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Yao Q, Long C, Yi P, Zhang G, Wan W, Rao X, Ying J, Liang W, Hua F. C/EBPβ: A transcription factor associated with the irreversible progression of Alzheimer's disease. CNS Neurosci Ther 2024; 30:e14721. [PMID: 38644578 PMCID: PMC11033503 DOI: 10.1111/cns.14721] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2023] [Revised: 03/20/2024] [Accepted: 03/27/2024] [Indexed: 04/23/2024] Open
Abstract
BACKGROUND Alzheimer's disease (AD) is a neurodegenerative disorder distinguished by a swift cognitive deterioration accompanied by distinctive pathological hallmarks such as extracellular Aβ (β-amyloid) peptides, neuronal neurofibrillary tangles (NFTs), sustained neuroinflammation, and synaptic degeneration. The elevated frequency of AD cases and its proclivity to manifest at a younger age present a pressing challenge in the quest for novel therapeutic interventions. Numerous investigations have substantiated the involvement of C/EBPβ in the progression of AD pathology, thus indicating its potential as a therapeutic target for AD treatment. AIMS Several studies have demonstrated an elevation in the expression level of C/EBPβ among individuals afflicted with AD. Consequently, this review predominantly delves into the association between C/EBPβ expression and the pathological progression of Alzheimer's disease, elucidating its underlying molecular mechanism, and pointing out the possibility that C/EBPβ can be a new therapeutic target for AD. METHODS A systematic literature search was performed across multiple databases, including PubMed, Google Scholar, and so on, utilizing predetermined keywords and MeSH terms, without temporal constraints. The inclusion criteria encompassed diverse study designs, such as experimental, case-control, and cohort studies, restricted to publications in the English language, while conference abstracts and unpublished sources were excluded. RESULTS Overexpression of C/EBPβ exacerbates the pathological features of AD, primarily by promoting neuroinflammation and mediating the transcriptional regulation of key molecular pathways, including δ-secretase, apolipoprotein E4 (APOE4), acidic leucine-rich nuclear phosphoprotein-32A (ANP32A), transient receptor potential channel 1 (TRPC1), and Forkhead BoxO (FOXO). DISCUSSION The correlation between overexpression of C/EBPβ and the pathological development of AD, along with its molecular mechanisms, is evident. Investigating the pathways through which C/EBPβ regulates the development of AD reveals numerous multiple vicious cycle pathways exacerbating the pathological progression of the disease. Furthermore, the exacerbation of pathological progression due to C/EBPβ overexpression and its molecular mechanism is not limited to AD but also extends to other neurodegenerative diseases such as amyotrophic lateral sclerosis (ALS), Parkinson's disease (PD), and multiple sclerosis (MS). CONCLUSION The overexpression of C/EBPβ accelerates the irreversible progression of AD pathophysiology. Additionally, C/EBPβ plays a crucial role in mediating multiple pathways linked to AD pathology, some of which engender vicious cycles, leading to the establishment of feedback mechanisms. To sum up, targeting C/EBPβ could hold promise as a therapeutic strategy not only for AD but also for other degenerative diseases.
