Hanna Pisarek

Expression of somatostatin receptor subtypes in human thyroid tumors: the immunohistochemical and molecular biology (RT-PCR) investigation

Human endocrine tumors often express the somatostatin receptors SSTR 1–5 with different intensity. It has been widely investigated their distribution in pituitary adenomas, brain tumors, adrenal tumors and neuroendocrine tumors in gastrointestinal tract (NET). Some of studies also concern the expression of SSTRs in thyroid tumors but they are mainly limited to parafollicular C cells – derived medullary thyroid carcinomas (MTC). Results of SSTR 1–5 detection in other thyroid pathologies like follicular adenomas and papillary cancers are still scarce and often controversial, depending of investigation method used. The aim of this study was to report the presence of all the 5 subtypes of SSTR (including 2A and 2B SSTR isoforms) in some surgically treated human thyroid tumors by means of immunohistochemistry and real-time PCR method and to correlate the results obtained with both techniques. SSTR 1 protein was expressed in 88.8% of investigated cases, SSTR 2A and 2B both in 44.4%, SSTR 3 in 55.5%, SSTR 4 in 11.2% and SSTR 5 in 33.3%. SSTR 1 is the dominant form in the thyroid gland tumor and hyperplasia. We found positive confirmation of both methods in 88.8% for SSTR 1, 2A, 3 subtypes, in 22.2% for SSTR 4 and in 100% for SSTR 5. It suggests that somatostatin multiligand analogs or selective SSTR 1 agonists may be used in thyroid tumors treatment.

Immunocytochemical Investigations on the Vascularization of Pituitary Adenomas.

Blood vessels within pituitary adenomas were visualized using the immunocytochemical reaction for Factor VIII (von Willebrand Factor), a specific marker of the vascular endothelium. The number of immunopositive vascular profiles were counted and expressed as a mean number per one microscopic field. The results were related to the type of adenoma, established on the basis of immunocytochemical investigation using the antibodies against pituitary hormones or α-subunit (α-SU). It was found that the richest vascularization occurred in adenomas expressing follicle-stimulating hormone (FSH). The possible role of FSH in pituitary angiogenesis is discussed.

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 receptors 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. 18 samples of neuroendocrine tumors (surgically excised tumors or biopsies) were immunostained with specific antibodies. Expression of SSTR was scored semiquantitatively. Only strong or moderate immunostaining was considered as positive reaction. The summarized expression pattern of SSTR in the investigated neuroendocrine tumors in our material was: SSTR 1> SSTR 5> SSTR 3> SSTR 2A> SSTR 2B. The receptors were distributed mainly in the area of cells cytoplasm with a few specimens showing only membranous or mixed: membranous--cytoplasmic localization. The observed pattern suggests that apart from octreotide and lanreotide, newly synthesized multiligand analogs such as SOM 230, KE 108 or SSTR 1 and SSTR 5 selective analogs could be effective in NETs treatment.

Somatostatin receptors in human adrenal gland tumors--immunohistochemical study.

Somatostatin receptors subtypes (SSTR 1-5) were demonstrated in surgically obtained adrenal gland tumors by means of immunohistochemistry (IHC). Results of the present study demonstrate that somatostatin receptors are expressed in adrenal tumors in a varied manner which is specific in each case. It provides different diagnostic and therapeutic possibilities.

Immunohistochemical detection of FSH receptors in pituitary adenomas and adrenal tumors

