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Author Guy Leclercq

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Natural Anti-Estrogen Receptor Alpha Antibodies Able to Induce Estrogenic Responses in Breast Cancer Cells: Hypotheses Concerning Their Mechanisms of Action and Emergence.

Guy Leclercq,

The detection of human anti-estrogen receptor α antibodies (ERαABs) inducing estrogenic responses in MCF-7 mammary tumor cells suggests their implication in breast cancer emergence and/or evolution. A recent report revealing a correlation between the titer of such antibodies in sera from patients suffering from this disease and the percentage of ... Read more >>

Int J Mol Sci (International journal of molecular sciences)
[2018, 19(2):]

Cited: 2 times

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ERE-dependent transcription and cell proliferation: Independency of these two processes mediated by the introduction of a sulfone function into the weak estrogen estrothiazine.

Yves Jacquot, Dany Spaggiari, Julie Schappler, Eric Lesniewska, Serge Rudaz, Guy Leclercq,

The synthetic coumestrol derivative 6,12-dihydro-3-methoxy-1-benzopyrano[3,4-b][1,4]benzothiazin-6-one (estrothiazine, ESTZ) has been identified as a weak estrogen receptor α (ERα) ligand unable to compete with tritiated estradiol. The biological activity of this compound, supported by a methoxy group in position 3, seems mainly to result from its capacity to activate ERα dimerization without ... Read more >>

Eur J Pharm Sci (European journal of pharmaceutical sciences : official journal of the European Federation for Pharmaceutical Sciences)
[2017, 109:169-181]

Cited: 2 times

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ERα dimerization: a key factor for the weak estrogenic activity of an ERα modulator unable to compete with estradiol in binding assays.

Guy Leclercq, Ioanna Laïos, Céline Elie-Caille, Denis Leiber, Guy Laurent, Eric Lesniewska, Zahra Tanfin, Yves Jacquot,

Estrothiazine (ESTZ) is a weak estrogen sharing structural similarities with coumestrol. ESTZ failed to compete with [3H]17β-estradiol ([3H]17β-E2) for binding to the estrogen receptor α (ERα), questioning its ability to interact with the receptor. However, detection by atomic force spectroscopy (AFS) of an ESTZ-induced ERα dimerization has eliminated any remaining ... Read more >>

J. Recept. Signal Transduct. Res. (Journal of receptor and signal transduction research)
[2017, 37(2):149-166]

Cited: 1 time

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The sequence Pro295-Thr311 of the hinge region of oestrogen receptor α is involved in ERK1/2 activation via GPR30 in leiomyoma cells.

Denis Leiber, Fabienne Burlina, Cillian Byrne, Philippe Robin, Christophe Piesse, Lucie Gonzalez, Guy Leclercq, Zahra Tanfin, Yves Jacquot,

The ERα (oestrogen receptor α)-derived peptide ERα17p activates rapid signalling events in breast carcinoma cells under steroid-deprived conditions. In the present study, we investigated its effects in ELT3 leiomyoma cells under similar conditions. We show that it activates ERK1/2 (extracellular-signal-regulated kinase 1/2), the Gαi protein, the trans-activation of EGFR (epidermal ... Read more >>

Biochem. J. (The Biochemical journal)
[2015, 472(1):97-109]

Cited: 6 times

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Whole transcriptome analysis of the ERα synthetic fragment P295-T311 (ERα17p) identifies specific ERα-isoform (ERα, ERα36)-dependent and -independent actions in breast cancer cells.

George Notas, Marilena Kampa, Vassiliki Pelekanou, Maria Troullinaki, Yves Jacquot, Guy Leclercq, Elias Castanas,

ERα17p is a peptide corresponding to the sequence P295LMIKRSKKNSLALSLT311 of the estrogen receptor alpha (ERα) and initially found to interfere with ERα-related calmodulin binding. ERα17p was subsequently found to elicit estrogenic responses in E2-deprived ERα-positive breast cancer cells, increasing proliferation and ERE-dependent gene transcription. Surprisingly, in E2-supplemented media, ERα17p-induced apoptosis ... Read more >>

Mol Oncol (Molecular oncology)
[2013, 7(3):595-610]

Cited: 6 times

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Interactions of isoflavones and other plant derived estrogens with estrogen receptors for prevention and treatment of breast cancer-considerations concerning related efficacy and safety.

Guy Leclercq, Yves Jacquot,

Phytoestrogens are natural endocrine disruptors that interfere with estrogenic pathways. They insert directly within the hormone-binding domain of ERα and β, with a preference for the β isoform of which the concentration predominates in the normal mammary epithelium. Since ERβ antagonizes the growth promoting effect of ERα, which is mainly ... Read more >>

J. Steroid Biochem. Mol. Biol. (The Journal of steroid biochemistry and molecular biology)
[2014, 139:237-244]

Cited: 18 times

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Electronic effects of 11β substituted 17β-estradiol derivatives and instrumental effects on the relative gas phase acidity.

