(PQB3) Investigating innate immunosurveillance of oncogene-induced danger signals

描述(申请人提供)：癌症免疫监控是一种潜在的免疫识别和消除前期肿瘤细胞的机制，但对驱动免疫监控的肿瘤细胞衍生危险信号知之甚少。基因工程小鼠模型(GEMM)概括了人类癌症的基本特征，包括肿瘤细胞与其微环境之间的相互作用，并帮助揭示了肿瘤发展的复杂性。我们以前已经使用GEMM来确定肺腺癌和肉瘤发生之间的异同。肌肉细胞表达致癌的KrasG12D激活了涉及p19(Arf)和p53的遗传电路，从而促进停滞和阻止肿瘤的发展。相比之下，肺癌通过在表观遗传学上沉默p19(Arf)来绕过这一遗传回路。在晚期肿瘤细胞中，P53的下游信号也会触发NK和其他天然免疫细胞的停滞和中介消除。KrasG12D受阻的肌肉细胞的命运尚不清楚，但免疫监控和先天免疫细胞的消除可能会降低这些肿瘤前细胞获得额外基因改变并发展为肉瘤的机会。在本申请的目的1中，我们将在一个小鼠模型中直接研究先天免疫细胞在检测和清除肿瘤前细胞中的作用，在该模型中，控制致癌K-RasG12D初始获得的事件独立于控制P53缺失的事件(从停滞状态释放所需)。此外，我们还将 检测NK细胞是否通过表达激活和抑制配体来增强和/或抑制清除。KrasG12D在P53缺陷性肉瘤和肺腺癌中表达的比较为研究肿瘤发生的早期事件如何决定体内抗肿瘤T细胞反应是否具有保护性提供了一个强大的平台。尽管肿瘤在相同的小鼠中发生，具有相同的启动基因改变，表达相同的肿瘤抗原，并引发来自相同群体的初始T细胞的反应，但表达抗原的肺腺癌在小鼠中发生，而表达抗原的肉瘤不发生。在目标2中，我们将比较肉瘤和肺腺癌的早期先天免疫反应，并确定环境和细胞对转化的内在反应如何有助于先天激活和抗肿瘤T细胞反应。在目标3中，我们将确定免疫细胞对肿瘤前期和完全转化的肿瘤细胞的存在产生警觉的机制，以及敲除危险信号是否可以帮助前期肿瘤颠覆免疫监视机制并在体内生长。这些目的将加强我们对分子和细胞事件的理解，这些事件在恶性转化的最早阶段调节免疫监视，并帮助我们理解为什么某些类型的肿瘤因此更具免疫原性。

DESCRIPTION (provided by applicant): Cancer immunosurveillance is a potential mechanism for immune recognition and elimination of pre-emergent tumor cells, but little is known about the tumor cell-derived danger signals that drive immunosurveillance. Genetically engineered mouse models (GEMMs) recapitulate cardinal features of human cancers, including interactions between tumor cells and their microenvironment, and have helped uncover complexities underlying tumor development. We have previously used GEMMs to identify similarities and differences between lung adenocarcinoma and sarcoma development. Expression of oncogenic KrasG12D by muscle cells activates a genetic circuit involving p19 (Arf) and p53 that promotes arrest and stops tumor development. By contrast, lung tumors bypass this genetic circuit by epigenetically silencing p19 (Arf). In advanced tumor cells, signals down-stream of p53 also trigger arrest and mediate elimination by NK and other innate immune cells. The fate of KrasG12D-arrested muscle cells is unclear, but immunosurveillance and elimination by innate immune cells could reduce the chances these pre-neoplastic cells acquire additional genetic alterations and develop into sarcomas. In Aim 1 of this application, we will directly investigate the role of innate immune cells in detecting and clearing pre-neoplastic cells in a mouse model in which the events controlling the initial acquisition of oncogenic K-rasG12D are independent of those controlling p53 deletion (required for release from an arrested state). Additionally, we will test whether NK cells can augment and/or inhibit clearance by expressing activating and inhibitory ligands in these lesions. The comparison of KrasG12D expressing p53-deficient sarcomas and lung adenocarcinomas provides a powerful platform for investigating how early events in tumorigenesis determine whether anti-tumor T cell responses are protective in vivo. Despite tumor development in identical mice, with identical initiating genetic alterations, expressing identical tumor antigens, and eliciting responses from identical populations of naive T cells, antigen-expressing lung adenocarcinomas develop in mice while antigen- expressing sarcomas do not. In Aim 2, we will compare early innate immune responses to sarcomas and lung adenocarcinomas and determine how environmental and cell-intrinsic responses to transformation contribute to innate activation and anti-tumor T cell responses. In Aim 3, we will identify the mechanisms by which immune cells become alerted to the presence of pre-neoplastic and fully transformed tumor cells and whether knockdown of danger signals can help pre-emergent tumors subvert immunosurveillance mechanisms and grow in vivo. These Aims will strengthen our understanding of the molecular and cellular events that regulate immunosurveillance at the earliest stages of malignant transformation and help us to understand why certain tumor types are more immunogenic as a result.