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Affiliation(s)
- Qing Yao
- Department of AnesthesiologyThe Second Affiliated Hospital of Nanchang UniversityNanchang CityJiangxi ProvinceChina
- Key Laboratory of Anesthesiology of Jiangxi ProvinceNanchang CityJiangxi ProvinceChina
| | - Chubing Long
- Department of AnesthesiologyThe Second Affiliated Hospital of Nanchang UniversityNanchang CityJiangxi ProvinceChina
- Key Laboratory of Anesthesiology of Jiangxi ProvinceNanchang CityJiangxi ProvinceChina
| | - Pengcheng Yi
- Department of AnesthesiologyThe Second Affiliated Hospital of Nanchang UniversityNanchang CityJiangxi ProvinceChina
- Key Laboratory of Anesthesiology of Jiangxi ProvinceNanchang CityJiangxi ProvinceChina
| | - Guangyong Zhang
- Department of AnesthesiologyThe Second Affiliated Hospital of Nanchang UniversityNanchang CityJiangxi ProvinceChina
- Key Laboratory of Anesthesiology of Jiangxi ProvinceNanchang CityJiangxi ProvinceChina
| | - Wei Wan
- Department of AnesthesiologyThe Second Affiliated Hospital of Nanchang UniversityNanchang CityJiangxi ProvinceChina
- Key Laboratory of Anesthesiology of Jiangxi ProvinceNanchang CityJiangxi ProvinceChina
| | - Xiuqin Rao
- Department of AnesthesiologyThe Second Affiliated Hospital of Nanchang UniversityNanchang CityJiangxi ProvinceChina
- Key Laboratory of Anesthesiology of Jiangxi ProvinceNanchang CityJiangxi ProvinceChina
| | - Jun Ying
- Department of AnesthesiologyThe Second Affiliated Hospital of Nanchang UniversityNanchang CityJiangxi ProvinceChina
- Key Laboratory of Anesthesiology of Jiangxi ProvinceNanchang CityJiangxi ProvinceChina
| | - Weidong Liang
- Department of AnesthesiologyThe First Affiliated Hospital of Gannan Medical UniversityGanzhouJiangxi ProvinceChina
| | - Fuzhou Hua
- Department of AnesthesiologyThe Second Affiliated Hospital of Nanchang UniversityNanchang CityJiangxi ProvinceChina
- Key Laboratory of Anesthesiology of Jiangxi ProvinceNanchang CityJiangxi ProvinceChina
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Hu B, Liu T, Wu Z, Phan SH. P53 regulates CCAAT/Enhancer binding protein β gene expression. Gene 2023; 884:147675. [PMID: 37541559 DOI: 10.1016/j.gene.2023.147675] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2023] [Revised: 07/13/2023] [Accepted: 07/28/2023] [Indexed: 08/06/2023]
Abstract
BACKGROUND The transcription factor CCAAT/enhancer-binding protein β (C/EBPβ) is implicated in diverse processes and diseases. Its two isoforms, namely liver-enriched activator protein (LAP) and liver-enriched inhibitor protein (LIP) are translated from the same mRNA. They share the same C-terminal DNA binding domain except LAP has an extra N-terminal activation domain. Probably due to its higher affinity for its DNA cognate sequences, LIP can inhibit LAP transcriptional activity even at substoichiometric levels. However, the regulatory mechanism of C/EBPβ gene expression and the LAP: LIP ratio is unclear. METHODS In this study, the C/EBPβ promoter sequence was scanned for conserved P53 response element (P53RE), and binding of P53 to the C/EBPβ promoter was tested by Electrophoretic Mobility Shift Assay (EMSA) and chromatin immunoprecipitation assay. P53 over-expression and dominant negative P53 expression plasmids were transfected into rat lung fibroblasts and tested for C/EBPβ gene transcription and expression. Western blot analysis was used to test the regulation of C/EBPβ LAP and LIP isoforms. Constructs containing the LAP 5'untranslated region (5'UTR) or the LIP 5'UTR region were used to test the importance of 5'UTR in the control of C/EBPβ LAP and LIP translation. RESULTS The C/EBPβ promoter sequence was found to contain a conserved P53 response element (P53RE), which binds P53 as demonstrated by Electrophoresis Mobility Shift Assay and chromatin immunoprecipitation assays. P53 over-expression suppressed while dominant negative P53 stimulated C/EBPβ gene transcription and expression. Western blot analysis showed that P53 differentially regulated the translation of the C/EBPβ LAP and LIP isoforms through the regulation of eIF4E and eIF4E-BP1. Further studies with constructs containing the LAP 5'untranslated region (5'UTR) or the LIP 5'UTR region showed that the 5'UTR is important in differential control of C/EBPβ LAP and LIP translation. CONCLUSION Analysis of the effects of P53 on C/EBPβ expression revealed a novel mechanism by which P53 could antagonize the effects of C/EBPβ on its target gene expression. For the first time, P53 is shown to be a repressor of C/EBPβ gene expression at both transcriptional and translational levels, with a differential effect in the magnitude of the effect on LAP vs. LIP isoforms.
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Affiliation(s)
- Biao Hu
- Department of Internal Medicine, University of Michigan Medical School, 1600 Huron Parkway, Ann Arbor, MI 48109 USA
| | - Tianju Liu
- Department of Pathology, University of Michigan Medical School, 109 Zina Pitcher Place, Ann Arbor, MI 48109 USA
| | - Zhe Wu
- Department of Pathology, University of Michigan Medical School, 109 Zina Pitcher Place, Ann Arbor, MI 48109 USA
| | - Sem H Phan
- Department of Pathology, University of Michigan Medical School, 109 Zina Pitcher Place, Ann Arbor, MI 48109 USA.
