251
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Increased STAT-3 and synchronous activation of Raf-1-MEK-1-MAPK, and phosphatidylinositol 3-Kinase-Akt-mTOR pathways in atypical and anaplastic meningiomas. J Neurooncol 2008; 92:129-36. [PMID: 19034385 DOI: 10.1007/s11060-008-9746-7] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2008] [Accepted: 11/17/2008] [Indexed: 10/21/2022]
Abstract
The intracellular events promoting meningioma cell proliferation in high grade tumors are not established. In this study we compared 45 WHO grade I and 35 grade II or III meningiomas by Western blot or immunohistochemistry for phosphorylation/activation of the MEK-1-MAPK, PI3 K-Akt-mTOR-PRAS40 and STAT3 pathways. By Western blot, STAT3 activation was detected in 75% of grade I compared to 100% of grade II and III meningiomas. By immunohistochemistry p-STAT3 was detected in 28% of grade I compared to 65 or 66% of grade II and III meningiomas, respectively. Phosphorylated MEK-1 and p-MAPK were activated in nearly all grade I, II and III tumors. Phosphorylated Akt was also detected in the majority of meningiomas of each grade although downstream pathway component activation was less widespread. These findings suggest that there is increased STAT3 activation in WHO grade II and III meningiomas compared with grade I tumors. Moreover, each of the three major growth regulatory pathways is concomitantly activated in higher grade meningiomas.
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252
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Lahsnig C, Mikula M, Petz M, Zulehner G, Schneller D, van Zijl F, Huber H, Csiszar A, Beug H, Mikulits W. ILEI requires oncogenic Ras for the epithelial to mesenchymal transition of hepatocytes and liver carcinoma progression. Oncogene 2008; 28:638-50. [PMID: 19015638 DOI: 10.1038/onc.2008.418] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
In human hepatocellular carcinoma (HCC), epithelial to mesenchymal transition (EMT) correlates with aggressiveness of tumors and poor survival. We employed a model of EMT based on immortalized p19(ARF) null hepatocytes (MIM), which display tumor growth upon expression of oncogenic Ras and undergo EMT through the synergism of Ras and transforming growth factor (TGF)-beta. Here, we show that the interleukin-related protein interleukin-like EMT inducer (ILEI), a novel EMT-, tumor- and metastasis-inducing protein, cooperates with oncogenic Ras to cause TGF-beta-independent EMT. Ras-transformed MIM hepatocytes overexpressing ILEI showed cytoplasmic E-cadherin, loss of ZO-1 and induction of alpha-smooth muscle actin as well as platelet-derived growth factor (PDGF)/PDGF-R isoforms. As shown by dominant-negative PDGF-R expression in these cells, ILEI-induced PDGF signaling was required for enhanced cell migration, nuclear accumulation of beta-catenin, nuclear pY-Stat3 and accelerated growth of lung metastases. In MIM hepatocytes expressing the Ras mutant V12-C40, ILEI collaborated with PI3K signaling resulting in tumor formation without EMT. Clinically, human HCC samples showed granular or cytoplasmic localization of ILEI correlating with well and poorly differentiated tumors, respectively. In conclusion, these data indicate that ILEI requires cooperation with oncogenic Ras to govern hepatocellular EMT through mechanisms involving PDGF-R/beta-catenin and PDGF-R/Stat3 signaling.
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Affiliation(s)
- C Lahsnig
- Institute of Cancer Research, Department of Medicine I, Medical University of Vienna, Borschke-Gasse 8a, Vienna, Austria
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253
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Kumamoto T, Fujii M, Hou DX. Myricetin directly targets JAK1 to inhibit cell transformation. Cancer Lett 2008; 275:17-26. [PMID: 18995957 DOI: 10.1016/j.canlet.2008.09.027] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2008] [Revised: 09/02/2008] [Accepted: 09/30/2008] [Indexed: 11/17/2022]
Abstract
JAK1/STAT3 pathway has been suggested to play a role in cell transformation and carcinogenesis. In the present study, we found that myricetin (3, 3', 4', 5, 5', 7-hexahydroxyflavone), a typical flavonol existing in many fruits and vegetables, could directly bind to JAK1/STAT3 molecules to inhibit cell transformation in epidermal growth factor (EGF)-activated mouse JB6 P(+) cells. Colony assay revealed that myricetin had the strongest inhibitory effect on cell transformation among three flavonols including myricetin, quercetin and kaempferol. Molecular data revealed that myricetin inhibited DNA- binding and transcriptional activity of STAT3. Furthermore, myricetin inhibited the phosphorylation of STAT3 at Tyr705 and Ser727. Cellular signaling analyses revealed that EGF could induce the phosphorylation of Janus Kinase (JAK) 1, but not JAK2. Myricetin inhibited the phosphorylation of JAK1 and increased the autophosphorylation of EGF receptor (EGFR). Moreover, ex vivo and in vitro pull-down assay revealed that myricetin bound to JAK1 and STAT3, but not EGFR. Affinity data further demonstrated that myricetin had a higher affinity for JAK1 than STAT3. Thus, our data indicate that myricetin might directly target JAK1 to block cell transformation in mouse JB6 cells.
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Affiliation(s)
- Takuma Kumamoto
- Department of Biochemical Science and Technology, Faculty of Agriculture, Kagoshima University, Korimoto 1-21-24, Kagoshima City 890-0065, Japan
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254
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Abstract
There are four members of the EGFR family: EGFR, erbB2, erbB3 and erbB4. These receptors form ligand-activated oligomers which regulate intracellular processes via an oligomeric tyrosine kinase scaffold. The receptors are activated when the extracellular domain undergoes a conformational change which facilitates either homo- or hetero-oligomerization with other family members. The absence of one EGFR family member leads to embryonic or early post-natal death due to implantation, central nervous system or cardiac defects. Many mouse models of defective or deficient EGFR family members are available for studying physiology and/or pathology of EGFR family members. Sophisticated antibody and kinase inhibitors which target different family members have been designed, produced. EGFR and erbB2 are frequently activated, over expressed or mutated in many common cancers and the antagonists and/or inhibitors of EGFR and/or erbB2 signalling have already been shown to have therapeutic benefits for cancer patients.
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Affiliation(s)
- Antony W Burgess
- Ludwig Institute for cancer Research, Melbourne, Victoria, Australia.
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255
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Durmuş Tekir S, Yalçin Arga K, Ulgen KO. Drug targets for tumorigenesis: insights from structural analysis of EGFR signaling network. J Biomed Inform 2008; 42:228-36. [PMID: 18790083 DOI: 10.1016/j.jbi.2008.08.008] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2007] [Revised: 07/15/2008] [Accepted: 08/17/2008] [Indexed: 02/01/2023]
Abstract
Deciphering the complex network structure is crucial in drug target identification. This study presents a framework incorporating graph theoretic and network decomposition methods to analyze system-level properties of the comprehensive map of the epidermal growth factor receptor (EGFR) signaling, which is a good candidate model system to study the general mechanisms of signal transduction. The graph theoretic analysis of the EGFR network indicates that it has small-world characteristics with scale-free topology. The employment of network decomposition analysis enlightened the system-level properties, such as network cross-talk, specific molecules in each pathway and participation of molecules in the network. Participating in a significant fraction of the fundamental paths connecting the ligands to the phenotypes, cofactor GTP and complex Gbeta/Ggamma were identified as "housekeeping" molecules, through which all pathways of EGFR network are cross-talking. c-Src-Shc complex is identified as important due to its role in all fundamental paths through tumorigenesis and being specific to this phenotype. Inhibitors of this complex may be good anti-cancer agents having very little or no effect on other phenotypes.
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Affiliation(s)
- Saliha Durmuş Tekir
- Department of Chemical Engineering, Boğaziçi University, 34342 Bebek-Istanbul, Turkey.
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256
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Interleukin-3 promotes expansion of hemopoietic-derived CD45+ angiogenic cells and their arterial commitment via STAT5 activation. Blood 2008; 112:350-61. [DOI: 10.1182/blood-2007-12-128215] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Abstract
Interleukin-3 (IL-3) released by infiltrating inflammatory cells in different pathologic settings contributes to organ and tumor angiogenesis. Here we demonstrate that IL-3 expands a subset of CD45+ circulating angiogenic cells clonally derived from the hemopoietic progenitors. Moreover, CD45+ cells exposed to IL-3 acquire arterial specification and contribute to the formation of vessels in vivo. Depletion of signal transducer and activator of transcription 5 (STAT5) provides evidence that IL-3–mediated cell expansion and arterial morphogenesis rely on STAT5 activation. In addition, by means of Tie2-transgenic mice, we demonstrate that STAT5 also regulates IL-3–induced expansion and arterial specification of bonemarrow–derived CD45+ cells. Thus, our data provide the first evidence that, in inflammatory microenvironments containing IL-3, angiogenic cells derived from hemopoietic precursors can act as adult vasculogenic cells. Moreover, the characterization of the signaling pathway regulating these events provides the rationale for therapeutically targeting STAT5 in these pathologic settings.
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257
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Zhang M, Deng Y, Riedel H. PSM/SH2B1 splice variants: critical role in src catalytic activation and the resulting STAT3s-mediated mitogenic response. J Cell Biochem 2008; 104:105-18. [PMID: 18247337 DOI: 10.1002/jcb.21606] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
A role of PSM/SH2B1 had been shown in mitogenesis and extending to phenotypic cell transformation, however, the underlying molecular mechanism remained to be established. Here, four alternative PSM splice variants and individual functional protein domains were compared for their role in the regulation of Src activity. We found that elevated cellular levels of PSM variants resulted in phenotypic cell transformation and potentiated cell proliferation and survival in response to serum withdrawal. PSM variant activity presented a consistent signature pattern for any tested response of highest activity observed for gamma, followed by delta, alpha, and beta with decreasing activity. PSM-potentiated cell proliferation was sensitive to Src inhibitor herbimycin and PSM and Src were found in the same immune complex. PSM variants were substrates of the Src Tyr kinase and potentiated Src catalytic activity by increasing the V(max) and decreasing the K(m) for ATP with the signature pattern of variant activity. Dominant-negative PSM peptide mimetics including the SH2 or PH domains inhibited Src catalytic activity as well as Src-mediated phenotypic cell transformation. Activation of major Src substrate STAT3 was similarly potentiated by the PSM variants in a Src-dependent fashion or inhibited by PSM domain-specific peptide mimetics. Expression of a dominant-negative STAT3 mutant blocked PSM variant-mediated phenotypic cell transformation. Our results implicate an essential role of the PSM variants in the activation of the Src kinase and the resulting mitogenic response--extending to phenotypic cell transformation and involving the established Src substrate STAT3.
