Publications by authors named "Frédéric Hague"

16 Publications

  • Page 1 of 1

Cadmium exposure enhances cell migration and invasion through modulated TRPM7 channel expression.

Arch Toxicol 2020 03 20;94(3):735-747. Epub 2020 Feb 20.

Laboratoire de Physiologie Cellulaire et Moléculaire - UR UPJV 4667, UFR Sciences, Université de Picardie Jules Verne (UPJV), 80039, Amiens, France.

Cadmium is a xenobiotic involved in neoplastic transformation. Cadmium enters the cells through divalent cation transporters including the Transient Receptor Potential Melastatin-related 7 (TRPM7) which is known to be involved in cancer cell fate. This work aimed to study the role of TRPM7 in neoplastic transformation induced by cadmium exposure in non-cancer epithelial cells. Non-cancer epithelial cells were chronically exposed to low-dose of cadmium. TRPM7 expression and function were studied by Western-Blot, Patch-Clamp and calcium and magnesium imaging. Finally, cell migration and invasion were studied by Boyden chamber assays. Chronic cadmium exposure induced TRPM7 overexpression and increased the membrane currents (P < 0.001). Cells exposed to cadmium had higher intracellular calcium and magnesium levels (P < 0.05). TRPM7 silencing restored calcium levels but strongly decreased intracellular magnesium concentration (P < 0.001). Moreover, cadmium exposure enhanced both cell migration and invasion, but TRPM7 silencing strongly decreased these features (P < 0.001). Furthermore, mammary epithelial cells exposed to cadmium became rounded and had less cell-to-cell junctions. Cadmium exposure decreased epithelial markers while the mesenchymal ones were increased. Importantly, TRPM7 silencing was able to reverse these phenotypic modifications (P < 0.05). To summarize, our data show that chronic cadmium exposure enhanced TRPM7 expression and activity in non-cancer epithelial cells. TRPM7 overexpression induced intracellular magnesium increase and stimulated cell migration and invasion. These neoplastic properties could be linked to a TRPM7-dependent epithelial-to-mesenchymal transition reprogramming in cell exposed to cadmium. These findings provide new insights into the regulation of cell fates by cadmium exposure.
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http://dx.doi.org/10.1007/s00204-020-02674-wDOI Listing
March 2020

Ion Channels: New Actors Playing in Chemotherapeutic Resistance.

Cancers (Basel) 2019 Mar 16;11(3). Epub 2019 Mar 16.

Laboratoire de Physiologie Cellulaire et Moléculaire (EA 4667), Université de Picardie Jules Verne, UFR des Sciences, 33 Rue St Leu, 80039 Amiens, France.

In the battle against cancer cells, therapeutic modalities are drastically limited by intrinsic or acquired drug resistance. Resistance to therapy is not only common, but expected: if systemic agents used for cancer treatment are usually active at the beginning of therapy (i.e., 90% of primary breast cancers and 50% of metastases), about 30% of patients with early-stage breast cancer will have recurrent disease. Altered expression of ion channels is now considered as one of the hallmarks of cancer, and several ion channels have been linked to cancer cell resistance. While ion channels have been associated with cell death, apoptosis and even chemoresistance since the late 80s, the molecular mechanisms linking ion channel expression and/or function with chemotherapy have mostly emerged in the last ten years. In this review, we will highlight the relationships between ion channels and resistance to chemotherapy, with a special emphasis on the underlying molecular mechanisms.
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http://dx.doi.org/10.3390/cancers11030376DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6468599PMC
March 2019

Tumour cell blebbing and extracellular vesicle shedding: key role of matrikines and ribosomal protein SA.

Br J Cancer 2019 02 11;120(4):453-465. Epub 2019 Feb 11.

Université de Reims Champagne Ardenne, SFR CAP-Santé (FED 4231), Laboratoire de Biochimie Médicale et Biologie Moléculaire, Reims, France.

Background: Carcinogenesis occurs in elastin-rich tissues and leads to local inflammation and elastolytic proteinase release. This contributes to bioactive matrix fragment (Matrikine) accumulation like elastin degradation products (EDP) stimulating tumour cell invasive and metastatic properties. We previously demonstrate that EDPs exert protumoural activities through Hsp90 secretion to stabilised extracellular proteinases.

