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Omori K, Otani S, Date Y, Ueno T, Ito T, Umeda M, Ito K. C/ebpα represses the oncogenic Runx3-Myc axis in p53-deficient osteosarcoma development. Oncogene 2023; 42:2485-2494. [PMID: 37402881 DOI: 10.1038/s41388-023-02761-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2022] [Revised: 06/14/2023] [Accepted: 06/22/2023] [Indexed: 07/06/2023]
Abstract
Osteosarcoma (OS) is characterized by TP53 mutations in humans. In mice, loss of p53 triggers OS development, and osteoprogenitor-specific p53-deleted mice are widely used to study the process of osteosarcomagenesis. However, the molecular mechanisms underlying the initiation or progression of OS following or parallel to p53 inactivation remain largely unknown. Here, we examined the role of transcription factors involved in adipogenesis (adipo-TFs) in p53-deficient OS and identified a novel tumor suppressive molecular mechanism mediated by C/ebpα. C/ebpα specifically interacts with Runx3, a p53 deficiency-dependent oncogene, and, in the same manner as p53, decreases the activity of the oncogenic axis of OS, Runx3-Myc, by inhibiting Runx3 DNA binding. The identification of a novel molecular role for C/ebpα in p53-deficient osteosarcomagenesis underscores the importance of the Runx-Myc oncogenic axis as a therapeutic target for OS.
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Affiliation(s)
- Keisuke Omori
- Department of Molecular Bone Biology, Graduate School of Biomedical Sciences, Nagasaki University, 1-7-1 Sakamoto, Nagasaki, 852-8588, Japan
- Department of Clinical Oral Oncology, Graduate School of Biomedical Sciences, Nagasaki University, 1-7-1 Sakamoto, Nagasaki, 852-8588, Japan
| | - Shohei Otani
- Department of Molecular Bone Biology, Graduate School of Biomedical Sciences, Nagasaki University, 1-7-1 Sakamoto, Nagasaki, 852-8588, Japan
| | - Yuki Date
- Department of Molecular Bone Biology, Graduate School of Biomedical Sciences, Nagasaki University, 1-7-1 Sakamoto, Nagasaki, 852-8588, Japan
| | - Tomoya Ueno
- Department of Molecular Bone Biology, Graduate School of Biomedical Sciences, Nagasaki University, 1-7-1 Sakamoto, Nagasaki, 852-8588, Japan
| | - Tomoko Ito
- Department of Molecular Bone Biology, Graduate School of Biomedical Sciences, Nagasaki University, 1-7-1 Sakamoto, Nagasaki, 852-8588, Japan
| | - Masahiro Umeda
- Department of Clinical Oral Oncology, Graduate School of Biomedical Sciences, Nagasaki University, 1-7-1 Sakamoto, Nagasaki, 852-8588, Japan
| | - Kosei Ito
- Department of Molecular Bone Biology, Graduate School of Biomedical Sciences, Nagasaki University, 1-7-1 Sakamoto, Nagasaki, 852-8588, Japan.
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2
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Sung Y, Yu YC, Han JM. Nutrient sensors and their crosstalk. Exp Mol Med 2023; 55:1076-1089. [PMID: 37258576 PMCID: PMC10318010 DOI: 10.1038/s12276-023-01006-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2022] [Revised: 02/22/2023] [Accepted: 03/13/2023] [Indexed: 06/02/2023] Open
Abstract
The macronutrients glucose, lipids, and amino acids are the major components that maintain life. The ability of cells to sense and respond to fluctuations in these nutrients is a crucial feature for survival. Nutrient-sensing pathways are thus developed to govern cellular energy and metabolic homeostasis and regulate diverse biological processes. Accordingly, perturbations in these sensing pathways are associated with a wide variety of pathologies, especially metabolic diseases. Molecular sensors are the core within these sensing pathways and have a certain degree of specificity and affinity to sense the intracellular fluctuation of each nutrient either by directly binding to that nutrient or indirectly binding to its surrogate molecules. Once the changes in nutrient levels are detected, sensors trigger signaling cascades to fine-tune cellular processes for energy and metabolic homeostasis, for example, by controlling uptake, de novo synthesis or catabolism of that nutrient. In this review, we summarize the major discoveries on nutrient-sensing pathways and explain how those sensors associated with each pathway respond to intracellular nutrient availability and how these mechanisms control metabolic processes. Later, we further discuss the crosstalk between these sensing pathways for each nutrient, which are intertwined to regulate overall intracellular nutrient/metabolic homeostasis.
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Affiliation(s)
- Yulseung Sung
- Yonsei Institute of Pharmaceutical Sciences, College of Pharmacy, Yonsei University, Incheon, 21983, South Korea
| | - Ya Chun Yu
- Yonsei Institute of Pharmaceutical Sciences, College of Pharmacy, Yonsei University, Incheon, 21983, South Korea
| | - Jung Min Han
- Yonsei Institute of Pharmaceutical Sciences, College of Pharmacy, Yonsei University, Incheon, 21983, South Korea.
- Department of Integrated OMICS for Biomedical Science, Yonsei University, Seoul, 03722, South Korea.
- POSTECH Biotech Center, Pohang University of Science and Technology, Pohang, 37673, South Korea.
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Yu YC, Han JM, Kim S. Aminoacyl-tRNA synthetases and amino acid signaling. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2020; 1868:118889. [PMID: 33091505 DOI: 10.1016/j.bbamcr.2020.118889] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Revised: 10/05/2020] [Accepted: 10/10/2020] [Indexed: 12/13/2022]
Abstract
Aminoacyl-tRNA synthetases (ARSs) are a family of evolutionarily conserved housekeeping enzymes used for protein synthesis that have pivotal roles in the ligation of tRNA with their cognate amino acids. Recent advances in the structural and functional studies of ARSs have revealed many previously unknown biological functions beyond the classical catalytic roles. Sensing the sufficiency of intracellular nutrients such as amino acids, ATP, and fatty acids is a crucial aspect for every living organism, and it is closely connected to the regulation of diverse cellular physiologies. Notably, among ARSs, leucyl-tRNA synthetase 1 (LARS1) has been identified to perform specifically as a leucine sensor upstream of the amino acid-sensing pathway and thus participates in the coordinated control of protein synthesis and autophagy for cell growth. In addition to LARS1, other types of ARSs are also likely involved in the sensing and signaling of their cognate amino acids inside cells. Collectively, this review focuses on the mechanisms of ARSs interacting within amino acid signaling and proposes the possible role of ARSs as general intracellular amino acid sensors.
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Affiliation(s)
- Ya Chun Yu
- Yonsei Institute of Pharmaceutical Sciences, College of Pharmacy, Yonsei University, Incheon 21983, South Korea
| | - Jung Min Han
- Yonsei Institute of Pharmaceutical Sciences, College of Pharmacy, Yonsei University, Incheon 21983, South Korea; Department of Integrated OMICS for Biomedical Science, Yonsei University, Seoul 03722, South Korea.
| | - Sunghoon Kim
- Yonsei Institute of Pharmaceutical Sciences, College of Pharmacy, Yonsei University, Incheon 21983, South Korea; Medicinal Bioconvergence Research Center, College of Pharmacy and College of Medicine, Gangnam Severance Hospital, Yonsei University, South Korea.
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Li J, Zhou Y, Yan Y, Zheng Z, Hu Y, Wu W. Sulforaphane-cysteine downregulates CDK4 /CDK6 and inhibits tubulin polymerization contributing to cell cycle arrest and apoptosis in human glioblastoma cells. Aging (Albany NY) 2020; 12:16837-16851. [PMID: 32860670 PMCID: PMC7521484 DOI: 10.18632/aging.103537] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2019] [Accepted: 04/27/2020] [Indexed: 01/24/2023]
Abstract
Here we demonstrated that sulforaphane-cysteine (SFN-Cys) regulated cell cycle-related protein expressions in G0/G1 and G2/M phases of U87MG cells via High Performance Liquid Chromatography-Mass Spectrometry/Mass Spectrometry (HPLC-MS/MS) and proteomics analysis. Further, mRNA products of CDK4, CDK6 and α-tubulin were significantly higher in glioblastoma than those in normal tissues, and these results were significantly correlated to pathological grades and clinical prognosis via analyzing TCGA and CGGA databases. Furthermore, Western blot showed that SFN-Cys downregulated CDK4, CDK6 and p-Rb in a dose-dependent manner and these results were reversed by p-ERK1/2 blocker PD98059 in U87MG and U373MG cells. The reductions of CDK4, CDK6 and p-Rb were reversed by proteasome inhibitor MG132; similarly, the upregulation of 26S proteasome by SFN-Cys was reversed by PD98059. Interestingly, SFN-Cys decreased CDK4 and CDK6 by phosphorylated ERK1/2-caused proteasomal degradation resulting in decreased Rb phosphorylation contributing to cell cycle arrest in G0/G1 phase. Besides, Western blot showed that SFN-Cys downregulated α-tubulin resulting in microtubule disruption and aggregation, and cell cycle arrest in G2/M phase and apoptosis. These results might help us understand the molecular etiology of glioblastoma progression to establish brand-new anti-cancer therapies.
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Affiliation(s)
- Juntao Li
- Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Capital Medical University, Beijing, China,Beijing Key Laboratory for Tumor Invasion and Metastasis, Capital Medical University, Beijing, China
| | - Yan Zhou
- Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Capital Medical University, Beijing, China,Beijing Key Laboratory for Tumor Invasion and Metastasis, Capital Medical University, Beijing, China
| | - Yuting Yan
- Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Capital Medical University, Beijing, China,Beijing Key Laboratory for Tumor Invasion and Metastasis, Capital Medical University, Beijing, China
| | - Zhongnan Zheng
- Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Capital Medical University, Beijing, China,Beijing Key Laboratory for Tumor Invasion and Metastasis, Capital Medical University, Beijing, China
| | - Yabin Hu
- Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Capital Medical University, Beijing, China,Beijing Key Laboratory for Tumor Invasion and Metastasis, Capital Medical University, Beijing, China
| | - Wei Wu
- Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Capital Medical University, Beijing, China,Beijing Key Laboratory for Tumor Invasion and Metastasis, Capital Medical University, Beijing, China
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Keratin 19 regulates cell cycle pathway and sensitivity of breast cancer cells to CDK inhibitors. Sci Rep 2019; 9:14650. [PMID: 31601969 PMCID: PMC6787034 DOI: 10.1038/s41598-019-51195-9] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2019] [Accepted: 09/20/2019] [Indexed: 01/05/2023] Open
Abstract
Keratin 19 (K19) belongs to the keratin family of proteins, which maintains structural integrity of epithelia. In cancer, K19 is highly expressed in several types where it serves as a diagnostic marker. Despite the positive correlation between higher expression of K19 in tumor and worse patient survival, the role of K19 in breast cancer remains unclear. Therefore, we ablated K19 expression in MCF7 breast cancer cells and found that K19 was required for cell proliferation. Transcriptome analyses of KRT19 knockout cells identified defects in cell cycle progression and levels of target genes of E2F1, a key transcriptional factor for the transition into S phase. Furthermore, proper levels of cyclin dependent kinases (CDKs) and cyclins, including D-type cyclins critical for E2F1 activation, were dependent on K19 expression, and K19-cyclin D co-expression was observed in human breast cancer tissues. Importantly, K19 interacts with cyclin D3, and a loss of K19 resulted in decreased protein stability of cyclin D3 and sensitivity of cells towards CDK inhibitor-induced cell death. Overall, these findings reveal a novel function of K19 in the regulation of cell cycle program and suggest that K19 may be used to predict the efficacy of CDK inhibitors for treatments of breast cancer.
