scholarly journals Activation of the erythropoietin receptor by the Friend spleen focus- forming virus gp55 glycoprotein induces constitutive protein tyrosine phosphorylation

Blood ◽  
1992 ◽  
Vol 80 (12) ◽  
pp. 3070-3078 ◽  
Author(s):  
MO Showers ◽  
JF Moreau ◽  
D Linnekin ◽  
B Druker ◽  
AD D'Andrea
Keyword(s):  
Growth Factor ◽  
Tyrosine Kinase ◽  
Tyrosine Phosphorylation ◽  
Cell Lines ◽  
Kinase Activity ◽  
Parental Cell ◽  
Erythropoietin Receptor ◽  
Parental Cell Line ◽  
Tyrosine Kinase Activity ◽  
Murine Cell

Abstract The erythropoietin receptor (EPO-R) can be activated to signal cell growth by binding either EPO or gp55, the Friend spleen focus-forming virus (SFFV) glycoprotein. EPO binding induces tyrosine kinase activity and rapid tyrosine phosphorylation of several cellular substrates. To test for gp55-induced tyrosine kinase activity, we performed immunoblots on two murine cell lines that stably express EPO-R and gp55. Stimulation of the parental cell line, Ba/F3, with murine interleukin-3 (IL-3) resulted in rapid, dose-dependent tyrosine phosphorylation of a 97-Kd substrate. Stimulation with IL-3 or EPO of the Ba/F3 cells expressing the recombinant EPO-R (Ba/F3-EPO-R) resulted in tyrosine phosphorylation of the same p97 substrate. These latter cells, when transformed to growth factor-independence by the Friend gp55 glycoprotein, exhibited constitutive tyrosine phosphorylation of the 97-Kd substrate. Other growth factor-independent Ba/F3 subclones, transformed with either the oncoprotein, v-abl, or with a constitutively activated EPO-R, also had constitutive phosphorylation of a 97-Kd substrate. In CTLL-2-EPO-R cells, a T-lymphocyte line stably transfected with the EPO-R, the 97-Kd substrate was tyrosine- phosphorylated in response to IL-2 or EPO. The 97-Kd protein was constitutively phosphorylated in CTLL-2-EPO-R-gp55 cells. In conclusion, a 97-Kd protein found in two murine cell lines is tyrosine-phosphorylated in response to multiple growth factors and viral oncoproteins, and appears to be a central phosphoprotein in signal transduction.

scholarly journals Activation of the erythropoietin receptor by the Friend spleen focus- forming virus gp55 glycoprotein induces constitutive protein tyrosine phosphorylation

Blood ◽  
1992 ◽  
Vol 80 (12) ◽  
pp. 3070-3078 ◽  
Author(s):  
MO Showers ◽  
JF Moreau ◽  
D Linnekin ◽  
B Druker ◽  
AD D'Andrea
Keyword(s):  
Growth Factor ◽  
Tyrosine Kinase ◽  
Tyrosine Phosphorylation ◽  
Cell Lines ◽  
Kinase Activity ◽  
Parental Cell ◽  
Erythropoietin Receptor ◽  
Parental Cell Line ◽  
Tyrosine Kinase Activity ◽  
Murine Cell

The erythropoietin receptor (EPO-R) can be activated to signal cell growth by binding either EPO or gp55, the Friend spleen focus-forming virus (SFFV) glycoprotein. EPO binding induces tyrosine kinase activity and rapid tyrosine phosphorylation of several cellular substrates. To test for gp55-induced tyrosine kinase activity, we performed immunoblots on two murine cell lines that stably express EPO-R and gp55. Stimulation of the parental cell line, Ba/F3, with murine interleukin-3 (IL-3) resulted in rapid, dose-dependent tyrosine phosphorylation of a 97-Kd substrate. Stimulation with IL-3 or EPO of the Ba/F3 cells expressing the recombinant EPO-R (Ba/F3-EPO-R) resulted in tyrosine phosphorylation of the same p97 substrate. These latter cells, when transformed to growth factor-independence by the Friend gp55 glycoprotein, exhibited constitutive tyrosine phosphorylation of the 97-Kd substrate. Other growth factor-independent Ba/F3 subclones, transformed with either the oncoprotein, v-abl, or with a constitutively activated EPO-R, also had constitutive phosphorylation of a 97-Kd substrate. In CTLL-2-EPO-R cells, a T-lymphocyte line stably transfected with the EPO-R, the 97-Kd substrate was tyrosine- phosphorylated in response to IL-2 or EPO. The 97-Kd protein was constitutively phosphorylated in CTLL-2-EPO-R-gp55 cells. In conclusion, a 97-Kd protein found in two murine cell lines is tyrosine-phosphorylated in response to multiple growth factors and viral oncoproteins, and appears to be a central phosphoprotein in signal transduction.

