17β-Estradiol and tamoxifen stimulate rapid and transient ERK activation in MCF-7 cells via distinct signaling mechanisms

Visram, Hasina; Greer, Peter A.

doi:10.4161/cbt.5.12.3378

Cited by 12 publications

(7 citation statements)

References 40 publications

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“…The βγ-subunit activates the tyrosine kinase Src. Subsequently, EGF-receptor is autophosphorylated at tyrosine 1173 initiating the ras-MAP-kinase signaling, finally inducing proliferation of estrogen-stimulated cells independent of ERα [8, 9]. Most experiments elucidating the signaling pathways of GPR30 were performed with the breast cancer cell line SK-Br3 lacking expression of ERα and ERβ.…”

Section: Discussionmentioning

confidence: 99%

“…Adenylate cyclase activity was increased in MCF-7 breast cancer cells by 17β-estradiol within minutes leading to an activation of protein kinase A [7]. An activation of the MAP-kinase extracellular signal-regulated kinase (Erk) was also observed after short time stimulation of MCF-7 breast cancer cells with 17β-estradiol [8, 9]. It was assumed that an estrogen receptor resides at the plasma membrane [10].…”

Section: Introductionmentioning

confidence: 99%

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Inactivation of GPR30 reduces growth of triple-negative breast cancer cells: possible application in targeted therapy

Girgert

Emons

Gründker

2012

Breast Cancer Res Treat

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Triple-negative breast cancers lack estrogen receptor α (ERα), progesterone receptor, and do not overexpress human epidermal growth factor receptor 2 (Her-2). They are neither susceptible to endocrine therapy nor to a therapy using the anti-Her-2 antibody, trastuzumab. Therefore, an efficient targeted therapy is warranted. Triple-negative breast tumors frequently express membrane bound estrogen receptor G-protein coupled receptor (GPR30). As proof of principle, we analyzed the consequences of a knock-down of GPR30 expression on the growth regulation of triple-negative breast cancer cell lines. Cells of triple-negative breast cancer cell lines were transfected with siRNA against GPR30 or control siRNA, and cell growth was stimulated either with 10−9 M 17β-estradiol or 10−6 M 4-hydroxytamoxifen. Cell proliferation was measured using Alamar blue staining. Activation of c-Src and epidermal growth factor (EGF)-receptor was assessed using western blot. Expression of c-fos was quantified by reverse transcription polymerase chain reaction. Seven days after transfection with siRNA, GPR30 mRNA in triple-negative breast cancer cell lines MDA-MB-435 and HCC1806 was reduced by 74 and 90%, respectively. 10−8 M 17β-estradiol enhanced proliferation of MDA-MB-435 to 129.6 ± 5.4% of control (p < 0.05) and HCC1806 to 156.9 ± 15.4% of control (p < 0.05), respectively. 10−6 M 4-hydroxytamoxifen increased cell number of MDA-MB-435 to 121.0 ± 6.9% of control (p < 0.05) and HCC1806 to 124.5 ± 12.1% of control (n.s.), respectively. This increased proliferation by the two estrogenic compounds was completely prevented by knock-down of GPR30 expression in both cell lines. In control cells, activity of Src kinase was increased 3-fold by estradiol and 3.8-fold using 4-hydroxytamoxifen. Transactivation of the EGF-receptor was similarly increased in both cell lines by 17β-estradiol and 4-hydroxytamoxifen. Both compounds increased c-fos expression 1.5- and 3.1-fold, respectively. Knock-down of GPR30 expression completely abolished activation of all these signaling pathways responsible for enhanced proliferation. A pharmacological inhibition of GPR30 by specific small molecular inhibitors might prove to be an appropriate targeted therapy of triple-negative breast cancer in the future.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Inactivation of GPR30 reduces growth of triple-negative breast cancer cells: possible application in targeted therapy

Girgert

Emons

Gründker

2012

Breast Cancer Res Treat

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“…In addition to their genomic effects, selective ER modulators may also exert non-genomic effects on target cells; for example, tamoxifen has been demonstrated to induce activation of mitogen-activated protein kinase (MAPK) [ 7 ], focal adhesion kinase (FAK) [ 8 ] and Src [ 8 , 9 ], signalling elements frequently linked to tumour migration and invasion [ 10 , 11 ]. Interestingly, Src kinase is also implicated in limiting the response of tamoxifen, where it stimulates the weak AF-1 function of the tamoxifen-ER complex through its tyrosine kinase activity [ 12 ].…”

