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Milk-Derived miR-22-3p Promotes Proliferation of Human Intestinal Epithelial Cells (HIECs) by Regulating Gene Expression. Nutrients 2022; 14:nu14224901. [PMID: 36432587 PMCID: PMC9695551 DOI: 10.3390/nu14224901] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2022] [Revised: 11/09/2022] [Accepted: 11/15/2022] [Indexed: 11/22/2022] Open
Abstract
MicroRNA (miRNA) is small non-coding RNA involved in gene silencing and post-transcriptional regulation of gene expression. Milk exosomes are microvesicles containing microRNAs (miRNAs). miR-22-3p (miR-22) is plentiful in human milk exosomes and may contribute to intestinal development since milk exosomes and microRNAs are resistant to gastrointestinal digestion in infants. After miR-22 mimics were transfected to human intestinal crypt-like epithelial cells (HIECs) using Lipofectamine for 24 h, RNA was isolated for microarray assay. Microarray results show that miR-22 markedly regulates gene expression, and the roles of miR-22 include promotion of proliferation, regulation of immune functions, and inhibition of apoptosis. Based on the microarray results and miR-22 predicted target genes, CCAAT/enhancer-binding protein δ (C/EBPδ) may be an important direct target of miR-22. C/EBPδ is a transcription factor that regulates numerous biological processes including cell proliferation. In miR-22 transfected HIECs, expression of the C/EBPδ gene was significantly inhibited. Silencing of the C/EBPδ gene by siRNA resulted in increased proliferation of HIECs. A luciferase assay showed that miR-22 specifically binds to the 3'-untranslated region of C/EBPδ mRNA. In summary, milk-derived miR-22 promotes intestinal proliferation by modifying gene expression, and C/EBPδ may be an important target for miR-22 involved in this effect.
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Zhang R, Wu J, Ferrandon S, Glowacki KJ, Houghton JA. Targeting GLI by GANT61 involves mechanisms dependent on inhibition of both transcription and DNA licensing. Oncotarget 2018; 7:80190-80207. [PMID: 27863397 PMCID: PMC5348313 DOI: 10.18632/oncotarget.13376] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2016] [Accepted: 11/07/2016] [Indexed: 12/31/2022] Open
Abstract
The GLI genes are transcription factors and in cancers are oncogenes, aberrantly and constitutively activated. GANT61, a specific GLI inhibitor, has induced extensive cytotoxicity in human models of colon cancer. The FOXM1 promoter was determined to be a transcriptional target of GLI1. In HT29 cells, inhibition of GLI1 binding at the GLI consensus sequence by GANT61 led to inhibited binding of Pol II, the pause-release factors DSIF, NELF and p-TEFb. The formation of R-loops (RNA:DNA hybrids, ssDNA), were reduced by GANT61 at the FOXM1 promoter. Pretreatment of HT29 cells with α-amanitin reduced GANT61-induced γH2AX foci. Co-localization of GLI1 and BrdU foci, inhibited by GANT61, indicated GLI1 and DNA replication to be linked. By co-immunoprecipitation and confocal microscopy, GLI1 co-localized with the DNA licensing factors ORC4, CDT1, and MCM2. Significant co-localization of GLI1 and ORC4 was inhibited by GANT61, and enrichment of ORC4 occurred at the GLI binding site in the FOXM1 promoter. CDT1 was found to be a transcription target of GLI1. Overexpression of CDT1 in HT29 and SW480 cells reduced GANT61-induced cell death, gH2AX foci, and cleavage of caspase-3. Data demonstrate involvement of transcription and of DNA replication licensing factors by non-transcriptional and transcriptional mechanisms in the GLI-dependent mechanism of action of GANT61.
