1
|
Meng W, Xiao H, Mei P, Chen J, Wang Y, Zhao R, Liao Y. Critical Roles of METTL3 in Translation Regulation of Cancer. Biomolecules 2023; 13:biom13020243. [PMID: 36830614 PMCID: PMC9953158 DOI: 10.3390/biom13020243] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2022] [Revised: 01/22/2023] [Accepted: 01/24/2023] [Indexed: 01/31/2023] Open
Abstract
Aberrant translation, a characteristic feature of cancer, is regulated by the complex and sophisticated RNA binding proteins (RBPs) in the canonical translation machinery. N6-methyladenosine (m6A) modifications are the most abundant internal modifications in mRNAs mediated by methyltransferase-like 3 (METTL3). METTL3 is commonly aberrantly expressed in different tumors and affects the mRNA translation of many oncogenes or dysregulated tumor suppressor genes in a variety of ways. In this review, we discuss the critical roles of METTL3 in translation regulation and how METTL3 and m6A reader proteins in collaboration with RBPs within the canonical translation machinery promote aberrant translation in tumorigenesis, providing an overview of recent efforts aiming to 'translate' these results to the clinic.
Collapse
Affiliation(s)
- Wangyang Meng
- Department of Thoracic Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
- Department of Thoracic Surgery, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200000, China
| | - Han Xiao
- Department of Thoracic Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
| | - Peiyuan Mei
- Department of Thoracic Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
| | - Jiaping Chen
- Department of Thoracic Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
| | - Yangwei Wang
- Department of Thoracic Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
| | - Rong Zhao
- Department of Thoracic Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
| | - Yongde Liao
- Department of Thoracic Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
- Correspondence:
| |
Collapse
|
2
|
Gotoh-Saito S, Sadato D, Shibasaki F. INT6/eIF3e represses E-cadherin expression through HIF2α in lung carcinoma A549 cells. Genes Cells 2022; 27:689-705. [PMID: 36116043 DOI: 10.1111/gtc.12984] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2022] [Revised: 09/14/2022] [Accepted: 09/15/2022] [Indexed: 12/13/2022]
Abstract
Hypoxia-inducible factor 2 α (HIF2α), a transcription factor playing a vital role in hypoxia, promotes cancer metastasis. We had previously reported that the cancer-related gene integration site 6/eukaryotic translation initiation factor 3 subunit e (INT6/eIF3e) negatively regulates the protein stability of HIF2α in an oxygen-independent manner. Presently, the downstream targets for INT6/eIF3e-regulated HIF2α are unknown. Given the roles of HIF2α and INT6/eIF3e in epithelial-mesenchymal transition (EMT) that promotes cancer metastasis, we hypothesized that INT6/eIF3e-regulated HIF2α controls EMT. This study shows that INT6/eIF3e knockdown in lung carcinoma A549 cells led to increased expression of HIF2α protein and an EMT-like phenotypic change. The increased HIF2α subsequently repressed the E-cadherin gene. Mechanistically, HIF2α interacts with the twist family bHLH transcription factor 1 (TWIST1) known to regulate EMT process, and binds to the proximal promoter region of E-cadherin, repressing it. Collectively, our work demonstrates that HIF2α, regulated by INT6/eIF3e, represses the E-cadherin gene through TWIST1 to enhance EMT, suggesting a role of the INT6/eIF3e-HIF2α axis in cancer metastasis.
Collapse
Affiliation(s)
- Saki Gotoh-Saito
- Department of Molecular Medical Research, Tokyo Metropolitan Institute of Medical Science, Tokyo, Japan
| | - Daichi Sadato
- Department of Molecular Medical Research, Tokyo Metropolitan Institute of Medical Science, Tokyo, Japan
| | - Futoshi Shibasaki
- Department of Molecular Medical Research, Tokyo Metropolitan Institute of Medical Science, Tokyo, Japan
| |
Collapse
|
3
|
Quan L, Jia C, Guo Y, Chen Y, Wang X, Xu Q, Zhang Y. HNRNPA2B1-mediated m6A modification of TLR4 mRNA promotes progression of multiple myeloma. J Transl Med 2022; 20:537. [PMID: 36401285 PMCID: PMC9673362 DOI: 10.1186/s12967-022-03750-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2022] [Accepted: 11/03/2022] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Multiple myeloma (MM) is a malignancy of plasma cells that remains incurable. Toll-like receptor 4 (TLR4) acts as a stress-responsive signal, protecting mitochondria during proteasome inhibitor (PI) exposure, maintaining mitochondrial metabolism and increasing drug resistance in MM. However, the mechanism of TLR4 regulation remains elusive. AIMS The purpose of this study was to investigate the methylation pattern of multiple myeloma and its effect on the expression of HNRNPA2B1 and downstream targets. METHODS The methylation level in MM and normal bone marrow specimens was detected using a colorimetric assay. HNRNPA2B1 gene knockdown was achieved in RPMI 8226 MM cells via adenovirus transfection. CCK8 and flow cytometric assays were used to detect proliferation and apoptosis, respectively. Transcriptome sequencing and m6A methylation MeRIP sequencing were applied, and differentially expressed genes (DEGs) were detected. Three independent NCBI GEO datasets were applied to examine the effects of HNRNPA2B1 and TLR4 expression on MM patient survival. RESULTS HNRNPA2B1 promoted MM progression. Clinical data from database revealed that HNRNPA2B1 was adverse prognostic factor for survival among MM patients. Furthermore, transcriptome sequencing and methylation sequencing showed that HNRNPA2B1 recognized and was enriched at the m6A sites of TLR4 and TLR4 was down-regulated of both the m6A level and transcription level in HNRNPA2B1-knockdown MM cells. Moreover, TLR4 was an adverse survival prognostic factor based on database analysis. CONCLUSION Overall, our study implies that the RNA-binding protein HNRNPA2B1 increases cell proliferation and deregulates cell apoptosis in MM through TLR4 signaling. Our study suggests HNRNPA2B1 as a potential therapeutic target for MM.
Collapse
Affiliation(s)
- Lina Quan
- grid.412651.50000 0004 1808 3502Hematology Department, Harbin Medical University Cancer Hospital, Harbin, Heilongjiang People’s Republic of China ,grid.410736.70000 0001 2204 9268Immunology Department, Harbin Medical University, Harbin, Heilongjiang People’s Republic of China
| | - Chuiming Jia
- grid.412651.50000 0004 1808 3502Hematology Department, Harbin Medical University Cancer Hospital, Harbin, Heilongjiang People’s Republic of China ,grid.410736.70000 0001 2204 9268Immunology Department, Harbin Medical University, Harbin, Heilongjiang People’s Republic of China
| | - Yiwei Guo
- grid.412651.50000 0004 1808 3502Hematology Department, Harbin Medical University Cancer Hospital, Harbin, Heilongjiang People’s Republic of China ,grid.410736.70000 0001 2204 9268Immunology Department, Harbin Medical University, Harbin, Heilongjiang People’s Republic of China
| | - Yao Chen
- grid.412651.50000 0004 1808 3502Hematology Department, Harbin Medical University Cancer Hospital, Harbin, Heilongjiang People’s Republic of China ,grid.410736.70000 0001 2204 9268Immunology Department, Harbin Medical University, Harbin, Heilongjiang People’s Republic of China
| | - Xinya Wang
- grid.412651.50000 0004 1808 3502Hematology Department, Harbin Medical University Cancer Hospital, Harbin, Heilongjiang People’s Republic of China ,grid.410736.70000 0001 2204 9268Immunology Department, Harbin Medical University, Harbin, Heilongjiang People’s Republic of China
| | - Qiuting Xu
- grid.412651.50000 0004 1808 3502Hematology Department, Harbin Medical University Cancer Hospital, Harbin, Heilongjiang People’s Republic of China ,grid.410736.70000 0001 2204 9268Immunology Department, Harbin Medical University, Harbin, Heilongjiang People’s Republic of China
| | - Yu Zhang
- grid.412651.50000 0004 1808 3502Hematology Department, Harbin Medical University Cancer Hospital, Harbin, Heilongjiang People’s Republic of China ,grid.410736.70000 0001 2204 9268Immunology Department, Harbin Medical University, Harbin, Heilongjiang People’s Republic of China
| |
Collapse
|
4
|
Sadato D, Ono T, Gotoh-Saito S, Kajiwara N, Nomura N, Ukaji M, Yang L, Sakimura K, Tajima Y, Oboki K, Shibasaki F. Eukaryotic translation initiation factor 3 (eIF3) subunit e is essential for embryonic development and cell proliferation. FEBS Open Bio 2018; 8:1188-1201. [PMID: 30087825 PMCID: PMC6070656 DOI: 10.1002/2211-5463.12482] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2017] [Revised: 04/13/2018] [Accepted: 06/12/2018] [Indexed: 11/06/2022] Open
Abstract
Mammalian eukaryotic translation initiation factor 3 (eIF3) is the largest complex of the translation initiation factors. The eIF3 complex is comprised of thirteen subunits, which are named eIF3a to eIF3 m in most multicellular organisms. The eIF3e gene locus is one of the most frequent integration sites of mouse mammary tumor virus (MMTV), which induces mammary tumors in mice. MMTV-integration events result in the expression of C-terminal-truncated eIF3e proteins, leading to mammary tumor formation. We have shown that tumor formation can be partly caused by activation of hypoxia-inducible factor 2α. To investigate the function of eIF3e in mammals, we generated eIF3e-deficient mice. These eIF3e-/- mice are embryonically lethal, while eIF3e+/- mice are much smaller than wild-type mice. In addition, eIF3e+/- mouse embryonic fibroblasts (MEFs) contained reduced levels of eIF3a and eIF3c subunits and exhibited reduced cellular proliferation. These results suggest that eIF3e is essential for embryonic development in mice and plays a role in maintaining eIF3 integrity.
Collapse
Affiliation(s)
- Daichi Sadato
- Department of Molecular Medical Research Tokyo Metropolitan Institute of Medical Science Japan.,Department of Applied Biological Science Faculty of Science and Technology Tokyo University of Science Noda Chiba Japan
| | - Tomio Ono
- Center for Basic Technology Research Tokyo Metropolitan Institute of Medical Science Japan
| | - Saki Gotoh-Saito
- Department of Molecular Medical Research Tokyo Metropolitan Institute of Medical Science Japan
| | - Naoki Kajiwara
- Department of Molecular Medical Research Tokyo Metropolitan Institute of Medical Science Japan
| | - Namiko Nomura
- Department of Molecular Medical Research Tokyo Metropolitan Institute of Medical Science Japan
| | - Masako Ukaji
- Department of Molecular Medical Research Tokyo Metropolitan Institute of Medical Science Japan
| | - Liying Yang
- Center for Basic Technology Research Tokyo Metropolitan Institute of Medical Science Japan
| | - Kenji Sakimura
- Department of Cellular Neurobiology Brain Research Institute Niigata University Japan
| | - Youichi Tajima
- Department of Molecular Medical Research Tokyo Metropolitan Institute of Medical Science Japan
| | - Keisuke Oboki
- Department of Molecular Medical Research Tokyo Metropolitan Institute of Medical Science Japan
| | - Futoshi Shibasaki
- Department of Molecular Medical Research Tokyo Metropolitan Institute of Medical Science Japan
| |
Collapse
|
5
|
Yin Y, Long J, Sun Y, Li H, Jiang E, Zeng C, Zhu W. The function and clinical significance of eIF3 in cancer. Gene 2018; 673:130-133. [PMID: 29908282 DOI: 10.1016/j.gene.2018.06.034] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2018] [Revised: 06/09/2018] [Accepted: 06/11/2018] [Indexed: 11/15/2022]
Abstract
Abnormal regulation of gene expression is essential for tumorigenesis. Several studies indicate that regulation of oncogene expression and neoplastic transformation are controlled by subunits of eukaryotic translation initiation factors (eIFs). Eukaryotic translation initiation factor 3 (eIF3) is the largest (800 kDa) and the most complex mammalian initiation factor. It is composed of 13 non-identical polypeptides designated as eIF3a-m and plays a pivotal role in protein synthesis that bridges the 43S pre-initiation complex and eIF4F-bound mRNA. However, the functional roles of individual subunits are not yet very clear. This review presents on several of aberrant expressed eIF3 subunits which are detected in various human cancers and the associated mechanisms have been acknowledged or are still not sure. Finally, identifying novel targets and biomarkers for caner is of great importance in early diagnosis and treatment of cancer. eIF3 may be a novel target molecule in drug development for cancer treatment and prevention.
