scholarly journals The Activation of the Phosphotyrosine Phosphatase η (r-PTPη) Is Responsible for the Somatostatin Inhibition of PC Cl3 Thyroid Cell Proliferation

2001 ◽  
Vol 15 (10) ◽  
pp. 1838-1852 ◽  
Author(s):  
Tullio Florio ◽  
Sara Arena ◽  
Stefano Thellung ◽  
Rodolfo Iuliano ◽  
Alessandro Corsaro ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Phosphatase Activity ◽  
Time Course ◽  
Kinase Inhibitor ◽  
Specific Activity ◽  
Somatostatin Receptor ◽  
Thyroid Cell ◽  
Phosphotyrosine Phosphatase ◽  
Thyroid Cells ◽  
Antiproliferative Effects

Abstract The aim of this study was the characterization of the intracellular effectors of the antiproliferative activity of somatostatin in PC Cl3 thyroid cells. Somatostatin inhibited PC Cl3 cell proliferation through the activation of a membrane phosphotyrosine phosphatase. Conversely, PC Cl3 cells stably expressing the v-mos oncogene (PC mos) were completely insensitive to the somatostatin antiproliferative effects since somatostatin was unable to stimulate a phosphotyrosine phosphatase activity. In PC mos cells basal phosphotyrosine phosphatase activity was also reduced, suggesting that the expression of a specific phosphotyrosine phosphatase was impaired in these transformed cells. We suggested that this phosphotyrosine phosphatase could be r-PTPη whose expression was abolished in the PC mos cells. To directly prove the involvement of r-PTPη in somatostatin’s effect, we stably transfected this phosphatase in PC mos cells. This new cell line (PC mos/PTPη) recovered somatostatin’s ability to inhibit cell proliferation, showing dose-dependence and time course similar to those observed in PC Cl3 cells. Conversely, the transfection of a catalytically inactive mutant of r-PTPη did not restore the antiproliferative effects of somatostatin. PC mos/PTPη cells showed a high basal phosphotyrosine phosphatase activity which, similarly to PC Cl3 cells, was further increased after somatostatin treatment. The specificity of the role of r-PTPη in somatostatin receptor signal transduction was demonstrated by measuring its specific activity after somatostatin treatment in an immunocomplex assay. Somatostatin highly increased r-PTPη activity in PCCl3 and PC mos/PTPη (+300%, P < 0.01) but not in PCmos cells. Conversely, no differences in somatostatin-stimulated SHP-2 activity, (∼ +50%, P < 0.05), were observed among all the cell lines. The activation of r-PTPη by somatostatin caused, acting downstream of MAPK kinase, an inhibition of insulin-induced ERK1/2 activation with the subsequent blockade of the phosphorylation, ubiquitination, and proteasome degradation of the cyclin-dependent kinase inhibitor p27kip1. Ultimately, high levels of p27kip1 lead to cell proliferation arrest. In conclusion, somatostatin inhibition of PC Cl3 cell proliferation requires the activation of r-PTPη which, through the inhibition of MAPK activity, causes the stabilization of the cell cycle inhibitor p27kip1.

scholarly journals Oncogene Transformation of PC Cl3 Clonal Thyroid Cell Line Induces an Autonomous Pattern of Proliferation That Correlates with a Loss of Basal and Stimulated Phosphotyrosine Phosphatase Activity*

Endocrinology ◽  
1997 ◽  
Vol 138 (9) ◽  
pp. 3756-3763 ◽  
Author(s):  
Tullio Florio ◽  
Antonella Scorziello ◽  
Stefano Thellung ◽  
Salvatore Salzano ◽  
Maria Teresa Berlingieri ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Phosphatase Activity ◽  
Cell Lines ◽  
Proliferative Activity ◽  
Tyrosine Phosphatase ◽  
Contact Inhibition ◽  
Phosphotyrosine Phosphatase ◽  
Thyroid Cells ◽  
Transformed Cell ◽  
Transformed Cell Lines

