Abstract 1564: Novel combination of TRIP13 and Aurora kinase A inhibition demonstrated extensive DNA damage and immunogenic cell death in RB-deficient cancers
Authors: Ghosh Soma , Mazumdar Tuhina , Yapindi Lacin , Sinha Pragya , Sastry Jagannadha , Johnson Faye M. 
Published: April 2023

Many lethal cancer types have inactivation of the retinoblastoma (Rb) tumor suppressor pathway including cancers caused by human papillomavirus (HPV), which causes &gt;5% of all cancers worldwide. There are no therapies that uniquely target Rb-deficient cancers. Biomarker-selected, molecular targeted therapy for Rb-deficient cancers represents both an unmet need and a translational knowledge gap. To address this gap, we recently published data that support a model in which Rb-deficient cancers, having high levels of Mad2, survive owing to TRIP13-mediated inhibition of Mad2 and Aurora A-mediated mitotic progression. The combination of Aurora A inhibition (alisertib) plus TRIP13 depletion caused extensive apoptosis in Rb-deficient, but not in Rb-proficient, cancer cells. Both Aurora A and TRIP13 are involved in the cell’s response to DNA damage and apoptosis that can lead to immunogenic cell death (ICD), prompting us to investigate the mechanism underlying the synthetic lethality of TRIP13 and Aurora A in Rb-deficient cancer cells.

We transfected two HPV+ cell lines with TRIP13 or control siRNA and incubated with 100nM alisertib. We also generated two stable HPV+ cell lines with TRIP13KO. In both these systems, TRIP13 KD or KO alone did not cause apoptosis. Incubation with alisertib resulted in significant cell death, that validated our previous findings. We then tested the effect of the combination on DNA damage. Alisertib caused robust increases in γH2AX, pTIF1β (KAP1, TRIM28), and DNA PKcs, measured using immunoblotting, in both TRIP13 KD and KO HPV+ cell lines. We also observed enhanced γH2AX staining using confocal microscopy.

ICD leads to activation of immune cells by the dying cancer cells in the tumor microenvironment involving the release of antigenic fragments that are engulfed, processed and presented by antigen presenting cells for the induction of antigen-specific T-cell responses. Studies have shown DNA damage stimulates the cGAS/STING pathway leading to ICD. In our system, we saw that TRIP13KO and KD in HPV+ cells treated with alisertib, resulted in marked activation of the cGAS/STING pathway and release of cytochrome C and IL1α in the cell supernatant, which are markers of pyroptosis. Additionally, we also observed gasdermin-E cleavage. The combination further led to increased cancer cell secretion of GM-CSF, IL6, and IL18 that can activate macrophages, NK cells and T-cells.

The selective effect of the combination in Rb-deficient cancer cells allowed us to significantly reduce the concentration of alisertib. By sparing normal cells that express Rb, this combination can potentially reduce treatment toxicity in patients with Rb-deficient cancers. The ICD induced by this combination may lead to host T-cell engagement, thereby further enhancing tumor elimination. This work can shape future clinical trials that can change current treatment regime.

Citation Format: Soma Ghosh, Tuhina Mazumdar, Lacin Yapindi, Pragya Sinha, Jagannadha Sastry, Faye M. Johnson. Novel combination of TRIP13 and Aurora kinase A inhibition demonstrated extensive DNA damage and immunogenic cell death in RB-deficient cancers [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 1564.