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Biomedical subjects

A Fusco

Publications and source records attributed to A Fusco.

At least 199 records · Page 11Linked to original sources
PubMed1993

Mitogenic and dedifferentiating effect of the K-fgf/hst oncogene on rat thyroid PC clone 3 epithelial cells.

Transfection of rat thyroid differentiated epithelial cells, PC clone 3, with the K-fgf/hst oncogene results in alleviation of thyrotropin dependency for growth and suppression of the differentiated phenotype without the acquisition of the fully transformed phenotype. An autocrine mechanism is responsible for these effects, since the proliferation of PC clone 3 cells, induced by K-FGF-conditioned medium, is blocked by anti-K-FGF-specific antibodies. Moreover, addition of K-FGF-conditioned medium inhibits the thyroid differentiated functions. Also, such other members of the fibroblast growth factor family as basic and acidic fibroblast growth factor are able to induce thyroid cell growth and to block expression of the differentiated functions.

Animals↗
PubMed1993

The Adenovirus E1A gene blocks the differentiation of a thyroid epithelial cell line, however the neoplastic phenotype is achieved only after cooperation with other oncogenes.

The PC Cl 3 cell line is a well characterized epithelial thyroid cell line of Fischer rat origin. This cell line has the peculiarity of retaining in vitro the typical markers of thyroid differentiation (i.e. thyroglobulin synthesis and secretion, iodide uptake and dependence on TSH for growth). The PC Cl 3 cells have been transfected with the E1A gene of Adenovirus 5. The E1A transfected cells, PC E1A, partially lost the dependency on TSH for growth and completely lost the ability to trap iodide and synthesize thyroglobulin; however they did not acquire the typical markers of the neoplastic phenotype. A highly malignant phenotype was achieved after infection of the PC E1A cells with retroviruses carrying the v-raf, v-abl and polyoma virus middle T oncogenes. In contrast, the PC E1A cells transfected with the E1B gene of Adenovirus were not tumorigenic at all, and those infected with retroviruses carrying oncogenes of the ras family displayed a very weak tumorigenic phenotype.

Adenovirus E1A Proteins↗
PubMed1993

The TRK and RET tyrosine kinase oncogenes cooperate with ras in the neoplastic transformation of a rat thyroid epithelial cell line.

We have recently reported that about 50% of papillary thyroid carcinomas harbor an activated TRK or RET oncogene. Two retroviral vectors containing the activated TRK or RET/PTC oncogene have been used to infect a differentiated rat thyroid epithelial cell line, namely the PC Clone 3 cell line. Upon infection with the TRK virus, the PC Clone 3 cells lost only the ability to trap iodide and to express the thyroperoxidase gene. Conversely, when infected with the PTC virus, the PC Clone 3 cells completely lost all of their differentiated functions. However, both the PC-TRK and PC-PTC cell lines were unable to grow in soft agar, and they were not tumorigenic when injected into nude mice. A completely undifferentiated and malignant phenotype was obtained by the cooperation between the TRK or RET and the viral Ha-ras or Ki-ras oncogenes.

Animals↗
PubMed1992

Characterization of an inversion on the long arm of chromosome 10 juxtaposing D10S170 and RET and creating the oncogenic sequence RET/PTC.

RET/PTC is a transforming sequence created by the fusion of the tyrosine kinase domain of the RET protooncogene with the 5' end of the locus D10S170 designated by probe H4 and is frequently found activated in human papillary thyroid carcinomas. RET and D10S170 have been mapped to contiguous regions of the long arm of chromosome 10: q11.2 and q21, respectively. To identify the mechanism leading to the generation of the oncogenic sequence RET/PTC, a combined cytogenetic and molecular analysis of several cases of papillary thyroid carcinomas was done. In four cases the results indicated that these tumors had RET/PTC activation and a paracentric inversion of the long arm of chromosome 10, inv(10)(q11.2q21), with breakpoints coincident with the regions where RET and D10S170 are located. Therefore, a chromosome 10q inversion provides the structural basis for the D10S170-RET fusion that forms the hybrid transforming sequence RET/PTC.

