Aurora B inhibition induces polyploidy and mitotic catastrophe in HER2-amplified breast cancer: Telomere shortening as a potential anticancer mechanism of AZD1152-HQPA

Polyploidy, a conserved mechanism involved in normal development and tissue homeostasis, plays a paradoxical role in cancer by facilitating both tumor progression and therapeutic vulnerability. Although polyploidization may confer survival advantages to cancer cells, its controlled induction could represent an effective anticancer strategy. Aurora B kinase, a critical regulator of mitosis, plays a pivotal role in ensuring chromosomal integrity and preventing polyploidy. However, its role in chromosome ploidy and telomere length maintenance in breast cancer remains insufficiently explored. In this study, we identified a significant association between Aurora B overexpression and poor prognosis exclusively in patients with HER2-amplified breast cancer. Treatment with AZD1152-HQPA, a selective Aurora B kinase inhibitor, significantly reduced cell viability and colony-forming potential, with a pronounced effect on HER2-amplified breast cancer cell lines. Importantly, we found that Aurora B inhibition is sufficient to induce polyploidy/multinucleation (8 N and 16 N), cellular enlargement, and mitotic catastrophe. Furthermore, we observed telomere shortening, downregulation of the human telomerase reverse transcriptase (hTERT) and TERRA (telomeric repeat-containing RNA), and a concomitant increase in ROS production following Aurora B inhibition and polyploidization. Mechanistically, we investigated the protein-protein interaction between Aurora B kinase and upstream regulators of hTERT. Collectively, this study elucidates a novel anticancer mechanism associated with Aurora B inhibition, revealing that AZD1152-HQPA not only impairs mitotic fidelity and promotes polyploidization but also compromises the telomere/telomerase maintenance system. These findings highlight the therapeutic potential of Aurora B inhibitors in targeting telomere-associated vulnerabilities in polyploid cancer cells.