Estrogens and Progesterone Promote Persistent CCND1 Gene Activation during G₁ by Inducing Transcriptional Derepression via c-Jun/c-Fos/Estrogen Receptor (Progesterone Receptor) Complex Assembly to a Distal Regulatory Element and Recruitment of Cyclin D1 to Its Own Gene Promoter

Abstract

Transcriptional activation of the cyclin D1 gene (CCND1) plays a pivotal role in G 1 -phase progression, which is thereby controlled by multiple regulatory factors, including nuclear receptors (NRs). Appropriate CCND1 gene activity is essential for normal development and physiology of the mammary gland, where it is regulated by ovarian steroids through a mechanism(s) that is not fully elucidated. We report here that CCND1 promoter activation by estrogens in human breast cancer cells is mediated by recruitment of a c-Jun/c-Fos/estrogen receptor ␣ complex to the tetradecanoyl phorbol acetate-responsive element of the gene, together with Oct-1 to a site immediately adjacent. This process coincides with the release from the same DNA region of a transcriptional repressor complex including Yin-Yang 1 (YY1) and histone deacetylase 1 and is sufficient to induce the assembly of the basal transcription machinery on the promoter and to lead to initial cyclin D1 accumulation in the cell. Later on in estrogen stimulation, the cyclin D1/Cdk4 holoenzyme associates with the CCND1 promoter, where E2F and pRb can also be found, contributing to the long-lasting gene enhancement required to drive G 1 -phase completion. Interestingly, progesterone triggers similar regulatory events through its own NRs, suggesting that the gene regulation cascade described here represents a crossroad for the transcriptional control of G 1 -phase progression by different classes of NRs.Mammary gland morphogenesis and development result from the interplay of genetic and epigenetic pathways, controlled by hormones, growth factors, and other signaling molecules. Derangement of one or more of these regulatory pathways results in the abnormal growth and differentiation of mammary epithelial cells, leading to breast carcinogenesis. The ovarian hormones estrogen and progesterone promote mammary gland differentiation toward the female phenotype at the onset of puberty and control breast tropism and function throughout the reproductive life by affecting epithelial cell proliferation. Mammary gland cells are endowed with highaffinity receptors for these steroids (estrogen receptor ␣ [ER␣] and ER␤ and progesterone receptor A [PR-A] and PR-B, respectively), which belong to the nuclear receptor (NR) family of transcription factors (31

Cyclin D1 Is Transcriptionally Down-Regulated by ZO-2 via an E Box and the Transcription Factor c-Myc

“…Inside the region located between nucleotides (nt) Ϫ737/ Ϫ730 (distal) or between nt Ϫ143/Ϫ133 (proximal), there are elements recognized by the transcription factors of the E2F family (Fukami-Kobayashi and Mitsui, 1998;Watanabe et al, 1998;Cicatiello et al, 2004). Because ChIP assays (Cicatiello et al, 2004) have revealed that E2F factors bind to DNA in a cell cycle progression-related manner, we next performed deletions of the E2F region, and we designed functional assays to test the particular relevance of these transcription factors in controlling the cyclin D1 promoter activity under ZO-2 effect.…”

“…The pXP2-CD1 reporter vector contains the cyclin D1 regulatory region here shown. TRE(AP-1), TRE, Ϫ924 to Ϫ938 (Herber et al, 1994); dE2F, distal E2F, Ϫ730 to Ϫ737 (Herber et al, 1994); E box, bHLH, and Zn finger transcription factors binding site, Ϫ547 to Ϫ553 (Herber et al, 1994); ZONAB, ZONAB binding site and inverted CCAAT box, Ϫ527 to Ϫ532 (Sourisseau et al, 2006); Oct, Oct binding site, Ϫ646 to Ϫ652 (Cicatiello et al, 2004); pE2F, proximal E2F, Ϫ133 to Ϫ143 (Watanabe et al, 1998); Tcf/Lef, Tcf/Lef binding site, Ϫ67 to Ϫ77 (Shtutman et al, 1999); CRE, Ϫ46 to Ϫ53, (Herber et al, 1994); and Start, site of transcription initiation, Ϫ1/ϩ1 (Herber et al, 1994). Broken arrow stands for the transcription start point.…”

“…Because ChIP assays (Cicatiello et al, 2004) have revealed that E2F factors bind to DNA in a cell cycle progression-related manner, we next performed deletions of the E2F region, and we designed functional assays to test the particular relevance of these transcription factors in controlling the cyclin D1 promoter activity under ZO-2 effect. In accordance with the results found in other cell lines (Watanabe et al, 1998), the deleted distal "E2F" region seemed to contain a silencer element for the cyclin D1 promoter ( Figure 4B).…”

Impaired p53 function leads to centrosome amplification, acquired ERα phenotypic heterogeneity and distant metastases in breast cancer MCF-7 xenografts

“…Among estrogens, 17-b estradiol is the major promoter of cell proliferation in both normal and neoplastic breast tissue through its binding to the highaffinity estrogen receptor (ERa). ERa functions as an estrogen-activated transcription factor and mediates the expression of target genes involved in the regulation of cell proliferation and inhibition of apoptosis of the breast epithelium (Cicatiello et al, 2004;Helguero et al, 2005). Excessive activation of the ERa pathway due to increased hormonal secretion, prolonged estrogen exposure or increased levels of the receptor may lead to increased risk to develop breast cancer (Calaf, 2006;Lee et al, 2006).…”

A cell-type-specific transcriptional network required for estrogen regulation of cyclin D1 and cell cycle progression in breast cancer

“…Transient transfection-based studies have mapped several potential estrogen-responsive sites in the CCND1 proximal promoter, including an atypical cyclic AMP response element (position −57), an AP1 site (position −954), and GCrich sites (positions −110 and −143) (Altucci et al 1996;Sabbah et al 1999;Castro-Rivera et al 2001;Liu et al 2002;Park et al 2005). Stable integration of reporter constructs in BCC was recently used by Cicatiello et al (2004) to show that in this context estrogen stimulation required primarily the AP1 site. These authors proposed that ER␣ loading at the CCND1 promoter upon estrogen stimulation was mediated through interaction with AP1, resulting in the assembly of an activator complex responsible for CCND1 transcriptional induction.…”