Statistical analysis was performed with PASW 17 (SPSS Inc., Chicago Ill) software. results obtained using estrogen-deprived then beta-estradiol stimulated cells and antibody 1.1 (tab-delimited text file). 1471-2407-11-30-S4.TXT (212K) GUID:?1F51CA23-A13A-4ED0-86C7-47CF68CD658D Additional file 5 The ChIP-on-chip results obtained using estrogen-deprived then beta-estradiol stimulated cells and antibody 1493 (tab-delimited text file). 1471-2407-11-30-S5.TXT (217K) GUID:?03097B8E-AB96-4F5C-8A05-3EC444078319 Additional file 6 The merged ChIP-on-chip data with the gene annotations (tab-delimited text file). The natural ChIP on chip data has been deposited in the NCBI GEO database (GEO:”type”:”entrez-geo”,”attrs”:”text”:”GSE18706″,”term_id”:”18706″GSE18706). 1471-2407-11-30-S6.TXT (905K) GUID:?83B47604-0437-49F3-BD8A-3071F2DEA101 Abstract Background The c-Myb transcription factor regulates differentiation and proliferation in hematopoietic cells, stem cells and epithelial cells. Although oncogenic versions of c-Myb were first associated with leukemias, over expression or rearrangement of the c- em myb /em gene is usually common in several types of solid tumors, including breast cancers. Expression of the c- em myb /em gene in human breast cancer cells is dependent on estrogen stimulation, but little is 4-Aminosalicylic acid known about the activities of the c-Myb protein or what genes it regulates in estrogen-stimulated cells. Methods We used chromatin immunoprecipitation coupled with whole genome promoter tiling microarrays to identify endogenous c-Myb target genes in 4-Aminosalicylic acid human MCF-7 breast malignancy cells and characterized the activity of c-Myb at a panel of target genes during 4-Aminosalicylic acid different stages of estrogen deprivation and stimulation. Results By using different antibodies and different growth conditions, the c-Myb protein was found associated with over 10,000 promoters in MCF-7 cells, including many genes that encode cell cycle regulators or transcription factors and more than 60 genes that encode microRNAs. Several previously identified c-Myb target genes were identified, including CCNB1, MYC and CXCR4 and novel targets such as JUN, KLF4, NANOG and SND1. By studying a panel of these targets to validate the results, we found that estradiol stimulation brought on the association of c-Myb with promoters and that association correlated with increased target gene expression. We studied one target gene, CXCR4, in detail, showing that c-Myb associated with the CXCR4 gene promoter and activated a CXCR4 reporter gene in transfection assays. Conclusions Our results show that c-Myb associates with a surprisingly large number of promoters in human cells. The results also suggest that estradiol stimulation leads to large-scale, genome-wide changes in c-Myb activity and subsequent changes in gene expression in human breast cancer cells. Background The importance of the c-Myb transcription factor in breast cancer is usually 4-Aminosalicylic acid closely linked to the response to estrogen [1]. Expression of the c- em IFITM1 myb /em (MYB) gene is usually associated with expression of estrogen receptors (ERs) in breast tumors [2,3]. (Note: We use c-Myb and c- em myb /em to distinguish between the protein and gene, respectively.) Regulation by ERs has been implicated in the post-transcriptional regulation of c- em myb /em gene expression [4] and the c- em myb /em gene is usually involved in recurrent translocations in some breast tumors that are positive for expression of ERs [5]. The c- em myb /em gene is usually induced by activation of ERs in breast malignancy cell lines such as MCF-7 [6-8] and c-Myb protein has been implicated in the regulation of several genes important in breast cancer development and progression, including BRCA1 [9], CXCL12 [10], Mdm2 and p53 [11]. Although the expression of c-Myb protein is usually important for estrogen-stimulated proliferation of breast malignancy cells [6], the functions of c-Myb and the target genes that it regulates in response to stimulation of ERs have yet to be identified. The c- em myb /em gene is usually a cellular proto-oncogene from which the v- em myb /em oncogenes expressed by two avian leukemia viruses are derived [12]. The v- em myb /em oncogenes transform hematopoietic cells in tissue culture and induce leukemias in animals, and a mouse knockout of c- em myb /em leads to severe hematopoietic defects [13], which has led many researchers to focus 4-Aminosalicylic acid on the role of the Myb proteins in hematopoietic cells. However, increasing evidence has demonstrated an important role for c-Myb expression in several epithelial cell types, including breast and colon [14,15] and there are examples where activated or rearranged.