PRMT5 Promotes Progression of Chronic Lymphocytic Leukemia [bulk low-input RNA-Seq]. PRMT5 Promotes Progression of Chronic Lymphocytic Leukemia [bulk low-input RNA-Seq]

Purpose: Richter’s Transformation (RT) is a poorly understood and often fatal progression of chronic lymphocytic leukemia (CLL) manifesting histologically as diffuse large B-cell lymphoma. PRMT5 is implicated in lymphomagenesis, but its role in CLL or RT progression is unknown. We demonstrate herein that tumors uniformly overexpress PRMT5 in patients with progression to RT. Furthermore, mice with B-specific overexpression of hPRMT5 developed a B-lymphoid expansion with increased risk of death, and Eµ-PRMT5/TCL1 double transgenic mice uniformly developed a highly aggressive disease that histologically resembles RT; where large-scale transcriptional profiling identified unique oncogenic pathways that mediate PRMT5-driven disease progression. Taken together, the discovery that PRMT5 drives oncogenic pathways promoting RT provides a compelling rationale for clinical investigation of PRMT5 inhibitors such as PRT382 in aggressive CLL/RT cases Overall design: - RNA-sequencing from B cells isolated from the spleen of Eµ-PRMT5, Eµ-PRMT5/TCL1, and Eµ-TCL1 mice at ERC. - RNA-sequencing and ATAC-sequencing from B cells isolated from the spleen of Eµ-PRMT5/TCL1 and Eµ-TCL1 mice at 3 and 6 months of age. - Single cell RNA-sequencing in Eµ-PRMT5, Eµ-PRMT5/TCL1, and Eµ-TCL1 mice at ERC.

研究目的：里氏转化（Richter’s Transformation, RT）是一种机制尚未阐明且常为致死性的慢性淋巴细胞白血病（chronic lymphocytic leukemia, CLL）进展亚型，其组织学特征表现为弥漫性大B细胞淋巴瘤（diffuse large B-cell lymphoma）。蛋白精氨酸甲基转移酶5（PRMT5）已被证实参与淋巴瘤发生过程，但其在CLL或RT进展中的作用仍不明确。本研究证实，进展为RT的患者其肿瘤组织均存在PRMT5的过表达。此外，B细胞特异性过表达人类PRMT5（hPRMT5）的小鼠出现了B淋巴系扩增，且死亡风险显著升高；而Eµ-PRMT5/TCL1双转基因小鼠（double transgenic mice）均发生了组织学特征与RT高度相似的高侵袭性疾病，通过大规模转录谱分析（transcriptional profiling）鉴定出了介导PRMT5驱动疾病进展的独特致癌通路。综上，PRMT5可驱动促进RT发生的致癌通路这一发现，为针对侵袭性CLL/RT病例开展PRMT5抑制剂（如PRT382）的临床研究提供了强有力的理论依据。

实验设计：
- 对ERC阶段的Eµ-PRMT5、Eµ-PRMT5/TCL1及Eµ-TCL1小鼠脾脏分离的B细胞进行RNA测序（RNA-sequencing）。
- 对3月龄及6月龄的Eµ-PRMT5/TCL1与Eµ-TCL1小鼠脾脏分离的B细胞分别进行RNA测序与ATAC测序（ATAC-sequencing）。
- 对ERC阶段的Eµ-PRMT5、Eµ-PRMT5/TCL1及Eµ-TCL1小鼠进行单细胞RNA测序（single cell RNA-sequencing）。