High-Throughput Screening Tool to Identify Small Molecule Inhibitors of Telomerase.

Telomerase reverse transcriptase is a ribonucleoprotein complex that maintains telomere length in rapidly dividing cells, thus enabling cellular immortality. Despite being recognized as an important cancer target for decades, no small molecule telomerase inhibitors have been approved as anticancer therapeutics to date. Several limitations, including the absence of high-throughput screening tools, have posed challenges to the telomerase drug discovery field. Here, we describe a high-throughput, fluorescently coupled screening method employing a chemically modified reporter nucleotide. We utilize the telomerase as a surrogate model as it shares a high degree of active site homology with the human enzyme. We piloted this tool by screening a chemical library of ∼3600 nucleoside mimetics to demonstrate excellent assay quality, and identified 2 compounds with inhibitory activity that were further validated in a direct enzymatic assay. Our work introduces a method that has the potential to uncover novel telomerase inhibitors for further drug discovery efforts.