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 Tribolium castaneum 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.