101
|
Mtango NR, Potireddy S, Latham KE. Oocyte quality and maternal control of development. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2008; 268:223-90. [PMID: 18703408 DOI: 10.1016/s1937-6448(08)00807-1] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The oocyte is a unique and highly specialized cell responsible for creating, activating, and controlling the embryonic genome, as well as supporting basic processes such as cellular homeostasis, metabolism, and cell cycle progression in the early embryo. During oogenesis, the oocyte accumulates a myriad of factors to execute these processes. Oogenesis is critically dependent upon correct oocyte-follicle cell interactions. Disruptions in oogenesis through environmental factors and changes in maternal health and physiology can compromise oocyte quality, leading to arrested development, reduced fertility, and epigenetic defects that affect long-term health of the offspring. Our expanding understanding of the molecular determinants of oocyte quality and how these determinants can be disrupted has revealed exciting new insights into the role of oocyte functions in development and evolution.
Collapse
Affiliation(s)
- Namdori R Mtango
- Fels Institute for Cancer Research and Molecular Biology, Temple University School of Medicine, Philadelphia, PA 19140, USA
| | | | | |
Collapse
|
102
|
|
103
|
Ageberg M, Drott K, Olofsson T, Gullberg U, Lindmark A. Identification of a novel and myeloid specific role of the leukemia-associated fusion protein DEK-NUP214 leading to increased protein synthesis. Genes Chromosomes Cancer 2008; 47:276-87. [PMID: 18181180 DOI: 10.1002/gcc.20531] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
MESH Headings
- Apoptosis
- Blotting, Western
- Eukaryotic Initiation Factor-4E/metabolism
- Flow Cytometry
- Gene Expression Regulation, Leukemic/physiology
- Genes, Reporter
- Genetic Vectors
- Humans
- Leukemia, Myeloid, Acute/genetics
- Leukemia, Myeloid, Acute/metabolism
- Luciferases/metabolism
- Neoplasm Proteins/biosynthesis
- Oncogene Proteins, Fusion/physiology
- Phosphorylation
- Protein Biosynthesis
- Reverse Transcriptase Polymerase Chain Reaction
- Sequence Deletion
- Transcription, Genetic
- Transfection
- Tumor Cells, Cultured
Collapse
Affiliation(s)
- Malin Ageberg
- Division of Hematology and Transfusion Medicine, Faculty of Medicine, Lund University, Lund, Sweden.
| | | | | | | | | |
Collapse
|
104
|
Toral-Barza L, Zhang WG, Huang X, McDonald LA, Salaski EJ, Barbieri LR, Ding WD, Krishnamurthy G, Hu YB, Lucas J, Bernan VS, Cai P, Levin JI, Mansour TS, Gibbons JJ, Abraham RT, Yu K. Discovery of lactoquinomycin and related pyranonaphthoquinones as potent and allosteric inhibitors of AKT/PKB: mechanistic involvement of AKT catalytic activation loop cysteines. Mol Cancer Ther 2007; 6:3028-38. [PMID: 17989320 DOI: 10.1158/1535-7163.mct-07-0211] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The serine/threonine kinase AKT/PKB plays a critical role in cancer and represents a rational target for therapy. Although efforts in targeting AKT pathway have accelerated in recent years, relatively few small molecule inhibitors of AKT have been reported. The development of selective AKT inhibitors is further challenged by the extensive conservation of the ATP-binding sites of the AGC kinase family. In this report, we have conducted a high-throughput screen for inhibitors of activated AKT1. We have identified lactoquinomycin as a potent inhibitor of AKT kinases (AKT1 IC(50), 0.149 +/- 0.045 micromol/L). Biochemical studies implicated a novel irreversible interaction of the inhibitor and AKT involving a critical cysteine residue(s). To examine the role of conserved cysteines in the activation loop (T-loop), we studied mutant AKT1 harboring C296A, C310A, and C296A/C310A. Whereas the ATP-pocket inhibitor, staurosporine, indiscriminately targeted the wild-type and all three mutant-enzymes, the inhibition by lactoquinomycin was drastically diminished in the single mutants C296A and C310A, and completely abolished in the double mutant C296A/C310A. These data strongly implicate the binding of lactoquinomycin to the T-loop cysteines as critical for abrogation of catalysis, and define an unprecedented mechanism of AKT inhibition by a small molecule. Lactoquinomycin inhibited cellular AKT substrate phosphorylation induced by growth factor, loss of PTEN, and myristoylated AKT. The inhibition was substantially attenuated by coexpression of C296A/C310A. Moreover, lactoquinomycin reduced cellular mammalian target of rapamycin signaling and cap-dependent mRNA translation initiation. Our results highlight T-loop targeting as a new strategy for the generation of selective AKT inhibitors.
Collapse
|
105
|
Abstract
There is a renewed interest in the ultimate role of fatty acid synthase (FASN)--a key lipogenic enzyme catalysing the terminal steps in the de novo biogenesis of fatty acids--in cancer pathogenesis. Tumour-associated FASN, by conferring growth and survival advantages rather than functioning as an anabolic energy-storage pathway, appears to necessarily accompany the natural history of most human cancers. A recent identification of cross-talk between FASN and well-established cancer-controlling networks begins to delineate the oncogenic nature of FASN-driven lipogenesis. FASN, a nearly-universal druggable target in many human carcinomas and their precursor lesions, offers new therapeutic opportunities for metabolically treating and preventing cancer.
Collapse
Affiliation(s)
- Javier A Menendez
- Translational Research Unit, Catalan Institute of Oncology (ICO), Health Services Division of Catalonia, Girona Biomedical Research Institute (IdIBGi), Medical Oncology, Josep Trueta University Hospital of Girona, 17,007 Girona, Catalonia, Spain
| | | |
Collapse
|
106
|
Smith KD, Shao MY, Posner MC, Weichselbaum RR. Tumor genotype determines susceptibility to oncolytic herpes simplex virus mutants: strategies for clinical application. Future Oncol 2007; 3:545-56. [DOI: 10.2217/14796694.3.5.545] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Oncolytic Herpes simplex virus -1 (HSV-1) mutants based on deletion of the γ134.5 gene are promising therapies for cancer. Δγ134.5 mutant replication and cytolysis is tumor cell type specific and severely attenuated in normal tissues. The basis for attenuation lies in the activation of the protein kinase R (PKR)-mediated host cellular defense pathway, which inhibits protein synthesis in infected cells. Tumor cells which overexpress MAPK kinase (MEK) activity support robust replication of Δγ134.5 mutants via MEK-mediated inhibition of PKR, resulting in tumor oncolysis. Systemic delivery of γ134.5 mutants may allow selective targeting and destruction of metastases from a broad range of solid human tumors that overexpress MEK. Barriers to systemic HSV-1 oncolytic therapy include innate immunity, adaptive immunity and hepatic adsorption. Immunomodulating agents may overcome innate immunity to HSV-1-based vectors. Preclinical data combined with the pervasiveness of HSV-1 despite widespread immunity suggest that preexisting immunity may not eliminate oncolytic efficacy. In the future, biopsy-determined tumor MEK status may select patients for Δγ134.5 oncolytic therapy.
Collapse
Affiliation(s)
- Kerrington D Smith
- MD Anderson Cancer Center, Department of Surgical Oncology, 1515 Holcombe Blvd. Unit 444, Houston TX 77030, USA
| | - Michael Y Shao
- University of Chicago Medical Center, Department of General Surgery, 5841 S. Maryland Avenue, MC 6040, Chicago, IL 60637, USA
| | - Mitchell C Posner
- University of Chicago Medical Center, 5841 S. Maryland Avenue, MC 5031, Chicago, IL 60637, USA
| | - Ralph R Weichselbaum
- Center for Advanced Medicine 1338, Department of Radiation & Cellular Oncology, 5758 S. Maryland Avenue, MC 9006, Chicago, IL 60637, USA
| |
Collapse
|
107
|
Desrivières S, Kuhn K, Müller J, Gläser M, Laria NCP, Korder J, Sonnentag M, Neumann T, Schwarz J, Schäfer J, Hamon C, Groner B, Prinz T. Comparison of the nuclear proteomes of mammary epithelial cells at different stages of functional differentiation. Proteomics 2007; 7:2019-37. [PMID: 17514683 DOI: 10.1002/pmic.200600994] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
The progression of stem cells to proliferating progenitor cells and finally to a quiescent differentiated state is a hallmark of organ development. This process proceeds through distinct steps and is regulated through cell-cell interactions and by systemically and locally acting factors. We have established a cell culture system which recapitulates features of mammary gland development in vitro and allows the comparison of three characteristic differentiation stages. Cell fate decisions relating to proliferation and differentiation are dependent on the function of proteins in the nucleus. Therefore, we have applied proteomic approaches, including 1- and 2-DE coupled with MS and a gel-free system, called protein sequence tag technology (PST), to assess the changes in the nuclear protein composition during differentiation of mammary epithelial cells. We identified about 250 individual proteins which are present in the nucleus of proliferating and functionally differentiated mammary epithelial cells. We functionally categorised the differentially expressed proteins and identified a multitude of proteins that regulate gene expression at the transcriptional or post-transcriptional level. This analysis greatly enriches our global view of the dynamic changes of nuclear proteins during the development of mammary epithelial cells and suggests models for the control of differentiation-specific protein expression.
Collapse
|
108
|
Affiliation(s)
- Clara Balsano
- Dipartimento di Medicina Interna e Sanità Pubblica (MISP), University of L'Aquila, L'Aquila, Italy.
| | | |
Collapse
|
109
|
McDade SS, Hall PA, Russell SEH. Translational control of SEPT9 isoforms is perturbed in disease. Hum Mol Genet 2007; 16:742-52. [PMID: 17468182 DOI: 10.1093/hmg/ddm003] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
A common feature of the mammalian septin gene family is complex genomic architecture with multiple alternate splice variants. Septin 9 has 18 distinct transcripts encoding 15 polypeptides, with two transcripts (SEPT9_v4 and v4*) encoding the same polypeptide. We have previously reported that the ratio of these distinct transcripts is altered in neoplasia, with the v4 transcript being the usual form in normal cells but v4* becoming predominant in tumours. This led us to ask what the functional differences between these two transcripts might be. The 5'-UTRs of v4 and v4* have distinct 5' ends encoded by exons 1beta (v4) and 1zeta and 2 (v4*) and a common 3' region and initiating ATG encoded within exon 3. Here we show that the two mRNAs are translated with different efficiencies and that cellular stress can alter this. A putative internal ribosome entry site can be identified in the common region of the v4 and v4* 5'-UTRs and translation is modulated by an upstream open-reading frame in the unique region of the v4 5'-UTR. Germline mutations in hereditary neuralgic amyotrophy (HNA) map to the region which is common to the two UTRs. These mutations dramatically enhance the translational efficiency of the v4 5'-UTR, leading to elevated SEPT9_v4 protein under hypoxic conditions. Our data provide a mechanistic insight into how the HNA mutations can alter the fine control of SEPT9_v4 protein and its regulation under physiologically relevant conditions and are consistent with the episodic and stress-induced nature of the clinical features of HNA.
