Epigenetic Regulation of Head and Neck Cancer Immune Evasion

项目摘要 头颈部鳞状细胞癌（HNSCC）每年影响美国约60，000人。尽管 积极的治疗，HNSCC的5年生存率保持在50%左右，患者经常复发 和转移性病变的发展。我们以前的工作表明，NSD 1，一个组蛋白甲基转移酶， 特异性催化组蛋白H3 Lys 36（H3 K36 me 2）的二甲基化，在HNSCC中经常失活。 在15%的人中发现了NSD 1的缺失、突变和由癌组蛋白H3 K36 M突变引起的生化抑制。 的HNSCC和定义一个新的疾病亚组具有不同的分子和临床特征。但 NSD 1失活促进HNSCC发展的机制尚不清楚。我们最近报道 HNSCC细胞系和患者样本中的NSD 1失活导致了深刻的DNA低甲基化。我们 初步研究进一步证明，HNSCC中的NSD 1突变与基因组DNA水平增加有关。 不稳定性和反转录转座子去阻遏。有趣的是，已知这些分子事件会促进肿瘤 NSD 1突变体肿瘤被宿主免疫系统识别，但NSD 1突变体肿瘤出乎意料地免疫“冷”， 肿瘤浸润性白细胞的存在和干扰素应答降低。因此，我们建议测试 HNSCC中NSD 1失活降低肿瘤免疫原性并促进免疫逃避假说 通过干扰素信号通路的表观遗传沉默。在目标1中，我们将定义NSD 1的作用， HNSCC体内免疫逃避。我们计划采用同基因和基因工程小鼠模型， HNSCC由NSD 1损失驱动，已经在我们的实验室开发。再加上最先进的单细胞 RNA-seq和多重成像技术，我们将研究肿瘤微环境的变化， NSD 1丢失。在目标2中，我们将研究NSD 1调节干扰素应答的表观遗传机制。我们 我建议测试NSD 1拮抗H3 K27三甲基化（H3 K27 me 3）的模型，H3 K27 me 3是一种抑制性组蛋白标记 由EZH 2催化，以维持STAT 1表达。在目标3中，使用同基因和人源化小鼠模型， 我们将测试EZH 2的药理学抑制是否可以恢复免疫浸润并延迟NSD 1的生长。 单独或与免疫检查点抑制剂组合的缺陷型肿瘤。因为只有少数HNSCC 患者对免疫检查点抑制剂有反应，我们的预期结果将立即转化为 通过提名（1）NSD 1/H3 K36 me 2作为用于预测对以下的治疗反应的生物标志物， 免疫疗法和（2）FDA批准的EZH 2抑制剂，其可以与检查点抑制剂组合， 靶向浸润不良的免疫“冷”肿瘤。更广泛地说，这个项目也将有助于我们了解 基于染色质的机制被癌细胞利用来促进免疫逃避。

PROJECT SUMMARY Head and Neck Squamous Cell Carcinomas (HNSCC) affect ~60,000 individuals in the US every year. Despite aggressive treatment, the 5-year survival rate for HNSCC remains ~50% and frequently patients suffer relapse and the development of metastatic lesions. Our previous work showed that NSD1, a histone methyltransferase that specifically catalyzes di-methylation of histone H3 Lys36 (H3K36me2), is frequently inactivated in HNSCC. Deletions, mutations and biochemical inhibition of NSD1 by the oncohistone H3K36M mutation are found in 15% of HNSCC and define a novel disease subgroup with distinct molecular and clinical features. However, the mechanism by which NSD1 inactivation promotes HNSCC development remains unclear. We recently reported that NSD1 inactivation in HNSCC cell lines and patient samples resulted in profound DNA hypomethylation. Our preliminary studies further demonstrated that NSD1 mutations in HNSCC are associated with increased genomic instability and retrotransposon de-repression. Intriguingly, these molecular events are known to promote tumor recognition by host immune system, yet NSD1 mutant tumors are unexpectedly immune “cold” with minimal presence of tumor-infiltrating leukocytes and a reduced interferon response. Therefore, we propose to test the hypothesis that NSD1 inactivation in HNSCC reduces tumor immunogenicity and facilitates immune evasion through epigenetic silencing of the interferon signaling pathway. In Aim 1, we will define the role of NSD1 in HNSCC immune evasion in vivo. We plan to employ syngeneic and genetically engineered mouse models of HNSCC driven by NSD1 loss that have been developed in our lab. Together with the state-of-the-art single-cell RNA-seq and multiplex imaging technologies, we will examine the changes in tumor microenvironment following NSD1 loss. In Aim 2, we will study epigenetic mechanisms by which NSD1 regulates interferon response. We propose to test the model that NSD1 antagonizes H3K27 tri-methylation (H3K27me3), a repressive histone mark catalyzed by EZH2, to maintain STAT1 expression. In Aim 3, using syngeneic and humanized mouse models, we will test if pharmacological inhibition of EZH2 can restore immune infiltration and delay the growth of NSD1- deficient tumors alone or in combination with immune checkpoint inhibitor. Since only a minority of HNSCC patients respond to immune checkpoint inhibitors, our expected results will have immediate translational implication by nominating (1) NSD1/H3K36me2 as biomarkers for predicting therapeutic response to immunotherapy and (2) an FDA-approved EZH2 inhibitor which can be combined with checkpoint inhibitors to target poorly infiltrated, immune “cold” tumors. More broadly, this project will also contribute to our understanding of chromatin-based mechanisms exploited by cancer cells to facilitate immune evasion.