Induction of leukemia cell apoptosis by cheliensisin A involves down-regulation of Bcl-2 expression.
OBJECTIVE
To investigate the apoptosis-inducing effect of cheliensisin A (GC-51), a novel styryl-lactone isolated from Goniothalamus cheliensis, on human promyelocytic leukemia HL-60 cells and the mechanism of action involved.


METHODS
Apoptotic cell death was determined by morphological examination and DNA agarose gel electrophoresis. The activity of caspase-3 was assessed using Western blotting and the expression of Bcl-2 and Bax genes was analyzed using the reverse transcription-polymerase chain reaction (RT-PCR) method.


RESULTS
GC-51 significantly inhibited the proliferation of HL-60 cells with an IC50 of 2.4+/-0.2 micromol/L and effectively induced apoptosis in HL-60 cells. Exposure of HL-60 cells to 10 micromol/L GC-51 for 8 h resulted in approximately 53% of the cells undergoing apoptosis. Caspase-3 was activated in GC-51-treated cells, which was manifested by the appearance of the 17 kDa active form of caspase-3 and the cleavage of poly(ADP-ribose) polymerase (PARP). Meanwhile, GC-51 markedly reduced the expression of the anti-apoptotic gene Bcl-2 and increased the expression of the pro-apoptotic gene Bax. The apoptosis-inducing effect of GC-51 was cAMP-dependent protein kinase (PKA) dependent because PKA, but not the protein kinase C, specific inhibitor H-89, blocked the induction of apoptosis by GC-51 in HL-60 cells.


CONCLUSIONS
The results demonstrate that GC-51 effectively induces apoptosis in HL-60 cells and that this effect is PKA-dependent and involves the downregulation of Bcl-2 expression and the activation of caspase-3.
Zhong
Li
L
Shanghai Institute of Materia Medica, Shanghai Institutes for Biological Sciences, Shanghai 201203, China.
Li
Chao-ming
CM
Hao
Xiao-jiang
XJ
Lou
Li-guang
LG
D029061:Annonaceae / Q000737:chemistry; D000972:Antineoplastic Agents, Phytogenic / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism; D049109:Cell Proliferation / Q000187:drug effects; D017868:Cyclic AMP-Dependent Protein Kinases / Q000037:antagonists & inhibitors; D004852:Epoxy Compounds / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D015972:Gene Expression Regulation, Neoplastic; D018922:HL-60 Cells; D006801:Humans; D007546:Isoquinolines / Q000494:pharmacology; D010946:Plants, Medicinal / Q000737:chemistry; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000235:genetics / Q000378:metabolism*; D011753:Pyrones / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D013449:Sulfonamides / Q000494:pharmacology; D051028:bcl-2-Associated X Protein
D000972:Antineoplastic Agents, Phytogenic; C494826:BAX protein, human; D004852:Epoxy Compounds; D007546:Isoquinolines; D019253:Proto-Oncogene Proteins c-bcl-2; D011753:Pyrones; D013449:Sulfonamides; D051028:bcl-2-Associated X Protein; C504861:cheliensisin A; D017868:Cyclic AMP-Dependent Protein Kinases; C505407:CASP3 protein, human; D053148:Caspase 3; D020169:Caspases; C063509:N-(2-(4-bromocinnamylamino)ethyl)-5-isoquinolinesulfonamide