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Jiao Y, Wei J, Li Z, Zhou J, Liu Y. High FHL2 mRNA expression and its prognostic value in lung cancer. Aging (Albany NY) 2022; 14:7986-8000. [PMID: 36227138 PMCID: PMC9596202 DOI: 10.18632/aging.204328] [Citation(s) in RCA: 4] [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: 07/19/2022] [Accepted: 09/23/2022] [Indexed: 11/25/2022]
Abstract
BACKGROUND Lung cancer is the most frequent cancer globally with a high number of cancer-related deaths. The 4-and-a-half LIM domain protein 2 (FHL2) is an oncogenic gene, which promotes the proliferation, invasion, and metastasis of cancer cells. In this study, we aimed to demonstrate that lung cancer patients with high FHL2 expression have worse overall survival (OS) and relapse-free survival (RFS). METHODS TCGA was used to study FHL2 mRNA expression. Nomograms were used to predict the relationship between FHL2 expression levels and survival. The qRT-PCR was used to detect the FHL2 expression in lung cancer cells. In vitro experiments including CCK-8 assay, wound healing, and Transwell assay were performed. RESULTS This study comprised RNA-Seq gene expression data and clinical features for 1018 lung cancer patients. FHL2 was found to be overexpressed in lung cancer tissues. FHL2 demonstrated moderate diagnostic ability for lung cancer (AUC = 0.857). Kaplan-Meier curves and Cox regression analysis revealed the higher FHL2 expression with the poorer OS and RFS (P < 0.001). The nomogram results indicated that FHL2 could be used to predict the survival of lung cancer patients. GSEA analysis results show that high expression of FHL2 is related to glycolysis and unfolded protein reflection. FHL2 was highly expressed in lung cancer cells and related to their proliferation, migration, and invasion ability. CONCLUSIONS The high expression level of FHL2 in lung cancer can be used as an independent predictor of prognosis in clinical practice.
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Affiliation(s)
- Yan Jiao
- Department of Hepatobiliary and Pancreatic Surgery, General Surgery Center, The First Hospital of Jilin University, Changchun 130021, China
| | - Junyuan Wei
- The Key Laboratory of Pathobiology, Ministry of Education, College of Basic Medical Sciences, Jilin University, Changchun 130021, China
| | - Zhibin Li
- Department of Neurosurgery, The First Hospital of Jilin University, Changchun 130021, China
| | - Jintao Zhou
- Department of Thoracic Surgery, The First Hospital of Jilin University, Changchun 130021, China
| | - Yunpeng Liu
- Department of Thoracic Surgery, The First Hospital of Jilin University, Changchun 130021, China
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2
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Huang Z, Li Q, Luo K, Zhang Q, Geng J, Zhou X, Xu Y, Qian M, Zhang JA, Ji L, Wu J. miR-340-FHL2 axis inhibits cell growth and metastasis in ovarian cancer. Cell Death Dis 2019; 10:372. [PMID: 31068580 PMCID: PMC6506554 DOI: 10.1038/s41419-019-1604-3] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2019] [Revised: 04/07/2019] [Accepted: 04/19/2019] [Indexed: 12/24/2022]
Abstract
Although increasing evidence indicated that deregulation of microRNAs (miRNAs) contributed to tumor initiation and progression, but little is known about the biological role of miR-340 in ovarian cancer (OC). In this study, we found that miR-340 expression was downregulated in OC tissues compared with its expression in normal ovarian epithelium and endometrium, and treatment with 5-aza-2′-deoxycytidine (5-Aza-dC) or trichostatin A (TSA) increased miR-340 expression in OC cells. In addition, ectopic miR-340 expression inhibited OC cell growth and metastasis in vitro and in vivo. Four and a half LIM domains protein 2 (FHL2) was confirmed as a direct target of miR-340 and silencing FHL2 mimicked the effects of miR-340 in OC cells. Further mechanistic study showed that miR-340 inhibited the Wnt/β-catenin pathway by targeting FHL2, as well as downstream cell cycle and epithelial-to-mesenchymal transition (EMT) signals in OC cells. Moreover, the greatest association between miR-340 and FHL2 was found in 481 ovarian serous cystadenocarcinoma tissues via pan-cancer analysis. Finally, we revealed that lower miR-340 or higher FHL2 was associated with poor OC patient outcomes. Our findings indicate that the miR-340-FHL2 axis regulates Wnt/β-catenin signaling and is involved in tumorigenesis in OC. Therefore, manipulating the expression of miR-340 or its target genes is a potential strategy in OC therapy.
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Affiliation(s)
- Zheng Huang
- Institute of Genomic Medicine, Wenzhou Medical University, 325000, Wenzhou, Zhejiang, P. R. China
| | - Qiuxia Li
- Institute of Genomic Medicine, Wenzhou Medical University, 325000, Wenzhou, Zhejiang, P. R. China
| | - Kaili Luo
- Institute of Genomic Medicine, Wenzhou Medical University, 325000, Wenzhou, Zhejiang, P. R. China
| | - Qinkai Zhang
- Institute of Genomic Medicine, Wenzhou Medical University, 325000, Wenzhou, Zhejiang, P. R. China
| | - Jingwen Geng
- Institute of Genomic Medicine, Wenzhou Medical University, 325000, Wenzhou, Zhejiang, P. R. China
| | - Xunzhu Zhou
- Institute of Genomic Medicine, Wenzhou Medical University, 325000, Wenzhou, Zhejiang, P. R. China
| | - Yesha Xu
- Institute of Genomic Medicine, Wenzhou Medical University, 325000, Wenzhou, Zhejiang, P. R. China
| | - Mengyao Qian
- Institute of Genomic Medicine, Wenzhou Medical University, 325000, Wenzhou, Zhejiang, P. R. China
| | - Jian-An Zhang
- Department of Obstetrics and Gynecology, The Second Affiliated Hospital and Yuying Children of Wenzhou Medical University, 325027, Wenzhou, Zhejiang, P. R. China
| | - Liying Ji
- Institute of Genomic Medicine, Wenzhou Medical University, 325000, Wenzhou, Zhejiang, P. R. China
| | - Jianmin Wu
- Institute of Genomic Medicine, Wenzhou Medical University, 325000, Wenzhou, Zhejiang, P. R. China.
