Defining epigenetic regulators of tumor heterogeneity and metastasis in melanoma

表观遗传景观限制了分化细胞的发育潜力，但它们的放松管制允许 癌细胞去分化为转录异质细胞状态。这种转录异质性 和表型可塑性定义了许多癌症，包括黑色素瘤，并被认为是癌症的根本原因 转移性扩散。尽管这种可塑性通常与癌症进展和不良预后相关 对于患者来说，目前尚不清楚表观遗传变化如何消除发育限制，从而使细胞获得 生物特征谱在转录上独特的细胞状态之间相互转换。 通过分析人类原发性和转移性皮肤黑色素瘤的 DNA 甲基化谱 我们发现核受体 NR2F2 的替代启动子在患者中去甲基化 转移性黑色素瘤。这种表观遗传变化使得 NR2F2-isoform 2 – 在神经嵴细胞中表达并 当它们分化为黑素细胞时被沉默，从而重新表达。初步功能研究 表明 NR2F2-isoform 2 表达对于转移至关重要，但对原发性黑色素瘤生长并不重要，并且它会影响 神经嵴和上皮间质转化相关基因集。基于这些研究，我们 假设 NR2F2-亚型 2 的去抑制会引发转录变化，从而影响 定义黑色素瘤细胞的表型异质性，允许这些细胞的子集传播 并转移至远处器官。为了检验这个假设，我们建议： • 在小鼠和患者来源的黑色素瘤模型中抑制或促进 NR2F2-isoform 2 启动子甲基化 测量黑色素瘤异质性和转移潜力的变化； • 确定受NR2F2-isoform 2 及其伙伴影响的转录网络；和 • 将原发患者中NR2F2-亚型2、其转录辅助因子和靶标的表达关联起来 原发性黑色素瘤切除后出现转移复发的样本。 该项目的成功完成有望对黑色素瘤和转移领域产生重大影响 因为它会： • 为替代转录因子亚型的表观遗传失调提供概念框架 影响黑色素瘤细胞去分化为表型异质细胞状态； • 确定导致早期肿瘤转移进展的细胞状态；和 • 确定预后标志物和治疗目标。 这些将使我们能够预测、预防或治疗早期黑色素瘤患者的转移进展，从而减少 复发性黑色素瘤患者的发病率和死亡率，同时使无肿瘤患者免受毒副作用的影响 不必要干预的影响和成本。

Epigenetic landscapes restrict the developmental potential of differentiated cells, but their deregulation allows cancer cells to de-differentiate into transcriptionally heterogeneous cell states. This transcriptional heterogeneity and phenotypic plasticity define many cancers, including melanoma, and are thought to be the root cause of metastatic spread. Although this plasticity often correlates with cancer progression and poor prognosis in patients, it is still unclear how epigenetic changes erode developmental constraints to allow cells to acquire a spectrum of biological features as they interconvert between transcriptionally distinctive cell states. By analyzing the DNA methylation profiles of primary and metastatic cutaneous melanomas from human patients we discovered an alternative promoter of the nuclear receptor NR2F2 becomes de-methylated in metastatic melanomas. This epigenetic change allows NR2F2-isoform 2 – expressed in neural crest cells and silenced when they differentiate into melanocytes – to become re-expressed. Preliminary functional studies suggest NR2F2-isoform 2 expression is critical for metastasis but not primary melanoma growth and it affects neural crest and epithelial-to-mesenchymal transition associated gene sets. Based on these studies, we hypothesize that de-repression of NR2F2-isoform 2 elicits transcriptional changes that influence the phenotypic heterogeneity that defines melanoma cells, allowing a subset of these cells to disseminate and metastasize to distant organs. To test this hypothesis, we propose to: • inhibit or promote NR2F2-isoform 2 promoter methylation in mouse and patient-derived melanoma models to measure changes in melanoma heterogeneity and metastatic potential; • identify transcriptional networks that are influenced by NR2F2-isoform 2 and its partners; and • correlate the expression of NR2F2-isoform 2, its transcriptional co-factors and targets in primary patient samples with their metastatic recurrence after primary melanoma resection. Successful completion of this project promises to significantly impact both the melanoma and metastasis fields because it will: • provide a conceptual framework for how epigenetic de-regulation of an alternative transcription factor isoform influences the de-differentiation of melanoma cells into phenotypically heterogeneous cell states; • identify the cell state responsible for metastatic progression in early-stage tumors; and • identify prognostic markers and therapeutic targets. These will allow us to predict, prevent, or treat metastatic progression in early-stage melanoma patients, reducing morbidity and mortality in patients with recurrent melanoma, while sparing tumor-free patients from toxic side effects and cost of unnecessary interventions.