Katarzyna Winczyk

Possible Involvement of the Nuclear RZR/ROR-Alpha Receptor in the Antitumor Action of Melatonin on Murine Colon 38 Cancer

Experimental evidence has shown that melatonin (MLT) may act through both membrane and nuclear receptors. Moreover, it was proposed that the nuclear MLT receptor is identical with nuclear orphan receptors called RZR/ROR. Our earlier results suggest that the antitumor action of MLT depends mainly on nuclear signaling. In the present study, we investigated whether CGP 55644 (an antagonist of the nuclear RZR/RORα receptor) changes the oncostatic effects of MLT on murine Colon 38 cancer. The experiment was performed on adult male B6D2F1 mice. MLT or CGP were given either alone or combined during 10 days, and cell proliferation, apoptosis and the proliferation/apoptosis (P/A) ratio were determined. Cell proliferation was assessed by incorporation of bromodeoxyuridine into tumor cell nuclei (labeling index – LI). The number of apoptotic cells using the TUNEL method was considered as an index of apoptosis. It was found that MLT inhibited cell proliferation. Addition of CGP to MLT diminished the antiproliferative effect of MLT. Moreover, MLT increased the apoptotic index, but CGP decreased apoptosis. In addition, CGP given together with MLT blocked its proapoptotic effect. Given alone, MLT strongly lowered the P/A ratio, and addition of CGP to MLT abolished the effect of MLT on the P/A ratio. Based on our data, we conclude that nuclear RZR/RORα receptors participate in the oncostatic action of MLT.

Time of Day-Dependent Effects of Thyroliberin and Thyrotropin on Thymocyte Proliferation in Rats

Our earlier studies have shown that thyroliberin (TRH) as well as thyrotropin (TSH) enhanced thymus cell proliferation. The aim of the present study was to investigate whether the effects of TRH and TSH on thymocyte proliferation depend on time of day. A single subcutaneous injection of TRH (25 μg/animal) or TSH (3 IU/animal) was made at 9:00 h (1 h after light onset) or at 18:00 h (10 h after light onset) in 3-month-old male Wistar rats. The animals were killed 24 h later. The proliferation of thymocytes was assessed by incorporation of bromodeoxyuridine into cell nuclei. Thymocyte proliferation was significantly increased by TSH administration at 9:00 h, whereas treatment given at 18:00 h was ineffective. TRH enhanced the proliferation when injected at 9:00 h, but had an inhibitory effect when administered at 18:00 h. These data indicate that the effects of TRH and TSH on thymocyte proliferation are dependent on time of day.

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.

Immunohistochemical detection of angiotensin receptors AT1 and AT2 in adrenal tumors.

Angiotensin II is well known to affect the adrenal cell growth and function. Angiotensin receptors AT1 and AT2 were found to be present in the normal adrenal gland. However, the data on the expression of the angiotensin receptors in the adrenal tumors are very scarce. To overcome this gap, the paraffin sections of the adrenal cortical tumors and of pheochromocytomas from the archival material were immunostained with antibodies raised against AT1 (sc-1173) and AT2 (sc-9040) receptor proteins. In hyperplasia of the adrenal cortex and in benign adrenocortical adenomas, both functioning and non-functioning, the AT1 immunostaining was present mainly in the cell membranes. A positive immunoreaction was also found in the subpopulation of cell nuclei and within the cytoplasm. In the adrenal cancer, as well as in pheochromocytomas, neither cell membranes nor cell nuclei were immunostained with anti-AT1 antibody. However, a weak AT1 immunostaining was present within the cytoplasm of tumoral cells. With anti-AT2 antibody, in all tumors investigated, the tumoral cells were immunonegative but moderate to strong AT2 immunostaining was observed in the walls of intratumoral blood vessels and in the interstitial tissue. Our data indicates that the expression of AT1 receptors is altered in adrenal cancer and in pheochromocytomas. The expression of AT2 receptors, in turn, may be connected with the process of tumoral neo-angiogenesis.

