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G Villone

Publications and source records attributed to G Villone.

14 recordsLinked to original sources
PubMed2000

Association between the expression of E1A oncogene and increased sensitivity to growth inhibition induced by sustained levels of cAMP in rat thyroid cells.

OBJECTIVE: The aim of this study was to investigate: (i) whether a persistent increase of cAMP interferes with the proliferation of transformed thyroid cells, and (ii) whether the degree of malignancy is correlated with the sensitivity to a transient and/or sustained increase in intracellular cAMP levels. DESIGN AND METHODS: To address these questions we used thyroid cell lines transformed with E1A oncogene from adenoviruses 5 (PC E1A cell line) or 2 (PC HE4 cell line), or infected with the polyoma murine leukemia virus (PC PyMLV cell line) carrying the middle T gene of the polyoma virus, or, finally, expressing both E1A and PyMLV. These cell lines present various degrees of malignancy: PC EIA and PC HE4 cells are not tumorigenic; PC PyMLV cells induce non-invasive tumors after a long latency period; and PC EIA+PyMLV cells are highly tumorigenic. RESULTS AND CONCLUSIONS: Thyroid cell proliferation required the transient increase of intracellular cAMP levels, while persistent elevation of cAMP blocked the proliferation of normal thyroid PC Cl 3 cells and of PC Cl 3 cells transformed by a variety of different oncogenes. In addition, sustained levels of cAMP induced apoptosis in cells carrying the adenovirus EIA oncogene, but not in cells transformed with other oncogenes or in the wild-type PC Cl 3 cells. Furthermore, middle T gene of the polyoma virus seemed to afford protection only from apoptosis induced by cAMP when middle T is present in thyroid cells along with the E1A gene.

Adenovirus E1A Proteins↗
PubMed1999

Endogenous insulin-like growth factors regulate the proliferation of TSH-independent mutants derived from FRTL5 cells.

TSH-independent mutant clones (M cells) derived from FRTL5 cells, proliferate vigorously in the absence of TSH. The growth of M cells is stimulated by IGF-I in a dose-dependent fashion, but it is not influenced by TSH. Sm1.2, an antibody against IGF-I cross-reacting with IGF-II, significantly decreases basal DNA synthesis in the M cells. Binding of 125I-IGF-I to M cells is significantly lower than that to FRTL5 cells. M cells produce in their culture medium IGF-like peptides which appear to influence their basal DNA synthesis and the availability of type I receptors to bind exogenous IGF-I.

Animals↗
PubMed1997

[Not Available].

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Bioethics↗
PubMed1997

Sustained versus transient cyclic AMP intracellular levels: effect on thyrotropin-dependent growth of thyroid cells.

Cyclic AMP (cAMP) is the second messenger that stimulates growth and differentiation of thyroid cells, which are dependent upon thyrotropin for the initiation of the cell cycle. Treatment of thyroid cells with phosphodiesterase inhibitors, such as 1-methyl-3-isobutylxanthine (IBMX), RO-20-1724, or aminophylline, induces persistent levels of cAMP and blocks cell proliferation. IBMX-treated cells are arrested at the G1-S border, but removal of the drug allows cell growth to resume. The inhibiting effect of IBMX is dose dependent, and the phase of the cell cycle is irrelevant. These data indicate that prolonged and steady accumulation of cAMP blocks the cell cycle in thyroid cells.

1-Methyl-3-isobutylxanthine↗
PubMed1994

Expression of the soluble lectin L-14 gene is induced by TSH in thyroid cells and suppressed by retinoic acid in transformed neural cells.

Expression of the soluble lectin L-14 is low in normal and very high in transformed thyroid cells. We show that L-14 gene expression is transiently induced upon thyrotropin stimulation of normal quiescent FRTL-5 rat thyroid cells. Permanent activation of L-14 gene expression is obtained in the same cells infected with a wild-type and a temperature sensitive mutant of Kirsten murine sarcoma virus, both at the permissive and non permissive temperature for transformation. We also find that L-14 mRNA is undetectable in rat brain but is abundant in rat oligodendrocytes precursors transformed by polyoma middle T oncogene. Retinoic acid treatment of these transformed cells leads to acquisition of a differentiated phenotype accompanied by a 30-fold decrease of L-14 mRNA levels. Removal of retinoic acid restores both the transformed undifferentiated phenotype and high L-14 expression. Taken together these results indicate that growth stimulation and induction of cell differentiation are accompanied by strong modulation of L-14 gene expression.

Animals↗
PubMed1994

[AIDS in Naples in 1800. 12 cases of Kaposi sarcoma described by Tommaso de Amicis].

In 1882, Tommaso de Amicis, dermatologist and venereologist at the University of Naples, Italy, published a description of twelve cases of Kaposi's sarcoma. This article is the second report about the above-mentioned disease after the first description of five cases by Moritz Kaposi ten years earlier. The publication by De Amicis was organized as a collection of case reports followed by a section containing general considerations about the etiopathogenesis, pathology, diagnosis and therapy of Kaposi's sarcoma. Ten cases are typical of the so-called 'classic' form of the disease, that has a peculiar indolent chronic course, while two out of the twelve cases strongly resemble the clinical form of Kaposi's sarcoma currently recognized as that associated with the acquired immunodeficiency syndrome (AIDS). The nature of Kaposi's sarcoma is still being debated, but current evidence suggests that it is a viral-associated, if not viral-induced, tumor and its relationship with AIDS is that of an opportunistic disease. Thus, the presence of the clinical form of AIDS-related Kaposi's sarcoma can be used as a marker of the presence of sporadic cases of AIDS much earlier than its pandemic diffusion.

