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Sun Y, Liu L, Wang Y, He A, Hu H, Zhang J, Han M, Huang Y. Curcumin inhibits the proliferation and invasion of MG-63 cells through inactivation of the p-JAK2/p-STAT3 pathway. Onco Targets Ther 2019; 12:2011-2021. [PMID: 30936718 PMCID: PMC6421868 DOI: 10.2147/ott.s172909] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Purpose The aims of this study were to determine the effect of curcumin on osteosarcoma (OS) cells due to inactivation of the p-JAK2/p-STAT3 pathway and evaluate the prognostic value of this pathway in OS. Materials and methods We exposed a human OS cell line (MG-63) to different concentrations of curcumin. Then, we characterized the effects on MG-63 cells using assays (cell viability, colony formation, cell cycle, wound healing, invasion), flow cytometry, Western blot, immunohistochemical analyses, and tumor xenograft. Results The half-maximal inhibitory of curcumin for MG-63 cells at 24 hours was 27.6 µM. The number of colonies of MG-63 cells was decreased obviously upon curcumin (10 and 20 µM) treatment. We also found increased accumulation of MG-63 cells in the G2/M phase upon curcumin (10 and 20 µM) treatment. Apoptosis was increased in 10 and 20 µM curcumin-treated MG-63 cells. After incubation of physically wounded cells for 24 hours, the percentage wound width increased upon curcumin exposure. Curcumin obviously decreased the expression of pJAK-2 and pSTAT-3 in MG-63 cells in a dose-dependent manner. Curcumin dose-dependently inhibited the proliferation, migration, and invasion of MG-63 cells and induced arrest of the G0/G1 phase and apoptosis by inhibiting the p-JAK2/p-STAT3 pathway. The linear correlativity between expression of p-JAK2 and STAT3 was very prominent, and both were closely associated with lung metastasis. In vivo study suggested that curcumin suppressed tumor growth through JAK2/STAT3 signaling. Conclusion Curcumin-mediated inhibition of the proliferation and migration of MG-63 cells was associated with inactivation of JAK/STAT signaling.
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Affiliation(s)
- Yuanjue Sun
- Cancer Therapy and Research Center, Shandong Provincial Hospital, Shandong University, 250021, Shandong, People's Republic of China,
| | - Liguo Liu
- Department of General Surgery, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, 200233 Shanghai, People's Republic of China
| | - Yaling Wang
- Department of Medical Oncology, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, 200233 Shanghai, People's Republic of China,
| | - Aina He
- Department of Medical Oncology, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, 200233 Shanghai, People's Republic of China,
| | - Haiyan Hu
- Department of Medical Oncology, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, 200233 Shanghai, People's Republic of China,
| | - Jianjun Zhang
- Department of Medical Oncology, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, 200233 Shanghai, People's Republic of China,
| | - Mingyong Han
- Cancer Therapy and Research Center, Shandong Provincial Hospital, Shandong University, 250021, Shandong, People's Republic of China,
| | - Yujing Huang
- Department of Medical Oncology, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, 200233 Shanghai, People's Republic of China,
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Losdyck E, Hornakova T, Springuel L, Degryse S, Gielen O, Cools J, Constantinescu SN, Flex E, Tartaglia M, Renauld JC, Knoops L. Distinct Acute Lymphoblastic Leukemia (ALL)-associated Janus Kinase 3 (JAK3) Mutants Exhibit Different Cytokine-Receptor Requirements and JAK Inhibitor Specificities. J Biol Chem 2015; 290:29022-34. [PMID: 26446793 DOI: 10.1074/jbc.m115.670224] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2015] [Indexed: 01/22/2023] Open
Abstract
JAK1 and JAK3 are recurrently mutated in acute lymphoblastic leukemia. These tyrosine kinases associate with heterodimeric cytokine receptors such as IL-7 receptor or IL-9 receptor, in which JAK1 is appended to the specific chain, and JAK3 is appended to the common gamma chain. Here, we studied the role of these receptor complexes in mediating the oncogenic activity of JAK3 mutants. Although JAK3(V674A) and the majority of other JAK3 mutants needed to bind to a functional cytokine receptor complex to constitutively activate STAT5, JAK3(L857P) was unexpectedly found to not depend on such receptor complexes for its activity, which was induced without receptor or JAK1 co-expression. Introducing a mutation in the FERM domain that abolished JAK-receptor interaction did not affect JAK3(L857P) activity, whereas it inhibited the other receptor-dependent mutants. The same cytokine receptor independence as for JAK3(L857P) was observed for homologous Leu(857) mutations of JAK1 and JAK2 and for JAK3(L875H). This different cytokine receptor requirement correlated with different functional properties in vivo and with distinct sensitivity to JAK inhibitors. Transduction of murine hematopoietic cells with JAK3(V674A) led homogenously to lymphoblastic leukemias in BALB/c mice. In contrast, transduction with JAK3(L857P) induced various types of lymphoid and myeloid leukemias. Moreover, ruxolitinib, which preferentially blocks JAK1 and JAK2, abolished the proliferation of cells transformed by the receptor-dependent JAK3(V674A), yet proved much less potent on cells expressing JAK3(L857P). These particular cells were, in contrast, more sensitive to JAK3-specific inhibitors. Altogether, our results showed that different JAK3 mutations induce constitutive activation through distinct mechanisms, pointing to specific therapeutic perspectives.