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Pibiri M. Liver regeneration in aged mice: new insights. Aging (Albany NY) 2019; 10:1801-1824. [PMID: 30157472 PMCID: PMC6128415 DOI: 10.18632/aging.101524] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2018] [Accepted: 08/10/2018] [Indexed: 02/06/2023]
Abstract
The regenerative capacity of the liver after resection is reduced with aging. Recent studies on rodents revealed that both intracellular and extracellular factors are involved in the impairment of liver mass recovery during aging. Among the intracellular factors, age-dependent decrease of BubR1 (budding uninhibited by benzimidazole-related 1), YAP (Yes-associated protein) and SIRT1 (Sirtuin-1) have been associated to dampening of tissue reconstitution and inhibition of cell cycle genes following partial hepatectomy. Extra-cellular factors, such as age-dependent changes in hepatic stellate cells affect liver regeneration through inhibition of progenitor cells and reduction of liver perfusion. Furthermore, chronic release of pro-inflammatory proteins by senescent cells (SASP) affects cell proliferation suggesting that senescent cell clearance might improve tissue regeneration. Accordingly, young plasma restores liver regeneration in aged animals through autophagy re-establishment. This review will discuss how intracellular and extracellular factors cooperate to guarantee a proper liver regeneration and the possible causes of its impairment during aging. The possibility that an improvement of the liver regenerative capacity in elderly might be achieved through elimination of senescent cells via autophagy or by administration of direct mitogenic agents devoid of cytotoxicity will also be entertained.
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Affiliation(s)
- Monica Pibiri
- Department of Biomedical Sciences, Oncology and Molecular Pathology Unit, University of Cagliari, Cagliari 09124, Italy
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Non-canonical roles of PFKFB3 in regulation of cell cycle through binding to CDK4. Oncogene 2018; 37:1685-1698. [PMID: 29335521 DOI: 10.1038/s41388-017-0072-4] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2017] [Revised: 10/16/2017] [Accepted: 11/08/2017] [Indexed: 01/06/2023]
Abstract
There is growing interest in studying the molecular mechanisms of crosstalk between cancer metabolism and the cell cycle. 6-phosphate fructose-2-kinase/fructose-2,6-bisphosphatase-3 (PFKFB3) is a well-known glycolytic activator that plays an important role in tumorigenesis. We investigated whether PFKFB3 was directly involved in oncogenic signaling networks. Mass Spectrometry showed that PFKFB3 interacts with cyclin-dependent kinase (CDK) 4, which controls the transition from G1 phase to S phase of the cell cycle. Further analysis indicated that lysine 147 was a key site for the binding of PFKBFB3 to CDK4. PFKFB3 binding resulted in the accumulation of CDK4 protein by inhibiting ubiquitin proteasome degradation mediated by the heat shock protein 90-Cdc37-CDK4 complex. The proteasome-dependent degradation of CDK4 was accelerated by disrupting the interaction of PFKFB3 with CDK4 by mutating lysine (147) to alanine. Blocking PFKFB3-CDK4 interaction improved the therapeutic effect of FDA-approved CDK4 inhibitor palbociclib on breast cancer. These findings suggest that PFKFB3 is a hub for coordinating cell cycle and glucose metabolism. Combined targeting of PFKFB3 and CDK4 may be new strategy for breast cancer treatment.
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Song HM, Park GH, Park SB, Kim HS, Son HJ, Um Y, Jeong JB. Vitex rotundifolia Fruit Suppresses the Proliferation of Human Colorectal Cancer Cells through Down-regulation of Cyclin D1 and CDK4 via Proteasomal-Dependent Degradation and Transcriptional Inhibition. THE AMERICAN JOURNAL OF CHINESE MEDICINE 2018; 46:191-207. [PMID: 29298515 DOI: 10.1142/s0192415x18500118] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Viticis Fructus (VF) as the dried fruit from Vitex rotundifolia L. used as a traditional medicine for treating inflammation, headache, migraine, chronic bronchitis, eye pain, and gastrointestinal infections has been reported to have antiproliferative effects against various cancer cells, including breast, lung and colorectal cancer cells. However, the molecular mechanisms by which VF mediates the inhibitory effect of the proliferation of cancer cells have not been elucidated in detail. In this study, we investigated the molecular mechanism of VF on the down-regulation of cyclin D1 and CDK4 level associated with cancer cell proliferation. VF suppressed the proliferation of human colorectal cancer cell lines such as HCT116 and SW480. VF induced decrease in cyclin D1 and CDK4 in both protein and mRNA levels. However, the protein levels of cyclin D1 and CDK4 were decreased by VF at an earlier time than the change of mRNA levels; rather it suppressed the expression of cyclin D1 and CDK4 via the proteasomal degradation. In cyclin D1 and CDK4 degradation, we found that Thr286 phosphorylation of cyclin D1 plays a pivotal role in VF-mediated cyclin D1 degradation. Subsequent experiments with several kinase inhibitors suggest that VF-mediated degradation of cyclin D1 may be dependent on GSK3[Formula: see text] and VF-mediated degradation of CDK4 is dependent on ERK1/2, p38 and GSK3[Formula: see text]. In the transcriptional regulation of cyclin D1 and CDK4, we found that VF inhibited Wnt activation associated with cyclin D1 transcriptional regulation through TCF4 down-regulation. In addition, VF treatment down-regulated c-myc expression associated CDK4 transcriptional regulation. Our results suggest that VF has potential to be a candidate for the development of chemoprevention or therapeutic agents for human colorectal cancer.
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Affiliation(s)
- Hun Min Song
- * Department of Medicinal Plant Resources, Andong National University, Andong 36729, Republic of Korea
| | - Gwang Hun Park
- ‡ Forest Medicinal Resources Research Center, National Institute of Forest Science, Yeongju 36040, Republic of Korea
| | - Su Bin Park
- * Department of Medicinal Plant Resources, Andong National University, Andong 36729, Republic of Korea
| | - Hyun-Seok Kim
- § Department of Food Science & Biotechnology, Kyonggi University, Suwon 16227, Republic of Korea
| | - Ho-Jun Son
- ‡ Forest Medicinal Resources Research Center, National Institute of Forest Science, Yeongju 36040, Republic of Korea
| | - Yurry Um
- ‡ Forest Medicinal Resources Research Center, National Institute of Forest Science, Yeongju 36040, Republic of Korea
| | - Jin Boo Jeong
- * Department of Medicinal Plant Resources, Andong National University, Andong 36729, Republic of Korea.,† Insititute of Agricultural Science and Technology, Andong National University, Andong 36729, Republic of Korea
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Wang L, Zhang R, You X, Zhang H, Wei S, Cheng T, Cao Q, Wang Z, Chen Y. The steady-state level of CDK4 protein is regulated by antagonistic actions between PAQR4 and SKP2 and involved in tumorigenesis. J Mol Cell Biol 2017; 9:409-421. [DOI: 10.1093/jmcb/mjx028] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2017] [Accepted: 08/04/2017] [Indexed: 01/26/2023] Open
Affiliation(s)
- Lin Wang
- CAS Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Rui Zhang
- Cancer Molecular Diagnostic Core Laboratory, Tianjin Medical University Cancer Institute and Hospital, National Clinical Research Center for Cancer, Tianjin Key Laboratory of Cancer Immunology and Biotherapy, Tianjin, China
| | - Xue You
- School of Life Sciences and Technology, ShanghaiTech University, Shanghai, China
| | - Huanhuan Zhang
- School of Life Sciences and Technology, ShanghaiTech University, Shanghai, China
| | - Siying Wei
- CAS Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Tingting Cheng
- Department of Clinical Medicine, Tongji University, Shanghai, China
| | - Qianqian Cao
- CAS Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Zhenzhen Wang
- CAS Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Yan Chen
- CAS Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, China
- School of Life Sciences and Technology, ShanghaiTech University, Shanghai, China
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Du Y, Wu J, Zhang H, Li S, Sun H. Reduced expression of SIRT2 in serous ovarian carcinoma promotes cell proliferation through disinhibition of CDK4 expression. Mol Med Rep 2017; 15:1638-1646. [PMID: 28259910 PMCID: PMC5365020 DOI: 10.3892/mmr.2017.6183] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2015] [Accepted: 12/01/2016] [Indexed: 12/02/2022] Open
Abstract
The silent information regulator 2 related enzyme 2 (SIRT2) has been reported to have an important role in tumorigenesis. Although two distinct effects of SIRT2 have recently been revealed, which explain opposing expression patterns in different types of cancer, the specific function of SIRT2 in ovarian cancer remains unknown. The present study investigated the expression of SIRT2 in serous ovarian carcinoma (SOC) and its pathogenic mechanism. It was observed that SIRT2 expression in SOC was significantly downregulated when compared with ovarian surface epithelium via western blot and immunohistochemistry. Statistical analysis revealed that attenuated expression of SIRT2 was associated with the International Federation of Gynecology and Obstetrics classification of ovarian cancer. Reduced SIRT2 expression during tumorigenesis failed to repress cyclin-dependent kinase 4 expression, which eventually led to accelerated cell proliferation. Furthermore, the wound healing assay and Transwell assay determined that reduced expression of SIRT2 promoted SOC cell migration and invasion. In conclusion, the results of the current study suggest that SIRT2 has a tumor-suppressor function in ovarian cells and it might be a viable target for further SOC treatment.
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Affiliation(s)
- Yanhua Du
- Department of Gynecology, Obstetrics and Gynecology Hospital of Fudan University, P.R. China
| | - Jun Wu
- Pathology Center, Shanghai General Hospital/Faculty of Basic Medicine, Shanghai Jiaotong University School of Medicine, Shanghai 200025, P.R. China
| | - Haiyan Zhang
- Department of Gynecology, Obstetrics and Gynecology Hospital of Fudan University, P.R. China
| | - Shaobo Li
- Pathology Center, Shanghai General Hospital/Faculty of Basic Medicine, Shanghai Jiaotong University School of Medicine, Shanghai 200025, P.R. China
| | - Hong Sun
- Department of Gynecology, Obstetrics and Gynecology Hospital of Fudan University, P.R. China
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Park GH, Sung JH, Song HM, Jeong JB. Anti-cancer activity of Psoralea fructus through the downregulation of cyclin D1 and CDK4 in human colorectal cancer cells. BMC COMPLEMENTARY AND ALTERNATIVE MEDICINE 2016; 16:373. [PMID: 27670681 PMCID: PMC5037586 DOI: 10.1186/s12906-016-1364-x] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/08/2016] [Accepted: 09/09/2016] [Indexed: 11/10/2022]
Abstract
BACKGROUND Psoralea Fructus (PF), the dried and ripe fruit of Psoralea corylifolia exhibits an anti-cancer activity. However, the molecular mechanisms by which PF inhibits the proliferation of cancer cells have not been elucidated in detail. Cyclin D1 and CDK4 are important regulatory proteins in cell growth and are overexpressed in many cancer cells. In this study, we investigated the molecular mechanism of PF on the downregulation of cyclin D1 and CDK4 level. METHODS Cell growth was evaluated by MTT assay. The effect of PF on cyclin D1 and CDK4 expression was evaluated by Western blot or RT-PCR. RESULTS PF suppressed the proliferation of human colorectal cancer cell lines such as HCT116 (IC50: 45.3 ± 1.2 μg/ml), SW480 (IC50: 37.9 ± 1.6 μg/ml), LoVo (IC50: 23.3 ± 1.9 μg/ml μg/ml) HT-29 (IC50 value: 40.7 ± 1.5 μg/ml). PF induced decrease in the protein expression of cyclin D1 and CDK4. However, the mRNA expression of cyclin D1 and CDK4 did not be changed by PF; rather it suppressed the expression of cyclin D1 and CDK4 via the proteasomal degradation. In cyclin D1 degradation, we found that T286 of cyclin D1 play a pivotal role in PF-mediated cyclin D1 degradation. Subsequent experiments with several kinase inhibitors suggest that PF-mediated degradation of cyclin D1 and CDK4 is dependent on ERK1/2 and/or GSK3β. CONCLUSIONS Our results suggest that PF has potential to be a candidate for the development of chemoprevention or therapeutic agents for human colorectal cancer.