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Affiliation(s)
- Ruowen Zhang
- Department of Oncology, Division of Drug Discovery, Southern Research, Birmingham, AL, USA
| | - Jiahui Wu
- Lerner Research Institute, Cleveland Clinic, Cleveland, OH, USA
| | | | - Katie J Glowacki
- Department of Oncology, Division of Drug Discovery, Southern Research, Birmingham, AL, USA
| | - Janet A Houghton
- Department of Oncology, Division of Drug Discovery, Southern Research, Birmingham, AL, USA
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Rizzo P, Novelli R, Benigni A, Remuzzi G. Inhibiting angiotensin-converting enzyme promotes renal repair by modulating progenitor cell activation. Pharmacol Res 2016; 108:16-22. [PMID: 27095084 DOI: 10.1016/j.phrs.2016.04.009] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/24/2016] [Accepted: 04/13/2016] [Indexed: 11/18/2022]
Abstract
Independently of the initial insult, activation and accumulation of parietal progenitor cells within the Bowman's space is a peculiar feature of proliferative chronic kidney diseases. Clinical and experimental studies demonstrated that, in the presence of extensive renal damage, progenitor cells proliferate excessively in the failed attempt to replace the injured podocytes, contributing to the development of crescentic lesions. Inhibiting angiotensin-converting enzyme (ACE) halts crescent formation and promotes the restoration of normal glomerular architecture by limiting progenitor cell proliferation and migration towards the glomerular tuft. Among the mediators involved in the dysregulated response of renal precursors, the angiotensin II (ang II)/ang II type-1 (AT1) receptor/CXCR4 pathway have been demonstrated to be crucial in proliferative diseases. Understanding the mechanisms underlying the formation of crescentic lesions could be instrumental to developing new therapies, which can be more effective and more targeted to molecular mediators than the currently used cytotoxic agents.
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Affiliation(s)
- Paola Rizzo
- IRCCS-Istituto di Ricerche Farmacologiche Mario Negri, Centro Anna Maria Astori, Science and Technology Park Kilometro Rosso, Bergamo, Italy
| | - Rubina Novelli
- IRCCS-Istituto di Ricerche Farmacologiche Mario Negri, Centro Anna Maria Astori, Science and Technology Park Kilometro Rosso, Bergamo, Italy
| | - Ariela Benigni
- IRCCS-Istituto di Ricerche Farmacologiche Mario Negri, Centro Anna Maria Astori, Science and Technology Park Kilometro Rosso, Bergamo, Italy.
| | - Giuseppe Remuzzi
- IRCCS-Istituto di Ricerche Farmacologiche Mario Negri, Centro Anna Maria Astori, Science and Technology Park Kilometro Rosso, Bergamo, Italy; Unit of Nephrology and Dialysis, Azienda Ospedaliera Papa Giovanni XXIII, Bergamo, Italy; Department of Biomedical and Clinical Sciences, University of Milan, Milan, Italy
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Balamurugan K, Sterneck E. The many faces of C/EBPδ and their relevance for inflammation and cancer. Int J Biol Sci 2013; 9:917-33. [PMID: 24155666 PMCID: PMC3805898 DOI: 10.7150/ijbs.7224] [Citation(s) in RCA: 116] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2013] [Accepted: 08/27/2013] [Indexed: 12/29/2022] Open
Abstract
The CCAAT/enhancer binding protein delta (CEBPD, C/EBPδ) is a transcription factor that modulates many biological processes including cell differentiation, motility, growth arrest, proliferation, and cell death. The diversity of C/EBPδ's functions depends in part on the cell type and cellular context and can have opposing outcomes. For example, C/EBPδ promotes inflammatory signaling, but it can also inhibit pro-inflammatory pathways, and in a mouse model of mammary tumorigenesis, C/EBPδ reduces tumor incidence but promotes tumor metastasis. This review highlights the multifaceted nature of C/EBPδ's functions, with an emphasis on pathways that are relevant for cancer and inflammation, and illustrates how C/EBPδ emerged from the shadow of its family members as a fascinating “jack of all trades.” Our current knowledge on C/EBPδ indicates that, rather than being essential for a specific cellular process, C/EBPδ helps to interpret a variety of cues in a cell-type and context-dependent manner, to adjust cellular functions to specific situations. Therefore, insights into the roles and mechanisms of C/EBPδ signaling can lead to a better understanding of how the integration of different signaling pathways dictates normal and pathological cell functions and physiology.
