Bamezai Shiva, Pulikkottil Alex Jose, Yadav Tribhuwan, Vegi Naidu M, Mueller Julia, Mark Jasmin, Mandal Tamoghna, Feder Kristin, Ihme Susann, Song Chenlin, Rosler Reinhild, Wiese Sebastian, Hoell Jessica I, Kloetgen Andreas, Karsan Aly, Kumari Ankita, Wojenski Luke, Sinha Amit U, Gonzalez-Menendez Irene, Quintanilla-Martinez Leticia, Donato Elisa, Trumpp Andreas, Kruse Elisabeth, Hamperl Stephan, Zou Lee, Rawat Vijay P S, Buske Christian
Institute of Experimental Cancer Research, University Hospital of Ulm, Ulm, Germany.
Department of Pathology, Massachusetts General Hospital Cancer Center, Harvard Medical School, Charlestown, MA.
Blood. 2023 Jul 6;142(1):90-105. doi: 10.1182/blood.2022018651.
RNA-binding proteins (RBPs) form a large and diverse class of factors, many members of which are overexpressed in hematologic malignancies. RBPs participate in various processes of messenger RNA (mRNA) metabolism and prevent harmful DNA:RNA hybrids or R-loops. Here, we report that PIWIL4, a germ stem cell-associated RBP belonging to the RNase H-like superfamily, is overexpressed in patients with acute myeloid leukemia (AML) and is essential for leukemic stem cell function and AML growth, but dispensable for healthy human hematopoietic stem cells. In AML cells, PIWIL4 binds to a small number of known piwi-interacting RNA. Instead, it largely interacts with mRNA annotated to protein-coding genic regions and enhancers that are enriched for genes associated with cancer and human myeloid progenitor gene signatures. PIWIL4 depletion in AML cells downregulates the human myeloid progenitor signature and leukemia stem cell (LSC)-associated genes and upregulates DNA damage signaling. We demonstrate that PIWIL4 is an R-loop resolving enzyme that prevents R-loop accumulation on a subset of AML and LSC-associated genes and maintains their expression. It also prevents DNA damage, replication stress, and activation of the ATR pathway in AML cells. PIWIL4 depletion potentiates sensitivity to pharmacological inhibition of the ATR pathway and creates a pharmacologically actionable dependency in AML cells.
RNA结合蛋白（RBPs）构成了一类庞大且多样的因子，其中许多成员在血液系统恶性肿瘤中过表达。RBPs参与信使核糖核酸（mRNA）代谢的各种过程，并防止有害的DNA:RNA杂交体或R环形成。在此，我们报告，PIWIL4是一种与生殖干细胞相关的RBPs，属于核糖核酸酶H样超家族，在急性髓系白血病（AML）患者中过表达，对白血病干细胞功能和AML生长至关重要，但对健康人类造血干细胞而言并非必需。在AML细胞中，PIWIL4与少数已知的piwi相互作用RNA结合。相反，它主要与注释为蛋白质编码基因区域和增强子的mRNA相互作用，这些区域富含与癌症和人类髓系祖细胞基因特征相关的基因。AML细胞中PIWIL4的缺失下调了人类髓系祖细胞特征和白血病干细胞（LSC）相关基因，并上调了DNA损伤信号。我们证明PIWIL4是一种R环解析酶，可防止R环在一部分AML和LSC相关基因上积累并维持其表达。它还可防止AML细胞中的DNA损伤、复制应激和ATR途径的激活。PIWIL4的缺失增强了对ATR途径药理学抑制的敏感性，并在AML细胞中产生了药理学上可利用的依赖性