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12
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Khan MSS, Majid AMSA, Iqbal MA, Majid ASA, Al-Mansoub M, Haque RSMA. Designing the angiogenic inhibitor for brain tumor via disruption of VEGF and IL17A expression. Eur J Pharm Sci 2016; 93:304-18. [PMID: 27552907 DOI: 10.1016/j.ejps.2016.08.032] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2016] [Revised: 07/30/2016] [Accepted: 08/18/2016] [Indexed: 02/08/2023]
Abstract
Glioblastoma multiforme is a highly malignant, heterogenic, and drug resistant tumor. The blood-brain barrier (BBB), systemic cytotoxicity, and limited specificity are the main obstacles in designing brain tumor drugs. In this study a computational approach was used to design brain tumor drugs that could downregulate VEGF and IL17A in glioblastoma multiforme type four. Computational screening tools were used to evaluate potential candidates for antiangiogenic activity, target binding, BBB permeability, and ADME physicochemical properties. Additionally, in vitro cytotoxicity, migration, invasion, tube formation, apoptosis, ROS and ELISA assays were conducted for molecule 6 that was deemed most likely to succeed. The efflux ratio of membrane permeability and calculated docking scores of permeability to glycoproteins (P-gps) were used to determine the BBB permeability of the molecules. The results showed BBB permeation for molecule 6, with the predicted efficiency of 0.55kcal/mol and binding affinity of -37kj/mol corresponding to an experimental efflux ratio of 0.625 and predicted -15kj/mol of binding affinity for P-gps. Molecule 6 significantly affected the angiogenesis pathways by 2-fold downregulation of IL17A and VEGF through inactivation of active sites of HSP90 (predicted binding: -37kj/mol, predicted efficiency: 0.55kcal/mol) and p23 (predicted binding: 12kj/mol, predicted efficiency: 0.17kcal/mol) chaperon proteins. Additionally, molecule 6 activated the 17.38% relative fold of ROS level at 18.3μg/mL and upregulated the caspase which lead the potential synergistic apoptosis through the antiangiogenic activity of molecule 6 and thereby the highly efficacious anticancer upshot. The results indicate that the binding of the molecules to the therapeutic target is not essential to produce a lethal effect on cancer cells of the brain and that antiangiogenic efficiency is much more important.
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Affiliation(s)
- Md Shamsuddin Sultan Khan
- EMAN Cancer Research Laboratory, Department of Pharmacology, School of Pharmaceutical Sciences, Universiti Sains Malaysia, Minden, Pulau Pinang, Malaysia.
| | - Amin Malik Shah Abdul Majid
- EMAN Cancer Research Laboratory, Department of Pharmacology, School of Pharmaceutical Sciences, Universiti Sains Malaysia, Minden, Pulau Pinang, Malaysia.
| | - Muhammad Adnan Iqbal
- The School of Chemical Sciences, Universiti Sains Malaysia (USM), 11800 Penang, Malaysia
| | - Aman Shah Abdul Majid
- EMAN Cancer Research Laboratory, Department of Pharmacology, School of Pharmaceutical Sciences, Universiti Sains Malaysia, Minden, Pulau Pinang, Malaysia; QUEST International University, Ipoh, Perak, Malaysia
| | - Majed Al-Mansoub
- EMAN Cancer Research Laboratory, Department of Pharmacology, School of Pharmaceutical Sciences, Universiti Sains Malaysia, Minden, Pulau Pinang, Malaysia
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Sun X, Chuang JC, Kanchwala M, Wu L, Celen C, Li L, Liang H, Zhang S, Maples T, Nguyen LH, Wang SC, Signer RAJ, Sorouri M, Nassour I, Liu X, Xu J, Wu M, Zhao Y, Kuo YC, Wang Z, Xing C, Zhu H. Suppression of the SWI/SNF Component Arid1a Promotes Mammalian Regeneration. Cell Stem Cell 2016; 18:456-66. [PMID: 27044474 DOI: 10.1016/j.stem.2016.03.001] [Citation(s) in RCA: 93] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2015] [Revised: 01/07/2016] [Accepted: 03/02/2016] [Indexed: 01/10/2023]
Abstract
Mammals have partially lost the extensive regenerative capabilities of some vertebrates, possibly as a result of chromatin-remodeling mechanisms that enforce terminal differentiation. Here, we show that deleting the SWI/SNF component Arid1a substantially improves mammalian regeneration. Arid1a expression is suppressed in regenerating tissues, and genetic deletion of Arid1a increases tissue repair following an array of injuries. Arid1a deficiency in the liver increases proliferation, reduces tissue damage and fibrosis, and improves organ function following surgical resection and chemical injuries. Hepatocyte-specific deletion is also sufficient to increase proliferation and regeneration without excessive overgrowth, and global Arid1a disruption potentiates soft tissue healing in the ear. We show that Arid1a loss reprograms chromatin to restrict promoter access by transcription factors such as C/ebpα, which enforces differentiation, and E2F4, which suppresses cell-cycle re-entry. Thus, epigenetic reprogramming mediated by deletion of a single gene improves mammalian regeneration and suggests strategies to promote tissue repair after injury.
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Affiliation(s)
- Xuxu Sun
- Departments of Pediatrics and Internal Medicine, Children's Research Institute, Center for Regenerative Science and Medicine, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Jen-Chieh Chuang
- Departments of Pediatrics and Internal Medicine, Children's Research Institute, Center for Regenerative Science and Medicine, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Mohammed Kanchwala
- Bioinformatics Core, Eugene McDermott Center for Human Growth & Development, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Linwei Wu
- Departments of Pediatrics and Internal Medicine, Children's Research Institute, Center for Regenerative Science and Medicine, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA; Organ Transplant Center, First Affiliated Hospital of Sun Yat-Sen University, Guangzhou 510080, China
| | - Cemre Celen
- Departments of Pediatrics and Internal Medicine, Children's Research Institute, Center for Regenerative Science and Medicine, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Lin Li
- Departments of Pediatrics and Internal Medicine, Children's Research Institute, Center for Regenerative Science and Medicine, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Hanquan Liang
- Bioinformatics Core, Eugene McDermott Center for Human Growth & Development, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Shuyuan Zhang
- Departments of Pediatrics and Internal Medicine, Children's Research Institute, Center for Regenerative Science and Medicine, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Thomas Maples
- Departments of Pediatrics and Internal Medicine, Children's Research Institute, Center for Regenerative Science and Medicine, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Liem H Nguyen
- Departments of Pediatrics and Internal Medicine, Children's Research Institute, Center for Regenerative Science and Medicine, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA; Howard Hughes Medical Institute, Chevy Chase, MD 20815, USA
| | - Sam C Wang
- Departments of Pediatrics and Internal Medicine, Children's Research Institute, Center for Regenerative Science and Medicine, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA; Department of Surgery, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Robert A J Signer
- Division of Regenerative Medicine, Department of Medicine, Moores Cancer Center, University of California, San Diego, La Jolla, CA 92093, USA
| | - Mahsa Sorouri
- Departments of Pediatrics and Internal Medicine, Children's Research Institute, Center for Regenerative Science and Medicine, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Ibrahim Nassour
- Departments of Pediatrics and Internal Medicine, Children's Research Institute, Center for Regenerative Science and Medicine, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA; Department of Surgery, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Xin Liu
- Departments of Pediatrics and Internal Medicine, Children's Research Institute, Center for Regenerative Science and Medicine, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Jian Xu
- Departments of Pediatrics and Internal Medicine, Children's Research Institute, Center for Regenerative Science and Medicine, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Meng Wu
- Mindich Child Health and Development Institute and Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - Yong Zhao
- Mindich Child Health and Development Institute and Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - Yi-Chun Kuo
- Departments of Pharmacology and Biophysics, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Zhong Wang
- Department of Cardiac Surgery, Cardiovascular Research Center, University of Michigan, 2800 Plymouth Road, Ann Arbor, MI 48109, USA
| | - Chao Xing
- Bioinformatics Core, Eugene McDermott Center for Human Growth & Development, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Hao Zhu
- Departments of Pediatrics and Internal Medicine, Children's Research Institute, Center for Regenerative Science and Medicine, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA.
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14
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Tan M, Wettersten HI, Chu K, Huso DL, Watnick T, Friedlander S, Landesman Y, Weiss RH. Novel inhibitors of nuclear transport cause cell cycle arrest and decrease cyst growth in ADPKD associated with decreased CDK4 levels. Am J Physiol Renal Physiol 2014; 307:F1179-86. [PMID: 25234309 PMCID: PMC4254973 DOI: 10.1152/ajprenal.00406.2014] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2014] [Accepted: 09/16/2014] [Indexed: 02/07/2023] Open
Abstract
Autosomal-dominant polycystic kidney disease (ADPKD) is a progressive, proliferative renal disease. Kidneys from ADPKD patients are characterized by the presence of cysts that are marked by enhanced proliferation and apoptosis of renal tubular epithelial cells. Current treatment of this disease is supportive, as there are few if any clinically validated targeted therapeutics. Given the parallels between cystic disease and cancer, and in light of our findings of the efficacy of the nuclear transport inhibitors in kidney cancer, which has similarities to ADPKD, we asked whether such inhibitors show utility in ADPKD. In this study, we tested selective inhibitors of nuclear export (SINE) in two human ADPKD cell lines and in an in vivo mouse model of ADPKD. After effective downregulation of a nuclear exporter, exportin 1 (XPO1), with KPT-330, both cell lines showed dose-dependent inhibition of cell proliferation through G₀/G₁ arrest associated with downregulation of CDK4, with minimal apoptosis. To analyze mechanisms of CDK4 decrease by XPO1 inhibition, localization of various XPO1 target proteins was examined, and C/EBPβ was found to be localized in the nucleus by XPO1 inhibition, resulting in an increase of C/EBPα, which activates degradation of CDK4. Furthermore, inhibition of XPO1 with the parallel inhibitor KPT-335 attenuated cyst growth in vivo in the PKD1 mutant mouse model Pkd1(v/v). Thus, inhibition of nuclear export by KPT-330, which has shown no adverse effects in renal serum chemistries and urinalyses in animal models, and which is already in phase 1 trials for cancers, will be rapidly translatable to human ADPKD.
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Affiliation(s)
| | | | - Kristy Chu
- Department of Molecular and Comparative Pathobiology, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - David L Huso
- Department of Molecular and Comparative Pathobiology, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Terry Watnick
- Division of Nephrology, University of Maryland School of Medicine, Baltimore, Maryland
| | | | | | - Robert H Weiss
- Graduate Group in Comparative Pathology, Division of Nephrology, Department of Internal Medicine, and Cancer Center, University of California, Davis, California; Medical Service, Sacramento Veterans Affairs Medical Center, Sacramento, California
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15
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Regulatory role of the 90-kDa-heat-shock protein (Hsp90) and associated factors on gene expression. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2014; 1839:71-87. [DOI: 10.1016/j.bbagrm.2013.12.006] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/18/2013] [Revised: 12/23/2013] [Accepted: 12/26/2013] [Indexed: 12/31/2022]
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16
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Norrie IC, Ohlsson E, Nielsen O, Hasemann MS, Porse BT. C/EBPα is dispensable for the ontogeny of PD-1+ CD4+ memory T cells but restricts their expansion in an age-dependent manner. PLoS One 2014; 9:e84728. [PMID: 24404186 PMCID: PMC3880335 DOI: 10.1371/journal.pone.0084728] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2013] [Accepted: 11/19/2013] [Indexed: 11/19/2022] Open
Abstract
Ageing and cancer is often associated with altered T cell distributions and this phenomenon has been suggested to be the main driver in the development of immunosenescence. Memory phenotype PD-1+ CD4+ T cells accumulate with age and during leukemic development, and they might account for the attenuated T cell response in elderly or diseased individuals. The transcription factor C/EBPα has been suggested to be responsible for the accumulation as well as for the senescent features of these cells including impaired TCR signaling and decreased proliferation. Thus modulating the activity of C/EBPα could potentially target PD-1+ CD4+ T cells and consequently, impede the development of immunosenescence. To exploit this possibility we tested the importance of C/EBPα for the development of age-dependent PD-1+ CD4+ T cells as well as its role in the accumulation of PD-1+ CD4+ T cells during leukemic progression. In contrast to earlier suggestions, we find that loss of C/EBPα expression in the lymphoid compartment led to an increase of PD-1+ CD4+ T cells specifically in old mice, suggesting that C/EBPα repress the accumulation of these cells in elderly by inhibiting their proliferation. Furthermore, C/EBPα-deficiency in the lymphoid compartment had no effect on leukemic development and did not affect the accumulation of PD-1+ CD4+ T cells. Thus, in addition to contradict earlier suggestions of a role for C/EBPα in immunosenescence, these findings efficiently discard the potential of using C/EBPα as a target for the alleviation of ageing/cancer-associated immunosenescence.
