Detection of N-myc oncogene expression in human neuroblastoma by in situ hybridization and blot analysis: relationship to clinical outcome.

We studied N-myc oncogene expression in 13 human neuroectodermal tumors and one teratoma by in situ hybridization. In four of six neuroblastomas, there was increased N-myc expression (15 to 49% of the cells). Many of the primitive neuroblastic cells had an increase of N-myc RNA not observed in the larger, more differentiated cells. Two neuroblastomas matured to ganglioneuromas; no biopsies performed during this progression expressed increased N-myc RNA. Three ganglioneuroblastomas, two tumors presenting as ganglioneuromas, a cerebral neuroectodermal tumor, a neurofibrosarcoma, and the teratoma did not have increased N-myc expression. The data obtained by in situ hybridization correlated well with data obtained by blot analysis. Neuroblastomas/ganglioneuroblastomas with a favorable course did not have appreciable elevation of N-myc expression over 10 to 77 mo of follow-up; thus N-myc may not be involved in the maintenance of the neoplastic state. However, such tumors with a fatal outcome 2 to 14 mo after diagnosis usually had elevated N-myc expression. These findings suggest a relationship between elevated levels of N-myc RNA and poor prognosis.