Curcumin inhibits the mammalian target of rapamycin-mediated signaling pathways in cancer cells.
Curcumin (diferuloylmethane), a polyphenol natural product of the plant Curcuma longa, is undergoing early clinical trials as a novel anticancer agent. However, the anticancer mechanism of curcumin remains to be elucidated. Here we show that curcumin inhibited growth of rhabdomyosarcoma cells (Rh1 and Rh30) (IC50 = 2-5 microM) and arrested cells in G1 phase of the cell cycle. Curcumin also induced apoptosis and inhibited the basal or type I insulin-like growth factor-induced motility of the cells. At physiological concentrations (2.5 microM), curcumin rapidly inhibited phosphorylation of the mammalian target of rapamycin (mTOR) and its downstream effector molecules, p70 S6 kinase 1 (S6K1) and eukaryotic initiation factor 4E (eIF4E) binding protein 1 (4E-BP1), in a panel of cell lines (Rh1, Rh30, DU145, MCF-7 and Hela). Curcumin also inhibited phosphorylation of Akt in the cells, but only at high concentrations (>40 microM). The data suggest that curcumin may execute its anticancer activity primarily by blocking mTOR-mediated signaling pathways in the tumor cells.
Department of Biochemistry and Molecular Biology and Feist-Weiller Cancer Center, Louisiana State University Health Sciences Center, Shreveport, LA 71130-3932, USA.
Christopher S
CS
Beevers
Fengjun
F
Li
Lei
L
Liu
Shile
S
Huang
D048868:Adaptor Proteins, Signal Transducing / Q000378:metabolism; D018797:Cell Cycle Proteins; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D003474:Curcumin / Q000494:pharmacology*; D016193:G1 Phase / Q000187:drug effects; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology; D010750:Phosphoproteins / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D008517:Phytotherapy; D011494:Protein Kinases / Q000378:metabolism*; D016192:Resting Phase, Cell Cycle / Q000187:drug effects; D012208:Rhabdomyosarcoma / Q000188:drug therapy* / Q000378:metabolism* / Q000473:pathology; D019893:Ribosomal Protein S6 Kinases / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects*; D058570:TOR Serine-Threonine Kinases; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism
D048868:Adaptor Proteins, Signal Transducing; D018797:Cell Cycle Proteins; C087000:EIF4EBP1 protein, human; D010750:Phosphoproteins; D016159:Tumor Suppressor Protein p53; D007334:Insulin-Like Growth Factor I; D011494:Protein Kinases; C546842:MTOR protein, human; D019893:Ribosomal Protein S6 Kinases; D058570:TOR Serine-Threonine Kinases; D003474:Curcumin