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Jin X, Jiao X, Jiao J, Zhang T, Cui B. Increased expression of FHL2 promotes tumorigenesis in cervical cancer and is correlated with poor prognosis. Gene 2018; 669:99-106. [PMID: 29800735 DOI: 10.1016/j.gene.2018.05.087] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2018] [Revised: 05/18/2018] [Accepted: 05/22/2018] [Indexed: 01/06/2023]
Abstract
PURPOSE Increasing evidence demonstrates that the four and a half LIM domain (FHL) gene and its protein products have different functions in the progression of various malignancies. However, the role of FHL protein 2 (FHL2) in cervical cancer (CC) has not been fully elucidated. In this study, we investigated the prognostic value of FHL2 expression in human CC tissues and the potential molecular mechanisms through which FHL2 modulates CC cell proliferation and apoptosis. MATERIALS AND METHODS We measured FHL2 expression in CC cell lines and tissues by quantitative real-time polymerase chain reaction and Western blot assays. The effects of FHL2 knockdown on cell proliferation and apoptosis in two CC cell lines were examined using RNA interference, cell counting kit-8, Western blot and flow cytometry assays. Furthermore, we assessed phosphorylated protein kinase B (p-AKT) and phosphorylated mammalian target of rapamycin (p-mTOR) expression in two CC cell lines to determine whether the AKT/mTOR pathway is involved in the effects of FHL2 silencing on cell proliferation and apoptosis. Nude mice tumorigenicity experiments were also performed to evaluate the effects of FHL2 on HeLa cell growth in vivo. RESULTS We found that FHL2 was significantly upregulated in CC cell lines and tissues. According to survival curves, high FHL2 expression levels in patients were correlated with poor prognosis. Moreover, by decreasing p-AKT and p-mTOR protein levels, silencing FHL2 significantly inhibited cell proliferation and induced apoptosis. FHL2 knockdown also induced apoptosis by increasing the Bax-to-Bcl2 ratio. By contrast, FHL2 overexpression significantly promoted cell proliferation. Finally, decreased tumour growth in an in vivo animal model also demonstrated the tumour-suppressing effects of FHL2 knockdown. CONCLUSION Our findings indicate that FHL2 is an important prognostic factor in CC and that it plays a crucial oncoprotein role by promoting cell proliferation and inhibiting apoptosis in CC, possibly by targeting the AKT/mTOR pathway.
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Affiliation(s)
- Xuejing Jin
- Department of Obstetrics and Gynecology, Qilu Hospital of Shandong University, Jinan 250012, China; Department of Obstetrics and Gynecology, Hangzhou Women's Hospital & Hangzhou Maternity and Child Health Care Hospital, Hangzhou 310000, China
| | - Xinlin Jiao
- Department of Obstetrics and Gynecology, Qilu Hospital of Shandong University, Jinan 250012, China
| | - Jun Jiao
- Department of Obstetrics and Gynecology, Qilu Hospital of Shandong University, Jinan 250012, China
| | - Teng Zhang
- Department of Obstetrics and Gynecology, Qilu Hospital of Shandong University, Jinan 250012, China
| | - Baoxia Cui
- Department of Obstetrics and Gynecology, Qilu Hospital of Shandong University, Jinan 250012, China.
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Abstract
Inhibitors of DNA binding and cell differentiation (Id) proteins are members of the large family of the helix-loop-helix (HLH) transcription factors, but they lack any DNA-binding motif. During development, the Id proteins play a key role in the regulation of cell-cycle progression and cell differentiation by modulating different cell-cycle regulators both by direct and indirect mechanisms. Several Id-protein interacting partners have been identified thus far, which belong to structurally and functionally unrelated families, including, among others, the class I and II bHLH transcription factors, the retinoblastoma protein and related pocket proteins, the paired-box transcription factors, and the S5a subunit of the 26 S proteasome. Although the HLH domain of the Id proteins is involved in most of their protein-protein interaction events, additional motifs located in their N-terminal and C-terminal regions are required for the recognition of diverse protein partners. The ability of the Id proteins to interact with structurally different proteins is likely to arise from their conformational flexibility: indeed, these proteins contain intrinsically disordered regions that, in the case of the HLH region, undergo folding upon self- or heteroassociation. Besides their crucial role for cell-fate determination and cell-cycle progression during development, other important cellular events have been related to the Id-protein expression in a number of pathologies. Dysregulated Id-protein expression has been associated with tumor growth, vascularization, invasiveness, metastasis, chemoresistance and stemness, as well as with various developmental defects and diseases. Herein we provide an overview on the structural properties, mode of action, biological function and therapeutic potential of these regulatory proteins.
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Affiliation(s)
- Cornelia Roschger
- Department of Molecular Biology, University of Salzburg, Billrothstrasse 11, Salzburg, 5020, Austria
| | - Chiara Cabrele
- Department of Molecular Biology, University of Salzburg, Billrothstrasse 11, Salzburg, 5020, Austria.
