Coamplification of DDX1 correlates with an improved survival probability in children with MYCN-amplified human neuroblastoma.
OBJECTIVE
Amplification of the MYCN oncogene at chromosome 2p24-25 identifies an aggressive subtype of human neuroblastoma with a poor clinical outcome. Differences in amplicon structure and coamplification of genes telomeric and centromeric to the MYCN oncogene have previously been described. A relevant role of gene coamplification for neuroblastoma pathogenesis remains elusive.


METHODS
We analyzed 98 primary neuroblastoma tumors with MYCN amplification for coamplification of seven additional genes at chromosome 2p24-25 (DDX1, NAG, NSE1, LPIN1, EST-AA581763, SMC6, and SDC1). Two semiquantitative multiplex polymerase chain reactions were used to obtain the amplification status of the target genes in relation to a reference gene on chromosome 2q (Inhibin-beta-b). Furthermore, mRNA expression pattern of coamplified genes in a subset of tumors was analyzed.


RESULTS
Our results show that the frequency of gene coamplification on 2p24-25 in neuroblastoma is correlated directly to the physical distance to MYCN. Coamplification is correlated to an upregulated gene expression for DDX1 and NAG. Coamplification of the DDX1 gene within 400kb telomeric to MYCN identifies a subgroup of advanced stage neuroblastoma tumors with a more favorable outcome (P =.027, log-rank test). A high expression level of DDX1 is associated with a trend towards a better survival probability (P =.058, log-rank test).


CONCLUSIONS
Our results indicate that DDX1 coamplification correlates with a better prognosis and improved patient survival in MYCN-amplified neurobastoma.
Weber
Axel
A
Children's Hospital, Pedriatric Oncology and Hematology, University of Marburg, Germany.
Imisch
Patricia
P
Bergmann
Eckhard
E
Christiansen
Holger
H
D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D002889:Chromosomes, Human, Pair 2 / Q000235:genetics*; D053487:DEAD-box RNA Helicases; D004273:DNA, Neoplasm; D005260:Female; D005784:Gene Amplification; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D000071447:N-Myc Proto-Oncogene Protein; D009447:Neuroblastoma / Q000235:genetics* / Q000473:pathology*; D009687:Nuclear Proteins / Q000235:genetics*; D015513:Oncogene Proteins / Q000235:genetics*; D016133:Polymerase Chain Reaction; D011379:Prognosis; D020365:RNA Helicases / Q000235:genetics*; D016019:Survival Analysis
D004273:DNA, Neoplasm; C459801:MYCN protein, human; D000071447:N-Myc Proto-Oncogene Protein; D009687:Nuclear Proteins; D015513:Oncogene Proteins; C086252:DDX1 protein, human; D053487:DEAD-box RNA Helicases; D020365:RNA Helicases