Ghrelin Expression and Actions: A Novel Peptide for an Old Cell Type of the Diffuse Endocrine System

Ghrelin is a gastric peptide involved in food intake control and growth hormone release. Its cell localization has been defined in distinct ghrelin cells of the gastric mucosa in humans and other mammals. Ghrelin production was also described in a number of other sites of the diffuse endocrine system, including the pituitary, thyroid, lung, pancreas, adrenal gland, and intestine. In addition, ghrelin cells were identified early during fetal life and in the placenta and gonads. Finally, endocrine growths and tumors of the diffuse endocrine system may present ghrelin-producing cells, and in a few cases high levels of circulating ghrelin were reported. Besides its well-defined orexigenic role, ghrelin is likely to exert a local paracrine role similar to other brain-gut axis hormones. This review aims to summarize recent data on ghrelin cell distribution in the diffuse endocrine system and discuss local and general ghrelin function during development, adulthood, and endocrine tumor development.

Proteomic analysis of pancreatic endocrine tumor cell lines treated with the histone deacetylase inhibitor trichostatin A

Effects of the histone-deacetylases inhibitor trichostatin A (TSA) on the growth of three different human pancreatic endocrine carcinoma cell lines (CM, BON, and QGP-1) have been assessed via dosage-dependent growth inhibition curves. TSA determined strong inhibition of cell growth with similar IC(50) values for the different cell lines: 80.5 nM (CM), 61.6 nM (BON), and 86 nM (QGP-1), by arresting the cell cycle in G2/M phase and inducing apoptosis. 2DE and nano-RP-HPLC-ESI-MS/MS analysis revealed 34, 33, and 38 unique proteins differentially expressed after TSA treatment in the CM, BON, and QGP-1 cell lines, respectively. The most important groups of modulated proteins belong to cell proliferation, cell cycle, and apoptosis classes (such as peroxiredoxins 1 and 2, the diablo protein, and HSP27). Other proteins pertain to processes such as regulation of gene expression (nucleophosmin, oncoprotein dek), signal transduction (calcium-calmodulin), chromatin, and cytoskeleton organization (calgizzarin, dynein, and lamin), RNA splicing (nucleolin, HNRPC), and protein folding (HSP70). The present data are in agreement with previous proteomic analyses performed on pancreatic ductal carcinoma cell lines (Cecconi, D. et al.., Electrophoresis 2003; Cecconi, D. et al., J. Proteome Res. 2005) and place histone-deacetylases inhibitors among the potentially most powerful drugs for the treatment of pancreatic tumors.

Broad tumor spectrum in a mouse model of multiple endocrine neoplasia type 1

Multiple endocrine neoplasia type 1 (MEN1) is an inherited cancer predisposition syndrome typified by development of tumors in parathyroid, pituitary and endocrine pancreas, as well as less common sites including both endocrine and nonendocrine organs. Deletion or mutation of the tumor suppressor gene MEN1 on chromosome 11 has been identified in many cases of MEN1 as well as in sporadic tumors. The molecular biology of menin, the protein encoded by MEN1, remains poorly understood. Here we describe a mouse model of MEN1 in which tumors were seen in pancreatic islets, pituitary, thyroid and parathyroid, adrenal glands, testes and ovaries. The observed tumor spectrum therefore includes types commonly seen in MEN1 patients and additional types. Pancreatic pathology was most common, evident in over 80% of animals, while other tumor types developed with lower frequency and generally later onset. Tumors of multiple endocrine organs were observed frequently, but progression to carcinoma and metastasis were not evident. Tumors in all sites showed loss of heterozygosity at the Men1 locus, though the frequency in testicular tumors was only 36%, indicating that a different molecular mechanism of tumorigenesis occurs in those Leydig tumors that do not show loss of the normal Men1 allele. Menin expression was below the level of detection in ovary, thyroid and testis, but loss of nuclear menin immunoreactivity was observed uniformly in all pancreatic islet adenomas and in some hyperplastic islet cells, suggesting that complete loss of Men1 is a critical point in islet tumor progression in this model.

