Preceding studies have indicated that aberrant expression levels rather than genetic changes of GADD45γ, MEG3, and p8 gene might play a role in the pathogenesis of pituitary adenomas. We analysed their expression in various normal human tissues and in different pituitary tumour types, and investigated GADD45γ mutations in a subset of adenomas. Absolute quantification by real-time RT-PCR was performed in 24 normal tissues as well as in 34 nonfunctioning, 24 somatotroph, 12 corticotroph adenomas, 4 prolactinomas, 1 FSHoma, and in 6 normal pituitaries. Furthermore, we investigated the relationship between clinical data and gene expression. A subset was screened for GADD45γ mutations by single strand conformation polymorphism analysis (SSCP) and sequencing. All normal human tissues expressed GADD45γ, MEG3, and p8 mRNA. For GADD45γ, significantly lower expression levels were found in nonfunctioning adenomas compared with normal pituitary and somatotroph adenomas. P8 and MEG3 mRNA levels were significantly lower in nonfunctioning and corticotroph adenomas compared with normal pituitary. Expression of GADD45γ was significantly higher in pituitary adenomas of female patients. No mutation was found in the GADD45γ gene. GADD45γ, MEG3, and p8 appear to have physiological functions in a variety of human tissues. GADD45γ, MEG3, and P8 may be involved in the pathogenesis of nonfunctioning and corticotroph pituitary tumours. Female gender seems to predispose to slightly higher GADD45γ expression in pituitary adenomas. Mutations of the GADD45γ are unlikely to be involved in the pathogenesis of pituitary adenomas.

5 Human somatostatin receptor subtypes (sst1-5) mediate the antisecretory and antiproliferative effects of somatostatin. We examined somatostatin receptor protein expression in 28 human normal tissues. Immunostaining was performed with specific polyclonal antibodies for sst1-5. Staining pattern and distribution of ssts were evaluated. Anterior pituitary was positively stained for all 5 ssts. Pancreatic islets exhibited a positive staining for sst1-3 and sst5. Adrenal cortex expressed all 5 receptor subtypes, while the medulla was positive for sst3 and sst5 only. The thyroid expressed sst5 only, limited to single interfollicular cells. All 5 ssts were detected in the ovary, limited to luteinized granulosa cells of the corpus luteum. In the testis, sst2A was detected in the basal parts of the tubules, while sst5 was positively stained in the luminal parts. Sst1 was found in Leydig cells only. Stomach was positively stained for all 5 ssts. Investigation of the kidney revealed differential expression, with sst2A being found in the glomerules. The tubules expressed all 5 ssts. In the bone marrow cells of the granulocytopoiesis expressed sst2A only. The cerebellum expressed sst5 in a certain cell type, representing presumably Purkinje cells, while sst2A was stained in intercellular fibers. The expression of somatostatin receptor subtypes in a variety of human normal tissues may indicate a physiological role in these organs. Somatostatin analogues may offer new diagnostic and therapeutic implications for tumours related to these tissues. However, treatment of defined tumours with somatostatin analogues may also alter other normal tissues.