Collapse
Affiliation(s)
- Yuting Yin
- Department of Pathology, School of Basic Medicine, Guangdong Medical University, Dongguan 523808, Guangdong Province, China
| | - Jiali Long
- Department of Pathology, School of Basic Medicine, Guangdong Medical University, Dongguan 523808, Guangdong Province, China
| | - Yanqin Sun
- Department of Pathology, School of Basic Medicine, Guangdong Medical University, Dongguan 523808, Guangdong Province, China
| | - Hongmei Li
- Department of Pathology, School of Basic Medicine, Guangdong Medical University, Dongguan 523808, Guangdong Province, China
| | - Enping Jiang
- Department of Pathology, School of Basic Medicine, Guangdong Medical University, Dongguan 523808, Guangdong Province, China
| | - Chao Zeng
- Department of Pathology, School of Basic Medicine, Guangdong Medical University, Dongguan 523808, Guangdong Province, China.
| | - Wei Zhu
- Department of Pathology, School of Basic Medicine, Guangdong Medical University, Dongguan 523808, Guangdong Province, China.
| |
Collapse
|
6
|
Abstract
The eukaryotic initiation factor 3 (eIF3) is one of the most complex translation initiation factors in mammalian cells, consisting of several subunits (eIF3a to eIF3m). It is crucial in translation initiation and termination, and in ribosomal recycling. Accordingly, deregulated eIF3 expression is associated with different pathological conditions, including cancer. In this manuscript, we discuss the interactome and function of each subunit of the human eIF3 complex. Furthermore, we review how altered levels of eIF3 subunits correlate with neurodegenerative disorders and cancer onset and development; in addition, we evaluate how such misregulation may also trigger infection cascades. A deep understanding of the molecular mechanisms underlying eIF3 role in human disease is essential to develop new eIF3-targeted therapeutic approaches and thus, overcome such conditions.
Collapse
Affiliation(s)
- Andreia Gomes-Duarte
- a Department of Human Genetics , Instituto Nacional de Saúde Doutor Ricardo Jorge , Lisbon , Portugal.,b Gene Expression and Regulation Group, Biosystems & Integrative Sciences Institute (BioISI), Faculdade de Ciências , Universidade de Lisboa , Lisbon , Portugal
| | - Rafaela Lacerda
- a Department of Human Genetics , Instituto Nacional de Saúde Doutor Ricardo Jorge , Lisbon , Portugal.,b Gene Expression and Regulation Group, Biosystems & Integrative Sciences Institute (BioISI), Faculdade de Ciências , Universidade de Lisboa , Lisbon , Portugal
| | - Juliane Menezes
- a Department of Human Genetics , Instituto Nacional de Saúde Doutor Ricardo Jorge , Lisbon , Portugal.,b Gene Expression and Regulation Group, Biosystems & Integrative Sciences Institute (BioISI), Faculdade de Ciências , Universidade de Lisboa , Lisbon , Portugal
| | - Luísa Romão
- a Department of Human Genetics , Instituto Nacional de Saúde Doutor Ricardo Jorge , Lisbon , Portugal.,b Gene Expression and Regulation Group, Biosystems & Integrative Sciences Institute (BioISI), Faculdade de Ciências , Universidade de Lisboa , Lisbon , Portugal
| |
Collapse
|
7
|
Renda F, Pellacani C, Strunov A, Bucciarelli E, Naim V, Bosso G, Kiseleva E, Bonaccorsi S, Sharp DJ, Khodjakov A, Gatti M, Somma MP. The Drosophila orthologue of the INT6 onco-protein regulates mitotic microtubule growth and kinetochore structure. PLoS Genet 2017; 13:e1006784. [PMID: 28505193 PMCID: PMC5448806 DOI: 10.1371/journal.pgen.1006784] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2016] [Revised: 05/30/2017] [Accepted: 04/27/2017] [Indexed: 12/01/2022] Open
Abstract
INT6/eIF3e is a highly conserved component of the translation initiation complex that interacts with both the 26S proteasome and the COP9 signalosome, two complexes implicated in ubiquitin-mediated protein degradation. The INT6 gene was originally identified as the insertion site of the mouse mammary tumor virus (MMTV), and later shown to be involved in human tumorigenesis. Here we show that depletion of the Drosophila orthologue of INT6 (Int6) results in short mitotic spindles and deformed centromeres and kinetochores with low intra-kinetochore distance. Poleward flux of microtubule subunits during metaphase is reduced, although fluorescence recovery after photobleaching (FRAP) demonstrates that microtubules remain dynamic both near the kinetochores and at spindle poles. Mitotic progression is delayed during metaphase due to the activity of the spindle assembly checkpoint (SAC). Interestingly, a deubiquitinated form of the kinesin Klp67A (a putative orthologue of human Kif18A) accumulates near the kinetochores in Int6-depleted cells. Consistent with this finding, Klp67A overexpression mimics the Int6 RNAi phenotype. Furthermore, simultaneous depletion of Int6 and Klp67A results in a phenotype identical to RNAi of just Klp67A, which indicates that Klp67A deficiency is epistatic over Int6 deficiency. We propose that Int6-mediated ubiquitination is required to control the activity of Klp67A. In the absence of this control, excess of Klp67A at the kinetochore suppresses microtubule plus-end polymerization, which in turn results in reduced microtubule flux, spindle shortening, and centromere/kinetochore deformation. INT6 is an evolutionarily conserved gene originally identified as the insertion site of the mouse mammary tumor virus that causes tumors in mice. INT6 is downregulated in many human cancers, suggesting that it acts as tumor suppressor gene. The INT6 protein is involved in several biological processes, including translation and ubiquitin-mediated protein degradation. We performed RNA interference (RNAi) against the Drosophila homologue of INT6 (Int6) and analyzed the effects of Int6 depletion on mitotic cell division. We found that loss of Int6 results in short spindles, delayed progression though metaphase and abnormally shaped centromeres/kinetochores. We also found that Int6-depleted cells fail to degrade the kinesin Klp67A. This protein, known to attenuate polymerization of microtubule (MTs) plus ends, accumulated at the kinetochores in Int6-depleted cells. We propose that this condition affects MT growth at the kinetochore, which in turn results in centromere/kinetochore deformation and delays satisfaction of the mitotic checkpoint.
Collapse
Affiliation(s)
- Fioranna Renda
- Dipartimento di Biologia e Biotecnologie “C. Darwin”, Sapienza, Università di Roma, Roma, Italy
- Wadsworth Center, New York State Department of Health, Albany, New York, United States of America
| | - Claudia Pellacani
- Dipartimento di Biologia e Biotecnologie “C. Darwin”, Sapienza, Università di Roma, Roma, Italy
- Istituto di Biologia e Patologia Molecolari (IBPM) del CNR, Roma, Italy
| | - Anton Strunov
- Institute of Molecular and Cellular Biology, Siberian Branch of RAS, Novosibirsk, Russia
- Institute of Cytology and Genetics, Siberian Branch of RAS, Novosibirsk, Russia
| | | | - Valeria Naim
- Dipartimento di Biologia e Biotecnologie “C. Darwin”, Sapienza, Università di Roma, Roma, Italy
| | - Giuseppe Bosso
- Dipartimento di Biologia e Biotecnologie “C. Darwin”, Sapienza, Università di Roma, Roma, Italy
| | - Elena Kiseleva
- Institute of Molecular and Cellular Biology, Siberian Branch of RAS, Novosibirsk, Russia
- Institute of Cytology and Genetics, Siberian Branch of RAS, Novosibirsk, Russia
| | - Silvia Bonaccorsi
- Dipartimento di Biologia e Biotecnologie “C. Darwin”, Sapienza, Università di Roma, Roma, Italy
| | - David J. Sharp
- Department of Physiology and Biophysics, Albert Einstein College of Medicine, Bronx, New York, United States of America
| | - Alexey Khodjakov
- Wadsworth Center, New York State Department of Health, Albany, New York, United States of America
| | - Maurizio Gatti
- Dipartimento di Biologia e Biotecnologie “C. Darwin”, Sapienza, Università di Roma, Roma, Italy
- Istituto di Biologia e Patologia Molecolari (IBPM) del CNR, Roma, Italy
- Institute of Molecular and Cellular Biology, Siberian Branch of RAS, Novosibirsk, Russia
- * E-mail: (MPS); (MG)
| | - Maria Patrizia Somma
- Istituto di Biologia e Patologia Molecolari (IBPM) del CNR, Roma, Italy
- * E-mail: (MPS); (MG)
| |
Collapse
|
8
|
Yin JY, Dong Z, Zhang JT. eIF3 Regulation of Protein Synthesis, Tumorigenesis, and Therapeutic Response. Methods Mol Biol 2017; 1507:113-127. [PMID: 27832536 DOI: 10.1007/978-1-4939-6518-2_9] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Translation initiation is the rate-limiting step of protein synthesis and highly regulated. Eukaryotic initiation factor 3 (eIF3) is the largest and most complex initiation factor consisting of 13 putative subunits. A growing number of studies suggest that eIF3 and its subunits may represent a new group of proto-oncogenes and associates with prognosis. They regulate translation of a subset of mRNAs involved in many cellular processes including proliferation, apoptosis, DNA repair, and cell cycle. Therefore, unveiling the mechanisms of eIF3 action in tumorigenesis may help identify attractive targets for cancer therapy. Here, we describe a series of methods used in the study of eIF3 function in regulating protein synthesis, tumorigenesis, and cellular response to therapeutic treatments.
Collapse
Affiliation(s)
- Ji-Ye Yin
- Department of Clinical Pharmacology, Xiangya Hospital, Central South University, 110 Xiang Ya Road, Changsha, Hunan, 410078, China.
| | - Zizheng Dong
- Department of Pharmacology and Toxicology and IU Simon Cancer Center, Indiana University School of Medicine, 980 W. Walnut Street, Indianapolis, IN, 46202, USA
| | - Jian-Ting Zhang
- Department of Pharmacology and Toxicology and IU Simon Cancer Center, Indiana University School of Medicine, 980 W. Walnut Street, Indianapolis, IN, 46202, USA.
| |
Collapse
|
9
|
Chu J, Cargnello M, Topisirovic I, Pelletier J. Translation Initiation Factors: Reprogramming Protein Synthesis in Cancer. Trends Cell Biol 2016; 26:918-933. [PMID: 27426745 DOI: 10.1016/j.tcb.2016.06.005] [Citation(s) in RCA: 78] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2016] [Revised: 06/03/2016] [Accepted: 06/13/2016] [Indexed: 12/11/2022]
Abstract
Control of mRNA translation plays a crucial role in the regulation of gene expression and is critical for cellular homeostasis. Dysregulation of translation initiation factors has been documented in several pathologies including cancer. Aberrant function of translation initiation factors leads to translation reprogramming that promotes proliferation, survival, angiogenesis, and metastasis. In such context, understanding how altered levels (and presumably activity) of initiation factors can contribute to tumor initiation and/or maintenance is of major interest for the development of novel therapeutic strategies. In this review we provide an overview of translation initiation mechanisms and focus on recent findings describing the role of individual initiation factors and their aberrant activity in cancer.
Collapse
Affiliation(s)
- Jennifer Chu
- Department of Biochemistry, McGill University, Montreal, Quebec, Canada
| | - Marie Cargnello
- Lady Davis Institute, SMBD JGH, McGill University, Montreal, Quebec, Canada; Gerald Bronfman Department of Oncology, McGill University, Quebec, Canada
| | - Ivan Topisirovic
- Department of Biochemistry, McGill University, Montreal, Quebec, Canada; Lady Davis Institute, SMBD JGH, McGill University, Montreal, Quebec, Canada; Gerald Bronfman Department of Oncology, McGill University, Quebec, Canada.
| | - Jerry Pelletier
- Department of Biochemistry, McGill University, Montreal, Quebec, Canada; Gerald Bronfman Department of Oncology, McGill University, Quebec, Canada; The Rosalind and Morris Goodman Cancer Research Centre, McGill University, Montreal, Quebec, Canada.
| |
Collapse
|
10
|
Assembly of eIF3 Mediated by Mutually Dependent Subunit Insertion. Structure 2016; 24:886-96. [PMID: 27210288 DOI: 10.1016/j.str.2016.02.024] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2016] [Revised: 02/19/2016] [Accepted: 02/21/2016] [Indexed: 02/05/2023]
Abstract
Eukaryotic initiation factor 3 (eIF3), an essential multi-protein complex involved in translation initiation, is composed of 12 tightly associated subunits in humans. While the overall structure of eIF3 is known, the mechanism of its assembly and structural consequences of dysregulation of eIF3 subunit expression seen in many cancers is largely unknown. Here we show that subunits in eIF3 assemble into eIF3 in an interdependent manner. Assembly of eIF3 is governed primarily by formation of a helical bundle, composed of helices extending C-terminally from PCI-MPN domains in eight subunits. We propose that, while the minimal subcomplex of human-like eIF3 functional for translation initiation in cells consists of subunits a, b, c, f, g, i, and m, numerous other eIF3 subcomplexes exist under circumstances of subunit over- or underexpression. Thus, eIF3 subcomplexes formed or "released" due to dysregulated subunit expression may be determining factors contributing to eIF3-related cancers.