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Krivtsova O, Makarova A, Lazarevich N. Aberrant expression of alternative isoforms of transcription factors in hepatocellular carcinoma. World J Hepatol 2018; 10:645-661. [PMID: 30386458 PMCID: PMC6206146 DOI: 10.4254/wjh.v10.i10.645] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/20/2018] [Revised: 06/08/2018] [Accepted: 06/28/2018] [Indexed: 02/06/2023] Open
Abstract
Hepatocellular carcinoma (HCC) is one of the most prevalent malignancies worldwide and the second leading cause of death among all cancer types. Deregulation of the networks of tissue-specific transcription factors (TFs) observed in HCC leads to profound changes in the hepatic transcriptional program that facilitates tumor progression. In addition, recent reports suggest that substantial aberrations in the production of TF isoforms occur in HCC. In vitro experiments have identified distinct isoform-specific regulatory functions and related biological effects of liver-specific TFs that are implicated in carcinogenesis, which may be relevant for tumor progression and clinical outcome. This study reviews available data on the expression of isoforms of liver-specific and ubiquitous TFs in the liver and HCC and their effects, including HNF4α, C/EBPs, p73 and TCF7L2, and indicates that assessment of the ratio of isoforms and targeting specific TF variants may be beneficial for the prognosis and treatment of HCC.
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Affiliation(s)
- Olga Krivtsova
- Federal State Budgetary Institution, “N. N. Blokhin Medical Research Center of Oncology” of the Ministry of Health of the Russian Federation, Moscow 115478, Russian
- M. V. Lomonosov Moscow State University, Moscow 119991, Russian
| | - Anna Makarova
- Federal State Budgetary Institution, “N. N. Blokhin Medical Research Center of Oncology” of the Ministry of Health of the Russian Federation, Moscow 115478, Russian
| | - Natalia Lazarevich
- Federal State Budgetary Institution, “N. N. Blokhin Medical Research Center of Oncology” of the Ministry of Health of the Russian Federation, Moscow 115478, Russian
- M. V. Lomonosov Moscow State University, Moscow 119991, Russian
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Yang LH, Wang Y, Qiao S, Wang MJ, Chen F, Zi XY, Li JX, Zhang HB, Yu B, Hu YP. Liver-enriched activator protein 1 as an isoform of CCAAT/enhancer-binding protein beta suppresses stem cell features of hepatocellular carcinoma. Cancer Manag Res 2018; 10:873-885. [PMID: 29731667 PMCID: PMC5927340 DOI: 10.2147/cmar.s160172] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Purpose Liver cancer stem cells (CSCs) are known to be associated with the development, survival, proliferation, metastasis, and recurrence of liver tumors. The aim of this study was to investigate the association of liver-enriched activator protein 1 (LAP1) with hepatocellular carcinoma (HCC) and liver CSCs (LCSCs) and explore the impact of LAP1 on LCSCs. Materials and methods Differences in LAP1 expression in liver cancer tissues versus matched para-tumoral liver tissues and LCSCs versus non-CSCs were analyzed by Western blotting, real-time polymerase chain reaction, immunohistochemistry, and flow cytometry. The effect of LAP1 on liver cancer cells was evaluated by the expression of CSC markers, oncosphere formation, proliferation, migration, and invasion in vitro. Cell cycle distribution and the number of apoptotic cells were analyzed to assess cell cycle and cell apoptosis. Furthermore, a mouse subcutaneous tumor implant model was established to explore the role of LAP1 in the development of HCC in vivo. Finally, the expression of CSC markers in paraffin-embedded sections was evaluated by immunofluorescence. Results LAP1 was weakly expressed in HCC tumors and cell lines and even weaker in LCSCs. LAP1 inhibited the expression of stem cell–associated genes and reduced the abilities of oncosphere formation, proliferation, migration, and invasion in vitro. Cell cycle assay revealed that LAP1 induced G1/G0 arrest. Furthermore, LAP1 decreased subcutaneous tumor-formation ability and the expression of CSC markers and Ki67 in vivo. Conclusion LAP1 suppressed the stem cell features of HCC, indicating that it possessed an antitumor effect in liver cancer, both in vitro and in vivo; therefore, LAP1 may prove to be a potential target in liver CSC-targeted therapy.