Collapse
Affiliation(s)
- Simon S McDade
- The Centre for Cancer Research and Cell Biology, School of Medicine and Dentistry, Queen's University Belfast, Belfast City Hospital, Belfast, UK
| | | | | |
Collapse
|
110
|
Larsson O, Li S, Issaenko OA, Avdulov S, Peterson M, Smith K, Bitterman PB, Polunovsky VA. Eukaryotic translation initiation factor 4E induced progression of primary human mammary epithelial cells along the cancer pathway is associated with targeted translational deregulation of oncogenic drivers and inhibitors. Cancer Res 2007; 67:6814-24. [PMID: 17638893 DOI: 10.1158/0008-5472.can-07-0752] [Citation(s) in RCA: 123] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Pathologic redirection of translational control by constitutive activation of eukaryotic translation initiation factor 4F (eIF4F), the cap-dependent translation initiation apparatus, is an obligatory step in oncogenesis; however, its mechanism remains undefined. Here, we simulate this pro-oncogenic state by overexpressing eIF4E, the rate-limiting component of eIF4F, in primary human mammary epithelial cells (HMECs) and examine the resultant changes in cell biology and gene expression profiles of total and polyribosome-bound mRNA genome wide. Overexpressed eIF4E rescues primary HMECs from telomere-independent growth arrest and disables checkpoints governing S-phase entry as well as apoptosis in HMECs immortalized by telomerase, imparting cells with proliferative and survival autonomy. Although the transcriptional response to increased eIF4E was modest, the translational response was large, selective, and bidirectional. In addition to translational activation of known and novel eIF4E-responsive oncogenic drivers regulating cell growth and survival, our data unveil previously unrecognized cellular defenses including translational activation of tumor suppressors, translational repression of transcripts enriched with miRNA target sites, and translational modulation of genes governing translation itself. These findings provide insight into the proneoplastic and compensatory mechanisms embedded in the oncogenic translational program. They support a model whereby deregulated eIF4E moves human epithelial cells along the cancer pathway by profoundly altering ribosomal recruitment to cancer-related transcripts, and eIF4E-modified cells counter these potentially oncogenic alterations with a compensatory translational mechanism that mitigates acquisition of malignancy.
Collapse
Affiliation(s)
- Ola Larsson
- Department of Medicine, University of Minnesota, 420 Delaware Street, Minneapolis, MN 55455, USA
| | | | | | | | | | | | | | | |
Collapse
|
111
|
Ji Y, Shah S, Soanes K, Islam MN, Hoxter B, Biffo S, Heslip T, Byers S. Eukaryotic initiation factor 6 selectively regulates Wnt signaling and beta-catenin protein synthesis. Oncogene 2007; 27:755-62. [PMID: 17667944 DOI: 10.1038/sj.onc.1210667] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Eukaryotic initiation factor 6 (eIF6), an essential protein important in ribosome biosynthesis and assembly, was identified as an interacting partner of the beta-catenin C terminus in the yeast two-hybrid assay. Independent studies identified Drosophila eIF6 (DeIF6) in a genetic screen designed to detect new genes involved in the regulation of the Wnt/Wg (wingless) pathway. Ectopic expression of DeIF6 in wing discs results in a Wg phenotype. Expression of eIF6 in adenomatous polyposis coli (APC)-mutant colon cancer cells, which express high levels of active beta-catenin, showed that eIF6 selectively inhibits the Wnt pathway at the level of beta-catenin protein independently of proteasomal degradation. Incorporation of radiolabeled amino acids into beta-catenin was selectively decreased in cells that overexpressed eIF6. A similar inverse relationship of the two proteins was observed in the APC(min/+) mouse intestine, in which beta-catenin levels are very high. Taken together these data reveal a link between eIF6 and Wnt signaling, perhaps at the level of ribosome recycling on beta-catenin mRNA.
Collapse
Affiliation(s)
- Y Ji
- Lombardi Comprehensive Cancer Center, Georgetown University, Washington DC 20057, USA
| | | | | | | | | | | | | | | |
Collapse
|
112
|
Elia A, Constantinou C, Clemens MJ. Effects of protein phosphorylation on ubiquitination and stability of the translational inhibitor protein 4E-BP1. Oncogene 2007; 27:811-22. [PMID: 17653084 DOI: 10.1038/sj.onc.1210678] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
The availability of the eukaryotic polypeptide chain initiation factor 4E (eIF4E) for protein synthesis is regulated by the 4E-binding proteins (4E-BPs), which act as inhibitors of cap-dependent mRNA translation. The ability of the 4E-BPs to sequester eIF4E is regulated by reversible phosphorylation at multiple sites. We show here that, in addition, 4E-BP1 is a substrate for polyubiquitination and that some forms of 4E-BP1 are simultaneously polyubiquitinated and phosphorylated. In Jurkat cells inhibition of proteasomal activity by MG132 enhances the level of hypophosphorylated, unmodified 4E-BP1 but only modestly increases the accumulation of high-molecular-weight, phosphorylated forms of 4E-BP1. In contrast, inhibition of protein phosphatase activity with calyculin A reduces the level of unmodified 4E-BP1 but strongly enhances the amount of phosphorylated, high-molecular-weight 4E-BP1. Turnover measurements in the presence of cycloheximide show that, whereas 4E-BP1 is normally a very stable protein, calyculin A decreases the apparent half-life of the normal-sized protein. Affinity chromatography on m(7)GTP-Sepharose indicates that the larger forms of 4E-BP1 bind very poorly to eIF4E. We suggest that the phosphorylation of 4E-BP1 may play a dual role in the regulation of protein synthesis, both reducing the affinity of 4E-BP1 for eIF4E and promoting the conversion of 4E-BP1 to alternative, polyubiquitinated forms.
Collapse
Affiliation(s)
- A Elia
- Translational Control Group, Division of Basic Medical Sciences, Centre for Molecular and Metabolic Signalling, St George's, University of London, London, UK
| | | | | |
Collapse
|
113
|
Agnelli L, Fabris S, Bicciato S, Basso D, Baldini L, Morabito F, Verdelli D, Todoerti K, Lambertenghi-Deliliers G, Lombardi L, Neri A. Upregulation of translational machinery and distinct genetic subgroups characterise hyperdiploidy in multiple myeloma. Br J Haematol 2007; 136:565-73. [PMID: 17367409 DOI: 10.1111/j.1365-2141.2006.06467.x] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Karyotypic instability, including numerical and structural chromosomal aberrations, represents a distinct feature of multiple myeloma (MM). About 40-50% of patients display hyperdiploidy, defined by recurrent trisomies of non-random chromosomes. To molecularly characterise hyperdiploid (H) and nonhyperdiploid (NH) MM, we analysed the gene expression profiles of 66 primary tumours, and used fluorescence in situ hybridisation to investigate the major chromosomal alterations. The differential expression of 225 genes mainly involved in protein biosynthesis, transcriptional machinery and oxidative phosphorylation distinguished the 28 H-MM from the 38 NH-MM cases. The 204 upregulated genes in H-MM mapped mainly to the chromosomes involved in hyperdiploidy, and the 29% upregulated genes in NH-MM mapped to 16q. The identified transcriptional fingerprint was robustly validated on a publicly available gene expression dataset of 64 MM cases; and the global expression modulation of regions on the chromosomes involved in hyperdiploidy was verified using a self-developed non-parametric statistical method. H-MM could be further divided into two distinct molecular and transcriptional entities, characterised by the presence of trisomy 11 and 1q-extracopies/chromosome 13 deletion respectively. These data reinforce the importance of combining molecular cytogenetics and gene expression profiling to define a genomic framework for the study of MM pathogenesis and clinical management.
Collapse
Affiliation(s)
- Luca Agnelli
- Centro di Genetica Molecolare ed Espressione Genica, Fondazione IRCCS Ospedale Maggiore Policlinico, Mangiagalli e Regina Elena, Milan, Italy
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
114
|
Petz M, Kozina D, Huber H, Siwiec T, Seipelt J, Sommergruber W, Mikulits W. The leader region of Laminin B1 mRNA confers cap-independent translation. Nucleic Acids Res 2007; 35:2473-82. [PMID: 17395640 PMCID: PMC1885646 DOI: 10.1093/nar/gkm096] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Translation initiation of eukaryotic mRNAs generally occurs by cap-dependent ribosome scanning. However, certain mRNAs contain internal ribosome entry sites (IRES) allowing cap-independent translation. Several of these IRES-competent transcripts and their corresponding proteins are involved in tumourigenesis. This study focused on IRES-driven translation control during the epithelial to mesenchymal transition (EMT) of hepatocytes that reflects crucial aspects of carcinoma progression. Expression profiling of EMT revealed Laminin B1 (LamB1) to be translationally upregulated. The 5′-untranslated region (UTR) of LamB1 was potent to direct IRES-dependent mRNA utilization of a bicistronic reporter construct. Stringent assays for cryptic promoter and splice sites showed no aberrantly expressed transcripts, suggesting that the reporter activity provided by the leader region of LamB1 mRNA exclusively depends on IRES. In accordance, LamB1 expression increased upon negative interference with cap-dependent translation by expression of human rhinovirus 2A protease or heat shock of cells. Finally, the enhanced expression of LamB1 during EMT correlated with an elevated IRES activity. Together, these data provide first evidence that the 5′-UTR of LamB1 contains a bona fide IRES that directs translational upregulation of LamB1 during stress conditions and neoplastic progression of hepatocytes.
