The IGF-I axis in thyroid carcinoma

Insulin like-growth factor I (IGF-I) has been involved in the pathogenesis of a variety of human neoplasia due to the mitogenic and anti-apoptotic properties of its cognate receptor. In human thyroid carcinomas, we have previously documented an increased immunoreactivity of both IGF-I and the IGF-I receptor (IGF-I R) associated with up regulation of IGF-I mRNA . Immunoreactivity of IGF-I and cognate receptor positively correlated with tumor diameter and wide intrathyroidal extension but not with patient's gender and age or with the stage of the tumors and the occurrence of limph node metastases. Most experimental studies indicate that the effects of IGF-I on target cells are regulated in a complex fashion and depend on the simultaneous occurrence of IGF-IR and the binding proteins.

Helium-Neon laser irradiation of hepatocytes can trigger increase of the mitochondrial membrane potential and can stimulate c-fos expression in a Ca2+-dependent manner

BACKGROUND AND OBJECTIVE

To gain some insight into the photostimulation of isolated hepatocytes irradiated with Helium-Neon (He-Ne) laser light certain biochemical events were studied with respect to two mechanisms: i) the direct light dependent activation of certain biochemical events investigated in intact cells and isolated mitochondria, ii) the indirect stimulation of processes per se light independent.

STUDY DESIGNS/MATERIALS AND METHODS

Irradiation of either isolated hepatocytes or isolated rat liver mitochondria was carried out with He-Ne laser (wavelength, 632.8 nm; fluence, 0.24 J cm-2; fluence rate, 12 mW cm-2). Changes in mitochondrial membrane potential in isolated hepatocytes were monitored using the cationic probe safranine. The c-fos expression was studied by Northern blot and immunoblot analysis.

RESULTS

As a result of irradiation, increase of the mitochondrial membrane potential was found to occur in irradiated hepatocytes both in the presence or in the absence of CaCl2. The hyperpolarization of the mitochondrial membrane is assumed to cause an increase in mitochondrial Ca2+ uptake that was measured in isolated mitochondria. Finally, an increase in c-fos expression was found in irradiated hepatocytes when incubated in the presence of CaCl2.

CONCLUSION

This paper gives additional information on the mechanism by which He-Ne laser light, either directly or in a cascade-like effect dependent on increase in cell Ca2+, can cause cell stimulation.

Transforming growth factor-beta 1 and insulin-like growth factor-1 expression in ovarian endometriotic cysts: a preliminary study

Increased concentrations of TGF-beta 1 in endometriotic tissue are considered important in the pathophysiology of endometrial diseases since TGF-beta 1 may inhibit natural killer activity and induce angiogenesis and proliferation of endometrial stromal cells. In the present study we report on TGF-beta 1, IGF-1 and their receptor localization, as detected by Northern hybridization and immunohistochemistry, in ovarian endometriotic tissues removed during surgical procedures. We detected comparable expression of IGF-1 and IGF-1 receptor in the stromal and epithelial compartments, thus confirming disregulated expression of the IGF system in ovarian endometriosis. On the contrary, strongly increased TGF-beta 1 steady state level mRNA expression was detected in all endometriotic samples. In addition, we demonstrated weak TGF-beta 1 immunohistochemical expression in the epithelial lining and intense expression in the cellular stroma of ovarian endometriomas, thus suggesting that TGF-beta 1 could have an important role in the maintenance and propagation of the disease. On the basis of these preliminary results we can assume that TGF-beta 1, IGF-1 and their receptors may play an important role in the pathogenesis of endometriosis.

Regulation of mRNA and protein levels of beta1 integrin variants in human prostate carcinoma