Inhibition by 5′-methylthioadenosine of cell growth and tyrosine kinase activity stimulated by fibroblast growth factor receptor in human gliomas

1995 ◽  
Vol 83 (4) ◽  
pp. 690-697 ◽  
Author(s):  
Katsuya Miyaji ◽  
Eiichi Tani ◽  
Atsuhisa Nakano ◽  
Hideyasu Ikemoto ◽  
Keizo Kaba
Keyword(s):  
Growth Factor ◽  
Cell Growth ◽  
Tyrosine Kinase ◽  
Tyrosine Phosphorylation ◽  
Protein Tyrosine Kinase ◽  
Kinase Activity ◽  
Glioma Cells ◽  
Protein Tyrosine Phosphorylation ◽  
Tyrosine Kinase Activity ◽  
Protein Tyrosine

✓ Stimulation of three human glioma cell lines with basic fibroblast growth factor (bFGF) led to the enhancement of cell growth and the rapid tyrosine phosphorylation of cellular proteins, including major substrates of 90 kD. A methyltransferase inhibitor, 5′-methylthioadenosine (MTA), inhibited dose dependently the bFGF-stimulated cell growth and protein tyrosine phosphorylation in glioma cells by blocking both receptor autophosphorylation and substrate phosphorylation, as shown by immunoblotting with antiphosphotyrosine antibodies and cross-linking bFGF to receptors. The antiproliferative activity of MTA correlated quantitatively with its potency as an inhibitor of bFGF-stimulated protein tyrosine kinase activity. The methyltransferase inhibitor MTA had no effect on either epidermal growth factor— or platelet-derived growth factor—stimulated protein tyrosine phosphorylation in glioma cells, but inhibited specifically bFGF-stimulated protein tyrosine kinase activity. The concentration of MTA required for inhibition of protein methylation correlated well with the concentration required for inhibition of bFGF-stimulated cell growth and protein tyrosine phosphorylation. Because MTA had no effect on numbers and dissociation constants of high- and low-affinity bFGF receptors, the inhibition of bFGF-stimulated bFGF receptor tyrosine kinase activity is not likely to be the result of a reduction in bFGF receptor and bFGF binding capacity. In fact, MTA delayed and reduced the internalization and nuclear translocation of bFGF, and the internalized bFGF was submitted to a limited proteolysis that converted it to lower molecular peptides whose presence remained for at least 22 hours. The effect of MTA on bFGF-stimulated tyrosine phosphorylation was immediate and readily reversible.

The Effect of EGFR-Related Tyrosine Kinase Activity Inhibition on the Growth and Invasion Mechanisms of Prostate Carcinoma Cell Lines

2003 ◽  
Vol 18 (2) ◽  
pp. 139-146 ◽  
Author(s):  
A. Ünlü ◽  
R.E. Leake
Keyword(s):  
Prostate Cancer ◽  
Growth Factor ◽  
Tyrosine Kinase ◽  
Cell Lines ◽  
Kinase Activity ◽  
Cell Types ◽  
Tyrosine Kinase Activity ◽  
Matrigel Invasion ◽  
Pc3 Cells ◽  
Epidermal Growth