Methods: EDP influence on cancer cell blebbing and extracellular vesicle shedding were examined with a videomicroscope coupled with confocal Yokogawa spinning disk, by transmission electron microscopy, scanning electron microscopy and confocal microscopy. The ribosomal protein SA (RPSA) elastin receptor was identified after affinity chromatography by western blotting and cell immunolocalisation. mRNA expression was studied using real-time PCR. SiRNA were used to confirm the essential role of RPSA.

Results: We demonstrate that extracellular matrix degradation products like EDPs induce tumour amoeboid phenotype with cell membrane blebbing and shedding of extracellular vesicle containing Hsp90 and proteinases in the extracellular space. EDPs influence intracellular calcium influx and cytoskeleton reorganisation. Among matrikines, VGVAPG and AGVPGLGVG peptides reproduced EDP effects through RPSA binding.

Conclusions: Our data suggests that matrikines induce cancer cell blebbing and extracellular vesicle release through RPSA binding, favouring dissemination, cell-to-cell communication and growth of cancer cells in metastatic sites.
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http://dx.doi.org/10.1038/s41416-019-0382-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6461924PMC
February 2019

Orai3 calcium channel and resistance to chemotherapy in breast cancer cells: the p53 connection.

Cell Death Differ 2018 03 11;25(4):693-707. Epub 2018 Jan 11.

Université de Picardie Jules Verne, UFR des Sciences, Laboratoire de Physiologie Cellulaire et Moléculaire (EA 4667), SFR CAP-SANTE (FED 4231), Amiens, France.

Orai proteins are highly selective calcium channels playing an important role in calcium entry. Orai3 channels are overexpressed in breast cancer (BC) tissues, and involved in their proliferation, cell cycle progression and survival. Herein, we sought to address the involvement of Orai3 in resistance to chemotherapeutic drugs. Using high-throughput approaches, we investigated major changes induced by Orai3 overexpression, including downstream signaling mechanisms involved in BC chemotherapy resistance. Resistance was dependent on external calcium presence and thus Orai3 functionality. This effect allowed a downregulation of the p53 tumor suppressor protein expression via the pro-survival PI3K/Sgk-1/Sek-1 pathway. We demonstrated that p53 degradation occurred not only via Mdm2, but also via another unexpected E3 ubiquitin ligase, Nedd4-2. We found supporting bioinformatic evidence linking Orai3 overexpression and chemoresistance in large human BC data sets. Altogether, our results shed light on the molecular mechanisms activated in BC cells commonly found to overexpress Orai3, allowing resistance to chemotherapeutic drugs.
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http://dx.doi.org/10.1038/s41418-017-0007-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5864197PMC
March 2018

Downregulation of type 3 inositol (1,4,5)-trisphosphate receptor decreases breast cancer cell migration through an oscillatory Ca signal.

Oncotarget 2017 Sep 18;8(42):72324-72341. Epub 2017 Aug 18.

Laboratory of Cellular and Molecular Physiology (EA-4667), "Ion Channels in Breast Cancer", SFR CAP-SANTE (FED-4231), University of Amiens, UFR Sciences, 80039 Amiens, France.

Breast cancer remains a research priority due to its invasive phenotype. Although the role of ion channels in cancer is now well established, the role of inositol (1,4,5)-trisphosphate (IP) receptors (IPRs) remains enigmatic. If the three IPRs subtypes expression have been identified in various cancers, little is known about their physiological role. Here, we investigated the involvement of IPR type 3 (IPR) in the migration processes of three human breast cancer cell lines showing different migration velocities: the low-migrating MCF-7 and the highly migrating and invasive MDA-MB-231 and MDA-MB-435S cell lines. We show that a higher IPR3 expression level, but not IPR1 nor IPR2, is correlated to a stronger cell line migration capacity and a sustained calcium signal. Interestingly, silencing of IPR3 highlights an oscillating calcium signaling profile and leads to a significant decrease of cell migration capacities of the three breast cancer cell lines. Conversely, stable overexpression of IPR3 in MCF-7 cells significantly increases their migration capacities. This effect is completely reversed by IPR3 silencing. In conclusion, we demonstrate that IPR3 expression level increases the migration capacity of human breast cancer cells by changing the calcium signature.
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http://dx.doi.org/10.18632/oncotarget.20327DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5641133PMC
September 2017

sp -Iminosugar α-glucosidase inhibitor 1-C-octyl-2-oxa-3-oxocastanospermine specifically affected breast cancer cell migration through Stim1, β1-integrin, and FAK signaling pathways.

