Chromosome localization in normal human cells and neuroblastomas of a gene related to c-myc

Cellular oncogenes comprise a class of genes whose aberrant expression or function may be involved in the development of tumours¹. Indeed, several naturally occurring animal and human tumours are associated with consistent alterations in the structure or genomic position of particular cellular oncogenes^2-4. Recently, we isolated a DNA segment having limited similarity to c-myc (termed N-myc) from a human neuroblastoma cell line⁵. Although N-myc was present as a single copy in normal cells, it was selectively amplified up to 140-fold in tumour cells from human neuroblastomas⁵. Now, we have used somatic cell hybrids to show that N-myc is normally localized on the distal short arm of chromosome 2, and in situ hybridization to localize N-myc to chromosome 2p23-24. Further, in situ hybridization localizes amplified N-myc in neuroblastoma cells to homogeneously staining regions (HSRs) on different chromosomes. Thus, our results suggest that amplification and translocation of N-myc may be interrelated processes associated with human neuroblastoma, and demonstrate that lhe site of N-myc amplification is quite variable and bears no apparent relationship to either the normal single-copy locus or recognized sites of non-random chromosome alteration in human neuroblastoma.