Page 164 - Molecular features of low-grade developmental brain tumours

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is exposed to the same seizure activity, drugs and fixation time, while also being of identical age and gender. Evaluation of miR-519d and miR-4758 expression in this cohort confirmed the upregulation of miR-519d in GG compared to control cortex (p=0.041), DNT, SEGA and peritumoural cortex, whereas miR4768 was upregulated in GG compared to control cortex (p=0.035), DNT and SEGA but not when compared to peritumoural cortex (Fig. 1 C-D).
Figure 3. Relative expression of miR-519d and miR-4758 target genes in ganglioglioma. Quantitative real-time PCR of ERBB3, AKT3, PI3KCA, RB1, PTEN, TP53, CDKN1B, ERBB4, JAK1, CDKN1A, TIMP2, CDK4, CDK2 and MDM2 in GG (n=14, except for ERBB4 where n=13) compared to control cortex (n=7). Panel A shows increased mRNA expression of ERBB4, JAK1 and CDKN1A and decreased mRNA expression of ERBB3, AKT3, PI3KCA, RB1, PTEN, TP53 and CDKN1B in GG compared to control cortex. The expression of TIMP2, CDK4, CDK2 and MDM2 did not change. Data are expressed relative to the expression observed in control cortex. mRNA expression was normalized to that of EF1α. Dots represent individual samples. The error bars represent SEM; statistical significance: *p < 0.05; **p < 0.01, ***p < 0.001, Kruskal–Wallis test followed by Mann-Whitney U test. ctx: control cortex. GG: ganglioglioma. Panel B shows a schematic overview of the PI3K pathway. The red arrows indicate the upregulation of genes and the blue arrows
the downregulation of genes as indicated in panel A.
miR-519d and miR-4758 cellular distribution by in situ hybridization in GG
The cellular distribution of miR-519d and miR-4758 in peritumoural tissue (n=6) and GG (n=7) was investigated using in situ hybridization (ISH). In peritumoural tissue a weak expression of miR-519d and miR-4758 was observed in neuronal cells, but could not be detected in glial cells (Fig. 2A and F). Expression of both miR-519d and miR-4758 was found specifically in cells with atypical astroglia morphology and in dysplastic neurons (Fig. 2B-C and G-H). Double labelling confirmed miR-519d and miR-4758 expression in NeuN-positive neurons and GFAP-positive astrocytes in GG (Fig. 2D-E and I-J).
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