Collapse
Affiliation(s)
- Michaela Petz
- Department of Medicine I, Division: Institute of Cancer Research, Medical University of Vienna, Borschke-Gasse 8a, A-1090 Vienna, Boehringer Ingelheim Austria, Dr Boehringer Gasse 5-10, A-1120 Vienna and Max F. Perutz Laboratories, University Departments at the Vienna Biocenter, Department of Medical Biochemistry, Medical University of Vienna, Dr Bohr-Gasse 9, A-1030 Vienna, Austria
| | - Daniela Kozina
- Department of Medicine I, Division: Institute of Cancer Research, Medical University of Vienna, Borschke-Gasse 8a, A-1090 Vienna, Boehringer Ingelheim Austria, Dr Boehringer Gasse 5-10, A-1120 Vienna and Max F. Perutz Laboratories, University Departments at the Vienna Biocenter, Department of Medical Biochemistry, Medical University of Vienna, Dr Bohr-Gasse 9, A-1030 Vienna, Austria
| | - Heidemarie Huber
- Department of Medicine I, Division: Institute of Cancer Research, Medical University of Vienna, Borschke-Gasse 8a, A-1090 Vienna, Boehringer Ingelheim Austria, Dr Boehringer Gasse 5-10, A-1120 Vienna and Max F. Perutz Laboratories, University Departments at the Vienna Biocenter, Department of Medical Biochemistry, Medical University of Vienna, Dr Bohr-Gasse 9, A-1030 Vienna, Austria
| | - Tanja Siwiec
- Department of Medicine I, Division: Institute of Cancer Research, Medical University of Vienna, Borschke-Gasse 8a, A-1090 Vienna, Boehringer Ingelheim Austria, Dr Boehringer Gasse 5-10, A-1120 Vienna and Max F. Perutz Laboratories, University Departments at the Vienna Biocenter, Department of Medical Biochemistry, Medical University of Vienna, Dr Bohr-Gasse 9, A-1030 Vienna, Austria
| | - Joachim Seipelt
- Department of Medicine I, Division: Institute of Cancer Research, Medical University of Vienna, Borschke-Gasse 8a, A-1090 Vienna, Boehringer Ingelheim Austria, Dr Boehringer Gasse 5-10, A-1120 Vienna and Max F. Perutz Laboratories, University Departments at the Vienna Biocenter, Department of Medical Biochemistry, Medical University of Vienna, Dr Bohr-Gasse 9, A-1030 Vienna, Austria
| | - Wolfgang Sommergruber
- Department of Medicine I, Division: Institute of Cancer Research, Medical University of Vienna, Borschke-Gasse 8a, A-1090 Vienna, Boehringer Ingelheim Austria, Dr Boehringer Gasse 5-10, A-1120 Vienna and Max F. Perutz Laboratories, University Departments at the Vienna Biocenter, Department of Medical Biochemistry, Medical University of Vienna, Dr Bohr-Gasse 9, A-1030 Vienna, Austria
| | - Wolfgang Mikulits
- Department of Medicine I, Division: Institute of Cancer Research, Medical University of Vienna, Borschke-Gasse 8a, A-1090 Vienna, Boehringer Ingelheim Austria, Dr Boehringer Gasse 5-10, A-1120 Vienna and Max F. Perutz Laboratories, University Departments at the Vienna Biocenter, Department of Medical Biochemistry, Medical University of Vienna, Dr Bohr-Gasse 9, A-1030 Vienna, Austria
- *To whom correspondence should be addressed +43 1 4277 65250+43 1 4277 65239
| |
Collapse
|
115
|
Roux PP, Shahbazian D, Vu H, Holz MK, Cohen MS, Taunton J, Sonenberg N, Blenis J. RAS/ERK signaling promotes site-specific ribosomal protein S6 phosphorylation via RSK and stimulates cap-dependent translation. J Biol Chem 2007; 282:14056-64. [PMID: 17360704 PMCID: PMC3618456 DOI: 10.1074/jbc.m700906200] [Citation(s) in RCA: 572] [Impact Index Per Article: 33.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Converging signals from the mammalian target of rapamycin (mTOR) and phosphoinositide 3-kinase (PI3K) pathways are well established to modulate translation initiation. Less is known regarding the molecular basis of protein synthesis regulated by other inputs, such as agonists of the Ras/extracellular signal-regulated kinase (ERK) signaling cascade. Ribosomal protein (rp) S6 is a component of the 40S ribosomal subunit that becomes phosphorylated at several serine residues upon mitogen stimulation, but the exact molecular mechanisms regulating its phosphorylation and the function of phosphorylated rpS6 is poorly understood. Here, we provide evidence that activation of the p90 ribosomal S6 kinases (RSKs) by serum, growth factors, tumor promoting phorbol esters, and oncogenic Ras is required for rpS6 phosphorylation downstream of the Ras/ERK signaling cascade. We demonstrate that while ribosomal S6 kinase 1 (S6K1) phosphorylates rpS6 at all sites, RSK exclusively phosphorylates rpS6 at Ser(235/236) in vitro and in vivo using an mTOR-independent mechanism. Mutation of rpS6 at Ser(235/236) reveals that phosphorylation of these sites promotes its recruitment to the 7-methylguanosine cap complex, suggesting that Ras/ERK signaling regulates assembly of the translation preinitiation complex. These data demonstrate that RSK provides an mTOR-independent pathway linking the Ras/ERK signaling cascade to the translational machinery.
Collapse
Affiliation(s)
- Philippe P Roux
- Department of Pathology and Cell Biology, Institut de Recherche en Immunologie et en Cancérologie (IRIC), Université de Montréal, Montréal, Québec, Canada.
| | | | | | | | | | | | | | | |
Collapse
|
116
|
Rogers SJ, Box C, Harrington KJ, Nutting C, Rhys-Evans P, Eccles SA. The phosphoinositide 3-kinase signalling pathway as a therapeutic target in squamous cell carcinoma of the head and neck. Expert Opin Ther Targets 2007; 9:769-90. [PMID: 16083342 DOI: 10.1517/14728222.9.4.769] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Squamous cell carcinoma of the head and neck (SCCHN) is associated with high morbidity and mortality. Despite significant surgical advances and refinement in the delivery of chemotherapy and radiotherapy, prognosis has improved little in recent decades. Better local control has led to the late presentation of distant metastases and novel therapeutic agents are urgently required to prevent relapse, control disseminated disease and thus improve survival. PIK3CA encodes the p110alpha isoform of phosphoinositide 3-kinase (PI3-K) and is important in SCCHN, aberrations in its activity occurring early in the oncogenic process. PI3-K signalling promotes cell survival, proliferation, invasion and angiogenesis, all contributing to tumour progression. Activation of the PI3-K pathway may also mediate resistance to chemotherapy, radiotherapy and novel therapeutic agents such as epidermal growth factor receptor inhibitors. Elements of this signalling matrix, therefore, offer attractive therapeutic targets in SCCHN as inhibition of many malignant characteristics, as well as sensitisation to multiple treatment modalities, could be anticipated.
Collapse
Affiliation(s)
- Susanne J Rogers
- Cancer Research UK Centre for Cancer Therapeutics, Tumour Biology and Metastasis Team, Institute of Cancer Research, McElwain Laboratories, Cotswold Rd, Belmont, Sutton, Surrey, SM2 5NG, UK
| | | | | | | | | | | |
Collapse
|
117
|
Oulhen N, Salaün P, Cosson B, Cormier P, Morales J. After fertilization of sea urchin eggs, eIF4G is post-translationally modified and associated with the cap-binding protein eIF4E. J Cell Sci 2007; 120:425-34. [PMID: 17213333 DOI: 10.1242/jcs.03339] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Release of eukaryotic initiation factor 4E (eIF4E) from its translational repressor eIF4E-binding protein (4E-BP) is a crucial event for the first mitotic division following fertilization of sea urchin eggs. Finding partners of eIF4E following fertilization is crucial to understand how eIF4E functions during this physiological process. The isolation and characterization of cDNA encoding Sphaerechinus granularis eIF4G (SgIF4G) are reported. mRNA of SgIF4G is present as a single 8.5-kb transcript in unfertilized eggs, suggesting that only one ortholog exists in echinoderms. The longest open reading frame predicts a sequence of 5235 nucleotides encoding a deduced polypeptide of 1745 amino acids with a predicted molecular mass of 192 kDa. Among highly conserved domains, SgIF4G protein possesses motifs that correspond to the poly(A) binding protein and eIF4E protein-binding sites. A specific polyclonal antibody was produced and used to characterize the SgIF4G protein in unfertilized and fertilized eggs by SDS-PAGE and western blotting. Multiple differentially migrating bands representing isoforms of sea urchin eIF4G are present in unfertilized eggs. Fertilization triggers modifications of the SgIF4G isoforms and rapid formation of the SgIF4G-eIF4E complex. Whereas rapamycin inhibits the formation of the SgIF4G-eIF4E complex, modification of these SgIF4G isoforms occurs independently from the rapamycin-sensitive pathway. Microinjection of a peptide corresponding to the eIF4E-binding site derived from the sequence of SgIF4G into unfertilized eggs affects the first mitotic division of sea urchin embryos. Association of SgIF4G with eIF4E is a crucial event for the onset of the first mitotic division following fertilization, suggesting that cap-dependent translation is highly regulated during this process. This hypothesis is strengthened by the evidence that microinjection of the cap analog m(7)GDP into unfertilized eggs inhibits the first mitotic division.
Collapse
Affiliation(s)
- Nathalie Oulhen
- Université Pierre et Marie Curie-Paris6, UMR 7150, Equipe Cycle Cellulaire et Développement and CNRS, UMR 7150, Station Biologique de Roscoff, 29682 Roscoff CEDEX, France
| | | | | | | | | |
Collapse
|
118
|
Edgerton ME, Fisher DH, Tang L, Frey LJ, Chen Z. Data Mining for Gene Networks Relevant to Poor Prognosis in Lung Cancer via Backward-Chaining Rule Induction. Cancer Inform 2007. [DOI: 10.1177/117693510700300016] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
We use Backward Chaining Rule Induction (BCRI), a novel data mining method for hypothesizing causative mechanisms, to mine lung cancer gene expression array data for mechanisms that could impact survival. Initially, a supervised learning system is used to generate a prediction model in the form of “IF <conditions> THEN <outcome>” style rules. Next, each antecedent (i.e. an IF condition) of a previously discovered rule becomes the outcome class for subsequent application of supervised rule induction. This step is repeated until a termination condition is satisfied. “Chains” of rules are created by working backward from an initial condition (e.g. survival status). Through this iterative process of “backward chaining,” BCRI searches for rules that describe plausible gene interactions for subsequent validation. Thus, BCRI is a semi-supervised approach that constrains the search through the vast space of plausible causal mechanisms by using a top-level outcome to kick-start the process. We demonstrate the general BCRI task sequence, how to implement it, the validation process, and how BCRI-rules discovered from lung cancer microarray data can be combined with prior knowledge to generate hypotheses about functional genomics.