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Affiliation(s)
- Li-Hua Yang
- Department of Cell Biology, Center for Stem Cell and Medicine, Second Military Medical University, Shanghai, People's Republic of China.,Department of Cell Biology and Neurobiology, Xuzhou Medical University, Xuzhou, People's Republic of China
| | - Ye Wang
- Department of Cell Biology, Center for Stem Cell and Medicine, Second Military Medical University, Shanghai, People's Republic of China.,Department of Urology, Changhai Hospital, Second Military Medical University, Shanghai, People's Republic of China
| | - Shi Qiao
- Department of Cell Biology, Center for Stem Cell and Medicine, Second Military Medical University, Shanghai, People's Republic of China
| | - Min-Jun Wang
- Department of Cell Biology, Center for Stem Cell and Medicine, Second Military Medical University, Shanghai, People's Republic of China
| | - Fei Chen
- Department of Cell Biology, Center for Stem Cell and Medicine, Second Military Medical University, Shanghai, People's Republic of China
| | - Xiao-Yuan Zi
- Department of Cell Biology, Center for Stem Cell and Medicine, Second Military Medical University, Shanghai, People's Republic of China
| | - Jian-Xiu Li
- Department of Cell Biology, Center for Stem Cell and Medicine, Second Military Medical University, Shanghai, People's Republic of China
| | - Hai-Bin Zhang
- Department of Hepatic Surgery V, Eastern Hepatobiliary Surgery Hospital, Shanghai, People's Republic of China
| | - Bing Yu
- Department of Cell Biology, Center for Stem Cell and Medicine, Second Military Medical University, Shanghai, People's Republic of China.,Department of Hepatic Surgery V, Eastern Hepatobiliary Surgery Hospital, Shanghai, People's Republic of China
| | - Yi-Ping Hu
- Department of Cell Biology, Center for Stem Cell and Medicine, Second Military Medical University, Shanghai, People's Republic of China
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Hansberg-Pastor V, González-Arenas A, Camacho-Arroyo I. CCAAT/enhancer binding protein β negatively regulates progesterone receptor expression in human glioblastoma cells. Mol Cell Endocrinol 2017; 439:317-327. [PMID: 27663075 DOI: 10.1016/j.mce.2016.09.018] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/30/2016] [Revised: 08/29/2016] [Accepted: 09/19/2016] [Indexed: 12/12/2022]
Abstract
Many progesterone (P4) actions are mediated by its intracellular receptor (PR), which has two isoforms (PR-A and PR-B) differentially transcribed from separate promoters of a single gene. In glioblastomas, the most frequent and aggressive brain tumors, PR-B is the predominant isoform. In an in silico analysis we showed putative CCAAT/Enhancer Binding Protein (C/EBP) binding sites at PR-B promoter. We evaluated the role of C/EBPβ in PR-B expression regulation in glioblastoma cell lines, which expressed different ratios of PR and C/EBPβ isoforms (LAP1, LAP2, and LIP). ChIP assays showed a significant basal binding of C/EBPβ, specific protein 1 (Sp1) and estrogen receptor alpha (ERα) to PR-B promoter. C/EBPβ knockdown increased PR-B expression and treatment with estradiol (E2) reduced C/EBPβ binding to the promoter and up-regulated PR-B expression. P4 induced genes were differently regulated when CEBP/β was silenced. These data show that C/EBPβ negatively regulates PR-B expression in glioblastoma cells.
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Affiliation(s)
- Valeria Hansberg-Pastor
- Facultad de Química, Departamento de Biología, Universidad Nacional Autónoma de México (UNAM), Mexico
| | - Aliesha González-Arenas
- Departamento de Medicina Genómica y Toxicología Ambiental, Instituto de Investigaciones Biomédicas, UNAM, Mexico
| | - Ignacio Camacho-Arroyo
- Unidad de Investigación en Reproducción Humana, Instituto Nacional de Perinatología-Facultad de Química, UNAM, Ciudad de México, Mexico.
