This paper investigates the origin and molecular drivers of Group 4 (G4) medulloblastoma (MB), a common and deadly pediatric brain tumor. Researchers propose that G4 MB arises from failed differentiation of specific progenitor cells located in the human-specific rhombic lip subventricular zone (RLSVZ) of the developing cerebellum. Key findings center on the CBFA complex, showing that mutually exclusive alterations in genes like CBFA2T2, CBFA2T3, and PRDM6 converge to disrupt this complex, thereby stalling the developmental process in RLSVZ progenitor cells. The study also identifies OTX2 overexpression as an alternative mechanism that maintains the progenitor state by inhibiting the CBFA complex, supporting a model where the unique expansion of the human rhombic lip predisposes individuals to these cancers. Furthermore, the location of G3 and G4 MB tumors is explained by the embryological remnant of the internalized rhombic lip, which may persist as a pre-malignant lesion called PeRLs.

References:

• Hendrikse L D, Haldipur P, Saulnier O, et al. Failure of human rhombic lip differentiation underlies medulloblastoma formation[J]. Nature, 2022, 609(7929): 1021-1028.