Collapse
Affiliation(s)
- Mary E. Edgerton
- Department of Pathology and Department of Biomedical Informatics, Vanderbilt University, currently Department of Anatomic Pathology, University of Texas, M.D. Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, TX 77030
| | - Douglas H. Fisher
- Department of Electrical Engineering and Computer Science, Vanderbilt University, Salt Lake City, UT 84112
| | - Lianhong Tang
- Vanderbilt-Ingram Cancer Center, currently Department of Biomedical Informatics, Vanderbilt University, Salt Lake City, UT 84112
| | - Lewis J. Frey
- Department of Biomedical Informatics, Vanderbilt University, currently Department of Biomedical Informatics, University of Utah School of Medicine, Salt Lake City, UT 84112
| | - Zhihua Chen
- Department of Electrical Engineering and Computer Science, Vanderbilt University, currently Department of Interdisciplinary Oncology, H. Lee Moffitt Cancer Center and Research Institute, SRB3,12902 Magnolia Drive, Tampa, FL 33612
| |
Collapse
|
119
|
Abstract
There is currently a high level of interest in signalling through the mammalian target of rapamycin (mTOR). This reflects both its key role in many cell functions and its involvement in disease states such as cancers. The best understood targets for mTOR signalling are proteins involved in controlling the translational machinery, including the ribosomal protein S6 kinases and proteins that regulate the initiation and elongation phases of translation. Indeed, there is compelling evidence that at least one of these targets of mTOR (eukaryotic initiation factor eIF4E) plays a key role in tumorigenesis. It is regulated through the mTOR-dependent phosphorylation of inhibitory proteins such as eIF4E-binding protein 1. Thus, targeting mTOR signalling may be an effective anticancer strategy, in at least a significant subset of tumours. Not all effects of mTOR are sensitive to the classical anti-mTOR drug rapamycin, and this compound also interferes with other processes besides eIF4E function. Developing new approaches to targeting mTOR for cancer therapy requires more detailed knowledge of signalling downstream of mTOR. Such advances are likely to come from further work to understand the regulation of mTOR targets such as components of the translational apparatus.
Collapse
Affiliation(s)
- J Averous
- Unité de Nutrition Humaine, INRA de Theix, Saint Genès Champanelle, France
| | | |
Collapse
|
120
|
Campagne F, Skrabanek L. Mining expressed sequence tags identifies cancer markers of clinical interest. BMC Bioinformatics 2006; 7:481. [PMID: 17078886 PMCID: PMC1635568 DOI: 10.1186/1471-2105-7-481] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2006] [Accepted: 11/01/2006] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Gene expression data are a rich source of information about the transcriptional dis-regulation of genes in cancer. Genes that display differential regulation in cancer are a subtype of cancer biomarkers. RESULTS We present an approach to mine expressed sequence tags to discover cancer biomarkers. A false discovery rate analysis suggests that the approach generates less than 22% false discoveries when applied to combined human and mouse whole genome screens. With this approach, we identify the 200 genes most consistently differentially expressed in cancer (called HM200) and proceed to characterize these genes. When used for prediction in a variety of cancer classification tasks (in 24 independent cancer microarray datasets, 59 classifications total), we show that HM200 and the shorter gene list HM100 are very competitive cancer biomarker sets. Indeed, when compared to 13 published cancer marker gene lists, HM200 achieves the best or second best classification performance in 79% of the classifications considered. CONCLUSION These results indicate the existence of at least one general cancer marker set whose predictive value spans several tumor types and classification types. Our comparison with other marker gene lists shows that HM200 markers are mostly novel cancer markers. We also identify the previously published Pomeroy-400 list as another general cancer marker set. Strikingly, Pomeroy-400 has 27 genes in common with HM200. Our data suggest that a core set of genes are responsive to the deregulation of pathways involved in tumorigenesis in a variety of tumor types and that these genes could serve as transcriptional cancer markers in applications of clinical interest. Finally, our study suggests new strategies to select and evaluate cancer biomarkers in microarray studies.
Collapse
Affiliation(s)
- Fabien Campagne
- Institute for Computational Biomedicine and Dept. of Physiology and Biophysics, Weill Medical College of Cornell University; 1300 York Ave; New York, NY 10021, USA
| | - Lucy Skrabanek
- Institute for Computational Biomedicine and Dept. of Physiology and Biophysics, Weill Medical College of Cornell University; 1300 York Ave; New York, NY 10021, USA
| |
Collapse
|
121
|
Coulouarn C, Gomez-Quiroz LE, Lee JS, Kaposi-Novak P, Conner EA, Goldina TA, Onishchenko GE, Factor VM, Thorgeirsson SS. Oncogene-specific gene expression signatures at preneoplastic stage in mice define distinct mechanisms of hepatocarcinogenesis. Hepatology 2006; 44:1003-11. [PMID: 17006931 DOI: 10.1002/hep.21293] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
We applied a genome-wide microarray analysis to three transgenic mouse models of liver cancer in which targeted overexpression of c-Myc, E2f1, and a combination of the two was driven by the albumin promoter. Although gene expression profiles in HCC derived in all three transgenic lines were highly similar, oncogene-specific gene expression signatures were identified at an early dysplastic stage of hepatocarcinogenesis. Overexpression of E2f1 was associated with a strong alteration in lipid metabolism, and Srebp1 was identified as a candidate transcription factor responsible for lipogenic enzyme induction. The molecular signature of c-Myc overexpression included the induction of more than 60 genes involved in the translational machinery that correlated with an increase in liver mass. In contrast, the combined activity of c-Myc and E2f1 specifically enhanced the expression of genes involved in mitochondrial metabolism--particularly the components of the respiratory chain--and correlated with an increased ATP synthesis. Thus, the results suggest that E2f1, c-Myc, and their combination may promote liver tumor development by distinct mechanisms. In conclusion, determination of tissue-specific oncogene expression signatures might be useful to identify conserved expression modules in human cancers.
Collapse
Affiliation(s)
- Cédric Coulouarn
- Laboratory of Experimental Carcinogenesis, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | | | | | | | | | | | | | | | | |
Collapse
|
122
|
Jeffrey IW, Elia A, Bornes S, Tilleray VJ, Gengatharan K, Clemens MJ. Interferon-alpha induces sensitization of cells to inhibition of protein synthesis by tumour necrosis factor-related apoptosis-inducing ligand. FEBS J 2006; 273:3698-708. [PMID: 16911520 DOI: 10.1111/j.1742-4658.2006.05374.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Tumour cells are often sensitized by interferons to the effects of tumour necrosis factor-alpha-related apoptosis-inducing ligand (TRAIL). We have demonstrated previously that TRAIL has an inhibitory effect on protein synthesis [Jeffrey IW, Bushell M, Tilleray VJ, Morley S & Clemens MJ (2002) Cancer Res62, 2272-2280] and we have therefore examined the consequences of prior interferon-alpha treatment for the sensitivity of translation to inhibition by TRAIL. Interferon treatment alone has only a minor effect on protein synthesis but it sensitizes both MCF-7 cells and HeLa cells to the downregulation of translation by TRAIL. The inhibition of translation is characterized by increased phosphorylation of the alpha subunit of eukaryotic initiation factor eIF2 and dephosphorylation of the eIF4E-binding protein 4E-BP1. Both of these effects, as well as the decrease in overall protein synthesis, require caspase-8 activity, although they precede overt apoptosis by several hours. Interferon-alpha enhances the level and/or the extent of activation of caspase-8 by TRAIL, thus providing a likely explanation for the sensitization of cells to the inhibition of translation.
Collapse
Affiliation(s)
- Ian W Jeffrey
- Translational Control Group, Centre for Molecular and Metabolic Signalling, Division of Basic Medical Sciences, St George's, University of London, UK
| | | | | | | | | | | |
Collapse
|
123
|
Gelev V, Aktas H, Marintchev A, Ito T, Frueh D, Hemond M, Rovnyak D, Debus M, Hyberts S, Usheva A, Halperin J, Wagner G. Mapping of the auto-inhibitory interactions of protein kinase R by nuclear magnetic resonance. J Mol Biol 2006; 364:352-63. [PMID: 17011579 PMCID: PMC3622519 DOI: 10.1016/j.jmb.2006.08.077] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2006] [Revised: 08/24/2006] [Accepted: 08/28/2006] [Indexed: 11/23/2022]
Abstract
The dsRNA-dependent protein kinase (PKR) is a key mediator of the anti-viral and anti-proliferative effects of interferon. Unphosphorylated PKR is characterized by inhibitory interactions between the kinase and RNA binding domains (RBDs), but the structural details of the latent state and its unraveling during activation are not well understood. To study PKR regulation by NMR we assigned a large portion of the backbone resonances of the catalytically inactive K296R kinase domain, and performed (15)N-heteronuclear single quantum coherence (HSQC) titrations of this kinase domain with the RBDs. Chemical shift perturbations in the kinase indicate that RBD2 binds to the substrate eIF2alpha docking site in the kinase C-lobe. Consistent with these results, a mutation in the eIF2alpha docking site, F495A, displays weaker interactions with the RBD. The full-length RBD1+2 binds more strongly to the kinase domain than RBD2 alone. The observed chemical shift changes extend from the eIF2alpha binding site into the kinase N-lobe and inside the active site, consistent with weak interactions between the N-terminal part of the RBD and the kinase.
Collapse
Affiliation(s)
- Vladimir Gelev
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, 240 Longwood Ave, Boston, MA 02115
| | - Husseyin Aktas
- Laboratory for Membrane Transport, Harvard Medical School, 1 Kendall Square, Cambridge, MA 02139
| | - Assen Marintchev
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, 240 Longwood Ave, Boston, MA 02115
| | - Takuhiro Ito
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, 240 Longwood Ave, Boston, MA 02115
| | - Dominique Frueh
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, 240 Longwood Ave, Boston, MA 02115
| | - Michael Hemond
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, 240 Longwood Ave, Boston, MA 02115
| | - David Rovnyak
- Chemistry Department, Bucknell University, Lewisburg, PA 17837
| | - Miriam Debus
- Laboratory for Membrane Transport, Harvard Medical School, 1 Kendall Square, Cambridge, MA 02139
| | - Sven Hyberts
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, 240 Longwood Ave, Boston, MA 02115
| | - Anny Usheva
- Department of Medicine, Beth Israel Deaconnes Medical Center, 99 Brookline Ave, Boston, MA 02215
| | - Jose Halperin
- Laboratory for Membrane Transport, Harvard Medical School, 1 Kendall Square, Cambridge, MA 02139
| | - Gerhard Wagner
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, 240 Longwood Ave, Boston, MA 02115
- *Address correspondence to
| |
Collapse
|
124
|
Ong CK, Leong C, Tan PH, Van T, Huynh H. The role of 5′ untranslated region in translational suppression of OKL38 mRNA in hepatocellular carcinoma. Oncogene 2006; 26:1155-65. [PMID: 16924236 DOI: 10.1038/sj.onc.1209896] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Hepatocellular carcinoma (HCC) is the sixth most common cancer worldwide. OKL38 is a pregnancy-induced growth inhibitory gene and its expression is lost in various breast cancer cell lines and kidney tumor. To determine the role of OKL38 expression in HCC, we investigated its expression in various HCC samples and liver cancer cell lines. Western blot analysis revealed that OKL38 protein was absent or reduced in 64.2% (18 of 28) of the HCCs examined and four liver cancer cell lines. Immunohistochemistry study demonstrated that OKL38 protein was undetectable in 41.3% (38 of 92) of HCC, whereas 39.1% (36 of 92) of HCC showed low expression of the protein. Lost or reduced expression level of OKL38 protein was significantly correlated to high tumor stages in HCC (P=0.0042). Overexpression of the OKL38 caused cell death in Chang liver cells. 5' Untranslated region (5'UTR) deletion studies demonstrated that OKL38 was downregulated via translation suppression associated with the 5'UTR of its mRNA. Taken together, the 5'UTRs of OKL38 might play an important role in downregulation of its protein and the absence of OKL38 could lead to the development or progression of HCC.
