Refined mapping of 12q13-q15 amplicons in human malignant gliomas suggests CDK4/SAS and MDM2 as independent amplification targets.
We have reported previously that about 15% of anaplastic astrocytomas and glioblastomas show amplification and overexpression of one or more genes from chromosomal segment 12q13-q15 (G. Reifenberger et al., Cancer Res., 54, 4299-4303, 1994). The genes most frequently amplified and overexpressed were CDK4 (with coamplification of SAS) and MDM2. Because individual malignant gliomas showed CDK4/SAS amplification but no MDM2 amplification and vice versa, the possibility remained of a common amplification target gene located between CDK4 and MDM2. We have addressed this question by performing a detailed amplicon mapping of a series of 24 primary malignant gliomas and two glioblastoma cell lines with 12q13-q15 amplification. All tumors and cell lines were analyzed at eight gene loci and six anonymous loci from 12q13-q15, including seven loci located between CDK4 and MDM2. These studies revealed two centers of amplification, one at CDK4/SAS and the other at MDM2. A number of loci located close to either MDM2 or CDK4/SAS, including the genes GADD153, GLI, RAP1B, A2MR, and IFNG, were found to be coamplified in some tumors but not overexpressed consistently. All amplicons were discontinuous between CDK4/SAS and MDM2. Our results thus exclude a common amplification target between CDK4/SAS and MDM2 and provide additional evidence that these genes represent two independent targets of selection.
Reifenberger
G
G
Department of Neuropathology, Heinrich Heine University, Düsseldorf, Germany.
Ichimura
K
K
Reifenberger
J
J
Elkahloun
A G
AG
Meltzer
P S
PS
Collins
V P
VP
D000328:Adult; D000368:Aged; D001932:Brain Neoplasms / Q000235:genetics*; D002874:Chromosome Mapping / Q000379:methods*; D002881:Chromosomes, Human, Pair 12 / Q000235:genetics*; D051358:Cyclin-Dependent Kinase 4; D018844:Cyclin-Dependent Kinases / Q000235:genetics*; D015342:DNA Probes / Q000235:genetics; D005260:Female; D005784:Gene Amplification / Q000235:genetics*; D005909:Glioblastoma / Q000235:genetics*; D006801:Humans; D008297:Male; D008875:Middle Aged; D008969:Molecular Sequence Data; D009363:Neoplasm Proteins / Q000235:genetics*; D009687:Nuclear Proteins; D011518:Proto-Oncogene Proteins / Q000235:genetics*; D051736:Proto-Oncogene Proteins c-mdm2
D015342:DNA Probes; D009363:Neoplasm Proteins; D009687:Nuclear Proteins; D011518:Proto-Oncogene Proteins; C497206:MDM2 protein, human; D051736:Proto-Oncogene Proteins c-mdm2; C495900:CDK4 protein, human; D051358:Cyclin-Dependent Kinase 4; D018844:Cyclin-Dependent Kinases