Differential growth inhibition and induction of apoptosis by gossypol between HCT116 and HCT116/Bax(-/-) colorectal cancer cells.
1. Bax is a very important pro-apoptosis molecule. HCT116/Bax(-/-) cells do not express the pro-apoptosis Bcl-2 family member, Bax. In the present study, the anticancer effects of gossypol on HCT116 and HCT116/Bax(-/-) cells were compared in terms of inhibition of cell growth, inhibition of colony formation and induction of apoptosis. 2. Following treatment with concentrations more than 20 micromol/L gossypol, only slight differences (not significant) were seen between HCT116 and HCT116/Bax(-/-) cells in terms of the inhibition of cell growth and induction of apoptosis. No difference was seen in the inhibition of colony formation. Gossypol had no effect at concentrations < 2 micromol/L. The only effective concentration of gossypol to result in differences between HCT116 and HCT116/Bax(-/-) cells was 5 micromol/L. However, even at this concentration, Bax deficiency did not result in complete abolition of gossypol-induced growth inhibition or apoptosis. Exposure of cells to 5 micromol/L gossypol for 24 h did not cause any significant difference in the activation of caspase 2 between HCT116 and HCT116/Bax(-/-) cells; however, activation of caspase 3, 8 and 9 was significantly elevated in HCT116 cells, with the effect on caspase 3 activation being the greatest, compared with HCT116/Bax(-/-) cells. 3. These findings suggest that the contribution of Bax to gossypol-induced growth inhibition and apoptosis is dose dependent and that gossypol-induced apoptosis requires activation of caspase 3, 8, and 9.
Zhang
Manchao
M
Department of Biochemistry and Molecular Pharmacology and Mary Babb Rodalph Cancer Center, West Virginia University, Morgantown, West Virginia 26506-9142, USA. mzhang2@hsc.wvu.edu
Liu
Hongpeng
H
Tian
Zhenkun
Z
Huang
Jenny
J
Remo
Mylene
M
Li
Q Quentin
QQ
D017209:Apoptosis / Q000187:drug effects*; D015153:Blotting, Western; D020169:Caspases / Q000378:metabolism; D049109:Cell Proliferation / Q000187:drug effects; D003114:Colony-Forming Units Assay; D004305:Dose-Response Relationship, Drug; D019254:Genes, bcl-2 / Q000187:drug effects; D006072:Gossypol / Q000494:pharmacology*; D045325:HCT116 Cells; D006801:Humans; D030781:Organisms, Genetically Modified; D051028:bcl-2-Associated X Protein / Q000096:biosynthesis* / Q000235:genetics
D051028:bcl-2-Associated X Protein; D020169:Caspases; D006072:Gossypol