Expression of activin/inhibin receptor and binding protein genes and regulation of activin/inhibin peptide secretion in human adrenocortical cells

Differential expression of activin βA and βB genes in female allotriploid and diploid red crucian carp Carassius auratus red var

activin β_A and β_B from diploid and allotriploid crucian carp were cloned.The differential expression of activin β_A and β_B genes in female allotriploid and diploid red crucian carp Carassius auratus red var. were studied and found to be expressed in all the tested tissues; particularly, the expression of activin β_A and β_B was elevated in the ovaries of allotriploids and differential expression in pituitaries during the non-breeding season and the breeding season period. The immunohistochemistry indicated that the abnormal triploid ovaries were dominated by small oogonium-like cells with dense signals and that the elevated expression of activin β_A and β_B in the ovaries of allotriploids may be related to allotriploid sterility.

ACTH-induced stress in weaned sows impairs LH receptor expression and steroidogenesis capacity in the ovary

BACKGROUND

Stress has been proved to impair the porcine reproduction soundly. Endocrine disruption, which is closely related to the persistent follicles, is possibly one of the results of stress, although the mechanism is unclear. Since the expression of luteinizing hormone receptor (LHR) in ovarian follicular wall and concentrations of steroid hormone in follicular fluid are related to the development of persistent follicles, this study is designed to evaluate the effect of administered adrenocorticotrophic hormone (ACTH) to weaned pigs on their ovarian steroidogenesis capacity and LHR expression.

METHODS

Ten multiparous sows were weaned and randomly divided into two groups (n = 5 each). Sows received 1 IU/kg ACTH (ACTH group) or saline (control group) every 8 h from days 3-9 after jugular vein intubation. Blood samples were collected throughout the experiment, and ovaries were collected after slaughter on day 10. Follicular fluid (FF) was used to determine the steroid hormone concentrations. The ovarian follicle wall was obtained and stored in liquid nitrogen to detect mRNA levels.

RESULTS

The plasma cortisol concentration was significantly (P < 0.01) elevated after ACTH injection. The estradiol (E₂) and androstenedione (ASD) concentrations in FF were significantly lower (P < 0.05) in the ACTH group than in the control group. The LHR, 3β-hydroxysteroid dehydrogenase (3β-HSD), cytochrome P450 aromatase (P450arom), and cytochrome P450 17a-hydroxylase (P450c17) mRNA levels were significantly (P < 0.05) reduced in the ACTH group. The steroidogenic acute regulatory protein (StAR) level and cytochrome P450 side-chain cleavage (P450scc) was lower in the ACTH group than in the control group, but the difference was not statistically significant (P > 0.05). Immunostaining results revealed 3β-HSD,P450c17, and LHR expression in theca cells, and P450arom expression in granulosa cells. Immunohistochemical staining showed significant differences in the distribution of 3β-HSD, P450c17, LHR, and P450arom between the two groups.

CONCLUSIONS

These findings indicated that ACTH significantly diminished the LHR expression and steroidogenesis capacity of the ovaries of weaned sows.

Role of ACTH in the Interactive/Paracrine Regulation of Adrenal Steroid Secretion in Physiological and Pathophysiological Conditions

In the normal human adrenal gland, steroid secretion is regulated by a complex network of autocrine/paracrine interactions involving bioactive signals released by endothelial cells, nerve terminals, chromaffin cells, immunocompetent cells, and adrenocortical cells themselves. ACTH can be locally produced by medullary chromaffin cells and is, therefore, a major mediator of the corticomedullary functional interplay. Plasma ACTH also triggers the release of angiogenic and vasoactive agents from adrenocortical cells and adrenal mast cells and, thus, indirectly regulates steroid production through modulation of the adrenal blood flow. Adrenocortical neoplasms associated with steroid hypersecretion exhibit molecular and cellular defects that tend to reinforce the influence of paracrine regulatory loops on corticosteroidogenesis. Especially, ACTH has been found to be abnormally synthesized in bilateral macronodular adrenal hyperplasia responsible for hypercortisolism. In these tissues, ACTH is detected in a subpopulation of adrenocortical cells that express gonadal markers. This observation suggests that ectopic production of ACTH may result from impaired embryogenesis leading to abnormal maturation of the adrenogonadal primordium. Globally, the current literature indicates that ACTH is a major player in the autocrine/paracrine processes occurring in the adrenal gland in both physiological and pathological conditions.