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Affiliation(s)
- Manchao Zhang
- Department of Biochemistry, West Virginia University, School of Medicine, Morgantown, West Virginia 26506-9142, USA
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258
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Pincheira R, Castro AF, Ozes ON, Idumalla PS, Donner DB. Type 1 TNF Receptor Forms a Complex with and Uses Jak2 and c-Src to Selectively Engage Signaling Pathways That Regulate Transcription Factor Activity. THE JOURNAL OF IMMUNOLOGY 2008; 181:1288-98. [DOI: 10.4049/jimmunol.181.2.1288] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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259
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Chien CM, Yang SH, Lin KL, Chen YL, Chang LS, Lin SR. Novel indoloquinoline derivative, IQDMA, suppresses STAT5 phosphorylation and induces apoptosis in HL-60 cells. Chem Biol Interact 2008; 176:40-7. [PMID: 18638462 DOI: 10.1016/j.cbi.2008.06.008] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2008] [Revised: 06/16/2008] [Accepted: 06/18/2008] [Indexed: 12/16/2022]
Abstract
Signal transducers and activators of transcription (STATs) are a family proteins that mediate cytokine and growth factor-induced signals playing a role in cell differentiation, proliferation, angiogenesis, and apoptosis. One STAT family member, STAT5, is often constitutively active in myeloid leukaemia. Agents that can suppress STAT5 activation have potential for prevention and treatment of cancer. N'-(11H-indolo[3,2-c]quinolin-6-yl)-N,N-dimethylethane-1,2-dia-mine (IQDMA), an indoloquinoline derivative, synthesized in our laboratory, has been demonstrated to be an effective anti-tumor agent in human leukemia cells. In the present report, we tested IQDMA for its ability to suppress STAT5 activation. We found that IQDMA inhibited constitutive activation of STAT5 in HL-60 cells in a dose- and time-dependent manner. The activation of Src and interleukin-6 (IL-6), implicated in STAT5 activation, was also inhibited by the IQDMA. Furthermore, IQDMA up-regulated Bax, and down-regulated Bcl-2, Bcl-X(L), cyclin D1, and vascular endothelial growth factor (VEGF) as followed by growth arrest of HL-60 cells, but the expression of survivin did not change in the presence of IQDMA. Taken together, these results indicate that IQDMA causes significant induction of apoptosis in HL-60 cells via down-regulation of Src, IL-6, and STAT5 signaling and modulation of Bcl-2 family, cyclin D1 and VEGF proteins. Thus, IQDMA appears to be a potential therapeutic agent for treating leukaemia HL-60 cells.
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Affiliation(s)
- Ching-Ming Chien
- Faculty of Medicinal and Applied Chemistry, Kaohsiung Medical University, Kaohsiung 807, Taiwan, ROC
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260
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Tan SH, Nevalainen MT. Signal transducer and activator of transcription 5A/B in prostate and breast cancers. Endocr Relat Cancer 2008; 15:367-90. [PMID: 18508994 PMCID: PMC6036917 DOI: 10.1677/erc-08-0013] [Citation(s) in RCA: 82] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Protein kinase signaling pathways, such as Janus kinase 2-Signal transducer and activator of transcription 5A/B (JAK2-STAT5A/B), are of significant interest in the search for new therapeutic strategies in both breast and prostate cancers. In prostate cancer, the components of the JAK2-STAT5A/B signaling pathway provide molecular targets for small-molecule inhibition of survival and growth signals of the cells. At the same time, new evidence suggests that the STAT5A/B signaling pathway is involved in the transition of organ-confined prostate cancer to hormone-refractory disease. This implies that the active JAK2-STAT5A/B signaling pathway potentially provides the means for pharmacological intervention of clinical prostate cancer progression. In addition, active STAT5A/B may serve as a prognostic marker for identification of those primary prostate cancers that are likely to progress to aggressive disease. In breast cancer, the role of STAT5A/B is more complex. STAT5A/B may have a dual role in the regulation of malignant mammary epithelium. Data accumulated from mouse models of breast cancer suggest that in early stages of breast cancer STAT5A/B may promote malignant transformation and enhance growth of the tumor. This is in contrast to established breast cancer, where STAT5A/B may mediate the critical cues for maintaining the differentiation of mammary epithelium. In addition, present data suggest that activation of STAT5A/B in breast cancer predicts favorable clinical outcome. The dual nature of STAT5A/B action in breast cancer makes the therapeutic use of STAT5 A/B more complex.
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Affiliation(s)
- Shyh-Han Tan
- Department of Cancer Biology, Kimmel Cancer Center, Thomas Jefferson University, 233 South 10th Street, BLSB 309, Philadelphia, Pennsylvania 19107, USA
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261
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Basham B, Sathe M, Grein J, McClanahan T, D'Andrea A, Lees E, Rascle A. In vivo identification of novel STAT5 target genes. Nucleic Acids Res 2008; 36:3802-18. [PMID: 18492722 PMCID: PMC2441806 DOI: 10.1093/nar/gkn271] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
STAT5A and STAT5B proteins belong to the family of signal transducers and activators of transcription. They are encoded by two separate genes with 91% identity in their amino acid sequences. Despite their high degree of conservation, STAT5A and STAT5B exert non-redundant functions, resulting at least in part from differences in target gene activation. To better characterize the differential contribution of STAT5A and STAT5B in gene regulation, we performed single or double knockdown of STAT5A and STAT5B using small interfering RNA. Subsequent gene expression profiling and RT-qPCR analyses of IL-3-stimulated Ba/F3-β cells led to the identification of putative novel STAT5 target genes. Chromatin immunoprecipitation assays analyzing the corresponding gene loci identified unusual STAT5 binding sites compared to conventional STAT5 responsive elements. Some of the STAT5 targets identified are upregulated in several human cancers, suggesting that they might represent potential oncogenes in STAT5-associated malignancies.
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Affiliation(s)
- Beth Basham
- Schering-Plough Biopharma, 901 California Avenue, Palo Alto, CA 94304, USA
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262
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263
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Abram CL, Lowell CA. The diverse functions of Src family kinases in macrophages. FRONT BIOSCI-LANDMRK 2008; 13:4426-50. [PMID: 18508521 DOI: 10.2741/3015] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Macrophages are key components of the innate immune response. These cells possess a diverse repertoire of receptors that allow them to respond to a host of external stimuli including cytokines, chemokines, and pathogen-associated molecules. Signals resulting from these stimuli activate a number of macrophage functional responses such as adhesion, migration, phagocytosis, proliferation, survival, cytokine release and production of reactive oxygen and nitrogen species. The cytoplasmic tyrosine kinase Src and its family members (SFKs) have been implicated in many intracellular signaling pathways in macrophages, initiated by a diverse set of receptors ranging from integrins to Toll-like receptors. However, it has been difficult to implicate any given member of the family in any specific pathway. SFKs appear to have overlapping and complementary functions in many pathways. Perhaps the function of these enzymes is to modulate the overall intracellular signaling network in macrophages, rather than operating as exclusive signaling switches for defined pathways. In general, SFKs may function more like rheostats, influencing the amplitude of many pathways.
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Affiliation(s)
- Clare L Abram
- Department of Laboratory Medicine, University of California, San Francisco, CA 94143, USA
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264
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An essential role for SRC-activated STAT-3 in 14,15-EET-induced VEGF expression and angiogenesis. Blood 2008; 111:5581-91. [PMID: 18408167 DOI: 10.1182/blood-2007-11-126680] [Citation(s) in RCA: 104] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
To understand the molecular mechanisms underlying 14,15-epoxyeicosatrienoic acid (14,15-EET)-induced angiogenesis, here we have studied the role of signal transducer and activator of transcription-3 (STAT-3). 14,15-EET stimulated the tyrosine phosphorylation of STAT-3 and its translocation from the cytoplasm to the nucleus in human dermal microvascular endothelial cells (HDMVECs). Adenovirus-mediated delivery of dominant negative STAT-3 substantially inhibited 14,15-EET-induced HDMVEC migration, and tube formation and Matrigel plug angiogenesis. 14,15-EET activated Src, as measured by its tyrosine phosphorylation and blockade of its activation by adenovirus-mediated expression of its dominant negative mutant, significantly attenuated 14,15-EET-induced STAT-3 phosphorylation in HDMVECs and the migration and tube formation of these cells and Matrigel plug angiogenesis. 14,15-EET induced the expression of vascular endothelial cell growth factor (VEGF) in a time- and Src-STAT-3-dependent manner in HDMVECs. Transfac analysis of VEGF promoter revealed the presence of STAT-binding elements and 14,15-EET induced STAT-3 binding to this promoter in vivo, and this interaction was inhibited by suppression of Src-STAT-3 signaling. Neutralizing anti-VEGF antibodies completely blocked 14,15-EET-induced HDMVEC migration and tube formation and Matrigel plug angiogenesis. These results reveal that Src-dependent STAT-3-mediated VEGF expression is a major mechanism of 14,15-EET-induced angiogenesis.
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265
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Rieger-Christ KM, Hanley R, Lodowsky C, Bernier T, Vemulapalli P, Roth M, Kim J, Yee AS, Le SM, Marie PJ, Libertino JA, Summerhayes IC. The green tea compound, (-)-epigallocatechin-3-gallate downregulates N-cadherin and suppresses migration of bladder carcinoma cells. J Cell Biochem 2008; 102:377-88. [PMID: 17348027 DOI: 10.1002/jcb.21299] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Green tea has been reported as potential dietary protection against numerous cancers and has been shown to have activity in bladder tumor inhibition in different animal models. The goal of this study was to examine the effects of (-)-epigallocatechin gallate (EGCG-the major phytochemical in green tea) on growth inhibition and behavior of human bladder carcinoma cells and to identify the altered signaling pathway(s) underlying the response to EGCG exposure. EGCG inhibited the in vitro growth of invasive bladder carcinoma cells with an IC(50) range of 70-87 microM. At a concentration of 20 microM, EGCG decreased the migratory potential of bladder carcinoma cells with concomitant activation of p42/44 MAPK and STAT3 and inactivation of Akt. Using biochemical inhibitors of MAPK/ERK, and siRNA to knockdown STAT3 and Akt, inhibition of migration was recorded associated with Akt but not MAPK/ERK or STAT3 signaling in bladder cells. In addition, EGCG downregulated N-cadherin in a dose-dependent manner where reduction in N-cadherin expression paralleled declining migratory potential. Continuous feeding of EGCG to mice prior to and during the establishment of bladder carcinoma xenografts in vivo revealed >50% reduction in mean final tumor volume (P </= 0.05) with no detectable toxicity. EGCG inhibited bladder carcinoma cell growth and suppressed the in vitro migration capacity of cells via downregulation of N-cadherin and inactivation of Akt signaling. Continuous administration of EGCG to mice revealed significant inhibition of tumor growth in vivo indicating a possible preventative role for green tea in bladder cancer.
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Affiliation(s)
- Kimberly M Rieger-Christ
- Cell and Molecular Biology Laboratory, Robert E. Wise Research and Education Institute, Lahey Clinic Medical Center, 31 Mall Road, Burlington, Massachusetts 01805, USA
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266
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Abstract
The epidermal growth factor receptor (EGFR) and signal transducers and activators of transcription (STATs) are commonly expressed and activated in many malignancies. EGFR is an upstream activator of several pathways involved in tumor progression, and STATs activate selected genes involved in oncogenesis. There are several different mechanisms by which STAT proteins can mediate intracellular EGFR signaling, including direct activation of STATs by EGFR binding and indirect activation of STATs through Src-mediated EGFR signaling. EGFR likely activates STAT in a manner distinctive from other mechanisms of STAT activation; STAT5 can be phosphorylated in an EGF-dependent manner at unique sites, conferring novel functions. Cumulative evidence suggests that targeting EGFR signaling pathways at several levels may demonstrate synergistic therapeutic effects compared with targeting the upstream receptor alone. Thus, methods to inhibit EGFR in conjunction with oncogenic STATs may represent a novel therapeutic strategy for cancers characterized by upregulation of EGFR signaling.
