Erratum to: Estrogen receptor beta binds Sp1 and recruits a corepressor complex to the estrogen receptor alpha gene promoter.

Erratum to: Breast Cancer Res Treat (2012), 134:569­581, DOI 10.1007/s10549-012-2090-9. Uunfortunately, authors could not find the original film from which the figure was drawn. Therefore, as suggested by the Editor, they have repeated the relative experiment, and ask to publish this new figure as a correction. The authors apologize for any inconvenience that it may cause.

Sperm metabolism in pigs: a role for peroxisome proliferator-activated receptor gamma (PPARγ).

Peroxisome proliferator-activated receptor gamma (PPARγ) is a nuclear hormone receptor expressed predominantly in adipose tissue, also implicated in energy homeostasis. In this study, we used western blotting and immunofluorescence techniques to demonstrate for the first time that pig spermatozoa express PPARγ. To investigate the functional role of PPARγ in pig sperm, we evaluated its action on different events that characterize the biology of sperm cells, i.e. motility, capacitation, viability and acrosome reaction, using the PPARγ-agonist 15-deoxy-12,14-prostaglandin J2 (PGJ2). In responses to PGJ2 treatment, motility, cholesterol efflux and tyrosine phosphorylation were increased, which broadens the role of PPARγ from that previously described in the literature, as it also acts to improve sperm functionality. To further our understanding of the significance of PPARγ in pig sperm, we focused its effects on lipid and glucose metabolism. Evaluation of triglyceride content and lipase, acyl-CoA dehydrogenase and G6PDH activities suggests that PPARγ induces energy expenditure in pig spermatozoa. These data represent a meaningful advance in the field of sperm energy metabolism. Taken together, our results demonstrate for the first time that PPARγ is expressed by pig sperm, thus improving its functionalities in terms of motility, capacitation, acrosome reaction, survival and metabolism.

Estrogen receptor beta binds Sp1 and recruits a corepressor complex to the estrogen receptor alpha gene promoter.

Human estrogen receptors alpha and beta are crucially involved in the regulation of mammary growth and development. Normal breast tissues display a relative higher expression of ER beta than ER alpha, which drastically changes during breast tumorogenesis. Thus, it is reasonable to suggest that a dysregulation of the two estrogen receptor subtypes may induce breast cancer development. However, the molecular mechanisms underlying the potential opposing roles played by the two estrogen receptors on tumor cell growth remain to be elucidated. In the present study, we have demonstrated that ER beta overexpression in breast cancer cells decreases cell proliferation and down-regulates ER alpha mRNA and protein content, along with a concomitant repression of estrogen-regulated genes. Transient transfection experiments, using a vector containing the human ER alpha promoter region, showed that elevated levels of ER beta down-regulated basal ER alpha promoter activity. Furthermore, site-directed mutagenesis and deletion analysis revealed that the proximal GC-rich motifs at -223 and -214 are critical for the ER beta-induced ER alpha down-regulation in breast cancer cells. This occurred through ER beta-Sp1 protein-protein interactions within the ER alpha promoter region and the recruitment of a corepressor complex containing the nuclear receptor corepressor NCoR, accompanied by hypoacetylation of histone H4 and displacement of RNA-polymerase II. Silencing of NCoR gene expression by RNA interference reversed the down-regulatory effects of ER beta on ER alpha gene expression and cell proliferation. Our results provide evidence for a novel mechanism by which overexpression of ER beta through NCoR is able to down regulate ER alpha gene expression, thus blocking ER alpha's driving role on breast cancer cell growth.

Bergapten induces ER depletion in breast cancer cells through SMAD4-mediated ubiquitination.

ERα function is crucial for the development of normal mammary gland as well as in the process of progression of breast cancer cells. Signals that target receptor levels contribute to regulate estrogens effects in the cells. An intricate cross-regulation has been documented between ERα and TGF-ß down-stream molecules: SMAD2, SMAD3, and SMAD4, that can bind ERα and regulate their signaling. Thus, identification of natural anticancer drugs able to influence the latter molecule might provide alternative choices for breast cancer treatment. Taking into account our previous published data we wanted to study the effect of 5-Methoxypsoralen (bergapten) on ERα and on TGF-ß pathway. We reported that bergapten, a coumarin containing compound, effectively depletes ERα in MCF-7 breast cancer sensitive cells and in tamoxifen-resistant clone. The decrease of ERα protein after bergapten treatment results from the ubiquitine-proteasome pathway as demonstrated by the use of MG-132. IP experiments with ER antibody, demonstrated that the protein has physical interaction with SMAD4 and poly-ubiquitine and the amount of ubiquitinated receptor, linked to SMAD4, is greater under bergapten. The crucial role played by SMAD4, in this process, emerges from the observation that in breast cancer cells, silencing of SMAD4, resulted in increased expression of endogenous ERα in both control and bergapten-treated cells, compared to wild- type cells. The same results were confirmed in siRNA TGF-ß RII cells. The results suggest a novel negative regulation of ERα by TGF-ß/SMAD4 in breast cancer cells and indicate that the SMAD4 protein is involved in the degradation of ERα induced by bergapten. We propose that bergapten may efficiently act as a natural antitumoral agent, able to deplete ERα from breast cancer tamoxifen-sensitive and resistant cells, thereby retraining the effect of membrane signals targeting ERα and in such way its mitogenic potentiality.

