Molecular mechanisms of curcumin-induced cytotoxicity: induction of apoptosis through generation of reactive oxygen species, down-regulation of Bcl-XL and IAP, the release of cytochrome c and inhibition of Akt.
Curcumin, a natural, biologically active compound extracted from rhizomes of Curcuma species, has been shown to possess potent anti-inflammatory, anti-tumor and anti-oxidative properties. The mechanism by which curcumin initiates apoptosis remains poorly understood. In the present report we investigated the effect of curcumin on the activation of the apoptotic pathway in human renal Caki cells. Treatment of Caki cells with 50 microM curcumin resulted in the activation of caspase 3, cleavage of phospholipase C-gamma1 and DNA fragmentation. Curcumin-induced apoptosis is mediated through the activation of caspase, which is specifically inhibited by the caspase inhibitor, benzyloxycarbony-Val-Ala-Asp-fluoromethyl ketone. Curcumin causes dose-dependent apoptosis and DNA fragmentation of Caki cells, which is preceded by the sequential dephosphorylation of Akt, down-regulation of the anti-apoptotic Bcl-2, Bcl-XL and IAP proteins, release of cytochrome c and activation of caspase 3. Cyclosporin A, as well as caspase inhibitor, specifically inhibit curcumin-induced apoptosis in Caki cells. Pre-treatment with N-acetyl-cysteine, markedly prevented dephosphorylation of Akt, and cytochrome c release, and cell death, suggesting a role for reactive oxygen species in this process. The data indicate that curcumin can cause cell damage by inactivating the Akt-related cell survival pathway and release of cytochrome c, providing a new mechanism for curcumin-induced cytotoxicity.
Woo
Ju-Hyung
JH
Department of Immunology, School of Medicine, Keimyung University, 194 DongSan-Dong Jung-Gu, Taegu, 700-712, South Korea.
Kim
Young-Ho
YH
Choi
Yun-Jung
YJ
Kim
Dae-Gon
DG
Lee
Kyung-Seop
KS
Bae
Jae Hoon
JH
Min
Do Sik
DS
Chang
Jong-Soo
JS
Jeong
Yong-Jin
YJ
Lee
Young Han
YH
Park
Jong-Wook
JW
Kwon
Taeg Kyu
TK
D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D015153:Blotting, Western; D002292:Carcinoma, Renal Cell / Q000378:metabolism / Q000473:pathology; D020169:Caspases / Q000378:metabolism*; D003474:Curcumin / Q000494:pharmacology*; D003574:Cytochrome c Group / Q000378:metabolism*; D015536:Down-Regulation; D004789:Enzyme Activation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D016166:Free Radical Scavengers / Q000494:pharmacology; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D051034:Inhibitor of Apoptosis Proteins; D007680:Kidney Neoplasms / Q000378:metabolism / Q000473:pathology; D008928:Mitochondria / Q000187:drug effects; D011065:Poly(ADP-ribose) Polymerases / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases; D011506:Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000037:antagonists & inhibitors / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D017382:Reactive Oxygen Species; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014407:Tumor Cells, Cultured; D051028:bcl-2-Associated X Protein; D051020:bcl-X Protein
D000970:Antineoplastic Agents; C494811:BCL2L1 protein, human; D003574:Cytochrome c Group; D004791:Enzyme Inhibitors; D016166:Free Radical Scavengers; D051034:Inhibitor of Apoptosis Proteins; D011506:Proteins; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D012333:RNA, Messenger; D017382:Reactive Oxygen Species; D051028:bcl-2-Associated X Protein; D051020:bcl-X Protein; D011065:Poly(ADP-ribose) Polymerases; C494918:AKT1 protein, human; D017346:Protein Serine-Threonine Kinases; D051057:Proto-Oncogene Proteins c-akt; D020169:Caspases; D003474:Curcumin