Activated Expression of the N- myc Gene in Human Neuroblastomas and Related Tumors

In neuroblastoma lines in which the N- myc gene is present as a single copy, the expression of N- myc as messenger RNA is increased relative to that in nonneuroblastoma cell lines and tumors. The increase of expression in neuroblastomas with amplified N- myc genes is the result of (i) an increase in the absolute amount of expression of each N- myc gene and (ii) an increase in the copy number of the N- myc gene. A second gene—which is amplified in many of the same lines as N- myc —is expressed to about the same degree in most human cell lines and primary tumors regardless of origin (when normalized to gene copy number). Thus, a change in the regulation of N- myc expression in neuroblastomas and certain other tumors results in greatly increased expression of each N- myc gene copy.