Here we show that acute myeloid leukemia (AML) cells require the BRD9 subunit of the SWI−SNF chromatin-remodeling complex to sustain MYC transcription, rapid cell proliferation and a block in differentiation. Based on these observations, we derived small-molecule inhibitors of the BRD9 bromodomain that selectively suppress the proliferation of mouse and human AML cell lines. To establish these effects as on-target, we engineered a bromodomain-swap allele of BRD9 that retains functionality despite a radically altered bromodomain pocket. Expression of this allele in AML cells confers resistance to the antiproliferative effects of our compound series, thus establishing BRD9 as the relevant cellular target. Furthermore, we used an analogous domain-swap strategy to generate an inhibitor-resistant allele of EZH2. To our knowledge, our study provides the first evidence for a role of BRD9 in cancer and reveals a simple genetic strategy for constructing resistance alleles to demonstrate on-target activity of chemical probes in cells.

在这里，我们表明，急性髓系白血病 (AML) 细胞需要 SWI−SNF 染色质重塑复合物的 BRD9 亚基来维持MYC转录、快速细胞增殖和分化阻断。基于这些观察，我们衍生出了 BRD9 溴结构域的小分子抑制剂，可选择性抑制小鼠和人类 AML 细胞系的增殖。为了确定这些作用是否达到目标，我们设计了BRD9的布罗莫结构域交换等位基因，尽管布罗莫结构域口袋发生了根本改变，但该等位基因仍保留了功能。该等位基因在 AML 细胞中的表达赋予我们化合物系列的抗增殖作用的抗性，从而将 BRD9 确立为相关的细胞靶标。此外，我们使用类似的结构域交换策略来生成EZH2的抑制剂抗性等位基因。据我们所知，我们的研究为 BRD9 在癌症中的作用提供了第一个证据，并揭示了构建抗性等位基因的简单遗传策略，以证明细胞中化学探针的靶向活性。