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Affiliation(s)
- Elisabeth Losdyck
- From the Ludwig Institute for Cancer Research, Brussels Branch and the de Duve Institute, Université Catholique de Louvain, 1200 Brussels, Belgium
| | - Tekla Hornakova
- From the Ludwig Institute for Cancer Research, Brussels Branch and the de Duve Institute, Université Catholique de Louvain, 1200 Brussels, Belgium
| | - Lorraine Springuel
- From the Ludwig Institute for Cancer Research, Brussels Branch and the de Duve Institute, Université Catholique de Louvain, 1200 Brussels, Belgium
| | - Sandrine Degryse
- the VIB Center for the Biology of Disease, K.U. Leuven, 3000 Leuven, Belgium, the K.U. Leuven Center for Human Genetics, K.U. Leuven, 3000 Leuven, Belgium
| | - Olga Gielen
- the VIB Center for the Biology of Disease, K.U. Leuven, 3000 Leuven, Belgium, the K.U. Leuven Center for Human Genetics, K.U. Leuven, 3000 Leuven, Belgium
| | - Jan Cools
- the VIB Center for the Biology of Disease, K.U. Leuven, 3000 Leuven, Belgium, the K.U. Leuven Center for Human Genetics, K.U. Leuven, 3000 Leuven, Belgium
| | - Stefan N Constantinescu
- From the Ludwig Institute for Cancer Research, Brussels Branch and the de Duve Institute, Université Catholique de Louvain, 1200 Brussels, Belgium
| | | | - Marco Tartaglia
- the Genetic Disorders and Rare Diseases Research Division, Ospedale Pediatrico Bambino Gesu' IRCCS, Viale di San Paolo 15, 00146 Rome, Italy
| | - Jean-Christophe Renauld
- From the Ludwig Institute for Cancer Research, Brussels Branch and the de Duve Institute, Université Catholique de Louvain, 1200 Brussels, Belgium
| | - Laurent Knoops
- From the Ludwig Institute for Cancer Research, Brussels Branch and the de Duve Institute, Université Catholique de Louvain, 1200 Brussels, Belgium, the Hematology Unit, Cliniques Universitaires Saint-Luc, 1200 Brussels, Belgium, and
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Abstract
The acquisition of growth signal self-sufficiency is 1 of the hallmarks of cancer. We previously reported that the murine interleukin-9-dependent TS1 cell line gives rise to growth factor-independent clones with constitutive activation of the Janus kinase (JAK)- signal transducer and activator of transcription (STAT) pathway. Here, we show that this transforming event results from activating mutations either in JAK1, JAK3, or in both kinases. Transient and stable expression of JAK1 and/or JAK3 mutants showed that each mutant induces STAT activation and that their coexpression further increases this activation. The proliferation of growth factor-independent TS1 clones can be efficiently blocked by JAK inhibitors such as ruxolitinib or CMP6 in short-term assays. However, resistant clones occur upon long-term culture in the presence of inhibitors. Surprisingly, resistance to CMP6 was not caused by the acquisition of secondary mutations in the adenosine triphosphate-binding pocket of the JAK mutant. Indeed, cells that originally showed a JAK1-activating mutation became resistant to inhibitors by acquiring another activating mutation in JAK3, whereas cells that originally showed a JAK3-activating mutation became resistant to inhibitors by acquiring another activating mutation in JAK1. These observations underline the cooperation between JAK1 and JAK3 mutants in T-cell transformation and represent a new mechanism of acquisition of resistance against JAK inhibitors.
