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Real-time quantitative PCR analysis of human astrocytomas

ABSTRACT: Pediatric astrocytomas, a leading cause of death associated with cancer, are the most common primary central nervous system tumors found in children. Most studies of these tumors focus on adults, not children. We examined the global protein and microRNAs expression pattern by 2D SDS-PAGE, mass spectrometry (MALDI-TOF) and RT2 miRNA PCR Array System. MicroRNAs analysis revealed for the first time novel microRNAs involved in astrocytomas biology. Interestingly, miR-138 and miR-145 down-regulation appear to be associated with protein over-expression of vimentin and Bax, respectively. In conclusion, our results show that novel proteins and microRNAs altered on pediatric astrocytoma could serve as biomarkers to distinguish between astrocytoma grades. Astrocytoma samples were colected from patients and total RNA isolation (30 mg of tissue) was performed using the TRIzol® protocol (Invitrogen, USA) according to the manufacturer′s instructions. Samples were analyzed using SA Biosciences RT2 miRNA PCRArray System to determied the miRNA expression between control samples and tumors

ORGANISM(S): Homo sapiens

PROVIDER: GSE44280 | GEO | 2013/02/12

SECONDARY ACCESSION(S): PRJNA189282

REPOSITORIES: GEO

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Project description:Purpose: Gene expression analyses comparing tumors of different behaviors have been used for the identification of genes that have a role in the growth and maintenance of tumors, with the aim of both understanding the molecular basis of tumorigenesis and identifying novel potential therapeutic targets. We have here used this approach to identify the underlying gene expression differences between highly invasive glioblastoma multiforme and typically benign pilocytic astrocytomas. Experimental Design: We performed cDNA microarray analyses comparing astrocytomas of polar grade: grade I, pilocytic astrocytoma (PA), the non-invasive and most frequent pediatric tumor, with grade IV, the highly infiltrative glioblastoma multiforme (GBM) Results: Despite the significant clinical and pathological differences between the two tumor types, only 63 genes were found to exhibit two-fold or greater over-expression in GBM as compared with PA. A functional classification of the GBM over-expressed genes indicated that more than 50% are related to the regulation of the cell cycle and mitosis. Microarray data was validated by RQ-PCR testing six over-expressed genes in GBM related to PA: MELK, AUKB, ASPM, PRC1, IL13RA2 and KIAA0101. The differential expression was confirmed for all six genes, showing at least a 5 fold increase in the average expression levels in GBM compared to PA. Of the over expressed genes, that which exhibited the most statistically significant difference is Maternal Embryonic Leucine zipper Kinase (MELK). We undertook a more detailed investigation of the expression of this serine/threonine kinase gene in astrocytomas in the light of its role in the regulation of multipotent neural progenitor proliferation and previous suggestions that this may be a oncogenic target of general importance. In an examination of more than 100 tumors of the central nervous system we found progressively higher expression of MELK in GBM with astrocytoma grade and a noteworthy uniformity of high level expression in GBM. This latter feature probably explains the lack of observed association of MELK expression with survival of GBM patients. Over-expression at a similar level to GBM was also observed in medulloblastoma. We found neither gene methylation nor amplification to be a factor in MELK expression but were able to demonstrate that MELK knockdown in malignant astrocytoma cell lines caused a reduction in proliferation and anchorage-independent growth in in vitro assays. Conclusions: Our results indicate that GBM and PA differ by the expression of surprisingly few genes. Among them, MELK may play a key role in differentiating these two tumor types and represent an important therapeutic target for the management of the most frequent brain tumors in adult and children. Keywords: Comparizon of CNS tumors of different grades.

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Real-time quantitative PCR analysis of human astrocytomas

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