Abstract The effects of the stable expression of E1A and/or middle T oncogenes on the proliferative activity of PC Cl3 normal thyroid cells are reported. The proliferation of PC Cl3 cells is mainly regulated by insulin and TSH in a stimulatory way and by somatostatin in an inhibitory fashion. The transformed cell lines, named PC Py and PC E1A Py, show an autonomous pattern of proliferation. The blockade of phosphotyrosine phosphatase activity with vanadate increased the proliferation rate of PC Cl3 under basal and stimulated conditions and completely prevented the inhibitory activity of somatostatin, suggesting that in PC Cl3 cells, a tonic tyrosine phosphatase activity regulates basal and stimulated proliferation, and that a somatostatin-dependent increase in this activity may represent a cytostatic signal. Conversely, in both PC Py and PC E1A Py, vanadate did not modify basal and stimulated proliferation. We analyzed tyrosine phosphatase activity in the different cell lines basally and under conditions leading to the arrest of cell proliferation: confluence (contact inhibition), growth factor deprivation (starvation), and somatostatin treatment. Under basal conditions, tyrosine phosphatase activity was significantly lower in PC Py and PC E1APy cell lines than that in the normal cells. The inhibition of the proliferation induced by contact inhibition or somatostatin treatment was accompanied by an increase in tyrosine phosphatase activity only in PC Cl3 cells. The reduction in tyrosine phosphatase activity in PC E1APy cells correlated with a significant reduction in the expression of R-PTPη, a tyrosine phosphatase cloned from PC Cl3 cells. Conversely, the expression of another receptor-like PTP, PTPμ, was unchanged. Thus, PTPη may be a candidate to mediate inhibitory signals (i.e. activation of somatostatin receptors or cell to cell contact) on the proliferative activity of PC Cl3 cells, and the reduction of its expression in the transformed cell lines may lead to an alteration in the control of cell proliferation.

scholarly journals Somatostatin Inhibits PC Cl3 Thyroid Cell Proliferation through the Modulation of Phosphotyrosine Phosphatase Activity

1996 ◽  
Vol 271 (11) ◽  
pp. 6129-6136 ◽  
Author(s):  
Tullio Florio ◽  
Antonella Scorziello ◽  
Morena Fattore ◽  
Vito D'Alto ◽  
Salvatore Salzano ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Phosphatase Activity ◽  
Thyroid Cell ◽  
Phosphotyrosine Phosphatase

scholarly journals TSH-induced differentiated functions correlate with enhancement of phosphotyrosine phosphatase activity in thyroid cells. Effect of phorbol 12-myristate 13-acetate

2001 ◽  
Vol 169 (3) ◽  
pp. 603-611 ◽  
Author(s):  
E Petitfrere ◽  
E Huet ◽  
H Sartelet ◽  
L Martiny ◽  
O Legue ◽  
...  
Keyword(s):  
Phosphatase Activity ◽  
Specific Inhibitor ◽  
Inhibitory Effect ◽  
Dependent Manner ◽  
Phosphotyrosine Phosphatase ◽  
Thyroid Cells ◽  
Kinase C ◽  
Gf 109203X ◽  
Dose Dependent ◽  
Ptpase Activity

TSH-treated pig thyroid cells reorganize into follicle-like structures and exhibit differentiated functions. TSH also induces a phosphotyrosine phosphatase (PTPase) activity evaluated by phosphorylated substrate hydrolysis. Incubation of thyrocytes with various concentrations of 8-bromo-cyclic AMP or forskolin induces an increase of PTPase activity in a dose-dependent manner. During the culture period, adenylyl cyclase sensitivity, protein binding iodine and PTPase activity progressively increase from the first to the fourth day of the culture. Chronic treatment with phorbol 12-myristate 13-acetate (PMA) significantly inhibits PTPase activity during the first 24 h following PMA addition. GF 109203X, a specific inhibitor of protein kinase C, abolishes the inhibitory effect of PMA. Electrophoresis of membrane extracts allowed us to demonstrate a phosphatase activity at 111 kDa (p111). Vanadate inhibits this activity, indicating that p111 is a PTPase. This p111 is significantly reduced in PMA-treated cells. These data suggest that PTPase activity evidenced at 111 kDa is correlated with a differentiated state of primary cultured pig thyroid cells induced by TSH.

scholarly journals Identification of microRNAs that Mediate Thyroid Cell Growth Induced by TSH

2012 ◽  
Vol 26 (3) ◽  
pp. 493-501 ◽  
Author(s):  
Takeshi Akama ◽  
Mariko Sue ◽  
Akira Kawashima ◽  
Huhehasi Wu ◽  
Kazunari Tanigawa ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cell Proliferation ◽  
Protein Kinase ◽  
Cell Growth ◽  
Protein Kinase A ◽  
Target Genes ◽  
Endocrine Function ◽  
Thyroid Cell ◽  
Thyroid Cells ◽  
Kinase A

Abstract TSH is a major regulator of thyroid cell growth and endocrine function. It is known that cAMP and phosphatidylinositol 3-kinase (PI3K) are responsible for mediating the action of TSH. Activation of these signals results in the induction of a series of transcription factors and cell cycle regulating proteins, which induce cell proliferation. In addition to such canonical transcriptional regulation, it was recently shown that microRNA (miRNA or miR) constitutes another key mechanism for the regulation of gene expression. However, whether TSH action is mediated by miRNA in the thyroid is unknown. In this study, we have performed miRNA microarray analysis and demonstrated that TSH significantly decreases expression of 47 miRNA in thyroid cells. Among these, we have shown, using their specific agonists, that overexpression of miR-16 and miR-195 suppressed cell cycle progression and DNA synthesis that was induced by TSH. In silico analysis predicted that Mapk8, Ccne1, and Cdc6, the expression of which was up-regulated by TSH, are potential target genes for these miRNA, and overexpression of miR-16 and miR-195 suppressed expression of these target genes. The decrease of miR-16 and miR-195 expression by TSH was reproduced by forskolin and N6,2′-O-dibutyryladenosine cAMP and reversed by the protein kinase A inhibitor H89 and the PI3K inhibitor LY294002. These results suggest that TSH activates cAMP/protein kinase A and PI3K cascades to decrease miR-16 and miR-195, which induce Mapk8, Ccne1, and Cdc6 to activate cell proliferation.

