PDF(Pubmed)
Abstract：
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.
摘要：
髓母细胞瘤（SHH-MB）的Sonichedgehog亚群的特征在于SHH信号通路的异常激活。阳性SHH调节剂Smoothened（SMO）的抑制已证明有希望的临床疗效。然而，对SMO抑制剂的原发性和获得性耐药性限制了其疗效。有必要了解对治疗耐药的潜在分子机制，以弥合这种未满足的需求。这里,我们在鼠SMB21和人类DAOY细胞中利用全基因组CRISPR-Cas9敲除筛选，为了解开遗传依赖性和药物相关的遗传相互作用物，它们可以作为SHH-MB的替代治疗靶标。我们的屏幕加强SMB21细胞作为SHH-MB的忠实模型系统，与DAOY细胞相反，并确定表观遗传机制的成员，包括DNA甲基转移酶1（DNMT1）作为SHH依赖性肿瘤的药物靶标。我们表明，Dnmt1在正常小鼠小脑发育中起着至关重要的作用，并且是体内SHH-MB生长所必需的。此外,单独的DNMT1药理学抑制以及与SMO抑制组合有效地抑制鼠和人SHH-MB细胞模型中的肿瘤生长,并通过抑制SMO下游的SHH信号传导输出来延长SHH-MB小鼠模型的存活。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的新治疗途径的潜力.
