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Title: Modulation of RIZ gene expression is associated to estradiol control of MCF-7 breast cancer cell proliferation

Abstract

The retinoblastoma protein-interacting zinc-finger (RIZ) gene, a member of the nuclear protein methyltransferase superfamily, is characterized by the presence of the N-terminal PR domain. The RIZ gene encodes for two proteins, RIZ1 and RIZ2. While RIZ1 contains the PR (PRDI-BF1 and RIZ homologous) domain, RIZ2 lacks it. RIZ gene expression is altered in a variety of human cancers and RIZ1 is now considered to be a candidate tumor suppressor. Estradiol treatment of MCF-7 cells produced a selective decrease of RIZ1 transcript and an increase of total RIZ mRNA. Experiments of chromatin immunoprecipitation indicated that RIZ2 protein expression was controlled by estrogen receptor and RIZ1 had a direct repressor function on c-myc gene expression. To investigate the role of RIZ gene products as regulators of the proliferation/differentiation transition, we analyzed the effects of forced suppression of RIZ1 induced in MCF-7 cells by siRNA of the PR domain-containing form. Silencing of RIZ1 expression stimulated cell proliferation, similar to the effect of estradiol on these cells, associated with a transient increase of c-myc expression.

Authors:
 [1];  [2];  [2];  [2];  [2];  [2];  [2]
  1. Dipartimento di Patologia generale, Seconda Universita degli studi di Napoli, Via Luigi de Crecchio 7, I-80138 Naples (Italy). E-mail: moncharmont@unimol.it
  2. Dipartimento di Patologia generale, Seconda Universita degli studi di Napoli, Via Luigi de Crecchio 7, I-80138 Naples (Italy)
Publication Date:
OSTI Identifier:
20775336
Resource Type:
Journal Article
Resource Relation:
Journal Name: Experimental Cell Research; Journal Volume: 312; Journal Issue: 3; Other Information: DOI: 10.1016/j.yexcr.2005.11.002; PII: S0014-4827(05)00523-9; Copyright (c) 2005 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
60 APPLIED LIFE SCIENCES; CELL PROLIFERATION; CHROMATIN; ESTRADIOL; GENE REGULATION; GENES; INHIBITION; MAMMARY GLANDS; MODULATION; NEOPLASMS; RECEPTORS; ZINC

