miR-139-5p targeting DNMT1 inhibits the growth and metastasis of glioblastoma / 西安交通大学学报(医学版)

【Objective】 To investigate the expression and biological role of miR-139-5p in glioblastoma and the regulatory effect of miR-139-5p on DNA methyltransferase 1 (DNMT1). 【Methods】 qRT-PCR was used to detect the expression of miR-139-5p in glioblastoma tumor tissue, paired paracancerous tissue, human normal glioma cell line HEB, and human glioma cell line U251. The expression of miR-139-5p in U251 cells was up-regulated by transfection of miR-139-5p mimetics, and the expression of DNMT1 was down-regulated by transfection of DNMT1-targeted siRNA (DNMT1-siRNA). The expression of DNMT1 and neurofibromatosis type 2 (NF2) in tissues and cells was detected by qRT-PCR, Western blotting, immunohistochemistry and immunofluorescence. The cell counting kit-8 (CCK-8), flow cytometry and Matrigel Transwell were used to evaluate the proliferation, apoptosis and invasion ability of U251 cells. 【Results】 Compared with paracancerous tissues or HEB cells, miR-139-5p expression in glioblastoma tissues and U251 cells was suppressed (P<0.05). Compared with control cells, transfection of miR-139-5p mimic significantly down-regulated the expression of DNMT1 and up-regulated the expression of NF2 (P<0.05). Compared with control cells, transfection of DNMT1-siRNA significantly promoted the expression of NF2 (P<0.05). Transfection of miR-139-5p mimetics or DNMT1-siRNA significantly induced U251 cell apoptosis and inhibited cell invasion (P<0.05). 【Conclusion】 miR-139-5p plays an anti-cancer role in glioblastoma, and it inhibits tumor proliferation and metastasis by targeting negative regulation of DNMT1.

The Similarities and Differences between Intracranial and Spinal Ependymomas : A Review from a Genetic Research Perspective

Ependymomas occur in both the brain and spine. The prognosis of these tumors sometimes differs for different locations. The genetic landscape of ependymoma is very heterogeneous despite the similarity of histopathologic findings. In this review, we describe the genetic differences between spinal ependymomas and their intracranial counterparts to better understand their prognosis. From the literature review, many studies have reported that spinal cord ependymoma might be associated with NF2 mutation, NEFL overexpression, Merlin loss, and 9q gain. In myxopapillary ependymoma, NEFL and HOXB13 overexpression were reported to be associated. Prior studies have identified HIC-1 methylation, 4.1B deletion, and 4.1R loss as common features in intracranial ependymoma. Supratentorial ependymoma is usually characterized by NOTCH-1 mutation and p75 expression. TNC mutation, no hypermethylation of RASSF1A, and GFAP/NeuN expression may be diagnostic clues of posterior fossa ependymoma. Although MEN1, TP53, and PTEN mutations are rarely reported in ependymoma, they may be related to a poor prognosis, such as recurrence or metastasis. Spinal ependymoma has been found to be quite different from intracranial ependymoma in genetic studies, and the favorable prognosis in spinal ependymoma may be the result of the genetic differences. A more detailed understanding of these various genetic aberrations may enable the identification of more specific prognostic markers as well as the development of customized targeted therapies.

Molecular Characterization of the NF2 Gene in Korean Patients with Neurofibromatosis Type 2: A Report of Four Novel Mutations / 대한진단검사의학회지

BACKGROUND: Neurofibromatosis type 2 (NF2) is an autosomal dominant syndrome caused by the NF2 tumor suppressor gene. However, the NF2 mutation characteristics in Korean patients are not sufficiently understood. In this study, we conducted a comprehensive mutational analysis in 7 Korean NF2 patients by performing direct sequencing and gene-dosage assessment. METHODS: We analyzed all exons and flanking regions of NF2 by direct sequencing and screened the deletions or duplications involving NF2 by multiplex ligation-dependent probe amplification. RESULTS: Four novel NF2 mutations, including 2 splice-site mutations (c.364-1G>A and c.886-3C>G), 1 frameshift mutation (c.524delA), and 1 missense mutation (c.397T>C; p.Cys133Arg), were identified in our patients. No large deletion or duplication was identified in our series. Subsequently, we identified an abnormal splicing product by using reverse transcription-PCR and direct sequencing in 2 patients with a novel splice-site mutation. The missense mutation c.397T>C was predicted to have harmful effects on protein function. CONCLUSIONS: The detection rate of NF2 mutations in Korean patients (57%) is similar to those in other populations. Our results provided a greater insight into the mutational spectrum of the NF2 gene in Korean subjects.