AIDS-Related Opportunistic Infections↗
PubMed1993

In the thyroid cells proliferation, differentiated and metabolic functions are under the control of different steps of the cyclic AMP cascade.

In the course of studies to elucidate the complex network of interactions controlling FRTL5 cell proliferation, thyroid stimulating hormone (TSH)-independent mutants (M cells), have been obtained from FRTL5 cells by chemical mutagenesis. In the present studies, the role of TSH on the proliferation and on differentiated and metabolic functions in these mutant cells have been investigated and compared to their response to insulin-like growth factor I (IGF-I). The addition of IGF-I to M cells leads to normal stimulation of DNA synthesis. However, inspite of the fact that mutant cells display normal TSH receptors, TSH is unable to stimulate the proliferation of the M cells. Nevertheless, TSH is able to increase intracellular levels of cAMP leading to regulation of TSH function in the M cells. On the other hand, TSH does not influence iodide transport and actin filaments depolimerization in these cells. However, aminoacid transport, stimulated in wild-type FRTL5 cells by both TSH and IGFs, is under the control of IGFs but not of TSH in the mutant cells. Neither TSH or IGF-I modified the expression of c-fos proto-oncogene in the M cells, probably because of high constitutive expression. These data suggest that a crucial signalling step(s) required for TSH induced mitogenesis is impaired in the M cells, and that this signalling step is not required for IGF-I induced mitogenesis.

Aminoisobutyric Acids↗
PubMed1992

Transfected insulin-like growth factor II modulates the mitogenic response of rat thyrocytes in culture.

Rat thyroid cells (FRTL5), transfected with the sequence coding for rat insulin-like growth factor II (IGF-II) presented mRNA specific for the transfected IGF-II in most of the clones obtained (Tr clones). Tr7 and Tr12 cells maintained their ability to respond to the mitogenic effect of thyrotropin (TSH), while either exogenous IGF-I or IGF-II or insulin failed to stimulate their proliferation. In the absence of exogenous mitogens the Tr7 and Tr12 clones vigorously incorporated [3H]thymidine into DNA. This activity was significantly inhibited by sm1.2, a monoclonal antibody against rat IGF-II. Tr7 and Tr12 clones possess type I IGF receptors, known to mediate the mitogenic effect of IGF-II, with affinity similar to those present on the membrane of the parental cells but with reduced capacity. Finally, media conditioned by Tr7 and Tr12 increase basal thymidine incorporation in quiescent FRTL5 cells and amplify that induced by TSH. Endogenous IGFs may play an important role in the regulation of thyroid cell proliferation by modulating the mitogenic effect of TSH and by supporting TSH-independent growth.

Animals↗
PubMed1990

The tissue-specific pathways regulating cell proliferation are inherited independently in somatic hybrid between thyroid and liver cells.

Thyroid stimulating hormone (TSH) and insulin-like growth factors type 1 (IGF-I) regulate the proliferation and differentiation of cultured thyroid cells but not of cultured liver cells. We have examined the influence of TSH and IGF-I on the metabolic functions and proliferation of somatic hybrids obtained by fusing rat thyroid cells (FRTL5) with rat liver cells (BRL). While IGF-I is able to stimulate the proliferation of the hybrid cells (TxL) TSH fails to induce their growth. However, the hybrid TxL cells have surface TSH receptors with normal ligand characteristics. The addition of TSH to TxL cells led to typical enhancement of cAMP production and depolymerization of actin filaments. Yet, TSH failed to stimulate iodine uptake in the hybrid cells. Interestingly, iodine inhibited TxL proliferation induced by IGF-I but not by serum. It is concluded that the hybrid TxL cells inherited from the parental thyroid cells several important differentiated traits including mitogenic pathways induced and used by IGF-I, functional TSH receptors, and sensitivity to the inhibitory action of iodine.

Animals↗
PubMed1989

Insulin and insulin-like growth factor I (IGF I) stimulate phosphorylation of a Mr 175,000 cytoskeleton-associated protein in intact FRTL5 cells.

