Mechanisms of Disseminated Tumor Cell Dormancy

总结项目2：大多数癌症患者将死于源自播散性肿瘤的转移 细胞(DCs)，治疗后数年甚至数十年。这表明DTC在休眠状态下存活， 非增殖性状态。然而，由于对DTC的生物学了解甚少，因此询问BASIC是至关重要的 进一步发展翻译方法的机械性问题。我们的目标是确定这些机制 通过将强大的活体模型与新的成像和纳米设备技术相结合， 这种合作。该联盟为研究休眠和解决三个问题提供了前所未有的协同作用 RFA的重点领域：1)肿瘤休眠、休眠细胞的激活和肿瘤微环境 (SAI)，和对癌症治疗的休眠(SA2)；2)成像肿瘤微环境 肿瘤转移、休眠(SAI)以及对治疗的反应(SA2)和3)特征 肿瘤微环境细胞外基质(ECM)与肿瘤细胞功能的相关性 间质相互作用(即小生境)决定转移细胞的命运(SA2)。我们假设至少有两个 场景会影响DTC休眠。情景1：来自浸润性癌症的DTC激活应激信号 对限制生长的目标器官微环境诱导休眠的反应。情景2：治疗 和/或微环境应激条件(例如，缺氧)作用于携带 “休眠签名”使新的DTC进入休眠状态。基于这两种情况，我们建议 1)分离DTC并确定驱动DTC休眠的微环境特定基因程序(场景1) 2)确定原发肿瘤“应激微环境”是否触发DTCs的长期休眠 (场景2)。这两个AIMS的发现都将使用存档的人类原发和转移肿瘤进行验证。 使用人鳞状细胞癌(HEp3)和小鼠乳腺癌模型(MMTV-Neu)，我们发现Low ERK1/2(有丝分裂)和高P38A/p(胁迫)信号激活了DTCs的休眠。肿瘤细胞 自发扩散至肺、淋巴结(LN)和骨髓(BM)。短期休眠 在肺DCs扩张之前的一段时间(2-3周)。然而，BM DTC持续处于休眠状态 (场景1)。全身性抑制P38A/p可消除肺DTCs的短期休眠 促进生长，即使在脾、肝和骨髓等从未观察到的地方也是如此。因此，DTC可能会保留 生长受限地点的隐蔽和休眠(情景1)。我们还鉴定了一种特定的基因表达 程序(签名)在休眠的HEp3细胞中，存在于来自BM DTC的细胞系中。重要的是 携带这种休眠基因特征的乳腺原发肿瘤患者无转移。 比签名的负数更长的期限(情景2)。我们还发现，接触亚致死物质 剂量的辐射或氧化应激使存活的细胞处于休眠状态(场景2)。这些 初步数据进一步支持了我们在理解我们的情景方面取得的重要进展 建议在我们的具体目标上进行探索。

SUMMARY PROJECT 2: Majority of cancer patients will die of metastases originating from disseminated tumor cells (DTCs), years or even decades after treatment. This suggests that DTCs survive in a dormant, non-proliferative state. However, because the biology of DTCs is poorly understood it is critical to ask basic mechanistic questions to further develop translational approaches. Our goal is to identify these mechanisms by combining powerful In vivo models and novel imaging and nano-device technologies available through this collaboration. This consortium provides unprecedented synergy to study dormancy and address three emphasis areas of this RFA: 1) tumor dormancy, activation of dormant cells and the tumor microenvironment (SAI), and dormancy in response to cancer treatment (SA2); 2) imaging the tumor microenvironment during tumor metastasis, and dormancy (SAI), as well as in response to therapies (SA2) and 3) characterization and functional relevance of the tumor microenvironment extracellular matrix (ECM) and how tumor cells stroma interactions (i.e. niches) establish metastatic cell fate (SA2). We hypothesize that at least two scenarios influence DTC dormancy. Scenario 1: DTCs from invasive cancers activate stress signals in response to a growth-restrictive target organ microenvironment inducing dormancy. Scenario 2: therapy and/or micro-environmental stress conditions (e.g. hypoxia) acting on primary tumor cells carrying a "dormancy signature" primes newly DTCs to enter dormancy. Based on these two scenarios we propose to 1) isolate DTCs and identify microenvironment-specific gene programs driving DTC dormancy (Scenario 1) and 2) determine whether primary tumor "stress microenvironments" trigger long-term dormancy of DTCs (Scenario 2). Findings in both aims will be validated using archived human primary and metastatic tumors. using human squamous (HEp3) and mouse breast carcinoma models (MMTV-Neu), we found that low ERK1/2 (mitogenic) and high p38a/p (stress) signaling activated dormancy of DTCs. Tumor cells spontaneously disseminated to lungs, lymph nodes (LN) and bone marrow (BM). A short-term dormancy period (2-3 weeks) preceded expansion of lung DTCs. However, BM DTCs persisted in a dormant state (Scenario 1). Systemic inhibition of p38a/p eliminated the short-term dormancy of lungs DTCs and also fueled growth even in sites where it is never observed like spleen, liver and BM. Thus, DTCs might remain occult and dormant in growth restrictive sites (Scenario 1). We also identified a specific gene expression program (signature) in dormant HEp3 cells that is present in cell lines derived from BM DTCs. Importantly, patients whose breast primary tumors carried this dormancy gene signature remained metastasis free for longer periods than those negative for the signature (Scenario 2). We also found that exposure to sub-lethal doses of y-radiation or oxidative stress ignited in surviving cells a dormancy state (Scenario 2). These preliminary data further support the important progress we have made in understanding the scenarios we propose to explore in our specific aims.