Mutual effects of melatonin and activin on induction of aldosterone production by human adrenocortical cells

Melatonin has been reported to suppress adrenocorticotropin (ACTH) secretion in the anterior pituitary and cortisol production in the adrenal by different mechanisms. However, the effect of melatonin on aldosterone production has remained unknown. In this study, we investigated the role of melatonin in the regulation of aldosterone production using human adrenocortical H295R cells by focusing on the activin system expressed in the adrenal. Melatonin receptor MT1 mRNA and protein were expressed in H295R cells and the expression levels of MT1 were increased by activin treatment. Activin increased ACTH-induced, but not angiotensin II (Ang II)-induced, aldosterone production. Melatonin alone did not affect basal synthesis of either aldosterone or cortisol. However, melatonin effectively enhanced aldosterone production induced by co-treatment with ACTH and activin, although melatonin had no effect on aldosterone production induced by Ang II in combination with activin. These changes in steroidogenesis became apparent when the steroid production was evaluated by the ratio of aldosterone/cortisol. Melatonin also enhanced dibutyryl-AMP-induced aldosterone/cortisol levels in the presence of activin, suggesting a functional link to the cAMP-PKA pathway for induction of aldosterone production by melatonin and activin. In accordance with the data for steroids, ACTH-induced, but not Ang II-induced, cAMP synthesis was also amplified by co-treatment with melatonin and activin. Furthermore, the ratio of ACTH-induced mRNA level of CYP11B2 compared with that of CYP17 was amplified in the condition of treatment with both melatonin and activin. In addition, melatonin increased expression of the activin type-I receptor ALK-4 but suppressed expression of inhibitory Smads6/7, leading to the enhancement of Smad2 phosphorylation. Collectively, the results showed that melatonin facilitated aldosterone production induced by ACTH and activin via the cAMP-PKA pathway. The results also suggested that mutual enhancement of melatonin and activin receptor signaling is involved in the induction of aldosterone output by adrenocortical cells.

Maternal Anxiety and the Second-Trimester Prenatal Screening: A Prospective Cohort Study

OBJECTIVE

Assessing the effects of maternal anxiety on the markers and results of quadruple screening and on maternal anxiety after receiving positive results.

METHODS

This prospective cohort study evaluated 1,595 pregnant women referred for prenatal visits. Maternal state/trait anxiety levels were measured, then quadruple screening was performed by measuring serum α-fetoprotein (AFP), β-human chorionic gonadotropin, inhibin A, and unconjugated estriol (UE3). After receiving the results, the state/trait anxiety was remeasured. Amniocentesis was performed for screening-positive mothers.

RESULTS

High prescreening maternal anxiety was associated with lower rates of elevated AFP (OR, 0.27; 95% CI, 0.1-0.74) and elevated inhibin A (OR, 0.38; 95% CI, 0.15-0.98). High maternal anxiety was associated with higher rates of decreased UE3 (OR, 1.8; 95% CI, 1.06-3.08). There were no significant associations between prescreening maternal anxiety and the final screening or amniocentesis results. Among the screening-positive mothers, those who had high state/trait anxiety before screening had higher anxiety scores after receiving positive results compared to those with low prescreening anxiety levels (52.9 ± 10.8 vs. 43.7 ± 10.3).

CONCLUSION

High prescreening maternal anxiety is associated with lower rates of elevated AFP and inhibin A and higher rates of decreased UE3. However, maternal anxiety does not affect the final screening or amniocentesis result. High maternal state/trait anxiety before screening is associated with significantly higher maternal anxiety after the receipt of positive results.

Reprint of: Betaglycan: a multifunctional accessory

Betaglycan is a co-receptor for the TGFβ superfamily, particularly important in establishing the potency of its ligands on their target cells. In recent years, new insights have been gained into the structure and function of betaglycan, expanding its role from that of a simple co-receptor to include additional ligand-dependent and ligand-independent roles. This review focuses on recent advances in the betaglycan field, with a particular emphasis on its newly discovered actions in mediating the trafficking of TGFβ superfamily receptors and as a determinant of the functional output of TGFβ superfamily signalling. In addition, this review encompasses a discussion of the emerging roles of the betaglycan/inhibin pathway in reproductive cancers and disease.

