In Silico Discovery of 5′-Modified 7‑Deoxy-7-ethynyl-4′-thioadenosine as a HASPIN Inhibitor and Its Synergistic Anticancer Effect with the PLK1 Inhibitor

Despite genetic perturbations resulting in embryo lethality
for
most mitotic kinases, loss of the histone H3 mitotic kinase HASPIN
reveals no adverse effect in mice models, establishing HASPIN as a
promising target for anticancer therapy. However, developing a HASPIN
inhibitor from conventional pharmacophores poses a technical challenge
as this atypical kinase shares slight similarities with eukaryotic
protein kinases. Chemically modifying a cytotoxic 4′-thioadenosine
analogue through high genotoxicity yielded several novel nongenotoxic
kinase inhibitors. In silico apporoaches utilizing transcriptomic
and chemical similarities with known compounds and KINOMEscan profiles
unveiled the HASPIN inhibitor LJ4827. LJ4827’s specificity
and potency as a HASPIN inhibitor were verified through in vitro kinase
assay and X-ray crystallography. HASPIN inhibition by LJ4827 reduced
histone H3 phosphorylation and impeded Aurora B recruitment in cancer
cell centromeres but not in noncancer cells. Through transcriptome
analysis of lung cancer patients, PLK1 was determined as a druggable
synergistic partner to complement HASPIN inhibition. Chemical or genetic
PLK1 perturbation with LJ4827 effectuated pronounced lung cancer cytotoxicity
in vitro and in vivo. Therefore, LJ4827 is a novel anticancer therapeutic
for selectively impeding cancer mitosis through potent HASPIN inhibition,
and simultaneous HASPIN and PLK1 interference is a promising therapeutic
strategy for lung cancer.