髓母细胞瘤的音刺猬亚群 (SHH-MB) 的特点是 SHH 信号通路的异常激活。抑制正 SHH 调节因子 Smoothened (SMO) 已显示出有希望的临床疗效。然而，对 SMO 抑制剂的原发性和获得性耐药性限制了它们的功效。有必要了解治疗耐药的潜在分子机制，以弥补这一未满足的需求。在这里，我们利用小鼠 SMB21 和人类 DAOY 细胞中的全基因组 CRISPR-Cas9 敲除筛选，以阐明遗传依赖性和药物相关的遗传相互作用因子，这些相互作用可以作为 SHH-MB 的替代治疗靶点。我们的筛选强化了 SMB21 细胞作为 SHH-MB 的忠实模型系统（而不是 DAOY 细胞），并确定了表观遗传机制的成员，包括 DNA 甲基转移酶 1 (DNMT1)，作为 SHH 依赖性肿瘤的可药物靶标。我们发现 Dnmt1 在正常小鼠小脑发育中起着至关重要的作用，并且是 SHH-MB 体内生长所必需的。此外，单独使用DNMT1药理抑制以及与SMO抑制相结合，可有效抑制小鼠和人类SHH-MB细胞模型中的肿瘤生长，并通过抑制SMO下游的SHH信号输出来延长SHH-MB小鼠模型的存活时间。总之，我们的数据强调了抑制表观遗传调节因子作为 SMO 抑制剂敏感和耐药 SHH-MB 的一种新型治疗途径的潜力。© 2024。作者。

Sonic hedgehog subgroup of medulloblastoma (SHH-MB) is characterized by aberrant activation of the SHH signaling pathway. An inhibition of the positive SHH regulator Smoothened (SMO) has demonstrated promising clinical efficacy. Yet, primary and acquired resistance to SMO inhibitors limit their efficacy. An understanding of underlying molecular mechanisms of resistance to therapy is warranted to bridge this unmet need. Here, we make use of genome-wide CRISPR-Cas9 knockout screens in murine SMB21 and human DAOY cells, in order to unravel genetic dependencies and drug-related genetic interactors that could serve as alternative therapeutic targets for SHH-MB. Our screens reinforce SMB21 cells as a faithful model system for SHH-MB, as opposed to DAOY cells, and identify members of the epigenetic machinery including DNA methyltransferase 1 (DNMT1) as druggable targets in SHH-dependent tumors. We show that Dnmt1 plays a crucial role in normal murine cerebellar development and is required for SHH-MB growth in vivo. Additionally, DNMT1 pharmacological inhibition alone and in combination with SMO inhibition effectively inhibits tumor growth in murine and human SHH-MB cell models and prolongs survival of SHH-MB mouse models by inhibiting SHH signaling output downstream of SMO. In conclusion, our data highlight the potential of inhibiting epigenetic regulators as a novel therapeutic avenue in SMO-inhibitor sensitive as well as resistant SHH-MBs.© 2024. The Author(s).