Blotting, Southern↗
PubMed1992

Detection of RET oncogene activation in human papillary thyroid carcinomas by in situ hybridisation.

We have recently reported the activation of a new oncogene in human papillary thyroid carcinomas. This oncogene, named PTC, is a novel rearranged version of the ret proto-oncogene. In fact PTC is the product of the fusion of the tyrosine kinase domain of the ret proto-oncogene with the 5'-terminal region of another gene that we have named H4. The ret proto-oncogene shows a pattern of expression restricted to neuroendocrine tissue. Its fusion with H4 allows the expression of the activated form in thyroid papillary carcinomas. Therefore the detection of ret transcripts is a tool to investigate ret activation in thyroid neoplasms. Here we show the detection by in situ hybridisation, of activated ret transcripts in human thyroid papillary neoplasms that were positive for PTC activation by Southern blot analysis. We did not find any ret transcripts in papillary carcinomas negative for PTC activation, nor in normal thyroid and in non-papillary thyroid neoplasias.

3T3 Cells↗
PubMed1992

Multiple mechanisms of interference between transformation and differentiation in thyroid cells.

Transformation of the thyroid cell line FRTL-5 results in loss or reduction of differentiation as measured by the expression of thyroglobulin and thyroperoxidase, two proteins whose genes are exclusively expressed in thyroid follicular cells. The biochemical mechanisms leading to this phenomenon were investigated in three cell lines obtained by transformation of FRTL-5 cells with Ki-ras, Ha-ras, and polyomavirus middle-T oncogenes. With the ras oncogenes, transformation leads to undetectable expression of the thyroglobulin and thyroperoxidase genes. However, the mechanisms responsible for the extinction of the differentiated phenotype seem to be different for the two ras oncogenes. In Ki-ras-transformed cells, the mRNA encoding TTF-1, a transcription factor controlling thyroglobulin and thyroperoxidase gene expression, is severely reduced. On the contrary, nearly wild-type levels of TTF-1 mRNA are detected in Ha-ras-transformed cells. Furthermore, overexpression of TTF-1 can activate transcription of the thyroglobulin promoter in Ki-ras-transformed cells, whereas it has no effect on thyroglobulin transcription in the Ha-ras-transformed line. Expression of polyoma middle-T antigen in thyroid cells leads to only a reduction of differentiation and does not severely affect either the activity or the amount of TTF-1. Another thyroid cell-specific transcription factor, TTF-2, is more sensitive to transformation, since it disappears in all three transformed lines, and probably contributes to the reduced expression of the differentiated phenotype.

Animals↗
PubMed1992

[Description of cell line established from human thyroid papillary cancer and secreting human chorionic gonadotropin hormone].

One of the difficulties in characterization of the oncogenes involved in thyroid carcinogenesis is the production of cell lines. Arising from a poorly differentiated thyroid papillary carcinoma we have established a cell line synthesizing the thyroglobulin and human chorionic gonadotropin (alpha and beta subunits) (HCG) hormones. These cells will allow research of the oncogenes involved or potentially involved in thyroid papillary carcinomas and evaluation of the role of the autocrine secretion of HCG.

Carcinoma, Papillary↗
PubMed1992

Identification of the product of two oncogenic rearranged forms of the RET proto-oncogene in papillary thyroid carcinomas.

In papillary thyroid carcinomas, we have identified two tumor-specific rearrangements of the RET proto-oncogene leading to the formation of different transforming fusion products sharing the tyrosine kinase (tk) domain of the proto-oncogene and designated ptc-1 and ptc-2. We have analysed ptc-1 and ptc-2 products by immunoprecipitation with specific anti-RET antibodies followed by immunoblotting with the same reagent or with antibodies specific for phosphotyrosine (P-tyr) residues. The anti-RET antibodies were reactive with 64-kDa (p64ptc-1) and 81-kDa (p81ptc-2) proteins from lysates of ptc-1 and ptc-2 transformed cells, respectively, and identified two proteins of 140 kDa and 160 kDa from extracts of SK-N-SH, a neuroblastoma cell line previously shown to express two differently glycosylated forms of the normal RET product. The anti P-tyr antibodies, while detecting the same p64ptc-1 and p81ptc-2 proteins from ptc-1 and ptc-2 extracts, did not show any specific band in the neuroblastoma lysates. An additional set of experiments led us to conclude that, whereas the normal product of the RET proto-oncogene is a membrane-associated receptor-like molecule not intrinsically phosphorylated on tyrosine, both oncogenic forms of RET, ptc-1 and ptc-2, are constitutively phosphorylated on tyrosine, display an 'in vitro' autophosphorylation activity, are translocated from the membrane to the cytoplasm and are apparently unaffected by protein kinase C modulation.

