Giulia Franchi

Octreotide and the mTOR Inhibitor RAD001 (Everolimus) Block Proliferation and Interact with the Akt-mTOR-p70S6K Pathway in a Neuro-Endocrine Tumour Cell Line

Background/Aim: The mode of action of the somatostatin analog octreotide on neuro-endocrine tumour proliferation is largely unknown. Overexpression of the proto-oncogene Akt/PKB (protein kinase B) has been demonstrated in certain neuro-endocrine tumours: Akt activates downstream proteins including mTOR and p70S6K, which play an important role in cell proliferation. RAD001 (everolimus) is a novel agent that is being trialled in the treatment of neuro-endocrine tumours, and is known to interact with mTOR. We explored the mechanism of action of octreotide, RAD001, and their combination on cell proliferation and kinase activation in a neuro-endocrine tumour cell line (rat insulinoma cell line, INS1). Methods: Proliferation assays were used to determine the effects of octreotide, RAD001, and their combination on cell proliferation. Western blotting was used to characterize the expression of phosphorylated Akt, phosphorylated TSC2, phosphorylated mTOR, and phosphorylated 70S6K. Results: Treatment with octreotide and RAD001 inhibited proliferation and attenuated phosphorylation of all downstream targets of Akt: TSC2, mTOR, and p70S6K. Conclusions: In this cell model, octreotide and RAD001 appear to act through a similar pathway and inhibit the Akt-mTOR-p70S6 kinase pathway downstream of Akt. There may be some overlapping effects of the two inhibitors on the mTOR pathway, although it is likely that other additional effects may differentiate the two agents.

Natural history of gastro-entero-pancreatic and thoracic neuroendocrine tumors. Data from a large prospective and retrospective Italian Epidemiological study: THE NET MANAGEMENT STUDY

Background: The few epidemiological data available in literature on neuroendocrine tumors (NET) are mainly based on Registry databases, missing therefore details on their clinical and natural history. Aim: To investigate epidemiology, clinical presentation, and natural history of NET. Design and setting: A large national retrospective survey was conducted in 13 Italian referral centers. Among 1203 NET, 820 originating in the thorax (T-NET), in the gastro-entero-pancreatic tract (GEP-NET) or metastatic NET of unknown primary origin (U-NET) were enrolled in the study. Results: 93% had a sporadic and 7% a multiple endocrine neoplasia type 1 (MEN1)-associated tumor; 63% were GEP-NET, 33% T-NET, 4% U-NET. Pancreas and lung were the commonest primary sites. Poorly differentiated carcinomas were <10%, all sporadic. The incidence of NET had a linear increase from 1990 to 2007 in all the centers. The mean age at diagnosis was 60.0±16.4 yr, significantly anticipated in MEN1 patients (47.7±16.5 yr). Association with cigarette smoking and other non-NET cancer were more prevalent than in the general Italian population. The first symptoms of the disease were related to tumor burden in 46%, endocrine syndrome in 23%, while the diagnosis was fortuity in 29%. Insulin (37%) and serotonin (35%) were the most common hormonal hyper-secretions. An advanced tumor stage was found in 42%, more frequently in the gut and thymus. No differences in the overall survival was observed between T-NET and GEP-NET and between sporadic and MEN1 -associated tumors at 10 yr from diagnosis, while survival probability was dramatically reduced in U-NET. Conclusions: The data obtained from this study furnish relevant information on epidemiology, natural history, and clinico-pathological features of NET, not available from the few published Register studies.

Cytological Ki-67 in pancreatic endocrine tumours: An opportunity for pre-operative grading

The cytological Ki-67 expression measured on cytological samples collected by endoscopic ultrasonography-guided fine needle aspiration cytology (EUS-FNAC) may provide pre-operative indications for pancreatic endocrine tumours (PETs) management. The aim of our study was to assess reliability of Ki-67 expression measured on cytological samples obtained by EUS-FNAC in patients with PETs. Eighteen patients with PETs underwent EUS-FNAC before surgery. Ki-67 expression was measured on FNACs and on histological sections. Using a cut-off of 2%, percent agreement of Ki-67 expression on cytological and histological samples was 89% (k-statistic: 0.78, 95% confidence intervals (95% CI): 0.5, 1.0). Using cut-off values of 2 and 10%, percent agreement was 78% (k-statistic: 0.65, 95% CI: 0.3, 0.9). Ki-67 expression measured on cytological samples obtained by EUS-FNAC before surgery showed good agreement with that measured on histological samples.

