ABSTRACT
PURPOSE: PTEN and DMBT1, candidate tumor suppressor genes on chromosome 10q, were identified based on deletions in glioblastoma and medulloblastoma cell lines. We examined the occurrences and frequencies of allelic deletions on chromosome 10q23 and 10q25 by loss of heterozygosity (LOH) analysis in 24 pediatric brain tumors to investigate the possible involvement of PTEN and DMBT1 gene deletions in the development of pediatric brain tumors. METHOD: LOH was analyzed by polymerase chain reaction (PCR) of PTEN locus on 10q23 using 2 microsatellite markers, D10S608 and D10S579, and of DMBT1 locus on 10q25-q26.1 using a microsatellite marker, D10S587, in 24 pediatric brain tumor (18 medulloblastomas, 3 ependymomas, 2 glioblastomas and 1 supratentorial primitive neuroectodermal tumor) DNAs extracted from archival tissue specimens (case 1-15, 19) or fresh frozen tissue specimens (case 16-18, 20-24). RESULTS: Allelic deletions were detected in 4 of 23 informative cases (17%) on D10S608, 6 of 24 informative cases (25%) on D10S579, and 8 of 24 informative cases (33%) on D10S587. Overall 11 of 24 cases (46%) showed LOH on chromosome 10q at PTEN or DMBT1 loci, and they were 10 medulloblastomas and 1 ependymoma pathologically. Of 18 medulloblastomas, 7 (39%) exhibited LOH at PTEN locus, 8 (44%) exhibited LOH at DMBT1 locus, and 10 (56%) exhibited LOH at one or both of loci. CONCLUSION: Our results support the notion that PTEN and DMBT1 tumor suppressor gene deletions may be involved in the pathogenesis of pediatric brain tumors. Our results also suggested that PTEN and DMBT1 tumor suppressor gene deletions may not be important in molecular mechanism of glioblastoma development in children as in adults.
Subject(s)
Adult , Child , Humans , Brain Neoplasms , Brain , Cell Line , DNA , Ependymoma , Gene Deletion , Genes, Tumor Suppressor , Glioblastoma , Loss of Heterozygosity , Medulloblastoma , Microsatellite Repeats , Neural Plate , Polymerase Chain ReactionABSTRACT
Objective To detect the PTEN gene mutation and loss of heterozygosity(LOH) on chromosome 10q in oligodendrogliomas. Methods The entire PTEN coding sequence of the 9 exons were screened by 9 different PCR reactions and followed by denaturing gradient gel electrophoresis(DGGE) and direct sequencing for detecte mutation.Microsatellite markers with fluorochrome on 10?q amplified by PCR were used to detecte LOH by PAGE on an automatic sequencer and analyzed with the Gene Scan program in 55 oligodendrogliomas and mixed oligodendrogliomas. Results The PTEN gene somatic mutations were detected in 2 tumors,one case that carried a PTEN mutation deletion T base in position 20 resulting stop codon moved to 347.Another case was a A to C transition at the codon 139 resulting in changeing from Leu to Phe.Twenty\|three of 55(42%) cases were observed the loss of heterozygosity(LOH) on chromosome 10?q.Fifteen of 55 cases allelic loss were detected on loci D10S 541 which located in the PTEN gene region at 10?q 23^3 .Twelve of 55 cases were detected totaled LOH on 10?q.Conclusion\ The PTEN gene mutation is rare,loss of allelic 10?q is frequente in oligodendrogliomas,especially in high\|grade oligodendrogliomas.It could indicate that LOH on 10?q has an enhance effect in tumor progression,and chromosome 10?q harbors additional tumor suppressor genes in oligodendrogliomas.\;[