The impact of TP53 and RAS mutations on cerebellar glioblastomas

• This is the first report analyzing both TP53 and RAS alterations in cerebellar GBM.
• TP53 mutations were detected in 3 out of 5 patients, mainly in hotspot codons.
• RAS signaling is impaired in cerebellar GBM.
• Premature STOP codon induction in RAS genes might be specific for cerebellar GBM.

Cerebellar glioblastoma (cGBM) is a rare, inadequately characterized disease, without detailed information on its molecular basis. This is the first report analyzing both TP53 and RAS alterations in cGBM. TP53 mutations were detected in more than half of the samples from our cohort, mainly in hotspot codons. There were no activating mutations in hotspot codons 12/13 and 61 of KRAS and HRAS genes in cGBM samples but we detected alterations in other parts of exons 2 and 3 of these genes, including premature induction of STOP codon. This mutation was present in 3 out of 5 patients. High incidence of RAS mutations, as well as significantly longer survival of cGBM patients compared to those with supratentorial GBM suggest that cGBM may have different mechanisms of occurrence. Our results suggest that inactivation of TP53 and RAS may play an important role in the progression of cerebellar GBM.