The role of imatinib mesylate (Glivec) for treatment of patients with malignant endocrine tumors positive for c-kit or PDGF-R

Imatinib mesylate (IM), a small molecule that is a selective inhibitor of the ABL, platelet derived growth factor receptor (PDGFR-R) and stem cell ligand receptor (c-kit) tyrosine kinases (TK). IM was also found to inhibit the TK activity of BCR/ABL fusion protein produced in chronic myelogenous leukemia, with marked clinical activity against the disease. Since both PDGF-R and c-kit both having a putative role in tumorigenesis, we investigated the efficacy and safety of the use of IM in patients with endocrine tumors unresponsive to conventional therapies that expressed c-kit and/or PDGF-R (within the framework of a comprehensive phase II multi-center study of IM in patients with solid tumors). IM was initiated at a dose of 400 mg/day, with possible dose escalation within 1 week to 600 mg/day and an option to raise the dose to 800 mg/day in the event of progression and in the absence of safety concerns for a period of up to 12 months. Between September 2002 and July 2003, 15 adult patients with disseminated endocrine tumors were recruited as follows: medullary thyroid carcinoma (MTC, n = 6); adrenocortical carcinoma (ACC, n = 4); malignant pheochromocytoma (pheo, n = 2); carcinoid (non-secreting, n = 2), neuroendocrine tumor (NET, n = 1). No objective responses were observed. MTC--disease progression in 4 patients, and treatment discontinuation in 2 patients due to adverse events; ACC--disease progression in 3 patients, and treatment discontinuation in 1 patient due to severe psychiatric adverse event; Pheo--disease progression in 2 patients; Carcinoid--stable disease in 1 patient (6.5 months), and disease progression in 1 patient; NET--disease progression in 1 patient. IM does not appear to be useful for treatment of malignant endocrine tumors, also causing significant toxicity in this patient population.

[The incidence of somatostatin receptors in human neoplasms in the light of ex vivo-in vitro studies]

Human neoplastic cells express and often even over-express the somatostatin receptors (sstr). It concerns not only pituitary tumors and the so-called neuroendocrine tumors of the gut, but many other neoplasms, including the non-endocrine cancers. The incidence of sstr is important because it determines the possibility of treatment with SST (somatostatin) analogs. The examination of sstr is possible under the in vivo conditions, by means of the receptor scintigraphy using the radiolabeled SST analogs. The receptors can be also examined under the ex vivo-in vitro conditions, using the post-surgical or biopsy specimens. Among the in vitro (ex vivo) methods, the immunohistochemical investigation with specific anti-receptor antibodies seems to be particularly useful for routine clinical diagnostics. This review presents the data, obtained by means of different in vitro techniques, on the incidence of five sstr subtypes in the different human tumors, deriving from endocrine glands, diffuse neuroendocrine cells as well as in neoplasms considered as non-endocrine.

Endocrine tumor and intraductal papillary mucinous neoplasm of the pancreas: a fortuitous association?

OBJECTIVES

Pancreatic endocrine tumors (PETs) and intraductal papillary mucinous neoplasms (IPMNs) of the pancreas are rare diseases of the pancreas. Cases of association of endocrine and exocrine neoplasms of the pancreas have been reported, corresponding to mixed or amphicrine tumors. The aim of this report is to describe a series of 6 patients with an original association of IPMN and PET of the pancreas.

METHODS

Among 108 and 103 patients operated on in our center between January 1997 and December 2003 for PETs and IPMNs, respectively, we identified 6 patients with both PET and IPMN, diagnosed on pathologic examination with an immunohistochemical study.

RESULTS

Preoperative diagnosis was unspecified pancreatic tumor (n = 1), IPMN (n = 2), and association of PET and IPMN (n = 3). IPMN involved the main pancreatic duct in 4 patients and was classified as benign (n = 4), borderline (n = 1), or malignant noninvasive (n = 1). PETs measured 1.1 to 3 cm and were malignant in 1 patient (lymph node invasion). When analyzed by immunohistochemistry, 2 cases expressed glucagon, 1 expressed somatostatin, and 1 expressed insulin.

