Collaborative SAR Modeling and Prospective In Vitro Validation of Oxidative Stress Activation in Human HepG2 Cells

Oxidative stress is the consequence of an abnormal increase
of
reactive oxygen species (ROS). ROS are generated mainly during the
metabolism in both normal and pathological conditions as well as from
exposure to xenobiotics. Xenobiotics can, on the one hand, disrupt
molecular machinery involved in redox processes and, on the other
hand, reduce the effectiveness of the antioxidant activity. Such dysregulation
may lead to oxidative damage when combined with oxidative stress overpassing
the cell capacity to detoxify ROS. In this work, a green fluorescent
protein (GFP)-tagged nuclear factor erythroid 2-related factor 2 (NRF2)-regulated
sulfiredoxin reporter (Srxn1-GFP) was used to measure the antioxidant
response of HepG2 cells to a large series of drug and drug-like compounds
(2230 compounds). These compounds were then classified as positive
or negative depending on cellular response and distributed among different
modeling groups to establish structure–activity relationship
(SAR) models. A selection of models was used to prospectively predict
oxidative stress induced by a new set of compounds subsequently experimentally
tested to validate the model predictions. Altogether, this exercise
exemplifies the different challenges of developing SAR models of a
phenotypic cellular readout, model combination, chemical space selection,
and results interpretation.