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Roschger C, Cabrele C. The Id-protein family in developmental and cancer-associated pathways. Cell Commun Signal 2017; 15:7. [PMID: 28122577 PMCID: PMC5267474 DOI: 10.1186/s12964-016-0161-y] [Citation(s) in RCA: 122] [Impact Index Per Article: 17.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2016] [Accepted: 12/29/2016] [Indexed: 01/15/2023] Open
Abstract
Inhibitors of DNA binding and cell differentiation (Id) proteins are members of the large family of the helix-loop-helix (HLH) transcription factors, but they lack any DNA-binding motif. During development, the Id proteins play a key role in the regulation of cell-cycle progression and cell differentiation by modulating different cell-cycle regulators both by direct and indirect mechanisms. Several Id-protein interacting partners have been identified thus far, which belong to structurally and functionally unrelated families, including, among others, the class I and II bHLH transcription factors, the retinoblastoma protein and related pocket proteins, the paired-box transcription factors, and the S5a subunit of the 26 S proteasome. Although the HLH domain of the Id proteins is involved in most of their protein-protein interaction events, additional motifs located in their N-terminal and C-terminal regions are required for the recognition of diverse protein partners. The ability of the Id proteins to interact with structurally different proteins is likely to arise from their conformational flexibility: indeed, these proteins contain intrinsically disordered regions that, in the case of the HLH region, undergo folding upon self- or heteroassociation. Besides their crucial role for cell-fate determination and cell-cycle progression during development, other important cellular events have been related to the Id-protein expression in a number of pathologies. Dysregulated Id-protein expression has been associated with tumor growth, vascularization, invasiveness, metastasis, chemoresistance and stemness, as well as with various developmental defects and diseases. Herein we provide an overview on the structural properties, mode of action, biological function and therapeutic potential of these regulatory proteins.
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Affiliation(s)
- Cornelia Roschger
- Department of Molecular Biology, University of Salzburg, Billrothstrasse 11, Salzburg, 5020, Austria
| | - Chiara Cabrele
- Department of Molecular Biology, University of Salzburg, Billrothstrasse 11, Salzburg, 5020, Austria.
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6
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Hua G, He C, Lv X, Fan L, Wang C, Remmenga SW, Rodabaugh KJ, Yang L, Lele SM, Yang P, Karpf AR, Davis JS, Wang C. The four and a half LIM domains 2 (FHL2) regulates ovarian granulosa cell tumor progression via controlling AKT1 transcription. Cell Death Dis 2016; 7:e2297. [PMID: 27415427 PMCID: PMC4973349 DOI: 10.1038/cddis.2016.207] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2016] [Revised: 05/04/2016] [Accepted: 05/24/2016] [Indexed: 12/14/2022]
Abstract
The four and a half LIM domains 2 (FHL2) has been shown to play important roles in the regulation of cell proliferation, survival, adhesion, motility and signal transduction in a cell type and tissue-dependent manner. However, the function of FHL2 in ovarian physiology and pathology is unclear. The aim of this study was to determine the role and functional mechanism of FHL2 in the progression of ovarian granulosa cell tumors (GCTs). Immunohistochemical analysis indicated that FHL2 was overexpressed in GCT tissues. Cellular localization of FHL2 in GCT cells was cell cycle dependent. Knockdown of FHL2 suppressed GCT cell growth, reduced cell viability and inhibited cell migration. Consistently, ectopic expression of FHL2 in GCT cells with very low endogenous FHL2 promoted cell growth, improved cell viability and enhance cell migration. Importantly, overexpression of FHL2 promoted GCT progression in vivo. Mechanistic studies indicated that FHL2 regulates AKT1 gene expression in vitro and in vivo. Knockdown of FHL2 or AKT1 in GCT cell lines induced very similar phenotypes. Ectopic expression of constitutively active AKT1 rescued FHL2 knockdown-induced arrest of GCT cell growth and reduction of GCT cell viability, suggesting that FHL2 regulates GCT cell growth and viability through controlling AKT1 expression. Finally, co-immunoprecipitation and chromatin immunoprecipitation analyses indicated that FHL2 functions as a co-activator of NFκB and AP-1 to regulate AKT1 gene transcription. In conclusion, results from the present study indicate that FHL2 exerts its oncogenic action in GCT cells via controlling AKT1 gene expression. FHL2 is a promising target for the development of novel drugs against ovarian granulosa cell tumor.
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Affiliation(s)
- G Hua
- Olson Center for Women's Health, Department of Obstetrics/Gynecology, University of Nebraska Medical Center, Omaha, NE 68198, USA.,Key Lab of Agricultural Animal Genetics, Breeding and Reproduction of Ministry of Education, College of Animal Science and Technology, Huazhong Agricultural University, Wuhan, Hubei province 430070, China
| | - C He
- Olson Center for Women's Health, Department of Obstetrics/Gynecology, University of Nebraska Medical Center, Omaha, NE 68198, USA.,Key Lab of Agricultural Animal Genetics, Breeding and Reproduction of Ministry of Education, College of Animal Science and Technology, Huazhong Agricultural University, Wuhan, Hubei province 430070, China
| | - X Lv
- Olson Center for Women's Health, Department of Obstetrics/Gynecology, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - L Fan
- Key Lab of Agricultural Animal Genetics, Breeding and Reproduction of Ministry of Education, College of Animal Science and Technology, Huazhong Agricultural University, Wuhan, Hubei province 430070, China
| | - C Wang
- Key Lab of Agricultural Animal Genetics, Breeding and Reproduction of Ministry of Education, College of Animal Science and Technology, Huazhong Agricultural University, Wuhan, Hubei province 430070, China
| | - S W Remmenga
- Olson Center for Women's Health, Department of Obstetrics/Gynecology, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - K J Rodabaugh
- Olson Center for Women's Health, Department of Obstetrics/Gynecology, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - L Yang
- Key Lab of Agricultural Animal Genetics, Breeding and Reproduction of Ministry of Education, College of Animal Science and Technology, Huazhong Agricultural University, Wuhan, Hubei province 430070, China
| | - S M Lele
- Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - P Yang
- Department of Obstetrics, Gynecology & Reproductive Sciences, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - A R Karpf
- Fred & Pamela Buffett Cancer Center, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - J S Davis
- Olson Center for Women's Health, Department of Obstetrics/Gynecology, University of Nebraska Medical Center, Omaha, NE 68198, USA.,Fred & Pamela Buffett Cancer Center, University of Nebraska Medical Center, Omaha, NE 68198, USA.,Omaha Veterans Affairs Medical Center, Omaha, NE 68105, USA
| | - C Wang
- Olson Center for Women's Health, Department of Obstetrics/Gynecology, University of Nebraska Medical Center, Omaha, NE 68198, USA.,Fred & Pamela Buffett Cancer Center, University of Nebraska Medical Center, Omaha, NE 68198, USA
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7
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Tran MK, Kurakula K, Koenis DS, de Vries CJM. Protein-protein interactions of the LIM-only protein FHL2 and functional implication of the interactions relevant in cardiovascular disease. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2015; 1863:219-28. [PMID: 26548523 DOI: 10.1016/j.bbamcr.2015.11.002] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 08/25/2015] [Revised: 11/02/2015] [Accepted: 11/03/2015] [Indexed: 11/26/2022]
Abstract
FHL2 belongs to the LIM-domain only proteins and contains four and a half LIM domains, each of which are composed of two zinc finger structures. FHL2 exhibits specific interaction with proteins exhibiting diverse functions, including transmembrane receptors, transcription factors and transcription co-regulators, enzymes, and structural proteins. The function of these proteins is regulated by FHL2, which modulates intracellular signal transduction pathways involved in a plethora of cellular tasks. The present review summarizes the current knowledge on the protein interactome of FHL2 and provides an overview of the functional implication of these interactions in apoptosis, migration, and regulation of nuclear receptor function. FHL2 was originally identified in the heart and there is extensive literature available on the role of FHL2 in the cardiovascular system, which is also summarized in this review.
