title: Apigenin-induced-apoptosis is mediated by the activation of PKCdelta and caspases in leukemia cells.
abstract: Apigenin, a flavone abundantly found in fruits and vegetables, exhibits antiproliferative, anti-inflammatory, and antimetastatic activities through poorly defined mechanisms. In the present study, the treatment of different cell lines with apigenin resulted in selective antiproliferative and apoptotic effect in monocytic and lymphocytic leukemias. Apigenin-induced-apoptosis was mediated by the activation of caspase-9 and caspase-3. Apigenin was found intracellularly and localized to the mitochondria. Treatment of monocytic cells with apigenin was accompanied by an increase in reactive oxygen species (ROS) and phosphorylation of the MAPKs, p38 and ERK. However, the inhibition of ROS, p38 or ERK failed to block apoptosis, suggesting that these cellular responses induced by apigenin are not essential for the induction of apoptosis. In addition, apigenin induced the activation of PKCdelta. Pharmacological inhibition of PKCdelta, the expression of dominant-negative PKCdelta and silencing of PKCdelta in leukemia cells showed that apigenin-induced-apoptosis requires PKCdelta activity. Together, these results indicate that this flavonoid provides selective activity to promote caspase-dependent-apoptosis of leukemia cells and uncover an essential role of PKCdelta during the induction of apoptosis by apigenin.
authors.affiliation: Pulmonary and Critical Care, USA.
authors.forename: Melissa A
authors.initials: MA
authors.lastname: Vargo
authors.forename: Oliver H
authors.initials: OH
authors.lastname: Voss
authors.forename: Frantisek
authors.initials: F
authors.lastname: Poustka
authors.forename: Arturo J
authors.initials: AJ
authors.lastname: Cardounel
authors.forename: Erich
authors.initials: E
authors.lastname: Grotewold
authors.forename: Andrea I
authors.initials: AI
authors.lastname: Doseff
mesh_terms: D016475:3T3 Cells; D000818:Animals; D047310:Apigenin / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects* / Q000502:physiology; D053148:Caspase 3; D053453:Caspase 9; D020169:Caspases / Q000378:metabolism / Q000502:physiology*; D004789:Enzyme Activation / Q000187:drug effects; D018922:HL-60 Cells; D006801:Humans; D019169:Jurkat Cells; D020014:K562 Cells; D007938:Leukemia / Q000473:pathology; D051379:Mice; D008928:Mitochondria / Q000378:metabolism; D051745:Protein Kinase C-delta / Q000378:metabolism*; D017382:Reactive Oxygen Species / Q000378:metabolism; D014407:Tumor Cells, Cultured; D020298:U937 Cells; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism*
chemical_list: D017382:Reactive Oxygen Species; D047310:Apigenin; D051745:Protein Kinase C-delta; D048051:p38 Mitogen-Activated Protein Kinases; C505407:CASP3 protein, human; C506433:CASP9 protein, human; C505409:Casp3 protein, mouse; C506434:Casp9 protein, mouse; D053148:Caspase 3; D053453:Caspase 9; D020169:Caspases