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A nutraceutical composition containing diosmin and hesperidin has osteogenic and anti-resorptive effects and expands the anabolic window of teriparatide. Biomed Pharmacother 2019; 118:109207. [DOI: 10.1016/j.biopha.2019.109207] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2019] [Revised: 06/27/2019] [Accepted: 07/02/2019] [Indexed: 02/05/2023] Open
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α 2A-Adrenergic Receptor Activation Decreases Parabrachial Nucleus Excitatory Drive onto BNST CRF Neurons and Reduces Their Activity In Vivo. J Neurosci 2018; 39:472-484. [PMID: 30478032 DOI: 10.1523/jneurosci.1035-18.2018] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2018] [Revised: 10/18/2018] [Accepted: 11/19/2018] [Indexed: 11/21/2022] Open
Abstract
Stress contributes to numerous psychiatric disorders. Corticotropin releasing factor (CRF) signaling and CRF neurons in the bed nucleus of the stria terminalis (BNST) drive negative affective behaviors, thus agents that decrease activity of these cells may be of therapeutic interest. Here, we show that acute restraint stress increases cFos expression in CRF neurons in the mouse dorsal BNST, consistent with a role for these neurons in stress-related behaviors. We find that activation of α2A-adrenergic receptors (ARs) by the agonist guanfacine reduced cFos expression in these neurons both in stressed and unstressed conditions. Further, we find that α- and β-ARs differentially regulate excitatory drive onto these neurons. Pharmacological and channelrhodopsin-assisted mapping experiments suggest that α2A-ARs specifically reduce excitatory drive from parabrachial nucleus (PBN) afferents onto CRF neurons. Given that the α2A-AR is a Gi-linked GPCR, we assessed the impact of activating the Gi-coupled DREADD hM4Di in the PBN on restraint stress regulation of BNST CRF neurons. CNO activation of PBN hM4Di reduced stress-induced Fos in BNST Crh neurons. Further, using Prkcd as an additional marker of BNST neuronal identity, we uncovered a female-specific upregulation of the coexpression of Prkcd/Crh in BNST neurons following stress, which was prevented by ovariectomy. These findings show that stress activates BNST CRF neurons, and that α2A-AR activation suppresses the in vivo activity of these cells, at least in part by suppressing excitatory drive from PBN inputs onto CRF neurons.SIGNIFICANCE STATEMENT Stress is a major variable contributing to mood disorders. Here, we show that stress increases activation of BNST CRF neurons that drive negative affective behavior. We find that the clinically well tolerated α2A-AR agonist guanfacine reduces activity of these cells in vivo, and reduces excitatory PBN inputs onto these cells ex vivo Additionally, we uncover a novel sex-dependent coexpression of Prkcd with Crh in female BNST neurons after stress, an effect abolished by ovariectomy. These results demonstrate input-specific interactions between norepinephrine and CRF, and point to an action by which guanfacine may reduce negative affective responses.
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La Colla A, Boland R, Vasconsuelo A. 17β-Estradiol Abrogates Apoptosis Inhibiting PKCδ, JNK, and p66Shc Activation in C2C12 Cells. J Cell Biochem 2016; 116:1454-65. [PMID: 25649128 DOI: 10.1002/jcb.25107] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2014] [Accepted: 01/26/2015] [Indexed: 12/17/2022]
Abstract
17β-Estradiol (E2) protects several non-reproductive tissues from apoptosis, including skeletal muscle. Previously, we showed that E2 at physiological concentrations prevented apoptosis induced by H2O2 in skeletal myoblasts. As we have also demonstrated a clear beneficial action of this hormone on skeletal muscle mitochondria, the present work further characterizes the signaling mechanisms modulated by E2 that are involved in mitochondria protection, which ultimately result in antiapoptosis. Here, we report that E2 through estrogen receptors (ERs) inhibited the H2O2-induced PKCδ and JNK activation, which results in the inhibition of phosphorylation and translocation to mitochondria of the adaptor protein p66Shc. In conjunction, the inhibition by the hormone of this H2O2-triggered signaling pathway results in protection of mitochondrial potential membrane. Our results provide basis for a putative mechanism by which E2 exerts beneficial effects on mitochondria, against oxidative stress, in skeletal muscle cells.
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Xu Y, Zou ST, Zhu R, Li W, Gu CW, Wei SH, Xie JM, Wu HR. Inhibition of proliferation of estrogen receptor‑positive MCF‑7 human breast cancer cells by tamoxifen through c‑Jun transcription factors. Mol Med Rep 2013; 7:1283-7. [PMID: 23404426 DOI: 10.3892/mmr.2013.1306] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2012] [Accepted: 01/21/2013] [Indexed: 11/06/2022] Open
Abstract
Activator of protein 1 (AP-1) is a heterodimeric transcription factor composed of various members of the Jun and Fos families and binds to DNA at specific AP-1 binding sites. AP-1 transcriptional activity is increased by phosphorylation at serine residues in the c‑Jun component of AP-1. In the present study, the proliferation of MCF-7 breast cancer cells was found to be suppressed by tamoxifen (TAM)-activated c-Jun through the protein kinase C (PKC) pathway. The molecular mechanism by which c‑Jun activation induces antiproliferative signals in estrogen receptor (ER)-positive MCF-7 human breast cancer cells remains unknown. TAM inhibited the proliferation of ER-positive MCF-7 human breast cancer cells and ER-negative MDA-MB-435 human breast cancer cells and 48 h incubation with 10 µM TAM led to inhibition of 80% of proliferation. In addition, no significant difference in c-Jun mRNA and protein levels was detected in MCF-7 and MDA-MB-435 cells stimulated by TAM for 48 h. TAM treatment of MCF-7 cells activated the transcriptional activity of AP-1, which responds specifically to phorbol ester. To determine the role of c-Jun in the antiproliferation of MCF-7 cells stimulated by TAM, the inhibition rates of MCF‑7 cells were correlated with c‑Jun expression and stimulation of TAM. Results showed that the inhibition rate of TAM-stimulated MCF-7 cells was positively regulated by overexpression of c-Jun and negatively regulated by underexpression of c-Jun. Overall, these results indicate that the TAM-stimulated antiproliferation of MCF-7 cells is positively regulated by c-Jun through activation of the PKC pathway.
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Affiliation(s)
- Yan Xu
- Department of General Surgery, Second Affiliated Hospital of Soochow University, Suzhou, Jiangsu 215004, P.R China
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Yu X, Zhang X, Dhakal IB, Beggs M, Kadlubar S, Luo D. Induction of cell proliferation and survival genes by estradiol-repressed microRNAs in breast cancer cells. BMC Cancer 2012; 12:29. [PMID: 22260523 PMCID: PMC3274428 DOI: 10.1186/1471-2407-12-29] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2011] [Accepted: 01/20/2012] [Indexed: 12/28/2022] Open
Abstract
Background In estrogen responsive MCF-7 cells, estradiol (E2) binding to ERα leads to transcriptional regulation of genes involved in the control of cell proliferation and survival. MicroRNAs (miRNAs) have emerged as key post-transcriptional regulators of gene expression. The aim of this study was to explore whether miRNAs were involved in hormonally regulated expression of estrogen responsive genes. Methods Western blot and QPCR were used to determine the expression of estrogen responsive genes and miRNAs respectively. Target gene expression regulated by miRNAs was validated by luciferase reporter assays and transfection of miRNA mimics or inhibitors. Cell proliferation was evaluated by MTS assay. Results E2 significantly induced bcl-2, cyclin D1 and survivin expression by suppressing the levels of a panel of miRNAs (miR-16, miR-143, miR-203) in MCF-7 cells. MiRNA transfection and luciferase assay confirmed that bcl-2 was regulated by miR-16 and miR-143, cyclinD1 was modulated by miR-16. Importantly, survivin was found to be targeted by miR-16, miR-143, miR-203. The regulatory effect of E2 can be either abrogated by anti-estrogen ICI 182, 780 and raloxifene pretreatment, or impaired by ERα siRNA, indicating the regulation is dependent on ERα. In order to investigate the functional significance of these miRNAs in estrogen responsive cells, miRNAs mimics were transfected into MCF-7 cells. It revealed that overexpression of these miRNAs significantly inhibited E2-induced cell proliferation. Further study of the expression of the miRNAs indicated that miR-16, miR-143 and miR-203 were highly expressed in triple positive breast cancer tissues, suggesting a potential tumor suppressing effect of these miRNAs in ER positive breast cancer. Conclusions These results demonstrate that E2 induces bcl-2, cyclin D1 and survivin by orchestrating the coordinate downregulation of a panel of miRNAs. In turn, the miRNAs manifest growth suppressive effects and control cell proliferation in response to E2. This sheds a new insight into the integral post-transcriptional regulation of cell proliferation and survival genes by miRNAs, a potential therapeutic option for breast cancer.
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Affiliation(s)
- Xinfeng Yu
- Department of Pharmacology, School of Chemical Biology & Pharmaceutical Sciences, Capital Medical University, 100069 Beijing, China.