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Affiliation(s)
- M Khang Tran
- Department of Medical Biochemistry, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Kondababu Kurakula
- Department of Medical Biochemistry, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Duco S Koenis
- Department of Medical Biochemistry, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Carlie J M de Vries
- Department of Medical Biochemistry, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands.
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8
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Abstract
Id (DNA binding and/or differentiation) proteins occur physiologically during ontogenesis and negatively regulate the activity of other helix-loop-helix (HLH) proteins. Id2 protein causes block of cells differentiation in the S phase of the cell cycle and regulates the activity of Rb protein. The role of Id2 protein in physiological cell cycle progression and in neuroblastoma (NBL) pathogenesis was proposed by Lasorella. The aim of the study was evaluation of Id2 expression and its prognostic significance in NBL cells coming from primary tumors and evaluation of its prognostic significance, and correlation of Id2 expression with known prognostic factors. Sixty patients with primary NBL treated from 1991 to 2005 were included in the analysis. We found 50 patients with high and 10 patients with low intensity of Id2 expression. The median percentage of NBL cells with Id2 expression was 88 %. We found no correlation between the number of NBL cells or the intensity of Id2 expression and OS and DFS. In patients with stage 4 NBL, almost all patients had high expression of Id2 and it was significantly more common than in other disease stages (p = 0,03). We found no correlation between Id2 expression and other known prognostic factor in NBL patients. We assume that Id2 is not prognostic factor. However, due to its abundant expression in most of NBL cells and its role in cell cycle, it may be potential therapeutic target. Exact knowledge of expression time may be helpful in explaining mechanisms of oncogenesis.
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Affiliation(s)
- Aleksandra Wieczorek
- Department of Pediatric Oncology and Hematology, Polish-American Institute of Pediatrics, Jagiellonian University Medical College, Krakow, Poland,
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9
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Zienert E, Eke I, Aust D, Cordes N. LIM-only protein FHL2 critically determines survival and radioresistance of pancreatic cancer cells. Cancer Lett 2015; 364:17-24. [PMID: 25917075 DOI: 10.1016/j.canlet.2015.04.019] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2015] [Revised: 04/17/2015] [Accepted: 04/19/2015] [Indexed: 11/27/2022]
Abstract
Numerous factors determine the current poor prognosis of pancreatic ductal adenocarcinoma (PDAC). One of the greatest challenges to overcome is treatment resistance. Among a large repertoire of intrinsic resistance mechanisms, integrin-mediated cell adhesion to extracellular matrix (ECM) has been identified to be fundamental. Coalesced in focal adhesion complexes, integrins, receptor tyrosine kinases, protein kinases and adapter proteins mediate prosurvival signaling. Four and a half LIM domains protein 2 (FHL2) is one of these adapter proteins, which operates through protein-protein interactions and shows tumor-specific expression. Based on this, we investigated FHL2 expression in PDAC specimens and three-dimensionally grown cell lines and how FHL2 mechanistically contributes to cell survival, cell cycling and radiation resistance. PDAC exhibited a significantly increased and heterogeneous FHL2 expression. Upon FHL2 depletion, pancreatic cancer cell lines showed significantly decreased cell survival, proliferation and radioresistance as well as enhanced apoptosis and MEK/ERK signaling and cyclin D1, E, A and B1 expression were strongly induced. Targeting of FHL2 and MEK1 was similarly effective than FHL2 depletion alone, suggesting MEK1 as a downstream signaling mediator of FHL2. Taken together, our results provide evidence for the importance of the focal adhesion protein FHL2 in pancreatic cancer cell survival, proliferation and radiosensitivity.
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Affiliation(s)
- Elisa Zienert
- OncoRay - National Center for Radiation Research in Oncology, Faculty of Medicine, University Hospital Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany
| | - Iris Eke
- OncoRay - National Center for Radiation Research in Oncology, Faculty of Medicine, University Hospital Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany; Department of Radiation Oncology, University Hospital Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany
| | - Daniela Aust
- Institute for Pathology, University Hospital Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany
| | - Nils Cordes
- OncoRay - National Center for Radiation Research in Oncology, Faculty of Medicine, University Hospital Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany; Institute of Radiooncology, Helmholtz-Zentrum Dresden - Rossendorf, Dresden, Germany; Department of Radiation Oncology, University Hospital Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany; German Cancer Consortium (DKTK), 01307 Dresden, Germany; German Cancer Research Center (DKFZ), Heidelberg, Germany.
