Dataset Information

Neuralized1 causes apoptosis and downregulates Notch target genes in medulloblastoma.

ABSTRACT: Neuralized (Neurl) is a highly conserved E3 ubiquitin ligase, which in Drosophila acts upon Notch ligands to regulate Notch pathway signaling. Human Neuralized1 (NEURL1) was investigated as a potential tumor suppressor in medulloblastoma (MB). The gene is located at 10q25.1, a region demonstrating frequent loss of heterozygosity in tumors. In addition, prior publications have shown that the Notch pathway is functional in a proportion of MB tumors and that Neurl1 is only expressed in differentiated cells in the developing cerebellum. In this study, NEURL1 expression was downregulated in MB compared with normal cerebellar tissue, with the lowest levels of expression in hedgehog-activated tumors. Control of gene expression by histone modification was implicated mechanistically; loss of 10q, sequence mutation, and promoter hypermethylation did not play major roles. NEURL1-transfected MB cell lines demonstrated decreased population growth, colony-forming ability, tumor sphere formation, and xenograft growth compared with controls, and a significant increase in apoptosis was seen on cell cycle and cell death analysis. Notch pathway inhibition occurred on the exogenous expression of NEURL1, as shown by decreased expression of the Notch ligand, Jagged1, and the target genes, HES1 and HEY1. From these studies, we conclude that NEURL1 is a candidate tumor suppressor in MB, at least in part through its effects on the Notch pathway.

SUBMITTER: Teider N

PROVIDER: S-EPMC3018940 | biostudies-literature | 2010 Dec

REPOSITORIES: biostudies-literature

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Neuralized1 causes apoptosis and downregulates Notch target genes in medulloblastoma.

Teider Natalia N Scott Deborah K DK Neiss Adrianne A Weeraratne S Dilhan SD Amani Vladimir M VM Wang Yifei Y Marquez Victor E VE Cho Yoon-Jae YJ Pomeroy Scott L SL

Neuro-oncology 20100916 12

Neuralized (Neurl) is a highly conserved E3 ubiquitin ligase, which in Drosophila acts upon Notch ligands to regulate Notch pathway signaling. Human Neuralized1 (NEURL1) was investigated as a potential tumor suppressor in medulloblastoma (MB). The gene is located at 10q25.1, a region demonstrating frequent loss of heterozygosity in tumors. In addition, prior publications have shown that the Notch pathway is functional in a proportion of MB tumors and that Neurl1 is only expressed in differentiat ...[more]

PMID: 20847082

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Project description:BackgroundMedulloblastoma is the most common malignant brain tumor of childhood. Children who relapse usually die of their disease, which reflects resistance to radiation and/or chemotherapy. Improvements in outcome require a better understanding of the molecular basis of medulloblastoma growth and treatment response. TP73 is a member of the TP53 tumor suppressor gene family that has been found to be overexpressed in a variety of tumors and mediates apoptotic responses to genotoxic stress. In this study, we assessed expression of TP73 RNA species in patient tumor specimens and in medulloblastoma cell lines, and manipulated expression of full-length TAp73 and amino-terminal truncated DeltaNp73 to assess their effects on growth.MethodsWe analyzed medulloblastoma samples from thirty-four pediatric patients and the established medulloblastoma cell lines, Daoy and D283MED, for expression of TP73 RNA including the full-length transcript and the 5'-terminal variants that encode the DeltaNp73 isoform, as well as TP53 RNA using quantitative real time-RTPCR. Protein expression of TAp73 and DeltaNp73 was quantitated with immunoblotting methods. Clinical outcome was analyzed based on TP73 RNA and p53 protein expression. To determine effects of overexpression or knock-down of TAp73 and DeltaNp73 on cell cycle and apoptosis, we analyzed transiently transfected medulloblastoma cell lines with flow cytometric and TUNEL methods.ResultsPatient medulloblastoma samples and cell lines expressed full-length and 5'-terminal variant TP73 RNA species in 100-fold excess compared to non-neoplastic brain controls. Western immunoblot analysis confirmed their elevated levels of TAp73 and amino-terminal truncated DeltaNp73 proteins. Kaplan-Meier analysis revealed trends toward favorable overall and progression-free survival of patients whose tumors display TAp73 RNA overexpression. Overexpression of TAp73 or DeltaNp73 induced apoptosis under basal growth conditions in vitro and sensitized them to cell death in response to chemotherapeutic agents.ConclusionThese results indicate that primary medulloblastomas express significant levels of TP73 isoforms, and suggest that they can modulate the survival and genotoxic responsiveness of medulloblastomas cells.

Dataset Information

Neuralized1 causes apoptosis and downregulates Notch target genes in medulloblastoma.

Publications

Neuralized1 causes apoptosis and downregulates Notch target genes in medulloblastoma.

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