A mutation and expression analysis of the oncogene BRAF in pituitary adenomas

Objective  BRAF is an oncogene that is commonly mutated in both melanomas and papillary thyroid carcinomas, usually at position V600E that leads to constitutive activity in the Ras–mitogen‐activated protein kinase (MAPK) pathway. We speculated that this same gene may be either mutated at this site, or overexpressed, in pituitary adenomas.

Ghrelin in neuroendocrine organs and tumours

Ghrelin is a 28 amino-acid hormone with multiple functions. It is predominantly produced by the stomach but has also been detected in other organs, including the small intestine, pancreas, hypothalamus and pituitary, as well as in the immune system and almost every other normal human tissue examined. It is also present in neuroendocrine tumours, pituitary adenomas, endocrine tumours of the pancreas, breast tumours, and thyroid and medullary thyroid carcinomas. Ghrelin is a brain-gut peptide with growth hormone-releasing and appetite-inducing activities, and is the endogenous ligand of the G protein-coupled growth hormone secretagogue receptor (GHS-R). In this review we comprehensively summarize the available data regarding (a) the expression of ghrelin and the GHS-R in normal endocrine tissues and in pituitary adenomas and neuroendocrine tumours, (b) the levels of circulating ghrelin in patients with pituitary adenomas and neuroendocrine tumours and (c) the effects of ghrelin administration in these patients on the levels of other hormones and on the rate of proliferation of the tumour. It is clear that ghrelin has many more functions and is involved in many more processes than was initially postulated, and its endocrine, paracrine and autocrine effects play a role in its physiological and pathophysiological functions.

Protein western array analysis in human pituitary tumours: insights and limitations

The molecular analysis of pituitary tumours has received a great deal of attention, although the majority of studies have concentrated on the genome and the transcriptome. We aimed to study the proteome of human pituitary adenomas. A protein array using 1005 monoclonal antibodies was used to study GH-, corticotrophin- and prolactin-secreting as well as non-functioning pituitary adenomas (NFPAs). Individual protein expression levels in the tumours were compared with the expression profile of normal pituitary tissue. Out of 316 proteins that were detected in the pituitary tissue samples, 116 proteins had not previously been described in human pituitary tissue. Four prominent differentially expressed proteins with potential importance to tumorigenesis were chosen for validation by immunohistochemistry and western blotting. In the protein array analysis heat shock protein 110 (HSP110), a chaperone associated with protein folding, and B2 bradykinin receptor, a potential regulator of prolactin secretion, were significantly overexpressed in all adenoma subtypes, while C-terminal Src kinase (CSK), an inhibitor of proto-oncogenic enzymes, and annexin II, a calcium-dependent binding protein, were significantly underexpressed in all adenoma subtypes. The immunohistochemical analysis confirmed the overexpression of HSP110 and B2 bradykinin receptor and underexpression of CSK and annexin II in pituitary adenoma cells when compared with their corresponding normal pituitary cells. Western blotting only partially confirmed the proteomics data: HSP110 was significantly overexpressed in prolactinomas and NFPAs, the B2 bradykinin receptor was significantly overexpressed in prolactinomas, annexin II was significantly underexpressed in somatotrophinomas, while CSK did not show significant underexpression in any tumour. Protein expression analysis of pituitary samples disclosed both novel proteins and putative protein candidates for pituitary tumorigenesis, though validation using conventional techniques are necessary to confirm the protein array data.

