Novel medical therapies for pituitary tumors.

Despite considerable progress, there is still no medical treatment available for some kinds of pituitary tumors, in particular hormone inactive adenomas and corticotroph pituitary tumors. Surgical removal or at least debulking of the tumor is the only option to treat these kinds of tumors apart from rarely applied radiotherapy. Moreover, treatment resistance is present in a considerable proportion of patients bearing pituitary tumors, for which medical treatment regimens are already available (prolactinomas, somatotroph adenomas). Thus, novel or improved medical treatment strategies would be desirable. Here, we summarize preclinical and clinical findings about the hormone and growth-suppressive action of various drugs, which will probably lead to novel future medical treatment concepts for pituitary tumors.

A standardised diagnostic approach to pituitary neuroendocrine tumours (PitNETs): a European Pituitary Pathology Group (EPPG) proposal.

The 2017 World Health Organization (WHO) classification proposes to type and subtype primary adenohypophyseal tumours according to their cell lineages with the aim to establish more uniform tumour groups. The definition of atypical adenoma was removed in favour of high-risk adenoma, and the assessment of proliferative activity and invasion was recommended to diagnose aggressive tumours. Recently, the International Pituitary Pathology Club proposed to replace adenoma with the term of pituitary neuroendocrine tumour (PitNET) to better reflect the similarities between adenohypophyseal and neuroendocrine tumours of other organs. The European Pituitary Pathology Group (EPPG) endorses this terminology and develops practical recommendations for standardised reports of PitNETs that are addressed to histo- and neuropathologists. This brief report presents the results of EPPG's consensus for the reporting of PitNETs and proposes a diagnostic algorithm.

Retinoic acid prevents experimental Cushing syndrome.

Cushing syndrome is caused by an excess of adrenocorticotropic hormone (ACTH) production by neuroendocrine tumors, which subsequently results in chronic glucocorticoid excess. We found that retinoic acid inhibits the transcriptional activity of AP-1 and the orphan receptors Nur77 and Nurr1 in ACTH-secreting tumor cells. Retinoic acid treatment resulted in reduced pro-opiomelanocortin transcription and ACTH production. ACTH inhibition was also observed in human pituitary ACTH-secreting tumor cells and a small-cell lung cancer cell line, but not in normal cells. This correlated with the expression of the orphan receptor COUP-TFI, which was found in normal corticotrophs but not in pituitary Cushing tumors. COUP-TFI expression in ACTH-secreting tumor cells blocked retinoic acid action. Retinoic acid also inhibited cell proliferation and, after prolonged treatment, increased caspase-3 activity and induced cell death in ACTH-secreting cells. In adrenal cortex cells, retinoic acid inhibited corticosterone production and cell proliferation. The antiproliferative action and the inhibition of ACTH and corticosterone produced by retinoic acid were confirmed in vivo in experimental ACTH-secreting tumors in nude mice. Thus, we conclude that the effects of retinoic acid combine in vivo to reverse the endocrine alterations and symptoms observed in experimental Cushing syndrome.

New aspects in the diagnosis and treatment of Cushing disease.

Cushing disease, which is caused by the excessive production of ACTH, is a rare and complex endocrine disorder that still represents a major challenge for the physician in terms of accurate diagnosis and efficient treatment. Diagnosing Cushing syndrome and its etiology is an elaborate procedure and no single test is sensitive and specific enough to provide sufficient accuracy. Therefore, an ordered cascade of tests is necessary recommended by a consensus statement in 2002. The proposed diagnostic algorithm will be summarized in the following section. In the absence of efficient drug therapy, transsphenoidal resection of the pituitary adenoma is the treatment of choice for the reduction of ACTH secretion. However, not all patients can be cured by surgery. In the present article, we examine recent studies that have investigated the therapeutic potential of new generations of drugs for the treatment of Cushing disease such as cabergoline and SOM230. The role of nuclear receptors: retinoic acid receptors and peroxisome proliferator-activated receptor-gamma as new approaches for treating pituitary tumors is also discussed.

The expression of the antiproliferative gene ZAC is lost or highly reduced in nonfunctioning pituitary adenomas.

