Jacqueline V Chapman, Valérie Gouazé-Andersson, Maria C Messner, Margaret Flowers, Ramin Karimi, Mark Kester, Brian M Barth, Xin Liu, Yong-Yu Liu, Armando E Giuliano, Myles C Cabot
John Wayne Cancer Institute at Saint John's Health Center, Department of Experimental Therapeutics, 2200 Santa Monica Boulevard, Santa Monica, CA 90404, USA.
Biochemical pharmacology 2010 Aug 1Due to recent use of short-chain ceramides in preclinical studies, we characterized C6-ceramide metabolism in cancer cell lines and assessed metabolic junctures for enhancing efficacy. MDA-MB-231 breast cancer cells decreased the amount of C6-ceramide metabolized to C6-sphingomyelin (C6-SM) and increased the amount metabolized to C6-glucosylceramide (C6-GC) in response to increasing concentrations. A similar trend was seen in DU-145 (prostate cancer), PANC-1 (pancreatic cancer), and LoVo (colorectal cancer) cells. KG-1 leukemia cells favored C6-SM synthesis at low (0.6muM) and high-dose (12muM) C6-ceramide. Partnering C6-ceramide with tamoxifen, a P-glycoprotein antagonist that impedes ceramide glycosylation, was an effective regimen for enhancing cytotoxicity in cells. Experiments to assess the mechanism of cell death using KG-1 cells showed that tamoxifen inhibited synthesis of C6-GC and C6-SM from C6-ceramide by 80% and 50%, respectively, which was accompanied by enhanced apoptosis. Radiolabeling of KG-1 cells with [(3)H]palmitic acid produced a 2-fold increase in (3)H-long-chain ceramides when unlabeled C6-ceramide was added and a 9-fold increase when C6-ceramide and tamoxifen were added. The increase in (3)H-palmitate radiolabeling of long-chain ceramides was blocked by inclusion of a ceramide synthase inhibitor; however, inhibiting synthesis of long-chain ceramide did not rescue cells. These studies show that tamoxifen enhances the apoptotic effects of C6-ceramide. The proposed mechanism involves blocking short-chain ceramide anabolism to favor hydrolysis and generation of sphingosine. We propose that use of tamoxifen and other P-glycoprotein antagonists can be an effective means for enhancing cytotoxic potential of short-chain ceramides in the treatment of cancer. Copyright (c) 2010 Elsevier Inc. All rights reserved.
Jacqueline V Chapman, Valérie Gouazé-Andersson, Maria C Messner, Margaret Flowers, Ramin Karimi, Mark Kester, Brian M Barth, Xin Liu, Yong-Yu Liu, Armando E Giuliano, Myles C Cabot. Metabolism of short-chain ceramide by human cancer cells--implications for therapeutic approaches. Biochemical pharmacology. 2010 Aug 1;80(3):308-15
PMID: 20385104
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