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Nunes-Xavier CE, Elson A, Pulido R. Epidermal growth factor receptor (EGFR)-mediated positive feedback of protein-tyrosine phosphatase epsilon (PTPepsilon) on ERK1/2 and AKT protein pathways is required for survival of human breast cancer cells. J Biol Chem 2011; 287:3433-44. [PMID: 22117074 DOI: 10.1074/jbc.m111.293928] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Increased tyrosine phosphorylation has been correlated with human cancer, including breast cancer. In general, the activation of tyrosine kinases (TKs) can be antagonized by the action of protein-tyrosine phosphatases (PTPs). However, in some cases PTPs can potentiate the activation of TKs. In this study, we have investigated the functional role of PTPε in human breast cancer cell lines. We found the up-regulation and activation of receptor PTPε (RPTPε) in MCF-7 cells and MDA-MB-231 upon PMA, FGF, and serum stimulation, which depended on EGFR and ERK1/2 activity. Diminishing the expression of PTPε in human breast cancer cells abolished ERK1/2 and AKT activation, and decreased the viability and anchorage-independent growth of the cells. Conversely, stable MCF-7 cell lines expressing inducible high levels of ectopic PTPε displayed higher activation of ERK1/2 and anchorage-independent growth. Our results demonstrate that expression of PTPε is up-regulated and activated in breast cancer cell lines, through EGFR, by sustained activation of the ERK1/2 pathway, generating a positive feedback regulatory loop required for survival of human breast cancer cells.
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Simons R, Vincken JP, Mol LAM, The SAM, Bovee TFH, Luijendijk TJC, Verbruggen MA, Gruppen H. Agonistic and antagonistic estrogens in licorice root (Glycyrrhiza glabra). Anal Bioanal Chem 2011; 401:305-13. [PMID: 21573846 PMCID: PMC3124641 DOI: 10.1007/s00216-011-5061-9] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2011] [Revised: 04/21/2011] [Accepted: 04/25/2011] [Indexed: 01/06/2023]
Abstract
The roots of licorice (Glycyrrhiza glabra) are a rich source of flavonoids, in particular, prenylated flavonoids, such as the isoflavan glabridin and the isoflavene glabrene. Fractionation of an ethyl acetate extract from licorice root by centrifugal partitioning chromatography yielded 51 fractions, which were characterized by liquid chromatography-mass spectrometry and screened for activity in yeast estrogen bioassays. One third of the fractions displayed estrogenic activity towards either one or both estrogen receptors (ERs; ERα and ERβ). Glabrene-rich fractions displayed an estrogenic response, predominantly to the ERα. Surprisingly, glabridin did not exert agonistic activity to both ER subtypes. Several fractions displayed higher responses than the maximum response obtained with the reference compound, the natural hormone 17β-estradiol (E(2)). The estrogenic activities of all fractions, including this so-called superinduction, were clearly ER-mediated, as the estrogenic response was inhibited by 20-60% by known ER antagonists, and no activity was found in yeast cells that did not express the ERα or ERβ subtype. Prolonged exposure of the yeast to the estrogenic fractions that showed superinduction did, contrary to E(2), not result in a decrease of the fluorescent response. Therefore, the superinduction was most likely the result of stabilization of the ER, yeast-enhanced green fluorescent protein, or a combination of both. Most fractions displaying superinduction were rich in flavonoids with single prenylation. Glabridin displayed ERα-selective antagonism, similar to the ERα-selective antagonist RU 58668. Whereas glabridin was able to reduce the estrogenic response of E(2) by approximately 80% at 6 × 10(-6) M, glabrene-rich fractions only exhibited agonistic responses, preferentially on ERα.
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Affiliation(s)
- Rudy Simons
- Laboratory of Food Chemistry, Wageningen University, P.O. Box 8129, 6700 EV Wageningen, The Netherlands
- Frutarom Netherlands BV, Landjuweel 5, 3905 PE Veenendaal, The Netherlands
| | - Jean-Paul Vincken
- Laboratory of Food Chemistry, Wageningen University, P.O. Box 8129, 6700 EV Wageningen, The Netherlands
| | - Loes A. M. Mol
- Laboratory of Food Chemistry, Wageningen University, P.O. Box 8129, 6700 EV Wageningen, The Netherlands
| | - Susan A. M. The
- Laboratory of Food Chemistry, Wageningen University, P.O. Box 8129, 6700 EV Wageningen, The Netherlands
| | - Toine F. H. Bovee
- Department of Safety and Health, RIKILT-Institute of Food Safety, P.O. Box 230, 6700 AE Wageningen, The Netherlands
| | | | | | - Harry Gruppen
- Laboratory of Food Chemistry, Wageningen University, P.O. Box 8129, 6700 EV Wageningen, The Netherlands
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Jin H, Kanthasamy A, Anantharam V, Rana A, Kanthasamy AG. Transcriptional regulation of pro-apoptotic protein kinase Cdelta: implications for oxidative stress-induced neuronal cell death. J Biol Chem 2011; 286:19840-59. [PMID: 21467032 DOI: 10.1074/jbc.m110.203687] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
We previously demonstrated that protein kinase Cδ (PKCδ; PKC delta) is an oxidative stress-sensitive kinase that plays a causal role in apoptotic cell death in neuronal cells. Although PKCδ activation has been extensively studied, relatively little is known about the molecular mechanisms controlling PKCδ expression. To characterize the regulation of PKCδ expression, we cloned an ∼2-kbp 5'-promoter segment of the mouse Prkcd gene. Deletion analysis indicated that the noncoding exon 1 region contained multiple Sp sites, including four GC boxes and one CACCC box, which directed the highest levels of transcription in neuronal cells. In addition, an upstream regulatory region containing adjacent repressive and anti-repressive elements with opposing regulatory activities was identified within the region -712 to -560. Detailed mutagenesis studies revealed that each Sp site made a positive contribution to PKCδ promoter expression. Overexpression of Sp family proteins markedly stimulated PKCδ promoter activity without any synergistic transactivating effect. Furthermore, experiments in Sp-deficient SL2 cells indicated long isoform Sp3 as the essential activator of PKCδ transcription. Importantly, both PKCδ promoter activity and endogenous PKCδ expression in NIE115 cells and primary striatal cultures were inhibited by mithramycin A. The results from chromatin immunoprecipitation and gel shift assays further confirmed the functional binding of Sp proteins to the PKCδ promoter. Additionally, we demonstrated that overexpression of p300 or CREB-binding protein increases the PKCδ promoter activity. This stimulatory effect requires intact Sp-binding sites and is independent of p300 histone acetyltransferase activity. Finally, modulation of Sp transcriptional activity or protein level profoundly altered the cell death induced by oxidative insult, demonstrating the functional significance of Sp-dependent PKCδ gene expression. Collectively, our findings may have implications for development of new translational strategies against oxidative damage.
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Affiliation(s)
- Huajun Jin
- Parkinson's Disorder Research Laboratory, Iowa Center for Advanced Neurotoxicology, Department of Biomedical Sciences, Iowa State University, Ames, Iowa 50011, USA
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Brekman A, Singh KE, Polotskaia A, Kundu N, Bargonetti J. A p53-independent role of Mdm2 in estrogen-mediated activation of breast cancer cell proliferation. Breast Cancer Res 2011; 13:R3. [PMID: 21223569 PMCID: PMC3109566 DOI: 10.1186/bcr2804] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2010] [Revised: 11/17/2010] [Accepted: 01/11/2011] [Indexed: 12/14/2022] Open
Abstract
Introduction Estrogen receptor positive breast cancers often have high levels of Mdm2. We investigated if estrogen signaling in such breast cancers occurred through an Mdm2 mediated pathway with subsequent inactivation of p53. Methods We examined the effect of long-term 17β-estradiol (E2) treatment (five days) on the p53-Mdm2 pathway in estrogen receptor alpha (ERα) positive breast cancer cell lines that contain wild-type p53 (MCF-7 and ZR75-1). We assessed the influence of estrogen by examining cell proliferation changes, activation of transcription of p53 target genes, p53-chromatin interactions and cell cycle profile changes. To determine the effects of Mdm2 and p53 knockdown on the estrogen-mediated proliferation signals we generated MCF-7 cell lines with inducible shRNA for mdm2 or p53 and monitored their influence on estrogen-mediated outcomes. To further address the p53-independent effect of Mdm2 in ERα positive breast cancer we generated cell lines with inducible shRNA to mdm2 using the mutant p53 expressing cell line T-47D. Results Estrogen increased the Mdm2 protein level in MCF-7 cells without decreasing the p53 protein level. After estrogen treatment of MCF-7 cells, down-regulation of basal transcription of p53 target genes puma and p21 was observed. Estrogen treatment also down-regulated etoposide activated transcription of puma, but not p21. Mdm2 knockdown in MCF-7 cells increased p21 mRNA and protein, decreased cell growth in 3D matrigel and also decreased estrogen-induced cell proliferation in 2D culture. In contrast, knockdown of p53 had no effect on estrogen-induced cell proliferation. In T-47D cells with mutant p53, the knockdown of Mdm2 decreased estrogen-mediated cell proliferation but did not increase p21 protein. Conclusions Estrogen-induced breast cancer cell proliferation required a p53-independent role of Mdm2. The combined influence of genetic and environmental factors on the tumor promoting effects of estrogen implicated Mdm2 as a strong contributor to the bypass of cell cycle checkpoints. The novel finding that p53 was not the key target of Mdm2 in the estrogen activation of cell proliferation could have great benefit for future Mdm2-targeted breast cancer therapies.