J Cell Physiol 2017 Dec 25;232(12):3631-3640. Epub 2017 Apr 25.

Laboratory of Cellular and Molecular Physiology (EA 4667), SFR CAP-SANTE (FED 4132), UFR of Sciences, Amiens, France.

Aberrant glycosylation changes on many glycoproteins are often related to cancer progression and metastasis. sp -Iminosugar-type castanospermine analogues, inhibitors of α-glucosidases, have been reported to exhibit antitumor activity. However, their effects on cell migration and the underlying molecular mechanism are not fully understood. Here, we investigated the effect of the pseudo-C-octyl glycoside 2-oxa-3-oxocastanospermine derivatives (CO-OCS) on breast cancer cells (MCF-7 and MDA-MB-231 cells), and MCF-10A mammary normal cell lines. We showed that CO-OCS treatment results in the drastic decrease of breast cancer cell migration without affecting cell proliferation. Furthermore, CO-OCS significantly reduced both the expression of β1-integrin, which is a crucial interacting partner of Focal Adhesion Kinase (FAK), and the phosphorylation rates of FAK and ERK1/2. CO-OCS also drastically reduced Ca entry through Store Operated Channels (SOC). Orai1 and Stim1, two N-glycosylated proteins, are involved in Store-Operated Calcium Entry (SOCE), and are essential for breast tumor cell migration. Our results showed that CO-OCS decreased the expression, at the protein level, of Stim1 without affecting that of Orai1. Moreover, cell migration and SOCE were attenuated by CO-OCS as well as when Stim1 was silenced. In contrast, in MCF-10A cells, CO-OCS slightly reduced cell migration, but was without effect on gene expression of Stim1, Orai1, β1-integrin, or FAK and ERK1/2 activation. Our results provide strong evidence for a significant effect of CO-OCS on breast cancer cell migration and support that this effect was associated with β1-integrin, Stim1, and FAK signaling pathways.
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http://dx.doi.org/10.1002/jcp.25832DOI Listing
December 2017

Functional cooperation between KCa3.1 and TRPC1 channels in human breast cancer: Role in cell proliferation and patient prognosis.

Oncotarget 2016 Jun;7(24):36419-36435

University of Picardie Jules Verne, UFR of Sciences, EA4667 Laboratory of Cell and Molecular Physiology, SFR CAP-SANTE (FED 4231), Amiens, France.

Intracellular Ca2+ levels are important regulators of cell cycle and proliferation. We, and others, have previously reported the role of KCa3.1 (KCNN4) channels in regulating the membrane potential and the Ca2+ entry in association with cell proliferation. However, the relevance of KC3.1 channels in cancer prognosis as well as the molecular mechanism of Ca2+ entry triggered by their activation remain undetermined. Here, we show that RNAi-mediated knockdown of KCa3.1 and/or TRPC1 leads to a significant decrease in cell proliferation due to cell cycle arrest in the G1 phase. These results are consistent with the observed upregulation of both channels in synchronized cells at the end of G1 phase. Additionally, knockdown of TRPC1 suppressed the Ca2+ entry induced by 1-EBIO-mediated KCa3.1 activation, suggesting a functional cooperation between TRPC1 and KCa3.1 in the regulation of Ca2+ entry, possibly within lipid raft microdomains where these two channels seem to co-localize. We also show significant correlations between KCa3.1 mRNA expression and poor patient prognosis and unfavorable clinical breast cancer parameters by mining large datasets in the public domain. Together, these results highlight the importance of KCa3.1 in regulating the proliferative mechanisms in breast cancer cells as well as in providing a promising novel target in prognosis and therapy.
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http://dx.doi.org/10.18632/oncotarget.9261DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5095010PMC
June 2016

Synthetic and Biological Studies of Sesquiterpene Polygodial: Activity of 9-Epipolygodial against Drug-Resistant Cancer Cells.