Inhibins and activins: their roles in the adrenal gland and the development of adrenocortical tumors

The adrenal gland is composed of two separate endocrine tissues that control a multitude of bodily functions in their adaptation to external and internal stressors through hormone secretion. The functions of the adrenal gland are regulated by circulating, neural and local factors that ensure proper cell growth and hormone production. Activins and inhibins are among the locally expressed growth factors affecting adrenal cell function. They have been found to influence several aspects of adrenal cell development, adrenocortical steroidogenesis, adrenocortical tumor formation and adrenomedullary cell differentiation. Especially the finding that inhibin α-subunit knockout mice develop adrenocortical carcinomas after gonadectomy has prompted research on the physiological and pathophysiological roles of activin and inhibin in the adrenal cortex. It is now clear that both peptides control adrenocortical physiology and are involved in adrenocortical tumorigenesis at multiple levels, both in murine models as well as in human patients.

Betaglycan: a multifunctional accessory

Betaglycan is a co-receptor for the TGFβ superfamily, particularly important in establishing the potency of its ligands on their target cells. In recent years, new insights have been gained into the structure and function of betaglycan, expanding its role from that of a simple co-receptor to include additional ligand-dependent and ligand-independent roles. This review focuses on recent advances in the betaglycan field, with a particular emphasis on its newly discovered actions in mediating the trafficking of TGFβ superfamily receptors and as a determinant of the functional output of TGFβ superfamily signalling. In addition, this review encompasses a discussion of the emerging roles of the betaglycan/inhibin pathway in reproductive cancers and disease.

Development and function of the human fetal adrenal cortex: a key component in the feto-placental unit

Continuous efforts have been devoted to unraveling the biophysiology and development of the human fetal adrenal cortex, which is structurally and functionally unique from other species. It plays a pivotal role, mainly through steroidogenesis, in the regulation of intrauterine homeostasis and in fetal development and maturation. The steroidogenic activity is characterized by early transient cortisol biosynthesis, followed by its suppressed synthesis until late gestation, and extensive production of dehydroepiandrosterone and its sulfate, precursors of placental estrogen, during most of gestation. The gland rapidly grows through processes including cell proliferation and angiogenesis at the gland periphery, cellular migration, hypertrophy, and apoptosis. Recent studies employing modern technologies such as gene expression profiling and laser capture microdissection have revealed that development and/or function of the fetal adrenal cortex may be regulated by a panoply of molecules, including transcription factors, extracellular matrix components, locally produced growth factors, and placenta-derived CRH, in addition to the primary regulator, fetal pituitary ACTH. The role of the fetal adrenal cortex in human pregnancy and parturition appears highly complex, probably due to redundant and compensatory mechanisms regulating these events. Mounting evidence indicates that actions of hormones operating in the human feto-placental unit are likely mediated by mechanisms including target tissue responsiveness, local metabolism, and bioavailability, rather than changes only in circulating levels. Comprehensive study of such molecular mechanisms and the newly identified factors implicated in adrenal development should help crystallize our understanding of the development and physiology of the human fetal adrenal cortex.

Follistatin as a potent regulator of bone metabolism

Follistatin is a monomeric glycoprotein, distributed in a wide range of tissues. Recent work has demonstrated that this protein is a pluripotential molecule that has no structural similarity but is functionally associated with members of the transforming growth factor (TGF)-β superfamily, which indicates its wide range of action. Members of the TGF-β superfamily, especially activins and bone morphogenetic proteins are involved in bone metabolism. They play an important role in bone physiology, influencing bone growth, turnover, bone formation and cartilage induction. As follistatin is considered to be the antagonist of the TGF-β superfamily members, it plays an important role in bone metabolism and development.

