ABSTRACT
An amendment to this paper has been published and can be accessed via the original article.
ABSTRACT
Curcumin, a natural polyphenolic compound, has commonly been used as a food additive or in many traditional medicine remedies for over 2,000 years in many Asian countries. Melatonin is a hormone secreted from pineal glands of mammals and possesses diverse physiological functions. Both curcumin and melatonin have the effective potential to inhibit proliferation of various types of cancers, but there is no report on their combination for bladder cancer treatment, and the underlying mechanism remains poorly understood. In the present study, we investigated whether the combination of curcumin and melatonin leads to an enhanced inhibition of cell proliferation in bladder cancer cells. Our results showed that the combinational treatment enhanced the repression of nuclear translocation of NF-κB and their binding on COX-2 promoter via inhibiting IKKß activity, resulting in inhibition of COX-2 expression. In addition, combined treatment with curcumin and melatonin induced cell apoptosis in bladder cancer through enhancing the release of cytochrome c from the mitochondrial intermembrane space into the cytosol. These results, therefore, indicated that melatonin synergized the inhibitory effect of curcumin against the growth of bladder cancer by enhancing the anti-proliferation, anti-migration, and pro-apoptotic activities, and provide strong evidence that combined treatment with curcumin and melatonin might exhibit an effective therapeutic option in bladder cancer therapy.
Subject(s)
Antineoplastic Combined Chemotherapy Protocols/pharmacology , Curcumin/pharmacology , Cyclooxygenase 2/metabolism , I-kappa B Kinase/antagonists & inhibitors , Melatonin/pharmacology , NF-kappa B/antagonists & inhibitors , Urinary Bladder Neoplasms/drug therapy , Animals , Cell Cycle Checkpoints/drug effects , Cell Line, Tumor , Cell Proliferation/drug effects , Curcumin/administration & dosage , Cyclooxygenase 2 Inhibitors/pharmacology , Drug Synergism , Heterografts , Humans , I-kappa B Kinase/metabolism , Male , Melatonin/administration & dosage , Mice , Mice, Inbred BALB C , Mice, Nude , NF-kappa B/metabolism , Random Allocation , Signal Transduction/drug effects , Urinary Bladder Neoplasms/metabolismABSTRACT
BACKGROUND: Glioblastoma multiforme (GBM) is one of the most refractory and palindromic central nervous system (CNS) neoplasms, and current treatments have poor effects in GBM patients. Hence, the identification of novel therapeutic targets and the development of effective treatment strategies are essential. Alantolactone (ATL) has a wide range of pharmacological activities, and its anti-tumor effect is receiving increasing attention. However, the molecular mechanism underlying the anti-GBM activity of ATL remains poorly understood. METHODS: The biological functions of ATL in GBM cells were investigated using migration/invasion, colony formation and cell cycle/apoptosis assays. The localization of nuclear factor kappa B (NF-κB) p50/p65 and its binding to the cyclooxygenase 2 (COX-2) promoter were determined using confocal immunofluorescence, a streptavidin-agarose pulldown assay and a chromatin immunoprecipitation (ChIP) assay. IKKß kinase activity was determined using a cell IKKß kinase activity spectrophotometry quantitative detection kit and a molecular docking study. LC-MS/MS analysis was performed to determine the ability of ATL to traverse the blood-brain barrier (BBB). The in vivo anti-tumor efficacy of ATL was also analyzed in xenografted nude mice. Western blot analysis was performed to detect the protein expression levels. RESULTS: ATL significantly suppressed the growth of GBM in vivo and in vitro. ATL significantly reduced the expression of COX-2 by inhibiting the kinase activity of IKKß by targeting the ATP-binding site and then attenuating the binding of NF-κB to the COX-2 promoter region. Furthermore, ATL induced apoptosis by activating the cytochrome c (cyt c)/caspase cascade signaling pathway. Moreover, ATL could penetrate the BBB. CONCLUSIONS: ATL exerts its anti-tumor effects in human GBM cells at least in part via NF-κB/COX-2-mediated signaling cascades by inhibiting IKKß kinase activity. ATL, which is a natural small molecule inhibitor, is a promising candidate for clinical applications in the treatment of CNS tumors.
