Tumor Suppressor Gene In Gliomas Research Articles

Influence of miR -451 on biological characters of glioma cell line A172

Objective To investigate the influence of miR -451 on biological characters of gliomas cells A172. Method The oligonucleotide of miR -451 mimics was transfected into human glioblastoma cell line A172. The expression of miRNA -451 was identified by real - time PCR after transfection, and targeting protein expression was evaluated by Western blot. The cell proliferation was determined by flow cytometry and MTT assay. Moreover,cell cycle molecules were detected by Western blot analysis. Results The miR -451was markedly up -regulated after transfection of miRNA -451 mimics group. As compared with control and scramble group, the cell cycle was significantly arrested over 17.4% in G0/G1 phase by flow cytometry assay,meanwhile the protein expression of C - myc and regulatory molecules for cell cycle progression including CDK2, CDK4, Cyclin D1 and Cyclin E were all down -regulated. The proliferation was significantly decreased by the MTT assay at the same time. Conclusions MiR - 451 could inhibit the proliferation activity of A172 glioma cell. It suggests that miR -451 is a tumor suppressor gene in glioma. Key words: MicroRNA -451; Glioma; Cell proliferation; Cell cycle

The CASPR2 cell adhesion molecule functions as a tumor suppressor gene in glioma

Genomic translocations have been implicated in cancer. In this study, we performed a screen for genetic translocations in gliomas based on exon-level expression profiles. We identified a translocation in the contactin-associated protein-like 2 (CASPR2) gene, encoding a cell adhesion molecule. CASPR2 mRNA was fused to an expressed sequence tag that likely is part of the nuclear receptor coactivator 1 gene. Despite high mRNA expression levels, no CASPR2 fusion protein was detected. In a set of 25 glioblastomas and 22 oligodendrogliomas, mutation analysis identified two additional samples with genetic alterations in the CASPR2 gene and all three identified genetic alterations are likely to reduce CASPR2 protein expression levels. Methylation of the CASPR2 gene was also observed in gliomas and glioma cell lines. CASPR2-overexpressing cells showed decreased proliferation rates, likely because of an increase in apoptosis. Moreover, high CASPR2 mRNA expression level is positively correlated with survival and is an independent prognostic factor. These results indicate that CASPR2 acts as a tumor suppressor gene in glioma.

Novel PLA2G4C polymorphism as a molecular diagnostic assay for 19q loss in human gliomas.

PLA2G4C, encoding cytosolic phospholipase A2-gamma (cPLA2-gamma), is a 17-exon gene located on chromosome 19q13.3 within the putative glioma tumor suppressor gene region. Given the clinical importance of assessing 1p and 19q loss in human gliomas, the development of convenient and practical assays for detecting allelic loss is of considerable priority in neuro-oncology. We report a minisatellite polymorphism in the untranslated region of exon 1, with allelic variants that have one, two or three 27-bp repeats. The polymorphism is informative in 55.7% of a reference population, and accurately detects allelic loss of 19q in human gliomas. This novel marker offers distinct advantages for assessing 19q status in malignant gliomas. The relatively large size of the repeats allows detection of allelic variants with standard ethidium bromide-stained agarose gels and the PLA2G4C marker is the closest polymorphism to the smallest common deletion area in the putative glioma tumor suppressor gene region. These characteristics suggest that the PLA2G4C polymorphism will be a convenient and practical assay for clinical and research evaluation of 19q status in human gliomas.

Mapping of the chromosome 19 q-arm glioma tumor suppressor gene using fluorescence in situ hybridization and novel microsatellite markers.

Allelic loss of chromosome arm 19q is a frequent event in human diffuse glioma, suggesting the presence of a tumor suppressor gene. Previous loss of heterozygosity (LOH) analyses have mapped this gene to a 1.4-megabase interval, between the genetic markers D19S412 and STD. Further narrowing of this interval has been limited by the resolution of mapped polymorphic markers. In the present study, we have used genomic clones mapped to 19q as fluorescence in situ hybridization (FISH) probes to map the breakpoints of 13 gliomas with 19q13.3 deletion boundaries. In addition, we have developed three new polymorphic microsatellite markers (D19S1180, D19S1181, and D19S1182) that map between D19S412 and STD and have used these new markers to identify two gliomas with small deletions between the D19S412 and STD markers. Collectively, these data suggest that the region of common deletion may be as narrow as 150 kb and should facilitate future efforts to identify the glioma 19q tumor suppressor gene.

Mapping of the chromosome 19 q-arm glioma tumor suppressor gene using fluorescence in situ hybridization and novel microsatellite markers

Mapping of the chromosome 19 q-arm glioma tumor suppressor gene using fluorescence in situ hybridization and novel microsatellite markers

The human glia maturation factor-gamma gene: genomic structure and mutation analysis in gliomas with chromosome 19q loss

Human glia maturation factor-gamma (hGMF-gamma) is a recently identified gene that may be involved in glial differentiation, neural regeneration, and inhibition of tumor cell proliferation. The gene maps to the long arm of chromosome 19 at band q13.2, a region that is frequently deleted in human malignant gliomas and is thus suspected to harbor a glioma tumor suppressor gene. Given the putative role of hGMF-gamma in cell differentiation and proliferation and its localization to chromosome 19q13, this gene is an interesting candidate for the chromosome 19q glioma tumor suppressor gene. To evaluate this possibility, we determined the genomic structure of human hGMF-gamma and performed mutation screening in a series of 41 gliomas with and without allelic loss of chromosome 19q. Mutations were not detected, which suggests that hGMF-gamma is not the chromosome 19q glioma suppressor gene. However, the elucidation of the genomic structure of hGMF-gamma may prove useful in future investigations of hGMF-gamma in the normal adult and developing human nervous system.