Objectives . Follicle stimulating hormone (FSH) receptors (FSHR) are physiologically expressed in the ovary and testis. It is well known that FSHR are also expressed in gonadal cancers, but the data on their incidence in extra-gonadal tumors are scarce. Recently, the expression of FSHR in the vascular endothelium within different human cancers was found, but nothing is known on FSHR appearance in non-gonadal endocrine tumors. The present paper reports on the immunohistochemical detection of FSHR in human pituitary adenomas and adrenal tumors. Materials and methods . The study included samples of 28 pituitary adenomas and 36 adrenal tumors. Moreover, 2 samples of non-tumoral adrenal glands were also studied. FSH receptor immunostaining was performed on paraffin sections using the rabbit anti-human FSH-R polyclonal antibody raised against 1-190 amino acid sequence from the human FSH-R (sc-13935). The pituitary adenomas were immunostained to reveal the pituitary hormones and the proliferation marker Ki-67. Results . In the pituitary adenomas, positive immunostaining with anti-FSHR antibody occurred in the adenoma cells cytoplasm and endothelia of the intra- and peritumoral blood vessels. The cytoplasmic immunostaining was found in the majority of investigated tumors but the intensity of staining was weak to moderate. There is some tendency towards the higher cytoplasmic FSHR score in tumors with higher Ki-67 index (atypical adenomas). In contrast to the cytoplasm, the FSHR immunostaining in blood vessels is strong and concerns all the investigated samples. Strong FSHR immunostaining is present in the endothelium of intra- and/or peritumoral blood vessels in the majority of pheochromocytomas, approximatively one half of the adrenocortical adenomas and both cases of the adrenal cancers. The immunostaining is detectable also in the tumoral cell cytoplasm in all but one examined pheochromocytomas.. All the investigated adrenocortical adenomas presented strong immunostaining of cell membranes. No immunostained cell membranes were found. in adrenal cancers. The positive immunostaining was found in glandular cells, but not in blood vessels, of non-tumoral adrenal cortex and medulla. Conclusions . Immunostaining of FSHR often occurs in the endothelium of intra- and/or peritumoral blood vessels of pituitary adenomas and benign and malignant adrenal tumors. The immunostaining may be also present in tumoral cells. A role of FSHR expression in these tumors (stimulation of angiogenesis? stimulation of cell growth?) needs further studies to be clarified.

Differential expression of somatostatin receptor subtype-related genes and proteins in non-functioning and functioning adrenal cortex adenomas.

Adrenocortical adenomas display highly variable expressions of somatostatin receptor (SSTR) subtypes, whose expression is mandatory (although not always sufficient) to achieve the positive effects of somatostatin (SST) analog therapy. Immunohistochemistry (IHC) is the main method used to investigate receptor protein expression. The molecular biology method - polymerase chain reaction (PCR) - is also often used to investigate receptor expression. Nevertheless, the expression of receptor mRNA and the respective receptor protein is not always synchronized. The aim of this study was to investigate SSTR expression by IHC in adrenal adenomas, to compare the results to data obtained by real-time PCR and to determine whether hormonally functioning and non-functioning adenomas differ in this respect. Adrenocortical adenomas were removed surgically from 13 females and 2 males. The tissues were obtained from 9 non-functioning and 6 functioning adenomas. The intensity of IHC reaction was scored semiquantitatively by two independent observers. Real-time PCR was performed using pairs of primers in a reaction amplified along a gradient of temperatures. Amplified DNA was measured by monitoring SYBR-Green fluorescence. In non-functioning tumors, compatibility between IHC and PCR results was observed for SSTR 1 and 2 in 62.5% of the samples. Fifty percent of patients demonstrated compatibility for SSTR 4 and 5 and 37.5% for SSTR 3. In hormonally active adenomas, total compatibility of both methods was noted for SSTR 2 (100%). The compatibility obtained for SSTR 5 was 66.6%. We conclude that receptor gene and respective receptor protein expression are not always synchronized. Messenger RNA detection alone is not sufficient to predict the presence of the receptor protein acting as a target for SST and its analogs.

Ectopic expression of follicle-stimulating hormone receptors in thyroid tumors

Introduction In normal conditions follicle-stimulating hormone receptors (FSHR) are expressed in the ovary and the testis. They can also be expressed in gonadal tumors. However, recently we have found FSHR immunostaining in pituitary adenomas, adrenal tumors and neuroendocrine tumors (carcinoids). The aim of this study was to determine whether the same occurs in thyroid tumors. Material and methods Thirty-six samples of surgically excised thyroids were examined. Follicle-stimulating hormone receptors immunostaining was performed on paraffin sections using the rabbit anti-human FSHR polyclonal antibody raised against a 1-190 amino acid sequence from the human FSHR (sc-13935, Santa Cruz). Results Normal thyroid follicles do not show immunopositivity for FSHR. The same concerns the majority of benign lesions, diagnosed as hyperplasia nodularis or thyroid adenomas. However, positive FSHR immunostaining in some follicles was observed. In all but one thyroid cancer (15 papillary, 10 follicular cancers and one case of anaplastic thyroid cancer) 10–100% of tumor cells exhibit positive FSHR immunostaining. In about 40% of samples FSHR immunoreactivity can be observed also in the endothelia of intrathyroidal blood vessels. This immunopositivity was more frequent in the samples of thyroid cancers (13/27) than in benign lesions (2/9). Conclusions Ectopic positive FSHR immunostaining is also present in thyroid cancers, and, to a lesser degree, in benign lesions but not in the normal thyroid epithelium.