Alterations of integrin expression levels in cancer cells correlate with changes in invasiveness, tumor progression, and metastatic potential. The beta1C integrin, an alternatively spliced form of the human beta1 integrin, has been shown to inhibit prostate cell proliferation. Furthermore, beta1C protein levels were found to be abundant in normal prostate glandular epithelium and down-regulated in prostatic adenocarcinoma. To gain further insights into the molecular mechanisms underlying abnormal cancer cell proliferation, we have studied beta1C and beta1 integrin expression at both mRNA and protein levels by Northern and immunoblotting analysis using freshly isolated neoplastic and normal human prostate tissue specimens. Steady-state mRNA levels were evaluated in 38 specimens: 33 prostatic adenocarcinomas exhibiting different Gleason's grade and five normal tissue specimens that did not show any histological manifestation of benign prostatic hypertrophy. Our results demonstrate that beta1C mRNA is expressed in normal prostate and is significantly down-regulated in neoplastic prostate specimens. In addition, using a probe that hybridizes with all beta1 variants, mRNA levels of beta1 are found reduced in neoplastic versus normal prostate tissues. We demonstrate that beta1C mRNA down-regulation does not correlate with either tumor grade or differentiation according to Gleason's grade and TNM system evaluation, and that beta1C mRNA levels are not affected by hormonal therapy. In parallel, beta1C protein levels were analyzed. As expected, beta1C is found to be expressed in normal prostate and dramatically reduced in neoplastic prostate tissues; in contrast, using an antibody to beta1 that recognizes all beta1 variants, the levels of beta1 are comparable in normal and neoplastic prostate, thus indicating a selective down-regulation of the beta1C protein in prostate carcinoma. These results demonstrate for the first time that beta1C and beta1 mRNA expression is down-regulated in prostate carcinoma, whereas only beta1C protein levels are reduced. Our data highlight a selective pressure to reduce the expression levels of beta1C, a very efficient inhibitor of cell proliferation, in prostate malignant transformation.

Transforming growth factor-beta1 in hemangioma of the ovary

Hemangioma of the ovary is extremely rare. We report the case of a 32-year-old woman who complained of pelvic pain due to a large right adnexal mass. On surgical exploration a 10 x 8 cm hemangioma of the ovary was resected. Expression of transforming growth factor-beta1 was studied, and the possible role of this molecule in the development of the tumor is discussed.

Insulin-like growth factor 1 expression in thyroid tumors

Insulin-like growth factor 1 (IGF-1) likely is involved in thyrocyte proliferation via autocrine mechanisms, but limited data are available on its in vivo expression in thyroid neoplasms. This prompted us to explore IGF-1 expression at the protein and mRNA levels and IGF-1 receptor (IGF-1rec) immunoreactivity in normal and neoplastic thyroids (50 adenomas and 53 carcinomas). We documented increased IGF-1 and IGF-1rec immunoreactivity in adenomas (31 of 50 and 40 of 50 cases, respectively) and carcinomas (38 of 53 and 42 of 53 cases) compared with normal thyroid, which only showed minimal immunoreactivity for the ligand and its receptor. A corresponding up-regulation of IGF-1 mRNA was documented in carcinomas, whereas adenomas exhibited down-regulated expression of IGF-1 mRNA. Immunoreactivity for IGF-1 and cognate receptor positively correlated with tumor diameter and wide intrathyroidal extension but not with patients' gender and age or with the stage of the tumors and the occurrence of lymph node metastases. These data emphasize a possible role of the IGF-1 system in thyroid tumorigenesis, as indicated by in vitro studies. In addition, the evaluation of IGF-1 and IGF-1rec immunoreactivity might have clinical implications, because it positively correlates with the aggressiveness of these tumors.

TGF-beta1 and IGF-1 expression are differently regulated by serum in metastatic and non-metastatic human breast cancer cells

Transforming growth factor-beta (TGF-beta) exerts an inhibitory effect on epithelial cell proliferation while insulin-like growth factor-1 (IGF-1) is a positive regulator of proliferation and together they may participate in driving neoplastic progression. The regulation of TGF-beta1 and IGF-1 gene expression was analyzed in an in vitro model of an estrogen receptor positive (ER+), non-metastatic (MCF-7) and an (ER-), metastatic (MDA-MB-435) breast cancer cell line, respectively. Our results indicate a loss of the regulation of TGF-beta1 and the gain of the expression and upregulation of IGF-1 pathways during malignant progression. These data demonstrate that two factors, convergent on cell growth, can have divergent roles in the regulation of the expression of TGF-beta1.

