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

原发性肝癌成功治疗后存在播散性肿瘤细胞（DTC） 肿瘤是转移的危险因素，而转移是癌症死亡的主要原因。但目前的 关于控制DTC状态的机制（持续休眠对重新激活）的知识是有限的。只 DTC生物学的详细知识将打开延长缓解的治疗选择。 我们证明了转录因子NR 2F 1/COUP-TFI触发了DTC的休眠期， 在头颈部鳞状细胞癌（HNSCC）中，通过调节视黄酸通路并诱导 长期的细胞周期停滞。在这里，我们提出了新的初步数据表明，休眠HNSCC DTC 群体是异质性的，多能性基因SOX 2在DTC亚群中上调 与肺和淋巴结中的NR 2F 1+休眠DTC共存但不同。SOX 2保持 通过上调LIF（白血病抑制因子）和OSM（制瘤素M）信号传导以及通过 抑制视黄酸和MYC相关基因。此外，SOX 2驱动的休眠程序涉及 染色质重塑，似乎决定了更短的休眠期，从而促进更高的转移 启动能力（再激活）。 我们假设SOX 2诱导的休眠是通过增强子调控和LIF/OSM信号传导实现的。 其比不易再活化的细胞促进更大的再活化潜力和转移起始能力 NR 2F 1+故障诊断码。我们还建议，一个持久的休眠状态，具有较低的再激活潜力， 通过诱导NR 2F 1活性在SOX 2 + DTC中诱导。最后，我们建议可以选择性地 由于其较高的再活化率，被化疗靶向。这项研究的具体目标是： SA 1.探讨DTC中SOX 2控制的休眠机制和再激活率。我们 将识别和功能化SOX 2（包括LIF/OSM）的转录靶点，以控制休眠 和使用ChIP-Seq分析的再活化率，功能的获得和丧失，肺外植体器官培养模型， 和人体生物样本的验证。 SA 2.为了确定是否可以针对SOX 2+休眠DTC以抑制其重新激活，或 淘汰我们将确定1-SOX 2驱动的休眠程序是否可以转换为NR 2F 1- 通过使用诱导NR 2F 1活性和2-无论SOX 2+的方案， 与NR 2F 1+相比，DTC的再活化率更高，因此可通过化疗选择性靶向 利用细胞条形码和克隆跟踪技术进行DTC。 我们的长期目标是确定DTC状态的预测性生物标志物（休眠与增殖） 并获得治疗策略所需的洞察力，以将DTC维持在稳定的休眠期， 促使它们被消灭。

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.