title: BCL2 Inhibitors as Anticancer Drugs: A Plethora of Misleading BH3 Mimetics.
abstract: Antiapoptotic BCL2 proteins play a major role in tumor cell survival. Hence, BCL2 inhibitors have been developed as direct inducers of apoptosis. ABT-199 (venetoclax) received breakthrough therapy designation from the FDA due to its apparent efficacy in CLL and AML. However, resistance to ABT-199 is mediated by other BCL2 proteins including BCLXL and MCL1. Considerable effort has been expended seeking novel "BH3 mimetics" that inhibit all of these BCL2 proteins. While many BH3 mimetics inhibit BCL2 proteins in vitro, they fail to directly inhibit them in intact cells. Many BH3 mimetics induce the unfolded protein response culminating in induction of the proapoptotic protein NOXA, which in turn inhibits MCL1. We propose simple experiments to validate BH3 mimetics in cells. A true BCL2 inhibitor will rapidly induce apoptosis in chronic lymphocytic leukemia cells ex vivo A BCLXL inhibitor will rapidly induce apoptosis in platelets. Finally, a BH3 mimetic targeting MCL1 will inhibit its degradation thereby inducing rapid MCL1 accumulation. Compounds that fail these tests should no longer be called BH3 mimetics. We now have a toolbox of selective inhibitors for most of the BCL2 proteins, and we hope these new tools will lead to effective treatment options for many cancers. Mol Cancer Ther; 15(9); 2011-7. ©2016 AACR.
authors.affiliation: Norris Cotton Cancer Center, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire.
authors.forename: Ryan
authors.initials: R
authors.lastname: S Soderquist
authors.affiliation: Norris Cotton Cancer Center, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire. Alan.R.Eastman@Dartmouth.edu.
authors.forename: Alan
authors.initials: A
authors.lastname: Eastman
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology* / Q000627:therapeutic use*; D000067558:Biological Mimicry; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D006801:Humans; D064549:Myeloid Cell Leukemia Sequence 1 Protein / Q000037:antagonists & inhibitors; D009369:Neoplasms / Q000188:drug therapy* / Q000235:genetics / Q000378:metabolism*; D010446:Peptide Fragments / Q000494:pharmacology / Q000627:therapeutic use; D011518:Proto-Oncogene Proteins / Q000494:pharmacology / Q000627:therapeutic use; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects; D056811:Unfolded Protein Response
chemical_list: D000970:Antineoplastic Agents; C474007:Bax protein (53-86); D064549:Myeloid Cell Leukemia Sequence 1 Protein; C498702:PMAIP1 protein, human; D010446:Peptide Fragments; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2