Alterations of BRMS1-ARID4A interaction modify gene expression but still suppress metastasis in human breast cancer cells.
The BRMS1 metastasis suppressor interacts with the protein AT-rich interactive domain 4A (ARID4A, RBBP1) as part of SIN3.histone deacetylase chromatin remodeling complexes. These transcriptional co-repressors regulate diverse cell phenotypes depending upon complex composition. To define BRMS1 complexes and their roles in metastasis suppression, we generated BRMS1 mutants (BRMS1(mut)) and mapped ARID4A interactions. BRMS1(L174D) disrupted direct interaction with ARID4A in yeast two-hybrid genetic screens but retained an indirect association with ARID4A in MDA-MB-231 and -435 human breast cancer cell lines by co-immunoprecipitation. Deletion of the first coiled-coil domain (BRMS1(DeltaCC1)) did not disrupt direct interaction in yeast two-hybrid screens but did prevent association by co-immunoprecipitation. These results suggest altered complex composition with BRMS1(mut). Although basal transcription repression was impaired and the pro-metastatic protein osteopontin was differentially down-regulated by BRMS1(L174D) and BRMS1(DeltaCC1), both down-regulated the epidermal growth factor receptor and suppressed metastasis in MDA-MB-231 and -435 breast cancer xenograft models. We conclude that BRMS1(mut), which modifies the composition of a SIN3.histone deacetylase chromatin remodeling complex, leads to altered gene expression profiles. Because metastasis requires the coordinate expression of multiple genes, down-regulation of at least one important gene, such as the epidermal growth factor receptor, had the ability to suppress metastasis. Understanding which interactions are necessary for particular biochemical/cellular functions may prove important for future strategies targeting metastasis.
Hurst
Douglas R
DR
Department of Pathology, University of Alabama, Birmingham, Alabama 35294, USA.
Xie
Yi
Y
Vaidya
Kedar S
KS
Mehta
Alka
A
Moore
Blake P
BP
Accavitti-Loper
Mary Ann
MA
Samant
Rajeev S
RS
Saxena
Ritu
R
Silveira
Alexandra C
AC
Welch
Danny R
DR
D000818:Animals; D001943:Breast Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D045744:Cell Line, Tumor; D042002:Chromatin Assembly and Disassembly / Q000235:genetics; D015536:Down-Regulation / Q000235:genetics; D066246:ErbB Receptors / Q000096:biosynthesis / Q000235:genetics; D005260:Female; D015972:Gene Expression Regulation, Neoplastic / Q000235:genetics; D006655:Histone Deacetylases / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D051379:Mice; D009154:Mutation; D009362:Neoplasm Metastasis; D009363:Neoplasm Proteins / Q000235:genetics / Q000378:metabolism*; D009368:Neoplasm Transplantation; D053495:Osteopontin / Q000096:biosynthesis / Q000235:genetics; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*; D056465:Retinoblastoma-Binding Protein 1; D056264:Sin3 Histone Deacetylase and Corepressor Complex; D014158:Transcription, Genetic / Q000235:genetics; D014183:Transplantation, Heterologous
C533431:Arid4a protein, mouse; C410024:BRMS1 protein, human; D002352:Carrier Proteins; D009363:Neoplasm Proteins; D012097:Repressor Proteins; D056465:Retinoblastoma-Binding Protein 1; D053495:Osteopontin; C512478:EGFR protein, human; D066246:ErbB Receptors; D006655:Histone Deacetylases; D056264:Sin3 Histone Deacetylase and Corepressor Complex