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Affiliation(s)
- Kuppusamy Balamurugan
- Laboratory of Cell and Developmental Signaling, Center for Cancer Research, National Cancer Institute, Frederick, MD-21702-1201, U.S.A
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Genomic analysis of the role of transcription factor C/EBPδ in the regulation of cell behaviour on nanometric grooves. Biomaterials 2012; 34:1967-79. [PMID: 23245923 PMCID: PMC3543902 DOI: 10.1016/j.biomaterials.2012.11.036] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2012] [Accepted: 11/20/2012] [Indexed: 01/08/2023]
Abstract
C/EBPδ is a tumour suppressor transcription factor that induces gene expression involved in suppressing cell migration. Here we investigate whether C/EBPδ-dependent gene expression also affects cell responses to nanometric topology. We found that ablation of the C/EBPδ gene in mouse embryonal fibroblasts (MEFs) decreased cell size, adhesion and cytoskeleton spreading on 240 nm and 540 nm nanometric grooves. ChIP-SEQ and cDNA microarray analyses demonstrated that many binding sites for C/EBPδ, and the closely related C/EBPβ, exist throughout the mouse genome and control the upregulation or downregulation of many adjacent genes. We also identified a group of C/EBPδ-dependent, trans-regulated genes, whose promoters contained no C/EBPδ binding sites and yet their activity was regulated in a C/EBPδ-dependent manner. These genes include signalling molecules (e.g. SOCS3), cytoskeletal components (Tubb2, Krt16 and Krt20) and cytoskeletal regulators (ArhGEF33 and Rnd3) and are possibly regulated by cis-regulated diffusible mediators, such as IL6. Of particular note, SOCS3 was shown to be absolutely required for efficient cell spreading and contact guidance on 240 nm and 540 nm nanometric grooves. C/EBPδ is therefore involved in the complex regulation of multiple genes, including cytoskeletal components and signalling mediators, which influence the nature of cell interactions with nanometric topology.
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The CCAAT/enhancer-binding protein δ (C/EBP-δ) transcription factor is heat inducible in the cold-adapted antarctic fish Trematomus bernacchii. Polar Biol 2012. [DOI: 10.1007/s00300-012-1262-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Benigni A, Morigi M, Rizzo P, Gagliardini E, Rota C, Abbate M, Ghezzi S, Remuzzi A, Remuzzi G. Inhibiting angiotensin-converting enzyme promotes renal repair by limiting progenitor cell proliferation and restoring the glomerular architecture. THE AMERICAN JOURNAL OF PATHOLOGY 2011; 179:628-38. [PMID: 21718676 DOI: 10.1016/j.ajpath.2011.04.003] [Citation(s) in RCA: 90] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Received: 10/07/2010] [Revised: 03/16/2011] [Accepted: 04/22/2011] [Indexed: 11/18/2022]
Abstract
We previously reported that angiotensin-converting enzyme inhibitor (ACEi) renoprotection in Munich Wistar Frömter (MWF) rats, which develop progressive glomerular injury, was associated with podocyte repopulation and preservation of glomerular architecture. Here, we studied the time course of the lesions, their cellular components, and the effect of ACEi. Early glomerular lesions were synechiae, followed by extracapillary crescents and glomerulosclerosis. The majority of cells forming crescents were claudin1(+) parietal epithelial cells and, to a lesser extent, WT1(+) podocytes, both in active proliferation. In crescents, cells expressing the metanephric mesenchyme marker NCAM were also found. Three distinct populations of parietal epithelial cells were identified in the rat Bowman's capsule: NCAM(+)WT1(-) cells, also expressing progenitor cell marker CD24, and NCAM(+)WT1(+) and NCAM(-)WT1(+) cells, the latter population representing parietal podocytes. After exposure to inductive medium, cultured parietal epithelial cells that were obtained by capsulated glomeruli generated podocytes, documenting their progenitor nature. Mitotic activity of cultured renal progenitors was induced by angiotensin II through the down-regulation of cell cycle inhibitor C/EBPδ expression. Treatment with ACEi reduced number and extension of crescents and glomerulosclerosis in MWF rats. Renoprotection was accomplished through the limitation of NCAM(+) progenitor proliferation via the modulation of C/EBPδ. Thus, chaotic migration and proliferation of the Bowman's capsule progenitor cells pave the way to crescent formation and subsequent sclerosis. ACEi, by moderating progenitor cell activation, restores glomerular architecture and prevents renal disease progression.
