1. BCL-2 dependence and ABT-737 sensitivity in acute lymphoblastic leukemia
Victoria Del Gaizo Moore, Krysta D Schlis, Stephen E Sallan, Scott A Armstrong, Anthony Letai Blood. 2008 Feb 15;111(4):2300-9. doi: 10.1182/blood-2007-06-098012. Epub 2007 Dec 4.
Cancer cells acquire disruptions in normal signal transduction pathways and homeostatic mechanisms that would trigger apoptosis in normal cells. These abnormalities include genomic instability, oncogene activation, and growth factor independent proliferation. Therefore, cancer cells likely require a block in apoptosis in order to survive. Overexpression of the antiapoptotic protein BCL-2 provides a block in apoptosis that is frequently observed in cancer cells. We have developed methods for the detection and analysis of BCL-2 dependence and here apply them to acute lymphoblastic leukemia (ALL). BH3 profiling, a mitochondrial assay that classifies blocks in the intrinsic apoptotic pathway, indicated a dependence on BCL-2 of both ALL cell lines and primary samples. This dependence predicted that BCL-2 would be complexed with select pro-death BH3 family proteins, a prediction confirmed by the isolation of BCL-2 complexes with BIM. Furthermore, the BH3 profiling and protein analysis predicted that ALL cell lines and primary cells would be sensitive to ABT-737 as a single agent. Finally, BH3 profiling and protein studies accurately predicted a relative degree of sensitivity to BCL-2 antagonism in cell lines. The ALL cells studied exhibit BCL-2 dependence, supporting clinical trials of BCL-2 antagonists in ALL as single agents or combination therapies.
2. The pro-apoptotic domain of BIM protein forms toxic amyloid fibrils
Ravit Malishev, Shani Ben-Zichri, Ofek Oren, Nitzan Shauloff, Tal Peretz, Ran Taube, Niv Papo, Raz Jelinek Cell Mol Life Sci. 2021 Mar;78(5):2145-2155. doi: 10.1007/s00018-020-03623-7. Epub 2020 Aug 25.
BIM is a key apoptotic protein, participating in diverse cellular processes. Interestingly, recent studies have hypothesized that BIM is associated with the extensive neuronal cell death encountered in protein misfolding diseases, such as Alzheimer's disease. Here, we report that the core pro-apoptotic domain of BIM, the BIM-BH3 motif, forms ubiquitous amyloid fibrils. The BIM-BH3 fibrils exhibit cytotoxicity, disrupt mitochondrial functions, and modulate the structures and dynamics of mitochondrial membrane mimics. Interestingly, a slightly longer peptide in which BIM-BH3 was flanked by four additional residues, widely employed as a model of the pro-apoptotic core domain of BIM, did not form fibrils, nor exhibited cell disruptive properties. The experimental data suggest a new mechanistic role for the BIM-BH3 domain, and demonstrate, for the first time, that an apoptotic peptide forms toxic amyloid fibrils.
