Selection and amplification of heterologous genes encoding adenosine deaminase in mammalian cells.

We demonstrate that an adenosine deaminase (ADA) cDNA gene can function as a dominant selectable and amplifiable marker for gene transfer experiments in mammalian cells. Cells that incorporate the gene can be selected by growth in the presence of low concentrations of the ADA inhibitor 2'-deoxycoformycin with cytotoxic concentrations of adenosine or its analogue 9-beta-D-xylofuranosyl adenine. The DNA copy number of the transfected ADA minigene in the isolated transformants of Chinese hamster ovary cells can be amplified greater than 100-fold by growth in ADA selection media and increasing concentrations of 2'-deoxycoformycin. This selection scheme may allow for the introduction and subsequent amplification of heterologous DNA in a variety of mammalian cells.