Effects of Somatostatin and Its Analogues on Tyrosine Kinase Activity in Rodent Tumors

The effects of native somatostatin-14 (SS-14) and of its two analogues, octreotide and CH-275, on the activity of tyrosine kinases (TK) in two rodent tumors (rat pituitary tumor and murine colonic cancer) were studied in vitro. The activity of TK was measured in tissue homogenates using γ[32P]ATP as the donor of the phosphoryl group and poly(Glu80, Tyr20) as a substrate. It was found that native SS-14 inhibited TK activity in both investigated tumors. Octreotide, which acts preferentially via somatostatin receptor subtype 2 (SSTR2), was very effective in inhibiting TK activity in the rat pituitary tumor, but it is a rather weak inhibitor of TK activity in murine colonic cancer. CH-275, a selective ligand of the SSTR1 subtype of SS receptors, suppressed TK activity in the pituitary tumor but was ineffective in the colonic cancer. It is hypothesized that the effect of neuropeptide somatostatin (SS-14) on murine colonic cancer is exerted via the subtype of receptor which does not interact with CH-275 and has no or low affinity for octreotide (SSTR 4, 3 or 5?).

Immunohistochemical detection of follicle stimulating hormone receptor (FSHR) in neuroendocrine tumours

INTRODUCTION Follicle stimulating hormone receptors (FSHR) are well known to be expressed in gonads and in gonadal tumours. Recently,their incidence has also been revealed in endocrine non-gonadal tumours such as adrenal and pituitary tumours. Moreover, FSHR immunostaininghas also been reported in endothelium of intra- and peritumoral blood vessels of a large series of cancers. The presentpaper reports on the incidence of FSHR in both tumoral cells and some intratumoral blood vessels of neuroendocrine tumours (NETs). MATERIAL AND METHODS Sixteen NETs samples were taken from 14 patients. The tumour samples were immunostained using the antibodyraised against 1-190 amino acid sequence from the human FSH-R and anti-Ki67 antibody. RESULTS In all the samples examined, the majority of tumoral cells were immunostained with anti-FSHR antibody. Positive immunostainingconcerned also the intratumoral blood vessels endothelia in a half of the examined samples. Immunopositive blood vessels were foundmore often in tumours with higher Ki-67 index. CONCLUSION FSHR expressed in NETs, if they are functional, may mediate the signals which can enhance further tumour growth.

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.

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. The present study deals with the relations of ProTα to the pituitary adenoma hormonal phenotype, proliferation, recurrence and invasiveness. MATERIAL AND METHODS Sixty two pituitary adenomas were included in the study. The invasiveness of the tumours was estimated before surgery by means of magnetic resonance imaging. The paraffin sections of the tumours were immunostained with an antibody against the C-terminal fragment (101-109) of ProTα and with anti-Ki-67 antibody. The hormonal phenotype of the investigated pituitary adenomas had been established previously by means of immunostaining with antibodies to pituitary hormones (GH, PRL, FSH, LH, TSH, ACTH and α-subunit). RESULTS Strong immunostaining with anti-ProTα antibody occurred in the subpopulation of cell nuclei and the walls of intratumoural blood vessels. ProTα index is higher in clinically non-functioning pituitary adenomas (CNFPA) compared to any type of functioning adenomas. There was no difference in the percentage of ProTα- positive cell nuclei in non-invasive vs. invasive adenomas, but it was significantly more frequent in recurrent than in primary tumours. Moreover, the decrease of ProTα index was found in somatotroph tumours treated with somatostatin analogues vs. untreated ones. The percentage of ProTα nuclei did not correlate with Ki-67 index. CONCLUSIONS The overexpression of nuclear ProTα in pituitary adenomas is related to tumour recurrence, but not to proliferation or invasiveness.

Immunohistochemical detection of prothymosin alpha in pituitary adenomas - a new marker of tumor recurrence?

Forty pituitary adenomas were immunostained with an antibody raised against the C-terminal fragment (101-109) of human prothymosin alpha (PT alpha). The strong positive immunostaining was found in the subpopulation of cell nuclei and intratumoral vessel walls, while the cytoplasm of adenoma cells was slightly immunopositive. The significantly higher percentage of PT alpha-positive cell nuclei was found in recurrent pituitary adenomas as compared with primary tumors. However, there was no correlation between the percentage of PT alpha-positive cell nuclei and Ki-67 indices. Gonadotropinomas were characterized by higher nuclear PT alpha expression in comparison to other pituitary adenomas, which is probably linked with the high recurrence rate of these tumors. It is suggested that PT alpha immunostaining may be helpful in predicting the pituitary tumor recurrence. However, this conclusion needs to be confirmed in further prospective studies. Moreover, PT alpha may be also useful as an immunohistochemical marker of the intratumoral microvasculature.