scholarly journals Sorafenib Treatment and Modulation of the Sphingolipid Pathway Affect Proliferation and Viability of Hepatocellular Carcinoma In Vitro

2020 ◽  
Vol 21 (7) ◽  
pp. 2409
Author(s):  
Katja Jakobi ◽  
Sandra Beyer ◽  
Alexander Koch ◽  
Dominique Thomas ◽  
Stephanie Schwalm ◽  
...  
Keyword(s):  
Hepatocellular Carcinoma ◽  
Cell Proliferation ◽  
Kinase Inhibitor ◽  
Fumonisin B1 ◽  
Bioactive Metabolites ◽  
Sorafenib Treatment ◽  
Antiproliferative Effects ◽  
Dismal Prognosis ◽  
In Vitro Effects

Hepatocellular carcinoma (HCC) shows a remarkable heterogeneity and is recognized as a chemoresistant tumor with dismal prognosis. In previous studies, we observed significant alterations in the serum sphingolipids of patients with HCC. This study aimed to investigate the in vitro effects of sorafenib, which is the most widely used systemic HCC medication, on the sphingolipid pathway as well as the effects of inhibiting the sphingolipid pathway in HCC. Huh7.5 and HepG2 cells were stimulated with sorafenib, and inhibitors of the sphingolipid pathway and cell proliferation, viability, and concentrations of bioactive metabolites were assessed. We observed a significant downregulation of cell proliferation and viability and a simultaneous upregulation of dihydroceramides upon sorafenib stimulation. Interestingly, fumonisin B1 (FB1) and the general sphingosine kinase inhibitor SKI II were able to inhibit cell proliferation more prominently in HepG2 and Huh7.5 cells, whereas there were no consistent effects on the formation of dihydroceramides, thus implying an involvement of distinct metabolic pathways. In conclusion, our study demonstrates a significant downregulation of HCC proliferation upon sorafenib, FB1, and SKI II treatment, whereas it seems they exert antiproliferative effects independently from sphingolipids. Certainly, further data would be required to elucidate the potential of FB1 and SKI II as putative novel therapeutic targets in HCC.

scholarly journals The somatostatin receptor SSTR1 is coupled to phosphotyrosine phosphatase activity in CHO-K1 cells.

1994 ◽  
Vol 8 (10) ◽  
pp. 1289-1297
Author(s):  
T Florio ◽  
C Rim ◽  
R E Hershberger ◽  
M Loda ◽  
P J Stork
Keyword(s):  
Phosphatase Activity ◽  
Somatostatin Receptor ◽  
Phosphotyrosine Phosphatase

Characterization of thyroid-stimulating immunoglobulin-induced cyclic AMP accumulation in the rat thyroid cell strain FRTL-5: potentiation by forskolin and calibration against reference preparations of thyrotrophin

1985 ◽  
Vol 105 (1) ◽  
pp. 7-15 ◽  
Author(s):  
S. P. Bidey ◽  
J. M. Emmerson ◽  
N. J. Marshall ◽  
R. P. Ekins
Keyword(s):  
Cyclic Amp ◽  
Time Course ◽  
Disease Patient ◽  
Fixed Dose ◽  
Thyroid Cell ◽  
Thyroid Cells ◽  
Response Parameter ◽  
Cyclic Amp Accumulation ◽  
Long Acting ◽  
Rat Thyroid

ABSTRACT A clonal strain of rat thyroid cells (FRTL-5) has been used to investigate the biological activity of a Research Standard preparation of long-acting thyroid stimulator (LATS-B). Using the accumulation of intracellular cyclic AMP as a response parameter, significant stimulation was attained at a LATS-B dose of 0·75 mu./ml. The inter-bioassay coefficient of variation in response to a fixed dose of LATS-B (1·25 mu./ml) was 20·5%, as determined using eight sequential subcultures. Cells cultured directly from frozen stocks responded to both bovine TSH and LATS-B in a manner indistinguishable from cells subjected to regular subculturing. Cyclic AMP responses to incremental doses of LATS-B were potentiated after the inclusion of a low dose of forskolin (0·1 μmol/l). However, forskolin addition had no effect on the time-course of LATS-B-stimulated cyclic AMP accumulation, half-maximal responses being attained after 60 min in either the presence or absence of the diterpene. In the presence of 0·1 μmol forskolin/l, intracellular cyclic AMP responses to LATS-B were demonstrably parallel with those to human TSH (Second International Reference Preparation, 80/558), whilst parallel incremental cyclic AMP responses were also observed in respect of TSH and serial dilutions of a potent thyroid-stimulating immunoglobulin (TSIg) preparation, indicating that for this particular Graves' disease patient, TSIg bioactivity may be expressed in terms of a convenient and reproducible standard, as TSH microunit equivalents. J. Endocr. (1985) 105, 7–15