In the absence of preoperative somatostatin receptor ( SST) scans, knowledge of immunohistochemical SST2 tumor expression may help predicting the success of somatostatin analogue-based follow-up studies and treatment of neuroendocrine tumors (NET). We studied the association between SST immunostaining and tracer uptake in [(111)In]-DTPA octreotide (DTPAOC) scintigraphy and [(68)Ga]-DOTA-D-Phe(1)-Tyr(3)-octreotide (DOTATOC) positron emission tomography (PET)/computed tomography (CT). Retrospective analy-sis of 36 NET patients was carried out. In 40 tumors, immunohistochemical SST2, SST3, and SST5 expressions were analyzed using a pathological scoring, applying monoclonal ( SST2) or polyclonal antibodies (SST3, SST5). In 14 lesions, [(111)In]-DTPAOC uptake was assessed by a semiquantitative score. In 26 tumors, [(68)Ga]-DOTATOC PET/CT was quantified using an uptake score and maximal standard uptake value (SUV(max)). Combined and separate qualitative analysis of SST scans revealed significant associations between increased tracer uptake and immunohistochemical SST2 detection (combined: rho=0.56, p=0.0002, [(111)In]-DTPAOC: rho=0.63, p=0.0152, and [(68)Ga]-DOTATOC: rho=0.52, p=0.0065, respectively). In contrast, SST3 and SST5 immunostaining was not associated with tracer uptake (all p>0.14). The semiquantitative immunohistochemical score for SST2 was associated with the [(68)Ga]-DOTATOC uptake score and SUV (max) values (rho=0.67, p=0.0002 and rho=0.63, p=0.0010, respectively), but not with the [(111)In]-DTPAOC uptake score (rho=0.24, p=0.4). In patients without preoperative SST scans, knowledge of immunohistochemical SST2 expression may help estimating the value of SST imaging in the clinical follow-up, in particular in those lesions with positive SST2 immunostaining. Negativity for SST2, however, does not rule out tracer uptake in some patients, with heterogeneous SST2 expression within the tumor as a potential explanation.

Ghrelin is a peptide thought to be involved in the regulation of appetite. Furthermore, significant effects on the release of growth hormone (GH) and ACTH were demonstrated. Contributing to the physiological relevance of this hormone, we investigated the expression of ghrelin and its receptor (GHS-R) in several normal human tissues. RNA samples (BD Biosciences) underwent one-step TaqMan Real-Time RT-PCR. Immunohistochemistry was performed on paraffin-embedded tissues using specific primary antibodies against ghrelin and its receptor. Relevant ghrelin mRNA levels were detected in all human tissues with the highest levels in stomach, pituitary, and small intestine. By immunohistochemistry, ghrelin peptide expression was detectable in reproductive and endocrine organs (ovary, anterior pituitary, adrenal gland), and organs of the gastrointestinal tract (stomach, pancreas). GHS-R1a mRNA expression was demonstrated in 10 of 24 human organs analyzed with the highest levels in pituitary, adrenal gland, and spinal cord. Expression of the receptor peptide was detected by immunohistochemistry in endocrine and reproductive organs (anterior pituitary, thyroid, pancreas, testis), parts of the CNS (cerebrum, cerebellum), and in single cells of bone marrow. Expression of both ghrelin and its receptor in endocrine and reproductive organs may indicate new endocrine or paracrine mechanisms of regulation in these tissues.

Ghrelin is a newly characterized, widely distributed peptide thought to be involved in the regulation of appetite. Significant effects on the release of growth hormone (GH) and ACTH have been demonstrated. This study compares the expression of ghrelin and its receptor (GHS-R) in various adrenal tumors and normal adrenal gland. Normal adrenal tissue was obtained after autopsy. Tissue was obtained from 13 pheochromocytomas (PHEOs), 15 cortisol-secreting adenomas (CPAs), 12 aldosterone-secreting adenomas (APAs), and 16 nonfunctional adenomas (NFAs) following laparoscopic surgery. Expression of ghrelin and GHS-R1a was investigated on RNA levels by using real-time reverse transcription polymerase chain reaction (RT-PCR) and on protein levels by using immunohistochemistry. In the seven normal adrenal glands analyzed, ghrelin mRNA levels were 12-fold lower than in stomach. Ghrelin protein expression was confirmed by immunohistochemistry. In all adrenal tumors, relevant levels of ghrelin mRNA were observed, with significantly lower expression in PHEOs and APAs than in normal adrenal gland. Ghrelin protein was detected in 0% of PHEOs, 55% of APAs, 87% of CPAs, and 54% of NFAs. GHS-R1a mRNA expression was detectable in normal adrenal gland, but the receptor protein was absent. In adrenal tumors, detectable levels of receptor mRNA were found in 38% of PHEOs, 13% of CPAs, and 25% of NFAs. GHS-R1a protein was absent in the majority of adrenal tumors. Expression of ghrelin in normal adrenal gland and adrenal tumors may indicate some unknown physiological function. The pathophysiological relevance of ghrelin expression in adrenal tumors remains to be investigated.