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Improving treatment strategies for patients with metastatic castrate resistant prostate cancer through personalized computational modeling. Clin Exp Metastasis 2014; 31:991-9. [PMID: 25173680 DOI: 10.1007/s10585-014-9674-1] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2014] [Accepted: 08/12/2014] [Indexed: 01/26/2023]
Abstract
Metastatic castrate resistant prostate cancer (mCRPC) is responsible for the majority of prostate cancer deaths with the median survival after diagnosis being 2 years. The metastatic lesions often arise in the skeleton, and current treatment options are primarily palliative. Using guidelines set forth by the National Comprehensive Cancer Network (NCCN), the medical oncologist has a number of choices available to treat the metastases. However, the sequence of those treatments is largely dependent on the patient history, treatment response and preferences. We posit that the utilization of personalized computational models and treatment optimization algorithms based on patient specific parameters could significantly enhance the oncologist's ability to choose an optimized sequence of available therapies to maximize overall survival. In this perspective, we used an integrated team approach involving clinicians, researchers, and mathematicians, to generate an example of how computational models and genetic algorithms can be utilized to predict the response of heterogeneous mCRPCs in bone to varying sequences of standard and targeted therapies. The refinement and evolution of these powerful models will be critical for extending the overall survival of men diagnosed with mCRPC.
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Joung YH, Lim EJ, Darvin P, Chung SC, Jang JW, Do Park K, Lee HK, Kim HS, Park T, Yang YM. MSM enhances GH signaling via the Jak2/STAT5b pathway in osteoblast-like cells and osteoblast differentiation through the activation of STAT5b in MSCs. PLoS One 2012; 7:e47477. [PMID: 23071812 PMCID: PMC3469535 DOI: 10.1371/journal.pone.0047477] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2012] [Accepted: 09/17/2012] [Indexed: 01/27/2023] Open
Abstract
Methylsulfonylmethane (MSM) is a naturally occurring sulfur compound with well-known anti-oxidant properties and anti-inflammatory activities. But, its effects on bone are unknown. Growth hormone (GH) is regulator of bone growth and bone metabolism. GH activates several signaling pathways such as the Janus kinase (Jak)/signal transducers and activators of transcription (STAT) pathway, thereby regulating expression of genes including insulin-like growth factor (IGF)-1. GH exerts effects both directly and via IGF-1, which signals by activating the IGF-1 receptor (IGF-1R). In this study, we investigated the effects of MSM on the GH signaling via the Jak/STAT pathway in osteoblasts and the differentiation of primary bone marrow mesenchymal stem cells (MSCs). MSM was not toxic to osteoblastic cells and MSCs. MSM increased the expression of GH-related proteins including IGF-1R, p-IGF-1R, STAT5b, p-STAT5b, and Jak2 in osteoblastic cells and MSCs. MSM increased IGF-1R and GHR mRNA expression in osteoblastic cells. The expression of MSM-induced IGF-1R and GHR was inhibited by AG490, a Jak2 kinase inhibitor. MSM induced binding of STAT5 to the IGF-1R and increased IGF-1 and IGF-1R promoter activities. Analysis of cell extracts by immunoprecipitation and Western blot showed that MSM enhanced GH-induced activation of Jak2/STAT5b. We found that MSM and GH, separately or in combination, activated GH signaling via the Jak2/STAT5b pathway in UMR-106 cells. Using siRNA analysis, we found that STAT5b plays an essential role in GH signaling activation in C3H10T1/2 cells. Osteogenic marker genes (ALP, ON, OCN, BSP, OSX, and Runx2) were activated by MSM, and siRNA-mediated STAT5b knockdown inhibited MSM-induced expression of osteogenic markers. Furthermore, MSM increased ALP activity and the mineralization of MSCs. Taken together, these results indicated that MSM can promote osteogenic differentiation of MSCs through activation of STAT5b.
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Affiliation(s)
- Youn Hee Joung
- Department of Pathology, School of Medicine, Institute of Biomedical Science and Technology, Konkuk University, Seoul, Republic of Korea
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Albu RI, Constantinescu SN. Extracellular domain N-glycosylation controls human thrombopoietin receptor cell surface levels. Front Endocrinol (Lausanne) 2011; 2:71. [PMID: 22649382 PMCID: PMC3355985 DOI: 10.3389/fendo.2011.00071] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/13/2011] [Accepted: 10/21/2011] [Indexed: 01/13/2023] Open
Abstract
The thrombopoietin receptor (TpoR) is a type I transmembrane protein that mediates the signaling functions of thrombopoietin (Tpo) in regulating megakaryocyte differentiation, platelet formation, and hematopoietic stem cell renewal. We probed the role of each of the four extracellular domain putative N-glycosylation sites for cell surface localization and function of the receptor. Single N-glycosylation mutants at any of the four sites were able to acquire the mature N-glycosylated pattern, but exhibited a decreased Tpo-dependent JAK2-STAT response in stably transduced Ba/F3 or Ba/F3-JAK2 cell lines. The ability of JAK2 to promote cell surface localization and stability of TpoR required the first N-glycosylation site (Asn117). In contrast, the third N-glycosylation site (Asn298) decreased receptor maturation and stability. TpoR mutants lacking three N-glycosylation sites were defective in maturation, but N-glycosylation on the single remaining site could be detected by sensitivity to PNGaseF. The TpoR mutant defective in all four N-glycosylation sites was severely impaired in plasma membrane localization and was degraded by the proteasome. N-glycosylation receptor mutants are not misfolded as, once localized on the cell surface in overexpression conditions, they can bind and respond to Tpo. Our data indicate that extracellular domain N-glycosylation sites regulate in a combinatorial manner cell surface localization of TpoR. We discuss how mutations around TpoR N-glycosylation sites might contribute to inefficient receptor traffic and disease.