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Affiliation(s)
- Ariela Benigni
- Mario Negri Institute for Pharmacological Research, Centro Anna Maria Astori, Bergamo, Italy
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Acute heat stress and thermal acclimation induce CCAAT/enhancer-binding protein delta in the goby Gillichthys mirabilis. J Comp Physiol B 2011; 181:773-80. [DOI: 10.1007/s00360-011-0572-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2010] [Revised: 02/28/2011] [Accepted: 03/12/2011] [Indexed: 11/25/2022]
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Yu X, Si J, Zhang Y, Dewille JW. CCAAT/Enhancer Binding Protein-delta (C/EBP-delta) regulates cell growth, migration and differentiation. Cancer Cell Int 2010; 10:48. [PMID: 21143913 PMCID: PMC3004888 DOI: 10.1186/1475-2867-10-48] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2010] [Accepted: 12/09/2010] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND CCAAT/enhancer binding protein-delta (C/EBP-delta) is a member of the highly conserved C/EBP family of basic region leucine zipper transcription factors. C/EBP family members regulate cell growth and differentiation and "loss of function" alterations in C/EBPs have been reported in a variety of human cancers. C/EBP-delta gene expression is upregulated by G0 growth arrest, IL-6 family cytokines and endotoxin treatments. C/EBP-delta exhibits properties of a tumor suppressor gene, including reduced expression and promoter methylation-induced silencing in transformed cell lines and primary tumors. In addition, C/EBP-delta gene expression is repressed by c-Myc, an oncogene that is over-expressed in a wide range of human cancers. "ChIP-chip" studies demonstrated that C/EBP-delta functions as a transcriptional activator of target genes that function in intracellular signal transduction, transcription, DNA binding/repair, cell cycle control, cell adhesion, and apoptosis. Despite progress in determining the biochemical functions of C/EBP-delta, the specific cellular defects that are induced by C/EBP-delta "loss of function" alterations are poorly understood. This study investigated the impact of C/EBP-delta "loss of function" alterations on growth arrest, migration/invasion and differentiation in nontransformed mouse mammary epithelial cells (MECs) and primary mouse embryo fibroblasts (MEFs). RESULTS C/EBP-delta siRNA transfected MECs exhibited ~90% reduction in C/EBP-delta mRNA and protein levels. C/EBP-delta siRNA treatment resulted in defective growth arrest as demonstrated by persistently elevated BrdU labeling, 3H-thymidine incorporation and cyclin D1 levels in response to growth arrest treatments. C/EBP-delta siRNA treatment also resulted in increased migration/invasion and defective differentiation. C/EBP-delta knockout MEFs exhibited defective growth arrest and increased proliferation/migration. Re-introduction of C/EBP-delta expression restored the growth arrest response of C/EBP-delta knockout MEFs. Finally, deletion of the C/EBP-delta DNA binding domain or the C/EBP-delta bZIP domain resulted in the loss of C/EBP-delta growth inhibition in clonogenic assays. CONCLUSIONS This study demonstrates that C/EBP-delta functions in the regulation of critical cell fate determining programs such as growth arrest, migration, and differentiation. These results support the tumor suppressor function of C/EBP-delta and identify potential mechanisms in which "loss of function" alterations in C/EBP-delta could promote cell transformation and tumorigenesis.
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Affiliation(s)
- Xueyan Yu
- Department of Veterinary Biosciences, Ohio State University College of Veterinary Medicine and OSU Comprehensive Cancer Center, 1925 Coffey Road, Columbus Ohio, 43210, USA.
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Borrelli S, Fanoni D, Dolfini D, Alotto D, Ravo M, Grober OMV, Weisz A, Castagnoli C, Berti E, Vigano MA, Mantovani R. C/EBPδ gene targets in human keratinocytes. PLoS One 2010; 5:e13789. [PMID: 21072181 PMCID: PMC2970548 DOI: 10.1371/journal.pone.0013789] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2010] [Accepted: 10/08/2010] [Indexed: 11/19/2022] Open
Abstract
C/EBPs are a family of B-Zip transcription factors -TFs- involved in the regulation of differentiation in several tissues. The two most studied members -C/EBPα and C/EBPβ- play important roles in skin homeostasis and their ablation reveals cells with stem cells signatures. Much less is known about C/EBPδ which is highly expressed in the granular layer of interfollicular epidermis and is a direct target of p63, the master regular of multilayered epithelia. We identified C/EBPδ target genes in human primary keratinocytes by ChIP on chip and profiling of cells functionally inactivated with siRNA. Categorization suggests a role in differentiation and control of cell-cycle, particularly of G2/M genes. Among positively controlled targets are numerous genes involved in barrier function. Functional inactivation of C/EBPδ as well as overexpressions of two TF targets -MafB and SOX2- affect expression of markers of keratinocyte differentiation. We performed IHC on skin tumor tissue arrays: expression of C/EBPδ is lost in Basal Cell Carcinomas, but a majority of Squamous Cell Carcinomas showed elevated levels of the protein. Our data indicate that C/EBPδ plays a role in late stages of keratinocyte differentiation.