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Affiliation(s)
- Ida Christine Norrie
- Finsen Laboratory, Rigshospitalet, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark
- Biotech Research and Innovation Center (BRIC), University of Copenhagen, Copenhagen, Denmark
- Danish Stem Cell Centre (DanStem) Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark
- Institute of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Ewa Ohlsson
- Finsen Laboratory, Rigshospitalet, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark
- Biotech Research and Innovation Center (BRIC), University of Copenhagen, Copenhagen, Denmark
- Danish Stem Cell Centre (DanStem) Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Olaf Nielsen
- Institute of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Marie Sigurd Hasemann
- Finsen Laboratory, Rigshospitalet, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark
- Biotech Research and Innovation Center (BRIC), University of Copenhagen, Copenhagen, Denmark
- Danish Stem Cell Centre (DanStem) Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Bo T Porse
- Finsen Laboratory, Rigshospitalet, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark
- Biotech Research and Innovation Center (BRIC), University of Copenhagen, Copenhagen, Denmark
- Danish Stem Cell Centre (DanStem) Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark
- * E-mail:
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17
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Neumann J, Boerries M, Köhler R, Giaisi M, Krammer PH, Busch H, Li-Weber M. The natural anticancer compound rocaglamide selectively inhibits the G1-S-phase transition in cancer cells through the ATM/ATR-mediated Chk1/2 cell cycle checkpoints. Int J Cancer 2013; 134:1991-2002. [PMID: 24150948 DOI: 10.1002/ijc.28521] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2013] [Accepted: 09/19/2013] [Indexed: 02/03/2023]
Abstract
Targeting the cancer cell cycle machinery is an important strategy for cancer treatment. Cdc25A is an essential regulator of cycle progression and checkpoint response. Over-expression of Cdc25A occurs often in human cancers. In this study, we show that Rocaglamide-A (Roc-A), a natural anticancer compound isolated from the medicinal plant Aglaia, induces a rapid phosphorylation of Cdc25A and its subsequent degradation and, thereby, blocks cell cycle progression of tumor cells at the G1-S phase. Roc-A has previously been shown to inhibit tumor proliferation by blocking protein synthesis. In this study, we demonstrate that besides the translation inhibition Roc-A can induce a rapid degradation of Cdc25A by activation of the ATM/ATR-Chk1/Chk2 checkpoint pathway. However, Roc-A has no influence on cell cycle progression in proliferating normal T lymphocytes. Investigation of the molecular basis of tumor selectivity of Roc-A by a time-resolved microarray analysis of leukemic vs. proliferating normal T lymphocytes revealed that Roc-A activates different sets of genes in tumor cells compared with normal cells. In particular, Roc-A selectively stimulates a set of genes responsive to DNA replication stress in leukemic but not in normal T lymphocytes. These findings further support the development of Rocaglamide for antitumor therapy.
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Affiliation(s)
- Jennifer Neumann
- Tumorimmunology Program (D030), German Cancer Research Center (DKFZ), Heidelberg, Germany
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18
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Jin J, Iakova P, Breaux M, Sullivan E, Jawanmardi N, Chen D, Jiang Y, Medrano EM, Timchenko NA. Increased expression of enzymes of triglyceride synthesis is essential for the development of hepatic steatosis. Cell Rep 2013; 3:831-43. [PMID: 23499441 DOI: 10.1016/j.celrep.2013.02.009] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2012] [Revised: 12/12/2012] [Accepted: 02/06/2013] [Indexed: 12/14/2022] Open
Abstract
Molecular mechanisms underpinning nonalcoholic fatty liver disease (NAFLD) are not well understood. The earliest step of NAFLD is hepatic steatosis, which is one of the main characteristics of aging liver. Here, we present a molecular scenario of age-related liver steatosis. We show that C/EBPα-S193D knockin mice have age-associated epigenetic changes and develop hepatic steatosis at 2 months of age. The underlying mechanism of the hepatic steatosis in old wild-type (WT) mice and in young S193D mice includes increased amounts of tripartite p300-C/EBPα/β complexes that activate promoters of five genes that drive triglyceride synthesis. Knockdown of p300 in old WT mice inhibits hepatic steatosis. Indeed, transgenic mice expressing dominant-negative p300 have fewer C/EBPα/β-p300 complexes and do not develop age-dependent hepatic steatosis. Notably, the p300-C/EBPα/β pathway is activated in the livers of patients with NAFLD. Thus, our results show that p300 and C/EBP proteins are essential participants in hepatic steatosis.
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Affiliation(s)
- Jingling Jin
- Huffington Center on Aging and Department of Pathology and Immunology, Baylor College of Medicine, Houston, TX 77030, USA
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19
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Syncytin-1 modulates placental trophoblast cell proliferation by promoting G1/S transition. Cell Signal 2013; 25:1027-35. [PMID: 23333240 DOI: 10.1016/j.cellsig.2013.01.008] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2012] [Revised: 12/22/2012] [Accepted: 01/08/2013] [Indexed: 02/07/2023]
Abstract
Placental syncytiotrophoblasts formed by the fusion of cytotrophoblasts constitute the interface between maternal and fetal circulations. The syncytium, composed of a continuous layer of syncytiotrophoblasts, assumes the fetal-maternal nutrient exchange, placental barrier, and endocrine functions important for the maintenance of normal pregnancy. Syncytin-1, an endogenous retroviral gene product, mediates the fusion of cytotrophoblasts. While the fusogenic function of syncytin-1 has been well established, little is known regarding its nonfusogenic activities. This study investigates the role of syncytin-1 in trophoblast proliferation. We found that syncytin-1 knockdown significantly inhibited BeWo cell growth and DNA synthesis. Moreover, time course studies on key cell cycle regulators demonstrated an upregulation of p15 and downregulation of CDK4, E2F1, PCNA, and c-Myc, which consequently led to a reduced level of CDK1. These results, together with those from flow cytometry analysis, indicated that syncytin-1 knockdown blocked the G1/S transition phase of the cell cycle. Moreover, syncytin-1 overexpression promoted CHO cell proliferation and led to changes opposite to those observed in syncytin-1 knockdown experiments, confirming the critical role of syncytin-1 for G1/S transition. Thus, syncytin-1, through both nonfusogenic and fusogenic, functions, may co-regulate the input (proliferation) and output (fusion) of the cytotrophoblast "pool". Such co-regulation could be an efficient way to achieve the balance between these two opposing processes, which is required for syncytium homeostasis. Since decreased syncytin-1 expression has been shown to be associated with preeclamptic and hypoxic condition, insufficient replenishing of the cytotrophoblast "pool" may contribute to syncytium deficiency, a critical pathological change frequently found in preeclamptic placentas.
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20
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Ali YO, Kitay BM, Zhai RG. Dealing with misfolded proteins: examining the neuroprotective role of molecular chaperones in neurodegeneration. Molecules 2010; 15:6859-87. [PMID: 20938400 PMCID: PMC3133442 DOI: 10.3390/molecules15106859] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2010] [Revised: 09/06/2010] [Accepted: 09/08/2010] [Indexed: 01/19/2023] Open
Abstract
Human neurodegenerative diseases arise from a wide array of genetic and environmental factors. Despite the diversity in etiology, many of these diseases are considered "conformational" in nature, characterized by the accumulation of pathological, misfolded proteins. These misfolded proteins can induce cellular stress by overloading the proteolytic machinery, ultimately resulting in the accumulation and deposition of aggregated protein species that are cytotoxic. Misfolded proteins may also form aberrant, non-physiological protein-protein interactions leading to the sequestration of other normal proteins essential for cellular functions. The progression of such disease may therefore be viewed as a failure of normal protein homeostasis, a process that involves a network of molecules regulating the synthesis, folding, translocation and clearance of proteins. Molecular chaperones are highly conserved proteins involved in the folding of nascent proteins, and the repair of proteins that have lost their typical conformations. These functions have therefore made molecular chaperones an active area of investigation within the field of conformational diseases. This review will discuss the role of molecular chaperones in neurodegenerative diseases, highlighting their functional classification, regulation, and therapeutic potential for such diseases.
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Affiliation(s)
- Yousuf O. Ali
- Department of Molecular and Cellular Pharmacology, University of Miami, Miller School of Medicine, Miami, FL 33136, USA
| | - Brandon M. Kitay
- Department of Molecular and Cellular Pharmacology, University of Miami, Miller School of Medicine, Miami, FL 33136, USA
- Neuroscience Graduate Program, University of Miami, Miller School of Medicine, Miami, FL 33136, USA
| | - R. Grace Zhai
- Department of Molecular and Cellular Pharmacology, University of Miami, Miller School of Medicine, Miami, FL 33136, USA
- Neuroscience Graduate Program, University of Miami, Miller School of Medicine, Miami, FL 33136, USA
- Author to whom correspondence should be addressed; E-Mail: ; Tel.: +1-305-243-6316; Fax: +1-305-243-4555
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21
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Zhang J, Gonit M, Salazar MD, Shatnawi A, Shemshedini L, Trumbly R, Ratnam M. C/EBPalpha redirects androgen receptor signaling through a unique bimodal interaction. Oncogene 2009; 29:723-38. [PMID: 19901962 DOI: 10.1038/onc.2009.373] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Nuclear expression of CCAAT enhancer binding protein-alpha (C/EBPalpha), which supports tissue differentiation through several antiproliferative protein-protein interactions, augurs terminal differentiation of prostate epithelial cells. C/EBPalpha is also a tumor suppressor, but in many tumors its antiproliferative interactions may be attenuated by de-phosphorylation. C/EBPalpha acts as a corepressor of the classical androgen response element (ARE)-mediated gene activation by the androgen receptor (AR), but this is paradoxical as the genotropic actions of AR are crucial not only for the growth of the prostate but also for its maintenance and function. We show that DNA-bound C/EPBalpha recruits AR to activate transcription. C/EBPalpha-dependent trans-activation by AR also overrode suppression of AREs by C/EBPalpha elsewhere in a promoter. This mechanism was remarkable in that its androgen dependence was apparently for nuclear translocation of AR; it was otherwise androgen independent, flutamide insensitive and tolerant to disruption of AR dimerization. Gene response profiles and global chromatin associations in situ supported the direct bimodal regulation of AR transcriptional signaling by C/EBPalpha. This unique mechanism explains the functional coordination between AR and C/EPBalpha in the prostate and also shows that hormone-refractory AR signaling in prostate cancer could occur through receptor tethering.
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Affiliation(s)
- J Zhang
- Department of Biochemistry and Cancer Biology, Medical University of Ohio, Toledo, OH 43614, USA
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22
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Abstract
Protein kinases are important regulators of intracellular signal transduction pathways and play critical roles in diverse cellular functions. Once a protein kinase is activated, its activity is subsequently downregulated through a variety of mechanisms. Accumulating evidence indicates that the activation of protein kinases commonly initiates their downregulation via the ubiquitin/proteasome pathway. Failure to regulate protein kinase activity or expression levels can cause human diseases.
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Affiliation(s)
- Zhimin Lu
- Department of Neuro-Oncology and Molecular and Cellular Oncology, University of Texas M. D. Anderson Cancer, Houston, TX 77030, USA.