Cushing's syndrome and fetal features resurgence in adrenal cortex-specific Prkar1a knockout mice

Carney complex (CNC) is an inherited neoplasia syndrome with endocrine overactivity. Its most frequent endocrine manifestation is primary pigmented nodular adrenocortical disease (PPNAD), a bilateral adrenocortical hyperplasia causing pituitary-independent Cushing's syndrome. Inactivating mutations in PRKAR1A, a gene encoding the type 1 α-regulatory subunit (R1α) of the cAMP–dependent protein kinase (PKA) have been found in 80% of CNC patients with Cushing's syndrome. To demonstrate the implication of R1α loss in the initiation and development of PPNAD, we generated mice lacking Prkar1a specifically in the adrenal cortex (AdKO). AdKO mice develop pituitary-independent Cushing's syndrome with increased PKA activity. This leads to autonomous steroidogenic genes expression and deregulated adreno-cortical cells differentiation, increased proliferation and resistance to apoptosis. Unexpectedly, R1α loss results in improper maintenance and centrifugal expansion of cortisol-producing fetal adrenocortical cells with concomitant regression of adult cortex. Our data provide the first in vivo evidence that loss of R1α is sufficient to induce autonomous adrenal hyper-activity and bilateral hyperplasia, both observed in human PPNAD. Furthermore, this model demonstrates that deregulated PKA activity favors the emergence of a new cell population potentially arising from the fetal adrenal, giving new insight into the mechanisms leading to PPNAD.

Carney complex is a rare familial disease characterized by a predisposition to develop multiple endocrine tumors and highly morbid syndromes due to endocrine overactivities. Its most frequent endocrine manifestation, hypersecretion of glucocorticoids i.e. Cushing's syndrome, is caused by micronodular adrenal gland hyperplasia, an unusual neoplasia which combines both hyperplastic and atrophic areas. Inactivating mutations of the gene encoding the regulatory subunit 1α (R1α) of the cAMP–dependent protein kinase were frequently found in these patients, but the causal link between loss of R1α and onset of this adrenal disorder had not yet been established. Here, we describe the first mouse model mimicking this disease and provide mechanistic insights into endocrine overactivity and neoplastic transformation. Indeed, we show that lack of R1α induces autonomous expression of genes involved in steroid biosynthesis and resurgence of hyperplastic fetal-like cells with concomitant defects in cell renewal of the adult cortex. Our data therefore represent a substantial conceptual advance on the cellular dynamics involved in adrenal gland homeostasis. They suggest that regression of fetal structures may be important to establish normal endocrine functions and to allow cell renewal in the definitive cortex. Failure to clear out cells of fetal features in R1α-deficient adrenals leads to morbid hyperplasia.

Effects of continuous elevated cortisol concentrations during oestrus on concentrations and patterns of progesterone, oestradiol and LH in the sow

This study investigated the effect of continuous elevated cortisol concentrations during standing oestrus on time of ovulation and patterns of progesterone, oestradiol and luteinising hormone (LH) in sows. The elevation of cortisol concentrations was achieved through repeated intravenous injections of synthetic adrenocorticotropic hormone (ACTH) every 2 h for approximately 48 h, from the onset of the second standing oestrus after weaning. Treatment was terminated when ovulation was detected (monitored by transrectal ultrasonography every 4h) or when the sow had received a maximum of 24 injections. The dose of ACTH (2.5 microg/kg) was chosen to mimic the cortisol concentrations seen during mixing of unfamiliar sows. The sows (n=14) were surgically fitted with jugular vein catheters and randomly divided into a control (C group where only NaCl solution were injected) or an ACTH group. Blood samples were collected every 2 h. In parallel with the blood sampling, saliva samples for cortisol analyses were taken from eight sows before onset of treatment and from four of the sows during treatment. There was no difference in time from onset of standing oestrus to ovulation between the two groups. The interval between the peaks of oestradiol and LH to ovulation was prolonged in the ACTH group compared to the C group (p<0.05), with a tendency towards an earlier decline of oestradiol in the ACTH group. Cortisol and progesterone concentrations were significantly elevated during treatment in the ACTH group (p<0.001), with cortisol peak concentrations occurring between 40 and 80 min after each ACTH injection. Cortisol concentrations in saliva and plasma were highly correlated (p<0.001). In conclusion, elevated cortisol concentrations from the onset of standing oestrus increase progesterone concentrations and prolong the interval between oestradiol and LH peaks to ovulation, the latter possible due to an early decline in oestradiol concentrations and a change of the LH peak outline. The effect these hormonal changes have on reproductive performance need to be further investigated. Saliva samples might be a useful and non-invasive method to assess cortisol concentrations in sows.