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Affiliation(s)
- Kelly M Quesnelle
- Department of Otolaryngology, University of Pittsburgh Cancer Institute, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15213, USA
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267
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Weaver AM, Silva CM. Signal transducer and activator of transcription 5b: a new target of breast tumor kinase/protein tyrosine kinase 6. Breast Cancer Res 2008; 9:R79. [PMID: 17997837 PMCID: PMC2246177 DOI: 10.1186/bcr1794] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2007] [Revised: 09/21/2007] [Accepted: 11/12/2007] [Indexed: 12/21/2022] Open
Abstract
Introduction Signal transducers and activators of transcription (STATs) are mediators of cytokine and growth factor signaling. In recent years, STAT5b has emerged as a key regulator of tumorigenesis. STAT5b phosphorylation and activation is mediated by several kinases known to be overexpressed in breast cancer, such as epidermal growth factor receptor, HER2, and c-Src. Breast tumor kinase (Brk), also known as protein tyrosine kinase 6, is a nonreceptor tyrosine kinase expressed in more than 60% of breast cancers. Only a few substrates of the Brk tyrosine kinase have been identified, the most recent being STAT3. In the present article we investigate the potential role of Brk in the phosphorylation and activation STAT5b. Methods To determine whether Brk can phosphorylate STAT5b, transient transfection and in vitro kinase assays were performed. Luciferase reporter assays were used to measure Brk-induced STAT5b transcriptional activity. siRNA technology was utilized to investigate the biological significance of Brk-induced activation of STAT5b in breast cancer cell models. Results Phosphospecific antibodies, mutational analysis, and in vitro kinase assays demonstrated that Brk specifically mediated STAT5b phosphorylation at the activating tyrosine, Y699. Transient transfection of Brk into the Brk-negative BT-549 breast cancer cell line enhanced STAT5b transcriptional activity, as measured by a STAT5-specific luciferase reporter. Furthermore, overexpression of kinase active c-Src enhanced Brk-induced STAT5b transcriptional activity. In Brk-positive breast cancer cell lines BT-20 and SKBr3, knockdown of Brk protein or of STAT5b protein using siRNA methodology resulted in a decrease in DNA synthesis. Knockdown of Brk and STAT5b together did not further decrease DNA synthesis compared with each alone, suggesting that Brk and STAT5b converge on the same pathway, ultimately leading to cellular proliferation. Conclusion Our studies demonstrate that Brk phosphorylates STAT5b on Y699, leading to increased STAT5b transcriptional activity. Furthermore, analysis of DNA synthesis suggests that STAT5b and Brk are converging upon the same proproliferative signaling pathway in breast cancer cells. We propose that Brk, like other tyrosine kinases, signals downstream to STAT5b to mediate proliferation of breast cancer cells. These results further establish STAT5b as well as Brk as potential targets for breast cancer therapy.
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Affiliation(s)
- Amanda M Weaver
- Department of Microbiology, University of Virginia, Charlottesville, VA 22908, USA
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268
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Porat-Shliom N, Kloog Y, Donaldson JG. A unique platform for H-Ras signaling involving clathrin-independent endocytosis. Mol Biol Cell 2008; 19:765-75. [PMID: 18094044 PMCID: PMC2262976 DOI: 10.1091/mbc.e07-08-0841] [Citation(s) in RCA: 108] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2007] [Revised: 11/05/2007] [Accepted: 12/07/2007] [Indexed: 11/11/2022] Open
Abstract
Trafficking of H-Ras was examined to determine whether it can enter cells through clathrin-independent endocytosis (CIE). H-Ras colocalized with the CIE cargo protein, class I major histocompatibility complex, and it was sequestered in vacuoles that formed upon expression of an active mutant of Arf6, Q67L. Activation of Ras, either through epidermal growth factor stimulation or the expression of an active mutant of Ras, G12V, induced plasma membrane ruffling and macropinocytosis, a stimulated form of CIE. Live imaging of cells expressing H-RasG12V and fluorescent protein chimeras with pleckstrin homology domains that recognize specific phosphoinositides showed that incoming macropinosomes contained phosphatidylinositol 4,5-bisphosphate (PIP(2)) and phosphatiylinositol 3,4,5-trisphosphate (PIP(3)). PIP(2) loss from the macropinosome was followed by the recruitment of Rab5, a downstream target of Ras, and then PIP(3) loss. Our studies support a model whereby Ras can signal on macropinosomes that pass through three distinct stages: PIP(2)/PIP(3), PIP(3)/Rab5, and Rab5. Vacuoles that form in cells expressing Arf6Q67L trap Ras signaling in the first stage, recruiting the active form of the Ras effectors extracellular signal-regulated kinase and protein kinase B (Akt) but not Rab5. Arf6 stimulation of macropinocytosis also involves passage through the distinct lipid phases, but recruitment of Akt is not observed.
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Affiliation(s)
- Natalie Porat-Shliom
- *Laboratory of Cell Biology, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892; and
- Department of Neurobiochemistry, Tel Aviv University, Tel Aviv, Israel
| | - Yoel Kloog
- Department of Neurobiochemistry, Tel Aviv University, Tel Aviv, Israel
| | - Julie G. Donaldson
- *Laboratory of Cell Biology, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892; and
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269
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Landen CN, Birrer MJ, Sood AK. Early Events in the Pathogenesis of Epithelial Ovarian Cancer. J Clin Oncol 2008; 26:995-1005. [DOI: 10.1200/jco.2006.07.9970] [Citation(s) in RCA: 319] [Impact Index Per Article: 19.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Ovarian carcinogenesis, as in most cancers, involves multiple genetic alterations. A great deal has been learned about proteins and pathways important in the early stages of malignant transformation and metastasis, as derived from studies of individual tumors, microarray data, animal models, and inherited disorders that confer susceptibility. However, a full understanding of the earliest recognizable events in epithelial ovarian carcinogenesis is limited by the lack of a well-defined premalignant state common to all ovarian subtypes and by the paucity of data from early-stage cancers. Evidence suggests that ovarian cancers can progress both through a stepwise mutation process (low-grade pathway) and through greater genetic instability that leads to rapid metastasis without an identifiable precursor lesion (high-grade pathway). In this review, we discuss many of the genetic and molecular disorders in each key process that is altered in cancer cells, and we present a model of ovarian pathogenesis that incorporates the role of tumor cell mutations and factors in the host microenvironment important to tumor initiation and progression.
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Affiliation(s)
- Charles N. Landen
- From the Department of Gynecologic Oncology and the Department of Cancer Biology, University of Texas M.D. Anderson Cancer Center, Houston, TX; and the Center for Cancer Research, National Cancer Institute, Bethesda, MD
| | - Michael J. Birrer
- From the Department of Gynecologic Oncology and the Department of Cancer Biology, University of Texas M.D. Anderson Cancer Center, Houston, TX; and the Center for Cancer Research, National Cancer Institute, Bethesda, MD
| | - Anil K. Sood
- From the Department of Gynecologic Oncology and the Department of Cancer Biology, University of Texas M.D. Anderson Cancer Center, Houston, TX; and the Center for Cancer Research, National Cancer Institute, Bethesda, MD
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270
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Sallman DA, Chen X, Zhong B, Gilvary DL, Zhou J, Wei S, Djeu JY. Clusterin mediates TRAIL resistance in prostate tumor cells. Mol Cancer Ther 2008; 6:2938-47. [PMID: 18025278 DOI: 10.1158/1535-7163.mct-07-0345] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
One of the major obstacles in curing prostate cancer is the development of drug resistance to docetaxel, which is the gold standard for the treatment of this disease. It is not only imperative to discover the molecular basis of resistance but also to find therapeutic agents that can disrupt the resistant pathways. Based on initial findings that docetaxel-resistant PC3-DR and DU145-DR prostate tumor cell lines express tumor necrosis factor-related apoptosis inducing ligand (TRAIL) receptors, we examined whether TRAIL could be used as an alternative method to kill PC3-DR and DU145-DR cells. However, these tumor cells were found to be TRAIL resistant. Because PC3-DR and DU-145-DR cells were previously shown by us to be clusterin positive, we examined if clusterin could play a role in TRAIL resistance. We found that resveratrol could sensitize docetaxel-resistant tumor cells to TRAIL, and it worked by blocking clusterin expression. In particular, small interfering RNA clusterin expression in the cell lines was sufficient to produce apoptosis by TRAIL. Further analysis indicated that resveratrol functions as an effective tyrosine kinase inhibitor, similar to its analogue, piceatannol, and could inhibit Src and Jak kinases, thus resulting in loss of Stat1 activation. We have shown earlier that Stat1 is essential for gene transcription of clusterin. These results, taken together, show that resveratrol could be a useful new therapeutic agent to combat docetaxel resistance.
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Affiliation(s)
- David A Sallman
- Immunology Program, H. Lee Moffitt Cancer Center, Department of Interdisciplinary, Oncology, University of South Florida College of Medicine, Tampa, FL, USA
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271
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Shimada N, Kanno-Tanabe N, Minemura K, Kawata T. GBF-dependent family genes morphologically suppress the partially active Dictyostelium STATa strain. Dev Genes Evol 2008; 218:55-68. [PMID: 18204858 DOI: 10.1007/s00427-008-0202-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2007] [Accepted: 01/01/2008] [Indexed: 02/01/2023]
Abstract
Transcription factor Dd-STATa, a functional Dictyostelium homologue of metazoan signal transducers and activators of transcription proteins, is necessary for culmination during development. We have isolated more than 18 putative multicopy suppressors of Dd-STATa using genetic screening. One was hssA gene, whose expression is known to be G-box-binding-factor-dependent and which was specific to prestalk A (pstA) cells, where Dd-STATa is activated. Also, hssA mRNA was expressed in pstA cells in the Dd-STATa-null mutant. At least 40 hssA-related genes are present in the genome and constitute a multigene family. The tagged HssA protein was translated; hssA encodes an unusually high-glycine-serine-rich small protein (8.37 kDa), which has strong homology to previously reported cyclic-adenosine-monophosphate-inducible 2C and 7E proteins. Overexpression of hssA mRNA as well as frame-shifted versions of hssA RNA suppressed the phenotype of the partially active Dd-STATa strain, suggesting that translation is not necessary for suppression. Although overexpression of prespore-specific genes among the family did not suppress the parental phenotype, prestalk-specific family members did. Although overexpression of the hssA did not revert the expression of Dd-STATa target genes, and although its suppression mechanism remains unknown, morphological reversion implies functional relationships between Dd-STATa and hssA.