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23
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Meyer F, Jones C. The cellular transcription factor, CCAAT enhancer-binding protein alpha (C/EBP-alpha), has the potential to activate the bovine herpesvirus 1 immediate-early transcription unit 1 promoter. J Neurovirol 2009; 15:123-30. [PMID: 19115128 DOI: 10.1080/13550280802534771] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
Following acute infection, bovine herpesvirus-1 (BHV-1) establishes a lifelong latent infection in sensory neurons of trigeminal ganglia. BHV-1 periodically reactivates from latency and is shed as infectious virus. The latency-related (LR) gene is abundantly expressed in trigeminal ganglia of infected calves, and proteins encoded by the LR gene are necessary for reactivation from latency. We previously demonstrated that a novel LR protein interacts with a host transcription factor, CCAAT enhancer-binding protein alpha (C/EBPalpha). C/EBPalpha increases plaque-forming efficiency when cotransfected with BHV-1 DNA and its expression is induced in neurons during reactivation from latency (Meyer et al, 2007, J Virol 81: 59-67). The ability of C/EBPalpha to bind DNA is necessary for stimulating productive infection, suggesting C/EBPalpha stimulates viral transcription. We tested whether C/EBPalpha could trans-activate the BHV-1 immediate early transcription unit 1 (IEtu1) promoter because the IEtu1 promoter activates expression of two viral genes (bICP0 and bICP4) that stimulate producitve infection. In the current study, We demonstrate that C/EBPalpha and the BHV-1 trans-inducing factor (bTIF) synergistically trans-activate IEtu1 promoter activity. However, bICP0 and C/EBPalpha did not synergistically trans-activate IEtu1 promoter activity. Deletion of IEtu1 promoter sequences demonstrated that C/EBPalpha by itself could trans-activate a truncated IEtu1 promoter, suggesting sequences in the distal region of the IEtu1 promoter negatively regulate C/EBPalpha activtiy. These studies suggest that C/EBPalpha stimulates productive infection and reactivation from latency, in part, by cooperating with bTIF to activate IEtu1 promoter activity.
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Affiliation(s)
- Florencia Meyer
- Department of Veterinary and Biomedical Sciences, School of Biological Sciences, Nebraska Center for Virology, University of Nebraska, Lincoln, Nebraska 68503, USA
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24
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Lyu J, Wesselschmidt RL, Lu W. Cdc37 regulates Ryk signaling by stabilizing the cleaved Ryk intracellular domain. J Biol Chem 2009; 284:12940-8. [PMID: 19269974 PMCID: PMC2676025 DOI: 10.1074/jbc.m900207200] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2009] [Revised: 03/04/2009] [Indexed: 12/31/2022] Open
Abstract
Ryk is a Wnt receptor that plays an important role in neurogenesis, neurite outgrowth, and axon guidance. We have reported that the Ryk receptor is cleaved by gamma-secretase and that its intracellular domain (ICD) translocates to the nucleus upon Wnt stimulation. Cleavage of Ryk and its ICD is important for the function of Ryk in neurogenesis. However, the question of how the Ryk ICD is stabilized and translocated into the nucleus remains unanswered. Here, we show that the Ryk ICD undergoes ubiquitination and proteasomal degradation. We have identified Cdc37, a subunit of the molecular chaperone Hsp90 complex, as a Ryk ICD-interacting protein that inhibits proteasomal degradation of the Ryk ICD. Overexpression of Cdc37 increases Ryk ICD levels and promotes its nuclear localization, whereas Cdc37 knockdown reduces Ryk ICD stability. Furthermore, we have discovered that the Cdc37-Ryk ICD complex is disrupted during neural differentiation of embryonic stem cells, resulting in Ryk ICD degradation. These results suggest that Cdc37 plays an essential role in regulating Ryk ICD stability and therefore in Ryk-mediated signal transduction.
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Affiliation(s)
- Jungmook Lyu
- The Eli and Edythe Broad Center for Regenerative Medicine and Stem Cell Research, Keck School of Medicine, University of Southern California, Los Angeles, CA 90033, USA.
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25
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Sun Q, Zhang F, Wafa K, Baptist T, Pasumarthi KBS. A splice variant of cyclin D2 regulates cardiomyocyte cell cycle through a novel protein aggregation pathway. J Cell Sci 2009; 122:1563-73. [PMID: 19401331 DOI: 10.1242/jcs.047738] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The mammalian heart lacks intrinsic ability to replace diseased myocardium with newly divided myocytes. There is scant information on mechanisms regulating cell cycle exit in cardiomyocytes. We cloned a splice variant of cyclin D2 (D2SV) from the mouse heart and found a novel role for this protein in cardiomyocyte cell cycle exit. We report that D2SV is highly expressed in embryonic myocardium compared with the adult heart. Localization studies indicate that D2SV is retained in the endoplasmic reticulum (ER), Golgi and lysosomal compartments and subjected to ER-stress-associated protein aggregation. D2SV aggregation relies on the motor activities of dynein and is blocked by ER stress modulators. The ability of D2SV to sequester other cell cycle proteins provides a mechanistic explanation for its effects on cardiomyocyte cell cycle. We show that D2SV-induced cell cycle exit can be rescued by overexpression of D-type and B-type cyclins. We suggest that protein aggregation may be a major block for cardiomyocyte cell cycle reactivation.
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Affiliation(s)
- Qian Sun
- Department of Pharmacology, Sir Charles Tupper Medical Building, Dalhousie University, Halifax, NS, B3H 1X5 Canada
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26
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Smith JR, Clarke PA, de Billy E, Workman P. Silencing the cochaperone CDC37 destabilizes kinase clients and sensitizes cancer cells to HSP90 inhibitors. Oncogene 2008; 28:157-69. [PMID: 18931700 PMCID: PMC2635547 DOI: 10.1038/onc.2008.380] [Citation(s) in RCA: 96] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
The cochaperone CDC37 promotes association of HSP90 with the protein kinase subset of client proteins to maintain their stability and signalling functions. HSP90 inhibitors induce depletion of clients, which include several oncogenic kinases. We hypothesised that the targeting of CDC37 using siRNAs would compromise the maturation of these clients and increase the sensitivity of cancer cells to HSP90 inhibitors. Here we show that silencing of CDC37 in human colon cancer cells diminished association of kinase clients with HSP90 and reduced levels of the clients ERBB2, CRAF, CDK4 and CDK6, as well as phosphorylated AKT. CDC37 silencing promoted the proteasome-mediated degradation of kinase clients, suggesting a degradation pathway independent from HSP90 binding. Decreased cell signalling through kinase clients was also demonstrated by reduced phosphorylation of downstream substrates and colon cancer cell proliferation was subsequently reduced by inhibition of the G1/S-phase transition. Furthermore, combining CDC37 silencing with the HSP90 inhibitor 17-AAG induced more extensive and sustained depletion of kinase clients and potentiated cell cycle arrest and apoptosis. These results support an essential role for CDC37 in concert with HSP90 in maintaining oncogenic protein kinase clients and endorse the therapeutic potential of targeting CDC37 in cancer.
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Affiliation(s)
- J R Smith
- Signal Transduction and Molecular Pharmacology Team, Cancer Research UK Centre for Cancer Therapeutics, The Institute of Cancer Research, Haddow Laboratories, Surrey, UK
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27
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Zhang J, Wilkinson JE, Gonit M, Keck R, Selman S, Ratnam M. Expression and sub-cellular localization of the CCAAT/enhancer binding protein alpha in relation to postnatal development and malignancy of the prostate. Prostate 2008; 68:1206-14. [PMID: 18481268 PMCID: PMC3911780 DOI: 10.1002/pros.20779] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
BACKGROUND C/EBPalpha is a critical mediator of terminal differentiation and a tumor suppressor through its strong antiproliferative actions on cell cycle regulatory proteins. C/EBPalpha also appears to regulate androgen receptor (AR) AR signaling. There, is a paucity of information on the expression and sub-cellular localization of C/EBPalpha in normal mouse and human prostate and in prostate cancer. METHODS Immunohistochemistry of tissues including tissue arrays, quantitative polymerase chain reaction and mRNA expression database mining. RESULTS In the mouse prostate epithelium, C/EBPalpha was present at 1 week postnatal localized in the cytosol, began to show nuclear localization at 8 weeks and continued to show prominent nuclear expression at 10 weeks and beyond; C/EBPalpha mRNA was expressed at all ages. In humans, C/EBPalpha showed prominent nuclear localization from peripubescence up to middle age but was sequestered in the cytosol in older individuals; the mRNA level for C/EBPalpha remained essentially unchanged. Most prostate adenocarcinomas expressed a range of levels of C/EBPalpha mRNA and protein that were relatively high in metastatic tumors in a manner that correlated with AR expression; however, most cells showed C/EBPalpha sequestered in the cytosol. CONCLUSIONS Temporal changes in sub-cellular localization of C/EBPalpha are consistent with a role in prostate differentiation and as a prostate tumor suppressor; the cytoplasmic sequestration of C/EBPalpha, unique to older human prostates, is arguably a permissive condition for the greater frequency of proliferative disorders of the prostate. In malignant prostate C/EBPalpha may be available to regulate AR signaling through transient changes in its sub-cellular localization.
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Affiliation(s)
- Juan Zhang
- Department of Biochemistry and Cancer Biology, Medical University of Ohio, Toledo, Ohio
| | - John Erby Wilkinson
- Department of Pathology, University of Michigan School of Medicine, Ann Arbor, Michigan
| | - Mesfin Gonit
- Department of Biochemistry and Cancer Biology, Medical University of Ohio, Toledo, Ohio
| | - Rick Keck
- Department of Urology, Medical University of Ohio, Toledo, Ohio
| | - Steven Selman
- Department of Urology, Medical University of Ohio, Toledo, Ohio
| | - Manohar Ratnam
- Department of Biochemistry and Cancer Biology, Medical University of Ohio, Toledo, Ohio
- Correspondence to: Prof. Manohar Ratnam, 3000 Arlington Avenue, Toledo, OH 43614.
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Elucidation of susceptible factors to endoplasmic reticulum stress-mediated anticancer activity in human hepatocellular carcinoma. NAUNYN-SCHMIEDEBERG'S ARCHIVES OF PHARMACOLOGY 2008; 377:167-77. [PMID: 18228003 DOI: 10.1007/s00210-007-0249-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/2007] [Accepted: 12/12/2007] [Indexed: 10/22/2022]
Abstract
The initiation of endoplasmic reticulum (ER) stress has been suggested to play potential roles in hepatocarcinogenesis. However, many obstacles remain as to whether ER stress plays a role in carcinogenesis or tumoricide. This study sought to identify the signals that can serve as anticancer effectors in cells in response to ER stress. Tunicamycin (an N-glycosylation inhibitor) inhibited cell proliferation with IC(50) values of 0.19 and 0.62 microg/ml in hepatoma (Hep) 3B and HepG2 cells, respectively. It induced G1 arrest of the cell cycle in both cell lines. The anticancer mechanism of tunicamycin was investigated in Hep3B cells. Tunicamycin induced a rapid decline of cyclin D1 and cyclin A expression and an early increase of glucose-related protein (GRP) 78 and growth arrest and DNA damage-inducible transcription factor (GADD) 153 levels. Cyclin A was the most sensitive regulator to tunicamycin-triggered degradation mechanism. The association of p27(Kip1) with cyclin D1/cyclin-dependent kinase (Cdk) 4 was also increased by tunicamycin. The inhibition of GADD153 expression by transfection of GADD153 antisense did not modify tunicamycin-induced G1 arrest and cyclin/Cdk expressions. The knockdown of GRP78 expression by the siRNA transfection technique moderately increased tunicamycin-induced apoptosis but not the antiproliferative effect by sulforhodamine B assay. We suggest that tunicamycin induces G1 arrest through down-regulation of cyclins and Cdks, in which cyclin A is more susceptible to ER stress-triggered degradation mechanism in Hep3B cells. The increased association of p27(Kip1) with cyclin D1/Cdk4 may also contribute to tunicamycin-induced cell-cycle arrest. GADD153 and GRP78 play a minor role in tunicamycin-mediated antiproliferative effect, although GRP78 moderately inhibits apoptosis in Hep3B cells. These data provide evidence that cell-cycle regulators are susceptible factors in hepatocellular carcinoma (HCC) responsive to ER stress.