Collapse
|
11
|
Zhou Z, Lu Q, Huang Q, Zheng C, Chen B, Lei Y. eIF3 regulates migration, invasion and apoptosis in cadmium transformed 16HBE cells and is a novel biomarker of cadmium exposure in a rat model and in workers. Toxicol Res (Camb) 2016; 5:761-772. [PMID: 30090387 PMCID: PMC6060694 DOI: 10.1039/c5tx00250h] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2015] [Accepted: 02/05/2016] [Indexed: 01/17/2023] Open
Abstract
Translation (eukaryotic) initiation factor 3 (eIF3 or TIF3) has been found to be a proto-oncogene in cadmium (Cd) response both in vitro and vivo, but whether eIF3 may serve as a biomarker of Cd exposure is still unclear. This study aimed to investigate whether eIF3 could serve as a novel biomarker of Cd toxicity in cells, animals and workers, and regulate the apoptosis, migration and invasion in human bronchial epithelial cell (16HBE cells) transformation with cadmium chloride (CdCl2). In CdCl2 transformed 16HBE cells, eIF3 expression increased gradually, and sequencing did not identify mutation and methylation of eIF3. In 16HBE cells with eIF3 silencing by siRNA and CdCl2 treated 16HBE cells of the 15th and 35th generations, the apoptosis, migration and invasion were significantly inhibited, and the expressions of relevant genes were also altered (P < 0.05). In CdCl2 treated rats, eIF3 mRNA expression increased to different extents in the blood, liver, kidney, heart and lung, and this increase was dependent on the Cd concentration (P < 0.05). The eIF3 mRNA expression was related to the mRNA expressions of AKT, BAX, BCL-2, E-CADHERIN, CASPASE-3, EGFR, FOXC2, STAT3, TGF-β1 and VIMENTIN (P < 0.05). In 181 workers with Cd exposure, the eIF3 mRNA expression was positively related to the blood Cd, urine Cd and β2-microglobulin content (P < 0.05). This study showed that abnormally expressed eIF3 may regulate the apoptosis, migration and invasion of 16HBE cells with Cd toxicity. This suggests that eIF3 may become a novel and valuable biomarker of Cd toxicity and Cd-induced effects, and may regulate apoptosis, migration and invasion of 16HBE cells. Thus, the detection of eIF3 expression is important for the monitoring of Cd toxicity in humans.
Collapse
Affiliation(s)
- Zhiheng Zhou
- School of Public Health , Guangzhou Medical University , Guangzhou 510182 , People's Republic of China .
| | - Qian Lu
- Shenzhen Longgang District Center for Disease Control & Prevention , Shenzhen 518172 , P.R. China
| | - Qinhai Huang
- School of Public Health , Guangzhou Medical University , Guangzhou 510182 , People's Republic of China .
| | - Chanjiao Zheng
- School of Public Health , Guangzhou Medical University , Guangzhou 510182 , People's Republic of China .
| | - Baoxin Chen
- School of Public Health , Guangzhou Medical University , Guangzhou 510182 , People's Republic of China .
| | - Yixiong Lei
- School of Public Health , Guangzhou Medical University , Guangzhou 510182 , People's Republic of China .
| |
Collapse
|
12
|
Hashimoto T, Shibasaki F. Hypoxia-inducible factor as an angiogenic master switch. Front Pediatr 2015; 3:33. [PMID: 25964891 PMCID: PMC4408850 DOI: 10.3389/fped.2015.00033] [Citation(s) in RCA: 149] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/13/2015] [Accepted: 04/07/2015] [Indexed: 12/19/2022] Open
Abstract
Hypoxia-inducible factors (HIFs) regulate the transcription of genes that mediate the response to hypoxia. HIFs are constantly expressed and degraded under normoxia, but stabilized under hypoxia. HIFs have been widely studied in physiological and pathological conditions and have been shown to contribute to the pathogenesis of various vascular diseases. In clinical settings, the HIF pathway has been studied for its role in inhibiting carcinogenesis. HIFs might also play a protective role in the pathology of ischemic diseases. Clinical trials of therapeutic angiogenesis after the administration of a single growth factor have yielded unsatisfactory or controversial results, possibly because the coordinated activity of different HIF-induced factors is necessary to induce mature vessel formation. Thus, manipulation of HIF activity to simultaneously induce a spectrum of angiogenic factors offers a superior strategy for therapeutic angiogenesis. Because HIF-2α plays an essential role in vascular remodeling, manipulation of HIF-2α is a promising approach to the treatment of ischemic diseases caused by arterial obstruction, where insufficient development of collateral vessels impedes effective therapy. Eukaryotic initiation factor 3 subunit e (eIF3e)/INT6 interacts specifically with HIF-2α and induces the proteasome inhibitor-sensitive degradation of HIF-2α, independent of hypoxia and von Hippel-Lindau protein. Treatment with eIF3e/INT6 siRNA stabilizes HIF-2α activity even under normoxic conditions and induces the expression of several angiogenic factors, at levels sufficient to produce functional arteries and veins in vivo. We have demonstrated that administration of eIF3e/INT6 siRNA to ischemic limbs or cold-injured brains reduces ischemic damage in animal models. This review summarizes the current understanding of the relationship between HIFs and vascular diseases. We also discuss novel oxygen-independent regulatory proteins that bind HIF-α and the implications of a new method for therapeutic angiogenesis using HIF stabilizers.
Collapse
Affiliation(s)
- Takuya Hashimoto
- Department of Surgery, Yale University School of Medicine , New Haven, CT , USA ; Division of Vascular Surgery, Department of Surgery, Graduate School of Medicine, The University of Tokyo , Tokyo , Japan
| | - Futoshi Shibasaki
- Department of Molecular Medical Research, Tokyo Metropolitan Institute of Medical Science , Tokyo , Japan
| |
Collapse
|
13
|
Hershey JWB. The role of eIF3 and its individual subunits in cancer. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2014; 1849:792-800. [PMID: 25450521 DOI: 10.1016/j.bbagrm.2014.10.005] [Citation(s) in RCA: 77] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/12/2014] [Revised: 10/28/2014] [Accepted: 10/28/2014] [Indexed: 12/15/2022]
Abstract
Specific individual subunits of eIF3 are elevated or reduced in numerous human tumors, and their ectopic overexpression in immortal cells can result in malignant transformation. The structure and assembly of eIF3 and its role in promoting mRNA and methionyl-tRNAi binding to the ribosome during the initiation phase of protein synthesis are described. Methods employed to detect altered levels of eIF3 subunits in cancers are critically evaluated in order to conclude rigorously that such subunits may cause malignant transformation. Strong evidence is presented that the individual overexpression of eIF3 subunits 3a, 3b, 3c, 3h, 3i and 3m may cause malignant transformation, whereas underexpression of subunits 3e and 3f may cause a similar outcome. Possible mechanisms to explain the malignant phenotypes are examined. The involvement of eIF3 in cancer reinforces the view that translational control plays an important role in the regulation of cell proliferation, and provides new targets for the development of therapeutic agents. This article is part of a Special Issue entitled: Translation and Cancer.
Collapse
Affiliation(s)
- John W B Hershey
- Department of Biochemistry and Molecular Medicine, University of California, Davis, CA 95616, United States.
| |
Collapse
|
14
|
Yong ZWE, Zaini ZM, Kallarakkal TG, Karen-Ng LP, Rahman ZAA, Ismail SM, Sharifah NA, Mustafa WMW, Abraham MT, Tay KK, Zain RB. Genetic alterations of chromosome 8 genes in oral cancer. Sci Rep 2014; 4:6073. [PMID: 25123227 PMCID: PMC4133705 DOI: 10.1038/srep06073] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2014] [Accepted: 06/27/2014] [Indexed: 12/13/2022] Open
Abstract
The clinical relevance of DNA copy number alterations in chromosome 8 were investigated in oral cancers. The copy numbers of 30 selected genes in 33 OSCC patients were detected using the multiplex ligation-dependent probe amplification (MLPA) technique. Amplifications of the EIF3E gene were found in 27.3% of the patients, MYC in 18.2%, RECQL4 in 15.2% and MYBL1 in 12.1% of patients. The most frequent gene losses found were the GATA4 gene (24.2%), FGFR1 gene (24.2%), MSRA (21.2) and CSGALNACT1 (12.1%). The co-amplification of EIF3E and RECQL4 was found in 9% of patients and showed significant association with alcohol drinkers. There was a significant association between the amplification of EIF3E gene with non-betel quid chewers and the negative lymph node status. EIF3E amplifications did not show prognostic significance on survival. Our results suggest that EIF3E may have a role in the carcinogenesis of OSCC in non-betel quid chewers.
Collapse
Affiliation(s)
- Zachary Wei Ern Yong
- 1] Department of Oro-Maxillofacial Surgical and Medical Sciences, Faculty of Dentistry, University of Malaya, Kuala Lumpur, Malaysia [2] Oral Cancer Research &Coordinating Centre (OCRCC), Faculty of Dentistry, University of Malaya, Kuala Lumpur, Malaysia
| | - Zuraiza Mohamad Zaini
- 1] Department of Oro-Maxillofacial Surgical and Medical Sciences, Faculty of Dentistry, University of Malaya, Kuala Lumpur, Malaysia [2] Oral Cancer Research &Coordinating Centre (OCRCC), Faculty of Dentistry, University of Malaya, Kuala Lumpur, Malaysia
| | - Thomas George Kallarakkal
- 1] Department of Oro-Maxillofacial Surgical and Medical Sciences, Faculty of Dentistry, University of Malaya, Kuala Lumpur, Malaysia [2] Oral Cancer Research &Coordinating Centre (OCRCC), Faculty of Dentistry, University of Malaya, Kuala Lumpur, Malaysia
| | - Lee Peng Karen-Ng
- Oral Cancer Research &Coordinating Centre (OCRCC), Faculty of Dentistry, University of Malaya, Kuala Lumpur, Malaysia
| | - Zainal Ariff Abdul Rahman
- 1] Department of Oro-Maxillofacial Surgical and Medical Sciences, Faculty of Dentistry, University of Malaya, Kuala Lumpur, Malaysia [2] Oral Cancer Research &Coordinating Centre (OCRCC), Faculty of Dentistry, University of Malaya, Kuala Lumpur, Malaysia
| | - Siti Mazlipah Ismail
- 1] Department of Oro-Maxillofacial Surgical and Medical Sciences, Faculty of Dentistry, University of Malaya, Kuala Lumpur, Malaysia [2] Oral Cancer Research &Coordinating Centre (OCRCC), Faculty of Dentistry, University of Malaya, Kuala Lumpur, Malaysia
| | - Noor Akmal Sharifah
- Department of Pathology, Universiti Kebangsaan Malaysia Medical Centre, Kuala Lumpur
| | | | - Mannil Thomas Abraham
- Department of Oral and Maxillofacial Surgery, Hospital Tengku Ampuan Rahimah, Klang, Malaysia
| | - Keng Kiong Tay
- Oral Surgery Clinic, Hospital Umum Sarawak, Kuching, Malaysia
| | - Rosnah Binti Zain
- 1] Department of Oro-Maxillofacial Surgical and Medical Sciences, Faculty of Dentistry, University of Malaya, Kuala Lumpur, Malaysia [2] Oral Cancer Research &Coordinating Centre (OCRCC), Faculty of Dentistry, University of Malaya, Kuala Lumpur, Malaysia
| |
Collapse
|
15
|
Abstract
Translation initiation plays a critical role in the regulation of cell growth and tumorigenesis. We report here that inhibiting translation initiation through induction of eIF2α phosphorylation by small-molecular-weight compounds restricts the availability of the eIF2·GTP·Met-tRNAi ternary complex and abrogates the proliferation of cancer cells in vitro and tumor growth in vivo. Restricting the availability of the ternary complex preferentially down-regulates the expression of growth-promoting proteins and up-regulates the expression of ER stress response genes in cancer cells as well as in tumors excised from either animal models of human cancer or cancer patients. These findings provide the first direct evidence for translational control of gene-specific expression by small molecules in vivo and indicate that translation initiation factors are bona fide targets for development of mechanism-specific anti-cancer agents.
Collapse
|
16
|
Walsh D, Mohr I. Coupling 40S ribosome recruitment to modification of a cap-binding initiation factor by eIF3 subunit e. Genes Dev 2014; 28:835-40. [PMID: 24736843 PMCID: PMC4003276 DOI: 10.1101/gad.236752.113] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Recruitment of ribosomes to the mRNA 5′ terminus involves the activity of a large number of functionally discrete eukaryotic translation initiation factors (eIFs). However, how multiple eIFs coordinate during translation initiation remains poorly understood. Walsh and Mohr now identify an eIF3 subunit that regulates eIF4F modification and show that eIF3e is required for inducible eIF4E phosphorylation. This study establishes a mechanism by which 40S ribosome loading imparts a phosphorylation mark on the cap-binding eIF4F complex that regulates selective mRNA translation. 40S ribosomes are loaded onto capped mRNAs via the multisubunit translation initiation factors eIF3 and eIF4F. While eIF4E is the eIF4F cap recognition component, the eIF4G subunit associates with 40S-bound eIF3. How this intricate process is coordinated remains poorly understood. Here, we identify an eIF3 subunit that regulates eIF4F modification and show that eIF3e is required for inducible eIF4E phosphorylation. Significantly, recruitment of the eIF4E kinase Mnk1 (MAPK signal-integrating kinase 1) to eIF4F depended on eIF3e, and eIF3e was sufficient to promote Mnk1-binding to eIF4G. This establishes a mechanism by which 40S ribosome loading imparts a phosphorylation mark on the cap-binding eIF4F complex that regulates selective mRNA translation and is synchronized by a specific eIF3 subunit.