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Giebel NL, Shadley JD, McCarver DG, Dorko K, Gramignoli R, Strom SC, Yan K, Simpson PM, Hines RN. Role of Chromatin Structural Changes in Regulating Human CYP3A Ontogeny. ACTA ACUST UNITED AC 2016; 44:1027-37. [PMID: 26921389 DOI: 10.1124/dmd.116.069344] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2016] [Accepted: 02/25/2016] [Indexed: 11/22/2022]
Abstract
Variability in drug-metabolizing enzyme developmental trajectories contributes to interindividual differences in susceptibility to chemical toxicity and adverse drug reactions, particularly in the first years of life. Factors linked to these interindividual differences are largely unknown, but molecular mechanisms regulating ontogeny are likely involved. To evaluate chromatin structure dynamics as a likely contributing mechanism, age-dependent changes in modified and variant histone occupancy were evaluated within known CYP3A4 and 3A7 regulatory domains. Chromatin immunoprecipitation using fetal or postnatal human hepatocyte chromatin pools followed by quantitative polymerase chain reaction DNA amplification was used to determine relative chromatin occupancy by modified and variant histones. Chromatin structure representing a poised transcriptional state (bivalent chromatin), indicated by the occupancy by modified histones associated with both active and repressed transcription, was observed for CYP3A4 and most 3A7 regulatory regions in both postnatal and fetal livers. However, the CYP3A4 regulatory regions had significantly greater occupancy by modified histones associated with repressed transcription in the fetal liver. Conversely, some modified histones associated with active transcription exhibited greater occupancy in the postnatal liver. CYP3A7 regulatory regions also had significantly greater occupancy by modified histones associated with repressed transcription in the fetus. The observed occupancy by modified histones is consistent with chromatin structural dynamics contributing to CYP3A4 ontogeny, although the data are less conclusive regarding CYP3A7. Interpretation of the latter data may be confounded by cell-type heterogeneity in the fetal liver.
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Affiliation(s)
- Nicholas L Giebel
- Departments of Pediatrics and Pharmacology and Toxicology, Medical College of Wisconsin, and Children's Research Institute, Children's Hospital and Health Systems, Milwaukee, Wisconsin (N.L.G., J.D.S., D.G.M., K.Y., P.M.S., R.N.H.); and Department of Pathology, University of Pittsburgh, Pittsburgh, Pennsylvania (K.D., R.G., S.C.S.)
| | - Jeffrey D Shadley
- Departments of Pediatrics and Pharmacology and Toxicology, Medical College of Wisconsin, and Children's Research Institute, Children's Hospital and Health Systems, Milwaukee, Wisconsin (N.L.G., J.D.S., D.G.M., K.Y., P.M.S., R.N.H.); and Department of Pathology, University of Pittsburgh, Pittsburgh, Pennsylvania (K.D., R.G., S.C.S.)
| | - D Gail McCarver
- Departments of Pediatrics and Pharmacology and Toxicology, Medical College of Wisconsin, and Children's Research Institute, Children's Hospital and Health Systems, Milwaukee, Wisconsin (N.L.G., J.D.S., D.G.M., K.Y., P.M.S., R.N.H.); and Department of Pathology, University of Pittsburgh, Pittsburgh, Pennsylvania (K.D., R.G., S.C.S.)
| | - Kenneth Dorko
- Departments of Pediatrics and Pharmacology and Toxicology, Medical College of Wisconsin, and Children's Research Institute, Children's Hospital and Health Systems, Milwaukee, Wisconsin (N.L.G., J.D.S., D.G.M., K.Y., P.M.S., R.N.H.); and Department of Pathology, University of Pittsburgh, Pittsburgh, Pennsylvania (K.D., R.G., S.C.S.)
| | - Roberto Gramignoli
- Departments of Pediatrics and Pharmacology and Toxicology, Medical College of Wisconsin, and Children's Research Institute, Children's Hospital and Health Systems, Milwaukee, Wisconsin (N.L.G., J.D.S., D.G.M., K.Y., P.M.S., R.N.H.); and Department of Pathology, University of Pittsburgh, Pittsburgh, Pennsylvania (K.D., R.G., S.C.S.)
| | - Stephen C Strom
- Departments of Pediatrics and Pharmacology and Toxicology, Medical College of Wisconsin, and Children's Research Institute, Children's Hospital and Health Systems, Milwaukee, Wisconsin (N.L.G., J.D.S., D.G.M., K.Y., P.M.S., R.N.H.); and Department of Pathology, University of Pittsburgh, Pittsburgh, Pennsylvania (K.D., R.G., S.C.S.)
