Induction of caspase-dependent, p53-mediated apoptosis by apigenin in human neuroblastoma.
Neuroblastoma is a pediatric tumor accounting for 15% of childhood cancer deaths and has a poor prognosis in children >1 year of age. We investigated the ability of apigenin, a nonmutagenic dietary flavonoid that has been shown to have antitumor effects in various tumor cell lines, to inhibit growth and induce apoptosis of the human neuroblastoma cell lines NUB-7, LAN-5, and SK-N-BE(2). Apigenin inhibited colony-forming ability and survival, and induced apoptosis of NUB-7 and LAN-5 cells. The presence of the C2-C3 double bond and the 4'-OH group on the flavonoid structure correlated with the growth-inhibitory potential of apigenin. Furthermore, apigenin inhibited NUB-7 xenograft tumor growth in anonobese diabetic/severe combined immunodeficiency mouse model, likely by inducing apoptosis. Apigenin did not inhibit survival of primary sympathetic neurons, suggesting that it is not toxic to nontransformed cells. The mechanism of action of apigenin seems to involve p53, as it increased the levels of p53 and the p53-induced gene products p21WAF1/CIP1 and Bax. Furthermore, apigenin (15-60 micromol/L) induced cell death and apoptosis of neuroblastoma cells expressing wild-type but not mutant p53. Apigenin increased caspase-3 activity and PARP cleavage, and Z-VAD-FMK, a broad-spectrum caspase-3 inhibitor, rescued NUB-7 cells from apigenin-mediated apoptosis indicating that apigenin induced apoptosis in acaspase-dependent manner. Overexpression of Bcl-X(L) rescued NUB-7 from apigenin-induced cell death, suggesting that Bax activity is important for the action of apigenin. Apigenin is thus a candidate therapeutic for neuroblastoma that likely acts by regulating a p53-Bax-caspase-3 apoptotic pathway.
Torkin
Risa
R
Cancer Research Program, The Hospital for Sick Children, 555 University Avenue, Toronto, Ontario, Canada, M5G 1X8.
Lavoie
Jean-François
JF
Kaplan
David R
DR
Yeger
Herman
H
D000590:Amino Acid Chloromethyl Ketones / Q000494:pharmacology; D000818:Animals; D047310:Apigenin / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects* / Q000502:physiology; D020169:Caspases / Q000378:metabolism*; D018797:Cell Cycle Proteins / Q000235:genetics; D002455:Cell Division / Q000187:drug effects; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects*; D003114:Colony-Forming Units Assay; D050759:Cyclin-Dependent Kinase Inhibitor p21; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D006801:Humans; D051379:Mice; D016688:Mice, Inbred NOD; D016513:Mice, SCID; D009447:Neuroblastoma / Q000473:pathology*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000235:genetics; D014183:Transplantation, Heterologous; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism*; D051028:bcl-2-Associated X Protein
D000590:Amino Acid Chloromethyl Ketones; C494826:BAX protein, human; C494827:Bax protein, mouse; C493956:CDKN1A protein, human; C493957:Cdkn1a protein, mouse; D018797:Cell Cycle Proteins; D050759:Cyclin-Dependent Kinase Inhibitor p21; D015853:Cysteine Proteinase Inhibitors; D019253:Proto-Oncogene Proteins c-bcl-2; D016159:Tumor Suppressor Protein p53; D051028:bcl-2-Associated X Protein; C096713:benzyloxycarbonylvalyl-alanyl-aspartyl fluoromethyl ketone; D047310:Apigenin; D020169:Caspases