Murine Models for Mantle Cell Lymphoma: The role of tumor initiating cells (TIC)

描述(申请人提供)：套细胞淋巴瘤(MCL)是最耐药的；B细胞非霍奇金淋巴瘤(NHL-B)，目前缺乏适当的治疗，在美国的发病率正在上升。由于缺乏有效的动物模型，对MCL的病理生理学和更好的MCL治疗的实验疗法的理解一直受到阻碍。我们最近构建了第一个转基因的MCL模型，它与最具治疗耐药性的MCL形式--芽囊样变异体(MCL-BV)非常相似。该模型不仅对MCL-BV的发病机制提供了潜在的见解，而且具有层次化的肿瘤细胞组织，具有类似于肿瘤起始细胞(TIC)的自我更新能力，具有少量但独特的肿瘤细胞亚群。我们的MCL-BV模型中的TIC群体也显示出与癌症干细胞(CSC)的相似之处，后者可能代表该MCL-BV模型中的“起源细胞”，这应该允许在有效的小鼠MCL模型中检验癌症干细胞假说的各种预测。我们的MCL-BV模型是通过与IL14×c-myc单转基因小鼠杂交而构建的小鼠双转基因(DTG)模型。IL-14是一种正常B淋巴细胞的细胞因子生长因子，在NHL-B中高表达，在B淋巴细胞谱系中可能作为癌基因发挥作用，除了生长刺激外，还显示出重要的B细胞功能特征。DTG小鼠在3-4个月内随机发展为类似侵袭性MCL-BV的NHL-B(100%外显性)，允许通过实验对小鼠B淋巴细胞室从出生到淋巴瘤发展过程中的分子和基因型别变化进行连续和明确的病理生理学表征。DTG MCL-BV模型为MCL提供了多种有趣的潜在见解，但我们在R21提案中的研究将集中在通过识别和表征DTG/MCL-BV模型中可能的“起源细胞”来理解MCL-BV个体发育的一个方面。这些CSC特性包括肿瘤细胞的自我更新特性和移植到免疫缺陷(SCID)小鼠体内的能力。在这项建议中，我们将主要集中在：(1)表征DTG肿瘤细胞群体的层次性，鉴定SP群体以支持我们的假设，即我们的MCL模型显示具有肿瘤干细胞(CSC)特征的肿瘤起始细胞(TIC)；以及(2)进一步表征和验证我们的DTG/MCL-BV模型模拟了异常的细胞周期和结构性生长/生存信号通路激活，这是人类MCL-BV的特征。我们的研究将探索DTG/MCL-BV模型中假定的MCL/TIC的CSC相关特性如何有助于DTG淋巴瘤的启动、肿瘤维持和可能的复发。我们还将研究众所周知的人类MCL特征是否也在DTG/TIC肿瘤细胞和/或其他DTG肿瘤亚群中被激活，这可能解释了MCL，特别是MCL-BV患者的临床治疗耐药。公共卫生相关性：套细胞淋巴瘤(MCL)是临床上最难治疗的B细胞性非霍奇金淋巴瘤，生存预后最差。MCL在临床上如此具有侵袭性的原因尚不清楚，这与缺乏合适的动物模型一起阻碍了更有效的治疗方法的开发。我们已经开发了一种MCL(MCL-BV)囊胚样变体的基因工程模型(双重转基因；DTG)，它将提供MCL的起源/原因的线索，以及一种测试MCL新药的模型，该模型将在本次拨款提案中开发。

DESCRIPTION (provided by applicant): Mantle cell lymphoma (MCL) is the most therapy-resistant; B cell, non-Hodgkin's lymphoma (NHL-B) that currently lacks adequate therapy, and is increasing in incidence in the USA. Understanding the patho- physiology of MCL and experimental therapeutics for better MCL therapy has been hampered by the lack of a valid animal model. We have recently constructed the first transgenic MCL model that closely simulates the most therapy-resistant form of MCL, the Blastoid variant (MCL-BV). This model not only provides potential insights into the pathogenesis of MCL-BV, but also has a hierarchical tumor cell organization, with a small but distinct tumor cell subpopulation with self-renewal capabilities that resemble tumor initiating cells (TIC). The TIC population in our MCL-BV model also shows similarities to Cancer Stem Cells (CSC) that may represent the "cell of origin" in this MCL-BV model that should allow for testing various predictions of the Cancer Stem cell hypothesis, in a valid murine MCL model. Our MCL-BV model is a murine double transgenic (DTG) that was constructed by crossing IL14 x c-myc single TG mice. IL-14, a cytokine growth factor for normal B-lymphocytes, is over-expressed in NHL-B, where it may function as an oncogene in the B lymphocytic lineage, showing important B cell functional characteristics in addition to growth stimulation. DTG mice stochastically develop NHL-B resembling aggressive MCL-BV by 3-4 months (100% penetrance), allowing for sequential and defined patho-physiologic characterization of molecular and genotypic alterations in the murine B lymphoid cell compartment experimentally, from birth to lymphoma development. The DTG MCL-BV model provides multiple interesting potential insights into MCL, but our studies in this R21 proposal will focus on understanding one aspect in MCL-BV ontogeny, by identifying and characterizing a possible "cell of origin" in DTG/MCL-BV model. These CSC characteristics include tumor cell "self-renewal" characteristics and transplantabilty into immune-deficient (SCID) mice. In this proposal, we will focus primarily on: (1) characterizing the hierarchical nature of DTG tumor cell populations, identification of SP populations to support our hypothesis that our MCL model displays Tumor Initiating Cells (TIC) with Cancer Stem Cell (CSC) characteristics; and (2) further characterizing and validating that our DTG/MCL-BV model simulates anomalous cell cycle and constitutive growth/survival signaling pathway activation, characteristic of human MCL-BV. Our studies will explore how CSC-associated properties of putative MCL/ TIC in the DTG/MCL-BV model, contributes to the initiation, tumor maintenance, and possibly recurrence of the DTG lymphoma. We will also examine whether well-known human MCL characteristics, involving abnormal cell cycle regulation with cyclinD1 over-expression, and the constitutive activation of the NF-?B and pAKT growth and survival (anti-apoptotic) signaling pathways, are also activated in DTG/TIC tumor cells and/or other DTG tumor sub- populations, that may account for the clinical therapeutic resistance seen in patients with MCL, and particularly MCL-BV. PUBLIC HEALTH RELEVANCE: Mantle cell lymphoma (MCL) is the most difficult B cell Non-Hodgkin lymphoma to treat clinically, with the worst survival prognosis. Why MCL is so clinically aggressive is not known, which along with the lack of a suitable animal model has hampered development of more effective therapies. We have developed a genetically engineered model (double transgenic; DTG) of the blastoid variant of MCL (MCL-BV) that will provide both clues to the origin/causes of MCL as well as a model to test new MCL drugs, which will be developed in this grant proposal.