title: GSK-3beta reactivation with LY294002 sensitizes hepatoma cells to chemotherapy-induced apoptosis.
abstract: Constitutive activation of phosphatidylinositol 3-kinase (PI3K) confers resistance to apoptotic stimuli induced by chemotherapeutic agents in a variety of cancer cells. Therefore, the comprehension of mechanisms whereby PI3K downregulation interferes with chemotherapy is of major clinical interest for the elaboration of combined anticancer treatment modalities. Here, we examined the molecular mechanisms whereby the PI3K inhibitor LY294002 sensitized p53- and Fas-deficient hepatoma cells to etoposide and camptothecin. LY294002 increased Hep3B cell susceptibility to chemotherapy-induced apoptosis by enhancing the expression of DR4 and DR5 and the activation of caspase-8 and -3. Moreover, LY294002-mediated sensitization to chemotherapy involved mitochondrial Bax translocation and cytosolic cytochrome c accumulation. In Hep3B cells, LY294002 led to the reactivation of glycogen synthase kinase-3beta (GSK-3beta) by promoting its dephosphorylation on the serine 9 residue independently from Akt inhibition. The transient transfection of a constitutively active and non-phosphorylable S9AGSK-3beta mutant sensitized cells to etoposide cytotoxic effects while cell treatment with the small GSK-3beta inhibitor SB-415286 repressed the sensitizing effect of LY294002 on chemotherapy-induced apoptosis and caspase-8 activation. Altogether, our results show that LY294002 sensitizes hepatoma cells to chemotherapy-induced apoptosis via death receptor and mitochondria signalling pathways and that GSK-3beta reactivation is involved in this process. Therefore, PI3K-mediated GSK-3beta inhibition could be a mechanism by which cancer cells escape from chemotherapy-induced apoptosis.
authors.affiliation: INSERM U.402, Faculté de Médecine Saint-Antoine, Paris, France. beurel@st-antoine.inserm.fr
authors.forename: Eléonore
authors.initials: E
authors.lastname: Beurel
authors.forename: Michel
authors.initials: M
authors.lastname: Kornprobst
authors.forename: Marie-José
authors.initials: MJ
authors.lastname: Blivet-Van Eggelpoël
authors.forename: Axelle
authors.initials: A
authors.lastname: Cadoret
authors.forename: Jacqueline
authors.initials: J
authors.lastname: Capeau
authors.forename: Christele
authors.initials: C
authors.lastname: Desbois-Mouthon
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis; D015153:Blotting, Western; D002166:Camptothecin / Q000494:pharmacology; D006528:Carcinoma, Hepatocellular / Q000473:pathology*; D053148:Caspase 3; D053181:Caspase 8; D020169:Caspases / Q000378:metabolism; D045744:Cell Line, Tumor; D002867:Chromones / Q000494:pharmacology; D045304:Cytochromes c / Q000378:metabolism; D053938:DNA Fragmentation; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005047:Etoposide / Q000494:pharmacology; D005434:Flow Cytometry; D038362:Glycogen Synthase Kinase 3 / Q000378:metabolism*; D000071679:Glycogen Synthase Kinase 3 beta; D006801:Humans; D009025:Morpholines / Q000494:pharmacology; D009154:Mutation; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D010766:Phosphorylation; D053220:Receptors, TNF-Related Apoptosis-Inducing Ligand; D018124:Receptors, Tumor Necrosis Factor / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012694:Serine / Q000737:chemistry; D014162:Transfection; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism; D019014:fas Receptor / Q000378:metabolism
chemical_list: D000970:Antineoplastic Agents; D002867:Chromones; D004791:Enzyme Inhibitors; D009025:Morpholines; D053220:Receptors, TNF-Related Apoptosis-Inducing Ligand; D018124:Receptors, Tumor Necrosis Factor; C105190:TNFRSF10A protein, human; C505639:TNFRSF10B protein, human; D016159:Tumor Suppressor Protein p53; D019014:fas Receptor; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one; D012694:Serine; D005047:Etoposide; D045304:Cytochromes c; D019869:Phosphatidylinositol 3-Kinases; C000605506:GSK3B protein, human; D000071679:Glycogen Synthase Kinase 3 beta; D038362:Glycogen Synthase Kinase 3; C505407:CASP3 protein, human; C505530:CASP8 protein, human; D053148:Caspase 3; D053181:Caspase 8; D020169:Caspases; D002166:Camptothecin