Combination of Nimbolide and TNF-α-Increases Human Colon Adenocarcinoma Cell Death through JNK-mediated DR5 Up- regulation.
Tumor necrosis factor (TNF-α), an inflammatory cytokine that plays an important role in the control of cell proliferation, differentiation, and apoptosis, has previously been used in anti-cancer therapy. However, the therapeutic applications of TNF-α are largely limited due to its general toxicity and anti-apoptotic influence. To overcome this problem, the present study focused on the effect of active constituents isolated from a medicinal plant on TNF-α-induced apoptosis in human colon adenocarcinoma (HT-29) cells. Nimbolide from Azadirachta indica was evaluated for cytotoxicity by methyl tetrazolium 3-[4,5-dimethylthiazol-2-yl]-2, 5-diphenyltetrazolium bromide (MTT) assay and phase contrast microscopy. Effects on apoptotic signaling proteins were investigated using Western blot analysis. Nimbolide showed cytotoxicity against HT-29 cells that was significantly different from the control group (<0.01), a concentration of 10 μM significantly inducing cell death (<0.01). In combination with TNF-α, nimbolide significantly enhanced-induced cell death. In apoptotic pathway, nimbolide activated c-Jun N-terminal kinase (JNK) phosphorylation, BH3 interacting-domain death agonist (Bid) and up-regulated the death receptor 5 (DR5) level. In the combination group, nimbolide markedly sensitized TNF-α-induced JNK, Bid, caspase-3 activation and the up-regulation of DR5. Our findings overall indicate that nimbolide may enhance TNF-α-mediated cellular proliferation inhibition through increasing cell apoptosis of HT-29 cells by up-reglation of DR5 expression via the JNK pathway.
Faculty of Pharmaceutical Sciences, Khon Kaen University, Khon Kaen, Thailand E-mail : pwaiwut79@yahoo.com, porntip.w@ubu.ac.th.
Chantana
C
Chantana
Chavi
C
Yenjai
Prasert
P
Reubroycharoen
Pornthip
P
Waiwut
D000230:Adenocarcinoma; D017209:Apoptosis / Q000187:drug effects*; D015153:Blotting, Western; D049109:Cell Proliferation / Q000187:drug effects; D003110:Colonic Neoplasms / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology*; D004357:Drug Synergism; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects*; D006801:Humans; D048031:JNK Mitogen-Activated Protein Kinases / Q000378:metabolism*; D036701:Limonins / Q000494:pharmacology*; D053220:Receptors, TNF-Related Apoptosis-Inducing Ligand / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects; D014407:Tumor Cells, Cultured; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*; D015854:Up-Regulation
D036701:Limonins; D053220:Receptors, TNF-Related Apoptosis-Inducing Ligand; C505639:TNFRSF10B protein, human; D014409:Tumor Necrosis Factor-alpha; C042198:nimbolide; D048031:JNK Mitogen-Activated Protein Kinases