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Gilgenkrantz H, Guidotti JE. [Decline of liver'age-dependent regenerative capacities: some molecular tracks]. Med Sci (Paris) 2007; 23:1082-4. [PMID: 18154706 DOI: 10.1051/medsci/200723121082] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Lindberg D, Hessman O, Akerström G, Westin G. Cyclin-dependent kinase 4 (CDK4) expression in pancreatic endocrine tumors. Neuroendocrinology 2007; 86:112-8. [PMID: 17664862 DOI: 10.1159/000106762] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/01/2007] [Accepted: 06/26/2007] [Indexed: 12/21/2022]
Abstract
BACKGROUND/AIMS Pancreatic endocrine tumors (PETs) occur sporadically, in association with the multiple endocrine neoplasia type 1 (MEN1) and the von Hippel-Lindau syndromes. CDK4 is central to the cell cycle control in pancreatic beta cells, and we have assessed whether CDK4 expression is deregulated in 18 human sporadic or familial PETs. METHODS Real-time quantitative PCR, immunohistochemistry, DNA sequencing, and Western blot analysis were used. RESULTS CDK4 mRNA was expressed in all PETs within the range of the arbitrary control. CDK4 protein was absent in normal pancreatic islets but distinctly expressed in all PETs as determined by immunohistochemistry. CDK4 expression was confirmed by Western blot analysis. No significant differences of CDK4 expression were observed between the groups of benign and malignant PETs or between tumors with or without MEN1 gene mutations. CDK4 expression was not due to gene amplification, and no mutations were identified in coding exons and RNA splice sites. c-Myc is known to be overexpressed in PETs and directly augments CDK4 expression in other cell types. Analysis of consecutive tissue sections for CDK4 and c-Myc showed overlapping homo- or heterogeneous immunostaining in all 18 PETs. CONCLUSION We conclude that CDK4 and c-Myc is generally expressed in benign and malignant PETs, and regardless of MEN1 mutational status. Targeting of CDK4 may present an alternative to traditional chemotherapy of PETs in the future.
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Affiliation(s)
- Daniel Lindberg
- Department of Surgical Sciences, Endocrine Unit, Uppsala University Hospital, Uppsala, Sweden
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31
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Wang GL, Shi X, Salisbury E, Sun Y, Albrecht JH, Smith RG, Timchenko NA. Cyclin D3 maintains growth-inhibitory activity of C/EBPalpha by stabilizing C/EBPalpha-cdk2 and C/EBPalpha-Brm complexes. Mol Cell Biol 2006; 26:2570-82. [PMID: 16537903 PMCID: PMC1430318 DOI: 10.1128/mcb.26.7.2570-2582.2006] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
C/EBPalpha arrests proliferation of young livers by inhibition of cdk2. In old mice, C/EBPalpha inhibits growth by repression of E2F-dependent promoters through the C/EBPalpha-Brm complex. In this paper, we show that cyclin D3-cdk4/cdk6 supports the ability of C/EBPalpha to inhibit liver proliferation in both age groups. Although cyclin D3-cdk4/cdk6 kinases are involved in the promotion of growth, they are expressed in terminally differentiated cells, suggesting that they have additional functions in these settings. We demonstrate that C/EBPalpha represents a target for phosphorylation by cyclin D3-cdk4/cdk6 complexes in differentiated liver cells and in differentiated adipocytes. Cyclin D3-cdk4/cdk6 specifically phosphorylate C/EBPalpha at Ser193 in vitro and in the liver and support growth-inhibitory C/EBPalpha-cdk2 and C/EBPalpha-Brm complexes. We found that cyclin D3 is increased in old livers and activates cdk4/cdk6, resulting in stabilization of the C/EBPalpha-Brm complex. Old livers fail to reduce the activity of cyclin D3-cdk4/cdk6 after partial hepatectomy, leading to high levels of C/EBPalpha-Brm complexes after partial hepatectomy, which correlate with weak proliferation. We examined the role of cyclin D3 in the stabilization of C/EBPalpha-cdk2 and C/EBPalpha-Brm by using 3T3-L1 differentiated cells. In these cells, cyclin D3 is increased during differentiation and phosphorylates C/EBPalpha at Ser193, leading to the formation of growth-inhibitory C/EBPalpha-cdk2 and C/EBPalpha-Brm complexes. The inhibition of cyclin D3 blocks the formation of these complexes. Thus, these studies provide a new function of cyclin D3, which is to support the growth-inhibitory activity of C/EBPalpha.
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Affiliation(s)
- Guo-Li Wang
- Huffington Center on Aging, Baylor College of Medicine, One Baylor Plaza, Houston, Texas 77030, USA
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32
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Citri A, Harari D, Shohat G, Ramakrishnan P, Gan J, Lavi S, Eisenstein M, Kimchi A, Wallach D, Pietrokovski S, Yarden Y. Hsp90 recognizes a common surface on client kinases. J Biol Chem 2006; 281:14361-9. [PMID: 16551624 DOI: 10.1074/jbc.m512613200] [Citation(s) in RCA: 178] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Hsp90 is a highly abundant chaperone whose clientele includes hundreds of cellular proteins, many of which are central players in key signal transduction pathways and the majority of which are protein kinases. In light of the variety of Hsp90 clientele, the mechanism of selectivity of the chaperone toward its client proteins is a major open question. Focusing on human kinases, we have demonstrated that the chaperone recognizes a common surface in the amino-terminal lobe of kinases from diverse families, including two newly identified clients, NFkappaB-inducing kinase and death-associated protein kinase, and the oncoprotein HER2/ErbB-2. Surface electrostatics determine the interaction with the Hsp90 chaperone complex such that introduction of a negative charge within this region disrupts recognition. Compiling information on the Hsp90 dependence of 105 protein kinases, including 16 kinases whose relationship to Hsp90 is first examined in this study, reveals that surface features, rather than a contiguous amino acid sequence, define the capacity of the Hsp90 chaperone machine to recognize client kinases. Analyzing Hsp90 regulation of two major signaling cascades, the mitogen-activated protein kinase and phosphatidylinositol 3-kinase, leads us to propose that the selectivity of the chaperone to specific kinases is functional, namely that Hsp90 controls kinases that function as hubs integrating multiple inputs. These lessons bear significance to pharmacological attempts to target the chaperone in human pathologies, such as cancer.
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Affiliation(s)
- Ami Citri
- Department of Biological Regulation, Weizmann Institute of Science, Rehovot 97100, Israel
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Nakajima H, Watanabe N, Shibata F, Kitamura T, Ikeda Y, Handa M. N-terminal region of CCAAT/enhancer-binding protein epsilon is critical for cell cycle arrest, apoptosis, and functional maturation during myeloid differentiation. J Biol Chem 2006; 281:14494-502. [PMID: 16531405 DOI: 10.1074/jbc.m600575200] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
CCAAT/enhancer-binding protein epsilon (C/EBPepsilon) plays a critical role in terminal myeloid differentiation. Differentiation is an integrated process of cell cycle arrest, morphological change, functional maturation, and apoptosis. However, the molecular networks underlying these events in C/EBPepsilon-induced differentiation remain poorly understood. To reveal these mechanisms, we performed a detailed molecular analysis of C/EBPepsilon-induced differentiation using an inducible form of C/EBPepsilon. The activation of C/EBPepsilon induced growth arrest, morphological differentiation, the expression of CD11b and secondary granule proteins, and apoptosis in myeloid cell lines. Unlike C/EBPalpha, C/EBPepsilon dramatically up-regulated p27 with a concomitant down-regulation of cdk4/6 and cyclin D2/A/E. Moreover, the anti-apoptotic proteins Bcl-2 and Bcl-x were down-regulated, whereas pro-apoptotic protein Bax remained unchanged. Using a variety of mutants, we revealed that these events were all regulated by the N-terminal activation domain of C/EBPepsilon. Interestingly, some of the differentiation processes such as the induction of secondary granule protein genes were clearly inhibited by c-Myc; however, inhibition of apoptosis by Bcl-x did not affect the entire differentiation processes. These data indicate the N terminus of C/EBPepsilon to be solely responsible for most aspects of myeloid differentiation, and these events were differentially affected by c-Myc.
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Affiliation(s)
- Hideaki Nakajima
- Center of Excellence, The Institute of Medical Science, The University of Tokyo, Tokyo 108-8639, Japan.
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Huang J, Liao G, Chen H, Wu FY, Hutt-Fletcher L, Hayward GS, Hayward SD. Contribution of C/EBP proteins to Epstein-Barr virus lytic gene expression and replication in epithelial cells. J Virol 2006; 80:1098-109. [PMID: 16414987 PMCID: PMC1346937 DOI: 10.1128/jvi.80.3.1098-1109.2006] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The contribution of C/EBP proteins to Epstein-Barr virus (EBV) lytic gene expression and replication in epithelial cells was examined. Nasopharyngeal carcinoma cell lines constitutively expressed C/EBPbeta and had limited C/EBPalpha expression, while the AGS gastric cancer cell line expressed significant levels of both C/EBPalpha and C/EBPbeta. Induction of the lytic cycle in EBV-positive AGS/BX1 cells with phorbol ester and sodium butyrate treatment led to a transient stimulation of C/EBPbeta expression and a prolonged increase in C/EBPalpha expression. In AGS/BX1 cells, endogenous C/EBPalpha and C/EBPbeta proteins were detected associated with the ZTA and oriLyt promoters but not the RTA promoter. Electrophoretic mobility shift assays confirmed binding of C/EBP proteins to multiple sites in the ZTA and oriLyt promoters. The response of these promoters in reporter assays to transfected C/EBPalpha and C/EBPbeta proteins was consistent with the promoter binding assays and emphasized the relative importance of C/EBPs for activation of the ZTA promoter. Mutation of the oriLyt promoter proximal C/EBP site had little effect on ZTA activation of the promoter in a reporter assay. However, this mutation impaired oriLyt DNA replication, suggesting a separate replication-specific contribution for C/EBP proteins. Finally, the overall importance of C/EBP proteins for lytic gene expression was demonstrated using CHOP10 to antagonize C/EBP DNA binding activity. Introduction of CHOP10 significantly impaired induction of the ZTA, RTA, and BMRF1 proteins in chemically treated AGS/BX1 cells. Thus, C/EBPbeta and C/EBPalpha expression are associated with lytic induction in AGS cells, and expression of C/EBP proteins in epithelial cells may contribute to the tendency of these cells to exhibit constitutive low-level ZTA promoter activity.
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Affiliation(s)
- Jian Huang
- Johns Hopkins School of Medicine, Bunting-Blaustein Building CRB308, 1650 Orleans Street, Baltimore, MD 21231-1000, USA
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35
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Tang D, Sivko GS, DeWille JW. Promoter methylation reduces C/EBPdelta (CEBPD) gene expression in the SUM-52PE human breast cancer cell line and in primary breast tumors. Breast Cancer Res Treat 2005; 95:161-70. [PMID: 16322893 DOI: 10.1007/s10549-005-9061-3] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/22/2005] [Indexed: 11/25/2022]
Abstract
CCAAT/Enhancer Binding Proteins (C/EBPs) are a highly conserved family of leucine zipper proteins that regulate cell growth and differentiation. C/EBPdelta functions in the initiation and maintenance of mammary epithelial cell G(0) growth arrest and 'loss of function' alterations in C/EBPdelta gene expression have been reported in human breast cancer and in rodent carcinogen-induced mammary tumors. The molecular mechanism underlying reduced C/EBPdelta gene expression in mammary tumorigenesis, however, is unknown. In this report we demonstrate that C/EBPdelta gene expression is undetectable in the SUM-52PE human breast cancer cell line and that silencing of SUM-52PE C/EBPdelta gene expression is due to epigenetic promoter hypermethylation (26/27 CpGs methylated). The hypermethylated SUM-52PE C/EBPdelta gene promoter is associated with reduced levels of acetylated Histone H4, consistent with a closed, transcriptionally inactive chromatin conformation. Treatment with 5'-aza-cytidine and trichostatin A (TSA) re-activates cytokine-induced SUM-52PE C/EBPdelta gene expression. C/EBPdelta gene expression is reduced to virtually undetectable levels in 32% (18/57) of primary human breast tumors. Site-specific CpG methylation was observed in 33% (6/18) of the low C/EBPdelta expressing primary breast tumors. CpG methylation adjacent to the C/EBPdelta proximal promoter Sp1 site was associated with reduced C/EBPdelta expression in a primary breast cancer sample. Electromobility shift assays (EMSA) demonstrated a significant reduction in binding to oligos containing the CpG methylation 5' to the Sp1 binding site. These results demonstrate a direct link between C/EBPdelta gene promoter hyper- and site specific-methylation and reduced C/EBPdelta gene expression in breast cancer cell lines and primary breast tumors.