ChemMedChem 2015 Dec 5;10(12):2014-26. Epub 2015 Oct 5.

Department of Chemistry and Biochemistry, Texas State University, San Marcos, TX, 78666, USA.

Polygodial, a terpenoid dialdehyde isolated from Polygonum hydropiper L., is a known agonist of the transient receptor potential vanilloid 1 (TRPV1). In this investigation a series of polygodial analogues were prepared and investigated for TRPV1-agonist and anticancer activities. These experiments led to the identification of 9-epipolygodial, which has antiproliferative potency significantly exceeding that of polygodial. 9-Epipolygodial was found to maintain potency against apoptosis-resistant cancer cells as well as those displaying the multidrug-resistant (MDR) phenotype. In addition, the chemical feasibility for the previously proposed mechanism of action of polygodial, involving the formation of a Paal-Knorr pyrrole with a lysine residue on the target protein, was demonstrated by the synthesis of a stable polygodial pyrrole derivative. These studies reveal rich chemical and biological properties associated with polygodial and its direct derivatives. These compounds should inspire further work in this area aimed at the development of new pharmacological agents, or the exploration of novel mechanisms of covalent modification of biological molecules with natural products.
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http://dx.doi.org/10.1002/cmdc.201500360DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4831215PMC
December 2015

Wittig derivatization of sesquiterpenoid polygodial leads to cytostatic agents with activity against drug resistant cancer cells and capable of pyrrolylation of primary amines.

Eur J Med Chem 2015 Oct 29;103:226-37. Epub 2015 Aug 29.

Department of Chemistry and Biochemistry, Texas State University, San Marcos, TX 78666, USA. Electronic address:

Many types of cancer, including glioma, melanoma, non-small cell lung cancer (NSCLC), among others, are resistant to proapoptotic stimuli and thus poorly responsive to current therapies based on the induction of apoptosis in cancer cells. The current investigation describes the synthesis and anticancer evaluation of unique C12-Wittig derivatives of polygodial, a sesquiterpenoid dialdehyde isolated from Persicaria hydropiper (L.) Delabre. These compounds were found to undergo an unprecedented pyrrole formation with primary amines in a chemical model system, a reaction that could be relevant in the biological environment and lead to the pyrrolation of lysine residues in the target proteins. The anticancer evaluation of these compounds revealed their promising activity against cancer cells displaying various forms of drug resistance, including resistance to proapoptotic agents. Mechanistic studies indicated that compared to the parent polygodial, which displays fixative general cytotoxic action against human cells, the C12-Wittig derivatives exerted their antiproliferative action mainly through cytostatic effects explaining their activity against apoptosis-resistant cancer cells. The possibility for an intriguing covalent modification of proteins through a novel pyrrole formation reaction, as well as useful activities against drug resistant cancer cells, make the described polygodial-derived chemical scaffold an interesting new chemotype warranting thorough investigation.
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http://dx.doi.org/10.1016/j.ejmech.2015.08.047DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4617783PMC
October 2015

ORAI3 silencing alters cell proliferation and cell cycle progression via c-myc pathway in breast cancer cells.

Biochim Biophys Acta 2013 Mar 22;1833(3):752-60. Epub 2012 Dec 22.

University of Picardie Jules Verne, UFR of Sciences, Laboratory of Cellular and Molecular Physiology EA 4667, SFR CAP-SANTE, Amiens, France.

Members of the Orai family are highly selective calcium ion channels that play an important role in store-operated calcium entry. Among the three known Orai isoforms, Orai3 has gained increased attention, notably for its emerging role in cancer. We recently demonstrated that Orai3 channels are over-expressed in breast cancer (BC) biopsies, and involved specifically in proliferation, cell cycle progression and survival of MCF-7 BC cells. Here, we investigate the downstream signaling mechanisms affected by Orai3 silencing, leading to the subsequent functional impact specifically seen in MCF-7 cancer cells. We report a correlation between Orai3 and c-myc expression in tumor tissues and in the MCF-7 cancer cell line by demonstrating that Orai3 down-regulation reduces both expression and activity of the proto-oncogene c-myc. This is likely mediated through the MAP Kinase pathway, as we observed decreased pERK1/2 levels and cell-cycle arrest in G1 phase after Orai3 silencing. Our results provide strong evidence that the c-myc proto-oncogene is influenced by the store-operated calcium entry channel Orai3 through the MAP kinase pathway. This connection provides new clues in the downstream mechanism linking Orai3 channels and proliferation, cell cycle progression and survival of MCF-7 BC cells.
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http://dx.doi.org/10.1016/j.bbamcr.2012.12.009DOI Listing
March 2013