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Affiliation(s)
- Nao Shimada
- Department of Biology, Faculty of Science, Toho University, 2-2-1 Miyama, Funabashi, Chiba, 274-8510, Japan
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272
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Transcription Factors STAT5 and STAT3. Prostate Cancer 2008. [DOI: 10.1007/978-1-60327-079-3_12] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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273
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Xu H, Washington S, Verderame MF, Manni A. Role of non-receptor and receptor tyrosine kinases (TKs) in the antitumor action of alpha-difluoromethylornithine (DFMO) in breast cancer cells. Breast Cancer Res Treat 2007; 112:255-61. [PMID: 18097746 DOI: 10.1007/s10549-007-9866-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2007] [Accepted: 12/10/2007] [Indexed: 10/22/2022]
Abstract
We have shown that administration of alpha-difluoromethylornithine (DFMO), an irreversible inhibitor of ornithine decarboxylase (ODC), the first and rate-limiting enzyme in polyamine (PA) biosynthesis, reduces the invasive and metastatic properties of MDA-MB-435 breast cancer cells while activating multiple signal transduction pathways, including MAPK, Stat3, Stat1, and JNK. Since the activity of these signaling mechanisms is frequently regulated by upstream tyrosine kinases (TKs), we tested whether non-receptor and receptor TKs may be involved in the signaling and biological effects of DFMO in MDA-MB-435 cells. Treatment with DFMO (1 mM for 48 h) did not affect Src phosphorylation (Tyr 416). Administration of the Src-family members inhibitor PP-1 (1 microM), blocked Src phosphorylation in the absence and in the presence of DFMO, but did not block the signaling effects of DFMO (increased phosphorylation of Stat3, Stat1, ERK and JNK). PP-1 treatment, on the other hand, inhibited the invasiveness of MDA-MB-435 cells in matrigel and potentiated the anti-invasive effect of DFMO. Next, we focused on the role of receptor TK. Western analysis of cell lysates from MDA-MB-435 cells failed to show the presence of EGF-R and HER-2neu but demonstrated the expression of c-Met, the receptor for hepatocyte growth factor (HGF). Therefore, we tested the effect of DFMO on the HGF/c-Met pathway which is strongly implicated in the progression of human breast cancer. We found that DFMO treatment blocked HGF-induced c-Met phosphorylation in MDA-MB-435 cells, suggesting that its anti-invasion action may be mediated, at least in part, by blocking c-Met signaling. Next, we showed that 1 mM DFMO suppressed HGF induced invasiveness of MDA-MB-435 cells in matrigel. Combination administration of DFMO with suboptimal doses of PHA-665752, a specific c-Met inhibitor, reduced invasiveness to an even greater extent than the individual treatment. These findings indicate that Src-family members, while not involved in DFMO action, promote invasiveness of breast cancer cells and their inhibition may enhance the antitumor effect of PA depletion. Our data also point to inhibition of HGF/c-Met pathway as a possible novel approach to enhancing the antitumor action of DFMO.
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Affiliation(s)
- Haifang Xu
- Department of Medicine, The Pennsylvania State University College of Medicine, Hershey, PA 17033, USA
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274
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Han LY, Landen CN, Trevino JG, Halder J, Lin YG, Kamat AA, Kim TJ, Merritt WM, Coleman RL, Gershenson DM, Shakespeare WC, Wang Y, Sundaramoorth R, Metcalf CA, Dalgarno DC, Sawyer TK, Gallick GE, Sood AK. Antiangiogenic and antitumor effects of SRC inhibition in ovarian carcinoma. Cancer Res 2007; 66:8633-9. [PMID: 16951177 PMCID: PMC3202609 DOI: 10.1158/0008-5472.can-06-1410] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Src, a nonreceptor tyrosine kinase, is a key mediator for multiple signaling pathways that regulate critical cellular functions and is often aberrantly activated in a number of solid tumors, including ovarian carcinoma. The purpose of this study was to determine the role of activated Src inhibition on tumor growth in an orthotopic murine model of ovarian carcinoma. In vitro studies on HeyA8 and SKOV3ip1 cell lines revealed that Src inhibition by the Src-selective inhibitor, AP23846, occurred within 1 hour and responded in a dose-dependent manner. Furthermore, Src inhibition enhanced the cytotoxicity of docetaxel in both chemosensitive and chemoresistant ovarian cancer cell lines, HeyA8 and HeyA8-MDR, respectively. In vivo, Src inhibition by AP23994, an orally bioavailable analogue of AP23846, significantly decreased tumor burden in HeyA8 (P = 0.02), SKOV3ip1 (P = 0.01), as well as HeyA8-MDR (P < 0.03) relative to the untreated controls. However, the greatest effect on tumor reduction was observed in combination therapy with docetaxel (P < 0.001, P = 0.002, and P = 0.01, for the above models, respectively). Proliferating cell nuclear antigen staining showed that Src inhibition alone (P = 0.02) and in combination with docetaxel (P = 0.007) significantly reduced tumor proliferation. In addition, Src inhibition alone and in combination with docetaxel significantly down-regulated tumoral production of vascular endothelial growth factor and interleukin 8, whereas combination therapy decreased the microvessel density (P = 0.02) and significantly affected vascular permeability (P < 0.05). In summary, Src inhibition with AP23994 has potent antiangiogenic effects and significantly reduces tumor burden in preclinical ovarian cancer models. Thus, Src inhibition may be an attractive therapeutic approach for patients with ovarian carcinoma.
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Affiliation(s)
- Liz Y. Han
- Department of Gynecologic Oncology University of Texas M.D. Anderson Cancer Center, Houston, Texas
| | - Charles N. Landen
- Department of Gynecologic Oncology University of Texas M.D. Anderson Cancer Center, Houston, Texas
| | - Jose G. Trevino
- Department of Cancer Biology, University of Texas M.D. Anderson Cancer Center, Houston, Texas
| | - Jyotsnabaran Halder
- Department of Gynecologic Oncology University of Texas M.D. Anderson Cancer Center, Houston, Texas
| | - Yvonne G. Lin
- Department of Gynecologic Oncology University of Texas M.D. Anderson Cancer Center, Houston, Texas
| | - Aparna A. Kamat
- Department of Gynecologic Oncology University of Texas M.D. Anderson Cancer Center, Houston, Texas
| | - Tae-Jin Kim
- Department of Gynecologic Oncology University of Texas M.D. Anderson Cancer Center, Houston, Texas
- Department of Gynecologic Oncology at Cheil General Hospital, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - William M. Merritt
- Department of Gynecologic Oncology University of Texas M.D. Anderson Cancer Center, Houston, Texas
| | - Robert L. Coleman
- Department of Gynecologic Oncology University of Texas M.D. Anderson Cancer Center, Houston, Texas
| | - David M. Gershenson
- Department of Gynecologic Oncology University of Texas M.D. Anderson Cancer Center, Houston, Texas
| | | | - Yihan Wang
- ARIAD Pharmaceuticals, Cambridge, Massachusetts
| | | | | | | | | | - Gary E. Gallick
- Department of Cancer Biology, University of Texas M.D. Anderson Cancer Center, Houston, Texas
| | - Anil K. Sood
- Department of Gynecologic Oncology University of Texas M.D. Anderson Cancer Center, Houston, Texas
- Department of Cancer Biology, University of Texas M.D. Anderson Cancer Center, Houston, Texas
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275
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Poincloux R, Cougoule C, Daubon T, Maridonneau-Parini I, Le Cabec V. Tyrosine-phosphorylated STAT5 accumulates on podosomes in Hck-transformed fibroblasts and chronic myeloid leukemia cells. J Cell Physiol 2007; 213:212-20. [PMID: 17503465 DOI: 10.1002/jcp.21112] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
In chronic myeloid leukemia (CML), the transforming activity of Bcr/Abl involves constitutive activation of the phagocyte specific Src-family tyrosine kinase Hck, which in turn directly activates the signal transducer and activator of transcription 5 (STAT5). The effect of Hck on STAT5 was first explored independently of Bcr/Abl by expressing the constitutively active Hck mutant (Hck(ca)) in MEF3T3-TetOff fibroblasts. As previously reported, Hck(ca)-expressing cells form podosomes which are actin-rich structures involved in trans-tissular cell migration and found in the few cell types able to cross anatomic boundaries. We demonstrated that in these cells, the tyrosine-phosphorylated form of STAT5 (PY-STAT5) increased and preferentially localized on podosomes together with Hck, instead of translocating to the nucleus as observed with conventional stimuli such as IFNgamma. To examine whether similar results were obtained in the presence of Bcr/Abl, the CML cell line K562 was used. We observed that (i) podosomal structures are present in these cells in contrast to Bcr/Abl-negative leukemic cells, (ii) podosome formation was inhibited by Bcr/Abl- and Src-kinase inhibitors, and (iii) PY-STAT5 mainly colocalized with Hck on these structures. The presence of podosomes was not sufficient to trap STAT5 since in normal macrophages which spontaneously form podosomes and express regulated Hck, PY-STAT5 is in the nucleus. In conclusion, this is the first report showing that PY-STAT5 associates to podosomes in a process dependent on constitutive activation of Hck. We propose that STAT5, previously classified as a transcription factor, could play another role outside the nucleus, elicited by the Bcr/Abl-Hck transforming pathway.
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Affiliation(s)
- Renaud Poincloux
- Institut de Pharmacologie et de Biologie Structurale, CNRS UMR 5089, Université Paul Sabatier Toulouse III, Route de Narbonne, Toulouse, France
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276
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Kusaba M, Nakao K, Goto T, Nishimura D, Kawashimo H, Shibata H, Motoyoshi Y, Taura N, Ichikawa T, Hamasaki K, Eguchi K. Abrogation of constitutive STAT3 activity sensitizes human hepatoma cells to TRAIL-mediated apoptosis. J Hepatol 2007; 47:546-55. [PMID: 17602782 DOI: 10.1016/j.jhep.2007.04.017] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/01/2006] [Revised: 04/24/2007] [Accepted: 04/26/2007] [Indexed: 12/04/2022]
Abstract
BACKGROUND/AIMS Signal transducer and activator of transcription 3 (STAT3) is constitutively activated and regulates cell growth and survival of various cancer cells. We investigated the anti-tumor effect of AG490, a Janus kinase 2 specific inhibitor, inhuman hepatoma cells. METHODS Effects of AG490 on STAT3 activation, on cell-growth and survival, and on the expression of cell-cycle- and apoptosis-related proteins were evaluated in Huh-1, Huh-7, HepG2 and Hep3B cells. Next, whether AG490 renders hepatoma cells susceptible to tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) was examined in vitro and in vivo. RESULTS Constitutively activated STAT3 through tyrosine phosphorylation was detected in all hepatoma cells. AG490 inhibited the phosphorylation of STAT3 and its activity. AG490 induced cell cycle arrest in Huh-1, Huh-7 and HepG2 through cyclin D1 downregulation, and induced marked apoptosis in Hep3B. AG490 downregulated at least one of the anti-apoptotic proteins, Bcl-xL, survivin or XIAP in all hepatoma cells. AG490 sensitized Huh-1, Huh-7 and HepG2 to TRAIL-induced apoptosis in vitro. Intraperitoneal injection of AG490, the combination of AG490 and TRAIL more greatly, repressed the growth of subcutaneous Huh-7 tumors in athymic mice. CONCLUSIONS Abrogation of constitutive activation of STAT3 by AG490 enhances the anti-tumor activity of TRAIL against human hepatoma cells.
