Gene amplification in PNETs/medulloblastomas: mapping of a novel amplified gene within the MYCN amplicon.
OBJECTIVE
The pathological entity of primitive neuroectodermal tumour/medulloblastoma (PNET/MB) comprises a very heterogeneous group of neoplasms on a clinical as well as on a molecular level. We evaluated the importance of DNA amplification in medulloblastomas and other primitive neuroectodermal tumours (PNETs) of the CNS.


METHODS
Restriction landmark genomic scanning (RLGS), a method that allows the detection of low level amplification, was used. RLGS provides direct access to DNA sequences circumventing positional cloning efforts. Furthermore, we analysed several samples by CGH.


METHODS
Twenty primary medulloblastomas, five supratentorial PNETs, and five medulloblastoma cell lines were studied.


RESULTS
Although our analysis confirms that gene amplification is generally a rare event in childhood PNET/MB, we found a total of 17 DNA fragments that were amplified in seven different tumours. Cloning and sequencing of several of these fragments confirmed the previous finding of MYC amplification in the cell line D341 Med and identified novel DNA sequences amplified in PNET/MB. We describe for the first time amplification of the novel gene, NAG, in a subset of PNET/MB. Despite genomic amplification, NAG was not overexpressed in the tumours studied. We have determined that NAG maps less than 50 kb 5' of DDX1 and approximately 400 kb telomeric of MYCN on chromosome 2p24.


CONCLUSIONS
We found a similar but slightly higher frequency of amplification than previously reported. We present several DNA fragments that may belong to the CpG islands of novel genes amplified in a small subset of PNET/MB. As an example we describe for the first time the amplification of NAG in the MYCN amplicon in PNET/MB.
Frühwald
M C
MC
Division of Pediatric Hematology and Oncology, The Ohio State University and the Comprehensive Cancer Center, Columbus 43210, USA. fruhwald@uni-muenster.de
O'Dorisio
M S
MS
Rush
L J
LJ
Reiter
J L
JL
Smiraglia
D J
DJ
Wenger
G
G
Costello
J F
JF
White
P S
PS
Krahe
R
R
Brodeur
G M
GM
Plass
C
C
D015152:Blotting, Northern; D015139:Blotting, Southern; D001932:Brain Neoplasms / Q000235:genetics* / Q000473:pathology; D002528:Cerebellar Neoplasms / Q000235:genetics / Q000473:pathology; D002648:Child; D002675:Child, Preschool; D018244:Chromosomes, Artificial, Yeast; D020451:Contig Mapping; D018899:CpG Islands; D004252:DNA Mutational Analysis; D004273:DNA, Neoplasm / Q000032:analysis*; D020224:Expressed Sequence Tags; D005260:Female; D005784:Gene Amplification; D016259:Genes, myc / Q000235:genetics*; D006801:Humans; D008297:Male; D008527:Medulloblastoma / Q000235:genetics / Q000473:pathology; D009363:Neoplasm Proteins / Q000235:genetics*; D018242:Neuroectodermal Tumors, Primitive / Q000235:genetics*; D009928:Organ Specificity; D016133:Polymerase Chain Reaction; D011110:Polymorphism, Genetic; D014407:Tumor Cells, Cultured
D004273:DNA, Neoplasm; C117339:NBAS protein, human; D009363:Neoplasm Proteins