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Affiliation(s)
- Angelika Brekman
- Department of Biological Sciences, Hunter College and The Graduate Center Biochemistry and Biology Programs, CUNY, 695 Park Ave, New York, NY 10065, USA
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Manna PR, Soh JW, Stocco DM. The involvement of specific PKC isoenzymes in phorbol ester-mediated regulation of steroidogenic acute regulatory protein expression and steroid synthesis in mouse Leydig cells. Endocrinology 2011; 152:313-25. [PMID: 21047949 PMCID: PMC3033061 DOI: 10.1210/en.2010-0874] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Protein kinase C (PKC) is a multigene family of serine/threonine kinases. PKC is involved in regulating adrenal and gonadal steroidogenesis; however, the functional relevance of the different PKC isoenzymes remains obscure. In this study, we demonstrate that MA-10 mouse Leydig tumor cells express several PKC isoforms to varying levels and that the activation of PKC signaling, by phorbol 12-myristate 13-acetate (PMA) elevated the expression and phosphorylation of PKCα, -δ, -ε, and -μ/protein kinase D (PKD). These responses coincided with the expression of the steroidogenic acute regulatory (StAR) protein and progesterone synthesis. Targeted silencing of PKCα, δ, and ε and PKD, using small interfering RNAs, resulted in deceases in basal and PMA-mediated StAR and steroid levels and demonstrated the importance of PKD in steroidogenesis. PKD was capable of controlling PMA and cAMP/PKA-mediated synergism involved in the steroidogenic response. Further studies pointed out that the regulatory events effected by PKD are associated with cAMP response element-binding protein (CREB) and c-Jun/c-Fos-mediated transcription of the StAR gene. Chromatin immunoprecipitation studies revealed that the activation of phosphorylated CREB, c-Jun, and c-Fos by PMA was correlated with in vivo protein-DNA interactions and the recruitment of CREB-binding protein, whereas knockdown of PKD suppressed the association of these factors with the StAR promoter. Ectopic expression of CREB-binding protein enhanced the trans-activation potential of CREB and c-Jun/c-Fos in StAR gene expression. Using EMSA, a -83/-67-bp region of the StAR promoter was shown to bind PKD-transfected MA-10 nuclear extract in a PMA-responsive manner, targeting CREB and c-Jun/c-Fos proteins. These findings provide evidence for the presence of multiple PKC isoforms and demonstrate the molecular events by which selective isozymes, especially PKD, influence PMA/PKC signaling involved in the regulation of the steroidogenic machinery in mouse Leydig cells.
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Affiliation(s)
- Pulak R Manna
- Department of Cell Biology and Biochemistry, Texas Tech University Health Sciences Center, Lubbock, Texas 79430, USA
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Napieralski R, Brünner N, Mengele K, Schmitt M. Emerging biomarkers in breast cancer care. Biomark Med 2010; 4:505-22. [DOI: 10.2217/bmm.10.73] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Currently, decision-making for breast cancer treatment in the clinical setting is mainly based on clinical data, histomorphological features of the tumor tissue and a few cancer biomarkers such as steroid hormone receptor status (estrogen and progesterone receptors) and oncoprotein HER2 status. Although various therapeutic options were introduced into the clinic in recent decades, with the objective of improving surgery, radiotherapy, biochemotherapy and chemotherapy, varying response of individual patients to certain types of therapy and therapy resistance is still a challenge in breast cancer care. Therefore, since breast cancer treatment should be based on individual features of the patient and her tumor, tailored therapy should be an option by integrating cancer biomarkers to define patients at risk and to reliably predict their course of the disease and/or response to cancer therapy. Recently, candidate-marker approaches and genome-wide transcriptomic and epigenetic screening of different breast cancer tissues and bodily fluids resulted in new promising biomarker panels, allowing breast cancer prognosis, prediction of therapy response and monitoring of therapy efficacy. These biomarkers are now subject of validation in prospective clinical trials.
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Affiliation(s)
- Rudolf Napieralski
- Clinical Research Unit, Department of Obstetrics & Gynecology, Klinikum rechts der Isar, Technische Universitaet Muenchen, Germany
| | - Nils Brünner
- University of Copenhagen, Faculty of Life Sciences, Department of Veterinary Disease Biology, Ridebanevej 9, DK-1870 Frederiksberg C, Denmark
| | - Karin Mengele
- Clinical Research Unit, Department of Obstetrics & Gynecology, Klinikum rechts der Isar, Technische Universitaet Muenchen, Germany
| | - Manfred Schmitt
- Clinical Research Unit, Department of Obstetrics & Gynecology, Ismaninger Strasse 22, Klinikum rechts der Isar, Technische Universitaet Muenchen, D-81675 Munich, Germany
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Nunes-Xavier CE, Tárrega C, Cejudo-Marín R, Frijhoff J, Sandin A, Ostman A, Pulido R. Differential up-regulation of MAP kinase phosphatases MKP3/DUSP6 and DUSP5 by Ets2 and c-Jun converge in the control of the growth arrest versus proliferation response of MCF-7 breast cancer cells to phorbol ester. J Biol Chem 2010; 285:26417-30. [PMID: 20554528 DOI: 10.1074/jbc.m110.121830] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Different levels of regulation account for the inactivation of MAP kinases by MAPK phosphatases (MKPs), in a cell type- and stimuli-dependent manner. MCF-7 human breast carcinoma cells treated with the phorbol 12-myristate 13-acetate (PMA) suffer growth arrest and show morphological alterations, which depend on the activation of the ERK1/2 MAP kinases. MKP3/DUSP6 and DUSP5 MAP kinase phosphatases, two negative regulators of ERK1/2, were specifically up-regulated in MCF-7 and SKBR3 cells in response to PMA. MKP3 and DUSP5 up-regulation required the prolonged activation of the ERK1/2 pathway, and correlated with the shutdown of this route. MKP3 induction relied on the activation of the Ets2 transcription factor, whereas DUSP5 induction depended on the activation of c-Jun. Diminishing the expression of MKP3 and DUSP5 raised the activation of ERK1/2, and accelerated growth arrest of PMA-treated MCF-7 cells. Conversely, MCF-7 cell lines expressing high levels of MKP3 or DUSP5 did not undergo PMA-triggered growth arrest, displayed a migratory phenotype, and formed colonies in soft agar. We propose that the differential up-regulation of MKP3 by Ets2 and of DUSP5 by c-Jun may converge in similar functional roles for these MAP kinase phosphatases in the growth arrest versus proliferation decisions of breast cancer cells.
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Xiao L, Gonzalez-Guerrico A, Kazanietz MG. PKC-mediated secretion of death factors in LNCaP prostate cancer cells is regulated by androgens. Mol Carcinog 2009; 48:187-195. [PMID: 18756441 DOI: 10.1002/mc.20476] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Activation of PKCdelta in androgen-dependent LNCaP prostate cancer cells leads to apoptosis via the activation of p38 MAPK and JNK cascades. We have recently shown that treatment of LNCaP cells with phorbol 12-myristate 13-acetate (PMA) leads to a PKCdelta-mediated autocrine release of death factors, including the cytokines TNFalpha and TRAIL, and that conditioned medium (CM) collected from PMA-treated LNCaP cells promotes the activation of the extrinsic apoptotic cascade. Interfering with this autocrine loop either at the level of factor release or death receptor activation/signaling markedly impaired the PMA apoptotic response. In the present study we show that this PKCdelta-dependent autocrine mechanism is greatly influenced by androgens. Indeed, upon androgen depletion, which down-regulates PKCdelta expression, TNFalpha and TRAIL mRNA induction and release by PMA are significantly diminished, resulting in a reduced apoptogenic activity of the CM and an impaired ability of the CM to activate p38 MAPK and JNK. These effects can be rescued by addition of the synthetic androgen R1881. Furthermore, RNAi depletion of the androgen-receptor (AR) from LNCaP cells equally impaired PMA responses, suggesting that PKC-mediated induction of death factor secretion and apoptosis in LNCaP prostate cancer cells are highly sensitive to hormonal control.
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Affiliation(s)
- Liqing Xiao
- Department of Pharmacology and Institute for Translational Medicine and Therapeutics (ITMAT), University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania
| | - Anatilde Gonzalez-Guerrico
- Department of Pharmacology and Institute for Translational Medicine and Therapeutics (ITMAT), University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania
| | - Marcelo G Kazanietz
- Department of Pharmacology and Institute for Translational Medicine and Therapeutics (ITMAT), University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania
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Perillo B, Ombra MN, Bertoni A, Cuozzo C, Sacchetti S, Sasso A, Chiariotti L, Malorni A, Abbondanza C, Avvedimento EV. DNA oxidation as triggered by H3K9me2 demethylation drives estrogen-induced gene expression. Science 2008; 319:202-6. [PMID: 18187655 DOI: 10.1126/science.1147674] [Citation(s) in RCA: 407] [Impact Index Per Article: 25.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Modifications at the N-terminal tails of nucleosomal histones are required for efficient transcription in vivo. We analyzed how H3 histone methylation and demethylation control expression of estrogen-responsive genes and show that a DNA-bound estrogen receptor directs transcription by participating in bending chromatin to contact the RNA polymerase II recruited to the promoter. This process is driven by receptor-targeted demethylation of H3 lysine 9 at both enhancer and promoter sites and is achieved by activation of resident LSD1 demethylase. Localized demethylation produces hydrogen peroxide, which modifies the surrounding DNA and recruits 8-oxoguanine-DNA glycosylase 1 and topoisomeraseIIbeta, triggering chromatin and DNA conformational changes that are essential for estrogen-induced transcription. Our data show a strategy that uses controlled DNA damage and repair to guide productive transcription.