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10
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Downregulation of Id2 increases chemosensitivity of glioma. Tumour Biol 2015; 36:4189-96. [DOI: 10.1007/s13277-015-3055-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2014] [Accepted: 01/02/2015] [Indexed: 11/24/2022] Open
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11
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Lu Y, Cai G, Cui S, Geng W, Chen D, Wen J, Zhang Y, Zhang F, Xie Y, Fu B, Chen X. FHL2-driven molecular network mediated Septin2 knockdown inducing apoptosis in mesangial cell. Proteomics 2014; 14:2485-97. [PMID: 25103794 DOI: 10.1002/pmic.201400252] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2014] [Revised: 07/22/2014] [Accepted: 08/04/2014] [Indexed: 01/20/2023]
Affiliation(s)
- Yang Lu
- Department of Nephrology; Chinese PLA General Hospital; Chinese PLA Institute of Nephrology; State Key Laboratory of Kidney Diseases; National Clinical Research Center of Kidney Diseases; Beijing P. R. China
| | - Guangyan Cai
- Department of Nephrology; Chinese PLA General Hospital; Chinese PLA Institute of Nephrology; State Key Laboratory of Kidney Diseases; National Clinical Research Center of Kidney Diseases; Beijing P. R. China
| | - Shaoyuan Cui
- Department of Nephrology; Chinese PLA General Hospital; Chinese PLA Institute of Nephrology; State Key Laboratory of Kidney Diseases; National Clinical Research Center of Kidney Diseases; Beijing P. R. China
| | - Wenjia Geng
- Department of Nephrology; Chinese PLA General Hospital; Chinese PLA Institute of Nephrology; State Key Laboratory of Kidney Diseases; National Clinical Research Center of Kidney Diseases; Beijing P. R. China
| | - Dapeng Chen
- Department of Nephrology; Chinese PLA General Hospital; Chinese PLA Institute of Nephrology; State Key Laboratory of Kidney Diseases; National Clinical Research Center of Kidney Diseases; Beijing P. R. China
| | - Jun Wen
- Department of Nephrology; Chinese PLA General Hospital; Chinese PLA Institute of Nephrology; State Key Laboratory of Kidney Diseases; National Clinical Research Center of Kidney Diseases; Beijing P. R. China
| | - Yuanyuan Zhang
- Department of Nephrology; Chinese PLA General Hospital; Chinese PLA Institute of Nephrology; State Key Laboratory of Kidney Diseases; National Clinical Research Center of Kidney Diseases; Beijing P. R. China
| | - Fujian Zhang
- Department of Nephrology; Chinese PLA General Hospital; Chinese PLA Institute of Nephrology; State Key Laboratory of Kidney Diseases; National Clinical Research Center of Kidney Diseases; Beijing P. R. China
| | - Yuansheng Xie
- Department of Nephrology; Chinese PLA General Hospital; Chinese PLA Institute of Nephrology; State Key Laboratory of Kidney Diseases; National Clinical Research Center of Kidney Diseases; Beijing P. R. China
| | - Bo Fu
- Department of Nephrology; Chinese PLA General Hospital; Chinese PLA Institute of Nephrology; State Key Laboratory of Kidney Diseases; National Clinical Research Center of Kidney Diseases; Beijing P. R. China
| | - Xiangmei Chen
- Department of Nephrology; Chinese PLA General Hospital; Chinese PLA Institute of Nephrology; State Key Laboratory of Kidney Diseases; National Clinical Research Center of Kidney Diseases; Beijing P. R. China
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12
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Lorda-Diez CI, Montero JA, Choe S, Garcia-Porrero JA, Hurle JM. Ligand- and stage-dependent divergent functions of BMP signaling in the differentiation of embryonic skeletogenic progenitors in vitro. J Bone Miner Res 2014; 29:735-48. [PMID: 24038612 DOI: 10.1002/jbmr.2077] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/09/2013] [Revised: 07/16/2013] [Accepted: 08/02/2013] [Indexed: 12/21/2022]
Abstract
Bone morphogenetic proteins (BMPs) are key molecules in the differentiation of skeletal tissues. We have investigated whether differentiation of limb embryonic mesodermal progenitors into different connective tissue lineages depends on specific stimulation of distinct BMP ligands or on the differential response of target cells to a common BMP stimulus. We show that Bmp2,4,5,7 and Gdf5 exhibit differential expression domains during the formation of tendons, cartilages, and joint tissues in digit development, but their respective effects on digit progenitors cell cultures cannot sustain the divergent differentiation of these cells into tendons, joints, and cartilage. However, the influence of BMPs differs based on the culture length. Early cultures respond to any of the BMPs by inducing chondrogenic factors and inhibiting fibrogenic and osteogenic markers. Later, a second phase of the culture occurs when BMPs attenuate their prochondrogenic influence and promote the fibrogenic marker Scleraxis. At advanced culture stages, BMPs inhibit prochondrogenic and profibrogenic markers and promote osteogenic markers. The switch from the prochondrogenic to the profibrogenic response appears critically dependent on the basal expression of Noggin. Thus, the differential regulation of Scleraxis at these stages was abrogated by treatments with a BMP-analogous compound (AB204) that escapes NOGGIN antagonism. Gene regulation experiments in absence of protein synthesis during the first period of culture indicate that BMPs activate at the same time master chondrogenic and fibrogenic genes together with cofactors responsible for driving the signaling cascade toward chondrogenesis or fibrogenesis. Gene-silencing experiments indicate that Id2 is one of the factors limiting the profibrogenic influence of BMPs. We propose that connective tissues are dynamic structures composed of cartilage, fibrous tissue, and bone that form in successive steps from the differentiation of common progenitors. This sequential differentiation is regulated by BMPs through a process that is dependent on the basal expression of BMP cofactors or signaling modulators.
