Abstract PR007: The combination of TRIP13 and Aurora kinase A inhibition caused cell cycle specific DNA damage and death in Rb-deficient cancers
Authors: Yapindi Lacin , Ghosh Soma , Mazumdar Tuhina , Johnson Faye M. 
Published: January 2024

Abstract
Many diverse, common, and lethal cancer types have inactivation of the retinoblastoma (RB1, Rb) tumor suppressor pathway including cancers caused by the human papillomavirus (HPV), which causes &gt;5% of all cancers worldwide. Despite therapeutic advances, advanced Rb-deficient cancers are still lethal with therapy-related adverse effects. Moreover, there are no therapies that uniquely target HPV-driven or Rb-deficient cancers. Therefore, biomarker-selected, targeted therapy for Rb-deficient cancers represents both a substantial unmet need and a significant translational knowledge gap. Rb-deficient cancer cells depend on Aurora A kinases to bypass the spindle assembly checkpoint (SAC) and survive due to overexpression of the mitotic checkpoint protein Mad2. Thyroid hormone receptor interactor 13 (TRIP13) catalyzes the ATP-dependent conversion of Mad2 from its active to inactive form, which turns off the SAC. Our lab discovered that the combination of Aurora A inhibition with alisertib plus TRIP13 depletion induced extensive apoptosis selectively in Rb-deficient cancer cells. Moreover, our results demonstrated that the synthetic lethality between Aurora A and TRIP13 reflects mitotic catastrophe. The combination led to highly abnormal mitoses in Rb-deficient cancer cells, evidenced by unaligned, dispersed chromosomes, mitotic spindle defects, and G2/M arrest. Moreover, live cell imaging showed that alisertib treatment increased the duration of first mitoses and induced mitotic cell death, which was even more pronounced in second mitotic events. The combination resulted in both prolonged mitotic arrest and enhanced lethality, indicated by increased mitotic cell death after the first mitoses and interphase cell death following the first mitotic arrest. Furthermore, using degron tagging to rapidly degrade TRIP13, we showed that TRIP13 depletion led to transient mitotic arrest in cells that were in late G2, supporting the role of TRIP13 in regulating the SAC and mitotic progression. Since prolonged mitotic arrest is known to cause DNA damage and both Aurora A and TRIP13 are known to be involved in the DNA damage response, we also tested the effect of the combination treatment on DNA damage. Treating Rb-deficient cancer cells with the combination resulted in robust increases in gamma-H2AX, pTIF1 beta (KAP1, TRIM28), and DNA PKcs. The lethal effects of the combination required mitotic entry as concurrent CDK1 inhibition with RO-3306 prevented apoptosis and DNA damage induced by the combination. The selective effect of the combination in Rb-deficient cancer cells may have a wide therapeutic index resulting in less toxic and more effective therapy. Additionally, targeting mitosis may contribute to a cancer-specific effect due to cancer cells’ high proliferation rate. Our study suggests that targeting TRIP13 and Aurora A led to DNA damage and death specifically during mitosis in Rb-deficient cells. This work has potential to establish a foundation for future clinical trials and may change current clinical practice paradigms.
Citation Format: Lacin Yapindi, Soma Ghosh, Tuhina Mazumdar, Faye M. Johnson. The combination of TRIP13 and Aurora kinase A inhibition caused cell cycle specific DNA damage and death in Rb-deficient cancers [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: DNA Damage Repair: From Basic Science to Future Clinical Application; 2024 Jan 9-11; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2024;84(1 Suppl):Abstract nr PR007.