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

描述（由申请人提供）：套细胞淋巴瘤（MCL）是最耐药的；B细胞，非霍奇金淋巴瘤（NHL-B），目前缺乏足够的治疗，并且在美国的发病率正在增加。由于缺乏有效的动物模型，理解MCL的病理生理学和更好的MCL治疗的实验治疗一直受到阻碍。我们最近构建了第一个转基因MCL模型，该模型密切模拟了最具治疗抗性的MCL形式，即Blastoid变体（MCL- bv）。该模型不仅为MCL-BV的发病机制提供了潜在的见解，而且还具有分层的肿瘤细胞组织，具有类似于肿瘤起始细胞（TIC）的自我更新能力的小而独特的肿瘤细胞亚群。我们MCL- bv模型中的TIC群体也显示出与癌症干细胞（CSC）的相似性，这可能代表了MCL- bv模型中的“起源细胞”，这应该允许在有效的小鼠MCL模型中测试癌症干细胞假设的各种预测。我们的MCL-BV模型是通过IL14 x c-myc单TG小鼠杂交构建的小鼠双转基因（DTG）模型。IL-14是正常B淋巴细胞的一种细胞因子生长因子，在NHL-B中过度表达，在B淋巴细胞谱系中，IL-14可能是一种致癌基因，除了刺激生长外，还表现出重要的B细胞功能特征。DTG小鼠在3-4个月（100%外显率）随机发生类似侵袭性MCL-BV的NHL-B，允许从出生到淋巴瘤发展的小鼠B淋巴样细胞室中分子和基因型改变的序列和明确的病理生理特征实验。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理解MCL- bv个体发生的一个方面，通过识别和表征DTG/MCL- bv模型中可能的“起源细胞”。这些CSC特征包括肿瘤细胞的“自我更新”特征和可移植到免疫缺陷（SCID）小鼠体内。在本提案中，我们将主要关注：(1)表征DTG肿瘤细胞群的分层性质，鉴定SP群体以支持我们的假设，即我们的MCL模型显示肿瘤起始细胞（TIC）具有癌症干细胞（CSC）特征；(2)进一步表征和验证我们的DTG/MCL-BV模型模拟了人类MCL-BV特征的异常细胞周期和组成型生长/生存信号通路激活。我们的研究将探讨在DTG/MCL- bv模型中，假定的MCL/ TIC的csc相关特性如何有助于DTG淋巴瘤的发生、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，包括cyclinD1过表达的异常细胞周期调节和NF-？B和pAKT生长和存活（抗凋亡）信号通路也在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患者，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细胞非霍奇金淋巴瘤，生存预后最差。为什么MCL在临床上具有如此强的侵袭性尚不清楚，这与缺乏合适的动物模型一起阻碍了更有效治疗方法的发展。我们已经开发了MCL囊胚变体（MCL- bv）的基因工程模型（双转基因；DTG），这将为MCL的起源/原因提供线索，并为测试新的MCL药物提供模型，这将在本次拨款申请中开发。

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.