Functional Analysis of Distinct and Co-existing Transcriptional Programs Regulating Tumor Dormancy

原发肿瘤治疗成功后出现播散性肿瘤细胞(DTC) 肿瘤是肿瘤转移的危险因素，是癌症死亡的主要原因。但是，当前 关于DTC状态的控制机制(持续休眠与重新激活)的知识有限。仅限 对DTC生物学的详细了解将开启延长缓解的治疗方案。 我们证明了转录因子NR2F1/COUP-TFI触发了DTCs的休眠期 在头颈部鳞状细胞癌(HNSCC)中通过调节维甲酸途径和诱导 持久的细胞周期停滞。在这里，我们提供了新的初步数据，表明休眠的HNSCC DTC 群体是异质性的，多能性基因SOX2在DTC的一个亚群中上调 在肺和淋巴结中与NR2F1+休眠的DTCs共存，但不同于NR2F1+。SOX2维护 上调LIF(白血病抑制因子)和OSM(抑癌素M)信号及通过 抑制维甲酸和MYC相关基因。此外，SOX2驱动的休眠计划包括 染色质重塑，似乎决定了一个更短的休眠期，从而促进更高的转移 启动能力(重新激活)。 我们假设SOX2诱导的休眠是通过增强子调节和LIF/OSM信号来实现的 与不易再激活的患者相比，这有助于更大的再激活潜力和转移启动能力 NR2F1+DTC。我们还提出，具有较低重新激活潜力的持续休眠状态可以是 通过诱导NR2F1活性在SOX2+DTCs中诱导。最后，我们提出SOX2+DTC可以选择性地 因其较高的复发率而成为化疗的靶点。这项研究的具体目的是： SA1.探讨SOX2对DTCs休眠机制及复活率的调控作用。我们 将确定SOX2(包括LIF/OSM)的转录靶标并使其在控制休眠中发挥作用 ChIP-Seq分析复活率、功能得失、肺-外植体器官培养模型、 以及在人类生物标本中的验证。 SA2.确定是否可以针对SOX2+休眠的DTC来抑制其重新激活或 被淘汰了。我们将确定1-SOX2驱动的休眠程序是否可以转换为NR2F1- 通过使用协议诱导NR2F1活性和2-是否SOX2+来驱动具有低再激活潜力的程序 与NR2F1+相比，DTCs可以有选择地成为化疗的靶点，因为它们的再激活率更高 使用细胞条形码和克隆跟踪技术。 我们的长期目标是确定DTC状态的预测生物标志物(休眠与增殖) 并获得治疗策略所需的洞察力，以保持DTC处于稳定的休眠阶段或 促使他们被根除。

Presence of disseminated tumor cells (DTCs) following successful treatment of primary tumors poses a risk factor for metastasis which is the leading cause of cancer mortality. However, current knowledge on mechanisms controlling the state of DTCs (persistent dormancy vs. reactivation) is limited. Only detailed knowledge of DTC biology will open therapeutic alternatives which will extend remission. We demonstrated that the transcription factor NR2F1/COUP-TFI triggers the dormancy phase of DTCs in head and neck squamous cell carcinoma (HNSCC) by regulating the retinoic acid pathway and inducing a long-lasting cell cycle arrest. Here we present new preliminary data showing that the dormant HNSCC DTC population is heterogeneous and that the pluripotency gene SOX2 is upregulated in a subpopulation of DTCs that co-exist with, but are distinct from, NR2F1+ dormant DTCs in the lungs and lymph nodes. SOX2 maintains the dormancy of DTCs by upregulating LIF (leukemia inhibitory factor) and OSM (oncostatin M) signaling and by repressing retinoic acid- and MYC-related genes. In addition, the SOX2-driven dormancy program involves chromatin remodeling and appears to dictate a much shorter dormancy phase that facilitates higher metastasis initiating capacity (reactivation). We hypothesize that SOX2-induced dormancy is enabled via enhancer regulation and LIF/OSM signaling which facilitates greater reactivation potential and metastasis-initiating capacity than the less reactivation prone NR2F1+ DTCs. We also propose that a persistent state of dormancy with lower reactivation potential can be induced in SOX2+ DTCs by inducing NR2F1 activity. Lastly, we propose that SOX2+ DTCs can be selectively targeted by chemotherapy due to their higher reactivation rate. The specific aims of this study are: SA1. To identify the mechanism of dormancy and the reactivation rate controlled by SOX2 in DTCs. We will identify and functionalize the transcriptional targets of SOX2 (including LIF/OSM) in controlling the dormancy and rate of reactivation by using ChIP-Seq analysis, gain and loss of function, lung-explant organ culture model, and validation in human biospecimens. SA2. To determine whether SOX2+ dormant DTCs can be targeted to inhibit their reactivation or eliminated. We will determine 1- whether SOX2-driven dormancy program can be converted into an NR2F1- driven program with low reactivation potential by using protocols to induce NR2F1 activity and 2- whether SOX2+ DTCs can be selectively targeted by chemotherapy due to their higher reactivation rate, compared to NR2F1+ DTCs by using cellular barcoding and clonal tracking technology. Our long-term objective is to identify predictive biomarkers of the DTC status (dormant vs proliferating) and to gain insight necessary for therapeutic strategies to either maintain DTCs in a stable dormancy phase or induce their eradication.