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Affiliation(s)
- Mariko Kusaba
- First Department of Internal Medicine, Nagasaki University School of Medicine, 1-7-1, Sakamoto, Nagasaki 852-8501, Japan
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277
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STAT3 signaling is induced by intercellular adhesion in squamous cell carcinoma cells. Exp Cell Res 2007; 314:377-86. [PMID: 17961551 DOI: 10.1016/j.yexcr.2007.09.018] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2007] [Revised: 08/27/2007] [Accepted: 09/22/2007] [Indexed: 10/22/2022]
Abstract
The signal transducer and activator of transcription-3 (STAT3) frequently activated during tumor progression has been linked to enhanced cell growth. In squamous cell carcinoma of the head and neck (HNSCC), STAT3 signaling has been shown to inhibit apoptosis and induce a more aggressive phenotype through the activation of specific signaling pathways. In the present study, we have examined the potential mechanism by which cell-cell contact initiates STAT3 activation. Using a panel of HNSCC cell lines, Ca(+2)-dependent cell-cell adhesion and adherens junction formation in multicellular aggregates triggered phosphorylation of STAT3-Y705 and STAT1-Y701. This intercellular adhesion-induced STAT3 activation was mediated by JAK and Src signaling and partially by EGFR signaling. In addition, immunolocalization studies revealed initial formation of phosphorylated STAT3-Y705 at nascent E-cadherin cell junctions with eventual translocation to the nucleus in cell aggregates. Adhesion-mediated STAT activation in monolayer and cell aggregate cultures required functional E-cadherin. These results indicate that, in HNSCC cells, cadherin-mediated intercellular adhesion induces STAT signaling that may modulate cell survival and resistance to apoptosis during tumor progression.
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278
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Park Y, Shon SK, Kim A, Kim KI, Yang Y, Cho DH, Lee MS, Lim JS. SOCS1 induced by NDRG2 expression negatively regulates STAT3 activation in breast cancer cells. Biochem Biophys Res Commun 2007; 363:361-7. [PMID: 17888401 DOI: 10.1016/j.bbrc.2007.08.195] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2007] [Accepted: 08/28/2007] [Indexed: 12/22/2022]
Abstract
Although NDRG2 inactivation has recently been found to have an important role in some tumorigenesis, its role in intracellular signal transduction pathways remains poorly defined. In the present study, we demonstrate that NDRG2 overexpression in malignant breast cancer cells specifically inhibits Akt phosphorylation and induces phosphorylation of p38 MAP kinase and SAPK/JNK. In addition, we investigated whether NDRG2 expression affects JAK/STAT- or mitogen-activated protein kinase-mediated signal activation. JAK2 or STAT3 activation in both resting and IGF-stimulating cells was remarkably inhibited by NDRG2 expression. Furthermore, NDRG2 has been found to highly up-regulate the expression level of SOCS1 mRNA and protein. We have found that NDRG2 was able to regulate cytokine signaling in breast cancer cells through the regulation of SOCS1 expression. Finally, inhibition of p38 MAPK activity blocked the induction of SOCS1 expression by NDRG2, resulting in the recovery of STAT3 phosphorylation level. Together, these data demonstrate that NDRG2 expression in breast cancer cells is able to inhibit STAT3 activation via SOCS1 induction in a p38 MAPK dependent manner, implicating NDRG2 as a growth inhibitory gene in signal transduction pathways of breast tumor cells.
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Affiliation(s)
- Yongjin Park
- Department of Biological Sciences and the Research Center for Women's Diseases, Sookmyung Women's University, Chungpa-Dong, Yongsan-Gu, Seoul 140-742, Republic of Korea
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279
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Weaver AM, Silva CM. S731 in the transactivation domain modulates STAT5b activity. Biochem Biophys Res Commun 2007; 362:1026-30. [PMID: 17822672 PMCID: PMC2041903 DOI: 10.1016/j.bbrc.2007.08.087] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2007] [Accepted: 08/17/2007] [Indexed: 12/25/2022]
Abstract
As mediators of cytokine and growth factor signaling, signal transducers and activators of transcription (STATs) transmit signals from the membrane and cytoplasm to the nucleus. While Y699 phosphorylation is required for STAT5b transcriptional activity, our previous studies show that mutation of two tyrosines in the transactivation domain of STAT5b (Y740/743F) increases Y699 phosphorylation leading to increased transcriptional activity and DNA synthesis in breast cancer cells [A.M. Weaver, C.M. Silva, Modulation of signal transducer and activator of transcription 5b activity in breast cancer cells by mutation of tyrosines within the transactivation domain, Molecular Endocrinology 20 (2006) 2392-2405]. In many instances, phosphorylation of serines in the transactivation domain also modulates STAT5b activity. Here, we demonstrate for the first time that EGF stimulation enhances S731 phosphorylation. Furthermore, we show that the increased activity of the Y740/743F STAT5b mutant requires S731. As STAT5b is implicated in several cancers, understanding how its activity is regulated through tyrosine and serine phosphorylation is vital for the development of potential novel cancer therapeutics.
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Affiliation(s)
- Amanda M Weaver
- Department of Medicine and the Cancer Center, University of Virginia, Charlottesville, VA 22908, USA
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280
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Ling X, Konopleva M, Zeng Z, Ruvolo V, Stephens LC, Schober W, McQueen T, Dietrich M, Madden TL, Andreeff M. The novel triterpenoid C-28 methyl ester of 2-cyano-3, 12-dioxoolen-1, 9-dien-28-oic acid inhibits metastatic murine breast tumor growth through inactivation of STAT3 signaling. Cancer Res 2007; 67:4210-8. [PMID: 17483332 DOI: 10.1158/0008-5472.can-06-3629] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
We and others have reported that C-28 methyl ester of 2-cyano-3, 12-dioxoolen-1, 9-dien-28-oic acid (CDDO-Me) effectively inhibits the growth of multiple cancer cell types. Our previous studies indicated that prolonged CDDO-Me treatment inactivated extracellular signal-regulated kinase signaling in acute myelogenous leukemia cells. Whether treatment with CDDO-Me has an earlier effect on other proteins that are important for either signal transduction or oncogenesis is unknown. Constitutively activated signal transducer and activator of transcription 3 (STAT3) is frequently found in human breast cancer samples. Constitutively activated STAT3 was shown to up-regulate c-Myc in several types of cancer and has a feedback effect on Src and Akt. To examine the effects of CDDO-Me on STAT3 signaling in breast cancer, we used the murine 4T1 breast tumor model, which is largely resistant to chemotherapy. In vitro, after treatment of 4T1 cells with 500 nmol/L CDDO-Me for 2 h, we found (a) inactivation of STAT3, (b) inactivation of Src and Akt, (c) 4-fold reduction of c-Myc mRNA levels, (d) accumulation of cells in G(2)-M cell cycle phase, (e) abrogation of invasive growth of 4T1 cells, and (f) lack of apoptosis induction. In in vivo studies, CDDO-Me completely eliminated 4T1 breast cancer growth and lung metastases induced by 4T1 cells in mice when treatment started 1 day after tumor implantation and significantly inhibited tumor growth when started after 5 days. In vivo studies also indicated that splenic mature dendritic cells were restored after CDDO-Me treatment. In summary, these data suggest that CDDO-Me may have therapeutic potential in breast cancer therapy, in part, through inactivation of STAT3.
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Affiliation(s)
- Xiaoyang Ling
- Section of Molecular Hematology and Therapy, Department of Stem Cell Transplantation and Cellular Therapy, The University of Texas M. D. Anderson Cancer Center, Houston, Texas 77030, USA
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281
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Dimri M, Naramura M, Duan L, Chen J, Ortega-Cava C, Chen G, Goswami R, Fernandes N, Gao Q, Dimri GP, Band V, Band H. Modeling breast cancer-associated c-Src and EGFR overexpression in human MECs: c-Src and EGFR cooperatively promote aberrant three-dimensional acinar structure and invasive behavior. Cancer Res 2007; 67:4164-72. [PMID: 17483327 DOI: 10.1158/0008-5472.can-06-2580] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Epidermal growth factor receptor (EGFR), a member of the ErbB family of receptor tyrosine kinases, is overexpressed in as many as 60% cases of breast and other cancers. EGFR overexpression is a characteristic of highly aggressive molecular subtypes of breast cancer with basal-like and BRCA1 mutant phenotypes distinct from ErbB2-overexpressing breast cancers. Yet, EGFR is substantially weaker compared with ErbB2 in promoting the oncogenic transformation of nontumorigenic human mammary epithelial cells (human MEC), suggesting a role for cooperating oncogenes. Here, we have modeled the co-overexpression of EGFR and a biologically and clinically relevant potential modifier c-Src in two distinct immortal but nontumorigenic human MECs. Using a combination of morphologic analysis and confocal imaging of polarity markers in three-dimensional Matrigel culture together with functional analyses of early oncogenic traits, we show for the first time that EGFR and c-Src co-overexpression but not EGFR or c-Src overexpression alone unleashes an oncogenic signaling program that leads to hyperproliferation and loss of polarity in three-dimensional acinar cultures, marked enhancement of migratory and invasive behavior, and anchorage-independent growth. Our results establish that EGFR overexpression in an appropriate context (modeled here using c-Src overexpression) can initiate oncogenic transformation of nontumorigenic human MECs and provide a suitable in vitro model to interrogate human breast cancer-relevant oncogenic signaling pathways initiated by overexpressed EGFR and to identify modifiers of EGFR-mediated breast oncogenesis.
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Affiliation(s)
- Manjari Dimri
- Division of Molecular Oncology, Evanston Northwestern Healthcare Research Institute, Evanston, IL 60201, USA
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282
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Gautschi O, Mack PC, Heighway J, Gumerlock PH, Gandara DR. Molecular Biology of Lung Cancer as the Basis for Targeted Therapy. Lung Cancer 2007. [DOI: 10.3109/9781420020359.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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283
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Abstract
Advances in the understanding of glioma pathogenesis have led to increasing interest in the development of targeted molecular agents, and especially kinase inhibitors, for treatment of malignant gliomas. Protein kinases are a large family of enzymes that function as key regulators of cellular signaling pathways governing diverse functions, such as cell proliferation, growth, differentiation, invasion, angiogenesis and apoptosis in malignant gliomas. Preliminary clinical results with kinase inhibitors suggest that they are generally well-tolerated but have shown only modest activity. However, valuable information was obtained from these early clinical trials that will help the future development of these agents. This article reviews the important protein kinases in malignant gliomas, summarizes the existing clinical development of kinase inhibitors and discusses strategies to improve their effectiveness.