Collapse
Affiliation(s)
- C K Ong
- Laboratory of Molecular Endocrinology, Division of Cellular and Molecular Research, National Cancer Centre of Singapore, Singapore, Singapore
| | | | | | | | | |
Collapse
|
125
|
Ranganathan AC, Adam AP, Aguirre-Ghiso JA. Opposing roles of mitogenic and stress signaling pathways in the induction of cancer dormancy. Cell Cycle 2006; 5:1799-807. [PMID: 16929185 PMCID: PMC2517052 DOI: 10.4161/cc.5.16.3109] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Cancer dormancy is a poorly understood stage of cancer progression. However, the ability to control this step of the disease offers novel therapeutic opportunities. Here we summarize recent findings that implicate the extracellular matrix and adhesion receptor signaling in the escape or induction of tumor dormancy. We further review evidence suggesting that imbalances in the activity ratio of ERK to p38 signaling may determine the fate (i.e., tumorigenicity vs. dormancy) of different carcinoma cells. Special attention is placed on the mechanisms that p38 signaling regulates during the induction of dormancy and how modulation of these pathways may offer a therapeutic opportunity. We also review evidence for a novel drug-resistance mechanism in dormant tumor cells that when blocked may enable killing of dormant tumor cells. Finally, we explore the notion that dormancy of tumor cells may be the result of a selective adaptive response that allows disseminated tumor cells to pause their growth and cope with stress signaling imposed by dissemination and/or treatment until growth can be restored.
Collapse
Affiliation(s)
| | | | - Julio A. Aguirre-Ghiso
- Correspondence to: Julio A. Aguirre-Ghiso; Gen*NY*Sis Center For Excellence in Cancer Genomics, Room 216; 1 Discovery Drive; Rensselaer, New York 12144-3456 USA; Tel.: 518.591.7152; Fax: 518.591.7151;
| |
Collapse
|
126
|
Connolly E, Braunstein S, Formenti S, Schneider RJ. Hypoxia inhibits protein synthesis through a 4E-BP1 and elongation factor 2 kinase pathway controlled by mTOR and uncoupled in breast cancer cells. Mol Cell Biol 2006; 26:3955-65. [PMID: 16648488 PMCID: PMC1489005 DOI: 10.1128/mcb.26.10.3955-3965.2006] [Citation(s) in RCA: 177] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Hypoxia is a state of low oxygen availability that limits tumor growth. The mechanism of protein synthesis inhibition by hypoxia and its circumvention by transformation are not well understood. Hypoxic breast epithelial cells are shown to downregulate protein synthesis by inhibition of the kinase mTOR, which suppresses mRNA translation through a novel mechanism mitigated in transformed cells: disruption of proteasome-targeted degradation of eukaryotic elongation factor 2 (eEF2) kinase and activation of the regulatory protein 4E-BP1. In transformed breast epithelial cells under hypoxia, the mTOR and S6 kinases are constitutively activated and the mTOR negative regulator tuberous sclerosis complex 2 (TSC2) protein fails to function. Gene silencing of 4E-BP1 and eEF2 kinase or TSC2 confers resistance to hypoxia inhibition of protein synthesis in immortalized breast epithelial cells. Breast cancer cells therefore acquire resistance to hypoxia by uncoupling oxygen-responsive signaling pathways from mTOR function, eliminating inhibition of protein synthesis mediated by 4E-BP1 and eEF2.
Collapse
MESH Headings
- Adaptor Proteins, Signal Transducing/genetics
- Adaptor Proteins, Signal Transducing/metabolism
- Blotting, Western
- Breast Neoplasms/genetics
- Breast Neoplasms/metabolism
- Breast Neoplasms/pathology
- Carcinoma, Intraductal, Noninfiltrating/metabolism
- Carcinoma, Intraductal, Noninfiltrating/pathology
- Cell Cycle Proteins
- Cell Line, Transformed
- Cell Line, Tumor
- Enzyme Activation
- Female
- Gene Silencing
- Humans
- Hypoxia/physiopathology
- Methionine/metabolism
- Peptide Elongation Factor 2/genetics
- Peptide Elongation Factor 2/metabolism
- Phosphoproteins/genetics
- Phosphoproteins/metabolism
- Phosphorylation
- Precipitin Tests
- Protein Kinases/physiology
- RNA Interference
- RNA, Small Interfering/metabolism
- Retroviridae/genetics
- Ribosomal Protein S6 Kinases/metabolism
- Signal Transduction
- Sulfur Radioisotopes
- TOR Serine-Threonine Kinases
Collapse
Affiliation(s)
- Eileen Connolly
- Department of Microbiology, New York University School of Medicine, New York, New York 10016, USA
| | | | | | | |
Collapse
|
127
|
Oulhen N, Cormier P. [eIF4E and developmental decisions: when translation drives the development]. Med Sci (Paris) 2006; 22:507-13. [PMID: 16687119 DOI: 10.1051/medsci/2006225507] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Regulation of mRNA translation is an important regulatory step in gene expression. During embryonic development, mRNA translation is tightly regulated to produce the protein at the right place, at the right time. The eukaryotic initiation factor 4E (eIF4E) is a major target for the regulation of cap-dependent translation, that plays a key role during embryogenesis including gametogenesis, fertilization and establishment of embryonic axes. In this review, we describe recent advances illustrating the importance of the translational regulator eIF4E and its partners in developmental decisions. double dagger.
Collapse
Affiliation(s)
- Nathalie Oulhen
- Station Biologique de Roscoff, Cycle Cellulaire et Développement, Unité Mer et Santé (UMR 7150), Université Pierre-et-Marie Curie (EI 37), Centre National de la Recherche Scientifique, Institut National des Sciences de l'Univers, Roscoff, France
| | | |
Collapse
|
128
|
Wang H, Zhao LN, Li KZ, Ling R, Li XJ, Wang L. Overexpression of ribosomal protein L15 is associated with cell proliferation in gastric cancer. BMC Cancer 2006; 6:91. [PMID: 16608517 PMCID: PMC1459873 DOI: 10.1186/1471-2407-6-91] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2006] [Accepted: 04/11/2006] [Indexed: 01/28/2023] Open
Abstract
Background Ribosomal proteins are the components of ribosome, which also exhibit various secondary functions in DNA repair, apoptosis, drug resistance and proliferation. In our previous study of microarray, ribosomal protein L15 (RPL15) was identified as an upregulated gene in gastric cancer. Methods We investigated the expression of ribosomal protein L15 in gastric cancer and the effect of RPL15 on proliferation of gastric cancer. Results It was found that the expression of RPL15 was markedly up-regulated in gastric cancer tissues. RPL15 was also highly expressed in gastric cancer cell lines AGS, MKN45, MKN28, SGC7901 and KATOIII. Inhibition of RPL15 expression by siRNA vector transfection suppressed the growth of SGC7901 cells significantly, which was independent of the expression of Cyclin D1 and B1. Down-regulation of RPL15 expression inhibited SGC7901 cell growth in soft agar and its tumorigenicity in nude mice. Conclusion RPL15 promotes cell proliferation and may be a potential target for anticancer therapy of gastric cancer.
Collapse
Affiliation(s)
- Hui Wang
- Department of Vascular and Endocrine Surgery, Xijing Hospital, the Fourth Military Medical University, 17 Changle Western Road, Xi'an 710032, China
| | - Li-Na Zhao
- State Key Laboratory of Cancer Biology & Institute of Digestive Diseases, Xijing Hospital, the Fourth Military Medical University, 17 Changle Western Road, Xi'an 710032, China
| | - Kai-Zong Li
- Department of Hepatobiliary Surgery, Xijing Hospital, the Fourth Military Medical University, 17 Changle Western Road, Xi'an 710032, China
| | - Rui Ling
- Department of Vascular and Endocrine Surgery, Xijing Hospital, the Fourth Military Medical University, 17 Changle Western Road, Xi'an 710032, China
| | - Xiao-Jun Li
- Department of Vascular and Endocrine Surgery, Xijing Hospital, the Fourth Military Medical University, 17 Changle Western Road, Xi'an 710032, China
| | - Ling Wang
- Department of Vascular and Endocrine Surgery, Xijing Hospital, the Fourth Military Medical University, 17 Changle Western Road, Xi'an 710032, China
| |
Collapse
|
129
|
Hizli AA, Black AR, Pysz MA, Black JD. Protein kinase C alpha signaling inhibits cyclin D1 translation in intestinal epithelial cells. J Biol Chem 2006; 281:14596-603. [PMID: 16556598 DOI: 10.1074/jbc.m601959200] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Cyclin D1 is a key regulator of cell proliferation, acting as a mitogen sensor and linking extracellular signaling to the cell cycle machinery. Strict control of cyclin D1 levels is critical for maintenance of tissue homeostasis. We have reported previously that protein kinase C alpha (PKCalpha), a negative regulator of cell growth in the intestinal epithelium, promotes rapid down-regulation of cyclin D1 (Frey, M. R., Clark, J. A., Leontieva, O., Uronis, J. M., Black, A. R., and Black, J. D. (2000) J. Cell Biol. 151, 763-778). The current study explores the mechanisms underlying PKCalpha-induced loss of cyclin D1 protein in non-transformed intestinal epithelial cells. Our findings exclude several mechanisms previously implicated in down-regulation of cyclin D1 during cell cycle exit/differentiation, including alterations in cyclin D1 mRNA expression and protein turnover. Instead, we identify PKCalpha as a novel repressor of cyclin D1 translation, acting at the level of cap-dependent initiation. Inhibition of cyclin D1 translation initiation is mediated by PKCalpha-induced hypophosphorylation/activation of the translational suppressor 4E-BP1, association of 4E-BP1 with the mRNA cap-binding protein eIF4E, and sequestration of cyclin D1 mRNA in 4E-BP1-associated complexes. Together, these post-transcriptional effects ensure rapid disappearance of the potent mitogenic molecule cyclin D1 during PKCalpha-induced cell cycle withdrawal in the intestinal epithelium.