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Affiliation(s)
- Roxana I. Albu
- Ludwig Institute for Cancer ResearchBrussels, Belgium
- de Duve Institute, Université catholique de LouvainBrussels, Belgium
| | - Stefan N. Constantinescu
- Ludwig Institute for Cancer ResearchBrussels, Belgium
- de Duve Institute, Université catholique de LouvainBrussels, Belgium
- *Correspondence: Stefan N. Constantinescu, Ludwig Institute for Cancer Research, de Duve Institute, Université catholique de Louvain, Avenue Hippocrate 74, UCL 75-4, Brussels B-1200, Belgium. e-mail:
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Jiao B, Cheng CHK. Disrupting actions of bisphenol A and malachite green on growth hormone receptor gene expression and signal transduction in seabream. FISH PHYSIOLOGY AND BIOCHEMISTRY 2010; 36:251-261. [PMID: 20467862 DOI: 10.1007/s10695-008-9227-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/17/2008] [Accepted: 05/06/2008] [Indexed: 05/29/2023]
Abstract
Environmental estrogen could mimic natural estrogens thereby disrupting the endocrine systems of human and animals. The actions of such endocrine disruptors have been studied mainly on reproduction and development. However, estrogen could also affect the somatotropic axis via multiple targets such as growth hormone (GH). In the present study, two endocrine disruptors were chosen to investigate their effects on the expression level and signal transduction of growth hormone receptor (GHR) in fish. Using real-time PCR, it was found that exposure to both the estrogenic (bisphenol A) and anti-estrogenic (malachite green) compounds could attenuate the expression levels of GHR1 and GHR2 in black seabream (Acanthopagrus schlegeli) hepatocytes. The expression level of IGF-I, the downstream effector of GHR activation in the liver, was decreased by bisphenol A but not by malachite green. Luciferase reporter assay of the beta-casein promoter was used to monitor GHR signaling in transfected cells. In the fish liver cell line Hepa-T1, both GHR1 and GHR2 signaling were attenuated by bisphenol A and malachite green. This attenuation could only occur in the presence of estrogen receptor, indicating that these agents probably produce their actions via the estrogen receptor. Results of the present study demonstrated that estrogenic or anti-estrogenic compounds could down-regulate the somatotropic axis in fish by affecting both the gene expression and signaling of GHR. In view of the increasing prevalence of these compounds in the environment, the impact on fish growth and development both in the wild and in aquaculture would be considerable.
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Affiliation(s)
- Baowei Jiao
- Department of Biochemistry and the Environmental Science Programme, The Chinese University of Hong Kong, Shatin, NT, Hong Kong, China
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Tran GT, Pagkalos J, Tsiridis E, Narvani AA, Heliotis M, Mantalaris A, Tsiridis E. Growth hormone: does it have a therapeutic role in fracture healing? Expert Opin Investig Drugs 2010; 18:887-911. [PMID: 19480608 DOI: 10.1517/13543780902893069] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
BACKGROUND The role of growth hormone (GH) in augmenting fracture healing has been postulated for over half a century. GH has been shown to play a role in bone metabolism and this can be mediated directly or indirectly through IGF-I. OBJECTIVES The use of GH was evaluated as a possible therapeutic agent in augmenting fracture healing. METHOD A literature search was undertaken on GH and its effect on bone fracture healing primarily using MEDLINE/OVID (1950 to January 2009). Key words and phrases including 'growth hormone', 'insulin like growth factor', 'insulin like growth factor binding protein', 'insulin like growth factor receptor', 'fracture repair', 'bone healing', 'bone fracture', 'bone metabolism', 'osteoblast' and 'osteoclast' were used in different combinations. Manual searches of the bibliography of key papers were also undertaken. RESULTS Current evidence suggests a positive role of GH on fracture healing as demonstrated by in vitro studies on osteoblasts, osteoclasts and the crosstalk between the two. Animal studies have demonstrated a number of factors influencing the effect of GH in vivo such as dose, timing and method of administration. Application of this knowledge in humans is limited but clearly demonstrates a positive effect on fracture healing. Concern has been raised in the past regarding the safety profile of the pharmacological use of GH when used in critically ill patients. CONCLUSION The optimal dose and method of administration is still to be determined, and the safety profile of this novel use of GH needs to be investigated prior to establishing its widespread use as a fracture-healing agent.
