Targeting HASPIN in gemcitabine-resistant pancreatic cancer cells by lead optimization of thioadenosine analogue

Despite multiple kinase inhibitors having been developed for cancer therapy, mitotic kinases remain difficult to target with small molecules due to severe adverse effects on proliferating normal cells. Recently, HASPIN, a mitotic kinase responsible for histone H3 phosphorylation, has emerged as a promising cancer-specific target. In this study, we synthesized a novel thioadenosine analogue, LJ5157, based on the structure of the previously developed HASPIN inhibitor LJ4827. In silico transcriptome analysis of pancreatic cancer patient data from The Cancer Genome Atlas identified HASPIN as not only a cancer-specific target but also a potential key player in overcoming gemcitabine resistance. To evaluate the therapeutic potential of LJ5157, we tested its efficacy in pancreatic cancer cells, particularly gemcitabine-resistant Panc-1 (GR) cells. The inhibitor exhibited potent anti-cancer activity, effectively suppressing the growth of GR cells, which showed more dysregulated cell cycle progression and greater proportion of polyploid cells compared to wild-type Panc-1 cells. Furthermore, it demonstrated superior efficacy in reducing the mitotic population of polyploid GR cells, which correlated with significant tumor growth inhibition in a GR-cell-derived xenograft model. Further optimization of LJ4827 led to development of LJ5242, an analogue with enhanced selectivity for HASPIN and improved cell cycle inhibitory potency. These findings highlight HASPIN inhibition as a promising strategy for targeting chemoresistant pancreatic cancer and further identify thioadenosine as a valuable pharmacophore for developing clinically viable HASPIN inhibitors.