title: Anti-apoptotic Bcl-2 fails to form efficient complexes with pro-apoptotic Bak to protect from Celecoxib-induced apoptosis.
abstract: The non-steroidal anti-inflammatory drug Celecoxib is a specific inhibitor of cyclooxygenase-2. Apart from its inhibitor function, Celecoxib induces apoptosis through the intrinsic pathway which is controlled by the Bcl-2 family members. In Jurkat T lymphoma cells, treatment with Celecoxib results in a rapid decline of the anti-apoptotic Bcl-2-related protein Mcl-1. The depletion of Mcl-1 is sufficient for apoptosis induction and can be blocked by overexpression of Bcl-xL but not by the close homologue Bcl-2. The present investigation analyzed the mechanism by which Bcl-xL prevents apoptosis induction whereas Bcl-2 failed to. Our data show that the involvement of the orphan nuclear receptor Nur77/TR3 specifically targeting Bcl-2 but not Bcl-xL was not involved in Celecoxib-induced apoptosis. Surprisingly, BH3-only proteins Bid, Bim, and Puma of the Bcl-2 family were not needed either. However, unlike Bcl-2, Mcl-1, and Bcl-xL sequestered Bak preventing it from activation through a direct interaction. Thus, when abundantly expressed, Bcl-xL can substitute for the loss of Mcl-1 whereas Bcl-2, incapable of forming a high affinity complex with Bak, could not.
authors.affiliation: Department of Radiation Oncology, University Hospital of Tübingen, Hoppe-Seyler-Str. 3, 72076 Tübingen, Germany. justine.rudner@med.uni-tuebingen.de
authors.forename: Justine
authors.initials: J
authors.lastname: Rudner
authors.forename: Simon J
authors.initials: SJ
authors.lastname: Elsaesser
authors.forename: Verena
authors.initials: V
authors.lastname: Jendrossek
authors.forename: Stephan M
authors.initials: SM
authors.lastname: Huber
mesh_terms: D017209:Apoptosis / Q000187:drug effects*; D000068579:Celecoxib; D052246:Cyclooxygenase 2 Inhibitors / Q000494:pharmacology*; D005786:Gene Expression Regulation; D006801:Humans; D019169:Jurkat Cells; D064549:Myeloid Cell Leukemia Sequence 1 Protein; D057105:Nuclear Receptor Subfamily 4, Group A, Member 1 / Q000235:genetics / Q000378:metabolism; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000235:genetics / Q000378:metabolism*; D011720:Pyrazoles / Q000494:pharmacology*; D013449:Sulfonamides / Q000494:pharmacology*; D050998:bcl-2 Homologous Antagonist-Killer Protein / Q000235:genetics / Q000378:metabolism*; D051020:bcl-X Protein / Q000235:genetics / Q000378:metabolism
chemical_list: C494811:BCL2L1 protein, human; D052246:Cyclooxygenase 2 Inhibitors; D064549:Myeloid Cell Leukemia Sequence 1 Protein; C539821:NR4A1 protein, human; D057105:Nuclear Receptor Subfamily 4, Group A, Member 1; D019253:Proto-Oncogene Proteins c-bcl-2; D011720:Pyrazoles; D013449:Sulfonamides; D050998:bcl-2 Homologous Antagonist-Killer Protein; D051020:bcl-X Protein; D000068579:Celecoxib