Understanding resistance mechanisms to protein arginine methyltransransferase Inhibitors in Lymphoma

项目总结/摘要 非霍奇金淋巴瘤（NHL）是最常见的癌症之一，尽管目前的治疗，许多 病人病情复发。最近的发现涉及表观遗传机制和非- B细胞淋巴瘤患者中典型的致癌程序失调。蛋白质精氨酸 甲基转移酶-5（PRMT 5），负责精氨酸对称二甲基化的主要酶， 组蛋白和非组蛋白在淋巴瘤发生中起着重要作用，控制着 转化的B细胞。PRMT 5在淋巴瘤中过表达，可能代表了一种新的治疗靶点， 这种疾病。为了评估是什么调控因子驱动抗性，我们进行了全基因组CRISPR筛选。 令人惊讶的是，我们发现RNA结合蛋白MUSASHI 2（MSI 2）是最受欢迎的。MSI 2是一种RNA结合蛋白 在大多数植物中表达最高的茎相关蛋白质 侵袭性癌症，但其在B细胞淋巴瘤中的作用尚不清楚。我们的初步数据表明，MSI 2是 PRMT 5在淋巴瘤中高度表达，并且减少减少增殖，其通过PRMT 5抑制进一步减少。 我们还在B细胞淋巴瘤中发现了由PRMT 1和PRMT 5介导的新的翻译后修饰 并证明了这些新发现的修改的功能要求。我们建议研究这个问题 使用遗传小鼠模型、人淋巴瘤细胞系驱动淋巴瘤发生的新PRMT-MSI 2轴 和患者样本。此外，我们利用技术创新来研究直接MSI 2目标， MSI 2如何介导对淋巴瘤中PRMT 5抑制的抗性的机制。这些研究具有广泛的 RBP在B细胞淋巴瘤中如何失调及其功能受PRMT控制的意义。

PROJECT SUMMARY/ABSTRACT Non-Hodgkin’s lymphoma (NHL) is among the most common cancers and despite current therapies many patients relapse from their disease. Recent discoveries have implicated epigenetic mechanisms and non- classical oncogenic programs as dysregulated in patients with B-cell lymphoma. Protein arginine methyltransferase-5 (PRMT5), the major enzyme responsible for the arginine symmetric dimethylation of histones and non-histone proteins, plays an important role in lymphomagenesis, controlling the growth of transformed B cells. PRMT5 is overexpressed in lymphoma and may represent a novel therapeutic target for this disease. In order to assess what regulators drive resistance, we performed a genome wide CRISPR screen. Surprisingly, we uncovered the RNA binding protein MUSASHI2 (MSI2) as the top hit. MSI2 is an RNA binding protein that has been implicated as a stem related protein that is the most highly expressed in the most aggressive cancers but its role in B-cell lymphoma is not known. Our preliminary data suggests that MSI2 is highly expressed in lymphomas and reduction reduces proliferation which is further reduced by PRMT5 inhibition. We also discovered new post-translational modifications mediated by PRMT1 and PRMT5 in B-cell lymphoma and demonstrated a functional requirement for these newly discovered modifications. We propose to study this new PRMT-MSI2 axis in driving lymphomagenesis using genetic mouse models, human lymphoma cell lines and patient samples. Furthermore, we utilize technological innovations to study direct MSI2 targets and the mechanism for how MSI2 mediates resistance to PRMT5 inhibition in lymphoma. These studies have broad implication to how RBPs can become dysregulated and their function controlled by PRMTs in B-cell lymphoma.