Insulin-like growth factor-I expression in normal and diseased endometrium

While the role of steroid hormones in the regulation of endometrial proliferation and differentiation is well established, the effects of growth factors and their receptors in normal and neoplastic endometrium remain a matter of debate. Previous studies have documented the positive effects of insulin-like growth factor-I (IGF-I) on epithelial cell proliferation and the active production of this growth factor in endometrial tissues. In view of decreased expression of transforming growth factor-beta1 (TGF-beta1), an antagonist of IGF-I, in endometrial carcinoma, we investigated the expression of IGF-I, at both the mRNA and protein levels, and the immunoreactivity for type I IGF-I receptor in 30 formalin-fixed, paraffin-embedded tissue samples of normal and neoplastic endometrium, in order to possibly clarify the role of IGF-I in endometrial proliferation and differentiation. Our results demonstrate a reduced expression of IGF-I mRNA in endometrial carcinomas compared with non-neoplastic tissues, despite equivalent immunohistochemical expression of IGF-I and IGF-I receptor. Our data suggest that IGF-I and its corresponding receptor may not be directly involved in endometrial cancer cell proliferation and differentiation in vivo, though other components of the IGF-I system (e.g., IGF binding proteins) may affect endometrial malignant transformation and tumor progression.

TGF-beta 1 and IGF-1 expression in atrophic post-menopausal endometrium

OBJECTIVES

Endometrial cells may synthetize cytokines and growth factors which may modulate some of the molecular mechanisms of endometrial proliferation and differentiation.

PATIENTS AND METHODS

We investigated the role of transforming growth factor beta-1 (TGF-beta 1), insulin-like growth factor-1 (IGF-1) and relative receptors in five tissue samples from atrophic post-menopausal endometria. The control group was represented by proliferative and secretory endometria from 10 healthy, normally-menstratued women. TGF-beta 1 and IGF-1 m-RNA expression was evaluated by Northern hybridization analysis, while TGF-beta 1 and IGF-1 receptors distribution was studied by immunohistochemistry.

RESULTS

In atrophic endometria Northern hybridization analysis showed a significant decrease of IGF-1 expression, and an increase of TGF-beta 1 expression compared to proliferative and secretory endometria. By immunohistochemistry it was demonstrated that TGF-beta 1 and IGF-1 receptors were both localized in cell cytoplasm, mainly in the stromal compartment.

CONCLUSIONS

The results of our study would suggest a possible role of IGF-1 and TGF-beta 1 in maintaining the quiescent differentiative state of atrophic post-menopausal endometrium. The persistence of IGF-1 and TGF-beta 1 receptors in epithelial compartment could play a key role in proliferative response of atrophic endometrium to exogenous hormone replacement therapy (HRT) or endogenous intervening high estrogens levels.

Insulin-like growth factor-1 and insulin-like growth factor receptor in thyroid tissues of patients with Graves' disease

Growth factors are frequently involved in the regulation of mitosis and differentiation of several cell types and insulin-like growth factor-1 (IGF-1) is actively involved in the thyroid stimulating hormone-mediated proliferation of thyrocytes. In view of the pivotal role of IGF-1 in thyrocyte proliferation and of the still unsettled role of this growth factor in the pathogenesis of hyperplastic thyroid lesions, we investigated the expression of IGF-1 and of its corresponding receptor, by means of immunohistochemistry, in the surgical specimens obtained from six patients with Graves' disease. Moreover, IGF-1 mRNA expression was analysed in one such case by means of Northern hybridisation. All samples showed consistent intracytoplasmic immunoreactivity for both IGF-1 and IGF-1 receptor; the vast majority of hyperplastic thyrocytes were strongly decorated by the two antibodies used in this study whereas stromal cells displayed IGF-1 immunoreactivity only. IGF-1 mRNA was markedly overexpressed in Graves' disease in comparison with normal thyroid tissues. The results of this study suggest that IGF-1 and IGF-1 receptor may be actively involved in the pathogenesis of Graves' disease; furthermore, IGF-1 and IGF-1 receptor apparently act by different mechanisms (paracrine vs. autocrine) as suggested by their differential expression in epithelial and stromal cells.

Polarized distribution of Na+/H+ exchanger isoforms in rabbit collecting duct cells

The present study describes two Na+/H+ exchanger (NHE) isoforms in an immortalized rabbit renal cortical collecting tubule cell line (RC.SV3). Na+/H+ exchange activity was assayed using fluorescence measurements of intracellular pH (pHi) in monolayers mounted in a cuvette containing two fluid compartments, making it possible to independently measure Na+/H+ exchange activity on either the apical or basolateral surface. RC.SV3 monolayers express Na+/H+ exchange activities in both the apical and basolateral membrane domains. The two exchangers have half-saturation constants (Km) for external sodium and sensitivities to dimethylamiloride, to HOE-694 and to cimetidine and clonidine consistant with the NHE-1 isoform on the basolateral cell surface and the NHE-2 isoform on the apical surface. Protein kinase A inhibition of basolateral exchanger activity was significantly higher than that of the apical exchanger. Protein kinase C significantly stimulated both exchangers equally. RT-PCR analysis found RNA for only NHE-1 and NHE-2, and immunofluorescence with an antibody against NHE-1 demonstrated a basolateral location for this isoform. The results suggest that RC.SV3 cells have two Na+/H+ exchange activities separated spatially to the two cellular membranes, with the NHE-1 and the NHE-2 isoforms located on the basolateral and the apical membranes, respectively.