Collapse
Affiliation(s)
- Derek Walsh
- Department of Microbiology, New York University School of Medicine, New York, New York 10016, USA
| | | |
Collapse
|
17
|
Eukaryotic translation initiation factors in cancer development and progression. Cancer Lett 2013; 340:9-21. [PMID: 23830805 DOI: 10.1016/j.canlet.2013.06.019] [Citation(s) in RCA: 113] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2013] [Revised: 06/11/2013] [Accepted: 06/14/2013] [Indexed: 01/03/2023]
Abstract
Eukaryotic gene expression is a complicated process primarily regulated at the levels of gene transcription and mRNA translation. The latter involves four main steps: initiation, elongation, termination and recycling. Translation regulation is primarily achieved during initiation which is orchestrated by 12 currently known eukaryotic initiation factors (eIFs). Here, we review the current state of eIF research and present a concise summary of the various eIF subunits. As eIFs turned out to be critically implicated in different oncogenic processes the various eIF members and their contribution to onset and progression of cancer are featured.
Collapse
|
18
|
Zheng L, Senda Y, Abe S. Perturbation in protein expression of the sterile salmonid hybrids between female brook trout Salvelinus fontinalis and male masu salmon Oncorhynchus masou during early spermatogenesis. Anim Reprod Sci 2013; 138:292-304. [DOI: 10.1016/j.anireprosci.2013.03.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2012] [Revised: 02/21/2013] [Accepted: 03/01/2013] [Indexed: 10/27/2022]
|
19
|
Wang H, Ru Y, Sanchez-Carbayo M, Wang X, Kieft JS, Theodorescu D. Translation initiation factor eIF3b expression in human cancer and its role in tumor growth and lung colonization. Clin Cancer Res 2013; 19:2850-60. [PMID: 23575475 DOI: 10.1158/1078-0432.ccr-12-3084] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
PURPOSE Discovery transcriptomic analyses suggest eukaryotic initiation factor 3b (eIF3b) is elevated in human bladder and prostate cancer, yet its role as a prognostic factor or its requirement in the maintenance or progression of human cancer is not established. Here, we determine the therapeutic potential of eIF3b by examining the clinical relevance of its expression in human cancer tissues and its role in experimental tumor models. EXPERIMENTAL DESIGN We examined mRNA expression of eIF3b in bladder (N = 317) and prostate (N = 566) tissue samples and protein expression by immunohistochemistry in 143 bladder tumor samples as a function of clinicopathologic features. The impact of eIF3b depletion by siRNA in human cancer lines was evaluated in regard to in vitro cell growth, cell cycle, migration, in vivo subcutaneous tumor growth, and lung colonization. RESULTS eIF3b mRNA expression correlated to tumor grade, stage, and survival in human bladder and prostate cancer. eIF3b protein expression stratified survival in human bladder cancer. eIF3b depletion reduced in vitro cancer cell growth; inhibited G1-S cell-cycle transition by changing protein but not RNA expression of cyclin A, E, Rb, and p27Kip1; inhibited migration; and disrupted actin cytoskeleton and focal adhesions. These changes were associated with decreased protein expression of integrin α5. Integrin α5 depletion phenocopied effects observed with eIF3b. eIF3b-depleted bladder cancer cells formed fewer subcutaneous tumors that grew more slowly and had reduced lung colonization. CONCLUSION eIF3b expression relates to human bladder and prostate cancer prognosis, is required for tumor growth, and thus a candidate therapeutic target.
Collapse
Affiliation(s)
- Hong Wang
- Department of Surgery (Urology), University of Colorado, Aurora, Colorado 80045, USA
| | | | | | | | | | | |
Collapse
|
20
|
Fung KYC, Ooi CC, Lewanowitsch T, Tan S, Tan HT, Lim TK, Lin Q, Williams DB, Lockett TJ, Cosgrove LJ, Chung MCM, Head RJ. Identification of Potential Pathways Involved in Induction of Apoptosis by Butyrate and 4-Benzoylbutyrate in HT29 Colorectal Cancer Cells. J Proteome Res 2012; 11:6019-29. [DOI: 10.1021/pr3007107] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Affiliation(s)
- Kim Y. C. Fung
- CSIRO Preventative Health National Research Flagship, Adelaide, Australia
- CSIRO Animal, Food and Health Sciences, Adelaide and North Ryde, Australia
| | - Cheng Cheng Ooi
- CSIRO Preventative Health National Research Flagship, Adelaide, Australia
- CSIRO Animal, Food and Health Sciences, Adelaide and North Ryde, Australia
- School of Pharmacy and Medical
Sciences, Sansom Institute for Health Research, University of South Australia, Australia
| | - Tanya Lewanowitsch
- CSIRO Preventative Health National Research Flagship, Adelaide, Australia
- CSIRO Animal, Food and Health Sciences, Adelaide and North Ryde, Australia
| | - Sandra Tan
- Department of Biological Sciences,
Faculty of Science, National University of Singapore, Singapore
| | - Hwee Tong Tan
- Department of Biochemistry, Yong Loo
Lin School of Medicine, National University of Singapore, Singapore
| | - Teck Kwang Lim
- Department of Biological Sciences,
Faculty of Science, National University of Singapore, Singapore
| | - Qingsong Lin
- Department of Biological Sciences,
Faculty of Science, National University of Singapore, Singapore
| | - Desmond B. Williams
- School of Pharmacy and Medical
Sciences, Sansom Institute for Health Research, University of South Australia, Australia
| | - Trevor J. Lockett
- CSIRO Preventative Health National Research Flagship, Adelaide, Australia
- CSIRO Animal, Food and Health Sciences, Adelaide and North Ryde, Australia
| | - Leah J. Cosgrove
- CSIRO Preventative Health National Research Flagship, Adelaide, Australia
- CSIRO Animal, Food and Health Sciences, Adelaide and North Ryde, Australia
| | - Maxey C. M. Chung
- Department of Biological Sciences,
Faculty of Science, National University of Singapore, Singapore
- Department of Biochemistry, Yong Loo
Lin School of Medicine, National University of Singapore, Singapore
| | - Richard J. Head
- CSIRO Preventative Health National Research Flagship, Adelaide, Australia
- CSIRO Animal, Food and Health Sciences, Adelaide and North Ryde, Australia
| |
Collapse
|
21
|
Abstract
Protein synthesis is a complex, tightly regulated process in eukaryotic cells and its deregulation is a hallmark of many cancers. Translational control occurs primarily at the rate-limiting initiation step, where ribosomal subunits are recruited to template mRNAs through the concerted action of several eukaryotic initiation factors (eIFs). One factor that interacts with both the mRNA and ribosomes, and appears limiting for translation is eIF4F, a complex composed of the cap-binding protein, eIF4E; the scaffold protein, eIF4G; and the ATP-dependent DEAD-box helicase, eIF4A. eIF4E appears to play an important role in tumor initiation and progression since its overexpression can cooperate with oncogenes to accelerate transformation in cell lines and animal models, and its levels are elevated in many human cancers. This, therefore, represents a vulnerability for transformed cells, and presents an opportunity for therapeutic intervention. In this review, we discuss approaches for targeting eIF4F activity.
Collapse
|
22
|
Wei L, Lei YX, Wu L, Wang M, Lu Q, He CC. Alterations in the expression of translation factors as molecular markers in cadmium-exposed workers. Biomarkers 2011; 17:78-84. [PMID: 22149723 DOI: 10.3109/1354750x.2011.639463] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Eukaryotic translation initiation factor 3 (eIF3) and elongation factor 1δ (eEF-1δ) are novel cadmium (Cd) responsive proto-oncogenes. This research investigated the expression of these genes in Cd-exposed workers (n = 58), and to evaluate their usefulness as biomarkers of Cd exposure. According to urinary Cd concentration, the subjects were divided into four groups (urinary Cd concentration ≥0.1 μg/g.Cr, ≥1.0 μg/g.Cr, ≥5.0 μg/g.Cr and ≥50.0 μg/g.Cr). Subjects exhibited increased severe health problems with higher urinary Cd concentrations. The eIF3 and eEF-1δ expression in the blood were investigated with real-time PCR. PCR data showed a strong positive correlation between blood eEF-1δ and urinary Cd concentrations (r = 0.788, p < 0.01), and a weak positive correlation between blood eIF3 expression and urinary Cd concentrations (r = 0.569, p < 0.05). These findings, for the first time, demonstrate that the blood eEF-1δ overexpression can be used as a molecular biomarker of Cd-exposed population.
Collapse
Affiliation(s)
- Lian Wei
- School of Public Health, Guangzhou Medical University, PR China
| | | | | | | | | | | |
Collapse
|
23
|
Translational control gone awry: a new mechanism of tumorigenesis and novel targets of cancer treatments. Biosci Rep 2011; 31:1-15. [PMID: 20964625 DOI: 10.1042/bsr20100077] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Translational control is one of primary regulation mechanisms of gene expression. Eukaryotic translational control mainly occurs at the initiation step, the speed-limiting step, which involves more than ten translation initiation factors [eIFs (eukaryotic initiation factors)]. Changing the level or function of these eIFs results in abnormal translation of specific mRNAs and consequently abnormal growth of cells that leads to human diseases, including cancer. Accumulating evidence from recent studies showed that the expression of many eIFs was associated with malignant transformation, cancer prognosis, as well as gene expression regulation. In the present paper, we perform a critical review of recent advances in understanding the role and mechanism of eIF action in translational control and cancer as well as the possibility of targeting eIFs for therapeutic development.
Collapse
|
24
|
Chiluiza D, Bargo S, Callahan R, Rhoads RE. Expression of truncated eukaryotic initiation factor 3e (eIF3e) resulting from integration of mouse mammary tumor virus (MMTV) causes a shift from cap-dependent to cap-independent translation. J Biol Chem 2011; 286:31288-96. [PMID: 21737453 DOI: 10.1074/jbc.m111.267294] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Integration of mouse mammary tumor virus (MMTV) at the common integration site Int6 occurs in the gene encoding eIF3e, the p48 subunit of translation initiation factor eIF3. Integration is at any of several introns of the Eif3e gene and causes the expression of truncated Eif3e mRNAs. Ectopic expression of the truncated eIF3e protein resulting from integration at intron 5 (3e5) induces malignant transformation, but by an unknown mechanism. Because eIF3e makes up at least part of the binding site for eIF4G, we examined the effects of 3e5 expression on protein synthesis. We developed an NIH3T3 cell line that contains a single copy of the 3e5 sequence at a predetermined genomic site. Co-immunoprecipitation indicated diminished binding of eIF3 to eIF4G, signifying a reduction in recruitment of the mRNA-unwinding machinery to the 43 S preinitiation complex. Cell growth and overall protein synthesis were decreased. Translation driven by the eIF4G-independent hepatitis C virus internal ribosome entry sequence (HCV IRES) in a bicistronic mRNA was increased relative to cap-dependent translation. Endogenous mRNAs encoding XIAP, c-Myc, CYR61, and Pim-1, which are translated in a cap-independent manner, were shifted to heavier polysomes whereas mRNAs encoding GAPDH, actin, L32, and L34, which are translated in a cap-dependent manner, were shifted to lighter polysomes. We propose that expression of 3e5 diminishes eIF4G interaction with eIF3 and causes abnormal gene expression at the translational level. The correlation between up-regulation of cap-independent translation and MMTV-induced tumorigenesis contrasts with the well established model for malignant transformation involving up-regulation of highly cap-dependent translation.