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Affiliation(s)
- Andrew S Chi
- Center For Neuro-Oncology, Dana-Farber/Brigham and Women's Cancer Center, Shields-Warren 430D, 44 Binney Street, Boston, MA 02115, USA
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284
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Shor AC, Keschman EA, Lee FY, Muro-Cacho C, Letson GD, Trent JC, Pledger WJ, Jove R. Dasatinib inhibits migration and invasion in diverse human sarcoma cell lines and induces apoptosis in bone sarcoma cells dependent on SRC kinase for survival. Cancer Res 2007; 67:2800-8. [PMID: 17363602 DOI: 10.1158/0008-5472.can-06-3469] [Citation(s) in RCA: 190] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Sarcomas are rare malignant mesenchymal tumors for which there are limited treatment options. One potential molecular target for sarcoma treatment is the Src tyrosine kinase. Dasatinib (BMS-354825), a small-molecule inhibitor of Src kinase activity, is a promising cancer therapeutic agent with p.o. bioavailability. Dasatinib exhibits antitumor effects in cultured human cell lines derived from epithelial tumors, including prostate and lung carcinomas. However, the action of dasatinib in mesenchymally derived tumors has yet to be shown. Based on our previous findings of Src activation in human sarcomas, we evaluated the effects of dasatinib in 12 cultured human sarcoma cell lines derived from bone and soft tissue sarcomas. Dasatinib inhibited Src kinase activity at nanomolar concentrations in these sarcoma cell lines. Downstream components of Src signaling, including focal adhesion kinase and Crk-associated substrate (p130(CAS)), were also inhibited at similar concentrations. This inhibition of Src signaling was accompanied by blockade of cell migration and invasion. Moreover, apoptosis was induced in the osteosarcoma and Ewing's subset of bone sarcomas at nanomolar concentrations of dasatinib. Inhibition of Src protein expression by small interfering RNA also induced apoptosis, indicating that these bone sarcoma cell lines are dependent on Src activity for survival. These results show that dasatinib inhibits migration and invasion of diverse sarcoma cell types and selectively blocks the survival of bone sarcoma cells. Therefore, dasatinib may provide therapeutic benefit by preventing the growth and metastasis of sarcomas in patients.
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Affiliation(s)
- Audrey C Shor
- Gonzmart Laboratory, Sarcoma Program, H. Lee Moffitt Cancer Center and Research Institute, Tampa, Florida, USA
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285
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Abstract
BACKGROUND Carcinoma of the prostate (CaP) is the most commonly diagnosed cancer in men in the United States. Signal transduction molecules such as tyrosine kinases play important roles in CaP. Src, a nonreceptor tyrosine kinase (NRTK) and the first proto-oncogene discovered is shown to participate in processes such as cell proliferation and migration in CaP. Underscoring NRTK's and, specifically, Src's importance in cancer is the recent approval by the US Food and Drug Administration of dasatinib, the first commercial Src inhibitor for clinical use in chronic myelogenous leukemia (CML). In this review we will focus on NRTKs and their roles in the biology of CaP. MATERIALS AND METHODS Publicly available literature from PubMed regarding the topic of members of NRTKs in CaP was searched and reviewed. RESULTS Src, FAK, JaK1/2, and ETK are involved in processes indispensable to the biology of CaP: cell growth, migration, invasion, angiogenesis, and apoptosis. CONCLUSIONS Src emerges as a common signaling and regulatory molecule in multiple biological processes in CaP. Src's relative importance in particular stages of CaP, however, required further definition. Continued investigation of NRTKs will increase our understanding of their biological function and potential role as new therapeutic targets.
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Affiliation(s)
- Yu-Ming Chang
- Department of Urology, University of California at Davis, Sacramento, CA 95817, USA
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286
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Aboudola S, Murugesan G, Szpurka H, Ramsingh G, Zhao X, Prescott N, Tubbs RR, Maciejewski JP, Hsi ED. Bone Marrow Phospho-STAT5 Expression in Non-CML Chronic Myeloproliferative Disorders Correlates With JAK2 V617F Mutation and Provides Evidence of In Vivo JAK2 Activation. Am J Surg Pathol 2007; 31:233-9. [PMID: 17255768 DOI: 10.1097/01.pas.0000213338.25111.d3] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The recently described JAK2 V617F mutation, present in a substantial proportion of nonchronic myelogenous leukemia chronic myeloproliferative disorders (non-CML CMPDs), is changing the way we conceptualize and diagnose these diseases. We hypothesized that the activation of this tyrosine kinase might result in activation of downstream mediators such as STAT5, which would be detectable in bone marrow biopsies. We examined the expression of activated STAT5 (nuclear phospho-STAT5) in 73 bone marrow biopsies from patients with CMPDs [20 essential thrombocythemia (ET), 26 chronic idiopathic myelofibrosis (CIMF), and 27 polycythemia vera] and 39 controls. We compared the results with the JAK2 mutational status and clinical parameters. The frequency of the JAK2 V617F was 73% (85% in PV, 65% in ET, and 65% in CIMF). All patients with the JAK2 V617F showed abnormal nuclear megakaryocytic phospho-STAT5 (nMEG pSTAT5) expression. In the JAK2 wild-type group, nMEG pSTAT5 was observed in 2/7 ET, and 3/9 CIMF patients. nMEG pSTAT5 staining was 100% sensitive and 88% specific for JAK2 V617F. Clinically, nMEG pSTAT5+ patients seemed to require cytoreductive therapy more often than those without nMEG p-STAT expression. pSTAT5 immunohistochemistry is a useful diagnostic test in bone marrow biopsies from suspected non-CML CMPD patients. It identifies most of the patients with the JAK2 V617F but also other JAK2 wild-type CMPD patients. The presence of nMEG pSTAT5 in a subset of CMPD patients lacking the mutation suggests that alternate tyrosine kinase/phosphatase pathways may be involved and warrant further investigation. Phosphoprotein detection represents a new area for diagnostic pathology that exploits specific functional characteristics of cells within the context of a tissue section.
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Affiliation(s)
- Samer Aboudola
- Department of Clinical pathology and Laboratory Medicine, Taussig Cancer Center, The Cleveland Clinic Foundation, Cleveland, OH 44195, USA
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287
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Shelton JG, Steelman LS, Abrams SL, Bertrand FE, Franklin RA, McMahon M, McCubrey JA. The epidermal growth factor receptor gene family as a target for therapeutic intervention in numerous cancers: what's genetics got to do with it? Expert Opin Ther Targets 2007; 9:1009-30. [PMID: 16185155 DOI: 10.1517/14728222.9.5.1009] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Over the past 30 years, a relatively simple growth factor and its cognate receptor have provided seminal insights into the understanding of the genetic basis of cancer, as well as growth factor signalling. The epidermal growth factor (EGF), its cognate receptor (EGFR) and related family members have been shown to be important in normal, as well as the malignant growth of many cell types including: glioblastomata, astrocytomas, medulloblastomata, non-small cell lung carcinoma (NSCLC) and breast cancer. This review summarises the history of the EGFR gene and the v-ErbB oncogene, as well as diverse approaches developed to inhibit EGFR activity. The two most advanced therapies use either small-molecule cell membrane permeable kinase inhibitors or antibodies which prevent receptor activation. Recent clinical trials indicate that certain NSCLC patients have mutations in the EGFR gene which makes them more responsive to kinase inhibitors. These mutations appear to enhance the ability of the ligand to activate EGFR activity and also prolong the binding of the EGFR inhibitor to the kinase domain. Evidence to date suggests that these EGFR mutations in NSCLC occur more frequently in Japan than in the western hemisphere. Although these mutations are correlated with enhanced efficacy to the inhibitors in NSCLC, they can not explain or predict the sensitivity of many other cancer patients to the beneficial effects of the EGFR kinase inhibitors or antibody mediated therapy. As with as other small-molecule kinase inhibitors and susceptible diseases (e.g., imatinib and chronic myeloid leukaemia), resistance to EGFR inhibitors has been reported recently, documenting the requirement for development of multi-pronged therapeutic approaches. EGFR kinase inhibitors are also being evaluated as adjuvants in hormonal therapy of breast cancer - especially those which overexpress EGFR. Genetically engineered antibodies specific for the EGFR family member ErbB2 have been developed which show efficacy in the treatment of primary, and prevent the relapse of, breast cancer. Clearly, the EGF/EGFR signalling cascade has, and continues to play, an important role in the development of novel anticancer targeted therapies.
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Affiliation(s)
- John G Shelton
- Brody School of Medicine at East Carolina University, Department of Microbiology & Immunology, Greenville, NC 27858, USA
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288
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Okamoto M, Hayakawa F, Miyata Y, Watamoto K, Emi N, Abe A, Kiyoi H, Towatari M, Naoe T. Lyn is an important component of the signal transduction pathway specific to FLT3/ITD and can be a therapeutic target in the treatment of AML with FLT3/ITD. Leukemia 2007; 21:403-10. [PMID: 17230226 DOI: 10.1038/sj.leu.2404547] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Fms-like tyrosine kinase 3 (FLT3) is expressed in hematopoietic progenitor cells. An internal tandem duplication (ITD) of FLT3 (FLT3/ITD) is the most frequent mutation in human adult acute myeloid leukemia (AML). FLT3/ITD contributes to the constitutive activation of FLT3 itself and its downstream signal components, mitogen-activated protein kinase and signal transducers and activators of transcription 5 (STAT5), and enables interleukin (IL)-3-dependent cell lines to grow autonomously. In the present study, we showed the specific association of FLT3/ITD with Lyn, which led to the phosphorylation of Lyn in vivo. We also demonstrated that FLT3/ITD receptors displayed a higher affinity to bind to Lyn than wild-type FLT3 receptors in vitro and that this affinity was relative to the intensity of tyrosil phosphorylation of the receptor. Both treatment with small interfering RNA (siRNA) targeting Lyn and the Src family kinase inhibitor PP2 suppressed the IL-3-independent growth of FLT3/ITD-expressing 32D cells (FLT3/ITD-32D), reducing the constitutive phosphorylation of Lyn and STAT5. PP2 treatment of mice transplanted with FLT3/ITD-32D cells blocked the onset of tumors and decreased the size of established tumors. These results demonstrate that Lyn is an important component of the signal transduction pathway specific to FLT3/ITD and can be a therapeutic target in the treatment of AML with FLT3/ITD.
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Affiliation(s)
- M Okamoto
- 1Department of Hematology and Oncology, Nagoya University Graduate School of Medicine, Nagoya, Japan
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289
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Payne SL, Hendrix MJC, Kirschmann DA. Paradoxical roles for lysyl oxidases in cancer—A prospect. J Cell Biochem 2007; 101:1338-54. [PMID: 17471532 DOI: 10.1002/jcb.21371] [Citation(s) in RCA: 177] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Lysyl oxidase (LOX) is an extracellular matrix (ECM) enzyme that catalyzes the cross-linking of collagens or elastin in the extracellular compartment, thereby regulating the tensile strength of tissues. However, recent reports have demonstrated novel roles for LOX, including the ability to regulate gene transcription, motility/migration, and cell adhesion. These diverse functions have led researchers to hypothesize that LOX may have multiple roles affecting both extra- and intracellular cell function(s). Particularly noteworthy is aberrant LOX expression and activity that have been observed in various cancerous tissues and neoplastic cell lines. Both down and upregulation of LOX in tumor tissues and cancer cell lines have been described, suggesting a dual role for LOX as a tumor suppressor, as well as a metastasis promoter gene--creating a conundrum within the LOX research field. Here, we review the body of evidence on LOX gene expression, regulation, and function(s) in various cancer cell types and tissues, as well as stromal-tumor cell interactions. Lastly, we will examine putative mechanisms in which LOX facilitates breast cancer invasion and metastasis. Taken together, the literature demonstrates the increasingly important role(s) that LOX may play in regulating tumor progression and the necessity to elucidate its myriad mechanisms of action in order to identify potentially novel therapeutics.