Down-regulated expression of transforming growth factor beta 1 mRNA in endometrial carcinoma

Transforming growth factor beta1 (TGF-beta1) is a potent modulator of cell proliferation in vitro, and recent studies have demonstrated its overexpression in several different tumours; nevertheless, the molecular mechanisms of TGF-beta1 action on cell growth and differentiation have not been fully elucidated. To clarify the role of TGF-beta and its receptor in human endometrial proliferation and differentiation, TGF-beta1 expression at both the mRNA and protein levels has been evaluated by using Northern blotting and immunohistochemistry, in both normal (atrophic, proliferative and secretory) and neoplastic (adenocarcinoma) endometrial samples. This study demonstrates that TGF-beta1 mRNA expression is dramatically reduced in endometrial carcinomas with respect to non-neoplastic tissues, whereas the immunohistochemical expression of TGF-beta1 is enhanced in the epithelial component of endometrial carcinomas compared with non-neoplastic tissues. These data suggest that TGF-beta1 acts as a paracrine regulator of endometrial cell proliferation and that it may contribute to the carcinogenic mechanisms of endometrial carcinoma.

Increased expression of insulin-like growth factor 1 (IGF-1) in multinodular non toxic goiter

Thyroid cell growth and function both in vivo and in vitro, are mainly regulated by TSH. Recent studies have shown that growth factors including insulin-like growth factors (IGF-1) have an important role in the control of thyrocyte proliferation and differentiation. The aim of this study was to evaluate the expression of the IGF-1 gene by Northern analysis and the IGF-1 tissue protein by radioimmunoassay in multinodular euthyroid goiters. The study population consisted of 20 patients with multinodular goiter (14 females and 6 males) living in a non endemic geographic area. All patients were euthyroid at the time of surgery and submitted to total or subtotal thyroidectomy. Samples of normal thyroid tissue were obtained from three patients who were operated due to laryngeal carcinomas. The IGF-1 protein content was increased in non toxic multinodular goiter, 22 ng/g vs. 14 in controls (p<0.03), as was IGF-1 gene expression (p<0.05). The increase in the steady state mRNA content correlated with the increase in the protein content (r=0.665; p<0.005). These results suggest that IGF-1 may play a role in proliferation events involved in benign hyperplastic thyroid diseases.

Lack of correlation between mRNA expression and enzymatic activity of the aspartate aminotransferase isoenzymes in various tissues of the rat

Little is known about control of expression of basal levels of the aspartate aminotransferases which are ubiquitous 'house keeping' enzymes in vertebrates. We have measured both mRNA and activity levels for both isoenzymes in various rat tissues as a function of age. Patterns of mRNA expression for the two isoenzymes were similar in a particular tissue about differed widely between tissues. Surprisingly, there was no simple correlation between mRNA levels and specific activities of the enzyme products. We conclude that translation for mRNA for these two isoenzymes is subject to tissue-specific, and in some cases age-related, regulation.

Ttf1 gene-expression in human proliferating thyroid-diseases

TTF1 mRNA expression in the thyroid gland from 30 patients with thyroid proliferating diseases and 4 healthy donors used as normal controls was investigated using Northern blot analysis. Six patients affected by malignant thyroid carcinomas and six patients with adenoma were examined; moreover 18 patients with non malignant proliferating disease such as multinodular goiters were investigated. Determination of TTF1 mRNA revealed a significant decrease of the steady state mRNA levels in carcinomas and adenomas as compared to normal tissues. On the contrary, in patients affected by multinodular goiters variations were observed that seemed not to be directly associated with the pathological conditions.