The ZAC gene encodes a new zinc-finger protein that concomitantly induces apoptosis and cell cycle arrest and localizes to chromosome 6q24-q25, a well-known hot spot related to cancer. ZAC is highly expressed in the anterior pituitary gland, and its ablation by antisense targeting promotes pituitary cell proliferation. Here we investigate ZAC status in pituitary tumors to evaluate its role in pituitary tumorigenesis. Interest ingly, a strong reduction or absence of ZAC mRNA and protein expres sion was detected in nonfunctioning pituitary adenomas, whereas in clin ically active pituitary neoplasias, the decrease in ZAC expression was variable. Loss of expression was not associated with a mutation of the ZAC gene. Our observations suggest that alternative mechanisms of gene inactivation and/or altered regulation of the ZAC gene occur in nonfunctioning pituitary adenomas.

Clinical Impact of the Current WHO Classification of Pituitary Adenomas.

WHO classifications should be used for comparing the results from different groups of pathologist and clinicians by standardized histopathological methods. Our present report describes the important parameters of pituitary adenoma pathology as demand of the WHO classification for correlation to endocrine data and prognosis. The combination of HE stain based structures with immunostainings for pituitary hormones allows subclassification of adenomas as the best method not only for correlations to clinical hyperfunctions but also for statements to the sensitivity of drug therapies (somatostatin analogs, dopamine agonists). GH-, PRL- and ACTH-secreting pituitary adenomas are further classified based on the size and number of their secretory granules by electron microscopy, or as is mostly the case nowadays by cytokeratin staining pattern, into densely and sparsely granulated. Granulation pattern may be considered for the prediction of treatment response in patients with GH-secreting adenomas, since the sparsely granulated subtype was shown to be less responsive to somatostatin analog treatment. For prognosis, it is important to identify aggressive adenomas by measurements of the Ki-67 index, of the number of mitoses, and of nuclear expression of p53. Among the criteria for atypical adenomas, high Ki-67 labeling index and invasive character are the most important adverse prognostic factors. Promising molecular markers have been identified that might supplement the currently used proliferation parameters. For defining atypical adenomas in a future histopathological classification system, we propose to provide the proliferative potential and the invasive character separately.

Emerging Histopathological and Genetic Parameters of Pituitary Adenomas: Clinical Impact and Recommendation for Future WHO Classification.

The review assesses immunohistochemical findings of somatostatin receptors and of metalloproteinases in different pituitary adenoma types and the significance of molecular genetic data. Current evidence does not support routine immunohistochemical assessment of somatostatin or dopamine receptor subtype expression on hormone-secreting or nonfunctioning pituitary adenomas. Further prospective studies are needed to define its role for clinical decision making. Until then we suggest to restrict membrane receptor profiling to individual cases or for study purposes. The problems of adenoma expansion and invasion are discussed. Despite partially contradictory publications, proteases clearly play a major role in permission of infiltrative growth of pituitary adenomas. Therefore, detection of at least MMP-2, MMP-9, TIMP-2, and uPA seems to be justified. Molecular characterization is important for familial adenomas, adenomas in MEN, Carney complex, and McCune-Albright syndrome and can gain insight into pathogenesis of sporadic adenomas.

Bacterial endotoxin (lipopolysaccharide) stimulates interleukin-6 production and inhibits growth of pituitary tumour cells expressing the toll-like receptor 4.

Members of the Toll receptor (Tlr) family have a crucial role in the innate immune response following bacterial infection. The effects of Gram-negative bacteria-derived endotoxins (lipopolysaccharide, LPS) are predominantly mediated by Tlr4, and we have recently shown that pituitary folliculostellate cells express functional Tlr4. In the present study, we investigated whether Tlr4 is also present in normal and transformed endocrine epithelial pituitary cell types. By reverse transcriptase-polymerase chain reaction, Tlr4 mRNA expression was found in some pituitary epithelial tumour cell lines (AtT20, HP75), whereas others were negative (GH3, alphaT3-1). Tlr4 protein was detected by immunohistochemistry in a few epithelial cells in normal human anterior pituitaries and in 26 out of 67 human pituitary tumours analysed. LPS had no effect on adrenocorticotropic hormone secretion in Tlr4-positive AtT20 cells, but it suppressed the growth of these cells in a dose-dependent manner. As expected, neither hormone secretion, nor growth of Tlr4-negative GH3 cells was affected by LPS. In cell cultures of Tlr4-positive pituitary adenomas, LPS dose-dependently stimulated the production of interleukin (IL)-6, which is known to induce growth and hormone production in pituitary tumours. The LPS-induced IL-6 production was blocked by the specific p38alphaMAP kinase inhibitor, SB203580, and by the synthetic glucocorticoid, dexamethasone. The data suggest that, during Gram-negative bacteria-induced infections or inflammatory processes, LPS could affect pituitary tumour pathophysiology and progression in the subset of Tlr4-expressing pituitary adenomas.

