Elevated TERT Expression in TERT-Wildtype Adult Diffuse Gliomas: Histological Evaluation with a Novel TERT-Specific Antibody

Figure 1

Molecular profile of the glioma cases. (a) Diffuse astrocytic (DA/AA) tumors were characterized by immunopositivity for IDH1 (R132H) and p53, and the loss of immunoreactivity for ATRX. Oligodendroglial tumors demonstrated IDH1 (R132H) immunoreactivity and 1p/19q-codeletion on FISH (red: probes for 1p36 or 19q13, green: probes for the centromere of chromosome 1 or 19). Note that these genotypes of astrocytomas and oligodendrogliomas are mutually exclusive except for IDH genes. IDH-wildtype GBM tumors did not possess mutations in IDH genes. The IDH-wildtype diffuse astrocytoma group did not show any molecular genetic aberrations shown above. (b) Mutations at C228 and C250 of the TERT promoter region were examined for every case by Sanger sequencing. Representative cases were shown for TERT promoter mutations and wildtype TERT. (c) Examination of the frequency of TERT promoter mutations in each group of gliomas. Oligodendroglial tumors and IDH-wildtype GBM possessed high incidence of TERT mutations, followed by the IDH-wildtype diffuse astrocytoma. No grade II and III astrocytic tumors with IDH-mutant showed TERT promoter hotspot mutations. (d) Sanger sequencing results displayed representative cases for TERT promoter common SNPs (T349C). The molecular profile of the cases was summarized in Table 1 and Supplementary Table  . AA, anaplastic astrocytoma; AO, anaplastic oligodendroglioma; AOA, anaplastic oligoastrocytoma; DA, diffuse astrocytoma; GBM, IDH-wildtype glioblastoma; OL, oligodendroglioma; wt, wildtype. Scale bar = 40 μm.

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