Transient receptor potential melastatin-related 7 channel is overexpressed in human pancreatic ductal adenocarcinomas and regulates human pancreatic cancer cell migration.

Int J Cancer 2012 Sep 17;131(6):E851-61. Epub 2012 Apr 17.

Laboratory of Cell and Molecular Physiology, Faculty of Sciences, University of Picardie Jules Verne, Amiens, France.

Pancreatic ductal adenocarcinoma (PDAC) is one of the most aggressive forms of cancer with a tendency to invade surrounding healthy tissues, leading to a largely incurable disease. Despite many advances in modern medicine, there is still a lack of early biomarkers as well as efficient therapeutical strategies. The melastatin-related transient receptor potential 7 channel (TRPM7) is a nonselective cation channel that is involved in maintaining Ca(2+) and Mg(2+) homeostasis. It has been recently reported to regulate cell differentiation, proliferation and migration. However, the role of TRPM7 in PDAC progression is far to be understood. In our study, we show that TRPM7 is 13-fold overexpressed in cancer tissues compared to the healthy ones. Furthermore, TRPM7 staining is stronger in tumors with high grade, suggesting a correlation between TRPM7 expression and PDAC progression. Importantly, TRPM7 expression is inversely related to patient survival. In BxPC-3 cell line, dialyzing the cytoplasm during the patch-clamp whole-cell recording with a 0-Mg(2+) solution activated a nonselective current with a strong outward rectification. This cation current is inhibited by intracellular Mg(2+) and by TRPM7 silencing. The downregulation of TRPM7 by small interference RNA dramatically inhibited intracellular Mg(2+) fluorescence and cell migration without affecting cell proliferation, suggesting that TRPM7 contributes to Mg(2+) entry and cell migration. Moreover, external Mg(2+) following TRPM7 silencing fully restored the cell migration. In summary, our results indicate that TRPM7 is involved in the BxPC-3 cell migration via a Mg(2+)-dependent mechanism and may be a potential biomarker of poor prognosis of PDAC.
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http://dx.doi.org/10.1002/ijc.27487DOI Listing
September 2012

Regulation of IGF-1-dependent cyclin D1 and E expression by hEag1 channels in MCF-7 cells: the critical role of hEag1 channels in G1 phase progression.

Biochim Biophys Acta 2011 May 16;1813(5):723-30. Epub 2011 Feb 16.

Laboratoire de Physiologie Cellulaire, JE2530, Université de Picardie Jules Verne, 33 Rue St Leu, Amiens, 80039, France.

Insulin-like Growth Factor-1 (IGF-1) plays a key role in breast cancer development and cell cycle regulation. It has been demonstrated that IGF-1 stimulates cyclin expression, thus regulating the G1 to S phase transition of the cell cycle. Potassium (K(+)) channels are involved in the G1 phase progression of the cell cycle induced by growth factors. However, mechanisms that allow growth factors to cooperate with K(+) channels in order to modulate the G1 phase progression and cyclin expression remain unknown. Here, we focused on hEag1 K(+) channels which are over-expressed in breast cancer and are involved in the G1 phase progression of breast cancer cells (MCF-7). As expected, IGF-1 increased cyclin D1 and E expression of MCF-7 cells in a cyclic manner, whereas the increase of CDK4 and 2 levels was sustained. IGF-1 stimulated p21(WAF1/Cip1) expression with a kinetic similar to that of cyclin D1, however p27(Kip1) expression was insensitive to IGF-1. Interestingly, astemizole, a blocker of hEag1 channels, but not E4031, a blocker of HERG channels, inhibited the expression of both cyclins after 6-8h of co-stimulation with IGF-1. However, astemizole failed to modulate CDK4, CDK2, p21(WAF1/Cip1) and p27(Kip1) expression. The down-regulation of hEag1 by siRNA provoked a decrease in cyclin expression. This study is the first to demonstrate that K(+) channels such as hEag1 are directly involved in the IGF-1-induced up-regulation of cyclin D1 and E expression in MCF-7 cells. By identifying more specifically the temporal position of the arrest site induced by the inhibition of hEag1 channels, we confirmed that hEag1 activity is predominantly upstream of the arrest site induced by serum-deprivation, prior to the up-regulation of both cyclins D1 and E. This article is part of a Special Issue entitled: 11th European Symposium on Calcium.
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http://dx.doi.org/10.1016/j.bbamcr.2011.01.025DOI Listing
May 2011