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Affiliation(s)
- Serena Borrelli
- Dipartimento di Scienze Biomolecolari e Biotecnologie, Università degli Studi di Milano, Milano, Italy
| | - Daniele Fanoni
- Istituto di Scienze Dermatologiche, IRCCS Fondazione Ospedale Maggiore Policlinico, Mangiagalli e Regina Elena, Università degli Studi di Milano, Milano, Italy
| | - Diletta Dolfini
- Dipartimento di Scienze Biomolecolari e Biotecnologie, Università degli Studi di Milano, Milano, Italy
| | - Daniela Alotto
- Dipartimento di Chirurgia Plastica - Banca della Cute, Ospedale CTO, Torino, Italy
| | - Maria Ravo
- Dipartimento di Patologia Generale and Centro Grandi Apparecchiature, Seconda Università di Napoli, Napoli, Italy
| | - Olì Maria Victoria Grober
- Dipartimento di Patologia Generale and Centro Grandi Apparecchiature, Seconda Università di Napoli, Napoli, Italy
| | - Alessandro Weisz
- Dipartimento di Patologia Generale and Centro Grandi Apparecchiature, Seconda Università di Napoli, Napoli, Italy
- AIRC Naples Oncogenomics Centre, c/o CEINGE Biotecnologie Avanzate, Napoli, Italy
| | - Carlotta Castagnoli
- Dipartimento di Chirurgia Plastica - Banca della Cute, Ospedale CTO, Torino, Italy
| | - Emilio Berti
- Istituto di Scienze Dermatologiche, IRCCS Fondazione Ospedale Maggiore Policlinico, Mangiagalli e Regina Elena, Università degli Studi di Milano, Milano, Italy
- Università di Milano-Bicocca, Milano, Italy
| | - M. Alessandra Vigano
- Dipartimento di Scienze Biomolecolari e Biotecnologie, Università degli Studi di Milano, Milano, Italy
| | - Roberto Mantovani
- Dipartimento di Scienze Biomolecolari e Biotecnologie, Università degli Studi di Milano, Milano, Italy
- * E-mail:
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Ejarque-Ortiz A, Gresa-Arribas N, Straccia M, Mancera P, Solà C, Tusell JM, Serratosa J, Saura J. CCAAT/enhancer binding protein delta in microglial activation. J Neurosci Res 2010; 88:1113-23. [PMID: 19908286 DOI: 10.1002/jnr.22272] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The transcription factor CCAAT/enhancer binding protein delta (C/EBP delta) regulates transcription of genes that play important roles in glial activation. Previous studies have shown the astroglial expression of C/EBP delta but the microglial expression of C/EBP delta remains virtually unexplored, with the exception of two microarray studies. In this report, using murine primary cultures and BV2 cells we clearly demonstrate that C/EBP delta is expressed by microglia and it is upregulated in microglial activation. Lipopolysaccharide upregulates C/EBP delta both in microglia and in astrocytes. This effect is time-dependent, with a maximum effect at 3 hr at mRNA level and at 4-8 hr at protein level, and concentration-dependent, with a maximum effect at 100 ng/mL. The lipopolysaccharide-induced C/EBP delta upregulation in BV2 microglia is mimicked by agonists of the toll-like receptors 2, 3 and 9 and can be prevented by an inhibitor of extracellular signal-regulated kinase activation. C/EBP delta from activated BV2 microglia binds to the cyclooxygenase-2 promoter and forms complexes with C/EBP beta isoforms. These results point to C/EBP delta as a putative key regulator of proinflammatory gene expression in microglial activation.
