The Lung Tumor Microenvironment: Role of Resident Pulmonary Vascular Progenitor Cells in Cancer Progression and Metastasis

摘要 肺癌仍然是全球癌症相关死亡的主要原因。虽然靶向治疗针对 致癌驱动因素和免疫治疗方法在降低发病率和耐药性方面已显示出希望 靶向治疗常常导致疾病复发和进展。另外，只有相对较小的一部分 未经选择的非小细胞肺癌（NSCLC）患者对单一免疫疗法有反应。因此，小说 迫切需要治疗方法。开发新的治疗策略需要更好的 了解肿瘤微环境中癌细胞和细胞之间复杂的相互作用 （TME）。 TME 是多种细胞类型的复杂生态位，包括先天性和适应性免疫细胞 免疫系统、癌症相关成纤维细胞、血管细胞和细胞外基质 (ECM)。定义 TME 细胞调节癌症进展的关键细胞类型和机制仍然是一个挑战。 最近出现了大量与招募免疫细胞相关的研究。另外，虽然肿瘤 血管生成是癌症的一个标志，抗血管生成疗法在治疗肺癌方面取得的成功有限 癌症，因此需要更好地了解脉管系统如何促进疾病进展。 最后，虽然癌症干细胞在癌症进展中的作用已得到充分证实，但基质细胞的作用 祖细胞/干细胞对 TME 和癌症进展和转移的贡献是完全 正在研究的研究领域。我们通过使用命运绘图系统进行的偶然观察 在血管疾病的情况下追踪血管平滑肌细胞（SMC）表明，成熟的 SMC 迁移到血管外外膜层并通过基因重编程形成亚群 称为 AdvSca1-SM 细胞的常驻外膜祖细胞。 AdvSca1-SM 细胞是精选的亚群 具有多种命运决定的真实血管祖细胞。 AdvSca1-SM 细胞存在于多个 血管床（例如主动脉、颈动脉和股动脉，以及肺动脉和冠状动脉脉管系统）。 重编程依赖于转录因子 Klf4 的 SMC 诱导，AdvSca1-SM 细胞是 对血管壁功能障碍做出反应的主要细胞类型，这取决于 Klf4 的丢失。我们最近的 研究结果表明，肺 AdvSca1-SM 细胞数量增加，采用肌成纤维细胞表型，并且 肺癌进展和转移的主要贡献者。我们在此提出，癌细胞介导的 AdvSca1-SM 细胞的激活导致其分化为促进肿瘤生长的 TME 必需细胞 进展和转移。消融会减弱，但 Klf4 表达的丧失会加剧肿瘤生长， 转移。两个目标将检验我们的假设。 Aim One 将使用创新的体内命运图谱和体外命运图谱 条件培养基方法定义 AdvSca1-SM 细胞的命运以及癌细胞在 AdvSca1-中的作用 SM 细胞在肺癌进展和转移中的激活。目标二将定义以下角色： AdvSca1-SM 细胞消融或 AdvSca1-SM 特异性删除 Klf4 对肺癌进展和转移的影响。

ABSTRACT Lung cancer remains the leading cause of cancer-related deaths worldwide. While targeted therapies against oncogenic drivers and immunotherapy approaches have shown promise in reducing the incidence, resistance to targeted therapies often leads to relapse and progression of disease. In addition, only a relatively small portion of unselected non-small cell lung cancer (NSCLC) patients respond to mono-immunotherapy. Therefore, novel therapeutic approaches are urgently needed. Developing new therapeutic strategies requires a better understanding of the complex interactions between cancer cells and cells within the tumor microenvironment (TME). The TME is a complex niche of multiple cell types, including immune cells of the innate and adaptive immune system, cancer-associated fibroblasts, vascular cells, and extracellular matrix (ECM). Defining the critical cell types and mechanisms whereby cells of the TME regulate cancer progression remains a challenge. Recently an abundance of studies related to recruited immune cells have emerged. Also, while tumor angiogenesis is a hallmark of cancer, anti-angiogenic therapy has had limited success for the treatment of lung cancer, and thus a better understanding of how the vasculature contributes to disease progression is required. Finally, while the role of cancer stem cells to cancer progression has been well established, the role of stromal progenitor/stem cells contributing to the TME and cancer progression and metastasis is a completely understudied area of research. Serendipitous observations made by us through the use of fate-mapping systems to track vascular smooth muscle cells (SMCs) in the setting of vascular disease demonstrated that mature SMCs migrate into the outer adventitial layer of the blood vessel and are genetically reprogrammed into a subpopulation of resident adventitial progenitor cells termed AdvSca1-SM cells. AdvSca1-SM cells are a select subpopulation of authentic vascular progenitor cells that exhibit multiple fate decisions. AdvSca1-SM cells reside in multiple vascular beds (e.g. aorta, carotid and femoral arteries, and the pulmonary and coronary arterial vasculature). Reprogramming is dependent on SMC induction of the transcription factor, Klf4, and AdvSca1-SM cells are the predominant cell type responding to vessel wall dysfunction, which is dependent on loss of Klf4. Our recent findings demonstrate that lung AdvSca1-SM cells expand in number, adopt a myofibroblast phenotype, and are major contributors to lung cancer progression and metastasis. We propose here that cancer cell-mediated activation of AdvSca1-SM cells results in their differentiation into essential cells of the TME that promote tumor progression and metastasis. Ablation will blunt, but loss of Klf4 expression will exacerbate tumor growth and metastasis. Two Aims will test our hypotheses. Aim One will use innovative in vivo fate mapping and in vitro conditioned media approaches to define the fate of AdvSca1-SM cells and the role of cancer cells in AdvSca1- SM cell activation in the setting of lung cancer progression and metastasis. Aim Two will define the role of AdvSca1-SM cell ablation or AdvSca1-SM-specific deletion of Klf4 on lung cancer progression and metastasis.