Section: Introductionmentioning

confidence: 99%

Anti-oestrogens but not oestrogen deprivation promote cellular invasion in intercellular adhesion-deficient breast cancer cells

et al. 2008

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Introduction Anti-oestrogens have been the mainstay of therapy in patients with oestrogen-receptor (ER) positive breast cancer and have provided significant improvements in survival. However, their benefits are limited by tumour recurrence in a significant proportion of initially drug-responsive breast cancer patients because of acquired anti-oestrogen resistance. Relapse on such therapies clinically presents as local and/or regional recurrences, frequently with distant metastases, and the prognosis for these patients is poor. The selective ER modulator, tamoxifen, classically exerts gene inhibitory effects during the drug-responsive phase in ER-positive breast cancer cells. Paradoxically, this drug is also able to induce the expression of genes, which in the appropriate cell context may contribute to an adverse cell phenotype. Here we have investigated the effects of tamoxifen and fulvestrant treatment on invasive signalling and compared this with the direct effects of oestrogen withdrawal to mimic the action of aromatase inhibitors. Methods The effect of oestrogen and 4-hydroxy-tamoxifen on the invasive capacity of endocrine-sensitive MCF-7 cells, in the presence or absence of functional E-cadherin, was determined by Matrigel invasion assays. Studies also monitored the impact of oestrogen withdrawal or treatment with fulvestrant on cell invasion. Western blotting using phospho-specific antibodies was performed to ascertain changes in invasive signalling in response to the two anti-oestrogens versus both oestradiol treatment and withdrawal. Results To the best of our knowledge, we report for the first time that tamoxifen can promote an invasive phenotype in ER-positive breast cancer cells under conditions of poor cell-cell contact and suggest a role for Src kinase and associated pro-invasive genes in this process. Our studies revealed that although this adverse effect is also apparent for further classes of anti-oestrogens, exemplified by the steroidal agent fulvestrant, it is absent during oestrogen withdrawal. Conclusions These data highlight a previously unreported effect of tamoxifen (and potentially further anti-oestrogens), that such agents appear able to induce breast cancer cell invasion in a specific context (absence of good cell-cell contacts), where these findings may have major clinical implications for those patients with tumours that have inherently poor intercellular adhesion. In such patients oestrogen deprivation with aromatase inhibitors may be more appropriate.

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“…Such effects of estrogens may be transduced by ER␣/␤ or other means of transduction via the ER-related receptor (3), but rapid effects of estrogen have also been proposed through action on the cell membrane involving G protein-coupled membrane protein receptor 30 (GPR30) (4) or some other mechanism (5). Significant evidence has accumulated to show that rapid effects of estrogens occur in a variety of cell types including breast cancer cell lines (6,7), endothelial cell lines (8,9), pituitary cell lines (10), and many other cells such as adipocytes (11). Thus, the concept that estrogens have rapid effects on cellular activity unexplained by genomic mechanisms has gained support (10).…”

mentioning

confidence: 98%

Rapid in Vivo Effects of Estradiol-17β in Ovine Pituitary Gonadotropes Are Displayed by Phosphorylation of Extracellularly Regulated Kinase, Serine/Threonine Kinase, and 3′,5′-Cyclic Adenosine 5′-Monophosphate-Responsive Element-Binding Protein

2007

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We have determined the time course of phosphorylation of MAPK/ERK, cAMP-responsive element-binding protein (CREB), and serine/threonine kinase (Akt) in ovine pituitary gonadotropes after in vivo injection (iv) of either 25 mug estradiol-17beta (E17beta) or vehicle. In ovariectomized ewes, E17beta increased the number of gonadotropes expressing phosphorylated (p)ERK-1/2 and pCREB immunoreactivity (-IR) within 90 min, as assessed by immunohistochemistry. By Western blot, we also showed that pERK-1/2, pCREB, and pAkt (ser 473) proteins were up-regulated by E17beta. In ovariectomized, hypothalamo-pituitary-disconnected animals, gonadotrope function was restored with hourly GnRH pulses (iv), and E17beta injection (iv) reduced LH response within 1 h. Immunohistochemistry showed that E17beta increased pERK-1/2-IR in gonadotropes within 15 min and peak response at 60 min. The number of cells immunoreactive for pCREB was greater in E17beta-treated animals than in vehicle-injected controls at 60 and 90 min. Western blot revealed a pERK-1/2 response within 15 min and pCREB response at 30 min. Up-regulation of pAkt occurred within 60 min of E17beta treatment. Thus, rapid effects of E17beta on gonadotropes involve phosphorylation of second messenger proteins with a time course that may relate to the rapid negative feedback effect to reduce responsiveness to GnRH.

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17β-Estradiol and tamoxifen stimulate rapid and transient ERK activation in MCF-7 cells via distinct signaling mechanisms

Cited by 12 publications

References 40 publications

Inactivation of GPR30 reduces growth of triple-negative breast cancer cells: possible application in targeted therapy

Inactivation of GPR30 reduces growth of triple-negative breast cancer cells: possible application in targeted therapy

Anti-oestrogens but not oestrogen deprivation promote cellular invasion in intercellular adhesion-deficient breast cancer cells

Rapid in Vivo Effects of Estradiol-17β in Ovine Pituitary Gonadotropes Are Displayed by Phosphorylation of Extracellularly Regulated Kinase, Serine/Threonine Kinase, and 3′,5′-Cyclic Adenosine 5′-Monophosphate-Responsive Element-Binding Protein

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