Autocrine IL-2-dependent growth of a newly established CD3+, CD16-, CD56+, CD57+, J(H)-, TCRbeta-, TCRgamma- leukemia cell line (NOI-90).

Leukemic cells from a 45-year-old male patient with a CD3+, CD56+, CD57+, CD7+ acute lymphoblastic leukemia were cultured in vitro in the absence of any added growth factor for up to 6 years and a continuous lymphoblastoid cell line (NOI-90) was established. NOI-90 cells have the same phenotype and karyotype as initial leukemic cells. Southern blot of DNA from NOI-90 cells showed that TCRbeta, TCRgamma, and J(H) were in germ line. Two and 25% of NOI-90 cells were positive when stained with the IOT14 and 7G7/B6 moAbs, which recognize the CD25 molecule (IL-2R alpha chain); moreover, 4% and 13% of the cells were positive when stained with the TU-27 and mik beta3 moAbs which recognize the CD122 molecule (IL-2Rbeta chain). Equilibrium binding experiments with radiolabelled IL-2 revealed the presence of a small number of high affinity IL-2R on both fresh and continuously growing cells. Media conditioned by NOI-90 cells could induce proliferation of an IL-2-dependent cell line and this IL-2 activity could be detected by a sensitive immunoenzymatic assay using antibodies recognizing distinct epitopes of IL-2. Moreover, IL-2 activity could be adsorbed by immunoaffinity on anti-IL-2 polyclonal purified IgG and the retained molecule displayed a m.w. of 14.5 kDa in SDS-PAGE. In addition, IL-2 immunoreactive molecules could be revealed in the cytoplasm of the cells. Finally, IL-2 fixed on the cell membrane could be detected by indirect immunofluorescence. Although added IL-2 could not induce cell proliferation, monoclonal antibodies against CD25, CD122 and IL-2 could specifically inhibit spontaneous cell proliferation in a dose-dependent manner. NOI-90 cells failed to demonstrate any cytotoxic activity against the K-562, Raji or Daudi cells. These findings indicate that NOI-90 cells are of non-T, non-B, origin lacking NK activity but proliferate under an autocrine pathway which involves, at least partly, the IL-2/IL-2R system.

Large-scale effects on resistivity index of porous media.

The estimation of humidity in the unsaturated zone of soils and NAPL saturation in contaminated aquifers may be based on the interpretation of electrical resistivity index logs. In the present work, concepts of the theory of the two-phase flow in pore networks are employed to interpret the form of the equilibrium and dynamic resistivity index curves of large porous samples. A resistivity cell is constructed to measure the capillary and electrical properties of large samples of unconsolidated porous media. The drainage capillary pressure and resistivity index curves of a sand column are measured by using the micropore membrane (porous plate) method, where a 0.5% wt/vol NaCl aqueous solution is displaced by n-dodecane. The dynamic resistivity index curves are measured by using the continuous injection technique for various orientations of the sand column. Based on concepts of the two-phase flow theory, concerning the dominant displacement growth pattern in a pore network and arising from the cooperative effects of capillary, buoyancy, and viscous forces, approximate relationships are developed for the resistivity index and saturation exponent as functions of the water saturation. The saturation exponent decreases as the displacement advances and the fluid distribution across the sand column tends to be homogenized after oil breakthrough. Both the resistivity index and saturation exponent increase as the displacement pattern tends to become compact and stable. In the destabilized flow pattern, as the Bond number decreases, the resistivity index may increase respectably within a narrow range of values of the Bond number. This happens when the thickness of the unstable capillary finger exceeds the lateral dimension of the porous sample and becomes a fractal percolation cluster. The saturation exponent becomes almost constant and independent of water saturation only over the destabilized displacement pattern at high values of the Bond number.

Differential expression of menin in sporadic pituitary adenomas.