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Affiliation(s)
- Bruno Perillo
- Istituto di Scienze dell'Alimentazione, Consiglio Nazionale delle Ricerche (C.N.R.), 83100 Avellino, Italy.
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15
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Assender JW, Gee JMW, Lewis I, Ellis IO, Robertson JFR, Nicholson RI. Protein kinase C isoform expression as a predictor of disease outcome on endocrine therapy in breast cancer. J Clin Pathol 2007; 60:1216-21. [PMID: 17965220 DOI: 10.1136/jcp.2006.041616] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
BACKGROUND Although in vitro breast cancer models have demonstrated a role for protein kinase C (PKC) alpha and delta isoforms in endocrine insensitivity and resistance respectively, there is currently little clinical evidence to support these observations. AIMS To define the pattern of PKC alpha and delta expression using breast cancer cell lines, with and without endocrine resistance, and also breast cancer samples, where expression can be correlated with clinicopathological and endocrine therapy outcome data. METHODS PKC isoform expression was examined in tamoxifen responsive, oestrogen receptor positive (ER(+)), ER(+) acquired tamoxifen resistant (TAM-R) and oestrogen receptor negative (ER(-)) cell lines by western blotting and immunocytochemical analysis. PKC isoform expression was then examined by immunohistochemistry in archival breast cancer specimens from primary breast cancer patients with known clinical outcome in relation to endocrine response and survival on therapy. RESULTS ER(+) breast cancer cell lines expressed considerable PKC-delta but barely detectable levels of PKC-alpha, whereas ER(-) cell lines expressed PKC-alpha but little PKC-delta. ER(+) acquired TAM-R cell lines expressed substantial levels of both PKC-alpha and delta. In clinical samples, high PKC-delta expression correlated to endocrine responsiveness whereas PKC-alpha expression correlated to ER negativity. PKC-delta was an independent predictor of duration of response to therapy. Patients showing a PKC-delta(+)/PKC-alpha(-) phenotype had a six times longer endocrine response than patients with the PKC-delta(+)/ PKC-alpha(+) phenotype (equating to tamoxifen resistance in vitro). CONCLUSIONS Levels of PKC-alpha and delta expression appear to be indicative of response to anti-oestrogen therapy and could be useful in predicting a patient's suitability for endocrine therapy.
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Affiliation(s)
- J W Assender
- CRUK Institute of Cancer Studies, University of Birmingham, Edgbaston, Birmingham, UK
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Roepke TA, Malyala A, Bosch MA, Kelly MJ, Rønnekleiv OK. Estrogen regulation of genes important for K+ channel signaling in the arcuate nucleus. Endocrinology 2007; 148:4937-51. [PMID: 17595223 DOI: 10.1210/en.2007-0605] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Estrogen affects the electrophysiological properties of a number of hypothalamic neurons by modulating K(+) channels via rapid membrane actions and/or changes in gene expression. The interaction between these pathways (membrane vs. transcription) ultimately determines the effects of estrogen on hypothalamic functions. Using suppression subtractive hybridization, we produced a cDNA library of estrogen-regulated, brain-specific guinea pig genes, which included subunits from three prominent K+ channels (KCNQ5, Kir2.4, Kv4.1, and Kvbeta(1)) and signaling molecules that impact channel function including phosphatidylinositol 3-kinase (PI3K), protein kinase Cepsilon (PKCepsilon), cAMP-dependent protein kinase (PKA), A-kinase anchor protein (AKAP), phospholipase C (PLC), and calmodulin. Based on these findings, we dissected the arcuate nucleus from ovariectomized guinea pigs treated with estradiol benzoate (EB) or vehicle and analyzed mRNA expression using quantitative real-time PCR. We found that EB significantly increased the expression of KCNQ5 and Kv4.1 and decreased expression of KCNQ3 and AKAP in the rostral arcuate. In the caudal arcuate, EB increased KCNQ5, Kir2.4, Kv4.1, calmodulin, PKCepsilon, PLCbeta(4), and PI3Kp55gamma expression and decreased Kvbeta(1). The effects of estrogen could be mediated by estrogen receptor-alpha, which we found to be highly expressed in the guinea pig arcuate nucleus and, in particular, proopiomelanocortin neurons. In addition, single-cell RT-PCR analysis revealed that about 50% of proopiomelanocortin and neuropeptide Y neurons expressed KCNQ5, about 40% expressed Kir2.4, and about 60% expressed Kv4.1. Therefore, it is evident that the diverse effects of estrogen on arcuate neurons are mediated in part by regulation of K(+) channel expression, which has the potential to affect profoundly neuronal excitability and homeostatic functions, especially when coupled with the rapid effects of estrogen on K(+) channel function.
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Affiliation(s)
- Troy A Roepke
- Department of Physiology and Pharmacology, Oregon Health & Science University, 3181 Southwest Sam Jackson Park Road, Portland, OR 97239, USA
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17
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O'Mahony F, Alzamora R, Betts V, LaPaix F, Carter D, Irnaten M, Harvey BJ. Female gender-specific inhibition of KCNQ1 channels and chloride secretion by 17beta-estradiol in rat distal colonic crypts. J Biol Chem 2007; 282:24563-73. [PMID: 17556370 DOI: 10.1074/jbc.m611682200] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
The estrogen sex steroid 17beta-estradiol rapidly inhibits secretagogue-stimulated cAMP-dependent Cl(-) secretion in the female rat distal colonic crypt by the inhibition of basolateral K(+) channels. In Ussing chamber studies, both the anti-secretory response and inhibition of basolateral K(+) current was shown to be attenuated by pretreatment with rottlerin, a PKCdelta-specific inhibitor. In whole cell patch-clamp analysis, 17beta-estradiol inhibited a chromanol 293B-sensitive KCNQ1 channel current in isolated female rat distal colonic crypts. Estrogen had no effect on KCNQ1 channel currents in colonic crypts isolated from male rats. Female distal colonic crypts expressed a significantly higher amount of PKCdelta in comparison to male tissue. PKCdelta and PKA were activated at 5 min in response to 17beta-estradiol in female distal colonic crypts only. Both PKCdelta- and PKA-associated with the KCNQ1 channel in response to 17beta-estradiol in female distal colonic crypts, and no associations were observed in crypts from males. PKA activation, association with KCNQ1, and phosphorylation of the channel were regulated by PKCdelta as the responses were blocked by pretreatment with rottlerin. Taken together, our experiments have identified the molecular targets underlying the anti-secretory response to estrogen involving the inhibition of KCNQ1 channel activity via PKCdelta- and PKA-dependent signaling pathways. This is a novel gender-specific mechanism of regulation of an ion channel by estrogen. The anti-secretory response described in this study provides molecular insights whereby estrogen causes fluid retention effects in the female during periods of high circulating plasma estrogen levels.
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Affiliation(s)
- Fiona O'Mahony
- Department of Molecular Medicine, Beaumont Hospital, Royal College of Surgeons in Ireland, Dublin 9, Ireland.
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18
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Kitatani K, Idkowiak-Baldys J, Hannun YA. Mechanism of inhibition of sequestration of protein kinase C alpha/betaII by ceramide. Roles of ceramide-activated protein phosphatases and phosphorylation/dephosphorylation of protein kinase C alpha/betaII on threonine 638/641. J Biol Chem 2007; 282:20647-56. [PMID: 17504762 DOI: 10.1074/jbc.m609162200] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Sustained activation of protein kinase C (PKC) isoenzymes alpha and betaII leads to their translocation to a perinuclear region and to the formation of the pericentrion, a PKC-dependent subset of recycling endosomes. In MCF-7 human breast cancer cells, the action of the PKC activator 4beta-phorbol-12-myristate-13-acetate (PMA) evokes ceramide formation, which in turn prevents PKCalpha/betaII translocation to the pericentrion. In this study we investigated the mechanisms by which ceramide negatively regulates this translocation of PKCalpha/betaII. Upon PMA treatment, HEK-293 cells displayed dual phosphorylation of PKCalpha/betaII at carboxyl-terminal sites (Thr-638/641 and Ser-657/660), whereas in MCF-7 cells PKCalpha/betaII were phosphorylated at Ser-657/660 but not Thr-638/641. Inhibition of ceramide synthesis by fumonisin B1 overcame the defect in PKC phosphorylation and restored translocation of PKCalpha/betaII to the pericentrion. To determine the involvement of ceramide-activated protein phosphatases in PKC regulation, we employed small interference RNA to silence individual Ser/Thr protein phosphatases. Knockdown of isoforms alpha or beta of the catalytic subunits of protein phosphatase 1 not only increased phosphorylation of PKCalpha/betaII at Thr-638/641 but also restored PKCbetaII translocation to the pericentrion. Mutagenesis approaches in HEK-293 cells revealed that mutation of either Thr-641 or Ser-660 to Ala in PKCbetaII abolished sequestration of PKC, implying the indispensable roles of phosphorylation of PKCalpha/betaII at those sites for their translocation to the pericentrion. Reciprocally, a point mutation of Thr-641 to Glu, which mimics phosphorylation, in PKCbetaII overcame the inhibitory effects of ceramide on PKC translocation in PMA-stimulated MCF-7 cells. Therefore, the results demonstrate a novel role for carboxyl-terminal phosphorylation of PKCalpha/betaII in the translocation of PKC to the pericentrion, and they disclose specific regulation of PKC autophosphorylation by ceramide through the activation of specific isoforms of protein phosphatase 1.