CONCLUSION

This study describes a new aspect of endocrine-exocrine pancreatic neoplasm association. The frequency of the association of PET and IPMN is too large to be fortuitous. Further studies are needed to understand its mechanism.

A panel of 11 region-specific radioimmunoassays for measurements of human chromogranin A

INTRODUCTION

The primary structure of human chromogranin A (CgA) not only contains 10 pairs of basic amino acids, which are potential cleavage sites for specific endogenous proteases, but also other sites in the molecule can be subjected to cleavage. Several CgA-related peptides have been identified in tissue, and many of the biological effects attributed to CgA seem to be mediated by these peptides.

MATERIALS AND METHODS

Peptides homologous to defined parts of the human CgA molecule were selected and synthesised. Antibodies were raised, and 11 specific radioimmunoassays were developed. Plasma samples from 20 patients with neuroendocrine tumours were collected and measured in all assays.

RESULTS

All assays measured circulating levels of CgA-derived peptides. Only four of the assays measured concentrations that correlated with that of total CgA. However, concentrations of the individual CgA-related peptides were generally lower than the concentration of total CgA. Different neuroendocrine tumours seem to process CgA differently. The ratio between a given region-specific assay and total CgA is inversely correlated to tumour activity.

CONCLUSION

The assays presented allow measurements of defined regions of CgA and will thus become important tools for further studies of processing of CgA.

Loss of p27 nuclear expression in a prognostically favorable subset of well-differentiated pancreatic endocrine neoplasms

Decreased expression of p27 occurs in aggressive colon, breast, and prostate neoplasms; p27 loss often correlates with worsened prognosis. Paradoxical overexpression has been described in benign and malignant pancreatic endocrine neoplasms (PENs). To investigate prognostic usefulness of p27 expression in PENs, we immunolabeled 42 primary PENs, with or without metastases, for p27 and separated lesions using a nuclear labeling index (NLI) of 10%. Of the 42 lesions, 26 demonstrated a 10% or higher NLI and 16 an NLI less than 10%. Comparison of lymph node status revealed that 50% of primary PENs with a 10% or higher NLI (13/26) demonstrated lymph node metastases, whereas only 6% of lesions with an NLI of less than 10% (1/16) demonstrated lymph node metastases (P = .0067). We next examined 11 liver and 7 lymph node metastases for p27 immunolabeling to determine whether p27 also is paradoxically retained in lesions that have metastasized. All 18 lesions demonstrated an NLI of 10% or higher for p27. Expression of p27 protein therefore appears to be lost in a subset of well-differentiated PENs with indolent features but paradoxically retained in PENs associated with metastatic disease.

Ghrelin expression in gut endocrine growths

We aimed to assess the occurrence of ghrelin, a new gut hormone, in endocrine growths of the stomach. In addition, since ghrelin has been detected in other gut derivatives during adult and/or fetal life, we also studied endocrine tumours of the pancreas, intestine and lung. A specific serum generated against amino acids 13-28 of ghrelin was tested on 16 specimens of gastric mucosa with endocrine cell hyperplasia and on 75 endocrine tumours. Ghrelin-immunoreactive cells were moderately represented in normal, atrophic or hypertrophic gastric mucosa, as a rule with no obvious hyperplastic changes even in the presence of concurrent, prominent enterochromaffin-like cell hyperplasia associated with hypergastrinemia. Ghrelin cells were also found in tumour cell fractions of well-differentiated gastric (25 of 33, 76%), pancreatic (6 of 15, 40%) and pulmonary (4 of 8) endocrine tumours. No ghrelin immunoreactivity was detected in 14 intestinal tumours and in five poorly differentiated endocrine carcinomas of the stomach or pancreas. We conclude that ghrelin cells may take part in gut endocrine growths, with special reference to well-differentiated endocrine tumours of the stomach, independently from associated signs of endocrine hyperfunction.

