Aloe emodin-induced apoptosis in t-HSC/Cl-6 cells involves a mitochondria-mediated pathway.
The aim of our study was to clarify the apoptosis pathway induced by aloe emodin, an hydroxyanthraquinone present in aloe vera leaves, in rat hepatic stellate cells transformed by simian virus 40 (t-HSC/Cl-6), which retain the features of activated rat stellate cells. Apoptosis was determined by DNA fragmentation, caspase activity assay and western blotting analysis. Treatment of t-HSC/Cl-6 cells with 12.5, 25, or 50 microM aloe emodin inhibited t-HSC/Cl-6 cell viability in a dose- and time-dependent manner. The induction of apoptosis by aloe emodin was confirmed by typical DNA ladder formation and annexin v-propidium iodide flow-cytometric analysis. Aloe emodin treatment of t-HSC/Cl-6 cells caused activation of caspase-3 and caspase-9, detected with a caspase activity assay, although no change was observed in caspase-8 activity. Western blotting showed caspase-3 and caspase-9 active forms and the subsequent proteolytic cleavage of poly(ADP-ribose) polymerase. Aloe emodin induced mitochondrial membrane depolarization. Our data also show that cytochrome c increased in the cytosol but decreased in the mitochondria in a time-dependent manner. Increased Bax and unchanged Bcl-2 levels resulted in an increased Bax/Bcl-2 ratio. Thus, our research provides evidence that aloe emodin-induced apoptosis involves a mitochondria-associated apoptosis pathway.
Lian
Li-Hua
LH
Department of Pharmacy, Wonkwang University, Iksan, Jeonbuk 570-749, Republic of Korea.
Park
Eun-Jeon
EJ
Piao
Hui-Shan
HS
Zhao
Yu-Zhe
YZ
Sohn
Dong Hwan
DH
D000818:Animals; D000880:Anthraquinones; D017209:Apoptosis; D053148:Caspase 3; D053453:Caspase 9; D020169:Caspases / Q000378:metabolism; D002460:Cell Line; D049109:Cell Proliferation / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D045304:Cytochromes c / Q000378:metabolism; D053938:DNA Fragmentation; D004642:Emodin / Q000494:pharmacology*; D008564:Membrane Potentials / Q000187:drug effects; D008928:Mitochondria / Q000187:drug effects* / Q000378:metabolism / Q000502:physiology; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D051381:Rats; D051028:bcl-2-Associated X Protein
D000880:Anthraquinones; C494828:Bax protein, rat; D019253:Proto-Oncogene Proteins c-bcl-2; D051028:bcl-2-Associated X Protein; D045304:Cytochromes c; C518327:aloe emodin; C505410:Casp3 protein, rat; C506435:Casp9 protein, rat; D053148:Caspase 3; D053453:Caspase 9; D020169:Caspases; D004642:Emodin