Pituitary adenomas represent one of the key features of multiple endocrine neoplasia type 1. The gene involved in this syndrome (MEN1) is a putative tumor suppressor, that codes for a 610-amino acid nuclear protein termed 'menin'. Analyses of sporadic pituitary adenomas have so far failed to reveal MEN1 mutations or defects in MEN1 transcription in these tumors. In the present study we detected menin protein expression in a panel of normal and tumoral pituitary tissues, using a monoclonal antibody against the carboxy-terminus of menin. In the normal human pituitary gland, strong nuclear staining for menin was detectable in the majority of the endocrine cells of the anterior lobe, without a clear association with a particular hormone-producing type. In sporadic pituitary adenomas, menin expression was variable, with a high percentage of cases demonstrating a significant decrease in menin immunoreactivity when compared with the normal pituitary. Interestingly, metastatic tissues derived from one pituitary carcinoma had no detectable menin levels. Altogether, our data provide the first information regarding the status of menin expression in human normal and neoplastic pituitary as determined by immunohistochemistry (IHC).

Normal human pituitary gland and pituitary adenomas express cannabinoid receptor type 1 and synthesize endogenous cannabinoids: first evidence for a direct role of cannabinoids on hormone modulation at the human pituitary level.

Little is known about the expression and function of cannabinoid receptor type 1 (CB1) in the human pituitary gland. The aim of this study was to investigate CB1 expression in human normal and tumoral pituitaries by in situ hybridization and immunohistochemistry using an antibody against CB1. CB1 was found in corticotrophs, mammotrophs, somatotrophs, and folliculostellate cells in the anterior lobe of normal pituitary. After examination of 42 pituitary adenomas, CB1 was detected in acromegaly-associated pituitary adenomas, Cushing's adenomas, and prolactinomas, whereas faint or no expression was found in nonfunctioning pituitary adenomas. Experiments with cultured pituitary adenoma cells showed that the CB1 agonist WIN 55,212--2 inhibited GH secretion in most of acromegaly-associated pituitary adenomas tested and that the CB1 antagonist SR 141716A was generally able to reverse this effect. Moreover, WIN 55,212--2 was able to suppress GHRH-stimulated GH release, and this effect was not blocked by coincubation with SR 141716A, possibly indicating a non-CB1-mediated effect. In contrast, WIN 55,212--2 was ineffective on GH-releasing peptide-stimulated GH release. In four Cushing's adenomas tested, WIN 55,212--2 was not able to modify basal ACTH secretion. However, simultaneous application of CRF and WIN 55,212--2 resulted in a synergistic effect on ACTH secretion, and this effect could be abolished by SR 141716A, demonstrating a CB1-mediated effect. In the single case of prolactinomas tested, WIN 55,212--2 was able to inhibit basal secretion of PRL. Finally, the presence of endocannabinoids (anandamide and 2-arachidonoylglycerol) was investigated in normal and tumoral pituitaries. All tumoral samples had higher contents of anandamide and 2-arachidonoylglycerol compared with the normal hypophysis. Moreover, endocannabinoid content in the different pituitary adenomas correlated with the presence of CB1, being elevated in the tumoral samples positive for CB1 and lower in the samples in which no or low levels of CB1 were found. The results of this study point to a direct role of cannabinoids in the regulation of human pituitary hormone secretion.

Thyrotropin-releasing hormone time-dependently influences thyrotropin microheterogeneity--an in vivo study in euthyroidism.

Thyrotropin (TSH) is secreted not as one distinct hormone, but rather as a group of isohormones which differ in their oligosaccharide composition. Although the mechanisms regulating TSH glycosylation are not fully understood, there is strong evidence that TRH plays an important role. The aim of our study was to determine the dynamic influence of TRH on TSH microheterogeneity. Sera were obtained from euthyroid volunteers (n=20) before and 30, 60, 120, 180 and 240 min after intravenous, nasal and oral administration of TRH in three independent runs (randomized order, at a time-interval of 3 weeks between each run). TSH was immuno-concentrated and analysed by isoelectric focusing (IEF) and lentil lectin affinity chromatography. TSH immunoreactivity was measured by an automated second-generation TSH immunoassay. Overall, serum TSH concentrations reached maximal values 30 min after intravenous, 60 min after nasal and 180 min after oral TRH stimulation. IEF analysis revealed 63.3+/-3.3% of pituitary standard TSH (IRP 80/558) in the neutral pH range (8>pH>6). In contrast, 30 min after TRH stimulation 80.8+/-3.7% (P<0.001) and 60 min after TRH stimulation 44.9+/-2.2% (P<0.001) of the TSH of euthyroid probands were found in this pH range, whereas 180 min after TRH stimulation 58.4+/-2.3% (P<0.001) were detected in the acidic pH range (pH<6). This shift of TSH composition in euthyroidism after TRH stimulation was confirmed by lentil lectin analysis of TSH: core-fucose content of euthyroid TSH was 73.4+/-3.8% 30 min and 22.9+/-3.2% 120 min after TRH stimulation in contrast to basal (53.3+/-1.8%; P<0.001) and pituitary standard (IRP 80/558) TSH (63.0+/-0.9%; P<0.001). In conclusion, in euthyroidism, TRH stimulation time-dependently changes the distribution pattern of the TSH isoforms from an alkaline and neutral to a more acidic one. This corresponds to the secretion of isohormones with altered bioactivity which could influence the fine-tuning of thyroid function.