Collapse
Affiliation(s)
- A Asli Hizli
- Department of Pharmacology and Therapeutics, Roswell Park Cancer Institute, Elm and Carlton Streets, Buffalo, NY 14263, USA
| | | | | | | |
Collapse
|
130
|
Kårehed K, Dimberg A, Dahl S, Nilsson K, Oberg F. IFN-gamma-induced upregulation of Fcgamma-receptor-I during activation of monocytic cells requires the PKR and NFkappaB pathways. Mol Immunol 2006; 44:615-24. [PMID: 16516295 DOI: 10.1016/j.molimm.2006.01.013] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2005] [Revised: 01/19/2006] [Accepted: 01/21/2006] [Indexed: 01/22/2023]
Abstract
Interferon (IFN)-gamma is a potent activator of macrophages, increasing the cells capacity to perform specific functions during inflammation and immune response. In this report we use IFN-gamma-induced upregulation of the high affinity receptor for IgG (FcgammaRI/CD64) in the human monocytic cell line U-937 as a model for monocytic activation. We show that upregulation of FcgammaRI is dependent on signals mediated by the dsRNA-dependent kinase PKR, and the transcription factor NFkappaB. Silencing of PKR expression by siRNA or inhibition of PKR by 2-aminopurine (2-AP) potently blocks the IFN-gamma-induced transcriptional activation of the FcgammaRI promoter. We find that the serine 727 phosphorylation of Stat1, required for full IFN-gamma-induced FcgammaRI promoter activity, is dependent on PKR. We further show that IFN-gamma induction of FcgammaRI upregulation is dependent on the NFkappaB pathway, as evidenced by inhibition of NFkappaB using a phosphorylation defective IkappaBalpha (S32A/S36A) mutant, or inhibiting the IkappaB-kinase (IKK) by treatment with BMS345541. Our results suggest that IFN-gamma-induced increase of FcgammaRI expression requires the integration of two signalling events: PKR-dependent Stat1 serine 727 phosphorylation, and activation of NFkappaB.
Collapse
Affiliation(s)
- Karin Kårehed
- Department of Genetics and Pathology, Rudbeck Laboratory, Uppsala University, SE-751 85 Uppsala, Sweden
| | | | | | | | | |
Collapse
|
131
|
Smith KD, Mezhir JJ, Bickenbach K, Veerapong J, Charron J, Posner MC, Roizman B, Weichselbaum RR. Activated MEK suppresses activation of PKR and enables efficient replication and in vivo oncolysis by Deltagamma(1)34.5 mutants of herpes simplex virus 1. J Virol 2006; 80:1110-20. [PMID: 16414988 PMCID: PMC1346955 DOI: 10.1128/jvi.80.3.1110-1120.2006] [Citation(s) in RCA: 88] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Herpes simplex virus mutants lacking the gamma(1)34.5 gene are not destructive to normal tissues but are potent cytolytic agents in human tumor cells in which the activation of double-stranded RNA-dependent protein kinase (PKR) is suppressed. Thus, replication of a Deltagamma(1)34.5 mutant (R3616) in 12 genetically defined cancer cell lines correlates with suppression of PKR but not with the genotype of RAS. Extensive analyses of two cell lines transduced with either dominant negative MEK (dnMEK) or constitutively active MEK (caMEK) indicated that in R3616 mutant-infected cells dnMEK enabled PKR activation and decreased virus yields, whereas caMEK suppressed PKR and enabled better viral replication and cell destruction in transduced cells in vitro or in mouse xenografts. The results indicate that activated MEK mediates the suppression of PKR and that the status of MEK predicts the ability of Deltagamma(1)34.5 mutant viruses to replicate in and destroy tumor cells.
Collapse
Affiliation(s)
- Kerrington D Smith
- Department of Radiation and Cellular Oncology, The University of Chicago Hospitals, Center for Advanced Medicine, Room 1329, Mail Code 9006, 5758 South Maryland Avenue, Chicago, IL 60637, USA
| | | | | | | | | | | | | | | |
Collapse
|
132
|
Le Breton M, Cormier P, Bellé R, Mulner-Lorillon O, Morales J. Translational control during mitosis. Biochimie 2006; 87:805-11. [PMID: 15951098 DOI: 10.1016/j.biochi.2005.04.014] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2005] [Revised: 02/09/2005] [Accepted: 04/29/2005] [Indexed: 10/25/2022]
Abstract
Translation is now recognized as an important process in the regulation of gene expression. During the cell cycle, translation is tightly regulated. Protein synthesis is necessary for entry into and progression through mitosis and conversely, modifications of translational activity are observed during the cell cycle. This review focuses on translational control during mitosis (or M-phase) and the role of CDK1/cyclin B, the universal cell cycle regulator implicated in the G2/M transition, in protein synthesis regulation.
Collapse
Affiliation(s)
- Magali Le Breton
- Equipe Cycle Cellulaire et Développement, UMR 7150 CNRS/UPMC, Station Biologique de Roscoff, BP 74, 29682 Roscoff cedex, France
| | | | | | | | | |
Collapse
|
133
|
Shmulevitz M, Marcato P, Lee PWK. Unshackling the links between reovirus oncolysis, Ras signaling, translational control and cancer. Oncogene 2005; 24:7720-8. [PMID: 16299532 DOI: 10.1038/sj.onc.1209041] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Reovirus has an inherent preference for replicating in cells with dysregulated growth factor signaling cascades that comprise Ras activation. Precisely how reovirus exploits the host cell Ras pathway is unclear, but there is evidence suggesting that activated Ras signaling is important for efficient viral protein synthesis. Defining the molecular mechanism of reovirus oncolysis will shed light on reovirus replication and important aspects of cellular transformation, Ras signaling cascades and regulation of protein translation.
Collapse
Affiliation(s)
- Maya Shmulevitz
- Department of Microbiology and Immunology, Dalhousie University, 7P Sir Charles Tupper Medical Building, Halifax, NS, Canada
| | | | | |
Collapse
|
134
|
Parato KA, Senger D, Forsyth PAJ, Bell JC. Recent progress in the battle between oncolytic viruses and tumours. Nat Rev Cancer 2005; 5:965-76. [PMID: 16294217 DOI: 10.1038/nrc1750] [Citation(s) in RCA: 406] [Impact Index Per Article: 21.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
In the past 5 years, the field of oncolytic virus research has matured significantly and is moving past the stage of being a laboratory novelty into a new era of preclinical and clinical trials. What have recent anticancer trials of oncolytic viruses taught us about this exciting new line of therapeutics?
Collapse
Affiliation(s)
- Kelley A Parato
- Centre for Cancer Therapeutics, Ottawa Health Research Institute, 503 Smyth Road, Ottawa, Ontario, Canada K1H 8L6
| | | | | | | |
Collapse
|
135
|
Dar AC, Dever TE, Sicheri F. Higher-order substrate recognition of eIF2alpha by the RNA-dependent protein kinase PKR. Cell 2005; 122:887-900. [PMID: 16179258 DOI: 10.1016/j.cell.2005.06.044] [Citation(s) in RCA: 292] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2005] [Revised: 05/03/2005] [Accepted: 06/28/2005] [Indexed: 11/18/2022]
Abstract
In response to binding viral double-stranded RNA byproducts within a cell, the RNA-dependent protein kinase PKR phosphorylates the alpha subunit of the translation initiation factor eIF2 on a regulatory site, Ser51. This triggers the general shutdown of protein synthesis and inhibition of viral propagation. To understand the basis for substrate recognition by and the regulation of PKR, we determined X-ray crystal structures of the catalytic domain of PKR in complex with eIF2alpha. The structures reveal that eIF2alpha binds to the C-terminal catalytic lobe while catalytic-domain dimerization is mediated by the N-terminal lobe. In addition to inducing a local unfolding of the Ser51 acceptor site in eIF2alpha, its mode of binding to PKR affords the Ser51 site full access to the catalytic cleft of PKR. The generality and implications of the structural mechanisms uncovered for PKR to the larger family of four human eIF2alpha protein kinases are discussed.
Collapse
Affiliation(s)
- Arvin C Dar
- Program in Molecular Biology and Cancer, Samuel Lunenfeld Research Institute, Mount Sinai Hospital, 600 University Avenue, Toronto, Ontario M5G 1X5, Canada
| | | | | |
Collapse
|
136
|
Alisi A, Mele R, Spaziani A, Tavolaro S, Palescandolo E, Balsano C. Thr 446 phosphorylation of PKR by HCV core protein deregulates G2/M phase in HCC cells. J Cell Physiol 2005; 205:25-31. [PMID: 15880455 DOI: 10.1002/jcp.20363] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Hepatitis C virus (HCV) is the major causative viral agent of cirrhosis and hepatocarcinoma (HCC). HCV core protein affects cell homeostasis, playing an important role in viral pathogenesis of HCC. We investigate the effects of HCV core protein expression on cell growth in HCC cell lines. Cell cycle distribution analysis of HepG2 polyclonal core positive cells reveals a peculiar accumulation of cells in G2/M phase. Different pathways mediate G2/M arrest: such as p53 and double strand RNA protein kinase (PKR). Flow cytometry in p53-null cells demonstrates that p53 plays only a marginal role in inducing HCV core-dependent G2/M phase accumulation that seems to be significantly affected by the functional inactivation of PKR. HCC core positive cells are characterized by a significant PKR phosphorylation in Thr 446 residue, which leads deregulation of mitosis. Moreover, we observe that the overexpression of the viral protein induces an upregulation of PKR activity, which does not correlate with an increased eIF-2 phosphorylation. This uncommon behavior of PKR suggests that its activation by HCV core protein could involve alternative PKR-dependent pathways, implicated in core-dependent G2/M accumulation. The described biological effects of HCV core protein on cell cycle could be an additional viral mechanism for both HCV resistance to interferon (IFN) and HCC HCV-related pathogenesis.