| | - Ke Yan
- Departments of Pediatrics and Pharmacology and Toxicology, Medical College of Wisconsin, and Children's Research Institute, Children's Hospital and Health Systems, Milwaukee, Wisconsin (N.L.G., J.D.S., D.G.M., K.Y., P.M.S., R.N.H.); and Department of Pathology, University of Pittsburgh, Pittsburgh, Pennsylvania (K.D., R.G., S.C.S.)
| | - Pippa M Simpson
- Departments of Pediatrics and Pharmacology and Toxicology, Medical College of Wisconsin, and Children's Research Institute, Children's Hospital and Health Systems, Milwaukee, Wisconsin (N.L.G., J.D.S., D.G.M., K.Y., P.M.S., R.N.H.); and Department of Pathology, University of Pittsburgh, Pittsburgh, Pennsylvania (K.D., R.G., S.C.S.)
| | - Ronald N Hines
- Departments of Pediatrics and Pharmacology and Toxicology, Medical College of Wisconsin, and Children's Research Institute, Children's Hospital and Health Systems, Milwaukee, Wisconsin (N.L.G., J.D.S., D.G.M., K.Y., P.M.S., R.N.H.); and Department of Pathology, University of Pittsburgh, Pittsburgh, Pennsylvania (K.D., R.G., S.C.S.)
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Riganti C, Kopecka J, Panada E, Barak S, Rubinstein M. The role of C/EBP-β LIP in multidrug resistance. J Natl Cancer Inst 2015; 107:djv046. [PMID: 25766403 DOI: 10.1093/jnci/djv046] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
BACKGROUND Chemotherapy triggers endoplasmic reticulum (ER) stress, which in turn regulates levels of the active (LAP) and the natural dominant-negative (LIP) forms of the transcription factor C/EBP-β. LAP upregulates and LIP downregulates the multidrug resistance (MDR) protein P-glycoprotein (Pgp), but it is not known how critical is their role in establishing MDR. METHODS Cell viability was quantitated by crystal violet staining and measuring absorbance at 540nm. Expression of various proteins was determined by immunoblotting. mRNA levels were determined by quantitative reverse transcriptase polymerase chain reaction (RT-PCR). LIP and LAP were overexpressed using expression plasmids followed by selection with blasticidin. Tumor cells expressing doxycycline-inducible LIP were orthotopically implanted in mice (n = 15 mice per group), and tumor size was measured daily by caliper. Tumor sections were stained with hematoxylin and eosin and immunostained for Pgp, proliferation, and ER stress markers. RESULTS MDR cells do not express basal, chemotherapy-triggered, or ER stress-triggered LIP and fail to activate the CHOP-caspase-3 death-triggering axis upon ER stress or chemotherapy challenge. Overexpression of LIP reversed the MDR phenotype in vitro and in tumors implanted in mice. LIP was undetectable in MDR cells, probably due to its ubiquitination, which was 3.56-fold higher, resulting in lysosomal and proteasomal degradation of LIP. CONCLUSIONS Spontaneous and drug-selected MDR cells lack LIP, which is eliminated by ubiquitin-mediated degradation. Loss of LIP drives MDR not only by increasing Pgp expression but also by a two-fold attenuation of ER stress-triggered cell death.
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Affiliation(s)
- Chiara Riganti
- Department of Oncology, University of Torino, Italy (CR, JK, EP); Department of Molecular Genetics, the Weizmann Institute of Science, Rehovot, Israel (SB, MR)
| | - Joanna Kopecka
- Department of Oncology, University of Torino, Italy (CR, JK, EP); Department of Molecular Genetics, the Weizmann Institute of Science, Rehovot, Israel (SB, MR)
| | - Elisa Panada
- Department of Oncology, University of Torino, Italy (CR, JK, EP); Department of Molecular Genetics, the Weizmann Institute of Science, Rehovot, Israel (SB, MR)
| | - Sara Barak
- Department of Oncology, University of Torino, Italy (CR, JK, EP); Department of Molecular Genetics, the Weizmann Institute of Science, Rehovot, Israel (SB, MR)
| | - Menachem Rubinstein
- Department of Oncology, University of Torino, Italy (CR, JK, EP); Department of Molecular Genetics, the Weizmann Institute of Science, Rehovot, Israel (SB, MR).