A new mutation in the MEN1 gene

The multiple endocrine neoplasia type 1 (MEN1) is an autosomal dominantly inherited syndrome with an estimated prevalence of 1 to 10 per 100,000 in the general population. Patients with MEN1 develop various combinations of different endocrine tumors that mainly involve the parathyroid glands (90e97%), the pancreatic islet cells and duodenum (30e80%), and the anterior pituitary gland (15e50%). The prognosis of MEN1 is mainly related to the development of entero-pancreatic tumors. They are usually benign, small and multiple, nonfunctional, and with the tendency to recur after surgical removal [1]. MEN 1 is caused by germline mutations in the MEN1 gene, mapped to chromosome 11q13. This gene encodes for a 610eamino acid protein known as menin, which behaves as a tumor-suppressor gene [2]. Mutations most often lead to a truncated protein [3], resulting in major changes of the menin structure or in its absence, with loss of tumor-suppressing function and deregulation of cell growth and cell cycle. This results in an increased risk of developing multiple endocrine tumors [4,5]. MEN1 gene mutations have been reported in MEN1 syndrome [6] and in sporadic endocrine tumors [7]. The phenotypic expression of MEN1 may vary extensively between families and even among affected members within the same family [8]. In addition to variable penetrance of the MEN1 gene, it has been suggested that disease expression may be influenced by geneeenvironment and geneegene interactions [9]. We report on a new splice variant 4676-2A / G of MEN1, which causes the production of a truncated protein, observed in a woman with pancreatic endocrine tumors. In April 2008, a 28-year-old woman presented with a 1-year history of recurrent abdominal pain, vomiting, and weight loss. She reported a vague family history positive for unspecified tumors. According to her medical history, she had undergone a pancreaticoduodenectomy with an uncertain diagnosis of a low-grade endocrine tumor back in December 2003. Since November 2007, the patient complained of many episodes of abdominal pain and vomiting, as well as a rapid weight loss (8 kilograms in few weeks). She was then hospitalized in Naples, where she underwent positron emission tomography, which showed a nonhomogeneous accumulation of the tracer at the posterior stomach wall and in the subcutaneous adipose tissue in the right anterior abdominal wall. Scintigraphy with 111In-pentetreotide (Octreoscan, Mallinckrodt Medical, Petten, NL) and abdominal magnetic resonance imaging (MRI) were negative for a relapse of the pancreatic tumor. During

Vasostatin-1: A novel circulating biomarker for ileal and pancreatic neuroendocrine neoplasms

Background Chromogranin A (CgA) is a plasma biomarker widely used in the follow-up of patients with neuroendocrine neoplasms (NENs). However, its accuracy as a tumor biomarker is relatively low because plasma CgA can increase also in patients with other diseases or in subjects treated with proton-pump inhibitors (PPIs), a class of widely-used drugs. Methods In the attempt to identify a more reliable biomarker for NENs, we investigated, by ELISA, the circulating levels of full-length CgA (CgA1-439) and of various CgA-derived fragments in 17 patients with ileal or pancreatic NENs, 10 healthy controls, and 21 healthy volunteers before and after treatment with PPIs. Results Patients with ileal or pancreatic NENs showed increased plasma levels of total-CgA and CgA1-76 fragment (vasostatin-1, VS-1) compared to controls [median (25th-75th-percentiles); total-CgA: 1.85 nM (1.01–4.28) vs 0.75 nM (0.52–0.89), p = 0.004; VS-1: 2.76 nM (1.09–7.10) vs 0.29 nM (0.26–0.32), p<0.001, respectively], but not of CgA1-439 or CgA1-373 fragment. VS-1 positively correlated with total-CgA (r = 0.65, p<0.001). The Receiver Operating Characteristic area under the curve was 0.9935 for VS-1 and 0.8824 for total-CgA (p = 0.067). Treatment of patients with somatostatin analogues decreased both total-CgA and VS-1. In contrast, administration of PPIs increased the plasma levels of total-CgA, but not of VS-1. Conclusion These findings suggest that plasma VS-1 is a novel biomarker for ileal and pancreatic NENs. Considering that VS-1 is a well-defined fragment not induced by proton-pump inhibitors, this polypeptide might represent a biomarker for NENs diagnosis and follow-up more accurate and easier to standardize than CgA.