Augmentation of the cytotoxicity of ibandronate by y-27632, a rho kinase inhibitor, in prostate cancer cells.

2012 ◽  
Vol 30 (15_suppl) ◽  
pp. e15104-e15104
Author(s):  
Alper Ata ◽  
Ata Ozcimen ◽  
Hakan Kurt ◽  
Nalan Tiftik ◽  
Ali Arican ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Time Course ◽  
Kinase Inhibitors ◽  
Kinase Inhibitor ◽  
Mevalonate Pathway ◽  
Rho Kinase ◽  
Prostate Cell ◽  
Farnesyl Transferase ◽  
Cell Index ◽  
Prostate Cancers

e15104 Background: Bisphosphonates, which have been used for the treatment of breast and prostate cancers (Epplen et al., 2011) inhibit mevalonate pathway that results in the reduction of Ras prenylation, which eventually inhibits tumor growth (Luckman et al., 1998). Rho/Rho kinase signaling has a fundamental role in cancer cell proliferation, migration and metastasis (Vega et al., 2008) Therefore, in this study, we aimed to investigate effects of Y-27632, which inhibits Rho-kinase, ibandronate, which inhibits farnesyl transferase and their combination on cell proliferation in prostate cell lines, PC-3. Methods: The adherent prostate cell line, PC-3 (ATCC) was grown in RPMI-1640 supplemented with 10 % fetal bovine serum, 1 % L-glutamine, 1 % penicillin (10.000U/ml) and streptomycin (10.000 mg/ml) in a humidified atmosphere of 5 % CO2 at 37oC for confluency. The cells were seeded in the wells of E-plates (24,000 cells/well) that allowed a real-time-monitoring of the cell index reflected cell growth and proliferation (xCELLigence, Roche). The cell index was evaluated at the different points of time (post-treatment 12, 24, 36, 48, 60 and 72 h) in the groups of ibandronate, Y-27632, the combination and time-course control. Results: Ibandronate (10-100 mM), Y-27632 (50-100 mM) markedly decreased cell index. The combination of Y-27632 with ibandronate resulted in potentiation of cytotoxicity in PC-3 cells. Conclusions: Rho kinase inhibitors, biphosphonates and their combination may be beneficial for the treatment of prostate cell cancers.

scholarly journals Wnt-Independent Role of β-Catenin in Thyroid Cell Proliferation and Differentiation

2014 ◽  
Vol 28 (5) ◽  
pp. 681-695 ◽  
Author(s):  
Ana Sastre-Perona ◽  
Pilar Santisteban
Keyword(s):  
Cell Proliferation ◽  
Transcription Factor ◽  
Protein Kinase ◽  
Transcriptional Activity ◽  
Nuclear Accumulation ◽  
Cell Physiology ◽  
Thyroid Cell ◽  
Thyroid Cells ◽  
Cell Proliferation And Differentiation ◽  
Proliferation And Differentiation

Abstract The Wnt/β-catenin pathway has been associated with thyroid cell growth and tumorigenesis. However, little is known regarding its involvement in the response to the key regulators of thyroid cell proliferation and differentiation. Here we show that TSH and IGF-1 increase β-catenin nuclear accumulation and its transcriptional activity in differentiated thyroid cells. This effect takes place in a Wnt-independent manner because TSH and IGF-1, through the activation of protein kinase A and protein kinase B/Akt, phosphorylate β-catenin at S552 and S675, which results in β-catenin release from E-cadherin at the adherens junctions. Nuclear β-catenin regulates thyroid cell proliferation, because its silencing or the overexpression of a dominant-negative form of T-cell factor 4 resulted in reduced levels of cyclin D1 and DNA synthesis. Furthermore, the β-catenin silencing markedly reduced the expression of Pax8, the main transcription factor involved in epithelial thyroid cell differentiation. Finally, we observed that β-catenin physically interacts with the transcription factor Pax8, increasing its transcriptional activity on the sodium iodide symporter (NIS) gene, a critical gene required for thyroid cell physiology. Taken together, our findings show that β-catenin plays a not yet described role in thyroid function including a functional interaction with Pax8.

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