Project 3: Targeting PRMT5 in Mantle Cell Lymphoma

项目3摘要 套细胞淋巴瘤（MCL）是一种以异常遗传和表观遗传为特征的不可治愈的B细胞淋巴瘤 事件各种治疗策略已被用于改善MCL患者的结局，包括 免疫化疗和干细胞移植。靶向B细胞受体（BCR）信号传导的方法 伊曲替尼途径显示出前景，然而，结果数据尚不成熟， 很明显因此，对于用于治疗MCL的新型治疗方法仍然存在明确的未满足的需求。我们 已经表明PRMT 5在MCL中选择性过表达，并驱动全局抑制性表观遗传标记 抑制调节基因和肿瘤抑制基因。用shRNA启动子敲低PRMT 5 选择性MCL毒性，这使我们假设PRMT 5是这种疾病的有吸引力的靶标。我们有 开发了一种“一流”的药物，选择性地抑制PRMT 5活性，IC 50在低nM范围内。我们的首席 药物对淋巴瘤而不是正常B细胞有毒，在体内耐受性良好，在体内具有令人印象深刻的抗肿瘤活性。 MCL的临床前动物模型。PRMT 5抑制剂已被用作化学探针，以剖析关键的 MCL肿瘤细胞利用的途径。用PRMT 5特异性抗体进行初步全基因组作图 表观遗传标记和全转录组测序（RNA-Seq，与WCM合作）， PRMT 5抑制剂的缺乏揭示了广泛的信号传导、存活和生长途径， 由这种酶控制。我们的初步工作发现PRMT 5直接靶向调控基因， 如PTPROt、TRIB 3和PIK 3 IP 1，其负调节BCR和PI 3 K/AKT通路。失活 组成型AKT活性导致FOXO 1的去磷酸化，促进其抗-HLA-D1的表观遗传调节。 癌基因表达我们发现，PRMT 5抑制导致多个微- 可能消耗细胞周期蛋白D1导致RB激活和RB/E2 F调节恢复的RNA 网络因此，PRMT 5抑制导致RB/E2 F介导的EZH 2、SUZ 12和EED沉默， 表观遗传阻遏物PRC 2复合物的组成部分，一个赖氨酸甲基转移酶家族， 在MCL中频繁突变和激活。因此，通过抑制PRMT 5，我们可以实现直接抑制 抑制性精氨酸表观遗传标记，同时间接消耗赖氨酸抑制性标记，如H3 K27（Me 3）， 可能是FOXO 1的靶点我们抑制像PRMT 5这样的核心参与者的策略导致了一种新的方法， 在多个水平恢复MCL细胞的调节，包括表观基因组、BCR、PI 3 K/AKT和细胞周期蛋白 D/RB-E2 F途径。我们提出了整合全基因组的方法和策略， 创新的临床前MCL模型，以研究PRMT 5抑制如何规避耐药性 在临床试验和临床前工作中提出的新型分子靶向药物中遇到的问题 项目1和2。我们提出了一种创新的，直接的和强大的方法来发现遗传 他们将利用这些信息来开发治疗这种不治之症的新策略。

Project 3 Summary Mantle cell lymphoma (MCL) is an incurable B-cell lymphoma characterized by aberrant genetic and epigenetic events. A variety of therapeutic strategies have been used to improve the outcome of MCL patients including immune-chemotherapy and stem cell transplantation. Approaches targeting the B cell receptor (BCR) signaling pathway with ibrutinib have shown promise, however, outcome data is immature and emerging resistance is clearly evident. Thus there remains a clear, unmet need for novel therapeutic approaches for treating MCL. We have shown that PRMT5 is selectively over expressed in MCL and drives global repressive epigenetic marks on chromatin to silence regulatory and tumor suppressor genes. PRMT5 knock down with shRNA promotes selective MCL toxicity which led us to hypothesize that PRMT5 is an attractive target for this disease. We have developed a “first-in-class” drug that selectively inhibits PRMT5 activity with IC50 in low nM range. Our lead drug is toxic to lymphoma, not normal B cells, is well tolerated in vivo with impressive anti-tumor activity in preclinical animal models of MCL. PRMT5 inhibitors have been used as chemical probes to dissect out critical pathways utilized by MCL tumor cells. Preliminary whole genome mapping with antibodies specific for PRMT5 epigenetic marks and whole transcriptome sequencing (RNA-Seq, in collaboration with WCM) in presence and absence of PRMT5 inhibitors has revealed a broad range of signaling, survival and growth pathways to be governed by this enzyme. Our preliminary work has found that PRMT5 directly targets regulatory genes such as PTPROt, TRIB3, and PIK3IP1 which negatively regulate BCR and PI3K/AKT pathways. Inactivation of constitutive AKT activity leads to dephosphorylation of FOXO1, promoting its epigenetic regulation of anti- cancer gene expression. We discovered that PRMT5 inhibition leads to direct de-repression of multiple micro- RNAs that may deplete CYCLIN D1 leading to activation of RB and restoration of the RB/E2F regulatory network. Consequently, PRMT5 inhibition leads to RB/E2F-mediated silencing of EZH2, SUZ12 and EED, components of the epigenetic repressor PRC2 complex, a family of lysine methyltransferase enzymes that are frequently mutated and activated in MCL. Thus, by inhibiting PRMT5, we can achieve direct inhibition of repressive arginine epigenetic marks while indirectly depleting lysine repressive marks like H3K27(Me3) and possibly, targets of FOXO1. Our strategy to inhibit a central player like PRMT5 has led to a novel approach to restore regulation to the MCL cell at multiple levels including the epigenome, BCR, PI3K/AKT, and CYCLIN D/RB-E2F pathways. We have proposed integrative whole genome approaches and strategies utilizing innovative preclinical MCL models to examine how PRMT5 inhibition can circumvent drug resistance encountered with novel molecularly targeted agents examined in clinical trials and preclinical work proposed in Projects 1 and 2. We present an innovative, straight-forward and robust approach to discover the genetic programs altered in MCL and will use this information to develop new strategies to treat this incurable disease.