美国西雅图福瑞德·哈金森癌症中心Robert K. Bradley小组和纽约纪念斯隆-凯特琳癌症中心Omar Abdel-Wahab小组合作，发现了癌症中剪接体内非典型BAF复合物的破坏，并基于这一机制提出了对待一类肿瘤恶化的治疗方法。 这一研究成果在线发表在2019年10月9日的《自然》上。

研究人员结合泛癌剪接分析与阳性富集CRISPR筛选来优化促进肿瘤发生的拼接改变。研究团队报告说，多样的SF3B1突变集中在对BRD9的抑制上，BRD9是最近描述的非典型BAF染色质重塑复合体的核心组成部分，该复合体也包含GLTSCR1和GLTSCR1L57。突变体SF3B1识别BRD9内的异常的、深内含子分支点，从而诱导内源性逆转录病毒元件衍生的毒性外显子的包被和随后BRD9 mRNA的降解。BRD9的清除引起了CTCF相关基因座上非经典BAF的减少，并促进了黑色素瘤的发生。BRD9是葡萄膜黑色素瘤中一种强有力的抑制剂，利用反义寡核苷酸或CRISPR介导诱变在SF3B1变异细胞中纠正BRD9 的错剪接可以抑制肿瘤增长。

据悉，SF3B1是癌症中最常见的突变RNA剪接因子，但对SF3B1突变促进恶性肿瘤的机制了解甚少。

附：英文原文

Title: Spliceosomal disruption of the non-canonical BAF complex in cancer

Author: Daichi Inoue, Guo-Liang Chew, Bo Liu, Brittany C. Michel, Joseph Pangallo, Andrew R. DAvino, Tyler Hitchman, Khrystyna North, Stanley Chun-Wei Lee, Lillian Bitner, Ariele Block, Amanda R. Moore, Akihide Yoshimi, Luisa Escobar-Hoyos, Hana Cho, Alex Penson, Sydney X. Lu, Justin Taylor, Yu Chen, Cigall Kadoch, Omar Abdel-Wahab, Robert K. Bradley

Issue&Volume: 2019-10-09

Abstract: 

SF3B1 is the most commonly mutated RNA splicing factor in cancer1,2,3,4, but the mechanisms by which SF3B1 mutations promote malignancy are poorly understood. Here we integrated pan-cancer splicing analyses with a positive-enrichment CRISPR screen to prioritize splicing alterations that promote tumorigenesis. We report that diverse SF3B1 mutations converge on repression of BRD9, which is a core component of the recently described non-canonical BAF chromatin-remodelling complex that also contains GLTSCR1 and GLTSCR1L5,6,7. Mutant SF3B1 recognizes an aberrant, deep intronic branchpoint within BRD9 and thereby induces the inclusion of a poison exon that is derived from an endogenous retroviral element and subsequent degradation of BRD9 mRNA. Depletion of BRD9 causes the loss of non-canonical BAF at CTCF-associated loci and promotes melanomagenesis. BRD9 is a potent tumour suppressor in uveal melanoma, such that correcting mis-splicing of BRD9 in SF3B1-mutant cells using antisense oligonucleotides or CRISPR-directed mutagenesis suppresses tumour growth. Our results implicate the disruption of non-canonical BAF in the diverse cancer types that carry SF3B1 mutations and suggest a mechanism-based therapeutic approach for treating these malignancies.

DOI: 10.1038/s41586-019-1646-9

Source: https://www.nature.com/articles/s41586-019-1646-9