Sandrine Bourgoin-Voillard, Françoise Fournier, Carlos Afonso, Emilie-Laure Zins, Yves Jacquot, Claude Pèpe, Guy Leclercq, Jean-Claude Tabet,

Numerous studies have highlighted the role of the proton donor characteristics of the phenol group of 17β-estradiol (E(2)) in its association with the estrogen receptor alpha (ERα). Since the substitutions at position C((11)) have been reported to modulate this association, we hypothesized that such substitutions may modify the phenol acidity. ... Read more >>

J. Am. Soc. Mass Spectrom. (Journal of the American Society for Mass Spectrometry)
[2012, 23(12):2167-2177]

Cited: 1 time

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Calcium-induced activation of estrogen receptor alpha--New insight.

Guy Leclercq,

Calcium being an important modulator in multiple regulatory processes, we overviewed reported investigations concerning its potential influence on ERα transcriptional activity in breast cancer cells. Three main activating mechanisms depending on either intra- or extracellular calcium are described. At physiological intracellular concentration (μM), Ca(++) activates calmodulin and promotes its association ... Read more >>

Steroids (Steroids)
[2012, 77(10):924-927]

Cited: 10 times

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Palmitoylation regulates 17β-estradiol-induced estrogen receptor-α degradation and transcriptional activity.

Piergiorgio La Rosa, Valeria Pesiri, Guy Leclercq, Maria Marino, Filippo Acconcia,

The estrogen receptor-α (ERα) is a transcription factor that regulates gene expression through the binding to its cognate hormone 17β-estradiol (E2). ERα transcriptional activity is regulated by E2-evoked 26S proteasome-mediated ERα degradation and ERα serine (S) residue 118 phosphorylation. Furthermore, ERα mediates fast cell responses to E2 through the activation ... Read more >>

Mol. Endocrinol. (Molecular endocrinology (Baltimore, Md.))
[2012, 26(5):762-774]

Cited: 57 times

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ERα17p, a peptide reproducing the hinge region of the estrogen receptor α associates to biological membranes: A biophysical approach.

Cillian Byrne, Lucie Khemtémourian, Vassiliki Pelekanou, Marilena Kampa, Guy Leclercq, Sandrine Sagan, Elias Castanas, Fabienne Burlina, Yves Jacquot,

Recently, we identified a peptide (ERα17p, P(295)LMIKRSKKNSLALSLT(311)) that corresponds to the 295-311 sequence of the estrogen receptor α (ERα, hinge region) and which exerts a panel of pharmacological effects in breast cancer cells. Remarkably, these effects can result from the interaction of ERα17p with the plasma membrane. Herein, we show ... Read more >>

Steroids (Steroids)
[2012, 77(10):979-987]

Cited: 7 times

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ERα36, a new variant of the ERα is expressed in triple negative breast carcinomas and has a specific transcriptomic signature in breast cancer cell lines.

Vassiliki Pelekanou, George Notas, Marilena Kampa, Eleftheria Tsentelierou, Jelena Radojicic, Guy Leclercq, Elias Castanas, Efstathios N Stathopoulos,

Triple negative breast cancer is deprived of estrogen receptor alpha (ERα), progesterone receptor (PR) and HER-2 protein. It constitutes the most heterogeneous and aggressive group of breast carcinomas, for which identification of novel characteristics and characterization of putative targets becomes very demanding. In the present work we have assayed the ... Read more >>

Steroids (Steroids)
[2012, 77(10):928-934]

Cited: 18 times

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Biophysical studies of the interaction between calmodulin and the R²⁸⁷-T³¹¹ region of human estrogen receptor α reveals an atypical binding process.

Ludovic Carlier, Cillian Byrne, Emeric Miclet, Sandrine Bourgoin-Voillard, Magali Nicaise, Jean-Claude Tabet, Michel Desmadril, Guy Leclercq, Olivier Lequin, Yves Jacquot,

The transcriptional activity of human estrogen receptor ERα is modulated by a number of coregulatory proteins among which calmodulin (CaM). Segment 295-311 in the hinge region of ERα has previously been proposed to be the CaM binding site. In this work, we investigate the molecular mechanism of the interaction of ... Read more >>

Biochem. Biophys. Res. Commun. (Biochemical and biophysical research communications)
[2012, 419(2):356-361]

Cited: 6 times

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ERα17p, an ERα P295 -T311 fragment, modifies the migration of breast cancer cells, through actin cytoskeleton rearrangements.

