[Effects of cinobufagin on apoptosis in U-2OS osteosarcomas cells].
OBJECTIVE
To investigate the effects of cinobufagin on the apoptosis in U-2OS osteosarcomas cells (U-2OS cells) and explore its potential mechanism.


METHODS
The cytostatic effects of cinobufagin (10, 20, 50, 100, 200, and 400 nmol/L) on U-2OS cells were evaluated by MTT assay at 24, 48, and 72 hours after culture; simple U-2OS cells served as control group. The impact of cinobufagin (100 nmol/L) on the apoptosis in U-2OS cells was determined by flow cytometry at 48 hours after culture, which were treated with cinobufagin (experimental group) or with cinobufagin plus Z-VAD-FMK (control group), and simple U-2OS cells served as blank control group. The Caspase-3 activity was measured by Caspase-3 activity assay kit at 48 hours after culture, which were treated with cinobufagin (20, 50, and 100 nmol/L), and simple U-2OS cells served as control group. The expression of apoptosis signal pathway related proteins in U-2OS cells treated with cinobufagin were detected by Western blot at 48 hours after culture, which were treated with cinobufagin (20, 50, and 100 nmol/L), and simple U-2OS cells served as control group.


RESULTS
The results of MTT assay showed that cinobufagin inhibited the proliferation of U-2OS cells in a dose- and time-dependent manners. At each time point, the growth rate of U-2OS cells was significantly reduced with the increasing cinobufagin concentration, and as time prolonged, the growth rate of U-2OS cells behaved the same way in the same group. There were significant differences among different time points and groups (P < 0.05). The apoptotic rate of experimental group (46.87% +/- 11.23%) was significantly higher than that of the control group (2.34% +/- 0.98%) and blank control group (1.04% +/- 0.25%) (P < 0.05). The Caspase-3 activity in 20, 50, and 100 nmol/L groups were 1.14 +/- 0.32, 1.31 +/- 0.41, and 1.92 +/- 0.54, respectively, which were significantly higher than that in control group (P < 0.05). Compared with 20and 50 nmol/L groups, 100 nmol/L group significantly increased the Caspase-3 activity in U-2OS cells (P < 0.05). Compared with the control group, the expressions of cleaved Caspase-3, cleaved Caspase-9, and Bax were obviously up-regulated; the Bcl-2 expression was down-regulated; and the ratio of Bax/Bcl-2 was increased in different cinobufagin-treated groups (P < 0.05). The same tendency was seen in different cinobufagin-treated goups, showing significant differences among groups (P < 0.05).


CONCLUSIONS
Cinobufagin can inhibite the proliferation of U-2OS cells, and induce cell apoptosis. The potential mechanism of cinobufagin-induced apoptosis may be related to the mitochondria-mediated pathway.
Fei
F
Cao
Xiaohong
X
Kang
Lifang
L
Wang
D000590:Amino Acid Chloromethyl Ketones / Q000008:administration & dosage / Q000494:pharmacology; D000818:Animals; D000970:Antineoplastic Agents / Q000008:administration & dosage / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D002018:Bufanolides / Q000008:administration & dosage / Q000494:pharmacology*; D053148:Caspase 3 / Q000378:metabolism; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D005434:Flow Cytometry; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D006801:Humans; D008419:Materia Medica / Q000008:administration & dosage / Q000494:pharmacology*; D012516:Osteosarcoma / Q000378:metabolism / Q000473:pathology*; D051028:bcl-2-Associated X Protein / Q000378:metabolism
D000590:Amino Acid Chloromethyl Ketones; D000970:Antineoplastic Agents; C494826:BAX protein, human; D002018:Bufanolides; D008419:Materia Medica; D051028:bcl-2-Associated X Protein; C505407:CASP3 protein, human; D053148:Caspase 3; C002471:cinobufagin