Collapse
Affiliation(s)
- A Alisi
- Dipartimento di Medicina Interna e Sanità Pubblica (M.I.S.P.), University of L'Aquila, L'Aquila, Italy
| | | | | | | | | | | |
Collapse
|
137
|
Morley SJ, Coldwell MJ, Clemens MJ. Initiation factor modifications in the preapoptotic phase. Cell Death Differ 2005; 12:571-84. [PMID: 15900314 DOI: 10.1038/sj.cdd.4401591] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Recent studies have identified several mechanistic links between the regulation of translation and the process of apoptosis. Rates of protein synthesis are controlled by a wide range of agents that induce cell death, and in many instances, the changes that occur to the translational machinery precede overt apoptosis and loss of cell viability. The two principal ways in which factors required for translational activity are modified prior to and during apoptosis involve (i) changes in protein phosphorylation and (ii) specific proteolytic cleavages. In this review, we summarise the principal targets for such regulation, with particular emphasis on polypeptide chain initiation factors eIF2 and eIF4G and the eIF4E-binding proteins. We indicate how the functions of these factors and of other proteins with which they interact may be altered as a result of activation of apoptosis and we discuss the potential significance of such changes for translational control and cell growth regulation.
Collapse
Affiliation(s)
- S J Morley
- Department of Biochemistry, School of Life Sciences, University of Sussex, Falmer, Brighton BN1 9QG, UK.
| | | | | |
Collapse
|
138
|
Lai FJ, Cheng CL, Chen ST, Wu CH, Hsu LJ, Lee JYY, Chao SC, Sheen MC, Shen CL, Chang NS, Sheu HM. WOX1 Is Essential for UVB Irradiation–Induced Apoptosis and Down-Regulated via Translational Blockade in UVB-Induced Cutaneous Squamous Cell Carcinoma In vivo. Clin Cancer Res 2005; 11:5769-77. [PMID: 16115915 DOI: 10.1158/1078-0432.ccr-04-2274] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
PURPOSE We investigated the role of candidate tumor suppressor and proapoptotic WOX1 (also named WWOX, FOR, or WWOXv1) in UVB-induced apoptosis and formation of cutaneous squamous cell carcinomas (SCC). EXPERIMENTAL DESIGN Expression of WOX1 and family proteins (WWOX) in human primary cutaneous SCCs was examined by immunohistochemistry, in situ hybridization, and reverse transcription-PCR. UVB irradiation-induced WOX1 activation (Tyr33 phosphorylation and nuclear translocation), apoptosis, and cutaneous SCC formation were examined both in vitro and in vivo. RESULTS Up-regulation of human WOX1, isoform WOX2, and Tyr33 phosphorylation occurred during normal keratinocyte differentiation before cornification and death. Interestingly, significant reduction of these proteins and Tyr33 phosphorylation was observed in nonmetastatic and metastatic cutaneous SCCs (P < 0.001), but without down-regulation of WWOX mRNA (P > 0.05 versus normal controls), indicating a translational blockade of WWOX mRNA to protein. During acute exposure of hairless mice to UVB, WOX1 was up-regulated and activated in epidermal cells in 24 hours. In parallel with the clinical findings in humans, chronic UVB-treated mice developed cutaneous SCCs in 3 months, with significant reduction of WOX1 and Tyr33 phosphorylation and, again, without down-regulation of WWOX mRNA. Human SCC-25 and HaCaT cells were transfected with small interfering RNA-targeting WOX1 and shown to resist UVB-induced WOX1 expression, activation, and apoptosis. CONCLUSIONS WOX1 is essential for UVB-induced apoptosis and likely to be involved in the terminal differentiation of normal keratinocytes. During UVB-induced cutaneous SCC, epidermal cells have apparently prevented the apoptotic pressure from overexpressed WOX1 by shutting down the translation machinery for WWOX mRNA.
Collapse
Affiliation(s)
- Feng-Jie Lai
- Department of Dermatology, National Cheng Kung University, Tainan, Taiwan.
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
139
|
Lynch M, Chen L, Ravitz MJ, Mehtani S, Korenblat K, Pazin MJ, Schmidt EV. hnRNP K binds a core polypyrimidine element in the eukaryotic translation initiation factor 4E (eIF4E) promoter, and its regulation of eIF4E contributes to neoplastic transformation. Mol Cell Biol 2005; 25:6436-53. [PMID: 16024782 PMCID: PMC1190351 DOI: 10.1128/mcb.25.15.6436-6453.2005] [Citation(s) in RCA: 96] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2004] [Revised: 12/23/2004] [Accepted: 05/02/2005] [Indexed: 11/20/2022] Open
Abstract
Translation initiation factor eukaryotic translation initiation factor 4E (eIF4E) plays a key role in regulation of cellular proliferation. Its effects on the m7GpppN mRNA cap are critical because overexpression of eIF4E transforms cells, and eIF4E function is rate-limiting for G1 passage. Although we identified eIF4E as a c-Myc target, little else is known about its transcriptional regulation. Previously, we described an element at position -25 (TTACCCCCCCTT) that was critical for eIF4E promoter function. Here we report that this sequence (named 4EBE, for eIF4E basal element) functions as a basal promoter element that binds hnRNP K. The 4EBE is sufficient to replace TATA sequences in a heterologous reporter construct. Interactions between 4EBE and upstream activator sites are position, distance, and sequence dependent. Using DNA affinity chromatography, we identified hnRNP K as a 4EBE-binding protein. Chromatin immunoprecipitation, siRNA interference, and hnRNP K overexpression demonstrate that hnRNP K can regulate eIF4E mRNA. Moreover, hnRNP K increased translation initiation, increased cell division, and promoted neoplastic transformation in an eIF4E-dependent manner. hnRNP K binds the TATA-binding protein, explaining how the 4EBE might replace TATA in the eIF4E promoter. hnRNP K is an unusually diverse regulator of multiple steps in growth regulation because it also directly regulates c-myc transcription, mRNA export, splicing, and translation initiation.
Collapse
Affiliation(s)
- Mary Lynch
- Cancer Research Center at Massachusetts General Hospital and Harvard Medical School, 55 Fruit St., Boston, MA 02114, USA
| | | | | | | | | | | | | |
Collapse
|
140
|
Zhang PL, Pellitteri PK, Law A, Gilroy PA, Wood GC, Kennedy TL, Blasick TM, Lun M, Schuerch C, Brown RE. Overexpression of phosphorylated nuclear factor-kappa B in tonsillar squamous cell carcinoma and high-grade dysplasia is associated with poor prognosis. Mod Pathol 2005; 18:924-32. [PMID: 15920558 DOI: 10.1038/modpathol.3800372] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Intracellular signals along the epidermal growth factor receptor (EGFR)-Akt-nuclear factor-kappa B (NF-kappaB) pathway have been associated with carcinogenesis in various malignant neoplasms. This investigation was to evaluate the expression of EGFR, phosphorylated(p)-Akt and p-NF-kappaB and correlate them with clinical outcomes in patients with squamous cell carcinoma of the tonsil. A total of 45 patients with squamous cell carcinoma of the tonsil were studied by immunohistochemistry to evaluate the expression levels of EGFR, p-Akt and p-NF-kappaB. Results for squamous cell carcinoma of the tonsil were compared with those for associated high-grade dysplasia and adjacent normal appearing epithelium, when present. In addition, tonsillar epithelium from non-neoplastic specimens of age-matched patients also was stained for the same markers. High-grade dysplasia and squamous cell carcinoma of the tonsil demonstrated a similar pattern of expression, which differed from the pattern seen in the adjacent normal epithelium and tonsillar epithelium from normal controls (an overexpression for each of these three protein analytes in high-grade dysplasia and squamous cell carcinoma of the tonsil as demonstrated by immunohistochemistry). When markers from squamous cell carcinoma of the tonsil were correlated with survival status, only increasing levels of p-NF-kappaB immunoreactivity (a relative overexpression) were statistically significant predictors of poor survival. No markers in squamous cell carcinoma of the tonsil were significantly related to rate of recurrence. When analyzing marker scores from tissue with high-grade dysplasia, relative overexpressions of both p-Akt and p-NF-kappaB were significantly related to poor survival. Additionally, increasing levels of p-NF-kappaB immunopositivity from tissue with high-grade dysplasia were also significantly related to rate of recurrence. In summary, p-NF-kappaB, overexpressed in high-grade dysplasia and squamous cell carcinoma of the tonsil, is associated with worse prognosis in terms of high recurrence and poor survival, respectively. This significant finding in patients with squamous cell carcinoma of the tonsil, in combination with previous animal and in vitro studies, suggests that p-NF-kappaB represents a potential therapeutic target in head and neck squamous cell carcinoma.
Collapse
Affiliation(s)
- Ping L Zhang
- Division of Laboratory Medicine, Geisinger Medical Center, Danville, PA 17822-0131, USA
| | | | | | | | | | | | | | | | | | | |
Collapse
|
141
|
Gorrini C, Loreni F, Gandin V, Sala LA, Sonenberg N, Marchisio PC, Biffo S. Fibronectin controls cap-dependent translation through beta1 integrin and eukaryotic initiation factors 4 and 2 coordinated pathways. Proc Natl Acad Sci U S A 2005; 102:9200-5. [PMID: 15961545 PMCID: PMC1166589 DOI: 10.1073/pnas.0409513102] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Fibronectin (FN) is a major matrix protein involved in multiple processes. Little is known about how adhesion to FN affects the translational machinery. We show that in fibroblasts adhesion to FN triggers translation through the coordinated regulation of eukaryotic initiation factors (eIFs) 4F and 2 and is impaired by blocking beta1 integrin engagement. FN-stimulated translation has unique properties: (i) it is highly sensitive to the inhibition of phosphatidylinositol 3-kinase (PI3K), but not to the inhibition of mammalian target of rapamycin, downstream of PI3K; (ii) there is no synergy between serum-stimulated translation and FN-dependent translation; (iii) FN-dependent translation, unlike growth factor-stimulated translation, does not lead to increased translocation of 5' terminal oligopyrimidine tract mRNAs to polysomes; and (iv) cells devoid of attachment to matrix show an impairment of initiation of translation accompanied by phosphorylation of eIF2alpha, which cannot be reverted by active PI3K. These findings indicate that integrins may recruit the translational machinery in a unique way and that FN-dependent translation cannot be blocked by mammalian target of rapamycin inhibition.