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Affiliation(s)
- Carlos I Lorda-Diez
- Departamento de Anatomía y Biología Celular and IFIMAV, Universidad de Cantabria, Santander, Spain
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Verset L, Tommelein J, Moles Lopez X, Decaestecker C, Mareel M, Bracke M, Salmon I, De Wever O, Demetter P. Epithelial expression of FHL2 is negatively associated with metastasis-free and overall survival in colorectal cancer. Br J Cancer 2013; 109:114-20. [PMID: 23756870 PMCID: PMC3708555 DOI: 10.1038/bjc.2013.290] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2013] [Revised: 04/24/2013] [Accepted: 05/16/2013] [Indexed: 11/20/2022] Open
Abstract
Background: Four-and-a-half LIM domains protein 2 (FHL2) is a component of the focal adhesion structures and has been suggested to have a role in cancer progression. It has been shown to be overexpressed in the colorectal cancer (CRC). Methods: Here, we examined a possible prognostic value of FHL2 in CRC. Immunohistochemistry for FHL2 was performed on 296 CRCs without distant metastases at the time of surgery. Staining in the epithelial compartment was quantitatively evaluated using image analysis, and results were related to clinical variables. Antibody specificity was tested using small-interfering RNA transfection in hTERT-immortalised myofibroblasts. Results: Varying degrees of cytoplasmic FHL2 expression by neoplastic epithelial cells were detectable in all cases. Higher FHL2 expression in the epithelial compartment was an independent adverse prognostic factor. Multivariate Cox analysis shows that expression in the tumour invasion front (P<0.001) as well as in the centre of the tumour (P<0.001) was associated with metachronous metastases independently of the clinicopathological variables; expression in the tumour invasion front was also associated with overall survival independently of the clinicopathological variables (P<0.01). Conclusion: Higher FHL2 expression is involved in CRC progression and correlates with the development of metachronous metastases and overall survival, suggesting that FHL2 is an independent adverse prognostic indicator for CRC.
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Affiliation(s)
- L Verset
- Department of Pathology, Erasme University Hospital, Université Libre de Bruxelles, Route de Lennik 808, 1070 Brussels, Belgium
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Li X, Wu Z, Wang Y, Mei Q, Fu X, Han W. Characterization of adult α- and β-globin elevated by hydrogen peroxide in cervical cancer cells that play a cytoprotective role against oxidative insults. PLoS One 2013; 8:e54342. [PMID: 23349856 PMCID: PMC3547883 DOI: 10.1371/journal.pone.0054342] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2012] [Accepted: 12/12/2012] [Indexed: 12/11/2022] Open
Abstract
Objectives Hemoglobin (Hgb) is the main oxygen and carbon dioxide carrier in cells of erythroid lineage and is responsible for oxygen delivery to the respiring tissues of the body. However, Hgb is also expressed in nonerythroid cells. In the present study, the expression of Hgb in human uterine cervix carcinoma cells and its role in cervical cancer were investigated. Methodology The expression level of Hgb in cervical cancer tissues was assessed by quantitative reverse transcriptase-PCR (qRT-PCR). We applied multiple methods, such as RT-PCR, immunoblotting, and immunohistochemical analysis, to confirm Hgb expression in cervical cancer cells. The effects of ectopic expression of Hgb and Hgb mutants on oxidative stress and cell viability were investigated by cellular reactive oxygen species (ROS) analysis and lactate dehydrogenase (LDH) array, respectively. Both Annexin V staining assay by flow cytometry and caspase-3 activity assay were used, respectively, to evaluate cell apoptosis. Results qRT-PCR analysis showed that Hgb-α- (HBA1) and Hgb-β-globin (HBB) gene expression was significantly higher in cervical carcinoma than in normal cervical tissues, whereas the expression of hematopoietic transcription factors and erythrocyte specific marker genes was not increased. Immunostaining experiments confirmed the expression of Hgb in cancer cells of the uterine cervix. Hgb mRNA and protein were also detected in the human cervical carcinoma cell lines SiHa and CaSki, and Hgb expression was up-regulated by hydrogen peroxide-induced oxidative stress. Importantly, ectopic expression of wild type HBA1/HBB or HBA1, rather than mutants HBA1H88R/HBBH93R unable to bind hemo, suppressed oxidative stress and improved cell viability. Conclusions The present findings show for the first time that Hgb is expressed in cervical carcinoma cells and may act as an antioxidant, attenuating oxidative stress-induced damage in cervical cancer cells. These data provide a significant impact not only in globin biology but also in understanding of cervical cancer pathogenesis associated with oxidative stress.
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Affiliation(s)
- Xiaolei Li
- Department of Molecular Biology, Institute of Basic Medicine, School of Life Sciences, Chinese PLA General Hospital, Beijing, China
| | - Zhiqiang Wu
- Department of Molecular Biology, Institute of Basic Medicine, School of Life Sciences, Chinese PLA General Hospital, Beijing, China
| | - Yao Wang
- Department of Immunology, Institute of Basic Medicine, School of Life Sciences, Chinese PLA General Hospital, Beijing, China
| | - Qian Mei
- Department of Molecular Biology, Institute of Basic Medicine, School of Life Sciences, Chinese PLA General Hospital, Beijing, China
| | - Xiaobing Fu
- Department of Molecular Biology, Institute of Basic Medicine, School of Life Sciences, Chinese PLA General Hospital, Beijing, China
- Department of Immunology, Institute of Basic Medicine, School of Life Sciences, Chinese PLA General Hospital, Beijing, China
| | - Weidong Han
- Department of Molecular Biology, Institute of Basic Medicine, School of Life Sciences, Chinese PLA General Hospital, Beijing, China
- Department of Immunology, Institute of Basic Medicine, School of Life Sciences, Chinese PLA General Hospital, Beijing, China
- * E-mail:
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Wong MV, Palasingam P, Kolatkar PR. Cloning, purification and preliminary X-ray data analysis of the human ID2 homodimer. Acta Crystallogr Sect F Struct Biol Cryst Commun 2012; 68:1354-8. [PMID: 23143248 PMCID: PMC3515380 DOI: 10.1107/s174430911203895x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2012] [Accepted: 09/11/2012] [Indexed: 11/11/2022]
Abstract
The ID proteins are named for their role as inhibitors of DNA binding and differentiation. They contain a helix-loop-helix (HLH) domain but lack a basic DNA-binding domain. In complex with basic HLH (bHLH) transcription factors, gene expression is regulated by DNA-binding inactivation. Although the HLH domain is highly conserved and shares a similar topology, the IDs preferentially bind class I bHLH-group members such as E47 (TCF3) but not the class III bHLH member Myc. A structure of an ID protein could potentially shed light on its mechanism. Owing to their short half-lives in vivo and reported in vitro instability, this paper describes the strategies that went into expressing sufficient soluble and stable ID2 to finally obtain diffraction-quality crystals. A 2.1 Å resolution data set was collected from a crystal belonging to space group P3(1)21 with unit-cell parameters a=b=51.622, c=111.474 Å, α=β=90, γ=120° that was obtained by hanging-drop vapour diffusion in a precipitant solution consisting of 0.1 M MES pH 6.5, 2.0 M potassium acetate. The solvent content was consistent with the presence of one or two molecules in the asymmetric unit.
