targets

Members of the myc oncogene family are often amplified or mutated in human tumours. In the March 15 EMBO Journal, Boon et al. described the use of a neuroblastoma cell line with an inducible N-myc allele to identify genes regulated by N-myc (EMBO Journal 2001, 20:1383-1393). They performed serial analysis of gene expression (SAGE) to detect over a hundred genes up-regulated upon N-myc expression. The target genes included over 50 encoding ribosomal proteins, as well as key genes in rRNA maturation and ribosome assembly. Boon et al. also found a 45% higher rRNA content in cells expressing N-myc. Many of the identified N-myc target genes are also up-regulated in neuroblastomas with N-myc amplifications, and about 40% are also upregulated by the related c-myc transcription factor. Induction of the protein synthesis machinery by myc oncogenes may explain their role in regulating cell size.