4.3. Cell Viability Assays and Calculation of LC50 Doses for PARP Inhibitors

Cells were seeded into 96-well plates (UWB1.289 2000 cells/well; UWB1.289+BRCA1 1000 cells/well; PEO1 1500 cells/well; PEO4 4000 cells/well; OVCAR-3 3000 cells/well; A2780 and A2780veliR 5000 cells/well) and treated with niraparib, olaparib, rucaparib, talazoparib (cat. #HY-10619, cat. #HY-10619, cat. #HY-10617, cat. #HY-16106, respectively; MedChemExpress, Monmouth Junction, NJ, USA) or veliparib (ABT-888; cat. #ALX-270-444-M005, Sapphire Biosciences, Waterloo, NSW, Australia) for 5 days before being assessed for cell viability using the CellTiter 96 Aqueous One Solution Cell Proliferation Assay (cat. #G3581, Promega, Madison, USA). This assay measures cellular metabolic activity and is a surrogate for cell viability. All results using this assay are described in the context of cell viability. Each experiment was performed in triplicate and repeated four times, with data reported as the mean ± SEM.

Relative lethal concentration 50 (LC50), the concentration required to bring the dose curve halfway between the top and bottom plateau of the curve, was calculated using GraphPad Prism 9. To address the issue that some of the drugs tested did not achieve total loss of cell viability at high levels, data were normalised to vehicle alone (100%) and the highest drug concentration where a plateau was observed (0%). A non-linear regression curve was fitted to the data and LC50 concentrations extrapolated [57].