Modeling medulloblastoma in vivo and with human cerebellar organoids

Abstract

Medulloblastoma (MB) is the most common malignant brain tumor in children and among the subtypes, Group 3 MB has the worst outcome. Here, we perform an in vivo, patientspecific screen leading to the identification of Otx2 and c-MYC as strong Group 3 MB inducers. We validated our findings in human cerebellar organoids where Otx2/c-MYC give rise to MB-like organoids harboring a DNA methylation signature that clusters with human Group 3 tumors. Furthermore, we show that SMARCA4 is able to reduce Otx2/c-MYC tumorigenic activity in vivo and in human cerebellar organoids while SMARCA4 T910M, a mutant form found in human MB patients, inhibits the wild-type protein function. Finally, treatment with Tazemetostat, a EZH2-specific inhibitor, reduces Otx2/c-MYC tumorigenesis in ex vivo culture and human cerebellar organoids. In conclusion, human cerebellar organoids can be efficiently used to understand the role of genes found altered in cancer patients and represent a reliable tool for developing personalized therapies.

Organoid Models of Glioblastoma to Study Brain Tumor Stem Cells

“…Tumors other than GBM did not develop despite the genetic manipulation of genes classically altered in these tumors, such as the deletion of the inhibitory Sonic Hedgehog (SHH) receptor PTCH1 in SHH-group medulloblastoma (Bian et al, 2018). However, the oncogenic effect of PTCH1 deletion is known to be cell-type specific (Schüller et al, 2008) and might therefore necessitate organoid pre-differentiation down the cerebellar route for transformation to occur (Ballabio et al, 2020).…”

“…In the future, it would be interesting to develop a similar approach to model and study prenatal and childhood tumors, such as pediatric gliomas and medulloblastomas, which should maintain a closer link to their developmental origin (Liu and Zong, 2012;Azzarelli et al, 2018;Lu et al, 2019). As medulloblastoma did not develop in organoids, even when genetic alterations typical of this tumors were introduced, it might be necessary to generate regionalized organoids (Muguruma et al, 2015;Dias and Guillemot, 2017;Renner et al, 2017;Ballabio et al, 2020) tailored to the area of origin of that specific tumor, prior to transformation.…”

DNA Methylation Profiling for Diagnosing Undifferentiated Sarcoma with Capicua Transcriptional Receptor (CIC) Alterations

“…Global profiling methylation data were also compared to 32 samples randomly extracted from internal and external datasets [21] among those classifying as central nervous system neuroblastoma FOXR2 (CNS-NB-FOXR2), CIC rearranged sarcoma (EFT-CIC), high-grade neuroepithelial tumor MN1 (HGNET-MN1), and high-grade neuroepithelial tumor BCOR (HGNET-BCOR) using the Heidelberg brain tumor and sarcoma classifier. Bead Chip data were analyzed by means of R (V. 3.4.4) package minfi (V. 1.24.0) to obtain normalized beta values and to perform multidimensional scaling (MDS) analysis, as previously described [18][19][20]. Our patient displayed global methylation levels close to those of Ewing Family Tumor (EFT)-CIC, as evidenced by MDS performed on the 1000 most variable islands in the cohort (Figure 3).…”

“…Tumor areas with the highest tumor cell content (≥70%) were selected for DNA extraction. Samples were analyzed using Illumina Infinium Human Methylation EPIC Bead Chip (EPIC) (Illumina, San Diego, CA, USA) arrays according to the manufacturer's instructions, as previously reported [18][19][20]. In detail, 500 ng DNA were used as input material for fresh frozen tissue.…”

Exposure of Human Skin Organoids to Low Genotoxic Stress Can Promote Epithelial-to-Mesenchymal Transition in Regenerating Keratinocyte Precursor Cells

“…The development of human three-dimensional (3D) organoids by bioengineering now permits these models to make an increasing contribution to deciphering developmental processes, tissue and organ physiology and pathophysiological contexts. Notably, achievements have been reported with heart organoids in the domain of myocardial infarction and drug cardiotoxicity [1], with brain organoids for studies of hypoxic brain injury and prematurity [2] and medulloblastoma modeling [3], with liver organoids for studies of normal [4] and cancer [5] development, and with organoids modeling normal and cancer contexts in the digestive tract [6,7]. In skin, human 3D organoids have demonstrated efficiency in the modeling of pathophysiological contexts, such as defects in the epidermal barrier associated with atopic dermatitis [8], or epidermal cancer proneness in xeroderma pigmentosum [9].…”