Down-regulation of Orai3 arrests cell-cycle progression and induces apoptosis in breast cancer cells but not in normal breast epithelial cells.

J Cell Physiol 2011 Feb;226(2):542-51

Laboratoire de Physiologie Cellulaire et Moléculaire, JE 2530: Canaux ioniques dans le Cancer du Sein, Faculté des Sciences, UPJV, Amiens, France.

Breast cancer (BC) is the leading cancer in the world in terms of incidence and mortality in women. However, the mechanism by which BC develops remains largely unknown. The increase in cytosolic free Ca(2+) can result in different physiological changes including cell growth and death. Orai isoforms are highly Ca(2+) selective channels. In the present study, we analyzed Orai3 expression in normal and cancerous breast tissue samples, and its role in MCF-7 BC and normal MCF-10A mammary epithelial cell lines. We found that the expression of Orai3 mRNAs was higher in BC tissues and MCF-7 cells than in normal tissues and MCF-10A cells. Down-regulation of Orai3 by siRNA inhibited MCF-7 cell proliferation and arrested cell cycle at G1 phase. This phenomenon is associated with a reduction in CDKs 4/2 (cyclin-dependent kinases) and cyclins E and D1 expression and an accumulation of p21(Waf1/Cip1) (a cyclin-dependent kinase inhibitor) and p53 (a tumor-suppressing protein). Orai3 was also involved in MCF-7 cell survival. Furthermore, Orai3 mediated Ca(2+) entry and contributed to intracellular calcium concentration ([Ca(2+)](i)). In MCF-10A cells, silencing Orai3 failed to modify [Ca(2+)](i), cell proliferation, cell-cycle progression, cyclins (D1, E), CDKs (4, 2), and p21(Waf1/Cip1) expression. Our results provide strong evidence for a significant effect of Orai3 on BC cell growth in vitro and show that this effect is associated with the induction of cell cycle and apoptosis resistance. Our study highlights a possible role of Orai3 as therapeutic target in BC therapy.
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http://dx.doi.org/10.1002/jcp.22363DOI Listing
February 2011

Extracellular signal-regulated kinases 1 and 2 and TRPC1 channels are required for calcium-sensing receptor-stimulated MCF-7 breast cancer cell proliferation.

Cell Physiol Biochem 2009 6;23(4-6):335-46. Epub 2009 May 6.

Laboratoire de Physiologie Cellulaire et Moléculaire, Faculté des Sciences, Université de Picardie Jules Verne, Amiens, France.

The calcium-sensing receptor (CaR), is a G protein-dependent receptor that responds to increments in extracellular Ca(2+) ([Ca(2+)](o)). We previously reported that an increase in [Ca(2+)](o) induced a release of intracellular calcium and Ca(2+) entry via store operated channels (SOCs). We also demonstrated that MCF-7 cells express Transient Receptor Potential canonical 1 (TRPC1) channels. Herein, we investigated CaR intracellular signaling pathways and examined the role of TRPC1 in CaR-induced cell proliferation, through the extracellular signal-regulated Kinases 1 & 2 (ERK1/2) pathways. Treatment by [Ca(2+)](o) increased both MCF-7 cell proliferation and TRPC1 expression. Both the [Ca(2+)](o) proliferative effect and TRPC1 protein levels were abolished by the ERK1/2 inhibitors. Moreover, [Ca(2+)](o) failed to increase cell proliferation either in the presence of CaR or TRPC1 siRNAs. Both [Ca(2+)](o) and the selective CaR activator spermine, elicited time and dose-dependent ERK1/2 phosphorylation. ERK1/2 phosphorylation was almost completely inhibited by treatment with the phospholipase C and the protein kinase C inhibitors. Treatment with 2-aminoethoxydiphenyl borate (2-APB), and SKF-96365 or by siTRPC1 diminished both [Ca(2+)](o)- and spermine-stimulated ERK1/2 phosphorylation. Moreover, down-regulation of TRPC1 by siRNA reduced the Ca(2+) entry induced by CaR activation. We conclude that the CaR activates ERK1/2 via a PLC/PKC-dependent pathway. Moreover, TRPC1 is required for the ERK1/2 phosphorylation, Ca(2+) entry and the CaR-proliferative effect.
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http://dx.doi.org/10.1159/000218179DOI Listing
August 2009

