Abstract LB-080: Discovery of an unconventional form of cell-death in colorectal cancer

Abstract

Abstract We recently discovered unique, structurally constrained 4-pyridinyl - containing compounds that induce a form of caspase-independent cell death in colorectal cancer (CRC) cells. This was characterized by the simultaneous induction of dysregulated macropinocytosis and macroautophagy, a type of cell death we have termed ‘methuophagy' (this neologism arises from the Greek ‘methuo', to drink to intoxication and ‘phagy', self-eating). Our new class of small molecular probes (BAPT analogues) do not induce cell death via activation of the well characterized classical apoptotic pathways. In contrast, our BAPT compounds cause methuophagy by inducing the formation and accumulation of fluid-filled, heterogeneous vacuoles and autophagosomes, resulting in metabolic failure, loss of membrane integrity, and detachment of cells from the substratum. Methuophagy produces extensive autophagy without cell shrinkage, chromatin condensation, alteration of mitochondrial membrane potential or nuclear membrane damage. The optimization of the BAPT structure led to the discovery of BAPT-27, which has nanomolar potency in inducing methuophagy in broad spectrum of CRC cell lines and may serve as a prototype for a new class of drugs. BAPT-27 produces methuophagy and surmounts MDR in CRC cells independent of Ras, p53 or other apoptotic protein (i.e. Bax, Bak) or expression of ATP-binding cassette (ABC) transporters. Furthermore, BAPT-27 is non-toxic in normal cells and zebrafish. Based on our findings, we postulate that the induction of methuophagy by BAPT-27 produces endolysosomal trafficking defects that prevent recycling of lysosomes and cause lysosome-to-nucleus signaling defect, a mechanism that disturb cellular clearance and energy metabolism. The selected compounds will allow us to understand the biology of methuophagy-induced cell death and will be particularly beneficial for treatment of patients with apoptotic-resistant and aggressive CRCs. Citation Format: Amit K. Tiwari, Haneen Amawi, Karthikeyan Chandrabose, Paul Erhardt, Piyush Trivedi. Discovery of an unconventional form of cell-death in colorectal cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr LB-080.