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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
May 31, 2023 Vol.46 No.5, pp. 259~328
COVER PICTURE
The alpha-helices in the lamin filaments are depicted as coils, with different subdomains distinguished by various colors. Coil 1a is represented by magenta, coil 1b by yellow, L2 by green, coil 2a by white, coil 2b by brown, stutter by cyan, coil 2c by dark blue, and the lamin Ig-like domain by grey. In the background, cells are displayed, with the cytosol depicted in green and the nucleus in blue (Ahn et al., pp. 309-318).

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