Refinement and distinction of the chromosome 10p candidate tumor suppressor region in human gliomas

Our recent studies have shown that telomeric 10p is frequently deleted in both low and high grade gliomas. Other studies have shown an invariant association of erb-b amplification and loss of chromosome 10. It has not been determined whether this association was specific for a particular locus on chromosome 10. We sought to assess this by examining tumors, for both 10p loss and gene amplification. 55% of tumors showed some degree of allelic imbalance at 10p15. Amplification of erb-b, c-myc, and a mitochondrial cDNA probe, recently found to be amplified in diverse grades of gliomas was assessed. erb-b and the mitochondrial cDNA probe showed amplification in 28% of the tumors; c-myc gene was amplified in only one astrocytoma. No significant association was noted when comparing the presence of a specific amplified gene, and loss of loci on chromosome. Chromosome 10p15 shows significant loss in glial tumors, and is independent of the chromosome 10 region associated with erb-b amplification. The region at 10p15 is distinct in harboring a putative tumor suppressor gene in gliomas, and is involved earlier in the multi-step pathway to glial tumor malignancy.

ANOVA, a putative astrocytic RNA-binding protein gene that maps to chromosome 19q13.3.

Exon amplification from cosmids mapping to the glioma tumor suppressor gene candidate region on chromosome 19q13.3 yielded an exon with high homology to a portion of the NOVA1 gene, which encodes a neuron-specific RNA-binding protein recognized by the paraneoplastic syndrome antibody anti-Ri. Screening of a human brain cDNA library with this exon identified a 1.9 kb cDNA with extensive homology to NOVA1, including three nearly identical KH domains characteristic of a subtype of RNA-binding proteins. Northern blots demonstrated expression of a 2.5 kb mRNA in brain, but in no other tissues. In situ hybridization on human cerebral cortex showed mRNA expression restricted to astrocytes. We have therefore named the gene ANOVA, for astrocytic NOVA1-like gene. Southern blotting and single strand conformation polymorphism analyses did not show tumor-specific alterations of this gene in gliomas and RT-PCR studies showed expression in glioma cell lines, suggesting that ANOVA is not the chromosome 19q glioma tumor suppressor gene. Given that two cloned paraneoplastic antigens are neuronal RNA-binding proteins and that glial proteins may act as paraneoplastic antigens, the ANOVA product may be a target antigen in one of the undefined human paraneoplastic syndromes.

The BAX gene maps to the glioma candidate region at 19q13.3, but is not altered in human gliomas

The bax protein regulates apoptosis in a cellular pathway that involves both bcl-2 and p53, two molecules associated with human glioma tumorigenesis. We therefore evaluated the possibility that BAX functions as a glioma tumor suppressor gene. Somatic cell hybrid panels, fluorescence in situ hybridization and cosmid mapping localized the BAX gene to 19813.3, approximately 300 kb centromeric to HRC. Thus BAX maps to the region of chromosome 19 most frequently deleted in gliomas. Routine and pulsed-field gel electrophoresis/Southern blotting studies, however, failed to reveal large-scale deletions or rearrangements of the BAX gene in gliomas. In addition, single strand conformation polymorphism analysis of all six BAX exons and flanking intronic sequences did not disclose mutations in 20 gliomas with allelic loss of the other copy of 19q. A CIT polymorphism was detected in intron 3 and was common in the general population. Therefore, although BAX maps to the glioma candidate region on the long arm of chromosome 19, BAX is probably not the 19q glioma tumor suppressor gene.

Cloning of a Highly Conserved Human Protein Serine-Threonine Phosphatase Gene from the Glioma Candidate Region on Chromosome 19q13.3

Allelic loss studies have suggested that a glioma tumor suppressor gene resides in a 425-kb region of chromosome 19q, telomeric to D19S219 and centromeric to D19S112. Exon amplification of a cosmid contig spanning this region yielded four exons with high homology to a rat protein serine-threonine phosphatase from a cosmid approximately 100 kb telomeric to D19S219. Isolation of a near full-length cDNA from a human fetal brain cDNA library revealed a protein serine-threonine phosphatase with a tetratricopeptide motif, almost identical to human PPP5C (PP5) and highly homologous to rat PPT. Northern blotting demonstrated expression in most human tissues, including brain. Primary and cultured gliomas were studied for genetic alterations in this gene using pulsed-field gel electrophoresis, routine Southern blots, and genomic DNA- and RNA-based single-strand conformation polymorphism analysis. Genomic alterations were not detected in any of the gliomas, and all studied gliomas expressed the gene, suggesting that this phosphatase is not the putative chromosome 19q glioma tumor suppressor gene.