Blood serum concentrations of gonadotropins and α-subunit in patients with gonadotropinomas in relation to the immunoreactivity of pituitary adenoma.

Introduction: Although active gonadotropin-secreting pituitary adenomas are considered very rare, the vast majority of pituitary tumours diagnosed as "non-functioning" express gonadotropins or their free β or α subunits. However, systemic investigations comparing the serum concentrations of follitropin (FSH), lutropin (LH), and α-subunit (αSU) before surgery with the immunoreactivity of the respective substances in the excised tumours are still lacking.

Material And Methods: Immunostaining of FSH, LH, and αSU was compared in 43 surgically removed gonadotropin - expressing pitu-itary adenomas with serum concentrations of the above-mentioned substances before surgery in the same patients.

"Silent" thyrotropin (TSH) expression in acromegaly and clinically non-functioning pituitary adenomas.

Introduction: The pituitary adenomas secreting thyrotropin (TSH) are considered the rarest type of hormonally active pituitary tumour. In spite of that, many cases are described in the literature. On the other hand, the observations of the co-expression of TSH with other pituitary hormones (mostly with growth hormone [GH]) and "silent" expression of TSH in clinically non-functioning pituitary adenomas (CNFPA) are rather scarce.

An evaluation of the effects of somatostatin analogue therapy in non-functioning pituitary adenomas in comparison to acromegaly.

Introduction: Non-functioning pituitary adenomas (NFPA) are often diagnosed late as invasive macroadenomas. The surgical resection is usually incomplete and about 50% of patients require additional surgery. Recent data suggest that somatostatin analogues (SSA), so important in the pharmacotherapy of acromegaly, can also be effective in the management of NFPA.

Expression of follicle stimulating hormone receptors in pituitary adenomas - a marker of tumour aggressiveness?

Introduction: In our earlier study, we found that pituitary adenomas, like other human tumours, express ectopically follicle stimulating hormone receptors (FSHR) in intratumoural blood vessels endothelia and/or tumoural cells. The aim of the present paper was to provide more detailed data on FSHR expression in different subtypes of pituitary adenomas and to evaluate its possible role as a prognostic and/ or predictive biomarker in these tumours.

Material And Methods: Forty two pituitary adenomas, surgically removed, were immunostained with antibodies against the pituitary hormones, antigen Ki-67 and 1-190 fragment of FSHR.

Overexpression of prothymosin alpha is related to pituitary adenoma recurrence but not to adenoma invasiveness and proliferation.

Introduction: Prothymosin alpha (ProTα) is a peptide initially considered as a thymic hormone, but further studies have shown its wide distribution in different tissues and organs. It has a prevalent nuclear localisation and is thought to be involved in the control of proliferation and apoptosis. In earlier studies, the overexpression of ProTα was found in several human tumours, including pituitary adenomas.

Preoperative long-acting octreotide treatment for invasive thyrotropin-secreting pituitary macroadenoma after previous radioiodine thyroid ablation.

We report a 33-year-old woman with invasive thyrotropin-secreting pituitary adenoma after previous thyroid ablation with radioiodine who was successfully treated with transsphenoidal surgery after pre-treatment with octreotide-LAR for 10 months. Since invasive and aggressive thyrotropin-secreting macroadenomas are more frequently observed in patients who have undergone thyroid ablation, we suggest preoperative treatment with somatostatin analogs should be considered in these patients to reduce serum thyrotropin and stabilize or reduce tumor size.

The involvement of angiotensin type 1 and type 2 receptors in estrogen-induced cell proliferation and vascular endothelial growth factor expression in the rat anterior pituitary.

The aim of our study was to examine the involvement of renin-angiotensin system (RAS) in estrogen-induced lactotropes proliferation and vascular endothelial growth factor (VEGF) expression in rat pituitary. The study was performed on Fisher 344 rats underwent 8-day treatment with diethylstilboestrol (DES). The proliferation index (PCNA) and VEGF expression in pituitary sections were estimated using immunohistochemical methods.

Angiotensins inhibit cell growth in GH3 lactosomatotroph pituitary tumor cell culture: a possible involvement of the p44/42 and p38 MAPK pathways.

The local renin-angiotensin system is present in the pituitary. We investigated the effects of angiotensins on GH3 lactosomatotroph cells proliferation in vitro and the involvement of p44/42 and p38 MAPK inhibitors in the growth-regulatory effects of angiotensins. Materials and Methods.

The effects of angiotensin peptides and angiotensin receptor antagonists on the cell growth and angiogenic activity of GH3 lactosomatotroph cells in vitro.

