Amplification, expression and localization of the c-myc gene in BSp73 rat tumor cell lines.

Metastatic (ASML 14-1, ASmv) and non metastatic (AS17-4) cell lines of the rat BSp73 pancreatic adenocarcinoma were investigated for amplification and expression of oncogene DNA. The c-myc gene was amplified, but only in one metastatic variant, ASML. The degree of amplification (3.5-fold) increased after prolongued in vitro cultivation (17.5-fold). All three tumor cell lines expressed c-myc and ras mRNA. Ras expression was at the same level as in rat liver. C-myc expression was considerably above the level in rat liver, but also differed considerably between the metastatic variants. In the metastatic ASML cells the c-myc gene was localized by in situ hybridization on a marker chromosome derived from chromosome 7. The karyotypes of the metastatic variants are different and have no common marker chromosomes. Our results obtained with the BSp73 tumor model do not support a role of the c-myc gene in the metastatic process.