Bone morphogenetic protein 7 is elevated in patients with chronic liver disease and exerts fibrogenic effects on human hepatic stellate cells

Hepatic stellate cells (HSCs) are the main extracellular matrix (ECM)-producing cells in liver fibrogenesis. The excessive synthesis of ECM proteins deteriorates hepatic architecture and results in liver fibrosis and cirrhosis. This study investigated the role of bone morphogenetic protein 7 (BMP7) as a member of the transforming growth factor (TGF)-beta superfamily in chronic liver disease. Plasma levels of BMP7 were significantly elevated in patients with chronic liver disease compared with healthy controls. Immunohistochemistry of cirrhotic human liver demonstrated upregulated BMP7 protein expression in hepatocytes as compared with normal human liver. Because gene expression for all putative BMP7 receptors was induced during the culture activation process of primary human HSCs, we studied the effects of BMP7 on hTERT immortalized human HSCs in vitro. BMP7, as expressed and secreted after infection with adenoviruses encoding BMP7 (AdBMP7), increased proliferation of HSCs. The mRNA and protein expression of type I collagen and fibronectin was increased in BMP7-stimulated HSCs. Elevated systemic and hepatic levels of BMP7 in patients with chronic liver disease may contribute to progression of liver fibrogenesis in vivo.

Transforming growth factor-beta blocks inhibin binding to different target cell types in a context-dependent manner through dual mechanisms involving betaglycan

Inhibin antagonizes activin and bone morphogenetic protein actions by sequestering their type II receptors in high-affinity complexes with betaglycan, a coreceptor that inhibin shares with TGF-beta. To clarify the nature and extent of interactions between inhibin and TGF-beta, we therefore examined 1) the mutual competition between these ligands for binding, 2) the regulation of endogenous betaglycan expression by inhibin and TGF-beta isoforms, and 3) the consequences of such betaglycan regulation for subsequent inhibin binding in mouse Leydig (TM3), Sertoli (TM4), adrenocortical cancer (AC), and gonadotroph (LbetaT2) cell lines, chosen to model cellular targets for local and endocrine actions of inhibin. Recognized inhibin, activin, and TGF-beta binding proteins and TGF-beta/activin signaling components were expressed by all four cell types, but AC and LbetaT2 cells notably lacked the type II receptor for TGF-beta, TbetaRII. Overnight treatment of TM3 and TM4 cells with TGF-beta1 suppressed the levels of betaglycan mRNA by 73 and 46% of control and subsequent [(125)I]inhibin A binding by 64 and 41% of control (IC(50) of 54 and 92 pm), respectively. TGF-beta2 acted similarly. TGF-beta pretreatments commensurately decreased the [(125)I]inhibin A affinity labeling of betaglycan on TM3 and TM4 cells. TGF-beta isoforms as direct competitors blocked up to 60% of specific inhibin A binding sites on TM3 and TM4 cells but with 9- to 17-fold lower potency than when acting indirectly via regulation of betaglycan. Only the competitive action of TGF-beta was observed with TbetaRII-deficient AC and LbetaT2 cells. Neither inhibin A nor inhibin B regulated betaglycan mRNA or competed for binding of [(125)I]TGF-beta1 or -beta2. Thus, inhibin binding to its target cell types is controlled by TGF-beta through dual mechanisms of antagonism, the operation of which vary with cell context and display different sensitivities to TGF-beta. In contrast, TGF-beta binding is relatively insensitive to the presence of either inhibin A or inhibin B.

Follistatin serum concentrations during full-term labour in women – significant differences between spontaneous and induced labour

Follistatin has been isolated from human placenta and has been identified in human foetal membranes and fluids. Serum follistatin levels in women rise during pregnancy particularly near term. In this study, we examined the effect of induction and stage of labour on maternal plasma concentrations of follistatin. Women who gave birth after a normal pregnancy were retrospectively divided into three groups: those who went in labour spontaneously (n= 33), needed induction by amniotomy and IV oxytocin (n= 18) or underwent planned caesarean section (n= 10). Serum was collected at 38–40 weeks of gestation, periodically through labour with a vaginal examination and once within 36 h postpartum and assayed for oestradiol, progesterone, prolactin and C-reactive protein. Follistatin was measured using a rabbit antiserum (#204) raised against purified 35 kDa bovine follistatin. Human recombinant follistatin was used as both standard and tracer. Concentrations of follistatin at 38–40 weeks of gestation were significantly different between groups. Those who had a spontaneous labour had concentrations higher than those who were induced. Similarly, those who were induced had concentrations higher than those who underwent a caesarean. In the spontaneous group, follistatin rose during labour, peaking at 57.9 ± 5.48 ng/ml at > 3 cm of cervical dilation, and after delivery follistatin decreased to 26.16 ± 3.4 ng/ml at 24 h post-delivery. In induced patients follistatin continued increasing to peak following delivery at 26.9 ± 3.0 ng/ml and decreased at > 3 h post-delivery. Follistatin concentrations in caesarean section patients at 24 h post-surgery (18.53 ± 3.74 ng/ml) were not different from that before the surgery and were comparable with the other two groups. Follistatin is clearly implicated in the onset of labour; however, further studies with a larger cohort of women are necessary to determine the nature of its role.

