RFLP and microsatellite analysis with 23 polymorphic markers spanning the entire long arm of chromosome 14 in 108 neuroblastomas showed allelic loss in 19 out of 107 (18%) informative tumors, placing 14q among the most frequently affected chromosomal regions in neuroblastoma. One minimal deletion re
Assessment of NORE1A as a putative tumor suppressor in human neuroblastoma
✍ Scribed by Janos Geli; Per Kogner; Fredrik Lanner; Natalia Natalishvili; Christofer Juhlin; Nimrod Kiss; Geoffrey J. Clark; Tomas J. Ekström; Filip Farnebo; Catharina Larsson
- Publisher
- John Wiley and Sons
- Year
- 2008
- Tongue
- French
- Weight
- 250 KB
- Volume
- 123
- Category
- Article
- ISSN
- 0020-7136
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✦ Synopsis
Abstract
The putative tumor suppressor NORE1A (RASSF5) is a member of the Ras association domain family and is commonly inactivated in human cancer. The closely related gene family member and functional collaborator RASSF1A is a bona fide tumor suppressor and is frequently involved in neuroblastoma. In the present study, we sought to investigate the role of NORE1A in human neuroblastoma. A panel of tumors (36 neuroblastomas and 4 ganglioneuromas) and neuroblastoma cell lines was assessed for NORE1A gene expression by Taqman quantitative RT‐PCR. Promoter methylation was quantitatively determined by methylation sensitive pyrosequencing. The antitumourigenic role was functionally investigated in Nore1a transfected SK‐N‐BE (2) cells by fluorescent inhibition of caspase activity and BrdU incorporation assays. Neuroblastoma cells showed very low or absent NORE1A mRNA expression, which could not be reversed by trichostatin A or 5‐aza‐cytidine treatments. Neuroblastoma tumors showed suppressed NORE1A gene expression that was particularly pronounced in cases without MYCN amplification or 1p loss. Methylation of the NORE1A promoter was not observed in primary tumors and only one out of seven neuroblastoma cell lines displayed weak partial methylation. Transient expression of Nore1a resulted in enhanced apoptosis and delayed cell cycle progression. In conclusion NORE1A appears to be strongly suppressed in neuroblastic tumors and reconstitution of its expression diminishes the tumorigenic phenotype. Promotor methylation is not a common mechanism responsible for NORE1A transcriptional suppression in this tumor type. © 2008 Wiley‐Liss, Inc.
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