Immunohistochemical detection of fibroblast growth factor receptors in normal endocrine cells and related tumors of the digestive system

Endocrine tumors (ETs) of the digestive system produce several growth factors including acidic and basic fibroblast growth factors (aFGF and bFGF, respectively), which are thought to be involved in the growth of tumor cells and in the proliferation of tumor stromal cells. Their actions depend on binding to four specific receptors--FGFR1, FGFR2, FGFR3, and FGFR4--whose distribution in normal endocrine cells and related tumors of the gastroenteropancreatic (GEP) system has previously been examined. Formalin-fixed, paraffin-embedded normal tissues and 60 well-characterized GEP endocrine tumors were immunostained using specific antibodies directed against various GEP hormones, aFGF, FGFR1, FGFR2, FGFR3, and FGFR4. Acidic FGF immunoreactivity (IR) was found in gut EC cells; FGFR1 immunoreactivity in rare duodenal endocrine cells and in pancreatic A cells; FGFR2 immunoreactivity in gastric and duodenal G cells, pancreatic B cells, and rectal EC cells; FGFR3 immunoreactivity in duodenal G cells; and FGFR4 immunoreactivity in rectal L cells and in pancreatic B, PP, and A cells. Immunoreactivity for at least one of the four FGFRs was found in all tumors, independently of FGFR expression in the putative cell of origin. EC cell tumors, which were all positive for aFGF, were found to express at least three different FGFRs. FGFRs also were localized in the stromal cells of all the tumors examined. The tumor stroma was more abundant in EC cell tumors than in other types of neoplasms. The results suggest that aFGF-FGFR interaction may be involved in the modulation of normal endocrine cell functions and in the regulation of tumor growth and stromal proliferation of EC cell carcinoids.

Presence of sorbin in human digestive tract and endocrine digestive tumours

BACKGROUND

Sorbin, a 153 amino acid peptide isolated from porcine intestine, was localised by immunohistochemistry in endocrine cells of the intestinal mucosa and pancreas and in the enteric nervous system in the pig.

AIMS

To identify sorbin cells in normal human digestive tissues and to explore the expression of sorbin in 37 digestive endocrine tumours: 14 intestinal carcinoid tumours and 23 endocrine pancreatic tumours including six insulinomas.

METHODS

Two polyclonal antibodies against the C-terminal and the N-terminal sequences of porcine sorbin raised in rabbit were used to evaluate sorbin expression by immunohistochemistry.

RESULTS

In the human digestive tract, sorbin, characterised by both C-terminal and N-terminal immunoreactivity, was found in enterochromaffin cells of the gastric and intestinal epithelium from the pyloric junction to the descending colon. C-Terminal sorbin immunoreactivity alone was found in plexii from the enteric nervous system and in some insulin-containing cells of normal pancreas. C-Terminal and N-terminal antibodies disclosed sorbin in five of 14 intestinal carcinoid tumours; C-terminal antibody alone disclosed a C-terminal sorbin peptide in two of six insulinomas and three of 17 endocrine pancreatic tumours. The presence of sorbin was not associated with a specific clinical syndrome.

CONCLUSIONS

Sorbin is present in the digestive tract in several forms. It is expressed in some intestinal and pancreatic endocrine tumours.

Immunohistochemical localization of alpha- and betaA-subunits of inhibin/activin in human normal endocrine cells and related tumors of the digestive system

Activin A and inhibin A, first isolated from the ovary, are dimeric proteins able to modulate pituitary FSH secretion. Inhibin A is a heterodimer composed of one alpha-subunit and one betaA-subunit (alpha-betaA), while activin A is a homodimer of the betaA-subunit (betaA-betaA). Their identification in several tissues has suggested that they have numerous physiological functions, acting as either paracrine or autocrine factors. The aim of this study was to evaluate the expression of activin A and inhibin A in normal endocrine cells and in 70 endocrine tumours from different sites in the gastro-entero-pancreatic system, using specific monoclonal antibodies directed against the alpha- and betaA-subunits of inhibin/activin. Immunoreactivity for the betaA-subunit, but not for the alpha-subunit, was observed in normal G, EC, and GIP cells of the antrum and duodenum, and in pancreatic A cells. BetaA-subunit expression was observed in G cell and A cell tumours, and in a few insulinomas and ileal EC cell carcinoids. The alpha-subunit was found in rare cells in 7 of the 70 tumours and was colocalized with the betaA-subunit in only 1 tumor. Specific types of endocrine cells from the gut and pancreas appear to produce only activin A, a possible paracrine or autocrine modulator. Activin A is mainly produced by tumours derived from endocrine cells that normally express it.

