BRAF alteration status and the histone H3F3A gene K27M mutation segregate spinal cord astrocytoma histology.
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ABSTRACT:
SUBMITTER: Shankar GM
PROVIDER: S-EPMC4698284 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:INTRODUCTION: Mutations in H3F3A, which encodes histone H3.3, commonly occur in pediatric glioblastoma. Additionally, H3F3A K27M substitutions occur in gliomas that arise at midline locations (eg, pons, thalamus, spine); moreover, this substitution occurs mainly in tumors in children and adolescents. Here, we sought to determine the association between H3F3A mutations and adult thalamic glioma. METHODS: Genomic H3F3A was sequenced from 20 separate thalamic gliomas. Additionally, for 14 of the 20 gliomas, 639 genes--including cancer-related genes and chromatin-modifier genes--were sequenced, and the Infinium HumanMethylation450K BeadChip was used to examine DNA methylation across the genome. RESULTS: Of the 20 tumors, 18 were high-grade thalamic gliomas, and of these 18, 11 were from patients under 50 years of age (median age, 38 y; range, 17-46), and 7 were from patients over 50 years of age. The H3F3A K27M mutation was present in 10 of the 11 (91%) younger patients and absent from all 7 older patients. Additionally, H3F3A K27M was not detected in the 2 diffuse astrocytomas. Further sequencing revealed recurrent mutations in TP53, ATRX, NF1, and EGFR. Gliomas with H3F3A K27M from pediatric or young adult patients had similar, characteristic DNA methylation profiles. In contrast, thalamic gliomas with wild-type H3F3A had DNA methylation profiles similar to those of hemispheric glioblastomas. CONCLUSION: We found that high-grade thalamic gliomas from young adults, like those from children and adolescents, frequently had H3F3A K27M.
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Project description:Diffuse midline glioma (DMG) is a devastating disease that is defined by its localization, by the diffuse growth of astrocytic tumor cells, and by K27M mutations within Histone H3 proteins. In a large series of such tumor samples (n=83), we show here that 12 % of these cases (n=10) harbor concomitant hotspot mutations within FGFR1 or BRAF. Respective cases were all located in midline structures and matched with reference cases of DMG using global DNA methylation profiling. TP53 mutations were significantly more frequent in BRAF/FGFR1 wild type cases. Presence of hotspot mutations within FGFR1 or BRAF was associated with a significantly better overall survival, which was independent of the patients’ age and tumor localization. Thus, our results establish the relevance of FGFR1 or BRAF mutations in DMG as a prognostic marker and open new targeted therapy options in this subgroup of DMG.
2020-12-08 | GSE161944 | GEO
Project description:Due to the rare incidence of spinal cord astrocytomas, their molecular features remain unclear. Here, we characterized the landscapes of mutations in H3 K27M, isocitrate dehydrogenase 1 (IDH1) R132H, BRAF V600E, and the TERT promoter in 83 diffuse spinal cord astrocytic tumors. Among these samples, thirty-five patients had the H3 K27M mutation; this mutant could be observed in histological grade II (40%), III (40%), and IV (20%) astrocytomas. IDH1 mutations were absent in 58 of 58 cases tested. The BRAF V600E mutation (7/57) was only observed in H3-wildtype astrocytomas, and was associated with a better prognosis in all histological grade II/III astrocytomas. TERT promoter mutations were observed in both H3 K27M-mutant (4/25) and -wildtype (9/33) astrocytomas, and were associated with a poor prognosis in H3-wildtype histological grade II/III astrocytomas. In the 2016 WHO classification of CNS tumors, H3 K27M-mutant diffuse midline gliomas, including spinal cord astrocytomas, are categorized as WHO grade IV. Here, we noticed that the median overall survival of histological grade II/III H3 K27M-mutant cases (n =?28) was significantly longer than that of either the total histological grade IV cases (n =?12) or the H3 K27M-mutant histological grade IV cases (n =?7). We also directly compared H3 K27M-mutant astrocytomas to H3-wildtype astrocytomas of the same histological grade. In histological grade II astrocytomas, compared to H3-wildtype cases (n?=?37), H3 K27M-mutant patients (n?=?14) had showed a significantly higher Ki-67-positive rate and poorer survival rate. However, no significant differences in these parameters were observed in histological grade III and IV astrocytoma patients. In conclusion, these findings indicate that spinal cord astrocytomas are considerably different from hemispheric and brainstem astrocytomas in terms of their molecular profiles, and that the histological grade cannot be ignored when assessing the prognosis of H3 K27M-mutant spinal cord astrocytomas.
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