Thyroid hormone modulates androgen and oestrogen receptor content in the Sertoli cells of peripubertal rats.

A possible role of tri-iodothyronine (T3) on the interplay between testicular steroids and Sertoli cells has been investigated on the basis of previous findings demonstrating a direct inhibitory influence of T3 on aromatase activity and oestradiol production in peripuberal Sertoli cells. In this context, the present study was focused on the effects of T3 on oestrogen receptor (ER) and androgen receptor (AR) contents in the cytosol and nucleus of Sertoli cells isolated from 2-, 3- and 4-week-old euthyroid, hypothyroid and hypothyroid treated rats. Hypothyroidism was induced by the oral administration of 0.025% methimazole (MMI) from birth until the rats were killed at 2, 3 and 4 weeks of age. Half of the MMI-treated animals were injected i.p. with L-tri-iodothyronine (T3; 3 micrograms/100 g body weight) during the last week before death. Sertoli cells from all groups were initially cultured under basal conditions for the first 24 h and subsequently in the presence of testosterone with or without T3 for an additional 24 h. Hypothyroidism was associated with severe impairment of body as well as testicular growth. Euthyroid ERs showed an elevated Kd (0.76 nM) which was similar in the different age groups investigated. The in vitro addition of T3 or testosterone induced a decrease in ER content and this decrease was greater after exposure to both hormones. In 2- and 3-week-old hypothyroid rats, ER content was markedly increased and was reversed in euthyroid rats when T3 was given in vivo. When ERs were assayed in the Sertoli cell nucleus and cytoplasm of 2- and 3-week-old animals, a strong relationship in ER content in the two cellular compartments was observed. Neither of the hormones tested seemed to affect the AR content in the nucleus significantly, while the in vitro addition of testosterone or T3 or both hormones together augmented the ARs in the cytosol to a greater extent, resulting in an increase in their total (cytosolic and nuclear) content in the cells. The present data suggest that T3 down-regulates ERs and up-regulates ARs in peripuberal Sertoli cells. The additive effect of testosterone and T3 in up-regulating ARs could possibly involve a role for T3 in influencing the androgen responsiveness of the Sertoli cells during spermatogenesis.

Influence of thyroid hormone on androgen metabolism in peripuberal rat Sertoli cells.

The aim of the present study was to investigate the influence of thyroid hormones on androgen metabolism in Sertoli cells isolated from 3- and 4- week-old rats. Hypothyroidism was induced by the oral administration of 0.025% methimazole (MMI) from birth until the rats were killed at 3 and 4 weeks of age. Half of the MMI-treated animals were injected i.p. with L-triiodothyronine (T3 3 micrograms/100 g body weight) during the last week before death. Sertoli cells from all groups were initially cultured under basal conditions for the first 24 h and subsequently in the presence of testosterone with or without T3 for an additional 24 h. Hypothyroidism was associated with severe impairment of body as well as testicular growth. Indeed, body and testicular weights were similar in 4-week-old hypothyroid animals to those in 3-week-old control rats. Testosterone metabolism in Sertoli cells isolated from 3- and 4-week-old hypothyroid rats was mainly expressed by the lowering of 5 alpha-dihydrotestosterone + androstane 3 alpha, 17 beta-diol and an enhanced formation of 5 alpha-reduced steroids with poor androgenic properties (e.g. 5 alpha-androstane, 3, 17 alpha-dione (androstanedione), 5 alpha-androstane, 3-ol-17-one (androsterone)). Treatment of the same group of animals with T3 in vivo and in vitro did not influence the pattern of 5 alpha-reductase steroids substantially. The most striking finding in the Sertoli cells of 3-week-old hypothyroid rats was the dramatic enhancement of oestradiol formation which persisted to a lesser extent 1 week later.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of triiodothyronine administration on estrogen receptor contents in peripuberal Sertoli cells.