Background: Somatostatin (SRIF) is a widely distributed peptide with effects on virtually all endocrine/exocrine secretions and cell proliferation in normal and tumor tissues. In a previous study, we demonstrated specific somatostatin receptor subtype (sst1–5) expression profiles in various adrenal tumors using RT-PCR. In this study, we investigated the effects of SRIF, octreotide (Oct) and the new multi-receptor ligand SOM230 (SOM) on sst expression in primary cell cultures of normal adrenal gland and various adrenal tumors.

Aims: Somatostatin (SRIF) is a widely distributed peptide with effects on virtually all endocrine/exocrine secretions and cell proliferation in normal and tumor tissues. In a previous study, we demonstrated specific somatostatin receptor subtype (sst) expression profiles in various adrenal tumors using RT-PCR. Cortisol-producing adenomas (CPA) predominantly expressed sst2, 3 and 5. In aldosterone-producing adenomas (APA), expression of all 5 ssts was distributed equally and ranged from 45–65%. In this study, we investigated the effects of SRIF, octreotide (Oct) and the new multi-receptor ligand SOM230 (SOM) in primary cell cultures of CPA and APA.

Background: Somatostatin (SRIF) is a widely distributed peptide with inhibitory effects on cell proliferation in normal and tumor tissues. In RNA obtained from normal adrenal gland, we demonstrated significant expression of all five ssts using RT/PCR. Pheochromocytomas, Conn adenomas, Cushing's adenomas and nonfunctional adenomas showed specific sst expression profiles for each tumor typ. To understand the regulation of sst expression in the adrenal gland, we investigated the transcriptional activity of the sst 1–5 promoters.

Somatostatin (SRIF) is a widely distributed peptide with growth-inhibiting effects in various tumors. So far, five distinct human SRIF receptor subtypes (sst1-sst5) have been identified. We investigated expression of the five ssts in various adrenal tumors and in normal adrenal gland. Tissue was obtained from ten pheochromocytomas (PHEOs), nine cortisol-secreting adenomas (CPAs), eleven aldosterone secreting adenomas (APAs) and eight non-functional adenomas (NFAs) after retroperitoneoscopic surgery, and used for RNA extraction. Adrenal tissue surrounding the tumor was available for analysis in twenty-seven cases. Receptor expression was studied by RT-PCR using sst-specific primers and subsequently confirmed by Southern blotting. Expression of all five receptor subtypes was observed in RNA obtained from normal adrenal gland. Furthermore, each receptor subtype was expressed in more than 50 % of all tumors analyzed. No sst5 expression was found in PHEOs, while sst1 was present in nearly all of these tumors. Only a few of the CPAs expressed subtypes sst1 and sst4. Expression of all five subtypes was distributed equally in APAs. No sst4 was found in any of the NFAs. Differential expression of ssts in various adrenal tumors may point to new aspects in the pathogenesis of these adenomas. Furthermore, the presence of specific ssts could expand the diagnostic and therapeutic strategies during management. New subtype specific analogues of SRIF may be used in the future depending on the type of adrenal tumor and receptor subtype expressed.

The somatostatin analogues octreotide and lanreotide are frequently used for the treatment of GH-secreting tumors. Whereas these analogues preferentially bind to somatostatin receptor subtype 2 (sst2), the novel somatostatin analogue SOM230 exhibits high affinity to four of the five human ssts (sst1, sst2, sst3, and sst5). SOM230 may therefore offer therapeutic applicability in the treatment of pituitary adenomas expressing these subtypes. We established a quantitative method to analyze expression levels of sst1, sst2, and sst5. Tissue from 40 pituitary adenomas was obtained, including 6 GH-secreting (GH), 9 ACTH-secreting, 1 FSH-secreting, and 24 non-functioning tumors. RNA samples underwent one-step TaqMan™ real-time RT-PCR. Sst mRNA levels were normalized to GAPDH mRNA levels obtained in the same reaction, and standard curves were produced for each subtype using specific cDNA constructs.