3T3 Cells↗
PubMed1992

Increased expression of the negative growth factor, galactoside-binding protein, gene in transformed thyroid cells and in human thyroid carcinomas.

Murine beta-galactoside-binding protein has been shown to be a cell growth regulatory molecule and a cytostatic factor. We analysed the beta-galactoside-binding protein gene expression in a thyroid cell system including two normal cell lines (FRTL-5 and PC Cl 3) and the same cells transfected by several oncogenes that induce different degrees of malignancy and differentiation. We show that beta-galactoside-binding protein mRNA levels correlate with the expression of the malignant phenotype. Run-on experiments suggest that a transcriptional effect accounts at least in part for such a difference. We also show that the beta-galactoside-binding protein gene expression is increased in most human papillary thyroid carcinomas compared with normal thyroid.

Adenovirus E1A Proteins↗
PubMed1991

Altered expression of the two naturally occurring human insulin receptor variants in isolated adipocytes of non-insulin-dependent diabetes mellitus patients.

The human insulin receptor gene is expressed in two variant isoforms which differ by the absence (HIR-A) or presence (HIR-B) of 12 amino acids in the COOH-terminus of the extracellular alpha-subunit as a consequence of alternative splicing of exon 11. Expression of the two variant isoforms is regulated in a tissue-specific manner. In this study, we have measured the levels of the two receptor variants in isolated adipocytes from 10 non-insulin-dependent diabetes mellitus (NIDDM) and 11 normal subjects using an immunological assay, based on the ability of a human anti-receptor autoantibody to discriminate between HIR-A and HIR-B. Results indicate that levels of HIR-B variant are increased in NIDDM patients.

3T3 Cells↗
PubMed1991

Comparison of multiple forms of the high mobility group I proteins in rodent and human cells. Identification of the human high mobility group I-C protein.

The class I of the high mobility group (HMG) proteins is formed by phosphoproteins which are associated with AT-rich DNA sequences in the nucleus. Three HMGI proteins have previously been described in proliferating rodent cells (HMG Y, HMG I and HMGI-C). All three proteins exhibit microheterogeneity. The microheterogeneity of mouse HMG Y has been investigated in detail and shown to be due to phosphorylation of the protein which is sensitive to alkaline-phosphatase treatment. HMG I is similarly modified. Human cells have up to now only been found to contain HMG Y and HMG I. A search for the third protein, HMGI-C, in human cells was carried out and the protein was found in a hepatoma cell line, but not in normal or transformed T-cells. This HMGI-C protein was found to be modified by phosphorylation, part of which was found to be phosphatase insensitive. An unexpected additional finding in this study was that human cells contain two HMG17 proteins which differ in their N-terminal primary sequences.

Alkaline Phosphatase↗
PubMed1991

Refined localization to contiguous regions on chromosome 10q of the two genes (H4 and RET) that form the oncogenic sequence PTC.

In this report we confirm the localization of the human RET proto-oncogene to chromosome 10q11.2, both by Southern blot analysis of a panel of human-rodent somatic cell hybrids and by in situ hybridization on human metaphase chromosomes. Previously, we had assigned to the same chromosome region the gene termed H4. In about 25% of papillary thyroid carcinomas, this gene was shown to rearrange with RET to give rise to the transforming sequence PTC. The analysis of different cell hybrids containing subfragments of chromosome 10, in conjunction with pulse field gel electrophoresis, established that H4 is mapped distally to RET at a distance not less than 280 kb. These findings suggest that intrachromosomal rearrangements are responsible for PTC activation in papillary thyroid carcinomas.