The effects of thyroid hormone on androgen metabolism in peripuberal Sertoli cells through the inhibition of estradiol production have been reported previously. It was our intention to investigate further the possible role of thyroid hormone on the interaction between testicular steroids and Sertoli cells by analyzing the effects of triiodothyronine (T3) on estrogen receptor content in 2-, 3- and 4- week-old euthyroid rats. Triiodothyronine treatment (3 micrograms/100 body wt per day) given during the last week prior to sacrifice resulted in reduced testicular growth in 2-week-old animals. Sertoli cells from all groups were cultured initially under basal conditions for the first 24 h and subsequently in the presence of testosterone and/or T3 for the additional 24 h. The in vitro addition of T3 induced a decrease of estrogen receptors (ERs) in 2- and 3-week-old animals that appeared more pronounced especially in the presence of T3 and testosterone. When T3 was tested in vivo we noticed that the decrease of ER content was even greater in all three groups under the in vitro influence of both T3 and testosterone. In 3-week-old animals a simultaneous assay of ERs in both nuclear and cytoplasmic compartments was performed. The ER concentrations in the nucleus were closely related to those of the cytoplasm. The in vivo administration of T3 was responsible for a greater decrease of ERs in the nucleus than in the cytosol. On the basis of these results, and in agreement with our previous data, we speculate that the effect of T3 in the maturational events of Sertoli cells could involve both estradiol production and ER content.

Effect of oestradiol and insulin on the proliferative pattern and on oestrogen and progesterone receptor contents in MCF-7 cells.

In a long-term experiment MCF-7 cells showed an exponential proliferation rate in fetal calf serum while they become quiescent in growth-factor- and steroid-free serum. The mitogenic activity of this cell line was increased by oestradiol and insulin, exposure to both hormones showing a synergic effect. These mitogen-mediated effects are inhibited by genistein a phytoestrogen which, by itself at the doses used, did not affect either the basal proliferation rate or the total protein content. Immunoblotting and Scatchard analysis reveal respectively that insulin increases the oestrogen receptor (ER) content and its binding capacity. The presence of genistein decreases the ER content and completely abolishes the binding capacity of this protein. Insulin is able to increase progesterone receptor (PR) levels while, in the presence of genistein, the above-reported effect was completely abolished. On the basis of the latter data the authors suggest that insulin is able to affect the phosphorylation status of ER and PR, inducing functional changes in both proteins, although this was in the absence of their natural ligands. Indeed, the presence in the medium of a tyrosine kinase inhibitor such as genistein could substantially decrease both ER and PR levels in these cells.

Epididymal and sex accessory gland secretions in transfusion-dependent beta-thalassemic patients: evidence of an impaired prostatic function.

Neutral alpha-glucosidase levels as epididymal marker, fructose levels as vesicular marker, zinc, citric acid and prostate specific antigen levels as prostatic markers were measured in the seminal plasma of eight transfusion-dependent beta-thalassemic patients in order to study epididymal and sex accessory gland secretions (eighteen subjects served as controls). FSH and LH as well as total and free testosterone were detected displaying unaltered serum values. Ejaculate of patients showed normal sperm count and low sperm motility, in the meantime seminal plasma exhibited unaltered both neutral alpha-glucosidase and fructose values but low levels of zinc, citric acid and prostate specific antigen were noticed as well. These data suggest an impaired prostatic secretion in the thalassemic patients studied. A local iron toxicity on the prostatic tissue could be supported by the decrease of its specific markers observed only in the subgroup of patients with high ferritin serum levels.

A time course study on the "in vitro" effects of T3 and testosterone on androgen and estrogen receptors in peripuberal primary rat Sertoli cells.

