Homo sapiens
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PROVIDER: PRJNA98051 | ENA |
REPOSITORIES: ENA
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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.
2008-03-10 | GSE7330 | GEO
Project description:Glioblastoma multiforme (GBM) is a highly lethal brain tumor. Due to resistance to current therapies, patient prognosis remains poor and development of novel and effective GBM therapy is crucial. Glioma stem cells (GSCs) have gained attention as therapeutic target in GBM due to their relative resistance to current therapies and potent tumor-initiating ability. Recent studies including our own identified that the mitotic kinase, maternal embryonic leucine-zipper kinase (MELK), is highly expressed in GBM tissues, specifically in GSCs, and its expression is inversely correlated with the post-surgical survival period of GBM patients. In addition, patient-derived GSCs depend on MELK for their survival and growth both in vitro and in vivo. Here, we provide evidence that the kinase activity of MELK is essential for the action of MELK in GSCs and vital for GBM growth. We utilized in silico structure-based analysis for protein-compound interaction to predict that a recently identified small molecule, Compound 1 (C1), binds to the kinase-active site of MELK protein and eliminates MELK kinase activity in nanomolar concentrations. When treated with C1, GSCs undergo mitotic arrest and subsequent cellular apoptosis in vitro, a phenotype identical to that observed using MELK shRNA-mediated knockdown. C1 treatment strongly induces tumor cell apoptosis in slice cultures of GBM surgical specimens and attenuates growth of mouse intracranial tumors derived from GSCs in a dose-dependent manner. Lastly, C1 treatment sensitizes GSCs to radiation treatment. Collectively, these data indicate that targeting MELK kinase activity is a promising approach to attenuate GBM growth by eliminating GSCs in tumors. Microarray-based expression analysis of glioma stem cells treated with MELK-signaling inhibitors
2013-08-28 | E-GEOD-50227 | biostudies-arrayexpress
Project description:Glioblastoma multiforme (GBM) is a highly lethal brain tumor. Due to resistance to current therapies, patient prognosis remains poor and development of novel and effective GBM therapy is crucial. Glioma stem cells (GSCs) have gained attention as therapeutic target in GBM due to their relative resistance to current therapies and potent tumor-initiating ability. Recent studies including our own identified that the mitotic kinase, maternal embryonic leucine-zipper kinase (MELK), is highly expressed in GBM tissues, specifically in GSCs, and its expression is inversely correlated with the post-surgical survival period of GBM patients. In addition, patient-derived GSCs depend on MELK for their survival and growth both in vitro and in vivo. Here, we provide evidence that the kinase activity of MELK is essential for the action of MELK in GSCs and vital for GBM growth. We utilized in silico structure-based analysis for protein-compound interaction to predict that a recently identified small molecule, Compound 1 (C1), binds to the kinase-active site of MELK protein and eliminates MELK kinase activity in nanomolar concentrations. When treated with C1, GSCs undergo mitotic arrest and subsequent cellular apoptosis in vitro, a phenotype identical to that observed using MELK shRNA-mediated knockdown. C1 treatment strongly induces tumor cell apoptosis in slice cultures of GBM surgical specimens and attenuates growth of mouse intracranial tumors derived from GSCs in a dose-dependent manner. Lastly, C1 treatment sensitizes GSCs to radiation treatment. Collectively, these data indicate that targeting MELK kinase activity is a promising approach to attenuate GBM growth by eliminating GSCs in tumors.
2013-08-28 | GSE50227 | GEO
Project description:Astrocytomas are heterogeneous intracranial glial neoplasms ranging from the highly aggressive malignant glioblastoma multiforme (GBM) to the indolent, low-grade pilocytic astrocytoma. We have investigated whether DNA microarrays can identify gene expression differences between high-grade and low-grade glial tumors. We compared the transcriptional profile of 45 astrocytic tumors including 21 GBMs and 19 pilocytic astrocytomas using oligonucleotide-based microarrays. Of the approximately 6800 genes that were analyzed, a set of 360 genes provided a molecular signature that distinguished between GBMs and pilocytic astrocytomas. Many transcripts that were increased in GBM were not previously associated with gliomas and were found to encode proteins with properties that suggest their involvement in cell proliferation or cell migration. Microarray-based data for a subset of genes was validated using real-time quantitative reverse transcription-PCR. Immunohistochemical analysis also localized the protein products of specific genes of interest to the neoplastic cells of high-grade astrocytomas. Our study has identified a large number of novel genes with distinct expression patterns in high-grade and low-grade gliomas.
2015-06-25 | GSE70231 | GEO
Project description:Astrocytomas are heterogeneous intracranial glial neoplasms ranging from the highly aggressive malignant glioblastoma multiforme (GBM) to the indolent, low-grade pilocytic astrocytoma. We have investigated whether DNA microarrays can identify gene expression differences between high-grade and low-grade glial tumors. We compared the transcriptional profile of 45 astrocytic tumors including 21 GBMs and 19 pilocytic astrocytomas using oligonucleotide-based microarrays. Of the approximately 6800 genes that were analyzed, a set of 360 genes provided a molecular signature that distinguished between GBMs and pilocytic astrocytomas. Many transcripts that were increased in GBM were not previously associated with gliomas and were found to encode proteins with properties that suggest their involvement in cell proliferation or cell migration. Microarray-based data for a subset of genes was validated using real-time quantitative reverse transcription-PCR. Immunohistochemical analysis also localized the protein products of specific genes of interest to the neoplastic cells of high-grade astrocytomas. Our study has identified a large number of novel genes with distinct expression patterns in high-grade and low-grade gliomas. hanas-00078 Assay Type: Gene Expression Provider: Affymetrix Array Designs: Hu6800 Organism: Homo sapiens (ncbitax) Tissue Sites: Brain Material Types: synthetic_DNA, synthetic_RNA, organism_part Disease States: Primary Glioma, Normal
2015-06-25 | E-GEOD-70231 | biostudies-arrayexpress
Project description:Maternal embryonic leucine zipper kinase (MELK) has been implicated in cell-cycle regulation, yet its transcriptional programs in megakaryocytic cells remain incompletely defined. To profile MELK-dependent gene expression changes, we performed bulk RNA-seq on the human megakaryoblastic cell line MEG-01 transduced with a control pLKO.1 vector or a MELK-targeting shRNA (sh2-MELK), with three independent biological replicates per condition. Paired-end sequencing reads (raw FASTQ files) and processed gene-level expression quantifications are provided to support differential expression and pathway analyses of MELK knockdown in megakaryocytic cells.