Expression of activin and inhibin subunits, receptors and binding proteins in human adrenocortical neoplasms

OBJECTIVE

The growth and differentiation factors activin and inhibin can affect tumour formation and steroid production in the adrenal cortex. These factors bind to type I (Alk-4), type II (ActRIIA, ActRIIB) and type III (betaglycan) receptors or to the activin-binding protein follistatin. Expression of these activin-related mRNAs was measured in different types of adrenocortical tissues and tumours to study the relationship with tumorigenesis.

DESIGN

Quantitative expression of activin-related mRNAs was investigated in patient adrenocortical samples.

PATIENTS

Twenty-eight human adrenocortical samples from normal and hyperplastic adrenals and from adrenocortical adenomas and carcinomas were collected after surgery for study purposes.

MEASUREMENTS

Using quantitative reverse transcription polymerase chain reaction (RT-PCR), we investigated the expression of inhibin alpha-, betaA- and betaB-subunits, follistatin, betaglycan, ActRIIA, ActRIIB and Alk-4 in the adrenocortical tissues. The expression of cytochrome P450c17 (CYP17) mRNA was also measured to investigate its association with inhibin and activin subunit expression.

RESULTS

All genes studied were expressed in all tissues, with the exception of the inhibin alpha-subunit in one hyperplastic adrenal and three adrenocortical carcinomas. Expression of inhibin betaA-subunit, follistatin, betaglycan, ActRIIA, ActRIIB and CYP17 differed between nontumorous adrenals and carcinomas.

CONCLUSIONS

These differences, together with correlation analysis, indicate parallel regulation of the expression of CYP17, the inhibin alpha-subunit, ActRIIA, ActRIIB, betaglycan and follistatin. We conclude that the expression of activin and inhibin subunits, receptors and binding proteins is affected by tumour formation in the adrenal gland and may play a role in tumorigenesis.

Functional genomics approaches for the study of sporadic adrenal tumor pathogenesis: clinical implications

Although sporadic adrenal tumors are frequently encountered in the general population their pathogenesis is not well elucidated. The advent of functional genomics/bioinformatics tools enabling large scale comprehensive genome expression profiling should contribute to significant progress in this field. Some studies have already been published describing gene expression profiles of benign and malignant adrenocortical tumors and phaeochromocytomas. Several genes coding for growth factors and their receptors, enzymes involved in steroid hormone biosynthesis, genes related to the regulation of cell cycle, cell proliferation, adhesion and intracellular metabolism have been found to be up- or downregulated in various tumors. Some alterations in gene expression appear so specific for certain tumor types that their application in diagnosis, determination of prognosis and the choice of therapy can be envisaged. In this short review, the authors will present a synopsis of these recent findings that seem to open new perspectives in adrenal tumor pathogenesis, with emphasis on changes in steroidogenic enzyme expression profiles and highlighting possible clinical implications.

An Inhibin B and Estrogen-Secreting Adrenocortical Carcinoma Leading to Selective FSH Suppression

OBJECTIVE

Hormone-secreting adrenocortical tumors are frequently associated with endocrine syndromes. We describe a 30-year-old man who had abdominal pain, a nodule in the right breast and loss of libido. Abdominal magnetic resonance imaging revealed a very large tumor in the right adrenal gland.

METHODS

Hormonal profile disclosed increased levels of estradiol and slightly low testosterone levels. The basal and stimulated LH levels were normal, whereas basal and stimulated FSH levels were totally suppressed. Cortisol and adrenal androgen levels were normal. The unusual finding of selective FSH suppression suggested secretion of inhibin B by the adrenocortical tumor. A very high level of serum inhibin B (405 pg/ml) was demonstrated by ELISA assay. Right adrenalectomy and nephrectomy were performed and the tumor was classified as a malignant tumor (Weiss score: 7.0) and unilateral mastectomy disclosed a lipoma.

