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 Iodide symporter gene expression in normal and transformed rat thyroid cells

1999 ◽  
pp. 447-451 ◽  
Author(s):  
F Trapasso ◽  
R Iuliano ◽  
E Chiefari ◽  
F Arturi ◽  
A Stella ◽  
...  
Keyword(s):  
Gene Expression ◽  
Cell Lines ◽  
Inhibitory Effect ◽  
Mrna Levels ◽  
Iodide Uptake ◽  
Thyroid Cells ◽  
Transformed Cell ◽  
Nis Gene ◽  
Rat Thyroid ◽  
Transformed Cell Lines

OBJECTIVE: Decrease or loss of the Na+/I- symporter (NIS) activity profoundly affects the suitability of the use of radioiodine to detect or treat metastatic thyroid tissues. The aim of our study was to verify whether specific oncogene abnormalities were responsible for the alteration in NIS activity in thyroid cells. DESIGN AND METHODS: Expression of the NIS gene was investigated by Northern blot analysis in normal and in some oncogene-transformed cell lines with different degrees of malignancy which had lost the iodide uptake ability. RESULTS: NIS gene expression was up-regulated by TSH in a dose-dependent and time-dependent way in normal PC Cl 3 cells. The same effect was observed by activating the cAMP-dependent pathway by forskolin. Conversely, insulin and 12-O-tetradecanoylphorbol-13-acetate (TPA) showed a partial inhibitory effect on NIS gene expression. The oncogene-transformed cell lines PC v-erbA, PC HaMSV, PC v-raf, and PC E1A cells showed reduced NIS mRNA levels compared with the normal PC Cl 3 cells. Conversely, an almost complete absence of NIS gene expression was found in PC RET/PTC, PC KiMSV, PC p53(143ala), and PC PyMLV cell lines. CONCLUSIONS: Our data show that oncogene activation could play a role in affecting the iodide uptake ability in thyroid tumoral cells; different mechanisms are involved in the oncogene-dependent loss of NIS activity in transformed thyroid cells.

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 Effect of tunicamycin on cell growth and morphology of nontransformed and transformed cell lines.

1979 ◽  
Vol 43 (7) ◽  
pp. 1553-1561 ◽  
Author(s):  
Kenji KOHNO ◽  
Akiyoshi HIRAGUN ◽  
Hiromi MITSUI ◽  
Akira TAKATSUKI ◽  
Gakuzo TAMURA
Keyword(s):  
Cell Growth ◽  
Cell Lines ◽  
Transformed Cell ◽  
Transformed Cell Lines

scholarly journals G3BP1 promotes stress-induced RNA granule interactions to preserve polyadenylated mRNA

2015 ◽  
Vol 209 (1) ◽  
pp. 73-84 ◽  
Author(s):  
Anaïs Aulas ◽  
Guillaume Caron ◽  
Christos G. Gkogkas ◽  
Nguyen-Vi Mohamed ◽  
Laurie Destroismaisons ◽  
...  
Keyword(s):  
Normal Stress ◽  
Cell Lines ◽  
Translational Repression ◽  
Primary Neurons ◽  
Processing Bodies ◽  
Transformed Cell ◽  
Upstream Regulator ◽  
Functional Consequences ◽  
Transformed Cell Lines ◽  
Polyadenylated Mrna

G3BP1, a target of TDP-43, is required for normal stress granule (SG) assembly, but the functional consequences of failed SG assembly remain unknown. Here, using both transformed cell lines and primary neurons, we investigated the functional impact of this disruption in SG dynamics. While stress-induced translational repression and recruitment of key SG proteins was undisturbed, depletion of G3BP1 or its upstream regulator TDP-43 disturbed normal interactions between SGs and processing bodies (PBs). This was concomitant with decreased SG size, reduced SG–PB docking, and impaired preservation of polyadenylated mRNA. Reintroduction of G3BP1 alone was sufficient to rescue all of these phenotypes, indicating that G3BP1 is essential for normal SG–PB interactions and SG function.

The preferential cytotoxicity of reovirus for certain transformed cell lines

1977 ◽  
Vol 54 (4) ◽  
pp. 307-315 ◽  
Author(s):  
G. Hashiro ◽  
P. C. Loh ◽  
Jenny T. Yau
Keyword(s):  
Cell Lines ◽  
Transformed Cell ◽  
Transformed Cell Lines
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