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Affiliation(s)
- Kazuyuki Kitatani
- Department of Biochemistry and Molecular Biology, Medical University of South Carolina, 173 Ashley Avenue, Charleston, SC 29425, USA
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19
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Karp G, Maissel A, Livneh E. Hormonal regulation of PKC: Estrogen up-regulates PKCη expression in estrogen-responsive breast cancer cells. Cancer Lett 2007; 246:173-81. [PMID: 16580129 DOI: 10.1016/j.canlet.2006.02.012] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2005] [Revised: 02/08/2006] [Accepted: 02/17/2006] [Indexed: 11/24/2022]
Abstract
Protein kinase C (PKC) is involved in several major signal transduction pathways that control gene expression cell growth and differentiation. The PKCeta isoform appears as a candidate regulator of mammary gland proliferation or differentiation, as its expression is up-regulated in the mammary gland in the transit from resting to the pregnant state. The purpose of this study was to examine the hormonal regulation of PKCeta. Here we show that estradiol specifically up-regulates the expression of PKCeta in the estrogen-responsive lines MCF-7 and T47D but not in the estrogen non-responsive line MDA-MB 231. Interestingly, the presence of progesterone, involved in the differentiation of the mammary gland, reduced the estrogen-induced PKCeta expression in a time-dependent manner. Thus, our studies suggest that PKCeta has an important role in signalling pathways regulating mammary gland proliferation and its development.
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Affiliation(s)
- Galia Karp
- Department of Microbiology and Immunology, Faculty of Health Sciences and the Cancer Research Center, Ben Gurion University, 84105 Beer Sheva, Israel
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20
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Gavrielides MV, Gonzalez-Guerrico AM, Riobo NA, Kazanietz MG. Androgens regulate protein kinase Cdelta transcription and modulate its apoptotic function in prostate cancer cells. Cancer Res 2007; 66:11792-801. [PMID: 17178875 DOI: 10.1158/0008-5472.can-06-1139] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Activation of protein kinase Cdelta (PKCdelta), a member of the novel PKC family, leads to apoptosis in several cell types. Although the molecular bases of PKCdelta activation are being unfolded, limited information is available on the mechanisms that control its expression. Here, we report that in prostate cancer cells PKCdelta is tightly regulated by androgens at the transcriptional level. Steroid depletion from the culture medium causes a pronounced down-regulation of PKCdelta protein and mRNA in androgen-sensitive LNCaP prostate cancer cells, an effect that is rescued by the androgen R1881 in an androgen receptor (AR)-dependent manner. Analysis of the PKCdelta promoter revealed a putative androgen responsive element (ARE) located 4.7 kb upstream from the transcription start site. Luciferase reporter assays show that this element is highly responsive to androgens, and mutations in key nucleotides in the AR-binding consensus abolish reporter activity. Furthermore, using chromatin immunoprecipitation assays, we determined that the AR binds in vivo to the PKCdelta ARE in response to androgen stimulation. Functional studies revealed that, notably, androgens modulate phorbol 12-myristate 13-acetate (PMA)-induced apoptosis in LNCaP cells, an effect that is dependent on PKCdelta. Indeed, androgen depletion or AR RNA interference severely impaired the apoptotic function of PKCdelta or the activation of p38, a downstream effector of PKCdelta in LNCaP cells--effects that can be rescued by restoring PKCdelta levels using an adenoviral delivery approach. Our studies identified a novel hormonal mechanism for the control of PKCdelta expression via transcriptional regulation that fine-tunes the magnitude of PKCdelta apoptotic responses.
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Affiliation(s)
- M Veronica Gavrielides
- Department of Pharmacology, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104, USA
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21
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Nguyen CH, Watts VJ. Dexamethasone-induced Ras protein 1 negatively regulates protein kinase C delta: implications for adenylyl cyclase 2 signaling. Mol Pharmacol 2006; 69:1763-71. [PMID: 16489124 DOI: 10.1124/mol.105.019133] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We identified dexamethasone-induced Ras protein 1 (Dexras1) as a negative regulator of protein kinase C (PKC) delta, and the consequences of this regulation have been examined for adenylyl cyclase (EC 4.6.1.1) type 2 (AC2) signaling. Dexras1 expression in human embryonic kidney 293 cells completely abolished dopamine D2 receptor-mediated potentiation of AC2 activity, which is consistent with previous reports of its ability to block receptor-mediated Gbetagamma signaling pathways. In addition, Dexras1 significantly reduced phorbol 12-myristate 13-acetate (PMA)-stimulated AC2 activity but did not alter Galpha(s)-mediated cAMP accumulation. Dexras1 seemed to inhibit PMA stimulation of AC2 by interfering with PKCdelta autophosphorylation. This effect was selective for the delta isoform because Dexras1 did not alter autophosphorylation of PKCalpha or PKCepsilon. Dexras1 disruption of PKCdelta autophosphorylation resulted in a significant blockade of PKC kinase activity as measured by [gamma-32P]ATP incorporation using a PKC-specific substrate. Moreover, Dexras1 and PKCdelta coimmunoprecipitated from whole-cell lysates. Dexras1 did not alter the membrane translocation of PKCdelta; however, the ability of Dexras1 to interfere with PKCdelta autophosphorylation was isoprenylation-dependent as determined using the farnesyltransferase inhibitor methyl {N-[2-phenyl-4-N [2(R)-amino-3-mecaptopropylamino] benzoyl]}-methionate (FTI-277) and a CAAX box-deficient Dexras1 (C277S) mutant. PMA-stimulated AC2 activity was also not affected by Dexras1 C277S. Taken as a whole, these data suggest that Dexras1 functionally interacts with PKCdelta at the cellular membrane through an isoprenylation-dependent mechanism to negatively regulate PKCdelta activity. Moreover our study suggests that Dexras1 acts to modulate the activation of AC2 in an indirect fashion by inhibiting both Gbetagamma- and PKC-stimulated AC2 activity. The current study provides a novel role for Dexras1 in signal transduction.
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Affiliation(s)
- Chau H Nguyen
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, 575 Stadium Mall Drive, RHPH 210, West Lafayette, IN 47907, USA
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22
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De Servi B, Hermani A, Medunjanin S, Mayer D. Impact of PKCdelta on estrogen receptor localization and activity in breast cancer cells. Oncogene 2005; 24:4946-55. [PMID: 15824731 DOI: 10.1038/sj.onc.1208676] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Regulation of estrogen receptor (ER) function in breast cancer cells is a complex process involving different signalling mechanisms. One signal transduction component that appears to influence ER signalling is protein kinase C (PKC). PKCdelta is a particular isoenzyme of the novel PKC subfamily that plays a role in growth control, differentiation and apoptosis. The aim of the present study was to investigate the impact of PKCdelta on the regulation of the transcriptional activity of the human ERalpha. By using 12-O-tetradecanoylphorbol-13-acetate (TPA), Bryostatin1 and Rottlerin, we show that active PKCdelta is a proproliferative factor in estrogen-dependent breast cancer cells. Furthermore, activation of PKCdelta by TPA resulted in activation and nuclear translocation of ERalpha and in an increase of ER-dependent reporter gene expression. Transfection and expression of the regulatory domain RDdelta of PKCdelta, which is inhibitory to PKCdelta, inhibited the TPA-induced ERalpha activation and translocation. ERalpha was not phosphorylated by PKCdelta; however, glycogen synthase kinase-3 (GSK3) was identified as a substrate of PKCdelta. The expression of RDdelta resulted in a decrease of TPA-induced GSK3 phosphorylation and translocation into the nucleus. We suggest that GSK3 plays a role in the PKCdelta-related nuclear translocation of ERalpha.
