Tumor organoids recapitulate pathological properties and would serve as an excellent ex vivo model for drug discovery. Here, we performed an unbiased drug screening on drivers-defined tumor organoids from mouse endometrial cancer, the most prevalent gynecological malignancy in human, with a small molecule library targeting epigenetic factors. Among them, menin-MLL inhibitors MI-136 and MI-463 scored. The therapeutic capacity of MI-136 was further validated in tumor organoids in vitro and an orthotopic model in vivo. CRISPR/cas9-mediated mutations of major components of the menin-MLL complex, Men1, Kmt2a and Ash2l, inhibited the growth of tumor organoids, suggesting that the complex was the target of MI-136. Transcriptome analysis showed that the hypoxia-inducible factor (HIF) pathway was the most significantly downregulated pathway by MI-136 treatment. Consistently, Men1, Kmt2a, and Ash2l knockout also repressed the expressions of the HIF target genes. Loss of Hif1a or Hif1b partially phenocopied the inhibition of the menin-MLL complex by MI-136 or mutations in term of tumor organoid growth. Further, we found that MEN1 was upregulated in human endometrial cancers, which were tightly correlated with the expression levels of HIF1A, and associated with poor prognosis. Importantly, MI-136 also significantly inhibited the growth of endometrial cancer organoids derived from patients. Thus, our study identified MI-136 as a potential inhibitor for endometrial cancer through regulating the HIF pathway, a novel molecular mechanism distinguished from those in AML and prostate cancer.

肿瘤类器官概括了病理特性，并将作为药物发现的极好离体模型。在这里，我们对来自小鼠子宫内膜癌（人类最普遍的妇科恶性肿瘤）驱动定义的肿瘤类器官进行了无偏见的药物筛选，并使用了一个针对表观遗传因子的小分子库。其中，menin-MLL 抑制剂 MI-136 和 MI-463 得分。MI-136的治疗能力在体外肿瘤类器官和体内原位模型中得到进一步验证。CRISPR/cas9 介导的 menin-MLL 复合物主要成分 Men1、Kmt2a 和 Ash2l 的突变抑制了肿瘤类器官的生长，表明该复合物是 MI-136 的靶标。转录组分析表明，缺氧诱导因子（HIF）通路是 MI-136 处理最显着下调的通路。始终如一，Men1、Kmt2a和Ash2l敲除也抑制了 HIF 靶基因的表达。Hif1a或Hif1b的缺失部分地表型复制了 MI-136 对menin -MLL 复合物的抑制或肿瘤类器官生长方面的突变。此外，我们发现MEN1在人类子宫内膜癌中上调，这与HIF1A的表达水平密切相关，并且与预后不良有关。重要的是，MI-136 还显着抑制了源自患者的子宫内膜癌类器官的生长。因此，我们的研究通过调节 HIF 途径确定 MI-136 是子宫内膜癌的潜在抑制剂，这是一种不同于 AML 和前列腺癌的新分子机制。