Collapse
Affiliation(s)
- David Chiluiza
- Department of Biochemistry and Molecular Biology, Louisiana State University Health Sciences Center, Shreveport, Louisiana 71106, USA
| | | | | | | |
Collapse
|
25
|
Nemoto N, Udagawa T, Ohira T, Jiang L, Hirota K, Wilkinson CRM, Bähler J, Jones N, Ohta K, Wek RC, Asano K. The roles of stress-activated Sty1 and Gcn2 kinases and of the protooncoprotein homologue Int6/eIF3e in responses to endogenous oxidative stress during histidine starvation. J Mol Biol 2010; 404:183-201. [PMID: 20875427 PMCID: PMC4378542 DOI: 10.1016/j.jmb.2010.09.016] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2010] [Revised: 08/31/2010] [Accepted: 09/08/2010] [Indexed: 01/21/2023]
Abstract
In fission yeast, Sty1 and Gcn2 are important protein kinases that regulate gene expression in response to amino acid starvation. The translation factor subunit Int6/eIF3e promotes Sty1-dependent response by increasing the abundance of Atf1, a transcription factor targeted by Sty1. While Gcn2 promotes expression of amino acid biosynthesis enzymes, the mechanism and function of Sty1 activation and Int6/eIF3e involvement during this nutrient stress are not understood. Here we show that mutants lacking sty1(+) or gcn2(+) display reduced viabilities during histidine depletion stress in a manner suppressible by the antioxidant N-acetyl cysteine, suggesting that these protein kinases function to alleviate endogenous oxidative damage generated during nutrient starvation. Int6/eIF3e also promotes cell viability by a mechanism involving the stimulation of Sty1 response to oxidative damage. In further support of these observations, microarray data suggest that, during histidine starvation, int6Δ increases the duration of Sty1-activated gene expression linked to oxidative stress due to the initial attenuation of Sty1-dependent transcription. Moreover, loss of gcn2 induces the expression of a new set of genes not activated in wild-type cells starved for histidine. These genes encode heatshock proteins, redox enzymes, and proteins involved in mitochondrial maintenance, in agreement with the idea that oxidative stress is imposed on gcn2Δ cells. Furthermore, early Sty1 activation promotes rapid Gcn2 activation on histidine starvation. These results suggest that Gcn2, Sty1, and Int6/eIF3e are functionally integrated and cooperate to respond to oxidative stress generated during histidine starvation.
Collapse
Affiliation(s)
- Naoki Nemoto
- Molecular Cellular and Developmental Biology Program, Division of Biology, Kansas State University, Manhattan, KS 66506, USA
| | - Tsuyoshi Udagawa
- Molecular Cellular and Developmental Biology Program, Division of Biology, Kansas State University, Manhattan, KS 66506, USA
| | - Takahiro Ohira
- Molecular Cellular and Developmental Biology Program, Division of Biology, Kansas State University, Manhattan, KS 66506, USA
| | - Li Jiang
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN 46202, USA
| | - Kouji Hirota
- Shibata distinguished scientist laboratory, RIKEN, Hirosawa 2-1, Wako-shi, Saitama 351-0198, Japan
| | - Caroline R. M. Wilkinson
- Cancer Research UK Cell Regulation Laboratory, Paterson Institute for Cancer Research, University of Manchester, Manchester M20 4BX, UK
| | - Jürg Bähler
- Department of Genetics, Evolution & Environment and UCL Cancer Institute, University College London, London WC1E 6BT, UK
| | - Nic Jones
- Cancer Research UK Cell Regulation Laboratory, Paterson Institute for Cancer Research, University of Manchester, Manchester M20 4BX, UK
| | - Kunihiro Ohta
- Department of Life Sciences, Graduated School of Arts and Sciences, University of Tokyo, Komaba 3-8-1, Meguroku, Tokyo 153-8902, JAPAN
| | - Ronald C. Wek
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN 46202, USA
| | - Katsura Asano
- Molecular Cellular and Developmental Biology Program, Division of Biology, Kansas State University, Manhattan, KS 66506, USA
| |
Collapse
|
26
|
Int6 regulates both proteasomal degradation and translation initiation and is critical for proper formation of acini by human mammary epithelium. Oncogene 2010; 30:724-36. [PMID: 20890303 PMCID: PMC3017639 DOI: 10.1038/onc.2010.445] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
INT6/EIF3E has been implicated in breast tumorigenesis, but its functional activities remain poorly defined. We found that repressing INT6 expression induced transformed properties in normal human mammary epithelium (MCF10A); in contrast, Int6 silencing induced apoptosis in HeLa cells. As in yeast, Int6 in human cells was required for assembly of active proteasomes. A reverse phase protein array screen identified SRC3/AIB1 as one oncoprotein whose level and stability increased when Int6 was silenced in MCF10A cells. Our data further show that Int6 binds SRC3 and its ubiquitin ligase Fbw7, thus perhaps mediating the interaction between SRC3-Fbw7 and proteasomes. Consistent with this, Int6 silencing did not increase SRC3 levels in HeLa cells, which have low Fbw7 levels. Surprisingly, however, polyubiquitylated proteins do not accumulate or may even decrease in Int6-silenced cells that contain defective proteasomes. Considering that decreased ubiquitin might explain this observation and that Int6 might control ubiquitin levels in its role as a subunit of eIF3 (eukaryote translation initiation factor), we found that silencing Int6 reduced monoubiquitin protein levels, which correlated with a shift of ubiquitin mRNAs from larger polysomes to non-translating ribosomes. In contrast, levels of many housekeeping proteins did not change. This apparent reduction in the translation of ubiquitin genes correlated with a modest reduction in protein synthesis rate and formation of large polysomes. To further determine whether Int6 can selectively control translation, we analyzed translation of different 5′-UTR reporters and found that indeed, loss of Int6 had differential effects on these reporters. Together the data suggest that Int6 depletion blocks ubiquitin-dependent proteolysis by decreasing both ubiquitin levels and the assembly of functional proteasome machinery, leading to accumulation of oncoproteins such as SRC3 that can transform mammary epithelium. Our data also raise the possibility that Int6 can further fine-tune protein levels by selectively controlling translation of specific mRNAs.
Collapse
|
27
|
Saletta F, Suryo Rahmanto Y, Richardson DR. The translational regulator eIF3a: the tricky eIF3 subunit! Biochim Biophys Acta Rev Cancer 2010; 1806:275-86. [PMID: 20647036 DOI: 10.1016/j.bbcan.2010.07.005] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2010] [Revised: 07/07/2010] [Accepted: 07/11/2010] [Indexed: 01/10/2023]
Abstract
Regulation of gene expression is a fundamental step in cellular physiology as abnormalities in this process may lead to de-regulated growth and cancer. Translation of mRNA is mainly regulated at the rate-limiting initiation step, where many eukaryotic initiation factors (eIFs) are involved. The largest and most complex initiation factor is eIF3 which plays a role in translational regulation, cell growth and cancer. The largest subunit of eIF3 is eIF3a, although it is not required for the general function of eIF3 in translation initiation. However, eIF3a may play a role as a regulator of a subset of mRNAs and has been demonstrated to regulate the expression of p27(kip1), tyrosinated α-tubulin and ribonucleotide reductase M2 subunit. These molecules have a pivotal role in the regulation of the cell cycle. Moreover, the eIF3a mRNA is ubiquitously expressed in all tissues at different levels and is found elevated in a number of cancer types. eIF3a can modulate the cell cycle and may be a translational regulator for proteins important for entrance into S phase. The expression of eIF3a is decreased in differentiated cells in culture and the suppression of eIF3a expression can reverse the malignant phenotype and change the sensitivity of cells to cell cycle modulators. However, the role of eIF3a in cancer is still unclear. In fact, some studies have identified eIF3a to be involved in cancer development, while other results indicate that it could provide protection against evolution into higher malignancy. Together, these findings highlight the "tricky" and interesting nature of eIF3a.
Collapse
Affiliation(s)
- Federica Saletta
- Iron Metabolism and Chelation Program, Department of Pathology and Bosch Institute, Blackburn Building (D06), University of Sydney, Sydney, New South Wales, 2006 Australia
| | | | | |
Collapse
|
28
|
Grzmil M, Rzymski T, Milani M, Harris AL, Capper RG, Saunders NJ, Salhan A, Ragoussis J, Norbury CJ. An oncogenic role of eIF3e/INT6 in human breast cancer. Oncogene 2010; 29:4080-9. [PMID: 20453879 DOI: 10.1038/onc.2010.152] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Altered expression of the eukaryotic translation initiation factor 3 (eIF3) subunit eIF3e/INT6 has been described in various types of human cancer, but the nature of its involvement in tumorigenesis is not yet clear. Using immunohistochemical analysis of 81 primary breast cancers, we found that high tumor grade correlated significantly with elevated cytoplasmic eIF3e level in epithelial tumor cells. Analysis of protein synthesis after siRNA-mediated knockdown in breast cancer cell lines indicated that eIF3e is not required for bulk translation. Microarray analysis of total and polysomal RNAs nonetheless identified distinct sets of mRNAs regulated either positively or negatively by eIF3e; functional classification of these revealed a marked enrichment of genes involved in cell proliferation, invasion and apoptosis. Validated mRNA targets regulated positively at the translational level by eIF3e included urokinase-type plasminogen activator and apoptotic regulator BCL-XL, whereas synthesis of proteins including the mitotic checkpoint component MAD2L1 was negatively regulated. Finally, eIF3e-depleted breast carcinoma cells showed reduced in vitro invasion and proliferation. Taken together, our study data suggest that eIF3e has a positive role in breast cancer progression. It regulates the translation, and in some cases abundance, of mRNAs involved in key aspects of cancer cell biology.
Collapse
Affiliation(s)
- M Grzmil
- Sir William Dunn School of Pathology, University of Oxford, Oxford, UK
| | | | | | | | | | | | | | | | | |
Collapse
|
29
|
Abstract
Remarkable progress has been made in defining a new understanding of the role of mRNA translation and protein synthesis in human cancer. Translational control is a crucial component of cancer development and progression, directing both global control of protein synthesis and selective translation of specific mRNAs that promote tumour cell survival, angiogenesis, transformation, invasion and metastasis. Translational control of cancer is multifaceted, involving alterations in translation factor levels and activities unique to different types of cancers, disease stages and the tumour microenvironment. Several clinical efforts are underway to target specific components of the translation apparatus or unique mRNA translation elements for cancer therapeutics.
Collapse
|
30
|
Chen L, Endler A, Shibasaki F. Hypoxia and angiogenesis: regulation of hypoxia-inducible factors via novel binding factors. Exp Mol Med 2010; 41:849-57. [PMID: 19942820 DOI: 10.3858/emm.2009.41.12.103] [Citation(s) in RCA: 109] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
The mechanisms that regulate angiogenesis in hypoxia or hypoxic microenvironment are modulated by several pro- and antiangiogenic factors. Hypoxia-inducible factors (HIFs) have been established as the basic and major inducers of angiogenesis, but understanding the role of interacting proteins is becoming increasingly important to elucidate the angiogenic processes of a hypoxic response. In particular, with regard to wound healing and the novel therapies for vascular disorders such as ischemic brain and heart attack, it is essential to gain insights in the formation and regulation of HIF transcriptional machineries related to angiogenesis. Further, identification of alternative ways of inhibiting tumor growth by disrupting the growth-triggering mechanisms of increasing vascular supply via angiogenesis depends on the knowledge of how tumor cells develop their own vasculature. Here, we review our findings on the interactions of basic HIFs, HIF-1 alpha and HIF-2 alpha, with their regulatory binding proteins, histone deacetylase 7 (HDAC7) and translation initiation factor 6 (Int6), respectively. The present results and discussion revealed new regulatory interactions of HIF-related mechanisms.
Collapse
Affiliation(s)
- Li Chen
- Translation Research Project, Tokyo Metropolitan Institute of Medical Science, Tokyo 156-8506, Japan
| | | | | |
Collapse
|
31
|
Koh MY, Powis G. HAF : the new player in oxygen-independent HIF-1alpha degradation. Cell Cycle 2009; 8:1359-66. [PMID: 19377289 DOI: 10.4161/cc.8.9.8303] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Adaptation to hypoxia is primarily mediated by the hypoxia-inducible transcription factor, HIF. The regulation of HIF activity by the oxygen-dependent degradation of the HIF-1alpha and HIF-2alpha subunits by the pVHL E3 ligase complex has been well characterized. We have recently described the hypoxia-associated factor, HAF, as an E3 ligase for HIF-1alpha that does not degrade HIF-2alpha. Here we summarize the mechanism of HAF-mediated HIF-1alpha degradation and the importance of oxygen-independent HIF-1alpha regulation in cancer. We also discuss the implications of the new HAF: HIF-1alpha degradation pathway with respect to other novel mediators of oxygen-independent HIF-alpha degradation. Finally, we review the significance of HAF as an isoform-specific E3 ligase in light of new information on the non-overlapping functions of HIF-1alpha and HIF-2alpha in cancer.
Collapse
Affiliation(s)
- Mei Yee Koh
- Department of Experimental Therapeutics, MD Anderson Cancer Center, Houston, TX 77030, USA.
| | | |
Collapse
|
32
|
Ding XC, Slack FJ, Grosshans H. The let-7 microRNA interfaces extensively with the translation machinery to regulate cell differentiation. Cell Cycle 2008; 7:3083-90. [PMID: 18818519 DOI: 10.4161/cc.7.19.6778] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
MicroRNAs (miRNAs) are noncoding RNAs that regulate numerous target genes through a posttranscriptional mechanism and thus control major developmental pathways. The phylogenetically conserved let-7 miRNA regulates cell proliferation and differentiation, thus functioning as a key regulator of developmental timing in C. elegans and a tumor suppressor gene in humans. Using a reverse genetic screen, we have identified genetic interaction partners of C. elegans let-7, including known and novel potential target genes. Initial identification of several translation initiation factors as suppressors of a let-7 mutation led us to systematically examine genetic interaction between let-7 and the translational machinery, which we found to be widespread. In the presence of wild-type let-7, depletion of the translation initiation factor eIF3 resulted in precocious cell differentiation, suggesting that developmental timing is translationally regulated, possibly by let-7. As overexpression of eIF3 in humans promotes translation of mRNAs that are also targets of let-7-mediated repression, we suggest that eIF3 may directly or indirectly oppose let-7 activity. This might provide an explanation for the opposite functions of let-7 and eIF3 in regulating tumorigenesis.