The local renin-angiotensin system (RAS) is present in the pituitary gland, and inhibitory effects of angiotensins on the lactosomatotroph (GH3) cell growth have been revealed. The aim of this study was to examine the influence of various angiotensin peptides and angiotensin AT1, AT2, and AT4 receptors antagonists on the cell proliferation, viability, and VEGF secretion in pituitary lactosomatotroph GH3 cell culture in order to identify receptors involved in antiproliferative effects of angiotensins on GH3 tumor cells. Cell viability and proliferation using Mosmann method and BrdU incorporation during DNA synthesis, and VEGF secretion using ELISA assay were estimated.

Expression of somatostatin receptor subtypes in primary and recurrent gonadotropinomas: are somatostatin receptors involved in pituitary adenoma recurrence?

Objective: Surgical treatment of pituitary macroadenomas often fails because of tumor recurrence after the operation. The causes of tumor recurrence are complex, but one of them may be the high growth potential of the adenoma. As somatostatin receptors mediate antiproliferative, anti-angiogenic and pro-apoptotic actions, it seemed reasonable to investigate their expression in dependence on the adenoma recurrence.

SSTR1 and SSTR5 subtypes are the dominant forms of somatostatin receptor in neuroendocrine tumors.

The effectiveness of the long acting somatostatin analogues like octreotide and lanreotide depends on the expression of specific somatostatin receptors on the target cells. The immunohistochemical method performed on surgically removed tumors searches the expression of receptors at the level of receptor protein and gives us insight into receptor's cellular localization. The aim of study was to assess the presence of all the 5 subtypes of SSTR 1-5 (including 2A and 2B SSTR isoforms) in surgically treated human neuroendocrine tumors (NETs) to establish which receptor subtype is the dominant form of somatostatin receptor in particular tumor and thus to be able to predict which somatostatin analog will be effective in NETs treatment.

Does the response of GH-secreting pituitary adenomas to octreotide depend on the cellular localization of the somatostatin receptor subtypes SSTR2 and SSTR5?

Introduction: The immunohistochemical examination of somatostatin receptor (SSTR) subtypes expression in different endocrine tumours, including pituitary adenomas, revealed membranous or cytoplasmic distribution of SSTR1-5. Currently used long-acting somatostatin analogue octreotide prefers SSTR2 and SSTR5 subtypes. In an earlier study a positive correlation between the summarized score of SSTR2A + SSTR2B expressions and growth hormone (GH) response to octreotide administration was found, independently of receptor distribution within the cell.

Plurihormonality of pituitary adenomas in light of immunohistochemical studies.

Introduction: Plurihormonality of pituitary adenomas can be defined as the ability of an adenoma to express more than one pituitary hormone. The application of immunohistochemistry to diagnose surgically removed pituitary tumours revealed that a great number of pituitary adenomas are in fact plurihormonal. However, data on the incidence and the clinical relevance of the pituitary adenoma plurihormonality are still scarce and controversial.

Expression of somatostatin receptor subtypes in human pituitary adenomas -- immunohistochemical studies.

Background: The highly variable expression of SSTR subtypes in pituitary adenomas (PA) may partially explain why the subgroup of somatotropinomas or other adenomas do not respond to the therapeutic action of currently used long-acting somatostatin analogues like octreotide or lanreotide.

Material And Methods: Our study summarizes the data on expression of all somatostatin receptor subtypes (SSTR 1-5), extended for 2A and 2B SSTR isoforms, revealed by means of immunohistochemistry in dependence to different hormonal phenotype of the tumour.

Results: The pattern of SSTR immunostaining (estimated according to the percentage frequency of appearance) was in acromegaly: SSTR 5 > SSTR 1 > SSTR 2A = SSTR 3 > SSTR 2B, in prolactinomas: SSTR 2B = SSTR 3 = SSTR 5 > SSTR 1 = SSTR 2A, in gonadotropinomas: SSTR 3 > SSTR 2B > SSTR 1 = SSTR 2A > SSTR 5, in corticotropinomas: SSTR 2A > SSTR 1 = SSTR 3 > SSTR 5 > SSTR 2B.

Effects of rosiglitazone--peroxisome proliferators-activated receptor gamma (PPARgamma) agonist on cell viability of human pituitary adenomas in vitro.