Peptide YY expression is an early event in colonic endocrine cell differentiation: evidence from normal and transgenic mice

The hormone peptide YY is produced by endocrine cells in the pancreas, ileum and colon. We have previously shown that peptide YY is coexpressed in all four islet cell types in the murine pancreas when they first appear, suggesting a common peptide YY-producing progenitor. In the colon, peptide YY has been frequently identified in glucagon-expressing L-type endocrine cells. Characterization of colonic endocrine tumors in transgenic mice expressing simian virus 40 large T antigen under the control of the peptide YY gene 5′ flanking region revealed tumor cells producing not only peptide YY and glucagon, but also neurotensin, cholecystokinin, substance P, serotonin, secretin, and gastrin. This suggested that multiple enteroendocrine lineages were related to peptide YY-producing cells. Subsequent examination of the ontogeny of colonic endocrine differentiation in nontransgenic mice revealed that peptide YY was the first hormone to appear during development, at embryonic day 15.5. Between embryonic days 16.5 and 18.5, cells expressing glucagon, cholecystokinin, substance P, serotonin, secretin, neurotensin, gastrin and somatostatin first appeared and peptide YY was coexpressed in each cell type at this time. Peptide YY coexpression continued in a significant fraction of most enteroendocrine cell types throughout fetal and postnatal development and into adulthood, with the exception of serotonin-producing cells. This latter population of cells expanded dramatically after birth with rare coexpression of peptide YY. These studies indicate that expression of peptide YY is an early event in colonic endocrine differentiation and support the existence of a common progenitor for all endocrine cells in the colon.

Identification of a new chromogranin B fragment (314-365) in endocrine tumors

A rabbit antiserum was raised against the fragment (350-365) of human chromogranin B corresponding to the C-terminal end of a putative proteolytic fragment generated by the cleavage of a dibasic doublet located in position 366-367 of the precursor. A radioimmunoassay was developed. Chromatographic analysis of 10 endocrine tumor extracts (one liver metastasis of a gastrinoma, one liver metastasis of a medullary carcinoma of the thyroid, one VIPoma, one insulinoma, one nonsecreting pancreatic endocrine tumor, one local recurrence of a gut carcinoid, two pituitary gonadotropinoma, and two non-secreting pituitary adenomas) revealed the presence of two forms of immunoreactive material. The most abundant form had an apparent molecular weight of 4500 and was purified to homogeneity by successive reverse-phase HPLC chromatographies and partially sequenced. The N-terminal sequence of the peptide, established by automated Edman degradation, was A-S-E-E-E-P-E-Y-G-E-E-I-K-G-Y-P-V-Q and corresponded to the 314-332 sequence of human chromogranin B. Taking into account the specificity of the antiserum used for peptide identification, we deduced that the purified peptide was chromogranin B(314-365) and represented a new form generated by limited proteolysis of chromogranin B.