Citation Formats

Gazzerro, Patrizia, Abbondanza, Ciro, D'Arcangelo, Andrea, Rossi, Mariangela, Medici, Nicola, Moncharmont, Bruno, and Puca, Giovanni Alfredo. Modulation of RIZ gene expression is associated to estradiol control of MCF-7 breast cancer cell proliferation. United States: N. p., 2006. Web. doi:10.1016/j.yexcr.2005.11.002.
Gazzerro, Patrizia, Abbondanza, Ciro, D'Arcangelo, Andrea, Rossi, Mariangela, Medici, Nicola, Moncharmont, Bruno, & Puca, Giovanni Alfredo. Modulation of RIZ gene expression is associated to estradiol control of MCF-7 breast cancer cell proliferation. United States. doi:10.1016/j.yexcr.2005.11.002.
Gazzerro, Patrizia, Abbondanza, Ciro, D'Arcangelo, Andrea, Rossi, Mariangela, Medici, Nicola, Moncharmont, Bruno, and Puca, Giovanni Alfredo. Wed . "Modulation of RIZ gene expression is associated to estradiol control of MCF-7 breast cancer cell proliferation". United States. doi:10.1016/j.yexcr.2005.11.002.
@article{osti_20775336,
title = {Modulation of RIZ gene expression is associated to estradiol control of MCF-7 breast cancer cell proliferation},
author = {Gazzerro, Patrizia and Abbondanza, Ciro and D'Arcangelo, Andrea and Rossi, Mariangela and Medici, Nicola and Moncharmont, Bruno and Puca, Giovanni Alfredo},
abstractNote = {The retinoblastoma protein-interacting zinc-finger (RIZ) gene, a member of the nuclear protein methyltransferase superfamily, is characterized by the presence of the N-terminal PR domain. The RIZ gene encodes for two proteins, RIZ1 and RIZ2. While RIZ1 contains the PR (PRDI-BF1 and RIZ homologous) domain, RIZ2 lacks it. RIZ gene expression is altered in a variety of human cancers and RIZ1 is now considered to be a candidate tumor suppressor. Estradiol treatment of MCF-7 cells produced a selective decrease of RIZ1 transcript and an increase of total RIZ mRNA. Experiments of chromatin immunoprecipitation indicated that RIZ2 protein expression was controlled by estrogen receptor and RIZ1 had a direct repressor function on c-myc gene expression. To investigate the role of RIZ gene products as regulators of the proliferation/differentiation transition, we analyzed the effects of forced suppression of RIZ1 induced in MCF-7 cells by siRNA of the PR domain-containing form. Silencing of RIZ1 expression stimulated cell proliferation, similar to the effect of estradiol on these cells, associated with a transient increase of c-myc expression.},
doi = {10.1016/j.yexcr.2005.11.002},
journal = {Experimental Cell Research},
number = 3,
volume = 312,
place = {United States},
year = {Wed Feb 01 00:00:00 EST 2006},
month = {Wed Feb 01 00:00:00 EST 2006}
}
  • The responsiveness of the human mammary carcinoma cell line MCF-7 to estradiol and tamoxifen treatment has been studied in different culture conditions. Cells from exponentially growing cultures were compared with cells in their initial cycles after replating from confluent cultures (''confluent-log'' cells). It has been observed that estradiol stimulation of tritiated thymidine incorporation decreases with cell density and that ''confluent-log'' cells are estrogen unresponsive for a period of four cell cycles in serum-free medium conditions. On the other hand, growth of cells replated from exponentially growing, as well as from confluent cultures, can be inhibited by tamoxifen or a combinedmore » treatment with tamoxifen and the progestin levonorgestrel. This growth inhibitory effect can be rescued by estradiol when cells are replated from exponentially growing cultures. The growth inhibitory effect cannot be rescued by estradiol alone (10(-10) to 10(-8) M) when cells are replated from confluent cultures. In this condition, the addition of steroid depleted serum is necessary to reverse the state of estradiol unresponsiveness. Serum can be replaced by high density lipoproteins but not by low density lipoproteins or lipoprotein deficient serum. The present data show that estradiol and HDL interact in the control of MCF-7 cell proliferation.« less
  • Ponicidin and oridonin are novel diterpenoids isolated from Rabdosia rubescens. We tested their effects in MCF-7 and MDA-MB-231 cells, as representing low and high invasive breast carcinoma, with normal MCF-10A cells. Clonogenicity and proliferation in MCF-7 cells were inhibited more significantly by ponicidin than oridonin, while the reverse was observed in MCF-10A cells. Ponicidin and oridonin induced S/G{sub 2}M arrest and G{sub 1}/S block in MCF-7 cells. In MCF-10A cells treated with either diterpenoid, induction of apoptosis was observed. Moreover, oridonin almost completely blocked MCF-10A progression from S to G{sub 2}/M phase; in contrast, ponicidin-treated MCF-10A cells showed no discernablemore » changes in cell cycle phase distribution. Neither diterpenoid affected growth of MDA-MB-231 cells, at the dose range effective for MCF-7 or MCF-10A cells. Ponicidin-treated MCF-7 cells expressed reduced levels of cyclin B1, cdc2, transcription factor E2F, and Rb including phosphorylation at S780. Less pronounced effects were found in cells treated with oridonin. Neither compound altered cyclin D1 and cdk4 in MCF-7 cells. In MCF-10A cells, oridonin was more active than ponicidin in inhibiting the expression of cyclin B1, cdc2, S780-phosphorylated Rb, and E2F. To further investigate induction of apoptosis in MCF-10A cells, we measured changes in NF-{kappa}B. Decreases in p65 or p50 forms of NF-{kappa}B and its upstream regulator I-{kappa}B were found in oridonin-treated MCF-10A and not MCF-7 cells. Taken together, these results provide a mechanistic framework for the cellular effects of ponicidin and oridonin in different stage breast cancer cells.« less