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Affiliation(s)
- Marie V. Wong
- Laboratory for Structural Biochemistry, Genome Institute of Singapore, Genome, 60 Biopolis Street, Singapore 138672, Singapore
- Department of Biological Sciences, National University of Singapore, 14 Science Drive 4, Singapore 117543, Singapore
| | - Paaventhan Palasingam
- Laboratory for Structural Biochemistry, Genome Institute of Singapore, Genome, 60 Biopolis Street, Singapore 138672, Singapore
| | - Prasanna R. Kolatkar
- Laboratory for Structural Biochemistry, Genome Institute of Singapore, Genome, 60 Biopolis Street, Singapore 138672, Singapore
- Department of Biological Sciences, National University of Singapore, 14 Science Drive 4, Singapore 117543, Singapore
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Abstract
Stress-induced hypertrophic growth of the heart predisposes the heart to arrhythmia, contractile dysfunction, and clinical heart failure. FHL2 (four-and-a-half LIM domain protein 2) is expressed predominantly in the heart, and inactivation of the gene coding for FHL2 leads to exaggerated responsiveness to adrenergic stress. Activation of calcineurin occurs downstream of β-adrenergic signaling and is required for isoproterenol-induced myocardial hypertrophy. Based on these facts, we hypothesized that FHL2 suppresses stress-induced activation of calcineurin. FHL2 is upregulated in mouse hearts exposed to isoproterenol, a β-adrenergic agonist, and isoproterenol-induced increases in the NFAT target genes RCAN1.4 and BNP were amplified significantly in FHL2 knockout (FHL2(-/-)) mice compared with levels in wild-type (WT) mice. To determine whether the effect of FHL2 on NFAT target gene transcript levels occurred at the level of transcription, HEK 293 cells and neonatal rat ventricular myocytes (NRVMs) were transfected with a luciferase reporter construct harboring the NFAT-dependent promoters of either RCAN1 or interleukin 2 (IL-2). Consistent with the in vivo data, small interfering RNA (siRNA) knockdown of FHL2 led to increased activation of these promoters by constitutively active calcineurin or the calcium ionophore ionomycin. Importantly, activation of the RCAN1 promoter by ionomycin, in control and FHL2 knockdown cells, was abolished by the calcineurin inhibitor cyclosporine, confirming the calcineurin dependence of the response. Overexpression of FHL2 inhibited activation of both NFAT reporter constructs. Furthermore, NRVMs overexpressing FHL2 exhibited reduced hypertrophic growth in response to constitutively active calcineurin, as measured by cell cross-sectional area and fetal gene expression. Finally, immunostaining in isolated adult cardiomyocytes revealed colocalization of FHL2 and calcineurin predominantly at the sarcomere and activation of calcineurin by endothelin-1-facilitated interaction between FHL2 and calcineurin. FHL2 is an endogenous, agonist-dependent suppressor of calcineurin.
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Lu Y, Liu X, Shi S, Su H, Bai X, Cai G, Yang F, Xie Z, Zhu Y, Zhang Y, Zhang S, Li X, Wang S, Wu D, Zhang L, Wu J, Xie Y, Chen X. Bioinformatics analysis of proteomic profiles during the process of anti-Thy1 nephritis. Mol Cell Proteomics 2011; 11:M111.008755. [PMID: 22159597 DOI: 10.1074/mcp.m111.008755] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Anti-Thy1 nephritis is a well-established experimental mesangial proliferative nephritis model. Exploring the molecular mechanisms of pathophysiology in anti-Thy1 nephritis may elucidate the pathogeneses of mesangial proliferation. We examined the roles and acting mechanisms of differentially expressed proteins (DEPs) by bioinformatics analysis of glomeruli proteomic profiles during the course of anti-Thy1 nephritis. In total, 108 DEPs were found by two-dimensional fluorescence difference gel electrophoresis (2D-DIGE), and 40 DEPs were identified by matrix-assisted laser desorption ionization/time of flight and liquid chromatography-MS. DEPs were classified into five clusters (Clusters 1-5), according to their expression trends using Cluster 3.0 software, involved in regulating biological processes such as the stress response, cell proliferation, apoptosis, energy metabolism, transport, and the actin cytoskeleton. The expression patterns of ten DEPs, distributed across five clusters, including AKR1A1, AGAT, ATP6V1B2, HIBADH, MDH1, MPST, NIT2, PRDX6, PSMB7, and TPI1, were validated by Western blotting. Based on Western blotting and immunohistochemistry, we also found that the DEP FHL2, which was primarily expressed in the mesangial region, was down-regulated on days 3 and 5, and up-regulated on day 10. In vitro, we found that FHL2 overexpression induced mesangial cell proliferation by increasing the number of S-phase cells and decreasing G2/M-phase cells, whereas inhibiting FHL2 had the opposite effect. This study explored novel DEPs and their expression patterns during anti-Thy1 nephritis, and elucidated FHL2's effect on mesangial cell proliferation. These results will contribute to our understanding of the pathogenesis of mesangial proliferation.
