Development of a high-throughput screening-amenable assay for human poly(ADP-ribose) polymerase inhibitors

Abstract

Introduction: Poly(ADP-ribose) polymerase (PARP) plays a pivotal role in the repair of DNA strand breaks. However, excessive activation of PARP causes a rapid depletion of intracellular energy, leading to cell death. Inhibitors of PARP have been shown to reduce infarct size in animal models of myocardial ischemia. PARP inhibitors may have potential therapeutic benefit in the treatment of myocardial ischemia, stroke, head trauma, and neurodegenerative disease, and as an adjunct therapy with chemotherapeutic agents/radiation in cancer therapy. Methods: Assays reported in the literature and commercially available PARP assay kits are labor-intensive, use radioactive reagents, use antibodies, and are not readily amenable to Hadamard transform spectroscopy (HTS). Here we report the development and the validation of a nonradioactive PARP assay suitable for HTS. This is a biotinylated NAD-based colorimetric assay in a 96-well plate format. Results: The assay is sensitive, reproducible, and easy to use. The IC 50 values generated for the known PARP inhibitors are in agreement with those generated using the commercial radioactive kit and those reported in the literature. Discussion: The present study demonstrates a sensitive and reproducible methodology capable of screening human PARP inhibitors in high-throughput format.