Amplified DNA sequences in cancers.

Amplification of genes other than known oncogenes was analyzed using an in-gel DNA renaturation method, in which a mixture of restriction fragments of radioactively labelled tracer DNA and unlabelled driver DNA was electrophoresed and amplified DNA fragments were visualized after two cycles of denaturation and renaturation in the gel. Different DNA fragments were found to be amplified more than 400 fold in NB1, a neuroblastoma cell line, in Y79, a retinoblastoma cell line and in H69, a small cell lung carcinoma cell line, in addition to 120 to 160-fold amplification of N-myc gene in these three cell lines.