ABSTRACT
<p><b>OBJECTIVE</b>To investigate global genetic alterations in medulloblastoma, and to localize critical chromosomal loci with allelic imbalances associated with the development of medulloblastoma.</p><p><b>METHODS</b>A high-resolution genome-wide allelotype analysis, including 384 microsatellite markers, was performed in 12 medulloblastomas.</p><p><b>RESULTS</b>An average of 238 (62.3%) allelic imbalances were detected on all 39 autosomal arms. Non-random allelic gains or losses were detected on chromosomes 7q (58.3%), 8p (66.7%), 16q (58.3%), 17p (58.3%) and 17q (66.7%). In addition, chromosomal arms with frequencies of allelic imbalances higher than the mean percentage were identified on 3p (33.3%), 3q (33.3%), 4q (41.7%), 7p (33.3%), 8q (41.7%), 10q (41.7%), 13q (33.3%), 14q (33.3%) and 20q (33.3%). No relationship was found between the frequency of allelic imbalances and the clinical outcome of the patients.</p><p><b>CONCLUSIONS</b>A global view of the genetic alterations in medulloblastoma was provided. The allelic imbalances involving chromosomes 7q, 8p, 16q, 17p and 17q may play an important role in the pathogenesis of medulloblastoma.</p>
Subject(s)
Adolescent , Adult , Child , Child, Preschool , Female , Humans , Male , Alleles , Allelic Imbalance , Cerebellar Neoplasms , Genetics , Chromosomes, Human, Pair 16 , Chromosomes, Human, Pair 17 , Chromosomes, Human, Pair 7 , Chromosomes, Human, Pair 8 , Genotype , Medulloblastoma , Genetics , Microsatellite Repeats , GeneticsABSTRACT
<p><b>OBJECTIVE</b>To study the mechanism of antisense epidermal growth factor receptor cDNA in growth suppression of glioblastomas cells.</p><p><b>METHODS</b>Glioblastoma U87MG cells, which over-express epidermal growth factor receptor (EGFR), were transfected with antisense-EGFR constructs. Several clones with stable expression of lower or undetectable levels of EGFR protein were obtained. The effect of antisense-EGFR on cell differentiation was studied using morphological evaluation and western blotting analysis of glial fibrillary acidic protein (GFAP) expression. The effect of antisense-EGFR on cell cycle was studied by flow cytometry and immunohistochemical analysis of p53, Rb, p16 and CDK4 expressions. The effect of antisense-EGFR on telomerase activity was studied by telomeric repeat amplification protocol (TRAP) assay.</p><p><b>RESULTS</b>U87MG cells that were transfected with antisense-EGFR constructs had smaller cell bodies and longer processes, and expressed higher level of GFAP compared with that of the control cells. Flow cytometric analysis showed that the proportion of cells in G(0)/G(1) phases of the cell cycle in the antisense EGFR cDNA transfected clones increased significantly when compared with control cells, whereas the proportion of cells in S phase decreased markedly. In addition, immunohistochemical analysis showed that the expression of wild-type p53 was significantly increased in the antisense-EGFR cDNA transfected clones, whereas the expressions of Rb, p16 and CDK4 were not altered. TRAP assay revealed that telomerase activity in the antisense-EGFR clones was significantly decreased.</p><p><b>CONCLUSIONS</b>Antisense-EGFR transfection inhibits U87MG cell growth by inducing cell differentiation and p53 expression, G(1) cell cycle arrest and inhibition of telomerase activity.</p>
Subject(s)
Humans , Cell Line, Tumor , DNA, Antisense , Therapeutic Uses , DNA, Complementary , Therapeutic Uses , Flow Cytometry , Glioblastoma , Chemistry , Drug Therapy , Pathology , Immunohistochemistry , ErbB Receptors , Genetics , Retinoblastoma Protein , Transfection , Tumor Suppressor Protein p53ABSTRACT
<p><b>OBJECTIVE</b>To study the effects of wild-type PTEN on gene expressions of glioblastomas.</p><p><b>METHODS</b>Glioblastoma U87MG cells, which express inactivated PTEN, were transfected with wild-type PTEN constructs and stable transfected clones were selected. Then, cDNA microarray analyses were used to identify differentially expressed genes in wild-type PTEN transfected cells and control cells.</p><p><b>RESULTS</b>Transfected wild-type PTEN inhibited the proliferation of U87MG. By cDNA microarray analyses, 89 cDNA clones were identified, which were differentially expressed in wild-type PTEN transfected cells and control cells. Among these genes, 13 genes were unknown and 76 genes were known genes, including glial fibrillary acidic protein, p21/WAF1, human TGF-beta inducible early protein, human DNA fragmentation factor 45 etc.</p><p><b>CONCLUSION</b>Wild-type PTEN can affect the expressions of multiple genes, by which it regulates the proliferation, differentiation and apoptosis of glioblastomas.</p>