Carcinoma, Papillary↗
PubMed1990

Thyrotropin receptor gene expression in oncogene-transfected rat thyroid cells: correlation between transformation, loss of thyrotropin-dependent growth, and loss of thyrotropin receptor gene expression.

Rat FRTL-5 and PC-Cl-3 thyroid cells are continuously cultured, clonal lines which require thyrotropin to grow and function. Both can be efficiently transformed when infected with RNA or DNA viruses carrying oncogenes or when directly transfected with activated oncogenes. Transformation, assayed by the appearance of cell growth in agar and by tumorigenicity in syngeneic rats or nude mice, is associated with the loss of thyrotropin-dependent cell division and thyrotropin-regulated functions such as thyroglobulin synthesis. In 16 clones of FRTL-5 or PC-Cl-3 cells transformed with different oncogenes, we show that loss of thyrotropin-dependent growth and function correlates with the loss of thyrotropin receptor gene expression, measured with a rat thyrotropin receptor cDNA probe.

Animals↗
PubMed1990

PTC is a novel rearranged form of the ret proto-oncogene and is frequently detected in vivo in human thyroid papillary carcinomas.

We recently detected a novel activated oncogene by transfection analysis on NIH 3T3 cells in five out of 20 primary human thyroid papillary carcinomas and in the available lymph node metastases. We designated this transforming gene PTC (for papillary thyroid carcinoma). Here we describe the molecular cloning and sequencing of the gene. The new oncogene resulted from the rearrangement of an unknown amino-terminal sequence to the tyrosine kinase domain of the ret proto-oncogene. This gene rearrangement was detected in all of the transfectants and in all of the original tumor DNAs, but not in normal DNA of the same patients, thus indicating that this genetic lesion occurred in vivo and is specific to somatic tumors. Moreover, the transcript coded for by the fused gene was detected in an additional PTC-positive human papillary carcinoma for which mRNA was available.

Amino Acid Sequence↗
PubMed1990

The ret proto-oncogene is consistently expressed in human pheochromocytomas and thyroid medullary carcinomas.

We have recently reported the identification of a new oncogene, named PTC, frequently activated in human thyroid papillary carcinomas. This gene is a novel rearranged form of the ret proto-oncogene and we have shown that this rearrangement occurred in vivo as a tumor-specific somatic event. In an effort to further examine the role of this oncogene in human malignancies, we have investigated the expression of the ret oncogene in a number of human tumors. We consistently detected expression of normal-sized transcripts of the ret proto-oncogene in human pheochromocytomas and in human medullary thyroid carcinomas (MTC), both of familial and sporadic type. Moreover, we showed that ret mRNA levels were increased following (Bu)2cAMP-induced differentiation of a human MTC cell line (TT). Since the ret gene has been mapped on chromosome 10, close to the gene which predisposes patients to the MEN2A syndrome, we suggest that this region of chromosome 10 might be involved in the proliferative and differentiative patterns of these neuroectodermal tissues.

Adrenal Gland Neoplasms↗
PubMed1990

Identification of serum proteins, thyroglobulin and antithyroid antibodies in the fluid of thyroid cysts.

Fluid from fourteen thyroid cysts has been submitted to electrophoretic and immunochemical procedures in order to describe the biochemical structure of the fluid. Two patterns have been identified: a pattern showing a composition similar to that of normal serum ("serum-like"); thyroglobulin concentration is low, IgG are sometimes above normal and hTg-Abs are frequently detectable. A second pattern shows instead, a picture in which serum protein fractions are largely denatured and not identifiable ("denatured"); thyroglobulin concentration has been found markedly increased. It is suggested that in "serum like" the formation of the cysts occurs in the interstitium, whereas in the "denatured" type cyst the hemorrhagic necrosis appears to be the consequence of a massive damage of the follicular tissue.

Adolescent↗