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Affiliation(s)
- Gui Tong Tran
- University of Leeds School of Medicine, Academic Department of Trauma and Orthopaedics, Leeds General Infirmary, Great George Street, Leeds, UK
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Gan Y, Zhang Y, Digirolamo DJ, Jiang J, Wang X, Cao X, Zinn KR, Carbone DP, Clemens TL, Frank SJ. Deletion of IGF-I receptor (IGF-IR) in primary osteoblasts reduces GH-induced STAT5 signaling. Mol Endocrinol 2010; 24:644-56. [PMID: 20133448 DOI: 10.1210/me.2009-0357] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
GH promotes longitudinal growth and regulates multiple cellular functions in humans and animals. GH signals by binding to GH receptor (GHR) to activate the tyrosine kinase, Janus kinase 2 (JAK2), and downstream pathways including signal transducer and activator of transcription 5 (STAT5), thereby regulating expression of genes including IGF-I. GH exerts effects both directly and via IGF-I, which signals by activating the IGF-I receptor (IGF-IR). IGF-IR is a cell surface receptor that contains intrinsic tyrosine kinase activity within its intracellular domain. In this study, we examined the potential role of IGF-IR in facilitating GH-induced signal transduction, using mouse primary calvarial osteoblasts with Lox-P sites flanking both IGF-IR alleles. These cells respond to both GH and IGF-I and in vitro infection with an adenovirus that drives expression of Cre recombinase (Ad-Cre) dramatically reduces IGF-IR abundance without affecting the abundance of GHR, JAK2, STAT5, or ERK. Notably, infection with Ad-Cre, but not a control adenovirus, markedly inhibited acute GH-induced STAT5 activity (more than doubling the ED(50) and reducing the maximum activity by nearly 50%), while sparing GH-induced ERK activity, and markedly inhibited GH-induced transactivation of a STAT5-dependent luciferase reporter. The effect of Ad-Cre on GH signaling was specific, as platelet-derived growth factor-induced signaling was unaffected by Ad-Cre-mediated reduction of IGF-IR. Ad-Cre-mediated inhibition of GH signaling was reversed by adenoviral reexpression of IGF-IR, but not by infection with an adenovirus that drives expression of a hemagglutination-tagged somatostatin receptor, which drives expression of the unrelated somatostatin receptor, and Ad-Cre infection of nonfloxed osteoblasts did not affect GH signaling. Notably, infection with an adenovirus encoding a C-terminally truncated IGF-IR that lacks the tyrosine kinase domain partially rescued both acute GH-induced STAT5 activity and GH-induced IGF-I gene expression in cells in which endogenous IGF-IR was reduced. These data, in concert with our earlier findings that GH induces a GHR-JAK2-IGF-IR complex, suggest a novel function for IGF-IR. In addition to its role as a key IGF-I signal transducer, this receptor may directly facilitate acute GH signaling. The implications of these findings are discussed.
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Affiliation(s)
- Yujun Gan
- Department of Cell Biology, University of Alabama at Birmingham, Birmingham, Alabama 35294, USA
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Hornakova T, Staerk J, Royer Y, Flex E, Tartaglia M, Constantinescu SN, Knoops L, Renauld JC. Acute lymphoblastic leukemia-associated JAK1 mutants activate the Janus kinase/STAT pathway via interleukin-9 receptor alpha homodimers. J Biol Chem 2009; 284:6773-81. [PMID: 19139102 DOI: 10.1074/jbc.m807531200] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Activating mutations in JAK1 have been reported in acute lymphoblastic leukemias, but little is known about the mechanisms involved in their constitutive activation. Here, we studied the ability of JAK1 V658F and A634D to activate the Janus kinase (JAK)/STAT pathway upon ectopic expression in HEK293 cells alone or together with the other components of the interleukin-9 receptor complex (IL-9Ralpha, gammac, and JAK3). Expression of JAK1 mutants alone failed to trigger STAT activation, but co-expression of the IL-9Ralpha chain promoted JAK1 mutant phosphorylation and STAT activation. Mutation of the FERM domain of JAK1, which is critical for cytokine receptor association, or of the single tyrosine of IL-9Ralpha involved in STAT recruitment abolished this activity, indicating that JAK1 mutants need to associate with a functional IL-9Ralpha to activate STAT factors. Several lines of evidence indicated that IL-9Ralpha homodimerization was involved in this process. IL-9Ralpha variants with mutations of the JAK-interacting BOX1 region not only failed to promote JAK1 activation but also acted as dominant negative forms reverting the effect of wild-type IL-9Ralpha. Coimmunoprecipitation experiments also showed the formation of IL-9Ralpha homodimers. Interestingly, STAT activation was partially inhibited by expression of gammac, suggesting that overlapping residues are involved in IL-9Ralpha homodimerization and IL-9Ralpha/gammac heterodimerization. Co-expression of wild-type JAK3 partially reverted the inhibition by gammac, indicating that JAK3 cooperates with JAK1 mutants within the IL-9 receptor complex. Similar results were observed with IL-2Rbeta. Taken together, our results show that IL-9Ralpha and IL-2Rbeta homodimers efficiently mediate constitutive activation of ALL-associated JAK1 mutants.