The effect of Tri-iodothyronine (T3) administration leading to the precocius differentiation of Sertoli cell in prepuberal rats has been previously shown. The functional maturation of Sertoli cells is associated with changes in androgen metabolism. We have recently demonstrated that T3 influences androgen metabolism in Sertoli cells by inhibiting aromatase activity and reduces drastically the ER contents in peripubertal hypothyroid rats. To better understand the role of T3 in modulating steroid action on Sertoli cells, we performed a time course study evaluating the in vitro effects of T3 and testosterone (T) on androgen (ARs) and estrogen (ERs) receptor content in Sertoli cells isolated from two weeks old Wistar rats. ARs and ERs basal levels did not change during the time course study indicating that the exposure to culture medium per se did not affect either receptor type. After 24 hrs of incubation with either T3 or T, a decrease of ERs in both nucleus and cytosol was observed. Such a decrease was augmented by the simultaneous administration of both hormones. ARs displayed a different temporal pattern in the two cellular compartments and exhibited an earlier rise in the cytosol induced by either T3 or T. At 36 hrs, ARs were significantly enhanced in both compartments in response to either T or T3 exposure while combined hormonal treatment caused an additive increase compared with the single treatment group. As a consequence of the opposite behaviour pattern displayed by ARs and ERs, the ratio between total ARs and ERs contents was increased after 24 hrs of exposure to hormonal treatment. To evaluate if treatments performed induced a functional maturation of Sertoli cells, transferrin levels in culture medium were measured. The increase of this protein paralleled that of ARs content as well as that of ARs/ERs ratio. This study demonstrates that thyroid hormone induces a progressive increase of (AR)/(ER) ratio in the differentiating Sertoli cells bringing them to a prevalent androgen dependency along their functional maturation.

DAX-1, as an androgen-target gene, inhibits aromatase expression: a novel mechanism blocking estrogen-dependent breast cancer cell proliferation.

Sexual hormones, estrogens and androgens, determine biological response in a tissue- and gender-specific manner and have a pivotal role in endocrine-mediated tumorigenesis. In situ estrogen production by aromatase is a critical determinant for breast cancer growth and progression. On the contrary, clinical and in vitro studies indicate that androgens have a protective role in mammary carcinogenesis. Here, we demonstrated, in hormone-dependent breast cancer cells, the existence of a functional interplay between the androgen receptor (AR), the orphan nuclear receptor DAX-1 and the aromatase enzyme involved in the inhibition of the estrogen-dependent breast cancer cell proliferation exerted by androgen signaling. Indeed, our results revealed, in MCF-7 cells, that ligand-activated AR induces the expression of the orphan nuclear receptor DAX-1 by direct binding to a newly identified androgen-response-element within the DAX-1 proximal promoter. In turn, androgen-induced DAX-1 is recruited, in association with the corepressor N-CoR, within the SF-1/LRH-1 containing region of the aromatase promoter, thereby repressing aromatase expression and activity. In elucidating a novel mechanism by which androgens, through DAX-1, inhibit aromatase expression in breast cancer cell lines, these findings reinforce the theory of androgen- opposing estrogen-action, opening new avenues for therapeutic intervention in estrogen-dependent breast tumors.

Progesterone through progesterone receptors affects survival and metabolism of pig sperm.

Progesterone receptors (PR) through interaction with the specific ligand progesterone (PRG), play a central coordinate role in different reproductive events. In this study conventional PR were identified in boar spermatozoa by Western blotting. Immunofluorescence techniques indicate that PR are located at sperm acrosomal region, suggesting a possible role in the oocyte fertilization events. Treatment with 17-hydroxyprogesterone (17-OHP) enhanced viability and induced cholesterol efflux, serine and tyrosine phosphorylation, p-Bcl2, p-Akt that are known hallmarks of capacitation in sperm. The analysis of the triglyceride contents, lipase and acyl-CoA dehydrogenase activities, as well as the G6PDH activity, was conducted so as to address whether there was an increase in energy expenditure via 17-OHP through the PR. Taken together these results, particularly the 17-OHP action on boar sperm lipid and glucose metabolism, give emphasis to the role of PR in sperm physiology within the oviductal environment. Moreover the present study highlights, the effect of PRG via PR on boar sperm survival, renewing the role of this hormone in male reproduction as candidate for boar fertility. Thus the present research contributes to further elucidating the role of progesterone on the physiological regulation of the most relevant spermatozoa functions for a successful fertilization.

Evidence that bergapten, independently of its photoactivation, enhances p53 gene expression and induces apoptosis in human breast cancer cells.