Expression of follicle stimulating hormone receptors (FSHR) in thyroid tumours - a marker of malignancy?

BackgroundIn normal conditions FSHR are expressed in granulosa cells of the ovary and Sertoli cells of the testis. They can be expressed also in gonadal tumours. However, recently the expression of FSHR was found in tumoral cells and intra-tumoral blood vessels of many other tumours, including thyroid tumours. Aim of this study was to see whether the expression of FSHR can be useful in the differentiation of benign and malignant thyroid lesions.Methods44 samples of surgically excised thyroids were immunostained with anti- FSHR antibody raised against 1–190 amino acid sequence from the human FSHR.ResultsNon-neoplastic thyroid follicles (i.e. the follicles situated outside the tumour) do not show the immunostaining for FSHR. The same concerns the majority of follicular adenomas. In contrast, 87.5% of follicular cancers, the same percentage of papillary cancers and all the examined undifferentiated cancers showed the FSHR immunopositivity of tumoral cells. A tendency towards the higher frequency of FSHR – positive blood vessels also concerns malignant thyroid tumours.ConclusionsThe ectopic FSHR immunostaining seems to be useful to differentiate malignant from benign lesions, especially follicular cancers from follicular adenomas. However, the further studies on larger material are needed.

Ultrafiltration – an alternative method to polyethylene glycol precipitation for macroprolactin detection

Introduction The aim of the study was to evaluate two methods of macroprolactin (MaPRL) detection – precipitation with polyethylene glycol (PEG) and ultrafiltration and to compare these techniques with “gold standard” – gel filtration chromatography (GFC). Material and methods The study was conducted on 245 patients – 45 with organic and 200 with functional hyperprolactinaemia. In all the subjects MaPRL was detected by precipitation with PEG and ultrafiltration. Additionally, gel filtration chromatography was performed in some of the serum samples. Results Macroprolactinaemia was detected in 27 patients – 8 with prolactinoma and 19 with functional hyperprolactinaemia. Assessing positive and negative results for MaPRL, we observed high diagnostic agreement (95.9%) and positive correlation (r = 0.506, p < 0.001) between the methods. The results of precipitation and ultrafiltration positive for MaPRL were concordant in 63%. The dominance of MaPRL detected with precipitation and/or ultrafiltration was confirmed by GFC in 76% of cases (all patients with functional hyperprolactinaemia). Among 6 examined patients with prolactinoma, GFC showed four false-positive results – 1 case of precipitation and 3 cases of ultrafiltration. Conclusions Efficacy of MaPRL detection with precipitation and ultrafiltration is comparable especially in cases of functional hyperprolactinaemia. In patients with prolactinoma, precipitation seems to be a more efficient separation method.

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. MATERIAL AND METHODS We analysed data of patients who had been treated up to 10 years previously with SSA: 40 with acromegaly (23 - primary, 17 - recurrent tumours) and 22 with NFPA (4 - primary, 18 - recurrent tumours). Hormonal profile, dynamics of tumour size change, ophthalmic syndromes, somatostatin receptor (SSTR) scintigraphy, and immunohistochemistry of SSTR subtypes of operated tumours as well as side effects were investigated. RESULTS Biochemical cure of acromegaly was achieved in 57.5% of patients, while reduction of tumour size was observed in 37% of patients and it was more frequent in not-operated cases. Regarding NFPA, stabilisation of tumour size was noticed in 68% of patients. Tumour shrinkage was reported in 9% of cases, but in 23% of the study group the adenoma size increased with indication for reoperation. CONCLUSIONS The efficacy of SSA in NFPA is much lower in comparison to their well-established effects in the treatment of acromegaly. Stabilisation of tumour size, which is observed in the majority of NFPA, is significantly more frequent in comparison to the natural history of untreated NFPA and our previous studies as well. Analysis of SSTR subtypes is an argument in favour of introduction of novel broad-spectrum SSA that may be more effective in the treatment of NFPA. Referring to acromegaly, adenoma size decrease was reported more frequently in primary therapy. Considering recurrent tumours better outcomes were achieved in patients who were pre-treated with SSA before planned surgery. (Endokrynol Pol 2016; 67 (3): 292-298).