Use of Cyclophosphamide as a Positive Control in the Presence of S9 in the ToxTracker® Assay

UKEMS 2022 -- The ToxTracker® Assay is a panel of mouse embryonic stem cells (mES) with pathways tagged via green fluorescent protein (GFP) such that the biological reactivity and potential carcinogenic properties of novel substances can be identified. The panel of biomarkers was established following extensive genome-wide transcription profiling. Six reporters are used, one per cell line. Each reporter cell line was derived from the parent cell line (B4418). Two reporters are associated with DNA damage (Bscl2-GFP and Rtkn-GFP), two reporters are associated with Oxidative Stress (Srxn1-GFP and Blvrb-GFP), one reporter is associated with Protein damage (Ddit3-GFP) and one reporter is associated with a p53-mediated cellular stress response (Btg2-GFP). When tested in the absence and presence of a rat liver metabolic activation system (S9), the combined resultant data from the six reporters (and the parent cell line where appropriate) provides indications of the principle types of biological damage induced by the compound of interest. To increase the spectrum of potential positive controls in the presence of rat liver S9, we have tested a well characterised and commonly used chemical in Genetic Toxicology assays, cyclophosphamide (CPA) in the ToxTracker® Assay.