Combining modeling and experiments to study the evolution of cells with altered ploidy

项目摘要 非整倍体是癌细胞的普遍特征，非整倍体的积累被认为是经常发生的 通过四倍体(基因组加倍)作为中间步骤。这一想法是基于观察到的 近40%的肿瘤可能在克隆进化过程中经历了全基因组复制，即 四倍体可以缓冲染色体不稳定性(CIN)，四倍体(4N)，但不是二倍体(2N)， 乳腺上皮细胞可诱发裸鼠皮下肿瘤。一个被广泛接受的模型表明 在四倍化过程中通常出现的额外的中心体负责进行中的染色体 有丝分裂过程中的错误分离导致非整倍体和CIN的积累。一种可能的选择性 非整倍体带来的优势反过来又会促进肿瘤的发生。对此模型的支持来自 在人类肿瘤中观察到非整倍体和多余的中心体这一事实，以及 额外的中心体可以在动物模型中促进肿瘤的发生。然而，最近的报告显示， 在标准培养条件下保存的细胞会自发失去在 这种中心体的丢失可以发生在很短的时间内(大约两周)。这个 认为在体内发生的情况与在标准组织培养中观察到的情况之间的差异 条件表明体内的生态位(例如，肿瘤微环境中的各种因素) 可以施加特定的选择压力，从而影响4N细胞的进化，从而产生 四倍体。这一假设将通过实验诱导四倍体，然后结合 用多学科方法研究改变的倍性/中心体数目与 三个具体研究对象中的微环境。第一个目标将决定物理效应-- 化学微环境对4N细胞进化的影响，并将识别特定的、与生理相关的、 产生不同于进化的细胞群体的微环境的物理化学性质 在标准的文化条件下出现。第二个目标将确定如何与基质细胞进行沟通 影响4N上皮细胞的进化，并具体评估信号分子和细胞- 在塑造倍性改变细胞进化过程中的细胞物理相互作用。第三个目标将确定关键 体内驱动4N细胞进化的过程。这将通过将新形成的4N细胞注射到 小鼠模型，然后描述进化的肿瘤衍生细胞群体。一首基于颂歌的诗 将在每个目标中使用数学模型来捕捉细胞亚群的进化动态 确定倍体和中心体数量，并精确定位事件、细胞过程和微环境 驱动不同的、依赖于背景的、进化的结果的因素。这些研究的发现 不仅将拓宽目前的知识，而且还将为未来发现潜力奠定基础 癌症治疗的分子靶点和/或新的微环境操作。

Project Summary Aneuploidy is a ubiquitous feature of cancer cells, and accumulation of aneuploidy is believed to often happen via tetraploidization (genome doubling) as an intermediate step. This idea is based on the observations that nearly 40% of all tumors have likely undergone whole genome duplication during their clonal evolution, that tetraploidy was shown to buffer chromosomal instability (CIN), and that tetraploid (4N), but not diploid (2N), mammary epithelial cells could induce subcutaneous tumors in nude mice. A widely accepted model suggests that the extra centrosomes commonly arising during tetraploidization are responsible for ongoing chromosome missegregation during mitosis leading to the accumulation of aneuploidy and CIN. A possible selective advantage conferred by aneuploidy would, in turn, promote tumorigenesis. Support for this model comes from the fact that both aneuploidy and supernumerary centrosomes have been observed in human tumors and that extra centrosomes can promote tumorigenesis in animal models. However, recent reports have shown that cells kept in standard culture conditions spontaneously lose extra centrosomes acquired during tetraploidization, and that this centrosome loss can occur over a very short time period (about two weeks). The discrepancies between what is believed to happen in vivo and what is observed in standard tissue culture conditions suggests that the in vivo ecological niche (e.g., various factors within the tumor microenvironment) can impose specific selective pressures that influence the evolution of 4N cells, and thus the consequences of tetraploidization. This hypothesis will be tested by experimentally inducing tetraploidy and then combining a multi-disciplinary approach to study the interplay between altered ploidy/centrosome number and the microenvironment in three specific research aims. The first aim will determine the effects of the physico- chemical microenvironment on the evolution of 4N cells and will identify specific, physiologically relevant, physico-chemical properties of the microenvironment that produce an evolved cell population unlike the one emerging in standard culture conditions. The second aim will establish how communication with stromal cells influences the evolution of 4N epithelial cells and specifically assess the role of signaling molecules and cell- cell physical interactions in shaping the evolution of cells with altered ploidy. The third aim will identify the key processes driving the evolution of 4N cells in vivo. This will be achieved by injecting newly formed 4N cells in mouse models and then characterizing the evolved, tumor-derived cell population. An ODE-based mathematical model will be used in each aim to capture the evolution dynamics of subpopulations of cells with defined ploidies and centrosome numbers and pinpoint the events, cellular processes, and microenvironmental factors that drive the differential, context-dependent, evolutionary outcomes. The findings from these studies will not only broaden the current knowledge, but also set the stage for future identification of potential molecular targets and/or novel microenvironment manipulations for cancer therapy.