Nonrandom karyotypic changes in immortal and tumorigenic Syrian hamster cells induced by diethylstilbestrol

Treatment of Syrian hamster embryo cells with diethylstilbestrol (DES) resulted in the induction of immortal cell lines that progressed and formed tumors in nude mice. Four independently treated cell lines were analyzed cytogenetically at several passages during neoplastic progression. The immortal cell lines at the early passages had no structural abnormalities but did have numerical changes. For example, gain of chromosome 11 was found in all immortal cell lines, and gain of chromosome 19 was found in two of four cell lines. Tumorigenic cells showed not only a variety of numerical abnormalities but also structural abnormalities. Loss of a sex chromosome and gain of chromosome 19 were found in six of seven tumors. Gain of chromosome 11, which was found in all immortal cell lines, disappeared in five of seven tumors. Structural abnormalities involving chromosomes 2 and 3 were found in three of seven tumors. Many marker chromosomes were also found in the tumors. These results support our hypothesis that DES-induced nondisjunction is important in its ability to induce cell transformation and suggests that gain of chromosome 11 and/or 19 may play a role in DES-induced neoplastic progression. Furthermore, these results indicate that for the acquisition of tumorigenicity, additional numerical or structural changes are needed, suggesting that multiple genetic events are required in the multistep process of carcinogenesis.