Modulation of human thyrotropin oligosaccharide structures--enhanced proportion of sialylated and terminally galactosylated serum thyrotropin isoforms in subclinical and overt primary hypothyroidism.

Enhanced sialylation of thyrotropin (TSH) prolongs its metabolic clearance rate and thus increases the hormone's in vivo bioactivity. This has been shown for hypothyroid rats and for recombinant human TSH, but there are few data on the sialylation of human serum TSH. The aim of this work was to further study sialylated human serum TSH, its precursors bearing terminal galactose residues, and the role of pharmacological doses of thyrotropin-releasing hormone (TRH) on their secretion under different degrees of primary hypothyroidism. We analyzed serum TSH in patients with subclinical (n = 9) and overt primary hypothyroidism (n = 13) compared with euthyroid individuals (n = 12) and human standard pituitary TSH (IRP 80/558). Blood was drawn before and 30 min after intravenous administration of 200 micrograms TRH, and TSH was purified by immunoaffinity concentration. The content of sialylated (sialo-) TSH and isoforms bearing terminal galactose (Gal-TSH, asialo-Gal-TSH) was measured by Ricinus communis (RCA 120) affinity chromatography in combination with enzymatic cleavage of sialic acid residues. TSH immunoreactivity was measured by an automated second generation TSH immunoassay. Pituitary TSH contained 16.5 +/- 0.8% Gal-TSH. In euthyroid individuals the proportion of Gal-TSH was 14.6 +/- 1.9%, whereas TSH in patients with subclinical and overt primary hypothyroidism contained 23.9 +/- 3.5% (P < 0.05 vs euthyroid individuals) and 21.1 +/- 1.7% Gal-TSH respectively. The mean ratio of asialo-Gal TSH was 23.8 +/- 0.6% for pituitary TSH, 35.7 +/- 4.2% in euthyroid individuals, 48.0 +/- 3.3% in patients with subclinical, and 61.5 +/- 3.8% (P < 0.001 vs euthyroid individuals) in patients with overt primary hypothyroidism. For pituitary TSH the calculated proportion of sialo-TSH was 6.5 +/- 0.2%, for euthyroid individuals 20.3 +/- 2.8%, for patients with subclinical hypothyroidism 24.1 +/- 3.0%, and for patients with overt primary hypothyroidism 40.7 +/- 3.0% (P < 0.001 vs euthyroid individuals). The proportions of Gal-TSH, asialo-Gal-TSH, and sialo-TSH did not differ significantly before and after TRH administration in the individuals studied. Our data show that patients with subclinical and overt primary hypothyroidism have a markedly increased proportion of serum TSH isoforms bearing terminal galactose and sialic acid residues, which may represent a mechanism for the further stimulation of thyroid function. Pharmacological doses of TRH cause an increased quantity of TSH to be released, but do not significantly alter the proportion of sialylated or terminally galactosylated TSH isoforms.

Thyrotrophin receptor protein expression in normal and adenomatous human pituitary.

