myc Gene Amplification and Expression in Primary Human Neuroblastoma1

Although N-myc amplification in neuroblastomas correlates with poor prognosis, not all neuroblastomas which fail to respond to therapy have N-myc amplification. To determine whether other modes of myc gene activation underlie progression of some neuroblastomas, 45 were analyzed for amplification of N-wiyc, c-myc and L-myc and 26 were studied for transcription of these oncogenes. N-myc amplification was found in 6 of 45 tumors; no tumor had amplification of c-myc or L-myc. Transcription of both N-myr and c-myc occurred in 21 of 26 neuroblastomas. No tumor without \-myc amplification had a level of \-myc expression near that of a tumor or cell line with amplification. One tumor with \-myc amplification was the only specimen with N-myc but not c-myc expres sion. Five samples had c-myc but not \-myc expression; all had histological features of ganglioneuroma. DNA index did not correlate with myc gene amplification or expression. It is concluded that N-ni.vcand c-myc are commonly expressed in primary untreated neuroblastomas, but in the absence of N-myc amplification, expression of these genes does not appear to correlate with disease progression.