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Affiliation(s)
- Barbara De Servi
- Deutsches Krebsforschungszentrum, Hormones and Signal Transduction, Im Neuenheimer Feld 280, Heidelberg 69120, Germany
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23
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Devidze N, Pfaff DW, Kow LM. Potentiation of genomic actions of estrogen by membrane actions in mcf-7 cells and the involvement of protein kinase C activation. Endocrine 2005; 27:253-8. [PMID: 16230781 DOI: 10.1385/endo:27:3:253] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/06/2005] [Revised: 06/02/2005] [Accepted: 06/10/2005] [Indexed: 02/05/2023]
Abstract
It is now well established that estrogens (E) have at least two kinds of actions: genomic and nongenomic. But the relationship between these actions has hardly been explored. In this study we investigated this relationship in MCF-7 cells, a human breast cancer cell line, and explored the possible involvement of protein kinase C (PKC) signaling pathways. For this purpose a two-pulse paradigm was used: cells were treated with 17beta-estradiol (E), E conjugated with bovine serum albumin (E-BSA or fE'), or other test agents in the first pulse and with E in the second pulse following a 4-h interval. An E-BSA+E paradigm was used to show that replacement of E with the membrane-impermeable E-BSA in the first pulse could potentiate genomic actions of E, in the second pulse. To investigate involvement of signaling pathways, two PKC activators, phorbol 12,13-diacetate (PDAc) or phorbol 12-myristate 13-acetate (PMA), and inhibitors (chelerythrine chloride and H7-dihydrochloride) were used to replace E or E-BSA in the first pulse. PDAc was as effective as E or E-BSA in potentiating the genomic action of E in the second pulse, while PMA was almost without an effect. Conversely, the potentiating effects of E-BSA and PDAc were blocked by chelerythrine chloride but, interestingly, not by H7. The exact reason underlying these differences is not known. In summary, in MCF-7 cells a membrane action of E can potentiate a later genomic action and involves PKC signaling.
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Affiliation(s)
- Nino Devidze
- Laboratory of Neurobiology and Behavior, The Rockefeller University, New York, NY 10021, USA.
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24
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Nabha SM, Glaros S, Hong M, Lykkesfeldt AE, Schiff R, Osborne K, Reddy KB. Upregulation of PKC-delta contributes to antiestrogen resistance in mammary tumor cells. Oncogene 2005; 24:3166-76. [PMID: 15735693 DOI: 10.1038/sj.onc.1208502] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Acquired resistance to tamoxifen (Tam) in breast cancer patients is a serious therapeutic problem. We have previously reported that protein kinase C-delta (PKC-delta) plays a major role in estrogen (E2)-mediated cell proliferation. To determine if PKC-delta is one of the major alternate signaling pathways that supports cell growth in the presence of Tam, we determined the levels of PKC isoforms in four different models of antiestrogen-resistant cells. Three out of four antiestrogen resistance cell lines (Tam/MCF-7, ICI/MCF-7 and HER-2/MCF-7) expressed significantly high levels of both total and activated PKC-delta levels compared to sensitive cells. Estrogen receptor (ER) alpha content and function are maintained in all the antiestrogen-resistant cell lines. Overexpressing active PKC-delta in Tam-sensitive MCF-7 cells (PKC-delta/MCF-7) led to Tam resistance both in vitro and in vivo. Inhibition of PKC-delta by rottlerin (a relatively specific inhibitor of PKC-delta) or siRNA significantly inhibited estrogen- and Tam-induced growth in antiestrogen-resistant cells. PKC-delta levels are significantly higher in Tam-resistant tumors compared to Tam-sensitive tumors in xenograft model (P<0.05). Taken together, these data suggest that PKC-delta plays a major role in antiestrogen resistance in breast tumor cells and thus provides a new target for treatment.
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Affiliation(s)
- Sanaa M Nabha
- Department of Pathology, Wayne State University School of Medicine, 540 E. Canfield, Detroit, MI 48201, USA
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25
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Shin SY, Kim CG, Ko J, Min DS, Chang JS, Ohba M, Kuroki T, Choi YB, Kim YH, Na DS, Kim JW, Lee YH. Transcriptional and post-transcriptional regulation of the PKC delta gene by etoposide in L1210 murine leukemia cells: implication of PKC delta autoregulation. J Mol Biol 2004; 340:681-93. [PMID: 15223313 DOI: 10.1016/j.jmb.2004.04.006] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2003] [Revised: 03/29/2004] [Accepted: 04/06/2004] [Indexed: 10/26/2022]
Abstract
Protein kinase C delta (PKC delta) plays an important role in the regulation of apoptosis in response to diverse anticancer agents. PKC delta is cleaved irreversibly to a catalytically active fragment in response to apoptotic stimuli; however, little information is available about the regulation of PKC delta gene expression. In this study, we found that the amount of steady-state PKC delta mRNA and protein was increased by etoposide in mouse L1210 leukemia cells. The transcriptional rate of the PKC delta gene and the stability of PKC delta mRNA were increased by treatment with etoposide, resulting in the accumulation of PKC delta protein. Rottlerin inhibited etoposide-induced PKC delta gene expression significantly, while Go6976, LY294002 and PD98059 had no effect. Further, both stable and adenovirus-mediated expression of a dominant negative PKC delta(KR) abrogated etoposide-induced PKC delta expression. Etoposide-stimulated PKC delta transcription but not PKC delta mRNA stability was blocked completely by pretreatment with rottlerin. Our data reveal a novel mechanism whereby PKC delta gene is regulated at the transcriptional and post-transcriptional level in the L1210 leukemia cell line.
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Affiliation(s)
- Soon Young Shin
- Division of Molecular and Life Science, College of Science and Technology, Hanyang University, Ansan 426-791, South Korea
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Cheng CK, Chow BKC, Leung PCK. An activator protein 1-like motif mediates 17beta-estradiol repression of gonadotropin-releasing hormone receptor promoter via an estrogen receptor alpha-dependent mechanism in ovarian and breast cancer cells. Mol Endocrinol 2003; 17:2613-29. [PMID: 12947046 DOI: 10.1210/me.2003-0217] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Although it is recognized that estrogen is one of the most important regulators of GnRH receptor (GnRHR) gene expression, the mechanism underlying the regulation at the transcriptional level is unknown. In the present study, we demonstrated that 17beta-estradiol (E2) repressed human GnRHR promoter via an activator protein 1-like motif and estrogen receptor-alpha, of which the DNA-binding domain and the ligand-binding domain were indispensable for the repression. Interestingly, the same cis-acting motif was also found to be important for both the basal activity and phorbol 12-myristate 13-acetate responsiveness of the GnRHR promoter. EMSAs indicated that multiple transcription factors including c-Jun and c-Fos bound to the activator protein 1-like site and that their DNA binding activity was not significantly affected by E2 treatment. In addition, we demonstrated that the E2 repression could be antagonized by phorbol 12-myristate 13-acetate, which stimulated c-Jun phosphorylation on serine 63, a process that is a prerequisite for recruitment of the transcriptional coactivator cAMP response element binding protein (CREB)-binding protein (CBP). Concomitantly, we found that overexpression of CBP could reverse the suppression in a dose-dependent manner. Taken together, our data indicate that E2-activated estrogen receptor-alpha represses human GnRHR gene transcription via an indirect mechanism involving CBP and possibly other transcriptional regulators.
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Affiliation(s)
- Chi Keung Cheng
- Department of Obstetrics and Gynecology, University of British Columbia, Vancouver, Canada V6H 3V5
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Glaser S, Alvaro D, Ueno Y, Francis H, Marzioni M, Phinizy JL, Baumann B, Mancino MG, Venter J, LeSage G, Alpini G. Gastrin reverses established cholangiocyte proliferation and enhanced secretin-stimulated ductal secretion of BDL rats by activation of apoptosis through increased expression of Ca2+- dependent PKC isoforms. Liver Int 2003; 23:78-88. [PMID: 12698962 DOI: 10.1034/j.1600-0676.2003.00814.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/13/2023]
Abstract
UNLABELLED We posed these questions: (i) Does administration of gastrin to 1-week bile duct ligation (BDL) rats inhibits established cholangiocyte proliferation and ductal secretion? (ii) Is gastrin inhibition of cholangiocyte proliferation and secretion of BDL rats associated with enhanced apoptosis? (iii) Are gastrin's effects on cholangiocyte function associated with increased expression of protein kinase C (PKC) isoforms; and (iv) Is gastrin stimulation of cholangiocyte apoptosis regulated by the Ca2+-dependent PKC pathway? METHODS Seven days after BDL, rats were treated with gastrin by minipumps for 14 days. Cholangiocyte proliferation was assessed by measurement of the number of PCNA and CK-19 positive cholangiocytes in sections, and PCNA expression in cholangiocytes. Ductal secretion was determined by measurement of secretin-induced cAMP levels and choleresis. Apoptosis was evaluated by TUNEL analysis in sections and annexin-V staining in cholangiocytes. The expression of PKC isoforms was determined by immunoblots. RESULTS Gastrin inhibits established cholangiocyte proliferation and enhanced secretin-stimulated ductal secretion of BDL rats.Gastrin's effects on cholangiocyte function were associated with enhanced apoptosis and increased expression of PKC alpha, and beta I and II. Gastrin increases in cholangiocyte apoptosis were blocked by BAPTA/AM and H7. SUMMARY/CONCLUSION Gastrin inhibits cholangiocyte proliferation and secretin-induced ductal secretion in BDL rats by increasing apoptosis through a PKC-mediated mechanism.