Thyrotrophin (TSH) synthesis and secretion is under the positive control of thyrotrophin releasing hormone and under the negative control of the thyroid hormones. However, it is hypothesised that TSH has a direct effect on the regulation of its own synthesis through an intrapituitary loop mediated by pituitary TSH receptors (TSH-R). The aim of this investigation was to study the expression of TSH-R in normal human pituitary at mRNA and protein levels, and to compare the pattern of protein expression between different pituitary adenomas. Using RT-PCR we were able to detect TSH-R mRNA in the normal pituitary, and immunohistochemical studies showed TSH-R protein expression in distinct areas of the anterior pituitary. Double immunostaining with antibodies against each of the intrapituitary hormones and S100 revealed that TSH-R protein is present in thyrotrophs and folliculostellate cells. Examination of 58 pituitary adenomas, including two clinically active and two clinically inactive thyrotroph adenomas, revealed TSH-R immunopositivity in only the two clinically inactive thyrotroph adenomas. This study shows, for the first time, the presence of TSH-R protein in the normal anterior pituitary and in a subset of thyrotroph adenomas. The expression of TSH-R in the thyrotroph and folliculostellate cell subpopulations provides preliminary evidence of a role for TSH in autocrine and paracrine regulatory pathways within the anterior pituitary gland.

Expression of epidermal growth factor receptor in neoplastic pituitary cells: evidence for a role in corticotropinoma cells.

The oncogenic effects of epidermal growth factor (EGF) have long been established. EGF receptor (EGFr) is overexpressed in many types of tumors and constitutes a target for cancer treatment. The pituitary gland is a target of EGF action and it is very likely that EGFr plays a role in pituitary tumor formation and progression. However, there is a controversy in the literature concerning EGFr expression in the different types of pituitary adenomas. In the present study we investigated the expression pattern of the wild type EGFr (EGFrWT) and the constitutively active variant III (EGFrvIII) at the mRNA and protein levels in a large series of pituitary tumors. EGFrWT was found in a high percentage of hormone-secreting tumors, but only in a small fraction of non-functioning pituitary adenomas, while no expression of the EGFrvIII could be detected by nested RT-PCR in any tumor. Among the hormone-secreting adenomas, the highest incidence of EGFr expression was found in Cushing's pituitary adenomas. Furthermore, immunohistochemistry for the phosphorylated EGFr revealed the presence of activated EGFr in most Cushing's adenomas, compared with most pituitary adenomas. Taking into account that downregulation of p27/Kip1 plays a significant role in corticotrope tumorigenesis and that EGFr mitogenic signaling results in decreased p27/Kip1, we searched for a correlation between EGFr expression and p27/Kip1 levels in corticotropinomas. Low p27/Kip1 immunoreactivity was observed in corticotropinomas expressing EGFr. On the other hand, somatotropinomas expressing EGFr had high p27/Kip1 immunoreactivity. These data suggest a corticotrope-specific phenomenon and indicate that EGFr may have a role in the unbalanced growth of corticotrope tumoral cells.

Laminin inhibits lactotroph proliferation and is reduced in early prolactinoma development.

Laminin is a component of the extracellular matrix (ECM) that regulates cell proliferation and hormone secretion. Here we describe the effects of laminin on prolactin secretion in normal and tumor cells and analyze laminin expression pattern during prolactinoma development. Prolactin secretion and cell proliferation were inhibited by laminin in GH3 cells. In contrast, no effect was observed in normal pituitary cells. Laminin showed a dynamic expression pattern during prolactinoma development, which was: (a) strong in normal pituitaries from wild type or dopamine D2 receptor deficient mice, (b) lower in pituitary hyperplasia and (c) markedly reduced in prolactinomas from D2R -/- mice. A similar gradual decrease in laminin was found by comparing normal human pituitaries, human pituitary hyperplasia and human prolactinomas. These results show dynamic changes of laminin expression during prolactinoma formation which, due to laminin action on PRL production and cell proliferation, indicate a possible role for laminin in prolactinoma development.

Retention of dopamine 2 receptor mRNA and absence of the protein in craniospinal and extracranial metastasis of a malignant prolactinoma: a case report.

OBJECTIVES: The case presented here describes the clinical evolution of a malignant prolactinoma with occurrence of intra- and extra-cranial metastases. In this case, the presence of dopamine 2 receptor (D2R) was studied at the mRNA and protein level, in order to understand the pathological background of the resistance to treatment with different dopamine agonists. DESIGN: Together with an extensive description of the clinical history of this case, a combination of in vitro and in vivo techniques was performed to provide the basis of the dopamine resistance developed in the course of the disease. METHOD: A comparison of the D2R was performed in specimens obtained at presentation of the disease compared with autoptic specimens derived from local invasion and metastasis using in situ hybridization and immunohistochemical techniques. RESULTS: Intact D2R mRNA was found in the primitive tumor and metastatic tissues, whereas protein for the same receptor was present only in the tissues derived from neurosurgical operations and not in the metastases obtained post-mortem. CONCLUSION: This is the first report of the absence of D2R protein despite the retention of the transcript in an advanced stage of a malignant prolactinoma. The findings of this single case suggest the hypothesis that postranscriptional mechanisms may contribute to the development of dopamine resistance in prolactinomas.

