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Department of Surgery, University of Virginia School of Medicine, Charlottesville, Virginia
Received 26 May 2006/ Returned for modification 1 August 2006/ Accepted 11 September 2006
The antiapoptotic transcription factor NF-
B is constitutively activated in many cancers and is important for cytokine-mediated progression and metastatic movement of tumors. Breast cancer metastasis suppressor 1 (BRMS1) is a metastasis suppressor gene whose mechanisms of action are poorly understood. In this report, we demonstrate that BRMS1 decreases the transactivation potential of RelA/p65 and ameliorates the expression of NF-
B-regulated antiapoptotic gene products. BRMS1 immunoprecipitates with the RelA/p65 subunit of NF-
B with protein-protein interactions occurring at the C terminus region of the rel homology domain but not at its known transactivation domains. Moreover, BRMS1 functions as a corepressor by promoting binding of HDAC1 to RelA/p65, where it deacetylates lysine K310 on RelA/p65, which suppresses RelA/p65 transcriptional activity. Selective small interfering RNA knockdown of BRMS1 confirms that chromatin-bound BRMS1 is required for deacetylation of RelA/p65, while enhancing chromatin occupancy of HDAC1 onto the NF-
B-regulated promoters cIAP2 and Bfl-1/A1. We observed in cells lacking BRMS1 a dramatic increase in cell viability after the loss of attachment from the extracellular matrix. Collectively, these results suggest that BRMS1 suppresses metastasis through its ability to function as a transcriptional corepressor of antiapoptotic genes regulated by NF-
B.
Published ahead of print on 25 September 2006.
Supplemental material for this article may be found at http://mcb.asm.org/.
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