Mitochondrial perturbation, oxidative stress and lysosomal destabilization are involved in 7beta-hydroxysitosterol and 7beta-hydroxycholesterol triggered apoptosis in human colon cancer cells.
We reported previously that 7beta-hydroxysitosterol and 7beta-hydroxycholesterol induced apoptosis in Caco-2 cells. Apoptosis caused by 7beta-hydroxysitosterol but not by 7beta-hydroxycholesterol was related to a caspase-dependent process. In the present report, we compared the effects of both compounds on mitochondria integrity and on various modulators of apoptosis. When Caco-2 cells were exposed to both hydroxysterols, no changes in Bcl-2 and Bax expressions were detected indicating a Bcl-2/Bax-independent cell death pathway, whereas loss of mitochondrial membrane potential and cytochrome c release were observed. Endonuclease G expression and enhanced production of reactive oxygen species were detected in 7beta-hydroxycholesterol treated cells, but not with 7beta-hydroxysitosterol. Loss of mitochondrial membrane potential and cell death produced by both hydroxysterols were prevented by vitamin C. Lysosomal membrane integrity was altered with both hydroxysterols, but 7beta-hydroxysitosterol was significantly more active on than 7beta-hydroxycholesterol. Both hydroxysterols induced apoptosis by mitochondrial membrane permeabilization. However, 7beta-hydroxycholesterol exhibited a specific enhancement of oxidative stress and of endonuclease G expression despite its closely related chemical structure with 7beta-hydroxysitosterol. The two hydroxysterols exhibit different lipophilic properties which may explain their different biological effects.
Roussi
Stamatiki
S
INSERM U682, Université Louis Pasteur EA3430, IRCAD, 1, place de l'Hôpital, BP406, 67091, Strasbourg-Cedex, France. roussi@ulp.u-strasbg.fr
Gossé
Francine
F
Aoudé-Werner
Dalal
D
Zhang
Xin
X
Marchioni
Eric
E
Geoffroy
Philippe
P
Miesch
Michel
M
Raul
Francis
F
D017209:Apoptosis / Q000187:drug effects* / Q000502:physiology*; D001205:Ascorbic Acid / Q000494:pharmacology; D018938:Caco-2 Cells; D003110:Colonic Neoplasms / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology*; D045304:Cytochromes c / Q000378:metabolism; D004706:Endodeoxyribonucleases / Q000378:metabolism; D006801:Humans; D006888:Hydroxycholesterols / Q000494:pharmacology*; D008247:Lysosomes / Q000187:drug effects / Q000378:metabolism; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism; D018384:Oxidative Stress / Q000187:drug effects; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D012855:Sitosterols / Q000494:pharmacology*; D051028:bcl-2-Associated X Protein / Q000378:metabolism
C494826:BAX protein, human; D006888:Hydroxycholesterols; D019253:Proto-Oncogene Proteins c-bcl-2; D017382:Reactive Oxygen Species; D012855:Sitosterols; D051028:bcl-2-Associated X Protein; C011486:hydroxysitosterol; C011724:cholest-5-en-3 beta,7 alpha-diol; D045304:Cytochromes c; D004706:Endodeoxyribonucleases; C052391:endonuclease G; D001205:Ascorbic Acid