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Lookup NU author(s): Dr Rebecca Kenyon,
Professor Archibald Malcolm,
Professor Andrew Pearson,
Professor John Lunec
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Although N-myc amplification is strongly associated with a poor prognosis, not all patients with neuroblastomas having N-myc amplification fare badly. To investigate whether genes other than N-myc are responsible for contributing to the prognosis, we examined seven cell lines and 87 primary tumours for co-amplification of candidate genes known to be present near the normal N-myc locus: ornithine decarboxylase (ODC), ribonucleotide reductase (RRM2), syndecan-1 and a DEAD box protein gene, DDX1. Sequence analysis of the pG21 cDNA clone previously reported to represent an expressed gene frequently co-amplified with N-myc, showed this to be from the DDX1 gene. No co-amplification with the first three genes was found in any of the cell lines or tumour samples. DDX1, however was found to be amplified along with N-myc in 4/6 (67%) cell lines and 6/16 (38%) of the N-myc amplified tumours. Co-amplification of DDX1 and N-myc was found more frequently in stage 4 or 4S tumours than lower stage (1-3) tumours. With the exclusion of a single 4S case, there was a highly significant reduction in the mean disease-free interval from 24.4 ± 4.7 (SE, n = 10) months for cases with co-amplification of N-myc and DDX1 compared with 9.2 ± 1.8 (SE, n = 5) months for those cases showing amplification of N-myc alone (P = 0.0056, Welch's unpaired t-test). No amplification of DDX1, ODC, RRM2, or syndecan-1 was found in the absence of N-myc amplification. These observations indicate that the N-myc amplicon is of varied size and/or position relative to the N-myc gene, with DDX1 representing at least one other gene frequently co-amplified with N-myc. Further studies are required to confirm the biological and prognostic significance of DDX1 co-amplification and to elucidate the role that DDX1 plays in tumour genesis and progression.
Author(s): George, R., Kenyon, R., McGuckin, A, Malcolm, A, Pearson, A.D.J., Lunec, J.
Publication type: Article
Publication status: Published
Print publication date: 01/01/1996
ISSN (print): 0950-9232
ISSN (electronic): 1476-5594
PubMed id: 8622876