An assessment of the utility of the yeast GreenScreen assay in pharmaceutical screening

In this paper we describe an initial reproducibility study of 12 proprietary compounds followed by the assessment of 51 marketed pharmaceuticals and, lastly, a summary of the data so far from 2698 proprietary compounds from the Johnson & Johnson (J&J) compound library, in the yeast GreenScreen assay (GSA). In this assay, a reporter system in the yeast cells employs the DNA damage inducible promoter of the RAD54 gene, fused to the extremely stable green fluorescent protein (GFP). The assay proved to be very robust, the Excel templates provided by Gentronix with the assay interfaced well with in-house J&J systems with little adaptation, the assay was very rapid to perform and used very little compound. The results confirm previous work which suggests that the yeast GSA detects different classes of genotoxic compounds to the Ames assay and as a result can help screen out important genotoxic compounds at the pre-regulatory test phase that are missed by Ames-test-based screens alone. A combination of SAR evaluation of genotoxicity plus an Ames-test-based screen and the GSA provides a powerful pre-regulatory test battery to aid in the selection of successful drug candidates.