The antiglucocorticoid RU486 downregulates the expression of interleukin-2 receptors in normal human lymphocytes.

The effects of the antiglucocorticoid RU486 on the expression of low and high affinity interleukin-2 receptors (IL-2R) in phytohaemagglutinin (PHA)-activated human peripheral blood lymphocytes were investigated. We demonstrated that RU486 inhibits in a dose-dependent way the expression of both classes of IL-2R, thereby mimicking the effects of the glucocorticoid agonist dexamethasone. The maximal effect on the low affinity binding sites was observed at 10 microM (28 +/- 2% of control, P less than 0.001) and on the high affinity IL-2R at 1 microM (from 2938 +/- 74 to 437 +/- 108 binding sites per cell, P less than 0.001). This inhibition of IL-2R expression occurs at a pretranslational level since RU486 decreased the accumulation of beta-chain IL-2R mRNA transcripts. Our data support the concept that the antiglucocorticoid RU486 at pharmacological concentrations can exert agonistic-immunosuppressive effects.

PIP: The effects of RU-486, which has anti-glucocorticoid properties, on expression of the interleukin-2 receptors (IL-2R) in human lymphocytes were examined in terms of its dose effect on 2 types of binding sites, and its suppression of beta-chain IL-2R messenger RNA production. Human peripheral lymphocytes stimulated with phytohemagglutinin (PHA) were incubated with the synthetic glucocorticoid dexamethasone and with RU-486 at various doses. Synthesis of 2 types of IL-2R was measured by immunofluorescence assay of the alpha chain. RU-486 inhibits in a dose- dependent fashion the expression of both classes of IL-2R, acting like an agonist. Maximal suppression was seen at a concentration of 10 mcM for the low affinity binding site, and at 1 mcM for the high affinity rate. Messenger RNA was determined by extracting RNA, fractioning it by electrophoresis on agarose gel, and hybridizing with cDNA probes inserted with a plasmid. RU-486 significantly lowered the accumulation of beta-chain IL-2R mRNA transcripts. Thus RU-486 at pharmacological concentrations acts like a glucocorticoid agonist with immunosuppressive effects.

Experimental study of the immiscible displacement of shear-thinning fluids in pore networks.

The pore scale mechanisms and network scale transient pattern of the immiscible displacement of a shear-thinning nonwetting oil phase (NWP) by a Newtonian wetting aqueous phase (WP) are investigated. Visualization imbibition experiments are performed on transparent glass-etched pore networks at a constant unfavorable viscosity ratio and varying values of the capillary number (Ca), and equilibrium contact angle (theta(e)). Dispersions of ozokerite in paraffin oil are used as the shear-thinning NWP, and aqueous solutions of PEG colored with methylene blue are used as the Newtonian WP. At high Ca values, the tip splitting and lateral spreading of WP viscous fingers are suppressed; at intermediate Ca values, the primary viscous fingers expand laterally with the growth of smaller capillary fingers; at low Ca values, network spanning clusters of capillary fingers separated by hydraulically conductive noninvaded zones of NWP arise. The spatial distribution of the mobility of shear-thinning NWP over the pore network is very broad. Pore network regions of low NWP mobility are invaded through a precursor advancement/swelling mechanism even at relatively high Ca and theta(e) values; this mechanism leads to irregular interfacial configurations and retention of a substantial amount of NWP along pore walls; it becomes the dominant mechanism in displacements performed at low Ca and theta(e) values. The residual NWP saturation increases and the end WP relative permeability decreases as Ca increases and both become more sensitive to this parameter as the shear-thinning behavior strengthens. The shear-thinning NWP is primarily entrapped in individual pores of the network rather than in clusters of pores bypassed by the WP. At relatively high flow rates, the amplitude of the variations of pressure drop, caused by fluid redistribution in the pore network, increase with shear-thinning strengthening, whereas at low flow rates, the motion of stable and unstable menisci in pores is reflected in strong pressure drop fluctuations.