Psoralens (5-MOP and 8-MOP), a class of naturally occurring compounds, in combination with ultraviolect light are potent modulators of epidermal cell growth and differentiation. For a long time, photo-chemotherapy has been used in the treatment of psoriasis where it can reduce the number of cycling keratinocytes and decrease the IGF-1 receptors. However, the molecular mechanism of PUVA therapy remains unclear. In this study, we have evaluated, for the first time, in MCF-7 and SKBR-3 breast cancer cells the effects of 5-MOP (Bergapten), independently of its photoactivation, on the signalling pathways involved in cell cycle arrest and in apoptosis. Drug treatment induced a block in the G0/G1 phase and increased mRNA and protein levels of p53 and p21waf. These data correlate with a functional activation of caspase 8/caspase 9 together with DAPI staining and DNA ladder. Bergapten can transactivate p53 gene promoter in these cells and site-direct mutagenesis studies showed that the binding sequence of the nuclear factor NF-Y on p53 promoter is required for 5-MOP responsiveness. Besides, Bergapten increases NF-Y nuclear translocation through p38 MAPK activation. The same treatment impairs the PI3Kinase/AKT survival signal, in hormone-dependent MCF-7 cells even in the presence of IGF-I/E2 mitogenic factors. Here, we demonstrated that Bergapten, independently on the exposure to UV, generates membrane signalling pathways able to address apoptotic responses in breast cancer cells and to counteract the stimulatory effect of IGF-I/E2 on estrogen-receptor positive MCF-7 cell growth and progression.

The estrogen receptor alpha:insulin receptor substrate 1 complex in breast cancer: structure-function relationships.

BACKGROUND: Insulin receptor substrate 1 (IRS-1) is a signaling molecule that exerts a key role in mediating cross talk between estrogen receptor alpha (ERalpha) and insulin-like growth factor 1 (IGF-1) in breast cancer cells. Previously, we demonstrated that a fraction of IRS-1 binds ERalpha, translocates to the nucleus, and modulates ERalpha-dependent transcription at estrogen response elements (ERE). Here, we studied structure-function relationships of the ERalpha:IRS-1 complex under IGF-1 and/or estradiol (E2) stimulation. MATERIALS AND METHODS: ERalpha and IRS-1 deletion mutants were used to analyze structural and functional ERalpha/IRS-1 interactions. IRS-1 binding to ERE and IRS-1 role in ERalpha-dependent ERE transcription was examined by chromatin immunoprecipitation and gene reporter analysis, respectively. The requirement for IRS-1 in ERalpha function was tested with RNAi technology. RESULTS: Nuclear translocation of IRS-1 was induced by E2, IGF-1, and a combination of both stimuli. ERalpha/IRS-1 binding was direct and involved the activation function-1 (AF-1)/DNA binding domain (DBD) region of ERalpha and two discrete regions of IRS-1 (the N-terminal pleckstrin homology domain and a region within the C-terminus). IRS-1 knock down abrogated IGF-1-dependent transcriptional activity of unliganded ERalpha, but induced the activity of liganded ERalpha. CONCLUSIONS: ERalpha/IRS-1 interactions are direct and involve the ERalpha AF-1/DBD domain and IRS-1 domains mapping within N- and C-terminus. IRS-1 may act as a repressor of liganded ERalpha and coactivator of unliganded ERalpha.

Insulin receptor substrate 1 is a target for the pure antiestrogen ICI 182,780 in breast cancer cells.

The pure antiestrogen ICI 182,780 inhibits insulin-like growth factor (IGF)-dependent proliferation in hormone-responsive breast cancer cells. However, the interactions of ICI 182,780 with IGF-I receptor (IGF-IR) intracellular signaling have not been characterized. Here, we studied the effects of ICI 182,780 on IGF-IR signal transduction in MCF-7 breast cancer cells and in MCF-7-derived clones overexpressing either the IGF-IR or its 2 major substrates, insulin receptor substrate 1 (IRS-1) or src/collagen homology proteins (SHC). ICI 182,780 blocked the basal and IGF-I-induced growth in all studied cells in a dose-dependent manner; however, the clones with the greatest IRS-1 overexpression were clearly least sensitive to the drug. Pursuing ICI 182,780 interaction with IRS-1, we found that the antiestrogen reduced IRS-1 expression and tyrosine phosphorylation in several cell lines in the presence or absence of IGF-I. Moreover, in IRS-1-overexpressing cells, ICI 182,780 decreased IRS-1/p85 and IRS-1/GRB2 binding. The effects of ICI 182,780 on IGF-IR protein expression were not significant; however, the drug suppressed IGF-I-induced (but not basal) IGF-IR tyrosine phosphorylation. The expression and tyrosine phosphorylation of SHC as well as SHC/GRB binding were not influenced by ICI 182,780. In summary, downregulation of IRS-1 may represent one of the mechanisms by which ICI 182,780 inhibits the growth of breast cancer cells. Thus, overexpression of IRS-1 in breast tumors could contribute to the development of antiestrogen resistance.

