Promoter methylation reduces C/EBPδ (CEBPD) gene expression in the SUM-52PE human breast cancer cell line and in primary breast tumors

Abstract

CCAAT/Enhancer Binding Proteins (C/EBPs) are a highly conserved family of leucine zipper proteins that regulate cell growth and differentiation. C/EBPdelta functions in the initiation and maintenance of mammary epithelial cell G(0) growth arrest and 'loss of function' alterations in C/EBPdelta gene expression have been reported in human breast cancer and in rodent carcinogen-induced mammary tumors. The molecular mechanism underlying reduced C/EBPdelta gene expression in mammary tumorigenesis, however, is unknown. In this report we demonstrate that C/EBPdelta gene expression is undetectable in the SUM-52PE human breast cancer cell line and that silencing of SUM-52PE C/EBPdelta gene expression is due to epigenetic promoter hypermethylation (26/27 CpGs methylated). The hypermethylated SUM-52PE C/EBPdelta gene promoter is associated with reduced levels of acetylated Histone H4, consistent with a closed, transcriptionally inactive chromatin conformation. Treatment with 5'-aza-cytidine and trichostatin A (TSA) re-activates cytokine-induced SUM-52PE C/EBPdelta gene expression. C/EBPdelta gene expression is reduced to virtually undetectable levels in 32% (18/57) of primary human breast tumors. Site-specific CpG methylation was observed in 33% (6/18) of the low C/EBPdelta expressing primary breast tumors. CpG methylation adjacent to the C/EBPdelta proximal promoter Sp1 site was associated with reduced C/EBPdelta expression in a primary breast cancer sample. Electromobility shift assays (EMSA) demonstrated a significant reduction in binding to oligos containing the CpG methylation 5' to the Sp1 binding site. These results demonstrate a direct link between C/EBPdelta gene promoter hyper- and site specific-methylation and reduced C/EBPdelta gene expression in breast cancer cell lines and primary breast tumors.

Eicosapentaenoic Acid Demethylates a Single CpG That Mediates Expression of Tumor Suppressor CCAAT/Enhancer-binding Protein δ in U937 Leukemia Cells

“…5). Our results are consistent with the site-specific CpG demethylation of C/EBP␦ proximal promoter in primary breast cancer (59). Moreover, evidence demonstrating gene promoter site-specific methylation as a mechanism of tumor suppressor gene silencing in various types of cancer cells has been reported (60,61).…”

The heterogeneity of meningioma revealed by multiparameter analysis: infiltrative and non-infiltrative clinical phenotypes

“…For several of these pinpointed genes, in the context of diverse specific tumors, downregulation has been correlated with increased invasiveness, tumor progression, or decreased apoptosis. This was already reported for ANXA7 (involved in calcium signaling) (20); CD63 (involved in signal transduction) (21); CEBPD, FOS, HES1, MSX1, TP73 and TSC22D1 (all playing a role at least in transcription) (22)(23)(24)(25)(26)(27); GLG1 (fibroblast growth factor receptor) (28); PLA2G2A (phospholipase activity) (29) and PTPN6 (protein tyrosine phosphatase activity) (30). These data may support the idea that a decreased expression of these genes might be consistent with cellular events that are relevant with the infiltrative behaviors of meningiomas.…”

HMDB and 5-AzadC Combination Reverses Tumor Suppressor CCAAT/Enhancer-Binding Protein Delta to Strengthen the Death of Liver Cancer Cells

“…Here, we demonstrated that inactivation of another inflammation-responsive factor, CEBPD, by the epigenetic E2F1/SUZ12/EZH2 axis contributes to liver tumorigenesis. Importantly, inactivation of CEBPD during cancer progression has been reported in breast cancer, cervical cancer, HCC, leukemia, and prostate cancer (16,39,40). In addition to the proapoptotic genes PPARG2 and GADD153 (41,42), our recent results suggested that CEBPD contributes to the transcriptional activation of procaspase-8 in prostate cancer (43).…”