Hyaluronan-mediated CD44 Interaction with p300 and SIRT1 Regulates β-Catenin Signaling and NFκB-specific Transcription Activity Leading to MDR1 and Bcl-xL Gene Expression and Chemoresistance in Breast Tumor Cells*
- Department of Medicine, Endocrine Unit (111N2), University of California at San Francisco and Veterans Affairs Medical Center, San Francisco, California 94121
- 1 Veterans Affairs Research Career Scientist. To whom correspondence and reprint requests should be addressed: Endocrine Unit (111N), Dept. of Medicine, University of California at San Francisco and Veterans Affairs Medical Center, 4150 Clement St., San Francisco, CA 94121. Tel.: 415-221-4810, ext. 3321; Fax: 415-383-1638; E-mail: lilly.bourguignon{at}ucsf.edu.
Abstract
In this study we have investigated hyaluronan (HA)-mediated CD44 (an HA receptor) interactions with p300 (a histone acetyltransferase) and SIRT1 (a histone deacetylase) in human breast tumor cells (MCF-7 cells). Specifically, our results indicate that HA binding to CD44 up-regulates p300 expression and its acetyltransferase activity that, in turn, promotes acetylation of β-catenin and NFκB-p65 leading to activation of β-catenin-associated T-cell factor/lymphocyte enhancer factor transcriptional co-activation and NFκB-specific transcriptional up-regulation, respectively. These changes then cause the expression of the MDR1 (P-glycoprotein/P-gp) gene and the anti-apoptotic gene Bcl-xL resulting in chemoresistance in MCF-7 cells. Our data also show that down-regulation of p300, β-catenin, or NFκB-p65 in MCF-7 cells (by transfecting cells with p300-, β-catenin-, or NFκB-p65-specific small interfering RNA) inhibits the HA/CD44-mediated β-catenin/NFκB-p65 acetylation and abrogates the aforementioned transcriptional activities. Subsequently, there is a significant decrease in both MDR1 and Bcl-xL gene expression and an enhancement in caspase-3 activity and chemosensitivity in the breast tumor cells. Further analyses indicate that activation of SIRT1 (deacetylase) by resveratrol (a natural antioxidant) induces SIRT1-p300 association and acetyltransferase inactivation, leading to deacetylation of HA/CD44-induced β-catenin and NFκB-p65, inhibition of β-catenin-T-cell factor/lymphocyte enhancer factor and NFκB-specific transcriptional activation, and the impairment of MDR1 and Bcl-xL gene expression. All these multiple effects lead to an activation of caspase-3 and a reduction of chemoresistance. Together, these findings suggest that the interactions between HA/CD44-stimulated p300 (acetyltransferase) and resveratrol-activated SIRT1 (deacetylase) play pivotal roles in regulating the balance between cell survival versus apoptosis, and multidrug resistance versus sensitivity in breast tumor cells.
Footnotes
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↵2 The abbreviations used are: HA, hyaluronan; HAT, histone acetyltransferase; HDAC, histone deacetylase; TCF/LEF, T-cell factor/lymphocyte enhancer factor; siRNA, small interfering RNA; Z, benzyloxycarbonyl; FMK, fluoromethyl ketone; Q-PC, quantitative PCR; IKK, inhibitor of κB kinase; MDR, multidrug resistance.
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↵* This work was supported, in whole or in part, by National Institutes of Health Grants R01 CA66163, R01 CA 78633, and P01 AR39448 (USPHS). This work was also supported by a Veterans Affairs merit review grant and a Department of Defense grant. The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
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- Received August 29, 2008.
- Revision received November 10, 2008.
- The American Society for Biochemistry and Molecular Biology, Inc.