Chromogranin A(210-301) is the major form of pancreastatin-like material in human gut extracts and endocrine tumors

A radioimmunoassay of human pancreastatin was developed using a rabbit antiserum that selectively recognized the C-terminal amidated end of the peptide, and it was used for the identification of the molecular forms of pancreastatin in human gut (stomach, duodenum, small intestine, colon) and endocrine tumor extracts (liver metastasis of a gastrinoma and a medullary carcinoma of thyroid, one nonsecreting pancreatic tumor, one recurrence of a gut carcinoid, one vipoma and one insulinoma). In all gut extracts, a gel filtration chromatography revealed the presence of three peaks of pancreastatin-like immunoreactivity. The predominant form eluted with an apparent molecular weight higher than that of pancreastatin. This form was also predominant in the endocrine tumors analyzed, except in the insulinoma, where a lower molecular weight form predominated. The high molecular form was further purified from a liver metastasis of a gastrinoma. The pancreastatin-like immunoreactivity eluted in all the chromatographical systems (reverse-phase, ion exchange) as a single peak that was finally purified to homogeneity and sequenced. The sequence of the first 29 N-terminal amino acids was obtained unambiguously and corresponded to the sequence 210-238 of chromogranin A. Considering the selectivity of the assay used for peptide identification, this major form was identified as the fragment 210-301 of chromogranin A. It is likely that the predominant form of pancreastatin in human gut extracts and noninsular tumors is a 92 amino acid peptide.

Endocrine organ metastases in subjects with lobular carcinoma of the breast

OBJECTIVE

To define the frequency and pattern of endocrine organ metastases in patients dying of invasive lobular carcinoma.

DESIGN

Postmortem microscopic evaluation of the ovaries and adrenal, pituitary, thyroid, and parathyroid glands for breast cancer metastases.

SETTING

Roswell Park Cancer Institute, Buffalo, NY, between 1971 and 1990.

SUBJECTS

One hundred eighteen subjects who died of their cancer: 86 had infiltrating ductal carcinoma; 32, invasive lobular carcinoma.

MEAN OUTCOME MEASURE

Quantitative measurements to allow frequency determinations and statistical comparisons.

RESULTS

Endocrine organ metastases were found in 91% of the subjects with invasive lobular carcinoma vs 58% of subjects with infiltrating ductal carcinoma. The adrenal gland was most frequently involved. Multiple endocrine metastases were most common in the group with invasive lobular carcinoma.

CONCLUSIONS

A relationship exists between invasive lobular carcinoma and endocrine metastases. This indicates that antemortem endocrine evaluation may subsequently improve quality-of-life treatment.

Carcinosarcoma and separate neuroendocrine malignant tumor of a malignancy promoter, the gastric stump

We report a case of carcinosarcoma and separate neuroendocrine malignant tumor of the gastric stump. The case is interesting because of its unique pathological features and it confirms the role of the gastric stump as a very important "malignancy promoter".

Immunoreactivity and expression of amylin in gastroenteropancreatic endocrine tumors

Amylin was isolated from human insulinomas, but there has been only preliminary data regarding whether this peptide can also be detected in other types of gastroenteropancreatic endocrine tumors. In the present study, immunohistochemical staining of 87 gastroenteropancreatic endocrine tumors demonstrated amylin immunoreactivity in 21.8% of the neoplasmas. Thirteen of 15 insulinomas, three of 21 gastrinomas, two of 29 nonfunctioning tumors, and one of 18 carcinoids were amylin-immunoreactive. Seventeen of the 19 amylin-immunoreactive tumors were primarily located in the pancreas, but two tumors were found in the intestine. Measurements of amylin messenger RNA expression in a few tumors revealed amylin synthesis in these tumors. Amylin immunoreactivity did not correlate with invasion and metastasis. However, the rate of curative resections was significantly higher in amylin-immunoreactive tumors. These results demonstrate for the first time that amylin immunoreactivity is not restricted to insulinomas and can also occur rarely in endocrine tumors of the intestine.

[Current morphological methods in the study of endocrine tumors and their receptors]

The authors review the recent development of methods aimed at characterizing endocrine tumours. With new immunocytochemical methods, not only specific hormonal peptides can be identified but also hormonal precursors and their sites of processing. Immunodensitometry allows to quantify the hormonal cellular load and to assess hormonal synthesis via the precursors. Finally hormonal receptors can be identified by various techniques of autoradiography.

