Donald K. Johnson Eye Institute, Krembil Research Institute, University Health Network, Toronto, ON, M5T 2S8, Canada.
Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON, M5S 1A8, Canada.
Commun Biol. 2022 Jun 9;5(1):569. doi: 10.1038/s42003-022-03507-5.
Spontaneous mouse models of medulloblastoma (MB) offer a tractable system to study malignant progression in the brain. Mouse Sonic Hedgehog (Shh)-MB tumours first appear at postnatal stages as preneoplastic changes on the surface of the cerebellum, the external granule layer (EGL). Here we compared traditional histology and 3DISCO tissue clearing in combination with light sheet fluorescence microscopy (LSFM) to identify and quantify preneoplastic changes induced by disrupting stromal Norrin/Frizzled 4 (Fzd4) signalling, a potent tumour inhibitory signal in two mouse models of spontaneous Shh-MB. We show that 3DISCO-LSFM is as accurate as traditional histology for detecting Norrin/Fzd4-associated changes in PNL formation in Ptch mice and EGL hyperplasia in Neurod2-SmoA1 mice. Moreover, we show that the anti-tumour effect of Norrin/Fzd4 signalling is restricted to the posterior region of the cerebellum and is characterized by defective neural progenitor migration away from the EGL. In conclusion, 3DISCO-LSFM is a valid way to monitor tumour initiation events in mouse MB models and reveals an unanticipated regional restriction of stromal signalling in constraining tumour initiation.
自发的髓母细胞瘤（MB）小鼠模型为研究大脑中的恶性进展提供了一个易于处理的系统。在小脑表面，即外颗粒层（EGL）上，出现了鼠 Sonic Hedgehog（Shh）-MB 肿瘤的新生变化，这些肿瘤是先出现的。在这里，我们比较了传统的组织学和 3DISCO 组织透明化，结合光片荧光显微镜（LSFM），以识别和量化破坏基质 Norrin/Frizzled 4（Fzd4）信号引起的新生变化，这是两种自发 Shh-MB 小鼠模型中的一种有效的肿瘤抑制信号。我们表明，3DISCO-LSFM 与传统组织学一样准确，可用于检测 Ptch 小鼠中 PNL 形成和 Neurod2-SmoA1 小鼠中 EGL 增生相关的 Norrin/Fzd4 变化。此外，我们表明，Norrin/Fzd4 信号的抗肿瘤作用仅限于小脑的后区，其特征是神经前体细胞从 EGL 向外迁移的缺陷。总之，3DISCO-LSFM 是监测小鼠 MB 模型中肿瘤起始事件的有效方法，揭示了基质信号在限制肿瘤起始中的出乎意料的区域限制。
