[Activation of ras and myc proto-oncogenes in human breast carcinoma and neuroblastoma].

DNA from human breast carcinoma (SK-BR-3) and neuroblastoma (LA-N-1) cell lines are capable of inducing foci of transformed NIH 3T3 cells after DNA-mediated gene transfer. The blot hybridization analysis of DNA from primary and secondary NIH 3T3 transformants identified additional sequences homologous to the c-Ha-ras 1 oncogene, and revealed amplification of nucleotide sequences homologous to the v-myc oncogene. Restriction fragments of the amplified myc-related sequences correspond to c-myc (SK-BR-3) and N-myc (LA-N-1) loci of the human genome. The results show that active Ha-ras oncogenes can coexist with altered myc oncogenes in breast carcinomas and neuroblastomas. This suggests that a multi-step mechanism involves both ras and myc genes and their cooperation in the development of these tumors.