Gene expression of dab1 and p35 was determined by real-time RT-PCR (reverse transcriptase polymerase chain reaction) in gangliogliomas (n = 14) vs. non-neoplastic central nervous system tissue (n = 20).
Recent data suggest several components of the insulin-pathway, including TSC1 and TSC2 mutated in tuberous sclerosis complex (TSC), to be altered in gangliogliomas and FCD with Taylor type balloon cells (FCD(IIb)).
A polymorphism in the TSC2 gene has been found to be increased in gangliogliomas, a lesion which is associated with disturbed neuro-glial cell migration pattern.
SSCP analysis revealed an allelic variant of TSC2 to be significantly increased (exon 41: 50.0% vs controls 14%, P=0.0132), which previously was reported to be increased in gangliogliomas and mineralized focal cortical dysplasia as well.
The authors report here the first unequivocal case of a ganglioglioma harboring aberrant TP53 product that was expressed predominantly in the neuronal component.
The authors report here the first unequivocal case of a ganglioglioma harboring aberrant TP53 product that was expressed predominantly in the neuronal component.
The present case is unusual in four aspects: (i) it arose from a low-grade ganglioglioma in the absence of previous radiation or chemotherapy, which is the fourth reported case; (ii) the original tumor showed a high proliferative index on flow cytometry but a low Ki-67 labeling index, implying that the application of flow cytometry might play a certain role in predicting biological and clinical behavior of low grade gangliogliomas; (iii) p53 mutation and deletion appeared in the secondary glioblastoma, which was not shown in the original well-differentiated ganglioglioma; and (iv) the transformed glioblastoma showed p16 inactivation detected by methylation and deletion, which are relatively uncommon genetic events in secondary glioblastomas.
Findings demonstrate that the presence of TP53 mutation in progressed gangliogliomas should be interpreted as a progression-associated mutation rather than a consequence of treatment.
Direct analysis demonstrated loss of p19 expression and p53 mutation in the malignant areas, highly suggestive of these alterations being involved in the malignant progression of the ganglioglioma.
Importantly, this case contradicts previous reports of p53 and BRAF mutations portending worsened tumor behavior and prognosis and demonstrates that further studies are needed to delineate the role of genetic characterization in the biologic understanding and management of gangliogliomas.
In both GGs and DNTs, the presence of BRAF V600E mutation was significantly associated with the expression of CD34, phosphorylated ribosomal S6 protein (pS6; marker of mTOR pathway activation) in dysplastic neurons and synaptophysin (P < 0.05).
In both GGs and DNTs, the presence of BRAF V600E mutation was significantly associated with the expression of CD34, phosphorylated ribosomal S6 protein (pS6; marker of mTOR pathway activation) in dysplastic neurons and synaptophysin (P < 0.05).
Since the LKB1 gene is expressed in the fetal and adult brain, our data would suggest its likely involvement in the pathogenesis of a subset of gangliogliomas.
There are several reported cases of AT/RT (or INI1-negative rhabdoid tumors) arising in the setting of other primary brain tumors (gangliogliomas, pleomorphic xanthoastrocytomas, and high-grade gliomas), but the present case
Further cases of NET-H3-G34 with dysplastic ganglion cells should be clinically followed to find differences or similarities in their biological behavior, as compared to NET-H3-G34 and anaplastic gangliogliomas.
Together, this study highlights that ganglioglioma is characterized by genetic alterations that activate the MAP kinase pathway, with only a small subset of cases that harbor additional pathogenic alterations such as CDKN2A deletion.
Activation of the MAP Kinase (MAPK) pathway caused by the BRAFV600E mutation or the KIAA1549-BRAF fusion has been reported in pediatric GG and PA, respectively.