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Mol. Cells 2007; 24(1): 95-104

Published online January 1, 1970

© The Korean Society for Molecular and Cellular Biology

Acacetin-induced Apoptosis of Human Breast Cancer MCF-7 Cells Involves Caspase Cascade, Mitochondria-mediated Death Signaling and SAPK/JNK1/2-c-Jun Activation

Hye-Young Shim, Jong-Hwa Park, Hyun-Dong Paik, Seung-Yeol Nah, Darrick S.H.L. Kim and Ye Sun Han

Abstract

The mechanism of acacetin-induced apoptosis of human breast cancer MCF-7 cells was investigated. Acacetin caused 50% growth inhibition (IC50) of MCF-7 cells at 26.4 ? 0.7 ?M over 24 h in the MTT assay. Apoptosis was characterized by DNA fragmentation and an increase of sub-G1 cells and involved activation of caspase-7 and PARP (poly-ADP-ribose polymerase). Maximum caspase 7 activity was observed with 100 ?M acacetin for 24 h. Caspase 8 and 9 activation cascades mediated the activation of caspase 7. Acacetin caused a reduction of Bcl-2 expression leading to an increase of the Bax:Bcl-2 ratio. It also caused a loss of mitochondrial membrane potential that induced release of cytochrome c and apoptosis inducing factor (AIF) into the cytoplasm, enhancing ROS generation and subsequently resulting in apoptosis. Pretreatment of cells with N-acetylcysteine (NAC) reduced ROS generation and cell growth inhibition, and pretreatment with NAC or a caspase 8 inhibitor (Z-IETD-FMK) inhibited the acacetin-induced loss of mitochondrial membrane potential and release of cytochrome c and AIF. Stress-activated protein kinase/c-Jun NH4-terminal kinase 1/2 (SAPK/ JNK1/2) and c-Jun were activated by acacetin but extracellular-regulated kinase 1/2 (Erk1/2) nor p38 mitogen-activated protein kinase (MAPK) were not. Our results show that acacetin-induced apoptosis of MCF-7 cells is mediated by caspase activation cascades, ROS generation, mitochondria-mediated cell death signaling and the SAPK/JNK1/2-c-Jun signaling pathway, activated by acacetin-induced ROS generation.

Keywords Acacetin; Apoptosis Inducing Factor; Bax; Bcl-2; c-Jun; c-Jun NH4-Terminal Kinase; Caspase; Cytochrome c; Mitochondrial Membrane Potential; Reactive Oxygen Species.

Article

Research Article

Mol. Cells 2007; 24(1): 95-104

Published online August 31, 2007

Copyright © The Korean Society for Molecular and Cellular Biology.

Acacetin-induced Apoptosis of Human Breast Cancer MCF-7 Cells Involves Caspase Cascade, Mitochondria-mediated Death Signaling and SAPK/JNK1/2-c-Jun Activation

Hye-Young Shim, Jong-Hwa Park, Hyun-Dong Paik, Seung-Yeol Nah, Darrick S.H.L. Kim and Ye Sun Han

Abstract

The mechanism of acacetin-induced apoptosis of human breast cancer MCF-7 cells was investigated. Acacetin caused 50% growth inhibition (IC50) of MCF-7 cells at 26.4 ? 0.7 ?M over 24 h in the MTT assay. Apoptosis was characterized by DNA fragmentation and an increase of sub-G1 cells and involved activation of caspase-7 and PARP (poly-ADP-ribose polymerase). Maximum caspase 7 activity was observed with 100 ?M acacetin for 24 h. Caspase 8 and 9 activation cascades mediated the activation of caspase 7. Acacetin caused a reduction of Bcl-2 expression leading to an increase of the Bax:Bcl-2 ratio. It also caused a loss of mitochondrial membrane potential that induced release of cytochrome c and apoptosis inducing factor (AIF) into the cytoplasm, enhancing ROS generation and subsequently resulting in apoptosis. Pretreatment of cells with N-acetylcysteine (NAC) reduced ROS generation and cell growth inhibition, and pretreatment with NAC or a caspase 8 inhibitor (Z-IETD-FMK) inhibited the acacetin-induced loss of mitochondrial membrane potential and release of cytochrome c and AIF. Stress-activated protein kinase/c-Jun NH4-terminal kinase 1/2 (SAPK/ JNK1/2) and c-Jun were activated by acacetin but extracellular-regulated kinase 1/2 (Erk1/2) nor p38 mitogen-activated protein kinase (MAPK) were not. Our results show that acacetin-induced apoptosis of MCF-7 cells is mediated by caspase activation cascades, ROS generation, mitochondria-mediated cell death signaling and the SAPK/JNK1/2-c-Jun signaling pathway, activated by acacetin-induced ROS generation.

Keywords: Acacetin, Apoptosis Inducing Factor, Bax, Bcl-2, c-Jun, c-Jun NH4-Terminal Kinase, Caspase, Cytochrome c, Mitochondrial Membrane Potential, Reactive Oxygen Species.

Mol. Cells
Nov 30, 2023 Vol.46 No.11, pp. 655~725
COVER PICTURE
Kim et al. (pp. 710-724) demonstrated that a pathogen-derived Ralstonia pseudosolanacearum type III effector RipL delays flowering time and enhances susceptibility to bacterial infection in Arabidopsis thaliana. Shown is the RipL-expressing Arabidopsis plant, which displays general dampening of the transcriptional program during pathogen infection, grown in long-day conditions.

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