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Affiliation(s)
- Sharon Glaser
- Division of Research and Education, Scott & White Hospital and The Texas A & M University System Health Science Center, College of Medicine, 76504, USA
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Glaser S, Alvaro D, Roskams T, Phinizy JL, Stoica G, Francis H, Ueno Y, Barbaro B, Marzioni M, Mauldin J, Rashid S, Mancino MG, LeSage G, Alpini G. Dopaminergic inhibition of secretin-stimulated choleresis by increased PKC-gamma expression and decrease of PKA activity. Am J Physiol Gastrointest Liver Physiol 2003; 284:G683-94. [PMID: 12505882 DOI: 10.1152/ajpgi.00302.2002] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
To determine the role and mechanisms of action by which dopaminergic innervation modulates ductal secretion in bile duct-ligated rats, we determined the expression of D1, D2, and D3 dopaminergic receptors in cholangiocytes. We evaluated whether D1, D2 (quinelorane), or D3 dopaminergic receptor agonists influence basal and secretin-stimulated choleresis and lumen expansion in intrahepatic bile duct units (IBDU) and cAMP levels in cholangiocytes in the absence or presence of BAPTA-AM, chelerythrine, 1-(5-isoquinolinylsulfonyl)-2-methyl piperazine (H7), or rottlerin. We evaluated whether 1) quinelorane effects on ductal secretion were associated with increased expression of Ca(2+)-dependent PKC isoforms and 2) increased expression of PKC causes inhibition of PKA activity. Quinelorane inhibited secretin-stimulated choleresis in vivo and IBDU lumen space, cAMP levels, and PKA activity in cholangiocytes. The inhibitory effects of quinelorane on secretin-stimulated ductal secretion and PKA activity were blocked by BAPTA-AM, chelerythrine, and H7. Quinelorane effects on ductal secretion were associated with activation of the Ca(2+)-dependent PKC-gamma but not other PKC isoforms. The dopaminergic nervous system counterregulates secretin-stimulated ductal secretion in experimental cholestasis.
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Affiliation(s)
- Shannon Glaser
- Department of Internal Medicine, Texas A&M University System Health Sciences Center, College of Medicine, Temple, Texas 76504, USA
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Driggers PH, Segars JH. Estrogen action and cytoplasmic signaling pathways. Part II: the role of growth factors and phosphorylation in estrogen signaling. Trends Endocrinol Metab 2002; 13:422-7. [PMID: 12431838 PMCID: PMC4152897 DOI: 10.1016/s1043-2760(02)00634-3] [Citation(s) in RCA: 185] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
In recent years, distinct signaling pathways involving specific complexes of cytoplasmic proteins have been shown to orchestrate estrogen action. These pathways might supplement or augment genomic effects of estrogen that are attributable to transcriptional activation by liganded receptor. Signals might be transduced through phosphorylation of the estrogen receptors (ERs), or indirectly through effects upon transcriptional coactivators or cell receptors. Estrogen signaling is coupled to growth factor signaling with feedback mechanisms directly impacting function of growth factor receptors. These signaling pathways regulate important physiological processes, such as cell growth and apoptosis. Here, we focus on cytoplasmic signaling pathways leading to activation of ERs.
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Affiliation(s)
- Paul H Driggers
- Dept of Obstetrics and Gynecology, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Rd, Bethesda, MD, USA.
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30
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Harvey BJ, Alzamora R, Healy V, Renard C, Doolan CM. Rapid responses to steroid hormones: from frog skin to human colon. A homage to Hans Ussing. BIOCHIMICA ET BIOPHYSICA ACTA 2002; 1566:116-28. [PMID: 12421543 DOI: 10.1016/s0005-2736(02)00589-8] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Fifty years ago, Hans Ussing described the mechanism by which ions are actively transported across frog skin. Since then, an enormous amount of effort has been invested in determining the cellular and molecular specifics of the transport mechanisms and their regulatory pathways. Ion transport in high-resistance epithelia is regulated by a variety of hormonal and non-hormonal factors. In vertebrates, steroid hormones such as mineralocorticoids, glucocorticoids and estrogens are major regulators of ion and water transport and hence are central to the control of extracellular fluid volume and blood pressure. Steroid hormones act through nuclear receptors to control the transcriptional activity of specific target genes, such as ion channels, ion transporters and ion pumps. These effects are observed after a latency of several hours and can last for days leading to cellular differentiation that allows a higher transport activity. This pathway is the so-called genomic phase. However, in the past 10 years, it has become apparent that steroid hormones can regulate electrolyte and water transport in tight epithelia independently of the transcription of these ion channels and transporters by regulating ion transporter activity in a non-genomic fashion via modulation of various signal transduction pathways. The molecular mechanisms underlying the steroid hormone-induced activation of signal transduction pathways such as protein kinase C (PKC), protein kinase A (PKA), intracellular calcium, intracellular pH and mitogen-activated protein kinases (MAPKs) and how non-genomic activation of these pathways influences epithelial ion transport will be discussed in this review.
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Affiliation(s)
- Brian J Harvey
- Molecular Medicine, Royal College of Surgeons in Ireland, 123 St. Stephens Green, Dublin 2, Ireland.
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31
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Shanmugam M, Krett NL, Maizels ET, Murad FM, Rosen ST, Hunzicker-Dunn M. A role for protein kinase C delta in the differential sensitivity of MCF-7 and MDA-MB 231 human breast cancer cells to phorbol ester-induced growth arrest and p21(WAFI/CIP1) induction. Cancer Lett 2001; 172:43-53. [PMID: 11595128 DOI: 10.1016/s0304-3835(01)00602-4] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The goal of this study was to investigate the differential sensitivity of estrogen receptor (ER) positive MCF-7 and ER negative MDA-MB 231 breast cancer cells to phorbol myristate acetate (PMA)-dependent growth arrest. MCF-7 cells were growth arrested by 80% while MDA-MB 231 cells were arrested by 20% in response to seven days of treatment with 10 nM PMA. Coincident with the increased sensitivity of MCF-7 cells to be growth arrested by the protein kinase C (PKC) activator PMA, PMA induced 9-fold higher levels of the cyclin dependent kinase (Cdk) inhibitor p21(WAF1/GIP1) in MCF-7 compared to MDA-MB 231 cells. A comparison of the PKC isoforms expressed in MCF-7 versus MDA-MB 231 cells showed that only the PMA-sensitive PKC delta and eta isoforms were expressed at markedly (> or =10-fold) elevated levels in MCF7 versus MDA-MB 231 cells. These results suggested that the differential sensitivity to growth arrest and induction of p2l(WAFl/CIPl) could reflect, at least in part, increased expression of PMA-dependent PKC isoforms delta and/or eta. Direct evidence to support this hypothesis was provided by the ability of transient transfections into MCF-7 cells of constitutively active PKC delta but not of PKC's eta or alpha or epsilon to enhance p21(WAFl/CIP1) promoter activity. These results suggest that PKC delta plays a fundamental role in the regulation of growth in estrogen receptor positive breast cancer cells.
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Affiliation(s)
- M Shanmugam
- Department of Cell and Molecular Biology, Northwestern University Medical School, 303 East Chicago Avenue, Chicago, IL 60611, USA
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32
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Allan GF, Hutchins A, Liu X, Clancy J. Induction of the progesterone receptor gene in estrogen target cells monitored by branched DNA signal amplification. Steroids 2001; 66:663-71. [PMID: 11546554 DOI: 10.1016/s0039-128x(01)00131-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
Estrogens have multiple effects on the growth and development of cells in their target tissues, including the uterus, ovary, breast, bone marrow and brain. The hormone regulates the transcription of diverse genes in these tissues via the estrogen receptor, a nuclear transcription factor. Naturally occurring estrogens and estrogen analogs including selective estrogen receptor modulators (SERMs), constitute important therapies for breast cancer and osteoporosis, and are major components of oral contraceptives. The in vitro biologic activities of pharmaceutical estrogen agonists and antagonists have frequently been monitored by cotransfection assay, where exogenous estrogen receptor and reporter genes are transiently inserted into a heterologous, non receptor-containing cell line, such as those derived from kidney cells. Here we describe an alternative to this method, where induction of an endogenous estrogen-responsive gene, the progesterone receptor gene, is monitored by branched DNA signal amplification. Assays are performed with cultured cells derived from estrogen-responsive tissues; namely, breast, uterine endothelium and bone. Hormonal induction occurs via the endogenous estrogen receptor of these cells. Our data show that SERMs, which are estrogen agonists on bone in vivo, antagonize estrogen-dependent target gene induction in conditionally immortalized osteoblast-like cells.
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Affiliation(s)
- G F Allan
- Reproductive Therapeutics, R.W. Johnson Pharmaceutical Research Institute, Raritan, New Jersey, USA.
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33
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Marino M, Distefano E, Caporali S, Ceracchi G, Pallottini V, Trentalance A. beta-estradiol stimulation of DNA synthesis requires different PKC isoforms in HepG2 and MCF7 cells. J Cell Physiol 2001; 188:170-7. [PMID: 11424083 DOI: 10.1002/jcp.1105] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The role exerted by protein kinase C (PKC) on estrogen-induced DNA synthesis has been investigated in hepatic and mammary gland cells, HepG2 and MCF7. 17-beta-estradiol stimulated DNA synthesis in HepG2 and MCF7 cells, maximal effect occurring at 10 nM. DNA synthesis stimulation was prevented by anti-estrogen ICI 182,780 and by inhibitor of PKC, Ro 31-8220. The rapid estradiol effects in MCF7 cells were determined by following the inositol trisphosphate (IP(3)) production and PKC-alpha membrane translocation. After estradiol treatment the increase of IP(3) production, prevented by anti-estrogen or by phospholipase C (PLC) inhibitor (neomycin), was present in MCF7 cells. In MDA cells, devoid of estrogen receptor, no effect was observed. The PKC-alpha presence on the membranes appeared unchanged in MCF7 cells. The PLC inhibitors, neomycin and U73,122, and PKC-alpha down regulator, phorbol 12-myristate 13-acetate (PMA), were able to prevent estradiol-induced DNA synthesis in hepatoma cells, but ineffective in mammary cells; wortmannin, an inhibitor of phosphoinositide 3-kinases (PI3-K), blocked DNA synthesis in both cell lines. These data show that beta-estradiol, via an estrogen receptor-mediated mechanism, activates more signal transduction pathways, and consequently different PKC isoforms in two responsive cell lines. In both cell lines PI3-K/PKC pathway is functional to the estrogen regulation of DNA synthesis, whereas in HepG2 cells the parallel involvement of the PLC/PKC-alpha pathway is present. The reported results indicate that the DNA synthesis stimulation by beta-estradiol requires the estrogen receptor and utilises one or more activated pathways in dependence on the cell equipment.