  • Highlights: Black-Right-Pointing-Pointer We examined the regulation and biological functions of B4GALT1 expression induced by estrogen. Black-Right-Pointing-Pointer Estrogen-induced B4GALT1 expression through the direct binding of ER-{alpha} to ERE in MCF-7 cells. Black-Right-Pointing-Pointer B4GALT1 expression activates the proliferation of MCF-7 cells via its receptor function. Black-Right-Pointing-Pointer Thus, we suggest B4GALT1 as a molecular target for inhibiting breast cancer proliferation. -- Abstract: Beta 1,4-galactosyltransferase 1 (B4GALT1) synthesizes galactose {beta}-1,4-N-acetylglucosamine (Gal{beta}1-4GlcNAc) groups on N-linked sugar chains of glycoproteins, which play important roles in many biological events, including the proliferation and migration of cancer cells. A previous microarray study reported that this gene is expressedmore » by estrogen treatment in breast cancer. In this study, we examined the regulatory mechanisms and biological functions of estrogen-induced B4GALT1 expression. Our data showed that estrogen-induced expression of B4GALT1 is localized in intracellular compartments and in the plasma membrane. In addition, B4GALT1 has an enzyme activity involved in the production of the Gal{beta}1-4GlcNAc structure. The result from a promoter assay and chromatin immunoprecipitation revealed that 3 different estrogen response elements (EREs) in the B4GALT1 promoter are critical for responsiveness to estrogen. In addition, the estrogen antagonists ICI 182,780 and ER-{alpha}-ERE binding blocker TPBM inhibit the expression of estrogen-induced B4GALT1. However, the inhibition of signal molecules relating to the extra-nuclear pathway, including the G-protein coupled receptors, Ras, and mitogen-activated protein kinases, had no inhibitory effects on B4GALT1 expression. The knock-down of the B4GALT1 gene and the inhibition of membrane B4GALT1 function resulted in the significant inhibition of estrogen-induced proliferation of MCF-7 cells. Considering these results, we propose that estrogen regulates the expression of B4GALT1 through the direct binding of ER-{alpha} to ERE and that the expressed B4GALT1 plays a crucial role in the proliferation of MCF-7 cells through its activity as a membrane receptor.« less
  • The cumulative exposure to estrogens is an important determinant in the risk of breast cancer, yet the full range of mechanisms involving estrogens in the genesis and progression of breast cancer remains a subject of debate. Interactions of estrogens and environmental toxicants have received attention as putative factors contributing to carcinogenesis. Mechanistic studies have demonstrated interactions between estrogen receptor alpha (ERalpha) and the aryl hydrocarbon receptor (AhR), with consequences on the genes that they regulate. Many studies of ERalpha and AhR-mediated effects and crosstalk between them have focused on the initial molecular events. In this study, we investigated ERalpha- andmore » AhR-mediated effects in long-term estrogen exposed (LTEE) MCF-7 human breast cancer cells, which were obtained by continuous culturing for at least 12 weeks in medium supplemented with 1 nM of 17beta-estradiol (E{sub 2}). With these LTEE cells and with parallel control cells cultured without E{sub 2} supplementation, we performed an extensive study of cytochrome P450 (CYP) induction, carcinogen bioactivation, global gene expression, and tumorigenicity in immunocompromised mice. We found that LTEE cells, in comparison with control cells, had higher levels of AhR mRNA and protein, greater responsiveness for AhR-regulated CYP1A1 and CYP1B1 induction, a 6-fold higher initial level of benzo(a)pyrene-DNA adducts as determined by liquid chromatography tandem mass spectrometry, marked differences in the expression of numerous genes, and a higher rate of E{sub 2}-dependent tumor growth as xenografts. These studies indicate that LTEE causes adaptive responses in MCF-7 cells, which may reflect processes that contribute to the overall carcinogenic effect of E{sub 2}.« less
  • Since over 60% of breast cancers are estrogen receptor positive (ER+), many therapies have targeted the ER. The ER is activated by both estrogen binding and phosphorylation. While anti-estrogen therapies, such as tamoxifen (Tam) have been successful they do not target the growth factor promoting phosphorylation of the ER. Other proliferation pathways such as the phosphatidylinositol-3 kinase, (PI3K) and the mitogen-activated protein kinase (MAPK) pathways are activated in breast cancer cells and are associated with poor prognosis. Thus targeting multiple cellular proliferation and survival pathways at the onset of treatment is critical for the development of more effective therapies. Themore » grapefruit flavanone naringenin (Nar) is an inhibitor of both the PI3K and MAPK pathways. Previous studies examining either Nar or Tam used charcoal-stripped serum which removed estrogen as well as other factors. We wanted to use serum containing medium in order to retain all the potential inducers of cell proliferation so as not to exclude any targets of Nar. Here we show that a Nar–Tam combination is more effective than either Tam alone or Nar alone in MCF-7 breast cancer cells. We demonstrate that a Nar–Tam combination impaired cellular proliferation and viability to a greater extent than either component alone in MCF-7 cells. Furthermore, the use of a Nar–Tam combination requires lower concentrations of both compounds to achieve the same effects on proliferation and viability. Nar may function by inhibiting both PI3K and MAPK pathways as well as localizing ERα to the cytoplasm in MCF-7 cells. Our results demonstrate that a Nar–Tam combination induces apoptosis and impairs proliferation signaling to a greater extent than either compound alone. These studies provide critical information for understanding the molecular mechanisms involved in cell proliferation and apoptosis in breast cancer cells. - Highlights: • Nar–Tam impairs cell viability more effectively than either compound alone. • Lower concentrations of Nar and Tam are required when used in combination. • Nar localizes ERα to a perinuclear region of the cell. • Nar reduces protein levels of ERK1/2 and AKT.« less