Marilena Kampa, Vassiliki Pelekanou, Dominique Gallo, George Notas, Maria Troullinaki, Iosif Pediaditakis, Ioannis Charalampopoulos, Yves Jacquot, Guy Leclercq, Elias Castanas,

Recently, our knowledge on estrogen receptor alpha (ERα) functions and fate has progressed: ERα enters in repeated transcription-modulating cycles (nucleus/cytoplasm/membrane trafficking processes and proteasomal degradation) that are governed by specific protein-protein interactions. Receptor fragments, especially those resulting from the proteolysis of its ligand binding domain, as well as corresponding synthetic ... Read more >>

J. Cell. Biochem. (Journal of cellular biochemistry)
[2011, 112(12):3786-3796]

Cited: 6 times

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Peptides targeting estrogen receptor alpha-potential applications for breast cancer treatment.

Guy Leclercq, Dominique Gallo, Janine Cossy, Ioanna Laïos, Denis Larsimont, Guy Laurent, Yves Jacquot,

Activation of the estrogen receptor alpha (ERα) is of prime importance for the development of hormone-dependent breast cancers. Hence, drugs able to impede the emergence of an active folding of ERα have been used for a long time as a first line therapeutic strategy. Aromatase inhibitors that block estradiol synthesis ... Read more >>

Curr. Pharm. Des. (Current pharmaceutical design)
[2011, 17(25):2632-2653]

Cited: 7 times

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Lack of sufficient information on the specificity and selectivity of commercial phytoestrogens preparations for therapeutic purposes.

Guy Leclercq, Patricia de Cremoux, Pascale This, Yves Jacquot,

Phytoestrogens (PEs) are polyphenols of plant origin among which flavones, flavanones, isoflavones, coumarins, chalcones, lignans and stilbenes are the best representatives. By interacting with specific residues of the estradiol-binding pocket of estrogen receptors (ERs), they induce estrogenic responses, supporting the concept that they could be of benefits against the menopausal ... Read more >>

Maturitas (Maturitas)
[2011, 68(1):56-64]

Cited: 11 times

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A critical view of the effects of phytoestrogens on hot flashes and breast cancer risk.

Pascale This, Patricia de Cremoux, Guy Leclercq, Yves Jacquot,

The increased risk of breast cancer recently observed with some specific estro-progestin associations has raised concerns about the harmful effects of menopausal hormone replacement therapy (HRT). It has been proposed that phytoestrogens (PEs), which have a similar chemical structure to estrogens, could be used as HRT. The main selling points ... Read more >>

Maturitas (Maturitas)
[2011, 70(3):222-226]

Cited: 14 times

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Controversies concerning the use of phytoestrogens in menopause management: bioavailability and metabolism.

Patricia de Cremoux, Pascale This, Guy Leclercq, Yves Jacquot,

It has been proposed that the use of phytoestrogens (PE) in menopausal therapy could be beneficial to woman health, particularly with respect to hot flushes. Indeed, PE may compensate the lack of endogenous 17beta-estradiol occurring during menopause. However, therapeutic benefits remain questionable, as highlighted by recent publications. Indeed, data are ... Read more >>

Maturitas (Maturitas)
[2010, 65(4):334-339]

Cited: 18 times

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Recent insights into the effect of natural and environmental estrogens on mammary development and carcinogenesis.

Vassiliki Pelekanou, Guy Leclercq,

The present work reviews recent findings related to the action of steroidal (physiological) estrogens on normal mammary gland development and carcinogenesis, as well as effects of related environmental mediators (phyto- and xeno-estrogens), the role of which remains controversial. Orchestration by estrogen receptors (i.e. ERα and ERβ) and coregulators of growth, ... Read more >>

Int. J. Dev. Biol. (The International journal of developmental biology)
[2011, 55(7-9):869-878]

Cited: 19 times

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The estrogen receptor alpha-derived peptide ERα17p (P(295)-T(311)) exerts pro-apoptotic actions in breast cancer cells in vitro and in vivo, independently from their ERα status.

Vassiliki Pelekanou, Marilena Kampa, Dominique Gallo, George Notas, Maria Troullinaki, Hugues Duvillier, Yves Jacquot, Efstathios N Stathopoulos, Elias Castanas, Guy Leclercq,

In recent years, our knowledge on estrogen receptors (ER) has been modified profoundly with the identification and the deciphering of the role of its protein effectors, as well as with the deeper insight of its molecular structure/function dynamics, characteristics associated with its nucleo-cytoplasmic-membrane shuttling properties. Also, significant progress has been made ... Read more >>

Mol Oncol (Molecular oncology)
[2011, 5(1):36-47]

Cited: 9 times

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Stereochemical effects during [M-H]- dissociations of epimeric 11-OH-17beta-estradiols and distant electronic effects of substituents at C(11) position on gas phase acidity.