Objectives: Rosiglitazone (RGZ) belongs to thiazolidinediones - new class of antidiabetic drugs which are PPARgamma agonists. It was shown that tumoral tissue, including the pituitary adenomas, posses PPARgamma receptors. The activation of PPARgamma receptors inhibits tumour growth in rodents and induces the oncostatic effect on human cancer cell lines.

Somatostatin receptors in GH-secreting pituitary adenomas--their relationship to the response to octreotide.

Twenty pituitary adenomas, surgically removed from patients suffering from acromegaly, were studied. The tumours were immunostained with anti-GH and anti-PRL antibodies and with antibodies raised against particular subtypes of somatostatin receptors (rsst1-5). Expression of rsst immunoreactivity was scored using the following scale: 0--negative reaction, 1--weak reaction, 2--moderate reaction, 3--strong reaction.

"Silent"corticotropinoma.

Objectives: The aim of the study was to evaluate the ACTH-immunopositive pituitary adenomas, especially those without manifestation of Cushing's disease

Material And Methods: 148 pituitary adenomas removed surgically in years 1994--2007 were studied. The paraffin sections were immunostained with antibodies against the pituitary hormones. In 79 adenomas the immunostaining with anti-ACTH antibody was performed Additionally, 23 tumors were also immunostained with anti-Ki-67 (MIB-1) antibody.

Effects of somatostatin on vascular endothelial growth factor (VEGF) secretion from non-functioning pituitary tumoral cells incubated in vitro.

Objectives: The aim of the study was to examine the effect of somatostatin (SST) on vascular endothelial growth factor (VEGF) secretion from clinically non-functioning pituitary tumors incubated in vitro.

Material And Methods: Eight pituitary tumors surgically removed were investigated. All of the tumors were diagnosed before surgery as non-functioning.

Angiotensin peptides regulate angiogenic activity in rat anterior pituitary tumour cell cultures.

Introduction: Angiogenesis has been shown to be necessary for the development and progression of solid tumours. VEGF is one of the crucial pro-angiogenic cytokines produced by the cells of many of the tumours examined, including various types of anterior pituitary adenomas. Angiotensin II (Ang II) is known to regulate the expression of VEGF in a variety of tissues both in the physiological and pathological conditions.

Effects of somatostatin-14 and the receptor-specific somatostatin analogs on chromogranin A and alpha-subunit (alpha-SU) release from "clinically nonfunctioning" pituitary adenoma cells incubated in vitro.

The aim of the study was to examine the effect of somatostatin (SST) and its analogs on the release of chromogranin A (CgA) and alpha-subunit (alpha-SU) from clinically non-functioning pituitary adenomas incubated in vitro. Seven pituitary macroadenomas surgically removed were investigated. All of the tumors were diagnosed before surgery as non-functioning, but they expressed either gonadotropins or their subunits as detected by immunohistochemistry.

Positron emission tomography (18FDG-PET) in the detection of medullary thyroid carcinoma metastases.

Introduction: Medullary thyroid carcinoma (MTC) is usually more advanced at presentation than differentiated thyroid cancers and often has distant metastases. The primary treatment of MTC is total thyroidectomy and regional lymph node dissection. The efficacy of these procedures has been limited by the aggressiveness of the disease and metastatic spread at the time of surgery.

[Pituitary resistance to thyroid hormone--a case report].

Pituitary resistance to thyroid hormone is a very rare cause of hyperthyroidism. It is characterized by normal, or elevated TSH concentration with high concentration of T3 and T4. Here, we present a case of a 24-year-old woman who suffered from mild thyrotoxicosis and diffuse goiter for several years.

Growth-inhibitory action of melatonin and thiazolidinedione derivative CGP 52608 on murine 16/C breast cancer cells.

Objectives: Melatonin may influence directly tumor cells through the specific binding sites. The best known melatonin binding sites are membrane receptors. Recently, the participation of nuclear signalling via estrogen as well as RZR/ROR receptors in oncostatic action of melatonin on the breast cancer has been widely discussed.

Proliferating cell nuclear antigen (PCNA) expression in pituitary adenomas: relationship to the endocrine phenotype of adenoma.

The expression of proliferating cell nuclear antigen (PCNA) correlates to cell proliferation and for this reason it is commonly considered as one of proliferation markers. Since proliferation rate is an important factor determining the tumor aggressiveness, the evaluation of PCNA index (the percentage of PCNA-immunopositive nuclei in the investigated tumor sample) is suggested as useful in predicting pituitary adenoma outcome. Seventy three unselected, surgically removed pituitary adenomas were immunostained with antibodies against the pituitary hormones or their subunits and against the proliferating cell nuclear antigen (PCNA).