Increased urokinase plasminogen activator (uPA) levels and epidermal growth factor receptor (EGFR)-related tyrosine kinase activity are associated with poor prognosis in several cancers. We studied the effect of epidermal growth factor (EGF) and a specific inhibitor of EGFR, ZM252868, on the growth and invasiveness of the prostate cancer cell lines PC3 and DU145. PC3 cell growth was stimulated by exogenous EGF but DU145 cell growth was not. EGFR-specific tyrosine kinase inhibitor significantly inhibited the growth of both cell types. EGF increased uPA protein level and uPA activity in both cell types. EGF stimulation also resulted in increased uPAR transcript in both cell lines. uPA production and activity were suppressed by the inhibitor to well below the levels in control cells. Matrigel invasion of PC3 cells was increased by EGF. ZM252868 also reversed the EGF-stimulated matrigel invasion by PC3 cells. Our results indicate that EGF is a potent stimulative agent for both growth and invasion in prostate cancer cells, and that targeting the EGFR function inhibits not only tumor growth but also invasiveness.

The Effect of Insulin-Like Growth Factor 1 on Waldenstrom Macroglobulinemia

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 4994-4994
Author(s):  
Molly R. Melhem ◽  
Aldo M. Roccaro ◽  
Mena Farag ◽  
Abdel kareem Azab ◽  
Hai T. Ngo ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Growth Factor ◽  
Tyrosine Kinase ◽  
Cell Lines ◽  
Healthy Donor ◽  
Kinase Activity ◽  
Mononuclear Cells ◽  
Tyrosine Kinase Activity ◽  
Constitutive Activation

Abstract Background: Waldenstrom’s Macroglobulinemia (WM) is an incurable lymphoplasmacytic lymphoma with limited options of therapy. Insulin-like growth factor 1 (IGF1) is a polypeptide hormone that has been shown to have a proactive role in many cancer cell types, including multiple myeloma and solid tumor cells. We evaluated the role of IGF1 in WM. Methods: WM cell lines (BCWM1 and WSU-WM) and IgM secreting low-grade lymphoma cell lines (MEC1, RL) were used. Bone marrow-derived primary CD19+ cells and bone marrow stromal cells (BMSC) were obtained from patients with WM after informed consent. The small molecule IGF-1R inhibitor II (Calbiochem) and the inhibitory antibody αIR3 (Calbiochem) were used. Cytotoxicity and DNA synthesis were measured by MTT assay and thymidine uptake assay, respectively. Cell signaling and apoptotic pathways were determined by Western Blot. Cell cycle and receptor analysis was obtained through flow cytometry. IGF1 levels were measured by ELISA. Receptor tyrosine kinase activity was evaluated in WM cell lines using the Luminex-microbeads-based assay. Results: We demonstrated that the IGF1 receptor (IGF1R) was expressed on WM primary patients and normal CD19+ control B cells, while IGF1 levels of serum and bone marrow samples in both patient and healthy donor samples were similar, suggesting a possible constitutive activation of the pathway downstream of IGF1R in WM and independent of receptor activity or cytokine levels. Surface IGF1R was expressed on BCWM1 cells, in serum-starved conditions, while, it was internalized with the addition of FBS that includes IGF-1. Finally, we also showed that IGF1 induces the activation of IGF1R as demonstrated by the induction of related tyrosine kinase activity. To demonstrate the protective effect of IGF1 on WM cells, IGF1 was added to serum starved BCWM1 cells, and we found it rescued nearly 100% of the cells from apoptosis in concentrations as low as 25ng/ml. The effect of IGF1R inhibitor on WM cells has been investigated and found that it blocked migration, induced cytotoxicity and decreased cell proliferation; without any effect on healthy donor peripheral blood mononuclear cells. Furthermore, the inhibitor decreased the tyrosine kinase activity of IGF1R, overcoming its initial activation in the presence of IGF1. Conclusion: IGF1 plays a complex role in WM cells with no evidence of constitutive activation of the receptor itself or higher levels of cytokine in WM marrow samples, indicating that activation of this pathway is downstream of IGF1R. Inhibition of IGF1R by a specific small molecule or antibody inhibitor led to a significant decrease in proliferation, survival, and migration in WM cells, but not in control mononuclear cells. These studies provide the framework to investigate the role of IGF1R inhibitors in clinical trials in WM.

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