CNSC-03. HIGH EXPRESSION OF PICCOLO AND SYNTAXIN-1A IN PAEDIATRIC MEDULLOBLASTOMA DUE TO BOTH: HIGH NEURONAL FRACTION AND ENDOGENOUS EXPRESSION

Abstract Emerging evidence indicates that the “healthy” nervous system contributes to the pathogenesis of cancer. Tumor cells were found to form ultra-long protrusions with distinct synapses, mainly in the infiltrative zone, resulting in a neuron-to-brain tumor synaptic communication. Located at the presynapse, proteins of the cytomatrix of the active zone have been identified to maintain highly specialized functions in neurons. Further, the proteins were shown to be involved in progression in various tumors, but little is known about their role in brain tumors. This study examined the expression of CAZ proteins in glioma and medulloblastoma. Tumor samples of Astrocytoma, glioblastoma, pilocytic astrocytoma and medulloblastoma were obtained during neurosurgical resection. Transcription rate of following CAZ proteins was measured via qPCR: SNAP25, VAMP1, VAMP2, SYT1, PCLO, BSN, STX1A. To examine amount of neuronal tissue TUBB3 and for glial fraction GFAP were quantified. A medulloblastoma cell line (DAOY) was furthermore analyzed to evaluate origin of high expressed proteins. Medulloblastoma showed high expression of PCLO (pilocytic astrocytoma vs. medulloblastoma p=0.0126) and STX1A (pilocytic astrocytoma vs. medulloblastoma p=0.0006) compared to. Likewise a high transcriptional level of TUBB3 could be seen with significance to pilocytic astrocytoma (2.2 ± 1.4 vs. 0.2 ± 0.17; p = 0.0018), which could indicate a high amount of neuronal tissue in given medulloblastoma samples. To rule out a causal link between high proportion of neuronal tissue and high CAZ expression, a paediatric medulloblastoma cell line was analysed. High expression of PCLO and STX1A in absence of TUBB3 was shown (3.8 and 2.01 vs. 0.059), indicating endogenous expression of CAZ proteins in medulloblastoma.