Nucleolar organizer regions and glycoprotein-hormone alpha-chain reaction as markers of malignancy in endocrine tumours of the pancreas

The value of silver staining of nucleolar organizer regions (AgNORs) and human chorionic gonadotropin alpha-chain reaction (HCG-alpha) as markers of malignancy was investigated in 60 primary pancreatic endocrine tumours, 37 of which had metastasized at the time of surgery, and in one of which metastases developed 4 years after surgery. Assessment of AgNORs by digital image analysis revealed few but large AgNORs (mean number 2.5 +/- 1.1; mean area 0.32 +/- 0.1 microns 2) in the 22 benign tumours and many but small AgNORs (mean number 5.1 +/- 1.9, P < 0.05; mean area 0.18 +/- 0.09 microns 2, P < 0.01) in the malignant tumours. Quantification of the number of AgNORs per tumour cell nucleolus (AgNOR distribution score) showed that 96% (26/27) of tumours exhibiting at least 5% of cells with more than six AgNORs per nucleolus showed metastases either at the time of diagnosis or up to 4 years after surgery. HCG-alpha immunoreactive cells were present in 25/38 (66%) malignant tumours and in 4/22 (18%) benign tumours. Combined evaluation of AgNOR distribution and HCG-alpha scores showed a high positive predictive value of 96% in cases with a raised AgNOR distribution score irrespective of the HCG-alpha status. A good negative predictive value (81%) was, however, only obtained if both parameters, AgNOR distribution and HCG-alpha scores, were negative. Thus, investigation of AgNORs and HCG-alpha is helpful in predicting malignancy in a high percentage of pancreatic endocrine tumours.

Transforming growth factor-alpha in normal and neoplastic human endocrine tissues

Transforming growth factor-alpha (TGF-alpha) is a polypeptide growth factor that binds to the epidermal growth factor receptor and is though to stimulate cell proliferation. It has been believed to play a role in tumor initiation by inducing the reversible transformed phenotype; overexpression of TGF-alpha may be important for tumor progression via autocrine stimulation and oncogene overexpression. Expression of TGF-alpha and the epidermal growth factor receptor has been documented in several nontumorous tissues and in a variety of tumors. This study used immunohistochemistry to localize TGF-alpha expression in normal and neoplastic endocrine tissues. Transforming growth factor-alpha was found in nontumorous hypothalamus, pituitary, thyroid, parathyroid, adrenal cortex and medulla, and pancreatic islets. Immunoreactivity was detected in most benign and malignant tumors of these tissues, as well as in endocrine neoplasms of the lung and gastrointestinal tract. Hypothalamic gangliocytomas, pheochromocytomas, and adrenal cortical carcinomas showed consistently greater immunoreactivity than their normal counterpart, but there was no correlation between degree of reactivity and tumor grade, stage, or hormone content. These results suggest that in endocrine tissues, TGF-alpha is unlikely to prove useful as a tumor marker but that the growth factor may play a role in both normal physiology and tumorigenesis.

Carcinoid tumor of the kidney with morphologic and immunohistochemical profile of a hindgut endocrine tumor: report of a case

A 54-year-old man underwent a radical nephrectomy for a presumed renal cell carcinoma. The tumor was large, showed areas of cystic degeneration and calcification, and had completely obliterated the normal renal parenchyma. The light microscopic appearance was atypical for renal cell carcinoma, and when electron microscopy revealed innumerable neurosecretory granules a diagnosis of carcinoid tumor was made. The tumor cells were argentaffin- and argyrophil-negative but were chromogranin-, neuron-specific enolase-, and leu-7-positive. When tested with a battery of antibodies against specific polypeptide hormones, the tumor exhibited diffuse pancreatic polypeptide and focal somatostatin immunoreactivity. Our case represents only the 16th case of carcinoid tumor of the kidney to be reported and the first with demonstrated pancreatic polypeptide immunoreactivity. The predominantly trabecular histology, nonreactivity with silver stains, and immunohistochemical profile of this case are common characteristics of hindgut carcinoids, suggesting that, like rectal carcinoids, renal carcinoids are tumors of hindgut endocrine cells.