Collapse
Affiliation(s)
- Xavier C Ding
- Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland
| | | | | |
Collapse
|
33
|
Doldan A, Chandramouli A, Shanas R, Bhattacharyya A, Leong SPL, Nelson MA, Shi J. Loss of the eukaryotic initiation factor 3f in melanoma. Mol Carcinog 2008; 47:806-13. [PMID: 18381585 DOI: 10.1002/mc.20436] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Aberrant regulation of the translation initiation is known to contribute to tumorigenesis. eIF3 plays an important role in translation initiation. eIF3f is the p47 subunit of the eIF3 complex whose function in cancer is not clear. Initial studies from our group indicated that eIF3f expression is decreased in melanoma. Overexpression of eIF3f inhibits translation and induces apoptosis in melanoma cells. The eIF3f gene is located at chromosome region 11p15.4. Loss of 11p15.4 is a common event in many tumors including melanoma. In order to investigate the molecular mechanism of the decreased expression of eIF3f in melanoma, we performed loss of heterozygosity (LOH) analysis in 24 melanoma specimens using three microsatellite markers encompassing the eIF3f gene. We showed that the prevalence of LOH ranged from 75% to 92% in melanoma. We also performed eIF3f gene copy number analysis using quantitative real-time PCR to further confirm the specific allelic loss of the eIF3f gene in melanoma. We demonstrated a statistically significant decrease of the eIF3f gene copy number in melanoma compared with normal tissues with a tumor/normal ratio of 0.52. To further elucidate the somatic genetic alterations, we carried out mutation analysis covering the entire coding region and 5'UTR of the eIF3f gene in melanoma tissues and cell lines. Despite some polymorphisms, we did not find any mutations. Furthermore, immunohistochemistry analysis demonstrated that eIF3f protein expression is decreased in melanoma compared to benign nevi. These data provide new insight into the understanding of the molecular pathogenesis of eIF3f during melanoma tumorigenesis.
Collapse
Affiliation(s)
- Adriana Doldan
- Department of Pathology, University of Arizona, Tucson, Arizona 85724, USA
| | | | | | | | | | | | | |
Collapse
|
34
|
Callahan R, Smith GH. Common integration sites for MMTV in viral induced mouse mammary tumors. J Mammary Gland Biol Neoplasia 2008; 13:309-21. [PMID: 18709449 PMCID: PMC3104473 DOI: 10.1007/s10911-008-9092-6] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/26/2008] [Accepted: 07/04/2008] [Indexed: 10/21/2022] Open
Abstract
The paradigm of mammary cancer induction by the mouse mammary tumor virus (MMTV) is used to illustrate the body of evidence that supports the hypothesis that mammary epithelial stem/progenitor cells represent targets for oncogenic transformation. It is argued that this is not a special case applicable only to MMTV-induced mammary cancer, because MMTV acts as an environmental mutagen producing random interruptions in the somatic DNA of infected cells by insertion of proviral DNA copies. In addition to disrupting the host genome, the proviral DNA also influences gene expression through its associated enhancer sequences over significant inter-genomic distances. Genes commonly affected by MMTV insertion in multiple individual tumors include, the Wnt, FGF, RSpo gene families as well as eIF3e and Notch4. All of these gene families are known to play essential roles in stem cell maintenance and behavior in a variety of organs. The MMTV-induced mutations accumulate in cells that are long-lived and possess the properties of stem cells, namely, self-renewal and the capacity to produce divergent epithelial progeny through asymmetric division. The evidence shows that epithelial cells with these properties are present in normal mammary glands, may be infected with MMTV, become transformed to produce epithelial hyperplasia through MMTV-induced mutagenesis and progress to frank mammary malignancy. Retroviral marking via MMTV proviral insertion demonstrates that this process progresses from a single mammary epithelial cell that possesses all of the features ascribed to tissue-specific stem cells.
Collapse
Affiliation(s)
- Robert Callahan
- Mammary Gland Biology and Tumorigenesis Laboratory, National Cancer Institute, Building 37/Room 1118A, MSC4254, Bethesda, MD 20892, USA
| | - Gilbert H. Smith
- National Cancer Institute, Building 37/Room 1112A, MSC 4254, Bethesda, MD 20892, USA
| |
Collapse
|
35
|
Lei YX, Wei L, Wang M, Wu GR, Li M. Malignant transformation and abnormal expression of eukaryotic initiation factor in bronchial epithelial cells induced by cadmium chloride. BIOMEDICAL AND ENVIRONMENTAL SCIENCES : BES 2008; 21:332-338. [PMID: 18837298 DOI: 10.1016/s0895-3988(08)60051-3] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
OBJECTIVE To analyze the relationship between malignant transformation and abnormal expression of eukaryotic initiation factor 3 (eIF3 p36) in human bronchial epithelial (16HBE) cells induced by cadmium chloride (CdCl2). METHODS 16HBE cells were treated several times with different concentrations of CdCl2. Tumorigenic potential of transformed cells was identified by assays for anchorage-independent growth in soft agar and for tumorigenicity in nude mice after the 35th passage. Total RNA was isolated from 16HBE cells induced by CdCl2, including non-transformed, Cd-transformed, and Cd-tumorigenic cell lines. Special primers for eIF3 p36 were designed and the expression of eIF3 mRNA in different cell lines was detected with fluorescent quantitative-polymerase chain reaction technique (FQ-PCR). RESULTS The 35th passage of 16HBE cells transformed by CdCl2 exhibited overlapping growth. Compared with the non-transformed cells, colonies of transformed cell lines in soft agar showed statistically significant increases and dose-dependent effects (P<0.01). All Cd-induced transformed cell lines formed tumors in nude mice within 2 weeks of inoculation, but none of the mice injected with non-transformed cells showed tumors even after 3 weeks. All tumors were pathologically identified as poorly differentiated squamous cell carcinoma. The eIF3 p36 genes in different stages of 16HBE cells transformed by CdCl2 were elevated as compared with the non-transformed control (P<0.01), and the eIF3 expression increased with the degree of cell malignancy. CONCLUSION CdCl2 is capable of inducing morphological transformation in 16HBE cells and transformed cells are potentially tumorigenic. Over-expression of eIF3 p36 is positively correlated with malignant transformation of 16HBE cells induced by CdCl2 and may be one of the molecular mechanisms potentially responsible for carcinogenesis due to Cd.
Collapse
Affiliation(s)
- Yi-Xiong Lei
- Department of Preventive Medicine, Guangzhou Medical College, Guangzhou 510182, Guangdong, China.
| | | | | | | | | |
Collapse
|
36
|
Rencus-Lazar S, Amir Y, Wu J, Chien CT, Chamovitz DA, Segal D. The proto-oncogene Int6 is essential for neddylation of Cul1 and Cul3 in Drosophila. PLoS One 2008; 3:e2239. [PMID: 18493598 PMCID: PMC2375110 DOI: 10.1371/journal.pone.0002239] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2007] [Accepted: 04/04/2008] [Indexed: 11/24/2022] Open
Abstract
Int6 is a proto-oncogene implicated in various types of cancer, but the mechanisms underlying its activity are not clear. Int6 encodes a subunit of the eukaryotic translation initiation factor 3, and interacts with two related complexes, the proteasome, whose activity is regulated by Int6 in S. pombe, and the COP9 signalosome. The COP9 signalosome regulates the activity of Cullin-Ring Ubiquitin Ligases via deneddylation of their cullin subunit. We report here the generation and analysis of two Drosophila mutants in Int6. The mutants are lethal demonstrating that Int6 is an essential gene. The mutant larvae accumulate high levels of non-neddylated Cul1, suggesting that Int6 is a positive regulator of cullin neddylation. Overexpression in Int6 in cell culture leads to accumulation of neddylated cullins, further supporting a positive role for Int6 in regulating neddylation. Thus Int6 and the COP9 signalosome play opposing roles in regulation of cullin neddylation.
Collapse
Affiliation(s)
- Sigal Rencus-Lazar
- Department of Molecular Microbiology, Tel Aviv University, Tel Aviv, Israel
- Department of Biotechnology, Tel Aviv University, Tel Aviv, Israel
| | - Yaniv Amir
- Department of Molecular Microbiology, Tel Aviv University, Tel Aviv, Israel
- Department of Biotechnology, Tel Aviv University, Tel Aviv, Israel
| | - Junetai Wu
- Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan
| | | | - Daniel A. Chamovitz
- Department of Plant Sciences, Tel Aviv University, Tel Aviv, Israel
- * E-mail: (DC); (DS)
| | - Daniel Segal
- Department of Molecular Microbiology, Tel Aviv University, Tel Aviv, Israel
- Department of Biotechnology, Tel Aviv University, Tel Aviv, Israel
- * E-mail: (DC); (DS)
| |
Collapse
|
37
|
Marshall L, Kenneth NS, White RJ. Elevated tRNA(iMet) synthesis can drive cell proliferation and oncogenic transformation. Cell 2008; 133:78-89. [PMID: 18394991 DOI: 10.1016/j.cell.2008.02.035] [Citation(s) in RCA: 108] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2007] [Revised: 12/14/2007] [Accepted: 02/06/2008] [Indexed: 12/23/2022]
Abstract
Characteristics of transformed and tumor cells include increased levels of protein synthesis and elevated expression of RNA polymerase (pol) III products, such as tRNAs and 5S rRNA. However, whether deregulated pol III transcription contributes to transformation has been unclear. Generating cell lines expressing an inducible pol III-specific transcription factor, Brf1, allowed us to raise tRNA and 5S rRNA levels specifically. Brf1 induction caused an increase in cell proliferation and oncogenic transformation, whereas depletion of Brf1 impeded transformation. Among the gene products induced by Brf1 is the tRNA(iMet) that initiates polypeptide synthesis. Overexpression of tRNA(iMet) is sufficient to stimulate cell proliferation and allow immortalized fibroblasts to form foci in culture and tumors in mice. The data indicate that elevated tRNA synthesis can promote cellular transformation.
Collapse
Affiliation(s)
- Lynne Marshall
- Institute of Biomedical and Life Sciences, University of Glasgow, Glasgow G12 8QQ, UK
| | | | | |
Collapse
|
38
|
Doldan A, Chandramouli A, Shanas R, Bhattacharyya A, Cunningham JT, Nelson MA, Shi J. Loss of the eukaryotic initiation factor 3f in pancreatic cancer. Mol Carcinog 2008; 47:235-44. [PMID: 17918192 DOI: 10.1002/mc.20379] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Aberrant regulation of the translation initiation is known to contribute to tumorigenesis. eIF3 plays an important role in translation initiation. eIF3f is the p47 subunit of the eIF3 complex whose function in cancer is not clear. Initial studies from our group indicated that eIF3f expression is decreased in pancreatic cancer. Overexpression of eIF3f induces apoptosis in pancreatic cancer cells. The eIF3f gene is located at chromosome band region 11p15.4. Loss of 11p15.4 is a common event in many tumors including pancreatic cancer. In order to investigate the molecular mechanism of the decreased expression of eIF3f in pancreatic cancer, we performed loss of heterozygosity (LOH) analysis in 32 pancreatic cancer specimens using three microsatellite markers encompassing the eIF3f gene. We showed that the prevalence of LOH ranged from 71% to 93%. We also performed eIF3f gene copy number analysis using quantitative real time PCR to further confirm the specific allelic loss of eIF3f gene in pancreatic cancer. We demonstrated a statistically significant decrease of eIF3f gene copy number in pancreatic tumors compared with normal tissues with a tumor/normal ratio of 0.24. Furthermore, RNA in situ hybridization and tissue microarray immunohistochemistry analysis demonstrated that eIF3f expression is significantly decreased in human pancreatic adenocarcinoma tissues compared to normal pancreatic tissues. These data provides new insight into the understanding of the molecular pathogenesis of eIF3f during pancreatic tumorigenesis.