RESULTS

One week after surgery, a GnRH-stimulation test disclosed normal basal and stimulated FSH levels and low levels of inhibin B and estradiol. Immunohistochemical analysis with anti-B-inhibin antibody revealed intense staining in the adrenocortical tumor cells. One month after surgery, an abdominal magnetic resonance imaging revealed a local recurrence of the tumor and a second surgery was performed with partial resection of the tumor and the patient died 1 year after the first surgery.

CONCLUSION

We herein report the first inhibin B and estradiol-secreting adrenocortical carcinoma. The unusual selective inhibition of FSH secretion should be considered a valuable hormonal finding for the diagnosis of inhibin B-secreting adrenocortical tumors.

[Molecular mechanisms involved in adrenocortical tumorigenesis]

The adrenocortical tumorigenesis is a complex process, which involves multiple genetic changes. A better knowledge on the mechanisms involved in tumor development would enable an early identification of malignant disease and also lead to the development of new treatment strategies. Although in the recent years a large amount of data was produced, the exact mechanisms that lead to adrenocortical tumor development remains poorly understood. Most of the studies produced were based on the candidate-gene strategy, which has its own limitations. A genome-wide approach, such as microarrays, will surely shed some light into the mechanisms responsible for adrenocortical tumorigenesis. In this review, we summarize the most recent data available on this complex process.

Diverse biological effect and Smad signaling of bone morphogenetic protein 7 in prostate tumor cells

We found that bone morphogenetic protein (BMP) 7, a member of the BMP family, was strikingly up-regulated during the development of primary prostatic adenocarcinoma in the conditional Pten deletion mouse model. To determine the relevance of this finding to human prostate cancer, we examined the expression of BMPs and BMP receptors (BMPR) as well as the responsiveness to recombinant human BMP7 in a series of human prostate tumor cell lines. All prostatic cell lines tested expressed variable levels of BMP2, BMP4, and BMP7 and at least two of each type I and II BMPRs. In all cases, BMP7 induced Smad phosphorylation in a dose-dependent manner, with Smad5 activation clearly demonstrable. However, the biological responses to BMP7 were cell type specific. BPH-1, a cell line representing benign prostatic epithelial hyperplasia, was growth arrested at G1. In the bone metastasis-derived PC-3 prostate cancer cells, BMP7 induced epithelial-mesenchymal transdifferentiation with classic changes in morphology, motility, invasiveness, and molecular markers. Finally, BMP7 inhibited serum starvation-induced apoptosis in the LNCaP prostate cancer cell line and more remarkably in its bone metastatic variant C4-2B line. Each of the cell lines influenced by BMP7 was also responsive to BMP2 in a corresponding manner. The antiapoptotic activity of BMP7 in the LNCaP and C4-2B cell lines was not associated with a significant alteration in the levels of the proapoptotic protein Bax or the antiapoptotic proteins Bcl-2, Bcl-xl, and X-linked inhibitor of apoptosis. However, in C4-2B cells but not in LNCaP cells, a starvation-induced decrease in the level of survivin was counteracted by BMP7. Taken together, these findings suggest that BMPs are able to modulate the biological behavior of prostate tumor cells in diverse and cell type-specific manner and point to certain mechanisms by which these secreted signaling molecules may contribute to prostate cancer growth and metastasis.

Functional biology of the primate fetal adrenal gland: advances in technology provide new insight

1. The main aim of the present review is to summarize recent experimental data from human and non-human primate models that have identified factors essential for adrenal development and other factors that may determine the regulation of the specific structural organization and function of the adrenal gland. 2. The fetal adrenal cortex has two morphologically distinct zones, with the outer definitive zone being comprised of tightly packed small cells, which appear to be steroidogenically quiescent until late gestation, and the inner fetal zone, which appears to be steroidogenically active throughout gestation. 3. In the primate fetus, growth of the adrenal gland involves hyperplasia, hypertrophy, migration and senescence. Cells appear to proliferate in the external portion of the definitive zone and then move centripetally and become non-proliferative in the fetal zone, where they acquire their steroidogenic capacities. 4. A variety of new technologies has been used to identify zonal-specific markers of the cortical zones within the developing human fetal adrenal gland. On microarray, 67 transcripts showed a minimum of a 2.5-fold difference between the fetal and adult adrenal gland. The vast majority of these genes had not been studied in relation to adrenal gland development or function. In combination with techniques such as laser capture microdissection, which has allowed the isolation of fairly pure zone-specific cell populations from the human fetal adrenal cortex, we can begin to unravel the complex interactions regulating adrenal growth and functional differentiation.

