title: Human Pluripotent Stem Cells and Derived Neuroprogenitors Display Differential Degrees of Susceptibility to BH3 Mimetics ABT-263, WEHI-539 and ABT-199.
abstract: Human embryonic stem cells (hESCs) are hypersensitive to genotoxic stress and display lower survival ability relative to their differentiated progeny. Herein, we attempted to investigate the source of this difference by comparing the DNA damage responses triggered by the topoisomerase I inhibitor camptothecin, in hESCs, human induced pluripotent stem cells (hiPSCs) and hESCs-derived neuroprogenitors (NP). We observed that upon camptothecin exposure pluripotent stem cells underwent apoptosis more swiftly and at a higher rate than differentiated cells. However, the cellular response encompassing ataxia-telangiectasia mutated kinase activation and p53 phosphorylation both on serine 15 as well as on serine 46 resulted very similar among the aforementioned cell types. Importantly, we observed that hESCs and hiPSCs express lower levels of the anti-apoptotic protein Bcl-2 than NP. To assess whether Bcl-2 abundance could account for this differential response we treated cells with ABT-263, WEHI-539 and ABT-199, small molecules that preferentially target the BH3-binding pocket of Bcl-xL and/or Bcl-2 and reduce their ability to sequester pro-apoptotic factors. We found that in the absence of stress stimuli, NP exhibited a higher sensitivity to ABT- 263 and WEHI-539 than hESCs and hiPSCs. Conversely, all tested cell types appeared to be highly resistant to the Bcl-2 specific inhibitor, ABT-199. However, in all cases we determined that ABT-263 or WEHI-539 treatment exacerbated camptothecin-induced apoptosis. Importantly, similar responses were observed after siRNA-mediated down-regulation of Bcl-xL or Bcl-2. Taken together, our results suggest that Bcl-xL contrary to Bcl-2 contributes to ensure cell survival and also functions as a primary suppressor of DNA double-strand brake induced apoptosis both in pluripotent and derived NP cells. The emerging knowledge of the relative dependence of pluripotent and progenitor cells on Bcl-2 and Bcl-xL activities may help to predict cellular responses and potentially manipulate these cells for therapeutic purposes in the near future.
authors.affiliation: Laboratorios de Investigación Aplicada a Neurociencias, LIAN-CONICET, Fundación FLENI, Ruta 9, Km 53, (B1625XAF) Escobar, Buenos Aires, Argentina.
authors.forename: Carolina Paola
authors.initials: CP
authors.lastname: García
authors.affiliation: Laboratorios de Investigación Aplicada a Neurociencias, LIAN-CONICET, Fundación FLENI, Ruta 9, Km 53, (B1625XAF) Escobar, Buenos Aires, Argentina.
authors.forename: Guillermo Agustín
authors.initials: GA
authors.lastname: Videla Richardson
authors.affiliation: Laboratorios de Investigación Aplicada a Neurociencias, LIAN-CONICET, Fundación FLENI, Ruta 9, Km 53, (B1625XAF) Escobar, Buenos Aires, Argentina.
authors.forename: Nicolás Alexis
authors.initials: NA
authors.lastname: Dimopoulos
authors.affiliation: Laboratorios de Investigación Aplicada a Neurociencias, LIAN-CONICET, Fundación FLENI, Ruta 9, Km 53, (B1625XAF) Escobar, Buenos Aires, Argentina.
authors.forename: Damián Darío
authors.initials: DD
authors.lastname: Fernandez Espinosa
authors.affiliation: Laboratorios de Investigación Aplicada a Neurociencias, LIAN-CONICET, Fundación FLENI, Ruta 9, Km 53, (B1625XAF) Escobar, Buenos Aires, Argentina.
authors.forename: Santiago Gabriel
authors.initials: SG
authors.lastname: Miriuka
authors.affiliation: Laboratorios de Investigación Aplicada a Neurociencias, LIAN-CONICET, Fundación FLENI, Ruta 9, Km 53, (B1625XAF) Escobar, Buenos Aires, Argentina.
authors.forename: Gustavo Emilio
authors.initials: GE
authors.lastname: Sevlever
authors.affiliation: Laboratorios de Investigación Aplicada a Neurociencias, LIAN-CONICET, Fundación FLENI, Ruta 9, Km 53, (B1625XAF) Escobar, Buenos Aires, Argentina.
authors.forename: Leonardo
authors.initials: L
authors.lastname: Romorini
authors.affiliation: Laboratorios de Investigación Aplicada a Neurociencias, LIAN-CONICET, Fundación FLENI, Ruta 9, Km 53, (B1625XAF) Escobar, Buenos Aires, Argentina.
authors.forename: María Elida
authors.initials: ME
authors.lastname: Scassa
mesh_terms: D000814:Aniline Compounds / Q000494:pharmacology*; D064007:Ataxia Telangiectasia Mutated Proteins / Q000378:metabolism; D019086:Bridged Bicyclo Compounds, Heterocyclic / Q000494:pharmacology*; D002166:Camptothecin / Q000494:pharmacology; D002460:Cell Line; D000066449:Human Embryonic Stem Cells / Q000166:cytology / Q000378:metabolism*; D006801:Humans; D057026:Induced Pluripotent Stem Cells / Q000166:cytology / Q000378:metabolism*; D058953:Neural Stem Cells / Q000166:cytology / Q000378:metabolism*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D013449:Sulfonamides / Q000494:pharmacology*; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism; D051020:bcl-X Protein / Q000378:metabolism
chemical_list: D000814:Aniline Compounds; C000595707:BCL2 protein, human; C494811:BCL2L1 protein, human; D019086:Bridged Bicyclo Compounds, Heterocyclic; D019253:Proto-Oncogene Proteins c-bcl-2; D013449:Sulfonamides; C495901:TP53 protein, human; D016159:Tumor Suppressor Protein p53; D051020:bcl-X Protein; C576324:ATM protein, human; D064007:Ataxia Telangiectasia Mutated Proteins; C579720:venetoclax; C528561:navitoclax; D002166:Camptothecin