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Affiliation(s)
- M Marino
- Dipartimento di Biologia, Università "Roma Tre" Roma, Italy
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Abstract
In this study, the possible role of protein kinase C (PKC) in mediating both positive and negative actions on meiotic maturation in isolated mouse oocytes has been examined. When cumulus cell-enclosed oocytes (CEO) were cultured for 17-18 hr in a medium containing 4 mM hypoxanthine (HX) to maintain meiotic arrest, each of the five different activators and five different antagonists of PKC stimulated germinal vesicle breakdown (GVB) in a dose-dependent fashion. One of the activators, phorbol-12-myristate 13-acetate (PMA), also triggered GVB in CEO arrested with isobutylmethylxanthine or guanosine, but not in those arrested with dibutyryl cyclic AMP. When denuded oocytes (DO) were cultured for 3hr in inhibitor-free medium, all PKC activators suppressed maturation (<10% GVB compared to 94% in controls), while the effect of PKC antagonists was negligible. Four of the five antagonists reversed the meiosis-arresting action of HX in DO. PMA transiently arrested the spontaneous maturation of both CEO and DO, with greater potency in DO. The stimulatory action of PMA in HX-arrested oocytes was dependent on cumulus cells, because meiotic induction occurred in CEO but not DO. PKC activators also preferentially stimulated cumulus expansion when compared to antagonists. A cell-cell coupling assay determined that the action of PMA on oocyte maturation was not due to a loss of metabolic coupling between the oocyte and cumulus oophorus. Finally, Western analysis demonstrated the presence of PKCs alpha, beta1, delta, and eta in both cumulus cells and oocytes, but only PKC epsilon was detected in the cumulus cells. It is concluded that direct activation of PKC in the oocyte suppresses maturation, while stimulation within cumulus cells generates a positive trigger that leads to meiotic resumption.
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Affiliation(s)
- S M Downs
- Biology Department, Marquette University, Milwaukee, WI 53233, USA.
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Bähr C, Rohwer A, Stempka L, Rincke G, Marks F, Gschwendt M. DIK, a novel protein kinase that interacts with protein kinase Cdelta. Cloning, characterization, and gene analysis. J Biol Chem 2000; 275:36350-7. [PMID: 10948194 DOI: 10.1074/jbc.m004771200] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
A novel serine/threonine kinase, termed DIK, was cloned using the yeast two-hybrid system to screen a cDNA library from the human keratinocyte cell line HaCaT with the catalytic domain of rat protein kinase Cdelta (PKCdelta(cat)) cDNA as bait. The predicted 784-amino acid polypeptide with a calculated molecular mass of 86 kDa contains a catalytic kinase domain and a putative regulatory domain with ankyrin-like repeats and a nuclear localization signal. Expression of DIK at the mRNA and protein level could be demonstrated in several cell lines. The dik gene is located on chromosome 21q22.3 and possesses 8 exons and 7 introns. DIK was synthesized in an in vitro transcription/translation system and expressed as recombinant protein in bacteria, HEK, COS-7, and baculovirus-infected insect cells. In the in vitro system and in cells, but not in bacteria, various post-translationally modified forms of DIK were produced. DIK was shown to exhibit protein kinase activity toward autophosphorylation and substrate phosphorylation. The interaction of PKCdelta(cat) and PKCdelta with DIK was confirmed by coimmunoprecipitation of the proteins from HEK cells transiently transfected with PKCdelta(cat) or PKCdelta and DIK expression constructs.
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Affiliation(s)
- C Bähr
- German Cancer Research Center, D-69120 Heidelberg, Germany
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Jovanović S, Jovanović A, Shen WK, Terzic A. Low concentrations of 17beta-estradiol protect single cardiac cells against metabolic stress-induced Ca2+ loading. J Am Coll Cardiol 2000; 36:948-52. [PMID: 10987624 DOI: 10.1016/s0735-1097(00)00798-1] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
OBJECTIVES The main objective of the present study was to determine whether low physiological levels of estrogen directly protect cardiac cells against metabolic stress. BACKGROUND The beneficial effect of estrogens on the cardiovascular system has been traditionally ascribed to decrease in peripheral vascular resistance and to an antiatherogenic action. Whether physiological concentrations of 17beta-estradiol (E2) are also able to protect cardiomyocytes against metabolic insult directly is unknown. METHODS Isolated ventricular cardiomyocytes were loaded with the Ca2+-sensitive fluorescent dye Fluo-3 and imaged by a digital epifluorescence imaging system. In cardiac cells preincubated with hormones and/or drugs for 8 h, metabolic stress was induced by addition and removal of 2,4-dinitrophenol (DNP). RESULTS In cardiomyocytes, a 3-min-long exposure to chemical hypoxia, followed by reoxygenation, produced intracellular Ca2+ loading independently of gender (female: 729 +/- 88 nmol/liter; male: 778 +/- 97 nmol/liter). Pretreatment with E2 (10 nmol/liter) significantly reduced the magnitude of hypoxia/reoxygenation-induced Ca2+ loading in female (E2-treated: 298 +/- 39 nmol/liter; untreated: 729 +/- 88 nmol/liter), but not in male (E2-treated: 1029 +/- 177 nmol/liter; untreated: 778 +/- 97 nmol/liter) cardiac cells. The protective action of E2 was not mimicked by the inactive estrogen stereoisomer, 10 nmol/liter 17alpha estradiol (17alpha estradiol-treated: 886 +/- 122 nmol/liter; untreated: 729 +/- 88 nmol/liter), and was abolished by tamoxifen (1 micromol/liter), which acts as an antagonist of E2 on estrogen receptors (E2 plus tamoxifen-treated: 702 +/- 98 nmol/liter; untreated: 729 +/- 88 nmol/liter). CONCLUSIONS In a gender-dependent manner, E2 directly protects cardiac cells against hypoxia-reoxygenation injury through an estrogen receptor-mediated mechanism. Such property of E2 may contribute to cardioprotection in the female gender.
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Affiliation(s)
- S Jovanović
- Department of Internal Medicine, Mayo Clinic, Mayo Foundation, Rochester, Minnesota, USA
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Perillo B, Sasso A, Abbondanza C, Palumbo G. 17beta-estradiol inhibits apoptosis in MCF-7 cells, inducing bcl-2 expression via two estrogen-responsive elements present in the coding sequence. Mol Cell Biol 2000; 20:2890-901. [PMID: 10733592 PMCID: PMC85519 DOI: 10.1128/mcb.20.8.2890-2901.2000] [Citation(s) in RCA: 272] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We have found that 17beta-estradiol induces bcl-2 transcription in human breast cancer MCF-7 cells. To identify cis-acting elements involved in this regulation, we have analyzed hormone responsiveness of transiently transfected reporter constructs containing the bcl-2 major promoter (P(1)). Hormone inducibility was observed only when either of two sequences, located within the bcl-2 coding region and showing one and two mutations with respect to the consensus estrogen-responsive element, were inserted downstream from the P(1) promoter. Both sequences behaved as enhancers exclusively in cells expressing the estrogen receptor and were able to bind this receptor in in vitro assays. Transfections into MCF-7 cells of plasmids carrying a bcl-2 cDNA fragment which included these two elements revealed that their simultaneous presence resulted in an additive effect on reporter gene activity, whose size resembled the increase of endogenous bcl-2 mRNA level observed in untransfected cells after hormone treatment. Moreover, the identified elements were able to mediate up-regulation of bcl-2 expression by 17beta-estradiol, since exogenous bcl-2 mRNA was induced by hormone challenge of MCF-7 cells transiently transfected with a vector containing the bcl-2 coding sequence cloned under the control of a non-estrogen-responsive promoter. Finally, we show that hormone prevention of apoptosis, induced by incubating MCF-7 cells with hydrogen peroxide, was strictly related to bcl-2 up-regulation. Our results indicate that the bcl-2 major promoter does not contain cis-acting elements directly involved in transcriptional control by 17beta-estradiol and that hormone treatment inhibits programmed cell death in MCF-7 cells, inducing bcl-2 expression via two estrogen-responsive elements located within its coding region.
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Affiliation(s)
- B Perillo
- Centro di Endocrinologia ed Oncologia Sperimentale del C.N.R., Dipartimento di Biologia e Patologia Cellulare e Molecolare "L. Califano", Facoltà di Medicina e Chirurgia, Università "Federico II", 80131 Naples, Italy.
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