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Affiliation(s)
- Tekla Hornakova
- Ludwig Institute for Cancer Research, Brussels Branch and de Duve Institute, Université Catholique de Louvain, B-1200 Brussels, Belgium
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Malka Y, Hornakova T, Royer Y, Knoops L, Renauld JC, Constantinescu SN, Henis YI. Ligand-independent homomeric and heteromeric complexes between interleukin-2 or -9 receptor subunits and the gamma chain. J Biol Chem 2008; 283:33569-77. [PMID: 18829468 DOI: 10.1074/jbc.m803125200] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Signaling via interleukin-2 (IL-2) and interleukin-9 receptors (IL-2R and IL-9R) involves heteromeric interactions between specific interleukin receptor subunits, which bind Janus kinase 1 (JAK1) and the JAK3 binding common gamma chain (gamma c). The potential existence and roles of homomeric and heteromeric complexes before ligand binding and their modulation by ligand and JAK3 are unclear. Using computerized antibody-mediated immunofluorescence co-patching of epitope-tagged receptors at the surface of live cells, we demonstrate that IL-2Rbeta, IL-9Ralpha, and gamma c each display a significant fraction of ligand-independent homomeric complexes (24-28% co-patching), whereas control co-patching levels with unrelated receptors are very low (7%). Heteromeric complex formation of IL2-Rbeta or IL-9Ralpha with gamma c is also observed in the absence of ligand (15-30%). Ligand binding increases this hetero-oligomerization 2-fold but does not affect homo-oligomerization. Co-expression of IL-2Ralpha does not affect the hetero-oligomerization of IL-2Rbeta and gamma c. Recruitment of gamma c into heterocomplexes is partly at the expense of its homo-oligomerization, suggesting that a functional role of the latter may be to keep the receptors inactive in the absence of ligand. At the same time, the preformed complexes between gamma c and IL-2Rbeta or IL-9Ralpha promote signaling by the JAK3 A572V mutant without ligand, supporting a pathophysiological role for the constitutive oligomerization in triggering ligand-independent activation of JAK3 (and perhaps other JAK mutants) mutants identified in several human cancers.
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Affiliation(s)
- Yaniv Malka
- Department of Neurobiology, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv 69978, Israel
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Crippa GE, Beloti MM, Cardoso CR, Silva JS, Rosa AL. Effect of growth hormone on in vitro osteogenesis and gene expression of human osteoblastic cells is donor-age-dependent. J Cell Biochem 2008; 104:369-76. [DOI: 10.1002/jcb.21628] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Ziros PG, Georgakopoulos T, Habeos I, Basdra EK, Papavassiliou AG. Growth hormone attenuates the transcriptional activity of Runx2 by facilitating its physical association with Stat3beta. J Bone Miner Res 2004; 19:1892-904. [PMID: 15476590 DOI: 10.1359/jbmr.040701] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/12/2003] [Revised: 05/12/2004] [Accepted: 07/07/2004] [Indexed: 12/18/2022]
Abstract
UNLABELLED We document that GH controls osteoblast function by modulating the biological activity of the osteospecific transcription factor Runx2. Evidence is provided for a physical interaction between Runx2 and Stat3beta, which is enhanced by GH and downregulates the transcriptional properties of this key osteogenic regulator. INTRODUCTION Growth hormone (GH) signals to bone either through insulin-like growth factor-1 or directly by influencing the function of osteoblasts, the bone-forming cells. This study aimed at exploring the molecular events that underlie the direct biological action of GH on osteoblastic cells, and specifically, the effects that it might exert on the function of the bone-specific transcriptional regulator Runx2. MATERIALS AND METHODS The GH-responsive human osteoblastic cell line Saos-2 was used as our experimental system. Western blot analyses were used to monitor the presence of several parameters known to be affected by GH in these cells (i.e., downregulation of GH receptor, induction of STATs, and extracellular signal-regulated kinase [ERK] mitogen-activated protein kinase [MAPK] pathways). Electrophoretic mobility shift assays were used to assess Runx2 and Stat3 binding activity on an osteoblast-specific element (OSE2) after GH treatment. A combination of yeast two-hybrid and co-immunoprecipitation assays were performed to test for the existence of a physical Runx2.Stat3beta association. Finally, co-transfection experiments were used to investigate the interplay of the two transcription factors on the activity of a p6OSE2-Luc promoter after GH stimulation. RESULTS We show that GH signaling through Stat3/ERK MAPK potentiates the DNA binding activity of Runx2 but, at the same time, restrains its transcriptional potential. Moreover, a novel physical interaction of Runx2 with transcription factor Stat3beta, which is enhanced by GH stimulation, was documented both in vitro and in vivo. Importantly, this interaction impairs the transcriptional activity of Runx2 without affecting its DNA binding capacity. CONCLUSION Our data provide the first evidence that GH modulates the transcriptional function of Runx2 in osteoblastic cells by promoting its inhibitory interaction with Stat3beta. Shedding light on such mechanisms will contribute to a better understanding of GH effects on skeletal homeostasis that may impact on decisions at the clinical level, especially in diseases affecting bone quantity and quality (e.g., osteoporosis).
