Abstract 2398: Disruption of mitochondrial metabolism by ClpP activation in triple negative breast cancer

Abstract ONC201 is a novel anticancer compound currently in over 20 clinical trials for multiple different cancers, including triple negative breast cancer (TNBC). We recently demonstrated that ONC201 and the more potent TR compounds selectively activate the mitochondrial protease ClpP. While previous studies demonstrated substantial effects on mitochondrial metabolism, the consequences of ClpP activation on cancer cell metabolism are yet to be defined. To investigate this, we performed an unbiased metabolomics and proteomics analysis comparing the effects of ONC201 and TR-57 on the TNBC metabolome and proteome. Consistent with these compounds targeting the mitochondria, our studies identified multiple mitochondrial metabolites and enzymes that were impacted by ClpP activation, such as TCA cycle intermediates and enzymes, heat shock proteins and mitochondrial ribosomal proteins. In addition to previously reported elements of the integrated stress response (ATF4, CHOP), we identified several proteins that were upregulated as part of the mitochondrial-nuclear signaling process. qRT-PCR was used to determine the impact of ONC201 or TR-57 treatment on transcript levels of proteomic hits. Importantly, the effects of ONC201 and the TR compounds on these proteins and cell growth were abolished in ClpP null cells. In summary, our studies further demonstrate that loss of metabolic function in mitochondria contributes to the anticancer activity of these ClpP activator compounds. Citation Format: Emily M. Fennell, Lucas J. Aponte-Collazo, Blake R. Rushing, Yuan-Yuan Li, Wimal Pathmasiri, Joshua D. Wynn, Paul R. Graves, Ekhson L. Holmuhamedov, Laura E. Herring, Edwin J. Iwanowicz, Lee M. Graves. Disruption of mitochondrial metabolism by ClpP activation in triple negative breast cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 2398.