title: Anti-apoptotic BCL-2 proteins govern cellular outcome following B-RAF(V600E) inhibition and can be targeted to reduce resistance.
abstract: In theory, pharmacological inhibition of oncogenic signaling is an effective strategy to halt cellular proliferation, induce apoptosis and eliminate cancer cells. In practice, drugs (for example, PLX-4032) that inhibit oncogenes like B-RAFV600E provide relatively short-term success in patients, owing to a combination of incomplete cellular responses and the development of resistance. To define the relationship between PLX-4032-induced responses and resistance, we interrogated the contributions of anti-apoptotic BCL-2 proteins in determining the fate of B-RAFV600E-inhibited melanoma cells. Although PLX-4032 eliminated B-RAFV600E signaling leading to marked cell cycle arrest, only a fraction of cells eventually underwent apoptosis. These data proposed two hypotheses regarding B-RAFV600E inhibition: (1) only a few cells generate a pro-apoptotic signal, or (2) all the cells generate a pro-apoptotic signal but the majority silences this pathway to ensure survival. Indeed, the latter hypothesis is supported by our observations as the addition of ABT-737, an inhibitor to anti-apoptotic BCL-2 proteins, revealed massive apoptosis following PLX-4032 exposure. B-RAFV600E inhibition alone sensitized cells to the mitochondrial pathway of apoptosis characterized by the rapid accumulation of BIM on the outer mitochondrial membrane, which could be functionally revealed by ABT-737 to promote apoptosis and loss of clonogenic survival. Furthermore, PLX-4032-resistant cells demonstrated collateral resistance to conventional chemotherapy, yet could be re-sensitized to PLX-4032 by BCL-2 family inhibition in vivo and conventional chemotherapies in vitro. Our data suggest that inhibiting anti-apoptotic BCL-2 proteins will enhance primary responses to PLX-4032, along with reducing the development of resistance to both targeted and conventional therapies.
authors.affiliation: 1] Department of Oncological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, USA [2] Department of Dermatology, New York, NY, USA [3] The Tisch Cancer Institute, New York, NY, USA.
authors.forename: M N
authors.initials: MN
authors.lastname: Serasinghe
authors.affiliation: 1] Department of Oncological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, USA [2] Department of Dermatology, New York, NY, USA [3] The Tisch Cancer Institute, New York, NY, USA [4] The Graduate School of Biomedical Sciences, New York, NY, USA.
authors.forename: D J
authors.initials: DJ
authors.lastname: Missert
authors.affiliation: 1] Department of Oncological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, USA [2] Department of Dermatology, New York, NY, USA [3] The Tisch Cancer Institute, New York, NY, USA.
authors.forename: J J
authors.initials: JJ
authors.lastname: Asciolla
authors.affiliation: 1] Department of Oncological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, USA [2] The Tisch Cancer Institute, New York, NY, USA.
authors.forename: S
authors.initials: S
authors.lastname: Podgrabinska
authors.affiliation: 1] Department of Oncological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, USA [2] Department of Dermatology, New York, NY, USA [3] The Tisch Cancer Institute, New York, NY, USA.
authors.forename: S Y
authors.initials: SY
authors.lastname: Wieder
authors.affiliation: 1] The Graduate School of Biomedical Sciences, New York, NY, USA [2] Department of Genetics and Genomic Sciences, New York, NY, USA.
authors.forename: S
authors.initials: S
authors.lastname: Izadmehr
authors.affiliation: 1] Department of Oncological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, USA [2] The Graduate School of Biomedical Sciences, New York, NY, USA.
authors.forename: G
authors.initials: G
authors.lastname: Belbin
authors.affiliation: 1] Department of Oncological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, USA [2] The Tisch Cancer Institute, New York, NY, USA [3] The Graduate School of Biomedical Sciences, New York, NY, USA.
authors.forename: M
authors.initials: M
authors.lastname: Skobe
authors.affiliation: 1] Department of Oncological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, USA [2] Department of Dermatology, New York, NY, USA [3] The Tisch Cancer Institute, New York, NY, USA [4] The Graduate School of Biomedical Sciences, New York, NY, USA [5] The Diabetes, Obesity, and Metabolism Institute, New York, NY, USA.
authors.forename: J E
authors.initials: JE
authors.lastname: Chipuk
mesh_terms: D019943:Amino Acid Substitution; D017209:Apoptosis / Q000187:drug effects / Q000235:genetics; D001713:Biphenyl Compounds / Q000494:pharmacology*; D045744:Cell Line, Tumor; D019008:Drug Resistance, Neoplasm / Q000187:drug effects* / Q000235:genetics; D006801:Humans; D007211:Indoles / Q000494:pharmacology*; D008545:Melanoma / Q000188:drug therapy* / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D020125:Mutation, Missense; D009596:Nitrophenols / Q000494:pharmacology*; D010879:Piperazines / Q000494:pharmacology; D048493:Proto-Oncogene Proteins B-raf / Q000235:genetics / Q000378:metabolism*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000235:genetics / Q000378:metabolism*; D013449:Sulfonamides / Q000494:pharmacology*; D000077484:Vemurafenib
chemical_list: C501332:ABT-737; C000595707:BCL2 protein, human; D001713:Biphenyl Compounds; D007211:Indoles; D009596:Nitrophenols; D010879:Piperazines; D019253:Proto-Oncogene Proteins c-bcl-2; D013449:Sulfonamides; D000077484:Vemurafenib; C482119:BRAF protein, human; D048493:Proto-Oncogene Proteins B-raf