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Affiliation(s)
- Panos G Ziros
- Department of Biochemistry, School of Medicine, University of Patras, Patras, Greece
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Clausen LR, Kristiansen MT, Rasmussen LM, Billestrup N, Blaabjerg O, Ledet T, Jørgensen JOL. Growth hormone receptor expression and function in pituitary adenomas. Clin Endocrinol (Oxf) 2004; 60:576-83. [PMID: 15104560 DOI: 10.1111/j.1365-2265.2004.02022.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
OBJECTIVE AND DESIGN Hypopituitarism, in particular GH deficiency, is prevalent in patients with clinically nonfunctioning pituitary adenomas (NFPAs) both before and after surgery. The factors regulating the growth of pituitary adenomas in general and residual tumour tissue in particular are not fully characterized, and the effect of GH and IGF-I on human pituitary cell proliferation has not previously been reported. In NFPA tissue from 14 patients we evaluated GH receptor (GHR) expression and signal transduction, and the effect of GH and IGF-I exposure on cell proliferation and hormone secretion in vitro. MEASUREMENTS Tissue samples from 14 NFPAs were investigated. Expression of GHR in tissue samples was assessed by reverse transcription polymerase chain reaction (RT-PCR). Six tumours were immunostained with a GHR antibody. In the cell cultures, STAT5 (signal transducer and activator of transcription 5) phosphorylation was measured by Western blot analysis as an index of GHR signalling; cell proliferation was evaluated by [H3]-thymidine incorporation and glycoprotein hormone production analysed by radioimmunoassay (RIA). RESULTS All adenomas investigated expressed the GHR, but there was no detection of STAT5 phosphorylation. Overall, GH and IGF-I administration did not significantly stimulate cell proliferation in vitro, although some individual adenomas exhibited a proliferative response to various extents. GH also did not significantly influence glycoprotein hormone secretion in vitro. CONCLUSION GH receptors are expressed in human pituitary adenoma cells but their functional role is uncertain. GH and IGF-I do not consistently influence the proliferation of cultured pituitary adenoma cells.
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Affiliation(s)
- Lene R Clausen
- Medical Department M (Endocrinology and Diabetes) and Institute of Experimental Clinical Research, Aarhus University Hospital, Aarhus, Denmark
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Kim CH, Kim YH, Kim YK, Kang BS, Lee TK, Moon SH, Park YG. IL-1beta induces and TGF-beta reduces vitamin D3-induced bone resorption in mouse calvarial bone cells. Immunol Invest 2003; 32:171-86. [PMID: 12916707 DOI: 10.1081/imm-120022977] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Bone cells produce multiple growth factors and cytokines that have effects on bone metabolism and can be incorporated into the bone matrix. The present study was designed to extend these observations by examining the interactions between transforming growth factor-beta (TGF-beta) or interleukin-1beta (IL-1beta) and bone cells in a rat long bone culture model. IL-1beta regulates several activities of the osteoblast cells derived from rat long bone explants in vitro. IL-1beta stimulated cellular proliferation and the synthesis of prostaglandin E2 and plasminogen activator activity in the cultured cells in a dose-dependent manner. TGF-B is present in the bone matrix and potentially can be released during bone resorption. TGF-beta reduced basal bone resorption and inhibited vitamin D3 [1,25(OH)2D3]-induced bone resorption in rat long bone cells. These studies support the role of IL-1beta in the pathological modulation of bone cell metabolism, with regard to implication in the pathogenesis of osteoporosis by IL-1beta, and that TGF-beta is positively inhibiting the bone resorption.