Novel action of activin and bone morphogenetic protein in regulating aldosterone production by human adrenocortical cells

We have uncovered a functional bone morphogenetic protein (BMP) and activin system complete with ligands (BMP-6 and activin betaA/betaB), receptors (activin receptor-like kinase receptors 2, 3, and 4; activin type-II receptor; and BMP type-II receptor), and the binding protein follistatin in the human adrenocortical cell line H295R. Administration of activin and BMP-6 to cultures of H295R cells caused concentration-responsive increases in aldosterone production. The mRNA levels of steroidogenic acute regulatory protein or P450 steroid side-chain cleavage enzyme, the rate-limiting steps of adrenocortical steroidogenesis, were enhanced by activin and BMP-6. Activin and BMP-6 also activated the transcription of steroidogenic acute regulatory protein as well as the late-step steriodogenic enzyme CYP11B2. Activin enhanced ACTH-, forskolin-, or dibutyryl-cAMP- but not angiotensin II (Ang II)-induced aldosterone production, whereas BMP-6 specifically augmented Ang II-induced aldosterone production. Activin and ACTH but not BMP-6 increased cAMP production. Follistatin, which inhibits activin actions by binding, suppressed basal and ACTH-induced aldosterone secretion but failed to affect the Ang II-induced aldosterone level. Furthermore, MAPK signaling appeared to be involved in aldosterone production induced by Ang II and BMP-6 because an inhibitor of MAPK activation, U0126, reduced the level of aldosterone synthesis stimulated by Ang II and BMP-6 but not activin. In addition, Ang II reduced the expression levels of BMP-6 but increased that of activin betaB, whereas ACTH had no effect on these levels. Collectively, the present data suggest that activin acts to regulate adrenal aldosterone synthesis predominantly by modulating the ACTH-cAMP-protein kinase A signaling cascade, whereas BMP-6 works primarily by modulating the Ang II-MAPK cascade in human adrenal cortex in an autocrine/paracrine fashion.

Ovarian regulation of endometrial gland morphogenesis and activin-follistatin system in the neonatal ovine uterus

Postnatal development of the ovine uterus between birth and Postnatal Day (PND) 56 involves differentiation of the endometrial glandular epithelium from the luminal epithelium followed by tubulogenesis and branching morphogenesis. Previous results indicated that ovariectomy of ewes at birth did not affect uterine growth or initial stages of endometrial gland genesis on PND 14 but did affect uterine growth after PND 28. Available evidence from a number of species supports the hypothesis that the ovary does not affect endometrial gland morphogenesis in the postnatal uterus. To test this hypothesis in our sheep model, ewes were assigned at birth to a sham surgery as a control or bilateral ovariectomy (OVX) on PND 7. Uteri were removed and weighed on PND 56. Ovariectomy did not affect circulating levels of estradiol-17beta. Uterine weight was 52% lower in OVX ewes. Histomorphological analyses indicated that the thickness of the endometrium and myometrium, total number of endometrial glands, and endometrial gland density in the stratum spongiosum stroma was reduced in uteri of OVX ewes. In contrast, the number of superficial ductal gland invaginations and gland density in the stratum compactum stroma was not affected by ovariectomy. The uteri of OVX ewes contained lower levels of betaA subunit, activin receptor (ActR) type IA, ActRIB, and follistatin protein expression but higher levels of betaB subunit. In the neonatal ovary, follistatin, inhibin alpha subunit, betaA subunit, and betaB subunit were expressed in antral follicles between PNDs 0 and 56. These results led to rejection of the hypothesis that the ovary does not influence endometrial adenogenesis. Rather, the ovary and, thus, an ovarian-derived factor regulates, in part, the coiling and branching morphogenetic stage of endometrial gland development after PND 14 and expression of specific components of the activin-follistatin system in the neonatal ovine uterus that appear to be important for that critical process.