Page 163 - Molecular features of low-grade developmental brain tumours

MIR-519D & MIR-4758 CAN IDENTIFY GG FROM DNT AND ASTROCYTOMAS
Figure 2. In situ hybridization of miR-519d and miR-4758 expression in peritumoural cortex and ganglioglioma. Panels A and F: Normal appearing peritumoural cortex (ctx); miR-519d (A) and miR-4758 (F) were weakly expressed in neurons (arrows) and could not be detected in glial cells. Panels B-C and G-H: GG; miR-519d (B-C) and miR-4758 (G-H) were expressed in both the neuronal (arrows) and the glial (arrowheads) tumour components; Panels D and I show expression of miR-519d (D) and miR-4758 (I) in neurons (NeuN-positive, red); panels E and J show expression of miR-519d (E) and miR-4758 (J) in astrocytes (GFAP-positive, red). GG: ganglioglioma. Scale bar in A: 100 μm in A-B and F-G, 50 μm in C and
H; scale bar in D: 50 μm in D-E and I-J.
(r=0.731, p=0.0002). We also evaluated the expression of both miRNAs in GG compared to other gliomas, including PA (n=15), diffuse astrocytoma grade II (AII; n=10), diffuse astrocytoma grade III (AIII; n=14) and glioblastoma (GB; n=15; Fig. 1 A-B). miR-519d was upregulated in GG compared to all other gliomas, whereas miR-4758 was upregulated compared to AII, AIII, GB but not PA. Furthermore, no difference was found in expression of both miRNAs in BRAFV600E mutated GGs (n=8) compared to wildtype GGs (n=6; p=0.950 and p=0.414; data not shown).
miR-519d and miR-4758 expression by quantitative real-time PCR in GG, DNT and subependymal giant cell astrocytoma
Recent studies indicate a robust stability of miRNAs, supporting the accuracy of miRNA measurements with quantitative real-time PCR, also in formalin-fixed paraffin-embedded (FFPE) tissues 30,35,36. Therefore, miR-519d and miR-4758 expression was also evaluated in a large cohort of FFPE samples, including control cortex (n=9), GG (n=14), peritumoural cortex (n=7), DNT (n=9) and subependymal giant cell astrocytoma (SEGA; n=10) samples. Normal appearing peritumoural tissue represents appropiate disease control tissue for GG, since it
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