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Affiliation(s)
- Aroa Ejarque-Ortiz
- Department of Cerebral Ischaemia and Neurodegeneration, IIBB, CSIC, IDIBAPS, Barcelona, Spain
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Si J, Yu X, Zhang Y, DeWille JW. Myc interacts with Max and Miz1 to repress C/EBPdelta promoter activity and gene expression. Mol Cancer 2010; 9:92. [PMID: 20426839 PMCID: PMC2879254 DOI: 10.1186/1476-4598-9-92] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2009] [Accepted: 04/28/2010] [Indexed: 12/18/2022] Open
Abstract
BACKGROUND "Loss of function" alterations in CCAAT/Enhancer Binding Proteindelta (C/EBPdelta) have been reported in a number of human cancers including breast, prostate and cervical cancer, hepatocellular carcinoma and acute myeloid leukemia. C/EBPdelta gene transcription is induced during cellular quiescence and repressed during active cell cycle progression. C/EBPdelta exhibits tumor suppressor gene properties including reduced expression in cancer cell lines and tumors and promoter methylation silencing. We previously reported that C/EBPdelta expression is inversely correlated with c-Myc (Myc) expression. Aberrant Myc expression is common in cancer and transcriptional repression is a major mechanism of Myc oncogenesis. A number of tumor suppressor genes are targets of Myc transcriptional repression including C/EBPalpha, p15INK4, p21CIP1, p27KIP1 and p57KIP2. This study investigated the mechanisms underlying Myc repression of C/EBPdelta expression. RESULTS Myc represses C/EBPdelta promoter activity in nontransformed mammary epithelial cells in a dose-dependent manner that requires Myc Box II, Basic Region and HLH/LZ domains. Chromatin Immunoprecipitation (ChIP) assays demonstrate that Myc, Miz1 and Max are associated with the C/EBPdelta promoter in proliferating cells, when C/EBPdelta expression is repressed. EMSAs demonstrate that Miz1 binds to a 30 bp region (-100 to -70) of the C/EBPdelta promoter which contains a putative transcription initiator (Inr) element. Miz1 functions exclusively as a repressor of C/EBPdelta promoter activity. Miz1 siRNA expression or expression of a Miz1 binding deficient Myc (MycV394D) construct reduces Myc repression of C/EBPdelta promoter activity. Max siRNA expression, or expression of a Myc construct lacking the HLH/LZ (Max interacting) region, also reduces Myc repression of C/EBPdelta promoter activity. Miz1 and Max siRNA treatments attenuate Myc repression of endogenous C/EBPdelta expression. Myc Box II interacting proteins RuvBl1 (Pontin, TIP49) and RuvBl2 (Reptin, TIP48) enhances Myc repression of C/EBPdelta promoter activity. CONCLUSION Myc represses C/EBPdelta expression by associating with the C/EBPdelta proximal promoter as a transient component of a repressive complex that includes Max and Miz1. RuvBl1 and RuvBl2 enhance Myc repression of C/EBPdelta promoter activity. These results identify protein interactions that mediate Myc repression of C/EBPdelta, and possibly other tumor suppressor genes, and suggest new therapeutic targets to block Myc transcriptional repression and oncogenic function.
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Affiliation(s)
- Junling Si
- Department of Veterinary Biosciences, Ohio State University College of Veterinary Medicine, Columbus, Ohio 43210, USA
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Filleur S, Hirsch J, Wille A, Schön M, Sell C, Shearer MH, Nelius T, Wieland I. INTS6/DICE1 inhibits growth of human androgen-independent prostate cancer cells by altering the cell cycle profile and Wnt signaling. Cancer Cell Int 2009; 9:28. [PMID: 19906297 PMCID: PMC2779787 DOI: 10.1186/1475-2867-9-28] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2009] [Accepted: 11/11/2009] [Indexed: 11/10/2022] Open
Abstract
Background The gene encoding integrator complex subunit 6 (INTS6), previously known as deleted in cancer cells 1 (DICE1, OMIM 604331) was found to be frequently affected by allelic deletion and promoter hypermethylation in prostate cancer specimens and cell lines. A missense mutation has been detected in prostate cancer cell line LNCaP. Together, these results suggest INTS6/DICE1 as a putative tumor suppressor gene in prostate cancer. In this study, we examined the growth inhibitory effects of INTS6/DICE1 on prostate cancer cells. Results Markedly decreased INTS6/DICE1 mRNA levels were detected in prostate cancer cell lines LNCaP, DU145 and PC3 as well as CPTX1532 as compared to a cell line derived from normal prostate tissue, NPTX1532. Exogenous re-expression of INTS6/DICE1 cDNA in androgen-independent PC3 and DU145 cell lines substantially suppressed their ability to form colonies in vitro. This growth inhibition was not due to immediate induction of apoptosis. Rather, prostate cancer cells arrested in G1 phase of the cell cycle. Expression profiling of members of the Wnt signaling pathway revealed up-regulation of several genes including disheveled inhibitor CXXC finger 4 (CXXC4), frizzled homologue 7 (FZD7), transcription factor 7-like 1 (TCF7L1), and down-regulation of cyclin D1. Conclusion These results show for the first time a link between INTS6/DICE1 function, cell cycle regulation and cell-cell communication involving members of the Wnt signaling pathway.
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Affiliation(s)
- Stephanie Filleur
- Texas Tech University Health Sciences Center, Department of Urology, Lubbock, TX, USA.
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