Collapse
Affiliation(s)
- Adriana Doldan
- Department of Pathology, University of Arizona, Tucson, Arizona 85724, USA
| | | | | | | | | | | | | |
Collapse
|
39
|
Mack DL, Boulanger CA, Callahan R, Smith GH. Expression of truncated Int6/eIF3e in mammary alveolar epithelium leads to persistent hyperplasia and tumorigenesis. Breast Cancer Res 2008; 9:R42. [PMID: 17626637 PMCID: PMC2206715 DOI: 10.1186/bcr1742] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2006] [Revised: 03/22/2007] [Accepted: 07/12/2007] [Indexed: 11/30/2022] Open
Abstract
Introduction Int6 has been shown to be an interactive participant with the protein translation initiation complex eIF3, the COP9 signalosome and the regulatory lid of the 26S proteasome. Insertion of mouse mammary tumor virus into the Int6 locus creates a C-terminally truncated form of the protein. Expression of the truncated form of Int6 (Int6sh) in stably transfected human and mouse mammary epithelial cell lines leads to cellular transformation. In addition, decreased expression of Int6/eIF3e is observed in approximately one third of all human breast carcinomas. Methods To validate that Int6sh has transforming activity in vivo, a transgenic mouse model was designed using the whey acidic protein (Wap) promoter to target expression of truncated Int6 to differentiating alveolar epithelial cells in the mammary gland. Microarray analyses were performed on normal, premalignant and malignant WapInt6sh expressing tissues. Results Mammary tumors developed in 42% of WapInt6sh heterozygous parous females at an average age of 18 months. In WapInt6sh mice, the contralateral mammary glands from both tumorous and non-tumorous tissues contained widespread focal alveolar hyperplasia. Only 4% of WapInt6sh non-breeding females developed tumors by 2 years of age. The Wap promoter is active only during estrus in the mammary tissue of cycling non-pregnant mice. Microarray analyses of mammary tissues demonstrated that Int6sh expression in the alveolar tissue altered the mammary transcriptome in a specific manner that was detectable even in the first pregnancy. This Int6sh-specific transcriptome pattern subsequently persisted in both the Int6sh-expressing alveolar hyperplasia and mammary tumors. These observations are consistent with the conclusion that WapInt6sh-expressing alveolar cells survive involution following the cessation of lactation, and subsequently give rise to the mammary tumors that arise in aging multiparous females. Conclusion These observations provide direct in vivo evidence that mammary-specific expression of the Int6sh truncation leads to persistence of alveolar hyperplasia with the accompanying increased predisposition to mammary tumorigenesis.
Collapse
MESH Headings
- Animals
- Biomarkers, Tumor/metabolism
- Cell Transformation, Neoplastic
- Epithelium/metabolism
- Eukaryotic Initiation Factor-3/genetics
- Eukaryotic Initiation Factor-3/metabolism
- Female
- Gene Expression Profiling
- Humans
- Hyperplasia/etiology
- Hyperplasia/pathology
- Male
- Mammary Glands, Animal/metabolism
- Mammary Glands, Animal/pathology
- Mammary Neoplasms, Experimental/etiology
- Mammary Neoplasms, Experimental/pathology
- Mice
- Mice, Transgenic
- Milk Proteins/genetics
- Oligonucleotide Array Sequence Analysis
- Plasmids/genetics
- Pregnancy
- Promoter Regions, Genetic
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- Reverse Transcriptase Polymerase Chain Reaction
- Sequence Deletion
- Transfection
- Tumor Cells, Cultured
Collapse
Affiliation(s)
- David L Mack
- Mammary Biology and Tumorigenesis Laboratory, National Cancer Institute, National Institutes of Health; Bethesda, Maryland, 20892, USA
| | - Corinne A Boulanger
- Mammary Biology and Tumorigenesis Laboratory, National Cancer Institute, National Institutes of Health; Bethesda, Maryland, 20892, USA
| | - Robert Callahan
- Mammary Biology and Tumorigenesis Laboratory, National Cancer Institute, National Institutes of Health; Bethesda, Maryland, 20892, USA
| | - Gilbert H Smith
- Mammary Biology and Tumorigenesis Laboratory, National Cancer Institute, National Institutes of Health; Bethesda, Maryland, 20892, USA
| |
Collapse
|
40
|
Yahalom A, Kim TH, Roy B, Singer R, von Arnim AG, Chamovitz DA. Arabidopsis eIF3e is regulated by the COP9 signalosome and has an impact on development and protein translation. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2008; 53:300-11. [PMID: 18067529 DOI: 10.1111/j.1365-313x.2007.03347.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
The roles of individual eukaryotic translation initiation factor 3 (eIF3) subunits are largely unclear, although some are essential, while others are thought to have regulatory roles. The 'e' subunit, also known as Int-6/Int6, is a candidate for a regulatory subunit as it is not essential for translation initiation in yeasts. eIF3e associates with the COP9 signalosome, and localizes to the nucleus in certain tissues. To further elucidate the roles of eIF3e, we have taken a genetic approach using Arabidopsis as a model system. Overexpression of eIF3e results in defects similar to mutations in the COP9 signalosome. eIF3e protein, but not transcript, over accumulates in csn mutants, and eIF3e is degraded in a proteasome-dependent fashion. In vitro and in vivo assays suggest that excess eIF3e inhibits translation. We conclude that the COP9 signalosome maintains a precise regulation of eIF3e levels, which is necessary for normal development in Arabidopsis.
Collapse
Affiliation(s)
- Avital Yahalom
- Department of Plant Sciences, Tel Aviv University, Tel Aviv 69978, Israel
| | | | | | | | | | | |
Collapse
|
41
|
Green EM, Barrett CF, Bultynck G, Shamah SM, Dolmetsch RE. The tumor suppressor eIF3e mediates calcium-dependent internalization of the L-type calcium channel CaV1.2. Neuron 2007; 55:615-32. [PMID: 17698014 PMCID: PMC2384234 DOI: 10.1016/j.neuron.2007.07.024] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2006] [Revised: 04/11/2007] [Accepted: 07/16/2007] [Indexed: 12/20/2022]
Abstract
Voltage-gated calcium channels (VGCCs) convert electrical activity into calcium (Ca2+) signals that regulate cellular excitability, differentiation, and connectivity. The magnitude and kinetics of Ca2+ signals depend on the number of VGCCs at the plasma membrane, but little is known about the regulation of VGCC surface expression. We report that electrical activity causes internalization of the L-type Ca2+ channel (LTC) CaV1.2 and that this is mediated by binding to the tumor suppressor eIF3e/Int6 (eukaryotic initiation factor 3 subunit e). Using total internal reflection microscopy, we identify a population of CaV1.2 containing endosomes whose rapid trafficking is strongly regulated by Ca2+. We define a domain in the II-III loop of CaV1.2 that binds eIF3e and is essential for the activity dependence of both channel internalization and endosomal trafficking. These findings provide a mechanism for activity-dependent internalization and trafficking of CaV1.2 and provide a tantalizing link between Ca2+ homeostasis and a mammalian oncogene.
Collapse
Affiliation(s)
- Eric M. Green
- Department of Neurobiology, Stanford University, 299 Campus Drive, Fairchild Research Building D227, Stanford, CA 94305, USA
| | - Curtis F. Barrett
- Department of Molecular and Cellular Physiology, Stanford University, 299 Campus Drive, Fairchild Research Building D227, Stanford, CA 94305, USA
| | - Geert Bultynck
- Department of Biological Sciences, Stanford University, 299 Campus Drive, Fairchild Research Building D227, Stanford, CA 94305, USA
| | - Steven M. Shamah
- Archemix Corporation, 300 Third Street, Cambridge, MA 02142, USA
| | - Ricardo E. Dolmetsch
- Department of Neurobiology, Stanford University, 299 Campus Drive, Fairchild Research Building D227, Stanford, CA 94305, USA
- *Correspondence:
| |
Collapse
|
42
|
Scoles DR. The merlin interacting proteins reveal multiple targets for NF2 therapy. Biochim Biophys Acta Rev Cancer 2007; 1785:32-54. [PMID: 17980164 DOI: 10.1016/j.bbcan.2007.10.001] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2007] [Revised: 09/29/2007] [Accepted: 10/03/2007] [Indexed: 01/20/2023]
Abstract
The neurofibromatosis 2 (NF2) tumor suppressor protein merlin is commonly mutated in human benign brain tumors. The gene altered in NF2 was located on human chromosome 22q12 in 1993 and the encoded protein named merlin and schwannomin. Merlin has homology to ERM family proteins, ezrin, radixin, and moesin, within the protein 4.1 superfamily. In efforts to determine merlin function several groups have discovered 34 merlin interacting proteins, including ezrin, radixin, moesin, CD44, layilin, paxillin, actin, N-WASP, betaII-spectrin, microtubules, TRBP, eIF3c, PIKE, NHERF, MAP, RalGDS, RhoGDI, EG1/magicin, HEI10, HRS, syntenin, caspr/paranodin, DCC, NGB, CRM1/exportin, SCHIP1, MYPT-1-PP1delta, RIbeta, PKA, PAK (three types), calpain and Drosophila expanded. Many of the proteins that interact with the merlin N-terminal domain also bind ezrin, while other merlin interacting proteins do not bind other members of the ERM family. Merlin also interacts with itself. This review describes these proteins, their possible roles in NF2, and the resultant hypothesized merlin functions. Review of all of the merlin interacting proteins and functional consequences of losses of these interactions reveals multiple merlin actions in PI3-kinase, MAP kinase and small GTPase signaling pathways that might be targeted to inhibit the proliferation of NF2 tumors.
Collapse
Affiliation(s)
- Daniel R Scoles
- Women's Cancer Research Institute, CSMC Burns and Allen Research Institute, Cedars-Sinai Medical Center, 8700 Beverly Boulevard, Los Angeles, CA 90048, USA.
| |
Collapse
|
43
|
Grzmil M, Whiting D, Maule J, Anastasaki C, Amatruda JF, Kelsh RN, Norbury CJ, Patton EE. The INT6 cancer gene and MEK signaling pathways converge during zebrafish development. PLoS One 2007; 2:e959. [PMID: 17895999 PMCID: PMC1978538 DOI: 10.1371/journal.pone.0000959] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2007] [Accepted: 09/02/2007] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Int-6 (integration site 6) was identified as an oncogene in a screen of tumorigenic mouse mammary tumor virus (MMTV) insertions. INT6 expression is altered in human cancers, but the precise role of disrupted INT6 in tumorigenesis remains unclear, and an animal model to study Int-6 physiological function has been lacking. PRINCIPAL FINDINGS Here, we create an in vivo model of Int6 function in zebrafish, and through genetic and chemical-genetic approaches implicate Int6 as a tissue-specific modulator of MEK-ERK signaling. We find that Int6 is required for normal expression of MEK1 protein in human cells, and for Erk signaling in zebrafish embryos. Loss of either Int6 or Mek signaling causes defects in craniofacial development, and Int6 and Erk-signaling have overlapping domains of tissue expression. SIGNIFICANCE Our results provide new insight into the physiological role of vertebrate Int6, and have implications for the treatment of human tumors displaying altered INT6 expression.
Collapse
Affiliation(s)
- Michal Grzmil
- Sir William Dunn School of Pathology, University of Oxford, Oxford, United Kingdom
| | - Danny Whiting
- Sir William Dunn School of Pathology, University of Oxford, Oxford, United Kingdom
| | - John Maule
- MRC Human Genetics Unit and University of Edinburgh Cancer Research Centre, Western General Hospital, Edinburgh, United Kingdom
| | - Corina Anastasaki
- MRC Human Genetics Unit and University of Edinburgh Cancer Research Centre, Western General Hospital, Edinburgh, United Kingdom
| | - James F. Amatruda
- Departments of Pediatrics, Internal Medicine and Molecular Biology, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
| | - Robert N. Kelsh
- Centre for Regenerative Medicine, Developmental Biology Programme, Department of Biology and Biochemistry, University of Bath, Bath, United Kingdom
| | - Chris J. Norbury
- Sir William Dunn School of Pathology, University of Oxford, Oxford, United Kingdom
| | - E. Elizabeth Patton
- Sir William Dunn School of Pathology, University of Oxford, Oxford, United Kingdom
- MRC Human Genetics Unit and University of Edinburgh Cancer Research Centre, Western General Hospital, Edinburgh, United Kingdom
- * To whom correspondence should be addressed. E-mail:
| |
Collapse
|
44
|
Chen L, Uchida K, Endler A, Shibasaki F. Mammalian Tumor Suppressor Int6 Specifically Targets Hypoxia Inducible Factor 2α for Degradation by Hypoxia- and pVHL-independent Regulation. J Biol Chem 2007; 282:12707-16. [PMID: 17324924 DOI: 10.1074/jbc.m700423200] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The hypoxia-inducible factors HIF-1 alpha and HIF-2 alpha are structurally similar as regards their DNA-binding and dimerization domains, but differ in their transactivation domains and, as is shown by experiments using hif-1 alpha(-/-) and hif-2 alpha(-/-) mice, in their functions. This implies that HIF-1 alpha and HIF-2 alpha may have unique target genes. To address this discrepancy and identify HIF-2 alpha-specific target genes, we performed yeast two-hybrid analysis and identified the tumor suppressor Int6/eIF3e/p48 as a novel target gene product involved in HIF-2 alpha regulation. The int6 gene was first identified from a screen in which the mouse mammary tumor virus was employed as an insertional mutagen to identify genes whose functions are critical for breast tumor formation. Here, by using two-hybrid analysis, immunoprecipitation in mammalian cells, and HRE-reporter assays, we report the specific interaction of HIF-2 alpha (but not HIF-1 alpha or HIF-3 alpha) with Int6. The results indicate that the direct interaction of Int6 induces proteasome inhibitor-sensitive HIF-2 alpha degradation. This degradation was clearly observed in renal cell carcinoma 786-O cells, and was found to be both hypoxia- and pVHL-independent. Furthermore, Int6 protein knockdown by int6-siRNA vectors or the dominant-negative mutant Int6-Delta C increased endogenous HIF-2 alpha expression, even under normoxia, and induced sets of critical angiogenic factors comprising vascular endoplasmic growth factor, angiopoietin, and basic fibroblast growth factor mRNA. These results indicate that Int6 is a novel and critical determinant of HIF-2 alpha-dependent angiogenesis as well as cancer formation, and that int6-siRNA transfer may be an effective therapeutic strategy in pathological conditions such as heart and brain ischemia, hepatic cirrhosis, and obstructive vessel diseases.
