有多发性骨髓瘤患者都会复发，这表明耐药的多发性骨髓瘤癌症干细胞(MM-CSC)，其身份目前是研究的对象，逃脱了这些治疗。假设：MM-CSCs是在一个特殊的微环境中发现的，它维持这些细胞处于非增殖状态。改变有利于分化的微环境会导致肿瘤的生长。具体目的：目的1：明确MM-CSC的表型。目的2：确定基质与多发性骨髓间充质干细胞之间的N-钙粘素相互作用是否需要维持多发性骨髓间充质干细胞的生态位。总体方法：我们最近开发了一个三维(3-D)体外组织培养模型，概括了人类骨髓的结构和组成。该模型使MM骨髓的增殖期和非增殖期可供进一步分析，在那里可以建立MM干细胞的身份、克隆性、自我更新以及繁殖和致瘤潜力。为了确定MM-CSC的特性并确定其定位，该方案将结合使用3D组织培养系统和异种移植小鼠模型。

DESCRIPTION (provided by applicant): The broad objectives of this R21 Stem Cells and Cancer proposal are to 1) to establish the identity and characterize the tumorigenic potential of the MM-CSC and 2) to determine whether N-cadherin interaction between MM-CSC and stroma is required to maintain the proliferative quiescence of the MM-CSC. This work will open a gateway to study the signaling pathways governing the proliferation and differentiation of the MM-CSC, and once those are identified, new drugs can be designed to prevent the interaction between the differentiation-inducing factors and the MM-CSC, thus creating a first MM-CSC targeted therapeutic agent capable of preventing tumor initiation and relapse. Rationale: Strong evidence in support of the cancer stem cell (CSC) theory has been steadily accumulating over the last decade. In addition to tumorigenic potential, a CSC possesses characteristics of normal stem cells including quiescence and self-renewal potential. Upon receiving proliferation signal(s) from the microenvironment, a CSC switches its program from quiescence to differentiation and proliferation, initiating tumor growth. While patients with solid tumors may benefit from the surgical removal of their malignant outgrowth, hopefully along with drug-resistant tumor-initiating CSC, the surgical option is not available for the patients suffering from hematological malignancies. Such patients have a high rate of relapse due to inability of the currently used therapies to target successfully CSC. Thus, determining which characteristics of the CSC can be therapeutically exploited is of utmost importance. Multiple myeloma (MM) is an incurable malignancy of the bone marrow (BM). Nearly all MM patients relapse indicating that the drug-resistant MM cancer stem cell (MM-CSC), the identity of which is currently a subject of investigation, escapes these therapies. Hypothesis: MM-CSCs are found in a specialized microenvironment niche which maintains these cells in a non-proliferative state. Altering the microenvironment in favor of differentiation leads to tumor growth. Specific Aims: Aim 1: To define the phenotype of the MM-CSC. Aim 2: To determine whether N-cadherin interactions between stroma and MM-CSC are required to maintain the MM-CSC niche. Overall approach: We have recently developed a three-dimensional (3-D) ex vivo tissue culture model recapitulating the architecture and composition of the human BM. This model makes proliferating and non-proliferating compartments of the MM BM accessible for further analysis where the identity, clonality, self-renewal, and generative and tumorigenic potential of MM stem cells can be established. To establish the identity of the MM-CSC and to define its niche this proposal will combine the use of the 3-D tissue culture system with xenograft mouse models.