Prolonged treatment of breast cancer cells with antiestrogens increases the activating protein-1-mediated response: involvement of the estrogen receptor.

Astruc, M.; Chabret, Claude; Bali, Purva; Gagne, Didier; Pons, Michel

doi:10.1210/endo.136.3.7867590

Cited by 35 publications

(31 citation statements)

References 26 publications

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“…Activation of the activating protein-I (AP-1) mediated pathway by the ER-ligand complex has been reported as an alternative pathway for ER action in breast cancer cells after long-term tamoxifen treatment (Astruc et al, 1995) as well as in other cell lines (Gaub et al, 1990;Philips et al, 1993;Umayahara et al, 1994;Webb et al, 1995). It is possible that as a consequence of transfection of the ER into cells that were initially ER negative, the classical ER-mediated pathway is shifted towards the alternate pathway.…”

Section: Discussionmentioning

confidence: 99%

The oestrogen-like effect of 4-hydroxytamoxifen on induction of transforming growth factor alpha mRNA in MDA-MB-231 breast cancer cells stably expressing the oestrogen receptor

Levenson

Tonetti²,

Jordan³

1998

Br J Cancer

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Summary Oestrogens and antioestrogens modulate the synthesis of transforming growth factor alpha (TGF-a) in breast cancer cells. The purpose of the present report was to examine regulation of TGF-a gene expression by oestradiol (E2) and antioestrogens in MDA-MB-231 breast cancer cells transfected with either the wild-type or mutant oestrogen receptor (ER). We recently reported the concentrationdependent E2 stimulation of TGF-a mRNA in MDA-MB-231 ER transfectants (Levenson et al, 1997). We now report that 4-hydroxytamoxifen (4-OHT) shows oestrogen-like effects on the induction of TGF-a gene expression in our transfectants. Accumulation of TGF-a mRNA in response to both E2 and 4-OHT but not in response to the pure antioestrogen ICI 182,780 suggests that E2-ER and 4-OHT-ER complexes can bind to an oestrogen response element (ERE), located in the promoter region of the TGF-a gene and can activate transcription of the gene. Surprisingly, no activation of luciferase expression was observed after transient transfection of the TGF-a ERE/luciferase reporter constructs. Possible activation of an alternative ER-mediated pathway responsible for the regulation of TGF-a gene expression in the ER transfectants is discussed.

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Section: Discussionmentioning

confidence: 99%

The oestrogen-like effect of 4-hydroxytamoxifen on induction of transforming growth factor alpha mRNA in MDA-MB-231 breast cancer cells stably expressing the oestrogen receptor

Levenson

Tonetti²,

Jordan³

1998

Br J Cancer

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“…Briefly, to obtain MELN cells, ER␣-positive breast cancer MCF-7 cells were transfected with the estrogen-responsive gene EREbGlob-Luc-SV-Neo (31). To obtain MTLN cells, MCF-7 cells were co-transfected with the AP1-responsive gene TRE 3 -TkLuc and the neomycin resistance gene pSV2-Neo (32). Selection of resistant clones by Geneticin was performed at 1 mg/ml.…”

Section: Methodsmentioning

confidence: 99%

Estrogen Receptor α and the Activating Protein-1 Complex Cooperate during Insulin-like Growth Factor-I-induced Transcriptional Activation of the pS2/TFF1 Gene