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Affiliation(s)
- Cheorl-Ho Kim
- National Research Laboratory for Glycobiology (NRLG), Korean Ministry of Science and Technology, Kyungju City, Kyungbuk, Korea.
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16
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Morales O, Faulds MH, Lindgren UJ, Haldosén LA. 1Alpha,25-dihydroxyvitamin D3 inhibits GH-induced expression of SOCS-3 and CIS and prolongs growth hormone signaling via the Janus kinase (JAK2)/signal transducers and activators of transcription (STAT5) system in osteoblast-like cells. J Biol Chem 2002; 277:34879-84. [PMID: 12107179 DOI: 10.1074/jbc.m204819200] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Growth hormone (GH) and 1alpha,25-dihydroxyvitamin D(3) (1,25-(OH)(2)D(3)) are regulators of bone growth and bone metabolism. In target cells, GH activates several signaling pathways, among them the Janus kinase (JAK)/signal transducers and activators of transcription (STAT) pathway. GH mainly activates JAK2 and STAT5a and b. The effects of 1,25-(OH)(2)D(3) are mediated via a nuclear receptor, the vitamin D receptor, which, when bound by 1,25-(OH)(2)D(3), activates the transcription of target genes. In earlier studies (Morel, G., Chavassieux, P., Barenton, B., Dubois, P. M., Meunier, P. J., and Boivin, G. (1993) Cell Tissue Res. 273, 279-286) synergistic interaction between 1,25-(OH)(2)D(3) and GH regarding expression of osteoblastic markers has been described. The UMR 106 cell line is a rat osteosarcoma cell line with osteoblast-like properties. We have recently shown (Morales, O., Lindgren, U., and Haldosen, L. A. (2000) J. Bone Miner. Res. 15, 2284-2290) that UMR 106 cells express a GH-responsive JAK2/STAT5 signaling system. These cells also express the vitamin D receptor and respond to 1,25-(OH)(2)D(3). In the present study we have investigated whether 1,25-(OH)(2)D(3) influences GH signaling via the JAK2/STAT5 pathway in UMR 106 cells. We found that 1,25-(OH)(2)D(3) prolonged GH signaling via the JAK2/STAT5 pathway. Pretreatment of cells with 1,25-(OH)(2)D(3) was also necessary in order to detect GH-induced STAT5 transcriptional response. Furthermore, the pretreatment of cells with 1,25-(OH)(2)D(3) rendered to the cells the capacity to respond to repetitive GH-stimulation. In UMR 106 cells, GH induced the expression of the JAK/STAT negative regulatory proteins SOCS-3 and CIS. Interestingly, pretreatment with 1,25-(OH)(2)D(3) inhibited GH-induced expression of these proteins. From these results we propose that 1,25-(OH)(2)D(3) has an inhibitory effect on negative regulatory pathways acting on JAK2 and/or STAT5 in UMR 106 cells and that this, in all or partly, explains the effects of 1,25-(OH)(2)D(3) on GH-signaling via the JAK/STAT pathway.
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Affiliation(s)
- Orlando Morales
- Department of Orthopedic Surgery, Karolinska Institutet, Huddinge Hospital, S-141 86 Huddinge, Sweden
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17
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Park S, Kim H, Kim SJ. Stimulation of ERK2 by taurine with enhanced alkaline phosphatase activity and collagen synthesis in osteoblast-like UMR-106 cells. Biochem Pharmacol 2001; 62:1107-11. [PMID: 11597579 DOI: 10.1016/s0006-2952(01)00741-9] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Taurine is present in a variety of tissues and exhibits many important physiological functions in the cell. Even though its functions are well documented in many tissues, its actions on bone cells are largely unknown. Considering a recent finding that taurine is present in the bone, we wished to determine if taurine could have any effects on osteoblast cells. Taurine (10 mM) stimulated alkaline phosphatase activity as well as collagen synthesis. Taurine also stimulated tyrosine phosphorylation of a number of cellular proteins including a 42-kDa protein. The 42-kDa protein was identified as extracellular signal regulated protein kinase 2 (ERK2). A mitogen-activated protein kinase kinase (MEK) inhibitor blocked the taurine-stimulated alkaline phosphatase activity and collagen synthesis. These results suggest that taurine could regulate osteoblast metabolism via ERK2 activation.
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Affiliation(s)
- S Park
- Department of Pharmacology, School of Dentistry, Kyung-Hee University, 130-701, Seoul, Korea
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