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Affiliation(s)
- Stacey L Payne
- Children's Memorial Research Center, Division of Cancer Biology and Epigenomics, Robert H. Lurie Comprehensive Cancer Center, Feinberg School of Medicine at Northwestern University, Chicago, IL 60614, USA
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290
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Munk M, Memon AA, Nexo E, Sorensen BS. Inhibition of the epidermal growth factor receptor in bladder cancer cells treated with the DNA-damaging drug etoposide markedly increases apoptosis. BJU Int 2007; 99:196-201. [PMID: 17092291 DOI: 10.1111/j.1464-410x.2006.06510.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
OBJECTIVE To investigate the effect of the epidermal growth factor receptor (EGFR) on the induction of apoptosis by the chemotherapeutic agent etoposide (VP16), and to examine the effect of combining VP16 with gefitinib to see if the cell-survival mechanism can be prevented. MATERIALS AND METHODS The bladder cancer cell lines RT4 and T24, representing low- and high-malignancy grades respectively, were treated with VP16 (10 or 50 microM) and the level of apoptosis determined using a commercial kit. EGFR receptor activity was determined by western blotting using antibodies against phosphorylated EGFR. The EGFR was either activated by heparin-binding (HB)-EGF (1 nM) or inhibited with the specific EGFR inhibitor gefitinib (1 or 5 microM). The pan-caspase inhibitor Z-VAD (30 microM) was used to test the involvement of caspase activity. RESULTS Treatment of T24 bladder cancer cells with VP16 (50 microM) for 48 h induced phosphorylation of the EGFR and activation of the EGFR prevented the apoptosis induced by VP16. Thus, treatment of T24 cells with 50 microM VP16 for 48 h resulted in 19% apoptosis. However, activation of the EGFR with HB-EGF (1 nM) with VP16 (50 microM) significantly reduced the level of apoptosis by 25% (P < 0.05) showing that activating the EGFR has a cell-survival function. Inhibiting the EGFR with gefitinib (5 microM) blocked the VP16-induced activation of the EGFR. Combined treatment with gefitinib and VP16 resulted in 45% apoptotic cells, i.e. more than double the percentage of apoptotic cells with VP16 alone. This was found in both T24 and RT4 cells. Gefitinib used alone (1 and 5 microM) generated no apoptosis in the cells. Treatment of T24 cells with Z-VAD showed that apoptosis induced by both VP16 alone and VP16 with gefitinib was caspase-mediated. CONCLUSION These results suggest that activation of the EGFR induced a cell-survival function when bladder cancer cells were treated with the DNA-damaging drug VP16, and that combined treatment with VP16 and the EGFR inhibitor gefitinib might improve the efficacy of treatment.
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Affiliation(s)
- Mathias Munk
- Department of Clinical Biochemistry, Aarhus University Hospital NBG, Aarhus, Denmark
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291
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McCarty MF, Block KI. Preadministration of high-dose salicylates, suppressors of NF-kappaB activation, may increase the chemosensitivity of many cancers: an example of proapoptotic signal modulation therapy. Integr Cancer Ther 2006; 5:252-68. [PMID: 16880431 DOI: 10.1177/1534735406291499] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
NF-kappaB activity is elevated in a high proportion of cancers, particularly advanced cancers that have been treated previously. Cytotoxic treatment selects for such up-regulation inasmuch as NF-kappaB promotes transcription of a large number of proteins that inhibit both the intrinsic and extrinsic pathways of apoptosis; NF-kappaB also boosts expression of mdr1, which expels many drugs from cells. Indeed, high NF-kappaB activity appears to be largely responsible for the chemo- and radioresistance of many cancers. Thus, agents that suppress NF-kappaB activity should be useful as adjuvants to cytotoxic cancer therapy. Of the compounds that are known to be NF-kappaB antagonists, the most practical for current use may be the nonsteroidal anti-inflammatory drugs aspirin, salicylic acid, and sulindac, each of which binds to and inhibits Ikappa kinase- beta, a central mediator of NF-kappa activation; the low millimolar plasma concentrations of salicylate required for effective inhibition of this kinase in vivo can be achieved with high-dose regimens traditionally used to manage rheumatic disorders. The gastrointestinal toxicity of such regimens could be minimized by using salsalate or enteric-coated sodium salicy-late or by administering misoprostol in conjunction with aspirin therapy. Presumably, best results would be seen if these agents were administered for several days prior to a course of chemo- or radiotherapy, continuing throughout the course. This concept should first be tested in nude mice bearing xenografts of chemoresistant human tumors known to have elevated NF-kappa activity. Ultimately, more complex adjuvant regimens can be envisioned in which salicylates are used in conjunction with other NF-kappa antagonists and/or agents that target other mediators of down-regulated apoptosis in cancer, such as Stat3; coadministration of salicylate and organic selenium may have intriguing potential in this regard. These strategies may also have potential as adjuvants to metronomic chemotherapy, which seeks to suppress angio-genesis by targeting cycling endothelial cells in tumors.
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Affiliation(s)
- Mark F McCarty
- Block Center for Integrative Cancer Care, Evanston, Illinois 60201, USA
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292
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Pedranzini L, Dechow T, Berishaj M, Comenzo R, Zhou P, Azare J, Bornmann W, Bromberg J. Pyridone 6, A Pan-Janus–Activated Kinase Inhibitor, Induces Growth Inhibition of Multiple Myeloma Cells. Cancer Res 2006; 66:9714-21. [PMID: 17018630 DOI: 10.1158/0008-5472.can-05-4280] [Citation(s) in RCA: 130] [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
Interleukin-6 (IL-6) and the subsequent Janus-activated kinase (JAK)-dependent signaling pathways play a critical role in the pathogenesis of multiple myeloma. Here, we compared the sensitivity and specificity of a novel pan-JAK inhibitor, tetracyclic pyridone 6 (P6), with that of AG490 in a panel of myeloma-derived cell lines. P6 induced growth arrest and subsequent apoptosis of the IL-6-dependent hybridoma and myeloma-derived cell lines (B9 and INA-6) grown either in IL-6-containing medium or in the presence of bone marrow-derived stromal cells (BMSC) using much lower concentrations of drug and with significantly faster kinetics than AG490. Myeloma-derived cell lines, which either express constitutively activated JAK/signal transducers and activators of transcription (STAT) 3 (U266) or are IL-6 growth stimulated (KMS11), are partially growth inhibited by P6. However, P6 does not inhibit the growth of myeloma-derived cell lines lacking activated JAKs/STATs nor does it inhibit mitogen-activated protein kinase/extracellular signal-regulated kinase (ERK) kinase activity compared with AG490, which led to activation of ERK and induced robust apoptosis of all the examined cell lines. Finally, P6 inhibited the growth of primary myeloma patient samples grown in the presence of BMSCs. Thus, P6 is a more sensitive and specific inhibitor of JAK-STAT3 activity compared with AG490 and potently inhibited the growth of primary myeloma cells and myeloma-derived cell lines grown on BMSCs.
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Affiliation(s)
- Laura Pedranzini
- Department of Medicine, Memorial Sloan-Kettering Cancer Center, New York, NY 10021, USA
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293
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Arbouzova NI, Zeidler MP. JAK/STAT signalling in Drosophila: insights into conserved regulatory and cellular functions. Development 2006; 133:2605-16. [PMID: 16794031 DOI: 10.1242/dev.02411] [Citation(s) in RCA: 298] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
High levels of interspecies conservation characterise all signal transduction cascades and demonstrate the significance of these pathways over evolutionary time. Here, we review advances in the field of JAK/STAT signalling, focusing on recent developments in Drosophila. In particular, recent results from genetic and genome-wide RNAi screens, as well as studies into the developmental roles played by this pathway, highlight striking levels of physical and functional conservation in processes such as cellular proliferation, immune responses and stem cell maintenance. These insights underscore the value of model organisms for improving our understanding of this human disease-relevant pathway.
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Affiliation(s)
- Natalia I Arbouzova
- Department of Molecular Developmental Biology, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077 Göttingen, Germany
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294
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Trevino JG, Gray MJ, Nawrocki ST, Summy JM, Lesslie DP, Evans DB, Sawyer TK, Shakespeare WC, Watowich SS, Chiao PJ, McConkey DJ, Gallick GE. Src activation of Stat3 is an independent requirement from NF-kappaB activation for constitutive IL-8 expression in human pancreatic adenocarcinoma cells. Angiogenesis 2006; 9:101-10. [PMID: 16871430 DOI: 10.1007/s10456-006-9038-9] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2006] [Accepted: 06/14/2006] [Indexed: 11/28/2022]
Abstract
Human pancreatic tumors often overexpress the angiogenesis-promoting factor Interleukin 8 (IL-8), in part due to overexpression of NF-kappaB, a frequent occurrence in pancreatic adenocarcinoma. In this study, we demonstrate that reducing c-Src kinase activity, through either pharmacologic inhibition or small interfering RNA-targeted reduction of Src expression, significantly decreased IL-8 expression (P < 0.05) without affecting NF-kappaB-mediated transcription, but by decreasing phosphorylation of STAT3. To ascertain whether Src-mediated expression of IL-8 was dependent on STAT3, we used stable clones expressing a dominant-negative isoform of STAT3 that inhibits endogenous STAT3 phosphorylation and subsequent DNA binding and STAT3-mediated gene expression or a constitutively activated isoform of STAT3. IL-8 expression was significantly lower in clones expressing the dominant-negative isoform and significantly increased in clones expressing the activated isoform (P < 0.05 for both). Pharmacologic inhibition of NF-kappaB activity significantly reduced basal IL-8 expression and tumor necrosis factor-induced IL-8 expression (P < 0.05 for both), yet NF-kappaB activity was not dependent on Src. We therefore suggest that Src activation, through phosphorylation of STAT3, and NF-kappaB are all required for expression of IL-8 a critical angiogenic-promoting factor in pancreatic adenocarcinomas.
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Affiliation(s)
- Jose G Trevino
- Department of Cancer Biology, Unit 179, The University of Texas M D Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, TX 77030, USA
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295
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Han C, Demetris AJ, Stolz DB, Xu L, Lim K, Wu T. Modulation of Stat3 activation by the cytosolic phospholipase A2alpha and cyclooxygenase-2-controlled prostaglandin E2 signaling pathway. J Biol Chem 2006; 281:24831-46. [PMID: 16790433 DOI: 10.1074/jbc.m602201200] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
A variety of human cancers show constitutive activation of signal transducer and activator of transcription-3 (Stat3) and overexpression of cyclooxygenase-2 (COX-2). This study describes a novel cross-talk between the COX-2-controlled prostaglandin E(2) (PGE(2)) and Stat3 signaling pathways that coordinately regulate human cancer cell growth. COX-2-derived PGE(2) induces interleukin-6 production through activation of EP(4) receptor and subsequent phosphorylation of gp130/Stat3 in human cholangiocarcinoma cells. In parallel, activation of COX-2/PGE(2) signaling also enhances Stat3 phosphorylation and reporter activity through EP(1) receptor-induced activation of c-Src and EGFR in these cells. Moreover, the observations that EP(1) receptor is detected in the nucleus as well as in the Stat3.DNA binding complex and that activation of EP(1) receptor in the nuclei enhances Stat3 activation depicts a previously undescribed G protein-coupled receptor in the nucleus for Stat3 activation and tumor cell growth.