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Affiliation(s)
- D Tang
- Department of Veterinary Biosciences and Ohio State Comprehensive Cancer Center, Ohio State University, Columbus, Ohio 43210, USA
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36
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Tan EH, Hooi SC, Laban M, Wong E, Ponniah S, Wee A, Wang ND. CCAAT/Enhancer Binding Protein α Knock-in Mice Exhibit Early Liver Glycogen Storage and Reduced Susceptibility to Hepatocellular Carcinoma. Cancer Res 2005; 65:10330-7. [PMID: 16288022 DOI: 10.1158/0008-5472.can-04-4486] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The CCAAT/enhancer binding protein alpha (C/EBPalpha) is vital for establishing normal hepatic energy homeostasis and moderating hepatocellular growth. CEBPA loss-of-function mutations identified in acute myeloid leukemia patients support a tumor suppressor role for C/EBPalpha. Recent work showed reductions of C/EBPalpha levels in human hepatocellular carcinoma with the reductions correlating to tumor size and progression. We investigated the potential of reactivating c/ebpalpha expression during hepatic carcinogenesis to prevent tumor cell growth. We have developed a c/ebpalpha knock-in mouse in which a single-copy c/ebpalpha is regulated by one allele of the alpha-fetoprotein (AFP) gene promoter. The knock-in mice are physically indistinguishable from wild-type (WT) controls. However, knock-in animals were found to deposit fetal hepatic glycogen earlier than WT animals. Quantitative real-time PCR confirmed early c/ebpalpha expression and early glycogen synthase gene activation in knock-in fetuses. We then used diethylnitrosamine to induce hepatocellular carcinoma in our animals. Diethylnitrosamine produced half the number of hepatocellular nodules in knock-in mice as in WT mice. Immunohistochemistry showed reduced C/EBPalpha content in WT nodules whereas knock-in nodules stained strongly for C/EBPalpha. The p21 protein was examined because it mediates a C/EBPalpha growth arrest pathway. Nuclear p21 was absent in WT nodules whereas cytoplasmic p21 was abundant; knock-in nodules were positive for nuclear p21. Interestingly, only C/EBPalpha-positive nodules were positive for nuclear p21, suggesting that C/EBPalpha may be required to direct p21 to the cell nucleus to inhibit growth. Our data establish that controlled C/EBPalpha production can inhibit liver tumor growth in vivo.
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Affiliation(s)
- Ee Hong Tan
- Department of Physiology, National University of Singapore, Singapore
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Steffen B, Müller-Tidow C, Schwäble J, Berdel WE, Serve H. The molecular pathogenesis of acute myeloid leukemia. Crit Rev Oncol Hematol 2005; 56:195-221. [PMID: 16236521 DOI: 10.1016/j.critrevonc.2004.10.012] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2004] [Revised: 09/30/2004] [Accepted: 10/28/2004] [Indexed: 10/25/2022] Open
Abstract
The description of the molecular pathogenesis of acute myeloid leukemias (AML) has seen dramatic progress over the last years. Two major types of genetic events have been described that are crucial for leukemic transformation: alterations in myeloid transcription factors governing hematopoietic differentiation and activating mutations of signal transduction intermediates. These processes are highly interdependent, since the molecular events changing the transcriptional control in hematopoietic progenitor cells modify the composition of signal transduction molecules available for growth factor receptors, while the activating mutations in signal transduction molecules induce alterations in the activity and expression of several transcription factors that are crucial for normal myeloid differentiation. The purpose of this article is to review the current literature describing these genetic events, their biological consequences and their clinical implications. As the article will show, the recent description of several critical transforming mutations in AML may soon give rise to more efficient and less toxic molecularly targeted therapies of this deadly disease.
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Affiliation(s)
- Björn Steffen
- Department of Medicine, Hematology/Oncology, University of Münster, Albert-Schweitzer-Strasse 33, 48129 Münster, Germany
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Turnbull EL, Martin IV, Fantes PA. Cdc37 maintains cellular viability in Schizosaccharomyces pombe independently of interactions with heat-shock protein 90. FEBS J 2005; 272:4129-40. [PMID: 16098195 DOI: 10.1111/j.1742-4658.2005.04825.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Cdc37 is a molecular chaperone that interacts with a range of clients and co-chaperones, forming various high molecular mass complexes. Cdc37 sequence homology among species is low. High homology between yeast and metazoan proteins is restricted to the extreme N-terminal region, which is known to bind clients that are predominantly protein kinases. We show that despite the low homology, both Saccharomyces cerevisiae and human Cdc37 are able to substitute for the Schizosaccharomyces pombe protein in a strain deleted for the endogenous cdc37 gene. Expression of a construct consisting of only the N-terminal domain of S. pombe Cdc37, lacking the postulated heat-shock protein (Hsp) 90-binding and homodimerization domains, can also sustain cellular viability, indicating that Cdc37 dimerization and interactions with the cochaperone Hsp90 may not be essential for Cdc37 function in S. pombe. Biochemical investigations showed that a small proportion of total cellular Cdc37 occurs in a high molecular mass complex that also contains Hsp90. These data indicate that the N-terminal domain of Cdc37 carries out essential functions independently of the Hsp90-binding domain and dimerization of the chaperone itself.
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Affiliation(s)
- Emma L Turnbull
- Institute of Cell Biology, School of Biological Sciences, University of Edinburgh, UK
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Shay KP, Wang Z, Xing PX, McKenzie IFC, Magnuson NS. Pim-1 kinase stability is regulated by heat shock proteins and the ubiquitin-proteasome pathway. Mol Cancer Res 2005; 3:170-81. [PMID: 15798097 DOI: 10.1158/1541-7786.mcr-04-0192] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Elevated expression of the serine/threonine kinase Pim-1 increases the incidence of lymphomas in Pim-1 transgenic mice and has also been found to occur in some human cancers. Pim-1 acts as a cell survival factor and may prevent apoptosis in malignant cells. It was therefore of interest to understand to what extent maintenance and degradation of Pim-1 protein is affected by heat shock proteins (Hsp) and the ubiquitin-proteasome pathway in K562 and BV173 human leukemic cells. The half-life of Pim-1 protein in these cells was found to increase from 1.7 to 3.1 hours when induced by heat shock or by treating the cells with the proteasome inhibitor PS-341 (bortezomib). The Hsp90 inhibitor geldanamycin prevented the stabilization of Pim-1 by heat shock. Using immunoprecipitation, it was determined that Pim-1 is targeted for degradation by ubiquitin and that Hsp70 is associated with Pim-1 under these circumstances. Conversely, Hsp90 was found to protect Pim-1 from proteasomal degradation. A luminescence-based kinase assay showed that Pim-1 kinase bound to Hsp70 or Hsp90 remains active, emphasizing the importance of its overall cellular levels. This study shows how Pim-1 levels can be modulated in cells through degradation and stabilization.
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Affiliation(s)
- Kate Petersen Shay
- School of Molecular Biosciences, Washington State University, Pullman, WA 99164-4234, USA
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Chin KT, Zhou HJ, Wong CM, Lee JMF, Chan CP, Qiang BQ, Yuan JG, Ng IOL, Jin DY. The liver-enriched transcription factor CREB-H is a growth suppressor protein underexpressed in hepatocellular carcinoma. Nucleic Acids Res 2005; 33:1859-73. [PMID: 15800215 PMCID: PMC1072803 DOI: 10.1093/nar/gki332] [Citation(s) in RCA: 81] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
We have previously characterized transcription factor LZIP to be a growth suppressor targeted by hepatitis C virus oncoprotein. In search of proteins closely related to LZIP, we have identified a liver-enriched transcription factor CREB-H. LZIP and CREB-H represent a new subfamily of bZIP factors. CREB-H activates transcription by binding to cAMP responsive element, box B, and ATF6-binding element. Interestingly, CREB-H has a putative transmembrane (TM) domain and it localizes ambiently to the endoplasmic reticulum. Proteolytic cleavage that removes the TM domain leads to nuclear translocation and activation of CREB-H. CREB-H activates the promoter of hepatic gluconeogenic enzyme phosphoenolpyruvate carboxykinase. This activation can be further stimulated by cAMP and protein kinase A. CREB-H transcript is exclusively abundant in adult liver. In contrast, the expression of CREB-H mRNA is aberrantly reduced in hepatoma tissues and cells. The enforced expression of CREB-H suppresses the proliferation of cultured hepatoma cells. Taken together, our findings suggest that the liver-enriched bZIP transcription factor CREB-H is a growth suppressor that plays a role in hepatic physiology and pathology.
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Affiliation(s)
- King-Tung Chin
- Department of Biochemistry, University of Hong KongHong Kong, China
| | - Hai-Jun Zhou
- Department of Biochemistry, University of Hong KongHong Kong, China
- National Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and Peking Union Medical CollegeBeijing 100005, China
| | - Chun-Ming Wong
- Department of Pathology, Faculty of Medicine, University of Hong KongHong Kong, China
| | - Joyce Man-Fong Lee
- Department of Pathology, Faculty of Medicine, University of Hong KongHong Kong, China
| | - Ching-Ping Chan
- Department of Biochemistry, University of Hong KongHong Kong, China
| | - Bo-Qin Qiang
- National Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and Peking Union Medical CollegeBeijing 100005, China
| | - Jian-Gang Yuan
- National Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and Peking Union Medical CollegeBeijing 100005, China
| | - Irene Oi-lin Ng
- Department of Pathology, Faculty of Medicine, University of Hong KongHong Kong, China
| | - Dong-Yan Jin
- Department of Biochemistry, University of Hong KongHong Kong, China
- To whom correspondence should be addressed at Department of Biochemistry, The University of Hong Kong, 3rd Floor, Laboratory Block, Faculty of Medicine Building, 21 Sassoon Road, Hong Kong. Tel: +852 2819 9491; Fax: +852 2855 1254;
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Timchenko NA, Wang GL, Timchenko LT. RNA CUG-binding protein 1 increases translation of 20-kDa isoform of CCAAT/enhancer-binding protein beta by interacting with the alpha and beta subunits of eukaryotic initiation translation factor 2. J Biol Chem 2005; 280:20549-57. [PMID: 15788409 DOI: 10.1074/jbc.m409563200] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Expression of a dominant negative 20-kDa isoform of CCAAT/enhancer-binding protein (C/EBPbeta), LIP, is increased in proliferating livers and in tumor cells. Two RNA-binding proteins, CUGBP1 and calreticulin, have been implicated in the translational regulation of C/EBPbeta. In this paper, we present evidence showing several critical steps by which liver increases translation of LIP after partial hepatectomy. At early stages after partial hepatectomy, liver activates CUGBP1 by a hyperphosphorylation. The activated CUGBP1 binds to the 5' region of C/EBPbeta mRNA and replaces calreticulin, which partially represses translation of C/EBPbeta in quiescent livers. The hyperphosphorylated CUGBP1 also interacts with the alpha and beta subunits of initiation factor eIF2. Our data demonstrate that the interaction of CUGBP1 with the eIF2alpha enhances the association of CUGBP1 with ribosomes and correlates with increased translation of LIP in the liver after partial hepatectomy. Our data support the hypothesis that CUGBP1 increases translation of LIP by the interaction with the eIF2alpha subunit. This facilitates subsequent recruitment of larger numbers of ribosomes to initiate translation of LIP.
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Affiliation(s)
- Nikolai A Timchenko
- Department of Pathology and Huffington Center on Aging, Baylor College of Medicine, Houston, Texas 77030, USA
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42
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Wang GL, Timchenko NA. Dephosphorylated C/EBPalpha accelerates cell proliferation through sequestering retinoblastoma protein. Mol Cell Biol 2005; 25:1325-38. [PMID: 15684384 PMCID: PMC548025 DOI: 10.1128/mcb.25.4.1325-1338.2005] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
CCAAT/enhancer-binding protein alpha (C/EBPalpha) has been previously considered a strong inhibitor of cell proliferation which uses multiple pathways to cause growth arrest. In this paper, we describe a new function of C/EBPalpha, which is an acceleration of cell proliferation. This new function of C/EBPalpha is created in proliferating livers by protein phosphatase 2A-mediated dephosphorylation of C/EBPalpha at Ser193. The Ser193-dephosphorylated C/EBPalpha interacts with retinoblastoma protein (Rb) independently on E2Fs and sequesters Rb, leading to a reduction of E2F-Rb repressors and to acceleration of proliferation. This new function of C/EBPalpha requires Rb, since the dephosphorylated C/EBPalpha does not promote proliferation in Rb-negative cells. We also show that a balance of Rb and Ser193-dephosphorylated C/EBPalpha determines if the cells are growth arrested or have an increased rate of proliferation. Consistently with these findings, a significant portion of Rb is sequestered into Rb-C/EBPalpha complexes in proliferating livers, and E2F-Rb complexes are not detectable in these livers. Our data demonstrate a new pathway by which the phosphorylation-dependent switch of biological functions of C/EBPalpha promotes liver proliferation.