Sandrine Bourgoin-Voillard, Emilie-Laure Zins, Françoise Fournier, Yves Jacquot, Carlos Afonso, Claude Pèpe, Guy Leclercq, Jean-Claude Tabet,

The affinity of estradiol derivatives for the estrogen receptor (ER) depends strongly on nature and stereochemistry of substituents in C(11) position of the 17beta-estradiol (I). In this work, the stereochemistry effects of the 11alpha-OH-17beta-estradiol (III(alpha)) and 11beta-OH-17beta-estradiol (III(beta)) were investigated using CID experiments and gas-phase acidity (DeltaH degrees (acid)) determination. ... Read more >>

J. Am. Soc. Mass Spectrom. (Journal of the American Society for Mass Spectrometry)
[2009, 20(12):2318-2333]

Cited: 7 times

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A ferrocenyl derivative of hydroxytamoxifen elicits an estrogen receptor-independent mechanism of action in breast cancer cell lines.

Anne Vessières, Cyril Corbet, Jan Martin Heldt, Nicolas Lories, Nathalie Jouy, Ioanna Laïos, Guy Leclercq, Gérard Jaouen, Robert-Alain Toillon,

The aim of this work was to investigate the mechanism of action of ferrocifen (Fc-OH-TAM), the ferrocenyl analog of 4-hydroxy-tamoxifen (OH-TAM), which is the active metabolite of tamoxifen, the drug most widely prescribed for treatment of hormone-dependent breast cancers. Fc-OH-TAM showed an anti-proliferative effect on the six breast cancer cell ... Read more >>

J. Inorg. Biochem. (Journal of inorganic biochemistry)
[2010, 104(5):503-511]

Cited: 23 times

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Identification of a human estrogen receptor alpha-derived antiestrogenic peptide that adopts a polyproline II conformation.

Josef Kapitán, Dominique Gallo, Nicole Goasdoué, Magali Nicaise, Michel Desmadril, Lutz Hecht, Guy Leclercq, Laurence D Barron, Yves Jacquot,

Polyproline II (PPII) helix is an extended secondary structure present in a number of proteins. PPII-containing sequences mediate specific protein-protein interactions with partners containing appropriate cognate domains called PPII-recognizing domains (PRDs) and are involved in the activation of intracellular signaling pathways. Thus, the identification of PPII structures in proteins is ... Read more >>

J. Pept. Sci. (Journal of peptide science : an official publication of the European Peptide Society)
[2009, 15(7):455-464]

Cited: 3 times

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Capacity of type I and II ligands to confer to estrogen receptor alpha an appropriate conformation for the recruitment of coactivators containing a LxxLL motif-Relationship with the regulation of receptor level and ERE-dependent transcription in MCF-7 cells.

Sandrine Bourgoin-Voillard, Dominique Gallo, Ioanna Laïos, Anny Cleeren, Latifa El Bali, Yves Jacquot, Denis Nonclercq, Guy Laurent, Jean-Claude Tabet, Guy Leclercq,

Estrogen receptor alpha (ERalpha) belongs to the superfamily of nuclear receptors and as such acts as a ligand-modulated transcription factor. Ligands elicit in ERalpha conformational changes leading to the recruitment of coactivators required for the transactivation of target genes via cognate response elements. In many cells, activated ERalpha also undergoes ... Read more >>

Biochem Pharmacol (Biochemical pharmacology)
[2010, 79(5):746-757]

Cited: 13 times

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Effect of fluorination on the pharmacological profile of 11beta isomers of fulvestrant in breast carcinoma cells.

Vangelis Agouridas, Emmanuel Magnier, Jean-Claude Blazejewski, Ioanna Laïos, Anny Cleeren, Denis Nonclercq, Guy Laurent, Guy Leclercq,

We describe the synthesis of an 11beta isomer 3 of the steroidal antiestrogen fulvestrant 2. Partial fluorination of the 11beta side chain in 3 leads to 4, which still shows strong antiproliferative activity on MCF-7 cells. However, unlike 2 and 3, compound 4 fails to down-regulate estrogen receptor alpha (ERalpha). ... Read more >>

J Med Chem (Journal of medicinal chemistry)
[2009, 52(3):883-887]

Cited: 3 times

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Calmodulin, a regulatory partner of the estrogen receptor alpha in breast cancer cells.

Dominique Gallo, Yves Jacquot, Guy Laurent, Guy Leclercq,

Although calmodulin (CaM) interaction with estrogen receptor alpha (ERalpha) has been known for more than two decades, it is only recently that the molecular mechanism of CaM-mediated regulation of ERalpha is beginning to emerge. Others and we have identified a putative calmodulin binding site (P(295)LMIKRSKKNSLALSTADQMVS(317)) in ERalpha, at the boundary ... Read more >>

Mol. Cell. Endocrinol. (Molecular and cellular endocrinology)
[2008, 291(1-2):20-26]

Cited: 18 times

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