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Affiliation(s)
- Yang Lu
- Department of Nephrology, State Key Lab of Kidney Diseases, General Hospital of PLA, Beijing, China
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Wu Z, Li Y, Li X, Ti D, Zhao Y, Si Y, Mei Q, Zhao P, Fu X, Han W. LRP16 integrates into NF-κB transcriptional complex and is required for its functional activation. PLoS One 2011; 6:e18157. [PMID: 21483817 PMCID: PMC3069058 DOI: 10.1371/journal.pone.0018157] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2010] [Accepted: 02/23/2011] [Indexed: 12/30/2022] Open
Abstract
Background Nuclear factor κB (NF-κB)-mediated pathways have been widely implicated in cell survival, development and tumor progression. Although the molecular events of determining NF-κB translocation from cytoplasm to nucleus have been extensively documented, the regulatory mechanisms of NF-κB activity inside the nucleus are still poorly understood. Being a special member of macro domain proteins, LRP16 was previously identified as a coactivator of both estrogen receptor and androgen receptor, and as an interactor of NF-κB coactivator UXT. Here, we investigated the regulatory role of LRP16 on NF-κB activation. Methodology GST pull-down and coimmunoprecipitation (CoIP) assays assessed protein-protein interactions. The functional activity of NF-κB was assessed by luciferase assays, changes in expression of its target genes, and its DNA binding ability. Annexin V staining and flow cytometry analysis were used to evaluate cell apoptosis. Immunohistochemical staining of LRP16 and enzyme-linked immunosorbent assay-based evaluation of active NF-κB were performed on primary human gastric carcinoma samples. Results We demonstrate that LRP16 integrates into NF-κB transcriptional complex through associating with its p65 component. RNA interference knockdown of the endogenous LRP16 in cells leads to impaired NF-κB activity and significantly attenuated NF-κB-dependent gene expression. Mechanistic analysis revealed that knockdown of LRP16 did not affect tumor necrosis factor α (TNF-α)-induced nuclear translocation of NF-κB, but blunted the formation or stabilization of functional NF-κB/p300/CREB-binding protein transcription complex in the nucleus. In addition, knockdown of LRP16 also sensitizes cells to apoptosis induced by TNF-α. Finally, a positive link between LRP16 expression intensity in nuclei of tumor cells and NF-κB activity was preliminarily established in human gastric carcinoma specimens. Conclusions Our findings not only indicate that LRP16 is a crucial regulator for NF-κB activation inside the nucleus, but also suggest that LRP16 may be an important contributor to the aberrant activation of NF-κB in tumors.
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Affiliation(s)
- Zhiqiang Wu
- Department of Molecular Biology, Institute of Basic Medicine, Chinese PLA General Hospital, Beijing, China
| | - Yazhuo Li
- Department of Pathology, Chinese PLA General Hospital, Beijing, China
| | - Xiaolei Li
- Department of Molecular Biology, Institute of Basic Medicine, Chinese PLA General Hospital, Beijing, China
| | - Dongdong Ti
- Department of Molecular Biology, Institute of Basic Medicine, Chinese PLA General Hospital, Beijing, China
| | - Yali Zhao
- Department of Molecular Biology, Institute of Basic Medicine, Chinese PLA General Hospital, Beijing, China
| | - Yiling Si
- Department of Molecular Biology, Institute of Basic Medicine, Chinese PLA General Hospital, Beijing, China
| | - Qian Mei
- Department of Molecular Biology, Institute of Basic Medicine, Chinese PLA General Hospital, Beijing, China
| | - Po Zhao
- Department of Pathology, Chinese PLA General Hospital, Beijing, China
| | - Xiaobing Fu
- Department of Molecular Biology, Institute of Basic Medicine, Chinese PLA General Hospital, Beijing, China
| | - Weidong Han
- Department of Molecular Biology, Institute of Basic Medicine, Chinese PLA General Hospital, Beijing, China
- * E-mail:
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Han WD, Wu ZQ, Zhao YL, Si YL, Guo MZ, Fu XB. FHL2 antagonizes Id1-promoted proliferation and invasive capacity of human MCF-7 breast cancer cells. Chin J Cancer Res 2010. [DOI: 10.1007/s11670-010-0194-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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Keratin 18 attenuates estrogen receptor alpha-mediated signaling by sequestering LRP16 in cytoplasm. BMC Cell Biol 2009; 10:96. [PMID: 20035625 PMCID: PMC2804594 DOI: 10.1186/1471-2121-10-96] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2009] [Accepted: 12/26/2009] [Indexed: 01/13/2023] Open
Abstract
Background Oncogenesis in breast cancer is often associated with excess estrogen receptor α(ERα) activation and overexpression of its coactivators. LRP16 is both an ERα target gene and an ERα coactivator, and plays a crucial role in ERα activation and proliferation of MCF-7 breast cancer cells. However, the regulation of the functional availability of this coactivator protein is not yet clear. Results Yeast two-hybrid screening, GST pulldown and coimmunoprecipitation (CoIP) identified the cytoplasmic intermediate filament protein keratin 18 (K18) as a novel LRP16-interacting protein. Fluorescence analysis revealed that GFP-tagged LRP16 was primarily localized in the nuclei of mock-transfected MCF-7 cells but was predominantly present in the cytoplasm of K18-transfected cells. Immunoblotting analysis demonstrated that the amount of cytoplasmic LRP16 was markedly increased in cells overexpressing K18 whereas nuclear levels were depressed. Conversely, knockdown of endogenous K18 expression in MCF-7 cells significantly decreased the cytoplasmic levels of LRP16 and increased levels in the nucleus. CoIP failed to detect any interaction between K18 and ERα, but ectopic expression of K18 in MCF-7 cells significantly blunted the association of LRP16 with ERα, attenuated ERα-activated reporter gene activity, and decreased estrogen-stimulated target gene expression by inhibiting ERα recruitment to DNA. Furthermore, BrdU incorporation assays revealed that K18 overexpression blunted the estrogen-stimulated increase of S-phase entry of MCF-7 cells. By contrast, knockdown of K18 in MCF-7 cells significantly increased ERα-mediated signaling and promoted cell cycle progression. Conclusions K18 can effectively associate with and sequester LRP16 in the cytoplasm, thus attenuating the final output of ERα-mediated signaling and estrogen-stimulated cell cycle progression of MCF-7 breast cancer cells. Loss of K18 increases the functional availability of LRP16 to ERα and promotes the proliferation of ERα-positive breast tumor cells. K18 plays an important functional role in regulating the ERα signaling pathway.
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