Aged tissue environments as drivers of oncogenic adaptation in hematopoiesis

大多数癌症的风险，包括白血病，随着年龄的增长呈指数级增加， 超过90%的癌症发生在50岁以后。这种联系主要被归因于 致癌基因突变在一生中逐渐积累。我们认为， 突变的贡献，虽然是必要的，但不足以解释衰老在 白血病和其他癌症的发展。就像物种进化是由 在种群中选择适应性表型的环境变化，我们认为 我们的组织在老年时发生的变化是肿瘤发生的重要因素。在……里面 特别是，老年人骨髓中的炎症增加，这有助于损害 造血术。我们的中心假设是，与年龄相关的炎症增加是 对于加强对致癌基因突变的选择至关重要，而且抑制炎症可以 降低相关白血病的风险。我们之前已经使用鼠标模型来展示 衰老炎症性骨髓微环境降低B细胞适合性 祖细胞，促进对特定适应性致癌事件的选择，导致 白血病的发生。在这里，我们将探索老年微环境变化如何促进 未成熟造血干细胞和顶端早期祖细胞(HSPC)池中的致癌作用 在造血系统中的地位。我们认为C/EBPα和Myc活动是 老年骨髓微环境中致癌基因的选择 平衡HSPC差异化和自我更新。因此，我们将制定干预措施，以减少 微环境扰动解除对C/EBP、α和Myc的调控并导致肿瘤发生 年纪大了。为了验证我们的假设，我们将追求两个目标：1)确定衰老和 炎症驱动HSPC室的致癌适应和2)识别机制 在HSPC池中，随着年龄的增长，潜在的肿瘤发生增加。 通过确定微环境变化是否以及如何影响HSPC适合性和 因此，老年的致癌适应，这些结果可能为联系提供新的解释 衰老和白血病风险之间的关系。总之，我们提议的研究可以为以下问题提供答案 基本问题：为什么随着年龄的增长，我们会患上更多的白血病？为什么特定的致癌因素 在老年人的骨髓中选择突变？我们能改变与衰老相关的积极因素吗 选择致癌事件，从而降低白血病风险？这些研究还可以确定 通过操作降低老年血液系统恶性肿瘤风险的干预措施 在骨髓微环境中促进肿瘤发生的炎性因子。

The risk of most cancers, including leukemias, increases exponentially as we age, with over 90% of cancers occurring after the age of 50. This association has been primarily ascribed to the gradual accumulation of oncogenic mutations throughout life. We contend that the contribution of mutations, while necessary, is not sufficient to explain the role of aging in the development of leukemias and other cancers. Just as species evolution has been driven by environmental changes that select for adaptive phenotypes in populations, we propose that the changes in our tissues occurring in old age are substantial contributors to oncogenesis. In particular, inflammation increases in the bone marrow of the elderly, which contributes to impaired hematopoiesis. Our central hypothesis is that aging-dependent increases in inflammation are critical for enhancing selection for oncogenic mutations, and that dampening inflammation can reduce the risk of the associated leukemias. We previously have used mouse models to show that the aged and inflammatory bone marrow microenvironment reduces the fitness of B-cell progenitors, promoting selection for particular adaptive oncogenic events, leading to increased leukemogenesis. Here, we will explore how microenvironmental alterations in old age promote oncogenesis in immature hematopoietic stem and early progenitor cell (HSPC) pools at the apex of the hematopoietic hierarchy. We propose that C/EBPα and Myc activities are key hubs for oncogenic selection in aged bone marrow microenvironments due to their critical roles in balancing HSPC differentiation and self-renewal. Thus, we will develop interventions to reduce microenvironmental perturbations that deregulate C/EBPα and Myc and lead to oncogenesis in old age. To test our hypothesis, we will pursue two aims: 1) Determine whether aging and inflammation drive oncogenic adaptation in the HSPC compartment and 2) Identify mechanisms underlying increased oncogenesis with aging in HSPC pools. By determining whether and how microenvironmental changes impact HSPC fitness and thus oncogenic adaptation in old age, these results could provide a new explanation for links between aging and leukemia risk. In all, our proposed studies could provide answers for fundamental questions: Why do we get more leukemias as we age? Why are particular oncogenic mutations selected for in the bone marrow of the elderly? Can we alter aging-associated positive selection for oncogenic events and thus reduce leukemia risk? These studies could also identify interventions that reduce the risk of hematopoietic malignancies of old age by manipulating inflammatory factors that promote oncogenesis in the bone marrow microenvironment.