Collapse
Affiliation(s)
- Chiara Gorrini
- Molecular Histology Unit, San Raffaele Institute, 20132 Milan, Italy
| | | | | | | | | | | | | |
Collapse
|
142
|
Zhou C, Arslan F, Wee S, Krishnan S, Ivanov AR, Oliva A, Leatherwood J, Wolf DA. PCI proteins eIF3e and eIF3m define distinct translation initiation factor 3 complexes. BMC Biol 2005; 3:14. [PMID: 15904532 PMCID: PMC1173091 DOI: 10.1186/1741-7007-3-14] [Citation(s) in RCA: 109] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2005] [Accepted: 05/17/2005] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND PCI/MPN domain protein complexes comprise the 19S proteasome lid, the COP9 signalosome (CSN), and eukaryotic translation initiation factor 3 (eIF3). The eIF3 complex is thought to be composed of essential core subunits required for global protein synthesis and non-essential subunits that may modulate mRNA specificity. Interactions of unclear significance were reported between eIF3 subunits and PCI proteins contained in the CSN. RESULTS Here, we report the unexpected finding that fission yeast has two distinct eIF3 complexes sharing common core subunits, but distinguished by the PCI proteins eIF3e and the novel eIF3m, which was previously annotated as a putative CSN subunit. Whereas neither eIF3e nor eIF3m contribute to the non-essential activities of CSN in cullin-RING ubiquitin ligase control, eif3m, unlike eif3e, is an essential gene required for global cellular protein synthesis and polysome formation. Using a ribonomic approach, this phenotypic distinction was correlated with a different set of mRNAs associated with the eIF3e and eIF3m complexes. Whereas the eIF3m complex appears to associate with the bulk of cellular mRNAs, the eIF3e complex associates with a far more restricted set. The microarray findings were independently corroborated for a random set of 14 mRNAs by RT-PCR analysis. CONCLUSION We propose that the PCI proteins eIF3e and eIF3m define distinct eIF3 complexes that may assist in the translation of different sets of mRNAs.
Collapse
Affiliation(s)
- Chunshui Zhou
- Department of Genetics and Complex Diseases, Harvard School of Public Health, 665 Huntington Avenue, Boston, Massachusetts, 02115, USA
- Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Fatih Arslan
- Department of Genetics and Complex Diseases, Harvard School of Public Health, 665 Huntington Avenue, Boston, Massachusetts, 02115, USA
| | - Susan Wee
- Department of Genetics and Complex Diseases, Harvard School of Public Health, 665 Huntington Avenue, Boston, Massachusetts, 02115, USA
| | | | - Alexander R Ivanov
- Harvard NIEHS Center Proteomics Facility, Harvard School of Public Health, Boston, Massachusetts, USA
| | - Anna Oliva
- Department of Molecular Genetics and Microbiology, State University of New York, Stony Brook, New York, USA
| | - Janet Leatherwood
- Department of Molecular Genetics and Microbiology, State University of New York, Stony Brook, New York, USA
| | - Dieter A Wolf
- Department of Genetics and Complex Diseases, Harvard School of Public Health, 665 Huntington Avenue, Boston, Massachusetts, 02115, USA
- Harvard NIEHS Center Proteomics Facility, Harvard School of Public Health, Boston, Massachusetts, USA
| |
Collapse
|
143
|
Abstract
Cells respond to stress stimuli through coordinated changes in gene expression. The regulation of translation is often used under these circumstances because it allows immediate and selective changes in protein levels. There are many examples of translational control in response to stress. Here we examine two representative models, the regulation of eukaryotic initiation factor-2alpha by phosphorylation and internal ribosome initiation through the internal ribosome-entry site, which illustrate the importance of translational control in the cellular stress response and apoptosis.
Collapse
Affiliation(s)
- Martin Holcik
- Apoptosis Research Center, Room R3116, Children's Hospital of Eastern Ontario, 401 Smyth Road, Ottawa, ON, K1H 8L1, Canada.
| | | |
Collapse
|
144
|
Gupta AK, Rusterholz C, Holzgreve W, Hahn S. Constant IFNgamma mRNA to protein ratios in cord and adult blood T cells suggests regulation of IFNgamma expression in cord blood T cells occurs at the transcriptional level. Clin Exp Immunol 2005; 140:282-8. [PMID: 15807852 PMCID: PMC1809372 DOI: 10.1111/j.1365-2249.2005.02758.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Low levels of IFNgamma produced by umbilical cord blood (UCB) T lymphocytes upon activation may be due to the need for a high threshold of activation or to intrinsic blocking transcription/translation. We examined IFNgamma mRNA accumulation and protein expression in pharmacologically stimulated human UCB and adult blood (AB) T cells. Our data indicate that both IFNgamma mRNA accumulation and protein synthesis were significantly lower in stimulated UCB T cells than the AB T cells. Since the RNA dependent kinase PKR, an inhibitor of translation, can be activated by low levels of IFNgamma mRNA, we measured its involvement. Treatment with 2-amino-purine, an inhibitor of PKR, did not enhance IFNgamma protein expression in UCB T cells. Furthermore, our studies indicated that IFNgamma promoter hypermethylation does not appear to regulate IFNgamma expression either, as treatment with the demethylating agent, 5-aza-2'-deoxycytidine, did not lead to a significant increase in IFNgamma mRNA accumulation in UCB T cells. What is readily evident from our studies is that the IFNgamma mRNA to protein ratio was similar in UCB and AB T cells and it was not altered by any of the treatments used. These results therefore suggests that IFNgamma expression in UCB T cells is suppressed at the transcriptional level by an unknown mechanism(s).
Collapse
Affiliation(s)
- A Kumar Gupta
- Laboratory for Prenatal Medicine, University Women's Hospital/Department of Research, University of Basel, Spitalstrasse, 21 CH 4031 Basel, Switzerland
| | | | | | | |
Collapse
|
145
|
Hernández JM, Castilla C, Gutiérrez NC, Isidro IM, Delgado M, de las Rivas J, Fermiñán E, García JL, Ocio EM, del Cañizo MC, San Miguel JF. Mobilisation with G-CSF in healthy donors promotes a high but temporal deregulation of genes. Leukemia 2005; 19:1088-91. [PMID: 15830010 DOI: 10.1038/sj.leu.2403753] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
|
146
|
|
147
|
Jiang HY, Wek RC. Phosphorylation of the alpha-subunit of the eukaryotic initiation factor-2 (eIF2alpha) reduces protein synthesis and enhances apoptosis in response to proteasome inhibition. J Biol Chem 2005; 280:14189-202. [PMID: 15684420 DOI: 10.1074/jbc.m413660200] [Citation(s) in RCA: 236] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Protein ubiquitination and subsequent degradation by the proteasome are important mechanisms regulating cell cycle, growth and differentiation, and apoptosis. Recent studies in cancer therapy suggest that drugs that disrupt the ubiquitin/proteasome pathway induce apoptosis and sensitize malignant cells and tumors to conventional chemotherapy. In this study we addressed the role of phosphorylation of the alpha-subunit eukaryotic initiation factor-2 (eIF2), and its attendant regulation of gene expression, in the cellular stress response to proteasome inhibition. Phosphorylation of eIF2alpha in mouse embryo fibroblast (MEF) cells subjected to proteasome inhibition leads to a significant reduction in protein synthesis, concomitant with induced expression of the bZIP transcription regulator, ATF4, and its target gene CHOP/GADD153. The primary eIF2alpha kinase activated by exposure of these fibroblast cells to proteasome inhibition is GCN2 (EIF2AK4), which has a central role in the recognition of cytoplasmic stress signals. Endoplasmic reticulum (ER) stress is not effectively induced in MEF cells subjected to proteasome inhibition, with minimal activation of the ER stress sensory proteins, eIF2alpha kinase PEK (PERK/EIF2AK3), IRE1 protein kinase and the transcription regulator ATF6 following up to 6 h of proteasome inhibitor treatment. Loss of eIF2alpha phosphorylation thwarts caspase activation and delays apoptosis. Central to this pro-apoptotic function of eIF2alpha kinases during proteasome inhibition is the transcriptional regulator CHOP, as deletion of CHOP in MEF cells impedes apoptosis. We conclude that eIF2alpha kinases are integral to cellular stress pathways induced by proteasome inhibitors, and may be central to the efficacy of anticancer drugs that target the ubiquitin/proteasome pathway.
Collapse
Affiliation(s)
- Hao-Yuan Jiang
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana 46202, USA.
| | | |
Collapse
|
148
|
Abstract
The completion of a microarray experiment represents just a starting point toward understanding the biology of interest. A follow-up strategy is needed to fully elucidate the functional significance of microarray-derived measurements of differential expression. Given the fact that no single approach can fully unravel the fundamental biology that is typically quite complex, the follow-up strategy must be integrated at multiple levels encompassing bioinformatics, genomics, and proteomics. In this review, we discuss an integrative approach, which can be used to prioritize microarray-derived candidate genes, define their functions, and place them in the context of the biological system being studied.
Collapse
Affiliation(s)
- Xinmin Li
- Functional Genomics Facility, Division of Biological Sciences, The University of Chicago, 5841 S. Maryland Ave., Chicago, IL 60637, USA.
| | | |
Collapse
|
149
|
Abstract
Eukaryotic initiation factor eIF2 and its 'exchange factor' eIF2B play a key role in the regulation of protein synthesis in eukaryotes from yeast to mammals. Phosphorylation of eIF2 inhibits eIF2B and thus translation initiation. Four eIF2 kinases are now known in mammalian cells and these are activated in response to specific stress conditions. While phosphorylation of eIF2 serves to impair general protein synthesis, it causes upregulation of the translation of certain specific mRNAs that encode transcription factors. It can, therefore, exert effects on gene expression at multiple levels. The importance of correct control of eIF2 and eIF2B for normal physiology is exemplified by data from transgenic mice carrying knock-in or knock-out mutations and by the fact that mutations in the genes for the eIF2 kinase PERK or for eIF2B give rise to serious human diseases.
Collapse
Affiliation(s)
- Christopher G Proud
- Division of Molecular Physiology, School of Life Sciences, University of Dundee, Dunde DD15EH, United Kingdom.
| |
Collapse
|
150
|
Parsa AT, Holland EC. Cooperative translational control of gene expression by Ras and Akt in cancer. Trends Mol Med 2004; 10:607-13. [PMID: 15567331 DOI: 10.1016/j.molmed.2004.10.009] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Ras and Akt are signaling proteins that mediate fundamental aspects of normal growth and development in many organisms. When the Ras and Akt pathways become overly active, malignant transformation of normal tissue can occur. The combined activity of these two proteins has generated the transformation of human cell cultures and tumor formation in mice. In this review we highlight malignant glioma as a tumor type in which Ras and Akt pathways cooperate to cause tumorigenesis and regulate translation. The downstream components of these pathways have provided therapeutic targets that are currently being tested in clinical trials.
Collapse
Affiliation(s)
- Andrew T Parsa
- Department of Neurological Surgery, University of California San Francisco, CA 94143, USA
| | | |
Collapse
|