Adnexal gland secretion markers in unexplained asthenozoospermia.

Prostatic acid phosphatase, prostate-specific antigen, and zinc as markers of prostate, and fructose as marker of seminal vesicles were investigated in the seminal plasma of 35 idiopathic asthenozoospermic and 20 normal subjects to evaluate their relationship with sperm motility. Total seminal plasma levels of the three prostatic markers and, to a lesser extent, total fructose levels were lower in asthenozoospermic patients, and in all the pooled subjects, the same levels were directly correlated with the motility of ejaculated spermatozoa. When the levels of the biochemical markers were expressed as concentrations in seminal plasma, only prostatic acid phosphatase levels remained lower in asthenozoospermic patients and they maintained a direct correlation with sperm motility in all the pooled subjects. The PAP/Zn/Fr (representing the ratio between PAP concentration and free Zn available for spermatozoan uptake) was lower in asthenozoospermic patients and it was also directly related to sperm motility in all the pooled subjects. These data suggest that altered sperm motility is associated with a probable impairment of sex accessory gland function in subjects with idiopathic asthenozoospermia, while prostatic acid phosphatase seems mainly related to sperm motility.

The evaluation of free-L-carnitine, zinc and fructose in the seminal plasma of patients with varicocele and normozoospermia.

The function of the epididymis and of the sex accessory glands have been investigated in a selected group of varicocele patients with normal sperm count. In the seminal plasma of these patients free-L-carnitine, fructose and zinc levels were determined as functional markers respectively of epididymis, seminal vesicles and prostate. Despite the unvaried free-L-carnitine and fructose levels, zinc levels were significantly lower (p less than 0.001) than in the control group. The Zn/F ratio, an index of the ratio between the prostatic and vesicular secretions, resulted also lower (p less than 0.01) with respect to the controls. The authors suggest that the impaired prostatic function could arise from the decreased venous drainage in the vesico-prostatic plexus. In the same patients sperm motility resulted significantly lower than in the controls, and was positively related to zinc levels (r = 0.44, p less than 0.01) and, to a higher degree, to the Zn/F ratio (r = 0.62, p less than 0.001). Our data show that in this selected group of varicocele patients with a not yet altered tubular epididymal unit, sex accessory gland secretions can influence, per se, the motility of the ejaculated spermatozoa.

Role of IRS-1 signaling in insulin-induced modulation of estrogen receptors in breast cancer cells.

Cross-talk between steroid hormones and polypeptide growth factors regulates the growth of hormone-responsive breast cancer cells. For example, in the MCF-7 human breast cancer cell line, insulin up-regulates estrogen receptor (ER) content and binding capacity. Since the insulin receptor (IR) substrate 1 (IRS-1) is one of the core signaling elements transmitting mitogenic and metabolic effects of insulin, we investigated whether IRS-1 is also required for the insulin-induced function of the ER. The effects of insulin on the ER were compared in MCF-7 cells and MCF-7-derived cell lines with decreased levels (by approximately 80%) of IRS-1 due to the expression of IRS-1 antisense RNA. The severe IRS-1 deficiency in MCF-7 cells was associated with (1) reduced mitogenic response to 20 ng/ml insulin and 10% calf serum (CS), but not to 1 nM estradiol (E2); (2) loss of insulin-E2 synergism; (3) up-regulation of ER protein expression and binding capacity; and (4) loss of insulin-induced regulation of ER tyrosine phosphorylation. In conclusion, the data confirm the existence of the IR-ER cross-talk and suggest that IRS-1-dependent signaling may contribute to the negative regulation of the ER expression and function in MCF-7 cells.

Effects of short-term high-dose testosterone propionate administration on medium molecular-weight proteins of human seminal plasma.

Effects of short-term high-dose testosterone propionate treatment on medium molecular-weight proteins (lactoferrin, albumin, prostatic acid phosphatase, prostate specific antigen) and on zinc and fructose levels were investigated in the seminal plasma of seven normal volunteers. A significant reduction in levels of prostatic-acid phosphatase, zinc and, to a lesser degree, prostate-specific antigen, lactoferrin and fructose was observed on the 14th day of androgen treatment, concomitantly with the maximal increase in free androgen-circulating levels. The data obtained suggest that testosterone administration may induce a reduction in the sex accessory-gland secretion. Indeed, this effect tends to disappear with withdrawal of hormone treatment. Therefore, the authors suggest a close follow-up of prostatic and vesicular function during the long-term high-dose testosterone intake, used frequently as anabolic treatment by athletes and body builders.