Baron

Escande

Albérola

et al. 2007

Journal of Biological Chemistry

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Insulin like growth factor I (IGF-I) displays estrogenic activity in breast cancer cells. This activity is strictly dependent on the presence of estrogen receptor ␣ (ER␣). However the precise molecular mechanisms involved in this process are still unclear. IGF-I treatment induces phosphorylation of the AF1 domain of ER␣ and activation of estrogen regulated genes. These genes are characterized by important differences in promoter architecture and response element composition. We show that promoter structure is crucial for IGF-I-induced transcription activation. We demonstrate that on a complex promoter such as the pS2/TFF1 promoter, which contains binding sites for ER␣ and for the activating protein-1 (AP1) complex, transcriptional activation by IGF-I requires both ER␣ and the AP1 complex. IGF-I is unable to stimulate transcription of an estrogen-regulated gene under the control of a minimal promoter containing only a binding site for ER␣. We propose a molecular mechanism with stepwise assembly of the AP1 complex and ER␣ during transcription activation of pS2/TFF1 by IGF-I. IGF-I stimulation induces rapid phosphorylation and an increase in protein levels of the AP1 complex. Binding of the phosphorylated AP1 complex to the pS2/TFF1 promoter allows recruitment of the chromatin remodeling factor Brg1 followed by binding of ER␣ via its interaction with c-Jun.Control of breast cancer cell proliferation is a complex, multifactorial, and interactive process. Estradiol, a steroid hormone, which acts via its nuclear receptors (ER␣ 2 and -␤ for estrogen receptor ␣ and ␤) and growth factors such as insulinlike growth factor I (IGF-I) or IGF-II, epidermal growth factor, or transforming growth factor ␣, whose action is mediated by tyrosine kinase transmembrane receptors, controls gene expression and cellular proliferation of breast cancer cells (1). Although it was discovered more than 10 years ago that ER␣ could be activated in a ligand-independent fashion by growth factors like epidermal growth factor or IGF (2), the cross-talk between estrogens and growth factor pathways remains to be elucidated.In the classical model of ER action, the receptor binds as a homodimer (3) or a heterodimer (4 -7) to estrogen response elements (EREs) within the promoters of estrogen-responsive genes. Once present on the promoter of estrogen responsive genes, ER recruits an array of transcriptional cofactors (coactivators and corepressors) that bind to the receptor and interact with other transcription factors, including components of the general transcription machinery. Some of these cofactors possess chromatin-remodeling activities or histone modifying activities or recruit additional proteins to the complex to mediate transcription (for review, see Ref. 8). ER␣ may also modulate transcription without receptor-DNA interaction by functional interference with other transcription factors such as activating protein-1 (AP1) (for review, see Refs. 9 -12).The AP1 complex, which is implicated in diverse cellular processes, including differentiation, c...

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“…Twenty-four hours later, cells were incubated with the various tested compounds. After 8-h incubation, cells were treated as described previously for assaying the luciferase activity (Astruc et al, 1995). PMA was used as positive control.…”

Section: U373 Cells Proliferation Studies By [mentioning

confidence: 99%

C-Terminal Heptapeptide of Gastrin Inhibits Astrocytomas Motility by Interacting with a New Gastrin Binding Site

Pannequin¹,

Oiry²,

Morel³

et al. 2002

J Pharmacol Exp Ther

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It is well known that the amidated C-terminal part of gastrin is crucial for its interaction with the classical seven transmembrane domain receptors CCK-1 or CCK-2. Nevertheless, over the past 10 years, several groups have characterized new binding sites using peptides related to gastrin (particularly glycineextended forms of gastrin) on various tumoral and nontumoral cell lines. In the present study, we focused on the human astrocytic tumoral cell line U373. Although it has been described that gastrin was able to inhibit the motility of these cells, we were unable to detect any classical CCK/gastrin receptor.On the other hand, by using the radiolabeled C-terminal heptapeptide of gastrin ( 125

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Prolonged treatment of breast cancer cells with antiestrogens increases the activating protein-1-mediated response: involvement of the estrogen receptor.

Cited by 35 publications

References 26 publications

The oestrogen-like effect of 4-hydroxytamoxifen on induction of transforming growth factor alpha mRNA in MDA-MB-231 breast cancer cells stably expressing the oestrogen receptor

The oestrogen-like effect of 4-hydroxytamoxifen on induction of transforming growth factor alpha mRNA in MDA-MB-231 breast cancer cells stably expressing the oestrogen receptor

Estrogen Receptor α and the Activating Protein-1 Complex Cooperate during Insulin-like Growth Factor-I-induced Transcriptional Activation of the pS2/TFF1 Gene

C-Terminal Heptapeptide of Gastrin Inhibits Astrocytomas Motility by Interacting with a New Gastrin Binding Site

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