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Dupuis L, Schuermann Y, Cohen T, Siddappa D, Kalaiselvanraja A, Pansera M, Bordignon V, Duggavathi R. Role of leptin receptors in granulosa cells during ovulation. Reproduction 2014; 147:221-9. [DOI: 10.1530/rep-13-0356] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Leptin is an important hormone influencing reproductive function. However, the mechanisms underpinning the role of leptin in the regulation of reproduction remain to be completely deciphered. In this study, our objective is to understand the mechanisms regulating the expression of leptin receptor (Lepr) and its role in ovarian granulosa cells during ovulation. First, granulosa cells were collected from superovulated mice to profile mRNA expression of Lepr isoforms (LeprA and LeprB) throughout follicular development. Expression of LeprA and LeprB was dramatically induced in the granulosa cells of ovulating follicles at 4 h after human chorionic gonadotropin (hCG) treatment. Relative abundance of both mRNA and protein of CCAAT/enhancer-binding protein β (Cebpβ) increased in granulosa cells from 1 to 7 h post-hCG. Furthermore, chromatin immunoprecipitation assay confirmed the recruitment of Cebpβ to Lepr promoter. Thus, hCG-induced transcription of Lepr appears to be regulated by Cebpβ, which led us to hypothesise that Lepr may play a role during ovulation. To test this hypothesis, we used a recently developed pegylated superactive mouse leptin antagonist (PEG-SMLA) to inhibit Lepr signalling during ovulation. I.p. administration of PEG-SMLA (10 μg/g) to superovulated mice reduced ovulation rate by 65% compared with control treatment. Although the maturation stage of the ovulated oocytes remained unaltered, ovulation genes Ptgs2 and Has2 were downregulated in PEG-SMLA-treated mice compared with control mice. These results demonstrate that Lepr is dramatically induced in the granulosa cells of ovulating follicles and this induction of Lepr expression requires the transcription factor Cebpβ. Lepr plays a critical role in the process of ovulation by regulating, at least in part, the expression of the important genes involved in the preovulatory maturation of follicles.
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Oncogenic KRAS impairs EGFR antibodies' efficiency by C/EBPβ-dependent suppression of EGFR expression. Neoplasia 2012; 14:190-205. [PMID: 22496619 DOI: 10.1593/neo.111636] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2011] [Revised: 02/17/2012] [Accepted: 02/20/2012] [Indexed: 12/29/2022] Open
Abstract
Oncogenic KRAS mutations in colorectal cancer (CRC) are associated with lack of benefit from epidermal growth factor receptor (EGFR)-directed antibody (Ab) therapy. However, the mechanisms by which constitutively activated KRAS (KRAS(G12V)) impairs effector mechanisms of EGFR-Abs are incompletely understood. Here, we established isogenic cell line models to systematically investigate the impact of KRAS(G12V) on tumor growth in mouse A431 xenograft models as well as on various modes of action triggered by EGFR-Abs in vitro. KRAS(G12V) impaired EGFR-Ab-mediated growth inhibition by stimulating receptor-independent downstream signaling. KRAS(G12V) also rendered tumor cells less responsive to Fc-mediated effector mechanisms of EGFR-Abs-such as complement-dependent cytotoxicity (CDC) and Ab-dependent cell-mediated cytotoxicity (ADCC). Impaired CDC and ADCC activities could be linked to reduced EGFR expression in KRAS-mutated versus wild-type (wt) cells, which was restored by small interfering RNA (siRNA)-mediated knockdown of KRAS4b. Immunohistochemistry experiments also revealed lower EGFR expression in KRAS-mutated versus KRAS-wt harboring CRC samples. Analyses of potential mechanisms by which KRAS(G12V) downregulated EGFR expression demonstrated significantly decreased activity of six distinct transcription factors. Additional experiments suggested the CCAAT/enhancer-binding protein (C/EBP) family to be implicated in the regulation of EGFR promoter activity in KRAS-mutated tumor cells by suppressing EGFR transcription through up-regulation of the inhibitory family member C/EBPβ-LIP. Thus, siRNA-mediated knockdown of C/EBPβ led to enhanced EGFR expression and Ab-mediated cytotoxicity against KRAS-mutated cells. Together, these results demonstrate that KRAS(G12V) signaling induced C/EBPβ-dependent suppression of EGFR expression, thereby impairing Fc-mediated effector mechanisms of EGFR-Abs and rendering KRAS-mutated tumor cells less sensitive to these therapeutic agents.
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