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Affiliation(s)
- Guo-Li Wang
- Department of Pathology and Huffington Center on Aging, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA
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43
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Huang GC, Zhang JS, Tang QQ. Involvement of C/EBP-alpha gene in in vitro activation of rat hepatic stellate cells. Biochem Biophys Res Commun 2005; 324:1309-18. [PMID: 15504357 DOI: 10.1016/j.bbrc.2004.09.196] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2004] [Indexed: 02/07/2023]
Abstract
Hepatic stellate cells (HSCs) play key roles in hepatic fibrosis. One of the most striking alterations in activated HSCs is loss of cytoplasmic lipid droplets. However, the association of lipid storage with the activation of HSCs remains unclear. CCAAT/enhancer-binding proteins family (C/EBPs), especially C/EBP-alpha, controls differentiation of adipocytes. We suggested that C/EBP-alpha gene may be involved in HSCs activation. The present results showed that the expression levels of C/EBP-alpha and C/EBP-beta genes declined in activated HSCs. Over-expression of C/EBP-alpha gene in activated HSCs: (1) inhibited HSCs proliferation, extracellular matrix-producing, alpha-smooth muscle actin gene expression, and induced rebound of cytoplasmic lipid droplets; (2) reduced retinoic acid receptor-beta, C/EBP-delta and -beta gene expressions, but increased the active form C/EBP-beta PSer(105), and induced retinoid X receptor-alpha gene expression; and (3) did not affect the protein level of p16INK4a, p21Cip1/WAF1 or p27Kip1. In conclusions, C/EBP-alpha gene is involved in in vitro activation of rat HSCs.
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Affiliation(s)
- Guang-Cun Huang
- Department of Pathology, Shanghai Medical College, Fudan University, Shanghai 200032, PR China
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Schrem H, Klempnauer J, Borlak J. Liver-enriched transcription factors in liver function and development. Part II: the C/EBPs and D site-binding protein in cell cycle control, carcinogenesis, circadian gene regulation, liver regeneration, apoptosis, and liver-specific gene regulation. Pharmacol Rev 2004; 56:291-330. [PMID: 15169930 DOI: 10.1124/pr.56.2.5] [Citation(s) in RCA: 169] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
In the first part of our review (see Pharmacol Rev 2002;54:129-158), we discussed the basic principles of gene transcription and the complex interactions within the network of hepatocyte nuclear factors, coactivators, ligands, and corepressors in targeted liver-specific gene expression. Now we summarize the role of basic region/leucine zipper protein family members and particularly the albumin D site-binding protein (DBP) and the CAAT/enhancer-binding proteins (C/EBPs) for their importance in liver-specific gene expression and their role in liver function and development. Specifically, regulatory networks and molecular interactions were examined in detail, and the experimental findings summarized in this review point to pivotal roles of DBP and C/EBPs in cell cycle control, carcinogenesis, circadian gene regulation, liver regeneration, apoptosis, and liver-specific gene regulation. These regulatory proteins are therefore of great importance in liver physiology, liver disease, and liver development. Furthermore, interpretation of the vast data generated by novel genomic platform technologies requires a thorough understanding of regulatory networks and particularly the hierarchies that govern transcription and translation of proteins as well as intracellular protein modifications. Thus, this review aims to stimulate discussions on directions of future research and particularly the identification of molecular targets for pharmacological intervention of liver disease.
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Affiliation(s)
- Harald Schrem
- Center for Drug Research and Medical Biotechnology, Fraunhofer Institut für Toxikologie und Experimentelle Medizin, Nicolai Fuchs Str. 1, 30625 Hannover, Germany
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Abstract
Endoplasmic reticulum (ER) is the site of synthesis and folding of secretory proteins. Perturbations of ER homeostasis affect protein folding and cause ER stress. ER can sense the stress and respond to it through translational attenuation, upregulation of the genes for ER chaperones and related proteins, and degradation of unfolded proteins by a quality-control system. However, when the ER function is severely impaired, the organelle elicits apoptotic signals. ER stress has been implicated in a variety of common diseases such as diabetes, ischemia and neurodegenerative disorders. One of the components of the ER stress-mediated apoptosis pathway is C/EBP homologous protein (CHOP), also known as growth arrest- and DNA damage-inducible gene 153 (GADD153). Here, we summarize the current understanding of the roles of CHOP/GADD153 in ER stress-mediated apoptosis and in diseases including diabetes, brain ischemia and neurodegenerative disease.
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Affiliation(s)
- S Oyadomari
- Department of Molecular Genetics, Graduate School of Medical Sciences, Kumamoto University, Kumamoto 860-8556, Japan.
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Ogasawara T, Kawaguchi H, Jinno S, Hoshi K, Itaka K, Takato T, Nakamura K, Okayama H. Bone morphogenetic protein 2-induced osteoblast differentiation requires Smad-mediated down-regulation of Cdk6. Mol Cell Biol 2004; 24:6560-8. [PMID: 15254224 PMCID: PMC444857 DOI: 10.1128/mcb.24.15.6560-6568.2004] [Citation(s) in RCA: 103] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Because a temporal arrest in the G(1) phase of the cell cycle is thought to be a prerequisite for cell differentiation, we investigated cell cycle factors that critically influence the differentiation of mouse osteoblastic MC3T3-E1 cells induced by bone morphogenetic protein 2 (BMP-2), a potent inducer of osteoblast differentiation. Of the G(1) cell cycle factors examined, the expression of cyclin-dependent kinase 6 (Cdk6) was found to be strongly down-regulated by BMP-2/Smads signaling, mainly via transcriptional repression. The enforced expression of Cdk6 blocked BMP-2-induced osteoblast differentiation to various degrees, depending on the level of its overexpression. However, neither BMP-2 treatment nor Cdk6 overexpression significantly affected cell proliferation, suggesting that the inhibitory effect of Cdk6 on cell differentiation was exerted by a mechanism that is largely independent of its cell cycle regulation. These results indicate that Cdk6 is a critical regulator of BMP-2-induced osteoblast differentiation and that its Smads-mediated down-regulation is essential for efficient osteoblast differentiation.
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Affiliation(s)
- Toru Ogasawara
- Department of Biochemistry and Molecular Biology, Graduate School and Faculty of Medicine, University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-0033, Japan
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Li YH, Tao PZ, Liu YZ, Jiang JD. Geldanamycin, a ligand of heat shock protein 90, inhibits the replication of herpes simplex virus type 1 in vitro. Antimicrob Agents Chemother 2004; 48:867-72. [PMID: 14982777 PMCID: PMC353133 DOI: 10.1128/aac.48.3.867-872.2004] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Geldanamycin (GA) is an antibiotic targeting the ADP/ATP binding site of heat shock protein 90 (Hsp90). In screening for anti-herpes simplex virus type 1 (HSV-1) candidates, we found GA active against HSV-1. HSV-1 replication in vitro was significantly inhibited by GA with an 50% inhibitory concentration of 0.093 microM and a concentration that inhibited cellular growth 50% in comparison with the results seen with untreated controls of 350 microM. The therapeutic index of GA was over 3700 (comparable to the results seen with acyclovir). GA did not inhibit HSV-1 thymidine kinase. Cells infected with HSV-1 demonstrated cell cycle arrest at the G(1)/S transition; however, treatment with GA resulted in a cell cycle distribution pattern identical to that of untreated cells, indicating a restoration of cell growth in HSV-1-infected cells by GA treatment. Accordingly, HSV-1 DNA synthesis was suppressed in HSV-1(+) cells treated with GA. The antiviral mechanism of GA appears to be associated with Hsp90 inactivation and cell cycle restoration, which indicates that GA exhibits broad-spectrum antiviral activity. Indeed, GA exhibited activities in vitro against other viruses, including severe acute respiratory syndrome coronavirus. Since GA inhibits HSV-1 through a cellular mechanism unique among HSV-1 agents, we consider it a new candidate agent for HSV-1.
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Affiliation(s)
- Yu-Huan Li
- Laboratory of Antiviral Research, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100050, People's Republic of China
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48
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Wang GL, Iakova P, Wilde M, Awad S, Timchenko NA. Liver tumors escape negative control of proliferation via PI3K/Akt-mediated block of C/EBP alpha growth inhibitory activity. Genes Dev 2004; 18:912-25. [PMID: 15107404 PMCID: PMC395850 DOI: 10.1101/gad.1183304] [Citation(s) in RCA: 113] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2003] [Accepted: 03/15/2004] [Indexed: 01/10/2023]
Abstract
Liver tumor cells arise from normal hepatocytes that escape negative control of proliferation. The transcription factor C/EBPalpha maintains quiescence of hepatocytes through two pathways: inhibition of cdks and repression of E2F. Nevertheless, liver tumors and cultured hepatoma cell lines proliferate in the presence of C/EBPalpha. In this paper, we present evidence that the activation of the PI3K/Akt pathway in liver tumor cells blocks the growth inhibitory activity of C/EBPalpha through the PP2A-mediated dephosphorylation of C/EBPalpha on Ser 193, leading to a failure of C/EBPalpha to interact with and inhibit cdks and E2F. Mutation of Ser 193 to Ala also abolishes the ability of C/EBPalpha to cause growth arrest because of a lack of interactions with cdk2 and E2F-Rb complexes. These data provide a molecular basis for the development of liver tumors in which the activation of PI3K/Akt pathway neutralizes C/EBPalpha growth inhibitory activity.
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Affiliation(s)
- Guo-Li Wang
- Huffington Center on Aging and Department of Pathology, and Michael E. DeBakey Department of Surgery, Baylor College of Medicine, Houston, TX 77030, USA
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Abstract
Cdc37 is a relatively poorly conserved and yet essential molecular chaperone. It has long been thought to function primarily as an accessory factor for Hsp90, notably directing Hsp90 to kinases as substrates. More recent discoveries challenge this simplistic view. Cdc37 client proteins other than kinases have now been found, and Cdc37 displays a variety of Hsp90-independent activities both in vitro and in vivo. It can function as a molecular chaperone by itself, interact with other Hsp90 cochaperones in the absence of Hsp90, and even support yeast growth and protein folding without its Hsp90-binding domain. Thus, for many substrates, there may be many alternative chaperone pathways involving Cdc37, Hsp90, or both.
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Affiliation(s)
- Morag MacLean
- Département de Biologie Cellulaire, Université de Genève, Sciences III, 30, quai Ernest-Ansermet, CH-1211 Genève 4, Switzerland
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50
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Huang AM, Montagna C, Sharan S, Ni Y, Ried T, Sterneck E. Loss of CCAAT/enhancer binding protein delta promotes chromosomal instability. Oncogene 2004; 23:1549-57. [PMID: 14716301 DOI: 10.1038/sj.onc.1207285] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The transcription factor CCAAT/enhancer binding protein delta (Cebpd, also known as C/EBPdelta, CRP3, CELF, NF-IL6beta) is implicated in diverse cellular functions such as the acute phase response, adipocyte differentiation, learning and memory, and mammary epithelial cell growth control. Here, we report that lack of Cebpd causes genomic instability and centrosome amplifications in primary embryonic fibroblasts derived from 129S1 mice. Upon spontaneous immortalization, Cebpd-deficient fibroblasts acquire transformed features such as impaired contact inhibition and reduced serum dependence. These data identify a novel role for Cebpd in the maintenance of chromosomal stability and suggest a potential tumor suppressor function in vivo.
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Affiliation(s)
- A-Mei Huang
- Regulation of Cell Growth Laboratory, PO Box B, Frederick, MD 21702, USA
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