2026-04-02 | GSE322507 | GEO
Project description:To investigate the mechanism by which Maternal Embryonic Leucine Zipper Kinase (MELK) regulates the actin cytoskeleton and affects coronavirus infections, we performed an Immunoprecipitation-Mass Spectrometry (IP-MS) assay. The goal was to identify specific actin-binding proteins that interact with MELK. This dataset contains the identification of proteins co-immunoprecipitated with FLAG-tagged MELK compared to an Empty Vector (EV) control in HEK293T cells .
2026-04-01 | PXD057095 | Pride
Project description:Maternal Embryonic Leucine Zipper Kinase (MELK), a Ser/Thr protein kinase, is highly over expressed in stem and cancer cells. The oncogenic role of MELK is attributed to its capacity to disable critical cell cycle checkpoints and to enhance replication. Most functional studies have relied on the use of siRNA/shRNA-mediated gene silencing, but this is often compromised by off target effects. Here we present the cellular validation of a novel, potent and selective small molecule MELK inhibitor, MELK-T1, which has enabled us to explore the biological function of MELK. Strikingly, the binding of MELK-T1 to endogenous MELK triggers a rapid and proteasome dependent degradation of the MELK protein. Treatment of MCF-7 breast adenocarcinoma cells with MELK-T1 leads to an accumulation of stalled replication forks and double strand breaks, followed by a replicative senescence phenotype. This phenotype correlates with a rapid and long-lasting ATM activation and phosphorylation of CHK2. Furthermore, MELK-T1 induces strong phosphorylation of p53 and prolonged up-regulation of p21. Our data generated with MELK-T1 indicate that MELK is a key stimulator of proliferation by its ability to increase the threshold for DNA damage tolerance. Thus, targeting MELK by combined inhibition of its catalytic function and inhibitor-induced degradation might sensitize tumors to DNA-damaging agents or radiation therapy, by lowering the DNA damage threshold.
2015-12-11 | GSE62477 | GEO
Project description:Paediatric low-grade gliomas (LGGs) account for about a third of all brain tumours in children. We conducted a detailed study of DNA methylation to improve our understanding of the biology of pilocytic and diffuse astrocytomas. Comparisons were performed between tumours and normal brain controls from matching location, and between pilocytic and diffuse astrocytomas. Pilocytic astrocytomas were found to have a distinctive signature involving 315 CpG sites, with the majority of the sites (312 CpG sites) hypomethylated in pilocytic astrocytomas. Additionally many of the sites were located within annotated enhancers. The distinct signature in pilocytic astrocytomas was not present in diffuse astrocytomas or in published profiles of other brain tumours and normal brain tissue. On further analysis of the 315 CpG sites, the AP-1 transcription factor complex was predicted to bind within 200bp of a subset of teh 315 differentially methylated CpG sites. We also observed up-regulation of the AP-1 factors, FOS and FOSL1 in pilocytic astrocytomas. Our findings highlight novel epigenetic differences between pilocytic and diffuse astrocytomas, in addition to well-described alterations involving BRAF, MYB and FGFR1.
2016-05-10 | GSE77241 | GEO
Project description:Triple-negative breast cancer (TNBC) has high relapse and metastasis rates and a high proportion of cancer stem-like cells (CSCs), which possess self-renewal and tumor initiation capacity. MELK (maternal embryonic leucine zipper kinase), a protein kinase of the Snf1/AMPK kinase family, is known to promote CSC maintenance and malignant transformation. Our study showed that MELK knockdown using siRNA or MELK inhibition using the MELK inhibitor MELK-In-17 significantly reduced invasiveness, reversed epithelial-to-mesenchymal transition (EMT), and reduced CSC self-renewal and maintenance in TNBC cells. Nude mice injected with CRISPR MELK-knockout MDA-MB-231 cells exhibited suppression of lung metastasis and improved overall survival compared with mice injected with control cells. Furthermore, MELK-In-17 suppressed 4T1 tumor growth in syngeneic BALB/c mice. Our findings indicate that MELK supports metastasis by promoting EMT and the CSC phenotype in TNBC. In our microarray analysis, we identified potential downstream targets of MELK, including STAT5 and NF-kB target genes, as well as genes involved in tumor progression and metastasis (i.e., EMT, angiogenesis, hypoxia, and apical junction). EMT was the most strongly enriched hallmark among genes highly expressed in Cas9-p15 control cells, further confirming that EMT is a major factor contributing to MELK-induced metastasis in TNBC. We also identified a direct physical interaction partner (PRKAB2) of MELK and a set of intermediate proteins (CDC25B, EZH2, FOXM1, JUN, MAP3K5, PRKAB1, PRKAB2, and SMAD2), suggesting that these proteins are key components of MELK-induced signal transduction.
2023-05-01 | GSE227774 | GEO