IGF-1 activates hEAG K(+) channels through an Akt-dependent signaling pathway in breast cancer cells: role in cell proliferation.

J Cell Physiol 2007 Sep;212(3):690-701

Laboratoire de Physiologie Cellulaire, EA 2086, Faculté des Sciences, Université de Picardie Jules Verne, Amiens, France.

Previous work from our laboratory has shown that human ether à go-go (hEAG) K(+) channels are crucial for breast cancer cell proliferation and cell cycle progression. In this study, we investigated the regulation of hEAG channels by an insulin-like growth factor-1 (IGF-1), which is known to stimulate cell proliferation. Acute applications of IGF-1 increased K(+) current-density and hyperpolarized MCF-7 cells. The effects of IGF-1 were inhibited by hEAG inhibitors. Moreover, IGF-1 increased mRNA expression of hEAG in a time-dependent manner in parallel with an enhancement of cell proliferation. The MCF-7 cell proliferation induced by IGF-1 is inhibited pharmacologically by Astemizole or Quinidine or more specifically using siRNA against hEAG channel. Either mitogen-activated protein kinase (MAPK) or phosphatidylinositol 3-kinase (PI3K) are known to mediate IGF-1 cell proliferative signals through the activation of extracellular signal-regulated kinase 1/2 (Erk 1/2) and Akt, respectively. In MCF-7 cells, IGF-1 rapidly stimulated Akt phosphorylation, whereas IGF-1 had little stimulating effect on Erk 1/2 which seems to be constitutively activated. The application of wortmannin was found to block the effects of IGF-1 on K(+) current. Moreover, the inhibition of Akt phosphorylation by the application of wortmannin or by a specific reduction of Akt kinase activity reduced the hEAG mRNA levels. Taken together, our results show, for the first time, that IGF-1 increases both the activity and the expression of hEAG channels through an Akt-dependent pathway. Since a hEAG channel is necessary for cell proliferation, its regulation by IGF-1 may thus play an important role in IGF-1 signaling to promote a mitogenic effect in breast cancer cells.
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http://dx.doi.org/10.1002/jcp.21065DOI Listing
September 2007

17-beta-estradiol activates maxi-K channels through a non-genomic pathway in human breast cancer cells.

FEBS Lett 2005 Jun;579(14):2995-3000

Laboratoire de Physiologie Cellulaire et Moléculaire, EA 2086, Université de Picardie Jules Verne, Faculté des Sciences, 33, Rue Saint-Leu 80039 Amiens, France.

We have investigated the acute effects of 17-beta-estradiol (E2) on K+ channels in MCF-7 breast epithelial cancer cells. E2 induced a rapid and irreversible augmentation of the K+ current for all membrane potentials superior to -25 mV. The effect of E2 was sensitive to Iberiotoxin, Charybdotoxin and TEA and can be elicited in the presence of the anti-estrogen ICI 182780 or be mimicked by the membrane impermeant form E2/BSA. Furthermore, E2/BSA was able to stimulate cell proliferation in a maxi-K inhibitors-sensitive manner. Thus, these results permit us to identify the maxi-K channel as the molecular target of E2 that regulates cell proliferation independently of the estrogen receptor.
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http://dx.doi.org/10.1016/j.febslet.2005.02.085DOI Listing
June 2005