FRTL5 rat thyroid cells possess separate high affinity receptors for insulin and insulin-like growth factor I (IGF I) that undergo beta-subunit phosphorylation upon interaction with the specific ligand. Phosphorylation is rapid and dose-dependent and occurs primarily on tyrosine residues. Within 2 min, both insulin and IGF I also give rise to a Mr 175,000 phosphoprotein (pp175) that can be immunoprecipitated by anti-phosphotyrosine antibody (alpha-Tyr(P]. Phosphorylation of pp175 occurs on serine and threonine as well as tyrosine residues. When FRTL5 cells are solubilized with 1% Triton X-100, alpha-Tyr(P) immunoprecipitates phosphorylated insulin and IGF I receptors but little pp175 from the Triton-soluble fraction. After treatment of the Triton-insoluble portion with 1% sodium dodecyl sulfate at 100 degrees C, pp175 can be identified by immunoprecipitation with alpha-Tyr(P). The fraction of FRTL5 cells that remains after extraction of an attached monolayer with 1% Triton for 5 min at 22 degrees C contains most of the cytoskeleton and also nuclei. Extraction of this 32P-labeled cytoskeleton preparation with sodium dodecyl sulfate followed by alpha-Tyr(P) immunoprecipitation results in almost complete recovery of the pp175 content of the cells. When a nuclear fraction was prepared from FRTL5 cells by differential centrifugation, pp175 was not found in the nuclear pellet from labeled cells, but greater than 80% of pp175 was recovered in the supernatant. We conclude that pp175 is a common substrate for insulin and IGF I receptor kinases which, in FRTL5 cells, is associated with the cytoskeleton. It is suggested that phosphorylation of proteins associated with cytoskeletal elements could be involved in insulin and IGF I action in cells.

Animals↗
PubMed1989

Iodine inhibits the proliferation of rat thyroid cells in culture.

We have explored the mechanisms whereby iodine inhibits thyroid growth using as models both the FRTL5 line of rat thyroid follicular cells that require TSH for growth and the M12 line of mutant cells that grow in the absence of TSH. Between 0.01-1.0 mM, NaI produced a dose-dependent inhibition of TSH stimulation of [3H]thymidine incorporation and replication in FRTL5 cells as well as spontaneous growth in M12 cells. Iodide also inhibited the cAMP-dependent growth of FRTL5 cells induced by forskolin and (Bu)2cAMP, as well as the cAMP-independent mitogenesis induced by insulin-like growth factor-I. The effect of iodide to inhibit both TSH- and insulin-like growth factor-I-stimulated growth in FRTL5 cells was abolished by concomitant culture with methimazole, and no iodide inhibition of growth was observed in L6 myoblasts and BRL 30E hepatocytes. Exposure of cells to iodide under conditions that resulted in inhibition of TSH-stimulated growth did not significantly alter the ability of TSH to increase the intracellular cAMP concentration, nor did iodide alter two responses to TSH in FRTL5 cells that depend upon an increase in cAMP concentration: down-regulation of TSH receptor and cytoskeletal reorganization. We conclude that iodide exerts its inhibitory action on the growth of thyroid cells at multiple loci related to both the cAMP-dependent and cAMP-independent pathways of mitogenic regulation.

Animals↗
PubMed1988

Demonstration of the production and physiological role of insulin-like growth factor II in rat thyroid follicular cells in culture.

Insulin-like growth factors (IGFs) are potent mitogens for FRTL5 rat thyroid follicular cells. IGFs also synergize the independent mitogenic effects of thyrotropin-stimulating hormone (TSH) and other agents that increase intracellular AMP concentration. We examined whether FRTL5 cells and M12 cells, a TSH-independent mutant cell line derived therefrom, secrete IGF that regulates the growth of rat thyroid follicular cells. Immunoreactive IGF-II, but not IGF-I, was found in media conditioned by FRTL5 cells; media from M12 cells contained four- to fivefold higher concentrations. Medium conditioned by FRTL5 and M12 both stimulated [3H]thymidine incorporation in FRTL5 and amplified the mitogenic effects of TSH. M12-conditioned medium was more potent than FRTL5-conditioned medium. Sm-1.2, a monoclonal antibody that recognizes IGF-I and IGF-II but not insulin, inhibited basal DNA synthesis in FRTL5 and M12 cells and the mitogenic effects in FRTL5 of agents that are synergized by IGF, such as TSH, forskolin, Bt2cAMP, and Graves'-IgG. Sm-1.2 did not inhibit the mitogenic response to insulin. Thus, rat insulin-like growth factor II (rIGF-II) is an autocrine growth factor that regulates FRTL5 growth, in part by amplifying the mitogenic response to TSH. Results with M12 cells raise the possibility that endogenous rIGF-II may partially mediate the TSH-independent growth of these cells.

Animals↗
PubMed1987

The FRTL-5 thyroid cell strain as a model for studies on thyroid cell growth.

Thyroid cell proliferation has been studied using an in vitro system of rat thyroid follicular cell strain (FRTL-5). While growing in continuous culture, this strain is still differentiated and non-tumourigenic. Both advantages and limitations in the use of such system for studies of thyroid cell growth should be considered. Some obvious limitations should be considered, such as the species (rat) from which FRTL-5 cells were originated, their long-term growth outside the animals, the presence of a chronic TSH stimulation. On the other hand, several advantages as the growth in hormonally and chemically defined media, their dependence upon TSH in the medium, their genetic homogeneity and their widespread use in many laboratories render the FRTL-5 strain a useful experimental tool. Studies on cell proliferation and mechanism of action of hormones, growth factors and human autoimmune IgG have been and are being performed, with the assumption that FRTL-5 cells are the in vitro equivalent of thyroid follicular cells.

Animals↗