Geraniin-mediated apoptosis by cleavage of focal adhesion kinase through up-regulation of Fas ligand expression in human melanoma cells.
Geraniin, a form of tannin separated from geranium, causes cell death through induction of apoptosis; however, cell death characteristics for geraniin have not yet been elucidated. Here, we investigated the mechanism of geraniin-induced apoptosis in human melanoma cells and demonstrated that geraniin was able to induce cell apoptosis in a concentration- and time-dependent manner. We also examined the signaling pathway related to geraniin-induced apoptosis. To clarify the relationship between focal adhesion kinase (FAK) and geraniin-induced apoptosis, we treated human melanoma cells with geraniin and found that this resulted dose- and time-dependent degradation in FAK. However, FAK cleavage was significantly inhibited when cells were pretreated with a selective inhibitor of caspase-3 (Ac-Asp-Glu-Val-Asp-CHO). Here, we demonstrated for the first time that geraniin triggered cell death by caspase-3-mediated cleavage of FAK. There were two possible mechanisms for activating caspase-3, mitochondria-mediated and receptor-mediated apoptosis. To confirm the geraniin-relevant signaling pathway, using immunoblot analysis we found that geraniin-induced apoptosis was associated with the up-regulation of Fas ligand expression, the activation of caspase-8, the cleavage of Bid, and the induction of cytochrome c release from mitochondria to the cytosol. Treatment with geraniin caused induction of caspase-3 activity in a dose- and time-dependent manner followed by proteolytic cleavage of poly-(ADP-ribose) polymerase, and DNA fragmentation factor 45. The geraniin-induced apoptosis may provide a pivotal mechanism for its cancer-chemopreventive action.
Lee
Jang-Chang
JC
Graduate institute of Pharmaceutical Chemistry, College of Pharmacy, China Medical University, Taichung, Taiwan.
Tsai
Chih-Yen
CY
Kao
Jung-Yie
JY
Kao
Ming-Ching
MC
Tsai
Shih-Chang
SC
Chang
Chih-Shiang
CS
Huang
Li-Jiau
LJ
Kuo
Sheng-Chu
SC
Lin
Jen-Kun
JK
Way
Tzong-Der
TD
D016588:Anticarcinogenic Agents / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects*; D051023:BH3 Interacting Domain Death Agonist Protein / Q000378:metabolism; D053181:Caspase 8 / Q000378:metabolism; D061945:Caspase Inhibitors; D045744:Cell Line, Tumor; D045304:Cytochromes c / Q000378:metabolism; D004789:Enzyme Activation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D053222:Fas Ligand Protein / Q000235:genetics*; D051416:Focal Adhesion Protein-Tyrosine Kinases / Q000378:metabolism*; D005960:Glucosides / Q000378:metabolism / Q000494:pharmacology*; D006801:Humans; D047348:Hydrolyzable Tannins / Q000378:metabolism / Q000494:pharmacology*; D008545:Melanoma / Q000378:metabolism*; D015854:Up-Regulation / Q000187:drug effects*
D016588:Anticarcinogenic Agents; D051023:BH3 Interacting Domain Death Agonist Protein; D061945:Caspase Inhibitors; D004791:Enzyme Inhibitors; D053222:Fas Ligand Protein; D005960:Glucosides; D047348:Hydrolyzable Tannins; C024603:Geraniin; D045304:Cytochromes c; D051416:Focal Adhesion Protein-Tyrosine Kinases; D053181:Caspase 8