Scopoletin induces apoptosis in human promyeloleukemic cells, accompanied by activations of nuclear factor kappaB and caspase-3.
Scopoletin (6-methoxy-7-hydroxycoumarin) is a phenolic coumarin and a member of the phytoalexins. In this study we investigated whether scopoletin caused apoptosis in HL-60 promyelocytic cells and, if so, by what mechanisms. We found that scopoletin induced apoptosis as confirmed by a characteristic ladder pattern of discontinuous DNA fragments in a dose-dependent manner. The signal cascade activated by scopoletin included the heterodimeric redox-sensitive transcription factor NF-kappaB, which exhibited an upregulation of nuclear factor-kappa B (NF-kappaB) translocation to the nucleus by increase of IkappaBalpha degradation. In addition, scopoletin activated caspase-3 as was evidenced by both the proteolytic cleavage of the proenzyme and increased protease activity. Activation of caspase-3 resulted in the cleavage of 116 kDa poly(ADP-ribose) polymerase (PARP) to 85 kDa cleavage product in time-and dose-dependent fashions. Prior treatment of the cells with pyrrolidine dithiocarbamate, a potent inhibitor of NF-kappaB activation, or Ac-DEVD-CHO, a specific caspase-3 inhibitor, prevented scopoletin-induced caspase-3 activation, PARP cleavage, and finally DNA fragmentation. Taken together, these results suggest that scopoletin induces NF-kappaB activation, which, in turn, causes activation of caspase-3, degradation of PARP, and eventually leads to apoptotic cell death in HL-60 cells.
Kim
Eun-Kyung
EK
Department of Physiology, School of Oriental Medicine, Wonkwang University, Iksan, Chonbuk 570-749, South Korea.
Kwon
Kang-Beom
KB
Shin
Byung-Cheul
BC
Seo
Eun-A
EA
Lee
Young-Rae
YR
Kim
Jong-Suk
JS
Park
Jin-Woo
JW
Park
Byung-Hyun
BH
Ryu
Do-Gon
DG
D000704:Analysis of Variance; D017209:Apoptosis / Q000187:drug effects*; D015153:Blotting, Western; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism; D053938:DNA Fragmentation / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D004587:Electrophoresis, Agar Gel; D024202:Electrophoretic Mobility Shift Assay; D004789:Enzyme Activation / Q000187:drug effects; D042381:Granulocyte Precursor Cells / Q000187:drug effects*; D018922:HL-60 Cells; D006801:Humans; D020672:I-kappa B Proteins / Q000378:metabolism; D000072000:NF-KappaB Inhibitor alpha; D016328:NF-kappa B / Q000378:metabolism; D011065:Poly(ADP-ribose) Polymerases / Q000378:metabolism; D021381:Protein Transport / Q000187:drug effects; D012603:Scopoletin / Q000633:toxicity*; D015398:Signal Transduction / Q000187:drug effects*; D013778:Tetrazolium Salts; D013844:Thiazoles
D020672:I-kappa B Proteins; D016328:NF-kappa B; C000606204:NFKBIA protein, human; D013778:Tetrazolium Salts; D013844:Thiazoles; D000072000:NF-KappaB Inhibitor alpha; D011065:Poly(ADP-ribose) Polymerases; C505407:CASP3 protein, human; D053148:Caspase 3; D020169:Caspases; C022616:thiazolyl blue; D012603:Scopoletin