Abstract 1638: Regulation of spindle pole integrity by the MASTL-ENSA-aurora a pathway during mitosis

Abstract The preservation of spindle pole integrity is crucial for proper spindle assembly and chromosome segregation in mitosis, yet the precise mechanisms governing spindle pole integrity remain elusive. During mitosis, phosphorylated Ensa (p-ENSA) localizes to spindle poles, and the inhibition of ENSA leads to a range of mitotic defects, including misaligned chromosomes, multipolar spindles, asymmetric bipolar spindles, and centrosome aberrations, resulting in a delayed mitotic progression. Remarkably, the mitotic delay induced by ENSA inhibition is alleviated upon depletion of PP2A-B55α, but spindle pole defects persist. Significantly, we have observed an interaction between ENSA and Aurora A during mitosis, and the inhibition of ENSA diminishes Aurora A expression at the mitotic spindle poles. Intriguingly, the injection of MKI-2-sensitized tumors is associated with heightened chromosomal instability and downregulation of the MASTL-ENSA-Aurora A pathway in an orthotopic breast cancer mouse model. These findings offer new insights into the regulation of spindle pole integrity through the MASTL-ENSA-Aurora A pathway during mitosis, emphasizing the pivotal role of ENSA in recruiting Aurora A to the spindle pole, independently of PP2A-B55α. Citation Format: Seul Kim, Kyoungho Jun, Ye-Hyun Kim, Jae Sung Kim. Regulation of spindle pole integrity by the MASTL-ENSA-aurora a pathway during mitosis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 1638.