Chromosome findings in human neuroblastomas xenografted in nude mice

Chromosomes were successfully studied in 8 of 9 human neuroblastomas (NBs) xenografted in nude mice. Structural abnormalities in the short arm of chromosome #1 were found in 6 of the 8 tumors; these included nonreciprocal translocations and simple deletions. The breakpoints were distributed between 1p11 and 1p34, and all of them had lost the terminal portion of 1p (1pter----1p34). Double minutes (DMs) and homogeneously staining regions (HSRs) were observed in 7 tumors; 6 had either DMs or HSRs, and one had some cells with DMs and other cells with HSR. Only one tumor had neither DMs, nor HSRs. Our study revealed that structural abnormalities in the NB xenografts were essentially the same as those in the NB cell lines and fresh tumors reported previously, and that DMs and HSRs were seen in most NB xenografts as frequently as in NB cell lines.