Construction of eukaryotic expression vectors of two NF2 mutants and their expression in rat schwannoma cell line / 第二军医大学学报

Objective: To construct the eukaryotic expression vectors of two NF2 mutants (neurofibromatosis II) and to study their expression in rat schwannoma cell line (RT4). Methods: Site-directed mutagenesis was performed to induce the mutation of the codons for the residue Lys42 in NF2 into Pro in pcDNA3. 1-NF2ΔLys42Pro, and convert the codons for Phe 47 into that of Leu. RT4 cells were transiently transfected with the 3 kinds of plasmids containing the mutations and wide-type NF2 via lipofectin separately, then the expression levels of NF2 mRNA and protein were determined by RT-PCR and Western blotting in 3 groups. The cell proliferation was determined by the MTT after transfection. Results: DNA sequence analysis demonstrated the two-step mutagenesis was successful and the two plasmids of pcDNA3.1ΔLys42Pro and pcDNA3.1-NF2ΔPhe47Leu were obtained, both of the transfectants could produce merlin protein and mRNA. The two mutants had a significantly lower inhibitory rate for RT4 cells compared with wide-type NF2 (P < 0.05). Conclusion: The recombinant plasmids pcDNA3. 1-NF2ΔLys42Pro and pcDNA3. 1-NF2ΔPhe47Leu have been successfully constructed and they can be efficiently expressed in RT4 cells.

Merlin Represses Ras-Induced Cyclin D1 Transcription through the Cyclic AMP-Responsive Element

Mutations in the NF2 tumor suppressor gene cause neurofibromatosis type 2, an autosomal dominant inherited syndrome predisposed to the multiple tumors of the nervous system. Merlin, the NF2 gene product was reported to block Ras-mediated cell transformation and represses Ras-induced expression of cyclin D1. However, the potential mechanism underlying the anti-Ras function of merlin on the cyclin D1 is still unclear. In this study, we investigated whether merlin decreases Ha-ras-induced accumulation of cyclin D1 at the transcriptional level, and demonstrated that merlin suppressed Ras-induced cyclin D1 promoter activity mediated by the cyclic AMP-responsive element (CRE) in SK-N-BE (2) C neuroblastoma cells. Furthermore, we found that merlin attenuated active Ras and forskolin-induced CRE-driven promoter activity. These results suggest that the transcriptional repression of the cyclin D1 expression by merlin may contribute to the inhibition of Ras-induced cell proliferation

Germline Mutations of the NF2 Gene in Korean Neurofibromatosis 2 Patient / 대한암학회지

PURPOSE: Neurofibromatosis 2(NF2) is an autosomal dominant disease characterized by development of bilateral acoustic neuroma and various central nervous system tumors such as meningiomas, ependymomas, and schwannomas. Recent cloning of the gene responsible for NF2, the NF2 gene, permits the presymptomatic genetic diagnosis of affected individuals by direct analysis of the gene. This paper was intended to identify germline mutations in Korean NF2 patients. MATERIALS AND METHODS: We collected blood samples from 15 clinically diagnosed NF2 patients treated at the Department of Neurosurgery, Seoul National University Hospital. Purified genomic DNA samples were analyzed for mutations of the NF2 gene by using polymerase chain reaction(PCR)-single strand conformation polymorphism(SSCP) method followed by direct DNA sequencing. RESULTS: We were able to identify germline mutation of the NF2 gene in one patient. The mutation identified was 1 base pair deletion(A) at codon 318, resulting in premature stop codon due to frameshift. CONCLUSION: Identification of the germline mutation in NF2 gene should enable us to test all individual family members at risk to determine whether or not they carry the mutant NF2 gene.