| Expression of P-glycoprotein in HeLa cells confers resistance to ceramide cytotoxicity. | |
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MedLine Citation:
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PMID: 21042729 Owner: NLM Status: In-Process |
Abstract/OtherAbstract:
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The role of glucosylceramide synthase (GCS) in regulating ceramide-induced apoptosis has been widely studied. The purpose of this investigation was to evaluate the role of P-glycoprotein (P-gp) in regulating ceramide cytotoxicity by using C6-ceramide. To accomplish this, we employed HeLa cells with conditional expression of the multidrug resistance gene 1/P-gp. HeLa cells expressing P-gp (P-gp/on cells) challenged with [14C]C6-ceramide (6 µM), synthesized 4.5-fold the amount of C6-glucosylceramide (GC) compared to HeLa cells with suppressed expression of P-gp (P-gp/off cells), whereas the generated levels of C6-sphingomyelin were almost equal (33 and 29% of intracellular 14C, respectively). Tamoxifen, a P-gp antagonist, decreased the C6-GC levels from 3.5-1.0% in the P-gp/off and from 17-2.8% of the total lipid 14C levels in the P-gp/on cells. Tamoxifen did not inhibit cell-free C6-GC synthesis in the P-gp/off or P-gp/on homogenates. However, a specific GCS inhibitor, ethylenedioxy-1-phenyl-2-hexadecanoylamino-3-pyrrolidino-1-propanol (ethylenedioxy-P4), blocked synthesis by 90%. In the cytotoxicity assays, the P-gp/off cells were sensitive to C6-ceramide and the P-gp/on cells were resistant. Resistance to C6-ceramide in the P-gp/on cells was reversed by tamoxifen but not by ethylenedioxy-P4. Experiments in another cervical cancer model showed that multidrug-resistant P-gp-rich KB-V1 cells synthesized 3-fold more C6-GC from C6-ceramide than the parental, P-gp-poor KB-3-1 cells, and whereas tamoxifen had no effect on the C6-GC synthesis in the KB-3-1 cells, it inhibited synthesis by 70% in the KB-V1 cells. This study demonstrates that P-gp potentiates C6-ceramide glycosylation and if antagonized augments C6-ceramide sensitivity, both features previously ascribed to GCS. We propose that P-gp can be an effective target for enhancing short-chain ceramide cytotoxicity in the treatment of drug-resistant cancer. |
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Authors:
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Jacqueline V Chapman; Valérie Gouazé-Andersson; Myles C Cabot |
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Publication Detail:
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Type: Journal Article; Research Support, N.I.H., Extramural; Research Support, Non-U.S. Gov't |
Journal Detail:
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Title: International journal of oncology Volume: 37 ISSN: 1791-2423 ISO Abbreviation: Int. J. Oncol. Publication Date: 2010 Dec |
Date Detail:
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Created Date: 2010-11-02 Completed Date: - Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 9306042 Medline TA: Int J Oncol Country: Greece |
Other Details:
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Languages: eng Pagination: 1591-7 Citation Subset: IM |
Affiliation:
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John Wayne Cancer Institute at Saint John's Health Center, Santa Monica, CA 90404, USA. |
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Descriptor/Qualifier:
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| Grant Support | |
ID/Acronym/Agency:
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CA143755/CA/NCI NIH HHS; GM77391/GM/NIGMS NIH HHS; R21 CA143755-02/CA/NCI NIH HHS |
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