Collapse
Affiliation(s)
- Li Chen
- Translation Research Project, Tokyo Metropolitan Institute of Medical Science, 3-18-22 Honkomagome, Bunkyo-ku, Tokyo 113-8613, Japan
| | | | | | | |
Collapse
|
45
|
Traicoff JL, Chung JY, Braunschweig T, Mazo I, Shu Y, Ramesh A, D'Amico MW, Galperin MM, Knezevic V, Hewitt SM. Expression of EIF3-p48/INT6, TID1 and Patched in cancer, a profiling of multiple tumor types and correlation of expression. J Biomed Sci 2007; 14:395-405. [PMID: 17385060 DOI: 10.1007/s11373-007-9149-3] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2006] [Accepted: 12/21/2006] [Indexed: 10/23/2022] Open
Abstract
Alterations in eIF3-p48/INT6 gene expression have been implicated in murine and human mammary carcinogenesis. We examined levels of INT6 protein in human tumors and determined that breast and colon tumors clustered into distinct groups based on levels of INT6 expression and clinicopathological variables. We performed multiplex tissue immunoblotting of breast, colon, lung, and ovarian tumor tissues and found that INT6 protein levels positively correlated with those of TID1, Patched, p53, c-Jun, and phosphorylated-c-Jun proteins in a tissue-specific manner. INT6 and TID1 showed significant positive correlation in all tissue types tested. These findings were confirmed by immunohistochemical staining of INT6 and TID1. Further evidence supporting a cooperative role for INT6 and TID1 is the presence of endogenous INT6 and TID1 proteins as complexes. We detected co-immunoprecipitation between INT6 and TID1, as well as between INT6 and Patched. These findings suggest potential integrated roles for INT6, TID1, and Patched proteins in cell growth, development, and tumorigenesis. Additionally, these data suggest that the combination of INT6, TID1, and Patched protein levels may be useful biomarkers for the development of diagnostic assays.
Collapse
|
46
|
Buchsbaum S, Morris C, Bochard V, Jalinot P. Human INT6 interacts with MCM7 and regulates its stability during S phase of the cell cycle. Oncogene 2007; 26:5132-44. [PMID: 17310990 DOI: 10.1038/sj.onc.1210314] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The mouse int6 gene is a frequent integration site of the mouse mammary tumor virus and INT6 silencing by RNA interference in HeLa cells causes an increased number of cells in the G2/M phases of the cell cycle, along with mitotic defects. In this report, we investigated the functional significance of the interaction between INT6 and MCM7, which was observed in a two-hybrid screen performed with INT6 as bait. It was found that proteasome inhibition strengthens interaction between both proteins and that INT6 stabilizes MCM7. Removal of MCM7 from chromatin as replication proceeds was accelerated in INT6-silenced cells and reduced amounts of protein were transiently observed, followed by a correction resulting from stimulation of mcm7 gene expression. Synchronized cells depleted for either INT6 or MCM7 display a reduction in thymidine incorporation and a reinforced association of RPA and claspin with chromatin. These data show that INT6 stabilizes chromatin-bound MCM7 and that alteration of this effect is associated with replication deficiency.
Collapse
Affiliation(s)
- S Buchsbaum
- Laboratoire de Biologie Moléculaire de la Cellule, UMR5161 CNRS/ENS de Lyon, IFR 128 Biosciences Lyon Gerland, Lyon cedex 07, Rhone, France
| | | | | | | |
Collapse
|
47
|
Russo J, Balogh GA, Heulings R, Mailo DA, Moral R, Russo PA, Sheriff F, Vanegas J, Russo IH. Molecular basis of pregnancy-induced breast cancer protection. Eur J Cancer Prev 2007; 15:306-42. [PMID: 16835503 DOI: 10.1097/00008469-200608000-00006] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
We have postulated that the lifetime protective effect of an early pregnancy against breast cancer is due to the complete differentiation of the mammary gland characterized by a specific genomic signature imprinted by the physiological process of pregnancy. In the present work, we show evidence that the breast tissue of postmenopausal parous women has had a shifting of stem cell 1 to stem cell 2 with a genomic signature different from similar structures derived from postmenopausal nulliparous women that have stem cell 1. Those genes that are significantly different are grouped in major categories on the basis of their putative functional significance. Among them are those gene transcripts related to immune surveillance, DNA repair, transcription, chromatin structure/activators/co-activators, growth factor and signal transduction pathway, transport and cell trafficking, cell proliferation, differentiation, cell adhesion, protein synthesis and cell metabolism. From these data, it was concluded that during pregnancy there are significant genomic changes that reflect profound alterations in the basic physiology of the mammary gland that explain the protective effect against carcinogenesis. The implication of this knowledge is that when the genomic signature of protection or refractoriness to carcinogenesis is acquired by the shifting of stem cell 1 to stem cell 2, the hormonal milieu induced by pregnancy or pregnancy-like conditions is no longer required. This is a novel concept that challenges the current knowledge that a chemopreventive agent needs to be given for a long period to suppress a metabolic pathway or abrogate the function of an organ.
Collapse
Affiliation(s)
- Jose Russo
- Breast Cancer Research Laboratory, Fox Chase Cancer Center, Philadelphia, Pennsylvania 19111, USA.
| | | | | | | | | | | | | | | | | |
Collapse
|
48
|
Dong Z, Zhang JT. Initiation factor eIF3 and regulation of mRNA translation, cell growth, and cancer. Crit Rev Oncol Hematol 2006; 59:169-80. [PMID: 16829125 DOI: 10.1016/j.critrevonc.2006.03.005] [Citation(s) in RCA: 115] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2005] [Revised: 03/30/2006] [Accepted: 03/30/2006] [Indexed: 11/20/2022] Open
Abstract
One important regulation of gene expression in eukaryotes occurs at the level of mRNA translation, specifically at the step of translational initiation. Deregulation at this step will cause abnormal gene expression, leading to altered cell growth and possibly cancer. Translational initiation is controlled by multiple eIFs and one of these, eIF3, is the most complex and important factor for regulation of translation. Various subunits of eIF3 have recently been implicated to play important roles in regulating translation of specific mRNAs encoding proteins important for cell growth control. The expression of these eIF3 subunits has also been found altered in various human tumors and their altered expression may cause cancer and/or affect prognosis. Although the importance of translational regulation in cell growth control and oncogenesis is being slowly recognized, more vigorous studies on the role of eIFs in oncogenesis and cancer will likely benefit diagnosis, prognosis, and treatment of human cancers.
Collapse
Affiliation(s)
- Zizheng Dong
- Department of Pharmacology and Toxicology, Indiana University Cancer Center, Indianapolis, IN 46202, USA
| | | |
Collapse
|
49
|
LeFebvre AK, Korneeva NL, Trutschl M, Cvek U, Duzan RD, Bradley CA, Hershey JWB, Rhoads RE. Translation initiation factor eIF4G-1 binds to eIF3 through the eIF3e subunit. J Biol Chem 2006; 281:22917-32. [PMID: 16766523 PMCID: PMC1880881 DOI: 10.1074/jbc.m605418200] [Citation(s) in RCA: 134] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
eIF3 in mammals is the largest translation initiation factor ( approximately 800 kDa) and is composed of 13 nonidentical subunits designated eIF3a-m. The role of mammalian eIF3 in assembly of the 48 S complex occurs through high affinity binding to eIF4G. Interactions of eIF4G with eIF4E, eIF4A, eIF3, poly(A)-binding protein, and Mnk1/2 have been mapped to discrete domains on eIF4G, and conversely, the eIF4G-binding sites on all but one of these ligands have been determined. The only eIF4G ligand for which this has not been determined is eIF3. In this study, we have sought to identify the mammalian eIF3 subunit(s) that directly interact(s) with eIF4G. Established procedures for detecting protein-protein interactions gave ambiguous results. However, binding of partially proteolyzed HeLa eIF3 to the eIF3-binding domain of human eIF4G-1, followed by high throughput analysis of mass spectrometric data with a novel peptide matching algorithm, identified a single subunit, eIF3e (p48/Int-6). In addition, recombinant FLAG-eIF3e specifically competed with HeLa eIF3 for binding to eIF4G in vitro. Adding FLAG-eIF3e to a cell-free translation system (i) inhibited protein synthesis, (ii) caused a shift of mRNA from heavy to light polysomes, (iii) inhibited cap-dependent translation more severely than translation dependent on the HCV or CSFV internal ribosome entry sites, which do not require eIF4G, and (iv) caused a dramatic loss of eIF4G and eIF2alpha from complexes sedimenting at approximately 40 S. These data suggest a specific, direct, and functional interaction of eIF3e with eIF4G during the process of cap-dependent translation initiation, although they do not rule out participation of other eIF3 subunits.
Collapse
Affiliation(s)
- Aaron K. LeFebvre
- Department of Biochemistry and Molecular Biology and Louisiana State University Health Sciences Center, Shreveport, Louisiana 71130
| | - Nadejda L. Korneeva
- Department of Biochemistry and Molecular Biology and Louisiana State University Health Sciences Center, Shreveport, Louisiana 71130
| | - Marjan Trutschl
- Department of Computer Science, Louisiana State University, Shreveport, Louisiana 71115
| | - Urska Cvek
- Department of Computer Science, Louisiana State University, Shreveport, Louisiana 71115
| | - Roy D. Duzan
- Research Core Facility, Louisiana State University Health Sciences Center, Shreveport, Louisiana 71130
| | - Christopher A. Bradley
- Department of Biochemistry and Molecular Medicine, University of California, Davis, California 95616
| | - John W. B. Hershey
- Department of Biochemistry and Molecular Medicine, University of California, Davis, California 95616
| | - Robert E. Rhoads
- Department of Biochemistry and Molecular Biology and Louisiana State University Health Sciences Center, Shreveport, Louisiana 71130
- To whom correspondence should be addressed: Dept. of Biochemistry and Molecular Biology, Louisiana State University Health Sciences Center, 1501 Kings Hwy., Shreveport, LA 71130-3932. Tel.: 318-675-5161; Fax: 318-675-5180; E-mail:
| |
Collapse
|
50
|
Jenkins CCL, Mata J, Crane RF, Thomas B, Akoulitchev A, Bähler J, Norbury CJ. Activation of AP-1-dependent transcription by a truncated translation initiation factor. EUKARYOTIC CELL 2006; 4:1840-50. [PMID: 16278451 PMCID: PMC1287857 DOI: 10.1128/ec.4.11.1840-1850.2005] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Int6/eIF3e is a highly conserved subunit of eukaryotic translation initiation factor 3 (eIF3) that has also been reported to interact with subunits of the proteasome and the COP9 signalosome. Overexpression of full-length Int6 or a 13-kDa C-terminal fragment, Int6CT, in the fission yeast Schizosaccharomyces pombe causes multidrug resistance that requires the otherwise inessential AP-1 transcription factor Pap1. Here we show for the first time that Int6CT acts to increase the transcriptional activity of Pap1. Microarray hybridization data indicate that Int6CT overexpression resulted in the up-regulation of 67 genes; this expression profile closely matched that of cells overexpressing Pap1. Analysis of the upstream regulatory sequences of these genes showed that the majority contained AP-1 consensus binding sites. Partial defects in ubiquitin-dependent proteolysis have been suggested to confer Pap1-dependent multidrug resistance, but no such defect was seen on Int6CT overexpression. Indeed, none of the previously identified interactions of endogenous Int6 was required for the activation of Pap1 transcription described here. Moreover, Int6CT-induced activation of Pap1-responsive gene expression was independent of the ability of Pap1 to undergo a redox-regulated conformational change which mediates its relocalization to the nucleus and expression of oxidative stress response genes. Int6CT therefore activates Pap1-dependent transcription by a novel mechanism.
Collapse
Affiliation(s)
- Caroline C L Jenkins
- Sir William Dunn School of Pathology, University of Oxford, Oxford OX1 3RE, United Kingdom
| | | | | | | | | | | | | |
Collapse
|