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Affiliation(s)
- Chang Han
- Department of Pathology, University of Pittsburgh, Pittsburgh, Pennsylvania 15213, USA. changhan+@pitt.edu
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296
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Nakasato M, Shirakura Y, Ooga M, Iwatsuki M, Ito M, Kageyama SI, Sakai S, Nagata M, Aoki F. Involvement of the STAT5 signaling pathway in the regulation of mouse preimplantation development. Biol Reprod 2006; 75:508-17. [PMID: 16775227 DOI: 10.1095/biolreprod.105.047860] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
The signal transducer and activator of transcription 5 (STAT5) is an essential factor in the signal transduction pathways for a number of cytokines that regulate the growth and differentiation of mammalian cells. In this study, we investigated the STAT5 signaling pathway in mouse embryos, to elucidate the mechanism of cytokine signal transduction that regulates preimplantation development. The results of the RT-PCR analysis showed that both STAT5A and B were expressed throughout preimplantation development. Immunocytochemistry revealed that the STAT5A/B proteins were located in the nucleus from the early 1-cell stage to the blastocyst stage. STAT5 activation appeared to be regulated by Janus kinases (JAKs) and SRC family kinases (SFKs), since inhibitors of these kinases inhibited the localization of STAT5 proteins to the nucleus. The JAK inhibitor Ag490 reduced both the developmental rate of the embryos and the expression levels of the downstream genes of the JAK-STAT5 signaling pathway. These findings suggest that STAT5 proteins function in preimplantation development by mediating the signals from cytokines.
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Affiliation(s)
- Makoto Nakasato
- Department of Integrated Biosciences, Graduate School of Frontier Sciences, University of Tokyo, Chiba 277-8562, Japan
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297
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Graness A, Poli V, Goppelt-Struebe M. STAT3-independent inhibition of lysophosphatidic acid-mediated upregulation of connective tissue growth factor (CTGF) by cucurbitacin I. Biochem Pharmacol 2006; 72:32-41. [PMID: 16707113 DOI: 10.1016/j.bcp.2006.04.001] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2006] [Revised: 03/28/2006] [Accepted: 04/07/2006] [Indexed: 11/21/2022]
Abstract
Cucurbitacins are recognised as anti-tumour agents because of their interference with STAT3 signalling, but may also affect the integrity of the actin cytoskeleton. In the present study the effect of cucurbitacin I was investigated in fibroblasts. In these cells, cucurbitacin I interfered with lysophosphatidic acid (LPA) signalling. It inhibited tyrosine phosphorylation of focal adhesion proteins and induction of connective tissue growth factor (CTGF), a potent profibrotic protein. Inhibition of Src family kinases with PP2, but not the inactive analogue PP3, also interfered with LPA-mediated tyrosine phosphorylation and induction of CTGF. Jak2-STAT3 signalling seemed to be the connecting link, because CTGF induction was sensitive to AG490, an inhibitor of Jak2, and cucurbitacin I, an inhibitor of Jak2 and STAT3. However, LPA did not activate tyrosine phosphorylation of STAT3. Furthermore, cucurbitacin I was as effective in STAT3 knock out cells as in control cells. Therefore, the inhibitory effect of cucurbitacin I was not related to inhibition of STAT3. Immunocytochemical analysis of cucurbitacin I-treated cells revealed disassembly of F-actin fibres, reorganisation into F-actin patches and resolution of focal adhesions. The phenotypic changes resembled changes observed after treatment of the cells with cytochalasin D, which has been shown to interfere with CTGF induction. Concentrations of cucurbitacin I, which have been shown to target Jak2-STAT3 signalling, thus, profoundly affect the actin cytoskeleton and may therefore modulate cell morphology, migration, adherence and gene expression also in non-tumour cells.
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Affiliation(s)
- Angela Graness
- Department of Nephrology and Hypertension, University of Erlangen-Nuremberg, Loschgestrasse 8, D-91054 Erlangen, Germany
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298
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Karur VG, Lowell CA, Besmer P, Agosti V, Wojchowski DM. Lyn kinase promotes erythroblast expansion and late-stage development. Blood 2006; 108:1524-32. [PMID: 16705093 PMCID: PMC1895506 DOI: 10.1182/blood-2005-09-008243] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Lyn kinase is known to modulate the formation and function of B cells, monocytes, and mast cells. However, Lyn-/- mice also develop erythrosplenomegaly, and cases for both negative and positive erythropoietic actions of Lyn recently have been outlined. In phenylhydrazine-treated Lyn-/- mice, extramedullary splenic erythropoiesis was hyperactivated, but this did not lead to accelerated recovery from anemia. Furthermore, ex vivo analyses of the development of bone marrow-derived Lyn-/- erythroblasts in unique primary culture systems indicated positive roles for Lyn at 2 stages. Late-stage Lyn-/- erythroblasts exhibited deficit Ter119(pos) cell formation, and this was paralleled by increased apoptosis (and decreased Bcl-xL expression). During early development, Lyn-/- erythroblasts accumulated at a Kit(pos)CD71(high) stage, possessed decreased proliferative capacity, and were attenuated in entering an apparent G1/S cell-cycle phase. In proposed compensatory responses, Lyn-/- erythroblasts expressed increased levels of activated Akt and p60-Src and decreased levels of death-associated protein kinase-2. Stat5 activation and Bcl-xL expression, in contrast, were significantly decreased in keeping with decreased survival and developmental potentials. Lyn, therefore, is proposed to function via erythroid cell-intrinsic mechanisms to promote progenitor cell expansion beyond a Kit(pos)CD71(high) stage and to support subsequent late-stage development.
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Affiliation(s)
- Vinit G Karur
- Maine Medical Center Research Institute, 81 Research Dr, Scarborough, ME 04074, USA
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299
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Koon HW, Zhao D, Zhan Y, Rhee SH, Moyer MP, Pothoulakis C. Substance P stimulates cyclooxygenase-2 and prostaglandin E2 expression through JAK-STAT activation in human colonic epithelial cells. THE JOURNAL OF IMMUNOLOGY 2006; 176:5050-9. [PMID: 16585602 PMCID: PMC2593099 DOI: 10.4049/jimmunol.176.8.5050] [Citation(s) in RCA: 84] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Substance P (SP) via its neurokinin-1 receptor (NK-1R) regulates several gastrointestinal functions. We previously reported that NK-1R-mediated chloride secretion in the colon involves formation of PG. PGE2 biosynthesis is controlled by cyclooxygenase-1 (COX-1) and COX-2, whose induction involves the STATs. In this study, we examined whether SP stimulates PGE2 production and COX-2 expression in human nontransformed NCM460 colonocytes stably transfected with the human NK-1R (NCM460-NK-1R cells) and identified the pathways involved in this response. SP exposure time and dose dependently induced an early (1-min) phosphorylation of JAK2, STAT3, and STAT5, followed by COX-2 expression and PGE2 production by 2 h. Pharmacologic experiments showed that PGE2 production is dependent on newly synthesized COX-2, but COX-1 protein. Inhibition of protein kinase Ctheta (PKCtheta), but not PKCepsilon and PKCdelta, significantly reduced SP-induced COX-2 up-regulation, and JAK2, STAT3, and STAT5 phosphorylation. Pharmacological blockade of JAK inhibited SP-induced JAK2, STAT3, and STAT5 phosphorylation; COX-2 expression; and PGE2 production. Transient transfection with JAK2 short-interferring RNA reduced COX-2 promoter activity and JAK2 phosphorylation, while RNA interference of STAT isoforms showed that STAT5 predominantly mediates SP-induced COX-2 promoter activity. Site-directed mutation of STAT binding sites on the COX-2 promoter completely abolished COX-2 promoter activity. Lastly, COX-2 expression was elevated in colon of mice during experimental colitis, and this effect was normalized by administration of the NK-1R antagonist CJ-12,255. Our results demonstrate that SP stimulates COX-2 expression and PGE2 production in human colonocytes via activation of the JAK2-STAT3/5 pathway.
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Affiliation(s)
- Hon-Wai Koon
- Gastrointestinal Neuropeptide Center, Division of Gastroenterology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA
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300
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Reddy MA, Li SL, Sahar S, Kim YS, Xu ZG, Lanting L, Natarajan R. Key role of Src kinase in S100B-induced activation of the receptor for advanced glycation end products in vascular smooth muscle cells. J Biol Chem 2006; 281:13685-13693. [PMID: 16551628 DOI: 10.1074/jbc.m511425200] [Citation(s) in RCA: 125] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
The receptor for advanced glycation end products (RAGE) and its ligands have been implicated in the activation of oxidant stress and inflammatory pathways in vascular smooth muscle cells (VSMCs) leading to the initiation and augmentation of atherosclerosis. Here we report that non-receptor Src tyrosine kinase and the membrane protein caveolin-1 (Cav-1) play a key role in the activation of RAGE by S100B in VSMCs. S100B increased the activation of Src kinase and tyrosine phosphorylation of caveolin-1 in VSMCs. A RAGE-specific antibody blocked both these effects. An inhibitor of Src kinase, PP2, significantly blocked S100B-induced activation of Src kinase, mitogen-activated protein kinases, transcription factors NF-kappaB and STAT3, superoxide production, tyrosine phosphorylation of Cav-1, VSMC migration, and expression of the pro-inflammatory genes monocyte chemotactic protein-1 and interleukin-6. Cholesterol depletion also inhibited S100B-induced effects indicating the requirement for intact caveolae in RAGE-specific signaling. Nucleofection of either a Src dominant negative mutant, or a Cav-1 mutant lacking the scaffolding domain, or Cav-1 short hairpin RNA significantly reduced S100B-induced inflammatory gene expression in VSMCs. Furthermore, VSMCs derived from insulin-resistant and diabetic db/db mice displayed increased RAGE expression, Src activation, and migration compared with those from control db/+ mice. The RAGE antibody blocked enhanced migration in db/db cells. These studies demonstrate for the first time that, in VSMCs, Src kinase and Cav-1 play important roles in RAGE-mediated inflammatory gene expression and migration, key events associated with diabetic vascular complications.
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Affiliation(s)
- Marpadga A Reddy
- Department of Diabetes, Beckman Research Institute of the City of Hope, Duarte, California 91010
| | - Shu-Lian Li
- Department of Diabetes, Beckman Research Institute of the City of Hope, Duarte, California 91010
| | - Saurabh Sahar
- Department of Diabetes, Beckman Research Institute of the City of Hope, Duarte, California 91010
| | - Young-Sook Kim
- Department of Diabetes, Beckman Research Institute of the City of Hope, Duarte, California 91010
| | - Zhong-Gao Xu
- Department of Diabetes, Beckman Research Institute of the City of Hope, Duarte, California 91010
| | - Linda Lanting
- Department of Diabetes, Beckman Research Institute of the City of Hope, Duarte, California 91010
| | - Rama Natarajan
- Department of Diabetes, Beckman Research Institute of the City of Hope, Duarte, California 91010.
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