Abstract LB167: Acetalax (Oxyphenisatin acetate, NSC 59687) and bisacodyl (dulcolax) cause oncosis in triple negative breast cancer by poisoning the ion exchange membrane protein TRPM4

Abstract

Abstract Triple negative breast cancer (TNBC) is generally unresponsive to current therapies, and the development of new anticancer agents is needed. Oxyphenisatin acetate, called Acetalax, which was used as a laxative in the 1950’s, has recently been reported to have anticancer activity in several murine cancer models. In this study we demonstrate that Acetalax and its structural analog laxative analog bisacodyl (Dulcolax) exhibit potent antiproliferative activity in TNBC cell lines. We show that both cause oncosis, a non-apoptotic cell death characterized by cellular and nuclear swelling and cell membrane blebbing that leads to mitochondrial dysfunction and ATP depletion. Acetalax was further shown to enhance immune and inflammatory responses and inhibit protein synthesis. Mechanistically, we provide evidence that TRPM4 (Transient Receptor Potential Melastatin member 4) is poisoned by Acetalax and bisacodyl. By blocking TRPM4, a monovalent cation channel, Acetalax and Bisacodyl cause oncosis, and TNBC cells without endogenous TRPM4 expression as well as TRPM 4 knockout TNBC cells were found to be Acetalax- and Bisacodyl resistant. TRPM4 was also lost in cells with acquired Acetalax resistance. Moreover TRPM4 is rapidly degraded the ubiquitin-proteasome system upon acute exposure to Acetalax and bisacodyl. Together, these results demonstrate that TRPM4 is a previously unknown target of Acetalax and Bisacodyl and that TRPM4 expression in cancer cells is a predictor of Acetalax and Bisacodyl efficacy, and could be used for the clinical development of these drugs as anticancer agents. Citation Format: Makito Mizunuma, Christophe Redon, Liton Saha, Naoko Takebe, Yves G. Pommier. Acetalax (Oxyphenisatin acetate, NSC 59687) and bisacodyl (dulcolax) cause oncosis in triple negative breast cancer by poisoning the ion exchange membrane protein TRPM4 [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(7_Suppl):Abstract nr LB167.