Lactate dehydrogenase isoenzyme patterns in blood cells from histiocytosis X children

To find a clinical assay for histiocytosis X (HX) diagnosis, measurements were made of both activity and isoenzyme distribution of lactate dehydrogenase (LDH; EC 1.1.1.27) from the blood cells of 6 acute phase and 9 remission patients. A significant increase in the LDH activity measured in the monocytes and lymphocytes isolated from the blood of the acute phase patients was found. The increased activity was due to an enhancement of the normal pattern of LDH isoenzymes in these cells and not to a change in isoenzyme distribution. No increase was found in monocyte LDH isoenzymes from the patients in remission.

Helium-neon laser irradiation of rat liver mitochondria gives rise to a new subpopulation of mitochondria: isolation and first biochemical characterization

An experiment was performed to isolate the small atypical mitochondria produced during the irradiation of normal mitochondria with an He-Ne laser. Rat liver mitochondria were irradiated with a low-power continuous-wave He-Ne laser (energy dose, 5 J cm-2), followed by isolation using a sucrose gradient. In the irradiated sample, two bands were observed, one corresponding to normal mitochondria and the other to atypical mitochondria. Certain biochemical features of the mitochondria were investigated: mitochondrial enzyme activity and the presence of DNA and RNA were demonstrated. Hybridization experiments carried out with labelled mitochondrial probes, containing the genes for cytochrome oxidase subunit I and 12S rRNA, confirmed the mitochondrial nature of the isolated RNA.

Increase in RNA and protein synthesis by mitochondria irradiated with helium-neon laser

To gain further insight into the mechanism of cell photostimulation by laser light, both RNA and protein synthesis were measured in mitochondria irradiated with the low power continuous wave He-Ne laser (Energy dose: 5 Joules/cm2). Following mitochondrial irradiation, both the rate and amount of incorporation of alpha-[32P]UTP and L-[35S]methionine, used to monitor RNA and protein synthesis respectively, proved to increase. Electrophoretic analysis made of the synthesis products clearly shows that He-Ne laser irradiation stimulates the synthesis of all mitochondrial transcription and translation products.

The human alpha 1-antitrypsin gene is transcribed from two different promoters in macrophages and hepatocytes

In order to investigate the mechanism of expression of the human alpha 1-antitrypsin (alpha 1-AT) gene in macrophages, we have characterized the alpha 1-AT transcriptional units in these cells and discovered that there is a macrophage-specific promoter located approximately 2000 bp upstream of the hepatocyte-specific promoter. Transcription from the two alpha 1-AT promoters is mutually exclusive: the macrophage promoter is silent in hepatocytes and the hepatocyte promoter is silent in macrophages. In addition, in macrophages two distinct mRNAs are generated transcript by alternative splicing. These results suggest that alpha 1-AT gene transcription responds to two different cell-specific regulatory mechanisms.

Alu sequences transcription in X. laevis oocytes: nuclear-cytoplasmic partitioning and evidence for 3' end processing reactions

A large Alu-family cluster in the 5' flanking region of a human alpha 1-acid glycoprotein gene has been identified and sequenced. Individual members microinjected into X. laevis oocytes are transcribed only when canonical box A and B components of the split pol III promoter are present. Alu transcripts accumulate in the nucleus. An unusually short Alu transcript, able to assume a stable secondary structure, undergoes a 3' end processing reaction similar to the one required for tRNA 3' end maturation.

Kinetic studies of the uptake of aspartate aminotransferase and malate dehydrogenase into mitochondria in vitro

Kinetic measurements of the uptake of native mitochondrial aspartate aminotransferase and malate dehydrogenase into mitochondria in vitro were carried out. The uptake of both the enzymes is essentially complete in 1 min and shows saturation characteristics. The rate of uptake of aspartate aminotransferase into mitochondria is decreased by malate dehydrogenase, and vice versa. The inhibition is exerted by isoenzyme remaining outside the mitochondria rather than by isoenzyme that has been imported. The thiol compound beta-mercaptoethanol decreases the rate of uptake of the tested enzymes; inhibition is a result of interaction of beta-mercaptoethanol with the mitochondria and not with the enzymes themselves. The rate of uptake of aspartate aminotransferase is inhibited non-competitively by malate dehydrogenase, but competitively by beta-mercaptoethanol. The rate of uptake of malate dehydrogenase is inhibited non-competitively by aspartate aminotransferase and by beta-mercaptoethanol. beta-Mercaptoethanol prevents the inhibition of the rate of uptake of malate dehydrogenase by aspartate aminotransferase. These results are interpreted in terms of a model system in which the two isoenzymes have separate but interacting binding sites within a receptor in the mitochondrial membrane system.